Fabrication and Characterization of a Micro Methanol Sensor Using the CMOS-MEMS Technique

PubMed Central

Fong, Chien-Fu; Dai, Ching-Liang; Wu, Chyan-Chyi

2015-01-01

A methanol microsensor integrated with a micro heater manufactured using the complementary metal oxide semiconductor (CMOS)-microelectromechanical system (MEMS) technique was presented. The sensor has a capability of detecting low concentration methanol gas. Structure of the sensor is composed of interdigitated electrodes, a sensitive film and a heater. The heater located under the interdigitated electrodes is utilized to provide a working temperature to the sensitive film. The sensitive film prepared by the sol-gel method is tin dioxide doped cadmium sulfide, which is deposited on the interdigitated electrodes. To obtain the suspended structure and deposit the sensitive film, the sensor needs a post-CMOS process to etch the sacrificial silicon dioxide layer and silicon substrate. The methanol senor is a resistive type. A readout circuit converts the resistance variation of the sensor into the output voltage. The experimental results show that the methanol sensor has a sensitivity of 0.18 V/ppm. PMID:26512671

Ethanol microsensors with a readout circuit manufactured using the CMOS-MEMS technique.

PubMed

Yang, Ming-Zhi; Dai, Ching-Liang

2015-01-14

The design and fabrication of an ethanol microsensor integrated with a readout circuit on-a-chip using the complementary metal oxide semiconductor (CMOS)-microelectro -mechanical system (MEMS) technique are investigated. The ethanol sensor is made up of a heater, a sensitive film and interdigitated electrodes. The sensitive film is tin dioxide that is prepared by the sol-gel method. The heater is located under the interdigitated electrodes, and the sensitive film is coated on the interdigitated electrodes. The sensitive film needs a working temperature of 220 °C. The heater is employed to provide the working temperature of sensitive film. The sensor generates a change in capacitance when the sensitive film senses ethanol gas. A readout circuit is used to convert the capacitance variation of the sensor into the output frequency. Experiments show that the sensitivity of the ethanol sensor is 0.9 MHz/ppm.

Sol-Gel Zinc Oxide Humidity Sensors Integrated with a Ring Oscillator Circuit On-a-Chip

PubMed Central

Yang, Ming-Zhi; Dai, Ching-Liang; Wu, Chyan-Chyi

2014-01-01

The study develops an integrated humidity microsensor fabricated using the commercial 0.18 μm complementary metal oxide semiconductor (CMOS) process. The integrated humidity sensor consists of a humidity sensor and a ring oscillator circuit on-a-chip. The humidity sensor is composed of a sensitive film and branch interdigitated electrodes. The sensitive film is zinc oxide prepared by sol-gel method. After completion of the CMOS process, the sensor requires a post-process to remove the sacrificial oxide layer and to coat the zinc oxide film on the interdigitated electrodes. The capacitance of the sensor changes when the sensitive film adsorbs water vapor. The circuit is used to convert the capacitance of the humidity sensor into the oscillation frequency output. Experimental results show that the output frequency of the sensor changes from 84.3 to 73.4 MHz at 30 °C as the humidity increases 40 to 90 %RH. PMID:25353984

Effects of Ether vs. Ester Linkage on Lipid Bilayer Structure and Water Permeability

PubMed Central

Guler, S. Deren; Ghosh, D. Dipon; Pan, Jianjun; Matthai, John C.; Zeidel, Mark L.; Nagle, John F.; Tristram-Nagle, Stephanie

2009-01-01

The structure and water permeability of bilayers composed of the ether linked lipid, dihexadecylphosphatidylcholine (DHPC), were studied and compared with the ester linked lipid, dipalmitoylphosphaditdylcholine (DPPC). Wide angle x-ray scattering on oriented bilayers in the fluid phase indicate that the area per lipid A is slightly larger for DHPC than for DPPC. Low angle x-ray scattering yields A=65.1Å2 for DHPC at 48°C. LAXS data provide the bending modulus, KC=4.2×10−13erg, and the Hamaker parameter H=7.2×10−14erg for the van der Waals attractive interaction between neighboring bilayers. For the low temperature phases with ordered hydrocarbon chains, we confirm the transition from a tilted Lß’ gel phase to an untilted, interdigitated LßI phase as the sample hydrates at 20°C. Our measurement of water permeability, Pf=0.022 cm/s at 48 °C for fluid phase DHPC is slightly smaller than that of DPPC, (Pf=0.027 cm/s) at 50 °C, consistent with our triple slab theory of permeability. PMID:19416724

Electrospun bismuth ferrite nanofibers for potential applications in ferroelectric photovoltaic devices.

PubMed

Fei, Linfeng; Hu, Yongming; Li, Xing; Song, Ruobing; Sun, Li; Huang, Haitao; Gu, Haoshuang; Chan, Helen L W; Wang, Yu

2015-02-18

Bismuth ferrite (BFO) nanofibers were synthesized via a sol-gel-based electrospinning process followed by thermal treatment. The influences of processing conditions on the final structure of the samples were investigated. Nanofibers prepared under optimized conditions were found to have a perovskite structure with good quality of crystallization and free of impurity phase. Ferroelectric and piezoelectric responses were obtained from individual nanofiber measured on a piezoelectric force microscope. A prototype photovoltaic device using laterally aligned BFO nanofibers and interdigital electrodes was developed and its performance was examined on a standard photovoltaic system. The BFO nanofibers were found to exhibit an excellent ferroelectric photovoltaic property with the photocurrent several times larger than the literature data obtained on BFO thin films.

All-solid-state flexible ultrathin micro-supercapacitors based on graphene.

PubMed

Niu, Zhiqiang; Zhang, Li; Liu, Lili; Zhu, Bowen; Dong, Haibo; Chen, Xiaodong

2013-08-07

Flexible, compact, ultrathin and all-solid-state micro-supercapacitors are prepared by coating H₃PO₄/PVA gel electrolyte onto micro-patterned rGO interdigitated electrodes prepared by combining photolithography with selective electrophoretic deposition. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermodynamic and fluorescence studies of the underlying factors in benzyl alcohol-induced lipid interdigitated phase.

PubMed

Chen, C H; Hoye, K; Roth, L G

1996-09-15

To further investigate factors contributing to the action of alcohol in the solute-induced lipid interdigitation phase, thermodynamic and fluorescence polarization measurements were carried out to study the interaction of benzyl alcohol with dipalmitoyl phosphatidylcholine bilayer vesicles. The obtained results were compared with those previously reported for ethanol and cyclohexanol (L. G. Roth and C-H. Chen, Arch. Biochem. Biophys. 296, 207, 1992). Similar to ethanol, benzyl alcohol was found to exhibit a biphasic effect on the enthalpy (delta Hm) and the temperature (tm) of the lipid-phase transition and the steady-state fluorescence polarization (P) monitored by 1,6-diphenyl-1,3,5-hexatriene. At a total concentration of benzyl alcohol < 30 mg/ml (the alcohol concentration in lipid phase < 21 mg/ml), benzyl alcohol was found to exhibit large increases in delta Hm and P, which were correlated with the formation of a lipid interdigitated phase, as evidenced by reported X-ray diffraction data. Combining the results with benzyl alcohol and ethanol suggested that simultaneously large changes in delta Hm and P can be used as an indication of the occurrence of a solute-induced lipid interdigitated phase. The overall interacting force in the formation of this lipid phase, as derived from the interactions of the hydroxyl portion of an alcohol with the lipid phosphate head group and the hydrophobic portion of an alcohol with the lipid hydrocarbon chains, may or may not be dominated by hydrophobic interaction. Although lipid/water partition coefficients and the contribution of hydrophobic interaction to the overall interacting force were comparable between benzyl alcohol and cyclohexanol, benzyl alcohol induced lipid interdigitated phase, but not for cyclohexanol. This was due to the ability of benzyl alcohol to be more effective than cyclohexanol in simultaneously interacting with the phosphate head group and the hydrocarbon chains of lipid.

Dynamic response of a lenticular microlens array using a polyvinyl chloride gel

NASA Astrophysics Data System (ADS)

Li, Xiaolong; Zhou, Zuowei; Ren, Hongwen

2017-12-01

We prepared a lenticular microlens array (LMA) using a polyvinyl chloride (PVC) gel and an interdigitated electrode. By applying a DC voltage to the electrode, the surface of the PVC gel can be waved with an LMA character. When the voltage is removed, the wavy PVC gel can recover its flat surface gradually. With the aid of a polarity-inverted voltage, the recovering time can be largely reduced. The LMA can present a stable dynamic response when it is repetitively impacted by a pulse voltage. The experimental results are given, and the mechanism of reducing the dynamic response time is explained. Our LMA with improved response time has potential applications in sensing, beam steering, biometrics, and displays.

New ZnO-Based Glass Ceramic Sensor for H2 and NO2 Detection

PubMed Central

Afify, Ahmed S.; Ataalla, Mohamed

2017-01-01

In this study, a glass ceramic with a nominal composition 58ZnO:4Bi2O3:4WO3:33.3B2O3 was synthesized by melt quenching technique. A gas sensor was then manufactured using a ZnO sol-gel phase as a permanent binder of the glass–ceramic to an alumina substrate having interdigitated electrodes. The film sensitivity towards humidity, NH3, H2 and NO2 was studied at different temperatures. X-ray diffraction technique (XRD), field emission- scanning electron microscopy (FE-SEM) and differential thermal analysis (DTA) were used to characterize the prepared material. Though the response in the sub-ppm NO2 concentration range was not explored, the observed results are comparable with the latest found in the literature. PMID:29099781

The vesosome-- a multicompartment drug delivery vehicle.

PubMed

Kisak, E T; Coldren, B; Evans, C A; Boyer, C; Zasadzinski, J A

2004-01-01

Assembling structures to divide space controllably and spontaneously into subunits at the nanometer scale is a significant challenge, although one that biology has solved in two distinct ways: prokaryotes and eukaryotes. Prokaryotes have a single compartment delimited by one or more lipid-protein membranes. Eukaryotes have nested-membrane structures that provide internal compartments--such as the cell nucleus and cell organelles in which specialized functions are carried out. We have developed a simple method of creating nested bilayer compartments in vitro via the "interdigitated" bilayer phase formed by adding ethanol to a variety of saturated phospholipids. At temperatures below the gel-liquid crystalline transition, T(m), the interdigitated lipid-ethanol sheets are rigid and flat; when the temperature is raised above T(m), the sheets become flexible and close on themselves and the surrounding solution to form closed compartments. During this closure, the sheets can entrap other vesicles, biological macromolecules, or colloidal particles. The result is efficient and spontaneous encapsulation without disruption of even fragile materials to form biomimetic nano-environments for possible use in drug delivery, colloidal stabilization, or as microreactors. The vesosome structure can take full advantage of the 40 years of progress in liposome development including steric stabilization, pH loading of drugs, and intrinsic biocompatibility. However, the multiple compartments of the vesosome give better protection to the interior contents in serum, leading to extended release of model compounds in comparison to unilamellar liposomes.

Fabrication and characterization of polyaniline/PVA humidity microsensors.

PubMed

Yang, Ming-Zhi; Dai, Ching-Liang; Lin, Wei-Yi

2011-01-01

This study presents the fabrication and characterization of a humidity microsensor that consists of interdigitated electrodes and a sensitive film. The area of the humidity microsensor is about 2 mm(2). The sensitive film is polyaniline doping polyvinyl alcohol (PVA) that is prepared by the sol-gel method, and the film has nanofiber and porous structures that help increase the sensing reaction. The commercial 0.35 μm Complimentary Metal Oxide Semiconductor (CMOS) process is used to fabricate the humidity microsensor. The sensor needs a post-CMOS process to etch the sacrificial layer and to coat the sensitive film on the interdigitated electrodes. The sensor produces a change in resistance as the polyaniline/PVA film absorbs or desorbs vapor. Experimental results show that the sensitivity of the humidity sensor is about 12.6 kΩ/%RH at 25 °C.

A bulk micromachined lead zinconate titanate cantilever energy harvester with inter-digital IrO(x) electrodes.

PubMed

Park, Jongcheol; Park, Jae Yeong

2013-10-01

A piezoelectric vibration energy harvester with inter-digital IrO(x) electrode was developed by using silicon bulk micromachining technology. Most PZT cantilever based energy harvesters have utilized platinum electrode material. However, the PZT fatigue characteristics and adhesion/delamination problems caused by the platinum electrode might be serious problem in reliability of energy harvester. To address these problems, the iridium oxide was newly applied. The proposed energy harvester was comprised of bulk micromachined silicon cantilever with 800 x 1000 x 20 microm3, which having a silicon supporting membrane, sol-gel-spin coated Pb(Zr52, Ti48)O3 thin film, and sputtered inter-digitally shaped IrO(x) electrodes, and silicon inertial mass with 1000 x 1000 x 500 microm3 to adjust its resonant frequency. The fabricated energy harvester generated 1 microW of electrical power to 470 komega of load resistance and 1.4 V(peak-to-peak) from a vibration of 0.4 g at 1.475 kHz. The corresponding power density was 6.25 mW x cm(-3) x g(-2). As expected, its electrical failure was significantly improved.

Two-phase interdigitated microelectrode arrays for electrokinetic transport of microparticles

NASA Astrophysics Data System (ADS)

Bligh, Mathew; Stanley, Kevin G.; Hubbard, Ted; Kujath, Marek

2008-05-01

In this paper, we demonstrate long-range particle transport using linear two-phase interdigitated arrays with electrodes of equal size but with asymmetric spacing between them. We report net motion of 6 µm polystyrene spheres in an aqueous electrolyte and characterize the dependence of particle velocity on frequency, potential and phase, and show consistency with previous experiments that involved four-phase arrays producing AC electroosmotic and dielectrophoretic forces. We explore the effect of increasing the asymmetry of the electrode spacing and show that this decreases the performance of the array. We also examine the effect of increasing the overall scale of the array while maintaining geometric proportions and particle size and report that this also decreases the performance. We compare our results to previous analytical theoretical predictions and find general agreement.

Self-Assembly, Supramolecular Organization, and Phase Behavior of L-Alanine Alkyl Esters (n = 9-18) and Characterization of Equimolar L-Alanine Lauryl Ester/Lauryl Sulfate Catanionic Complex.

PubMed

Sivaramakrishna, D; Swamy, Musti J

2015-09-08

A homologous series of l-alanine alkyl ester hydrochlorides (AEs) bearing 9-18 C atoms in the alkyl chain have been synthesized and characterized with respect to self-assembly, supramolecular structure, and phase transitions. The CMCs of AEs bearing 11-18 C atoms were found to range between 0.1 and 10 mM. Differential scanning calorimetric (DSC) studies showed that the transition temperatures (Tt), enthalpies (ΔHt) and entropies (ΔSt) of AEs in the dry state exhibit odd-even alternation, with the odd-chain-length compounds having higher Tt values, but the even-chain-length homologues showing higher values of ΔHt and ΔSt. In DSC measurements on hydrated samples, carried out at pH 5.0 and pH 10.0 (where they exist in cationic and neutral forms, respectively), compounds with 13-18 C atoms in the alkyl chain showed sharp gel-to-liquid crystalline phase transitions, and odd-even alternation was not seen in the thermodynamic parameters. The molecular structure, packing properties, and intermolecular interactions of AEs with 9 and 10 C atoms in the alkyl chain were determined by single crystal X-ray diffraction, which showed that the alkyl chains are packed in a tilted interdigitated bilayer format. d-Spacings obtained from powder X-ray diffraction studies exhibited a linear dependence on the alkyl chain length, suggesting that the other AEs also adopt an interdigitated bilayer structure. Turbidimetric, fluorescence spectroscopic, and isothermal titration calorimetric (ITC) studies established that in aqueous dispersions l-alanine lauryl ester hydrochloride (ALE·HCl) and sodium dodecyl sulfate (SDS) form an equimolar complex. Transmission electron microscopic and DSC studies indicate that the complex exists as unilamellar liposomes, which exhibit a sharp phase transition at ∼39 °C. The aggregates were disrupted at high pH, suggesting that the catanionic complex would be useful to develop a base-labile drug delivery system. ITC studies indicated that ALE·HCl forms a strong complex with DNA, suggesting that the AEs may find use in DNA therapeutics as well.

Monolithic GaAs dual-gate FET phase shifter

NASA Astrophysics Data System (ADS)

Kumar, M.; Subbarao, S. N.; Menna, R.

1981-09-01

The objective of this program is to develop a monolithic GaAs dual-gate FET phase shifter, operating over the 4- to 8-GHz frequency band and capable of a continuously programmable phase shift from 0 deg through N times 360 deg where N is an integer. The phase shift is to be controllable to within +3 deg. This phase shifter will be capable of delivering an output power up to 0 dBm with an input and output VSWR of less than 1.5:1. Progress 1: The photomask of a 0 to 90 deg monolithic GaAs dual-gate FET phase shifter has been procured, and we are in the process of fabricating the phase shifter. 2: We have designed and fabricated a 50 ohm, 4-line interdigitated coupler. Also, we have designed and fabricated a 25-ohm, 6-line interdigitated coupler. The performance of both couplers agrees quite well with the theoretical results. Technical Problems: there was no major problem during this period.

Investigation of phase transitions of saturated phosphocholine lipid bilayers via molecular dynamics simulations.

PubMed

Khakbaz, Pouyan; Klauda, Jeffery B

2018-08-01

Lipid bilayers play an important role in biological systems as they protect cells against unwanted chemicals and provide a barrier for material inside a cell from leaking out. In this paper, nearly 30 μs of molecular dynamics (MD) simulations were performed to investigate phase transitions of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dipalmitoyl-sn-glycero-phosphocholine (DPPC) lipid bilayers from the liquid crystalline (L α ) to the ripple (P β ) and to the gel phase (L β ). Our MD simulations accurately predict the main transition temperature for the single-component bilayers. A key focus of this work is to quantify the structure of the P β phase for DMPC and compare with measures from x-ray experiments. The P β major arm has similar structure to that of the L β , while the thinner minor arm has interdigitated chains and the transition region between these two regions has large chain splay and disorder. At lower temperatures, our MD simulations predict the formation of the L β phase with tilted fatty acid chains. The P β and L β phases are studied for mixtures of DMPC and DPPC and compare favorably with experiment. Overall, our MD simulations provide evidence for the relevancy of the CHARMM36 lipid force field for structures and add to our understanding of the less-defined P β phase. Copyright © 2018 Elsevier B.V. All rights reserved.

[Modified gloving technique for vacuum therapy in the hand].

PubMed

Polykandriotis, E; Kneser, U; Kopp, J; Horch, R E

2006-04-01

During the last 10 years sub-atmospheric pressure dressings (Topical Negative Pressure Therapy = TNP) has become a well accepted standard therapeutic modality in the management of acute and chronic wounds. However, in the hand and the fingers TNP treatment is not as an established method as elsewhere in the body. This is mostly due to difficulties in the technique of sealing wounds near the interdigital folds, especially when the interdigital folds are affected themselves. Over a period of 36 months we treated 9 extensive open wounds of the hand with the TNP dressing procedure. To optimize the effective sealing procedure several methods of closure were applied: sterile vinyl gloves, split V.A.C. gel-straps and the "Sandwich"-principle. In all cases we were able to achieve a tight vacuum sealing with the use of our vinyl or latex free surgical glove as an aid to cover the interdigital spaces. There was a rapid and complete remission of the symptoms in terms of edema, redness, tenderness and range of motion. The indication spectrum encompassed infection control, temporary coverage of exposed bone or tendons, intermittent irrigation with local antiseptics as well as wound preconditioning before skin grafting or flap coverage. For the definite closure or coverage a second operation was necessary in all cases. The TNP-dressing can be securely achieved even in wounds encompassing the interdigital folds or adjacent to the in digital spaces with a modified surgical gloving technique to aid the standard sealing foil. It is a suitable principle for the management of severe hand infections with a reduction of clinical symptoms, reduction of the frequency of dressing changes compared to open approaches and a significant amelioration in the quality of life both for patients and health care personnel.

Low-cost flexible supercapacitors based on laser reduced graphene oxide supported on polyethylene terephthalate substrate

NASA Astrophysics Data System (ADS)

Ghoniem, Engy; Mori, Shinsuke; Abdel-Moniem, Ahmed

2016-08-01

A controlled high powered CO2 laser system is used to reduce and pattern graphene oxide (GO) film supported onto a flexible polyethylene terephthalate (PET) substrate. The laser reduced graphene oxide (rGO) film is characterized and evaluated electrochemically in the absence and presence of an overlying anodicaly deposited thin film of pseuodcapactive MnO2 as electrodes for supercapacitor applications using aqueous electrolyte. The laser treatment of the GO film leads to an overlapped structure of defective multi-layer rGO sheets with an electrical conductivity of 273 S m-1. The rGO and MnO2/rGO electrodes exhibit specific capacitance in the range of 82-107 and 172-368 Fg-1 at applied current range of 0.1-1.0 mA cm-2 and retain 98 and 95% of their initial capacitances after 2000 cycles at a current density of 1.0 mA cm-2, respectively. Also, the rGO is assigned as an electrode material for flexible conventionally stacked and interdigitated in-plane supercapacitor structures using gel electrolyte. Three electrode architectures of 2, 4, and 6 sub-electrodes are studied for the interdigital in-plane design. The device with interdigital 6 sub-electrodes architecture I-PS(6) delivers power density of 537.1 Wcm-3 and an energy density of 0.45 mWh cm-3.

Solvent induced modifications to fiber nanostructure and morphology for 12HSA molecular gels

NASA Astrophysics Data System (ADS)

Gao, Jie

Molecular organogels are thermo reversible quasi-solid materials, which are formed by low molecular weight organogelators (LMOGs) undergoing supramolecular aggregation via non-covalent interactions, forming a three-dimensional fibrillar network. Numerous applications of molecular organogels are been investigated as edible oils, drug release matrices and personal care products. The chemistry of the organic phase (i.e., solvent) influences every level of structure in organogels. Different solvents induce LMOG to assemble into "crystal like" fibers, which have more than one crystal form, lamellar arrangement and domain size. Differences in these solid states are known to affect the macroscopic properties of the gel, including critical gelator concentration (CGC), melting point, melting enthalpy and opacity.12-hydroxystearic acid (12HSA) was examined in several classes of organic solvents with different function groups. These gels, sols or precipitates were analyzed using a series of techniques including: powder x-ray diffraction (XRD), differential scanning calorimetry (DSC), fourier-transform infrared spectroscopy (FT-IR), pulsed nuclear magnetic resonance spectroscopy (pNMR) and microscopy. Specifically, certain solvents caused 12HSA to self-assemble into a triclinic parallel polymorphic form with subcell spacing of ~4.6, 3.9, and 3.8 A and an interdigitated unit cell with a lamellar arrangement (38~44 A). This polymorphic form corresponded to a less effective sphereultic supramolecular crystalline network, which immobilizes solvents at CGC greater than 1.5 wt %. The other group of solvents induce a hexagonal subcell spacing (i.e., unit sub cell spacing ~4.1 A) and are arranged in a multi lamellar fashion with a unit cell greater than the bimolecular length of 12HSA (~54 A).This polymorphic form corresponds to fibrillar aggregates with a CGC less than 1 wt %.

Phase II trial evaluating the feasibility of interdigitating folfox with chemoradiotherapy in locally advanced and metastatic rectal cancer.

PubMed

Michael, M; Chander, S; McKendrick, J; MacKay, J R; Steel, M; Hicks, R; Heriot, A; Leong, T; Cooray, P; Jefford, M; Zalcberg, J; Bressel, M; McClure, B; Ngan, S Y

2014-11-11

Patients (pts) with metastatic rectal cancer and symptomatic primary, require local and systemic control. Chemotherapy used during chemoradiotherapy (CRT) is adequate for radiosensitisation, but suboptimal for systemic control. The aim of this phase II study was to assess tolerability, local/systemic benefits, of a novel regimen delivering interdigitating intensive chemotherapy with radical CRT. Eligible pts had untreated synchronous symptomatic primary/metastatic rectal cancer. A total of 12 weeks of treatment with split-course pelvic CRT (total 50.4 Gy with concurrent oxaliplatin and 5-FU infusion) alternating with FOLFOX chemotherapy. All pts staged with CT, MRI and FDG-PET pre and post treatment. Twenty-six pts were treated. Rectal primary MRI stage: T3 81% and T4 15%. Liver metastases in 81%. Twenty-four pts (92%) completed the 12-week regimen. All patients received planned RT dose, and for both agents over 88% of patients achieved a relative dose intensity of >75%. Grade 3 toxicities: neutropenia 23%, diarrhoea 15%, and radiation skin reaction 12%. Grade 4 toxicity: neutropenia 15%. FDG-PET metabolic response rate for rectal primary 96%, and for metastatic disease 60%. Delivery of interdigitating chemotherapy with radical CRT was feasible to treat both primary and metastatic rectal cancer. High completion and response rates were encouraging.

Capacitance Variation Induced by Microfluidic Two-Phase Flow across Insulated Interdigital Electrodes in Lab-On-Chip Devices

PubMed Central

Dong, Tao; Barbosa, Cátia

2015-01-01

Microfluidic two-phase flow detection has attracted plenty of interest in various areas of biology, medicine and chemistry. This work presents a capacitive sensor using insulated interdigital electrodes (IDEs) to detect the presence of droplets in a microchannel. This droplet sensor is composed of a glass substrate, patterned gold electrodes and an insulation layer. A polydimethylsiloxane (PDMS) cover bonded to the multilayered structure forms a microchannel. Capacitance variation induced by the droplet passage was thoroughly investigated with both simulation and experimental work. Olive oil and deionized water were employed as the working fluids in the experiments to demonstrate the droplet sensor. The results show a good sensitivity of the droplet with the appropriate measurement connection. This capacitive droplet sensor is promising to be integrated into a lab-on-chip device for in situ monitoring/counting of droplets or bubbles. PMID:25629705

Interdigital pair bonding for high frequency (20-50 MHz) ultrasonic composite transducers.

PubMed

Liu, R; Harasiewicz, K A; Foster, F S

2001-01-01

Interdigital pair bonding is a novel methodology that enables the fabrication of high frequency piezoelectric composites with high volume fractions of the ceramic phase. This enhancement in ceramic volume fraction significantly reduces the dimensional scale of the epoxy phase and increases the related effective physical parameters of the composite, such as dielectric constant and the longitudinal sound velocity, which are major concerns in the development of high frequency piezoelectric composites. In this paper, a method called interdigital pair bonding (IPB) is used to prepare 1-3 piezoelectric composite with a pitch of 40 microns, a kerf of 4 microns, and a ceramic volume fraction of 81%. The composites prepared in this fashion exhibited a very pure thickness-mode resonance up to a frequency of 50 MHz. Unlike the 2-2 piezoelectric composites with the same ceramic and epoxy scales developed earlier, the anticipated lateral modes between 50 to 100 MHz were not observed in the current 1-3 composites. The mechanisms for the elimination of the lateral modes at high frequency are discussed. The effective electromechanical coupling coefficient of the composite was 0.72 at a frequency of 50 MHz. The composites showed a high longitudinal sound velocity of 4300 m/s and a high clamped dielectric constant of 1111 epsilon 0, which will benefit the development of high frequency ultrasonic transducers and especially high frequency transducer arrays for medical imaging.

Cycle stability of the electrochemical capacitors patterned with vertically aligned carbon nanotubes in an LiPF6-based electrolyte.

PubMed

Chiou, Yi-Deng; Tsai, Dah-Shyang; Lam, Hoa Hung; Chang, Chuan-hua; Lee, Kuei-Yi; Huang, Ying-Sheng

2013-09-07

The miniature ultracapacitors, with interdigitated electrodes of vertically aligned carbon nanotubes (VACNTs) and an inter-electrode gap of 20 μm, have been prepared in the LiPF6 organic electrolyte with and without PVdF-HFP gel. PVdF-HFP between two opposing electrodes enhances the device reliability, but lessens its power performance because of the extra diffusion resistance. Also noteworthy are the gel influences on the cycle stability. When the applied voltage is 2.0 or 2.5 V, both the LiPF6 and the gel capacitors exhibit excellent stability, typified by a retention ratio of ≥95% after 10,000 cycles. Their coulombic efficiencies quickly rise up, and hold steady at 100%. Nonetheless, when the applied voltage is 3.5 or 4.0 V, the cycle stability deteriorates, since the negative electrode potential descends below 0.9 V (vs. Li), leading to electrolyte decomposition and SEI formation. For the LiPF6 capacitor, its retention ratio could be around 60% after 10,000 cycles and the coulombic efficiency of 100% is difficult to reach throughout its cycle life. On the other hand, the gel capacitor cycles energy with a much higher retention ratio, >80% after 10,000 cycles, and a better coulombic efficiency, even though electrolyte decomposition still occurs. We attribute the superior stability of the gel capacitor to its extra diffusion resistance which slows down the performance deterioration.

A micro oxygen sensor based on a nano sol-gel TiO2 thin film.

PubMed

Wang, Hairong; Chen, Lei; Wang, Jiaxin; Sun, Quantao; Zhao, Yulong

2014-09-03

An oxygen gas microsensor based on nanostructured sol-gel TiO2 thin films with a buried Pd layer was developed on a silicon substrate. The nanostructured titania thin films for O2 sensors were prepared by the sol-gel process and became anatase after heat treatment. A sandwich TiO2 square board with an area of 350 μm × 350 μm was defined by both wet etching and dry etching processes and the wet one was applied in the final process due to its advantages of easy control for the final structure. A pair of 150 nm Pt micro interdigitated electrodes with 50 nm Ti buffer layer was fabricated on the board by a lift-off process. The sensor chip was tested in a furnace with changing the O2 concentration from 1.0% to 20% by monitoring its electrical resistance. Results showed that after several testing cycles the sensor's output becomes stable, and its sensitivity is 0.054 with deviation 2.65 × 10(-4) and hysteresis is 8.5%. Due to its simple fabrication process, the sensor has potential for application in environmental monitoring, where lower power consumption and small size are required.

SU-E-T-306: Dosimetric Comparison of Leaf with Or Without Interdigitation in Multiple Brain Metastasis VMAT Treatment Planning

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

NONE

Purpose: To evaluate the effects of leaf with or without interdigitation in multiple brain metastasis volumetric modulated arc therapy (VMAT) plans. Methods: Twenty patients with 2 to 6 brain metastases of our hospital were retrospectively studied to be planned with dual arc VMAT using Monaco 3.3 TPS on the Elekta Synergy linear accelerator. The prescription dose of PTV was 60Gy/30 fractions. Two plans with or without leaf interdigitation were designed. The homogeneity index (HI), conformity index (CI), dose volume histograms (DVHs), monitor unit (MU), treatment time (T), the segments, the dose coverage of the target, were all evaluated. Results: Themore » plans with leaf interdigitation could achieve better CI (p<0.05) than without leaf interdigitation, while no significant difference were found in HI (p> 0.05) and the dose coverage of the target (p> 0.05).The MU,T, and the segments of the plan with leaf interdigitation were more than the plan without leaf interdigitation (p<0.05). There was no significant difference found in radiation dose of spinal cord, lenses and parotids, while the maximum dose of brain stem of leaf without interdigitation was higher than leaf with interdigitation (p< 0.05). It was worth noting that the areas of low dose regions with leaf interdigitation plan were much less than the without leaf interdigitation plan in the doublication planes (p< 0.05). Conclusion: This study shows that leaf with interdigitation has some advantages than leaf without interdigitation in multiple brain metastasis VMAT plans although the clinical relevance remains to be proven.« less

Finite-element analysis of scattering parameters of surface acoustic wave bandpass filter formed on barium titanate thin film

NASA Astrophysics Data System (ADS)

Timoshenko; Kalinchuk; Shirokov

2018-04-01

The frequency dependence of scattering parameters of interdigital surface acoustic wave transducers placed on ferroelectric barium titanate (BaTiO3) epitaxial film in c-phase coated over magnesium oxide has been studied using the finite-element method (FEM) approach along with the perfectly matched layer (PML) technique. The interdigital transducer which has a comb-like structure with aluminum electrodes excites the mechanical wave. The distance between the fingers allows tuning the frequency properties of the wave propagation. The magnesium oxide is taken as the substrate. The two-dimensional model of two-port surface acoustic wave filter is created to calculate scattering parameters and to show how to design the fixture in COMSOLTM. Some practical computational challenges of finite element modeling of SAW devices in COMSOLTM are shown. The effect of lattice misfit strain on acoustic properties of heterostructures of BaTiO3 epitaxial film in c-phase at room temperature is discussed in present article for two low-frequency surface acoustic resonances.

Polymerization speed and diffractive experiments in polymer network LC test cells

NASA Astrophysics Data System (ADS)

Braun, Larissa; Gong, Zhen; Habibpourmoghadam, Atefeh; Schafforz, Samuel L.; Wolfram, Lukas; Lorenz, Alexander

2018-02-01

Polymer-network liquid crystals (LCs), where the response properties of a LC can be enhanced by the presence of a porous polymer network, are investigated. In the reported experiments, liquid crystals were doped with a small amount (< 10%) of photo-curable acrylate monomers. Samples with surface grafted photoinitiators, dissolvable photoinitiators, and samples with both kinds of photoinitiators were prepared. Both conventional (planar electrodes) and diffractive (interdigitated electrodes) test cells were used. These samples were exposed with a UV light source and changes of their capacitance were investigated with an LCR meter during exposure. Due to the presence of the in-situ generated polymer network, the electro-optic response properties of photo cured samples were enhanced. For example, their continuous phase modulation properties led to more localized responses in samples with interdigitated electrodes, which caused suppression of selected diffraction orders in the diffraction patterns recorded in polymer network LC samples. Moreover, capacitance changes were investigated during photopolymerization of a blue phase LC.

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

Duan, J

Purpose: The aim of this work is to study the dosimetric impact of leaf interdigitation in prostate cancer dynamic IMRT treatment planning. Methods: Fifteen previously treated prostate cancer patients were replanned for dynamic IMRT (dMLC) with and without leaf interdigitation using Monaco 3.3 TPS on the Elekta Synergy linear accelerator. The prescription dose of PTV was 70Gy/35 fractions. Various dosimetric variables, such as PTV coverage, OAR sparing, delivery efficiency and optimization time, were evaluated for each plan. Results: Interdigitation did not improve the coverage, HI and CI for PTV. Regarding OARs, sparing was equivalent with and without interdigitation. Interdigitation shownmore » an increase in MUs and segments. It was worth noting that leaf interdigitation saved the optimization time. Conclusion: This study shows that leaf interdigitation does not improve plan quality when performing dMLC treatment plan for prostate cancer. However, it influences delivery efficiency and optimization time. Interdigitation may gain efficiency for dosimetrist when designing the prostate cancer dMLC plans.« less

Entropic Anomaly Observed in Lipid Polymorphisms Induced by Surfactant Peptide SP-B(1-25).

PubMed

Tran, Nhi; Kurian, Justin; Bhatt, Avni; McKenna, Robert; Long, Joanna R

2017-10-05

The N-terminal 25 amino-acid residues of pulmonary surfactant protein B (SP-B 1-25 ) induces unusual lipid polymorphisms in a model lipid system, 4:1 DPPC/POPG, mirroring the lipid composition of native pulmonary surfactant. It is widely suggested that SP-B 1-25 -induced lipid polymorphisms within the alveolar aqueous subphase provide a structural platform for rapid lipid adsorption to the air-water interface. Here, we characterize in detail the phase behavior of DPPC and POPG in hydrated lipid assemblies containing therapeutic levels of SP-B 1-25 using 2 H and 31 P solid state NMR spectroscopy. The appearance of a previously observed isotropic lipid phase is found to be highly dependent on the thermal cycling of the samples. Slow heating of frozen samples leads to phase separation of DPPC into a lamellar phase whereas POPG lipids interact with the peptide to form an isotropic phase at physiologic temperature. Rapid heating of frozen samples to room temperature leads to strongly isotropic phase behavior for both DPPC and POPG lipids, with DPPC in exchange between isotropic and interdigitated phases. 31 P T 2 relaxation times confirm the isotropic phase to be consistent with a lipid cubic phase. The observed phases exhibit thermal stability up to physiologic temperature (37 °C) and are consistent with the formation of a ripple phase containing a large number of peptide-induced membrane structural defects enabling rapid transit of lipids between lipid lamellae. The coexistance of a lipid cubic phase with interdigitated lipids suggests a specific role for the highly conserved N-terminus of SP-B in stabilizing this unusual lipid polymorphism.

Kinetics and dynamics of annealing during sub-gel phase formation in phospholipid bilayers

PubMed Central

Páli, Tibor; Bartucci, Rosa; Horváth, László I.; Marsh, Derek

1993-01-01

The saturation transfer electron spin resonance (STESR) spectra of spin-labeled phosphatidylcholine have been used to follow the kinetics of conversion from the gel phase to the sub-gel phase in aqueous bilayers of dipalmitoyl phosphatidylcholine. This is a simple, well-defined model system for lipid domain formation in membranes. The integrated intensity of the STESR spectrum from the chain-labeled lipid first increases and then decreases with time of incubation in the gel phase at 0°C. The first, more rapid phase of the kinetics is attributed to the conversion of germ nuclei to growth nuclei of the sub-gel phase. The increase in STESR intensity corresponds to the reduction in chain mobility of spin labels located in the gel phase at the boundaries of the growth nuclei and correlates with the increase in the diagnostic STESR line height ratios over this time range. The second, slower phase of the kinetics is attributed to growth of the domains of the sub-gel phase. The decrease in STESR intensity over this time regime corresponds to exclusion of the spin-labeled lipids from the tightly packed sub-gel phase and correlates quantitatively with calibrations of the spin label concentration dependence of the STESR intensity in the gel phase. The kinetics of formation of the sub-gel phase are consistent with the classical model for domain formation and growth. At 0°C, the half-time for conversion of germ nuclei to growth nuclei is ∼7.7 h and domain growth of the sub-gel phase is characterized by a rate constant of 0.025 h-1. The temperature dependence of the STESR spectra from samples annealed at 0°C suggests that the subtransition takes place via dissolution of sub-gel phase domains, possibly accompanied by domain fission. PMID:19431899

A Micro Oxygen Sensor Based on a Nano Sol-Gel TiO2 Thin Film

PubMed Central

Wang, Hairong; Chen, Lei; Wang, Jiaxin; Sun, Quantao; Zhao, Yulong

2014-01-01

An oxygen gas microsensor based on nanostructured sol-gel TiO2 thin films with a buried Pd layer was developed on a silicon substrate. The nanostructured titania thin films for O2 sensors were prepared by the sol-gel process and became anatase after heat treatment. A sandwich TiO2 square board with an area of 350 μm × 350 μm was defined by both wet etching and dry etching processes and the wet one was applied in the final process due to its advantages of easy control for the final structure. A pair of 150 nm Pt micro interdigitated electrodes with 50 nm Ti buffer layer was fabricated on the board by a lift-off process. The sensor chip was tested in a furnace with changing the O2 concentration from 1.0% to 20% by monitoring its electrical resistance. Results showed that after several testing cycles the sensor's output becomes stable, and its sensitivity is 0.054 with deviation 2.65 × 10−4 and hysteresis is 8.5%. Due to its simple fabrication process, the sensor has potential for application in environmental monitoring, where lower power consumption and small size are required. PMID:25192312

Econazole Nitrate Foam 1% Improves the Itch of Tinea Pedis.

PubMed

Fleischer, Alan B; Raymond, Isabelle

2016-09-01

Econazole nitrate topical foam, 1%, is indicated for the treatment of interdigital tinea pedis caused by Trichophyton rubrum, Trichophyton mentagrophytes, and Epidermophyton floccosum in patients 12 years of age and older. The symptom of itch or pruritus was evaluated in two randomized, double-blind, parallel-group, vehicle-controlled, multicenter Phase III studies in which econazole foam was compared with foam vehicle in subjects with interdigital tinea pedis. A thin, uniform layer of study treatment was applied once daily to all clinically affected interdigital regions of both feet for four weeks. At baseline, at least 69% of all subjects had moderate to severe itch. Throughout the duration of both studies, numerically econazole foam was numerically superior to vehicle in achieving absence of itch. After the cessation of treatment, from day 29, itching continues to improve until day 43 in the active treatment group, whereas there is no evident continued improvement within the vehicle foam groups. At day 43, in the active treatment groups, 83% in Study 1 and 71% in Study 2 achieved complete absence of itching. Using less stringent criteria, for the econazole nitrate foam arm, achieving no itch or mild itch (0 or 1), in Study 1, 95% and 86.8% in Study 2 achieved this outcome. Tolerability of the products was excellent with few treatment-related adverse events. In summary, econazole foam decreased the burden of itch as early as day 8 in patients with interdigital tinea pedis, and this improvement continued after cessation of treatment.

J Drugs Dermatol. 2016;15(9):1111-1114.

Direct versus indirect ACL femoral attachment fibres and their implications on ACL graft placement.

PubMed

Moulton, Samuel G; Steineman, Brett D; Haut Donahue, Tammy L; Fontboté, Cristián A; Cram, Tyler R; LaPrade, Robert F

2017-01-01

To further elucidate the direct and indirect fibre insertion morphology within the human ACL femoral attachment using scanning electron microscopy and determine where in the footprint each fibre type predominates. The hypothesis was that direct fibre attachment would be found centrally in the insertion site, while indirect fibre attachment would be found posteriorly adjacent to the posterior articular cartilage. Ten cadaveric knees were dissected to preserve and isolate the entirety of the femoral insertion of the ACL. Specimens were then prepared and evaluated with scanning electron microscopy to determine insertional fibre morphology and location. The entirety of the fan-like projection of the ACL attachment site lay posterior to the lateral intercondylar ridge. In all specimens, a four-phase architecture, consistent with previous descriptions of direct fibres, was found in the centre of the femoral attachment site. The posterior margin of the ACL attachment attached directly adjacent to the posterior articular cartilage with some fibres coursing into it. The posterior portion of the ACL insertion had a two-phase insertion, consistent with previous descriptions of indirect fibres. The transition from the ligament fibres to bone had less interdigitations, and the interdigitations were significantly smaller (p < 0.001) compared to the transition in the direct fibre area. The interdigitations of the direct fibres were 387 ± 81 μm (range 282-515 μm) wide, while the interdigitations of indirect fibres measured 228 ± 75 μm (range 89-331 μm). The centre of the ACL femoral attachment consisted of a direct fibre structure, while the posterior portion had an indirect fibre structure. These results support previous animal studies reporting that the centre of the ACL femoral insertion was comprised of the strongest reported fibre type. Clinically, the femoral ACL reconstruction tunnel should be oriented to cover the entirety of the central direct ACL fibres and may need to be customized based on graft type and the fixation device used during surgery.

Retinoic acid-independent expression of Meis2 during autopod patterning in the developing bat and mouse limb.

PubMed

Mason, Mandy K; Hockman, Dorit; Curry, Lyle; Cunningham, Thomas J; Duester, Gregg; Logan, Malcolm; Jacobs, David S; Illing, Nicola

2015-01-01

The bat has strikingly divergent forelimbs (long digits supporting wing membranes) and hindlimbs (short, typically free digits) due to the distinct requirements of both aerial and terrestrial locomotion. During embryonic development, the morphology of the bat forelimb deviates dramatically from the mouse and chick, offering an alternative paradigm for identifying genes that play an important role in limb patterning. Using transcriptome analysis of developing Natal long-fingered bat (Miniopterus natalensis) fore- and hindlimbs, we demonstrate that the transcription factor Meis2 has a significantly higher expression in bat forelimb autopods compared to hindlimbs. Validation by reverse transcriptase and quantitative polymerase chain reaction (RT-qPCR) and whole mount in situ hybridisation shows that Meis2, conventionally known as a marker of the early proximal limb bud, is upregulated in the bat forelimb autopod from CS16. Meis2 expression is localised to the expanding interdigital webbing and the membranes linking the wing to the hindlimb and tail. In mice, Meis2 is also expressed in the interdigital region prior to tissue regression. This interdigital Meis2 expression is not activated by retinoic acid (RA) signalling as it is present in the retained interdigital tissue of Rdh10 (trex/trex) mice, which lack RA. Additionally, genes encoding RA-synthesising enzymes, Rdh10 and Aldh1a2, and the RA nuclear receptor Rarβ are robustly expressed in bat fore- and hindlimb interdigital tissues indicating that the mechanism that retains interdigital tissue in bats also occurs independently of RA signalling. Mammalian interdigital Meis2 expression, and upregulation in the interdigital webbing of bat wings, suggests an important role for Meis2 in autopod development. Interdigital Meis2 expression is RA-independent, and retention of interdigital webbing in bat wings is not due to the suppression of RA-induced cell death. Rather, RA signalling may play a role in the thinning (rather than complete loss) of the interdigital tissue in the bat forelimb, while Meis2 may interact with other factors during both bat and mouse autopod development to maintain a pool of interdigital cells that contribute to digit patterning and growth.

High frequency GaAlAs modulator and photodetector for phased array antenna applications

NASA Technical Reports Server (NTRS)

Claspy, P. C.; Chorey, C. M.; Hill, S. M.; Bhasin, K. B.

1988-01-01

A waveguide Mach-Zehnder electro-optic modulator and an interdigitated photoconductive detector designed to operate at 820 nm, fabricated on different GaAlAs/GaAs heterostructure materials, are being investigated for use in optical interconnects in phased array antenna systems. Measured optical attenuation effects in the modulator are discussed and the observed modulation performance up to 1 GHz is presented. Measurements of detector frequency response are described and results presented.

Effects of Stretching Speed on Mechanical Rupture of Phospholipid/Cholesterol Bilayers: Molecular Dynamics Simulation

PubMed Central

Shigematsu, Taiki; Koshiyama, Kenichiro; Wada, Shigeo

2015-01-01

Rupture of biological cell membrane under mechanical stresses is critical for cell viability. It is triggered by local rearrangements of membrane molecules. We investigated the effects of stretching speed on mechanical rupture of phospholipid/cholesterol bilayers using unsteady molecular dynamics simulations. We focused on pore formation, the trigger of rupture, in a 40 mol% cholesterol-including bilayer. The unsteady stretching was modeled by proportional and temporal scaling of atom positions at stretching speeds from 0.025 to 30 m/s. The effects of the stretching speed on the critical areal strain, where the pore forms, is composed of two regimes. At low speeds (<1.0 m/s), the critical areal strain is insensitive to speed, whereas it significantly increases at higher speeds. Also, the strain is larger than that of a pure bilayer, regardless of the stretching speeds, which qualitatively agrees with available experimental data. Transient recovery of the cholesterol and phospholipid molecular orientations was evident at lower speeds, suggesting the formation of a stretch-induced interdigitated gel-like phase. However, this recovery was not confirmed at higher speeds or for the pure bilayer. The different responses of the molecular orientations may help explain the two regimes for the effect of stretching speed on pore formation. PMID:26471872

Effect of Parainfluenza-3 Neuraminidase on Bovine Nasal Secretion

PubMed Central

Morein, Bror; Bergman, Rune

1972-01-01

Three samples of bovine nasal secretion were each separated into a sol phase and a surface gel phase. In all samples, the gel phase contained an approximately four times greater amount of bound N-acetylneuraminic acid (NANA) than the sol phase. From the gel phase, bound NANA could be released by exposure to parainfluenza-3 virus neuraminidase. The surface gel appears to be a natural substrate for this enzyme. PMID:4347547

Density Functional Study of Stacking Structures and Electronic Behaviors of AnE-PV Copolymer.

PubMed

Dong, Chuan-Ding; Beenken, Wichard J D

2016-10-10

In this work, we report an in-depth investigation on the π-stacking and interdigitating structures of poly(p-anthracene-ethynylene)-alt-poly(p-phenylene-vinylene) copolymer with octyl and ethyl-hexyl side chains and the resulting electronic band structures using density functional theory calculations. We found that in the π-stacking direction, the preferred stacking structure, determined by the steric effect of the branched ethyl-hexyl side chains, is featured by the anthracene-ethynylene units stacking on the phenylene-vinylene units of the neighboring chains and vice versa. This stacking structure, combined with the interdigitating structure where the branched side chains of the laterally neighboring chains are isolated, defines the energetically favorable structure of the ordered copolymer phase, which provides a good compromise between light absorption and charge-carrier transport.

Dishwasher For Earth Or Outer Space

NASA Technical Reports Server (NTRS)

Tromble, Jon D.

1991-01-01

Dishwashing machine cleans eating utensils in either Earth gravity or zero gravity of outer space. Cycle consists of three phases: filling, washing, and draining. Rotation of tub creates artificial gravity aiding recirculation of water during washing phase in absence of true gravity. Centrifugal air/water separator helps system function in zero gravity. Self-cleaning filter contains interdigitating blades catching solid debris when water flows between them. Later, blades moved back and forth in scissor-like manner to dislodge debris, removed by backflow of water.

Interdigitation Zone Band Restoration After Treatment of Diabetic Macular Edema.

PubMed

Serizawa, Satoshi; Ohkoshi, Kishiko; Minowa, Yuko; Soejima, Kumiko

2016-09-01

To investigate whether the integrity of the interdigitation zone band, the ellipsoid zone band, and the external limiting membrane are reliable markers of treatment outcome in diabetic macular edema (DME). In this retrospective study, we examined 41 treatment-naïve eyes (38 patients) with DME that were treated with laser therapy, pharmacotherapy, and/or vitrectomy. Best-corrected visual acuity and the integrity of the interdigitation zone band, the ellipsoid zone band, and the external limiting membrane were assessed before treatment and at 3, 6, and 12 months after DME treatment. One year after treatment, the external limiting membrane, ellipsoid zone band, and interdigitation zone band were completely visible in 30 (73.2%), 24 (58.5%), and 2 (4.9%) eyes, respectively. Interdigitation zone band status improved significantly (P = 0.005) 1 year after treatment. The interdigitation zone did not improve in the absence of the ellipsoid zone band. Likewise, ellipsoid zone status did not improve in the absence of the external limiting membrane at any time after treatment. The results of this study show that restoration of the interdigitation zone band constitutes a very sensitive marker of DME treatment outcome when the ellipsoid zone band is visible before treatment.

Design and Fabrication of Interdigital Nanocapacitors Coated with HfO2

PubMed Central

González, Gabriel; Kolosovas-Machuca, Eleazar Samuel; López-Luna, Edgar; Hernández-Arriaga, Heber; González, Francisco Javier

2015-01-01

In this article nickel interdigital capacitors were fabricated on top of silicon substrates. The capacitance of the interdigital capacitor was optimized by coating the electrodes with a 60 nm layer of HfO2. An analytical solution of the capacitance was compared to electromagnetic simulations using COMSOL and with experimental measurements. Results show that modeling interdigital capacitors using Finite Element Method software such as COMSOL is effective in the design and electrical characterization of these transducers. PMID:25602271

Materials science of the gel to fluid phase transition in a supported phospholipid bilayer.

PubMed

Xie, Anne Feng; Yamada, Ryo; Gewirth, Andrew A; Granick, Steve

2002-12-09

We report the results of in situ AFM measurements examining the phase transition of bilayers formed from the zwitterionic phospholipid, DMPC, 1,2-dimyristoyl-sn-glycero-3-phosphocholine, supported on mica. The images show that the fluid to gel phase transition process features substantial tearing of the bilayer due to the density change between the two phases. The gel to fluid transition is strongly affected by the resultant stress introduced into the gel phase, which changes the degree of cooperativity, the shape of developing fluid phase regions, and the course of the transition.

Design of interdigital spiral and concentric capacitive sensors for materials evaluation

NASA Astrophysics Data System (ADS)

Chen, Tianming; Bowler, Nicola

2013-01-01

This paper describes the design of two circular coplanar interdigital sensors with i) a spiral interdigital configuration and ii) a concentric interdigital configuration for the nondestructive evaluation of multilayered dielectric structures. A numerical model accounting for sensor geometry, test-piece geometry and real permittivity, and metal electrode thickness has been developed to calculate the capacitance of the sensors when in contact with a planar test-piece comprising up to four layers. Compared with a disk-and-ring coplanar capacitive sensor developed previously, the interdigital configurations are predicted to have higher signal-to-noise ratio and better accuracy in materials characterization. The disk-and-ring configuration, on the other hand, possesses advantages such as deeper penetration depth and better immunity to lift-off variations.

Compact injector with alternating phase focusing-interdigital H-mode linac and superconducting electron cyclotron resonance ion source for heavy ion cancer therapy

NASA Astrophysics Data System (ADS)

Hayashizaki, Noriyosu; Hattori, Toshiyuki; Matsui, Shinjiro; Tomizawa, Hiromitsu; Yoshida, Toru; Isokawa, Katsushi; Kitagawa, Atsushi; Muramatsu, Masayuki; Yamada, Satoru; Okamura, Masahiro

2000-02-01

We have researched a compact medical accelerator with low investment and running cost for the popularization of heavy ion cancer therapy. As the first step, the compact injector system has been investigated for a Heavy Ion Medical Accelerator in Chiba at National Institute of Radiological Sciences. The proposed new injector system consists of a 6 MeV/u interdigital H-mode (IH) linac of 3.1 m long and a 18 GHz superconducting electron cyclotron resonance (ECR) (SC-ECR) ion source. The IH linac with high power efficiency is appropriate to a medical and industrial injector system. Its beam trajectory was simulated and a prototype has been constructed. The SC-ECR ion source has been designed to realize lightweight and low power consumption and the mirror field distribution was estimated.

The incidence of tinea pedis in diabetic versus nondiabetic patients with interdigital macerations: a prospective study.

PubMed

Legge, Bradford S; Grady, John F; Lacey, Autum M

2008-01-01

We sought to determine the incidence of tinea pedis in patients with otherwise asymptomatic pedal interdigital macerations. Both diabetic and nondiabetic populations were compared. Age and body mass index were also examined for their significance. Fungal cultures of skin scrapings from 80 patients (77 male and 3 female; mean age, 65 years) with interdigital macerations were performed; 40 patients had previously been diagnosed with type 2 diabetes and 40 did not have diabetes. Cultures revealed a 40% prevalence of tinea pedis in the total study population. The prevalence in the nondiabetic group was 37.5% and 42.5% for the diabetic group. This was not a statistically significant difference. Among patients with interdigital macerations that yielded positive fungal cultures, those in the nondiabetic group were 6.3 years older than those in the diabetic group. It was also observed that the nondiabetic patients with interdigital macerations yielding positive fungal cultures were 9.1 years older than patients with negative fungal cultures in the nondiabetic group. The results of this study provide the practitioner with a guide for treating pedal interdigital macerations. Because the likelihood of a tinea pedis infection is 40%, it seems prudent to treat these macerations with an antifungal agent. In regard to age, the results suggest that as nondiabetic patients age, the likelihood of an otherwise asymptomatic interdigital maceration yielding a positive fungal culture increases, and that diabetic patients may be susceptible to interdigital fungal infections at a younger age than those without diabetes.

Control of gel swelling and phase separation of weakly charged thermoreversible gels by salt addition

PubMed Central

Solis, Francisco J.; Vernon, Brent

2009-01-01

Doping of thermoreversible polymer gels with charged monomers provides a way to control phase separation and gelation conditions by coupling the properties of the gel with a tunable ionic environment. We analyze the dependence of the gelation and phase separation conditions on the amount of salt present using a mean field model of weakly charged associative polymers. The ions and co-ions present are explicitly considered at the mean field level, and we determine their concentrations in the different equilibrium phases when the system undergoes phase separation. For weak polymer charge, the entropic contributions of the ions to the free energy of the system play a central role in the determination of the location of phase equilibrium. In the simplest case, when the associative interaction responsible for gel formation is independent of the electrostatic interaction, the addition of salt changes the polymer equilibrium concentrations and indirectly changes the measurable swelling of the gel. We construct phase diagrams of these systems showing the location of the coexistence region, the gel-sol boundary and the location of the tie-lines. We determine the swelling of the gel within the co-existence region. Our main result is that the description of the effect of the salt on the properties of the weakly charged gel can be described through an extra contribution to the effective immiscibility parameter χ proportional to the square of the doping degree f2 and to the inverse square of the added salt concentration s−2. PMID:19759854

Interdigital erosions - tinea pedis?

PubMed

Orgaz-Molina, Jacinto; Orgaz-Molina, Maria Carmen; Cutugno, Marilena; Arias-Santiago, Salvador

2012-10-01

Interdigital erosions are frequently due to tinea pedis. However, other infectious conditions, such as candidiasis, erythrasma or bacterial infections, can generate lesions that cannot be differentiated at the clinical level. Microbiological tests are therefore necessary. This clinical case shows a man with interdigital lesions of 10 months of evolution that are not responding to antifungal treatment.

Tinea pedis acquired in mosques?

PubMed

Veraldi, Stefano; Esposito, Luigi; Gorani, Alberto

2018-03-30

Interdigital tinea pedis is a mycotic infection of the feet which occurs mainly in adult males. The transmission is due to repeated contacts with the soil. In Italy, Trichophyton rubrum, T. mentagrophytes (including T. mentagrophytes var. interdigitale) and Epidermophyton floccosum are the most frequently involved species. Interdigital tinea pedis is characterized clinically by maceration, erythema, vesicles, scales, crusts, erosions and ulcers located at the 2 nd , 3 rd and 4 th interdigital folds. Interdigital tinea pedis may be asymptomatic; however, when erosions and ulcers occur, the patients may complain of pruritus, burning sensation and pain. Superinfections, caused by Candida albicans and Gram-negative bacteria, are not rare. 1 We present four cases of interdigital tinea pedis which was probably acquired in Turkish mosques and holy Muslim places. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Optical-Microwave Interactions in Semiconductor Devices.

DTIC Science & Technology

1981-03-01

Interdigital Photoconductors ( IDPC ) ......... ..... 112 G. Conclusions.. ....... .. 120 6 CONCLUSIONS AND RECOMMENDATIONS FOR FUTURE WORK . 121...The detector developed at the Hughes Research Laboratories ( IDPC ) involves placing an interdigital metal electrode 53- 5 5 structure on top of a F...easier to perform with the IDPC detector. We believe the interdigital photoconductive detector has many advantages over existing detectors. First, the

Fabrication of interdigitated high-performance zinc oxide nanowire modified electrodes for glucose sensing.

PubMed

Haarindraprasad, R; Hashim, Uda; Gopinath, Subash C B; Perumal, Veeradasan; Liu, Wei-Wen; Balakrishnan, S R

2016-06-21

Diabetes is a metabolic disease with a prolonged elevated level of glucose in the blood leads to long-term complications and increases the chances for cardiovascular diseases. The present study describes the fabrication of a ZnO nanowire (NW)-modified interdigitated electrode (IDE) to monitor the level of blood glucose. A silver IDE was generated by wet etching-assisted conventional lithography, with a gap between adjacent electrodes of 98.80 μm. The ZnO-based thin films and NWs were amended by sol-gel and hydrothermal routes. High-quality crystalline and c-axis orientated ZnO thin films were observed by XRD analyses. The ZnO thin film was annealed for 1, 3 and 5 h, yielding a good-quality crystallite with sizes of 50, 100 and 110 nm, and the band gaps were measured as 3.26, 3.20 and 3.17 eV, respectively. Furthermore, a flower-modeled NW was obtained with the lowest diameter of 21 nm. Our designed ZnO NW-modified IDE was shown to have a detection limit as low as 0.03 mg/dL (correlation coefficient = 0.98952) of glucose with a low response time of 3 s, perform better than commercial glucose meter, suitable to instantly monitor the glucose level of diabetes patients. This study demonstrated the high performance of NW-mediated IDEs for glucose sensing as alternative to current glucose sensors. Copyright © 2016 Elsevier B.V. All rights reserved.

Lipid Bilayers in the Gel Phase Become Saturated by Triton X-100 at Lower Surfactant Concentrations Than Those in the Fluid Phase

PubMed Central

Ahyayauch, Hasna; Collado, M. Isabel; Alonso, Alicia; Goñi, Felix M.

2012-01-01

It has been repeatedly observed that lipid bilayers in the gel phase are solubilized by lower concentrations of Triton X-100, at least within certain temperature ranges, or other nonionic detergents than bilayers in the fluid phase. In a previous study, we showed that detergent partition coefficients into the lipid bilayer were the same for the gel and the fluid phases. In this contribution, turbidity, calorimetry, and 31P-NMR concur in showing that bilayers in the gel state (at least down to 13–20°C below the gel-fluid transition temperature) become saturated with detergent at lower detergent concentrations than those in the fluid state, irrespective of temperature. The different saturation may explain the observed differences in solubilization. PMID:22713566

Phase behavior of gemini surfactant hexylene-1,6-bis(dodecyldimethylammonium bromide) and polyelectrolyte NaPAA.

PubMed

Pi, Yingying; Shang, Yazhuo; Peng, Changjun; Liu, Honglai; Hu, Ying; Jiang, Jianwen

2006-07-01

The phase behavior of aqueous mixtures of gemini surfactant hexylene-1,6-bis(dodecyldimethylammonium bromide) (12-6-12) and oppositely charged polyelectrolyte sodium polyacrylate (NaPAA) has been studied experimentally. Compared to the mixtures of the traditional surfactant dodecyltrimethylammonium bromide (DTAB) and NaPAA, the gel phase region in the 12-6-12/NaPAA solution is larger. Element analysis reveals that NaPAA in the gel phase tends to replace the counterions of surfactant micelle and to release its own counterions. Spherical aggregates are observed in either top or bottom gel phase as detected by transmission electron microscopy. The addition of sodium bromide (NaBr) leads to a decrease in the gel phase region and the occurrence of a new cream phase.

All optical controlled photonic integrated circuits using azo dye functionized sol-gel material

NASA Astrophysics Data System (ADS)

Ke, Xianjun

The main focus of this dissertation is development and characterization of all-optical controllable azo dye functionized sol gel material, demonstrating a PIC fabrication technique on glass substrate using such material, and exploration and feasibility demonstration of three PIC functional devices namely optical variable attenuator, optical switches, and optical tunable filters using the material. The realization of all the devices in this dissertation are based on one material: dye functionalized sol-gel material. A photochromic sol-gel material functionalized with azo dye was synthesized and characterized. It possesses a photochromic characteristic under the control of green laser beam illumination. The material characteristics suggest the possibility of a new promising material platform candidate for the fabrication of alloptical controlled photonic integrated circuits. As the first potential application of the dye functionalized sol-gel material, an alloptical variable attenuator was designed and demonstrated. The optical variable attenuation is achieved in Mach-Zehnder interferometric configuration through all-optical modulation of sol-gel waveguide phase shifters. A 2 x 2 optical switch based on multimode interference (MMI) waveguide structure is proposed in the dissertation. The schematic configuration of the optical switch consists of a cascade of two identical MMIs with two all-optical controlled phase shifters realized by using the photochromic sol-gel material. The cross or bar switch state of the optical switch is determined by the phase difference between the two sol-gel waveguide phase shifters. An all-optical tunable filter is designed and its feasibility demonstrated by using the sol-gel photochromic material. Except for the phase change demonstrated on sol-gel waveguide phase shifters, dynamic gratings were observed on sol-gel film when exposed to two interference beams. This reveals the possibility of realizing Bragg grating-based tunable filters. The schematic configuration of proposed tunable filters consists of a single straight waveguide embedded with a sol-gel waveguide. The wavelength tuning of the tunable filters is accomplished by varying the grating period.

Efficacy and safety of once-daily luliconazole 1% cream in patients ≥12 years of age with interdigital tinea pedis: a phase 3, randomized, double-blind,vehicle-controlled study.

PubMed

Jarratt, Michael; Jones, Terry; Adelglass, Jeffrey; Bucko, Alicia; Pollak, Richard; Roman-Miranda, Amaury; Olin, Jason T; Swinyer, Leonard

2014-07-01

Interdigital tinea pedis is one of the most common clinical presentations of dermatophytosis. This phase 3 study evaluated the safety and efficacy of luliconazole cream 1% in patients with tinea pedis. A total of 321 male and female patients aged ≥12 years with tinea pedis and eligible for modified intent-to-treat analysis were randomized 1:1 to receive luliconazole cream 1% (n=159) or vehicle (n=162) once daily for 14 days. Efficacy was evaluated at days 28 and 42 (i.e., days 14 and 28 posttreatment) based on clinical signs (erythema, scaling, pruritus) and mycology (KOH, fungal culture). The primary outcome was complete clearance at day 42. Safety evaluations included adverse events and laboratory assessments. Complete clearance at day 42 was achieved in 26.4% (28/106) of patients treated with luliconazole cream 1% compared with 1.9% (2/103) of patients treated with vehicle (P< 0.001). Similar safety profiles were obtained for luliconazole cream 1% and vehicle. This study was conducted in a relatively small population under controlled clinical trial conditions. Luliconazole cream 1% applied once daily for 14 days is well tolerated and more effective than vehicle in patients with tinea pedis.

Self assembly of organic nanostructures and dielectrophoretic assembly of inorganic nanowires.

NASA Astrophysics Data System (ADS)

Dholakia, Geetha; Kuo, Steven; Allen, E. L.

2007-03-01

Self assembly techniques enable the organization of organic molecules into nanostructures. Currently engineering strategies for efficient assembly and routine integration of inorganic nanoscale objects into functional devices is very limited. AC Dielectrophoresis is an efficient technique to manipulate inorganic nanomaterials into higher dimensional structures. We used an alumina template based sol-gel synthesis method for the growth of various metal oxide nanowires with typical diameters of 100-150 nm, ranging in length from 3-10 μm. Here we report the dielectrophoretic assembly of TiO2 nanowires, an important material for photocatalysis and photovoltaics, onto interdigitated devices. Self assembly in organic nanostructures and its dependence on structure and stereochemistry of the molecule and dielectrophoretic field dependence in the assembly of inorganic nanowires will be compared and contrasted. Tunneling spectroscopy and DOS of these nanoscale systems will also be discussed.

Coencapsulation of (-)-Epigallocatechin-3-gallate and Quercetin in Particle-Stabilized W/O/W Emulsion Gels: Controlled Release and Bioaccessibility.

PubMed

Chen, Xing; McClements, David Julian; Wang, Jian; Zou, Liqiang; Deng, Sumeng; Liu, Wei; Yan, Chi; Zhu, Yuqing; Cheng, Ce; Liu, Chengmei

2018-04-11

Particle-stabilized W 1 /O/W 2 emulsion gels were fabricated using a two-step procedure: ( i) a W 1 /O emulsion was formed containing saccharose (for osmotic stress balance) and gelatin (as a gelling agent) in the aqueous phase and polyglycerol polyricinoleate (a lipophilic surfactant) in the oil phase; ( ii) this W 1 /O emulsion was then homogenized with another water phase (W 2 ) containing wheat gliadin nanoparticles (hydrophilic emulsifier). The gliadin nanoparticles in the external aqueous phase aggregated at pH 5.5, which led to the formation of particle-stabilized W 1 /O/W 2 emulsion gels with good stability to phase separation. These emulsion gels were then used to coencapsulate a hydrophilic bioactive (epigallocatechin-3-gallate, EGCG) in the internal aqueous phase (encapsulation efficiency = 65.5%) and a hydrophobic bioactive (quercetin) in the oil phase (encapsulation efficiency = 97.2%). The emulsion gels improved EGCG chemical stability and quercetin solubility under simulated gastrointestinal conditions, which led to a 2- and 4-fold increase in their effective bioaccessibility, respectively.

Simulations and design of microfabricated interdigitated electrodes for use in a gold nanoparticle enhanced biosensor.

PubMed

Hermansen, Peter; MacKay, Scott; Wishart, David; Jie Chen

2016-08-01

Microfabricated interdigitated electrode chips have been designed for use in a unique gold-nanoparticle based biosensor system. The use of these electrodes will allow for simple, accurate, inexpensive, and portable biosensing, with potential applications in diagnostics, medical research, and environmental testing. To determine the optimal design for these electrodes, finite element analysis simulations were carried out using COMSOL Multiphysics software. The results of these simulations determined some of the optimal design parameters for microfabricating interdigitated electrodes as well as predicting the effects of different electrode materials. Finally, based on the results of these simulations two different kinds of interdigitated electrode chips were made using photolithography.

Field alignment of bent-core smectic liquid crystals for analog optical phase modulation

NASA Astrophysics Data System (ADS)

Shen, Y.; Goodhew, L.; Shao, R.; Moran, M.; Korblova, E.; Walba, D. M.; Clark, N. A.; Maclennan, J. E.; Rudquist, P.

2015-05-01

A general method for aligning bent-core smectic liquid crystal materials is described. Alternating electric fields between interdigitated electrodes patterned on one cell surface create torques on the liquid crystal that result in uniform "bookshelf" orientation of the smectic layers. The aligned cell can then be driven in the conventional way by applying an electric field between all of the stripe electrodes connected together and a monolithic electrode on the other cell surface. Fast, analog, optical phase-only modulation is demonstrated in a device containing a polar, bent-core SmAPF material aligned using this technique.

Lamellar biogels comprising fluid membranes with a newly synthesized class of polyethylene glycol-surfactants

NASA Astrophysics Data System (ADS)

Warriner, Heidi E.; Davidson, Patrick; Slack, Nelle L.; Schellhorn, Matthias; Eiselt, Petra; Idziak, Stefan H. J.; Schmidt, Hans-Werner; Safinya, Cyrus R.

1997-09-01

A series of four polymer-surfactant macromolecules, each consisting of a double-chain hydrophobic moiety attached onto a monofunctional polyethylene glycol (PEG) polymer chain, were synthesized in order to study their effect upon the fluid lamellar liquid crystalline (Lα) phase of the dimyristoylphosphatidylcholine/pentanol/water system. The main finding of this study is that the addition of these compounds induces a new lamellar gel, called Lα,g. We have determined the phase diagrams as a function of PEG-surfactant concentration, cPEG, and weight fraction water, ΦW. All phase diagrams are qualitatively similar and show the existence of the gel. Unlike more common polymer physical gels, this gel can be induced either by increasing cPEG or by adding water at constant cPEG. In particular, less polymer is required for gelation as water concentration increases. Moreover, the gel phase is attained at concentrations of PEG-surfactant far below that required for classical polymer gels and is stable at temperatures comparable to the lower critical solution temperature of free PEG-water mixtures. Small angle x-ray experiments demonstrate the lamellar structure of the gel phase, while wide angle x-ray scattering experiments prove that the structure is Lα, not Lβ' (a common chain-ordered phase which is also a gel). The rheological behavior of the Lα,g phase demonstrates the existence of three dimensional elastic properties. Polarized light microscopy of Lα,g samples reveals that the Lα,g is induced by a proliferation of defect structures, including whispy lines, spherulitic defects, and a nematiclike Schlieren texture. We propose a model of topological defects created by the aggregation of PEG-surfactant into highly curved regions within the membranes. This model accounts for both the inverse relationship between ΦW and cPEG observed along the gel transition line and the scaling dependence of the interlayer spacing at the gel transition with the PEG molecular weight. These Lα hydrogels could serve as the matrix for membrane-anchored peptides, proteins or other drug molecules, creating a "bioactive gel" with mechanical stability deriving from the polymer-lipid minority component.

An interdigit signalling centre instructs coordinate phalanx-joint formation governed by 5′Hoxd–Gli3 antagonism

PubMed Central

Huang, Bau-Lin; Trofka, Anna; Furusawa, Aki; Norrie, Jacqueline L.; Rabinowitz, Adam H.; Vokes, Steven A.; Mark Taketo, M.; Zakany, Jozsef; Mackem, Susan

2016-01-01

The number of phalanges and joints are key features of digit ‘identity' and are central to limb functionality and evolutionary adaptation. Prior chick work indicated that digit phalanges and their associated joints arise in a different manner than the more sparsely jointed long bones, and their identity is regulated by differential signalling from adjacent interdigits. Currently, there is no genetic evidence for this model, and the molecular mechanisms governing digit joint specification remain poorly understood. Using genetic approaches in mouse, here we show that functional 5′Hoxd–Gli3 antagonism acts indirectly, through Bmp signalling from the interdigital mesenchyme, to regulate specification of joint progenitors, which arise in conjunction with phalangeal precursors at the digit tip. Phalanx number, although co-regulated, can be uncoupled from joint specification. We propose that 5′Hoxd genes and Gli3 are part of an interdigital signalling centre that sets net Bmp signalling levels from different interdigits to coordinately regulate phalanx and joint formation. PMID:27713395

Thermal properties of the gel made by low molecular weight gelator 1,2-O-(1-ethylpropylidene)-alpha-D-glucofuranose with toluene and molecular dynamics of solvent.

PubMed

Tritt-Goc, Jadwiga; Bielejewski, Michał; Luboradzki, Roman; Lapiński, Andrzej

2008-01-15

The studies of the gel-to-sol phase transition by the Raman, FT-IR, and 1H NMR methods of the gel made by low molecular weight organogelator 1,2-O-(1-ethylpropylidene)-alpha-D-glucofuranose with toluene as the solvent are reported. The FT-IR spectra revealed the existence of a hydrogen bond network formed by gelator molecules in the crystalline and gel phase. In both phases, the network formation is dominated by the gelator self-interaction. Upon gelation, only one stretching band of infrared absorption modes nualpha, assigned to the O(6)H hydroxyl protons of gelator, is shifted by Deltaupsilonalpha = 25 cm-1, which indicates the involvement of this proton in the interaction with the solvent molecules. The phase transition measurements performed as a function of gelator concentration allowed the calculation of the energy correlated with the transition from gel to solution phase. The obtained value of 72 kJ/mol is the largest one reported up until now for monosaccharide-based gels. The analysis of the temperature measurements of the toluene 1H NMR spectra provides evidence for a different chemical environment of toluene molecules in the gel. The toluene spin-lattice relaxation in bulk and gel indicate that the viscosity is most likely the main factor that influences the dynamics of toluene.

Tamoxifen-model membrane interactions: an FT-IR study

NASA Astrophysics Data System (ADS)

Boyar, Handan; Severcan, Feride

1997-06-01

The temperature- and concentration-induced effects of tamoxifen (TAM) on dipalmitoyl phosphatidylcholine (DPPC) model membranes were investigated by the Fourier transform-infrared (FT-IR) spectroscopic technique. An investigation of the C-H stretching region and the CO mode reveals that the inclusion of TAM changes the physical properties of the DPPC multibilayers by (i) shifting the main phase transition to lower temperatures; (ii) broadening the transition profile slightly; (iii) disordering the system in the gel and in the liquid crystalline phases; (iv) increasing the dynamics in the gel phase and decreasing the dynamics of the acyl chains in the liquid crystalline phase; (v) increasing the mobility of the terminal methyl group region of the bilayer in the gel phase and decreasing it in the liquid crystalline phase; (vi) increasing the frequency of the CO stretching mode both in the gel and in the liquid crystalline phases, i.e. non-bonding with carbonyl groups.

Morphological diversity of the avian foot is related with the pattern of msx gene expression in the developing autopod.

PubMed

Gañan, Y; Macias, D; Basco, R D; Merino, R; Hurle, J M

1998-04-01

The formation of the digits in amniota embryos is accompanied by apoptotic cell death of the interdigital mesoderm triggered through BMP signaling. Differences in the intensity of this apoptotic process account for the establishment of the different morphological types of feet observed in amniota (i.e., free-digits, webbed digits, lobulated digits). The molecular basis accounting for the differential pattern of interdigital cell death remains uncertain since the reduction of cell death in species with webbed digits is not accompanied by a parallel reduction in the pattern of expression of bmp genes in the interdigital regions. In this study we show that the duck interdigital web mesoderm exhibits an attenuated response to both BMP-induced apoptosis and TGFbeta-induced chondrogenesis in comparison with species with free digits. The attenuated response to these signals is accompanied by a reduced pattern of expression of msx-1 and msx-2 genes. Local application of FGF in the duck interdigit expands the domain of msx-2 expression but not the domain of msx-1 expression. This change in the expression of msx-2 is followed by a parallel increase in spontaneous and exogenous BMP-induced interdigital cell death, while the chondrogenic response to TGFbetas is unchanged. The regression of AER, as deduced by the pattern of extinction of fgf-8 expression, takes place in a similar fashion in the chick and duck regardless of the differences in interdigital cell death and msx gene expression. Implantation of BMP-beads in the distal limb mesoderm induces AER regression in both the chick and duck. This finding suggests an additional role for BMPs in the physiological regression of the AER. It is proposed that the formation of webbed vs free-digit feet in amniota results from a premature differentiation of the interdigital mesoderm into connective tissue caused by a reduced expression of msx genes in the developing autopod. Copyright 1998 Academic Press.

Investigation of phase evolution of CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) by in situ synchrotron high-temperature powder diffraction

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

Ouyang, Xin; Huang, Saifang; School of Materials Science and Technology, China University of Geosciences

2014-03-15

In situ synchrotron X-ray powder diffraction was used to study the high-temperature phase evolution of CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) precursors prepared via solid-state and sol–gel methods. After the precursors are heated to 1225 °C, the CCTO phase is the main phase observed in the calcined powder, with the presence of some minor impurities. Comparing the two precursors, we found that the onset temperature for the CCTO phase formation is 800 °C in the sol–gel precursor, lower than that in the solid-state precursor (875 °C). Intermediate phases were only observed in the sol–gel precursor. Both precursors are able to bemore » calcined to sub-micrometric sized powders. Based on the synchrotron data along with differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA), the phase formation sequence and mechanism during calcination are proposed in this study. -- Graphical abstract: The in situ synchrotron HT-XRD patterns of CCTO sol–gel and solid-state precursor. Highlights: • Phase formation sequence/mechanism in two CCTO precursors has been established. • Formation temperature of CCTO via sol–gel method is lower than solid-state method. • Intermediate phases are only observed in the sol–gel precursor. • Both precursors are able to be calcined into sub-micrometric sized powders.« less

The phototoxic and photoallergy potential of clindamycin phosphate 1.2%/ tretinoin 0.025% gel for facial acne: results of two single-center, evaluator-blinded, randomized, vehicle-controlled phase 1 studies in healthy volunteers.

PubMed

Murray, John; Potts, Aaron

2014-01-01

A fixed-dose combination of clindamycin phosphate 1.2% and tretinoin 0.025% gel (VELTIN® (clindamycin phosphate and tretinoin) 1.2%/0.025% Gel [VELTIN]) (clindamycin/tretinoin gel) is currently available for the once-daily topical treatment of acne. Two-phase I studies were conducted to evaluate the phototoxic and photoallergic potential of clindamycin/tretinoin gel. Study 1 (phototoxic) (n=37) and Study 2 (photoallergic) (n=58) were single-center, evaluator-blinded, randomized, vehicle-controlled, phase 1 studies conducted in healthy volunteers. In Study 1, clindamycin/tretinoin gel patches, vehicle gel patches and blank patches (no gel) were applied concurrently for 24 hours to naïve sites. After patch removal, sites were irradiated with 16 joules/cm2 of ultraviolet A light (UVA) then 0.75 minimal erythema dose (MED) of UVA/ultraviolet B light (UVB), the same irradiation protocol followed by 15 joules/cm2 of visible light (VIS), or served as non-irradiated controls. Study 2 examined the effect of repeated drug exposure and involved an induction period (6 repeat phases at the same body sites during which clindamycin/tretinoin gel and vehicle gel patches were applied for 24 hours, removed and sites irradiated with UVB +/- VIS), followed by a rest period (10 to 17 days), then a challenge period that used the protocol described for Study 1. In both studies, inflammatory responses and other cutaneous effects were evaluated at 1, 24, 48, and 72 hours after patch removal. No subject experienced any adverse events in Study 1 (phototoxic). One subject in Study 2 (photoallergic) experienced AEs (diffuse erythema; mild application site irritation at one each of UV/VIS-irradiated clindamycin/tretinoin gel and vehicle gel patch sites) considered definitely related to study product that resulted in discontinuation from the study. Data from Study 1 and the challenge phase from Study 2 showed most subjects had no visible inflammatory reaction to clindamycin/tretinoin gel after irradiation. Clindamycin/tretinoin gel has a favorable safety profile following UV/visible irradiation and a low potential for phototoxicity and photoallergenicity.

Performance tradeoff between lateral and interdigitated doping patterns for high speed carrier-depletion based silicon modulators.

PubMed

Yu, Hui; Pantouvaki, Marianna; Van Campenhout, Joris; Korn, Dietmar; Komorowska, Katarzyna; Dumon, Pieter; Li, Yanlu; Verheyen, Peter; Absil, Philippe; Alloatti, Luca; Hillerkuss, David; Leuthold, Juerg; Baets, Roel; Bogaerts, Wim

2012-06-04

Carrier-depletion based silicon modulators with lateral and interdigitated PN junctions are compared systematically on the same fabrication platform. The interdigitated diode is shown to outperform the lateral diode in achieving a low VπLπ of 0.62 V∙cm with comparable propagation loss at the expense of a higher depletion capacitance. The low VπLπ of the interdigitated PN junction is employed to demonstrate 10 Gbit/s modulation with 7.5 dB extinction ration from a 500 µm long device whose static insertion loss is 2.8 dB. In addition, up to 40 Gbit/s modulation is demonstrated for a 3 mm long device comprising a lateral diode and a co-designed traveling wave electrode.

Interdigitated electrodes as impedance and capacitance biosensors: A review

NASA Astrophysics Data System (ADS)

Mazlan, N. S.; Ramli, M. M.; Abdullah, M. M. A. B.; Halin, D. S. C.; Isa, S. S. M.; Talip, L. F. A.; Danial, N. S.; Murad, S. A. Z.

2017-09-01

Interdigitated electrodes (IDEs) are made of two individually addressable interdigitated comb-like electrode structures. IDEs are one of the most favored transducers, widely utilized in technological applications especially in the field of biological and chemical sensors due to their inexpensive, ease of fabrication process and high sensitivity. In order to detect and analyze a biochemical molecule or analyte, the impedance and capacitance signal need to be obtained. This paper investigates the working principle and influencer of the impedance and capacitance biosensors. The impedance biosensor depends on the resistance and capacitance while the capacitance biosensor influenced by the dielectric permittivity. However, the geometry and structures of the interdigitated electrodes affect both impedance and capacitance biosensor. The details have been discussed in this paper.

A multicenter study of topical azelaic acid 15% gel in combination with oral doxycycline as initial therapy and azelaic acid 15% gel as maintenance monotherapy.

PubMed

Thiboutot, Diane M; Fleischer, Alan B; Del Rosso, James Q; Rich, Phoebe

2009-07-01

This two-phase, multicenter study was undertaken to examine the safety and efficacy of combination therapy with oral doxycycline and topical azelaic acid (AzA) 15% gel in moderate-to-severe papulopustular rosacea and to determine the effect of subsequent maintenance monotherapy with AzA 15% gel alone. In the initial open-label, non-randomized phase of the study, subjects (n=172) received topical AzA 15% gel and oral doxycycline (100 mg), both twice daily, for < or = 12 weeks. In the second, double-blind study phase, subjects who had initially undergone at least four weeks of combination treatment in phase 1 and who achieved > or = 75% inflammatory lesion count reduction (n=136) were randomized to receive either AzA 15% gel or its vehicle twice daily for an additional 24 weeks. Assessments of efficacy were obtained at four-week intervals throughout both phases of the study and included change in inflammatory lesion count, investigator global assessment (IGA) of rosacea severity, and separate assessments of erythema and telangiectasia severity. At the last visit for each phase of the study, the investigator and participant each rated overall improvement, with the participant rating cosmetic acceptability and the investigator rating treatment as "success" or "failure" based on IGA score. During the second phase of the trial, the rate of relapse -- defined as either a 50% deterioration in the lesion count improvement from phase 1, an increase in erythema intolerable to the subject or maintenance therapy failure as judged by the investigator and/or the subject -- was obtained. Safety assessments were conducted for both phases of the study and included analysis of adverse events (AEs) and a rating of cutaneous tolerability by the subject. By week 12 of the open-label phase of the study, 81.4% of subjects had reached a 75% or greater reduction in inflammatory lesion count, and 64% of patients achieved treatment success. During the second study phase (maintenance phase), AzA 15% gel consistently provided a better maintenance response than vehicle, with maintenance of remission in 75% of patients over the six-month duration of the maintenance phase. Additionally AzA 15% gel showed a statistically significantly lower deterioration in absolute inflammatory lesion counts than did vehicle after 8, 16, 20 and 24 weeks of maintenance therapy. No serious treatment-related AEs were encountered in the study, and 98.5% of subjects were satisfied with the local tolerability of both AzA gel and vehicle.

Gel phase in hydrated calcium dipicolinate

NASA Astrophysics Data System (ADS)

Rajak, Pankaj; Mishra, Ankit; Sheng, Chunyang; Tiwari, Subodh; Krishnamoorthy, Aravind; Kalia, Rajiv K.; Nakano, Aiichiro; Vashishta, Priya

2017-11-01

The mineralization of dipicolinic acid (DPA) molecules in bacterial spore cores with Ca2+ ions to form Ca-DPA is critical to the wet-heat resistance of spores. This resistance to "wet-heat" also depends on the physical properties of water and DPA in the hydrated Ca-DPA-rich protoplasm. Using reactive molecular dynamics simulations, we have determined the phase diagram of hydrated Ca-DPA as a function of temperature and water concentration, which shows the existence of a gel phase along with distinct solid-gel and gel-liquid phase transitions. Simulations reveal monotonically decreasing solid-gel-liquid transition temperatures with increasing hydration, which explains the experimental trend of wet-heat resistance of bacterial spores. Our observation of different phases of water also reconciles previous conflicting experimental findings on the state of water in bacterial spores. Further comparison with an unmineralized hydrated DPA system allows us to quantify the importance of Ca mineralization in decreasing diffusivity and increasing the heat resistance of the spore.

New ordered metastable phases between the gel and subgel phases in hydrated phospholipids.

PubMed Central

Tenchov, B; Koynova, R; Rapp, G

2001-01-01

Formation of low-temperature ordered gel phases in several fully hydrated phosphatidylethanolamines (PEs) and phosphatidylcholines (PCs) with saturated chains as well as in dipalmitoylphosphatidylglycerol (DPPG) was observed by synchrotron x-ray diffraction, microcalorimetry, and densitometry. The diffraction patterns recorded during slow cooling show that the gel-phase chain reflection cooperatively splits into two reflections, signaling a transformation of the usual gel phase into a more ordered phase, with an orthorhombic chain packing (the Y-transition). This transition is associated with a small decrease (2-4 microl/g) or inflection of the partial specific volume. It is fully reversible with the temperature and displays in heating direction as a small (0.1-0.7 kcal/mol) endothermic event. We recorded a Y-transition in distearoyl PE, dipalmitoyl PE (DPPE), mono and dimethylated DPPE, distearoyl PC, dipalmitoyl PC, diC(15)PC, and DPPG. No such transition exists in dimyristoyl PE and dilauroyl PE where the gel L(beta) phase transforms directly into subgel L(c) phase, as well as in the unsaturated dielaidoyl PE. The PE and PC low-temperature phases denoted L(R1) and SGII, respectively, have different hydrocarbon chain packing. The SGII phase is with tilted chains, arranged in an orthorhombic lattice of two-nearest-neighbor type. Except for the PCs, it was also registered in ionized DPPG. In the L(R1) phase, the chains are perpendicular to the bilayer plane and arranged in an orthorhombic lattice of four-nearest-neighbor type. It was observed in PEs and in protonated DPPG. The L(R1) and SGII phases are metastable phases, which may only be formed by cooling the respective gel L(beta) and L(beta') phases, and not by heating the subgel L(c) phase. Whenever present, they appear to represent an indispensable intermediate step in the formation of the latter phase. PMID:11259300

Gel phase formation in dilute triblock copolyelectrolyte complexes

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

Srivastava, Samanvaya; Andreev, Marat; Levi, Adam E.

Assembly of oppositely charged triblock copolyelectrolytes into phase-separated gels at low polymer concentrations (<1% by mass) has been observed in scattering experiments and molecular dynamics simulations. Here we show that in contrast to uncharged, amphiphilic block copolymers that form discrete micelles at low concentrations and enter a phase of strongly interacting micelles in a gradual manner with increasing concentration, the formation of a dilute phase of individual micelles is prevented in polyelectrolyte complexation-driven assembly of triblock copolyelectrolytes. Gel phases form and phase separate almost instantaneously on solvation of the copolymers. Furthermore, molecular models of self-assembly demonstrate the presence of oligo-chainmore » aggregates in early stages of copolyelectrolyte assembly, at experimentally unobservable polymer concentrations. Our discoveries contribute to the fundamental understanding of the structure and pathways of complexation-driven assemblies, and raise intriguing prospects for gel formation at extraordinarily low concentrations, with applications in tissue engineering, agriculture, water purification and theranostics.« less

Gel phase formation in dilute triblock copolyelectrolyte complexes

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

Srivastava, Samanvaya; Andreev, Marat; Levi, Adam E.

Assembly of oppositely charged triblock copolyelectrolytes into phase-separated gels at low polymer concentrations (<1% by mass) has been observed in scattering experiments and molecular dynamics simulations. Here we show that in contrast to uncharged, amphiphilic block copolymers that form discrete micelles at low concentrations and enter a phase of strongly interacting micelles in a gradual manner with increasing concentration, the formation of a dilute phase of individual micelles is prevented in polyelectrolyte complexation-driven assembly of triblock copolyelectrolytes. Gel phases form and phase separate almost instantaneously on solvation of the copolymers. Furthermore, molecular models of self-assembly demonstrate the presence of oligo-chainmore » aggregates in early stages of copolyelectrolyte assembly, at experimentally unobservable polymer concentrations. Finally, our discoveries contribute to the fundamental understanding of the structure and pathways of complexation-driven assemblies, and raise intriguing prospects for gel formation at extraordinarily low concentrations, with applications in tissue engineering, agriculture, water purification and theranostics.« less

Gel phase formation in dilute triblock copolyelectrolyte complexes

DOE PAGES

Srivastava, Samanvaya; Andreev, Marat; Levi, Adam E.; ...

2017-02-23

Assembly of oppositely charged triblock copolyelectrolytes into phase-separated gels at low polymer concentrations (<1% by mass) has been observed in scattering experiments and molecular dynamics simulations. Here we show that in contrast to uncharged, amphiphilic block copolymers that form discrete micelles at low concentrations and enter a phase of strongly interacting micelles in a gradual manner with increasing concentration, the formation of a dilute phase of individual micelles is prevented in polyelectrolyte complexation-driven assembly of triblock copolyelectrolytes. Gel phases form and phase separate almost instantaneously on solvation of the copolymers. Furthermore, molecular models of self-assembly demonstrate the presence of oligo-chainmore » aggregates in early stages of copolyelectrolyte assembly, at experimentally unobservable polymer concentrations. Finally, our discoveries contribute to the fundamental understanding of the structure and pathways of complexation-driven assemblies, and raise intriguing prospects for gel formation at extraordinarily low concentrations, with applications in tissue engineering, agriculture, water purification and theranostics.« less

Gel Phase Formation in Dilute Triblock Copolyelectrolyte Complexes

NASA Astrophysics Data System (ADS)

Srivastava, Samanvaya; Andreev, Marat; Prabhu, Vivek; de Pablo, Juan; Tirrell, Matthew

Assembly of oppositely charged triblock copolyelectrolytes into phase-separated gels at extremely low polymer concentrations (<1 % by mass) has been observed in scattering experiments and molecular dynamics simulations. In contrast to uncharged, amphiphilic block copolymers that form discrete micelles at low concentrations and enter a phase of strongly interacting micelles in a gradual manner with increasing polymer concentrations, the formation of a dilute phase of individual micelles is prevented in polyelectrolyte complexation-driven assemblies of triblock copolyelectrolytes. Gel phases form and phase separate almost instantaneously upon solvation of the copolymers. Furthermore, molecular models of self-assembly demonstrate the presence of oligo-chain aggregates in early stages of triblock copolyelectrolyte assembly, at experimentally unobservable polymer concentrations. Our discoveries not only contribute to our fundamental understanding of the structure and pathways of complexation driven assemblies, but also raise intriguing prospects for formation of gel structures at extraordinarily low concentrations, with applications in tissue engineering, agriculture, water purification and theranostics.

Gel phase formation in dilute triblock copolyelectrolyte complexes

NASA Astrophysics Data System (ADS)

Srivastava, Samanvaya; Andreev, Marat; Levi, Adam E.; Goldfeld, David J.; Mao, Jun; Heller, William T.; Prabhu, Vivek M.; de Pablo, Juan J.; Tirrell, Matthew V.

2017-02-01

Assembly of oppositely charged triblock copolyelectrolytes into phase-separated gels at low polymer concentrations (<1% by mass) has been observed in scattering experiments and molecular dynamics simulations. Here we show that in contrast to uncharged, amphiphilic block copolymers that form discrete micelles at low concentrations and enter a phase of strongly interacting micelles in a gradual manner with increasing concentration, the formation of a dilute phase of individual micelles is prevented in polyelectrolyte complexation-driven assembly of triblock copolyelectrolytes. Gel phases form and phase separate almost instantaneously on solvation of the copolymers. Furthermore, molecular models of self-assembly demonstrate the presence of oligo-chain aggregates in early stages of copolyelectrolyte assembly, at experimentally unobservable polymer concentrations. Our discoveries contribute to the fundamental understanding of the structure and pathways of complexation-driven assemblies, and raise intriguing prospects for gel formation at extraordinarily low concentrations, with applications in tissue engineering, agriculture, water purification and theranostics.

The prevalence of interdigital erythrasma: a prospective study from an outpatient clinic in Turkey.

PubMed

Polat, Muhterem; İlhan, Mustafa N

2015-03-01

Erythrasma is a superficial skin infection caused by Corynebacterium minutissimum . Interdigital erythrasma is the most common form and is easily confused with tinea pedis. The aim of this study was to determine the prevalence of interdigital erythrasma in patients with clinically suspected tinea pedis. This study was performed between January 1, 2011, and January 31, 2012. It included 182 patients who presented with concerns about interdigital lesions. All of the patients were examined with a Wood's lamp, and smears were stained with Gram's method. Direct examination with 20% potassium hydroxide was performed. Of 182 patients with interdigital lesions, 73 (40.1%) were diagnosed as having erythrasma. The mean ± SD age of the patients with erythrasma was 45.52 ± 10.83 years (range, 22-70 years). Most of the patients with erythrasma were women (56.2%). The most often clinical finding was desquamation. Using only Wood's lamp examination or Gram's staining resulted in 31 (42.5%) or 14 (19.2%) positive patients, respectively. Using Wood's lamp examination and Gram's staining concurrently resulted in 28 positive patients (38.4%). Interdigital erythrasma is a common condition and can be difficult to differentiate from tinea pedis. Simple and rapid diagnosis can be made with Wood's lamp examination, but Gram's staining is also a useful method, especially in patients with negative Wood's lamp examination findings.

Gel-like properties of MCM-41 material and its transformation to MCM-50 in a caustic alkaline surround

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

Saputra, Hens; Othman, Raihan, E-mail: raihan@iium.edu.my; Sutjipto, A.G.E.

2012-03-15

Highlights: Black-Right-Pointing-Pointer MCM-41 material transforms gradually into MCM-50 lamellar gel upon controlled exposure to 6 M KOH. Black-Right-Pointing-Pointer The formation of MCM-50 ordered gel structure occurs at KOH weight content of 40-70 wt. %. Black-Right-Pointing-Pointer MCM gel phase shows pseudoplastic behavior and possesses homogeneous matrix texture. -- Abstract: MCM-41 material, prepared by sol-gel method, reveals gel-like properties in a caustic alkaline environment, i.e., 6 M potassium hydroxide (KOH) electrolyte. The gellation of MCM-41 starts at a KOH weight ratio of 40 wt.%. The structural change of the material is verified with X-Ray diffractograms and supported by observation using Scanning Electronmore » Microscope (SEM). As the KOH weight ratio increases, the MCM-41 hexagonal arrays structure gradually transforms into MCM-50 lamellar structure before disappearing completely at 80 wt.% KOH. The MCM gel phase is further characterized by rotational viscometry and texture analysis. The gel phase shows shear thinning or pseudoplastic behavior and possesses homogeneous matrix structure.« less

Association of athlete's foot with cellulitis of the lower extremities: diagnostic value of bacterial cultures of ipsilateral interdigital space samples.

PubMed

Semel, J D; Goldin, H

1996-11-01

We performed a study to determine how often patients with cellulitis of the lower extremities in the absence of trauma, peripheral vascular disease, or chronic open ulcers have ipsilateral interdigital athlete's foot and whether cultures of samples from the involved interdigital spaces would yield potentially pathogenic bacteria. Athlete's foot was present in 20 (83%) of 24 episodes of cellulitis that were studied. Cultures of samples from interdigital spaces yielded Beta-hemolytic streptococci in 17 (85%) of 20 cases, Staphylococcus aureus in 9 (45%) of 20 cases, and gram-negative rods in 7 (35%) of 20 cases. Only Beta-hemolytic streptococci were recovered significantly more often from patients than from a group of controls with athlete's foot who did not have cellulitis (P < .01). Athlete's foot may be a common predisposing condition for cellulitis of the lower extremities. In comparison with attempts at microbiological diagnosis such as aspiration and/or biopsy of the area of cellulitis, cultures of samples from the interdigital spaces combined with serial determinations of antistreptolysin titers may offer a simpler noninvasive method of microbiological diagnosis.

Stability Conditions and Mechanism of Cream Soaps: Effect of Polyols.

PubMed

Sagitani, Hiromichi; Komoriya, Masumi

2015-01-01

Fatty acids, fatty acid potassium soaps, polyols and water are essential ingredients for producing stable cream soaps. The solution behavior of the above four components system has been studied to elucidate the effect of four sorts of polyols (glycerol, 1,3-butylene glycol, polyethylene glycol 400 and dipropylene glycol) on the stability of cream soaps. It has been revealed that the lamellar liquid crystalline one-phase converted to a two-phase of a lamellar phase and an isotropic aqueous solution by the addition of a few percent of 1,3-butylene glycol, polyethylene glycol 400 and dipropylene glycol, whereas the lamellar one-phase was remained by about 50 wt% of glycerol in the aqueous solution. The X-ray data at room temperature showed that the existence of 1:1 acid soap (1:1 mole ratio of potassium soap/fatty acid) crystals in the 1,3-butylene glycol, polyethylene glycol 400 and dipropylene glycol systems, whereas that the coexistence of 1:1 acid soap crystal and a lamellar gel phase (swelled lamellar gel structure) in the glycerol system. The phase transition peaks from coagel to gel (Tgel) and from gel to liquid state (Tc) were appeared in the above four polyol systems by DSC measurements. It was confirmed from the combined data of SAXS and DSC that the existence of anhydrous 1:1 acid soap gels (or with small amount of bound water) in the all polyol systems, whereas the coexistence of the anhydrate gel and the swelled gel with a lot of intermediate water in the only glycerol system. This swelled gel structure would be contributed to stabilize the dispersed anhydrate acid soap crystals in cream soaps.

Volume phase transitions of cholesteric liquid crystalline gels.

PubMed

Matsuyama, Akihiko

2015-05-07

We present a mean field theory to describe anisotropic deformations of a cholesteric elastomer without solvent molecules and a cholesteric liquid crystalline gel immersed in isotropic solvents at a thermal equilibrium state. Based on the neoclassical rubber theory of nematic elastomers, we derive an elastic energy and a twist distortion energy, which are important to determine the shape of a cholesteric elastomer (or gel). We demonstrate that when the elastic energy dominates in the free energy, the cholesteric elastomer causes a spontaneous compression in the pitch axis and elongates along the director on the plane perpendicular to the pitch axis. Our theory can qualitatively describe the experimental results of a cholesteric elastomer. We also predict the first-order volume phase transitions and anisotropic deformations of a gel at the cholesteric-isotropic phase transition temperature. Depending on a chirality of a gel, we find a prolate or oblate shape of cholesteric gels.

Ultrafast photoinduced electron transfer in the micelle and the gel phase of a PEO-PPO-PEO triblock copolymer

NASA Astrophysics Data System (ADS)

Mandal, Ujjwal; Ghosh, Subhadip; Dey, Shantanu; Adhikari, Aniruddha; Bhattacharyya, Kankan

2008-04-01

Ultrafast photoinduced electron transfer (PET) from N,N-dimethylaniline (DMA) to coumarin dyes is studied in the micelle and the gel phase of a triblock copolymer, (PEO)20-(PPO)70-(PEO)20 (Pluronic P123) by picosecond and femtosecond emission spectroscopies. The rate of PET in a P123 micelle and gel is found to be nonexponential and faster than the slow components of solvation dynamics. In a P123 micelle and gel, PET occurs on multiple time scales ranging from a subpicosecond time scale to a few nanoseconds. In the gel phase, the highest rate constant (9.3×109M-1s-1) of ET for C152 is about two times higher than that (3.8×109M-1s-1) observed in micelle phase. The ultrafast components of electron transfer (ET) exhibits a bell shaped dependence with the free energy change which is similar to the Marcus inversion. Possible reasons for slower PET in P123 micelle compared to other micelles and relative to P123 gel are discussed.

Conductometric Sensors for Monitoring Degradation of Automotive Engine Oil†

PubMed Central

Latif, Usman; Dickert, Franz L.

2011-01-01

Conductometric sensors have been fabricated by applying imprinted polymers as receptors for monitoring engine oil quality. Titania and silica layers are synthesized via the sol-gel technique and used as recognition materials for acidic components present in used lubricating oil. Thin-film gold electrodes forming an interdigitated structure are used as transducers to measure the conductance of polymer coatings. Optimization of layer composition is carried out by varying the precursors, e.g., dimethylaminopropyltrimethoxysilane (DMAPTMS), and aminopropyl-triethoxysilane (APTES). Characterization of these sensitive materials is performed by testing against oil oxidation products, e.g., carbonic acids. The results depict that imprinted aminopropyltriethoxysilane (APTES) polymer is a promising candidate for detecting the age of used lubricating oil. In the next strategy, polyurethane-nanotubes composite as sensitive material is synthesized, producing appreciable differentiation pattern between fresh and used oils at elevated temperature with enhanced sensitivity. PMID:22164094

Out-of-water constitutional self-organization of chitosan-cinnamaldehyde dynagels.

PubMed

Marin, Luminita; Moraru, Simona; Popescu, Maria-Cristina; Nicolescu, Alina; Zgardan, Cristina; Simionescu, Bogdan C; Barboiu, Mihail

2014-04-14

An investigation of the constitutional adaptive gelation process of chitosan/cinnamaldehyde (C/Cy) dynagels is reported. These gels generate timely variant macroscopic organization across extended scales. In the first stage, imine-bond formation takes place "in-water" and generates low-ordered hydrogels. The progressive formation of imine bonds further induces "out-of-water" increased reactivity within interdigitated hydrophobic self-assembled layers of Cy, with a protecting environmental effect against hydrolysis and that leads to the stabilization of the imine bonds. The hydrophobic swelling due to Cy layers at the interfaces reaches a critical step when lamellar self-organized hybrids are generated (24 hours). This induces an important restructuration of the hydrogels on the micrometric scale, thus resulting in the formation of highly ordered microporous xerogel morphologies of high potential interest for chemical separations, drug delivery, and sensors. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

3D Printing of Carbon Nanotubes-Based Microsupercapacitors.

PubMed

Yu, Wei; Zhou, Han; Li, Ben Q; Ding, Shujiang

2017-02-08

A novel 3D printing procedure is presented for fabricating carbon-nanotubes (CNTs)-based microsupercapacitors. The 3D printer uses a CNTs ink slurry with a moderate solid content and prints a stream of continuous droplets. Appropriate control of a heated base is applied to facilitate the solvent removal and adhesion between printed layers and to improve the structure integrity without structure delamination or distortion upon drying. The 3D-printed electrodes for microsupercapacitors are characterized by SEM, laser scanning confocal microscope, and step profiler. Effect of process parameters on 3D printing is also studied. The final solid-state microsupercapacitors are assembled with the printed multilayer CNTs structures and poly(vinyl alcohol)-H 3 PO 4 gel as the interdigitated microelectrodes and electrolyte. The electrochemical performance of 3D printed microsupercapacitors is also tested, showing a significant areal capacitance and excellent cycle stability.

Sol-Gel Glasses

NASA Technical Reports Server (NTRS)

Mukherjee, S. P.

1985-01-01

Multicomponent homogeneous, ultrapure noncrystalline gels/gel derived glasses are promising batch materials for the containerless glass melting experiments in microgravity. Hence, ultrapure, homogeneous gel precursors could be used to: (1) investigate the effect of the container induced nucleation on the glass forming ability of marginally glass forming compositions; and (2) investigate the influence of gravity on the phase separation and coarsening behavior of gel derived glasses in the liquid-liquid immiscibility zone of the nonsilicate systems having a high density phase. The structure and crystallization behavior of gels in the SiO2-GeO2 as a function of gel chemistry and thermal treatment were investigated. As are the chemical principles involved in the distribution of a second network former in silica gel matrix being investigated. The procedures for synthesizing noncrystalline gels/gel-monoliths in the SiO2-GeO2, GeO2-PbO systems were developed. Preliminary investigations on the levitation and thermal treatment of germania silicate gel-monoliths in the Pressure Facility Acoustic Levitator were done.

High-frequency shear-horizontal surface acoustic wave sensor

DOEpatents

Branch, Darren W

2013-05-07

A Love wave sensor uses a single-phase unidirectional interdigital transducer (IDT) on a piezoelectric substrate for leaky surface acoustic wave generation. The IDT design minimizes propagation losses, bulk wave interferences, provides a highly linear phase response, and eliminates the need for impedance matching. As an example, a high frequency (.about.300-400 MHz) surface acoustic wave (SAW) transducer enables efficient excitation of shear-horizontal waves on 36.degree. Y-cut lithium tantalate (LTO) giving a highly linear phase response (2.8.degree. P-P). The sensor has the ability to detect at the pg/mm.sup.2 level and can perform multi-analyte detection in real-time. The sensor can be used for rapid autonomous detection of pathogenic microorganisms and bioagents by field deployable platforms.

High-frequency shear-horizontal surface acoustic wave sensor

DOEpatents

Branch, Darren W

2014-03-11

A Love wave sensor uses a single-phase unidirectional interdigital transducer (IDT) on a piezoelectric substrate for leaky surface acoustic wave generation. The IDT design minimizes propagation losses, bulk wave interferences, provides a highly linear phase response, and eliminates the need for impedance matching. As an example, a high frequency (.about.300-400 MHz) surface acoustic wave (SAW) transducer enables efficient excitation of shear-horizontal waves on 36.degree. Y-cut lithium tantalate (LTO) giving a highly linear phase response (2.8.degree. P-P). The sensor has the ability to detect at the pg/mm.sup.2 level and can perform multi-analyte detection in real-time. The sensor can be used for rapid autonomous detection of pathogenic microorganisms and bioagents by field deployable platforms.

Superharmonic resonances in a two-dimensional non-linear photonic-crystal nano-electro-mechanical oscillator

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

Chowdhury, A.; Yeo, I.; Tsvirkun, V.

2016-04-18

We investigate the non-linear mechanical dynamics of a nano-optomechanical mirror formed by a suspended membrane pierced by a photonic crystal. By applying to the mirror a periodic electrostatic force induced by interdigitated electrodes integrated below the membrane, we evidence superharmonic resonances of our nano-electro-mechanical system; the constant phase shift of the oscillator across the resonance tongues is observed on the onset of principal harmonic and subharmonic excitation regimes.

Effect of the barometric phase transition of a DMPA bilayer on the lipid/water interface. An atomistic description by molecular dynamics simulation.

PubMed

Casares, J J Giner; Camacho, L; Romero, M T Martín; Cascales, J J López

2007-12-13

Understanding the structure and dynamics of phospholipid bilayers is of fundamental relevance in biophysics, biochemistry, and chemical physics. Lipid Langmuir monolayers are used as a model of lipid bilayers, because they are much more easily studied experimentally, although some authors question the validity of this model. With the aim of throwing light on this debate, we used molecular dynamics simulations to obtain an atomistic description of a membrane of dimyristoylphosphatidic acid under different surface pressures. Our results show that at low surface pressure the interdigitation between opposite lipids (that is, back-to-back interactions) controls the system structure. In this setting and due to the absence of this effect in the Langmuir monolayers, the behavior between these two systems differs considerably. However, when the surface pressure increases the lipid interdigitation diminishes and so monolayer and bilayer behavior converges. In this work, four computer simulations were carried out, subjecting the phospholipids to lateral pressures ranging from 0.17 to 40 mN/m. The phospholipids were studied in their charged state because this approach is closer to the experimental situation. Special attention was paid to validating our simulation results by comparison with available experimental data, therebeing in general excellent agreement between experimental and simulation data. In addition, the properties of the lipid/solution interface associated with the lipid barometric phase transition were studied.

Numerical modelling and experimental study of liquid evaporation during gel formation

NASA Astrophysics Data System (ADS)

Pokusaev, B. G.; Khramtsov, D. P.

2017-11-01

Gels are promising materials in biotechnology and medicine as a medium for storing cells for bioprinting applications. Gel is a two-phase system consisting of solid medium and liquid phase. Understanding of a gel structure evolution and gel aging during liquid evaporation is a crucial step in developing new additive bioprinting technologies. A numerical and experimental study of liquid evaporation was performed. In experimental study an evaporation process of an agarose gel layer located on Petri dish was observed and mass difference was detected using electronic scales. Numerical model was based on a smoothed particle hydrodynamics method. Gel in a model was represented as a solid-liquid system and liquid evaporation was modelled due to capillary forces and heat transfer. Comparison of experimental data and numerical results demonstrated that model can adequately represent evaporation process in agarose gel.

Low-frequency and wideband vibration energy harvester with flexible frame and interdigital structure

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

Li, Pengwei, E-mail: lipengwei@tyut.edu.cn; Wang, Yanfen; Luo, Cuixian

2015-04-15

As an alternative to traditional cantilever beam structures and their evolutions, a flexible beam based, interdigital structure, vibration energy harvester has been presented and investigated. The proposed interdigital-shaped oscillator consists of a rectangular flexible frame and series of cantilever beams interdigitally bonded to it. In order to achieve low frequency and wide-bandwidth harvesting, Young’s modulus of materials, frame size and the amount of the cantilevers have been studied systematically. The measured frequency responses of the designed device (PDMS frame, quintuple piezoelectric cantilever beams) show a 460% increase in bandwidth below 80Hz. When excited at an acceleration of 1.0 g, themore » energy harvester achieves to a maximum open-circuit voltage of 65V, and the maximum output power 4.5 mW.« less

Starbursts and Wispy Drops : Surfactants Spreading on Gel Substrates

NASA Astrophysics Data System (ADS)

Mukhopadhyay, Shomeek; Daniels, Karen; Behringer, Robert

2005-11-01

We report a phase diagram for a novel instability seen in drops of nonionic surfactant solution (Triton X-305) spreading on viscoelastic agar gel substrate . This system allows us to examine the effect of varying the effective fluidity/stiffness of aqueous substrates. The morphology is strongly affected by the substrate fluidity, ranging from spreading starbursts of arms on weak gels, to wispy drops on intermediate strength gels, to circular drops on stiff gels. We analyze the dynamics of spreading in the starburst phase, where the arm length grows as t ^3/4 at early times, independent of the gel strength and surfactant concentration. The number of arms is proportional to the surfactant concentration and inversely proportional to the gel strength. Ongoing work is exploring the effects of changing the drop volume.

Continuous monitoring of enzymatic activity within native electrophoresis gels: Application to mitochondrial oxidative phosphorylation complexes

PubMed Central

Covian, Raul; Chess, David; Balaban, Robert S.

2012-01-01

Native gel electrophoresis allows the separation of very small amounts of protein complexes while retaining aspects of their activity. In-gel enzymatic assays are usually performed by using reaction-dependent deposition of chromophores or light scattering precipitates quantified at fixed time points after gel removal and fixation, limiting the ability to analyze enzyme reaction kinetics. Herein, we describe a custom reaction chamber with reaction media recirculation and filtering and an imaging system that permits the continuous monitoring of in-gel enzymatic activity even in the presence of turbidity. Images were continuously collected using time-lapse high resolution digital imaging, and processing routines were developed to obtain kinetic traces of the in-gel activities and analyze reaction time courses. This system also permitted the evaluation of enzymatic activity topology within the protein bands of the gel. This approach was used to analyze the reaction kinetics of two mitochondrial complexes in native gels. Complex IV kinetics showed a short initial linear phase where catalytic rates could be calculated, whereas Complex V activity revealed a significant lag phase followed by two linear phases. The utility of monitoring the entire kinetic behavior of these reactions in native gels, as well as the general application of this approach, is discussed. PMID:22975200

Continuous monitoring of enzymatic activity within native electrophoresis gels: application to mitochondrial oxidative phosphorylation complexes.

PubMed

Covian, Raul; Chess, David; Balaban, Robert S

2012-12-01

Native gel electrophoresis allows the separation of very small amounts of protein complexes while retaining aspects of their activity. In-gel enzymatic assays are usually performed by using reaction-dependent deposition of chromophores or light-scattering precipitates quantified at fixed time points after gel removal and fixation, limiting the ability to analyze the enzyme reaction kinetics. Herein, we describe a custom reaction chamber with reaction medium recirculation and filtering and an imaging system that permits the continuous monitoring of in-gel enzymatic activity even in the presence of turbidity. Images were continuously collected using time-lapse high-resolution digital imaging, and processing routines were developed to obtain kinetic traces of the in-gel activities and analyze reaction time courses. This system also permitted the evaluation of enzymatic activity topology within the protein bands of the gel. This approach was used to analyze the reaction kinetics of two mitochondrial complexes in native gels. Complex IV kinetics showed a short initial linear phase in which catalytic rates could be calculated, whereas Complex V activity revealed a significant lag phase followed by two linear phases. The utility of monitoring the entire kinetic behavior of these reactions in native gels, as well as the general application of this approach, is discussed. Published by Elsevier Inc.

Design and simulation study of high frequency response for surface acoustic wave device by using CST software

NASA Astrophysics Data System (ADS)

Zakaria, M. R.; Hashim, U.; Amin, Mohd Hasrul I. M.; Ayub, R. Mat; Hashim, M. N.; Adam, T.

2015-05-01

This paper focuses on the enhancement and improvement of the Surface Acoustic Wave (SAW) device performance. Due to increased demand in the international market for biosensor product, the product must be emphasized in terms of quality. However, within the technological advances, demand for device with low cost, high efficiency and friendly-user preferred. Surface Acoustic Wave (SAW) device with the combination of pair electrode know as Interdigital Transducer (IDT) was fabricated on a piezoelectric substrate. The design of Interdigital Transducer (IDT) parameter is changes in several sizes and values for which it is able to provide greater efficiency in sensing sensitivity by using process simulation with CST STUDIO Suite software. In addition, Interdigital Transducer (IDT) parameters also changed to be created the products with a smaller size and easy to handle where it also reduces the cost of this product. Parameter values of an Interdigital Transducer (IDT) will be changed in the design is the total number of fingers pair, finger length, finger width and spacing, aperture and also the thickness of the Interdigital Transducer (IDT). From the result, the performance of the sensor is improved significantly after modification is done.

Lectin histochemistry of the interdigital gland in the Japanese serow (Capricornis crispus) in winter.

PubMed Central

Atoji, Y; Suzuki, Y; Sugimura, M

1988-01-01

The interdigital gland of the Japanese serow was examined by histological and lectin histochemical techniques. The gland is composed of a thin-walled pouch and a duct. Both regions contain sebaceous and apocrine glands, but the development of each component was significantly less marked than those of the skin in the region. In particular, only a small amount of sebaceous and apocrine glandular elements was found in the pouch, although they were more abundant in the duct. Histochemical staining of the sebaceous and apocrine glands showed similar reactions to six lectins except for UEA in the interdigital gland and digital surface skin. UEA reacted with the apocrine part of the interdigital gland, but not with the gland in the digital surface skin. In addition, tubules in the apocrine gland revealed eight different staining patterns with UEA. These stainings possibly represent a cyclic activity of glandular tubules and suggest that the apocrine portion of the interdigital gland has a different function from that of the body skin. Images Fig. 1 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 PMID:3254889

Characterization methodology for lead zirconate titanate thin films with interdigitated electrode structures

NASA Astrophysics Data System (ADS)

Nigon, R.; Raeder, T. M.; Muralt, P.

2017-05-01

The accurate evaluation of ferroelectric thin films operated with interdigitated electrodes is quite a complex task. In this article, we show how to correct the electric field and the capacitance in order to obtain identical polarization and CV loops for all geometrical variants. The simplest model is compared with corrections derived from Schwartz-Christoffel transformations, and with finite element simulations. The correction procedure is experimentally verified, giving almost identical curves for a variety of gaps and electrode widths. It is shown that the measured polarization change corresponds to the average polarization change in the center plane between the electrode fingers, thus at the position where the electric field is most homogeneous with respect to the direction and size. The question of maximal achievable polarization in the various possible textures, and compositional types of polycrystalline lead zirconate titanate thin films is revisited. In the best case, a soft (110) textured thin film with the morphotropic phase boundary composition should yield a value of 0.95Ps, and in the worst case, a rhombohedral (100) textured thin film should deliver a polarization of 0.74Ps.

Phase equilibrium and preparation, crystallization and viscous sintering of glass in the alumina-silica-lanthanum phosphate system

NASA Astrophysics Data System (ADS)

He, Feng

The phase equilibrium, viscosity of melt-quenched glasses, and processing of sol-gel glasses of the alumina-silica-lanthanum phosphate system were studied. These investigations were directed towards serving the objective of synthesizing nano-structured ceramic-matrix-composites via controlled crystallization of glass precursors. The thermal stability, phase equilibrium, and liquidus temperatures of the alumina- and mullite-lanthanum phosphate systems are determined. An iridium wire heater was constructed to anneal samples up to 2200°C. Phosphorus evaporation losses were significant at high temperatures, especially over 1800°C. The tentative phase diagrams of the two quasi-binary systems were presented. The viscosity of the melt-quenched mullite-lanthanum phosphate glasses was measured by three different methods, including viscous sintering of glass powder compacts, neck formation between two Frenkel glass beads, and thermal analysis of the glass transition. Improved methodologies were developed for applying the interpretative mathematical models to the results of the sintered powder and thermal analytical experiments. Good agreement was found between all three methods for both absolute values and temperature dependence. A sol-gel process was developed as a low temperature route to producing glasses. A unique, single phase mullite gel capable of low temperature (575°C) mullitization was made from tetraethoxysilane and aluminum isopropoxide at room temperature in three days. Low temperature crystallization was attributed to the avoidance of phase segregation during gel formation and annealing. This was greatly enhanced by a combination of low temperature preheating in the amorphous state, a high heating rate during crystallization and low water content. The Al2O3 content in mullite (61-68 mol%) depended on the highest annealing temperature. Two mullite-lanthanum phosphate gels were made based upon modifying the chemical procedures used for the homogeneous single phase and heterogeneous diphasic mullite gels from same starting chemicals. Amorphous powders were obtained after optimized calcinations. Their different crystallization routes and sintering behavior were investigated and correlated with the different homogeneities of precursor gels. Structurally stable open, porous ceramics (up to 80% porosity) were produced from the single-phase gel derived powder, where gases exsolved during calcination caused foaming coincident with sintering. Translucent, dense glass ceramic was made from the calcined diphasic gel by hot-pressing.

CORRIGENDUM: Dielectric dispersion of BaxSr1 - xTiO3 thin film with parallel-plate and coplanar interdigital electrodes Dielectric dispersion of BaxSr1 - xTiO3 thin film with parallel-plate and coplanar interdigital electrodes

NASA Astrophysics Data System (ADS)

Zhang, Xiao-Yu; Song, Qing; Xu, Feng; Sheng, Su; Wang, Peng; Ong, C. K.

2010-03-01

Figures 1, 2 and 5 of this paper are reprinted from the authors' previous paper, Zhang X-Y, Wang P, Sheng S, Xu F and Ong C K 2008 Ferroelectric BaxSr1 - xTiO3 thin-film varactors with parallel plate and interdigital electrodes for microwave applications J. Appl. Phys. 104 124110, copyright 2008, with permission from the American Institute of Physics.

Microscopic Description of Thermodynamics of Lipid Membrane at Liquid-Gel Phase Transition

NASA Astrophysics Data System (ADS)

Kheyfets, B.; Galimzyanov, T.; Mukhin, S.

2018-05-01

A microscopic model of the lipid membrane is constructed that provides analytically tractable description of the physical mechanism of the first order liquid-gel phase transition. We demonstrate that liquid-gel phase transition is cooperative effect of the three major interactions: inter-lipid van der Waals attraction, steric repulsion and hydrophobic tension. The model explicitly shows that temperature-dependent inter-lipid steric repulsion switches the system from liquid to gel phase when the temperature decreases. The switching manifests itself in the increase of lateral compressibility of the lipids as the temperature decreases, making phase with smaller area more preferable below the transition temperature. The model gives qualitatively correct picture of abrupt change at transition temperature of the area per lipid, membrane thickness and volume per hydrocarbon group in the lipid chains. The calculated dependence of phase transition temperature on lipid chain length is in quantitative agreement with experimental data. Steric repulsion between the lipid molecules is shown to be the only driver of the phase transition, as van der Waals attraction and hydrophobic tension are weakly temperature dependent.

CO2 Responsive Imidazolium-Type Poly(Ionic Liquid) Gels.

PubMed

Zhang, Jing; Xu, Dan; Guo, Jiangna; Sun, Zhe; Qian, Wenjing; Zhang, Ye; Yan, Feng

2016-07-01

Poly(ionic liquid) (PIL) gels with CO2 stimulus responsiveness have been synthesized through the copolymerization of an imidazolium-type ionic liquid monomer with 2-(dimethyl amino) ethyl methacrylate. Upon bubbling with CO2 gas, the prepared PIL solution is converted to a transparent and stable gel, which can be turned back to the initial solution state after N2 bubbling. The reversible sol-gel phase transition behavior is proved by the reversible values of viscosity and ionic conductivity. The possible mechanism for such a reversible sol-gel phase transition is demonstrated by NMR, conductivity, and rheological measurements. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ternary Phase-Separation Investigation of Sol-Gel Derived Silica from Ethyl Silicate 40

PubMed Central

Wang, Shengnan; Wang, David K.; Smart, Simon; Diniz da Costa, João C.

2015-01-01

A ternary phase-separation investigation of the ethyl silicate 40 (ES40) sol-gel process was conducted using ethanol and water as the solvent and hydrolysing agent, respectively. This oligomeric silica precursor underwent various degrees of phase separation behaviour in solution during the sol-gel reactions as a function of temperature and H2O/Si ratios. The solution composition within the immiscible region of the ES40 phase-separated system shows that the hydrolysis and condensation reactions decreased with decreasing reaction temperature. A mesoporous structure was obtained at low temperature due to weak drying forces from slow solvent evaporation on one hand and formation of unreacted ES40 cages in the other, which reduced network shrinkage and produced larger pores. This was attributed to the concentration of the reactive sites around the phase-separated interface, which enhanced the condensation and crosslinking. Contrary to dense silica structures obtained from sol-gel reactions in the miscible region, higher microporosity was produced via a phase-separated sol-gel system by using high H2O/Si ratios. This tailoring process facilitated further condensation reactions and crosslinking of silica chains, which coupled with stiffening of the network, made it more resistant to compression and densification. PMID:26411484

A cell sorting and trapping microfluidic device with an interdigital channel

NASA Astrophysics Data System (ADS)

Tu, Jing; Qiao, Yi; Xu, Minghua; Li, Junji; Liang, Fupeng; Duan, Mengqin; Ju, An; Lu, Zuhong

2016-12-01

The growing interest in cell sorting and trapping is driving the demand for high performance technologies. Using labeling techniques or external forces, cells can be identified by a series of methods. However, all of these methods require complicated systems with expensive devices. Based on inherent differences in cellular morphology, cells can be sorted by specific structures in microfluidic devices. The weir filter is a basic and efficient cell sorting and trapping structure. However, in some existing weir devices, because of cell deformability and high flow velocity in gaps, trapped cells may become stuck or even pass through the gaps. Here, we designed and fabricated a microfluidic device with interdigital channels for cell sorting and trapping. The chip consisted of a sheet of silicone elastomer polydimethylsiloxane and a sheet of glass. A square-wave-like weir was designed in the middle of the channel, comprising the interdigital channels. The square-wave pattern extended the weir length by three times with the channel width remaining constant. Compared with a straight weir, this structure exhibited a notably higher trapping capacity. Interdigital channels provided more space to slow down the rate of the pressure decrease, which prevented the cells from becoming stuck in the gaps. Sorting a mixture K562 and blood cells to trap cells demonstrated the efficiency of the chip with the interdigital channel to sort and trap large and less deformable cells. With stable and efficient cell sorting and trapping abilities, the chip with an interdigital channel may be widely applied in scientific research fields.

Very large phase shift of microwave signals in a 6 nm Hf x Zr1-x O2 ferroelectric at ±3 V

NASA Astrophysics Data System (ADS)

Dragoman, Mircea; Modreanu, Mircea; Povey, Ian M.; Iordanescu, Sergiu; Aldrigo, Martino; Romanitan, Cosmin; Vasilache, Dan; Dinescu, Adrian; Dragoman, Daniela

2017-09-01

In this letter, we report for the first time very large phase shifts of microwaves in the 1-10 GHz range, in a 1 mm long gold coplanar interdigitated structure deposited over a 6 nm Hf x Zr1-x O2 ferroelectric grown directly on a high resistivity silicon substrate. The phase shift is larger than 60° at 1 GHz and 13° at 10 GHz at maximum applied DC voltages of ±3 V, which can be supplied by a simple commercial battery. In this way, we demonstrate experimentally that the new ferroelectrics based on HfO2 could play an important role in the future development of wireless communication systems for very low power applications.

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

Morandeau, Antoine E.; White, Claire E.

Calcium–silicate–hydrate (C–S–H) gel is the main binder component in hydrated ordinary Portland cement (OPC) paste, and is known to play a crucial role in the carbonation of cementitious materials, especially for more sustainable alternatives containing supplementary cementitious materials. However, the exact atomic structural changes that occur during carbonation of C–S–H gel remain unknown. Here, we investigate the local atomic structural changes that occur during carbonation of a synthetic calcium–silicate–hydrate gel exposed to pure CO₂ vapour, using in situ X-ray total scattering measurements and subsequent pair distribution function (PDF) analysis. By analysing both the reciprocal and real-space scattering data as themore » C–S–H carbonation reaction progresses, all phases present during the reaction (crystalline and non-crystalline) have been identified and quantified, with the results revealing the emergence of several polymorphs of crystalline calcium carbonate (vaterite and calcite) in addition to the decalcified C–S–H gel. Furthermore, the results point toward residual calcium being present in the amorphous decalcified gel, potentially in the form of an amorphous calcium carbonate phase. As a result of the quantification process, the reaction kinetics for the evolution of the individual phases have been obtained, revealing new information on the rate of growth/dissolution for each phase associated with C–S–H gel carbonation. Moreover, the investigation reveals that the use of real space diffraction data in the form of PDFs enables more accurate determination of the phases that develop during complex reaction processes such as C–S–H gel carbonation in comparison to the conventional reciprocal space Rietveld analysis approach.« less

Influence of the intrinsic membrane protein bacteriorhodopsin on gel-phase domain topology in two-component phase-separated bilayers.

PubMed Central

Schram, V; Thompson, T E

1997-01-01

We have investigated the effect of the intrinsic membrane protein bacteriorhodopsin of Halobacterium halobium on the lateral organization of the lipid phase structure in the coexistence region of an equimolar mixture of dimyristoylphos-phatidylcholine and distearoylphosphatidylcholine. The fluorescence recovery after photobleaching (FRAP) technique was used to monitor the diffusion of both a lipid analog (N-(7-nitrobenzoxa-2,3-diazol-4-yl)-dimyristoylphosphatidyle thanolamine, NBD-DMPE) and fluorescein-labeled bacteriorhodopsin (Fl-BR). In the presence of bacteriorhodopsin, the mobile fractions of the two fluorescent probes display a shift of the percolation threshold toward lower temperatures (larger gel-phase fractions), independent of the protein concentration, from 43 degrees C (without bacteriorhodopsin) to 39 degrees C and 41 degrees C for NBD-DMPE and Fl-BR, respectively. Moreover, in the presence of bacteriorhodopsin, the gel-phase domains are much less efficient in restricting the diffusion of both probes than they are in the absence of the protein in the two-phase coexistence region. Bacteriorhodopsin itself, however, obstructs diffusion of NBD-DMPE and Fl-BR to about the same extent in the fluid phase of the two-phase region as it does in the homogeneous fluid phase. These observations suggest that 1) the protein induces the formation of much larger and/or more centrosymmetrical gel-phase domains than those formed in its absence, and 2) bacteriorhodopsin partitions almost equally between the coexisting fluid and gel phases. Although the molecular mechanisms involved are not clear, this phenomenon is fully consistent with the effect of the transmembrane peptide pOmpA of Escherichia coli investigated by electron spin resonance in the same lipid system. PMID:9129824

Morphology of molecular soy protein fractions in binary composite gels.

PubMed

Kasapis, Stefan; Tay, Sok Li

2009-08-04

We investigate the structural properties of gels of binary mixtures of the three major soy protein fractions: 11S, 7S, and 2S. Gels are formed at 25 degrees C in the presence of glucono-delta-lactone and studied using a combination of dynamic rheology and scanning electron microscopy. The theological data was then modeled using a blending-law approach that yields insights into the solvent distribution between the gelled protein fractions and first-order reaction kinetics that follow the gelation process of the single fractions and their mixtures. Gelled mixtures of 11S and 7S yielded enhanced network strength with increasing solid content; in these gels, 50% more solvent partitioned into the 11S phase as compared to that in the 7S phase. In contrast, the addition of small-molecular-weight counterpart 2S to either 11S or 7S results in a catastrophic drop in the values of the overall strength of the mixture. The unexpected phase behavior has been rationalized on the basis of the high water-holding capacity of 2S; 450% more solvent partitions preferentially into the 2S phase as compared to that in the 11S phase. As the concentration of 2S is increased relative to that of 11S or 7S, it becomes the dominant phase and entraps the polymeric segments of 11S (or 7S), thus preventing them from becoming the structural knots of the gel. In addition to the solvent distribution in the gel, the rates of gelation differ markedly between 11S and 2S (with the 11S rate of gelation being up to 2 orders of magnitude greater); a fixed 11S concentration, the rate of gelation decreases with increasing amounts of 2S, further confirming that the latter essentially becomes the dominant phase in the composite gel.

Sol gel-derived hydroxyapatite films over porous calcium polyphosphate substrates for improved tissue engineering of osteochondral-like constructs.

PubMed

Lee, Whitaik David; Gawri, Rahul; Pilliar, Robert M; Stanford, William L; Kandel, Rita A

2017-10-15

Integration of in vitro-formed cartilage on a suitable substrate to form tissue-engineered implants for osteochondral defect repair is a considerable challenge. In healthy cartilage, a zone of calcified cartilage (ZCC) acts as an intermediary for mechanical force transfer from soft to hard tissue, as well as an effective interlocking structure to better resist interfacial shear forces. We have developed biphasic constructs that consist of scaffold-free cartilage tissue grown in vitro on, and interdigitated with, porous calcium polyphosphate (CPP) substrates. However, as CPP degrades, it releases inorganic polyphosphates (polyP) that can inhibit local mineralization, thereby preventing the formation of a ZCC at the interface. Thus, we hypothesize that coating CPP substrate with a layer of hydroxyapatite (HA) might prevent or limit this polyP release. To investigate this we tested both inorganic or organic sol-gel processing methods, asa barrier coating on CPP substrate to inhibit polyP release. Both types of coating supported the formation of ZCC in direct contact with the substrate, however the ZCC appeared more continuous in the tissue formed on the organic HA sol gel coated CPP. Tissues formed on coated substrates accumulated comparable quantities of extracellular matrix and mineral, but tissues formed on organic sol-gel (OSG)-coated substrates accumulated less polyP than tissues formed on inorganic sol-gel (ISG)-coated substrates. Constructs formed with OSG-coated CPP substrates had greater interfacial shear strength than those formed with ISG-coated and non-coated substrates. These results suggest that the OSG coating method can modify the location and distribution of ZCC and can be used to improve the mechanical integrity of tissue-engineered constructs formed on porous CPP substrates. Articular cartilage interfaces with bone through a zone of calcified cartilage. This study describes a method to generate an "osteochondral-like" implant that mimics this organization using isolated deep zone cartilage cells and a sol-gel hydroxyapatite coated bone substitute material composed of calcium polyphosphate (CPP). Developing a layer of calcified cartilage at the interface should contribute to enhancing the success of this "osteochondral-like" construct following implantation to repair cartilage defects. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Low temperature synthesis of monolithic transparent Ta2O5 gels from hydrolysis of metal alkoxide

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.

1993-01-01

Tantalum oxide gels in the form of transparent monoliths and powder were prepared from hydrolysis of tantalum pentaethoxide under controlled conditions using different mole ratios of Ta(OC2H5)5:C2H50H:H20:HCl. Alcohol acts as the mutual solvent and HCl as the deflocculating agent. For a fixed alkoxide:water:HCl ratio, time of gel formation increased with the alcohol to alkoxide mole ratio. Thermal evolution of the physical and structural changes in the gel was monitored by differential thermal analysis, thermogravimetric analysis, x-ray diffraction, and infrared spectroscopy. On heating to approximately 400 C, the amorphous gel crystallized into the low temperature orthorhombic phase Beta-Ta2O5, which transformed into the high temperature tetragonal phase Alpha-Ta2O5 when further heated to approximately 1450 C. The volume fraction of the crystalline phase increased with the firing temperature. The Alpha-Ta205 converted back into the low temperature phase, Beta-Ta2O5, on slow cooling through the transformation temperature of 1360 C indicating a slow but reversible transformation.

Palmar dermatoglyphic patterns in twins.

PubMed

Jacques, S M; Salzano, F M; Penña, H F

1977-01-01

The role of genetic factors in the determination of palmar dermatoglyphic patterns was investigated in a series of 49 MZ and 51 DZ twins, using Spearman's rank correlation and analysis of variance. Both methods indicated that the genetic effect in the distribution of patterns is highest in the interdigital III and lowest in the interdigital IV regions, the hypothenar and thenar showing intermediate values. As for interdigital II, no evaluation of genetic effects was possible using the nonparametric test, but the estimates of genetic variance indicate that inherited factors may play a relatively minor role in the pattern distribution of this area.

Development of soy lecithin based novel self-assembled emulsion hydrogels.

PubMed

Singh, Vinay K; Pandey, Preeti M; Agarwal, Tarun; Kumar, Dilip; Banerjee, Indranil; Anis, Arfat; Pal, Kunal

2015-03-01

The current study reports the development and characterization of soy lecithin based novel self-assembled emulsion hydrogels. Sesame oil was used as the representative oil phase. Emulsion gels were formed when the concentration of soy lecithin was >40% w/w. Metronidazole was used as the model drug for the drug release and the antimicrobial tests. Microscopic study showed the apolar dispersed phase in an aqueous continuum phase, suggesting the formation of emulsion hydrogels. FTIR study indicated the formation of intermolecular hydrogen bonding, whereas, the XRD study indicated predominantly amorphous nature of the emulsion gels. Composition dependent mechanical and drug release properties of the emulsion gels were observed. In-depth analyses of the mechanical studies were done using Ostwald-de Waele power-law, Kohlrausch and Weichert models, whereas, the drug release profiles were modeled using Korsmeyer-Peppas and Peppas-Sahlin models. The mechanical analyses indicated viscoelastic nature of the emulsion gels. The release of the drug from the emulsion gels was diffusion mediated. The drug loaded emulsion gels showed good antimicrobial activity. The biocompatibility test using HaCaT cells (human keratinocytes) suggested biocompatibility of the emulsion gels. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of alkyl chain length and anion size on thermal and structural properties for 1-alkyl-3-methylimidazolium hexafluorocomplex salts (C(x)MImAF6, x = 14, 16 and 18; A = P, As, Sb, Nb and Ta).

PubMed

Xu, Fei; Matsumoto, Kazuhiko; Hagiwara, Rika

2012-03-28

A series of 1-alkyl-3-methylimidazolium hexafluorocomplex salts (C(x)MImAF(6), x = 14, 16 and 18, A = P, As, Sb, Nb and Ta) have been characterized by thermal analysis, X-ray diffraction and polarized optical microscopy. A liquid crystalline mesophase is observed for all the C(16)MIm and C(18)MIm salts. The C(14)MIm(+) cation gives a liquid crystalline mesophase only with PF(6)(-). The temperature range of the liquid crystalline mesophase increases with an increase in alkyl chain length or with decrease in anion size. Single-crystal X-ray diffraction revealed that all the C(18)MImAF(6) salts (A = P, As, Sb, Nb and Ta) are isostructural with each other in the crystalline phase and have a layered structure. The interdigitated alkyl chain of the cation has a bent shape like a spoon near the imidazolium ring in the crystalline phase at -100 °C and is tilted with respect to the sheets of the imidazolium headgroups and anions. An increase of temperature increases the ratio of an all-trans conformation to the bent conformation in the crystalline phase. X-ray diffraction and polarized optical microscopy suggested that the liquid crystalline mesophase has a smectic A(2) structure. The interlayer distance increases with a decrease in the anion size since the smaller anion has a stronger coulombic interaction with the imidazolium headgroup, resulting in the decrease of the interdigitated part to give a larger layer spacing.

A fluorescence correlation spectroscopy study of the diffusion of an organic dye in the gel phase and fluid phase of a single lipid vesicle.

PubMed

Ghosh, Subhadip; Adhikari, Aniruddha; Sen Mojumdar, Supratik; Bhattacharyya, Kankan

2010-05-06

The mobility of the organic dye DCM (4-dicyanomethylene-2-methyl-6-p-dimethyl aminostyryl-4H-pyran) in the gel and fluid phases of a lipid vesicle is studied by fluorescence correlation spectroscopy (FCS). Using FCS, translational diffusion of DCM is determined in the gel phase and fluid phase of a single lipid vesicle adhered to a glass surface. The size of a lipid vesicle (average diameter approximately 100 nm) is smaller than the diffraction limited spot size (approximately 250 nm) of the microscope. Thus, the vesicle is confined within the laser focus. Three lipid vesicles (1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC), 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)) having different gel transition temperatures (-1, 23, and 41 degrees C, respectively) were studied. The diffusion coefficient of the dye DCM in bulk water is approximately 300 microm(2)/s. In the lipid vesicle, the average D(t) decreases markedly to approximately 5 microm(2)/s (approximately 60 times) in the gel phase (for DPPC at 20 degrees C) and 40 microm(2)/s ( approximately 8 times) in the fluid phase (for DLPC at 20 degrees C). This clearly demonstrates higher mobility in the fluid phase compared with the gel phase of a lipid. It is observed that the D(t) values vary from lipid to lipid and there is a distribution of D(t) values. The diffusion of the hydrophobic dye DCM (D(t) approximately 5 microm(2)/s) in the DPPC vesicle is found to be 8 times smaller than that of a hydrophilic anioinic dye C343 (D(t) approximately 40 microm(2)/s). This is attributed to different locations of the hydrophobic (DCM) and hydrophilic (C343) dyes.

Lipophilic Super-Absorbent Swelling Gels as Cleaners for Use on Weapons Systems and Platforms

DTIC Science & Technology

2011-08-18

polymer gel systems. Further research will address the post-cleaning gel removal method, the use of non- fluorinated compounds in gel synthesis, and...be proposed to address other issues including the method for removing the gels after swelling, the use of non- fluorinated compounds in gel...strength. Elimination of fluorinated compounds in the gel synthesis was the focus of this and subsequent phases of this research. TECHNICAL APPROACH

Multiple-frequency acoustic wave devices for chemical sensing and materials characterization in both gas and liquid phase

DOEpatents

Martin, S.J.; Ricco, A.J.

1993-08-10

A chemical or intrinsic physical property sensor is described comprising: (a) a substrate; (b) an interaction region of said substrate where the presence of a chemical or physical stimulus causes a detectable change in the velocity and/or an attenuation of an acoustic wave traversing said region; and (c) a plurality of paired input and output interdigitated electrodes patterned on the surface of said substrate where each of said paired electrodes has a distinct periodicity, where each of said paired electrodes is comprised of an input and an output electrode; (d) an input signal generation means for transmitting an input signal having a distinct frequency to a specified input interdigitated electrode of said plurality so that each input electrode receives a unique input signal, whereby said electrode responds to said input signal by generating an acoustic wave of a specified frequency, thus, said plurality responds by generating a plurality of acoustic waves of different frequencies; (e) an output signal receiving means for determining an acoustic wave velocity and an amplitude of said acoustic waves at several frequencies after said waves transverses said interaction region and comparing these values to an input acoustic wave velocity and an input acoustic wave amplitude to produce values for perturbations in acoustic wave velocities and for acoustic wave attenuation as a function of frequency, where said output receiving means is individually coupled to each of said output interdigitated electrode; (f) a computer means for analyzing a data stream comprising information from said output receiving means and from said input signal generation means to differentiate a specified response due to a perturbation from a subsequent specified response due to a subsequent perturbation to determine the chemical or intrinsic physical properties desired.

Metal-silica sol-gel materials

NASA Technical Reports Server (NTRS)

Stiegman, Albert E. (Inventor)

2002-01-01

The present invention relates to a single phase metal-silica sol-gel glass formed by the co-condensation of a transition metal with silicon atoms where the metal atoms are uniformly distributed within the sol-gel glass as individual metal centers. Any transition metal may be used in the sol-gel glasses. The present invention also relates to sensor materials where the sensor material is formed using the single phase metal-silica sol-gel glasses. The sensor materials may be in the form of a thin film or may be attached to an optical fiber. The present invention also relates to a method of sensing chemicals using the chemical sensors by monitoring the chromatic change of the metal-silica sol-gel glass when the chemical binds to the sensor. The present invention also relates to oxidation catalysts where a metal-silica sol-gel glass catalyzes the reaction. The present invention also relates to a method of performing oxidation reactions using the metal-silica sol-gel glasses. The present invention also relates to organopolymer metal-silica sol-gel composites where the pores of the metal-silica sol-gel glasses are filled with an organic polymer polymerized by the sol-gel glass.

Injectable CMC/PEI gel as an in vivo scaffold for demineralized bone matrix.

PubMed

Kim, Kyung Sook; Kang, Yun Mi; Lee, Ju Young; Kim, E Sle; Kim, Chun Ho; Min, Byoung Hyun; Lee, Hai Bang; Kim, Jae Ho; Kim, Moon Suk

2009-01-01

A number of materials have been considered as sources of grafts to repair bone defects. Here, we examined the possibility of creating in situ-forming gels from sodium carboxymethylcellulose (CMC) and poly(ethyleneimine) (PEI) for use as an in vivo carrier of demineralized bone matrix (DBM). The interaction between anionic CMC and cationic PEI was examined by evaluating phase transition behavior and viscosity of CMC solutions containing 0-30 wt% PEI. CMC solutions containing 10 wt% PEI exhibited a sol-to-gel phase transition at temperatures greater than 35 degrees C. The phase transition is caused by electrostatic crosslinking of the CMC/PEI solution to form a gel with a three-dimensional network structure. In situ-formed gel implants were successfully fabricated in vivo by simple subcutaneous injection of the CMC/PEI (90/10) solution (with and without DBM) into Fisher rats. The resulting in situ-formed implant maintained its shape for 28 days in vitro and in vivo. Our results show that in situ-forming CMC/PEI gels can serve as a DBM carrier that can be delivered with a minimally invasive procedure.

Small interfering ribonucleic acid induces liquid-to-ripple phase transformation in a phospholipid membrane

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

Choubey, Amit; Nomura, Ken-ichi; Kalia, Rajiv K.

Small interfering ribonucleic acid (siRNA) molecules play a pivotal role in silencing gene expression via the RNA interference mechanism. A key limitation to the widespread implementation of siRNA therapeutics is the difficulty of delivering siRNA-based drugs to cells. Here, we examine changes in the structure and dynamics of a dipalmitoylphosphatidylcholine bilayer in the presence of a siRNA molecule and mechanical barriers to siRNA transfection in the bilayer. Our all-atom molecular dynamics simulation shows that siRNA induces a liquid crystalline-to-ripple phase transformation in the bilayer. The ripple phase consists of a major region of non-interdigitated and a minor region of interdigitatedmore » lipid molecules with an intervening kink. In the ripple phase, hydrocarbon chains of lipid molecules have large compressive stresses, which present a considerable barrier to siRNA transfection.« less

One pot synthesis of exchange coupled Nd2Fe14B/alpha-Fe by pechini type sol-gel method.

PubMed

Hussain, Abid; Jadhav, Abhijit P; Baek, Yeon Kyung; Choi, Hul Jin; Lee, Jaeho; Kang, Young Soo

2013-11-01

In this work, a combination of nanoparticles of Nd2Fe14B hard magnetic phase and alpha-Fe soft magnetic phase were synthesized by one pot chemical synthesis technique using sol-gel method. A gel of Nd-Fe-B was prepared using NdCl3 x 6H2O, FeCl3 x 6H2O, H3BO3, citric acid, and ethylene glycol by pechini type sol-gel method. The gel was subsequently calcined and annealed to obtain the mixed oxide powders. The produced metal oxide particles were identified with XRD, SEM, TEM to obtain the crystal structure, shape and domain structure of them. The nanoparticles of mixed phase of Nd2Fe14B/alpha-Fe were obtained from these oxides by a process of reduction-diffusion in vacuum by employing CaH2 as reducing agent. During this process it was optimized by controlling temperature, reaction time and concentration of the reducing agent (CaH2). The phase formation of Nd2Fe14B was resulted by the direct diffusion of NdH2, Fe and B. The magnetic property of produced hard and soft phases was successfully identified with vibrating sample magnetometer (VSM). The mixed domains of the hard and soft phases were identified with selected area electron diffraction method (SAED) patterns.

Patterns in shrinking gels

NASA Astrophysics Data System (ADS)

Matsuo, Eriko Sato; Tanaka, Toyoichi

1992-08-01

POLYMER gels can undergo a volume phase transition (either continuous or discontinuous) when an external condition, such as temperature or solvent composition, is altered1-3. During this transition, the volume may change by a factor of several thousand, and various patterns develop in the gel. The patterns arising from swelling and shrinking differ in both their appearance and their physical mechanisms. The mechanism for the formation and evolution of patterns on swelling gels has been established as being due to a single kind of mechanical instability4-7 in contrast, the shrinking patterns seem to be sensitive to both the initial and final states of the transition. Here we classify the various shrinking patterns in the form of a phase diagram, and explain the poly-morphism in terms of macroscopic phase separation.

Influence of Sodium Chloride on the Formation and Dissociation Behavior of CO2 Gas Hydrates.

PubMed

Holzammer, Christine; Schicks, Judith M; Will, Stefan; Braeuer, Andreas S

2017-09-07

We present an experimental study on the formation and dissociation characteristics of carbon dioxide (CO 2 ) gas hydrates using Raman spectroscopy. The CO 2 hydrates were formed from sodium chloride/water solutions with salinities of 0-10 wt %, which were pressurized with liquid CO 2 in a stirred vessel at 6 MPa and a subcooling of 9.5 K. The formation of the CO 2 hydrate resulted in a hydrate gel where the solid hydrate can be considered as the continuous phase that includes small amounts of a dispersed liquid water-rich phase that has not been converted to hydrate. During the hydrate formation process we quantified the fraction of solid hydrate, x H , and the fraction of the dispersed liquid water-rich phase, x L , from the signature of the hydroxyl (OH)-stretching vibration of the hydrate gel. We found that the fraction of hydrate x H contained in the hydrate gel linearly depends on the salinity of the initial liquid water-rich phase. In addition, the ratio of CO 2 and water was analyzed in the liquid water-rich phase before hydrate formation, in the hydrate gel during growth and dissociation, and after its complete dissociation again in the liquid water-rich phase. We observed a supersaturation of CO 2 in the water-rich phase after complete dissociation of the hydrate gel and were able to show that the excess CO 2 exists as dispersed micro- or nanoscale liquid droplets in the liquid water-rich phase. These residual nano- and microdroplets could be a possible explanation for the so-called memory effect.

The Permeability Enhancing Mechanism of DMSO in Ceramide Bilayers Simulated by Molecular Dynamics

PubMed Central

Notman, Rebecca; den Otter, Wouter K.; Noro, Massimo G.; Briels, W. J.; Anwar, Jamshed

2007-01-01

The lipids of the topmost layer of the skin, the stratum corneum, represent the primary barrier to molecules penetrating the skin. One approach to overcoming this barrier for the purpose of delivery of active molecules into or via the skin is to employ chemical permeability enhancers, such as dimethylsulfoxide (DMSO). How these molecules exert their effect at the molecular level is not understood. We have investigated the interaction of DMSO with gel-phase bilayers of ceramide 2, the predominant lipid in the stratum corneum, by means of molecular dynamics simulations. The simulations satisfactorily reproduce the phase behavior and the known structural parameters of ceramide 2 bilayers in water. The effect of DMSO on the gel-phase bilayers was investigated at various concentrations over the range 0.0−0.6 mol fraction DMSO. The DMSO molecules accumulate in the headgroup region and weaken the lateral forces between the ceramides. At high concentrations of DMSO (≥0.4 mol fraction), the ceramide bilayers undergo a phase transition from the gel phase to the liquid crystalline phase. The liquid-crystalline phase of ceramides is expected to be markedly more permeable to solutes than the gel phase. The results are consistent with the experimental evidence that high concentrations of DMSO fluidize the stratum corneum lipids and enhance permeability. PMID:17513383

Advanced porous electrodes with flow channels for vanadium redox flow battery

NASA Astrophysics Data System (ADS)

Bhattarai, Arjun; Wai, Nyunt; Schweiss, Ruediger; Whitehead, Adam; Lim, Tuti M.; Hng, Huey Hoon

2017-02-01

Improving the overall energy efficiency by reducing pumping power and improving flow distribution of electrolyte, is a major challenge for developers of flow batteries. The use of suitable channels can improve flow distribution through the electrodes and reduce flow resistance, hence reducing the energy consumption of the pumps. Although several studies of vanadium redox flow battery have proposed the use of bipolar plates with flow channels, similar to fuel cell designs, this paper presents the use of flow channels in the porous electrode as an alternative approach. Four types of electrodes with channels: rectangular open channel, interdigitated open cut channel, interdigitated circular poked channel and cross poked circular channels, are studied and compared with a conventional electrode without channels. Our study shows that interdigitated open channels can improve the overall energy efficiency up to 2.7% due to improvement in flow distribution and pump power reduction while interdigitated poked channel can improve up to 2.5% due to improvement in flow distribution.

Aeroelastic Analysis of Helicopter Rotor Blades Incorporating Anisotropic Piezoelectric Twist Actuation

NASA Technical Reports Server (NTRS)

Wilkie, W. Keats; Belvin, W. Keith; Park, K. C.

1996-01-01

A simple aeroelastic analysis of a helicopter rotor blade incorporating embedded piezoelectric fiber composite, interdigitated electrode blade twist actuators is described. The analysis consists of a linear torsion and flapwise bending model coupled with a nonlinear ONERA based unsteady aerodynamics model. A modified Galerkin procedure is performed upon the rotor blade partial differential equations of motion to develop a system of ordinary differential equations suitable for dynamics simulation using numerical integration. The twist actuation responses for three conceptual fullscale blade designs with realistic constraints on blade mass are numerically evaluated using the analysis. Numerical results indicate that useful amplitudes of nonresonant elastic twist, on the order of one to two degrees, are achievable under one-g hovering flight conditions for interdigitated electrode poling configurations. Twist actuation for the interdigitated electrode blades is also compared with the twist actuation of a conventionally poled piezoelectric fiber composite blade. Elastic twist produced using the interdigitated electrode actuators was found to be four to five times larger than that obtained with the conventionally poled actuators.

An aeroelastic analysis of helicopter rotor blades incorporating piezoelectric fiber composite twist actuation

NASA Technical Reports Server (NTRS)

Wilkie, W. Keats; Park, K. C.

1996-01-01

A simple aeroelastic analysis of a helicopter rotor blade incorporating embedded piezoelectric fiber composite, interdigitated electrode blade twist actuators is described. The analysis consist of a linear torsion and flapwise bending model coupled with a nonlinear ONERA based unsteady aerodynamics model. A modified Galerkin procedure is performed upon the rotor blade partial differential equations of motion to develop a system of ordinary differential equations suitable for numerical integration. The twist actuation responses for three conceptual full-scale blade designs with realistic constraints on blade mass are numerically evaluated using the analysis. Numerical results indicate that useful amplitudes of nonresonant elastic twist, on the order of one to two degrees, are achievable under one-g hovering flight conditions for interdigitated electrode poling configurations. Twist actuation for the interdigitated electrode blades is also compared with the twist actuation of a conventionally poled piezoelectric fiber composite blade. Elastic twist produced using the interdigitated electrode actuators was found to be four to five times larger than that obtained with the conventionally poled actuators.

Changes in expression of the lysosomal membrane glycoprotein, LAMP-1 in interdigital regions during embryonic mouse limb development, in vivo and in vitro.

PubMed

Stewart, S; Yi, S; Kassabian, G; Mayo, M; Sank, A; Shuler, C

2000-06-01

Syndactyly, a failure of the digits to separate into individual units, affects about 8 to 9 per 1000 newborns and results from an aberration of the normal development of the interdigital tissues. Limb digit separation is the result of programmed cell death (apoptosis). Lysosomes play a role in the process of cell self-destruction. Our experiment was designed to test the hypothesis that the intensity of interdigital lysosomes increases during the separation of digits in vivo and in vitro. The primary mouse monoclonal antibody, 1D4B, detects the presence of lysosomes by identifying the LAMP-1 glycoprotein on the lysosome cell membrane. In our experiment this antibody immunodetected interdigital lysosome proteins in serial sections of limbs from Swiss-Webster mouse embryos, gestational ages E12.5 through E15, key developmental stages for digit separation. Digit separation was associated with an increase in intensity of lysosomal protein staining. In E12.5 limbs, the presence of lysosomes was enriched in the distal aspect of the interdigital tissue. However, the number of lysosomes markedly increased in the E13 and E14 limbs, including the entire length and width of the interdigital tissue in the E14 limbs. This lysosomal protein presence in E14 limbs was significant compared to E12.5, E13, and E15 limbs. By day 12.5, the mouse embryo limb is committed to digit separation. Addition of retinoic acid to the culture medium of limbs earlier in development, such as E12, results in induction of the process of digit separation. Cultured E12 limbs that did not receive an addition of retinoic acid, did not show digit separation. We conclude that in the limb development process, the enrichment in interdigit LAMP-1 proteins, may indicate a relationship between lysosomes, apoptosis, and digit separation. We also conclude that retinoic acid has an important role in digit separation in vivo, as shown in limb development, and demonstrated through the addition of retinoic acid to media of cultured tissues.

Sol-gel open tubular ODS columns with reversed electroosmotic flow for capillary electrochromatography.

PubMed

Hayes, J D; Malik, A

2001-03-01

Sol-gel chemistry was successfully used for the fabrication of open tubular columns with surface-bonded octadecylsilane (ODS) stationary-phase coating for capillary electrochromatography (OT-CEC). Following column preparations, a series of experiments were performed to investigate the performance of the sol-gel coated ODS columns in OT-CEC. The incorporation of N-octadecyldimethyl[3-(trimethoxysilyl)propyl]ammonium chloride as one of the sol-gel precursors played an important role in the electrochromatographic performance of the prepared columns. This chemical reagent possesses a chromatographically favorable, bonded ODS moiety, in conjunction with three methoxy groups allowing for sol-gel reactivity. In addition, a positively charged nitrogen atom is present in the molecular structure of this reagent and provides a positively charged capillary surface responsible for the reversed electroosmotic flow (EOF) in the columns during CEC operation. Comparative studies involving the EOF within such sol-gel ODS coated and uncoated capillaries were performed using acetonitrile and methanol as the organic modifiers in the mobile phase. The use of a deactivating reagent, phenyldimethylsilane, in the sol-gel solution was evaluated. Efficiency values of over 400,000 theoretical plates per meter were achieved in CEC on a 64 cm x 25 microm i.d. sol-gel ODS open tubular column. Test mixtures of polycyclic aromatic hydrocarbons, benzene derivatives, and aromatic aldehydes and ketones were used to evaluate the CEC performances of both nondeactivated and deactivated open tubular sol-gel columns. The effects of mobile-phase organic modifier contents and pH on EOF in such columns were evaluated. The prepared sol-gel ODS columns are characterized by switchable electroosmotic flow. A pH value of approximately 8.5 was found correspond to the isoelectric point for the prepared sol-gel ODS coatings.

Characterization of SrCo1.5Ti1.5Fe9O19 hexagonal ferrite synthesized by sol-gel combustion and solid state route

NASA Astrophysics Data System (ADS)

Vinaykumar, R.; Mazumder, R.; Bera, J.

2017-05-01

Co-Ti co-substituted SrM hexagonal ferrite (SrCo1.5Ti1.5Fe9O19) was synthesized by sol-gel combustion and solid state route. The effects of sources of TiO2 raw materials; titanium tetra-isopropoxide (TTIP) and titanyl nitrate (TN) on the phase formation behavior and properties of the ferrite were studied. The thermal decomposition behavior of the gel was studied using TG-DSC. The phase formation behavior of the ferrite was studied by using X-ray powder diffraction and FTIR analysis. Phase formation was comparatively easier in the TN-based sol-gel process. The morphology of powder and sintered ferrite was investigated using scanning electron microscope. Magnetic properties like magnetization, coercivity, permeability, tan δμ and dielectric properties were investigated. The ferrite synthesized by sol-gel based chemical route showed higher saturation magnetization, permeability and permittivity compared to the ferrite synthesized by solid state route.

Rationalization of reduced penetration of drugs through ceramide gel phase membrane.

PubMed

Paloncýová, Markéta; DeVane, Russell H; Murch, Bruce P; Berka, Karel; Otyepka, Michal

2014-11-25

Since computing resources have advanced enough to allow routine molecular simulation studies of drug molecules interacting with biologically relevant membranes, a considerable amount of work has been carried out with fluid phospholipid systems. However, there is very little work in the literature on drug interactions with gel phase lipids. This poses a significant limitation for understanding permeation through the stratum corneum where the primary pathway is expected to be through a highly ordered lipid matrix. To address this point, we analyzed the interactions of p-aminobenzoic acid (PABA) and its ethyl (benzocaine) and butyl (butamben) esters with two membrane bilayers, which differ in their fluidity at ambient conditions. We considered a dioleoylphosphatidylcholine (DOPC) bilayer in a fluid state and a ceramide 2 (CER2, ceramide NS) bilayer in a gel phase. We carried out unbiased (100 ns long) and biased z-constraint molecular dynamics simulations and calculated the free energy profiles of all molecules along the bilayer normal. The free energy profiles converged significantly slower for the gel phase. While the compounds have comparable affinities for both membranes, they exhibit penetration barriers almost 3 times higher in the gel phase CER2 bilayer. This elevated barrier and slower diffusion in the CER2 bilayer, which are caused by the high ordering of CER2 lipid chains, explain the low permeability of the gel phase membranes. We also compared the free energy profiles from MD simulations with those obtained from COSMOmic. This method provided the same trends in behavior for the guest molecules in both bilayers; however, the penetration barriers calculated by COSMOmic did not differ between membranes. In conclusion, we show how membrane fluid properties affect the interaction of drug-like molecules with membranes.

Exploring the dynamics of phase separation in colloid-polymer mixtures with long range attraction.

PubMed

Sabin, Juan; Bailey, Arthur E; Frisken, Barbara J

2016-06-28

We have studied the kinetics of phase separation and gel formation in a low-dispersity colloid - non-adsorbing polymer system with long range attraction using small-angle light scattering. This system exhibits two-phase and three-phase coexistence of gas, liquid and crystal phases when the strength of attraction is between 2 and 4kBT and gel phases when the strength of attraction is increased. For those samples that undergo macroscopic phase separation, whether to gas-crystal, gas-liquid or gas-liquid-crystal coexistence, we observe dynamic scaling of the structure factor and growth of a characteristic length scale that behaves as expected for phase separation in fluids. In samples that gel, the power law associated with the growth of the dominant length scale is not equal to 1/3, but appears to depend mainly on the strength of attraction, decreasing from 1/3 for samples near the coexistence region to 1/27 at 8kBT, over a wide range of colloid and polymer concentrations.

Poly(amidoamine) dendrimers on lipid bilayers II: Effects of bilayer phase and dendrimer termination.

PubMed

Kelly, Christopher V; Leroueil, Pascale R; Orr, Bradford G; Banaszak Holl, Mark M; Andricioaei, Ioan

2008-08-07

The molecular structures and enthalpy release of poly(amidoamine) (PAMAM) dendrimers binding to 1,2-dimyristoyl- sn-glycero-3-phosphocholine (DMPC) bilayers were explored through atomistic molecular dynamics. Three PAMAM dendrimer terminations were examined: protonated primary amine, neutral acetamide, and deprotonated carboxylic acid. Fluid and gel lipid phases were examined to extract the effects of lipid tail mobility on the binding of generation-3 dendrimers, which are directly relevant to the nanoparticle interactions involving lipid rafts, endocytosis, lipid removal, and/or membrane pores. Upon binding to gel phase lipids, dendrimers remained spherical, had a constant radius of gyration, and approximately one-quarter of the terminal groups were in close proximity to the lipids. In contrast, upon binding to fluid phase bilayers, dendrimers flattened out with a large increase in their asphericity and radii of gyration. Although over twice as many dendrimer-lipid contacts were formed on fluid versus gel phase lipids, the dendrimer-lipid interaction energy was only 20% stronger. The greatest enthalpy release upon binding was between the charged dendrimers and the lipid bilayer. However, the stronger binding to fluid versus gel phase lipids was driven by the hydrophobic interactions between the inner dendrimer and lipid tails.

Highly sensitive three-dimensional interdigitated microelectrode for microparticle detection using electrical impedance spectroscopy

NASA Astrophysics Data System (ADS)

Chang, Fu-Yu; Chen, Ming-Kun; Wang, Min-Haw; Jang, Ling-Sheng

2016-02-01

Cell impedance analysis is widely used for monitoring biological and medical reactions. In this study, a highly sensitive three-dimensional (3D) interdigitated microelectrode (IME) with a high aspect ratio on a polyimide (PI) flexible substrate was fabricated for microparticle detection (e.g. cell quantity detection) using electroforming and lithography technology. 3D finite element simulations were performed to compare the performance of the 3D IME (in terms of sensitivity and signal-to-noise ratio) to that of a planar IME for particles in the sensing area. Various quantities of particles were captured in Dulbecco’s modified Eagle medium and their impedances were measured. With the 3D IME, the particles were arranged in the gap, not on the electrode, avoiding the noise due to particle position. For the maximum particle quantities, the results show that the 3D IME has at least 5-fold higher sensitivity than that of the planar IME. The trends of impedance magnitude and phase due to particle quantity were verified using the equivalent circuit model. The impedance (1269 Ω) of 69 particles was used to estimate the particle quantity (68 particles) with 98.6% accuracy using a parabolic regression curve at 500 kHz.

Influence of the counteranion on the ability of 1-dodecyl-3-methyltriazolium ionic liquids to form mesophases

DOE PAGES

Stappert, Kathrin; Unal, Derya; Spielberg, Eike T.; ...

2014-11-25

The influence of the counteranion on the ability of the mesogenic cation 1-methyl-3-dodecyl-triazolium to form mesophases is explored. To that avail, salts of the cation with anions of different size, shape, and hydrogen bonding capability such as Cl –, Br –, I –, I 3 –, PF 6 –, and Tf 2N – [bis(trifluorosulfonyl)amide] were synthesized and characterized. The crystal structures of the bromide, the iodide, and the triiodide reveal that the cations form bilayers with cations oriented in opposite directions featuring interdigitated alkyl tails. Within the layers, the cations are separated by anions. The rod-shaped triiodide anion forces themore » triazolium cation to align with it in this crystal structure but due to its space requirement reduces the alkyl chain interdigitation which prevents the formation of a mesophase. Rather the compound transforms directly from a crystalline solid to an (ionic) liquid like the analogous bis(trifluorosulfonyl)amide. In contrast, the simple halides and the hexafluorophosphate form liquid crystalline phases. As a result, their clearing points shift with increasing anion radius to lower temperatures.« less

Energy storage crystalline gel materials for 3D printing application

NASA Astrophysics Data System (ADS)

Mao, Yuchen; Miyazaki, Takuya; Gong, Jin; Zhu, Meifang

2017-04-01

Phase change materials (PCMs) are considered one of the most reliable latent heat storage and thermoregulation materials. In this paper, a vinyl monomer is used to provide energy storage capacity and synthesize gel with phase change property. The side chain of copolymer form crystal microcell to storage/release energy through phase change. The crosslinking structure of the copolymer can protect the crystalline micro-area maintaining the phase change stable in service and improving the mechanical strength. By selecting different monomers and adjusting their ratios, we design the chemical structure and the crystallinity of gels, which in further affect their properties, such as strength, flexibility, thermal absorb/release transition temperature, transparency and the water content. Using the light-induced polymerization 3D printing techniques, we synthesize the energy storage gel and shape it on a 3D printer at the same time. By optimizing the 3D printing conditions, including layer thickness, curing time and light source, etc., the 3D printing objects are obtained.

Microwave characteristics of interdigitated photoconductors on a HEMT structure. M.S. Thesis. Final Contractor Report

NASA Technical Reports Server (NTRS)

Hill, Scott M.; Claspy, Paul C.

1988-01-01

Interdigitated photoconductive detectors of various geometries were fabricated on AlGaAs/GaAs heterostructure material. The processes used in the fabrication of these devices are described, and the results of a study of their optical and electrical characteristics are presented.

Solid-phase assays for small molecule screening using sol-gel entrapped proteins.

PubMed

Lebert, Julie M; Forsberg, Erica M; Brennan, John D

2008-04-01

With compound libraries exceeding one million compounds, the ability to quickly and effectively screen these compounds against relevant pharmaceutical targets has become crucial. Solid-phase assays present several advantages over solution-based methods. For example, a higher degree of miniaturization can be achieved, functional- and affinity-based studies are possible, and a variety of detection methods can be used. Unfortunately, most protein immobilization methods are either too harsh or require recombinant proteins and thus are not amenable to delicate proteins such as kinases and membrane-bound receptors. Sol-gel encapsulation of proteins in an inorganic silica matrix has emerged as a novel solid-phase assay platform. In this minireview, we discuss the development of sol-gel derived protein microarrays and sol-gel based monolithic bioaffinity columns for the high-throughput screening of small molecule libraries and mixtures.

Crystalline-gel-molten phase transitions of water in calcium dipicolinate (Ca-DPA)

NASA Astrophysics Data System (ADS)

Tiwari, Subodh; Mishra, Ankit; Sheng, Chunyang; Rajak, Pankaj; Kalia, Rajiv; Nakano, Aiichiro; Vashishta, Priya

The heat resistance of bacterial spores directly correlates to the protoplast dehydration and presence of dipicolinic acid (DPA) and its associated metal salts at the core. Bacteria's structural integrity in moist heat conferred by high concentration of DPA and calcium DPA salts depends on the properties are additional water molecules and temperature. In our reactive MD simulations, we characterize different possible phases and the transport properties of water molecules. We observed solid-gel and gel-liquid phase transitions of the hydrated Ca-DPA system. These simulations reveal monotonically decreasing solid-gel-liquid transition temperatures with increasing cell hydration, reflecting the experimental trend of moist-heat resistance of bacterial spores. We also observed that the calcification of bacterial spores further increases the transition temperatures. This research is supported by DTRA Grant No. HDTRA1-14-1-0074.

Detection of radio-frequency modulated optical signals by two and three terminal microwave devices

NASA Technical Reports Server (NTRS)

Bhasin, K. B.; Simons, R. N.; Wojtczuk, S.

1987-01-01

An interdigitated photoconductor (two terminal device) on GaAlAs/GaAs heterostructure was fabricated and tested by an electro-optical sampling technique. Further, the photoresponse of GaAlAs/GaAs HEMT (three terminal device) was obtained by illuminating the device with an optical signal modulated up to 8 GHz. Gain-bandwidth product, response time, and noise properties of photoconductor and HEMT devices were obtained. Monolithic integration of these photodetectors with GaAs microwave devices for optically controlled phased array antenna applications is discussed.

Chemomechanical synchronization in heterogeneous self-oscillating gels

NASA Astrophysics Data System (ADS)

Yashin, Victor V.; Balazs, Anna C.

2008-04-01

Using computational modeling, we introduce patches of self-oscillating gels undergoing the Belousov-Zhabotinsky (BZ) reaction into a nonreactive polymer network and thereby demonstrate how these BZ gels can be harnessed to impart remarkable functionality to the entire system. By first focusing on two adjacent patches of BZ gels, we show that the patches’ oscillations can become synchronized in phase or out of phase, with the oscillation frequency depending on the synchronization mode and the spatial separation between these domains. We then apply these results to an array of five adjacent BZ patches and by varying the distance between these pieces, we dramatically alter the dynamical behavior of the patterned gel. For example, the sample can be made to exhibit a unidirectional traveling wave or display a concerted expansion and contraction, properties that are valuable for creating gel-based devices, such as micropumps and microactuators. The findings point to a “modular” design approach, which can impart different functionality simply by arranging identical pieces of BZ gels into distinct spatial arrangements within a polymer matrix.

Piezoelectric microgenerators--current status and challenges.

PubMed

Kim, Hyun-Uk; Lee, Woo-Ho; Dias, H V Rasika; Priya, Shashank

2009-08-01

This manuscript reviews the developments made in design and fabrication of piezoelectric microgenerators and presents a method for making a comparative study within various vibration energy harvesting mechanisms. Current generation vibration energy harvesters have power density in the range of 0.8 microW/mm3. The manuscript also reports our results on synthesis of barium titanate (BT) thin films for MEMS (micro-electromechanical systems) based energy harvester. BT sol-gel was synthesized by aqueous process using barium acetate and titanium bis (ammonium lacto) dihydroxide with PVP (Polyvinylpyrrolidone). After optimizing the annealing temperature and time, textured BT films with 600 nm thickness were obtained on (111) Pt/Ti/SiO2 wafer. A MEMS fabrication process flow was designed to produce microcantilever chips from BT films constituting 6 cantilevers connected in series with an interdigital electrode pattern. We also present some concepts for further improvement of the power density of vibration energy harvesters by incorporating 3-D structure, magnetoelectric material, and a multimodal scheme.

Changes in the myosin secondary structure and shrimp surimi gel strength induced by dense phase carbon dioxide.

PubMed

Guo, Minghui; Liu, Shucheng; Ismail, Marliya; Farid, Mohammed M; Ji, Hongwu; Mao, Weijie; Gao, Jing; Li, Chengyong

2017-07-15

Dense phase carbon dioxide (DPCD) could induce protein conformation changes. Myosin and shrimp surimi from Litopenaeus vannamei were treated with DPCD at 5-25MPa and 40-60°C for 20min. Myosin secondary structure was investigated by circular dichroism and shrimp surimi gel strength was determined using textural analysis to develop correlations between them. DPCD had a greater effect on secondary structure and gel strength than heating. With increasing pressure and temperature, the α-helix content of DPCD-treated myosin decreased, while the β-sheet, β-turn and random coil contents increased, and the shrimp surimi gel strength increased. The α-helix content was negatively correlated with gel strength, while the β-sheet, β-turn and random coil contents were positively correlated with gel strength. Therefore, when DPCD induced myosin to form a gel, the α-helix of myosin was unfolded and gradually converted to a β-sheet. Such transformations led to protein-protein interactions and cross-linking, which formed a three-dimensional network to enhance the gel strength. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of Sodium Chloride on the Formation and Dissociation Behavior of CO2 Gas Hydrates

PubMed Central

2017-01-01

We present an experimental study on the formation and dissociation characteristics of carbon dioxide (CO2) gas hydrates using Raman spectroscopy. The CO2 hydrates were formed from sodium chloride/water solutions with salinities of 0–10 wt %, which were pressurized with liquid CO2 in a stirred vessel at 6 MPa and a subcooling of 9.5 K. The formation of the CO2 hydrate resulted in a hydrate gel where the solid hydrate can be considered as the continuous phase that includes small amounts of a dispersed liquid water-rich phase that has not been converted to hydrate. During the hydrate formation process we quantified the fraction of solid hydrate, xH, and the fraction of the dispersed liquid water-rich phase, xL, from the signature of the hydroxyl (OH)-stretching vibration of the hydrate gel. We found that the fraction of hydrate xH contained in the hydrate gel linearly depends on the salinity of the initial liquid water-rich phase. In addition, the ratio of CO2 and water was analyzed in the liquid water-rich phase before hydrate formation, in the hydrate gel during growth and dissociation, and after its complete dissociation again in the liquid water-rich phase. We observed a supersaturation of CO2 in the water-rich phase after complete dissociation of the hydrate gel and were able to show that the excess CO2 exists as dispersed micro- or nanoscale liquid droplets in the liquid water-rich phase. These residual nano- and microdroplets could be a possible explanation for the so-called memory effect. PMID:28817275

Phenomenological model and phase behavior of saturated and unsaturated lipids and cholesterol.

PubMed

Putzel, G Garbès; Schick, M

2008-11-15

We present a phenomenological theory for the phase behavior of ternary mixtures of cholesterol and saturated and unsaturated lipids, one that describes both liquid and gel phases. It leads to the following description of the mechanism of the phase behavior: In a binary system of the lipids, phase separation occurs when the saturated chains are well ordered, as in the gel phase, simply due to packing effects. In the liquid phase, the saturated ones are not sufficiently well ordered for separation to occur. The addition of cholesterol, however, increases the saturated lipid order to the point that phase separation is once again favorable. Our theory addresses this last mechanism-the means by which cholesterol-mediated ordering of membrane lipids leads to liquid-liquid immiscibility. It produces, for the system above the main chain transition of the saturated lipid, phase diagrams in which there can be liquid-liquid phase separation in the ternary system but not in any of the binary ones, while below that temperature it yields the more common phase diagram in which a gel phase, rich in saturated lipid, appears in addition to the two liquid phases.

Ignition and combustion characteristics of metallized propellants, phase 2

NASA Technical Reports Server (NTRS)

Mueller, D. C.; Turns, S. R.

1994-01-01

Experimental and analytical investigations focusing on aluminum/hydrocarbon gel droplet secondary atomization and its effects on gel-fueled rocket engine performance are being conducted. A single laser sheet sizing/velocimetry diagnostic technique, which should eliminate sizing bias in the data collection process, has been designed and constructed to overcome limitations of the two-color forward-scatter technique used in previous work. Calibration of this system is in progress and the data acquisition/validation code is being written. Narrow-band measurements of radiant emission, discussed in previous reports, will be used to determine if aluminum ignition has occurred in a gel droplet. A one-dimensional model of a gel-fueled rocket combustion chamber, described in earlier reports, has been exercised in conjunction with a two-dimensional, two-phase nozzle code to predict the performance of an aluminum/hydrocarbon fueled engine. Estimated secondary atomization effects on propellant burnout distance, condensed particle radiation losses to the chamber walls, and nozzle two phase flow losses are also investigated. Calculations indicate that only modest secondary atomization is required to significantly reduce propellant burnout distances, aluminum oxide residual size, and radiation heat losses. Radiation losses equal to approximately 2-13 percent of the energy released during combustion were estimated, depending on secondary atomization intensity. A two-dimensional, two-phase nozzle code was employed to estimate radiation and nozzle two phase flow effects on overall engine performance. Radiation losses yielded a one percent decrease in engine Isp. Results also indicate that secondary atomization may have less effect on two-phase losses than it does on propellant burnout distance and no effect if oxide particle coagulation and shear induced droplet breakup govern oxide particle size. Engine Isp was found to decrease from 337.4 to 293.7 seconds as gel aluminum mass loading was varied from 0-70 wt percent. Engine Isp efficiencies, accounting for radiation and two phase flow effects, on the order of 0.946 were calculated for a 60 wt percent gel, assuming a fragmentation ratio of five.

Investigation of phase evolution of CaCu3Ti4O12 (CCTO) by in situ synchrotron high-temperature powder diffraction

NASA Astrophysics Data System (ADS)

Ouyang, Xin; Huang, Saifang; Zhang, Weijun; Cao, Peng; Huang, Zhaohui; Gao, Wei

2014-03-01

In situ synchrotron X-ray powder diffraction was used to study the high-temperature phase evolution of CaCu3Ti4O12 (CCTO) precursors prepared via solid-state and sol-gel methods. After the precursors are heated to 1225 °C, the CCTO phase is the main phase observed in the calcined powder, with the presence of some minor impurities. Comparing the two precursors, we found that the onset temperature for the CCTO phase formation is 800 °C in the sol-gel precursor, lower than that in the solid-state precursor (875 °C). Intermediate phases were only observed in the sol-gel precursor. Both precursors are able to be calcined to sub-micrometric sized powders. Based on the synchrotron data along with differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA), the phase formation sequence and mechanism during calcination are proposed in this study.

Bacterial RNA isolation.

PubMed

Ares, Manuel

2012-09-01

In this bacterial RNA isolation protocol, an "RNA-protective" treatment is followed by lysozyme digestion of the peptidoglycan component of the cell wall. EDTA promotes the loss of the outer membrane of Gram-negative bacteria and allows the lysozyme better access to the peptidoglycan. Cells begin to lyse during digestion in hypotonic lysozyme buffer and lysis is completed by sodium dodecyl sulfate (SDS) and hot phenol:chloroform:isoamyl alcohol (PCA) extraction. SDS and hot phenol disrupt membranes, denature protein (including RNase), and strip proteins from RNA. The separation of the organic phase from the aqueous phase is achieved using Phase Lock Gel, an inert material with a density intermediate between the organic and aqueous samples. The sample is split into three phases: from bottom to top, these are phenol and chloroform (organic phase), the inert gel with the interface material, and the aqueous phase with the RNA. The gel acts as a physical barrier between the sample and the organic phase plus interface. Following organic extraction, the RNA is concentrated by ethanol precipitation.

Interdigitating cells in the thymus of the frog, Rana temporaria.

PubMed

Bigaj, J; Płytycz, B

1987-01-01

Interdigitating cells (IDC) of the thymic medulla of the frog, Rana temporaria, collected in the summer, were examined by electron microscopy. The most characteristic cytological features of IDC are voluminous electron-lucent cytoplasm and widespread interdigitations and invaginations of the cell membrane. IDC possess an excentrically located nucleus with pronounced nucleoli and a thin rim of a dense chromatine as well as a perinuclear area with characteristic tubulo-vesicular complex. In our material Birbeck granules were absent. Some IDC contain phagocytized material. A few transitional forms between monocytes and IDC were observed. On the basis of these observations it is highly probable that the amphibian IDC belong to the mononuclear phagocyte system.

A wideband superconducting filter at Ku-band based on interdigital coupling

NASA Astrophysics Data System (ADS)

Jiang, Ying; Wei, Bin; Cao, Bisong; Li, Qirong; Guo, Xubo; Jiang, Linan; Song, Xiaoke; Wang, Xiang

2018-04-01

In this paper, an interdigital-type resonator with strong electric coupling is proposed for the wideband high-frequency (>10 GHz) filter design. The proposed microstrip resonator consists of an H-shaped main line part with its both ends installed with interdigital finger parts. Strong electric coupling is achieved between adjacent resonators. A six-pole high-temperature superconducting filter at Ku-band using this resonator is designed and fabricated. The filter has a center frequency of 15.11 GHz with a fractional bandwidth of 30%. The insertion loss of the passband is less than 0.3 dB, and the return loss is greater than 14 dB without any tuning.

Dermatoglyphs in carriers of a balanced 15;21 translocation.

PubMed

Rodewald, A; Zankl, M; Zankl, H; Zang, K D

1980-08-01

Cytogenetic and dermatoglyphic features were studied in a large family with an inherited 15;21 translocation. Of 35 healthy members of the family, 21 carried the translocation chromosome and 14 were chromosomally normal. There were six members with Down's syndrome who had the translocation. Dermatoglyphic studies showed that carriers of this balanced translocation had the following peculiarities significantly more often than the general population. On the hands, they had ulnar loops on the fingertips, symmetrical high terminations of the A line, symmetrical ulnar loops on the hypothenar areas, distal loops in the 3rd interdigital areas, open fields in the 4th interdigital areas, axial triradii in the distal position, and single transverse palmar creases (Sydney lines). On the feet, they had small distal loops on the hallucal area and distal loops in the 4th interdigital areas. The translocation carriers also had significantly more often than non-carrier relatives symmetrical high terminations of the A line, open fields in the 4th interdigital areas, distal axial triradii, and Sydney lines. On the feet, they had small distal loops on the hallucal areas, distal loops in the 4th interdigital areas, and tibial loops on the proximal hypothenar areas. The data obtained from this study, and especially the values of the Walker and general indices, indicate that some of the dermatoglyphic stigmata of Down's syndrome are directly associated with the 15;21 translocation carrier state and can therefore be used for predicting that state.

Exogenous Cellulase Switches Cell Interdigitation to Cell Elongation in an RIC1-dependent Manner in Arabidopsis thaliana Cotyledon Pavement Cells.

PubMed

Higaki, Takumi; Takigawa-Imamura, Hisako; Akita, Kae; Kutsuna, Natsumaro; Kobayashi, Ryo; Hasezawa, Seiichiro; Miura, Takashi

2017-01-01

Pavement cells in cotyledons and true leaves exhibit a jigsaw puzzle-like morphology in most dicotyledonous plants. Among the molecular mechanisms mediating cell morphogenesis, two antagonistic Rho-like GTPases regulate local cell outgrowth via cytoskeletal rearrangements. Analyses of several cell wall-related mutants suggest the importance of cell wall mechanics in the formation of interdigitated patterns. However, how these factors are integrated is unknown. In this study, we observed that the application of exogenous cellulase to hydroponically grown Arabidopsis thaliana cotyledons switched the interdigitation of pavement cells to the production of smoothly elongated cells. The cellulase-induced inhibition of cell interdigitation was not observed in a RIC1 knockout mutant. This gene encodes a Rho-like GTPase-interacting protein important for localized cell growth suppression via microtubule bundling on concave cell interfaces. Additionally, to characterize pavement cell morphologies, we developed a mathematical model that considers the balance between cell and cell wall growth, restricted global cell growth orientation, and regulation of local cell outgrowth mediated by a Rho-like GTPase-cytoskeleton system. Our computational simulations fully support our experimental observations, and suggest that interdigitated patterns form because of mechanical buckling in the absence of Rho-like GTPase-dependent regulation of local cell outgrowth. Our model clarifies the cell wall mechanics influencing pavement cell morphogenesis. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Synthesis of Self-Bonded Pellets of ETS-4 Phase by New Methodology of Preparation

NASA Astrophysics Data System (ADS)

De Luca, P.; Mastroianni, C.; Nagy, J. B.

2018-06-01

We hereby present the results of a research in order to prepare self-bonded pellets of ETS-4 phase by a new methodology of preparation. In particular, the pellets were prepared by kneading crystals of ETS-4 phase and a dry gel, the latter being the precursor for the synthesis of the ETS-4 phase crystals. One of the innovative aspects that is proposed and highlighted in this work is represented by the fact that the dry-gel acts as a “binder”. It is characterized by the same chemical composition of crystals, thus avoiding contamination with other elements. In addition, dry-gel allows, the promotion of nucleation phenomena and thus the formation of new crystals of ETS-4 during the pellets baking phases. The pellets were characterized by X-ray diffraction (XRD), Electron microscopy (SEM) and mechanical strength by hardness tester.

Physically incorporated extraction phase of solid-phase microextraction by sol-gel technology.

PubMed

Liu, Wenmin; Hu, Yuan; Zhao, Jinghong; Xu, Yuan; Guan, Yafeng

2006-01-13

A sol-gel method for the preparation of solid-phase microextraction (SPME) fiber was described and evaluated. The extraction phase of poly(dimethysiloxane) (PDMS) containing 3% vinyl group was physically incorporated into the sol-gel network without chemical bonding. The extraction phase itself is then partly crosslinked at 320 degrees C, forming an independent polymer network and can withstand desorption temperature of 290 degrees C. The headspace extraction of BTX by the fiber SPME was evaluated and the detection limit of o-xylene was down to 0.26 ng/l. Extraction and determination of organophosphorus pesticides (OPPs) in water, orange juice and red wine by the SPME-GC thermionic specified detector (TSD) was validated. Limits of detection of the method for OPPs were below 10 ng/l except methidathion. Relative standard deviations (RSDs) were in the range of 1-20% for pesticides being tested.

Using colloidal silica as isolator, diverter and blocking agent for subsurface geological applications

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

Bourcier, William L.; Roberts, Sarah K.; Roberts, Jeffery J.

A system for blocking fast flow paths in geological formations includes preparing a solution of colloidal silica having a nonviscous phase and a solid gel phase. The solution of colloidal silica is injected into the geological formations while the solution of colloidal silica is in the nonviscous phase. The solution of colloidal silica is directed into the fast flow paths and reaches the solid gel phase in the fast flow paths thereby blocking flow of fluid in the fast paths.

Effects of a wax organogel and alginate gel complex on holy basil (Ocimum sanctum) in vitro ruminal dry matter disappearance and gas production.

PubMed

Templeman, James R; Rogers, Michael A; Cant, John P; McBride, Brian W; Osborne, Vern R

2018-02-20

The objectives of this study were to: (a) select an ideal organogel for the oil phase of a novel gel encapsulation technology, (b) optimize the formulation of an organogel and sodium alginate-based gel complex, and (c) examine the rumen protective ability of the gel by measuring 48-h in vitro ruminal dry matter disappearance and gas production from encapsulated dried and ground holy basil leaves. A rice-bran wax and canola oil organogel was selected for the oil phase of the gel complex as this combination had a 48-h dry matter disappearance of 6%, the lowest of all organogels analyzed. The gel complex was formulated by homogenizing the organogel with a sodium alginate solution to create a low-viscosity oil-in-water emulsion. Average dry matter disappearance of gel-encapsulated holy basil was 19%, compared to 42% for the free, unprotected holy basil. However, gel encapsulation of holy basil stimulated gas production. Specifically, gas production of encapsulated holy basil was four times higher than the treatment with holy basil added on top of the gel prior to incubation rather than encapsulated within the gel. Although the gel itself was highly degradable, it is speculated encapsulation thwarted holy basil's antimicrobial activity. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

Monte Carlo Modeling of VLWIR HgCdTe Interdigitated Pixel Response

NASA Astrophysics Data System (ADS)

D'Souza, A. I.; Stapelbroek, M. G.; Wijewarnasuriya, P. S.

2010-07-01

Increasing very long-wave infrared (VLWIR, λ c ≈ 15 μm) pixel operability was approached by subdividing each pixel into four interdigitated subpixels. High response is maintained across the pixel, even if one or two interdigitated subpixels are deselected (turned off), because interdigitation provides that the preponderance of minority carriers photogenerated in the pixel are collected by the selected subpixels. Monte Carlo modeling of the photoresponse of the interdigitated subpixel simulates minority-carrier diffusion from carrier creation to recombination. Each carrier generated at an appropriately weighted random location is assigned an exponentially distributed random lifetime τ i, where < τ i> is the bulk minority-carrier lifetime. The minority carrier is allowed to diffuse for a short time d τ, and the fate of the carrier is decided from its present position and the boundary conditions, i.e., whether the carrier is absorbed in a junction, recombined at a surface, reflected from a surface, or recombined in the bulk because it lived for its designated lifetime. If nothing happens, the process is then repeated until one of the boundary conditions is attained. The next step is to go on to the next carrier and repeat the procedure for all the launches of minority carriers. For each minority carrier launched, the original location and boundary condition at fatality are recorded. An example of the results from Monte Carlo modeling is that, for a 20- μm diffusion length, the calculated quantum efficiency (QE) changed from 85% with no subpixels deselected, to 78% with one subpixel deselected, 67% with two subpixels deselected, and 48% with three subpixels deselected. Demonstration of the interdigitated pixel concept and verification of the Monte Carlo modeling utilized λ c(60 K) ≈ 15 μm HgCdTe pixels in a 96 × 96 array format. The measured collection efficiency for one, two, and three subelements selected, divided by the collection efficiency for all four subelements selected, matched that calculated using Monte Carlo modeling.

Evaluation of a new charge algorithm for a lead-acid battery with gelled electrolyte using a 96V gel cell IV as a test battery

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

Nowak, D.K.

1989-10-01

This document has reported a summary of test results obtained utilizing the new UAH charge algorithm for Lead-Acid batteries with gelled electrolyte. The battery performance data for a 96V Phase IV Gel/Cell battery pack was tested in a Jet Industries Electrica vehicle. It was shown that the new charge concept is sound although there can be problems with batteries that are highly imbalanced and where excessive electronic noise is experienced on the electronic signal feed-back line that carries the voltage sensor signals from the battery. Additional work is needed to add intelligence to the charge algorithm in terms of amore » better ability to extract the beginning of gas development from the voltage spread function. This can probably be accomplished by scanning the voltages more often and including that data into the function analysis by adding software filters. The Phase IV Gel/Cell battery performance was found to be about 20% lower than that of the Phase III Gel/Cell battery. Problems with cell valve leakage were encountered in the Phase IV Gel/Cell that pose a threat to battery life although so far no battery module has been lost. 2 refs., 13 figs., 4 tabs.« less

Experimental Studies of Adhesion of a Highly Swollen Gel

NASA Astrophysics Data System (ADS)

Cole, Phillip; Emerson, John

2003-03-01

A fracture mechanics methodology based on the Johnson-Kendall-Roberts (JKR) theory is used to quantify the self-adhesion of a highly swollen gel. The solid phase of the gel is a cross-linked polybutadiene and the liquid phase is dibutylphthlate (maximum 60% by weight). In these experiments two nearly identical gel lenses are brought into contact. Bonding and separation of contact is analyzed in terms of the modified JKR theory of Shull [1]. Simultaneous measurements of the applied load, the load point displacement and the contact radius between the lenses allow us to determine the elastic modulus of the gel and the energy release rate. It also allows us to determine whether the observed hysteresis is primarily due to surface dissipation or due to bulk viscoelasticity. The energy release rate is found to be approximately constant during the bonding phase of the experiment. During the debonding phase, the energy release rate increases with the crack velocity or the receding rate of contact radius. Self-adhesion is quantified in the debonding phase through the relationship between the energy release rate and the crack growth rate. The energy release rate during the bonding phase is compared to the surface tension of the liquid and the solid. We also study the effect of liquid phase on the self-adhesion by varying the amount of liquid from zero percent to the maximum of sixty percent. [1] Shull, K. R. Materials Science and Engineering R-Reports, 36 (2002) 1-45. This work was performed at Sandia National Laboratories, supported by the United States Department of Energy under contract number DE-AC04-94AL85000.

Preparation of long alumina fibers by sol-gel method using tartaric acid

NASA Astrophysics Data System (ADS)

Tan, Hong-Bin

2011-12-01

Long alumina fibers were prepared by sol-gel method. The spinning sol was obtained by mixing aluminum nitrate, tartaric acid, and polyvinylpyrrolidone with a mass ratio of 10:3:1.5. Thermogravimetry-differential scanning calorimetry (TG-DSC), Fourier transform infrared (FT-IR) spectra, X-ray diffraction (XRD), and scanning electron microscopy (SEM) were used to characterize the properties of the gel and ceramic fibers. A little of α-Al2O3 phase is observed in the alumina precursor gel fibers sintered at 1273 K. The fibers with a uniform diameter can be obtained when sintered at 1473 K, and its main phase is also indentified as α-Al2O3.

Mayenite Synthesized Using the Citrate Sol-Gel Method

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

Ude, Sabina N; Rawn, Claudia J; Meisner, Roberta A

2014-01-01

A citrate sol-gel method has been used to synthesize mayenite (Ca12Al14O33). X-ray powder diffraction data show that the samples synthesized using the citrate sol-gel method contained CaAl2O4 and CaCO3 along with mayenite when fired ex-situ in air at 800 C but were single phase when fired at 900 C and above. Using high temperature x-ray diffraction, data collected in-situ in air at temperatures of 600 C and below showed only amorphous content; however, data collected at higher temperatures indicated the first phase to crystallize is CaCO3. High temperature x-ray diffraction data collected in 4% H2/96% N2 does not show themore » presence of CaCO3, and Ca12Al14O33 starts to form around 850 C. In comparison, x-ray powder diffraction data collected ex-situ on samples synthesized using traditional solid-state synthesis shows that single phase was not reached until samples were fired at 1350 C. DTA/TGA data collected either in a nitrogen environment or air on samples synthesized using the citrate gel method suggest the complete decomposition of metastable phases and the formation of mayenite at 900 C, although the phase evolution is very different depending on the environment. Brunauer-Emmett-Teller (BET) measurements showed a slightly higher surface area of 7.4 0.1 m2/g in the citrate gel synthesized samples compared to solid-state synthesized sample with a surface area of 1.61 0.02 m2/g. SEM images show a larger particle size for samples synthesized using the solid-state method compared to those synthesized using the citrate gel method.« less

Pharmacokinetic evaluation of novel midazolam gel formulations following buccal administration to healthy dogs.

PubMed

Aldawsari, Mohammed F; Lau, Vivian W; Babu, Ramapuram J; Arnold, Robert D; Platt, Simon R

2018-01-01

OBJECTIVE To determine the physiochemical properties and pharmacokinetics of 3 midazolam gel formulations following buccal administration to dogs. ANIMALS 5 healthy adult hounds. PROCEDURES In phase 1 of a 2-phase study, 2 gel formulations were developed that contained 1% midazolam in a poloxamer 407 (P1) or hydroxypropyl methylcellulose (H1) base and underwent rheological and in vitro release analyses. Each formulation was buccally administered to 5 dogs such that 0.3 mg of midazolam/kg was delivered. Each dog also received midazolam hydrochloride (0.3 mg/kg, IV). There was a 3-day interval between treatments. Blood samples were collected immediately before and at predetermined times for 8 hours after drug administration for determination of plasma midazolam concentration and pharmacokinetic analysis. During phase 2, a gel containing 2% midazolam in a hydroxypropyl methylcellulose base (H2) was developed on the basis of phase 1 results. That gel was buccally administered such that midazolam doses of 0.3 and 0.6 mg/kg were delivered. Each dog also received midazolam (0.3 mg/kg, IV). All posttreatment procedures were the same as those for phase 1. RESULTS The H1 and H2 formulations had lower viscosity, greater bioavailability, and peak plasma midazolam concentrations that were approximately 2-fold as high, compared with those for the P1 formulation. The mean peak plasma midazolam concentration for the H2 formulation was 187.0 and 106.3 ng/mL when the midazolam dose administered was 0.6 and 0.3 mg/kg, respectively. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that buccal administration of gel formulations might be a viable alternative for midazolam administration to dogs.

A review on development of solid phase microextraction fibers by sol-gel methods and their applications.

PubMed

Kumar, Ashwini; Gaurav; Malik, Ashok Kumar; Tewary, Dhananjay Kumar; Singh, Baldev

2008-03-03

Solid phase microextraction (SPME) is an innovative, solvent free technology that is fast, economical and versatile. SPME is a fiber coated with a liquid (polymer), a solid (sorbent) or a combination of both. The fiber coating takes up the compounds from the sample by absorption in the case of liquid coatings or adsorption in the case of solid coatings. The SPME fiber is then transferred with the help of a syringe like device into the analytical instrument for desorption and analysis of the target analytes. The sol-gel process provides a versatile method to prepare size, shape and charge selective materials of high purity and homogeneity by means of preparation techniques different from the traditional ones, for the chemical analysis. This review is on the current state of the art and future trends in the developments of solid phase microextraction (SPME) fibers using sol-gel method. To achieve more selective determination of different compound classes, the variety of different coating material for SPME fibers has increased. Further developments in SPME as a highly efficient extraction technique, will greatly depend on new breakthroughs in the area of new coating material developments for the SPME fibers. In sol-gel approach, appropriate sol-gel precursors and other building blocks can be selected to create a stationary phase with desired structural and surface properties. This approach is efficient in integrating the advantageous properties of organic and inorganic material systems and thereby increasing and improving the extraction selectivity of the produced amalgam organic-inorganic stationary phases. This review is mainly focused on recent advanced developments in the design, synthesis, characterisation, properties and application of sol-gel in preparation of coatings for the SPME fibers.

Analysis of Lipid Phase Behavior and Protein Conformational Changes in Nanolipoprotein Particles upon Entrapment in Sol–Gel-Derived Silica

PubMed Central

2015-01-01

The entrapment of nanolipoprotein particles (NLPs) and liposomes in transparent, nanoporous silica gel derived from the precursor tetramethylorthosilicate was investigated. NLPs are discoidal patches of lipid bilayer that are belted by amphiphilic scaffold proteins and have an average thickness of 5 nm. The NLPs in this work had a diameter of roughly 15 nm and utilized membrane scaffold protein (MSP), a genetically altered variant of apolipoprotein A-I. Liposomes have previously been examined inside of silica sol–gels and have been shown to exhibit instability. This is attributed to their size (∼150 nm) and altered structure and constrained lipid dynamics upon entrapment within the nanometer-scale pores (5–50 nm) of the silica gel. By contrast, the dimensional match of NLPs with the intrinsic pore sizes of silica gel opens the possibility for their entrapment without disruption. Here we demonstrate that NLPs are more compatible with the nanometer-scale size of the porous environment by analysis of lipid phase behavior via fluorescence anisotropy and analysis of scaffold protein secondary structure via circular dichroism spectroscopy. Our results showed that the lipid phase behavior of NLPs entrapped inside of silica gel display closer resemblance to its solution behavior, more so than liposomes, and that the MSP in the NLPs maintain the high degree of α-helix secondary structure associated with functional protein–lipid interactions after entrapment. We also examined the effects of residual methanol on lipid phase behavior and the size of NLPs and found that it exerts different influences in solution and in silica gel; unlike in free solution, silica entrapment may be inhibiting NLP size increase and/or aggregation. These findings set precedence for a bioinorganic hybrid nanomaterial that could incorporate functional integral membrane proteins. PMID:25062385

Crystalline smectic E phase revisited in case of symmetrical dibenzo-18-crown-6-ether azomethine dimers

NASA Astrophysics Data System (ADS)

Cozan, Vasile; Ardeleanu, Rodinel; Airinei, Anton; Timpu, Daniel

2018-03-01

Three symmetric azomethine dimers having dibenzo-18-crown-6-ether as internal moiety and halogens (F, Cl, Br) as terminal functional groups were synthesized and characterized by FTIR and 1H NMR spectroscopy. Their thermal behavior was investigated by polarized optical microscopy (POM) and DSC techniques. Interesting textures have been observed at cooling by POM as being representative for a soft crystalline smectic phase. X-ray diffraction measurements in powder at room temperature exhibited a map of reflections corresponding to crystal E phase. The influence of molecular parameters (interdigitation parameter γ, dipole moment, molecular polarizability, halogen radius) on thermal behavior was discussed. The UV-Vis investigations allowed evaluation of photostability and a bathochromic effect was noticed with the increasing of halogen atom radius. Also the values of optical band gap (Eg) are higher than those corresponding to conjugated Schiff bases.

Investigations on KONUS beam dynamics using the pre-stripper drift tube linac at GSI

NASA Astrophysics Data System (ADS)

Xiao, C.; Du, X. N.; Groening, L.

2018-04-01

Interdigital H-mode (IH) drift tube linacs (DTLs) based on KONUS beam dynamics are very sensitive to the rf-phases and voltages at the gaps between tubes. In order to design these DTLs, a deep understanding of the underlying longitudinal beam dynamics is mandatory. The report presents tracking simulations along an IH-DTL using the PARTRAN and BEAMPATH codes together with MATHCAD and CST. Simulation results illustrate that the beam dynamics design of the pre-stripper IH-DTL at GSI is sensitive to slight deviations of rf-phase and gap voltages with impact to the mean beam energy at the DTL exit. Applying the existing geometrical design, rf-voltages, and rf-phases of the DTL were re-adjusted. In simulations this re-optimized design can provide for more than 90% of transmission of an intense 15 emA beam keeping the reduction of beam brilliance below 25%.

Disruption of gel phase lipid packing efficiency by sucralose studied with merocyanine 540.

PubMed

Barker, Morgan; Kennedy, Anthony

2017-04-01

Sucralose, an artificial sweetener, displays very different behavior towards membranes than its synthetic precursor sucrose. The impact of both sugars on model dipalmitoylphosphatidylcholine model membranes was investigated using absorbance and flourescence spectroscopy and the membrane probe merocyanine 540. This probe molecule is highly sensitive to changes in membrane packing, microviscosity and polarity. This work focuses on the impact of sugars on the outer leaflet of unilamellar dipalmitoyl phosphatidylcholine model membranes. The choice of lipid permits access to the gel phase at room temperature and incorporation of the dye after liposome formation allows us to examine the direct impact of the sugar on the outer leaflet while maximizing the response of the dye to changes in the bilayer. The results demonstrate that sucrose has no impact on the packing efficiency of lipids in unilamellar DPPC vesicles in the gel phase. Conversely sucralose decreases the packing efficiency of lipids in the gel phase and results in decreased microviscosity and increased membrane fluidity, which may be as a result of water disruption at the membrane water interface. Copyright © 2017 Elsevier B.V. All rights reserved.

Sol-gel technique for the preparation of beta-cyclodextrin derivative stationary phase in open-tubular capillary electrochromatography.

PubMed

Wang, Y; Zeng, Z; Guan, N; Cheng, J

2001-07-01

A novel open-tubular capillary electrochromatography (OT-CEC) column coated with 2,6-dibutyl-beta-cyclodextrin (DB-beta-CD) was prepared using sol-gel technique. In the sol-gel approach, owing to the three-dimensional network of sol-gel and the strong chemical bond between the stationary phase and the surface of capillary columns, good chromatographic characteristics and unique selectivity in separating isomers were shown. We achieved high efficiencies of 5-14 x 10(4) plates/m for the isomeric nitrophenols using the sol-gel-derived DB-beta-CD columns. The migration time reproducibility of the separation of the isomeric nitrophenols was better than 2.2% over five runs and 4.5% from column to column. These sol-gel-coated DB-beta-CD columns have shown improved separations of isomeric aminophenols, isomeric dihydroxybenzenes and isomeric nitrophenols, in comparison with the sol-gel matrix capillary column. The influences of buffer pH and methanol solvent on separation were investigated. The chiral resolution of enantiomers such as ibuprofen and binaphthol was explored primarily.

Stopband-Extended and Size-Miniaturized Low-Pass Filter Based on Interdigital Capacitor Loaded Hairpin Resonator with Four Transmission Zeros

NASA Astrophysics Data System (ADS)

Wu, Jia-Jia; Li, Lin

2018-04-01

In this paper, a compact low-pass filter (LPF) with wide stopband is proposed based on interdigital capacitor loaded hairpin resonator. The structure composed of an upper high-impedance transmission line, a middle interdigital capacitor, and a pair of inter-coupled symmetrical stepped-impedance stubs. Detailed investigation into this structure based on even-odd mode approach reveals that up to four transmission zeros can be generated and reallocated by choosing the proper circuit parameters. And owing to the aid of transmission zeros, the fabricated quasi-elliptic LPFs experimentally demonstrate a wide 20dB stopband from 1.4fc to 5.1fc using a compact size of only 0.005 λg2.

Effect of intra-membrane C60 fullerenes on the modulus of elasticity and the mechanical resistance of gel and fluid lipid bilayers

NASA Astrophysics Data System (ADS)

Zhou, Jihan; Liang, Dehai; Contera, Sonia

2015-10-01

Penetration and partition of C60 to the lipid bilayer core are both relevant to C60 toxicity, and useful to realise C60 biomedical potential. A key aspect is the effect of C60 on bilayer mechanical properties. Here, we present an experimental study on the mechanical effect of the incorporation of C60 into the hydrophobic core of fluid and gel phase zwitterionic phosphatidylcholine (PC) lipid bilayers. We demonstrate its incorporation inside the hydrophobic lipid core and the effect on the packing of the lipids and the vesicle size using a combination of infrared (IR) spectroscopy, atomic force microscopy (AFM) and laser light scattering. Using AFM we measured the Young's modulus of elasticity (E) of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) in the absence (presence) of intra-membranous C60 at 24.5 °C. E of fluid phase supported bilayers is not altered by C60, but E increases with incorporation of C60 in gel phase bilayers. The increase is higher for longer hydrocarbon chains: 1.6 times for DPPC and 2 times for DSPC. However the mechanical resistance of gel phase bilayers of curved bilayered structures decreases with the incorporation of C60. Our combined results indicate that C60 causes a decrease in gel phase lipid mobility, i.e. an increase in membrane viscosity.

Preparation of chitosan-graft-(β-cyclodextrin) based sol-gel stationary phase for open-tubular capillary electrochromatography.

PubMed

Lü, Haixia; Li, Qingyin; Yu, Xiaowei; Yi, Jiaojiao; Xie, Zenghong

2013-07-01

A novel open-tubular CEC column coated with chitosan-graft-(β-CD) (CDCS) was prepared using sol-gel technique. In the sol-gel approach, owing to the 3D network of sol-gel and the strong chemical bond between the stationary phase and the surface of capillary columns, good chromatographic characteristics and unique selectivity in separating isomers were shown. The column efficiencies of 55,000∼163,000 plates/m for the isomeric xanthopterin and phenoxy acid herbicides using the sol-gel-derived CDCS columns were achieved. Good stabilities were demonstrated that the RSD values for the retention time of thiourea and isoxanthopterin were 1.3 and 1.4% (run to run, n = 5), 1.6 and 2.0% (day to day, n = 3), 2.9 and 3.1% (column to column, n = 3), respectively. The sol-gel-coated CDCS columns have shown improved separations of isomeric xanthopterin in comparison with CDCS-bonded capillary column. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation and evaluation of injectable Rasagiline mesylate dual-controlled drug delivery system for the treatment of Parkinson's disease.

PubMed

Jiang, Ying; Zhang, Xuemei; Mu, Hongjie; Hua, Hongchen; Duan, Dongyu; Yan, Xiuju; Wang, Yiyun; Meng, Qingqing; Lu, Xiaoyan; Wang, Aiping; Liu, Wanhui; Li, Youxin; Sun, Kaoxiang

2018-11-01

A microsphere-gel in situ forming implant (MS-Gel ISFI) dual-controlled drug delivery system was applied to a high water-soluble small-molecule compound Rasagiline mesylate (RM) for effective treatment of Parkinson's disease. This injectable complex depot system combined an in situ phase transition gel with high drug-loading and encapsulation efficiency RM-MS prepared by a modified emulsion-phase separation method and optimized by Box-Behnken design. It was evaluated for in vitro drug release, in vivo pharmacokinetics, and in vivo pharmacodynamics. We found that the RM-MS-Gel ISFI system showed no initial burst release and had a long period of in vitro drug release (60 days). An in vivo pharmacokinetic study indicated a significant reduction (p < .01) in the initial high plasma drug concentration of the RM-MS-Gel ISFI system compared to that of the single RM-MS and RM-in situ gel systems after intramuscular injection to rats. A pharmacodynamic study demonstrated a significant reduction (p < .05) in 6-hydroxydopamine-induced contralateral rotation behavior and an effective improvement (p < .05) in dopamine levels in the striatum of the lesioned side after 28 days in animals treated with the RM-MS-Gel ISFI compared with that of animals treated with saline. MS-embedded in situ phase transition gel is superior for use as a biodegradable and injectable sustained drug delivery system with a low initial burst and long period of drug release for highly hydrophilic small molecule drugs.

Characterization of the Rheological and Swelling Properties of Synthetic Alkali Silicate Gels in Order to Predict Their Behavior in ASR Damaged Concrete

NASA Astrophysics Data System (ADS)

Vayghan, Asghar Gholizadeh

Alkali-silica reaction (ASR) is a major concrete durability concern that is responsible for the deterioration of concrete infrastructure in the world. The resultant of the reaction between the cement alkali hydroxides and the metastable silicates in the aggregates is a hygroscopic and expansive alkali-silicate gel (referred to as ASR gel in this document). The swelling behavior of ASR gels determines the extent of damage to concrete structures and, as such, mitigation of ASR relies on understanding these gels and finding ways to prevent them either from formation, or from swelling after formation. This dissertation focuses on the synthesis and characterization of ASR gels with wide ranges of compositions similar to what has been reported for the filed ASR gels in the literature. The experimental work consisted of three phases as follow. Phase I: Investigation of rheology, chemistry and physics of ASR gels produced through sol-method. Inspired from the existing literature, two sol-gel methods have been developed for the synthesis of ASR gels. The rheological (primarily gelation time, yield stress, and equilibrium stress), chemical (pore solution pH, pore solution composition, osmotic pressure, solid phase composition, stoichiometry of gelation reactions) and physical (evaporable water, solid content, etc.) properties of synthetic ASR gels have been extensively investigated in this phase. Ca/Si, Na/Si and K/Si, and water content were considered as the main chemical composition variables. In order to investigate the suppressing effects of lithium on the swelling properties of ASR gels, the gels were added with lithium in a part of the experimental program. The results strongly suggested that Ca/Si has a positive effect on the yield stress of the gels and their rate of gelation. Na/Si was found to have a decreasing effect on the yield stress and gelation rate (especially at low Ca/Si levels). K/Si and Li/Si had second-order (i.e., polynomial) effects on the yield stress of the gels, causing a significant drop in this parameter followed by some increase as they approached their upper values. Na/Si and K/Si were both found contribute to the osmotic potential of the ASR gels, while increase in Ca/Si generally led to a drop in this parameter. The presence of all components (Ca, Na, and K) were found to contribute to the pH of the gels' pore solution, and Ca/Si and Na/Si showed a synergistic effect on this parameter. Lithium, on the other hand, was found to be able to drop the OH- concentration of the pore solution by a factor of five in the case of high-sodium gels, which could partially explain its ASR mitigating effect. Phase II: Investigation of the free and restrained swelling behavior, hydrophilic potential and viscoelastic properties of ASR gels produced through the "paste method". 20 gel compositions were selected (using the central composite design method) with Ca/Si, Na/Si and K/Si molar ratios varying in the ranges (0.05-0.5), (0.1-1.0) and (0.0-0.3), respectively. The gels were produced by batching appropriate amounts of certain precursors containing different chemical components. After curing, the gels were tested for the abovementioned parameters using some innovative test methods as explained in the relevant chapters. The results suggest that increasing the alkali content (Na/Si and K/Si) in ASR gels resulted in an increase in the gels' free swelling and water absorption, and a reduction in the equilibrium relative humidity (ERH). However, no significant effect was found for Ca/Si with respect to the ERH. Ca/Si was found to have a multi-episode effect on the swelling and water absorption properties of the gels. An increase in Ca/Si up to 0.18 led to a considerable reduction in the swelling strain, followed by a slight increasing effect as it approached 0.4. Further increase in Ca/Si resulted in complete elimination of swelling strain. While Na/Si and K/Si could constantly increase the free swelling strain, their excessive presence was found to have a softening effect on the gels' structure, leading to a drop in their swelling pressure. Finally, all gels were found to show viscoelastic behavior that could be best explained via Burger's model. The elastic and viscous components have been measured for each gel and related to their composition using regression. Phase III: An Extended Chemical Index Model to Predict the Fly Ash Dosage Necessary for Mitigating Alkali-Silica Reaction in Concrete . In order to have an applied and ready-to-implement contribution to the realm of alkali-silica reaction, a predictive statistical model was developed that determines the optimum fly ash dosage for ASR mitigation depending on the acceptable risk of ASR and structure's importance. (Abstract shortened by ProQuest.).

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

Armstrong, Clare L; Barrett, M; Heiss, Arno

Inelastic neutron scattering was used to study the effect of 5 and 40 mol% cholesterol on the lateral nanoscale dynamics of phospholipid membranes. By measuring the excitation spectrum at several lateral q || values (up to q || = 3 1), complete dispersion curves were determined of gel, fluid and liquid-ordered phase bilayers. The inclusion of cholesterol had a distinct effect on the collective dynamics of the bilayer s hydrocarbon chains; specifically, we observed a pronounced stiffening of the membranes on the nanometer length scale in both gel and fluid bilayers, even though they were experiencing a higher degree ofmore » molecular disorder. Also, for the first time we determined the nanoscale dynamics in the high-cholesterol liquid-ordered phase of bilayers containing cholesterol. Namely, this phase appears to be softer than fluid bilayers, but better ordered than bilayers in the gel phase.« less

Nanoscopic dynamics of phospholipid in unilamellar vesicles: Effect of gel to fluid phase transition

DOE PAGES

Sharma, V. K.; Mamontov, E.; Anunciado, D. B.; ...

2015-03-04

Dynamics of phospholipids in unilamellar vesicles (ULV) is of interest in biology, medical, and food sciences since these molecules are widely used as biocompatible agents and a mimic of cell membrane systems. We have investigated the nanoscopic dynamics of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) phospholipid in ULV as a function of temperature using elastic and quasielastic neutron scattering (QENS). The dependence of the signal on the scattering momentum transfer, which is a critical advantage of neutron scattering techniques, allows the detailed analysis of the lipid motions that cannot be carried out by other means. In agreement with a differential scanning calorimetry measurement, amore » sharp rise in the elastic scattering intensity below ca. 296 K indicates a phase transition from the high-temperature fluid phase to the low-temperature solid gel phase. The microscopic lipid dynamics exhibits qualitative differences between the solid gel phase (in a measurement at 280 K) and the fluid phase (in a measurement at a physiological temperature of 310 K). The data analysis invariably shows the presence of two distinct motions: the whole lipid molecule motion within a monolayer, or lateral diffusion, and the relatively faster internal motion of the DMPC molecule. The lateral diffusion of the whole lipid molecule is found to be Fickian in character, whereas the internal lipid motions are of localized character, consistent with the structure of the vesicles. The lateral motion slows down by an order of magnitude in the solid gel phase, whereas for the internal motion not only the time scale, but also the character of the motion changes upon the phase transition. In the solid gel phase, the lipids are more ordered and undergo uniaxial rotational motion. However, in the fluid phase, the hydrogen atoms of the lipid tails undergo confined translation diffusion rather than uniaxial rotational diffusion. The localized translational diffusion of the hydrogen atoms of the lipid tails is a manifestation of the flexibility of the chains acquired in the fluid phase. Because of this flexibility, both the local diffusivity and the confinement volume for the hydrogen atoms increase linearly from near the lipid s polar head group to the end of its hydrophobic tail. Our results present a quantitative and detailed picture of the effect of the gel-fluid phase transition on the nanoscopic lipid dynamics in ULV. Lastly, the data analysis approach developed here has a potential for probing the dynamic response of lipids to the presence of additional cell membrane components.« less

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

Wang, Meng; Yi, Ming; Tian, Wei

Here, the complex interdigitated phases have greatly frustrated attempts to document the basic features of the superconductivity in the alkali metal intercalated iron chalcogenides. Here, using elastic neutron scattering, energy-dispersive x-ray spectroscopy, and resistivity measurements, we elucidate the relations of these phases in Rb xFe ySe 2-zS z. We find (i) the iron content is crucial in stabilizing the stripe antiferromagnetic (AF) phase with rhombic iron vacancy order (y ≈ 1.5), the block AF phase with root 5 x root 5 iron vacancy order (y ≈ 1.6), and the iron vacancy-free phase (y ≈ 2); and (ii) the iron vacancy-freemore » superconducting phase (z = 0) evolves into an iron vacancy-free metallic phase with sulfur substitution (z > 1.5) due to the progressive decrease of the electronic correlation strength. Both the stripe AF phase and the block AF phase are Mott insulators. The iron-rich compounds (y > 1.6) undergo a first order transition from an iron vacancy disordered phase at high temperatures into the √5 x √5 iron vacancy ordered phase and the iron vacancy-free phase below T s. Our data demonstrate that there are miscibility gaps between these three phases. The existence of the miscibility gaps in the iron content is a key to understanding the relationship between these complicated phases.« less

Preparation and in vitro evaluation of a pluronic lecithin organogel containing ricinoleic acid for transdermal delivery.

PubMed

Boddu, Sai Hs; Bonam, Sindhu Prabha; Wei, Yangjie; Alexander, Kenneth

2014-01-01

The present study deals with the preparation and in vitro evaluation of a Pluronic lecithin organogel gel containing ricinoleic acid for transdermal delivery. Blank Pluronic lecithin organogel gels were prepared using ricinoleic acid as the oil phase and characterized for pH, viscosity, gelation temperature, and microscopic structure. The optimized Pluronic lecithin organogel gel formulation was further evaluated using ketoprofen (10%) and dexamethasone (0.5%) as model drugs. The stability and in vitro permeability of ketoprofen and dexamethasone was evaluated and compared with the corresponding control formulation (Pluronic lecithin organogel gel made with isopropyl palmitate as the oil phase). The pH and viscosity of blank Pluronic lecithin organogel gel prepared with ricinoleic acid was comparable with the isopropyl palmitate Pluronic lecithin organogel gel. The thixotropic property of ricinoleic acid Pluronic lecithin organogel gel was found to be better than the control. Drug-loaded Pluronic lecithin organogel gels behaved in a similar manner and all formulations were found to be stable at 25 degrees C, 35 degrees C, and 40 degrees C for up to 35 days. The penetration profile of dexamethasone was similar from both the Pluronic lecithin organogel gels, while the permeability for ketoprofen from Pluronic lecithin organogel gel containing ricinoleic acid was found to be three times higher as compared to the control formulation.

Deswelling kinetics of polyacrylate gels in solutions of cetyltrimethylammonium bromide.

PubMed

Nilsson, Peter; Hansson, Per

2007-08-23

The deswelling kinetics of single sodium polyacrylate gel beads (radius 40-160 microm) in aqueous solutions of cetyltrimethylammonium bromide under conditions of forced convection are investigated using micromanipulator assisted light microscopy. The purpose of the study is to further evaluate a previously published model (J. Phys. Chem. B 2003, 107, 9203) using a higher homolog surfactant. For gels with expected fast deswelling (small gel size/low surfactant concentration) and/or in low electrolyte concentration, the model is found to correctly predict the deswelling characteristics of the gel beads. However, for some gels with expected slow deswelling, especially in high electrolyte concentration (10 mM NaBr), the model widely underestimates the required deswelling time. The reason for this is argued to be the longer time frame and high bromide concentration allowing the formation of a denser, more ordered structure in the surface phase, which resists the deformation and reorganization of material necessary for deswelling. Unexpectedly long lag times before the start of deswelling are also found for gels in low surfactant concentration, indicating that a relatively high surfactant concentration in the gel, greatly exceeding the critical aggregation concentration, is needed to start formation of a collapsed surface phase. This critical surfactant concentration is found to be dependent on initial gel radius, as small gels require a relatively higher concentration to initiate collapse.

The gelation influence on diffusion and conductivity enhancement effect in renewable ionic gels based on a LMWG.

PubMed

Bielejewski, M; Rachocki, A; Kaszyńska, J; Tritt-Goc, J

2018-02-21

This paper reports the interdisciplinary study on molecular dynamics, ionic interactions and electrical conductivity in a quaternary ammonium salt (TMABr) ionogel based on a low molecular weight gelator (LMWG) in a wide range of electrolyte molar concentrations. The thermal scanning conductometry (TSC) was used to investigate the electric properties of the ionogels. The prepared TMABr/H 2 O/LMWG ionogel exhibits better ion transport properties than the dissociated TMA + cation in solution. The enhanced ionic conductivity effect (EICE) was observed in the concentration range of the TMABr salt up to 1 M. To investigate the transport properties of the TMA + cation and solvent molecules in the gel and sol phase, the NMR diffusiometry method was used. The field-cycling relaxometry method (FFC NMR) was applied to study the local motions of the electrolyte at the surface of the gelator matrix. On the basis of the obtained data, the higher ionic conductivity observed in the gel phase has been related to the microstructure of the gel matrix. The possible explanation for the origin of this effect has been given. The investigated system is a thermally reversible physical gel, all registered data were reproducible upon transforming the sample from gel to sol and back to the gel state, confirming the enhancement effect as a permanent property of the investigated ionogels. Therefore, the EICE has been proposed to be used as an internal sensor to monitor the condition of the ionogel phase, thus making them smart materials.

Theoretical and experimental study of the bending influence on the capacitance of interdigitated micro-electrodes patterned on flexible substrates

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

Molina-Lopez, F.; Briand, D.; Rooij, N. F. de

2013-11-07

Interdigitated electrodes are common structures in the fields of microelectronics and MEMS. Recent developments in flexible electronics compel an understanding of such structures under bending constraints. In this work, the behavior of interdigitated micro-electrodes when subjected to circular bending has been theoretically and experimentally studied through changes in capacitance. An analytical model has been developed to calculate the expected variation in capacitance of such structures while undergoing outward and inward bending along the direction perpendicular to the electrodes. The model combines conformal mapping techniques to account for the electric field redistribution and fundamental aspects of solid mechanics in order tomore » define the geometrical deformation of the electrodes while bending. To experimentally verify our theoretical predictions, several interdigitated electrode structures with different geometries were fabricated on polymeric substrates by means of photolithography. The samples, placed in a customized bending setup, were bent to controlled radii of curvature while measuring their capacitance. A maximum variation in capacitance of less than 3% was observed at a minimum radius of curvature of 2.5 mm for all the devices tested with very thin electrodes whereas changes of up to 7% were found on stiffer, plated electrodes. Larger or smaller variations would be possible, in theory, by adjusting the geometry of the device. This work establishes a useful predictive tool for the design and evaluation of truly flexible/bendable electronics consisting of interdigitated structures, allowing one to tune the bending influence on the capacitance value through geometrical design.« less

Interdigitated array of Pt electrodes for electrical stimulation and engineering of aligned muscle tissue.

PubMed

Ahadian, Samad; Ramón-Azcón, Javier; Ostrovidov, Serge; Camci-Unal, Gulden; Hosseini, Vahid; Kaji, Hirokazu; Ino, Kosuke; Shiku, Hitoshi; Khademhosseini, Ali; Matsue, Tomokazu

2012-09-21

Engineered skeletal muscle tissues could be useful for applications in tissue engineering, drug screening, and bio-robotics. It is well-known that skeletal muscle cells are able to differentiate under electrical stimulation (ES), with an increase in myosin production, along with the formation of myofibers and contractile proteins. In this study, we describe the use of an interdigitated array of electrodes as a novel platform to electrically stimulate engineered muscle tissues. The resulting muscle myofibers were analyzed and quantified in terms of their myotube characteristics and gene expression. The engineered muscle tissues stimulated through the interdigitated array of electrodes demonstrated superior performance and maturation compared to the corresponding tissues stimulated through a conventional setup (i.e., through Pt wires in close proximity to the muscle tissue). In particular, the ES of muscle tissue (voltage 6 V, frequency 1 Hz and duration 10 ms for 1 day) through the interdigitated array of electrodes resulted in a higher degree of C2C12 myotube alignment (∼80%) as compared to ES using Pt wires (∼65%). In addition, higher amounts of C2C12 myotube coverage area, myotube length, muscle transcription factors and protein biomarkers were found for myotubes stimulated through the interdigitated array of electrodes compared to those stimulated using the Pt wires. Due to the wide array of potential applications of ES for two- and three-dimensional (2D and 3D) engineered tissues, the suggested platform could be employed for a variety of cell and tissue structures to more efficiently investigate their response to electrical fields.

Three-Phase Coexistence in Colloidal Rod-Plate Mixtures.

PubMed

Woolston, Phillip; van Duijneveldt, Jeroen S

2015-09-01

Aqueous suspensions of clay particles, such as montmorillonite (MMT) platelets and sepiolite (Sep) rods, tend to form gels at concentrations around 1 vol %. For Sep rods, adsorbing sodium polyacrylate to the surface allows for an isotropic-nematic phase separation to be seen instead. Here, MMT is added to such Sep suspensions, resulting in a complex phase behavior. Across a range of clay concentrations, separation into three phases is observed: a lower, nematic phase dominated by Sep rods, a MMT-rich middle layer, which is weakly birefringent and probably a gel, and a dilute top phase. Analysis of phase volumes suggests that the middle layer may contain as much as 6 vol % MMT.

EFFECTS OF TEMPERATURE ON TRICHLOROETHYLENE DESORPTION FROM SILICA GEL AND NATURAL SEDIMENTS. 1. ISOTHERMS. (R822626)

EPA Science Inventory

Aqueous phase isotherms were calculated from vapor phase desorption isotherms
measured at 15, 30, and 60 C for
trichloroethylene on a silica gel, an aquifer sediment, a soil, a sand fraction,
and a clay and silt fraction, all at...

Characterizing the Sensitivity, Selectivity, and Reversibility of the Metal-Doped Phthalocyanine Thin-Films Used with the Interdigitated Gate Electrode Field-Effect Transistor (IGEFET) to Detect Organophosphorous Compounds and Nitrogen Dioxide

DTIC Science & Technology

1991-12-01

Susan, and my children , Abigail and Benjamin. Their love, patience, and support made the sacrifices bearable. ii Table of Contents Acknowledgements...63 e -72 -81 10 100 1000 10000 100000 1000000 Frequency (log scale) *Purge 01 a Challenge 02 (105 Porn Boron Trifluoride) ePurge #2 Figure C-85. Phase... porn Ammonia) * Purge #2 Figure D-85.Gatin versus Frequency Response of IGEFET Microsensor for it Series of Room Air Purges and Challenge Gas Exposures

Isotropic-nematic phase transition in aqueous sepiolite suspensions.

PubMed

Woolston, Phillip; van Duijneveldt, Jeroen S

2015-01-01

Aqueous suspensions of sepiolite clay rods in water tend to form gels on increase of concentration. Here it is shown how addition of a small amount (0.1% of the clay mass) of a common stabiliser for clay suspensions, sodium polyacrylate, can allow the observation of an isotropic-nematic liquid crystal phase transition. This transition was found to move to higher clay concentrations upon adding NaCl, with samples containing 10(-3) M salt or above only displaying a gel phase. Even samples that initially formed liquid crystals had a tendency to form gels after several weeks, possibly due to Mg(2+) ions leaching from the clay mineral. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Interdigitated Eutectic Alloy Foil Anodes for Rechargeable Batteries

DOE PAGES

Kreder, III, Karl J.; Heligman, Brian T.; Manthiram, Arumugam

2017-09-19

An interdigitated eutectic alloy (IdEA) foil is presented as a framework for the development of alloy anodes with a capacity that is significantly higher than that of the traditional graphite/copper assembly. In conclusion, it is a simple, low-cost approach that can be applied to a broad range of alloy systems with various working ions such as Li, Na, or Mg.

A Pilot Study Measuring the Distribution and Permeability of a Vaginal HIV Microbicide Gel Vehicle Using Magnetic Resonance Imaging, Single Photon Emission Computed Tomography/Computed Tomography, and a Radiolabeled Small Molecule.

PubMed

Fuchs, Edward J; Schwartz, Jill L; Friend, David R; Coleman, Jenell S; Hendrix, Craig W

2015-11-01

Vaginal microbicide gels containing tenofovir have proven effective in HIV prevention, offering the advantage of reduced systemic toxicity. We studied the vaginal distribution and effect on mucosal permeability of a gel vehicle. Six premenopausal women were enrolled. In Phase 1, a spreading gel containing (99m)technetium-DTPA ((99m)Tc) radiolabel and gadolinium contrast for magnetic resonance imaging (MRI) was dosed intravaginally. MRI was obtained at 0.5, 4, and 24 h, and single photon emission computed tomography with conventional computed tomography (SPECT/CT) at 1.5, 5, and 25 h postdosing. Pads and tissues were measured for activity to determine gel loss. In Phase 2, nonoxynol-9 (N-9), containing (99m)Tc-DTPA, was dosed as a permeability control; permeability was measured in blood and urine for both phases. SPECT/CT showed the distribution of spreading gel throughout the vagina with the highest concentration of radiosignal in the fornices and ectocervix; signal intensity diminished over 25 h. MRI showed the greatest signal accumulation in the fornices, most notably 1-4 h postdosing. The median (interquartile range) isotope signal loss from the vagina through 6 h was 29.1% (15.8-39.9%). Mucosal permeability to (99m)Tc-DTPA following spreading gel was negligible, in contrast to N-9, with detectable radiosignal in plasma, peaking at 8 h (5-12). Following spreading gel dosing, 0.004% (0.001-2.04%) of the radiosignal accumulated in urine over 12 h compared to 8.31% (7.07-11.01%) with N-9, (p=0.043). Spreading gel distributed variably throughout the vagina, persisting for 24 h, with signal concentrating in the fornices and ectocervix. The spreading gel had no significant effect on vaginal mucosal permeability.

Performance enhancement of Pt/TiO2/Si UV-photodetector by optimizing light trapping capability and interdigitated electrodes geometry

NASA Astrophysics Data System (ADS)

Bencherif, H.; Djeffal, F.; Ferhati, H.

2016-09-01

This paper presents a hybrid approach based on an analytical and metaheuristic investigation to study the impact of the interdigitated electrodes engineering on both speed and optical performance of an Interdigitated Metal-Semiconductor-Metal Ultraviolet Photodetector (IMSM-UV-PD). In this context, analytical models regarding the speed and optical performance have been developed and validated by experimental results, where a good agreement has been recorded. Moreover, the developed analytical models have been used as objective functions to determine the optimized design parameters, including the interdigit configuration effect, via a Multi-Objective Genetic Algorithm (MOGA). The ultimate goal of the proposed hybrid approach is to identify the optimal design parameters associated with the maximum of electrical and optical device performance. The optimized IMSM-PD not only reveals superior performance in terms of photocurrent and response time, but also illustrates higher optical reliability against the optical losses due to the active area shadowing effects. The advantages offered by the proposed design methodology suggest the possibility to overcome the most challenging problem with the communication speed and power requirements of the UV optical interconnect: high derived current and commutation speed in the UV receiver.

Thermal stress in flexible interdigital transducers with anisotropic electroactive cellulose substrates

NASA Astrophysics Data System (ADS)

Yoon, Sean J.; Kim, Jung Woong; Kim, Hyun Chan; Kang, Jinmo; Kim, Jaehwan

2017-12-01

Thermal stress in flexible interdigital transducers a reliability concern in the development of flexible devices, which may lead to interface delamination, stress voiding and plastic deformation. In this paper, a mathematical model is presented to investigate the effect of material selections on the thermal stress in interdigital transducers. We modified the linear relationships in the composite materials theory with the effect of high curvature, anisotropic substrate and small substrate thickness. We evaluated the thermal stresses of interdigital transducers, fabricated with various electrodes, insulators and substrate materials for the comparison. The results show that, among various insulators, organic polymer developed the highest stress level while oxide showed the lowest stress level. Aluminium shows a higher stress level and curvature as an electrode than gold. As substrate materials, polyimide and electroactive cellulose show similar stress levels except the opposite sign convention to each other. Polyimide shows positive curvatures while electroactive cellulose shows negative curvatures, which is attributed to the stress and thermal expansion state of the metal/insulator composite. The results show that the insulator is found to be responsible for the confinement across the metal lines while the substrate is responsible for the confinement along the metal lines.

Expression of Fas, FasL, caspase-8 and other factors of the extrinsic apoptotic pathway during the onset of interdigital tissue elimination.

PubMed

Svandova, E Budisova; Vesela, B; Lesot, H; Poliard, A; Matalova, E

2017-04-01

Elimination of the interdigital web is considered to be the classical model for assessing apoptosis. So far, most of the molecules described in the process have been connected to the intrinsic (mitochondrial) pathway. The extrinsic (receptor mediated) apoptotic pathway has been rather neglected, although it is important in development, immunomodulation and cancer therapy. This work aimed to investigate factors of the extrinsic apoptotic machinery during interdigital regression with a focus on three crucial initiators: Fas, Fas ligand and caspase-8. Immunofluorescent analysis of mouse forelimb histological sections revealed abundant expression of these molecules prior to digit separation. Subsequent PCR Array analyses indicated the expression of several markers engaged in the extrinsic pathway. Between embryonic days 11 and 13, statistically significant increases in the expression of Fas and caspase-8 were observed, along with other molecules involved in the extrinsic apoptotic pathway such as Dapk1, Traf3, Tnsf12, Tnfrsf1A and Ripk1. These results demonstrate for the first time the presence of extrinsic apoptotic components in mouse limb development and indicate novel candidates in the molecular network accompanying the regression of interdigital tissue during digitalisation.

Crystallization of Na2O-SiO2 gel and glass

NASA Technical Reports Server (NTRS)

Neilson, G. F.; Weinberg, M. C.

1984-01-01

The crystallization behavior of a 19 wt pct soda silica gel and gel-derived glass was compared to that of the ordinary glass of the same composition. Both bulk and ground glass samples were utilized. X-ray diffraction measurements were made to identify the crystalline phases and gauge the extent of crystallization. It was found that the gel crystallized in a distinctive manner, while the gel glass behavior was not qualitatively different from that of the ordinary glass.

Econazole nitrate foam 1% for the treatment of tinea pedis: results from two double-blind, vehicle-controlled, phase 3 clinical trials.

PubMed

Elewski, Boni E; Vlahovic, Tracey C

2014-07-01

Econazole nitrate is a broad-spectrum topical antifungal with activity against a variety of dermatophytes and yeasts. A new topical dosage form, econazole nitrate topical foam 1%, utilizing patented Proderm Technology® has been developed for treatment of interdigital tinea pedis. To evaluate econazole nitrate foam 1% versus foam vehicle for treatment of interdigital tinea pedis. Two randomized, double-blind, parallel-group, vehicle-controlled, multicenter studies enrolled males and females ≥12 years old with a clinical diagnosis of interdigital tinea pedis and baseline fungal culture positive for a dermatophyte. Subjects applied econazole nitrate foam 1% (n=246) or foam vehicle (n=249) once daily for 4 weeks. The primary endpoint was proportion of subjects achieving a complete cure (negative KOH, negative fungal culture, complete resolution of all signs and symptoms) at 2 weeks post-treatment (Day 43). Secondary endpoints included mycologic cure (negative KOH and negative culture) and effective treatment (mycologic cure + no or mild erythema and/or scaling and all other signs and symptoms absent). The complete cure rate at Day 43 was 24.3% for econazole nitrate foam 1% vs 3.6% for foam vehicle. In addition, higher rates of mycologic cure (67.6% vs 16.9%) and effective treatment (48.6% vs 10.8%) were observed with econazole nitrate foam 1% versus the foam vehicle. There were few adverse events and only nasopharyngitis and headache were experienced by >1% of subjects. No serious adverse events were reported for econazole nitrate foam 1%. Econazole nitrate foam 1% exhibited superiority over foam vehicle for the primary and secondary endpoints with a high mycologic cure rate for all pathogens evaluated. Econazole nitrate foam 1% was safe and well tolerated with a safety profile comparable with the foam vehicle. Econazole nitrate foam 1% presents a novel alternative for the management of tinea pedis.

Amperometric detector for gas chromatography based on a silica sol-gel solid electrolyte.

PubMed

Steinecker, William H; Miecznikowski, Krzysztof; Kulesza, Pawel J; Sandlin, Zechariah D; Cox, James A

2017-11-01

An electrochemical cell comprising a silica sol-gel solid electrolyte, a working electrode that protrudes into a gas phase, and reference and counter electrodes that contact the solid electrolyte comprises an amperometric detector for gas chromatography. Under potentiostatic conditions, a current related to the concentration of an analyte in the gas phase is produced by its oxidation at the three-phase boundary among the sol-gel, working electrode, and the gas phase. The sol-gel is processed to contain an electrolyte that also serves as a humidistat to maintain a constant water activity even in the presence the gas chromatographic mobile phase. Response was demonstrated toward a diverse set of analytes, namely hydrogen, 1,2-ethandithiol, phenol, p-cresol, and thioanisole. Using flow injection amperometry of hydrogen with He as the carrier gas, 90% of the steady-state current was achieved in < 1s at a flow rate of 20mLmin -1 . A separation of 1,2-ethandithiol, phenol, p-cresol, and thioanisole at a 2.2mLmin -1 flow rate was achieved with respective detection limits (k = 3 criterion) of 4, 1, 3, and 70 ppmv when the working electrode potential was 800mV. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of phloretin on the binding of 1-anilino-8-naphtalene sulfonate (ANS) to 1,2-Dimyristoyl-sn-glycero-3-phosphocoline (DMPC) vesicles in the gel and liquid-crystalline state.

PubMed

Cutró, Andrea C; Montich, Guillermo; Roveri, Oscar A

2015-02-01

Phloretin is a known modifier of the internal dipole potential of lipid membranes. We studied the interaction of phloretin with model lipid membranes and how it influences the membrane dipole organization using ANS as fluorescent probe. The fluorescence increase observed when ANS binds to DMPC liposomes in gel phase (13 °C) was 2.5 times larger in the presence of phloretin. This effect was due to an increase in ANS affinity, which can be related to the known capability of phloretin in decreasing the dipole potential. Conversely, when the experiments were carried out at 33 °C (liquid crystalline phase), phloretin completely inhibited the increase in ANS fluorescence. In addition, phloretin only affected the electrical properties of the membrane in the gel phase, whereas it modifies structural ones in the liquid-crystalline state. We postulate that phloretin was bound only to the DMPC interface in the gel phase decreasing the surface negative charge density without modifying the structural properties of the ANS binding sites. In the liquid-crystalline phase instead, it increased the accessibility of water to the ANS binding sites decreasing the intrinsic affinity and the fluorescence quantum yield of ANS.

Development of cost-effective noncarbon sorbents for Hg(0) removal from coal-fired power plants.

PubMed

Lee, Joo-Youp; Ju, Yuhong; Keener, Tim C; Varma, Rajender S

2006-04-15

Noncarbonaceous materials or mineral oxides (silica gel, alumina, molecular sieves, zeolites, and montmorillonite) were modified with various functional groups such as amine, amide, thiol, urea, and active additives such as elemental sulfur, sodium sulfide, and sodium polysulfide to examine their potential as sorbents for the removal of elemental mercury (Hg(0)) vapor at coal-fired utility power plants. A number of sorbent candidates such as amine- silica gel, urea- silica gel, thiol- silica gel, amide-silica gel, sulfur-alumina, sulfur-molecular sieve, sulfur-montmorillonite, sodium sulfide-montmorillonite, and sodium polysulfide-montmorillonite, were synthesized and tested in a lab-scale fixed-bed system under an argon flow for screening purposes at 70 degrees C and/or 140 degrees C. Several functionalized silica materials reported in previous studies to effectively control heavy metals in the aqueous phase showed insignificant adsorption capacities for Hg(0) control in the gas phase, suggesting that mercury removal mechanisms in both phases are different. Among elemental sulfur-, sodium sulfide-, and sodium polysulfide-impregnated inorganic samples, sodium polysulfide-impregnated montmorillonite K 10 showed a moderate adsorption capacity at 70 degrees C, which can be used for sorbent injection prior to the wet FGD system.

Hierarchical Sol-Gel Transition Induced by Thermosensitive Self-Assembly of an ABC Triblock Polymer in an Ionic Liquid

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

Kitazawa, Yuzo; Ueki, Takeshi; McIntosh, Lucas D.

2016-04-29

Here we investigate a hierarchical morphology change and accompanying sol–gel transition using a doubly thermosensitive ABC-triblock copolymer in an ionic liquid (IL). The triblock copolymer contains two different lower critical solution temperature (LCST) thermosensitive polymers, poly(benzyl methacrylate) (PBnMA) and poly(2-phenylethyl methacrylate) (PPhEtMA), as the end blocks and poly(methyl methacrylate) (PMMA) as the middle block (PBnMA-b-PMMA-b-PPhEtMA: BMP). BMP undergoes a hierarchical phase transition corresponding to the self-assembly of each of the thermosensitive blocks in the IL, and a sol–gel transition was observed in concentrated, above 10 wt %, polymer solutions. The gelation behavior was affected by polymer concentration, and at 20more » wt %, the BMP/IL composite showed a phase transition, with increasing temperature, from solution through a jammed micelle suspension to a physically cross-linked gel. For each phase was formed reversibly and rapidly over the corresponding temperature range. Finally, the jammed micelle and cross-linked gel states were characterized using viscoelastic measurements and small-angle X-ray scattering (SAXS).« less

Continuous synthesis of drug-loaded nanoparticles using microchannel emulsification and numerical modeling: effect of passive mixing

PubMed Central

Ortiz de Solorzano, Isabel; Uson, Laura; Larrea, Ane; Miana, Mario; Sebastian, Victor; Arruebo, Manuel

2016-01-01

By using interdigital microfluidic reactors, monodisperse poly(d,l lactic-co-glycolic acid) nanoparticles (NPs) can be produced in a continuous manner and at a large scale (~10 g/h). An optimized synthesis protocol was obtained by selecting the appropriated passive mixer and fluid flow conditions to produce monodisperse NPs. A reduced NP polydispersity was obtained when using the microfluidic platform compared with the one obtained with NPs produced in a conventional discontinuous batch reactor. Cyclosporin, an immunosuppressant drug, was used as a model to validate the efficiency of the microfluidic platform to produce drug-loaded monodisperse poly(d,l lactic-co-glycolic acid) NPs. The influence of the mixer geometries and temperatures were analyzed, and the experimental results were corroborated by using computational fluid dynamic three-dimensional simulations. Flow patterns, mixing times, and mixing efficiencies were calculated, and the model supported with experimental results. The progress of mixing in the interdigital mixer was quantified by using the volume fractions of the organic and aqueous phases used during the emulsification–evaporation process. The developed model and methods were applied to determine the required time for achieving a complete mixing in each microreactor at different fluid flow conditions, temperatures, and mixing rates. PMID:27524896

Continuous synthesis of drug-loaded nanoparticles using microchannel emulsification and numerical modeling: effect of passive mixing.

PubMed

Ortiz de Solorzano, Isabel; Uson, Laura; Larrea, Ane; Miana, Mario; Sebastian, Victor; Arruebo, Manuel

2016-01-01

By using interdigital microfluidic reactors, monodisperse poly(d,l lactic-co-glycolic acid) nanoparticles (NPs) can be produced in a continuous manner and at a large scale (~10 g/h). An optimized synthesis protocol was obtained by selecting the appropriated passive mixer and fluid flow conditions to produce monodisperse NPs. A reduced NP polydispersity was obtained when using the microfluidic platform compared with the one obtained with NPs produced in a conventional discontinuous batch reactor. Cyclosporin, an immunosuppressant drug, was used as a model to validate the efficiency of the microfluidic platform to produce drug-loaded monodisperse poly(d,l lactic-co-glycolic acid) NPs. The influence of the mixer geometries and temperatures were analyzed, and the experimental results were corroborated by using computational fluid dynamic three-dimensional simulations. Flow patterns, mixing times, and mixing efficiencies were calculated, and the model supported with experimental results. The progress of mixing in the interdigital mixer was quantified by using the volume fractions of the organic and aqueous phases used during the emulsification-evaporation process. The developed model and methods were applied to determine the required time for achieving a complete mixing in each microreactor at different fluid flow conditions, temperatures, and mixing rates.

Identification of the hydrate gel phases present in phosphate-modified calcium aluminate binders

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

Chavda, Mehul A.; Bernal, Susan A.; Apperley, David C.

The conversion of hexagonal calcium aluminate hydrates to cubic phases in hydrated calcium aluminate cements (CAC) can involve undesirable porosity changes and loss of strength. Modification of CAC by phosphate addition avoids conversion, by altering the nature of the reaction products, yielding a stable amorphous gel instead of the usual crystalline hydrate products. Here, details of the environments of aluminium and phosphorus in this gel were elucidated using solid-state NMR and complementary techniques. Aluminium is identified in both octahedral and tetrahedral coordination states, and phosphorus is present in hydrous environments with varying, but mostly low, degrees of crosslinking. A {supmore » 31}P/{sup 27}Al rotational echo adiabatic passage double resonance (REAPDOR) experiment showed the existence of aluminium–phosphorus interactions, confirming the formation of a hydrated calcium aluminophosphate gel as a key component of the binding phase. This resolves previous disagreements in the literature regarding the nature of the disordered products forming in this system.« less

Multiscale understanding of tricalcium silicate hydration reactions.

PubMed

Cuesta, Ana; Zea-Garcia, Jesus D; Londono-Zuluaga, Diana; De la Torre, Angeles G; Santacruz, Isabel; Vallcorba, Oriol; Dapiaggi, Monica; Sanfélix, Susana G; Aranda, Miguel A G

2018-06-04

Tricalcium silicate, the main constituent of Portland cement, hydrates to produce crystalline calcium hydroxide and calcium-silicate-hydrates (C-S-H) nanocrystalline gel. This hydration reaction is poorly understood at the nanoscale. The understanding of atomic arrangement in nanocrystalline phases is intrinsically complicated and this challenge is exacerbated by the presence of additional crystalline phase(s). Here, we use calorimetry and synchrotron X-ray powder diffraction to quantitatively follow tricalcium silicate hydration process: i) its dissolution, ii) portlandite crystallization and iii) C-S-H gel precipitation. Chiefly, synchrotron pair distribution function (PDF) allows to identify a defective clinotobermorite, Ca 11 Si 9 O 28 (OH) 2 . 8.5H 2 O, as the nanocrystalline component of C-S-H. Furthermore, PDF analysis also indicates that C-S-H gel contains monolayer calcium hydroxide which is stretched as recently predicted by first principles calculations. These outcomes, plus additional laboratory characterization, yielded a multiscale picture for C-S-H nanocomposite gel which explains the observed densities and Ca/Si atomic ratios at the nano- and meso- scales.

Ion-exchange controls the kinetics of deswelling of polyelectrolyte microgels in solutions of oppositely charged surfactant.

PubMed

Nilsson, Peter; Hansson, Per

2005-12-22

The kinetics of deswelling of sodium polyacrylate microgels (radius 30-140 microm) in aqueous solutions of dodecyltrimethylammonium bromide is investigated by means of micropipet-assisted light microscopy. The purpose of the study is to test a recent model (J. Phys. Chem. B 2003, 107, 9203) proposing that the rate of the volume change is controlled by the transport of surfactant from the solution to the gel core (ion exchange) via the surfactant-rich surface phase appearing in the gel during the volume transition. Equilibrium swelling characteristics of the gel network in surfactant-free solutions and with various amounts of surfactant present are presented and discussed with reference to related systems. A relationship between gel volume and degree of surfactant binding is determined and used in theoretical predictions of the deswelling kinetics. Experimental data for single gel beads observed during deswelling under conditions of forced convection are presented and compared with model calculations. It is demonstrated that the dependences of the kinetics on initial gel size, the surfactant concentration in the solution, and the liquid flow rate are well accounted for by the model. It is concluded that the deswelling rates of the studied gels are strongly influenced by the mass transport of surfactant between gel and solution (stagnant layer diffusion), but only to a minor extent by the transport through the surface phase. The results indicate that, during the volume transition, swelling equilibrium (network relaxation/transport of water) is established on a relatively short time scale and, therefore, can be treated as independent of the ion-exchange kinetics. Theoretical aspects of the kinetics and mechanisms of surfactant transport through the surface phase are discussed.

Thermosetting gels with modulated gelation temperature for ophthalmic use: the rheological and gamma scintigraphic studies.

PubMed

Wei, Gang; Xu, Hui; Ding, Ping Tian; Li, San Ming; Zheng, Jun Min

2002-09-18

For ophthalmic drug delivery, Pluronic F127 solutions have a phase transition temperature too low for them to be instilled into the eye at room temperature. Refrigerator storage is usually required to make administration easier, whereas the potential irritation of cold to the sensitive ocular tissues may result in poor topical bioavailability. The purpose of this study is to develop a thermosetting gel with a suitable phase transition temperature by combining Pluronic analogs and to examine the influence of incorporating mucoadhesive polysaccharide, sodium hyaluronate (HA-Na), on the ocular retention of the gel. Dynamic rheological method and single photon emission computing tomography (SPECT) technique were used to ex/in vivo evaluate the thermosetting gels, respectively. An optimized formulation containing 21% F127 and 10% F68 increased the phase transition temperature by 9 degrees C as evaluated by elasticity modulus compared to that of individual 21% F127 solution. Rheological behaviors of the Pluronic solutions showed that the combined Pluronic formulation was free flowing liquid below 25 degrees C and converted to a firm gel under the physiological condition. Furthermore, this formulation possessed the highest viscosity both before and after tear dilution at 35 degrees C. Gamma scintigraphic data demonstrated that the clearance of the thermosetting gel labeled with 99mTc-DTPA was significantly delayed with respect to the phosphate buffered solution, and at least a threefold increase of the corneal residence time was achieved. However, no further improvement in the ocular retention was observed when adding HA-Na into the thermosetting gel due to the substantially decreased gel strength. Copyright 2002 Elsevier Science B.V.

Aptamer entrapment in microfluidic channel using one-step sol-gel process, in view of the integration of a new selective extraction phase for lab-on-a-chip.

PubMed

Perréard, Camille; d'Orlyé, Fanny; Griveau, Sophie; Liu, Baohong; Bedioui, Fethi; Varenne, Anne

2017-10-01

There is a great demand for integrating sample treatment into μTASs. In this context, we developed a new sol-gel phase for extraction of trace compounds in complex matrices. For this purpose, the incorporation of aptamers in silica-based gel within PDMS/glass microfluidic channels was performed for the first time by a one-step sol-gel process. The effective gel attachment onto microchannel walls and aptamer incorporation in the polymerized gel were evaluated using fluorescence microscopy. A good gel stability and aptamer incorporation inside the microchannel was demonstrated upon rinsing and over storage time. The ability of gel-encapsulated aptamers to interact with its specific target (either sulforhodamine B as model fluorescent target, or diclofenac, a pain killer drug) was assessed too. The binding capacity of entrapped aptamers was quantified (in the micromolar range) and the selectivity of the interaction was evidenced. Preservation of aptamers binding affinity to target molecules was therefore demonstrated. Dissociation constant of the aptamer-target complex and interaction selectivity were evaluated similar to those in bulk solution. This opens the way to new selective on-chip SPE techniques for sample pretreatment. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Regular and irregular deswelling of polyacrylate and hyaluronate gels induced by oppositely charged surfactants.

PubMed

Nilsson, Peter; Hansson, Per

2008-09-15

The deswelling kinetics of macroscopic polyacrylate (PA) gels in solutions of dodecyltrimethylammonium bromide (C(12)TAB) and cetyltrimethylammonium bromide (C(16)TAB), with and without added sodium bromide, as well as hyaluronate (HA) gels in solutions of cetylpyridinium chloride (CPC) are investigated. Additional data are also provided by small-angle X-ray scattering and microgel experiments. The purpose is to study the deswelling behavior of (1) regularly deswelling gels, for which the deswelling is successfully described using a core/shell model earlier employed for microgels, and (2) irregularly deswelling gels, where the gel turns into a balloon-like structure with a dense outer layer surrounding a liquid-filled core. For regularly deswelling gels, the deswelling of PA/C(12)TAB is found to be controlled by diffusion through both stagnant layer and collapsed surface phase, while for PA/C(16)TAB it is found to be controlled mainly by the latter. The difference in deswelling rate between the two is found to correspond to the difference in surfactant diffusion coefficient in the surface phase. Factors found to promote irregular deswelling, described as balloon formation, are rapid surfactant binding, high bromide and surfactant concentration, longer surfactant chain length, and macroscopic gel size. Scattering data indicating a cubic structure for HA/CPC complexes are reported.

Pressure-temperature phase behavior of mixtures of natural sphingomyelin and ceramide extracts.

PubMed

Barriga, Hanna M G; Parsons, Edward S; McCarthy, Nicola L C; Ces, Oscar; Seddon, John M; Law, Robert V; Brooks, Nicholas J

2015-03-31

Ceramides are a group of sphingolipids that act as highly important signaling molecules in a variety of cellular processes including differentiation and apoptosis. The predominant in vivo synthetic pathway for ceramide formation is via sphingomyelinase catalyzed hydrolysis of sphingomyelin. The biochemistry of this essential pathway has been studied in detail; however, there is currently a lack of information on the structural behavior of sphingomyelin- and ceramide-rich model membrane systems, which is essential for developing a bottom-up understanding of ceramide signaling and platform formation. We have studied the lyotropic phase behavior of sphingomyelin-ceramide mixtures in excess water as a function of temperature (30-70 °C) and pressure (1-200 MPa) by small- and wide-angle X-ray scattering. At low ceramide concentrations the mixtures form the ripple gel phase (P(β)') below the gel transition temperature for sphingomyelin, and this observation has been confirmed by atomic force microscopy. Formation of the ripple gel phase can also be induced at higher temperatures via the application of hydrostatic pressure. At high ceramide concentration an inverse hexagonal phase (HII) is formed coexisting with a cubic phase.

Sol-Gel synthesis of MgO-SiO2 glass compositions having stable liquid-liquid immiscibility

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.

1987-01-01

MgO-SiO2 glasses containing up to 15 mol % MgO, which could not have been prepared by the conventional glass melting method due to the presence of stable liquid-liquid immiscibility, were synthesized by the sol-gel technique. Clear and transparent gels were obtained from the hydrolysis and polycondensation of silicon tetraethoxide (TEOS) and magnesium nitrate hexahydrate when the water/TEOS mole ratio was four or more. The gelling time decreased with increase in magnesium content, water/TEOS ratio, and reaction temperature. Magnesium nitrate hexahydrate crystallized out of the gels containing 15 and 20 mol % MgO on slow drying. This problem was partially alleviated by drying the gels quickly at higher temperatures. Monolithic gel samples were prepared using glycerol as the drying control additive. The gels were subjected to various thermal treatments and characterized by several methods. No organic groups could be detected in the glasses after heat treatments to approx. 800 C, but trace amounts of hydroxyl groups were still present. No crystalline phase was found from X-ray diffraction in the gel samples to approx. 890 C. At higher temperatures, alpha quartz precipitated out as the crystalline phase in gels containing up to 10 mol % MgO. The overall activation energy for gel formation in 10MgO-90SiO2 (mol %) system for water/TEOS mole ratio of 7.5 was calculated to be 58.7 kJ/mol.

Sol-gel synthesis of magnesium oxide-silicon dioxide glass compositions

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.

1988-01-01

MgO-SiO2 glasses containing up to 15 mol pct MgO, which could not have been prepared by the conventional glass melting method due to the presence of stable liquid-liquid immiscibility, were synthesized by the sol-gel technique. Clear and transparent gels were obtained from the hydrolysis and polycondensation of silicon tetraethoxide (TEOS) and magnesium nitrate hexahydrate when the water/TEOS mole ratio was four or more. The gelling time decreased with increase in magnesium content, water/TEOS ratio, and reaction temperature. Magnesium nitrate hexahydrate crystallized out of the gels containing 15 and 20 mol pct MgO on slow drying. This problem was partially alleviated by drying the gels quickly at higher temperatures. Monolithic gel samples were prepared using glycerol as the drying control additive. The gels were subjected to various thermal treatments and characterized by several methods. No organic groups could be detected in the glasses after heat treatments to approx. 800 C, but trace amounts of hydroxyl groups were still present. No crystalline phase was found from X-ray diffraction in the gel samples to approx. 890 C. At higher temperatures, alpha quartz precipitated out as the crystalline phase in gels containing up to 10 mol pct MgO. The overall activation energy for gel formation in 10MgO-90SiO2 (mol pct) system for water/TEOS mole ratio of 7.5 was calculated to be 58.7 kJ/mol.

Redox-switchable copper(I) metallogel: a metal-organic material for selective and naked-eye sensing of picric acid.

PubMed

Sarkar, Sougata; Dutta, Soumen; Chakrabarti, Susmita; Bairi, Partha; Pal, Tarasankar

2014-05-14

Thiourea (TU), a commercially available laboratory chemical, has been discovered to introduce metallogelation when reacted with copper(II) chloride in aqueous medium. The chemistry involves the reduction of Cu(II) to Cu(I) with concomitant oxidation of thiourea to dithiobisformamidinium dichloride. The gel formation is triggered through metal-ligand complexation, i.e., Cu(I)-TU coordination and extensive hydrogen bonding interactions involving thiourea, the disulfide product, water, and chloride ions. Entangled network morphology of the gel selectively develops in water, maybe for its superior hydrogen-bonding ability, as accounted from Kamlet-Taft solvent parameters. Complete and systematic chemical analyses demonstrate the importance of both Cu(I) and chloride ions as the key ingredients in the metal-organic coordination gel framework. The gel is highly fluorescent. Again, exclusive presence of Cu(I) metal centers in the gel structure makes the gel redox-responsive and therefore it shows reversible gel-sol phase transition. However, the reversibility does not cause any morphological change in the gel phase. The gel practically exhibits its multiresponsive nature and therefore the influences of different probable interfering parameters (pH, selective metal ions and anions, selective complexing agents, etc.) have been studied mechanistically and the results might be promising for different applications. Finally, the gel material shows a highly selective visual response to a commonly used nitroexplosive, picric acid among a set of 19 congeners and the preferred selectivity has been mechanistically interpreted with density functional theory-based calculations.

Wetting and phase separation in soft adhesion

PubMed Central

Jensen, Katharine E.; Sarfati, Raphael; Style, Robert W.; Boltyanskiy, Rostislav; Chakrabarti, Aditi; Chaudhury, Manoj K.; Dufresne, Eric R.

2015-01-01

In the classic theory of solid adhesion, surface energy drives deformation to increase contact area whereas bulk elasticity opposes it. Recently, solid surface stress has been shown also to play an important role in opposing deformation of soft materials. This suggests that the contact line in soft adhesion should mimic that of a liquid droplet, with a contact angle determined by surface tensions. Consistent with this hypothesis, we observe a contact angle of a soft silicone substrate on rigid silica spheres that depends on the surface functionalization but not the sphere size. However, to satisfy this wetting condition without a divergent elastic stress, the gel phase separates from its solvent near the contact line. This creates a four-phase contact zone with two additional contact lines hidden below the surface of the substrate. Whereas the geometries of these contact lines are independent of the size of the sphere, the volume of the phase-separated region is not, but rather depends on the indentation volume. These results indicate that theories of adhesion of soft gels need to account for both the compressibility of the gel network and a nonzero surface stress between the gel and its solvent. PMID:26553989

Sol-gel transition of organogels observed by terahertz spectroscopy

NASA Astrophysics Data System (ADS)

Hoshina, Hiromichi; Ozaki, Atsumi; Itagaki, Yusuke; Yajima, Setsuko; Suzuki, Hal; Ishii, Shinya; Ishida, Misaki; Uchiyama, Tetsuji; Kimura, Keiichi; Otani, Chiko

2014-07-01

Terahertz (THz) absorption spectra of organogels consisting of (1R,2R)-1,2-bis(dodecanoylamino)cyclohexane/2-nitrophenyl octyl ether (RR-BDC/NPOE) and RR-BDC/n-dodecane were measured by Fourier-transform far-infrared (FT-FIR) spectroscopy. The vibrational peaks of the gels were observed at the same frequencies as those of the pure gelator, suggesting that the intermolecular structure around the Nsbnd H⋯Odbnd C hydrogen bond is maintained in the gel phase. Temperature-dependent spectroscopy showed a drastic spectral change at the sol-gel transition temperature, in which the vibrational peak at 3.5 THz disappears and a new peak appears at 2.9 THz. The change in THz vibrational frequency is indicative of the structural collapse of the hydrogen-bonded fibrous architecture in the sol phase.

Analysis of soybean tissue culture protein dynamics using difference gel electrophoresis.

PubMed

Miernyk, Ján A; Jett, Alissa A; Johnston, Mark L

2016-01-01

Excised hypocotyls from developing soybean (Glycine max (L.) merr. cv. Jack) were cultivated on agar-solidified medium until callus formed. The calli were then propagated in liquid medium until stable, relatively uniform, finely-divided suspension cultures were obtained. Cells were typically transferred to fresh medium at 7-day intervals. Cultures were harvested by filtration five days (early log phase) or eight days (late log phase) after transfer. In order to evaluate dynamic changes, both intracellular and extracellular proteins were analyzed by 2-dimensional difference gel electrophoresis. Selected spots were subjected to in-gel tryptic-digestion and the resultant peptides were analyzed by nLC-MS/MS. In follow-up studies gel-free shot-gun analyses led to identification of 367 intracellular proteins and 188 extracellular proteins. The significance of the described research is two-fold. First a gel-based proteomics method was applied to the study of the dynamics of the secretome (extracellular proteins). Second, results of a shot-gun non-gel based proteomic survey of both cellular and extracellular proteins are presented. Published by Elsevier B.V.

Efficacy of an ethanol/guar/triclosan/glycerine gel on bacteria and yeast loads in canine pododermatitis: a pilot study.

PubMed

Ortalda, C; Noli, C; Cena, T

2016-04-01

To assess efficacy of a gel compound containing guar, glycerine, triclosan and ethanol (Pawcare®, JOKER Technologies, Kerzers, Switzerland) in decreasing bacterial and yeast loads on the paws of dogs with erythematous, greasy and/or malodorous pododermatitis. In 20 dogs, each with at least two affected paws, semiquantitative Malassezia species counts were performed on 10 oil-immersion fields (range: 0 to 30) from acetate tapes pressed on the palmar/plantar surface of one paw. Half of the area was sampled before and the other half immediately after the application of Pawcare(®) . With a similar procedure, swab samples were collected from the other paw for bacterial culture, identification and evaluation of colony-forming units before and immediately after treatment. Statistical evaluation of pre- and posttreatment counts was performed with the Wilcoxon signed-rank test. Nine dogs were positive for Malassezia species Mean acetate tape preparation counts decreased significantly from 8·78 (±8·03) to 5·668 (±6·65) (P=0·0039) after treatment. Twenty-five bacterial isolates of 11 different species were cultured in 19 dogs. Posttreatment cultures were sterile in 8 dogs that had an initial zero or low number (1 to 2 log counts) of colony-forming units. In cases with a higher pre-treatment number of colony forming units (2 to 6 log counts), there was a significant decrease - by a mean of 1·16 log counts (pre 3·12 ±1·69, post 1·96 ±1·57) (P=0·0002). The findings of the present study support the use of PawCare® gel to decrease bacterial and yeast loads in dogs affected by chronic diseases involving the inter-digital spaces. © 2016 British Small Animal Veterinary Association.

Study Of Phase Separation In Glass

NASA Technical Reports Server (NTRS)

Neilson, George F.; Weinberg, Michael C.; Smith, Gary L.

1989-01-01

Report describes an experimental study of effect of hydroxide content on phase separation in soda/silica glasses. Ordinary and gel glasses melted at 1,565 degree C, and melts stirred periodically. "Wet" glasses produced by passing bubbles of N2 saturated with water through melts; "dry" glasses prepared in similar manner, except N2 dried before passage through melts. Analyses of compositions of glasses performed by atomic-absorption and index-of-refraction measurements. Authors conclude hydroxide speeds up phase separation, regardless of method (gel or ordinary) by which glass prepared. Eventually helps material scientists to find ways to control morphology of phase separation.

Optimizing Metalloporphyrin-Catalyzed Reduction Reactions for In Situ Remediation of DOE Contaminants

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

Schlautman, Mark A.

2013-07-14

Past activities have resulted in a legacy of contaminated soil and groundwater at Department of Energy facilities nationwide. Uranium and chromium are among the most frequently encountered and highest-priority metal and radionuclide contaminants at DOE installations. Abiotic chemical reduction of uranium and chromium at contaminated DOE sites can be beneficial because the reduced metal species are less soluble in water, less mobile in the environment, and less toxic to humans and ecosystems. Although direct biological reduction has been reported for U(VI) and Cr(VI) in laboratory studies and at some field sites, the reactions can sometimes be slow or even inhibitedmore » due to unfavorable environmental conditions. One promising approach for the in-situ remediation of DOE contaminants is to develop electron shuttle catalysts that can be delivered precisely to the specific subsurface locations where contaminants reside. Previous research has shown that reduction of oxidized organic and inorganic contaminants often can be catalyzed by electron shuttle systems. Metalloporphyrins and their derivatives are well known electron shuttles for many biogeochemical systems, and thus were selected to study their catalytic capabilities for the reduction of chromium and uranium in the presence of reducing agents. Zero valent iron (ZVI) was chosen as the primary electron donor in most experimental systems. Research proceeded in three phases and the key findings of each phase are reported here. Phase I examined Cr(VI) reduction and utilized micro- and nano-sized ZVI as the electron donors. Electron shuttle catalysts tested were cobalt- and iron-containing metalloporphyrins and Vitamin B12. To aid in the recycle and reuse of the nano-sized ZVI and soluble catalysts, sol-gels and calcium-alginate gel beads were tested as immobilization/support matrices. Although the nano-sized ZVI could be incorporated within the alginate gel beads, preliminary attempts to trap it in sol-gels were not successful. Conversely, the water-soluble catalysts could be trapped within sol-gel matrices but they tended to leach out of the alginate gel beads during use. In general, immobilization of the nano-sized ZVI in gel beads and of the catalysts in sol-gels tended to result in slower rates of Cr(VI) reduction, but these effects could be overcome to some extent by using higher reactant/catalyst concentrations. In addition, the lowering of their effectiveness would likely be offset by the benefits obtained when recycling and reusing the materials because they were immobilized. Addition of the catalytic electron shuttles will be most useful when the micro-sized or nano-sized ZVI becomes less reactive with reaction time. Continued work in Phase II in the area of nano-sized ZVI immobilization led to procedures that were successful in incorporating the iron particles in sol-gel matrices. The water-soluble reductants sodium dithionite and L-ascorbic acid were also tested, but their use appeared to lead to formation of complexes with the uranyl cation which limited their effectiveness. Also, although the sol-gel supported nano-sized ZVI showed some promise at reducing uranium, the fluoride used in the sol-gel synthesis protocol appeared to lead to formation of uranyl-fluoride complexes that were less reactive. Because hexavalent chromium is an anion which does not form complexes with fluoride, it was used to demonstrate the intrinsic reactivity of the sol-gel immobilized nano-sized ZVI. Consistent with our observations in Phase I, the sol-gel matrix once again slowed down the reduction reaction but the expected benefits of recycle/reuse should outweigh this adverse effect. The major emphasis in Phase III of this study was to simultaneously incorporate nano-sized ZVI and water-soluble catalysts in the same sol-gel matrix. The catalysts utilized were cobalt complexes of uroporphyrin and protoporphyrin and Cr(VI) reduction was used to test the efficacy of the combined "catalyst + reductant" sol-gel matrix. When enough catalyst was added to the sol-gels, enhancement of the Cr(VI) reduction reaction was observed. At the lowest levels of catalyst addition, however, the rates of Cr(VI) reduction were similar to those systems which only used sol-gel immobilized nano-sized ZVI without any catalyst present. These findings suggest future areas of research that should be pursued to further optimize abiotic reduction reactions of metals with combined "catalyst + reductant" matrices.« less

Pharmacokinetics of detomidine following intravenous or oral-transmucosal administration and sedative effects of the oral-transmucosal treatment in dogs.

PubMed

Messenger, Kristen M; Hopfensperger, Marie; Knych, Heather K; Papich, Mark G

2016-04-01

To determine the pharmacokinetics of detomidine hydrochloride administered IV (as an injectable formulation) or by the oral-transmucosal (OTM) route (as a gel) and assess sedative effects of the OTM treatment in healthy dogs. 12 healthy adult dogs. In phase 1, detomidine was administered by IV (0.5 mg/m(2)) or OTM (1 mg/m(2)) routes to 6 dogs. After a 24-hour washout period, each dog received the alternate treatment. Blood samples were collected for quantification via liquid chromatography with mass spectrometry and pharmacokinetic analysis. In phase 2, 6 dogs received dexmedetomidine IV (0.125 mg/m(2)) or detomidine gel by OTM administration (0.5 mg/m(2)), and sedation was measured by a blinded observer using 2 standardized sedation scales while dogs underwent jugular catheter placement. After a l-week washout period, each dog received the alternate treatment. Median maximum concentration, time to maximum concentration, and bioavailability for detomidine gel following OTM administration were 7.03 ng/mL, 1.00 hour, and 34.52%, respectively; harmonic mean elimination half-life was 0.63 hours. All dogs were sedated and became laterally recumbent with phase 1 treatments. In phase 2, median global sedation score following OTM administration of detomidine gel was significantly lower (indicating a lesser degree of sedation) than that following IV dexmedetomidine treatment; however, total sedation score during jugular vein catheterization did not differ between treatments. The gel was subjectively easy to administer, and systemic absorption was sufficient for sedation. Detomidine gel administered by the OTM route provided sedation suitable for a short, minimally invasive procedure in healthy dogs.

Morphological transitions of brain sphingomyelin are determined by the hydration protocol: ripples re-arrange in plane, and sponge-like networks disintegrate into small vesicles.

PubMed

Meyer, H W; Bunjes, H; Ulrich, A S

1999-06-01

The phase transition of hydrated brain sphingomyelin occurs at around 35 degrees C, which is close to the physiological temperature. Freeze-fracture electron microscopy is used to characterize different gel state morphologies in terms of solid-ordered and liquid-ordered phase states, according to the occurrence of ripples and other higher-dimensional bilayer deformations. Evidently, the natural mixed-chain sphingomyelin does not assume the flat L beta, phase but instead the rippled P beta, phase, with symmetric and asymmetric ripples as well as macroripples and an egg-carton pattern, depending on the incubation conditions. An unexpected difference was observed between samples that are hydrated above and below the phase transition temperature. When the lipid is hydrated at low temperature, a sponge-like network of bilayers is formed in the gel state, next to some normal lamellae. The network loses its ripples during cold-incubation, which indicates the formation of a liquid-ordered (lo) gel phase. Ripples re-appear upon warming and the sponge-like network disintegrates spontaneously and irreversibly into small vesicles above the phase transition.

Matrix molecularly imprinted mesoporous sol-gel sorbent for efficient solid-phase extraction of chloramphenicol from milk.

PubMed

Samanidou, Victoria; Kehagia, Maria; Kabir, Abuzar; Furton, Kenneth G

2016-03-31

Highly selective and efficient chloramphenicol imprinted sol-gel silica based inorganic polymeric sorbent (sol-gel MIP) was synthesized via matrix imprinting approach for the extraction of chloramphenicol in milk. Chloramphenicol was used as the template molecule, 3-aminopropyltriethoxysilane (3-APTES) and triethoxyphenylsilane (TEPS) as the functional precursors, tetramethyl orthosilicate (TMOS) as the cross-linker, isopropanol as the solvent/porogen, and HCl as the sol-gel catalyst. Non-imprinted sol-gel polymer (sol-gel NIP) was synthesized under identical conditions in absence of template molecules for comparison purpose. Both synthesized materials were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR) and nitrogen adsorption porosimetry, which unambiguously confirmed their significant structural and morphological differences. The synthesized MIP and NIP materials were evaluated as sorbents for molecularly imprinted solid phase extraction (MISPE) of chloramphenicol in milk. The effect of critical extraction parameters (flow rate, elution solvent, sample and eluent volume, selectivity coefficient, retention capacity) was studied in terms of retention and desorption of chloramphenicol. Competition and cross reactivity tests have proved that sol-gel MIP sorbent possesses significantly higher specific retention and enrichment capacity for chloramphenicol compared to its non-imprinted analogue. The maximum imprinting factor (IF) was found as 9.7, whereas the highest adsorption capacity of chloramphenicol by sol-gel MIP was 23 mg/g. The sol-gel MIP was found to be adequately selective towards chloramphenicol to provide the necessary minimum required performance limit (MRPL) of 0.3 μg/kg set forth by European Commission after analysis by LC-MS even without requiring time consuming solvent evaporation and sample reconstitution step, often considered as an integral part in solid phase extraction work-flow. Intra and inter-assay RSD values were less than 13% and accuracy expressed as relative recovery ranged from 85 to 106%. Copyright © 2016 Elsevier B.V. All rights reserved.

A novel low-molecular-mass gelator with a redox active ferrocenyl group: tuning gel formation by oxidation.

PubMed

Liu, Jing; Yan, Junlin; Yuan, Xuanwei; Liu, Kaiqiang; Peng, Junxia; Fang, Yu

2008-02-15

A novel low-molecular-mass gelator containing a redox-active ferrocenyl group, cholesteryl glycinate ferrocenoylamide (CGF), was intentionally designed and prepared. It was demonstrated that the gelator gels 13 out of the 45 solvents tested. Scanning electron microscopy (SEM) measurements revealed that the gelator self-assembled into different supramolecular network structures in different gels. Chemical oxidation of the ferrocenyl residue resulted in phase transition of the gel from gel state to solution state. FTIR and (1)H NMR spectroscopy studies revealed that hydrogen bonding between the gelator molecules in the gel was one of the main driving forces for the formation of the gels.

Piezoelectric energy harvester having planform-tapered interdigitated beams

DOEpatents

Kellogg, Rick A [Tijeras, NM; Sumali, Hartono [Albuquerque, NM

2011-05-24

Embodiments of energy harvesters have a plurality of piezoelectric planform-tapered, interdigitated cantilevered beams anchored to a common frame. The plurality of beams can be arranged as two or more sets of beams with each set sharing a common sense mass affixed to their free ends. Each set thus defined being capable of motion independent of any other set of beams. Each beam can comprise a unimorph or bimorph piezoelectric configuration bonded to a conductive or non-conductive supporting layer and provided with electrical contacts to the active piezoelectric elements for collecting strain induced charge (i.e. energy). The beams are planform tapered along the entirety or a portion of their length thereby increasing the effective stress level and power output of each piezoelectric element, and are interdigitated by sets to increase the power output per unit volume of a harvester thus produced.

A Theoretical Model of Jigsaw-Puzzle Pattern Formation by Plant Leaf Epidermal Cells.

PubMed

Higaki, Takumi; Kutsuna, Natsumaro; Akita, Kae; Takigawa-Imamura, Hisako; Yoshimura, Kenji; Miura, Takashi

2016-04-01

Plant leaf epidermal cells exhibit a jigsaw puzzle-like pattern that is generated by interdigitation of the cell wall during leaf development. The contribution of two ROP GTPases, ROP2 and ROP6, to the cytoskeletal dynamics that regulate epidermal cell wall interdigitation has already been examined; however, how interactions between these molecules result in pattern formation remains to be elucidated. Here, we propose a simple interface equation model that incorporates both the cell wall remodeling activity of ROP GTPases and the diffusible signaling molecules by which they are regulated. This model successfully reproduces pattern formation observed in vivo, and explains the counterintuitive experimental results of decreased cellulose production and increased thickness. Our model also reproduces the dynamics of three-way cell wall junctions. Therefore, this model provides a possible mechanism for cell wall interdigitation formation in vivo.

Reflection Spectra of Distorted Cholesteric Liquid Crystal Structures in Cells with Interdigitated Electrodes (Postprint)

DTIC Science & Technology

2014-07-01

adjusting the magnitude of the electric field. 15. SUBJECT TERMS liquid crystals , liquid- crystal devices, Bragg reflectors, optical properties, chiral ...160.3710) Liquid crystals ; (230.3720) Liquid- crystal devices; (230.1480) Bragg reflectors; (160.4760) Optical properties; (160.1585) Chiral media...White, and T. J. Bunning, “Local optical spectra and texture for chiral nematic liquid crystals in cells with interdigitated electrodes,” Mol

Therapeutic effectiveness of Ageratina pichinchensis on the treatment of chronic interdigital tinea pedis: a randomized, double-blind clinical trial.

PubMed

Romero-Cerecero, Ofelia; Zamilpa, Alejandro; Jiménez-Ferrer, Enrique; Tortoriello, Jaime

2012-06-01

Interdigital tinea pedis is the most frequent presentation, as well as the most severe clinical form of tinea pedis, constituting a therapeutic challenge. The aim of the study was to evaluate the effectiveness and tolerability of two concentrations of Ageratina pichinchensis extract (encecalin content, 0.76 and 1.52%, respectively) on patients with clinical and mycological diagnosis of chronic interdigital tinea pedis. By means of a randomized, double-blind clinical trial, three groups of patients were treated topically for 4 weeks with a cream containing the following: Group I-the lower concentration of A. pichinchensis extract, group II-the higher concentration, group III-2% ketoconazole. One hundred and sixty (160) ambulatory patients of either sex between the ages of 18 and 65 years were enrolled. The primary outcome variables were: clinical effectiveness, mycological effectiveness, therapeutic cure, tolerability, and treatment compliance. The secondary outcome variable was therapeutic success. At the end of treatment, therapeutic cure was achieved by 34.1, 41.8, and 39.53% of Groups I, II, and III, respectively. No statistical difference between the groups was observed. Both treatments were effective for the treatment of interdigital-type tinea pedis, while better results were observed on patients that received the higher concentration of the extract.

Meaning of visualizing retinal cone mosaic on adaptive optics images.

PubMed

Jacob, Julie; Paques, Michel; Krivosic, Valérie; Dupas, Bénédicte; Couturier, Aude; Kulcsar, Caroline; Tadayoni, Ramin; Massin, Pascale; Gaudric, Alain

2015-01-01

To explore the anatomic correlation of the retinal cone mosaic on adaptive optics images. Retrospective nonconsecutive observational case series. A retrospective review of the multimodal imaging charts of 6 patients with focal alteration of the cone mosaic on adaptive optics was performed. Retinal diseases included acute posterior multifocal placoid pigment epitheliopathy (n = 1), hydroxychloroquine retinopathy (n = 1), and macular telangiectasia type 2 (n = 4). High-resolution retinal images were obtained using a flood-illumination adaptive optics camera. Images were recorded using standard imaging modalities: color and red-free fundus camera photography; infrared reflectance scanning laser ophthalmoscopy, fluorescein angiography, indocyanine green angiography, and spectral-domain optical coherence tomography (OCT) images. On OCT, in the marginal zone of the lesions, a disappearance of the interdigitation zone was observed, while the ellipsoid zone was preserved. Image recording demonstrated that such attenuation of the interdigitation zone co-localized with the disappearance of the cone mosaic on adaptive optics images. In 1 case, the restoration of the interdigitation zone paralleled that of the cone mosaic after a 2-month follow-up. Our results suggest that the interdigitation zone could contribute substantially to the reflectance of the cone photoreceptor mosaic. The absence of cones on adaptive optics images does not necessarily mean photoreceptor cell death. Copyright © 2015 Elsevier Inc. All rights reserved.

The microwave properties of Ag(Ta0.8Nb0.2)O3 thick film interdigital capacitors on alumina substrates

NASA Astrophysics Data System (ADS)

Lee, Ku-Tak; Koh, Jung-Hyuk

2012-01-01

In this paper, we will introduce the microwave properties of Ag(Ta0.8Nb0.2)O3 thick film planar type interdigital capacitors fabricated on alumina substrates. The tailored paraelectric state of Ag(Ta,Nb)O3 allows the material to be regarded as a part of the family of microwave materials. As thick films formed in our experiment, Ag(Ta,Nb)O3 exhibited extremely low dielectric loss with relatively high dielectric permittivity. This low dielectric loss is a very important issue for microwave applications. Therefore, we investigated the microwave properties of Ag(Ta0.8Nb0.2)O3 thick film planar type interdigital capacitors. Ag(Ta0.8Nb0.2)O3 thick films were prepared by a screen-printing method on alumina substrates and were sintered at 1140 °C for 2 hrs. The XRD analysis results showed that the Ag(Ta0.8Nb0.2)O3 thick film has the perovskite structure. The frequency dependent dielectric permittivity showed that these Ag(Ta0.8Nb0.2)O3 thick film planar type interdigital capacitors have very weak frequency dispersions with low loss tangents in the microwave range.

Thermally Induced Lateral Motion of α-Zirconium Phosphate Layers Intercalated with Hexadecylamines

NASA Astrophysics Data System (ADS)

Char, Kookheon

2005-03-01

Well-defined intercalated structure, either interdigitated layers or bilayers, of hexadecylamines (HDAs) in a confined space of a highly-functionalized layered material, α- zirconium phosphate (α-ZrP), was prepared and these two distinct intercalated structures can serve as model systems to investigate the interaction of the two monolayers whose amphiphilic tails are adjacent to each other. Acidic functional groups (-POH) on the α-ZrP are in well-ordered array and the number of functional group is quite high (i.e., cationic exchange capacity (CEC) = 664 mmole/100 g, area per one charge site = 0.24 nm^2) enough to realize the bilayers (i.e., discrete two monolayers) of HDAs within the α-ZrP interlayer. We employed the two-step intercalation mechanism for the preparation of well- ordered interdigitated layers as well as the bilayers of alkyl chains attached to both sides of the α-ZrP intergallery. An intriguing lateral motion of the α-ZrP sheets was observed with in-situ SAXS measurements for the interdigitated layer during heating and cooling cycle and verified with TEM. This lateral motion is believed to be due to the transition from the tilted to the untilted conformation of the interdigitated HDA chains and this transition is found to be thermally reversible.

Highly porous solid-phase microextraction fiber coating based on poly(ethylene glycol)-modified ormosils synthesized by sol-gel technology.

PubMed

da Costa Silva, Raquel Gomes; Augusto, Fabio

2005-04-22

The preparation and characteristics of solid-phase microextraction (SPME) fibers coated with Carbowax 20M ormosil (organically modified silica) are described here. Raw fused silica fibers were coated with Carbowax 20M-modified silica using sol-gel process. Scanning electron micrographs of fibers revealed a highly porous, sponge-like coating with an average thickness of (8 +/- 1) microm. The sol-gel Carbowax fibers were compared to commercial fibers coated with 100 microm polydimethylsiloxane (PDMS) and 65 microm Carbowax-divinylbenzene (DVB). Shorter equilibrium times were possible with the sol-gel Carbowax fiber: for headspace extraction of the test analytes, they ranged from less than 3 min for benzene to 15 min for o-xylene. Extraction efficiencies of the sol-gel Carbowax fiber were superior to those of conventional fibers: for o-xylene, the extracted masses were 230 and 540% of that obtained with 100 microm PDMS and 65 microm Carbowax-DVB fibers, respectively.

A π-gel scaffold for assembling fullerene to photoconducting supramolecular rods

PubMed Central

Nair, Vishnu Sukumaran; Mukhopadhyay, Rahul Dev; Saeki, Akinori; Seki, Shu; Ajayaghosh, Ayyappanpillai

2016-01-01

Nonequilibrium self-assembly of molecules holds a huge prospect as a tool for obtaining new-generation materials for future applications. Crystallization of neutral molecules within a supramolecular gel matrix is one example in which two nonequilibrium processes occur orthogonal to each other. On the other hand, electronically interacting donor-acceptor two-component systems are expected to form phase-miscible hybrid systems. Contrary to the expectation, we report the behavior of a π-gel, derived from oligo(p-phenylenevinylene), OPVA, as a scaffold for the phase separation and crystallization of fullerene (C60) to supramolecular rods with increased transient photoconductivity (φƩμmax = 2.4 × 10−4 cm2 V−1 s−1). The C60 supramolecular rods in the π-gel medium exhibited high photocurrent in comparison to C60 loaded in a non–π-gel medium. This finding provides an opportunity for large-scale preparation of micrometer-sized photoconducting rods of fullerenes for device application. PMID:27679815

Separation of pharmacologically active nitrogen-containing compounds on silica gels modified with 6,10-ionene, dextran sulfate, and gold nanoparticles

NASA Astrophysics Data System (ADS)

Ioutsi, A. N.; Shapovalova, E. N.; Ioutsi, V. A.; Mazhuga, A. G.; Shpigun, O. A.

2017-12-01

New stationary phases for HPLC are obtained via layer-by-layer deposition of polyelectrolytes and studied: (1) silica gel modified layer-by-layer with 6,10-ionene and dextran sulfate (Sorbent 1); (2) silica gel twice subjected to the above modification (Sorbent 2); and (3) silica gel modified with 6,10-ionene, gold nanoparticles, and dextran sulfate (Sorbent 3). The effect the content of the organic solvent in the mobile phase and the concentration and pH of the buffer solution have on the chromatographic behavior of several pharmacologically active nitrogen-containing compounds is studied. The sorbents are stable during the process and allow the effective separation of beta-blockers, calcium channel blockers, alpha-agonists, and antihistamines. A mixture of caffeine, nadolol, tetrahydrozoline, pindolol, orphenadrine, doxylamine, carbinoxamine, and chlorphenamine is separated in 6.5 min on the silica gel modified with 6,10-ionene, gold nanoparticles, and dextran sulfate.

Characterization of Fe-doped SrTiO3/BaTiO3 multilayer films and their ethanol sensing applications

NASA Astrophysics Data System (ADS)

Supasai, Thidarat; Wisitsoraat, Anurat; Hodak, Satreerat

2010-03-01

Fe-doped SrTiO3/BaTiO3 multilayer films have been deposited on alumina substrate using a sol-gel spin coating technique. The field effect scanning electron microscope photographs revealed a mixture of round and facet-shaped crystals in the undoped films. This microstructure disappeared in Fe-doped films which adopted a more porous sponge-like structure. The grain size of the films decreased from 300 nm for undoped films to 100 nm and 70 nm with Fe doping concentrations of 4 and 8 wt%, respectively. The absorption edge energy for X-rays by Fe was found to be about 7121 eV consistent with Fe^2+ oxidation state. Interdigitated electrodes were applied on these films for ethanol gas sensing application. A sensitivity figure of merit based on the relative change in the resistance of the Fe-doped films 8 wt% film was found to be in the 1-3 range for ethanol doses of 100-1000 ppm when operating at 250 C and in the range of 3-10 when the operating temperature was 350 C.

Comprehensive multiphase NMR spectroscopy: Basic experimental approaches to differentiate phases in heterogeneous samples

NASA Astrophysics Data System (ADS)

Courtier-Murias, Denis; Farooq, Hashim; Masoom, Hussain; Botana, Adolfo; Soong, Ronald; Longstaffe, James G.; Simpson, Myrna J.; Maas, Werner E.; Fey, Michael; Andrew, Brian; Struppe, Jochem; Hutchins, Howard; Krishnamurthy, Sridevi; Kumar, Rajeev; Monette, Martine; Stronks, Henry J.; Hume, Alan; Simpson, André J.

2012-04-01

Heterogeneous samples, such as soils, sediments, plants, tissues, foods and organisms, often contain liquid-, gel- and solid-like phases and it is the synergism between these phases that determine their environmental and biological properties. Studying each phase separately can perturb the sample, removing important structural information such as chemical interactions at the gel-solid interface, kinetics across boundaries and conformation in the natural state. In order to overcome these limitations a Comprehensive Multiphase-Nuclear Magnetic Resonance (CMP-NMR) probe has been developed, and is introduced here, that permits all bonds in all phases to be studied and differentiated in whole unaltered natural samples. The CMP-NMR probe is built with high power circuitry, Magic Angle Spinning (MAS), is fitted with a lock channel, pulse field gradients, and is fully susceptibility matched. Consequently, this novel NMR probe has to cover all HR-MAS aspects without compromising power handling to permit the full range of solution-, gel- and solid-state experiments available today. Using this technology, both structures and interactions can be studied independently in each phase as well as transfer/interactions between phases within a heterogeneous sample. This paper outlines some basic experimental approaches using a model heterogeneous multiphase sample containing liquid-, gel- and solid-like components in water, yielding separate 1H and 13C spectra for the different phases. In addition, 19F performance is also addressed. To illustrate the capability of 19F NMR soil samples, containing two different contaminants, are used, demonstrating a preliminary, but real-world application of this technology. This novel NMR approach possesses a great potential for the in situ study of natural samples in their native state.

Comprehensive multiphase NMR spectroscopy: basic experimental approaches to differentiate phases in heterogeneous samples.

PubMed

Courtier-Murias, Denis; Farooq, Hashim; Masoom, Hussain; Botana, Adolfo; Soong, Ronald; Longstaffe, James G; Simpson, Myrna J; Maas, Werner E; Fey, Michael; Andrew, Brian; Struppe, Jochem; Hutchins, Howard; Krishnamurthy, Sridevi; Kumar, Rajeev; Monette, Martine; Stronks, Henry J; Hume, Alan; Simpson, André J

2012-04-01

Heterogeneous samples, such as soils, sediments, plants, tissues, foods and organisms, often contain liquid-, gel- and solid-like phases and it is the synergism between these phases that determine their environmental and biological properties. Studying each phase separately can perturb the sample, removing important structural information such as chemical interactions at the gel-solid interface, kinetics across boundaries and conformation in the natural state. In order to overcome these limitations a Comprehensive Multiphase-Nuclear Magnetic Resonance (CMP-NMR) probe has been developed, and is introduced here, that permits all bonds in all phases to be studied and differentiated in whole unaltered natural samples. The CMP-NMR probe is built with high power circuitry, Magic Angle Spinning (MAS), is fitted with a lock channel, pulse field gradients, and is fully susceptibility matched. Consequently, this novel NMR probe has to cover all HR-MAS aspects without compromising power handling to permit the full range of solution-, gel- and solid-state experiments available today. Using this technology, both structures and interactions can be studied independently in each phase as well as transfer/interactions between phases within a heterogeneous sample. This paper outlines some basic experimental approaches using a model heterogeneous multiphase sample containing liquid-, gel- and solid-like components in water, yielding separate (1)H and (13)C spectra for the different phases. In addition, (19)F performance is also addressed. To illustrate the capability of (19)F NMR soil samples, containing two different contaminants, are used, demonstrating a preliminary, but real-world application of this technology. This novel NMR approach possesses a great potential for the in situ study of natural samples in their native state. Copyright © 2012 Elsevier Inc. All rights reserved.

In vitro activity of Aloe vera inner gel against microorganisms grown in planktonic and sessile phases.

PubMed

Cataldi, V; Di Bartolomeo, S; Di Campli, E; Nostro, A; Cellini, L; Di Giulio, M

2015-12-01

The failure of traditional antimicrobial treatments is becoming a worldwide problem. The use of Aloe vera is of particular interest for its role as curative agent and its efficacy in complementary therapies for a variety of illnesses. This study evaluated the antimicrobial activity of A. vera inner gel against a panel of microorganisms, Gram-positive and -negative bacteria, and Candida albicans. In addition to A. vera inner gel being used in the treatment of peptic ulcers, in dermatological treatments, and wound healing, it was also tested on the sessile phase of clinical Helicobacter pylori strains (including multi-drug-resistant strains) and on planktonic and sessile phase of Staphylococcus aureus/Pseudomonas aeruginosa clinical isolates from venous leg ulcers.A. vera inner gel expresses its prevalent activity against Gram-negative bacteria and C. albicans in respect to Gram-positive bacteria. The results of the A. vera antibiofilm activity showed a decrease of the produced biomass in a concentration-dependent-way, in each analyzed microorganism. The data obtained show that A. vera inner gel has both an antimicrobial and antibiofilm activity suggesting its potential use for the treatment of microbial infections, in particular for H. pylori gastric infection, especially in case of multi-drug-resistance, as well as for an effective wound dressing. © The Author(s) 2015.

Mounting Pressure in the Microenvironment: Fluids, Solids, and Cells in Pancreatic Ductal Adenocarcinoma.

PubMed

DuFort, Christopher C; DelGiorno, Kathleen E; Hingorani, Sunil R

2016-06-01

The microenvironment influences the pathogenesis of solid tumors and plays an outsized role in some. Our understanding of the stromal response to cancers, particularly pancreatic ductal adenocarcinoma, has evolved from that of host defense to tumor offense. We know that most, although not all, of the factors and processes in the microenvironment support tumor epithelial cells. This reappraisal of the roles of stromal elements has also revealed potential vulnerabilities and therapeutic opportunities to exploit. The high concentration in the stroma of the glycosaminoglycan hyaluronan, together with the large gel-fluid phase and pressures it generates, were recently identified as primary sources of treatment resistance in pancreas cancer. Whereas the relatively minor role of free interstitial fluid in the fluid mechanics and perfusion of tumors has been long appreciated, the less mobile, gel-fluid phase has been largely ignored for historical and technical reasons. The inability of classic methods of fluid pressure measurement to capture the gel-fluid phase, together with a dependence on xenograft and allograft systems that inaccurately model tumor vascular biology, has led to an undue emphasis on the role of free fluid in impeding perfusion and drug delivery and an almost complete oversight of the predominant role of the gel-fluid phase. We propose that a hyaluronan-rich, relatively immobile gel-fluid phase induces vascular collapse and hypoperfusion as a primary mechanism of treatment resistance in pancreas cancers. Similar properties may be operant in other solid tumors as well, so revisiting and characterizing fluid mechanics with modern techniques in other autochthonous cancers may be warranted. Copyright © 2016 AGA Institute. Published by Elsevier Inc. All rights reserved.

Efficacy and cost-effectiveness of octenidine wound gel in the treatment of chronic venous leg ulcers in comparison to modern wound dressings.

PubMed

Hämmerle, Gilbert; Strohal, Robert

2016-04-01

The aim of this study was to determine the efficacy, safety and cost-effectiveness of an octenidine-based wound gel in the treatment of chronic venous leg ulcers. For this purpose, 49 wounds were treated with either modern wound-phase-adapted dressings alone (treatment arm 1; n = 17), octenidine wound gel plus modern wound-phase-adapted dressings (treatment arm 2; n = 17) or octenidine wound gel alone (treatment arm 3; n = 15). During the study period of 42 days with dressing changes every 3-5 days, wound healing characteristics and treatment costs of different dressings were analysed. Wound size reduction was significantly better (P = 0·028) in both octenidine wound gel treatment arms compared to modern dressings alone with total reductions of 14·6%, 64·1% and 96·2% in treatment arms 1-3. Early wound healing was merely observed under octenidine wound gel treatment (n = 9), whereby lowest treatment costs were generated by octenidine wound gel alone (€20·34/dressing change). As a result, the octenidine wound gel is cost-effective and well suitable for the treatment of chronic venous leg ulcers, considering both safety and promotion of wound healing. © 2014 The Authors. International Wound Journal © 2014 Medicalhelplines.com Inc and John Wiley & Sons Ltd.

Ultrasound-induced oscillations of gas bubbles in contact with gelatin gel surfaces

NASA Astrophysics Data System (ADS)

Fukui, Sosuke; Ando, Keita

2017-11-01

Ultrasound-induced dynamics of gas bubbles in the vicinity of deformable boundaries are studied experimentally, as a simplified model of sonoporation in medicine. In our experiment, 28-kHz underwater ultrasound was irradiated to a gas bubble nuclei (of radius from 60 μm to 200 μm) sitting at gel surfaces (of gelatin concentration from 6 wt% to 16 wt%) and the bubble dynamics were recorded by a high-speed camera. The repeated deformation of the gel surface was found to be in phase with volumetric oscillation of the bubble. A liquid jet, which can appear toward the collapse phase in the bubble oscillation in volume, produced localized surface deformation, which is an important observation in the context of sonoporation. We characterize the maximum displacement of the gel surface with varying the bubble nuclei radius (in comparison to the resonant radius fixed approximately at 117 μm). We also examine the phase difference between the ultrasound and the bubble dynamics under the influence of the deformable boundary. The Research Grant of Keio Leading-edge Laboratory of Science & Technology.

The incorporation of calix[6]arene and cyclodextrin derivatives into sol-gels for the preparation of stationary phases for gas chromatography.

PubMed

Delahousse, Guillaume; Peulon-Agasse, Valérie; Debray, Jean-Christophe; Vaccaro, Marie; Cravotto, Giancarlo; Jabin, Ivan; Cardinael, Pascal

2013-11-29

New polyethylene-glycol-based sol-gels containing cyclodextrin or calix[6]arene derivatives have been synthesized. An original method for sol-gel preparation and capillary column coating, which consumes smaller quantities of selectors and allows for control of their amounts in the stationary phase, is reported herein. The new stationary phases exhibited excellent column efficiencies over a large range of temperatures and thermal stability up to 280°C. The cyclodextrin derivative generally showed the best separation factors for aromatic positional isomers. The calix[6]arene derivative exhibited the best selectivity for the polychlorobiphenyl congeners and some polycyclic aromatic hydrocarbon isomers. The relationship between the structure and the chromatographic properties of the selectors is discussed. The tert-butyl groups on the upper rim of the calix[6]arene were found to possibly play an important role in the recognition of solutes. The incorporation of the cyclodextrin derivative into the sol-gel matrix did not affect its enantioselective recognition capabilities. Copyright © 2013 Elsevier B.V. All rights reserved.

Effects of sol-gel processing parameters on the phases and microstructures of HA films.

PubMed

Wang, Diangang; Chen, Chuanzhong; Liu, Xiuna; Lei, Tingquan

2007-06-15

Bioactive hydroxyapatite (HA) films were fabricated by a sol-gel method and triethylphosphate and calcium nitrate were used as the phosphorus and calcium precursors, respectively. The effects of the heat treatment temperature, pH level and substrate materials on the phases and microstructures of HA films were studied by X-ray diffraction (XRD), scanning electronic microscopy (SEM) and electronic probe microanalysis (EPMA) and so on. The results show that all the sol-gel films are composed of the phases of HA, CaO, TiO(2) and CaTiO(3). With increasing the calcining temperature, the crystallinity of the films increases, the structure becomes more compact and changes from granular and lamellar to cellular structure, and the Ca/P ratio increases slightly because of the loss of P in the films. The addition of ammonia (adjusting the pH level to be about 7.5) can increase the HA content in the films, and the difference of substrate materials only has a little influence on the microstructure of the sol-gel films.

Regenerated silica gel as stationary phase on vacuum column chromatography to purify temulawak's extracts

NASA Astrophysics Data System (ADS)

Cahyono, Bambang; Maduwu, Ratna Dewi; Widayat, Suzery, Meiny

2015-12-01

Commercial silica gel only used once by many researchers and affected high cost for purification process, also less support the green chemistry program. This research focused in regeneration silica gel that used purification of temulawak's extracts (Curcuma xanthorrhiza Roxb) by vacuum column chromatography. Sample extracts (contains 10.1195±0.5971% of curcuminoids) was purified by vacuum column chromatography (pressure: 45 kPa, column: 100mm on length and 16mm on diameter). Ethanol 96% and acetone were compared as eluent. The amount of solvent and yield of curcuminoids used as indicator purification. The silica gel was regenerated with heating in 600°C for 8 hours The silica gels were analyzed by IR spectroscopy and X-ray diffraction. Furthermore, regenerated silica gel was used as the stationary phase in vacuum column chromatography under the same conditions with the previous purification. All the purification experiments were performed in three repetitions. Based on regression equation, y=0.132x+0.0011 (r2=0.9997) the yield of curcuminoids on purified products using ethanol as the eluent was improved 4.26% (to 14.3724±0.5749%) and by acetone was improved 3,03% (to 13.1450 ±0.6318%). The IR spectrum of both silica gel showed the same vibration profile and also there were three crystallinity peaks missing on its X-ray diffraction. Regenerated silica gel has the same performance with new silica gel in purification of temulawak's extract: by ethanol has increased 4.08% (14.1947±0.7415%) and 2.93% (13.0447±0.4822) by acetone. In addition, all purification products showed similar TLC profiles. Purification using regenerated silica gel as the adsorbent on vacuum column chromatography has exactly same potential with the new silica gel.

Synthesis of LiCoO 2 thin films by sol/gel process

NASA Astrophysics Data System (ADS)

Porthault, H.; Le Cras, F.; Franger, S.

LiCoO 2 thin films were synthesized by sol/gel process using acrylic acid (AA) as chelating agent. The gel formulation was optimized by varying solvent (ethylene glycol or water) and precursors molar ratios (Li, Co, AA) in order to obtain a dense film for positive electrode of lithium batteries. The gel was deposited by spin-coating technique on an Au/TiO 2/SiN/SiO 2/Si substrate. Thin films were deposited by either single or multistep process to enhance the density of the thin film and then calcined during 5 h at 800 °C to obtain the R-3m phase (HT-LiCoO 2). A chemical characterization of the solution was realized by Fourier Transform Infrared (FTIR) spectroscopy. Thermal decomposition of precursors and gel was studied by Thermo Gravimetric Analyses (TGA). Further investigations were done to characterize rheologic behaviour of the gel and solvents affinity with the substrate. Crystallinity and morphology were analyzed respectively by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The formation of R-3m phase was confirmed by the electrochemical behaviour of the gel derived LiCoO 2. Cyclic voltammograms and galvanostatic cycling show typical curve shape of the HT-LiCoO 2.

Phase diagram of a reentrant gel of patchy particles

NASA Astrophysics Data System (ADS)

Roldán-Vargas, Sándalo; Smallenburg, Frank; Kob, Walter; Sciortino, Francesco

2013-12-01

We study the phase diagram of a binary mixture of patchy particles which has been designed to form a reversible gel. For this we perform Monte Carlo and molecular dynamics simulations to investigate the thermodynamics of such a system and compare our numerical results with predictions based on the analytical parameter-free Wertheim theory. We explore a wide range of the temperature-density-composition space that defines the three-dimensional phase diagram of the system. As a result, we delimit the region of thermodynamic stability of the fluid. We find that for a large region of the phase diagram the Wertheim theory is able to give a quantitative description of the system. For higher densities, our simulations show that the system is crystallizing into a BCC structure. Finally, we study the relaxation dynamics of the system by means of the density and temperature dependences of the diffusion coefficient. We show that there exists a density range where the system passes reversibly from a gel to a fluid upon both heating and cooling, encountering neither demixing nor phase separation.

Rectal Microbicide Development

PubMed Central

Dezzutti, Charlene

2014-01-01

The last few years have seen important progress in demonstrating the efficacy of oral pre-exposure prophylaxis, vaginal microbicides, and treatment as prevention as effective strategies for reducing the risk of acquiring or transmitting HIV infection. There has also been significant progress in the development of rectal microbicides. Preclinical non-human primate studies have demonstrated that antiretroviral microbicides can provide significant protection from rectal challenge with SIV or SHIV. Recent Phase 1 rectal microbicide studies have characterized the safety, acceptability, compartmental pharmacokinetics (PK), and pharmaco-dynamics (PD) of both UC781 and tenofovir gels. The tenofovir gel formulation used in vaginal studies was not well tolerated in the rectum and newer rectal-specific formulations have been developed and evaluated in Phase 1 studies. The PK/PD data generated in these Phase 1 studies may reduce the risk of advancing ineffective candidate rectal microbicides into late stage development. Tenofovir gel is currently poised to move into Phase 2 evaluation and it is possible that a Phase 2B/3 effectiveness study with this product could be initiated in the next 2–3 years. PMID:23612991

Ozone sensing based on palladium decorated carbon nanotubes.

PubMed

Colindres, Selene Capula; Aguir, Khalifa; Cervantes Sodi, Felipe; Vargas, Luis Villa; Salazar, José Moncayo; Febles, Vicente Garibay

2014-04-14

Multiwall carbon nanotubes (MWCNTs) were easily and efficiently decorated with Pd nanoparticles through a vapor-phase impregnation-decomposition method starting from palladium acetylacetonates. The sensor device consisted on a film of sensitive material (MWCNTs-Pd) deposited by drop coating on platinum interdigitated electrodes on a SiO₂ substrate. The sensor exhibited a resistance change to ozone (O₃) with a response time of 60 s at different temperatures and the capability of detecting concentrations up to 20 ppb. The sensor shows the best response when exposed to O3 at 120 °C. The device shows a very reproducible sensor performance, with high repeatability, full recovery and efficient response.

On crystal versus fiber formation in dipeptide hydrogelator systems.

PubMed

Houton, Kelly A; Morris, Kyle L; Chen, Lin; Schmidtmann, Marc; Jones, James T A; Serpell, Louise C; Lloyd, Gareth O; Adams, Dave J

2012-06-26

Naphthalene dipeptides have been shown to be useful low-molecular-weight gelators. Here we have used a library to explore the relationship between the dipeptide sequence and the hydrogelation efficiency. A number of the naphthalene dipeptides are crystallizable from water, enabling us to investigate the comparison between the gel/fiber phase and the crystal phase. We succeeded in crystallizing one example directly from the gel phase. Using X-ray crystallography, molecular modeling, and X-ray fiber diffraction, we show that the molecular packing of this crystal structure differs from the structure of the gel/fiber phase. Although the crystal structures may provide important insights into stabilizing interactions, our analysis indicates a rearrangement of structural packing within the fibers. These observations are consistent with the fibrillar interactions and interatomic separations promoting 1D assembly whereas in the crystals the peptides are aligned along multiple axes, allowing 3D growth. This observation has an impact on the use of crystal structures to determine supramolecular synthons for gelators.

Stability conditions and mechanism of cream soaps: role of glycerol.

PubMed

Sagitani, Hiromichi

2014-01-01

Fatty acids, fatty acid potassium soaps, glycerol and water are essential ingredients in the production of stable cream soaps. In this study, the behavior of these components in solution was investigated to elucidate the stability conditions and mechanism of cream soaps. It was determined that the cream soaps were a dispersion of 1:1 acid soap (1:1 molar ratio of potassium soap/fatty acid) crystals in the lamellar gel phase, which has confirmed from the phase behavior diagrams and small angle X-ray scattering data. Glycerol was crucial ingredient in the formation of the lamellar gel phase. The cleansing process of the cream soaps was also evaluated using the same diagrams. The structure of the continuous phase in cream soaps changed from lamellar gel to a micellar aqueous solution upon the addition of water. This structural change during the washing process is important in producing the foaming activity of acid soaps to wash away dirt or excess fats from the skin surface.

Investigations on gel forming media use in low gravity bioseparations research

NASA Technical Reports Server (NTRS)

Todd, Paul; Szlag, David C.; Plank, Lindsay D.; Delcourt, Scott G.; Kunze, M. Elaine

1989-01-01

Research on gelling media and conditions suitable for the preservation of the spatial configuration of cell suspensions and macromolecular solutions after separation in free fluid during low gravity experiments is presented. The examples studied included free electrophoresis of cells in a cylindrical column and two-phase aqueous polymer separation. Microgravity electrophoresis experiments were simulated by separating model cell types (animal or human) in a vertical density gradient containing low-conductivity buffer, 1.7-6.5 percent Ficoll, 6.8-5.0 percent sucrose, and 1 percent SeaPrep low-melting temperature agarose. Upon cooling, a gel formed in the column and cells could be captured at the forming locations. Two-phase extraction experiments were simulated using two-polymer solutions in which phase separation occurs in normal saline at temperatures compatible with cell viability and in which one or both phases form a gel upon cooling. Suitable polymers included commercial agaroses (1-2 percent), maltodextrin (5-7 percent), and gelatin (5-20 percent).

Cation-containing lipid membranes – experiment and md simulations

DOE PAGES

Kučerka, Norbert; Dushanov, Ermuhammas; Kholmurodov, Kholmirzo T.; ...

2017-11-27

Here, using small angle neutron diffraction and molecular dynamics simulations we studied the interactions between calcium (Ca 2+) or zinc (Zn 2+) cations, and oriented gel phase dipalmitoyl-phosphatidylcholine (DPPC) bilayers. For both cations studied at ~1:7 divalent metal ion to lipid molar ratio (Me2+:DPPC), bilayer thickness increased. Simulation results helped reveal subtle differences in the effects of the two cations on gel phase membranes.

Article for thermal energy storage

DOEpatents

Salyer, Ival O.

2000-06-27

A thermal energy storage composition is provided which is in the form of a gel. The composition includes a phase change material and silica particles, where the phase change material may comprise a linear alkyl hydrocarbon, water/urea, or water. The thermal energy storage composition has a high thermal conductivity, high thermal energy storage, and may be used in a variety of applications such as in thermal shipping containers and gel packs.

In situ observation of sol-gel transition of agarose aqueous solution by fluorescence measurement.

PubMed

Wang, Zheng; Yang, Kun; Li, Haining; Yuan, Chaosheng; Zhu, Xiang; Huang, Haijun; Wang, Yongqiang; Su, Lei; Fang, Yapeng

2018-06-01

Sol-gel transition behavior of agarose aqueous solution was investigated by using rheology and fluorescence measurement. On heating, the storage modulus G' decreased gradually, then deviated abruptly at the temperature of about 65°C, and finally decreased slowly again. For fluorescence measurement, the phase transition point kept almost at the temperature of 65°C, which was consistent with that in rheology measurement. Upon compression, it was indicated that the fluorescence lifetime for the probe in the agarose aqueous solution showed a dramatic change in the vicinity of the phase transition point. T vs. P phase diagram of agarose aqueous solution was constructed, which showed that the melting point was an increasing function of pressure. Based on the phase diagram, the agarose gels were prepared by cooling under atmospheric pressure and the pressure of 300MPa, respectively. From the result of the recovered samples studied by optical rheometry, it was found that agarose gel prepared under high pressure had a higher elasticity and lower viscosity index, compared with that under atmospheric pressure. It could be speculated that such kinds of properties might be attributed to the smaller pore size during gelation under high pressure. Copyright © 2018. Published by Elsevier B.V.

Comparison between two forms of vaginally administered progesterone for luteal phase support in assisted reproduction cycles.

PubMed

Geber, Selmo; Moreira, Ana Carolina Ferreira; de Paula, Sálua Oliveira Calil; Sampaio, Marcos

2007-02-01

The use of progesterone for luteal phase support has been demonstrated to be beneficial in assisted reproduction cycles using gonadotrophin-releasing hormone analogues (GnRHa). Two micronized progesterone preparations are available for vaginal administration: capsules and gel. The objective of this study was to compare the efficacy of these two forms for luteal phase support in assisted reproduction cycles. A total of 244 couples undergoing IVF/intracytoplasmic sperm injection cycles were included in the study and were randomly allocated (sealed envelopes) into two groups: group 1 (122) received vaginal capsules of 200 mg of micronized progesterone (Utrogestan), 3 times daily, and group 2 (122) received micronized progesterone in gel (Crinone 8%), once daily. Both groups received progesterone for 13 days beginning day 1 after oocyte retrieval, continuing until the pregnancy test was performed and until 12 weeks of pregnancy. Groups were compared by clinical data and assisted reproduction results and had similar ages and causes of infertility. Although the pregnancy rate was higher for those receiving progesterone gel than capsules (44.26 and 36.06% respectively), this difference was not statistically significant. The study showed that vaginal progesterone gel and capsules used for luteal phase support in assisted reproduction cycles with long protocol GnRHa result in similar pregnancy rates.

Techniques for the design and simulation of interdigitated MSM photodetectors

NASA Astrophysics Data System (ADS)

Cahill, Laurence W.

1997-04-01

The metal-semiconductor (MSM) photodetector attracts a great deal of interest as a result of its high bandwidth and low fabrication costs. In this paper a broad-band circuit model for the interdigitated MSM photodetector is presented. The circuit model can be used for both design and simulation purposes. The circuit model can also take into account nonlinear effects so that the practical behavior of the photodetector can be more faithfully represented.

A Theoretical Model of Jigsaw-Puzzle Pattern Formation by Plant Leaf Epidermal Cells

PubMed Central

Higaki, Takumi; Kutsuna, Natsumaro; Akita, Kae; Takigawa-Imamura, Hisako; Yoshimura, Kenji; Miura, Takashi

2016-01-01

Plant leaf epidermal cells exhibit a jigsaw puzzle–like pattern that is generated by interdigitation of the cell wall during leaf development. The contribution of two ROP GTPases, ROP2 and ROP6, to the cytoskeletal dynamics that regulate epidermal cell wall interdigitation has already been examined; however, how interactions between these molecules result in pattern formation remains to be elucidated. Here, we propose a simple interface equation model that incorporates both the cell wall remodeling activity of ROP GTPases and the diffusible signaling molecules by which they are regulated. This model successfully reproduces pattern formation observed in vivo, and explains the counterintuitive experimental results of decreased cellulose production and increased thickness. Our model also reproduces the dynamics of three-way cell wall junctions. Therefore, this model provides a possible mechanism for cell wall interdigitation formation in vivo. PMID:27054467

A differential optical interferometer for measuring short pulses of surface acoustic waves.

PubMed

Shaw, Anurupa; Teyssieux, Damien; Laude, Vincent

2017-09-01

The measurement of the displacements caused by the propagation of a short pulse of surface acoustic waves on a solid substrate is investigated. A stabilized time-domain differential interferometer is proposed, with the surface acoustic wave (SAW) sample placed outside the interferometer. Experiments are conducted with surface acoustic waves excited by a chirped interdigital transducer on a piezoelectric lithium niobate substrate having an operational bandwidth covering the 200-400MHz frequency range and producing 10-ns pulses with 36nm maximum out-of-plane displacement. The interferometric response is compared with a direct electrical measurement obtained with a receiving wide bandwidth interdigital transducer and good correspondence is observed. The effects of varying the path difference of the interferometer and the measurement position on the surface are discussed. Pulse compression along the chirped interdigital transducer is observed experimentally. Copyright © 2017 Elsevier B.V. All rights reserved.

Recent Progress in Micro-Supercapacitors with In-Plane Interdigital Electrode Architecture.

PubMed

Liu, Nishuang; Gao, Yihua

2017-12-01

Due to the boom of miniaturized electronic devices in the last decade, there are great demands for ultrathin and flexible on-chip rechargeable energy storage microdevices. Supercapacitor, as one of the most hopeful appearing energy storage devices, can provide a wonderful alternative to batteries or electrolytic capacitors, owing to its fast charge and discharge rates, high power density, and long cycling stability. Especially for the recently developed micro-supercapacitors, the unique in-plane interdigital electrode architecture can fully meet the integration requirements of rapidly developed miniaturized electronic devices, and improve the power density of the unit via shortening the ionic diffusion distance between the interdigital electrodes. This concept introduces the recent advances on the design, fabrication, and application of planar micro-supercapacitors for on-chip energy storage from an overall perspective. Moreover, challenges and future development trends are discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Integration of high capacity materials into interdigitated mesostructured electrodes for high energy and high power density primary microbatteries

NASA Astrophysics Data System (ADS)

Pikul, James H.; Liu, Jinyun; Braun, Paul V.; King, William P.

2016-05-01

Microbatteries are increasingly important for powering electronic systems, however, the volumetric energy density of microbatteries lags behind that of conventional format batteries. This paper reports a primary microbattery with energy density 45.5 μWh cm-2 μm-1 and peak power 5300 μW cm-2 μm-1, enabled by the integration of large volume fractions of high capacity anode and cathode chemistry into porous micro-architectures. The interdigitated battery electrodes consist of a lithium metal anode and a mesoporous manganese oxide cathode. The key enabler of the high energy and power density is the integration of the high capacity manganese oxide conversion chemistry into a mesostructured high power interdigitated bicontinuous cathode architecture and an electrodeposited dense lithium metal anode. The resultant energy density is greater than previously reported three-dimensional microbatteries and is comparable to commercial conventional format lithium-based batteries.

Epidemic models for phase transitions: application to a physical gel

NASA Astrophysics Data System (ADS)

Bilge, A. H.; Pekcan, O.; Kara, S.; Ogrenci, A. S.

2017-09-01

Carrageenan gels are characterized by reversible sol-gel and gel-sol transitions under cooling and heating processes and these transitions are approximated by generalized logistic growth curves. We express the transitions of carrageenan-water system, as a representative of reversible physical gels, in terms of a modified Susceptible-Infected-Susceptible epidemic model, as opposed to the Susceptible-Infected-Removed model used to represent the (irreversible) chemical gel formation in the previous work. We locate the gel point Tc of sol-gel and gel-sol transitions and we find that, for the sol-gel transition (cooling), Tc > Tsg (transition temperature), i.e. Tc is earlier in time for all carrageenan contents and moves forward in time and gets closer to Tsg as the carrageenan content increases. For the gel-sol transition (heating), Tc is relatively closer to Tgs; it is greater than Tgs, i.e. later in time for low carrageenan contents and moves backward as carrageenan content increases.

Ion Implantation with in-situ Patterning for IBC Solar Cells

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

Graff, John W.

2014-10-24

Interdigitated back-side Contact (IBC) solar cells are the highest efficiency silicon solar cells currently on the market. Unfortunately the cost to produce these solar cells is also very high, due to the large number of processing steps required. Varian believes that only the combination of high efficiency and low cost can meet the stated goal of $1/Wp. The core of this program has been to develop an in-situ patterning capability for an ion implantation system capable of producing patterned doped regions for IBC solar cells. Such a patterning capable ion implanter can reduce the number of process steps required tomore » manufacture IBC cells, and therefore significantly reduce the cost. The present program was organized into three phases. Phase I was to select a patterning approach and determine the patterning requirements for IBC cells. Phase II consists of construction of a Beta ion implantation system containing in-situ patterning capability. Phase III consists of shipping and installation of the ion implant system in a customer factory where it will be tested and proven in a pilot production line.« less

Novel and high-performance asymmetric micro-supercapacitors based on graphene quantum dots and polyaniline nanofibers

NASA Astrophysics Data System (ADS)

Liu, Wenwen; Yan, Xingbin; Chen, Jiangtao; Feng, Yaqiang; Xue, Qunji

2013-06-01

In comparison with graphene sheets, graphene quantum dots (GQDs) exhibit novel chemical/physical properties including nanometer-size, abundant edge defects, good electrical conductivity, high mobility, chemical inertia, stable photoluminescence and better surface grafting, making them promising for fabricating various novel devices. In the present work, an asymmetric micro-supercapacitor, using GQDs as negative active material and polyaniline (PANI) nanofibers as positive active material, is built for the first time by a simple and controllable two-step electro-deposition on interdigital finger gold electrodes. Electrochemical measurements reveal that the as-made GQDs//PANI asymmetric micro-supercapacitor has a more excellent rate capability (up to 1000 V s-1) than previously reported electrode materials, as well as faster power response capability (with a very short relaxation time constant of 115.9 μs) and better cycling stability after 1500 cycles in aqueous electrolyte. On this basis, an all-solid-state GQDs//PANI asymmetric micro-supercapacitor is fabricated using H3PO4-polyvinyl alcohol gel as electrolyte, which also exhibits desirable electrochemical capacitive performances. These encouraging results presented here may open up new insight into GQDs with highly promising applications in high-performance energy-storage devices, and further expand the potential applications of GQDs beyond the energy-oriented application of GQDs discussed above.In comparison with graphene sheets, graphene quantum dots (GQDs) exhibit novel chemical/physical properties including nanometer-size, abundant edge defects, good electrical conductivity, high mobility, chemical inertia, stable photoluminescence and better surface grafting, making them promising for fabricating various novel devices. In the present work, an asymmetric micro-supercapacitor, using GQDs as negative active material and polyaniline (PANI) nanofibers as positive active material, is built for the first time by a simple and controllable two-step electro-deposition on interdigital finger gold electrodes. Electrochemical measurements reveal that the as-made GQDs//PANI asymmetric micro-supercapacitor has a more excellent rate capability (up to 1000 V s-1) than previously reported electrode materials, as well as faster power response capability (with a very short relaxation time constant of 115.9 μs) and better cycling stability after 1500 cycles in aqueous electrolyte. On this basis, an all-solid-state GQDs//PANI asymmetric micro-supercapacitor is fabricated using H3PO4-polyvinyl alcohol gel as electrolyte, which also exhibits desirable electrochemical capacitive performances. These encouraging results presented here may open up new insight into GQDs with highly promising applications in high-performance energy-storage devices, and further expand the potential applications of GQDs beyond the energy-oriented application of GQDs discussed above. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01139a

A new sol-gel process for producing Na(2)O-containing bioactive glass ceramics.

PubMed

Chen, Qi-Zhi; Li, Yuan; Jin, Li-Yu; Quinn, Julian M W; Komesaroff, Paul A

2010-10-01

The sol-gel process of producing SiO(2)-CaO bioactive glasses is well established, but problems remain with the poor mechanical properties of the amorphous form and the bioinertness of its crystalline counterpart. These properties may be improved by incorporating Na(2)O into bioactive glasses, which can result in the formation of a hard yet biodegradable crystalline phase from bioactive glasses when sintered. However, production of Na(2)O-containing bioactive glasses by sol-gel methods has proved to be difficult. This work reports a new sol-gel process for the production of Na(2)O-containing bioactive glass ceramics, potentially enabling their use as medical implantation materials. Fine powders of 45S5 (a Na(2)O-containing composition) glass ceramic have for the first time been successfully synthesized using the sol-gel technique in aqueous solution under ambient conditions, with the mean particle size being approximately 5 microm. A comparative study of sol-gel derived S70C30 (a Na(2)O-free composition) and 45S5 glass ceramic materials revealed that the latter possesses a number of features desirable in biomaterials used for bone tissue engineering, including (i) the crystalline phase Na(2)Ca(2)Si(3)O(9) that couples good mechanical strength with satisfactory biodegradability, (ii) formation of hydroxyapatite, which may promote good bone bonding and (iii) cytocompatibility. In contrast, the sol-gel derived S70C30 glass ceramic consisted of a virtually inert crystalline phase CaSiO(3). Moreover, amorphous S70C30 largely transited to CaCO(3) with minor hydroxyapatite when immersed in simulated body fluid under standard tissue culture conditions. In conclusion, sol-gel derived Na(2)O-containing glass ceramics have significant advantages over related Na(2)O-free materials, having a greatly improved combination of mechanical capability and biological absorbability. 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

New materials with microgels

NASA Astrophysics Data System (ADS)

Kim, Jin-Woong

2009-03-01

This talk introduces a flexible and straightforward method for generating responsive microgel materials with new structures by using a microfluidic technique. We demonstrate that this approach enables tight control over the size and monodispersity of droplets as well as the interfacial structures, which is essential for determining release and transport kinetics of encapsulated components. We also show that responsiveness of microgel materials is controllable by tuning their structure, thereby allowing us to overcome the limitation of length scales, since the diffusion of water molecules through the structured gel phase is much faster than through a bulk gel phase of similar dimensions. We have generated a variety of novel gel structures: microgels with complex structures, microgel shells, 3D gel network with a truly fast response, and responsive colloidosomes. The robustness and versatility of this approach are expected to generate more complex systems and create new possibilities to develop novel materials in practical applications, including drug delivery, foods, and cosmetics.

Micelle Morphology and Mechanical Response of Triblock Gels

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

Seitz, Michelle E.; Burghardt, Wesley R.; Shull, Kenneth R.

2010-01-12

The effect of polymer concentration on mechanical response and micelle morphology of ABA and AB copolymers in B-selective solvents has been systematically studied. Micelle morphology was determined using a combination of small-angle X-ray scattering, shear, and birefringence while mechanical response at low and high strains was determined using indentation techniques. Self-consistent field theory calculations were used to determine micelle volume fraction profiles and to construct an equilibrium phase map. The transition from spherical to cylindrical micelles increases the triblock gel modulus and energy dissipation. Combining knowledge of gel relaxation time, which determines the rate at which the gel can equilibratemore » its micelle structure, with the equilibrium phase map allows estimation of the experimental temperatures and time scales over which kinetic trapping will arrest micelle structure evolution. Kinetic trapping enables cylindrical morphologies to be obtained at significantly lower polymer fractions than is possible in equilibrated systems.« less

Preparation and mechanical characterization of a PNIPA hydrogel composite.

PubMed

Liu, Kaifeng; Ovaert, Timothy C; Mason, James J

2008-04-01

A poly (N-isopropylacrylamide) (PNIPA) hydrogel was synthesized by free radical polymerization and reinforced with a polyurethane foam to make a hydrogel composite. The temperature dependence of the elastic modulus of the PNIPA hydrogel and the composite due to volume phase transition was found using a uniaxial compression test, and the swelling property was investigated using an equilibrium swelling ratio experiment. The gel composite preserves the ability to undergo the volume phase transition and its elastic modulus has strong temperature dependence. The temperature dependence of the elastic modulus and swelling ratio of the gel composite were compared to the PNIPA hydrogel. Not surprisingly, the modulus and swelling ratio of the composite were less dramatic than in the gel.

HPTN 035 Phase II/IIb Randomized Safety and Effectiveness Study of the Vaginal Microbicides BufferGel and 0.5% PRO 2000 for the Prevention of Sexually Transmitted Infections in Women

PubMed Central

Guffey, M. Bradford; Richardson, Barbra; Husnik, Marla; Makanani, Bonus; Chilongozi, David; Yu, Elmer; Ramjee, Gita; Mgodi, Nyaradzo; Gomez, Kailazarid; Hillier, Sharon L.; Karim, Salim Abdool

2014-01-01

Objectives To estimate the effectiveness of candidate microbicides BufferGel and 0.5% PRO 2000 Gel (P) (PRO 2000) for prevention of non-ulcerative sexually transmitted infections (STIs). Methods Between 2005 and 2007, 3099 women were enrolled in HIV Prevention Trials Network (HPTN) protocol 035, a phase II/IIb evaluation of the safety and effectiveness of BufferGel and PRO 2000 for prevention of sexually transmitted infections, including Neisseria gonorrhoeae (GC), Chlamydia trachomatis (CT), and Trichomonas vaginalis (TV). Incidences of STIs were determined by study arm, and hazard ratios (HRs) of BufferGel and PRO 2000 versus placebo gel or no gel control groups were computed using discrete time Andersen-Gill proportional hazards model. Results The overall incidence rates were 1.6/100 person-years at risk (PYAR) for GC, 3.9/100 PYAR for CT, and 15.3/100 PYAR for TV. For BufferGel versus placebo gel, HRs were 0.99 (95% CI 0.49–2.00), 1.00 (95% CI 0.64–1.57), and 0.95 (95% CI 0.71–1.25) for prevention of GC, CT, and TV respectively. For PRO 2000, HRs were 1.66 (95% CI 0.90–3.06), 1.16 (95% CI 0.76–1.79), and 1.18 (95% CI 0.90–1.53) for prevention of GC, CT, and TV respectively. Conclusions The incidence of STIs was high during HPTN 035 despite provision of free condoms and comprehensive risk-reduction counselling, highlighting the need for effective STI prevention programmes in this population. Unfortunately, candidate microbicides BufferGel and PRO2000 had no protective effect against gonorrhoea, Chlamydia, or trichomoniasis. PMID:24898857

MTN-017: A Rectal Phase 2 Extended Safety and Acceptability Study of Tenofovir Reduced-Glycerin 1% Gel

PubMed Central

Lama, Javier R.; Richardson, Barbra A.; Carballo-Diéguez, Alex; Kunjara Na Ayudhya, Ratiya Pamela; Liu, Karen; Patterson, Karen B.; Leu, Cheng-Shiun; Galaska, Beth; Jacobson, Cindy E.; Parikh, Urvi M.; Marzinke, Mark A.; Hendrix, Craig W.; Johnson, Sherri; Piper, Jeanna M.; Grossman, Cynthia; Ho, Ken S.; Lucas, Jonathan; Pickett, Jim; Bekker, Linda-Gail; Chariyalertsak, Suwat; Chitwarakorn, Anupong; Gonzales, Pedro; Holtz, Timothy H.; Liu, Albert Y.; Mayer, Kenneth H.; Zorrilla, Carmen; Schwartz, Jill L.; Rooney, James; McGowan, Ian

2017-01-01

Abstract Background. Human immunodeficiency virus (HIV) disproportionately affects men who have sex with men (MSM) and transgender women (TGW). Safe and acceptable topical HIV prevention methods that target the rectum are needed. Methods. MTN-017 was a phase 2, 3-period, randomized sequence, open-label, expanded safety and acceptability crossover study comparing rectally applied reduced-glycerin (RG) 1% tenofovir (TFV) and oral emtricitabine/TFV disoproxil fumarate (FTC/TDF). In each 8-week study period participants were randomized to RG-TFV rectal gel daily, or RG-TFV rectal gel before and after receptive anal intercourse (RAI; or at least twice weekly in the event of no RAI), or daily oral FTC/TDF. Results. MSM and TGW (n = 195) were enrolled from 8 sites in the United States, Thailand, Peru, and South Africa with mean age of 31.1 years (range 18-64). There were no differences in ≥grade 2 adverse event rates between daily gel (incidence rate ratio [IRR], 1.09; P = .59) or RAI gel (IRR, 0.90; P = .51) compared to FTC/TDF. High adherence (≥80% of prescribed doses assessed by unused product return and Short Message System reports) was less likely in the daily gel regimen (odds ratio [OR], 0.35; P < .001), and participants reported less likelihood of future daily gel use for HIV protection compared to FTC/TDF (OR, 0.38; P < .001). Conclusions. Rectal application of RG TFV gel was safe in MSM and TGW. Adherence and product use likelihood were similar for the intermittent gel and daily oral FTC/TDF regimens, but lower for the daily gel regimen. Clinical Trials Registration: NCT01687218. PMID:27986684

Supersonic aerodynamic characteristics of a low-aspect-ratio missile model with wing and tail controls and with tails in line and interdigitated

NASA Technical Reports Server (NTRS)

Graves, E. B.

1972-01-01

A study has been made to determine the aerodynamic characteristics of a low-aspect ratio cruciform missile model with all-movable wings and tails. The configuration was tested at Mach numbers from 1.50 to 4.63 with the wings in the vertical and horizontal planes and with the wings in a 45 deg roll plane with tails in line and interdigitated.

Estimation of activation energy for electroporation and pore growth rate in liquid crystalline and gel phases of lipid bilayers using molecular dynamics simulations.

PubMed

Majhi, Amit Kumar; Kanchi, Subbarao; Venkataraman, V; Ayappa, K G; Maiti, Prabal K

2015-11-28

Molecular dynamics simulations of electroporation in POPC and DPPC lipid bilayers have been carried out at different temperatures ranging from 230 K to 350 K for varying electric fields. The dynamics of pore formation, including threshold field, pore initiation time, pore growth rate, and pore closure rate after the field is switched off, was studied in both the gel and liquid crystalline (Lα) phases of the bilayers. Using an Arrhenius model of pore initiation kinetics, the activation energy for pore opening was estimated to be 25.6 kJ mol(-1) and 32.6 kJ mol(-1) in the Lα phase of POPC and DPPC lipids respectively at a field strength of 0.32 V nm(-1). The activation energy decreases to 24.2 kJ mol(-1) and 23.7 kJ mol(-1) respectively at a higher field strength of 1.1 V nm(-1). At temperatures below the melting point, the activation energy in the gel phase of POPC and DPPC increases to 28.8 kJ mol(-1) and 34.4 kJ mol(-1) respectively at the same field of 1.1 V nm(-1). The pore closing time was found to be higher in the gel than in the Lα phase. The pore growth rate increases linearly with temperature and quadratically with field, consistent with viscosity limited growth models.

Development of flexible SAW sensors for non-destructive testing of structure

NASA Astrophysics Data System (ADS)

Takpara, R.; Duquennoy, M.; Courtois, C.; Gonon, M.; Ouaftouh, M.; Martic, G.; Rguiti, M.; Jenot, F.; Seronveaux, L.; Pelegris, C.

2016-02-01

In order to accurately examine structures surfaces, it is interesting to use surface SAW (Surface Acoustic Wave). Such waves are well suited for example to detect early emerging cracks or to test the quality of a coating. In addition, when coatings are thin or when emergent cracks are precocious, it is necessary to excite surface waves beyond 10MHz. Finally, when structures are not flat, it makes sense to have flexible or conformable sensors for their characterization. To address this problem, we propose to develop SAW type of interdigital sensors (or IDT for InterDigital Transducer), based on flexible piezoelectric plates. Initially, in order to optimize these sensors, we modeled the behavior of these sensors and identified the optimum characteristic sizes. In particular, the thickness of the piezoelectric plate and the width of the interdigital electrodes have been studied. Secondly, we made composites based on barium titanate foams in order to have flexible piezoelectric plates and to carry out thereafter sensors. Then, we studied several techniques in order to optimize the interdigitated electrodes deposition on this type of material. One of the difficulties concerns the fineness of these electrodes because the ratio between the length (typically several millimeters) and the width (a few tens of micrometers) of electrodes is very high. Finally, mechanical, electrical and acoustical characterizations of the sensors deposited on aluminum substrates were able to show the quality of our achievement.

An Rf Focused Interdigital Ion Accelerating Structure

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

Swenson, D.A.

2003-08-26

An Rf Focused Interdigital (RFI) ion accelerating structure will be described. It represents an effective combination of the Wideroee (or interdigital) linac structure, used for many low frequency, heavy ion applications, and the rf electric quadrupole focusing used in the RFQ and RFD linac structures. As in the RFD linac structure, rf focusing is introduced into the RFI linac structure by configuring the drift tubes as two independent pieces operating at different electrical potentials as determined by the rf fields of the linac structure. Each piece (or electrode) of the RFI drift tube supports two fingers pointed inwards towards themore » opposite end of the drift tube forming a four-finger geometry that produces an rf quadrupole field along the axis of the linac for focusing the beam. However, because of the differences in the rf field configuration along the axis, the scheme for introducing rf focusing into the interdigital linac structure is quite different from that adopted for the RFD linac structure. The RFI linac structure promises to have significant size, efficiency, performance, and cost advantages over existing linac structures for the acceleration of low energy ion beams of all masses (light to heavy). These advantages will be reviewed. A 'cold model' of this new linac structure has been fabricated and the results of rf cavity measurements on this cold model will be presented.« less

Characterization of microstructure, viscoelasticity, heterogeneity and ergodicity in pectin-laponite-CTAB-calcium nanocomposite hydrogels.

PubMed

Joshi, Nidhi; Rawat, Kamla; Bohidar, H B

2016-01-20

In order to customize the viscoelastic properties of pectin gels, it is necessary to work on a composite platform. Herein, the gelation kinetics, and viscoelastic characterization of anionic polysaccharide pectin dispersion prepared in presence of nanoclay laponite are reported using dynamic light scattering and rheology measurements. The ratio Rg/Rh (Rg and Rh are radius of gyration and hydrodynamic radius respectively) determined from light scattering data revealed the presence of random coils of pectin chains inside the gel matrix. When nanoclay laponite was added to the pectin chains solution, two-phase separation was noticed instantaneously. Therefore, the surfactant cetyltrimethylammonium bromide [CTAB] was added to exfoliate the clay platelets in the dispersion, and also in its gel phase. The exfoliating agent cetyltrimethylammonium bromide ([CTAB]≈ cmc/10) helped to enhance the homogeneity and stability of the pectin-clay sols and gels. The storage and loss moduli (G' and G") of the composite gel changed significantly as function of nanoclay laponite content for concentration up to 0.03% (w/v) causing the softening of the gels (gel strength reduced by close to 50%) compared to pectin-calcium gel. However, as the concentration of nanoclay laponite was maintained between 0.01% and 0.03% (w/v), the gel rigidity (G') recovered by 30% (35-45 Pa). The transition from ergodic to non-ergodic state occurred during sol-gel transition owing to the presence of the nanoclay laponite. The gelation time was not too different from the ergodicity breaking time. Thus, the presence of nanoclay laponite in such minute concentration is shown to cause considerable change in the thermo-physical property of the composite gels. This material property modulation will facilitate designing of soft gels having storage modulus continuously varying in the wide range of 10-70 Pa while keeping the gelation temperature mostly unaltered. Copyright © 2015 Elsevier Ltd. All rights reserved.

Molecular Level Understanding of Sodium Dodecyl Sulfate (SDS) Induced Sol-Gel Transition of Pluronic F127 Using Fisetin as a Fluorescent Molecular Probe.

PubMed

Mishra, Jhili; Swain, Jitendriya; Mishra, Ashok Kumar

2018-01-11

The thermoreversible sol-gel transition of pluronic F127 is markedly altered even with addition of submicellar concentration of sodium dodecyl sulfate (SDS) surfactant. Multiple fluorescence parameters like fluorescence intensity, fluorescence anisotropy and fluorescence lifetime of both the prototropic forms (anion (A - *) and phototautomer FT*) of the photoprototropic fluorescent probe fisetin has been efficiently used to understand the molecular level properties like polarity and microviscosity of the PF127-SDS system as a function of temperature. The SDS-induced increase in the interfacial hydrophobicity level is seen to affect the sol-gel phase transition of PF127 (21-18 °C). The E T (30) polarity parameter value of anionic emission of fisetin suggests that there is a considerable decrease in the polarity of the PF127 medium with increase in temperature and with the addition of SDS. The microviscosity progressively increases from ∼5 mPa s (sol state, 10 °C) to ∼22.01 mPa s (gel state 35 °C) in aqueous solution of PF127. The variation in microviscosity with addition of SDS in PF127-SDS mixed system is significant in sol phase whereas in gel phase this variation is significantly less. Temperature dependent fluorescence lifetime of FT* indicates that there is heterogeneity in distribution of fisetin molecules at different domains of PF127. This work also show-cases the sensitivity of fisetin toward change in polarity and change in sol-gel transition temperature of copolymer PF127 with variation in temperature (both forward and reverse directions) and SDS.

Nonlinear dielectric properties of planar structures based on ferroelectric betaine phosphite films

NASA Astrophysics Data System (ADS)

Balashova, E. V.; Krichevtsov, B. B.; Svinarev, F. B.; Yurko, E. I.

2014-02-01

Ferroelectric films of partly deuterated betaine phosphite are grown on NdGaO3(001) substrates with an interdigitated system of electrodes on their surfaces by evaporation at room temperature. These films have a high capacitance in the ferroelectric phase transition range. The dielectric nonlinearity of the grown structures is studied in small-signal and strong-signal response modes and in the intermediate region between these two modes by measuring the capacitance in a dc bias field, dielectric hysteresis loops, and the Fourier spectra of an output signal in the Sawyer-Tower circuit. In the phase transition range, the capacitance control ratio at a bias voltage U bias = 40 V is K ≅ 7. The dielectric nonlinearity of the structures in the paraelectric phase is described by the Landau theory of second-order phase transitions. The additional contribution to the nonlinearity in the ferroelectric phase is related to the motion of domain walls and manifests itself when the input signal amplitude is higher than U st ˜ 0.7-1.0 V. The relaxation times of domain walls are determined from an analysis of the frequency dependences of the dielectric hysteresis.

Transdermal delivery of paeonol using cubic gel and microemulsion gel

PubMed Central

Luo, Maofu; Shen, Qi; Chen, Jinjin

2011-01-01

Background The aim of this study was to develop new systems for transdermal delivery of paeonol, in particular microemulsion gel and cubic gel formulations. Methods Various microemulsion vehicles were prepared using isopropyl myristate as an oil phase, polyoxyethylated castor oil (Cremophor® EL) as a surfactant, and polyethylene glycol 400 as a cosurfactant. In the optimum microemulsion gel formulation, carbomer 940 was selected as the gel matrix, and consisted of 1% paeonol, 4% isopropyl myristate, 28% Cremophor EL/polyethylene glycol 400 (1:1), and 67% water. The cubic gel was prepared containing 3% paeonol, 30% water, and 67% glyceryl monooleate. Results A skin permeability test using excised rat skins indicated that both the cubic gel and microemulsion gel formulations had higher permeability than did the paeonol solution. An in vivo pharmacokinetic study done in rats showed that the relative bioavailability of the cubic gel and microemulsion gel was enhanced by about 1.51-fold and 1.28-fold, respectively, compared with orally administered paeonol suspension. Conclusion Both the cubic gel and microemulsion gel formulations are promising delivery systems to enhance the skin permeability of paeonol, in particular the cubic gel. PMID:21904450

Robust aptamer sol-gel solid phase microextraction of very polar adenosine from human plasma.

PubMed

Mu, Li; Hu, Xiangang; Wen, Jianping; Zhou, Qixing

2013-03-01

Conventional solid phase microextraction (SPME) has a limited capacity to extract very polar analytes, such as adenosine. To solve this problem, aptamer conjugating sol-gel methodology was coupled with an SPME fiber. According to the authors' knowledge, this is the first reported use of aptamer SPME. The fiber of aptamer sol-gel SPME with a mesoporous structure has high porosity, large surface area, and small water contact angle. Rather than employing direct entrapment, covalent immobilization was the dominant method of aptamer loading in sol-gel. Aptamer sol-gel fiber captured a specified analyte from among the analog molecules, thereby, exhibiting an excellent selective property. Compared with commercial SPME fibers, this aptamer fiber was suitable for extracting adenosine, presenting an extraction efficiency higher than 20-fold. The values of repeatability and reproducibility expressed by relative standard deviation were low (9.4%). Interestingly, the sol-gel network enhanced the resistance of aptamer SPME to both nuclease and nonspecific proteins. Furthermore, the aptamer sol-gel fiber was applied in human plasma with LOQ 1.5 μg/L, which is an acceptable level. This fiber also demonstrates durability and regeneration over 20-cycles without significant loss of efficiency. Given the various targets (from metal ions to biomacromolecules and cells) of aptamers, this methodology will extend the multi-domain applications of SPME. Copyright © 2013 Elsevier B.V. All rights reserved.

Different Effects of Long- and Short-Chain Ceramides on the Gel-Fluid and Lamellar-Hexagonal Transitions of Phospholipids: A Calorimetric, NMR, and X-Ray Diffraction Study

PubMed Central

Sot, Jesús; Aranda, Francisco J.; Collado, M.-Isabel; Goñi, Félix M.; Alonso, Alicia

2005-01-01

The effects on dielaidoylphosphatidylethanolamine (DEPE) bilayers of ceramides containing different N-acyl chains have been studied by differential scanning calorimetry small angle x-ray diffraction and 31P-NMR spectroscopy. N-palmitoyl (Cer16), N-hexanoyl (Cer6), and N-acetyl (Cer2) sphingosines have been used. Both the gel-fluid and the lamellar-inverted hexagonal transitions of DEPE have been examined in the presence of the various ceramides in the 0-25 mol % concentration range. Pure hydrated ceramides exhibit cooperative endothermic order-disorder transitions at 93°C (Cer16), 60°C (Cer6), and 54°C (Cer2). In DEPE bilayers, Cer16 does not mix with the phospholipid in the gel phase, giving rise to high-melting ceramide-rich domains. Cer16 favors the lamellar-hexagonal transition of DEPE, decreasing the transition temperature. Cer2, on the other hand, is soluble in the gel phase of DEPE, decreasing the gel-fluid and increasing the lamellar-hexagonal transition temperatures, thus effectively stabilizing the lamellar fluid phase. In addition, Cer2 was peculiar in that no equilibrium could be reached for the Cer2-DEPE mixture above 60°C, the lamellar-hexagonal transition shifting with time to temperatures beyond the instrumental range. The properties of Cer6 are intermediate between those of the other two, this ceramide decreasing both the gel-fluid and lamellar-hexagonal transition temperatures. Temperature-composition diagrams have been constructed for the mixtures of DEPE with each of the three ceramides. The different behavior of the long- and short-chain ceramides can be rationalized in terms of their different molecular geometries, Cer16 favoring negative curvature in the monolayers, thus inverted phases, and the opposite being true of the micelle-forming Cer2. These differences may be at the origin of the different physiological effects that are sometimes observed for the long- and short-chain ceramides. PMID:15695626

Utility of colposcopy in a phase 2 portion of a microbicide clinical trial of BufferGel and 0.5% PRO 2000 Gel

PubMed Central

Chirenje, Zvavahera M; Mâsse, Benoît R; Maslankowski, Lisa A; Ramjee, Gita; Coletti, Anne S; Tembo, Tchangani N; Magure, Tsitsi M; Soto-Torres, Lydia; Kelly, Cliff; Hillier, Sharon; Karim, Abdool

2012-01-01

Background The majority of new HIV infections are acquired through heterosexual transmission. There is urgent need for prevention methods to compliment behavior change and condom use. Topical microbicide represent a potential strategy for reduction of HIV transmission in women. Methods Monthly Colposcopy evaluations were performed during pelvic examinations among 299 women enrolled in the Phase 2 portion of HPTN 035 study at four sites (1 in USA, 3 in Southern Africa). This was a phase 2/2b, multisite, randomized, and controlled clinical trial with four arms: BufferGel, 0.5% PRO2000 Gel, placebo gel and no gel. At two of the sites, pelvic examinations were conducted by the use of naked eye without colposcopy. Results A colposcopy finding of any kind was detected in 48% of participants at baseline compared to 40% at 3 months (p =0.04). The lower rates were also observed in vaginal discharge (22% at baseline, 16% at 3 months, p=0.06), erythema (15% at baseline, 8% at 3 months, p=0.004). The trend towards significance at p=0.05 disappear when utilizing stringent statistical significance levels. A pelvic finding of any kind was detected in 71% of colposcopy participants compared to 41% of participants who had naked eye examination only conducted at two sites that performed both colposcopy and naked eye without colposcopy. Use of colposcopy yielded significantly higher rates of participants with deep epithelial disruption, erythema and ecchymosis. We observed no cases of incident Chlamydia, Gonorrhea, or Syphilis during the three month follow up. There were 2 cases of incident HIV during 3-month study period neither of which was associated with any abnormal colposcopy evaluation findings. Conclusion No safety signals were observed in the 4 study arms, allowing seamless transition from phase 2 to 2b. Colposcopy utility in microbicide clinical trials has minimal value given high rates of background noise findings of no relevant clinical significance. PMID:22944480

Utility of colposcopy in a phase 2 portion of a microbicide clinical trial of BufferGel and 0.5% PRO 2000 Gel.

PubMed

Chirenje, Zvavahera M; Mâsse, Benoît R; Maslankowski, Lisa A; Ramjee, Gita; Coletti, Anne S; Tembo, Tchangani N; Magure, Tsitsi M; Soto-Torres, Lydia; Kelly, Cliff; Hillier, Sharon; Karim, Abdool

2012-08-27

The majority of new HIV infections are acquired through heterosexual transmission. There is urgent need for prevention methods to compliment behavior change and condom use. Topical microbicide represent a potential strategy for reduction of HIV transmission in women. Monthly Colposcopy evaluations were performed during pelvic examinations among 299 women enrolled in the Phase 2 portion of HPTN 035 study at four sites (1 in USA, 3 in Southern Africa). This was a phase 2/2b, multisite, randomized, and controlled clinical trial with four arms: BufferGel, 0.5% PRO2000 Gel, placebo gel and no gel. At two of the sites, pelvic examinations were conducted by the use of naked eye without colposcopy. A colposcopy finding of any kind was detected in 48% of participants at baseline compared to 40% at 3 months (p =0.04). The lower rates were also observed in vaginal discharge (22% at baseline, 16% at 3 months, p=0.06), erythema (15% at baseline, 8% at 3 months, p=0.004). The trend towards significance at p=0.05 disappear when utilizing stringent statistical significance levels. A pelvic finding of any kind was detected in 71% of colposcopy participants compared to 41% of participants who had naked eye examination only conducted at two sites that performed both colposcopy and naked eye without colposcopy. Use of colposcopy yielded significantly higher rates of participants with deep epithelial disruption, erythema and ecchymosis. We observed no cases of incident Chlamydia, Gonorrhea, or Syphilis during the three month follow up. There were 2 cases of incident HIV during 3-month study period neither of which was associated with any abnormal colposcopy evaluation findings. No safety signals were observed in the 4 study arms, allowing seamless transition from phase 2 to 2b. Colposcopy utility in microbicide clinical trials has minimal value given high rates of background noise findings of no relevant clinical significance.

Thermodynamics of Indomethacin Adsorption to Phospholipid Membranes.

PubMed

Fearon, Amanda D; Stokes, Grace Y

2017-11-22

Using second-harmonic generation, we directly monitored adsorption of indomethacin, a nonsteroidal anti-inflammatory drug, to supported lipid bilayers composed of phospholipids of varying phase, cholesterol content, and head group charge without the use of extrinsic labels at therapeutically relevant aqueous concentrations. Indomethacin adsorbed to gel-phase lipids with a high binding affinity, suggesting that like other arylacetic acid-containing drugs, it preferentially interacts with ordered lipid domains. We discovered that adsorption of indomethacin to gel-phase phospholipids was endothermic and entropically driven, whereas adsorption to fluid-phase phospholipids was exothermic and enthalpically driven. As temperature increased from 19 to 34 °C, binding affinities to gel-phase lipids increased by 7-fold but relative surface concentration decreased to one-fifth of the original value. We also compared our results to the entropies reported for indomethacin adsorbed to surfactant micelles, which are used in drug delivery systems, and assert that adsorbed water molecules in the phospholipid bilayer may be buried deeper into the acyl chains and less accessible for disruption. The thermodynamic studies reported here provide mechanistic insight into indomethacin interactions with mammalian plasma membranes in the gastrointestinal tract and inform studies of drug delivery, where indomethacin is commonly used as a prototypical, hydrophobic small-molecule drug.

Rectal Microbicide Development

PubMed Central

McGowan, Ian

2013-01-01

Purpose of review Individuals practicing unprotected receptive anal intercourse are at particularly high risk of HIV infection. Men who have sex with men (MSM) in the developed and developing world continue to have disproportionate and increasing levels of HIV infection. The last few years have seen important progress in demonstrating the efficacy of oral pre-exposure prophylaxis (PrEP), vaginal microbicides, and treatment as prevention but there has also been significant progress in the development of rectal microbicides (RM). The purpose of this review is to summarize the status of RM research and to identify opportunities, challenges, and future directions in this important field of HIV prevention. Recent findings Recent Phase 1 RM studies have characterized the safety, acceptability, compartmental pharmacokinetics (PK), and pharmacodynamics (PD) of both UC781 and tenofovir gels. The tenofovir gel formulation used in vaginal studies was not well tolerated in the rectum and newer rectal specific formulations have been developed and evaluated in Phase 1 studies. Summary Complex Phase 1 studies have provided important data on candidate RMs. Tenofovir gel is poised to move into Phase 2 evaluation and it is possible that a Phase 2B/3 effectiveness study could be initiated in the next 2–3 years. PMID:23032732

Rectal microbicide development.

PubMed

McGowan, Ian

2012-11-01

Individuals practicing unprotected receptive anal intercourse are at particularly high risk of HIV infection. Men who have sex with men (MSM) in the developed and developing world continue to have disproportionate and increasing levels of HIV infection. The past few years have seen important progress in demonstrating the efficacy of oral pre-exposure prophylaxis (PrEP), vaginal microbicides, and treatment as prevention, but there has also been significant progress in the development of rectal microbicides. The purpose of this review is to summarize the status of rectal microbicide research and to identify opportunities, challenges, and future directions in this important field of HIV prevention. Recent phase 1 rectal microbicide studies have characterized the safety, acceptability, compartmental pharmacokinetics, and pharmacodynamics of both UC781 and tenofovir gels. The tenofovir gel formulation used in vaginal studies was not well tolerated in the rectum and newer rectal-specific formulations have been developed and evaluated in phase 1 studies. Complex phase 1 studies have provided important data on candidate rectal microbicides. Tenofovir gel is poised to move into phase 2 evaluation and it is possible that a phase 2B/3 effectiveness study could be initiated in the next 2-3 years.

Luteal phase bleeding after IVF cycles: comparison between progesterone vaginal gel and intramuscular progesterone and correlation with pregnancy outcomes

PubMed Central

Jabara, Sami; Barnhart, Kurt; Schertz, Joan C; Patrizio, Pasquale

2009-01-01

Background: To compare luteal phase bleeding and pregnancy outcomes in normogonadotropic patients receiving progesterone vaginal gel (PVG) or intramuscular progesterone (IMP) injections. Methods: In this retrospective cohort study, data from 270 patients (292 cycles) undergoing day-3 fresh embryo transfer were analyzed. PVG, 90 mg daily (170 cycles) or IMP, 50 mg daily (122 cycles) began at egg retrieval. Results: Luteal phase bleeding was significantly more common in the PVG than the IMP group. No significant differences were observed in biochemical pregnancy or spontaneous abortion rates between the two groups. Patients who bled before the pregnancy test had significantly lower total and clinical pregnancy rates than non-bleeders. Total and ongoing pregnancy/delivery rates were higher in the PVG than IMP group, but did not achieve statistical significance. Conclusion: Luteal phase bleeding was more common in the PVG group than the IMP group, but pregnancy was successful in more patients in the PVG group. Luteal phase bleeding is prevented or delayed during IMP treatment, but patients who bled before the pregnancy test, whether using the gel or injected progesterone, had significantly reduced pregnancy rates compared with non-bleeders. PMID:20485581

A Theoretical Evaluation of Secondary Atomization Effects on Engine Performance for Aluminum Gel Propellants

NASA Technical Reports Server (NTRS)

Mueller, D. C.; Turns, S. R.

1994-01-01

A one-dimensional model of a gel-fueled rocket combustion chamber has been developed. This model includes the processes of liquid hydrocarbon burnout, secondary atomization. aluminum ignition, and aluminum combustion. Also included is a model of radiative heat transfer from the solid combustion products to the chamber walls. Calculations indicate that only modest secondary atomization is required to significantly reduce propellant burnout distances, aluminum oxide residual size and radiation heat wall losses. Radiation losses equal to approximately 2-13 percent of the energy released during combustion were estimated. A two-dimensional, two-phase nozzle code was employed to estimate radiation and nozzle two-phase flow effects on overall engine performance. Radiation losses yielded a 1 percent decrease in engine I(sub sp). Results also indicate that secondary atomization may have less effect on two-phase losses than it does on propellant burnout distance and no effect if oxide particle coagulation and shear induced droplet breakup govern oxide particle size. Engine I(sub sp) was found to decrease from 337.4 to 293.7 seconds as gel aluminum mass loading was varied from 0-70 wt percent. Engine I(sub sp) efficiencies, accounting for radiation and two-phase flow effects, on the order of 0.946 were calculated for a 60 wt percent gel, assuming a fragmentation ratio of 5.

Phase Behavior of Salt-Free Polyelectrolyte Gel-Surfactant Systems.

PubMed

Andersson, Martin; Hansson, Per

2017-06-22

Ionic surfactants tend to collapse the outer parts of polyelectrolyte gels, forming shells that can be used to encapsulate other species including protein and peptide drugs. In this paper, the aqueous phase behavior of covalently cross-linked polyacrylate networks containing sodium ions and dodecyltrimethylammonium ions as counterions is investigated by means of swelling isotherms, dye staining, small-angle X-ray scattering, and confocal Raman spectroscopy. The equilibrium state is approached by letting the networks absorb pure water. With an increasing fraction of surfactant ions, the state of the water-saturated gels is found to change from being swollen and monophasic, via multiphasic states, to collapsed and monophasic. The multiphasic gels have a swollen, micelle-lean core surrounded by a collapsed, micelle-rich shell, or a collapsed phase forming a spheroidal inner shell separating two micelle-lean parts. It is shown that the transition between monophasic and core-shell states can be induced by variation of the osmotic pressure and variation of the charge of the micelles by forming mixed micelles with the nonionic surfactant octaethyleneglycol monododecylether. The experimental data are compared with theoretical predictions of a model derived earlier. In the calculations, the collapsed shell is assumed to be homogeneous, an approximation introduced here and shown to be excellent for a wide range of compositions. The theoretical results highlight the electrostatic and hydrophobic driving forces behind phase separation.

Detection of human immunodeficiency virus type 1 (HIV-1) Tat protein by aptamer-based biosensors

NASA Astrophysics Data System (ADS)

Hashim, Uda; Fatin, M. F.; Ruslinda, A. R.; Gopinath, Subash C. B.; Uda, M. N. A.

2017-03-01

A study was conducted to detect the human immunodeficiency virus (HIV-1) Tat protein using interdigitated electrodes. The measurements and images of the IDEs' finger gaps and the images of chitosan-carbon nanotubes deposited on top of the interdigitated electrodes were taken using the Scanning Electron Microscope. The detection of HIV-1 Tat protein was done using split aptamers and aptamer tail. Biosensors were chosen as diagnostic equipment due to their rapid diagnostic capabilities.

Local Crystalline Structure in an Amorphous Protein Dense Phase

PubMed Central

Greene, Daniel G.; Modla, Shannon; Wagner, Norman J.; Sandler, Stanley I.; Lenhoff, Abraham M.

2015-01-01

Proteins exhibit a variety of dense phases ranging from gels, aggregates, and precipitates to crystalline phases and dense liquids. Although the structure of the crystalline phase is known in atomistic detail, little attention has been paid to noncrystalline protein dense phases, and in many cases the structures of these phases are assumed to be fully amorphous. In this work, we used small-angle neutron scattering, electron microscopy, and electron tomography to measure the structure of ovalbumin precipitate particles salted out with ammonium sulfate. We found that the ovalbumin phase-separates into core-shell particles with a core radius of ∼2 μm and shell thickness of ∼0.5 μm. Within this shell region, nanostructures comprised of crystallites of ovalbumin self-assemble into a well-defined bicontinuous network with branches ∼12 nm thick. These results demonstrate that the protein gel is comprised in part of nanocrystalline protein. PMID:26488663

Polymorphism and mesomorphism of oligomeric surfactants: effect of the degree of oligomerization.

PubMed

Jurašin, D; Pustak, A; Habuš, I; Šmit, I; Filipović-Vinceković, N

2011-12-06

A series of cationic oligomeric surfactants (quaternary dodecyldimethylammonium ions with two, three, or four chains connected by an ethylene spacer at the headgroup level, abbreviated as dimer, trimer, and tetramer) were synthesized and characterized. The influence of the degree of oligomerization on their polymorphic and mesomorphic properties was investigated by means of X-ray diffraction, polarizing optical microscopy, thermogravimetry, and differential scanning calorimetry. All compounds display layered arrangements with interdigitated dodecyl chains. The increase in the degree of oligomerization increases the interlayer distance and decreases the ordering in the solid phase; whereas the dimer sample is fully crystalline with well-developed 3D ordering and the trimer and tetramer crystallize as highly ordered crystal smectic phases. The number of thermal phase transitions and sequence of phases are markedly affected by the number of dodecyl chains. Anhydrous samples exhibit polymorphism and thermotropic mesomorphism of the smectic type, with the exception of the tetramer that displays only transitions at higher temperature associated with decomposition and melting. All hydrated compounds form lyotropic mesophases showing reversible phase transitions upon heating and cooling. The sequence of liquid-crystalline phases for the dimer, typical of concentrated ionic surfactant systems, comprises a hexagonal phase at lower temperatures and a smectic phase at higher temperatures. In contrast, the trimer and tetramer reveal textures of the hexagonal phase. © 2011 American Chemical Society

Changes in viscosity behavior from a normal organogelator to a heat-induced gelator for a long-chain amidoamine derivative.

PubMed

Morita, Clara; Sugimoto, Hiroki; Matsue, Keisuke; Kondo, Takeshi; Imura, Yoshiro; Kawai, Takeshi

2010-11-14

A long-chain amidoamine derivative (C18AA) acts as a normal organogelator in toluene, but changes to a heat-induced gelator, exhibiting a phase transition from sol to gel on heating upon addition of aqueous LiCl to the toluene gel. The thermal response of the heat-induced gel of C18AA was highly sensitive.

Separation of Aeruginosin-865 from Cultivated Soil Cyanobacterium (Nostoc sp.) by Centrifugal Partition Chromatography combined with Gel Permeation Chromatography.

PubMed

Cheel, José; Minceva, Mirjana; Urajová, Petra; Aslam, Rabya; Hrouzek, Pavel; Kopecký, Jiří

2015-10-01

Aeruginosin-865 was isolated from cultivated soil cyanobacteria using a combination of centrifugal partition chromatography (CPC) and gel permeation chromatography. The solubility of Aer-865 in different solvents was evaluated using the conductor-like screening model for real solvents (COSMO-RS). The CPC separation was performed in descending mode with a biphasic solvent system composed of water-n-BuOH-acetic acid (5:4:1, v/v/v). The upper phase was used as a stationary phase, whereas the lower phase was employed as a mobile phase at a flow rate of 10 mL/min. The revolution speed and temperature of the separation column were 1700 rpm and 25 degrees C, respectively. Preparative CPC separation followed by gel permeation chromatography was performed on 50 mg of crude extract yielding Aer-865 (3.5 mg), with a purity over 95% as determined by HPLC. The chemical identity of the isolated compound was confirmed by comparing its spectroscopic data (UV, HRESI-MS, HRESI-MS/MS) with those of an authentic standard and data available in the literature.

Lamellar Biogels: Fluid-Membrane-Based Hydrogels Containing Polymer Lipids

NASA Astrophysics Data System (ADS)

Warriner, Heidi E.; Idziak, Stefan H. J.; Slack, Nelle L.; Davidson, Patrick; Safinya, Cyrus R.

1996-02-01

A class of lamellar biological hydrogels comprised of fluid membranes of lipids and surfactants with small amounts of low molecular weight poly(ethylene glycol)-derived polymer lipids (PEG-lipids) were studied by x-ray diffraction, polarized light microscopy, and rheometry. In contrast to isotropic hydrogels of polymer networks, these membrane-based birefringent liquid crystalline biogels, labeled Lα,g, form the gel phase when water is added to the liquid-like lamellar L_α phase, which reenters a liquid-like mixed phase upon further dilution. Furthermore, gels with larger water content require less PEG-lipid to remain stable. Although concentrated (~50 weight percent) mixtures of free PEG (molecular weight, 5000) and water do not gel, gelation does occur in mixtures containing as little as 0.5 weight percent PEG-lipid. A defining signature of the Lα,g regime as it sets in from the fluid lamellar L_α phase is the proliferation of layer-dislocation-type defects, which are stabilized by the segregation of PEG-lipids to the defect regions of high membrane curvature that connect the membranes.

Molecularly imprinted polymer online solid-phase extraction coupled with high-performance liquid chromatography-UV for the determination of three sulfonamides in pork and chicken.

PubMed

He, Jinxing; Wang, Shuo; Fang, Guozhen; Zhu, Huaping; Zhang, Yan

2008-05-14

A selective imprinted amino-functionalized silica gel sorbent was prepared by combining a surface molecular imprinting technique with a sol-gel process for online solid-phase extraction-HPLC determination of three trace sulfonamides in pork and chicken muscle. The imprinted functionalized silica gel sorbent exhibited selectivity and fast kinetics for the adsorption and desorption of sulfonamides. With a sample loading flow rate of 4 mL min (-1) for 12.5 min, enhancement factors and detection limits for three sulfonamides ( S/ N = 3) were achieved. The precision (RSD) for nine replicate online sorbent extractions of 5 microg L (-1) sulfonamides was less than 4.5%. The sorbent also offered good linearity ( r (2) > 0.99) for online solid-phase extraction of trace levels of sulfonamides. The method was applied to the determination of sulfonamides in pork and chicken muscle samples. The prepared polymer sorbent shows promise for online solid-phase extraction for HPLC determination of trace levels of sulfonamides in pork and chicken samples.

Structural investigations of sol-gel derived silicate gels using Eu 3+ ion-probe luminescence

NASA Astrophysics Data System (ADS)

Secu, C. E.; Predoi, D.; Secu, M.; Cernea, M.; Aldica, G.

2009-09-01

Undoped and Eu 3+-doped CaF 2-SiO 2 gels were prepared by the sol-gel method and their optical properties have been studied. The UV-VIS-NIR absorption and photoluminescence spectra have shown the bands typical for the Eu 3+ ions transitions. When the Eu-doped gel is annealed at temperatures up to 800 °C (i.e. above the CaF 2 crystallisation peak at ˜460 °C) the photoluminescence spectra intensity increase, the 590 nm (5D→7F) and 620 nm (5D→7F) luminescence bands become comparable and a structuring of the 620 nm band is observed. The phonon sidebands peaks associated with the 5F→7D transition of the Eu 3+ ion were observed at around 1000 and 620 cm -1 and have been assigned to the Si-O and Ca-O bonds, respectively. A phonon sideband signal in the range of 300-400 cm -1 was attributed to Ca-F bonds in the precipitated CaF 2 phase. From the optical absorption, photoluminescence and phonon sidebands spectra we have concluded that in the gels annealed at 800 °C, the Eu 3+ ions are incorporated into the silica network and in the precipitated CaF 2 phase.

Dose-ranging phase 1 study of TMC120, a promising vaginal microbicide, in HIV-negative and HIV-positive female volunteers.

PubMed

Jespers, Vicky A; Van Roey, Jens M; Beets, Greet I; Buvé, Anne M

2007-02-01

To evaluate the short-term safety, tolerability, and systemic exposure of a vaginal microbicide gel containing the nonnucleoside reverse transcriptase inhibitor TMC120. Randomized, controlled, double-blind, phase 1 trial of a gel containing 3 different concentrations of TMC120 versus placebo. Of the 48 HIV-negative and 16 HIV-positive women enrolled, 52 women received active product. Participants applied the gel twice daily for 7 days and were assessed on 6 occasions. Colposcopic evaluation was performed before and after first gel application and on day 8. Laboratory safety assessments were carried out on all visits except day 7. Plasma levels of TMC120 were measured on days 1 and 7. All TMC120 concentrations were well tolerated, and there were no apparent differences in safety parameters. Four women (6%) had treatment-emergent mild cervical findings (petechiae in 3 women and erythema in 1 woman) of <5 mm. Plasma levels of TMC120 were quantifiable on day 1 in 7 (13%) participants and on day 7 in 39 (75%) participants using TMC120 gel. The TMC120 vaginal gel was well-tolerated in this short study by HIV-negative and HIV-positive women. The implications of the absorption of TMC120 should be studied further in expanded safety and effectiveness trials.

Concentration-dependent effect of melatonin on DSPC membrane

NASA Astrophysics Data System (ADS)

Sahin, Ipek; Bilge, Duygu; Kazanci, Nadide; Severcan, Feride

2013-11-01

The concentration-induced effects of melatonin on distearoyl phosphatidylcholine (DSPC) model membranes were investigated by using two different non-invasive techniques, namely Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). An investigation of the Csbnd H, Cdbnd O and PO2- double bond stretching mode in FTIR spectra and DSC studies reveals that the inclusion of melatonin changes the physical properties of the DSPC multilamellar liposomes (MLVs) by shifting the main phase transition to lower temperatures, abolishing the pretransition, ordering the system in the gel phase and slightly disordering the system in the liquid crystalline phase, increasing the dynamics both in the gel phase and liquid crystalline phases. Melatonin also causes strong hydrogen bonding between Cdbnd O and PO2- groups of lipids and the water molecules around.

Development and validation of reversed phase high performance liquid chromatography method for determination of dexpanthenol in pharmaceutical formulations.

PubMed

Kulikov, A U; Zinchenko, A A

2007-02-19

This paper describes the validation of an isocratic HPLC method for the assay of dexpanthenol in aerosol and gel. The method employs the Vydac Proteins C4 column with a mobile phase of aqueous solution of trifluoroacetic acid and UV detection at 206 nm. A linear response (r>0.9999) was observed in the range of 13.0-130 microg mL(-1). The method shows good recoveries and intra and inter-day relative standard deviations were less than 1.0%. Validation parameters as specificity, accuracy and robustness were also determined. The method can be used for dexpanthenol assay of panthenol aerosol and gel with dexpanthenol as the method separates dexpanthenol from aerosol or gel excipients.

Condition of Development of Channeled Flow in Analogue Partially Molten Medium

NASA Astrophysics Data System (ADS)

Takashima, S.; Kumagai, I.; Kurita, K.

2003-12-01

Melt migration in partially molten medium is conceptually classified into two contrasting models; homogeneous permeable flow and localized channeled flow. The transition from homogeneous flow to localized one is promoted with advance of melting and deformation of the medium, but the physics behind this transition is not yet clarified well. Here we show two kinds of experimental results which are mutually related. One is a development of the channeled flow in a so-called Rayleigh-Taylor Instability experiments. Dense viscous fluid is poured at the top of the matrix fluid; homogeneous mixture of soft transparent gel and viscous fluid having equal density. Liquid fraction is varied for this matrix fluid to see how the fraction controls the development. At the intermediate gel fraction (between70% to about 40%) the dense fluid at first migrates through the grain boundary as permeable flow. But local heterogeneity in the gel fraction induces relative movement of solid phase, which in turns enhances the localization of the flow and deformation. We measured the motion of fluid phase and solid phase separately by PIV/PTV methods. Estimated relative motion and divergence of velocity field of the solid phase show that the state in the relative movement of the solid phase could cause heterogeneous distribution of the solid fraction. The deformation-induced compaction plays an important role. The second experimental result is rheology of the dense suspension of soft gel and viscous fluid. Deformation experiment with concentric cylinders shows that the mixture system has yield strength at the intermediate gel fraction. In the stress state above the yield strength the region where deformation rate is large has low viscosity and its internal structure evolves to the state in heterogeneous distribution of viscosity. We would like to show that this nature is critical in the development of flow from homogeneous one to localized one.

Localization and Ordering of Lipids Around Aquaporin-0: Protein and Lipid Mobility Effects.

PubMed

Briones, Rodolfo; Aponte-Santamaría, Camilo; de Groot, Bert L

2017-01-01

Hydrophobic matching, lipid sorting, and protein oligomerization are key principles by which lipids and proteins organize in biological membranes. The Aquaporin-0 channel (AQP0), solved by electron crystallography (EC) at cryogenic temperatures, is one of the few protein-lipid complexes of which the structure is available in atomic detail. EC and room-temperature molecular dynamics (MD) of dimyristoylglycerophosphocholine (DMPC) annular lipids around AQP0 show similarities, however, crystal-packing and temperature might affect the protein surface or the lipids distribution. To understand the role of temperature, lipid phase, and protein mobility in the localization and ordering of AQP0-lipids, we used MD simulations of an AQP0-DMPC bilayer system. Simulations were performed at physiological and at DMPC gel-phase temperatures. To decouple the protein and lipid mobility effects, we induced gel-phase in the lipids or restrained the protein. We monitored the lipid ordering effects around the protein. Reducing the system temperature or inducing lipid gel-phase had a marginal effect on the annular lipid localization. However, restraining the protein mobility increased the annular lipid localization around the whole AQP0 surface, resembling EC. The distribution of the inter-phosphate and hydrophobic thicknesses showed that stretching of the DMPC annular layer around AQP0 surface is the mechanism that compensates the hydrophobic mismatch in this system. The distribution of the local area-per-lipid and the acyl-chain order parameters showed particular fluid- and gel-like areas that involved several lipid layers. These areas were in contact with the surfaces of higher and lower protein mobility, respectively. We conclude that the AQP0 surfaces induce specific fluid- and gel-phase prone areas. The presence of these areas might guide the AQP0 lipid sorting interactions with other membrane components, and is compatible with the squared array oligomerization of AQP0 tetramers separated by a layer of annular lipids.

Ultrasensitive interdigitated capacitance immunosensor using gold nanoparticles.

PubMed

Alizadeh Zeinabad, Hojjat; Ghourchian, Hedayatollah; Falahati, Mojtaba; Fathipour, Morteza; Azizi, Marzieh; Boutorabi, Seyed Mehdi

2018-06-29

Immunosensors based on interdigitated electrodes (IDEs), have recently demonstrated significant improvements in the sensitivity of capacitance detection. Herein, a novel type of highly sensitive, compact and portable immunosensor based on a gold interdigital capacitor has been designed and developed for the rapid detection of hepatitis B surface antigen (HBsAg). To improve the efficiency of antibody immobilization and time-saving, a self-assembled monolayer (SAM) of 2-mercaptoethylamine film was coated on IDEs. Afterwards, carboxyl groups on primary antibodies were activated through 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and were immobilized on amino-terminated SAM for better control of the oriented immobilization of antibodies on gold IDEs. In addition, gold nanoparticles conjugated with a secondary antibody were used to enhance the sensitivity. Under optimal conditions, the immunosensor exhibited the sensitivity of 0.22 nF.pg ml -1 , the linear range from 5 pg ml -1 to 1 ng ml -1 and the detection limit of 1.34 pg ml -1 , at a signal-to-noise ratio of 3.

Topical treatment of tinea pedis using 6% coriander oil in unguentum leniens: a randomized, controlled, comparative pilot study.

PubMed

Beikert, F C; Anastasiadou, Z; Fritzen, B; Frank, U; Augustin, M

2013-01-01

The antifungal activity of coriander oil has already been demonstrated in vitro. Evaluation of the efficacy and tolerability of 6% coriander oil in unguentum leniens in the treatment of interdigital tinea pedis. Half-side comparative pilot study on subjects with symmetric, bilateral interdigital tinea pedis. Active drug and placebo control were applied twice daily on the affected areas, and follow-up visits were performed on days 14 and 28. 40 participants (mean age 52.5 years, 60% male) were included in the study. For 6% coriander oil in unguentum leniens, a highly significant improvement of the clinical signs (p < 0.0001) was observed during the entire observation period; the number of positive fungal cultures also tended to decrease (p = 0.0654). The tolerability of the tested substances was good. Coriander oil is effective and well tolerated in the treatment of interdigital tinea pedis. Copyright © 2013 S. Karger AG, Basel.

Ultrasensitive interdigitated capacitance immunosensor using gold nanoparticles

NASA Astrophysics Data System (ADS)

Alizadeh Zeinabad, Hojjat; Ghourchian, Hedayatollah; Falahati, Mojtaba; Fathipour, Morteza; Azizi, Marzieh; Boutorabi, Seyed Mehdi

2018-06-01

Immunosensors based on interdigitated electrodes (IDEs), have recently demonstrated significant improvements in the sensitivity of capacitance detection. Herein, a novel type of highly sensitive, compact and portable immunosensor based on a gold interdigital capacitor has been designed and developed for the rapid detection of hepatitis B surface antigen (HBsAg). To improve the efficiency of antibody immobilization and time-saving, a self-assembled monolayer (SAM) of 2-mercaptoethylamine film was coated on IDEs. Afterwards, carboxyl groups on primary antibodies were activated through 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and were immobilized on amino-terminated SAM for better control of the oriented immobilization of antibodies on gold IDEs. In addition, gold nanoparticles conjugated with a secondary antibody were used to enhance the sensitivity. Under optimal conditions, the immunosensor exhibited the sensitivity of 0.22 nF.pg ml–1, the linear range from 5 pg ml‑1 to 1 ng ml–1 and the detection limit of 1.34 pg ml‑1, at a signal-to-noise ratio of 3.

A new design of a miniature filter on microstrip resonators with an interdigital structure of conductors

NASA Astrophysics Data System (ADS)

Belyaev, B. A.; Serzhantov, A. M.; Bal'va, Ya. F.; Leksikov, An. A.; Galeev, R. G.

2015-05-01

A microstrip bandpass filter of new design based on original resonators with an interdigital structure of conductors has been studied. The proposed filters of third to sixth order are distinguished for their high frequency-selective properties and much smaller size than analogs. It is established that a broad stop band, extending up to a sixfold central bandpass frequency, is determined by low unloaded Q of higher resonance mode and weak coupling of resonators in the pass band. It is shown for the first time that, as the spacing of interdigital stripe conductors decreases, the Q of higher resonance mode monotonically drops, while the Q value for the first operating mode remains high. A prototype fourth-order filter with a central frequency of 0.9 GHz manufactured on a ceramic substrate with dielectric permittivity ɛ = 80 has microstrip topology dimensions of 9.5 × 4.6 × 1 mm3. The electrodynamic 3D model simulations of the filter characteristics agree well with the results of measurements.

Ozone Sensing Based on Palladium Decorated Carbon Nanotubes

PubMed Central

Colindres, Selene Capula; Aguir, Khalifa; Sodi, Felipe Cervantes; Vargas, Luis Villa; Moncayo Salazar, José A.; Febles, Vicente Garibay

2014-01-01

Multiwall carbon nanotubes (MWCNTs) were easily and efficiently decorated with Pd nanoparticles through a vapor-phase impregnation-decomposition method starting from palladium acetylacetonates. The sensor device consisted on a film of sensitive material (MWCNTs-Pd) deposited by drop coating on platinum interdigitated electrodes on a SiO2 substrate. The sensor exhibited a resistance change to ozone (O3) with a response time of 60 s at different temperatures and the capability of detecting concentrations up to 20 ppb. The sensor shows the best response when exposed to O3 at 120 °C. The device shows a very reproducible sensor performance, with high repeatability, full recovery and efficient response. PMID:24736133

Sol–gel synthesis of MCM-41 silicas and selective vapor-phase modification of their surface

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

Roik, N.V., E-mail: roik_nadya@ukr.net; Belyakova, L.A.

2013-11-15

Silica particles with uniform hexagonal mesopore architecture were synthesized by template directed sol–gel condensation of tetraethoxysilane or mixture of tetraethoxysilane and (3-chloropropyl)triethoxysilane in a water–ethanol–ammonia solution. Selective functionalization of exterior surface of parent materials was carried out by postsynthetic treatment of template-filled MCM-41 and Cl-MCM-41 with vapors of (3-chloropropyl)triethoxysilane and 1,2-ethylenediamine in vacuum. The chemical composition of obtained mesoporous silicas was estimated by IR spectroscopy and chemical analysis of surface products of reactions. Characteristics of porous structure of resulting materials were determined from the data of X-ray, low-temperature nitrogen ad-desorption and transmission electron microscopy measurements. Obtained results confirm invariability ofmore » highly ordered mesoporous structure of MCM-41 and Cl-MCM-41 after their selective postsynthetic modification in vapor phase. It was proved that proposed method of vapor-phase functionalization of template-filled starting materials is not accompanied by dissolution of the template and chemical modification of pores surface. This provides preferential localization of grafted functional groups onto the exterior surface of mesoporous silicas. - Graphical abstract: Sol–gel synthesis and postsynthetic chemical modification of template-filled MCM-41 and Cl-MCM-41 with (3-chloropropyl)triethoxysilane and 1,2-ethylenediamine in vapor phase. Display Omitted - Highlights: • Synthesis of MCM-41 silica by template directed sol–gel condensation. • Selective vapor-phase functionalization of template-filled silica particles. • Preferential localization of grafted groups onto the exterior surface of mesoporous silicas.« less

An immersed boundary method for two-phase fluids and gels and the swimming of Caenorhabditis elegans through viscoelastic fluids

PubMed Central

Lee, Pilhwa; Wolgemuth, Charles W.

2016-01-01

The swimming of microorganisms typically involves the undulation or rotation of thin, filamentary objects in a fluid or other medium. Swimming in Newtonian fluids has been examined extensively, and only recently have investigations into microorganism swimming through non-Newtonian fluids and gels been explored. The equations that govern these more complex media are often nonlinear and require computational algorithms to study moderate to large amplitude motions of the swimmer. Here, we develop an immersed boundary method for handling fluid-structure interactions in a general two-phase medium, where one phase is a Newtonian fluid and the other phase is viscoelastic (e.g., a polymer melt or network). We use this algorithm to investigate the swimming of an undulating, filamentary swimmer in 2D (i.e., a sheet). A novel aspect of our method is that it allows one to specify how forces produced by the swimmer are distributed between the two phases of the fluid. The algorithm is validated by comparing theoretical predictions for small amplitude swimming in gels and viscoelastic fluids. We show how the swimming velocity depends on material parameters of the fluid and the interaction between the fluid and swimmer. In addition, we simulate the swimming of Caenorhabditis elegans in viscoelastic fluids and find good agreement between the swimming speeds and fluid flows in our simulations and previous experimental measurements. These results suggest that our methodology provides an accurate means for exploring the physics of swimming through non-Newtonian fluids and gels. PMID:26858520

Phase equilibria in the lysozyme-ammonium sulfate-water system.

PubMed

Moretti, J J; Sandler, S I; Lenhoff, A M

2000-12-05

Ternary phase diagrams were measured for lysozyme in ammonium sulfate solutions at pH values of 4 and 8. Lysozyme, ammonium sulfate, and water mass fractions were assayed independently by UV spectroscopy, barium chloride titration, and lyophilization respectively, with mass balances satisfied to within 1%. Protein crystals, flocs, and gels were obtained in different regions of the phase diagrams, and in some cases growth of crystals from the gel phase or from the supernatant after floc removal was observed. These observations, as well as a discontinuity in protein solubility between amorphous floc precipitate and crystal phases, indicate that the crystal phase is the true equilibrium state. The ammonium sulfate was generally found to partition unequally between the supernatant and the dense phase, in disagreement with an assumption often made in protein phase equilibrium studies. The results demonstrate the potential richness of protein phase diagrams as well as the uncertainties resulting from slow equilibration. Copyright 2000 John Wiley & Sons, Inc.

Transportation of single cell and microbubbles by phase-shift introduced to standing leaky surface acoustic waves

PubMed Central

Meng, Long; Cai, Feiyan; Zhang, Zidong; Niu, Lili; Jin, Qiaofeng; Yan, Fei; Wu, Junru; Wang, Zhanhui; Zheng, Hairong

2011-01-01

A microfluidic device was developed to precisely transport a single cell or multiple microbubbles by introducing phase-shifts to a standing leaky surface acoustic wave (SLSAW). The device consists of a polydimethyl-siloxane (PDMS) microchannel and two phase-tunable interdigital transducers (IDTs) for the generation of the relative phase for the pair of surface acoustic waves (SAW) propagating along the opposite directions forming a standing wave. When the SAW contacts the fluid medium inside the microchannel, some of SAW energy is coupled to the fluid and the SAW becomes the leaky surface wave. By modulating the relative phase between two IDTs, the positions of pressure nodes of the SLSAW in the microchannel change linearly resulting in the transportation of a single cell or microbubbles. The results also reveal that there is a good linear relationship between the relative phase and the displacement of a single cell or microbubbles. Furthermore, the single cell and the microbubbles can be transported over a predetermined distance continuously until they reach the targeted locations. This technique has its distinct advantages, such as precise position-manipulation, simple to implement, miniature size, and noninvasive character, which may provide an effective method for the position-manipulation of a single cell and microbubbles in many biological and biomedical applications. PMID:22662056

Single DNA molecules on freestanding and supported cationic lipid bilayers: diverse conformational dynamics controlled by the local bilayer properties

NASA Astrophysics Data System (ADS)

Herold, Christoph; Schwille, Petra; Petrov, Eugene P.

2016-02-01

We present experimental results on the interaction of DNA macromolecules with cationic lipid membranes with different properties, including freestanding membranes in the fluid and gel state, and supported lipid membranes in the fluid state and under conditions of fluid-gel phase coexistence. We observe diverse conformational dynamics of membrane-bound DNA molecules controlled by the local properties of the lipid bilayer. In case of fluid-state freestanding lipid membranes, the behaviour of DNA on the membrane is controlled by the membrane charge density: whereas DNA bound to weakly charged membranes predominantly behaves as a 2D random coil, an increase in the membrane charge density leads to membrane-driven irreversible DNA collapse and formation of subresolution-sized DNA globules. On the other hand, electrostatic binding of DNA macromolecules to gel-state freestanding membranes leads to completely arrested diffusion and conformational dynamics of membrane-adsorbed DNA. A drastically different picture is observed in case of DNA interaction with supported cationic lipid bilayers: When the supported bilayer is in the fluid state, membrane-bound DNA molecules undergo 2D translational Brownian motion and conformational fluctuations, irrespectively of the charge density of the supported bilayer. At the same time, when the supported cationic membrane shows fluid-gel phase coexistence, membrane-bound DNA molecules are strongly attracted to micrometre-sized gel-phase domains enriched with the cationic lipid, which results in 2D compaction of the membrane-bound macromolecules. This DNA compaction, however, is fully reversible, and disappears as soon as the membrane is heated above the fluid-gel coexistence. We also discuss possible biological implications of our experimental findings.

Computational Design Tool for the Synthesis and Optimization of Gel Formulations (SOGeF)

DTIC Science & Technology

2009-01-01

ACCOMPLISHMENTS 2.1 Phase I Technical Objectives TIle primary technical objective of the Phase I program was the development of a model(s) to describe the...Figure 37: Storage Modulus G’, Loss Modulus G", and Stress vs. Strain. Yield Stress ~460Pa. (Tri-ethylamine 11% Cabosil) The primary detenninant of...GUI The primary objective of this task was to design and implement a graphical user interface (GUI) for the NN algorithms and gel database files. The

A Randomized, Double-blind, Vehicle-controlled Trial of Luliconazole Cream 1% in the Treatment of Interdigital Tinea Pedis

PubMed Central

Vlahovic, Tracey C.; Gold, Michael H.; Parish, Lawrence Charles; Korotzer, Andrew

2014-01-01

Objective: To evaluate the efficacy and safety of luliconazole cream 1% applied once daily for 14 days in patients with interdigital tinea pedis. Design: Multicenter, randomized, double-blind, parallel-group, vehicle-controlled study. Setting: Private dermatology clinics and clinical research centers in the United States and Central America. Participants: Three hundred twenty-two male and female patients ≥12 years of age diagnosed with interdigital tinea pedis. Measurements: Complete clearance (i.e., clinical and mycological cure), effective treatment, and fungal culture and susceptibility. Results: At study Day 42, complete clearance was obtained by a larger percentage (14.0% [15/107] vs. 2.8% [3/107]; p<0.001) of patients treated with luliconazole cream 1% compared with vehicle. Also at Day 42, more luliconazole-treated patients compared with vehicle-treated patients obtained effective treatment (32.7% vs. 15.0%), clinical cure (15.0% vs. 3.7%), and mycologic cure (56.1% vs. 27.1%). Erythema, scaling, and pruritus scores were lower for the luliconazole cream 1% group compared with vehicle on Day 14, Day 28, and Day 42. For all species and the same isolates, the MIC50/90 for luliconazole cream 1% was 6- to 12-fold lower than for other agents tested. No patients discontinued treatment because of a treatment-emergent adverse event. Conclusion: Luliconazole cream 1% was safe and well-tolerated and demonstrated significantly greater efficacy than vehicle cream in patients with interdigital tinea pedis. PMID:25371767

A Randomized, Double-blind, Vehicle-controlled Trial of Luliconazole Cream 1% in the Treatment of Interdigital Tinea Pedis.

PubMed

Draelos, Zoe Diana; Vlahovic, Tracey C; Gold, Michael H; Parish, Lawrence Charles; Korotzer, Andrew

2014-10-01

To evaluate the efficacy and safety of luliconazole cream 1% applied once daily for 14 days in patients with interdigital tinea pedis. Multicenter, randomized, double-blind, parallel-group, vehicle-controlled study. Private dermatology clinics and clinical research centers in the United States and Central America. Three hundred twenty-two male and female patients ≥12 years of age diagnosed with interdigital tinea pedis. Complete clearance (i.e., clinical and mycological cure), effective treatment, and fungal culture and susceptibility. At study Day 42, complete clearance was obtained by a larger percentage (14.0% [15/107] vs. 2.8% [3/107]; p<0.001) of patients treated with luliconazole cream 1% compared with vehicle. Also at Day 42, more luliconazole-treated patients compared with vehicle-treated patients obtained effective treatment (32.7% vs. 15.0%), clinical cure (15.0% vs. 3.7%), and mycologic cure (56.1% vs. 27.1%). Erythema, scaling, and pruritus scores were lower for the luliconazole cream 1% group compared with vehicle on Day 14, Day 28, and Day 42. For all species and the same isolates, the MIC50/90 for luliconazole cream 1% was 6- to 12-fold lower than for other agents tested. No patients discontinued treatment because of a treatment-emergent adverse event. Luliconazole cream 1% was safe and well-tolerated and demonstrated significantly greater efficacy than vehicle cream in patients with interdigital tinea pedis.

Yield of reversible colloidal gels during flow start-up: release from kinetic arrest.

PubMed

Johnson, Lilian C; Landrum, Benjamin J; Zia, Roseanna N

2018-06-05

Yield of colloidal gels during start-up of shear flow is characterized by an overshoot in shear stress that accompanies changes in network structure. Prior studies of yield of reversible colloidal gels undergoing strong flow model the overshoot as the point at which network rupture permits fluidization. However, yield under weak flow, which is of interest in many biological and industrial fluids shows no such disintegration. The mechanics of reversible gels are influenced by bond strength and durability, where ongoing rupture and re-formation impart aging that deepens kinetic arrest [Zia et al., J. Rheol., 2014, 58, 1121], suggesting that yield be viewed as release from kinetic arrest. To explore this idea, we study reversible colloidal gels during start-up of shear flow via dynamic simulation, connecting rheological yield to detailed measurements of structure, bond dynamics, and potential energy. We find that pre-yield stress grows temporally with the changing roles of microscopic transport processes: early time behavior is set by Brownian diffusion; later, advective displacements permit relative particle motion that stretches bonds and stores energy. Stress accumulates in stretched, oriented bonds until yield, which is a tipping point to energy release, and is passed with a fully intact network, where the loss of very few bonds enables relaxation of many, easing glassy arrest. This is immediately followed by a reversal to growth in potential energy during bulk plastic deformation and condensation into larger particle domains, supporting the view that yield is an activated release from kinetic arrest. The continued condensation of dense domains and shrinkage of network surfaces, along with a decrease in the potential energy, permit the gel to evolve toward more complete phase separation, supporting our view that yield of weakly sheared gels is a 'non-equilibrium phase transition'. Our findings may be particularly useful for industrial or other coatings, where weak, slow application via shear may lead to phase separation, inhibiting smooth distribution.

Structure of gels layers with cells

NASA Astrophysics Data System (ADS)

Pokusaev, B. G.; Karlov, S. P.; Vyazmin, A. V.; Nekrasov, D. A.; Zakharov, N. S.; Khramtsov, D. P.; Skladnev, D. A.; Tyupa, D. V.

2017-11-01

The structure of two-layer agarose gels containing yeast cells is investigated experimentally by spectrometry, to shed a light on the theoretical foundations for the development of bioreactors by the method of 3D bioprinting. Due to division, cells overcome the layer of the dispersion phase separating successively applied layers of the agarose gel. However a gel layer of 100 μm thick with a high concentration of silver nanoparticles completely excludes the infiltration of yeast cells through it. A special sort of agarose is suggested where the concentration of silver nanoparticles formed by cells from salt of silver can serve as an indicator of the state of the yeast cells in the volume of the gel.

Development of pharmaceutical clear gel based on Peceol®, lecithin, ethanol and water: Physicochemical characterization and stability study.

PubMed

Mouri, Abdelkader; Diat, Olivier; El Ghzaoui, Abdeslam; Ly, Isabelle; Dorandeu, Christophe; Maurel, Jean Claude; Devoisselle, Jean-Marie; Legrand, Philippe

2015-11-01

The phase behavior of the four-components Peceol®/lecithin/ethanol/water system has been studied in a part of the phase diagram poor in water and varying the lecithin/Peceol® ratio. Using several complementary techniques such as Karl Fischer titration, rheology, polarized microscopy and SAXS measurements several nanostructures of the complex systems were identified. W/O microemulsion (L2) as well as an inverted hexagonal (H2) liquid-crystal phase were studied. The analysis of the different phase transitions allows us to understand the effect of lecithin on the water solubilization efficiency of this clear gel and to show its pharmaceutical interest among lecithin organogels. Copyright © 2015 Elsevier Inc. All rights reserved.

Application of polyacrylamide gel as a new membrane in electromembrane extraction for the quantification of basic drugs in breast milk and wastewater samples.

PubMed

Asadi, Sakine; Tabani, Hadi; Nojavan, Saeed

2018-03-20

Introducing new membranes with green chemistry approach seems to be a great challenge for the development of a practical method in separation science. In this regard, for the first time, polyacrylamide gel as a new membrane in electromembrane extraction (EME) was used for the extraction of three model basic drugs (pseudoephedrine (PSE), lidocaine (LID), and propranolol (PRO)), followed by HPLC-UV. In comparison with conventional EME, in this method neither organic solvent nor carrier agents were used for extraction of mentioned drugs. Different variables for fabrication of polyacrylamide gel and extraction process were evaluated. Polyacrylamide gel (containing 12% (w/v) acrylamide, and 3.0% (w/w) bisacrylamide) with 2 mm thickness at pH = 1.5 was fabricated as membrane. The drugs were extracted from aqueous samples, through a polyacrylamide gel membrane, to an aqueous acceptor phase on membrane. Under the optimized extraction conditions (Voltage: 85 V, extraction time: 28 min, acceptor phase's pH: 4.0, and donor phase's pH: 7.0) limits of quantification and detection were in the ranges of 1.0-20.0 ng mL -1 and 0.3-6.0 ng mL -1 , respectively. Applying the proposed method to determine and quantify intended drugs in breast milk, and wastewater samples have revealed acceptable results. Copyright © 2018 Elsevier B.V. All rights reserved.

Novel microemulsion-based gels for topical delivery of indomethacin: Formulation, physicochemical properties and in vitro drug release studies.

PubMed

Froelich, Anna; Osmałek, Tomasz; Snela, Agnieszka; Kunstman, Paweł; Jadach, Barbara; Olejniczak, Marta; Roszak, Grzegorz; Białas, Wojciech

2017-12-01

Microemulsion-based semisolid systems may be considered as an interesting alternative to the traditional dosage forms applied in topical drug delivery. Mechanical properties of topical products are important both in terms of application and dosage form effectiveness. In this study we designed and evaluated novel microemulsion-based gels with indomethacin and analyzed the factors affecting their mechanical characteristics and drug release. The impact of the microemulsion composition on the extent of isotropic region was investigated with the use of pseudoternary phase diagrams. Selected microemulsions were analyzed in terms of electrical conductivity and surface tension in order to determine the microemulsion type. Microemulsions were transformed into polymer-based gels and subjected to rheological and textural studies. Finally, the indomethacin release from the analyzed gels was studied and compared to commercially available product. The extent of isotropic domain in pseudoternary phase diagrams seems to be dependent on the polarity of the oil phase. The surface tension and conductivity monitored as a function of water content in microemulsion systems revealed possible structural transformations from w/o through bicontinuous systems into o/w. The mechanical properties of semisolid microemulsion-based systems depended on the composition of surface active agents and the drug presence. The drug release profiles observed in the case of the investigated gels differed from those recorded for the commercially available product which was most probably caused by the different structure of both systems. Copyright © 2017 Elsevier Inc. All rights reserved.

“Tell Juliana”: Acceptability of the Candidate Microbicide VivaGel® and Two Placebo Gels Among Ethnically Diverse, Sexually Active Young Women Participating in a Phase 1 Microbicide Study

PubMed Central

Giguere, Rebecca; Dolezal, Curtis; Chen, Beatrice A.; Kahn, Jessica; Zimet, Greg; Mabragaña, Marina; Leu, Cheng-Shiun; McGowan, Ian

2011-01-01

This study assessed acceptability of the candidate microbicide VivaGel® and two placebo gels among 61 sexually active young US and Puerto Rican women at three sites. Participants were randomly assigned to use one of the gels twice per day for 14 days. At trial completion, 59% of the women in the VivaGel® group reported being likely to use the gel in the future, whereas 23% were unlikely to use it and 18% were undecided. Participants reported problems with all three gels, including the “universal” placebo containing hydroxyethyl cellulose (HEC). The most frequent complaints were leakage, interference with sexual behavior, and decreased sexual satisfaction. Some of the complaints are not new but remain unresolved. Women’s perceived risk of HIV infection may determine whether the gels are used. Users also may want a choice of viscosity. Poor acceptability of vaginal microbicide formulations may result in poor adherence to gel use during efficacy trials and compromise validity of results. PMID:21863338

Multistable Phase-Retardation Plate Based on Gelator-Doped Liquid Crystals

NASA Astrophysics Data System (ADS)

Ying-Guey Fuh, Andy; Chiang, Jou-Ting; Chien, Yu-Shein; Chang, Chih-Juang; Lin, Hui-Chi

2012-07-01

This work demonstrates a multistable, large phase-retardation plate using gelator-doped liquid crystals (LCs). Multistability is achieved by forming a rubbery LC gel at room temperature. Experimentally, the phase retardation (PR) of an LC-gel film can be varied and fixed by the thermoreversible association and dissociation of the gelator molecules. The PR of the LC plate ranging from 0.3-3.7π can be electrically controllable within 10 V. Half-wave and quarter-wave LC plates were also produced at applied voltages of 3.5 and 6.3 V, respectively. Their properties were examined and found to be stable.

Multistable Phase-Retardation Plate Based on Gelator-Doped Liquid Crystals

NASA Astrophysics Data System (ADS)

Fuh, Andy Ying-Guey; Chiang, Jou-Ting; Chien, Yu-Shein; Chang, Chih-Juang; Lin, Hui-Chi

2012-07-01

This work demonstrates a multistable, large phase-retardation plate using gelator-doped liquid crystals (LCs). Multistability is achieved by forming a rubbery LC gel at room temperature. Experimentally, the phase retardation (PR) of an LC-gel film can be varied and fixed by the thermoreversible association and dissociation of the gelator molecules. The PR of the LC plate ranging from 0.3--3.7π can be electrically controllable within 10 V. Half-wave and quarter-wave LC plates were also produced at applied voltages of 3.5 and 6.3 V, respectively. Their properties were examined and found to be stable.

External and Intraparticle Diffusion of Coumarin 102 with Surfactant in the ODS-silica Gel/water System by Single Microparticle Injection and Confocal Fluorescence Microspectroscopy.

PubMed

Nakatani, Kiyoharu; Matsuta, Emi

2015-01-01

The release mechanism of coumarin 102 from a single ODS-silica gel microparticle into the water phase in the presence of Triton X-100 was investigated by confocal fluorescence microspectroscopy combined with the single microparticle injection technique. The release rate significantly depended on the Triton X-100 concentration in the water phase and was not limited by diffusion in the pores of the microparticle. The release rate constant was inversely proportional to the microparticle radius squared, indicating that the rate-determining step is the external diffusion between the microparticle and the water phase.

Study of kinetic desorption rate constant in fish muscle and agarose gel model using solid phase microextraction coupled with liquid chromatography with tandem mass spectrometry.

PubMed

Togunde, Oluranti Paul; Oakes, Ken; Servos, Mark; Pawliszyn, Janusz

2012-09-12

This study aims to use solid phase microextraction (SPME), a simple tool to investigate diffusion rate (time) constant of selected pharmaceuticals in gel and fish muscle by comparing desorption rate of diffusion of the drugs in both agarose gel prepared with phosphate-buffered saline (PBS; pH 7.4) and fish muscle. The gel concentration (agarose gel model) that could be used to simulate tissue matrix (fish muscle) for free diffusion of drugs under in vitro and in vivo conditions was determined to model mass transfer phenomena between fibre polymer coating and environmental matrix such that partition coefficients and desorption time constant (diffusion coefficient) can be determined. SPME procedure involves preloading the extraction phase (fibre) with the standards from spiked PBS for 1h via direct extraction. Subsequently, the preloaded fibre is introduced to the sample such fish or agarose gel for specified time ranging from 0.5 to 60 h. Then, fibre is removed at specified time and desorbed in 100 μL of desorption solution (acetonitrile: water 1:1) for 90 min under agitation speed of 1000 rpm. The samples extract were immediately injected to the instrument and analysed using liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS). The limit of detection of the method in gel and fish muscle was 0.01-0.07 ng mL(-1) and 0.07-0.34 ng g(-1), respectively, while the limit quantification was 0.10-0.20 ng mL(-1) in gel samples and 0.40-0.97 ng g(-1) in fish sample. The reproducibility of the method was good (5-15% RSD). The results suggest that kinetics of desorption of the compounds in fish tissue and different viscosity of gel can be determined using desorption time constant. In this study, desorption time constant which is directly related to desorption rate (diffusion kinetics) of selected drugs from the fibre to the gel matrix is faster as the viscosity of the gel matrix reduces from 2% (w/v) to 0.8% (w/v). As the concentration of gel reduces, viscosity of the gel will be reduced therefore allowing faster diffusion which invariably affect desorption time constant. Also, desorption time constant of model drugs in the fish muscle and 0.8-0.9% (w/v) gel model are similar based on free diffusion of studied compounds. In addition, in vitro and in vivo desorption time constant comparison shows that desorption time constant in an in vivo system (live fish muscle) is generally higher than an in vitro system (dead fish muscle) except for sertraline and nordiazepam. This study demonstrates SPME as a simple investigative tool to understand kinetics of desorption in an in vivo system with a goal to measure desorption rate of pharmaceuticals in fish. Copyright © 2011 Elsevier B.V. All rights reserved.

Sol/Gel Processing Techniques for Glass Matrix Composites.

DTIC Science & Technology

1987-11-01

silica alkoxide gels were also produced by an initial partial hydrolysis of TEOS. ,. After an aging period of 18-24 hrs. titanium (IV) isopropoxide ...preparation of these materials is the large difference in hydrolysis rate for titanium versus silica alkoxides. Thus, the tendency towards phase separation in...ethanol solution (Ref. 6-9). After an aging time, the more reactive titanium alkoxide is added. This solution gels quickly and is ready to be further

Sol-gel titania-coated needles for solid phase dynamic extraction-GC/MS analysis of desomorphine and desocodeine.

PubMed

Su, Chi-Ju; Srimurugan, Sankarewaran; Chen, Chinpiao; Shu, Hun-Chi

2011-01-01

Novel sol-gel titania film coated needles for solid-phase dynamic extraction (SPDE)-GC/MS analysis of desomorphine and desocodeine are described. The high thermal stability of titania film permits efficient extraction and analysis of poorly volatile opiate drugs. The influences of sol-gel reaction time, coating layer, extraction and desorption time and temperature on the SPDE needle performance were investigated. The deuterium labeled internal standard was introduced either during the extraction of analyte or directly injected to GC after the extraction process. The latter method was shown to be more sensitive for the analysis of water and urine samples containing opiate drugs. The proposed conditions provided a wide linear range (from 5-5000 ppb), and satisfactory linearity, with R(2) values from 0.9958 to 0.9999, and prominent sensitivity, LOQs (1.0-5.0 ng/g). The sol-gel titania film coated needle with SPDE-GC/MS will be a promising technique for desomorphine and desocodeine analysis in urine.

Preconcentration and Determination of Mefenamic Acid in Pharmaceutical and Biological Fluid Samples by Polymer-grafted Silica Gel Solid-phase Extraction Following High Performance Liquid Chromatography

PubMed Central

Bagheri Sadeghi, Hayedeh; Panahi, Homayon Ahmad; Mahabadi, Mahsa; Moniri, Elham

2015-01-01

Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) that has analgesic, anti-infammatory and antipyretic actions. It is used to relieve mild to moderate pains. Solid-phase extraction of mefenamic acid by a polymer grafted to silica gel is reported. Poly allyl glycidyl ether/iminodiacetic acid-co-N, N-dimethylacrylamide was synthesized and grafted to silica gel and was used as an adsorbent for extraction of trace mefenamic acid in pharmaceutical and biological samples. Different factors affecting the extraction method were investigated and optimum conditions were obtained. The optimum pH value for sorption of mefenamic acid was 4.0. The sorption capacity of grafted adsorbent was 7.0 mg/g. The best eluent solvent was found to be trifluoroacetic acid-acetic acid in methanol with a recovery of 99.6%. The equilibrium adsorption data of mefenamic acid by grafted silica gel was analyzed by Langmuir model. The conformation of obtained data to Langmuir isotherm model reveals the homogeneous binding sites of grafted silica gel surface. Kinetic study of the mefenamic acid sorption by grafted silica gel indicates the good accessibility of the active sites in the grafted polymer. The sorption rate of the investigated mefenamic acid on the grafted silica gel was less than 5 min. This novel synthesized adsorbent can be successfully applied for the extraction of trace mefenamic acid in human plasma, urine and pharmaceutical samples. PMID:26330865

Microwave dielectric properties of BNT-BT0.08 thin films prepared by sol-gel technique

NASA Astrophysics Data System (ADS)

Huitema, L.; Cernea, M.; Crunteanu, A.; Trupina, L.; Nedelcu, L.; Banciu, M. G.; Ghalem, A.; Rammal, M.; Madrangeas, V.; Passerieux, D.; Dutheil, P.; Dumas-Bouchiat, F.; Marchet, P.; Champeaux, C.

2016-04-01

We report for the first time the microwave characterization of 0.92(Bi0.5Na0.5)TiO3-0.08BaTiO3 (BNT-BT0.08) ferroelectric thin films fabricated by the sol-gel method and integrated in both planar and out-of-plane tunable capacitors for agile high-frequency applications and particularly on the WiFi frequency band from 2.4 GHz to 2.49 GHz. The permittivity and loss tangent of the realized BNT-BT0.08 layers have been first measured by a resonant cavity method working at 12.5 GHz. Then, we integrated the ferroelectric material in planar inter-digitated capacitors (IDC) and in out-of-plane metal-insulator-metal (MIM) devices and investigated their specific properties (dielectric tunability and losses) on the whole 100 MHz-15 GHz frequency domain. The 3D finite-elements electromagnetic simulations of the IDC capacitances are fitting very well with their measured responses and confirm the dielectric properties determined with the cavity method. While IDCs are not exhibiting an optimal tunability, the MIM capacitor devices with optimized Ir/MgO(100) bottom electrodes demonstrate a high dielectric tunability, of 30% at 2.45 GHz under applied voltages as low as 10 V, and it is reaching 50% under 20 V voltage bias at the same frequency. These high-frequency properties of the MIM devices integrating the BNT-BT0.08 films, combining a high tunability under low applied voltages indicate a wide integration potential for tunable devices in the microwave domain and particularly at 2.45 GHz, corresponding to the widely used industrial, scientific, and medical frequency band.

Sol-gel synthesis and adsorption properties of mesoporous manganese oxide

NASA Astrophysics Data System (ADS)

Ivanets, A. I.; Kuznetsova, T. F.; Prozorovich, V. G.

2015-03-01

Sol-gel synthesis of mesoporous xerogels of manganese oxide with different phase compositions has been performed. The manganese oxide sols were obtained by redox reactions of potassium permanganate with hydrogen peroxide or manganese(II) chloride in aqueous solutions. The isotherms of the low-temperature adsorption-desorption of nitrogen with manganese oxide xerogels treated at 80, 200, 400, and 600°C were measured. The samples were studied by electron microscopy and thermal and XRD analysis. The phase transformation and the changes in the adsorption and capillary-condensation properties of manganese oxide were shown to depend on the sol synthesis conditions and the temperature of the thermal treatment of the gel. The X-ray amorphous samples heated at 80°C were shown to have low values of the specific surface; at higher temperatures, the xerogel crystallized into mixed phases with various compositions and its surface area increased at 200-400°C and decreased at 600°C.

Titanium dioxide nanoparticles: Impact of increasing ionic strength during synthesis, reflux, and hydrothermal aging

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

Isley, Sara L.; Jordan, David S.; Penn, R. Lee

2009-01-08

This work investigates the role of ionic strength during synthesis, reflux, and hydrothermal aging of sol-gel synthesized titanium dioxide. Research presented here uses X-ray diffraction data and Rietveld refinements to quantify anatase, brookite, and rutile phases as functions of synthetic and aging variables. In addition, the Scherrer equation is used to obtain average crystallite sizes for each phase quantified. Results presented in this work demonstrate that the most control over the sol-gel products can be obtained by modifying the pH during hydrolysis. In addition, while varying the ionic strength during reflux and hydrothermal aging can result in enhanced control overmore » the crystalline phase and crystallite size, the most control can be achieved by varying the ionic strength during synthesis. Finally, sol-gel synthesis at low pH (-0.6) and high-chloride concentration (3 M NaCl) produced a heterogeneous sample composed of nanocrystalline anatase (3.8 nm) and rutile (2.9 nm)« less

Efficient and Stable Photovoltaic Characteristics of Quasi-Solid State DSSC using Polymer Gel Electrolyte Based on Ionic Liquid in Organosiloxane Polymer Gels

NASA Astrophysics Data System (ADS)

Pujiarti, H.; Arsyad, W. S.; Shobih; Muliani, L.; Hidayat, R.

2018-04-01

Dye-Sensitized Solar Cell (DSSC) is still one of the promising solar cell types among the third generation of solar cells because of easiness of fabrication and variety of available materials. In this type of solar cell, the electrolyte is one of the important components for regenerating excited dyes and transporting electric charge carriers to the counter electrode. Indeed, the power conversion efficiency of DSSC can be then significantly affected by the chemical and physical properties of the electrolyte. The simplest electrolyte system of an I-/I3 - redox couple in an organic solvent, however, has some drawbacks due to corrosive properties, volatile and leakage problem. Use of solid phase or gel phase electrolyte may overcome those problems, but it is often considered to suppress the efficiency due to low ion diffusion. Here, we report the photovoltaic characteristics of DSSC using polymer gel electrolyte (PGE), which is composed of ionic liquid and an organosiloxane polymer gel. The better cell performance with power conversion efficiency of about 6% has been obtained by optimizing the mesoporous size of the TiO2 layer and the PGE viscosity.

Liposome retention in size exclusion chromatography

PubMed Central

Ruysschaert, Tristan; Marque, Audrey; Duteyrat, Jean-Luc; Lesieur, Sylviane; Winterhalter, Mathias; Fournier, Didier

2005-01-01

Background Size exclusion chromatography is the method of choice for separating free from liposome-encapsulated molecules. However, if the column is not presaturated with lipids this type of chromatography causes a significant loss of lipid material. To date, the mechanism of lipid retention is poorly understood. It has been speculated that lipid binds to the column material or the entire liposome is entrapped inside the void. Results Here we show that intact liposomes and their contents are retained in the exclusion gel. Retention depends on the pore size, the smaller the pores, the higher the retention. Retained liposomes are not tightly fixed to the beads and are slowly released from the gels upon direct or inverted eluent flow, long washing steps or column repacking. Further addition of free liposomes leads to the elution of part of the gel-trapped liposomes, showing that the retention is transitory. Trapping reversibility should be related to a mechanism of partitioning of the liposomes between the stationary phase, water-swelled polymeric gel, and the mobile aqueous phase. Conclusion Retention of liposomes by size exclusion gels is a dynamic and reversible process, which should be accounted for to control lipid loss and sample contamination during chromatography. PMID:15885140

Novel microemulsion-based gel formulation of tazarotene for therapy of acne.

PubMed

Patel, Mrunali Rashmin; Patel, Rashmin Bharatbhai; Parikh, Jolly R; Patel, Bharat G

2016-12-01

The objective of this study was to develop and evaluate a novel microemulsion based gel formulation containing tazarotene for targeted topical therapy of acne. Psudoternary phase diagrams were constructed to obtain the concentration range of oil, surfactant, and co-surfactant for microemulsion formation. The optimized microemulsion formulation containing 0.05% tazarotene was formulated by spontaneous microemulsification method consisting of 10% Labrafac CC, mixed emulsifiers 15% Labrasol-Cremophor-RH 40 (1:1), 15% Capmul MCM, and 60% distilled water (w/w) as an external phase. All plain and tazarotene-loaded microemulsions were clear and showed physicochemical parameters for desired topical delivery and stability. The permeation profiles of tazarotene through rat skin from optimized microemulsion formulation followed the Higuchi model for controlled permeation. Microemulsion-based gel was prepared by incorporating Carbopol®971P NF in optimized microemulsion formulation having suitable skin permeation rate and skin uptake. Microemulsion-based gel showed desired physicochemical parameters and demonstrated advantage over marketed formulation in improving the skin tolerability of tazarotene indicating its potential in improving its topical delivery. The developed microemulsion-based gel may be a potential drug delivery vehicle for targeted topical delivery of tazarotene in the treatment of acne.

Regenerated silica gel as stationary phase on vacuum column chromatography to purify temulawak’s extracts

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

Cahyono, Bambang; Maduwu, Ratna Dewi; Widayat,

Commercial silica gel only used once by many researchers and affected high cost for purification process, also less support the green chemistry program. This research focused in regeneration silica gel that used purification of temulawak’s extracts (Curcuma xanthorrhiza Roxb) by vacuum column chromatography. Sample extracts (contains 10.1195±0.5971% of curcuminoids) was purified by vacuum column chromatography (pressure: 45 kPa, column: 100mm on length and 16mm on diameter). Ethanol 96% and acetone were compared as eluent. The amount of solvent and yield of curcuminoids used as indicator purification. The silica gel was regenerated with heating in 600°C for 8 hours The silica gelsmore » were analyzed by IR spectroscopy and X-ray diffraction. Furthermore, regenerated silica gel was used as the stationary phase in vacuum column chromatography under the same conditions with the previous purification. All the purification experiments were performed in three repetitions. Based on regression equation, y=0.132x+0.0011 (r{sup 2}=0.9997) the yield of curcuminoids on purified products using ethanol as the eluent was improved 4.26% (to 14.3724±0.5749%) and by acetone was improved 3,03% (to 13.1450 ±0.6318%). The IR spectrum of both silica gel showed the same vibration profile and also there were three crystallinity peaks missing on its X-ray diffraction. Regenerated silica gel has the same performance with new silica gel in purification of temulawak’s extract: by ethanol has increased 4.08% (14.1947±0.7415%) and 2.93% (13.0447±0.4822) by acetone. In addition, all purification products showed similar TLC profiles. Purification using regenerated silica gel as the adsorbent on vacuum column chromatography has exactly same potential with the new silica gel.« less

HPTN 035 phase II/IIb randomised safety and effectiveness study of the vaginal microbicides BufferGel and 0.5% PRO 2000 for the prevention of sexually transmitted infections in women.

PubMed

Guffey, M Bradford; Richardson, Barbra; Husnik, Marla; Makanani, Bonus; Chilongozi, David; Yu, Elmer; Ramjee, Gita; Mgodi, Nyaradzo; Gomez, Kailazarid; Hillier, Sharon L; Karim, Salim Abdool

2014-08-01

To estimate the effectiveness of candidate microbicides BufferGel and 0.5% PRO 2000 Gel (P) (PRO 2000) for prevention of non-ulcerative sexually transmitted infections (STIs). Between 2005 and 2007, 3099 women were enrolled in HIV Prevention Trials Network (HPTN) protocol 035, a phase II/IIb evaluation of the safety and effectiveness of BufferGel and PRO 2000 for prevention of STIs, including Neisseria gonorrhoeae (NG), Chlamydia trachomatis (CT) and Trichomonas vaginalis (TV). Incidences of STIs were determined by study arm, and HRs of BufferGel and PRO 2000 versus placebo gel or no gel control groups were computed using discrete time Andersen-Gill proportional hazards model. The overall incidence rates were 1.6/100 person-years at risk (PYAR) for NG, 3.9/100 PYAR for CT and 15.3/100 PYAR for TV. For BufferGel versus placebo gel, HRs were 0.99 (95% CI 0.49 to 2.00), 1.00 (95% CI 0.64 to 1.57) and 0.95 (95% CI 0.71 to 1.25) for prevention of NG, CT and TV, respectively. For PRO 2000, HRs were 1.66 (95% CI 0.90 to 3.06), 1.16 (95% CI 0.76 to 1.79) and 1.18 (95% CI 0.90 to 1.53) for prevention of NG, CT and TV, respectively. The incidence of STIs was high during HIV Prevention Trials Network 035 despite provision of free condoms and comprehensive risk-reduction counselling, highlighting the need for effective STI prevention programmes in this population. Unfortunately, candidate microbicides BufferGel and PRO2000 had no protective effect against gonorrhoea, chlamydia or trichomoniasis. NCT00074425. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Anomalous piezoelectric properties of poly(vinylidene fluoride-trifluoroethylene)/ionic liquid gels

NASA Astrophysics Data System (ADS)

Fukagawa, Miki; Koshiba, Yasuko; Fukushima, Tatsuya; Morimoto, Masahiro; Ishida, Kenji

2018-04-01

Piezoelectric gels were prepared from low-volatile ionic liquid (IL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim][TFSI]) gels, and their structural, ferroelectric, and piezoelectric properties were investigated. Poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE)/IL gels were formed using thermally reversible physical gels. The structural characterization indicated that the P(VDF-TrFE) molecules in the gels predominantly formed a ferroelectric phase (Form I) of P(VDF-TrFE). Polarization switching peaks were clearly observed using a three-layer stacked device structure. The coercive field of the P(VDF-TrFE)/IL gels substantially decreased to 4-9 MV/m, and their remnant polarizations were maintained at 63-71 mC/m2, which is similar to that for typical solid-state P(VDF-TrFE). Finally, the P(VDF-TrFE)/IL gel films exhibited a piezoelectric response, and the highest piezoelectric coefficient was ˜300 pm/V at an applied voltage frequency of 4 kHz.

Sol-Gel Manufactured Energetic Materials

DOEpatents

Simpson, Randall L.; Lee, Ronald S.; Tillotson, Thomas M.; Hrubesh, Lawrence W.; Swansiger, Rosalind W.; Fox, Glenn A.

2005-05-17

Sol-gel chemistry is used for the preparation of energetic materials (explosives, propellants and pyrotechnics) with improved homogeneity, and/or which can be cast to near-net shape, and/or made into precision molding powders. The sol-gel method is a synthetic chemical process where reactive monomers are mixed into a solution, polymerization occurs leading to a highly cross-linked three dimensional solid network resulting in a gel. The energetic materials can be incorporated during the formation of the solution or during the gel stage of the process. The composition, pore, and primary particle sizes, gel time, surface areas, and density may be tailored and controlled by the solution chemistry. The gel is then dried using supercritical extraction to produce a highly porous low density aerogel or by controlled slow evaporation to produce a xerogel. Applying stress during the extraction phase can result in high density materials. Thus, the sol-gel method can be used for precision detonator explosive manufacturing as well as producing precision explosives, propellants, and pyrotechnics, along with high power composite energetic materials.

Sol-gel manufactured energetic materials

DOEpatents

Simpson, Randall L.; Lee, Ronald S.; Tillotson, Thomas M.; Hrubesh, Lawrence W.; Swansiger, Rosalind W.; Fox, Glenn A.

2003-12-23

Sol-gel chemistry is used for the preparation of energetic materials (explosives, propellants and pyrotechnics) with improved homogeneity, and/or which can be cast to near-net shape, and/or made into precision molding powders. The sol-gel method is a synthetic chemical process where reactive monomers are mixed into a solution, polymerization occurs leading to a highly cross-linked three dimensional solid network resulting in a gel. The energetic materials can be incorporated during the formation of the solution or during the gel stage of the process. The composition, pore, and primary particle sizes, gel time, surface areas, and density may be tailored and controlled by the solution chemistry. The gel is then dried using supercritical extraction to produce a highly porous low density aerogel or by controlled slow evaporation to produce a xerogel. Applying stress during the extraction phase can result in high density materials. Thus, the sol-gel method can be used for precision detonator explosive manufacturing as well as producing precision explosives, propellants, and pyrotechnics, along with high power composite energetic materials.

Continuous Non-Destructive Monitoring of Cell Health Using Impedance Based Interdigitated Electrode Structured Sensors

NASA Astrophysics Data System (ADS)

Paschero, Anna; McLoughlin, Eve; Moore, Eric

2011-06-01

This article examines some preliminary tests which were performed in order to evaluate the best electrode configuration (width and spacing) for cell culture analyses. Biochips packaged with indium tin oxide (ITO) interdigitated electrodes (IDEs) were used to perform impedance measurements on A549 cells cultured on the surface of the biochip. Several tests were carried out using a 10 mM solution of Sodium Chloride (NaCl), cell medium and the cell culture itself to characterize some of the configurations already fabricated in the facilities at Tyndall National Institute.

Multi-line triggering and interdigitated electrode structure for photoconductive semiconductor switches

DOEpatents

Mar, Alan [Albuquerque, NM; Zutavern, Fred J [Albuquerque, NM; Loubriel, Guillermo [Albuquerque, NM

2007-02-06

An improved photoconductive semiconductor switch comprises multiple-line optical triggering of multiple, high-current parallel filaments between the switch electrodes. The switch can also have a multi-gap, interdigitated electrode for the generation of additional parallel filaments. Multi-line triggering can increase the switch lifetime at high currents by increasing the number of current filaments and reducing the current density at the contact electrodes in a controlled manner. Furthermore, the improved switch can mitigate the degradation of switching conditions with increased number of firings of the switch.

Effect of sol temperature on structural, morphological and magnetic properties of PZT thin films on alumina substrate

NASA Astrophysics Data System (ADS)

Sreelalitha, K.; Thyagarajan, K.

2016-01-01

In the present study, we investigate the structural, morphological and magnetic properties of sol-gel spin-coated PZT thin films on alumina substrate. The morphotropic phase boundary (MPB) of PZT [Pb (Zr1-xTix)03] between the tetragonal and rhombohedral phases occurs at the Zr/Ti ratio of 52/48. At the MPB the physical properties of PZT are of far-reaching importance due to their possible crystalline phases. In this study Pb(Zr0.52Ti0.48)03 sols are prepared at room temperature and at 125 °C. The gels are coated onto alumina substrate using a spin-coating unit as two and three layers. The structural studies using XRD confirm the perovskite phase formation at an annealing temperature of 660 °C for both films. The structural parameter grain size, dislocation density, lattice parameters and strain were dependent on the sol temperature. The SEM morphology of the samples represents well-developed dense grain structure and thickness in micrometer ranges. The VSM analysis shows diamagnetic and ferromagnetic hysteresis loop. The ferromagnetism at low fields in PZT films is confirmed by studying the magnetic properties of powder made of the same gel. The effect of heat treatment on the gel preparation is observed on structural, morphological and magnetic properties of PZT thin films. The ferromagnetism in PZT can be attributed to oxygen vacancies. The squareness ratio of the films shows the application of the films as a high-density recording medium.

Interaction of curcumin with 1,2-dioctadecanoyl-sn-glycero-3-phosphocholine liposomes: Intercalation of rhamnolipids enhances membrane fluidity, permeability and stability of drug molecule.

PubMed

Moussa, Zeinab; Chebl, Mazhar; Patra, Digambara

2017-01-01

Stability of curcumin in neutral and alkaline buffer conditions has been a serious concern for its medicinal applications. We demonstrate that the stability of curucmin can be improved in 1,2-Dioctadecanoyl-sn-glycero-3-phosphocholine (DSPC) liposomes. Curcumin strongly partition into liquid crystalline phase compared to solid gel phase of DSPC liposomes. Variation of fluorescence intensity of curcumin associated with liposomes with temperature successfully determines phase transition temperature of DSPC liposomes. However, at higher molar ratio curcumin can influence phase transition temperature by intercalating into deep hydrophobic layer of liposomes and facilitating fusion of two membrane phases. Rhamnolipids (RLs) are recently being applied for various biomedical applications. Here, we have explored new insight on intercalation of rhamnolipids with DSPC liposomes. Intercalation of rhamnolipids exceptionally increases partition of curcumin into solid gel phase of DSPC liposomes, whereas this increase is moderate in liquid crystalline phase. Fluorescence quenching study establishes that permeability and fluidity of the DSPC liposomes are enhanced in the presence of RLs. Membrane permeability and fluidity can be improved further by increasing the percentage of RLs in DSPC liposomes. The phase transition temperature of DSPC liposomes decreases with increase in percentage of RLs in DSPC liposomes by encouraging fusion between solid gel and liquid crystalline phases. Intercalation of RLs is found to further boost stability of drug, curcumin, in DSPC liposomes. Thus, mixing RLs with DSPC liposomes could potentially serve as a good candidate for drug delivery application. Copyright © 2016 Elsevier B.V. All rights reserved.

Direct nanopatterning of 100 nm metal oxide periodic structures by Deep-UV immersion lithography.

PubMed

Stehlin, Fabrice; Bourgin, Yannick; Spangenberg, Arnaud; Jourlin, Yves; Parriaux, Olivier; Reynaud, Stéphanie; Wieder, Fernand; Soppera, Olivier

2012-11-15

Deep-UV lithography using high-efficiency phase mask has been developed to print 100 nm period grating on sol-gel based thin layer. High efficiency phase mask has been designed to produce a high-contrast interferogram (periodic fringes) under water immersion conditions for 244 nm laser. The demonstration has been applied to a new developed immersion-compatible sol-gel layer. A sol-gel photoresist prepared from zirconium alkoxides caped with methacrylic acids was developed to achieve 50 nm resolution in a single step exposure. The nanostructures can be thermally annealed into ZrO(2). Such route considerably simplifies the process for elaborating nanopatterned surfaces of transition metal oxides, and opens new routes for integrating materials of interest for applications in the field of photocatalysis, photovoltaic, optics, photonics or microelectronics.

Advancing the vesosome, a multifunctional drug delivery platform, toward applied in vivo testing

NASA Astrophysics Data System (ADS)

Wong, Benjamin J.

An optimal drug delivery vehicle should circulate long enough to reach the site of illness or disease, possess a large drug loading capacity, retain its contents over the course of treatment, and be able deliver its contents at a rate appropriate for maximum therapeutic benefit at the site of interest. The vesosome, a large lipid bilayer enclosing multiple, smaller liposomes, is our solution to addressing these needs. The external lipid bilayer offers a second barrier of protection for interior components and can also serve as the anchor for active targeting components. Furthermore, internal compartmentalization permits customization of separate environments for multiple therapeutics and release triggers. Previous work established the ability of the vesosome to retain its contents in vitro an order of magnitude longer than liposomes. To be viable in vivo, the vesosome must be functionalized for biocompatibility and tracking, and its synthetic procedure must be repeatable, reliable and result in a purified product. The vesosome was functionalized by introducing biocompatible polymers, such as poly(ethylene glycol) (PEG), and fluorescent dyes in their lipid-bound forms into the external membrane of the vesosome. The external vesosomal membrane is formed from large, flat lipid sheets in the interdigitated (L betaI) phase which, when heated, are used to encapsulate smaller drug-containing vesicles. Through X-Ray diffraction (XRD) and freeze-fracture transmission electron microscopy (FF-TEM), we established that the molar amounts of functionalized lipid required to label the vesosome for tracking and biocompatibility (˜5--7mol% total) did not prevent the formation of the interdigitated phase. Thus, functionalization of the external vesosome membrane can be achieved through functionalization of interdigitated sheets. For in vivo testing, functionalized vesosomes must be separated from unencapsulated vesicles and purification was performed using size exclusion chromatography (SEC) and centrifugation. Having functionalized vesosomes for biocompatibility, PEGylated vesosomes were examined in vitro and in vivo. The presence of surface-grafted PEG was shown to reduce vesosome-vesosome aggregation when exposed to human blood and the circulation half-life was determined to be approximately 2 hours. The evolution of biodistribution was examined by functionalizing the vesosome with a near-infrared dye for in vivo fluorescence imaging and preliminary active targeting experiments show increased vesosome presence at the targeted sites. Ex vivo organ analysis showed the ability of the vesosome to maintain structural integrity for at least 24 hours post-injection. By functionalizing the vesosome for biocompatibility and tracking through a repeatable and reliable synthesis, we have obtained a biocompatible vesosome. Through proof-of-concept live animal testing, we have demonstrated the feasibility of the vesosome as a single site, single dose, multi-therapeutic drug delivery vehicle.

Influence of metal electrodes on the response of humidity sensors coated with mesoporous silica

NASA Astrophysics Data System (ADS)

Bearzotti, Andrea

2008-01-01

Interesting effects of different metal electrodes on the behaviour of mesoporous based humidity sensors have been observed and studied by chemical characterization and electric measurements. The devices were prepared on passivated silicon slices utilizing an interdigitated structure as contacts. For comparison, the response of a device implemented on an alumina substrate has been reported. A block copolymer Pluronic F-127 has been used as the organic template and has been partially removed from the films by thermal calcination. A thin film mesoporous membrane has been deposited by dip-coating on the substrates in a sol-gel solution containing non-ionic block copolymers. Silica mesostructured films have been produced using an evaporation induced self-assembling process. The films were calcined at 150 °C to obtain the best performances in terms of stability, hysteresis and reproducibility of the response. The performance of the sensor has been found to be dependent on the film preparation method, the used electrodes and the substrate when exposed to different contents of relative humidity. Electrical characterization was performed under vacuum and dark conditions to investigate the properties of the materials in the absence of interfering chemicals, while the sensory properties were obtained in a controlled environment.

Phase equilibria and thermodynamic modeling of ethane and propane hydrates in porous silica gels.

PubMed

Seo, Yongwon; Lee, Seungmin; Cha, Inuk; Lee, Ju Dong; Lee, Huen

2009-04-23

In the present study, we examined the active role of porous silica gels when used as natural gas storage and transportation media. We adopted the dispersed water in silica gel pores to substantially enhance active surface for contacting and encaging gas molecules. We measured the three-phase hydrate (H)-water-rich liquid (L(W))-vapor (V) equilibria of C(2)H(6) and C(3)H(8) hydrates in 6.0, 15.0, 30.0, and 100.0 nm silica gel pores to investigate the effect of geometrical constraints on gas hydrate phase equilibria. At specified temperatures, the hydrate stability region is shifted to a higher pressure region depending on pore size when compared with those of bulk hydrates. Through application of the Gibbs-Thomson relationship to the experimental data, we determined the values for the C(2)H(6) hydrate-water and C(3)H(8) hydrate-water interfacial tensions to be 39 +/- 2 and 45 +/- 1 mJ/m(2), respectively. By using these values, the calculation values were in good agreement with the experimental ones. The overall results given in this study could also be quite useful in various fields, such as exploitation of natural gas hydrate in marine sediments and sequestration of carbon dioxide into the deep ocean.

Sol-Gel Synthesis of La(0.6)Sr(0.4)CoO(3-x) and Sm(0.5)Sr(0.5)CoO(3-x) Cathode Nanopowders for Solid Oxide Fuel Cells

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.; Wise, Brent

2011-01-01

Nanopowders of La(0.6)Sr(0.4)CoO(3-x) (LSC) and Sm(0.5)Sr(0.5)CoO(3-x) (SSC) compositions, which are being investigated as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFC) with La(Sr)Ga(Mg)O(3-x) (LSGM) as the electrolyte, were synthesized by low-temperature sol-gel method using metal nitrates and citric acid. Thermal decomposition of the citrate gels was followed by simultaneous DSC/TGA methods. Development of phases in the gels, on heat treatments at various temperatures, was monitored by x-ray diffraction. Solgel powders calcined at 550 to 1000 C consisted of a number of phases. Single perovskite phase La(0.6)Sr(0.4)CoO(3-x) or Sm(0.5)Sr(0.5)CoO(3-x) powders were obtained at 1200 and 1300 C, respectively. Morphological analysis of the powders calcined at various temperatures was done by scanning electron microscopy. The average particle size of the powders was approx.15 nm after 700 C calcinations and slowly increased to 70 to 100 nm after heat treatments at 1300 to 1400 C.

Structural and physical property study of sol-gel synthesized CoFe2-xHoxO4 nano ferrites

NASA Astrophysics Data System (ADS)

Patankar, K. K.; Ghone, D. M.; Mathe, V. L.; Kaushik, S. D.

2018-05-01

CoFe2-xHoxO4 (x = 0.00, 0.05, 0.10, 0.15, 0.20) ferrites were prepared by the suitably modified Sol-Gel technique. X-ray diffraction (XRD) analysis revealed that the substituted samples show phase pure formation till 10% substitution, which is far higher phase pure than the earlier reports. Upon further substitution an inevitable secondary phase of HoFeO3 along with the spinel phase despite regulating synthesis parameters in the sol-gel reaction route. These results are further corroborated more convincingly by room temperature neutron diffraction. Morphological features of the ferrites were studied by Scanning Electron Microscopy (SEM). The magnetic parameters viz. the saturation magnetization (Ms), coercivity (Hc) and remanence (Mr) were determined from room temperature isothermal magnetization. These parameters were found to decrease with increase in Ho substitution. The decrease in magnetization is analyzed in the light of exchange interactions between rare earth and transition metal ions. Magnetostriction measurements revealed interesting results and the presence of a secondary phase was found to be responsible for decreased measu-red magnetostriction values. The solubility limit of Ho in CoFe2O4 lattice is also reflected from the X-ray and neutron diffraction analysis and magnetostriction studies.

Self-consistent field theory of polymer-ionic molecule complexation.

PubMed

Nakamura, Issei; Shi, An-Chang

2010-05-21

A self-consistent field theory is developed for polymers that are capable of binding small ionic molecules (adsorbates). The polymer-ionic molecule association is described by Ising-like binding variables, C(i) ((a))(kDelta)(=0 or 1), whose average determines the number of adsorbed molecules, n(BI). Polymer gelation can occur through polymer-ionic molecule complexation in our model. For polymer-polymer cross-links through the ionic molecules, three types of solutions for n(BI) are obtained, depending on the equilibrium constant of single-ion binding. Spinodal lines calculated from the mean-field free energy exhibit closed-loop regions where the homogeneous phase becomes unstable. This phase instability is driven by the excluded-volume interaction due to the single occupancy of ion-binding sites on the polymers. Moreover, sol-gel transitions are examined using a critical degree of conversion. A gel phase is induced when the concentration of adsorbates is increased. At a higher concentration of the adsorbates, however, a re-entrance from a gel phase into a sol phase arises from the correlation between unoccupied and occupied ion-binding sites. The theory is applied to a model system, poly(vinyl alcohol) and borate ion in aqueous solution with sodium chloride. Good agreement between theory and experiment is obtained.

Measurement of effective piezoelectric coefficients of PZT thin films for energy harvesting application with interdigitated electrodes.

PubMed

Chidambaram, Nachiappan; Mazzalai, Andrea; Muralt, Paul

2012-08-01

Interdigitated electrode (IDE) systems with lead zirconate titanate (PZT) thin films play an increasingly important role for two reasons: first, such a configuration generates higher voltages than parallel plate capacitor-type electrode (PPE) structures, and second, the application of an electric field leads to a compressive stress component in addition to the overall stress state, unlike a PPE structure, which results in tensile stress component. Because ceramics tend to crack at relatively moderate tensile stresses, this means that IDEs have a lower risk of cracking than PPEs. For these reasons, IDE systems are ideal for energy harvesting of vibration energy, and for actuators. Systematic investigations of PZT films with IDE systems have not yet been undertaken. In this work, we present results on the evaluation of the in-plane piezoelectric coefficients with IDE systems. Additionally, we also propose a simple and measurable figure of merit (FOM) to analyze and evaluate the relevant piezoelectric parameter for harvesting efficiency without the need to fabricate the energy harvesting device. Idealized effective coefficients e(IDE) and h(IDE) are derived, showing its composite nature with about one-third contribution of the transverse effect, and about two-thirds contribution of the longitudinal effect in the case of a PZT film deposited on a (100)-oriented silicon wafer with the in-plane electric field along one of the <011> Si directions. Randomly oriented 1-μm-thick PZT 53/47 film deposited by a sol-gel technique, was evaluated and yielded an effective coefficient e(IDE) of 15 C·m(-2). Our FOM is the product between effective e and h coefficient representing twice the electrical energy density stored in the piezoelectric film per unit strain deformation (both for IDE and PPE systems). Assuming homogeneous fields between the fingers, and neglecting the contribution from below the electrode fingers, the FOM for IDE structures with larger electrode gap is derived to be twice as large as for PPE structures, for PZT-5H properties. The experiments yielded an FOM of the IDE structures of 1.25 × 10(10) J/m(3) and 14 mV/μ strain.

Characteristics of solidified products containing radioactive molten salt waste.

PubMed

Park, Hwan-Seo; Kim, In-Tae; Cho, Yong-Zun; Eun, Hee-Chul; Kim, Joon-Hyung

2007-11-01

The molten salt waste from a pyroprocess to recover uranium and transuranic elements is one of the problematic radioactive wastes to be solidified into a durable wasteform for its final disposal. By using a novel method, named as the GRSS (gel-route stabilization/solidification) method, a molten salt waste was treated to produce a unique wasteform. A borosilicate glass as a chemical binder dissolves the silicate compounds in the gel products to produce one amorphous phase while most of the phosphates are encapsulated by the vitrified phase. Also, Cs in the gel product is preferentially situated in the silicate phase, and it is vitrified into a glassy phase after a heat treatment. The Sr-containing phase is mainly phosphate compounds and encapsulated by the glassy phase. These phenomena could be identified by the static and dynamic leaching test that revealed a high leach resistance of radionuclides. The leach rates were about 10(-3) - 10(-2) g/m2 x day for Cs and 10(-4) - 10(-3) g/m2 x day for Sr, and the leached fractions of them were predicted to be 0.89% and 0.39% at 900 days, respectively. This paper describes the characteristics of a unique wasteform containing a molten salt waste and provides important information on a newly developed immobilization technology for salt wastes, the GRSS method.

Ferroelectric films of deuterated glycine phosphite: Structure and dielectric properties

NASA Astrophysics Data System (ADS)

Balashova, E. V.; Krichevtsov, B. B.; Svinarev, F. B.; Lemanov, V. V.

2013-05-01

Polycrystalline textured films of deuterated glycine phosphite consisting of single-crystal blocks with lateral dimensions ˜(50-100) μm and a thickness d ˜ (1-5) μm have been grown by evaporation on NdGaO3(100) and α-Al2O3 substrates with preliminarily deposited interdigitated electrodes, as well as on Al substrates. The c* ( Z) crystallographic axis in the blocks is normal to the film plane, and the a ( X) axis and the polar axis b ( Y) are oriented in the film plane. The temperature dependences of the capacitance of the structures measured with the interdigitated electrode system reveal a strong dielectric anomaly at the film transition to the ferroelectric state. The phase transition temperature T c depends on the degree of deuteration D of the glycine phosphite. The maximum value T c = 275 K obtained in the structures studied corresponds to a degree of deuteration of the glycine phosphite D ˜ 50%. The frequency behavior of the dielectric hysteresis loops in glycine phosphite films differs radically from that of the previously studied films of deuterated betaine phosphite, which evidences that polarization switching in these structures proceeds by different mechanisms. It has been that application of a dc bias to the electrodes changes the shape of the dielectric hysteresis loops and shifts them along the electric field axis. The shift of the loops depends on the sign, magnitude, and time of application of the bias. Possible mechanisms underlying the induced unipolarity are discussed.

Developing interface localized liquid dielectrophoresis for optical applications

NASA Astrophysics Data System (ADS)

McHale, Glen; Brown, Carl V.; Newton, Michael I.; Wells, Gary G.; Sampara, Naresh

2012-11-01

Electrowetting charges the solid-liquid interface to change the contact area of a droplet of a conducting liquid. It is a powerful technique used to create variable focus liquid lenses, electronic paper and other devices, but it depends upon ions within the liquid. Liquid dielectrophoresis (L-DEP) is a bulk force acting on the dipoles throughout a dielectric liquid and is not normally considered to be a localized effect acting at the interface between the liquid and a solid or other fluid. In this work, we show theoretically how non-uniform electric fields generated by interdigitated electrodes can effectively convert L-DEP into an interface localized form. We show that for droplets of sufficient thickness, the change in the cosine of the contact angle is proportional to the square of the applied voltage and so obeys a similar equation to that for electrowetting - this we call dielectrowetting. However, a major difference to electrowetting is that the strength of the effect is controlled by the electrode spacing and the liquid permittivity rather than the properties of an insulator in a sandwich structure. Experimentally, we show that that this dielectrowetting equation accurately describes the contact angle of a droplet of oil viewed across parallel interdigitated electrodes. Importantly, the induced spreading can be complete, such that contact angle saturation does not occur. We then show that for thin films, L-DEP can shape the liquid-air interface creating a spatially periodic wrinkle and that such a wrinkle can be used to create a voltage programmable phase diffraction grating.

A compact frequency tunable radio frequency phase shifter with patterned Py enabled transmission line

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

Rahman, B.M. Farid; Divan, Ralu; Rosenmann, Daniel

2015-01-01

A well designed frequency tunable phase shifter using patterned Py with different thickness has been demonstrated. Phase shifter is implemented with a slow wave coplanar wave guide (CPW)transmission line, where the signal line has alternate short narrow and wide sections. Py is patterned on the top of narrow section for high inductance density, and inter-digital capacitor is implemented in wide section for high capacitance density. Compared with phase shifter using regular CPW, the dimension of the developed phase shifter has been reduced from 14.86 mm to4.70 mm at 2 GHz. Phase shifter based on 100 nm and 200 nm thickmore » patterned Py with the same dimensions (14lm10lm) are implemented and investigated comprehensively. FMR frequency of 3.2 GHz and 3.6 GHz without any external magnetic field has been achieved for100 nm and 200 nm thick Py film, respectively. Thicker Py has increased inductance density from 1067.2 nH/m to 1193.2 nH/m while the center frequency of the phase shifter has been shifted to 1.80 GHz. Frequency tunability of the phase shifter has been also demonstrated withDC current. The phase shifter can provide 90phase shift continuously from 2 GHz to 1.80 GHz with DC current from 0 mA to 150 mA. The design concept has great potential in design arbitrary tunable RF components such as filters and couplers.« less

Mechano-switchable, luminescent gels derived from salts of a long-chained, fatty-acid gelator.

PubMed

Zhang, Mohan; Weiss, Richard G

2016-07-27

Stimulus-responsive molecular gel systems, based on metal salts of a luminescent gelator, 9,10-dioxooctadecanoic acid (DODA), are reported. These salts are structurally the simplest metallo-gelators of which we are aware that exhibit controllable mechano-responsive and luminescent properties. Aggregation is more favored by the metal salts than for DODA itself. However, gelation ability differs dramatically depending on the metal ion: whereas the salts with zinc(ii) and calcium(ii) are inefficient gelators, those with nickel(ii) and copper(ii) can gelate various aromatic liquids, alkanes, and long-chained alcohols. Unlike the DODA gels, no aggregation-induced shift in the positions of the emission spectra of the metal salts could be observed as the sols were transformed to their gel phases. Gels of both nickel(ii) and copper(ii) salts in benzonitrile are among the few known examples with crystalline networks and exhibiting thixotropic behavior. However, there are significant differences in their abilities to recover the initial viscoelastic properties. Structural data for the solid and gel states lead us to conclude that differences among the gelating abilities can be attributed principally to the specific nature of interactions of the salts at their head groups. They appear to control the mechanical and emissive properties of the gels as well as whether the initial aggregation of the salts in the sol phases will support the growth of 1D objects that are capable of maintaining strong contacts, leading to 3D networks and gel formation. Overall, the results provide a facile strategy for the design of luminescent materials with controllable mechano-responsiveness by modifying the metal ions within fibrillar assemblies.

Benzimidazole Based Aerogel Materials

NASA Technical Reports Server (NTRS)

Rhine, Wendell E. (Inventor); Mihalcik, David (Inventor)

2016-01-01

The present invention provides aerogel materials based on imidazoles and polyimidazoles. The polyimidazole based aerogel materials can be thermally stable up to 500 C or more, and can be carbonized to produce a carbon aerogel having a char yield of 60% or more, specifically 70% or more. The present invention also provides methods of producing polyimidazole based aerogel materials by reacting at least one monomer in a suitable solvent to form a polybenzimidazole gel precursor solution, casting the polybenzimidazole gel precursor solution into a fiber reinforcement phase, allowing the at least one gel precursor in the precursor solution to transition into a gel material, and drying the gel materials to remove at least a portion of the solvent, to obtain an polybenzimidazole-based aerogel material.

Coupled gel spreading and diffusive transport models describing microbicidal drug delivery

NASA Astrophysics Data System (ADS)

Funke, Claire; MacMillan, Kelsey; Ham, Anthony S.; Szeri, Andrew J.; Katz, David F.

2016-11-01

Gels are a drug delivery platform being evaluated for application of active pharmaceutical ingredients, termed microbicides, that act topically against infection by sexually transmitted HIV. Despite success in one Phase IIb trial of a vaginal gel delivering tenofovir, problems of user adherence to designed gel application regimen compromised results in two other trials. The microbicide field is responding to this issue by simultaneously analyzing behavioral determinants of adherence and pharmacological determinants of drug delivery. Central to both user adherence and mucosal drug delivery are gel properties (e.g. rheology) and applied volume. The specific problem to be solved here is to develop a model for how gel rheology and volume, interacting with loaded drug concentration, govern the transport of the microbicide drug tenofovir into the vaginal mucosa to its stromal layer. The analysis here builds upon our current understanding of vaginal gel deployment and drug delivery, incorporating key features of the gel's environment, fluid production and subsequent gel dilution, and vaginal wall elasticity. We consider the microbicide drug tenofovir as it is the most completely studied drug, in both in vitroand in vivostudies, for use in vaginal gel application. Our goal is to contribute to improved pharmacological understanding of gel functionality, providing a computational tool that can be used in future vaginal microbicide gel design.

Sol-gel synthesis of nanosized titanium dioxide at various pH of the initial solution

NASA Astrophysics Data System (ADS)

Dorosheva, I. B.; Valeeva, A. A.; Rempel, A. A.

2017-09-01

Titanium dioxide (TiO2) was synthesized by sol-gel method at different values of pH = 3, 7, 8, 9, or 10. X-ray phase analysis has shown that in an acid rout an anatase phase was crystallized, and in an alkaline rout an amorphous phase of TiO2 was achieved. After annealing for 4 hours at 350 °C, all samples was transformed in the anatase phase. The particle size in the different samples varies from 7 to 49 nm depending on the pH. The diffuse reflection spectra revealed a high value of the band gap in the range from 3.2 to 3.7 eV and its narrowing after annealing to the range from 3.2 to 3.5 eV.

Thermoresponsive Poly(Ionic Liquid)s in Aqueous Salt Solutions: Salting-Out Effect on Their Phase Behavior and Water Absorption/Desorption Properties.

PubMed

Okafuji, Akiyoshi; Kohno, Yuki; Ohno, Hiroyuki

2016-07-01

Here, a thermoresponsive phase behavior of polymerized ionic liquids (PILs) composed of poly([tri-n-alkyl(vinylbenzyl)phosphonium]chloride) (poly([Pnnn VB ]Cl) is reported, where n (the number of carbon atoms of an alkyl chain) = 4, 5, or 6 after mixing with aqueous sodium chloride solutions. Both monomeric [P555VB ]Cl and the resulting poly([P555VB ]Cl) linear homopolymer show a lower critical solution temperature (LCST)-type phase behavior in aq. NaCl solutions. The phase transition temperature of the PIL shifts to lower value by increasing concentration of NaCl. Also the swelling degree of cross-linked poly([P555VB ]Cl) gel decreases by increasing NaCl concentration, clearly suggesting the "salting-out" effect of NaCl results in a significant dehydration of the poly([P555VB ]Cl) gel. The absorbed water in the PIL gel is desorbed by moderate heating via the LCST behavior, and the absolute absorption/desorption amount is improved by copolymerization of [P555VB ]Cl with more hydrophilic [P444VB ]Cl monomer. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Alginate as immobilization matrix and stabilizing agent in a two-phase liquid system: application in lipase-catalysed reactions.

PubMed

Hertzberg, S; Kvittingen, L; Anthonsen, T; Skjåk-Braek, G

1992-01-01

Alginate was evaluated as an immobilization matrix for enzyme-catalyzed reactions in organic solvents. In contrast to most hydrogels, calcium alginate was found to be stable in a range of organic solvents and to retain the enzyme inside the gel matrix. In hydrophobic solvents, the alginate gel (greater than 95% water) thus provided a stable, two-phase liquid system. The lipase from Candida cylindracea, after immobilization in alginate beads, catalysed esterification and transesterification in n-hexane under both batch and continuous-flow conditions. The operational stability of the lipase was markedly enhanced by alginate entrapment. In the esterification of butanoic acid with n-butanol, better results were obtained in the typical hydrophilic calcium alginate beads than in less hydrophilic matrices. The effects of substrate concentration, matrix area, and polarity of the substrate alcohols and of the organic solvent on the esterification activity were examined. The transesterification of octyl 2-bromopropanoate with ethanol was less efficient than that of ethyl 2-bromopropanoate with octanol. By using the hydrophilic alginate gel as an immobilization matrix in combination with a mobile hydrophobic phase, a two-phase liquid system was achieved with definite advantages for a continuous, enzyme-catalysed process.

Erianthus arundinaceus HSP70 (EaHSP70) Acts as a Key Regulator in the Formation of Anisotropic Interdigitation in Sugarcane (Saccharum spp. hybrid) in Response to Drought Stress.

PubMed

Augustine, Sruthy Maria; Cherian, Anoop V; Syamaladevi, Divya P; Subramonian, N

2015-12-01

Plant growth during abiotic stress is a long sought-after trait especially in crop plants in the context of global warming and climate change. Previous studies on leaf epidermal cells have revealed that during normal growth and development, adjacent cells interdigitate anisotropically to form cell morphological patterns known as interlocking marginal lobes (IMLs), involving the cell wall-cell membrane-cortical actin continuum. IMLs are growth-associated cell morphological changes in which auxin-binding protein (ABP), Rho GTPases and actin are known to play important roles. In the present study, we investigated the formation of IMLs under drought stress and found that Erianthus arundinaceus, a drought-tolerant wild relative of sugarcane, develops such growth-related cell morphological patterns under drought stress. Using confocal microscopy, we showed an increasing trend in cortical F-actin intensity in drought-tolerant plants with increasing soil moisture stress. In order to check the role of drought tolerance-related genes in IML formation under soil moisture stress, we adopted a structural data mining strategy and identified indirect connections between the ABPs and heat shock proteins (HSPs). Initial experimental evidence for this connection comes from the high transcript levels of HSP70 observed in drought-stressed Erianthus, which developed anisotropic interdigitation, i.e. IMLs. Subsequently, by overexpressing the E. arundinaceus HSP70 gene (EaHSP70) in sugarcane (Saccharum spp. hybrid), we confirm the role of HSP70 in the formation of anisotropic interdigitation under drought stress. Taken together, our results suggest that EaHSP70 acts as a key regulator in the formation of anisotropic interdigitation in drought-tolerant plants (Erianthus and HSP70 transgenic sugarcane) under moisture stress in an actin-mediated pathway. The possible biological significance of the formation of drought-associated interlocking marginal lobes (DaIMLs) in sugarcane plants upon drought stress is discussed. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Selective filling for patterning in microfluidic channels and integration of chromatography in "lab-on-a-chip" devices using sol-gel technology

NASA Astrophysics Data System (ADS)

Jindal, Rohit

The last decade has seen tremendous advancement in the development of miniaturized chemical analysis system also known as "lab-on-a-chip". It is believed that the true potential of these devices will be achieved by integrating various functions such as separation, reaction, sensing, mixing, pumping, injection and detection onto a single chip. The ability to pattern different functionalities is indispensable for the development of highly integrated devices. In this work, a simple method based on the concept of selective filling is described for patterning in the microfluidic channels. It is based on the difference in the free energy of filling between an open and a covered part of the channel. This method was used for the integration of chromatography in the microfluidic devices. A chromatographic column was realized by utilizing sol-gel as an immobilization matrix for entrapping reversed phase chromatographic particles. Localization of the stationary phase was achieved using the selective filling technique. Channels were fabricated in quartz using photolithography and wet etching. Electroosmotic flow was used for manipulating fluid movement in the channels. Cross channel design was used for making a pulse injection of the solutes in the separation channel. An optical fiber setup was developed for carrying out on-chip UV absorbance detection. Stationary phase was created under different sol-gel synthesis conditions. It was established that the sol-gel synthesis carried out under acidic conditions provides the optimum synthesis conditions for creating separation column. Chromatographic performance of the stationary phase material was demonstrated by separating peptides present in a mixture. The sol-gel immobilization method was extended for the integration of micropump in the chip. The micropump enables pumping of the fluid in field free channels. Preliminary results, demonstrating the potential of carbon nanotubes as a support material in the microfluidic channels, were obtained using CVD (chemical vapor deposition) grown tubes in the channel. Results obtained in this work demonstrate the potential of selective filling technique along with sol-gel technology as a useful tool for the fabrication of multifunctional "lab-on-a-chip" devices.

Interdigital athlete's foot: new concepts in pathogenesis.

PubMed

Leyden, J J; Kligman, A M

1977-06-01

In our view, interdigital athlete's foot usually begins with invasion of the horny layer by dermatophytes. Because of hot weather, sweating, exercise, or tight shoes, enough moisture accumulates to stimulate an overgrowth of bacteria. Large numbers of normally resident aerobic diphtheroids cause the common wet, macerated type of athlete's foot, while an overgrowth of Gram-negative organisms, such as Pseudomonas and Proteus, is responsible for the more serious cases. The dry, scaly type (dermatophytosis simplex) often alternates with the wet, macerated type (dermatophytosis complex). Flare-ups are common in summer and can be experimentally induced by occlusion of fungus-infected feet. Suppression of bacteria is essential in treating symptomatic athlete's foot. This can be accomplished by exposing the feet to air (eg, wearing sandals) to enhance evaporation of water and prevent the accumulation of excess moisture that stimulates bacterial overgrowth. Topical antibiotics are another approach, with the ideal perhaps being an agent with both broad-spectrum antibacterial and antifungal activity. The newer imidazoles are broad-spectrum compounds but have limited activity against Gram-negative organisms. Our agent of choice, aluminum chloride, combines broad-spectrum antimicrobial activity with chemical drying, a two-pronged attack. We view drying as the decisive element. We doubt that any local treatment can permanently eradicate athlete's foot. Potent antifungal agents can virtually exterminate interdigital dermatophytes, but the inevitable presence of infection in the nails or on the soles assures reinfection. In shoe-wearing populations living in temperate climates, interdigital athlete's foot is mainly a seasonal disease. The various therapies discussed provide a variety of approaches to prevent or ameliorate hot-weather exacerbations.

Measuring the level of agreement in hematologic and biochemical values between blood sampling sites in leatherback sea turtles (Dermochelys coriacea).

PubMed

Stewart, Kimberly; Mitchell, Mark A; Norton, Terry; Krecek, Rosina C

2012-12-01

Conservation programs to protect endangered sea turtles are being instituted worldwide. A common practice in these programs is to collect blood to evaluate the health of the turtles. Several different venipuncture sites are used to collect blood from sea turtles for hematologic and biochemistry tests, depending on the species. To date, it is unknown what affect venipuncture site may have on sample results. The purpose of this study was to measure the level of agreement between hematologic and biochemistry values collected from the dorsal cervical sinus and the interdigital vein of leatherback (Dermochelys coriacea) sea turtles. Paired heparinized blood samples were obtained from the dorsal cervical sinus and the interdigital vein of 12 adult female nesting leatherback sea turtles on Keys Beach, St. Kitts, West Indies. Even though the sample population was small, the data for each chemistry were normally distributed, except for creatine kinase (CK). There was no significant difference when comparing biochemistry or hematologic values by venipuncture site, except for CK (P = 0.02). The level of agreement between sampling sites was considered good for albumin, calcium, globulin, glucose, packed cell volume, phosphorus, potassium, sodium, total protein, total solids, uric acid, white blood cell count, and all of the individual white cell types, while the level of agreement for aspartate aminotransferase and CK were considered poor. This information, coupled with the fact that the interdigital vein affords a less-invasive procedure, demonstrates that the interdigital vein is an appropriate location to use when establishing a hematologic and biochemical profile for leatherback sea turtles.

Characterization of craniofacial sutures using the finite element method.

PubMed

Maloul, Asmaa; Fialkov, Jeffrey; Wagner, Diane; Whyne, Cari M

2014-01-03

Characterizing the biomechanical behavior of sutures in the human craniofacial skeleton (CFS) is essential to understand the global impact of these articulations on load transmission, but is challenging due to the complexity of their interdigitated morphology, the multidirectional loading they are exposed to and the lack of well-defined suture material properties. This study aimed to quantify the impact of morphological features, direction of loading and suture material properties on the mechanical behavior of sutures and surrounding bone in the CFS. Thirty-six idealized finite element (FE) models were developed. One additional specimen-specific FE model was developed based on the morphology obtained from a µCT scan to represent the morphological complexity inherent in CFS sutures. Outcome variables of strain energy (SE) and von Mises stress (σvm) were evaluated to characterize the sutures' biomechanical behavior. Loading direction was found to impact the relationship between SE and interdigitation index and yielded varied patterns of σvm in both the suture and surrounding bone. Adding bone connectivity reduced suture strain energy and altered the σvm distribution. Incorporating transversely isotropic material properties was found to reduce SE, but had little impact on stress patterns. High-resolution µCT scanning of the suture revealed a complex morphology with areas of high and low interdigitations. The specimen specific suture model results were reflective of SE absorption and σvm distribution patterns consistent with the simplified FE results. Suture mechanical behavior is impacted by morphologic factors (interdigitation and connectivity), which may be optimized for regional loading within the CFS. © 2013 Elsevier Ltd. All rights reserved.

Low temperature synthesis of CaO-SiO2 glasses having stable liquid-liquid immiscibility by sol-gel process

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.

1990-01-01

Calcium silicate glass compositions lying within the liquid-liquid immiscibility dome of the phase diagram, which could not have been prepared by the conventional melting method, were synthesized by the sol-gel process. Hydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) solutions containing up to 20 mol percent calcium nitrate resulted in the formation of clear and transparent gels. The gel formation time decreased with increase in water:TEOS mole ratio, calcium content, and the reaction temperature. Smaller values of gel times in the presence of calcium nitrate are probably caused by lowering of the ionic charge on the sol particles by the salt present. The gelation activation energy, E(sub gel), was evaluated from temperature dependence of the gel time. Presence of Ca(2+) ions or the water:TEOS mole ratio did not have an appreciable effect on the value of E(sub gel). Presence of glycerol in the solution helped in the formation of crack-free monolithic gel specimens. Chemical and structural changes occurring in the gels, as a function of the heat treatments, have been monitored using DTA, TGA, IR-spectroscopy, x ray diffraction, surface area and pore size distribution measurements.

Low temperature synthesis of CaO-SiO2 glasses having stable liquid-liquid immiscibility by the sol-gel process

NASA Technical Reports Server (NTRS)

Bansal, N. P.

1992-01-01

Calcium silicate glass compositions lying within the liquid-liquid immiscibility dome of the phase diagram, which could not have been prepared by the conventional melting method, were synthesized by the sol-gel process. Hydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) solutions containing up to 20 mol percent calcium nitrate resulted in the formation of clear and transparent gels. The gel formation time decreased with increase in water: TEOS mole ratio, calcium content, and the reaction temperature. Smaller values of gel times in the presence of calcium nitrate are probably caused by lowering of the ionic charge on the sol particles by the salt present. The gelation activation energy, E(sub gel), was evaluated from temperature dependence of the gel time. Presence of Ca(2+) ions or the water:TEOS mole ratio did not have an appreciable effect on the value of E(sub gel). Presence of glycerol in the solution helped in the formation of crack-free monolithic gel specimens. Chemical and structural changes occurring in the gels, as a function of the heat treatments, have been monitored using DTA, TGA, IR-spectroscopy, X-ray diffraction, surface area and pore size distribution measurements.

Three-phase molecularly imprinted sol-gel based hollow fiber liquid-phase microextraction combined with liquid chromatography-tandem mass spectrometry for enrichment and selective determination of a tentative lung cancer biomarker.

PubMed

Moein, Mohammad Mahdi; Javanbakht, Mehran; Karimi, Mohammad; Akbari-Adergani, Behrouz; Abdel-Rehim, Mohamed

2015-07-15

In the present study, the modification of a polysulfone hollow fiber membrane with in situ molecularly imprinted sol-gel process (as a novel and one-step method) was prepared and investigated. 3-(propylmethacrylate)trimethoxysilane (3PMTMOS) as an inorganic precursor was used for preparation of molecularly imprinted sol-gel. The modified molecularly imprinted sol-gel hollow fiber membrane (MSHM) was used for the liquid-phase microextraction (LPME) of hippuric acid (HA) in human plasma and urine samples. MSHM as a selective, robust, and durable tool was used for at least 50 extractions without significant decrease in the extraction efficiency. The non-molecularly imprinted sol-gel hollow fiber membrane (NSHM) as blank hollow fiber membrane was prepared by the same process, only without HA. To achieve the best condition, influential parameters on the extraction efficiency were thoroughly investigated. The capability of this robust, green, and simple method for extraction of HA was successfully accomplished with LC/MS/MS. The limits of detection (LOD) and quantification (LOQ) in human plasma and urine samples were 0.3 and 1.0nmolL(-1), respectively. The standard calibration curves were obtained within the concentration range 1-2000nmolL(-1) for HA in human plasma and urine. The coefficients of determination (r(2)) were ≥0.998. The obtained data exhibited recoveries were higher than 89% for the extraction of HA in human plasma and urine samples. Copyright © 2015 Elsevier B.V. All rights reserved.

A theoretical evaluation of aluminum gel propellant two-phase flow losses on vehicle performance

NASA Technical Reports Server (NTRS)

Mueller, Donn C.; Turns, Stephen R.

1993-01-01

A one-dimensional model of a hydrocarbon/Al/O2(gaseous) fueled rocket combustion chamber was developed to study secondary atomization effects on propellant combustion. This chamber model was coupled with a two dimensional, two-phase flow nozzle code to estimate the two-phase flow losses associated with solid combustion products. Results indicate that moderate secondary atomization significantly reduces propellant burnout distance and Al2O3 particle size; however, secondary atomization provides only moderate decreases in two-phase flow induced I(sub sp) losses. Despite these two-phase flow losses, a simple mission study indicates that aluminum gel propellants may permit a greater maximum payload than the hydrocarbon/O2 bi-propellant combination for a vehicle of fixed propellant volume. Secondary atomization was also found to reduce radiation losses from the solid combustion products to the chamber walls, primarily through reductions in propellant burnout distance.

Fabrication and energy harvesting characteristics of unimorph piezoelectric cantilever generators with interdigitated electrode lead zirconate titanate laminates

NASA Astrophysics Data System (ADS)

Lee, Min-seon; Yun, Ji-sun; Park, Woon-ik; Hong, Youn-woo; Cho, Jeong-ho; Paik, Jong-hoo; Park, Yong Ho; Son, Chun-myung; Jeong, Young Hun

2017-12-01

Interdigitated electrode (IDE) unimorph piezoelectric cantilever generators (UPCGs) were fabricated and their energy harvesting characteristics were investigated. A hard lead zirconate titanate (PZT) material with a high mechanical quality factor (Q m) of 1280 was used for the active piezoelectric film of the IDE UPCGs. Two different laminated IDE UPCGs were prepared; one has Ag/Pd interdigitated electrode (IDE) formed only on the top and bottom PZT sheets (D-IDE), while the other has Ag/Pd IDE on all of the PZT sheets (M-IDE). Cofiring was conducted at 1050 °C for 2 h for PZT laminates with IDEs. The fabricated IDE UPCGs exhibited power densities of 50.4 µW/cm3 for the D-IDE and 820 µW/cm3 for the M-IDE. The UPCG with the M-IDE exhibited a higher performance than that with the D-IDE. Specifically, a significantly enhanced normalized power factor of 670 µW/(g2·cm3) was found at 118 Hz across 100 kΩ.

Electrogenerated Chemiluminescence of BODIPY, Ru(bpy)32+, and 9,10-Diphenylanthracene Using Interdigitated Array Electrodes

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

Nepomnyashchii, Alexander B.; Kolesov, Grigory; Parkinson, Bruce A.

Interdigitated array electrodes (IDAs) were used to produce steady-state electrogenerated chemiluminescence (ECL) by annihilation of oxidized and reduced forms of a substituted boron dipyrromethene (BODIPY) dye, 9,10-diphenylanthracene (DPA), and ruthenium(II) tris(bypiridine) (Ru-(bpy)32+). Digital simulations were in good agreement with the experimentally obtained currents and light outputs. Coreactant experiments, using tri-n-propylamine and benzoyl peroxide as a sacrificial homogeneous reductant or oxidant, show currents corresponding to electrode reactions of the dyes and not the oxidation or reduction of the coreactants. The results show that interdigitated arrays can produce stable ECL where the light intensity is magnified due to the larger currents asmore » a consequence of feedback between generator and collector electrodes in the IDA. The light output for ECL is around 100 times higher than that obtained with regular planar electrodes with similar area. This material is based upon work supported as part of the Center of Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences.« less

Dielectric capacitors with three-dimensional nanoscale interdigital electrodes for energy storage.

PubMed

Han, Fangming; Meng, Guowen; Zhou, Fei; Song, Li; Li, Xinhua; Hu, Xiaoye; Zhu, Xiaoguang; Wu, Bing; Wei, Bingqing

2015-10-01

Dielectric capacitors are promising candidates for high-performance energy storage systems due to their high power density and increasing energy density. However, the traditional approach strategies to enhance the performance of dielectric capacitors cannot simultaneously achieve large capacitance and high breakdown voltage. We demonstrate that such limitations can be overcome by using a completely new three-dimensional (3D) nanoarchitectural electrode design. First, we fabricate a unique nanoporous anodic aluminum oxide (AAO) membrane with two sets of interdigitated and isolated straight nanopores opening toward opposite planar surfaces. By depositing carbon nanotubes in both sets of pores inside the AAO membrane, the new dielectric capacitor with 3D nanoscale interdigital electrodes is simply realized. In our new capacitors, the large specific surface area of AAO can provide large capacitance, whereas uniform pore walls and hemispheric barrier layers can enhance breakdown voltage. As a result, a high energy density of 2 Wh/kg, which is close to the value of a supercapacitor, can be achieved, showing promising potential in high-density electrical energy storage for various applications.

Dielectric capacitors with three-dimensional nanoscale interdigital electrodes for energy storage

PubMed Central

Han, Fangming; Meng, Guowen; Zhou, Fei; Song, Li; Li, Xinhua; Hu, Xiaoye; Zhu, Xiaoguang; Wu, Bing; Wei, Bingqing

2015-01-01

Dielectric capacitors are promising candidates for high-performance energy storage systems due to their high power density and increasing energy density. However, the traditional approach strategies to enhance the performance of dielectric capacitors cannot simultaneously achieve large capacitance and high breakdown voltage. We demonstrate that such limitations can be overcome by using a completely new three-dimensional (3D) nanoarchitectural electrode design. First, we fabricate a unique nanoporous anodic aluminum oxide (AAO) membrane with two sets of interdigitated and isolated straight nanopores opening toward opposite planar surfaces. By depositing carbon nanotubes in both sets of pores inside the AAO membrane, the new dielectric capacitor with 3D nanoscale interdigital electrodes is simply realized. In our new capacitors, the large specific surface area of AAO can provide large capacitance, whereas uniform pore walls and hemispheric barrier layers can enhance breakdown voltage. As a result, a high energy density of 2 Wh/kg, which is close to the value of a supercapacitor, can be achieved, showing promising potential in high-density electrical energy storage for various applications. PMID:26601294

Broadband dielectric characterization of sapphire/TiOx/Ba₀.₃Sr₀.₇TiO₃ (111)-oriented thin films for the realization of a tunable interdigitated capacitor.

PubMed

Ghalem, Areski; Ponchel, Freddy; Remiens, Denis; Legier, Jean-Francois; Lasri, Tuami

2013-05-01

A complete microwave characterization up to 67 GHz using specific coplanar waveguides was performed to determine the dielectric properties (permittivity, losses, and tunability) of sapphire/TiOx/Ba0.3Sr0.7TiO3 (BST) (111)-oriented thin films. To that end, BaxSr1-xTiO3 thin films were deposited by RF magnetron sputtering on sapphire (0001) substrate. To control the preferred (111) orientation, a TiOx buffer layer was deposited on sapphire. According to the detailed knowledge of the material properties, it has been possible to conceive, fabricate, and test interdigitated capacitors, the basic element for future microwave tunable applications. Retention of capacitive behavior up to 67 GHz and a tunability of 32% at 67 GHz at an applied voltage of 30 V (150 kV/cm) were observed. The Q-factor remains greater than 30 over the entire frequency band. The possibility of a complete characterization of the material for the realization of high-performance interdigitated capacitors opens the door to microwave device fabrication.

Optimization of the coplanar interdigital capacitive sensor

NASA Astrophysics Data System (ADS)

Huang, Yunzhi; Zhan, Zheng; Bowler, Nicola

2017-02-01

Interdigital capacitive sensors are applied in nondestructive testing and material property characterization of low-conductivity materials. The sensor performance is typically described based on the penetration depth of the electric field into the sample material, the sensor signal strength and its sensitivity. These factors all depend on the geometry and material properties of the sensor and sample. In this paper, a detailed analysis is provided, through finite element simulations, of the ways in which the sensor's geometrical parameters affect its performance. The geometrical parameters include the number of digits forming the interdigital electrodes and the ratio of digit width to their separation. In addition, the influence of the presence or absence of a metal backplane on the sample is analyzed. Further, the effects of sensor substrate thickness and material on signal strength are studied. The results of the analysis show that it is necessary to take into account a trade-off between the desired sensitivity and penetration depth when designing the sensor. Parametric equations are presented to assist the sensor designer or nondestructive evaluation specialist in optimizing the design of a capacitive sensor.

Process for preparing silicon carbide foam

DOEpatents

Whinnery, LeRoy Louis; Nichols, Monte Carl; Wheeler, David Roger; Loy, Douglas Anson

1997-01-01

A method of preparing near net shape, monolithic, porous SiC foams is disclosed. Organosilicon precursors are used to produce polymeric gels by thermally induced phase separation, wherein, a sufficiently concentrated solution of an organosilicon polymer is cooled below its solidification temperature to form a gel. Following solvent removal from the gel, the polymer foam is pretreated in an oxygen plasma in order to raise its glass transition temperature. The pretreated foam is then pyrolized in an inert atmosphere to form a SiC foam.

Process for preparing silicon carbide foam

DOEpatents

Whinnery, L.L.; Nichols, M.C.; Wheeler, D.R.; Loy, D.A.

1997-09-16

A method of preparing near net shape, monolithic, porous SiC foams is disclosed. Organosilicon precursors are used to produce polymeric gels by thermally induced phase separation, wherein, a sufficiently concentrated solution of an organosilicon polymer is cooled below its solidification temperature to form a gel. Following solvent removal from the gel, the polymer foam is pretreated in an oxygen plasma in order to raise its glass transition temperature. The pretreated foam is then pyrolyzed in an inert atmosphere to form a SiC foam. 9 figs.

Ultra-low density microcellular polymer foam and method

DOEpatents

Simandl, Ronald F.; Brown, John D.

1996-01-01

An ultra-low density, microcellular open-celled polymer foam and a method for making such foam. A polymer is dissolved in a heated solution consisting essentially of at least one solvent for the dissolution of the polymer in the heated solution and the phase inversion of the dissolved polymer to a liquid gel upon sufficient cooling of the heated solution. The heated solution is contained in a containment means provided with a nucleating promoting means having a relatively rough surface formed of fixed nucleating sites. The heated solution is cooled for a period of time sufficient to form a liquid gel of the polymer by phase inversion. From the gel, a porous foam having a density of less than about 12.0 mg/cm.sup.3 and open porosity provided by well interconnected strut morphology is formed.

Ultra-low density microcellular polymer foam and method

DOEpatents

Simandl, R.F.; Brown, J.D.

1996-03-19

An ultra-low density, microcellular open-celled polymer foam and a method for making such foam are disclosed. A polymer is dissolved in a heated solution consisting essentially of at least one solvent for the dissolution of the polymer in the heated solution and the phase inversion of the dissolved polymer to a liquid gel upon sufficient cooling of the heated solution. The heated solution is contained in a containment means provided with a nucleating promoting means having a relatively rough surface formed of fixed nucleating sites. The heated solution is cooled for a period of time sufficient to form a liquid gel of the polymer by phase inversion. From the gel, a porous foam having a density of less than about 12.0 mg/cm{sup 3} and open porosity provided by well interconnected strut morphology is formed.

Solution-mediated growth of NBA-ZSM-5 crystals retarded by gel entrapment

NASA Astrophysics Data System (ADS)

Aguilar-Mamani, Wilson; Akhtar, Farid; Hedlund, Jonas; Mouzon, Johanne

2018-04-01

The synthesis of flat tablet-shaped ZSM-5 crystals from a gel using metakaolin as aluminosilicate source and n-butyl amine as structure directing agent was investigated. The evolution inside the solid phase was characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, thermogravimetry and mass spectrometry. A kinetic study indicated that the nucleation of the majority crystals occurred concurrently with the formation of the gel upon heating the starting liquid suspension. Microstructural evidences undeniably showed that the gel precipitated on ZSM-5 crystals and mineral impurities originating from kaolin. As a result, crystal growth was retarded by gel entrapment, as indicated by the configuration and morphology of the embedded crystals. The results presented herein are harmonized with a solution-mediated nucleation and growth mechanism. Our observations differ from the autocatalytic model that suggests that the nuclei rest inside the gel until released when the gel is consumed. Our results show instead that it is crystals that formed in an early stage before entrapment inside the gel that rest inside the gel until exposed at the gel surface. These results illustrate the limitation of the classical method used in the field to determine nucleation profiles when the crystals become trapped inside the gel.

Process for preparing energetic materials

DOEpatents

Simpson, Randall L [Livermore, CA; Lee, Ronald S [Livermore, CA; Tillotson, Thomas M [Tracy, CA; Hrubesh, Lawrence W [Pleasanton, CA; Swansiger, Rosalind W [Livermore, CA; Fox, Glenn A [Livermore, CA

2011-12-13

Sol-gel chemistry is used for the preparation of energetic materials (explosives, propellants and pyrotechnics) with improved homogeneity, and/or which can be cast to near-net shape, and/or made into precision molding powders. The sol-gel method is a synthetic chemical process where reactive monomers are mixed into a solution, polymerization occurs leading to a highly cross-linked three dimensional solid network resulting in a gel. The energetic materials can be incorporated during the formation of the solution or during the gel stage of the process. The composition, pore, and primary particle sizes, gel time, surface areas, and density may be tailored and controlled by the solution chemistry. The gel is then dried using supercritical extraction to produce a highly porous low density aerogel or by controlled slow evaporation to produce a xerogel. Applying stress during the extraction phase can result in high density materials. Thus, the sol-gel method can be used for precision detonator explosive manufacturing as well as producing precision explosives, propellants, and pyrotechnics, along with high power composite energetic materials.

PREPARATION AND PROPERTIES OF COMPOUND ARNEBIAE RADIX MICROEMULSION GEL

PubMed Central

Chen, Jing; He, Yanping; Gao, Ting; Zhang, Licheng; Zhao, Yuna

2017-01-01

Background: Compound Arnebiae radix oil has been clinically applied to treat burns and scalds for a long time. However, it is unstable and inconvenient to use. The aim of this study was to prepare a compound Arnebiae radix microemulsion gel for transdermal delivery system and evaluate its characteristics. Materials and Methods: Based on the solubility of Shikonin, the active component of Arnebiae radix and the results of phase studies, adequate ratio of each component in microemulsion was determined. The optimized microemulsion gel was prepared using Carbomer 940. The gels were characterized in terms of appearance, preliminary stability test and the content of Shikonin in the compound Arnebiae radix microemulsion gel with HPLC analysis. Results: The optimized conditions for preparing microemulsion were Tween-80, glycerin, isopropyl myristate (IPM) with the ratio of 6:3:2. The optimal microemulsion gel was obtained with Carbomer 940 (1.0%). Conclusion: The prepared compound Arnebiae radix microemulsion gel showed good stability over time. It is more convenience in application than the previous used formulations. PMID:28480438

PREPARATION AND PROPERTIES OF COMPOUND ARNEBIAE RADIX MICROEMULSION GEL.

PubMed

Chen, Jing; He, Yanping; Gao, Ting; Zhang, Licheng; Zhao, Yuna

2017-01-01

Compound Arnebiae radix oil has been clinically applied to treat burns and scalds for a long time. However, it is unstable and inconvenient to use. The aim of this study was to prepare a compound Arnebiae radix microemulsion gel for transdermal delivery system and evaluate its characteristics. Based on the solubility of Shikonin, the active component of Arnebiae radix and the results of phase studies, adequate ratio of each component in microemulsion was determined. The optimized microemulsion gel was prepared using Carbomer 940. The gels were characterized in terms of appearance, preliminary stability test and the content of Shikonin in the compound Arnebiae radix microemulsion gel with HPLC analysis. The optimized conditions for preparing microemulsion were Tween-80, glycerin, isopropyl myristate (IPM) with the ratio of 6:3:2. The optimal microemulsion gel was obtained with Carbomer 940 (1.0%). The prepared compound Arnebiae radix microemulsion gel showed good stability over time. It is more convenience in application than the previous used formulations.

Ferroelectric and piezoelectric properties of poly(vinylidene fluoride-trifluoroethylene) gels

NASA Astrophysics Data System (ADS)

Fukagawa, Miki; Koshiba, Yausko; Morimoto, Masahiro; Ishida, Kenji

2017-04-01

The structural, ferroelectric, and piezoelectric properties of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] gels fabricated using poly(pyridinium-1,4-diyliminocarbonyl-1,4-phenylenemethylene thiocyanate) (PICPM-SCN) as a gelator are investigated in this study. The P(VDF-TrFE)/PICPM-SCN composites formed thermally reversible physical gels and their analysis by Fourier transform infrared spectroscopy revealed that the P(VDF-TrFE) molecules in these gels exhibit predominantly the ferroelectric phase I (Form β). Furthermore, the polarization switching peaks of the P(VDF-TrFE)/PICPM-SCN gel films were clearly observed. The coercive electric field for these gel films was estimated to be 2 MV/m, which is dramatically lower than the values typically observed for P(VDF-TrFE) solid films (50 MV/m). Finally, the P(VDF-TrFE)/PICPM-SCN gel films exhibited a piezoelectric response, and the highest piezoelectric coefficient was determined to be ˜53 pm/V at an applied voltage frequency of 4 kHz.

Hybrid gels assembled from Fmoc-amino acid and graphene oxide with controllable properties.

PubMed

Xing, Pengyao; Chu, Xiaoxiao; Li, Shangyang; Ma, Mingfang; Hao, Aiyou

2014-08-04

A supramolecular gel is obtained from the self-assembly of an ultralow-molecular-weight gelator (N-fluorenyl-9-methoxycarbonyl glutamic acid) in good and poor solvents. The gelators can self-assemble into a lamellar structure, which can further form twisted fibers and nanotubes in the gel phase. Rheological studies show that the gels are robust and rigid, and are able to rapidly self-recover to a gel after being destroyed by shear force. Fluorescence experiments reveal the aggregation-induced emission effects of the gel system; the fluorescence intensity is significantly enhanced by gel formation. Graphene oxide (GO) is introduced into the system efficiently to give a hybrid material, and the interaction between gelators-GO sheets is studied. Rheological and fluorescent studies imply that the mechanical properties and the fluorescent emission of the hybrid materials can be fine-tuned by controlling the addition of GO. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Smart membranes: Hydroxypropyl cellulose for flavor delivery

NASA Astrophysics Data System (ADS)

Heitfeld, Kevin A.

2007-12-01

This work focuses on the use of temperature responsive gels (TRGs) (polymeric hydrogels with a large temperature-dependent change in volume) for flavor retention at cooking temperatures. Specifically, we have studied a gel with a lower critical solution temperature (LCST) that swells at low temperatures and collapses at high temperatures. In the collapsed state, the polymer acts as a transport barrier, keeping the volatile flavors inside. An encapsulation system was designed to utilize the solution (phase separation) behavior of a temperature responsive gel. The gel morphology was understood and diffusive properties were tailored through morphology manipulation. Heterogeneous and homogeneous gels were processed by understanding the effect of temperature on gel morphology. A morphology model was developed linking bulk diffusive properties to molecular morphology. Flavor was encapsulated within the gel and the emulsifying capability was determined. The capsules responded to temperature similarly to the pure polymer. The release kinetcs were compared to commercial gelatin capsules and the temperature responsive polymer took longer to release.

Graphene oxide based sol-gel stainless steel fiber for the headspace solid-phase microextraction of organophosphate ester flame retardants in water samples.

PubMed

Jin, Tingting; Cheng, Jing; Cai, Cuicui; Cheng, Min; Wu, Shiju; Zhou, Hongbin

2016-07-29

In this paper, graphene oxide was coated onto a stainless steel wire through sol-gel technique and it was used as a solid phase microextraction (SPME) fiber. The prepared fiber was characterized by scanning electron microscopy (SEM), which displayed that the fiber had crinkled surface and porous structure The application of the fiber was evaluated through the headspace SPME of nine organophosphate ester flame retardants (OPFRs) with different characteristics in water samples followed by gas chromatography and nitrogen-phosphorous detector (GC/NPD). The major factors influencing the extraction efficiency, including the extraction and desorption conditions, were studied and optimized. Under the optimum conditions, the proposed method was evaluated, and applied to the analysis of organophosphate ester flame retardants in real environmental water samples. The results demonstrated the HS-SPME method based on GO sol-gel fiber had good linearity (R>0.9928), and limits of detection (1.4-135.6ngL(-1)), high repeatability (RSD<9.8%) and good recovery (76.4-112.4%). The GO based sol-gel fiber displayed bigger extraction capability than the commercial PDMS fiber and the pure sol-gel fiber for both polar and apolar organophosphate esters, especially for the OPFRs containing benzene rings. Copyright © 2016 Elsevier B.V. All rights reserved.

Skin microbiome changes in patients with interdigital tinea pedis.

PubMed

Wang, R; Song, Y; Du, M; Yang, E; Yu, J; Wan, Z; Li, R

2018-04-28

Tinea pedis is a chronic, recurrent superficial fungal infection that most commonly involves the toe web spaces. 1 Previous culture-based studies have incompletely defined the microbial landscape associated with tinea pedis, which was considered the result of infection with a single fungus. However, the recalcitrant course of the disease suggests that microbial community shifts have a role in disease pathogenesis. 2 This study was conducted to characterize the bacterial and fungal microbiome changes associated with interdigital tinea pedis. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Evaluation of factor IX deficiency by interdigitated electrode (IDE)

NASA Astrophysics Data System (ADS)

Gopinath, Subash C. B.; Hashim, Uda; Uda, M. N. A.

2017-03-01

Factor IX deficiency is the main cause of hemophilia A and B. This a severe excessive bleeding disorder that can even kill the patient if not treated with the right prescription of Factor IX hormone to stop the bleeding. The bleeding can be caused by an injury or even a sudden bleeding in some very rare cases. To find the Factor IX effectiveness and to understand the deficiency more carefully for the future of medicine, experiments are conducted to test the Factor IX using the Interdigitated Electrode (IDE) and gold Nanoparticle with the help of Nanoelectrical technology.

Ultrasonication-assisted preparation and characterization of emulsions and emulsion gels for topical drug delivery.

PubMed

Singh, Vinay K; Behera, Baikuntha; Pramanik, Krishna; Pal, Kunal

2015-03-01

The current study describes the use of ultrasonication for the preparation of biphasic emulsions and emulsion gels for topical drug delivery. Sorbitan monostearate (SMS) was used as the surfactant for stabilizing the interface of sesame oil (apolar phase) and water (polar phase). Emulsions were formed at lower concentrations of SMS, whereas emulsion gels were formed at higher concentrations of SMS. The formulations were characterized by fluorescent microscopy, X-ray diffraction, viscosity, stress relaxation, spreadability, and differential scanning calorimetry studies. Fluorescence microscopy suggested formation of oil-in-water type of formulations. There was an increase in the viscosity, bulk resistance, and firmness of the formulations as the proportions of SMS was increased. The emulsion gels were viscoelastic in nature. Thermal studies suggested higher thermodynamic stability at higher proportions of either SMS or water. Metronidazole, a model antimicrobial drug, was incorporated within the formulations. The release of the drug from the formulations was found to be diffusion mediated. The drug-loaded formulations showed sufficient antimicrobial efficiency to be used as carriers for topical antimicrobial drug delivery. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

Polymeric ionic liquid bucky gels as sorbent coatings for solid-phase microextraction.

PubMed

Zhang, Cheng; Anderson, Jared L

2014-05-30

Novel cross-linked polymeric ionic liquid (PIL) bucky gels were formed by free-radical polymerization of polymerizable ionic liquids gelled with multi-walled carbon nanotubes (MWCNT) and used as sorbent coatings for solid-phase microextraction (SPME). The combination of PIL with MWCNTs significantly enhanced the π-π interaction between the sorbent coatings and the aromatic analytes. Compared to the neat PIL-based sorbent coating, the PIL bucky gel sorbent coatings demonstrated higher extraction efficiency for the extraction of polycyclic aromatic hydrocarbons (PAHs). A partitioning extraction mechanism was observed for the PIL/MWCNT-based sorbent coatings indicating that the addition of MWCNTs did not seem to affect the extraction mechanism of the sorbent coating. The analyte-to-coating partition coefficients (logKfs) were estimated and the limits of detection (LOD) for selected PIL bucky gel sorbent coating were determined to be in the range of 1-2.5 ng L(-1). Recovery studies were also performed for PAHs in river and tap water to validate the applicability of the developed method. Copyright © 2014 Elsevier B.V. All rights reserved.

A new separation and preconcentration method for selenium in some foods using modified silica gel with 2,6-diamino-4-phenil-1,3,5-triazine.

PubMed

Mendil, Durali; Demirci, Zafer; Uluozlu, Ozgur Dogan; Tuzen, Mustafa; Soylak, Mustafa

2017-04-15

A novel and simple solid phase extraction method was improved and recommended for selenium. Silica gel was modified with 2,6-diamino-4-phenil-1,3,5-triazine and characterized by FTIR, SEM and elemental analysis and used adsorbent for column solid phase extraction of selenium ions. The experimental parameters (pH, flow rates, amounts of the modified silica gel, concentration and type of eluent, volume of sample, etc.) on the recoveries of selenium were optimized. Standard reference materials were analyzed for validation of method. The present method was successfully applied to the detection of total selenium in water and microwave digested some food samples with quantitative recoveries (> 95%). The relative standard deviations were<8%. Matrix influences were not observed. The adsorption capacity of modified silica gel was 5.90mgg -1 . The LOD was 0.015μgL -1 . Enrichment factor was obtained as 50 for the introduced method. Copyright © 2016 Elsevier Ltd. All rights reserved.

Temperature-induced sol-gel transition and microgel formation in α-actinin cross-linked actin networks: A rheological study

NASA Astrophysics Data System (ADS)

Tempel, M.; Isenberg, G.; Sackmann, E.

1996-08-01

We have studied the sol-gel transition, the viscoelastic and the structural properties of networks constituted of semiflexible actin filaments cross-linked by α-actinin. Cross-linking was regulated in a reversible way by varying the temperature through the association-dissociation equilibrium of the actin-α-actinin system. Viscoelastic parameters [shear storage modulus G'(ω), phase shift tan(Φ)(ω), creep compliance J(t)] were measured as a function of temperature and actin-to-cross-linker ratio by a magnetically driven rotating disc rheometer. G'(ω) and tan(Φ)(ω) were studied at a frequency ω corresponding to the elastic plateau regime of the G'(ω) versus ω spectrum of the purely entangled solution. The microstructure of the networks was viewed by negative staining electron microscopy (EM). The phase shift tan(Φ) (or equivalently the viscosity η) diverges and reaches a maximum when approaching the apparent gel point from lower and higher temperatures, and the maximum defines the gel point (temperature Tg). The elastic plateau modulus G'N diverges at temperatures beyond this gel point TTg. The cross-linking transition (corresponding to a sol-gel transition at zero frequency) is interpreted in terms of a percolation model and the divergence of G'N at TTg), (2) that microscopic segregation takes place at T<=Tg leading to local formation of clusters (a state termed microgel), and (3) that at low actin-α-actinin ratios (rAα<=10) and low temperatures (T<=10 °C) macroscopic segregation into bundles of cross-linked actin filaments and a diluted solution of actin filaments is observed. The three regimes of network structure are represented by an equivalent phase diagram.

Effects of carotenoids on lipid bilayers.

PubMed

Johnson, Quentin R; Mostofian, Barmak; Fuente Gomez, Gabriel; Smith, Jeremy C; Cheng, Xiaolin

2018-01-31

Carotenoids have been found to be important in improving the integrity of biomembranes in eukaryotes. However, the molecular details of how carotenoids modulate the physical properties of biomembranes are unknown. To this end, we have conducted a series of molecular dynamics simulations of different biologically-relevant membranes in the presence of carotenoids. The carotenoid effect on the membrane was found to be specific to the identity of the carotenoid and the composition of the membrane itself. Therefore, different classes of carotenoids produce a different effect on the membrane, and different membrane phases are affected differently by carotenoids. It is apparent from our data that carotenoids do trigger the bilayer to become thinner. The mechanism by which this occurs depends on two competing factors, the ability of the lipid tails of opposing monolayers to either (1) compress or (2) interdigitate as the bilayer condenses. Indeed, carotenoids directly influence the physical properties via these two mechanisms, thus compacting the bilayer. However, the degree to which these competing mechanisms are utilized depends on the bilayer phase and the carotenoid identity.

Tuning colloidal quantum dot band edge positions through solution-phase surface chemistry modification

DOE PAGES

Kroupa, Daniel M.; Vörös, Márton; Brawand, Nicholas P.; ...

2017-05-16

Band edge positions of semiconductors determine their functionality in many optoelectronic applications such as photovoltaics, photoelectrochemical cells and light emitting diodes. Here we show that band edge positions of lead sulfide (PbS) colloidal semiconductor nanocrystals, specifically quantum dots (QDs), can be tuned over 2.0 eV through surface chemistry modification. We achieved this remarkable control through the development of simple, robust and scalable solution-phase ligand exchange methods, which completely replace native ligands with functionalized cinnamate ligands, allowing for well-defined, highly tunable chemical systems. By combining experiments and ab initio simulations, we establish clear relationships between QD surface chemistry and the bandmore » edge positions of ligand/QD hybrid systems. We find that in addition to ligand dipole, inter-QD ligand shell inter-digitization contributes to the band edge shifts. As a result, we expect that our established relationships and principles can help guide future optimization of functional organic/inorganic hybrid nanostructures for diverse optoelectronic applications.« less

Tuning colloidal quantum dot band edge positions through solution-phase surface chemistry modification

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

Kroupa, Daniel M.; Vörös, Márton; Brawand, Nicholas P.

Band edge positions of semiconductors determine their functionality in many optoelectronic applications such as photovoltaics, photoelectrochemical cells and light emitting diodes. Here we show that band edge positions of lead sulfide (PbS) colloidal semiconductor nanocrystals, specifically quantum dots (QDs), can be tuned over 2.0 eV through surface chemistry modification. We achieved this remarkable control through the development of simple, robust and scalable solution-phase ligand exchange methods, which completely replace native ligands with functionalized cinnamate ligands, allowing for well-defined, highly tunable chemical systems. By combining experiments and ab initio simulations, we establish clear relationships between QD surface chemistry and the bandmore » edge positions of ligand/QD hybrid systems. We find that in addition to ligand dipole, inter-QD ligand shell inter-digitization contributes to the band edge shifts. As a result, we expect that our established relationships and principles can help guide future optimization of functional organic/inorganic hybrid nanostructures for diverse optoelectronic applications.« less

Tuning colloidal quantum dot band edge positions through solution-phase surface chemistry modification

PubMed Central

Kroupa, Daniel M.; Vörös, Márton; Brawand, Nicholas P.; McNichols, Brett W.; Miller, Elisa M.; Gu, Jing; Nozik, Arthur J.; Sellinger, Alan; Galli, Giulia; Beard, Matthew C.

2017-01-01

Band edge positions of semiconductors determine their functionality in many optoelectronic applications such as photovoltaics, photoelectrochemical cells and light emitting diodes. Here we show that band edge positions of lead sulfide (PbS) colloidal semiconductor nanocrystals, specifically quantum dots (QDs), can be tuned over 2.0 eV through surface chemistry modification. We achieved this remarkable control through the development of simple, robust and scalable solution-phase ligand exchange methods, which completely replace native ligands with functionalized cinnamate ligands, allowing for well-defined, highly tunable chemical systems. By combining experiments and ab initio simulations, we establish clear relationships between QD surface chemistry and the band edge positions of ligand/QD hybrid systems. We find that in addition to ligand dipole, inter-QD ligand shell inter-digitization contributes to the band edge shifts. We expect that our established relationships and principles can help guide future optimization of functional organic/inorganic hybrid nanostructures for diverse optoelectronic applications. PMID:28508866

Tuning colloidal quantum dot band edge positions through solution-phase surface chemistry modification

NASA Astrophysics Data System (ADS)

Kroupa, Daniel M.; Vörös, Márton; Brawand, Nicholas P.; McNichols, Brett W.; Miller, Elisa M.; Gu, Jing; Nozik, Arthur J.; Sellinger, Alan; Galli, Giulia; Beard, Matthew C.

2017-05-01

Band edge positions of semiconductors determine their functionality in many optoelectronic applications such as photovoltaics, photoelectrochemical cells and light emitting diodes. Here we show that band edge positions of lead sulfide (PbS) colloidal semiconductor nanocrystals, specifically quantum dots (QDs), can be tuned over 2.0 eV through surface chemistry modification. We achieved this remarkable control through the development of simple, robust and scalable solution-phase ligand exchange methods, which completely replace native ligands with functionalized cinnamate ligands, allowing for well-defined, highly tunable chemical systems. By combining experiments and ab initio simulations, we establish clear relationships between QD surface chemistry and the band edge positions of ligand/QD hybrid systems. We find that in addition to ligand dipole, inter-QD ligand shell inter-digitization contributes to the band edge shifts. We expect that our established relationships and principles can help guide future optimization of functional organic/inorganic hybrid nanostructures for diverse optoelectronic applications.

Functional nucleic acid entrapment in sol-gel derived materials.

PubMed

Carrasquilla, Carmen; Brennan, John D

2013-10-01

Functional nucleic acids (FNAs) are single-stranded DNA or RNA molecules, typically generated through in vitro selection, that have the ability to act as receptors for target molecules (aptamers) or perform catalysis of a chemical reaction (deoxyribozymes and ribozymes). Fluorescence-signaling aptamers and deoxyribozymes have recently emerged as promising biological recognition and signaling elements, although little has been done to evaluate their potential for solid-phase assays, particularly with species made of RNA due to their lack of chemical stability and susceptibility to nuclease attack. Herein, we present a detailed overview of the methods utilized for solid-phase immobilization of FNAs using a sol-gel entrapment method that can provide protection from nuclease degradation and impart long-term chemical stability to the FNA reporter systems, while maintaining their signaling capabilities. This article will also provide a brief review of the results of such entrapment studies involving fluorescence-signaling versions of a DNA aptamer, selected RNA-cleaving deoxyribozymes, and two different RNA aptamers in a series of sol-gel derived composites, ranging from highly polar silica to hydrophobic methylsilsesquioxane-based materials. Given the ability to produce sol-gel derived materials in a variety of configurations, particularly as thin film coatings on electrodes, optical fibers, and other devices, this entrapment method should provide a useful platform for numerous solid-phase FNA-based biosensing applications. Copyright © 2013 Elsevier Inc. All rights reserved.

Nanoscale Charge-Balancing Mechanism in Alkali-Substituted Calcium-Silicate-Hydrate Gels.

PubMed

Özçelik, V Ongun; White, Claire E

2016-12-15

Alkali-activated materials and related alternative cementitious systems are sustainable technologies that have the potential to substantially lower the CO 2 emissions associated with the construction industry. However, these systems have augmented chemical compositions as compared to ordinary Portland cement (OPC), which may impact the evolution of the hydrate phases. In particular, calcium-silicate-hydrate (C-S-H) gel, the main hydrate phase in OPC, is likely to be altered at the atomic scale due to changes in the bulk chemical composition, specifically via the addition of alkalis (i.e., Na or K) and aluminum. Here, via density functional theory calculations, we reveal the presence of a charge balancing mechanism at the molecular level in C-S-H gel (as modeled using crystalline 14 Å tobermorite) when alkalis and aluminum atoms are introduced into the structure. Different structural representations are obtained depending on the level of substitution and the degree of charge balancing incorporated in the structures. The impact of these substitutional and charge balancing effects on the structures is assessed by analyzing the formation energies, local bonding environments, diffusion barriers and mechanical properties. The results of this computational study provide information on the phase stability of alkali/aluminum containing C-S-H gels, shedding light on the fundamental atomic level mechanisms that play a crucial role in these complex disordered materials.

In Situ Observations of Thermoreversible Gelation and Phase Separation of Agarose and Methylcellulose Solutions under High Pressure.

PubMed

Kometani, Noritsugu; Tanabe, Masahiro; Su, Lei; Yang, Kun; Nishinari, Katsuyoshi

2015-06-04

Thermoreversible sol-gel transitions of agarose and methylcellulose (MC) aqueous solutions on isobaric cooling or heating under high pressure up to 400 MPa have been investigated by in situ observations of optical transmittance and falling-ball experiments. For agarose, which undergoes the gelation on cooling, the application of pressure caused a gradual rise in the cloud-point temperature over the whole pressure range examined, which is almost consistent with the pressure dependence of gelling temperature estimated by falling-ball experiments, suggesting that agarose gel is stabilized by compression and that the gelation occurs nearly in parallel with phase separation under ambient and high-pressure conditions. For MC, which undergoes the gelation on heating, the cloud-point temperature showed a slight rise with an initial elevation of pressure up to ∼150 MPa, whereas it showed a marked depression above 200 MPa. In contrast, the gelling temperature of MC, which is nearly identical to the cloud-point temperature at ambient pressure, showed a monotonous rise with increasing pressure up to 350 MPa, which means that MC undergoes phase separation prior to gelation on heating under high pressure above 200 MPa. Similar results were obtained for the melting process of MC gel on cooling. The unique behavior of the sol-gel transition of MC under high pressure has been interpreted in terms of the destruction of hydrophobic hydration by compression.

Phase and microstructural development in alumina sol-gel coatings on CoCr alloy.

PubMed

Bae, I J; Standard, O C; Roger, G J; Brazil, D

2004-09-01

Phase transformation of gamma-Al(2)O(3) to alpha-Al(2)O(3) in alumina sol gel coatings on biomedical CoCr alloy was studied as function of heat treatment temperature and time. Transformation in unseeded coatings was significant only above approximately 1200 degrees C. Addition of alpha-Al(2)O(3) seed particles having an average size of approximately 40 nm lowered the phase transformation temperature to around 800 degrees C. These particles were considered to act as heterogeneous nucleation sites for epitaxial growth of the alpha-Al(2)O(3) phase. The kinetics and activation energy (420 kJ/mol) for the phase transformation in the seeded coatings were similar to those reported for seeded monolithic alumina gels indicating that the transformation mechanism is the same in the two material configurations. Avrami growth parameters indicated that the mechanism was diffusion controlled and invariant over the temperature range studied but that growth was possibly constrained by the finite size of the seed particles and/or coating thickness. The phase transformation occurred by the growth of alpha-Al(2)O(3) grains at the expense of the precursor fine-grained gamma-Al(2)O(3) matrix and near-complete transformation coincided with physical impingement of the growing grains. The grain size at impingement was approximately 100 nm which agreed well with that predicted from the theoretical linear spacing of seed particles in the initial sol.

In situ growth of sol-gel-derived nano-VO2 film and its phase transition characteristics

NASA Astrophysics Data System (ADS)

Shi, Qiwu; Huang, Wanxia; Lu, Tiecheng; Yue, Fang; Xiao, Yang; Hu, Yanyan

2014-10-01

We reported the growth of VO2 film deposited by an inorganic sol-gel method, followed by post-annealing. An in situ evolution of the grain size in the films with different annealing temperatures (300, 500, and 700 °C for 90 min), annealing times (500 °C for 20, 40, 60, and 90 min), and film thicknesses (30, 150 and 320 nm) was observed. The results indicated that the grain size distribution in the sol-gel-derived VO2 films was mediated by the density of nucleation center, which was varied in the films with different extents of thermal deformation during the annealing. By increasing the film thickness from 30 to 320 nm, a compact nanostructure with uniform distribution of grain size could be formed. It suggested that the in situ-evolved nanostructure in the thicker VO2 film will lead to lower threshold temperature and enhanced transition intensity in the phase transition. The effect of nanoscale grain size on the lower phase transition temperature in the VO2 film was discussed.

Untangle soil-water-mucilage interactions: 1H NMR Relaxometry is lifting the veil

NASA Astrophysics Data System (ADS)

Brax, Mathilde; Buchmann, Christian; Schaumann, Gabriele Ellen

2017-04-01

Mucilage is mainly produced at the root tips and has a high water holding capacity derived from highly hydrophilic gel-forming substances. The objective of the MUCILAGE project is to understand the mechanistic role of mucilage for the regulation of water supply for plants. Our subproject investigates the chemical and physical properties of mucilage as pure gel and mixed with soil. 1H-NMR Relaxometry and PFG NMR represent non-intrusive powerful methods for soil scientific research by allowing quantification of the water distribution as well as monitoring of the water mobility in soil pores and gel phases.Relaxation of gel water differs from the one of pure water due to additional interactions with the gel matrix. Mucilage in soil leads to a hierarchical pore structure, consisting of the polymeric biohydrogel network surrounded by the surface of soil particles. The two types of relaxation rates 1/T1 and 1/T2 measured with 1H-NMR relaxometry refer to different relaxation mechanisms of water, while PFG-NMR measures the water self-diffusion coefficient. The objective of our study is to distinguish in situ water in gel from pore water in a simplified soil system, and to determine how the "gel effect" affects both relaxation rates and the water self-diffusion coefficient in porous systems. We demonstrate how the mucilage concentration and the soil solution alter the properties of water in the respective gel phases and pore systems in model soils. To distinguish gel-inherent processes from classical processes, we investigated the variations of the water mobility in pure chia mucilage under different conditions by using 1H-NMR relaxometry and PFG NMR. Using model soils, the signals coming from pore water and gel water were differentiated. We combined the equations describing 1H-NMR relaxation in porous systems and our experimental results, to explain how the presence of gel in soil affects 1H-NMR relaxation. Out of this knowledge we propose a method, which determines in situ the presence of mucilage in soil and characterizes several gel-specific parameters of the mucilage. Based on these findings, we discussed the potential and limitations of 1H-NMR relaxometry for following natural swelling and shrinking processes of a natural biopolymer in soil.

Safety and Effectiveness of BufferGel and 0.5% PRO2000 Gel for the Prevention of HIV Infection in Women

PubMed Central

Karim, Salim S Abdool; Richardson, Barbra A; Ramjee, Gita; Hoffman, Irving F; Chirenje, Zvavahera M; Taha, Taha; Kapina, Muzala; Maslankowski, Lisa; Coletti, Anne; Profy, Albert; Moench, Thomas R.; Piwowar-Manning, Estelle; Mâsse, Benoît; Hillier, Sharon L.; Soto-Torres, Lydia

2011-01-01

Objective To determine the safety and effectiveness of BufferGel and 0.5% PRO2000 microbicide gels for the prevention of male to female HIV transmission Design Phase II/IIb, randomized, placebo-controlled trial with three double-blinded gel arms and an open label no gel arm. Methods Study participants from Malawi, South Africa, Zambia, Zimbabwe and USA were instructed to apply study gel ≤1 hour before each sex act and safety, sexual behavior, pregnancy, gel adherence, acceptability, and HIV serostatus were assessed during follow-up. Results The 3101 enrolled women were followed for an average of 20.4 months with 93.6% retention and 81.1% self-reported gel adherence. Adverse event rates were similar in all study arms. HIV incidence rates in the 0.5% PRO2000 Gel, BufferGel, Placebo Gel and No Gel arms were 2.70, 4.14, 3.91 and 4.02 per 100 women-years, respectively. HIV incidence in the 0.5% PRO2000 Gel arm was lower than the Placebo Gel arm (Hazard Ratio (HR)=0.7; p=0.10) and the No Gel arm (HR=0.67; p=0.06). HIV incidence rates were similar in the BufferGel and both Placebo Gel (HR=1.10; p=0.63) and No Gel control arms (HR=1.05; p=0.78). HIV incidence was similar in the Placebo Gel and No Gel arms (HR=0.97; p=0.89). Conclusions 0.5% PRO2000 Gel demonstrated a modest 30% reduction in HIV acquisition in women. However, these results were not statistically significant and subsequent findings from the MDP 301 trial have confirmed that 0.5% PRO2000 has little or no protective effect. BufferGel did not alter the risk of HIV infection. Both products were safe. PMID:21330907

Water Holding as Determinant for the Elastically Stored Energy in Protein-Based Gels.

PubMed

Pouvreau, Laurice; van Wijlen, Emke; Klok, Jan; Urbonaite, Vaida; Munialo, Claire D; de Jongh, Harmen H J

2016-04-01

To evaluate the importance of the water holding capacity for the elastically stored energy of protein gels, a range of gels were created from proteins from different origin (plant: pea and soy proteins, and animal: whey, blood plasma, egg white proteins, and ovalbumin) varying in network morphology set by the protein concentration, pH, ionic strength, or the presence of specific ions. The results showed that the observed positive and linear relation between water holding (WH) and elastically stored energy (RE) is generic for globular protein gels studied. The slopes of this relation are comparable for all globular protein gels (except for soy protein gels) whereas the intercept is close to 0 for most of the systems except for ovalbumin and egg white gels. The slope and intercept obtained allows one to predict the impact of tuning WH, by gel morphology or network stiffness, on the mechanical deformation of the protein-based gel. Addition of charged polysaccharides to a protein system leads to a deviation from the linear relation between WH and RE and this deviation coincides with a change in phase behavior. © 2016 Institute of Food Technologists®

Ionic liquids gels: Soft materials for environmental remediation.

PubMed

Marullo, Salvatore; Rizzo, Carla; Dintcheva, Nadka T; Giannici, Francesco; D'Anna, Francesca

2018-05-01

Nanostructured sorbents and, in particular, supramolecular gels are emerging as efficient materials for the removal of toxic contaminants from water, like industrial dyes. It is also known that ionic liquids can dissolve significant amounts of dyes. Consequently, supramolecular ionic liquids gels could be highly efficient sorbents for dyes removal. This would also contribute to overcome the drawbacks associated with dye removal by liquid-liquid extraction with neat ionic liquids which would require large volumes of extractant and a more difficult separation of the phases. Herein we employed novel supramolecular ionic liquid gels based on diimidazolium salts bearing naturally occurring or biomass derived anions, to adsorb cationic and anionic dyes from wastewaters. We also carried out a detailed investigation of thermal, structural, morphological and rheological features of our gels to identify which of them are key in designing better sorbents for environmental remediation. The most effective gels showed fast and thorough removal of cationic dyes like Rhodamine B. These gels could also be reused up to 20 times without any loss in removal efficiency. Overall, our ionic gels outperform most of gel-based sorbents systems so far reported in literature. Copyright © 2018 Elsevier Inc. All rights reserved.

Preparation of a collagen/polymer hybrid gel designed for tissue membranes. Part I: controlling the polymer-collagen cross-linking process using an ethanol/water co-solvent.

PubMed

Nam, Kwangwoo; Kimura, Tsuyoshi; Funamoto, Seiichi; Kishida, Akio

2010-02-01

The drawback with collagen/2-methacryloyloxyethyl phosphorylcholine (MPC) polymer hybrid gels (collagen/phospholipid polymer hybrid gels) prepared in alkaline morpholinoethane sulfonic acid (MES) aqueous solution is that the cross-linking rate between the polymer and the collagen is low. To solve this problem, ethanol has been adopted as the reaction solvent, to prevent 1-ethyl-3-(3-dimethylaminopropyl)-1-carbodiimide hydrochloride (EDC) hydrolysis. Alterations in the ethanol mole concentration changed the cross-linking rate between the MPC polymer and the collagen gel. Prevention of EDC hydrolysis is clearly observed; protonation of carboxyl groups implies that the ratio of ethanol to water should be controlled. The polymer shows signs of penetration into the collagen gel layer, thus forming a totally homogeneous phase gel. This affects the mechanical strength of the collagen gel, making the gel much stiffer and brittle with an increase in the swelling ratio, as compared with that prepared in MES buffer. However, it is possible to obtain a collagen/phospholipid polymer hybrid gel with a high polymer portion and the cross-linking rate can be successfully controlled.

A randomized, blinded, multicenter trial of a gentamicin vancomycin gel (DFA-02) in patients undergoing abdominal surgery.

PubMed

Bennett-Guerrero, Elliott; Berry, Scott M; Bergese, Sergio D; Fleshner, Phillip R; Minkowitz, Harold S; Segura-Vasi, Alvaro M; Itani, Kamal M F; Henderson, Karen W; Rackowski, Felicia P; Aberle, Laura H; Stryjewski, Martin E; Corey, G Ralph; Allenby, Kent S

2017-06-01

SI is a significant medical problem. DFA-02 is an investigational bioresorbable modified release gel consisting of both gentamicin (16.8 mg/mL) and vancomycin (18.8 mg/mL). A Phase 2a study, where the drug was applied during surgical incision closure, suggested safety and tolerability but was not designed to assess its efficacy. In a Phase 2b randomized, blinded trial patients undergoing abdominal, primarily colorectal, surgery were randomized (4:1:1) to one of three study arms: DFA-02, matching placebo gel, or standard of care (SOC) involving irrigation of the wound with normal saline. The DFA-02 and placebo gel groups received up to 20 mL of study drug inserted above the fascia during wound closure, and were treated in a double-blind manner; the SOC group was treated in a single-blind manner. The primary endpoint was SSI (adjudicated centrally by a blinded committee) through postoperative day 30. Overall, 445 subjects (intention-to-treat) were randomized at 35 centers with 425 subjects completing the study and being evaluable. There were 67 SSIs (15.8%): 64.2% superficial, 7.5% deep, and 28.4% organ space. The incidence of SSI was not statistically significantly different between the DFA-02 and the placebo gel/SOC arms combined, 42/287 = 14.6% vs 25/138 = 18.1% (p = 0.36), respectively. Rehospitalization within 30 days was also similar between study groups (DFA-02 28.6%, placebo gel 21.4%, SOC 27.3%). In this multicenter, blinded, randomized trial with central adjudication, the gentamicin/vancomycin gel was not associated with a significant reduction in SSI. Patients undergoing abdominal surgery were randomized to one of three study arms: DFA-02 gel consisting of both gentamicin and vancomycin, matching placebo gel, or standard of care (SOC). Of 425 patients completing the study at 35 sites the gentamicin/vancomycin gel was not associated with a significant reduction in SSI. Copyright © 2016 Elsevier Inc. All rights reserved.

Formation of porous crystals via viscoelastic phase separation

NASA Astrophysics Data System (ADS)

Tsurusawa, Hideyo; Russo, John; Leocmach, Mathieu; Tanaka, Hajime

2017-10-01

Viscoelastic phase separation of colloidal suspensions can be interrupted to form gels either by glass transition or by crystallization. With a new confocal microscopy protocol, we follow the entire kinetics of phase separation, from homogeneous phase to different arrested states. For the first time in experiments, our results unveil a novel crystallization pathway to sponge-like porous crystal structures. In the early stages, we show that nucleation requires a structural reorganization of the liquid phase, called stress-driven ageing. Once nucleation starts, we observe that crystallization follows three different routes: direct crystallization of the liquid phase, the Bergeron process, and Ostwald ripening. Nucleation starts inside the reorganized network, but crystals grow past it by direct condensation of the gas phase on their surface, driving liquid evaporation, and producing a network structure different from the original phase separation pattern. We argue that similar crystal-gel states can be formed in monatomic and molecular systems if the liquid phase is slow enough to induce viscoelastic phase separation, but fast enough to prevent immediate vitrification. This provides a novel pathway to form nanoporous crystals of metals and semiconductors without dealloying, which may be important for catalytic, optical, sensing, and filtration applications.

Substitution effect in reversible gel-liquid phase transformation polyoxometalate ionic liquid compounds.

PubMed

Wu, Xuefei; Cai, Huaxue; Wu, Qingyin; Yan, Wenfu

2016-07-28

The substitution effect in a series of POM-type reversible gel-liquid phase transformation ionic liquid compounds, [MIMPS]8P2W16V2O62, [MIMPS]6H2P2W16V2O62 and [MIMPS]4H4P2W16V2O62, has been investigated. Interestingly, there is an obvious substitution effect on the physicochemical properties of these compounds. When protons are substituted in place of ammonium, both the conductivity and the thermo-stability of the compounds can be increased a lot, and more protons can enhance this tendency.

Tailoring the Microstructure of Sol–Gel Derived Hydroxyapatite/Zirconia Nanocrystalline Composites

PubMed Central

2011-01-01

In this study, we tailor the microstructure of hydroxyapatite/zirconia nanocrystalline composites by optimizing processing parameters, namely, introducing an atmosphere of water vapor during sintering in order to control the thermal stability of hydroxyapatite, and a modified sol–gel process that yields to an excellent intergranular distribution of zirconia phase dispersed intergranularly within the hydroxyapatite matrix. In terms of mechanical behavior, SEM images of fissure deflection and the presence of monoclinic ZrO2 content on cracked surface indicate that both toughening mechanisms, stress-induced tetragonal to monoclinic phase transformation and deflection, are active for toughness enhancement. PMID:24764458

[Fungal aetiologies and contributing factors of interdigital tinea pedis among policemen in Abidjan (Ivory Coast)].

PubMed

Kiki-Barro, P C M; Konaté, A; Angora, E K; Kassi, F K; Bosson-Vanga, H; Bedia-Tanoh, A V; Djohan, V; Yavo, W; Menan, E I H

2017-12-01

Fungal interdigital tinea pedis are poorly documented in Ivory Coast. This study aimed to determine the distribution of fungal species and contributing factors of the disease among policemen in Abidjan. Our cross-sectional study was carried out at the police school in Abidjan. Our patients consisted of symptomatic or non-symptomatic police students. Samples of scales or serosities taken from inter-toes spaces were examinated with KOH mount and cultured on Sabouraud-chloramphenicol and Sabouraud-chloramphenicol-actidione media. The method of identification depended on the observed fungus. Among the 303 police students with clinical lesions of the inter-toe folds, 233 (76.9%; IC 95%=71.9-81.4) had a positive diagnosis after mycological examination. Lesions were predominantly located in the 3rd and 4th interdigital plantar spaces, with desquamation (100%) followed by maceration (82.5%) as the predominant functional sign. Dermatophytes accounted for 86.3% of the strains isolated with as majority species : Trichophyton interdigitale (40.3%), Microsporum langeronii (30.0%) and Trichophyton rubrum (15.5%). Yeasts accounted for 13.7% of the strains with Candida albicans (7.7%) as the most found species. The duration at the police school (P=0.004) and the practice of sports activities (P=0.0001) were statistically associated with the occurrence of the disease. A good hygiene of feet would reduce the incidence of the disease among the defense and security forces. Also, investigations for the influence of the seasons in the occurrence of interdigital tinea pedis will allow a better understand of epidemiology of this dermatomycosis. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Neoadjuvant Interdigitated Chemoradiotherapy Using Mesna, Doxorubicin, and Ifosfamide for Large, High-grade, Soft Tissue Sarcomas of the Extremity: Improved Efficacy and Reduced Toxicity.

PubMed

Chowdhary, Mudit; Sen, Neilayan; Jeans, Elizabeth B; Miller, Luke; Batus, Marta; Gitelis, Steven; Wang, Dian; Abrams, Ross A

2018-05-18

Patients with large, high-grade extremity soft tissue sarcoma (STS) are at high risk for both local and distant recurrence. RTOG 95-14, using a regimen of neoadjuvant interdigitated chemoradiotherapy with mesna, doxorubicin, ifosfamide, and dacarbazine followed by surgery and 3 cycles of adjuvant mesna, doxorubicin, ifosfamide, and dacarbazine, demonstrated high rates of disease control at the cost of significant toxicity (83% grade 4, 5% grade 5). As such, this regimen has not been widely adopted. Herein, we report our institutional outcomes utilizing a modified interdigitated chemoradiotherapy regimen, without dacarbazine, and current radiotherapy planning and delivery techniques for high-risk STS. Adults with large (≥5 cm; median, 12.9 cm), grade 3 extremity STS who were prospectively treated as part of our institutional standard of care from 2008 to 2016 are included. Neoadjuvant chemoradiotherapy consisted of 3 cycles of mesna, doxorubicin, and ifosfamide (MAI) and 44 Gy (22 Gy in 11 fractions between cycles of MAI) after which patients underwent surgical resection and received 3 additional cycles of MAI. Twenty-six patients received the MAI treatment protocol. At a median follow-up of 47.3 months, 23 (88.5%) patients are still alive. Three year locoregional recurrence-free survival, disease-free survival, and overall survival are 95.0%, 64.0%, and 95.0%, respectively. There have been no therapy-related deaths or secondary malignancies. The nonhematologic grade 4 toxicity rate was 7.7%. Neoadjuvant interdigitated MAI radiotherapy followed by resection and 3 cycles of adjuvant MAI has resulted in acceptable and manageable toxicity and highly favorable survival in patients at greatest risk for treatment failure.

Cranial suture complexity in caviomorph rodents (Rodentia; Ctenohystrica).

PubMed

Buezas, Guido; Becerra, Federico; Vassallo, Aldo

2017-08-01

Due to their flexibility, sutures are regions that experience greater strains than the surrounding rigid cranial bones. Cranial sutures differ in their degree of interdigitation or complexity. There is evidence indicating that a more convoluted suture better enables the absorption of high stresses coming from dynamic masticatory forces, and other functions. The Order Rodentia is an interesting clade to study this because of its taxa with diverse chewing modes. Due to repeated loading resulting from gnawing and grinding, energy absorption by the sutures might be a crucial factor in these mammals. Species within the infraorder Caviomorpha were chosen as a case study because of their ecomorphological and dietary diversity. This study compared five sutures from the rostrum and cranial vault across seven caviomorph families, and assessed their complexity by means of the relative length and fractal dimension. Across these rodents, cranial sutures are morphologically quite diverse. We found that the sutures connecting the rostrum with the vault were relatively more interdigitated than those in the cranial vault itself, especially premaxillofrontal sutures. Suture interdigitation was higher in species that display chisel-tooth digging and burrowing behaviors, especially in the families Ctenomyidae and Octodontidae, than those in families Dasyproctidae and Cuniculidae, which have more gracile masticatory systems. The reconstruction of the ancestral character state, on family and species phylogeny, points toward low suture interdigitation (i.e., low length ratio) as a likely ancestral state for interfrontal, premaxillofrontal and maxillofrontal sutures. Interspecific differences in suture morphology shown here might represent adaptations to different mechanical demands (i.e., soft vs. tough foods) or behaviors (e.g., chisel-tooth digging), which evolved in close association with the diverse environments occupied by caviomorph rodents. © 2017 Wiley Periodicals, Inc.

Lateral organization of mixed, two-phosphatidylcholine liposomes as investigated by GPS, the slope of Laurdan generalized polarization spectra.

PubMed

Vallejo, Alba A; Velázquez, Jesús B; Fernández, Marta S

2007-10-01

The effect of the excitation or emission wavelengths on Laurdan generalized polarization (GP) can be evaluated by GPS, a quantitative, simplified determination of the GP spectrum slope, the thermotropic dependence of which allows the assessment of phospholipid lamellar membrane phase, as shown in a recent publication of our laboratory [J.B. Velázquez, M.S. Fernández, Arch. Biochem. Biophys. 455 (2006) 163-174]. In the present work, we applied Laurdan GPS to phase transition studies of mixed, two-phosphatidylcholine liposomes prepared from variable proportions of dimyristoyl- and dipalmitoylphosphatidylcholine (DMPC and DPPC, respectively). We have found that the GPS function reports a clear limit between the gel/liquid-crystalline phase coexistence region and the liquid-crystalline state, not only at a certain temperature T(c) for liposomes of constant composition submitted to temperature scans, but also at a defined mole fraction X(c), for two-component liposomes of variable composition at constant temperature. The T(c) or the X(c) values obtained from GPS vs. temperature or GPS vs. composition plots, respectively, allow the construction of a partial phase diagram for the DMPC-DPPC mixtures, showing the boundary between the two-phase coexisting region and the liquid-crystalline state. Likewise, at the onset of the transition region, i.e., the two-phase coexisting region as detected by GPS, it is possible to determine, although with less precision, a temperature T(o) or a mole fraction X(o) defining a boundary located below but near the limit between the gel and ripple phase, reported in the literature. These GPS results are consistent with the proposal by several authors that a fraction of L(alpha) phospholipids coexists with gel phospholipids in the rippled phase.

Biphasic Synergistic Gel Materials with Switchable Mechanics and Self-Healing Capacity.

PubMed

Zhao, Ziguang; Liu, Yuxia; Zhang, Kangjun; Zhuo, Shuyun; Fang, Ruochen; Zhang, Jianqi; Jiang, Lei; Liu, Mingjie

2017-10-16

A fabrication strategy for biphasic gels is reported, which incorporates high-internal-phase emulsions. Closely packed micro-inclusions within the elastic hydrogel matrix greatly improve the mechanical properties of the materials. The materials exhibit excellent switchable mechanics and shape-memory performance because of the switchable micro- inclusions that are incorporated into the hydrogel matrix. The produced materials demonstrated a self-healing capacity that originates from the noncovalent effect of the biphasic heteronetwork. The aforementioned characteristics suggest that the biphasic gels may serve as ideal composite gel materials with validity in a variety of applications, such as soft actuators, flexible devices, and biological materials. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Porous Aromatic Framework 48/Gel Hybrid Material Coated Solid-Phase Microextraction Fiber for the Determination of the Migration of Styrene from Polystyrene Food Contact Materials.

PubMed

Jin, Yuanyuan; Li, Zhongyue; Yang, Lei; Xu, Jun; Zhao, Le; Li, Zhonghao; Niu, Jiajia

2017-01-17

A novel solid-phase microextraction (SPME) fiber was fabricated by a porous aromatic framework 48 (PAF-48)/gel hybrid material through a sol-gel process. PAF-48 is a porous organic framework (POF) material that was polymerized from 1,3,5-triphenylbenzene. The uniform pore structure, high surface area, continuous conjugate network, and hydrophobicity make PAF-48 expected to have special abilities to absorb and extract styrene as well as some other harmful volatile aromatic compounds (VACs). The PAF-48/gel-coated fiber was explored for the extraction of styrene and six VACs (benzene, toluene, ethylbenzene, and xylenes) from aqueous food simulants followed by gas chromatography (GC) separation. The fiber was found to be very sensitive for the determination of the target molecules with wide linear ranges (0.1-200 or 500 μg·kg -1 ), low limits of detection (LODs, 0.003-0.060 μg·kg -1 ), acceptable precisions (intraday relative standard deviation, RSD < 5.9%, interday RSD < 7.3%), and long lifetime (>200 times). Particularly for styrene, the PAF-48/gel-coated fiber exhibited a much lower LOD (0.006 μg·kg -1 ) compared with most of the reported fibers. Moreover, the PAF-48/gel-coated fiber had a high extraction selectivity for styrene and VACs over alcohols, phenols, aromatic amines, and alkanes and show a molecular sieving effect for the different molecule sizes. Finally, the PAF-48/gel-coated SPME fiber was successfully applied in GC for the determination of the specific migrations of styrene and VACs from polystyrene (PS) plastic food contact materials (FCMs).

Tretinoin Nanogel 0.025% Versus Conventional Gel 0.025% in Patients with Acne Vulgaris: A Randomized, Active Controlled, Multicentre, Parallel Group, Phase IV Clinical Trial

PubMed Central

Chandrashekhar, B S; Anitha, M.; Ruparelia, Mukesh; Vaidya, Pradyumna; Aamir, Riyaz; Shah, Sunil; Thilak, S; Aurangabadkar, Sanjeev; Pal, Sandeep; Saraswat, Abir

2015-01-01

Background: Conventional topical tretinoin formulation is often associated with local adverse events. Nanogel formulation of tretinoin has good physical stability and enables good penetration of tretinoin into the pilo-sebaceous glands. Aim: The present study was conducted to assess the efficacy and safety of a nanogel formulation of tretinoin as compared to its conventional gel formulation in the treatment of acne vulgaris of the face. Materials and Methods: This randomized, active controlled, multicentric, phase IV clinical trial evaluated the treatment of patients with acne vulgaris of the face by the two gel formulations locally applied once daily at night for 12 wk. Acne lesion counts (inflammatory, non-inflammatory & total) and severity grading were carried out on the monthly scheduled visits along with the tolerability assessments. Results: A total of 207 patients were randomized in the study. Reductions in the total (72.9% vs. 65.0%; p = 0.03) and inflammatory (78.1% vs. 66.9%; p = 0.02) acne lesions were reported to be significantly greater with the nanogel formulation as compared to the conventional gel formulation. Local adverse events were significantly less (p = 0.04) in the nanogel group (13.3%) as compared to the conventional gel group (24.7%). Dryness was the most common adverse event reported in both the treatment groups while peeling of skin, burning sensation and photosensitivity were reported in patients using the conventional gel only. Conclusion: In the treatment of acne vulgaris of the face, tretinoin nanogel formulation appears to be more effective and better tolerated than the conventional gel formulation. PMID:25738069

Chemical sensing of copper phthalocyanine sol-gel glass through organic vapors

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

Ridhi, R.; Gawri, Isha; Abbas, Saeed J.

2015-05-15

The sensitivities of metallophthalocyanine to vapor phase electron donors has gained significance in many areas and disciplines due to their sensing properties and ease of operation. In the present study the interaction mechanism of organic vapors in Copper Phthalocyanine (CuPc) sol-gel glass has been studied. The interaction mechanism is affected by many factors like morphology, electrical or optical properties of film. CuPc sol-gel glass has been synthesized using chemical route sol-gel method. Its structural characterization was conducted using XRD and the amorphous nature of the silicate glass was observed with characteristic α polymorph phase of CuPc at around 6.64° withmore » 13.30Å interplanar spacing. The size of the particle as determined using Debbye Scherre’s formula comes out around 15.5 nm. The presence of α phase of CuPc was confirmed using FTIR with the appearance of crystal parameter marker band at 787 cm-1. Apart from this A2u and Eu symmetry bands of CuPc have also been observed. The UV absorption spectrum of CuPc exhibits absorption peaks owing to π→ π* and n→ π* transitions. A blue shift in the prepared CuPc glass has been observed as compared to the dopant CuPc salt indicating increase of band gap. A split in B (Soret) band and Q band appears as observed with the help of Lorentzian fitting. CuPc sol gel glass has been exposed with chemical vapors of Methanol, Benzene and Bromine individually and the electrical measurements have been carried out. These measurements show the variation in conductivity and the interaction mechanism has been analyzed.« less

In situ analysis of phase transformation in sol-gel cogelified nanopowder mixture of Al 2O 3 and TiO 2 using synchrotron X-ray radiation diffraction experiments

NASA Astrophysics Data System (ADS)

Jianu, A.; Stanciu, L.; Groza, J. R.; Lathe, Ch.; Burkel, E.

2003-01-01

Aluminium titanate (Al 2TiO 5) has been selected for study due to its high melting point and thermal shock resistance. In situ analysis of phase transformation and of transformation kinetics of sol-gel powder mixture of alumina and titania cogelified samples was performed using high-temperature synchrotron radiation X-ray diffraction experiments. The high reactivity and molecular mixing of sol-gel cogelified precursor powders contributed to the evolution of the reaction. The stability of the TiO 2-tetragonal structure (anatase) increases due to Al 2O 3 presence. The temperature of the aluminium titanate endothermic reaction decreases when heating rate increases. The results obtained by in situ analysis have been used to establish the sintering parameters in order to obtain fully transformed, dense aluminium titanate bulk ceramics.

Wet powder processing of sol-gel derived mesoporous silica-hydroxyapatite hybrid powders.

PubMed

Andersson, Jenny; Johannessen, Espen; Areva, Sami; Järn, Mikael; Lindén, Mika

2006-08-01

This paper describes a method by which a porous silica coating layer can be obtained on different apatite particles through a simple sol-gel synthesis route. Sol-gel derived powders of hydroxyapatite (HAP) and beta tricalciumphosphate (beta-TCP) were coated with a mesoporous silica using C16TAB (hexadecyltrimethylammonium bromide) as a template in order to induce mesophase formation. Further calcination of the material removes the template from the mesophase and leaves a highly ordered hexagonal arranged mesoporous silica structure with a core of HAP/beta-TCP. The phase purity of the SiO2/apatite composites has been thoroughly investigated by the means of FT-IR, XRD, and solid state 31P MAS NMR. The phase purity of these materials is shown to be dependent on the solubility properties of the used apatites. The hybrid materials are suitable as a multifunctional biomaterial where osteoconductive properties can be combined with drug delivery.

Sintering and microstructure of silicon carbide ceramic with Y3Al5O12 added by sol-gel method*

PubMed Central

Guo, Xing-zhong; Yang, Hui

2005-01-01

Silicon carbide (SiC) ceramic with YAG (Y3Al5O12) additive added by sol-gel method was liquid-phase sintered at different sintering temperatures, and the sintering mechanism and microstructural characteristics of resulting silicon carbide ceramics were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and elemental distribution of surface (EDS). YAG (yttrium aluminum garnet) phase formed before the sintering and its uniform distribution in the SiC/YAG composite powder decreased the sintering temperature and improved the densification of SiC ceramic. The suitable sintering temperature was 1860 °C with the specimen sintered at this temperature having superior sintering and mechanical properties, smaller crystal size and fewer microstructure defects. Three characteristics of improved toughness of SiC ceramic with YAG added by sol-gel method were microstructural densification, main-crack deflection and crystal ‘bridging’. PMID:15682507

Sol-gel synthesis, phase composition, morphological and structural characterization of Ca10(PO4)6(OH)2: XRD, FTIR, SEM, 3D SEM and solid-state NMR studies

NASA Astrophysics Data System (ADS)

Kareiva, Simonas; Klimavicius, Vytautas; Momot, Aleksandr; Kausteklis, Jonas; Prichodko, Aleksandra; Dagys, Laurynas; Ivanauskas, Feliksas; Sakirzanovas, Simas; Balevicius, Vytautas; Kareiva, Aivaras

2016-09-01

Aqueous sol-gel chemistry route based on ammonium-hydrogen phosphate as the phosphorus precursor, calcium acetate monohydrate as source of calcium ions, and 1,2-ethylendiaminetetraacetic acid (EDTA), or 1,2-diaminocyclohexanetetracetic acid (DCTA), or tartaric acid (TA), or ethylene glycol (EG), or glycerol (GL) as complexing agents have been used to prepare calcium hydroxyapatite (Ca10(PO4)6(OH)2, CHAp). The phase transformations, composition, and structural changes in the polycrystalline samples were studied by infrared spectroscopy (FTIR), X-ray powder diffraction analysis (XRD), and scanning electron microscopy (SEM). The local short-range (nano- and mezo-) scale effects in CHAp were studied using solid-state NMR spectroscopy. The spatial 3D data from the SEM images of CHAp samples obtained by TA, EG and GL sol-gel routes were recovered for the first time to our knowledge.

Cultivation and energy efficient harvesting of microalgae using thermoreversible sol-gel transition

PubMed Central

Estime, Bendy; Ren, Dacheng; Sureshkumar, Radhakrishna

2017-01-01

Microalgae represent a promising source of renewable biomass for the production of biofuels and valuable chemicals. However, energy efficient cultivation and harvesting technologies are necessary to improve economic viability. A Tris-Acetate-Phosphate-Pluronic (TAPP) medium that undergoes a thermoreversible sol-gel transition is developed to efficiently culture and harvest microalgae without affecting the productivity as compared to that in traditional culture in a well-mixed suspension. After seeding microalgae in the TAPP medium in a solution phase at 15 °C, the temperature is increased by 7 °C to induce gelation. Within the gel, microalgae are observed to grow in large clusters rather than as isolated cells. The settling velocity of the microalgal clusters is approximately ten times larger than that of individual cells cultured in typical solution media. Such clusters are easily harvested gravimetrically by decreasing the temperature to bring the medium to a solution phase. PMID:28102313

Development of an on-line mixed-mode gel liquid chromatography×reversed phase liquid chromatography method for separation of water extract from Flos Carthami.

PubMed

Wang, Yu-Qing; Tang, Xu; Li, Jia-Fu; Wu, Yun-Long; Sun, Yu-Ying; Fang, Mei-Juan; Wu, Zhen; Wang, Xiu-Min; Qiu, Ying-Kun

2017-10-13

A novel on-line comprehensive two-dimensional liquid chromatography (2D-LC) method by coupling mixed-mode gel liquid chromatography (MMG-LC) with reversed phase liquid chromatography (RPLC) was developed. A mixture of 17 reference compounds was used to study the separation mechanism. A crude water extract of Flos Carthami was applied to evaluate the performance of the novel 2D-LC system. In the first dimension, the extract was eluted with a gradient of water/methanol over a cross-linked dextran gel Sephadex LH-20 column. Meanwhile, the advantages of size exclusion, reversed phase partition and adsorption separation mechanism were exploited before further on-line reversed phase purification on the second dimension. This novel on-line mixed-mode Sephadex LH-20×RPLC method provided higher peak resolution, sample processing ability (2.5mg) and better orthogonality (72.9%) versus RPLC×RPLC and hydrophilic interaction liquid chromatography (HILIC)×RPLC. To the best of our knowledge, this is the first report of a mixed-mode Sephadex LH-20×RPLC separation method with successful applications in on-line mode, which might be beneficial for harvesting targets from complicated medicinal plants. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of antimicrobial peptide on dynamics of phosphocholine membrane: role of cholesterol and physical state of bilayer

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

Sharma, Veerendra K.; Mamontov, Eugene; Anunciado, Divina B.

Antimicrobial peptides are universal in all forms of life and are well known for their strong interaction with the cell membrane. This makes them a popular target for investigation of peptide-lipid interactions. Here we report the effect of melittin, an important antimicrobial peptide, on the dynamics of membranes based on 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) lipid in both the solid gel and fluid phases. To probe the phase transition, elastic neutron intensity temperature scans have been carried out on DMPC-based unilamellar vesicles (ULV) with and without melittin. We have found that addition of a small amount (0.2 mol%) melittin eliminates the steep fallmore » in the elastic intensity at 296 K associated with the solid gel to fluid phase transition, which is observed for pure DMPC vesicles. Quasielastic neutron scattering (QENS) experiments have been carried out on DMPC ULV in the solid gel and fluid phases with and without 0.2 mol % melittin. The data analysis invariably shows the presence of lateral and internal motions of the DMPC molecule. We found that melittin does have a profound effect on the dynamics of lipid molecules, especially on the lateral motion, and affects it in a different way, depending on the phase of the bilayers. In the solid gel phase, it acts as a plasticizer, enhancing the lateral motion of DMPC. However, in the fluid phase it acts as a stiffening agent, restricting the lateral motion of the lipid molecules. These observations are consistent with the mean squared displacements extracted from the elastic intensity temperature scans. Cholesterol is a vital component of eukaryotic membrane, which is a natural target for melittin. To investigate the effect of melittin on vesicles supplemented with cholesterol, QENS experiments have also been carried out on DMPC ULV with 20 mol% cholesterol in the presence and absence of 0.2 mol% melittin. Remarkably, the effects of melittin on the membrane dynamics disappear in the presence of 20 mol % cholesterol. Thus, our measurements indicate that the destabilizing effect of the peptide melittin on membranes can be mitigated by the presence of cholesterol.« less

Effect of antimicrobial peptide on dynamics of phosphocholine membrane: role of cholesterol and physical state of bilayer

DOE PAGES

Sharma, Veerendra K.; Mamontov, Eugene; Anunciado, Divina B.; ...

2015-06-24

Antimicrobial peptides are universal in all forms of life and are well known for their strong interaction with the cell membrane. This makes them a popular target for investigation of peptide-lipid interactions. Here we report the effect of melittin, an important antimicrobial peptide, on the dynamics of membranes based on 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) lipid in both the solid gel and fluid phases. To probe the phase transition, elastic neutron intensity temperature scans have been carried out on DMPC-based unilamellar vesicles (ULV) with and without melittin. We have found that addition of a small amount (0.2 mol%) melittin eliminates the steep fallmore » in the elastic intensity at 296 K associated with the solid gel to fluid phase transition, which is observed for pure DMPC vesicles. Quasielastic neutron scattering (QENS) experiments have been carried out on DMPC ULV in the solid gel and fluid phases with and without 0.2 mol % melittin. The data analysis invariably shows the presence of lateral and internal motions of the DMPC molecule. We found that melittin does have a profound effect on the dynamics of lipid molecules, especially on the lateral motion, and affects it in a different way, depending on the phase of the bilayers. In the solid gel phase, it acts as a plasticizer, enhancing the lateral motion of DMPC. However, in the fluid phase it acts as a stiffening agent, restricting the lateral motion of the lipid molecules. These observations are consistent with the mean squared displacements extracted from the elastic intensity temperature scans. Cholesterol is a vital component of eukaryotic membrane, which is a natural target for melittin. To investigate the effect of melittin on vesicles supplemented with cholesterol, QENS experiments have also been carried out on DMPC ULV with 20 mol% cholesterol in the presence and absence of 0.2 mol% melittin. Remarkably, the effects of melittin on the membrane dynamics disappear in the presence of 20 mol % cholesterol. Thus, our measurements indicate that the destabilizing effect of the peptide melittin on membranes can be mitigated by the presence of cholesterol.« less

Lithium ion conduction in sol-gel synthesized LiZr2(PO4)3 polymorphs

NASA Astrophysics Data System (ADS)

Kumar, Milind; Yadav, Arun Kumar; Anita, Sen, Somaditya; Kumar, Sunil

2018-04-01

Safety issue associated with the high flammability and volatility of organic electrolytes used in commercial rechargeable lithium ion batteries has led to significant attention to ceramic-based solid electrolytes. In the present study, lithium ion conduction in two polymorphs of LiZr2(PO4)3 synthesized via the sol-gel route has been investigated. Rietveld refinement of room temperature X-ray diffraction data of LiZr2(PO4)3 powders calcined at 900 °C and 1300 °C confirmed these to be the monoclinic phase with P21/n structure and rhombohedral phase with R3¯c structure, respectively. Increase in calcination temperature and resultant phase transformation improved the room temperature conductivity from 2.27×10-6 ohm-1m-1 for the monoclinic phase to 1.41×10-4 ohm-1m-1 for rhombohedral phase. Temperature dependence of conductivity was modeled using Arrhenius law and activation energy of ˜ 0.59 eV (for monoclinic phase) and ˜0.50 eV (for rhombohedral phase) were obtained.

Active liquid-crystal deflector and lens with Fresnel structure

NASA Astrophysics Data System (ADS)

Shibuya, Giichi; Yamano, Shohei; Yoshida, Hiroyuki; Ozaki, Masanori

2017-02-01

A new type of tunable Fresnel deflector and lens composed of liquid crystal was developed. Combined structure of multiple interdigitated electrodes and the high-resistivity (HR) layer implements the saw-tooth distribution of electrical potential with only the planar surfaces of the transparent substrates. According to the numerical calculation and design, experimental devices were manufactured with the liquid crystal (LC) material sealed into the sandwiched flat glass plates of 0.7 mm thickness with rubbed alignment layers set to an anti-parallel configuration. Fabricated beam deflector with no moving parts shows the maximum tilt angle of +/-1.3 deg which can apply for optical image stabilizer (OIS) of micro camera. We also discussed and verified their lens characteristics to be extended more advanced applications. Transparent interdigitated electrodes were concentrically aligned on the lens aperture with the insulator gaps under their boundary area. The diameter of the lens aperture was 30 mm and the total number of Fresnel zone was 100. Phase retardation of the beam wavefront irradiated from the LC lens device can be evaluated by polarizing microscope images with a monochromatic filter. Radial positions of each observed fringe are plotted and fitted with 2nd degree polynomial approximation. The number of appeared fringes is over 600 in whole lens aperture area and the correlation coefficients of all approximations are over 0.993 that seems enough ideal optical wavefront. The obtained maximum lens powers from the approximations are about +/-4 m-1 which was satisfied both convex and concave lens characteristics; and their practical use for the tunable lens grade eyeglasses became more prospective.

Stabilization of distearoylphosphatidylcholine lamellar phases in propylene glycol using cholesterol.

PubMed

Harvey, Richard D; Ara, Nargis; Heenan, Richard K; Barlow, David J; Quinn, Peter J; Lawrence, M Jayne

2013-12-02

Phospholipid vesicles (liposomes) formed in pharmaceutically acceptable nonaqueous polar solvents such as propylene glycol are of interest in drug delivery because of their ability to improve the bioavailability of drugs with poor aqueous solubility. We have demonstrated a stabilizing effect of cholesterol on lamellar phases formed by dispersion of distearoylphosphatidylcholine (DSPC) in water/propylene glycol (PG) solutions with glycol concentrations ranging from 0 to 100%. The stability of the dispersions was assessed by determining the effect of propylene glycol concentration on structural parameters of the lamellar phases using a complementary combination of X-ray and neutron scattering techniques at 25 °C and in the case of X-ray scattering at 65 °C. Significantly, although stable lamellar phases (and liposomes) were formed in all PG solutions at 25 °C, the association of the glycol with the liposomes' lamellar structures led to the formation of interdigitated phases, which were not thermostable at 65 °C. With the addition of equimolar quantities of cholesterol to the dispersions of DSPC, stable lamellar dispersions (and indeed liposomes) were formed in all propylene glycol solutions at 25 °C, with the significant lateral phase separation of the bilayer components only detectable in propylene glycol concentrations above 60% (w/w). We propose that the stability of lamellar phases of the cholesterol-containing liposomes formed in propylene glycol concentrations of up to 60% (w/w) represent potentially very valuable drug delivery vehicles for a variety of routes of administration.

Nuclear radiation-warning detector that measures impedance

DOEpatents

Savignac, Noel Felix; Gomez, Leo S; Yelton, William Graham; Robinson, Alex; Limmer, Steven

2013-06-04

This invention is a nuclear radiation-warning detector that measures impedance of silver-silver halide on an interdigitated electrode to detect light or radiation comprised of alpha particles, beta particles, gamma rays, X rays, and/or neutrons. The detector is comprised of an interdigitated electrode covered by a layer of silver halide. After exposure to alpha particles, beta particles, X rays, gamma rays, neutron radiation, or light, the silver halide is reduced to silver in the presence of a reducing solution. The change from the high electrical resistance (impedance) of silver halide to the low resistance of silver provides the radiation warning that detected radiation levels exceed a predetermined radiation dose threshold.

Dielectrophoretic columnar focusing device

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

James, Conrad D; Galambos, Paul C; Derzon, Mark S

2010-05-11

A dielectrophoretic columnar focusing device uses interdigitated microelectrodes to provide a spatially non-uniform electric field in a fluid that generates a dipole within particles in the fluid. The electric field causes the particles to either be attracted to or repelled from regions where the electric field gradient is large, depending on whether the particles are more or less polarizable than the fluid. The particles can thereby be forced into well defined stable paths along the interdigitated microelectrodes. The device can be used for flow cytometry, particle control, and other process applications, including cell counting or other types of particle counting,more » and for separations in material control.« less

One-Dimensional Contact Mode Interdigitated Center of Pressure Sensor (CMIPS)

NASA Technical Reports Server (NTRS)

Xu, Tian-Bing; Kang, Jinho; Park, Cheol; Harrison, Joycelyn S.; Guerreiro, Nelson M.; Hubbard, James E.

2009-01-01

A one dimensional contact mode interdigitated center of pressure sensor (CMIPS) has been developed. The experimental study demonstrated that the CMIPS has the capability to measure the overall pressure as well as the center of pressure in one dimension, simultaneously. A theoretical model for the CMIPS is established here based on the equivalent circuit of the configuration of the CMIPS as well as the material properties of the sensor. The experimental results match well with theoretical modeling predictions. A system mapped with two or more pieces of the CMIPS can be used to obtain information from the pressure distribution in multi-dimensions.

OPTOELECTRONICS, FIBER OPTICS, AND OTHER ASPECTS OF QUANTUM ELECTRONICS: Integrated-optical spectrum analyzer based on Ti:LiNbO3 with an optimized system of interdigital transducers and spherical geodesic lenses

NASA Astrophysics Data System (ADS)

Golovanova, T. M.; Gryaznov, Yu M.; Dianov, Evgenii M.; Dobryakova, N. G.; Kiselev, A. V.; Prokhorov, A. M.; Shcherbakov, E. A.

1989-08-01

An investigation was made of the parameters of an integrated-optical spectrum analyzer consisting of a Ti:LiNbO3 crystal and a semiconductor laser with a built-in microobjective, spherical geodesic lenses, and an optimized system of interdigital (opposed-comb) transducers. The characteristics of this spectrum analyzer were as follows: the band of operating frequencies was 181 MHz (at the 3 dB level); the resolution was 2.8 MHz; the signal/noise ratio (under a control voltage of 4 V) was 20 dB.

Simulation of optimum parameters for GaN MSM UV photodetector

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

Alhelfi, Mohanad A., E-mail: mhad12344@gmail.com; Ahmed, Naser M., E-mail: nas-tiji@yahoo.com; Hashim, M. R., E-mail: roslan@usm.my

2016-07-06

In this study the optimum parameters of GaN M-S-M photodetector are discussed. The evaluation of the photodetector depends on many parameters, the most of the important parameters the quality of the GaN film and others depend on the geometry of the interdigited electrode. In this simulation work using MATLAB software with consideration of the reflection and absorption on the metal contacts, a detailed study involving various electrode spacings (S) and widths (W) reveals conclusive results in device design. The optimum interelectrode design for interdigitated MSM-PD has been specified and evaluated by effect on quantum efficiency and responsivity.

Pilot Study of Bovine Interdigital Cassetteless Computed Radiography

PubMed Central

EL-SHAFAEY, El-Sayed Ahmed Awad; AOKI, Takahiro; ISHII, Mitsuo; YAMADA, Kazutaka

2013-01-01

ABSTRACT Twenty-one limbs of bovine cadavers (42 digits) were exposed to interdigital cassetteless imaging plate using computed radiography. The radiographic findings included exostosis, a rough planta surface, osteolysis of the apex of the distal phalanx and widening of the laminar zone between the distal phalanx and the hoof wall. All these findings were confirmed by computed tomography. The hindlimbs (19 digits) showed more changes than the forelimbs (10 digits), particularly in the lateral distal phalanx. The cassetteless computed radiography technique is expected to be an easily applicable method for the distal phalanx rather than a conventional cassette-plate and/or the film-screen cassetteless methods. PMID:23782542

Micromachined low frequency rocking accelerometer with capacitive pickoff

DOEpatents

Lee, Abraham P.; Simon, Jonathon N.; McConaghy, Charles F.

2001-01-01

A micro electro mechanical sensor that uses capacitive readout electronics. The sensor involves a micromachined low frequency rocking accelerometer with capacitive pickoff fabricated by deep reactive ion etching. The accelerometer includes a central silicon proof mass, is suspended by a thin polysilicon tether, and has a moving electrode (capacitor plate or interdigitated fingers) located at each end the proof mass. During movement (acceleration), the tethered mass moves relative to the surrounding packaging, for example, and this defection is measured capacitively by a plate capacitor or interdigitated finger capacitor, having the cooperating fixed electrode (capacitor plate or interdigitated fingers) positioned on the packaging, for example. The micromachined rocking accelerometer has a low frequency (<500 Hz), high sensitivity (.mu.G), with minimal power usage. The capacitors are connected to a power supply (battery) and to sensor interface electronics, which may include an analog to digital (A/D) converter, logic, RF communication link, antenna, etc. The sensor (accelerometer) may be, for example, packaged along with the interface electronics and a communication system in a 2".times.2".times.2" cube. The proof mass may be asymmetric or symmetric. Additional actuating capacitive plates may be used for feedback control which gives a greater dynamic range.

Electrical detection of DNA hybridization: three extraction techniques based on interdigitated Al/Al2O3 capacitors.

PubMed

Moreno-Hagelsieb, L; Foultier, B; Laurent, G; Pampin, R; Remacle, J; Raskin, J-P; Flandre, D

2007-04-15

Based on interdigitated aluminum electrodes covered with Al(2)O(3) and silver precipitation via biotin-antibody coupled gold nano-labels as signal enhancement, three complementary electrical methods were used and compared to detect the hybridization of target DNA for concentrations down to the 50 pM of a PCR product from cytochrome P450 2b2 gene. Human hepatic cytochrome P450 (CYP) enzymes participate in detoxification metabolism of xenobiotics. Therefore, determination of mutational status of P450 gene in a patient could have a significant impact on the choice of a medical treatment. Our three electrical extraction procedures are performed on the same interdigitated capacitive sensor lying on a passivated silicon substrate and consist in the measurement of respectively the low-frequency inter-electrodes capacitance, the high-frequency self-resonance frequency, and the equivalent MOS capacitance between the short-circuited electrodes and the backside metallization of the silicon substrate. This study is the first of its kind as it opens the way for correlation studies and noise reduction techniques based on multiple electrical measurements of the same DNA hybridization event with a single sensor.

Simulation of Electrostatic Actuation in Interdigitated Comb Drive MEMS Resonator for Energy Harvester Applications

NASA Astrophysics Data System (ADS)

Sathya, S.; Pavithra, M.; Muruganand, S.

2016-09-01

This paper presents an actuation mechanism based on the interdigitated comb drive MEMS resonator. The important role of that device is to establish MEMS resonators for the second order systems. Comb drive model is one of the basic model which uses the principle of electrostatic and force can be generated for the capacitive sensors. This work is done by overlapping movable and fixed comb fingers which produces an energy. The specific range of the polyimide material properties of young's modulus of 3.1GPa and density of 1300 Kg/m3. Results are shown in the structural domain performance of a lateral motion which corresponds to the applying voltage between the interdigitated comb fingers. It has laterally driven about 40pm with driving voltage. Also the resonance frequency 24Hz and 15Hz with high quality factors are depending on the spring length 260pm and 360pm and structure thickness of 2μm and 5 μm. Here Finite element method (FEM) is used to simulate the various physics scenario and it is designed as two dimensional structure multiphysics domain. The prototype of comb drive MEMS resonator has been suitable for energy harvesting system applications.

Functional deficits in carpal tunnel syndrome reflect reorganization of primary somatosensory cortex

PubMed Central

Kettner, Norman; Holden, Jameson; Lee, Jeungchan; Kim, Jieun; Cina, Stephen; Malatesta, Cristina; Gerber, Jessica; McManus, Claire; Im, Jaehyun; Libby, Alexandra; Mezzacappa, Pia; Morse, Leslie R.; Park, Kyungmo; Audette, Joseph; Tommerdahl, Mark; Napadow, Vitaly

2014-01-01

Carpal tunnel syndrome, a median nerve entrapment neuropathy, is characterized by sensorimotor deficits. Recent reports have shown that this syndrome is also characterized by functional and structural neuroplasticity in the primary somatosensory cortex of the brain. However, the linkage between this neuroplasticity and the functional deficits in carpal tunnel syndrome is unknown. Sixty-three subjects with carpal tunnel syndrome aged 20–60 years and 28 age- and sex-matched healthy control subjects were evaluated with event-related functional magnetic resonance imaging at 3 T while vibrotactile stimulation was delivered to median nerve innervated (second and third) and ulnar nerve innervated (fifth) digits. For each subject, the interdigit cortical separation distance for each digit’s contralateral primary somatosensory cortex representation was assessed. We also evaluated fine motor skill performance using a previously validated psychomotor performance test (maximum voluntary contraction and visuomotor pinch/release testing) and tactile discrimination capacity using a four-finger forced choice response test. These biobehavioural and clinical metrics were evaluated and correlated with the second/third interdigit cortical separation distance. Compared with healthy control subjects, subjects with carpal tunnel syndrome demonstrated reduced second/third interdigit cortical separation distance (P < 0.05) in contralateral primary somatosensory cortex, corroborating our previous preliminary multi-modal neuroimaging findings. For psychomotor performance testing, subjects with carpal tunnel syndrome demonstrated reduced maximum voluntary contraction pinch strength (P < 0.01) and a reduced number of pinch/release cycles per second (P < 0.05). Additionally, for four-finger forced-choice testing, subjects with carpal tunnel syndrome demonstrated greater response time (P < 0.05), and reduced sensory discrimination accuracy (P < 0.001) for median nerve, but not ulnar nerve, innervated digits. Moreover, the second/third interdigit cortical separation distance was negatively correlated with paraesthesia severity (r = −0.31, P < 0.05), and number of pinch/release cycles (r = −0.31, P < 0.05), and positively correlated with the second and third digit sensory discrimination accuracy (r = 0.50, P < 0.05). Therefore, reduced second/third interdigit cortical separation distance in contralateral primary somatosensory cortex was associated with worse symptomatology (particularly paraesthesia), reduced fine motor skill performance, and worse sensory discrimination accuracy for median nerve innervated digits. In conclusion, primary somatosensory cortex neuroplasticity for median nerve innervated digits in carpal tunnel syndrome is indeed maladaptive and underlies the functional deficits seen in these patients. PMID:24740988

Field-Induced Alignment of Polar Bent-Ccore Smectic A Liquid Crystals

NASA Astrophysics Data System (ADS)

Shen, Yongqiang; Goodhew, Lisa; Shao, Renfan; Maclennan, Joseph; Clark, Noel; Rudquist, Per

2014-03-01

The SmAPF phase is a promising phase modulator mode. To use the SmAPF materials for applications, we need to obtain uniform, large-area alignment of the samples. However, bent-core liquid crystals are notoriously difficult to align with conventional surface treatment methods because most of them have no nematic phase. We have developed a powerful, new method using in-plane applied electric fields that allows us to create a perfect bookshelf alignment of orthogonal bent-core smectics. By using an interdigitated, finger-like electrode arrangement on one of the cell surfaces, we can align the materials by applying in-plane electric fields. This stripe geometry, which produces curved field lines, allows for only one smectic layer orientation, normal both to the cell walls and to the finger electrodes. After alignment, the cell can be operated in the conventional way by connecting the finger electrodes together to make one effective electrode, opposing continuous, common electrode on the opposite side of the cell. This alignment method opens up the use of these materials in perfectly aligned cells for both amplitude and phase-only modulation applications. This work was supported by NSF MRSEC Grant No. DMR-0820579, by NSF Grant No. DMR-1008300, and by Swedish Research Council (VR) Grant No. 621-2009-3621.

Development of loteprednol etabonate-loaded cationic nanoemulsified in-situ ophthalmic gel for sustained delivery and enhanced ocular bioavailability.

PubMed

Patel, Nirav; Nakrani, Happy; Raval, Mihir; Sheth, Navin

2016-11-01

A novel cationic nanoemulsified in-situ ophthalmic gel of loteprednol etabonate (LE) was developed to improve the permeability and retention time of formulations for overall improvement of drug's ocular bioavability. Capryol 90 (oil phase), tween 80 (surfactant) and transcutol P (cosurfactant) was selected as formulation excipients to construct pseudoternary phase diagrams and nanoemulsion region was recognized from diagrams. Spontaneous emulsification method was used to manufacture LE nanoemulsion and it was optimized using 3 2 factorial design by considering the amount of oil and the ratio of surfactant to cosurfactant (S mix ) as independent variables and evaluated for various physicochemical properties. Optimized NE was dispersed in Poloxamer 407 and 188 solution to form nanoemulsified sols that were predictable to transform into in-situ gels at corneal temperature. Drug pharmacokinetics of sterilized optimized in situ NE gel, NE-ISG2 [0.69% w/w Capryol 90, 0.99%w/w S mix (3:1), 13% Poloxamer 407, 4% w/w Poloxamer 188] and marketed formulation were assessed in rabbit aqueous humor. The in-situ gels were clear, shear thinning in nature and displayed zero-order drug release kinetics. NE-ISG2 showed the minimum ocular irritation potential and significantly (p < 0.01) higher C max and AUC (0-10 h) , delayed T max , extended mean residence time and improved (2.54-fold times) bioavailability compared to marketed formulation.

Formulation Optimization and Ex Vivo and In Vivo Evaluation of Celecoxib Microemulsion-Based Gel for Transdermal Delivery.

PubMed

Cao, Mengyuan; Ren, Lili; Chen, Guoguang

2017-08-01

Celecoxib (CXB) is a poorly aqueous solubility sulfonamide non-steroidal anti-inflammatory drug (NSAID). Hence, the formulation of CXB was selected for solubilization and bioavailability. To find out suitable formulation for microemulsion, the solubility of CXB in triacetin (oil phase), Tween 80 (surfactant), and Transcutol-P (co-surfactant) was screened respectively and optimized by using orthogonal experimental design. The Km value and concentration of oil, S mix , and water were confirmed by pseudo-ternary phase diagram studies and central composite design. One percent carbopol 934 was added to form CXB microemulsion-based gel. The final formulation was evaluated for its appearance, pH, viscosity, stability, drug content determination, globule size, and zeta potential. Its ex vivo drug permeation and the in vivo pharmacokinetic was investigated. Further research was performed to ensure the safety and validity by skin irritation study and in vivo anti-inflammatory activity study. Ex vivo permeation study in mice was designed to compare permeation and transdermal ability between microemulsion formulation and conventional gel. The results revealed that optimized microemulsion-based gel gained higher permeation based on smaller globule size and high drug loading of microemulsion. Transdermal ability was also greatly improved. Bioavailability was compared to market Celebrex® by the in vivo pharmacokinetic study in rabbits. The results indicated that CXB microemulsion-based gel had better bioavailability than Celebrex®.

Modeling the effects of pH and ionic strength on swelling of anionic polyelectrolyte gels

NASA Astrophysics Data System (ADS)

Drozdov, A. D.; deClaville Christiansen, J.

2015-07-01

A constitutive model is developed for the elastic response of an anionic polyelectrolyte gel under swelling in water with an arbitrary pH and an arbitrary molar fraction of dissolved monovalent salt. A gel is treated as a three-phase medium consisting of a solid phase (polymer network), solvent (water), and solute (mobile ions). Transport of solvent and solute is thought of as their diffusion through the polymer network accelerated by an electric field formed by mobile and fixed ions and accompanied by chemical reactions (dissociation of functional groups attached to polymer chains and formation of ion pairs between bound charges and mobile counter-ions). Constitutive equations are derived by means of the free energy imbalance inequality for an arbitrary three-dimensional deformation with finite strains. These relations are applied to analyze equilibrium swelling diagrams on poly(acrylic acid) gel, poly(methacrylic acid) gel, and three composite hydrogels under water uptake in a bath (i) with a fixed molar fraction of salt and varied pH, and (ii) with a fixed pH and varied molar fraction of salt. To validate the ability of the model to predict observations quantitatively, material constants are found by matching swelling curves under one type of experimental conditions and results of simulation are compared with experimental data in the other type of tests.

Highly efficient gel-state dye-sensitized solar cells prepared using propionitrile and poly(vinylidene fluoride-co-hexafluoropropylene)

NASA Astrophysics Data System (ADS)

Venkatesan, Shanmuganathan; Hidayati, Noor; Liu, I.-Ping; Lee, Yuh-Lang

2016-12-01

Propionitrile (PPN) solvent based iodide/triiodide liquid-electrolyte is utilized to prepare highly efficient poly (vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) polymer gel electrolytes (PGEs) of dye-sensitized solar cells, aiming at improving the energy conversion efficiency as well as the stability of gel-state DSSCs. The concentrations effect of the PVdF-HFP on the properties of PGEs and the performance of the corresponding cells are studied. The results show that the in-situ gelation is performed for the PVdF-HFP concentration range of 8-18% at room temperature. However, increasing the concentration of polymer in the PGEs triggers a decrease in the diffusivity and conductivity of the PGEs, but an increase in the phase transition temperature of the PGEs. A high phase transition temperature is obtained for the PGEs with 18 wt% PVdF-HFP, which increase the long-term stability of the gel-state DSSC. By using the 18 wt% PVdF-HFP in the presence of 5 wt% TiO2 nanofillers (NFs), gel-state cells with an efficiency of 8.38% can be obtained, which is higher than that achieved by liquid-state cells (7.55%). After 1000 h test at room temperature (RT) and 50 °C, the cell can retain 96% and 82%, respectively, of its initial efficiency.

Compare the phase transition properties of VO2 films from infrared to terahertz range

NASA Astrophysics Data System (ADS)

Liang, Shan; Shi, Qiwu; Huang, Wanxia; Peng, Bo; Mao, Zhenya; Zhu, Hongfu

2018-06-01

VO2 with reversible semiconductor-metal phase transition properties is particularly available for the application in smart opto-electrical devices. However, there are rare reports on comparing its phase transition properties at different ranges. In this study, the VO2 films are designed with the similar crystalline structure and stoichiometry, but different morphologies by inorganic and organic sol-gel methods, and their phase transition characteristics are compared both at infrared and terahertz range. The results indicate that the VO2 film prepared by inorganic sol-gel method shows more compact nanostructure. It results in larger resistivity change, infrared and terahertz switching ratio in the VO2 film. Moreover, it presents that the phase transition intensity of VO2 film in terahertz range is more sensitive to its microstructure. This work is helpful for understanding the susceptibility of terahertz switching properties of VO2 to its microstructure. And it can provide insights for the applications of VO2 in terahertz smart devices.

Tolerability of clindamycin/tretinoin gel vs. tretinoin microsphere gel and adapalene gel.

PubMed

Leyden, James; Wortzman, Mitchell; Baldwin, Edward K

2009-04-01

Newer agents and formulations seek to improve the tolerability of topical retinoid therapy. Recently, a gel containing crystalline clindamycin 1.2% and tretinoin 0.025% (CLIN/RA) was approved by the U.S. Food and Drug Administration (FDA) for the treatment of treating mild-to-moderate acne. This single-center, randomized, evaluator-blind phase 1 study compared the tolerability of CLIN/RA to 0.1% tretinoin gel or 0.1% adapalene gel. Forty-five patients applied CLIN/RA once daily to one side of their face every day for 21 days. Patients were randomized to either tretinoin 0.1% (n = 23) or adapalene 0.1% (n = 22) on the contralateral side. A clinical evaluator assessed degree of erythema and scaling; patients provided subjective evaluations of burning, stinging, and itching. CLIN/RA was significantly better tolerated than was 0.1% tretinoin gel, as evidenced by significantly reduced erythema (P < 0.04), scaling (P < 0.03), itching (P < 0.02), burning (P < 0.03) and stinging (P < 0.04). A trend for greater erythema, scaling, and subjective discomfort for 0.1% adapalene gel compared to CLIN/RA was also evident.

Autologous Platelet-Poor Plasma Gel for Injection Laryngoplasty

PubMed Central

Woo, Seung Hoon; Kim, Jin Pyeong; Park, Jung Je; Chung, Phil-Sang

2013-01-01

Purpose To overcome the potential disadvantages of the use of foreign materials and autologous fat or collagen, we introduce here an autologous plasma gel for injection laryngoplasty. The purpose of this study was to present a new injection material, a plasma gel, and to discuss its clinical effectiveness. Materials and Methods From 2 mL of blood, the platelet poor serum layer was collected and heated at 100℃ for 12 min to form a plasma gel. The plasma gel was then injected into a targeted site; the safety and efficacy thereof were evaluated in 30 rats. We also conducted a phase I/II clinical study of plasma gel injection laryngoplasty in 11 unilateral vocal fold paralysis patients. Results The plasma gel was semi-solid and an easily injectable material. Of note, plasma gel maintains the same consistency for up to 1 year in a sealed bottle. However, exposure to room air causes the plasma gel to disappear within 1 month. In our animal study, the autologous plasma gel remained in situ for 6 months in animals with minimal inflammation. Clinical study showed that vocal cord palsy was well compensated for with the plasma gel in all patients at two months after injection with no significant complications. Jitter, shimmer, maximum, maximum phonation time (MPT) and mean voice handicap index (VHI) also improved significantly after plasma gel injection. However, because the injected plasma gel was gradually absorbed, 6 patients needed another injection, while the gel remained in place in 2 patients. Conclusion Injection laryngoplasty with autologous plasma gel may be a useful and safe treatment option for temporary vocal cord palsy. PMID:24142660

Material Properties of Matrix Lipids Determine Conformation and Intermolecular Reactivity of a Diacetylenic Phosphatidylcholine in the Lipid Bilayer

PubMed Central

Puri, Anu; Jang, Hyunbum; Yavlovich, Amichai; Masood, M. Athar; Veenstra, Timothy D.; Luna, Carlos; Aranda-Espinoza, Helim; Nussinov, Ruth; Blumenthal, Robert

2011-01-01

Photopolymerizable phospholipid DC8,9PC (1,2-bis-(tricosa-10,12-diynoyl)-sn-glycero-3-phosphocholine) exhibits unique assembly characteristics in the lipid bilayer. Due to the presence of the diacetylene groups, DC8,9PC undergoes polymerization upon UV (254 nm) exposure and assumes chromogenic properties. DC8,9PC photopolymerization in a gel phase matrix lipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) monitored by UV-VIS absorption spectroscopy occurred within 2 minutes after UV treatment, whereas no spectral shifts were observed when DC8,9PC was incorporated in a liquid phase matrix 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). Liquid chromatography-tandem mass spectrometry analysis showed a decrease in DC8,9PC monomer in both DPPC and POPC environments without any change in matrix lipids in UV-treated samples. Molecular Dynamics (MD) simulations of DPPC/DC8,9PC and POPC/DC8,9PC bilayers indicate that the DC8,9PC molecules adjust to the thickness of the matrix lipid bilayer. Furthermore, motions of DC8,9PC in the gel phase bilayer are more restricted than in the fluid bilayer. The restricted motional flexibility of DC8,9PC (in the gel phase) enables the reactive diacetylenes in individual molecules to align and undergo polymerization, whereas the unrestricted motions in the fluid bilayer restrict polymerization due to the lack of appropriate alignment of the DC8,9PC fatty acyl chains. Fluorescence microscopy data indicates homogenous distribution of the lipid probe 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-lissamine rhodamine B sulfonyl ammonium salt (N-Rh-PE) in POPC/DC8,9PC monolayers, but domain formation in DPPC/DC8,9PC monolayers. These results show that the DC8,9PC molecules cluster and assume the preferred conformation in the gel phase matrix for UV-triggered polymerization reaction. PMID:22053903

Fabrication of a novel nanocomposite based on sol-gel process for hollow fiber-solid phase microextraction of aflatoxins: B1 and B2, in cereals combined with high performane liquid chromatography-diode array detection.

PubMed

Es'haghi, Zarrin; Sorayaei, Hoda; Samadi, Fateme; Masrournia, Mahboubeh; Bakherad, Zohreh

2011-10-15

The new pre-concentration technique, hollow fiber-solid phase microextraction based on carbon nanotube reinforced sol-gel and liquid chromatography-photodiode array detection was applied to determination of aflatoxins B(1), B(2) (AFB(1), AFB(2)) in rice, peanut and wheat samples. This research provides an overview of trends related to synthesis of solid phase microextraction (SPME) sorbnents that improves the assay of aflatoxins as the semi-polar compounds in several real samples. It mainly includes summary and a list of the results for a simple carbon nanotube reinforced sol-gel in-fiber device. This device was used for extraction, pre-concentration and determination of aflatoxins B1, B2 in real samples. In this technique carbon nanotube reinforced sol was prepared by the sol-gel method via the reaction of phenyl trimethoxysilane (PTMS) with a basic catalyst (tris hydroxymethyl aminomethan). The influences of microextraction parameters such as pH, ageing time, carbon nanotube contents, desorption conditions, desorption solvent and agitation speed were investigated. Optimal HPLC conditions were: C(18) reversed phase column for separation, water-acetonitril-methanol (35:10:55) as the mobile phase and maximum wavelength for detection was 370 nm. The method was evaluated statistically and under optimized conditions, the detection limits for the analytes were 0.074 and 0.061 ng/mL for B1 and B2 respectively. Limit of quantification for B1 and B2 was 0.1 ng/mL too (n=7). The precisions were in the range of 2.829-2.976% (n=3), and linear ranges were within 0.1 and 400 ng/mL. The method was successfully applied to the analysis of cereals (peanut, wheat, rice) with the relative recoveries from 47.43% to 106.83%. Copyright © 2011 Elsevier B.V. All rights reserved.

Nanoscale Packing Differences in Sphingomyelin and Phosphatidylcholine Revealed by BODIPY Fluorescence in Monolayers: Physiological Implications

PubMed Central

2015-01-01

Phosphatidycholines (PC) with two saturated acyl chains (e.g., dipalmitoyl) mimic natural sphingomyelin (SM) by promoting raft formation in model membranes. However, sphingoid-based lipids, such as SM, rather than saturated-chain PCs have been implicated as key components of lipid rafts in biomembranes. These observations raise questions about the physical packing properties of the phase states that can be formed by these two major plasma membrane lipids with identical phosphocholine headgroups. To investigate, we developed a monolayer platform capable of monitoring changes in surface fluorescence by acquiring multiple spectra during measurement of a lipid force–area isotherm. We relied on the concentration-dependent emission changes of 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY)-labeled PC to detect nanoscale alterations in lipid packing and phase state induced by monolayer lateral compression. The BODIPY-PC probe contained an indacene ring with four symmetrically located methyl (Me) substituents to enhance localization to the lipid hydrocarbon region. Surface fluorescence spectra indicated changes in miscibility even when force–area isotherms showed no deviation from ideal mixing behavior in the surface pressure versus cross-sectional molecular area response. We detected slightly better mixing of Me4-BODIPY-8-PC with the fluid-like, liquid expanded phase of 1-palmitoyl-2-oleoyl-PC compared to N-oleoyl-SM. Remarkably, in the gel-like, liquid condensed phase, Me4-BODIPY-8-PC mixed better with N-palmitoyl-SM than dipalmitoyl-PC, suggesting naturally abundant SMs with saturated acyl chains form gel-like lipid phase(s) with enhanced ability to accommodate deeply embedded components compared to dipalmitoyl-PC gel phase. The findings reveal a fundamental difference in the lateral packing properties of SM and PC that occurs even when their acyl chains match. PMID:24564829

Self-assembly of gelator molecules in liquid crystals studied by ESR

NASA Astrophysics Data System (ADS)

Andreis, Mladen; Carić, Dejana; Vujičić, Nataša Šijaković; Jokić, Milan; Žinić, Mladen; Kveder, Marina

2012-07-01

Thermotropic liquid crystal trans-4-heptylcyclohexanecarboxylic acid (HCCA) doped with 4-oxo-2,2,6,6,-tetramethyl-1-piperidinyloxy spin probe (Tempone) is investigated by electron spin resonance (ESR) spectroscopy in the presence of chiral bisoxalamide gelator 1 during both cooling and heating cycles. In the temperature range 295-383 K, where HCCA displays isotropic, nematic, smectic B and crystalline phases, the impact of 1 self-organization was detected via (non) homogeneous partitioning of the spin probe in the environments varying in the polarity, an effect dependent on the gelator concentration. In particular, the evidence of the onset of the gelator network self-assembly in the nematic phase was detected by ESR at higher temperatures than the ones reported so far by other experimental techniques. Additionally, the spectral analysis points to the switching of the polarity in the vicinity of the spin probe when the transfer of chirality from 1 to HCCA upon cooling of the sample from isotropic to chiral nematic phase appears and when the event of LC gelation results in the achiral nematic phase during chiral gel fibers formation. When the gelation proceeds in the smectic phase, the melting of the gelator network is studied in the nematic phase during the heating cycle. Furthermore, the event of HCCA crystallization is shown to be strongly affected by the presence of 1 as well. The experimental evidence is provided that gelator network confines the HCCA into the domains within the bulk crystalline matrix where the local molecular dynamics are still not frozen. Therefore, we propose that non-homogeneous polarity profile of molecular organization/packing within LC gels could be determinable for the physical properties of various LC gel phases.

Novel benzo-15-crown-5 sol-gel coating for solid-phase microextraction.

PubMed

Wang, Danhua; Xing, Jun; Peng, Jiagang; Wu, Caiying

2003-07-11

A novel dihydroxy-terminated benzo-15-crown-5 was synthesized and applied to prepare a solid-phase microextraction (SPME) fiber coating with sol-gel technology. The optimization of the sol-gel process was studied. The coating method with sol-gel was improved and completed in one run, which economized materials and allowed easier control of the fiber thickness. The repeatability of coating fiber to fiber was better than 4.94% (RSD). The surface of the fiber coating was well-distributed and an electron microscopy experiment suggested a porous structure for crown ether coating, providing high surface areas and allowing for high extraction efficiency. The coating has a high thermal stability (350 degrees C), long lifetime and can stand solvent (organic and inorganic) rinsing due to the chemical binding between the coating and the fiber surface. Non-polar benzene, toluene, ethylbenzene, xylenes, chlorobenzenes, polar phenolic compounds and arylamines were used to evaluate the character of the fiber coating by headspace SPME-gas chromatography technology. For phenols, the linear concentrations ranged from 5 to 1000 microg/l, the detection limits were between 0.05 and 1 microg/l, and the RSD was less than 5%. The addition of benzo-crown ether not only increases the thermal stability of the fiber coating, but also enhances the selectivity of the fiber coating. Compared with commercially available SPME fibers poly(dimethylsiloxane) and polyacrylate, the few phases showed better selectivity and sensitivity towards non-polar and polar aromatic compounds.

Responsive hydrogels--structurally and dimensionally optimized smart frameworks for applications in catalysis, micro-system technology and material science.

PubMed

Döring, Artjom; Birnbaum, Wolfgang; Kuckling, Dirk

2013-09-07

Although the technological and scientific importance of functional polymers has been well established over the last few decades, the most recent focus that has attracted much attention has been on stimuli-responsive polymers. This group of materials is of particular interest due to its ability to respond to internal and/or external chemico-physical stimuli, which is often manifested as large macroscopic responses. Aside from scientific challenges of designing stimuli-responsive polymers, the main technological interest lies in their numerous applications ranging from catalysis through microsystem technology and chemomechanical actuators to sensors that have been extensively explored. Since the phase transition phenomenon of hydrogels is theoretically well understood advanced materials based on the predictions can be prepared. Since the volume phase transition of hydrogels is a diffusion-limited process the size of the synthesized hydrogels is an important factor. Consistent downscaling of the gel size will result in fast smart gels with sufficient response times. In order to apply smart gels in microsystems and sensors, new preparation techniques for hydrogels have to be developed. For the up-coming nanotechnology, nano-sized gels as actuating materials would be of great interest.

Molecular gels in the gas phase? Gelator-gelator and gelator-solvent interactions probed by vibrational spectroscopy.

PubMed

Lozada-Garcia, Rolando; Mu, Dan; Plazanet, Marie; Çarçabal, Pierre

2016-08-10

Benzylidene glucose (BzGlc) is a member of the benzylidene glycoside family. These molecules have the ability to form molecular physical gels. These materials are formed when gelator molecules create a non-covalently bound frame where solvent molecules are trapped. Since the gel formation process and its properties are determined by the subtle balance between non-covalent forces, it is difficult to anticipate them. Quantitative and qualitative understanding of the gelator-gelator and gelator-solvent interactions is needed to better control these materials for important potential applications. We have used gas phase vibrational spectroscopy and theoretical chemistry to study the conformational choices of BzGlc, its dimer and the complexes it forms with water or toluene. To interpret the vibrational spectra we have used the dispersion corrected functional B97D which we have calibrated for the calculation of OH stretching frequencies. Even at the most basic molecular level, it is possible to interrogate a large range of non-covalent interactions ranging from OH → OH hydrogen bonding, to OH → π, and CH → π, all being at the center of gel properties at the macroscopic level.

Phase study of titanium dioxide nanoparticle prepared via sol-gel process

NASA Astrophysics Data System (ADS)

Oladeji Araoyinbo, Alaba; Bakri Abdullah, Mohd Mustafa Al; Salleh, Mohd Arif Anuar Mohd; Aziz, Nurul Nadia Abdul; Iskandar Azmi, Azwan

2018-03-01

In this study, titanium dioxide nanoparticles have been prepared via sol-gel process using titanium tetraisopropoxide as a precursor with hydrochloric acid as a catalyst, and ethanol with deionized water as solvents. The value of pH used is set to 3, 7 and 8. The sols obtained were dried at 100 °C for 1 hr and calcined at 350, 550, and 750 °C for 3 hrs to observe the phase transformation of titanium dioxide nanoparticle. The samples were characterized by x-ray diffraction and field emission scanning electron microscope. The morphology analysis is obtained from field emission scanning electron microscope. The phase transformation was investigated by x-ray diffraction. It was found that the pH of the solution affect the agglomeration of titanium dioxide particle. The x-ray diffraction pattern of titanium dioxide shows the anatase phase most abundant at temperature of 350 °C. At temperature of 550 °C the anatase and rutile phase were present. At temperature of 750 °C the rutile phase was the most abundant for pH 3, 7 and 8. It was confirmed that at higher temperature the rutile phase which is the stable phase are mostly present.

A multiphase transitioning peptide hydrogel for suturing ultrasmall vessels

NASA Astrophysics Data System (ADS)

Smith, Daniel J.; Brat, Gabriel A.; Medina, Scott H.; Tong, Dedi; Huang, Yong; Grahammer, Johanna; Furtmüller, Georg J.; Oh, Byoung Chol; Nagy-Smith, Katelyn J.; Walczak, Piotr; Brandacher, Gerald; Schneider, Joel P.

2016-01-01

Many surgeries are complicated by the need to anastomose, or reconnect, micrometre-scale vessels. Although suturing remains the gold standard for anastomosing vessels, it is difficult to place sutures correctly through collapsed lumen, making the procedure prone to failure. Here, we report a multiphase transitioning peptide hydrogel that can be injected into the lumen of vessels to facilitate suturing. The peptide, which contains a photocaged glutamic acid, forms a solid-like gel in a syringe and can be shear-thin delivered to the lumen of collapsed vessels (where it distends the vessel) and the space between two vessels (where it is used to approximate the vessel ends). Suturing is performed directly through the gel. Light is used to initiate the final gel-sol phase transition that disrupts the hydrogel network, allowing the gel to be removed and blood flow to resume. This gel adds a new tool to the armamentarium for micro- and supermicrosurgical procedures.

Optical detection of parasitic protozoa in sol-gel matrices

NASA Astrophysics Data System (ADS)

Livage, Jacques; Barreau, J. Y.; Da Costa, J. M.; Desportes, I.

1994-10-01

Whole cell parasitic protozoa have been entrapped within sol-gel porous silica matrices. Stationary phase promastigote cells of Leishmania donovani infantum are mixed with a silica sol before gelation occurs. They remain trapped within the growing oxide network and their cellular organization appears to be well preserved. Moreover protozoa retain their antigenic properties in the porous gel. They are still able to detect parasite specific antibodies in serum samples from infected patients via an enzyme linked immunosorbent assay (ELISA). Antigen- antibody associations occurring in the gel are optically detected via the reactions of a peroxidase conjugate with ortho-phenylenediamine leading to the formation of a yellow coloration. A clear-cut difference in optical density is measured between positive and negative sera. Such an entrapment of antigenic species into porous sol-gel matrices avoids the main problems due to non specific binding and could be advantageously used in diagnostic kits.

Thermo-responsive gels that absorb moisture and ooze water.

PubMed

Matsumoto, Kazuya; Sakikawa, Nobuki; Miyata, Takashi

2018-06-13

The water content of thermo-responsive hydrogels can be drastically altered by small changes in temperature because their polymer chains change from hydrophilic to hydrophobic above their low critical solution temperature (LCST). In general, such smart hydrogels have been utilized in aqueous solutions or in their wet state, and no attempt has been made to determine the phase-transition behavior of the gels in their dried states. Here we demonstrate an application of the thermo-responsive behavior of an interpenetrating polymer network (IPN) gel comprising thermo-responsive poly(N-isopropylacrylamide) and hydrophilic sodium alginate networks in their dried states. The dried IPN gel absorbs considerable moisture from air at temperatures below its LCST and oozes the absorbed moisture as liquid water above its LCST. These phenomena provide energy exchange systems in which moisture from air can be condensed to liquid water using the controllable hydrophilic/hydrophobic properties of thermo-responsive gels with a small temperature change.

STUDY ON SYNTHESIS AND EVOLUTION OF NANOCRYSTALLINE Mg4Ta2O9 BY AQUEOUS SOL-GEL PROCESS

NASA Astrophysics Data System (ADS)

Wu, H. T.; Yang, C. H.; Wu, W. B.; Yue, Y. L.

2012-06-01

Nanosized and highly reactive Mg4Ta2O9 were successfully synthesized by aqueous sol-gel method compared with conventional solid-state method. Ta-Mg-citric acid solution was first formed and then evaporated resulting in a dry gel for calcination in the temperature ranging from 600°C to 800°C for crystallization in oxygen atmosphere. The crystallization process from the gel to crystalline Mg4Ta2O9 was identified by thermal analysis and phase evolution of powders was studied using X-ray diffraction (XRD) technique during calcinations. Particle size and morphology were examined by transmission electron microscopy (TEM) and high resolution scanning electron microscopy (HR-SEM). The results revealed that sol-gel process showed great advantages over conventional solid-state method and Mg4Ta2O9 nanopowders with the size of 20-30 nm were obtained at 800°C.

Molecular-sieve chromatography and electrophoresis in polyacrylamide gels

PubMed Central

Morris, C. J. O. R.; Morris, Peggy

1971-01-01

1. The absolute electrophoretic mobilities of eight proteins have been measured at pH8.76, I 0.05, in polyacrylamide gels of 20 different compositions at 10°C. 2. The partition coefficients of these proteins have been determined chromatographically under the same conditions by using columns of granulated polyacrylamide gel prepared simultaneously. 3. The electrophoretic mobilities are an exponential function of the gel concentrations when the latter are corrected for water uptake. The constants of this function have been determined by curvefitting methods. They have been shown to be related to the free solution mobility and to the mean molecular radius respectively. 4. The reduced mobilities have been shown to be a linear function of the partition coefficients by statistical analyses. 5. The physical significance of the relation between electrophoretic mobility and chromatographic phase distribution in gel media is discussed in the context of these results. PMID:5135238

Solvent-free, supersoft and superelastic bottlebrush melts and networks

NASA Astrophysics Data System (ADS)

Daniel, William F. M.; Burdyńska, Joanna; Vatankhah-Varnoosfaderani, Mohammad; Matyjaszewski, Krzysztof; Paturej, Jarosław; Rubinstein, Michael; Dobrynin, Andrey V.; Sheiko, Sergei S.

2016-02-01

Polymer gels are the only viable class of synthetic materials with a Young's modulus below 100 kPa conforming to biological applications, yet those gel properties require a solvent fraction. The presence of a solvent can lead to phase separation, evaporation and leakage on deformation, diminishing gel elasticity and eliciting inflammatory responses in any surrounding tissues. Here, we report solvent-free, supersoft and superelastic polymer melts and networks prepared from bottlebrush macromolecules. The brush-like architecture expands the diameter of the polymer chains, diluting their entanglements without markedly increasing stiffness. This adjustable interplay between chain diameter and stiffness makes it possible to tailor the network's elastic modulus and extensibility without the complications associated with a swollen gel. The bottlebrush melts and elastomers exhibit an unprecedented combination of low modulus (~100 Pa), high strain at break (~1,000%), and extraordinary elasticity, properties that are on par with those of designer gels.

Novel and high-performance asymmetric micro-supercapacitors based on graphene quantum dots and polyaniline nanofibers.

PubMed

Liu, Wenwen; Yan, Xingbin; Chen, Jiangtao; Feng, Yaqiang; Xue, Qunji

2013-07-07

In comparison with graphene sheets, graphene quantum dots (GQDs) exhibit novel chemical/physical properties including nanometer-size, abundant edge defects, good electrical conductivity, high mobility, chemical inertia, stable photoluminescence and better surface grafting, making them promising for fabricating various novel devices. In the present work, an asymmetric micro-supercapacitor, using GQDs as negative active material and polyaniline (PANI) nanofibers as positive active material, is built for the first time by a simple and controllable two-step electro-deposition on interdigital finger gold electrodes. Electrochemical measurements reveal that the as-made GQDs//PANI asymmetric micro-supercapacitor has a more excellent rate capability (up to 1000 V s(-1)) than previously reported electrode materials, as well as faster power response capability (with a very short relaxation time constant of 115.9 μs) and better cycling stability after 1500 cycles in aqueous electrolyte. On this basis, an all-solid-state GQDs//PANI asymmetric micro-supercapacitor is fabricated using H3PO4-polyvinyl alcohol gel as electrolyte, which also exhibits desirable electrochemical capacitive performances. These encouraging results presented here may open up new insight into GQDs with highly promising applications in high-performance energy-storage devices, and further expand the potential applications of GQDs beyond the energy-oriented application of GQDs discussed above.

Sensitivity differences between microporous NaY and hierarchical ZSM-5 modified electrodes as ammonia gas sensor

NASA Astrophysics Data System (ADS)

Lisnawati, E.; Agustin, I.; Krisnandi, Y. K.; Triyono, D.

2017-07-01

The hierarchical ZSM-5 had been successfully synthesized with double template using a hydrotermal method and microporous NaY zeolite had been successfully synthesized using a sol-gel method. XRD pattern confirmed hat the as-synthesized materials were ZSM-5 and NaY zeolites. SEM images of ZSM-5 showed that it has a hexagonal shape, which can be called coffin type,and rough surface. The EDS elemental analysis gives Si/Al molar ratio of 24.2. On the other hand, NaY crystals were intergrown in cuboid shapes with Si/Al molar ratio of 2. ZSM-5 and NaY were coated onto the surface of Interdigitated Capacitor (IDC) pattern made of gold/silver/quartz through spin coating method. IDC, ZSM-5/IDC and NaY/IDC were tested using Electrochemical Impedance Spectroscopy (EIS) method. The composite has different sensitivity in range concentration of ammonia 20-300 ppm. IDC has no significant effect of the presence of various concentrations, NaY/IDC and ZSM-5/IDC composite have frequency 100 Hz with R2 = 0.8312 and R2 = 0.8037. The NaY/IDC has higher sensitivity compared toZSM-5/IDC, this could be caused by the higher polarity of NaY compared to ZSM-5 to attract ammonia.

A Theoretical and Experimental Comparison of 3-3 and 3-1 Mode Piezoelectric Microelectromechanical Systems (MEMS)

PubMed Central

Kim, Donghwan; Hewa-Kasakarage, Nishshanka; Hall, Neal A.

2014-01-01

Two piezoelectric transducer modes applied in microelectromechanical systems are (i) the 3-1 mode with parallel electrodes perpendicular to a vertical polarization vector, and (ii) the 3-3 mode which uses interdigitated (IDT) electrodes to realize an in-plane polarization vector. This study compares the two configurations by deriving a Norton equivalent representation of each approach – including expressions for output charge and device capacitance. The model is verified using a microfabricated device comprised of multiple epitaxial silicon beams with sol-gel deposited lead zirconate titanate at the surface. The beams have identical dimensions and are attached to a common moving element at their tip. The only difference between beams is electrode configuration – enabling a direct comparison. Capacitance and charge measurements verify the presented theory with high accuracy. The Norton equivalent representation is general and enables comparison of any figure of merit, including electromechanical coupling coefficient and signal to noise ratio. With respect to coupling coefficient, the experimentally validated theory in this work suggests that 3-3 mode IDT-electrode configurations offer the potential for modest improvements compared against 3-1 mode devices (less than 2×), and the only geometrical parameter affecting this ratio is the fill factor of the IDT electrode. PMID:25309041

Synthetic biological membrane with self organizing properties

DOEpatents

Firestone, Millicent A.; Tiede, David M.

2003-01-01

A mixture is provided which manifests a gel phase at a temperature higher than that in which the mixture manifests a liquid phase. The mixture is a combination of a lipid, a polymer-grafted phospholipid and a surfactant. It is biomimetic in nature and changes phases when subjected to one or a plurality of environmental stimuli.

Tissue Viscoelasticity Imaging Using Vibration and Ultrasound Coupler Gel

NASA Astrophysics Data System (ADS)

Yamakawa, Makoto; Shiina, Tsuyoshi

2012-07-01

In tissue diagnosis, both elasticity and viscosity are important indexes. Therefore, we propose a method for evaluating tissue viscoelasticity by applying vibration that is usually performed in elastography and using an ultrasound coupler gel with known viscoelasticity. In this method, we use three viscoelasticity parameters based on the coupler strain and tissue strain: the strain ratio as an elasticity parameter, and the phase difference and the normalized hysteresis loop area as viscosity parameters. In the agar phantom experiment, using these viscoelasticity parameters, we were able to estimate the viscoelasticity distribution of the phantom. In particular, the strain ratio and the phase difference were robust to strain estimation error.

A one-step in-situ assembly strategy to construct PEG@MOG-100-Fe shape-stabilized composite phase change material with enhanced storage capacity for thermal energy storage

NASA Astrophysics Data System (ADS)

Wang, Junyong; Andriamitantsoa, Radoelizo S.; Atinafu, Dimberu G.; Gao, Hongyi; Dong, Wenjun; Wang, Ge

2018-03-01

A novel in-situ assembly strategy has been developed to synthesis polyethylene glycol (PEG)@iron-benzenetricarboxylate metal-organic gel (MOG-100-Fe) shape-stabilized composite phase change materials by regulating metal-to-ligand ratio. The PEG@MOG-100-Fe was prepared by an ingenious introduction of PEG into the traditional sol-gel prepared MOG-100-Fe. The composite exhibited high heat storage density and thermal stability. The PEG loading content reached up to 92% without any leakage above its melting point. The heat storage density reaches to 152.88

Human and porcine immunoreactive gastric inhibitory polypeptides (IR-GIP) are not identical.

PubMed

Bacarese-Hamilton, A J; Adrian, T E; Bloom, S R

1984-03-12

Immunoreactive gastric inhibitory polypeptide (IR-GIP) from human and porcine intestine was quantified by radioimmunoassay and the molecular forms characterised by gel permeation and reverse-phase high pressure liquid chromatography (HPLC). Gel filtration revealed two major immunoreactive peaks corresponding to the previously described 5-kDa and 8-kDa molecular forms, which appeared similar in both species. Isocratic reverse-phase HPLC revealed that the major immunoreactive GIP peak (5-kDa) in the human tissue eluted earlier than the corresponding porcine molecular form, indicating the latter to be less hydrophobic. These findings suggest significant species differences between human and porcine GIP.

Characterisation of Sol-Gel Synthesis of Phase Pure CaTiO3 Nano Powders after Drying

NASA Astrophysics Data System (ADS)

Mallik, P. K.; Biswal, G.; Patnaik, S. C.; Senapati, S. K.

2015-02-01

According to a few recent studies, calcium titanate (CT) is a material that is similar to hydroxyapatite in biological properties. However, calcium titanate is not currently being used in the biomedical applications as to hydroxyapatite. The objective is to prepare nano calcium titanate powders from the equimolar solution of calcium oxide, ethanol and Titanium (IV) isopropoxide via sol-gel synthesis. The phase analysis and morphology of powder particles were studied by X-ray diffraction (XRD), while the composition and size of powder particles were determined by Transmission electron microscope (TEM) attached with energy dispersive x-ray spectrometer (EDS). As results, XRD confirm the presence of phase pure crystalline CaTiO3 after drying at 100°C for 24 hours, while TEM analysis confirms about 13 nm sizes of CaTiO3 particles and some agglomerated particle of 20-30 nm. Moreover, EDS analysis indicates that the approximately stoichiometric Ca/Ti ratio 1:1 was obtained in the CaTiO3 powders. Finally, it can be concluded that described sol-gel synthesis could be novel method for the production of nano CaTiO3 particles at lower temperature compared to any other methods of production.

Sol-Gel-Synthesis of Nanoscopic Complex Metal Fluorides

PubMed Central

Rehmer, Alexander; Scheurell, Kerstin; Scholz, Gudrun; Kemnitz, Erhard

2017-01-01

The fluorolytic sol-gel synthesis for binary metal fluorides (AlF3, CaF2, MgF2) has been extended to ternary and quaternary alkaline earth metal fluorides (CaAlF5, Ca2AlF7, LiMgAlF6). The formation and crystallization of nanoscopic ternary CaAlF5 and Ca2AlF7 sols in ethanol were studied by 19F liquid and solid state NMR (nuclear magnetic resonance) spectroscopy, as well as transmission electron microscopy (TEM). The crystalline phases of the annealed CaAlF5, Ca2AlF7, and LiMgAlF6 xerogels between 500 and 700 °C could be determined by X-ray powder diffraction (XRD) and 19F solid state NMR spectroscopy. The thermal behavior of un-annealed nanoscopic ternary and quaternary metal fluoride xerogels was ascertained by thermal analysis (TG/DTA). The obtained crystalline phases of CaAlF5 and Ca2AlF7 derived from non-aqueous sol-gel process were compared to crystalline phases from the literature. The corresponding nanoscopic complex metal fluoride could provide a new approach in ceramic and luminescence applications. PMID:29099086

A combined analysis of 2 randomized clinical studies of tretinoin gel 0.05% for the treatment of acne.

PubMed

Webster, Guy; Cargill, D Innes; Quiring, John; Vogelson, Cullen T; Slade, Herbert B

2009-03-01

Acne vulgaris is a widely prevalent skin disorder primarily treated with retinoids, which have been shown to cause skin irritation. This report describes the combined analysis of 2 similar phase 3 studies designed to evaluate the efficacy and safety of an aqueous gel formulation of tretinoin relative to its vehicle (both studies) and a marketed microsphere formulation of tretinoin (one study) for once-daily topical treatment of acne. Randomized participants 10 years and older with mild to moderate acne (N=1537) received tretinoin gel 0.05% (n=674), tretinoin gel microsphere 0.1% (n=376), or vehicle (n=487) once daily for 12 weeks. Tretinoin gel was more effective than vehicle in reducing inflammatory (P<.001) and noninflammatory (P<.001) lesion counts over 12 weeks. Treatment success rate (global severity score, 0 or 1) was significantly greater in the tretinoin gel 0.05% group compared with the vehicle group (P<.001). The efficacy rate of tretinoin gel 0.05% was approximately 12% less than tretinoin gel microsphere 0.1%. Adverse events (AEs) were generally mild to moderate and rarely resulted in participant discontinuation. Incidence of skin-related AEs in the tretinoin gel 0.05% group (31%) was significantly lower compared with the tretinoin gel microsphere 0.1% group (52%)(P<.001). Thus, tretinoin gel 0.05% applied once daily is a well-tolerated and effective therapy for acne vulgaris and is associated with a low incidence of skin-related AEs.

Design and synthesis of inorganic/organic hybrid electrochemical materials

NASA Astrophysics Data System (ADS)

Harreld, John H.

An ambient pressure method for drying sol-gel materials is developed to synthesize high porosity (80--90%), high surface area vanadium oxide and silica aerogel materials (150--300 and 1000 m2/g for vanadium pentoxide and silica, respectively). The synthesis approach uses liquid exchange to replace the pore fluid with a low surface tension, nonpolar solvent which reduces the capillary pressures developed during drying. The Good-Girifalco interaction parameter is used to calculate pore stresses resulting from drying silica gels from various liquids. Vanadium oxide/polypyrrole hybrid aerogels are prepared using three strategies. These approaches focus on either sequential or consecutive polymerization of the inorganic and organic networks. Microcomposite aerogels are synthesized by encapsulating a dispersion of preformed polypyrrole in a vanadium pentoxide gel. In the second approach, pyrrole is polymerized and doped within the pore volume of preformed vanadium pentoxide gel. When the inorganic and organic precursors are polymerized simultaneously, the resulting gels exhibited a nanometer scaled microstructure with homogeneous distributions of either phases. Through this route, a suitable microstructure and composition for a lithium secondary battery cathode is obtained. Lithiated aerogels of hydrated nickel, cobalt, and mixed nickel-cobalt oxides are synthesized from lithium hydroxide and transition metal acetate precursors. The XRD analyses indicate that the nickel containing gels exhibit a lithium deficiency (less than 1 Li/transition metal. By increasing the concentration of the lithium precursor the lithium content in nickel oxides is increased, and additional base solution is no longer required to catalyze gelation. A non-hydrolytic sol-gel approach is utilized to create tin oxide and tin-aluminum binary oxide aerogels with high porosity (90%) and high surface area (300 m2/g). XRD data from single phase tin oxide aerogel indicates the growth of SnO2 crystallites between 150--400°C in air, accompanied by a reduction in surface area (30 m2/g). Heated tin oxide aerogel exhibits comparable reversible specific capacity (390 mAh/g) as that of commercial SnO2 (420 mAh/g). Amorphous tin oxide aerogel is stabilized to higher temperatures when aluminum oxide is incorporated into the structure. The tin oxide phase remains electrochemically active towards lithium insertion and exhibits excellent reversibility during cycling.

A gel probe equilibrium sampler for measuring arsenic porewater profiles and sorption gradients in sediments: I. Laboratory development

USGS Publications Warehouse

Campbell, K.M.; Root, R.; O'Day, P. A.; Hering, J.G.

2008-01-01

A gel probe equilibrium sampler has been developed to study arsenic (As) geochemistry and sorption behavior in sediment porewater. The gels consist of a hydrated polyacrylamide polymer, which has a 92% water content. Two types of gels were used in this study. Undoped (clear) gels were used to measure concentrations of As and other elements in sediment porewater. The polyacrylamide gel was also doped with hydrous ferric oxide (HFO), an amorphous iron (Fe) oxyhydroxide. When deployed in the field, HFO-doped gels introduce a fresh sorbent into the subsurface thus allowing assessment of in situ sorption. In this study, clear and HFO-doped gels were tested under laboratory conditions to constrain the gel behavior prior to field deployment. Both types of gels were allowed to equilibrate with solutions of varying composition and re-equilibrated in acid for analysis. Clear gels accurately measured solution concentrations (??1%), and As was completely recovered from HFO-doped gels (??4%). Arsenic speciation was determined in clear gels through chromatographic separation of the re-equilibrated solution. For comparison to speciation in solution, mixtures of As(III) and As(V) adsorbed on HFO embedded in gel were measured in situ using X-ray absorption spectroscopy (XAS). Sorption densities for As(III) and As(V) on HFO embedded in gel were obtained from sorption isotherms at pH 7.1. When As and phosphate were simultaneously equilibrated (in up to 50-fold excess of As) with HFO-doped gels, phosphate inhibited As sorption by up to 85% and had a stronger inhibitory effect on As(V) than As(III). Natural organic matter (>200 ppm) decreased As adsorption by up to 50%, and had similar effects on As(V) and As(III). The laboratory results provide a basis for interpreting results obtained by deploying the gel probe in the field and elucidating the mechanisms controlling As partitioning between solid and dissolved phases in the environment. ?? 2008 American Chemical Society.

Effect of annealing temperature on thermochromic properties of vanadium dioxide thin films deposited by organic sol-gel method

NASA Astrophysics Data System (ADS)

Wu, Jing; Huang, Wanxia; Shi, Qiwu; Cai, Jinghan; Zhao, Dong; Zhang, Yubo; Yan, Jiazhen

2013-03-01

This paper described the synthesis of vanadium dioxide (VO2) thin films on mica substrates with different annealing temperatures by an organic sol-gel method. We performed X-ray diffraction, scanning electron microscope and optical transmission measurements to investigate the effect of the annealing temperature on the crystalline structure, morphology, and phase transition properties of these films. The results showed that a polycrystalline structure with high crystallinity and compact surface at the annealing temperature of 500 °C. The film exhibited a V6O13 phase and a flat surface with small grain size at 440 °C. By contrast, the VnO2n-1 appeared when the annealing temperature at 540 °C, and the film surface split into segregation of spherical grain and aggregates of continuously dendritic particles. Accordingly, the optimal annealing temperature was 500 °C using the organic sol-gel method. And it turned out that the films mainly contained VO2 (M) phase at room temperature with high content of V4+ valence. Particularly, the films showed different changes in the infrared transmittance and hysteresis width during the phase transition. The largest transformation of the infrared transmittance before and after MIT was 73%, while the narrowest temperature hysteresis width was 8 °C at 500 °C.

Use of papain gel in disabled patients.

PubMed

Carrillo, C M; Tanaka, M H; Cesar, M F; Camargo, M A F; Juliano, Y; Novo, N F

2008-01-01

This study's purpose was to evaluate complete caries removal time (CCR) and patient acceptance of the chemomechanical caries removal agent and papain gel Papacárie in disabled patients. Fifty-one consecutive patients entered a prospective, controlled, randomized, open study. Patients were divided into 2 groups: (1) group 1=28 children 3 to 10 years old with or without visual or hearing impairments, motor disability on upper limbs, and inability to respond to simple orders; and (2) group 2=23 children, without visual or hearing impairments, with motor disability on the upper limbs and the ability to respond to simple orders. CCR time was measured in both groups. Patients' acceptance was assessed only in group 2 by using the visual analogy of face scale. The visual scale was presented in phase A--after the radiography with the child sitting on the dental chair before the beginning of the treatment, phase B--during the treatment, after total removal of the carious tissue and phase C--after the restoration was complete (treatment was finished). The total CCR average time was 8 minutes for each tooth when groups 1 and 2 were considered. Group 2 patients' acceptance in the first treatment was not statistically significant in all stages. Papacárie gel had a completed caries removal time of 8 minutes per tooth and is well accepted by the patients in all phases and in the first and subsequent visits.

Catoptric electrodes: transparent metal electrodes using shaped surfaces.

PubMed

Kik, Pieter G

2014-09-01

An optical electrode design is presented that theoretically allows 100% optical transmission through an interdigitated metallic electrode at 50% metal areal coverage. This is achieved by redirection of light incident on embedded metal electrode lines to an angle beyond that required for total internal reflection. Full-field electromagnetic simulations using realistic material parameters demonstrate 84% frequency-averaged transmission for unpolarized illumination across the entire visible spectral range using a silver interdigitated electrode at 50% areal coverage. The redirection is achieved through specular reflection, making it nonresonant and arbitrarily broadband, provided the electrode width exceeds the optical wavelength. These findings could significantly improve the performance of photovoltaic devices and optical detectors that require high-conductivity top contacts.

The Influence of Electrode and Channel Configurations on Flow Battery Performance

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

Darling, RM; Perry, ML

2014-05-21

Flow batteries with flow-through porous electrodes are compared to cells with porous electrodes adjacent to either parallel or interdigitated channels. Resistances and pressure drops are measured for different configurations to augment the electrochemical data. Cell tests are done with an electrolyte containing VO2+ and VO2+ in sulfuric acid that is circulated through both anode and cathode from a single reservoir. Performance is found to depend sensitively on the combination of electrode and flow field. Theoretical explanations for this dependence are provided. Scale-up of flow through and interdigitated designs to large active areas is also discussed. (C) 2014 The Electrochemical Society.more » All rights reserved.« less

Design architecture of double spiral interdigitated electrode with back gate electrode for biosensor application

NASA Astrophysics Data System (ADS)

Fathil, M. F. M.; Arshad, M. K. Md.; Hashim, U.; Ruslinda, A. R.; Gopinath, Subash C. B.; M. Nuzaihan M., N.; Ayub, R. M.; Adzhri, R.; Zaki, M.; Azman, A. H.

2016-07-01

This paper presents the preparation method of photolithography chrome mask design used in fabrication process of double spiral interdigitated electrode with back gate biasing based biosensor. By learning the fabrication process flow of the biosensor, the chrome masks are designed through drawing using the AutoCAD software. The overall width and length of the device is optimized at 7.0 mm and 10.0 mm, respectively. Fabrication processes of the biosensor required three chrome masks, which included back gate opening, spiral IDE formation, and passivation area formation. The complete chrome masks design will be sent for chrome mask fabrication and for future use in biosensor fabrication.

Fabrication and characterization of spiral interdigitated electrodes based biosensor for salivary glucose detection

NASA Astrophysics Data System (ADS)

Adelyn, P. Y. P.; Hashim, U.; Arshad, M. K. Md; Voon, C. H.; Liu, Wei-Wen; Kahar, S. M.; Huda, A. R. N.; Lee, H. Cheun

2017-03-01

This work introduces the non-invasive glucose monitoring technique by using the Complementary Metal Oxide Semiconductor (CMOS) technologically fabricated spiral Interdigitated Electrodes (IDE) based biosensor. Scanning Electron Microscopy (SEM) image explores the morphology of spiral IDE while Energy Dispersive X-Ray (EDX) determines the elements induced in spiral IDE. Oral saliva of two patients are collected and tested on the spiral IDE sensor with electrical characterization as glucose detection results. However, both patients exhibit their glucose level characteristics inconsistently. Therefore, this work could be extended and enhanced by adding Glutaraldehyde in between 3-Aminoproply)triethoxysilane (APTES) modified and glucose oxidase (GOD) enzyme immobilized layer with FTIR validation for bonding attachment.

Evaluation of carrier collection probability in bifacial interdigitated-back-contact crystalline silicon solar cells by the internal quantum efficiency mapping method

NASA Astrophysics Data System (ADS)

Tachibana, Tomihisa; Tanahashi, Katsuto; Mochizuki, Toshimitsu; Shirasawa, Katsuhiko; Takato, Hidetaka

2018-04-01

Bifacial interdigitated-back-contact (IBC) silicon solar cells with a high bifaciality of 0.91 were fabricated. Screen printing and firing technology were used to reduce the production cost. For the first time, the relationship between the rear side structure and carrier collection probability was evaluated using internal quantum efficiency (IQE) mapping. The measurement results showed that the screen-printed electrode and back surface field (BSF) area led to low IQE. The low carrier collection probability by BSF area can be explained by electrical shading effects. Thus, it is clear that the IQE mapping system is useful to evaluate the IBC cell.

Studies on a new class of organogelator containing 2-anthracenecarboxylic acid: influence of gelator and solvent on stereochemistry of the photodimers.

PubMed

Dawn, Arnab; Fujita, Norifumi; Haraguchi, Shuichi; Sada, Kazuki; Tamaru, Shun-ichi; Shinkai, Seiji

2009-11-07

A new class of binary organogelator (G1, G2 and G3) based on 2-anthracenecarboxylic acid (2Ac), attached noncovalently with the gelator counterpart containing a 3,4,5-tris(n-dodecyloxy)benzoylamide backbone has been developed. Among the three gelators, two (G2 and G3) are chiral containing D-alanine or L-2-phenylglycine moieties, respectively. They can act as efficient gelators of organic solvents with varying polarity depending upon the gelator systems. Gelator G1 even gelates chiral solvents. The photoirradiation of the gel samples produces photocyclodimers having different degrees of stereoselectivity for different systems. Gels with G1 and G2 produce head-to-head (h-h) photodimers as major products, whereas the stereoselectivity is reversed for the gels with G3 producing head-to-tail (h-t) photodimers as major products. Among those, G2/cyclohexane gel shows the highest degree of stereoselectivity, producing only h-h photodimers with some significant amount of chiral induction. Other chiral systems exhibit low to moderate chiral inductions. The gelator G1 can differentiate between the racemic and enantiomerically pure varieties of a solvent by exhibiting different gel melting temperatures (T(gel)). For different gel systems, T(gel) increases in all the cases as a consequence of photoreaction, except for the G2/cyclohexane gel, where a prominent gel-to-sol phase transition can be observed during the photoreaction. Hydrogen-bonding and pi-pi stacking interactions play the principal roles in constructing the gel structure. The morphologies of the gel systems vary between one-dimensional fibrils and a fibrillar network structure. In addition, the influences of the gelator and solvent polarity on the rate of photoreactions, photoproduct distributions as well as gel structures are investigated.

Current status of topical antiretroviral chemoprophylaxis.

PubMed

Van Damme, Lut; Szpir, Michael

2012-11-01

Recent studies suggest that the vaginal delivery of antiretroviral (ARV) agents - such as tenofovir, dapivirine and UC781 - may be a promising way to reduce the high rates of HIV infection among women in developing countries. This review examines these developments. The Microbicide Trials Network 003 study, a large phase IIb trial, was unable to show that daily dosing with 1% tenofovir vaginal gel was effective for HIV prevention. Nevertheless, preclinical and early-phase clinical trials suggest that ARV drugs - formulated in vaginal gels, rings, films, tablets and diaphragms - could be effective for HIV chemoprophylaxis. Investigations of topical chemoprophylaxis methods have seen mixed results in the past 12-18 months. Product adherence may prove to be one of the field's greatest challenges. Phase II and III trials continue to explore different dosing strategies for topical products that contain one or more ARV agents.

Solid-phase microextraction of methadone in urine samples by electrochemically co-deposited sol-gel/Cu nanocomposite fiber.

PubMed

Mohammadiazar, Sirwan; Hasanli, Fateme; Maham, Mehdi; Payami Samarin, Somayeh

2017-08-01

Electrochemically co-deposited sol-gel/Cu nanocomposites have been introduced as a novel, simple and single-step technique for preparation of solid-phase microextraction (SPME) coating to extract methadone (MDN) (a synthetic opioid) in urine samples. The porous surface structure of the sol-gel/Cu nanocomposite coating was revealed by scanning electron microscopy. Direct immersion SPME followed by HPLC-UV determination was employed. The factors influencing the SPME procedure, such as the salt content, desorption solvent type, pH and equilibration time, were optimized. The best conditions were obtained with no salt content, acetonitrile as desorption solvent type, pH 9 and 10 min equilibration time. The calibration graphs for urine samples showed good linearity. The detection limit was about 0.2 ng mL -1 . Also, the novel method for preparation of nanocomposite fiber was compared with previously reported techniques for MDN determination. The results show that the novel nanocomposite fiber has relatively high extraction efficiency. Copyright © 2016 John Wiley & Sons, Ltd.

Preparation of stir bars for sorptive extraction using sol-gel technology.

PubMed

Liu, Wenmin; Wang, Hanwen; Guan, Yafeng

2004-08-06

A sol-gel coating method for the preparation of extractive phase on bars used in sorptive microextraction is described. The extraction phase of poly(dimethylsiloxane) is partially crosslinked with the sol-gel network, and the most part is physically incorporated in the network. Three aging steps at different temperatures are applied to complete the crosslinking process. Thirty-micrometer-thick coating layer is obtained by one coating process. The improved coating shows good thermal stability up to 300 degrees C. Spiked aqueous samples containing n-alkanes, polycyclic aromatic hydrocarbons and organophosphorus pesticides were analyzed by using the sorptive bars and GC. The results demonstrate that it is suitable for both aploar and polar analytes. The detection limit for chrysene is 7.44 ng/L, 0.74 ng/L for C19 and 0.9 ng/L for phorate. The extraction equilibration can be reached in less than 15 min by supersonic extraction with the bars of 30 microm coating layer.

Successive changes in community structure of an ethylbenzene-degrading sulfate-reducing consortium.

PubMed

Nakagawa, Tatsunori; Sato, Shinya; Yamamoto, Yoko; Fukui, Manabu

2002-06-01

The microbial community structure and successive changes in a mesophilic ethylbenzene-degrading sulfate-reducing consortium were for the first time clarified by the denaturing gradient gel electrophoresis (DGGE) analysis of the PCR amplified 16S rRNA gene fragments. At least ten bands on the DGGE gel were detected in the stationary phase. Phylogenetic analysis of the DGGE bands revealed that the consortium consisted of different eubacterial phyla including the delta subgroup of Proteobacteria, the order Sphingobacteriales, the order Spirochaetales, and the unknown bacterium. The most abundant band C was closely related to strain mXyS1, an m-xylene-degrading sulfate-reducing bacterium (SRB), and occurred as a sole band on DGGE gels in the logarithmic growth phase that 40% ethylbenzene was consumed accompanied by sulfide production. During further prolonged incubation, the dominancy of band C did not change. These results suggest that SRB corresponds to the most abundant band C and contributes mainly to the degradation of ethylbenzene coupled with sulfate reduction.

Accelerated cell sheet detachment by copolymerizing hydrophilic PEG side chains into PNIPAm nanocomposite hydrogels.

PubMed

Liu, Dan; Wang, Tao; Liu, Xinxing; Tong, Zhen

2012-10-01

One-end-connected short poly(ethylene glycol) (PEG) side chains were facilely introduced into the poly(N-isopropylacrylamide) (PNIPAm) nanocomposite hydrogel (NC gel) via in situ copolymerization of NIPAm monomer and PEG macromonomer in the aqueous suspension of hectorite clay Laponite XLS. The NC gels were characterized with Fourier transform infrared and x-ray photoelectron spectroscopy for the composition, DSC and transmittance for the phase separation temperature, dynamic mechanical spectra and swelling ratio for the interaction. Increasing the PEG content led to a small increase in the storage modulus and the lower critical solution temperature (LCST) of the copolymerized NC gels, and the LCST of the copolymerized NC gels was still below 37 °C. The L929 cell adhesion and proliferation on the surface of these NC gels were not suppressed by the incorporation of hydrophilic PEG side chains. By lowering temperature below the LCST, the cell sheet spontaneously detached from the copolymerized NC gels. The surface morphology and surface wettability of the NC gels were detected by atom force microscope and contact angle measurement. A rough and hydrophilic surface induced by a small amount of PEG side chains was found to be favorable to accelerate the cell sheet detachment, probably due to the enhanced water permeation into the gel-cell sheet interface.

Characteristics of a gelled liquid hyprogen polyphenylene oxide (PPO) foam open-cell insulation system, phase 1

NASA Technical Reports Server (NTRS)

1973-01-01

A large scale gel production and storage facility and a small scale facility, the latter used for detailed visual examination of the gel/PPO foam interface, were developed. A subcontract was given to investigate techniques for the production of gelled liquid hydrogen, develop a process design for scale-up to a 1.89 cu m (500 gallon) gel production and storage facility, determine gel transfer characteristics, determine the solubility rate of gaseous helium in the gel, and investigate the gross gel/PPO foam interfacial phenomena. An inside-tank process for scaled-up production of gelled liquid hydrogen was selected. No detectable gel structure degradation occurred during repeated shearing. The viscosity of gelled liquid hydrogen at shear rates of 300/sec and higher is 2 to 5-fold greater than that of neat liquid hydrogen. No clogging problems were encountered during the transfer of gelled liquid hydrogen through warmed transfer lines. The solubility rate of helium in liquid hydrogen was significantly reduced by the presence of gel structure. The boil-off rates from gelled liquid hydrogen were reduced from 25 to 50 percent compared to those observed for the neat liquid hydrogen under compatible conditions. The polyphenylene oxide (PPO) foam insulation was found to be compatible with liquid ethane.