2.4-3.2 GHz robust self-injecting injection-locked phase-locked loop

NASA Astrophysics Data System (ADS)

Yang, Jincheng; Zhang, Zhao; Qi, Nan; Liu, Liyuan; Liu, Jian; Wu, Nanjian

2018-04-01

In this paper, we propose a robust self-injecting injection-locked phase-locked loop (SI-ILPLL). It adopts a phase alignment loop (PAL) based on a subsampling phase frequency detector to align the phase between the injected pulse and the voltage-controlled oscillator (VCO) output. With the proposed phase frequency detector, the PAL performs phase alignment and the pulse generator can self-inject pulses into the VCO for injection locking. The subsampling phase detection and self-injection locking techniques can suppress the phase noise of the SI-ILPLL. The SI-ILPLL shows excellent robustness to environmental interference. The SI-ILPLL is implemented in 65 nm CMOS technology. It occupies an active area of 0.7 mm2. The measured root-mean-square (RMS) jitters at 3.2 GHz output without and with injection locking are 216 and 131 fs, respectively. When the supply voltage varies from 1.17 to 1.23 V and the temperature varies from 0 to 80 °C, the maximum jitter variation of all the output frequencies is less than 50 fs. The measured results demonstrate that even when a large interference appears at the supply voltage and unlocks the SI-ILPLL, the SI-ILPLL can self-recover its injection-locked state rapidly after the disturbance disappears, whereas the conventional ILPLL cannot self-recover its locked state after losing it. The power consumption of the SI-ILPLL is 7.4 mW under a 1.2 V supply voltage. The SI-ILPLL achieves a figure of merit (FOM) of -249 dB.

Au generation centres doped n+-Si: hole-injection adjustable anode for efficient organic light emission

NASA Astrophysics Data System (ADS)

Li, Y. Z.; Ran, G. Z.; Zhao, W. Q.; Qin, G. G.

2008-08-01

An organic light-emitting diode (OLED) with an n-Si-anode usually has an efficiency evidently lower than the OLED with the same structure with a p-Si-anode due to insufficient hole injection from the n-Si anode compared with the p-Si-anode. In this study, we find that introducing Au as generation centres with a suitable concentration into the n+-Si anode can enhance hole injection to match electron injection and then considerably promote the power efficiency. With optimizing Au generation centre concentration in the n+-Si anode, the OLED with a structure of n+-Si: Au/NPB/AlQ/Sm/Au reaches a highest power efficiency of 1.0 lm W-1, evidently higher than the reported highest power efficiency of 0.2 lm W-1 for its p-Si-anode counterpart. Furthermore, when the electron injection is enhanced by adopting BPhen:Cs2CO3 partly instead of AlQ as the electron transport material, and the Au generation centre concentration in the n+-Si anode is promoted correspondingly, then a highest power efficiency of 1.8 lm W-1 is reached. The role of Au generation centres in the n+-Si anode is discussed.

Targeted polymeric micelles for siRNA treatment of experimental cancer by intravenous injection.

PubMed

Christie, R James; Matsumoto, Yu; Miyata, Kanjiro; Nomoto, Takahiro; Fukushima, Shigeto; Osada, Kensuke; Halnaut, Julien; Pittella, Frederico; Kim, Hyun Jin; Nishiyama, Nobuhiro; Kataoka, Kazunori

2012-06-26

Small interfering ribonucleic acid (siRNA) cancer therapies administered by intravenous injection require a delivery system for transport from the bloodstream into the cytoplasm of diseased cells to perform the function of gene silencing. Here we describe nanosized polymeric micelles that deliver siRNA to solid tumors and elicit a therapeutic effect. Stable multifunctional micelle structures on the order of 45 nm in size formed by spontaneous self-assembly of block copolymers with siRNA. Block copolymers used for micelle formation were designed and synthesized to contain three main features: a siRNA binding segment containing thiols, a hydrophilic nonbinding segment, and a cell-surface binding peptide. Specifically, poly(ethylene glycol)-block-poly(L-lysine) (PEG-b-PLL) comprising lysine amines modified with 2-iminothiolane (2IT) and the cyclo-Arg-Gly-Asp (cRGD) peptide on the PEG terminus was used. Modification of PEG-b-PLL with 2IT led to improved control of micelle formation and also increased stability in the blood compartment, while installation of the cRGD peptide improved biological activity. Incorporation of siRNA into stable micelle structures containing the cRGD peptide resulted in increased gene silencing ability, improved cell uptake, and broader subcellular distribution in vitro and also improved accumulation in both the tumor mass and tumor-associated blood vessels following intravenous injection into mice. Furthermore, stable and targeted micelles inhibited the growth of subcutaneous HeLa tumor models and demonstrated gene silencing in the tumor mass following treatment with antiangiogenic siRNAs. This new micellar nanomedicine could potentially expand the utility of siRNA-based therapies for cancer treatments that require intravenous injection.

Passivated p-type silicon: Hole injection tunable anode material for organic light emission

NASA Astrophysics Data System (ADS)

Zhao, W. Q.; Ran, G. Z.; Xu, W. J.; Qin, G. G.

2008-02-01

We find that hole injection can be enhanced simply by selecting a lower-resistivity p-Si anode to match an electron injection enhancement for organic light emitting diodes with ultrathin-SiO2-layer-passivated p-Si anode (Si-OLED). For a Si-OLED with ordinary AlQ electron transport layer, the optimized resistivity of the p-Si anode is 40Ωcm; for that with n-doped Bphen electron transport layer, it decreases to 5Ωcm. Correspondingly, the maximum power efficiency increases from 0.3to1.9lm /W, even higher than that of an indium tin oxide control device (1.4lm/W). This passivated p-type silicon is a hole injection tunable anode material for OLED.

Diverse patterns of perilymphatic space enhancement in the rat inner ear after intratympanic injection of two different types of gadolinium: a 9.4-tesla magnetic resonance study.

PubMed

Park, Mina; Lee, Ho Sun; Choi, Jun-Jae; Kim, Hyeonjin; Lee, Jun Ho; Oh, Seung Ha; Suh, Myung-Whan

2015-01-01

To compare the quality of perilymphatic enhancement in the rat inner ear after intratympanic injection of two types of gadolinium with a 9.4-tesla micro-MRI. Gadolinium was injected into the middle ear in 6 Sprague-Dawley rats via the transtympanic route. The left ear was injected with Gd-DO3A-butrol first, and then the right ear was injected with Gd-DOTA. MR images of the inner ear were acquired 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, and 4 h after intratympanic (IT) injection using an Agilent MRI system 9.4T/160/AS. The normalized signal intensity was quantitatively analyzed at the scala vestibuli (SV), scala media, and scala tympani (ST) using a Marosis M-view system. Then the normalized signal intensities (SIs) were compared between the two contrast agents. For Gd-DO3A-butrol, the SI was as low as 1.0-1.5 throughout 1-4 h at the SV and ST of the basal turn. The maximum SI was 1.5 ± 0.5 at the SV (2 h) and 1.3 ± 0.5 at the ST (2 h). For Gd-DOTA, the 1-hour postinjection SI at the basal turn was 2.5 ± 0.5 at the SV, 1.6 ± 0.3 at the ST, and 1.2 ± 0.3 at the scala media. In the apical turn, the maximum SI was reached after 2.5 h. The maximum SI in the apical turn was 1.8 ± 0.4 at the SV (3.5 h), 1.8 ± 0.4 at the ST (4 h), and 1.4 ± 0.3 at the scala media (4 h). We were able to clearly visualize and separate the ST and SV using IT Gd and 9.4-tesla micro-MRI. We recommend using Gd-DO3A-butrol over Gd-DOTA and to perform the MRI 2.5 h after using IT Gd in the rat inner ear. © 2015 S. Karger AG, Basel.

Partially silencing brain toll-like receptor 4 prevents in part left ventricular remodeling with sympathoinhibition in rats with myocardial infarction-induced heart failure.

PubMed

Ogawa, Kiyohiro; Hirooka, Yoshitaka; Kishi, Takuya; Ide, Tomomi; Sunagawa, Kenji

2013-01-01

Left ventricular (LV) remodeling and activation of sympathetic nervous system (SNS) are cardinal features of heart failure. We previously demonstrated that enhanced central sympathetic outflow is associated with brain toll-like receptor 4 (TLR4) probably mediated by brain angiotensin II type 1 receptor in mice with myocardial infarction (MI)-induced heart failure. The purpose of the present study was to examine whether silencing brain TLR4 could prevent LV remodeling with sympathoinhibition in MI-induced heart failure. MI-induced heart failure model rats were created by ligation of left coronary artery. The expression level of TLR4 in brainstem was significantly higher in MI-induced heart failure treated with intracerebroventricular (ICV) injection of hGAPDH-SiRNA than in sham. TLR4 in brainstem was significantly lower in MI-induced heart failure treated with ICV injection of TLR4-SiRNA than in that treated with ICV injection of hGAPDH-SiRNA. Lung weight, urinary norepinephrine excretion, and LV end-diastolic pressure were significantly lower and LV dimension was significantly smaller in MI-induced heart failure treated with TLR4-SiRNA than in that treated with hGAPDH-SiRNA for 2 weeks. Partially silencing brain TLR4 by ICV injection of TLR4-SiRNA for 2 weeks could in part prevent LV remodeling with sympathoinhibition in rats with MI-induced heart failure. Brain TLR4 has a potential to be a target of the treatment for MI-induced heart failure.

The pH-Triggered Triblock Nanocarrier Enabled Highly Efficient siRNA Delivery for Cancer Therapy.

PubMed

Du, Lili; Zhou, Junhui; Meng, Lingwei; Wang, Xiaoxia; Wang, Changrong; Huang, Yuanyu; Zheng, Shuquan; Deng, Liandong; Cao, Huiqing; Liang, Zicai; Dong, Anjie; Cheng, Qiang

2017-01-01

Small interfering RNA (siRNA) therapies have been hampered by lack of delivery systems in the past decades. Nowadays, a few promising vehicles for siRNA delivery have been developed and it is gradually revealed that enhancing siRNA release from endosomes into cytosol is a very important factor for successful delivery. Here, we designed a novel pH-sensitive nanomicelle, PEG-PTTMA-P(GMA-S-DMA) (PTMS), for siRNA delivery. Owing to rapid hydrolysis in acidic environment, PTMS NPs underwent hydrophobic-to-hydrophilic transition in endosomes that enabled combination of proton sponge effect and raised osmotic pressure in endosomes, resulting in vigorous release of siRNAs from endosomes into cytosol. In vitro results demonstrated that PTMS/siRNA complexes exhibited excellent gene silencing effects in several cell lines. Their gene silencing efficiency could reach ~91%, ~87% and ~90% at the N/P ratio of 50/1 in MDA-MB-231, A549 and Hela cells respectively, which were better than that obtained with Lipofectamine 2000. The highly efficient gene silencing was then proven from enhanced siRNA endosomal release, which is mainly attributed to pH-triggered degradation of polymer and acid-accelerated siRNA release. In vivo experiments indicated that NPs/siRNA formulation rapidly accumulated in tumor sites after i.v. injection. Tumor growth was effectively inhibited and ~45% gene knockdown efficacy was determined at the siRRM2 dose of 1mg/kg. Meanwhile, no significant toxicity was observed during the whole treatment. We also found that PTMS/siRNA formulations could lead to significant gene silencing effects in liver (~63%) and skin (~80%) when injected by i.v. and s.c., respectively. This research work gives a rational strategy to optimize siRNA delivery systems for tumor treatments.

Antibody mediated in vivo delivery of small interfering RNAs via cell-surface receptors.

PubMed

Song, Erwei; Zhu, Pengcheng; Lee, Sang-Kyung; Chowdhury, Dipanjan; Kussman, Steven; Dykxhoorn, Derek M; Feng, Yi; Palliser, Deborah; Weiner, David B; Shankar, Premlata; Marasco, Wayne A; Lieberman, Judy

2005-06-01

Delivery of small interfering RNAs (siRNAs) into cells is a key obstacle to their therapeutic application. We designed a protamine-antibody fusion protein to deliver siRNA to HIV-infected or envelope-transfected cells. The fusion protein (F105-P) was designed with the protamine coding sequence linked to the C terminus of the heavy chain Fab fragment of an HIV-1 envelope antibody. siRNAs bound to F105-P induced silencing only in cells expressing HIV-1 envelope. Additionally, siRNAs targeted against the HIV-1 capsid gene gag, inhibited HIV replication in hard-to-transfect, HIV-infected primary T cells. Intratumoral or intravenous injection of F105-P-complexed siRNAs into mice targeted HIV envelope-expressing B16 melanoma cells, but not normal tissue or envelope-negative B16 cells; injection of F105-P with siRNAs targeting c-myc, MDM2 and VEGF inhibited envelope-expressing subcutaneous B16 tumors. Furthermore, an ErbB2 single-chain antibody fused with protamine delivered siRNAs specifically into ErbB2-expressing cancer cells. This study demonstrates the potential for systemic, cell-type specific, antibody-mediated siRNA delivery.

Estimated plasma bupivacaine concentration after single dose and eight-hour continuous intra-articular infusion of bupivacaine in normal dogs.

PubMed

Bubenik, Loretta; Hosgood, Giselle; Barker, Steven; Hicks, Merrin; Serra, Verna; Stout, Rhett

2007-12-01

To estimate maximum plasma concentration (C(max)) and time to maximum plasma (t(max)) bupivacaine concentration after intra-articular administration of bupivacaine for single injection (SI) and injection followed by continuous infusion (CI) in normal dogs. Cross-over design with a 2-week washout period. Healthy Coon Hound dogs (n=8). Using gas chromatography/mass spectrometry, canine plasma bupivacaine concentration was measured before and after SI (1.5 mg/kg) and CI (1.5 mg/kg and 0.3 mg/kg/h). Software was used to establish plasma concentration-time curves and estimate C(max), T(max) and other pharmacokinetic variables for comparison of SI and CI. Bupivacaine plasma concentration after SI and CI best fit a 3 exponential model. For SI, mean maximum concentration (C(max), 1.33+/-0.954 microg/mL) occurred at 11.37+/-4.546 minutes. For CI, mean C(max) (1.13+/-0.509 microg/mL) occurred at 10.37+/-4.109 minutes. The area under the concentration-time curve was smaller for SI (143.59+/-118.390 microg/mL x min) than for CI (626.502+/-423.653 microg/mL x min, P=.02) and half-life was shorter for SI (61.33+/-77.706 minutes) than for CI (245.363+/-104.415 minutes, P=.01). The highest plasma bupivacaine concentration for any dog was 3.2 microg/mL for SI and 2.3 microg/mL for CI. Intra-articular bupivacaine administration results in delayed absorption from the stifle into the systemic circulation with mean C(max) below that considered toxic and no systemic drug accumulation. Intra-articular bupivacaine can be administered with small risk of reaching toxic plasma concentrations in dogs, though toxic concentrations may be approached. Caution should be exercised with multimodal bupivacaine administration because plasma drug concentration may rise higher than with single intra-articular injection.

Integration of a Capacitive EIS Sensor into a FIA System for pH and Penicillin Determination

PubMed Central

Rolka, David; Poghossian, Arshak; Schöning, Michael J.

2004-01-01

A field-effect based capacitive EIS (electrolyte-insulator-semiconductor) sensor with a p-Si-SiO2-Ta2O5 structure has been successfully integrated into a commercial FIA (flow-injection analysis) system and system performances have been proven and optimised for pH and penicillin detection. A flow-through cell was designed taking into account the requirement of a variable internal volume (from 12 μl up to 48 μl) as well as an easy replacement of the EIS sensor. FIA parameters (sample volume, flow rate, distance between the injection valve and the EIS sensor) have been optimised in terms of high sensitivity and reproducibility as well as a minimum dispersion of the injected sample zone. An acceptable compromise between different FIA parameters has been found. For the cell design used in this study, best results have been achieved with a flow rate of 1.4 ml/min, distance between the injection valve and the EIS sensor of 6.5 cm, probe volume of 0.75 ml, cell internal volume of 12 μl. A sample throughput of at least 15 samples/h was typically obtained.

Intramyocardial Injection of siRNAs Can Efficiently Establish Myocardial Tissue-Specific Renalase Knockdown Mouse Model.

PubMed

Huang, Kun; Liu, Ju; Zhang, Hui; Wang, Jiliang; Li, Huili

2016-01-01

Ischaemia/reperfusion (I/R) injury will cause additional death of cardiomyocytes in ischaemic heart disease. Recent studies revealed that renalase was involved in the I/R injury. So, the myocardial tissue-specific knockdown mouse models were needed for the investigations of renalase. To establish the mouse models, intramyocardial injection of siRNAs targeting renalase was performed in mice. The wild distribution and high transfection efficiency of the siRNAs were approved. And the renalase expression was efficiently suppressed in myocardial tissue. Compared with the high cost, time consumption, and genetic compensation risk of the Cre/loxP technology, RNA interference (RNAi) technology is much cheaper and less time-consuming. Among the RNAi technologies, injection of siRNAs is safer than virus. And considering the properties of the I/R injury mouse models, the efficiency and durability of injection with siRNAs are acceptable for the studies. Altogether, intramyocardial injection of siRNAs targeting renalase is an economical, safe, and efficient method to establish myocardial tissue-specific renalase knockdown mouse models.

Knockdown of orexin type 2 receptor in the lateral pontomesencephalic tegmentum of rats increases REM sleep

PubMed Central

Chen, Lichao; McKenna, James T.; Bolortuya, Yunren; Brown, Ritchie E.

2012-01-01

Dysfunction of the orexin/hypocretin neurotransmitter system causes the sleep disorder narcolepsy, characterized by intrusion of rapid-eye-movement (REM) sleep-like events into normal wakefulness. The sites where orexins act to suppress REM sleep are incompletely understood. Previous studies suggested that the lateral pontomesencephalic tegmentum (lPMT) contains an important REM sleep inhibitory area, and proposed that orexins inhibit REM sleep via orexin type 2 receptors (OxR2) in this region. However, this hypothesis has heretofore not been tested. We thus performed bilateral injection of small interfering RNAs (siRNAs) targeting Ox2R into the lPMT on two consecutive days. This led to a ~30 % increase of time spent in REM sleep in both the dark and light periods for the first two days after injection, with a return to baseline over the next two post-injection days. This increase was mainly due to more longer (>120 s) REM episodes. Cataplexy-like episodes were not observed. The percentage of time spent in wakefulness and NREM sleep, as well as the power spectral profile of NREM and REM sleep, were unaffected. Control animals injected with scrambled siRNA had no sleep changes post-injection. Quantification of the knockdown revealed that unilateral microinjection of siRNAs targeting OxR2 into the lPMT induced a ~40% reduction of OxR2 mRNA two days following the injections when compared to the contralateral side receiving control (scrambled) siRNA. Orexin type 1 receptor (OxR1) mRNA level was unaffected. Our results indicate that removal of OxR2 neurotransmission in the lPMT enhances REM sleep by increasing the duration of REM episodes. PMID:23282008

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morishita, Sadaharu; Goto, Tetsuya; Nagase, Masaaki

Multiprocesses in a single plasma process chamber with high throughput require precise, sequential, high-speed alteration of partial pressures of multiple gas species. A conventional gas-distribution system cannot realize this because the system seriously overshoots gas pressure immediately following valve operation. Furthermore, chamber volume and conductance of gas piping between the system and chamber should both be considered because they delay the stabilizing time of gas pressure. Therefore, the authors proposed a new gas-distribution system without overshoot by controlling gas flow rate based on pressure measurement, as well as a method of pulse-controlled gas injection immediately following valve operation. Time variationmore » of measured partial pressure agrees well with a calculation based on an equivalent-circuit model that represents the chamber and gas piping between the system and chamber. Using pulse-controlled gas injection, the stabilizing time can be reduced drastically to 0.6 s for HBr added to pure Ar plasma, and 0.7 s for O{sub 2} added to Ar/HBr plasma; without the pulse control, the stabilizing times are 3 and 7 s, respectively. In the O{sub 2} addition case, rapid stabilization can be achieved during the period of line/space pattern etching of poly-Si on a thin SiO{sub 2} film. This occurs without anomalous etching of the underlying SiO{sub 2} film or the Si substrate near the sidewall, thus obtaining a wide process margin with high throughput.« less

Hydrosilylated Porous Silicon Particles Function as an Intravitreal Drug Delivery System for Daunorubicin

PubMed Central

Hartmann, Kathrin I.; Nieto, Alejandra; Wu, Elizabeth C.; Freeman, William R.; Kim, Jae Suk; Chhablani, Jay; Sailor, Michael J.

2013-01-01

Abstract Purpose To evaluate in vivo ocular safety of an intravitreal hydrosilylated porous silicon (pSi) drug delivery system along with the payload of daunorubicin (DNR). Methods pSi microparticles were prepared from the electrochemical etching of highly doped, p-type Si wafers and an organic linker was attached to the Si-H terminated inner surface of the particles by thermal hydrosilylation of undecylenic acid. DNR was bound to the carboxy terminus of the linker as a drug-loading strategy. DNR release from hydrosilylated pSi particles was confirmed in the excised rabbit vitreous using liquid chromatography–electrospray ionization–multistage mass spectrometry. Both empty and DNR-loaded hydrosilylated pSi particles were injected into the rabbit vitreous and the degradation and safety were studied for 6 months. Results The mean pSi particle size was 30×46×15 μm with an average pore size of 15 nm. Drug loading was determined as 22 μg per 1 mg of pSi particles. An ex vivo drug release study showed that intact DNR was detected in the rabbit vitreous. An in vivo ocular toxicity study did not reveal clinical or pathological evidence of any toxicity during a 6-month observation. Hydrosilylated pSi particles, either empty or loaded with DNR, demonstrated a slow elimination kinetics from the rabbit vitreous without ocular toxicity. Conclusions Hydrosilylated pSi particles can host a large quantity of DNR by a covalent loading strategy and DNR can be slowly released into the vitreous without ocular toxicity, which would appear if an equivalent quantity of free drug was injected. PMID:23448595

A biomaterial-assisted mesenchymal stromal cell therapy alleviates colonic radiation-induced damage.

PubMed

Moussa, Lara; Pattappa, Girish; Doix, Bastien; Benselama, Sarra-Louiza; Demarquay, Christelle; Benderitter, Marc; Sémont, Alexandra; Tamarat, Radia; Guicheux, Jérôme; Weiss, Pierre; Réthoré, Gildas; Mathieu, Noëlle

2017-01-01

Healthy tissues surrounding abdomino-pelvic tumours can be impaired by radiotherapy, leading to chronic gastrointestinal complications with substantial mortality. Adipose-derived Mesenchymal Stromal Cells (Ad-MSCs) represent a promising strategy to reduce intestinal lesions. However, systemic administration of Ad-MSCs results in low cell engraftment within the injured tissue. Biomaterials, able to encapsulate and withstand Ad-MSCs, can overcome these limitations. A silanized hydroxypropylmethyl cellulose (Si-HPMC) hydrogel has been designed and characterized for injectable cell delivery using the operative catheter of a colonoscope. We demonstrated that hydrogel loaded-Ad-MSCs were viable, able to secrete trophic factors and responsive to the inflammatory environment. In a rat model of radiation-induced severe colonic damage, Ad-MSC + Si-HPMC improve colonic epithelial structure and hyperpermeability compared with Ad-MSCs injected intravenously or locally. This therapeutic benefit is associated with greater engraftment of Si-HPMC-embedded Ad-MSCs in the irradiated colonic mucosa. Moreover, macrophage infiltration near the injection site was less pronounced when Ad-MSCs were embedded in the hydrogel. Si-HPMC induces modulation of chemoattractant secretion by Ad-MSCs that could contribute to the decrease in macrophage infiltrate. Si-HPMC is suitable for cell delivery by colonoscopy and induces protection of Ad-MSCs in the tissue potentiating their therapeutic effect and could be proposed to patients suffering from colon diseases. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

PEGylation rate influences peptide-based nanoparticles mediated siRNA delivery in vitro and in vivo.

PubMed

Aldrian, Gudrun; Vaissière, Anaïs; Konate, Karidia; Seisel, Quentin; Vivès, Eric; Fernandez, Frédéric; Viguier, Véronique; Genevois, Coralie; Couillaud, Franck; Démèné, Héléne; Aggad, Dina; Covinhes, Aurélie; Barrère-Lemaire, Stéphanie; Deshayes, Sébastien; Boisguerin, Prisca

2017-06-28

Small interfering RNAs (siRNAs) present a strong therapeutic potential because of their ability to inhibit the expression of any desired protein. Recently, we developed the retro-inverso amphipathic RICK peptide as novel non-covalent siRNA carrier. This peptide is able to form nanoparticles (NPs) by self-assembling with the siRNA resulting in the fully siRNA protection based on its protease resistant peptide sequence. With regard to an in vivo application, we investigated here the influence of the polyethylene glycol (PEG) grafting to RICK NPs on their in vitro and in vivo siRNA delivery properties. A detailed structural study shows that PEGylation did not alter the NP formation (only decrease in zeta potential) regardless of the used PEGylation rates. Compared to the native RICK:siRNA NPs, low PEGylation rates (≤20%) of the NPs did not influence their cellular internalization capacity as well as their knock-down specificity (over-expressed or endogenous system) in vitro. Because the behavior of PEGylated NPs could differ in their in vivo application, we analyzed the repartition of fluorescent labeled NPs injected at the one-cell stage in zebrafish embryos as well as their pharmacokinetic (PK) profile after administration to mice. After an intra-cardiac injection of the PEGylated NPs, we could clearly determine that 20% PEG-RICK NPs reduce significantly liver and kidney accumulation. NPs with 20% PEGylation constitutes a modular, easy-to-handle drug delivery system which could be adapted to other types of functional moieties to develop safe and biocompatible delivery systems for the clinical application of RNAi-based cancer therapeutics. Copyright © 2017 Elsevier B.V. All rights reserved.

An amplified chemiluminescence system based on Si-doped carbon dots for detection of catecholamines.

PubMed

Amjadi, Mohammad; Hallaj, Tooba; Manzoori, Jamshid L; Shahbazsaghir, Tahmineh

2018-08-05

We report on a chemiluminescence (CL) system based on simultaneous enhancing effect of Si-doped carbon dots (Si-CDs) and cetyltrimethylammonium bromide (CTAB) on HCO 3 - -H 2 O 2 reaction . The possible CL mechanism is investigated and discussed. Excited-state Si-CDs was found to be the final emitting species, which are probably produced via electron and hole injection by oxy-radicals. The effect of several other heteroatom-doped CDs and undoped CDs was also investigated and compared with Si-CDs. Furthermore, it was found that catecholamines such as dopamine, adrenaline and noradrenaline remarkably diminish the CL intensity of Si-CD-HCO 3 - -H 2 O 2 -CTAB system. By taking advantage of this fact, a sensitive probe was designed for determination of dopamine, adrenaline and noradrenaline with a limit of detection of 0.07, 0.60 and 0.01 μM, respectively. The method was applied to the determination of catecholamines in human plasma samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Fluoroscopic Sacroiliac Joint Injection: Is Oblique Angulation Really Necessary?

PubMed

Khuba, Sandeep; Agarwal, Anil; Gautam, Sujeet; Kumar, Sanjay

2016-01-01

The conventional technique for sacroiliac (SI) joint injection involves aligning the anterior and posterior aspects of the SI joint under fluoroscopic guidance and then entering the SI joint in the most caudal aspect. We wish to highlight that there is no added advantage to aligning both the anterior and posterior joint lines of the SI joint as it is time consuming, associated with additional radiation exposure, and may make the entry into the posterior SI joint technically more difficult. Observational study. Pain Clinic, Department of Anesthesiology. With the patient lying prone on fluoroscopy table, SI joint injection is performed with a 22 G, 10 cm spinal needle in a true anteroposterior (AP) view, where anterior and posterior SI joint spaces are seen as separate entities, where the medial joint space represents the posterior SI joint and the lateral joint space represents the anterior SI joint. The distal 1 cm of the medial joint space is entered under AP view. If the SI joint is seen as a straight line rather than 2 joint spaces in the AP view then the image intensifier of the fluoroscope was tilted cranially to elongate the image of the lower part of the posterior SI joint, thus facilitating entry into this part of the joint which was confirmed by administering 0.3 to 0.5 mL of radiopaque contrast medium. Sixty SI joints of 58 patients were injected under an AP fluoroscopic view. Forty-two (70%) SI joints were seen as 2 separate medial and lateral joint spaces and were entered in distal 1 cm of the medial joint space. In 18 (30%) joints seen as a straight line rather than 2 separate spaces, the image intensifier of the fluoroscope was tilted cranially to elongate the image of the lower part of the posterior SI joint and then the SI joint was entered in its distal 1 cm. Confirmation of entry into the SI joint was confirmed by with 0.3 to 0.5 mL of radiopaque contrast medium. In 4 cases the joints did not show the correct radiopaque contrast spread (3/42 and 1/18) although the needle seemed to be in the joint space. Small sample size. Aligning the anterior and posterior aspects of SI joint for fluoroscopic guided SI joint injection is not necessary for the success of the block.Key words: Sacroiliac joint, injection, anteroposterior view, oblique angulation, fluoroscopic technique.

Biodistribution of small interfering RNA at the organ and cellular levels after lipid nanoparticle-mediated delivery.

PubMed

Shi, Bin; Keough, Ed; Matter, Andrea; Leander, Karen; Young, Stephanie; Carlini, Ed; Sachs, Alan B; Tao, Weikang; Abrams, Marc; Howell, Bonnie; Sepp-Lorenzino, Laura

2011-08-01

Chemically stabilized small interfering RNA (siRNA) can be delivered systemically by intravenous injection of lipid nanoparticles (LNPs) in rodents and primates. The biodistribution and kinetics of LNP-siRNA delivery in mice at organ and cellular resolution have been studied using immunofluorescence (IF) staining and quantitative polymerase chain reaction (qPCR). At 0.5 and 2 hr post tail vein injection of Cy5-labeled siRNA encapsulated in LNP, the organ rank-order of siRNA levels is liver > spleen > kidney, with only negligible accumulation in duodenum, lung, heart, and brain. Similar conclusions were drawn by using qPCR to measure tissue siRNA levels as a secondary end point. siRNA levels in these tissues decreased by more than 10-fold after 24 hr. Within the liver, LNPs delivered siRNA to hepatocytes, Kupffer cells, and sinusoids in a time-dependent manner, as revealed by IF staining and signal quantitation methods established using OPERA/Columbus software. siRNA first accumulated in liver sinusoids and trafficked to hepatocytes by 2 hr post dose, corresponding to the onset of target mRNA silencing. Fluorescence in situ hybridization methods were used to detect both strands of siRNA in fixed tissues. Collectively, the authors have implemented a platform to evaluate biodistribution of siRNA across cell types and across tissues in vivo, with the objective of elucidating the pharmacokinetic and pharmacodynamic relationship to guide optimization of delivery vehicles. © The Author(s) 2011

Biodistribution of Small Interfering RNA at the Organ and Cellular Levels after Lipid Nanoparticle-mediated Delivery

PubMed Central

Shi, Bin; Keough, Ed; Matter, Andrea; Leander, Karen; Young, Stephanie; Carlini, Ed; Sachs, Alan B.; Tao, Weikang; Abrams, Marc; Howell, Bonnie; Sepp-Lorenzino, Laura

2011-01-01

Chemically stabilized small interfering RNA (siRNA) can be delivered systemically by intravenous injection of lipid nanoparticles (LNPs) in rodents and primates. The biodistribution and kinetics of LNP–siRNA delivery in mice at organ and cellular resolution have been studied using immunofluorescence (IF) staining and quantitative polymerase chain reaction (qPCR). At 0.5 and 2 hr post tail vein injection of Cy5-labeled siRNA encapsulated in LNP, the organ rank-order of siRNA levels is liver > spleen > kidney, with only negligible accumulation in duodenum, lung, heart, and brain. Similar conclusions were drawn by using qPCR to measure tissue siRNA levels as a secondary end point. siRNA levels in these tissues decreased by more than 10-fold after 24 hr. Within the liver, LNPs delivered siRNA to hepatocytes, Kupffer cells, and sinusoids in a time-dependent manner, as revealed by IF staining and signal quantitation methods established using OPERA/Columbus software. siRNA first accumulated in liver sinusoids and trafficked to hepatocytes by 2 hr post dose, corresponding to the onset of target mRNA silencing. Fluorescence in situ hybridization methods were used to detect both strands of siRNA in fixed tissues. Collectively, the authors have implemented a platform to evaluate biodistribution of siRNA across cell types and across tissues in vivo, with the objective of elucidating the pharmacokinetic and pharmacodynamic relationship to guide optimization of delivery vehicles. PMID:21804077

Silencing of sodium/hydrogen exchanger in the heart by direct injection of naked siRNA.

PubMed

Morgan, Patricio E; Correa, María V; Ennis, Irene L; Ennis, Irene E; Diez, Ariel A; Pérez, Néstor G; Cingolani, Horacio E

2011-08-01

Cardiac Na(+)/H(+) exchanger (NHE1) hyperactivity is a central factor in cardiac remodeling following hypertension, myocardial infarction, ischemia-reperfusion injury, and heart failure. Treatment of these pathologies by inhibiting NHE1 is challenging because specific drugs that have been beneficial in experimental models were associated with undesired side effects in clinical practice. In the present work, small interference RNA (siRNA) produced in vitro to specifically silence NHE1 (siRNA(NHE1)) was injected once in vivo into the apex of the left ventricular wall of mouse myocardium. After 48 h, left ventricular NHE1 protein expression was reduced in siRNA(NHE1)-injected mice compared with scrambled siRNA by 33.2 ± 3.4% (n = 5; P < 0.05). Similarly, NHE1 mRNA levels were reduced by 20 ± 2.0% (n = 4). At 72 h, siRNA(NHE1) spreading was evident from the decrease in NHE1 expression in three portions of the myocardium (apex, medium, base). NHE1 function was assessed based on maximal velocity of intracellular pH (pH(i)) recovery (dpH(i)/dt) after an ammonium prepulse-induced acidic load. Maximal dpH(i)/dt was reduced to 14% in siRNA(NHE1)-isolated left ventricular papillary muscles compared with scrambled siRNA. In conclusion, only one injection of naked siRNA(NHE1) successfully reduced NHE1 expression and activity in the left ventricle. As has been previously suggested, extensive NHE1 expression reduction may indicate myocardial spread of siRNA molecules from the injection site through gap junctions, providing a valid technique not only for further research into NHE1 function, but also for consideration as a potential therapeutic strategy.

Decrease of murine cytomegalovirus-induced retinitis by intravenous delivery of immediate early protein-3-specific siRNA.

PubMed

Marshall, Brendan; Mo, Juan; Covar, Jason; Atherton, Sally S; Zhang, Ming

2014-06-06

Retinitis induced by both human and murine cytomegaloviruses following immunosuppression is characterized by progressive loss of retinal architecture, due to necrosis of virus-infected cells as well as widespread apoptosis of uninfected bystander cells. Because small inhibitory RNA molecules (siRNA) can reduce murine cytomegalovirus (MCMV) gene expression and thereby inhibit virus replication in vitro, we tested siRNAs directed against MCMV immediate early protein-3 (IE-3) to determine if MCMV-induced retinitis could be alleviated in vivo. Immunosuppressed Balb/c mice (2.0 mg methylprednisolone acetate every 3 days beginning on day -2) were infected with 5 × 10(3) pfu of the K181 strain of MCMV via the supraciliary route. At day 2 post infection, mice were treated with various doses of IE-3-specific siRNA ranging from 0.1 nmol to 10 nmol, in a volume of 20 μL PBS via tail vein injection. Injected eyes were collected at various times post inoculation and subjected to plaque assay for virus titer, MCMV antigen staining, H&E staining, TUNEL assay, and Western blot for MCMV IE-3 protein. Small but significant amounts of fluorescently labeled IE-3-specific siRNA localized to the RPE layer 48 hours after intravenous injection. IE-3-specific siRNA significantly reduced virus titers at all concentrations tested (ranging from 0.1 nmol to 10 nmol), but the most potent effect of siRNA was observed at a dose of 1 nmol. We also observed that IE-3-specific siRNA produced a substantial decrease in MCMV titers and a substantial reduction in bystander cell apoptosis over the time course of virus infection. Systemic administration of IE-3-specific siRNA could alleviate MCMV retinitis by inhibiting virus replication and subsequent death of uninfected retinal cells. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Decrease of Murine Cytomegalovirus–Induced Retinitis by Intravenous Delivery of Immediate Early Protein-3–Specific siRNA

PubMed Central

Marshall, Brendan; Mo, Juan; Covar, Jason; Atherton, Sally S.; Zhang, Ming

2014-01-01

Purpose. Retinitis induced by both human and murine cytomegaloviruses following immunosuppression is characterized by progressive loss of retinal architecture, due to necrosis of virus-infected cells as well as widespread apoptosis of uninfected bystander cells. Because small inhibitory RNA molecules (siRNA) can reduce murine cytomegalovirus (MCMV) gene expression and thereby inhibit virus replication in vitro, we tested siRNAs directed against MCMV immediate early protein-3 (IE-3) to determine if MCMV-induced retinitis could be alleviated in vivo. Methods. Immunosuppressed Balb/c mice (2.0 mg methylprednisolone acetate every 3 days beginning on day −2) were infected with 5 × 103 pfu of the K181 strain of MCMV via the supraciliary route. At day 2 post infection, mice were treated with various doses of IE-3–specific siRNA ranging from 0.1 nmol to 10 nmol, in a volume of 20 μL PBS via tail vein injection. Injected eyes were collected at various times post inoculation and subjected to plaque assay for virus titer, MCMV antigen staining, H&E staining, TUNEL assay, and Western blot for MCMV IE-3 protein. Results. Small but significant amounts of fluorescently labeled IE-3–specific siRNA localized to the RPE layer 48 hours after intravenous injection. IE-3–specific siRNA significantly reduced virus titers at all concentrations tested (ranging from 0.1 nmol to 10 nmol), but the most potent effect of siRNA was observed at a dose of 1 nmol. We also observed that IE-3–specific siRNA produced a substantial decrease in MCMV titers and a substantial reduction in bystander cell apoptosis over the time course of virus infection. Conclusions. Systemic administration of IE-3–specific siRNA could alleviate MCMV retinitis by inhibiting virus replication and subsequent death of uninfected retinal cells. PMID:24906861

A novel therapeutic strategy for cartilage diseases based on lipid nanoparticle-RNAi delivery system.

PubMed

Wang, Shaowei; Wei, Xiaochun; Sun, Xiaojuan; Chen, Chongwei; Zhou, Jingming; Zhang, Ge; Wu, Heng; Guo, Baosheng; Wei, Lei

2018-01-01

Cartilage degeneration affects millions of people but preventing its degeneration is a big challenge. Although RNA interference (RNAi) has been used in human trials via silencing specific genes, the cartilage RNAi has not been possible to date because the cartilage is an avascular and very dense tissue with very low permeability. The objective of this study was to develop and validate a novel lipid nanoparticle (LNP)-siRNA delivery system that can prevent cartilage degeneration by knocking down specific genes. LNP transfection efficiency was evaluated in vitro and ex vivo. Indian Hedgehog ( Ihh ) has been correlated with cartilage degeneration. The in vivo effects of LNP-Ihh siRNA complexes on cartilage degeneration were evaluated in a rat model of surgery-induced osteoarthritis (OA). In vitro, 100% of chondrocytes were transfected with siRNA in the LNP-siRNA group. In accordance with the cell culture results, red positive signals could be detected even in the deep layer of cartilage tissue cultures treated by LNP-beacon. In vivo data showed that LNP is specific for cartilage, since positive signals were detected by fluorescence molecular tomography and confocal microscopy in joint cartilage injected with LNP-beacon, but not on the surface of the synovium. In the rat model of OA, intraarticular injection of LNP-Ihh siRNA attenuated OA progression, and PCR results showed LNP-Ihh siRNA exerted a positive impact on anabolic metabolism and negative impact on catabolic metabolism. This study demonstrates that our LNP-RNAi delivery system has a significantly chondroprotective effect that attenuates cartilage degeneration and holds great promise as a powerful tool for treatment of cartilage diseases by knocking down specific genes.

A novel therapeutic strategy for cartilage diseases based on lipid nanoparticle-RNAi delivery system

PubMed Central

Wang, Shaowei; Wei, Xiaochun; Sun, Xiaojuan; Chen, Chongwei; Zhou, Jingming; Zhang, Ge; Wu, Heng; Guo, Baosheng

2018-01-01

Background Cartilage degeneration affects millions of people but preventing its degeneration is a big challenge. Although RNA interference (RNAi) has been used in human trials via silencing specific genes, the cartilage RNAi has not been possible to date because the cartilage is an avascular and very dense tissue with very low permeability. Purpose The objective of this study was to develop and validate a novel lipid nanoparticle (LNP)-siRNA delivery system that can prevent cartilage degeneration by knocking down specific genes. Methods LNP transfection efficiency was evaluated in vitro and ex vivo. Indian Hedgehog (Ihh) has been correlated with cartilage degeneration. The in vivo effects of LNP-Ihh siRNA complexes on cartilage degeneration were evaluated in a rat model of surgery-induced osteoarthritis (OA). Results In vitro, 100% of chondrocytes were transfected with siRNA in the LNP-siRNA group. In accordance with the cell culture results, red positive signals could be detected even in the deep layer of cartilage tissue cultures treated by LNP-beacon. In vivo data showed that LNP is specific for cartilage, since positive signals were detected by fluorescence molecular tomography and confocal microscopy in joint cartilage injected with LNP-beacon, but not on the surface of the synovium. In the rat model of OA, intraarticular injection of LNP-Ihh siRNA attenuated OA progression, and PCR results showed LNP-Ihh siRNA exerted a positive impact on anabolic metabolism and negative impact on catabolic metabolism. Conclusion This study demonstrates that our LNP-RNAi delivery system has a significantly chondroprotective effect that attenuates cartilage degeneration and holds great promise as a powerful tool for treatment of cartilage diseases by knocking down specific genes. PMID:29440889

Efficient flow injection and sequential injection methods for spectrophotometric determination of oxybenzone in sunscreens based on reaction with Ni(II).

PubMed

Chisvert, A; Salvador, A; Pascual-Martí, M C; March, J G

2001-04-01

Spectrophotometric determination of a widely used UV-filter, such as oxybenzone, is proposed. The method is based on the complexation reaction between oxybenzone and Ni(II) in ammoniacal medium. The stoichiometry of the reaction, established by the Job method, was 1:1. Reaction conditions were studied and the experimental parameters were optimized, for both flow injection (FI) and sequential injection (SI) determinations, with comparative purposes. Sunscreen formulations containing oxybenzone were analyzed by the proposed methods and results compared with those obtained by HPLC. Data show that both FI and SI procedures provide accurate and precise results. The ruggedness, sensitivity and LOD are adequate to the analysis requirements. The sample frequency obtained by FI is three-fold higher than that of SI analysis. SI is less reagent-consuming than FI.

D-(/sup 3/H)aspartate retrograde labelling of callosal and association neurons of somatosensory areas I and II of cats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barbaresi, P.; Fabri, M.; Conti, F.

Experiments were carried out on cats to ascertain whether corticocortical neurons of somatosensory areas I (SI) and II (SII) could be labelled by retrograde axonal transport of D-(/sup 3/H)aspartate (D-(/sup 3/H)Asp). This tritiated enantiomer of the amino acid aspartate is (1) taken up selectively by axon terminals of neurons releasing aspartate and/or glutamate as excitatory neurotransmitter, (2) retrogradely transported and accumulated in perikarya, (3) not metabolized, and (4) visualized by autoradiography. A solution of D-(/sup 3/H)Asp was injected in eight cats in the trunk and forelimb zones of SI (two cats) or in the forelimb zone of SII (six cats).more » In order to compare the labelling patterns obtained with D-(/sup 3/H)Asp with those resulting after injection of a nonselective neuronal tracer, horseradish peroxidase (HRP) was delivered mixed with the radioactive tracer in seven of the eight cats. Furthermore, six additional animals received HRP injections in SI (three cats; trunk and forelimb zones) or SII (three cats; forelimb zone). D-(/sup 3/H)Asp retrograde labelling of perikarya was absent from the ipsilateral thalamus of all cats injected with the radioactive tracer but a dense terminal plexus of anterogradely labelled corticothalamic fibers from SI and SII was observed, overlapping the distribution area of thalamocortical neurons retrogradely labelled with HRP from the same areas. D-(/sup 3/H)Asp-labelled neurones were present in ipsilateral SII (SII-SI association neurones) in cats injected in SI. In these animals a bundle of radioactive fibres was observed in the rostral portion of the corpus callosum entering the contralateral hemisphere. There, neurones retrogradely labelled with silver grains were present in SI (SI-SI callosal neurons).« less

Intracellular cleavable poly(2-dimethylaminoethyl methacrylate) functionalized mesoporous silica nanoparticles for efficient siRNA delivery in vitro and in vivo.

PubMed

Lin, Daoshu; Cheng, Qiang; Jiang, Qian; Huang, Yuanyu; Yang, Zheng; Han, Shangcong; Zhao, Yuning; Guo, Shutao; Liang, Zicai; Dong, Anjie

2013-05-21

A low cytotoxicity and high efficiency delivery system with the advantages of low cost and facile fabrication is needed for the application of small interfering RNA (siRNA) delivery both in vitro and in vivo. For these prerequisites, cationic polymer-mesoporous silica nanoparticles (ssCP-MSNs) were prepared by surface functionalized mesoporous silica nanoparticles with disulfide bond cross-linked poly(2-dimethylaminoethyl methacrylate) (PDMAEMA). In vitro and in vivo evaluations were performed. The synthesized ssCP-MSNs are 100-150 nm in diameter with a pore size of 10 nm and a positively charged surface with a high zeta potential of 27 mV. Consequently, the ssCP-MSNs showed an excellent binding capacity for siRNA, and an enhancement in the cell uptake and cytosolic availability of siRNA. Furthermore, the intracellular reducing cleavage of the disulfide bonds cross-linking the PDMAEMA segments led to intracellular cleavage of PDMAEMA from ssCP-MSNs, which facilitated the intracellular triggered release of siRNA. Therefore, promoted RNA interference was observed in HeLa-Luc cells, which was equal to that of Lipofectamine 2000. Significantly, compared to Lipofectamine 2000, the ssCP-MSNs were more biocompatible, with low cytotoxicity (even non-cytotoxicity) and promotion of cell proliferation to HeLa-Luc cells. The in vivo systemic distribution studies certified that ssCP-MSNs/siRNA could prolong the duration of siRNA in vivo, and that they accumulated in the adrenal gland, liver, lung, spleen, kidney, heart and thymus after intravenous injection. Encouragingly, with the ability to deliver siRNA to a tumor, ssCP-MSNs/siRNA showed a tumor suppression effect in the HeLa-Luc xenograft murine model after intravenous injection. Therefore, the ssCP-MSNs cationic polymer-mesoporous silica nanoparticles with low cytotoxicity are promising for siRNA delivery.

A nanoparticle system specifically designed to deliver short interfering RNA inhibits tumor growth in vivo.

PubMed

Yagi, Nobuhiro; Manabe, Ichiro; Tottori, Tsuneaki; Ishihara, Atsushi; Ogata, Fusa; Kim, Jong Heon; Nishimura, Satoshi; Fujiu, Katsuhito; Oishi, Yumiko; Itaka, Keiji; Kato, Yasuki; Yamauchi, Masahiro; Nagai, Ryozo

2009-08-15

Use of short interfering RNA (siRNA) is a promising new approach thought to have a strong potential to lead to rapid development of gene-oriented therapies. Here, we describe a newly developed, systemically injectable siRNA vehicle, the "wrapsome" (WS), which contains siRNA and a cationic lipofection complex in a core that is fully enveloped by a neutral lipid bilayer and hydrophilic polymers. WS protected siRNA from enzymatic digestion, providing a long half-life in the systemic circulation. Moreover, siRNA/WS leaked from blood vessels within tumors into the tumor tissue, where it accumulated and was subsequently transfected into the tumor cells. Because the transcription factor KLF5 is known to play a role in tumor angiogenesis, we designed KLF5-siRNA to test the antitumor activity of siRNA/WS. KLF5-siRNA/WS exhibited significant antitumor activity, although neither WS containing control scrambled-siRNA nor saline containing KLF5-siRNA affected tumor growth. KLF5-siRNA/WS inhibited Klf5 expression within tumors at both mRNA and protein levels, significantly reducing angiogenesis, and we detected no significant acute or long-term toxicity. Our findings support the idea that siRNA/WS can be used to knock down specific genes within tumors and thereby exert therapeutic effects against cancers.

Ultrahigh-Speed Electrically Injected 1.55 micrometer Quantum Dot Microtube and Nanowire Lasers on Si

DTIC Science & Technology

2015-08-30

Ultrahigh-Speed Electrically Injected 1.55 um Quantum Dot Microtube and Nanowire Lasers on Si In this report, we describe the progress made in rolled...up InP-based tube lasers and in the growth and characterization of III-nitride nanowire structures on Si. We report on the demonstration of...injected AlGaN nanowire lasers that can operate in the UV-AII (315-340 nm), UV-B (280-315nm), and UV-C (200-280 nm). The views, opinions and/or findings

Sodium Iodate Produces a Strain-Dependent Retinal Oxidative Stress Response Measured In Vivo Using QUEST MRI.

PubMed

Berkowitz, Bruce A; Podolsky, Robert H; Lenning, Jacob; Khetarpal, Nikita; Tran, Catherine; Wu, Johnny Y; Berri, Ali M; Dernay, Kristin; Shafie-Khorassani, Fatema; Roberts, Robin

2017-06-01

We identify noninvasive biomarkers that measure the severity of oxidative stress within retina layers in sodium iodate (SI)-atrophy vulnerable (C57BL/6 [B6]) and SI-atrophy resistant (129S6/SvEvTac [S6]) mice. At 24 hours after administering systemic SI to B6 and S6 mice we measured: (1) superoxide production in whole retina ex vivo, (2) excessive free radical production in vivo based on layer-specific 1/T1 values before and after α-lipoic acid (ALA) administration while the animal was inside the magnet (QUEnch-assiSTed MRI [QUEST MRI]), and (3) visual performance (optokinetic tracking) ± antioxidants; control mice were similarly assessed. Retinal layer spacing and thickness in vivo also were evaluated (optical coherence tomography, MRI). SI-treated B6 mice retina had a significantly higher superoxide production than SI-treated S6 mice. ALA-injected SI-treated B6 mice had reduced 1/T1 in more retinal layers in vivo than in SI-treated S6 mice. Uninjected and saline-injected SI-treated B6 mice had similar transretinal 1/T1 profiles. Notably, the inner segment layer 1/T1 of SI-treated B6 mice was responsive to ALA but was unresponsive in SI-treated S6 mice. In both SI-treated strains, antioxidants improved contrast sensitivity to similar extents; antioxidants did not change acuity in either group. Retinal thicknesses were normal in both SI-treated strains at 24 hours after treatment. QUEST MRI uniquely measured severity of excessive free radical production within retinal layers of the same subject. Identifying the mechanisms underlying genetic vulnerabilities to oxidative stress is expected to help in understanding the pathogenesis of retinal degeneration.

The self-setting properties and in vitro bioactivity of tricalcium silicate.

PubMed

Zhao, Wenyuan; Wang, Junying; Zhai, Wanyin; Wang, Zheng; Chang, Jiang

2005-11-01

In this study, tricalcium silicate (Ca(3)SiO(5)), as a new promising injectable bioactive material, was employed to investigate its physical and chemical properties for an injectable bioactive cement filler. The workable Ca(3)SiO(5) pastes with a liquid to powder (L/P) ratio of 0.8--.2 mlg(-1)could be injected for 15--60 min (nozzle diameter 2.0mm). The setting process yielded cellular structures with compressive strength of 6.4--20.2 MPa after 2--28 days. The in vitro bioactivity of Ca(3)SiO(5) paste was investigated by soaking in simulated body fluid (SBF) for various periods. The result showed that the Ca(3)SiO(5) paste could induce hydroxyapatite (HA) formation and dissolve slowly in SBF. The result of indirect cytotoxicity evaluation indicated that Ca(3)SiO(5) paste had a stimulatory effect on cell growth in a certain concentration range. The exothermic process showed that Ca(3)SiO(5) had lower heat evolution rate during the hydration as compared to calcium phosphate cement (CPC). Our results indicated that Ca(3)SiO(5) paste was bioactive and dissolvable, and it is a progressive candidate for further investigation as injectable tissue repairing substitute.

Slow positron studies of hydrogen activation/passivation on SiO2/Si(100) interfaces

NASA Astrophysics Data System (ADS)

Lynn, K. G.; Asoka-Kumar, P.

The hydrogen atoms are one of the most common impurity species found in semiconductor systems owing to its large diffusivity, and are easily incorporated either in a controlled process like in ion implantation or in an uncontrolled process like the one at the fabrication stage. Hydrogen can passivate dangling bonds and dislocations in these systems and hence can be used to enhance the electrical properties. In a SiO2/Si system, hydrogen can passivate electronic states at the interface and can alter the fixed or mobile charges in the oxide layer. Since hydrogen is present in almost all of the environments of SiO2/Si wafer fabrication, the activation energy of hydrogen atoms is of paramount importance to a proper understanding of SiO2/Si based devices and has not been measured on the technologically most important Si(100) face. There are no direct, nondestructive methods available to observe hydrogen injection into the oxide layer and subsequent diffusion. The positrons are used as a 'sensitive', nondestructive probe to observe hydrogen interaction in the oxide layer and the interface region. A new way is described of characterizing the changes in the density of the interface states under a low temperature annealing using positrons.

Intravenous siRNA of brain cancer with receptor targeting and avidin-biotin technology.

PubMed

Xia, Chun-Fang; Zhang, Yufeng; Zhang, Yun; Boado, Ruben J; Pardridge, William M

2007-12-01

The effective delivery of short interfering RNA (siRNA) to brain following intravenous administration requires the development of a delivery system for transport of the siRNA across the brain capillary endothelial wall, which forms the blood-brain barrier in vivo. siRNA was delivered to brain in vivo with the combined use of a receptor-specific monoclonal antibody delivery system, and avidin-biotin technology. The siRNA was mono-biotinylated on either terminus of the sense strand, in parallel with the production of a conjugate of the targeting MAb and streptavidin. Rat glial cells (C6 or RG-2) were permanently transfected with the luciferase gene, and implanted in the brain of adult rats. Following the formation of intra-cranial tumors, the rats were treated with a single intravenous injection of 270 microg/kg of biotinylated siRNA attached to a transferrin receptor antibody via a biotin-streptavidin linker. The intravenous administration of the siRNA caused a 69-81% decrease in luciferase gene expression in the intracranial brain cancer in vivo. Brain delivery of siRNA following intravenous administration is possible with siRNAs that are targeted to brain with the combined use of receptor specific antibody delivery systems and avidin-biotin technology.

Characterization and Application of a Nose-Only Exposure Chamber for Inhalation Delivery of Liposomal Drugs and Nucleic Acids to Mice

PubMed Central

Seshadri, S.; Garbuzenko, O.B.; Han, T.; Wang, Z.; Minko, T.

2013-01-01

Abstract Background A small nose-only exposure chamber was evaluated for inhalation delivery of drug carrier systems (DCSs) to mice for the treatment of lung cancer. The chamber then was used for inhalation delivery of an anticancer drug, antisense oligonucleotides (ASO), and small interfering RNA (siRNA) directly to the cancerous lungs of mice. Methods The uniformity of particle delivery across the ports of the exposure chamber and stability of the DCS (liposomes) during continuous aerosolization by a Collison nebulizer were examined. The mean produced particle size by number was approximately 130 nm, and the mass median diameter was approximately 270 nm. The system was then used to deliver DCS containing doxorubicin (DOX) and ASO or siRNA targeted to multidrug resistance-associated protein 1 (MRP1) mRNA as suppressors of cancer cell resistance. The retention of the drug in the lungs and the effect on tumor size were compared after inhalation delivery and intravenous injection in a nu/nu mouse model of lung cancer. Results The aerosol mass across the four inhalation ports had a coefficient of variation of less than 12%, and approximately 1.4% of the nebulized mass was available for inhalation at each port. The mean size of 130 nm of liposomal DCS did not change significantly during continuous 60-min aerosolization. For inhalation delivery of DCS with DOX+ASO/siRNA, the amount of drugs available for inhalation was lower compared with intravenous injection of DOX; however, the observed lung dose and the retention time were significantly higher. The delivery of DOX+ASO/siRNA via inhalation resulted in tumor volume reduction of more than 90%, whereas only about 40% reduction was achieved after intravenous injection of DOX. Conclusions The investigated exposure system is suitable for inhalation delivery of complex DCS, and its use to deliver DCS containing anticancer drugs and resistance suppressors via inhalation offered a superior method for lung cancer treatment in mice compared with intravenous injections. PMID:23530772

Feasibility of ultrasound-guided sacroiliac joint injection considering sonoanatomic landmarks at two different levels in cadavers and patients.

PubMed

Klauser, Andrea; De Zordo, Tobias; Feuchtner, Gudrun; Sögner, Peter; Schirmer, Michael; Gruber, Johann; Sepp, Norbert; Moriggl, Bernhard

2008-11-15

Sacroiliitis is often caused by rheumatic diseases, and besides other therapeutic options, treatment consists of intraarticular injection of corticosteroids. The purpose of this study was to assess the feasibility of ultrasound (US)-guided sacroiliac joint (SI joint) injection at 2 different puncture levels in cadavers and patients when defined sonoanatomic landmarks were considered. After defining sonoanatomic landmarks, US-guided needle insertion was performed in 10 human cadavers (20 SI joints) at 2 different puncture sites. Upper level was defined at the level of the posterior sacral foramen 1 and lower level at the level of the posterior sacral foramen 2. In 10 patients with unilateral sacroiliitis, injection at the most feasible level was attempted. Computed tomography confirmed correct intraarticular needle placement in cadavers by showing the tip of the needle in the joint and intraarticular diffusion of contrast media in 16 (80%) of 20 SI joints (upper level 7 [70%] of 10; lower level 9 [90%] of 10). In all 4 cases in which needle insertion failed, intraarticular SI joint injection at the other level was successful. In patients, 100% of US-guided injections were successful (8 lower level, 2 upper level), with a mean pain relief of 8.6 after 3 months. US guidance of needle insertion into SI joints was feasible at both levels when defined sonoanatomic landmarks were used. If SI joint alterations do not allow for direct visualization of the dorsal joint space of the lower level, which is easier to access, the upper level might offer an appropriate alternative.

Spin injection into silicon in three-terminal vertical and four-terminal lateral devices with Fe/Mg/MgO/Si tunnel junctions having an ultrathin Mg insertion layer

NASA Astrophysics Data System (ADS)

Sato, Shoichi; Nakane, Ryosho; Hada, Takato; Tanaka, Masaaki

2017-12-01

We demonstrate that the spin injection/extraction efficiency is enhanced by an ultrathin Mg insertion layer (⩽2 nm) in Fe /Mg /MgO /n+-Si tunnel junctions. In diode-type vertical three-terminal devices fabricated on a Si substrate, we observe the narrower three-terminal Hanle (N-3TH) signals indicating true spin injection into Si and estimate the spin polarization in Si to be 16% when the thickness of the Mg insertion layer is 1 nm, whereas no N-3TH signal is observed without the Mg insertion. This means that the spin injection/extraction efficiency is enhanced by suppressing the formation of a magnetically dead layer at the Fe/MgO interface. We also observe clear spin transport signals, such as nonlocal Hanle signals and spin-valve signals, in a lateral four-terminal device with the same Fe /Mg /MgO /n+-Si tunnel junctions fabricated on a Si-on-insulator substrate. It is found that both the intensity and linewidth of the spin signals are affected by the geometrical effects (device geometry and size). We have derived analytical functions taking into account the device structures, including channel thickness and electrode size, and estimated important parameters: spin lifetime and spin polarization. Our analytical functions explain the experimental results very well. Our study shows the importance of suppressing a magnetically dead layer and provides a unified understanding of spin injection/detection signals in different device geometries.

Systemic delivery of siRNA by hyaluronan-functionalized calcium phosphate nanoparticles for tumor-targeted therapy

NASA Astrophysics Data System (ADS)

Qiu, Chong; Wei, Wei; Sun, Jing; Zhang, Hai-Tao; Ding, Jing-Song; Wang, Jian-Cheng; Zhang, Qiang

2016-06-01

In this study, hyaluronan (HA)-functionalized calcium phosphate nanoparticles (CaP-AHA/siRNA NPs) were developed for an injectable and targetable delivery of siRNA, which were prepared by coating the alendronate-hyaluronan graft polymer (AHA) around the surface of calcium phosphate-siRNA co-precipitates. The prepared CaP-AHA/siRNA NPs had a uniform spherical core-shell morphology with an approximate size of 170 nm and zeta potential of -12 mV. The coating of hydrophilic HA improved the physical stability of nanoparticles over one month due to the strong interactions between phosphonate and calcium. In vitro experiments demonstrated that the negatively charged CaP-AHA/siRNA NPs could effectively deliver EGFR-targeted siRNA into A549 cells through CD44-mediated endocytosis and significantly down-regulate the level of EGFR expression. Also, the internalized CaP-AHA/siRNA NPs exhibited a pH-responsive release of siRNA, indicating that the acidification of lysosomes probably facilitated the disassembling of nanoparticles and the resultant ions sharply increased the inner osmotic pressure and thus expedited the release of siRNA from late lysosomes into the cytoplasm. Furthermore, in vivo tumor therapy demonstrated that high accumulation of CaP-AHA/siEGFR NPs in tumor led to a significant tumor growth inhibition with a specific EGFR gene silencing effect after intravenous administration in nude mice xenografted with A549 tumor, along with a negligible body weight loss. These results suggested that the CaP-AHA/siRNA NPs could be an effective and safe systemic siRNA delivery system for a RNAi-based tumor targeted therapy strategy.In this study, hyaluronan (HA)-functionalized calcium phosphate nanoparticles (CaP-AHA/siRNA NPs) were developed for an injectable and targetable delivery of siRNA, which were prepared by coating the alendronate-hyaluronan graft polymer (AHA) around the surface of calcium phosphate-siRNA co-precipitates. The prepared CaP-AHA/siRNA NPs had a uniform spherical core-shell morphology with an approximate size of 170 nm and zeta potential of -12 mV. The coating of hydrophilic HA improved the physical stability of nanoparticles over one month due to the strong interactions between phosphonate and calcium. In vitro experiments demonstrated that the negatively charged CaP-AHA/siRNA NPs could effectively deliver EGFR-targeted siRNA into A549 cells through CD44-mediated endocytosis and significantly down-regulate the level of EGFR expression. Also, the internalized CaP-AHA/siRNA NPs exhibited a pH-responsive release of siRNA, indicating that the acidification of lysosomes probably facilitated the disassembling of nanoparticles and the resultant ions sharply increased the inner osmotic pressure and thus expedited the release of siRNA from late lysosomes into the cytoplasm. Furthermore, in vivo tumor therapy demonstrated that high accumulation of CaP-AHA/siEGFR NPs in tumor led to a significant tumor growth inhibition with a specific EGFR gene silencing effect after intravenous administration in nude mice xenografted with A549 tumor, along with a negligible body weight loss. These results suggested that the CaP-AHA/siRNA NPs could be an effective and safe systemic siRNA delivery system for a RNAi-based tumor targeted therapy strategy. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr04034a

A simple and effective approach to prepare injectable macroporous calcium phosphate cement for bone repair: Syringe-foaming using a viscous hydrophilic polymeric solution.

PubMed

Zhang, Jingtao; Liu, Weizhen; Gauthier, Olivier; Sourice, Sophie; Pilet, Paul; Rethore, Gildas; Khairoun, Khalid; Bouler, Jean-Michel; Tancret, Franck; Weiss, Pierre

2016-02-01

In this study, we propose a simple and effective strategy to prepare injectable macroporous calcium phosphate cements (CPCs) by syringe-foaming via hydrophilic viscous polymeric solution, such as using silanized-hydroxypropyl methylcellulose (Si-HPMC) as a foaming agent. The Si-HPMC foamed CPCs demonstrate excellent handling properties such as injectability and cohesion. After hardening the foamed CPCs possess hierarchical macropores and their mechanical properties (Young's modulus and compressive strength) are comparable to those of cancellous bone. Moreover, a preliminary in vivo study in the distal femoral sites of rabbits was conducted to evaluate the biofunctionality of this injectable macroporous CPC. The evidence of newly formed bone in the central zone of implantation site indicates the feasibility and effectiveness of this foaming strategy that will have to be optimized by further extensive animal experiments. A major challenge in the design of biomaterial-based injectable bone substitutes is the development of cohesive, macroporous and self-setting calcium phosphate cement (CPC) that enables rapid cell invasion with adequate initial mechanical properties without the use of complex processing and additives. Thus, we propose a simple and effective strategy to prepare injectable macroporous CPCs through syringe-foaming using a hydrophilic viscous polymeric solution (silanized-hydroxypropyl methylcellulose, Si-HPMC) as a foaming agent, that simultaneously meets all the aforementioned aims. Evidence from our in vivo studies shows the existence of newly formed bone within the implantation site, indicating the feasibility and effectiveness of this foaming strategy, which could be used in various CPC systems using other hydrophilic viscous polymeric solutions. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Inhibition of Hepatitis C Virus Replication by Intracellular Delivery of Multiple siRNAs by Nanosomes

PubMed Central

Chandra, Partha K; Kundu, Anup K; Hazari, Sidhartha; Chandra, Sruti; Bao, Lili; Ooms, Tara; Morris, Gilbert F; Wu, Tong; Mandal, Tarun K; Dash, Srikanta

2012-01-01

Sustained antiviral responses of chronic hepatitis C virus (HCV) infection have improved recently by the use of direct-acting antiviral agents along with interferon (IFN)-α and ribavirin. However, the emergence of drug-resistant variants is expected to be a major problem. We describe here a novel combinatorial small interfering RNA (siRNA) nanosome-based antiviral approach to clear HCV infection. Multiple siRNAs targeted to the highly conserved 5′-untranslated region (UTR) of the HCV genome were synthesized and encapsulated into lipid nanoparticles called nanosomes. We show that siRNA can be repeatedly delivered to 100% of cells in culture using nanosomes without toxicity. Six siRNAs dramatically reduced HCV replication in both the replicon and infectious cell culture model. Repeated treatments with two siRNAs were better than a single siRNA treatment in minimizing the development of an escape mutant, resulting in rapid inhibition of viral replication. Systemic administration of combinatorial siRNA-nanosomes is well tolerated in BALB/c mice without liver injury or histological toxicity. As a proof-of-principle, we showed that systemic injections of siRNA nanosomes significantly reduced HCV replication in a liver tumor-xenotransplant mouse model of HCV. Our results indicate that systemic delivery of combinatorial siRNA nanosomes can be used to minimize the development of escape mutants and inhibition of HCV infection. PMID:22617108

Overview of the Helicity Injected Torus (HIT) Program

NASA Astrophysics Data System (ADS)

Redd, A. J.; Jarboe, T. R.; Hamp, W. T.; Nelson, B. A.; O'Neill, R. G.; Sieck, P. E.; Smith, R. J.; Sutphin, G. L.; Wrobel, J. S.

2007-06-01

The Helicity Injected Torus with Steady Inductive Helicity Injection (HIT-SI) consists of a "bowtie"-shaped axisymmetric confinement region, with two half-torus helicity injectors mounted on each side of the axisymmetric flux conserver [Sieck et al, IEEE Trans. Plasma Sci., v.33, p.723 (2005); Jarboe, Fusion Technology, v.36, p.85 (1999)]. Current and flux are driven sinusoidally with time in each injector, with the goal of generating and sustaining an axisymmetric spheromak in the main confinement region. Improvements in machine conditioning have enabled systematic study of HIT-SI discharges with significant toroidal current ITOR, including cases in which this current ITOR switches sign one or more times during the discharge. Statistical studies of all HIT-SI discharges to date demonstrate a minimum injected power to form significant ITOR, and that the maximum ITOR scales approximately linearly with the total injected power.

Injection molding of silicon carbide capable of being sintered without pressure

NASA Technical Reports Server (NTRS)

Muller-Zell, A.; Schwarzmeier, R.

1984-01-01

The most suitable SiC mass for injection molding of SiC articles (for subsequent pressureless sintering) consisted of beta SiC 84, a wax mixture 8, and polyethylene or polystyrene 8 parts. The most effective method for adding the binders was by dissolving them in a solvent and subsequent evaporation. The sequence of component addition was significant, and all parameters were optimized together rather than individually.

Dissolution of Si in Molten Al with Gas Injection

NASA Astrophysics Data System (ADS)

Seyed Ahmadi, Mehran

Silicon is an essential component of many aluminum alloys, as it imparts a range of desirable characteristics. However, there are considerable practical difficulties in dissolving solid Si in molten Al, because the dissolution process is slow, resulting in material and energy losses. It is thus essential to examine Si dissolution in molten Al, to identify means of accelerating the process. This thesis presents an experimental study of the effect of Si purity, bath temperature, fluid flow conditions, and gas stirring on the dissolution of Si in molten Al, plus the results of physical and numerical modeling of the flow to corroborate the experimental results. The dissolution experiments were conducted in a revolving liquid metal tank to generate a bulk velocity, and gas was introduced into the melt using top lance injection. Cylindrical Si specimens were immersed into molten Al for fixed durations, and upon removal the dissolved Si was measured. The shape and trajectory of injected bubbles were examined by means of auxiliary water experiments and video recordings of the molten Al free surface. The gas-agitated liquid was simulated using the commercial software FLOW-3D. The simulation results provide insights into bubble dynamics and offer estimates of the fluctuating velocities within the Al bath. The experimental results indicate that the dissolution rate of Si increases in tandem with the melt temperature and bulk velocity. A higher bath temperature increases the solubility of Si at the solid/liquid interface, resulting in a greater driving force for mass transfer, and a higher liquid velocity decreases the resistance to mass transfer via a thinner mass boundary layer. Impurities (with lower diffusion coefficients) in the form of inclusions obstruct the dissolution of the Si main matrix. Finally, dissolution rate enhancement was observed by gas agitation. It is postulated that the bubble-induced fluctuating velocities disturb the mass boundary layer, which increases the mass transfer rate. Correlations derived for mass transfer from solids in liquids under various operating conditions were applied to the Al--Si system. A new correlation for combined natural and forced convection mass transfer from vertical cylinders in cross flow is presented, and a modification is proposed to take into account free stream turbulence in a correlation for forced convection mass transfer from vertical cylinders in cross flow.

Electrical detection of nuclear spin-echo signals in an electron spin injection system

NASA Astrophysics Data System (ADS)

Lin, Zhichao; Rasly, Mahmoud; Uemura, Tetsuya

2017-06-01

We demonstrated spin echoes of nuclear spins in a spin injection device with a highly polarized spin source by nuclear magnetic resonance (NMR). Efficient spin injection into GaAs from a half-metallic spin source of Co2MnSi enabled efficient dynamic nuclear polarization (DNP) and sensitive detection of NMR signals even at a low magnetic field of ˜0.1 T and a relatively high temperature of 4.2 K. The intrinsic coherence time T2 of 69Ga nuclear spins was evaluated from the spin-echo signals. The relation between T2 and the decay time of the Rabi oscillation suggests that the inhomogeneous effects in our system are not obvious. This study provides an all-electrical NMR system for nuclear-spin-based qubits.

Experimental application of thermosensitive paramagnetic liposomes for monitoring magnetic resonance imaging guided thermal ablation.

PubMed

Frich, Lars; Bjørnerud, Atle; Fossheim, Sigrid; Tillung, Terje; Gladhaug, Ivar

2004-12-01

The use of a liposomal paramagnetic agent with a T(1)-relaxivity that increases markedly at temperatures above the phase transition temperature (T(m)) of the liposomal membrane was evaluated during magnetic resonance imaging (MRI) guided hyperthermia ablation. A neodymium-yttrium aluminum garnet (Nd-YAG) laser unit and a radiofrequency ablation system were used for tissue ablation in eight rabbit livers in vivo. One ablation was made in each animal prior to administration of the liposomal agent. Liposomes with a T(m) of 57 degrees C containing gadodiamide (GdDTPA-BMA) were injected iv, and two additional ablations were performed. T(1)-weighted scans were performed in heated tissue, after tissue temperature had normalized, and 15-20 min after normalization of tissue temperature. Increase in signal intensity (DeltaSI) for ablations prior to injection of the agent was 13.0% (SD = 5.7) for the laser group and 9.1% (SD = 7.9) for the radiofrequency group. Signal intensity after administration of the agent unrelated to heating was not statistically significant (DeltaSI = 1.4%, P = 0.35). For ablations made after injection of the agent, a significant increase was found in the laser (DeltaSI = 34.5%, SD = 11.9) and radiofrequency group (DeltaSI = 21.6%, SD = 22.7). The persistent signal enhancement found in areas exposed to a temperature above the threshold temperature above T(m) allows thermal monitoring of MRI guided thermal ablation. (c) 2004 Wiley-Liss, Inc.

Hot-electron-induced hydrogen redistribution and defect generation in metal-oxide-semiconductor capacitors

NASA Astrophysics Data System (ADS)

Buchanan, D. A.; Marwick, A. D.; Dimaria, D. J.; Dori, L.

1994-09-01

Redistribution of hydrogen caused by hot-electron injection has been studied by hydrogen depth profiling with N-15 nuclear reaction analysis and electrical methods. Internal photoemission and Fowler-Nordheim injection were used for electron injection into large Al-gate and polysilicon-gate capacitors, respectively. A hydrogen-rich layer (about 10(exp 15) atoms/sq cm) observed at the Al/SiO2 interface was found to serve as the source of hydrogen during the hot-electron stress. A small fraction of the hydrogen released from this layer was found to be retrapped near the Si/SiO2 interface for large electron fluences in the Al-gate samples. Within the limit of detectability, about 10(exp 14)/sq cm, no hydrogen was measured using nuclear reaction analysis in the polysilicon-gate samples. The buildup of hydrogen at the Si/SiO2 interface exhibits a threshold at about 1 MV/cm, consistent with the threshold for electron heating in SiO2. In the 'wet' SiO2 films with purposely introduced excess hydrogen, the rate of hydrogen buildup at the Si/SiO2 interface is found to be significantly greater than that found in the 'dry' films. During electron injection, hydrogen redistribution was also confirmed via the deactivation of boron dopant in the silicon substrate. The generation rates of interface states, neutral electron traps, and anomalous positive charge are found to increase with increasing hydrogen buildup in the substrate and the initial hydrogen concentration in the film. It is concluded that the generation of defects is preceded by the hot-electron-induced release and transport of atomic hydrogen and it is the chemical reaction of this species within the metal-oxide-semiconductor structure that generates the electrically active defects.

Color Doppler Ultrasound and Gamma Imaging of Intratumorally Injected 500 nm Iron-Silica Nanoshells

PubMed Central

Liberman, Alexander; Wu, Zhe; Barback, Christopher V.; Viveros, Robert; Blair, Sarah L.; Ellies, Lesley G.; Vera, David R.; Mattrey, Robert F.; Kummel, Andrew C.; Trogler, William C.

2013-01-01

Perfluoropentane gas filled iron-silica nanoshells have been developed as stationary ultrasound contrast agents for marking tumors to guide surgical resection. It is critical to establish their long term imaging efficacy, as well as biodistribution. This work shows that 500 nm Fe-SiO2 nanoshells can be imaged by color Doppler ultrasound over the course of 10 days in Py8119 tumor bearing mice. The 500 nm non-biodegradable SiO2 and biodegradable Fe-SiO2 nanoshells were functionalized with diethylenetriamine pentaacetic acid (DTPA) ligand and radiolabeled with 111In3+ for biodistribution studies in nu/nu mice. The majority of radioactivity was detected in the liver and kidneys following intravenous (IV) administration of nanoshells to healthy animals. By contrast, after nanoshells were injected intratumorally, most of the radioactivity remained at the injection site; however, some nanoshells escaped into circulation and were distributed similarly as those given intravenously. For intratumoral delivery of nanoshells and IV delivery to healthy animals, little difference was seen between the biodistribution of SiO2 and biodegradable Fe-SiO2 nanoshells. However, when nanoshells were administered IV to tumor bearing mice, a significant increase was observed in liver accumulation of SiO2 nanoshells relative to biodegradable Fe-SiO2 nanoshells. Both SiO2 and Fe-SiO2 nanoshells accumulate passively in proportion to tumor mass, during intravenous delivery of nanoshells. This is the first report of the biodistribution following intratumoral injection of any biodegradable silica particle, as well as the first report demonstrating the utility of DTPA-111In labeling for studying silica nanoparticle biodistributions. PMID:23802554

Silicon Carbide (SiC) MOSFET-based Full-Bridge for Fusion Science Applications

NASA Astrophysics Data System (ADS)

Ziemba, Timothy; Miller, Kenneth; Prager, James; Picard, Julian; Hashim, Akel

2014-10-01

Switching power amplifiers (SPAs) have a wide variety of applications within the fusion science community, including feedback and control systems for dynamic plasma stabilization in tokamaks, inductive and arc plasma sources, Radio Frequency (RF) helicity and flux injection, RF plasma heating and current drive schemes, ion beam generation, and RF pre-ionizer systems. SiC MOSFETs offer many advantages over IGBTs including lower drive energy requirements, lower conduction and switching losses, and higher switching frequency capabilities. When comparing SiC and traditional silicon-based MOSFETs, SiC MOSFETs provide higher current carrying capability allowing for smaller package weights and sizes and lower operating temperature. Eagle Harbor Technologies (EHT) is designing, constructing, and testing a SiC MOSFET-based full-bridge SPA. EHT will leverage the proprietary gate drive technology previously developed with the support of a DOE SBIR, which will enable fast, efficient switching in a small form factor. The primary goal is to develop a SiC MOSFET-based SPA for fusion science applications. Work supported in part by the DOE under Contract Number DE-SC0011907.

Silencing of p53 RNA through transarterial delivery ameliorates renal tubular injury and downregulates GSK-3β expression after ischemia-reperfusion injury.

PubMed

Fujino, Takayuki; Muhib, Sharifi; Sato, Nobuyuki; Hasebe, Naoyuki

2013-12-01

p53, a pivotal protein in the apoptotic pathway, has been identified as a mediator of transcriptional responses to ischemia-reperfusion (IR) injury. The characteristics and functional significance of the p53 response in vivo are largely unknown in IR-induced kidney injury. Therapeutic opportunities of delivering small interfering RNA (siRNA) via venous injection have gained recognition; however, systemic adverse effects of siRNA therapy should be considered. To prevent IR-induced kidney injury, we tested the efficacy of transarterial administration of siRNA targeting p53 (p53 siRNA). Female C57BL/6 mice underwent unilateral renal artery ischemia for 30 min, followed by reperfusion. siRNA experiments utilized short hairpin (sh) RNA plasmid-based approaches. Transfection of shRNA was performed using cationic polymer transfection reagent. Injection of synthetic p53 shRNA into the left renal artery just after ischemia improved tubular injury, apoptosis, and the swelling of mitochondria in cells of the thick ascending limb of Henle (mTALH) at the outer medullary regions. Staining of upregulated p53 was colocalized with the inducible expression of glycogen synthase kinase-3β (GSK-3β) at mTALH after IR injury. p53 shRNA inhibited GSK-3β expression and restored β-catenin expression at mTALH. For IR-induced kidney injury, transarterial delivery of p53 siRNA is an effective pharmacological intervention. Targeting siRNA to p53 leads to an attenuation of apoptosis and mitochondrial damage through the downregulation of GSK-3β expression and upregulation of β-catenin. Local delivery of vectors such as p53 siRNA through a transaortic catheter is clinically useful in reducing the adverse effect of siRNA-related therapy.

Charge Transfer from Carbon Nanotubes to Silicon in Flexible Carbon Nanotube/Silicon Solar Cells

DOE PAGES

Li, Xiaokai; Mariano, Marina; McMillon-Brown, Lyndsey; ...

2017-11-10

Mechanical fragility and insufficient light absorption are two major challenges for thin flexible crystalline Si-based solar cells. Flexible hybrid single-walled carbon nanotube (SWNT)/Si solar cells are demonstrated by applying scalable room-temperature processes for the fabrication of solar-cell components (e.g., preparation of SWNT thin films and SWNT/Si p–n junctions). The flexible SWNT/Si solar cells present an intrinsic efficiency ≈7.5% without any additional light-trapping structures. By using these solar cells as model systems, the charge transport mechanisms at the SWNT/Si interface are investigated using femtosecond transient absorption. Although primary photon absorption occurs in Si, transient absorption measurements show that SWNTs also generatemore » and inject excited charge carriers to Si. Such effects can be tuned by controlling the thickness of the SWNTs. Thus, findings from this study could open a new pathway for designing and improving the efficiency of photocarrier generation and absorption for high-performance ultrathin hybrid SWNT/Si solar cells.« less

Charge Transfer from Carbon Nanotubes to Silicon in Flexible Carbon Nanotube/Silicon Solar Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Xiaokai; Mariano, Marina; McMillon-Brown, Lyndsey

Mechanical fragility and insufficient light absorption are two major challenges for thin flexible crystalline Si-based solar cells. Flexible hybrid single-walled carbon nanotube (SWNT)/Si solar cells are demonstrated by applying scalable room-temperature processes for the fabrication of solar-cell components (e.g., preparation of SWNT thin films and SWNT/Si p–n junctions). The flexible SWNT/Si solar cells present an intrinsic efficiency ≈7.5% without any additional light-trapping structures. By using these solar cells as model systems, the charge transport mechanisms at the SWNT/Si interface are investigated using femtosecond transient absorption. Although primary photon absorption occurs in Si, transient absorption measurements show that SWNTs also generatemore » and inject excited charge carriers to Si. Such effects can be tuned by controlling the thickness of the SWNTs. Thus, findings from this study could open a new pathway for designing and improving the efficiency of photocarrier generation and absorption for high-performance ultrathin hybrid SWNT/Si solar cells.« less

229 nm UV LEDs on aluminum nitride single crystal substrates using p-type silicon for increased hole injection

NASA Astrophysics Data System (ADS)

Liu, Dong; Cho, Sang June; Park, Jeongpil; Seo, Jung-Hun; Dalmau, Rafael; Zhao, Deyin; Kim, Kwangeun; Gong, Jiarui; Kim, Munho; Lee, In-Kyu; Albrecht, John D.; Zhou, Weidong; Moody, Baxter; Ma, Zhenqiang

2018-02-01

AlGaN based 229 nm light emitting diodes (LEDs), employing p-type Si to significantly increase hole injection, were fabricated on single crystal bulk aluminum nitride (AlN) substrates. Nitride heterostructures were epitaxially deposited by organometallic vapor phase epitaxy and inherit the low dislocation density of the native substrate. Following epitaxy, a p-Si layer is bonded to the heterostructure. LEDs were characterized both electrically and optically. Owing to the low defect density films, large concentration of holes from p-Si, and efficient hole injection, no efficiency droop was observed up to a current density of 76 A/cm2 under continuous wave operation and without external thermal management. An optical output power of 160 μW was obtained with the corresponding external quantum efficiency of 0.03%. This study demonstrates that by adopting p-type Si nanomembrane contacts as a hole injector, practical levels of hole injection can be realized in UV light-emitting diodes with very high Al composition AlGaN quantum wells, enabling emission wavelengths and power levels that were previously inaccessible using traditional p-i-n structures with poor hole injection efficiency.

HIT-SI Injector Voltage Measurements Using Injector Langmuir Probes

NASA Astrophysics Data System (ADS)

Aboul Hosn, Rabih; Smith, Roger; Jarboe, Thomas

2006-10-01

A pair of Langmuir probe arrays have been designed and built to measure floating potentials of the plasma at the injector mouth of the HIT-SI device. The Helicity Injected Torus using Steady Inductive Helicity Injection (HIT-SI) [1,2] is a ``bow tie'' spheromak using an electrodeless formation and sustainment concept. HIT-SI is powered by two inductive helicity injectors operated in quadrature to maintain a constant helicity injection rate. The electric probes consist of an array of four floating potential Langmuir probes measuring the voltage distribution in each injector from the shell to midpoint of the injector mouth. The probe measurements combine to determine the part of the injector loop voltage driving the n = 0 spheromak equilibrium region. Preliminary data suggest the spheromak voltage is the loop voltage minus the nearly constant injector voltage of 150-180 volts. These probe data will be used to calculate the helicity decay time of the spheromak. [1] T. R. Jarboe. Steady inductive helicity injection and its application to a high-beta spheromak. Fusion Technology, 36(1):85--91, July 1999. [2] P.E.Sieck et al., ``Demonstration of Steady Inductive Helicity Injection'', Nuc. Fusion, in press (2006).

Acupuncture at SI5 attenuates morphine seeking behavior after extinction.

PubMed

Lee, Bong Hyo; Ma, Jeong Hun; In, Sunghyun; Kim, Hee Young; Yoon, Seong Shoon; Jang, Eun Young; Yang, Chae Ha

2012-10-31

Our previous studies have shown that acupuncture attenuates morphine self-administration and sensitization behavior as well as withdrawal signs. The present study was designed to investigate the role of acupuncture in the reinstatement of morphine seeking. Male Sprague-Dawley rats weighing 270-300 g were subjected to intravenous catheterization after food training. The animals were trained to self-administer morphine (1.0mg/kg, 3 weeks), followed by extinction (1 week). Extinction conditions were introduced by substituting saline for morphine. The rats were then tested for reinstatement of morphine self-administration by a priming injection of morphine (0.25mg/kg). To see whether acupuncture can reduce morphine reinstatement, acupuncture was performed at SI5 or LI5 for 1 min immediately before a morphine injection. To further test the involvement of gamma aminobutyric acid (GABA) receptors in acupuncture effects, GABA receptor antagonists were injected before acupuncture. In the present results, acupuncture at SI5, but not at control acupoint LI5 attenuated the reinstatement of morphine seeking behavior, which was blocked by the GABA receptor antagonists. It suggests that acupuncture can reduce the reinstatement of morphine seeking, possibly due to the mediation of GABA receptor system. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Spin-injection into epitaxial graphene on silicon carbide

NASA Astrophysics Data System (ADS)

Konishi, Keita; Cui, Zhixin; Hiraki, Takahiro; Yoh, Kanji

2013-09-01

We have studied the spin-injection properties in epitaxial graphene on SiC. The ferromagnetic metal (FM) electrodes were composed of a tunnel barrier layer AlOx (14 Å) and a ferromagnetic Co (600 Å) layer. We have successfully observed the clear resistance peaks indicating spin-injection both in the "local" and "non-local" spin measurement set-ups at low temperatures. We estimate spin-injection rate of 1% based on "non-local" measurement and 1.6% based on local measurements. Spin-injection rate of multilayer graphene by mechanical exfoliation method was twice as high as single layer graphene on SiC based on "local" measurement.

Injectable Ceramic Microcast Silicon Carbonitride (SiCN) Microelectromechanical System (MEMS) for Extreme Temperature Environments with Extension: Micro Packages for Nano-Devices

DTIC Science & Technology

2004-01-01

pyrolyzed to produce the ceramic (SiCN) parts, or they may be retained in the polymeric state and used as high-temperature polymer /glass MEMS devices. Two...structure and the SU8 /wafer is weak due to the Teflon coating. (j) A free standing polymer structure results. The structure is then crosslinked and... polymer . Further efforts are necessary to identify the least damaging rinsing chemicals, that is, chemicals which would not contaminate polymerized

Methods of Si based ceramic components volatilization control in a gas turbine engine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia-Crespo, Andres Jose; Delvaux, John; Dion Ouellet, Noemie

A method of controlling volatilization of silicon based components in a gas turbine engine includes measuring, estimating and/or predicting a variable related to operation of the gas turbine engine; correlating the variable to determine an amount of silicon to control volatilization of the silicon based components in the gas turbine engine; and injecting silicon into the gas turbine engine to control volatilization of the silicon based components. A gas turbine with a compressor, combustion system, turbine section and silicon injection system may be controlled by a controller that implements the control method.

Charge injection and discharging of Si nanocrystals and arrays by atomic force microscopy

NASA Technical Reports Server (NTRS)

Boer, E.; Ostraat, M.; Brongersma, M. L.; Flagan, R. C.; Atwater, H. A.

2000-01-01

Charge injection and storage in dense arrays of silicon nanocrystals in SiO(sub 2) is a critical aspect of the performance of potential nanocrystal flash memory structures. The ultimate goal for this class of devices is few-or single- electron storage in a small number of nanocrystal elements.

Improved silicon carbide for advanced heat engines. I - Process development for injection molding

NASA Technical Reports Server (NTRS)

Whalen, Thomas J.; Trela, Walter

1989-01-01

Alternate processing methods have been investigated as a means of improving the mechanical properties of injection-molded SiC. Various mixing processes (dry, high-sheer, and fluid) were evaluated along with the morphology and particle size of the starting beta-SiC powder. Statistically-designed experiments were used to determine significant effects and interactions of variables in the mixing, injection molding, and binder removal process steps. Improvements in mechanical strength can be correlated with the reduction in flaw size observed in the injection molded green bodies obtained with improved processing methods.

Specific beta1-adrenergic receptor silencing with small interfering RNA lowers high blood pressure and improves cardiac function in myocardial ischemia.

PubMed

Arnold, Anne-Sophie; Tang, Yao Liang; Qian, Keping; Shen, Leping; Valencia, Valery; Phillips, Michael Ian; Zhang, Yuan Clare

2007-01-01

Beta-blockers are widely used and effective for treating hypertension, acute myocardial infarction (MI) and heart failure, but they present side-effects mainly due to antagonism of beta2-adrenergic receptor (AR). Currently available beta-blockers are at best selective but not specific for beta1 or beta2-AR. To specifically inhibit the expression of the beta1-AR, we developed a small interfering RNA (siRNA) targeted to beta1-AR. Three different sequences of beta1 siRNA were delivered into C6-2B cells with 90% efficiency. One of the three sequences reduced the level of beta1-AR mRNA by 70%. The siRNA was highly specific for beta1-AR inhibition with no overlap with beta2-AR. To test this in vivo, systemic injection of beta1 siRNA complexed with liposomes resulted in efficient delivery into the heart, lung, kidney and liver, and effectively reduced beta1-AR expression in the heart without altering beta2-AR. beta1 siRNA significantly lowered blood pressure of spontaneously hypertensive rats (SHR) for at least 12 days and reduced cardiac hypertrophy following a single injection. Pretreatment with beta1 siRNA 3 days before induction of MI in Wistar rats significantly improved cardiac function, as demonstrated by dP/dt and electrocardiogram following the MI. The protective mechanism involved reduction of cardiomyocyte apoptosis in the beta1 siRNA-treated hearts. The present study demonstrates the possibility of using siRNA for treating cardiovascular diseases and may represent a novel beta-blocker specific for beta1-AR.

Distinct roles for RDE-1 and RDE-4 during RNA interference in Caenorhabditis elegans.

PubMed

Parrish, S; Fire, A

2001-10-01

RNA interference (RNAi) is a cellular defense mechanism that uses double-stranded RNA (dsRNA) as a sequence-specific trigger to guide the degradation of homologous single-stranded RNAs. RNAi is a multistep process involving several proteins and at least one type of RNA intermediate, a population of small 21-25 nt RNAs (called siRNAs) that are initially derived from cleavage of the dsRNA trigger. Genetic screens in Caenorhabditis elegans have identified numerous mutations that cause partial or complete loss of RNAi. In this work, we analyzed cleavage of injected dsRNA to produce the initial siRNA population in animals mutant for rde-1 and rde-4, two genes that are essential for RNAi but that are not required for organismal viability or fertility. Our results suggest distinct roles for RDE-1 and RDE-4 in the interference process. Although null mutants lacking rde-1 show no phenotypic response to dsRNA, the amount of siRNAs generated from an injected dsRNA trigger was comparable to that of wild-type. By contrast, mutations in rde-4 substantially reduced the population of siRNAs derived from an injected dsRNA trigger. Injection of chemically synthesized 24- or 25-nt siRNAs could circumvent RNAi resistance in rde-4 mutants, whereas no bypass was observed in rde-1 mutants. These results support a model in which RDE-4 is involved before or during production of siRNAs, whereas RDE-1 acts after the siRNAs have been formed.

Distinct roles for RDE-1 and RDE-4 during RNA interference in Caenorhabditis elegans.

PubMed Central

Parrish, S; Fire, A

2001-01-01

RNA interference (RNAi) is a cellular defense mechanism that uses double-stranded RNA (dsRNA) as a sequence-specific trigger to guide the degradation of homologous single-stranded RNAs. RNAi is a multistep process involving several proteins and at least one type of RNA intermediate, a population of small 21-25 nt RNAs (called siRNAs) that are initially derived from cleavage of the dsRNA trigger. Genetic screens in Caenorhabditis elegans have identified numerous mutations that cause partial or complete loss of RNAi. In this work, we analyzed cleavage of injected dsRNA to produce the initial siRNA population in animals mutant for rde-1 and rde-4, two genes that are essential for RNAi but that are not required for organismal viability or fertility. Our results suggest distinct roles for RDE-1 and RDE-4 in the interference process. Although null mutants lacking rde-1 show no phenotypic response to dsRNA, the amount of siRNAs generated from an injected dsRNA trigger was comparable to that of wild-type. By contrast, mutations in rde-4 substantially reduced the population of siRNAs derived from an injected dsRNA trigger. Injection of chemically synthesized 24- or 25-nt siRNAs could circumvent RNAi resistance in rde-4 mutants, whereas no bypass was observed in rde-1 mutants. These results support a model in which RDE-4 is involved before or during production of siRNAs, whereas RDE-1 acts after the siRNAs have been formed. PMID:11680844

Study Trapped Charge Distribution in P-Channel Silicon-Oxide-Nitride-Oxide-Silicon Memory Device Using Dynamic Programming Scheme

NASA Astrophysics Data System (ADS)

Li, Fu-Hai; Chiu, Yung-Yueh; Lee, Yen-Hui; Chang, Ru-Wei; Yang, Bo-Jun; Sun, Wein-Town; Lee, Eric; Kuo, Chao-Wei; Shirota, Riichiro

2013-04-01

In this study, we precisely investigate the charge distribution in SiN layer by dynamic programming of channel hot hole induced hot electron injection (CHHIHE) in p-channel silicon-oxide-nitride-oxide-silicon (SONOS) memory device. In the dynamic programming scheme, gate voltage is increased as a staircase with fixed step amplitude, which can prohibits the injection of holes in SiN layer. Three-dimensional device simulation is calibrated and is compared with the measured programming characteristics. It is found, for the first time, that the hot electron injection point quickly traverses from drain to source side synchronizing to the expansion of charged area in SiN layer. As a result, the injected charges quickly spread over on the almost whole channel area uniformly during a short programming period, which will afford large tolerance against lateral trapped charge diffusion by baking.

Ocular silicon distribution and clearance following intravitreal injection of porous silicon microparticles

PubMed Central

Nieto, Alejandra; Hou, Huiyuan; Sailor, Michael J.; Freeman, William R.; Cheng, Lingyun

2013-01-01

Porous silicon (pSi) microparticles have been investigated for intravitreal drug delivery and demonstrated good biocompatibility. With the appropriate surface chemistry, pSi can reside in vitreous for months or longer. However, ocular distribution and clearance pathway of its degradation product, silicic acid, are not well understood. In the current study, rabbit ocular tissue was collected at different time point following fresh pSi (day 1, 5, 9, 16, and 21) or oxidized pSi (day 3, 7, 14, 21, and 35) intravitreal injection. In addition, dual-probe simultaneous microdialysis of aqueous and vitreous humor was performed following a bolus intravitreal injection of 0.25 mL silicic acid (150 μg/mL) and six consecutive microdialysates were collected every 20 min. Silicon was quantified from the samples using inductively coupled plasma-optical emission spectroscopy. The study showed that following the intravitreal injection of oxidized pSi, free silicon was consistently higher in the aqueous than in the retina (8.1 ± 6.5 vs. 3.4 ± 3.9 μg/mL, p = 0.0031). The area under the concentration-time curve (AUC) of the retina was only about 24% that of the aqueous. The mean residence time was 16 days for aqueous, 13 days for vitreous, 6 days for retina, and 18 days for plasma. Similarly, following intravitreal fresh pSi, free silicon was also found higher in aqueous than in retina (7 ± 4.7 vs. 3.4 ± 4.1 μg/mL, p = 0.014). The AUC for the retina was about 50% of the AUC for the aqueous. The microdialysis revealed the terminal half-life of free silicon in the aqueous was 30 min and 92 min in the vitreous; the AUC for aqueous accounted for 38% of the AUC for vitreous. Our studies indicate that aqueous humor is a significant pathway for silicon egress from the eye following intravitreal injection of pSi crystals. PMID:24036388

Design of a peptide-based vector, PepFect6, for efficient delivery of siRNA in cell culture and systemically in vivo

PubMed Central

EL Andaloussi, Samir; Lehto, Taavi; Mäger, Imre; Rosenthal-Aizman, Katri; Oprea, Iulian I.; Simonson, Oscar E.; Sork, Helena; Ezzat, Kariem; Copolovici, Dana M.; Kurrikoff, Kaido; Viola, Joana R.; Zaghloul, Eman M.; Sillard, Rannar; Johansson, Henrik J.; Said Hassane, Fatouma; Guterstam, Peter; Suhorutšenko, Julia; Moreno, Pedro M. D.; Oskolkov, Nikita; Hälldin, Jonas; Tedebark, Ulf; Metspalu, Andres; Lebleu, Bernard; Lehtiö, Janne; Smith, C. I. Edvard; Langel, Ülo

2011-01-01

While small interfering RNAs (siRNAs) have been rapidly appreciated to silence genes, efficient and non-toxic vectors for primary cells and for systemic in vivo delivery are lacking. Several siRNA-delivery vehicles, including cell-penetrating peptides (CPPs), have been developed but their utility is often restricted by entrapment following endocytosis. Hence, developing CPPs that promote endosomal escape is a prerequisite for successful siRNA implementation. We here present a novel CPP, PepFect 6 (PF6), comprising the previously reported stearyl-TP10 peptide, having pH titratable trifluoromethylquinoline moieties covalently incorporated to facilitate endosomal release. Stable PF6/siRNA nanoparticles enter entire cell populations and rapidly promote endosomal escape, resulting in robust RNAi responses in various cell types (including primary cells), with minimal associated transcriptomic or proteomic changes. Furthermore, PF6-mediated delivery is independent of cell confluence and, in most cases, not significantly hampered by serum proteins. Finally, these nanoparticles promote strong RNAi responses in different organs following systemic delivery in mice without any associated toxicity. Strikingly, similar knockdown in liver is achieved by PF6/siRNA nanoparticles and siRNA injected by hydrodynamic infusion, a golden standard technique for liver transfection. These results imply that the peptide, in addition to having utility for RNAi screens in vitro, displays therapeutic potential. PMID:21245043

Reduction of plasma density in the Helicity Injected Torus with Steady Inductance experiment by using a helicon pre-ionization source.

PubMed

Hossack, Aaron C; Firman, Taylor; Jarboe, Thomas R; Prager, James R; Victor, Brian S; Wrobel, Jonathan S; Ziemba, Timothy

2013-10-01

A helicon based pre-ionization source has been developed and installed on the Helicity Injected Torus with Steady Inductance (HIT-SI) spheromak. The source initiates plasma breakdown by injecting impurity-free, unmagnetized plasma into the HIT-SI confinement volume. Typical helium spheromaks have electron density reduced from (2-3) × 10(19) m(-3) to 1 × 10(19) m(-3). Deuterium spheromak formation is possible with density as low as 2 × 10(18) m(-3). The source also enables HIT-SI to be operated with only one helicity injector at injector frequencies above 14.5 kHz. A theory explaining the physical mechanism driving the reduction of breakdown density is presented.

Metal/oxide/semiconductor interface investigated by monoenergetic positrons

NASA Astrophysics Data System (ADS)

Uedono, A.; Tanigawa, S.; Ohji, Y.

1988-10-01

Variable-energy positron-beam studies have been carried out for the first time on a metal/oxide/semiconductor (MOS) structure of polycrystalline Si/SiO 2/Si-substrate. We were successful in collecting injected positrons at the SiO 2/Si interface by the application of an electric field between the MOS electrodes.

A graphene solution to conductivity mismatch: spin injection from ferromagnetic metal/graphene tunnel contacts into silicon

NASA Astrophysics Data System (ADS)

van't Erve, Olaf

2014-03-01

New paradigms for spin-based devices, such as spin-FETs and reconfigurable logic, have been proposed and modeled. These devices rely on electron spin being injected, transported, manipulated and detected in a semiconductor channel. This work is the first demonstration on how a single layer of graphene can be used as a low resistance tunnel barrier solution for electrical spin injection into Silicon at room temperature. We will show that a FM metal / monolayer graphene contact serves as a spin-polarized tunnel barrier which successfully circumvents the classic metal / semiconductor conductivity mismatch issue for electrical spin injection. We demonstrate electrical injection and detection of spin accumulation in Si above room temperature, and show that the corresponding spin lifetimes correlate with the Si carrier concentration, confirming that the spin accumulation measured occurs in the Si and not in interface trap states. An ideal tunnel barrier should exhibit several key material characteristics: a uniform and planar habit with well-controlled thickness, minimal defect / trapped charge density, a low resistance-area product for minimal power consumption, and compatibility with both the FM metal and semiconductor, insuring minimal diffusion to/from the surrounding materials at temperatures required for device processing. Graphene, offers all of the above, while preserving spin injection properties, making it a compelling solution to the conductivity mismatch for spin injection into Si. Although Graphene is very conductive in plane, it exhibits poor conductivity perpendicular to the plane. Its sp2 bonding results in a highly uniform, defect free layer, which is chemically inert, thermally robust, and essentially impervious to diffusion. The use of a single monolayer of graphene at the Si interface provides a much lower RA product than any film of an oxide thick enough to prevent pinholes (1 nm). Our results identify a new route to low resistance-area product spin-polarized contacts, a crucial requirement enabling future semiconductor spintronic devices, which rely upon two-terminal magnetoresistance, including spin-based transistors, logic and memory.

Stealth Biocompatible Si-Based Nanoparticles for Biomedical Applications

PubMed Central

Chaix, Arnaud; Gary-Bobo, Magali; Angeletti, Bernard; Masion, Armand; Da Silva, Afitz; Daurat, Morgane; Lichon, Laure; Garcia, Marcel; Morère, Alain; El Cheikh, Khaled; Durand, Jean-Olivier; Cunin, Frédérique; Auffan, Mélanie

2017-01-01

A challenge regarding the design of nanocarriers for drug delivery is to prevent their recognition by the immune system. To improve the blood residence time and prevent their capture by organs, nanoparticles can be designed with stealth properties using polymeric coating. In this study, we focused on the influence of surface modification with polyethylene glycol and/or mannose on the stealth behavior of porous silicon nanoparticles (pSiNP, ~200 nm). In vivo biodistribution of pSiNPs formulations were evaluated in mice 5 h after intravenous injection. Results indicated that the distribution in the organs was surface functionalization-dependent. Pristine pSiNPs and PEGylated pSiNPs were distributed mainly in the liver and spleen, while mannose-functionalized pSiNPs escaped capture by the spleen, and had higher blood retention. The most efficient stealth behavior was observed with PEGylated pSiNPs anchored with mannose that were the most excreted in urine at 5 h. The biodegradation kinetics evaluated in vitro were in agreement with these in vivo observations. The biocompatibility of the pristine and functionalized pSiNPs was confirmed in vitro on human cell lines and in vivo by cytotoxic and systemic inflammation investigations, respectively. With their biocompatibility, biodegradability, and stealth properties, the pSiNPs functionalized with mannose and PEG show promising potential for biomedical applications. PMID:28946628

Charge Transfer from Carbon Nanotubes to Silicon in Flexible Carbon Nanotube/Silicon Solar Cells.

PubMed

Li, Xiaokai; Mariano, Marina; McMillon-Brown, Lyndsey; Huang, Jing-Shun; Sfeir, Matthew Y; Reed, Mark A; Jung, Yeonwoong; Taylor, André D

2017-12-01

Mechanical fragility and insufficient light absorption are two major challenges for thin flexible crystalline Si-based solar cells. Flexible hybrid single-walled carbon nanotube (SWNT)/Si solar cells are demonstrated by applying scalable room-temperature processes for the fabrication of solar-cell components (e.g., preparation of SWNT thin films and SWNT/Si p-n junctions). The flexible SWNT/Si solar cells present an intrinsic efficiency ≈7.5% without any additional light-trapping structures. By using these solar cells as model systems, the charge transport mechanisms at the SWNT/Si interface are investigated using femtosecond transient absorption. Although primary photon absorption occurs in Si, transient absorption measurements show that SWNTs also generate and inject excited charge carriers to Si. Such effects can be tuned by controlling the thickness of the SWNTs. Findings from this study could open a new pathway for designing and improving the efficiency of photocarrier generation and absorption for high-performance ultrathin hybrid SWNT/Si solar cells. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Injection system used into SI engines for complete combustion and reduction of exhaust emissions in the case of alcohol and petrol alcohol mixtures feed

NASA Astrophysics Data System (ADS)

Ispas, N.; Cofaru, C.; Aleonte, M.

2017-10-01

Internal combustion engines still play a major role in today transportation but increasing the fuel efficiency and decreasing chemical emissions remain a great goal of the researchers. Direct injection and air assisted injection system can improve combustion and can reduce the concentration of the exhaust gas pollutes. Advanced air-to-fuel and combustion air-to-fuel injection system for mixtures, derivatives and alcohol gasoline blends represent a major asset in reducing pollutant emissions and controlling combustion processes in spark-ignition engines. The use of these biofuel and biofuel blending systems for gasoline results in better control of spark ignition engine processes, making combustion as complete as possible, as well as lower levels of concentrations of pollutants in exhaust gases. The main purpose of this paper was to provide most suitable tools for ensure the proven increase in the efficiency of spark ignition engines, making them more environmentally friendly. The conclusions of the paper allow to highlight the paths leading to a better use of alcohols (biofuels) in internal combustion engines of modern transport units.

MafA is a Key Molecule in Glucose and Energy Balance in the Central Nervous System and Peripheral Organs

PubMed Central

Tsuchiya, Mariko; Tsuchiya, Ken; Yasuda, Kazuki; Fujita, Mikiko; Takinishi, Akira; Furukawa, Maiko; Nitta, Kosaku; Maeda, Atsushi

2011-01-01

MafA is a strong transactivator of insulin in pancreatic β cells. Elucidating the profile of MafA action in organs other than the pancreas is essential. We established an mRNA interference technique that modifies the level of target mRNAs in mice in vivo. After rapidly injecting MafA-siRNA, the resulting changes in the gene profile were analyzed using a microarray system. Significant suppression of the MafA mRNA levels was observed in the pancreas, liver, adipose tissue, and brain of siRNA-injected mice. As we reported previously, the down-regulation of insulin mRNA and adipocytokines was observed in the pancreas, and MafA siRNA caused alterations in the expressions of genes related to lipid metabolism and cell growth in the liver, and the attenuation of cell differentiation in cultured adipocytes. In addition to the effects on these organs, MafA expression was immunohistochemically detected in the brain in our preliminary data, and the expression level in siRNA-treated mice was significantly suppressed. The expressions of the affected genes were distinct, including growth hormone, vasopressin, hypocretin, and pro-melanin-concentrating hormone, were almost completely down-regulated (to ~1/100). These results suggested that MafA is likely involved in the regulation of hormonal systems related to glucose metabolism, and MafA is likely positioned near the beginning of the cascade or may influence the expressions of the above-mentioned genes in coordination with other factors in brain tissue. Taken together, the findings in this study suggested that MafA functions as a transcription factor with distinct activities in each organ and is cross-linked in several organs. PMID:23675216

Functional outcome from sacroiliac joint prolotherapy in patients with sacroiliac joint instability.

PubMed

Hoffman, Martin D; Agnish, Vikram

2018-04-01

Examine the effectiveness of sacroiliac (SI) joint prolotherapy for SI joint instability, and characterize the patients most likely to benefit from this treatment. Retrospective cohort study. Department of Veterans Affairs outpatient physical medicine clinic. Patients referred for low back pain and diagnosed with SI joint instability received a series of three SI joint prolotherapy injections (15% dextrose in lidocaine) at approximately a one-month interval. The outcome of those completing treatment was retrospectively examined, and characteristics were compared between those with at least a minimum clinically important improvement and those without improvement. Patients completed the Oswestry Disability Index (ODI) before treatment was initiated, immediately preceding each prolotherapy injection, and at 3-4 month follow-up. Of 103 treated patients returning for post-treatment follow-up at a median of 117 days, 24 (23%) showed a minimum clinically important improvement despite a median of 2 years with low back pain and a mean (±SD) pre-intervention ODI of 54 ± 15 points. Much of the improvement was evident after the initial prolotherapy injection, and a 15-point improvement in ODI prior to the second prolotherapy injection had a sensitivity of 92% and specificity of 80% for determining which patients would improve. A satisfactory proportion of patients with symptomatic SI joint instability as an etiology of low back pain can have clinically meaningful functional gains with prolotherapy treatment. The patients who are not likely to improve with prolotherapy are generally evident by lack of improvement following the initial prolotherapy injection. Published by Elsevier Ltd.

Behavior of the Si/SiO2 interface observed by Fowler-Nordheim tunneling

NASA Technical Reports Server (NTRS)

Maserjian, J.; Zamani, N.

1982-01-01

Thin-oxide (40-50 A) metal oxide semiconductor (MOS) structures are shown to exhibit, before large levels of electron tunnel injection, the near-ideal behavior predicted for a uniform trapezoidal barrier with thick-oxide properties. The oscillatory field dependence caused by electron-wave interference at the Si/SiO2 interface suggests an abrupt, one-monolayer barrier transition (approximately 2.5 A) consistent with earlier work. After tunnel injection of 10 to the 17th - 5 x 10 to the 18th electrons/sq cm, the barrier undergoes appreciable degradation, leading to enhanced tunneling conductance. Reproducible behavior is observed among different samples. This effect is found to be consistent with the generation of positive states in the region of the oxide near the Si/SiO2 interface (less than 20 A), where the tunneling electrons emerge into the oxide conduction band.

Silicon chemistry in the mesosphere and lower thermosphere

PubMed Central

Gómez‐Martín, Juan Carlos; Feng, Wuhu; Janches, Diego

2016-01-01

Abstract Silicon is one of the most abundant elements in cosmic dust, and meteoric ablation injects a significant amount of Si into the atmosphere above 80 km. In this study, a new model for silicon chemistry in the mesosphere/lower thermosphere is described, based on recent laboratory kinetic studies of Si, SiO, SiO2, and Si+. Electronic structure calculations and statistical rate theory are used to show that the likely fate of SiO2 is a two‐step hydration to silicic acid (Si(OH)4), which then polymerizes with metal oxides and hydroxides to form meteoric smoke particles. This chemistry is then incorporated into a whole atmosphere chemistry‐climate model. The vertical profiles of Si+ and the Si+/Fe+ ratio are shown to be in good agreement with rocket‐borne mass spectrometric measurements between 90 and 110 km. Si+ has consistently been observed to be the major meteoric ion around 110 km; this implies that the relative injection rate of Si from meteoric ablation, compared to metals such as Fe and Mg, is significantly larger than expected based on their relative chondritic abundances. Finally, the global abundances of SiO and Si(OH)4 show clear evidence of the seasonal meteoric input function, which is much less pronounced in the case of other meteoric species. PMID:27668138

Sub-bandgap response of graphene/SiC Schottky emitter bipolar phototransistor examined by scanning photocurrent microscopy

NASA Astrophysics Data System (ADS)

Barker, Bobby G., Jr.; Chava, Venkata Surya N.; Daniels, Kevin M.; Chandrashekhar, M. V. S.; Greytak, Andrew B.

2018-01-01

Graphene layers grown epitaxially on SiC substrates are attractive for a variety of sensing and optoelectronic applications because the graphene acts as a transparent, conductive, and chemically responsive layer that is mated to a wide-bandgap semiconductor with large breakdown voltage. Recent advances in control of epitaxial growth and doping of SiC epilayers have increased the range of electronic device architectures that are accessible with this system. In particular, a recently-introduced Schottky-emitter bipolar phototransistor (SEPT) based on an epitaxial graphene (EG) emitter grown on a p-SiC base epilayer has been found to exhibit a maximum common emitter current gain of 113 and a UV responsivity of 7.1 A W-1. The behavior of this device, formed on an n +-SiC substrate that serves as the collector, was attributed to a very large minority carrier injection efficiency at the EG/p-SiC Schottky contact. This large minority carrier injection efficiency is in turn related to the large built-in potential found at a EG/p-SiC Schottky junction. The high performance of this device makes it critically important to analyze the sub bandgap visible response of the device, which provides information on impurity states and polytype inclusions in the crystal. Here, we employ scanning photocurrent microscopy (SPCM) with sub-bandgap light as well as a variety of other techniques to clearly demonstrate a localized response based on the graphene transparent electrode and an approximately 1000-fold difference in responsivity between 365 nm and 444 nm excitation. A stacking fault propagating from the substrate/epilayer interface, assigned as a single layer of the 8H-SiC polytype within the 4H-SiC matrix, is found to locally increase the photocurrent substantially. The discovery of this polytype heterojunction opens the potential for further development of heteropolytype devices based on the SEPT architecture.

Evidence of low injection efficiency for implanted p-emitters in bipolar 4H-SiC high-voltage diodes

NASA Astrophysics Data System (ADS)

Matthus, Christian D.; Huerner, Andreas; Erlbacher, Tobias; Bauer, Anton J.; Frey, Lothar

2018-06-01

In this study, the influence of the emitter efficiency on the forward current-voltage characteristics, especially the conductivity modulation of bipolar SiC-diodes was analyzed. It was determined that the emitter efficiency of p-emitters formed by ion implantation is significantly lower compared to p-emitters formed by epitaxy. In contrast to comparable studies, experimental approach was arranged that the influence of the quality of the drift-layer or the thickness of the emitter on the conductivity modulation could be excluded for the fabricated bipolar SiC-diodes of this work. Thus, it can be established that the lower emitter injection efficiency is mainly caused by the reduced electron lifetime in p-emitters formed by ion implantation. Therefore, a significant enhancement of the electron lifetime in implanted p-emitters is mandatory for e.g. SiC-MPS-diodes where the functionality of the devices depends significantly on the injection efficiency.

Development of antibody-siRNA conjugate targeted to cardiac and skeletal muscles.

PubMed

Sugo, Tsukasa; Terada, Michiko; Oikawa, Tatsuo; Miyata, Kenichi; Nishimura, Satoshi; Kenjo, Eriya; Ogasawara-Shimizu, Mari; Makita, Yukimasa; Imaichi, Sachiko; Murata, Shumpei; Otake, Kentaro; Kikuchi, Kuniko; Teratani, Mika; Masuda, Yasushi; Kamei, Takayuki; Takagahara, Shuichi; Ikeda, Shota; Ohtaki, Tetsuya; Matsumoto, Hirokazu

2016-09-10

Despite considerable efforts to develop efficient carriers, the major target organ of short-interfering RNAs (siRNAs) remains limited to the liver. Expanding the application outside the liver is required to increase the value of siRNAs. Here we report on a novel platform targeted to muscular organs by conjugation of siRNAs with anti-CD71 Fab' fragment. This conjugate showed durable gene-silencing in the heart and skeletal muscle for one month after intravenous administration in normal mice. In particular, 1μg siRNA conjugate showed significant gene-silencing in the gastrocnemius when injected intramuscularly. In a mouse model of peripheral artery disease, the treatment with myostatin-targeting siRNA conjugate by intramuscular injection resulted in significant silencing of myostatin and hypertrophy of the gastrocnemius, which was translated into the recovery of running performance. These data demonstrate the utility of antibody conjugation for siRNA delivery and the therapeutic potential for muscular diseases. Copyright © 2016 Elsevier B.V. All rights reserved.

Proton trapping in SiO 2 layers thermally grown on Si and SiC

NASA Astrophysics Data System (ADS)

Afanas'ev, V. V.; Ciobanu, F.; Pensl, G.; Stesmans, A.

2002-11-01

Positive charging of thermal SiO 2 layers on (1 0 0)Si and (0 0 0 1)6H-, 4H-SiC related to trapping of protons is studied using low-energy proton implantation into the oxide, and compared to the trapping of holes generated by 10-eV photons. Proton trapping has an initial probability close to 100% and shows little sensitivity to the annealing-induced oxygen deficiency of SiO 2. In contrast to protons, hole trapping in as-grown SiO 2 shows a much lower efficiency which increases upon oxide annealing, in qualitative correlation with the higher density of O 3Si• defects (E' centers) detected by electron spin resonance after hole injection. Despite these differences, the neutralization of positive charges induced by holes and protons has the same cross-section, and in both cases is accompanied by liberation of atomic H suggesting that protons account for positive charge in both cases. The rupture of Si-O bonds in the oxide observed upon proton injection suggests, as a first basic step, the bonding of a proton to a bridging oxygen atom in SiO 2 network.

Optimal Silicon Doping Layers of Quantum Barriers in the Growth Sequence Forming Soft Confinement Potential of Eight-Period In0.2Ga0.8N/GaN Quantum Wells of Blue LEDs.

PubMed

Wang, Hsiang-Chen; Chen, Meng-Chu; Lin, Yen-Sheng; Lu, Ming-Yen; Lin, Kuang-I; Cheng, Yung-Chen

2017-11-09

The features of eight-period In 0.2 Ga 0.8 N/GaN quantum wells (QWs) with silicon (Si) doping in the first two to five quantum barriers (QBs) in the growth sequence of blue light-emitting diodes (LEDs) are explored. Epilayers of QWs' structures are grown on 20 pairs of In 0.02 Ga 0.98 N/GaN superlattice acting as strain relief layers (SRLs) on patterned sapphire substrates (PSSs) by a low-pressure metal-organic chemical vapor deposition (LP-MOCVD) system. Temperature-dependent photoluminescence (PL) spectra, current versus voltage (I-V) curves, light output power versus injection current (L-I) curves, and images of high-resolution transmission electron microscopy (HRTEM) of epilayers are measured. The consequences show that QWs with four Si-doped QBs have larger carrier localization energy (41 meV), lower turn-on (3.27 V) and breakdown (- 6.77 V) voltages, and higher output power of light of blue LEDs at higher injection current than other samples. Low barrier height of QBs in a four-Si-doped QB sample results in soft confinement potential of QWs and lower turn-on and breakdown voltages of the diode. HRTEM images give the evidence that this sample has relatively diffusive interfaces of QWs. Uniform spread of carriers among eight QWs and superior localization of carriers in each well are responsible for the enhancement of light output power, in particular, for high injection current in the four-Si-doped QB sample. The results demonstrate that four QBs of eight In 0.2 Ga 0.8 N/GaN QWs with Si doping not only reduce the quantum-confined Stark effect (QCSE) but also improve the distribution and localization of carriers in QWs for better optical performance of blue LEDs.

Optimal Silicon Doping Layers of Quantum Barriers in the Growth Sequence Forming Soft Confinement Potential of Eight-Period In0.2Ga0.8N/GaN Quantum Wells of Blue LEDs

NASA Astrophysics Data System (ADS)

Wang, Hsiang-Chen; Chen, Meng-Chu; Lin, Yen-Sheng; Lu, Ming-Yen; Lin, Kuang-I.; Cheng, Yung-Chen

2017-11-01

The features of eight-period In0.2Ga0.8N/GaN quantum wells (QWs) with silicon (Si) doping in the first two to five quantum barriers (QBs) in the growth sequence of blue light-emitting diodes (LEDs) are explored. Epilayers of QWs' structures are grown on 20 pairs of In0.02Ga0.98N/GaN superlattice acting as strain relief layers (SRLs) on patterned sapphire substrates (PSSs) by a low-pressure metal-organic chemical vapor deposition (LP-MOCVD) system. Temperature-dependent photoluminescence (PL) spectra, current versus voltage ( I- V) curves, light output power versus injection current ( L- I) curves, and images of high-resolution transmission electron microscopy (HRTEM) of epilayers are measured. The consequences show that QWs with four Si-doped QBs have larger carrier localization energy (41 meV), lower turn-on (3.27 V) and breakdown (- 6.77 V) voltages, and higher output power of light of blue LEDs at higher injection current than other samples. Low barrier height of QBs in a four-Si-doped QB sample results in soft confinement potential of QWs and lower turn-on and breakdown voltages of the diode. HRTEM images give the evidence that this sample has relatively diffusive interfaces of QWs. Uniform spread of carriers among eight QWs and superior localization of carriers in each well are responsible for the enhancement of light output power, in particular, for high injection current in the four-Si-doped QB sample. The results demonstrate that four QBs of eight In0.2Ga0.8N/GaN QWs with Si doping not only reduce the quantum-confined Stark effect (QCSE) but also improve the distribution and localization of carriers in QWs for better optical performance of blue LEDs.

Silicon Chemistry in the Mesosphere and Lower Thermosphere

NASA Technical Reports Server (NTRS)

Plane, John M. C.; Gomez-Martin, Juan Carlos; Feng, Wuhu; Janches, Diego

2016-01-01

Silicon is one of the most abundant elements in cosmic dust, and meteoric ablation injects a significant amount of Si into the atmosphere above 80 km. In this study, a new model for silicon chemistry in the mesosphere lower thermosphere is described, based on recent laboratory kinetic studies of Si, SiO,SiO2, and S(exp +). Electronic structure calculations and statistical rate theory are used to show that the likely fate of SiO2 is a two-step hydration to silicic acid (Si(OH)4), which then polymerizes with metal oxides and hydroxides to form meteoric smoke particles. This chemistry is then incorporated into a whole atmosphere chemistry-climate model. The vertical profiles of Si+ and the Si(exp +)Fe(exp +) ratio are shown to be in good agreement with rocket-borne mass spectrometric measurements between 90 and 110 km. Si(exp +) has consistently been observed to be the major meteoric ion around 110 km; this implies that the relative injection rate of Si from meteoric ablation, compared to metals such as Fe and Mg, is significantly larger than expected based on the irrelative chondritic abundances. Finally, the global abundances of SiO and Si(OH)4 show clear evidence of the seasonal meteoric input function, which is much less pronounced in the case of other meteoric species.

Novel Shear-horizontal Surface Acoustic Wave Based Immunosensors Using SiO2Waveguiding Layers And Flow Injection Analysis.

PubMed

Guo, X S; Chen, Y Q; Yang, X L; Wang, L R

2005-01-01

Surface acoustic wave (SAW) devices based on shear-horizontal (SH) waves can be used as mass-sensitive immunosensors. This paper presents a novel SH-SAW sensor to detect anti-immunoglobulin (IgG) molecules by means of the antibody-antigen binding mechanism. The sensor system comprising dual delay lines was fabricated on 36° Y-X LiTaO3substrate. A SiO2layer was used as love mode waveguiding layers, well as insulating and chemically resistant protective layer. Moreover, flow injection analysis (FIA) method was used for continuous detection the protein molecules. The protein A was immobilized on the optional surface of the gold layer, then coupled with IgG to adsorb the antigens to be measured in the protein solution. The operational frequency of the system changed due to the interaction of antibody-antigen binding. The experimental result demonstrates the sensor has stable frequency response to the mass loading effect of the various anti-IgG concentrations with the sensitivity up to 3.3ng/ml/Hz.

Oxidative stress, inflammation, and DNA damage in multiple organs of mice acutely exposed to amorphous silica nanoparticles.

PubMed

Nemmar, Abderrahim; Yuvaraju, Priya; Beegam, Sumaya; Yasin, Javed; Kazzam, Elsadig E; Ali, Badreldin H

2016-01-01

The use of amorphous silica (SiO2) in biopharmaceutical and industrial fields can lead to human exposure by injection, skin penetration, ingestion, or inhalation. However, the in vivo acute toxicity of amorphous SiO2 nanoparticles (SiNPs) on multiple organs and the mechanisms underlying these effects are not well understood. Presently, we investigated the acute (24 hours) effects of intraperitoneally administered 50 nm SiNPs (0.25 mg/kg) on systemic toxicity, oxidative stress, inflammation, and DNA damage in the lung, heart, liver, kidney, and brain of mice. Lipid peroxidation was significantly increased by SiNPs in the lung, liver, kidney, and brain, but was not changed in the heart. Similarly, superoxide dismutase and catalase activities were significantly affected by SiNPs in all organs studied. While the concentration of tumor necrosis factor α was insignificantly increased in the liver and brain, its increase was statistically significant in the lung, heart, and kidney. SiNPs induced a significant elevation in pulmonary and renal interleukin 6 and interleukin-1 beta in the lung, liver, and brain. Moreover, SiNPs caused a significant increase in DNA damage, assessed by comet assay, in all the organs studied. SiNPs caused leukocytosis and increased the plasma activities of lactate dehydrogenase, creatine kinase, alanine aminotranferase, and aspartate aminotransferase. These results indicate that acute systemic exposure to SiNPs causes oxidative stress, inflammation, and DNA damage in several major organs, and highlight the need for thorough evaluation of SiNPs before they can be safely used in human beings.

Ocular silicon distribution and clearance following intravitreal injection of porous silicon microparticles.

PubMed

Nieto, Alejandra; Hou, Huiyuan; Sailor, Michael J; Freeman, William R; Cheng, Lingyun

2013-11-01

Porous silicon (pSi) microparticles have been investigated for intravitreal drug delivery and demonstrated good biocompatibility. With the appropriate surface chemistry, pSi can reside in vitreous for months or longer. However, ocular distribution and clearance pathway of its degradation product, silicic acid, are not well understood. In the current study, rabbit ocular tissue was collected at different time point following fresh pSi (day 1, 5, 9, 16, and 21) or oxidized pSi (day 3, 7, 14, 21, and 35) intravitreal injection. In addition, dual-probe simultaneous microdialysis of aqueous and vitreous humor was performed following a bolus intravitreal injection of 0.25 mL silicic acid (150 μg/mL) and six consecutive microdialysates were collected every 20 min. Silicon was quantified from the samples using inductively coupled plasma-optical emission spectroscopy. The study showed that following the intravitreal injection of oxidized pSi, free silicon was consistently higher in the aqueous than in the retina (8.1 ± 6.5 vs. 3.4 ± 3.9 μg/mL, p = 0.0031). The area under the concentration-time curve (AUC) of the retina was only about 24% that of the aqueous. The mean residence time was 16 days for aqueous, 13 days for vitreous, 6 days for retina, and 18 days for plasma. Similarly, following intravitreal fresh pSi, free silicon was also found higher in aqueous than in retina (7 ± 4.7 vs. 3.4 ± 4.1 μg/mL, p = 0.014). The AUC for the retina was about 50% of the AUC for the aqueous. The microdialysis revealed the terminal half-life of free silicon in the aqueous was 30 min and 92 min in the vitreous; the AUC for aqueous accounted for 38% of the AUC for vitreous. Our studies indicate that aqueous humor is a significant pathway for silicon egress from the eye following intravitreal injection of pSi crystals. Copyright © 2013 Elsevier Ltd. All rights reserved.

GaInAsP/InP lateral-current-injection distributed feedback laser with a-Si surface grating.

PubMed

Shindo, Takahiko; Okumura, Tadashi; Ito, Hitomi; Koguchi, Takayuki; Takahashi, Daisuke; Atsumi, Yuki; Kang, Joonhyun; Osabe, Ryo; Amemiya, Tomohiro; Nishiyama, Nobuhiko; Arai, Shigehisa

2011-01-31

We fabricated a novel lateral-current-injection-type distributed feedback (DFB) laser with amorphous-Si (a-Si) surface grating as a step to realize membrane lasers. This laser consists of a thin GaInAsP core layer grown on a semi-insulating InP substrate and a 30-nm-thick a-Si surface layer for DFB grating. Under a room-temperature continuous-wave condition, a low threshold current of 7.0 mA and high efficiency of 43% from the front facet were obtained for a 2.0-μm stripe width and 300-μm cavity length. A small-signal modulation bandwidth of 4.8 GHz was obtained at a bias current of 30 mA.

Reduction of plasma density in the Helicity Injected Torus with Steady Inductance experiment by using a helicon pre-ionization source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hossack, Aaron C.; Jarboe, Thomas R.; Victor, Brian S.

2013-10-15

A helicon based pre-ionization source has been developed and installed on the Helicity Injected Torus with Steady Inductance (HIT-SI) spheromak. The source initiates plasma breakdown by injecting impurity-free, unmagnetized plasma into the HIT-SI confinement volume. Typical helium spheromaks have electron density reduced from (2–3) × 10{sup 19} m{sup −3} to 1 × 10{sup 19} m{sup −3}. Deuterium spheromak formation is possible with density as low as 2 × 10{sup 18} m{sup −3}. The source also enables HIT-SI to be operated with only one helicity injector at injector frequencies above 14.5 kHz. A theory explaining the physical mechanism driving the reductionmore » of breakdown density is presented.« less

Spin accumulation in Si channels using CoFe/MgO/Si and CoFe/AlO{sub x}/Si tunnel contacts with high quality tunnel barriers prepared by radical-oxygen annealing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akushichi, T., E-mail: taiju.aku7@isl.titech.ac.jp; Shuto, Y.; Sugahara, S., E-mail: sugahara@isl.titech.ac.jp

We investigate spin injection into Si channels using three-terminal spin-accumulation (3T-SA) devices with high-quality CoFe/MgO/n-Si and CoFe/AlO{sub x}/n-Si tunnel spin-injectors whose tunnel barriers are formed by radical oxidation of Mg and Al thin films deposited on Si(100) substrates and successive annealing under radical-oxygen exposure. When the MgO and AlO{sub x} barriers are not treated by the radical-oxygen annealing, the Hanle-effect signals obtained from the 3T-SA devices are closely fitted by a single Lorentz function representing a signal due to trap spins. On the other hand, when the tunnel barriers are annealed under radical-oxygen exposure, the Hanle-effect signals can be accuratelymore » fitted by the superposition of a Lorentz function and a non-Lorentz function representing a signal due to accumulated spins in the Si channel. These results suggest that the quality improvement of tunnel barriers treated by radical-oxygen annealing is highly effective for spin-injection into Si channels.« less

A mechanism of charge transport in electroluminescent structures consisting of porous silicon and single-crystal silicon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Evtukh, A. A., E-mail: dept_5@isp.kiev.ua; Kaganovich, E. B.; Manoilov, E. G.

2006-02-15

Electroluminescent structures that emit in the visible region of the spectrum and are based on porous silicon (por-Si) formed on the p-Si substrate electrolytically using an internal current source are fabricated. The photoluminescent and electroluminescent properties, as well as the current-and capacitance-voltage characteristics of the structures are studied. Electroluminescence is observed only if the forward bias voltage is applied to the structure; the electroluminescence mechanism is based on the injection and is related to the radiative recombination of electrons and holes in quantum-dimensional Si nanocrystals. The injection of holes is controlled by the condition of their accumulation in the space-chargemore » region of p-Si and by a comparatively low concentration of electronic states at the por-Si/p-Si interface. The charge transport in por-Si is caused by the direct tunneling of charge carriers between the quantum-mechanical levels, which is ensured by an appreciable number of quantum-dimensional Si nanocrystals. The leakage currents are low as a result of a small variance in the sizes of Si nanocrystals and the absence of comparatively large nanocrystals.« less

A New Sacroiliac Joint Injection Technique and Its Short-Term Effect on Chronic Sacroiliac Region Pain.

PubMed

Do, Kyung Hee; Ahn, Sang Ho; Jones, Rodney; Jang, Sung Ho; Son, Su Min; Lee, Dong Gyu; Cho, Hee Kyung; Choi, Gyu Sik; Cho, Yun-Woo

2016-10-01

Sacroiliac joint (SIJ) injections have been used to provide short-term relief of SIJ pain. In this study, the authors investigated a new technique using a superior approach. Twenty four patients with chronic SI joint paint were recruited. Each patient was treated with a single SIJ intra-articular injection plus a periarticular injection of local anesthetic and corticosteroid in one procedure. Technical accuracy of the intra-articular procedure was determined by having 2 independent observers review and rate the quality of arthrograms obtained. Treatment effects were evaluated using a numerical rating scale, the Oswestry disability index (ODI) and global perceived effect (GPE). Both independent observers agreed that satisfactory arthrograms were obtained in all patients. Pain scores and disability were significantly reduced at 2 weeks and 4 weeks after treatment. Nineteen patients (79%) reported satisfaction with treatment. No serious adverse effects were encountered. The superior approach consistently achieves good access to the SI joint, and achieves outcomes that are compatible with those of other techniques. The superior approach constitutes an alternative to other techniques for injections into the SI joint. © 2016 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Peptide- and Amine-Modified Glucan Particles for the Delivery of Therapeutic siRNA

PubMed Central

Aouadi, Myriam; Vangala, Pranitha; Tencerova, Michaela; Amano, Shinya U.; Nicoloro, Sarah M.; Yawe, Joseph C.; Czech, Michael P.

2016-01-01

Translation of siRNA technology into the clinic is limited by the need for improved delivery systems that target specific cell types. Macrophages are particularly attractive targets for RNAi therapy because they promote pathogenic inflammatory responses in a number of important human diseases. We previously demonstrated that a multi-component formulation of β-1,3-D-glucan-encapsulated siRNA particles (GeRPs) can specifically and potently silence genes in mouse macrophages. A major advance would be to simplify the GeRP system by reducing the number of delivery components, thus enabling more facile manufacturing and future commercialization. Here we report the synthesis and evaluation of a simplified glucan-based particle (GP) capable of delivering siRNA in vivo to selectively silence macrophage genes. Covalent attachment of small-molecule amines and short peptides containing weak bases to GPs facilitated electrostatic interaction of the particles with siRNA and aided in the endosomal release of siRNA by the proton-sponge effect. Modified GPs were non-toxic and were efficiently internalized by macrophages in vitro. When injected intraperitoneally (i.p.), several of the new peptide-modified GPs were found to efficiently deliver siRNA to peritoneal macrophages in lean, healthy mice. In an animal model of obesity-induced inflammation, i.p. administration of one of the peptide-modified GPs (GP-EP14) bound to siRNA selectively reduced the expression of target inflammatory cytokines in the visceral adipose tissue macrophages. Decreasing adipose tissue inflammation resulted in an improvement of glucose metabolism in these metabolically challenged animals. Thus, modified GPs represent a promising new simplified system for the efficient delivery of therapeutic siRNAs specifically to phagocytic cells in vivo for modulation of inflammation responses. PMID:26815386

Antifibrotic effects of Smad4 small interfering RNAs in injured skeletal muscle after acute contusion.

PubMed

Li, H; Chen, J; Chen, S; Zhang, Q; Chen, S

2011-10-01

Muscle injuries are common musculoskeletal problems encountered in sports medicine clinics. In this study, we examined the effect of lentivirus-mediated small interfering RNA (siRNA) targeting Smad4 on the suppression of the fibrosis in injured skeletal muscles. We found that Smad4-siRNA could efficiently knock down the expression of Smad4 in the C2C12 myoblast cells and in the contunded mice gastrocnemius muscle. The expression of mRNA level of Smad4 decreased to 11% and 49% compared to the control group, respectively, and the expression of protein level decreased to 13% and 57% respectively. Moreover, the lentivirus-mediated siRNA was stably transfected only into the skeletal muscle and not into the liver of the animals. In contunded mice gastrocnemius, the collagenous and vimentin-positive area in the Smad4 siRNA group reduced to 36% and 37% compared to the control group, respectively. Furthermore, compared to the scrambled Smad4 siRNA-injected mice and PBS control-injected mice, the muscle function of the mice injected with lentivirus-mediated Smad4 siRNA improved in terms of both fast-twitch and tetanic strength (P<0.05). The results suggest that the gene therapy of inhibiting Smad4 by lentivirus-mediated siRNA could be a useful approach to prevent scar tissue formation and improve the function of injured skeletal muscle. © Georg Thieme Verlag KG Stuttgart · New York.

Silver nanoparticles-quercetin conjugation to siRNA against drug-resistant Bacillus subtilis for effective gene silencing: in vitro and in vivo.

PubMed

Sun, Dongdong; Zhang, Weiwei; Li, Nuan; Zhao, Zhiwei; Mou, Zhipeng; Yang, Endong; Wang, Weiyun

2016-06-01

Quercetin (Qe) exhibited extremely low water solubility, and thus, it was modified using silver nanoparticles (AgNPs). We fabricated AgNPs combined with Qe (AgNPs-Qe). The modification suggested that the synergistic properties of Qe enhanced the antibacterial activity of AgNPs. However, AgNPs-Qe exerted no effect on many kinds of drug-resistant bacteria, including Pseudomonas aeruginosa and Bacillus subtilis. RNA interference has considerable therapeutic potential because of its high specificity and potential capability to evade drug resistance. Therefore, we stabilized AgNPs-Qe with a layer of molecules (siRNA). The newly fabricated nanoparticles exerted improved effect on many kinds of bacteria, including the most prominent drug-resistant species B. subtilis. Agarose gel electrophoresis showed that the highest critical nitrogen-to-phosphorus (N/P) ratio occurred at a vector/siRNA with a w/w ratio of 7:1. Characterization experiment indicated that the diameter of siRNA/AgNPs-Qe was approximately 40 nm (40 ± 10 nm). Moreover, AgNPs-Qe were stabilized with a layer of siRNA that was approximately 10nm thick. Results of the in vitro study suggested that siRNA/AgNPs-Qe could destroy the cell wall and inhibit bacterial propagation. Meanwhile, the in vivo experiment on the animal bacteremia model, as well as the optical imaging of nude mice and their isolated organs, demonstrated that bacteria accumulated in the blood, heart, liver, spleen, lungs, and kidneys after the intravenous injection of B. subtilis. The bacteria in the blood and organs, as well as the inflamed cells in the tissues, gradually decreased after the mice received intravenous tail injection of siRNA/AgNPs-Qe for treatment. Both the in vitro and the in vivo studies exhibit that siRNA/AgNPs-Qe can be a potential nanoscale drug delivery system for B. subtilis targeting bacterimia. Copyright © 2016 Elsevier B.V. All rights reserved.

Robust spin-current injection in lateral spin valves with two-terminal Co2FeSi spin injectors

NASA Astrophysics Data System (ADS)

Oki, S.; Kurokawa, T.; Honda, S.; Yamada, S.; Kanashima, T.; Itoh, H.; Hamaya, K.

2017-05-01

We demonstrate generation and detection of pure spin currents by combining a two-terminal spin-injection technique and Co2FeSi (CFS) spin injectors in lateral spin valves (LSVs). We find that the two-terminal spin injection with CFS has the robust dependence of the nonlocal spin signals on the applied bias currents, markedly superior to the four-terminal spin injection with permalloy reported previously. In our LSVs, since the spin transfer torque from one CFS injector to another CFS one is large, the nonlocal magnetoresistance with respect to applied magnetic fields shows large asymmetry in high bias-current conditions. For utilizing multi-terminal spin injection with CFS as a method for magnetization reversals, the terminal arrangement of CFS spin injectors should be taken into account.

Local applications of myostatin-siRNA with atelocollagen increase skeletal muscle mass and recovery of muscle function.

PubMed

Kawakami, Emi; Kawai, Nobuhiko; Kinouchi, Nao; Mori, Hiroyo; Ohsawa, Yutaka; Ishimaru, Naozumi; Sunada, Yoshihide; Noji, Sumihare; Tanaka, Eiji

2013-01-01

Growing evidence suggests that small-interfering RNA (siRNA) can promote gene silencing in mammalian cells without induction of interferon synthesis or nonspecific gene suppression. Recently, a number of highly specific siRNAs targeted against disease-causing or disease-promoting genes have been developed. In this study, we evaluate the effectiveness of atelocollagen (ATCOL)-mediated application of siRNA targeting myostatin (Mst), a negative regulator of skeletal muscle growth, into skeletal muscles of muscular dystrophy model mice. We injected a nanoparticle complex containing myostatin-siRNA and ATCOL (Mst-siRNA/ATCOL) into the masseter muscles of mutant caveolin-3 transgenic (mCAV-3Tg) mice, an animal model for muscular dystrophy. Scrambled (scr) -siRNA/ATCOL complex was injected into the contralateral muscles as a control. Two weeks after injection, the masseter muscles were dissected for histometric analyses. To investigate changes in masseter muscle activity by local administration of Mst-siRNA/ATCOL complex, mouse masseter electromyography (EMG) was measured throughout the experimental period via telemetry. After local application of the Mst-siRNA/ATCOL complex, masseter muscles were enlarged, while no significant change was observed on the contralateral side. Histological analysis showed that myofibrils of masseter muscles treated with the Mst-siRNA/ATCOL complex were significantly larger than those of the control side. Real-time PCR analysis revealed a significant downregulation of Mst expression in the treated masseters of mCAV-3Tg mice. In addition, expression of myogenic transcription factors was upregulated in the Mst-siRNA-treated masseter muscle, while expression of adipogenic transcription factors was significantly downregulated. EMG results indicate that masseter muscle activity in mCAV-3Tg mice was increased by local administration of the Mst-siRNA/ATCOL complex. These data suggest local administration of Mst-siRNA/ATCOL complex could lead to skeletal muscle hypertrophy and recovery of motor disability in mCAV-3Tg mice. Therefore, ATCOL-mediated application of siRNA is a potential tool for therapeutic use in muscular atrophy diseases.

Intraindividual Analysis of Signal Intensity Changes in the Dentate Nucleus After Consecutive Serial Applications of Linear and Macrocyclic Gadolinium-Based Contrast Agents.

PubMed

Radbruch, Alexander; Weberling, Lukas D; Kieslich, Pascal J; Hepp, Johanna; Kickingereder, Philipp; Wick, Wolfgang; Schlemmer, Heinz-Peter; Bendszus, Martin

2016-11-01

Recent studies reported an increase in the dentate nucleus (DN)-to-pons signal intensity (SI) ratio (DN-pons SI ratio) on unenhanced T1-weighted images in patients who received consecutive serial injections of linear gadolinium-based contrast agents (GBCAs). In contrast, most studies found no increase in the DN-pons SI ratio when patients were treated with consecutive serial injections of macrocyclic GBCAs. However, the potential difference between macrocyclic and linear GBCAs has never been assessed in individuals who received subsequent applications of both contrast agents. In this retrospective study, we assessed the evolution of the DN-pons SI ratio change in patients that were treated with a comparable number of serial consecutive injections of the linear GBCA gadopentetate dimeglumine and subsequent serial injections of the macrocyclic GBCAs gadobutrol and gadoterate meglumine. Data of 36 patients was analyzed. All patients underwent at least 5 consecutive administrations of the linear GBCA gadopentetate dimeglumine followed by an equal number of consecutive administrations of the macrocyclic GBCA gadobutrol. In 12 of the 36 patients, 5 or more final consecutive injections of the macrocyclic GBCA gadoterate meglumine were analyzed additionally. The difference of DN-pons SI ratios on unenhanced T1-weighted images was calculated by subtracting the ratio at the first examination from the ratio at the last examination in each of the 3 periods. The mean DN-pons SI ratio difference in the gadopentetate dimeglumine period was significantly greater than 0 (mean ± SD, 0.0448 ± 0.0345; P < 0.001), whereas the mean DN-pons SI ratio difference in the subsequent gadobutrol and gadoterate meglumine period was significantly smaller than 0 (gadobutrol: -0.0178 ± 0.0459, P = 0.026; gadoterate meglumine: -0.0250 ± 0.0284, P = 0.011). In this observational study, the application of the linear GBCA gadopentetate dimeglumine was associated with a DN-pons SI ratio increase, whereas subsequent applications of the macrocyclic GBCAs gadobutrol or gadoterate meglumine in the same patients were not. Rather, the current data tentatively suggest a decrease in preexisting hyperintensities over time when linear GBCAs are changed to macrocyclic GBCAs, potentially indicating a washout effect or precipitation of gadolinium. Future patient studies need to include control groups to replicate the present results, and additional animal studies should be conducted to clarify the underlying mechanism of the proposed SI decrease.

Targeting NF-kB signaling with polymeric hybrid micelles that co-deliver siRNA and dexamethasone for arthritis therapy.

PubMed

Wang, Qin; Jiang, Hao; Li, Yan; Chen, Wenfei; Li, Hanmei; Peng, Ke; Zhang, Zhirong; Sun, Xun

2017-04-01

The transcription factor NF-kB plays a pivotal role in the pathogenesis of rheumatoid arthritis. Here we attempt to slow arthritis progression by co-delivering the glucocorticoid dexamethasone (Dex) and small-interfering RNA targeting NF-kB p65 using our previously developed polymeric hybrid micelle system. These micelles contain two similar amphiphilic copolymers: polycaprolactone-polyethylenimine (PCL-PEI) and polycaprolactone-polyethyleneglycol (PCL-PEG). The hybrid micelles loaded with Dex and siRNA effectively inhibited NF-kB signaling in murine macrophages more efficiently than micelles containing either Dex or siRNA on their own. In addition, the co-delivery system was able to switch macrophages from the M1 to M2 state. Injecting hybrid micelles containing Dex and siRNA into mice with collagen-induced arthritis led the therapeutic agents to accumulate in inflamed joints and reduce inflammation, without damaging renal or liver function. Thus, blocking NF-kB activation in inflammatory tissue using micelle-based co-delivery may provide a new approach for treating inflammatory disease. Copyright © 2017 Elsevier Ltd. All rights reserved.

Electrical spin injection from CoFe2O4 into p-Si semiconductor across MgO tunnel barrier for spin electronics

NASA Astrophysics Data System (ADS)

Panda, J.; Maji, Nilay; Nath, T. K.

2017-05-01

The room temperature spin injection and detection in non magnetic p-Si semiconductor have been studied in details in our CoFe2O4 (CFO)/MgO/p-Si heterojunction. The 3-terminal tunnel contacts have been made on the device for transport measurements. The electrical transport properties have been investigated at different isothermal conditions in the temperature range of 10-300 K. The spin accumulation in non magnetic p-Si semiconductor has been observed at different bias current under the applied magnetic field parallel to the film plane in the temperature range of 40-300 K. We have observed a giant spin accumulation in p-Si semiconductor using MgO/CFO tunnel contact. The Hanley effect is used to control the reduction of spin accumulation by applying magnetic field perpendicular to the carrier spin in the p-Si. The accumulated spin signal decays as a function of applied magnetic field for fixed bias current. These results will enable utilization of the spin degree of freedom in complementary Si devices and its further development.

Enhanced tunability of the composition in silicon oxynitride thin films by the reactive gas pulsing process

NASA Astrophysics Data System (ADS)

Aubry, Eric; Weber, Sylvain; Billard, Alain; Martin, Nicolas

2014-01-01

Silicon oxynitride thin films were sputter deposited by the reactive gas pulsing process. Pure silicon target was sputtered in Ar, N2 and O2 mixture atmosphere. Oxygen gas was periodically and solely introduced using exponential signals. In order to vary the injected O2 quantity in the deposition chamber during one pulse at constant injection time (TON), the tau mounting time τmou of the exponential signals was systematically changed for each deposition. Taking into account the real-time measurements of the discharge voltage and the I(O*)/I(Ar*) emission lines ratio, it is shown that the oscillations of the discharge voltage during the TON and TOFF times (injection of O2 stopped) are attributed to the preferential adsorption of the oxygen compared to that of the nitrogen. The sputtering mode alternates from a fully nitrided mode (TOFF time) to a mixed mode (nitrided and oxidized mode) during the TON time. For the highest injected O2 quantities, the mixed mode tends toward a fully oxidized mode due to an increase of the trapped oxygen on the target. The oxygen (nitrogen) concentration in the SiOxNy films similarly (inversely) varies as the oxygen is trapped. Moreover, measurements of the contamination speed of the Si target surface are connected to different behaviors of the process. At low injected O2 quantities, the nitrided mode predominates over the oxidized one during the TON time. It leads to the formation of Si3N4-yOy-like films. Inversely, the mixed mode takes place for high injected O2 quantities and the oxidized mode prevails against the nitrided one producing SiO2-xNx-like films.

Progress and Plans for the HIT--SI Experiment

NASA Astrophysics Data System (ADS)

Sieck, P. E.; Gu, P.; Hamp, W. T.; Izzo, V. A.; Jarboe, T. R.; Nelson, B. A.; O'Neill, R. G.; Redd, A. J.; Rogers, J. A.; Smith, R. J.

2002-11-01

The next step in the Helicity Injected Torus (HIT) program is HIT--SI, a ``bow tie'' spheromak to be formed and sustained by Steady Inductive Helicity Injection (SIHI). SIHI injects helicity at a nearly constant rate with no open field lines intersecting the boundary.(T. R. Jarboe, Fusion Technology 36) (1), p. 85, 1999 HIT--SI has been designed with a bow tie geometry to achieve stable high-β (>10%) spheromak equilibria.(U. Shumlak and T. R. Jarboe, Phys. Plasmas 7) (7), p. 2959, 2000 Injector dynamics depend greatly on reconnection rates in two locations: deep in the injector, and at the edge of the spheromak equilibrium. The first stage of HIT--SI operation concentrates on formation of a spheromak and sustainment for 1 ms, where the injector dynamics can be studied and the formation parameter space can be explored. Once these goals are met, the experiment will move into the second stage of operation, where the discharge duration will be extended and the device will inherit a suite of diagnostics from the existing HIT--II device.

In Vivo Biodistribution and Pharmacokinetics of Silica Nanoparticles as a Function of Geometry, Porosity and Surface Characteristics

PubMed Central

Yu, Tian; Hubbard, Dallin; Ray, Abhijit; Ghandehari, Hamidreza

2012-01-01

The in vivo biodistribution and pharmacokinetics of silica nanoparticles (SiO2) with systematically varied geometries, porosities, and surface characteristics were investigated in immune-competent CD-1 mice via the intravenous injection. The nanoparticles were taken up extensively by the liver and spleen. Mesoporous SiO2 exhibited higher accumulation in the lung than nonporous SiO2 of similar size. This accumulation was reduced by primary amine modification of the nanoparticles. High aspect ratio, amine-modified mesoporous nanorods showed enhanced lung accumulation compared to amine-modified mesoporous nanospheres. Accumulation of the nanoparticles was mainly caused by passive entrapment in the discontinuous openings in the endothelium of the liver and spleen or in the pulmonary capillaries, and was highly dependent on nanoparticle hydrodynamic size in circulation. The SiO2 were likely internalized by the reticulo-endothelial system (RES) following physical sequestration in the liver and spleen. The nanoparticles that were transiently associated with the lung were re-distributed out of this organ without significant internalization. Pharmacokinetic analysis showed that all SiO2 were rapidly cleared from systemic circulation. Amine-modified or nonporous nanoparticles possessed a higher volume of distribution at steady state than their pristine counterparts or mesoporous SiO2. In all, surface characteristics and porosity played important roles in influencing SiO2 biodistribution and pharmacokinetics. Increasing the aspect ratio of amine-modified mesoporous SiO2 from 1 to 8 resulted in increased accumulation in the lung. PMID:22684119

Effects of high optical injection levels in polycrystalline Si wafers on carrier transport

NASA Astrophysics Data System (ADS)

Steele, Doneisha; Semichaevsky, Andrey

High levels of carrier injection in polycrystalline Si may arise, for example, in solar cells under concentrated sunlight. Mechanisms for non-radiative carrier recombination include trap-mediated SRH and higher-order processes, e.g., Auger recombination. In this paper we present our experimental results for intensity-dependent carrier lifetimes and conduction currents in polycrystalline Si wafers illuminated with pulses of up to 50 Sun intensity. We also use a computational model for carrier transport that includes both SRH and Auger recombination mechanisms, in order to explain our experiments. The model allows quantifying recombination rate dependence on carrier concentration. Our goal is to relate the recombination rates to Si microstructure and defect densities that are revealed by IR PL images. We acknowledge the NSF support through Grant 1505377.

Low-Resistance Spin Injection into Silicon Using Graphene Tunnel Barriers

DTIC Science & Technology

2012-11-01

compromise spin injection/transport/detection. Ferromagnetic metals readily form silicides even at room tempera- ture19, and diffusion of the ferromagnetic... metal /tunnel barrier/Si contacts using 2 nm SiO2 (triangles), 1.5 nm Al2O3 (diamond) and monolayer graphene (circles) tunnel barriers prepared from...and B. T. Jonker* Spin manipulation in a semiconductor offers a new paradigm for device operation beyond Moore’s law. Ferromagnetic metals are ideal

Derivation of dynamo current drive in a closed-current volume and stable current sustainment in the HIT-SI experiment

NASA Astrophysics Data System (ADS)

Hossack, A. C.; Sutherland, D. A.; Jarboe, T. R.

2017-02-01

A derivation is given showing that the current inside a closed-current volume can be sustained against resistive dissipation by appropriately phased magnetic perturbations. Imposed-dynamo current drive theory is used to predict the toroidal current evolution in the helicity injected torus with steady inductive helicity injection (HIT-SI) experiment as a function of magnetic fluctuations at the edge. Analysis of magnetic fields from a HIT-SI discharge shows that the injector-imposed fluctuations are sufficient to sustain the measured toroidal current without instabilities whereas the small, plasma-generated magnetic fluctuations are not sufficiently large to sustain the current.

Microstructure and properties of FeSiCr/PA6 composites by injection molding using FeSiCr powders by phosphating and coupling treatment

NASA Astrophysics Data System (ADS)

Wang, Lulu; Qiao, Liang; Zheng, Jingwu; Cai, Wei; Ying, Yao; Li, Wangchang; Che, Shenglei; Yu, Jing

2018-04-01

FeSiCr/PA6 composites were prepared by injection molding using the FeSiCr powders modified by different phosphating agents and KH550 coupling agent. The resistivity, impact strength, magnetic permeability and magnetic loss of the FeSiCr/PA6 composites were measured. The morphologies of different FeSiCr powders and the FeSiCr/PA6 composites were also observed by scanning electron microscope (SEM). The results showed that 1-Hydroxyethylidene-1,1-diphosphonic acid, phytic acid and H3PO4 could improve the electrical resistivity of FeSiCr powders by forming the dense phosphating layer except diphenylphosphinic acid. However, the resistivity of FeSiCr/PA6 composites using the FeSiCr powders treated by all the four phosphating agents had no obvious increase though the phosphating layer on the surface of FeSiCr powder came into being. The nylon insulation layer had much stronger influence than the phosphating layer on electrical resistivity of the composites. After adding appropriate KH550 coupling agent, the impact strengths of FeSiCr/PA6 composites were significantly improved, which may be associated with the tiny gap between FeSiCr powder and PA6 matrix. The effects of the phosphating agents on the magnetic permeability and loss of the FeSiCr/PA6 were small and the mechanism were also discussed.

The Helicity Injected Torus (HIT) Program

NASA Astrophysics Data System (ADS)

Jarboe, T. R.; Gu, P.; Hamp, W.; Izzo, V.; Jewell, P.; Liptac, J.; McCollam, K. J.; Nelson, B. A.; Raman, R.; Redd, A. J.; Shumlak, U.; Sieck, P. E.; Smith, R. J.; Jain, K. K.; Nagata, M.; Uyama, T.

2000-10-01

The purpose of the Helicity Injected Torus (HIT) program is to develop current drive techniques for low-aspect-ratio toroidal plasmas. The present HIT-II spherical tokamak experiment is capable of both Coaxial Helicity Injection (CHI) and transformer action current drive. The HIT-II device itself is modestly sized (major radius R = 0.3 m, minor radius a = 0.2 m, with an on-axis magnetic field of up to Bo = 0.5 T), but has demonstrated toroidal plasma currents of up to 200 kA, using either CHI or transformer drive. An overview of ongoing research on HIT-II plasmas, including recent results, will be presented. An electron-locking model has been developed for helicity injection current drive; a description of this model will be presented, as well as comparisons to experimental results from the HIT and HIT-II devices. Empirical results from both the HIT program and past spheromak research, buttressed by theoretical developments, have led to the design of the upcoming HIT-SI (Helicity Injected Torus with Steady Inductive helicity injection) device (T.R. Jarboe, Fusion Technology 36, p. 85, 1999). HIT-SI will be able to form a high-beta spheromak, a low aspect ratio RFP or a spherical tokamak using constant inductive helicity injection. The HIT-SI design and construction progress will be presented.

Multivalent Presentation of MPL by Porous Silicon Microparticles Favors T Helper 1 Polarization Enhancing the Anti-Tumor Efficacy of Doxorubicin Nanoliposomes

PubMed Central

Liu, Xuewu; Yang, Marie; Williams, Laura; Savage, David J.; Gu, Jianhua; Rhudy, Jessica R.; Yokoi, Kenji; Lavelle, Ed C.; Serda, Rita E.

2014-01-01

Porous silicon (pSi) microparticles, in diverse sizes and shapes, can be functionalized to present pathogen-associated molecular patterns that activate dendritic cells. Intraperitoneal injection of MPL-adsorbed pSi microparticles, in contrast to free MPL, resulted in the induction of local inflammation, reflected in the recruitment of neutrophils, eosinophils and proinflammatory monocytes, and the depletion of resident macrophages and mast cells at the injection site. Injection of microparticle-bound MPL resulted in enhanced secretion of the T helper 1 associated cytokines IFN-γ and TNF-α by peritoneal exudate and lymph node cells in response to secondary stimuli while decreasing the anti-inflammatory cytokine IL-10. MPL-pSi microparticles independently exhibited anti-tumor effects and enhanced tumor suppression by low dose doxorubicin nanoliposomes. Intravascular injection of the MPL-bound microparticles increased serum IL-1β levels, which was blocked by the IL-1 receptor antagonist Anakinra. The microparticles also potentiated tumor infiltration by dendritic cells, cytotoxic T lymphocytes, and F4/80+ macrophages, however, a specific reduction was observed in CD204+ macrophages. PMID:24736547

Multivalent presentation of MPL by porous silicon microparticles favors T helper 1 polarization enhancing the anti-tumor efficacy of doxorubicin nanoliposomes.

PubMed

Meraz, Ismail M; Hearnden, Claire H; Liu, Xuewu; Yang, Marie; Williams, Laura; Savage, David J; Gu, Jianhua; Rhudy, Jessica R; Yokoi, Kenji; Lavelle, Ed C; Serda, Rita E

2014-01-01

Porous silicon (pSi) microparticles, in diverse sizes and shapes, can be functionalized to present pathogen-associated molecular patterns that activate dendritic cells. Intraperitoneal injection of MPL-adsorbed pSi microparticles, in contrast to free MPL, resulted in the induction of local inflammation, reflected in the recruitment of neutrophils, eosinophils and proinflammatory monocytes, and the depletion of resident macrophages and mast cells at the injection site. Injection of microparticle-bound MPL resulted in enhanced secretion of the T helper 1 associated cytokines IFN-γ and TNF-α by peritoneal exudate and lymph node cells in response to secondary stimuli while decreasing the anti-inflammatory cytokine IL-10. MPL-pSi microparticles independently exhibited anti-tumor effects and enhanced tumor suppression by low dose doxorubicin nanoliposomes. Intravascular injection of the MPL-bound microparticles increased serum IL-1β levels, which was blocked by the IL-1 receptor antagonist Anakinra. The microparticles also potentiated tumor infiltration by dendritic cells, cytotoxic T lymphocytes, and F4/80+ macrophages, however, a specific reduction was observed in CD204+ macrophages.

Deposition of thin Si and Ge films by ballistic hot electron reduction in a solution-dripping mode and its application to the growth of thin SiGe films

NASA Astrophysics Data System (ADS)

Suda, Ryutaro; Yagi, Mamiko; Kojima, Akira; Mentek, Romain; Mori, Nobuya; Shirakashi, Jun-ichi; Koshida, Nobuyoshi

2015-04-01

To enhance the usefulness of ballistic hot electron injection into solutions for depositing thin group-IV films, a dripping scheme is proposed. A very small amount of SiCl4 or GeCl4 solution was dripped onto the surface of a nanocrystalline Si (nc-Si) electron emitter, and then the emitter is driven without using any counter electrodes. It is shown that thin Si and Ge films are deposited onto the emitting surface. Spectroscopic surface and compositional analyses showed no extrinsic carbon contaminations in deposited thin films, in contrast to the results of a previous study using the dipping scheme. The availability of this technique for depositing thin SiGe films is also demonstrated using a mixture SiCl4+GeCl4 solution. Ballistic hot electrons injected into solutions with appropriate kinetic energies promote preferential reduction of target ions with no by-products leading to nuclei formation for the thin film growth. Specific advantageous features of this clean, room-temperature, and power-effective process is discussed in comparison with the conventional dry and wet processes.

Tumor-penetrating codelivery of siRNA and paclitaxel with ultrasound-responsive nanobubbles hetero-assembled from polymeric micelles and liposomes.

PubMed

Yin, Tinghui; Wang, Ping; Li, Jingguo; Wang, Yiru; Zheng, Bowen; Zheng, Rongqin; Cheng, Du; Shuai, Xintao

2014-07-01

Drug resistance is a big problem in systemic chemotherapy of hepatocellular carcinoma (HCC), and nanomedicines loaded with both chemotherapeutic agents (e.g. paclitaxel, PTX) and siRNA's targeting antiapoptosis genes (e.g. BCL-2) possess the advantages to simultaneously overcome the efflux pump-mediated drug resistance and antiapoptosis-related drug resistance. However, tumor-penetrating drug delivery with this type of nanomedicines is extremely difficult due to their relatively big size compared to the single drug-loaded nanomedicines. Aiming at address this problem, US-responsive nanobubbles encapsulating both anti-cancer drug paclitaxel (PTX) and siRNA (PTX-NBs/siRNA) for HCC treatment were developed by hetero-assembly of polymeric micelles and liposomes in the present study. Utilizing an external low-frequency US force imposed to the tumor site, effective tumor-penetrating codelivery of siRNA and PTX was achieved via tail vein injection of PTX-NBs/siRNA into nude mice bearing human HepG2 xerografts. Consequently, the PTX treatment-inducible antiapoptosis in HepG2 cells was effectively suppressed by the codelivered siRNA targeting an antiapoptosis gene (BCL-2 siRNA) during chemotherapy. Owing to the synergistic anti-cancer effect of two therapeutic agents, tumor growth was completely inhibited using low-dose PTX in animal study. Our results highlight the great potential of this type of US-responsive hetero-assemblies carrying both anti-cancer drug and siRNA as an effective nanomedicinal system for HCC therapy. Copyright © 2014 Elsevier Ltd. All rights reserved.

[Quantitative evaluation of Gd-EOB-DTPA uptake in phantom study for liver MRI].

PubMed

Hayashi, Norio; Miyati, Tosiaki; Koda, Wataru; Suzuki, Masayuki; Sanada, Shigeru; Ohno, Naoki; Hamaguchi, Takashi; Matsuura, Yukihiro; Kawahara, Kazuhiro; Yamamoto, Tomoyuki; Matsui, Osamu

2010-05-20

Gd-EOB-DTPA is a new liver specific MRI contrast media. In the hepatobiliary phase, contrast media is trapped in normal liver tissue, a normal liver shows high intensity, tumor/liver contrast becomes high, and diagnostic ability improves. In order to indicate the degree of uptake of the contrast media, the enhancement ratio (ER) is calculated. The ER is obtained by calculating (signal intensity (SI) after injection-SI before injection) / SI before injection. However, because there is no linearity between contrast media concentration and SI, ER is not correctly estimated by this method. We discuss a method of measuring ER based on SI and T(1) values using the phantom. We used a column phantom, with an internal diameter of 3 cm, that was filled with Gd-EOB-DTPA diluted solution. Moreover, measurement of the T(1) value by the IR method was also performed. The ER measuring method of this technique consists of the following three components: 1) Measurement of ER based on differences in 1/T(1) values using the variable flip angle (FA) method, 2) Measurement of differences in SI, and 3) Measurement of differences in 1/T(1) values using the IR method. ER values calculated by these three methods were compared. In measurement made using the variable FA method and the IR method, linearity was found between contrast media concentration and ER. On the other hand, linearity was not found between contrast media concentration and SI. For calculation of ER using Gd-EOB-DTPA, a more correct ER is obtained by measuring the T(1) value using the variable FA method.

Debinding and Sintering of an Injection-Moulded Hypereutectic Al⁻Si Alloy.

PubMed

Ni, Jiaqi; Yu, Muhuo; Han, Keqing

2018-05-16

Hypereutectic Al⁻Si (20 wt.%) alloy parts were fabricated by employing a powder injection moulding (PIM) technique with a developed multi-component binder system composed of high-density polyethylene (35 wt.%), carnauba wax (62 wt.%) and stearic acid (3 wt.%). The feedstocks contained 83 wt.% metal powders. The debinding process was carried out by a combination of solvent extraction and thermal decomposition. The effects of solvent debinding variables such as kind of solvents, debinding temperatures and time, and the bulk surface area to volume ratios on the debinding process were investigated. Thermal debinding and the subsequent sintering process were carried out in a heating sequence under a nitrogen atmosphere. The influences of sintering temperature and sintering time on the mechanical properties and structure were considered. Under the optimal sintering condition, sintering at 550 °C for 3 h, the final sintering parts were free of distortion and exhibited good mechanical properties. Relative sintered density, Brinell hardness, and tensile strength were ~95.5%, 58 HBW and ~154, respectively.

Plasma response to sustainment with imposed-dynamo current drive in HIT-SI and HIT-SI3

NASA Astrophysics Data System (ADS)

Hossack, A. C.; Jarboe, T. R.; Chandra, R. N.; Morgan, K. D.; Sutherland, D. A.; Penna, J. M.; Everson, C. J.; Nelson, B. A.

2017-07-01

The helicity injected torus—steady inductive (HIT-SI) program studies efficient, steady-state current drive for magnetic confinement plasmas using a novel experimental method. Stable, high-beta spheromaks have been sustained using steady, inductive current drive. Externally induced loop voltage and magnetic flux are oscillated together so that helicity and power injection are always positive, sustaining the edge plasma current indefinitely. Imposed-dynamo current drive (IDCD) theory further shows that the entire plasma current is sustained. The method is ideal for low aspect ratio, toroidal geometries with closed flux surfaces. Experimental studies of spheromak plasmas sustained with IDCD have shown stable magnetic profiles with evidence of pressure confinement. New measurements show coherent motion of a stable spheromak in response to the imposed perturbations. On the original device two helicity injectors were mounted on either side of the spheromak and the injected mode spectrum was predominantly n  =  1. Coherent, rigid motion indicates that the spheromak is stable and a lack of plasma-generated n  =  1 energy indicates that the maximum q is maintained below 1 during sustainment. Results from the HIT-SI3 device are also presented. Three inductive helicity injectors are mounted on one side of the spheromak flux conserver. Varying the relative injector phasing changes the injected mode spectrum which includes n  =  2, 3, and higher modes.

[Establishment of myocardial targeted nanoparticles and preliminary evaluation of its effects on prevention and treatment of myocardial injury].

PubMed

Liu, Y Y; Wang, C; Luo, P F; Xia, Z F

2017-11-20

Objective: To establish 3-{4-[2-hydroxyl-(1-methylethylamino) propoxy] phenyl} propionic acid cetylesters (PAC) modified nanoparticles, and preliminarily explore its cardiomyocyte-targeting function and protection effects on myocardium. Methods: (1) HL-1 myocardial cells were divided into cyanidin-3 (Cy3) marked non-targeted small interference RNA (Cy3-siNC) group and Cy3 marked small interference RNA designed for the nuclear factor kappa B (NF-κB)-p65 gene (Cy3-si435) group according to the random number table, with 3 wells in each group. Cells in Cy3-siNC group were transfected with Cy3-siNC, while cells in Cy3-si435 group were transfected with Cy3-si435. At transfection hour 24, the mRNA expression of NF-κB-p65 of cells was determined by real-time fluorescent quantitative polymerase chain reaction. (2) Multiple emulsificating solvent evaporating method was adopted to prepare PAC modified nanoparticles carried with Cy3-siNC (Cy3-siNC-PAC) and PAC modified nanoparticles carried with Cy3-si435 (Cy3-si435-PAC). The morphology of Cy3-si435-PAC nanoparticles was observed with scanning electron microscope, and the size and potential of Cy3-si435-PAC nanoparticles were detected by nanometer particle size and zeta potential analyzer. The entrapment efficiency and drug loadings of Cy3-si435-PAC nanoparticle were determined with ultraviolet spectrophotometer. The release of Cy3-si435 of Cy3-si435-PAC nanoparticles was determined by dialysis method. (3) Another batch of HL-1 cells were divided into 4 groups according to the random number table, with 9 wells in each group. Cells in negative control group were added with 5 μL phosphate buffer. Cells in 25, 50, and 100 mg/mL Cy3-si435-PAC nanoparticles groups were added with 5 μL 25, 50, and 100 mg/mL Cy3-si435-PAC nanoparticles, respectively. At transfection hour 6, 12, and 24, proliferation activity of cells in 3 wells of each group was detected by methyl thiazolyl tetrazolium method, respectively. (4) Another batch of HL-1 cells were cultured for 24 h, and then treated with 100 μL Cy3-si435-PAC nanoparticles. At transfection hour 0, 4, 8, 12, and 24, the percentage of cells uptaking Cy3-si435-PAC nanoparticles in 3 wells were detected by flow cytometry, respectively. (5) Another batch of HL-1 cells were divided into 2 groups according to the random number table, with 3 wells in each group. Cells in Cy3-siNC-PAC group were added with 100 μL Cy3-siNC-PAC nanoparticles, while cells in Cy3-si435-PAC group were added with 100 μL Cy3-si435-PAC nanoparticles. At transfection hour 24, the mRNA expression of NF-κB-p65 of cells was determined by real-time fluorescent quantitative polymerase chain reaction. (6) Six male C57BL/6J mice were divided into 2 groups according to the random number table, with 3 mice in each group. Mice in Cy3-siNC-lipopolysaccharide (LPS) group and Cy3-si435-LPS group were respectively injected with 500 μL Cy3-siNC-PAC nanoparticles and Cy3-si435-PAC nanoparticles (50 mg/mL) in the tail vein. At injection hour 24, mice in the two groups were intraperitoneally injected with 10 mg/kg LPS to induce myocardial injury. At post injury hour 24, the distribution of nanoparticles in mice was detected with small animal imager. (7) Another 9 male C57BL/6J mice were divided into 3 groups according to the random number table, with 3 mice in each group. Mice in Cy3-siNC-normal saline (NS) group and Cy3-siNC-LPS group were injected with 500 μL 50 mg/mL Cy3-siNC-PAC nanoparticles in the tail vein, while mice in Cy3-si435-LPS group were injected with 500 μL 50 mg/mL Cy3-si435-PAC nanoparticles. At injection hour 24, mice in Cy3-siNC-NS group were intraperitoneally injected with NS, while mice in Cy3-siNC-LPS group and Cy3-si435-LPS group were injected with 10 mg/kg LPS to induce myocardial injury. At post injury hour 24, pathological changes of myocardium of mice in each group were observed with HE staining. Data were processed with t test and one-way analysis of variance. Results: (1) The mRNA expression of NF-κB-p65 of cells in Cy3-si435 group was 0.183±0.004, significantly lower than 1.003±0.092 in Cy3-siNC group ( t =15.46, P <0.01). (2) The form of prepared Cy3-si435-PAC nanoparticles was good, with particle size of 146.0 nm, potential of -29.2 mV, entrapment efficiency of (86.9±1.1) %, drug loadings of (25.4±0.9) %, and stable Cy3-si435 release. (3) At transfection hour 6, 12, and 24, there were no statistically significant differences in proliferation activity of cells in the 4 groups (with F values from 0.129 to 2.512, P values above 0.05). (4) At transfection hour 0, 4, 8, 12, and 24, the percentages of cells uptaking Cy3-si435-PAC nanoparticles were (0.79±0.06)%, (31.04±1.59)%, (51.64±2.67)%, (68.15±2.60)%, and (83.68±4.67)%, respectively. (5) The mRNA expression of NF-κB-p65 of cells in Cy3-si435-PAC group was 0.286±0.015, significantly lower than 1.002±0.073 in Cy3-siNC-PAC group ( t =16.62, P <0.01). (6) At post injury hour 24, uniform distribution of nanoparticles could be observed in cardiomyocytes of mice in Cy3-siNC-LPS group and Cy3-si435-LPS group. (7) The structure of myocardial fibers of mice in Cy3-siNC-NS group was dense, with no inflammatory cells infiltration and uniform distribution of cytoplasm. The structure of myocardial fibers of mice in Cy3-siNC-LPS group were loose, with inflammatory cells infiltration and scattered distribution of cytoplasm. The structure of myocardial fibers of mice in Cy3-si435-LPS group was denser, with no obvious inflammatory cells infiltration and uniform distribution of cytoplasm. Conclusions: Cy3-si435-PAC nanoparticles have good morphology, uniform particle size, normal potential distribution, and no cell cytotoxicity. Cy3-si435-PAC nanoparticles can be effectively uptaked by HL-1 cells and suppress NF-κB-p65 mRNA expression. They also can effectively target to mice cardiomyocytes to reduce inflammatory cells infiltration and alleviate the myocardial injury of mice induced by LPS.

The Helicity Injected Torus Program

NASA Astrophysics Data System (ADS)

Jarboe, T. R.; Nelson, B. A.; Jewell, P. D.; Liptac, J. E.; McCollam, K. J.; Raman, R.; Redd, A. J.; Rogers, J. A.; Sieck, P. E.; Shumlak, U.; Smith, R. J.; Nagata, M.; Uyama, T.

1999-11-01

The Helicity Injected Torus--II (HIT--II) spherical torus is capable of both Coaxial Helicity Injection (CHI) and transformer action current drive. HIT--II has a major radius R = 0.3, minor radius a = 0.2, aspect ratio A = R/a = 1.5, with an on axis magnetic field of up to Bo = 0.67 T. HIT--II provides equilibrium control, CHI flux boundary conditions, and transformer action using 28 poloidal field coils, using active flux feedback control. HIT--II has driven up to 200 kA of plasma current, using either CHI or transformer drive. An overview and recent results of the HIT--II program will be presented. The development of a locked-electron current drive model for HIT and HIT--II has led to the design of a constant inductive helicity injection method for spherical torii. This method is incorporated in the design of the Helicity Injected Torus -- Steady Inductive (HIT-- SI)(T.R. Jarboe, Fusion Technology, 36) (1), p. 85, 1999 experiment. HIT--SI can form a high-beta spheromak, a low aspect ratio RFP, or a spherical tokamak in a steady-state manner without using electrodes. The HIT--SI design and methodology will be presented.

Engineering and Design of the Steady Inductive Helicity Injected Torus (HIT--SI)

NASA Astrophysics Data System (ADS)

Sieck, P. E.; Jarboe, T. R.; Nelson, B. A.; Rogers, J. A.; Shumlak, U.

1999-11-01

Steady Inductive Helicity Injection (SIHI) is an inductive helicity injection method that injects helicity at a nearly constant rate, without open field lines, and without removing any helicity or magnetic energy from the plasma.(T.R. Jarboe, Fusion Technology, 36) (1), p. 85, 1999 SIHI directly produces a rotating magnetic field structure, and in the frame of the rotating field the current profile is nearly time independent. The Steady Inductive Helicity Injected Torus (HIT--SI) is a spheromak designed to implement SIHI so that the current profile in the rotating frame is optimized. The geometry of HIT--SI will be presented, including the manufacturing techniques and metallurgical processes planned for construction of the close-fitting flux conserver. The flux conserver is made of aged chromium copper with 80% the conductivity of pure copper. The detailed electrical insulation requirements in the helicity injector design lead to a complex o-ring seal and a plasma-sprayed alumina insulation coating. This has prompted the construction of an o-ring prototype test fixture having the main features of the o-ring design and the alumina coating. The design and evaluation of this fixture will also be presented with vacuum and voltage test results.

Design of the Helicity Injected Torus with Steady Inductive Helicity Injection (HIT-SI)

NASA Astrophysics Data System (ADS)

Sieck, P. E.; Gu, P.; Hamp, W. T.; Izzo, V. A.; McCollam, K. J.; Jarboe, T. R.; Nelson, B. A.; Redd, A. J.; Rogers, J. A.; Shumlak, U.

2000-10-01

Steady Inductive Helicity Injection (SIHI) is an inductive current drive method that injects helicity at a nearly constant rate, without open field lines, and without removing any helicity or magnetic energy from the plasma(T.R. Jarboe, Fusion Technology 36), p. 85, 1999. SIHI directly produces a rotating magnetic field structure, and the current profile is nearly time independent in the frame of the rotating field. The Helicity Injected Torus with SIHI (HIT-SI) is a ``bow tie'' spheromak designed to implement SIHI so that the current profile in the rotating frame is optimized. SIHI is accomplished using two inductive helicity injectors that operate 90^o out of phase with each other. Each helicity injector is a 180^o segment of a ZT-P size (a ≈ 8cm, R ≈ 32cm) RFP. The presence of a spheromak equilibrium will be readily apparent on several diagnostics, including the surface magnetic probes. The design of HIT-SI is presented, including the manufacturing techniques and metallurgical processes being used in the construction of the one-meter diameter close-fitting flux conserver. Several small prototype tests have been performed to prove the vacuum seal and electrical insulation capabilities of the design, and a finite element stress analysis of the flux conserver will be presented.

Electrodeless Plasma Source: Phase II Update

NASA Astrophysics Data System (ADS)

Prager, James; Ziemba, Timothy; Miller, Kenneth

2012-10-01

Eagle Harbor Technologies, in collaboration with the University of Washington, has developed a low-impurity, electrode-less plasma source (EPS) for start-up and source plasma injection for fusion science applications. In order to not interfere with the experiment, a pre-ionizer/plasma source must meet a few critical criteria including low impurity production, low electromagnetic interference (EMI), and minimal disruption to the magnetic geometry of the experiment. This system was designed to be UHV compatible and bakable. Here we present the results of the EPS Phase II upgrade. The output plasma density was increased by two orders of magnitude to >10^17 m-3 in hydrogen with no magnetic field injected. EPS system integration with the HIT-SI experiment has begun.

The structure-property relationships of powder processed Fe-Al-Si alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prichard, Paul D.

1998-02-23

Iron-aluminum alloys have been extensively evaluated as semi-continuous product such as sheet and bar, but have not been evaluated by net shape P/M processing techniques such as metal injection molding. The alloy compositions of iron-aluminum alloys have been optimized for room temperature ductility, but have limited high temperature strength. Hot extruded powder alloys in the Fe-Al-Si system have developed impressive mechanical properties, but the effects of sintering on mechanical properties have not been explored. This investigation evaluated three powder processed Fe-Al-Si alloys: Fe-15Al, Fe-15Al-2.8Si, Fe-15Al-5Si (atomic %). The powder alloys were produced with a high pressure gas atomization (HPGA) processmore » to obtain a high fraction of metal injection molding (MIM) quality powder (D 84 < 32 μm). The powders were consolidated either by P/M hot extrusion or by vacuum sintering. The extruded materials were near full density with grain sizes ranging from 30 to 50 μm. The vacuum sintering conditions produced samples with density ranging from 87% to 99% of theoretical density, with an average grain size ranging from 26 μm to 104 μm. Mechanical property testing was conducted on both extruded and sintered material using a small punch test. Tensile tests were conducted on extruded bar for comparison with the punch test data. Punch tests were conducted from 25 to 550 C to determine the yield strength, and fracture energy for each alloy as a function of processing condition. The ductile to brittle transition temperature (DBTT) was observed to increase with an increasing silicon content. The Fe-15Al-2.8Si alloy was selected for more extensive testing due to the combination of high temperature strength and low temperature toughness due to the two phase α + DO 3 structure. This investigation provided a framework for understanding the effects of silicon in powder processing and mechanical property behavior of Fe-Al-Si alloys.« less

Osteogenesis and angiogenesis properties of dental pulp cell on novel injectable tricalcium phosphate cement by silica doped.

PubMed

Su, Ying-Fang; Lin, Chi-Chang; Huang, Tsui-Hsien; Chou, Ming-Yung; Yang, Jaw-Ji; Shie, Ming-You

2014-09-01

β-Tricalcium phosphate (β-TCP) is an osteoconductive material in clinical. In this study, we have doped silica (Si) into β-TCP and enhanced its bioactive and osteostimulative properties. To check its effectiveness, a series of Si-doped with different ratios were prepared to make new bioactive and biodegradable biocomposites for bone repair. Formation of the diametral tensile strength, ions released and weight loss of cements was considered after immersion. In addition, we also examined the behavior of human dental pulp cells (hDPCs) cultured on Si-doped β-TCP cements. The results showed that setting time and injectability of the Si-doped β-TCP cements were decreased as the Si content was increased. At the end of the immersion point, weight losses of 30.1%, 36.9%, 48.1%, and 55.3% were observed for the cement doping 0%, 10%, 20%, and 30% Si into β-TCP cements, respectively. In vitro cell experiments show that the Si-rich cements promote human dental pulp cell (hDPC) proliferation and differentiation. However, when the Si-doped in the cement is more than 20%, the amount of cells and osteogenesis protein of hDPCs was stimulated by Si released from Si-doped β-TCP cements. The degradation of β-TCP and osteogenesis of Si gives a strong reason to believe that these Si-doped β-TCP cements may prove to be promising bone repair materials. Copyright © 2014 Elsevier B.V. All rights reserved.

Development of Technologies on Innovative-Simplified Nuclear Power Plant using High-Efficiency Steam Injectors

NASA Astrophysics Data System (ADS)

Ohmori, Shuichi; Narabayashi, Tadashi; Mori, Michitsugu; Iwaki, Chikako; Asanuma, Yutaka; Goto, Shoji

A Steam Injector (SI) is a simple, compact and passive pump and also acts as a high-performance direct-contact heater. This provides SI with capability to serve also as a direct-contact feed-water heater that heats up feed-water by using extracted steam from turbine. Our technology development aims to significantly simplify equipment and reduce physical quantities by applying "High-Efficiency SI", which are applicable to a wide range of operation regimes beyond the performance and applicable range of existing SIs and enables unprecedented multistage and parallel operation, to the low-pressure feed-water heaters and Emergency Core Cooling System of nuclear power plants, as well as achieve high inherent safety to prevent severe accidents by keeping the core covered with water (a Severe Accident-Free Concept). This paper describes the results of the endurance and performance tests of low-pressure SIs for feed-water heaters with Jet-deaerator and core injection system.

Room-temperature continuous-wave electrically injected InGaN-based laser directly grown on Si

NASA Astrophysics Data System (ADS)

Sun, Yi; Zhou, Kun; Sun, Qian; Liu, Jianping; Feng, Meixin; Li, Zengcheng; Zhou, Yu; Zhang, Liqun; Li, Deyao; Zhang, Shuming; Ikeda, Masao; Liu, Sheng; Yang, Hui

2016-09-01

Silicon photonics would greatly benefit from efficient, visible on-chip light sources that are electrically driven at room temperature. To fully utilize the benefits of large-scale, low-cost manufacturing foundries, it is highly desirable to grow direct bandgap III-V semiconductor lasers directly on Si. Here, we report the demonstration of a blue-violet (413 nm) InGaN-based laser diode grown directly on Si that operates under continuous-wave current injection at room temperature, with a threshold current density of 4.7 kA cm-2. The heteroepitaxial growth of GaN on Si is confronted with a large mismatch in both the lattice constant and the coefficient of thermal expansion, often resulting in a high density of defects and even microcrack networks. By inserting an Al-composition step-graded AlN/AlGaN multilayer buffer between the Si and GaN, we have not only successfully eliminated crack formation, but also effectively reduced the dislocation density. The result is the realization of a blue-violet InGaN-based laser on Si.

Sustained Local Delivery of siRNA from an Injectable Scaffold

PubMed Central

Nelson, Christopher E.; Gupta, Mukesh K.; Adolph, Elizabeth J.; Shannon, Joshua M.; Guelcher, Scott A.; Duvall, Craig L.

2011-01-01

Controlled gene silencing technologies have significant, unrealized potential for use in tissue regeneration applications. The design described herein provides a means to package and protect siRNA within pH-responsive, endosomolytic micellar nanoparticles (si-NPs) that can be incorporated into nontoxic, biodegradable, and injectable polyurethane (PUR) tissue scaffolds. The si-NPs were homogeneously incorporated throughout the porous PUR scaffolds, and they were shown to be released via a diffusion-based mechanism for over three weeks. The siRNA-loaded micelles were larger but retained nano particulate morphology of approximately 100 nm diameter following incorporation into and release from the scaffolds. PUR scaffold releasate collected in vitro in PBS at 37°C for 1–4 days was able to achieve dose-dependent siRNA-mediated silencing with approximately 50% silencing achieved of the model gene GAPDH in NIH3T3 mouse fibroblasts. This promising platform technology provides both a research tool capable of probing the effects of local gene silencing and a potentially high-impact therapeutic approach for sustained, local silencing of deleterious genes within tissue defects. PMID:22061489

Bioactive hydrogel-nanosilica hybrid materials: a potential injectable scaffold for bone tissue engineering.

PubMed

Lewandowska-Łańcucka, Joanna; Fiejdasz, Sylwia; Rodzik, Łucja; Kozieł, Marcin; Nowakowska, Maria

2015-02-10

Novel bioactive organic-inorganic hybrid materials that can serve as injectable hydrogel systems for bone tissue regeneration were obtained. The silica nanoparticles (SiNP) prepared in situ by the Stöber method were dispersed in collagen, collagen-chitosan or chitosan sols, which were then subsequently crosslinked. Laser scanning confocal microscopy studies, in which fluorescent SiNP were applied, and SEM images indicated that the nanosilica particles were distributed in the whole volume of the hydrogel matrix. In vitro studies on fibroblast cell viability indicated that the hybrid materials are biocompatible. The silica nanoparticles dispersed in the biopolymer matrix had a positive effect on cell viability. Studies on the mineralization process under simulated body fluid (SBF) conditions confirmed the bioactivity of prepared materials. SEM images revealed mineral phase formation in the majority of the hybrid materials developed. EDS analysis indicated that these mineral phases are mainly composed of calcium and phosphorus. The XRD studies confirmed that mineral phases formed during SBF incubation of hybrid materials based on collagen are bone-like apatite minerals. The silica nanoparticles added to the hydrogel at the stage of synthesis induced the occurrence of mineralization. This process occurs not only at the surface of the material but in its entire volume, which is important for the preparation of scaffolds for bone tissue engineering. The ability of these materials to undergo in situ gelation under physiological temperature and their bioactivity as well as biocompatibility make them interesting candidates for bioactive injectable systems.

Electron-irradiated n+-Si as hole injection tunable anode of organic light-emitting diode

NASA Astrophysics Data System (ADS)

Li, Y. Z.; Wang, Z. L.; Wang, Y. Z.; Luo, H.; Xu, W. J.; Ran, G. Z.; Qin, G. G.

2013-01-01

Traditionally, n-type silicon is not regarded as a good anode of organic light emitting diode (OLED) due to the extremely low hole concentration in it; however, when doped with Au element which acts as carrier generation centers, it can be, as shown in our previous work. In this study, we demonstrate a new kind of carrier generation centers in n+-type silicon, which are the defects produced by 5 MeV electron irradiation. The density of carrier generation centers in the irradiated n+-Si anode can be controlled by tuning the electron irradiation time, and thus hole injection current in the OLEDs with the irradiated n+-Si anode can be optimized, leading to their much higher maximum efficiencies than those of the OLEDs with non-irradiated n+-Si anode. For a green phosphorescent OLED with the irradiated n+-Si anode, the current efficiency and power efficiency reach up to 12.1 cd/A and 4.2 lm/W, respectively.

A scanning transmission electron microscopy approach to analyzing large volumes of tissue to detect nanoparticles.

PubMed

Kempen, Paul J; Thakor, Avnesh S; Zavaleta, Cristina; Gambhir, Sanjiv S; Sinclair, Robert

2013-10-01

The use of nanoparticles for the diagnosis and treatment of cancer requires the complete characterization of their toxicity, including accurately locating them within biological tissues. Owing to their size, traditional light microscopy techniques are unable to resolve them. Transmission electron microscopy provides the necessary spatial resolution to image individual nanoparticles in tissue, but is severely limited by the very small analysis volume, usually on the order of tens of cubic microns. In this work, we developed a scanning transmission electron microscopy (STEM) approach to analyze large volumes of tissue for the presence of polyethylene glycol-coated Raman-active-silica-gold-nanoparticles (PEG-R-Si-Au-NPs). This approach utilizes the simultaneous bright and dark field imaging capabilities of STEM along with careful control of the image contrast settings to readily identify PEG-R-Si-Au-NPs in mouse liver tissue without the need for additional time-consuming analytical characterization. We utilized this technique to analyze 243,000 mm³ of mouse liver tissue for the presence of PEG-R-Si-Au-NPs. Nanoparticles injected into the mice intravenously via the tail vein accumulated in the liver, whereas those injected intrarectally did not, indicating that they remain in the colon and do not pass through the colon wall into the systemic circulation.

A Scanning Transmission Electron Microscopy (STEM) Approach to Analyzing Large Volumes of Tissue to Detect Nanoparticles

PubMed Central

Kempen, Paul J.; Thakor, Avnesh S.; Zavaleta, Cristina; Gambhir, Sanjiv S.; Sinclair, Robert

2013-01-01

The use of nanoparticles for the diagnosis and treatment of cancer requires the complete characterization of their toxicity, including accurately locating them within biological tissues. Owing to their size, traditional light microscopy techniques are unable to resolve them. Transmission electron microscopy provides the necessary spatial resolution to image individual nanoparticles in tissue but is severely limited by the very small analysis volume, usually on the order of tens of cubic microns. In this work we developed a scanning transmission electron microscopy (STEM) approach to analyze large volumes of tissue for the presence of polyethylene glycol coated Raman-active-silica-gold-nanoparticles (PEG-R-Si-Au-NPs). This approach utilizes the simultaneous bright and dark field imaging capabilities of STEM along with careful control of the image contrast settings to readily identify PEG-R-Si-Au-NPs in mouse liver tissue without the need for additional time consuming analytical characterization. We utilized this technique to analyze 243,000 µm3 of mouse liver tissue for the presence of PEG-R-Si-Au-NPs. Nanoparticles injected into the mice intravenously via the tail-vein accumulated in the liver while those injected intrarectally did not, indicating that they remain in the colon and do not pass through the colon wall into the systemic circulation. PMID:23803218

Surface Engineering of Porous Silicon Microparticles for Intravitreal Sustained Delivery of Rapamycin

PubMed Central

Nieto, Alejandra; Hou, Huiyuan; Moon, Sang Woong; Sailor, Michael J.; Freeman, William R.; Cheng, Lingyun

2015-01-01

Purpose. To understand the relationship between rapamycin loading/release and surface chemistries of porous silicon (pSi) to optimize pSi-based intravitreal delivery system. Methods. Three types of surface chemical modifications were studied: (1) pSi-COOH, containing 10-carbon aliphatic chains with terminal carboxyl groups grafted via hydrosilylation of undecylenic acid; (2) pSi-C12, containing 12-carbon aliphatic chains grafted via hydrosilylation of 1-dodecene; and (3) pSiO2-C8, prepared by mild oxidation of the pSi particles followed by grafting of 8-hydrocarbon chains to the resulting porous silica surface via a silanization. Results. The efficiency of rapamycin loading follows the order (micrograms of drug/milligrams of carrier): pSiO2-C8 (105 ± 18) > pSi-COOH (68 ± 8) > pSi-C12 (36 ± 6). Powder X-ray diffraction data showed that loaded rapamycin was amorphous and dynamic drug-release study showed that the availability of the free drug was increased by 6-fold (compared with crystalline rapamycin) by using pSiO2-C8 formulation (P = 0.0039). Of the three formulations in this study, pSiO2-C8-RAP showed optimal performance in terms of simultaneous release of the active drug and carrier degradation, and drug-loading capacity. Released rapamycin was confirmed with the fingerprints of the mass spectrometry and biologically functional as the control of commercial crystalline rapamycin. Single intravitreal injections of 2.9 ± 0.37 mg pSiO2-C8-RAP into rabbit eyes resulted in more than 8 weeks of residence in the vitreous while maintaining clear optical media and normal histology of the retina in comparison to the controls. Conclusions. Porous silicon–based rapamycin delivery system using the pSiO2-C8 formulation demonstrated good ocular compatibility and may provide sustained drug release for retina. PMID:25613937

Surface engineering of porous silicon microparticles for intravitreal sustained delivery of rapamycin.

PubMed

Nieto, Alejandra; Hou, Huiyuan; Moon, Sang Woong; Sailor, Michael J; Freeman, William R; Cheng, Lingyun

2015-01-22

To understand the relationship between rapamycin loading/release and surface chemistries of porous silicon (pSi) to optimize pSi-based intravitreal delivery system. Three types of surface chemical modifications were studied: (1) pSi-COOH, containing 10-carbon aliphatic chains with terminal carboxyl groups grafted via hydrosilylation of undecylenic acid; (2) pSi-C12, containing 12-carbon aliphatic chains grafted via hydrosilylation of 1-dodecene; and (3) pSiO2-C8, prepared by mild oxidation of the pSi particles followed by grafting of 8-hydrocarbon chains to the resulting porous silica surface via a silanization. The efficiency of rapamycin loading follows the order (micrograms of drug/milligrams of carrier): pSiO2-C8 (105 ± 18) > pSi-COOH (68 ± 8) > pSi-C12 (36 ± 6). Powder X-ray diffraction data showed that loaded rapamycin was amorphous and dynamic drug-release study showed that the availability of the free drug was increased by 6-fold (compared with crystalline rapamycin) by using pSiO2-C8 formulation (P = 0.0039). Of the three formulations in this study, pSiO2-C8-RAP showed optimal performance in terms of simultaneous release of the active drug and carrier degradation, and drug-loading capacity. Released rapamycin was confirmed with the fingerprints of the mass spectrometry and biologically functional as the control of commercial crystalline rapamycin. Single intravitreal injections of 2.9 ± 0.37 mg pSiO2-C8-RAP into rabbit eyes resulted in more than 8 weeks of residence in the vitreous while maintaining clear optical media and normal histology of the retina in comparison to the controls. Porous silicon-based rapamycin delivery system using the pSiO2-C8 formulation demonstrated good ocular compatibility and may provide sustained drug release for retina. Copyright 2015 The Association for Research in Vision and Ophthalmology, Inc.

Isotropic plasma etching of Ge Si and SiN x films

DOE PAGES

Henry, Michael David; Douglas, Erica Ann

2016-08-31

This study reports on selective isotropic dry etching of chemically vapor deposited (CVD) Ge thin film, release layers using a Shibaura chemical downstream etcher (CDE) with NF 3 and Ar based plasma chemistry. Relative etch rates between Ge, Si and SiN x are described with etch rate reductions achieved by adjusting plasma chemistry with O 2. Formation of oxides reducing etch rates were measured for both Ge and Si, but nitrides or oxy-nitrides created using direct injection of NO into the process chamber were measured to increase Si and SiN x etch rates while retarding Ge etching.

Functional analysis of two polygalacturonase genes in Apolygus lucorum associated with eliciting plant injury using RNA interference.

PubMed

Zhang, Wanna; Liu, Bing; Lu, Yanhui; Liang, Gemei

2017-04-01

Salivary enzymes of many piercing-sucking insects lead to host plant injury. The salivary enzymes, polygalacturonase (PGs), act in insect feeding. PG family genes have been cloned from the mirid bug Apolygus lucorum, a pest of cotton and other host crops in China. We investigated the function of two PG genes that are highly expressed in A. lucorum nymphs (PG3-4) and adults (PG3-5), using siRNA injection-based RNA interference (RNAi). Accumulation of mRNA encoding both genes and their cognate proteins was significantly reduced (>60%) in experimental compared control green fluorescent protein (GFP) siRNA-treated mirids at 48 h post injection. Injury levels of cotton buds were also significantly reduced after injecting saliva isolated from PG3-4 and PG3-5 siRNA-treated A. lucorum. These results demonstrate that these two PG act in A. lucorum elicitation of plant injury. © 2017 Wiley Periodicals, Inc.

Nanoscale charge transfer and diffusion at the MoS2/SiO2 interface by atomic force microscopy: contact injection versus triboelectrification.

PubMed

Xu, Rui; Ye, Shili; Xu, Kunqi; Lei, Le; Hussain, Sabir; Zheng, Zhiyue; Pang, Fei; Xing, Shuya; Liu, Xinmeng; Ji, Wei; Cheng, Zhihai

2018-08-31

Understanding the process of charge generation, transfer, and diffusion between two-dimensional (2D) materials and their supporting substrates is very important for potential applications of 2D materials. Compared with the systematic studies of triboelectric charging in a bulk sample, a fundamental understanding of the triboelectrification of the 2D material/insulator system is rather limited. Here, the charge transfer and diffusion of both the SiO 2 surface and MoS 2 /SiO 2 interface through contact electrification and frictional electrification are investigated systematically in situ by scanning Kelvin probe microscopy and dual-harmonic electrostatic force microscopy. Different from the simple static charge transfer between SiO 2 and the PtSi alloy atomic force microscope (AFM) tip, the charge transfer between the tip and the MoS 2 /SiO 2 system is complicated. Triboelectric charges, generated by contact or frictional electrification with the AFM tip, are trapped at the MoS 2 /SiO 2 interface and act as floating gates. The local charge discharge processes can be obtained by monitoring the surface potential. The charge decay time (τ) of the MoS 2 /SiO 2 interface is one (or two) orders of magnitude larger than the decay time τ of the SiO 2 surface. This work facilitates an understanding of the triboelectric and de-electrification of the interface between 2D materials and substrates. In addition to the charge transfer and diffusion, we demonstrate the nanopatterns of surface and interfacial charges, which have great potential for the application of self-assembly of charged nanostructures.

Advanced Ceramics from Preceramic Polymers Modified at the Nano-Scale: A Review.

PubMed

Bernardo, Enrico; Fiocco, Laura; Parcianello, Giulio; Storti, Enrico; Colombo, Paolo

2014-03-06

Preceramic polymers, i.e. , polymers that are converted into ceramics upon heat treatment, have been successfully used for almost 40 years to give advanced ceramics, especially belonging to the ternary SiCO and SiCN systems or to the quaternary SiBCN system. One of their main advantages is the possibility of combining the shaping and synthesis of ceramics: components can be shaped at the precursor stage by conventional plastic-forming techniques, such as spinning, blowing, injection molding, warm pressing and resin transfer molding, and then converted into ceramics by treatments typically above 800 °C. The extension of the approach to a wider range of ceramic compositions and applications, both structural and thermo-structural (refractory components, thermal barrier coatings) or functional (bioactive ceramics, luminescent materials), mainly relies on modifications of the polymers at the nano-scale, i.e. , on the introduction of nano-sized fillers and/or chemical additives, leading to nano-structured ceramic components upon thermal conversion. Fillers and additives may react with the main ceramic residue of the polymer, leading to ceramics of significant engineering interest (such as silicates and SiAlONs), or cause the formation of secondary phases, significantly affecting the functionalities of the polymer-derived matrix.

Synthesis of ultrafine Si3N4 powder in RF-RF plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sato, Michitaka; Nishio, Hiroaki

1991-10-01

A newly designed plasma-CVD apparatus mounted with the RF-RF type plasma torch was introduced to synthesize ultrafine powders of silicon nitride (Si3N4). The RF-RF plasma system (the combination of a main (lower) and controlling (upper) RF plasma) improved the stability of simple RF plasma and solved the impurity problem of dc-RF hybrid plasma. The reaction of SiCl4 and NH3, which were radially injected into the tail flames of the upper and lower plasmas, respectively, yielded near-stoichiometric amorphous powders of Si3N4. The nitrogen content in the products largely depended on the flow rate of the quenching gas, a mixture of NH3more » (reactant) and H2. The oxygen content and metal impurities are 2-3 wt pct and less than 200 ppm, respectively. The powder particles had an average diameter of about 15 nm with a narrow size distribution, and showed extreme air sensitivity. Conspicuous crystallazation and particle growth occurred when heated at temperatures above 1400 C. These results suggested that the RF-RF system was a potential reactor for the synthesis of ultrafine powders with excellent sinterability at relatively low temperatures. 9 refs.« less

Optical Diagnostics on HIT-SI3

NASA Astrophysics Data System (ADS)

Everson, Christopher; Jarboe, Thomas; Morgan, Kyle

2016-10-01

Interferometry and Thomson Scattering are implemented on the HIT-SI3 (Helicity Injected Torus - Steady Inductive 3) device to provide time resolved measurements of electron density and spatially resolved measurements of electron temperature, respectively. HIT-SI3 is a modification of the original HIT-SI apparatus that uses three injectors instead of two. The scientific aim of HIT-SI3 is to develop a deeper understanding of how injector behavior and interactions influence current drive and spheromak stability. The interferometer system makes use of an intermediate frequency between two parallel 184.3 μm Far-Infrared (FIR) laser cavities which are optically pumped by a CO2 laser. The phase shift in this beat frequency due to the plasma index of refraction is used to calculate the line-integrated electron density. To measure the electron temperature, Thomson Scattered light from a 20 J (1 GW pulse) Ruby laser off of free electrons in the HIT-SI3 plasma is measured simultaneously at four locations across the spheromak (nominally 23 cm minor radius). Polychromators bin the collected light into 3 spectral bands to detect the relative level of scattering. Work supported by the D.O.E.

Eutectic Nano-Droplet Template Injection into Bulk Silicon to Construct Porous Frameworks with Concomitant Conformal Coating as Anodes for Li-Ion Batteries

PubMed Central

Qu, Fei; Li, Chilin; Wang, Zumin; Wen, Yuren; Richter, Gunther; Strunk, Horst P.

2015-01-01

Building porosity in monolithic materials is highly desired to design 3D electrodes, however ex-situ introduction or in-situ generation of nano-scale sacrificial template is still a great challenge. Here Al-Si eutectic droplet templates are uniformly injected into bulk Si through Al-induced solid-solid convection to construct a highly porous Si framework. This process is concomitant with process-inherent conformal coating of ion-conductive oxide. Such an all-in-one method has generated a (continuously processed) high-capacity Si anode integrating longevity and stable electrolyte-anode diaphragm for Li-ion batteries (e.g. a reversible capacity as large as ~1800 mAh/g or ~350 μAh/cm2-μm with a CE of ~99% at 0.1 C after long-term 400 cycles). PMID:25988370

Eutectic nano-droplet template injection into bulk silicon to construct porous frameworks with concomitant conformal coating as anodes for Li-ion batteries.

PubMed

Qu, Fei; Li, Chilin; Wang, Zumin; Wen, Yuren; Richter, Gunther; Strunk, Horst P

2015-05-19

Building porosity in monolithic materials is highly desired to design 3D electrodes, however ex-situ introduction or in-situ generation of nano-scale sacrificial template is still a great challenge. Here Al-Si eutectic droplet templates are uniformly injected into bulk Si through Al-induced solid-solid convection to construct a highly porous Si framework. This process is concomitant with process-inherent conformal coating of ion-conductive oxide. Such an all-in-one method has generated a (continuously processed) high-capacity Si anode integrating longevity and stable electrolyte-anode diaphragm for Li-ion batteries (e.g. a reversible capacity as large as ~1800 mAh/g or ~350 μAh/cm(2)-μm with a CE of ~99% at 0.1 C after long-term 400 cycles).

Profiling of the injected charge drift current transients by cross-sectional scanning technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaubas, E., E-mail: eugenijus.gaubas@ff.vu.lt; Ceponis, T.; Pavlov, J.

2014-02-07

The electric field distribution and charge drift currents in Si particle detectors are analyzed. Profiling of the injected charge drift current transients has been implemented by varying charge injection position within a cross-sectional boundary of the particle detector. The obtained profiles of the induction current density and duration of the injected charge drift pulses fit well the simulated current variations. Induction current transients have been interpreted by different stages of the bipolar and monopolar drift of the injected carriers. Profiles of the injected charge current transients registered in the non-irradiated and neutron irradiated Si diodes are compared. It has beenmore » shown that the mixed regime of the competing processes of drift, recombination, and diffusion appears in the measured current profiles on the irradiated samples. The impact of the avalanche effects can be ignored based on the investigations presented. It has been shown that even a simplified dynamic model enabled us to reproduce the main features of the profiled transients of induced charge drift current.« less

Nanoengineered multimodal contrast agent for medical image guidance

NASA Astrophysics Data System (ADS)

Perkins, Gregory J.; Zheng, Jinzi; Brock, Kristy; Allen, Christine; Jaffray, David A.

2005-04-01

Multimodality imaging has gained momentum in radiation therapy planning and image-guided treatment delivery. Specifically, computed tomography (CT) and magnetic resonance (MR) imaging are two complementary imaging modalities often utilized in radiation therapy for visualization of anatomical structures for tumour delineation and accurate registration of image data sets for volumetric dose calculation. The development of a multimodal contrast agent for CT and MR with prolonged in vivo residence time would provide long-lasting spatial and temporal correspondence of the anatomical features of interest, and therefore facilitate multimodal image registration, treatment planning and delivery. The multimodal contrast agent investigated consists of nano-sized stealth liposomes encapsulating conventional iodine and gadolinium-based contrast agents. The average loading achieved was 33.5 +/- 7.1 mg/mL of iodine for iohexol and 9.8 +/- 2.0 mg/mL of gadolinium for gadoteridol. The average liposome diameter was 46.2 +/- 13.5 nm. The system was found to be stable in physiological buffer over a 15-day period, releasing 11.9 +/- 1.1% and 11.2 +/- 0.9% of the total amounts of iohexol and gadoteridol loaded, respectively. 200 minutes following in vivo administration, the contrast agent maintained a relative contrast enhancement of 81.4 +/- 13.05 differential Hounsfield units (ΔHU) in CT (40% decrease from the peak signal value achieved 3 minutes post-injection) and 731.9 +/- 144.2 differential signal intensity (ΔSI) in MR (46% decrease from the peak signal value achieved 3 minutes post-injection) in the blood (aorta), a relative contrast enhancement of 38.0 +/- 5.1 ΔHU (42% decrease from the peak signal value achieved 3 minutes post-injection) and 178.6 +/- 41.4 ΔSI (62% decrease from the peak signal value achieved 3 minutes post-injection) in the liver (parenchyma), a relative contrast enhancement of 9.1 +/- 1.7 ΔHU (94% decrease from the peak signal value achieved 3 minutes post-injection) and 461.7 +/- 78.1 ΔSI (60% decrease from the peak signal value achieved 5 minutes post-injection) in the kidney (cortex) of a New Zealand white rabbit. This multimodal contrast agent, with prolonged in vivo residence time and imaging efficacy, has the potential to bring about improvements in the fields of medical imaging and radiation therapy, particularly for image registration and guidance.

NIMROD Simulations of the HIT-SI and HIT-SI3 Devices

NASA Astrophysics Data System (ADS)

Morgan, Kyle; Jarboe, Tom; Hossack, Aaron; Chandra, Rian; Everson, Chris

2017-10-01

The Helicity Injected Torus with Steady Inductive helicity injection (HIT-SI) experiment uses a set of inductively driven helicity injectors to apply non-axisymmetric current drive on the edge of the plasma, driving an axisymmetric spheromak equilibrium in a central confinement volume. Significant improvements have been made to extended MHD modeling of HIT-SI, with both the resolution of disagreement at high injector frequencies in HIT-SI in addition to successes with the new upgraded HIT-SI3 device. Previous numerical studies of HIT-SI, using a zero-beta eMHD model, focused on operations with a drive frequency of 14.5 kHz, and found reduced agreement with both the magnetic profile and current amplification at higher frequencies (30-70 kHz). HIT-SI3 has three helicity injectors which are able to operate with different mode structures of perturbations through the different relative temporal phasing of the injectors. Simulations that allow for pressure gradients have been performed in the parameter regimes of both devices using the NIMROD code and show improved agreement with experimental results, most notably capturing the observed Shafranov-shift due to increased beta observed at higher finj in HIT-SI and the variety of toroidal perturbation spectra available in HIT-SI3. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences under Award Number DE-FG02- 96ER54361.

Method for Impeding Degradation of Porous Silicon Structures

NASA Technical Reports Server (NTRS)

Vilentchouk, Biana Godin; Ferrari, Mauro

2011-01-01

This invention relates to surface modification of porosified silicon (pSi) structures with poly(alkylene) glycols for the purpose of controlled degradation of the silicon matrix and tailored release of encapsulated substances for biomedical applications. The pSi structures are currently used in diverse biomedical applications including bio-molecular screening, optical bio-sensoring, and drug delivery by means of injectable/orally administered carriers and implantable devices. The size of the pores and the surface chemistry of the pSi structure can be controlled during the microfabrication process and thereafter. A fine regulation of the degradation kinetics of mesoporous silicon structures is of fundamental importance. Polyethylene glycols (PEGs) represent the major category of surface modifying agents used in classical drug delivery systems and in pharmaceutical dosage forms. PEGylation enables avoidance of RES uptake, thus prolonging circulation time of intravenously injectable nanovectors. PEG molecules demonstrate little toxicity and immunogenicity, and are cleared from the body through the urine (molecular weight, MW less than 30 kDa) or in the feces (MW greater than 30kDa). The invention focuses on the possibility of finely tuning the degradation kinetics of the pSi nanovectors and other structures through surface conjugation of PEGs with various backbone lengths/MWs. To prove the concept, pSi nanovectors were covalently conjugated to seven PEGs with MW from 245 to 5,000 Da and their degradation kinetics in physiologically relevant media (phosphate buffer saline, PBS pH7.4, and fetal bovine serum) was assessed by the elemental analysis of the Si using inductive coupled plasma atomic emission spectroscopy (ICP-AES). The conjugation of the PEG with lowest MW to the nanovectors surface did not induce any change in the degradation kinetics in serum, but inhibited degradation and consequently the release of orthosilicic acid into buffer. When PEGs with the longer chains were evaluated, Si mass loss from the nanovectors was slowed down, and the PEGylated structures were almost fully degraded within 18 24 hours in serum and within 48 hours in PBS. The most dramatic effect was observed for high MW PEGs 3,400 and 5,000 Da, which prominently inhibited the degradation of the systems, with complete degradation achieved only after four days. For these PEGs, during the early stages of the degradation, there was a lag period of little or no Si mass loss from the nanovector. The obtained profiles were in agreement with the erosion of the nanovector surface as observed by scanning electron microscopy.

Liquid-phase deposition of thin Si films by ballistic electro-reduction

NASA Astrophysics Data System (ADS)

Ohta, T.; Gelloz, B.; Kojima, A.; Koshida, N.

2013-01-01

It is shown that the nanocryatalline silicon ballistic electron emitter operates in a SiCl4 solution without using any counter electrodes and that thin amorphous Si films are efficiently deposited on the emitting surface with no contaminations and by-products. Despite the large electrochemical window of the SiCl4 solution, electrons injected with sufficiently high energies preferentially reduce Si4+ ions at the interface. Using an emitter with patterned line emission windows, a Si-wires array can be formed in parallel. This low-temperature liquid-phase deposition technique provides an alternative clean process for power-effective fabrication of advanced thin Si film structures and devices.

Low Temperature Electrical Spin Injection from Highly Spin Polarized Co₂CrAl Heusler Alloy into p-Si.

PubMed

Kar, Uddipta; Panda, J; Nath, T K

2018-06-01

The low temperature spin accumulation in p-Si using Co2CrAl/SiO2 tunnel junction has been investigated in detail. The heterojunction has been fabricated using electron beam evaporation (EBE) technique. The 3-terminal contacts in Hanle geometry has been made for spin transport measurements. The electrical transport properties have been investigated at different isothermal conditions in the temperature range of 10-300 K. The current-voltage characteristics of the junction shows excellent rectifying magnetic diode like behaviour in lower temperature range (below 200 K). At higher temperature, the junction shows nonlinear behaviour without rectifying characteristics. We have observed spin accumulation signal in p-Si semiconductor using SiO2/Co2CrAl tunnel junction in the low temperature regime (30-100 K). Hence the highly spin polarized Full Heusler alloys compounds, like Co2CrAl etc., are very attractive and can act as efficient tunnel device for spin injection in the area of spintronics devices in near future. The estimated spin life time is τ = 54 pS and spin diffusion length inside p-Si is LSD = 289 nm at 30 K for this heterostructure.

Strong room temperature electroluminescence from lateral p-SiGe/i-Ge/n-SiGe heterojunction diodes on silicon-on-insulator substrate

NASA Astrophysics Data System (ADS)

Lin, Guangyang; Yi, Xiaohui; Li, Cheng; Chen, Ningli; Zhang, Lu; Chen, Songyan; Huang, Wei; Wang, Jianyuan; Xiong, Xihuan; Sun, Jiaming

2016-10-01

A lateral p-Si0.05Ge0.95/i-Ge/n-Si0.05Ge0.95 heterojunction light emitting diode on a silicon-on-insulator (SOI) substrate was proposed, which is profitable to achieve higher luminous extraction compared to vertical junctions. Due to the high carrier injection ratio of heterostructures and optical reflection at the SiO2/Si interface of the SOI, strong room temperature electroluminescence (EL) at around 1600 nm from the direct bandgap of i-Ge with 0.30% tensile strain was observed. The EL peak intensity of the lateral heterojunction is enhanced by ˜4 folds with a larger peak energy than that of the vertical Ge p-i-n homojunction, suggesting that the light emitting efficiency of the lateral heterojunction is effectively improved. The EL peak intensity of the lateral heterojunction, which increases quadratically with injection current density, becomes stronger for diodes with a wider i-Ge region. The CMOS compatible fabrication process of the lateral heterojunctions paves the way for the integration of the light source with the Ge metal-oxide-semiconductor field-effect-transistor.

Sulfite Reductase Protects Plants against Sulfite Toxicity1[W][OA

PubMed Central

Yarmolinsky, Dmitry; Brychkova, Galina; Fluhr, Robert; Sagi, Moshe

2013-01-01

Plant sulfite reductase (SiR; Enzyme Commission 1.8.7.1) catalyzes the reduction of sulfite to sulfide in the reductive sulfate assimilation pathway. Comparison of SiR expression in tomato (Solanum lycopersicum ‘Rheinlands Ruhm’) and Arabidopsis (Arabidopsis thaliana) plants revealed that SiR is expressed in a different tissue-dependent manner that likely reflects dissimilarity in sulfur metabolism between the plant species. Using Arabidopsis and tomato SiR mutants with modified SiR expression, we show here that resistance to ectopically applied sulfur dioxide/sulfite is a function of SiR expression levels and that plants with reduced SiR expression exhibit higher sensitivity than the wild type, as manifested in pronounced leaf necrosis and chlorophyll bleaching. The sulfite-sensitive mutants accumulate applied sulfite and show a decline in glutathione levels. In contrast, mutants that overexpress SiR are more tolerant to sulfite toxicity, exhibiting little or no damage. Resistance to high sulfite application is manifested by fast sulfite disappearance and an increase in glutathione levels. The notion that SiR plays a role in the protection of plants against sulfite is supported by the rapid up-regulation of SiR transcript and activity within 30 min of sulfite injection into Arabidopsis and tomato leaves. Peroxisomal sulfite oxidase transcripts and activity levels are likewise promoted by sulfite application as compared with water injection controls. These results indicate that, in addition to participating in the sulfate assimilation reductive pathway, SiR also plays a role in protecting leaves against the toxicity of sulfite accumulation. PMID:23221833

Discovery of a novel oocyte-specific Krüppel-associated box domain-containing zinc finger protein required for early embryogenesis in cattle.

PubMed

Hand, Jacqelyn M; Zhang, Kun; Wang, Lei; Koganti, Prasanthi P; Mastrantoni, Kristen; Rajput, Sandeep K; Ashry, Mohamed; Smith, George W; Yao, Jianbo

2017-04-01

Zinc finger (ZNF) transcription factors interact with DNA through zinc finger motifs and play important roles in a variety of cellular functions including cell growth, proliferation, development, apoptosis, and intracellular signal transduction. One-third of ZNF proteins in metazoans contain a highly conserved N-terminal motif known as the Krüppel-associated box (KRAB) domain, which acts as a potent, DNA-binding dependent transcriptional repression module. Analysis of RNA-Seq data generated from a bovine oocyte cDNA library identified a novel transcript, which encodes a KRAB-containing ZNF transcription factor (named ZNFO). Characterization of ZNFO mRNA expression revealed that it is exclusively expressed in bovine oocytes and early embryos. A GFP reporter assay demonstrated that ZNFO protein localizes specifically to the nucleus, supporting its role in transcriptional regulation. To test the role of ZNFO in early embryonic development, zygotes were generated by in vitro maturation and fertilization of oocytes, and injected with small interfering RNA (siRNA) designed to knockdown ZNFO. Cleavage rates were not affected by ZNFO siRNA injection. However, embryonic development to 8- to 16-cell stage and blastocyst stage was significantly reduced relative to the uninjected and negative control siRNA-injected embryos. Further, interaction of ZNFO with the highly conserved co-factor, KRAB-associated protein-1 (KAP1), was demonstrated, and evidence supporting transcriptional repression by ZNFO was demonstrated using a GAL4-luciferase reporter system. Results of described studies demonstrate that ZNFO is a maternally-derived oocyte-specific nuclear factor required for early embryonic development in cattle, presumably functioning by repressing transcription. Copyright © 2017 Elsevier B.V. All rights reserved.

Sequential injection system with in-line solid phase extraction and soil mini-column for determination of zinc and copper in soil leachates.

PubMed

Paluch, Justyna; Mesquita, Raquel B R; Cerdà, Víctor; Kozak, Joanna; Wieczorek, Marcin; Rangel, António O S S

2018-08-01

A sequential injection (SI) system equipped with in-line solid phase extraction column and in-line soil mini-column is proposed for determination of zinc and copper in soil leachates. The spectrophotometric determination (560 nm) is based on the reaction of both analytes with 1-(2-Pyridylazo)-2-naphthol (PAN). Zinc is determined after retaining copper on a cationic resin (Chelex100) whereas copper is determined from the difference of the absorbance measured for both analytes, introduced into the system with the use of a different channel, and zinc absorbance. The influence of several potential interferences was studied. Using the developed method, zinc and copper were determined within the concentration ranges of 0.005-0.300 and 0.011-0.200 mg L -1 , and with a relative standard deviation lower than 6.0% and 5.1%, respectively. The detection limits are 1.4 and 3.0 µg/L for determination of zinc and copper, respectively. The developed SI method was verified by the determination of both analytes in synthetic and certified reference materials of water samples, and applied to the determination of the analytes in rain water and soil leachates from laboratory scale soil core column and in-line soil mini-column. Copyright © 2018 Elsevier B.V. All rights reserved.

Quantitative measurement of delivery and gene silencing activities of siRNA polyplexes containing pyridylthiourea-grafted polyethylenimines.

PubMed

Pinel, Sophie; Aman, Emmanuel; Erblang, Felix; Dietrich, Jonathan; Frisch, Benoit; Sirman, Julien; Kichler, Antoine; Sibler, Annie-Paule; Dontenwill, Monique; Schaffner, Florence; Zuber, Guy

2014-05-28

The activity of synthetic interfering nucleic acids (siRNAs) relies on the capacity of delivery systems to efficiently transport nucleic acids into the cytosol of target cells. The pyridylthiourea-grafted 25KDa polyethylenimine (πPEI) is an excellent carrier for siRNA delivery into cells and it was extensively investigated in this report. Quantification of the siRNA-mediated gene silencing efficiency indicated that the πPEI specific delivery activity at the cell level may be measured and appears relatively constant in various cell lines. Delivery experiments assaying inhibitors of various entry pathways or concanamycin A, an inhibitor of the H(+)/ATPase vacuolar pump showed that the πPEI/siRNA polyplexes did not require any specific entry mode but strongly relied on vacuolar acidification for functional siRNA delivery. Next, πPEI polyplexes containing a siRNA targeting the transcription factor HIF-1α, known to be involved in tumor progression, were locally injected into mice xenografted with a human glioblastoma. A 55% reduction of the level of the target mRNA was observed at doses comparable to those used in vitro when the πPEI delivery activity was calculated per cell. Altogether, our study underscores the usefulness of "simple"/rough cationic polymers for siRNA delivery despite their intrinsic limitations. The study underscores as well as that bottom-up strategies make sense. The in vitro experiments can precede in vivo administration and be of high value for selection of the carrier with enhanced specific delivery activity and parallel other research aiming at improving synthetic delivery systems for resilience in the blood and for enhanced tissue-targeting capacity. Copyright © 2014 Elsevier B.V. All rights reserved.

Overview of HIT-SI Results and Plans

NASA Astrophysics Data System (ADS)

Ennis, D. A.; Akcay, C.; Hansen, C. J.; Hicks, N. K.; Hossack, A. C.; Jarboe, T. R.; Marklin, G. J.; Nelson, B. A.; Victor, B. S.

2011-10-01

Experiments in the Helicity Injected Torus-Steady Inductive (HIT-SI) device have achieved record spheromak current amplification during operations in deuterium plasmas. HIT-SI investigates steady inductive helicity injection with the aim of forming and sustaining a high-beta equilibrium in a spheromak geometry using two semi-toroidal injectors. Recent operations in deuterium plasmas have produced toroidal plasma currents greater than 50 kA, with current amplifications (Itor / Iinj) > 3 , and poloidal flux amplifications (ψpol /ψinj) > 10 . High performance deuterium discharges are achieved by initially conditioning the plasma-facing alumina surface of the HIT-SI confinement volume with helium plasmas. During subsequent deuterium operation the alumina surface strongly pumps deuterium, thereby limiting the density in the confinement volume. Additional measurements during high current deuterium discharges demonstrate reduced current and electron density fluctuations, impurity O III ion temperatures up to 50 eV and a toroidal current persistence for 0.6 ms after the injectors are shut off. Progress and plans for the HIT-SI3 configuration, with three injectors mounted on the same side of the confinement volume, will also be presented. Work supported by USDoE and ARRA.

Nanostructured Lipid Carriers as Multifunctional Nanomedicine Platform for Pulmonary Co-Delivery of Anticancer Drugs and siRNA

PubMed Central

Taratula, Oleh; Kuzmov, Andriy; Shah, Milin; Garbuzenko, Olga B.; Minko, Tamara

2013-01-01

We developed, synthesized, and tested a multifunctional nanostructured lipid nanocarrier-based system (NLCS) for efficient delivery of an anticancer drug and siRNA directly into the lungs by inhalation. The system contains: (1) nanostructured lipid carriers (NLC); (2) anticancer drug (doxorubicin or paclitaxel); (3) siRNA targeted to MRP1 mRNA as a suppressor of pump drug resistance; (4) siRNA targeted to BCL2 mRNA as a suppressor of nonpump cellular resistance and (5) a modified synthetic analog of luteinizing hormone-releasing hormone (LHRH) as a targeting moiety specific to the receptors that are overexpressed in the plasma membrane of lung cancer cells. The NLCS was tested in vitro using human lung cancer cells and in vivo utilizing mouse orthotopic model of human lung cancer. After inhalation, the proposed NLCS effectively delivered its payload into lung cancer cells leaving healthy lung tissues intact and also significantly decreasing the exposure of healthy organs when compared with intravenous injection. The NLCS showed enhanced antitumor activity when compared with intravenous treatment. The data obtained demonstrated high efficiency of proposed NLCS for tumor-targeted local delivery by inhalation of anticancer drugs and mixture of siRNAs specifically to lung cancer cells and, as a result, efficient suppression of tumor growth and prevention of adverse side effects on healthy organs. PMID:23648833

Leakage current conduction, hole injection, and time-dependent dielectric breakdown of n-4H-SiC MOS capacitors during positive bias temperature stress

NASA Astrophysics Data System (ADS)

Samanta, Piyas; Mandal, Krishna C.

2017-01-01

The conduction mechanism(s) of gate leakage current JG through thermally grown silicon dioxide (SiO2) films on the silicon (Si) face of n-type 4H-silicon carbide (4H-SiC) has been studied in detail under positive gate bias. It was observed that at an oxide field above 5 MV/cm, the leakage current measured up to 303 °C can be explained by Fowler-Nordheim (FN) tunneling of electrons from the accumulated n-4H-SiC and Poole-Frenkel (PF) emission of trapped electrons from the localized neutral traps located at ≈2.5 eV below the SiO2 conduction band. However, the PF emission current IPF dominates the FN electron tunneling current IFN at oxide electric fields Eox between 5 and 10 MV/cm and in the temperature ranging from 31 to 303 °C. In addition, we have presented a comprehensive analysis of injection of holes and their subsequent trapping into as-grown oxide traps eventually leading to time-dependent dielectric breakdown during electron injection under positive bias temperature stress (PBTS) in n-4H-SiC metal-oxide-silicon carbide structures. Holes were generated in the heavily doped n-type polycrystalline silicon (n+-polySi) gate (anode) as well as in the oxide bulk via band-to-band ionization by the hot-electrons depending on their energy and SiO2 film thickness at Eox between 6 and 10 MV/cm (prior to the intrinsic oxide breakdown field). Transport of hot electrons emitted via both FN and PF mechanisms was taken into account. On the premise of the hole-induced oxide breakdown model, the time- and charge-to-breakdown ( tBD and QBD ) of 8.5 to 47 nm-thick SiO2 films on n-4H-SiC were estimated at a wide range of temperatures. tBD follows the Arrhenius law with activation energies varying inversely with initial applied constant field Eox supporting the reciprocal field ( 1 /E ) model of breakdown irrespective of SiO2 film thicknesses. We obtained an excellent margin (6.66 to 6.33 MV/cm at 31 °C and 5.11 to 4.55 MV/cm at 303 °C) of normal operating field for a 10-year projected lifetime of 8.5 to 47 nm-thick SiO2 films on n-4H-SiC under positive bias on the n+-polySi gate. Furthermore, the projected maximum operating oxide field was little higher in metal gate devices compared to n+-polySi gate devices having an identically thick thermal SiO2 films under PBTS.

Preparation and electrical properties of Cr 2O 3 gate insulator embedded with Fe dot

NASA Astrophysics Data System (ADS)

Yokota, Takeshi; Kuribayashi, Takaaki; Murata, Shotaro; Gomi, Manabu

2008-09-01

We investigated the electrical properties of a metal (Au)/insulator (magneto-electric materials: Cr 2O 3)/magnetic materials (Fe)/tunnel layer (Cr 2O 3)/semiconductor (Si) capacitor. This capacitor shows the typical capacitance-voltage ( C- V) properties of an Si-MIS capacitor with hysteresis depending on the Fe dispersibility which is determined by the deposition condition. The C- V curve of the only sample having a 0.5 nm Fe layer was seen to have a hysteresis window with a clockwise trace, indicating that electrons have been injected into the ultra-thin Fe layer. The samples having Fe layers of other thicknesses show a counterclockwise trace, which indicates that the film has mobile ionic charges due to the dispersed Fe. These results indicated that the charge-injection site, which works as a memory, in the Cr 2O 3 can be prepared by Fe insertion, which is deposited using well-controlled conditions. The results also revealed the possibility of an MIS capacitor containing both ferromagnetic materials and an ME insulating layer in a single system.

Influence of Joule heating on current-induced domain wall depinning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moretti, Simone, E-mail: simone.moretti@usal.es; Raposo, Victor; Martinez, Eduardo

2016-06-07

The domain wall depinning from a notch in a Permalloy nanostrip on top of a SiO{sub 2}/Si substrate is studied theoretically under application of static magnetic fields and the injection of short current pulses. The influence of Joule heating on current-induced domain wall depinning is explored self-consistently by coupling the magnetization dynamics in the ferromagnetic strip to the heat transport throughout the system. Our results indicate that Joule heating plays a remarkable role in these processes, resulting in a reduction in the critical depinning field and/or in a temporary destruction of the ferromagnetic order for typically injected current pulses. Inmore » agreement with experimental observations, similar pinning-depinning phase diagrams can be deduced for both current polarities when the Joule heating is taken into account. These observations, which are incompatible with the sole contribution of spin transfer torques, provide a deeper understanding of the physics underlying these processes and establish the real scope of the spin transfer torque. They are also relevant for technological applications based on current-induced domain-wall motion along soft strips.« less

Internal Photoemission at Interfaces of ALD TaSiOx Insulating Layers Deposited on Si, InP and In0.53Ga0.47As

NASA Astrophysics Data System (ADS)

Y Chou, H.; Afanas'ev, V. V.; Thoan, N. H.; Adelmann, C.; Lin, H. C.; Houssa, M.; Stesmans, A.

2012-10-01

Electrical analysis of interfaces of (100)Si, (100)InP, and (100)In0.53Ga0.47As with TaSiOx (Ta/Si≈1) films atomic-layer deposited using SiCl4, TaCl5, and H2O precursors suggests Ta silicate as a good insulating and surface passivating layer on all three semiconductors. However, when a positive voltage is applied to the top metal electrode in a metal/ TaSiOx /semiconductor configuration, considerable hysteresis of the capacitance-voltage curves, both at 300 and 77 K, is universally observed indicating electron injection and trapping in the insulator. To shed some light on the origin of this charge instability, we analyzed interface band alignment of the studied interfaces using the spectroscopies of internal photoemission and photoconductivity measurements. The latter reveals that independently of the semiconductor substrate material, TaSiOx layers exhibit a bandgap of only 4.5±0.1 eV, typical for a Ta2O5 network. The density of electron states associated with this narrow-gap network may account for the enhanced electron injection and trapping. Furthermore, while a sufficiently high energy barrier for electrons between Si and TaSiOx (3.1±0.1 eV) is found, much lower IPE thresholds are encountered at the (100)InP/TaSiOx and (100) In0.53Ga0.47As/TaSiOx interfaces, i.e., 2.4 and 2.0 eV, respectively. The lower barrier may be related by the formation of narrow-gap In-rich interlayers between AIIIBV semiconductors and TaSiOx.

Role of the inversion layer on the charge injection in silicon nanocrystal multilayered light emitting devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tondini, S.; Dipartimento di Fisica, Informatica e Matematica, Università di Modena e Reggio Emilia, Via Campi 213/a, 41125 Modena; Pucker, G.

2016-09-07

The role of the inversion layer on injection and recombination phenomena in light emitting diodes (LEDs) is here studied on a multilayer (ML) structure of silicon nanocrystals (Si-NCs) embedded in SiO{sub 2}. Two Si-NC LEDs, which are similar for the active material but different in the fabrication process, elucidate the role of the non-radiative recombination rates at the ML/substrate interface. By studying current- and capacitance-voltage characteristics as well as electroluminescence spectra and time-resolved electroluminescence under pulsed and alternating bias pumping scheme in both the devices, we are able to ascribe the different experimental results to an efficient or inefficient minoritymore » carrier (electron) supply by the p-type substrate in the metal oxide semiconductor LEDs.« less

Non-local opto-electrical spin injection and detection in germanium at room temperature

NASA Astrophysics Data System (ADS)

Jamet, Matthieu; Rortais, Fabien; Zucchetti, Carlo; Ghirardini, Lavinia; Ferrari, Alberto; Vergnaud, Celine; Widiez, Julie; Marty, Alain; Attane, Jean-Philippe; Jaffres, Henri; George, Jean-Marie; Celebrano, Michele; Isella, Giovanni; Ciccacci, Franco; Finazzi, Marco; Bottegoni, Federico

Non-local charge carriers injection/detection schemes lie at the foundation of information manipulation in integrated systems. The next generation electronics may operate on the spin instead of the charge and germanium appears as the best hosting material to develop such spintronics for its compatibility with mainstream silicon technology and long spin lifetime at room temperature. Moreover, the energy proximity between the direct and indirect bandgaps allows for optical spin orientation. In this presentation, we demonstrate injection of pure spin currents in Ge, combined with non-local spin detection blocks at room temperature. Spin injection is performed either electrically through a magnetic tunnel junction (MTJ) or optically, by using lithographed nanostructures to diffuse the light and create an in-plane polarized electron spin population. Pure spin current detection is achieved using either a MTJ or the inverse spin-Hall effect across a Pt stripe. Supported by the ANR project SiGeSPIN #ANR-13-BS10-0002 and the CARIPLO project SEARCH-IV (Grant 2013-0623).

Transcriptome Analysis and Screening for Potential Target Genes for RNAi-Mediated Pest Control of the Beet Armyworm, Spodoptera exigua.

PubMed

Li, Hang; Jiang, Weihua; Zhang, Zan; Xing, Yanru; Li, Fei

2013-01-01

The beet armyworm, Spodoptera exigua (Hübner), is a serious pest worldwide that causes significant losses in crops. Unfortunately, genetic resources for the beet armyworm is extremely scarce. To improve these resources we sequenced the transcriptome of S. exigua representing all stages including eggs, 1(st) to 5(th) instar larvae, pupae, male and female adults using the Illumina Solexa platform. We assembled the transcriptome with Trinity that yielded 31,414 contigs. Of these contigs, 18,592 were annotated as protein coding genes by Blast searches against the NCBI nr database. It has been shown that knockdown of important insect genes by dsRNAs or siRNAs is a feasible mechanism to control insect pests. The first key step towards developing an efficient RNAi-mediated pest control technique is to find suitable target genes. To screen for effective target genes in the beet armyworm, we selected nine candidate genes. The sequences of these genes were amplified using the RACE strategy. Then, siRNAs were designed and chemically synthesized. We injected 2 µl siRNA (2 µg/µl) into the 4(th) instar larvae to knock down the respective target genes. The mRNA abundance of target genes decreased to different levels (∼20-94.3%) after injection of siRNAs. Knockdown of eight genes including chitinase7, PGCP, chitinase1, ATPase, tubulin1, arf2, tubulin2 and arf1 caused a significantly high level of mortality compared to the negative control (P<0.05). About 80% of the surviving insects in the siRNA-treated group of five genes (PGCP, chitinase1, tubulin1, tubulin2 and helicase) showed retarded development. In chitinase1-siRNA and chitinase7-siRNA administered groups, 12.5% survivors exhibited "half-ecdysis". In arf1-siRNA and arf2-siRNA groups, the body color of 15% became black 48 h after injections. In summary, the transcriptome could be a valuable genetic resource for identification of genes in S. exigua and this study provided putative targets for RNAi pest control.

Transcriptome Analysis and Screening for Potential Target Genes for RNAi-Mediated Pest Control of the Beet Armyworm, Spodoptera exigua

PubMed Central

Zhang, Zan; Xing, Yanru; Li, Fei

2013-01-01

The beet armyworm, Spodoptera exigua (Hübner), is a serious pest worldwide that causes significant losses in crops. Unfortunately, genetic resources for the beet armyworm is extremely scarce. To improve these resources we sequenced the transcriptome of S. exigua representing all stages including eggs, 1st to 5th instar larvae, pupae, male and female adults using the Illumina Solexa platform. We assembled the transcriptome with Trinity that yielded 31,414 contigs. Of these contigs, 18,592 were annotated as protein coding genes by Blast searches against the NCBI nr database. It has been shown that knockdown of important insect genes by dsRNAs or siRNAs is a feasible mechanism to control insect pests. The first key step towards developing an efficient RNAi-mediated pest control technique is to find suitable target genes. To screen for effective target genes in the beet armyworm, we selected nine candidate genes. The sequences of these genes were amplified using the RACE strategy. Then, siRNAs were designed and chemically synthesized. We injected 2 µl siRNA (2 µg/µl) into the 4th instar larvae to knock down the respective target genes. The mRNA abundance of target genes decreased to different levels (∼20–94.3%) after injection of siRNAs. Knockdown of eight genes including chitinase7, PGCP, chitinase1, ATPase, tubulin1, arf2, tubulin2 and arf1 caused a significantly high level of mortality compared to the negative control (P<0.05). About 80% of the surviving insects in the siRNA-treated group of five genes (PGCP, chitinase1, tubulin1, tubulin2 and helicase) showed retarded development. In chitinase1-siRNA and chitinase7-siRNA administered groups, 12.5% survivors exhibited “half-ecdysis”. In arf1-siRNA and arf2-siRNA groups, the body color of 15% became black 48 h after injections. In summary, the transcriptome could be a valuable genetic resource for identification of genes in S. exigua and this study provided putative targets for RNAi pest control. PMID:23823756

Pilot study of quantitative analysis of background enhancement on breast MR images: association with menstrual cycle and mammographic breast density.

PubMed

Scaranelo, Anabel M; Carrillo, Maria Claudia; Fleming, Rachel; Jacks, Lindsay M; Kulkarni, Supriya R; Crystal, Pavel

2013-06-01

To perform semiautomated quantitative analysis of the background enhancement (BE) in a cohort of patients with newly diagnosed breast cancer and to correlate it with mammographic breast density and menstrual cycle. Informed consent was waived after the research ethics board approved this study. Results of 177 consecutive preoperative breast magnetic resonance (MR) examinations performed from February to December 2009 were reviewed; 147 female patients (median age, 48 years; range, 26-86 years) were included. Ordinal values of BE and breast density were described by two independent readers by using the Breast Imaging Reporting and Data System lexicon. The BE coefficient (BEC) was calculated thus: (SI2 · 100/SI1) - 100, where SI is signal intensity, SI2 is the SI enhancement measured in the largest anteroposterior dimension in the axial plane 1 minute after the contrast agent injection, and SI1is the SI before contrast agent injection. BEC was used for the quantitative analysis of BE. Menstrual cycle status was based on the last menstrual period. The Wilcoxon rank-sum or Kruskal-Wallis test was used to compare quantitative assessment groups. Cohen weighted κ was used to evaluate agreement. Of 147 patients, 68 (46%) were premenopausal and 79 (54%) were postmenopausal. The quantitative BEC was associated with the menstrual status (BEC in premenopausal women, 31.48 ± 20.68 [standard deviation]; BEC in postmenopausal women, 25.65 ± 16.74; P = .02). The percentage of overall BE was higher when the MR imaging was performed in women in the inadequate phase of the cycle (<35 days, not 7-14 days; mean BEC, 35.7) compared with women in the postmenopausal group (P = .001). Premenopausal women had significantly higher BEC when compared with postmenopausal women (P = .03). There was no significant difference in the percentage of BE between breast density groups. Premenopausal women with breast cancer, and specifically women in the inadequate phase of the cycle, presented with higher quantitative BE than postmenopausal women. No association was found between BE and breast density.

Direct electron injection into an oxide insulator using a cathode buffer layer

PubMed Central

Lee, Eungkyu; Lee, Jinwon; Kim, Ji-Hoon; Lim, Keon-Hee; Seok Byun, Jun; Ko, Jieun; Dong Kim, Young; Park, Yongsup; Kim, Youn Sang

2015-01-01

Injecting charge carriers into the mobile bands of an inorganic oxide insulator (for example, SiO2, HfO2) is a highly complicated task, or even impossible without external energy sources such as photons. This is because oxide insulators exhibit very low electron affinity and high ionization energy levels. Here we show that a ZnO layer acting as a cathode buffer layer permits direct electron injection into the conduction bands of various oxide insulators (for example, SiO2, Ta2O5, HfO2, Al2O3) from a metal cathode. Studies of current–voltage characteristics reveal that the current ohmically passes through the ZnO/oxide-insulator interface. Our findings suggests that the oxide insulators could be used for simply fabricated, transparent and highly stable electronic valves. With this strategy, we demonstrate an electrostatic discharging diode that uses 100-nm SiO2 as an active layer exhibiting an on/off ratio of ∼107, and protects the ZnO thin-film transistors from high electrical stresses. PMID:25864642

A New Concept of Dual Fuelled SI Engines Run on Gasoline and Alcohol

NASA Astrophysics Data System (ADS)

Stelmasiak, Zdzisław

2011-06-01

The paper discusses tests results of dual-fuel spark ignition engine with multipoint injection of alcohol and gasoline, injected in area of inlet valve. Fuelling of the engine was accomplished via prototype inlet system comprising duplex injectors controlled electronically. Implemented system enables feeding of the engine with gasoline only or alcohol only, and simultaneous combustion of a mixture of the both fuels with any fraction of alcohol. The tests were performed on four cylinders, spark ignition engine of Fiat 1100 MPI type. The paper presents comparative results of dual-fuel engine test when the engine runs on changing fraction of methyl alcohol. The tests have demonstrated an advantageous effect of alcohol additive on efficiency and TCH and NOx emission of the engine, especially in case of bigger shares of the alcohol and higher engine loads.

Atomic-Scale Engineering of Abrupt Interface for Direct Spin Contact of Ferromagnetic Semiconductor with Silicon

PubMed Central

Averyanov, Dmitry V.; Karateeva, Christina G.; Karateev, Igor A.; Tokmachev, Andrey M.; Vasiliev, Alexander L.; Zolotarev, Sergey I.; Likhachev, Igor A.; Storchak, Vyacheslav G.

2016-01-01

Control and manipulation of the spin of conduction electrons in industrial semiconductors such as silicon are suggested as an operating principle for a new generation of spintronic devices. Coherent injection of spin-polarized carriers into Si is a key to this novel technology. It is contingent on our ability to engineer flawless interfaces of Si with a spin injector to prevent spin-flip scattering. The unique properties of the ferromagnetic semiconductor EuO make it a prospective spin injector into silicon. Recent advances in the epitaxial integration of EuO with Si bring the manufacturing of a direct spin contact within reach. Here we employ transmission electron microscopy to study the interface EuO/Si with atomic-scale resolution. We report techniques for interface control on a submonolayer scale through surface reconstruction. Thus we prevent formation of alien phases and imperfections detrimental to spin injection. This development opens a new avenue for semiconductor spintronics. PMID:26957146

Activation of the Nrf2-ARE pathway by siRNA knockdown of Keap1 reduces oxidative stress and provides partial protection from MPTP-mediated neurotoxicity.

PubMed

Williamson, Tracy P; Johnson, Delinda A; Johnson, Jeffrey A

2012-06-01

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that binds to the antioxidant response element, a cis-acting regulatory element that increases expression of detoxifying enzymes and antioxidant proteins. Kelch-like ECH associating protein 1 (Keap1) protein is a negative regulator of Nrf2. Previous work has shown that genetic overexpression of Nrf2 is protective in vitro and in vivo. To modulate the Nrf2-ARE system without overexpressing Nrf2, we used short interfering RNA (siRNA) directed against Keap1. Keap1 siRNA administration in primary astrocytes increased the levels of Nrf2-ARE driven genes and protected against oxidative stress. Moreover, Keap1 siRNA resulted in a persistent upregulation of the Nrf2-ARE pathway and protection against oxidative stress in primary astrocytes. Keap1 siRNA injected into the striatum was also modestly protective against MPTP-induced dopaminergic terminal damage. These data indicate that activation of endogenous intracellular levels of Nrf2 is sufficient to protect in models of oxidative stress and Parkinson's disease. Copyright © 2012 Elsevier Inc. All rights reserved.

Internal Photoemission at Interaces of ALD TaiOx Insulating Layers Deposited on Si, InP and In0.53Ga0.47As

NASA Astrophysics Data System (ADS)

Chou, H. Y.; Afanas'ev, V. V.; Thoan, N. H.; Adelmann, C.; Lin, H. C.; Houssa, M.; Stesmans, A.

2012-12-01

Electrical analysis of interfaces of (100)Si, (100)InP, and (100)In0.53Ga0.47As with TaSiOx (Ta/Si≈1) films atomic-layer deposited using SiCl4, TaCl5, and H2O precursors suggests Ta silicate as a good insulating and surface passivating layer on all three semiconductors. However, when a positive voltage is applied to the top metal electrode in a metal/ TaSiOx /semiconductor configuration, considerable hysteresis of the capacitance-voltage curves, both at 300 and 77 K, is universally observed indicating electron injection and trapping in the insulator. To shed some light on the origin of this charge instability, we analyzed interface band alignment of the studied interfaces using the spectroscopies of internal photoemission and photoconductivity measurements. The latter reveals that independently of the semiconductor substrate material, TaSiOx layers exhibit a bandgap of only 4.5±0.1 eV, typical for a Ta2O5 network. The density of electron states associated with this narrow-gap network may account for the enhanced electron injection and trapping. Furthermore, while a sufficiently high energy barrier for electrons between Si and TaSiOx (3.1±0.1 eV) is found, much lower IPE thresholds are encountered at the (100)InP/TaSiOx and (100) In0.53Ga0.47As/TaSiOx interfaces, i.e., 2.4 and 2.0 eV, respectively. The lower barrier may be related by the formation of narrow-gap In-rich interlayers between AIIIBV semiconductors and TaSiOx.

Advanced Ceramics from Preceramic Polymers Modified at the Nano-Scale: A Review

PubMed Central

Bernardo, Enrico; Fiocco, Laura; Parcianello, Giulio; Storti, Enrico; Colombo, Paolo

2014-01-01

Preceramic polymers, i.e., polymers that are converted into ceramics upon heat treatment, have been successfully used for almost 40 years to give advanced ceramics, especially belonging to the ternary SiCO and SiCN systems or to the quaternary SiBCN system. One of their main advantages is the possibility of combining the shaping and synthesis of ceramics: components can be shaped at the precursor stage by conventional plastic-forming techniques, such as spinning, blowing, injection molding, warm pressing and resin transfer molding, and then converted into ceramics by treatments typically above 800 °C. The extension of the approach to a wider range of ceramic compositions and applications, both structural and thermo-structural (refractory components, thermal barrier coatings) or functional (bioactive ceramics, luminescent materials), mainly relies on modifications of the polymers at the nano-scale, i.e., on the introduction of nano-sized fillers and/or chemical additives, leading to nano-structured ceramic components upon thermal conversion. Fillers and additives may react with the main ceramic residue of the polymer, leading to ceramics of significant engineering interest (such as silicates and SiAlONs), or cause the formation of secondary phases, significantly affecting the functionalities of the polymer-derived matrix. PMID:28788548

Mesoporous Silica Nanoparticle Delivery of Chemically Modified siRNA Against TWIST1 Leads to Reduced Tumor Burden

PubMed Central

Finlay, James; Roberts, Cai M.; Dong, Juyao; Zink, Jeffrey I.; Tamanoi, Fuyuhiko; Glackin, Carlotta A.

2015-01-01

Growth and progression of solid tumors depends on the integration of multiple pro-growth and survival signals, including the induction of angiogenesis. TWIST1 is a transcription factor whose reactivation in tumors leads to epithelial to mesenchymal transition (EMT), including increased cancer cell stemness, survival, and invasiveness. Additionally, TWIST1 drives angiogenesis via activation of IL-8 and CCL2, independent of VEGF signaling. In this work, results suggest that chemically modified siRNA against TWIST1 reverses EMT both in vitro and in vivo. siRNA delivery with a polyethyleneimine-coated mesoporous silica nanoparticle (MSN) led to reduction of TWIST1 target genes and migratory potential in vitro. In mice bearing xenograft tumors, weekly intravenous injections of the siRNA-nanoparticle complexes resulted in decreased tumor burden together with a loss of CCL2 suggesting a possible anti-angiogenic response. Therapeutic use of TWIST1 siRNA delivered via MSNs has the potential to inhibit tumor growth and progression in many solid tumor types. Chemically modified siRNA against TWIST1 was complexed to cation-coated mesoporous silica nanoparticles and tested in vitro and in vivo. In cell culture experiments, siRNA reduced expression of TWIST1 and its target genes, and reduced cell migration. In mice, injections of the siRNA-nanoparticle complex led to reduced tumor weight. Data suggest that diminished tumor burden was the result of reduced CCL2 expression and angiogenesis following TWIST1 knockdown. PMID:26115637

Annual Conference on Nuclear and Space Radiation Effects, 14th, College of William and Mary, Williamsburg, Va., July 12-15, 1977, Proceedings

NASA Technical Reports Server (NTRS)

Stahl, R. H.

1977-01-01

Topics related to processing and hardness assurance are considered, taking into account the radiation hardening of CMOS technologies, technological advances in the manufacture of radiation-hardened CMOS integrated circuits, CMOS hardness assurance through process controls and optimized design procedures, the application of operational amplifiers to hardened systems, a hard off-the-shelf SG1524 pulse width modulator, and the gamma-induced voltage breakdown anomaly in a Schottky diode. Basic mechanisms are examined, giving attention to chemical and structural aspects of the irradiation behavior of SiO2 films on silicon, experimental observations of the chemistry of the SiO2/Si interface, leakage current phenomena in irradiated SOS devices, the avalanche injection of holes into SiO2, the low-temperature radiation response of Al2O3 gate insulators, and neutron damage mechanisms in silicon at 10 K. Other subjects discussed are related to radiation effects in devices and circuits, space radiation effects, and aspects of simulation, energy deposition, and dosimetry.

Ultrasound-guided plasma rich in growth factors injections and scaffolds hasten motor nerve functional recovery in an ovine model of nerve crush injury.

PubMed

Sánchez, Mikel; Anitua, E; Delgado, D; Prado, R; Sánchez, P; Fiz, N; Guadilla, J; Azofra, J; Pompei, O; Orive, G; Ortega, M; Yoshioka, T; Padilla, S

2017-05-01

In the present study we evaluated the motor recovery process of peripheral nerve injury (PNI), based on electrophysiological and histomorphometric criteria, after treatment with plasma rich in growth factors (PRGF) injections and scaffolds in an ovine model. Three groups of sheep underwent a nerve crush lesion: the first group (n = 3) was left to recover spontaneously (SR); the second group was administered saline injections (SI; n = 5) and a third group (n = 6) received PRGF injections and scaffolds immediately after the crush injury. At post-intervention week 8, 70% of sheep in the PRGF group were CMAP-positive, with no electrophysiological response in the rest of the groups. Histomorphometric analysis 12 weeks after the surgical intervention revealed that the average axonal density of the SR (1184 ± 864 axons/µm 2 ) and SI (3109 ± 2450 axons/µm 2 ) groups was significantly inferior to the control (8427 ± 2433 axons/µm 2 ) and also inferior to the PRGF group (5276 ± 4148 axons/µm 2 ), showing no significant differences between the control and PRGF groups. The axonal size of the SR and SI groups was significantly smaller compared with the control group (18 ± 4 µm 2 ), whereas the axonal size of the PRGF group (6 ± 5 µm 2 ) did not show statistical differences from the control. Morphometry of the target muscles indicated that the PRGF group had the lowest percentage volume reduction 12 weeks after the crush injury. The PRGF group had larger muscle fibre areas than the SI and SR groups, although the differences did not reach statistical significance. Overall, these data suggest that the PRGF injections and scaffolds hastened functional axon recovery and dampened atrophy of the target muscles in an ovine model. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

PERMEABILITY PROPERTIES OF FLY ASH FORM FURNACE SORBENT INJECTION PROCESS

EPA Science Inventory

The paper discusses tests of the applicability of furnace sorbent injection (FSI) waste solids for use as synthetic waste landfill liners by measuring the mechanical strength and permeability of moisture-cured samples. SI waste solids were received from the EPA-sponsored demonstr...

Injected carrier concentration dependence of the expansion of single Shockley-type stacking faults in 4H-SiC PiN diodes

NASA Astrophysics Data System (ADS)

Tawara, T.; Matsunaga, S.; Fujimoto, T.; Ryo, M.; Miyazato, M.; Miyazawa, T.; Takenaka, K.; Miyajima, M.; Otsuki, A.; Yonezawa, Y.; Kato, T.; Okumura, H.; Kimoto, T.; Tsuchida, H.

2018-01-01

We investigated the relationship between the dislocation velocity and the injected carrier concentration on the expansion of single Shockley-type stacking faults by monitoring the electroluminescence from 4H-SiC PiN diodes with various anode Al concentrations. The injected carrier concentration was calculated using a device simulation that took into account the measured accumulated charge in the drift layer during diode turn-off. The dislocation velocity was strongly dependent on the injected hole concentration, which represents the excess carrier concentration. The activation energy of the dislocation velocity was quite small (below 0.001 eV between 310 and 386 K) over a fixed range of hole concentrations. The average threshold hole concentration required for the expansion of bar-shaped single Shockley-type stacking faults at the interface between the buffer layer and the substrate was determined to be 1.6-2.5 × 1016 cm-3 for diodes with a p-type epitaxial anode with various Al concentrations.

Abnormal bias dependence of magnetoresistance in CoFeB/MgO/Si spin-injection tunnel contacts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, June-Young; Park, Byong-Guk, E-mail: bgpark@kaist.ac.kr; Baek, Seung-heon Chris

We report a strong bias voltage dependence of magnetoresistance (MR) in CoFeB/MgO/Si spin-injection tunnel contacts using the three-terminal Hanle geometry. When a bias voltage is relatively large, the MR is composed of two characteristic signals: a conventional Hanle signal observed at a low magnetic field, which is due to the precession of injected spins, and another signal originating from the rotation of the magnetization at a larger magnetic field. In contrast, for a small bias voltage, additional signals appear at a wide range of magnetic fields, which occasionally overwhelms the conventional Hanle signals. Because the additional signals are pronounced atmore » a low bias and are significantly reduced by annealing at moderate temperatures, they can be attributed to multi-step tunneling via defect states at the interfaces or tunnel barrier. Our results demonstrate that the spin injection signal caused by the defect states can be evaluated by its bias voltage dependence.« less

A novel tyrosine-modified low molecular weight polyethylenimine (P10Y) for efficient siRNA delivery in vitro and in vivo.

PubMed

Ewe, Alexander; Przybylski, Susanne; Burkhardt, Jana; Janke, Andreas; Appelhans, Dietmar; Aigner, Achim

2016-05-28

The delivery of nucleic acids, particularly of small RNA molecules like siRNAs for the induction of RNA interference (RNAi), still represents a major hurdle with regard to their application in vivo. Possible therapeutic applications thus rely on the development of efficient non-viral gene delivery vectors. While low molecular weight polyethylenimines (PEIs) have been successfully explored, the introduction of chemical modifications offers an avenue towards the development of more efficient vectors. In this paper, we describe the synthesis of a novel tyrosine-modified low-molecular weight polyethylenimine (P10Y) for efficient siRNA complexation and delivery. The comparison with the respective parent PEI reveals that knockdown efficacies are considerably enhanced by the tyrosine modification, as determined in different reporter cell lines, without appreciable cytotoxicity. We furthermore identify optimal conditions for complex preparation as well as for storing or lyophilization of the complexes without loss of biological activity. Beyond reporter cell lines, P10Y/siRNA complexes mediate the efficient knockdown of endogenous target genes and, upon knockdown of the anti-apoptotic oncogene survivin, tumor cell inhibitory effects in different carcinoma cell lines. Pushing the system further towards its therapeutic in vivo application, we demonstrate in mice the delivery of intact siRNAs and distinct biodistribution profiles upon systemic (intravenous or intraperitoneal) injection. No adverse effects (hepatotoxicity, immunostimulation/alterations in immunophenotype, weight loss) are observed. More importantly, profound tumor-inhibitory effects in a melanoma xenograft mouse model are observed upon systemic application of P10Y/siRNA complexes for survivin knockdown, indicating the therapeutic efficacy of P10Y/siRNA complexes. Taken together, we (i) establish tyrosine-modified PEI (P10Y) as efficient platform for siRNA delivery in vitro and in vivo, (ii) identify optimal preparation and storage conditions as well as (iii) physicochemical and biological properties of P10Y complexes, and (iv) demonstrate their applicability as siRNA therapeutic in vivo (v) in the absence of adverse effects. Copyright © 2016 Elsevier B.V. All rights reserved.

Involvement of the central melanocortin system in the effects of caffeine on anxiety-like behavior in mice.

PubMed

Bhorkar, Amita A; Dandekar, Manoj P; Nakhate, Kartik T; Subhedar, Nishikant K; Kokare, Dadasaheb M

2014-01-30

To investigate the role of the melanocortin (MC) system in the framework of the central nucleus of the amygdala (CeA) in the differential effects of the adenosine receptor blocker caffeine on anxiety-like behavior, using the social interaction (SI) test. Caffeine was injected intraperitoneally, alone or in combination with alpha-melanocyte stimulating hormone (α-MSH), the MC4 receptor agonist RO27-3225 or the antagonist HS014 via the intra-CeA route. The effects of chronic (21 days) caffeine, given alone or concurrently with α-MSH, or RO27-3225, were investigated. The effects of withdrawal of these treatments on SI time were also evaluated. Furthermore, the acute effects of HS014 were investigated in different sets of caffeine-withdrawn mice. Acute injection of caffeine, RO27-3225, or α-MSH produced anxiety-like behavior. Prior treatment with α-MSH, or RO27-3225 potentiated the caffeine-induced anxiety-like behavior. Subchronic treatment with HS014 increased the SI time, which was attenuated by caffeine. Chronic administration of caffeine resulted in tolerance to caffeine's anxiogenic effect, while abrupt discontinuation of the treatment produced peak anxiety-like behavior at 72 h post-withdrawal. Concurrent administration of α-MSH, or RO27-3225 with chronic caffeine delayed the development of tolerance and prevented withdrawal-induced anxiety-like behavior. Moreover, acute treatment with HS014 at 72 h post-withdrawal attenuated the anxiety-like behavior. α-MSH, possibly via MC4 receptor in the neuroanatomical framework of the CeA, may contribute to the acute, chronic and withdrawal actions of caffeine associated with anxiety-like behavior in the neuroanatomical framework of the CeA. Copyright © 2013 Elsevier Inc. All rights reserved.

[Locally administered lentivirus-mediated siRNA inhibits wear debris-induced inflammation].

PubMed

Peng, Xiao-chun; Zhang, Xian-long; Tao, Kun; Cheng, Tao; Zhu, Jun-feng; Zeng, Bing-fang

2009-03-01

To determine the safety and efficacy of local administration of lentivirus-mediated small interfering RNA (siRNA) targeting tumor necrosis factor-alpha (TNF-alpha) in murine air pouch model. From May 2007 to April 2008 a siRNA targeting TNF-alpha and a missense siRNA were designed, and recombine lentivirus which coexpressed the green fluorescent protein (GFP) as a marker gene was constructed. Air pouches were established and stimulated by Ti-6Al-4V particles. Pouches were divided into 3 groups randomly. Lentivirus-mediated siRNA targeting TNF-alpha (TNF-alpha group) or lentivirus-mediated missense siRNA (MS group), or virus-free saline (control group) were injected into pouches respectively. Pouch membrane, peripheral blood, heart, liver, spleen, kidney, lung and brain were harvested at 28 d after transfection, and assayed for markers of inflammation using histological, molecular, immunological techniques and Xenogen in vivo imaging system (IVIS) 50 vivo bioluminescent assay system. Xenogen IVIS 50 vivo image revealed strong expression of GFP localized in pouch areas and no expression in other parts of mice both in TNF-alpha group and MS group at 4 weeks after transfection, while no expression of GFP was found in control group. By RT-PCR and ELISA, the mRNA and protein levels of TNF-alpha in TNF-alpha group decreased by 81.6% and 82.6% respectively compared to control group (P < 0.01), and decreased by 78.9% and 84.0% respectively compared to MS group (P < 0.01), whereas TNF-alpha level in peripheral blood, heart, liver, spleen, kidney, lung and brain remained invariant (P > 0.05). Less inflammatory responses (thinner pouch membrane and decreased cellular infiltration) were observed in TNF-alpha group. Efficient local delivery of lentivirus-mediated siRNA targeting TNF-alpha into modified murine air pouch can inhibit debris-induced inflammation effectively, with no systemic adverse effects.

Dependences of contraction/expansion of stacking faults on temperature and current density in 4H-SiC p–i–n diodes

NASA Astrophysics Data System (ADS)

Okada, Aoi; Nishio, Johji; Iijima, Ryosuke; Ota, Chiharu; Goryu, Akihiro; Miyazato, Masaki; Ryo, Mina; Shinohe, Takashi; Miyajima, Masaaki; Kato, Tomohisa; Yonezawa, Yoshiyuki; Okumura, Hajime

2018-06-01

To investigate the mechanism of contraction/expansion behavior of Shockley stacking faults (SSFs) in 4H-SiC p–i–n diodes, the dependences of the SSF behavior on temperature and injection current density were investigated by electroluminescence image observation. We investigated the dependences of both triangle- and bar-shaped SSFs on the injection current density at four temperature levels. All SSFs in this study show similar temperature and injection current density dependences. We found that the expansion of SSFs at a high current density was converted to contraction at a certain value as the current decreased and that the value is temperature-dependent. It has been confirmed that SSF behavior, which was considered complex or peculiar, might be explained mainly by the energy change caused by SSFs.

Top-up operation at Pohang Light Source-II

NASA Astrophysics Data System (ADS)

Hwang, I.; Huang, J. Y.; Kim, M.; Lee, B.-J.; Kim, C.; Choi, J.-Y.; Kim, M.-H.; Lee, H. S.; Moon, D.; Lee, E. H.; Kim, D.-E.; Nam, S. H.; Shin, S.; Cho, Moohyun

2014-05-01

After three years of upgrading work, PLS-II (S. Shin, Commissioning of the PLS-II, JINST, January 2013) is now successfully operating. The top-up operation of the 3 GeV linear accelerator had to be delayed because of some challenges encountered, and PLS-II was run in decay mode at the beginning in March 2012. The main difficulties encountered in the top-up operation of PLS-II are different levels between the linear accelerator and the storage ring, the 14 narrow gap in-vacuum undulators in operation, and the full energy injection by 3 GeV linear accelerator. Large vertical emittance and energy jitter of the linac were the major obstacles that called for careful control of injected beam to reduce beam loss in the storage ring during injection. The following measures were taken to resolve these problems: (1) The high resolution Libera BPM (see http://www.i-tech.si) was implemented to measure the beam trajectory and energy. (2) Three slit systems were installed to filter the beam edge. (3) De-Qing circuit was applied to the modulator system to improve the energy stability of injected beam. As a result, the radiation by beam loss during injection is reduced drastically, and the top-up mode has been successfully operating since 19th March 2013. In this paper, we describe the experimental results of the PLS-II top-up operation and the improvement plan.

Targeted knockout of TNF-α by injection of lentivirus-mediated siRNA into the subacromial bursa for the treatment of subacromial bursitis in rats.

PubMed

Wang, Yi; Li, Quan; Wei, Xianzhao; Xu, Jie; Chen, Qi; Song, Shuang; Lu, Zhe; Wang, Zimin

2015-09-01

Subacromial bursitis (SAB) is the major source of pain in rotator cuff disease. Although multiple investigations have provided support for the role of inflammatory cytokines in SAB, few have focussed on the use these cytokines in the treatment of SAB. The aim of the present study was to observe the therapeutic efficacy of lentivirus‑mediated RNA interference (RNAi) on carrageenan‑induced SAB by injecting lentivirus‑tumor necrosis factor (TNF)‑α‑RNAi expressing TNF‑α small interfering (si)RNA. Using screened siRNA segments, an siRNA was designed. A lentivirus vector expressing siRNA was established and packed as lentivirus particles. A lentivirus that expressed the negative sequence was used as a lentivirus‑negative control (NC). The carrageenan‑induced SAB model was established in 32 male Sprague‑Dawley rats. The modeled rats were randomly assigned to four groups: Lentivirus‑RNAi treatment group, lentivirus‑NC group, SAB group and phosphate‑buffered saline (PBS) blank control group. The lentivirus was injected (1x10(7) transducing units) into the subacromial bursa of the rats in the lentivirus‑RNAi group and lentivirus‑NC group, whereas 100 µl PBS was injected at the same site in the SAB group and the PBS blank control group. At 5 weeks following injection, the animals were sacrificed and venous blood was obtained. The effect of TNF‑α interference and the expression of inflammatory cytokines were determined by reverse transcription‑quantitative polymerase chain reaction, western blotting, hematoxylin and eosin staining, Van Gieson's staining and immunofluorescence. The expression of TNF‑α was decreased in the lentivirus‑TNF‑α‑RNAi group compared with that in the SAB group. Morphological observations revealed that the number of inflammatory cells were reduced and damage to tendon fibers was attenuated in this group, suggesting that the downregulation of the protein expression levels of TNF‑α‑associated nuclear factor‑κB, matrix metalloproteinase (MMP)1, MMP9, cyclooxygenase (COX)‑1 and COX‑2 may exert a therapeutic effect on inflammation of the SAB caused by rheumatoid arthritis. It was also found that the expression of stromal cell‑derived growth factor‑1 was downregulated in the lentivirus‑TNF‑α‑RNAi group. Therefore, the present study demonstrated that lentivirus‑mediated TNF‑α RNAi effectively inhibited the inflammatory response in SAB, and that injection of a lentivirus vector into the affected region is an effective way of achieving RNAi in vivo.

Biocompatible and colloidally stabilized mPEG-PE/calcium phosphate hybrid nanoparticles loaded with siRNAs targeting tumors

PubMed Central

Gao, Pei; Zhang, Xiangyu; Wang, Hongzhi; Zhang, Qinghong

2016-01-01

Calcium phosphate nanoparticles are safe and effective delivery vehicles for small interfering RNA (siRNA), as a result of their excellent biocompatibility. In this work, mPEG-PE (polyethylene glycol-L-α-phosphatidylethanolamine) was synthesized and used to prepare nanoparticles composed of mPEG-PE and calcium phosphate for siRNA delivery. Calcium phosphate and mPEG-PE formed the stable hybrid nanoparticles through self-assembly resulting from electrostatic interaction in water. The average size of the hybrid nanoparticles was approximately 53.2 nm with a negative charge of approximately −16.7 mV, which was confirmed by dynamic light scattering (DLS) measurements. The nanoparticles exhibited excellent stability in serum and could protect siRNA from ribonuclease (RNase) degradation. The cellular internalization of siRNA-loaded nanoparticles was evaluated in SMMC-7721 cells using a laser scanning confocal microscope (CLSM) and flow cytometry. The hybrid nanoparticles could efficiently deliver siRNA to cells compared with free siRNA. Moreover, the in vivo distribution of Cy5-siRNA-loaded hybrid nanoparticles was observed after being injected into tumor-bearing nude mice. The nanoparticles concentrated in the tumor regions through an enhanced permeability and retention (EPR) effect based on the fluorescence intensities of tissue distribution. A safety evaluation of the nanoparticles was performed both in vitro and in vivo demonstrating that the hybrid nanoparticle delivery system had almost no toxicity. These results indicated that the mPEG-PE/CaP hybrid nanoparticles could be a stable, safe and promising siRNA nanocarrier for anticancer therapy. PMID:26625203

Biocompatible and colloidally stabilized mPEG-PE/calcium phosphate hybrid nanoparticles loaded with siRNAs targeting tumors.

PubMed

Gao, Pei; Zhang, Xiangyu; Wang, Hongzhi; Zhang, Qinghong; Li, He; Li, Yaogang; Duan, Yourong

2016-01-19

Calcium phosphate nanoparticles are safe and effective delivery vehicles for small interfering RNA (siRNA), as a result of their excellent biocompatibility. In this work, mPEG-PE (polyethylene glycol-L-α-phosphatidylethanolamine) was synthesized and used to prepare nanoparticles composed of mPEG-PE and calcium phosphate for siRNA delivery. Calcium phosphate and mPEG-PE formed the stable hybrid nanoparticles through self-assembly resulting from electrostatic interaction in water. The average size of the hybrid nanoparticles was approximately 53.2 nm with a negative charge of approximately -16.7 mV, which was confirmed by dynamic light scattering (DLS) measurements. The nanoparticles exhibited excellent stability in serum and could protect siRNA from ribonuclease (RNase) degradation. The cellular internalization of siRNA-loaded nanoparticles was evaluated in SMMC-7721 cells using a laser scanning confocal microscope (CLSM) and flow cytometry. The hybrid nanoparticles could efficiently deliver siRNA to cells compared with free siRNA. Moreover, the in vivo distribution of Cy5-siRNA-loaded hybrid nanoparticles was observed after being injected into tumor-bearing nude mice. The nanoparticles concentrated in the tumor regions through an enhanced permeability and retention (EPR) effect based on the fluorescence intensities of tissue distribution. A safety evaluation of the nanoparticles was performed both in vitro and in vivo demonstrating that the hybrid nanoparticle delivery system had almost no toxicity. These results indicated that the mPEG-PE/CaP hybrid nanoparticles could be a stable, safe and promising siRNA nanocarrier for anticancer therapy.

Demultiplexer for wavelength division multiplexing over polymer optical fibers applicable for high-volume production

NASA Astrophysics Data System (ADS)

Fischer, Ulrich H. P.; Höll, Sebastian; Haupt, Matthias; Joncic, Mladen

2015-10-01

Polymer optical fibers (POF) offer only transmission so far with one wavelength at 650 nm. In order to increase the overall transfer rate, the key element for wavelength division multiplexing (WDM) over POF will be presented. This element is a demultiplexer (DEMUX), which was designed in polymethylmethacrylate with an optical grating on an aspherical mirror to be produced by injection molding in a further development steps. The master was produced by diamond turning as a master for injection molding replication. The results of the different simulations followed by the development steps and the measurements of the prototype are presented. This prototype is used as a DEMUX in a WDM system with four wavelengths. In the WDM system, bit-error ratio (BER) measurements with an 8.26 Gb/s cumulated data rate in an offline processed discrete multitone modulation technique have been achieved over 100 m SI-POF at a BER of 10-3.

Design and experimental investigations on six-stroke SI engine using acetylene with water injection.

PubMed

Gupta, Keshav; Suthar, Kishanlal; Jain, Sheetal Kumar; Agarwal, Ghanshyam Das; Nayyar, Ashish

2018-06-02

In the present study, a four-stroke cycle gasoline engine is redesigned and converted into a six-stroke cycle engine and experimental study has been conducted using gasoline and acetylene as fuel with water injection at the end of the recompression stroke. Acetylene has been used as an alternative fuel along with gasoline and performance of the six-stroke spark ignition (SI) engine with these two fuels has been studied separately and compared. Brake power and thermal efficiency are found to be 5.18 and 1.55% higher with acetylene as compared to gasoline in the six-stroke engine. However, thermal efficiency is found to be 45% higher with acetylene in the six-stroke engine as compared to four-stroke SI engine. The CO and HC emissions were found to be reduced by 13.33 and 0.67% respectively with acetylene as compared to gasoline due to better combustion of acetylene. The NO x emission was reduced by 5.65% with acetylene due to lower peak temperature by water injection. The experimental results showed better engine performance and emissions with acetylene as fuel in the six-stroke engine.

MICROBIAL RESPONSES TO IN SITU CHEMICAL OXIDATION, SIX-PHASE HEATING, AND STEAM INJECTION REMEDIATION TECHNOLOGIES IN GROUND WATER

EPA Science Inventory

The evaluation of microbial responses to three in situ source removal remedial technologies including permanganate-based in-situ chemical oxidation (ISCO), six-phase heating (SPH), and steam injection (SI) was performed at Cape Canaveral Air Station in Florida. The investigatio...

An albumin-mediated cholesterol design-based strategy for tuning siRNA pharmacokinetics and gene silencing.

PubMed

Bienk, Konrad; Hvam, Michael Lykke; Pakula, Malgorzata Maria; Dagnæs-Hansen, Frederik; Wengel, Jesper; Malle, Birgitte Mølholm; Kragh-Hansen, Ulrich; Cameron, Jason; Bukrinski, Jens Thostrup; Howard, Kenneth A

2016-06-28

Major challenges for the clinical translation of small interfering RNA (siRNA) include overcoming the poor plasma half-life, site-specific delivery and modulation of gene silencing. In this work, we exploit the intrinsic transport properties of human serum albumin to tune the blood circulatory half-life, hepatic accumulation and gene silencing; based on the number of siRNA cholesteryl modifications. We demonstrate by a gel shift assay a strong and specific affinity of recombinant human serum albumin (rHSA) towards cholesteryl-modified siRNA (Kd>1×10(-7)M) dependent on number of modifications. The rHSA/siRNA complex exhibited reduced nuclease degradation and reduced induction of TNF-α production by human peripheral blood mononuclear cells. The increased solubility of heavily cholesteryl modified siRNA in the presence of rHSA facilitated duplex annealing and consequent interaction that allowed in vivo studies using multiple cholesteryl modifications. A structural-activity-based screen of in vitro EGFP-silencing was used to select optimal siRNA designs containing cholesteryl modifications within the sense strand that were used for in vivo studies. We demonstrate plasma half-life extension in NMRI mice from t1/2 12min (naked) to t1/2 45min (single cholesteryl) and t1/2 71min (double cholesteryl) using fluorescent live bioimaging. The biodistribution showed increased accumulation in the liver for the double cholesteryl modified siRNA that correlated with an increase in hepatic Factor VII gene silencing of 28% (rHSA/siRNA) compared to 4% (naked siRNA) 6days post-injection. This work presents a novel albumin-mediated cholesteryl design-based strategy for tuning pharmacokinetics and systemic gene silencing. Copyright © 2016 Elsevier B.V. All rights reserved.

Gene silencing of myofibrillogenesis regulator-1 by adenovirus-delivered small interfering RNA suppresses cardiac hypertrophy induced by angiotensin II in mice.

PubMed

Dai, Wenjian; He, Weiqing; Shang, Guangdong; Jiang, Jiandong; Wang, Yiguang; Kong, Weijia

2010-11-01

Our previous studies proved that myofibrillogenesis regulator (MR)-1 has a close relationship with cardiac hypertrophy induced by ANG II. In the present study, we developed a recombinant adenoviral vector (AdSiR-MR-1) driving small interfering (si)RNA against MR-1 to evaluate its effect on cardiac hypertrophy in vivo. Cardiac hypertrophy was induced by chronic ANG II infusion in mice; AdSiR-MR-1 was administered via the jugular vein through one bolus injection. Thirteen days after the injection, viral DNA was still detectable in the heart, validating the efficiency of gene transfer. Expression levels of MR-1 mRNA and protein were increased by 2.5-fold in the heart after ANG II infusion; AdSiR-control, which contained a scrambled siRNA sequence, had no effect on them. AdSiR-MR-1 treatment abolished the upregulation of MR-1 induced by ANG II. The silencing effect of AdSiR-MR-1 was observed in many other tissues, such as the liver, lung, and kidney, except skeletal muscle. ANG II-induced cardiac hypertrophy was suppressed in mice treated with AdSiR-MR-1, as determined by echocardiography. Morphological and immnohistochemical examinations revealed that interstitial cardiac fibrosis as well as infiltrating inflammatory cells were increased after ANG II infusion; AdSiR-MR-1 greatly ameliorated these disorders. In ANG II-infused mice, MR-1 silencing also blocked the upregulation of other genes related to cardiac hypertrophy or metabolism of the extracellular matrix. In summary, our results demonstrate the feasibility of MR-1 silencing in vivo and suggest that MR-1 could be a potential new target to treat cardiac hypertrophy induced by ANG II.

Investigation of ecological parameters of four-stroke SI engine, with pneumatic fuel injection system

NASA Astrophysics Data System (ADS)

Marek, W.; Śliwiński, K.

2016-09-01

The publication presents the results of tests to determine the impact of using waste fuels, alcohol, to power the engine, on the ecological parameters of the combustion engine. Alternatively fuelled with a mixture of iso- and n-butanol, indicated with "X" and "END, and gasoline and a mixture of fuel and alcohol. The object of the study was a four-stroke engine with spark ignition designed to work with a generator. Motor power was held by the modified system of pneumatic injection using hot exhaust gases developed by Prof. Stanislaw Jarnuszkiewicz, controlled by modern mechatronic systems. Tests were conducted at a constant speed for the intended use of the engine. The subject of the research was to determine the control parameters such as ignition timing, mixture composition and the degree of exhaust gas recirculation on the ecological parameters of the engine. Tests were carried out using partially quality power control. In summary we present the findings of this phase of the study.

Sequential injection system with multi-parameter analysis capability for water quality measurement.

PubMed

Kaewwonglom, Natcha; Jakmunee, Jaroon

2015-11-01

A simple sequential injection (SI) system with capability to determine multi-parameter has been developed for the determination of iron, manganese, phosphate and ammonium. A simple and compact colorimeter was fabricated in the laboratory to be employed as a detector. The system was optimized for suitable conditions for determining each parameter by changing software program and without reconfiguration of the hardware. Under the optimum conditions, the methods showed linear ranges of 0.2-10 mg L(-1) for iron and manganese determinations, and 0.3-5.0 mg L(-1) for phosphate and ammonium determinations, with correlation coefficients of 0.9998, 0.9973, 0.9987 and 0.9983, respectively. The system provided detection limits of 0.01, 0.14, 0.004 and 0.02 mg L(-1) for iron, manganese, phosphate and ammonium, respectively. The proposed system has good precision, low chemical consumption and high throughput. It was applied for monitoring water quality of Ping river in Chiang Mai, Thailand. Recoveries of the analysis were obtained in the range of 82-119%. Copyright © 2015 Elsevier B.V. All rights reserved.

Pulse shape discrimination based on fast signals from silicon photomultipliers

NASA Astrophysics Data System (ADS)

Yu, Junhao; Wei, Zhiyong; Fang, Meihua; Zhang, Zixia; Cheng, Can; Wang, Yi; Su, Huiwen; Ran, Youquan; Zhu, Qingwei; Zhang, He; Duan, Kai; Chen, Ming; Liu, Meng

2018-06-01

Recent developments in organic plastic scintillators capable of pulse shape discrimination (PSD) enable a breakthrough in discrimination between neutrons and gammas. Plastic scintillator detectors coupled with silicon photomultipliers (SiPMs) offer many advantages, such as lower power consumption, smaller volume, and especially insensitivity to magnetic fields, compared with conventional photomultiplier tubes (PMTs). A SensL SiPM has two outputs: a standard output and a fast output. It is known that the charge injected into the fast output electrode is typically approximately 2% of the total charge generated during the avalanche, whereas the charge injected into the standard output electrode is nearly 98% of the total. Fast signals from SiPMs exhibit better performance in terms of timing and time-correlated measurements compared with standard signals. The pulse duration of a standard signal is on the order of hundreds of nanoseconds, whereas the pulse duration of the main monopole waveform of a fast signal is a few tens of nanoseconds. Fast signals are traditionally thought to be suitable for photon counting at very high speeds but unsuitable for PSD due to the partial charge collection. Meanwhile, the standard outputs of SiPMs coupled with discriminating scintillators have yielded nice PSD performances, but there have been no reports on PSD using fast signals. Our analysis shows that fast signals can also provide discrimination if the rate of charge injection into the fast output electrode is fixed for each event, even though only a portion of the charge is collected. In this work, we achieved successful PSD using fast signals; meanwhile, using a coincidence timing window of less 3 nanoseconds between the readouts from both ends of the detector reduced the influence of the high SiPM dark current. We experimentally achieved good timing performance and PSD capability simultaneously.

Chitosan layered gold nanorods as synergistic therapeutics for photothermal ablation and gene silencing in triple-negative breast cancer.

PubMed

Yang, Zhizhou; Liu, Tengfei; Xie, Yan; Sun, Zhaorui; Liu, Hongmei; Lin, Jinfeng; Liu, Changjing; Mao, Zong-Wan; Nie, Shinan

2015-10-01

Small interfering RNAs (siRNAs) are extensively studied due to their promising potential as therapeutic agents for a wide variety of diseases, including cancer. However, efficient delivery of siRNAs to target cells and tissues is problematic due to a lack of suitable delivery vehicles. In this work, we developed a layer-by-layer assembled chitosan-gold nanorods (Chit-Au NRs) siRNA delivery system to overcome biological barriers upon systemic injection. This platform was able to protect siRNAs form degradation upon exposure to ribonuclease (RNase) or serum. Confocal and intravital microscopy reveals that Chit-Au NRs/siRNAs are successfully delivered into target cells and tissue, and can efficiently escape from endosomal/lysosomal structures. Furthermore, Chit-Au NRs/siRNA were found to accumulate in high levels in tumor tissue. The delivery system was able to inhibit the oncogene expression (pyruvate kinase isozymeM2, PKM2) in MDA-MB-231 triple negative breast cancer cells, resulting in suppression of cell proliferation and migration. Moreover, the anticancer efficacy was further enhanced through NR-mediated photothermal ablation. In conclusion, the synergistic therapeutic properties of Chit-Au NRs/siRNA enable effective suppression of cancer growth. Small interfering RNA (siRNA) therapy has promising therapeutic applications, since the expression of any protein can be suppressed. However the successful implementation of siRNA has been challenging, due to rapid degradation, poor intracellular uptake and insufficient endosomal escape. Here, we have developed a gold nanorod/chitosan-based delivery vehicle for siRNA therapy. This platform successfully overcomes the afore-mentioned challenges and can simultaneously be used for photothermal therapy, due to the optical properties of gold nanorods. We show that the anticancer activity is dramatically improved by combining thermal therapy with gene silencing. Furthermore, the Au NRs carrier shows high accumulation in tumor tissue and high transfection efficiency. This manuscript has been reviewed and approved by all co-authors. The research has not been disclosed or published and is not under consideration for publication elsewhere. We would appreciate if the manuscript could be reviewed and considered for publication in Acta BIOMATERIALIA. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Extraction method of interfacial injected charges for SiC power MOSFETs

NASA Astrophysics Data System (ADS)

Wei, Jiaxing; Liu, Siyang; Li, Sheng; Song, Haiyang; Chen, Xin; Li, Ting; Fang, Jiong; Sun, Weifeng

2018-01-01

An improved novel extraction method which can characterize the injected charges along the gate oxide interface for silicon carbide (SiC) power metal-oxide-semiconductor field-effect transistors (MOSFETs) is proposed. According to the different interface situations of the channel region and the junction FET (JFET) region, the gate capacitance versus gate voltage (Cg-Vg) curve of the device can be divided into three relatively independent parts, through which the locations and the types of the charges injected in to the oxide above the interface can be distinguished. Moreover, the densities of these charges can also be calculated by the amplitudes of the shifts in the Cg-Vg curve. The correctness of this method is proved by TCAD simulations. Moreover, experiments on devices stressed by unclamped-inductive-switching (UIS) stress and negative bias temperature stress (NBTS) are performed to verify the validity of this method.

Impact of methanol-gasoline fuel blend on the fuel consumption and exhaust emission of a SI engine

NASA Astrophysics Data System (ADS)

Rifal, Mohamad; Sinaga, Nazaruddin

2016-04-01

In this study, the effect of methanol-gasoline fuel blend (M15, M30 and M50) on the fuel consumption and exhaust emission of a spark ignition engine (SI) were investigated. In the experiment, an engine four-cylinder, four stroke injection system (engine of Toyota Kijang Innova 1TR-FE) was used. Test were did to know the relation of fuel consumption and exhaust emission (CO, CO2, HC) were analyzed under the idle throttle operating condition and variable engine speed ranging from 1000 to 4000 rpm. The experimental result showed that the fuel consumption decrease with the use of methanol. It was also shown that the CO and HC emission were reduced with the increase methanol content while CO2 were increased.

Delivery of RNAi reagents in murine models of obesity and diabetes.

PubMed

Wilcox, Denise M; Yang, Ruojing; Morgan, Sherry J; Nguyen, Phong T; Voorbach, Martin J; Jung, Paul M; Haasch, Deanna L; Lin, Emily; Bush, Eugene N; Opgenorth, Terry J; Jacobson, Peer B; Collins, Christine A; Rondinone, Cristina M; Surowy, Terry; Landschulz, Katherine T

2006-11-29

RNA interference (RNAi) is an exciting new tool to effect acute in vivo knockdown of genes for pharmacological target validation. Testing the application of this technology to metabolic disease targets, three RNAi delivery methods were compared in two frequently utilized preclinical models of obesity and diabetes, the diet-induced obese (DIO) and B6.V-Lep/J (ob/ob) mouse. Intraperitoneal (i.p.) and high pressure hydrodynamic intravenous (i.v.) administration of naked siRNA, and low pressure i.v. administration of shRNA-expressing adenovirus were assessed for both safety and gene knockdown efficacy using constructs targeting cJun N-terminal kinase 1 (JNK1). Hydrodynamic delivery of siRNA lowered liver JNK1 protein levels 40% in DIO mice, but was accompanied by iatrogenic liver damage. The ob/ob model proved even more intolerant of this technique, with hydrodynamic delivery resulting in severe liver damage and death of most animals. While well-tolerated, i.p. injections of siRNA in DIO mice did not result in any knockdown or phenotypic changes in the mice. On the other hand, i.v. injected adenovirus expressing shRNA potently reduced expression of JNK1 in vivo by 95% without liver toxicity. In conclusion, i.p. and hydrodynamic injections of siRNA were ineffective and/or inappropriate for in vivo gene targeting in DIO and ob/ob mice, while adenovirus-mediated delivery of shRNA provided a relatively benign and effective method for exploring liver target silencing.

Correlation of clinical examination characteristics with three sources of chronic low back pain.

PubMed

Young, Sharon; Aprill, Charles; Laslett, Mark

2003-01-01

Research has demonstrated some progress in using a clinical examination to predict discogenic or sacroiliac (SI) joint sources of pain. No clear predictors of symptomatic lumbar zygapophysial joints have yet been demonstrated. To identify significant components of a clinical examination that are associated with symptomatic lumbar discs, zygapophysial joints and SI joints. A prospective, criterion-related concurrent validity study performed at a private radiology practice specializing in spinal diagnostics. The sample consisted of 81 patients with chronic lumbopelvic pain referred for diagnostic injections. Contingency tables were constructed for nine features of the clinical evaluation compared with the results of diagnostic injections. Statistical analysis included chi-squared test for independence, phi and odds ratios with confidence intervals. Patients received blinded clinical examinations by physical therapists, and diagnostic injections were used as the criterion standard. Significant relationships were found between discogenic pain and centralization of pain during repeated movement testing, and pain when rising from sitting. Lumbar zygapophysial joint pain was associated with absence of pain when rising from sitting. Sacroiliac joint pain was related to three or more positive pain provocation tests, pain when rising from sitting, unilateral pain and absence of lumbar pain. Significant correlations exist between clinical examination findings and symptomatic lumbar discs, zygapophysial and SI joints. The strongest relationships were seen between SI joint pain and three or more positive pain provocation tests, centralization of pain for symptomatic discs and absence of pain when rising from sitting for symptomatic lumbar zygapophysial joints.

Fabrication of injection molded sintered alpha SiC turbine components

NASA Technical Reports Server (NTRS)

Storm, R. S.; Ohnsorg, R. W.; Frechette, F. J.

1981-01-01

Fabrication of a sintered alpha silicon carbide turbine blade by injection molding is described. An extensive process variation matrix was carried out to define the optimum fabrication conditions. Variation of molding parameters had a significant impact on yield. Turbine blades were produced in a reasonable yield which met a rigid quality and dimensional specification. Application of injection molding technology to more complex components such as integral rotors is also described.

High-sensitivity silicon nanowire phototransistors

NASA Astrophysics Data System (ADS)

Tan, Siew Li; Zhao, Xingyan; Dan, Yaping

2014-08-01

Silicon nanowires (SiNWs) have emerged as a promising material for high-sensitivity photodetection in the UV, visible and near-infrared spectral ranges. In this work, we demonstrate novel planar SiNW phototransistors on silicon-oninsulator (SOI) substrate using CMOS-compatible processes. The device consists of a bipolar transistor structure with an optically-injected base region. The electronic and optical properties of the SiNW phototransistors are investigated. Preliminary simulation and experimental results show that nanowire geometry, doping densities and surface states have considerable effects on the device performance, and that a device with optimized parameters can potentially outperform conventional Si photodetectors.

Enhancement of photoluminescence from nanocrystal β-FeSi2/SiO2 composite and relaxation of thermal quenching

NASA Astrophysics Data System (ADS)

Maeda, Yoshihito

2017-05-01

We have investigated the thermal quenching behavior of photoluminescence (PL) from β-FeSi2 (β-NC) embedded in Si (β-NC/Si) and SiO2 (β-NC/SiO2). The β-NC/SiO2 composite was prepared directly from the β-NC/Si composite by selective oxidation. In the β-NC/SiO2 composite, we found an increase in the critical temperature, which indicates the relaxation of thermal quenching for PL intensity. Furthermore, we observed a clear PL spectrum including the intrinsic A band PL at 300 K; however, the PL intensity was extremely low. Rutherford backscattering spectrometry (RBS) and photocarrier injection PL (PCI-PL) measurements revealed the reason why the β-NC/Si composites were maintained after oxidation. We discussed the thermal quenching behavior of both samples on the basis of a thermal activation model of holes from valence band wells at the heterointerface and confirmed that this model was appropriate for understanding the thermal quenching of these composites.

New high-capacity, calcium-based sorbents, calcium silicate sorbents. Final report, 1993--August 31, 1994

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kenney, M.C.; Chiang, R.K.; Fillgrove, K.L.

1995-02-01

A search is being carried out for new calcium-based S0{sub 2} sorbents for induct injection. More specifically, a search is being carried out for induct injection calcium silicate sorbents that are highly cost effective. The objectives for the current year include the study of sorbents made from Ca(OH){sub 2}, from mixtures of Ca(OH){sub 2} and SiO{sub 2}, and from portland cement. They also include the study of sorbents made from model compounds. During this year, sorbents prepared from Ca(OH){sub 2} and from mixtures of Ca(OH){sub 2} and fumed SiO{sub 2} were investigated. The results show that very good SiO{sub 2}-modifiedmore » Ca(OH){sub 2} sorbents in which the Si-to-Ca reactant ratio is low can be prepared from Ca(OH){sub 2} and fumed SiO{sub 2}. Sorbents prepared from Ca(OH){sub 2} and natural SiO{sub 2} or natural SiO{sub 2} sources were also studied. The results obtained show that very good SiO{sub 2}-modified Ca(OH){sub 2} sorbents and calcium silicate hydrate sorbents, C-S-H sorbents, can be prepared from Ca(OH){sub 2} and diatomite, pumice or perlite, minerals that are readily available. In addition. sorbents prepared from Ca{sub 3}SiO{sub 5} and {beta}-Ca{sub 2}SiO{sub 4} and from mixtures of these compounds and SiO{sub 2} were studied. The results secured demonstrate that very good C-S-H rich sorbents can be prepared from these compounds and from mixtures of them with SiO{sub 2}. They also provide information useful for interpreting the cement sorbent results. Sorbents prepared from cement and from mixtures of cement and natural SiO{sub 2} or SiO{sub 2} sources were investigated as well. The results secured show that cement and mixtures of it with diatomite, pumice or perlite rapidly yield excellent sorbents with the proper reaction conditions.« less

Intravitreal Controlled Release of Dexamethasone from Engineered Microparticles of Porous Silicon Dioxide

PubMed Central

Wang, Chengyun; Hou, Huiyuan; Nan, Kaihui; Sailor, Michael J; Freeman, William R.; Cheng, Lingyun

2014-01-01

Dexamethasone is a glucocorticoid that is widely used in the ophthalmic arena. The recent FDA approved dexamethasone implant can provide a three month efficacy but with high rate of drug related cataract and high intraocular pressure (IOP). It seems that higher steroid in aqueous humor and around lens may be associated with these complications based on clinical fact that higher IOP was observed with intravitreal triamcinolone acetonide (TA) than with subtenon TA. We hypothesize that placing a sustained dexamethasone release system near back of the eye through a fine needle can maximize efficacy while mitigate higher rate of IOP rise and cataract. To develop a sustained intravitreal dexamethasone delivery system, porous silicon dioxide (pSiO2) microparticles were fabricated and functionalized with amines as well as carboxyl groups. Dexamethasone was conjugated to pSiO2 through the Steglich Esterificaion Reaction between hydroxyl of dexamethasone and carboxyl groups on the pSiO2. The drug loading was confirmed by Fourier transform infrared spectroscopy (FTIR) and loading efficiency was quantitated using thermogravimetric analysis (TGA). In vitro release was conducted for three months and dexamethasone was confirmed in the released samples using liquid chromatography-tandem mass spectrometry (LC/MS/MS). A pilot ocular safety and determination of vitreous drug level was performed in rabbit eyes. The drug loading study demonstrated that loading efficiency was from 5.96% to 10.77% depending on the loading reaction time, being higher with longer loading reaction time before reaching saturation around 7 days. In vitro drug release study revealed that dexamethasone release from pSiO2 particles was sustainable for over 90 days and was 80 days longer than free dexamethasone or infiltration-loaded pSiO2 particle formulation in the same setting. Pilot in vivo study demonstrated no sign of ocular adverse reaction in rabbit eyes following a single 3 mg intravitreal injection and free drug level at 2-week was 107.23+/−10.54 ng/mL that is well above the therapeutic level but only around 20% level of dexamethasone released from OZURDEX ® (dexamethasone intravitreal implant) in a rabbit eye model. In conclusion, dexamethasone is able to covalently load to the pSiO2 particles and provide sustained drug release for at least 3 months in vitro. Intravitreal injection of these particles were well tolerated in rabbit eyes and free drug level in vitreous at 2-week was well above the therapeutic level. PMID:25446320

Realisation of magnetically and atomically abrupt half-metal/semiconductor interface: Co2FeSi0.5Al0.5/Ge(111)

PubMed Central

Nedelkoski, Zlatko; Kuerbanjiang, Balati; Glover, Stephanie E.; Sanchez, Ana M.; Kepaptsoglou, Demie; Ghasemi, Arsham; Burrows, Christopher W.; Yamada, Shinya; Hamaya, Kohei; Ramasse, Quentin M.; Hasnip, Philip J.; Hase, Thomas; Bell, Gavin R.; Hirohata, Atsufumi; Lazarov, Vlado K.

2016-01-01

Halfmetal-semiconductor interfaces are crucial for hybrid spintronic devices. Atomically sharp interfaces with high spin polarisation are required for efficient spin injection. In this work we show that thin film of half-metallic full Heusler alloy Co2FeSi0.5Al0.5 with uniform thickness and B2 ordering can form structurally abrupt interface with Ge(111). Atomic resolution energy dispersive X-ray spectroscopy reveals that there is a small outdiffusion of Ge into specific atomic planes of the Co2FeSi0.5Al0.5 film, limited to a very narrow 1 nm interface region. First-principles calculations show that this selective outdiffusion along the Fe-Si/Al atomic planes does not change the magnetic moment of the film up to the very interface. Polarized neutron reflectivity, x-ray reflectivity and aberration-corrected electron microscopy confirm that this interface is both magnetically and structurally abrupt. Finally, using first-principles calculations we show that this experimentally realised interface structure, terminated by Co-Ge bonds, preserves the high spin polarization at the Co2FeSi0.5Al0.5/Ge interface, hence can be used as a model to study spin injection from half-metals into semiconductors. PMID:27869132

Substrate driven photochemistry of CdSe quantum dot films: charge injection and irreversible transformations on oxide surfaces.

PubMed

Tvrdy, Kevin; Kamat, Prashant V

2009-04-23

The photochemical behavior of CdSe quantum dots anchored to different surfaces was probed through their deposition on glass, SiO2, and TiO2 films. Following visible light irradiation under ambient conditions, CdSe quantum dots deposited on semiconducting TiO2 surface degraded, where no such degradation was observed when deposited on inert SiO2 surface or glass. Fluorescence decay and transient absorption experiments confirmed that charge injection from excited CdSe into TiO2 occurs with an apparent rate constant of 5.62 x 10(8) s(-1) and is the primary event responsible for photodegradation. In the presence of air, injected electrons are scavenged by surface adsorbed oxygen leaving behind reactive holes which induce anodic corrosion of CdSe quantum dots. In a vacuum environment, minimal CdSe degradation was observed as electron scavenging by oxygen is replaced with charge recombination between injected electrons and holes in CdSe nanocrystals. Spectroscopic measurements presented in this study highlight the role of both substrate and medium in dictating the photochemistry of CdSe quantum dots.

The Contribution of Prohibitin 1 to Prostate Cancer Chemoresistance

DTIC Science & Technology

2015-10-01

ceramide-PEG5K in normal BALB/c mice after i.v. injection. The siRNA was labeled with near infrared (NIR) dye DY647. (B) Ex vivo fluorescence image of...ceramide-PEG5K (Right) siRNA NPs at 18 h. The siRNA was labeled with dye DY547. (Scale bar, 10 μm.) Zhu et al. PNAS | June 23, 2015 | vol. 112 | no...Woodrow KA, et al. (2009) Intravaginal gene silencing using biodegradable polymer nanoparticles densely loaded with small-interfering RNA. Nat Mater

Functionalized Dendrimer-Based Delivery of Angiotensin Type 1 Receptor siRNA for Preserving Cardiac Function Following Infarction

PubMed Central

Liu, Jie; Gu, Catherine; Cabigas, E. Bernadette; Pendergrass, Karl D.; Brown, Milton E.; Luo, Ying; Davis, Michael E.

2013-01-01

Cardiovascular disease (CVD) is the leading cause of death throughout the world and much pathology is associated with upregulation of inflammatory genes. Gene silencing using RNA interference is a powerful tool in regulating gene expression, but its application in CVDs has been prevented by the lack of efficient delivery systems. We report here the development of tadpole dendrimeric materials for siRNA delivery in a rat ischemia-reperfusion (IR) model. Angiotensin II (Ang II) type 1 receptor (AT1R), the major receptor that mediates most adverse effects of Ang II, was chosen to be the silencing targeting. Among the three tadpole dendrimers synthesized, the oligo-arginine conjugated dendrimer loaded with siRNA demonstrated effective down-regulation in AT1R expression in cardiomyocytes in vitro. When the dendrimeric material was applied in vivo, the siRNA delivery prevented the increase in AT1R levels and significantly improved cardiac function recovery compared to saline injection or empty dendrimer treated groups after IR injury. These experiments demonstrate a potential treatment for dysfunction caused by IR injury and may represent an alternative to AT1R blockade. PMID:23433774

Determination of essential elements in beverages, herbal infusions and dietary supplements using a new straightforward sequential approach based on flame atomic absorption spectrometry.

PubMed

Gómez-Nieto, Beatriz; Gismera, Mª Jesús; Sevilla, Mª Teresa; Procopio, Jesús R

2017-03-15

A simple method based on FAAS was developed for the sequential multi-element determination of Cu, Zn, Mn, Mg and Si in beverages and food supplements with successful results. The main absorption lines for Cu, Zn and Si and secondary lines for Mn and Mg were selected to carry out the measurements. The sample introduction was performed using a flow injection system. Using the choice of the absorption line wings, the upper limit of the linear range increased up to 110mgL -1 for Mg, 200mgL -1 for Si and 13mgL -1 for Zn. The determination of the five elements was carried out, in triplicate, without the need of additional sample dilutions and/or re-measurements, using less than 3.5mL of sample to perform the complete analysis. The LODs were 0.008mgL -1 for Cu, 0.017mgL -1 for Zn, 0.011mgL -1 for Mn, 0.16mgL -1 for Si and 0.11mgL -1 for Mg. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of SiO 2/Si 3N 4 dielectric distributed Bragg reflectors (DDBRs) for Alq 3/NPB thin-film resonant cavity organic light emitting diodes

NASA Astrophysics Data System (ADS)

Lei, Po-Hsun; Wang, Shun-Hsi; Juang, Fuh Shyang; Tseng, Yung-Hsin; Chung, Meng-Jung

2010-05-01

In this article, we report on the effect of SiO 2/Si 3N 4 dielectric distributed Bragg reflectors (DDBRs) for Alq 3/NPB thin-film resonant cavity organic light emitting diode (RCOLED) in increasing the light output intensity and reducing the linewidth of spontaneous emission spectrum. The optimum DDBR number is found as 3 pairs. The device performance will be bad by further increasing or decreasing the number of DDBR. As compared to the conventional Alq 3/NPB thin-film organic light emitting diode (OLED), the Alq 3/NPB thin-film RCOLED with 3-pair DDBRs has the superior electrical and optical characteristics including a forward voltage of 6 V, a current efficiency of 3.4 cd/A, a luminance of 2715 cd/m 2 under the injection current density of 1000 A/m 2, and a full width at half maximum (FWHM) of 12 nm for emission spectrum over the 5-9 V bias range. These results represent that the Alq 3/NPB thin-film OLED with DDBRs shows a potential as the light source for plastic optical fiber (POF) communication system.

Leakage current conduction and reliability assessment of passivating thin silicon dioxide films on n-4H-SiC

NASA Astrophysics Data System (ADS)

Samanta, Piyas; Mandal, Krishna C.

2016-09-01

We have analyzed the mechanisms of leakage current conduction in passivating silicon dioxide (SiO2) films grown on (0 0 0 1) silicon (Si) face of n-type 4H-SiC (silicon carbide). It was observed that the experimentally measured gate current density in metal-oxide-silicon carbide (MOSiC) structures under positive gate bias at an oxide field Eox above 5 MV/cm is comprised of Fowler-Nordheim (FN) tunneling of electrons from the accumulated n-4H-SiC and Poole-Frenkel (PF) emission of trapped electrons from the localized neutral traps in the SiO2 gap, IFN and IPF, respectively at temperatures between 27 and 200 °C. In MOSiC structures, PF mechanism dominates FN tunneling of electrons from the accumulation layer of n-4H-SiC due to high density (up to 1013 cm-2) of carbon-related acceptor-like traps located at about 2.5 eV below the SiO2 conduction band (CB). These current conduction mechanisms were taken into account in studying hole injection/trapping into 10 nm-thick tunnel oxide on the Si face of 4H-SiC during electron injection from n-4H-SiC under high-field electrical stress with positive bias on the heavily doped n-type polysilicon (n+-polySi) gate at a wide range of temperatures between 27 and 200 °C. Holes were generated in the n+-polySi anode material by the hot-electrons during their transport through thin oxide films at oxide electric fields Eox from 5.6 to 8.0 MV/cm (prior to the intrinsic oxide breakdown field). Time-to-breakdown tBD of the gate dielectric was found to follow reciprocal field (1/E) model irrespective of stress temperatures. Despite the significant amount of process-induced interfacial electron traps contributing to a large amount of leakage current via PF emission in thermally grown SiO2 on the Si-face of n-4H-SiC, MOSiC devices having a 10 nm-thick SiO2 film can be safely used in 5 V TTL logic circuits over a period of 10 years.

Synthesis of silicon containing materials using liquid hydrosilane compositions through direct injection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Srinivasan, Guruvenket; Sailer, Robert A.; Hoey, Justin

An apparatus and a non-vapor-pressure dependent method of chemical vapor deposition of Si based materials using direct injection of liquid hydrosilane(s) are presented. Liquid silane precursor solutions may also include metal, non-metal or metalloid dopants, nanomaterials and solvents. An illustrative apparatus has a precursor solution and carrier gas system, atomizer and deposit head with interior chamber and a hot plate supporting the substrate. Atomized liquid silane precursor solutions and carrier gas moves through a confined reaction zone that may be heated and the aerosol and vapor are deposited on a substrate to form a thin film. The substrate may bemore » heated prior to deposition. The deposited film may be processed further with thermal or laser processing.« less

Top-up operation at Pohang Light Source-II

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hwang, I.; Huang, J. Y.; Kim, M.

2014-05-15

After three years of upgrading work, PLS-II (S. Shin, Commissioning of the PLS-II, JINST, January 2013) is now successfully operating. The top-up operation of the 3 GeV linear accelerator had to be delayed because of some challenges encountered, and PLS-II was run in decay mode at the beginning in March 2012. The main difficulties encountered in the top-up operation of PLS-II are different levels between the linear accelerator and the storage ring, the 14 narrow gap in-vacuum undulators in operation, and the full energy injection by 3 GeV linear accelerator. Large vertical emittance and energy jitter of the linac weremore » the major obstacles that called for careful control of injected beam to reduce beam loss in the storage ring during injection. The following measures were taken to resolve these problems: (1) The high resolution Libera BPM (see http://www.i-tech.si ) was implemented to measure the beam trajectory and energy. (2) Three slit systems were installed to filter the beam edge. (3) De-Qing circuit was applied to the modulator system to improve the energy stability of injected beam. As a result, the radiation by beam loss during injection is reduced drastically, and the top-up mode has been successfully operating since 19th March 2013. In this paper, we describe the experimental results of the PLS-II top-up operation and the improvement plan.« less

Injection molding ceramics to high green densities

NASA Technical Reports Server (NTRS)

Mangels, J. A.; Williams, R. M.

1983-01-01

The injection molding behavior of a concentrated suspension of Si powder in wax was studied. It was found that the injection molding behavior was a function of the processing techniques used to generate the powder. Dry ball-milled powders had the best molding behavior, while air classified and impact-milled powders demonstrated poorer injection moldability. The relative viscosity of these molding batches was studied as a function of powder properties: distribution shape, surface area, packing density, and particle morphology. The experimental behavior, in all cases, followed existing theories. The relative viscosity of an injection molding composition composed of dry ball-milled powders could be expressed using Farris' relation.

Strong visible electroluminescence from silicon nanocrystals embedded in a silicon carbide film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huh, Chul, E-mail: chuh@etri.re.kr; Kim, Tae-Youb; Ahn, Chang-Geun

2015-05-25

We report the strong visible light emission from silicon (Si) nanocrystals (NCs) embedded in a Si carbide (SiC) film. Compared to Si NC light-emitting diode (LED) by employing the Si nitride (SiN{sub x}) film as a surrounding matrix, the turn-on voltage of the Si NC LED with the SiC film was significantly decreased by 4 V. This was attributed to a smaller barrier height for injecting the electrons into the Si NCs due to a smaller band gap of SiC film than a SiN{sub x} film. The electroluminescence spectra increases with increasing forward voltage, indicating that the electrons are efficiently injectedmore » into the Si NCs in the SiC film. The light output power shows a linear increase with increasing forward voltage. The light emission originated from the Si NCs in a SiC film was quite uniform. The power efficiency of the Si NC LED with the SiC film was 1.56 times larger than that of the Si NC LED with the SiN{sub x} film. The Si NCs in a SiC film show unique advantages and are a promising candidate for application in optical devices.« less

Silencing hyperoxia-induced C/EBPα in neonatal mice improves lung architecture via enhanced proliferation of alveolar epithelial cells

PubMed Central

Yang, Guang; Hinson, Maurice D.; Bordner, Jessica E.; Lin, Qing S.; Fernando, Amal P.; La, Ping; Wright, Clyde J.

2011-01-01

Postnatal lung development requires proliferation and differentiation of specific cell types at precise times to promote proper alveolar formation. Hyperoxic exposure can disrupt alveolarization by inhibiting cell growth; however, it is not fully understood how this is mediated. The transcription factor CCAAT/enhancer binding protein-α (C/EBPα) is highly expressed in the lung and plays a role in cell proliferation and differentiation in many tissues. After 72 h of hyperoxia, C/EBPα expression was significantly enhanced in the lungs of newborn mice. The increased C/EBPα protein was predominantly located in alveolar type II cells. Silencing of C/EBPα with a transpulmonary injection of C/EBPα small interfering RNA (siRNA) prior to hyperoxic exposure reduced expression of markers of type I cell and differentiation typically observed after hyperoxia but did not rescue the altered lung morphology at 72 h. Nevertheless, when C/EBPα hyperoxia-exposed siRNA-injected mice were allowed to recover for 2 wk in room air, lung epithelial cell proliferation was increased and lung morphology was restored compared with hyperoxia-exposed control siRNA-injected mice. These data suggest that C/EBPα is an important regulator of postnatal alveolar epithelial cell proliferation and differentiation during injury and repair. PMID:21571903

Hybrid AlGaN-SiC Avalanche Photodiode for Deep-UV Photon Detection

NASA Technical Reports Server (NTRS)

Aslam, Shahid; Herrero, Federico A.; Sigwarth, John; Goldsman, Neil; Akturk, Akin

2010-01-01

The proposed device is capable of counting ultraviolet (UV) photons, is compatible for inclusion into space instruments, and has applications as deep- UV detectors for calibration systems, curing systems, and crack detection. The device is based on a Separate Absorption and Charge Multiplication (SACM) structure. It is based on aluminum gallium nitride (AlGaN) absorber on a silicon carbide APD (avalanche photodiode). The AlGaN layer absorbs incident UV photons and injects photogenerated carriers into an underlying SiC APD that is operated in Geiger mode and provides current multiplication via avalanche breakdown. The solid-state detector is capable of sensing 100-to-365-nanometer wavelength radiation at a flux level as low as 6 photons/pixel/s. Advantages include, visible-light blindness, operation in harsh environments (e.g., high temperatures), deep-UV detection response, high gain, and Geiger mode operation at low voltage. Furthermore, the device can also be designed in array formats, e.g., linear arrays or 2D arrays (micropixels inside a superpixel).

Electrical spin injection, transport, and detection in graphene-hexagonal boron nitride van der Waals heterostructures: progress and perspectives

NASA Astrophysics Data System (ADS)

Gurram, M.; Omar, S.; van Wees, B. J.

2018-07-01

The current research in graphene spintronics strives for achieving a long spin lifetime, and efficient spin injection and detection in graphene. In this article, we review how hexagonal boron nitride (hBN) has evolved as a crucial substrate, as an encapsulation layer, and as a tunnel barrier for manipulation and control of spin lifetimes and spin injection/detection polarizations in graphene spin valve devices. First, we give an overview of the challenges due to conventional SiO2/Si substrate for spin transport in graphene followed by the progress made in hBN based graphene heterostructures. Then we discuss in detail the shortcomings and developments in using conventional oxide tunnel barriers for spin injection into graphene followed by introducing the recent advancements in using the crystalline single/bi/tri-layer hBN tunnel barriers for an improved spin injection and detection which also can facilitate two-terminal spin valve and Hanle measurements at room temperature, and are of technological importance. A special case of bias induced spin polarization of contacts with exfoliated and chemical vapour deposition (CVD) grown hBN tunnel barriers is also discussed. Further, we give our perspectives on utilizing graphene-hBN heterostructures for future developments in graphene spintronics.

I-V and C-V Characterization of a High-Responsivity Graphene/Silicon Photodiode with Embedded MOS Capacitor.

PubMed

Luongo, Giuseppe; Giubileo, Filippo; Genovese, Luca; Iemmo, Laura; Martucciello, Nadia; Di Bartolomeo, Antonio

2017-06-27

We study the effect of temperature and light on the I-V and C-V characteristics of a graphene/silicon Schottky diode. The device exhibits a reverse-bias photocurrent exceeding the forward current and achieves a photoresponsivity as high as 2.5 A / W . We show that the enhanced photocurrent is due to photo-generated carriers injected in the graphene/Si junction from the parasitic graphene/SiO₂/Si capacitor connected in parallel to the diode. The same mechanism can occur with thermally generated carriers, which contribute to the high leakage current often observed in graphene/Si junctions.

GaAs/AlGaAs core multishell nanowire-based light-emitting diodes on Si.

PubMed

Tomioka, Katsuhiro; Motohisa, Junichi; Hara, Shinjiroh; Hiruma, Kenji; Fukui, Takashi

2010-05-12

We report on integration of GaAs nanowire-based light-emitting-diodes (NW-LEDs) on Si substrate by selective-area metalorganic vapor phase epitaxy. The vertically aligned GaAs/AlGaAs core-multishell nanowires with radial p-n junction and NW-LED array were directly fabricated on Si. The threshold current for electroluminescence (EL) was 0.5 mA (current density was approximately 0.4 A/cm(2)), and the EL intensity superlinearly increased with increasing current injections indicating superluminescence behavior. The technology described in this letter could help open new possibilities for monolithic- and on-chip integration of III-V NWs on Si.

Gate oxide thickness dependence of the leakage current mechanism in Ru/Ta2O5/SiON/Si structures

NASA Astrophysics Data System (ADS)

Ťapajna, M.; Paskaleva, A.; Atanassova, E.; Dobročka, E.; Hušeková, K.; Fröhlich, K.

2010-07-01

Leakage conduction mechanisms in Ru/Ta2O5/SiON/Si structures with rf-sputtered Ta2O5 with thicknesses ranging from 13.5 to 1.8 nm were systematically studied. Notable reaction at the Ru/Ta2O5 interface was revealed by capacitance-voltage measurements. Temperature-dependent current-voltage characteristics suggest the bulk-limited conduction mechanism in all metal-oxide-semiconductor structures. Under gate injection, Poole-Frenkel emission was identified as a dominant mechanism for 13.5 nm thick Ta2O5. With an oxide thickness decreasing down to 3.5 nm, the conduction mechanism transforms to thermionic trap-assisted tunnelling through the triangular barrier. Under substrate injection, the dominant mechanism gradually changes with decreasing thickness from thermionic trap-assisted tunnelling to trap-assisted tunnelling through the triangular barrier; Poole-Frenkel emission was not observed at all. A 0.7 eV deep defect level distributed over Ta2O5 is assumed to be responsible for bulk-limited conduction mechanisms and is attributed to H-related defects or oxygen vacancies in Ta2O5.

A novel blood-pooling MR contrast agent: Carboxymethyl-diethylaminoethyl dextran magnetite.

PubMed

Sonoda, Akinaga; Nitta, Norihisa; Tsuchiya, Keiko; Nitta-Seko, Ayumi; Ohta, Shinichi; Otani, Hideji; Murata, Kiyoshi

2016-12-01

Gadofosveset trisodium is available as a prolonged pooling vascular contrast agent for magnetic resonance imaging. As gadolinium (Gd)-based agents may increase the risk for nephrogenic systemic fibrosis in patients with severe renal insufficiency, the present study synthesized carboxymethyl-diethylaminoethyl dextran magnetite (CMEADM) particles as a blood-pooling, non-Gd‑based contrast agent. CMEADM particles carry a negative or positive charge due to the binding of amino and carboxyl groups to the hydroxyl group of dextran. The present study evaluated whether the degree of charge alters the blood‑pooling time. The evaluation was performed by injecting four groups of three Japanese white rabbits each with CMEADM‑, CMEADM2‑, CMEADM+ (surface charges: ‑10.4, ‑41.0 and +9.6 mV, respectively) or with ultrasmall superparamagnetic iron oxide (USPIO; ‑11.5 mV). The relative signal intensity (SIrel) of each was calculated using the following formula: SIrel = (SI post‑contrast ‑ SI pre‑contrast / SI pre‑contrast) x 100. Following injection with the CMEADMs, but not with USPIO, the in vivo pooling time was prolonged to >300 min. No significant differences were attributable to the electric charge among the CMEADM‑, CMEADM2‑ or and CMEADM+ particles when analyzed with analysis of variance and Tukey's HSD test. Taken together, all three differently‑charged CMEADM2 particles exhibited prolonged vascular enhancing effects, compared with the USPIO. The degree of charge of the contrast agents used in the present study did not result in alteration of the prolonged blood pooling time.

Targeted delivery of siRNA to macrophages for anti-inflammatory treatment.

PubMed

Kim, Sang-Soo; Ye, Chunting; Kumar, Priti; Chiu, Isaac; Subramanya, Sandesh; Wu, Haoquan; Shankar, Premlata; Manjunath, N

2010-05-01

Inflammation mediated by tumor necrosis factor-alpha (TNF-alpha) and the associated neuronal apoptosis characterizes a number of neurologic disorders. Macrophages and microglial cells are believed to be the major source of TNF-alpha in the central nervous system (CNS). Here, we show that suppression of TNF-alpha by targeted delivery of small interfering RNA (siRNA) to macrophage/microglial cells dramatically reduces lipopolysaccharide (LPS)-induced neuroinflammation and neuronal apoptosis in vivo. Because macrophage/microglia express the nicotinic acetylcholine receptor (AchR) on their surface, we used a short AchR-binding peptide derived from the rabies virus glycoprotein (RVG) as a targeting ligand. This peptide was fused to nona-D-arginine residues (RVG-9dR) to enable siRNA binding. RVG-9dR was able to deliver siRNA to induce gene silencing in macrophages and microglia cells from wild type, but not AchR-deficient mice, confirming targeting specificity. Treatment with anti-TNF-alpha siRNA complexed to RVG-9dR achieved efficient silencing of LPS-induced TNF-alpha production by primary macrophages and microglia cells in vitro. Moreover, intravenous injection with RVG-9dR-complexed siRNA in mice reduced the LPS-induced TNF-alpha levels in blood as well as in the brain, leading to a significant reduction in neuronal apoptosis. These results demonstrate that RVG-9dR provides a tool for siRNA delivery to macrophages and microglia and that suppression of TNF-alpha can potentially be used to suppress neuroinflammation in vivo.

Simultaneous Tc-99m skeletal and In-111 hip arthrographic scintimaging complementing contrast radiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wellman, H.N.; Uri, B.G.; Stiner, P.

1984-01-01

Prosthetic hip replacement has become a frequent procedure with femoral component (FC) loosening occurring frequently at a rate of 24% at 7 yrs post arthroplasty. Pain may occur from a variety of causes and identification of loosening as the cause is critical. Experience with radiographic contrast arthrography (XA) alone has often resulted in equivocal studies because of confusion caused by the radio-opaque glue-bone interface and adjacent radiolucency of the FC. Radionuclide arthrography (RA) with Tc-99m Sulfur Colloid (SC) has been previously shown to improve the efficiency of FC loosening determination. However, with extravasation or other confusing patterns of tracer distributionmore » more precise localization relative to skeletal structure is required with RA. Simultaneous use of RA using In-111 (IN) chloride (0.2 mCi) injected with contrast at XA superimposed on prior injected TC-99m MDP (20 mCi) skeletal imaging (SI) has considerably improved interpretation and complemented XA, correlated with surgery. Fifty RA and XA patients have been studied: 18 with SC alone, 7 with SC and IN in the joint space simultaneously and 25 with IN RA and SI. Simultaneous joint injection RA with IN and SC demonstrated exactly the same pattern with no translocation of IN. Thirty patients had surgery with 20 loose FC verified; all loose by RA but only 16 by XA plus 2 false positives. Also simultaneous SI has shown unreliable criteria for FC loosening. Thus, addition of simultaneous RA and SI for FC evaluation is a valuable adjunct in 20% of patients in the performance of arthrography.« less

Europium Silicide – a Prospective Material for Contacts with Silicon

PubMed Central

Averyanov, Dmitry V.; Tokmachev, Andrey M.; Karateeva, Christina G.; Karateev, Igor A.; Lobanovich, Eduard F.; Prutskov, Grigory V.; Parfenov, Oleg E.; Taldenkov, Alexander N.; Vasiliev, Alexander L.; Storchak, Vyacheslav G.

2016-01-01

Metal-silicon junctions are crucial to the operation of semiconductor devices: aggressive scaling demands low-resistive metallic terminals to replace high-doped silicon in transistors. It suggests an efficient charge injection through a low Schottky barrier between a metal and Si. Tremendous efforts invested into engineering metal-silicon junctions reveal the major role of chemical bonding at the interface: premier contacts entail epitaxial integration of metal silicides with Si. Here we present epitaxially grown EuSi2/Si junction characterized by RHEED, XRD, transmission electron microscopy, magnetization and transport measurements. Structural perfection leads to superb conductivity and a record-low Schottky barrier with n-Si while an antiferromagnetic phase invites spin-related applications. This development opens brand-new opportunities in electronics. PMID:27211700

Europium Silicide - a Prospective Material for Contacts with Silicon.

PubMed

Averyanov, Dmitry V; Tokmachev, Andrey M; Karateeva, Christina G; Karateev, Igor A; Lobanovich, Eduard F; Prutskov, Grigory V; Parfenov, Oleg E; Taldenkov, Alexander N; Vasiliev, Alexander L; Storchak, Vyacheslav G

2016-05-23

Metal-silicon junctions are crucial to the operation of semiconductor devices: aggressive scaling demands low-resistive metallic terminals to replace high-doped silicon in transistors. It suggests an efficient charge injection through a low Schottky barrier between a metal and Si. Tremendous efforts invested into engineering metal-silicon junctions reveal the major role of chemical bonding at the interface: premier contacts entail epitaxial integration of metal silicides with Si. Here we present epitaxially grown EuSi2/Si junction characterized by RHEED, XRD, transmission electron microscopy, magnetization and transport measurements. Structural perfection leads to superb conductivity and a record-low Schottky barrier with n-Si while an antiferromagnetic phase invites spin-related applications. This development opens brand-new opportunities in electronics.

Processing of sintered alpha SiC

NASA Technical Reports Server (NTRS)

Storm, R. S.

1984-01-01

Processing methods of sintered alpha SiC for engine applications are developed in a cost effective manner, using a submicron sized powder blended with sintering aids (boron and carbon). The processes for forming a green powder compact, such as dry pressing, cold isostatic pressing and green machining, slip casting, aqueous extrusion, plastic extrusion, and injection molding, are described. Dry pressing is the simplest route to component fabrication, and is carried out at approximately 10,000 psi pressure, while in the cold isostatic method the pressure could go as high as 20,000 psi. Surfactants are added to control settling rates and casting characteristics in the slip casting. The aqueous extrusion process is accomplished by a hydraulic ram forcing the aqueous mixture through a die. The plastic forming processes of extrusion and injection molding offer the potential of greater diversity in shape capacity. The physical properties of sintered alpha SiC (hardness, Young's modulus, shear modulus, and thermal diffusivity) are extensively tested. Corrosion resistance test results of silicon carbide are included.

Preeruption conditions and timing of dacite-andesite magma mixing in the 2.2 ka eruption at Mount Rainier

NASA Astrophysics Data System (ADS)

Venezky, D. Y.; Rutherford, M. J.

1997-01-01

Analytical, field, and experimental evidence demonstrate that the Mount Rainier tephra layer C (2.2 ka) preserves a magma mixing event between an andesitic magma (whole rock SiO2 content of 57-60 wt %) and a dacitic magma (whole rock SiO2 content of 65±1 wt %). The end-member andesite (a mix of an injected and chamber andesite) and dacite can be characterized on the basis of the homogeneity of the matrix glass and phenocryst rim compositions. Many pumices, however, contain mixtures of the end-members. The end-member dacite contains a microlite-free matrix glass with 74-77 wt % SiO2, orthopyroxene rims of Mg57-64, clinopyroxene rims of Mg66-74, and plagioclase rim anorthite contents of An45-65. The temperature and oxygen fugacity, from Fe-Ti oxide compositions, are 930±10°C and 0.5-0.75 log units above NNO. The mixed andesite contains Mg73-84 orthopyroxene rims, Mg73-78 clinopyroxene rims, An78-84 plagioclase rims, and Mg67-74 amphibole rims. The temperature from Fe-Ti oxides, hornblendeplagioclase, and two-pyroxene geothermometry is 1060±15°C, and the oxygen fugacity is approximately one log unit above NNO for the injected andesite. The chamber andesite is estimated to be a magma with a ˜64-65 wt % SiO2 melt at 980°C and a NNO oxygen fugacity. We conclude that the andesitic and dacitic magmas are from separate magma storage regions (at >7 km and ˜2.4 km) due to differences in the bimodal whole rock, matrix glass, and phenocryst compositions and the presence or absence of stable hornblende. The time involved from the mixing event through the eruption is limited to a period of 4-5 days based on Fe-Ti oxide reequilibration, phenocryst growth rates, and hornblende breakdown. The eruption sequence is interpreted as having been initiated by an injection of the 1060±15°C andesitic magma into the ˜980°C (>7 km) andesite storage region. The mixed andesitic magma then intersected a shallow, ˜2.4 km, dacitic storage system on its way toward the surface. The eruption became more dacitic over time, and the final products some show evidence of partial reequilibration between the andesite and dacite.

Retinal degeneration is delayed by tissue factor pathway inhibitor-2 in RCS rats and a sodium-iodate-induced model in rabbits.

PubMed

Obata, R; Yanagi, Y; Tamaki, Y; Hozumi, K; Mutoh, M; Tanaka, Y

2005-04-01

To investigate the in vivo effects of tissue factor pathway inhibitor 2 (TFPI-2), which stimulates proliferation of retinal pigment epithelial cells, but not the proliferation of fibroblast and vascular endothelial cells in vitro, on retinal degeneration using a sodium-iodate (SI)-induced model in rabbits and Royal Collage of Surgeons (RCS) rats. 79 microg of recombinant TFPI-2 (rTFPI-2) or vehicle alone was injected intravitreously to 18 eyes of 12 pigmented rabbits a day after 20 mg/kg of SI was intravenously administered. Retinal function was assessed 4, 7, 14, and 21 days after the injection by analysing amplitudes of the c-wave of a bright flash electroretinogram. Additionally, 10 microg of rTFPI-2 or vehicle alone was injected intravitreously to 11 eyes of RCS rats at both 3 and 4 weeks old, then the retina was examined histologically at 5 weeks old. The rTFPI-2-treated eyes in rabbits showed a significantly less decrease in the relative amplitude of the c-wave than control eyes on days 4 and 7. The thickness of the outer nuclear layer was significantly thicker and the vacuole in the photoreceptor layer was less frequently observed in the rTFPI-2-treated RCS rats than the controls. Intravitreal injection of TFPI-2 rescues SI-induced retinal degeneration in rabbits and naturally occurring retinal degeneration in RCS rats at least partly. These results may suggest that this compound can be utilized in the treatment of retinal degeneration.

The Effect of Si and Al Concentration Ratios on the Removal of U(VI) under Hanford Site 200 Area Conditions-12115

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katsenovich, Yelena; Gonzalez, Nathan; Moreno-Pastor, Carol

2012-07-01

Injection of reactive gases, such as NH{sub 3}, is an innovative technique to mitigate uranium contamination in soil for a vadose zone (VZ) contaminated with radionuclides. A series of experiments were conducted to examine the effect of the concentration ratio of silicon to aluminum in the presence of various bicarbonate concentrations on the coprecipitation process of U(VI). The concentration of Al in all tests remained unchanged at 2.8 mM. Experiments showed that the removal efficiency of uranium was not significantly affected by the different bicarbonate and U(VI) concentrations tested. For the lower Si:Al molar ratios of 2:1 and 18:1, themore » removal efficiency of uranium was relatively low (≤ 8%). For the Si:Al molar ratio of 35:1, the removal efficiency of uranium was increased to an average of ∼82% for all bicarbonate concentrations tested. At higher Si:Al molar ratios (53:1 and above), a relatively high removal efficiency of U(VI), approximately 85% and higher, was observed. These results demonstrate that the U(VI) removal efficiency is more affected by the Si:Al molar ratio than by the bicarbonate concentration in solution. The results of this experiment are promising for the potential implementation of NH{sub 3} gas injection for the remediation of U(VI) -contaminated VZ. (authors)« less

Geometrical confinement of Gd(DOTA) molecules within mesoporous silicon nanoconstructs for MR imaging of cancer

PubMed Central

Gizzatov, Ayrat; Stigliano, Cinzia; Ananta, Jeyerama S.; Sethi, Richa; Xu, Rong; Guven, Adem; Ramirez, Maricela; Shen, Haifa; Sood, Anil; Ferrari, Mauro; Wilson, Lon J.; Liu, Xuewu; Decuzzi, Paolo

2015-01-01

Porous silicon has been used for the delivery of therapeutic and imaging agents in several biomedical applications. Here, mesoporous silicon nanoconstructs (SiMPs) with a discoidal shape and a sub-micrometer size (1,000 × 400 nm) have been conjugated with gadolinium-tetraazacyclododecane tetraacetic acid Gd(DOTA) molecules and proposed as contrast agents for Magnetic Resonance Imaging. The surface of the SiMPs with different porosities – small pore (SP: ~ 5 nm) and huge pore (HP: ~ 40 nm) – and of bulk, non-porous silica beads (1,000 nm in diameter) have been modified with covalently attached (3-aminopropyl)triethoxysilane (APTES) groups, conjugated with DOTA molecules, and reacted with an aqueous solution of GdCl3. The resulting Gd(DOTA) molecules confined within the small pores of the Gd-SiMPs achieve longitudinal relaxivities r1 of ~ 17 (mM·s)−1, which is 4 times greater than for free Gd(DOTA). This enhancement is ascribed to the confinement and stable chelation of Gd(DOTA) molecules within the SiMP mesoporous matrix. The resulting nanoconstructs possess no cytotoxicity and accumulate in ovarian tumors up to 2% of the injected dose per gram tissue, upon tail vein injection. All together this data suggests that Gd-SiMPs could be efficiently used for MR vascular imaging in cancer and other diseases. PMID:24931336

Geometrical confinement of Gd(DOTA) molecules within mesoporous silicon nanoconstructs for MR imaging of cancer.

PubMed

Gizzatov, Ayrat; Stigliano, Cinzia; Ananta, Jeyerama S; Sethi, Richa; Xu, Rong; Guven, Adem; Ramirez, Maricela; Shen, Haifa; Sood, Anil; Ferrari, Mauro; Wilson, Lon J; Liu, Xuewu; Decuzzi, Paolo

2014-09-28

Porous silicon has been used for the delivery of therapeutic and imaging agents in several biomedical applications. Here, mesoporous silicon nanoconstructs (SiMPs) with a discoidal shape and a sub-micrometer size (1000×400nm) have been conjugated with gadolinium-tetraazacyclododecane tetraacetic acid Gd(DOTA) molecules and proposed as contrast agents for Magnetic Resonance Imaging. The surface of the SiMPs with different porosities - small pore (SP: ∼5nm) and huge pore (HP: ∼40nm) - and of bulk, non-porous silica beads (1000nm in diameter) have been modified with covalently attached (3-aminopropyl)triethoxysilane (APTES) groups, conjugated with DOTA molecules, and reacted with an aqueous solution of GdCl3. The resulting Gd(DOTA) molecules confined within the small pores of the Gd-SiMPs achieve longitudinal relaxivities r1 of ∼17 (mMs)(-)(1), which is 4 times greater than for free Gd(DOTA). This enhancement is ascribed to the confinement and stable chelation of Gd(DOTA) molecules within the SiMP mesoporous matrix. The resulting nanoconstructs possess no cytotoxicity and accumulate in ovarian tumors up to 2% of the injected dose per gram tissue, upon tail vein injection. All together this data suggests that Gd-SiMPs could be efficiently used for MR vascular imaging in cancer and other diseases. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

High-performance silicon nanowire bipolar phototransistors

NASA Astrophysics Data System (ADS)

Tan, Siew Li; Zhao, Xingyan; Chen, Kaixiang; Crozier, Kenneth B.; Dan, Yaping

2016-07-01

Silicon nanowires (SiNWs) have emerged as sensitive absorbing materials for photodetection at wavelengths ranging from ultraviolet (UV) to the near infrared. Most of the reports on SiNW photodetectors are based on photoconductor, photodiode, or field-effect transistor device structures. These SiNW devices each have their own advantages and trade-offs in optical gain, response time, operating voltage, and dark current noise. Here, we report on the experimental realization of single SiNW bipolar phototransistors on silicon-on-insulator substrates. Our SiNW devices are based on bipolar transistor structures with an optically injected base region and are fabricated using CMOS-compatible processes. The experimentally measured optoelectronic characteristics of the SiNW phototransistors are in good agreement with simulation results. The SiNW phototransistors exhibit significantly enhanced response to UV and visible light, compared with typical Si p-i-n photodiodes. The near infrared responsivities of the SiNW phototransistors are comparable to those of Si avalanche photodiodes but are achieved at much lower operating voltages. Compared with other reported SiNW photodetectors as well as conventional bulk Si photodiodes and phototransistors, the SiNW phototransistors in this work demonstrate the combined advantages of high gain, high photoresponse, low dark current, and low operating voltage.

NIMROD simulations and physics assessment of possible designs for a next generation Steady Inductive Helicity Injection HIT device

NASA Astrophysics Data System (ADS)

Penna, James; Morgan, Kyle; Grubb, Isaac; Jarboe, Thomas

2017-10-01

The Helicity Injected Torus - Steady Inductive 3 (HIT-SI3) experiment forms and maintains spheromaks via Steady Inductive Helicity Injection (SIHI) using discrete injectors that inject magnetic helicity via a non-axisymmetric perturbation and drive toroidally symmetric current. Newer designs for larger SIHI-driven spheromaks incorporate a set of injectors connected to a single external manifold to allow more freedom for the toroidal structure of the applied perturbation. Simulations have been carried out using the NIMROD code to assess the effectiveness of various imposed mode structures and injector schema in driving current via Imposed Dynamo Current Drive (IDCD). The results are presented here for varying flux conserver shapes on a device approximately 1.5 times larger than the current HIT-SI3 experiment. The imposed mode structures and spectra of simulated spheromaks are analyzed in order to examine magnetic structure and stability and determine an optimal regime for IDCD sustainment in a large device. The development of scaling laws for manifold operation is also presented, and simulation results are analyzed and assessed as part of the development path for the large scale device.

Injectable Chitosan/β-Glycerophosphate System for Sustained Release: Gelation Study, Structural Investigation, and Erosion Tests.

PubMed

Dalmoro, Annalisa; Abrami, Michela; Galzerano, Barbara; Bochicchio, Sabrina; Barba, Anna Angela; Grassi, Mario; Larobina, Domenico

2017-01-01

Hydrogels can constitute reliable delivery systems of drugs, including those based on nucleic acids (NABDs) such as small interfering ribonucleic acid (siRNA). Their nature, structure, and response to physiological or external stimuli strongly influence the delivery mechanisms of entrapped active molecules, and, in turn, their possible uses in pharmacological and biomedical applications. In this study, a thermo-gelling chitosan/β-glycero-phosphate system has been optimized in order to assess its use as injectable system able to: i) gelling at physiological pH and temperature, and ii) modulate the release of included active ingredients. To this aim, we first analyzed the effect of acetic acid concentration on the gelation temperature. We then found the "optimized composition", namely, the one in which the Tgel is equal to the physiological temperature. The resulting gel was tested, by low field nuclear magnetic resonance (LF-NMR), to evaluate its average mesh-size, which can affect release kinetics of loaded drug. Finally, films of gelled chitosan, loaded with a model drug, have been tested in vitro to monitor their characteristic times, i.e. diffusion and erosion time, when they are exposed to a medium mimicking a physiological environment (buffer solution at pH 7.4). Results display that the optimized system is deemed to be an ideal candidate as injectable gelling material for a sustained release. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

All-printed diode operating at 1.6 GHz

PubMed Central

Sani, Negar; Robertsson, Mats; Cooper, Philip; Wang, Xin; Svensson, Magnus; Andersson Ersman, Peter; Norberg, Petronella; Nilsson, Marie; Nilsson, David; Liu, Xianjie; Hesselbom, Hjalmar; Akesso, Laurent; Fahlman, Mats; Crispin, Xavier; Engquist, Isak; Berggren, Magnus; Gustafsson, Göran

2014-01-01

Printed electronics are considered for wireless electronic tags and sensors within the future Internet-of-things (IoT) concept. As a consequence of the low charge carrier mobility of present printable organic and inorganic semiconductors, the operational frequency of printed rectifiers is not high enough to enable direct communication and powering between mobile phones and printed e-tags. Here, we report an all-printed diode operating up to 1.6 GHz. The device, based on two stacked layers of Si and NbSi2 particles, is manufactured on a flexible substrate at low temperature and in ambient atmosphere. The high charge carrier mobility of the Si microparticles allows device operation to occur in the charge injection-limited regime. The asymmetry of the oxide layers in the resulting device stack leads to rectification of tunneling current. Printed diodes were combined with antennas and electrochromic displays to form an all-printed e-tag. The harvested signal from a Global System for Mobile Communications mobile phone was used to update the display. Our findings demonstrate a new communication pathway for printed electronics within IoT applications. PMID:25002504

Band line-up determination at p- and n-type Al/4H-SiC Schottky interfaces using photoemission spectroscopy

NASA Astrophysics Data System (ADS)

Kohlscheen, J.; Emirov, Y. N.; Beerbom, M. M.; Wolan, J. T.; Saddow, S. E.; Chung, G.; MacMillan, M. F.; Schlaf, R.

2003-09-01

The band lineup of p- and n-type 4H-SiC/Al interfaces was determined using x-ray photoemission spectroscopy (XPS). Al was deposited in situ on ex situ cleaned SiC substrates in several steps starting at 1.2 Å up to 238 Å nominal film thickness. Before growth and after each growth step, the sample surface was characterized in situ by XPS. The analysis of the spectral shifts indicated that during the initial deposition stages the Al films react with the ambient surface contamination layer present on the samples after insertion into vacuum. At higher coverage metallic Al clusters are formed. The band lineups were determined from the analysis of the core level peak shifts and the positions of the valence bands maxima (VBM) depending on the Al overlayer thickness. Shifts of the Si 2p and C 1s XPS core levels occurred to higher (lower) binding energy for the p-(n-)type substrates, which was attributed to the occurrence of band bending due to Fermi-level equilibration at the interface. The hole injection barrier at the p-type interface was determined to be 1.83±0.1 eV, while the n-type interface revealed an electron injection barrier of 0.98±0.1 eV. Due to the weak features in the SiC valence bands measured by XPS, the VBM positions were determined using the Si 2p peak positions. This procedure required the determination of the Si 2p-to-VBM binding energy difference (99.34 eV), which was obtained from additional measurements.

Mitogen Activated Protein Kinase Phosphatase-1 (MKP-1) in Retinal Ischemic Preconditioning

PubMed Central

Dreixler, John C.; Bratton, Anthony; Du, Eugenie; Shaikh, Afzhal R.; Savoie, Brian; Michael, Alexander; Marcet, Marcus; Roth, Steven

2011-01-01

We previously described the phenomenon of retinal ischemic preconditioning (IPC) and we have shown the role of various signaling proteins in the protective pathways, including the mitogen-activated protein kinase p38. In this study we examined the role in IPC of mitogen-activated protein kinase phosphatase-1 (MKP-1), which inactivates p38. Ischemia was produced by elevation of intraocular pressure above systolic arterial blood pressure in adult Wistar rats. Preconditioning was produced by transient retinal ischemia for 5 min, 24 h prior to ischemia. Small interfering RNA (siRNA) to MKP-1 or a control non-silencing siRNA, was injected into the vitreous 6 h prior to IPC. Recovery was assessed by electroretinography (ERG) and histology. The a- and b-waves, and oscillatory potentials (OPs), measured before and 1 week after ischemia, were then normalized relative to pre-ischemic baseline, and corrected for diurnal variation in the normal non-ischemic eye. The P2, or post-photoreceptor component of the ERG (which reflects function of the rod bipolar cells in the inner retina), was derived using the Hood-Birch model. MKP-1 was localized in specific retinal cells using immunohistochemistry; levels of mitogen-activated protein kinases were measured using Western blotting. Injection of siRNA to MKP-1 significantly attenuated the protective effect of IPC as reflected by decreased recovery of the electroretinogram a- and b-waves and the P2 after ischemia. The injection of siRNA to MKP-1 reduced the number of cells in the retinal ganglion cell and outer nuclear layers after IPC and ischemia. Blockade of MKP-1 by siRNA also increased the activation of p38 at 24 h following IPC. MKP-1 siRNA did not alter the levels of phosphorylated jun N-terminal kinase (JNK) or extracellular signal-regulated kinase (ERK) after IPC. The results suggest the involvement of dual-specificity phosphatase MKP-1 in IPC and that MKP-1 is involved in IPC by regulating levels of activated MAPK p38. PMID:21094639

Ge/graded-SiGe multiplication layers for low-voltage and low-noise Ge avalanche photodiodes on Si

NASA Astrophysics Data System (ADS)

Miyasaka, Yuji; Hiraki, Tatsurou; Okazaki, Kota; Takeda, Kotaro; Tsuchizawa, Tai; Yamada, Koji; Wada, Kazumi; Ishikawa, Yasuhiko

2016-04-01

A new structure is examined for low-voltage and low-noise Ge-based avalanche photodiodes (APDs) on Si, where a Ge/graded-SiGe heterostructure is used as the multiplication layer of a separate-absorption-carrier-multiplication structure. The Ge/SiGe heterojunction multiplication layer is theoretically shown to be useful for preferentially enhancing impact ionization for photogenerated holes injected from the Ge optical-absorption layer via the graded SiGe, reflecting the valence band discontinuity at the Ge/SiGe interface. This property is effective not only for the reduction of operation voltage/electric field strength in Ge-based APDs but also for the reduction of excess noise resulting from the ratio of the ionization coefficients between electrons and holes being far from unity. Such Ge/graded-SiGe heterostructures are successfully fabricated by ultrahigh-vacuum chemical vapor deposition. Preliminary pin diodes having a Ge/graded-SiGe multiplication layer act reasonably as photodetectors, showing a multiplication gain larger than those for diodes without the Ge/SiGe heterojunction.

On-Line 1D and 2D PLOT/LC-ESI-MS Using 10 μm i.d. Poly(styrene–divinylbenzene) Porous Layer Open Tubular (PLOT) Columns For Ultrasensitive Proteomic Analysis

PubMed Central

Luo, Quanzhou; Yue, Guihua; Valaskovic, Gary A; Gu, Ye; Wu, Shiaw-Lin; Karger, Barry L.

2008-01-01

Following on our recent work, on-line one dimensional (1D) and two dimensional (2D) PLOT/LC-ESI-MS platforms using 3.2 m × 10 μm i.d. poly(styrenedivinylbenzene) (PS-DVB) porous layer open tubular (PLOT) columns have been developed to provide robust, high performance and ultrasensitive proteomic analysis. Using a PicoClear tee, the dead volume connection between a 50 μm i.d. PS-DVB monolithic microSPE column and the PLOT column was minimized. The microSPE/PLOT column assembly provided a separation performance similar to that obtained with direct injection onto the PLOT column at a mobile phase flow rate of 20 nL/min. The trace analysis potential of the platform was evaluated using an in-gel tryptic digest sample of a gel fraction (15 to 40 kDa) of a cervical cancer (SiHa) cell line. As an example of the sensitivity of the system, ∼2.5 ng of protein in 2 μL solution, an amount corresponding to 20 SiHa cells, was subjected to on-line microSPE-PLOT/LC-ESIMS/MS analysis using a linear ion trap MS. 237 peptides associated with 163 unique proteins were identified from a single analysis when using stringent criteria associated with a false positive rate less than 1% . The number of identified peptides and proteins increased to 638 and 343, respectively, as the injection amount was raised to ∼45 ng of protein, an amount corresponding to 350 SiHa cells. In comparison, only 338 peptides and 231 unique proteins were identified (false positive rate again less than 1%) from 750 ng of protein from the identical gel fraction, an amount corresponding to 6000 SiHa cells, using a typical 15 cm × 75 μm i.d. packed capillary column. The greater sensitivity, higher recovery, and higher resolving power of the PLOT column resulted in the increased number of identifications from only ∼5% of the injected sample amount. The resolving power of the microSPE/PLOT assembly was further extended by 2D chromatography via combination of the high-efficiency reversed phase PLOT column with strong cation exchange chromatography (SCX). As an example, 1071 peptides associated with 536 unique proteins were identified from 75 ng of protein from the same gel fraction, an amount corresponding to 600 cells, using 5 ion exchange fractions in online 2D SCX-PLOT/LC-MS. The 2D system, implemented in an automated format, led to simple and robust operation for proteomic analysis. These promising results demonstrate the potential of the PLOT column for ultratrace analysis. PMID:17625912

The role of melanin concentrating hormone (MCH) in the central chemoreflex: a knockdown study by siRNA in the lateral hypothalamus in rats.

PubMed

Li, Ningjing; Nattie, Eugene; Li, Aihua

2014-01-01

Melanin concentrating hormone (MCH), a neuropeptide produced mainly in neurons localized to the lateral hypothalamic area (LHA), has been implicated in the regulation of food intake, energy balance, sleep state, and the cardiovascular system. Hypothalamic MCH neurons also have multisynaptic connections with diaphragmatic motoneurons and project to many central chemoreceptor sites. However, there are few studies of MCH involvement in central respiratory control. To test the hypothesis that MCH plays a role in the central chemoreflex, we induced a down regulation of MCH in the central nervous system by knocking down the MCH precursor (pMCH) mRNA in the LHA using a pool of small interfering RNA (siRNA), and measured the resultant changes in breathing, metabolic rate, body weight, and blood glucose levels in conscious rats. The injections of pMCH-siRNA into the LHA successfully produced a ∼ 62% reduction of pMCH mRNA expression in the LHA and a ∼ 43% decrease of MCH levels in the cerebrospinal fluid relative to scrambled-siRNA treatment (P = 0.006 and P = 0.02 respectively). Compared to the pretreatment baseline and the scrambled-siRNA treated control rats, knockdown of MCH resulted in: 1) an enhanced hypercapnic chemoreflex (∼ 42 & 47% respectively; P < 0.05) only in wakefulness; 2) a decrease in body weight and basal glucose levels; and 3) an unchanged metabolic rate. Our results indicate that MCH participates not only in the regulation of glucose and sleep-wake homeostasis but also the vigilance-state dependent regulation of the central hypercapnic chemoreflex and respiratory control.

An innovative system for supplying air and fuel mixture to a combustion chamber of an engine

NASA Astrophysics Data System (ADS)

Saikumar, G. R. Bharath

2018-04-01

Conventional carburetors are being used since decades to ensure that the desired ratio of air and fuel enters the combustion chamber for combustion for the purpose of generating power in an Spark Ignition(SI) internal combustion engine. However to increase the efficiency, the carburetor system is gradually being replaced by fuel injection systems. Fuel injection systems use injectors to supply pressurized fuel into the combustion chamber. Owing to the high initial and maintenance cost, carburetors are still ruling in the low cost vehicle domain. An innovative concept is conceived, which is an alternative method to the carburetor system to supply the air and fuel mixture to a combustion chamber of an engine. This system comprises of an inner hollow cylinder with minute holes drilled along its length with an outer cylinder capable of sliding along its length or its longitudinal axis. This system is placed in the venturi instead of the conventional carburetor system. Fuel enters from the bottom inlet of the inner cylinder and flows out through the holes provided along its length. The fuel flow from the inner cylinder is dependent on the size and the number of holes exposed at that instance by the sliding outer cylinder which in turn is connected to the throttle or accelerator.

Caveolin-1 siRNA increases the pulmonary microvascular and alveolar epithelial permeability in rats.

PubMed

Gao, Chengjin; Li, Rongrong; Huan, Jingning; Li, Wei

2011-01-01

Increased pulmonary microvascular and epithelial permeability are important contributors to pulmonary edema in acute lung injury. In this study, we used small interfering RNA (siRNA) to knock down caveolin-1 expression in rat lungs and to confirm the important role of caveolin-1 in regulating pulmonary edema. After pulmonary injection of siRNA against caveolin-1 messenger RNA incorporated in liposomes with three concentrations of 0.4, 0.8, and 1.2 mg/kg, the gene silencing rate and the effects of caveolin-1 siRNA on aquaporin (AQP)-1, AQP-5, and epithelial sodium channel (ENaC) were detected. For pulmonary permeability analysis, Evans blue fluorimetry, ratios of albumin concentrations between blood and bronchoalveolar lavage, and wet/dry weight ratios were measured. The impacts of caveolin-1 suppression on interendothelial junctions were evaluated by the performance of electron microscopy and the analysis of vascular endothelial (VE)-cadherin Western blot. Alveolar wall thickness analysis and chest fluoroscopy were performed to determine the pulmonary edema degree. After 72 hours of injection, the gene silencing rate of caveolin-1 siRNA is about 87%. AQP-1, AQP-5, ENaC-α, ENaC-β, ENaC-γ, and VE-cadherin protein levels were decreased by 63%, 66%, 80%, 90%, 89%, and 50%, respectively. Caveolin-1 siRNA also resulted in increasing microvascular and epithelial permeability and pulmonary edema. These data suggest that caveolin-1 plays an important part in regulating the pulmonary permeability by modifying AQP-1, AQP-5, ENaC, and VE-cadherin.

Strong electroluminescence from SiO{sub 2}-Tb{sub 2}O{sub 3}-Al{sub 2}O{sub 3} mixed layers fabricated by atomic layer deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rebohle, L., E-mail: l.rebohle@hzdr.de; Braun, M.; Wutzler, R.

2014-06-23

We report on the bright green electroluminescence (EL) with power efficiencies up to 0.15% of SiO{sub 2}-Tb{sub 2}O{sub 3}-mixed layers fabricated by atomic layer deposition and partly co-doped with Al{sub 2}O{sub 3}. The electrical, EL, and breakdown behavior is investigated as a function of the Tb and the Al concentration. Special attention has been paid to the beneficial role of Al{sub 2}O{sub 3} co-doping which improves important device parameters. In detail, it increases the maximum EL power efficiency and EL decay time, it nearly doubles the fraction of excitable Tb{sup 3+} ions, it shifts the region of high EL powermore » efficiencies to higher injection currents, and it reduces the EL quenching over the device lifetime by an approximate factor of two. It is assumed that the presence of Al{sub 2}O{sub 3} interferes the formation of Tb clusters and related defects. Therefore, the system SiO{sub 2}-Tb{sub 2}O{sub 3}-Al{sub 2}O{sub 3} represents a promising alternative for integrated, Si-based light emitters.« less

Room Temperature Electroluminescence from Tensile-Strained Si0.13Ge0.87/Ge Multiple Quantum Wells on a Ge Virtual Substrate

PubMed Central

Lin, Guangyang; Chen, Ningli; Zhang, Lu; Huang, Zhiwei; Huang, Wei; Wang, Jianyuan; Xu, Jianfang; Chen, Songyan; Li, Cheng

2016-01-01

Direct band electroluminescence (EL) from tensile-strained Si0.13Ge0.87/Ge multiple quantum wells (MQWs) on a Ge virtual substrate (VS) at room temperature is reported herein. Due to the competitive result of quantum confinement Stark effect and bandgap narrowing induced by tensile strain in Ge wells, electroluminescence from Γ1-HH1 transition in 12-nm Ge wells was observed at around 1550 nm. As injection current density increases, additional emission shoulders from Γ2-HH2 transition in Ge wells and Ge VS appeared at around 1300–1400 nm and 1600–1700 nm, respectively. The peak energy of EL shifted to the lower energy side superquadratically with an increase of injection current density as a result of the Joule heating effect. During the elevation of environmental temperature, EL intensity increased due to a reduction of energy between L and Γ valleys of Ge. Empirical fitting of the relationship between the integrated intensity of EL (L) and injection current density (J) with L~Jm shows that the m factor increased with injection current density, suggesting higher light emitting efficiency of the diode at larger injection current densities, which can be attributed to larger carrier occupations in the Γ valley and the heavy hole (HH) valance band at higher temperatures. PMID:28773923

Room Temperature Electroluminescence from Tensile-Strained Si0.13Ge0.87/Ge Multiple Quantum Wells on a Ge Virtual Substrate.

PubMed

Lin, Guangyang; Chen, Ningli; Zhang, Lu; Huang, Zhiwei; Huang, Wei; Wang, Jianyuan; Xu, Jianfang; Chen, Songyan; Li, Cheng

2016-09-27

Direct band electroluminescence (EL) from tensile-strained Si 0.13 Ge 0.87 /Ge multiple quantum wells (MQWs) on a Ge virtual substrate (VS) at room temperature is reported herein. Due to the competitive result of quantum confinement Stark effect and bandgap narrowing induced by tensile strain in Ge wells, electroluminescence from Γ1-HH1 transition in 12-nm Ge wells was observed at around 1550 nm. As injection current density increases, additional emission shoulders from Γ2-HH2 transition in Ge wells and Ge VS appeared at around 1300-1400 nm and 1600-1700 nm, respectively. The peak energy of EL shifted to the lower energy side superquadratically with an increase of injection current density as a result of the Joule heating effect. During the elevation of environmental temperature, EL intensity increased due to a reduction of energy between L and Γ valleys of Ge. Empirical fitting of the relationship between the integrated intensity of EL ( L ) and injection current density ( J ) with L ~ J m shows that the m factor increased with injection current density, suggesting higher light emitting efficiency of the diode at larger injection current densities, which can be attributed to larger carrier occupations in the Γ valley and the heavy hole (HH) valance band at higher temperatures.

Schottky barrier height measurements of Cu/Si(001), Ag/Si(001), and Au/Si(001) interfaces utilizing ballistic electron emission microscopy and ballistic hole emission microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balsano, Robert; Matsubayashi, Akitomo; LaBella, Vincent P., E-mail: vlabella@albany.edu

2013-11-15

The Schottky barrier heights of both n and p doped Cu/Si(001), Ag/Si(001), and Au/Si(001) diodes were measured using ballistic electron emission microscopy and ballistic hole emission microscopy (BHEM), respectively. Measurements using both forward and reverse ballistic electron emission microscopy (BEEM) and (BHEM) injection conditions were performed. The Schottky barrier heights were found by fitting to a linearization of the power law form of the Bell-Kaiser BEEM model. The sum of the n-type and p-type barrier heights are in good agreement with the band gap of silicon and independent of the metal utilized. The Schottky barrier heights are found to bemore » below the region of best fit for the power law form of the BK model, demonstrating its region of validity.« less

Highly efficient phosphorescent organic light-emitting diode with a nanometer-thick Ni silicide/polycrystalline p-Si composite anode.

PubMed

Li, Y Z; Wang, Z L; Luo, H; Wang, Y Z; Xu, W J; Ran, G Z; Qin, G G; Zhao, W Q; Liu, H

2010-07-19

A phosphorescent organic light-emitting diode (PhOLED) with a nanometer-thick (approximately 10 nm) Ni silicide/ polycrystalline p-Si composite anode is reported. The structure of the PhOLED is Al mirror/ glass substrate / Si isolation layer / Ni silicide / polycrystalline p-Si/ V(2)O(5)/ NPB/ CBP: (ppy)(2)Ir(acac)/ Bphen/ Bphen: Cs(2)CO(3)/ Sm/ Au/ BCP. In the composite anode, the Ni-induced polycrystalline p-Si layer injects holes into the V(2)O(5)/ NPB, and the Ni silicide layer reduces the sheet resistance of the composite anode and thus the series resistance of the PhOLED. By adopting various measures for specially optimizing the thickness of the Ni layer, which induces Si crystallization and forms a Ni silicide layer of appropriate thickness, the highest external quantum efficiency and power conversion efficiency have been raised to 26% and 11%, respectively.

Single peak parameters technique for simultaneous measurements: Spectrophotometric sequential injection determination of Fe(II) and Fe(III).

PubMed

Kozak, J; Paluch, J; Węgrzecka, A; Kozak, M; Wieczorek, M; Kochana, J; Kościelniak, P

2016-02-01

Spectrophotometric sequential injection system (SI) is proposed to automate the method of simultaneous determination of Fe(II) and Fe(III) on the basis of parameters of a single peak. In the developed SI system, sample and mixture of reagents (1,10-phenanthroline and sulfosalicylic acid) are introduced into a vessel, where in an acid environment (pH≅3) appropriate compounds of Fe(II) and Fe(III) with 1,10-phenanthroline and sulfosalicylic acid are formed, respectively. Then, in turn, air, sample, EDTA and sample again, are introduced into a holding coil. After the flow reversal, a segment of air is removed from the system by an additional valve and as EDTA replaces sulfosalicylic acid forming a more stable colorless compound with Fe(III), a complex signal is registered. Measurements are performed at wavelength 530 nm. The absorbance measured at minimum of the negative peak and the area or the absorbance measured at maximum of the signal can be used as measures corresponding to Fe(II) and Fe(III) concentrations, respectively. The time of the peak registration is about 2 min. Two-component calibration has been applied to analysis. Fe(II) and Fe(III) can be determined within the concentration ranges of 0.04-4.00 and 0.1-5.00 mg L(-1), with precision less than 2.8% and 1.7% (RSD), respectively and accuracy better than 7% (RE). The detection limit is 0.04 and 0.09 mg L(-1) for Fe(II) and Fe(III), respectively. The method was applied to analysis of artesian water samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Validation of single-fluid and two-fluid magnetohydrodynamic models of the helicity injected torus spheromak experiment with the NIMROD code

NASA Astrophysics Data System (ADS)

Akcay, Cihan; Kim, Charlson C.; Victor, Brian S.; Jarboe, Thomas R.

2013-08-01

We present a comparison study of 3-D pressureless resistive MHD (rMHD) and 3-D presureless two-fluid MHD models of the Helicity Injected Torus with Steady Inductive helicity injection (HIT-SI). HIT-SI is a current drive experiment that uses two geometrically asymmetric helicity injectors to generate and sustain toroidal plasmas. The comparable size of the collisionless ion skin depth di to the resistive skin depth predicates the importance of the Hall term for HIT-SI. The simulations are run with NIMROD, an initial-value, 3-D extended MHD code. The modeled plasma density and temperature are assumed uniform and constant. The helicity injectors are modeled as oscillating normal magnetic and parallel electric field boundary conditions. The simulations use parameters that closely match those of the experiment. The simulation output is compared to the formation time, plasma current, and internal and surface magnetic fields. Results of the study indicate 2fl-MHD shows quantitative agreement with the experiment while rMHD only captures the qualitative features. The validity of each model is assessed based on how accurately it reproduces the global quantities as well as the temporal and spatial dependence of the measured magnetic fields. 2fl-MHD produces the current amplification Itor/Iinj and formation time τf demonstrated by HIT-SI with similar internal magnetic fields. rMHD underestimates Itor/Iinj and exhibits much a longer τf. Biorthogonal decomposition (BD), a powerful mathematical tool for reducing large data sets, is employed to quantify how well the simulations reproduce the measured surface magnetic fields without resorting to a probe-by-probe comparison. BD shows that 2fl-MHD captures the dominant surface magnetic structures and the temporal behavior of these features better than rMHD.

Comparison of protective effects of safflor injection and extract of Ginkgo biloba on lung ischemia/reperfusion injury in rabbits.

PubMed

Tian, Xiao-xi; Wang, Bo-liang; Cao, Yi-zhan; Zhong, Yue-xia; Tu, Yan-yang; Xiao, Jian-bo; He, Qian-feng; Zhai, Li-na

2015-03-01

To observe the protective effects of safflor Injection (SI) and extract of Ginkgo biloba (EGB) on lung ischemia-reperfusion injury (LIRI) and investigate its mechanism. In vivo rabbit model of LIRI was reconstructed. Forty rabbits were randomly and equally divided into four groups: sham-operation group (sham group), ischemia-reperfusion group (model group), ischemia-reperfusion plus SI group (safflor group) and ischemia-reperfusion plus EGB injection group (EGB group). Malondialdehyde (MDA) content, superoxide dismutase (SOD) and xanthine oxidase (XO) activity in serum were measured. The wet/dry weight ratio (W/D) of the lung tissue and activity of myeloperoxidase (MPO) were also tested. Ultrastructure change of the lung tissue was observed by the electron microscope. The expression of intercellular adhesion molecule-1 (ICAM-1) was measured by immunohistochemistry (IHC). In the model group, MDA and XO increased and SOD decreased in serum compared with the sham group (P<0.01). The values of W/D, MPO and ICAM-1 of the model group were higher than those of the sham group (P<0.01), but those of the safflor group and EGB group were significantly lower than those of the model group (P<0.01). The IHC demonstrated that ICAM-1 expression in lung tissue of the model group was significantly higher than those of the safflor group (P<0.01). Compared with safflor group, in the EGB group MDA, XO, MPO decreased, SOD and ICAM-1 expression increased (P<0.05), but the change of W/D was not statistically significant (P>0.05). SI and EGB may attenuate LIRI through antioxidation, inhibition of neutrophil aggregation and down-regulation of ICAM-1 expression. But EGB had more effect on the antioxidation, while SI did better on regulating ICAM-1 expression.

Hot Corrosion Test Facility at the NASA Lewis Special Projects Laboratory

NASA Technical Reports Server (NTRS)

Robinson, Raymond C.; Cuy, Michael D.

1994-01-01

The Hot Corrosion Test Facility (HCTF) at the NASA Lewis Special Projects Laboratory (SPL) is a high-velocity, pressurized burner rig currently used to evaluate the environmental durability of advanced ceramic materials such as SiC and Si3N4. The HCTF uses laboratory service air which is preheated, mixed with jet fuel, and ignited to simulate the conditions of a gas turbine engine. Air, fuel, and water systems are computer-controlled to maintain test conditions which include maximum air flows of 250 kg/hr (550 lbm/hr), pressures of 100-600 kPa (1-6 atm), and gas temperatures exceeding 1500 C (2732 F). The HCTF provides a relatively inexpensive, yet sophisticated means for researchers to study the high-temperature oxidation of advanced materials, and the injection of a salt solution provides the added capability of conducting hot corrosion studies.

Broadband and wide-angle light harvesting by ultra-thin silicon solar cells with partially embedded dielectric spheres.

PubMed

Yang, Zhenhai; Shang, Aixue; Qin, Linling; Zhan, Yaohui; Zhang, Cheng; Gao, Pingqi; Ye, Jichun; Li, Xiaofeng

2016-04-01

We propose a design of crystalline silicon thin-film solar cells (c-Si TFSCs, 2 μm-thick) configured with partially embedded dielectric spheres on the light-injecting side. The intrinsic light trapping and photoconversion are simulated by the complete optoelectronic simulation. It shows that the embedding depth of the spheres provides an effective way to modulate and significantly enhance the optical absorption. Compared to the conventional planar and front sphere systems, the optimized partially embedded sphere design enables a broadband, wide-angle, and strong optical absorption and efficient carrier transportation. Optoelectronic simulation predicts that a 2 μm-thick c-Si TFSC with half-embedded spheres shows an increment of more than 10  mA/cm² in short-circuit current density and an enhancement ratio of more than 56% in light-conversion efficiency, compared to the conventional planar counterparts.

New approach for high reliability, low loss splicing between silica and ZBLAN fibers

NASA Astrophysics Data System (ADS)

Carbonnier, Robin; Zheng, Wenxin

2018-02-01

In the past decade, ZBLAN (ZrF4-BaF2-LaF3-NaF) fibers have drawn increasing interest for laser operations at wavelengths where Fused Silica-based (SiO2) fibers do not perform well. One limitation to the expansion of ZBLAN fiber lasers today is the difficulty to efficiently inject and extract light in/from the guiding medium using SiO2 fibers. Although free space and butt coupling have provided acceptable results, consistent and long lasting physical joints between SiO2 and ZBLAN fibers will allow smaller, cheaper, and more robust component manufacturing. While low loss splices have been reported using a traditional splicing approach, the very low mechanical strength of the joint makes it difficult to scale. Difficulties in achieving a strong bond are mainly due to the large difference of transition temperature between ZBLAN and SiO2 fibers ( 260°C vs 1175°C). This paper presents results obtained by using the high thermal expansion coefficient of the ZBLAN fiber to encapsulate a smaller SiO2 fiber. A CO2 laser glass processing system was used to control the expansion and contraction of the ZBLAN material during the splicing process for optimum reliability. This method produced splices between 125μm ZBLAN to 80μm SiO2 fibers with average transmission loss of 0.225dB (measured at 1550nm) and average ultimate tension strength of 121.4gf. The Resulting splices can be durably packaged without excessive care. Other combinations using 125μm SiO2 fibers tapered to 80μm are also discussed.

Renewed Search for FUN (Fractionated and Unidentified Nuclear Effects) in Primitive Chondrites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tollstrup, D L; Wimpenny, J B; Yin, Q -

Ca-Al-rich inclusions (CAIs) found in primitive chondrites record processes and conditions of the earliest solar system as they are the oldest known solid objects formed in the solar system [1,2]. CAIs with fractionation and unidentified nuclear anomalies (FUN CAIs; [3]) are very rare and thusfar found exclusively in CV carbonaceous chondrites (e.g., Allende and Vigarano)[4]. FUN CAIs are characterized by large nucleosynthetic anomalies in several elements (Ca, Ti, Si, Sr, Ba, Nd, and Sm), large mass-dependant isotope fractionation (Mg, Si, and O), and very little initial {sup 26}Al [4,5 and reference therein]. Formation of FUN CAIs by thermal processing ofmore » presolar dust aggregates prior to the injection of {sup 26}Al into the protoplanetary disk has been proposed. More recently [5] proposed that FUN CAIs formed from a protosolar molecular cloud after injection of {sup 26}Al but before {sup 26}Al and {sup 27}Al were completely homogenized. Therefore discovering more FUN CAIs to perform U-Pb and other short-lived chronometric dating will provide key constraints on the age of the solar system, the isotopic composition of the protosolar molecular cloud, the earliest stages of the thermal processing in the solar system and the timing of {sup 26}Al and other short-lived radionuclide injection into the nascent solar system. Most known FUN CAIs were discovered and studied > 30 yr ago, and their isotope ratios determined using thermal ionization mass spectrometry (TIMS). Most of these FUN CAIs were almost or entirely consumed during their respective analyses. [5] recently identified a new FUN CAI (NWA 779 KS-1) based on O and Mg isotope ratios determined by SIMS and MCICPMS, respectively. We have initiated a systematic search for FUN CAIs in primitive chondrites, taking advantage of the large mass-dependant Mg isotope effects known for FUN inclusions with little or no inferred {sup 26}Al. Our strategy is to use newly developed sample cells capable of holding very large slabs of meteorites for laser ablation interfaced with a multicollector inductively coupled plasma mass spectrometry (LA-MC-ICPMS) at UC Davis. Here report the initial findings of our search and describe the instrument setup we use that provides rapid throughput and accurate results.« less

The role of the substrate in Graphene/Silicon photodiodes

NASA Astrophysics Data System (ADS)

Luongo, G.; Giubileo, F.; Iemmo, L.; Di Bartolomeo, A.

2018-01-01

The Graphene/Silicon (Gr/Si) junction can function as a Schottky diode with performances strictly related to the quality of the interface. Here, we focus on the substrate geometry and on its effects on Gr/Si junction physics. We fabricate and study the electrical and optical behaviour of two types of devices: one made of a Gr/Si planar junction, the second realized with graphene on an array of Si nanotips. We show that the Gr/Si flat device exhibits a reverse photocurrent higher than the forward current and achieves a photoresponsivity of 2.5 A/W. The high photoresponse is due to the charges photogenerated in Si below a parasitic graphene/SiO2/Si structure, which are injected into the Gr/Si junction region. The other device with graphene on Si-tips displays a reverse current that grows exponentially with the bias. We explain this behaviour by taking into account the tip geometry of the substrate, which magnifies the electric field and shifts the Fermi level of graphene, thus enabling fine-tuning of the Schottky barrier height. The Gr/Si-tip device achieves a higher photoresponsivity, up to 3 A/W, likely due to photocharge internal multiplication.

Cofilin Knockdown Attenuates Hemorrhagic Brain Injury-induced Oxidative Stress and Microglial Activation in Mice.

PubMed

Alhadidi, Qasim; Nash, Kevin M; Alaqel, Saleh; Sayeed, Muhammad Shahdaat Bin; Shah, Zahoor A

2018-05-08

Intracerebral hemorrhage (ICH) resulting from the rupture of the blood vessels in the brain is associated with significantly higher mortality and morbidity. Clinical studies focused on alleviating the primary injury, hematoma formation and expansion, were largely ineffective, suggesting that secondary injury-induced inflammation and the formation of reactive species also contribute to the overall injury process. In this study, we explored the effects of cofilin knockdown in a mouse model of ICH. Animals given stereotaxic injections of cofilin siRNA, 72-h prior to induction of ICH by collagenase injection within the area of siRNA administration showed significantly decreased cofilin expression levels and lower hemorrhage volume and edema, and the animals performed significantly better in neurobehavioral tasks i.e., rotarod, grip strength and neurologic deficit scores. Cofilin siRNA knocked-down mice had reduced ICH-induced DNA fragmentation, blood-brain barrier disruption and microglial activation, with a concomitant increase in astrocyte activation. Increased expression of pro-survival proteins and decreased markers of oxidative stress were also observed in cofilin siRNA-treated mice possibly due to the reduced levels of cofilin. Our results suggest that cofilin plays a major role in ICH-induced secondary injury, and could become a potential therapeutic target. Copyright © 2018 IBRO. Published by Elsevier Ltd. All rights reserved.

Zwitterionic poly(carboxybetaine)-based cationic liposomes for effective delivery of small interfering RNA therapeutics without accelerated blood clearance phenomenon.

PubMed

Li, Yan; Liu, Ruiyuan; Shi, Yuanjie; Zhang, Zhenzhong; Zhang, Xin

2015-01-01

For efficient delivery of small interfering RNA (siRNA) to the target diseased site in vivo, it is important to design suitable vehicles to control the blood circulation of siRNA. It has been shown that surface modification of cationic liposome/siRNA complexes (lipoplexes) with polyethylene glycol (PEG) could enhance the circulation time of lipoplexes. However, the first injection of PEGylated lipoplexes in vivo induces accelerated blood clearance and enhances hepatic accumulation of the following injected PEGylated lipoplexes, which is known as the accelerated blood clearance (ABC) phenomenon. Herein, we developed zwitterionic poly(carboxybetaine) (PCB) modified lipoplexes for the delivery of siRNA therapeutics, which could avoid protein adsorption and enhance the stability of lipoplexes as that for PEG. Quite different from the PEGylation, the PCBylated lipoplexes could avoid ABC phenomenon, which extended the blood circulation time and enhanced the tumor accumulation of lipoplexes in vivo. After accumulation in tumor site, the PCBylation could promote the cellular uptake and endosomal/lysosomal escape of lipoplexes due to its unique chemical structure and pH-sensitive ability. With excellent tumor accumulation, cellular uptake and endosomal/lysosomal escape abilities, the PCBylated lipoplexes significantly inhibited tumor growth and induced tumor cell apoptosis.

Assessment of drug delivery and anticancer potentials of nanoparticles-loaded siRNA targeting STAT3 in lung cancer, in vitro and in vivo.

PubMed

Das, Jayeeta; Das, Sreemanti; Paul, Avijit; Samadder, Asmita; Bhattacharyya, Soumya Sundar; Khuda-Bukhsh, Anisur Rahman

2014-03-21

Activation of signal transducer and activator of transcription3 (STAT3) is a hallmark of several types of cancer. Failure to inhibit STAT3 expression by injection of siRNA for STAT3 directly to Balb/c mice led us to adopt alternative means. We formulated nanoparticle-based encapsulation of siRNA (NsiRNA) with polyethylenimine (PEI) and poly(lactide-co-glycolide) (PLGA) and characterized them. The siRNA treated and NsiRNA-treated cells were subjected separately to different assay systems. We also checked if NsiRNA could cross the blood brain barrier (BBB). Cell viability reduced dramatically in A549 cells after NsiRNA administration (23.89% at 24 h), thereby implicating considerable silencing of STAT3 by NsiRNA, but not after siRNA administration. Compared to controls, a significant decrease in expression of IL-6 and the angiogenic factor (VEGF) and increase in Caspase 3 activity was observed with corresponding regression in tumor growth in mice treated with NsiRNA. NsiRNA induced apoptosis of cells and arrested cells at G1/G0 stage, both in vitro and in vivo. Apoptosis was also verified by Annexin-V-FITC/Propidium-iodide staining. NsiRNA could cross blood brain barrier. Overall results revealed PEI-PLGA to be a promising carrier for delivery of siRNA targeting STAT3 expression, which can be utilized as an effective strategy for cancer therapy. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Electroluminescence and transport properties in amorphous silicon nanostructures

NASA Astrophysics Data System (ADS)

Irrera, Alessia; Iacona, Fabio; Crupi, Isodiana; Presti, Calogero D.; Franzò, Giorgia; Bongiorno, Corrado; Sanfilippo, Delfo; Di Stefano, Gianfranco; Piana, Angelo; Fallica, Pier Giorgio; Canino, Andrea; Priolo, Francesco

2006-03-01

We report the results of a detailed study on the structural, electrical and optical properties of light emitting devices based on amorphous Si nanostructures. Amorphous nanostructures may constitute an interesting system for the monolithic integration of optical and electrical functions in Si ULSI technology. In fact, they exhibit an intense room temperature electroluminescence (EL), with the advantage of being formed at a temperature of 900 °C, while at least 1100 °C is needed for the formation of Si nanocrystals. Optical and electrical properties of amorphous Si nanocluster devices have been studied in the temperature range between 30 and 300 K. The EL is seen to have a bell-shaped trend as a function of temperature with a maximum at around 60 K. The efficiency of these devices is comparable to that found in devices based on Si nanocrystals, although amorphous nanostructures exhibit peculiar working conditions (very high current densities and low applied voltages). Time resolved EL measurements demonstrate the presence of a short lifetime, only partially due to the occurrence of non-radiative phenomena, since the very small amorphous clusters formed at 900 °C are characterized by a short radiative lifetime. By forcing a current through the device a phenomenon of charge trapping in the Si nanostructures has been observed. Trapped charges affect luminescence through an Auger-type non-radiative recombination of excitons. Indeed, it is shown that unbalanced injection of carriers (electrons versus holes) is one of the main processes limiting luminescence efficiency. These data will be reported and the advantages and limitations of this approach will be discussed.

Analysis of the Electrical Properties of an Electron Injection Layer in Alq3-Based Organic Light Emitting Diodes.

PubMed

Kim, Soonkon; Choi, Pyungho; Kim, Sangsub; Park, Hyoungsun; Baek, Dohyun; Kim, Sangsoo; Choi, Byoungdeog

2016-05-01

We investigated the carrier transfer and luminescence characteristics of organic light emitting diodes (OLEDs) with structure ITO/HAT-CN/NPB/Alq3/Al, ITO/HAT-CN/NPB/Alq3/Liq/Al, and ITO/HAT-CN/NPB/Alq3/LiF/A. The performance of the OLED device is improved by inserting an electron injection layer (EIL), which induces lowering of the electron injection barrier. We also investigated the electrical transport behaviors of p-Si/Alq3/Al, p-Si/Alq3/Liq/Al, and p-Si/Alq3/LiF/Al Schottky diodes, by using current-voltage (L-V) and capacitance-voltage (C-V) characterization methods. The parameters of diode quality factor n and barrier height φ(b) were dependent on the interlayer materials between Alq3 and Al. The barrier heights φ(b) were 0.59, 0.49, and 0.45 eV, respectively, and the diode quality factors n were 1.34, 1.31, and 1.30, respectively, obtained from the I-V characteristics. The built in potentials V(bi) were 0.41, 0.42, and 0.42 eV, respectively, obtained from the C-V characteristics. In this experiment, Liq and LiF thin film layers improved the carrier transport behaviors by increasing electron injection from Al to Alq3, and the LiF schottky diode showed better I-V performance than the Liq schottky diode. We confirmed that a Liq or LiF thin film inter-layer governs electron and hole transport at the Al/Alq3 interface, and has an important role in determining the electrical properties of OLED devices.

Bone repair using a new injectable self-crosslinkable bone substitute.

PubMed

Fellah, Borhane H; Weiss, Pierre; Gauthier, Olivier; Rouillon, Thierry; Pilet, Paul; Daculsi, Guy; Layrolle, Pierre

2006-04-01

A new injectable and self-crosslinkable bone substitute (IBS2) was developed for filling bone defects. The IBS2 consisted of a chemically modified polymer solution mixed with biphasic calcium phosphate (BCP) ceramic particles. The polymer hydroxypropylmethyl cellulose was functionalized with silanol groups (Si-HPMC) and formed a viscous solution (3 wt %) in alkaline medium. With a decrease in pH, self-hardening occurred due to the formation of intermolecular -Si-O- bonds. During setting, BCP particles, 40 to 80 microm in diameter, were added to the polymer solution at a weight ratio of 50/50. The resulting injectable material was bilaterally implanted into critically sized bone defects at the distal femoral epiphyses of nine New Zealand White rabbits. The IBS2 filled the bone defects entirely and remained in place. After 8 weeks, bone had grown centripetally and progressed towards the center of the defects. Newly formed bone, ceramic, and nonmineralized tissue ratios were 24.6% +/- 5.6%, 21.6% +/- 5.8%, and 53.7% +/- 0.1%, respectively. Mineralized and mature bone was observed between and in contact with the BCP particles. The bone/ceramic apposition was 73.4% +/- 10.6%. The yield strength for the IBS2-filled defects was 16.4 +/- 7.2 MPa, significantly higher than for the host trabecular bone tissue (2.7 +/- 0.4 MPa). This study showed that BCP particles supported the bone healing process by osteoconduction while the Si-HPMC hydrogel created intergranular space for bone ingrowth. This new injectable and self-crosslinkable bone substitute could be used conveniently in orthopedic surgery for filling critical-size bone defects. Copyright 2006 Orthopaedic Research Society

Electrically pumped continuous wave quantum dot lasers epitaxially grown on patterned, on-axis (001) Si

DOE Office of Scientific and Technical Information (OSTI.GOV)

Norman, Justin; Kennedy, M. J.; Selvidge, Jennifer

High performance III-V lasers at datacom and telecom wavelengths on on-axis (001) Si are needed for scalable datacenter interconnect technologies. We demonstrate electrically injected quantum dot lasers grown on on-axis (001) Si patterned with {111} v-grooves lying in the [110] direction. No additional Ge buffers or substrate miscut was used. The active region consists of five InAs/InGaAs dot-in-a-well layers. Here, we achieve continuous wave lasing with thresholds as low as 36 mA and operation up to 80°C.

Electrically pumped continuous wave quantum dot lasers epitaxially grown on patterned, on-axis (001) Si

DOE PAGES

Norman, Justin; Kennedy, M. J.; Selvidge, Jennifer; ...

2017-02-14

High performance III-V lasers at datacom and telecom wavelengths on on-axis (001) Si are needed for scalable datacenter interconnect technologies. We demonstrate electrically injected quantum dot lasers grown on on-axis (001) Si patterned with {111} v-grooves lying in the [110] direction. No additional Ge buffers or substrate miscut was used. The active region consists of five InAs/InGaAs dot-in-a-well layers. Here, we achieve continuous wave lasing with thresholds as low as 36 mA and operation up to 80°C.

Vitamin A-coupled liposomes containing siRNA against HSP47 ameliorate skin fibrosis in chronic graft-versus-host disease.

PubMed

Yamakawa, Tomohiro; Ohigashi, Hiroyuki; Hashimoto, Daigo; Hayase, Eiko; Takahashi, Shuichiro; Miyazaki, Miyono; Minomi, Kenjiro; Onozawa, Masahiro; Niitsu, Yoshiro; Teshima, Takanori

2018-03-29

Chronic graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (SCT) is characterized by multiorgan fibrosis and profoundly affects the quality of life of transplant survivors. Heat shock protein 47 (HSP47), a collagen-specific molecular chaperone, plays a critical role in collagen synthesis in myofibroblasts. We explored the role of HSP47 in the fibrotic process of cutaneous chronic GVHD in mice. Immunohistochemical analysis showed massive fibrosis with elevated amounts of collagen deposits and accumulation of F4/80 + macrophages, as well as myofibroblasts expressing HSP47 and retinol-binding protein 1 in the skin after allogeneic SCT. Repeated injection of anti-colony-stimulating factor (CSF-1) receptor-blocking antibodies significantly reduced HSP47 + myofibroblasts in the skin, indicating a macrophage-dependent accumulation of myofibroblasts. Vitamin A-coupled liposomes carrying HSP47 small interfering RNA (siRNA) (VA-lip HSP47) delivered HSP47 siRNA to cells expressing vitamin A receptors and knocked down their HSP47 in vitro. Intravenously injected VA-lip HSP47 were specifically distributed to skin fibrotic lesions and did not affect collagen synthesis in healthy skin. VA-lip HSP47 knocked down HSP47 expression in myofibroblasts and significantly reduced collagen deposition without inducing systemic immunosuppression. It also abrogated fibrosis in the salivary glands. These results highlight a cascade of fibrosis in chronic GVHD; macrophage production of transforming growth factor β mediates fibroblast differentiation to HSP47 + myofibroblasts that produce collagen. VA-lip HSP47 represent a novel strategy to modulate fibrosis in chronic GVHD by targeting HSP47 + myofibroblasts without inducing immunosuppression. © 2018 by The American Society of Hematology.

Transdermal Delivery of siRNA through Microneedle Array

NASA Astrophysics Data System (ADS)

Deng, Yan; Chen, Jiao; Zhao, Yi; Yan, Xiaohui; Zhang, Li; Choy, Kwongwai; Hu, Jun; Sant, Himanshu J.; Gale, Bruce K.; Tang, Tao

2016-02-01

Successful development of siRNA therapies has significant potential for the treatment of skin conditions (alopecia, allergic skin diseases, hyperpigmentation, psoriasis, skin cancer, pachyonychia congenital) caused by aberrant gene expression. Although hypodermic needles can be used to effectively deliver siRNA through the stratum corneum, the major challenge is that this approach is painful and the effects are restricted to the injection site. Microneedle arrays may represent a better way to deliver siRNAs across the stratum corneum. In this study, we evaluated for the first time the ability of the solid silicon microneedle array for punching holes to deliver cholesterol-modified housekeeping gene (Gapdh) siRNA to the mouse ear skin. Treating the ear with microneedles showed permeation of siRNA in the skin and could reduce Gapdh gene expression up to 66% in the skin without accumulation in the major organs. The results showed that microneedle arrays could effectively deliver siRNA to relevant regions of the skin noninvasively.

Sequential injection system for simultaneous determination of sucrose and phosphate in cola drinks using paired emitter-detector diode sensor.

PubMed

Saetear, Phoonthawee; Khamtau, Kittiwut; Ratanawimarnwong, Nuanlaor; Sereenonchai, Kamonthip; Nacapricha, Duangjai

2013-10-15

This work presents the simultaneous determination of sucrose and phosphate by using sequential injection (SI) system with a low cost paired emitter-detector diode (PEDD) light sensor. The PEDD uses two 890 nm LEDs. Measurement of sucrose in Brix unit was carried out based on the detection of light refraction occurring at the liquid interface (the schlieren effect) between the sucrose solution and water. Phosphate was measured from the formation of calcium phosphate with turbidimetric detection. With careful design of the loading sequence and volume (sample--precipitating reagent--sample), simultaneous detection of sucrose and phosphate was accomplished with the single PEDD detector. At the optimized condition, linear calibrations from 1 to 7 Brix sucrose and from 50 to 200mg PO4(3-)L(-1) were obtained. Good precision at lower than 2% RSD (n=10) for both analytes with satisfactory throughput of 21 injections h(-1) was achieved. The method was successfully applied for the determination of sucrose and phosphate in cola drinks. The proposed method is readily applicable for automation and is found to be an alternative method to conventional procedures for on-line quality control process in cola drink industry. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

Wear properties of 10 vol.% silicon carbide particulate-reinforced aluminum composite fabricated by powder injection molding

NASA Astrophysics Data System (ADS)

Patcharawit, T.; Ngeekoh, A.; Chuankrekkul, N.

2017-09-01

Wear properties of aluminum matrix composites reinforced with silicon carbide particulate of 10 vol.% addition was investigated in as-sintered and heat-treated conditions under varying loads at -5, -25, -45 and -65N using a ball on flat type of wear test. The composite was fabricated by powder injection molding and sintering at 650 °C for 3 hours. Solution treatment was carried out at 550 °C for 2 hours followed by age-hardening at 160 °C for 6 hours. SEM and XRD results indicated Al and SiCp are present as matrix and reinforcement, while AlN, Al2Cu and Mg2Si were also detected. Further precipitation of Al2Cu and Mg2Si in heat-treated samples promoted maximum macro and micro Vickers hardness values, which were achieved at 161 and 157 Hv respectively. Wear weight loss increased with increasing minus load level. The coefficient of friction was found in the range of 0.042-0.048. Wear mechanisms were determined as the combination of abrasive, adhesion and oxidation.

Si-based Nanoparticles: a biocompatibility study

NASA Astrophysics Data System (ADS)

Rivolta, I.; Lettiero, B.; Panariti, A.; D'Amato, R.; Maurice, V.; Falconieri, M.; Herlein, N.; Borsella, E.; Miserocchi, G.

2010-10-01

Exposure to silicon nanoparticles (Si-NPs) may occur in professional working conditions or for people undergoing a diagnostic screening test. Despite the fact that silicon is known as a non-toxic material, in the first case the risk is mostly related to the inhalation of nanoparticles, thus the most likely route of entry is across the lung alveolar epithelium. In the case of diagnostic imaging, nanoparticles are usually injected intravenously and Si-NPs could impact on the endothelial wall. In our study we investigated the interaction between selected Si-based NPs and an epithelial lung cell line. Our data showed that, despite the overall silicon biocompatibility, however accurate studies of the potential toxicity induced by the nanostructure and engineered surface characteristics need to be accurately investigated before Si nanoparticles can be safely used for in vivo applications as bio-imaging, cell staining and drug delivery.

Therapeutic effect of photodynamic therapy combined with targeted delivery of silencing vascular endothelial growth factor (Conference Presentation)

NASA Astrophysics Data System (ADS)

Hsu, Yih-Chih

2016-03-01

Photodynamic therapy is a novel therapeutic modality to treat cancer by using a photosensitizer which is activated by a light source to produce reactive oxygen species and mediates tumours oxygen-independent hypoxic conditions. Vascular endothelial growth factor (VEGF) is one of the primary factors that affect tumor angiogenesis. Another emerging treatment to cure cancer is the use of interference RNA to silence a specific mRNA sequence. Such treatment requires a delivery system such as liposomes. The nanoparticle size measured was about 30 nm. Cellular uptake study was performed to verify that the nanoparticles have a sigma receptor mediated pathway. Non-targeted LCP NPs did not show significant difference with or without haloperidol but has a lower intensity as than targeted LCP NPs. These results confirm that LCP NPs have a receptor mediated pathway. Cell viability was found to decrease at 25 nM of transfected VEGF siRNA. Combined therapy of PDT and VEGF siRNA showed significant response as compared with PDT and gene therapy alone. In vivo toxicity assay with mice treated with targeted LCP NPs containing control siRNA or VEGF siRNA and non-targeted LCP NPs containing VEGF siRNA did not show any significant difference with the PBS injected group which suggests that there is no toxicity with the dose. It suggests that PDT combined with targeted gene therapy has a potential mean to achieve better therapeutic outcome.

MHD Simulation of the HIT-SI Experiment

NASA Astrophysics Data System (ADS)

Marklin, George

2003-10-01

The Helicity Injected Torus (HIT) experiment at the University of Washington has been reconfigured into a high beta spheromak with steady state AC current drive [1]. Helicity is injected by two half torus Reversed Field Pinches (RFP's) connected to the ends of the cylindrically symmetric flux conserver, rotated by 90 degrees from each other. The RFP's are driven with sinusoidally varying voltage and flux. Each side has its voltage and flux in phase, but is 90 degrees out of phase from the other side. The helicity injection rate, which is proportional to the voltage times the flux, goes like sin(wt)^2 on one side and cos(wt)^2 on the other, making the total injection rate constant in time. The complex multiply connected 3-dimensional geometry of this device make it difficult to simulate with existing codes that typically use a structured mesh. This poster will describe a new 3D MHD simulation code and a new 3D Taylor state code which both use an unstructured finite element mesh. The mesh is generated from a CAD-like description of an arbitrary arrangement of 3D geometrical objects. Taylor states in the HIT-SI geometry will be shown for different combinations of fluxes in the two injectors. MHD simulation results will be shown starting from a Taylor state with uniform density and temperature and continuing through several cycles of time dependent helicity injection. Field line tracing plots will show the quality of the flux surfaces at various stages in the injection cycle. [1] T. R. Jarboe, Fusion Technology, vol. 36, p. 85, 1999

Targeting Promoter-Associated Noncoding RNA In Vivo.

PubMed

Civenni, Gianluca

2017-01-01

There are many classes of noncoding RNAs (ncRNAs), with wide-ranging functionalities (e.g., RNA editing, mediation of mRNA splicing, ribosomal function). MicroRNAs (miRNAs) and long ncRNAs (lncRNAs) are implicated in a wide variety of cellular processes, including the regulation of gene expression. Incorrect expression or mutation of lncRNAs has been reported to be associated with several disease conditions, such a malignant transformation in humans. Importantly, pivotal players in tumorigenesis and cancer progression, such as c-Myc, may be regulated by lncRNA at promoter level. The function of lncRNA can be reduced with antisense oligonucleotides that sequester or degrade mature lncRNAs. In alternative, lncRNA transcription can be blocked by small interference RNA (RNAi), which had acquired, recently, broad interested in clinical applications. In vivo-jetPEI™ is a linear polyethylenimine mediating nucleic acid (DNA, shRNA, siRNA, oligonucelotides) delivery with high efficiency. Different in vivo delivery routes have been validated: intravenous (IV), intraperitoneal (IP), intratumoral, subcutaneous, topical, and intrathecal. High levels of nucleic acid delivery are achieved into a broad range of tissues, such as lung, salivary glands, heart, spleen, liver, and prostate upon systemic administration. In addition, in vivo-jetPEI™ is also an efficient carrier for local gene and siRNA delivery such as intratumoral or topical application on the skin. After systemic injection, siRNA can be detected and the levels can be validated in target tissues by qRT-PCR. Targeting promoter-associated lncRNAs with siRNAs (small interfering RNAs) in vivo is becoming an exciting breakthrough for the treatment of human disease.

Report of work done for technical assistance agreement 1269 between Sandia National Laboratories and the Watkins-Johnson Company: Chemical reaction mechanisms for computational models of SiO{sub 2} CVD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ho, P.; Johannes, J.; Kudriavtsev, V.

The use of computational modeling to improve equipment and process designs for chemical vapor deposition (CVD) reactors is becoming increasingly common. Commercial codes are available that facilitate the modeling of chemically-reacting flows, but chemical reaction mechanisms must be separately developed for each system of interest. One f the products of the Watkins-Johnson Company (WJ) is a reactor marketed to semiconductor manufacturers for the atmospheric-pressure chemical vapor deposition (APCVD) of silicon oxide films. In this process, TEOS (tetraethoxysilane, Si(OC{sub 2}H{sub 5}){sub 4}) and ozone (O{sub 3}) are injected (in nitrogen and oxygen carrier gases) over hot silicon wafers that are beingmore » carried through the system on a moving belt. As part of their equipment improvement process, WJ is developing computational models of this tool. In this effort, they are collaborating with Sandia National Laboratories (SNL) to draw on Sandia`s experience base in understanding and modeling the chemistry of CVD processes.« less

The role of chemical structure on the magnetic and electronic properties of Co{sub 2}FeAl{sub 0.5}Si{sub 0.5}/Si(111) interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuerbanjiang, Balati; Nedelkoski, Zlatko; Ghasemi, Arsham

2016-04-25

We show that Co{sub 2}FeAl{sub 0.5}Si{sub 0.5} film deposited on Si(111) has a single crystal structure and twin related epitaxial relationship with the substrate. Sub-nanometer electron energy loss spectroscopy shows that in a narrow interface region there is a mutual inter-diffusion dominated by Si and Co. Atomic resolution aberration-corrected scanning transmission electron microscopy reveals that the film has B2 ordering. The film lattice structure is unaltered even at the interface due to the substitutional nature of the intermixing. First-principles calculations performed using structural models based on the aberration corrected electron microscopy show that the increased Si incorporation in the filmmore » leads to a gradual decrease of the magnetic moment as well as significant spin-polarization reduction. These effects can have significant detrimental role on the spin injection from the Co{sub 2}FeAl{sub 0.5}Si{sub 0.5} film into the Si substrate, besides the structural integrity of this junction.« less

Molecule desorption induced by gate-voltage application in MOS structure

NASA Astrophysics Data System (ADS)

Hirota, Nozomu; Hattori, Ken; Daimon, Hiroshi; Hattori, Azusa N.; Tanaka, Hidekazu

2016-04-01

For the first time, we demonstrate desorption from a MOS surface by applying gate voltages (V G). We observed CH4, CO, and CO2 desorption from a MOS (Fe nanofilm/a-SiO2/Si) surface in vacuum only when applying negative V G, suggesting the occurrence of electronic excitation by hot-hole injection. This demonstration is the first step in the application of MOSs to electrically controlled catalysts.

Sildenafil improves blood perfusion in steroid-induced avascular necrosis of femoral head in rabbits via a protein kinase G-dependent mechanism.

PubMed

Song, Qichun; Ni, Jianlong; Jiang, Hongyuan; Shi, Zhibin

2017-10-01

The aim of the study were to evaluate the effect of sildenafil against avascular necrosis of femoral head (ANFH) in a rabbit model, and to study the role of protein kinase G (PKG) pathway and vascular endothelial growth factor (VEGF) in ANFH. Three weeks after inducing ANFH with methylprednisolone injection, 45 female adult New Zealand white rabbits were divided into three groups and treated as follows: group SI received daily intraperitoneal sildenafil with a dose of 10 mg/kg per day; group SD received daily sildenafil identically to group SI plus auricular vein injection DT3 (a specific PKG inhibitor); group NS received only normal saline. The blood perfusion function in the femoral head was measured by perfusion MRI and ink artery infusion. Bilateral femora heads were examined histopathologically for the presence of osteonecrosis; VEGF of tissue was examined by Western blot analysis; cGMP level and PKG activity were also measured. The incidence of ANFH in SI group was significantly lower than that observed in NS and SD groups (p < 0.05). VEGF in SI group was increased compared to NS group. cGMP level and PKG activity were also significantly different between NS and SI group (p < 0.05). However, these effects of sildenafil in SD group were all markedly inhibited by the administration of DT3 compared to SI group. Sildenafil appear to increase the perfusion of femoral head by up-regulating VEGF through PKG pathway. The increased perfusion of femoral head could prevent ANFH. Copyright © 2017 Turkish Association of Orthopaedics and Traumatology. Production and hosting by Elsevier B.V. All rights reserved.

Understanding fuel anti-knock performances in modern SI engines using fundamental HCCI experiments

DOE PAGES

Yang, Yi; Dec, John E.; Sjoberg, Magnus; ...

2015-08-19

Modern spark-ignition (SI) engine technologies have considerably changed in-cylinder conditions under which fuel autoignition and engine knock take place. In this paper, fundamental HCCI engine experiments are proposed as a means for characterizing the impact of these technologies on the knock propensity of different fuels. In particular, the impacts of turbocharging, direct injection (DI), and downspeeding on operation with ethanol and gasoline are investigated to demonstrate this approach. Results reported earlier for ethanol and gasoline on HCCI combustion are revisited with the new perspective of how their autoignition characteristics fit into the anti-knock requirement in modern SI engines. For example,more » the weak sensitivity to pressure boost demonstrated by ethanol in HCCI autoignition can be used to explain the strong knock resistance of ethanol fuels for turbocharged SI engines. Further, ethanol's high sensitivity to charge temperature makes charge cooling, which can be produced by fuel vaporization via direct injection or by piston expansion via spark-timing retard, very effective for inhibiting knock. On the other hand, gasoline autoignition shows a higher sensitivity to pressure, so only very low pressure boost can be applied before knock occurs. Gasoline also demonstrates low temperature sensitivity, so it is unable to make as effective use of the charge cooling produced by fuel vaporization or spark retard. These arguments comprehensively explain literature results on ethanol's substantially better anti-knock performance over gasoline in modern turbocharged DISI engines. Fundamental HCCI experiments such as these can thus be used as a diagnostic and predictive tool for knock-limited SI engine performance for various fuels. As a result, examples are presented where HCCI experiments are used to identify biofuel compounds with good potential for modern SI-engine applications.« less

Synthesis of a colloid solution of silica-coated gold nanoparticles for X-ray imaging applications

NASA Astrophysics Data System (ADS)

Kobayashi, Yoshio; Nagasu, Ryoko; Shibuya, Kyosuke; Nakagawa, Tomohiko; Kubota, Yohsuke; Gonda, Kohsuke; Ohuchi, Noriaki

2014-08-01

This work proposes a method for fabricating silica-coated gold (Au) nanoparticles, surface modified with poly(ethylene glycol) (PEG) (Au/SiO2/PEG), with a particle size of 54.8 nm. X-ray imaging of a mouse is performed with the colloid solution. A colloid solution of 17.9 nm Au nanoparticles was prepared by reducing Au ions (III) with sodium citrate in water at 80 °C. The method used for silica-coating the Au nanoparticles was composed of surface-modification of the Au nanoparticles with (3-aminopropyl)-trimethoxysilane (APMS) and a sol-gel process. The sol-gel process was performed in the presence of the surface-modified Au nanoparticles using tetraethylorthosilicate, APMS, water, and sodium hydroxide, in which the formation of silica shells and the introduction of amino groups to the silica-coated particles took place simultaneously (Au/SiO2-NH2). Surface modification of the Au/SiO2-NH2 particles with PEG, or PEGylation of the particle surface, was performed by adding PEG with a functional group that reacted with an amino group in the Au/SiO2-NH2 particle colloid solution. A computed tomography (CT) value of the aqueous colloid solution of Au/SiO2/PEG particles with an actual Au concentration of 0.112 M was as high as 922 ± 12 Hounsfield units, which was higher than that of a commercial X-ray contrast agent with the same iodine concentration. Injecting the aqueous colloid solution of Au/SiO2/PEG particles into a mouse increased the light contrast of tissues. A CT value of the heart rose immediately after the injection, and this rise was confirmed for up to 6 h.

IRF5 regulates lung macrophages M2 polarization during severe acute pancreatitis in vitro.

PubMed

Sun, Kang; He, Song-Bing; Qu, Jian-Guo; Dang, Sheng-Chun; Chen, Ji-Xiang; Gong, Ai-Hua; Xie, Rong; Zhang, Jian-Xin

2016-11-14

To investigate the role of interferon regulatory factor 5 (IRF5) in reversing polarization of lung macrophages during severe acute pancreatitis (SAP) in vitro . A mouse SAP model was established by intraperitoneal (ip) injections of 20 μg/kg body weight caerulein. Pathological changes in the lung were observed by hematoxylin and eosin staining. Lung macrophages were isolated from bronchoalveolar lavage fluid. The quantity and purity of lung macrophages were detected by fluorescence-activated cell sorting and evaluated by real-time polymerase chain reaction (RT-PCR). They were treated with IL-4/IRF5 specific siRNA (IRF5 siRNA) to reverse their polarization and were evaluated by detecting markers expression of M1/M2 using RT-PCR. SAP associated acute lung injury (ALI) was induced successfully by ip injections of caerulein, which was confirmed by histopathology. Lung macrophages expressed high levels of IRF5 as M1 phenotype during the early acute pancreatitis stages. Reduction of IRF5 expression by IRF5 siRNA reversed the action of macrophages from M1 to M2 phenotype in vitro . The expressions of M1 markers, including IRF5 (S + IRF5 siRNA vs S + PBS, 0.013 ± 0.01 vs 0.054 ± 0.047, P < 0.01), TNF-α (S + IRF5 siRNA vs S + PBS, 0.0003 ± 0.0002 vs 0.019 ± 0.018, P < 0.001), iNOS (S + IRF5 siRNA vs S + PBS, 0.0003 ± 0.0002 vs 0.026 ± 0.018, P < 0.001) and IL-12 (S + IRF5 siRNA vs S + PBS, 0.000005 ± 0.00004 vs 0.024 ± 0.016, P < 0.001), were decreased. In contrast, the expressions of M2 markers, including IL-10 (S + IRF5 siRNA vs S + PBS, 0.060 ± 0.055 vs 0.0230 ± 0.018, P < 0.01) and Arg-1 (S + IRF5 siRNA vs S + PBS, 0.910 ± 0.788 vs 0.0036 ± 0.0025, P < 0.001), were increased. IRF5 siRNA could reverse the lung macrophage polarization more effectively than IL-4. Treatment with IRF5 siRNA can reverse the pancreatitis-induced activation of lung macrophages from M1 phenotype to M2 phenotype in SAP associated with ALI.

Preparation of siRNA encapsulated nanoliposomes suitable for siRNA delivery by simply discontinuous mixing.

PubMed

Mokhtarieh, Amir Abbas; Lee, Jieun; Kim, Semi; Lee, Myung Kyu

2018-06-01

Previously a scalable and extrusion-free method has been developed for efficient liposomal encapsulation of DNA by twice stepwise mixing of lipids in ethanol and DNA solution using T-shape mixing chamber. In this study, we prepared nanoliposomes encapsulating siRNA by simply discontinuous mixing of lipids in ethanol/ether/water mixture and acidic siRNA solution without use of special equipment. The simple mixing siRNA/liposomal particles (siRNA/SMLs) prepared using ethanol/ether/water (3:1:1) mixture showed 120.4 ± 20.2 nm particle size, 0.174 ± 0.033 polydispersity and 86.5 ± 2.76% siRNA encapsulation rate. In addition, the SMLs almost completely protected the encapsulated siRNA from RNase A digestion. Coupling of anti-human epidermal growth factor receptor (EGFR) Fab' to siRNA/SMLs enhanced EGFR-specific cell penetration of SMLs and induced siRNA dependent gene silencing. Unexpectedly, the Cy5.5-labeled Fab' showed almost no in vivo targeting to the xenografted A549 tumors in SCID-NOD mice. However, multiple injection of the unmodified siRNA/SMLs accumulated in the tumors and induced siRNA-dependent in vivo gene silencing. These results demonstrate that the siRNA/SMLs can be used as a siRNA delivery tool for gene therapy. Copyright © 2018 Elsevier B.V. All rights reserved.

Ultrasound-mediated gene delivery of naked plasmid DNA in skeletal muscles: a case for bolus injections.

PubMed

Sanches, Pedro Gomes; Mühlmeister, Mareike; Seip, Ralf; Kaijzel, Eric; Löwik, Clemens; Böhmer, Marcel; Tiemann, Klaus; Grüll, Holger

2014-12-10

Localized gene delivery has many potential clinical applications. However, the nucleic acids (e.g. pDNA and siRNA) are incapable of passively crossing the endothelium, cell membranes and other biological barriers which must be crossed to reach their intracellular targets. A possible solution is the use of ultrasound to burst circulating microbubbles inducing transient permeabilization of surrounding tissues which mediates nucleic acid extravasation and cellular uptake. In this study we report on an optimization of the ultrasound gene delivery technique. Naked pDNA (200 μg) encoding luciferase and SonoVue® microbubbles were co-injected intravenously in mice. The hindlimb skeletal muscles were exposed to ultrasound from a non-focused transducer (1 MHz, 1.25 MPa, PRI 30s) and injection protocols and total amounts as well as ultrasound parameters were systemically varied. Gene expression was quantified relative to a control using a bioluminescence camera system at day 7 after sonication. Bioluminescence ratios in sonicated/control muscles of up to 101× were obtained. In conclusion, we were able to specifically deliver genetic material to the selected skeletal muscles and overall, the use of bolus injections and high microbubble numbers resulted in increased gene expression reflected by stronger bioluminescence signals. Based on our data, bolus injections seem to be required in order to achieve transient highly concentrated levels of nucleic acids and microbubbles at the tissue of interest which upon ultrasound exposure should lead to increased levels of gene delivery. Thus, ultrasound mediated gene delivery is a promising technique for the clinical translation of localized drug delivery. Copyright © 2014 Elsevier B.V. All rights reserved.

The requirement for enhanced CREB1 expression in consolidation of long-term synaptic facilitation and long-term excitability in sensory neurons of Aplysia

PubMed Central

Liu, Rong-Yu; Cleary, Leonard J.; Byrne, John H.

2011-01-01

Accumulating evidence suggests that the transcriptional activator CREB1 is important for serotonin (5-HT)-induced long-term facilitation (LTF) of the sensorimotor synapse in Aplysia. Moreover, creb1 is among the genes activated by CREB1, suggesting a role for this protein beyond the induction phase of LTF. The time course of the requirement for CREB1 synthesis in the consolidation of long-term facilitation was examined using RNA interference (RNAi) techniques in sensorimotor co-cultures. Injection of CREB1 small-interfering RNA (siRNA) immediately or 10 h after 5-HT treatment blocked LTF when measured at 24 h and 48 h after treatment. In contrast, CREB1 siRNA did not block LTF when injected 16 h after 5-HT treatment. These results demonstrate that creb1 expression must be sustained for a relatively long time in order to support the consolidation of LTF. In addition, LTF is also accompanied by a long-term increase in the excitability (LTE) of sensory neurons (SNs). Because LTE was observed in the isolated SN after 5-HT treatment, this long-term change was intrinsic to that element of the circuit. LTE was blocked when CREB1 siRNA was injected into isolated SNs immediately after 5-HT treatment. These data suggest that 5-HT-induced CREB1 synthesis is required for consolidation of both LTF and LTE. PMID:21543617

Flex Fuel Optimized SI and HCCI Engine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Guoming; Schock, Harold; Yang, Xiaojian

The central objective of the proposed work is to demonstrate an HCCI (homogeneous charge compression ignition) capable SI (spark ignited) engine that is capable of fast and smooth mode transition between SI and HCCI combustion modes. The model-based control technique was used to develop and validate the proposed control strategy for the fast and smooth combustion mode transition based upon the developed control-oriented engine; and an HCCI capable SI engine was designed and constructed using production ready two-step valve-train with electrical variable valve timing actuating system. Finally, smooth combustion mode transition was demonstrated on a metal engine within eight enginemore » cycles. The Chrysler turbocharged 2.0L I4 direct injection engine was selected as the base engine for the project and the engine was modified to fit the two-step valve with electrical variable valve timing actuating system. To develop the model-based control strategy for stable HCCI combustion and smooth combustion mode transition between SI and HCCI combustion, a control-oriented real-time engine model was developed and implemented into the MSU HIL (hardware-in-the-loop) simulation environment. The developed model was used to study the engine actuating system requirement for the smooth and fast combustion mode transition and to develop the proposed mode transition control strategy. Finally, a single cylinder optical engine was designed and fabricated for studying the HCCI combustion characteristics. Optical engine combustion tests were conducted in both SI and HCCI combustion modes and the test results were used to calibrate the developed control-oriented engine model. Intensive GT-Power simulations were conducted to determine the optimal valve lift (high and low) and the cam phasing range. Delphi was selected to be the supplier for the two-step valve-train and Denso to be the electrical variable valve timing system supplier. A test bench was constructed to develop control strategies for the electrical variable valve timing (VVT) actuating system and satisfactory electrical VVT responses were obtained. Target engine control system was designed and fabricated at MSU for both single-cylinder optical and multi-cylinder metal engines. Finally, the developed control-oriented engine model was successfully implemented into the HIL simulation environment. The Chrysler 2.0L I4 DI engine was modified to fit the two-step vale with electrical variable valve timing actuating system. A used prototype engine was used as the base engine and the cylinder head was modified for the two-step valve with electrical VVT actuating system. Engine validation tests indicated that cylinder #3 has very high blow-by and it cannot be reduced with new pistons and rings. Due to the time constraint, it was decided to convert the four-cylinder engine into a single cylinder engine by blocking both intake and exhaust ports of the unused cylinders. The model-based combustion mode transition control algorithm was developed in the MSU HIL simulation environment and the Simulink based control strategy was implemented into the target engine controller. With both single-cylinder metal engine and control strategy ready, stable HCCI combustion was achived with COV of 2.1% Motoring tests were conducted to validate the actuator transient operations including valve lift, electrical variable valve timing, electronic throttle, multiple spark and injection controls. After the actuator operations were confirmed, 15-cycle smooth combustion mode transition from SI to HCCI combustion was achieved; and fast 8-cycle smooth combustion mode transition followed. With a fast electrical variable valve timing actuator, the number of engine cycles required for mode transition can be reduced down to five. It was also found that the combustion mode transition is sensitive to the charge air and engine coolant temperatures and regulating the corresponding temperatures to the target levels during the combustion mode transition is the key for a smooth combustion mode transition. As a summary, the proposed combustion mode transition strategy using the hybrid combustion mode that starts with the SI combustion and ends with the HCCI combustion was experimentally validated on a metal engine. The proposed model-based control approach made it possible to complete the SI-HCCI combustion mode transition within eight engine cycles utilizing the well controlled hybrid combustion mode. Without intensive control-oriented engine modeling and HIL simulation study of using the hybrid combustion mode during the mode transition, it would be impossible to validate the proposed combustion mode transition strategy in a very short period.« less

A New Approach for the Treatment of Arthritis in Mice with a Novel Conjugate of an anti-C5aR1 antibody and C5 siRNA

PubMed Central

Mehta, Gaurav; Scheinman, Robert I.; Holers, V. Michael; Banda, Nirmal K.

2015-01-01

Rheumatoid Arthritis (RA) is an inflammatory autoimmune joint disease in which the complement system plays an important role. Of the several components of complement, current evidence points to C5 as the most important inducer of inflammation. Several groups generated antibodies or siRNAs or small molecule inhibitors against C5 and C5aR1 (CD88) which have showed some efficacy in RA in animal models. However, none of these candidate therapeutics has moved from bench to bedside. Here we test in CAIA a new therapeutic strategy using a novel anti-C5ab-C5 siRNA conjugate. We first demonstrate that while C5aR2 or C5L2 (GPR77) plays no role in collagen antibody induced arthritis (CAIA), C5aR1 contributes to pathogenesis. We demonstrate that injection of siRNAs blocking either C5, C5aR1 or the combination decreased clinical disease activity (CDA) in mice with CAIA by 45%, 51% and 58%, respectively. Anti-C5 antibody (BB5.1) has only limited efficacy nonetheless significantly reduced arthritis up to 66%. We then generated a novel anti-C5aR1ab-protamine-C5siRNA conjugate. Here we show for the first time that while unconjugated antibody plus siRNAs reduce arthritis by 19%, our an anti-C5aR1ab - protamine - C5 siRNA conjugate was effective in reducing arthritis by 83% along with a parallel decrease in histopathology, C3 deposition, neutrophils and macrophages in the joints of mice with CAIA. These data suggest that by targeting anti-C5 siRNAs to the receptor for its C5a activation fragment (C5aR1), a striking clinical effect can be realized. PMID:25917104

The rheological behavior of fracture-filling cherts: example of Barite Valley dikes, Barberton Greenstone Belt, South Africa

NASA Astrophysics Data System (ADS)

Ledevin, M.; Arndt, N.; Simionovici, A.

2014-05-01

A 100 m-thick complex of near-vertical carbonaceous chert dikes marks the transition from the Mendon to Mapepe Formations (3260 Ma) in the Barberton Greenstone Belt, South Africa. Fracturing was intense in this area, as shown by the profusion and width of the dikes (ca. 1 m on average) and by the abundance of completely shattered rocks. The dike-and-sill organization of the fracture network and the upward narrowing of some of the large veins indicate that at least part of the fluid originated at depth and migrated upward in this hydrothermal plumbing system. Abundant angular fragments of silicified country rock are suspended and uniformly distributed within the larger dikes. Jigsaw-fit structures and confined bursting textures indicate that hydraulic fracturing was at the origin of the veins. The confinement of the dike system beneath an impact spherule bed suggests that the hydrothermal circulations were triggered by the impact and located at the external margin of a large crater. From the geometry of the dikes and the petrography of the cherts, we infer that the fluid that invaded the fractures was thixotropic. On one hand, the injection of black chert into extremely fine fractures is evidence for low viscosity at the time of injection; on the other hand, the lack of closure of larger veins and the suspension of large fragments in a chert matrix provide evidence of high viscosity soon thereafter. The inference is that the viscosity of the injected fluid increased from low to high as the fluid velocity decreased. Such rheological behavior is characteristic of media composed of solid and colloidal particles suspended in a liquid. The presence of abundant clay-sized, rounded particles of silica, carbonaceous matter and clay minerals, the high proportion of siliceous matrix and the capacity of colloidal silica to form cohesive 3-D networks through gelation, account for the viscosity increase and thixotropic behavior of the fluid that filled the veins. Stirring and shearing of the siliceous mush as it was injected imparted a low viscosity by decreasing internal particle interactions; then, as the flow rate declined, the fluid became highly viscous as the inter-particulate bonds (siloxane bonds, Si-O-Si) were reconstituted. The gelation of the chert was rapid and the structure persisted at low temperature (T < 200 °C) before fractures were sealed and chert indurated.

Method of producing silicon. [gas phase reactor multiple injector liquid feed system

NASA Technical Reports Server (NTRS)

Wolf, C. B.; Meyer, T. N. (Inventor)

1980-01-01

A liquid reactant injector assembly suited for the injection of liquid reactant into a high temperature metal reductant vapor and carrier gas stream for the production of metal is presented. The assembly is especially adapted for the continuous production of high purity silicon by the reduction of SiCl4 with sodium. The assembly includes a refractory-lined, hollow metal shell having ten equally-spaced, concentric, radially directed ports provided in the shell and wall. A hydraulic, atomizing type spray nozzle is mounted in each of the ports recessed from the inner wall surface.

Electrical properties of MOS devices fabricated on the 4H-SiC C-face.

NASA Astrophysics Data System (ADS)

Chen, Zengjun; Ahyi, A. C.; Williams, J. R.

2007-11-01

The electrical characteristics of MOS devices fabricated on the carbon face of 4H-SiC will be described. The C-face has a higher oxidation rate and a higher interface trap density compared to the Si-face. The thermal oxidation rate and the distribution of interface traps under different oxidation conditions will be discussed in this presentation. Sequential post-oxidation anneals in nitric oxide and hydrogen effectively reduces the interface density (Dit) near the conduction band edge. However, deeper in the band gap, the trap density remains higher compared to the Si-face. Time-dependent dielectric breakdown (TDDB) studies have also been performed to investigate oxide reliability on the C-face, and current-voltage measurements show that a low barrier height against carrier injection likely contributes to oxide degradation. Nevertheless, the effective channel mobility and threshold voltage for n-channel C-face lateral MOSFETs compare favorably with similar Si-face devices.

Reducing contralateral SI activity reveals hindlimb receptive fields in the SI forelimb-stump representation of neonatally amputated rats.

PubMed

Pluto, Charles P; Chiaia, Nicolas L; Rhoades, Robert W; Lane, Richard D

2005-09-01

In adult rats that sustained forelimb amputation on the day of birth, >30% of multiunit recording sites in the forelimb-stump representation of primary somatosensory cortex (SI) also respond to cutaneous hindlimb stimulation when cortical GABA(A+B) receptors are blocked (GRB). This study examined whether hindlimb receptive fields could also be revealed in forelimb-stump sites by reducing one known source of excitatory input to SI GABAergic neurons, the contralateral SI cortex. Corpus callosum projection neurons connect homotopic SI regions, making excitatory contacts onto pyramidal cells and interneurons. Thus in addition to providing monosynaptic excitation in SI, callosal fibers can produce disynaptic inhibition through excitatory synapses with inhibitory interneurons. Based on the latter of these connections, we hypothesized that inactivating the contralateral (intact) SI forelimb region would "unmask" normally suppressed hindlimb responses by reducing the activity of SI GABAergic neurons. The SI forelimb-stump representation was first mapped under normal conditions and then during GRB to identify stump/hindlimb responsive sites. After GRB had dissipated, the contralateral (intact) SI forelimb region was mapped and reversibly inactivated with injections of 4% lidocaine, and selected forelimb-stump sites were retested. Contralateral SI inactivation revealed hindlimb responses in approximately 60% of sites that were stump/hindlimb responsive during GRB. These findings indicate that activity in the contralateral SI contributes to the suppression of reorganized hindlimb receptive fields in neonatally amputated rats.

Development of a solar-powered infrared injection laser microminiature transmitting system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Falter, D.D.; Alley, G.T.; Falter, K.G.

1989-01-01

A solar-powered infrared microminiature transmitting system is being developed to provide scientists with a tool to continuously track and study Africanized bees. Present tracking methods have limited ranges and lack the capability of continuously tracking individual insects. Preliminary field tests of a stationary prototypic transmitter have demonstrated a range of 1.1 km. The basic design consists of an array of nine 1-mm{sup 2} solar cells, which collect energy for storage in a 1.0-{mu}F tantalum chip capacitor. When the capacitor has been charged to a sufficient level, the circuitry that monitors the capacitor voltage level wakes up'' and fires a 5-{mu}smore » pulse through an 840-nm GaAlAs injection laser diode. The process is then repeated, making the signal frequency (which ranges from 50 to 300 Hz) dependent on solar luminance. The solar cells, capacitor, and laser diode are mounted in hybrid microcircuit fashion directly on the silicon substrate containing the CMOS control and driver circuitry. The transmitter measures {approximately}4 {times} 6 mm and weighs {approximately}65 mg. The receiving system is based on an 8-in. telescope and a Si PIN diode detector. 8 refs., 10 figs.« less

Infrared charge-injection-device array performance at low background

NASA Technical Reports Server (NTRS)

Mccreight, C. R.; Goebel, J. H.

1981-01-01

Low-background tests of a 1 x 32 Si:Bi charge-injection-device (CID) IR detector are carried out to evaluate its feasibility for space-based astronomical observations. Optimum performance is obtained at a temperature of 11 K. The sensitivity is found to compare well with that of discrete extrinsic silicon photoconductors. The measured sensitivity and the apparent absence of anomalous effects make extrinsic silicon CID arrays very promising for astronomical applications.

Progress in net shape fabrication of alpha SiC turbine components

NASA Technical Reports Server (NTRS)

Storm, R. S.; Naum, R. G.

1983-01-01

The development status of component technology in an automotive gas turbine Ceramic Applications in Turbine Engines program is discussed, with attention to such materials and processes having a low cost, net shape fabrication potential as sintered alpha-SiC that has been fashioned by means of injection molding, slip casting, and isostatic pressing. The gas turbine elements produced include a gasifier turbine rotor, a turbine wheel, a connecting duct, a combustor baffle, and a transition duct.

NIMROD simulations of HIT-SI plasmas

NASA Astrophysics Data System (ADS)

Akcay, Cihan; Jarboe, Thomas; Nelson, Brian; Kim, Charlson

2011-10-01

HIT-SI (Steady Inductive Helicity Injected Torus) is a current drive experiment that uses two semi-toroidal helicity injectors driven at 5-15 kHz to generate steady inductive helicity injection (SIHI). All the plasma-facing walls of the experiment are coated with an insulating material to guarantee an inductive discharge. NIMROD is a 3-D extended MHD code that can only model toroidally-uniform geometries. The helicity injectors of the experiment are simulated as flux and voltage boundary conditions with odd toroidal symmetry. A highly resistive, thin edge-layer approximates the insulating walls. The simulations are initial-value calculations that use a zero β resistive MHD (rMHD) model with uniform density. The Prandtl number (Pr = 10), and Lundquist number (S = 5 - 50) closely match the experimental values. rMHD calculations at S ~ 10 show no growth of an n = 0 mode and only a few kA of toroidal current whereas HIT-SI has demonstrated toroidal currents greater than 50 kA with a current amplification of 3. At higher S (>= 20) the simulations exhibit significant n = 0 magnetic energy growth and a current amplification exceeding unity: Itor/Iinj >= 1 . While HIT-SI has shown evidence for separatrix formation, rMHD calculations indicate an entirely stochastic magnetic structure during sustainment. Results will also presented for Hall MHD, anticipated to play a crucial role in the physics of SIHI.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Bao; Liu, Wen-Jun; Wei, Lei

Excellent voltage linearity of metal-insulator-metal (MIM) capacitors is highly required for next generation radio frequency integration circuits. In this work, employing atomic layer deposition technique, we demonstrated how the voltage linearity of MIM capacitors was modulated by adding different thickness of SiO{sub 2} layer to the nano-stack of Al{sub 2}O{sub 3}/ZrO{sub 2}. It was found that the quadratic voltage coefficient of capacitance (α) can be effectively reduced from 1279 to −75 ppm/V{sup 2} with increasing the thickness of SiO{sub 2} from zero to 4 nm, which is more powerful than increasing the thickness of ZrO{sub 2} in the Al{sub 2}O{sub 3}/ZrO{sub 2}more » stack. This is attributed to counteraction between the positive α for Al{sub 2}O{sub 3}/ZrO{sub 2} and the negative one for SiO{sub 2} in the MIM capacitors with Al{sub 2}O{sub 3}/ZrO{sub 2}/SiO{sub 2} stacks. Interestingly, voltage-polarity dependent conduction behaviors in the MIM capacitors were observed. For electron bottom-injection, the addition of SiO{sub 2} obviously suppressed the leakage current; however, it abnormally increased the leakage current for electron top-injection. These are ascribed to the co-existence of shallow and deep traps in ZrO{sub 2}, and the former is in favor of the field-assisted tunnelling conduction and the latter contributes to the trap-assisted tunnelling process. The above findings will be beneficial to device design and process optimization for high performance MIM capacitors.« less

Production of al-si alloy feedstocks using the solvent hot mixing method

NASA Astrophysics Data System (ADS)

Ni, J. Q.; Han, K. Q.; Yu, M. H.

2018-05-01

Powder injection molding is a promising low-cost technique for net shape processing of metal and ceramic components. This study aimed to investigate a new method for preparing aluminium (Al) – silicon (Si) alloy feedstock using the solvent hot mixing process. For this purpose, micron-sized Al-Si (20 wt. %) alloy powder was mixed with a binder consisting of 55 wt. % carnauba wax, 45 wt. % high-density polyethylene, and 3 wt. % stearic acid in a hot xylene bath. The scanning electron microscopy technique, thermogravimetric analysis, density measurement and torque measurements were used to verify the homogeneity of the feedstock. Moreover, the feedstock was chosen to perform the molding, debinding cycle and sintering. An Al-Si (20 wt. %) alloy part was successfully produced using this new method.

Tunable sustained intravitreal drug delivery system for daunorubicin using oxidized porous silicon

PubMed Central

Hou, Huiyuan; Nieto, Alejandra; Ma, Feiyan; Freeman, William R.; Sailor, Michael J.; Cheng, Lingyun

2014-01-01

Daunorubicin (DNR) is an effective inhibitor of an array of proteins involved in neovascularization, including VEGF and PDGF. These growth factors are directly related to retina scar formation in many devastating retinal diseases. Due to the short vitreous half-life and narrow therapeutic window, ocular application of DNR is limited. It has been shown that a porous silicon (pSi) based delivery system can extend DNR vitreous residence from a few days to 3 months. In this study we investigated the feasibility of altering the pore size of the silicon particles to regulate the payload release. Modulation of the etching parameters allowed control of the nano-pore size from 15 nm to 95 nm. In vitro studies showed that degradation of pSi O2 increased with increasing pore size and the degradation of pSi O2 was approximately constant for a given particle type. The degradation of pSi O2 with 43 nm pores was significantly greater than the other two particles with smaller pores, judged by observed and normalized mean Si concentration of the dissolution samples (44.2±8.9 vs 25.7±5.6 or 21.2±4.2 µg/mL, p<0.0001). In vitro dynamic DNR release revealed that pSiO2-CO2H:DNR (Porous silicon dioxide with covalent loading of daunorubicin) with large pores (43 nm) yielded a significantly higher DNR level than particles with 15 or 26 nm pores (13.5±6.9 ng/mL vs. 2.3±1.6 ng/mL and 1.1±0.9 ng/mL, p<0.0001). After two months of in vitro dynamic release, 54% of the pSiO2-CO2H:DNR particles still remained in the dissolution chamber by weight. In vivo drug release study demonstrated that free DNR in vitreous at post-injection day 14 was 66.52 ng/mL for 95 nm pore size pSiO2-CO2H:DNR, 10.76 ng/mL for 43 nm pSi O2-CO2 H:DNR, and only 1.05 ng/mL for 15 nm pSi O2-CO2 H:DNR. Pore expansion from 15 nm to 95 nm led to a 63 folds increase of DNR release (p<0.0001) and a direct correlation between the pore size and the drug levels in the living eye vitreous was confirmed. The present study demonstrates the feasibility of regulating DNR release from pSi O2 covalently loaded with DNR by engineering the nano-pore size of pSi. PMID:24424270

The Commercialization of the SiC Flame Sensor

NASA Astrophysics Data System (ADS)

Fedison, Jeffrey B.

2002-03-01

The technical and scientific steps required to produce large quantities of SiC flame sensors is described. The technical challenges required to understand, fabricate, test and package SiC photodiodes in 1990 were numerous since SiC device know how was embryonic. A sense of urgency for a timely replacement of the Geiger Muller gas discharge tube soon entered the scene. New dual fuel GE Power Systems gas turbines, which were designed to lean burn either natural gas or oil for low NOx emissions required a much higher sensitivity sensor. Joint work between GE CRD and Cree Research sponsored by the GE Aircraft Engine Division developed the know how for the fabrication of high sensitivity, high yield, reliable SiC photodiodes. Yield issues were uncovered and overcome. The urgency for system insertion required that SiC diode and sensor circuitry development needed to be carried out simultaneously with power plant field tests of laboratory or prototype sensor assemblies. The sensor and reliability specifications were stringent since the sensors installed on power plant turbine combustor walls are subjected to high levels of vibration, elevated temperatures, and high pressures. Furthermore a fast recovery time was required to sense flame out in spite of the fact that the amplifier circuit needed have high gain and high dynamic range. SiC diode technical difficulties were encountered and overcome. The science of hydrocarbon flames will also be described together with the fortunate overlap of the strong OH emission band with the SiC photodiode sensitivity versus wavelength characteristic. The extremely low dark current (<1pA/cm^2) afforded by the wide band gap and the 3eV sensitivity cutoff at 400nm made if possible to produce low amplifier offsets, high sensitivity and high dynamic range along with immunity to black body radiation from combustor walls. Field tests at power plants that had experienced turbine tripping, whenever oil fuel and/or oil with steam injection for power augmentation, were extremely encouraging. This warrantee problem previously due to the low sensitivity of the Geiger Muller tube was solved using the much higher sensitivity SiC detector. This sensitivity increase is partially due to the fact that the SiC photodiode “sees” the strong OH emission band whereas the Geiger Muller tube can only respond to the shorter wavelength CO emission band. Other successful field tests were observed and acclaimed by power plant operators, which for the first time could track mode switching and power level (flame intensity) because of the high dynamic range (>5000:1). The demand for this product thereupon rose dramatically. This success, the first for SiC devices other than that of SiC blue LEDs, is leading GE to implement this technology in other application fields.

Tunable sustained intravitreal drug delivery system for daunorubicin using oxidized porous silicon.

PubMed

Hou, Huiyuan; Nieto, Alejandra; Ma, Feiyan; Freeman, William R; Sailor, Michael J; Cheng, Lingyun

2014-03-28

Daunorubicin (DNR) is an effective inhibitor of an array of proteins involved in neovascularization, including VEGF and PDGF. These growth factors are directly related to retina scar formation in many devastating retinal diseases. Due to the short vitreous half-life and narrow therapeutic window, ocular application of DNR is limited. It has been shown that a porous silicon (pSi) based delivery system can extend DNR vitreous residence from a few days to 3months. In this study we investigated the feasibility of altering the pore size of the silicon particles to regulate the payload release. Modulation of the etching parameters allowed control of the nano-pore size from 15nm to 95nm. In vitro studies showed that degradation of pSiO2 increased with increasing pore size and the degradation of pSiO2 was approximately constant for a given particle type. The degradation of pSiO2 with 43nm pores was significantly greater than the other two particles with smaller pores, judged by observed and normalized mean Si concentration of the dissolution samples (44.2±8.9 vs 25.7±5.6 or 21.2±4.2μg/mL, p<0.0001). In vitro dynamic DNR release revealed that pSiO2-CO2H:DNR (porous silicon dioxide with covalent loading of daunorubicin) with large pores (43nm) yielded a significantly higher DNR level than particles with 15 or 26nm pores (13.5±6.9ng/mL vs. 2.3±1.6ng/mL and 1.1±0.9ng/mL, p<0.0001). After two months of in vitro dynamic release, 54% of the pSiO2-CO2H:DNR particles still remained in the dissolution chamber by weight. In vivo drug release study demonstrated that free DNR in the vitreous at post-injection day 14 was 66.52ng/mL for 95nm pore size pSiO2-CO2H:DNR, 10.76ng/mL for 43nm pSiO2-CO2H:DNR, and only 1.05ng/mL for 15nm pSiO2-CO2H:DNR. Pore expansion from 15nm to 95nm led to a 63 fold increase of DNR release (p<0.0001) and a direct correlation between the pore size and the drug levels in the living eye vitreous was confirmed. The present study demonstrates the feasibility of regulating DNR release from pSiO2 covalently loaded with DNR by engineering the nano-pore size of pSi. Copyright © 2014 Elsevier B.V. All rights reserved.

Comparative study of neurologic effects of nano-TiO2 versus SiO2 after direct intracerebral exposure in mice

NASA Astrophysics Data System (ADS)

Balvay, A.; Thieriet, N.; Lakhdar, L.; Bencsik, A.

2013-04-01

Titanium and silicon dioxide nanoparticles (TiO2 and SiO2 NPs) are now in daily use in many commercial products of which food, sunscreens, toothpastes or cosmetics. However, their effects on human body, especially on the central nervous system, are still unclear. The aim of this study was to determine whether direct exposition of the brain to TiO2 and SiO2 NPs results in alternations in nervous system function. C57Bl6 mice were exposed to 5 and 10 μg doses of TiO2 and SiO2 NPs through intracerebroventricular administration using a stereotaxic approach. Then the neurologic effects were investigated using motor performance parameters, measured on a rotarod at 20 rpm or at an accelerating rod (from 4 to 40 rpm). Before and after injection, motor activity is registered individually for each mouse exposed, once a week, for 8 weeks. Besides, a group of 3 mice is culled at 1, 2, 3, 4 and 8 weeks after exposure in order to study the time dependant effect on the histopathology of the brain (gliosis, inflammatory process...). Both rotarod tests (accelerating and at 20 rpm) showed that TiO2 and SiO2 NPs exposure could significantly impair the motor performances, even several weeks after initial acute exposure. The first examination of the brain histopathology revealed microglial activation. As it appeared to grow throughout the brain in a time dependant manner this suggests the induction of a long lasting neuroinflammation. These primary findings indicated that exposure to TiO2 and SiO2 NPs could possibly impair the locomotor ability and this deficit may be possibly attributed at least to an inflammatory process maintained till 8 weeks after exposure in the mouse brain. To fully investigate the neurotoxicological consequences of TiO2 and SiO2 NPs exposure, brain contents in these NPs will be also investigated as well as other alterations like neurotransmitter levels. These preliminary data already underline the necessity of more in vivo studies to better characterize TiO2 and SiO2 NPs exposure effects especially on human brain for long-term and low-dose treatment.

A high-fat, high-protein diet attenuates the negative impact of casein-induced chronic inflammation on testicular steroidogenesis and sperm parameters in adult mice.

PubMed

Zhao, Jing-Lu; Zhao, Yu-Yun; Zhu, Wei-Jie

2017-10-01

The interaction between obesity and chronic inflammation has been studied. Diet-induced obesity or chronic inflammation could reduce the testicular functions of males. However, the mechanism underlying the reproductive effects of fattening foods in males with or without chronic inflammation still needs further discussion. This study was aimed to investigate the effects of high-fat, high-protein diet on testicular steroidogenesis and sperm parameters in adult mice under physiological and chronic inflammatory conditions. Because casein can trigger a non-infectious systemic inflammatory response, we used casein injection to induce chronic inflammation in male adult Kunming mice. Twenty-four mice were randomly and equally divided into four groups: (i) normal diet+saline (Control); (ii) normal diet+casein (ND+CS); (iii) high-fat, high-protein diet+saline (HFPD+SI); (iv) high-fat, high-protein diet+casein (HFPD+CS). After 8weeks, there was a significant increase in body weight for groups HFPD+SI and HFPD+CS and a decrease in group ND+CS compared with the control. The serum levels of tumor necrosis factor alpha (TNF-α), interleukin-10 (IL-10) and lipid profiles were increased markedly in groups ND+CS, HFPD+SI and HFPD+CS compared with the control. A remarkable reduction of serum adiponectin level occurred in group HFPD+CS compared with group ND+CS. Sperm parameters (sperm count, viability and abnormality) were also adversely affected in groups ND+CS and HFPD+SI. Groups ND+CS and HFPD+SI showed severe pathological changes in testicular tissues. Semiquantitative RT-PCR, Western blot and immunohistochemical staining also showed significant reductions in both testicular mRNA and protein levels of steroidogenic acute regulatory (StAR) and cytochrome P450scc (CYP11A1) in groups HFPD+SI and HFPD+CS compared with the control, whereas testicular mRNA and protein levels of 3β-hydroxysteroid dehydrogenase (3β-HSD) in groups HFPD+SI and HFPD+CS significantly increased. The mRNA and protein levels of the StAR and 3β-HSD in group HFPD+CS were both higher than those of in group ND+CS. These results indicated that Kunming male mice with high-fat, high-protein diet and casein injection for 8weeks can be used to establish a diet-induced obesity and chronic systemic inflammation. The sperm parameters in groups ND+CS and HFPD+SI decreased accompanied by pathological changes of testicular tissue. This resultant effect of reduced serum testosterone levels was associated with the overproduction of TNF-α and IL-10 and down-regulation of StAR and CYP11A1. Under the same casein-induced chronic inflammation condition, the mice with high-fat, high-protein diet had better testicular steroidogenesis activity and sperm parameters compared with the mice in normal diet, indicating that the mice with casein-induced inflammatory injury consuming a high-fat, high-protein diet gained weight normally, reduced serum adiponectin level and increased testosterone production by an upregulation of 3β-HSD expression. High-fat, high-protein diet attenuated the negative impact of casein-induced chronic inflammation on testicular steroidogenesis and sperm parameters. Copyright © 2017 Elsevier Inc. All rights reserved.

Magnetic resonance imaging of the pancreas in streptozotocin-induced diabetic rats: Gadofluorine P and Gd-DOTA.

PubMed

Cho, Hye Rim; Lee, Youkyung; Doble, Philip; Bishop, David; Hare, Dominic; Kim, Young-Jae; Kim, Kwang Gi; Jung, Hye Seung; Park, Kyong Soo; Choi, Seung Hong; Moon, Woo Kyung

2015-05-21

To investigate the performance of Gadofluorine P-enhanced magnetic resonance imaging (MRI) on the diagnosis of diabetes in a streptozotocin (STZ) -induced diabetic rat model. Fischer 344 rats were treated with STZ. Rats not treated with STZ served as controls. T1-weighted MRI was performed using a 3T scanner before and after the injection of Gd-DOTA or Gadofluorine P (6 diabetic rats, 5 controls). The normalized signal intensity (SI) and the enhancement ratio (ER) of the pancreas were measured at each time point, and the values were compared between the normal and diabetic rats using the Mann-Whitney test. In addition, the values were correlated with the mean islet number. Optimal cut-off values were calculated using a positive test based on receiver operating characteristics. Intrapancreatic Gd concentration after the injection of each contrast media was measured using laser ablation-inductively coupled plasma-mass spectrometry in a separate set of rats (4 diabetic rats, 4 controls for Gadofluorine P; 2, 2 for Gd-DOTA). The normalized SI and ER of the pancreas using Gd-DOTA were not significantly different between diabetic rats and controls. With Gadofluorine P, the values were significantly higher in the diabetic rats than in the control rats 30 min after injection (P < 0.05). The area under the receiver operating characteristic curve that differentiated diabetic rats from the control group was greater for Gadofluorine P than for Gd-DOTA (0.967 vs 0.667, P = 0.085). An increase in normalized SI 30 min after Gadofluorine P was correlated with a decrease in the mean number of islets (r (2) = 0.510, P = 0.014). Intra-pancreatic Gd was higher in rats with Gadofluorine P injection than Gd-DOTA injection (Gadofluorine P vs Gd-DOTA, 7.37 vs 0.00, P < 0.01). A significant difference in the concentration of intrapancreatic Gd was observed between the control and diabetic animals that were sacrificed 30 min after Gadofluorine P injection (control vs diabetic, 3.25 ng/g vs 10.55 ng/g, P < 0.05) CONCLUSION: In this STZ-induced diabetes rat model, Gadofluorine P-enhanced MRI of the pancreas showed high accuracy in the diagnosis of diabetes.

Case series of ultrasound-guided platelet-rich plasma injections for sacroiliac joint dysfunction.

PubMed

Ko, Gordon D; Mindra, Sean; Lawson, Gordon E; Whitmore, Scott; Arseneau, Leigh

2017-01-01

Two-thirds of adults worldwide will experience low back pain at some point in their life. In the following case series, we present four patients with sacroiliac (SI) joint instability and severe chronic low back pain, which was refractory to other treatment modalities. We investigated the efficacy of platelet-rich plasma (PRP) injections, a novel orthobiologic therapy, for reducing SI joint pain, improving quality of life, and maintaining a clinical effect. Short-form McGill Pain Questionnaire (SFM), Numeric Rating Scale (NRS), and Oswestry Low Back Pain and Disability Index were used for evaluation of treatment at pretreatment, 12-months and 48-months after treatment. At follow-up 12-months post-treatment, pooled data from all patients reported a marked improvement in joint stability, a statistically significant reduction in pain, and improvement in quality of life. The clinical benefits of PRP were still significant at 4-years post-treatment. Platelet-rich plasma therapy exhibits clinical usefulness in both pain reduction and for functional improvement in patients with chronic SI joint pain. The improvement in joint stability and low back pain was maintained at 1- and 4-years post-treatment.

A charge inverter for III-nitride light-emitting diodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Zi-Hui, E-mail: zh.zhang@hebut.edu.cn, E-mail: wbi@hebut.edu.cn, E-mail: volkan@stanfordalumni.org, E-mail: sunxw@sustc.edu.cn; Zhang, Yonghui; Bi, Wengang, E-mail: zh.zhang@hebut.edu.cn, E-mail: wbi@hebut.edu.cn, E-mail: volkan@stanfordalumni.org, E-mail: sunxw@sustc.edu.cn

In this work, we propose a charge inverter that substantially increases the hole injection efficiency for InGaN/GaN light-emitting diodes (LEDs). The charge inverter consists of a metal/electrode, an insulator, and a semiconductor, making an Electrode-Insulator-Semiconductor (EIS) structure, which is formed by depositing an extremely thin SiO{sub 2} insulator layer on the p{sup +}-GaN surface of a LED structure before growing the p-electrode. When the LED is forward-biased, a weak inversion layer can be obtained at the interface between the p{sup +}-GaN and SiO{sub 2} insulator. The weak inversion region can shorten the carrier tunnel distance. Meanwhile, the smaller dielectric constantmore » of the thin SiO{sub 2} layer increases the local electric field within the tunnel region, and this is effective in promoting the hole transport from the p-electrode into the p{sup +}-GaN layer. Due to the improved hole injection, the external quantum efficiency is increased by 20% at 20 mA for the 350 × 350 μm{sup 2} LED chip. Thus, the proposed EIS holds great promise for high efficiency LEDs.« less

Effect of the chamber wall on fluorocarbon-assisted atomic layer etching of SiO2 using cyclic Ar/C4F8 plasma

PubMed Central

Kawakami, Masatoshi; Metzler, Dominik; Li, Chen; Oehrlein, Gottlieb S.

2016-01-01

The authors studied the effect of the temperature and chemical state of the chamber wall on process performance for atomic layer etching of SiO2 using a steady-state Ar plasma, periodic injection of a defined number of C4F8 molecules, and synchronized plasma-based Ar+ ion bombardment. To evaluate these effects, the authors measured the quartz coupling window temperature. The plasma gas phase chemistry was characterized using optical emission spectroscopy. It was found that although the thickness of the polymer film deposited in each cycle is constant, the etching behavior changed, which is likely related to a change in the plasma gas phase chemistry. The authors found that the main gas phase changes occur after C4F8 injection. The C4F8 and the quartz window react and generate SiF and CO. The emission intensity changes with wall surface state and temperature. Therefore, changes in the plasma gas species generation can lead to a shift in etching performance during processing. During initial cycles, minimal etching is observed, while etching gradually increases with cycle number. PMID:27375342

Three-dimensional culture and differentiation of human osteogenic cells in an injectable hydroxypropylmethylcellulose hydrogel.

PubMed

Trojani, Christophe; Weiss, Pierre; Michiels, Jean-François; Vinatier, Claire; Guicheux, Jérôme; Daculsi, Guy; Gaudray, Patrick; Carle, Georges F; Rochet, Nathalie

2005-09-01

The present work evaluates a newly developed silated hydroxypropylmethylcellulose (Si-HPMC)-based hydrogel as a scaffold for 3D culture of osteogenic cells. The pH variation at room temperature catalyzes the reticulation and self-hardening of the viscous polymer solution into a gelatine state. We designed reticulation time, final consistency and pH in order to obtain an easy handling matrice, suitable for in vitro culture and in vivo injection. Three human osteogenic cell lines and normal human osteogenic (HOST) cells were cultured in 3D inside this Si-HPMC hydrogel. We show here that osteosarcoma cells proliferate as clonogenic spheroids and that HOST colonies survive for at least 3 weeks. Mineralization assay and gene expression analysis of osteoblastic markers and cytokines, indicate that all the cells cultured in 3D into this hydrogel, exhibited a more mature differentiation status than cells cultured in monolayer on plastic. This study demonstrates that this Si-HPMC hydrogel is well suited to support osteoblastic survival, proliferation and differentiation when used as a new scaffold for 3D culture and represents also a potential basis for an innovative bone repair material.

The potential of silica encapsulated DNA magnetite microparticles (SiDNAMag) for multi-tracer studies in subsurface hydrology

NASA Astrophysics Data System (ADS)

Willem Foppen, Jan; Bogaard, Thom; van Osnabrugge, Bart; Puddu, Michela; Grass, Robert

2015-04-01

With tracer experiments, knowledge on solute transport, travel times, flow pathways, source areas, and linkages between infiltration and exfiltration zones in subsurface hydrological studies can be obtained. To overcome the well-known limitations of artificial tracers, we report here the development and application of an inexpensive method to produce large quantities of environmentally friendly 150-200 nm microparticles composed of a magnetite core to which small fragments of synthetic 80 nt ssDNA were adsorbed, which were then covered by a layer of inert silica (acronym: SiDNAMag). The main advantages of using DNA are the theoretically unlimited amount of different DNA tracers and the low DNA detection limit using the quantitative polymerase chain reaction (qPCR); the main advantage of the silica layer is to prevent DNA decay, while the magnetite core facilitates magnetic separation, recovery and up-concentration. In 10 cm columns of saturated quartz sand, we first injected NaCl, a conservative salt tracer, and measured the breakthrough. Then, we injected SiDNAMag suspended in water of known composition, harvested the SiDNAMag in column effluent samples, and measured the DNA concentration via qPCR after dissolving the SiDNAMag. The results indicated that the timing of the rising limb of the DNA breakthrough curve, the plateau phase and the falling limb were identical to the NaCl breakthrough curve. However, the relative maximum DNA concentration reached during the plateau phase was around 0.3, indicating that around 70% of the SiDNAMag mass was retained in the column. From these results we inferred that SiDNAMag was not retarded and therefore not subject to equilibrium sorption. Instead, first order irreversible kinetic attachment appeared to be the dominant retention mechanism. Based on our results, we speculate that, despite significant retention, due to the low DNA detection limit and the possibility of magnetic up-concentration, the use of SiDNAMag is a very promising technique to determine complex flow patterns, travel times, and flow pathways in many different subsurface hydrological applications.

Multifuntional Nanotherapeutics for the Combinatorial Drug and Gene Therapy in the Treatment of Glioblastoma Multiforme

NASA Astrophysics Data System (ADS)

Hourigan, Breanne

Glioblastoma multiforme (GBM), a grade IV glioma, is the most common primary brain tumor, affecting about 3 out of 100,000 persons per year in the United States. GBM accounts for about 80% of primary malignant brain tumors, and is also the most aggressive of malignant brain tumors. With exhaustive treatment, survival only averages between 12 and 15 months, with a 2-year survival rate less than 25%. New therapeutic strategies are necessary to improve the outcomes of this disease. Chemotherapy with temozolomide (TMZ), a DNA alkylating agent, is used as a first-line of treatment for GBM. However, GBM tumors develop resistance to TMZ over time due to increased expression of O6-methylguanine-DNA methyltransferase (MGMT), a gene responsible for DNA repair. We previously developed cationic, amphiphilic copolymer poly(lactide-co-glycolide)-g-polyethylenimine (PgP) and demonstrated its utility for nucleic acid delivery. Here, we examine the ability of PgP polyplexes to overcome TMZ resistance and improve therapeutic efficacy through combination drug and gene therapy for GBM treatment. In this study, we evaluated the ability of PgP to deliver siRNA targeting to MGMT (siMGMT), a gene responsible for drug resistance in GBM. Our results demonstrated that PgP effectively forms stable complex with siRNA and protects siRNAs from heparin competition assay, serum- and ribonuclease-mediated degradation, confirming the potential of the polyplex for in vivo delivery. Results from MTT assays showed that PgP/siRNA polyplexes exhibited minimal cytotoxicity compared to untreated cells when incubated with T98G human GBM cells. We also demonstrated that PgP/siMGMT polyplexes mediate knockdown of MGMT protein as well as a significant ˜56% and ˜68% knockdown of MGMT mRNA in T98G GBM cells compared to cells treated with PgP complexed with non-targeting siRNA (siNT) at a 60:1 and 80:1 nitrogen:phosphate (N:P) ratio, respectively. Further, co-incubation of PgP/siMGMT polyplexes with TMZ enhanced therapeutic efficacy in T98G GBM cells compared to treatment with the polyplex or TMZ alone. After generation of athymic mouse GBM model, PgP/siMGMT polyplexes were locally injected into the tumor. Relative to untreated injury only, PgP/siMGMT polyplexes significantly reduced MGMT mRNA and protein expression at 3 days post-injection. These studies demonstrate that PgP is an efficient non-viral delivery carrier for therapeutic siMGMT to the tumor cells and may be a promising platform for the combinatorial siRNA/drug therapy for GBM treatment. In the future, we will study the therapeutic efficacy of combination of PgP/siMGMT and TMZ in athymic mouse GBM model.

Fabrication of low reflective nanopore-type black Si layer using one-step Ni-assisted chemical etching for Si solar cell application

NASA Astrophysics Data System (ADS)

Takaloo, AshkanVakilipour; Kolahdouz, Mohammadreza; Poursafar, Jafar; Es, Firat; Turan, Rasit; Ki-Joo, Seung

2018-03-01

Nanotextured Si fabricated through metal-assisted chemical etching (MACE) technique exhibits a promising potential for producing antireflective layer for photovoltaic (PV) application. In this study, a novel single-step nickel (Ni) assisted etching technique was applied to produce an antireflective, nonporous Si (black Si) in an aqueous solution containing hydrofluoric acid (HF), hydrogen peroxide (H2O2) and NiSO4 at 40 °C. Field emission scanning electron microscope was used to characterize different morphologies of the textured Si. Optical reflection measurements of samples were carried out to compare the reflectivity of different morphologies. Results indicated that vertical as well as horizontal pores with nanosized diameters were bored in the Si wafer after 1 h treatment in the etching solution containing different molar ratios of H2O2 to HF. Increasing H2O2 concentration in electrochemical etching solution had a considerable influence on the morphology due to higher injection of positive charges from Ni atoms onto the Si surface. Optimized concentration of H2O2 led to formation of an antireflective layer with 2.1% reflectance of incident light.

Microstructure and Mechanical Properties of Cr-SiC Particles-Reinforced Fe-Based Alloy Coating

NASA Astrophysics Data System (ADS)

Wang, Fu-cheng; Du, Xiao-dong; Zhan, Ma-ji; Lang, Jing-wei; Zhou, Dan; Liu, Guang-fu; Shen, Jian

2015-12-01

In this study, SiC particles were first coated with Cr to form a layer that can protect the SiC particles from dissolution in the molten pool. Then, the Cr-SiC powder was injected into the tail of molten pool during plasma-transferred arc welding process (PTAW), where the temperature was relatively low, to prepare Cr-SiC particles reinforced Fe-based alloy coating. The microstructure and phase composition of the powder and surface coatings were analyzed, and the element distribution and hardness at the interfacial region were also evaluated. The protective layer consists of Cr3Si, Cr7C3, and Cr23C6, which play an important role in the microstructure and mechanical properties. The protective layer is dissolved in the molten pool forming a flocculent region and a transition region between the SiC particles and the matrix. The tribological performance of the coating was also assessed using a ring-block sliding wear tester with GGr15 grinding ring under 490 and 980 N load. Cr-SiC particles-reinforced coating has a lower wear rate than the unreinforced coating.

Injection doping of ultrathin microcrystalline silicon films prepared by CC-CVD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koynov, S.; Grebner, S.; Schwarz, R.

1997-07-01

Recently, the authors have proposed a cyclic method, referred to as Closed Chamber CVD (CC-CVD), for the preparation of {micro}c-Si films of high crystalline fraction at increased deposition rates. In this work, they first report new process conditions of CC-CVD, which result in growth of highly crystalline films with a sharp interface on a foreign substrate. Then these conditions are further used together with a pulsed injection of B{sub 2}H{sub 6} in an appropriate moment of each cycle, so that the disturbance of the crystallization process is prevented. A series of ultrathin {micro}c-Si films, doped by this technique, is characterizedmore » by conductivity measurements, SEM, Raman Scattering, optical transmission and UV reflection. A strong reduction of the transient interface layer is achieved and conductivity as high as 2 S/cm with an activation energy of 27 meV is reached.« less

Plasma-Chemical Synthesis of Oxide Powders Using Transformer-Coupled Discharge

NASA Astrophysics Data System (ADS)

M. Ulanov, I.; V. Isupov, M.; Yu Litvinsev, A.; A. Mischenko, P.

2013-04-01

An experimental investigation of transformer-coupled discharge in an Ar-O2 mixture with the addition of SiCl4, TiCl4 and ZrCl4 has been carried out under the atmospheric pressure of plasma-forming gases. Discharge power and discharge heat losses have been determined, and the dispersion and phase composition of reaction products (oxide powders) has been analyzed with SEM and X-ray diffraction analysis. Investigations reveal the formation of ultrafine oxide powders in the case of vaporized chloride (SiCl4 and TiCl4) injecting into the transformer coupled discharge. In the case of fine powder (ZrCl4) injection, full oxidation was not observed and reaction products consisted of a mixture of ZrO2 and ZrOCl2. A conclusion has been made regarding the perspectives of using transformer-coupled discharge to produce ultrafine oxide powders.

Heat-sink free CW operation of injection microdisk lasers grown on Si substrate with emission wavelength beyond 1.3  μm.

PubMed

Kryzhanovskaya, Natalia; Moiseev, Eduard; Polubavkina, Yulia; Maximov, Mikhail; Kulagina, Marina; Troshkov, Sergey; Zadiranov, Yury; Guseva, Yulia; Lipovskii, Andrey; Tang, Mingchu; Liao, Mengya; Wu, Jiang; Chen, Siming; Liu, Huiyun; Zhukov, Alexey

2017-09-01

High-performance injection microdisk (MD) lasers grown on Si substrate are demonstrated for the first time, to the best of our knowledge. Continuous-wave (CW) lasing in microlasers with diameters from 14 to 30 μm is achieved at room temperature. The minimal threshold current density of 600  A/cm 2 (room temperature, CW regime, heatsink-free uncooled operation) is comparable to that of high-quality MD lasers on GaAs substrates. Microlasers on silicon emit in the wavelength range of 1320-1350 nm via the ground state transition of InAs/InGaAs/GaAs quantum dots. The high stability of the lasing wavelength (dλ/dI=0.1  nm/mA) and the low specific thermal resistance of 4×10 -3 °C×cm 2 /W are demonstrated.

Preclinical Mammalian Safety Studies of EPHARNA (DOPC Nanoliposomal EphA2-Targeted siRNA).

PubMed

Wagner, Michael J; Mitra, Rahul; McArthur, Mark J; Baze, Wallace; Barnhart, Kirstin; Wu, Sherry Y; Rodriguez-Aguayo, Cristian; Zhang, Xinna; Coleman, Robert L; Lopez-Berestein, Gabriel; Sood, Anil K

2017-06-01

To address the need for efficient and biocompatible delivery systems for systemic siRNA delivery, we developed 1,2-Dioleoyl-sn-Glycero-3-Phosphatidylcholine (DOPC) nanoliposomal EphA2-targeted therapeutic (EPHARNA). Here, we performed safety studies of EPHARNA in murine and primate models. Single dosing of EPHARNA was tested at 5 concentrations in mice ( N = 15 per group) and groups were sacrificed on days 1, 14, and 28 for evaluation of clinical pathology and organ toxicity. Multiple dosing of EPHARNA was tested in mice and Rhesus macaques twice weekly at two dose levels in each model. Possible effects on hematologic parameters, serum chemistry, coagulation, and organ toxicity were assessed. Following single-dose EPHARNA administration to mice, no gross pathologic or dose-related microscopic findings were observed in either the acute (24 hours) or recovery (14 and 28 days) phases. The no-observed-adverse-effect level (NOAEL) for EPHARNA is considered >225 μg/kg when administered as a single injection intravenously in CD-1 mice. With twice weekly injection, EPHARNA appeared to stimulate a mild to moderate inflammatory response in a dose-related fashion. There appeared to be a mild hemolytic reaction in the female mice. In Rhesus macaques, minimal to moderate infiltration of mononuclear cells was found in some organs including the gastrointestinal tract, heart, and kidney. No differences attributed to EPHARNA were observed. These results demonstrate that EPHARNA is well tolerated at all doses tested. These data, combined with previously published in vivo validation studies, have led to an ongoing first-in-human phase I clinical trial (NCT01591356). Mol Cancer Ther; 16(6); 1114-23. ©2017 AACR . ©2017 American Association for Cancer Research.

Ion Beam Processing of Diamond

DTIC Science & Technology

1990-05-07

Diamond structure. We can make ohmic contacts to silicon . If we could tailor the structure from Si to Si. C,-, to diamond, we should be able to form a low...func- ricr injection. Refractory metals such as tantalum. tung- tion of contact spacing. Extrapolation of the data to zero sten , or titanium have also...layer of the diamond could be miade n-type gallium nitride. and silicon carbide.- Mater. Sci. Fng.. vol. 91, pp.77-104.1(998. with a five to six orders

Validation of single-fluid and two-fluid magnetohydrodynamic models of the helicity injected torus spheromak experiment with the NIMROD code

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akcay, Cihan; Victor, Brian S.; Jarboe, Thomas R.

We present a comparison study of 3-D pressureless resistive MHD (rMHD) and 3-D presureless two-fluid MHD models of the Helicity Injected Torus with Steady Inductive helicity injection (HIT-SI). HIT-SI is a current drive experiment that uses two geometrically asymmetric helicity injectors to generate and sustain toroidal plasmas. The comparable size of the collisionless ion skin depth d{sub i} to the resistive skin depth predicates the importance of the Hall term for HIT-SI. The simulations are run with NIMROD, an initial-value, 3-D extended MHD code. The modeled plasma density and temperature are assumed uniform and constant. The helicity injectors are modeledmore » as oscillating normal magnetic and parallel electric field boundary conditions. The simulations use parameters that closely match those of the experiment. The simulation output is compared to the formation time, plasma current, and internal and surface magnetic fields. Results of the study indicate 2fl-MHD shows quantitative agreement with the experiment while rMHD only captures the qualitative features. The validity of each model is assessed based on how accurately it reproduces the global quantities as well as the temporal and spatial dependence of the measured magnetic fields. 2fl-MHD produces the current amplification (I{sub tor}/I{sub inj}) and formation time τ{sub f} demonstrated by HIT-SI with similar internal magnetic fields. rMHD underestimates (I{sub tor}/I{sub inj}) and exhibits much a longer τ{sub f}. Biorthogonal decomposition (BD), a powerful mathematical tool for reducing large data sets, is employed to quantify how well the simulations reproduce the measured surface magnetic fields without resorting to a probe-by-probe comparison. BD shows that 2fl-MHD captures the dominant surface magnetic structures and the temporal behavior of these features better than rMHD.« less

siRNA Delivery to the Glomerular Mesangium Using Polycationic Cyclodextrin Nanoparticles Containing siRNA

PubMed Central

Gale, Aaron; Wu, Peiwen; Ma, Rong; Davis, Mark E.

2015-01-01

There is an urgent need for new therapies that can halt or reverse the course of chronic kidney disease with minimal side-effect burden on the patient. Small interfering RNA (siRNA) nanoparticles are new therapeutic entities in clinical development that could be useful for chronic kidney disease treatment because they combine the tissue-specific targeting properties of nanoparticles with the gene-specific silencing effects of siRNA. Recent reports have emerged demonstrating that the kidney, specifically the glomerulus, is a readily accessible site for nanoparticle targeting. Here, we explore the hypothesis that intravenously administered polycationic cyclodextrin nanoparticles containing siRNA (siRNA/CDP-NPs) can be used for delivery of siRNA to the glomerular mesangium. We demonstrate that siRNA/CDP-NPs localize to the glomerular mesangium with limited deposition in other areas of the kidney after intravenous injection. Additionally, we report that both mouse and human mesangial cells rapidly internalize siRNA/CDP-NPs in vitro and that nanoparticle uptake can be enhanced by attaching the targeting ligands mannose or transferrin to the nanoparticle surface. Lastly, we show knockdown of mesangial enhanced green fluorescent protein expression in a reporter mouse strain following iv treatment with siRNA/CDP-NPs. Altogether, these data demonstrate the feasibility of mesangial targeting using intravenously administered siRNA/CDP-NPs. PMID:25734248

Engineering analysis of shortfall for new technologies. Analysis memorandum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1981-03-11

The engineering principles that govern the mpg performance of alternative technologies on the EPA test procedure and under in-use conditions are examined. The results can be used to interpret the shortfall of alternative technologies derived from statistical analyses. The analysis examines each of the four technologies in comparison to the conventional technology counterpart. Manual transmissions are compared to automatics, fuel injected S.I. engines to carburetted S.I. engines, front-wheel drive vehicles to rear-wheel drive vehicles and diesel engines to carburetted S.I. engines. The changes in shortfall of the four technologies in comparison to conventional technologies are explained through differences in responsesmore » to the factors.« less

Excess-Si related defect centers in buried SiO2 thin films

NASA Astrophysics Data System (ADS)

Warren, W. L.; Fleetwood, D. M.; Shaneyfelt, M. R.; Schwank, J. R.; Winokur, P. S.; Devine, R. A. B.

1993-06-01

Using electron paramagnetic resonance (EPR) and capacitance-voltage measurements we have investigated the role of excess-silicon related defect centers as charge traps in separation by the implantation of oxygen materials. Three types of EPR-active centers were investigated: oxygen vacancy Eγ' centers (O3≡Si• +Si≡O3), delocalized Eδ' centers, and D centers (Si3≡Si•). It was found that all of these paramagnetic centers are created by selective hole injection, and are reasonably ascribed as positively charged when paramagnetic. These results provide the first experimental evidence for (1) the charge state of the Eδ' center, and (2) that the D center is an electrically active point defect in these materials.

Defect Generation for a Hydrated Layer and Thermal Stability Based on Ba0.7Sr0.3TiO3/SiO2 as H+ Sensitive Layer in Ion-Sensitive Field-Effect Transistor Devices

NASA Astrophysics Data System (ADS)

Chen, Chun-Yuan; Chou, Jung-Chuan; Chou, Hsueh-Tao

2009-04-01

In this paper, we present a novel sensitive ion-sensitive field-effect transistor (ISFET) membrane based on Ba0.7Sr0.3TiO3 (BST)/SiO2 fabricated by sputtering deposition. The proposed device exhibits a linear shift in acidic solutions in the pH range from 1 to 10. The device sensitivity was about 50-55 mV/pH for different deposition times. We also examined the trapping behavior of the surface hydrated layer using the metal-insulator-semiconductor (MIS) structure. Results show that the hydration layer gives rise to stress polarity dependence of electron injection when immersed in pH buffer solutions. Injection from the gate electrode produces larger positive charges and interface state densities in contrast to the substrate injection, which causes simultaneous positive and negative charge trapping. A physical model that quantitatively describes the asymmetry associated with the hydrated diffusion layer is presented, and the temperature effects of BST/SiO2 ISFET devices in the range from 25 to 65 °C were examined. We observed that pH sensitivity increases with increasing temperature. The temperature coefficient of sensitivity (TCS) can be divided into two different ranges: 0.08 mV/pH °C between 25 and 45 °C, and 0.57 mV/pH °C between 45 and 65 °C. A better thermal stability is produced in the 25 and 45 °C range in comparison with other sensitive layers.

Charge retention in scaled SONOS nonvolatile semiconductor memory devices—Modeling and characterization

NASA Astrophysics Data System (ADS)

Hu, Yin; White, Marvin H.

1993-10-01

A new analytical model is developed to investigate the influence of the charge loss processes in the retention mode of the SONOS NVSM device. The model considers charge loss by the following processes: (1) electron back-tunneling from the nitride traps to the Si conduction band, (2) electron back-tunneling from the nitride traps to the Si/SiO 2 interface traps and (3) hole injection from the Si valence band to the nitride traps. An amphoteric trap charge distribution is used in this model. The new charge retention model predicts that process (1) determines the short term retention, while processes (2) and (3) determine the long term retention. Good agreement has been reached between the results of analytical calculations and the experimental retention data on both surface channel and buried channel SONOS devices.

Balancing cationic and hydrophobic content of PEGylated siRNA polyplexes enhances endosome escape, stability, blood circulation time, and bioactivity in vivo.

PubMed

Nelson, Christopher E; Kintzing, James R; Hanna, Ann; Shannon, Joshua M; Gupta, Mukesh K; Duvall, Craig L

2013-10-22

A family of pH-responsive diblock polymers composed of poly[(ethylene glycol)-b-[(2-(dimethylamino)ethyl methacrylate)-co-(butyl methacrylate)], PEG-(DMAEMA-co-BMA), was reversible addition-fragmentation chain transfer (RAFT) synthesized with 0-75 mol % BMA in the second polymer block. The relative mole % of DMAEMA and BMA was varied in order to identify a polymer that can be used to formulate PEGylated, siRNA-loaded polyplex nanoparticles (NPs) with an optimized balance of cationic and hydrophobic content in the NP core based on siRNA packaging, cytocompatibility, blood circulation half-life, endosomal escape, and in vivo bioactivity. The polymer with 50:50 mol % of DMAEMA:BMA (polymer "50 B") in the RAFT-polymerized block efficiently condensed siRNA into 100 nm NPs that displayed pH-dependent membrane disruptive behavior finely tuned for endosomal escape. In vitro delivery of siRNA with polymer 50 B produced up to 94% protein-level knockdown of the model gene luciferase. The PEG corona of the NPs blocked nonspecific interactions with constituents of human whole blood, and the relative hydrophobicity of polymer 50 B increased NP stability in the presence of human serum or the polyanion heparin. When injected intravenously, 50 B NPs enhanced blood circulation half-life 3-fold relative to more standard PEG-DMAEMA (0 B) NPs (p < 0.05), due to improved stability and a reduced rate of renal clearance. The 50 B NPs enhanced siRNA biodistribution to the liver and other organs and significantly increased gene silencing in the liver, kidneys, and spleen relative to the benchmark polymer 0 B (p < 0.05). These collective findings validate the functional significance of tuning the balance of cationic and hydrophobic content of polyplex NPs utilized for systemic siRNA delivery in vivo.

IRF5 regulates lung macrophages M2 polarization during severe acute pancreatitis in vitro

PubMed Central

Sun, Kang; He, Song-Bing; Qu, Jian-Guo; Dang, Sheng-Chun; Chen, Ji-Xiang; Gong, Ai-Hua; Xie, Rong; Zhang, Jian-Xin

2016-01-01

AIM To investigate the role of interferon regulatory factor 5 (IRF5) in reversing polarization of lung macrophages during severe acute pancreatitis (SAP) in vitro. METHODS A mouse SAP model was established by intraperitoneal (ip) injections of 20 μg/kg body weight caerulein. Pathological changes in the lung were observed by hematoxylin and eosin staining. Lung macrophages were isolated from bronchoalveolar lavage fluid. The quantity and purity of lung macrophages were detected by fluorescence-activated cell sorting and evaluated by real-time polymerase chain reaction (RT-PCR). They were treated with IL-4/IRF5 specific siRNA (IRF5 siRNA) to reverse their polarization and were evaluated by detecting markers expression of M1/M2 using RT-PCR. RESULTS SAP associated acute lung injury (ALI) was induced successfully by ip injections of caerulein, which was confirmed by histopathology. Lung macrophages expressed high levels of IRF5 as M1 phenotype during the early acute pancreatitis stages. Reduction of IRF5 expression by IRF5 siRNA reversed the action of macrophages from M1 to M2 phenotype in vitro. The expressions of M1 markers, including IRF5 (S + IRF5 siRNA vs S + PBS, 0.013 ± 0.01 vs 0.054 ± 0.047, P < 0.01), TNF-α (S + IRF5 siRNA vs S + PBS, 0.0003 ± 0.0002 vs 0.019 ± 0.018, P < 0.001), iNOS (S + IRF5 siRNA vs S + PBS, 0.0003 ± 0.0002 vs 0.026 ± 0.018, P < 0.001) and IL-12 (S + IRF5 siRNA vs S + PBS, 0.000005 ± 0.00004 vs 0.024 ± 0.016, P < 0.001), were decreased. In contrast, the expressions of M2 markers, including IL-10 (S + IRF5 siRNA vs S + PBS, 0.060 ± 0.055 vs 0.0230 ± 0.018, P < 0.01) and Arg-1 (S + IRF5 siRNA vs S + PBS, 0.910 ± 0.788 vs 0.0036 ± 0.0025, P < 0.001), were increased. IRF5 siRNA could reverse the lung macrophage polarization more effectively than IL-4. CONCLUSION Treatment with IRF5 siRNA can reverse the pancreatitis-induced activation of lung macrophages from M1 phenotype to M2 phenotype in SAP associated with ALI. PMID:27895424

Anisotropic Janus Si nanopillar arrays as a microfluidic one-way valve for gas-liquid separation

NASA Astrophysics Data System (ADS)

Wang, Tieqiang; Chen, Hongxu; Liu, Kun; Li, Yang; Xue, Peihong; Yu, Ye; Wang, Shuli; Zhang, Junhu; Kumacheva, Eugenia; Yang, Bai

2014-03-01

In this paper, we demonstrate a facile strategy for the fabrication of a one-way valve for microfluidic (MF) systems. The micro-valve was fabricated by embedding arrays of Janus Si elliptical pillars (Si-EPAs) with anisotropic wettability into a MF channel fabricated in poly(dimethylsiloxane) (PDMS). Two sides of the Janus pillar are functionalized with molecules with distinct surface energies. The ability of the Janus pillar array to act as a valve was proved by investigating the flow behaviour of water in a T-shaped microchannel at different flow rates and pressures. In addition, the one-way valve was used to achieve gas-liquid separation. We believe that the Janus Si-EPAs modified by specific surface functionalization provide a new strategy to control the flow and motion of fluids in MF channels.In this paper, we demonstrate a facile strategy for the fabrication of a one-way valve for microfluidic (MF) systems. The micro-valve was fabricated by embedding arrays of Janus Si elliptical pillars (Si-EPAs) with anisotropic wettability into a MF channel fabricated in poly(dimethylsiloxane) (PDMS). Two sides of the Janus pillar are functionalized with molecules with distinct surface energies. The ability of the Janus pillar array to act as a valve was proved by investigating the flow behaviour of water in a T-shaped microchannel at different flow rates and pressures. In addition, the one-way valve was used to achieve gas-liquid separation. We believe that the Janus Si-EPAs modified by specific surface functionalization provide a new strategy to control the flow and motion of fluids in MF channels. Electronic supplementary information (ESI) available: The XPS spectrum of the as-prepared Janus arrays after the MHA modification; the SEM images of the PFS-MHA Janus Si pillar arrays fabricated through oblique evaporation of gold along the short axis of the elliptical pillars; images of the cross-shaped MF channel and Rhodamine aqueous solution injecting in a cross-shaped MF channel taken at different times; the plot data of DPFS/DMHA against the flow rate of the aqueous solution; the plot data of failure pressure against the bottom size of the channel; optical microscopy images of the Janus pillar array with less density of pillars; optical microscopy images of the T junction with higher magnification; the video of Rhodamine solution running in the T-shaped microchannel integrated with the Janus Si-EPAs; the video of the entire gas-liquid separation process. See DOI: 10.1039/c3nr05865d

Light-Emitting Diodes Based on Colloidal Silicon Quantum Dots with Octyl and Phenylpropyl Ligands.

PubMed

Liu, Xiangkai; Zhao, Shuangyi; Gu, Wei; Zhang, Yuting; Qiao, Xvsheng; Ni, Zhenyi; Pi, Xiaodong; Yang, Deren

2018-02-14

Colloidal silicon quantum dots (Si QDs) hold ever-growing promise for the development of novel optoelectronic devices such as light-emitting diodes (LEDs). Although it has been proposed that ligands at the surface of colloidal Si QDs may significantly impact the performance of LEDs based on colloidal Si QDs, little systematic work has been carried out to compare the performance of LEDs that are fabricated using colloidal Si QDs with different ligands. Here, colloidal Si QDs with rather short octyl ligands (Octyl-Si QDs) and phenylpropyl ligands (PhPr-Si QDs) are employed for the fabrication of LEDs. It is found that the optical power density of PhPr-Si QD LEDs is larger than that of Octyl-Si QD LEDs. This is due to the fact that the surface of PhPr-Si QDs is more oxidized and less defective than that of Octyl-Si QDs. Moreover, the benzene rings of phenylpropyl ligands significantly enhance the electron transport of QD LEDs. It is interesting that the external quantum efficiency (EQE) of PhPr-Si QD LEDs is lower than that of Octyl-Si QD LEDs because the benzene rings of phenylpropyl ligands suppress the hole transport of QD LEDs. The unbalance between the electron and hole injection in PhPr-Si QD LEDs is more serious than that in Octyl-Si QD LEDs. The currently obtained highest optical power density of ∼0.64 mW/cm 2 from PhPr-Si QD LEDs and highest EQE of ∼6.2% from Octyl-Si QD LEDs should encourage efforts to further advance the development of high-performance optoelectronic devices based on colloidal Si QDs.

Characterizing and Exploring the Formation Mechanism of Salt Deposition by Reusing Advanced-softened, Silica-rich, Oilfield-produced Water (ASOW) in Superheated Steam Pipeline

PubMed Central

Dong, Bin; Xu, Ying; Lin, Senmin; Dai, Xiaohu

2015-01-01

To dispose of large volumes of oilfield-produced water, an environmentally friendly method that reuses advanced-softened, silica-rich, oilfield-produced water (ASOW) as feedwater was implemented via a 10-month pilot-scale test in oilfield. However, salt deposition detrimental to the efficiency and security of steam injection system was generated in superheated steam pipeline. To evaluate the method, the characteristics and formation mechanism of the deposition were explored. The silicon content and total hardness of the ASOW were 272.20 mg/L and 0.018 mg/L, respectively. Morphology and composition of the deposition were determined by scanning electron microscope–energy dispersive spectrometry (SEM-EDS), inductively coupled plasma–mass spectroscopy (ICP-MS), X-ray diffraction (XRD), laser Raman spectroscopy (LRS) and X-ray photoelectron spectroscopy (XPS). Na2Si2O5, Na2CO3 and trace silanes were identified in the deposition. In addition, the solubility of the deposition was about 99%, suggesting that it is very different from traditional scaling. The results of a simulation experiment and thermal analysis system (TGA and TG-FTIR) proved that Na2CO3 and Si(OH)4 (gas) are involved in the formation of Na2Si2O5, which is ascribed mainly to the temperature difference between the superheated steam and the pipe wall. These findings provide an important reference for improving the reuse of ASOW and reducing its deposition. PMID:26608736

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Yi; Dec, John E.; Sjoberg, Magnus

Modern spark-ignition (SI) engine technologies have considerably changed in-cylinder conditions under which fuel autoignition and engine knock take place. In this paper, fundamental HCCI engine experiments are proposed as a means for characterizing the impact of these technologies on the knock propensity of different fuels. In particular, the impacts of turbocharging, direct injection (DI), and downspeeding on operation with ethanol and gasoline are investigated to demonstrate this approach. Results reported earlier for ethanol and gasoline on HCCI combustion are revisited with the new perspective of how their autoignition characteristics fit into the anti-knock requirement in modern SI engines. For example,more » the weak sensitivity to pressure boost demonstrated by ethanol in HCCI autoignition can be used to explain the strong knock resistance of ethanol fuels for turbocharged SI engines. Further, ethanol's high sensitivity to charge temperature makes charge cooling, which can be produced by fuel vaporization via direct injection or by piston expansion via spark-timing retard, very effective for inhibiting knock. On the other hand, gasoline autoignition shows a higher sensitivity to pressure, so only very low pressure boost can be applied before knock occurs. Gasoline also demonstrates low temperature sensitivity, so it is unable to make as effective use of the charge cooling produced by fuel vaporization or spark retard. These arguments comprehensively explain literature results on ethanol's substantially better anti-knock performance over gasoline in modern turbocharged DISI engines. Fundamental HCCI experiments such as these can thus be used as a diagnostic and predictive tool for knock-limited SI engine performance for various fuels. As a result, examples are presented where HCCI experiments are used to identify biofuel compounds with good potential for modern SI-engine applications.« less

Role of endogenous insulin gene enhancer protein ISL-1 in angiogenesis

PubMed Central

Xiong, Si-qi; Jiang, Hai-bo; Li, Yan-xiu; Li, Hai-bo; Xu, Hui-zhuo; Wu, Zhen-kai; Zheng, Wei

2016-01-01

Objective To elucidate the role of insulin gene enhancer protein ISL-1 (Islet-1) in angiogenesis and regulation of vascular endothelial growth factor (VEGF) expression in vitro and in vivo. Methods siRNA targeting Islet-1 was transfected to human umbilical vein endothelial cell lines (HUVECs). The expression of Islet-1 and VEGF in the cultured cells was measured using real-time PCR and immunoblotting. 3-[4,5-dimethylthiazol-2-yl]-2,5- diphenyltetrazolium bromide; thiazolyl blue (MTT) assay was used to analyze the proliferation of HUVECs affected by Islet-1. Wound healing and Transwell assays were conducted to assess the motility of HUVECs. The formation of capillary-like structures was examined using growth factor–reduced Matrigel. siRNA targeting Islet-1 was intravitreally injected into the murine model of oxygen-induced retinopathy (OIR). Retinal neovascularization was evaluated with angiography using fluorescein-labeled dextran and then quantified histologically. Real-time PCR and immunoblotting were used to determine whether local Islet-1 silencing affected the expression of Islet-1 and VEGF in murine retinas. Results The expression of Islet-1 and VEGF in HUVECs was knocked down by siRNA. Reduced endogenous Islet-1 levels in cultured cells greatly inhibited the proliferation, migration, and tube formation in HUVECs in vitro. Retinal neovascularization following injection of Islet-1 siRNA was significantly reduced compared with that of the contralateral control eye. Histological analysis indicated that the neovascular nuclei protruding into the vitreous cavity were decreased. Furthermore, the Islet-1 and VEGF expression levels were downregulated in murine retinas treated with siRNA against Islet-1. Conclusions Reducing the expression of endogenous Islet-1 inhibits proliferation, migration, and tube formation in vascular endothelial cells in vitro and suppresses retinal angiogenesis in vivo. Endogenous Islet-1 regulates angiogenesis via VEGF. PMID:27994436

Fate and Distribution of 3H-Labeled T-2 Mycotoxin in Guinea Pigs

DTIC Science & Technology

1984-08-03

HPLC as well as TLC. . . of T-2 sycotox in guinea pigs. To establish the toxicity of an im injection of T-2 mycotoxin in the guinea pig, si:: ;A...that remained at the origin with p- glucuronidase , two additional less-polar radiolabeled peaks were smnarated by HPLC. This suggests that at least one...all tissues within 30 min - ’af.ter, an a injection" of, thr toxin. The rapi& reationff label suggests that toxic effects could begin shortly after

The central pattern generator underlying swimming in Dendronotus iris: a simple half-center network oscillator with a twist.

PubMed

Sakurai, Akira; Katz, Paul S

2016-10-01

The nudibranch mollusc, Dendronotus iris, swims by rhythmically flexing its body from left to right. We identified a bilaterally represented interneuron, Si3, that provides strong excitatory drive to the previously identified Si2, forming a half-center oscillator, which functions as the central pattern generator (CPG) underlying swimming. As with Si2, Si3 inhibited its contralateral counterpart and exhibited rhythmic bursts in left-right alternation during the swim motor pattern. Si3 burst almost synchronously with the contralateral Si2 and was coactive with the efferent impulse activity in the contralateral body wall nerve. Perturbation of bursting in either Si3 or Si2 by current injection halted or phase-shifted the swim motor pattern, suggesting that they are both critical CPG members. Neither Si2 nor Si3 exhibited endogenous bursting properties when activated alone; activation of all four neurons was necessary to initiate and maintain the swim motor pattern. Si3 made a strong excitatory synapse onto the contralateral Si2 to which it is also electrically coupled. When Si3 was firing tonically but not exhibiting bursting, artificial enhancement of the Si3-to-Si2 synapse using dynamic clamp caused all four neurons to burst. In contrast, negation of the Si3-to-Si2 synapse by dynamic clamp blocked ongoing swim motor patterns. Together, these results suggest that the Dendronotus swim CPG is organized as a "twisted" half-center oscillator in which each "half" is composed of two excitatory-coupled neurons from both sides of the brain, each of which inhibits its contralateral counterpart. Consisting of only four neurons, this is perhaps the simplest known network oscillator for locomotion. Copyright © 2016 the American Physiological Society.

Influence of Powder Metallurgical Processing Routes on Phase Formations in a Multicomponent NbSi-Alloy

NASA Astrophysics Data System (ADS)

Seemüller, C.; Hartwig, T.; Mulser, M.; Adkins, N.; Wickins, M.; Heilmaier, M.

2014-09-01

Refractory metal silicide composites on the basis of Nbss-Nb5Si3 have been investigated as potential alternatives for nickel-base superalloys for years because of their low densities and good high-temperature strengths. NbSi-based composites are typically produced by arc-melting or casting. Samples in this study, however, were produced by powder metallurgy because of the potential for near net-shape component fabrication with very homogeneous microstructures. Either gas atomized powder or high-energy mechanically alloyed elemental powders were compacted by powder injection molding or hot isostatic pressing. Heat treatments were applied for phase stability evaluation. Slight compositional changes (oxygen, nitrogen, or iron) introduced by the processing route, i.e., powder production and consolidation, can affect phase formations and phase transitions during the process. Special focus is put on the distinction between different silicides (Nb5Si3 and Nb3Si) and silicide modifications (α-, β-, and γ-Nb5Si3), respectively. These were evaluated by x-ray diffraction and energy-dispersive spectroscopy measurements with the additional inclusion of thermodynamic calculations using the calculated phase diagram method.

Impact of fluorescent silicon nanoparticles on circulating hemolymph and hematopoiesis in an invertebrate model organism.

PubMed

Xing, Rui; Li, Kai-Le; Zhou, Yan-Feng; Su, Yuan-Yuan; Yan, Si-Qi; Zhang, Kai-Long; Wu, Si-Cong; Sima, Yang-Hu; Zhang, Ke-Qin; He, Yao; Xu, Shi-Qing

2016-09-01

Silicon nanoparticles (SiNPs) have attractive potential applications in biological and medical fields, and yet their impact on animals is still controversial, and there have been no reports of their effects on hematopoiesis. In this study, the effects of SiNPs on hemocytes and hematopoiesis were investigated by administering SiNPs via a vascular injection into an invertebrate model, the silkworm. Our results show that the ability of SiNPs to enter different types of circulating hemocytes and their impact on those hemocytes differed significantly. Rapid accumulation of SiNPs was observed in granulocytes, oenocytoids, and spherulocytes, which have immune functions in the circulating hemolymph, whereas SiNPs did not easily enter prohemocytes, which can differentiate into granulocytes, oenocytoids, and spherulocytes and replenish them. The SiNPs that entered the hemocytes initiated autophagy and apoptosis via the lysosomal/mitochondrial pathway. High-dose SiNPs weakly stimulated lysosomal activity in hematopoietic organs, but did not lead to a significant increase in reactive oxygen species or severe autophagy or apoptosis in the organ tissues. We suggest that the damage caused by high-dose SiNPs to hematopoiesis is self-healing, because few SiNPs entered the hematopoietic stem cells in the circulating hemolymph, so the damage to the hematopoietic tissues was limited. Copyright © 2016 Elsevier Ltd. All rights reserved.

Communication: Visualization and spectroscopy of defects induced by dehydrogenation in individual silicon nanocrystals

NASA Astrophysics Data System (ADS)

Kislitsyn, Dmitry A.; Mills, Jon M.; Kocevski, Vancho; Chiu, Sheng-Kuei; DeBenedetti, William J. I.; Gervasi, Christian F.; Taber, Benjamen N.; Rosenfield, Ariel E.; Eriksson, Olle; Rusz, Ján; Goforth, Andrea M.; Nazin, George V.

2016-06-01

We present results of a scanning tunneling spectroscopy (STS) study of the impact of dehydrogenation on the electronic structures of hydrogen-passivated silicon nanocrystals (SiNCs) supported on the Au(111) surface. Gradual dehydrogenation is achieved by injecting high-energy electrons into individual SiNCs, which results, initially, in reduction of the electronic bandgap, and eventually produces midgap electronic states. We use theoretical calculations to show that the STS spectra of midgap states are consistent with the presence of silicon dangling bonds, which are found in different charge states. Our calculations also suggest that the observed initial reduction of the electronic bandgap is attributable to the SiNC surface reconstruction induced by conversion of surface dihydrides to monohydrides due to hydrogen desorption. Our results thus provide the first visualization of the SiNC electronic structure evolution induced by dehydrogenation and provide direct evidence for the existence of diverse dangling bond states on the SiNC surfaces.

A PET Design Based on SiPM and Monolithic LYSO Crystals: Performance Evaluation

NASA Astrophysics Data System (ADS)

González, Antonio J.; Aguilar, Albert; Conde, Pablo; Hernández, Liczandro; Moliner, Laura; Vidal, Luis F.; Sánchez, Filomeno; Sánchez, Sebastián; Correcher, Carlos; Molinos, César; Barberá, Julio; Lankes, Konrad; Junge, Sven; Bruckbauer, Thomas; Bruyndonckx, Peter; Benlloch, Jose M.

2016-10-01

A new small animal PET based on SiPM and monolithic LYSO crystals has been developed. Eight detector modules form the PET ring, each mounting an array of 12 × 12 SiPMs coupled to a readout providing the summed signals of the pixels on each of the 12 rows and 12 columns of the SiPM array. This design makes it possible to accurately determine the centroid of the scintillation light distribution with about 1.6 mm full width at half maximum (FWHM) resolution without correction for the 1 mm source size, and the photon depth of interaction (DOI) with nearly 2 mm FWHM. This single ring PET system has a homogeneous spatial resolution across the entire 80 mm transaxial field of view (FOV) of about 1 mm FWHM. The noise equivalent count rate (NECR) peak is estimated to occur at around 39.2 MBq with a rate of approximately 82.7 kcps for the mouse-like phantom and 22 kcps at 48.1 MBq for the rat-like phantom. Following the NEMA protocol, the peak absolute sensitivity in the center of the FOV is 2.8% for a 30% peak energy window. A pilot test injecting NaF to a mouse of 20 grams is also presented. Finally, the PET ring has been tested in front of a high field 15.2 T Magnetic Resonance (MR). No significant variation on energy and spatial resolution across the FOV has been observed due to the presence of the magnetic field.

Improved silicon nitride for advanced heat engines

NASA Technical Reports Server (NTRS)

Yeh, H. C.; Wimmer, J. M.; Huang, H. H.; Rorabaugh, M. E.; Schienle, J.; Styhr, K. H.

1985-01-01

The AiResearch Casting Company baseline silicon nitride (92 percent GTE SN-502 Si sub 3 N sub 4 plus 6 percent Y sub 2 O sub 3 plus 2 percent Al sub 2 O sub 3) was characterized with methods that included chemical analysis, oxygen content determination, electrophoresis, particle size distribution analysis, surface area determination, and analysis of the degree of agglomeration and maximum particle size of elutriated powder. Test bars were injection molded and processed through sintering at 0.68 MPa (100 psi) of nitrogen. The as-sintered test bars were evaluated by X-ray phase analysis, room and elevated temperature modulus of rupture strength, Weibull modulus, stress rupture, strength after oxidation, fracture origins, microstructure, and density from quantities of samples sufficiently large to generate statistically valid results. A series of small test matrices were conducted to study the effects and interactions of processing parameters which included raw materials, binder systems, binder removal cycles, injection molding temperatures, particle size distribution, sintering additives, and sintering cycle parameters.

Dynamic NMDAR-mediated properties of place cells during the object place memory task.

PubMed

Faust, Thomas W; Robbiati, Sergio; Huerta, Tomás S; Huerta, Patricio T

2013-01-01

N-methyl-D-aspartate receptors (NMDAR) in the hippocampus participate in encoding and recalling the location of objects in the environment, but the ensemble mechanisms by which NMDARs mediate these processes have not been completely elucidated. To address this issue, we examined the firing patterns of place cells in the dorsal CA1 area of the hippocampus of mice (n = 7) that performed an object place memory (OPM) task, consisting of familiarization (T1), sample (T2), and choice (T3) trials, after systemic injection of 3-[(±)2-carboxypiperazin-4yl]propyl-1-phosphate (CPP), a specific NMDAR antagonist. Place cell properties under CPP (CPP-PCs) were compared to those after control saline injection (SAL-PCs) in the same mice. We analyzed place cells across the OPM task to determine whether they signaled the introduction or movement of objects by NMDAR-mediated changes of their spatial coding. On T2, when two objects were first introduced to a familiar chamber, CPP-PCs and SAL-PCs showed stable, vanishing or moving place fields in addition to changes in spatial information (SI). These metrics were comparable between groups. Remarkably, previously inactive CPP-PCs (with place fields emerging de novo on T2) had significantly weaker SI increases than SAL-PCs. On T3, when one object was moved, CPP-PCs showed reduced center-of-mass (COM) shift of their place fields. Indeed, a subset of SAL-PCs with large COM shifts (>7 cm) was largely absent in the CPP condition. Notably, for SAL-PCs that exhibited COM shifts, those initially close to the moving object followed the trajectory of the object, whereas those far from the object did the opposite. Our results strongly suggest that the SI changes and COM shifts of place fields that occur during the OPM task reflect key dynamic properties that are mediated by NMDARs and might be responsible for binding object identity with location.

Dynamic NMDAR-mediated properties of place cells during the object place memory task

PubMed Central

Faust, Thomas W.; Robbiati, Sergio; Huerta, Tomás S.; Huerta, Patricio T.

2013-01-01

N-methyl-D-aspartate receptors (NMDAR) in the hippocampus participate in encoding and recalling the location of objects in the environment, but the ensemble mechanisms by which NMDARs mediate these processes have not been completely elucidated. To address this issue, we examined the firing patterns of place cells in the dorsal CA1 area of the hippocampus of mice (n = 7) that performed an object place memory (OPM) task, consisting of familiarization (T1), sample (T2), and choice (T3) trials, after systemic injection of 3-[(±)2-carboxypiperazin-4yl]propyl-1-phosphate (CPP), a specific NMDAR antagonist. Place cell properties under CPP (CPP–PCs) were compared to those after control saline injection (SAL–PCs) in the same mice. We analyzed place cells across the OPM task to determine whether they signaled the introduction or movement of objects by NMDAR-mediated changes of their spatial coding. On T2, when two objects were first introduced to a familiar chamber, CPP–PCs and SAL–PCs showed stable, vanishing or moving place fields in addition to changes in spatial information (SI). These metrics were comparable between groups. Remarkably, previously inactive CPP–PCs (with place fields emerging de novo on T2) had significantly weaker SI increases than SAL–PCs. On T3, when one object was moved, CPP–PCs showed reduced center-of-mass (COM) shift of their place fields. Indeed, a subset of SAL–PCs with large COM shifts (>7 cm) was largely absent in the CPP condition. Notably, for SAL–PCs that exhibited COM shifts, those initially close to the moving object followed the trajectory of the object, whereas those far from the object did the opposite. Our results strongly suggest that the SI changes and COM shifts of place fields that occur during the OPM task reflect key dynamic properties that are mediated by NMDARs and might be responsible for binding object identity with location. PMID:24381547

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seth, Arpan; Klise, Katherine A.; Siirola, John D.

In the event of contamination in a water distribution network (WDN), source identification (SI) methods that analyze sensor data can be used to identify the source location(s). Knowledge of the source location and characteristics are important to inform contamination control and cleanup operations. Various SI strategies that have been developed by researchers differ in their underlying assumptions and solution techniques. The following manuscript presents a systematic procedure for testing and evaluating SI methods. The performance of these SI methods is affected by various factors including the size of WDN model, measurement error, modeling error, time and number of contaminant injections,more » and time and number of measurements. This paper includes test cases that vary these factors and evaluates three SI methods on the basis of accuracy and specificity. The tests are used to review and compare these different SI methods, highlighting their strengths in handling various identification scenarios. These SI methods and a testing framework that includes the test cases and analysis tools presented in this paper have been integrated into EPA’s Water Security Toolkit (WST), a suite of software tools to help researchers and others in the water industry evaluate and plan various response strategies in case of a contamination incident. Lastly, a set of recommendations are made for users to consider when working with different categories of SI methods.« less

Double loaded self-decomposable SiO2 nanoparticles for sustained drug release

NASA Astrophysics Data System (ADS)

Zhao, Saisai; Zhang, Silu; Ma, Jiang; Fan, Li; Yin, Chun; Lin, Ge; Li, Quan

2015-10-01

Sustained drug release for a long duration is a desired feature of modern drugs. Using double-loaded self-decomposable SiO2 nanoparticles, we demonstrated sustained drug release in a controllable manner. The double loading of the drugs was achieved using two different mechanisms--the first one via a co-growth mechanism, and the second one by absorption. A two-phase sustained drug release was firstly revealed in an in vitro system, and then further demonstrated in mice. After a single intravenous injection, the drug was controllably released from the nanoparticles into blood circulation with a Tmax of about 8 h, afterwards a long lasting release pattern was achieved to maintain drug systemic exposure with a plasma elimination half-life of approximately 28 h. We disclosed that the absorbed drug molecules contributed to the initial fast release for quickly reaching the therapeutic level with relatively higher plasma concentrations, while the ``grown-in'' drugs were responsible for maintaining the therapeutic level via the later controlled slow and sustained release. The present nanoparticle carrier drug configuration and the loading/maintenance release mechanisms provide a promising platform that ensures a prolonged therapeutic effect by controlling drug concentrations within the therapeutic window--a sustained drug delivery system with a great impact on improving the management of chronic diseases.Sustained drug release for a long duration is a desired feature of modern drugs. Using double-loaded self-decomposable SiO2 nanoparticles, we demonstrated sustained drug release in a controllable manner. The double loading of the drugs was achieved using two different mechanisms--the first one via a co-growth mechanism, and the second one by absorption. A two-phase sustained drug release was firstly revealed in an in vitro system, and then further demonstrated in mice. After a single intravenous injection, the drug was controllably released from the nanoparticles into blood circulation with a Tmax of about 8 h, afterwards a long lasting release pattern was achieved to maintain drug systemic exposure with a plasma elimination half-life of approximately 28 h. We disclosed that the absorbed drug molecules contributed to the initial fast release for quickly reaching the therapeutic level with relatively higher plasma concentrations, while the ``grown-in'' drugs were responsible for maintaining the therapeutic level via the later controlled slow and sustained release. The present nanoparticle carrier drug configuration and the loading/maintenance release mechanisms provide a promising platform that ensures a prolonged therapeutic effect by controlling drug concentrations within the therapeutic window--a sustained drug delivery system with a great impact on improving the management of chronic diseases. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr03029c

Green electroluminescence from Tb{sub 4}O{sub 7} films on silicon: Impact excitation of Tb{sup 3+} ions by hot carriers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Chen; Jiang, Miaomiao; Zhou, Junwei

2016-02-01

We report on green electroluminescence (EL) due to the intra-4f transitions of the trivalent terbium (Tb{sup 3+}) ions inherent in a Tb{sub 4}O{sub 7} film that is sandwiched between the ITO film and heavily phosphorous- or boron-doped silicon (n{sup +}-Si or p{sup +}-Si) substrate, thus forming the so-called metal-oxide-semiconductor (MOS) device. The onset voltage of such EL is below 10 V. From the current-voltage characteristic and voltage-dependent EL spectra of the aforementioned MOS device, it is derived that the Tb-related green EL results from the impact excitation of Tb{sup 3+} ions by the hot electrons (holes), which stem from the electric-fieldmore » acceleration of the electrons (holes) injected from the n{sup +}-Si (p{sup +}-Si) substrate via the trap-assisted tunneling mechanism.« less

Facile Synthesis of γ-In2 Se3 Nanoflowers toward High Performance Self-Powered Broadband γ-In2 Se3 /Si Heterojunction Photodiode.

PubMed

Chen, Shuo; Liu, Xuemei; Qiao, Xvsheng; Wan, Xia; Shehzad, Khurram; Zhang, Xianghua; Xu, Yang; Fan, Xianping

2017-05-01

An effective colloidal process involving the hot-injection method is developed to synthesize uniform nanoflowers consisting of 2D γ-In 2 Se 3 nanosheets. By exploiting the narrow direct bandgap and high absorption coefficient in the visible light range of In 2 Se 3 , a high-quality γ-In 2 Se 3 /Si heterojunction photodiode is fabricated. This photodiode shows a high photoresponse under light illumination, short response/recovery times, and long-term durability. In addition, the γ-In 2 Se 3 /Si heterojunction photodiode is self-powered and displays a broadband spectral response ranging from UV to IR with a high responsivity and detectivity. These excellent performances make the γ-In 2 Se 3 /Si heterojunction very interesting as highly efficient photodetectors. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Effect of DJ-1 silencing by RNA interference on growth of xenografted human laryngeal squamous cell carcinoma Hep-2 cells in nude mice].

PubMed

Shen, Zhisen; Deng, Hongxia; Ye, Dong; Zhang, Jian; Qiu, Shijie; Li, Qun; Cui, Xiang

2016-05-25

Objective: To investigate the effect of silencing DJ-1 on xenografted human laryngeal squamous cell carcinoma (LSCC) Hep-2 cells in nude mice. Methods: Xenograft model of human LSCC was established by subcutaneous transplantation of Hep-2 cells in 24 nude mice. The LSCC-bearing nude mice were randomly divided into 3 groups ( n =8 in each):DJ-1 siRNA low dose group and DJ-1 siRNA high dose group were injected in tumors with 20 μg of DJ-1 siRNA or 40 μg of DJ-1 siRNA in 50 μL, respectively; control group was injected with 5% glucose solution in 50 μL, twice a week for 3 weeks. The weight and size of tumors were measured before injection. The animals were sacrificed 48 h after the final treatment, and the tumors were harvested and weighed. The apoptosis and proliferation of tumor cells were determined; the expressions of Caspase-3 and Ki-67 in tumor specimens were detected with immunohistochemistry. The expression of DJ-1, PTEN, survivin mRNA and protein in tumor tissues were detected by RT-PCR and Western blotting, respectively. Results: Tumor weight in low dose group[(0.66±0.15)g] and high dose group[(0.48±0.11)g] were significantly lower than that in control group[(0.83±0.16)g, all P <0.05]. The inhibition rates of low dose group and high dose group were (20.48±0.18)% and (42.16±0.13)%, respectively. Immunohistochemistry showed that the expression of Caspase-3 was increased and Ki-67 was reduced in tumor specimens, compared with the control group (all P <0.05). RT-PCR and Western blot results showed that in low dose group and high dose group the mRNA and protein expression of DJ-1 and survivin significantly decreased (all P <0.05), while PTEN mRNA and protein content increased (all P <0.05). Conclusion: High dose DJ-1 siRNA can inhibit the tumor growth in human LSCC xenograft nude mouse model, which indicates that down-regulating DJ-1 and survivin, and up-regulating PTEN expression may lead to blockage of PI3K-PKB/Akt signaling pathway and promoting tumor cell apoptosis.

Nonviral pulmonary delivery of siRNA.

PubMed

Merkel, Olivia M; Kissel, Thomas

2012-07-17

RNA interference (RNAi) is an important part of the cell's defenses against viruses and other foreign genes. Moreover, the biotechnological exploitation of RNAi offers therapeutic potential for a range of diseases for which drugs are currently unavailable. Unfortunately, the small interfering RNAs (siRNAs) that are central to RNAi in the cytoplasm are readily degradable by ubiquitous nucleases, are inefficiently targeted to desired organs and cell types, and are excreted quickly upon systemic injection. As a result, local administration techniques have been favored over the past few years, resulting in great success in the treatment of viral infections and other respiratory disorders. Because there are several advantages of pulmonary delivery over systemic administration, two of the four siRNA drugs currently in phase II clinical trials are delivered intranasally or by inhalation. The air-blood barrier, however, has only limited permeability toward large, hydrophilic biopharmaceuticals such as nucleic acids; in addition, the lung imposes intrinsic hurdles to efficient siRNA delivery. Thus, appropriate formulations and delivery devices are very much needed. Although many different formulations have been optimized for in vitro siRNA delivery to lung cells, only a few have been reported successful in vivo. In this Account, we discuss both obstacles to pulmonary siRNA delivery and the success stories that have been achieved thus far. The optimal pulmonary delivery vehicle should be neither cytotoxic nor immunogenic, should protect the payload from degradation by nucleases during the delivery process, and should mediate the intracellular uptake of siRNA. Further requirements include the improvement of the pharmacokinetics and lung distribution profiles of siRNA, the extension of lung retention times (through reduced recognition by macrophages), and the incorporation of reversible or stimuli-responsive binding of siRNA to allow for efficient release of the siRNAs at the target site. In addition, the ideal carrier would be biodegradable (to address difficulties with repeated administration for the treatment of chronic diseases) and would contain targeting moieties to enhance uptake by specific cell types. None of the currently available polymer- and lipid-based formulations meet every one of these requirements, but we introduce here several promising new approaches, including a biodegradable, nonimmunogenic polyester. We also discuss imaging techniques for following the biodistribution according to the administration route. This tracking is crucial for better understanding the translocation and clearance of nanoformulated siRNA subsequent to pulmonary delivery. In the literature, the success of pulmonary siRNA delivery is evaluated solely by relief from or prophylaxis against a disease; side effects are not studied in detail. It also remains unclear which cell types in the lung eventually take up siRNA. These are critical issues for the translational use of pulmonary siRNA formulations; accordingly, we present a flow cytometry technique that can be utilized to differentiate transfected cell populations in a mouse model that expresses transgenic enhanced green fluorescence protein (EGFP). This technique, in which different cell types are identified on the basis of their surface antigen expression, may eventually help in the development of safer carriers with minimized side effects in nontargeted tissues.

Effect of the chamber wall on fluorocarbon-assisted atomic layer etching of SiO{sub 2} using cyclic Ar/C{sub 4}F{sub 8} plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kawakami, Masatoshi; Metzler, Dominik; Oehrlein, Gottlieb S., E-mail: oehrlein@umd.edu

2016-07-15

The authors studied the effect of the temperature and chemical state of the chamber wall on process performance for atomic layer etching of SiO{sub 2} using a steady-state Ar plasma, periodic injection of a defined number of C{sub 4}F{sub 8} molecules, and synchronized plasma-based Ar{sup +} ion bombardment. To evaluate these effects, the authors measured the quartz coupling window temperature. The plasma gas phase chemistry was characterized using optical emission spectroscopy. It was found that although the thickness of the polymer film deposited in each cycle is constant, the etching behavior changed, which is likely related to a change inmore » the plasma gas phase chemistry. The authors found that the main gas phase changes occur after C{sub 4}F{sub 8} injection. The C{sub 4}F{sub 8} and the quartz window react and generate SiF and CO. The emission intensity changes with wall surface state and temperature. Therefore, changes in the plasma gas species generation can lead to a shift in etching performance during processing. During initial cycles, minimal etching is observed, while etching gradually increases with cycle number.« less

Neurokinin B-producing projection neurons in the lateral stripe of the striatum and cell clusters of the accumbens nucleus in the rat.

PubMed

Zhou, Ligang; Furuta, Takahiro; Kaneko, Takeshi

2004-12-06

Neurons producing preprotachykinin B (PPTB), the precursor of neurokinin B, constitute 5% of neurons in the dorsal striatum and project to the substantia innominata (SI) selectively. In the ventral striatum, PPTB-producing neurons are collected mainly in the lateral stripe of the striatum (LSS) and cell clusters of the accumbens nucleus (Acb). In the present study, we first examined the distribution of PPTB-immunoreactive neurons in rat ventral striatum and found that a large part of the PPTB-immunoreactive cell clusters was continuous to the LSS, but a smaller part was not. Thus, we divided the PPTB-immunoreactive cell clusters into the LSS-associated and non-LSS-associated ones. We next investigated the projection targets of the PPTB-producing ventral striatal neurons by combining immunofluorescence labeling and retrograde tracing. After injection of Fluoro-Gold into the basal component of the SI (SIb) and medial part of the interstitial nucleus of posterior limb of the anterior commissure, many PPTB-immunoreactive neurons were retrogradely labeled in the LSS-associated cell clusters and LSS, respectively. When the injection site included the ventral part of the sublenticular component of the SI(SIsl), retrogradely labeled neurons showed PPTB-immunoreactivity frequently in non-LSS-associated cell clusters. Furthermore, these PPTB-immunoreactive projections were confirmed by the double-fluorescence method after anterograde tracer injection into the ventral striatum containing the cell clusters. Since the dorsalmost part of the SIsl is known to receive strong inputs from PPTB-producing dorsal striatal neurons, the present results indicate that PPTB-producing ventral striatal neurons project to basal forebrain target regions in parallel with dorsal striatal neurons without significant convergence. 2004 Wiley-Liss, Inc.

Background reduction in 236U/238U measurements

NASA Astrophysics Data System (ADS)

Buompane, Raffaele; De Cesare, Mario; De Cesare, Nicola; Di Leva, Antonino; D'Onofrio, Antonio; Fifield, L. Keith; Fröhlich, Michaela; Gialanella, Lucio; Marzaioli, Fabio; Sabbarese, Carlo; Terrasi, Filippo; Tims, Stephen; Wallner, Anton

2015-10-01

The measurements of actinide isotopic ratios, in particular 236U/238U, in environmental samples requires high sensitivity. In particular, special effort must be devoted to the suppression of interfering nuclides, such as 235,238U, when measuring 236U. At the AMS facility of CIRCE, isotopic ratios down to ∼10-10 are currently measured using a gas E - ΔE detector. In order to push this limit lower towards natural levels, a time-of-flight system is used, featuring a micro-channel plate start detector and a Si stop detector. As the mass resolution of the latter is limited by the layout, an attempt to reduce the abundant isotope interference by other means has been undertaken. In this study, we report preliminary results on the characterization of the presence of molecular interferences when using UO-, UC- and UC2- as injected molecular ions. In particular the possibility to stabilize the current yield from carbide cathodes has been investigated: it was found that the best cathode preparation procedure is obtained pressing U salts baked at 800 °C mixed with graphite and Al powder. Moreover, the 238U background in 236U measurements is strongly reduced injecting UC- ions, as verified using a time-of-flight detection system. On the other hand, 235U interference is larger with respect to UO- injection, but this increase is smaller than expected on the basis of abundances of 13C and 17O in UC and UC2 molecules on one side and UO, on the other.

Miniature Gas-Turbine Power Generator

NASA Technical Reports Server (NTRS)

Wiberg, Dean; Vargo, Stephen; White, Victor; Shcheglov, Kirill

2003-01-01

A proposed microelectromechanical system (MEMS) containing a closed- Brayton-cycle turbine would serve as a prototype of electric-power generators for special applications in which high energy densities are required and in which, heretofore, batteries have been used. The system would have a volume of about 6 cm3 and would operate with a thermal efficiency >30 percent, generating up to 50 W of electrical power. The energy density of the proposed system would be about 10 times that of the best battery-based systems now available, and, as such, would be comparable to that of a fuel cell. The working gas for the turbine would be Xe containing small quantities of CO2, O2, and H2O as gaseous lubricants. The gas would be contained in an enclosed circulation system, within which the pressure would typically range between 5 and 50 atm (between 0.5 and 5 MPa). The heat for the Brayton cycle could be supplied by any of a number of sources, including a solar concentrator or a combustor burning a hydrocarbon or other fuel. The system would include novel heat-transfer and heat-management components. The turbine would be connected to an electric power generator/starter motor. The system would include a main rotor shaft with gas bearings; the bearing surfaces would be made of a ceramic material coated with nanocrystalline diamond. The shaft could withstand speed of 400,000 rpm or perhaps more, with bearing-wear rates less than 10(exp -)4 those of silicon bearings and 0.05 to 0.1 those of SiC bearings, and with a coefficient of friction about 0.1 that of Si or SiC bearings. The components of the system would be fabricated by a combination of (1) three-dimensional xray lithography and (2) highly precise injection molding of diamond-compatible metals and ceramic materials. The materials and fabrication techniques would be suitable for mass production. The disadvantages of the proposed system are that unlike a battery-based system, it could generate a perceptible amount of sound, and, if it were to burn fuel, then it would also generate exhaust, similarly to other combustion-based power sources.

Allergoid-specific T-cell reaction as a measure of the immunological response to specific immunotherapy (SIT) with a Th1-adjuvanted allergy vaccine.

PubMed

von Baehr, V; Hermes, A; von Baehr, R; Scherf, H P; Volk, H D; Fischer von Weikersthal-Drachenberg, K J; Woroniecki, S

2005-01-01

Specific immunotherapy (SIT) is believed to modulate CD4+ T-helper cells. In order to improve safety, SIT vaccines are often formulated with allergoids (chemically modified allergens). Interaction between T-cells and allergoids is necessary to influence cellular cytokine expression. There have been few reports on identification the early cellular effects of SIT. Patients allergic to grass and/or mugwort pollen (n= 21) were treated with a 4-shot allergy vaccine (Pollinex Quattro) containing appropriate allergoids (grass/rye and/or mugwort) adsorbed to L-tyrosine plus a Th1 adjuvant, monophosphoryl lipid A (MPL). Fourteen grass-allergic patients served as untreated controls. Using the peripheral blood mononuclear cells of these patients, an optimized lymphocyte transformation test (LTT) was employed to monitor the in vitro proliferative response of T-cells to an allergoid challenge (solubilised Pollinex Quattro) before the first and last injection and then 2 and 20 weeks after the final injection. Control challenges utilised preparations of a similar pollen vaccine without the adjuvant MPL and a tree pollen vaccine with and without MPL. The LTT showed increased LTT stimulation indices (SI) in 17/20 SIT patients when the solublised vaccine preparation was used as a challenge before the last injection and 2 weeks after, in comparison to pre-treatment levels. Twenty weeks after therapy, the SI decreased to baseline level. A vaccine challenge without MPL gave lower SI levels. A challenge of a clinically inappropriate tree allergoid vaccine gave no response, and a nontreated group also showed no response. Following a short-course SIT adjuvated with MPL, challenges of allergoids were shown to activate allergen-specific T cells in vitro. There was an additional stimulating effect when the challenge was in combination with MPL. There were no non-specific effects of MPL, shown by the tree allergoid/MPL control. The timing of the response was closely correlated to the treatment course; reactivity fell two weeks after the final injection and 20 weeks later it was at baseline level. Thus an immunological response to SIT was detected after very few injections. This methodology could provide a basis for monitoring the immediate progress of allergy vaccinations.

Requirement of alveolar bone formation for eruption of rat molars

PubMed Central

Wise, Gary E.; He, Hongzhi; Gutierrez, Dina L.; Ring, Sherry; Yao, Shaomian

2011-01-01

Tooth eruption is a localized event that requires a dental follicle (DF) to regulate the resorption of alveolar bone to form an eruption pathway. During the intra-osseous phase of eruption, the tooth moves through this pathway. The mechanism or motive force that propels the tooth through this pathway is controversial but many studies have shown that alveolar bone growth at the base of the crypt occurs during eruption. To determine if this bone growth (osteogenesis) was causal, experiments were designed in which the expression of an osteogenic gene in the DF, bone morphogenetic protein-6 (BMP6), was inhibited by injection of the 1st mandibular molar of the rat with an siRNA targeted against BMP6. The injection was followed by electroporation to promote uptake of the siRNA. In 45 first molars injected, eruption either was delayed or completely inhibited (7 molars). In the impacted molars, an eruption pathway formed but bone growth at the base of the crypt was greatly reduced as compared to the erupted first molar controls. These studies show that alveolar bone growth at the base of the crypt is required for tooth eruption and that BMP6 may be an essential gene for promoting this growth. PMID:21896048

Microstructure and High Temperature Oxidation Property of Fe-Cr-B Based Metal/Ceramic Composite Manufactured by Powder Injection Molding Process

NASA Astrophysics Data System (ADS)

Joo, Yeun-Ah; Kim, Young-Kyun; Yoon, Tae-Sik; Lee, Kee-Ahn

2018-03-01

This study investigated the microstructure and high temperature oxidation property of Fe-Cr-B metal/ceramic composite manufactured using powder injection molding process. Observations of initial microstructure showed a unique structure where α-Fe and (Cr, Fe)2B form a continuous three-dimensional network. High temperature oxidation tests were performed at 900, 1000 and 1100 °C, for 24 h, and the oxidation weight gain according to each temperature condition was 0.13, 0.84 and 6.4 mg/cm2, respectively. The oxidation results according to time at 900 and 1000 °C conditions represented parabolic curves, and at 1100 °C condition formed a rectilinear curve. Observation and phase analysis results of the oxides identified Cr2O3 and SiO2 at 900 and 1000 °C. In addition to Cr2O3 and SiO2, CrBO3 and FeCr2O4 formed due to phase decomposition of boride were identified at 1100 °C. Based on the findings above, this study suggested the high temperature oxidation mechanism of Fe-Cr-B metal/ceramic composite manufactured using powder injection molding, and the possibility of its application as a high temperature component material was also discussed.

Human Papillomavirus E6/E7-Specific siRNA Potentiates the Effect of Radiotherapy for Cervical Cancer in Vitro and in Vivo

PubMed Central

Jung, Hun Soon; Rajasekaran, Nirmal; Song, Sang Yong; Kim, Young Deug; Hong, Sungyoul; Choi, Hyuck Jae; Kim, Young Seok; Choi, Jong-Sun; Choi, Yoon-La; Shin, Young Kee

2015-01-01

The functional inactivation of TP53 and Rb tumor suppressor proteins by the HPV-derived E6 and E7 oncoproteins is likely an important step in cervical carcinogenesis. We have previously shown siRNA technology to selectively silence both E6/E7 oncogenes and demonstrated that the synthetic siRNAs could specifically block its expression in HPV-positive cervical cancer cells. Herein, we investigated the potentiality of E6/E7 siRNA candidates as radiosensitizers of radiotherapy for the human cervical carcinomas. HeLa and SiHa cells were transfected with HPV E6/E7 siRNA; the combined cytotoxic effect of E6/E7 siRNA and radiation was assessed by using the cell viability assay, flow cytometric analysis and the senescence-associated β-galactosidase (SA-β-Gal) assay. In addition, we also investigated the effect of combined therapy with irradiation and E6/E7 siRNA intravenous injection in an in vivo xenograft model. Combination therapy with siRNA and irradiation efficiently retarded tumor growth in established tumors of human cervical cancer cell xenografted mice. In addition, the chemically-modified HPV16 and 18 E6/E7 pooled siRNA in combination with irradiation strongly inhibited the growth of cervical cancer cells. Our results indicated that simultaneous inhibition of HPV E6/E7 oncogene expression with radiotherapy can promote potent antitumor activity and radiosensitizing activity in human cervical carcinomas. PMID:26035754

Topics in LIFE Target Survival: 11-SI-004 Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miles, Robin; Benett, Bill; Bond, Tiziana

The LIFE target design incorporates many considerations to generate the desired fusion gain including the physics design, the cost of manufacturing of the target, the injectability of the target, the aerodynamic flight characteristics of the target, the ability to track and engage the target and to maintain the structural and thermal integrity of the target. This document describes the effort that was made in support of issues of survivability of the target during injection which included issues massmanufactural materials and processes which could be used in the target.

Inhibition of Androgen-Independent Growth of Prostate Cancer by siRNA-Mediated Androgen Receptor Gene Silencing

DTIC Science & Technology

2006-02-01

was gradually increased along with increasing dosage of the AAV.ARHP8 particles injected. No GFP expression was observed in PBS-injected xenograft...receptor. Cancer Gene Ther 2002;9:117–25. 16. Craft N, Shostak Y , Carey M, Sawyers CL. A mechanism for hormone- independent prostate cancer through...modulation of androgen receptor signaling by the HER-2/neu tyrosine kinase. Nat Med 1999;5:280–5. 17. Wen Y , Hu MC, Makino K, et al. HER-2/neu promotes

Mucin-mediated nanocarrier disassembly for triggered uptake of oligonucleotides as a delivery strategy for the potential treatment of mucosal tumours

NASA Astrophysics Data System (ADS)

Martirosyan, A.; Olesen, M. J.; Fenton, R. A.; Kjems, J.; Howard, K. A.

2016-06-01

This work demonstrates gastric mucin-triggered nanocarrier disassembly for release of antisense oligonucleotides and consequent unassisted cellular entry as a novel oral delivery strategy. A fluorescence activation-based reporter system was used to investigate the interaction and mucin-mediated disassembly of chitosan-based nanocarriers containing a 13-mer DNA oligonucleotide with a flanked locked RNA nucleic acid gapmer design. Gastric mucins were shown to trigger gapmer release from nanocarriers that was dependent on the interaction time, mucin concentration and N : P ratio with a maximal release at N : P 10. In contrast to siRNA, naked gapmers exhibited uptake into mucus producing HT-MTX mono-cultures and HT-MTX co-cultured with the carcinoma epithelial cell line Caco-2. Importantly, in vivo gapmer uptake was observed in epithelial tissue 30 min post-injection in murine intestinal loops. The findings present a mucosal design-based system tailored for local delivery of oligonucleotides that may maximize the effectiveness of gene silencing therapeutics within tumours at mucosal sites.This work demonstrates gastric mucin-triggered nanocarrier disassembly for release of antisense oligonucleotides and consequent unassisted cellular entry as a novel oral delivery strategy. A fluorescence activation-based reporter system was used to investigate the interaction and mucin-mediated disassembly of chitosan-based nanocarriers containing a 13-mer DNA oligonucleotide with a flanked locked RNA nucleic acid gapmer design. Gastric mucins were shown to trigger gapmer release from nanocarriers that was dependent on the interaction time, mucin concentration and N : P ratio with a maximal release at N : P 10. In contrast to siRNA, naked gapmers exhibited uptake into mucus producing HT-MTX mono-cultures and HT-MTX co-cultured with the carcinoma epithelial cell line Caco-2. Importantly, in vivo gapmer uptake was observed in epithelial tissue 30 min post-injection in murine intestinal loops. The findings present a mucosal design-based system tailored for local delivery of oligonucleotides that may maximize the effectiveness of gene silencing therapeutics within tumours at mucosal sites. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07206a

Strategic information is everyone's business: perspectives from an international stakeholder meeting to enhance strategic information data along the HIV Cascade for people who inject drugs.

PubMed

Pierce, Richard D; Hegle, Jennifer; Sabin, Keith; Agustian, Edo; Johnston, Lisa G; Mills, Stephen; Todd, Catherine S

2015-10-16

People who inject drugs (PWID) are at increased HIV transmission risk because of unsafe injecting practices and a host of other individual, network, and structural factors. Thus, PWID have a great need for services within the Cascade of HIV prevention, diagnosis, care, and treatment (HIV Cascade). Yet the systems that monitor their progress through the Cascade are often lacking. Subsequently, fewer reliable data are available to guide programs targeting this key population (KP). Programmatic data, which are helpful in tracking PWID through the Cascade, also are limited because not all countries have harm reduction programming from which to estimate Cascade indicators. Also, due to stigma and the illegal nature of drug use, PWID may not disclose their drug use behavior or HIV status when accessing services. Consequently, PWID appear to have low HIV testing rates and, for those living with HIV, lower access to health services and lower viral suppression rates than do other KP groups. This commentary, based on outcomes from an international stakeholder meeting, identifies data gaps and proposes solutions to strengthen strategic information (SI), the systematic collection, analysis, and dissemination of information, to optimize HIV prevention, care, and treatment programming for PWID.

Experimental investigations of quantum confined silicon nanoparticle light emitting devices

NASA Astrophysics Data System (ADS)

Ligman, Rebekah Kristine

2007-12-01

As the demands on our world's energy resources continue to grow, alternative high efficiency materials such as quantum confined silicon nanoparticles (Si nps) are desirable for their potential low cost application in white light illumination, in optical displays, and in on-chip optical interconnects. Many fabrication and passivation techniques exist that produce Si nps with high photogenerated quantum yield. However, high electrically generated Si np quantum efficiency has eluded our society. Predominantly due to the lack of a stable surface passivation and a device fabrication technique that preserves the Si np optical properties. To amend these deficiencies, the passivation of nonthermal plasma fabricated Si nps with a surface oxide grown under UV exposure was first investigated. Control over the surface oxidized Si np (Si/SiO2) passivation growth was demonstrated and the optical stability of Si/SiO2 nps was suitable for demonstrating Si np electroluminescence (EL). Two approaches for constructing hybrid organic light emitting diode (OLED) devices around nonthermal plasma fabricated Si nps were then investigated. Multilayer devices, composed of a nonthermal plasma fabricated Si np layer embedded within an OLED, were first studied. However, no EL from Si nps was obtained using the multilayer device architecture due to poor control over the Si np film thickness. Single layer polymer(Si/SiO2) hybrid devices, composed of nps randomly dispersed within an extrinsic conductive polymer, were then studied and EL from Si/SiO2 nps was obtained. The hybrid device optical and electrical response was enhanced over the control devices, possibly due to morphology changes induced by the Si/SiO2 nps. The energy transfer (ET) processes in single layer polymer(Si/SiO 2) hybrid devices were then investigated by imposing known spatial separations between the intrinsic conductive polymers and Si/SiO2 nps. No measurable Si/SiO2 np emission was observed from the intrinsic hybrid devices independent of the spatial separation, implying no ET occurs between the intrinsic polymers and Si/SiO2 nps. These results suggest the observed Si/SiO 2 np emission from extrinsic polymer(Si/SiO2) hybrid devices may be produced by direct carrier injection, Forster or Dexter ET mechanisms.

Thermodynamic design of a high temperature chemical vapor deposition process to synthesize α-SiC in Si-C-H and Si-C-H-Cl systems

NASA Astrophysics Data System (ADS)

Kang, Yura; Yoo, Chang-Hyoung; Nam, Deok-Hui; Lee, Myung-Hyun; Seo, Won-Seon; Hong, Suklyun; Jeong, Seong-Min

2018-03-01

In this study, we thermodynamically reviewed the suitable growth process conditions of α-SiC in the Si-C-H system using tetramethylsilane (TMS) and in the Si-C-H-Cl system using methyltrichlorosilane (MTS). In the Si-C-H-Cl system, pure solid SiC was obtained at high temperatures under a larger range of hydrogen dilution ratios than that tolerated in the Si-C-H system. X-ray diffraction and micro-Raman analysis of the products obtained at 1900, 2000, and 2100 °C showed that the α-SiC becomes more dominant with increasing temperature in the Si-C-H-Cl system. While TMS was unsuitable for high temperature processing due to its high C/Si ratio, MTS was found to be appropriate for growing α-SiC crystals at high temperatures under a range of conditions. These results indicate that a novel method to grow α-SiC single crystals through HTCVD using MTS as a precursor could be established.

Elimination of carbon vacancies in 4H-SiC epi-layers by near-surface ion implantation: Influence of the ion species

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ayedh, H. M.; Svensson, B. G.; Hallén, A.

The carbon vacancy (V{sub C}) is a prevailing point defect in high-purity 4H-SiC epitaxial layers, and it plays a decisive role in controlling the charge carrier lifetime. One concept of reducing the V{sub C}-concentration is based on carbon self-ion implantation in a near surface layer followed by thermal annealing. This leads to injection of carbon interstitials (C{sub i}'s) and annihilation of V{sub C}'s in the epi-layer “bulk”. Here, we show that the excess of C atoms introduced by the self-ion implantation plays a negligible role in the V{sub C} annihilation. Actually, employing normalized implantation conditions with respect to displaced Cmore » atoms, other heavier ions like Al and Si are found to be more efficient in annihilating V{sub C}'s. Concentrations of V{sub C} below ∼2 × 10{sup 11} cm{sup −3} can be reached already after annealing at 1400 °C, as monitored by deep-level transient spectroscopy. This corresponds to a reduction in the V{sub C}-concentration by about a factor of 40 relative to the as-grown state of the epi-layers studied. The negligible role of the implanted species itself can be understood from simulation results showing that the concentration of displaced C atoms exceeds the concentration of implanted species by two to three orders of magnitude. The higher efficiency for Al and Si ions is attributed to the generation of collision cascades with a sufficiently high energy density to promote C{sub i}-clustering and reduce dynamic defect annealing. These C{sub i}-related clusters will subsequently dissolve during the post-implant annealing giving rise to enhanced C{sub i} injection. However, at annealing temperatures above 1500 °C, thermodynamic equilibrium conditions start to apply for the V{sub C}-concentration, which limit the net effect of the C{sub i} injection, and a competition between the two processes occurs.« less

High performance GaN-based LEDs on patterned sapphire substrate with patterned composite SiO2/Al2O3 passivation layers and TiO2/Al2O3 DBR backside reflector.

PubMed

Guo, Hao; Zhang, Xiong; Chen, Hongjun; Zhang, Peiyuan; Liu, Honggang; Chang, Hudong; Zhao, Wei; Liao, Qinghua; Cui, Yiping

2013-09-09

GaN-based light-emitting diodes (LEDs) on patterned sapphire substrate (PSS) with patterned composite SiO(2)/Al(2)O(3) passivation layers and TiO(2)/Al(2)O(3) distributed Bragg reflector (DBR) backside reflector have been proposed and fabricated. Highly passivated Al(2)O(3) layer deposited on indium tin oxide (ITO) layer with excellent uniformity and quality has been achieved with atomic layer deposition (ALD) technology. With a 60 mA current injection, an enhancement of 21.6%, 59.7%, and 63.4% in the light output power (LOP) at 460 nm wavelength was realized for the LED with the patterned composite SiO(2)/Al(2)O(3) passivation layers, the LED with the patterned composite SiO(2)/Al(2)O(3) passivation layers and Ag mirror + 3-pair TiO(2)/SiO(2) DBR backside reflector, and the LED with the patterned composite SiO(2)/Al(2)O(3) passivation layer and Ag mirror + 3-pair ALD-grown TiO(2)/Al(2)O(3) DBR backside reflector as compared with the conventional LED only with a single SiO(2) passivation layer, respectively.

Local matrix metalloproteinase 2 gene knockdown in balloon-injured rabbit carotid arteries using nonviral-small interfering RNA transfection.

PubMed

Hlawaty, Hanna; San Juan, Aurélie; Jacob, Marie-Paule; Vranckx, Roger; Letourneur, Didier; Feldman, Laurent J

2009-01-01

Small interfering RNA (siRNA) delivery is a promising approach for the treatment of cardiovascular diseases. Matrix metalloproteinase (MMP) 2 over-expression in the arterial wall has been implicated in restenosis after percutaneous coronary intervention, as well as in spontaneous atherosclerotic plaque rupture. We hypothesized that in vivo local delivery of siRNA targeted at MMP2 (MMP2-siRNA) in the balloon-injured carotid artery of hypercholesterolemic rabbits may lead to inhibition of MMP2 expression. Two weeks after balloon injury, 5 micromol/l of Tamra-tagged MMP2-siRNA, scramble siRNA or saline was locally injected in the carotid artery and incubated for 1 h. Fluorescent microscopy studies showed the circumferential uptake of siRNA in the superficial layers of neointimal cells. MMP2 mRNA levels, measured by the real-time reverse transcriptase-polymerase chain reaction, was decreased by 79 +/- 25% in MMP2-siRNA- versus scramble siRNA-transfected arteries (p < 0.05). MMP2 activity, measured by gelatin zymography performed on the conditioned media of MMP2-siRNA versus scramble siRNA transfected arteries, decreased by 53 +/- 29%, 50 +/- 24% and 46 +/- 14% at 24, 48 and 72 h, respectively (p < 0.005 for all). No effect was observed on MMP9, pro-MMP9 and TIMP-2 levels. The results obtained in the present study suggest that significant inhibition of gene expression can be achieved with local delivery of siRNA in the arterial wall in vivo. (c) 2008 John Wiley & Sons, Ltd.

PLGA microspheres encapsulating siRNA.

PubMed

De Rosa, Giuseppe; Salzano, Giuseppina

2015-01-01

The therapeutic use of small interfering RNA (siRNA) represents a new and powerful approach to suppress the expression of pathologically genes. However, biopharmaceutical drawbacks, such as short half-life, poor cellular uptake, and unspecific distribution into the body, hamper the development of siRNA-based therapeutics. Poly(lactide-co-glycolide), (PLGA) microspheres can be a useful tool to overcome these issues. siRNA can be encapsulated into the PLGA microspheres, which protects the loaded nucleic acid against the enzymatic degradation. Moreover, PLGA microspheres can be injected directly into the action site, where the siRNA can be released in controlled manner, thus avoiding the need of frequent invasive administrations. The complete biodegradability of PLGA to monomers easily metabolized by the body, and its approval by FDA and EMA for parenteral administration, assure the safety of this copolymer and do not require the removal of the device after the complete drug release. In chapter, a basic protocol for the preparation of PLGA microspheres encapsulating siRNA is described. This protocol is based on a double emulsion/solvent evaporation technique, a well known and easy to reproduce method. This specific protocol has been developed to encapsulate a siRNA anti-TNFα in PLGA microspheres, and it has been designed and optimized to achieve high siRNA encapsulation efficiency and slow siRNA release in vitro. However, it can be extended also to other siRNA as well as other RNA or DNA-based oligonucleotides (miRNA, antisense, decoy, etc.). Depending on the applications, chemical modifications of the backbone and site-specific modification within the siRNA sequences could be required.

Dark Current Characterization of SW HgCdTe IRFPAs Detectors on Si Substrate with Long Time Integration

NASA Astrophysics Data System (ADS)

Song, P. Y.; Ye, Z. H.; Huang, A. B.; Chen, H. L.; Hu, X. N.; Ding, R. J.; He, L.

2016-09-01

The dark currents of two short wave (SW) HgCdTe infrared focal plane arrays (IRFPA) detectors hybridized with direct injection (DI) readout and capacitance transimpedance amplifier (CTIA) with long time integration were investigated. The cutoff wavelength of the two SW IRFPAs is about 2.6 μm at 84 K. The dark current densities of DI and CTIA samples are approximately 8.0 × 10-12 A/cm2 and 7.2 × 10-10 A/cm2 at 110 K, respectively. The large divergence of the dark current density might arise from the injection efficiency difference of the two readouts. The low injection efficiency of the DI readout, compared with the high injection efficiency of the CTIA readout at low temperature, makes the dark current density of the DI sample much lower than that of the CTIA sample. The experimental value of injection efficiency of the DI sample was evaluated as 1.1% which is consistent with its theoretical value.

COMPARISON OF MERCURY CAPTURE EFFICIENCIES OF THREE DIFFERENT IN SITU GENERATED SORBENTS

EPA Science Inventory

Three different sorbent materials (Ti, Si and Ca based) were compared for their mercury capture efficiencies in an entrained flow reactor. Agglomerated particles with a high specific surface area were generated in situ by injecting gas phase sorbent precursors into a high tempera...

Analysis of Cyclic Variability of Heat Release for High-EGR GDI Engine Operation with Observations on Implications for Effective Control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaul, Brian C; Wagner, Robert M; Green Jr, Johney Boyd

2013-01-01

Operation of spark-ignition (SI) engines with high levels of charge dilution through exhaust gas recirculation (EGR) achieves significant engine efficiency gains while maintaining stoichiometric operation for compatibility with three-way catalysts. Dilution levels, however, are limited by cyclic variability-including significant numbers of misfires-that becomes more pronounced with increasing dilution. This variability has been shown to have both stochastic and deterministic components. Stochastic effects include turbulence, mixing variations, and the like, while the deterministic effect is primarily due to the nonlinear dependence of flame propagation rates and ignition characteristics on the charge composition, which is influenced by the composition of residual gasesmore » from prior cycles. The presence of determinism implies that an increased understanding the dynamics of such systems could lead to effective control approaches that allow operation near the edge of stability, effectively extending the dilution limit. This nonlinear dependence has been characterized previously for homogeneous charge, port fuel-injected (PFI) SI engines operating fuel-lean as well as with inert diluents such as bottled N2 gas. In this paper, cyclic dispersion in a modern boosted gasoline direct injection (GDI) engine using a cooled external EGR loop is examined, and the potential for improvement with effective control is evaluated through the use of symbol sequence statistics and other techniques from chaos theory. Observations related to the potential implications of these results for control approaches that could effectively enable engine operation at the edge of combustion stability are noted.« less

Non-equilibrium Green's functions method: Non-trivial and disordered leads

NASA Astrophysics Data System (ADS)

He, Yu; Wang, Yu; Klimeck, Gerhard; Kubis, Tillmann

2014-11-01

The non-equilibrium Green's function algorithm requires contact self-energies to model charge injection and extraction. All existing approaches assume infinitely periodic leads attached to a possibly quite complex device. This contradicts today's realistic devices in which contacts are spatially inhomogeneous, chemically disordered, and impacting the overall device characteristics. This work extends the complex absorbing potentials method for arbitrary, ideal, or non-ideal leads in atomistic tight binding representation. The algorithm is demonstrated on a Si nanowire with periodic leads, a graphene nanoribbon with trumpet shape leads, and devices with leads of randomly alloyed Si0.5Ge0.5. It is found that alloy randomness in the leads can reduce the predicted ON-state current of Si0.5Ge0.5 transistors by 45% compared to conventional lead methods.

Testing contamination source identification methods for water distribution networks

DOE PAGES

Seth, Arpan; Klise, Katherine A.; Siirola, John D.; ...

2016-04-01

In the event of contamination in a water distribution network (WDN), source identification (SI) methods that analyze sensor data can be used to identify the source location(s). Knowledge of the source location and characteristics are important to inform contamination control and cleanup operations. Various SI strategies that have been developed by researchers differ in their underlying assumptions and solution techniques. The following manuscript presents a systematic procedure for testing and evaluating SI methods. The performance of these SI methods is affected by various factors including the size of WDN model, measurement error, modeling error, time and number of contaminant injections,more » and time and number of measurements. This paper includes test cases that vary these factors and evaluates three SI methods on the basis of accuracy and specificity. The tests are used to review and compare these different SI methods, highlighting their strengths in handling various identification scenarios. These SI methods and a testing framework that includes the test cases and analysis tools presented in this paper have been integrated into EPA’s Water Security Toolkit (WST), a suite of software tools to help researchers and others in the water industry evaluate and plan various response strategies in case of a contamination incident. Lastly, a set of recommendations are made for users to consider when working with different categories of SI methods.« less

Effects of Silicon Amendment on Soilborne and Fruit Diseases of Avocado

PubMed Central

Dann, Elizabeth K.; Le, Duy P.

2017-01-01

The effects of silicon (Si) amendment have been studied in several plant/pathogen interactions; however, studies in horticultural tree crops are limited. Effects of amendment with soluble potassium silicate (AgSil®32, approximately 30% available Si), or milled cement building board by-products (Mineral Mulch (MM) or Mineral Dust (MD), containing 5% available Si) were investigated in field and greenhouse trials with avocado. Orchard soil drench applications with potassium silicate improved yield and quality of fruit, but visual health of trees declining from Phytophthora root rot (PRR) was not affected. Orchard spray or trunk injection applications with potassium silicate were ineffective. Amendment of potting mix with MM and MD reduced root necrosis of avocado seedlings after inoculation with Calonectria ilicicola, an aggressive soilborne pathogen causing black root rot. Application of MM to mature orchard trees declining with PRR had a beneficial effect on visual tree health, and Si accumulation in leaves and fruit peel, after only 10 months. Products that deliver available Si consistently for uptake are likely to be most successful in perennial tree crops. PMID:29053639

Temperature dependence of DC transport characteristics for a two-dimensional electron gas in an undoped Si/SiGe heterostructure

NASA Astrophysics Data System (ADS)

Chou, Kuan-Yu; Hsu, Nai-Wen; Su, Yi-Hsin; Chou, Chung-Tao; Chiu, Po-Yuan; Chuang, Yen; Li, Jiun-Yun

2018-02-01

We investigate DC characteristics of a two-dimensional electron gas (2DEG) in an undoped Si/SiGe heterostructure and its temperature dependence. An insulated-gate field-effect transistor was fabricated, and transfer characteristics were measured at 4 K-300 K. At low temperatures (T < 45 K), source electrons are injected into the buried 2DEG channel first and drain current increases with the gate voltage. By increasing the gate voltage further, the current saturates followed by a negative transconductance observed, which can be attributed to electron tunneling from the buried channel to the surface channel. Finally, the drain current is saturated again at large gate biases due to parallel conduction of buried and surface channels. By increasing the temperature, an abrupt increase in threshold voltage is observed at T ˜ 45 K and it is speculated that negatively charged impurities at the Al2O3/Si interface are responsible for the threshold voltage shift. At T > 45 K, the current saturation and negative transconductance disappear and the device acts as a normal transistor.

Evaluation of induced seismicity forecast models in the Induced Seismicity Test Bench

NASA Astrophysics Data System (ADS)

Király, Eszter; Gischig, Valentin; Zechar, Jeremy; Doetsch, Joseph; Karvounis, Dimitrios; Wiemer, Stefan

2016-04-01

Induced earthquakes often accompany fluid injection, and the seismic hazard they pose threatens various underground engineering projects. Models to monitor and control induced seismic hazard with traffic light systems should be probabilistic, forward-looking, and updated as new data arrive. Here, we propose an Induced Seismicity Test Bench to test and rank such models. We apply the test bench to data from the Basel 2006 and Soultz-sous-Forêts 2004 geothermal stimulation projects, and we assess forecasts from two models that incorporate a different mix of physical understanding and stochastic representation of the induced sequences: Shapiro in Space (SiS) and Hydraulics and Seismics (HySei). SiS is based on three pillars: the seismicity rate is computed with help of the seismogenic index and a simple exponential decay of the seismicity; the magnitude distribution follows the Gutenberg-Richter relation; and seismicity is distributed in space based on smoothing seismicity during the learning period with 3D Gaussian kernels. The HySei model describes seismicity triggered by pressure diffusion with irreversible permeability enhancement. Our results show that neither model is fully superior to the other. HySei forecasts the seismicity rate well, but is only mediocre at forecasting the spatial distribution. On the other hand, SiS forecasts the spatial distribution well but not the seismicity rate. The shut-in phase is a difficult moment for both models in both reservoirs: the models tend to underpredict the seismicity rate around, and shortly after, shut-in. Ensemble models that combine HySei's rate forecast with SiS's spatial forecast outperform each individual model.

Dynamic mode decomposition for plasma diagnostics and validation.

PubMed

Taylor, Roy; Kutz, J Nathan; Morgan, Kyle; Nelson, Brian A

2018-05-01

We demonstrate the application of the Dynamic Mode Decomposition (DMD) for the diagnostic analysis of the nonlinear dynamics of a magnetized plasma in resistive magnetohydrodynamics. The DMD method is an ideal spatio-temporal matrix decomposition that correlates spatial features of computational or experimental data while simultaneously associating the spatial activity with periodic temporal behavior. DMD can produce low-rank, reduced order surrogate models that can be used to reconstruct the state of the system with high fidelity. This allows for a reduction in the computational cost and, at the same time, accurate approximations of the problem, even if the data are sparsely sampled. We demonstrate the use of the method on both numerical and experimental data, showing that it is a successful mathematical architecture for characterizing the helicity injected torus with steady inductive (HIT-SI) magnetohydrodynamics. Importantly, the DMD produces interpretable, dominant mode structures, including a stationary mode consistent with our understanding of a HIT-SI spheromak accompanied by a pair of injector-driven modes. In combination, the 3-mode DMD model produces excellent dynamic reconstructions across the domain of analyzed data.

Dynamic mode decomposition for plasma diagnostics and validation

NASA Astrophysics Data System (ADS)

Taylor, Roy; Kutz, J. Nathan; Morgan, Kyle; Nelson, Brian A.

2018-05-01

We demonstrate the application of the Dynamic Mode Decomposition (DMD) for the diagnostic analysis of the nonlinear dynamics of a magnetized plasma in resistive magnetohydrodynamics. The DMD method is an ideal spatio-temporal matrix decomposition that correlates spatial features of computational or experimental data while simultaneously associating the spatial activity with periodic temporal behavior. DMD can produce low-rank, reduced order surrogate models that can be used to reconstruct the state of the system with high fidelity. This allows for a reduction in the computational cost and, at the same time, accurate approximations of the problem, even if the data are sparsely sampled. We demonstrate the use of the method on both numerical and experimental data, showing that it is a successful mathematical architecture for characterizing the helicity injected torus with steady inductive (HIT-SI) magnetohydrodynamics. Importantly, the DMD produces interpretable, dominant mode structures, including a stationary mode consistent with our understanding of a HIT-SI spheromak accompanied by a pair of injector-driven modes. In combination, the 3-mode DMD model produces excellent dynamic reconstructions across the domain of analyzed data.

Laser applications in meteorology and earth and atmospheric remote sensing; Proceedings of the Meeting, Los Angeles, CA, Jan. 16-18, 1989

NASA Technical Reports Server (NTRS)

Sokoloski, Martin M. (Editor)

1989-01-01

Various papers on laser applications in meteorology and earth and atmospheric remote sensing are presented. The individual topics addressed include: solid state lasers for the mid-IR region, tunable chromium lasers, GaInAsSb/AlGaAsSb injection lasers for remote sensing applications, development and design of an airborne autonomous wavemeter for laser tuning, fabrication of lightweight Si/SiC lidar mirrors, low-cost double heterostructure and quantum-well laser array development, nonlinear optical processes for the mid-IR region, simulated space-based Doppler lidar performance in regions of backscatter inhomogeneities, design of CO2 recombination catalysts for closed-cycle CO2 lasers, density measurements with combined Raman-Rayleigh lidar, geodynamics applications of spaceborne laser ranging, use of aircraft laser ranging data for forest mensuration, remote active spectrometer, multiwavelngth and triple CO2 lidars for trace gas detection, analysis of laser diagnostics in plumes, laser atmospheric wind sounder, compact Doppler lidar system using commercial off-the-shelf components, and preliminary design for a laser atmospheric wind sounder.

Improved understanding of the recombination rate at inverted p+ silicon surfaces

NASA Astrophysics Data System (ADS)

To, Alexander; Ma, Fajun; Hoex, Bram

2017-08-01

The effect of positive fixed charge on the recombination rate at SiN x -passivated p+ surfaces is studied in this work. It is shown that a high positive fixed charge on a low defect density, passivated doped surface can result in a near injection level independent lifetime in a certain injection level range. This behaviour is modelled with advanced computer simulations using Sentaurus TCAD, which replicates the measurements conditions during a photoconductance based effective minority carrier lifetime measurement. The resulting simulations show that the shape of the injection level dependent lifetime is a result of the surface recombination rate, which is non-linear due to the surfaces moving into inversion with increasing injection level. As a result, the surface recombination rate switches from being limited by electrons to holes. Equations describing the surface saturation current density, J 0s, during this regime are also derived in this work.

Demonstration of the spin solar cell and spin photodiode effect

PubMed Central

Endres, B.; Ciorga, M.; Schmid, M.; Utz, M.; Bougeard, D.; Weiss, D.; Bayreuther, G.; Back, C.H.

2013-01-01

Spin injection and extraction are at the core of semiconductor spintronics. Electrical injection is one method of choice for the creation of a sizeable spin polarization in a semiconductor, requiring especially tailored tunnel or Schottky barriers. Alternatively, optical orientation can be used to generate spins in semiconductors with significant spin-orbit interaction, if optical selection rules are obeyed, typically by using circularly polarized light at a well-defined wavelength. Here we introduce a novel concept for spin injection/extraction that combines the principle of a solar cell with the creation of spin accumulation. We demonstrate that efficient optical spin injection can be achieved with unpolarized light by illuminating a p-n junction where the p-type region consists of a ferromagnet. The discovered mechanism opens the window for the optical generation of a sizeable spin accumulation also in semiconductors without direct band gap such as Si or Ge. PMID:23820766

Generation and detection of dissipationless spin current in a MgO/Si bilayer

NASA Astrophysics Data System (ADS)

Lou, Paul C.; Kumar, Sandeep

2018-04-01

Spintronics is an analogue to electronics where the spin of the electron rather than its charge is functionally controlled for devices. The generation and detection of spin current without ferromagnetic or exotic/scarce materials are two of the biggest challenges for spintronics devices. In this study, we report a solution to the two problems of spin current generation and detection in Si. Using non-local measurement, we experimentally demonstrate the generation of helical dissipationless spin current using the spin-Hall effect. Contrary to the theoretical prediction, we observe the spin-Hall effect in both n-doped and p-doped Si. The helical spin current is attributed to the site-inversion asymmetry of the diamond cubic lattice of Si and structure inversion asymmetry in a MgO/Si bilayer. The spin to charge conversion in Si is insignificant due to weak spin-orbit coupling. For the efficient detection of spin current, we report spin to charge conversion at the MgO (1 nm)/Si (2 µm) (p-doped and n-doped) thin film interface due to Rashba spin-orbit coupling. We detected the spin current at a distance of  >100 µm, which is an order of magnitude larger than the longest spin diffusion length measured using spin injection techniques. The existence of spin current in Si is verified from the coercivity reduction in a Co/Pd multilayer due to spin-orbit torque generated by spin current from Si.

Demonstration of in-vivo Multi-Probe Tracker Based on a Si/CdTe Semiconductor Compton Camera

NASA Astrophysics Data System (ADS)

Takeda, Shin'ichiro; Odaka, Hirokazu; Ishikawa, Shin-nosuke; Watanabe, Shin; Aono, Hiroyuki; Takahashi, Tadayuki; Kanayama, Yousuke; Hiromura, Makoto; Enomoto, Shuichi

2012-02-01

By using a prototype Compton camera consisting of silicon (Si) and cadmium telluride (CdTe) semiconductor detectors, originally developed for the ASTRO-H satellite mission, an experiment involving imaging multiple radiopharmaceuticals injected into a living mouse was conducted to study its feasibility for medical imaging. The accumulation of both iodinated (131I) methylnorcholestenol and 85Sr into the mouse's organs was simultaneously imaged by the prototype. This result implies that the Compton camera is expected to become a multi-probe tracker available in nuclear medicine and small animal imaging.

Origin analysis of expanded stacking faults by applying forward current to 4H-SiC p-i-n diodes

NASA Astrophysics Data System (ADS)

Hayashi, Shohei; Naijo, Takanori; Yamashita, Tamotsu; Miyazato, Masaki; Ryo, Mina; Fujisawa, Hiroyuki; Miyajima, Masaaki; Senzaki, Junji; Kato, Tomohisa; Yonezawa, Yoshiyuki; Kojima, Kazutoshi; Okumura, Hajime

2017-08-01

Stacking faults expanded by the application of forward current to 4H-SiC p-i-n diodes were observed using a transmission electron microscope to investigate the expansion origin. It was experimentally confirmed that long-zonal-shaped stacking faults expanded from basal-plane dislocations converted into threading edge dislocations. In addition, stacking fault expansion clearly penetrated into the substrate to a greater depth than the dislocation conversion point. This downward expansion of stacking faults strongly depends on the degree of high-density minority carrier injection.

Net shape fabrication of Alpha Silicon Carbide turbine components

NASA Technical Reports Server (NTRS)

Storm, R. S.

1982-01-01

Development of Alpha Silicon Carbide components by net shape fabrication techniques has continued in conjunction with several turbine engine programs. Progress in injection molding of simple parts has been extended to much larger components. Turbine rotors fabricated by a one piece molding have been successfully spin tested above design speeds. Static components weighing up to 4.5 kg and 33 cc in diameter have also been produced using this technique. Use of sintering fixtures significantly improves dimensional control. A new Si-SiC composite material has also been developed with average strengths up to 1000 MPa (150 ksi) at 1200 C.

Si based GeSn light emitter: mid-infrared devices in Si photonics

NASA Astrophysics Data System (ADS)

Yu, S. Q.; Ghetmiri, S. A.; Du, W.; Margetis, J.; Zhou, Y.; Mosleh, A.; Al-Kabi, S.; Nazzal, A.; Sun, G.; Soref, R. A.; Tolle, J.; Li, B.; Naseem, H. A.

2015-02-01

Ge1-xSnx/Ge thin films and Ge/Ge1-xSnx/Ge n-i-p double heterostructure (DHS) have been grown using commercially available reduced pressure chemical vapor deposition (RPCVD) reactor. The Sn compositional material and optical characteristics have been investigated. A direct bandgap GeSn material has been identified with Sn composition of 10%. The GeSn DHS samples were fabricated into LED devices. Room temperature electroluminescence spectra were studied. A maximum emission power of 28mW was obtained with 10% Sn LED under the injection current density of 800 A/cm2.

Experimental insights into the geochemistry and mineralogy of a granite-hosted geothermal system injected with supercritical CO2

NASA Astrophysics Data System (ADS)

Lo Re, C.; Kaszuba, J. P.; Moore, J.; McPherson, B. J.

2011-12-01

Supercritical CO2 may be a viable working fluid in enhanced geothermal systems (EGS) due to its large expansivity, low viscosity, and reduced reactivity with rock as compared to water. Hydrothermal experiments are underway to evaluate the geochemical impact of using supercritical CO2 as a working fluid in granite-hosted geothermal systems. Synthetic aqueous fluid and a model granite are reacted at 250 °C and 250 bars in a rocking autoclave and Au-Ti reaction cell for a minimum of 28 days (water:rock ratio of approximately 20:1). Subsequent injection of supercritical CO2 increases pressure, which decays over time as the CO2 dissolves into the aqueous fluid. Initial experiments decreased to a steady state pressure of 450 bars approximately 14 hours after injection of supercritical CO2. Post-injection reaction is allowed to continue for at least an additional 28 days. Excess CO2 is injected to produce a separate supercritical fluid phase (between 1.7 and 3.1 molal), ensuring aqueous CO2 saturation for the duration of each experiment. The granite was created using mineral separates and consists of ground (75 wt%, <45 microns) and chipped (25 wt%, 0.5-1.0 cm), sub-equal portions of quartz, perthitic potassium feldspar (~ 25 wt% albite and 75 wt% potassium feldspar), oligoclase, and a minor (4 wt%) component of Fe-rich biotite. The synthetic saline water (I = 0.12 m) contains molal quantities of Na, Cl, and HCO3 and millimolal quantities of K, SiO2, SO4, Ca, Al, and Mg, in order of decreasing molality. Aqueous fluids are sampled approximately 10 times over the course of each experiment and analyzed for total dissolved carbon and sulfide by coulometric titration, anions by ion chromatography, and major, minor, and trace cations by ICP-OES and -MS. Bench pH measurements are paired with aqueous analyses to calculate in-situ pH. Solid reactants are evaluated by SEM-EDS, XRD, and/or bulk chemical analysis before and after each experiment. Analytical data are reviewed alongside geochemical models to evaluate fluid-rock interactions and the capacity of theoretical models to predict the observed outcome. Data derived from this study will inform our understanding of how a real world geothermal system may respond geochemically and mineralogically given 'spontaneous' injection of CO2, whether by an anthropogenic or natural source. Companion modeling work is also underway, which will use these experiments to calibrate EGS models for field application.

Chimeric Antisense Oligonucleotide Conjugated to α-Tocopherol

PubMed Central

Nishina, Tomoko; Numata, Junna; Nishina, Kazutaka; Yoshida-Tanaka, Kie; Nitta, Keiko; Piao, Wenying; Iwata, Rintaro; Ito, Shingo; Kuwahara, Hiroya; Wada, Takeshi; Mizusawa, Hidehiro; Yokota, Takanori

2015-01-01

We developed an efficient system for delivering short interfering RNA (siRNA) to the liver by using α-tocopherol conjugation. The α-tocopherol–conjugated siRNA was effective and safe for RNA interference–mediated gene silencing in vivo. In contrast, when the 13-mer LNA (locked nucleic acid)-DNA gapmer antisense oligonucleotide (ASO) was directly conjugated with α-tocopherol it showed markedly reduced silencing activity in mouse liver. Here, therefore, we tried to extend the 5′-end of the ASO sequence by using 5′-α-tocopherol–conjugated 4- to 7-mers of unlocked nucleic acid (UNA) as a “second wing.” Intravenous injection of mice with this α-tocopherol–conjugated chimeric ASO achieved more potent silencing than ASO alone in the liver, suggesting increased delivery of the ASO to the liver. Within the cells, the UNA wing was cleaved or degraded and α-tocopherol was released from the 13-mer gapmer ASO, resulting in activation of the gapmer. The α-tocopherol–conjugated chimeric ASO showed high efficacy, with hepatic tropism, and was effective and safe for gene silencing in vivo. We have thus identified a new, effective LNA-DNA gapmer structure in which drug delivery system (DDS) molecules are bound to ASO with UNA sequences. PMID:25584900

Efficient siRNA delivery system using carboxilated single-wall carbon nanotubes in cancer treatment.

PubMed

Neagoe, Ioana Berindan; Braicu, Cornelia; Matea, Cristian; Bele, Constantin; Florin, Graur; Gabriel, Katona; Veronica, Chedea; Irimie, Alexandru

2012-08-01

Several functionalized carbon nanotubes have been designed and tested for the purpose of nucleic acid delivery. In this study, the capacity of SWNTC-COOH for siRNA deliverey were investigated delivery in parallel with an efficient commercial system. Hep2G cells were reverse-transfected with 50 nM siRNA (p53 siRNA, TNF-alphasiRNA, VEGFsiRNA) using the siPORT NeoFX (Ambion) transfection agent in paralel with SWNTC-COOH, functionalised with siRNA. The highest level of gene inhibition was observed in the cases treated with p53 siRNA gene; in the case of transfection with siPort, the NeoFX value was 33.8%, while in the case of SWNTC-COOH as delivery system for p53 siRNA was 37.5%. The gene silencing capacity for VEGF was 53.7%, respectively for TNF-alpha 56.7% for siPORT NeoFX delivery systems versus 47.7% (VEGF) and 46.5% (TNF-alpha) for SWNTC-COOH delivery system. SWNTC-COOH we have been showed to have to be an efficient carrier system. The results from the inhibition of gene expresion for both transfection systems were confirmed at protein level. Overall, the lowest mRNA expression was confirmed at protein level, especially in the case of p53 siRNA and TNF-alpha siRNA transfection. Less efficient reduction protein expressions were observed in the case of VEGF siRNA, for both transfection systems at 24 h; only at 48 h, there was a statistically significant reduction of VEGF protein expression. SWCNT-COOH determined an efficient delivery of siRNA. SWNTC-COOH, combined with suitable tumor markers like p53 siRNA, TNFalpha siRNA or VEGF siRNA can be used for the efficient delivery of siRNA.

Ultrasound assisted gene and photodynamic synergistic therapy with multifunctional FOXA1-siRNA loaded porphyrin microbubbles for enhancing therapeutic efficacy for breast cancer.

PubMed

Zhao, Ranran; Liang, Xiaolong; Zhao, Bo; Chen, Min; Liu, Renfa; Sun, Sujuan; Yue, Xiuli; Wang, Shumin

2018-05-03

To improve the non-invasive therapeutic efficacy for ER positive breast cancer (ER+ BC), we fabricated a multifunctional FOXA1 loaded porphyrin microbubble to combine photodynamic therapy (PDT) and gene therapy of FOXA1 knockdown (KD) with ultrasound targeted microbubble destruction (UTMD) technology under the guidance of contrast enhanced ultrasound (CEUS). Cationic porphyrin microbubbles (CpMBs) were firstly fabricated from a porphyrin grafted lipid with two cationic amino groups (PGL-NH2) and fluorocarbon inert gas of C 3 F 8 . Porphyrin group in the CpMBs monolayer could be used as a photosensitizer for PDT, while amino groups could adsorb siRNA through electrostatic interaction for FOXA1 KD, which could inhibit the proliferation of estrogen-dependent ER+ BC. This system showed high photosensitizer and gene loading content. Moreover, CpMBs/siRNA can be converted into nanoparticles with low-frequency pulsed ultrasound (LFUS) exposure, which increase the transfection efficiency of siRNA (∼4 fold) and the porphyrin uptake (∼8 fold) in MCF-7 (a human breast cancer cell line, ER+) by sonoporation effect. In vivo, UTMD was performed under the guidance of CEUS, and the fluorescence intensity of CpMBs/siRNA at the tumour site reached a peak value at 6 h after injection and it was retained in the following 24 h. Furthermore, there was no tumour recurrence during the observation period (21 days) in the group of PDT combined with FXOA1 KD. Compared to the PDT or FOXA1 KD alone group, the combination of these two methods was much more efficient in inhibiting ER+ breast cancer, showing a good synergistic effect. CpMBs/siRNA combined with UTMD dramatically increased the local accumulation of porphyrin and siRNA through ultrasound-induced sonoporation effect under the guidance of CEUS, showing excellent therapeutic effect for estrogen-dependent ER+ breast cancer. Copyright © 2018 Elsevier Ltd. All rights reserved.

Hepatobiliary MRI: Signal intensity based assessment of liver function correlated to 13C-Methacetin breath test.

PubMed

Haimerl, Michael; Probst, Ute; Poelsterl, Stefanie; Beyer, Lukas; Fellner, Claudia; Selgrad, Michael; Hornung, Matthias; Stroszczynski, Christian; Wiggermann, Philipp

2018-06-13

Gadoxetic acid (Gd-EOB-DTPA) is a paramagnetic MRI contrast agent with raising popularity and has been used for evaluation of imaging-based liver function in recent years. In order to verify whether liver function as determined by real-time breath analysis using the intravenous administration of 13 C-methacetin can be estimated quantitatively from Gd-EOB-DTPA-enhanced MRI using signal intensity (SI) values. 110 patients underwent Gd-EOB-DTPA-enhanced 3-T MRI and, for the evaluation of liver function, a 13 C-methacetin breath test ( 13 C-MBT). SI values from before (SI pre ) and 20 min after (SI post ) contrast media injection were acquired by T1-weighted volume-interpolated breath-hold examination (VIBE) sequences with fat suppression. The relative enhancement (RE) between the plain and contrast-enhanced SI values was calculated and evaluated in a correlation analysis of 13 C-MBT values to SI post and RE to obtain a SI-based estimation of 13 C-MBT values. The simple regression model showed a log-linear correlation of 13 C-MBT values with SI post and RE (p < 0.001). Stratified by 3 different categories of 13 C-MBT readouts, there was a constant significant decrease in both SI post (p ≤ 0.002) and RE (p ≤ 0.033) with increasing liver disease progression as assessed by the 13 C-MBT. Liver function as determined using real-time 13 C-methacetin breath analysis can be estimated quantitatively from Gd-EOB-DTPA-enhanced MRI using SI-based indices.

PARALLEL PERTURBATION MODEL FOR CYCLE TO CYCLE VARIABILITY PPM4CCV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ameen, Muhsin Mohammed; Som, Sibendu

This code consists of a Fortran 90 implementation of the parallel perturbation model to compute cyclic variability in spark ignition (SI) engines. Cycle-to-cycle variability (CCV) is known to be detrimental to SI engine operation resulting in partial burn and knock, and result in an overall reduction in the reliability of the engine. Numerical prediction of cycle-to-cycle variability (CCV) in SI engines is extremely challenging for two key reasons: (i) high-fidelity methods such as large eddy simulation (LES) are required to accurately capture the in-cylinder turbulent flow field, and (ii) CCV is experienced over long timescales and hence the simulations needmore » to be performed for hundreds of consecutive cycles. In the new technique, the strategy is to perform multiple parallel simulations, each of which encompasses 2-3 cycles, by effectively perturbing the simulation parameters such as the initial and boundary conditions. The PPM4CCV code is a pre-processing code and can be coupled with any engine CFD code. PPM4CCV was coupled with Converge CFD code and a 10-time speedup was demonstrated over the conventional multi-cycle LES in predicting the CCV for a motored engine. Recently, the model is also being applied to fired engines including port fuel injected (PFI) and direct injection spark ignition engines and the preliminary results are very encouraging.« less

Effects of Cooling Rate on 6.5% Silicon Steel Ordering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cui, Jun; Macziewski, Chad; Jensen, Brandt

Increasing Si content improves magnetic and electrical properties of electrical steel, with 6.5% Si as the optimum. Unfortunately, when Si content approaches 5.7%, the Fe-Si alloy becomes brittle. At 6.5%, the steel conventional cold rolling process is no longer applicable. The heterogeneous formation of B2 and D03 ordered phases is responsible for the embrittlement. The formation of these ordered phases can be impeded by rapid cooling. However, only the cooling rates of water and brine water were investigated. A comprehensive study of the effect of rapid cooling rate on the formation of the ordered phases was carried out by varyingmore » wheel speed and melt-injection rate. Thermal imaging employed to measure cooling rates while microstructures of the obtained ribbons are characterized using X-ray diffraction and TEM. The electrical, magnetic and mechanical properties are characterized using 4-pt probe, VSM, and macro-indentation methods. The relations between physical properties and ordered phases are established.« less

Performance and emission characteristics of the thermal barrier coated SI engine by adding argon inert gas to intake mixture.

PubMed

Karthikeya Sharma, T

2015-11-01

Dilution of the intake air of the SI engine with the inert gases is one of the emission control techniques like exhaust gas recirculation, water injection into combustion chamber and cyclic variability, without scarifying power output and/or thermal efficiency (TE). This paper investigates the effects of using argon (Ar) gas to mitigate the spark ignition engine intake air to enhance the performance and cut down the emissions mainly nitrogen oxides. The input variables of this study include the compression ratio, stroke length, and engine speed and argon concentration. Output parameters like TE, volumetric efficiency, heat release rates, brake power, exhaust gas temperature and emissions of NOx, CO2 and CO were studied in a thermal barrier coated SI engine, under variable argon concentrations. Results of this study showed that the inclusion of Argon to the input air of the thermal barrier coated SI engine has significantly improved the emission characteristics and engine's performance within the range studied.

Monolithically integrated Si gate-controlled light-emitting device: science and properties

NASA Astrophysics Data System (ADS)

Xu, Kaikai

2018-02-01

The motivation of this study is to develop a p-n junction based light emitting device, in which the light emission is conventionally realized using reverse current driving, by voltage driving. By introducing an additional terminal of insulated gate for voltage driving, a novel three-terminal Si light emitting device is described where both the light intensity and spatial light pattern of the device are controlled by the gate voltage. The proposed light emitting device employs injection-enhanced Si in avalanche mode where electric field confinement occurs in the corner of a reverse-biased p+n junction. It is found that, depending on the bias conditions, the light intensity is either a linear or a quadratic function of the applied gate voltage or the reverse-bias. Since the light emission is based on the avalanching mode, the Si light emitting device offers the potential for very large scale integration-compatible light emitters for inter- or intra-chip signal transmission and contactless functional testing of wafers.

Performance and emission characteristics of the thermal barrier coated SI engine by adding argon inert gas to intake mixture

PubMed Central

Karthikeya Sharma, T.

2014-01-01

Dilution of the intake air of the SI engine with the inert gases is one of the emission control techniques like exhaust gas recirculation, water injection into combustion chamber and cyclic variability, without scarifying power output and/or thermal efficiency (TE). This paper investigates the effects of using argon (Ar) gas to mitigate the spark ignition engine intake air to enhance the performance and cut down the emissions mainly nitrogen oxides. The input variables of this study include the compression ratio, stroke length, and engine speed and argon concentration. Output parameters like TE, volumetric efficiency, heat release rates, brake power, exhaust gas temperature and emissions of NOx, CO2 and CO were studied in a thermal barrier coated SI engine, under variable argon concentrations. Results of this study showed that the inclusion of Argon to the input air of the thermal barrier coated SI engine has significantly improved the emission characteristics and engine’s performance within the range studied. PMID:26644918

Magnesium silicide nanoparticles as a deoxygenation agent for cancer starvation therapy

NASA Astrophysics Data System (ADS)

Zhang, Chen; Ni, Dalong; Liu, Yanyan; Yao, Heliang; Bu, Wenbo; Shi, Jianlin

2017-05-01

A material that rapidly absorbs molecular oxygen (known as an oxygen scavenger or deoxygenation agent (DOA)) has various industrial applications, such as in food preservation, anticorrosion of metal and coal deoxidation. Given that oxygen is vital to cancer growth, to starve tumours through the consumption of intratumoral oxygen is a potentially useful strategy in fighting cancer. Here we show that an injectable polymer-modified magnesium silicide (Mg2Si) nanoparticle can act as a DOA by scavenging oxygen in tumours and form by-products that block tumour capillaries from being reoxygenated. The nanoparticles are prepared by a self-propagating high-temperature synthesis strategy. In the acidic tumour microenvironment, the Mg2Si releases silane, which efficiently reacts with both tissue-dissolved and haemoglobin-bound oxygen to form silicon oxide (SiO2) aggregates. This in situ formation of SiO2 blocks the tumour blood capillaries and prevents tumours from receiving new supplies of oxygen and nutrients.

Magnesium silicide nanoparticles as a deoxygenation agent for cancer starvation therapy.

PubMed

Zhang, Chen; Ni, Dalong; Liu, Yanyan; Yao, Heliang; Bu, Wenbo; Shi, Jianlin

2017-05-01

A material that rapidly absorbs molecular oxygen (known as an oxygen scavenger or deoxygenation agent (DOA)) has various industrial applications, such as in food preservation, anticorrosion of metal and coal deoxidation. Given that oxygen is vital to cancer growth, to starve tumours through the consumption of intratumoral oxygen is a potentially useful strategy in fighting cancer. Here we show that an injectable polymer-modified magnesium silicide (Mg 2 Si) nanoparticle can act as a DOA by scavenging oxygen in tumours and form by-products that block tumour capillaries from being reoxygenated. The nanoparticles are prepared by a self-propagating high-temperature synthesis strategy. In the acidic tumour microenvironment, the Mg 2 Si releases silane, which efficiently reacts with both tissue-dissolved and haemoglobin-bound oxygen to form silicon oxide (SiO 2 ) aggregates. This in situ formation of SiO 2 blocks the tumour blood capillaries and prevents tumours from receiving new supplies of oxygen and nutrients.

Lateral power MOSFETs in silicon carbide

NASA Astrophysics Data System (ADS)

Spitz, Jan

2001-07-01

Because of its large bandgap, its high critical electric field, and its high quality native SiO2, silicon carbide is considered to be the material of choice for power switching electronics in the future. Until 1997 the maximum thickness of commercially available epilayers serving as the drift region for power devices has been limited to 10--15 mum, limiting the maximum blocking voltage to 1500 V for vertical power devices in silicon carbide. In this study, we present the first lateral power devices on a semi-insulating vanadium doped substrate of silicon carbide. The first generation of lateral DMOSFETs in 4H-SiC yielded a blocking voltage of 2.6 kV---more than twice what was previously reported for any SiC MOSFETs---but suffered from low MOS channel mobility caused by the high anneal temperatures (≥1600°C) required to activate the p-type ion-implant. Combining the high blocking-voltage of the vanadium-doped substrate with the higher MOS mobility previously achieved by an epitaxially-grown accumulation channel leads us to the LACCUFET device: No p-type implant is necessary. This device shows a blocking voltage of 2.7 kV unmatched by any SiC transistor until February 2000 combined with a much lower specific on-resistance of 3.6 O•cm2. The ability to combine long-channel test MOSFETs with high channel mobility of 27 cm2/(volt·sec) in 4H-SiC with power devices of 13 cm2/(volt·sec) on the same chip has been demonstrated. The Figure of Merit Vblock 2/Ron,sp for this new NON-RESURF LDMOSFET in 4H-SiC is close to the theoretical limit for vertical power devices made of silicon. The specific on-resistance can be reduced by factor 2.5 by forward-biasing the p-base to source junction by 2 to 3 volts. Basic operation in Static Induction Injection Accumulation FET (SIAFET) mode has been demonstrated. Lateral (Non-Punch-Through) Insulated Gate Bipolar Transistors (LIGBT) have been presented for the first time showing similar on-resistance and blocking voltages but significantly higher on-currents for both 4H and 6H-SiC devices compared to their MOSFET counterparts. Test p-i-n diodes show lower on-resistance by carrier injection into the drift region.

Metal-semiconductor interfacial reactions - Ni/Si system

NASA Technical Reports Server (NTRS)

Cheung, N. W.; Grunthaner, P. J.; Grunthaner, F. J.; Mayer, J. W.; Ullrich, B. M.

1981-01-01

X-ray photoelectron spectroscopy and channeling measurements with MeV He-4(+) ions have been used to probe the structure of the interface in the Ni/Si system. It is found that reactions occur where Ni is deposited on Si at 10 to the -10th torr: Si atoms are displaced from lattice sites, the Ni atoms are in an Si-rich environment, and the Ni/Si interface is graded in composition. Composition gradients are present at both interfaces in the Si/Ni2/Si/Ni system. For the Ni-Si system, cooling the substrate to 100 K slows down the reaction rate. The temperature dependence of the interfacial reactivity indicates the kinetic nature of metal-semiconductor interfaces.

Activation of IGF-1/IGFBP-3 signaling by berberine improves intestinal mucosal barrier of rats with acute endotoxemia.

PubMed

He, Yan; Yuan, Xiaoming; Zhou, Guangrong; Feng, Aiwen

2018-01-01

Insulin-like growth factor I (IGF-I) and binding protein 3 (IGFBP-3) play a role in the maintenance of gut mucosal barrier function. Nevertheless, IGF-I/IGFBP-3 and tight junction protein (TJP) expression in small intestinal mucosa are often impaired during endotoxemia. In this model of acute endotoxemia, the regulatory effect of berberine on IGF-I/IGFBP-3 and TJP expression in ileal mucosa was evaluated. The findings revealed systemic injection of lipopolysaccharide (LPS) suppressed mRNA and protein expression of IGF-I and IGFBP-3, but berberine ameliorated their production. LPS injection inhibited occludin and claudin-1 protein generation, and this inhibitory effect of LPS was abolished by berberine. Inhibition of IGF-I/IGFBP-3 signaling by AG1024 or siRNAs reduced berberine-induced occludin and claudin-1 production. Additionally, GW9662 was found to repress berberine-induced IGF-I/IGFBP-3 expression, indicating of a cross-link between PPARγ and IGF-I/IGFBP-3 axis. Copyright © 2017 Elsevier B.V. All rights reserved.

Improved silicon carbide for advanced heat engines

NASA Technical Reports Server (NTRS)

Whalen, Thomas J.; Mangels, J. A.

1986-01-01

The development of silicon carbide materials of high strength was initiated and components of complex shape and high reliability were formed. The approach was to adapt a beta-SiC powder and binder system to the injection molding process and to develop procedures and process parameters capable of providing a sintered silicon carbide material with improved properties. The initial effort was to characterize the baseline precursor materials, develop mixing and injection molding procedures for fabricating test bars, and characterize the properties of the sintered materials. Parallel studies of various mixing, dewaxing, and sintering procedures were performed in order to distinguish process routes for improving material properties. A total of 276 modulus-of-rupture (MOR) bars of the baseline material was molded, and 122 bars were fully processed to a sinter density of approximately 95 percent. Fluid mixing techniques were developed which significantly reduced flaw size and improved the strength of the material. Initial MOR tests indicated that strength of the fluid-mixed material exceeds the baseline property by more than 33 percent. the baseline property by more than 33 percent.

Three-dimensional and multienergy gamma-ray simultaneous imaging by using a Si/CdTe Compton camera.

PubMed

Suzuki, Yoshiyuki; Yamaguchi, Mitsutaka; Odaka, Hirokazu; Shimada, Hirofumi; Yoshida, Yukari; Torikai, Kota; Satoh, Takahiro; Arakawa, Kazuo; Kawachi, Naoki; Watanabe, Shigeki; Takeda, Shin'ichiro; Ishikawa, Shin-nosuke; Aono, Hiroyuki; Watanabe, Shin; Takahashi, Tadayuki; Nakano, Takashi

2013-06-01

To develop a silicon (Si) and cadmium telluride (CdTe) imaging Compton camera for biomedical application on the basis of technologies used for astrophysical observation and to test its capacity to perform three-dimensional (3D) imaging. All animal experiments were performed according to the Animal Care and Experimentation Committee (Gunma University, Maebashi, Japan). Flourine 18 fluorodeoxyglucose (FDG), iodine 131 ((131)I) methylnorcholestenol, and gallium 67 ((67)Ga) citrate, separately compacted into micro tubes, were inserted subcutaneously into a Wistar rat, and the distribution of the radioisotope compounds was determined with 3D imaging by using the Compton camera after the rat was sacrificed (ex vivo model). In a separate experiment, indium 111((111)In) chloride and (131)I-methylnorcholestenol were injected into a rat intravenously, and copper 64 ((64)Cu) chloride was administered into the stomach orally just before imaging. The isotope distributions were determined with 3D imaging after sacrifice by means of the list-mode-expectation-maximizing-maximum-likelihood method. The Si/CdTe Compton camera demonstrated its 3D multinuclear imaging capability by separating out the distributions of FDG, (131)I-methylnorcholestenol, and (67)Ga-citrate clearly in a test-tube-implanted ex vivo model. In the more physiologic model with tail vein injection prior to sacrifice, the distributions of (131)I-methylnorcholestenol and (64)Cu-chloride were demonstrated with 3D imaging, and the difference in distribution of the two isotopes was successfully imaged although the accumulation on the image of (111)In-chloride was difficult to visualize because of blurring at the low-energy region. The Si/CdTe Compton camera clearly resolved the distribution of multiple isotopes in 3D imaging and simultaneously in the ex vivo model.

Polyphosphoester nanoparticles as biodegradable platform for delivery of multiple drugs and siRNA

PubMed Central

Elzeny, Hadeel; Zhang, Fuwu; Ali, Esraa N; Fathi, Heba A; Zhang, Shiyi; Li, Richen; El-Mokhtar, Mohamed A; Hamad, Mostafa A; Wooley, Karen L; Elsabahy, Mahmoud

2017-01-01

Delivery of multiple therapeutics and/or diagnostic agents to diseased tissues is challenging and necessitates the development of multifunctional platforms. Among the various strategies for design of multifunctional nanocarriers, biodegradable polyphosphoester (PPE) polymers have been recently synthesized via a rapid and simple synthetic strategy. In addition, the chemical structure of the polymer could be tuned to form nanoparticles with varying surface chemistries and charges, which have shown exceptional safety and biocompatibility as compared to several commercial agents. The purpose of this study was to exploit a mixture of PPE nanoparticles of cationic and neutral surface charges for multiple delivery of anticancer drugs (ie, sorafenib and paclitaxel) and nucleic acids (ie, siRNA). Cationic PPE polymers could efficiently complex siRNA, and the stability of the nanoparticles could be maintained in physiological solutions and upon freeze-drying and were able to deliver siRNA in vivo when injected intravenously in mice. Commercially available cationic polyethylenimine polymer had LD50 of ca. 61.7 mg/kg in mice, whereas no animal died after injection of the cationic PPE polymer at a dose of >130 mg/kg. Neutral PPE nanoparticles were able to encapsulate two hydrophobic drugs, namely, sorafenib and paclitaxel, which are commonly used for the treatment of hepatocellular carcinoma. Mixing the neutral and cationic PPE nanoparticles did not result in any precipitation, and the size characteristics of both types of nanoparticles were maintained. Hence, PPE polymers might have potential for the delivery of multiple drugs and diagnostic agents to diseased tissues via simple synthesis of the individual polymers and assembly into nanoparticles that can host several drugs while being mixed in the same administration set, which is of importance for industrial and clinical development. PMID:28260861

Polyphosphoester nanoparticles as biodegradable platform for delivery of multiple drugs and siRNA.

PubMed

Elzeny, Hadeel; Zhang, Fuwu; Ali, Esraa N; Fathi, Heba A; Zhang, Shiyi; Li, Richen; El-Mokhtar, Mohamed A; Hamad, Mostafa A; Wooley, Karen L; Elsabahy, Mahmoud

2017-01-01

Delivery of multiple therapeutics and/or diagnostic agents to diseased tissues is challenging and necessitates the development of multifunctional platforms. Among the various strategies for design of multifunctional nanocarriers, biodegradable polyphosphoester (PPE) polymers have been recently synthesized via a rapid and simple synthetic strategy. In addition, the chemical structure of the polymer could be tuned to form nanoparticles with varying surface chemistries and charges, which have shown exceptional safety and biocompatibility as compared to several commercial agents. The purpose of this study was to exploit a mixture of PPE nanoparticles of cationic and neutral surface charges for multiple delivery of anticancer drugs (ie, sorafenib and paclitaxel) and nucleic acids (ie, siRNA). Cationic PPE polymers could efficiently complex siRNA, and the stability of the nanoparticles could be maintained in physiological solutions and upon freeze-drying and were able to deliver siRNA in vivo when injected intravenously in mice. Commercially available cationic polyethylenimine polymer had LD 50 of ca. 61.7 mg/kg in mice, whereas no animal died after injection of the cationic PPE polymer at a dose of >130 mg/kg. Neutral PPE nanoparticles were able to encapsulate two hydrophobic drugs, namely, sorafenib and paclitaxel, which are commonly used for the treatment of hepatocellular carcinoma. Mixing the neutral and cationic PPE nanoparticles did not result in any precipitation, and the size characteristics of both types of nanoparticles were maintained. Hence, PPE polymers might have potential for the delivery of multiple drugs and diagnostic agents to diseased tissues via simple synthesis of the individual polymers and assembly into nanoparticles that can host several drugs while being mixed in the same administration set, which is of importance for industrial and clinical development.

Neonatal alcohol exposure disrupts hippocampal neurogenesis and contextual fear conditioning in adult rats

PubMed Central

Hamilton, G.F.; Murawski, N.J.; St. Cyr, S.A.; Jablonski, S.A.; Schiffino, F.L.; Stanton, M.E.; Klintsova, A.Y.

2011-01-01

Developmental alcohol exposure can permanently alter brain structures and produce functional impairments in many aspects of behavior, including learning and memory. This study evaluates the effect of neonatal alcohol exposure on adult neurogenesis in the dentate gyrus of the hippocampus and the implications of such exposure for hippocampus-dependent contextual fear conditioning. Alcohol-exposed rats (AE) received 5.25 g/kg/day of alcohol on postnatal days (PD) 4-9 (third trimester in humans), in a binge-like manner. Two control groups were included: sham-intubated (SI) and suckle-control (SC). Animals were housed in social cages (3/cage) after weaning. On PD80, animals were injected with 200 mg/kg BrdU. Half of the animals were sacrificed two hours later. The remainder were sacrificed on PD114 to evaluate cell survival; separate AE, SI, and SC rats not injected with BrdU were tested for the context preexposure facilitation effect (CPFE; ∼PD117). There was no difference in the number of BrdU+ cells in AE, SI and SC groups on PD80. On PD114, cell survival was significantly decreased in AE rats, demonstrating that developmental alcohol exposure damages new cells' ability to incorporate into the network and survive. Behaviorally tested SC and SI groups preexposed to the training context 24h prior to receiving a 1.5mA 2s footshock froze significantly more during the context test than their counterparts preexposed to an alternate context. AE rats failed to show the CPFE. The current study shows the detrimental, long-lasting effects of developmental alcohol exposure on hippocampal adult neurogenesis and contextual fear conditioning. PMID:21816390

Monosilicide-disilicide-silicon phase equilibria in the nickel-platinum-silicon and nickel-palladium-silicon systems

NASA Astrophysics Data System (ADS)

Loomans, M. E.; Chi, D. Z.; Chua, S. J.

2004-10-01

Bulk-phase equilibria in Ni-rich/Si-rich alloys of the Ni-Pt-Si and Ni-Pd-Si systems were investigated. Results suggest that a bulk monosilicide solid solution, containing up to at least 11 at. pct Pt, exists in the Ni-Pt-Si system. Monosilicides containing more than 11 at. pct Pt were not examined. Results from both ternary systems point convincingly to the existence of a NiSi+Si↔NiSi2 eutectoid reaction near 700 °C in the Ni-Si binary system; data from the Ni-Pt-Si system, which yield the more accurate determination of the eutectoid temperature, place it at roughly 710 °C. The Pt and Pd concentrations of monosilicide in equilibrium with disilicide and Si were measured using energy-dispersive spectrometry (EDS) and were found to increase with temperature.

Improved silicon carbide for advanced heat engines. II - Pressureless sintering and mechanical properties of injection molded silicon carbide

NASA Technical Reports Server (NTRS)

Whalen, Thomas J.; Baer, J. R.

1989-01-01

The influence on density and strength of pressureless sintering in vacuum and argon environments has been evaluated with injection molded SiC materials. Main effects and two factor interactions of sintering (cycle variables temperature, time, heating rate, and atmosphere) were assessed. An improved understanding of the influence of the processing flaws and sintering conditions has been obtained. Strength and density have improved from a baseline level of 299 MPa (43.3 Ksi) and 94 pct of theoretical density to values greater than 483 MPa (70 Ksi) and 97 pct.

[Effect of S1PR2 inhibition on epithelial ovarian cancer SKOV3 cell proliferation in vitro and in vivo].

PubMed

Dai, L; Liu, Y X; Xie, L; Di, W

2018-02-25

Objective: To study the effect and mechanism of S1PR2 inhibition on epithelial ovarian cancer SKOV3 cell proliferation in vitro and in vivo. Methods: (1) A pair of S1PR2 gene small interference RNA (siRNA) , namely si-S1PR2, and a pair of negative control siRNA were designed. Western blot methods were used to detect the silence efficiency of the S1PR2 in the si-S1PR2 group, blank control group and negative control group. (2) Study in vitro: the experiment included three groups, namely si-S1PR2 group, blank control group and negative control group. Cell counting kit-8 (CCK-8) assay was used to detect the proliferation inhibition rates of the transfected cells. The cell cycles of the transfected cells were measured by flow cytometry. Western blot was used to detect the levels of phosph-extracellular regulated protein kinase 1/2 (p-ERK1/2) of the transfected cells. (3) Study in vivo:to establish intraperitoneal transplantation models, 8 mice in each group were intraperitoneally injected with 5×10(6) SKOV3 cells. Phosphate buffered saline (PBS) or JTE-013 were administered into mice twice per week starting on day 7 after the injection of the cancer cells. Twenty-eight days after nude mice intraperitoneal injection with JTE-013 or PBS, the mice were sacrificed and the number and the weight of visible tumors were calculated. Results: (1) The results of western blot showed that the relative S1PR2 protein expression levels were 0.24±0.04 in the si-S1PR2 group, which was lower than that in the blank control group (1.10±0.14, P< 0.01) and negative control group (1.07±0.13, P< 0.01) . (2) The results of CCK-8 assay indicated that after transfected for 24, 48 and 72 hours, the proliferation inhibition rate of si-S1PR2 group were respectively (26.6±3.3) %, (35.0±3.4) %, and (34.0±2.8) %, significantly lower than those in the blank control group (all 0; all P< 0.01) and negative control group [ (1.7±0.9) %, (2.5±0.5) %,and (2.4±1.1) % respectively; all P< 0.01]. The results of flow cytometry showed that the G(0)/G(1) ratio in the si-S1PR2 group [ (70.9±2.8) %] was significantly higher than those in the blank control group [ (61.7±2.4) %, P< 0.01] and negative control group [ (62.1±3.3) %, P< 0.01]. Western blot showed that the relative expression level of p-ERK1/2 in si-S1PR2 group (0.11±0.03) was significantly lower than those in the blank control group [ (0.62±0.09) , P< 0.01] and negative control group [ (0.68±0.09) , P< 0.01]. (3)Twenty-eight days after nude mice intraperitoneal injection with JTE-013 or PBS, the tumor number of the control group and JTE-013 group were respectively 15.4±4.3 and 8.2±3.7, the tumor weight were (0.45±0.12) and (0.21±0.07) g, respectively. The tumor number and weight in the JTE-013 group were significantly less than those in the control group (all P< 0.01) . Conclusions: The growth of ovarian cancer cells could be decreased by S1PR2 inhibition in vitro and in vivo. One of the mechanisms of the growth inhibitory effect is probably that S1PR2 inhibition lower the phosphorylation level of extracellular regulated protein kinase 1/2 (ERK1/2) pathway, which prevent the transformation of ovarian cancer cells from phase G(1) to S.

A peptide for targeted, systemic delivery of imaging and therapeutic compounds into acute brain injuries

NASA Astrophysics Data System (ADS)

Mann, Aman P.; Scodeller, Pablo; Hussain, Sazid; Joo, Jinmyoung; Kwon, Ester; Braun, Gary B.; Mölder, Tarmo; She, Zhi-Gang; Kotamraju, Venkata Ramana; Ranscht, Barbara; Krajewski, Stan; Teesalu, Tambet; Bhatia, Sangeeta; Sailor, Michael J.; Ruoslahti, Erkki

2016-06-01

Traumatic brain injury (TBI) is a major health and socio-economic problem, but no pharmacological agent is currently approved for the treatment of acute TBI. Thus, there is a great need for advances in this field. Here, we describe a short peptide (sequence CAQK) identified by in vivo phage display screening in mice with acute brain injury. The CAQK peptide selectively binds to injured mouse and human brain, and systemically injected CAQK specifically homes to sites of brain injury in mouse models. The CAQK target is a proteoglycan complex upregulated in brain injuries. Coupling to CAQK increased injury site accumulation of systemically administered molecules ranging from a drug-sized molecule to nanoparticles. CAQK-coated nanoparticles containing silencing oligonucleotides provided the first evidence of gene silencing in injured brain parenchyma by systemically administered siRNA. These findings present an effective targeting strategy for the delivery of therapeutics in clinical management of acute brain injuries.

A convenient method of manufacturing liquid-gated MoS2 field effect transistors

NASA Astrophysics Data System (ADS)

Lin, Kabin; Yuan, Zhishan; Yu, Yu; Li, Kun; Li, Zhongwu; Sha, Jingjie; Li, Tie; Chen, Yunfei

2017-10-01

In this paper, we present a simple and convenient method of manufacturing liquid-gated MoS2 field effect transistors (FETs). A Si3N4 chip is firstly fabricated by the semiconductor manufacturing process, then the mechanical exfoliation MoS2 is transferred onto the Si3N4 chip and is connected with the gold electrodes by depositing platinum to construct the MoS2 FETs. The liquid-gated is formed by injecting 0.1 M NaCl solution into reservoir to contact the back side of the Si3N4. Our measured results show that the contact properties between MoS2 and electrodes are in well condition and the liquid-gated MoS2 FETs have a high mobility that can reach up to 109 cm2 V-1 s-1.

Non-equilibrium Green's functions method: Non-trivial and disordered leads

DOE Office of Scientific and Technical Information (OSTI.GOV)

He, Yu, E-mail: heyuyhe@gmail.com; Wang, Yu; Klimeck, Gerhard

2014-11-24

The non-equilibrium Green's function algorithm requires contact self-energies to model charge injection and extraction. All existing approaches assume infinitely periodic leads attached to a possibly quite complex device. This contradicts today's realistic devices in which contacts are spatially inhomogeneous, chemically disordered, and impacting the overall device characteristics. This work extends the complex absorbing potentials method for arbitrary, ideal, or non-ideal leads in atomistic tight binding representation. The algorithm is demonstrated on a Si nanowire with periodic leads, a graphene nanoribbon with trumpet shape leads, and devices with leads of randomly alloyed Si{sub 0.5}Ge{sub 0.5}. It is found that alloy randomnessmore » in the leads can reduce the predicted ON-state current of Si{sub 0.5}Ge{sub 0.5} transistors by 45% compared to conventional lead methods.« less

A novel composite of SiO2-coated graphene oxide and molecularly imprinted polymers for electrochemical sensing dopamine.

PubMed

Zeng, Yanbo; Zhou, Ying; Kong, Lei; Zhou, Tianshu; Shi, Guoyue

2013-07-15

A novel imprinting route based on graphene oxide (GO) was proposed for preparing a composite of SiO2-coated GO and molecularly imprinted polymers (GO/SiO2-MIPs). In this route, SiO2-coated GO sheets were synthesized in a water-alcohol mixture with sol-gel technique. Prior to polymerization, the vinyl groups were introduced onto the surface of GO/SiO2 through chemical modification with γ-methacryloxypropyl trimethoxysilane (γ-MAPS), which can direct the selective polymerization on the GO/SiO2 surface. Then a novel composite of GO/SiO2-MIPs was successfully obtained by the copolymerization in presence of vinyl groups functionalized GO/SiO2, dopamine (DA), methacrylic acid and ethylene glycol dimethacrylate. The GO/SiO2-MIPs composite was characterized by FTIR, TGA, Raman spectroscopy, SEM and AFM. The properties such as special binding, adsorption dynamics and selective recognition ability using differential pulse voltammetry (DPV) were evaluated. The DPV current response of GO/SiO2-MIPs sensor was nearly 3.2 times that of the non-imprinted polymers (NIPs). In addition, the GO/SiO2-MIPs sensor could recognize DA from its relatively similar molecules of norepinephrine and epinephrine, while the sensors based on GO/SiO2-NIPs and vinyl groups functionalized GO/SiO2 did not have the ability. The GO/SiO2-MIPs sensor had a wide linear range over DA concentration from 5.0 × 10(-8) to 1.6 × 10(-4)M with a detection limit of 3.0 × 10(-8)M (S/N=3). The sensor based on this novel imprinted composite was applied to the determination of DA in injections and human urine samples with satisfactory results. Copyright © 2013 Elsevier B.V. All rights reserved.

Prediction of novel stable compounds in the Mg-Si-O system under exoplanet pressures

PubMed Central

Niu, Haiyang; Oganov, Artem R.; Chen, Xing-Qiu; Li, Dianzhong

2015-01-01

The Mg-Si-O system is the major Earth and rocky planet-forming system. Here, through quantum variable-composition evolutionary structure explorations, we have discovered several unexpected stable binary and ternary compounds in the Mg-Si-O system. Besides the well-known SiO2 phases, we have found two extraordinary silicon oxides, SiO3 and SiO, which become stable at pressures above 0.51 TPa and 1.89 TPa, respectively. In the Mg-O system, we have found one new compound, MgO3, which becomes stable at 0.89 TPa. We find that not only the (MgO)x·(SiO2)y compounds, but also two (MgO3)x·(SiO3)y compounds, MgSi3O12 and MgSiO6, have stability fields above 2.41 TPa and 2.95 TPa, respectively. The highly oxidized MgSi3O12 can form in deep mantles of mega-Earths with masses above 20 M⊕ (M⊕:Earth’s mass). Furthermore, the dissociation pathways of pPv-MgSiO3 are also clarified, and found to be different at low and high temperatures. The low-temperature pathway is MgSiO3 ⇒ Mg2SiO4 + MgSi2O5 ⇒ SiO2 + Mg2SiO4 ⇒ MgO + SiO2, while the high-temperature pathway is MgSiO3 ⇒ Mg2SiO4 + MgSi2O5 ⇒ MgO + MgSi2O5 ⇒ MgO + SiO2. Present results are relevant for models of the internal structure of giant exoplanets, and for understanding the high-pressure behavior of materials. PMID:26691903

Development of High Efficiency Clean Combustion Engine Designs for Spark-Ignition and Compression-Ignition Internal Combustion Engines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marriott, Craig; Gonzalez, Manual; Russell, Durrett

2011-06-30

This report summarizes activities related to the revised STATEMENT OF PROJECT OBJECTIVES (SOPO) dated June 2010 for the Development of High-Efficiency Clean Combustion engine Designs for Spark-Ignition and Compression-Ignition Internal Combustion Engines (COOPERATIVE AGREEMENT NUMBER DE-FC26-05NT42415) project. In both the spark- (SI) and compression-ignition (CI) development activities covered in this program, the goal was to develop potential production-viable internal combustion engine system technologies that both reduce fuel consumption and simultaneously met exhaust emission targets. To be production-viable, engine technologies were also evaluated to determine if they would meet customer expectations of refinement in terms of noise, vibration, performance, driveability, etc.more » in addition to having an attractive business case and value. Prior to this activity, only proprietary theoretical / laboratory knowledge existed on the combustion technologies explored The research reported here expands and develops this knowledge to determine series-production viability. Significant SI and CI engine development occurred during this program within General Motors, LLC over more than five years. In the SI program, several engines were designed and developed that used both a relatively simple multi-lift valve train system and a Fully Flexible Valve Actuation (FFVA) system to enable a Homogeneous Charge Compression Ignition (HCCI) combustion process. Many technical challenges, which were unknown at the start of this program, were identified and systematically resolved through analysis, test and development. This report documents the challenges and solutions for each SOPO deliverable. As a result of the project activities, the production viability of the developed clean combustion technologies has been determined. At this time, HCCI combustion for SI engines is not considered production-viable for several reasons. HCCI combustion is excessively sensitive to control variables such as internal dilution level and charge temperature. As a result, HCCI combustion has limited robustness when variables exceed the required narrow ranges determined in this program. HCCI combustion is also not available for the entire range of production engine speeds and loads, (i.e., the dynamic range is limited). Thus, regular SI combustion must be employed for a majority of the full dynamic range of the engine. This degrades the potential fuel economy impact of HCCI combustion. Currently-available combustion control actuators for the simple valve train system engine do not have the authority for continuous air - fuel or torque control for managing the combustion mode transitions between SI and HCCI and thus, require further refinement to meet customer refinement expectations. HCCI combustion control sensors require further development to enable robust long-term HCCI combustion control. Finally, the added technologies required to effectively manage HCCI combustion such as electric cam phasers, central direct fuel injection, cylinder pressure sensing, high-flow exhaust gas recirculation system, etc. add excessive on-engine cost and complexity that erodes the production-viability business« less

Nanosystems based on siRNA silencing HuR expression counteract diabetic retinopathy in rat.

PubMed

Amadio, Marialaura; Pascale, Alessia; Cupri, Sarha; Pignatello, Rosario; Osera, Cecilia; D Agata, Velia; D Amico, Agata Grazia; Leggio, Gian Marco; Ruozi, Barbara; Govoni, Stefano; Drago, Filippo; Bucolo, Claudio

2016-09-01

We evaluated whether specifically and directly targeting human antigen R (HuR), a member of embryonic lethal abnormal vision (ELAV) proteins family, may represent a new potential therapeutic strategy to manage diabetic retinopathy. Nanosystems loaded with siRNA silencing HuR expression (lipoplexes), consisting of solid lipid nanoparticles (SLN) and liposomes (SUV) were prepared. Photon correlation spectroscopy analysis, Zeta potential measurement and atomic force microscopy (AFM) studies were carried out to characterize the complexation of siRNA with the lipid nanocarriers. Nanosystems were evaluated by using AFM and scanning electron microscopy. The lipoplexes were injected into the eye of streptozotocin (STZ)-induced diabetic rats. Retinal HuR and VEGF levels were detected by Western blot and ELISA, respectively. Retinal histology was also carried out. The results demonstrated that retinal HuR and VEGF are significantly increased in STZ-rats and are blunted by HuR siRNA treatment. Lipoplexes with a weak positive surface charge and with a 4:1 N/P (cationic lipid nitrogen to siRNA phosphate) ratio exert a better transfection efficiency, significantly dumping retinal HuR and VEGF levels. In conclusion, we demonstrated that siRNA can be efficiently delivered into the rat retina using lipid-based nanocarriers, and some of the lipoplexes loaded with siRNA silencing HuR expression are potential candidates to manage retinal diseases. Copyright © 2016 Elsevier Ltd. All rights reserved.

The isothermal section of Gd-Ni-Si system at 1070 K

NASA Astrophysics Data System (ADS)

Morozkin, A. V.; Knotko, A. V.; Yapaskurt, V. O.; Manfrinetti, P.; Pani, M.; Provino, A.; Nirmala, R.; Quezado, S.; Malik, S. K.

2016-03-01

The Gd-Ni-Si system has been investigated at 1070 K by X-ray and microprobe analyses. The existence of the known compounds, i.e.: GdNi10Si2, GdNi8Si3, GdNi5Si3, GdNi7Si6, GdNi6Si6, GdNi4Si, GdNi2Si2, GdNiSi3, Gd3Ni6Si2, GdNiSi, GdNiSi2, GdNi0.4Si1.6, Gd2Ni2.35Si0.65, Gd3NiSi2, Gd3NiSi3 and Gd6Ni1.67Si3, has been confirmed. Moreover, five new phases have been identified in this system. The crystal structure for four of them has been determined: Gd2Ni16-12.8Si1-4.2 (Th2Zn17-type), GdNi6.6Si6 (GdNi7Si6-type), Gd3Ni8Si (Y3Co8Si-type) and Gd3Ni11.5Si4.2(Gd3Ru4Ga12-type). The compound with composition ~Gd2Ni4Si3 still remains with unknown structure. Quasi-binary phases, solid solutions, were detected at 1070 K to be formed by the binaries GdNi5, GdNi3, GdNi2, GdNi, GdSi2 and GdSi1.67; while no appreciable solubility was observed for the other binary compounds of the Gd-Ni-Si system. Magnetic properties of the GdNi6Si6, GdNi6.6Si6 and Gd3Ni11.5Si4.2 compounds have also been investigated and are here reported.

Enhanced extravasation, stability and in vivo cardiac gene silencing via in situ siRNA-albumin conjugation.

PubMed

Lau, Shannen; Graham, Bim; Cao, Nga; Boyd, Ben J; Pouton, Colin W; White, Paul J

2012-01-01

A potential barrier to progression of siRNA therapeutics to the clinic is the ability of these agents to cross the vascular endothelium to reach target cells. This study aimed to bypass the endothelial barrier by harnessing the extravasation capability of the serum protein albumin to allow siRNA to reach cardiomyocytes. A strategy for conjugating siRNA to albumin in vivo was developed that involved activating 3'-amine, 2'-O-methyl, phosphorothioate modified siRNA with succinimidyl 4-[N-maleimidomethyl]cyclohexane-1-carboxylate (SMCC) to yield maleimide-functionalized siRNA ("activated siRNA"); this thiol-reactive species can then irreversibly link to the single surface-exposed cysteine residue of endogenous albumin following intravenous administration. An IGF-I-receptor (IGF-IR) siRNA sequence which was effective in vitro was used to test the ability of the siRNA-albumin conjugate to bypass the endothelial barrier in Balb/C mice and produce silencing. In situ conjugation of maleimide-functionalized siRNA to albumin in mouse serum occurred within minutes of addition, and the resulting conjugate was found to be nuclease stable by SDS-PAGE analysis. In Sprague-Dawley rats, activated siRNA showed a significantly enhanced elimination half-life (75.9 ± 18.2 min) compared to unactivated siRNA (5.1 ± 0.2 min). Intravenous injection of this activated siRNA (1 mg/kg daily for four days) significantly reduced left ventricle IGF-IR mRNA to 64.1 ± 4.1% of that in vehicle-treated animals (mean ± SEM), while the control siRNA (unconjugated) had no effect (n = 4, P > 0.05). Imaging of microvessels from mice treated with fluorescein-labeled activated siRNA showed clear evidence of extravasation and cellular uptake in capillary endothelial cells, cardiomyocytes and vascular smooth muscle cells for mice treated with the activated siRNA but not mice treated with the unactivated siRNA. siRNA-albumin constructs are therefore capable of extravasation to the myocardium resulting in silencing in this otherwise silencing-resistant organ.

Stereotactic Administration of Edaravone Ameliorates Collagenase-Induced Intracerebral Hemorrhage in Rat.

PubMed

Zhang, Yan; Yang, Yang; Zhang, Guang-Zhu; Gao, Mou; Ge, Guang-Zhi; Wang, Qin-Qin; Ji, Xin-Chao; Sun, Yi-Lin; Zhang, Hong-Tian; Xu, Ru-Xiang

2016-10-01

Edaravone is widely used for treating ischemic stroke, but it is not still confirmed in intracerebral hemorrhage (ICH) as an ideal medication targeting the brain parenchyma. We aimed to investigate the neuroprotective effects of stereotactic administration of edaravone (SI) into the brain parenchyma. Intracerebral hemorrhage rat models were established by infusion of collagenase into the caudate nucleus. Neural functional recovery was assessed using modified neurological severity scores (mNSS). A comparative study of therapeutic effects between SI and intraperitoneal injection of edaravone (IP) involved in cerebral edema, blood-brain barrier (BBB) permeability, hematoma absorption, inflammatory response and neuronal apoptosis. Compared with IP, the mNSS was significantly (P < 0.05) improved by SI; cerebral edema and BBB permeability were dramatically ameliorated (P < 0.05); IL-4 and IL-10 levels increased, but IL-1β and TNF-α levels significantly decreased; neuron apoptosis decreased markedly (P < 0.05); and caspase-3 and Bax expression significantly dropped, but Bcl-2 increased in SI group (P < 0.05). SI markedly improved neurological deficits in ICH rat models via antiinflammatory and antiapoptosis mechanisms and promoted M2-type microglia differentiation. SI was effective in rats with collagenase-induced ICH. © 2016 The Authors. CNS Neuroscience & Therapeutics Published by John Wiley & Sons Ltd.

Perspective: The future of quantum dot photonic integrated circuits

NASA Astrophysics Data System (ADS)

Norman, Justin C.; Jung, Daehwan; Wan, Yating; Bowers, John E.

2018-03-01

Direct epitaxial integration of III-V materials on Si offers substantial manufacturing cost and scalability advantages over heterogeneous integration. The challenge is that epitaxial growth introduces high densities of crystalline defects that limit device performance and lifetime. Quantum dot lasers, amplifiers, modulators, and photodetectors epitaxially grown on Si are showing promise for achieving low-cost, scalable integration with silicon photonics. The unique electrical confinement properties of quantum dots provide reduced sensitivity to the crystalline defects that result from III-V/Si growth, while their unique gain dynamics show promise for improved performance and new functionalities relative to their quantum well counterparts in many devices. Clear advantages for using quantum dot active layers for lasers and amplifiers on and off Si have already been demonstrated, and results for quantum dot based photodetectors and modulators look promising. Laser performance on Si is improving rapidly with continuous-wave threshold currents below 1 mA, injection efficiencies of 87%, and output powers of 175 mW at 20 °C. 1500-h reliability tests at 35 °C showed an extrapolated mean-time-to-failure of more than ten million hours. This represents a significant stride toward efficient, scalable, and reliable III-V lasers on on-axis Si substrates for photonic integrate circuits that are fully compatible with complementary metal-oxide-semiconductor (CMOS) foundries.

Initial Microstructure Evaluation of a U3Si2 + W Fuel Pin Fabricated Via Arc Melt Gravity Drop Casting

NASA Astrophysics Data System (ADS)

Hoggan, Rita E.; Harp, Jason M.

2018-02-01

Injection casting has historically been used to fabricate metallic nuclear fuel on a large scale. Casting of intermetallic fuel forms, such as U3Si2, may be an alternative pathway for fabrication of fuel pins to powder metallurgy. To investigate casting on a small scale, arc melt gravity drop casting was employed to cast a one-off pin of U3Si2 for evaluation as a fabrication method for U3Si2 as a light water reactor fuel. The pin was sectioned and examined via optical microscopy and scanning electron microscopy equipped with energy dispersive x-ray spectroscopy (EDS). Image analysis was used to estimate the volume fraction of phase impurities as well as porosity. The primary phase determined by EDS was U3Si2 with U-O and U-Si-W phase impurities. Unusually high levels of tungsten were observed because of accidental tungsten introduction during arc melting. No significant changes in microstructure were observed after annealing a section of the pin at 800°C for 72 h. The average density of the sectioned specimens was 12.4 g/cm3 measured via Archimedes principle immersion density and He gas displacement.

Capillary electrophoresis method to determine siRNA complexation with cationic liposomes.

PubMed

Furst, Tania; Bettonville, Virginie; Farcas, Elena; Frere, Antoine; Lechanteur, Anna; Evrard, Brigitte; Fillet, Marianne; Piel, Géraldine; Servais, Anne-Catherine

2016-10-01

Small interfering RNA (siRNA) inducing gene silencing has great potential to treat many human diseases. To ensure effective siRNA delivery, it must be complexed with an appropriate vector, generally nanoparticles. The nanoparticulate complex requires an optimal physiochemical characterization and the complexation efficiency has to be precisely determined. The methods usually used to measure complexation in gel electrophoresis and RiboGreen ® fluorescence-based assay. However, those approaches are not automated and present some drawbacks such as the low throughput and the use of carcinogenic reagents. The aim of this study is to develop a new simple and fast method to accurately quantify the complexation efficiency. In this study, capillary electrophoresis (CE) was used to determine the siRNA complexation with cationic liposomes. The short-end injection mode applied enabled siRNA detection in less than 5 min. Moreover, the CE technique offers many advantages compared with the other classical methods. It is automated, does not require sample preparation and expensive reagents. Moreover, no mutagenic risk is associated with the CE approach since no carcinogenic product is used. Finally, this methodology can also be extended for the characterization of other types of nanoparticles encapsulating siRNA, such as cationic polymeric nanoparticles. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A concise way to estimate the average density of interface states in an ITO-SiOx/n-Si heterojunction solar cell

NASA Astrophysics Data System (ADS)

Li, Y.; Han, B. C.; Gao, M.; Wan, Y. Z.; Yang, J.; Du, H. W.; Ma, Z. Q.

2017-09-01

On the basis of a photon-assisted high frequency capacitance-voltage (C-V) method (1 MHz C-V), an effective approach is developed to evaluate the average interface state density (Dit) of an ITO-SiOx/n-Si heterojunction structure. Tin-doped indium oxide (ITO) films with different thicknesses were directly deposited on (100) n-type crystalline silicon by magnetron sputtering to fabricate semiconductor-insulator-semiconductor (SIS) hetero-interface regions where an ultra-thin SiOx passivation layer was naturally created. The morphology of the SiOx layer was confirmed by X-ray photoelectron spectroscopy depth profiling and transmission electron microscope analysis. The thinness of this SiOx layer was the main reason for the SIS interface state density being more difficult to detect than that of a typical metal-oxide-semiconductor structure. A light was used for photon injection while measuring the C-V of the device, thus enabling the photon-assisted C-V measurement of the Dit. By quantifying decreases of the light-induced-voltage as a variation of the capacitance caused by parasitic charge at interface states the passivation quality within the interface of ITO-SiOx/n-Si could be reasonably evaluated. The average interface state density of these SIS devices was measured as 1.2-1.7 × 1011 eV-1 cm-2 and declined as the passivation layer was made thicker. The lifetime of the minority carriers, dark leakage current, and the other photovoltaic parameters of the devices were also used to determine the passivation.

Epigenetic suppression of potassium-chloride co-transporter 2 expression in inflammatory pain induced by complete Freund's adjuvant (CFA).

PubMed

Lin, C-R; Cheng, J-K; Wu, C-H; Chen, K-H; Liu, C-K

2017-02-01

Multiple mechanisms contribute to the stimulus-evoked pain hypersensitivity that may be experienced after peripheral inflammation. Persistent pathological stimuli in many pain conditions affect the expression of certain genes through epigenetic alternations. The main purpose of our study was to investigate the role of epigenetic modification on potassium-chloride co-transporter 2 (KCC2) gene expression in the persistence of inflammatory pain. Persistent inflammatory pain was induced through the injection of complete Freund's adjuvant (CFA) in the left hind paw of rats. Acetyl-histone H3 and H4 level was determined by chromatin immunoprecipitation in the spinal dorsal horn. Pain behaviour and inhibitory synaptic function of spinal cord were determined before and after CFA injection. KCC2 expression was determined by real time RT-PCR and Western blot. Intrathecal KCC2 siRNA (2 μg per 10 μL per rat) or HDAC inhibitor (10 μg per 10 μL per rat) was injected once daily for 3 days before CFA injection. Persistent inflammatory pain epigenetically suppressed KCC2 expression through histone deacetylase (HDAC)-mediated histone hypoacetylation, resulting in decreased inhibitory signalling efficacy. KCC2 knock-down caused by intrathecal administration of KCC2 siRNA in naïve rats reduced KCC2 expression in the spinal cord, leading to sensitized pain behaviours and impaired inhibitory synaptic transmission in their spinal cords. Moreover, intrathecal HDAC inhibitor injection in CFA rats increased KCC2 expression, partially restoring the spinal inhibitory synaptic transmission and relieving the sensitized pain behaviour. These findings suggest that the transcription of spinal KCC2 is regulated by histone acetylation epigenetically following CFA. Persistent pain suppresses KCC2 expression through HDAC-mediated histone hypoacetylation and consequently impairs the inhibitory function of inhibitory interneurons. Drugs such as HDAC inhibitors that suppress the influences of persistent pain on the expression of KCC2 may serve as a novel analgesic. © 2016 European Pain Federation - EFIC®.

Kinetic limitations of the Mg(2)Si system for reversible hydrogen storage.

PubMed

Kelly, Stephen T; Van Atta, Sky L; Vajo, John J; Olson, Gregory L; Clemens, B M

2009-05-20

Despite the promising thermodynamics and storage capacities of many destabilized metal hydride hydrogen storage material systems, they are often kinetically limited from achieving practical and reversible behavior. Such is the case with the Mg2Si system. We investigated the kinetic mechanisms responsible for limiting the reversibility of the MgH2+Si system using thin films as a controlled research platform. We observed that the reaction MgH2 + 1/2Mg2Si + H2 is limited by the mass transport of Mg and Si into separate phases. Hydrogen readily diffuses through the Mg2Si material and nucleating MgH2 phase growth does not result in reaction completion. By depositing and characterizing multilayer films of Mg2Si and Mg with varying Mg2Si layer thicknesses, we conclude that the hydrogenation reaction consumes no more than 1 nm of Mg2Si, making this system impractical for reversible hydrogen storage.

Facet-embedded thin-film III-V edge-emitting lasers integrated with SU-8 waveguides on silicon.

PubMed

Palit, Sabarni; Kirch, Jeremy; Huang, Mengyuan; Mawst, Luke; Jokerst, Nan Marie

2010-10-15

A thin-film InGaAs/GaAs edge-emitting single-quantum-well laser has been integrated with a tapered multimode SU-8 waveguide onto an Si substrate. The SU-8 waveguide is passively aligned to the laser using mask-based photolithography, mimicking electrical interconnection in Si complementary metal-oxide semiconductor, and overlaps one facet of the thin-film laser for coupling power from the laser to the waveguide. Injected threshold current densities of 260A/cm(2) are measured with the reduced reflectivity of the embedded laser facet while improving single mode coupling efficiency, which is theoretically simulated to be 77%.

Final Report: Utilizing Alternative Fuel Ignition Properties to Improve SI and CI Engine Efficiency

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wooldridge, Margaret; Boehman, Andre; Lavoie, George

Experimental and modeling studies were completed to explore leveraging physical and chemical fuel properties for improved thermal efficiency of internal combustion engines. Fundamental studies of the ignition chemistry of ethanol and iso-octane blends and constant volume spray chamber studies of gasoline and diesel sprays supported the core research effort which used several reciprocating engine platforms. Single cylinder spark ignition (SI) engine studies were carried out to characterize the impact of ethanol/gasoline, syngas (H 2 and CO)/gasoline and other oxygenate/gasoline blends on engine performance. The results of the single-cylinder engine experiments and other data from the literature were used to trainmore » a GT Power model and to develop a knock criteria based on reaction chemistry. The models were used to interpret the experimental results and project future performance. Studies were also carried out using a state of the art, direct injection (DI) turbocharged multi- cylinder engine with piezo-actuated fuel injectors to demonstrate the promising spray and spark timing strategies from single-cylinder engine studies on the multi-cylinder engine. Key outcomes and conclusions of the studies were: 1. Efficiency benefits of ethanol and gasoline fuel blends were consistent and substantial (e.g. 5-8% absolute improvement in gross indicated thermal efficiency (GITE)). 2. The best ethanol/gasoline blend (based on maximum thermal efficiency) was determined by the engine hardware and limits based on component protection (e.g. peak in-cylinder pressure or maximum turbocharger inlet temperature) – and not by knock limits. Blends with <50% ethanol delivered significant thermal efficiency gains with conventional SI hardware while maintain good safety integrity to the engine hardware. 3. Other compositions of fuel blends including syngas (H 2 and CO) and other dilution strategies provided significant efficiency gains as well (e.g. 5% absolute improvement in ITE). 4. When the combination of engine and fuel system is not knock limited, multiple fuel injection events maintain thermal efficiency while improving engine-out emissions (e.g. CO, UHC, and particulate number).« less

The electroluminescence mechanism of Er³⁺ in different silicon oxide and silicon nitride environments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rebohle, L., E-mail: l.rebohle@hzdr.de; Wutzler, R.; Braun, M.

Rare earth doped metal-oxide-semiconductor (MOS) structures are of great interest for Si-based light emission. However, several physical limitations make it difficult to achieve the performance of light emitters based on compound semiconductors. To address this point, in this work the electroluminescence (EL) excitation and quenching mechanism of Er-implanted MOS structures with different designs of the dielectric stack are investigated. The devices usually consist of an injection layer made of SiO₂ and an Er-implanted layer made of SiO₂, Si-rich SiO₂, silicon nitride, or Si-rich silicon nitride. All structures implanted with Er show intense EL around 1540 nm with EL power efficienciesmore » in the order of 2 × 10⁻³ (for SiO₂:Er) or 2 × 10⁻⁴(all other matrices) for lower current densities. The EL is excited by the impact of hot electrons with an excitation cross section in the range of 0.5–1.5 × 10⁻¹⁵cm⁻². Whereas the fraction of potentially excitable Er ions in SiO₂ can reach values up to 50%, five times lower values were observed for other matrices. The decrease of the EL decay time for devices with Si-rich SiO₂ or Si nitride compared to SiO₂ as host matrix implies an increase of the number of defects adding additional non-radiative de-excitation paths for Er³⁺. For all investigated devices, EL quenching cross sections in the 10⁻²⁰ cm² range and charge-to-breakdown values in the range of 1–10 C cm⁻² were measured. For the present design with a SiO₂ acceleration layer, thickness reduction and the use of different host matrices did not improve the EL power efficiency or the operation lifetime, but strongly lowered the operation voltage needed to achieve intense EL.« less

Performance of CO2 enrich CNG in direct injection engine

NASA Astrophysics Data System (ADS)

Firmansyah, W. B.; Ayandotun, E. Z.; Zainal, A.; Aziz, A. R. A.; Heika, M. R.

2015-12-01

This paper investigates the potential of utilizing the undeveloped natural gas fields in Malaysia with high carbon dioxide (CO2) content ranging from 28% to 87%. For this experiment, various CO2 proportions by volume were added to pure natural gas as a way of simulating raw natural gas compositions in these fields. The experimental tests were carried out using a 4-stroke single cylinder spark ignition (SI) direct injection (DI) compressed natural gas (CNG) engine. The tests were carried out at 180° and 300° before top dead centre (BTDC) injection timing at 3000 rpm, to establish the effects on the engine performance. The results show that CO2 is suppressing the combustion of CNG while on the other hand CNG combustion is causing CO2 dissociation shown by decreasing CO2 emission with the increase in CO2 content. Results for 180° BTDC injection timing shows higher performance compared to 300° BTDC because of two possible reasons, higher volumetric efficiency and higher stratification level. The results also showed the possibility of increasing the CO2 content by injection strategy.

Imaging the photoinduced charge injection in CdS/TiO2 nanoparticles by the sequential fluorescence mapping method

NASA Astrophysics Data System (ADS)

Frederice, Rafael; Lencione, Diego; Gehlen, Marcelo H.

2017-03-01

The combination of a sensitizer and TiO2 nanoparticles forming a photocatalytic material is a central issue in many fields of applied photochemistry. The charge injection of emissive sensitizers into the conduction band of the semiconductor TiO2 may form a photoactive region that becomes dark, or it has a very low emission signal due to the generation of sensitizer radicals. However, by sequential coupling of a selected photoredox dye, such as resazurin, the dark region may become fluorescent at the interfaces where the charge injection has taken place due to the concomitant formation of fluorescent resorufin by cascade electron transfer. Using this strategy and a total internal reflection fluorescence microscopy (TIRFM) image, the charge injection in TiO2/CdS and SiO2/TiO2/CdS nanoparticles is investigated The method allows the charge injection efficiency of the excited CdS into TiO2 to be evaluated qualitatively, explaining the differences observed for these photocatalytic materials in H2 generation.

Imaging the photoinduced charge injection in CdS/TiO2 nanoparticles by the sequential fluorescence mapping method.

PubMed

Frederice, Rafael; Lencione, Diego; Gehlen, Marcelo H

2017-02-10

The combination of a sensitizer and TiO 2 nanoparticles forming a photocatalytic material is a central issue in many fields of applied photochemistry. The charge injection of emissive sensitizers into the conduction band of the semiconductor TiO 2 may form a photoactive region that becomes dark, or it has a very low emission signal due to the generation of sensitizer radicals. However, by sequential coupling of a selected photoredox dye, such as resazurin, the dark region may become fluorescent at the interfaces where the charge injection has taken place due to the concomitant formation of fluorescent resorufin by cascade electron transfer. Using this strategy and a total internal reflection fluorescence microscopy (TIRFM) image, the charge injection in TiO 2 /CdS and SiO 2 /TiO 2 /CdS nanoparticles is investigated The method allows the charge injection efficiency of the excited CdS into TiO 2 to be evaluated qualitatively, explaining the differences observed for these photocatalytic materials in H 2 generation.

Evidences of Multiple Magma Injections in Quaternary Balerang and Rajabasa Volcanoes, Indonesia

NASA Astrophysics Data System (ADS)

Hasibuan, R. F.; Ohba, T.; Abdurrachman, M.

2016-12-01

Quaternary Balerang and Rajabasa volcanoes are situated along the nearly north-south lineament with a most explosive Krakatau volcanic complex in the south and effusive Sukadana basalt plateau in the north. Some studies have elucidated that Krakatau volcano has multiple magma storage regions beneath together with evidences of magma mixing process. By considering these circumstances, it is necessary to know lateral variations of magmas and to characterize volcanic rocks from Rajabasa volcanic complex which is located between these distinct magmatic systems, in terms of magmatic processes and evolution. Methodologies we used are X-ray fluorescence to determine the whole rock chemistry, K-Ar isotope dating to determine the lifespan of the volcano, as well as EPMA analysis to obtain the chemical composition of minerals. The rock chemistry or TAS plot shows a linear trend, ranging from basaltic (51 wt.%) to rhyolitic (75 wt.%), indicating a chemical heterogeneity of magma. When SiO2 contents are correlated with the relative ages, we found a broad tendency that SiO2 contents progressively decrease with age. The Rajabasa volcano lifespan is known formed at 0.31 Ma while one of the youngest lava is identified erupted at 0.12 Ma. Some plagioclase crystals exhibit disequilibrium textures, like highly sieved core and clear rim regions, also overgrowth rim on the plagioclase and pyroxene crystals whose composition more primitive than the core's composition, indicating magmatic recharge events. Reverse zoning and resorption textures associated with compositional step zoning or progressive zoning are quite common as well in clinopyroxene and plagioclase crystals. By considering these evidences, we conclude that injection of a hotter basaltic magma into colder and more felsic magma occurred beneath the volcanoes.

Blue- and red-shifts of V2O5 phonons in NH3 environment by in situ Raman spectroscopy

NASA Astrophysics Data System (ADS)

Adeleke Akande, Amos; Machatine, Augusto Goncalo Jose; Masina, Bathusile; Chimowa, George; Matsoso, Boitumelo; Roro, Kittessa; Duvenhage, Mart-Mari; Swart, Hendrik; Bandyopadhyay, Jayita; Sinha Ray, Suprakas; Wakufwa Mwakikunga, Bonex

2018-01-01

A layer of ~30 nm V2O5/100 nm-SiO2 on Si was employed in the in situ Raman spectroscopy in the presence of NH3 effluent from a thermal decomposition of ammonium acetate salt with the salt heated at 100 °C. When the layer is placed at 25 °C, we observe a reversible red-shift of 194 cm-1 V2O5 phonon by 2 cm-1 upon NH3 gas injection to saturation, as well as a reversible blue-shift of the 996 cm-1 by 4 cm-1 upon NH3 injection. However when the sensing layer is placed at 100 °C, the 194 cm-1 remains un-shifted while the 996 cm-1 phonon is red-shifted. There is a decrease/increase in intensity of the 145 cm-1 phonon at 25 °C/100 °C when NH3 interacts with V2O5 surface. Using the traditional and quantitative gas sensor tester system, we find that the V2O5 sensor at 25 °C responds faster than at 100 °C up to 20 ppm of NH3 beyond which it responds faster at 100 °C than at 25 °C. Overall rankings of the NH3 gas sensing features between the two techniques showed that the in situ Raman spectroscopy is faster in response compared with the traditional chemi-resistive tester. Hooke’s law, phonon confinement in ~51 nm globular particles with ~20 nm pore size and physisorption/chemisorption principles have been employed in the explanation of the data presented.

High-Performance SiC/SiC Ceramic Composite Systems Developed for 1315 C (2400 F) Engine Components

NASA Technical Reports Server (NTRS)

DiCarlo, James A.; Yun, Hee Mann; Morscher, Gregory N.; Bhatt, Ramakrishna T.

2004-01-01

As structural materials for hot-section components in advanced aerospace and land-based gas turbine engines, silicon carbide (SiC) ceramic matrix composites reinforced by high performance SiC fibers offer a variety of performance advantages over current bill-of-materials, such as nickel-based superalloys. These advantages are based on the SiC/SiC composites displaying higher temperature capability for a given structural load, lower density (approximately 30- to 50-percent metal density), and lower thermal expansion. These properties should, in turn, result in many important engine benefits, such as reduced component cooling air requirements, simpler component design, reduced support structure weight, improved fuel efficiency, reduced emissions, higher blade frequencies, reduced blade clearances, and higher thrust. Under the NASA Ultra-Efficient Engine Technology (UEET) Project, much progress has been made at the NASA Glenn Research Center in identifying and optimizing two highperformance SiC/SiC composite systems. The table compares typical properties of oxide/oxide panels and SiC/SiC panels formed by the random stacking of balanced 0 degrees/90 degrees fabric pieces reinforced by the indicated fiber types. The Glenn SiC/SiC systems A and B (shaded area of the table) were reinforced by the Sylramic-iBN SiC fiber, which was produced at Glenn by thermal treatment of the commercial Sylramic SiC fiber (Dow Corning, Midland, MI; ref. 2). The treatment process (1) removes boron from the Sylramic fiber, thereby improving fiber creep, rupture, and oxidation resistance and (2) allows the boron to react with nitrogen to form a thin in situ grown BN coating on the fiber surface, thereby providing an oxidation-resistant buffer layer between contacting fibers in the fabric and the final composite. The fabric stacks for all SiC/SiC panels were provided to GE Power Systems Composites for chemical vapor infiltration of Glenn designed BN fiber coatings and conventional SiC matrices. Composite panels with system B were heat treated at Glenn, and the pores that remained open were filled by silicon melt infiltration (MI). Panels with system A and the other SiC/SiC systems were not heat treated, and remaining open pores in these systems were filled with SiC slurry and silicon MI.

SiNC: Saliency-injected neural codes for representation and efficient retrieval of medical radiographs

PubMed Central

Sajjad, Muhammad; Mehmood, Irfan; Baik, Sung Wook

2017-01-01

Medical image collections contain a wealth of information which can assist radiologists and medical experts in diagnosis and disease detection for making well-informed decisions. However, this objective can only be realized if efficient access is provided to semantically relevant cases from the ever-growing medical image repositories. In this paper, we present an efficient method for representing medical images by incorporating visual saliency and deep features obtained from a fine-tuned convolutional neural network (CNN) pre-trained on natural images. Saliency detector is employed to automatically identify regions of interest like tumors, fractures, and calcified spots in images prior to feature extraction. Neuronal activation features termed as neural codes from different CNN layers are comprehensively studied to identify most appropriate features for representing radiographs. This study revealed that neural codes from the last fully connected layer of the fine-tuned CNN are found to be the most suitable for representing medical images. The neural codes extracted from the entire image and salient part of the image are fused to obtain the saliency-injected neural codes (SiNC) descriptor which is used for indexing and retrieval. Finally, locality sensitive hashing techniques are applied on the SiNC descriptor to acquire short binary codes for allowing efficient retrieval in large scale image collections. Comprehensive experimental evaluations on the radiology images dataset reveal that the proposed framework achieves high retrieval accuracy and efficiency for scalable image retrieval applications and compares favorably with existing approaches. PMID:28771497

Predicting and monitoring response to chemotherapy by 1,3-bis(2-chloroethyl)-1-nitrosourea in subcutaneously implanted 9L glioma using the apparent diffusion coefficient of water and 23Na MRI.

PubMed

Babsky, Andriy M; Hekmatyar, S K; Zhang, Hong; Solomon, James L; Bansal, Navin

2006-07-01

To examine the effects of the alkylating anticancer drug 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) on (23)Na MRI and the water apparent diffusion coefficient (ADC) in subcutaneously- (sc-) implanted 9L glioma in rats. (23)Na MRI and (1)H water ADC measurements were performed on sham-treated control (N = 6) and BCNU-treated (N = 15) Fisher rats one day before BCNU injection and then one, three, and five days after BCNU injection. The BCNU-treated tumors were divided into BCNU-responsive (R(BCNU)) and BCNU-nonresponsive (NR(BCNU)) groups depending on the tumor volume changes that occurred after therapy. The pretreatment (23)Na MRI signal intensity (SI) and water ADC values were higher in R(BCNU) tumors compared to NR(BCNU) tumors. (23)Na MRI SI and water ADC increased with tumor growth in control and NR(BCNU) groups, but these changes were interrupted by BCNU therapy in R(BCNU) group. (23)Na MRI and water ADC measurements may be useful for predicting and monitoring response to chemotherapy in some tumors. However, the changes that occurred in (23)Na MRI SI and water ADC in sc-implanted 9L tumors are in contrast to previously published results for BCNU therapy of orthotopic 9L tumors. This may have important implications for monitoring therapy response in tumors. (c) 2006 Wiley-Liss, Inc.

A novel dual-valve sequential injection manifold (DV-SIA) for automated liquid-liquid extraction. Application for the determination of picric acid.

PubMed

Skrlíková, Jana; Andruch, Vasil; Sklenárová, Hana; Chocholous, Petr; Solich, Petr; Balogh, Ioseph S

2010-05-07

A novel dual-valve sequential injection system (DV-SIA) for online liquid-liquid extraction which resolves the main problems of LLE utilization in SIA has been designed. The main idea behind this new design was to construct an SIA system by connecting two independent units, one for aqueous-organic mixture flow and the second specifically for organic phase flow. As a result, the DV-SIA manifold consists of an Extraction unit and a Detection unit. Processing a mixture of aqueous-organic phase in the Extraction unit and a separated organic phase in the Detection unit solves the problems associated with the change of phases having different affinities to the walls of the Teflon tubing used in the SI-system. The developed manifold is a simple, user-friendly and universal system built entirely from commercially available components. The system can be used for a variety of samples and organic solvents and is simple enough to be easily handled by operators less familiar with flow systems. The efficiency of the DV-SIA system is demonstrated by the extraction of picric acid in the form of an ion associate with 2-[2-(4-methoxy-phenylamino)-vinyl]-1,3,3-trimethyl-3H-indolium reagent, with subsequent spectrophotometric detection. The suggested DV-SIA concept can be expected to stimulate new experiments in analytical laboratories and can be applied to the elaboration of procedures for the determination of other compounds extractable by organic solvents. It could thus form a basis for the design of simple, single-purpose commercial instruments used in LLE procedures. 2010 Elsevier B.V. All rights reserved.

Growth and optical properties of CMOS-compatible silicon nanowires for photonic devices

NASA Astrophysics Data System (ADS)

Guichard, Alex Richard

Silicon (Si) is the dominant semiconductor material in both the microelectronic and photovoltaic industries. Despite its poor optical properties, Si is simply too abundant and useful to be completely abandoned in either industry. Since the initial discovery of efficient room temperature photoluminescence (PL) from porous Si and the following discoveries of PL and time-resolved optical gain from Si nanocrystals (Si-nc) in SiO2, many groups have studied the feasibility of making Si-based, CMOS-compatible electroluminescent devices and electrically pumped lasers. These studies have shown that for Si-ne sizes below about 10 nm, PL can be attributed to radiative recombination of confined excitons and quantum efficiencies can reach 90%. PL peak energies are blue-shifted from the bulk Si band edge of 1.1 eV due to the quantum confinement effect and PL decay lifetimes are on mus timescales. However, many unanswered questions still exist about both the ease of carrier injection and various non-radiative and loss mechanisms that are present. A potential alternative material system to porous Si and Si-nc is Si nanowires (SiNWs). In this thesis, I examine the optical properties of SiNWs with diameters in the range of 3-30 nm fabricated by a number of compound metal oxide semiconductor (CMOS) compatible fabrication techniques including Chemical Vapor Deposition on metal nanoparticle coated substrates, catalytic wet etching of bulk Si and top-down electron-beam lithographic patterning. Using thermal oxidation and etching, we can increase the degree of confinement in the SiNWs. I demonstrate PL peaked in the visible and near-infrared (NIR) wavelength ranges that is tunable by controlling the crystalline SiNW core diameter, which is measured with dark field and high-resolution transmission electron microscopy. PL decay lifetimes of the SiNWs are on the order of 50 mus after proper surface passivation, which suggest that the PL is indeed from confined carriers in the SiNW cores. Investigation of the non-radiative Auger recombination (AR) process suggests that for high carrier densities in excess of 1019 cm-3, the AR lifetime is about 80 ns and decreases with increasing carrier density. This SiNW AR lifetime is slower than the AR process in Si nanocrystals at similar carrier densities, but faster than the radiative process. I also study the light emission and absorption properties of single SiNWs patterned on Silicon-on-insulator (SOI) substrates and find that a large fraction of NWs is optically dead. Moreover, the active, light-emitting nanostructures exhibit PL blinking, a mechanism often seen for individual nanostructure light emitters. These results are essential to evaluating Si nanostructures as a feasible gain or lasing medium. A second potential application for SiNWs is as a building block for low-cost, Si-based photovoltaics (PV). The market for thin-film PV, particularly organic thin-film PV, exists because it offers potential lower cost solutions for solar power versus bulk Si-based PV. However, many thin film technologies, while possessing superior optical absorption properties compared to Si, suffer from poor electronic transport properties. Here, I present a new Si-based PV design that combines the desirable optical properties of highly absorptive organic molecules and the high-mobility electronic properties of crystalline Si. This synergy is achieved by exploiting efficient Forster energy transfer from the light absorbing organic to SiNWs that enable current extraction. The energy transfer radius of a particular dye and bulk Si is found to be roughly 4 nm. Spectroscopic photocurrent experiments were performed on unpatterned SOI wafers as well as SiNWs patterned in SOI substrates and a significant photocurrent increase was seen in samples coated with organics versus uncoated samples. The photocurrent increase is seen in the wavelength range of the dye's absorption band, suggesting absorption of the dye and subsequent energy transfer to the Si plays a role. These results could pave the way for new low-cost, Si-based solar cell designs that leverage the strengths of the Si PV and microelectronics industries.

"My Mass is 20 kg": Aspects of Canadian and International Progress Toward an SI Way of Life.

ERIC Educational Resources Information Center

Allen, Harold Don

This speech, prepared for the SI Metric Conference "Metrication is Everybody's Business" held in Newark, Delaware, describes the extent to which the metric system (SI) has been adopted in Canada. The author provides examples of adoption of SI, mixture of SI with the English system, and areas where the English system is retained. He…

Development and Property Evaluation of Selected HfO2-Silicon and Rare Earth-Silicon Based Bond Coats and Environmental Barrier Coating Systems for SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2016-01-01

Ceramic environmental barrier coatings (EBC) and SiC/SiC ceramic matrix composites (CMCs) will play a crucial role in future aircraft propulsion systems because of their ability to significantly increase engine operating temperatures, improve component durability, reduce engine weight and cooling requirements. Advanced EBC systems for SiC/SiC CMC turbine and combustor hot section components are currently being developed to meet future turbine engine emission and performance goals. One of the significant material development challenges for the high temperature CMC components is to develop prime-reliant, high strength and high temperature capable environmental barrier coating bond coat systems, since the current silicon bond coat cannot meet the advanced EBC-CMC temperature and stability requirements. In this paper, advanced NASA HfO2-Si and rare earth Si based EBC bond coat EBC systems for SiC/SiC CMC combustor and turbine airfoil applications are investigated. High temperature properties of the advanced EBC systems, including the strength, fracture toughness, creep and oxidation resistance have been studied and summarized. The advanced NASA EBC systems showed some promise to achieve 1500C temperature capability, helping enable next generation turbine engines with significantly improved engine component temperature capability and durability.

Electrochemically assisted fabrication of size-exclusion films of organically modified silica and application to the voltammetry of phospholipids.

PubMed

Mehdi, B Layla; Rutkowska, Iwona A; Kulesza, Pawel J; Cox, James A

2013-06-01

Modification of electrodes with nm-scale organically modified silica films with pores diameters controlled at 10- and 50-nm is described. An oxidation catalyst, mixed-valence ruthenium oxide with cyano crosslinks or gold nanoparticles protected by dirhodium-substituted phosophomolybdate (AuNP-Rh 2 PMo 11 ), was immobilized in the pores. These systems comprise size-exclusion films at which the biological compounds, phosphatidylcholine and cardiolipin, were electrocatalytically oxidized without interference from surface-active concomitants such as bovine serum albumin. 10-nm pores were obtained by adding generation-4 poly(amidoamine) dendrimer, G4-PAMAM, to a (CH 3 ) 3 SiOCH 3 sol. 50-nm pores were obtained by modifying a glassy carbon electrode (GC) with a sub-monolayer film of aminopropyltriethoxylsilane, attaching 50-nm diameter poly(styrene sulfonate), PSS, spheres to the protonated amine, transferring this electrode to a (CH 3 ) 3 SiOCH 3 sol, and electrochemically generating hydronium at uncoated GC sites, which catalyzed ormosil growth around the PSS. Voltammetry of Fe(CN) 6 3- and Ru(NH 3 ) 6 3+ demonstrated the absence of residual charge after removal of the templating agents. With the 50-nm system, the pore structure was sufficiently defined to use layer-by-layer electrostatic assembly of AuNP-Rh 2 PMo 11 therein. Flow injection amperometry of phosphatidylcholine and cardiolipin demonstrated analytical utility of these electrodes.

High-Frequency Switching Transients and Power Loss Estimation in Electric Drive Systems that Utilize Wide-Bandgap Semiconductors

NASA Astrophysics Data System (ADS)

Fulani, Olatunji T.

Development of electric drive systems for transportation and industrial applications is rapidly seeing the use of wide-bandgap (WBG) based power semiconductor devices. These devices, such as SiC MOSFETs, enable high switching frequencies and are becoming the preferred choice in inverters because of their lower switching losses and higher allowable operating temperatures. Due to the much shorter turn-on and turn-off times and correspondingly larger output voltage edge rates, traditional models and methods previously used to estimate inverter and motor power losses, based upon a triangular power loss waveform, are no longer justifiable from a physical perspective. In this thesis, more appropriate models and a power loss calculation approach are described with the goal of more accurately estimating the power losses in WBG-based electric drive systems. Sine-triangle modulation with third harmonic injection is used to control the switching of the inverter. The motor and inverter models are implemented using Simulink and computer studies are shown illustrating the application of the new approach.

Remote plasma enhanced chemical deposition of non-crystalline GeO2 on Ge and Si substrates.

PubMed

Lucovsky, Gerald; Zeller, Daniel

2011-09-01

Non-crystalline GeO2 films remote were plasma deposited at 300 degrees C onto Ge substrates after a final rinse in NH4OH. The reactant precursors gas were: (i) down-stream injected 2% GeH4 in He as the Ge precursor, and (ii) up-stream, plasma excited O2-He mixtures as the O precursor. Films annealed at 400 degrees C displayed no evidence for loss of O resulting in Ge sub-oxide formation, and for a 5-6 eV mid-gap absorption associated with formation of GeOx suboxide bonding, x < 2. These films were stable in normal laboratory ambients with no evidence for reaction with atmospheric water. Films deposited on Ge and annealed at 600 degrees C and 700 degrees C display spectra indicative of loss of O-atoms, accompanied with a 5.5 eV absorption. X-ray absorption spectroscopy and many-electron theory are combined to describe symmetries and degeneracies for O-vacancy bonding defects. These include comparisons with remote plasma-deposited non-crystalline SiO2 on Si substrates with SiON interfacial layers. Three different properties of remote plasma GeO2 films are addressed comparisons between (i) conduction band and band edge states of GeO2 and SiO2, and (ii) electronic structure of O-atom vacancy defects in GeO2 and SiO2, and differences between (iii) annealing of GeO2 films on Ge substrates, and Si substrates passivated with SiON interfacial transition regions important for device applications.

Sub-barrier fusion of Si+Si systems

NASA Astrophysics Data System (ADS)

Colucci, G.; Montagnoli, G.; Stefanini, A. M.; Bourgin, D.; Čolović, P.; Corradi, L.; Courtin, S.; Faggian, M.; Fioretto, E.; Galtarossa, F.; Goasduff, A.; Haas, F.; Mazzocco, M.; Scarlassara, F.; Stefanini, C.; Strano, E.; Urbani, M.; Szilner, S.; Zhang, G. L.

2017-11-01

The near- and sub-barrier fusion excitation function has been measured for the system 30Si+30Si at the Laboratori Nazionali di Legnaro of INFN, using the 30Si beam of the XTU Tandem accelerator in the energy range 47 - 90 MeV. A set-up based on a beam electrostatic deflector was used for detecting fusion evaporation residues. The measured cross sections have been compared to previous data on 28Si+28Si and Coupled Channels (CC) calculations have been performed using M3Y+repulsion and Woods-Saxon potentials, where the lowlying 2+ and 3- excitations have been included. A weak imaginary potential was found to be necessary to reproduce the low energy 28Si+28Si data. This probably simulates the effect of the oblate deformation of this nucleus. On the contrary, 30Si is a spherical nucleus, 30Si+30Si is nicely fit by CC calculations and no imaginary potential is needed. For this system, no maximum shows up for the astrophysical S-factor so that we have no evidence for hindrance, as confirmed by the comparison with CC calculations. The logarithmic derivative of the two symmetric systems highlights their different low energy trend. A difference can also be noted in the two barrier distributions, where the high-energy peak present in 28Si+28Si is not observed for 30Si+30Si, probably due to the weaker couplings in last case.

Silicon Carbide MOSFET-Based Switching Power Amplifier for Precision Magnet Control

NASA Astrophysics Data System (ADS)

Miller, Kenneth; Ziemba, Timothy; Prager, James; Picard, Julian

2016-10-01

Eagle Harbor Technologies, Inc. (EHT) is using the latest in solid-state switching technologies to advance the state-of-the-art in magnet control for fusion science. Silicon carbide (SiC) MOSFETs offer advantages over IGBTs including lower drive energy requirements, lower conduction and switching losses, and higher switching frequency capabilities. When comparing SiC and traditional silicon-based MOSFETs, SiC MOSFETs provide higher current carrying capability allowing for smaller package weights and sizes and lower operating temperature. To validate the design, EHT has developed a low-power switching power amplifier (SPA), which has been used for precision control of magnetic fields, including rapidly changing the fields in coils. This design has been incorporated in to a high power SPA, which has been bench tested. This high power SPA will be tested at the Helicity Injected Torus (HIT) at the University of Washington. Following successful testing, EHT will produce enough SiC MOSFET-based SPAs to replace all of the units at HIT, which allows for higher frequency operation and an overall increase in pulsed current levels.

Dielectric properties of Ba0.6Sr0.4TiO3 thin films deposited by mist plasma evaporation using aqueous solution precursor

NASA Astrophysics Data System (ADS)

Huang, Hui; Shi, Peng; Wang, Minqiang; Yao, Xi; Tan, O. K.

2006-06-01

Mist plasma evaporation (MPE) technique has been developed to deposit Ba0.6Sr0.4TiO3 (BST) thin films on SiO2/Si and Pt/Ti/SiO2/Si substrates at atmospheric pressure using metal nitrate aqueous solution as precursor. MPE is characterized by the injection of liquid reactants into thermal plasma where the source materials in the droplets are evaporated by the high temperature of the thermal plasma. Nanometer-scale clusters are formed in the tail flame of the plasma, and then deposited and rearranged on the substrate at a lower temperature. Due to the high temperature annealing process of the thermal plasma before deposition, well-crystallized BST films were deposited at substrate temperature of 630 °C. The dielectric constant and dielectric loss of the film at 100 kHz are 715 and 0.24, respectively. Due to the good crystallinity of the BST films deposited by MPE, high dielectric tunability up to 39.3% is achieved at low applied electric field of 100 kV cm-1.

Focused electron beam induced deposition of pure SIO II

NASA Astrophysics Data System (ADS)

Perentes, Alexandre; Hoffmann, Patrik; Munnik, Frans

2007-02-01

Focused electron beam induced processing (FEBID) equipments are the "all in one" tools for high resolution investigation, and modification of nano-devices. Focused electron beam induced deposition from a gaseous precursor usually results in a nano-composite sub-structured material, in which the interesting material is embedded in an amorphous carbonaceous matrix. Using the Hydrogen free tetraisocyanatosilane Si(NCO) 4 molecule as Si source, we show how a controlled oxygen flux, simultaneously injected with the precursor vapors, causes contaminants to vanish from the FEB deposits obtained and leads to the deposition of pure SiO II. The chemical composition of the FEBID material could be controlled from SiC IINO 3 to SiO II, the latter containing undetectable foreign element contamination. The [O II] / [TICS] ratio needed to obtain SiO II in our FEB deposition equipment is larger than 300. The evolution of the FEBID material chemical composition is presented as function of the [O II] / [TICS] molecular flux ratios. A hypothetical decomposition pathway of this silane under these conditions is discussed based on the different species formed under electron bombardment of TICS. Transmission electron microscopy investigations demonstrated that the deposited oxide is smooth (roughness sub 2nm) and amorphous. Infrared spectroscopy confirmed the low concentration of hydroxyl groups. The Hydrogen content of the deposited oxide, measured by elastic recoil detection analysis, is as low as 1 at%. 193nm wavelength AIMS investigations of 125nm thick SiO II pads (obtained with [O II] / [TICS] = 325) showed an undetectable light absorption.

Improving the electrical properties of lanthanum silicate films on ge metal oxide semiconductor capacitors by adopting interfacial barrier and capping layers.

PubMed

Choi, Yu Jin; Lim, Hajin; Lee, Suhyeong; Suh, Sungin; Kim, Joon Rae; Jung, Hyung-Suk; Park, Sanghyun; Lee, Jong Ho; Kim, Seong Gyeong; Hwang, Cheol Seong; Kim, HyeongJoon

2014-05-28

The electrical properties of La-silicate films grown by atomic layer deposition (ALD) on Ge substrates with different film configurations, such as various Si concentrations, Al2O3 interfacial passivation layers, and SiO2 capping layers, were examined. La-silicate thin films were deposited using alternating injections of the La[N{Si(CH3)3}2]3 precursor with O3 as the La and O precursors, respectively, at a substrate temperature of 310 °C. The Si concentration in the La-silicate films was further controlled by adding ALD cycles of SiO2. For comparison, La2O3 films were also grown using [La((i)PrCp)3] and O3 as the La precursor and oxygen source, respectively, at the identical substrate temperature. The capacitance-voltage (C-V) hysteresis decreased with an increasing Si concentration in the La-silicate films, although the films showed a slight increase in the capacitance equivalent oxide thickness. The adoption of Al2O3 at the interface as a passivation layer resulted in lower C-V hysteresis and a low leakage current density. The C-V hysteresis voltages of the La-silicate films with Al2O3 passivation and SiO2 capping layers was significantly decreased to ∼0.1 V, whereas the single layer La-silicate film showed a hysteresis voltage as large as ∼1.0 V.

A Glu-urea-Lys Ligand-conjugated Lipid Nanoparticle/siRNA System Inhibits Androgen Receptor Expression In Vivo

PubMed Central

Lee, Justin B; Zhang, Kaixin; Tam, Yuen Yi C; Quick, Joslyn; Tam, Ying K; Lin, Paulo JC; Chen, Sam; Liu, Yan; Nair, Jayaprakash K; Zlatev, Ivan; Rajeev, Kallanthottathil G; Manoharan, Muthiah; Rennie, Paul S; Cullis, Pieter R

2016-01-01

The androgen receptor plays a critical role in the progression of prostate cancer. Here, we describe targeting the prostate-specific membrane antigen using a lipid nanoparticle formulation containing small interfering RNA designed to silence expression of the messenger RNA encoding the androgen receptor. Specifically, a Glu-urea-Lys PSMA-targeting ligand was incorporated into the lipid nanoparticle system formulated with a long alkyl chain polyethylene glycol-lipid to enhance accumulation at tumor sites and facilitate intracellular uptake into tumor cells following systemic administration. Through these features, and by using a structurally refined cationic lipid and an optimized small interfering RNA payload, a lipid nanoparticle system with improved potency and significant therapeutic potential against prostate cancer and potentially other solid tumors was developed. Decreases in serum prostate-specific antigen, tumor cellular proliferation, and androgen receptor levels were observed in a mouse xenograft model following intravenous injection. These results support the potential clinical utility of a prostate-specific membrane antigen–targeted lipid nanoparticle system to silence the androgen receptor in advanced prostate cancer. PMID:28131285

Solid solubility of Yb 2Si 2O 7 in β-, γ- and δ-Y 2Si 2O 7

NASA Astrophysics Data System (ADS)

Fernández-Carrión, A. J.; Alba, M. D.; Escudero, A.; Becerro, A. I.

2011-07-01

This paper examines the structural changes with temperature and composition in the Yb 2Si 2O 7-Y 2Si 2O 7 system; members of this system are expected to form in the intergranular region of Si 3N 4 and SiC structural ceramics when sintered with the aid of Yb 2O 3 and Y 2O 3 mixtures. A set of different compositions have been synthesised using the sol-gel method to obtain a xerogel, which has been calcined at temperatures between 1300 and 1650 °C during different times. Isotherms at 1300 and 1600 °C have been analysed in detail to evaluate the solid solubility of Yb 2Si 2O 7 in β-Y 2Si 2O 7 and γ-Y 2Si 2O 7. Although Yb 2Si 2O 7 shows a unique stable polymorph (β), Yb 3+ is able to replace Y 3+ in γ-Y 2Si 2O 7 and δ-Y 2Si 2O 7 at high temperatures and low Yb contents. IR results confirm the total solid solubility in the system and suggest a constant SiOSi angle of 180° in the Si 2O 7 unit across the system. The temperature-composition diagram of the system, obtained from powder XRD data, is dominated by the β- RE2Si 2O 7 polymorph, with γ- RE2Si 2O 7 and δ- RE2Si 2O 7 showing reduced stability fields. The diagram is in accordance with Felsche's diagram if average ionic radii are assumed for the members of the solid solution at any temperature, as long as the β-γ phase boundary is slightly shifted towards higher radii.

A methodology of SiP testing based on boundary scan

NASA Astrophysics Data System (ADS)

Qin, He; Quan, Haiyang; Han, Yifei; Zhu, Tianrui; Zheng, Tuo

2017-10-01

System in Package (SiP) play an important role in portable, aerospace and military electronic with the microminiaturization, light weight, high density, and high reliability. At present, SiP system test has encountered the problem on system complexity and malfunction location with the system scale exponentially increase. For SiP system, this paper proposed a testing methodology and testing process based on the boundary scan technology. Combining the character of SiP system and referencing the boundary scan theory of PCB circuit and embedded core test, the specific testing methodology and process has been proposed. The hardware requirement of the under test SiP system has been provided, and the hardware platform of the testing has been constructed. The testing methodology has the character of high test efficiency and accurate malfunction location.

Dy–Mn–Si as a representative of family of ‘Dy–Transition Metal–Si’ systems: Its isothermal sections, empirical rProd. Type: FTPules and new rare-earth manganese silicides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morozkin, A.V., E-mail: morozkin@general.chem.msu.ru; Knotko, A.V.; Yapaskurt, V.O.

2013-10-15

X-ray and microprobe analyses were employed for the investigation of Dy–Mn–Si system at 870/1070/1170 K. The Dy–Mn–Si system, contains the known DyMn{sub 2}Si{sub 2}, DyMnSi and Dy{sub 2}Mn{sub 3}Si{sub 5} compounds and DyMn{sub 4}Si{sub 2}, Dy{sub 2}MnSi{sub 2} and Dy{sub 3}Mn{sub 2}Si{sub 3} were new compounds identified first time and their structure are of the type TmCu{sub 4}Sb{sub 2}, Sc{sub 2}CoSi{sub 2} and Hf{sub 3}Ni{sub 2}Si{sub 3} respectively. The quasi-binary solid solutions were detected at 870/1070/1170 K: the ThMn{sub 12}-type Dy{sub 8}Mn{sub 87}Si{sub 5}, Th{sub 6}Mn{sub 23}-type Dy{sub 23}Mn{sub 72}Si{sub 5}, MgCu{sub 2}-type Dy{sub 33}Mn{sub 58}Si{sub 9} and AlB{sub 2}-typemore » Dy{sub 38}Mn{sub 2}Si{sub 58}. The other binary compounds of the Dy–Mn–Si system do not show any visible solubility. New phases R{sub 2}MnSi{sub 2} and R{sub 3}Mn{sub 2}Si{sub 3} (R=Gd, Tb, Ho–Tm) were found out and their structure of the type Sc{sub 2}CoSi{sub 2} and Hf{sub 3}Ni{sub 2}Si{sub 3} respectively. The specific features of ‘Dy–Transition Metal–Si’ systems were discussed. - Graphical abstract: The isothermal section of Dy–Mn–Si contains the known DyMn{sub 2}Si{sub 2}, DyMnSi, Dy{sub 2}Mn{sub 3}Si{sub 5} and new TmCu{sub 4}Sb{sub 2}-type DyMn{sub 4}Si{sub 2}, Sc{sub 2}CoSi{sub 2}-type Dy{sub 2}MnSi{sub 2} and Hf{sub 3}Ni{sub 2}Si{sub 3}-type Dy{sub 3}Mn{sub 2}Si{sub 3} ternary compounds. The ternary solid solution based on the binary compounds of the Dy–Mn and Dy–Si systems: the ThMn{sub 12}-type Dy{sub 8}Mn{sub 87}Si{sub 5}, Th{sub 6}Mn{sub 23}-type Dy{sub 23}Mn{sub 72}Si{sub 5}, MgCu{sub 2}-type Dy{sub 33}Mn{sub 58}Si{sub 9} and AlB{sub 2}-type Dy{sub 38}Mn{sub 2}Si{sub 58}. The other binary compounds of the Dy–Mn–Si system do not show any visible solubility. New Sc{sub 2}CoSi{sub 2}-type R{sub 2}MnSi{sub 2} and Hf{sub 3}Ni{sub 2}Si{sub 3}-type R{sub 3}Mn{sub 2}Si{sub 3} phases were discovered for R=Gd, Tb, Ho–Tm. Display Omitted - Highlights: • The Dy–Mn–Si section contains three known and three new ternary compounds (phases). • New phase the TmCu{sub 4}Sb{sub 2}-type DyMn{sub 4}Si{sub 2} compound. • New Sc{sub 2}CoSi{sub 2}-type R{sub 2}MnSi{sub 2} and Hf{sub 3}Ni{sub 2}Si{sub 3}-type R{sub 3}Mn{sub 2}Si{sub 3} were detected for R=Gd–Tm. • Dy–Mn–Si supplements the ‘Dy–3d metal–Si’ series and leads to the ‘RT{sub m}X{sub n}’ row's rule.« less

Ganaxolone improves behavioral deficits in a mouse model of post-traumatic stress disorder

PubMed Central

Pinna, Graziano; Rasmusson, Ann M.

2014-01-01

Allopregnanolone and its equipotent stereoisomer, pregnanolone (together termed ALLO), are neuroactive steroids that positively and allosterically modulate the action of gamma-amino-butyric acid (GABA) at GABAA receptors. Levels of ALLO are reduced in the cerebrospinal fluid of female premenopausal patients with post-traumatic stress disorder (PTSD), a severe, neuropsychiatric condition that affects millions, yet is without a consistently effective therapy. This suggests that restoring downregulated brain ALLO levels in PTSD may be beneficial. ALLO biosynthesis is also decreased in association with the emergence of PTSD-like behaviors in socially isolated (SI) mice. Similar to PTSD patients, SI mice also exhibit changes in the frontocortical and hippocampal expression of GABAA receptor subunits, resulting in resistance to benzodiazepine-mediated sedation and anxiolysis. ALLO acts at a larger spectrum of GABAA receptor subunits than benzodiazepines, and increasing corticolimbic ALLO levels in SI mice by injecting ALLO or stimulating ALLO biosynthesis with a selective brain steroidogenic stimulant, such as S-norfluoxetine, at doses far below those that block serotonin reuptake, reduces PTSD-like behavior in these mice. This suggests that synthetic analogs of ALLO, such as ganaxolone, may also improve anxiety, aggression, and other PTSD-like behaviors in the SI mouse model. Consistent with this hypothesis, ganaxolone (3.75–30 mg/kg, s.c.) injected 60 min before testing of SI mice, induced a dose-dependent reduction in aggression toward a same-sex intruder and anxiety-like behavior in an elevated plus maze. The EC50 dose of ganaxolone used in these tests also normalized exaggerated contextual fear conditioning and, remarkably, enhanced fear extinction retention in SI mice. At these doses, ganaxolone failed to change locomotion in an open field test. Therefore, unlike benzodiazepines, ganaxolone at non-sedating concentrations appears to improve dysfunctional emotional behavior associated with deficits in ALLO in mice and may provide an alternative treatment for PTSD patients with deficits in the synthesis of ALLO. Selective serotonin reuptake inhibitors (SSRIs) are the only medications currently approved by the FDA for treatment of PTSD, although they are ineffective in a substantial proportion of PTSD patients. Hence, an ALLO analog such as ganaxolone may offer a therapeutic GABAergic alternative to SSRIs for the treatment of PTSD or other disorders in which ALLO biosynthesis may be impaired. PMID:25309317

Local GABA receptor blockade reveals hindlimb responses in the SI forelimb-stump representation of neonatally amputated rats.

PubMed

Pluto, Charles P; Lane, Richard D; Rhoades, Robert W

2004-07-01

In adult rats that sustained forelimb amputation on the day of birth, there are numerous multi-unit recording sites in the forelimb-stump representation of primary somatosensory cortex (SI) that also respond to cutaneous stimulation of the hindlimb when cortical receptors for GABA are blocked. These normally suppressed hindlimb inputs originate in the SI hindlimb representation and synapse in the dysgranular cortex before exciting SI forelimb-stump neurons. In our previous studies, GABA (A + B) receptor blockade was achieved by topically applying a bicuculline methiodide/saclofen solution (BMI/SAC) to the cortical surface. This treatment blocks receptors throughout SI and does not allow determination of where along the above circuit the GABA-mediated suppression of hindlimb information occurs. In this study, focal injections of BMI/SAC were delivered to three distinct cortical regions that are involved in the hindlimb-to-forelimb-stump pathway. Blocking GABA receptors in the SI hindlimb representation and in the dysgranular cortex was largely ineffective in revealing hindlimb inputs ( approximately 10% of hindlimb inputs were revealed in both cases). In contrast, when the blockade was targeted at forelimb-stump recording sites, >80% of hindlimb inputs were revealed. Thus GABAergic interneurons within the forelimb-stump representation suppress the expression of reorganized hindlimb inputs to the region. A circuit model incorporating these and previous observations is presented and discussed.

Application of 23Na MRI to Monitor Chemotherapeutic Response in RIF-1 Tumors1

PubMed Central

Babsky, Andriy M; Hekmatyar, Shahryar K; Zhang, Hong; Solomon, James L; Bansal, Navin

2005-01-01

Abstract Effects of an alkylating anticancer drug, cyclophosphamide (Cp), on 23Na signal intensity (23Na SI) and water apparent diffusion coefficient (ADC) were examined in subcutaneously-implanted radiation-induced fibrosarcoma (RIF-1) tumors by in vivo 23Na and 1H magnetic resonance imaging (MRI). MRI experiments were performed on untreated control (n = 5) and Cp-treated (n = 6) C3H mice, once before Cp injection (300 mg/kg) then daily for 3 days after treatment. Tumor volumes were significantly lower in treated animals 2 and 3 days posttreatment. At the same time points, MRI experiments showed an increase in both 23Na SI and water ADC in treated tumors, whereas control tumors did not show any significant changes. The correlation between 23Na SI and water ADC changes was dramatically increased in the Cp-treated group, suggesting that the observed increases in 23Na SI and water ADC were caused by the same mechanism. Histologic sections showed decreased cell density in the regions of increased 23Na and water ADC SI. Destructive chemical analysis showed that Cp treatment increased the relative extracellular space and tumor [Na+]. We conclude that the changes in water ADC and 23Na SI were largely due to an increase in extracellular space. 23Na MRI and 1H water ADC measurements may provide valuable noninvasive techniques for monitoring chemotherapeutic responses. PMID:16026645

Critical thickness of transition from 2D to 3D growth and peculiarities of quantum dots formation in GexSi1-x/Sn/Si and Ge1-ySny/Si systems

NASA Astrophysics Data System (ADS)

Lozovoy, Kirill A.; Kokhanenko, Andrey P.; Voitsekhovskii, Alexander V.

2018-03-01

Nowadays using of tin as one of the deposited materials in GeSi/Sn/Si, GeSn/Si and GeSiSn/Si material systems is one of the most topical problems. These materials are very promising for various applications in nanoelectronics and optoelectronics due to possibility of band gap management and synthesis of direct band semiconductors within these systems. However, there is a lack of theoretical investigations devoted to the peculiarities of germanium on silicon growth in the presence of tin. In this paper a new theoretical approach for modeling growth processes of binary and ternary semiconductor compounds during the molecular beam epitaxy in these systems is presented. The established kinetic model based on the general nucleation theory takes into account the change in physical and mechanical parameters, diffusion coefficient and surface energies in the presence of tin. With the help of the developed model the experimentally observed significant decrease in the 2D-3D transition temperatures for GeSiSn/Si system compared to GeSi/Si system is theoretically explained for the first time in the literature. Besides that, the derived expressions allow one to explain the experimentally observed temperature dependencies of the critical thickness, as well as to predict the average size and surface density of quantum dots for different contents and temperatures in growth experiment, that confirms applicability of the model proposed. Moreover, the established model can be easily applied to other material systems in which the Stranski-Krastanow growth mode occurs.

Development of a model and computer code to describe solar grade silicon production processes. [phase changes in chemical reactors

NASA Technical Reports Server (NTRS)

Gould, R. K.

1978-01-01

Mechanisms for the SiCl4/Na and SiF4/Na reaction systems were examined. Reaction schemes which include 25 elementary reactions were formulated for each system and run to test the sensitivity of the computed concentration and temperature profiles to the values given estimated rate coefficients. It was found that, for SiCl4/Na, the rate of production of free Si is largely mixing-limited for reasonable rate coefficient estimates. For the SiF4/Na system the results indicate that the endothermicities of many of the reactions involved in producing Si from SiF4/Na cause this system to be chemistry-limited rather than mixing-limited.

Assessment of calcium addition on the removal of U(VI) in the alkaline conditions created by NH 3 gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katsenovich, Yelena; Cardona, Claudia; Szecsody, Jim

Remediation of uranium (U) contamination in the deep vadose zone (VZ) sediments abundant in calcite mineral is a challenging task considering the formation of highly stable and mobile uranyl complexes with carbonate and calcium in pore water composition. There is a concern that uranium contamination in the VZ can serve as a continued source for groundwater pollution, creating a risk to human health and the environment through the groundwater pathway. This requires in-situ remediation of the radionuclide-contaminated VZ to convert soluble U species to low solubility precipitates that are stable in the natural environment. Injection of reactive gasses (e.g., NHmore » 3) is a promising technology to decrease U mobility in the unsaturated zone without the addition of liquid amendments. The NH 3 injection creates alkaline conditions that can alter the sediment pore water composition due to a release of elements from minerals (via desorption and dissolution) that are present in the sediment. However, it is not known how VZ pore water constituents (Si, Al 3+, HCO 3 -, and Ca 2 +) would affect U(VI) removal/precipitation in alkaline conditions. This study quantified the role of major pore water constituents typically present in the arid and semi-arid environments of the western regions of the U.S and identified solid uranium-bearing phases that could potentially precipitate from solutions approximating pore water compositions after pH manipulations via ammonia gas injections. Triplicate samples were prepared using six Si (5, 50 100, 150, 200, and 250 mM), six HCO 3 - (0, 3, 25, 50, 75, and 100 mM), and two Ca 2+ (5 and 10 mM) concentrations. The concentration of aluminum and uranium was kept constant at 5 mM and 0.0084 mM, respectively, in all synthetic formulations tested. Results showed that the percentage of U(VI) removal was controlled by the Si/Al molar ratios and Ca 2+ concentrations. Regardless of the bicarbonate concentration tested, the percentage of U(VI) removed increased as the Si/Al ratios were increased. However, higher Ca concentrations correlated with higher U(VI) removal, ranging between 96% and 99%, at low Si/Al ratios. The SEM images of dried precipitates displayed dense amorphous regions high in silica content, where EDS elemental analysis unveiled higher U atomic percentages. The formation of uranyl silicate and carbonate minerals was also predicted by the speciation modeling. XRD analysis revealed the presence of uranyl carbonate mineral phases (andersonite, grimselite); however, uranyl silicates predicted (Na-boltwoodite) were not identified experimentally, possibly due to the amorphous nature of the silica solid phases observed in our experiments.« less

Assessment of calcium addition on the removal of U(VI) in the alkaline conditions created by NH 3 gas

DOE PAGES

Katsenovich, Yelena; Cardona, Claudia; Szecsody, Jim; ...

2018-03-06

Remediation of uranium (U) contamination in the deep vadose zone (VZ) sediments abundant in calcite mineral is a challenging task considering the formation of highly stable and mobile uranyl complexes with carbonate and calcium in pore water composition. There is a concern that uranium contamination in the VZ can serve as a continued source for groundwater pollution, creating a risk to human health and the environment through the groundwater pathway. This requires in-situ remediation of the radionuclide-contaminated VZ to convert soluble U species to low solubility precipitates that are stable in the natural environment. Injection of reactive gasses (e.g., NHmore » 3) is a promising technology to decrease U mobility in the unsaturated zone without the addition of liquid amendments. The NH 3 injection creates alkaline conditions that can alter the sediment pore water composition due to a release of elements from minerals (via desorption and dissolution) that are present in the sediment. However, it is not known how VZ pore water constituents (Si, Al 3+, HCO 3 -, and Ca 2 +) would affect U(VI) removal/precipitation in alkaline conditions. This study quantified the role of major pore water constituents typically present in the arid and semi-arid environments of the western regions of the U.S and identified solid uranium-bearing phases that could potentially precipitate from solutions approximating pore water compositions after pH manipulations via ammonia gas injections. Triplicate samples were prepared using six Si (5, 50 100, 150, 200, and 250 mM), six HCO 3 - (0, 3, 25, 50, 75, and 100 mM), and two Ca 2+ (5 and 10 mM) concentrations. The concentration of aluminum and uranium was kept constant at 5 mM and 0.0084 mM, respectively, in all synthetic formulations tested. Results showed that the percentage of U(VI) removal was controlled by the Si/Al molar ratios and Ca 2+ concentrations. Regardless of the bicarbonate concentration tested, the percentage of U(VI) removed increased as the Si/Al ratios were increased. However, higher Ca concentrations correlated with higher U(VI) removal, ranging between 96% and 99%, at low Si/Al ratios. The SEM images of dried precipitates displayed dense amorphous regions high in silica content, where EDS elemental analysis unveiled higher U atomic percentages. The formation of uranyl silicate and carbonate minerals was also predicted by the speciation modeling. XRD analysis revealed the presence of uranyl carbonate mineral phases (andersonite, grimselite); however, uranyl silicates predicted (Na-boltwoodite) were not identified experimentally, possibly due to the amorphous nature of the silica solid phases observed in our experiments.« less

The isothermal section of Gd–Ni–Si system at 1070 K

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morozkin, A.V., E-mail: morozkin@tech.chem.msu.ru; Knotko, A.V.; Yapaskurt, V.O.

2016-03-15

The Gd–Ni–Si system has been investigated at 1070 K by X-ray and microprobe analyses. The existence of the known compounds, i.e.: GdNi{sub 10}Si{sub 2}, GdNi{sub 8}Si{sub 3}, GdNi{sub 5}Si{sub 3}, GdNi{sub 7}Si{sub 6}, GdNi{sub 6}Si{sub 6}, GdNi{sub 4}Si, GdNi{sub 2}Si{sub 2}, GdNiSi{sub 3}, Gd{sub 3}Ni{sub 6}Si{sub 2}, GdNiSi, GdNiSi{sub 2}, GdNi{sub 0.4}Si{sub 1.6}, Gd{sub 2}Ni{sub 2.35}Si{sub 0.65}, Gd{sub 3}NiSi{sub 2}, Gd{sub 3}NiSi{sub 3} and Gd{sub 6}Ni{sub 1.67}Si{sub 3}, has been confirmed. Moreover, five new phases have been identified in this system. The crystal structure for four of them has been determined: Gd{sub 2}Ni{sub 16−12.8}Si{sub 1−4.2} (Th{sub 2}Zn{sub 17}-type), GdNi{sub 6.6}Si{submore » 6} (GdNi{sub 7}Si{sub 6}-type), Gd{sub 3}Ni{sub 8}Si (Y{sub 3}Co{sub 8}Si-type) and Gd{sub 3}Ni{sub 11.5}Si{sub 4.2}(Gd{sub 3}Ru{sub 4}Ga{sub 12}-type). The compound with composition ~Gd{sub 2}Ni{sub 4}Si{sub 3} still remains with unknown structure. Quasi-binary phases, solid solutions, were detected at 1070 K to be formed by the binaries GdNi{sub 5}, GdNi{sub 3}, GdNi{sub 2}, GdNi, GdSi{sub 2} and GdSi{sub 1.67}; while no appreciable solubility was observed for the other binary compounds of the Gd–Ni–Si system. Magnetic properties of the GdNi{sub 6}Si{sub 6}, GdNi{sub 6.6}Si{sub 6} and Gd{sub 3}Ni{sub 11.5}Si{sub 4.2} compounds have also been investigated and are here reported. - Graphical abstract: The Gd–Ni–Si system has been investigated at 1070 K by X-ray and microprobe analyses. The known GdNi{sub 10}Si{sub 2}, GdNi{sub 8}Si{sub 3}, GdNi{sub 5}Si{sub 3}, GdNi{sub 7}Si{sub 6}, GdNi{sub 6}Si{sub 6}, GdNi{sub 4}Si, GdNi{sub 2}Si{sub 2}, GdNiSi{sub 3}, Gd{sub 3}Ni{sub 6}Si{sub 2}, GdNiSi, GdNiSi{sub 2}, GdNi{sub 0.4}Si{sub 1.6}, Gd{sub 2}Ni{sub 2.35}Si{sub 0.65}, Gd{sub 3}NiSi{sub 2}, Gd{sub 3}NiSi{sub 3} and Gd{sub 6}Ni{sub 1.67}Si{sub 3} compounds have been confirmed and five new ~Gd{sub 2}Ni{sub 4}Si{sub 3} (unknown type), Gd{sub 2}Ni{sub 16−12.8}Si{sub 1−4.2} (Th{sub 2}Zn{sub 17}-type), GdNi{sub 6.6}Si{sub 6} (GdNi{sub 7}Si{sub 6}-type), Gd{sub 3}Ni{sub 8}Si (Y{sub 3}Co{sub 8}Si-type) and Gd{sub 3}Ni{sub 11.5}Si{sub 4.2} (Gd{sub 3}Ru{sub 4}Ga{sub 12}-type) compounds have been detected in Gd–Ni–Si system at 1070 K. Quasi-binary phases, solid solutions, were detected at 1070 K to be formed by the binaries GdNi{sub 5}, GdNi{sub 3}, GdNi{sub 2}, GdNi, GdSi{sub 2} and GdSi{sub 1.67}; while no detectable solubility was observed for the other binary compounds of the Gd–Ni–Si system. Magnetic properties of the GdNi{sub 6}Si{sub 6}, GdNi{sub 6.6}Si{sub 6} and Gd{sub 3}Ni{sub 11.5}Si{sub 4.2} compounds have also been investigated and are here reported. - Highlights: • Gd–Ni–Si isothermal section was obtained at 1070 K. • Sixteen known ternary gadolinium nickel silicides were confirmed in Gd–Ni–Si. • Five new gadolinium nickel silicides were detected in Gd–Ni–Si. • GdNi{sub 6}Si{sub 6}, GdNi{sub 6.6}Si{sub 6} and Gd{sub 3}Ni{sub 11.5}Si{sub 4.2} show ferromagnetic-type ordering.« less

Targeted Control of Permeability Using Carbonate Dissolution/Precipitation Reactions

NASA Astrophysics Data System (ADS)

Clarens, A. F.; Tao, Z.; Plattenberger, D.

2016-12-01

Targeted mineral precipitation reactions are a promising approach for controlling fluid flow in the deep subsurface. Here we studied the potential to use calcium and magnesium bearing silicates as cation donors that would react with aqueous phase CO2 under reservoir conditions to form solid carbonate precipitates. Preliminary experiments in high pressure and temperature columns suggest that these reactions can effectively lower the permeability of a porous media. Wollastonite (CaSiO3) was used as the model silicate, injected as solid particles into the pore space of a packed column, which was then subsequently flooded with CO2(aq). The reactions occur spontaneously, leveraging the favorable kinetics that occur at the high temperature and pressure conditions characteristic of the deep subsurface, to form solid phase calcium carbonate (CaCO3) and amorphous silica (SiO2) within the pore space. Both x-ray tomography imaging of reacted columns and electron microscopy imaging of thin sections were used to characterize where dissolution/precipitation occurred within the porous media. The spatial distribution of the products was closely tied to the flow rate and the duration of the experiment. The SiO2 product precipitated in close spatial proximity to the CaSiO3 reactant. The CaCO3 product, which is sensitive to the low pH and high pCO2 brine, precipitated out of solution further down the column as Ca2+ ions moved with the brine. The permeability of the columns decreased by several orders of magnitude after injecting the CaSiO3 particles. Following carbonation, the permeability decreased even further as precipitates filled flow paths within the pore network. A pore network model was developed to help understand the interplay between precipitation kinetics and flow in altering the permeability of the porous media. The effect of particle concentration and size, pore size, reaction time, and pCO2, are explored on pore/fracture aperture and reaction extent. To provide better control of these dynamics and ultimately devise a mechanism to deliver carbonation seed particles into leakage pathways, we are exploring the potential to functionalize the silicate particles using temperature sensitive polymer coatings.

GaN-on-Si blue/white LEDs: epitaxy, chip, and package

NASA Astrophysics Data System (ADS)

Qian, Sun; Wei, Yan; Meixin, Feng; Zengcheng, Li; Bo, Feng; Hanmin, Zhao; Hui, Yang

2016-04-01

The dream of epitaxially integrating III-nitride semiconductors on large diameter silicon is being fulfilled through the joint R&D efforts of academia and industry, which is driven by the great potential of GaN-on-silicon technology in improving the efficiency yet at a much reduced manufacturing cost for solid state lighting and power electronics. It is very challenging to grow high quality GaN on Si substrates because of the huge mismatch in the coefficient of thermal expansion (CTE) and the large mismatch in lattice constant between GaN and silicon, often causing a micro-crack network and a high density of threading dislocations (TDs) in the GaN film. Al-composition graded AlGaN/AlN buffer layers have been utilized to not only build up a compressive strain during the high temperature growth for compensating the tensile stress generated during the cool down, but also filter out the TDs to achieve crack-free high-quality n-GaN film on Si substrates, with an X-ray rocking curve linewidth below 300 arcsec for both (0002) and (101¯2) diffractions. Upon the GaN-on-Si templates, prior to the deposition of p-AlGaN and p-GaN layers, high quality InGaN/GaN multiple quantum wells (MQWs) are overgrown with well-engineered V-defects intentionally incorporated to shield the TDs as non-radiative recombination centers and to enhance the hole injection into the MQWs through the via-like structures. The as-grown GaN-on-Si LED wafers are processed into vertical structure thin film LED chips with a reflective p-electrode and the N-face surface roughened after the removal of the epitaxial Si(111) substrates, to enhance the light extraction efficiency. We have commercialized GaN-on-Si LEDs with an average efficacy of 150-160 lm/W for 1mm2 LED chips at an injection current of 350 mA, which have passed the 10000-h LM80 reliability test. The as-produced GaN-on-Si LEDs featured with a single-side uniform emission and a nearly Lambertian distribution can adopt the wafer-level phosphor coating procedure, and are suitable for directional lighting, camera flash, streetlighting, automotive headlamps, and otherlighting applications. Project supported financially by the National Natural Science Foundation of China (Nos. 61522407, 61534007, 61404156), the National High Technology Research and Development Program of China (No. 2015AA03A102), the Science & Technology Program of Jiangsu Province (Nos. BA2015099, BE2012063), the Suzhou Science & Technology Program (No. ZXG2013042), and the Recruitment Program of Global Experts (1000 Youth Talents Plan). Project also supported technically by Nano-X from SINANO, CAS

Hyaluronan degrading silica nanoparticles for skin cancer therapy

NASA Astrophysics Data System (ADS)

Scodeller, P.; Catalano, P. N.; Salguero, N.; Duran, H.; Wolosiuk, A.; Soler-Illia, G. J. A. A.

2013-09-01

We report the first nanoformulation of Hyaluronidase (Hyal) and its enhanced adjuvant effect over the free enzyme. Hyaluronic acid (HA) degrading enzyme Hyal was immobilized on 250 nm silica nanoparticles (SiNP) maintaining specific activity of the enzyme via the layer-by-layer self-assembly technique. This process was characterized by dynamic light scattering (DLS), zeta potential, infrared and UV-Vis spectroscopy, transmission electron microscopy (TEM) and enzymatic activity measurements. The nanoparticles were tested in vivo as adjuvants of carboplatin (CP), peritumorally injected in A375 human melanoma bearing mice and compared with the non-immobilized enzyme, on the basis of equal enzymatic activity. Alcian Blue staining of A375 tumors indicated large overexpression of hyaluronan. At the end of the experiment, tumor volume reduction with SiNP-immobilized Hyal was significantly enhanced compared to non-immobilized Hyal. Field emission scanning electron microscopy (FE-SEM) images together with energy dispersive X-ray spectroscopy (EDS) spectra confirmed the presence of SiNP on the tumor. We mean a proof of concept: this extracellular matrix (ECM) degrading enzyme, immobilized on SiNP, is a more effective local adjuvant of cancer drugs than the non-immobilized enzyme. This could prove useful in future therapies using other or a combination of ECM degrading enzymes.We report the first nanoformulation of Hyaluronidase (Hyal) and its enhanced adjuvant effect over the free enzyme. Hyaluronic acid (HA) degrading enzyme Hyal was immobilized on 250 nm silica nanoparticles (SiNP) maintaining specific activity of the enzyme via the layer-by-layer self-assembly technique. This process was characterized by dynamic light scattering (DLS), zeta potential, infrared and UV-Vis spectroscopy, transmission electron microscopy (TEM) and enzymatic activity measurements. The nanoparticles were tested in vivo as adjuvants of carboplatin (CP), peritumorally injected in A375 human melanoma bearing mice and compared with the non-immobilized enzyme, on the basis of equal enzymatic activity. Alcian Blue staining of A375 tumors indicated large overexpression of hyaluronan. At the end of the experiment, tumor volume reduction with SiNP-immobilized Hyal was significantly enhanced compared to non-immobilized Hyal. Field emission scanning electron microscopy (FE-SEM) images together with energy dispersive X-ray spectroscopy (EDS) spectra confirmed the presence of SiNP on the tumor. We mean a proof of concept: this extracellular matrix (ECM) degrading enzyme, immobilized on SiNP, is a more effective local adjuvant of cancer drugs than the non-immobilized enzyme. This could prove useful in future therapies using other or a combination of ECM degrading enzymes. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr02787b

Evaluation of ceramics for stator application: Gas turbine engine report

NASA Technical Reports Server (NTRS)

Trela, W.; Havstad, P. H.

1978-01-01

Current ceramic materials, component fabrication processes, and reliability prediction capability for ceramic stators in an automotive gas turbine engine environment are assessed. Simulated engine duty cycle testing of stators conducted at temperatures up to 1093 C is discussed. Materials evaluated are SiC and Si3N4 fabricated from two near-net-shape processes: slip casting and injection molding. Stators for durability cycle evaluation and test specimens for material property characterization, and reliability prediction model prepared to predict stator performance in the simulated engine environment are considered. The status and description of the work performed for the reliability prediction modeling, stator fabrication, material property characterization, and ceramic stator evaluation efforts are reported.

Electro-magnetic transport and rectifying property of Fe{sub 2.5}Mn{sub 0.5}O{sub 4}/p-Si heterojunction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aireddy, H.; Das, A. K., E-mail: amal@phy.iitkgp.ernet.in

2016-05-06

Fe{sub 2.5}Mn{sub 0.5}O{sub 4}/p-Si heterojunction was fabricated using a pulsed laser deposition technique and investigated it’s structural and electrical transport properties. The high-resolution transmission electron microscopy results reveal the formation of a polycrystalline film on silicon substrate. The heterojunction shows good rectifying property and giant negative junction magnetoresistance especially in reverse bias condition at room temperature. The origin of this giant negative junction magnetoresistance may be attributing to the injection of electrons to the majority spin-up band of the Fe{sub 2.5}Mn{sub 0.5}O{sub 4} film.

RNase non-sensitive and endocytosis independent siRNA delivery system: delivery of siRNA into tumor cells and high efficiency induction of apoptosis

NASA Astrophysics Data System (ADS)

Jiang, Xinglu; Wang, Guobao; Liu, Ru; Wang, Yaling; Wang, Yongkui; Qiu, Xiaozhong; Gao, Xueyun

2013-07-01

To date, RNase degradation and endosome/lysosome trapping are still serious problems for siRNA-based molecular therapy, although different kinds of delivery formulations have been tried. In this report, a cell penetrating peptide (CPP, including a positively charged segment, a linear segment, and a hydrophobic segment) and a single wall carbon nanotube (SWCNT) are applied together by a simple method to act as a siRNA delivery system. The siRNAs first form a complex with the positively charged segment of CPP via electrostatic forces, and the siRNA-CPP further coats the surface of the SWCNT via hydrophobic interactions. This siRNA delivery system is non-sensitive to RNase and can avoid endosome/lysosome trapping in vitro. When this siRNA delivery system is studied in Hela cells, siRNA uptake was observed in 98% Hela cells, and over 70% mRNA of mammalian target of rapamycin (mTOR) is knocked down, triggering cell apoptosis on a significant scale. Our siRNA delivery system is easy to handle and benign to cultured cells, providing a very efficient approach for the delivery of siRNA into the cell cytosol and cleaving the target mRNA therein.

Recent progress in Si thin film technology for solar cells

NASA Astrophysics Data System (ADS)

Kuwano, Yukinori; Nakano, Shoichi; Tsuda, Shinya

1991-11-01

Progress in Si thin film technology 'specifically amorphous Si (a-Si) and polycrystalline Si (poly-Si) thin film' for solar cells is summarized here from fabrication method, material, and structural viewpoints. In addition to a-Si, primary results on poly-Si thin film research are discussed. Various applications for a-Si solar cells are mentioned, and consumer applications and a-Si solar cell photovoltaic systems are introduced. New product developments include see-through solar cells, solar cell roofing tiles, and ultra-light flexible solar cells. As for new systems, air conditioning equipment powered by solar cells is described. Looking to the future, the proposed GENESIS project is discussed.

Landscape cultivation alters δ30Si signature in terrestrial ecosystems.

NASA Astrophysics Data System (ADS)

Vandevenne, F. I.; Delvaux, C.; Huyghes, H.; Ronchi, B.; Govers, G.; Barão, A. L.; Clymans, W.; Meire, P.; André, L.; Struyf, E.

2014-12-01

Despite increasing recognition of the importance of biological Si cycling in controlling dissolved Si (DSi) in soil and stream water, effects of human cultivation on the Si cycle remain poorly understood. Sensitive tracer techniques to identify and quantify Si in the soil-plant-water system could be highly relevant in addressing these uncertainties. Stable Si isotopes are promising tools to define Si sources and sinks along the ecosystem flow path, as intense fractionation occurs during chemical weathering and uptake of dissolved Si in plants. Yet they remain underexploited in the end product of the soil-plant system: the soil water. Here, stable Si isotope ratios (δ30Si) of dissolved Si in soil water were measured along a land use gradient (continuous forest, continuous pasture, young cropland and continuous cropland) with similar parent material (loess) and homogenous bulk mineralogical and climatological properties (Belgium). Soil water δ30Si signatures are clearly separated along the gradient, with highest average signatures in continuous cropland (+1.61‰), intermediate in pasture (+1.05‰) and young cropland (+0.89 ‰) and lowest in forest soil water (+0.62‰). Our data do not allow distinguishing biological from pedogenic/lithogenic processes, but point to a strong interaction of both. We expect that increasing export of light isotopes in disturbed land uses (i.e. through agricultural harvest), and higher recycling of 28Si and elevated weathering intensity (including clay dissolution) in forest systems will largely determine soil water δ30Si signatures of our systems. Our results imply that soil water δ30Si signature is biased through land management before it reaches rivers and coastal zones, where other fractionation processes take over (e.g. diatom uptake and reverse weathering in floodplains). In particular, a direct role of agriculture systems in lowering export Si fluxes towards rivers and coastal systems has been shown. Stable Si isotopes have a large potential to track human disturbance on the Si cycle, including subtle changes in clay evolution and biogenic sink/source functions as induced by land use conversions.

Landscape cultivation alters δ30Si signature in terrestrial ecosystems

NASA Astrophysics Data System (ADS)

Vandevenne, Floor; Delvaux, Claire; Hughes, Harold; Ronchi, Benedicta; Clymans, Wim; Barao, Ana Lucia; Govers, Gerard; Cornelis, Jean Thomas; André, Luc; Struyf, Eric

2015-04-01

Despite increasing recognition of the importance of biological Si cycling in controlling dissolved Si (DSi) in soil and stream water, effects of human cultivation on the Si cycle remain poorly understood. Sensitive tracer techniques to identify and quantify Si in the soil-plant-water system could be highly relevant in addressing these uncertainties. Stable Si isotopes are promising tools to define Si sources and sinks along the ecosystem flow path, as intense fractionation occurs during chemical weathering and uptake of dissolved Si in plants. Yet they remain underexploited in the end product of the soil-plant system: the soil water. Here, stable Si isotope ratios (δ30Si) of dissolved Si in soil water were measured along a land use gradient (continuous forest, continuous pasture, young cropland and continuous cropland) with similar parent material (loess) and homogenous bulk mineralogical and climatological (Belgium). Soil water δ30Si signatures are clearly separated along the gradient, with highest average signatures in continuous cropland (+1.61%), intermediate in pasture (+1.05%) and young cropland (+0.89%) and lowest in forest soil water (+0.62%). Our data do not allow distinguishing biological from pedogenic/lithogenic processes, but point to a strong interaction of both. We expect that increasing export of light isotopes in disturbed land uses (i.e. through agricultural harvest), and higher recycling of 28Si and elevated weathering intensity (including clay dissolution) in forest systems will largely determine soil water δ30Si signatures of our systems. Our results imply that soil water δ30Si signature is biased through land management before it reaches rivers and coastal zones, where other fractionation processes take over (e.g. diatom uptake and reverse weathering in floodplains). In particular, a direct role of agriculture systems in lowering export Si fluxes towards rivers and coastal systems has been shown. Stable Si isotopes have a large potential to track human disturbance on the Si cycle, including subtle changes in clay evolution and biogenic sink/source functions as induced by land use conversions.

Recrystallization in Si upon ion irradiation at room temperature in Co/Si(111) thin film systems

NASA Astrophysics Data System (ADS)

Banu, Nasrin; Satpati, B.; Dev, B. N.

2018-04-01

After several decades of research it was concluded that for a constant flux recrystallization in Si upon ion irradiation is possible only at high temperature. At low temperature or at room temperature only amorphization can take place. However we have observed recrystallization in Si upon ion irradiation at room temperature in a Co/Si thin film system. The Co/Si sample was prepared by deposition of 25 nm Co on clean Si(111) substrate. An oxide layer (˜ 2nm) of cobalt at the top of the film due to air exposure. The ion irradiation was done at room temperature under high vacuum with 1MeV Si+ ion with low beam current < 400 nA. Earlier we have shown similar ion induced recrystallization in Si(100) substrate which had a sandwich Si/Ni/Si structure. This system had an epitaxial buffer Si layer on Si substrate. This study also shows that the phenomenon is independent of substrate orientation and buffer layer. We have used transmission electron microscopy (TEM) to study the recrystallization behavior.

Diffusion Bonding Technology of Tungsten and SiC/SiC Composites for Nuclear Applications

NASA Astrophysics Data System (ADS)

Kishimoto, Hirotatsu; Shibayama, Tamaki; Abe, Takahiro; Shimoda, Kazuya; Kawamura, Satoshi; Kohyama, Akira

2011-10-01

Silicon carbide (SiC) is a candidate for the structural material in the next generation nuclear plants. Use of SiC/SiC composites is expected to increase the operation temperature of system over 1000 °C. For the high temperature system, refractory metals are planned to be used for several components. Tungsten is a candidate of armor on the divertor component in fusion, and is planned to be used for an upper-end plug of SiC/SiC fuel pin in a Gas cooled Fast Reactor (GFR). Joining technique of the SiC/SiC composites and tungsten is an important issue for nuclear systems in future. Nano-Infiltration and Transient Eutectoid (NITE) method is able to provide dense stable and high strength SiC/SiC composites having high resistance against pressure at elevated temperature, a diffusion bonding technique is usable to join the materials. Present research produces a NITE-SiC/SiC composite and tungsten as the similar dimension as a projected cladding tube of fuel pin for GFR using diffusion bonding, and investigated microstructure and mechanical properties.

A detailed study on the working mechanism of a heteropoly acid modified TiO2 photoanode for efficient dye-sensitized solar cells.

PubMed

Jiang, Yanxia; Yang, Yulin; Qiang, Liangsheng; Fan, Ruiqing; Li, Liang; Ye, Tengling; Na, Yong; Shi, Yan; Luan, Tianzhu

2015-03-14

A novel heteropolyacid (HPA) K6SiW11O39Ni(H2O)·xH2O (SiW11Ni) modified TiO2 has been successfully synthesized and introduced into the photoanode of dye-sensitized solar cells (DSSCs). The performance of the cell with the HPA-modified photoanode (SiW11Ni/TiO2), mixed with P25 powder in the ratio of 2 : 8, is better than the cell with a pristine P25 photoanode. An increase of 31% in the photocurrent and 22% improvement in the conversion efficiency are obtained. The effect of the heteropolyacid was well studied by UV-vis spectroscopy, spectro-electrochemical spectroscopy, dark current, intensity-modulated photocurrent spectroscopy and intensity-modulated photovoltage spectroscopy, open-circuit voltage decay and electrochemical impedance spectroscopy. The results show that the interfacial layer modified by SiW11Ni can enhance the injection and transport of electrons, and then retard the recombination of electrons, which results in a longer electron lifetime. What's more, the introduction of SiW11Ni can simultaneously broaden the absorption in the visible region, eventually leading to an efficient increase in energy conversion efficiency.

In Vivo Tumor Targeting and Image-Guided Drug Delivery with Antibody-Conjugated, Radiolabeled Mesoporous Silica Nanoparticles

PubMed Central

Chen, Feng; Hong, Hao; Zhang, Yin; Valdovinos, Hector F.; Shi, Sixiang; Kwon, Glen S.; Theuer, Charles P.; Barnhart, Todd E.; Cai, Weibo

2013-01-01

Since the first use of biocompatible mesoporous silica (mSiO2) nanoparticles as drug delivery vehicles, in vivo tumor targeted imaging and enhanced anti-cancer drug delivery has remained a major challenge. In this work, we describe the development of functionalized mSiO2 nanoparticles for actively targeted positron emission tomography (PET) imaging and drug delivery in 4T1 murine breast tumor-bearing mice. Our structural design involves the synthesis, surface functionalization with thiol groups, PEGylation, TRC105 antibody (specific for CD105/endoglin) conjugation, and 64Cu-labeling of uniform 80 nm sized mSiO2 nanoparticles. Systematic in vivo tumor targeting studies clearly demonstrated that 64Cu-NOTA-mSiO2-PEG-TRC105 could accumulate prominently at the 4T1 tumor site via both the enhanced permeability and retention effect and TRC105-mediated binding to tumor vasculature CD105. As a proof-of-concept, we also demonstrated successful enhanced tumor targeted delivery of doxorubicin (DOX) in 4T1 tumor-bearing mice after intravenous injection of DOX-loaded NOTA-mSiO2-PEG-TRC105, which holds great potential for future image-guided drug delivery and targeted cancer therapy. PMID:24083623

Formation of SiGe nanocrystals embedded in Al2O3 for the application of write-once-read-many-times memory

NASA Astrophysics Data System (ADS)

Wu, Min-Lin; Wu, Yung-Hsien; Lin, Chia-Chun; Chen, Lun-Lun

2012-10-01

The structure of SiGe nanocrystals embedded in Al2O3 formed by sequential deposition of Al2O3/Si/Ge/Al2O3 and a subsequent annealing was confirmed by transmission electron microscopy and energy dispersive spectroscopy (EDS), and its application for write-once-read-many-times (WORM) memory devices was explored in this study. By applying a -10 V pulse for 1 s, a large amount of holes injected from Si substrate are stored in the nanocrystals and consequently, the current at +1.5 V increases by a factor of 104 as compared to that of the initial state. Even with a smaller -5 V pulse for 1 μs, a sufficiently large current ratio of 36 can still be obtained, verifying the low power operation. Since holes are stored in nanocrystals which are isolated from Si substrate by Al2O3 with good integrity and correspond to a large valence band offset with respect to Al2O3, desirable read endurance up to 105 cycles and excellent retention over 100 yr are achieved. Combining these promising characteristics, WORM memory devices are appropriate for high-performance archival storage applications.

Asymmetric dimethylarginine contributes to retinal neovascularization of diabetic retinopathy through EphrinB2 pathway.

PubMed

Du, Mei-Rong; Yan, Li; Li, Nian-Sheng; Wang, Yu-Jie; Zhou, Ting; Jiang, Jun-Lin

2018-05-16

Diabetic retinopathy (DR) is a leading cause of vision loss with retinal neovascularization. This study aims to investigate whether Asymmetric dimethylarginine (ADMA) impacts the pathogenesis of DR via focusing on promoting retinal neovascularization and its underlying molecular mechanisms. Diabetic rats were induced by a single intraperitoneal injection of streptozotocin (STZ) for 20 weeks. ADMA levels in aqueous and the influence of hypoxia on ADMA and angiogenesis in RF/6A cells were examined. The effects and underlying molecular mechanisms of ADMA on neovascularization of RF/6A cells were further evaluated by administration of ADMA, DDAH siRNA or ephrinB2 siRNA. Results showed that ADMA levels were elevated in both aqueous from diabetic rats and culture medium in RF/6A cells pretreated with hypoxia. Administration of ADMA directly promoted proliferation, migration, adhesion and tube formation of RF/6A cells, which was further confirmed by DDAH1 siRNA or DDAH2 siRNA. In addition, ephrinB2 expression was increased under diabetic conditions, and the angiogenic effects of ADMA were blocked by ephrinB2 siRNA. In conclusion, ADMA contributes to the neovascularization of retina in diabetic mellitus, which is regulated by ephrinB2. Copyright © 2018 Elsevier Inc. All rights reserved.

Electrical characterization of amorphous Al2O3 dielectric films on n-type 4H-SiC

NASA Astrophysics Data System (ADS)

Khosa, R. Y.; Thorsteinsson, E. B.; Winters, M.; Rorsman, N.; Karhu, R.; Hassan, J.; Sveinbjörnsson, E. Ö.

2018-02-01

We report on the electrical properties of Al2O3 films grown on 4H-SiC by successive thermal oxidation of thin Al layers at low temperatures (200°C - 300°C). MOS capacitors made using these films contain lower density of interface traps, are more immune to electron injection and exhibit higher breakdown field (5MV/cm) than Al2O3 films grown by atomic layer deposition (ALD) or rapid thermal processing (RTP). Furthermore, the interface state density is significantly lower than in MOS capacitors with nitrided thermal silicon dioxide, grown in N2O, serving as the gate dielectric. Deposition of an additional SiO2 film on the top of the Al2O3 layer increases the breakdown voltage of the MOS capacitors while maintaining low density of interface traps. We examine the origin of negative charges frequently encountered in Al2O3 films grown on SiC and find that these charges consist of trapped electrons which can be released from the Al2O3 layer by depletion bias stress and ultraviolet light exposure. This electron trapping needs to be reduced if Al2O3 is to be used as a gate dielectric in SiC MOS technology.

Light-activated resistance switching in SiOx RRAM devices

NASA Astrophysics Data System (ADS)

Mehonic, A.; Gerard, T.; Kenyon, A. J.

2017-12-01

We report a study of light-activated resistance switching in silicon oxide (SiOx) resistive random access memory (RRAM) devices. Our devices had an indium tin oxide/SiOx/p-Si Metal/Oxide/Semiconductor structure, with resistance switching taking place in a 35 nm thick SiOx layer. The optical activity of the devices was investigated by characterising them in a range of voltage and light conditions. Devices respond to illumination at wavelengths in the range of 410-650 nm but are unresponsive at 1152 nm, suggesting that photons are absorbed by the bottom p-type silicon electrode and that generation of free carriers underpins optical activity. Applied light causes charging of devices in the high resistance state (HRS), photocurrent in the low resistance state (LRS), and lowering of the set voltage (required to go from the HRS to LRS) and can be used in conjunction with a voltage bias to trigger switching from the HRS to the LRS. We demonstrate negative correlation between set voltage and applied laser power using a 632.8 nm laser source. We propose that, under illumination, increased electron injection and hence a higher rate of creation of Frenkel pairs in the oxide—precursors for the formation of conductive oxygen vacancy filaments—reduce switching voltages. Our results open up the possibility of light-triggered RRAM devices.

RNAi-mediated silencing of hepatic Alas1 effectively prevents and treats the induced acute attacks in acute intermittent porphyria mice.

PubMed

Yasuda, Makiko; Gan, Lin; Chen, Brenden; Kadirvel, Senkottuvelan; Yu, Chunli; Phillips, John D; New, Maria I; Liebow, Abigail; Fitzgerald, Kevin; Querbes, William; Desnick, Robert J

2014-05-27

The acute hepatic porphyrias are inherited disorders of heme biosynthesis characterized by life-threatening acute neurovisceral attacks. Factors that induce the expression of hepatic 5-aminolevulinic acid synthase 1 (ALAS1) result in the accumulation of the neurotoxic porphyrin precursors 5-aminolevulinic acid (ALA) and porphobilinogen (PBG), which recent studies indicate are primarily responsible for the acute attacks. Current treatment of these attacks involves i.v. administration of hemin, but a faster-acting, more effective, and safer therapy is needed. Here, we describe preclinical studies of liver-directed small interfering RNAs (siRNAs) targeting Alas1 (Alas1-siRNAs) in a mouse model of acute intermittent porphyria, the most common acute hepatic porphyria. A single i.v. dose of Alas1-siRNA prevented the phenobarbital-induced biochemical acute attacks for approximately 2 wk. Injection of Alas1-siRNA during an induced acute attack significantly decreased plasma ALA and PBG levels within 8 h, more rapidly and effectively than a single hemin infusion. Alas1-siRNA was well tolerated and a therapeutic dose did not cause hepatic heme deficiency. These studies provide proof-of-concept for the clinical development of RNA interference therapy for the prevention and treatment of the acute attacks of the acute hepatic porphyrias.

Development of a process for high capacity arc heater production of silicon for solar arrays

NASA Technical Reports Server (NTRS)

Meyer, T. N.

1980-01-01

A high temperature silicon production process using existing electric arc heater technology is discussed. Silicon tetrachloride and a reductant, liquid sodium, were injected into an arc heated mixture of hydrogen and argon. Under these high temperature conditions, a very rapid reaction occurred, yielding silicon and gaseous sodium chloride. Techniques for high temperature separation and collection of the molten silicon were developed. The desired degree of separation was not achieved. The electrical, control and instrumentation, cooling water, gas, SiCl4, and sodium systems are discussed. The plasma reactor, silicon collection, effluent disposal, the gas burnoff stack, and decontamination and safety are also discussed. Procedure manuals, shakedown testing, data acquisition and analysis, product characterization, disassembly and decontamination, and component evaluation are reviewed.

Creep Behavior of Hafnia and Ytterbium Silicate Environmental Barrier Coating Systems on SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Fox, Dennis S.; Ghosn, Louis J.; Harder, Bryan

2011-01-01

Environmental barrier coatings will play a crucial role in future advanced gas turbine engines because of their ability to significantly extend the temperature capability and stability of SiC/SiC ceramic matrix composite (CMC) engine components, thus improving the engine performance. In order to develop high performance, robust coating systems for engine components, appropriate test approaches simulating operating temperature gradient and stress environments for evaluating the critical coating properties must be established. In this paper, thermal gradient mechanical testing approaches for evaluating creep and fatigue behavior of environmental barrier coated SiC/SiC CMC systems will be described. The creep and fatigue behavior of Hafnia and ytterbium silicate environmental barrier coatings on SiC/SiC CMC systems will be reported in simulated environmental exposure conditions. The coating failure mechanisms will also be discussed under the heat flux and stress conditions.

An Ablation Technique for Enhancing Reentry Antenna Performance; Flight Test Results

DTIC Science & Technology

1974-11-14

from a single station on the vehicle. To measure the spread cf the additive alnd its effects as it proceeded back along the vehicle and r,:act• td ...injection: pair of electrosta 2.40, biased ± 3uV )N ඊ Si0-.--.I0A Examination of Figure 39 shows a much different picture for Freon. Super- k. posed

Graphene-on-GaN Hot Electron Transistor

NASA Astrophysics Data System (ADS)

Zubair, Ahmad; Nourbakhsh, Amirhasan; Hong, Jin-Yong; Song, Yi; Qi, Meng; Jena, Debdeep; Kong, Jing; Dresselhaus, Mildred S.; Palacios, Tomas

Hot electron transistors (HETs) are promising devices for potential high-frequency operation that currently CMOS cannot provide. In an HET, carrier transport is due to the injection of hot electrons from an emitter to a collector which is modulated by a base electrode. Therefore, ultra-thin base electrodes are needed to facilitate ultra-short transit time and high performance for THz operation range. In this regard, graphene, the thinnest conductive membrane in nature, is considered the best candidate for the base material in HETs. The existing HETs with SiO2/Si as emitter stack suffer from low current gain and output current density. In this work, we use the two-dimensional electron gas (2-DEG) in a GaN-based heterostructure as emitter and monolayer graphene as the base electrode. The transport study of the proof-of-concept device shows high output current density (>50 A/cm2) , current gain (>3) and ballistic injection efficiency of 75%. These results indicate that performance parameters can be further improved by engineering the band offset of the graphene/collector stack and improved interface between graphene and GaN. Army Research Office (ARO) (Grant Nos. W911NF-14-2-0071, 6930265, and 6930861).

Advanced Environmental Barrier Coating Development for SiC/SiC Ceramic Matrix Composites: NASA's Perspectives

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2016-01-01

This presentation reviews NASA environmental barrier coating (EBC) system development programs and the coating materials evolutions for protecting the SiC/SiC Ceramic Matrix Composites in order to meet the next generation engine performance requirements. The presentation focuses on several generations of NASA EBC systems, EBC-CMC component system technologies for SiC/SiC ceramic matrix composite combustors and turbine airfoils, highlighting the temperature capability and durability improvements in simulated engine high heat flux, high pressure, high velocity, and with mechanical creep and fatigue loading conditions. The current EBC development emphasis is placed on advanced NASA 2700F candidate environmental barrier coating systems for SiC/SiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. Major technical barriers in developing environmental barrier coating systems, the coating integrations with next generation CMCs having the improved environmental stability, erosion-impact resistance, and long-term fatigue-environment system durability performance are described. The research and development opportunities for advanced turbine airfoil environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling are discussed.

Pentaatomic planar tetracoordinate silicon with 14 valence electrons: a large-scale global search of SiX(n)Y(m)(q) (n + m = 4; q = 0, ±1, -2; X, Y = main group elements from H to Br).

PubMed

Xu, Jing; Ding, Yi-hong

2015-03-05

Designing and characterizing the compounds with exotic structures and bonding that seemingly contrast the traditional chemical rules are a never-ending goal. Although the silicon chemistry is dominated by the tetrahedral picture, many examples with the planar tetracoordinate-Si skeletons have been discovered, among which simple species usually contain the 17/18 valence electrons. In this work, we report hitherto the most extensive structural search for the pentaatomic ptSi with 14 valence electrons, that is, SiXnYm(q) (n + m = 4; q = 0, ±1, -2; X, Y = main group elements from H to Br). For 129 studied systems, 50 systems have the ptSi structure as the local minimum. Promisingly, nine systems, that is, Li3SiAs(2-), HSiY3 (Y = Al/Ga), Ca3SiAl(-), Mg4Si(2-), C2LiSi, Si3Y2 (Y = Li/Na/K), each have the global minimum ptSi. The former six systems represent the first prediction. Interestingly, in HSiY3 (Y = Al/Ga), the H-atom is only bonded to the ptSi-center via a localized 2c-2e σ bond. This sharply contradicts the known pentaatomic planar-centered systems, in which the ligands are actively involved in the ligand-ligand bonding besides being bonded to the planar center. Therefore, we proposed here that to generalize the 14e-ptSi, two strategies can be applied as (1) introducing the alkaline/alkaline-earth elements and (2) breaking the peripheral bonding. In light of the very limited global ptSi examples, the presently designed six systems with 14e are expected to enrich the exotic ptSi chemistry and welcome future laboratory confirmation. © 2014 Wiley Periodicals, Inc.

Location and Electronic Nature of Phosphorus in the Si Nanocrystal − SiO2 System

PubMed Central

König, Dirk; Gutsch, Sebastian; Gnaser, Hubert; Wahl, Michael; Kopnarski, Michael; Göttlicher, Jörg; Steininger, Ralph; Zacharias, Margit; Hiller, Daniel

2015-01-01

Up to now, no consensus exists about the electronic nature of phosphorus (P) as donor for SiO2-embedded silicon nanocrystals (SiNCs). Here, we report on hybrid density functional theory (h-DFT) calculations of P in the SiNC/SiO2 system matching our experimental findings. Relevant P configurations within SiNCs, at SiNC surfaces, within the sub-oxide interface shell and in the SiO2 matrix were evaluated. Atom probe tomography (APT) and its statistical evaluation provide detailed spatial P distributions. For the first time, we obtain ionisation states of P atoms in the SiNC/SiO2 system at room temperature using X-ray absorption near edge structure (XANES) spectroscopy, eliminating structural artefacts due to sputtering as occurring in XPS. K energies of P in SiO2 and SiNC/SiO2 superlattices (SLs) were calibrated with non-degenerate P-doped Si wafers. results confirm measured core level energies, connecting and explaining XANES spectra with h-DFT electronic structures. While P can diffuse into SiNCs and predominantly resides on interstitial sites, its ionization probability is extremely low, rendering P unsuitable for introducing electrons into SiNCs embedded in SiO2. Increased sample conductivity and photoluminescence (PL) quenching previously assigned to ionized P donors originate from deep defect levels due to P. PMID:25997696

Computer Controlled Microwave Oven System for Rapid Water Content Determination

DTIC Science & Technology

1988-11-01

Codes - .d/or CONTENTS Page PREFACE .................................................................... 1 CONVERSION FACTORS, NON- SI TO SI (METRIC...CONVERSION FACTORS, NON- SI TO SI (METRIC) UNITS OF MEASUREMENT Non- SI units of measurement used in this report can be converted to SI (metric) units as...formula: C = (5/9)(F - 32) . To obtain Kelvin ( K ) readings, use: K = (5/9)(F - 32) + 273.15 3 COMPUTER CONTROLLED MICROWAVE OVEN SYSTEM FOR RAPID WATER

MARMOT Phase-Field Model for the U-Si System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aagesen, Larry Kenneth; Schwen, Daniel

2016-09-01

A phase-field model for the U-Si system has been implemented in MARMOT. The free energies for the phases relevant to accident-tolerant fuel applications (U 3Si 2, USi, U 3Si, and liquid) were implemented as free energy materials within MARMOT. A new three-phase phase-field model based on the concepts of the Kim-Kim-Suzuki two-phase model was developed and implemented in the MOOSE phase-field module. Key features of this model are that two-phase interfaces are stable with respect to formation of the third phase, and that arbitrary phase free energies can be used. The model was validated using a simplified three-phase system andmore » the U-Si system. In the U-Si system, the model correctly reproduced three-phase coexistence in a U 3Si 2-liquid-USi system at the eutectic temperature, solidification of a three-phase mixture below the eutectic temperature, and complete melting of a three-phase mixture above the eutectic temperature.« less

Experimental Insights into Multiphase (H2O-CO2) Fluid-Rock Interactions in Geothermal Systems

NASA Astrophysics Data System (ADS)

Kaszuba, J. P.; Lo Re, C.; Martin, J.; McPherson, B. J.; Moore, J. N.

2012-12-01

Integrated hydrothermal experiments and geochemical modeling elucidate fluid-rock interactions and reaction pathways in both natural and anthropogenic systems, including enhanced geothermal systems (EGS) in which CO2 is introduced as a working fluid. Experiments are conducted in rocker bombs and flexible Au-Ti reaction cells. Individual experiments require one to three months to complete; intensive in-situ fluid/gas sampling gauges reaction progress. Investigation of granitic reservoirs and associated vein minerals are broadly based on the Roosevelt Hot Springs thermal area, Utah, USA. The granite consists of subequal amounts of quartz, perthitic K-feldspar (~25% wt% albite and 75% wt% K-feldspar), and oligoclase (An23), and 4 wt% Fe-rich biotite. Vein minerals include epidote and chlorite (clinochlore). Experiments are conducted at 250°C and 25 to 45 MPa. Each experiment uses mineral powders (75 wt% of rock mass, ground to <45 um) to increase reactivity and also mineral pieces (0.1-0.7 cm in size) to promote petrologic evaluation of mineral reactions. The water (I ≈ 0.1 molal) initially contains millimolal quantities of SiO2, Al, Ca, Mg, K, SO4, and HCO3 and is designed to be saturated with all of the minerals present at the start of each experiment. Excess CO2 is injected to saturate the water and maintain an immiscible supercritical fluid phase. The entire evolutionary path of the natural system is not replicated at laboratory scales. Instead, experiments define a segment of the reaction path and, in combination with geochemical modeling, provide clear trajectories towards equilibrium. Reaction of granite+water yields illite+zeolite; smectite subsequently precipitates in response to CO2 injection. Reaction of granite+epidote+water yields illite+zeolite+smectite; zeolite does not precipitate after CO2 is injected. Water in all experiments become saturated with chalcedony. Carbonate minerals do not precipitate but are predicted as final equilbrium products. Enhanced Geothermal Systems are expected to follow similar reaction pathways and produce metastable minerals during initial development.

Down-Regulation of Hippocampal Genes Regulating Dopaminergic, GABAergic, and Glutamatergic Function Following Combined Neonatal Phencyclidine and Post-Weaning Social Isolation of Rats as a Neurodevelopmental Model for Schizophrenia

PubMed Central

Gaskin, Philip LR; Toledo-Rodriguez, Maria; Alexander, Stephen PH

2016-01-01

Background: Dysfunction of dopaminergic, GABAergic, and glutamatergic function underlies many core symptoms of schizophrenia. Combined neonatal injection of the N-methyl-D-aspartate (NMDA) receptor antagonist, phencyclidine (PCP), and post-weaning social isolation of rats produces a behavioral syndrome with translational relevance to several core symptoms of schizophrenia. This study uses DNA microarray to characterize alterations in hippocampal neurotransmitter-related gene expression and examines the ability of the sodium channel blocker, lamotrigine, to reverse behavioral changes in this model. Methods: Fifty-four male Lister-hooded rat pups either received phencyclidine (PCP, 10mg/kg, s.c.) on post-natal days (PND) 7, 9, and 11 before being weaned on PND 23 into separate cages (isolation; PCP-SI; n = 31) or received vehicle injection and group-housing (2–4 per cage; V-GH; n = 23) from weaning. The effect of lamotrigine on locomotor activity, novel object recognition, and prepulse inhibition of acoustic startle was examined (PND 60–75) and drug-free hippocampal gene expression on PND 70. Results: Acute lamotrigine (10–15mg/kg i.p.) reversed the hyperactivity and novel object recognition impairment induced by PCP-SI but had no effect on the prepulse inhibition deficit. Microarray revealed small but significant down-regulation of hippocampal genes involved in glutamate metabolism, dopamine neurotransmission, and GABA receptor signaling and in specific schizophrenia-linked genes, including parvalbumin (PVALB) and GAD67, in PCP-SI rats, which resemble changes reported in schizophrenia. Conclusions: Findings indicate that alterations in dopamine neurotransmission, glutamate metabolism, and GABA signaling may contribute to some of the behavioral deficits observed following PCP-SI, and that lamotrigine may have some utility as an adjunctive therapy to improve certain cognitive deficits symptoms in schizophrenia. PMID:27382048

Amplified spontaneous emission from ZnO in n-ZnO/ZnO nanodots-SiO(2) composite/p-AlGaN heterojunction light-emitting diodes.

PubMed

Shih, Ying Tsang; Wu, Mong Kai; Li, Wei Chih; Kuan, Hon; Yang, Jer Ren; Shiojiri, Makoto; Chen, Miin Jang

2009-04-22

This study demonstrates amplified spontaneous emission (ASE) of the ultraviolet (UV) electroluminescence (EL) from ZnO at lambda~380 nm in the n-ZnO/ZnO nanodots-SiO(2) composite/p- Al(0.12)Ga(0.88)N heterojunction light-emitting diode. A SiO(2) layer embedded with ZnO nanodots was prepared on the p-type Al(0.12)Ga(0.88)N using spin-on coating of SiO(2) nanoparticles followed by atomic layer deposition (ALD) of ZnO. An n-type Al-doped ZnO layer was deposited upon the ZnO nanodots-SiO(2) composite layer also by the ALD technique. High-resolution transmission electron microscopy (HRTEM) reveals that the ZnO nanodots embedded in the SiO(2) matrix have diameters of 3-8 nm and the wurtzite crystal structure, which allows the transport of carriers through the thick ZnO nanodots-SiO(2) composite layer. The high quality of the n-ZnO layer was manifested by the well crystallized lattice image in the HRTEM picture and the low-threshold optically pumped stimulated emission. The low refractive index of the ZnO nanodots-SiO(2) composite layer results in the increase in the light extraction efficiency from n-ZnO and the internal optical feedback of UV EL into n-ZnO layer. Consequently, significant enhancement of the UV EL intensity and super-linear increase in the EL intensity, as well as the spectral narrowing, with injection current were observed owing to ASE in the n-ZnO layer.

RNA interference targeting carbohydrate sulfotransferase 3 diminishes macrophage accumulation, inhibits MMP-9 expression and promotes lung recovery in murine pulmonary emphysema.

PubMed

Kai, Yoshiro; Tomoda, Koichi; Yoneyama, Hiroyuki; Yoshikawa, Masanori; Kimura, Hiroshi

2015-12-09

Chondroitin sulfate proteoglycans are an important mediators in inflammation and leukocyte trafficking. However, their roles in pulmonary emphysema have not been explored. In a murine model of elastase-induced pulmonary emphysema, we found increased carbohydrate sulfotransferase 3 (CHST3), a specific enzyme that synthesizes chondroitin 6-sulfate proteoglycan (C6SPG). To elucidate the role of C6SPG, we investigated the effect of small interfering RNA (siRNA) targeting CHST3 that inhibits C6SPG-synthesis on the pathogenesis of pulmonary emphysema. Mice were intraperitoneally injected with CHST3 siRNA or negative control siRNA on day0 and 7 after intratracheal instillation of elastase. Histology, respiratory function, glycosaminoglycans (GAGs) content, bronchoalveolar lavage (BAL), elastin staining and gene expressions of tumor necrosis factor (TNF)-α and matrix metalloproteinase (MMP)-9 mRNA were evaluated on day7 and/or day21. CHST3 mRNA increased at day 7 and decreased thereafter in lung. CHST3 siRNA successfully inhibited the expression of CHST3 mRNA throughout the study and this was associated with significant reduction of GAGs and C6SPG. Airway destruction and respiratory function were improved by the treatment with CHST3 siRNA. CHST3 siRNA reduced the number of macrophages both in BAL and lung parenchyma and also suppressed the increased expressions of TNF-α and MMP-9 mRNA. Futhermore, CHST3 siRNA improved the reduction of the elastin in the alveolar walls. CHST3 siRNA diminishes accumulation of excessive macrophages and the mediators, leading to accelerate the functional recovery from airway damage by repair of the elastin network associated with pulmonary emphysema.

Influence of the transition region between p- and n-type polycrystalline silicon passivating contacts on the performance of interdigitated back contact silicon solar cells

NASA Astrophysics Data System (ADS)

Reichel, Christian; Müller, Ralph; Feldmann, Frank; Richter, Armin; Hermle, Martin; Glunz, Stefan W.

2017-11-01

Passivating contacts based on thin tunneling oxides (SiOx) and n- and p-type semi-crystalline or polycrystalline silicon (poly-Si) enable high passivation quality and low contact resistivity, but the integration of these p+/n emitter and n+/n back surface field junctions into interdigitated back contact silicon solar cells poses a challenge due to high recombination at the transition region from p-type to n-type poly-Si. Here, the transition region was created in different configurations—(a) p+ and n+ poly-Si regions are in direct contact with each other ("pn-junction"), using a local overcompensation (counterdoping) as a self-aligning process, (b) undoped (intrinsic) poly-Si remains between the p+ and n+ poly-Si regions ("pin-junction"), and (c) etched trenches separate the p+ and n+ poly-Si regions ("trench")—in order to investigate the recombination characteristics and the reverse breakdown behavior of these solar cells. Illumination- and injection-dependent quasi-steady state photoluminescence (suns-PL) and open-circuit voltage (suns-Voc) measurements revealed that non-ideal recombination in the space charge regions with high local ideality factors as well as recombination in shunted regions strongly limited the performance of solar cells without a trench. In contrast, solar cells with a trench allowed for open-circuit voltage (Voc) of 720 mV, fill factor of 79.6%, short-circuit current (Jsc) of 41.3 mA/cm2, and a conversion efficiencies (η) of 23.7%, showing that a lowly conducting and highly passivating intermediate layer between the p+ and n+ poly-Si regions is mandatory. Independent of the configuration, no hysteresis was observed upon multiple stresses in reverse direction, indicating a controlled and homogeneously distributed breakdown, but with different breakdown characteristics.

Electrodepositing behaviors and properties of nano Fe-Ni-Cr/SiC composite coatings from trivalent chromium baths containing compound carboxylate-urea system.

PubMed

He, Xinkuai; Hou, Bailong; Cai, Youxing; Li, Chen; Jiang, Yumei; Wu, Luye

2013-06-01

The nano Fe-Ni-Cr/SiC composite coatings were prepared using pulse electrodeposition method from trivalent chromium baths containing compound carboxylate-urea system and nano SiC in ultrasonic field. The effects of the carboxylate-urea system on the nano Fe-Ni-Cr/SiC composite coatings have been investigated. These results indicated that the SiC and Cr contents and the thickness of the Fe-Ni-Cr/SiC composite coatings could be obviously improved by the compound carboxylate-urea system. The steady-state polarization curves showed that the hydrogen evolution reaction (HER) could be significantly inhibited by the compound carboxylate-urea system, which was benefit to increase the SiC and Cr contents and the thickness of the composite coatings. The cyclic voltammetry (CV) curves showed that the cathodic polarization of the matrix metal ions could be increased in the bath containing the compound carboxylate-urea system. Thus, a compact Fe-Ni-Cr/SiC composite coating could be obtained using this technique. The surface morphology of the Fe-Ni-Cr/SiC composite coatings checked with the scanning electron micrographs (SEM) showed that the surface smoothness could be also improved and the microcracks and pinholes could be decreased due to the presence of the compound carboxylate-urea system. The phase composition of the as-posited coating was measured by the X-ray diffraction (XRD). XRD data showed that the as-posited coating was Fe-Ni-Cr/SiC composite coating. The chemical composition of the coating was investigated by energy dispersive spectrum (EDS) analysis. The result showed the functional Fe-Ni-Cr/SiC composite coatings with 4.1 wt.% SiC and 25.1 wt.% Cr, and 23.9 microm thickness were obtained in this study, which had best corrosion resistance according to the results of the typical potentiodynamic polarization curves of the Fe-Ni-Cr/SiC composite coatings.

Maitotoxin Is a Potential Selective Activator of the Endogenous Transient Receptor Potential Canonical Type 1 Channel in Xenopus laevis Oocytes

PubMed Central

Flores, Pedro L.; Rodríguez, Emma; Zapata, Estrella; Carbó, Roxana; Farías, José María; Martínez, Martín

2017-01-01

Maitotoxin (MTX) is the most potent marine toxin known to date. It is responsible for a particular human intoxication syndrome called ciguatera fish poisoning (CFP). Several reports indicate that MTX is an activator of non-selective cation channels (NSCC) in different cell types. The molecular identity of these channels is still an unresolved topic, and it has been proposed that the transient receptor potential (TRP) channels are involved in this effect. In Xenopus laevis oocytes, MTX at picomolar (pM) concentrations induces the activation of NSCC with functional and pharmacological properties that resemble the activity of TRP channels. The purpose of this study was to characterize the molecular identity of the TRP channel involved in the MTX response, using the small interference RNA (siRNA) approach and the two-electrode voltage-clamp technique (TEVC). The injection of a specifically designed siRNA to silence the transient receptor potential canonical type 1 (TRPC1) protein expression abolished the MTX response. MTX had no effect on oocytes, even at doses 20-fold higher compared to cells without injection. Total mRNA and protein levels of TRPC1 were notably diminished. The TRPC4 siRNA did not change the MTX effect, even though it was important to note that the protein level was reduced by the silencing of TRPC4. Our results suggest that MTX could be a selective activator of TRPC1 channels in X. laevis oocytes and a useful pharmacological tool for further studies on these TRP channels. PMID:28672825

Maitotoxin Is a Potential Selective Activator of the Endogenous Transient Receptor Potential Canonical Type 1 Channel in Xenopus laevis Oocytes.

PubMed

Flores, Pedro L; Rodríguez, Emma; Zapata, Estrella; Carbó, Roxana; Farías, José María; Martínez, Martín

2017-06-25

Maitotoxin (MTX) is the most potent marine toxin known to date. It is responsible for a particular human intoxication syndrome called ciguatera fish poisoning (CFP). Several reports indicate that MTX is an activator of non-selective cation channels (NSCC) in different cell types. The molecular identity of these channels is still an unresolved topic, and it has been proposed that the transient receptor potential (TRP) channels are involved in this effect. In Xenopus laevis oocytes, MTX at picomolar (pM) concentrations induces the activation of NSCC with functional and pharmacological properties that resemble the activity of TRP channels. The purpose of this study was to characterize the molecular identity of the TRP channel involved in the MTX response, using the small interference RNA (siRNA) approach and the two-electrode voltage-clamp technique (TEVC). The injection of a specifically designed siRNA to silence the transient receptor potential canonical type 1 (TRPC1) protein expression abolished the MTX response. MTX had no effect on oocytes, even at doses 20-fold higher compared to cells without injection. Total mRNA and protein levels of TRPC1 were notably diminished. The TRPC4 siRNA did not change the MTX effect, even though it was important to note that the protein level was reduced by the silencing of TRPC4. Our results suggest that MTX could be a selective activator of TRPC1 channels in X. laevis oocytes and a useful pharmacological tool for further studies on these TRP channels.

A Laboratory Railgun for Terminal Ballistics and Arc Armature Research Studies

DTIC Science & Technology

1987-06-01

Projectile Velocity Profile 3000 2500 - 2000 U.4J 500 0 1000 -Bank Energy - 4.5 MJ Rail Height - 3 cm Rail Thickness - I cm Injection Vel . - 300 rn/s...1250 Rail Height - 3 cm Rail Thickness - i cm Injection Vel . - 300 m/s 1000 c 750 L U 500 250 0 I I 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Time. ms Figure 2.10... Vel . - 300 m/s L/R - 5 ms U S200 L ISO C- Si i5 to-000 50 0 0 2 3 Position Wm) Figure 2.11. Baseline Design Pressure Profile barrel length to