[Reversible first-degree atrioventricular block due to hyperthyroidism].

PubMed

Çelebi, Aksüyek Savaş; Amasyalı, Basri

2017-04-01

Hyperthyroidism often causes tachyarrhythmia. Reversible atrioventricular block caused by hyperthyroidism is rare occurrence. Presently described is a case of atrioventricular block due to hyperthyroidism and recovery after antithyroid treatment.

Achieving Continuous Anion Transport Domains Using Block Copolymers Containing Phosphonium Cations

DOE PAGES

Zhang, Wenxu; Liu, Ye; Jackson, Aaron C.; ...

2016-06-22

Triblock and diblock copolymers based on isoprene (Ip) and chloromethylstyrene (CMS) were synthesized in this paper by sequential polymerization using reversible addition–fragmentation chain transfer radical polymerization (RAFT). The block copolymers were quaternized with tris(2,4,6-trimethoxyphenyl)phosphine (Ar 3P) to prepare soluble ionomers. The ionomers were cast from chloroform to form anion exchange membranes (AEMs) with highly ordered morphologies. At low volume fractions of ionic blocks, the ionomers formed lamellar morphologies, while at moderate volume fractions (≥30% for triblock and ≥22% for diblock copolymers) hexagonal phases with an ionic matrix were observed. Ion conductivities were higher through the hexagonal phase matrix than inmore » the lamellar phases. Finally, promising chloride conductivities (20 mS/cm) were achieved at elevated temperatures and humidified conditions.« less

Meta-Analytic Evidence for a Reversal Learning Effect on the Iowa Gambling Task in Older Adults

PubMed Central

Pasion, Rita; Gonçalves, Ana R.; Fernandes, Carina; Ferreira-Santos, Fernando; Barbosa, Fernando; Marques-Teixeira, João

2017-01-01

Iowa Gambling Task (IGT) is one of the most widely used tools to assess economic decision-making. However, the research tradition on aging and the Iowa Gambling Task (IGT) has been mainly focused on the overall performance of older adults in relation to younger or clinical groups, remaining unclear whether older adults are capable of learning along the task. We conducted a meta-analysis to examine older adults' decision-making on the IGT, to test the effects of aging on reversal learning (45 studies) and to provide normative data on total and block net scores (55 studies). From the accumulated empirical evidence, we found an average total net score of 7.55 (±25.9). We also observed a significant reversal learning effect along the blocks of the IGT, indicating that older adults inhibit the prepotent response toward immediately attractive options associated with high losses, in favor of initially less attractive options associated with long-run profit. During block 1, decisions of older adults led to a negative gambling net score, reflecting the expected initial pattern of risk-taking. However, the shift toward more safe options occurred between block 2 (small-to-medium effect size) and blocks 3, 4, 5 (medium-to-large effect size). These main findings highlight that older adults are able to move from the initial uncertainty, when the possible outcomes are unknown, to decisions based on risk, when the outcomes are learned and may be used to guide future adaptive decision-making. PMID:29075222

Comparison of reversal with neostigmine of low-dose rocuronium vs. reversal with sugammadex of high-dose rocuronium for a short procedure.

PubMed

Choi, E S; Oh, A Y; Koo, B W; Hwang, J W; Han, J W; Seo, K S; Ahn, S H; Jeong, W J

2017-10-01

Some short procedures require deep neuromuscular blockade, which needs to be reversed at the end of the procedure. Forty-four patients undergoing elective laryngeal micro-surgery were randomly allocated into two groups: rocuronium 0.45 mg.kg -1 with neostigmine (50 μg.kg -1 with glycopyrrolate 10 μg.kg -1 ) reversal (moderate block group) vs. rocuronium 0.90 mg.kg -1 with sugammadex (4 mg.kg -1 ) reversal (deep block group). The primary outcome was the intubating conditions during laryngoscopy secondary outcomes included recovery of neuromuscular block; conditions for tracheal intubation; satisfaction score as determined by the surgeon; onset of neuromuscular block; and postoperative sore throat. The onset of neuromuscular block was more rapid, and intubation conditions and ease of intra-operative laryngoscopy were more favourable, and the satisfaction score was lower in the moderate block group compared with the deep block group. No difference was found in the incidence of postoperative sore throat. In laryngeal micro-surgery, the use of rocuronium 0.9 mg.kg -1 with sugammadex for reversal was associated with better surgical conditions and a shorter recovery time than rocuronium 0.45 mg.kg -1 with neostigmine. © 2017 The Association of Anaesthetists of Great Britain and Ireland.

The whole number axis integer linear transformation reversible information hiding algorithm on wavelet domain

NASA Astrophysics Data System (ADS)

Jiang, Zhuo; Xie, Chengjun

2013-12-01

This paper improved the algorithm of reversible integer linear transform on finite interval [0,255], which can realize reversible integer linear transform in whole number axis shielding data LSB (least significant bit). Firstly, this method use integer wavelet transformation based on lifting scheme to transform the original image, and select the transformed high frequency areas as information hiding area, meanwhile transform the high frequency coefficients blocks in integer linear way and embed the secret information in LSB of each coefficient, then information hiding by embedding the opposite steps. To extract data bits and recover the host image, a similar reverse procedure can be conducted, and the original host image can be lossless recovered. The simulation experimental results show that this method has good secrecy and concealment, after conducted the CDF (m, n) and DD (m, n) series of wavelet transformed. This method can be applied to information security domain, such as medicine, law and military.

Counting on the mental number line to make a move: sensorimotor ('pen') control and numerical processing.

PubMed

Sheridan, Rebecca; van Rooijen, Maaike; Giles, Oscar; Mushtaq, Faisal; Steenbergen, Bert; Mon-Williams, Mark; Waterman, Amanda

2017-10-01

Mathematics is often conducted with a writing implement. But is there a relationship between numerical processing and sensorimotor 'pen' control? We asked participants to move a stylus so it crossed an unmarked line at a location specified by a symbolic number (1-9), where number colour indicated whether the line ran left-right ('normal') or vice versa ('reversed'). The task could be simplified through the use of a 'mental number line' (MNL). Many modern societies use number lines in mathematical education and the brain's representation of number appears to follow a culturally determined spatial organisation (so better task performance is associated with this culturally normal orientation-the MNL effect). Participants (counter-balanced) completed two consistent blocks of trials, 'normal' and 'reversed', followed by a mixed block where line direction varied randomly. Experiment 1 established that the MNL effect was robust, and showed that the cognitive load associated with reversing the MNL not only affected response selection but also the actual movement execution (indexed by duration) within the mixed trials. Experiment 2 showed that an individual's motor abilities predicted performance in the difficult (mixed) condition but not the easier blocks. These results suggest that numerical processing is not isolated from motor capabilities-a finding with applied consequences.

Highly conductive side chain block copolymer anion exchange membranes.

PubMed

Wang, Lizhu; Hickner, Michael A

2016-06-28

Block copolymers based on poly(styrene) having pendent trimethyl styrenylbutyl ammonium (with four carbon ring-ionic group alkyl linkers) or benzyltrimethyl ammonium groups with a methylene bridge between the ring and ionic group were synthesized by reversible addition-fragmentation radical (RAFT) polymerization as anion exchange membranes (AEMs). The C4 side chain polymer showed a 17% increase in Cl(-) conductivity of 33.7 mS cm(-1) compared to the benzyltrimethyl ammonium sample (28.9 mS cm(-1)) under the same conditions (IEC = 3.20 meq. g(-1), hydration number, λ = ∼7.0, cast from DMF/1-propanol (v/v = 3 : 1), relative humidity = 95%). As confirmed by small angle X-ray scattering (SAXS), the side chain block copolymers with tethered ammonium cations showed well-defined lamellar morphologies and a significant reduction in interdomain spacing compared to benzyltrimethyl ammonium containing block copolymers. The chemical stabilities of the block copolymers were evaluated under severe, accelerated conditions, and degradation was observed by (1)H NMR. The block copolymer with C4 side chain trimethyl styrenylbutyl ammonium motifs displayed slightly improved stability compared to that of a benzyltrimethyl ammonium-based AEM at 80 °C in 1 M NaOD aqueous solution for 30 days.

Graphene-Based Reversible Nano-Switch/Sensor Schottky Diode

NASA Technical Reports Server (NTRS)

Miranda, Felix A.; Meador, Michael A.; Theofylaktos, Onoufrios; Pinto, Nicholas J.; Mueller, Carl H.; Santos-Perez, Javier

2010-01-01

This proof-of-concept device consists of a thin film of graphene deposited on an electrodized doped silicon wafer. The graphene film acts as a conductive path between a gold electrode deposited on top of a silicon dioxide layer and the reversible side of the silicon wafer, so as to form a Schottky diode. By virtue of the two-dimensional nature of graphene, this device has extreme sensitivity to different gaseous species, thereby serving as a building block for a volatile species sensor, with the attribute of having reversibility properties. That is, the sensor cycles between active and passive sensing states in response to the presence or absence of the gaseous species.

Neuromuscular Blockade and Reversal Agents: A Primer for Postanesthesia Nurses.

ERIC Educational Resources Information Center

Pesci, Barbara R.

1986-01-01

Presents a comprehensive review of neuromuscular blocking agents, reversal agents used in anesthesia, and factors affecting reversal. It is aimed at nurses who provide care to patients recovering from anesthesia. It discusses the neuromuscular transmission system, depolarizing muscle relaxants, nondepolarizing blocking agents, and criteria for…

Electrodiagnosis of reversible conduction failure in Guillain-Barré syndrome.

PubMed

Chan, Yee-Cheun; Punzalan-Sotelo, Aubrey M; Kannan, Therimadasamy A; Shahrizaila, Nortina; Umapathi, Thirugnanam; Goh, Eunice J H; Fukami, Yuki; Wilder-Smith, Einar; Yuki, Nobuhiro

2017-11-01

In this study we propose electrodiagnostic criteria for early reversible conduction failure (ERCF) in axonal Guillain-Barré syndrome (GBS) and apply them to a cohort of GBS patients. Serial nerve conduction studies (NCS) were retrospectively analyzed in 82 GBS patients from 3 centers. The criteria for the presence of ERCF in a nerve were: (i) a 50% increase in amplitude of distal compound muscle action potentials or sensory nerve action potentials; or (ii) resolution of proximal motor conduction block with an accompanying decrease in distal latencies or compound muscle action potential duration or increase in conduction velocities. Of 82 patients from 3 centers, 37 (45%) had ERCF, 21 (26%) had a contrasting evolution pattern, and 8 (10%) had both. Sixteen patients did not show an amplitude increase of at least 50%. Our proposed criteria identified a group of patients with a characteristic evolution of NCS abnormality that is consistent with ERCF. Muscle Nerve 56: 919-924, 2017. © 2017 Wiley Periodicals, Inc.

Low-affinity spermine block mediating outward currents through Kir2.1 and Kir2.2 inward rectifier potassium channels

PubMed Central

Ishihara, Keiko; Yan, Ding-Hong

2007-01-01

The outward component of the strong inward rectifier K+ current (IKir) plays a pivotal role in polarizing the membranes of excitable and non-excitable cells and is regulated by voltage-dependent channel block by internal cations. Using the Kir2.1 channel, we previously showed that a small fraction of the conductance susceptible only to a low-affinity mode of block likely carries a large portion of the outward current. To further examine the relevance of the low-affinity block to outward IKir and to explore its molecular mechanism, we studied the block of the Kir2.1 and Kir2.2 channels by spermine, which is the principal Kir2 channel blocker. Current–voltage relations of outward Kir2.2 currents showed a peak, a plateau and two peaks in the presence of 10, 1 and 0.1 μm spermine, respectively, which was explained by the presence of two conductances that differ in their susceptibility to spermine block. When the current–voltage relations showed one peak, like those of native IKir, outward Kir2.2 currents were mediated mostly by the conductance susceptible to the low-affinity block. They also flowed in a narrower range than the corresponding Kir2.1 currents, because of 3- to 4-fold greater susceptibility to the low-affinity block than in Kir2.1. Reducing external [K+] shifted the voltage dependences of both the high- and low-affinity block of Kir2.1 in parallel with the shift in the reversal potential, confirming the importance of the low-affinity block in mediating outward IKir. When Kir2.1 mutants known to have reduced sensitivity to internal blockers were examined, the D172N mutation in the transmembrane pore region made almost all of the conductance susceptible only to low-affinity block, while the E224G mutation in the cytoplasmic pore region reduced the sensitivity to low-affinity block without markedly altering that to the high-affinity block or the high/low conductance ratio. The effects of these mutations support the hypothesis that Kir2 channels exist in two states having different susceptibilities to internal cationic blockers. PMID:17640933

Evaluation of using ferrofluid as an interface material for a field-reversible thermal connector

NASA Astrophysics Data System (ADS)

Yousif, Ahmed S.

The electrical functionality of an avionics chassis is limited due to heat dissipation limits. The limits arise due to the fact that components in an avionic computer boxes are packed very compactly, with the components mounted onto plug-in cards, and the harsh environment experienced by the chassis limits how heat can be dissipated from the cards. Convective and radiative heat transfer to the ambient are generally not possible. Therefore it is necessary to have heat transferred from the components conducted to the edge of the plug-in cards. The heat then needs to conduct from the card edge to a cold block that not only holds the card in place, but also removes the generated heat by some heat transfer fluid that is circulated through the cold block. The interface between the plug-in card and the cold block typically has a high thermal resistance since it is necessary for the card to have the capability to be re-workable, meaning that the card can be removed and then returned to the chassis. Reducing the thermal resistance of the interface is the objective of the current study and the topic of this thesis. The current design uses a pressure interface between the card and cold block. The contact pressure is increased through the addition of a wedgelock, which is a field-reversible mechanical connector. To use a wedgelock, the cold block has channels milled on the surface with widths that are larger than the thickness of the plug-in card and the un-expanded wedgelock. The card edge is placed in the channel and placed against one of the channel walls. A wedgelock is then placed between the card and the other channel wall. The wedgelock is then expanded by using either a screw or a lever. As the wedgelock expands it fills in the remaining channel gap and bears against the other face of the plug-in card. The majority of heat generated by the components on the plug-in card is forced to conduct from the card into the wall of the cold block, effectively a single sided, dry conduction heat transfer path. Having started as a student design competition named RevCon Challenge, work was performed to evaluate the use of new field-reversible thermal connectors. The new design proposed by the University of Missouri utilized oil based iron nanoparticles, commonly known as a ferrofluid, as a thermal interface material. By using a liquid type of interface material the channel gap can be reduced to a few micrometers, within machining tolerances, and heat can be dissipated off both sides of the card. The addition of nanoparticles improves the effective thermal conductivity of base fluid. The use of iron nanoparticles allows magnets to be used to hold the fluid in place, so the electronic cards may be easily inserted and removed while keeping the ferrofluid in the cold block channel. The ferrofluid-based design which was investigated has shown lower thermal resistance than the current wedgelock design. These results open the door for further development of electronic cards by using higher heat emitting components without compromising the simplicity of attaching/detaching cards from cooling plates.

Absence of Rapid Propagation through the Purkinje Network as a Potential Cause of Line Block in the Human Heart with Left Bundle Branch Block.

PubMed

Okada, Jun-Ichi; Washio, Takumi; Nakagawa, Machiko; Watanabe, Masahiro; Kadooka, Yoshimasa; Kariya, Taro; Yamashita, Hiroshi; Yamada, Yoko; Momomura, Shin-Ichi; Nagai, Ryozo; Hisada, Toshiaki; Sugiura, Seiryo

2018-01-01

Background: Cardiac resynchronization therapy is an effective device therapy for heart failure patients with conduction block. However, a problem with this invasive technique is the nearly 30% of non-responders. A number of studies have reported a functional line of block of cardiac excitation propagation in responders. However, this can only be detected using non-contact endocardial mapping. Further, although the line of block is considered a sign of responders to therapy, the mechanism remains unclear. Methods: Herein, we created two patient-specific heart models with conduction block and simulated the propagation of excitation based on a cellmodel of electrophysiology. In one model with a relatively narrow QRS width (176 ms), we modeled the Purkinje network using a thin endocardial layer with rapid conduction. To reproduce a wider QRS complex (200 ms) in the second model, we eliminated the Purkinje network, and we simulated the endocardial mapping by solving the inverse problem according to the actual mapping system. Results: We successfully observed the line of block using non-contact mapping in the model without the rapid propagation of excitation through the Purkinje network, although the excitation in the wall propagated smoothly. This model of slow conduction also reproduced the characteristic properties of the line of block, including dense isochronal lines and fractionated local electrocardiograms. Further, simulation of ventricular pacing from the lateral wall shifted the location of the line of block. By contrast, in the model with the Purkinje network, propagation of excitation in the endocardial map faithfully followed the actual propagation in the wall, without showing the line of block. Finally, switching the mode of propagation between the two models completely reversed these findings. Conclusions: Our simulation data suggest that the absence of rapid propagation of excitation through the Purkinje network is the major cause of the functional line of block recorded by non-contact endocardial mapping. The line of block can be used to identify responders as these patients loose rapid propagation through the Purkinje network.

Electronic and Ionic Transport in Processable Conducting Polymers

DTIC Science & Technology

1991-05-28

doping with nitrosonium fluoborate. 6. Polypyrrole containing luminescent ions has been shown to be useful as in-situ probes of ion transport during...blends, ion transport, fibers, theoretical calculations ABSTRACT (Continue on reverse if necessary and identify by block number) A summary of the research...polymer/dopant ion interactions, symmereically and asymmetrically substituted poly(di-2-heterocycle-2,5-disubstitutedphenylenes), poly(5

Single-ion triblock copolymer electrolytes based on poly(ethylene oxide) and methacrylic sulfonamide blocks for lithium metal batteries

NASA Astrophysics Data System (ADS)

Porcarelli, Luca; Aboudzadeh, M. Ali; Rubatat, Laurent; Nair, Jijeesh R.; Shaplov, Alexander S.; Gerbaldi, Claudio; Mecerreyes, David

2017-10-01

Single-ion conducting polymer electrolytes represent the ideal solution to reduce concentration polarization in lithium metal batteries (LMBs). This paper reports on the synthesis and characterization of single-ion ABA triblock copolymer electrolytes comprising PEO and poly(lithium 1-[3-(methacryloyloxy)propylsulfonyl]-1-(trifluoromethylsulfonyl)imide) blocks, poly(LiMTFSI). Block copolymers are prepared by reversible addition-fragmentation chain transfer polymerization, showing low glass transition temperature (-55 to 7 °C) and degree of crystallinity (51-0%). Comparatively high values of ionic conductivity are obtained (up to ≈ 10-4 S cm-1 at 70 °C), combined with a lithium-ion transference number close to unity (tLi+ ≈ 0.91) and a 4 V electrochemical stability window. In addition to these promising features, solid polymer electrolytes are successfully tested in lithium metal cells at 70 °C providing long lifetime up to 300 cycles, and stable charge/discharge cycling at C/2 (≈100 mAh g-1).

Rocuronium-induced neuromuscular block and sugammadex in pediatric patient with duchenne muscular dystrophy

PubMed Central

Kim, Ji Eun; Chun, Hea Rim

2017-01-01

Abstract Introduction: Anesthetic management of patients with Duchenne muscular dystrophy (DMD) is complicated because these patients are more sensitive to nondepolarizing neuromuscular blocking agents (NMBAs) and are vulnerable to postoperative complications, such as postoperative residual curarization and respiratory failure. Sugammadex is a new reversal agent for aminosteroidal NMBAs, but its safety in children is controversial. Clinical features: An 11-year-old boy with DMD underwent general anesthesia for a percutaneous nephrolithotomy. We used rocuronium bromide and sugammadex to reverse the deep neuromuscular block. Reversal of neuromuscular block was done 15 minutes after administration of 2 mg/kg of sugammadex. The patient's recovery from anesthesia was uneventful, and he was discharged to the postoperative recovery ward. Conclusion: A delayed recovery was achieved, but no adverse events were observed, such as recurarization or hypersensitivity to sugammadex. We report safe use of 2 mg/kg of sugammadex to reverse a deep neuromuscular block in a child with DMD. PMID:28353578

Rocuronium-induced neuromuscular block and sugammadex in pediatric patient with duchenne muscular dystrophy: A case Report.

PubMed

Kim, Ji Eun; Chun, Hea Rim

2017-03-01

Anesthetic management of patients with Duchenne muscular dystrophy (DMD) is complicated because these patients are more sensitive to nondepolarizing neuromuscular blocking agents (NMBAs) and are vulnerable to postoperative complications, such as postoperative residual curarization and respiratory failure. Sugammadex is a new reversal agent for aminosteroidal NMBAs, but its safety in children is controversial. An 11-year-old boy with DMD underwent general anesthesia for a percutaneous nephrolithotomy. We used rocuronium bromide and sugammadex to reverse the deep neuromuscular block. Reversal of neuromuscular block was done 15 minutes after administration of 2 mg/kg of sugammadex. The patient's recovery from anesthesia was uneventful, and he was discharged to the postoperative recovery ward. A delayed recovery was achieved, but no adverse events were observed, such as recurarization or hypersensitivity to sugammadex. We report safe use of 2 mg/kg of sugammadex to reverse a deep neuromuscular block in a child with DMD.

Analgesic efficacy of transversus abdominis plane block in neonates and early infants for colostomy and reversal of colostomy.

PubMed

Chen, Chee Kean; Teo, Shu Ching; Phui, Vui Eng; Saman, Mat Ariffin

2015-01-01

The application of ultrasound-guided transversus abdominis plane (TAP) block in paediatric population is gaining popularity among anaesthetists. We present a case series of ultrasound-guided TAP block in ten neonate and infants undergoing colostomy and reversal of stoma. Classical TAP as described by Hebbard was carried out and a maximum dosage of 1ml/kg of 0.25% levobupivacaine was injected. Pain score was assessed using Neonatal Infant Pain Scale for 24 hours. In all patients, the block was successful with minimal hemodynamic changes intraoperatively and no additional systemic analgesia was needed intraoperative and immediate postoperatively. Ultrasound-guided TAP block has an important role in providing safe and effective analgesia for colostomy creation and reversal of stoma surgeries in paediatric population.

Effects of tetraethylammonium on potassium currents in a molluscan neurons

PubMed Central

1981-01-01

The effects of tetraethylammonium (TEA) on the delayed K+ current and on the Ca2+-activated K+ current of the Aplysia pacemaker neurons R-15 and L-6 were studied. The delayed outward K+ current was measured in Ca2+-free ASW containing tetrodotoxin (TTX), using brief depolarizing clamp pulses. External TEA blocks the delayed K+ current reversibly in a dose-dependent manner. The experimental results are well fitted with a Michaelis-Menten expression, assuming a one-to-one reaction between TEA and a receptor site, with an apparent dissociation constant of 6.0 mM. The block depends on membrane voltage and is reduced at positive membrane potentials. The Ca2+-activated K+ current was measured in Ca2+- free artificial seawater (ASW) containing TTX, using internal Ca2+ ion injection to directly activate the K+ conductance. External TEA and a number of other quaternary ammonium ions block the Ca2+-activated K+ current reversibly in a dose-dependent manner. TEA is the most effective blocker, with an apparent dissociation constant, for a one-to- one reaction with a receptor site, of 0.4 mM. The block decreases with depolarization. The Ca2+-activated K+ current was also measured after intracellular iontophoretic TEA injection. Internal TEA blocks the Ca2+- activated K+ current (but the block is only apparent at positive membrane potentials), is increased by depolarization, and is irreversible. The effects of external and internal TEA can be seen in measurements of the total outward K+ current at different membrane potentials in normal ASW. PMID:6265594

Direct muscarinic and nicotinic receptor-mediated excitation of rat medial vestibular nucleus neurons in vitro

NASA Technical Reports Server (NTRS)

Phelan, K. D.; Gallagher, J. P.

1992-01-01

We have utilized intracellular recording techniques to investigate the cholinoceptivity of rat medial vestibular nucleus (MVN) neurons in a submerged brain slice preparation. Exogenous application of the mixed cholinergic agonists, acetylcholine (ACh) or carbachol (CCh), produced predominantly membrane depolarization, induction of action potential firing, and decreased input resistance. Application of the selective muscarinic receptor agonist muscarine (MUSC), or the selective nicotinic receptor agonists nicotine (NIC) or 1,1-dimethyl-4-phenylpiperazinium (DMPP) also produced membrane depolarizations. The MUSC-induced depolarization was accompanied by decreased conductance, while an increase in conductance appeared to underlie the NIC- and DMPP-induced depolarizations. The muscarinic and nicotinic receptor mediated depolarizations persisted in tetrodotoxin and/or low Ca2+/high Mg2+ containing media, suggesting direct postsynaptic receptor activation. The MUSC-induced depolarization could be reversibly blocked by the selective muscarinic-receptor antagonist, atropine, while the DMPP-induced depolarization could be reversibly suppressed by the selective ganglionic nicotinic-receptor antagonist, mecamylamine. Some neurons exhibited a transient membrane hyperpolarization during the depolarizing response to CCh or MUSC application. This transient inhibition could be reversibly blocked by the gamma-aminobutyric acid (GABA) antagonist, bicuculline, suggesting that the underlying hyperpolarization results indirectly from the endogenous release of GABA acting at GABA receptors. This study confirms the cholinoceptivity of MVN neurons and establishes that individual MVN cells possess muscarinic as well as nicotinic receptors. The data provide support for a prominent role of cholinergic mechanisms in the direct and indirect regulation of the excitability of MVN neurons.

Effects of redox and sulfhydryl reagents on the bioelectric properties of the giant axon of the squid.

PubMed

Huneeus-Cox, F; Fernandez, H L; Smith, B H

1966-09-01

The effects of internally and externally applied sulfhydryl reagents on the bioelectric properties of the giant axon of the squid Loligo pealeii and Dosidicus gigas were studied. Cysteine-HCl (400 mM, pH 7.3) was used to remove axoplasm from the perfusion channel. Oxidizing agents (1 to 60 mM) tended to increase the duration of the action potential and had a slow, irreversible blocking effect when perfused internally; the membrane potential was little affected. Reducing agents applied internally caused a decrease in the spike duration without affecting its height or the membrane potential, although at high concentrations there was reversible deterioration of the action potential. Both external and internal perfusion of mercaptide-forming reagents caused deterioration in the action and membrane potentials with conduction block occurring in 5 to 45 min. 2-mercaptoethanol reversed the effects. Thiol alkylating reagents, iodoacetate and iodoacetamide, were without effect. N-ethylmaleimide did, however, block. Tests with chelating agents for nonheme iron in the membrane brought about no change in the electrical parameters. The implications of the present findings with regard to the macromolecular mechanism of excitation are discussed.

Effects of Redox and Sulfhydryl Reagents on the Bioelectric Properties of the Giant Axon of the Squid

PubMed Central

Huneeus-Cox, F.; Fernandez, H. L.; Smith, B. H.

1966-01-01

The effects of internally and externally applied sulfhydryl reagents on the bioelectric properties of the giant axon of the squid Loligo pealeii and Dosidicus gigas were studied. Cysteine-HCl (400 mM, pH 7.3) was used to remove axoplasm from the perfusion channel. Oxidizing agents (1 to 60 mM) tended to increase the duration of the action potential and had a slow, irreversible blocking effect when perfused internally; the membrane potential was little affected. Reducing agents applied internally caused a decrease in the spike duration without affecting its height or the membrane potential, although at high concentrations there was reversible deterioration of the action potential. Both external and internal perfusion of mercaptide-forming reagents caused deterioration in the action and membrane potentials with conduction block occurring in 5 to 45 min. 2-mercaptoethanol reversed the effects. Thiol alkylating reagents, iodoacetate and iodoacetamide, were without effect. N-ethylmaleimide did, however, block. Tests with chelating agents for nonheme iron in the membrane brought about no change in the electrical parameters. The implications of the present findings with regard to the macromolecular mechanism of excitation are discussed. ImagesFigure 1 PMID:5970570

Hearing and Underwater Noise Exposure

DTIC Science & Technology

1985-08-27

Ordnance Laboratory, White Oak, Silver Springs, Md. Corso, J. F. (1963) Bone-conduction thresholds for sonic and ultrasonic frequencies. J. Acoust...Soc. Am. 35, 1738-1743. Corso, J. F., & Levine, M. (1965a) Sonic and Ultrasonic equal loudness contours. J. Exp. Psychol. 70, 412-416. Corso, J...KEY WORDS (Continue on reverse aide II neceaaary and identity by block number) Hearing, Deafness, Sonar, Noise, Sound, Ultrasound, Infra -sound

Thermophysical Property Testing Using Transient Techniques.

DTIC Science & Technology

1984-06-29

WORDS (Continue on reverse side if necessary and identify by block number) Specific heat HMX carbon/carbon Diffusivity RDX solid propellants Conductivity...energetic materials (AP, " HMX , RDX and HTPB) used in solid rocket fuel to carbon/carbon materials used as rocket nozzles. Studies on AP included single...32 4.1b HMX and RDX ............................35 a 4.2 Carbon/Carbon Materials ...................... 36 5.0 SUMMARY

The Conduct of Quality Basic Combat Individual Training

DTIC Science & Technology

1988-06-03

exminaton of the concepts of child and adult learning . This examination was undertaken to discover the nature of these concepts and thereby to...Nqw York: Academic Press, Inc., 1969. Bruner , Jerome S. The Process of Education. Cambridge: Harvard University Press, 1977. Champagne, David W. and...reverse if necessary and iidentify by block number) FIELD GROUP $S-GEROUP j Individual Training Learning Theory Training Centers Initial Entry Training

Respiratory Toxicology: 1981

DTIC Science & Technology

1981-08-01

AFAMRL-TR-81-81 D /a , 𔄁 RESPIRATORY TOXICOLOGY Annual Technical Report: 1981 P. E. NEWTON, Ph.D. UNIVERSITY OF CALIFORNIA, IRVINE OVERLOOK BRANCH...OF REPORT & PERIOD COVERED RESPIRATORY TOXICOLOGY: 1981 Annual Technical June 1980 through May 198 Ś. PERFORMING ORG. REPORT NUMBER 7. AUTHOR(s) 8...ABSTRACT (Continue on reverse side if necessary and Identify by block number) The Respiratory Toxicology research programs conducted at the Toxic Hazards

A reversible single-molecule switch based on activated antiaromaticity

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

Yin, Xiaodong; Zang, Yaping; Zhu, Liangliang

Single-molecule electronic devices provide researchers with an unprecedented ability to relate novel physical phenomena to molecular chemical structures. Typically, conjugated aromatic molecular backbones are relied upon to create electronic devices, where the aromaticity of the building blocks is used to enhance conductivity. We capitalize on the classical physical organic chemistry concept of Hückel antiaromaticity by demonstrating a single-molecule switch that exhibits low conductance in the neutral state and, upon electrochemical oxidation, reversibly switches to an antiaromatic high-conducting structure. We form single-molecule devices using the scanning tunneling microscope–based break-junction technique and observe an on/off ratio of ~70 for a thiophenylidene derivativemore » that switches to an antiaromatic state with 6-4-6-p electrons. Through supporting nuclear magnetic resonance measurements, we show that the doubly oxidized core has antiaromatic character and we use density functional theory calculations to rationalize the origin of the high-conductance state for the oxidized single-molecule junction. Together, our work demonstrates how the concept of antiaromaticity can be exploited to create single-molecule devices that are highly conducting.« less

A reversible single-molecule switch based on activated antiaromaticity

DOE PAGES

Yin, Xiaodong; Zang, Yaping; Zhu, Liangliang; ...

2017-10-27

Single-molecule electronic devices provide researchers with an unprecedented ability to relate novel physical phenomena to molecular chemical structures. Typically, conjugated aromatic molecular backbones are relied upon to create electronic devices, where the aromaticity of the building blocks is used to enhance conductivity. We capitalize on the classical physical organic chemistry concept of Hückel antiaromaticity by demonstrating a single-molecule switch that exhibits low conductance in the neutral state and, upon electrochemical oxidation, reversibly switches to an antiaromatic high-conducting structure. We form single-molecule devices using the scanning tunneling microscope–based break-junction technique and observe an on/off ratio of ~70 for a thiophenylidene derivativemore » that switches to an antiaromatic state with 6-4-6-p electrons. Through supporting nuclear magnetic resonance measurements, we show that the doubly oxidized core has antiaromatic character and we use density functional theory calculations to rationalize the origin of the high-conductance state for the oxidized single-molecule junction. Together, our work demonstrates how the concept of antiaromaticity can be exploited to create single-molecule devices that are highly conducting.« less

Thermoreversible Morphology and Conductivity of a Conjugated Polymer Network Embedded in Block Copolymer Self-Assemblies

DOE PAGES

Han, Youngkyu; Carrillo, Jan-Michael Y.; Zhang, Zhe; ...

2016-07-19

Self-assembly of block copolymers provides numerous opportunities to create functional materials, utilizing self-assembled microdomains with a variety of morphology and periodic architectures as templates for functional nanofillers. Here new progress is reported toward the fabrication of thermally responsive and electrically conductive polymeric self-assemblies made from a water-soluble poly(thiophene) derivative with short poly(ethylene oxide) side chains and Pluronic L62 block copolymer solution in water. The structural and electrical properties of conjugated polymer-embedded self-assembled architectures are investigated by combining small-angle neutron and X-ray scattering, coarse-grained molecular dynamics simulations, and impedance spectroscopy. The L62 solution template organizes the conjugated polymers by stably incorporatingmore » them into the hydrophilic domains thus inhibiting aggregation. The changing morphology of L62 during the micellarto- lamellar phase transition defines the embedded conjugated polymer network. As a result, the conductivity is strongly coupled to the structural change of the templating L62 phase and exhibits thermally reversible behavior with no signs of quenching of the conductivity at high temperature. In conclusion, this study shows promise for enabling more flexibility in processing and utilizing water-soluble conjugated polymers in aqueous solutions for self-assembly based fabrication of stimuli-responsive nanostructures and sensory materials.« less

Thermoreversible Morphology and Conductivity of a Conjugated Polymer Network Embedded in Block Copolymer Self-Assemblies

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

Han, Youngkyu; Carrillo, Jan-Michael Y.; Zhang, Zhe

Self-assembly of block copolymers provides numerous opportunities to create functional materials, utilizing self-assembled microdomains with a variety of morphology and periodic architectures as templates for functional nanofillers. Here new progress is reported toward the fabrication of thermally responsive and electrically conductive polymeric self-assemblies made from a water-soluble poly(thiophene) derivative with short poly(ethylene oxide) side chains and Pluronic L62 block copolymer solution in water. The structural and electrical properties of conjugated polymer-embedded self-assembled architectures are investigated by combining small-angle neutron and X-ray scattering, coarse-grained molecular dynamics simulations, and impedance spectroscopy. The L62 solution template organizes the conjugated polymers by stably incorporatingmore » them into the hydrophilic domains thus inhibiting aggregation. The changing morphology of L62 during the micellarto- lamellar phase transition defines the embedded conjugated polymer network. As a result, the conductivity is strongly coupled to the structural change of the templating L62 phase and exhibits thermally reversible behavior with no signs of quenching of the conductivity at high temperature. In conclusion, this study shows promise for enabling more flexibility in processing and utilizing water-soluble conjugated polymers in aqueous solutions for self-assembly based fabrication of stimuli-responsive nanostructures and sensory materials.« less

Numerical analysis of the reverse blocking enhancement in High-K passivation AlGaN/GaN Schottky barrier diodes with gated edge termination

NASA Astrophysics Data System (ADS)

Bai, Zhiyuan; Du, Jiangfeng; Xin, Qi; Li, Ruonan; Yu, Qi

2018-02-01

We conducted a numerical analysis on high-K dielectric passivated AlGaN/GaN Schottky barrier diodes (HPG-SBDs) with a gated edge termination (GET). The reverse blocking characteristics were significantly enhanced without the stimulation of any parasitic effect by varying the dielectric thickness dge under the GET, thickness TP, and dielectric constant εr of the high-K passivation layer. The leakage current was reduced by increasing εr and decreasing dge. The breakdown voltage of the device was enhanced by increasing εr and TP. The highest breakdown voltage of 970 V and the lowest leakage current of 0.5 nA/mm were achieved under the conditions of εr = 80, TP = 800 nm, and dge = 10 nm. C-V simulation revealed that the HPG-SBDs induced no parasitic capacitance by comparing the integrated charges of the devices with different high-K dielectrics and different dge.

Measurement and Modeling of Blocking Contacts for Cadmium Telluride Gamma Ray Detectors

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

Beck, Patrick R.

2010-01-07

Gamma ray detectors are important in national security applications, medicine, and astronomy. Semiconductor materials with high density and atomic number, such as Cadmium Telluride (CdTe), offer a small device footprint, but their performance is limited by noise at room temperature; however, improved device design can decrease detector noise by reducing leakage current. This thesis characterizes and models two unique Schottky devices: one with an argon ion sputter etch before Schottky contact deposition and one without. Analysis of current versus voltage characteristics shows that thermionic emission alone does not describe these devices. This analysis points to reverse bias generation current ormore » leakage through an inhomogeneous barrier. Modeling the devices in reverse bias with thermionic field emission and a leaky Schottky barrier yields good agreement with measurements. Also numerical modeling with a finite-element physics-based simulator suggests that reverse bias current is a combination of thermionic emission and generation. This thesis proposes further experiments to determine the correct model for reverse bias conduction. Understanding conduction mechanisms in these devices will help develop more reproducible contacts, reduce leakage current, and ultimately improve detector performance.« less

A calcium-permeable cGMP-activated cation conductance in hippocampal neurons

NASA Technical Reports Server (NTRS)

Leinders-Zufall, T.; Rosenboom, H.; Barnstable, C. J.; Shepherd, G. M.; Zufall, F.

1995-01-01

Whole-cell patch clamp recordings detected a previously unidentified cGMP-activated membrane conductance in cultured rat hippocampal neurons. This conductance is nonselectively permeable for cations and is completely but reversibly blocked by external Cd2+. The Ca2+ permeability of the hippocampal cGMP-activated conductance was examined in detail, indicating that the underlying ion channels display a high relative permeability for Ca2+. The results indicate that hippocampal neurons contain a cGMP-activated membrane conductance that has some properties similar to the cyclic nucleotide-gated channels previously shown in sensory receptor cells and retinal neurons. In hippocampal neurons this conductance similarly could mediate membrane depolarization and Ca2+ fluxes in response to intracellular cGMP elevation.

Control of Biosonar Behavior by the Auditory Cortex

DTIC Science & Technology

1988-11-28

TITLE (include Security Classification) Control of Biosonar Behavior by the Auditory Cortex 12. PERSONAL AUTHOR(S) Nobuo Suga and Stephen Gaioni 13a...NOTATION 17. COSATI CODES IS SUBJECT TERMS (Continue on reverse if necessary and identify by block number) FIELD GROUP1 SUB-GROUP - biosonar ; echolocation...SLesion experiments were conducted to examine whether the functional organization of the mustached bat’s auditory cortex is related to biosonar

Generalship in War: The Principles of Operational Command,

DTIC Science & Technology

1987-05-04

GROUP SUB-GROUP generalship operational art senior leadership command operational command 19. ABSTRACT (Continue on reverse if necessary and identify by...block number) The recent interest in the operational level of war in American military circles has awakened a long dormant appreciation of the art of...war in American military circles has awakened a long dormant appreciation of the art of planning and conducting campaigns. Unfortunately, there has

A comparison between the blocking actions of 2-(4-phenylpiperidino) cyclohexanol (AH 5183) and its N-methyl quaternary analogue (AH 5954)

PubMed Central

Marshall, I. G.

1970-01-01

1. The neuromuscular blocking activities of AH 5183 (2-(4-phenylpiperidino) cyclohexanol) and its N-methyl quaternary analogue (AH 5954) were compared in rapidly stimulated nerve-skeletal muscle preparations of the rat, chicken and cat. 2. The evidence indicated that in isolated preparations the neuromuscular block produced by both AH 5183 and AH 5954 was primarily pre-junctional in origin. That produced by AH 5954 was readily reversible either by washing the tissue or by reducing the stimulation frequency, whereas that produced by AH 5183 was difficult to reverse in these ways. 3. Low doses of AH 5954 sensitized the rat hemidiaphragm preparation to the neuromuscular blocking action of choline. The neuromuscular block produced by choline was reversible by tetraethylammonium but not by neostigmine. This suggested that the blocking action of choline is at least partly pre-junctional in nature. 4. In anaesthetized cats AH 5954 possessed a biphasic neuromuscular blocking action. The initial phase was rapid in onset, suggestive of a post-junctional action, whereas the second phase was prolonged and reversible by choline, suggestive of a prejunctional inhibitory action on the choline transport mechanism. AH 5183 produced no initial blocking action and was irreversible by choline. 5. Both AH 5183 and AH 5954 possessed local anaesthetic and α-adrenoceptor blocking actions. These actions and the neuromuscular blocking action were affected to different degrees by quaternization, suggesting that the three main actions of the two drugs are independent. 6. It was concluded that AH 5954 and AH 5183 act at different pre-junctional sites at the neuromuscular junction, AH 5954 acting extraneuronally by inhibiting choline transport and AH 5183 intraneuronally at the level of the synaptic vesicle membrane. PMID:4395087

Operating room discharge after deep neuromuscular block reversed with sugammadex compared with shallow block reversed with neostigmine: a randomized controlled trial.

PubMed

Putz, Laurie; Dransart, Christophe; Jamart, Jacques; Marotta, Maria-Laura; Delnooz, Geraldine; Dubois, Philippe E

2016-12-01

To determine if reversing a deep or moderate block with sugammadex, compared with a shallow block reversed with neostigmine, reduces the time to operating room discharge after surgery and the time spent in the postanesthesia care unit. A randomized controlled trial. Monocentric study performed from February 2011 until May 2012. One hundred consenting women with American Society of Anesthesiologists grade I or II were randomized into 2 groups. Laparoscopic hysterectomy was performed under desflurane general anesthesia. For the neostigmine (N) group, 0.45 mg · kg -1 rocuronium was followed by spontaneous recovery. A 5-mg rescue bolus was administered only if surgical evaluation was unacceptable. At the end of surgery, 50 μg · kg -1 neostigmine with glycopyrrolate was administered. For the sugammadex (S) group, a higher intubating rocuronium dose (0.6 mg · kg -1 ) was followed by 5-mg boluses each time the train-of-four count exceeded 2. Sugammadex (2-4 mg · kg -1 ) was administered to reverse the block. All patients were extubated after obtaining a train-of-four ratio of 0.9. The duration between the end of surgery and operating room discharge and the time spent in the postanesthesia care unit. The time till operating room discharge was shorter and more predictable in group S (9.15±4.28 minutes vs 13.87±11.43 minutes in group N; P=.005). The maximal duration in group S was 22 minutes, compared with 72 minutes in group N. The time spent in the postanesthesia care unit was not significantly different (group S: 47.75±31.77 minutes and group N: 53.43±40.57 minutes; P=.543). Maintaining a deep neuromuscular block during laparoscopic hysterectomy reversed at the end of the procedure with sugammadex enabled a faster and more predictable time till operating room discharge than did the classical combination of a shallower block reversed with neostigmine. Copyright © 2016 Elsevier Inc. All rights reserved.

Cattaraugus Creek Harbor, New York General Design Memorandum. Phase II (Detailed Design). Volume I. Main Report-GDM II.

DTIC Science & Technology

1976-03-01

of the abetract entered In Block 20, If different from Report) I$. SUPPLEMENTARY NOTES .4 19. KEY WORDS (Continue on reverse aide If neceesary and...Identify by block number) Harbors Cattaraugus Creek Flood Control 20O T’rlq 4CT Caiweut -t reverse se 0 neceeeely mid Identify by block number) The... blocked by the sand bar and lake ice at the creek mouth. During discharges developed by the com- bination of rainfall and snow melt, ice jams raise the

A case series of re-establishment of neuromuscular block with rocuronium after sugammadex reversal.

PubMed

Iwasaki, Hajime; Sasakawa, Tomoki; Takahoko, Kenichi; Takagi, Shunichi; Nakatsuka, Hideki; Suzuki, Takahiro; Iwasaki, Hiroshi

2016-06-01

We report the use of rocuronium to re-establish neuromuscular block after reversal with sugammadex. The aim of this study was to investigate the relationship between the dose of rocuronium needed to re-establish neuromuscular block and the time interval between sugammadex administration and re-administration of rocuronium. Patients who required re-establishment of neuromuscular block within 12 h after the reversal of rocuronium-induced neuromuscular block with sugammadex were included. After inducing general anesthesia and placing the neuromuscular monitor, the protocol to re-establish neuromuscular block was as follows. An initial rocuronium dose of 0.6 mg/kg was followed by additional 0.3 mg/kg doses every 2 min until train-of-four responses were abolished. A total of 11 patients were enrolled in this study. Intervals between sugammadex and second rocuronium were 12-465 min. Total dose of rocuronium needed to re-establish neuromuscular block was 0.6-1.2 mg/kg. 0.6 mg/kg rocuronium re-established neuromuscular block in all patients who received initial sugammadex more than 3 h previously. However, when the interval between sugammadex and second rocuronium was less than 2 h, more than 0.6 mg/kg rocuronium was necessary to re-establish neuromuscular block.

Repair, Evaluation, Maintenance, and Rehabilitation Research Program: Case Histories of Corps Breakwater and Jetty Structures. Report 5. North Atlantic Division

DTIC Science & Technology

1988-11-01

TERMS (Continue on reverse if necessary and identify by block number) FIELD GROUP SUB-GROUP Breakwater REMR (Repair, Evaluation, Concrete armor units...Maintenance, and Rehabilitation) Jetty Rubble-mound structures 19. ABSTRACT (Continue on reverse if necessary and identify by block number) :-This...have been repaired since construction. Other construction materials that have been used include steel, dolosse, concrete cap, concrete block , and

On the Application of Time-Reversed Space-Time Block Code to Aeronautical Telemetry

DTIC Science & Technology

2014-06-01

Keying (SOQPSK), bit error rate (BER), Orthogonal Frequency Division Multiplexing ( OFDM ), Generalized time-reversed space-time block codes (GTR-STBC) 16...Alamouti code [4]) is optimum [2]. Although OFDM is generally applied on a per subcarrier basis in frequency selective fading, it is not a viable...Calderbank, “Finite-length MIMO decision feedback equal- ization for space-time block-coded signals over multipath-fading channels,” IEEE Transac- tions on

Precomplexation and Activation of Carboxylate and Phosphate Esters

DTIC Science & Technology

1992-03-02

SUBJECT TERMS (Continue on reverse if necessary and identify by block number) FIELD GROUP SUB-GROUP 07 03 19 ABSTRACT (Continue on reverse if...necessary and identify by block number) This is the final report for contract N00014-88-K-0309. It summarizes our previously submitted Technical Reports #1

Inclusion Complexes of Diisopropyl Fluorophosphate with Cyclodextrins.

DTIC Science & Technology

1987-09-01

SUPPLEMENTARY NOTATION For Submission to Journal of Catalysis. 17. COSATI CODES 18. SUBJECT TERMS (Continue on reverse if necessary and identify by block...number) FIELD GROUP SUB-GROUP 19. ABSTRACT (Continue on reverse if necessary and identify by block number) See Attached DTIC S ELECTESNOV 2 3 1987D 20

When global rule reversal meets local task switching: The neural mechanisms of coordinated behavioral adaptation to instructed multi-level demand changes.

PubMed

Shi, Yiquan; Wolfensteller, Uta; Schubert, Torsten; Ruge, Hannes

2018-02-01

Cognitive flexibility is essential to cope with changing task demands and often it is necessary to adapt to combined changes in a coordinated manner. The present fMRI study examined how the brain implements such multi-level adaptation processes. Specifically, on a "local," hierarchically lower level, switching between two tasks was required across trials while the rules of each task remained unchanged for blocks of trials. On a "global" level regarding blocks of twelve trials, the task rules could reverse or remain the same. The current task was cued at the start of each trial while the current task rules were instructed before the start of a new block. We found that partly overlapping and partly segregated neural networks play different roles when coping with the combination of global rule reversal and local task switching. The fronto-parietal control network (FPN) supported the encoding of reversed rules at the time of explicit rule instruction. The same regions subsequently supported local task switching processes during actual implementation trials, irrespective of rule reversal condition. By contrast, a cortico-striatal network (CSN) including supplementary motor area and putamen was increasingly engaged across implementation trials and more so for rule reversal than for nonreversal blocks, irrespective of task switching condition. Together, these findings suggest that the brain accomplishes the coordinated adaptation to multi-level demand changes by distributing processing resources either across time (FPN for reversed rule encoding and later for task switching) or across regions (CSN for reversed rule implementation and FPN for concurrent task switching). © 2017 Wiley Periodicals, Inc.

XYFREZ.4 User’s Manual.

DTIC Science & Technology

1987-12-01

F T FILE I MEuSpecial Report 87-26 December 1987 US Army Corps of Engineers Cold Regions Research & Engineering Laboratory XYFREZ.4 User’s manual...Freeze/thaw User’s manual 19. ABSTRACT (Continue on reverse if necessary and identify by block number) - -- Using the program XYFREZ, version 4, one...may simulate two-dimensional conduction of heat, with or without phase change. The mathematical method employed uses finite elements in space and

Effects of Extended Hypoxia on Night Vision

DTIC Science & Technology

1983-06-01

Continue on reverse aide it necessary and identify by block number) hypoxia, anoxia , night vision, dark adaptation, extended hypoxia /y虦 SABDST’RACT M=t...and his colleagues, who not only quantified significant aspects of the dark adaptation function due to anoxia (hypoxia) (12,13,14,16), but also...and his co-workers (7) conducted related and very significant research on bright- ness discrimination, and concluded that anoxia acts mainly on the

Interactive On-Line Conferences.

DTIC Science & Technology

1984-12-01

equipment and greater communication bandwidth than voice, and studies by Chapanis[16] suggest that the - usefulness of video in helping a group solve a...time conferences were conducted using RTCAL, in groups of up to four users at a time. (Because all participants’ "workstations" run on the same time...interfacds. 20 ABSTRACT (Continue on reverse side if neceseery and Identify by block number) 1 A real-time conference allows a group of users, each at his

Production of thermal insulation blocks from bottom ash of fluidized bed combustion system.

PubMed

Mandal, A K; Sinha, O P

2017-08-01

The issues of disposal and environmental problems are increased by the generation of bottom ash from the thermal power plants day by day; hence, its recycling is required. The present study aimed to make thermal insulation blocks using as raw material bottom ash and iron ore slime as a binder and to characterize their engineering properties. Two different fineness values of bottom ash were considered with varying amounts of iron ore slime (0-10%) to make the blocks. Blocks were dried followed by firing at 1000, 1100 and 1200°C, respectively. Cold crushing strength, density and thermal conductivity of these fired blocks showed increasing behaviour with firing temperature, fineness of bottom ash and iron ore slime content. In contrast, a reverse trend was observed in the case of porosity. With increasing firing temperature, the formation of lower melting phases like iron silicate followed by iron aluminium silicate was observed, which imparts the strength inside the blocks. The coarser particles of bottom ash increase the interparticle spaces, which enhances the apparent porosity, resulting in higher thermal insulation property in the blocks. Blocks having better thermal insulation property could be possible to make effectively from coarse bottom ash by adding iron ore slime as a binder.

Novel Designs of Quantum Reversible Counters

NASA Astrophysics Data System (ADS)

Qi, Xuemei; Zhu, Haihong; Chen, Fulong; Zhu, Junru; Zhang, Ziyang

2016-11-01

Reversible logic, as an interesting and important issue, has been widely used in designing combinational and sequential circuits for low-power and high-speed computation. Though a significant number of works have been done on reversible combinational logic, the realization of reversible sequential circuit is still at premature stage. Reversible counter is not only an important part of the sequential circuit but also an essential part of the quantum circuit system. In this paper, we designed two kinds of novel reversible counters. In order to construct counter, the innovative reversible T Flip-flop Gate (TFG), T Flip-flop block (T_FF) and JK flip-flop block (JK_FF) are proposed. Based on the above blocks and some existing reversible gates, the 4-bit binary-coded decimal (BCD) counter and controlled Up/Down synchronous counter are designed. With the help of Verilog hardware description language (Verilog HDL), these counters above have been modeled and confirmed. According to the simulation results, our circuits' logic structures are validated. Compared to the existing ones in terms of quantum cost (QC), delay (DL) and garbage outputs (GBO), it can be concluded that our designs perform better than the others. There is no doubt that they can be used as a kind of important storage components to be applied in future low-power computing systems.

5.8kV SiC PiN Diode for Switching of High-Efficiency Inductive Pulsed Plasma Thruster Circuits

NASA Technical Reports Server (NTRS)

Toftul, Alexandra; Polzin, Kurt A.; Hudgins, Jerry L.

2014-01-01

Inductive Pulsed Plasma Thruster (IPPT) pulse circuits, such as those needed to operate the Pulsed Inductive Thruster (PIT), are required to quickly switch capacitor banks operating at a period of µs while conducting current at levels on the order of at least 10 kA. [1,2] For all iterations of the PIT to date, spark gaps have been used to discharge the capacitor bank through an inductive coil. Recent availability of fast, high-power solid state switching devices makes it possible to consider the use of semiconductor switches in modern IPPTs. In addition, novel pre-ionization schemes have led to a reduction in discharge energy per pulse for electric thrusters of this type, relaxing the switching requirements for these thrusters. [3,4] Solid state switches offer the advantage of greater controllability and reliability, as well as decreased drive circuit dimensions and mass relative to spark gap switches. The use of solid state devices such as Integrated Gate Bipolar Transistors (IGBTs), Gate Turn-off Thyristors (GTOs) and Silicon-Controlled Rectifiers (SCRs) often involves the use of power diodes. These semiconductor devices may be connected antiparallel to the switch for protection from reverse current, or used to reduce power loss in a circuit by clamping off current ringing. In each case, higher circuit efficiency may be achieved by using a diode that is able to transition, or 'switch,' from the forward conducting state ('on' state) to the reverse blocking state ('off' state) in the shortest amount of time, thereby minimizing current ringing and switching losses. Silicon Carbide (SiC) PiN diodes offer significant advantages to conventional fast-switching Silicon (Si) diodes for high power and fast switching applications. A wider band gap results in a breakdown voltage 10 times that of Si, so that a SiC device may have a thinner drift region for a given blocking voltage. [5] This leads to smaller, lighter devices for high voltage applications, as well as reduced forward conduction losses, faster reverse recovery time (faster turn-off), and lower-magnitude reverse recovery current. In addition, SiC devices have lower leakage current as compared to their Si counterparts, and a high thermal conductivity, potentially allowing the former to operate at higher temperatures with a smaller, lighter heatsink (or no heatsink at all).

Aging specifically impairs switching to an allocentric navigational strategy

PubMed Central

Harris, Mathew A.; Wiener, Jan M.; Wolbers, Thomas

2012-01-01

Navigation abilities decline with age, partly due to deficits in numerous component processes. Impaired switching between these various processes (i.e., switching navigational strategies) is also likely to contribute to age-related navigational impairments. We tested young and old participants on a virtual plus maze task (VPM), expecting older participants to exhibit a specific strategy switching deficit, despite unimpaired learning of allocentric (place) and egocentric (response) strategies following reversals within each strategy. Our initial results suggested that older participants performed worse during place trial blocks but not response trial blocks, as well as in trial blocks following a strategy switch but not those following a reversal. However, we then separated trial blocks by both strategy and change type, revealing that these initial results were due to a more specific deficit in switching to the place strategy. Place reversals and switches to response, as well as response reversals, were unaffected. We argue that this specific “switch-to-place” deficit could account for apparent impairments in both navigational strategy switching and allocentric processing and contributes more generally to age-related decline in navigation. PMID:23125833

Aging specifically impairs switching to an allocentric navigational strategy.

PubMed

Harris, Mathew A; Wiener, Jan M; Wolbers, Thomas

2012-01-01

Navigation abilities decline with age, partly due to deficits in numerous component processes. Impaired switching between these various processes (i.e., switching navigational strategies) is also likely to contribute to age-related navigational impairments. We tested young and old participants on a virtual plus maze task (VPM), expecting older participants to exhibit a specific strategy switching deficit, despite unimpaired learning of allocentric (place) and egocentric (response) strategies following reversals within each strategy. Our initial results suggested that older participants performed worse during place trial blocks but not response trial blocks, as well as in trial blocks following a strategy switch but not those following a reversal. However, we then separated trial blocks by both strategy and change type, revealing that these initial results were due to a more specific deficit in switching to the place strategy. Place reversals and switches to response, as well as response reversals, were unaffected. We argue that this specific "switch-to-place" deficit could account for apparent impairments in both navigational strategy switching and allocentric processing and contributes more generally to age-related decline in navigation.

Manifestations of Lyme carditis.

PubMed

Kostić, Tomislav; Momčilović, Stefan; Perišić, Zoran D; Apostolović, Svetlana R; Cvetković, Jovana; Jovanović, Andriana; Barać, Aleksandra; Šalinger-Martinović, Sonja; Tasić-Otašević, Suzana

2017-04-01

The first data of Lyme carditis, a relatively rare manifestation of Lyme disease, were published in eighties of the last century. Clinical manifestations include syncope, light-headedness, fainting, shortness of breath, palpitations, and/or chest pain. Atrioventricular (AV) electrical block of varying severity presents the most common conduction disorder in Lyme carditis. Although is usually mild, AV block can fluctuates rapidly and progress from a prolonged P-R interval to a His-Purkinje block within minutes to hours and days. Rarely, Lyme disease may be the cause of endocarditis, while some studies and reports, based on serological and/or molecular investigations, have suggested possible influence of Borrelia burgdorferi on degenerative cardiac valvular disease. Myocarditis, pericarditis, pancarditis, dilated cardiomyopathy, and heart failure have also been described as possible manifestations of Lyme carditis. The clinical course of Lyme carditis is generally mild, short term, and in most cases, completely reversible after adequate antibiotic treatment. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Mitigation of Shore Damage Attributed to the Federal Navigation Structures at Ludington Harbor, Michigan.

DTIC Science & Technology

1975-12-01

In Block 20, If different from Report) IS. SUPPLEMENTARY NOTES 19. KEY WORDS (Continu, on reverse aide If necesary and Identify by block number) 20...AST’R ACT (Cndbie m reverse ohb N n..e~ww and ideti fy by block number) DD JA 473 EDITION OF I NOV GS 15 OBSOLETE 4~ -i ~SECURITY CLASSIFICATION OF...and Harbor Act of 1867 provided Federal assistance for improving the harbor and channel. Revetments and channel piers were constructed under this Act

An O([Formula: see text]) algorithm for sorting signed genomes by reversals, transpositions, transreversals and block-interchanges.

PubMed

Yu, Shuzhi; Hao, Fanchang; Leong, Hon Wai

2016-02-01

We consider the problem of sorting signed permutations by reversals, transpositions, transreversals, and block-interchanges. The problem arises in the study of species evolution via large-scale genome rearrangement operations. Recently, Hao et al. gave a 2-approximation scheme called genome sorting by bridges (GSB) for solving this problem. Their result extended and unified the results of (i) He and Chen - a 2-approximation algorithm allowing reversals, transpositions, and block-interchanges (by also allowing transversals) and (ii) Hartman and Sharan - a 1.5-approximation algorithm allowing reversals, transpositions, and transversals (by also allowing block-interchanges). The GSB result is based on introduction of three bridge structures in the breakpoint graph, the L-bridge, T-bridge, and X-bridge that models goodreversal, transposition/transreversal, and block-interchange, respectively. However, the paper by Hao et al. focused on proving the 2-approximation GSB scheme and only mention a straightforward [Formula: see text] algorithm. In this paper, we give an [Formula: see text] algorithm for implementing the GSB scheme. The key idea behind our faster GSB algorithm is to represent cycles in the breakpoint graph by their canonical sequences, which greatly simplifies the search for these bridge structures. We also give some comparison results (running time and computed distances) against the original GSB implementation.

The tetravalent organic cation spermine causes the gating of the IRK1 channel expressed in murine fibroblast cells.

PubMed Central

Ishihara, K; Hiraoka, M; Ochi, R

1996-01-01

1. The activation kinetics of the IRK1 channel stably expressed in L cells (a murine fibroblast cell line) were studied under the whole-cell voltage clamp. Without polyamines or Mg2+ in the pipettes, inward currents showed an exponential activation on hyperpolarization. The steep inward rectification of the currents around the reversal potential (Erev) could be described by the open-close transition of the channel with first-order kinetics. 2. When the tetravalent organic cation spermine (Spm) was added in the pipettes, the activation kinetics changed; this was explicable by the increase in the closing rate constant. The activation of the currents observed without Spm or Mg2+ in the pipettes was ascribed to the unblocking of the 'endogenous-Spm block'. 3. In the presence of the divalent cation putrescine (Put) or of Mg2+ in the pipettes, a different non-conductive state suppressed the outward currents on depolarization; the channels instantaneously changed to the open state on repolarization. As the depolarization was prolonged, this non-conductive state was replaced by the non-conductive state that shows an exponential activation on repolarization. This phenomenon was attributed to the redistribution of the channels from the Put- or Mg(2+)-blocked state to the 'endogenous Spm-blocked state' during depolarization. 4. In the presence of the trivalent cation spermidine (Spd) in the pipettes, two different non-conductive states occurred, showing a faster and a slower activation on repolarization. The rectification around Erev was mainly due to the non-conductive state showing a faster activation, which appeared to be the Spd-blocked state. During depolarization, redistribution of the channels to the 'endogenous Spm-blocked state' also occurred. 5. In the presence of Spd, Put or Mg2+ in the pipettes, the voltage dependence of the activation time constant reflecting the unblocking of the 'endogenous Spm' was shifted in the hyperpolarizing direction. 6. Our results suggest that the 'intrinsic gating' that shows the time-dependent activation on repolarization, and that is responsible for the inward rectification around Erev, reflects the blocking kinetics of the tetravalent Spm. PMID:8866861

Comparative effectiveness of Calabadion and sugammadex to reverse non-depolarizing neuromuscular blocking agents

PubMed Central

Haerter, Friederike; Simons, Jeroen Cedric Peter; Foerster, Urs; Duarte, Ingrid Moreno; Diaz-Gil, Daniel; Ganapati, Shweta; Eikermann-Haerter, Katharina; Ayata, Cenk; Zhang, Ben; Blobner, Manfred; Isaacs, Lyle; Eikermann, Matthias

2015-01-01

Background We evaluated the comparative effectiveness of calabadion 2 to reverse non-depolarizing neuromuscular blocking agents (NMBAs) by binding and inactivation. Methods The dose-response relationship of drugs to reverse vecuronium, rocuronium, and cisatracurium-induced neuromuscular block (NMB) was evaluated in vitro (competition binding assays and urine analysis), ex vivo (n=34; phrenic nerve hemidiaphragm preparation) and in vivo (n=108; quadriceps femoris muscle of the rat). Cumulative dose-response curves of calabadions, neostigmine, or sugammadex were created ex vivo at steady-state deep NMB. In living rats, we studied the dose-response relationship of the test drugs to reverse deep block under physiological conditions and we measured the amount of calabadion 2 excreted in the urine. Results In vitro experiments showed that calabadion 2 binds rocuronium with 89 times the affinity of sugammadex (Ka = 3.4 × 109 M−1 and Ka = 3.8 × 107 M−1). Urine analysis (proton nuclear magnetic resonance), competition binding assays and ex vivo study results obtained in the absence of metabolic deactivation are in accordance with an 1:1 binding ratio of sugammadex and calabadion 2 toward rocuronium. In living rats, calabadion 2 dose-dependently and rapidly reversed all NMBAs tested. The molar potency of calabadion 2 to reverse vecuronium and rocuronium was higher compared to sugammadex. Calabadion 2 was eliminated renally, and did not affect blood pressure or heart rate. Conclusion Calabadion 2 reverses NMB-induced by benzylisoquinolines and steroidal NMBAs in rats more effectively, i.e. faster, than sugammadex. Calabadion 2 is eliminated in the urine and well tolerated in rats. PMID:26418697

Introduction of a Current Waveform, Waveshaping Technique to Limit Conduction Loss in High-Frequency DC-DC Converters Suitable for Space Power

DTIC Science & Technology

1990-06-01

resonant Buck converter 19 ABSTRACT (Continue on reverse if necessary and identify by block number) Space power supply manufacturers have tried to...increase power density and construct smaller, highly efficient power supplies by increasing switching frequency. Incorporation of a power MOSFET as a...Michael, Second Reader \\’-. ohn P. Powers , Chairman Department of Electrical Engineering iii ABSTRACT Space power supply manufacturers have tried to

Final Technical Report: Effects of Impurities on Fuel Cell Performance and Durability

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

James G. Goodwin, Jr.; Hector Colon-Mercado; Kitiya Hongsirikarn

2011-11-11

The main objectives of this project were to investigate the effect of a series of potential impurities on fuel cell operation and on the particular components of the fuel cell MEA, to propose (where possible) mechanism(s) by which these impurities affected fuel cell performance, and to suggest strategies for minimizing these impurity effects. The negative effect on Pt/C was to decrease hydrogen surface coverage and hydrogen activation at fuel cell conditions. The negative effect on Nafion components was to decrease proton conductivity, primarily by replacing/reacting with the protons on the Bronsted acid sites of the Nafion. Even though already wellmore » known as fuel cell poisons, the effects of CO and NH3 were studied in great detail early on in the project in order to develop methodology for evaluating poisoning effects in general, to help establish reproducibility of results among a number of laboratories in the U.S. investigating impurity effects, and to help establish lower limit standards for impurities during hydrogen production for fuel cell utilization. New methodologies developed included (1) a means to measure hydrogen surface concentration on the Pt catalyst (HDSAP) before and after exposure to impurities, (2) a way to predict conductivity of a Nafion membranes exposed to impurities using a characteristic acid catalyzed reaction (methanol esterification of acetic acid), and, more importantly, (3) application of the latter technique to predict conductivity on Nafion in the catalyst layer of the MEA. H2-D2 exchange was found to be suitable for predicting hydrogen activation of Pt catalysts. The Nafion (ca. 30 wt%) on the Pt/C catalyst resides primarily on the external surface of the C support where it blocks significant numbers of micropores, but only partially blocks the pore openings of the meso- and macro-pores wherein lie the small Pt particles (crystallites). For this reason, even with 30 wt% Nafion on the Pt/C, few Pt sites are blocked and, hence, are accessible for hydrogen activation. Of the impurities studied, CO, NH3, perchloroethylene (also known as tetrachloroethylene), tetrahydrofuran, diborane, and metal cations had significant negative effects on the components in a fuel cell. While CO has no effect on the Nafion, it significantly poisons the Pt catalyst by adsorbing and blocking hydrogen activation. The effect can be reversed with time once the flow of CO is stopped. NH3 has no effect on the Pt catalyst at fuel cell conditions; it poisons the proton sites on Nafion (by forming NH4+ cations), decreasing drastically the proton conductivity of Nafion. This poisoning can slowly be reversed once the flow of NH3 is stopped. Perchloroethylene has a major effect on fuel cell performance. Since it has little/no effect on Nafion conductivity, its poisoning effect is on the Pt catalyst. However, this effect takes place primarily for the Pt catalyst at the cathode, since the presence of oxygen is very important for this poisoning effect. Tetrahydrofuran was shown not to impact Nafion conductivity; however, it does affect fuel cell performance. Therefore, its primary effect is on the Pt catalyst. The effect of THF on fuel cell performance is reversible. Diborane also can significant affect fuel cell performance. This effect is reversible once diborane is removed from the inlet streams. H2O2 is not an impurity usually present in the hydrogen or oxygen streams to a fuel cell. However, it is generated during fuel cell operation. The presence of Fe cations in the Nafion due to system corrosion and/or arising from MEA production act to catalyze the severe degradation of the Nafion by H2O2. Finally, the presence of metal cation impurities (Na+, Ca 2+, Fe3+) in Nafion from MEA preparation or from corrosion significantly impacts its proton conductivity due to replacement of proton sites. This effect is not reversible. Hydrocarbons, such as ethylene, might be expected to affect Pt or Nafion but do not at a typical fuel cell temperature of 80oC. In the presence of large quantities of hydrogen on the anode side, ethylene is converted to ethane which is very nonreactive. More surprisingly, even more reactive hydrocarbons such as formic acid and acetaldehyde do not appear to react enough with the strong Bronsted acid sites on Nafion at such low temperatures to affect Nafion conductivity properties. These results clearly identify a number of impurities which can have a detrimental impact on fuel cell performance, although some are reversible. Obviously, fuel cells exposed to impurities/poisons which are reversible can recover their original performance capabilities once the impurity flow is stopped. Impurities with irreversible effects should be either minimized in the feed streams, if possible, or new catalytic materials or ion conductors will need to be used to minimize their impact.« less

Ionic mechanisms and receptor properties underlying the responses of molluscan neurones to 5-hydroxytryptamine

PubMed Central

Gerschenfeld, H. M.; Tritsch, Danièle Paupardin

1974-01-01

1. Molluscan neurones have been found to show six different types of response (three excitatory and three inhibitory) to the iontophoretic application of 5-hydroxytryptamine (5-HT). The pharmacological properties of the receptors and the ionic mechanisms associated with these responses have been analysed. 2. Four of the responses to 5-HT (named A, A′, B and C) are consequent upon an increase in membrane conductance whereas the other two (named α and β) are caused by a decrease in membrane conductance. 3. The A-response to 5-HT consists of a `fast' depolarization due to an increase mainly in Na+-conductance; the A′-response is a `slow' depolarization also associated with a Na+-conductance increase. Receptors mediating the A- and A′-depolarizations have different pharmacological properties and may exist side by side on the same neurone. 4. Both the B- and C-responses are inhibitory. The B-response is a `slow' hyperpolarization due to an increase in K+-conductance, the C-response is a fast hyperpolarization associated with an increase in Cl--conductance. 5. The α-response to 5-HT is a depolarization which becomes reduced in amplitude with cell hyperpolarization and reverses at -75 mV; it is caused by a decrease in K+-conductance. The β-response is an hyperpolarization which increases in amplitude with cell hyperpolarization and reverses at -20/-30 mV. It results from a decrease in conductance to both Na+ and K+ ions. 6. The receptors involved in the 5-HT responses associated with a conductance increase may be recognized by the action of specific antagonists: 7-methyltryptamine blocks only the A-receptors, 5-methoxygramine only the B-receptors and neostigmine only the C-receptors. Curare blocks the A- and C-receptors and bufotenine, the A-, A′- and B-receptors. No specific antagonists have yet been found for the 5-HT responses caused by a conductance decrease. 7. The significance of the multiplicity of receptors is discussed. Their functional significance at synapses is analysed in the following paper. PMID:4155767

[Intermittent left bundle branch block - reversal to normal conduction during general anesthesia].

PubMed

Silva, Ana Maria Oliveira Correia da; Silva, Emília Alexandra Gaspar Lima da

Transient changes in intraoperative cardiac conduction are uncommon. Rare cases of the development or remission of complete left bundle branch block under general and locoregional anesthesia associated with myocardial ischemia, hypertension, tachycardia, and drugs have been reported. Complete left bundle branch block is an important clinical manifestation in some chronic hypertensive patients, which may also be a sign of coronary artery disease, aortic valve disease, or underlying cardiomyopathy. Although usually permanent, it can occur intermittently depending on heart rate (when heart rate exceeds a certain critical value). This is a case of complete left bundle branch block recorded in the preoperative period of urgent surgery that reverted to normal intraoperative conduction under general anesthesia after a decrease in heart rate. It resurfaced, intermittently and in a heart-rate-dependent manner, in the early postoperative period, eventually reverting to normal conduction in a sustained manner during semi-intensive unit monitoring. The test to identify markers of cardiac muscle necrosis was negative. Pain due to the emergency surgical condition and in the early postoperative period may have been the cause of the increase in heart rate up to the critical value, causing blockage. Although the development or remission of this blockade under anesthesia is uncommon, the anesthesiologist should be alert to the possibility of its occurrence. It may be benign; however, the correct diagnosis is very important. The electrocardiographic manifestations may mask or be confused with myocardial ischemia, factors that are especially important in a patient under general anesthesia unable to report the characteristic symptoms of ischemia. Copyright © 2016 Sociedade Brasileira de Anestesiologia. Publicado por Elsevier Editora Ltda. All rights reserved.

Reversal of Vecuronium-induced Neuromuscular Blockade with Low-dose Sugammadex at Train-of-four Count of Four: A Randomized Controlled Trial.

PubMed

Asztalos, László; Szabó-Maák, Zoltán; Gajdos, András; Nemes, Réka; Pongrácz, Adrienn; Lengyel, Szabolcs; Fülesdi, Béla; Tassonyi, Edömér

2017-09-01

Rocuronium-induced neuromuscular block that spontaneously recovered to a train-of-four count of four can be reversed with sugammadex 0.5 or 1.0 mg/kg. We investigated whether these doses of sugammadex can also reverse vecuronium at a similar level of block. Sixty-five patients were randomly assigned, and 64 were analyzed in this controlled, superiority study. Participants received general anesthesia with propofol, sevoflurane, fentanyl, and vecuronium. Measurement of neuromuscular function was performed with acceleromyography (TOF-Watch-SX, Organon Teknika B.V., The Netherlands ). Once the block recovered spontaneously to four twitches in response to train-of-four stimulation, patients were randomly assigned to receive sugammadex 0.5, 1.0, or 2.0 mg/kg; neostigmine 0.05 mg/kg; or placebo. Time from study drug injection to normalized train-of-four ratio 0.9 and the incidence of incomplete reversal within 30 min were the primary outcome variables. Secondary outcome was the incidence of reparalysis (normalized train-of-four ratio less than 0.9). Sugammadex, in doses of 1.0 and 2.0 mg/kg, reversed a threshold train-of-four count of four to normalized train-of-four ratio of 0.9 or higher in all patients in 4.4 ± 2.3 min (mean ± SD) and 2.6 ± 1.6 min, respectively. Sugammadex 0.5 mg/kg reversed the block in 6.8 ± 4.1 min in 70% of patients (P < 0.0001 vs. 1.0 and 2.0 mg/kg), whereas neostigmine produced reversal in 11.3 ± 9.7 min in 77% of patients (P > 0.05 vs. sugammadex 0.5 mg/kg). The overall frequency of reparalysis was 18.7%, but this incidence varied from group to group. Sugammadex 1.0 mg/kg, unlike 0.5 mg/kg, properly reversed a threshold train-of-four count of four vecuronium-induced block but did not prevent reparalysis.

Thermo-reversible morphology and conductivity of a conjugated polymer network embedded in polymeric self-assembly

NASA Astrophysics Data System (ADS)

Han, Youngkyu; Carrillo, Jan-Michael Y.; Zhang, Zhe; Li, Yunchao; Hong, Kunlun; Sumpter, Bobby G.; Ohl, Michael; Paranthaman, Mariappan Parans; Smith, Gregory S.; Do, Changwoo

Self-assembly of block copolymers provides opportunities to create nano hybrid materials, utilizing self-assembled micro-domains with a variety of morphology and periodic architectures as templates for functional nano-fillers. Here we report new progress towards the fabrication of a thermally responsive conducting polymer self-assembly made from a water-soluble poly(thiophene) derivative with short PEO side chains and Pluronic L62 solution in water. The structural and electrical properties of conjugated polymer-embedded nanostructures were investigated by combining SANS, SAXS, CGMD simulations, and impedance spectroscopy. The L62 solution template organizes the conjugated polymers by stably incorporating them into the hydrophilic domains thus inhibiting aggregation. The changing morphology of L62 during the micellar-to-lamellar phase transition defines the embedded conjugated polymer network. The conductivity is strongly coupled to the structural change of the templating L62 phase and exhibits thermally reversible behavior with no signs of quenching of the conductivity at high temperature. The research was sponsored by the Scientific User Facilities Division, Office of BES, U.S. DOE and Laboratory Directed Research and Development Program of ORNL, managed by UT-Battelle, LLC.

Test Excavations at 3LA128. An Early Caddo Occupation on the Red River.

DTIC Science & Technology

1982-04-15

aberact entered in Block 20, It different frot Report) IS. SUPPLEMENTARY NOTES It. KEY WORDS (Continue on reverse side It necessary end Identify by... block number) ! l SITNT’ (CCOlMnue as reverse shb N ne"myaj dad identify by block nmbet) t7The Arkansas Acheological Survey tested site 37.A128 under...Purchase Order DACW29-81-M-0165 on the Field Revetment for the New Orleans District Office of the U.S. Army Corps of Engineers to gather data for

Electron-deficient triarylborane block copolymers: synthesis by controlled free radical polymerization and application in the detection of fluoride ions.

PubMed

Cheng, Fei; Bonder, Edward M; Jäkle, Frieder

2013-11-20

Luminescent triarylborane homo and block copolymers with well-defined chain architectures were synthesized via reversible addition-fragmentation chain transfer polymerization of a vinyl-functionalized borane monomer. The Lewis acid properties of the polymers were exploited in the luminescent detection of fluoride ions. A dual-responsive fluoride sensor was developed by taking advantage of the reversible self-assembly of a PNIPAM-based amphiphilic block copolymer. Anion detection in aqueous solution was realized by introducing positively charged pyridinium moieties along the polymer chain.

Pulse power applications of silicon diodes in EML capacitive pulsers

NASA Astrophysics Data System (ADS)

Dethlefsen, Rolf; McNab, Ian; Dobbie, Clyde; Bernhardt, Tom; Puterbaugh, Robert; Levine, Frank; Coradeschi, Tom; Rinaldi, Vito

1993-01-01

Crowbar diodes are used for increasing the energy transfer from capacitive pulse forming networks. They also prevent voltage reversal on the energy storage capacitors. 52 mm diameter diodes with a 5 kV reverse blocking voltage, rated 40 kA were successfully used for the 32 MJ SSG rail gun. An uprated diode with increased current capability and a 15 kV reverse blocking voltage has been developed. Transient thermal analysis has predicted the current ratings for different pulse length. Analysis verification is obtained from destructive testing.

Direct comparison of the impact of head tracking, reverberation, and individualized head-related transfer functions on the spatial perception of a virtual speech source

NASA Technical Reports Server (NTRS)

Begault, D. R.; Wenzel, E. M.; Anderson, M. R.

2001-01-01

A study of sound localization performance was conducted using headphone-delivered virtual speech stimuli, rendered via HRTF-based acoustic auralization software and hardware, and blocked-meatus HRTF measurements. The independent variables were chosen to evaluate commonly held assumptions in the literature regarding improved localization: inclusion of head tracking, individualized HRTFs, and early and diffuse reflections. Significant effects were found for azimuth and elevation error, reversal rates, and externalization.

Space Shuttle Projects

NASA Image and Video Library

2002-08-06

A student tries to insert plastic blocks into the correct holes in a baby's toy. The seemingly trivial task becomes nearly impossible when the prism glasses he is wearing reverse left and right. This is similar to tests used to measure how astronauts adapt to space and then readapt to Earth. The activity was part of the Space Research and You education event held by NASA's Office of Biological and Physical Research on June 25, 2002, in Arlington, VA, to highlight the research that will be conducted on STS-107.

A Triblock Copolymer Design Leads to Robust Hybrid Hydrogels for High-Performance Flexible Supercapacitors.

PubMed

Zhang, Guangzhao; Chen, Yunhua; Deng, Yonghong; Wang, Chaoyang

2017-10-18

We report here an intriguing hybrid conductive hydrogel as electrode for high-performance flexible supercapacitor. The key is using a rationally designed water-soluble ABA triblock copolymer (termed as IAOAI) containing a central poly(ethylene oxide) block (A) and terminal poly(acrylamide) (PAAm) block with aniline moieties randomly incorporated (B), which was synthesized by reversible additional fragment transfer polymerization. The subsequent copolymerization of aniline monomers with the terminated aniline moieties on the IAOAI polymer generates a three-dimensional cross-linking hybrid network. The hybrid hydrogel electrode demonstrates robust mechanical flexibility, remarkable electrochemical capacitance (919 F/g), and cyclic stability (90% capacitance retention after 1000 cycles). Moreover, the flexible supercapacitor based on this hybrid hydrogel electrode presents a large specific capacitance (187 F/g), superior to most reported conductive hydrogel-based supercapacitors. With the demonstrated additional favorable cyclic stability and excellent capacitive and rate performance, this hybrid hydrogel-based supercapacitor holds great promise for flexible energy-storage device.

A study on amphiphilic fluorinated block copolymer in graphite exfoliation using supercritical CO2 for stable graphene dispersion.

PubMed

Kim, Young Hyun; Lee, Hyang Moo; Choi, Sung Wook; Cheong, In Woo

2018-01-15

In this study, poly(2,2,2-trifluoroethyl methacrylate)-block-poly(4-vinylpyridine) (PTFEMA-b-PVP) was synthesized by stepwise reversible addition-fragmentation chain transfer (RAFT) polymerization for the preparation of graphene by the exfoliation of graphite nanoplatelets (GPs) in supercritical CO 2 (SCCO 2 ). Two different block copolymers (low and high molecular weights) were prepared with the same block ratio and used at different concentrations in the SCCO 2 process. The amount of PTFEMA-b-PVP adsorbed on the GPs and the electrical conductivity of the SCCO 2 -treated GP samples were evaluated using thermogravimetric analysis (TGA) and four-point probe method, respectively. All GP samples treated with SCCO 2 were then dispersed in methanol and the dispersion stability was investigated using online turbidity measurements. The concentration and morphology of few-layer graphene stabilized with PTFEMA-b-PVP in the supernatant solution were investigated by gravimetry, scanning electron microscopy, and Raman spectroscopy. Destabilization study of the graphene dispersions revealed that the longer block copolymer exhibited better affinity for graphene, resulting in a higher yield of stable graphene with minimal defects. Copyright © 2017 Elsevier Inc. All rights reserved.

Separation of Poly(styrene-block-t-butyl methacrylate) Copolymers by Various Liquid Chromatography Techniques

PubMed Central

Šmigovec Ljubič, Tina; Pahovnik, David; Žigon, Majda; Žagar, Ema

2012-01-01

The separation of a mixture of three poly(styrene-block-t-butyl methacrylate) copolymers (PS-b-PtBMA), consisting of polystyrene (PS) blocks of similar length and t-butyl methacrylate (PtBMA) blocks of different lengths, was performed using various chromatographic techniques, that is, a gradient liquid chromatography on reversed-phase (C18 and C8) and normal-phase columns, a liquid chromatography under critical conditions for polystyrene as well as a fully automated two-dimensional liquid chromatography that separates block copolymers by chemical composition in the first dimension and by molar mass in the second dimension. The results show that a partial separation of the mixture of PS-b-PtBMA copolymers can be achieved only by gradient liquid chromatography on reversed-phase columns. The coelution of the two block copolymers is ascribed to a much shorter PtBMA block length, compared to the PS block, as well as a small difference in the length of the PtBMA block in two of these copolymers, which was confirmed by SEC-MALS and NMR spectroscopy. PMID:22489207

Block Copolymer-Based Supramolecular Elastomers with High Extensibility and Large Stress Generation Capability

NASA Astrophysics Data System (ADS)

Noro, Atsushi; Hayashi, Mikihiro

We prepared block copolymer-based supramolecular elastomers with high extensibility and large stress generation capability. Reversible addition fragmentation chain transfer polymerizations were conducted under normal pressure and high pressure to synthesize several large molecular weight polystyrene-b-[poly(butyl acrylate)-co-polyacrylamide]-b-polystyrene (S-Ba-S) block copolymers. Tensile tests revealed that the largest S-Ba-S with middle block molecular weight of 3140k achieved a breaking elongation of over 2000% with a maximum tensile stress of 3.6 MPa and a toughness of 28 MJ/m3 while the reference sample without any middle block hydrogen bonds, polystyrene-b-poly(butyl acrylate)-b-polystyrene with almost the same molecular weight, was merely viscous and not self-standing. Hence, incorporation of hydrogen bonds into a long soft middle block was found to be beneficial to attain high extensibility and large stress generation capability probably due to concerted combination of entropic changes and internal potential energy changes originaing from the dissociation of multiple hydrogen bonds by elongation. This work was supported by JSPS KAKENHI Grant Numbers 13J02357, 24685035, 15K13785, and 23655213 for M.H. and A.N. A.N. also expresses his gratitude for Tanaka Rubber Science & Technology Award by Enokagaku-Shinko Foundation, Japan.

Rational synthesis of low-polydispersity block copolymer vesicles in concentrated solution via polymerization-induced self-assembly.

PubMed

Gonzato, Carlo; Semsarilar, Mona; Jones, Elizabeth R; Li, Feng; Krooshof, Gerard J P; Wyman, Paul; Mykhaylyk, Oleksandr O; Tuinier, Remco; Armes, Steven P

2014-08-06

Block copolymer self-assembly is normally conducted via post-polymerization processing at high dilution. In the case of block copolymer vesicles (or "polymersomes"), this approach normally leads to relatively broad size distributions, which is problematic for many potential applications. Herein we report the rational synthesis of low-polydispersity diblock copolymer vesicles in concentrated solution via polymerization-induced self-assembly using reversible addition-fragmentation chain transfer (RAFT) polymerization of benzyl methacrylate. Our strategy utilizes a binary mixture of a relatively long and a relatively short poly(methacrylic acid) stabilizer block, which become preferentially expressed at the outer and inner poly(benzyl methacrylate) membrane surface, respectively. Dynamic light scattering was utilized to construct phase diagrams to identify suitable conditions for the synthesis of relatively small, low-polydispersity vesicles. Small-angle X-ray scattering (SAXS) was used to verify that this binary mixture approach produced vesicles with significantly narrower size distributions compared to conventional vesicles prepared using a single (short) stabilizer block. Calculations performed using self-consistent mean field theory (SCMFT) account for the preferred self-assembled structures of the block copolymer binary mixtures and are in reasonable agreement with experiment. Finally, both SAXS and SCMFT indicate a significant degree of solvent plasticization for the membrane-forming poly(benzyl methacrylate) chains.

Simulant Gas Test Technique Feasibility

DTIC Science & Technology

1990-05-01

DY’NAMICS LABORATORY WRIGHT RESEARCH AND DEVELOPMENT CENTER AIR FORCE SYSTEMS COMMAND WRIGHT-PATTERSON AIR FORCE BASE, OHIO 45433-6553 NOTIr’ When...TERMS (Continue on reverse if necessary and identify by block number) FIELD GROUP SUB-GROUP Hypersonic-test Air -chemistry Non-equilibrium-flow 0g...ABSTRACT (Continue on reverse if necessary and identify by block number) ’[lie Ulcertaillty engendered by non-equilibrium air effects on hypersonic

Synthetic Helizyme Enzymes.

DTIC Science & Technology

1987-08-18

NOTATION 17. COSATI CODES 18. SUBJECT TERMS (Continue on reverse if necessary and identify by block number) FIELD GROUP SUB-GROUP I Synthetic enzymes...chymotrypsin; molecular modeling; 03 peptide synthesis 19. ABSTRACT (Continue on reverse if necessary and identify by block number) The object of this...for AChE. Additionally, synthetic models ofcL- chymotrypsin built using cyclo- dextrins show catalytic activity over a limited pH range.2 Using L

Monoamines stimulate sex reversal in the saddleback wrasse.

PubMed

Larson, Earl T; Norris, David O; Gordon Grau, E; Summers, Cliff H

2003-02-15

Monoamine neurotransmitters (norepinephrine, dopamine, and serotonin) play an important role in reproduction and sexual behavior throughout the vertebrates. They are the first endogenous chemical signals in the regulation of the hypothalamo-pituitary-gonadal (HPG) axis. In teleosts with behavioral sex determination, much is known about behavioral cues that induce sex reversal. The cues are social, processed via the visual system and depend on the ratio of females to males in the population. The mechanisms by which these external behavioral cues are converted to an internal chemical regulatory process are largely unknown. The protogynous Hawaiian saddleback wrasse, Thalassoma duperrey, was used to investigate the biological pathway mediating the conversion of a social cue into neuroendocrine events regulating sex reversal. Because monoamines play an important role in the regulation of the HPG axis, they were selected as likely candidates for such a conversion. To determine if monoamines could affect sex reversal, drugs affecting monoamines were used in an attempt to either induce sex reversal under non-permissive conditions, or prevent sex reversal under permissive conditions. Increasing norepinephrine or blocking dopamine or serotonin lead to sex reversal in experimental animals under non-permissive conditions. Increasing serotonin blocked sex reversal under permissive conditions, while blocking dopamine or norepinephrine retarded the process. The results presented here demonstrate that monoamines contribute significantly to the control sex reversal. Norepinephrine stimulates initiation and completion of gonadal sex of reversal as well as color change perhaps directly via its effects on the HPG axis. Dopamine exercises inhibitory action on the initiation of sex reversal while 5-HT inhibits both initiation and completion of sex reversal. The serotonergic system appears to be an integral part of the pathway mediating the conversion of a social cue into a neuroendocrine event. The complex organization of neurochemical events controlling the psychosocial, physiological, and anatomical events that constitute reversal of sexual identity includes monoamine neurotransmitters. Copyright 2003 Elsevier Science (USA)

Sugammadex as a reversal agent for neuromuscular block: an evidence-based review

PubMed Central

Schaller, Stefan Josef; Fink, Heidrun

2013-01-01

Sugammadex is the first clinical representative of a new class of drugs called selective relaxant binding agents. It has revolutionized the way anesthesiologists think about drug reversal. Sugammadex selectively binds rocuronium or vecuronium, thereby reversing their neuromuscular blocking action. Due to its 1:1 binding of rocuronium or vecuronium, it is able to reverse any depth of neuromuscular block. So far, it has been approved for use in adult patients and for pediatric patients over 2 years. Since its approval in Europe, Japan, and Australia, further insight on its use in special patient populations and specific diseases have become available. Due to its pharmacodynamic profile, sugammadex, in combination with rocuronium, may have the potential to displace succinylcholine as the “gold standard” muscle relaxant for rapid sequence induction. The use of rocuronium or vecuronium, with the potential of reverse of their action with sugammadex, seems to be safe in patients with impaired neuromuscular transmission, ie, neuromuscular diseases, including myasthenia gravis. Data from long-term use of sugammadex is not yet available. Evidence suggesting an economic advantage of using sugammadex and justifying its relatively high cost for an anesthesia-related drug, is missing. PMID:24098155

Responsive Block Copolymer and Gold Nanoparticle Hybrid Nanotubes.

NASA Astrophysics Data System (ADS)

Chang, Sehoon; Singamaneni, Srikanth; Young, Seth; Tsukruk, Vladimir

2009-03-01

We demonstrate the facile fabrication of responsive polymer and metal nanoparticle composite nanotube structures. The nanotubes are comprised of responsive block copolymer, polystyrene-block-poly (2-vinylpyridine) (PS-b-P2VP), and gold nanoparticles. PS-b-P2VP nanotubes were fabricated using porous alumina template and in situ reduction of the gold nanoparticles in P2VP domains. Owing to the pH sensitive nature of P2VP (anionic polymer with a pKa of 3.8), the nanotubes exhibit a dramatic change in topology in response to the changes in the external pH. Furthermore, the gold nanoparticles in the responsive block exhibit a reversible aggregation, causing a reversible change in optical properties such as absorption.

Pharmacokinetics and Pharmacodynamics of Oximes in Unanesthetized Pigs

DTIC Science & Technology

1991-04-01

D-A234 036 U.S. ARMY MEDICAL RESEARCH p INSTITUTE OF CHEMICAL DEFENSE USAMRICD-TR-91-07 PHARMACOKINETICS AND PHARMACODYNAMICS OF OXIMES IN...SUBJECT TERMS (Continue on reverse if necessary and identify by block number) FIELD GROUP SUB-GROUP 2-PAM Cl, ICD 467, MMB-4, Pharmacokinetics ...Cardiovascular 06 15 Pharmacodynamics, Oximes06 15 19. ABSTRACT (Continue on reverse if necessary and identify by block number) The pharmacokinetics and

Tissue Distribution, Excretion, and Hepatic Biotransformation of Microcystin-LR in Mice

DTIC Science & Technology

1990-07-09

TO 900709 43 16. SUPPLEMENTARY NOTATION 17. COSATI CODES 18. SUBJECT TERMS (Continue on reverse if necessary and identify by block number) FIELD...GROUP SUB-GROUP Imicrocystin-LR, pharmacokinetics, biotransformation, protein binding 19, ABSTRACT (Continue on reverse if necessary and identify by block...the column measured with blue dextrin . Fig. 6. Econo-Pac 1ODG desalting column profile of hepatic- cytosolic radiolabel under denaturing conditions

[Membrane mechanisms of effects of antihypoxic agents bemethyl and almide on neurons of Mollusca].

PubMed

Vislobokov, A I; Marysheva, V V; Shabanov, P D

2003-01-01

Membranotropic effects of the antihypoxants bemithyl and almide, structural analogs of thiobenzimidazole, have been studied on the isolated neuronal preparations of Lymaea stagnalis branchycephalic mollusk. Both drugs in a concentration range of 100-1000 microM produced a reversible, dose-dependent nonselective single-phase blocking action upon the ion channels and completely blocked the channels at a concentration of 10 mM. Therefore, bemithyl and almide are active membranotropic compounds capable (in sufficiently high concentrations) of changing the conductivity of slow sodium, calcium, and potassium ion channels in excitable cells. The protective antihypoxant drug reactions on a systemic level of the organism are probably related to the fact that both drugs in small concentrations are capable of hyperpolarizing the cell membrane, activating the ion channel function, and stabilizing the action potential under hypoxia conditions; in greater concentrations, bemithyl and almide are capable of blocking ion currents, thus reducing the excitability of cells and protecting them from overstress.

Reversal of profound and "deep" residual rocuronium-induced neuromuscular blockade by sugammadex: a neurophysiological study.

PubMed

Pavoni, V; Gianesello, L; De Scisciolo, G; Provvedi, E; Horton, D; Barbagli, R; Conti, P; Conti, R; Giunta, F

2012-05-01

Sugammadex is the first of a new class of selective relaxant binding drugs developed for the rapid and complete reversal of neuromuscular blockade (NMB) induced by the aminosteroid neuromuscular blocking drugs rocuronium and vecuronium. Neuromuscular blocking drugs block the transmission from the peripheral nerve to the muscle units, with reduction and disappearance of the evoked electromyographic activity. Usually, neuromuscular monitoring for the investigational reversal drug is performed by calibrated acceleromyography. The efficacy of sugammadex in reversing profound and "deep" residual rocuronium-induced NMB using myogenic motor evoked potentials (mMEPs) monitoring was evaluated. In this prospective trial, 30 consenting patients undergoing propofol-remifentanil anesthesia for spine surgery were enrolled and divided into two groups: Group 1, reversal of profound NMB (sugammadex 16 mg/Kg, 3 minutes after rocuronium 1.2 mg/Kg) and Group 2, reversal of "deep" residual NMB (sugammadex 4 mg/Kg, 15 minutes after rocuronium 0.6 mg/Kg). Myogenic MEPs registrations of upper and lower limbs and the diaphragm were performed, as well as TOF monitoring. After injection of 4 mg/Kg of sugammadex, the means of recovery time of the basal mMEPs amplitudes (diaphragm, and lower limbs and upper limbs) were 124±9.6, 143±163, 151±207 sec, respectively whereas after 16 mg/Kg of sugammadex the times were 109±13.8, 124±0.6, and 135±14.1 sec. Times to TOF ratio 0.9 were 114±75 and 186±105 sec in Group 1 and 2, respectively. No serious adverse effects related to sugammadex and to electrical stimulation were reported. No reoccurrence of neuromuscular block was observed. Neurophysiological monitoring using mMEPs confirmed that sugammadex provided a complete recovery from profound and "deep" residual rocuronium-induced neuromuscular blockade.

Reverse lyotropic liquid crystals from europium nitrate and P123 with enhanced luminescence efficiency.

PubMed

Yi, Sijing; Li, Qintang; Liu, Hongguo; Chen, Xiao

2014-10-02

Fabrication of lyotropic aggregates containing the lanthanide ions is becoming a preferable way to prepare novel functional materials. Here, the lyotropic liquid crystals (LLCs) of reverse hexagonal, reverse bicontinuous cubic, and lamellar phases have been constructed in sequence directly from the mixtures of Eu(NO3)3·6H2O and Pluronic P123 amphiphilc block copolymer with increasing the salt proportion. Their phase types and structural characteristics were analyzed using polarized optical microscopy (POM) and small-angle X-ray scattering (SAXS) measurements. The driving forces of reverse LLC phase formation were investigated using Fourier-transformed infrared spectroscopy (FTIR) and rheological measurements. The hydrated europium salt was found to act not only as a solvent here, but also as the bridge to form hydrogen bonding between coordinated water molecules and PEO blocks, which played a key role in the reverse LLCs formation. Compared to those in aqueous solutions and solid state, the enhanced luminescence quantum yields and prolonged excited state lifetimes were observed in two europium containing reverse mesophases. The luminescence quenching effect of lanthanide ions was efficiently suppressed, probably due to the substitution of coordinated water molecules by oxyethyl groups of P123 and ordered phase structures of LLCs, where the coordinated europium ions were confined and isolated by PEO blocks. The optimum luminescence performance was then found to exist in the reverse hexagonal phase. The obtained results on such lanthanide-induced reverse LLCs should be referable for designing new luminescent soft materials construction to expand their application fields.

How rapidly does the excess risk of lung cancer decline following quitting smoking? A quantitative review using the negative exponential model.

PubMed

Fry, John S; Lee, Peter N; Forey, Barbara A; Coombs, Katharine J

2013-10-01

The excess lung cancer risk from smoking declines with time quit, but the shape of the decline has never been precisely modelled, or meta-analyzed. From a database of studies of at least 100 cases, we extracted 106 blocks of RRs (from 85 studies) comparing current smokers, former smokers (by time quit) and never smokers. Corresponding pseudo-numbers of cases and controls (or at-risk) formed the data for fitting the negative exponential model. We estimated the half-life (H, time in years when the excess risk becomes half that for a continuing smoker) for each block, investigated model fit, and studied heterogeneity in H. We also conducted sensitivity analyses allowing for reverse causation, either ignoring short-term quitters (S1) or considering them smokers (S2). Model fit was poor ignoring reverse causation, but much improved for both sensitivity analyses. Estimates of H were similar for all three analyses. For the best-fitting analysis (S1), H was 9.93 (95% CI 9.31-10.60), but varied by sex (females 7.92, males 10.71), and age (<50years 6.98, 70+years 12.99). Given that reverse causation is taken account of, the model adequately describes the decline in excess risk. However, estimates of H may be biased by factors including misclassification of smoking status. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

The Role of Frontal Cortical and Medial-Temporal Lobe Brain Areas in Learning a Bayesian Prior Belief on Reversals

PubMed Central

Jang, Anthony I.; Costa, Vincent D.; Rudebeck, Peter H.; Chudasama, Yogita; Murray, Elisabeth A.

2015-01-01

Reversal learning has been extensively studied across species as a task that indexes the ability to flexibly make and reverse deterministic stimulus–reward associations. Although various brain lesions have been found to affect performance on this task, the behavioral processes affected by these lesions have not yet been determined. This task includes at least two kinds of learning. First, subjects have to learn and reverse stimulus–reward associations in each block of trials. Second, subjects become more proficient at reversing choice preferences as they experience more reversals. We have developed a Bayesian approach to separately characterize these two learning processes. Reversal of choice behavior within each block is driven by a combination of evidence that a reversal has occurred, and a prior belief in reversals that evolves with experience across blocks. We applied the approach to behavior obtained from 89 macaques, comprising 12 lesion groups and a control group. We found that animals from all of the groups reversed more quickly as they experienced more reversals, and correspondingly they updated their prior beliefs about reversals at the same rate. However, the initial values of the priors that the various groups of animals brought to the task differed significantly, and it was these initial priors that led to the differences in behavior. Thus, by taking a Bayesian approach we find that variability in reversal-learning performance attributable to different neural systems is primarily driven by different prior beliefs about reversals that each group brings to the task. SIGNIFICANCE STATEMENT The ability to use prior knowledge to adapt choice behavior is critical for flexible decision making. Reversal learning is often studied as a form of flexible decision making. However, prior studies have not identified which brain regions are important for the formation and use of prior beliefs to guide choice behavior. Here we develop a Bayesian approach that formally characterizes learning set as a concept, and we show that, in macaque monkeys, the amygdala and medial prefrontal cortex have a role in establishing an initial belief about the stability of the reward environment. PMID:26290251

A guide to the synthesis of block copolymers using reversible-addition fragmentation chain transfer (RAFT) polymerization.

PubMed

Keddie, Daniel J

2014-01-21

The discovery of reversible-deactivation radical polymerization (RDRP) has provided an avenue for the synthesis of a vast array of polymers with a rich variety of functionality and architecture. The preparation of block copolymers has received significant focus in this burgeoning research field, due to their diverse properties and potential in a wide range of research environments. This tutorial review will address the important concepts behind the design and synthesis of block copolymers using reversible addition-fragmentation chain transfer (RAFT) polymerization. RAFT polymerization is arguably the most versatile of the RDRP methods due to its compatibility with a wide range of functional monomers and reaction media along with its relative ease of use. With an ever increasing array of researchers that possess a variety of backgrounds now turning to RDRP, and RAFT in particular, to prepare their required polymeric materials, it is pertinent to discuss the important points which enable the preparation of high purity functional block copolymers with targeted molar mass and narrow molar mass distribution using RAFT polymerization. The key principles of appropriate RAFT agent selection, the order of monomer addition in block synthesis and potential issues with maintaining high end-group fidelity are addressed. Additionally, techniques which allow block copolymers to be accessed using a combination of RAFT polymerization and complementary techniques are touched upon.

Anoxia increases potassium conductance in hippocampal nerve cells.

PubMed

Hansen, A J; Hounsgaard, J; Jahnsen, H

1982-07-01

The effect of anoxia on nerve cell function was studied by intra- and extracellular microelectrode recordings from the CA1 and CA3 region in guinea pig hippocampal slices. Hyperpolarization and concomitant reduction of the nerve cell input resistance was observed early during anoxia. During this period the spontaneous activity first disappeared, then the evoked activity gradually disappeared. The hyperpolarization was followed by depolarization and an absence of a measurable input resistance. All the induced changes were reversed when the slice was reoxygenated. Reversal of the electro-chemical gradient for Cl- across the nerve cell membrane did not affect the course of events during anoxia. Aminopyridines blocked the anoxic hyperpolarization and attenuated the decrease of membrane resistance, but had no effect on the later depolarization. Blockers of synaptic transmission. Mn++, Mg++ and of Na+-channels (TTX) were without effect on the nerve cell changes during anoxia. It is suggested that the reduction of nerve cell excitability in anoxia is primarily due to increased K+-conductance. Thus, the nerve cells are hyperpolarized and the input resistance reduced, causing higher threshold and reduction of synaptic potentials. The mechanism of the K+-conductance activation is unknown at present.

Effects of Pentobarbital on Respiratory Functional Dynamics in Chronically Instrumented Guinea Pigs

DTIC Science & Technology

1991-01-01

inferior cerebellar peduncle; 10, inferior olive; LRN. lateral reticular nu- cleus; NSTTN. nucleus spinal tract of the trigeminal nerve ; STTN, spinal tract...reverse if necessary and identify by block number) FIELD GROUP SUB-GROUP 06 15 sodium pentobarbital; respiration; chronic single unit 06 04 recording...diaphragmatic EMG; guinea pigs 19. ABSTRACT (Continue on reverse if necessary and identify by block number) CHANG. F.-C. T. Effects of pentobarhital

Future United States Role in European Security

DTIC Science & Technology

1992-08-26

MONITORING ORGANIZATION REPORT NUMBER(S) 6a. NAME OF PERFORMING ORGANIZATION 6b. OFFICE SYMBOL 7a. NAME OF MONITORING ORGANIZATION US Army War College (if...necessary and identify by block number) FIELD GROUP SUB- GROUP 19, ABSTRACT (Continue on reverse if necessary and identify by block number) See reverse...concerning these forces: Of course, they used NATO rules of engagement and worked to NATO standards. They had trained together as NATO forces and

Borehole Tilt Measurements at the Charlevoix Observatory, Quebec.

DTIC Science & Technology

1983-01-31

1q. KEY WORDS (Continue on reverse side it necessary end identify by block number) Borehole tiltmeter Earthquakes Tidal, secular and transient tilts 20...ABSTRACT (Continue on reverse side If necessary and Identify by block number) An array of three Bodenseewerk Gbp borehole tiltmeters has been...established to measure tidal, transient and secular tilting of the Earth’s surface in the Charlevoix region of Quebec. Two of the tiltmeters operate at a

The Antimicrobial Effects of Various Nutrient Electrolyte Beverages

DTIC Science & Technology

1986-05-01

SUPPLEMENTARY NOTATION 17. COSATI CODES 18. SUBJECT TERMS (Continue on reverse if n ecessary and identify by block number) FIELD GROUP SUB-GROUP...reverse if necessary and identify by block number) The purpose of this study was to determine if Staphylococcus aureus, Saccharomy ces cerevisiae...sodium benzoate, and malta- dextrin ); inoculated with A. flavus was incubat ed for various time periods at 30°C~ b Cell volumes {mL) were obtained as

Nanopatterned carbon films with engineered morphology by direct carbonization of UV-stabilized block copolymer films.

PubMed

Wang, Yong; Liu, Jinquan; Christiansen, Silke; Kim, Dong Ha; Gösele, Ulrich; Steinhart, Martin

2008-11-01

Nanopatterned thin carbon films were prepared by direct and expeditious carbonization of the block copolymer polystyrene- block-poly(2-vinylpyridine) (PS- b-P2VP) without the necessity of slow heating to the process temperature and of addition of further carbon precursors. Carbonaceous films having an ordered "dots-on-film" surface topology were obtained from reverse micelle monolayers. The regular nanoporous morphology of PS- b-P2VP films obtained by subjecting reverse micelle monolayers to swelling-induced surface reconstruction could likewise be transferred to carbon films thus characterized by ordered nanopit arrays. Stabilization of PS- b-P2VP by UV irradiation and the concurrent carbonization of both blocks were key to the conservation of the film topography. The approach reported here may enable the realization of a broad range of nanoscaled architectures for carbonaceous materials using a block copolymer ideally suited as a template because of the pronounced repulsion between its blocks and its capability to form highly ordered microdomain structures.

Self-recovery reversible image watermarking algorithm

PubMed Central

Sun, He; Gao, Shangbing; Jin, Shenghua

2018-01-01

The integrity of image content is essential, although most watermarking algorithms can achieve image authentication but not automatically repair damaged areas or restore the original image. In this paper, a self-recovery reversible image watermarking algorithm is proposed to recover the tampered areas effectively. First of all, the original image is divided into homogeneous blocks and non-homogeneous blocks through multi-scale decomposition, and the feature information of each block is calculated as the recovery watermark. Then, the original image is divided into 4×4 non-overlapping blocks classified into smooth blocks and texture blocks according to image textures. Finally, the recovery watermark generated by homogeneous blocks and error-correcting codes is embedded into the corresponding smooth block by mapping; watermark information generated by non-homogeneous blocks and error-correcting codes is embedded into the corresponding non-embedded smooth block and the texture block via mapping. The correlation attack is detected by invariant moments when the watermarked image is attacked. To determine whether a sub-block has been tampered with, its feature is calculated and the recovery watermark is extracted from the corresponding block. If the image has been tampered with, it can be recovered. The experimental results show that the proposed algorithm can effectively recover the tampered areas with high accuracy and high quality. The algorithm is characterized by sound visual quality and excellent image restoration. PMID:29920528

14 CFR 33.97 - Thrust reversers.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Thrust reversers. 33.97 Section 33.97 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.97 Thrust reversers. (a) If the...

14 CFR 33.97 - Thrust reversers.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Thrust reversers. 33.97 Section 33.97 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.97 Thrust reversers. (a) If the...

14 CFR 33.97 - Thrust reversers.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Thrust reversers. 33.97 Section 33.97 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.97 Thrust reversers. (a) If the...

14 CFR 33.97 - Thrust reversers.

Code of Federal Regulations, 2012 CFR

2012-01-01

... STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.97 Thrust reversers. (a) If the... this subpart must be run with the reverser installed. In complying with this section, the power control... regimes of control operations are incorporated necessitating scheduling of the power-control lever motion...

14 CFR 33.97 - Thrust reversers.

Code of Federal Regulations, 2010 CFR

2010-01-01

... STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.97 Thrust reversers. (a) If the... this subpart must be run with the reverser installed. In complying with this section, the power control... regimes of control operations are incorporated necessitating scheduling of the power-control lever motion...

Survey of how different groups of veterinarians manage the use of neuromuscular blocking agents in anesthetized dogs.

PubMed

Martin-Flores, Manuel; Sakai, Daniel M; Campoy, Luis; Gleed, Robin D

2018-03-23

To analyze practice habits associated with the use, reversal and monitoring of nondepolarizing neuromuscular blocking agents (NMBAs) in dogs by different groups of veterinarians. Online anonymous survey to veterinarians. Data from 390 answered surveys. A questionnaire was sent to e-mail list servers of the American College of Veterinary Anesthesia and Analgesia (ACVAA-list), Sociedad Española de Anestesia y Analgesia Veterinaria (SEEAV-list), Colégio Brasileiro de Anestesiologia Veterinária (Brazilian College of Veterinary Anesthesiology; CBAV-list) and American College of Veterinary Ophthalmologists (ACVO-list) to elicit information regarding use of NMBAs and reversal agents, monitoring techniques, criteria for redosing, reversing and assessing adequacy of recovery of neuromuscular function. Binomial logistic regression was used to test for association between responses and group of veterinarians in selected questions. Veterinarians of the ACVO-list use NMBAs on a higher fraction of their caseload than other groups (all p < 0.0001). Subjective assessment (observation) of spontaneous movement, including spontaneous breathing, is the most common method for assessing neuromuscular function (43% of pooled responses); 18% of participants always reverse NMBAs, whereas 16% never reverse them. Restoration of neuromuscular function is assessed subjectively by 35% of respondents. Residual neuromuscular block is the most common concern regarding the use of NMBAs for all groups of veterinarians. Side effects of reversal agents (anticholinesterases) were of least concern for all groups. While most veterinarians are concerned about residual neuromuscular block, relatively few steps are implemented to reduce the risks of this complication, such as routine use of quantitative neuromuscular monitoring or routine reversal of NMBAs. These results suggest a limitation in transferring information among groups of veterinarians, or in implementing techniques suggested by scientific research. Copyright © 2018 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.

Student interacts with a visual distorter demonstrator

NASA Technical Reports Server (NTRS)

2002-01-01

A student tries to insert plastic blocks into the correct holes in a baby's toy. The seemingly trivial task becomes nearly impossible when the prism glasses he is wearing reverse left and right. This is similar to tests used to measure how astronauts adapt to space and then readapt to Earth. The activity was part of the Space Research and You education event held by NASA's Office of Biological and Physical Research on June 25, 2002, in Arlington, VA, to highlight the research that will be conducted on STS-107.

Interactions between acetylcholine, 5-hydroxytryptamine, nicotine and morphine on isolated rabbit atria

PubMed Central

Chittal, S. M.; Dadkar, N. K.; Gaitondé, B. B.

1968-01-01

1. The effects of 5-hydroxytryptamine (5-HT) and morphine on the responses to acetylcholine and nicotine of isolated rabbit atria were studied. 2. 5-Hydroxytryptamine (10 μg/ml.) and morphine (20 μg/ml.) blocked the negative chronotropic and inotropic actions of acetylcholine. 3. Nicotine (20 μg/ml.) produced stimulation of the atria, which was blocked by dichlorisoprenaline, morphine, 5-HT, bretylium and hemicholinium. Hemicholinium block was reversed by choline. 4. In reserpinized preparations, nicotine produced inhibition of atria and this action was also blocked by atropine, 5-HT and morphine. Inhibition induced by nicotine was potentiated by physostigmine. 5. 5-Hydroxytryptamine (20 μg/ml.) produced stimulation of atria. This was blocked by bretylium and reduced by hemicholinium. Hemicholinium block was reversed by choline. 6. It is concluded that 5-HT in low concentrations acts as a weak agonist at the cholinoceptive receptors and therefore blocks the action of acetylcholine. Furthermore, nicotine and larger doses of 5-HT have actions on ganglionic structures and liberate acetylcholine, which in turn releases catecholamines. PMID:4386371

Main-chain supramolecular block copolymers.

PubMed

Yang, Si Kyung; Ambade, Ashootosh V; Weck, Marcus

2011-01-01

Block copolymers are key building blocks for a variety of applications ranging from electronic devices to drug delivery. The material properties of block copolymers can be tuned and potentially improved by introducing noncovalent interactions in place of covalent linkages between polymeric blocks resulting in the formation of supramolecular block copolymers. Such materials combine the microphase separation behavior inherent to block copolymers with the responsiveness of supramolecular materials thereby affording dynamic and reversible materials. This tutorial review covers recent advances in main-chain supramolecular block copolymers and describes the design principles, synthetic approaches, advantages, and potential applications.

Block Copolymers and Ionic Liquids: A New Class of Functional Nanocomposites

NASA Astrophysics Data System (ADS)

Lodge, Timothy

2009-03-01

Block copolymers provide a remarkably versatile platform for achieving desired nanostructures by self-assembly, with lengthscales varying from a few nanometers up to several hundred nanometers. Ionic liquids are an emerging class of solvents, with an appealing set of physical attributes. These include negligible vapor pressure, high chemical and thermal stability, tunable solvation properties, high ionic conductivity, and wide electrochemical windows. For various applications it will be necessary to solidify the ionic liquid into particular spatial arrangements, such as membranes or gels, or to partition the ionic liquid in coexisting phases, such as microemulsions and micelles. One example includes formation of spherical, cylindrical, and vesicular micelles by poly(butadiene-b-ethylene oxide) and poly(styrene-b-methylmethacrylate) in the common hydrophobic ionic liquids [BMI][PF6] and [EMI][TFSI]. This work has been extended to the formation of reversible micelle shuttles between ionic liquids and water, whereby entire micelles transfer from one phase to the other, reversibly, depending on temperature and solvent quality. Formation of ion gels has been achieved by self-assembly of poly(styrene-b-ethylene oxide-b-styrene) triblocks in ionic liquids, and by the thermoreversible system poly(N-isopropylacrylamide-b-ethylene oxide-b-N-isopropylacrylamide), using as little as 4% copolymer. Further, these gels have been shown to be remarkably effective as gate dielectrics in organic thin film transistors. The remarkably high capacitance of the ion gels (> 10 μF/cm^2) supports a very high carrier density in an organic semiconductor such as poly(3-hexylthiophene), leading to milliamp currents for low applied voltages. Furthermore, the rapid mobility of the ions enables switching speeds approaching 10 kHz, orders of magnitude higher than achievable with other polymer-based dielectrics such as PEO/LiClO4. Finally, we have shown that ordered nanostructures of block copolymers plus ionic liquids show the characteristic self-assembly properties of strongly-segregated systems. Prospects for anisotropic ionic conductivity are also being explored.

Imidazolium-based Block Copolymers as Solid-State Separators for Alkaline Fuel Cells and Lithium Ion Batteries

NASA Astrophysics Data System (ADS)

Nykaza, Jacob Richard

In this study, polymerized ionic liquid (PIL) diblock copolymers were explored as solid-state polymer separators as an anion exchange membrane (AEM) for alkaline fuel cells AFCs and as a solid polymer electrolyte (SPE) for lithium-ion batteries. Polymerized ionic liquid (PIL) block copolymers are a distinct set of block copolymers that combine the properties of both ionic liquids (e.g., high conductivity, high electrochemical stability) and block copolymers (e.g., self-assembly into various nanostructures), which provides the opportunity to design highly conductive robust solid-state electrolytes that can be tuned for various applications including AFCs and lithium-ion batteries via simple anion exchange. A series of bromide conducting PIL diblock copolymers with an undecyl alkyl side chain between the polymer backbone and the imidazolium moiety were first synthesized at various compositions comprising of a PIL component and a non-ionic component. Synthesis was achieved by post-functionalization from its non-ionic precursor PIL diblock copolymer, which was synthesized via the reverse addition fragmentation chain transfer (RAFT) technique. This PIL diblock copolymer with long alkyl side chains resulted in flexible, transparent films with high mechanical strength and high bromide ion conductivity. The conductivity of the PIL diblock copolymer was three times higher than its analogous PIL homopolymer and an order of magnitude higher than a similar PIL diblock copolymer with shorter alkyl side chain length, which was due to the microphase separated morphology, more specifically, water/ion clusters within the PIL microdomains in the hydrated state. Due to the high conductivity and mechanical robustness of this novel PIL block copolymer, its application as both the ionomer and AEM in an AFC was investigated via anion exchange to hydroxide (OH-), where a maximum power density of 29.3 mW cm-1 (60 °C with H2/O2 at 25 psig (172 kPa) backpressure) was achieved. Rotating disk electrode (RDE) experiments determined the interfacial resistance imposed during cell assembly between the AEM, catalyst, and ionomer was a factor in fuel cell performance. Further RDE studies investigated the electrochemical stability of the PIL block copolymer ionomer under applied potentials, where it was determined that potential cycling increased the degradation compared to constant voltage or open circuit voltage studies. The PIL diblock copolymer was then anion exchanged to the bis(trifluoromethane)sulfonamide (TFSI-) anion form and imbibed with a lithium salt and ionic liquid solution for use as a SPE in lithium-ion batteries resulting in a maximum discharge capacity of 112 mAh g-1 at 0.1 C with a Coulombic efficiency greater than 94% over 100 cycles. PIL block copolymers have promising mechanical properties and transport properties (i.e., ion conductivity) in both the hydrated (hydrophilic anions; Br-, OH-) and dry (hydrophobic anions; TFSI-) states resulting in highly conductive, chemically/thermally stable, and mechanically robust solid-state polymer separators for use as AEMs in AFCs and as SPEs in lithium-ion batteries.

Supplemental Cultural Resources Investigations and Site Testing for the Pointe Coupee to Arbroth Levee Enlargement and Seepage Control Project, West Baton Rouge Parish, Louisiana

DTIC Science & Technology

1993-07-01

July 316 16. SUPPLEMENTARY NOTATION 17. COSATI CODES 18. SUBJECT TERMS (Continue on reverse if necessary and identify by block number) Bayou Plantation...Archeology Tenements Yatton Plantation 19. ABSTRACT (Continue on reverse if necessary and identify by block number) This report presents the results of Phase 1... Revetment Projects, M-270.2 to 246.0-R ........................................................... 21 Previously Recorded Archeological Sites in the

A functionalizable reverse thermal gel based on a polyurethane/PEG block copolymer

PubMed Central

Park, Daewon; Wu, Wei; Wang, Yadong

2010-01-01

Injectable reverse thermal gels have great potentials as biomaterials for tissue engineering and drug delivery. However, most existing gels lack functional groups that can be modified with biomolecules that can guide cell/material interactions. We created an amine-functionalized ABA block copolymer, poly(ethylene glycol)-poly(serinol hexamethylene urethane), or ESHU. This reverse thermal gel consists of a hydrophobic block (B): poly(serinol hexamethylene urethane) and a hydrophilic block (A): poly(ethylene glycol). The polymer was characterized by GPC, FTIR and 1H FTNMR. Rheological study demonstrated that ESHU solution in phosphate-buffered saline initiated phase transition at 32°C and reached maximum elastic modulus at 37°C. The in vitro degradation tests performed in PBS and cholesterol esterase solutions revealed that the polymer was hydrolyzable and the presence of cholesterol esterase greatly accelerated the hydrolysis. The in vitro cytotoxicity tests carried out using baboon smooth muscle cells demonstrated that ESHU had good cytocompatibility with cell viability indistinguishable from tissue culture treated polystyrene. Subcutaneous implantation in rats revealed well tolerated accurate inflammatory response with moderate ED-1 positive macrophages in the early stages, which largely resolved 4 weeks post-implantation. We functionalized ESHU with a hexapeptide, Ile-Lys-Val-Ala-Val-Ser (IKVAVS), which gelled rapidly at body temperature. We expect this new platform of functionalizable reverse thermal gels to provide versatile biomaterials in tissue engineering and regenerative medicine. PMID:20937526

Short infrared laser pulses block action potentials in neurons

NASA Astrophysics Data System (ADS)

Walsh, Alex J.; Tolstykh, Gleb P.; Martens, Stacey L.; Ibey, Bennett L.; Beier, Hope T.

2017-02-01

Short infrared laser pulses have many physiological effects on cells including the ability to stimulate action potentials in neurons. Here we show that short infrared laser pulses can also reversibly block action potentials. Primary rat hippocampal neurons were transfected with the Optopatch2 plasmid, which contains both a blue-light activated channel rhodopsin (CheRiff) and a red-light fluorescent membrane voltage reporter (QuasAr2). This optogenetic platform allows robust stimulation and recording of action potential activity in neurons in a non-contact, low noise manner. For all experiments, QuasAr2 was imaged continuously on a wide-field fluorescent microscope using a Krypton laser (647 nm) as the excitation source and an EMCCD camera operating at 1000 Hz to collect emitted fluorescence. A co-aligned Argon laser (488 nm, 5 ms at 10Hz) provided activation light for CheRiff. A 200 mm fiber delivered infrared light locally to the target neuron. Reversible action potential block in neurons was observed following a short infrared laser pulse (0.26-0.96 J/cm2; 1.37-5.01 ms; 1869 nm), with the block persisting for more than 1 s with exposures greater than 0.69 J/cm2. Action potential block was sustained for 30 s with the short infrared laser pulsed at 1-7 Hz. Full recovery of neuronal activity was observed 5-30s post-infrared exposure. These results indicate that optogenetics provides a robust platform for the study of action potential block and that short infrared laser pulses can be used for non-contact, reversible action potential block.

Fatigue Life Estimation under Cumulative Cyclic Loading Conditions

NASA Technical Reports Server (NTRS)

Kalluri, Sreeramesh; McGaw, Michael A; Halford, Gary R.

1999-01-01

The cumulative fatigue behavior of a cobalt-base superalloy, Haynes 188 was investigated at 760 C in air. Initially strain-controlled tests were conducted on solid cylindrical gauge section specimens of Haynes 188 under fully-reversed, tensile and compressive mean strain-controlled fatigue tests. Fatigue data from these tests were used to establish the baseline fatigue behavior of the alloy with 1) a total strain range type fatigue life relation and 2) the Smith-Wastson-Topper (SWT) parameter. Subsequently, two load-level multi-block fatigue tests were conducted on similar specimens of Haynes 188 at the same temperature. Fatigue lives of the multi-block tests were estimated with 1) the Linear Damage Rule (LDR) and 2) the nonlinear Damage Curve Approach (DCA) both with and without the consideration of mean stresses generated during the cumulative fatigue tests. Fatigue life predictions by the nonlinear DCA were much closer to the experimentally observed lives than those obtained by the LDR. In the presence of mean stresses, the SWT parameter estimated the fatigue lives more accurately under tensile conditions than under compressive conditions.

Properties of Single K+ and Cl− Channels in Asclepias tuberosa Protoplasts 1

PubMed Central

Schauf, Charles L.; Wilson, Kathryn J.

1987-01-01

Potassium and chloride channels were characterized in Asclepias tuberosa suspension cell derived protoplasts by patch voltage-clamp. Whole-cell currents and single channels in excised patches had linear instantaneous current-voltage relations, reversing at the Nernst potentials for K+ and Cl−, respectively. Whole cell K+ currents activated exponentially during step depolarizations, while voltage-dependent Cl− channels were activated by hyperpolarizations. Single K+ channel conductance was 40 ± 5 pS with a mean open time of 4.5 milliseconds at 100 millivolts. Potassium channels were blocked by Cs+ and tetraethylammonium, but were insensitive to 4-aminopyridine. Chloride channels had a single-channel conductance of 100 ± 17 picosiemens, mean open time of 8.8 milliseconds, and were blocked by Zn2+ and ethacrynic acid. Whole-cell Cl− currents were inhibited by abscisic acid, and were unaffected by indole-3-acetic acid and 2,4-dichlorophenoxyacetic acid. Since internal and external composition can be controlled, patch-clamped protoplasts are ideal systems for studying the role of ion channels in plant physiology and development. Images Fig. 5 PMID:16665712

Quaternary tectonic setting of South-Central coastal California

USGS Publications Warehouse

Lettis, William R.; Hanson, Kathryn L.; Unruh, Jeffrey R.; McLaren, Marcia; Savage, William U.; Keller, Margaret A.

2004-01-01

Recent geodetic, geologic, and seismologic studies show that the south-central coast of California is a region of active Quaternary deformation. Northeast-directed crustal shortening is occurring in a triangular-shaped region between the Hosgri-San Simeon fault system on the west, the Southern Coast Ranges on the northeast, and the western Transverse Ranges on the south. We informally call this region the Los Osos domain. In this study, we conducted detailed geological, seismological, and geophysical investigations to characterize the nature and rates of deformation in the domain. Locations of active and potentially active faults and folds are compiled at a scale of 1:250,000 for the entire domain based primarily on onshore geologic data and offshore geophysical data. Crustal shortening in the domain is accommodated by a series of prominent northwest-trending reverse faults and localized folding. The reverse faults separate distinct structural blocks that have little or no internal deformation. Hangingwall blocks are being uplifted at rates of up to 0.2 mm/yr. Footwall blocks are either static or slowly subsiding at rates of 0.1 mm/yr or less, except for localized areas of concentrated subsidence directly adjacent to some faults. The cumulative rate of crustal shortening is about 1 to 2 mm/yr across the northern part of the domain based on observed geologic deformation. Cumulative shortening across the central and southern parts of the domain is poorly constrained by geologic data and may approach 2 to 3 mm/yr. Historical and instrumental seismicity generally are spatially associated with the uplifted blocks and bordering reverse faults to depths of about 10 km. Together with near-surface geological data and deeper crustal geophysical imaging that show high-angle faulting, the seismicity data indicate that the reverse faults probably extend to the base of the seismogenic crust. The base of the seismogenic crust may correspond with a mid-crustal detachment or decollement surface into which the reverse faults root. We speculate that the detachment may coincide, in part, with the top of a northeast-dipping slab of oceanic crust that extends beneath the western margin of the continent or with the brittle-ductile transition above the subducted slab. The Los Osos domain of north-northeast/south-southwest crustal shortening is structurally detached from the offshore Hosgri Fault Zones. Both the pattern and regional extent of deformation in the Los Osos domain contrast sharply with that of the offshore Santa Maria Basin. The basin is undergoing minor east-northeast/west-southwest crustal shortening at rates of less than 0.1 mm/yr and is moving northwestward at a rate of about 1 to 3 mm/yr relative to the Los Osos domain along the San Simeon and Hosgri Fault Zones. Geodetic data and the kinematics of north-northeast-directed crustal shortening of the Los Osos domain east of the Hosgri Fault Zone show that the rate and cumulative amount of right-slip along the Hosgri Fault Zone progressively decrease southward. Quaternary deformation within the Los Osos domain is related to distributed dextral simple shear associated with Pacific-North American plate motion. Paleomagnetic data show that clockwise rotation of the western Transverse Ranges has occurred along the southern boundary of the domain during the past 6 m.y. During this time, the Salinian crustal block, which forms the eastern boundary of the Los Osos domain, has remained relatively stable. Internal shortening of the Los Osos domain has accommodated the relative motions of these bordering crustal blocks, particularly the rotation of the western Transverse Ranges.

Efficacy and safety of sugammadex in the reversal of deep neuromuscular blockade induced by rocuronium in patients with end-stage renal disease: A comparative prospective clinical trial.

PubMed

de Souza, Camila M; Tardelli, Maria A; Tedesco, Helio; Garcia, Natalia N; Caparros, Mario P; Alvarez-Gomez, Jose A; de Oliveira Junior, Itamar S

2015-10-01

Renal failure affects the pharmacology of nondepolarizing neuromuscular blockers making recovery of neuromuscular function unpredictable. Sugammadex antagonises rocuronium-induced neuromuscular blockade by encapsulating rocuronium, creating a stable complex molecule that is mainly excreted by the kidneys. Previous studies suggest that sugammadex is effective in reversing moderate neuromuscular block in the presence of renal failure, but no data are available regarding reversal of profound neuromuscular block in patients with renal failure. The objective of this study is to compare the efficacy and safety of sugammadex in reversing profound neuromuscular block induced by rocuronium in patients with end-stage renal disease and those with normal renal function. A prospective clinical trial. Two university hospitals, from 1 October 2011 to 31 January 2012. Forty patients undergoing kidney transplant: 20 with renal failure [creatinine clearance (ClCr) <30 ml min] and 20 control patients (ClCr >90 ml min). Neuromuscular monitoring was performed by acceleromyography and train-of-four (TOF) stimulation. Profound neuromuscular block (posttetanic count, one to three responses) was maintained during surgery. Sugammadex 4 mg kg was administered on completion of skin closure. Recovery of the TOF ratio to 0.9 was recorded. Monitoring of neuromuscular function continued in the postanesthesia care unit for a further 2 h. The efficacy of sugammadex was evaluated by the time taken for the TOF ratio to recover to 0.9. The safety of sugammadex was assessed by monitoring for recurrence of neuromuscular block every 15 min for 2 h. Secondary variables were time to recovery of TOF ratio to 0.7 and 0.8. After sugammadex administration, the mean time for recovery of the TOF ratio to 0.9 was prolonged in the renal failure group (5.6 ± 3.6 min) compared with the control group (2.7 ± 1.3 min, P = 0.003). No adverse events or evidence of recurrence of neuromuscular block were observed. In patients with renal failure, sugammadex (4 mg kg) effectively and safely reversed profound rocuronium induced neuromuscular block, but the recovery was slower than healthy patients. Clinicaltrials.gov identifier NCT01785758.

A discrete event simulation model of clinical and operating room efficiency outcomes of sugammadex versus neostigmine for neuromuscular block reversal in Canada.

PubMed

Insinga, Ralph P; Joyal, Cédric; Goyette, Alexandra; Galarneau, André

2016-11-16

The objective of this analysis is to explore potential impact on operating room (OR) efficiency and incidence of residual neuromuscular blockade (RNMB) with use of sugammadex (Bridion™, Merck & Co., Inc., Kenilworth, NJ USA) versus neostigmine for neuromuscular block reversal in Canada. A discrete event simulation (DES) model was developed to compare ORs using either neostigmine or sugammadex for NMB reversal over one month. Selected inputs included OR procedure and turnover times, hospital policies for paid staff overtime and procedural cancellations due to OR time over-run, and reductions in RNMB and associated complications with sugammadex use. Trials show sugammadex's impact on OR time and RNMB varies by whether full neuromuscular recovery (train-of-four ratio ≥0.9) is verified prior to extubation in the OR. Scenarios were therefore evaluated reflecting varied assumptions for neuromuscular reversal practices. With use of moderate neuromuscular block, when full neuromuscular recovery is verified prior to extubation (93 procedures performed with sugammadex, 91 with neostigmine), use of sugammadex versus neostigmine avoided 2.4 procedural cancellations due to OR time over-run and 33.5 h of paid staff overtime, while saving an average of 62 min per OR day. No difference was observed between comparators for these endpoints in the scenario when full neuromuscular recovery was not verified prior to extubation, however, per procedure risk of RNMB at extubation was reduced from 60% to 4% (reflecting 51 cases prevented), with associated reductions in risks of hypoxemia (12 cases avoided) and upper airway obstruction (23 cases avoided). Sugammadex impact in reversing deep neuromuscular block was evaluated in an exploratory analysis. When it was hypothetically assumed that 30 min of OR time were saved per procedure, the number of paid hours of staff over-time dropped from 84.1 to 32.0, with a 93% reduction in the per patient risk of residual blockade. In clinical practice within Canada, for the majority of patients currently managed with moderate neuromuscular block, the principal impact of substituting sugammadex for neostigmine is likely to be a reduction in the risk of residual blockade and associated complications. For patients maintained at a deep level of block to the end of the procedure, sugammadex is likely to both enhance OR efficiency and reduce residual block complications.

Electrochemically Induced Insulator-Metal-Insulator Transformations of Vanadium Dioxide Nanocrystal Films

NASA Astrophysics Data System (ADS)

Milliron, Delia; Dahlman, Clayton; Leblanc, Gabriel; Bergerud, Amy

Vanadium dioxide (VO2) undergoes significant optical, electronic, and structural changes as it transforms between the low-temperature monoclinic and high-temperature rutile phases. The low-temperature state is insulating and transparent, while the high-temperature state is metallic and IR blocking. Alternative stimuli have been utilized to trigger insulator-to-metal transformations in VO2, including electrochemical gating. Here, VO2 nanocrystal films have been prepared by solution deposition of V2O3 nanocrystals followed by oxidative annealing. Nanocrystalline VO2 films are electrochemically reduced, inducing changes in their electronic and optical properties. We observe a reversible transition between infrared transparent insulating phases and a darkened metallic phase by in situ visible-near-infrared spectroelectrochemistry and correlate these observations with structural and electronic changes monitored by X-ray absorption spectroscopy, X-ray diffraction, Raman spectroscopy, and conductivity measurements. Reduction causes an initial transformation to a metallic, IR-colored distorted monoclinic phase. However, an unexpected reversible transition from conductive, reduced monoclinic VO2 to an infrared-transparent insulating phase is observed upon further reduction.

Two modes of polyamine block regulating the cardiac inward rectifier K+ current IK1 as revealed by a study of the Kir2.1 channel expressed in a human cell line.

PubMed

Ishihara, Keiko; Ehara, Tsuguhisa

2004-04-01

The strong inward rectifier K(+) current, I(K1), shows significant outward current amplitude in the voltage range near the reversal potential and thereby causes rapid repolarization at the final phase of cardiac action potentials. However, the mechanism that generates the outward I(K1) is not well understood. We recorded currents from the inside-out patches of HEK 293T cells that express the strong inward rectifier K(+) channel Kir2.1 and studied the blockage of the currents caused by cytoplasmic polyamines, namely, spermine and spermidine. The outward current-voltage (I-V) relationships of Kir2.1, obtained with 5-10 microm spermine or 10-100 microm spermidine, were similar to the steady-state outward I-V relationship of I(K1), showing a peak at a level that is approximately 20 mV more positive than the reversal potential, with a negative slope at more positive voltages. The relationships exhibited a plateau or a double-hump shape with 1 microm spermine/spermidine or 0.1 microm spermine, respectively. In the chord conductance-voltage relationships, there were extra conductances in the positive voltage range, which could not be described by the Boltzmann relations fitting the major part of the relationships. The extra conductances, which generated most of the outward currents in the presence of 5-10 microm spermine or 10-100 microm spermidine, were quantitatively explained by a model that considered two populations of Kir2.1 channels, which were blocked by polyamines in either a high-affinity mode (Mode 1 channel) or a low-affinity mode (Mode 2 channel). Analysis of the inward tail currents following test pulses indicated that the relief from the spermine block of Kir2.1 consisted of an exponential component and a virtually instantaneous component. The fractions of the two components nearly agreed with the fractions of the blockages in Mode 1 and Mode 2 calculated by the model. The estimated proportion of Mode 1 channels to total channels was 0.9 with 0.1-10 microm spermine, 0.75 with 1-100 microm spermidine, and between 0.75 and 0.9 when spermine and spermidine coexisted. An interaction of spermine/spermidine with the channel at an intracellular site appeared to modify the equilibrium of the two conformational channel states that allow different modes of blockage. Our results suggest that the outward I(K1) is primarily generated by channels with lower affinities for polyamines. Polyamines may regulate the amplitude of the outward I(K1), not only by blocking the channels but also by modifying the proportion of channels that show different sensitivities to the polyamine block.

Laser iridotomy to treat uveitis-glaucoma-hyphema syndrome secondary to reverse pupillary block in sulcus-placed intraocular lenses: Case series.

PubMed

Singh, Harmanjit; Modabber, Milad; Safran, Steven G; Ahmed, Iqbal Ike K

2015-10-01

To present cases of uveitis-glaucoma-hyphema (UGH) syndrome due to reverse pupillary block in sulcus-placed posterior chamber intraocular lenses (PC IOLs) that were managed with laser peripheral iridotomy (LPI). Community-based subspecialty clinics. Retrospective interventional case series. A chart review of patients with a sulcus-placed PC IOLs presenting with UGH syndrome and reverse pupillary block with posterior iris bowing as diagnosed by gonioscopy and anterior segment optical coherence tomography was carried out. Laser peripheral iridotomy was performed in the eyes included in the study. The main outcome measure was clinical resolution of UGH syndrome. The study included 6 eyes of 6 patients with a mean age of 59.8 years (range 43.0 to 66.0 years) who presented with unilateral UGH syndrome a mean of 28.7 months (range 0.3 to 84.0 months) after PC IOL implantation. All patients were previously myopic, with 5 (83.3%) having a history of vitrectomy. The mean axial length was 27.0 mm ± 1.4 (SD). An LPI was used to treat the reverse pupillary block with resultant improvement in iris profile and resolution of UGH syndrome in all eyes. The mean intraocular pressure decreased from 30.5 ± 10.0 mm Hg on 0.5 ± 0.8 glaucoma medications to 15.5 ± 3.2 mm Hg postoperatively on 0.7 ± 1.2 medications. The UGH syndrome due to reverse pupillary block occurred after sulcus-placed PC IOLs in susceptible patients, those with axial myopia, and post-vitrectomized eyes. The cases were managed with LPIs. Dr. Ahmed is a consultant to Alcon Laboratories, Inc. and Abbott Medical Optics, Inc. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Sympathetic block by metal clips may be a reversible operation.

PubMed

Thomsen, Lars L; Mikkelsen, Rasmus T; Derejko, Miroslawa; Schrøder, Henrik D; Licht, Peter B

2014-12-01

Thoracoscopic sympathectomy is now used routinely to treat patients with disabling primary hyperhidrosis or facial blushing. Published results are excellent, but side effects, such as compensatory sweating, are also very frequent. The surgical techniques used and the levels of targeting the sympathetic chain vary tremendously. Most surgeons transect or resect the sympathetic chain, but application of a metal clip that blocks transmission of nerve impulses in the sympathetic chain is used increasingly worldwide. This approach offers potential reversibility if patients regret surgery, but the question of reversibility remains controversial. Two recent experimental studies found severe histological signs of nerve damage 4-6 weeks after clip removal, but they only used conventional histopathological staining methods. Thoracoscopic clipping of the sympathetic trunk was performed in adult sheep, and the clip was removed thoracoscopically after 7 days. Following another 4 weeks (n = 6) or 12 weeks (n = 3), the sympathetic trunks were harvested and analysed by conventional and specific nerve tissue immunohistochemical stains (S100, neurofilament protein and synaptophysin). The contralateral sympathetic chains were used as controls. Conventional and immunohistochemical stains demonstrated severe signs of neural damage on the operated side 4 weeks after clip removal. After 12 weeks, these changes had decreased markedly and conventional histology had almost normalized. Conventional and immunohistochemical stains confirmed that application of metal clips to the sympathetic chain caused severe histological damage in the sympathetic trunk that remained visible 4 weeks after clip removal. However, after 12 weeks, these signs of damage had clearly decreased, which suggests in theory that application of metal clips to the sympathetic chain is a reversible procedure if only the observation period is prolonged. Further studies with longer periods between application and removal as well as investigations of nerve conduction should be encouraged, because we do not know whether histological reversibility at cellular level translates into physiological reversibility and possible correlation of nerve trauma with the duration of the applied clip. © The Author 2014. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Two-Dimensional Electrophoretic Analysis of Subcellular Liver Fractions and Isolated Hepatocytes from Normal and PFDA Treated Rats

DTIC Science & Technology

1990-05-28

Continue on reverse if necessary and identify by block number) FIELD GROUP SUB-GROUP perfluoro.n-decanoic acid ; two-dimensional electrophoresis...hepatotoxicity; cell fractions; liver 1 t ABSTRACT (Continue on reverse if necessary and identify by block number) Perfluoro-n-decanoic acid (PFDA) effects...Unu::’-. ’. I AFOSR Ju .T , Building 410 Bolling AFB, DC 20332-6448 By Dist V’ lml mm mm i INTRODUCTION Perfluorocarboxylic acids and other

Should the United States Army Have a Professional General Staff?

DTIC Science & Technology

1987-03-23

SUPPLEMENTARY NOTES IS. KEY WORDS (Continue on reverse side if necessary and ldentlfy by block number) 20L ABSTRACT (Ceatu m orevere N nc wmy acd...Identify by block nember) 2ontinued on reverse side. 1’,..,* OR A 7 17 ED#-no,* OF INOV 6S IS OBSOLETE OF PG , ,.,. 3 .o o. ., N s. O. ETE SECURITY...Genius for 5 War: The German Army and General Staff 1807 - 1945. I do not intend to address org~ n ~zation. Most governments and * defense

A Cytological Analysis of the Antimetabolite Activity of 5-Hydroxyuracil in Vicia faba Roots

PubMed Central

Schreiber, Richard W.; Duncan, Robert E.

1958-01-01

The effects of 5-hydroxyuracil (5-HU) (isobarbituric acid) upon cell elongation, mitosis, and DNA synthesis were studied in Vicia faba roots. 5-HU had no consistent effect upon root elongation. It blocked DNA synthesis (analyzed by photometric measurements of Feulgen dye in nuclei) during the first 6 hours of treatment; the block spontaneously disappeared by the 12th hour of treatment. Uracil and thymine had no effect upon this block of synthesis. Both thymidine and uridine reversed the block in 6 and 9 hours respectively. In all cases blockage of DNA synthesis was followed by inhibition of mitosis (determined by changes in the percentage of cells in mitosis) and resumption of DNA synthesis was followed by resumption of mitosis. Inhibition indices calculated from the mitotic data indicated a competitive relationship between 5-HU and thymidine and 5-HU and uridine. 5-HU is considered to block DNA synthesis by competing with thymidine for sites on enzymes involved in the synthesis. It is suggested that uridine reverses the block in synthesis by undergoing a conversion to thymidine. PMID:13610946

Neurotoxins from venoms of the Hymenoptera--twenty-five years of research in Amsterdam.

PubMed

Piek, T

1990-01-01

1. In co-operation with colleagues in Europe, Japan and the U.S.A., 25 years of research in Amsterdam have provided new views on the way some hymenopteran insects incapacitate their prey by a diversity of neurotoxins, resulting in block of synaptic transmission in CNS or neuromuscular junctions, or affecting voltage dependent phenomena in nerve and muscle fibers. 2. Nicotinic synaptic transmission in the insect CNS is irreversibly blocked at the presynaptic side by kinins, or reversibly and postsynaptically blocked by philanthotoxins. 3. Glutamatergic neuromuscular transmission is reversibly blocked by philanthotoxins at the pre- and/or postsynaptic side. 4. A presynaptic block of neuromuscular transmission was found with the Microbracon toxins. 5. An irreversible deactivation, without paralysis, of cockroaches is caused by a sting of Ampulex compressa into the suboesophageal ganglion. 6. Poneratoxin, a 25 amino acid residue polypeptide, isolated from an ant venom, is the first described hymenopteran neurotoxin affecting excitability of nerve and muscle fibres by changing the kinetics of the voltage-dependent sodium channel.

Controlled Growth of CdS Quantum Dot in an Amphiphilic Diblock Copolymer Poly(2-Vinyl Pyridine)-b-Poly(n-Hexyl Isocyanate) Reversed Micelle Nanoreactor.

PubMed

Samal, Monica; Mohapatra, Priya Ranjan; Yun, Kyu Sik

2015-09-01

A diblock copolymer poly(2-vinyl pyridine)-b-poly(n-hexyl isocyanate) (P2VP-b-PHIC) is used for the present study. It has two blocks; a rod-shaped PHIC block that adopts a helical conformation, and a coil shaped P2VP block. In a polar solvent such as THF both PHIC and P2VP blocks are soluble. In mixtures of two solvents, such as THF and methanol, while the solubility of P2VP component is augmented that of PHIC is decreased leading to formation of reversed micelles. The pyridine nitrogen in P2VP block is a reactive site. It forms complexes with a suitable metal ion, such as Cd2+. The micelle is employed as a nanoreactor for synthesis of CdS quantum dot (QD). In this paper, the micellization behaviour of the copolymer and the use of the micelles for synthesis and controlled growth of CdS nanocrystals are demonstrated.

Recovery characteristics of patients receiving either sugammadex or neostigmine and glycopyrrolate for reversal of neuromuscular block: a randomised controlled trial.

PubMed

Paech, M J; Kaye, R; Baber, C; Nathan, E A

2018-03-01

Sugammadex more rapidly and reliably reverses rocuronium-induced neuromuscular block compared with neostigmine, but it is not known if subsequent patient outcomes, including nausea, vomiting and other aspects of recovery are modified. In this study, we compared the recovery characteristics of sugammadex and neostigmine/glycopyrrolate following reversal of neuromuscular block. This was a single-centre, randomised, blinded, parallel-group clinical trial in women undergoing elective day-surgical laparoscopic gynaecological surgery, with a standardised general anaesthesia regimen that included rocuronium. Neuromuscular block was reversed with either sugammadex 2 mg.kg -1 or neostigmine 40 μg.kg -1 and glycopyrrolate 400 μg. The primary outcome was the incidence of nausea and vomiting during the first six postoperative hours. Secondary outcomes included other measures of postoperative recovery such as patient symptoms and recovery scores. Three-hundred and four women were analysed by intention-to-treat (sugammadex n = 151, neostigmine n = 153), which included four major protocol violations. There was no significant difference between sugammadex and neostigmine groups in the incidence of early nausea and vomiting (49.0% vs. 51.0%, respectively; OR 0.92, 95%CI 0.59-1.45; p = 0.731). Double vision (11.5% vs. 20.0%; p = 0.044) and dry mouth (71.6% vs. 85.5%; p = 0.003) were less common after sugammadex. Sedation scores at 2 h were also lower after sugammadex (median (IQR [range]) 0 (0-3 [0-10]) vs. 2 (0-4.[0-10]); p = 0.021). Twenty-four-hour recovery scores were not significantly different between groups. Reversal with sugammadex in this patient population did not reduce postoperative nausea or vomiting compared with neostigmine/glycopyrrolate. © 2017 The Association of Anaesthetists of Great Britain and Ireland.

Preparation and evaluation of thin-film sodium tungsten bronzes

NASA Technical Reports Server (NTRS)

Kautz, H. E.; Fielder, W. L.; Singer, J.; Fordyce, J. S.

1974-01-01

Thin films of sodium tungsten bronze (NaxWO3) were investigated as reversible sodium ion electrodes for solid electrolytes. The films were made by electron beam evaporation of the three phases, W metal, Na2WO4, and WO3, followed by sintering. The substrates were sodium beta alumina disks and glass slides. X-ray diffraction analyses of the films showed that sintering in dry nitrogen with prior exposure to air lead to mixed phases. Sintering in vacuum with no air exposure produced tetragonal I bronze with a nominal composition of Na0.31WO3, single phase within the limits of X-ray diffraction detectability. The films were uniform and adherent on sodium beta alumina substrates. The ac and dc conductivities of the beta alumina were measured with the sodium tungsten bronze films as electrodes. These experiments indicated that the tetragonal I bronze electrodes were not completely reversible. This may have resulted from sodium ion blocking within the bronze film or at the bronze beta alumina interface. Methods for attempting to make more completely reversible electrodes are suggested.

An anion channel in Arabidopsis hypocotyls activated by blue light

NASA Technical Reports Server (NTRS)

Cho, M. H.; Spalding, E. P.; Evans, M. L. (Principal Investigator)

1996-01-01

A rapid, transient depolarization of the plasma membrane in seedling stems is one of the earliest effects of blue light detected in plants. It appears to play a role in transducing blue light into inhibition of hypocotyl (stem) elongation, and perhaps other responses. The possibility that activation of a Cl- conductance is part of the depolarization mechanism was raised previously and addressed here. By patch clamping hypocotyl cells isolated from dark-grown (etiolated) Arabidopsis seedlings, blue light was found to activate an anion channel residing at the plasma membrane. An anion-channel blocker commonly known as NPPB 15-nitro-2-(3-phenylpropylamino)-benzoic acid] potently and reversibly blocked this anion channel. NPPB also blocked the blue-light-induced depolarization in vivo and decreased the inhibitory effect of blue light on hypocotyl elongation. These results indicate that activation of this anion channel plays a role in transducing blue light into growth inhibition.

Mesoporous Ge/GeO2/Carbon Lithium-Ion Battery Anodes with High Capacity and High Reversibility.

PubMed

Hwang, Jongkook; Jo, Changshin; Kim, Min Gyu; Chun, Jinyoung; Lim, Eunho; Kim, Seongseop; Jeong, Sanha; Kim, Youngsik; Lee, Jinwoo

2015-05-26

We report mesoporous composite materials (m-GeO2, m-GeO2/C, and m-Ge-GeO2/C) with large pore size which are synthesized by a simple block copolymer directed self-assembly. m-Ge/GeO2/C shows greatly enhanced Coulombic efficiency, high reversible capacity (1631 mA h g(-1)), and stable cycle life compared with the other mesoporous and bulk GeO2 electrodes. m-Ge/GeO2/C exhibits one of the highest areal capacities (1.65 mA h cm(-2)) among previously reported Ge- and GeO2-based anodes. The superior electrochemical performance in m-Ge/GeO2/C arises from the highly improved kinetics of conversion reaction due to the synergistic effects of the mesoporous structures and the conductive carbon and metallic Ge.

Photo-responsive block copolymer micelles: design and behavior.

PubMed

Gohy, Jean-François; Zhao, Yue

2013-09-07

Stimuli-responsive block copolymer micelles are the topic of intense research since they are able to show sharp and eventually reversible responses to various environmental changes and find applications in various fields including controlled drug delivery. Among all the available stimuli, light has recently attracted much attention since it can be localized in time and space, and it can also be triggered from outside of the system. In this tutorial review, we highlight the progress realized in recent years. More precisely, we provide some guidelines towards the rational design of photo-responsive block copolymers and we present the different photo-responsive moieties that have been used so far. We also discuss the different types of irreversible and reversible responses encountered by photo-responsive block copolymer micelles. Finally, we suggest possible future developments including the design of biocompatible systems operating at excitation wavelengths compatible for biomedical applications.

Nonvesicular inhibitory neurotransmission via reversal of the GABA transporter GAT-1

PubMed Central

Wu, Yuanming; Wang, Wengang; Díez-Sampedro, Ana; Richerson, George B.

2007-01-01

SUMMARY GABA transporters play an important but poorly understood role in neuronal inhibition. They can reverse, but this is widely thought to occur only under pathological conditions. Here we use a heterologous expression system to show that the reversal potential of GAT-1 under physiologically relevant conditions is near the normal resting potential of neurons, and that reversal can occur rapidly enough to release GABA during simulated action potentials. We then use paired recordings from cultured hippocampal neurons, and show that GABAergic transmission is not prevented by four methods widely used to block vesicular release. This nonvesicular neurotransmission was potently blocked by GAT-1 antagonists, and was enhanced as predicted by agents that increase cytosolic [GABA] or [Na+]. The results indicate that GAT-1 regulates tonic inhibition by clamping ambient [GABA] at a level high enough to activate high affinity GABAA receptors, and that transporter-mediated GABA release can contribute to phasic inhibition. PMID:18054861

Aqueous dispersion polymerization: a new paradigm for in situ block copolymer self-assembly in concentrated solution.

PubMed

Sugihara, Shinji; Blanazs, Adam; Armes, Steven P; Ryan, Anthony J; Lewis, Andrew L

2011-10-05

Reversible addition-fragmentation chain transfer polymerization has been utilized to polymerize 2-hydroxypropyl methacrylate (HPMA) using a water-soluble macromolecular chain transfer agent based on poly(2-(methacryloyloxy)ethylphosphorylcholine) (PMPC). A detailed phase diagram has been elucidated for this aqueous dispersion polymerization formulation that reliably predicts the precise block compositions associated with well-defined particle morphologies (i.e., pure phases). Unlike the ad hoc approaches described in the literature, this strategy enables the facile, efficient, and reproducible preparation of diblock copolymer spheres, worms, or vesicles directly in concentrated aqueous solution. Chain extension of the highly hydrated zwitterionic PMPC block with HPMA in water at 70 °C produces a hydrophobic poly(2-hydroxypropyl methacrylate) (PHPMA) block, which drives in situ self-assembly to form well-defined diblock copolymer spheres, worms, or vesicles. The final particle morphology obtained at full monomer conversion is dictated by (i) the target degree of polymerization of the PHPMA block and (ii) the total solids concentration at which the HPMA polymerization is conducted. Moreover, if the targeted diblock copolymer composition corresponds to vesicle phase space at full monomer conversion, the in situ particle morphology evolves from spheres to worms to vesicles during the in situ polymerization of HPMA. In the case of PMPC(25)-PHPMA(400) particles, this systematic approach allows the direct, reproducible, and highly efficient preparation of either block copolymer vesicles at up to 25% solids or well-defined worms at 16-25% solids in aqueous solution.

Enantiopure heterobimetallic single-chain magnets from the chiral Ru(III) building block.

PubMed

Ru, Jing; Gao, Feng; Wu, Tao; Yao, Min-Xia; Li, Yi-Zhi; Zuo, Jing-Lin

2014-01-21

A pair of one-dimensional enantiomers based on the versatile chiral dicyanoruthenate(III) building block have been synthesized and they are chiral single-chain magnets with the effective spin-reversal barrier of 28.2 K.

P-type Ca2+ channels mediate excitatory and inhibitory synaptic transmitter release in crayfish muscle.

PubMed

Araque, A; Clarac, F; Buño, W

1994-05-10

The toxin fraction (FTX) and peptide omega-Aga-IVA from the venom of the funnel-web spider Agelenopsis aperta, as well as a synthetic analogue of FTX, specifically block the P-type voltage-dependent Ca2+ channel (VDCC). The effects of these toxins on synaptic transmission were studied in the neuromuscular synapses of the crayfish opener muscle, which has a single excitatory and a single inhibitory motoneuron. FTX selectively and reversibly blocked excitatory and inhibitory postsynaptic currents and potentials in a dose-dependent manner. FTX had no effect on (i) resting and postsynaptic membrane conductance, (ii) postsynaptic L-type VDCC, and (iii) both glutamate- and gamma-aminobutyric acid-induced postsynaptic responses. Mean amplitude and frequency of miniature postsynaptic potentials were unchanged by FTX. The postsynaptic VDCC was inhibited by nifedipine, a selective dihydropyridine antagonist of L-type VDCC, whereas synaptic transmission was unaffected. Transmission was also undisturbed by omega-conotoxin, suggesting that N-type VDCCs are not involved. The peptide omega-Aga-IVA blocked excitatory and inhibitory transmission without affecting postsynaptic VDCC. Synaptic transmission was also blocked by synthetic FTX. We conclude that presynaptic P-type VDCCs are involved in both evoked excitatory and inhibitory transmitter release in crayfish neuromuscular synapses.

P-type Ca2+ channels mediate excitatory and inhibitory synaptic transmitter release in crayfish muscle.

PubMed Central

Araque, A; Clarac, F; Buño, W

1994-01-01

The toxin fraction (FTX) and peptide omega-Aga-IVA from the venom of the funnel-web spider Agelenopsis aperta, as well as a synthetic analogue of FTX, specifically block the P-type voltage-dependent Ca2+ channel (VDCC). The effects of these toxins on synaptic transmission were studied in the neuromuscular synapses of the crayfish opener muscle, which has a single excitatory and a single inhibitory motoneuron. FTX selectively and reversibly blocked excitatory and inhibitory postsynaptic currents and potentials in a dose-dependent manner. FTX had no effect on (i) resting and postsynaptic membrane conductance, (ii) postsynaptic L-type VDCC, and (iii) both glutamate- and gamma-aminobutyric acid-induced postsynaptic responses. Mean amplitude and frequency of miniature postsynaptic potentials were unchanged by FTX. The postsynaptic VDCC was inhibited by nifedipine, a selective dihydropyridine antagonist of L-type VDCC, whereas synaptic transmission was unaffected. Transmission was also undisturbed by omega-conotoxin, suggesting that N-type VDCCs are not involved. The peptide omega-Aga-IVA blocked excitatory and inhibitory transmission without affecting postsynaptic VDCC. Synaptic transmission was also blocked by synthetic FTX. We conclude that presynaptic P-type VDCCs are involved in both evoked excitatory and inhibitory transmitter release in crayfish neuromuscular synapses. Images PMID:7910404

Mechanisms of pro-arrhythmic abnormalities in ventricular repolarisation and anti-arrhythmic therapies in human hypertrophic cardiomyopathy.

PubMed

Passini, Elisa; Mincholé, Ana; Coppini, Raffaele; Cerbai, Elisabetta; Rodriguez, Blanca; Severi, Stefano; Bueno-Orovio, Alfonso

2016-07-01

Hypertrophic cardiomyopathy (HCM) is a cause of sudden arrhythmic death, but the understanding of its pro-arrhythmic mechanisms and an effective pharmacological treatment are lacking. HCM electrophysiological remodelling includes both increased inward and reduced outward currents, but their role in promoting repolarisation abnormalities remains unknown. The goal of this study is to identify key ionic mechanisms driving repolarisation abnormalities in human HCM, and to evaluate anti-arrhythmic effects of single and multichannel inward current blocks. Experimental ionic current, action potential (AP) and Ca(2+)-transient (CaT) recordings were used to construct populations of human non-diseased and HCM AP models (n=9118), accounting for inter-subject variability. Simulations were conducted for several degrees of selective and combined inward current block. Simulated HCM cardiomyocytes exhibited prolonged AP and CaT, diastolic Ca(2+) overload and decreased CaT amplitude, in agreement with experiments. Repolarisation abnormalities in HCM models were consistently driven by L-type Ca(2+) current (ICaL) re-activation, and ICaL block was the most effective intervention to normalise repolarisation and diastolic Ca(2+), but compromised CaT amplitude. Late Na(+) current (INaL) block partially abolished repolarisation abnormalities, with small impact on CaT. Na(+)/Ca(2+) exchanger (INCX) block effectively restored repolarisation and CaT amplitude, but increased Ca(2+) overload. Multichannel block increased efficacy in normalising repolarisation, AP biomarkers and CaT amplitude compared to selective block. Experimentally-calibrated populations of human AP models identify ICaL re-activation as the key mechanism for repolarisation abnormalities in HCM, and combined INCX, INaL and ICaL block as effective anti-arrhythmic therapies also able to partially reverse the HCM electrophysiological phenotype. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Fluorescence Lifetime Study of Cyclodextrin Complexes of Substituted Naphthalenes.

DTIC Science & Technology

1987-08-15

Spectroscopy iip 17. COSATI CODES 18. SUBJECT TERMS (Continue on reverse If necessary and identify by block number) FIELD GROUP SUB-GROUP fluorescence lifetime...measurements cyclodextrins spectroscopic techniques 19. TRACT (Continue on revere if necsary and identify by block number

Late Triassic paleolatitude of the Qiangtang block: Implications for the closure of the Paleo-Tethys Ocean

NASA Astrophysics Data System (ADS)

Song, Peiping; Ding, Lin; Li, Zhenyu; Lippert, Peter C.; Yang, Tianshui; Zhao, Xixi; Fu, Jiajun; Yue, Yahui

2015-08-01

To better constrain the Late Triassic paleolatitude of the Qiangtang block and the closure of the Paleo-Tethys Ocean, a combined paleomagnetic and zircon U/Pb geochronological study has been conducted on the Upper Triassic Jiapila Formation volcanic rocks on the northern edge of the Qiangtang block of Central Tibet (34.1°N, 92.4°E). These rocks are dated to 204-213 Ma. Progressive thermal or alternating field demagnetization successfully isolated stable characteristic remanent magnetizations (ChRM) that pass both the fold and reversal tests, consistent with a primary magnetization. These are the first volcanic-based paleomagnetic results from pre-Cretaceous rocks of the Qiangtang block that appear to average secular variation well enough to yield a reliable paleolatitude estimate. Based on our new paleomagnetic data from Upper Triassic lavas, we conclude that the Late Triassic pole of the Qiangtang block was located at 64.0°N, 174.7°E, with A95 = 6.6 ° (N = 29). We compile published paleomagnetic data from the Qiangtang block to calculate a Late Triassic latitude for the Qiangtang block at 31.7 ± 3.0°N. The central Paleo-Tethys Ocean basin was located between the North China (NCB) and Tarim blocks to the north and the Qiangtang block to the south during Late Paleozoic-Early Mesozoic. A comparison of published Early Triassic paleopole from the Qiangtang block with the coeval paleopoles from the NCB and Tarim indicates that the Paleo-Tethys Ocean could not have closed during the Early Triassic and that its width was approximately ∼32-38° latitude (∼3500-4200 km). However, the comparison of our new combined Late Triassic paleomagnetic result with the Late Triassic poles of the NCB and Tarim, as well as numerous geological observations, indicates that the closure of the Paleo-Tethys Ocean at the longitude of the Qiangtang block most likely occurred during the Late Triassic.

The use of blocking screws with internal lengthening nail and reverse rule of thumb for blocking screws in limb lengthening and deformity correction surgery.

PubMed

Muthusamy, Saravanaraja; Rozbruch, S Robert; Fragomen, Austin T

2016-11-01

Internal lengthening nail (ILN) is a recent development in limb lengthening and deformity correction specialty. The ILN has the distinct advantage of combining acute deformity correction with gradual lengthening of bone. While using ILN, the short metaphyseal bone fragment may develop a deformity at the time of osteotomy and nail insertion or during bone lengthening because of the wide medullary canal. These deformities are typically predictable, and blocking screws (Poller screws) are helpful in these situations. This manuscript describes the common deformities that occur in femur and tibia with osteotomies at different locations while using ILN in antegrade and retrograde nailing technique. Also, a systematic approach to the appropriate use of blocking screws in these deformities is described. In addition, the "reverse rule of thumb" is introduced as a quick reference to determine the ideal location(s) and number of blocking screws. These principles are applicable to limb lengthening and deformity correction as well as fracture fixation using intramedullary nails.

Sweet taste transduction in hamster: sweeteners and cyclic nucleotides depolarize taste cells by reducing a K+ current.

PubMed

Cummings, T A; Daniels, C; Kinnamon, S C

1996-03-01

1. The gigaseal voltage-clamp technique was used to record responses of hamster taste receptor cells to synthetic sweeteners and cyclic nucleotides. Voltage-dependent currents and steady-state currents were monitored during bath exchanges of saccharin, two high-potency sweeteners, 8-chlorophenylthio-adenosine 3',5'-cyclic monophosphate (8cpt-cAMP), and dibutyryl-guanosine 3',5'-cyclic monophosphate (db-cGMP). 2. Of the 237 fungiform taste cells studied, only one in eight was sweet responsive. Outward currents, both voltage-dependent and resting, were reduced by all of the sweeteners tested in sweet-responsive taste cells, whereas these currents were unaffected by sweeteners in sweet-unresponsive taste cells. 3. In every sweet-responsive cell tested, 8cpt-cAMP and db-cGMP mimicked the response to the sweeteners, but neither nucleotide elicited responses in sweet-unresponsive cells. Thus there was a one-to-one correlation between sweet responsivity and cyclic nucleotide responsivity. 4. Sweet responses showed cross adaptation with cyclic nucleotide responses. This indicates that the same ion channel is modulated by sweeteners and cyclic nucleotides. 5. The sweetener- and cyclic nucleotide-blocked current had an apparent reversal potential of -50 mV, which was close to the potassium reversal potential in these experiments. In addition, there was no effect of sweeteners and cyclic nucleotides in the presence of the K+ channel blocker tetraethylammonium bromide (TEA). These data suggest that block of a resting, TEA-sensitive K+ current is the final common step leading to taste cell depolarization during sweet transduction. 6. These data, together with data from a previous study (Cummings et al. 1993), suggest that both synthetic sweeteners and sucrose utilize second-messenger pathways that block a resting K+ conductance to depolarize the taste cell membrane.

A Proposed Direction Finding and Polarization Sensing Scheme.

DTIC Science & Technology

1976-03-01

on ’:i J -v nor any ’.o tion 4-u rn s e c, c. in a ,y x ay su-.plie soi a. cdl nir ino g cvsci f icati o-c, in ar"r’. mnner C o the >o d r c ,,,o-,r...SUPPLEMENTARY NOTES 19. KEY WORDS (Continue on reverse aide iI necessary and identify by block number) Direction-findingi t Polarization-sensing Small...antenna array 20. ABS CT (Continue on reverse aide If necesaery and identify by block number) This report proposes and demonstrates a direction finding

Dilated cardiomyopathy and left bundle branch block associated with ingestion of colloidal gold and silver is reversed by British antiLewisite and vitamin E: The potential toxicity of metals used as health supplements

PubMed Central

Archer, Stephen Lawrence

2008-01-01

A case of left bundle branch block and a dilated, nonhypertrophic cardiomyopathy associated with ingestion of colloidal gold and silver as an ‘energy tonic’ is described. The cardiac disease was reversed within two months by a course of dimercaprol (Akorn Inc, USA) (British antiLewisite) and vitamin E. This is the first case of gold and silver cardiomyopathy in humans, and highlights the risks of these colloidal metal ‘health supplements’. PMID:18464946

Characterization of a Poly(styrene-block-methylacrylate-random-octadecylacrylate-block-styrene) Shape Memory ABA Triblock Copolymer

NASA Astrophysics Data System (ADS)

Fei, Pengzhan; Cavicchi, Kevin

2011-03-01

A new ABA triblock copolymer of poly(styrene-block- methylacrylate-random-octadecylacrylate-block-styrene) (PS-b- PMA-r-PODA-b-PS) was synthesized by reversible addition fragmentation chain transfer polymerization. The triblock copolymer can generate a three-dimensional, physically crosslinked network by self-assembly, where the glassy PS domains physically crosslink the midblock chains. The side chain crystallization of the polyoctadecylacrylare (PODA) side chain generates a second reversible network enabling shape memory properties. Shape memory tests by uniaxial deformation and recovery of molded dog-bone shape samples demonstrate that shape fixities above 96% and shape recoveries above 98% were obtained for extensional strains up to 300%. An outstanding advantage of this shape memory material is that it can be very easily shaped and remolded by elevating the temperature to 140circ; C, and after remolding the initial shape memory properties are totally recovered by eliminating the defects introduced by the previous deformation cycling.

Evidence for single metal two electron oxidative addition and reductive elimination at uranium.

PubMed

Gardner, Benedict M; Kefalidis, Christos E; Lu, Erli; Patel, Dipti; McInnes, Eric J L; Tuna, Floriana; Wooles, Ashley J; Maron, Laurent; Liddle, Stephen T

2017-12-01

Reversible single-metal two-electron oxidative addition and reductive elimination are common fundamental reactions for transition metals that underpin major catalytic transformations. However, these reactions have never been observed together in the f-block because these metals exhibit irreversible one- or multi-electron oxidation or reduction reactions. Here we report that azobenzene oxidises sterically and electronically unsaturated uranium(III) complexes to afford a uranium(V)-imido complex in a reaction that satisfies all criteria of a single-metal two-electron oxidative addition. Thermolysis of this complex promotes extrusion of azobenzene, where H-/D-isotopic labelling finds no isotopomer cross-over and the non-reactivity of a nitrene-trap suggests that nitrenes are not generated and thus a reductive elimination has occurred. Though not optimally balanced in this case, this work presents evidence that classical d-block redox chemistry can be performed reversibly by f-block metals, and that uranium can thus mimic elementary transition metal reactivity, which may lead to the discovery of new f-block catalysis.

Dexamethasone does not diminish sugammadex reversal of neuromuscular block - clinical study in surgical patients undergoing general anesthesia.

PubMed

Rezonja, Katja; Mars, Tomaz; Jerin, Ales; Kozelj, Gordana; Pozar-Lukanovic, Neva; Sostaric, Maja

2016-10-21

Sugammadex reverses neuromuscular block (NMB) through binding aminosteroid neuromuscular blocking agents. Although sugammadex appears to be highly selective, it can interact with other drugs, like corticosteroids. A prospective single-blinded randomized clinical trial was designed to explore the significance of interactions between dexamethasone and sugammadex. Sixty-five patients who were anesthetized for elective abdominal or urological surgery were included. NMB was assessed using train-of-four stimulation (TOF), with rocuronium used to maintain the desired NMB depth. NMB reversal at the end of anaesthesia was achieved using sugammadex. According to their received antiemetics, the patients were randomized to either the granisetron or dexamethasone group. Blood samples were taken before and after NMB reversal, for plasma dexamethasone and rocuronium determination. Primary endpoint was time from sugammadex administration to NMB reversal. Secondary endpoints included the ratios of the dexamethasone and rocuronium concentrations after NMB reversal versus before sugammadex administration. There were no differences for time to NMB reversal between the control (mean 121 ± 61 s) and the dexamethasone group (mean 125 ± 57 s; P = 0.760). Time to NMB reversal to a TOF ratio ≥0.9 was significantly longer in patients with lower TOF prior to sugammadex administration (Beta = -0.268; P = 0.038). The ratio between the rocuronium concentrations after NMB reversal versus before sugammadex administration was significantly affected by sugammadex dose (Beta = -0.375; P = 0.004), as was rocuronium dose per hour of operation (Beta = -0.366; p = 0.007), while it was not affected by NMB depth before administration of sugammadex (Beta = -0.089; p = 0.483) and dexamethasone (Beta = -0.186; p = 0.131). There was significant drop in plasma dexamethasone after sugammadex administration and NMB reversal (p < 0.001). Administration of dexamethasone to anesthetized patients did not delay NMB reversal by sugammadex. The trial was retrospectively registered with The Australian New Zealand Clinical Trials Registry (ANZCTR) on February 28th 2012 (enrollment of the first patient on February 2nd 2012) and was given a trial ID number ACTRN12612000245897 and universal trial number U1111-1128-5104.

Early-onset Lyme carditis with concurrent disseminated erythema migrans.

PubMed

Patel, Kinjan P; Farjo, Peter D; Juskowich, Joy J; Hama Amin, Ali; Mills, James D

2017-01-01

Lyme disease is an infection that is estimated to affect over 300,000 people in the United States annually. Typically, it presents with erythema migrans (EM), an annular rash at the site of tick attachment, within 3 to 30 days of inoculation. Untreated patients may progress to early disseminated disease. A further complication, Lyme carditis is rare but may occur several weeks later. It commonly manifests as a variable atrioventricular (AV) conduction block, with a high-grade AV block occurring in only 1% of untreated patients. This case demonstrates an unusually early presentation of Lyme carditis with complete heart block. A 21-year-old male was transferred from an outside emergency department (ED) for possible pacemaker placement due to symptomatic third-degree AV block. Four days earlier the patient presented to the outside ED with fever, chills, and unrecognized EM on his right neck. He was discharged with antipyretics, but no antibiotic therapy. On the day of transfer, he returned with persistent fevers, EM now on his trunk and upper extremities, lightheadedness, and substernal chest pressure. An electrocardiogram revealed the third-degree AV block leading to transfer. Upon arrival, the patient was promptly diagnosed with Lyme carditis. Pacemaker implantation was deferred, and intravenous (IV) ceftriaxone was initiated. Within 48 hours his third-degree AV block improved to a first-degree block. By this time, his EM had also resolved. He was discharged with oral doxycycline and a 30-day event monitor, which ultimately showed persistent first-degree AV block. This case reinforces a unique presentation of Lyme carditis. Disseminated EM and Lyme carditis may present concurrently within 2 weeks of tick attachment. Early recognition and treatment is important for preventing progression to disseminated infection. Lyme-associated AV block will reverse within 48 to 72 hours of initiating IV antibiotic therapy and will not require pacemaker implantation. Lyme carditis should be considered in patients without heart disease who present with any degree of AV block.

Non-immunogenic, hydrophilic/cationic block copolymers and uses thereof

DOEpatents

Scales, Charles W.; Huang, Faqing; McCormick, Charles L.

2010-05-18

The present invention provides novel non-immunogenic, hydrophilic/cationic block copolymers comprising a neutral-hydrophilic polymer and a cationic polymer, wherein both polymers have well-defined chain-end functionality. A representative example of such a block copolymer comprises poly(N-(2-hydroxypropyl)methacrylamide) (PHPMA) and poly(N-[3-(dimethylamino)propyl]methacrylamide) (PDMAPMA). Also provided is a synthesis method thereof in aqueous media via reversible addition fragmentation chain transfer (RAFT) polymerization. Further provided are uses of these block copolymers as drug delivery vehicles and protection agents.

Self-doped microphase separated block copolymer electrolyte

DOEpatents

Mayes, Anne M.; Sadoway, Donald R.; Banerjee, Pallab; Soo, Philip; Huang, Biying

2002-01-01

A polymer electrolyte includes a self-doped microphase separated block copolymer including at least one ionically conductive block and at least one second block that is immiscible in the ionically conductive block, an anion immobilized on the polymer electrolyte and a cationic species. The ionically conductive block provides a continuous ionically conductive pathway through the electrolyte. The electrolyte may be used as an electrolyte in an electrochemical cell.

Lyme Carditis Buried Beneath ST-Segment Elevations

PubMed Central

Umpierrez De Reguero, Adrian

2017-01-01

Lyme disease is caused by the spirochete Borrelia burgdorferi and is carried to human hosts by infected ticks. There are nearly 30,000 cases of Lyme disease reported to the CDC each year, with 3-4% of those cases reporting Lyme carditis. The most common manifestation of Lyme carditis is partial heart block following bacterial-induced inflammation of the conducting nodes. Here we report a 45-year-old gentleman that presented to the hospital with intense nonradiating chest pressure and tightness. Lab studies were remarkable for elevated troponins. EKG demonstrated normal sinus rhythm with mild ST elevations. Three weeks prior to hospital presentation, patient had gone hunting near Madison. One week prior to admission, he noticed an erythematous lesion on his right shoulder. Because of his constellation of history, arthralgias, and carditis, he was started on ceftriaxone to treat probable Lyme disease. This case illustrates the importance of thorough history taking and extensive physical examination when assessing a case of possible acute myocardial infarction. Because Lyme carditis is reversible, recognition of this syndrome in young patients, whether in the form of AV block, myocarditis, or acute myocardial ischemia, is critical to the initiation of appropriate antibiotics in order to prevent permanent heart block, or even death. PMID:28713599

OcyKTx2, a new K⁺-channel toxin characterized from the venom of the scorpion Opisthacanthus cayaporum.

PubMed

Schwartz, Elisabeth F; Bartok, Adam; Schwartz, Carlos Alberto; Papp, Ferenc; Gómez-Lagunas, Froylan; Panyi, Gyorgy; Possani, Lourival D

2013-08-01

Opisthacanthus cayaporum belongs to the Liochelidae family, and the scorpions from this genus occur in southern Africa, Central America and South America and, therefore, can be considered a true Gondwana heritage. In this communication, the isolation, primary structure characterization, and K⁺-channel blocking activity of new peptide from this scorpion venom are reported. OcyKTx2 is a 34 amino acid long peptide with four disulfide bridges and molecular mass of 3807 Da. Electrophysiological assays conducted with pure OcyKTx2 showed that this toxin reversibly blocks Shaker B K⁺-channels with a Kd of 82 nM, and presents an even better affinity toward hKv1.3, blocking it with a Kd of ∼18 nM. OcyKTx2 shares high sequence identity with peptides belonging to subfamily 6 of α-KTxs that clustered very closely in the phylogenetic tree included here. Sequence comparison, chain length and number of disulfide bridges analysis classify OcyKTx2 into subfamily 6 of the α-KTx scorpion toxins (systematic name, α-KTx6.17). Copyright © 2013 Elsevier Inc. All rights reserved.

Peripheral neuropathy in Tangier disease: A literature review and assessment.

PubMed

Mercan, Metin; Yayla, Vildan; Altinay, Serdar; Seyhan, Serhat

2018-06-01

Tangier disease (TD) (OMIM#205400) is a rare cause of inherited metabolic neuropathies characterized by marked deficiency of high-density lipoproteins and accumulation of cholesterol esters in various tissue resulting from reverse cholesterol transport deficiency. We report a case of a patient with TD with multifocal demyelinating neuropathy with conduction block who presents with winging scapula, tongue, and asymmetric extremity weakness. We also present a review of all studies published from 1960 to 2017 regarding peripheral neuropathy in TD. Our search identified 54 patients with TD with peripheral neuropathy. Syringomyelia-like neuropathy subtype (52.4%) was more frequent than multifocal sensorial and motor neuropathy subtype (26.2%), focal neuropathy subtype (19.1%), and distal symmetric polyneuropathy subtype (2.4%). Splenomegaly was the most common (40.7%) clinical manifestation in these patients. The pattern of electrodiagnostic abnormalities are: (1) demyelinating abnormalities were more predominant in the upper extremities than in the lower extremities and (2) slowing of motor nerve conduction was more prominent in the intermediate segment than in distal nerve segments. The sural-sparing pattern was present in 34.6% and conduction block was present in 11.5% of the patients. Our literature review and our case showed the clinical spectrum of TD neuropathy is quite wide and that it should be considered in the differential diagnosis of non-uniform demyelinating neuropathies. © 2018 Peripheral Nerve Society.

Reversible switch between the nanoporous and the nonporous state of amphiphilic block copolymer films regulated by selective swelling.

PubMed

Yan, Nina; Wang, Yong

2015-09-21

Switchable nanoporous films, which can repeatedly alternate their porosities, are of great interest in a diversity of fields. Currently these intelligent materials are mostly based on polyelectrolytes and their porosities can change only in relatively narrow ranges, typically under wet conditions, severely limiting their applications. Here we develop a new system, which is capable of reversibly switching between a highly porous state and a nonporous state dozens of times regulated simply by exposure to selective solvents. In this system nanopores are created or reversibly eliminated in films of a block copolymer, polystyrene-block-poly(2-vinyl pyridine) (PS-b-P2VP), by exposing the films to P2VP-selective or PS-selective solvents, respectively. The mechanism of the switch is based on the selective swelling of the constituent blocks in corresponding solvents, which is a nondestructive and easily controllable process enabling the repeatable and ample switch between the open and the closed state. Systematic microscopic and ellipsometric characterization methods are performed to elucidate the pore-closing course induced by nonsolvents and the cycling between the pore-open and the pore-closed state up to 20 times. The affinity of the solvent for PS blocks is found to play a dominating role in determining the pore-closing process and the porosities of the pore-open films increase with the cycling numbers as a result of loose packing conditions of the polymer chains. We finally demonstrate the potential applications of these films as intelligent antireflection coatings and drug carriers.

Feedback Effects in Computer-Based Skill Learning

DTIC Science & Technology

1989-09-12

SUPPLEMENTARY NOTATION 17 COSATI CODES 18 SUBJECT TERMS (Continue on reverse if necessary and identify by block number) r FIELD GROUP SUB-GROUP I...rather than tangible feedback ( Barringer & Gholson, 1979) and when they receive punishment (either alone or witih reward) rather than reward alone...34graphed" response latencies across the four conditions ( r = .58), indicating that subjects were sensitive to block-by-block trends in their response

Method of making high breakdown voltage semiconductor device

DOEpatents

Arthur, Stephen D.; Temple, Victor A. K.

1990-01-01

A semiconductor device having at least one P-N junction and a multiple-zone junction termination extension (JTE) region which uniformly merges with the reverse blocking junction is disclosed. The blocking junction is graded into multiple zones of lower concentration dopant adjacent termination to facilitate merging of the JTE to the blocking junction and placing of the JTE at or near the high field point of the blocking junction. Preferably, the JTE region substantially overlaps the graded blocking junction region. A novel device fabrication method is also provided which eliminates the prior art step of separately diffusing the JTE region.

Un-Building Blocks: A Model of Reverse Engineering and Applicable Heuristics

DTIC Science & Technology

2015-12-01

CONCLUSIONS The machine does not isolate man from the great problems of nature but plunges him more deeply into them. Antoine de Saint-Exupery— Wind ...DISTRIBUTION CODE 13. ABSTRACT (maximum 200 words) Reverse engineering is the problem -solving activity that ensues when one takes a...Douglas Moses, Vice Provost for Academic Affairs iv THIS PAGE INTENTIONALLY LEFT BLANK v ABSTRACT Reverse engineering is the problem -solving

RAFT polymerization of temperature- and salt-responsive block copolymers as reversible hydrogels.

PubMed

Hemp, Sean T; Smith, Adam E; Bunyard, W Clayton; Rubinstein, Michael H; Long, Timothy E

2014-05-13

Reversible-addition fragmentation chain transfer (RAFT) polymerization enabled the synthesis of novel, stimuli-responsive, AB and ABA block copolymers. The B block contained oligo(ethylene glycol) methyl ether methacrylate (OEG) and was permanently hydrophilic in the conditions examined. The A block consisted of diethylene glycol methyl ether methacrylate (DEG) and [2-(methacryloyloxy)ethyl]trimethylammonium chloride (TMA). The A block displayed both salt- and temperature-response with lower critical solution temperatures (LCSTs) dependent on the molar content of TMA and the presence of salt. Higher TMA content in the AB diblock copolymers increased the critical micelle temperatures (CMT) in HPLC-grade water due to an increased hydrophilicity of the A block. Upon addition of 0.9 wt% NaCl, the CMTs of poly(OEG- b -DEG 95 TMA 5 ) decreased from 50 °C to 36 °C due to screening of electrostatic repulsion between the TMA units. ABA triblock copolymers displayed excellent hydrogel properties with salt- and temperature-dependent gel points. TMA incorporation in the A block increased the gel points for all triblock copolymers, and salt-response increased with higher TMA composition in the A block. For example, poly(DEG 98 TMA 2 - b -OEG- b -DEG 98 TMA 2 ) formed a hydrogel at 40 °C in HPLC-grade water and 26 °C in 0.9 wt% NaCl aqueous solution. These salt- and temperature-responsive AB diblock and ABA triblock copolymers find applications as drug delivery vehicles, adhesives, and hydrogels.

An Airborne Programmable Digital to Video Converter Interface and Operation Manual.

DTIC Science & Technology

1981-02-01

Identify by block number) SCAN CONVERTER VIDEO DISPLAY TELEVISION DISPLAY 20. ABSTRACT (Continue on reverse oide If necessary and Identify by block...programmable cathode ray tube (CRT) controller which is accessed by the CPU to permit operation in a wide variety of modes. The Alphanumeric Generator

Near-infrared selective dynamic windows controlled by charge transfer impedance at the counter electrode.

PubMed

Pattathil, Praveen; Scarfiello, Riccardo; Giannuzzi, Roberto; Veramonti, Giulia; Sibillano, Teresa; Qualtieri, Antonio; Giannini, Cinzia; Cozzoli, P Davide; Manca, Michele

2016-12-08

Recent developments in the exploitation of transparent conductive oxide nanocrystals paved the way to the realization of a new class of electrochemical systems capable of selectively shielding the infrared heat loads carried by sunlight and prospected the blooming of a key enabling technology to be implemented in the next generation of "zero-energy" building envelopes. Here we report the fabrication of a set of electrochromic devices embodying an engineered nanostructured electrode made by high aspect-ratio tungsten oxide nanorods, which allow for selectively and dynamically controlling sunlight transmission over the near-infrared to visible range. Varying the intensity of applied voltage makes the spectral response of the device change across three different optical regimes, namely fully transparent, near-infrared only blocking and both visible and near-infrared blocking. It is demonstrated that the degree of reversible modulation of the thermal radiation entering the glazing element can approach a remarkable 85%, accompanied by only a modest reduction in the luminous transmittance.

Base drive circuit for a four-terminal power Darlington

DOEpatents

Lee, Fred C.; Carter, Roy A.

1983-01-01

A high power switching circuit which utilizes a four-terminal Darlington transistor block to improve switching speed, particularly in rapid turn-off. Two independent reverse drive currents are utilized during turn off in order to expel the minority carriers of the Darlington pair at their own charge sweep-out rate. The reverse drive current may be provided by a current transformer, the secondary of which is tapped to the base terminal of the power stage of the Darlington block. In one application, the switching circuit is used in each power switching element in a chopper-inverter drive of an electric vehicle propulsion system.

Extradural cold block for selective neurostimulation of the bladder: development of a new technique.

PubMed

Schumacher, S; Bross, S; Scheepe, J R; Seif, C; Jünemann, K P; Alken, P

1999-03-01

Cryotechnique for selective block of the urethral sphincter and simultaneous activation of the bladder was developed to achieve physiological micturition during sacral anterior root stimulation (SARS). In ten foxhounds SARS of S2 was carried out while extradurally both spinal nerves S2 were cooled down from positive 25C in a stepwise fashion until a sphincter block was observed. Subsequently, SARS of S2 was performed while the pudendal nerves were cooled down from + 15C. The effects of spinal and pudendal nerve cold block on the urethral sphincter and bladder during SARS and the recovery time were monitored by urodynamic investigation. A complete cold block of the urethral sphincter during spinal nerve cooling was achieved in all cases. During pudendal nerve cooling, the sphincter was completely blocked in two, and incompletely blocked in four dogs. Cold block temperature of the spinal nerves averaged +11.7C and of the pudendal nerves +6.2C. During SARS and spinal nerve cooling, an increase in intravesical pressure up to 13 cm. water was recognized, and recovery time was on average 6.6 minutes. Intravesical pressure remained unchanged during pudendal nerve cooling, with recovery time being less than 1 minute. The cold block was always reversible. Cryotechnique is an excellent method for selective and reversible block of the urethral sphincter during SARS to avoid detrusor-sphincter-dyssynergia. The application of cryotechnique in functional electrical stimulation leads to an improvement of quality of life in para- or tetraplegic patients because of selective nerve stimulation with optimization of micturition, standing, walking and grasping and does so without the necessity of surgical dorsal root rhizotomy.

SKLB060 Reversibly Binds to Colchicine Site of Tubulin and Possesses Efficacy in Multidrug-Resistant Cell Lines.

PubMed

Yan, Wei; Yang, Tao; Yang, Jianhong; Wang, Taijin; Yu, Yamei; Wang, Yuxi; Chen, Qiang; Bai, Peng; Li, Dan; Ye, Haoyu; Qiu, Qiang; Zhou, Yongzhao; Hu, Yiguo; Yang, Shengyong; Wei, Yuquan; Li, Weimin; Chen, Lijuan

2018-05-22

Many tubulin inhibitors are in clinical use as anti-cancer drugs. In our previous study, a novel series of 4-substituted coumarins derivatives were identified as novel tubulin inhibitors. Here, we report the anti-cancer activity and underlying mechanism of one of the 4-substituted coumarins derivatives (SKLB060). The anti-cancer activity of SKLB060 was tested on 13 different cancer cell lines and four xenograft cancer models. Immunofluorescence staining, cell cycle analysis, and tubulin polymerization assay were employed to study the inhibition of tubulin. N, N '-Ethylenebis(iodoacetamide) assay was used to measure binding to the colchicine site. Wound-healing migration and tube formation assays were performed on human umbilical vascular endothelial cells to study anti-vascular activity (the ability to inhibit blood vessel growth). Mitotic block reversibility and structural biology assays were used to investigate the SKLB060-tubulin bound model. SKLB060 inhibited tubulin polymerization and subsequently induced G2/M cell cycle arrest and apoptosis in cancer cells. SKLB060 bound to the colchicine site of β-tubulin and showed antivascular activity in vitro. Moreover, SKLB060 induced reversible cell cycle arrest and reversible inhibition of tubulin polymerization. A mitotic block reversibility assay showed that the effects of SKLB060 have greater reversibility than those of colcemid (a reversible tubulin inhibitor), indicating that SKLB060 binds to tubulin in a totally reversible manner. The crystal structures of SKLB060-tubulin complexes confirmed that SKLB060 binds to the colchicine site, and the natural coumarin ring in SKLB060 enables reversible binding. These results reveal that SKLB060 is a powerful and reversible microtubule inhibitor that binds to the colchicine site and is effective in multidrug-resistant cell lines. © 2018 The Author(s). Published by S. Karger AG, Basel.

Synthesis, characterization, conformation and self-assembly behavior of polypeptide-based brush with oligo (ethylene glycol) side chains

NASA Astrophysics Data System (ADS)

Huang, Yugang; Luo, Weiang; Ye, Guodong

2015-02-01

A new polypeptide-based copolymer brush composed of poly (γ-propargyl-L-glutamate)-block-poly (propylene oxide)-block-poly (γ-propargyl-L-glutamate) backbone (PPLG-b-PPO-b-PPLG) and oligo (ethylene glycol) (PEG) side-chain was synthesized by combination of N-carboxyanhydride ring-opening polymerization and click chemistry. Nearly 100% grafting efficiency was achieved by copper-catalyzed azide-alkyne Huisgen 1,3-dipolar cycloaddition (CuAAc) reaction. The α-helical conformation adopted by the grafted polypeptide blocks in water was relatively stable and showed a reversible change in a heating-cooling circle from 5 to 70 °C. It displayed weak stability against elevated temperature but still reversible changes in the presence of 0.47 M NaCl. The brushes were amphiphilic and could self-assemble into thermo-sensitive micelles in water. Big micelles could break into small micelles upon heating due to the improved solubility.

Simulation design of uniform low turn-on voltage and high reverse blocking AlGaN/GaN power field effect rectifier with trench heterojunction anode

NASA Astrophysics Data System (ADS)

Wang, Fangzhou; Chen, Wanjun; Wang, Zeheng; Sun, Ruize; Wei, Jin; Li, Xuan; Shi, Yijun; Jin, Xiaosheng; Xu, Xiaorui; Chen, Nan; Zhou, Qi; Zhang, Bo

2017-05-01

To achieve uniform low turn-on voltage and high reverse blocking capability, an AlGaN/GaN power field effect rectifier with trench heterojunction anode (THA-FER) is proposed and investigated in this work which includes only simulated data and no real experimental result. VT has a low saturation value when trench height (HT) is beyond 300 nm, confirming it is possible to control the VT accurately without precisely controlling the HT in the THA-FER. Meanwhile, high HT anode reduces reverse leakage current and yields high breakdown voltage (VB). A superior high Baliga's Figure of Merits (BFOM = VB2/Ron,sp, Ron,sp is specific-on resistance) of 1228 MW/cm2 reveals the THA-FER caters for the demands of high efficiency GaN power applications.

North-South contraction of the mojave block and strike-slip tectonics in southern california.

PubMed

Bartley, J M; Glazner, A F; Schermer, E R

1990-06-15

The Mojave block of southern California has undergone significant late Cenozoic north-south contraction. This previously unappreciated deformation may account for part of the discrepancy between neotectonic and plate-tectonic estimates of Pacific-North American plate motion, and for part of the Big Bend in the San Andreas fault. In the eastern Mojave block, contraction is superimposed on early Miocene crustal extension. In the western Mojave block, contractional folds and reverse faults have been mistaken for extensional structures. The three-dimensional complexity of the contractional structures may mean that rigid-block tectonic models of the region based primarily on paleomagnetic data are unreliable.

Temperature characteristics and magnetization mechanism of Fe1.2Co films

NASA Astrophysics Data System (ADS)

Dong, Dashun; Fang, Qingqing; Wang, Wenwen; Yang, Jingjing

2017-11-01

Fe1.2Co films with various thicknesses were prepared on glass substrates by pulsed laser deposition (PLD). The Fe1.2Co crystal structure exhibited a preferred orientation in the <1 1 0> direction. Also, we found that changing the film thickness affected its magnetic properties and the formation of its reversed nucleus. By measuring magnetism-temperature (M-T) curves under applied field cooling (FC) and zero-field cooling (ZFC), we found that the mechanism of the formation and growth of the reversed nucleus played a main role in blocking the motion of domain walls: the mechanism was competition between a ferromagnetic phase (FM) and an anti-ferromagnetic phase (AFM) at 10-300 K. Moreover, we found that the reversed nucleus blocked the motion of magnetic domains more at 10 K than at 300 K. We suggest that the reversed nucleus affects the magnetism more at low temperatures, which causes the coercivity to be higher at low temperature than at room temperature. These results will help us to understand the magnetic properties and temperature characteristics of FeCo thin films.

pH-sensitive multi-PEGylated block copolymer as a bioresponsive pDNA delivery vector.

PubMed

Lai, Tsz Chung; Bae, Younsoo; Yoshida, Takayuki; Kataoka, Kazunori; Kwon, Glen S

2010-11-01

A reversibly-PEGylated diblock copolymer, poly(aspartate-hydrazide-poly(ethylene glycol))-block-poly(aspartate-diaminoethane) (p[Asp(Hyd-PEG)]-b-p[Asp(DET)]) was reported here for enhanced gene transfection and colloidal stability. The diblock copolymer possessed a unique architecture based on a poly(aspartamide) backbone. The first block, p[Asp(Hyd)], was used for multi-PEG conjugations, and the second block, p[Asp(DET)], was used for DNA condensation and endosomal escape. p[Asp(Hyd-PEG)]-b-p[Asp(DET)] was synthesized and characterized by (1)H-NMR. Polyplexes were formed by mixing the synthesized polymers and pDNA. The polyplex size, ζ-potential, and in vitro transfection efficiency were determined by dynamic light scattering, ζ-potential measurements, and luciferase assays, respectively. pH-dependent release of PEG from the polymer was monitored by cationic-exchange chromatography. The polyplexes were 70-90 nm in size, and the surface charge was effectively shielded by a PEG layer. The transfection efficiency of the reversibly PEGylated polyplexes was confirmed to be comparable to that of the non-PEGylated counterparts and 1,000 times higher than that of the irreversibly PEGylated polyplexes. PEG release was demonstrated to be pH-sensitive. Fifty percent of the PEG was released within 30 min at pH 5, while the polymer incubated at pH 7.4 could still maintain 50% of PEG after 8 h. The reversibly PEGylated polyplexes were shown to maintain polyplex stability without compromising transfection efficiency.

Long Range Spoil Disposal Study. Part 3. Sub-Study 2. Nature, Source, and Cause of Shoal

DTIC Science & Technology

1973-09-01

Report) Prepared for public release; distribution unlimited 17. DISTRIBUTION STATEMENT (of the abetract entered In Block 20, if different from Report) IS...SUPPLEMENTARY NOTES 19. KEY WORDS (Continue on reverse side if necseseey and identify by block number) Delaware River River Channel Delaware Estuary...Marcus Hook, Pa. Dredging Hydraulic Dredge Spoil Disposal Sediment transport 2o ABSTRACT r -ciftue a r verse - i- - n a eay amd ideai fy by block

Interspecies Extrapolations of Halocarbon Respiratory and Tissue Kinetics: Applications to Predicting Toxicity in Different Species.

DTIC Science & Technology

1992-09-04

Nfl~V~ AOI~OVI]DQE V~C SV: ONG0d~ (O I Fig. E-9 IL 00 -. Q 0) S70) a0) c(n 0 L 0 U0 LO >0 U 0 0~ N 0000 * Li ) Ci ) I 𔃺~L -:5 M T.- 0) 7r00 y \\ 0C Y ...depression, toxico - md 19. ABSTRACT (Continue on reverse if necessary and identify by block number) A series of experiments have been conducted to...1800 x g for 10 min. A lO -ul aliquot of the supernatant was transferred into a headspace vial and capped with an aluminum cap and PTFE-lined septum

Septal and Anterior Reverse Mismatch of Myocardial Perfusion and Metabolism in Patients With Coronary Artery Disease and Left Bundle Branch Block

PubMed Central

Wang, Jian-Guang; Fang, Wei; Yang, Min-Fu; Tian, Yue-Qin; Zhang, Xiao-Li; Shen, Rui; Sun, Xiao-Xin; Guo, Feng; Wang, Dao-Yu; He, Zuo-Xiang

2015-01-01

Abstract The effects of left bundle branch block (LBBB) on left ventricular myocardial metabolism have not been well investigated. This study evaluated these effects in patients with coronary artery disease (CAD). Sixty-five CAD patients with complete LBBB (mean age, 61.8 ± 9.7 years) and 65 without LBBB (mean age, 59.9 ± 8.4 years) underwent single photon emission computed tomography, positron emission tomography, and contrast coronary angiography. The relationship between myocardial perfusion and metabolism and reverse mismatch score, and that between QRS length and reverse mismatch score and wall motion score were evaluated. The incidence of left ventricular septum and anterior wall reverse mismatching between the two groups was significantly different (P < 0.001 and P = 0.002, respectively). The incidences of normal myocardial perfusion and metabolism in the left ventricular lateral and inferior walls were also significantly different between the two groups (P < 0.001 and P < 0.001, respectively). The incidence of septal reverse mismatching in patients with mild to moderate perfusion was significantly higher among those with LBBB than among those without LBBB (P < 0.001). In CAD patients with LBBB, septal reverse mismatching was significantly more common among those with mild to moderate perfusion than among those with severe perfusion defects (P = 0.002). The correlation between the septal reverse mismatch score and QRS length was significant (P = 0.026). In patients with CAD and LBBB, septal and anterior reverse mismatching of myocardial perfusion and metabolism was frequently present; the septal reverse mismatch score negatively correlated with the QRS interval. PMID:25997045

Temporary persistence of conduction block after prolonged kilohertz frequency alternating current on rat sciatic nerve

NASA Astrophysics Data System (ADS)

Bhadra, Narendra; Foldes, Emily; Vrabec, Tina; Kilgore, Kevin; Bhadra, Niloy

2018-02-01

Objective. Application of kilohertz frequency alternating current (KHFAC) waveforms can result in nerve conduction block that is induced in less than a second. Conduction recovers within seconds when KHFAC is applied for about 5-10 min. This study investigated the effect of repeated and prolonged application of KHFAC on rat sciatic nerve with bipolar platinum electrodes. Approach. Varying durations of KHFAC at signal amplitudes for conduction block with intervals of no stimulus were studied. Nerve conduction was monitored by recording peak Gastrocnemius muscle force utilizing stimulation electrodes proximal (PS) and distal (DS) to a blocking electrode. The PS signal traveled through the block zone on the nerve, while the DS went directly to the motor end-plate junction. The PS/DS force ratio provided a measure of conduction patency of the nerve in the block zone. Main results. Conduction recovery times were found to be significantly affected by the cumulative duration of KHFAC application. Peak stimulated muscle force returned to pre-block levels immediately after cessation of KHFAC delivery when it was applied for less than about 15 min. They fell significantly but recovered to near pre-block levels for cumulative stimulus of 50  ±  20 min, for the tested On/Off times and frequencies. Conduction recovered in two phases, an initial fast one (60-80% recovery), followed by a slower phase. No permanent conduction block was seen at the end of the observation period during any experiment. Significance. This carry-over block effect may be exploited to provide continuous conduction block in peripheral nerves without continuous application of KHFAC.

A human intermediate conductance calcium-activated potassium channel.

PubMed

Ishii, T M; Silvia, C; Hirschberg, B; Bond, C T; Adelman, J P; Maylie, J

1997-10-14

An intermediate conductance calcium-activated potassium channel, hIK1, was cloned from human pancreas. The predicted amino acid sequence is related to, but distinct from, the small conductance calcium-activated potassium channel subfamily, which is approximately 50% conserved. hIK1 mRNA was detected in peripheral tissues but not in brain. Expression of hIK1 in Xenopus oocytes gave rise to inwardly rectifying potassium currents, which were activated by submicromolar concentrations of intracellular calcium (K0.5 = 0.3 microM). Although the K0.5 for calcium was similar to that of small conductance calcium-activated potassium channels, the slope factor derived from the Hill equation was significantly reduced (1.7 vs. 3. 5). Single-channel current amplitudes reflected the macroscopic inward rectification and revealed a conductance level of 39 pS in the inward direction. hIK1 currents were reversibly blocked by charybdotoxin (Ki = 2.5 nM) and clotrimazole (Ki = 24.8 nM) but were minimally affected by apamin (100 nM), iberiotoxin (50 nM), or ketoconazole (10 microM). These biophysical and pharmacological properties are consistent with native intermediate conductance calcium-activated potassium channels, including the erythrocyte Gardos channel.

A human intermediate conductance calcium-activated potassium channel

PubMed Central

Ishii, Takahiro M.; Silvia, Christopher; Hirschberg, Birgit; Bond, Chris T.; Adelman, John P.; Maylie, James

1997-01-01

An intermediate conductance calcium-activated potassium channel, hIK1, was cloned from human pancreas. The predicted amino acid sequence is related to, but distinct from, the small conductance calcium-activated potassium channel subfamily, which is ≈50% conserved. hIK1 mRNA was detected in peripheral tissues but not in brain. Expression of hIK1 in Xenopus oocytes gave rise to inwardly rectifying potassium currents, which were activated by submicromolar concentrations of intracellular calcium (K0.5 = 0.3 μM). Although the K0.5 for calcium was similar to that of small conductance calcium-activated potassium channels, the slope factor derived from the Hill equation was significantly reduced (1.7 vs. 3.5). Single-channel current amplitudes reflected the macroscopic inward rectification and revealed a conductance level of 39 pS in the inward direction. hIK1 currents were reversibly blocked by charybdotoxin (Ki = 2.5 nM) and clotrimazole (Ki = 24.8 nM) but were minimally affected by apamin (100 nM), iberiotoxin (50 nM), or ketoconazole (10 μM). These biophysical and pharmacological properties are consistent with native intermediate conductance calcium-activated potassium channels, including the erythrocyte Gardos channel. PMID:9326665

The effect of routine reversal of neuromuscular blockade on adequacy of recurrent laryngeal nerve stimulation during thyroid surgery.

PubMed

Marshall, S D; Boden, E; Serpell, J

2015-07-01

Testing of the integrity of the recurrent laryngeal nerve during thyroid surgery has become routine practice for many surgeons to aid dissection and minimise the chance of inadvertent nerve injury. We hypothesised that routine reversal of an intermediate-acting, non-depolarising neuromuscular blocking agent would improve conditions for stimulation of the recurrent laryngeal nerve. We conducted a single-centre, randomised, double-blind placebo-controlled trial of patients undergoing thyroid surgery by the same surgeon. After randomisation, the participants received either neostigmine 2.5 mg with glycopyrrolate 0.4 mg or placebo, at 30 minutes after induction of anaesthesia and administration of 0.4 mg/kg of atracurium. The primary outcome was the subjective assessment by the surgeon as to whether the neuromuscular function was adequate for stimulation of the recurrent laryngeal nerve using a neuromuscular integrity monitor (NIM). Time to NIM stimulation was 44.6 minutes in the placebo group and 41.4 minutes in the intervention group (P=0.268). Of the 21 patients who received the neuromuscular blockade reversal, 20 (95.2%) had adequate surgical conditions for NIM stimulation, compared to 9 out of 18 patients (50%) in the placebo group (P=0.002). Three of the ten patients (30%) with inadequate reversal showed no evidence of residual blockade assessed peripherally. The routine reversal of neuromuscular blockade at 30 minutes post induction appears to result in adequate surgical conditions for safe stimulation of the recurrent laryngeal nerve. Return of neuromuscular function at a peripheral site does not guarantee adequate laryngeal muscle function for use of the NIM.

Organic photovoltaic cell incorporating electron conducting exciton blocking layers

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

Forrest, Stephen R.; Lassiter, Brian E.

2014-08-26

The present disclosure relates to photosensitive optoelectronic devices including a compound blocking layer located between an acceptor material and a cathode, the compound blocking layer including: at least one electron conducting material, and at least one wide-gap electron conducting exciton blocking layer. For example, 3,4,9,10 perylenetetracarboxylic bisbenzimidazole (PTCBI) and 1,4,5,8-napthalene-tetracarboxylic-dianhydride (NTCDA) function as electron conducting and exciton blocking layers when interposed between the acceptor layer and cathode. Both materials serve as efficient electron conductors, leading to a fill factor as high as 0.70. By using an NTCDA/PTCBI compound blocking layer structure increased power conversion efficiency is achieved, compared to anmore » analogous device using a conventional blocking layers shown to conduct electrons via damage-induced midgap states.« less

In Vitro Cross-Resistance Profiles of Rilpivirine, Dapivirine, and MIV-150, Nonnucleoside Reverse Transcriptase Inhibitor Microbicides in Clinical Development for the Prevention of HIV-1 Infection

PubMed Central

Giacobbi, Nicholas S.

2017-01-01

ABSTRACT Rilpivirine (RPV), dapivirine (DPV), and MIV-150 are in development as microbicides. It is not known whether they will block infection of circulating nonnucleoside reverse transcriptase inhibitor (NNRTI)-resistant human immunodeficiency virus type 1 (HIV-1) variants. Here, we demonstrate that the activity of DPV and MIV-150 is compromised by many resistant viruses containing single or double substitutions. High DPV genital tract concentrations from DPV ring use may block replication of resistant viruses. However, MIV-150 genital tract concentrations may be insufficient to inhibit many resistant viruses, including those harboring K103N or Y181C. PMID:28507107

The effects of catecholamines and adrenoceptor blocking drugs on the canine peripheral lymph flow.

PubMed Central

De Micheli, P; Glässer, A H

1975-01-01

Blood flow through the femoral artery, lymph flow in a lymphatic vessel in the femoral triangle and metatarsal distal venous pressure were measured simultaneously in a canine moving hind limb. 2. Low intra-arterial doses of adrenaline and noradrenaline increased lymph flow even in the presence of marked arterial vasoconstriction. In contrast, isoprenaline increased arterial blood flow without affecting lymph flow rate. 3. Phenoxybenzamine, dihydroergotoxine, and nicergoline did not inhibit the lymphatic flow increase induced by adrenaline at doses active on arterial or venous vascular alpha-adrenoceptors. 4. Propranolol given intra-arterially into animals pretreated with alpha-adrenoceptor blocking agents restored the vasoconstrictor effect of adrenaline (reversal of adrenaline reversal). PMID:238702

Reversible modulation of the redox activity in conducting polymer nanofilms induced by hydrophobic collapse of a surface-grafted polyelectrolyte.

PubMed

Fenoy, Gonzalo E; Giussi, Juan M; von Bilderling, Catalina; Maza, Eliana M; Pietrasanta, Lía I; Knoll, Wolfgang; Marmisollé, Waldemar A; Azzaroni, Omar

2018-05-15

We present the covalent modification of a Pani-like conducting polymer (polyaminobenzylamine, PABA) by grafting of a polyelectrolyte brush (poly [2-(methacryloyloxy)-ethyl-trimethylammonium chloride], PMETAC). As PABA has extra pendant amino moieties, the grafting procedure does not affect the backbone nitrogen atoms that are implicated in the electronic structure of the conducting polymers. Moreover, perchlorate anions interact very strongly with the quaternary ammonium pendant groups of PMETAC through ion pairing. Therefore, the grafting does not only keep the electroactivity of PABA in aqueous solutions but it adds the ion-actuation properties of the PMETAC brush to the modified electrode as demonstrated by contact angle measurements and electrochemical methods. In this way, the conjugation of the electron transfer properties of the conducting polymer with the anion responsiveness of the integrated brush renders perchlorate actuation of the electrochemical response. These results constitute a rational integration of nanometer-sized polymer building blocks that yields synergism of functionalities and illustrate the potentialities of nanoarchitectonics for pushing the limits of soft material science into the nanoworld. Copyright © 2018 Elsevier Inc. All rights reserved.

Self-assembly of block copolymer micelles: synthesis via reversible addition-fragmentation chain transfer polymerization and aqueous solution properties.

PubMed

Mya, Khine Y; Lin, Esther M J; Gudipati, Chakravarthy S; Gose, Halima B A S; He, Chaobin

2010-07-22

Poly(hexafluorobutyl methacrylate) (PHFBMA) homopolymer was synthesized by reversible addition-fragmentation chain transfer (RAFT)-mediated living radical polymerization in the presence of cyano-2-propyl dithiobenzoate (CPDB) RAFT agent. A block copolymer of PHFBMA-poly(propylene glycol acrylate) (PHFBMA-b-PPGA) with dangling poly(propylene glycol) (PPG) side chains was then synthesized by using CPDB-terminated PHFBMA as a macro-RAFT agent. The amphiphilic properties and self-assembly of PHFBMA-b-PPGA block copolymer in aqueous solution were investigated by dynamic and static light scattering (DLS and SLS) studies, in combination with fluorescence spectroscopy and transmission electron microscopy (TEM). Although PPG shows moderately hydrophilic character, the formation of nanosize polymeric micelles was confirmed by fluorescence and TEM studies. The low value of the critical aggregation concentration exhibited that the tendency for the formation of copolymer aggregates in aqueous solution was very high due to the strong hydrophobicity of the PHFBMA(145)-b-PPGA(33) block copolymer. The combination of DLS and SLS measurements revealed the existence of micellar aggregates in aqueous solution with an association number of approximately 40 +/- 7 for block copolymer micelles. It was also found in TEM observation that there are 40-50 micelles accumulated into one aggregate and these micelles are loosely packed inside the aggregate.

Single channel analysis of the blocking actions of BIDN and fipronil on a Drosophila melanogaster GABA receptor (RDL) stably expressed in a Drosophila cell line

PubMed Central

Grolleau, Françoise; Sattelle, David B

2000-01-01

Single channel recordings were obtained from a Drosophila S2 cell line stably expressing the wild-type RDLac Drosophila melanogaster homomer-forming ionotropic GABA receptor subunit, a product of the resistance to dieldrin gene, Rdl. GABA (50 μM) was applied by pressure ejection to outside-out patches from S2-RDL cells at a holding potential of −60 mV. The resulting inward current was completely blocked by 100 μM picrotoxin (PTX). The unitary current-voltage relationship was linear at negative potentials but showed slight inward rectification at potentials more positive than 0 mV. The reversal potential of the current (EGABA=−1.4 mV) was close to the calculated chloride equilibrium potential. The single channel conductance elicited by GABA was 36 pS. A 71 pS conductance channel was also observed when the duration of the pulse, used to eject GABA, was longer than 80 ms. The mean open time distribution of the unitary events was fitted best by two exponential functions suggesting two open channel states. When either 1 μM fipronil or 1 μM BIDN was present in the external saline, the GABA-gated channels were completely blocked. When BIDN or fipronil was applied at a concentration close to the IC50 value for suppression of open probability (281 nM, BIDN; 240 nM, fipronil), the duration of channel openings was shortened. In addition, the blocking action of BIDN resulted in the appearance of a novel channel conductance (17 pS). The effects of co-application of BIDN and fipronil were examined. Co-application of BIDN (300 nM) with various concentrations (100–1000 nM) of fipronil resulted in an additional BIDN-induced dose-dependent reduction of the maximum Po value. Thus both BIDN and fipronil shorten the duration of wild-type RDLac GABA receptor channel openings but appear to act at distinct sites. PMID:10952672

Optical reversible programmable Boolean logic unit.

PubMed

Chattopadhyay, Tanay

2012-07-20

Computing with reversibility is the only way to avoid dissipation of energy associated with bit erase. So, a reversible microprocessor is required for future computing. In this paper, a design of a simple all-optical reversible programmable processor is proposed using a polarizing beam splitter, liquid crystal-phase spatial light modulators, a half-wave plate, and plane mirrors. This circuit can perform 16 logical operations according to three programming inputs. Also, inputs can be easily recovered from the outputs. It is named the "reversible programmable Boolean logic unit (RPBLU)." The logic unit is the basic building block of many complex computational operations. Hence the design is important in sense. Two orthogonally polarized lights are defined here as two logical states, respectively.

Polybenzimidazole block copolymers for fuel cell: synthesis and studies of block length effects on nanophase separation, mechanical properties, and proton conductivity of PEM.

PubMed

Maity, Sudhangshu; Jana, Tushar

2014-05-14

A series of meta-polybenzimidazole-block-para-polybenzimidazole (m-PBI-b-p-PBI), segmented block copolymers of PBI, were synthesized with various structural motifs and block lengths by condensing the diamine terminated meta-PBI (m-PBI-Am) and acid terminated para-PBI (p-PBI-Ac) oligomers. NMR studies and existence of two distinct glass transition temperatures (Tg), obtained from dynamical mechanical analysis (DMA) results, unequivocally confirmed the formation of block copolymer structure through the current polymerization methodology. Appropriate and careful selection of oligomers chain length enabled us to tailor the block length of block copolymers and also to make varieties of structural motifs. Increasingly distinct Tg peaks with higher block length of segmented block structure attributed the decrease in phase mixing between the meta-PBI and para-PBI blocks, which in turn resulted into nanophase segregated domains. The proton conductivities of proton exchange membrane (PEM) developed from phosphoric acid (PA) doped block copolymer membranes were found to be increasing substantially with increasing block length of copolymers even though PA loading of these membranes did not alter appreciably with varying block length. For example when molecular weight (Mn) of blocks were increased from 1000 to 5500 then the proton conductivities at 160 °C of resulting copolymers increased from 0.05 to 0.11 S/cm. Higher block length induced nanophase separation between the blocks by creating less morphological barrier within the block which facilitated the movement of the proton in the block and hence resulting higher proton conductivity of the PEM. The structural varieties also influenced the phase separation and proton conductivity. In comparison to meta-para random copolymers reported earlier, the current meta-para segmented block copolymers were found to be more suitable for PBI-based PEM.

Sugammadex and neostigmine dose-finding study for reversal of residual neuromuscular block at a train-of-four ratio of 0.2 (SUNDRO20)†,.

PubMed

Kaufhold, N; Schaller, S J; Stäuble, C G; Baumüller, E; Ulm, K; Blobner, M; Fink, H

2016-02-01

The aim of this dose-finding study was to evaluate the dose-response relationship of sugammadex and neostigmine to reverse a commonly observed level of incomplete recovery from rocuronium-induced neuromuscular block, that is, a train-of-four ratio (TOFR) ≥0.2. Ninety-nine anaesthetized patients received rocuronium 0.6 mg kg(-1) i.v. for tracheal intubation and, if necessary, incremental doses of 0.1-0.2 mg kg(-1). Neuromuscular monitoring was performed by calibrated electromyography. Once the TOFR recovered to 0.2, patients were randomized to receive sugammadex (0.25, 0.5, 0.75, 1.0, or 1.25 mg kg(-1) i.v.), neostigmine (10, 25, 40, 55, or 70 µg kg(-1) i.v.), or saline (n=9 per group). Primary and secondary end points were the doses necessary to restore neuromuscular function to a TOFR≥0.9 with an upper limit of 5 and 10 min for 95% of patients, respectively. Neostigmine was not able to fulfil the end points. Based on the best-fitting model, the sugammadex dose estimation for recovery to a TOFR≥0.9 for 95% of patients within 5 and 10 min was 0.49 and 0.26 mg kg(-1), respectively. A residual neuromuscular block of a TOFR of 0.2 cannot be reversed reliably with neostigmine within 10 min. In the conditions studied, substantially lower doses of sugammadex than the approved dose of 2.0 mg kg(-1) may be sufficient to reverse residual rocuronium-induced neuromuscular block at a recovery of TOFR≥0.2. NCT01006720. © The Author 2016. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Change in the temporal coordination of the finger joints with ulnar nerve block during different power grips analyzed with a sensor glove.

PubMed

Wachter, N J; Mentzel, M; Häderer, C; Krischak, G D; Gülke, J

2018-02-01

Ulnar nerve injuries can cause deficient hand movement patterns. Their assessment is important for diagnosis and rehabilitation in hand surgery cases. The purpose of this study was to quantify the changes in temporal coordination of the finger joints during different power grips with an ulnar nerve block by means of a sensor glove. In 21 healthy subjects, the onset and end of the active flexion of the 14 finger joints when gripping objects of different diameters was recorded by a sensor glove. The measurement was repeated after an ulnar nerve block was applied in a standardized setting. The change in the temporal coordination of the metacarpophalangeal (MCP), proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints with and without the nerve block was calculated within the same subject. In healthy subjects, the MCP joints started their movement prior to the PIP joints in the middle and ring finger, whereas this occurred in the reverse order at the index and little finger. The DIP joint onset was significantly delayed (P<0.01). With the ulnar nerve block, this coordination shifted towards simultaneous onset of all joints, independent of the grip diameter. The thumb and index finger were affected the least. With an ulnar nerve block, the PIP joints completed their movement prior to the MCP joints when gripping small objects (G1 and G2), whereas the order was reversed with larger objects (G3 and G4). The alterations with ulnar nerve block affected mainly the little finger when gripping small objects. With larger diameter objects, all fingers had a significant delay at the end of the PIP joint movement relative to the MCP and DIP joints, and the PIP and DIP joint sequence was reversed (P<0.01). Based on the significant changes in temporal coordination of finger flexion during different power grips, there are biomechanical effects of loss of function of the intrinsic muscles caused by an ulnar nerve block on the fine motor skills of the hand. This can be important for the diagnosis and rehabilitation of ulnar nerve lesions of the hand. Copyright © 2017 SFCM. Published by Elsevier Masson SAS. All rights reserved.

Paleomagnetic quantification of upper-plate deformation during Miocene detachment faulting in the Mohave Mountains, Arizona

USGS Publications Warehouse

Pease, V.; Hillhouse, J.W.; Wells, R.E.

2005-01-01

Paleomagnetic data from Miocene (???20 Ma) volcanic rocks and dikes of west central Arizona reveal the tilt history of Proterozoic crystalline rocks in the hanging wall of the Chemehuevi-Whipple Mountains detachment fault. We obtained magnetization data from dikes and flows in two structural blocks encompassing Crossman Peak and Standard Wash in the Mohave Mountains. In the Crossman block the dike swarm records two components of primary magnetization: (1) CNH, a normal polarity, high-unblocking-temperature or high-coercivity component (inclination, I = 48.5??, declination, D = 6.4??), and (2) CRHm, a reversed polarity, high-temperature or high-coercivity component (I = -33.6??, D = 197.5??). Argon age spectra imply that the dikes have not been reheated above 300??C since their emplacement, and a baked-contact test suggests that the magnetization is likely to be Miocene in age. CRHm deviates from the expected direction of the Miocene axial dipole field and is best explained as a result of progressive tilting about the strike of the overlying andesite flows. These data suggest that the Crossman block was tilted 60?? to the southwest prior to intrusion of the vertical dike swarm, and the block continued to tilt during a magnetic field reversal to normal polarity (CNH). Miocene dikes in the Crossman block are roughly coplanar, so the younger dikes with normal polarity magnetization intruded along planes of weakness parallel to the earlier reversed polarity swarm. An alternative explanation involves CNH magnetization being acquired later during hydrothermal alteration associated with the final stages of dike emplacement. In the Standard Wash block, the primary component of magnetization is a dual-polarity, high-temperature or high-coercivity component (SWHl, I = 7.2??,D= 0.7??). To produce agreement between the expected Miocene magnetic direction and the SWH component requires (1) correcting for a 56?? tilt about the strike of flow bedding and (2) removing a counterclockwise vertical-axis rotation of 20??. The two rotations restore the Standard Wash dikes to vertical, make parallel the dike layering in the Crossman and Standard Wash blocks, and align the strikes of bedding in both blocks. Geologic mapping, geochemical evidence, and paleomagnetic data are consistent with the upper plate of the Mohave Mountains having tilted in response to formation of the underlying detachment fault.

Light-enabled reversible self-assembly and tunable optical properties of stable hairy nanoparticles

NASA Astrophysics Data System (ADS)

Chen, Yihuang; Wang, Zewei; He, Yanjie; Yoon, Young Jun; Jung, Jaehan; Zhang, Guangzhao; Lin, Zhiqun

2018-02-01

The ability to dynamically organize functional nanoparticles (NPs) via the use of environmental triggers (temperature, pH, light, or solvent polarity) opens up important perspectives for rapid and convenient construction of a rich variety of complex assemblies and materials with new structures and functionalities. Here, we report an unconventional strategy for crafting stable hairy NPs with light-enabled reversible and reliable self-assembly and tunable optical properties. Central to our strategy is to judiciously design amphiphilic star-like diblock copolymers comprising inner hydrophilic blocks and outer hydrophobic photoresponsive blocks as nanoreactors to direct the synthesis of monodisperse plasmonic NPs intimately and permanently capped with photoresponsive polymers. The size and shape of hairy NPs can be precisely tailored by modulating the length of inner hydrophilic block of star-like diblock copolymers. The perpetual anchoring of photoresponsive polymers on the NP surface renders the attractive feature of self-assembly and disassembly of NPs on demand using light of different wavelengths, as revealed by tunable surface plasmon resonance absorption of NPs and the reversible transformation of NPs between their dispersed and aggregated states. The dye encapsulation/release studies manifested that such photoresponsive NPs may be exploited as smart guest molecule nanocarriers. By extension, the star-like block copolymer strategy enables the crafting of a family of stable stimuli-responsive NPs (e.g., temperature- or pH-sensitive polymer-capped magnetic, ferroelectric, upconversion, or semiconducting NPs) and their assemblies for fundamental research in self-assembly and crystallization kinetics of NPs as well as potential applications in optics, optoelectronics, magnetic technologies, sensory materials and devices, catalysis, nanotechnology, and biotechnology.

Sugammadex for reversal of neuromuscular block after rapid sequence intubation: a systematic review and economic assessment†

PubMed Central

Chambers, D.; Paulden, M.; Paton, F.; Heirs, M.; Duffy, S.; Hunter, J. M.; Sculpher, M.; Woolacott, N.

2010-01-01

Summary Sugammadex 16 mg kg−1 can be used for the immediate reversal of neuromuscular block 3 min after administration of rocuronium and could be used in place of succinylcholine for emergency intubation. We have systematically reviewed the efficacy and cost-effectiveness and made an economic assessment of sugammadex for immediate reversal. The economic assessment investigated whether sugammadex appears cost-effective under various assumptions about the value of any reduction in recovery time with sugammadex, the likelihood of a ‘can't intubate, can't ventilate’ (CICV) event, the age of the patient, and the length of the procedure. Three trials were included in the efficacy review. Sugammadex administered 3 or 5 min after rocuronium produced markedly faster recovery than placebo or spontaneous recovery from succinylcholine-induced block. No published economic evaluations were found. Our economic analyses showed that sugammadex appears more cost-effective, where the value of any reduction in recovery time is greater, where the reduction in mortality compared with succinylcholine is greater, and where the patient is younger, for lower probabilities of a CICV event and for long procedures which do not require profound block throughout. Because of the lack of evidence, the value of some parameters remains unknown, which makes it difficult to provide a definitive assessment of the cost-effectiveness of sugammadex in practice. The use of sugammadex in combination with high-dose rocuronium is efficacious. Further research is needed to clarify key parameters in the analysis and to allow a fuller economic assessment. PMID:20937718

Synthesis of carboxylic block copolymers via reversible addition fragmentation transfer polymerization for tooth erosion prevention.

PubMed

Lei, Y; Wang, T; Mitchell, J W; Qiu, J; Kilpatrick-Liverman, L

2014-12-01

Dental professionals are seeing a growing population of patients with visible signs of dental erosion. The approach currently being used to address the problem typically leverages the enamel protection benefits of fluoride. In this report, an alternative new block copolymer with a hydrophilic polyacrylic acid (PAA) block and a hydrophobic poly(methyl methacrylate) (PMMA) block was developed to similarly reduce the mineral loss from enamel under acidic conditions. This series of PMMA-b-PAA block copolymers was synthesized by reversible addition fragmentation transfer (RAFT) polymerization. Their structures were characterized by gel permeation chromatography (GPC) and (1)H nuclear magnetic resonance (NMR) spectra. The molar fractions of acrylic acid (AA) in the final block copolymer were finely controlled from 0.25 to 0.94, and the molecular weight (Mn) of PMMA-b-PAA was controlled from 10 kDa to 90 kDa. The binding capability of the block copolymer with hydroxyapatite (HAP) was investigated by ultraviolet-visible spectroscopy (UV-Vis) and Fourier transform infrared (FTIR) spectroscopy. FTIR spectra confirmed that the PMMA-b-PAA block copolymer could bind to HAP via bridging bidentate bonds. Both UV-Vis and FTIR spectra additionally indicated that a high polymer concentration and low solution pH favored the polymer binding to HAP. The erosion-preventing efficacy of the PMMA-b-PAA block copolymer in inhibiting HAP mineral loss was quantitatively evaluated by atomic absorption spectroscopy (AAS). Based on the results, polymer treatment reduced the amount of calcium released by 27% to 30% in comparison with the unprotected samples. Scanning electron microscope (SEM) observations indicated that PMMA-b-PAA polymer treatment protected enamel from acid erosion. This new amphiphilic block copolymer has significant potential to be integrated into dentifrices or mouthrinses as an alternative non-fluoride ingredient to reduce tooth erosion. © International & American Associations for Dental Research.

Synthesis of Carboxylic Block Copolymers via Reversible Addition Fragmentation Transfer Polymerization for Tooth Erosion Prevention

PubMed Central

Lei, Y.; Wang, T.; Mitchell, J.W.; Qiu, J.; Kilpatrick-Liverman, L.

2014-01-01

Dental professionals are seeing a growing population of patients with visible signs of dental erosion. The approach currently being used to address the problem typically leverages the enamel protection benefits of fluoride. In this report, an alternative new block copolymer with a hydrophilic polyacrylic acid (PAA) block and a hydrophobic poly(methyl methacrylate) (PMMA) block was developed to similarly reduce the mineral loss from enamel under acidic conditions. This series of PMMA-b-PAA block copolymers was synthesized by reversible addition fragmentation transfer (RAFT) polymerization. Their structures were characterized by gel permeation chromatography (GPC) and 1H nuclear magnetic resonance (NMR) spectra. The molar fractions of acrylic acid (AA) in the final block copolymer were finely controlled from 0.25 to 0.94, and the molecular weight (Mn) of PMMA-b-PAA was controlled from 10 kDa to 90 kDa. The binding capability of the block copolymer with hydroxyapatite (HAP) was investigated by ultraviolet–visible spectroscopy (UV-Vis) and Fourier transform infrared (FTIR) spectroscopy. FTIR spectra confirmed that the PMMA-b-PAA block copolymer could bind to HAP via bridging bidentate bonds. Both UV-Vis and FTIR spectra additionally indicated that a high polymer concentration and low solution pH favored the polymer binding to HAP. The erosion-preventing efficacy of the PMMA-b-PAA block copolymer in inhibiting HAP mineral loss was quantitatively evaluated by atomic absorption spectroscopy (AAS). Based on the results, polymer treatment reduced the amount of calcium released by 27% to 30% in comparison with the unprotected samples. Scanning electron microscope (SEM) observations indicated that PMMA-b-PAA polymer treatment protected enamel from acid erosion. This new amphiphilic block copolymer has significant potential to be integrated into dentifrices or mouthrinses as an alternative non-fluoride ingredient to reduce tooth erosion. PMID:25248611

Sugammadex given for rocuronium-induced neuromuscular blockade in infants: a retrospectıve study.

PubMed

Ozmete, Ozlem; Bali, Cagla; Cok, Oya Yalcin; Turk, Hatice Evren Eker; Ozyilkan, Nesrın Bozdogan; Civi, Soner; Aribogan, Anıs

2016-12-01

To evaluate the efficacy and safety of sugammadex in reversing profound neuromuscular block induced by rocuronium in infant patients. Retrospective observational study. University teaching hospital. Twenty-six infants (2-12 months of age; 3-11 kg) with an American Society of Anesthesiologists classification I, II, or III who were scheduled to undergo neurosurgical procedures were included in the study. Anesthesia was induced with 5 mg/kg thiopental, 1 μg/kg fentanyl and 0.6 mg/kg rocuronium. Sevoflurane was administered to all patients after intubation. The neuromuscular block was monitored with acceleromyography using train-of-four (TOF) stimuli. Patients received additional doses of rocuronium to maintain a deep block during surgery. If profound neuromuscular block (TOF, 0) persisted at the end of the surgery, 3mg/kg sugammadex was administered. The demographic data, surgeries, and anesthetic agents were recorded. The time from sugammadex administration to recovery of neuromuscular function (TOF ratio, >0.9) and complications during and after extubation were also recorded. Twenty-six infants who had a deep neuromuscular block (TOF, 0) at the end of surgery received 3 mg/kg sugammadex. The mean recovery time of the T4/T1 ratio of 0.9 was 112 seconds. No clinical evidence of recurarization or residual curarization was observed. The efficacy and safety of sugammadex were confirmed in infant surgical patients for reversal of deep neuromuscular block induced by rocuronium. Copyright © 2016 Elsevier Inc. All rights reserved.

Environmental and Water Quality Operational Studies. Environmental Features for Streambank Protection Projects.

DTIC Science & Technology

1984-11-01

Port Royal Road, Springfield, Virginia 22161. 19. KEY WORDS (Conltinue an, reverse olde It necessemy and Identify by block imbr) Bank protection (WES...20. AmT-RAcT (cothwe areyee &M ffneeeeiny ge Identify by block nmmber) This report provides guidance for incorporating environmental consid- erations...Environmental Effects ....................... 16 * PART IV: STRUCTURAL DESIGNS ..................... 24 4 Composite Revetment ........................ 249

Methodology Investigation of AI(Artificial Intelligence) Test Officer Support Tool. Volume 1

DTIC Science & Technology

1989-03-01

American Association for Artificial inteligence A! ............. Artificial inteliigence AMC ............ Unt:ed States Army Maeriel Comand ASL...block number) FIELD GROUP SUB-GROUP Artificial Intelligence, Expert Systems Automated Aids to Testing 9. ABSTRACT (Continue on reverse if necessary and...identify by block number) This report covers the application of Artificial Intelligence-Techniques to the problem of creating automated tools to

Transmission failure in sympathetic nerves produced by hemicholinium

PubMed Central

Chang, V.; Rand, M. J.

1960-01-01

It has been shown by others that hemicholinium (α,α'-dimethylethanolamino-4,4'-biacetophenone) inhibits the synthesis of acetylcholine, an effect which is reversed by choline. Hemicholinium produces a failure of response to nerve stimulation in the following sympathetically innervated preparations: guinea-pig isolated vas deferens, rabbit isolated uterus, rabbit isolated colon, perfused rabbit ear, cat isolated atria and the piloerector muscles in the cat's tail. The blocking action of hemicholinium on the responses to postganglionic sympathetic stimulation resembles its blocking action against cholinergic nerve stimulation observed on rabbit isolated atria with vagus nerves, rabbit isolated vagina with pelvic nerves, and guinea-pig isolated diaphragm with phrenic nerve. The failure of transmission produced by hemicholinium in sympathetic nerves and in cholinergic nerves can be reversed by choline. It is suggested that if there were a cholinergic junction at sympathetic nerve endings the mechanism of the blocking action of hemicholinium at these endings could be explained by inhibition of acetylcholine synthesis. ImagesFIG. 13FIG. 14 PMID:13692344

Specific and reversible DNA-directed self-assembly of oil-in-water emulsion droplets

PubMed Central

Hadorn, Maik; Boenzli, Eva; Sørensen, Kristian T.; Fellermann, Harold; Eggenberger Hotz, Peter; Hanczyc, Martin M.

2012-01-01

Higher-order structures that originate from the specific and reversible DNA-directed self-assembly of microscopic building blocks hold great promise for future technologies. Here, we functionalized biotinylated soft colloid oil-in-water emulsion droplets with biotinylated single-stranded DNA oligonucleotides using streptavidin as an intermediary linker. We show the components of this modular linking system to be stable and to induce sequence-specific aggregation of binary mixtures of emulsion droplets. Three length scales were thereby involved: nanoscale DNA base pairing linking microscopic building blocks resulted in macroscopic aggregates visible to the naked eye. The aggregation process was reversible by changing the temperature and electrolyte concentration and by the addition of competing oligonucleotides. The system was reset and reused by subsequent refunctionalization of the emulsion droplets. DNA-directed self-assembly of oil-in-water emulsion droplets, therefore, offers a solid basis for programmable and recyclable soft materials that undergo structural rearrangements on demand and that range in application from information technology to medicine. PMID:23175791

U.S. Air Force Research Technology Area Plan, FY 1989

DTIC Science & Technology

1988-09-01

Continue on reverse if necessaty and identify by block number) FIELD GROUP SUB-GROUP 19. ABSTRACT (Continue on reverse if necessary and identify by...Armstrong Aerospace Medical Research Laboratory (AAMRL) USAF School of Aerospace Medical Research Laboratory (USAFSAM) Rome Air Development Center...development of advanced weapon concepts and advance the state of the art in systems development, electromagnetic countermeasures, nuclear weapons

Sugammadex: Appropriate Use in the Context of Budgetary Constraints.

PubMed

Cammu, Guy

2018-01-01

The purpose of this review is to assess how sugammadex impacts postoperative residual curarization using appropriate doses based on neuromuscular transmission monitoring and whether the advantages of sugammadex versus neostigmine outweigh its higher cost. An accurate assessment of neuromuscular blockade with monitoring is necessary before selecting neostigmine versus sugammadex for reversal at the end of surgery to overcome incomplete neuromuscular recovery. The main advantages of sugammadex over neostigmine are its predictability and its ability to extend the range of blockade reversal. The cost of sugammadex is greater when higher doses of sugammadex are required for antagonism of deep block. Sugammadex probably has the potential to be cost-effective compared with neostigmine if its time savings are put to productive use in clinical practice. However, to date, the economic benefits of the drug are unknown. With sugammadex, almost any degree of neuromuscular block can be antagonized within 2-3 min; neostigmine is the only reversal agent effective against benzylisoquinolines and can ideally be used for reversal of lower levels of residual paralysis. The performance of the more expensive sugammadex on improving patient outcomes may depend on several elements of clinical strategy.

Do we really need sugammadex as an antagonist of muscle relaxants in anesthesia?

PubMed

Meistelman, Claude; Donati, François

2016-08-01

Sugammadex is a selective relaxant-binding agent that is designed to encapsulate rocuronium and chemically similar steroidal muscle relaxants such as vecuronium. This review summarizes recent information on the use of sugammadex in clinical practice. The main advantages of sugammadex when compared with conventional anticholinesterase agents are a much faster recovery time and its unique ability to reverse rapidly and efficiently, for the first time, deep levels of neuromuscular blockade. However, there is paucity of evidence-based studies on the benefit of deep neuromuscular block, and then routine administration of sugammadex to reverse any level of block, for example, during laparoscopic surgery. It appears that reduction of costs depends mainly on organizational factors. Finally it must be remembered that sugammadex only works with steroidal nondepolarizing muscle relaxants; therefore neostigmine should not be withdrawn because it is the only reversal agent effective against atracurium or cisatracurium. Sugammadex offers a significantly faster and more predictable recovery profile than neostigmine. It is now possible to reverse rapidly and efficiently any level of neuromuscular blockade and to avoid the risk of adverse events because of residual paralysis such as critical respiratory events during recovery from anesthesia.

Rapid and reversible impairments of short- and long-term social recognition memory are caused by acute isolation of adult rats via distinct mechanisms.

PubMed

Shahar-Gold, Hadar; Gur, Rotem; Wagner, Shlomo

2013-01-01

Mammalian social organizations require the ability to recognize and remember individual conspecifics. This social recognition memory (SRM) can be examined in rodents using their innate tendency to investigate novel conspecifics more persistently than familiar ones. Here we used the SRM paradigm to examine the influence of housing conditions on the social memory of adult rats. We found that acute social isolation caused within few days a significant impairment in acquisition of short-term SRM of male and female rats. Moreover, SRM consolidation into long-term memory was blocked following only one day of social isolation. Both impairments were reversible, but with different time courses. Furthermore, only the impairment in SRM consolidation was reversed by systemic administration of arginine-vasopressin (AVP). In contrast to SRM, object recognition memory was not affected by social isolation. We conclude that acute social isolation rapidly induces reversible changes in the brain neuronal and molecular mechanisms underlying SRM, which hamper its acquisition and completely block its consolidation. These changes occur via distinct, AVP sensitive and insensitive mechanisms. Thus, acute social isolation of rats swiftly causes changes in their brain and interferes with their normal social behavior.

[Conduction block: a notion to let through].

PubMed

Fournier, E

2012-12-01

Historical study of electrodiagnosis indicates that nerve conduction block is an old notion, used as early as the second century by Galien and then early in the 19th by physiologists such as Müller and Mateucci. Although introduced into the field of human pathology by Mitchell in 1872, who used it to study nerve injuries, and then by Erb in 1874 to study radial palsy, the contribution of nerve conduction blocks to electrodiagnosis was not exploited until the 1980s. At that time, attempts to improve early diagnosis of Guillain-Barré syndrome showed that among the electrophysiological consequences of demyelination, conduction block was the most appropriate to account for the paralysis. At the same time, descriptions of neuropathies characterized by conduction blocks led to considering conduction block as a major electrophysiological sign. Why was it so difficult for this sign to be retained for electrodiagnosis? Since the notion is not always associated with anatomical lesions, it doesn't fit easily into anatomoclinical reasoning, but has to be thought of in functional terms. Understanding how an uninjured axon could fail to conduct action potentials leads to an examination of the intimate consequences of demyelinations and axonal dysfunctions. But some of the difficulty encountered in adding this new old sign to the armamentarium of electrophysiological diagnosis was related to the technical precautions required to individualize a block. Several pitfalls have to be avoided if a conduction block is to be afforded real diagnostic value. Similar precautions and discussions are also needed to establish an opposing sign, the "excitability block" or "inverse block". Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Recovery from distal ulnar motor conduction block injury: serial EMG studies.

PubMed

Montoya, Liliana; Felice, Kevin J

2002-07-01

Acute conduction block injuries often result from nerve compression or trauma. The temporal pattern of clinical, electrophysiologic, and histopathologic changes following these injuries has been extensively studied in experimental animal models but not in humans. Our recent evaluation of a young man with an injury to the deep motor branch of the ulnar nerve following nerve compression from weightlifting exercises provided the opportunity to follow the course and recovery of a severe conduction block injury with sequential nerve conduction studies. The conduction block slowly and completely resolved, as did the clinical deficit, over a 14-week period. The reduction in conduction block occurred at a linear rate of -6.1% per week. Copyright 2002 Wiley Periodicals, Inc.

In Vitro Cross-Resistance Profiles of Rilpivirine, Dapivirine, and MIV-150, Nonnucleoside Reverse Transcriptase Inhibitor Microbicides in Clinical Development for the Prevention of HIV-1 Infection.

PubMed

Giacobbi, Nicholas S; Sluis-Cremer, Nicolas

2017-07-01

Rilpivirine (RPV), dapivirine (DPV), and MIV-150 are in development as microbicides. It is not known whether they will block infection of circulating nonnucleoside reverse transcriptase inhibitor (NNRTI)-resistant human immunodeficiency virus type 1 (HIV-1) variants. Here, we demonstrate that the activity of DPV and MIV-150 is compromised by many resistant viruses containing single or double substitutions. High DPV genital tract concentrations from DPV ring use may block replication of resistant viruses. However, MIV-150 genital tract concentrations may be insufficient to inhibit many resistant viruses, including those harboring K103N or Y181C. Copyright © 2017 American Society for Microbiology.

Two modes of polyamine block regulating the cardiac inward rectifier K+ current IK1 as revealed by a study of the Kir2.1 channel expressed in a human cell line

PubMed Central

Ishihara, Keiko; Ehara, Tsuguhisa

2004-01-01

The strong inward rectifier K+ current, IK1, shows significant outward current amplitude in the voltage range near the reversal potential and thereby causes rapid repolarization at the final phase of cardiac action potentials. However, the mechanism that generates the outward IK1 is not well understood. We recorded currents from the inside-out patches of HEK 293T cells that express the strong inward rectifier K+ channel Kir2.1 and studied the blockage of the currents caused by cytoplasmic polyamines, namely, spermine and spermidine. The outward current–voltage (I–V) relationships of Kir2.1, obtained with 5–10μm spermine or 10–100μm spermidine, were similar to the steady-state outward I–V relationship of IK1, showing a peak at a level that is ∼20mV more positive than the reversal potential, with a negative slope at more positive voltages. The relationships exhibited a plateau or a double-hump shape with 1μm spermine/spermidine or 0.1μm spermine, respectively. In the chord conductance–voltage relationships, there were extra conductances in the positive voltage range, which could not be described by the Boltzmann relations fitting the major part of the relationships. The extra conductances, which generated most of the outward currents in the presence of 5–10μm spermine or 10–100μm spermidine, were quantitatively explained by a model that considered two populations of Kir2.1 channels, which were blocked by polyamines in either a high-affinity mode (Mode 1 channel) or a low-affinity mode (Mode 2 channel). Analysis of the inward tail currents following test pulses indicated that the relief from the spermine block of Kir2.1 consisted of an exponential component and a virtually instantaneous component. The fractions of the two components nearly agreed with the fractions of the blockages in Mode 1 and Mode 2 calculated by the model. The estimated proportion of Mode 1 channels to total channels was 0.9 with 0.1–10μm spermine, 0.75 with 1–100μm spermidine, and between 0.75 and 0.9 when spermine and spermidine coexisted. An interaction of spermine/spermidine with the channel at an intracellular site appeared to modify the equilibrium of the two conformational channel states that allow different modes of blockage. Our results suggest that the outward IK1 is primarily generated by channels with lower affinities for polyamines. Polyamines may regulate the amplitude of the outward IK1, not only by blocking the channels but also by modifying the proportion of channels that show different sensitivities to the polyamine block. PMID:14724206

Cholinergically-induced changes in outward currents in hair cells isolated from the semicircular canal of the frog.

PubMed

Housley, G D; Norris, C H; Guth, P S

1990-01-01

Two cholinergically-induced modulations of membrane conductances have been identified in hair cells isolated from the crista ampullaris of the leopard frog (Rana pipiens), using the whole cell recording configuration of the patch clamp technique. Of 56 crista hair cells tested, 28 showed drug-induced changes in membrane current or membrane potential which were repeatable and could be reversed with washout of drug. The predominant effect (observed in 20 hair cells) of acetylcholine (Ach, 100 microM) to 1mM) or carbachol (1 microM to 50 microM) applied to these hair cells was the reduction of an outward current corresponding to a change in conductance of approximately -0.22 nS. This action by Ach on hair cells has been inferred from previous studies of afferent fiber discharge which reported an increase in firing rate with stimulation of efferent fibers or exogenous application of cholinomimetics (Bernard et al., 1985; Valli et al., 1986; Guth et al., 1986; Norris et al., 1988a). The Ach-induced reduction in outward current was associated with a depolarization of the zero-current membrane potential by approximately +2.5 mV. In a total of 8 hair cells, an Ach-induced reversible increase in outward current was recorded. Changes in conductance were approximately +0.13 nS and were associated with a hyperpolarization of the zero-current membrane potential by approximately -2.2 mV. This current increase is likely to be responsible for the inhibitory post-synaptic potentials (IPSPs) which have previously been recorded intracellularly from acoustico-lateralis hair cells during stimulation of the efferent innervation (Flock and Russell, 1976; Ashmore and Russell, 1982; Art et al., 1984, 1985). Of the remaining 28 hair cells, six cells failed to exhibit any change in membrane conductance or membrane potential in the presence of cholinomimetics while an additional 15 cells exhibited decreases, and 7 cells exhibited increases in outward conductance, during application of Ach or carbachol, which were neither reversible with washout nor repeatable. The Ach-induced decrease in outward current could be reversible blocked by removal of Ca2+ from the external solution. The antagonism of the Ach-induced decrease in outward current by atropine (10(-5) M) suggests that this current may correspond to a facilitatory, 'atropine-preferring' Ach receptor mediated response previously identified in the isolated semicircular canal (Norris et al., 1988a).(ABSTRACT TRUNCATED AT 400 WORDS)

A Pt/TiO(2)/Ti Schottky-type selection diode for alleviating the sneak current in resistance switching memory arrays.

PubMed

Park, Woo Young; Kim, Gun Hwan; Seok, Jun Yeong; Kim, Kyung Min; Song, Seul Ji; Lee, Min Hwan; Hwang, Cheol Seong

2010-05-14

This study examined the properties of Schottky-type diodes composed of Pt/TiO(2)/Ti, where the Pt/TiO(2) and TiO(2)/Ti junctions correspond to the blocking and ohmic contacts, respectively, as the selection device for a resistive switching cross-bar array. An extremely high forward-to-reverse current ratio of approximately 10(9) was achieved at 1 V when the TiO(2) film thickness was 19 nm. TiO(2) film was grown by atomic layer deposition at a substrate temperature of 250 degrees C. Conductive atomic force microscopy revealed that the forward current flew locally, which limits the maximum forward current density to < 10 A cm(-2) for a large electrode (an area of approximately 60 000 microm(2)). However, the local current measurement showed a local forward current density as high as approximately 10(5) A cm(-2). Therefore, it is expected that this type of Schottky diode effectively suppresses the sneak current without adverse interference effects in a nano-scale resistive switching cross-bar array with high block density.

Carbon Tetrachloride at Hepatotoxic Levels Blocks Reversibly Gap Junctions between Rat Hepatocytes

NASA Astrophysics Data System (ADS)

Saez, J. C.; Bennett, M. V. L.; Spray, D. C.

1987-05-01

Electrical coupling and dye coupling between pairs of rat hepatocytes were reversibly reduced by brief exposure to halogenated methanes (CBrCl3, CCl4, and CHCl3). The potency of different halomethanes in uncoupling hepatocytes was comparable to their hepatotoxicity in vivo, and the rank order was the same as that of their tendency to form free radicals. The effect of carbon tetrachloride (CCl4) on hepatocytes was substantially reduced by prior treatment with SKF 525A, an inhibitor of cytochrome P-450, and by exposure to the reducing reagent β -mercaptoethanol. Halomethane uncoupling occurred with or without extracellular calcium and did not change intracellular concentrations of calcium and hydrogen ions or the phosphorylation state of the main gap-junctional protein. Thus the uncoupling appears to depend on cytochrome P-450 oxidative metabolism in which free radicals are generated and may result from oxidation of the gap-junctional protein or of a regulatory molecule that leads to closure of gap-junctional channels. Decreases in junctional conductance may be a rapid cellular response to injury that protects healthy cells by uncoupling them from unhealthy ones.

Go for broke: The role of somatic states when asked to lose in the Iowa Gambling Task.

PubMed

Wright, Rebecca J; Rakow, Tim; Russo, Riccardo

2017-02-01

The Somatic Marker Hypothesis (SMH) posits that somatic states develop and guide advantageous decision making by "marking" disadvantageous options (i.e., arousal increases when poor options are considered). This assumption was tested using the standard Iowa Gambling Task (IGT) in which participants win/lose money by selecting among four decks of cards, and an alternative version, identical in both structure and payoffs, but with the aim changed to lose as much money as possible. This "lose" version of the IGT reverses which decks are advantageous/disadvantageous; and so reverses which decks should be marked by somatic responses - which we assessed via skin conductance (SC). Participants learned to pick advantageously in the original (Win) IGT and in the (new) Lose IGT. Using multilevel regression, some variability in anticipatory SC across blocks was found but no consistent effect of anticipatory SC on disadvantageous deck selections. Thus, while we successfully developed a new way to test the central claims of the SMH, we did not find consistent support for the SMH. Copyright © 2016 The Author(s). Published by Elsevier B.V. All rights reserved.

Electrophysiological responses of dissociated type I cells of the rabbit carotid body to cyanide.

PubMed Central

Biscoe, T J; Duchen, M R

1989-01-01

1. The carotid body is the major peripheral sensor of arterial PO2 in the mammal and is excited by cyanide (CN-). Type I cells, the presumed sites for transduction, were freshly dissociated from the carotid body of the adult rabbit and studied with the whole-cell patch clamp technique. 2. Type I cells were hyperpolarized by CN-, the action potential was shortened, and there was an increased after-hyperpolarization. 3. Under voltage clamp control, CN- increased a voltage-dependent outward current, which showed pronounced outward rectification. Tail currents increased by CN- reversed close to the predicted EK, the reversal potential of the CN--induced current depended on extracellular [K+], and the current was blocked by intracellular TEA+ and Cs+. 4. The i-V relation of the CN--induced conductance strongly mirrored that of voltage-gated Ca2+ entry, and the response was abolished by removal of extracellular Ca2+. We conclude that the increased gK is Ca2+ -dependent (gK(Ca]. 5. The Ca2+ current was attenuated by CN-, and showed an increased rate of inactivation. Thus, the increased gK(Ca) must result from an alteration in Ca2+ homeostasis independent of the Ca2+ current, and not an increased Ca2+ entry through voltage-activated channels. 6. Carbachol also hyperpolarized cells and increased a K+ conductance. 7. At depolarized holding potentials a steady-state outward current was increased by CN-. The current reversed close to EK, and was associated with increased current fluctuations. Noise analysis showed that a channel conductance of 3 pS carries the current. 8. The response to CN- was not impaired by the inclusion of 5 mM-MgATP in the patch pipette. 9. If signals to the CNS are initiated by the calcium-dependent release of transmitters from type I cells, transduction would appear to be the direct consequence of the energy dependence of Ca2+ homeostasis. PMID:2557439

Block of calcium channels by enkephalin and somatostatin in neuroblastoma-glioma hybrid NG108-15 cells.

PubMed

Tsunoo, A; Yoshii, M; Narahashi, T

1986-12-01

Leucine-enkephalin, methionine-enkephalin, and morphine caused a reversible block of Ca2+ channel currents in neuroblastoma-glioma hybrid cells (NG108-15). The long-lasting (type 2) component of the Ca2+ channel current was blocked by leucine-enkephalin, while the transient (type 1) component was not affected. The enkephalin-induced blocking action was antagonized by naloxone and appears to be mediated by delta-opiate receptors. Two different aspects of the blocking effect were detected, a resting block and a recovery from block during prolonged depolarizing pulses. Recovery from block was more complete, and its time course was more rapid, with depolarization to more positive potentials. The dose dependence of the type 2 channel block at rest indicated a one-to-one binding stoichiometry, with an apparent dissociation constant of 8.8 nM. Somatostatin exerted a similar selective blocking action on the type 2 Ca2+ channel. The time- and voltage-dependent block of type 2 Ca2+ channels may provide a mechanism underlying the enkephalinergic presynaptic inhibition of transmitter release and the somatostatin block of pituitary growth hormone release.

Acetylcholine Mediates a Slow Synaptic Potential in Hippocampal Pyramidal Cells

NASA Astrophysics Data System (ADS)

Cole, A. E.; Nicoll, R. A.

1983-09-01

The hippocampal slice preparation was used to study the role of acetylcholine as a synaptic transmitter. Bath-applied acetylcholine had three actions on pyramidal cells: (i) depolarization associated with increased input resistance, (ii) blockade of calcium-activated potassium responses, and (iii) blockade of accommodation of cell discharge. All these actions were reversed by the muscarinic antagonist atropine. Stimulation of sites in the slice known to contain cholinergic fibers mimicked all the actions. Furthermore, these evoked synaptic responses were enhanced by the cholinesterase inhibitor eserine and were blocked by atropine. These findings provide electrophysiological support for the role of acetylcholine as a synaptic transmitter in the brain and demonstrate that nonclassical synaptic responses involving the blockade of membrane conductances exist in the brain.

Musculoskeletal injuries in professional modern dancers: a prospective cohort study of 15 years.

PubMed

Bronner, Shaw; McBride, Caroline; Gill, Allison

2018-08-01

We analysed work-related musculoskeletal injuries (WMSI) in two modern dance companies to determine whether injury rates decreased and patterns altered compared to previous 3-yr and 6-yr audits (0.48 and 0.25/1000-hrs exposure respectively). In this prospectively designed 15-yr cohort study, data were collected in 30-dancer Company-1 and 12-dancer Company-2. In-house physical therapists tracked WMSI and time-loss-injuries for 159 dancers (42 dancers/yr). 15-yrs were grouped into five 3-yr blocks for comparison with prior audits. Negative binomial logistic regression analyses were conducted with exposure-hrs converted to the natural log and used as the offset variable. Block and company were categorical predictors for dependent variables: WMSI, time-loss-injuries, trauma-injuries and overuse-injuries (p < 0.05). 69% of dancers reported WMSI; 45% sustained at least one time-loss-injury. Company-1, with greater annual exposure, was 1.6-times more likely to sustain time-loss-injuries (p = 0.016, CI = 1.095-2.422) and 5.6-times more likely to sustain time-loss overuse-injuries (p = 0.003, CI = 1.812-17.327). Compared to Block-1, WMSI and time-loss-injuries decreased in Blocks-2, 3, and 5 (p ≤ 0.027). The ratio of time-loss overuse to trauma-injuries was reversed, with trauma-injuries accounting for over 80% of injuries by Block 5. Time-loss-injuries averaged 0.16 injuries/1000-hrs, lower than rates in ballet and sports. Decreased injury rates and changed injury patterns demonstrate efficacious injury management and prevention programming.

Preparing for the unexpected: special considerations and complications after sugammadex administration.

PubMed

Iwasaki, Hajime; Renew, J Ross; Kunisawa, Takayuki; Brull, Sorin J

2017-10-17

Sugammadex, a modified gamma-cyclodextrin, has changed clinical practice of neuromuscular reversal dramatically. With the introduction of this selective relaxant binding agent, rapid and reliable neuromuscular reversal from any depth of block became possible. Sugammadex can reverse neuromuscular blockade without the muscarinic side effects typically associated with the administration of acetylcholinesterase inhibitors. However, what remained unchanged is the incidence of residual neuromuscular blockade. It is known that sugammadex cannot always prevent its occurrence, if appropriate dosing is not chosen based on the level of neuromuscular paralysis prior to administration determined by objective neuromuscular monitoring. Alternatively, excessive doses of sugammadex administered in an attempt to ensure full and sustained reversal may affect the effectiveness of rocuronium in case of immediate reoperation or reintubation. In such emergent scenarios that require onset of rapid and reliable neuromuscular blockade, the summary of product characteristics (package insert) recommends using benzylisoquinolinium neuromuscular blocking agents or a depolarizing agent. However, if rapid intubation is required, succinylcholine has a significant number of side effects, and benzylisoquinolinium agents may not have the rapid onset required. Therefore, prior administration of sugammadex introduces a new set of potential problems that require new solutions. This novel reversal agent thus presents new challenges and anesthesiologists must familiarize themselves with specific issues with its use (e.g., bleeding risk, hypermagnesemia, hypothermia). This review will address sugammadex administration in such special clinical situations.

Static Performance of Six Innovative Thrust Reverser Concepts for Subsonic Transport Applications: Summary of the NASA Langley Innovative Thrust Reverser Test Program

NASA Technical Reports Server (NTRS)

Asbury, Scott C.; Yetter, Jeffrey A.

2000-01-01

The NASA Langley Configuration Aerodynamics Branch has conducted an experimental investigation to study the static performance of innovative thrust reverser concepts applicable to high-bypass-ratio turbofan engines. Testing was conducted on a conventional separate-flow exhaust system configuration, a conventional cascade thrust reverser configuration, and six innovative thrust reverser configurations. The innovative thrust reverser configurations consisted of a cascade thrust reverser with porous fan-duct blocker, a blockerless thrust reverser, two core-mounted target thrust reversers, a multi-door crocodile thrust reverser, and a wing-mounted thrust reverser. Each of the innovative thrust reverser concepts offer potential weight savings and/or design simplifications over a conventional cascade thrust reverser design. Testing was conducted in the Jet-Exit Test Facility at NASA Langley Research Center using a 7.9%-scale exhaust system model with a fan-to-core bypass ratio of approximately 9.0. All tests were conducted with no external flow and cold, high-pressure air was used to simulate core and fan exhaust flows. Results show that the innovative thrust reverser concepts achieved thrust reverser performance levels which, when taking into account the potential for system simplification and reduced weight, may make them competitive with, or potentially more cost effective than current state-of-the-art thrust reverser systems.

A Facile Molten-Salt Route for Large-Scale Synthesis of NiFe2O4 Nanoplates with Enhanced Lithium Storage Capability.

PubMed

Huang, Gang; Du, Xinchuan; Zhang, Feifei; Yin, Dongming; Wang, Limin

2015-09-28

Binary metal oxides have been deemed as a promising class of electrode materials for high-performance lithium ion batteries owing to their higher conductivity and electrochemical activity than corresponding monometal oxides. Here, NiFe2O4 nanoplates consisting of nanosized building blocks have been successfully fabricated by a facile, large-scale NaCl and KCl molten-salt route, and the changes in the morphology of NiFe2O4 as a function of the molten-salt amount have been systemically investigated. The results indicate that the molten-salt amount mainly influences the diameter and thickness of the NiFe2O4 nanoplates as well as the morphology of the nanosized building blocks. Cyclic voltammetry (CV) and galvanostatic charge-discharge measurements have been conducted to evaluate the lithium storage properties of the NiFe2O4 nanoplates prepared with a Ni(NO3)2/Fe(NO3)3/KCl/NaCl molar ratio of 1:2:20:60. A high reversible capacity of 888 mAh g(-1) is delivered over 100 cycles at a current density of 100 mA g(-1). Even at a current density of 5000 mA g(-1) , the discharge capacity could still reach 173 mAh g(-1). Such excellent electrochemical performances of the NiFe2O4 nanoplates are contributed to the short Li(+) diffusion distance of the nanosized building blocks and the synergetic effect of the Ni(2+) and Fe(3+) ions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Monovalent Cation Permeation through the Connexin40 Gap Junction Channel

PubMed Central

Beblo, Dolores A.; Veenstra, Richard D.

1997-01-01

The unitary conductances and permeability sequences of the rat connexin40 (rCx40) gap junction channels to seven monovalent cations and anions were studied in rCx40-transfected neuroblastoma 2A (N2A) cell pairs using the dual whole cell recording technique. Chloride salt cation substitutions (115 mM principal salt) resulted in the following junctional maximal single channel current-voltage relationship slope conductances (γj in pS): CsCl (153), RbCl (148), KCl (142), NaCl (115), LiCl (86), TMACl (71), TEACl (63). Reversible block of the rCx40 channel was observed with TBA. Potassium anion salt γj are: Kglutamate (160), Kacetate (160), Kaspartate (158), KNO3 (157), KF (148), KCl (142), and KBr (132). Ion selectivity was verified by measuring reversal potentials for current in rCx40 gap junction channels with asymmetric salt solutions in the two electrodes and using the Goldman-Hodgkin-Katz equation to calculate relative permeabilities. The permeabilities relative to Li+ are: Cs+ (1.38), Rb+ (1.32), K+ (1.31), Na+ (1.16), TMA+ (0.53), TEA+ (0.45), TBA+ (0.03), Cl− (0.19), glutamate− (0.04), and NO3− (0.14), assuming that the monovalent anions permeate the channel by forming ion pairs with permeant monovalent cations within the pore thereby causing proportionate decreases in the channel conductance. This hypothesis can account for why the predicted increasing conductances with increasing ion mobilities in an essentially aqueous channel were not observed for anions in the rCx40 channel. The rCx40 effective channel radius is estimated to be 6.6 Å from a theoretical fit of the relationship of relative permeability and cation radius. PMID:9101408

Comparative effects of sodium bicarbonate and sodium chloride on reversing cocaine-induced changes in the electrocardiogram.

PubMed

Parker, R B; Perry, G Y; Horan, L G; Flowers, N C

1999-12-01

Cocaine abuse is associated with a number of cardiovascular complications that include arrhythmias and sudden cardiac death. Although the mechanism(s) remain unclear, cocaine-induced block of sodium channels resulting in slowed cardiac conduction is thought to play an important role. Several reports suggest that the effects of cocaine effects on cardiac sodium channels can be reversed by administration of sodium bicarbonate. Whether the beneficial effects of sodium bicarbonate are due to sodium ions or an increase in blood pH is unknown. Therefore the purpose of this study was to compare the effects of sodium loading alone (by using sodium chloride) versus sodium loading with an associated increase in arterial pH (by using sodium bicarbonate) on reversing cocaine-induced effects on the electrocardiogram (ECG) in a canine model. Seventeen anesthetized dogs received three i.v. injections of cocaine, 5 mg/kg, with each dose separated by 15 min. Two minutes after the third cocaine dose, each dog was randomly assigned to receive 2 mEq/kg i.v. sodium bicarbonate (1 mEq/ml) or 2 mEq/kg i.v. sodium chloride (1 mEq/ml). ECG, electrophysiologic, and hemodynamic data were recorded at baseline, after each cocaine injection, and after administration of sodium bicarbonate or sodium chloride. In both groups of animals, the first cocaine injection significantly (p < 0.05) prolonged the PR, QTc, AH, and HV intervals, and QRS duration compared with baseline. All intervals continued to lengthen in a dose-dependent manner after the second and third cocaine doses. Sodium bicarbonate significantly (p < 0.05) reduced cocaine-induced prolongation of PR [(147 +/- 5-130 +/- 5 ms), AH (81 +/- 6 - 72 +/- 6 ms), and HV intervals (55 +/- 2 - 39 +/- 1 ms). and QRS duration (96 +/- 6 - 66 +/- 4 ms), peak effect after third cocaine dose versus after sodium bicarbonate, respectively]. Sodium chloride had no effect on reversing cocaine-induced effects on the ECG. Cocaine produces dose-dependent slowing of cardiac conduction that is effectively reversed by sodium bicarbonate. The lack of efficacy of sodium chloride suggests that the increase in arterial pH associated with sodium bicarbonate is responsible for reversal of the effects of cocaine on the ECG. Therefore sodium bicarbonate may be clinically useful in the treatment of cocaine-induced cardiac arrhythmias, primarily as a result of its effects on arterial pH.

Mode Medium Interaction. A Theoretical Study.

DTIC Science & Technology

1980-09-01

Report) 10. SUPPLEMENTARY NOTES I9. KEY WORDS (Conrlfnue on reverse side II necessary mnd Identify by block rumber) CO, Laser Transfer Function...Chemical Laser Unstable Resonator Brillouin Scattering Instability Supersonic Laser Modes Acoustic Noise Acoustic Instability Perturbed Resonator Gain...end Identify by block number) An instability in the output of a high-power unstable-resonator cw CO2 laser is analyzed in terms of the perturbative

Updated optical read/write memory system components

NASA Technical Reports Server (NTRS)

1974-01-01

A survey of the building blocks of the electro-optic read/write system was made. Critical areas and alternate paths are discussed. The latest PLZT block data composer is analyzed. Stricter controls in the production and fabrication of PLZT are implied by the performance of the BDC. A reverse charge before erase has eliminated several problems observed in the parallel plane charging process for photoconductor-thermoplastic hologram storage.

Laser-Induced Thermal Damage of Skin

DTIC Science & Technology

1977-12-01

identify by block number) Skin Burns Skin Model Laser Effects \\Thermal Predictions 20 ABSTRACT (Continue on reverse side it necessary and identify by...block number) A computerized model was developed for predicting thermal damage of skin by laser exposures. Thermal, optical, and physiological data are...presented for the model. Model predictions of extent of irreversible damage were compared with histologic determinations of the extent of damage

Doxorubicin-loaded micelles of reverse poly(butylene oxide)-poly(ethylene oxide)-poly(butylene oxide) block copolymers as efficient "active" chemotherapeutic agents.

PubMed

Cambón, A; Rey-Rico, A; Mistry, D; Brea, J; Loza, M I; Attwood, D; Barbosa, S; Alvarez-Lorenzo, C; Concheiro, A; Taboada, P; Mosquera, V

2013-03-10

Five reverse poly(butylene oxide)-poly(ethylene oxide)-poly(butylene oxide) block copolymers, BOnEOmBOn, with BO ranging from 8 to 21 units and EO from 90 to 411 were synthesized and evaluated as efficient chemotherapeutic drug delivery nanocarriers and inhibitors of the P-glycoprotein (P-gp) efflux pump in a multidrug resistant (MDR) cell line. The copolymers were obtained by reverse polymerization of poly(butylene oxide), which avoids transfer reaction and widening of the EO block distribution, commonly found in commercial poly(ethylene oxide)-poly(propylene oxide) block copolymers (poloxamers). BOnEOmBOn copolymers formed spherical micelles of 10-40 nm diameter at lower concentrations (one order of magnitude) than those of equivalent poloxamers. The influence of copolymer block lengths and BO/EO ratios on the solubilization capacity and protective environment for doxorubicin (DOXO) was investigated. Micelles showed drug loading capacity ranging from ca. 0.04% to 1.5%, more than 150 times the aqueous solubility of DOXO, and protected the cargo from hydrolysis for more than a month due to their greater colloidal stability in solution. Drug release profiles at various pHs, and the cytocompatibility and cytotoxicity of the DOXO-loaded micelles were assessed in vitro. DOXO loaded in the polymeric micelles accumulated more slowly inside the cells than free DOXO due to its sustained release. All copolymers were found to be cytocompatible, with viability extents larger than 95%. In addition, the cytotoxicity of DOXO-loaded micelles was higher than that observed for free drug solutions in a MDR ovarian NCI-ADR-RES cell line which overexpressed P-gp. The inhibition of the P-gp efflux pump by some BOnEOmBOn copolymers, similar to that measured for the common P-gp inhibitor verapamil, favored the retention of DOXO inside the cell increasing its cytotoxic activity. Therefore, poly(butylene oxide)-poly(ethylene oxide) block copolymers offer interesting features as cell response modifiers to complement their role as efficient nanocarriers for cancer chemotherapy. Copyright © 2013 Elsevier B.V. All rights reserved.

A deletion mutation in the 5' part of the pol gene of Moloney murine leukemia virus blocks proteolytic processing of the gag and pol polyproteins.

PubMed Central

Crawford, S; Goff, S P

1985-01-01

Deletion mutations in the 5' part of the pol gene of Moloney murine leukemia virus were generated by restriction enzyme site-directed mutagenesis of cloned proviral DNA. DNA sequence analysis indicated that one such deletion was localized entirely within the 5' part of the pol gene, did not affect the region encoding reverse transcriptase, and preserved the translational reading frame downstream of the mutation. The major viral precursor polyproteins (Pr65gag, Pr200gag-pol, and gPr80env) were synthesized at wild-type levels in cell lines carrying the mutant genome. These cell lines assembled and released wild-type levels of virion particles into the medium. Cleavage of both Pr65gag and Pr200gag-pol precursors to the mature proteins was completely blocked in the mutant virions. Surprisingly, these virions contained high levels of active reverse transcriptase; examination of the endogenous reverse transcription products synthesized by the mutant virions revealed normal amounts of minus-strand strong-stop DNA, indicating that the RNA genome was packaged and that reverse transcription in detergent-permeabilized virions was not significantly impaired. Processing of gPr80env to gP70env and P15E was not affected by the mutation, but cleavage of P15E to P12E was not observed. The mutant particles were poorly infectious; analysis indicated that infection was blocked at an early stage. The data are consistent with the idea that the 5' part of the pol gene encodes a protease directly responsible for processing Pr65gag, and possibly Pr200gag-pol, to the structural virion proteins. It appears that cleavage of the gag gene product is not required for budding and release of virions and that complete processing of the pol gene product to the mature form of reverse transcriptase is not required for its functional activation. Images PMID:3882995

Identification of types of landings after blocking in volleyball associated with risk of ACL injury.

PubMed

Zahradnik, David; Jandacka, Daniel; Farana, Roman; Uchytil, Jaroslav; Hamill, Joseph

2017-03-01

Landing with a low knee flexion angle after volleyball block jumps may be associated with an increased risk of anterior cruciate ligament (ACL) injury. The aim of the present study was to identify the types of volleyball landings after blocks where the knee flexion angle is found to be under a critical knee flexion angle value of 30° at the instant of the first peak of the ground reaction force (GRF). Synchronized kinematic and kinetic data were collected for each trial. T-tests were used to determine if each knee flexion angle at the instant of the peak GRF was significantly different from the critical value of 30°. A repeated measures ANOVA was used to compare knee flexion angle, time to first peak and the magnitude of the first peak of the resultant GRF and knee stiffness. Significantly lower knee flexion angles were found in the "go" landing (p = .01, ES = 0.6) and the "reverse" landing (p = .02, ES = 0.6) only. The results for knee flexion angle and GRF parameters indicated a significant difference between a "reverse" and "go" and other types of landings, except the "side stick" landing for GRF. The "reverse" and "go" landings may present a risk for ACL injury due to the single-leg landing of these activities that have an associated mediolateral movement.

Prior-Based Quantization Bin Matching for Cloud Storage of JPEG Images.

PubMed

Liu, Xianming; Cheung, Gene; Lin, Chia-Wen; Zhao, Debin; Gao, Wen

2018-07-01

Millions of user-generated images are uploaded to social media sites like Facebook daily, which translate to a large storage cost. However, there exists an asymmetry in upload and download data: only a fraction of the uploaded images are subsequently retrieved for viewing. In this paper, we propose a cloud storage system that reduces the storage cost of all uploaded JPEG photos, at the expense of a controlled increase in computation mainly during download of requested image subset. Specifically, the system first selectively re-encodes code blocks of uploaded JPEG images using coarser quantization parameters for smaller storage sizes. Then during download, the system exploits known signal priors-sparsity prior and graph-signal smoothness prior-for reverse mapping to recover original fine quantization bin indices, with either deterministic guarantee (lossless mode) or statistical guarantee (near-lossless mode). For fast reverse mapping, we use small dictionaries and sparse graphs that are tailored for specific clusters of similar blocks, which are classified via tree-structured vector quantizer. During image upload, cluster indices identifying the appropriate dictionaries and graphs for the re-quantized blocks are encoded as side information using a differential distributed source coding scheme to facilitate reverse mapping during image download. Experimental results show that our system can reap significant storage savings (up to 12.05%) at roughly the same image PSNR (within 0.18 dB).

Catheter ablation as a treatment of atrioventricular block.

PubMed

Tuohy, Stephen; Saliba, Walid; Pai, Manjunath; Tchou, Patrick

2018-01-01

Symptomatic second-degree atrioventricular (AV) block is typically treated by implantation of a pacemaker. An otherwise healthy AV conduction system can nevertheless develop AV block due to interference from junctional extrasystoles. When present with a high burden, these can produce debilitating symptoms from AV block despite an underlying normal AV node and His-Purkinje system properties. The purpose of this study was to describe a catheter ablation approach for alleviating symptomatic AV block due to a ventricular nodal pathway interfering with AV conduction. Common clinical monitoring techniques such as Holter and event recorders were used. Standard electrophysiological study techniques using multipolar recording and ablation catheters were utilized during procedures. A 55-year-old woman presented with highly symptomatic, high-burden second-degree AV block due to concealed and manifest junctional premature beats. Electrophysiological characteristics indicated interference of AV conduction due to a concealed ventricular nodal pathway as the cause of the AV block. The patient's AV nodal and His-Purkinje system conduction characteristics were otherwise normal. Radiofrequency catheter ablation of the pathway was successful in restoring normal AV conduction and eliminating her clinical symptoms. Pathways inserting into the AV junction can interfere with AV conduction. When present at a high burden, this type of AV block can be highly symptomatic. Catheter ablation techniques can be used to alleviate this type of AV block and restore normal AV conduction. Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Gestural recovery and the role of forward and reversed syllabic repetitions as stuttering inhibitors in adults.

PubMed

Kalinowski, Joseph; Saltuklaroglu, Tim; Guntupalli, Vijaya; Stuart, Andrew

2004-06-10

Instead of being the core stuttering 'problem', syllabic repetitions may be a biological mechanism, or 'solution', to the central involuntary stuttering block. Simply put, stuttering is an endogenous transitory state of 'shadowed speech', a choral speech derivative that allows for a neural release of the central block. To investigate this possibility, 14 adults who stutter read while listening to forward fluent speech, reversed fluent speech, forward stuttered speech, and reversed stuttered speech. All conditions induced significant degrees of stuttering inhibition when compared to a control condition. However, the reversed fluent condition was less powerful than the other three conditions ( approximately 42% vs. approximately 65%) for inhibiting stuttering. Stuttering inhibition appears to proceed by 'gestural recovery', made possible by the presence of an exogenous or 'second' set of speech gestures and engagement of mirror neurons. When reversed fluent speech was used, violations in normal gesture-time relationships (i.e., normal speech entropy) resulted in gestural configurations that apparently were inadequately recovered, and therefore, were not as conducive to high levels of stuttering inhibition. In contrast, high levels of encoding found in the simple syllabic structures of stuttered speech allowed its forward and reversed forms to be equally effective for gestural recovery and stuttering inhibition. The reversal of repeated syllables did not appear to significantly degrade the natural gesture-time relationships (i.e., they were perceptually recognizable). Thus, exogenous speech gestures that displayed near normal gestural relationships allowed for easy recovery and fluent productions via mirror systems, suggesting a more choral-like nature. The importance of syllabic repetitions is highlighted: both their perceived (exogenous) and produced (endogenous) forms appear to be fundamental, surface acoustic manifestations for central stuttering inhibition via the engagement of mirror neurons.

Dexamethasone Does Not Inhibit Sugammadex Reversal After Rocuronium-Induced Neuromuscular Block.

PubMed

Buonanno, Pasquale; Laiola, Anna; Palumbo, Chiara; Spinelli, Gianmario; Servillo, Giuseppe; Di Minno, Raffaele Maria; Cafiero, Tullio; Di Iorio, Carlo

2016-06-01

Sugammadex is a relatively new molecule that reverses neuromuscular block induced by rocuronium. The particular structure of sugammadex traps the cyclopentanoperhydrophenanthrene ring of rocuronium in its hydrophobic cavity. Dexamethasone shares the same steroidal structure with rocuronium. Studies in vitro have demonstrated that dexamethasone interacts with sugammadex, reducing its efficacy. In this study, we investigated the clinical relevance of this interaction and its influence on neuromuscular reversal. In this retrospective case-control study, we analyzed data from 45 patients divided into 3 groups: dexamethasone after induction group (15 patients) treated with 8 mg dexamethasone as an antiemetic drug shortly after induction of anesthesia; dexamethasone before reversal group (15 patients) treated with dexamethasone just before sugammadex injection; and control group (15 patients) treated with 8 mg ondansetron. All groups received 0.6 mg/kg rocuronium at induction, 0.15 mg/kg rocuronium at train-of-four ratio (TOF) 2 for neuromuscular relaxation, and 2 mg/kg sugammadex for reversal at the end of the procedure at TOF2. Neuromuscular relaxation was monitored with a TOF-Watch® system. The control group had a recovery time of 154 ± 54 seconds (mean ± SD), the dexamethasone after induction group 134 ± 55 seconds, and the dexamethasone before reversal group 131 ± 68 seconds. The differences among groups were not statistically significant (P = 0.5141). Our results show that the use of dexamethasone as an antiemetic drug for the prevention of postoperative nausea and vomiting does not interfere with reversal of neuromuscular blockade with sugammadex in patients undergoing elective surgery with general anesthesia in contrast to in vitro studies that support this hypothesis.

Rapid evaluation of reverse-osmosis membranes

NASA Technical Reports Server (NTRS)

Hollahan, J. R.; Wydeven, T.

1972-01-01

Simultaneous reverse-osmosis tests conducted with centrifuges having multiple compartment heads are discussed. Equipment for retaining reverse-osmosis membrane is illustrated. Method of conducting tests is described.

Vpx complementation of 'non-macrophage tropic' R5 viruses reveals robust entry of infectious HIV-1 cores into macrophages.

PubMed

Mlcochova, Petra; Watters, Sarah A; Towers, Greg J; Noursadeghi, Mahdad; Gupta, Ravindra K

2014-03-21

It is now known that clinically derived viruses are most commonly R5 tropic with very low infectivity in macrophages. As these viruses utilize CD4 inefficiently, defective entry has been assumed to be the dominant restriction. The implication is that macrophages are not an important reservoir for the majority of circulating viruses. Macrophage infection by clinical transmitted/founder isolates was 10-100 and 30-450 fold less efficient as compared to YU-2 and BaL respectively. Vpx complementation augmented macrophage infection by non-macrophage tropic viruses to the level of infectivity observed for YU-2 in the absence of Vpx. Augmentation was evident even when Vpx was provided 24 hours post-infection. The entry defect was measured as 2.5-5 fold, with a further 3.5-10 fold block at strong stop and subsequent stages of reverse transcription as compared to YU-2. The overall block to infection was critically dependent on the mechanism of entry as demonstrated by rescue of infection after pseudotyping with VSV-G envelope. Reverse transcription in macrophages could not be enhanced using a panel of cytokines or lipopolysaccharide (LPS). Although the predominant block to clinical transmitted/founder viruses is post-entry, infectivity is determined by Env-CD4 interactions and can be rescued with VSV-G pseudotyping. This suggests a functional link between the optimal entry pathway taken by macrophage tropic viruses and downstream events required for reverse transcription. Consistent with a predominantly post-entry block, replication of R5 using viruses can be greatly enhanced by Vpx. We conclude therefore that entry is not the limiting step and that macrophages represent clinically relevant reservoirs for 'non-macrophage tropic' viruses.

Two distinct classes of functional α7-containing nicotinic receptor on rat superior cervical ganglion neurons

PubMed Central

Cuevas, Javier; Roth, Adelheid L; Berg, Darwin K

2000-01-01

Nicotinic acetylcholine receptors (nAChRs) that bind α-bungarotoxin (αBgt) were studied on isolated rat superior cervical ganglion (SCG) neurons using whole-cell patch clamp recording techniques.Rapid application of ACh onto the soma of voltage clamped neurons evoked a slowly desensitizing current that was reversibly blocked by αBgt (50 nm). The toxin-sensitive current constituted on average about half of the peak whole-cell response evoked by ACh.Nanomolar concentrations of methyllycaconitine blocked the αBgt-sensitive component of the ACh-evoked current as did intracellular dialysis with an anti-α7 monoclonal antibody. The results indicate that the slowly reversible toxin-sensitive response elicited by ACh arises from activation of an unusual class of α7-containing receptor (α7-nAChR) similar to that reported previously for rat intracardiac ganglion neurons.A second class of functional α7-nAChR was identified on some SCG neurons by using rapid application of choline to elicit responses. In these cases a biphasic response was obtained, which included a rapidly desensitizing component that was blocked by αBgt in a pseudo-irreversible manner. The pharmacology and kinetics of the responses resembled those previously attributed to α7-nAChRs in a number of other neuronal cell types.Experiments measuring the dissociation rate of 125I-labelled αBgt from SCG neurons revealed two classes of toxin-binding site. The times for toxin dissociation were consistent with those required to reverse blockade of the two kinds of αBgt-sensitive response.These results indicate that rat SCG neurons express two types of functional α7-nAChR, differing in pharmacology, desensitization and reversibility of αBgt blockade. PMID:10856125

Neostigmine but not sugammadex impairs upper airway dilator muscle activity and breathing

PubMed Central

Eikermann, M.; Zaremba, S.; Malhotra, A.; Jordan, A. S.; Rosow, C.; Chamberlin, N. L.

2008-01-01

Background Cholinesterase inhibitor-based reversal agents, given in the absence of neuromuscular block, evoke a partial upper airway obstruction by decreasing skeletal upper airway muscle function. Sugammadex reverses neuromuscular block by encapsulating rocuronium. However, its effects on upper airway integrity and breathing are unknown. Methods Fifty-one adult male rats were anaesthetized with isoflurane, tracheostomized, and a femoral artery and vein were cannulated. First, we compared the efficacy of sugammadex 15 mg kg−1 and neostigmine 0.06 mg kg−1 to reverse respiratory effects of rocuronium-induced partial paralysis [train-of-four ratio (T4/T1)=0.5]. Subsequently, we compared the safety of sugammadex and neostigmine given after recovery of the T4/T1 to 1, by measuring phasic genioglossus activity and breathing. Results During partial paralysis (T4/T1=0.5), time to recovery of minute volume to baseline values was 10.9 (2), 75.8 (18), and 153 (54) s with sugammadex, neostigmine, and placebo, respectively (sugammadex was significantly faster than neostigmine and placebo, P<0.05). Recovery of T4/T1 was also faster for sugammadex than neostigmine and placebo. Neostigmine administration after complete recovery of T4/T1 decreased upper airway dilator muscle activity to 64 (30)% of baseline and decreased tidal volume (P<0.05 for both variables), whereas sugammadex had no effect on either variable. Conclusions In contrast to neostigmine, which significantly impairs upper airway dilator muscle activity when given after recovery from neuromuscular block, a reversal dose of sugammadex given under the same conditions does not affect genioglossus muscle activity and normal breathing. Human studies will be required to evaluate the clinical relevance of our findings. PMID:18559352

Characterization of the cloned human intermediate-conductance Ca2+-activated K+ channel.

PubMed

Jensen, B S; Strobaek, D; Christophersen, P; Jorgensen, T D; Hansen, C; Silahtaroglu, A; Olesen, S P; Ahring, P K

1998-09-01

The human intermediate-conductance, Ca2+-activated K+ channel (hIK) was identified by searching the expressed sequence tag database. hIK was found to be identical to two recently cloned K+ channels, hSK4 and hIK1. RNA dot blot analysis showed a widespread tissue expression, with the highest levels in salivary gland, placenta, trachea, and lung. With use of fluorescent in situ hybridization and radiation hybrid mapping, hIK mapped to chromosome 19q13.2 in the same region as the disease Diamond-Blackfan anemia. Stable expression of hIK in HEK-293 cells revealed single Ca2+-activated K+ channels exhibiting weak inward rectification (30 and 11 pS at -100 and +100 mV, respectively). Whole cell recordings showed a noninactivating, inwardly rectifying K+ conductance. Ionic selectivity estimated from bi-ionic reversal potentials gave the permeability (PK/PX) sequence K+ = Rb+ (1.0) > Cs+ (10.4) > Na+, Li+, N-methyl-D-glucamine (>51). NH+4 blocked the channel completely. hIK was blocked by the classical inhibitors of the Gardos channel charybdotoxin (IC50 28 nM) and clotrimazole (IC50 153 nM) as well as by nitrendipine (IC50 27 nM), Stichodactyla toxin (IC50 291 nM), margatoxin (IC50 459 nM), miconazole (IC50 785 nM), econazole (IC50 2.4 microM), and cetiedil (IC50 79 microM). Finally, 1-ethyl-2-benzimidazolinone, an opener of the T84 cell IK channel, activated hIK with an EC50 of 74 microM.

Combined KHFAC+DC nerve block without onset or reduced nerve conductivity after block

PubMed Central

Franke, Manfred; Vrabec, Tina; Wainright, Jesse; Bhadra, Niloy; Bhadra, Narendra; Kilgore, Kevin

2017-01-01

Background Kilohertz Frequency Alternating Current waveforms (KHFAC) have been shown to provide peripheral nerve conductivity block in many acute and chronic animal models. KHFAC nerve block could be used to address multiple disorders caused by neural over-activity, including blocking pain and spasticity. However, one drawback of KHFAC block is a transient activation of nerve fibers during the initiation of the nerve block, called the onset response. The objective of this study is to evaluate the feasibility of using charge balanced direct current (CBDC) waveforms to temporarily block motor nerve conductivity distally to the KHFAC electrodes to mitigate the block onset-response. Methods A total of eight animals were used in this study. A set of four animals were used to assess feasibility and reproducibility of a combined KHFAC+CBDC block. A following randomized study, conducted on a second set of four animals, compared the onset response resulting from KHFAC alone and combined KHFAC+CBDC waveforms. To quantify the onset, peak forces and the force-time integral were measured during KHFAC block initiation. Nerve conductivity was monitored throughout the study by comparing muscle twitch forces evoked by supra-maximal stimulation proximal and distal to the block electrodes. Each animal of the randomized study received at least 300 seconds (range: 318 to 1563s) of cumulative DC to investigate the impact of combined KHFAC+CBDC on nerve viability. Results The peak onset force was reduced significantly from 20.73 N (range: 18.6–26.5 N) with KHFAC alone to 0.45 N (range: 0.2–0.7 N) with the combined CBDC and KHFAC block waveform (p<0.001). The area under the force curve was reduced from 6.8 Ns (range: 3.5–21.9 Ns) to 0.54 Ns (range: 0.18–0.86Ns) (p<0.01). No change in nerve conductivity was observed after application of the combined KHFAC+CBDC block relative to KHFAC waveforms. Conclusion The distal application of CBDC can significantly reduce or even completely prevent the KHFAC onset response without a change in nerve conductivity. PMID:25115572

Combined KHFAC + DC nerve block without onset or reduced nerve conductivity after block

NASA Astrophysics Data System (ADS)

Franke, Manfred; Vrabec, Tina; Wainright, Jesse; Bhadra, Niloy; Bhadra, Narendra; Kilgore, Kevin

2014-10-01

Objective. Kilohertz frequency alternating current (KHFAC) waveforms have been shown to provide peripheral nerve conductivity block in many acute and chronic animal models. KHFAC nerve block could be used to address multiple disorders caused by neural over-activity, including blocking pain and spasticity. However, one drawback of KHFAC block is a transient activation of nerve fibers during the initiation of the nerve block, called the onset response. The objective of this study is to evaluate the feasibility of using charge balanced direct current (CBDC) waveforms to temporarily block motor nerve conductivity distally to the KHFAC electrodes to mitigate the block onset-response. Approach. A total of eight animals were used in this study. A set of four animals were used to assess feasibility and reproducibility of a combined KHFAC + CBDC block. A following randomized study, conducted on a second set of four animals, compared the onset response resulting from KHFAC alone and combined KHFAC + CBDC waveforms. To quantify the onset, peak forces and the force-time integral were measured during KHFAC block initiation. Nerve conductivity was monitored throughout the study by comparing muscle twitch forces evoked by supra-maximal stimulation proximal and distal to the block electrodes. Each animal of the randomized study received at least 300 s (range: 318-1563 s) of cumulative dc to investigate the impact of combined KHFAC + CBDC on nerve viability. Main results. The peak onset force was reduced significantly from 20.73 N (range: 18.6-26.5 N) with KHFAC alone to 0.45 N (range: 0.2-0.7 N) with the combined CBDC and KHFAC block waveform (p < 0.001). The area under the force curve was reduced from 6.8 Ns (range: 3.5-21.9 Ns) to 0.54 Ns (range: 0.18-0.86 Ns) (p < 0.01). No change in nerve conductivity was observed after application of the combined KHFAC + CBDC block relative to KHFAC waveforms. Significance. The distal application of CBDC can significantly reduce or even completely prevent the KHFAC onset response without a change in nerve conductivity.

Probing the interior of a solid volume with time reversal and nonlinear elastic wave spectroscopy.

PubMed

Le Bas, P Y; Ulrich, T J; Anderson, B E; Guyer, R A; Johnson, P A

2011-10-01

A nonlinear scatterer is simulated in the body of a sample and demonstrates a technique to locate and define the elastic nature of the scatterer. Using the principle of time reversal, elastic wave energy is focused at the interface between blocks of optical grade glass and aluminum. Focusing of energy at the interface creates nonlinear wave scattering that can be detected on the sample perimeter with time-reversal mirror elements. The nonlinearly generated scattered signal is bandpass filtered about the nonlinearly generated components, time reversed and broadcast from the same mirror elements, and the signal is focused at the scattering location on the interface. © 2011 Acoustical Society of America

Modulation of channel activity and gadolinium block of MscL by static magnetic fields.

PubMed

Petrov, Evgeny; Martinac, Boris

2007-02-01

The magnetic field of the Earth has for long been known to influence the behaviour and orientation of a variety of living organisms. Experimental studies of the magnetic sense have, however, been impaired by the lack of a plausible cellular and/or molecular mechanism providing meaningful explanation for detection of magnetic fields by these organisms. Recently, mechanosensitive (MS) ion channels have been implied to play a role in magnetoreception. In this study we have investigated the effect of static magnetic fields (SMFs) of moderate intensity on the activity and gadolinium block of MscL, the bacterial MS channel of large conductance, which has served as a model channel to study the basic physical principles of mechanosensory transduction in living cells. In addition to showing that direct application of the magnetic field decreased the activity of the MscL channel, our study demonstrates for the first time that SMFs can reverse the effect of gadolinium, a well-known blocker of MS channels. The results of our study are consistent with a notion that (1) the effects of SMFs on the MscL channels may result from changes in physical properties of the lipid bilayer due to diamagnetic anisotropy of phospholipid molecules and consequently (2) cooperative superdiamagnetism of phospholipid molecules under influence of SMFs could cause displacement of Gd(3+) ions from the membrane bilayer and thus remove the MscL channel block.

Multifunctional Nitrogen-Doped Loofah Sponge Carbon Blocking Layer for High-Performance Rechargeable Lithium Batteries.

PubMed

Gu, Xingxing; Tong, Chuan-Jia; Rehman, Sarish; Liu, Li-Min; Hou, Yanglong; Zhang, Shanqing

2016-06-29

Low-cost, long-life, and high-performance lithium batteries not only provide an economically viable power source to electric vehicles and smart electricity grids but also address the issues of the energy shortage and environmental sustainability. Herein, low-cost, hierarchically porous, and nitrogen-doped loofah sponge carbon (N-LSC) derived from the loofah sponge has been synthesized via a simple calcining process and then applied as a multifunctional blocking layer for Li-S, Li-Se, and Li-I2 batteries. As a result of the ultrahigh specific area (2551.06 m(2) g(-1)), high porosity (1.75 cm(3) g(-1)), high conductivity (1170 S m(-1)), and heteroatoms doping of N-LSC, the resultant Li-S, Li-Se, and Li-I2 batteries with the N-LSC-900 membrane deliver outstanding electrochemical performance stability in all cases, i.e., high reversible capacities of 623.6 mA h g(-1) at 1675 mA g(-1) after 500 cycles, 350 mA h g(-1) at 1356 mA g(-1) after 1000 cycles, and 150 mA h g(-1) at 10550 mA g(-1) after 5000 cycles, respectively. The successful application to Li-S, Li-Se, and Li-I2 batteries suggests that loofa sponge carbon could play a vital role in modern rechargeable battery industries as a universal, cost-effective, environmentally friendly, and high-performance blocking layer.

Naloxone Nasal Spray

MedlinePlus

... emergency medical treatment to reverse the life-threatening effects of a known or suspected opiate (narcotic) overdose. ... called opiate antagonists. It works by blocking the effects of opiates to relieve dangerous symptoms caused by ...

Reaction of Photochemically Generated Organic Cations with Colloidal Clays.

DTIC Science & Technology

1983-05-01

University of Notre Dame. IS. KEY WORDS (Continue on reverse aide if neceary end identify by block number) Chemistry of colloidal montmorillonite Absorption...Centlws m ftves n N mee.iy mi Identify by block number) Qi Organic radical cations will dimerize when adsorbed to the surface D of montmorillonite in...1 The Nature and Chemistry of Micelles .... 2 The Nature and Chemistry of Clay Minerals 5 Montmorillonite Catalyzed Color

Report on: Connecticut River Streambank Erosion Study, Massachusetts, New Hampshire and Vermont

DTIC Science & Technology

1979-11-01

Plastic filter cloths are used with considerable success beneath tiprap and other revetment materials such as articulated concrete blocks . The...rihutior unlimited II. SUPPLEMENTARY NOTES It. KEY WORDS (Continue on fever&e elde ifneceeeery and identify by block number). alluvial channel...erosion boat waves shear stress rock riprap lower bank erosion revetments flow control vegetation 20. ABSTRACT (Continue on reverse aide if neceesary and

Subcaliber Guns

DTIC Science & Technology

1988-06-16

310-6 11. TITLE (Include Security Classification) "SUBCALIBER GUNS " 12. PERSONAL AUTHOR(S) 13a. TYPE OF REPORT 13b. TIME COVERED 14. DATE OF REPORT...necessary and identify by block number) FIELD GROUP SUB-GROUP 4Large caliber weapons, .,Subcaliber guns (" J-) Parent weapons.; Small caliber weapons’y...19, ABSTRACT (Continue on reverse if necessary and identify by block number) Provides procedures for determining the suitability of subcaliber guns

Gas Source Molecular Beam Epitaxial Growth of GaN

DTIC Science & Technology

1992-11-25

identify by block number) FIELW GROUP SUB-GROUP 19. ABSTRACT (Continue on reverse if necessary and Identify by block number) Aluminum gallium nitride (AlGaN...AND TASK OBJECTIVES Aluminum gallium nitride (AIGaN) has long been recognized as a promising radiation hard optoelectronic material. AIGaN has a wide...Efficient, pure, low temperature sources for the gas source molecular beam epitaxial (GSMBE) growth of aluminum gallium nitride will essentially

Linear ablation of right atrial free wall flutter: demonstration of bidirectional conduction block as an endpoint associated with long-term success.

PubMed

Snowdon, Richard L; Balasubramaniam, Richard; Teh, Andrew W; Haqqani, Haris M; Medi, Caroline; Rosso, Raphael; Vohra, Jitendra K; Kistler, Peter M; Morton, Joseph B; Sparks, Paul B; Kalman, Jonathan M

2010-05-01

Ablation for atypical atrial flutter (AFL) is often performed during tachycardia, with termination or noninducibility of AFL as the endpoint. Termination alone is, however, an inadequate endpoint for typical AFL ablation, where incomplete isthmus block leads to high recurrence rates. We assessed conduction block across a low lateral right atrial (RA) ablation line (LRA) from free wall scar to the inferior vena cava (IVC) or tricuspid annulus in 11 consecutive patients with atypical RA free wall flutter. LRA block was assessed following termination of AFL, by pacing from the ablation catheter in the low lateral RA posterior to the ablation line and recording the sequence and timing of activation anterior to the line with a duodecapole catheter, and vice versa for bidirectional block. LRA block resulted in a high to low activation pattern on the halo and a mean conduction time of 201 +/- 48 ms to distal halo. LRA conduction block was present in only 2 out of 6 patients after termination of AFL by ablation. Ablation was performed during sinus rhythm (SR) in 9 patients to achieve LRA conduction block. No recurrence of AFL was observed at long-term follow-up (22 +/- 12 months); 3 patients developed AF. Termination of right free wall flutter is often associated with persistent LRA conduction and additional radiofrequency ablation (RFA) in SR is usually required. Low RA pacing may be used to assess LRA conduction block and offers a robust endpoint for atypical RA free wall flutter ablation, which results in a high long-term cure rate.

The Influence of Charged Species on the Phase Behavior, Self-Assembly, and Electrochemical Performance of Block Copolymer Electrolytes

NASA Astrophysics Data System (ADS)

Thelen, Jacob Lloyd

One of the major barriers to expanding the capacity of large-scale electrochemical energy storage within batteries is the threat of a catastrophic failure. Catastrophic battery pack failure can be initiated by a defect within a single battery cell. If the failure of a defective battery cell is not contained, the damage can spread and subsequently compromise the integrity of the entire battery back, as well as the safety of those in its surroundings. Replacing the volatile, flammable liquid electrolyte components found in most current lithium ion batteries with a solid polymer electrolyte (SPE) would significantly improve the cell-level safety of batteries; however, poor ionic conductivity and restricted operating temperatures compared to liquid electrolytes have plagued the practical application of SPEs. Rather than competing with the performance of liquid electrolytes directly, our approach to developing SPEs relies on increasing electrolyte functionality through the use of block copolymer architectures. Block copolymers, wherein two or more chemically dissimilar polymer chains are covalently bound, have a propensity to microphase separate into nanoscale domains that have physical properties similar to those of each of the different polymer chains. For instance, the block copolymer, polystyrene-b-poly(ethylene oxide) (SEO), has often been employed as a solid polymer electrolyte because the nanoscale domains of polystyrene (PS) can provide mechanical reinforcement, while the poly(ethylene oxide) microphases can solvate and conduct lithium ions. Block copolymer electrolytes (BCEs) formed from SEO/salt mixtures result in a material with the bulk mechanical properties of a solid, but with the ion conducting properties of a viscoelastic fluid. The efficacy SEO-based BCEs has been demonstrated; the enhanced mechanical functionality provided by the PS domains resist the propagation of dendritic lithium structures during battery operation, thus enabling the use of a lithium metal anode. The increase in the specific energy of a battery upon replacing a graphite anode with lithium metal can offset the losses in performance due to the poor ion conduction of SPEs. However, BCEs that enable the use of a lithium anode and have improved performance would represent a major breakthrough for the development of high capacity batteries. The electrochemical performance of BCEs has a complex relationship with the nature of the microphase separated domains, which is not well-understood. The objective of this dissertation is to provide fundamental insight into the nature of microphase separation and self-assembly of block copolymer electrolytes. Specifically, I will focus on how the ion-polymer interactions within a diverse set of BCEs dictate nanostructure. Combining such insight with knowledge of how nanostructure influences ion motion will enable the rational design of new BCEs with enhanced performance and functionality. In order to facilitate the study of BCE nanostructure, synchrotron-based X-ray scattering techniques were used to study samples over a wide range of length-scales under conditions relevant to the battery environment. The development of the experimental aspects of the X-ray scattering techniques, as well as an improved treatment of scattering data, played a pivotal role in the success of this work. The dissemination of those developments will be the focus of the first section. The thermodynamic impact of adding salt to a neutral diblock copolymer was studied in a model BCE composed of a low molecular weight SEO diblock copolymer mixed with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), a common salt used in lithium batteries. In neutral block copolymers (BCPs), self-assembly is a thermodynamically driven process governed by a balance between unfavorable monomer contacts and the entropy of mixing. When the enthalpic and entropic contributions to free energy are similar in magnitude, a block copolymer can undergo a thermally reversible phase transition from an ordered to a disordered nanostructure. We used temperature-dependent small angle X-ray scattering (SAXS) to observe this transition in the model SEO/LiTFSI system. Unlike neutral BCPs, which to a first approximation are single component systems, the SEO/LiTFSI system demonstrated the thermodynamically stable coexistence phases of ordered lamellae and disordered polymer over a finite temperature window. Analysis of the lamellar domains revealed an increase in salt concentration during the ODT, indicating local salt partitioning due to the presence of nanostructure. The performance of BCEs can also be improved by chemically functionalizing one of the polymer blocks by covalently attaching the salt anion. Since the cation is the only mobile species, these materials are coined single-ion conducting block copolymers. Single ion conduction can improve the efficiency of battery operation. In order for cation motion to occur in single-ion conducting block copolymers, it must dissociate from the backbone of the anion-containing polymer block. This direct coupling of ion dissociation (and hence conduction) and nanostructure has interesting implications for BCE performance. (Abstract shortened by ProQuest.).

Blocking-state influence on shot noise and conductance in quantum dots

NASA Astrophysics Data System (ADS)

Harabula, M.-C.; Ranjan, V.; Haller, R.; Fülöp, G.; Schönenberger, C.

2018-03-01

Quantum dots (QDs) investigated through electron transport measurements often exhibit varying, state-dependent tunnel couplings to the leads. Under specific conditions, weakly coupled states can result in a strong suppression of the electrical current, and they are correspondingly called blocking states. Using the combination of conductance and shot noise measurements, we investigate blocking states in carbon nanotube (CNT) QDs. We report negative differential conductance and super-Poissonian noise. The enhanced noise is the signature of electron bunching, which originates from random switches between the strongly and weakly conducting states of the QD. Negative differential conductance appears here when the blocking state is an excited state. In this case, at the threshold voltage where the blocking state becomes populated, the current is reduced. Using a master equation approach, we provide numerical simulations reproducing both the conductance and the shot noise pattern observed in our measurements.

FBCOT: a fast block coding option for JPEG 2000

NASA Astrophysics Data System (ADS)

Taubman, David; Naman, Aous; Mathew, Reji

2017-09-01

Based on the EBCOT algorithm, JPEG 2000 finds application in many fields, including high performance scientific, geospatial and video coding applications. Beyond digital cinema, JPEG 2000 is also attractive for low-latency video communications. The main obstacle for some of these applications is the relatively high computational complexity of the block coder, especially at high bit-rates. This paper proposes a drop-in replacement for the JPEG 2000 block coding algorithm, achieving much higher encoding and decoding throughputs, with only modest loss in coding efficiency (typically < 0.5dB). The algorithm provides only limited quality/SNR scalability, but offers truly reversible transcoding to/from any standard JPEG 2000 block bit-stream. The proposed FAST block coder can be used with EBCOT's post-compression RD-optimization methodology, allowing a target compressed bit-rate to be achieved even at low latencies, leading to the name FBCOT (Fast Block Coding with Optimized Truncation).

Universal Strategy To Reduce Noise Current for Sensitive Organic Photodetectors.

PubMed

Xiong, Sixing; Li, Lingliang; Qin, Fei; Mao, Lin; Luo, Bangwu; Jiang, Youyu; Li, Zaifang; Huang, Jinsong; Zhou, Yinhua

2017-03-15

Low noise current is critical for achieving high-detectivity organic photodetectors. Inserting charge-blocking layers is an effective approach to suppress the reverse-biased dark current. However, in solution-processed organic photodetectors, the charge-transport material needs to be dissolved in solvents that do not dissolve the underneath light-absorbing layer, which is not always possible for all kinds of light-absorbing materials developed. Here, we introduce a universal strategy of transfer-printing a conjugated polymer, poly(3-hexylthiophene) (P3HT), as the electron-blocking layer to realize highly sensitive photodetectors. The transfer-printed P3HT layers substantially and universally reduced the reverse-biased dark current by about 3 orders of magnitude for various photodetectors with different active layers. These photodetectors can detect the light signal as weak as several picowatts per square centimeter, and the device detectivity is over 10 12 Jones. The results suggest that the strategy of transfer-printing P3HT films as the electron-blocking layer is universal and effective for the fabrication of sensitive organic photodetectors.

Self-assembly approach toward magnetic silica-type nanoparticles of different shapes from reverse block copolymer mesophases.

PubMed

Garcia, Carlos B W; Zhang, Yuanming; Mahajan, Surbhi; DiSalvo, Francis; Wiesner, Ulrich

2003-11-05

In the present study poly(isoprene-block-ethylene oxide), PI-b-PEO, block copolymers are used to structure iron oxide and silica precursors into reverse mesophases, which upon dissolution of the organic matrix lead to well-defined nanoparticles of spheres, cylinders, and plates based on the original structure of the mesophase prepared. The hybrid mesophases with sphere, cylinder, and lamellar morphologies containing the inorganic components in the minority phases are characterized through a combination of small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), and electron energy loss spectroscopy (EELS). After heat treatments the respective nanoparticles on mica surfaces are characterized by scanning force microscopy (SFM). X-ray diffraction (XRD) and superconducting quantum interference device (SQUID) magnetometer measurements are performed to demonstrate that the heat treatment leads to the formation of a magnetic gamma-Fe2O3 crystalline phase within the amorphous aluminosilicate. The results pave the way to functional, i.e., magnetic nanoparticles where the size, shape, and iron oxide concentration can be controlled opening a range of possible applications.

I-V curve hysteresis induced by gate-free charging of GaAs nanowires' surface oxide

NASA Astrophysics Data System (ADS)

Alekseev, P. A.; Geydt, P.; Dunaevskiy, M. S.; Lähderanta, E.; Haggrén, T.; Kakko, J.-P.; Lipsanen, H.

2017-09-01

The control of nanowire-based device performance requires knowledge about the transport of charge carriers and its limiting factors. We present the experimental and modeled results of a study of electrical properties of GaAs nanowires (NWs), considering their native oxide cover. Measurements of individual vertical NWs were performed by conductive atomic force microscopy (C-AFM). Experimental C-AFM observations with numerical simulations revealed the complex resistive behavior of NWs. A hysteresis of current-voltage characteristics of the p-doped NWs as-grown on substrates with different types of doping was registered. The emergence of hysteresis was explained by the trapping of majority carriers in the surface oxide layer near the reverse-biased barriers under the source-drain current. It was found that the accumulation of charge increases the current for highly doped p+-NWs on n+-substrates, while for moderately doped p-NWs on p+-substrates, charge accumulation decreases the current due to blocking of the conductive channel of NWs.

Effect of hydrocortisone on cell morphology in C6 cells: the role of microfilaments in the inductive process. [Cytochalasin B; glycerol phosphate dehydrogenase

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

Berliner, J.A.; Bennett, K.; de Vellis, J.

Hydrocortisone induced cell spreading and the formation of microfilaments in C6 cells with a time course similar to that found for the induction of GPDH. Cytochalasin B caused a rapid and reversible cell rounding and microfilament breakdown. Breakdown of both sheath and network microfilaments occurred within 1 hour; after removal of cytochalasin B, reversal of morphological effects began within 30 min. High calcium was found to block reversal of the cytochalasin B induced alteration, but did not affect shape or microfilaments in non-cytochalasin B treated cells. It is concluded that since microfilament induction occurs late and the block in synthesismore » of GPDH by cytochalasin B occurs within hours after addition, microfilaments induced by hydrocortisone are probably not important in the sequence of events leading to GPDH induction. But, however, microfilaments present in uninduced cells may be important in the sequence of GPDH induction, since treatment with cytochalasin B rapidly breaks these down and also inhibits GPDH induction by hydrocortisone.« less

Reversal of neuromuscular blockade with sugammadex or neostigmine/atropine: Effect on postoperative gastrointestinal motility.

PubMed

Sen, A; Erdivanli, B; Tomak, Y; Pergel, A

2016-08-01

To compare sugammadex with conventional reversal of neuromuscular block in terms of postoperative gastrointestinal motility. Double blinded, randomized, controlled clinical trial. Operating room, postoperative recovery area. Seventy-two patients with ASA physical status I or II, scheduled for total thyroid surgery were studied. When 4 twitches were observed on train-of-four stimulation, neuromuscular block was reversed conversatively in the control group, and with sugammadex in the study group. Time to first flatus and feces, incidence of postoperative nausea, vomiting, diarrhea and constipation were collected. Median time of first flatus was 24 hours (18-32 [10-36]) in the neostigmine group, and 24 (18-28 [12-48]) in the sugammadex group (P > .05). Median (IQR) time of first feces was 24 hours (18-36 [10-48]) in neostigmine group, 32 hours (28-36 [12-72]) in sugammadex group (P > .05). There were no occurrences of nausea, vomiting, diarrhea, or constipation. Sugammadex may be safely used in cases where postoperative ileus is expected. Copyright © 2016 Elsevier Inc. All rights reserved.

The Impact of the Built Environment on Children's School Conduct Grades: The Role of Diversity of Use in a Hispanic Neighborhood

PubMed Central

Szapocznik, José; Lombard, Joanna; Martinez, Frank; Mason, Craig A.; Gorman-Smith, Deborah; Plater-Zyberk, Elizabeth; Brown, Scott C.; Spokane, Arnold

2013-01-01

A population-based study examined the relationship between diversity of use of the built environment and teacher reports of children's grades. Diversity of use of the built environment (i.e., proportion of a block that is residential, institutional, commercial and vacant) was assessed for all 403 city blocks in East Little Havana, Miami—a Hispanic neighborhood. Cluster analysis identified three block-types, based on diversity of use: Residential, Mixed-Use, and Commercial. Cross-classified hierarchical linear modeling was used to examine the impact of diversity of use, school, gender, and year-in-school on academic and conduct grades for 2857 public school children who lived in these blocks. Contrary to popular belief, mixed-use blocks were associated with optimal outcomes. Specifically, follow-up analyses found that a youth living on a residential block had a 74% greater odds of being in the lowest 10% of conduct grades (conduct GPA <2.17) than a youth living on a mixed-use block. In fact, an analysis of the population attributable fraction suggests that if the risk associated with residential blocks could be reduced to the level of risk associated with mixed-use blocks, a 38% reduction in Conduct GPAs <2.17 could be achieved in the total population. These findings suggest that public policy targeting the built environment may be a mechanism for community-based interventions to enhance children's classroom conduct, and potentially related sequelae. PMID:16967342

Block copolymer micelles as switchable templates for nanofabrication.

PubMed

Krishnamoorthy, Sivashankar; Pugin, Raphaël; Brugger, Juergen; Heinzelmann, Harry; Hoogerwerf, Arno C; Hinderling, Christian

2006-04-11

Block copolymer inverse micelles from polystyrene-block-poly-2-vinylpyridine (PS-b-P2VP) deposited as monolayer films onto surfaces show responsive behavior and are reversibly switchable between two states of different topography and surface chemistry. The as-coated films are in the form of arrays of nanoscale bumps, which can be transformed into arrays of nanoscale holes by switching through exposure to methanol. The use of these micellar films to act as switchable etch masks for the structuring of the underlying material to form either pillars or holes depending on the switching state is demonstrated.

Facile synthesis of main-chain degradable block copolymers for performance enhanced dismantlable adhesion.

PubMed

Sato, Eriko; Hagihara, Takashi; Matsumoto, Akikazu

2012-04-01

Block copolymers consisting of readily degradable polyperoxides and non-degradable vinyl polymers as the block segments were successfully synthesized by reversible chain transfer catalyzed polymerization, which is one of living radical polymerization techniques. The block copolymers showed characteristic morphology and wettability being different from the polymer blends. When block copolymers containing polyperoxide and polymethacrylate blocks were heated below 150 °C, the polyperoxide blocks were completely degraded and the polymethacrylate blocks were recovered without degradation. Block copolymers containing a poly(2-ethylhexyl methacrylate) block were then investigated as a dismantlable adhesion material, which requires adequate bonding strength during use and easy debonding on demand. Among the several block copolymers, the one consisting of poly(2-ethylhexyl methacrylate) and polyperoxide from methyl sorbate (PPMS) (M(n) = 4900) exhibited good performance as a pressure-sensitive adhesive (PSA). After heating the test specimens in a temperature range from 60 to 100 °C, PSA performance, which was evaluated by 180° peel strength and shear holding power measurements, was significantly diminished. Especially, after heating at 100 °C for 1 h, spontaneous debonding of some test specimens was observed because of the evolution of volatile acetaldehyde from PPMS.

Recovery of muscle function after deep neuromuscular block by means of diaphragm ultrasonography and adductor of pollicis acceleromyography with comparison of neostigmine vs. sugammadex as reversal drugs: study protocol for a randomized controlled trial.

PubMed

Cappellini, Iacopo; Picciafuochi, Fabio; Ostento, Daniele; Danti, Ginevra; De Gaudio, Angelo Raffaele; Adembri, Chiara

2018-02-21

The extensive use of neuromuscular blocking agents (NMBAs) during surgical procedures still leads to potential residual paralyzing effects in the postoperative period. Indeed, neuromuscular monitoring in an intra-operative setting is strongly advocated. Acetylcholinesterase inhibitors can reverse muscle block, but their short half-life may lead to residual curarization in the ward, especially when intermediate or long-acting NMBAs have been administered. Sugammadex is the first selective reversal drug for steroidal NMBAs; it has been shown to give full and rapid recovery of muscle strength, thus minimizing the occurrence of residual curarization. Acceleromyography of the adductor pollicis is the gold standard for detecting residual curarization, but it cannot be carried out on conscious patients. Ultrasonography of diaphragm thickness may reveal residual effects of NMBAs in conscious patients. This prospective, double-blind, single-center randomized controlled study will enroll patients (of American Society of Anesthesiologists physical status I-II, aged 18-80 years) who will be scheduled to undergo deep neuromuscular block with rocuronium for ear, nose, or throat surgery. The study's primary objective will be to compare the effects of neostigmine and sugammadex on postoperative residual curarization using two different tools: diaphragm ultrasonography and acceleromyography of the adductor pollicis. Patients will be extubated when the train-of-four ratio is > 0.9. Diaphragm ultrasonography will be used to evaluate the thickening fraction, which is the difference between the end expiratory thickness and the end inspiratory thickness, normalized to the end expiratory thickness. Ultrasonography will be performed before the initiation of general anesthesia, before extubation, and 10 and 30 min after discharging patients from the operating room. The secondary objective will be to compare the incidence of postoperative complications due to residual neuromuscular block between patients who receive neostigmine and those who receive sugammadex. Postoperative residual curarization is a topic of paramount importance, because its occurrence can cause complications and increase the length of stay in hospital and the related costs. Diaphragm ultrasound assessment may become a bedside integrative tool in the neuromuscular monitoring field to detect concealed residual curarization in surgical patients who have received paralyzing agents. EudraCT, 2013-004787-62. Registered on 18 June 2014, as "Evaluation of muscle function recovery after deep neuromuscular blockade by acceleromyography of the adductor pollicis or diaphragmatic echography: comparison between sugammadex and neostigmine." ClinicalTrials.gov, NCT02698969 . Registered on 15 February 2016, as "Recovery of Muscle Function After Deep Neuromuscular Block by Means of Diaphragm Ultrasonography and Adductor Pollicis Acceleromyography: Comparison of Neostigmine vs. Sugammadex as Reversal Drugs."

Development of Novel PD1/PD-L1 Antagonists Using Circular Cys-Knotted Micro Proteins

DTIC Science & Technology

2017-06-01

positive bacte- ria.[67] Similar antibacterial activities have been found in cyclo- tides isolated from Hedyota biflora (Rubiaceae family)[68] and C...immune control. Hence, reversing the inhibition of the adaptive immunity can lead to the activation of a patient’s immunity. For example, inhibition of...receptor and PD-L1, to block immune checkpoints, and facilitate antitumor activity . These checkpoint-blocking antibodies have demonstrated clinical

Circadian Variation in Host Defense.

DTIC Science & Technology

1987-05-21

block fevers by Inhibiting the production of prostaglandins of the E series (PGE) In the hypothalamus , our data suggest to us that there is a circadian...Continue on reverse if necessary and identify by block number) FIELD GROUP SUB-GROUP Key words: Interleukin-l, fever , circadian, rhythm, 08 body...to a rhythm in the thermoregulatory "set-point". The overall goal of our research was to determine whether this represents a circadian " fever ". If

Rare case of left-dominant arrhythmogenic right ventricular cardiomyopathy with dramatic reverse remodeling after cardiac resynchronization as an adjunct to pharmacological therapy.

PubMed

Hsiao, Chih-Chung; Kuo, Jen-Yuan; Yun, Chun-Ho; Hung, Chung-Lieh; Tsai, Cheng-Ho; Yeh, Hung-I

2012-01-01

A 57-year-old man presented with near syncope and hemodynamic compromise after exercise. A sustained ventricular tachycardia (VT) of right bundle-branch block morphology was evident upon examination at our emergency department. Baseline 12-lead electrocardiography revealed a sinus rhythm with a complete left bundle-branch block after successful cardioversion of the VT. Coronary angiography revealed patent coronary arteries, whereas left ventriculography demonstrated impaired systolic function, accompanied by a peculiar basal lateral aneurysm. Both echocardiography and magnetic resonance imaging were consistent with a diagnosis of left-dominant arrhythmogenic right ventricular cardiomyopathy. Four months later, substantial ventricular reverse remodeling and clinical improvements were observed after cardiac resynchronization therapy with a defibrillator, as an adjunct to conventional pharmacological therapy. Copyright © 2012 Elsevier Inc. All rights reserved.

Northeast Artificial Intelligence Consortium (NAIC) Review of Technical Tasks. Volume 2, Part 2.

DTIC Science & Technology

1987-07-01

A-A19 774 NORTHEAST ARTIFICIAL INTELLIGENCE CONSORTIUN (MIC) 1/5 YVIEN OF TEOICR. T.. (U) NORTHEAST ARTIFICIAL INTELLIGENCE CONSORTIUM SYRACUSE MY J...NORTHEAST ARTIFICIAL INTELLIGENCE CONSORTIUM (NAIC) *p,* ~ Review of Technical Tasks ,.. 12 PERSONAL AUTHOR(S) (See reverse) . P VI J.F. Allen, P.B. Berra...See reverse) /" I ABSTRACT (Coninue on ’.wrse if necessary and identify by block number) % .. *. -. ’ The Northeast Artificial Intelligence Consortium

Thermal Linear Expansion of Nine Selected AISI Stainless Steels

DTIC Science & Technology

1978-04-01

D. Desai and C. Y. Ho CINDAS REPORT 51 April 1978i! Prepared for AMERICAN IRON AND STEEL INSTITUTE d 1000 Sixteenth Street N.W. Washington, D.C...WORDS (Continue on reverse side it necessary and Identify by~ block number) *Thermal linear expansion ---*Stainless steels --- Iron -Nickel alloys... Iron -Chromium alloys 20fIStACT (Continue on reverse side it neceearyediett b lc ubr Thstechnical report reviews the available experimental data and

Let there be light: photo-cross-linked block copolymer nanoparticles.

PubMed

Roy, Debashish; Sumerlin, Brent S

2014-01-01

Polymeric nanoparticles are prepared by selectively cross-linking a photo-sensitive dimethylmaleimide-containing block of a diblock copolymer via UV irradiation. A well-defined photo-cross-linkable block copolymer is prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization of a dimethylmaleimide-functional acrylamido monomer containing photoreactive pendant groups with a poly(N,N-dimethylacrylamide) (PDMA) macro-chain transfer agent. The resulting amphiphilic block copolymers form micelles in water with a hydrophilic PDMA shell and a hydrophobic photo-cross-linkable dimethylmaleimide-containing core. UV irradiation results in photodimerization of the dimethylmaleimide groups within the micelle cores to yield core-cross-linked aggregates. Alternatively, UV irradiation of homogeneous solutions of the block copolymer in a non-selective solvent leads to in situ nanoparticle formation. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Highly Conductive Anion Exchange Block Copolymers

DTIC Science & Technology

We are developing a comprehensive fundamental understanding of the interplay between transport and morphology in newly synthesized hydroxide...conducting block copolymers. We are synthesizing hydroxide conducting block copolymers of various (1) morphology types, (2) ionic concentrations, and (3...ionic domain sizes. We are carefully characterizing the morphology and transport properties using both conventional and new advanced in situ techniques

Towards random matrix model of breaking the time-reversal invariance of elastic waves in chaotic cavities by feedback

NASA Astrophysics Data System (ADS)

Antoniuk, Oleg; Sprik, Rudolf

2010-03-01

We developed a random matrix model to describe the statistics of resonances in an acoustic cavity with broken time-reversal invariance. Time-reversal invariance braking is achieved by connecting an amplified feedback loop between two transducers on the surface of the cavity. The model is based on approach [1] that describes time- reversal properties of the cavity without a feedback loop. Statistics of eigenvalues (nearest neighbor resonance spacing distributions and spectral rigidity) has been calculated and compared to the statistics obtained from our experimental data. Experiments have been performed on aluminum block of chaotic shape confining ultrasound waves. [1] Carsten Draeger and Mathias Fink, One-channel time- reversal in chaotic cavities: Theoretical limits, Journal of Acoustical Society of America, vol. 105, Nr. 2, pp. 611-617 (1999)

Reversal of Pipecuronium-Induced Moderate Neuromuscular Block with Sugammadex in the Presence of a Sevoflurane Anesthetic: A Randomized Trial.

PubMed

Tassonyi, Edömér; Pongrácz, Adrienn; Nemes, Réka; Asztalos, László; Lengyel, Szabolcs; Fülesdi, Béla

2015-08-01

Pipecuronium is a steroidal neuromuscular blocking agent. Sugammadex, a relaxant binding γ-cyclodextrin derivative, reverses the effect of rocuronium, vecuronium, and pancuronium. We investigated whether sugammadex reverses moderate pipecuronium-induced neuromuscular blockade (NMB) and the doses required to achieve reversal. This single-center, randomized, double-blind, 5-group parallel-arm study comprised 50 patients undergoing general anesthesia with propofol, sevoflurane, fentanyl, and pipecuronium. Neuromuscular monitoring was performed with acceleromyography (TOF-Watch SX) according to international standards. When the NMB recovered spontaneously to train-of-four count 2, patients randomly received 1.0, 2.0, 3.0, or 4.0 mg/kg of sugammadex or placebo. Recovery time from sugammadex injection to normalized train-of-four (TOF) ratio 0.9 was the primary outcome variable. The recovery time from the sugammadex injection to final T1 was the secondary end point. Postoperative neuromuscular functions were also assessed. Each patient who received sugammadex recovered to a normalized TOF ratio of 0.9 within 5.0 minutes (95% lower confidence interval for the lowest dose 70.1%; for all doses 90.8%) and 79% of these patients reached a normalized TOF ratio 0.9 within 2.0 minutes (95% lower confidence interval for the lowest dose 26.7%; for all doses 63.7%). T1 recovered several minutes after the TOF ratio. No residual postoperative NMB was observed. Sugammadex adequately and rapidly reverses pipecuronium-induced moderate NMB during sevoflurane anesthesia. Once the train-of-four count has spontaneously returned to 2 responses following pipecuronium administration, a dose of 2.0 mg/kg of sugammadex is sufficient to reverse the NMB.

Sodium-bicarbonate cotransport in retinal Müller (glial) cells of the salamander.

PubMed

Newman, E A

1991-12-01

An electrogenic Na+/HCO3- cotransport system was studied in freshly dissociated Müller cells of the salamander retina. Cotransporter currents were recorded from isolated cells using the whole-cell, voltage-clamp technique following the block of K+ conductance with external Ba2+ and internal Cs+. At constant pHo, an outward current was evoked when extracellular HCO3- concentration was raised by pressure ejecting a HCO3(-)-buffered solution onto the surface of cells bathed in nominally HCO3(-)-free solution. The HCO3(-)-evoked outward current was reduced to 4.4% of control by 0.5 mM DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulfonate), to 28.8% of control by 2 mM DNDS (4,4'-dinitrostilbene-2,2'-disulfonate), and to 28.4% of control by 2 mM harmaline. Substitution of choline for Na+ in bath and ejection solutions reduced the response to 1.3% of control. Bicarbonate-evoked currents of normal magnitude were recorded when methane sulfonate was substituted for Cl- in bath, ejection, and intracellular solutions. Similarly, an outward current was evoked when extracellular Na+ concentration was raised in the presence of HCO3-. The Na(+)-evoked response was reduced to 16.2% of control by 2 mM DNDS and was abolished by removal of HCO3- from bath and ejection solutions. Taken together, these results (block by stilbenes and harmaline, HCO3- and Na+ dependence, Cl- independence) indicate that salamander Müller cells possess an electrogenic Na+/HCO3- cotransport system. Na+/HCO3- cotransporter sites were localized primarily at the endfoot region of Müller cells. Ejection of HCO3- onto the endfoot evoked outward currents 10 times larger than currents evoked by ejections onto the opposite (distal) end of the cell. The reversal potential of the cotransporter was determined by DNDS block of cotransport current. In the absence of a transmembrane HCO3- gradient, the reversal potential varied systematically as a function of the transmembrane Na+ gradient. The reversal potential was -0.1 mV for a [Na+]o:[Na+]i ratio of 1:1 and -25.2 mV for a Na+ gradient ratio of 7.4:1. Based on these values, the estimated stoichiometry of the cotransporter was 2.80 +/- 0.13:1 (HCO3-:Na+). Possible functions of the glial cell Na+/HCO3- cotransporter, including the regulation of CO2 in the retina and the regulation of cerebral blood flow, are discussed.

Block Copolymers: Synthesis and Applications in Nanotechnology

NASA Astrophysics Data System (ADS)

Lou, Qin

This study is focused on the synthesis and study of (block) copolymers using reversible deactivation radical polymerizations (RDRPs), including atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain transfer (RAFT) polymerization. In particular, two primary areas of study are undertaken: (1) a proof-of-concept application of lithographic block copolymers, and (2) the mechanistic study of the deposition of titania into block copolymer templates for the production of well-ordered titania nanostructures. Block copolymers have the ability to undergo microphase separation, with an average size of each microphase ranging from tens to hundreds of nanometers. As such, block copolymers have been widely considered for nanotechnological applications over the past two decades. The development of materials for various nanotechnologies has become an increasingly studied area as improvements in many applications, such as those found in the semiconductor and photovoltaic industries are constantly being sought. Significant growth in developments of new synthetic methods ( i.e. RDRPs) has allowed the production of block copolymers with molecular (and sometimes atomic) definition. In turn, this has greatly expanded the use of block copolymers in nanotechnology. Herein, we describe the synthesis of statistical and block copolymers of 193 nm photolithography methacrylate and acrylate resist monomers with norbornyl and adamantyl moieties using RAFT polymerization.. For these resist (block) copolymers, the phase separation behaviors were examined by atomic force microscopy (AFM). End groups were removed from the polymers to avoid complications during the photolithography since RAFT end groups absorb visible light. Poly(glycidyl methacrylate-block-polystyrene) (PGMA-b-PS) was synthesize by ATRP and demonstrated that this block copolymer acts as both a lithographic UV (365 nm) photoresist and a self-assembly material. The PGMA segments can undergo cationic ring-opening crosslinking and can act as a negative-tone photoresist. The PGMA-b-PS thin films were also studied for phase separation with ˜25 nm patterns using transmission electron microscopy (TEM). Poly(styrene-block-4-vinyl pyridine) (PS-b-P4VP) block copolymer thin films are shown to form perpendicular cylinder phase separated structures, and these may be used to template the formation of ordered titania nanostructures with sub-50 nm diameters on either silicon or indium tin oxide (ITO) substrates. A study of the mechanism of TiO2 formation within the P4VP cylinder phase was developed and tested. It was found that the titania nanostructure morphology is affected by pH and deposition temperatures, and successful deposition required the cross-linking of the P4VP phase in order to obtain individual nanostructures.

Sugammadex for reversal of neuromuscular blockade: a retrospective analysis of clinical outcomes and cost-effectiveness in a single center.

PubMed

Carron, Michele; Baratto, Fabio; Zarantonello, Francesco; Ori, Carlo

2016-01-01

The aim of the study is to evaluate the clinical and economic impact of introducing a rocuronium-neostigmine-sugammadex strategy into a cisatracurium-neostigmine regimen for neuromuscular block (NMB) management. We conducted a retrospective analysis of clinical outcomes and cost-effectiveness in five operating rooms at University Hospital of Padova. A clinical outcome evaluation after sugammadex administration as first-choice reversal drug in selected patients (rocuronium-sugammadex) and as rescue therapy after neostigmine reversal (rocuronium-neostigmine-sugammadex) compared to control was performed. A cost-analysis of NMB management accompanying the introduction of a rocuronium-neostigmine-sugammadex strategy into a cisatracurium-neostigmine regimen was carried out. To such purpose, two periods were compared: 2011-2012, without sugammadex available; 2013-2014, with sugammadex available. A subsequent analysis was performed to evaluate if sugammadex replacing neostigmine as first choice reversal drug is cost-effective. The introduction of a rocuronium-neostigmine-sugammadex strategy into a cisatracurium-neostigmine regimen reduced the average cost of NMB management by 36%, from €20.8/case to €13.3/case. Patients receiving sugammadex as a first-choice reversal drug (3%) exhibited significantly better train-of-four ratios at extubation (P<0.001) and were discharged to the surgical ward (P<0.001) more rapidly than controls. The cost-saving of sugammadex as first-choice reversal drug has been estimated to be €2.9/case. Patients receiving sugammadex as rescue therapy after neostigmine reversal (3.2%) showed no difference in time to discharge to the surgical ward (P=0.44) compared to controls. No unplanned intensive care unit (ICU) admissions with rocuronium-neostigmine-sugammadex strategy were observed. The potential economic benefit in avoiding postoperative residual curarization (PORC)-related ICU admission in the 2013-2014 period was estimated at an average value of €13,548 (€9,316-€23,845). Sugammadex eliminated PORC and associated morbidities. In our center, sugammadex reduced the costs of NMB management and promoted rapid turnover of patients in operating rooms, with total cost-effectiveness that counteracts the disadvantages of its high cost.

Effect of some blocking drugs on the pressor response to physostigmine in the rat

PubMed Central

Gokhale, S. D.; Gulati, O. D.; Joshi, N. Y.

1963-01-01

Bretylium and guanethidine blocked the pressor effect of physostigmine and potentiated the responses to adrenaline and noradrenaline on the blood pressure of the rat. Morphine and atropine in small doses blocked the pressor effect of physostigmine without interfering with the actions of adrenaline and noradrenaline. Chlorpromazine in small doses (0.5 to 2.5 mg/kg) blocked the pressor effect of physostigmine and potentiated the responses to noradrenaline whilst those to adrenaline remained unaltered. 3,6-Di(3-diethylaminopropoxy)pyridazine di(methiodide) (Win 4981) blocked the pressor effect of physostigmine and, in its early stages, this block was partially reversed by choline chloride. N-Diethylaminoethyl-N-isopentyl-N'N'-diisopropylurea (P-286), in a dose that reduced the effect of dimethylphenylpiperazinium, had no effect on the pressor response to physostigmine or on the responses to adrenaline and noradrenaline. Hexamethonium, even in large doses (100 mg/kg), only blocked partially the effect of physostigmine while mecamylamine produced a complete block; the responses to adrenaline and noradrenaline were potentiated in both instances. ImagesFig. 1Fig. 2Fig. 3Fig. 4Fig. 5Fig. 6 PMID:14081658

Assessment of exit block following pulmonary vein isolation: far-field capture masquerading as entrance without exit block.

PubMed

Vijayaraman, Pugazhendhi; Dandamudi, Gopi; Naperkowski, Angela; Oren, Jess; Storm, Randle; Ellenbogen, Kenneth A

2012-10-01

Complete electrical isolation of pulmonary veins (PVs) remains the cornerstone of ablation therapy for atrial fibrillation. Entrance block without exit block has been reported to occur in 40% of the patients. Far-field capture (FFC) can occur during pacing from the superior PVs to assess exit block, and this may appear as persistent conduction from PV to left atrium (LA). To facilitate accurate assessment of exit block. Twenty consecutive patients with symptomatic atrial fibrillation referred for ablation were included in the study. Once PV isolation (entrance block) was confirmed, pacing from all the bipoles on the Lasso catheter was used to assess exit block by using a pacing stimulus of 10 mA at 2 ms. Evidence for PV capture without conduction to LA was necessary to prove exit block. If conduction to LA was noticed, pacing output was decreased until there was PV capture without conduction to LA or no PV capture was noted to assess for far-field capture in both the upper PVs. All 20 patients underwent successful isolation (entrance block) of all 76 (4 left common PV) veins: mean age 58 ± 9 years; paroxysmal atrial fibrillation 40%; hypertension 70%, diabetes mellitus 30%, coronary artery disease 15%; left ventricular ejection fraction 55% ± 10%; LA size 42 ± 11 mm. Despite entrance block, exit block was absent in only 16% of the PVs, suggesting persistent PV to LA conduction. FFC of LA appendage was noted in 38% of the left superior PVs. FFC of the superior vena cava was noted in 30% of the right superior PVs. The mean pacing threshold for FFC was 7 ± 4 mA. Decreasing pacing output until only PV capture (loss of FFC) is noted was essential to confirm true exit block. FFC of LA appendage or superior vena cava can masquerade as persistent PV to LA conduction. A careful assessment for PV capture at decreasing pacing output is essential to exclude FFC. Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Equilibrium potential for the postsynaptic response in the squid giant synapse.

PubMed

Llinás, R; Joyner, R W; Nicholson, C

1974-11-01

The reversal potential for the EPSP in the squid giant synapse has been studied by means of an intracellular, double oil gap technique. This method allows the electrical isolation of a portion of the axon from the rest of the fiber and generates a quasi-isopotential segment. In order to make the input resistance of this nerve segment as constant as possible, the electroresponsive properties of the nerve membrane were blocked by intracellular injection of tetraethylammonium (TEA) and local extracellular application of tetrodotoxin (TTX). Thus, EPSP's could be evoked in the isolated segment with a minimal amount of electroresponsive properties. The reversal potential for the EPSP (EEPSP) was measured by recording the synaptic potential or the synaptic current during voltage clamping. The results indicate that EEPSP may vary from +15 to +25 mV, which is more positive than would be expected for a 1:1 conductance change for Na(+) and K(+) (approximately -15 mV) and too negative for a pure Na(+) conductance ((+)40 mV). This latter value (E(Na)) was directly determined in the voltage clamp experiments. The results suggest that the synaptic potential is probably produced by a permeability change to Na(+) to K(+) in a 4:1 ratio. No change in time-course was observed in the synaptic current at clamp levels of -100 and +90 mV. The implications of a variable ratio for Na(+)-K(+) permeability in subsynaptic-postsynaptic membranes are discussed.

Perpendicularly Aligned, Anion Conducting Nanochannels in Block Copolymer Electrolyte Films

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

Arges, Christopher G.; Kambe, Yu; Suh, Hyo Seon

Connecting structure and morphology to bulk transport properties, such as ionic conductivity, in nanostructured polymer electrolyte materials is a difficult proposition because of the challenge to precisely and accurately control order and the orientation of the ionic domains in such polymeric films. In this work, poly(styrene-block-2-vinylpyridine) (PSbP2VP) block copolymers were assembled perpendicularly to a substrate surface over large areas through chemical surface modification at the substrate and utilizing a versatile solvent vapor annealing (SVA) technique. After block copolymer assembly, a novel chemical vapor infiltration reaction (CVIR) technique selectively converted the 2-vinylpyridine block to 2-vinyl n-methylpyridinium (NMP+ X-) groups, which aremore » anion charge carriers. The prepared block copolymer electrolytes maintained their orientation and ordered nanostructure upon the selective introduction of ion moieties into the P2VP block and post ion-exchange to other counterion forms (X- = chloride, hydroxide, etc.). The prepared block copolymer electrolyte films demonstrated high chloride ion conductivities, 45 mS cm(-1) at 20 degrees C in deionized water, the highest chloride ion conductivity for anion conducting polymer electrolyte films. Additionally, straight-line lamellae of block copolymer electrolytes were realized using chemoepitaxy and density multiplication. The devised scheme allowed for precise and accurate control of orientation of ionic domains in nanostructured polymer electrolyte films and enables a platform for future studies that examines the relationship between polymer electrolyte structure and ion transport.« less

Novel Neurostimulation of Autonomic Pelvic Nerves Overcomes Bladder-Sphincter Dyssynergia

PubMed Central

Peh, Wendy Yen Xian; Mogan, Roshini; Thow, Xin Yuan; Chua, Soo Min; Rusly, Astrid; Thakor, Nitish V.; Yen, Shih-Cheng

2018-01-01

The disruption of coordination between smooth muscle contraction in the bladder and the relaxation of the external urethral sphincter (EUS) striated muscle is a common issue in dysfunctional bladders. It is a significant challenge to overcome for neuromodulation approaches to restore bladder control. Bladder-sphincter dyssynergia leads to undesirably high bladder pressures, and poor voiding outcomes, which can pose life-threatening secondary complications. Mixed pelvic nerves are potential peripheral targets for stimulation to treat dysfunctional bladders, but typical electrical stimulation of pelvic nerves activates both the parasympathetic efferent pathway to excite the bladder, as well as the sensory afferent pathway that causes unwanted sphincter contractions. Thus, a novel pelvic nerve stimulation paradigm is required. In anesthetized female rats, we combined a low frequency (10 Hz) stimulation to evoke bladder contraction, and a more proximal 20 kHz stimulation of the pelvic nerve to block afferent activation, in order to produce micturition with reduced bladder-sphincter dyssynergia. Increasing the phase width of low frequency stimulation from 150 to 300 μs alone was able to improve voiding outcome significantly. However, low frequency stimulation of pelvic nerves alone evoked short latency (19.9–20.5 ms) dyssynergic EUS responses, which were abolished with a non-reversible proximal central pelvic nerve cut. We demonstrated that a proximal 20 kHz stimulation of pelvic nerves generated brief onset effects at lower current amplitudes, and was able to either partially or fully block the short latency EUS responses depending on the ratio of the blocking to stimulation current. Our results indicate that ratios >10 increased the efficacy of blocking EUS contractions. Importantly, we also demonstrated for the first time that this combined low and high frequency stimulation approach produced graded control of the bladder, while reversibly blocking afferent signals that elicited dyssynergic EUS contractions, thus improving voiding by 40.5 ± 12.3%. Our findings support advancing pelvic nerves as a suitable neuromodulation target for treating bladder dysfunction, and demonstrate the feasibility of an alternative method to non-reversible nerve transection and sub-optimal intermittent stimulation methods to reduce dyssynergia. PMID:29618971

M-X Environmental Technical Report. Alternative Potential Operating Base Locations, Coyote Spring Valley.

DTIC Science & Technology

1980-12-22

necessary and identify by block number) MX Coyote Spring, Nevada Siting Analysis Nevada Environnental Report 20. ABSTRACT (Continue on reverse side If...necessary and Identify by block number) The area of analysis (AO) for the Coyote Spring Valley operating base option includes both Clark and Lincoln...counties, and is located in the southern portion of the designated region of influence. Las Vegas and the surrounding suburbs are the major settlements and

Book Analysis: Challenger: A Major Malfunction.

DTIC Science & Technology

1988-04-01

REPORT NUMBER 88-113S TITLE BOOK ANALYSIS: CHALLENGER : A MAJOR MALFUNCTION AUTHOR(S) MAJOR THOMAS M. HALL, USAF FACULTY ADVISOR LT COL JOhN R. GRELLMAN... CHALLENGER : A MAJOR MALFUNCTION 12. PERSONAL AUTHOR(S) Hall, Thomas M., Major, USAF 13a. TYPE OF REPORT 13b. TIME COVERED 14. DATE OF REPORT (Year, Month...identify by block number) FIELD GROUP SUB-GROUP 19. ABSTRACT Continue on reverse if necessary and identify by block number) This report analyzes Challenger

A Study of Secular and Tidal Tilt in Wyoming and Utah.

DTIC Science & Technology

1982-09-15

addition to storing the data from the tiltmeters at each site* . some of the dataloggers will be eq?,ioped with sensors to monitor atmospheric pressure and...WORDS (Continue en reverse side it neceeeary end identify by block number) Earth tides Tiltmeter Hydrofracture Tidal admittance .Ut 20. ABSTRACT...Contput-onreverse side if necessary and identify by block number) Q~ring the period .rvered by this report, we have used our 4porehole tiltmeter arrays to

Effect of PFDA on Cardiac Membrane Function.

DTIC Science & Technology

1983-03-01

NO. 3. RECIPIENT’S CATALOG NUMBER AFOS-TR - / .... 4. TITLE (and Subtitle) 5. TVPF nF REPORT & PERIOD COVERED EFFECT OF PFDA ON CARDIAC MEMBRANE...Continue on reverse side II necessary and Identify by block number) Heart, Thyroxine, Triiodothyronine, PFDA 0t C) 20, ABSTRACT (Continue on revereD...eide If neceesary and Identify by block number) LTJ "Yihe in vivo and in vitro heart rates of rats treated with 75 mg/kg PFDA was __j significantly

Blue light differentially represses mesophyll conductance in high vs low latitude genotypes of Populus trichocarpa Torr. & Gray.

PubMed

Momayyezi, Mina; Guy, Robert D

2017-06-01

To explore what role chloroplast positioning might have in relation to latitudinal variation in mesophyll conductance (g m ) of Populus trichocarpa Torr. & Gray (black cottonwood), we examined photosynthetic response to different blue light treatments in six representative genotypes (three northern and three southern). The proportion of blue (B) to red light was varied from 0:100, 10:90, 20:80, 40:60, and 60:40 while keeping the total photosynthetic photon flux density constant. Mesophyll conductance was estimated by monitoring chlorophyll fluorescence in combination with gas exchange. Compared to the control (10% B), g m was significantly lower with increasing blue light. Consistent with a change in chloroplast positioning, there was a simultaneous but reversible decrease in chlorophyll content index (CCI), as measured by foliar greenness, while the extracted, actual chlorophyll content (ACC) remained unchanged. Blue-light-induced decreases in g m and CCI were greater in northern genotypes than in southern genotypes, both absolutely and proportionally, consistent with their inherently higher photosynthetic rate. Treatment of leaves with cytochalasin D, an inhibitor of actin-based chloroplast motility, reduced both CCI and ACC but had no effect on the CCI/ACC ratio and fully blocked any effect of blue light on CCI. Cytochalasin D reduced g m by ∼56% under 10% B, but did not block the effect of 60% B on g m , which was reduced a further 20%. These results suggest that the effect of high blue light on g m is at least partially independent of chloroplast repositioning. High blue light reduced carbonic anhydrase activity by 20% (P<0.05), consistent with a possible reduction in protein-mediated facilitation of CO 2 diffusion. Copyright © 2017 Elsevier GmbH. All rights reserved.

Contextual effects on preattentive processing of sound motion as revealed by spatial MMN.

PubMed

Shestopalova, L B; Petropavlovskaia, E A; Vaitulevich, S Ph; Nikitin, N I

2015-04-01

The magnitude of spatial distance between sound stimuli is critically important for their preattentive discrimination, yet the effect of stimulus context on auditory motion processing is not clear. This study investigated the effects of acoustical change and stimulus context on preattentive spatial change detection. Auditory event-related potentials (ERPs) were recorded for stationary midline noises and two patterns of sound motion produced by linear or abrupt changes of interaural time differences. Each of the three types of stimuli was used as standard or deviant in different blocks. Context effects on mismatch negativity (MMN) elicited by stationary and moving sound stimuli were investigated by reversing the role of standard and deviant stimuli, while the acoustical stimulus parameters were kept the same. That is, MMN amplitudes were calculated by subtracting ERPs to identical stimuli presented as standard in one block and deviant in another block. In contrast, effects of acoustical change on MMN amplitudes were calculated by subtracting ERPs of standards and deviants presented within the same block. Preattentive discrimination of moving and stationary sounds indexed by MMN was strongly dependent on the stimulus context. Higher MMNs were produced in oddball configurations where deviance represented increments of the sound velocity, as compared to configurations with velocity decrements. The effect of standard-deviant reversal was more pronounced with the abrupt sound displacement than with gradual sound motion. Copyright © 2015 Elsevier B.V. All rights reserved.

Industrial Water Analysis Program: A Critical Study.

DTIC Science & Technology

1983-09-01

Patterson Air Force Base, Ohio UMAMUION lTATEMNT A APtO.6UPbhtd3WJ 83 11 04 014’ X. .. . INDUSTRIAL WATER ANALYSIS PROGRAM: A CRITICAL STUDY Dennis C...Twhoo-17 (ATC) Wright-FPafewon AFB O 44 3 1S. KEY WORDS (Continue on reverse aide if necessary and identify by block number) Industrial Water Analysis ...Boiler Water Analysis Preservation Procedures Air Force Industrial Water Stabilization Procedures 20. ABSTRACT (Continue on reverse side it necessary and

Wartime Tracking of Class I Surface Shipments from Production or Procurement to Destination

DTIC Science & Technology

1992-04-01

Armed Forces I ICAF-FAP National Defense University 6c. ADDRESS (City, State, ard ZIP Code ) 7b. ADDRESS (City, State, and ZIP Code ) Fort Lesley J...INSTRUMENT IDENTIFICATION NUMBER ORGANIZATION (If applicable) 9c. ADDRESS (City, State, and ZIP Code ) 10. SOURCE OF FUNDING NUMBERS PROGRAM PROJECT TASK...COSATI CODES 18. SUBJECT TERMS (Continue on reverse if necessary and identify by block number) FIELD GROUP SUB-GROUP 19. ABSTRACT (Continue on reverse

On-Site Fuel Cell Energy Systems: The U.S. Air Force Field Test Demonstration Plan.

DTIC Science & Technology

1980-12-01

Continue on reverse -, de if necessary and identify by block number) Fuel cells Cogererati on Energy conversion ABSTRACT (Continue an reverse ide If...fuel electrode, water at the oxygen electrode, and to act as a mechanical barrier between the two gases to prevent mixing and direct combustion . When the...possibility of more effective utilization of hydrocarbon fuels, especially when compared with the alternative heat engine combustion technologies. Figure 12

Observation of backscattering-immune chiral electromagnetic modes without time reversal breaking.

PubMed

Chen, Wen-Jie; Hang, Zhi Hong; Dong, Jian-Wen; Xiao, Xiao; Wang, He-Zhou; Chan, C T

2011-07-08

A strategy is proposed to realize robust transport in a time reversal invariant photonic system. Using numerical simulation and a microwave experiment, we demonstrate that a chiral guided mode in the channel of a three-dimensional dielectric layer-by-layer photonic crystal is immune to the scattering of a square patch of metal or dielectric inserted to block the channel. The chirality based robust transport can be realized in nonmagnetic dielectric materials without any external field.

Reversal of β-oxidative pathways for the microbial production of chemicals and polymer building blocks.

PubMed

Kallscheuer, Nicolai; Polen, Tino; Bott, Michael; Marienhagen, Jan

2017-07-01

β-Oxidation is the ubiquitous metabolic strategy to break down fatty acids. In the course of this four-step process, two carbon atoms are liberated per cycle from the fatty acid chain in the form of acetyl-CoA. However, typical β-oxidative strategies are not restricted to monocarboxylic (fatty) acid degradation only, but can also be involved in the utilization of aromatic compounds, amino acids and dicarboxylic acids. Each enzymatic step of a typical β-oxidation cycle is reversible, offering the possibility to also take advantage of reversed metabolic pathways for applied purposes. In such cases, 3-oxoacyl-CoA thiolases, which catalyze the final chain-shortening step in the catabolic direction, mediate the condensation of an acyl-CoA starter molecule with acetyl-CoA in the anabolic direction. Subsequently, the carbonyl-group at C3 is stepwise reduced and dehydrated yielding a chain-elongated product. In the last years, several β-oxidation pathways have been studied in detail and reversal of these pathways already proved to be a promising strategy for the production of chemicals and polymer building blocks in several industrially relevant microorganisms. This review covers recent advancements in this field and discusses constraints and bottlenecks of this metabolic strategy in comparison to alternative production pathways. Copyright © 2017 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

The interaction between hexamethonium and tubocurarine on the rat neuromuscular junction.

PubMed Central

Rang, H. P.; Rylett, R. J.

1984-01-01

The ability of hexamethonium (C6) to reverse the neuromuscular blocking action of tubocurarine (Tc) has been reinvestigated at the voltage clamped endplate of the omohyoid muscle of rat. The possibility that a weak anticholinesterase action of C6 could contribute to the paradoxical potentiation of the peak amplitude of the endplate response has been examined. C6 (50-200 microM) caused an increase in the amplitude of nerve-evoked endplate currents (e.p.cs) recorded in the presence of 0.6 microM Tc. The effect decreased with hyperpolarization of the muscle fibre. Irreversible inhibition of acetylcholinesterase resulted in a loss of the anti-curare effect of C6. C6 did not cause an increase in e.p.c. amplitude when acetylcholine (ACh) receptors were blocked irreversibly by alpha-bungaratoxin. When transmission was blocked by increased Mg2+ concentration, C6 (50-400 microM) reduced the amplitude of e.p.cs without appreciably affecting their time course. C6 caused a decrease in the amplitude of miniature endplate currents (m.e.p.cs) the effect being slightly increased when the fibre was hyperpolarized. An e-fold increase in the effectiveness of C6 occurred with approximately 58 mV hyperpolarization. High concentrations (greater than 400 microM) affected the time course of m.e.p.cs in a manner suggestive of open channel block, but this was not evident at 200 microM, the concentration that was most effective in reversing Tc block. When tested against responses to short ionophoretic pulses of agonists, C6 was less effective against ACh (EC50ca. 300 microM) than against carbachol (CCh) (EC50 100 microM). When cholinesterase was irreversibly inhibited, C6 blocked responses to both agonists equally (EC50ca. 100 microM). The effectiveness of C6 in blocking the action of CCh was reduced 10 fold in the presence of 0.6 microM Tc, implying that the two antagonists compete for the same binding site. C6 (50-200 microM) in the presence of Tc (0.6 microM) increased the response to ionophoretically applied ACh but not that to CCh. C6 was equipotent in blocking m.e.p.cs and responses to ionophoretically applied ACh whereas Tc was more potent against the exogenously applied agonist. C6 was a weak inhibitor of acetylcholinesterase activity in rat muscle homogenates (EC50 1.5 mM). The results are discussed in terms of the kinetic hypothesis advanced by Ginsborg & Stephenson (1974) to account for the Tc reversal phenomenon.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:6141831

Human Immunodeficiency Virus Type 1 (HIV-1) Integration: a Potential Target for Microbicides To Prevent Cell-Free or Cell-Associated HIV-1 Infection ▿

PubMed Central

Terrazas-Aranda, Katty; Van Herrewege, Yven; Hazuda, Daria; Lewi, Paul; Costi, Roberta; Di Santo, Roberto; Cara, Andrea; Vanham, Guido

2008-01-01

Conceptually, blocking human immunodeficiency virus type 1 (HIV-1) integration is the last possibility for preventing irreversible cellular infection. Using cocultures of monocyte-derived dendritic cells and CD4+ T cells, which represent primary targets in sexual transmission, we demonstrated that blocking integration with integrase strand transfer inhibitors (InSTIs), particularly L-870812, could consistently block cell-free and cell-associated HIV-1 infection. In a pretreatment setting in which the compound was present before and during infection and was afterwards gradually diluted during the culture period, the naphthyridine carboxamide L-870812 blocked infection with the cell-free and cell-associated HIV-1 Ba-L strain at concentrations of, respectively, 1,000 and 10,000 nM. The potency of L-870812 was similar to that of the nucleotide reverse transcriptase inhibitor R-9-(2-phosphonylmethoxypropyl) adenine (PMPA) but one or two orders of magnitude lower than those of the nonnucleoside reverse transcriptase inhibitors UC781 and TMC120. In contrast, the diketo acid RDS derivative InSTIs showed clear-cut but weaker antiviral activity than L-870812. Moreover, L-870812 completely blocked subtype C and CRFO2_AG primary isolates, which are prevalent in the African heterosexual epidemic. Furthermore, the addition of micromolar concentrations of L-870812 even 24 h after infection could still block both cell-free and cell-associated Ba-L, opening the prospect of postexposure prophylaxis. Finally, an evaluation of the combined activity of L-870812 with either T20, zidovudine, PMPA, UC781, or TMC120 against replication-deficient HIV-1 Ba-L (env) pseudovirus suggested synergistic activity for all combinations. Importantly, compounds selected for the study by using the coculture model were devoid of acute or delayed cytotoxic effects at HIV-blocking concentrations. Therefore, these findings provide evidence supporting consideration of HIV-1 integration as a target for microbicide development. PMID:18474579

RAFT Dispersion Alternating Copolymerization of Styrene with N-Phenylmaleimide: Morphology Control and Application as an Aqueous Foam Stabilizer

PubMed Central

2016-01-01

We report a new nonaqueous polymerization-induced self-assembly (PISA) formulation based on the reversible addition–fragmentation chain transfer (RAFT) dispersion alternating copolymerization of styrene with N-phenylmaleimide using a nonionic poly(N,N-dimethylacrylamide) stabilizer in a 50/50 w/w ethanol/methyl ethyl ketone (MEK) mixture. The MEK cosolvent is significantly less toxic than the 1,4-dioxane cosolvent reported previously [YangP.; Macromolecules2013, 46, 8545−8556]. The core-forming alternating copolymer block has a relatively high glass transition temperature (Tg), which leads to vesicular morphologies being observed during PISA, as well as the more typical sphere and worm phases. Each of these copolymer morphologies has been characterized by transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) studies. TEM studies reveal micrometer-sized elliptical particles with internal structure, with SAXS analysis suggesting an oligolamellar vesicle morphology. This structure differs from that previously reported for a closely related PISA formulation utilizing a poly(methacrylic acid) stabilizer block for which unilamellar platelet-like particles are observed by TEM and SAXS. This suggests that interlamellar interactions are governed by the nature of the steric stabilizer layer. Moreover, using the MEK cosolvent also enables access to a unilamellar vesicular morphology, despite the high Tg of the alternating copolymer core-forming block. This was achieved by simply conducting the PISA synthesis at a higher temperature for a longer reaction time (80 °C for 24 h). Presumably, MEK solvates the core-forming block more than the previously utilized 1,4-dioxane cosolvent, which leads to greater chain mobility. Finally, preliminary experiments indicate that the worms are much more efficient stabilizers for aqueous foams than either the spheres or the oligolamellar elliptical vesicles. PMID:27708458

Reverse leakage current characteristics of InGaN/GaN multiple quantum well ultraviolet/blue/green light-emitting diodes

NASA Astrophysics Data System (ADS)

Zhou, Shengjun; Lv, Jiajiang; Wu, Yini; Zhang, Yuan; Zheng, Chenju; Liu, Sheng

2018-05-01

We investigated the reverse leakage current characteristics of InGaN/GaN multiple quantum well (MQW) near-ultraviolet (NUV)/blue/green light-emitting diodes (LEDs). Experimental results showed that the NUV LED has the smallest reverse leakage current whereas the green LED has the largest. The reason is that the number of defects increases with increasing nominal indium content in InGaN/GaN MQWs. The mechanism of the reverse leakage current was analyzed by temperature-dependent current–voltage measurement and capacitance–voltage measurement. The reverse leakage currents of NUV/blue/green LEDs show similar conduction mechanisms: at low temperatures, the reverse leakage current of these LEDs is attributed to variable-range hopping (VRH) conduction; at high temperatures, the reverse leakage current of these LEDs is attributed to nearest-neighbor hopping (NNH) conduction, which is enhanced by the Poole–Frenkel effect.

The neuromuscular blocking properties of a series of bis-quaternary tropeïnes

PubMed Central

Haining, C. G.; Johnston, R. G.; Smith, J. M.

1960-01-01

Linkage of two tropine esters through their nitrogen atoms by the chain -[CH2]m-O-CO-[CH2]n-CO-O-[CH2]m-, in which m was 2 or 3 and n varied from 0 to 6, gave compounds which produced neuromuscular block without depolarization. Reversibility be neostigmine was confirmed for a few compounds. Potency was found to depend upon the tropine ester employed and upon the values of n and m. Short duration and hypotensive properties were favoured by the higher values of n. The duration of action of the compound based on the phenylacetic acid ester of tropine, in which n=4 and m=2, varied considerably in different species. Epimerization, in which the relative positions of the methyl group and the linking chain on the quaternary tropane nitrogen atom were reversed, did not produce subtances having more favourable properties than those possessed by the unepimerized compounds. PMID:14398886

Reverse pupillary block associated with pigment dispersion syndrome after in-the-bag intraocular lens implantation.

PubMed

Itagaki, Hideo; Kunikata, Toshio; Hiratsuka, Kentaro; Saito, Junichiro; Oshika, Tetsuro

2013-12-01

A 61-year-old man with high myopia who had received a systemic α1A-adrenoceptor antagonist had phacoemulsification and in-the-bag intraocular lens implantation in the right eye. One day postoperatively, marked pigment dispersion in the anterior chamber, posterior bowing of the iris, and iridodonesis were noted associated with a subsequent elevation in intraocular pressure (IOP). Pharmacological pupil dilation was effective in reducing pigment dispersion and IOP, and laser peripheral iridotomy was performed to alleviate posterior bowing of the iris. We hypothesize that dynamic changes in the aqueous humor flow by cataract surgery and latent flaccidity of the iris due to the systemic α1A-adrenoceptor antagonist caused reverse pupillary block. High myopia may be another risk factor for this complication. Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Tunable Encapsulation Structure of Block Copolymer Coated Single-Walled Carbon Nanotubes in Aqueous Solution

DOE PAGES

Han, Youngkyu; Ahn, Suk-Kyun; Zhang, Zhe; ...

2015-05-15

The nano-sized and shape-tunable molecular building blocks can provide great opportunities for the fabrication of precisely controlled nanostructures. In this work, we have fabricated a molecular building block of single-walled carbon nanotubes (SWNTs) coated by PPO-PEO-PPO block copolymers whose encapsulation structure can be controlled via temperature or addition of small molecules. The structure and optical properties of SWNT-block copolymers have been investigated by small angle neutron scattering (SANS), ultraviolet-visible (UV-vis) spectroscopy, atomic force microscopy (AFM), and molecular dynamics (MD) simulation. The structure of the hydrated block copolymer layer surrounding SWNT can be controlled reversibly by varying temperature as well asmore » by irreversibly adding 5-methylsalicylic acid (5MS). Increasing hydrophobicity of the polymers with temperature and strong tendency of 5MS to interact with both block copolymers and orbitals of the SWNTs are likely to be responsible for the significant structural change of the block copolymer encapsulation layer, from loose corona shell to tightly encapsulating compact shell. These result shows an efficient and simple way to fabricate and manipulate carbon-based nano building blocks in aqueous systems with tunable structure.« less

Thermoset coatings from epoxidized sucrose soyate and blocked, bio-based dicarboxylic acids.

PubMed

Kovash, Curtiss S; Pavlacky, Erin; Selvakumar, Sermadurai; Sibi, Mukund P; Webster, Dean C

2014-08-01

A new 100% bio-based thermosetting coating system was developed from epoxidized sucrose soyate crosslinked with blocked bio-based dicarboxylic acids. A solvent-free, green method was used to block the carboxylic acid groups and render the acids miscible with the epoxy resin. The thermal reversibility of this blocking allowed for the formulation of epoxy-acid thermoset coatings that are 100% bio-based. This was possible due to the volatility of the vinyl ethers under curing conditions. These systems have good adhesion to metal substrates and perform well under chemical and physical stress. Additionally, the hardness of the coating system is dependent on the chain length of the diacid used, making it tunable. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Functional and Multifunctional Polymers: Materials for Smart Structures

NASA Technical Reports Server (NTRS)

Arnold, S.; Pratt, L. M.; Li, J.; Wuagaman, M.; Khan, I. M.

1996-01-01

The ultimate goal of the research in smart structures and smart materials is the development of a new generation of products/devices which will perform better than products/devices built from passive materials. There are a few examples of multilayer polymer systems which function as smart structures, e.g. a synthetic muscle which is a multilayer assembly of a poly(ethylene) layer, a gold layer, and a poly(pyrrole) layer immersed in a liquid electrolyte. Oxidation and reductions of the active pyrrole layer causes the assembly to reversibly deflect and mimic biological muscles. The drawback of such a setup is slow response times and the use of a liquid electrolyte. We have developed multifunctional polymers which will eliminate the use of a liquid electrolyte, and also because the functionalities of the polymers are within a few hundred angstroms, an improved response time to changes in the external field should be possible. Such multifunctional polymers may be classified as the futuristic 'smart materials.' These materials are composed of a number of different functionalities which work in a synergistic fashion to function as a device. The device performs on the application of an external field and such multifunctional polymers may be scientifically labeled as 'field responsive polymers.' Our group has undertaken a systematic approach to develop functional and multifunctional polymers capable of functioning as field responsive polymers. Our approach utilizes multicomponent polymer systems (block copolymers and graft copolymers), the strategy involves the preparation of block or graft copolymers where the functionalities are limited to different phases in a microphase separated system. Depending on the weight (or volume) fractions of each of the components, different microstructures are possible. And, because of the intimate contact between the functional components, an increase in the synergism between the functionalities may be observed. In this presentation, three examples of multifunctional polymers developed in our labs will be reported. The first class of multifunctional polymers are the microphase separated mixed (ionic and electronic) conducting or MIEC block copolymers. The second class being developed in our labs are the biocompatible conductive materials and the conductive fluids. The final class may be considered microwave active smart polymers.

Ion Transport in Nanostructured Block Copolymer/Ionic Liquid Membranes

NASA Astrophysics Data System (ADS)

Hoarfrost, Megan Lane

Incorporating an ionic liquid into one block copolymer microphase provides a platform for combining the outstanding electrochemical properties of ionic liquids with a number of favorable attributes provided by block copolymers. In particular, block copolymers thermodynamically self-assemble into well-ordered nanostructures, which can be engineered to provide a durable mechanical scaffold and template the ionic liquid into continuous ion-conducting nanochannels. Understanding how the addition of an ionic liquid affects the thermodynamic self-assembly of block copolymers, and how the confinement of ionic liquids to block copolymer nanodomains affects their ion-conducting properties is essential for predictable structure-property control. The lyotropic phase behavior of block copolymer/ionic liquid mixtures is shown to be reminiscent of mixtures of block copolymers with selective molecular solvents. A variety of ordered microstructures corresponding to lamellae, hexagonally close-packed cylinders, body-centered cubic, and face-centered cubic oriented micelles are observed in a model system composed of mixtures of imidazolium bis(trifluoromethylsulfonyl)imide ([Im][TFSI]) and poly(styrene- b-2-vinyl pyridine) (PS-b-P2VP). In contrast to block copolymer/molecular solvent mixtures, the interfacial area occupied by each PS-b-P2VP chain decreases upon the addition of [Im][TFSI], indicating a considerable increase in the effective segregation strength of the PS-b-P2VP copolymer with ionic liquid addition. The relationship between membrane structure and ionic conductivity is illuminated through the development of scaling relationships that describe the ionic conductivity of block copolymer/ionic liquid mixtures as a function of membrane composition and temperature. It is shown that the dominant variable influencing conductivity is the overall volume fraction of ionic liquid in the mixture, which means there is incredible freedom in designing the block copolymer architecture in order to optimize the mechanical and other properties of the membrane without sacrificing conductivity. The derived scaling relationships are shown to be general for many block copolymer and ionic liquid chemistries. In certain cases, the mechanism of ion conduction in the ionic liquid is affected by block copolymer nanoconfinement. The introduction of excess neutral imidazole to [Im][TFSI] leads to enhanced proton conductivity as well as a high H+ transference number due to facilitated proton hopping between imidazole molecules. We show that there is increased proton hopping when the nonstoichiometric ionic liquid is confined to lamellar block copolymer nanodomains, which we hypothesize is due to changes in the hydrogen bond structure of the ionic liquid under confinement. This, in combination with unique ion aggregation behavior, leads to a lower activation energy for macroscopic ion transport compared to that in a corresponding homopolymer/ionic liquid mixture. Through this work, we further the understanding of the relationship between membrane composition, structure, and ion transport. The findings presented herein portend the rational design of nanostructured membranes having improved mechanical properties and conductivity.

Specificity and effector mechanisms of autoantibodies in congenital heart block.

PubMed

Wahren-Herlenius, Marie; Sonesson, Sven-Erik

2006-12-01

Complete congenital atrio-ventricular (AV) heart block develops in 2-5% of fetuses of Ro/SSA and La/SSB autoantibody-positive pregnant women. During pregnancy, the Ro/SSA and La/SSB antibodies are transported across the placenta and affect the fetus. Emerging data suggest that this happens by a two-stage process. In the first step, maternal autoantibodies bind fetal cardiomyocytes, dysregulate calcium homestasis and induce apoptosis in affected cells. This step might clinically correspond to a first-degree heart block, and be reversible. La/SSB antibodies can bind apoptotic cardiomyocytes and thus increase Ig deposition in the heart. The tissue damage could, as a second step, lead to spread of inflammation in genetically pre-disposed fetuses, progressing to fibrosis and calcification of the AV-node and subsequent complete congenital heart block. Early intrauterine treatment of an incomplete AV-block with fluorinated steroids has been shown to prevent progression of the heart block, making it clinically important to find specific markers to identify the high-risk pregnancies.

Role of the urokinase plasminogen activator receptor in mediating impaired efferocytosis of anti-SSA/Ro-bound apoptotic cardiocytes: Implications in the pathogenesis of congenital heart block.

PubMed

Briassouli, Paraskevi; Komissarova, Elena V; Clancy, Robert M; Buyon, Jill P

2010-08-06

Binding of maternal anti-Ro/La antibodies to cognate antigen expressed on apoptotic cardiocytes decreases clearance by healthy cardiocytes, which may contribute to the development of autoimmune associated congenital heart block and fatal cardiomyopathy. Given recent evidence implicating the urokinase plasminogen activator receptor (uPAR) as a "don't eat me" signal during efferocytosis, experiments addressed whether surface bound anti-Ro antibodies inhibit apoptotic cell removal via an effect on the expression/function of the urokinase-type plasminogen activator protease uPA/uPAR system. As assessed by flow cytometry and confocal microscopy, uPAR colocalizes and interacts with Ro60 on the surface of apoptotic human fetal cardiocytes. Blocking of uPAR enhances phagocytosis of apoptotic cardiocytes by healthy cardiocytes and reverses the anti-Ro60-dependent impaired clearance of apoptotic cardiocytes. Binding of anti-Ro60 antibodies to apoptotic cardiocytes results in increased uPAR expression, as well as enhanced uPA activity. The binding of anti-Ro60 did not alter other surface molecules involved in cell recognition (calreticulin, CD31, or CD47). These data suggest that increased uPAR expression and uPA activity induced by anti-Ro60 binding to the apoptotic fetal cardiocyte provide a molecular basis by which these antibodies inhibit efferocytosis and ultimately lead to scar of the fetal conduction system and working myocardium.

Inhibition of pyrimidine synthesis reverses viral virulence factor-mediated block of mRNA nuclear export

PubMed Central

Zhang, Liang; Das, Priyabrata; Schmolke, Mirco; Manicassamy, Balaji; Wang, Yaming; Deng, Xiaoyi; Cai, Ling; Tu, Benjamin P.; Forst, Christian V.; Roth, Michael G.; Levy, David E.; García-Sastre, Adolfo; de Brabander, Jef; Phillips, Margaret A.

2012-01-01

The NS1 protein of influenza virus is a major virulence factor essential for virus replication, as it redirects the host cell to promote viral protein expression. NS1 inhibits cellular messenger ribonucleic acid (mRNA) processing and export, down-regulating host gene expression and enhancing viral gene expression. We report in this paper the identification of a nontoxic quinoline carboxylic acid that reverts the inhibition of mRNA nuclear export by NS1, in the absence or presence of the virus. This quinoline carboxylic acid directly inhibited dihydroorotate dehydrogenase (DHODH), a host enzyme required for de novo pyrimidine biosynthesis, and partially reduced pyrimidine levels. This effect induced NXF1 expression, which promoted mRNA nuclear export in the presence of NS1. The release of NS1-mediated mRNA export block by DHODH inhibition also occurred in the presence of vesicular stomatitis virus M (matrix) protein, another viral inhibitor of mRNA export. This reversal of mRNA export block allowed expression of antiviral factors. Thus, pyrimidines play a necessary role in the inhibition of mRNA nuclear export by virulence factors. PMID:22312003

Decavanadate, a P2X receptor antagonist, and its use to study ligand interactions with P2X7 receptors.

PubMed

Michel, Anton D; Xing, Mengle; Thompson, Kyla M; Jones, Clare A; Humphrey, Patrick P A

2006-03-18

In this study we have studied decavanadate effects at P2X receptors. Decavanadate competitively blocked 2'- and 3'-O-(4benzoylbenzoyl) ATP (BzATP) stimulated ethidium accumulation in HEK293 cells expressing human recombinant P2X7 receptors (pK(B) 7.5). The effects of decavanadate were rapid (minutes) in both onset and offset and contrasted with the much slower kinetics of pyridoxal 5-phosphate (P5P), Coomassie brilliant blue (CBB) and 1-[N,O-bis(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenylpiperazine (KN62). Decavanadate competitively blocked the slowly reversible, or irreversible, blockade of the P2X7 receptor produced by P5P and oxidised ATP suggesting competition for a common binding site. However, the interaction between decavanadate and KN62 was non-competitive. Decavanadate also blocked P2X2 and P2X4 receptors but with slightly lower potency. These data demonstrate that decavanadate is the first reversible and competitive antagonist of the P2X7 receptor and is a useful tool for studying the mechanism of interaction of ligands with the P2X7 receptor.

Hiding Electronic Patient Record (EPR) in medical images: A high capacity and computationally efficient technique for e-healthcare applications.

PubMed

Loan, Nazir A; Parah, Shabir A; Sheikh, Javaid A; Akhoon, Jahangir A; Bhat, Ghulam M

2017-09-01

A high capacity and semi-reversible data hiding scheme based on Pixel Repetition Method (PRM) and hybrid edge detection for scalable medical images has been proposed in this paper. PRM has been used to scale up the small sized image (seed image) and hybrid edge detection ensures that no important edge information is missed. The scaled up version of seed image has been divided into 2×2 non overlapping blocks. In each block there is one seed pixel whose status decides the number of bits to be embedded in the remaining three pixels of that block. The Electronic Patient Record (EPR)/data have been embedded by using Least Significant and Intermediate Significant Bit Substitution (ISBS). The RC4 encryption has been used to add an additional security layer for embedded EPR/data. The proposed scheme has been tested for various medical and general images and compared with some state of art techniques in the field. The experimental results reveal that the proposed scheme besides being semi-reversible and computationally efficient is capable of handling high payload and as such can be used effectively for electronic healthcare applications. Copyright © 2017. Published by Elsevier Inc.

Simulation design of high reverse blocking high-K/low-K compound passivation AlGaN/GaN Schottky barrier diode with gated edge termination

NASA Astrophysics Data System (ADS)

Bai, Zhiyuan; Du, Jiangfeng; Xin, Qi; Li, Ruonan; Yu, Qi

2017-11-01

In this paper, a novel high-K/low-K compound passivation AlGaN/GaN Schottky Barrier Diode (CPG-SBD) is proposed to improve the off-state characteristics of AlGaN/GaN schottky barrier diode with gated edge termination (GET-SBD) by adding low-K blocks in to the high-K passivation layer. The reverse leakage current of CPG-SBD can be reduced to 1.6 nA/mm by reducing the thickness of high-K dielectric under GET region to 5 nm, while the forward voltage and on-state resistance keep 1 V and 3.8 Ω mm, respectively. Breakdown voltage of CPG-SBDs can be improved by inducing discontinuity of the electric field at the high-K/low-K interface. The breakdown voltage of the optimized CPG-SBD with 4 blocks of low-K can reach 1084 V with anode to cathode distance of 5 μm yielding a high FOM of 5.9 GW/cm2. From the C-V simulation results, CPG-SBDs induce no parasitic capacitance by comparison of the GET-SBDs.

Detection of alveolar rhabdomyosarcoma in pleural fluid with immunocytochemistry on cell block and determination of PAX/FKHR fusion mRNA by reverse transcription-polymerase chain reaction.

PubMed

Sawangpanich, Ruchchadol; Larbcharoensub, Noppadol; Jinawath, Artit; Pongtippan, Atcharaporn; Anurathapan, Usanarat; Hongeng, Suradej

2011-11-01

Alveolar rhabdomyosarcoma is a primitive malignant round cell neoplasm, which shows skeletal muscle differentiation. Although their histopathologic and immunohistochemical findings are well known, the cytology, immunocytochemistry and molecular study on pleural effusion have not been well documented. To apply molecular method in the diagnosis and monitoring of alveolar rhabdomyosarcoma. The case of a 14-year-old Thai male, who presented with dyspnea and left pleural effusion. Computed tomography of the chest and abdomen showed a huge heterogeneous enhancing mass at the left retroperitoneum. Pleural fluid cytology showed malignant small round blue cells. Immunocytochemical stains on cell block material showed positive reactivity to vimentin, sarcomeric actin, desmin, MyoD1, myogenin, and CD56 in round cell tumor Reverse transcription-polymerase chain reaction (RT-PCR) demonstrated PAX/FKHR fusion transcript. The patient received chemotherapeutic regimen for advanced-stage rhabdomyosarcoma. Finally, he succumbed to the disease, thirteen months after the diagnosis. Immunocytochemistry on cell block in conjunction with determination of PAX/FKHR fusion mRNA by RT-PCR is a molecular method in the diagnosis and monitoring of alveolar rhabdomyosarcoma inpleural fluid.

Nucleus accumbens dopamine D2-receptor expressing neurons control behavioral flexibility in a place discrimination task in the IntelliCage.

PubMed

Macpherson, Tom; Morita, Makiko; Wang, Yanyan; Sasaoka, Toshikuni; Sawa, Akira; Hikida, Takatoshi

2016-07-01

Considerable evidence has demonstrated a critical role for the nucleus accumbens (NAc) in the acquisition and flexibility of behavioral strategies. These processes are guided by the activity of two discrete neuron types, dopamine D1- or D2-receptor expressing medium spiny neurons (D1-/D2-MSNs). Here we used the IntelliCage, an automated group-housing experimental cage apparatus, in combination with a reversible neurotransmission blocking technique to examine the role of NAc D1- and D2-MSNs in the acquisition and reversal learning of a place discrimination task. We demonstrated that NAc D1- and D2-MSNs do not mediate the acquisition of the task, but that suppression of activity in D2-MSNs impairs reversal learning and increased perseverative errors. Additionally, global knockout of the dopamine D2L receptor isoform produced a similar behavioral phenotype to D2-MSN-blocked mice. These results suggest that D2L receptors and NAc D2-MSNs act to suppress the influence of previously correct behavioral strategies allowing transfer of behavioral control to new strategies. © 2016 Macpherson et al.; Published by Cold Spring Harbor Laboratory Press.

Integrase inhibitor reversal dynamics indicate unintegrated HIV-1 dna initiate de novo integration.

PubMed

Thierry, Sylvain; Munir, Soundasse; Thierry, Eloïse; Subra, Frédéric; Leh, Hervé; Zamborlini, Alessia; Saenz, Dyana; Levy, David N; Lesbats, Paul; Saïb, Ali; Parissi, Vincent; Poeschla, Eric; Deprez, Eric; Delelis, Olivier

2015-03-12

Genomic integration, an obligate step in the HIV-1 replication cycle, is blocked by the integrase inhibitor raltegravir. A consequence is an excess of unintegrated viral DNA genomes, which undergo intramolecular ligation and accumulate as 2-LTR circles. These circularized genomes are also reliably observed in vivo in the absence of antiviral therapy and they persist in non-dividing cells. However, they have long been considered as dead-end products that are not precursors to integration and further viral propagation. Here, we show that raltegravir action is reversible and that unintegrated viral DNA is integrated in the host cell genome after raltegravir removal leading to HIV-1 replication. Using quantitative PCR approach, we analyzed the consequences of reversing prolonged raltegravir-induced integration blocks. We observed, after RAL removal, a decrease of 2-LTR circles and a transient increase of linear DNA that is subsequently integrated in the host cell genome and fuel new cycles of viral replication. Our data highly suggest that 2-LTR circles can be used as a reserve supply of genomes for proviral integration highlighting their potential role in the overall HIV-1 replication cycle.

14 CFR 33.99 - General conduct of block tests.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Section 33.99 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.99 General conduct of block... is used for the endurance test it must be subjected to a calibration check before starting the...

14 CFR 33.99 - General conduct of block tests.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Section 33.99 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.99 General conduct of block... is used for the endurance test it must be subjected to a calibration check before starting the...

14 CFR 33.99 - General conduct of block tests.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Section 33.99 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.99 General conduct of block... is used for the endurance test it must be subjected to a calibration check before starting the...

14 CFR 33.99 - General conduct of block tests.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Section 33.99 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.99 General conduct of block... is used for the endurance test it must be subjected to a calibration check before starting the...

14 CFR 33.99 - General conduct of block tests.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Section 33.99 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.99 General conduct of block... is used for the endurance test it must be subjected to a calibration check before starting the...

Structural control on the CO2 release west of Mt. Epomeo resurgent block (Ischia, Italy)

NASA Astrophysics Data System (ADS)

de Vita, S.; Marotta, E.; Ventura, G.; Chiodini, G.

2003-04-01

Volcanism at Ischia started more than 150 ka B.P. and continued until the last eruption occurred in 1302 A.D. Ischia is dominated by the caldera forming eruption of Mt. Epomeo Green Tuff (55 ka), which was followed by block resurgence inside the caldera from 33 ka B.P. Resurgence influenced the volcanic activity determining the conditions for magma ascent mainly along the eastern edge of the resurgent block. The resurgent area has a poligonal shape resulting from reactivation of regional faults and by activation of faults related to volcanotectonism. The western sector is bordered by inward dipping, high angle strike-slip/reverse faults testifying a compressional stress regime in this area. These features are cut by late outward dipping normal faults due to gravitational stress. The activity of the volcanic system is testified by seismicity and thermal manifestations. Fumarolic activity concentrates along the faults that borders westward the Mt. Epomeo resurgent block, where the Green Tuff overlies fractured lavas. The structural data show that, outside the most active degassing zone, fractures show a NNW-SSE strike and dip toward Mt. Epomeo. These fractures delimit the northern sector of Mt. Epomeo and show strike and dip consistent with the inward dipping reverse faults. Inside the degassing area fractures show a NW-SE strike and dip outward Mt. Epomeo. These gravity-related faults cut the lavas where the hydrothermal circulation is active. The dip direction of the NW-SE striking fractures within the degassing zone is not consistent with that of the strike-slip/reverse faults (i.e. towards NE) but agrees well with that of the gravity-induced faults (dip direction towards SW). Inside the degassing zone, NW-SE striking faults with lengths not exceeding the hydrothermalized extension occur. This arrangement indicate that the syn-resurgence faults act as permeability barriers, whereas the youngest faults act as the main fluid pathway.

Formation of nanophases in epoxy thermosets containing amphiphilic block copolymers with linear and star-like topologies.

PubMed

Wang, Lei; Zhang, Chongyin; Cong, Houluo; Li, Lei; Zheng, Sixun; Li, Xiuhong; Wang, Jie

2013-07-11

In this work, we investigated the effect of topological structures of block copolymers on the formation of the nanophase in epoxy thermosets containing amphiphilic block copolymers. Two block copolymers composed of poly(ε-caprolactone) (PCL) and poly(2,2,2-trifluoroethyl acrylate) (PTFEA) blocks were synthesized to possess linear and star-shaped topologies. The star-shaped block copolymer composed a polyhedral oligomeric silsesquioxane (POSS) core and eight poly(ε-caprolactone)-block-poly(2,2,2-trifluoroethyl acrylate) (PCL-b-PTFEA) diblock copolymer arms. Both block copolymers were synthesized via the combination of ring-opening polymerization and reversible addition-fragmentation chain transfer/macromolecular design via the interchange of xanthate (RAFT/MADIX) process; they were controlled to have identical compositions of copolymerization and lengths of blocks. Upon incorporating both block copolymers into epoxy thermosets, the spherical PTFEA nanophases were formed in all the cases. However, the sizes of PTFEA nanophases from the star-like block copolymer were significantly lower than those from the linear diblock copolymer. The difference in the nanostructures gave rise to the different glass transition behavior of the nanostructured thermosets. The dependence of PTFEA nanophases on the topologies of block copolymers is interpreted in terms of the conformation of the miscible subchain (viz. PCL) at the surface of PTFEA microdomains and the restriction of POSS cages on the demixing of the thermoset-philic block (viz. PCL).

Treatment with the matricellular protein CCN3 blocks and/or reverses fibrosis development in obesity with diabetic nephropathy.

PubMed

Riser, Bruce L; Najmabadi, Feridoon; Garchow, Kendra; Barnes, Jeffrey L; Peterson, Darryl R; Sukowski, Ernest J

2014-11-01

Fibrosis is at the core of the high morbidity and mortality rates associated with the complications of diabetes and obesity, including diabetic nephropathy (DN), without any US Food and Drug Administration-approved drugs with this specific target. We recently provided the first evidence that the matricellular protein CCN3 (official symbol NOV) functions in a reciprocal manner, acting on the profibrotic family member CCN2 to inhibit fibrosis in a mesangial cell model of DN. Herein, we used the BT/BR ob/ob mouse as a best model of human obesity and DN progression to determine whether recombinant human CCN3 could be used therapeutically, and the mechanisms involved. Eight weeks of thrice-weekly i.p. injections (0.604 and 6.04 μg/kg of recombinant human CCN3) beginning in early-stage DN completely blocked and/or reversed the up-regulation of mRNA expression of kidney cortex fibrosis genes (CCN2, Col1a2, TGF-β1, and PAI-1) seen in placebo-treated diabetic mice. The treatment completely blocked glomerular fibrosis, as determined by altered mesangial expansion and deposition of laminin. Furthermore, it protected against, or reversed, podocyte loss and kidney function reduction (rise in plasma creatinine concentration); albuminuria was also greatly reduced. This study demonstrates the potential efficacy of recombinant human CCN3 treatment in DN and points to mechanisms operating at multiple levels or pathways, upstream (eg, protecting against cell injury) and downstream (eg, regulating CCN2 activity and extracellular matrix metabolism).

AMCCOM (Army Armament, Munitions and Chemical Command) Management Study of Procurement Work Directive (PWD) Processing Costs

DTIC Science & Technology

1988-05-23

Unclass) 12. PERSONAL AUTHOR(S) % Priest, Jolene J., McIllece, Raymond P. I 13a. TYPE OF REPORT 13b. TIME COVERED 14. DATE OF REPORT (Year, Month...and identify by block number) FIELD GROUP SUB-GROUP Procurement (u), Procurement Work Directive (PWD) (u), Administrative Lead Time (ALT) (u...Procurement Administra-( A A o e e e time Lead Time (PALf) (u) "p 19. ABSTRACT (Continue on reverse if necessary and identify by block number) The practice of

Butadiene-Isoprene Block Copolymers and Their Hydrogenated Derivatives.

DTIC Science & Technology

1981-04-01

polyethylene, LDPE. The crystallinity, density and AHf for all of the block copolymers were found to be linearly de - pendent on HB content indicating...etc. It is known for example, that carbanions can exist in "tight", "loose", or even "free" structures as a function of counterion and solvent. (5,6...is then observed for the styrene segment. Thus in these systems , there is an apparent "reversal of reactivity" of styrene and the diene, since for the

Visual System Neural Responses to Laser Exposure from Local Q-Switched Pulses and Extended Source CW Speckle Patterns.

DTIC Science & Technology

1985-09-30

layers of the retina as seen in retinitis pigmentosa (Wolbarsht & Landers, 1980; Stefansson et al, 1981 a). Those are all long-term effects with a delay...block numoer) FIELD GROUP SUB-GROUP retinal damage center-surround 20 05 laser injury cat retina 20 06 visual perception N02 anesthesia 19. ABSTRACT...Continue on reverse if necessary and identify by block number) The reports of retinal damage from exposure to short pulse laser energy without any

Photoionization of Atoms and Ions: Application of Time-Dependent Response Method within the Density Functional Theory.

DTIC Science & Technology

1987-10-13

AD-A±95 686 PHOTOIONIZATION OF ATOMS AND IONS: APPLICATION OF III TIME-DEPENDENT RESPONSE..(U) NAVAL RESEARCH LAB WASHINGTON DC U GUPTA ET AL. 13 OCT...on revere if ncemy and idmntify by block number) FIELD GROUP SUBGROUP Photoionization Density functional Atoms Time dependent 1 S. (Continue on...reverse if necenary and identify by block numnbw) The photoionization cross-section of several atoms (AT, Xe, Rn, Cs) and ions (Ne-like Ar, H-like and Li

Sketched oxide single-electron transistor

NASA Astrophysics Data System (ADS)

Cheng, Guanglei; Siles, Pablo F.; Bi, Feng; Cen, Cheng; Bogorin, Daniela F.; Bark, Chung Wung; Folkman, Chad M.; Park, Jae-Wan; Eom, Chang-Beom; Medeiros-Ribeiro, Gilberto; Levy, Jeremy

2011-06-01

Devices that confine and process single electrons represent an important scaling limit of electronics. Such devices have been realized in a variety of materials and exhibit remarkable electronic, optical and spintronic properties. Here, we use an atomic force microscope tip to reversibly `sketch' single-electron transistors by controlling a metal-insulator transition at the interface of two oxides. In these devices, single electrons tunnel resonantly between source and drain electrodes through a conducting oxide island with a diameter of ~1.5 nm. We demonstrate control over the number of electrons on the island using bottom- and side-gate electrodes, and observe hysteresis in electron occupation that is attributed to ferroelectricity within the oxide heterostructure. These single-electron devices may find use as ultradense non-volatile memories, nanoscale hybrid piezoelectric and charge sensors, as well as building blocks in quantum information processing and simulation platforms.

The role of tortuosity on ion conduction in block copolymer electrolyte thin films

NASA Astrophysics Data System (ADS)

Kambe, Yu; Arges, Christopher G.; Nealey, Paul F.

This talk discusses the role of grain tortuosity on ion conductivity in block copolymer electrolyte (BCE) thin films. In particular, we studied lamellae forming BCEs with both domains oriented perpendicular to the substrate surface and connected directly from one electrode to another - i.e., tortuosity of one. The BCE is composed of ion-conducting, poly(2-vinyl n-methylpyridinium) blocks and non-ionic polystyrene blocks. Prior to creating the BCE, the pristine block copolymer, poly(styrene- b-2-vinyl pyridine), was directly self-assembled (DSA) on topographical or chemical patterns via graphoepitaxy and chemoepitaxy. A chemical vapor infiltration reaction modified the P2VP block into positively charged, fixed quaternary ammonium groups paired with mobile counteranions. The graphoepitaxy process utilized topographical interdigitated gold nanoelectrodes (100s of nanometers spacing between electrodes) created via e-beam lithography. Alternatively, chemical patterns had gold electrodes incorporated into them with 10s to 100s of microns spacing using conventional optical lithography. The interdigitated gold electrodes enabled in-plane ion conductivity measurements of the DSA BCEs to study the role of grain tortuosity on ion conductivity. U.S. Department of Energy Office of Science: Contract No. DE-AC02-06CH11357.

Fire resistant nuclear fuel cask

DOEpatents

Heckman, Richard C.; Moss, Marvin

1979-01-01

The disclosure is directed to a fire resistant nuclear fuel cask employing reversibly thermally expansible bands between adjacent cooling fins such that normal outward flow of heat is not interfered with, but abnormal inward flow of heat is impeded or blocked.

Strain-controlled thermal conductivity in ferroic twinned films

PubMed Central

Li, Suzhi; Ding, Xiangdong; Ren, Jie; Moya, Xavier; Li, Ju; Sun, Jun; Salje, Ekhard K. H.

2014-01-01

Large reversible changes of thermal conductivity are induced by mechanical stress, and the corresponding device is a key element for phononics applications. We show that the thermal conductivity κ of ferroic twinned thin films can be reversibly controlled by strain. Nonequilibrium molecular dynamics simulations reveal that thermal conductivity decreases linearly with the number of twin boundaries perpendicular to the direction of heat flow. Our demonstration of large and reversible changes in thermal conductivity driven by strain may inspire the design of controllable thermal switches for thermal logic gates and all-solid-state cooling devices. PMID:25224749

Toll-like receptor 7 agonists are potent and rapid bronchodilators in guinea pigs

PubMed Central

Kaufman, Elad H.; Fryer, Allison D.; Jacoby, David B.

2011-01-01

Background Respiratory tract viral infections result in asthma exacerbations. Toll-like receptor (TLR) 7 is a receptor for viral single-stranded RNA and is expressed at high levels in the lungs. Objective Because TLR7 polymorphisms are associated with asthma, we examined the effects of TLR7 agonists in guinea pig airways. Methods We induced bronchoconstriction in guinea pigs in vivo by means of electrical stimulation of the vagus nerve or intravenous administration of acetylcholine and measured the effect of a TLR7 agonist administered intravenously. We induced contraction of airway smooth muscle in segments of isolated guinea pig tracheas in vitro and measured the effect of TLR7 agonists, antagonists, and pharmacologic inhibitors of associated signaling pathways administered directly to the bath. Results TLR7 agonists acutely inhibited bronchoconstriction in vivo and relaxed contraction of airway smooth muscle in vitro within minutes of administration. Airway relaxation induced by the TLR7 agonist R837 (imiquimod) was partially blocked with a TLR7 antagonist and was also blocked by inhibitors of large-conductance, calcium-activated potassium channels; prostaglandin synthesis; and nitric oxide generation. Another TLR7 agonist, 21-mer single-stranded phosphorothioated polyuridylic acid (PolyUs), mediated relaxation that was completely blocked by a TLR7 antagonist. Conclusions These data demonstrate a novel protective mechanism to limit bronchoconstriction and maintain airflow during respiratory tract viral infections. The fast time frame is inconsistent with canonical TLR7 signaling. R837 mediates bronchodilation by means of TLR7-dependent and TLR7-independent mechanisms, whereas PolyUs does so through only the TLR7-dependent mechanism. TLR7-independent mechanisms involve prostaglandins and large-conductance, calcium-activated potassium channels, whereas TLR7-dependent mechanisms involve nitric oxide. TLR7 is an attractive therapeutic target for its ability to reverse bronchoconstriction within minutes. PMID:21167577

Depolarization- and transmitter-induced changes in intracellular Ca2+ of rat cerebellar granule cells in explant cultures.

PubMed

Connor, J A; Tseng, H Y; Hockberger, P E

1987-05-01

Digital imaging of the Ca indicator fura-2 has been used to study the responses of developing granule cells in culture to depolarization and transmitter action. Unstimulated cells bathed in Krebs saline exhibited cytoplasmic Ca ion concentrations, [Ca2+], that were generally in the 30-60 nM range. Exposure of cells to high-potassium (25 mM) saline depolarized the membrane potential and produced an immediate rise in [Ca2+] that recovered within 2-3 min in normal saline. The response grew progressively larger over the first 20 d in culture. Transient increases in [Ca2+] to levels greater than 1 microM were observed after 12-14 d in vitro, at which time the cells displayed intense electrical activity when exposed to high K. At this stage, the increases were attenuated by blocking action potential activity with TTX. In TTX-treated or immature cells, in which the transient phase of the Ca change was relatively small, a second exposure to high K typically produced a much larger Ca response that the initial exposure. The duration of this facilitation of the response persisted for periods longer than 5 min. Application of the neurotransmitter GABA induced a transient increase in membrane conductance, with a reversal potential near resting potential (approx. -60 mV), and caused an intracellular Ca2+ increase that outlasted the exposure to GABA by several minutes. Glutamate, or kainate, induced an increase in membrane conductance but with a reversal potential more positive than spike threshold. These agents also elevated intracellular Ca2+, but unlike the case with GABA, this Ca response reversed rapidly upon removal of the transmitter. The facilitatory effect of repeated exposures to high-K saline, as well as the persistent Ca elevation following a brief GABA application, suggests that granule cells possess the capability of displaying activity-dependent changes in Ca levels in culture.

Effects of strychnine on the sodium conductance of the frog node of Ranvier

PubMed Central

1977-01-01

Strychnine blocks sodium conductance in the frog node of Ranvier. This block was studied by reducing and slowing sodium inactivation with scorpion venom. The block is voltage and time dependent. The more positive the axoplasm the greater the block and the faster the approach to equilibrium. Some evidence is presented suggesting that only open channels can be blocked. The block is reduced by raising external sodium or lithium but not impermeant cations. A quaternary derivative of strychnine was synthesized and found to have the same action only when applied intracellularly. We conclude that strychnine blocks sodium channels by a mechanism analogous to that by which it blocks potassium channels. The potassium channel block had previously been found to be identical to that by tetraethylammonium ion derivatives. In addition, strychnine resembles procaine and its derivatives in both its structure and the mechanism of sodium channel block. PMID:302321

Amphiphilic block copolymer membrane for vanadium redox flow battery

NASA Astrophysics Data System (ADS)

Wang, Fei; Sylvia, James M.; Jacob, Monsy M.; Peramunage, Dharmasena

2013-11-01

An amphiphilic block copolymer comprised of hydrophobic polyaryletherketone (PAEK) and hydrophilic sulfonated polyaryletherketone (SPAEK) blocks has been synthesized and characterized. A membrane prepared from the block copolymer is used as the separator in a single cell vanadium redox flow battery (VRB). The proton conductivity, mechanical property, VO2+ permeability and single VRB cell performance of this block copolymer membrane are investigated and compared to Nafion™ 117. The block copolymer membrane showed significantly improved vanadium ion selectivity, higher mechanical strength and lower conductivity than Nafion™ 117. The VRB containing the block copolymer membrane exhibits higher coulombic efficiency and similar energy efficiency compared to a VRB using Nafion™ 117. The better vanadium ion selectivity of the block copolymer membrane has led to a much smaller capacity loss during 50 charge-discharge cycles for the VRB.

Improvement of reverse blocking performance in vertical power MOSFETs with Schottky-drain-connected semisuperjunctions

NASA Astrophysics Data System (ADS)

Mao, Wei; Wang, Hai-Yong; Wang, Xiao-Fei; Du, Ming; Zhang, Jin-Feng; Zheng, Xue-Feng; Wang, Chong; Ma, Xiao-Hua; Zhang, Jin-Cheng; Hao, Yue

2017-04-01

Not Available Project supported by the National Natural Science Foundation of China (Grant Nos. 61574112, 61334002, 61306017, 61474091, and 61574110) and the Natural Science Basic Research Plan in Shaanxi Province of China (Grant No. 605119425012).

Production of lunar fragmental material by meteoroid impact.

NASA Technical Reports Server (NTRS)

Marcus, A. H.

1973-01-01

The rate of production of new fragmental lunar surface material is derived theoretically on the hypothesis that such material is excavated from a bedrock layer by meteoroid impacts. An overlaying regolith effectively shields the bedrock layer from small impacts, reducing the production rate of centimeter-sized and smaller blocks by a large factor. Logarithmic production rate curves for centimeter to motor-sized blocks are nonlinear for any regolith from centimeters to tens of meters in thickness, with small blocks relatively much less frequent for thicker (older) regoliths, suggesting the possibility of a statistical reverse bedding. Modest variations in the exponents of scaling laws for crater depth-diameter ratio and maximum block-diameter to crater diameter ratio are shown to have significant effects on the production rates. The production rate increases slowly with increasing size of the largest crater affecting the region.

Chloride channel blockers activate an endogenous cationic current in oocytes of Bufo arenarum.

PubMed

Cavarra, M S; del Mónaco, S M; Kotsias, B A

2004-07-01

A two-electrode, voltage-clamp technique was used to measure the effect of the Cl(-) channel blockers, 9-anthracene carboxylic acid and niflumic acid, upon the ionic currents of oocytes of the South American toad Bufo arenarum. The main results were: (1) both blockers produced a reversible increase of the outward currents on a dose-dependent manner; (2) the activated outward current was voltage dependent; (3) the 9-anthracene carboxylic acid-sensitive current was blocked with barium; and (4) the effect of 9-anthracene carboxylic acid was more pronounced in a zero-K(+) solution than in standard (2 mmol l(-1)) or high (20 mmol l(-1)) K(+) solutions, indicating that a K(+) conductance is activated. The effect of the Cl(-) channel blockers could be due to a direct interaction with endogenous cationic channels. Another possible explanation is that Cl(-) that enter the cell during depolarizing steps in control solution inhibit this cationic conductance; thus, the blockade of Cl(-) channels by 9-anthracene carboxylic acid and niflumic acid would remove this inhibition, allowing the cationic current to flow freely.

Treatment of cartilage with beta-aminopropionitrile accelerates subsequent collagen maturation and modulates integrative repair.

PubMed

McGowan, Kevin B; Sah, Robert L

2005-05-01

Integrative repair of cartilage was previously found to depend on collagen synthesis and maturation. beta-aminopropionitrile (BAPN) treatment, which irreversibly blocks lysyl oxidase, inhibited the formation of collagen crosslinks, prevented development of adhesive strength, and caused a buildup of GuHCl-extractable collagen crosslink precursors. This buildup of crosslink precursor in the tissue may be useful for enhancing integrative repair. We tested in vitro the hypothesis that pre-treatment of cartilage with BAPN, followed by washout before implantation, could be a useful therapeutic strategy to accelerate subsequent collagen maturation. In individual cartilage disks, collagen processing was reversibly blocked by BAPN treatment (0.1 mM) as indicated by a BAPN-induced increase in the total and proportion of incorporated radiolabel that was extractable by 4M guanidine-HCl, followed by a decrease, within 3-4 days of BAPN washout, in the proportion of extractable radiolabel to control levels. With a similar pattern, integration between pairs of apposed cartilage blocks was reversibly blocked by BAPN treatment, and followed by an enhancement of integration after BAPN washout. The low and high levels of integration were associated with enrichment in [(3)H]proline in a form that was susceptible and resistant, respectively, to extraction. With increasing duration up to 7 days after BAPN pre-treatment, the levels of [(3)H]proline extraction decreased, and the development of adhesive strength increased. Thus, BAPN can be used to modulate integrative cartilage repair.

Oblique Northeastward Lateral Extrusion of a Crustal Block in North-central Taiwan: a Mechanism for Syn-tectonic Extension

NASA Astrophysics Data System (ADS)

Gourley, J. R.; Byrne, T.

2005-12-01

An integrated data set of earthquake locations (Taiwan's Central Weather Bureau), focal mechanisms from the Broadband Array of Taiwan Seismicity (BATS), GPS velocities and geologic data are combined to constrain the geometry and kinematics of a crustal block within the metamorphic basement of Taiwan's northeastern Central Range. The active block is bounded by two parallel seismic zones that accommodate uplift and northeastward oblique lateral extrusion. The western shear zone is a region that dips vertically to steeply west and projects generally to the western boundary between the Slate Belt and pre-Tertiary metamorphic basement. BATS focal mechanisms consistently show east-side-up, left-lateral normal displacements. Late-stage geologic structures published previously show left-lateral faulting followed by east-west extension. The eastern shear zone dips vertically to steeply west and projects to the eastern boundary of the metamorphic basement, which correlates with the eastern mountain front in this area. BATS focal mechanisms show west-side-up reverse displacements. The kinematics of these two zones define a crustal scale block that is interpreted to be moving up and northeast towards the Okinawa Trough. The extrusion of this crustal block may be driven in part by the topographic difference between the Central Range and the Okinawa Trough, as well as by the active collision between the Philippine Sea Plate and the Eurasian basement high. This proposed northeastern lateral extrusion mirrors the active lateral extrusion in southwestern Taiwan which is observed on the southern side of the Eurasian basement high collision. The involvement of the basement high in the collision and adjacent regions appears to be an important factor in understanding local structural variations in the arc-continent collision and should be considered in both forward and reverse modeling of Taiwan deformation.

Cytomegalovirus Virions Shed in Urine Have a Reversible Block to Epithelial Cell Entry and Are Highly Resistant to Antibody Neutralization

PubMed Central

Cui, Xiaohong; Adler, Stuart P.; Schleiss, Mark R.; Demmler Harrison, Gail J.

2017-01-01

ABSTRACT Cytomegalovirus (CMV) causes sensorineural hearing loss and developmental disabilities in newborns when infections are acquired in utero. Pregnant women may acquire CMV from oral exposure to CMV in urine or saliva from young children. Neutralizing antibodies in maternal saliva have the potential to prevent maternal infection and, in turn, fetal infection. As CMV uses different viral glycoprotein complexes to enter different cell types, the first cells to be infected in the oral cavity could determine the type of antibodies needed to disrupt oral transmission. Antibodies targeting the pentameric complex (PC) should block CMV entry into epithelial cells but not into fibroblasts or Langerhans cells (which do not require the PC for entry), while antibodies targeting glycoprotein complexes gB or gH/gL would be needed to block entry into fibroblasts, Langerhans cells, or other cell types. To assess the potential for antibodies to disrupt oral acquisition, CMV from culture-positive urine samples (uCMV) was used to study cell tropisms and sensitivity to antibody neutralization. uCMV entered epithelial cells poorly compared with the entry into fibroblasts. CMV-hyperimmune globulin or monoclonal antibodies targeting gB, gH/gL, or the PC were incapable of blocking the entry of uCMV into either fibroblasts or epithelial cells. Both phenotypes were lost after one passage in cultured fibroblasts, suggestive of a nongenetic mechanism. These results suggest that uCMV virions have a reversible block to epithelial cell entry. Antibodies may be ineffective in preventing maternal oral CMV acquisition but may limit viral spread in blood or tissues, thereby reducing or preventing fetal infection and disease. PMID:28404573

Efficacy of Tricaine Methanesulfonate (MS-222) as an Anesthetic Agent for Blocking Sensory-Motor Responses in Xenopus laevis Tadpoles

PubMed Central

Ramlochansingh, Carlana; Branoner, Francisco; Chagnaud, Boris P.; Straka, Hans

2014-01-01

Anesthetics are drugs that reversibly relieve pain, decrease body movements and suppress neuronal activity. Most drugs only cover one of these effects; for instance, analgesics relieve pain but fail to block primary fiber responses to noxious stimuli. Alternately, paralytic drugs block synaptic transmission at neuromuscular junctions, thereby effectively paralyzing skeletal muscles. Thus, both analgesics and paralytics each accomplish one effect, but fail to singularly account for all three. Tricaine methanesulfonate (MS-222) is structurally similar to benzocaine, a typical anesthetic for anamniote vertebrates, but contains a sulfate moiety rendering this drug more hydrophilic. MS-222 is used as anesthetic in poikilothermic animals such as fish and amphibians. However, it is often argued that MS-222 is only a hypnotic drug and its ability to block neural activity has been questioned. This prompted us to evaluate the potency and dynamics of MS-222-induced effects on neuronal firing of sensory and motor nerves alongside a defined motor behavior in semi-intact in vitro preparations of Xenopus laevis tadpoles. Electrophysiological recordings of extraocular motor discharge and both spontaneous and evoked mechanosensory nerve activity were measured before, during and after administration of MS-222, then compared to benzocaine and a known paralytic, pancuronium. Both MS-222 and benzocaine, but not pancuronium caused a dose-dependent, reversible blockade of extraocular motor and sensory nerve activity. These results indicate that MS-222 as benzocaine blocks the activity of both sensory and motor nerves compatible with the mechanistic action of effective anesthetics, indicating that both caine-derivates are effective as single-drug anesthetics for surgical interventions in anamniotes. PMID:24984086

Mesoporous block-copolymer nanospheres prepared by selective swelling.

PubMed

Mei, Shilin; Jin, Zhaoxia

2013-01-28

Block-copolymer (BCP) nanospheres with hierarchical inner structure are of great interest and importance due to their possible applications in nanotechnology and biomedical engineering. Mesoporous BCP nanospheres with multilayered inner channels are considered as potential drug-delivery systems and templates for multifunctional nanomaterials. Selective swelling is a facile pore-making strategy for BCP materials. Herein, the selective swelling-induced reconstruction of BCP nanospheres is reported. Two poly(styrene-block-2-vinylpyridine) (PS-b-P2VP) samples with different compositions (PS(23600)-b-P2VP(10400) and PS(27700)-b-P2VP(4300)) are used as model systems. The swelling reconstruction of PS-b-P2VP in ethanol, 1-pyrenebutyric acid (PBA)/ethanol, or HCl/ethanol (pH = 2.61) is characterized by scanning electron microscopy and transmission electron microscopy. It is observed that the length of the swellable block in BCP is a critical factor in determining the behavior and nanostructures of mesoporous BCP nanospheres in selective swelling. Moreover, it is demonstrated that the addition of PBA modifies the swelling structure of PS(23600)-b-P2VP(10400) through the interaction between PBA and P2VP blocks, which results in BCP nanospheres with patterned pores of controllable size. The patterned pores can be reversibly closed by annealing the mesoporous BCP nanospheres in different selective solvents. The controllable and reversible open/closed reconstruction of BCP nanospheres can be used to enclose functional nanoparticles or drugs inside the nanospheres. These mesoporous BCP nanospheres are further decorated with gold nanoparticles by UV photoreduction. The enlarged decoration area in mesoporous BCP nanospheres will enhance their activity and sensitivity as a catalyst and electrochemical sensor. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Miocene block uplift and basin formation in the Patagonian foreland: The Gastre Basin, Argentina

NASA Astrophysics Data System (ADS)

Bilmes, A.; D'Elia, L.; Franzese, J. R.; Veiga, G. D.; Hernández, M.

2013-08-01

The intraplate fault-block mountains and intermontane deposits of the Gastre Basin, which are recorded more than 550 km east of the Andean trench in central Patagonia, Argentina, are analyzed. The Gastre Basin is one of the largest Patagonian intermontane basins, limited by uplifted blocks strongly oblique to the Andean chain. It was originated by reverse faulting and inversion of pre-existing normal faults associated with a Mesozoic rift basin and defined by older crustal heterogeneities. The deformational event occurred during the middle Miocene, related to a short contractional episode (16.1-14.86 Ma), probably in response to an eastward migration of the Andean fold and thrust belt. During Pliocene to Quaternary times, neither younger fault-block uplifts nor reconfigurations of the basin occurred. Similarities between the study area and other parts of the Patagonian foreland - such as the presence of Miocene reverse or inversion tectonics, as well as the accommodation of the Miocene sedimentary successions - suggest that the Gastre Basin is part of a major late early to middle Miocene broken foreland system (i.e. the Patagonian broken foreland) that exhumed discrete fault-block mountains and generated contemporary basins along more than 950 km parallel to the Andean trench (i.e. between 40°00' and 48°00' south latitude). Based on recent studies on the southern Andean Margin, this continental-scale contractional episode may be the result of a flat-slab subduction segment. Nevertheless, such a hypothesis is very difficult to support when analyzing such a large flat subduction segment along the entire Patagonian trench. This suggests the need to consider alternative flat-slab trigger mechanisms or other factors in the generation of broken foreland systems.

Nucleoside reverse transcriptase inhibitors possess intrinsic anti-inflammatory activity

PubMed Central

Fowler, Benjamin J.; Gelfand, Bradley D.; Kim, Younghee; Kerur, Nagaraj; Tarallo, Valeria; Hirano, Yoshio; Amarnath, Shoba; Fowler, Daniel H.; Radwan, Marta; Young, Mark T.; Pittman, Keir; Kubes, Paul; Agarwal, Hitesh K.; Parang, Keykavous A.; Hinton, David R.; Bastos-Carvalho, Ana; Li, Shengjian; Yasuma, Tetsuhiro; Mizutani, Takeshi; Yasuma, Reo; Wright, Charles; Ambati, Jayakrishna

2014-01-01

Nucleoside reverse transcriptase inhibitors (NRTIs) are mainstay therapeutics for HIV that block retrovirus replication. Alu (an endogenous retroelement that also requires reverse transcriptase for its life cycle)-derived RNAs activate P2X7 and the NLRP3 inflammasome to cause cell death of the retinal pigment epithelium (RPE) in geographic atrophy, a type of age-related macular degeneration. We found that NRTIs inhibit P2X7-mediated NLRP3 inflammasome activation independent of reverse transcriptase inhibition. Multiple approved and clinically relevant NRTIs prevented caspase-1 activation, the effector of the NLRP3 inflammasome, induced by Alu RNA. NRTIs were efficacious in mouse models of geographic atrophy, choroidal neovascularization, graft-versus-host disease (GVHD), and sterile liver inflammation. Our findings suggest that NRTIs are ripe for drug repurposing in P2X7-driven diseases. PMID:25414314

Ephrin reverse signaling mediates palatal fusion and epithelial-to-mesenchymal transition independently of Tgfß3.

PubMed

Serrano, Maria J; Liu, Jingpeng; Svoboda, Kathy K H; Nawshad, Ali; Benson, M Douglas

2015-12-01

The mammalian secondary palate forms from shelves of epithelia-covered mesenchyme that meet at midline and fuse. The midline epithelial seam (MES) is thought to degrade by apoptosis, epithelial-to-mesenchymal transition (EMT), or both. Failure to degrade the MES blocks fusion and causes cleft palate. It was previously thought that transforming growth factor ß3 (Tgfß3) is required to initiate fusion. Members of the Eph tyrosine kinase receptor family and their membrane-bound ephrin ligands are expressed on the MES. We demonstrated that treatment of mouse palates with recombinant EphB2/Fc to activate ephrin reverse signaling (where the ephrin acts as a receptor and transduces signals from its cytodomain) was sufficient to cause mouse palatal fusion when Tgfß3 signaling was blocked by an antibody against Tgfß3 or by an inhibitor of the TgfßrI serine/threonine receptor kinase. Cultured palatal epithelial cells traded their expression of epithelial cell markers for that of mesenchymal cells and became motile after treatment with EphB2/Fc. They concurrently increased their expression of the EMT-associated transcription factors Snail, Sip1, and Twist1. EphB2/Fc did not cause apoptosis in these cells. These data reveal that ephrin reverse signaling directs palatal fusion in mammals through a mechanism that involves EMT but not apoptosis and activates a gene expression program not previously associated with ephrin reverse signaling. © 2015 Wiley Periodicals, Inc.

Pharmacological modulation of neuropathic pain-related depression of behavior: Effects of morphine, ketoprofen, bupropion and Δ9-tetrahydrocannabinol on formalin-induced depression of intracranial self-stimulation (ICSS) in rats

PubMed Central

Leitl, Michael D.; Negus, Stevens

2015-01-01

Neuropathic pain is often associated with behavioral depression. Intraplantar formalin produces sustained, neuropathy-associated depression of intracranial self-stimulation (ICSS) in rats. This study evaluated pharmacological modulation of formalin-induced ICSS depression. Rats with intracranial electrodes targeting the medial forebrain bundle responded for electrical brain stimulation in an ICSS procedure. Bilateral intraplantar formalin administration depressed ICSS for 14 days. Morphine (0.32–3.2 mg/kg), ketoprofen (0.1–10 mg/kg), bupropion (3.2–32 mg/kg), and Δ9-tetrahydrocannabinol (THC; 0.32–3.2 mg/kg) were evaluated for their effectiveness to reverse formalin-induced depression of ICSS. Drug effects on formalin-induced mechanical allodynia were evaluated for comparison. Morphine and bupropion reversed both formalin-induced ICSS depression and mechanical allodynia, and effects on ICSS were sustained during repeated treatment. Ketoprofen failed to reverse either formalin effect. THC blocked mechanical allodynia, but decreased ICSS in control rats and exacerbated formalin-induced depression of ICSS. The failure of ketoprofen to alter formalin effects suggests that formalin effects result from neuropathy rather than inflammation. The effectiveness of morphine and bupropion to reverse formalin effects agrees with other evidence that these drugs block pain-depressed behavior in rats and relieve neuropathic pain in humans. The effects of THC suggest general behavioral suppression and do not support the use of THC to treat neuropathic pain. PMID:26588213

Selective Erasure of Distinct Forms of Long-Term Synaptic Plasticity Underlying Different Forms of Memory in the Same Postsynaptic Neuron.

PubMed

Hu, Jiangyuan; Ferguson, Larissa; Adler, Kerry; Farah, Carole A; Hastings, Margaret H; Sossin, Wayne S; Schacher, Samuel

2017-07-10

Generalization of fear responses to non-threatening stimuli is a feature of anxiety disorders. It has been challenging to target maladaptive generalized memories without affecting adaptive memories. Synapse-specific long-term plasticity underlying memory involves the targeting of plasticity-related proteins (PRPs) to activated synapses. If distinct tags and PRPs are used for different forms of plasticity, one could selectively remove distinct forms of memory. Using a stimulation paradigm in which associative long-term facilitation (LTF) occurs at one input and non-associative LTF at another input to the same postsynaptic neuron in an Aplysia sensorimotor preparation, we found that each form of LTF is reversed by inhibiting distinct isoforms of protein kinase M (PKM), putative PRPs, in the postsynaptic neuron. A dominant-negative (dn) atypical PKM selectively reversed associative LTF, while a dn classical PKM selectively reversed non-associative LTF. Although both PKMs are formed from calpain-mediated cleavage of protein kinase C (PKC) isoforms, each form of LTF is sensitive to a distinct dn calpain expressed in the postsynaptic neuron. Associative LTF is blocked by dn classical calpain, whereas non-associative LTF is blocked by dn small optic lobe (SOL) calpain. Interfering with a putative synaptic tag, the adaptor protein KIBRA, which protects the atypical PKM from degradation, selectively erases associative LTF. Thus, the activity of distinct PRPs and tags in a postsynaptic neuron contribute to the maintenance of different forms of synaptic plasticity at separate inputs, allowing for selective reversal of synaptic plasticity and providing a cellular basis for developing therapeutic strategies for selectively reversing maladaptive memories. Copyright © 2017 Elsevier Ltd. All rights reserved.

Novel Self-Assembling Amino Acid-Derived Block Copolymer with Changeable Polymer Backbone Structure.

PubMed

Koga, Tomoyuki; Aso, Eri; Higashi, Nobuyuki

2016-11-29

Block copolymers have attracted much attention as potentially interesting building blocks for the development of novel nanostructured materials in recent years. Herein, we report a new type of self-assembling block copolymer with changeable polymer backbone structure, poly(Fmoc-Ser) ester -b-PSt, which was synthesized by combining the polycondensation of 9-fluorenylmethoxycarbonyl-serine (Fmoc-Ser) with the reversible addition-fragmentation chain transfer (RAFT) polymerization of styrene (St). This block copolymer showed the direct conversion of the backbone structure from polyester to polypeptide through a multi O,N-acyl migration triggered by base-induced deprotection of Fmoc groups in organic solvent. Such polymer-to-polymer conversion was found to occur quantitatively without decrease in degree of polymerization and to cause a drastic change in self-assembling property of the block copolymer. On the basis of several morphological analyses using FTIR spectroscopy, atomic force, and transmission and scanning electron microscopies, the resulting peptide block copolymer was found to self-assemble into a vesicle-like hollow nanosphere with relatively uniform diameter of ca. 300 nm in toluene. In this case, the peptide block generated from polyester formed β-sheet structure, indicating the self-assembly via peptide-guided route. We believe the findings presented in this study offer a new concept for the development of self-assembling block copolymer system.

Study on the crystallographic orientation relationship and formation mechanism of reversed austenite in economical Cr12 super martensitic stainless steel

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

Ye, Dong; Li, Shaohong; Li, Jun

Effect of carbides and crystallographic orientation relationship on the formation mechanism of reversed austenite of economical Cr12 super martensitic stainless steel (SMSS) has been investigated mainly by transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD). The results indicate that the M{sub 23}C{sub 6} precipitation and the formation of the reversed austenite have the interaction effect during tempering process in SMSS. The reversed austenite forms intensively at the sub-block boundary and the lath boundary within a misorientation range of 0–60°. M{sub 23}C{sub 6} has the same crystallographic orientation relationship with reversed austenite. There are two different kinds of formation modesmore » for reversed austenite. One is a nondiffusional shear reversion; the other is a diffusion transformation. Both are strictly limited by crystallographic orientation relationship. The austenite variants are limited to two kinds within one packet and five kinds within one prior austenite grain. - Highlights: • Reversed austenite forms at martensite boundaries with misorientation of 0–60° • M{sub 23}C{sub 6} precipitation and reversed austenite formation have the interaction effect. • Two austenite variants with different orientations can be formed inside a packet. • Two reversed austenite formation modes: shear reversion; diffusion transformation.« less

Second-Degree Interatrial Block in Hemodialysis Patients

PubMed Central

Enriquez, Andres; D'Amato, Anna; de Luna, Antoni Bayes; Baranchuk, Adrian

2015-01-01

Interatrial conduction delays manifest as a prolonged P-wave duration on surface ECG and the term interatrial block (IAB) has been coined. They are usually fixed, but cases of intermittent IAB have been described, suggesting functional conduction block at the Bachmann bundle region. We report 2 cases of patients on chronic hemodialysis therapy presenting with intermittent IAB. PMID:25755895

Pacing-induced chronic atrial fibrillation impairs sinus node function in dogs. Electrophysiological remodeling.

PubMed

Elvan, A; Wylie, K; Zipes, D P

1996-12-01

We assessed the effects of pacing-induced chronic atrial fibrillation (AF) on sinus node function, intra-atrial conduction, and atrial refractoriness. In 15 mongrel dogs (20 to 30 kg), AV nodal block was produced by radiofrequency catheter ablation, and a ventricular-inhibited (VVI) pacemaker (Minix 8330, Medtronic) was implanted and programmed to pace at 80 pulses per minute. In 11 of these dogs, right atrial endocardial pacing leads were connected to a pulse generator (Itrel 7432, Medtronic) and set at a rate of 20 Hz to induce AF. Corrected sinus node recovery time, P-wave duration, 24-hour Holter ECG to assess AF duration, maximal heart rate in response to isoproterenol (10 micrograms/min), intrinsic heart rate after administration of atropine (0.04 mg/kg) and propranolol (0.1 mg/kg), and atrial effective refractory periods (ERPs) were obtained at baseline (EPS-1) and after 2 to 6 weeks (EPS-2) of VVI pacing alone (n = 4) or VVI pacing and rapid atrial pacing (n = 11). At EPS-2, corrected sinus node recovery time and P-wave duration were prolonged, maximal heart rate and intrinsic heart rate were decreased, atrial ERPs were shortened, and the duration of AF was increased significantly compared with EPS-1. These changes partially reversed toward baseline 1 week after conversion to sinus rhythm. Sinus node function and AF inducibility observed in the control dogs that underwent ventricular pacing alone (n = 4) did not change. Pacing-induced chronic AF induces sinus node dysfunction, prolongs intra-atrial conduction time, shortens atrial refractoriness, and perpetuates AF, changes that reverse gradually after termination of AF.

F14A System Safety Program Plan

DTIC Science & Technology

1981-09-03

by block number) Electromagnetic Pulse (EMP) Safety Plans Test Program EMP Testing F14 Aircraft Plans 20 ABSTRACT (Continue on reverse side if...compromising completion of the required experimental tasks. This document addresses the safety aspect of performing an Electromagnetic Pulse (EMP) test

Thrust reverser design studies for an over-the-wing STOL transport

NASA Technical Reports Server (NTRS)

Ammer, R. C.; Sowers, H. D.

1977-01-01

Aerodynamic and acoustics analytical studies were conducted to evaluate three thrust reverser designs for potential use on commercial over-the-wing STOL transports. The concepts were: (1) integral D nozzle/target reverser, (2) integral D nozzle/top arc cascade reverser, and (3) post exit target reverser integral with wing. Aerodynamic flowpaths and kinematic arrangements for each concept were established to provide a 50% thrust reversal capability. Analytical aircraft stopping distance/noise trade studies conducted concurrently with flow path design showed that these high efficiency reverser concepts are employed at substantially reduced power settings to meet noise goals of 100 PNdB on a 152.4 m sideline and still meet 609.6 m landing runway length requirements. From an overall installation standpoint, only the integral D nozzle/target reverser concept was found to penalize nacelle cruise performance; for this concept a larger nacelle diameter was required to match engine cycle effective area demand in reverse thrust.

A Partitioning Algorithm for Block-Diagonal Matrices With Overlap

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

Guy Antoine Atenekeng Kahou; Laura Grigori; Masha Sosonkina

2008-02-02

We present a graph partitioning algorithm that aims at partitioning a sparse matrix into a block-diagonal form, such that any two consecutive blocks overlap. We denote this form of the matrix as the overlapped block-diagonal matrix. The partitioned matrix is suitable for applying the explicit formulation of Multiplicative Schwarz preconditioner (EFMS) described in [3]. The graph partitioning algorithm partitions the graph of the input matrix into K partitions, such that every partition {Omega}{sub i} has at most two neighbors {Omega}{sub i-1} and {Omega}{sub i+1}. First, an ordering algorithm, such as the reverse Cuthill-McKee algorithm, that reduces the matrix profile ismore » performed. An initial overlapped block-diagonal partition is obtained from the profile of the matrix. An iterative strategy is then used to further refine the partitioning by allowing nodes to be transferred between neighboring partitions. Experiments are performed on matrices arising from real-world applications to show the feasibility and usefulness of this approach.« less

Microfibres and macroscopic films from the coordination-driven hierarchical self-assembly of cylindrical micelles

PubMed Central

Lunn, David J.; Gould, Oliver E. C.; Whittell, George R.; Armstrong, Daniel P.; Mineart, Kenneth P.; Winnik, Mitchell A.; Spontak, Richard J.; Pringle, Paul G.; Manners, Ian

2016-01-01

Anisotropic nanoparticles prepared from block copolymers are of growing importance as building blocks for the creation of synthetic hierarchical materials. However, the assembly of these structural units is generally limited to the use of amphiphilic interactions. Here we report a simple, reversible coordination-driven hierarchical self-assembly strategy for the preparation of micron-scale fibres and macroscopic films based on monodisperse cylindrical block copolymer micelles. Coordination of Pd(0) metal centres to phosphine ligands immobilized within the soluble coronas of block copolymer micelles is found to induce intermicelle crosslinking, affording stable linear fibres comprised of micelle subunits in a staggered arrangement. The mean length of the fibres can be varied by altering the micelle concentration, reaction stoichiometry or aspect ratio of the micelle building blocks. Furthermore, the fibres aggregate on drying to form robust, self-supporting macroscopic micelle-based thin films with useful mechanical properties that are analogous to crosslinked polymer networks, but on a longer length scale. PMID:27538877

ATP-sensitive K/sup +/ channels that are blocked by hypoglycemia-inducing sulfonylureas in insulin-secreting cells are activated by galanin, a hyperglycemia-inducing hormone

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

de Weille, J.; Schmid-Antomarchi, H.; Fosset, M.

1988-02-01

The action of the hyperglycemia-inducing hormone galanin, a 29-amino acid peptide names from its N-terminal glycine and C-terminal amidated alanine, was studied in rat insulinoma (RINm5F) cells using electrophysiological and /sup 86/Rb/sup +/ flux techniques. Galanin hyperpolarizes and reduces spontaneous electrical activity by activating a population of APT-sensitive K/sup +/ channels with a single-channel conductance of 30 pS (at -60 mV). Galanin-induced hyperpolarization and reduction of spike activity are reversed by the hypoglycemia-inducing sulfonylurea glibenclamine. Glibenclamide blocks the galanin-activated ATP-sensitive K/sup +/ channel. /sup 86/Rb/sup +/ efflux from insulinoma cells is stimulated by galanin in a dose-dependent manner. The half-maximummore » value of activation is found at 1.6 nM. Galanin-induced /sup 86/Rb/sup +/ efflux is abolished by glibenclamide. The half-maximum value of inhibition is found at 0.3 nM, which is close to the half-maximum value of inhibition of the ATP-dependent K/sup +/ channel reported earlier. /sup 86/Rb/sup +/ efflux studies confirm the electrophysiological demonstration that galanin activates and ATP-dependent K/sup +/ channel.« less

Stabilization of Reversed Replication Forks by Telomerase Drives Telomere Catastrophe.

PubMed

Margalef, Pol; Kotsantis, Panagiotis; Borel, Valerie; Bellelli, Roberto; Panier, Stephanie; Boulton, Simon J

2018-01-25

Telomere maintenance critically depends on the distinct activities of telomerase, which adds telomeric repeats to solve the end replication problem, and RTEL1, which dismantles DNA secondary structures at telomeres to facilitate replisome progression. Here, we establish that reversed replication forks are a pathological substrate for telomerase and the source of telomere catastrophe in Rtel1 -/- cells. Inhibiting telomerase recruitment to telomeres, but not its activity, or blocking replication fork reversal through PARP1 inhibition or depleting UBC13 or ZRANB3 prevents the rapid accumulation of dysfunctional telomeres in RTEL1-deficient cells. In this context, we establish that telomerase binding to reversed replication forks inhibits telomere replication, which can be mimicked by preventing replication fork restart through depletion of RECQ1 or PARG. Our results lead us to propose that telomerase inappropriately binds to and inhibits restart of reversed replication forks within telomeres, which compromises replication and leads to critically short telomeres. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Effect of clozapine on locomotor activity and anxiety-related behavior in the neonatal mice administered MK-801.

PubMed

Pınar, Neslihan; Akillioglu, Kubra; Sefil, Fatih; Alp, Harun; Sagir, Mustafa; Acet, Ahmet

2015-08-11

Atypical antipsychotics have been used to treat fear and anxiety disturbance that are highly common in schizophrenic patients. It is suggested that disruptions of N-methyl-d-aspartate (NMDA)-mediated transmission of glutamate may underlie the pathophysiology of schizophrenia. The present study was conducted to analyze the effectiveness of clozapine on the anxiety-related behavior and locomotor function of the adult brain, which had previously undergone NMDA receptor blockade during a developmental period. In order to block the NMDA receptor, male mice were administered 0.25 mg/kg of MK-801 on days 7 to 10 postnatal. In adulthood, they were administered intraperitoneally 0.5 mg/kg of clozapine and tested with open-field and elevated plus maze test, to assess their emotional behavior and locomotor activity. In the group receiving MK-801 in the early developmental period the elevated plus maze test revealed a reduction in the anxiety-related behavior (p<0.05), while the open-field test indicated a decrease in locomotor activity (p<0.01). Despite these reductions, clozapine could not reverse the NMDA receptor blockade. Also, as an atypical antipsychotic agent, clozapine could not reverse impairment in the locomotor activity and anxiety-related behavior, induced by administration of the MK-801 in neonatal period.

Effect of clozapine on locomotor activity and anxiety-related behavior in the neonatal mice administered MK-801

PubMed Central

Pinar, Neslihan; Akillioglu, Kubra; Sefil, Fatih; Alp, Harun; Sagir, Mustafa; Acet, Ahmet

2015-01-01

Atypical antipsychotics have been used to treat fear and anxiety disturbance that are highly common in schizophrenic patients. It is suggested that disruptions of N-methyl-d-aspartate (NMDA)-mediated transmission of glutamate may underlie the pathophysiology of schizophrenia. The present study was conducted to analyze the effectiveness of clozapine on the anxiety-related behavior and locomotor function of the adult brain, which had previously undergone NMDA receptor blockade during a developmental period. In order to block the NMDA receptor, male mice were administered 0.25 mg/kg of MK-801 on days 7 to 10 postnatal. In adulthood, they were administered intraperitoneally 0.5 mg/kg of clozapine and tested with open-field and elevated plus maze test, to assess their emotional behavior and locomotor activity. In the group receiving MK-801 in the early developmental period the elevated plus maze test revealed a reduction in the anxiety-related behavior (p<0.05), while the open-field test indicated a decrease in locomotor activity (p<0.01). Despite these reductions, clozapine could not reverse the NMDA receptor blockade. Also, as an atypical antipsychotic agent, clozapine could not reverse impairment in the locomotor activity and anxiety-related behavior, induced by administration of the MK-801 in neonatal period. PMID:26295298

Lymphatic vasculature mediates macrophage reverse cholesterol transport in mice.

PubMed

Martel, Catherine; Li, Wenjun; Fulp, Brian; Platt, Andrew M; Gautier, Emmanuel L; Westerterp, Marit; Bittman, Robert; Tall, Alan R; Chen, Shu-Hsia; Thomas, Michael J; Kreisel, Daniel; Swartz, Melody A; Sorci-Thomas, Mary G; Randolph, Gwendalyn J

2013-04-01

Reverse cholesterol transport (RCT) refers to the mobilization of cholesterol on HDL particles (HDL-C) from extravascular tissues to plasma, ultimately for fecal excretion. Little is known about how HDL-C leaves peripheral tissues to reach plasma. We first used 2 models of disrupted lymphatic drainage from skin--1 surgical and the other genetic--to quantitatively track RCT following injection of [3H]-cholesterol-loaded macrophages upstream of blocked or absent lymphatic vessels. Macrophage RCT was markedly impaired in both models, even at sites with a leaky vasculature. Inhibited RCT was downstream of cholesterol efflux from macrophages, since macrophage efflux of a fluorescent cholesterol analog (BODIPY-cholesterol) was not altered by impaired lymphatic drainage. We next addressed whether RCT was mediated by lymphatic vessels from the aortic wall by loading the aortae of donor atherosclerotic Apoe-deficient mice with [2H]6-labeled cholesterol and surgically transplanting these aortae into recipient Apoe-deficient mice that were treated with anti-VEGFR3 antibody to block lymphatic regrowth or with control antibody to allow such regrowth. [2H]-Cholesterol was retained in aortae of anti-VEGFR3-treated mice. Thus, the lymphatic vessel route is critical for RCT from multiple tissues, including the aortic wall. These results suggest that supporting lymphatic transport function may facilitate cholesterol clearance in therapies aimed at reversing atherosclerosis.

Randolph AFB, San Antonio, Texas. Revised Uniform Summary of Surface Weather Observations (RUSSWO). Parts A-F.

DTIC Science & Technology

1982-02-08

is printed in any year-month block when the extreme value Is based on an in- complete month (at least one day missing for the month). When a month has...means, standard deviations, and total number of valid observations for each month and annual (all months). An asterisk (*) is printed n each data block...becomes the extreme or monthly total in any of these tables it is printed as "TRACE." Continued on Reverse Side Values ’or means and standard

Cumulative fatigue damage behavior of MAR M-247

NASA Technical Reports Server (NTRS)

Mcgaw, Michael A.; Halford, Gary R.; Kalluri, Sreeramesh

1991-01-01

The objective was to examine the room temperature fatigue and nonlinear cumulative fatigue damage behavior of the cast nickel-based superalloy, MAR M-247. The fatigue test matrix consisted of single-level, fully reversed fatigue experiments. Two series of tests were performed: one of the two baseline fatigue LCF (Low-Cycle Fatigue) life levels was used in the first loading block, and the HCF (High-Cycle Fatigue) baseline loading level was used in the second block in each series. For each series, duplicate tests were performed at each applied LCF life fraction.

Marginal Leakage of a Softened Temporary Restoration as Determined by Microorganism Penetration.

DTIC Science & Technology

1980-03-31

INSTRUCTIONSIOv AG jEO OPEIGFR -T L V L L-VACCESIN NO. 3. RECIPIENT’S CATALOG NUMBER 4. TITLE (and Subtitle arginal Leakage of a Softenedl, S . TYPE OF...microorganisms "WA . . 24. KEY WRDS (Conthie on reverse &Ade ffneceassay and idetiy by block numbe) j 20. A ’rAC’rouI~ss s -b I-----f --c y d.denif by block...vitro using an in vitro 6 dye penetration technique. Paris and associates studied the ability of test organisms (Serratis marcescens and Sarcina lutea

The Relevance of the De Broglie Velocity (V sub 1 = h/2md sub 1) to Shock Loading Induced Reactions in Lead Azide

DTIC Science & Technology

1991-09-01

CODES 18. SUBJECT TERMS (Continue on reverse if necessary and identify by block number) FIELD GROUP SUB-GROUP De Broglie Velocity Detonation Particle...Velocity Shock Induced Reaction I Lead Azide 19. ABSTRACT (Continue on reverse if necessary and identify by biock number) Availabl e experimental shock...induced reactive pressure levels for dextrinated and single crystal lead azide are compared to predicted Pv1 magnitudes. PV1 = P. CL V1 where V, = h

Mean-field studies of time reversal breaking states in super-heavy nuclei with the Gogny force

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

Robledo, L. M., E-mail: luis.robledo@uam.es

2015-10-15

Recent progress on the description of time reversal breaking (odd mass and multi-quasiparticle excitation) states in super-heavy nuclei within a mean field framework and using several flavors of the Gogny interaction is reported. The study includes ground and excited states in selected odd mass isotopes of nobelium and mendelevium as well as high K isomeric states in {sup 254}No. These are two and four-quasiparticle excitations that are treated in the same self-consistent HFB plus blocking framework as the odd mass states.

In Vitro Evaluation of Nonnucleoside Reverse Transcriptase Inhibitors UC-781 and TMC120-R147681 as Human Immunodeficiency Virus Microbicides†

PubMed Central

Van Herrewege, Yven; Michiels, Jo; Van Roey, Jens; Fransen, Katrien; Kestens, Luc; Balzarini, Jan; Lewi, Paul; Vanham, Guido; Janssen, Paul

2004-01-01

The nonnucleoside reverse transcriptase inhibitors UC-781 and TMC120-R147681 (Dapivirine) effectively prevented human immunodeficiency virus (HIV) infection in cocultures of monocyte-derived dendritic cells and T cells, representing primary targets in sexual transmission. Both drugs had a favorable therapeutic index. A 24-h treatment with 1,000 nM UC-781 or 100 nM TMC120-R147681 prevented cell-free HIV infection, whereas 10-fold-higher concentrations blocked cell-associated HIV. PMID:14693562

Heat Capacity of Spider Silk-like Block Copolymers

PubMed Central

Huang, Wenwen; Krishnaji, Sreevidhya; Hu, Xiao; Kaplan, David; Cebe, Peggy

2012-01-01

We synthesized and characterized a new family of di-block copolymers based on the amino acid sequences of Nephila clavipes major ampulate dragline spider silk, having the form HABn and HBAn (n=1–3), comprising an alanine-rich hydrophobic block, A, a glycine-rich hydrophilic block, B, and a histidine tag, H. The reversing heat capacities, Cp(T), for temperatures below and above the glass transition, Tg, were measured by temperature modulated differential scanning calorimetry. For the solid state, we then calculated the heat capacities of our novel block copolymers based on the vibrational motions of the constituent poly(amino acid)s, whose heat capacities are known or can be estimated from the ATHAS Data Bank. For the liquid state, the heat capacity was estimated by using the rotational and translational motions in the polymer chain. Excellent agreement was found between the measured and calculated values of the heat capacity, showing that this method can serve as a standard by which to assess the Cp for other biologically inspired block copolymers. The fraction of beta sheet crystallinity of spider silk block copolymers was also determined by using the predicted Cp, and was verified by wide angle X-ray diffraction and Fourier transform infrared spectroscopy. The glass transition temperatures of spider silk block copolymer were fitted by Kwei’s equation and the results indicate that attractive interaction exists between the A-block and B-block. PMID:23869111

Mesoscale assembly of chemically modified graphene into complex cellular networks

PubMed Central

Barg, Suelen; Perez, Felipe Macul; Ni, Na; do Vale Pereira, Paula; Maher, Robert C.; Garcia-Tuñon, Esther; Eslava, Salvador; Agnoli, Stefano; Mattevi, Cecilia; Saiz, Eduardo

2014-01-01

The widespread technological introduction of graphene beyond electronics rests on our ability to assemble this two-dimensional building block into three-dimensional structures for practical devices. To achieve this goal we need fabrication approaches that are able to provide an accurate control of chemistry and architecture from nano to macroscopic levels. Here, we describe a versatile technique to build ultralight (density ≥1 mg cm−3) cellular networks based on the use of soft templates and the controlled segregation of chemically modified graphene to liquid interfaces. These novel structures can be tuned for excellent conductivity; versatile mechanical response (elastic-brittle to elastomeric, reversible deformation, high energy absorption) and organic absorption capabilities (above 600 g per gram of material). The approach can be used to uncover the basic principles that will guide the design of practical devices that by combining unique mechanical and functional performance will generate new technological opportunities. PMID:24999766

Drug insight: If inhibitors as specific heart-rate-reducing agents.

PubMed

Borer, Jeffrey S

2004-12-01

Heart rate is determined primarily by spontaneously repeating net inward current carried by sodium ions and potassium ions through hyperpolarization-activated cyclic-nucleotide-gated channels. Within the heart, these channels are found most abundantly in sinoatrial cardiomyocytes. The channels open in response to membrane hyperpolarization, modulated by local cAMP concentrations. They permit activation of the I(f) current, which can be blocked specifically by molecules characterized by linked benzazepinone and benzocyclobutane rings, and which are devoid of effects on cardiac conduction, inotropy or peripheral vascular tone. The resulting heart-rate reduction has been effective in angina prevention in clinical trials involving 4,000 patients, using the prototype I(f) inhibitor, ivabradine. No serious adverse events have been attributed to the treatment; the most prominent side-effect is dose-related, always reversible and often transient visual symptoms that seldom result in voluntary drug discontinuation.

Sketched Oxide Single-Electron Transistor

NASA Astrophysics Data System (ADS)

Cheng, Guanglei

2012-02-01

Devices that confine and process single electrons represent an important scaling limit of electronics. Such devices have been realized in a variety of materials and exhibit remarkable electronic, optical and spintronic properties. Here, we use an atomic force microscope tip to reversibly ``sketch'' single-electron transistors by controlling a metal-insulator transition at the interface of two oxides.ootnotetextCheng et al., Nature Nanotechnology 6, 343 (2011). In these devices, single electrons tunnel resonantly between source and drain electrodes through a conducting oxide island with a diameter of ˜1.5 nm. We demonstrate control over the number of electrons on the island using bottom- and side-gate electrodes, and observe hysteresis in electron occupation that is attributed to ferroelectricity within the oxide heterostructure. These single-electron devices may find use as ultradense non-volatile memories, nanoscale hybrid piezoelectric and charge sensors, as well as building blocks in quantum information processing and simulation platforms.

Development of a 1000V, 200A, low-loss, fast-switching, gate-assisted turn-off thyristor

NASA Technical Reports Server (NTRS)

Schlegel, E. S.; Lowry, L. R.

1975-01-01

Feasibility was demonstrated for a thyristor that blocks 1000V forward and reverse, conducts 200A, and turns on in little more than 2 microsec with only 2A of gate drive. Its features include a turn-off time of 3 microsec achieved with 2A of gate assist current of a few microseconds duration and an energy dissipation of only 12 mJ per pulse for a 20 microsec half sine wave, 200A pulse. Extensive theoretical and experimental study of the electrical behavior of thyristors having a fast turn-off time have significantly improved the understanding of the physics of turning thyristor off. Thyristors of two new designs were fabricated and evaluated. The high speed and low power were achieved by a combination of gate amplification, cathode shunting, and gate-assisted turn-off. Two techniques for making this combination practical are described.

Chloroquine-induced cardiomyopathy: a reversible cause of heart failure.

PubMed

Yogasundaram, Haran; Hung, Whitney; Paterson, Ian D; Sergi, Consolato; Oudit, Gavin Y

2018-06-01

Chloroquine (CQ) and hydroxychloroquine (HCQ) are anti-rheumatic medications frequently used in the treatment of connective tissue disorders. We present the case of a 45-year-old woman with CQ-induced cardiomyopathy leading to severe heart failure. Electrocardiographic abnormalities included bifascicular block, while structural disease consisted of severe biventricular and biatrial hypertrophy. Appropriate diagnosis via endomyocardial biopsy led to cessation of CQ and subsequent dramatic improvement in symptoms and structural heart disease. Cardiac toxicity is an under-recognized adverse effect of CQ/HCQ leading to cardiomyopathy with concentric hypertrophy and conduction abnormalities, with the potential for significant morbidity and mortality. Predisposing factors for CQ/HCQ-induced cardiomyopathy have been proposed. CQ/HCQ cardiomyopathy is a phenocopy of Fabry disease, and α-galactosidase A polymorphism may account for some heterogeneity of disease presentation. © 2018 The Authors. ESC Heart Failure published by John Wiley & Sons Ltd on behalf of the European Society of Cardiology.

Photoinitiated Polymerization-Induced Self-Assembly of Glycidyl Methacrylate for the Synthesis of Epoxy-Functionalized Block Copolymer Nano-Objects.

PubMed

Tan, Jianbo; Liu, Dongdong; Huang, Chundong; Li, Xueliang; He, Jun; Xu, Qin; Zhang, Li

2017-08-01

Herein, a novel photoinitiated polymerization-induced self-assembly formulation via photoinitiated reversible addition-fragmentation chain transfer dispersion polymerization of glycidyl methacrylate (PGMA) in ethanol-water at room temperature is reported. It is demonstrated that conducting polymerization-induced self-assembly (PISA) at low temperatures is crucial for obtaining colloidal stable PGMA-based diblock copolymer nano-objects. Good control is maintained during the photo-PISA process with a high rate of polymerization. The polymerization can be switched between "ON" and "OFF" in response to visible light. A phase diagram is constructed by varying monomer concentration and degree of polymerization. The PGMA-based diblock copolymer nano-objects can be further cross-linked by using a bifunctional primary amine reagent. Finally, silver nanoparticles are loaded within cross-linked vesicles via in situ reduction, exhibiting good catalytic properties. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrochromic projection and writing device

DOEpatents

Branz, Howard M.; Benson, David K.

2002-01-01

A display and projection apparatus includes an electrochromic material and a photoconductive material deposited in tandem used in conjunction with a light filtering means for filtering light transmitted through the electrochromic material. When an electric field is applied across the electrochromic material and the photoconductive material, light that is incident onto the photoconductive material through the surface of the projection apparatus causes the photoconductive material to conduct current locally in proportion to the amount of light incident on the photoconductive material. The flow of current causes the underlying portions of the electrochromic material to switch from an opaque state to a clear or transmissive state, thereby allowing back-light to propagate through the electrochromic material to create a visible image on the surface of the projection apparatus. Reversal of the electric field causes the electrochromic material to revert back to its opaque state, thereby blocking the transmission of back-light and effectively erasing the image from the surface of the projection apparatus.

Morphology and conductivity of PEO-based polymers having various end functional groups

NASA Astrophysics Data System (ADS)

Jung, Ha Young; Mandal, Prithwiraj; Park, Moon Jeong

Poly(ethylene oxide) (PEO)-based polymers have been considered most promising candidates of polymer electrolytes for lithium batteries owing to the high ionic conductivity of PEO/lithium salt complexes. This positive aspect prompted researchers to investigate PEO-containing block copolymers prepared by linking mechanically robust block to PEO covalently. Given that the microphase separation of block copolymers can affect both mechanical properties and ion transport properties, various strategies have been reported to tune the morphology of PEO-containing block copolymers. In the present study, we describe a simple means for modulating the morphologies of PEO-based block copolymers with an aim to improve ion transport properties. By varying terminal groups of PEO in block copolymers, the disordered morphology can be readily transformed into ordered lamellae or gyroid phases, depending on the type and number density of end group. In particular, the existence of terminal groups resulted in a large reduction in crystallinity of PEO chains and thereby increasing room temperature ionic conductivity.

Measuring blocking force to interpret ionic mechanisms within bucky-gel actuators

NASA Astrophysics Data System (ADS)

Kruusamäe, Karl; Sugino, Takushi; Asaka, Kinji

2015-04-01

Bucky-gel laminates are tri-layer structures where polymeric electrolyte film is sandwiched between two compliant electrode layers of carbon nanotubes and ionic liquid. The resulting ionic and capacitive structures, being regarded as a type of electromechanically active polymers (EAP), have the perspective of becoming soft bending actuators in the fields such as biomimetic robotics or lab-on-chip technology. A typical electromechanical step response of a bucky-gel actuator in a cantilever configuration exhibits a fast bending displacement followed by some reverse motion referred to as the back-relaxation. It has been proposed that the bending but also the back-relaxation of bucky-gel laminates occur due to the relocation of cations and anions within the tri-layer structure. A great number of modeling about ionic EAP materials aims to predict the amplitude of free bending or the blocking force of the actuator. However, as the bucky-gel laminates are viscoelastic, the translation from generated force to bending amplitude is not always straightforward - it can take the form of an integro-differential equation with speed (i.e. the amplitude and type of the input signal) and temperature (i.e. the electronic conductivity of the material and driving current) as just some of the parameters. In this study we propose to use a so-called two carrier-model to analyze the electromechanical response of a bucky-gel actuator. After modifying the electrical equivalent circuit, the time domain response of blocking force is measured to elaborate the ionic mechanisms during the work-cycle of bucky-gel actuator.

Department of Defense In-House RDT&E Activities

DTIC Science & Technology

1986-10-30

Research Management, Air Force IResearch, Army Research . Navy Researche Research 19 ABSTRACT (Continue on reverse if necessary and identify by block...Aeromedical Research Laboratory ........................ 1 Air Defense Artillery Board ............................ 2 Airborne & Special Operations...NAVY Aerospace Medical Research Laboratory .................. 55 Air Development Center ................................. 56 Air Propulsion

Inversion in Mathematical Thinking and Learning

ERIC Educational Resources Information Center

Greer, Brian

2012-01-01

Inversion is a fundamental relational building block both within mathematics as the study of structures and within people's physical and social experience, linked to many other key elements such as equilibrium, invariance, reversal, compensation, symmetry, and balance. Within purely formal arithmetic, the inverse relationships between addition and…

Relevance of Conduction Disorders in Bachmann's Bundle During Sinus Rhythm in Humans.

PubMed

Teuwen, Christophe P; Yaksh, Ameeta; Lanters, Eva A H; Kik, Charles; van der Does, Lisette J M E; Knops, Paul; Taverne, Yannick J H J; van de Woestijne, Pieter C; Oei, Frans B S; Bekkers, Jos A; Bogers, Ad J J C; Allessie, Maurits A; de Groot, Natasja M S

2016-05-01

Bachmann's bundle (BB) is considered to be the main route of interatrial conduction and to play a role in development of atrial fibrillation (AF). The goals of this study are to characterize the presence of conduction disorders in BB during sinus rhythm and to study their relation with AF. High-resolution epicardial mapping (192 unipolar electrodes, interelectrode distance: 2 mm) of sinus rhythm was performed in 185 patients during coronary artery bypass surgery of whom 13 had a history of paroxysmal AF. Continuous rhythm monitoring was used to detect postoperative AF during the first 5 postoperative days. In 67% of the patients, BB was activated from right to left; in the remaining patients from right and middle (21%), right, central, and left (8%), or central (4%) site. Mean effective conduction velocity was 89 cm/s. Conduction block was present in most patients (75%; median 1.1%, range 0-12.8) and was higher in patients with paroxysmal AF compared with patients without a history of AF (3.2% versus 0.9%; P=0.03). A high amount of conduction block (>4%) was associated with de novo postoperative AF (P=0.02). Longitudinal lines of conduction block >10 mm were also associated with postoperative AF (P=0.04). BB may be activated through multiple directions, but the predominant route of conduction is from right to left. Conduction velocity across BB is around 90 cm/s. Conduction is blocked in both longitudinal and transverse direction in the majority of patients. Conduction disorders, particularly long lines of longitudinal conduction block, are more pronounced in patients with AF episodes. © 2016 American Heart Association, Inc.

The modulation effects of d-amphetamine and procaine on the spontaneously generated action potentials in the central neuron of snail, Achatina fulica Ferussac.

PubMed

Lin, Chia-Hsien; Tsai, Ming-Cheng

2005-05-01

The modulation effects of d-amphetamine and procaine on the spontaneously generated action potentials were studied on the RP1 central neuron of giant African snails (Achatina fulica Ferussac). Extra-cellular application of d-amphetamine or procaine reversibly elicited bursts of potential (BoP). Prazosin, propranolol, atropine or d-tubocurarine did not alter the BoP elicited by either d-amphetamine or procaine. KT-5720 or H89 (protein kinase A inhibitors) blocked d-amphetamine-elicited BoP, whereas they did not block the procaine-elicited BoP. U73122, neomycin (phospholipase C inhibitors) blocked the procaine-elicited BoP, whereas they did not block the d-amphetamine-elicited BoP in the same neuron. These results suggest that BoP elicited by d-amphetamine or procaine were associated with protein kinase A and phospholipase C activity in the neuron.

Synthesis and Self-Assembly of Block Copolymers Containing Temperature Sensitive and Degradable Chain Segments.

PubMed

Gong, Hong-Liang; Lei, Lei; Shi, Shu-Xian; Xia, Yu-Zheng; Chen, Xiao-Nong

2018-05-01

In this work, polylactide-b-poly(N-isopropylacrylamide) were synthesized by the combination of controlled ring-opening polymerization and reversible addition fragmentation chain transfer polymerization. These block copolymers with molecular weight range from 7,900 to 12,000 g/mol and narrow polydispersity (≤1.19) can self-assemble into micelles (polylactide core, poly(N-isopropylacrylamide) shell) in water at certain temperature range, which have been evidenced by laser particle size analyzer proton nuclear magnetic resonance and transmission electron microscopy. Such micelles exhibit obvious thermo-responsive properties: (1) Poly(N-isopropylacrylamide) blocks collapse on the polylactide core as system temperature increase, leading to reduce of micelle size. (2) Micelles with short poly(N-isopropylacrylamide) blocks tend to aggregate together when temperature increased, which is resulted from the reduction of the system hydrophilicity and the decreased repulsive force between micelles.

Methods And System Suppressing Clutter In A Gain-Block, Radar-Responsive Tag System

DOEpatents

Ormesher, Richard C.; Axline, Robert M.

2006-04-18

Methods and systems reduce clutter interference in a radar-responsive tag system. A radar transmits a series of linear-frequency-modulated pulses and receives echo pulses from nearby terrain and from radar-responsive tags that may be in the imaged scene. Tags in the vicinity of the radar are activated by the radar's pulses. The tags receive and remodulate the radar pulses. Tag processing reverses the direction, in time, of the received waveform's linear frequency modulation. The tag retransmits the remodulated pulses. The radar uses a reversed-chirp de-ramp pulse to process the tag's echo. The invention applies to radar systems compatible with coherent gain-block tags. The invention provides a marked reduction in the strength of residual clutter echoes on each and every echo pulse received by the radar. SAR receiver processing effectively whitens passive-clutter signatures across the range dimension. Clutter suppression of approximately 14 dB is achievable for a typical radar system.

Optically responsive supramolecular polymer glasses

NASA Astrophysics Data System (ADS)

Balkenende, Diederik W. R.; Monnier, Christophe A.; Fiore, Gina L.; Weder, Christoph

2016-03-01

The reversible and dynamic nature of non-covalent interactions between the constituting building blocks renders many supramolecular polymers stimuli-responsive. This was previously exploited to create thermally and optically healable polymers, but it proved challenging to achieve high stiffness and good healability. Here we present a glass-forming supramolecular material that is based on a trifunctional low-molecular-weight monomer ((UPyU)3TMP). Carrying three ureido-4-pyrimidinone (UPy) groups, (UPyU)3TMP forms a dynamic supramolecular polymer network, whose properties are governed by its cross-linked architecture and the large content of the binding motif. This design promotes the formation of a disordered glass, which, in spite of the low molecular weight of the building block, displays typical polymeric behaviour. The material exhibits a high stiffness and offers excellent coating and adhesive properties. On account of reversible dissociation and the formation of a low-viscosity liquid upon irradiation with ultraviolet light, rapid optical healing as well as (de)bonding on demand is possible.

Polymersome magneto-valves for reversible capture and release of nanoparticles

PubMed Central

van Rhee, P.G.; Rikken, R.S.M.; Abdelmohsen, L.K.E.A.; Maan, J.C.; Nolte, R.J.M.; van Hest, J.C.M.; Christianen, P.C.M.; Wilson, D.A.

2014-01-01

Stomatocytes are polymersomes with an infolded bowl-shaped architecture. This internal cavity is connected to the outside environment via a small ‘mouth’ region. Stomatocytes are assembled from diamagnetic amphiphilic block-copolymers with a highly anisotropic magnetic susceptibility, which permits to magnetically align and deform the polymeric self-assemblies. Here we show the reversible opening and closing of the mouth region of stomatocytes in homogeneous magnetic fields. The control over the size of the opening yields magneto-responsive supramolecular valves that are able to reversibly capture and release cargo. Furthermore, the increase in the size of the opening is gradual and starts at fields below 10 T, which opens the possibility of using these structures for delivery and nanoreactor applications. PMID:25248402

Chloride transport-driven alveolar fluid secretion is a major contributor to cardiogenic lung edema

PubMed Central

Solymosi, Esther A.; Kaestle-Gembardt, Stefanie M.; Vadász, István; Wang, Liming; Neye, Nils; Chupin, Cécile Julie Adrienne; Rozowsky, Simon; Ruehl, Ramona; Tabuchi, Arata; Schulz, Holger; Kapus, Andras; Morty, Rory E.; Kuebler, Wolfgang M.

2013-01-01

Alveolar fluid clearance driven by active epithelial Na+ and secondary Cl− absorption counteracts edema formation in the intact lung. Recently, we showed that impairment of alveolar fluid clearance because of inhibition of epithelial Na+ channels (ENaCs) promotes cardiogenic lung edema. Concomitantly, we observed a reversal of alveolar fluid clearance, suggesting that reversed transepithelial ion transport may promote lung edema by driving active alveolar fluid secretion. We, therefore, hypothesized that alveolar ion and fluid secretion may constitute a pathomechanism in lung edema and aimed to identify underlying molecular pathways. In isolated perfused lungs, alveolar fluid clearance and secretion were determined by a double-indicator dilution technique. Transepithelial Cl− secretion and alveolar Cl− influx were quantified by radionuclide tracing and alveolar Cl− imaging, respectively. Elevated hydrostatic pressure induced ouabain-sensitive alveolar fluid secretion that coincided with transepithelial Cl− secretion and alveolar Cl− influx. Inhibition of either cystic fibrosis transmembrane conductance regulator (CFTR) or Na+-K+-Cl− cotransporters (NKCC) blocked alveolar fluid secretion, and lungs of CFTR−/− mice were protected from hydrostatic edema. Inhibition of ENaC by amiloride reproduced alveolar fluid and Cl− secretion that were again CFTR-, NKCC-, and Na+-K+-ATPase–dependent. Our findings show a reversal of transepithelial Cl− and fluid flux from absorptive to secretory mode at hydrostatic stress. Alveolar Cl− and fluid secretion are triggered by ENaC inhibition and mediated by NKCC and CFTR. Our results characterize an innovative mechanism of cardiogenic edema formation and identify NKCC1 as a unique therapeutic target in cardiogenic lung edema. PMID:23645634

Block Copolymer Electrolytes: Thermodynamics, Ion Transport, and Use in Solid- State Lithium/Sulfur Cells

NASA Astrophysics Data System (ADS)

Teran, Alexander Andrew

Nanostructured block copolymer electrolytes containing an ion-conducting block and a modulus-strengthening block are of interest for applications in solid-state lithium metal batteries. These materials can self-assemble into well-defined microstructures, creating conducting channels that facilitate ion transport. The overall objective of this dissertation is to gain a better understanding of the behavior of salt-containing block copolymers, and evaluate their potential for use in solid-state lithium/sulfur batteries. Anionically synthesized polystyrene-b-poly(ethylene oxide) (SEO) copolymers doped with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt were used as a model system. This thesis investigates the model system on several levels: from fundamental thermodynamic studies to bulk characterization and finally device assembly and testing. First, the thermodynamics of neat and salt-containing block copolymers was studied. The addition of salt to these materials is necessary to make them conductive, however even small amounts of salt can have significant effects on their phase behavior, and consequently their iontransport and mechanical properties. As a result, the effect of salt addition on block copolymer thermodynamics has been the subject of significant interest over the last decade. A comprehensive study of the thermodynamics of block copolymer/salt mixtures over a wide range of molecular weights, compositions, salt concentrations and temperatures was conducted. Next, the effect of molecular weight on ion transport in both homopolymer and copolymer electrolytes were studied over a wide range of chain lengths. Homopolymer electrolytes show an inverse relationship between conductivity and chain length, with a plateau in the infinite molecular weight limit. This is due to the presence of two mechanisms of ion conduction in homopolymers; the first mechanism is a result of the segmental motion of the chains surrounding the salt ions, 2 creating a liquid-like environment around the ion while the second mechanism of ion conduction is attributed to diffusion of the entire polymer chain with coordinated ions. Equilibrated block copolymer electrolytes exhibit a non-monotonic dependence on molecular weight, decreasing with increasing molecular weight in the small molecular weight limit before increasing when molecular weight exceeds about 10 kg mol-1. Conductivity in annealed electrolytes was shown to be affected by two competing factors: the glass transition temperature of the insulating polystyrene block and the width of the conducting poly(ethylene oxide) (PEO) channel. In the low molecular weight limit, all ions are in contact with both polystyrene (PS) and PEO segments. The intermixing between PS and PEO segments is restricted to an interfacial zone of width of about 5 nm. The fraction of ions affected by the interfacial zone decreases as the conducting channel width increases. Furthermore, the effect of thermal history on the conductivity of the block copolymer electrolytes was examined. Results suggest that long-range order impedes ion transport, and consequently decreases in conductivity of up to 80% were seen upon annealing. The effect of morphology on ion transport was studied by conducting simultaneous impedance and X-ray scattering experiments as the block copolymer electrolyte transitioned from an ordered lamellar structure to a disordered phase. The ionic conductivity increased discontinuously through the transition from order to disorder. A simple framework for quantifying the magnitude of the discontinuity was presented. Finally, block copolymer electrolytes were examined specifically for use in high energy density solid state lithium/sulfur batteries. Such materials have been shown to form a stable interface with lithium metal anodes, maintain intimate contact upon cycling, and have sufficiently high shear moduli to retard dendrite formation. Having previously satisfied the concerns associated with the lithium metal anode, the compatibility of the sulfur cathode was explored. The sulfur cathode presents many unique challenges, including the generation of soluble lithium polysulfides (Li2Sx, 2 ≤ x ≤ 8) during discharge. The solubility of such species in block copolymers and their effect on morphology was examined. The lithium polysulfides were found to exhibit similar solubility in the block copolymers as in typical organic electrolytes, however induced unusual and unexpected phase behavior in the block copolymers. Inspired by successful efforts to physically confine the soluble lithium polysulfides via nanostructured carbon-sulfur composites in the cathode, our nanostructured block copolymer electrolytes were employed in full electrochemical cells with a lithium metal anode and sulfur cathode. Different cathode compositions, electrolyte additives, and cell architectures were tested. Surprisingly, the polysulfides diffused readily from the cathode through the block copolymer electrolyte, and the normally robust SEO|Li metal interface was detrimentally affected their presence during cycling. The polysulfides appeared to change the mechanical properties of the electrolyte such that intimate contact with the lithium metal was lost. Several promising strategies to overcome this problem were investigated and offer exciting avenues for improvement for future researchers. (Abstract shortened by UMI.).

Electrically conductive doped block copolymer of polyacetylene and polyisoprene

DOEpatents

Aldissi, Mahmoud

1985-01-01

An electrically conductive block copolymer of polyisoprene and polyacetyl and a method of making the same are disclosed. The polymer is prepared by first polymerizing isoprene with n-butyllithium in a toluene solution to form an active isoprenyllithium polymer. The active polymer is reacted with an equimolar amount of titanium butoxide and subsequently exposed to gaseous acetylene. A block copolymer of polyisoprene and polyacetylene is formed. The copolymer is soluble in common solvents and may be doped with I.sub.2 to give it an electrical conductivity in the metallic regime.

Small domain-size multiblock copolymer electrolytes

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

Pistorino, Jonathan; Eitouni, Hany Basam

2016-09-20

New block polymer electrolytes have been developed which have higher conductivities than previously reported for other block copolymer electrolytes. The new materials are constructed of multiple blocks (>5) of relatively low domain size. The small domain size provides greater protection against formation of dendrites during cycling against lithium in an electrochemical cell, while the large total molecular weight insures poor long range alignment, which leads to higher conductivity. In addition to higher conductivity, these materials can be more easily synthesized because of reduced requirements on the purity level of the reagents.

Recovery of laryngeal nerve function with sugammadex after rocuronium-induced profound neuromuscular block.

PubMed

Pavoni, Vittorio; Gianesello, Lara; Martinelli, Cristiana; Horton, Andrew; Nella, Alessandra; Gori, Gabriele; Simonelli, Martina; De Scisciolo, Giuseppe

2016-09-01

The aim of this study was to evaluate the efficacy of sugammadex in reversing profound rocuronium-induced neuromuscular block at the laryngeal adductor muscles using motor-evoked potentials (mMEPs). A prospective observational study. University surgical center. Twenty patients with American Society of Anesthesiologists physical class I-II status who underwent propofol-remifentanil anesthesia for the surgery of the thyroid gland. Patients were enrolled for reversal of profound neuromuscular block (sugammadex 16 mg/kg, 3 minutes after rocuronium 1.2 mg/kg). To prevent laryngeal nerve injury during the surgical procedures, all patients underwent neurophysiologic monitoring using mMEPs from vocal muscles. At the same time, the registration of TOF-Watch acceleromyograph at the adductor pollicis muscle response to ulnar nerve stimulation was performed; recovery was defined as a train-of-four (TOF) ratio ≥0.9. After injection of 16 mg/kg of sugammadex, the mean time to recovery of the basal mMEPs response at the laryngeal adductor muscles was 70 ± 18.2 seconds. The mean time to recovery of the TOF ratio to 0.9 was 118 ± 80 seconds. In the postoperative period, 12 patients received follow-up evaluation of the vocal cords and no lesions caused by the surface laryngeal electrode during electrophysiological monitoring were noted. Recovery from profound rocuronium-induced block on the larynx is fast and complete with sugammadex. In urgent scenarios, "early" extubation can be performed, even with a TOF ratio ≤0.9. However, all procedures to prevent postoperative residual curarization should still be immediately undertaken. Copyright © 2016 Elsevier Inc. All rights reserved.

Systemic morphine blocks the seizures induced by intracerebroventricular (i.c.v.) injections of opiates and opioid peptides.

PubMed

Urca, G; Frenk, H

1982-08-19

Intracerebroventricular (i.c.v.) injections of the endorphins and of morphine in rats produce highly characteristic, naloxone sensitive, electrographic seizures. In contrast, systemic injections of morphine have been shown to exert a marked anticonvulsant effect. The present study demonstrates that systemic morphine pretreatment can prevent the occurrence of electrographic seizures injected by i.c.v. morphine, Leu-enkephalin and beta-endorphin and that the anti-epileptic effect of morphine can be reversed by naloxone. Male albino rats, previously prepared for chronic i.c.v. injections and EEG recordings, were pretreated with 0--100 mg/kg of intraperitoneal (i.p.) morphine. Thirty five minutes later morphine (520 nmol), Leu-enkephalin (80 nmol) or beta-endorphin (5 nmol) were injected i.c.v. Pretreatment with i.p. morphine blocked the occurrence of seizures induced by morphine and both endogenous opioids. Lower doses of systemic morphine (50 mg/kg) were necessary to block i.c.v. morphine seizures than the dose (100 mg/kg) necessary to block seizures induced by i.c.v. Leu-enkephalin and beta-endorphin. Naloxone (1 mg/kg) administered 25 min following 50 mg/kg of i.p. morphine and preceding the injections of i.c.v. morphine reversed the antiepileptic effect of systemic morphine. These results demonstrate the possible existence of two opiate sensitive systems, one with excitatory-epileptogenic effects and the other possessing inhibitory-antiepileptic properties. The possible relationship between these findings and the known heterogeneity of opiate receptors and opiate actions is discussed.

Ultrasound-guided genicular nerve block for pain control after total knee replacement: Preliminary case series and technical note.

PubMed

González Sotelo, V; Maculé, F; Minguell, J; Bergé, R; Franco, C; Sala-Blanch, X

2017-12-01

Total knee arthroplasty (TKA) is an operation with moderate to severe postoperative pain. The Fast-Track models employ local infiltration techniques with anaesthetics at high volumes (100-150ml). We proposed a genicular nerve block with low volume of local anaesthetic. The aim of our study is to evaluate the periarticular distribution of these blocks in a fresh cadaver model and to describe the technique in a preliminary group of patients submitted to TKA. In the anatomical phase, 4 genicular nerves (superior medial, superior lateral, inferior medial and inferior lateral) were blocked with 4ml of local anaesthetic with iodinated contrast and methylene blue in each (16ml in total). It was performed on a fresh cadaver and the distribution of the injected medium was evaluated by means of a CT-scan and coronal anatomical sections on both knees. The clinical phase included 12 patients scheduled for TKA. Ultrasound-guided block of the 4 genicular nerves was performed preoperatively and their clinical efficacy evaluated by assessing pain after the reversal of the spinal block and at 12h after the block. Pain was measured using the numerical scale and the need for rescue analgesia was evaluated. A wide periarticular distribution of contrast was observed by CT-scan, which was later evaluated in the coronal sections. The distribution followed the joint capsule without entering the joint, both in the femur and in the tibia. The pain after the reversal of the subarachnoid block was 2±1, requiring rescue analgesia in 42% of the patients. At 12h, the pain according to the numerical scale was 4±1, 33% required rescue analgesia. The administration of 4ml of local anaesthetic at the level of the 4 genicular nerves of the knee produces a wide periarticular distribution. Our preliminary data in a series of 12 patients undergoing TKA seems to be clinically effective. Nevertheless, extensive case series and comparative studies with local infiltration techniques with anaesthetics are needed to support these encouraging results. Copyright © 2017 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.

Use of Ionic Liquids in Rod-Coil Block Copolyimides for Improved Lithium Ion Conduction

NASA Technical Reports Server (NTRS)

Meador, Mary Ann B.; Tigelaar, Dean M.; Chapin, Kara; Bennett, William R.

2007-01-01

Solvent-free, solid polymer electrolytes (SPE) have the potential to improve safety, increase design flexibility and enhance performance of rechargeable lithium batteries. Solution based electrolytes are flammable and typically incompatible with lithium metal anodes, limiting energy density. We have previously demonstrated use of polyimide rod coil block copolymers doped with lithium salts as electrolytes for lithium polymer batteries. The polyimide rod blocks provide dimensional stability while the polyethylene oxide (PEO) coil portions conduct ions. Phase separation of the rods and coils in these highly branched polymers provide channels with an order of magnitude improvement in lithium conduction over polyethylene oxide itself at room temperature. In addition, the polymers have been demonstrated in coin cells to be compatible with lithium metal. For practical use at room temperature and below, however, at least an order of magnitude improvement in ion conduction is still required. The addition of nonvolatile, room temperature ionic liquids has been shown to improve the ionic conductivity of high molecular weight PEO. Herein we describe use of these molten salts to improve ionic conductivity in the rod-coil block copolymers.

Reversal of neuromuscular block with sugammadex: a comparison of the corrugator supercilii and adductor pollicis muscles in a randomized dose-response study.

PubMed

Yamamoto, S; Yamamoto, Y; Kitajima, O; Maeda, T; Suzuki, T

2015-08-01

Neuromuscular monitoring using the corrugator supercilii muscle is associated with a number of challenges. The aim of this study was to assess reversal of a rocuronium-induced neuromuscular blockade with sugammadex according to monitoring either using the corrugator supercilii muscle or the adductor pollicis muscle. We hypothesized that a larger dose of sugammadex would be required to obtain a train-of-four (TOF) ratio of 1.0 with the corrugator supercilii muscle than with the adductor pollicis muscle. Forty patients aged 20-60 years and 40 patients aged ≥ 70 years were enrolled. After induction of anesthesia, we recorded the corrugator supercilii muscle response to facial nerve stimulation and the adductor pollicis muscle response to ulnar nerve stimulation using acceleromyography. All patients received 1 mg/kg rocuronium. When the first twitch (T1) of TOF recovered to 10% of control values at the corrugator supercilii, rocuronium infusion was commenced to maintain a T1 of 10% of the control at the corrugator supercilii. Immediately after discontinuation of rocuronium infusion, 2 mg/kg or 4 mg/kg of sugammadex was administered. The time for recovery to a TOF ratio of 1.0 and the number of patients not reaching a TOF ratio of 1.0 by 5 min at each dose and muscle was recorded. When neuromuscular block at the corrugator supercilii was maintained at a T1 of 10% of control, that at the adductor pollicis was deep (post-tetanic count ≤ 5). Sugammadex 4 mg/kg completely antagonized neuromuscular block at both muscles within 5 min. The time to a TOF ratio of 1.0 at the adductor pollicis was significantly longer in the group ≥ 70 years than the group 20-60 years (mean (SD): 178 (42.8) s vs. 120 (9.4) s, P < 0.0001). In contrast, 2 mg/kg sugammadex reversed neuromuscular blockade at the corrugator supercilii but not at the adductor pollicis, with 10 patients in the group 20-60 years and 8 patients in the group ≥ 70 years requiring an additional sugammadex (P < 0.05 vs. 4 mg/kg sugammadex). Sugammadex 4 mg/kg was required to reverse a moderate rocuronium-induced neuromuscular block when the corrugator supercilii muscle is used for monitoring. © 2015 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Sugammadex compared with neostigmine/glycopyrrolate for routine reversal of neuromuscular block: a systematic review and economic evaluation†

PubMed Central

Paton, F.; Paulden, M.; Chambers, D.; Heirs, M.; Duffy, S.; Hunter, J. M.; Sculpher, M.; Woolacott, N.

2010-01-01

Summary The cost-effectiveness of sugammadex for the routine reversal of muscle relaxation produced by rocuronium or vecuronium in UK practice is uncertain. We performed a systematic review of randomized controlled trials of sugammadex compared with neostigmine/glycopyrrolate and an economic assessment of sugammadex for the reversal of moderate or profound neuromuscular block (NMB) produced by rocuronium or vecuronium. The economic assessment aimed to establish the reduction in recovery time and the ‘value of time saved’ which would be necessary for sugammadex to be potentially cost-effective compared with existing practice. Three trials indicated that sugammadex 2 mg kg−1 (4 mg kg−1) produces more rapid recovery from moderate (profound) NMB than neostigmine/glycopyrrolate. The economic assessment indicated that if the reductions in recovery time associated with sugammadex in the trials are replicated in routine practice, sugammadex would be cost-effective if those reductions are achieved in the operating theatre (assumed value of staff time, £4.44 per minute), but not if they are achieved in the recovery room (assumed value of staff time, £0.33 per minute). However, there is considerable uncertainty in these results. Sugammadex has the potential to be cost-effective compared with neostigmine/glycopyrrolate for the reversal of rocuronium-induced moderate or profound NMB, provided that the time savings observed in trials can be achieved and put to productive use in clinical practice. Further research is required to evaluate the effects of sugammadex on patient safety, predictability of recovery from NMB, patient outcomes, and efficient use of resources. PMID:20935005

Blocking and reversing hepatic fibrosis in patients with chronic hepatitis B treated by traditional Chinese medicine (tablets of biejia ruangan or RGT): study protocol for a randomized controlled trial.

PubMed

Qu, Jianhui; Yu, Zujiang; Li, Qin; Chen, Yongping; Xiang, Dedong; Tan, Lin; Lei, Chunliang; Bai, Wenlin; Li, Hongyan; Shang, Qinghua; Chen, Liang; Hu, Xiaoyu; Lu, Wei; Li, Zhiqin; Chen, Da; Wang, Xiaodong; Zhang, Changjiang; Xiao, Guangming; Qi, Xun; Chen, Jing; Zhou, Li; Chen, Guofeng; Li, Yonggang; Zeng, Zhen; Rong, Guanghua; Dong, Zheng; Chen, Yan; Lou, Min; Wang, Chunping; Lu, Yinying; Zhang, Cuihong; Yang, Yongping

2014-11-10

Chronic hepatitis B (CHB) can progress to cirrhosis, hepatocellular carcinoma (HCC) and ultimately liver-related death. Although oral antiviral therapy for patients with CHB reduces the risk of such complications, once cirrhosis is established, the benefits of antiviral therapy are not robustly demonstrated. According to traditional Chinese medicine (TCM), some Chinese herbal medicines promote blood circulation and soften hard masses, and therefore they may block and reverse hepatic fibrosis. The aim of this study is to evaluate the effects of TCM tablets of the compound biejia ruangan (RGT) administered for fibrosis, and entecavir (ETV), on the development of HCC in patients with CHB or hepatitis B virus (HBV)-related compensated cirrhosis. This multicenter, centrally randomized, double-blind, placebo-controlled, parallel-group study is planned to complete within 5 years. For the study, 1,000 with CHB or HBV-related compensated cirrhosis are randomly assigned in a 1:1 ratio to a treatment group (0.5 mg ETV once daily; 2 g RGT three times daily) or a control group (0.5 mg ETV once daily; 2 g RGT dummy agent three times daily). The primary end points are the development of HCC and liver-related death. Secondary end points include disease progression and overall survival. Although antiviral therapy can achieve sustained suppression of HBV replication, thereby preventing cirrhosis, patients with CHB treated with nucleos(t)ide analogs (NUCs) retain a higher risk for HCC compared with patients with inactive disease. Although previous clinical trials with RGT have confirmed the efficacy of blocking and reversing hepatic fibrosis in patients with CHB or compensated cirrhosis, the long-term risk for HCC or disease progression in these patients treated with combination of RGT and NUCs compared with NUCs alone is unclear. Therefore, it is necessary to investigate the effects of the RGT blockade and reversal of hepatic fibrosis on the development of HCC in patients with CHB or HBV-related compensated cirrhosis in large, prospective, multicenter, double-blind, randomized, controlled trials in China. ClinicalTrials.gov Identifier: NCT01965418. Date registered: 17 October 2013.

Large Block Test Final Report

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

Lin, W

2001-12-01

This report documents the Large-Block Test (LBT) conducted at Fran Ridge near Yucca Mountain, Nevada. The LBT was a thermal test conducted on an exposed block of middle non-lithophysal Topopah Spring tuff (Tptpmn) and was designed to assist in understanding the thermal-hydrological-mechanical-chemical (THMC) processes associated with heating and then cooling a partially saturated fractured rock mass. The LBT was unique in that it was a large (3 x 3 x 4.5 m) block with top and sides exposed. Because the block was exposed at the surface, boundary conditions on five of the six sides of the block were relatively wellmore » known and controlled, making this test both easier to model and easier to monitor. This report presents a detailed description of the test as well as analyses of the data and conclusions drawn from the test. The rock block that was tested during the LBT was exposed by excavation and removal of the surrounding rock. The block was characterized and instrumented, and the sides were sealed and insulated to inhibit moisture and heat loss. Temperature on the top of the block was also controlled. The block was heated for 13 months, during which time temperature, moisture distribution, and deformation were monitored. After the test was completed and the block cooled down, a series of boreholes were drilled, and one of the heater holes was over-cored to collect samples for post-test characterization of mineralogy and mechanical properties. Section 2 provides background on the test. Section 3 lists the test objectives and describes the block site, the site configuration, and measurements made during the test. Section 3 also presents a chronology of events associated with the LBT, characterization of the block, and the pre-heat analyses of the test. Section 4 describes the fracture network contained in the block. Section 5 describes the heating/cooling system used to control the temperature in the block and presents the thermal history of the block during the test. Sections 5 through 9 report the measurements made on the block during the preheating, heating, and cooling phases. These measurements include temperature, thermal conductivity and diffusivity, hydrological measurements (electrical resistivity, neutron logging, gas pressure, and relative humidity), geomechanics, selected chemical analyses, and microbial activity. These sections also include analyses and simulations of the block behavior. Finally, conclusions are presented in Section 10. Complete data sets were submitted during the time the test was conducted. The data tracking numbers (DTNs) of all of the data are presented in Table 1-1.« less

Cardiac tissue geometry as a determinant of unidirectional conduction block: assessment of microscopic excitation spread by optical mapping in patterned cell cultures and in a computer model.

PubMed

Fast, V G; Kléber, A G

1995-05-01

Unidirectional conduction block (UCB) and reentry may occur as a consequence of an abrupt tissue expansion and a related change in the electrical load. The aim of this study was to evaluate critical dimensions of the tissue necessary for establishing UCB in heart cell culture. Neonatal rat heart cell cultures with cell strands of variable width emerging into a large cell area were grown using a technique of patterned cell growth. Action potential upstrokes were measured using a voltage sensitive dye (RH-237) and a linear array of 10 photodiodes with a 15 microns resolution. A mathematical model was used to relate action potential wave shapes to underlying ionic currents. UCB (block of a single impulse in anterograde direction - from a strand to a large area - and conduction in the retrograde direction) occurred in narrow cell strands with a width of 15(SD 4) microns (1-2 cells in width, n = 7) and there was no conduction block in strands with a width of 31(8) microns (n = 9, P < 0.001) or larger. The analysis of action potential waveshapes indicated that conduction block was either due to geometrical expansion alone (n = 5) or to additional local depression of conduction (n = 2). In wide strands, action potential upstrokes during anterograde conduction were characterised by multiple rising phases. Mathematical modelling showed that two rising phases were caused by electronic current flow, whereas local ionic current did not coincide with the rising portions of the upstrokes. (1) High resolution optical mapping shows multiphasic action potential upstrokes at the region of abrupt expansion. At the site of the maximum decrement in conduction, these peaks were largely determined by the electrotonus and not by the local ionic current. (2) Unidirectional conduction block occurred in strands with a width of 15(4) microns (1-2 cells).

The acetylcholinesterase inhibitor BW284c51 is a potent blocker of Torpedo nicotinic AchRs incorporated into the Xenopus oocyte membrane

PubMed Central

Olivera-Bravo, Silvia; Ivorra, Isabel; Morales, Andrés

2004-01-01

This work was aimed to determine if 1,5-bis(4-allyldimethylammoniumphenyl)pentan-3-one dibromide (BW284c51), the most selective acetylcholinesterase inhibitor (AchEI), affects the nicotinic acetylcholine (Ach) receptor (AchR) function. Purified Torpedo nicotinic AchRs were injected into Xenopus laevis oocytes and BW284c51 effects on Ach- and carbamylcholine (Cch)-elicited currents were assessed using the voltage-clamp technique. BW284c51 (up to 1 mM) did not evoke any change in the oocyte membrane conductance. When BW284c51 (10 pM–100 μM) and Ach were coapplied, Ach-evoked currents (IAch) were reversibly inhibited in a concentration-dependent manner (Hill coefficient, 1; IC50, 0.2–0.5 μM for 0.1–1000 μM Ach). Cch-elicited currents showed a similar inhibition by BW284c51. IAch blockade by BW284c51 showed a strong voltage dependence, being only apparent at hyperpolarising potentials. BW284c51 also enhanced IAch desensitisation. BW284c51 changed the Ach concentration-dependence curve of Torpedo AchR response from two-site to single-site kinetics, without noticeably affecting the EC50 value. The BW284c51 blocking effect was highly selective for nicotinic over muscarinic receptors. BW284c51 inhibition potency was stronger than that of tacrine, and similar to that of d-tubocurarine (d-TC). Coapplication of BW284c51 with either tacrine or d-TC revealed synergistic inhibitory effects. Our results indicate that BW284c51 antagonises nicotinic AchRs in a noncompetitive way by blocking the receptor channel, and possibly by other, yet unknown, mechanisms. Therefore, besides acting as a selective AchEI, BW284c51 constitutes a powerful and reversible blocker of nicotinic AchRs that might be used as a valuable tool for understanding their function. PMID:15644872

Syngas production over La 0.9Ni yAl 11.95-yO 19-δ catalysts during C 14-alkane partial oxidation: Effects of sulfur and polycyclic aromatic hydrocarbons

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

Gardner, Todd H.

Partial oxidation studies were conducted over a series of Ni-substituted lanthanum hexaaluminate catalysts, La 0.9Ni yAl 11.95-yO 19-δ (y = 1.0, 0.8, 0.4 and 0.2) to evaluate the effect of higher alkane, sulfur and polycyclic aromatic hydrocarbons using tetradecane (n-C 14), dibenzothiophene (DBT) and 1-methylnapthalene (1-MN) as model reaction compounds. XRD showed the Ni-substituted lanthanum hexaaluminate catalysts to have magnetoplumbite structure. Lattice parameters along the a,b-axis are shown to increase systematically with increasing Ni substitution. The unit cell is also shown to increase systematically with Ni substitution providing clear evidence of Ni 2+ substitution for Al 3+ in the lanthanummore » hexaaluminate lattice. Catalytic activity and product yields were evaluated by temperature programmed surface reaction (TPSR) using n-C 14 partial oxidation as a probe reaction. Between 750 and 900°C, H 2 and CO yields are shown to increase with increasing Ni surface sites while aromatic and olefin yields are shown to decrease. Step response experiments were performed to show the effect of 0.1 wt% 1-MN addition on catalytic activity and performance. As expected, at lower Ni substitution, thermal chemistry predominates suggesting fewer available active Ni sites. At the conditions tested, the site blocking effect is shown to be reversible at all levels of Ni substitution. Similar catalytic behaviors are observed with step response experiments to 50 ppm w/w dibenzothiophene (DBT) where site blocking is shown to produce a concomitantly greater effect on catalytic performance and active site occlusion with catalysts that have less active sites. The step response to DBT is also observed to be reversible. Post analysis of the used catalysts shows that coke deposition is greater on the catalysts with lower Ni substitution.« less

Syngas production over La 0.9Ni yAl 11.95-yO 19-δ catalysts during C 14-alkane partial oxidation: Effects of sulfur and polycyclic aromatic hydrocarbons

DOE PAGES

Gardner, Todd H.

2018-02-07

Partial oxidation studies were conducted over a series of Ni-substituted lanthanum hexaaluminate catalysts, La 0.9Ni yAl 11.95-yO 19-δ (y = 1.0, 0.8, 0.4 and 0.2) to evaluate the effect of higher alkane, sulfur and polycyclic aromatic hydrocarbons using tetradecane (n-C 14), dibenzothiophene (DBT) and 1-methylnapthalene (1-MN) as model reaction compounds. XRD showed the Ni-substituted lanthanum hexaaluminate catalysts to have magnetoplumbite structure. Lattice parameters along the a,b-axis are shown to increase systematically with increasing Ni substitution. The unit cell is also shown to increase systematically with Ni substitution providing clear evidence of Ni 2+ substitution for Al 3+ in the lanthanummore » hexaaluminate lattice. Catalytic activity and product yields were evaluated by temperature programmed surface reaction (TPSR) using n-C 14 partial oxidation as a probe reaction. Between 750 and 900°C, H 2 and CO yields are shown to increase with increasing Ni surface sites while aromatic and olefin yields are shown to decrease. Step response experiments were performed to show the effect of 0.1 wt% 1-MN addition on catalytic activity and performance. As expected, at lower Ni substitution, thermal chemistry predominates suggesting fewer available active Ni sites. At the conditions tested, the site blocking effect is shown to be reversible at all levels of Ni substitution. Similar catalytic behaviors are observed with step response experiments to 50 ppm w/w dibenzothiophene (DBT) where site blocking is shown to produce a concomitantly greater effect on catalytic performance and active site occlusion with catalysts that have less active sites. The step response to DBT is also observed to be reversible. Post analysis of the used catalysts shows that coke deposition is greater on the catalysts with lower Ni substitution.« less

Ion Conduction in Microphase-Separated Block Copolymer Electrolytes

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

Kambe, Yu; Arges, Christopher G.; Patel, Shrayesh

2017-01-01

Microphase separation of block copolymers provides a promising route towards engineering a mechanically robust ion conducting film for electrochemical devices. The separation into two different nano-domains enables the film to simultaneously exhibit both high ion conductivity and mechanical robustness, material properties inversely related in most homopolymer and random copolymer electrolytes. To exhibit the maximum conductivity and mechanical robustness, both domains would span across macroscopic length scales enabling uninterrupted ion conduction. One way to achieve this architecture is through external alignment fields that are applied during the microphase separation process. In this review, we present the progress and challenges for aligningmore » the ionic domains in block copolymer electrolytes. A survey of alignment and characterization is followed by a discussion of how the nanoscale architecture affects the bulk conductivity and how alignment may be improved to maximize the number of participating conduction domains.« less

Simulation Study to Improve Focalization of a Figure Eight Coil by Using a Conductive Shield Plate and a Ferromagnetic Block.

PubMed

Zhao, Chen; Zhang, Shunqi; Liu, Zhipeng; Yin, Tao

2015-07-01

A new method to improve the focalization and efficiency of the Figure of Eight (FOE) coil in rTMS is discussed in this paper. In order to decrease the half width of the distribution curve (HWDC), as well to increase the ratio of positive peak value to negative peak value (RPN) of the induced electric field, a shield plate with a window and a ferromagnetic block are assumed to enhance the positive peak value of the induced electrical field. The shield is made of highly conductive copper, and the block is made of highly permeable soft magnetic ferrite. A computer simulation is conducted on ANSYS® software to conduct the finite element analysis (FEA). Two comparing coefficients were set up to optimize the sizes of the shield window and the block. Simulation results show that a shield with a 60 mm × 30 mm sized window, together with a block 40 mm thick, can decrease the focal area of a FOE coil by 46.7%, while increasing the RPN by 135.9%. The block enhances the peak value of the electrical field induced by a shield-FOE by 8.4%. A real human head model was occupied in this paper to further verify our method.

Effects of strychnine on the potassium conductance of the frog node of Ranvier

PubMed Central

1977-01-01

The nature of the block of potassium conductance by strychnine in frog node of Ranvier was investigated. The block is voltage-dependent and reaches a steady level with a relaxation time of 1 to several ms. Block is increased by depolarization or a reduction in [K+]O as well as by increasing strychnine concentration. A quaternary derivative of strychnine produces a similar block only when applied intracellularly. In general and in detail, strychnine block resembles that produced by intracellular application of the substituted tetraethylammonium compounds extensively studied by C.M. Armstrong (1969. J. Gen Physiol. 54:553-575. 1971. J. Gen. Physiol. 58:413-437). The kinetics, voltage dependence, and dependence on [K+]O of strychnine block are of the same form. It is concluded that tertiary strychnine must cross the axon membrane and block from the axoplasmic side in the same fashion as these quaternary amines. PMID:302320

Room Air Conditioners; Appliance Repair--Advanced: 9027.04.

ERIC Educational Resources Information Center

Dade County Public Schools, Miami, FL.

This Quinmester course includes installations, electrical and mechanical servicing, reverse cycle air conditioning, malfunctions, troubleshooting and repair, discharge, pump down, and recharging the system. The course may be taught as a two or three Quinmester credit course. In each instance the course consists of six instructional blocks:…

Jackknife Variance Estimator for Two Sample Linear Rank Statistics

DTIC Science & Technology

1988-11-01

Accesion For - - ,NTIS GPA&I "TIC TAB Unann c, nc .. [d Keywords: strong consistency; linear rank test’ influence function . i , at L By S- )Distribut...reverse if necessary and identify by block number) FIELD IGROUP SUB-GROUP Strong consistency; linear rank test; influence function . 19. ABSTRACT

Restoration of normal phenotype in cancer cells

DOEpatents

Bissell, M.J.; Weaver, V.M.

1998-12-08

A method for reversing expression of malignant phenotype in cancer cells is described. The method comprises applying {beta}{sub 1} integrin function-blocking antibody to the cells. The method can be used to assess the progress of cancer therapy. Human breast epithelial cells were shown to be particularly responsive. 14 figs.

Toxicology of High Energy Fuels

DTIC Science & Technology

1981-12-01

side If necessary and identify by block number) High energy fuels ALCM Cruise missile fuels Toxi col ogy JP-9 ൜. ABSTRACT (Continue on reverse side if...exposed to gasoline . Further research is ongoing to assess the applicability of the male rat as an animal model in hydrocarbon caused nephrotoxicity. 4

Method for restoration of normal phenotype in cancer cells

DOEpatents

Bissell, Mina J.; Weaver, Valerie M.

2000-01-01

A method for reversing expression of malignant phenotype in cancer cells is described. The method comprises applying .beta..sub.1 integrin function-blocking antibody to the cells. The method can be used to assess the progress of cancer therapy. Human breast epithelial cells were shown to be particularly responsive.

Restoration of normal phenotype in cancer cells

DOEpatents

Bissell, Mina J.; Weaver, Valerie M.

1998-01-01

A method for reversing expression of malignant phenotype in cancer cells is described. The method comprises applying .beta..sub.1 integrin function-blocking antibody to the cells. The method can be used to assess the progress of cancer therapy. Human breast epithelial cells were shown to be particularly responsive.

Research and Diagnostic Applications of Monoclonal Antibodies to Coccidioides immitis.

DTIC Science & Technology

1985-01-01

for Human and Animal Mycology , Georgia, May 1985. 17. COSATI CODES 18. SUBJECT TERMS (Co tinue on reverse if necessary and identify by block number...IX Congress of the International Society for Human and Animal Mycology , Atlanta GA, May 1985. ISHAM START ’IResearch and Diagnostic Applications of

A truly Lego®-like modular microfluidics platform

NASA Astrophysics Data System (ADS)

Vittayarukskul, Kevin; Lee, Abraham Phillip

2017-03-01

Ideally, a modular microfluidics platform should be simple to assemble and support 3D configurations for increased versatility. The modular building blocks should also be mass producible like electrical components. These are fundamental features of world-renowned Legos® and why Legos® inspire many existing modular microfluidics platforms. In this paper, a truly Lego®-like microfluidics platform is introduced, and its basic feasibility is demonstrated. Here, PDMS building blocks resembling 2  ×  2 Lego® bricks are cast from 3D-printed master molds. The blocks are pegged and stacked on a traditional Lego® plate to create simple, 3D microfluidic networks, such as a single basket weave. Characteristics of the platform, including reversible sealing and automatic alignment of channels, are also analyzed and discussed in detail.

Field-induced assembly of colloidal ellipsoids into well-defined microtubules

PubMed Central

Crassous, Jérôme J.; Mihut, Adriana M.; Wernersson, Erik; Pfleiderer, Patrick; Vermant, Jan; Linse, Per; Schurtenberger, Peter

2014-01-01

Current theoretical attempts to understand the reversible formation of stable microtubules and virus shells are generally based on shape-specific building blocks or monomers, where the local curvature of the resulting structure is explicitly built-in via the monomer geometry. Here we demonstrate that even simple ellipsoidal colloids can reversibly self-assemble into regular tubular structures when subjected to an alternating electric field. Supported by model calculations, we discuss the combined effects of anisotropic shape and field-induced dipolar interactions on the reversible formation of self-assembled structures. Our observations show that the formation of tubular structures through self-assembly requires much less geometrical and interaction specificity than previously thought, and advance our current understanding of the minimal requirements for self-assembly into regular virus-like structures. PMID:25409686

Moisture and Thermal Conductivity of Lightweight Block Walls

NASA Astrophysics Data System (ADS)

Joosep, R.

2015-11-01

This article examines thermal properties of lightweight block walls and their changes over the course of time. Three different types of lightweight blocks and two types of heat insulation are used in construction. Aeroc aerated concrete blocks are in use, as well as compacted LECA (Lightweight Expanded Clay Aggregate) Fibo blocks made from burned clay and Silbet blocks produced from oil shale ash. Expanded Thermisol EPS60F polystyrene plates and glass wool Isover OL-P plates are used for thermal insulation. The actual and computational values of thermal conductivity and the water draining properties of walls over time are compared in this article. Water draining from glass wool walls is relatively fast. Water-draining can take over a year in polystyrene insulated walls. All four wall constructions can be used as external walls, but care must be taken regarding the moisture content of the blocks during construction (the construction should be handled with care to minimise the moisture in the blocks), especially in polystyrene board-insulated walls.

Properties of the calcium-activated chloride current in heart.

PubMed

Zygmunt, A C; Gibbons, W R

1992-03-01

We used the whole cell patch clamp technique to study transient outward currents of single rabbit atrial cells. A large transient current, IA, was blocked by 4-aminopyridine (4AP) and/or by depolarized holding potentials. After block of IA, a smaller transient current remained. It was completely blocked by nisoldipine, cadmium, ryanodine, or caffeine, which indicates that all of the 4AP-resistant current is activated by the calcium transient that causes contraction. Neither calcium-activated potassium current nor calcium-activated nonspecific cation current appeared to contribute to the 4AP-resistant transient current. The transient current disappeared when ECl was made equal to the pulse potential; it was present in potassium-free internal and external solutions. It was blocked by the anion transport blockers SITS and DIDS, and the reversal potential of instantaneous current-voltage relations varied with extracellular chloride as predicted for a chloride-selective conductance. We concluded that the 4AP-resistant transient outward current of atrial cells is produced by a calcium-activated chloride current like the current ICl(Ca) of ventricular cells (1991. Circulation Research. 68:424-437). ICl(Ca) in atrial cells demonstrated outward rectification, even when intracellular chloride concentration was higher than extracellular. When ICa was inactivated or allowed to recover from inactivation, amplitudes of ICl(Ca) and ICa were closely correlated. The results were consistent with the view that ICl(Ca) does not undergo independent inactivation. Tentatively, we propose that ICl(Ca) is transient because it is activated by an intracellular calcium transient. Lowering extracellular sodium increased the peak outward transient current. The current was insensitive to the choice of sodium substitute. Because a recently identified time-independent, adrenergically activated chloride current in heart is reduced in low sodium, these data suggest that the two chloride currents are produced by different populations of channels.

Epigenetic Basis for the Regulation of Estrogen Receptor Alpha Activity in Breast Cancer Cells

DTIC Science & Technology

2009-04-01

B) GPER and TESK2 expression after CARM1 silencing in MCF7 was determined by reverse transcription-qPCR and revealed the requirement for CARM1 in...the E2-induced repression of GPER and TESK2. siLUC was used as a control. *, P 0.05; **, P 0.01; ***, P 0.001. (C) Enrichment of Ec3 cluster...sites (blue blocks) near GPER and TESK2 E2-downregulated target genes (red blocks). 3416 LUPIEN ET AL. MOL. CELL. BIOL. at A C Q S E R V IC E /S E R IA

Electrically conductive doped block copolymer of polyacetylene and polyisoprene. [Soluble in organic solvents

DOEpatents

Aldissi, M.

1984-06-27

An electrically conductive block copolymer of polyisoprene and polyacetylene and a method of making the same are disclosed. The polymer is prepared by first polymerizing isoprene with n-butyllithium in a toluene solution to form an active isoprenyllithium polymer. The active polymer is reacted with an equimolar amount of titanium butoxide and subsequently exposed to gaseous acetylene. A block copolymer of polyisoprene and polyacetylene is formed. The copolymer is soluble in common solvents and may be doped with I/sub 2/ to give it an electrical conductivity in the metallic regime.

Formation and Characterization of Anisotropic Block Copolymer Gels

NASA Astrophysics Data System (ADS)

Liaw, Chya Yan; Joester, Derk; Burghardt, Wesley; Shull, Kenneth

2012-02-01

Cylindrical micelles formed from block copolymer solutions closely mimic biological fibers that are presumed to guide mineral formation during biosynthesis of hard tissues like bone. The goal of our work is to use acrylic block copolymers as oriented templates for studying mineral formation reactions in model systems where the structure of the underlying template is well characterized and reproducible. Self-consistent mean field theory is first applied to investigate the thermodynamically stable micellar morphologies as a function of temperature and block copolymer composition. Small-angle x-ray scattering, optical birefringence and shear rheometry are used to study the morphology development during thermal processing. Initial experiments are based on a thermally-reversible alcohol-soluble system that can be converted to an aqueous gel by hydrolysis of a poly(t-butyl methacrylate) block to a poly(methacrylic acid) block. Aligned cylindrical domains are formed in the alcohol-based system when shear is applied in an appropriate temperature regime, which is below the critical micelle temperature but above the temperature at which the relaxation time of the gels becomes too large. Processing strategies for producing the desired cylindrical morphologies are being developed that account for both thermodynamic and kinetic effects.

Cholesterol blocks spontaneous insertion of membrane proteins into liposomes of phosphatidylcholine.

PubMed

Nakamura, Shota; Suzuki, Sonomi; Saito, Hiroaki; Nishiyama, Ken-Ichi

2018-04-01

Spontaneous insertion of membrane proteins into liposomes formed from Escherichia coli polar phospholipids is blocked by diacylglycerol (DAG) at a physiological level. We found that cholesterol also blocks this spontaneous insertion, although a much larger amount is necessary for sufficient blockage. Reversely, sphingomyelin enhanced the spontaneous insertion. DAG at a physiological level was found not to block spontaneous insertion into liposomes formed from phosphatidylcholine (PC), while non-physiologically high concentrations of DAG reduced it. On the other hand, cholesterol blocked the spontaneous insertion into PC liposomes at a physiological level, explaining that both PC and cholesterol are absent in E. coli. While sphingomyelin did not enhance spontaneous insertion into PC liposomes, the effect of cholesterol on blockage of spontaneous insertion was dominant over that of sphingomyelin, suggesting that cholesterol functions as a blocker of disordered spontaneous insertion in eukaryotic cells. Lower amount of cholesterol was necessary to block spontaneous insertion into ER-mimic liposomes, explaining that ER membranes contain less amount of cholesterol. These results also explain that cholesterol, but not DAG, is involved in blockage of spontaneous insertion in eukaryotic cells, since DAG plays an important role as a second messenger in signal transduction.

Photoconductivity enhancement and charge transport properties in ruthenium-containing block copolymer/carbon nanotube hybrids.

PubMed

Lo, Kin Cheung; Hau, King In; Chan, Wai Kin

2018-04-05

Functional polymer/carbon nanotube (CNT) hybrid materials can serve as a good model for light harvesting systems based on CNTs. This paper presents the synthesis of block copolymer/CNT hybrids and the characterization of their photocurrent responses by both experimental and computational approaches. A series of functional diblock copolymers was synthesized by reversible addition-fragmentation chain transfer polymerizations for the dispersion and functionalization of CNTs. The block copolymers contain photosensitizing ruthenium complexes and modified pyrene-based anchoring units. The photocurrent responses of the polymer/CNT hybrids were measured by photoconductive atomic force microscopy (PCAFM), from which the experimental data were analyzed by vigorous statistical models. The difference in photocurrent response among different hybrids was correlated to the conformations of the hybrids, which were elucidated by molecular dynamics simulations, and the electronic properties of polymers. The photoresponse of the block copolymer/CNT hybrids can be enhanced by introducing an electron-accepting block between the photosensitizing block and the CNT. We have demonstrated that the application of a rigorous statistical methodology can unravel the charge transport properties of these hybrid materials and provide general guidelines for the design of molecular light harvesting systems.

Time-reversal-symmetric single-photon wave packets for free-space quantum communication.

PubMed

Trautmann, N; Alber, G; Agarwal, G S; Leuchs, G

2015-05-01

Readout and retrieval processes are proposed for efficient, high-fidelity quantum state transfer between a matter qubit, encoded in the level structure of a single atom or ion, and a photonic qubit, encoded in a time-reversal-symmetric single-photon wave packet. They are based on controlling spontaneous photon emission and absorption of a matter qubit on demand in free space by stimulated Raman adiabatic passage. As these processes do not involve mode selection by high-finesse cavities or photon transport through optical fibers, they offer interesting perspectives as basic building blocks for free-space quantum-communication protocols.

A Study to Design a Functional Space Utilization Program for Implementation at the United States Army Medical Department Activity, Fort Benning, Georgia.

DTIC Science & Technology

1980-04-01

on reverse if necessary and identify by block number) FIELD GROUP SUB-GROUP FACILITY PLANNING; SPACE UTILIZATION 19. ABSTRACT (Continue on reverse if...potential for development. The civilian must compete for the acquisi- tion of real estate in an open market, but once acquired is relatively free to develop...gQ , i, P : -~~~~~~.. -dA A- -- 4 - - - - - - - J 4W 4" -r’- t 12 Hospital was opened in 1958, there have been 12 different commanders. Hospital

Neotectonic deformation model of the Northern Algeria from Paleomagnetic data

NASA Astrophysics Data System (ADS)

Derder, M. E. M.; Henry, B.; Maouche, S.; Amenna, M.; Bayou, B.; Djellit, H.; Ymel, H.; Gharbi, S.; Abtout, A.; Ayache, M.

2012-04-01

The seismic activity of the Western Mediterranean area is partly concentrated in northern Africa, particularly in northern Algeria, as it is shown by the strongest recent earthquakes of "Zemmouri" 21 May 2003 Mw=6.9 and the "El Asnam" 10 October 1980 Ms= 7.3. This seismicity is due to the tectonic activity related to the convergence between Africa and Eurasia plates since at least the Oligocene. The deformation is mostly compressional with associated folds, strike-slip faults and thrusts, and a direction of shortening between N-S and NNW-SSE. This convergence involves a tectonic transpression which is expressed by active deformation along the plate boundary. In northern Algeria, the seismicity is concentrated in a coastal E-W thin band zone (the Tell Atlas). Active structures define there NE-SW trending folds and NE-SW sinistral transpressive faults, which affect the intermountain and coastal Neogene to Quaternary sedimentary basins (e.g. " Cheliff "basin, " Mitidja "basin, …). These reverse faults are associated with NW-SE to E-W strike-slips deep faults. The active tectonics could be explained by a simple blocks rotation kinematics model. In order to test the validity of this kinematic model, three different paleomagnetic studies have been conducted. The first one concerned the "Cheliff" basin where sedimentary Neogene formations were extensively sampled (66 sites). The second study was carried out on Miocene andesite and dacite rocks cropping out along the northern coastal zone of the "Cheliff" basin ("Beni Haoua" area, 19 sites). The third study has been carried out on the Miocene magmatic rocks (rhyolites and basalts) cropping out north-eastern part of the "Mitidja" basin ("Cap Djinet" - "Boumerdes" area, 23 sites). The obtained results show existence of paleomagnetic clockwise rotations in all the studied areas and then validates the kinematics block rotation model. Accordingly, the deformation related to the convergence between the Africa and Eurasia plates, is partly accommodated in northern Algeria by blocks rotation movements. It seems that the Tellian Atlas (northern Algeria) domain is organized as tectonic blocks with relative clockwise blocks rotation movement as in a "bookshelf" model.

Case report: an electrocardiogram of spontaneous pneumothorax mimicking arm lead reversal.

PubMed

Wieters, J Scott; Carlin, Joseph P; Morris, Andrew

2014-05-01

There are several previously documented findings for electrocardiograms (ECGs) of spontaneous pneumothorax. These findings include axis deviation, T-wave inversion, and right bundle branch block. When an ECG has the arm leads incorrectly placed, the ECG will display right axis deviation and inversion of the P waves in lead I. There have been no previously published ECGs of spontaneous pneumothorax that have shown the same findings as reversal of the limb leads of an ECG. A possible finding of spontaneous pneumothorax is an identical finding to that of an ECG that has been flagged for limb lead reversal. A patient presented in the emergency setting with acute chest pain and shortness of breath caused by a tension pneumothorax. An ECG was administered; findings indicated reversal of the arm leads (right axis deviation and inverted P waves in lead I), but there was no actual limb lead reversal present. ECG findings resolved upon resolution of the pneumothorax. If a patient presents with chest pain and shortness of breath, and the patient's ECG is flagged for limb lead reversal despite being set up correctly, the physician should raise clinical suspicion for a possible spontaneous pneumothorax. Copyright © 2014 Elsevier Inc. All rights reserved.

Voltage-clamp study of the activation currents and fast block to polyspermy in the egg of Xenopus laevis.

PubMed

Glahn, David; Nuccitelli, Richard

2003-04-01

Voltage-clamped mature, jelly-intact Xenopus eggs were used to carefully examine the ionic currents crossing the plasma membrane before, during, and after fertilization. The bulk of the fertilization current was transient, of large amplitude, and reversed at the predicted Cl- reversal potential. However, the large amplitude fertilization current was preceded by a small, step-like increase in holding current. This small increase in holding current is referred to in this paper as Ion to acknowledge its qualitative similarity to the Ion current previously described in the sea urchin. It was observed in both fertilized and artificially activated eggs, and was found to be unaffected by 10 mm tetra-ethyl ammonium (TEA), a concentration found to block K+ currents in Rana pipiens. Current-voltage relationships are presented for the large fertilization potential, and show that the fertilization currents have a marked outward rectification and are voltage sensitive. These properties are in contrast to the total lack of rectification and slight voltage sensitivity seen before or after the fertilization currents. The time required for sperm to fertilize the egg was found to be voltage dependent with a relatively more depolarized voltage requiring a longer time for fertilization to occur. The percentage of eggs blocked with varying potential levels was determined and this information was fitted to a modified Boltzmann equation having a midpoint of -9 mV.

Adenosine Triphosphate (ATP) Inhibits Voltage-Sensitive Potassium Currents in Isolated Hensen's Cells and Nifedipine Protects Against Noise-Induced Hearing Loss in Guinea Pigs.

PubMed

Ye, Rui; Liu, Jun; Jia, Zhiying; Wang, Hongyang; Wang, YongAn; Sun, Wei; Wu, Xuan; Zhao, Zhifei; Niu, Baolong; Li, Xingqi; Dai, Guanghai; Li, Jianxiong

2016-06-13

BACKGROUND There is increasing evidence that adenosine triphosphate (ATP), a well-known neurotransmitter and neuromodulator in the central nervous system, plays an important role as an extracellular chemical messenger in the cochlea. MATERIAL AND METHODS Using a whole-cell recording technique, we studied the effects of ATP on isolated Hensen's cells, which are supporting cells in the cochlea, to determine if they are involved in the transduction of ions with hair cells. RESULTS ATP (0.1-10 µM) reduced the potassium current (IK+) in the majority of the recorded Hensen's cells (21 out of 25 cells). An inward current was also induced by high concentrations of ATP (100 µM to 10 mM), which was reversibly blocked by 100 µM suramin (a purinergic antagonist) and blocked by nifedipine (an L-type calcium channel blocker). After the cochleas were perfused with artificial perilymph solutions containing nifedipine and exposed to noise, the amplitude increase in the compound action potential (CAP) threshold and the reduction in cochlear microphonics was lower than when they were exposed to noise alone. CONCLUSIONS Our results suggest that ATP can block IK+ channels at a low concentration and induce an inward Ca2+ current at high concentrations, which is reversed by purinergic receptors. Nifedipine may have a partially protective effect on noise-induced hearing loss (NIHL).

Effects of procaine on a central neuron of the snail, Achatina fulica Ferussac.

PubMed

Lin, Chia-Hsien; Tsai, Ming-Cheng

2005-02-18

Effects of procaine on a central neuron (RP1) of the giant African snail (Achatina fulica Ferussac) were studied pharmacologically. The RP1 neuron showed spontaneous firing of action potential. Extra-cellular application of procaine (10 mM) reversibly elicited bursts of potential. The bursts of potential elicited by procaine were not blocked after administration of (1) prazosin, propranolol, atropine, d-tubocurarine, (2) calcium-free solution, (3) ryanodine (4) pretreatment with KT-5720 or chelerythrine. The bursts of potential elicited by procaine were blocked by adding U73122 (10 microM) and the bursts of potential were decreased if physiological sodium ion was replaced with lithium ion or incubated with either neomycin (3.5 mM) or high magnesium solution (30 mM). Preatment with U73122 (10 microM) blocked the initiation of bursts of potential. Ruthenium red (100 microM) or caffeine (10 mM) facilitated the procaine-elicited bursts of potential. It is concluded that procaine reversibly elicits bursts of potential in the central snail neuron. This effect was not directly related to (1) the extra-cellular calcium ion fluxes, (2) the ryanodine sensitive calcium channels in the neuron, or (3) the PKC or PKA related messenger systems. The procaine-elicited bursts of potential were associated with the phospholipase activity and the calcium mobilization in the neuron.

Actions of (-)-baclofen on rat dorsal horn neurons.

PubMed

Kangrga, I; Jiang, M C; Randić, M

1991-10-25

The actions of a gamma-aminobutyric acid B (GABAB) agonist, (-)-baclofen, on the electrophysiological properties of neurons and synaptic transmission in the spinal dorsal horn (laminae I-IV) were examined by using intracellular recordings in spinal cord slice from young rats. In addition, the effects of baclofen on the dorsal root stimulation-evoked outflow of glutamate and aspartate from the spinal dorsal horn were examined by using high performance liquid chromatography (HPLC) with flourimetric detection. Superfusion of baclofen (5 nM to 10 microM) hyperpolarized, in a stereoselective and bicuculline-insensitive manner, the majority (86%) of tested neurons. The hyperpolarization was associated with a decrease in membrane resistance and persisted in a nominally zero-Ca2+, 10 mM Mg(2+)- or a TTX-containing solution. Our findings indicate that the hyperpolarizing effect of baclofen is probably due to an increase in conductance to potassium ions. Baclofen decreased the direct excitability of dorsal horn neurons, enhanced accommodation of spike discharge, and reduced the duration of Ca(2+)-dependent action potentials. Baclofen depressed, or blocked, excitatory postsynaptic potentials evoked by electrical stimulation of the dorsal roots. Spontaneously occurring synaptic potentials were also reversibly depressed by baclofen. Whereas baclofen did not produce any consistent change in the rate of the basal outflow of glutamate and aspartate, the stimulation-evoked release of the amino acids was blocked. The present results suggest that baclofen, by activating GABAB receptors, may modulate spinal afferent processing in the superficial dorsal horn by at least two mechanisms: (1) baclofen depresses excitatory synaptic transmission primarily by a presynaptic mechanism involving a decrease in the release of excitatory amino acids, and (2) at higher concentrations, the hyperpolarization and increased membrane conductance may contribute to the depressant effect of baclofen on excitatory synaptic transmission in the rat spinal dorsal horn.

Glucose oxidation is critical for CD4+ T cell activation in a mouse model of systemic lupus erythematosus1

PubMed Central

Yin, Yiming; Choi, Seung-Chul; Xu, Zhiwei; Zeumer, Leilani; Kanda, Nathalie; Croker, Byron P.; Morel, Laurence

2015-01-01

We have previously shown that CD4+ T cells from B6.Sle1.Sle2.Sle3 (TC) lupus mice and patients present a high cellular metabolism, and a treatment combining 2-deoxyglucose (2DG), which inhibits glucose metabolism, and metformin, which inhibits oxygen consumption, normalized lupus T cell functions in vitro and reverted disease in mice. We obtained similar results with B6.lpr mice, another model of lupus, and showed that a continuous treatment is required to maintain the beneficial effect of metabolic inhibitors. Further, we investigated the relative roles of glucose oxidation and pyruvate reduction into lactate in this process.. Treatments of TC mice with either 2DG or metformin were sufficient to prevent autoimmune activation, while their combination was necessary to reverse the process. Treatment of TC mice with dichloroacetate (DCA), an inhibitor of lactate production, failed to effectively prevent or reverse autoimmune pathology. In vitro, CD4+ T cell activation upregulated the expression of genes that favor oxidative phosphorylation. Blocking glucose oxidation inhibited both IFNγ and IL-17 production, which could not be achieved by blocking pyruvate reduction. Overall, our data shows that targeting glucose oxidation is required to prevent or reverse lupus development in mice, which cannot be achieved by simply targeting the pyruvate-lactate conversion. PMID:26608911

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

Bean, Bruce Palmer

The effects of ether and halothane on membrane currents in the voltage clamped crayfish giant axon membrane were investigated. Concentrations of ether up to 300 mM and of halothane up to 32 mM had no effect on resting potential or leakage conductance. Ether and halothane reduced the size of sodium currents without changing the voltage dependence of the peak currents or their reversal potential. Ether and halothane also produced a reversible, dose-dependent speeding of sodium current decay at all membrane potentials. Ether reduced the time constants for inactivation, and also shifted the midpoint of the steady-state inactivation curve in themore » hyperpolarizing direction. Potassium currents were smaller with ether present, with no change in the voltage dependence of steady-state currents. The activation of potassium channels was faster with ether present. There was no apparent change in the capacitance of the crayfish giant axon membrane with ether concentrations of up to 100 mM. Experiments on sodium channel inactivation kinetics were performed using 4-aminopyridine to block potassium currents. Sodium currents decayed with a time course generally fit well by a single exponential. The time constant of decay was a steep function of voltage, especially in the negative resistance region of the peak current vs voltage relation.The time course of inactivation was very similar to that of the decay of the current at the same potential. The measurement of steady-state inactivation curves with different test pulses showed no shifts along the voltage asix. The voltage-dependence of the integral of sodium conductance was measured to test models of sodium channel inactivation in which channels must open before inactivating; the results appear inconsistent with some of the simplest cases of such models.« less

Feasibility of blocking detection in observations from radio occultation

NASA Astrophysics Data System (ADS)

Brunner, Lukas; Steiner, Andrea Karin; Scherllin-Pirscher, Barbara; Jury, Martin

2015-04-01

Blocking describes an atmospheric situation in which the climatological westerly flow at mid latitudes is weakened or reversed. This is caused by a persistent high pressure system which can be stationary for several days to weeks. In the Northern Hemisphere blocking preferably occurs over the Atlantic/European and the Pacific regions. In recent years blocking has been under close scientific investigation due to its effect on weather extremes, triggering heat waves in summer and cold spells in winter. So far, scientific literature mainly focused on the investigation of blocking in reanalysis and global climate model data sets. However, blocking is underestimated in most climate models due to small-scale processes involved in its evolution. For a detection of blocking, most commonly applied methods are based on the computation of meridional geopotential height gradients at the 500 hPa level. Therefore measurements with adequate vertical, horizontal, and temporal resolution and coverage are required. We use an observational data set based on Global Positioning System (GPS) Radio Occultation (RO) measurements fulfilling these requirements. RO is a relatively new, satellite based remote sensing technique, delivering profiles of atmospheric parameters such as geopotential height, pressure, and temperature. It is characterized by favorable properties like long-term stability, global coverage, and high vertical resolution. Our data set is based on the most recent WEGC RO retrieval. Here we report on a feasibility study for blocking detection and analysis in RO data for two exemplary blocking events: the blocking over Russia in summer 2010 and the blocking over Greenland in late winter 2013. For these two events about 700 RO measurements per day are available in the Northern Hemisphere. We will show that the measurement density and quality of RO observations are favorable for blocking analysis and can therefore contribute to blocking research.

Reversible electric-field manipulation of the adsorption morphology and magnetic anisotropy of small Fe and Co clusters on graphene

NASA Astrophysics Data System (ADS)

Tanveer, M.; Dorantes-Dávila, J.; Pastor, G. M.

2017-12-01

First-principles electronic calculations show how the adsorption morphology, orbital magnetism, and magnetic anisotropy energy (MAE) of small CoN and FeN clusters (N ≤3 ) on graphene (G) can be reversibly controlled under the action of an external electric field (EF). A variety of cluster-specific and EF-induced effects are revealed, including (i) perpendicular or canted adsorption configurations of the dimers and trimers, (ii) significant morphology-dependent permanent dipole moments and electric susceptibilities, (iii) EF-induced reversible transitions among the different metastable adsorption morphologies of Fe3 and Co3 on graphene, (iv) qualitative changes in the MAE landscape driven by structural changes, (v) colossal values of the magnetic anisotropy Δ E ≃45 meV per atom in Co2/G , (vi) EF-induced spin-reorientation transitions in Co3/G , and (vii) reversibly tunable coercive field and blocking temperatures, which in some cases allow a barrierless magnetization reversal of the cluster. These remarkable electric and magnetic fingerprints open new possibilities of characterizing and exploiting the size- and structural-dependent properties of magnetic nanostructures at surfaces.

Electrical conduction along endothelial cell tubes from mouse feed arteries: confounding actions of glycyrrhetinic acid derivatives

PubMed Central

Behringer, Erik J; Socha, Matthew J; Polo-Parada, Luis; Segal, Steven S

2012-01-01

BACKGROUND AND PURPOSE Electrical conduction along endothelium of resistance vessels has not been determined independently of the influence of smooth muscle, surrounding tissue or blood. Two interrelated hypotheses were tested: (i) Intercellular conduction of electrical signals is manifest in endothelial cell (EC) tubes; and (ii) Inhibitors of gap junction channels (GJCs) have confounding actions on EC electrical and Ca2+ signalling. EXPERIMENTAL APPROACH Intact EC tubes were isolated from abdominal muscle feed (superior epigastric) arteries of C57BL/6 mice. Hyperpolarization was initiated with indirect (ACh) and direct (NS309) stimulation of intermediate- and small-conductance Ca2+-activated K+ channels (IKCa/SKCa). Remote membrane potential (Vm) responses to intracellular current injection defined the length constant (λ) for electrical conduction. Dye coupling was evaluated following intracellular microinjection of propidium iodide. Intracellular Ca2+ dynamics were determined using Fura-2 photometry. Carbenoxolone (CBX) or β-glycyrrhetinic acid (βGA) was used to investigate the role of GJCs. KEY RESULTS Steady-state Vm of ECs was −25 mV. ACh and NS309 hyperpolarized ECs by −40 and −60 mV respectively. Electrical conduction decayed monoexponentially with distance (λ∼1.4 mm). Propidium iodide injected into one EC spread into surrounding ECs. CBX or βGA inhibited dye transfer, electrical conduction and EC hyperpolarization reversibly. Both agents elevated resting Ca2+ while βGA inhibited responses to ACh. CONCLUSIONS AND IMPLICATIONS Individual cells were effectively coupled to each other within EC tubes. Inhibiting GJCs with glycyrrhetinic acid derivatives blocked hyperpolarization mediated by IKCa/SKCa channels, regardless of Ca2+ signalling, obviating use of these agents in distinguishing key determinants of electrical conduction along the endothelium. PMID:22168386

Pupils' Error on the Concept of Reversibility in Solving Arithmetic Problems

ERIC Educational Resources Information Center

Maf'ulah, Syarifatul; Juniati, Dwi; Siswono, Tatag Yuli Eko

2016-01-01

The fact that there is no much study on reversibility is one of reason this study was conducted. Others, the importance of reversibility is also being researcher's motivation for focusing pupils' reversibility. On the other hand, the concern on pupils' reversibility is a major concern. The objective of this research is to identify errors done by…

High-concentration graphene dispersion stabilized by block copolymers in ethanol.

PubMed

Perumal, Suguna; Lee, Hyang Moo; Cheong, In Woo

2017-07-01

This article describes a comprehensive study for the preparation of graphene dispersions by liquid-phase exfoliation using amphiphilic diblock copolymers; poly(ethylene oxide)-block-poly(styrene) (PEO-b-PS), poly(ethylene oxide)-block-poly(4-vinylpyridine) (PEO-b-PVP), and poly(ethylene oxide)-block-poly(pyrenemethyl methacrylate) (PEO-b-PPy) with similar block lengths. Block copolymers were prepared from PEO using the Steglich coupling reaction followed by reversible addition-fragmentation chain transfer (RAFT) polymerization. Graphite platelets (G) and reduced graphene oxide (rGO) were used as graphene sources. The dispersion stability of graphene in ethanol was comparatively investigated by on-line turbidity, and the graphene concentration in the dispersions was determined gravimetrically. Our results revealed that the graphene dispersions with PEO-b-PVP were much more stable and included graphene with fewer defects than that with PEO-b-PS or PEO-b-PPy, as confirmed by turbidity and Raman analyses. Gravimetry confirmed that graphene concentrations up to 1.7 and 1.8mg/mL could be obtained from G and rGO dispersions, respectively, using PEO-b-PVP after one week. Distinctions in adhesion forces of PS, VP, PPy block units with graphene surface and the variation in solubility of the block copolymers in ethanol medium significantly affected the stability of the graphene dispersion. Copyright © 2017 Elsevier Inc. All rights reserved.

The conduction block produced by oxcarbazepine in the isolated rat sciatic nerve: a comparison with lamotrigine.

PubMed

Guven, Mustafa; Kahraman, Ibrahim; Koc, Filiz; Bozdemir, Hacer; Sarica, Yakup; Gunay, Ismail

2011-01-01

Oxcarbazepine is an antiepileptic drug widely used for the treatment of neuropathic pain. In the present study, the effects of oxcarbazepine and lamotrigine on conduction properties in the rat sciatic nerves were examined. The experiments were conducted with in vitro sucrose-gap technique on the isolated wistar rat sciatic nerves. The compound action potentials were obtained by tonic (single) and phasic (10, 40, and 100 Hz) stimulation. Oxcarbazepine produced a significant concentration- and frequency-dependent reduction in the compound action potential amplitude. When the two drugs were applied at concentrations that produced equal levels of tonic (i.e., non-frequency-dependent) conduction block, oxcarbazepine produced the greatest phasic (i.e., frequency-dependent) conduction block, followed by lamotrigine. Oxcarbazepine and lamotrigine reduced the 4-aminopyridine-induced amplitude of delayed depolarization; however, oxcarbazepine had a significantly greater effect than lamotrigine. These results suggest that oxcarbazepine produces more potent frequency-dependent conduction block than lamotrigine, and suppresses the delayed depolarization which contributes to sensory signaling and may play a role in neuropathic pain. The findings provide insight into the mechanisms of action of oxcarbazepine and lamotrigine and may help in the development of novel therapies for neuropathic pain.

Prevention and reversal of latent sensitization of dorsal horn neurons by glial blockers in a model of low back pain in male rats.

PubMed

Zhang, Juanjuan; Mense, Siegfried; Treede, Rolf-Detlef; Hoheisel, Ulrich

2017-10-01

In an animal model of nonspecific low back pain, recordings from dorsal horn neurons were made to investigate the influence of glial cells in the central sensitization process. To induce a latent sensitization of the neurons, nerve growth factor (NGF) was injected into the multifidus muscle; the manifest sensitization to a second NGF injection 5 days later was used as a read-out. The sensitization manifested in increased resting activity and in an increased proportion of neurons responding to stimulation of deep somatic tissues. To block microglial activation, minocycline was continuously administered intrathecally starting 1 day before or 2 days after the first NGF injection. The glia inhibitor fluorocitrate that also blocks astrocyte activation was administrated 2 days after the first injection. Minocycline applied before the first NGF injection reduced the manifest sensitization after the second NGF injection to control values. The proportion of neurons responsive to stimulation of deep tissues was reduced from 50% to 17.7% ( P < 0.01). No significant changes occurred when minocycline was applied after the first injection. In contrast, fluorocitrate administrated after the first NGF injection reduced significantly the proportion of neurons with deep input (15.8%, P < 0.01). A block of glia activation had no significant effect on the increased resting activity. The data suggest that blocking microglial activation prevented the NGF-induced latent spinal sensitization, whereas blocking astrocyte activation reversed it. The induction of spinal neuronal sensitization in this pain model appears to depend on microglia activation, whereas its maintenance is regulated by activated astrocytes. NEW & NOTEWORTHY Activated microglia and astrocytes mediate the latent sensitization induced by nerve growth factor in dorsal horn neurons that receive input from deep tissues of the low back. These processes may contribute to nonspecific low back pain. Copyright © 2017 the American Physiological Society.

Relations between the structure of storage and the transport of chemical compounds in karstic aquifers

NASA Astrophysics Data System (ADS)

Vaute, L.; Drogue, C.; Garrelly, L.; Ghelfenstein, M.

1997-12-01

Study of the movement of chemical compounds naturally present in the water, or which result from pollution, are examined according to the reservoir structure in karstic aquifers. Structure is represented by a simple geometrical model; slow flow takes place in blocks with a network of low-permeability cracks. The blocks are separated by highly permeable karstic conduits that allow rapid flow, and these form the aquifer drainage system. The karst studied covers 110 km 2. It is fed by an interrupted stream draining a 35 km 2 non-karstic basin, contaminated at the entry to the karst by effluents from a sewage treatment station. The underground water reappears as a resurgence with an annual average flow of approximately 1 m 3 s -1, after an apparent underground course of 8 km in the karst. Several local sources of pollution (effluent from septic tanks) contaminate the underground water during its course. Sixteen measurement operations were performed at 12 water points, between the interrupted stream and the spring. Some sampling points were at drains, and others were in the low-permeability fissured blocks. Comparison at each point of the concentrations of 14 chemical compounds gave the following results: when pollutant discharge occurs in a permeable zone, movement is rapid in the drainage network formed by the karstic conduits, and does not reach the less permeable fissured blocks which are thus protected; however, if discharge is in a low-permeability zone, the flow does not allow rapid movement of the polluted water, and this increases the pollutant concentration at the discharge. This simple pattern can be upset by a reversal of the apparent piezometric gradient between a block and a conduit during floods or pumping; this may reverse flow directions and hence modify the movement of contaminants. The study made it possible to site five boreholes whose positions in the karstic structure were unknown, showing the interest of such an approach for the forecasting of the impact of potential pollution.

Upscaling of Hydraulic Conductivity using the Double Constraint Method

NASA Astrophysics Data System (ADS)

El-Rawy, Mustafa; Zijl, Wouter; Batelaan, Okke

2013-04-01

The mathematics and modeling of flow through porous media is playing an increasingly important role for the groundwater supply, subsurface contaminant remediation and petroleum reservoir engineering. In hydrogeology hydraulic conductivity data are often collected at a scale that is smaller than the grid block dimensions of a groundwater model (e.g. MODFLOW). For instance, hydraulic conductivities determined from the field using slug and packer tests are measured in the order of centimeters to meters, whereas numerical groundwater models require conductivities representative of tens to hundreds of meters of grid cell length. Therefore, there is a need for upscaling to decrease the number of grid blocks in a groundwater flow model. Moreover, models with relatively few grid blocks are simpler to apply, especially when the model has to run many times, as is the case when it is used to assimilate time-dependent data. Since the 1960s different methods have been used to transform a detailed description of the spatial variability of hydraulic conductivity to a coarser description. In this work we will investigate a relatively simple, but instructive approach: the Double Constraint Method (DCM) to identify the coarse-scale conductivities to decrease the number of grid blocks. Its main advantages are robustness and easy implementation, enabling to base computations on any standard flow code with some post processing added. The inversion step of the double constraint method is based on a first forward run with all known fluxes on the boundary and in the wells, followed by a second forward run based on the heads measured on the phreatic surface (i.e. measured in shallow observation wells) and in deeper observation wells. Upscaling, in turn is inverse modeling (DCM) to determine conductivities in coarse-scale grid blocks from conductivities in fine-scale grid blocks. In such a way that the head and flux boundary conditions applied to the fine-scale model are also honored at the coarse-scale. Exemplification will be presented for the Kleine Nete catchment, Belgium. As a result we identified coarse-scale conductivities while decreasing the number of grid blocks with the advantage that a model run costs less computation time and requires less memory space. In addition, ranking of models was investigated.

Impact of high- versus low-dose neuromuscular blocking agent administration on unplanned 30-day readmission rates in retroperitoneal laparoscopic surgery.

PubMed

Boon, Martijn; Martini, Chris; Yang, H Keri; Sen, Shuvayu S; Bevers, Rob; Warlé, Michiel; Aarts, Leon; Niesters, Marieke; Dahan, Albert

2018-01-01

Recent data shows that a neuromuscular block (NMB) induced by administration of high doses of rocuronium improves surgical conditions in certain procedures. However, there are limited data on the effect such practices on postoperative outcomes. We performed a retrospective analysis to compare unplanned 30-day readmissions in patients that received high-dose versus low-dose rocuronium administration during general anesthesia for laparoscopic retroperitoneal surgery. This retrospective cohort study was performed in the Netherlands in an academic hospital where routine high-dose rocuronium NMB has been practiced since July 2015. Charts of patients receiving anesthesia between January 2014 and December 2016 were searched for surgical cases receiving high-dose rocuronium and matched with respect to procedure, age, sex and ASA classification to patients receiving low-dose rocuronium. The primary post-operative outcome was unplanned 30-day readmission rate. There were 130 patients in each cohort. Patients in the high- and low-dose rocuronium cohorts received 217 ± 49 versus 37 ± 5 mg rocuronium, respectively. In the high-dose rocuronium group neuromuscular activity was consistently monitored; matched patients were unreliably monitored. All patients receiving high-dose rocuronium were reversed with sugammadex, while just 33% of matched patients were reversed with sugammadex and 20% with neostigmine; the remaining patients were not reversed. Unplanned 30-day readmission rate was significantly lower in the high-dose compared to the low-dose rocuronium cohort (3.8% vs. 12.7%; p = 0.03; odds ratio = 0.33, 95% C.I. 0.12-0.95). This small retrospective study demonstrates a lower incidence of unplanned readmissions within 30-days following laparoscopic retroperitoneal surgery with high-dose relaxant anesthesia and sugammadex reversal in comparison to low-dose relaxant anesthesia. Further prospective studies are needed in larger samples to corroborate our findings and additionally assess the pharmacoeconomics of high-dose relaxant anesthesia taking into account the benefits (reduced readmissions) and harm (cost of relaxants and reversal agents) of such practice.

Atheroprotective effects of methotrexate on reverse cholesterol transport proteins and foam cell transformation in human THP-1 monocyte/macrophages.

PubMed

Reiss, Allison B; Carsons, Steven E; Anwar, Kamran; Rao, Soumya; Edelman, Sari D; Zhang, Hongwei; Fernandez, Patricia; Cronstein, Bruce N; Chan, Edwin S L

2008-12-01

To determine whether methotrexate (MTX) can overcome the atherogenic effects of cyclooxygenase 2 (COX-2) inhibitors and interferon-gamma (IFNgamma), both of which suppress cholesterol efflux protein and promote foam cell transformation in human THP-1 monocyte/macrophages. Message and protein levels of the reverse cholesterol transport proteins cholesterol 27-hydroxylase and ATP-binding cassette transporter A1 (ABCA1) in THP-1 cells were evaluated by real-time polymerase chain reaction and immunoblot, respectively. Expression was evaluated in cells incubated in the presence or absence of the COX-2 inhibitor NS398 or IFNgamma, with and without MTX. Foam cell transformation of lipid-laden THP-1 macrophages was detected with oil red O staining and light microscopy. MTX increased 27-hydroxylase message and completely blocked NS398-induced down-regulation of 27-hydroxylase (mean +/- SEM 112.8 +/- 13.1% for NS398 plus MTX versus 71.1 +/- 4.3% for NS398 alone; P < 0.01). MTX also negated COX-2 inhibitor-mediated down-regulation of ABCA1. The ability of MTX to reverse inhibitory effects on 27-hydroxylase and ABCA1 was blocked by the adenosine A2A receptor-specific antagonist ZM241385. MTX also prevented NS398 and IFNgamma from increasing transformation of lipid-laden THP-1 macrophages into foam cells. This study provides evidence supporting the notion of an atheroprotective effect of MTX. Through adenosine A2A receptor activation, MTX promotes reverse cholesterol transport and limits foam cell formation in THP-1 macrophages. This is the first reported evidence that any commonly used medication can increase expression of antiatherogenic reverse cholesterol transport proteins and can counteract the effects of COX-2 inhibition. Our results suggest that one mechanism by which MTX protects against cardiovascular disease in rheumatoid arthritis patients is through facilitation of cholesterol outflow from cells of the artery wall.

Preparation of Ceramic-Bonded Carbon Block for Blast Furnace

NASA Astrophysics Data System (ADS)

Li, Yiwei; Li, Yawei; Sang, Shaobai; Chen, Xilai; Zhao, Lei; Li, Yuanbing; Li, Shujing

2014-01-01

Traditional carbon blocks for blast furnaces are mainly produced with electrically calcined anthracite owing to its good hot metal corrosion resistance. However, this kind of material shows low thermal conductivity and does not meet the demands for cooling of the hearth and the bottom of blast furnaces. In this article, a new kind of a high-performance carbon block has been prepared via ceramic-bonded carbon (CBC) technology in a coke bed at 1673 K (1400 °C) using artificial graphite aggregate, alumina, metallic aluminum, and silicon powders as starting materials. The results showed that artificial graphite aggregates were strongly bonded by the three-dimensional network of ceramic phases in carbon blocks. In this case, the good resistance of the CBC blocks against erosion/corrosion by the hot metal is provided by the ceramic matrix and the high thermal conductivity by the graphite aggregates. The microstructure of this carbon block resembles that of CBC composites with a mean pore size of less than 0.1 μm, and up to 90 pct of the porosity shows a pore size <1 μm. Its thermal conductivity is higher than 30 W · m-1 · K-1 [293 K (20 °C)]. Meanwhile, its hot metal corrosion resistance is better than that of traditional carbon blocks.

Static Performance of a Wing-Mounted Thrust Reverser Concept

NASA Technical Reports Server (NTRS)

Asbury, Scott C.; Yetter, Jeffrey A.

1998-01-01

An experimental investigation was conducted in the Jet-Exit Test Facility at NASA Langley Research Center to study the static aerodynamic performance of a wing-mounted thrust reverser concept applicable to subsonic transport aircraft. This innovative engine powered thrust reverser system is designed to utilize wing-mounted flow deflectors to produce aircraft deceleration forces. Testing was conducted using a 7.9%-scale exhaust system model with a fan-to-core bypass ratio of approximately 9.0, a supercritical left-hand wing section attached via a pylon, and wing-mounted flow deflectors attached to the wing section. Geometric variations of key design parameters investigated for the wing-mounted thrust reverser concept included flow deflector angle and chord length, deflector edge fences, and the yaw mount angle of the deflector system (normal to the engine centerline or parallel to the wing trailing edge). All tests were conducted with no external flow and high pressure air was used to simulate core and fan engine exhaust flows. Test results indicate that the wing-mounted thrust reverser concept can achieve overall thrust reverser effectiveness levels competitive with (parallel mount), or better than (normal mount) a conventional cascade thrust reverser system. By removing the thrust reverser system from the nacelle, the wing-mounted concept offers the nacelle designer more options for improving nacelle aero dynamics and propulsion-airframe integration, simplifying nacelle structural designs, reducing nacelle weight, and improving engine maintenance access.

Paving block study : final report.

DOT National Transportation Integrated Search

1971-10-01

The Louisiana Department of Highways has conducted field tests with an experimental revetment consisting of cellular concrete revetment blocks used in conjunction with plastic filter cloth and/or vegetation such as grass or vines. The precast blocks ...

Simultaneous conduction over the fast and slow pathways during induction of atrioventricular nodal reentrant arrhythmia with a rate of less than 100 bpm and infra-His block after radiofrequency ablation of the slow pathway.

PubMed

Amasyalı, Basri; Köktürk, Bülent; Otomo, Kiyoshi; Köse, Sedat

2011-04-01

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common form of paroxysmal regular supraventricular tachycardia in adults. It is typically induced with an anterograde block over the fast pathway (FP) and conduction over the slow pathway (SP), with subsequent retrograde conduction over the FP. Rarely, a simultaneous conduction of a premature atrial complex occurs over the FP and SP to induce AVNRT and is called "one for two phenomenon". We present a 46-year-old woman with atrioventricular nodal rhythm with a rate of 95 beats per minute with distinct electrophysiological characteristics showing simultaneous conduction over the FP and SP during induction of tachycardia and an infra-His block after radiofrequency ablation of the SP.

Stereoselective modulatory actions of oleamide on GABAA receptors and voltage-gated Na+ channels in vitro: a putative endogenous ligand for depressant drug sites in CNS

PubMed Central

Verdon, Bernard; Zheng, Jian; Nicholson, Russell A; Ganelli, C Robin; Lees, George

2000-01-01

cis-9,10-octadecenoamide (‘oleamide') accumulates in CSF on sleep deprivation. It induces sleep in animals (the trans form is inactive) but its cellular actions are poorly characterized. We have used electrophysiology in cultures from embryonic rat cortex and biochemical studies in mouse nerve preparations to address these issues. Twenty μM cis-oleamide (but not trans) reversibly enhanced GABAA currents and depressed the frequency of spontaneous excitatory and inhibitory synaptic activity in cultured networks. cis-oleamide stereoselectively blocked veratridine-induced (but not K+-induced) depolarisation of mouse synaptoneurosomes (IC50, 13.9 μM). The cis isomer stereoselectively blocked veratridine-induced (but not K+-induced) [3H]-GABA release from mouse synaptosomes (IC50, 4.6 μM). At 20 μM cis-oleamide, but not trans, produced a marked inhibition of Na+ channel-dependent rises in intrasynaptosomal Ca2+. The physiological significance of these observations was examined by isolating Na+ spikes in cultured pyramidal neurones. Sixty-four μM cis-oleamide did not significantly alter the amplitude, rate of rise or duration of unitary action potentials (1 Hz). cis-Oleamide stereoselectively suppressed sustained repetitive firing (SRF) in these cells with an EC50 of 4.1 μM suggesting a frequency- or state-dependent block of voltage-gated Na+ channels. Oleamide is a stereoselective modulator of both postsynaptic GABAA receptors and presynaptic or somatic voltage-gated Na+ channels which are crucial for synaptic inhibition and conduction. The modulatory actions are strikingly similar to those displayed by sedative or anticonvulsant barbiturates and a variety of general anaesthetics. Oleamide may represent an endogenous modulator for drug receptors and an important regulator of arousal. PMID:10694234

Abasic Phosphorothioate Oligomers Inhibit HIV-1 Reverse Transcription and Block Virus Transmission across Polarized Ectocervical Organ Cultures

PubMed Central

Fraietta, Joseph A.; Mueller, Yvonne M.; Lozenski, Karissa L.; Ratner, Deena; Boesteanu, Alina C.; Hancock, Aidan S.; Lackman-Smith, Carol; Zentner, Isaac J.; Chaiken, Irwin M.; Chung, Suhman; LeGrice, Stuart F. J.; Snyder, Beth A.; Mankowski, Marie K.; Jones, Natalie M.; Hope, Jennifer L.; Gupta, Phalguni; Anderson, Sharon H.; Wigdahl, Brian

2014-01-01

In the absence of universally available antiretroviral (ARV) drugs or a vaccine against HIV-1, microbicides may offer the most immediate hope for controlling the AIDS pandemic. The most advanced and clinically effective microbicides are based on ARV agents that interfere with the earliest stages of HIV-1 replication. Our objective was to identify and characterize novel ARV-like inhibitors, as well as demonstrate their efficacy at blocking HIV-1 transmission. Abasic phosphorothioate 2′ deoxyribose backbone (PDB) oligomers were evaluated in a variety of mechanistic assays and for their ability to inhibit HIV-1 infection and virus transmission through primary human cervical mucosa. Cellular and biochemical assays were used to elucidate the antiviral mechanisms of action of PDB oligomers against both lab-adapted and primary CCR5- and CXCR4-utilizing HIV-1 strains, including a multidrug-resistant isolate. A polarized cervical organ culture was used to test the ability of PDB compounds to block HIV-1 transmission to primary immune cell populations across ectocervical tissue. The antiviral activity and mechanisms of action of PDB-based compounds were dependent on oligomer size, with smaller molecules preventing reverse transcription and larger oligomers blocking viral entry. Importantly, irrespective of molecular size, PDBs potently inhibited virus infection and transmission within genital tissue samples. Furthermore, the PDB inhibitors exhibited excellent toxicity and stability profiles and were found to be safe for vaginal application in vivo. These results, coupled with the previously reported intrinsic anti-inflammatory properties of PDBs, support further investigations in the development of PDB-based topical microbicides for preventing the global spread of HIV-1. PMID:25224013

Selective control of small versus large diameter axons using infrared laser light (Conference Presentation)

NASA Astrophysics Data System (ADS)

Lothet, Emilie H.; Shaw, Kendrick M.; Horn, Charles C.; Lu, Hui; Wang, Yves T.; Jansen, E. Duco; Chiel, Hillel J.; Jenkins, Michael W.

2016-03-01

Sensory information is conveyed to the central nervous system via small diameter unmyelinated fibers. In general, smaller diameter axons have slower conduction velocities. Selective control of such fibers could create new clinical treatments for chronic pain, nausea in response to chemo-therapeutic agents, or hypertension. Electrical stimulation can control axonal activity, but induced axonal current is proportional to cross-sectional area, so that large diameter fibers are affected first. Physiologically, however, synaptic inputs generally affect small diameter fibers before large diameter fibers (the size principle). A more physiological modality that first affected small diameter fibers could have fewer side effects (e.g., not recruiting motor axons). A novel mathematical analysis of the cable equation demonstrates that the minimum length along the axon for inducing block scales with the square root of axon diameter. This implies that the minimum length along an axon for inhibition will scale as the square root of axon diameter, so that lower radiant exposures of infrared light will selectively affect small diameter, slower conducting fibers before those of large diameter. This prediction was tested in identified neurons from the marine mollusk Aplysia californica. Radiant exposure to block a neuron with a slower conduction velocity (B43) was consistently lower than that needed to block a faster conduction velocity neuron (B3). Furthermore, in the vagus nerve of the musk shrew, lower radiant exposure blocked slow conducting fibers before blocking faster conducting fibers. Infrared light can selectively control smaller diameter fibers, suggesting many novel clinical treatments.

Detection of SYT-SSX mutant transcripts in formalin-fixed paraffin-embedded sarcoma tissues using one-step reverse transcriptase real-time PCR.

PubMed

Norlelawati, A T; Mohd Danial, G; Nora, H; Nadia, O; Zatur Rawihah, K; Nor Zamzila, A; Naznin, M

2016-04-01

Synovial sarcoma (SS) is a rare cancer and accounts for 5-10% of adult soft tissue sarcomas. Making an accurate diagnosis is difficult due to the overlapping histological features of SS with other types of sarcomas and the non-specific immunohistochemistry profile findings. Molecular testing is thus considered necessary to confirm the diagnosis since more than 90% of SS cases carry the transcript of t(X;18)(p11.2;q11.2). The purpose of this study is to diagnose SS at molecular level by testing for t(X;18) fusion-transcript expression through One-step reverse transcriptase real-time Polymerase Chain Reaction (PCR). Formalin-fixed paraffin-embedded tissue blocks of 23 cases of soft tissue sarcomas, which included 5 and 8 cases reported as SS as the primary diagnosis and differential diagnosis respectively, were retrieved from the Department of Pathology, Tengku Ampuan Afzan Hospital, Kuantan, Pahang. RNA was purified from the tissue block sections and then subjected to One-step reverse transcriptase real-time PCR using sequence specific hydrolysis probes for simultaneous detection of either SYT-SSX1 or SYT-SSX2 fusion transcript. Of the 23 cases, 4 cases were found to be positive for SYT-SSX fusion transcript in which 2 were diagnosed as SS whereas in the 2 other cases, SS was the differential diagnosis. Three cases were excluded due to failure of both amplification assays SYT-SSX and control β-2-microglobulin. The remaining 16 cases were negative for the fusion transcript. This study has shown that the application of One-Step reverse transcriptase real time PCR for the detection SYT-SSX transcript is feasible as an aid in confirming the diagnosis of synovial sarcoma.

The BDNF/TrkB signaling pathway is involved in heat hyperalgesia mediated by Cdk5 in rats.

PubMed

Zhang, Hong-Hai; Zhang, Xiao-Qin; Xue, Qing-Sheng; Yan-Luo; Huang, Jin-Lu; Zhang, Su; Shao, Hai-Jun; Lu, Han; Wang, Wen-Yuan; Yu, Bu-Wei

2014-01-01

Cyclin-dependent kinase 5 (Cdk5) has been shown to play an important role in mediating inflammation-induced heat hyperalgesia. However, the underlying mechanism remains unclear. The aim of this study was to determine whether roscovitine, an inhibitor of Cdk5, could reverse the heat hyperalgesia induced by peripheral injection of complete Freund's adjuvant (CFA) via the brain-derived neurotrophic factor (BDNF)-tyrosine kinase B (TrkB) signaling pathway in the dorsal horn of the spinal cord in rats. Heat hyperalgesia induced by peripheral injection of CFA was significantly reversed by roscovitine, TrkB-IgG, and the TrkB inhibitor K252a, respectively. Furthermore, BDNF was significantly increased from 0.5 h to 24 h after CFA injection in the spinal cord dorsal horn. Intrathecal adminstration of the Cdk5 inhibitor roscovitine had no obvious effects on BDNF levels. Increased TrkB protein level was significantly reversed by roscovitine between 0.5 h and 6 h after CFA injection. Cdk5 and TrkB co-immunoprecipitation results suggested Cdk5 mediates the heat hyperalgesia induced by CFA injection by binding with TrkB, and the binding between Cdk5 and TrkB was markedly blocked by intrathecal adminstration of roscovitine. Our data suggested that the BDNF-TrkB signaling pathway was involved in CFA-induced heat hyperalgesia mediated by Cdk5. Roscovitine reversed the heat hyperalgesia induced by peripheral injection of CFA by blocking BDNF/TrkB signaling pathway, suggesting that severing the close crosstalk between Cdk5 and the BDNF/TrkB signaling cascade may present a potential target for anti-inflammatory pain.

Methadone Reverses Analgesic Tolerance Induced by Morphine Pretreatment

PubMed Central

Posa, Luca; Accarie, Alison; Marie, Nicolas

2016-01-01

Background: Opiates such as morphine are the most powerful analgesics, but their protracted use is restrained by the development of tolerance to analgesic effects. Recent works suggest that tolerance to morphine might be due to its inability to promote mu opioid receptor endocytosis, and the co-injection of morphine with a mu opioid receptor internalizing agonist like [D-Ala2,N-Me-Phe4,Gly-ol5]enkephalin reduces tolerance to morphine. So far, no studies have been conducted to evaluate the ability of methadone to reduce morphine tolerance in morphine-pretreated animals, a treatment sequence that could be encountered in opiate rotation protocol. We investigated the ability of methadone (a mu opioid receptor internalizing agonist used in therapy) to reverse morphine tolerance and the associated cellular mechanisms in the periaqueductal gray matter, a region involved in pain control. Methods: We measured analgesic response following a challenge dose of morphine in the hot plate test and investigated regulation of mu opioid receptor (coupling and endocytosis) and some cellular mechanisms involved in tolerance such as adenylate cyclase superactivation and changes in N-methyl-d-aspartate receptor subunits expression and phosphorylation state. Results: A chronic treatment with morphine promoted tolerance to its analgesic effects and was associated with a lack of mu opioid receptor endocytosis, adenylate cyclase overshoot, NR2A and NR2B downregulation, and phosphorylation of NR1. We reported that a methadone treatment in morphine-treated mice reversed morphine tolerance to analgesia by promoting mu opioid receptor endocytosis and blocking cellular mechanisms of tolerance. Conclusions: Our data might lead to rational strategies to tackle opiate tolerance in the frame of opiate rotation. PMID:26390873

Microstructure Refinement and Mechanical Properties of 304 Stainless Steel by Repetitive Thermomechanical Processing

NASA Astrophysics Data System (ADS)

Al-Fadhalah, Khaled; Aleem, Muhammad

2018-04-01

Repetitive thermomechanical processing (TMP) was applied for evaluating the effect of strain-induced α'-martensite transformation and reversion annealing on microstructure refinement and mechanical properties of 304 austenitic stainless steel. The first TMP scheme consisted of four cycles of tensile deformation to strain of 0.4, while the second TMP scheme applied two cycles of tensile straining to 0.6. For both schemes, tensile tests were conducted at 173 K (- 100 °C) followed by 5-minute annealing at 1073 K (800 °C). The volume fraction of α'-martensite in deformed samples increased with increasing cycles, reaching a maximum of 98 vol pct. Examination of annealed microstructure by electron backscattered diffraction indicated that increasing strain and/or number of cycles resulted in stronger reversion to austenite with finer grain size of 1 μm. Yet, increasing strain reduced the formation of Σ3 boundaries. The annealing textures generally show reversion of α'-martensite texture components to the austenite texture of brass and copper orientations. The increase in strain and/or number of cycles resulted in stronger intensity of copper orientation, accompanied by the formation of recrystallization texture components of Goss, cube, and rotated cube. The reduction in grain size with increasing cycles caused an increase in yield strength. It also resulted in an increase in strain hardening rate during deformation due to the increase in the formation of α'-martensite. The increase in strain hardening rate occurred in two consecutive stages, marked as stages II and III. The strain hardening in stage II is due to the formation of α'-martensite from either austenite or ɛ-martensite, while the stage-III strain hardening is attributed to the necessity to break the α'-martensite-banded structure for forming block-type martensite at high strains.

Effect of cardiac resynchronization therapy on beat-to-beat T-wave amplitude variability.

PubMed

Žižek, David; Cvijić, Marta; Tasič, Jerneja; Jan, Matevž; Frljak, Sabina; Zupan, Igor

2012-11-01

T-wave amplitude variability (TAV) is a promising non-invasive predictor of arrhythmic events in patients with dilated cardiomyopathy. We aimed to evaluate the effect of cardiac resynchronization therapy (CRT) on native TAV, its relation with left ventricular (LV) reverse remodelling and the occurrence of ventricular tachyarrhythmias (VTs). In this prospective study, we included 40 heart failure patients with left bundle branch block in sinus rhythm (25 male; 16 with ischaemic aetiology; aged 62.7 ± 9.5 years; New York Heart Association class II-IV). Echocardiographic parameters and TAV were evaluated at baseline and 6 months after implantation of CRT device combined with an implantable cardioverter-defibrillator. T-wave amplitude variability was determined by a 20-min high-resolution electrocardiogram Holter recording during native conduction. After TAV assessment, patients were monitored for 15.7 ± 5.2 months for the occurrence of VTs. Decrease in median TAV [from 40.45 μV (24.75-56.00) to 28.15 μV (20.93-37.95), P = 0.004] was observed after 6 months of CRT. However, decrease of median TAV was only noticed in patients with LV reverse remodelling [46.9 μV (27.5-70.0) to 25.8 μV (20.2-32.4), P < 0.001] and in patients without VTs [40.5 μV (27.5-55.9) to 24.4 μV (17.1-31.5), P < 0.001]. Native median TAV > 35.4 µV after 6 months of CRT had an 83% sensitivity and 93% specificity for predicting the occurrence of VTs. Decrease of TAV after CRT is associated with LV reverse remodelling and indicates a reduction of the intrinsic arrhythmogenic substrate. Median TAV after CRT had a good predicting value for VT occurrence in long-term follow-up.

Comprehensive two-dimensional liquid chromatographic analysis of poloxamers.

PubMed

Malik, Muhammad Imran; Lee, Sanghoon; Chang, Taihyun

2016-04-15

Poloxamers are low molar mass triblock copolymers of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO), having number of applications as non-ionic surfactants. Comprehensive one and two-dimensional liquid chromatographic (LC) analysis of these materials is proposed in this study. The separation of oligomers of both types (PEO and PPO) is demonstrated for several commercial poloxamers. This is accomplished at the critical conditions for one of the block while interaction for the other block. Reversed phase LC at CAP of PEO allowed for oligomeric separation of triblock copolymers with regard to PPO block whereas normal phase LC at CAP of PPO renders oligomeric separation with respect to PEO block. The oligomeric separation with regard to PEO and PPO are coupled online (comprehensive 2D-LC) to reveal two-dimensional contour plots by unconventional 2D IC×IC (interaction chromatography) coupling. The study provides chemical composition mapping of both PEO and PPO, equivalent to combined molar mass and chemical composition mapping for several commercial poloxamers. Copyright © 2016 Elsevier B.V. All rights reserved.

Magnetic hydrogels from alkyne/cobalt carbonyl-functionalized ABA triblock copolymers

DOE PAGES

Jiang, Bingyin; Hom, Wendy L.; Chen, Xianyin; ...

2016-03-09

A series of alkyne-functionalized poly(4-(phenylethynyl)styrene)- block-poly(ethylene oxide)- block-poly(4-(phenylethynyl)styrene) (PPES-b-PEO-b-PPES) ABA triblock copolymers was synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization. PES n[Co 2(CO) 6] x-EO 800-PES n[Co 2(CO) 6] x ABA triblock copolymer/cobalt adducts (10–67 wt % PEO) were subsequently prepared by reaction of the alkyne-functionalized PPES block with Co 2(CO) 8 and their phase behavior was studied by TEM. Heating triblock copolymer/cobalt carbonyl adducts at 120 °C led to cross-linking of the PPES/Co domains and the formation of magnetic cobalt nanoparticles within the PPES/Co domains. Magnetic hydrogels could be prepared by swelling the PEO domains of the cross-linkedmore » materials with water. Furthermore, swelling tests, rheological studies and actuation tests demonstrated that the water capacity and modulus of the hydrogels were dependent upon the composition of the block copolymer precursors.« less

Discovery, development, and clinical application of sugammadex sodium, a selective relaxant binding agent

PubMed Central

Welliver, Mark; McDonough, John; Kalynych, Nicholas; Redfern, Robert

2008-01-01

Neuromuscular blockade, induced by neuromuscular blocking agents, has allowed prescribed immobility, improved surgical exposure, optimal airway management conditions, and facilitated mechanical ventilation. However, termination of the effects of neuromuscular blocking agents has, until now, remained limited. A novel cyclodextrin encapsulation process offers improved termination of the paralytic effects of aminosteroidal non-depolarizing neuromuscular blocking agents. Sugammadex sodium is the first in a new class of drug called selective relaxant binding agents. Currently, in clinical trials, sugammadex, a modified gamma cyclodextrin, has shown consistent and rapid termination of neuromuscular blockade with few side effects. The pharmacology of cyclodextrins in general and sugammadex in particular, together with the results of current clinical research are reviewed. The ability of sugammadex to terminate the action of neuromuscular blocking agents by direct encapsulation is compared to the indirect competitive antagonism of their effects by cholinesterase inhibitors. Also discussed are the clinical implications that extend beyond fast, effective reversal, including numerous potential perioperative benefits. PMID:19920893

Inhibition of mechanotransducer currents in crayfish sensory neuron by CGS 9343B, a calmodulin antagonist.

PubMed

Lin, J H; Rydqvist, B

2000-05-26

The effects of CGS 9343B (zaldaride maleate), a calmodulin antagonist, on mechanosensitive channels were examined in crayfish slowly adapting sensory neurons using the two-electrode voltage clamp technique. In addition to its inhibition of voltage-gated Na(+) and K(+) currents, CGS 9343B (<30 microM) blocked reversibly the receptor current in a dose-dependent and voltage-dependent manner with a dissociation constant (K(d)) of 26.8 microM. The time course of the block was 265 s. Within the extension range of 3-30%, the reduction in receptor current was stimulus-independent and the gating mechanisms were not affected. Extracellular Ca(2+) was not necessary for its blocking effects. No changes in passive muscle tension were observed in the presence of 20 microM CGS 9343B. These results suggest that CGS 9343B, as a calmodulin antagonist, can also block mechanosensitive channels, possibly by being incorporated into the lipid membrane and/or interacting with the channel protein.

Ultra-Fast RAFT-HDA Click Conjugation: An Efficient Route to High Molecular Weight Block Copolymers.

PubMed

Inglis, Andrew J; Stenzel, Martina H; Barner-Kowollik, Christopher

2009-11-02

The use of the reversible addition fragmentation chain transfer-hetero Diels-Alder (RAFT-HDA) click reaction for the modular construction of block copolymers is extended to the generation of high molecular weight materials. Cyclopentadienyl end-functionalized polystyrene (PS-Cp) prepared via both atom transfer radical polymerization (ATRP) and the RAFT process are conjugated to poly(isobornyl acrylate) (PiBoA) (also prepared via RAFT polymerization) to achieve well-defined block copolymers with molecular weights ranging from 34 000 to over 100 000 g · mol(-1) and with small polydispersities (PDI < 1.2). The conjugation reactions proceeded in a very rapid fashion (less than 10 min in the majority of cases) under ambient conditions of temperature and atmosphere. The present study demonstrates-for the first time-that RAFT-HDA click chemistry can provide access to high molecular weight block copolymers in a simple and straight-forward fashion. Copyright © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Engineering multifunctional protein nanoparticles by in vitro disassembling and reassembling of heterologous building blocks

NASA Astrophysics Data System (ADS)

Unzueta, Ugutz; Serna, Naroa; Sánchez-García, Laura; Roldán, Mónica; Sánchez-Chardi, Alejandro; Mangues, Ramón; Villaverde, Antonio; Vázquez, Esther

2017-12-01

The engineering of protein self-assembling at the nanoscale allows the generation of functional and biocompatible materials, which can be produced by easy biological fabrication. The combination of cationic and histidine-rich stretches in fusion proteins promotes oligomerization as stable protein-only regular nanoparticles that are composed by a moderate number of building blocks. Among other applications, these materials are highly appealing as tools in targeted drug delivery once empowered with peptidic ligands of cell surface receptors. In this context, we have dissected here this simple technological platform regarding the controlled disassembling and reassembling of the composing building blocks. By applying high salt and imidazole in combination, nanoparticles are disassembled in a process that is fully reversible upon removal of the disrupting agents. By taking this approach, we accomplish here the in vitro generation of hybrid nanoparticles formed by heterologous building blocks. This fact demonstrates the capability to generate multifunctional and/or multiparatopic or multispecific materials usable in nanomedical applications.

A Dynamic Analysis of the Medium Tank Battalion. Volume I

DTIC Science & Technology

1978-06-01

best available copy. W. KEY WORDS (Cortinue an reverse oIde If necessary And Identifty block number) CONSTRUCTION; PLANNING; MANAGEMENT; MODELS...unit, with 64K, 8-bit bytes, (2) Dual-disk drive, 2 Discs at 262K, 8-bit bytes, (3) Cathode Ray Tube Console and Keyboard, (4) High- speed printer, (5

Large Enhancement of the Sagnac Effect Based on Nonlinearly Induced Nonreciprocity.

DTIC Science & Technology

1983-05-30

Og4 ,, % 20. ABSTRACT (Continue on reverse side It ne c,&aty and Identify by block number) LL On Back -°. La . -k. DD 1JAN73 1473 EDITION OF ’NOV6S...be published. 8. L. A. Hackel, R. P. Hackel, and S. Ezekiel, Metrologia 13, 141 (1977). Ř. .4

Projectile Impact Effects on Aircraft Wire Harnesses

DTIC Science & Technology

1986-01-08

circuits Aircraft wire harnesses Modified ETFE Projectile damage and fires 19 ABSTRACT (Continue on reverse if necessary and identit) by block number...Tile Firifinr~ari~ne An overview of tile test fiririý raný,e is shown in Figure b. In tile for-eyrouria is tre rifle, witzh stock removed, utor iuyo e

Fire Protection of Large Air Force Hangars

DTIC Science & Technology

1975-10-01

Aqueous Film - Forming Foam ( AFFF ) in an environment...determining further the effectiveness of 3-percent aqueous film forming foam ( AFFF ); b) determining the effectiveness of AFFF systems at high ceiling...Id SUPPLEMENTARY NOTES 19. KEY WORDS fCont/nu» on reverse side If necessary and Identify by block number) Aqueous Film Forming Foam

Late Triassic paleomagnetic result from the Baoshan Terrane, West Yunnan of China: Implication for orientation of the East Paleotethys suture zone and timing of the Sibumasu-Indochina collision

NASA Astrophysics Data System (ADS)

Zhao, Jie; Huang, Baochun; Yan, Yonggang; Zhang, Donghai

2015-11-01

In order to better understand the paleogeographic position of the Baoshan Terrane in the northernmost part of the Sibumasu Block during formation of the Pangea supercontinent, a paleomagnetic study has been conducted on Late Triassic basaltic lavas from the southern part of the Baoshan Terrane in the West Yunnan region of Southwest China. Following detailed rock magnetic investigations and progressive thermal demagnetization, stable characteristic remanent magnetizations (ChRMs) were successfully isolated from Late Triassic Niuhetang lava flows. The ChRMs are of dual polarity and pass fold and reversal tests with magnetic carriers dominated by magnetite and subordinate oxidation-induced hematite; we thus interpret them as a primary remanence. This new paleomagnetic result indicates that the Baoshan Terrane was located at low paleolatitudes of ∼15°N in the Northern Hemisphere during Late Triassic times. Together with available paleomagnetic data from the Baoshan Terrane and surrounding areas, a wider paleomagnetic comparison supports the view that the East Paleotethys Ocean separated the Sibumasu and Indochina blocks and closed no later than Late Triassic times. We argue that the currently approximately north-to-south directed Changning-Menglian suture zone is very likely to have been oriented nearly east-to-west at the time of the Sibumasu-Indochina collision.

Opiate-induced seizures: a study of mu and delta specific mechanisms.

PubMed

Snead, O C

1986-08-01

Two groups of experiments were conducted to determine if morphine- and enkephalin-induced seizures are specifically mediated by the mu and delta receptor, respectively. In the first experiments, designed to assess the ontogeny of mu- or delta-seizures, rats from 6 h to 85 days of age received implanted cortical and depth electrodes as well as an indwelling cannula in the lateral ventricle. Various amounts of the mu-receptor agonists, morphine and morphiceptin, and the delta agonists, D-Ala2-D-Leu5-enkephalin (DADL) and Tyr-D-Ser-Gly-Phe-Leu-Thr (DSLET), were then administered intracerebroventricularly (icv) with continuous EEG monitoring. The second experiments entailed use of the nonspecific opiate antagonist, naloxone, as well as the specific delta antagonist, ICI 154,129, against seizures induced by icv-administered morphine, morphiceptin, DADL, or DSLET. Both morphine and morphiceptin produced electrical seizure activity in rats as young as 5 days after birth. The drugs produced similar seizure activity in terms of electrical morphology, observed behavior, ontogeny, threshold dose, and reversibility with small doses of naloxone. In the pharmacologic experiments, icv naloxone blocked all opiate-induced seizures. ICI 154,129 blocked DSLET seizure, had little effect on enkephalin or DADL seizures, and no effect on morphine or morphiceptin seizures. These data indicate that DSLET seizures are delta-specific but that all other opiate-induced seizures studied may involve multiple opiate receptor-mediated mechanisms.

Regulation of adhesion and growth of fibrosarcoma cells by NF-kappa B RelA involves transforming growth factor beta.

PubMed Central

Perez, J R; Higgins-Sochaski, K A; Maltese, J Y; Narayanan, R

1994-01-01

The NF-kappa B transcription factor is a pleiotropic activator that participates in the induction of a wide variety of cellular genes. Antisense oligomer inhibition of the RelA subunit of NF-kappa B results in a block of cellular adhesion and inhibition of tumor cell growth. Investigation of the molecular basis for these effects showed that in vitro inhibition of the growth of transformed fibroblasts by relA antisense oligonucleotides can be reversed by the parental-cell-conditioned medium. Cytokine profile analysis of these cells treated with relA antisense oligonucleotides revealed inhibition of transforming growth factor beta 1 (TGF-beta 1 to the transformed fibroblasts reversed the inhibitory effects of relA antisense oligomers on soft agar colony formation and cell adhesion to the substratum. Direct inhibition of TGF-beta 1 expression by antisense phosphorothioates to TGF-beta 1 mimicked the in vitro effects of blocking cell adhesion that are elicited by antisense relA oligomers. These results may explain the in vitro effects of relA antisense oligomers on fibrosarcoma cell growth and adhesion. Images PMID:8035811

The role of sodium pump in the inhibition of smooth muscle responsiveness to agonists during potassium restoration

PubMed Central

Bose, D.; Innes, I. R.

1973-01-01

1. Isometric contractions of cat splenic capsular smooth muscle in response to noradrenaline and histamine were recorded. 2. Removal of potassium from the bathing medium did not change the resting tension or the responsiveness to noradrenaline. Restoration of potassium inhibited responses to noradrenaline or histamine only if the muscles were stimulated with an agonist while in the K-free medium. 3. This inhibition of responses to the agonists due to potassium was reversed rapidly by removing the ion or reversed slowly by prolonged exposure to the ion. The inhibition was also blocked by procedures or agents which block the sodium pump (ouabain, substitution of NaCl by LiCl), inhibit active processes (low ambient temperature) or prevent intracellular accumulation of sodium (substitution of choline for sodium). 4. It is proposed that under special circumstances such as when there is an increase in internal sodium concentration, the sodium pump is probably electrogenic and causes relaxation when activated by external potassium. In the normal muscle the pump is probably electrically neutral. PMID:4777707

Nanocluster building blocks of artificial square spin ice: Stray-field studies of thermal dynamics

NASA Astrophysics Data System (ADS)

Pohlit, Merlin; Porrati, Fabrizio; Huth, Michael; Ohno, Yuzo; Ohno, Hideo; Müller, Jens

2015-05-01

We present measurements of the thermal dynamics of a Co-based single building block of an artificial square spin ice fabricated by focused electron-beam-induced deposition. We employ micro-Hall magnetometry, an ultra-sensitive tool to study the stray field emanating from magnetic nanostructures, as a new technique to access the dynamical properties during the magnetization reversal of the spin-ice nanocluster. The obtained hysteresis loop exhibits distinct steps, displaying a reduction of their "coercive field" with increasing temperature. Therefore, thermally unstable states could be repetitively prepared by relatively simple temperature and field protocols allowing one to investigate the statistics of their switching behavior within experimentally accessible timescales. For a selected switching event, we find a strong reduction of the so-prepared states' "survival time" with increasing temperature and magnetic field. Besides the possibility to control the lifetime of selected switching events at will, we find evidence for a more complex behavior caused by the special spin ice arrangement of the macrospins, i.e., that the magnetic reversal statistically follows distinct "paths" most likely driven by thermal perturbation.

Micronuclei induced by reverse transcriptase inhibitors in mononucleated and binucleated cells as assessed by the cytokinesis-block micronucleus assay

PubMed Central

2010-01-01

This study evaluated the clastogenic and/or aneugenic potential of three nucleoside reverse transcriptase inhibitors (zidovudine - AZT, lamivudine - 3TC and stavudine - d4T) using the cytokinesis-block micronucleus (CBMN) assay in human lymphocyte cultures. All three inhibitors produced a positive response when tested in binucleated cells. The genotoxicity of AZT and 3TC was restricted to binucleated cells since there was no significant increase in the frequency of micronuclei in mononucleated cells. This finding indicated that AZT and 3TC caused chromosomal breakage and that their genotoxicity was related to a clastogenic action. In addition to the positive response observed with d4T in binucleated cells, this drug also increased the frequency of micronuclei in mononucleated cells, indicating clastogenic and aneugenic actions. Since the structural differences between AZT and 3TC and AZT and d4T involve the 3' position in the 2'-deoxyribonucleoside and in an unsaturated 2',3',dideoxyribose, respectively, we suggest that an unsaturated 2', 3', dideoxyribose is responsible for the clastogenic and aneugenic actions of d4T. PMID:21637587

Preliminary interpretation of industry two-dimensional seismic data from Susitna Basin, south-central Alaska

USGS Publications Warehouse

Lewis, Kristen A.; Potter, Christopher J.; Shah, Anjana K.; Stanley, Richard G.; Haeussler, Peter J.; Saltus, Richard W.

2015-07-30

The eastern seismic lines show evidence of numerous short-wavelength antiforms that appear to correspond to a series of northeast-trending lineations observed in aeromagnetic data, which have been interpreted as being due to folding of Paleogene volcanic strata. The eastern side of the basin is also cut by a number of reverse faults and thrust faults, the majority of which strike north-south. The western side of the Susitna Basin is cut by a series of regional reverse faults and is characterized by synformal structures in two fault blocks between the Kahiltna River and Skwentna faults. These synforms are progressively deeper to the west in the footwalls of the east-vergent Skwentna and northeast-vergent Beluga Mountain reverse faults. Although the seismic data are limited to the south, we interpret a potential regional south-southeast-directed reverse fault striking east-northeast on the east side of the basin that may cross the entire southern portion of the basin.

Serotonin, atherosclerosis, and collateral vessel spasm

NASA Technical Reports Server (NTRS)

Hollenberg, N.

1988-01-01

Studies on animal models demonstrate that platelet products contribute to vascular spasm in ischemic syndromes and that this is reversible with administration of ketanserin and thromboxane synthesis inhibitors. Laboratory animals (dogs, rabbits, and rats) that had femoral artery ligations exhibited supersensitivity to serotonin within days in their collateral blood vessels. This supersensitivity lasted at least 6 months. The response to serotonin was reversed by ketanserin, but not by 5HT-1 antagonists. Supersensitivity does not extend to norepinephrine, and alpha blockers do not influence the response to serotonin. It appears that platelet activation by endothelial injury contributes to ischemia through blood vessel occlusion and vascular spasm. When platelet activation occurs in vivo, blood vessel occlusion and vascular spasm are reversible in part by using ketanserin or agents that block thromboxane synthesis or its action. Combining both classes of agents reverses spasm completely. These findings support existing evidence that platelet products contribute to vascular disease, and provide an approach to improved management with currently available pharmacologic agents.

Regulation of exocytotic fusion by cell inflation.

PubMed Central

Solsona, C; Innocenti, B; Fernández, J M

1998-01-01

We have inflated patch-clamped mast cells by 3.8 +/- 1.6 times their volume by applying a hydrostatic pressure of 5-15 cm H2O to the interior of the patch pipette. Inflation did not cause changes in the cell membrane conductance and caused only a small reversible change in the cell membrane capacitance (36 +/- 5 fF/cm H2O). The specific cell membrane capacitance of inflated cells was found to be 0.5 microF/cm2. High-resolution capacitance recordings showed that inflation reduced the frequency of exocytotic fusion events by approximately 70-fold, with the remaining fusion events showing an unusual time course. Shortly after the pressure was returned to 0 cm H2O, mast cells regained their normal size and appearance and degranulated completely, even after remaining inflated for up to 60 min. We interpret these observations as an indication that inflated mast cells reversibly disassemble the structures that regulate exocytotic fusion. Upon returning to its normal size, the cell cytosol reassembles the fusion pore scaffolds and allows exocytosis to proceed, suggesting that exocytotic fusion does not require soluble proteins. Reassembly of the fusion pore can be prevented by inflating the cells with solutions containing the protease pronase, which completely blocked exocytosis. We also interpret these results as evidence that the activity of the fusion pore is sensitive to the tension of the plasma membrane. PMID:9533718

Effect of yohimbine on detomidine induced changes in behavior, cardiac and blood parameters in the horse.

PubMed

DiMaio Knych, Heather K; Covarrubias, Vanessa; Steffey, Eugene P

2012-11-01

To describe selected pharmacodynamic effects of detomidine and yohimbine when administered alone and in sequence. Randomized crossover design. Nine healthy adult horses aged 9 ± 4 years and weighing 561 ± 56 kg. Three dose regimens were employed in the current study. 1) 0.03 mg kg(-1) detomidine IV, 2) 0.2 mg kg(-1) yohimbine IV and 3) 0.03 mg kg(-1) detomidine IV followed 15 minutes later by 0.2 mg kg(-1) yohimbine IV. Each horse received all three treatments with a minimum of 1 week between treatments. Blood samples were obtained and plasma analyzed for detomidine and yohimbine concentrations by liquid chromatography-mass spectrometry. Behavioral effects, heart rate and rhythm, glucose, packed cell volume and plasma proteins were monitored. Yohimbine rapidly reversed the sedative effects of detomidine in the horse. Additionally, yohimbine effectively returned heart rate and the percent of atrio-ventricular conduction disturbances to pre-detomidine values when administered 15 minutes post-detomidine administration. Plasma glucose was significantly increased following detomidine administration. The detomidine induced hyperglycemia was effectively reduced by yohimbine administration. Effects on packed cell volume and plasma proteins were variable. Intravenous administration of yohimbine effectively reversed detomidine induced sedation, bradycardia, atrio-ventricular heart block and hyperglycemia. © 2012 The Authors. Veterinary Anaesthesia and Analgesia. © 2012 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists.

Forward- and reverse-bias tunneling effects in n/+/p silicon solar cells

NASA Technical Reports Server (NTRS)

Garlick, G. F. J.; Kachare, A. H.

1980-01-01

Excess currents due to field-assisted tunneling in both forward and reverse bias directions have been observed in n(+)-p silicon solar cells. These currents arise from the effect of conducting paths produced in the depletion layer by n(+) diffusion and cell processing. Forward-bias data indicate a small potential barrier with height of 0.04 eV at the n(+) end of conducting paths. Under reverse bias, excess tunneling currents involve a potential barrier at the p end of the conducting paths, the longer paths being associated with smaller barrier heights and dominating at the lower temperatures. Low-reverse-bias data give energy levels of 0.11 eV for lower temperatures (253-293 K) and 0.35 eV for higher temperatures (293-380 K). A model is suggested to explain the results.

Heparan sulfate storage in the cardiac conduction system triggers atrioventricular block.

PubMed

Kato, Rie; Miyahara, Hiroaki; Kawano, Tatsuya; Matsuzuka, Atsuko; Noda, Kimiko; Izumi, Tatsuro

2017-05-01

To elucidate the novel biological functions of heparan sulfate (HS) by clinic-pathologically studying a patient with paroxysmal atrioventricular (AV) block. A long-surviving male patient with Sanfilippo syndrome type A presented with paroxysmal AV block at age 33years. He then survived another 2.5years after the onset of paroxysmal AV block and pacemaker implantation. His cardiac histopathological examination at autopsy showed HS storage in the cardiac conduction system (CCS), especially in the atrioventricular node (AVN)-His bundle branches. HS storage in the CCS might trigger AV block, arising from below the AVN-His bundle branches. This is the first description to indicate that HS might be an essential constituent of life-long CCS plasticity and that its storage in the CCS results in AV block. Copyright © 2017 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

Adolescent Boys' and Girls' Block Constructions Differ in Structural Balance: A Block-Building Characteristic Related to Math Achievement

ERIC Educational Resources Information Center

Casey, Beth M.; Pezaris, Elizabeth E.; Bassi, Julie

2012-01-01

Two studies were conducted on block building in adolescents, assessing middle school (Study 1) and high school students (Study 2). Students were asked to build something interesting with blocks. In both samples, the same pattern of gender differences were found; boys built taller structures than girls, and balanced a larger number of blocks on a…

Modeling the response of small myelinated axons in a compound nerve to kilohertz frequency signals

NASA Astrophysics Data System (ADS)

Pelot, N. A.; Behrend, C. E.; Grill, W. M.

2017-08-01

Objective. There is growing interest in electrical neuromodulation of peripheral nerves, particularly autonomic nerves, to treat various diseases. Electrical signals in the kilohertz frequency (KHF) range can produce different responses, including conduction block. For example, EnteroMedics’ vBloc® therapy for obesity delivers 5 kHz stimulation to block the abdominal vagus nerves, but the mechanisms of action are unclear. Approach. We developed a two-part computational model, coupling a 3D finite element model of a cuff electrode around the human abdominal vagus nerve with biophysically-realistic electrical circuit equivalent (cable) model axons (1, 2, and 5.7 µm in diameter). We developed an automated algorithm to classify conduction responses as subthreshold (transmission), KHF-evoked activity (excitation), or block. We quantified neural responses across kilohertz frequencies (5-20 kHz), amplitudes (1-8 mA), and electrode designs. Main results. We found heterogeneous conduction responses across the modeled nerve trunk, both for a given parameter set and across parameter sets, although most suprathreshold responses were excitation, rather than block. The firing patterns were irregular near transmission and block boundaries, but otherwise regular, and mean firing rates varied with electrode-fibre distance. Further, we identified excitation responses at amplitudes above block threshold, termed ‘re-excitation’, arising from action potentials initiated at virtual cathodes. Excitation and block thresholds decreased with smaller electrode-fibre distances, larger fibre diameters, and lower kilohertz frequencies. A point source model predicted a larger fraction of blocked fibres and greater change of threshold with distance as compared to the realistic cuff and nerve model. Significance. Our findings of widespread asynchronous KHF-evoked activity suggest that conduction block in the abdominal vagus nerves is unlikely with current clinical parameters. Our results indicate that compound neural or downstream muscle force recordings may be unreliable as quantitative measures of neural activity for in vivo studies or as biomarkers in closed-loop clinical devices.

Modeling the response of small myelinated axons in a compound nerve to kilohertz frequency signals.

PubMed

Pelot, N A; Behrend, C E; Grill, W M

2017-08-01

There is growing interest in electrical neuromodulation of peripheral nerves, particularly autonomic nerves, to treat various diseases. Electrical signals in the kilohertz frequency (KHF) range can produce different responses, including conduction block. For example, EnteroMedics' vBloc ® therapy for obesity delivers 5 kHz stimulation to block the abdominal vagus nerves, but the mechanisms of action are unclear. We developed a two-part computational model, coupling a 3D finite element model of a cuff electrode around the human abdominal vagus nerve with biophysically-realistic electrical circuit equivalent (cable) model axons (1, 2, and 5.7 µm in diameter). We developed an automated algorithm to classify conduction responses as subthreshold (transmission), KHF-evoked activity (excitation), or block. We quantified neural responses across kilohertz frequencies (5-20 kHz), amplitudes (1-8 mA), and electrode designs. We found heterogeneous conduction responses across the modeled nerve trunk, both for a given parameter set and across parameter sets, although most suprathreshold responses were excitation, rather than block. The firing patterns were irregular near transmission and block boundaries, but otherwise regular, and mean firing rates varied with electrode-fibre distance. Further, we identified excitation responses at amplitudes above block threshold, termed 're-excitation', arising from action potentials initiated at virtual cathodes. Excitation and block thresholds decreased with smaller electrode-fibre distances, larger fibre diameters, and lower kilohertz frequencies. A point source model predicted a larger fraction of blocked fibres and greater change of threshold with distance as compared to the realistic cuff and nerve model. Our findings of widespread asynchronous KHF-evoked activity suggest that conduction block in the abdominal vagus nerves is unlikely with current clinical parameters. Our results indicate that compound neural or downstream muscle force recordings may be unreliable as quantitative measures of neural activity for in vivo studies or as biomarkers in closed-loop clinical devices.

Reversible CSF cyst related to a functioning ventriculo-peritoneal shunt.

PubMed

Vajramani, G V; Fugleholm, K

2005-11-01

Although the occurrence of CSF oedema and cyst has been described in presence of a blocked ventriculoperitoneal shunt, especially distal end block, its occurrence in presence of a well functioning shunt has not been described so far. We report a case where a 51-year old lady developed an insidious onset and gradually progressive CSF cyst without any clinical or radiological feature of shunt block over a period of about 2 years. The changes started about 6 months after a course of radiation therapy for an extensive residual supra and infratentorial meningioma. Following surgery, where the cyst was punctured and a new ventricular catheter was inserted, despite well functioning upper and lower end, the cyst gradually disappeared. We review the literature and hypothesize that the radiation-induced changes were responsible for initiation and progression of the cyst.

The sometimes competing retrieval and Van Hamme & Wasserman models predict the selective role of within-compound associations in retrospective revaluation.

PubMed

Witnauer, James; Rhodes, L Jack; Kysor, Sarah; Narasiwodeyar, Sanjay

2017-11-21

The correlation between blocking and within-compound memory is stronger when compound training occurs before elemental training (i.e., backward blocking) than when the phases are reversed (i.e., forward blocking; Melchers et al., 2004, 2006). This trial order effect is often interpreted as problematic for performance-focused models that assume a critical role for within-compound associations in both retrospective revaluation and traditional cue competition. The present manuscript revisits this issue using a computational modeling approach. The fit of sometimes competing retrieval (SOCR; Stout & Miller, 2007) was compared to the fit of an acquisition-focused model of retrospective revaluation and cue competition. These simulations reveal that SOCR explains this trial order effect in some situations based on its use of local error reduction. Published by Elsevier B.V.

Perceptions of Teachers in South Florida Toward Block Scheduling.

ERIC Educational Resources Information Center

Hamdy, Mona; Urich, Ted

1998-01-01

A study was conducted at two metropolitan South Florida high schools to determine perceptions of 100 teachers concerning block scheduling. Teachers felt that the 4 X 4 block schedule contained too many time gaps for teaching foreign languages, English, and math. Teachers believed block schedules benefitted advanced students more than others and…

Abnormal Q waves in right sided chest leads provoked by onset of right bundle-branch block in patients with anteroseptal infarction.

PubMed Central

Rosenbaum, M B; Girotti, L A; Lázzari, J O; Halpern, M S; Elizari, M V

1982-01-01

In five cases of anteroseptal myocardial infarction complicated by intermittent right bundle-branch block, the onset of right bundle-branch block provoked the appearance of abnormal Q waves in leads V1 and V2, whereas a small initial R wave was present in the same leads during normal conduction. The intermittency of the conduction disturbance indicated that the Q waves were "right bundle-branch block dependent". It was also apparent that right bundle-branch block shifted the electrical location of the infarct towards the right, and made it look much larger. Right bundle-branch block dependent Q waves may arise during the acute stage of an anterior infarct suggesting, fallaciously, that an acute extension has occurred, or during the chronic stage, leading to the erroneous supposition that a new infarct had developed. The abnormal Q waves anteroseptal infarction complicated by fixed right bundle-branch block, though obviously related to the infarct, may be dependent on the right bundle-branch block. PMID:7059400

Unsteady RANS/DES analysis of flow around helicopter rotor blades at forword flight conditions

NASA Astrophysics Data System (ADS)

Zhang, Zhenyu; Qian, Yaoru

2018-05-01

In this paper, the complex flows around forward-flying helicopter blades are numerically investigated. Both the Reynolds-averaged Navier-Stokes (RANS) and the Detached Eddy Simulation (DES) methods are used for the analysis of characteristics like local dynamic flow separation, effects of radial sweeping and reversed flow. The flow was solved by a highly efficient finite volume solver with multi-block structured grids. Focusing upon the complexity of the advance ratio effects, above properties are fully recognized. The current results showed significant agreements between both RANS and DES methods at phases with attached flow phases. Detailed information of separating flow near the withdrawal phases are given by DES results. The flow analysis of these blades under reversed flow reveals a significant interaction between the reversed flow and the span-wise sweeping.

Bradycardia in a Pediatric Heart Transplant Recipient: Is It the Sugammadex?

PubMed

King, Adele; Naguib, Aymen; Tobias, Joseph D

2017-01-01

Sugammadex is a novel pharmacologic agent that is used to selectively reverse the effects of the neuromuscular blocking agents rocuronium and vecuronium. Various advantages have been reported when comparing its reversal of neuromuscular blockade to that achieved with acetylcholinesterase inhibitors (neostigmine). In heart transplant recipients, bradycardia may occur following the administration of acetylcholinesterase inhibitors, due to the denervation of the heart. Theoretically, the combination of rocuronium and sugammadex could be advantageous in this clinical scenario to avoid the potential bradycardia resulting from neostigmine administration. We present a 10-year-old male who developed profound bradycardia immediately following the administration of intravenous sugammadex. The options for reversal of neuromuscular blockade in heart transplant recipients is discussed, previous reports of bradycardia following sugammadex are presented, and the role of sugammadex in the bradycardia in our patient is reviewed.

Protocol vulnerability detection based on network traffic analysis and binary reverse engineering.

PubMed

Wen, Shameng; Meng, Qingkun; Feng, Chao; Tang, Chaojing

2017-01-01

Network protocol vulnerability detection plays an important role in many domains, including protocol security analysis, application security, and network intrusion detection. In this study, by analyzing the general fuzzing method of network protocols, we propose a novel approach that combines network traffic analysis with the binary reverse engineering method. For network traffic analysis, the block-based protocol description language is introduced to construct test scripts, while the binary reverse engineering method employs the genetic algorithm with a fitness function designed to focus on code coverage. This combination leads to a substantial improvement in fuzz testing for network protocols. We build a prototype system and use it to test several real-world network protocol implementations. The experimental results show that the proposed approach detects vulnerabilities more efficiently and effectively than general fuzzing methods such as SPIKE.

Chromosome movement in lysed mitotic cells is inhibited by vanadate

PubMed Central

1978-01-01

Mitotic PtK1 cells, lysed at anaphase into a carbowax 20 M Brij 58 solution, continue to move chromosomes toward the spindle poles and to move the spindle poles apart at 50% in vivo rates for 10 min. Chromosome movements can be blocked by adding metabolic inhibitors to the lysis medium and inhibition of movement can be reversed by adding ATP to the medium. Vanadate at micromolar levels reversibly inhibits dynein ATPase activity and movement of demembranated flagella and cilia. It does not affect glycerinated myofibril contraction or myosin ATPase activty at less than millimolar concentrations. Vanadate at 10-- 100 micron reversibly inhibits anaphase movement of chromosomes and spindle elongation. After lysis in vanadate, spindles lose their fusiform appearance and become more barrel shaped. In vitro microtubule polymerization is insensitive to vanadate. PMID:152767

Interservice Procedures for Instructional Systems Development. Phase 4 and 5. Implement and Control

DTIC Science & Technology

1975-08-01

FIGUREIZ.2: Flowchart ot Block]Z.1: IMPLEMENT INSTRUCTIONAL MANAGEMENT PLAN BLOCK IV.2: CONDUCT INSTRUCTION LEA Oa.lNUt kaP INSTRUCTIONAL INIIANAI EL...DOCUMENTATION 2.1 [ BTAIN REQUIRED _ _ I 2.J2 CONDUCT INSTRUCTION 1 1 AND DOCUMENT OBSERVATIONS 2.3 ACTIVITIES 2.4 I BLOCK FIGURE ]V.3: Flowchart of...not have the entry skills. The entry skills determi- nation is important to know whether to place the students at the beginn - ing or provide

Involvement of α₂-adrenoceptors, imidazoline, and endothelin-A receptors in the effect of agmatine on morphine and oxycodone-induced hypothermia in mice.

PubMed

Bhalla, Shaifali; Andurkar, Shridhar V; Gulati, Anil

2013-10-01

Potentiation of opioid analgesia by endothelin-A (ET(A)) receptor antagonist, BMS182874, and imidazoline receptor/α₂-adrenoceptor agonists such as clonidine and agmatine are well known. It is also known that agmatine blocks morphine hyperthermia in rats. However, the effect of agmatine on morphine or oxycodone hypothermia in mice is unknown. The present study was carried out to study the role of α₂-adrenoceptors, imidazoline, and ET(A) receptors in morphine and oxycodone hypothermia in mice. Body temperature was determined over 6 h in male Swiss Webster mice treated with morphine, oxycodone, agmatine, and combination of agmatine with morphine or oxycodone. Yohimbine, idazoxan, and BMS182874 were used to determine involvement of α₂-adrenoceptors, imidazoline, and ET(A) receptors, respectively. Morphine and oxycodone produced significant hypothermia that was not affected by α₂-adrenoceptor antagonist yohimbine, imidazoline receptor/α₂ adrenoceptor antagonist idazoxan, or ET(A) receptor antagonist, BMS182874. Agmatine did not produce hypothermia; however, it blocked oxycodone but not morphine-induced hypothermia. Agmatine-induced blockade of oxycodone hypothermia was inhibited by idazoxan and yohimbine. The blockade by idazoxan was more pronounced compared with yohimbine. Combined administration of BMS182874 and agmatine did not produce changes in body temperature in mice. However, when BMS182874 was administered along with agmatine and oxycodone, it blocked agmatine-induced reversal of oxycodone hypothermia. This is the first report demonstrating that agmatine does not affect morphine hypothermia in mice, but reverses oxycodone hypothermia. Imidazoline receptors and α₂-adrenoceptors are involved in agmatine-induced reversal of oxycodone hypothermia. Our findings also suggest that ET(A) receptors may be involved in blockade of oxycodone hypothermia by agmatine. © 2012 The Authors Fundamental and Clinical Pharmacology © 2012 Société Française de Pharmacologie et de Thérapeutique.

Activation of G protein-coupled bile acid receptor, TGR5, induces smooth muscle relaxation via both Epac- and PKA-mediated inhibition of RhoA/Rho kinase pathway.

PubMed

Rajagopal, Senthilkumar; Kumar, Divya P; Mahavadi, Sunila; Bhattacharya, Sayak; Zhou, Ruizhe; Corvera, Carlos U; Bunnett, Nigel W; Grider, John R; Murthy, Karnam S

2013-03-01

The present study characterized the TGR5 expression and the signaling pathways coupled to this receptor that mediates the relaxation of gastric smooth muscle. TGR5 was detected in gastric muscle cells by RT-PCR and Western blotting. Treatment of cells with the TGR5-selective ligand oleanolic acid (OA) activated Gαs, but not Gαq, Gαi1, Gαi2, or Gαi3, and increased cAMP levels. OA did not elicit contraction, but caused relaxation of carbachol-induced contraction of gastric muscle cells from wild-type mice, but not tgr5(-/-) mice. OA, but not a selective exchange protein activated by cAMP (Epac) ligand (8-pCPT-2'-O-Me-cAMP), caused phosphorylation of RhoA and the phosphorylation was blocked by the PKA inhibitor, myristoylated PKI, and by the expression of phosphorylation-deficient mutant RhoA (S188A). Both OA and Epac ligand stimulated Ras-related protein 1 (Rap1) and inhibited carbachol (CCh)-induced Rho kinase activity. Expression of RhoA (S188A) or PKI partly reversed the inhibition of Rho kinase activity by OA but had no effect on inhibition by Epac ligand. However, suppression of Rap1 with siRNA blocked the inhibition of Rho kinase by Epac ligand, and partly reversed the inhibition by OA; the residual inhibition was blocked by PKI. Muscle relaxation in response to OA, but not Epac ligand, was partly reversed by PKI. We conclude that activation of TGR5 causes relaxation of gastric smooth muscle and the relaxation is mediated through inhibition of RhoA/Rho kinase pathway via both cAMP/Epac-dependent stimulation of Rap1 and cAMP/PKA-dependent phosphorylation of RhoA at Ser(188). TGR5 receptor activation on smooth muscle reveals a novel mechanism for the regulation of gut motility by bile acids.

Activation of G protein-coupled bile acid receptor, TGR5, induces smooth muscle relaxation via both Epac- and PKA-mediated inhibition of RhoA/Rho kinase pathway

PubMed Central

Rajagopal, Senthilkumar; Kumar, Divya P.; Mahavadi, Sunila; Bhattacharya, Sayak; Zhou, Ruizhe; Corvera, Carlos U.; Bunnett, Nigel W.; Grider, John R.

2013-01-01

The present study characterized the TGR5 expression and the signaling pathways coupled to this receptor that mediates the relaxation of gastric smooth muscle. TGR5 was detected in gastric muscle cells by RT-PCR and Western blotting. Treatment of cells with the TGR5-selective ligand oleanolic acid (OA) activated Gαs, but not Gαq, Gαi1, Gαi2, or Gαi3, and increased cAMP levels. OA did not elicit contraction, but caused relaxation of carbachol-induced contraction of gastric muscle cells from wild-type mice, but not tgr5−/− mice. OA, but not a selective exchange protein activated by cAMP (Epac) ligand (8-pCPT-2′-O-Me-cAMP), caused phosphorylation of RhoA and the phosphorylation was blocked by the PKA inhibitor, myristoylated PKI, and by the expression of phosphorylation-deficient mutant RhoA (S188A). Both OA and Epac ligand stimulated Ras-related protein 1 (Rap1) and inhibited carbachol (CCh)-induced Rho kinase activity. Expression of RhoA (S188A) or PKI partly reversed the inhibition of Rho kinase activity by OA but had no effect on inhibition by Epac ligand. However, suppression of Rap1 with siRNA blocked the inhibition of Rho kinase by Epac ligand, and partly reversed the inhibition by OA; the residual inhibition was blocked by PKI. Muscle relaxation in response to OA, but not Epac ligand, was partly reversed by PKI. We conclude that activation of TGR5 causes relaxation of gastric smooth muscle and the relaxation is mediated through inhibition of RhoA/Rho kinase pathway via both cAMP/Epac-dependent stimulation of Rap1 and cAMP/PKA-dependent phosphorylation of RhoA at Ser188. TGR5 receptor activation on smooth muscle reveals a novel mechanism for the regulation of gut motility by bile acids. PMID:23275618

A role for TREK1 in generating the slow afterhyperpolarization in developing starburst amacrine cells.

PubMed

Ford, Kevin J; Arroyo, David A; Kay, Jeremy N; Lloyd, Eric E; Bryan, Robert M; Sanes, Joshua R; Feller, Marla B

2013-05-01

Slow afterhyperpolarizations (sAHPs) play an important role in establishing the firing pattern of neurons that in turn influence network activity. sAHPs are mediated by calcium-activated potassium channels. However, the molecular identity of these channels and the mechanism linking calcium entry to their activation are still unknown. Here we present several lines of evidence suggesting that the sAHPs in developing starburst amacrine cells (SACs) are mediated by two-pore potassium channels. First, we use whole cell and perforated patch voltage clamp recordings to characterize the sAHP conductance under different pharmacological conditions. We find that this conductance was calcium dependent, reversed at EK, blocked by barium, insensitive to apamin and TEA, and activated by arachidonic acid. In addition, pharmacological inhibition of calcium-activated phosphodiesterase reduced the sAHP. Second, we performed gene profiling on isolated SACs and found that they showed strong preferential expression of the two-pore channel gene kcnk2 that encodes TREK1. Third, we demonstrated that TREK1 knockout animals exhibited an altered frequency of retinal waves, a frequency that is set by the sAHPs in SACs. With these results, we propose a model in which depolarization-induced decreases in cAMP lead to disinhibition of the two-pore potassium channels and in which the kinetics of this biochemical pathway dictate the slow activation and deactivation of the sAHP conductance. Our model offers a novel pathway for the activation of a conductance that is physiologically important.

14 CFR 33.57 - General conduct of block tests.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Section 33.57 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.57 General conduct of... that, if a separate engine is used for the endurance test it must be subjected to a calibration check...

14 CFR 33.57 - General conduct of block tests.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Section 33.57 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.57 General conduct of... that, if a separate engine is used for the endurance test it must be subjected to a calibration check...

14 CFR 33.57 - General conduct of block tests.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Section 33.57 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.57 General conduct of... that, if a separate engine is used for the endurance test it must be subjected to a calibration check...

14 CFR 33.57 - General conduct of block tests.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Section 33.57 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.57 General conduct of... that, if a separate engine is used for the endurance test it must be subjected to a calibration check...

14 CFR 33.57 - General conduct of block tests.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Section 33.57 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.57 General conduct of... that, if a separate engine is used for the endurance test it must be subjected to a calibration check...

The peroxynitrite donor 3-morpholinosydnonimine induces reversible changes in electrophysiological properties of neurons of the guinea-pig spinal cord.

PubMed

Ashki, N; Hayes, K C; Bao, F

2008-09-22

Elevated concentrations of nitric oxide (NO) and peroxynitrite (ONOO(-)) are present within the CNS following neurotrauma and are implicated in the pathogenesis of the accompanying neurologic deficits. We tested the hypothesis that elevated extracellular concentrations of ONOO(-), introduced by the donor 3-morpholinosydnonimine (SIN-1), induce reversible axonal conduction deficits in neurons of the guinea-pig spinal cord. The compound action potential (CAP) and compound membrane potential (CMP) of excised ventral cord white matter were recorded before, during, and after, bathing the tissue (30 min) in varying concentrations (0.125-2.0 mM) of SIN-1 (3.75-60 microM ONOO(-)). The principal results were rapid onset, concentration-dependent, reductions in amplitude of the CAP (P<0.05). At a concentration of 0.25 mM of SIN-1 the reduction in CAP amplitude was fully reversible and was not accompanied by any changes in CMP. At higher concentrations of SIN-1 (> or =0.5 mM) the reversibility was incomplete and there was concurrent depolarization of the CMP. These electrophysiological changes were not evident when the donor had been a priori depleted of ONOO(-) by uric acid or was co-administered with the ONOO(-) scavenger ebselen (3 mM). Immuno-fluorescence staining for nitrotyrosine (Ntyr) revealed extensive nitration of tyrosine residues in neurons exposed to higher concentrations of SIN-1. These results are the first to demonstrate that ONOO(-) induces reversible conduction deficits within axons of the spinal cord. The dissociation of CAP and CMP changes at low concentrations of SIN-1, when the CAP changes were reversible and there was no evidence of nitration of tyrosine residues, is consistent with ONOO(-)-induced alteration in Na+ channel conductance in the axolemma. The results support the view that ONOO(-) contributes to both reversible and non-reversible neurologic deficits following neurotrauma. The reversal of immune-mediated conduction deficits may contribute to spontaneous neurologic deficits following neurotrauma.

Degradable ketal-based block copolymer nanoparticles for anticancer drug delivery: a systematic evaluation.

PubMed

Louage, Benoit; Zhang, Qilu; Vanparijs, Nane; Voorhaar, Lenny; Vande Casteele, Sofie; Shi, Yang; Hennink, Wim E; Van Bocxlaer, Jan; Hoogenboom, Richard; De Geest, Bruno G

2015-01-12

Low solubility of potent (anticancer) drugs is a major driving force for the development of noncytotoxic, stimuli-responsive nanocarriers, including systems based on amphiphilic block copolymers. In this regard, we investigated the potential of block copolymers based on 2-hydroxyethyl acrylate (HEA) and the acid-sensitive ketal-containing monomer (2,2-dimethyl-1,3-dioxolane-4-yl)methyl acrylate (DMDMA) to form responsive drug nanocarriers. Block copolymers were successfully synthesized by sequential reversible addition-fragmentation chain transfer (RAFT) polymerization, in which we combined a hydrophilic poly(HEA)x block with a (responsive) hydrophobic poly(HEAm-co-DMDMAn)y copolymer block. The DMDMA content of the hydrophobic block was systematically varied to investigate the influence of polymer design on physicochemical properties and in vitro biological performance. We found that a DMDMA content higher than 11 mol % is required for self-assembly behavior in aqueous medium. All particles showed colloidal stability in PBS at 37 °C for at least 4 days, with sizes ranging from 23 to 338 nm, proportional to the block copolymer DMDMA content. Under acidic conditions, the nanoparticles decomposed into soluble unimers, of which the decomposition rate was inversely proportional to the block copolymer DMDMA content. Flow cytometry and confocal microscopy showed dose-dependent, active in vitro cellular uptake of the particles loaded with hydrophobic octadecyl rhodamine B chloride (R18). The block copolymers showed no intrinsic in vitro cytotoxicity, while loaded with paclitaxel (PTX), a significant decrease in cell viability was observed comparable or better than the two commercial PTX nanoformulations Abraxane and Genexol-PM at equal PTX dose. This systematic approach evaluated and showed the potential of these block copolymers as nanocarriers for hydrophobic drugs.

Cell block samples from malignant pleural effusion might be valid alternative samples for anaplastic lymphoma kinase detection in patients with advanced non-small-cell lung cancer.

PubMed

Zhou, Jianya; Yao, Hongtian; Zhao, Jing; Zhang, Shumeng; You, Qihan; Sun, Ke; Zou, Yinying; Zhou, Caicun; Zhou, Jianying

2015-06-01

To evaluate the clinical value of cell block samples from malignant pleural effusion (MPE) as alternative samples to tumour tissue for anaplastic lymphoma kinase (ALK) detection in patients with advanced non-small-cell lung cancer (NSCLC). Fifty-two matched samples were eligible for analysis. ALK status was detected by Ventana immunohistochemistry (IHC) (with the D5F3 clone), reverse transcription polymerase chain reaction (RT-PCR) and fluorescence in-situ hybridization (FISH) in MPE cell block samples, and by FISH in tumour tissue block samples. In total, ALK FISH results were obtained for 52 tumour tissue samples and 41 MPE cell block samples. Eight cases (15.4%) were ALK-positive in tumour tissue samples by FISH, and among matched MPE cell block samples, five were ALK-positive by FISH, seven were ALK-positive by RT-PCR, and eight were ALK-positive by Ventana IHC. The ALK status concordance rates between tumour tissue and MPE cell block samples were 78.9% by FISH, 98.1% by RT-PCR, and 100% by Ventana IHC. In MPE cell block samples, the sensitivity and specificity of Ventana IHC (100% and 100%) and RT-PCR (87.5% and 100%) were higher than those of FISH (62.5% and 100%). Malignant pleural effusion cell block samples had a diagnostic performance for ALK detection in advanced NSCLC that was comparable to that of tumour tissue samples. MPE cell block samples might be valid alternative samples for ALK detection when tissue is not available. Ventana IHC could be the most suitable method for ALK detection in MPE cell block samples. © 2014 John Wiley & Sons Ltd.

Leakage current reduction of vertical GaN junction barrier Schottky diodes using dual-anode process

NASA Astrophysics Data System (ADS)

Hayashida, Tetsuro; Nanjo, Takuma; Furukawa, Akihiko; Watahiki, Tatsuro; Yamamuka, Mikio

2018-04-01

The origin of the leakage current of a trench-type vertical GaN diode was discussed. We found that the edge of p-GaN is the main leakage spot. To reduce the reverse leakage current at the edge of p-GaN, a dual-anode process was proposed. As a result, the reverse blocking voltage defined at the leakage current density of 1 mA/cm2 of a vertical GaN junction barrier Schottky (JBS) diode was improved from 780 to 1,190 V, which is the highest value ever reported for vertical GaN Schottky barrier diodes (SBDs).