Explosive development of pectoral muscle fibres in large juvenile blue catfish Ictalurus furcatus.

As part of an effort on scaling of pectoral spines and muscles, the basis for growth was examined in six pectoral muscles in juvenile blue catfish Ictalurus furcatus, the largest catfish in North America. Fibre number increases slowly in fish from 13.0 to 26.4 cm in total length, doubles by 27.0 cm and remains stable in larger individuals. Simultaneously, mean fibre diameter decreases by half, caused by the addition of new small fibres, before increasing non-linearly in larger fish. The orders of magnitude disparity between the size at hatching and the size of large adults may have selected for rapid muscle fibre addition at a threshold size.

Avibactam and class C ß-lactamases: mechanism of inhibition, conservation of the binding pocket, and implications for resistance.

Avibactam is a novel non-ß-lactam ß-lactamase inhibitor that inhibits a wide range of ß-lactamases. These include class A, class C, and some class D enzymes, which erode the activity of ß-lactam drugs in multidrug-resistant pathogens like Pseudomonas aeruginosa and Enterobacteriaceae spp. Avibactam is currently in clinical development in combination with the ß-lactam antibiotics ceftazidime, ceftaroline fosamil, and aztreonam. Avibactam has the potential to be the first ß-lactamase inhibitor that might provide activity against class C-mediated resistance, which represents a growing concern in both hospital- and community-acquired infections. Avibactam has an unusual mechanism of action: it is a covalent inhibitor that acts via ring opening, but in contrast to other currently used ß-lactamase inhibitors, this reaction is reversible. Here, we present a high-resolution structure of avibactam bound to a class C ß-lactamase, AmpC, from P. aeruginosa that provided insight into the mechanism of both acylation and recyclization in this enzyme class and highlighted the differences observed between class A and class C inhibition. Furthermore, variants resistant to avibactam that identified the residues important for inhibition were isolated. Finally, the structural information was used to predict effective inhibition by sequence analysis and functional studies of class C ß-lactamases from a large and diverse set of contemporary clinical isolates (P. aeruginosa and several Enterobacteriaceae spp.) obtained from recent infections to understand any preexisting variability in the binding pocket that might affect inhibition by avibactam.

The importance of the Abn2 calcium cluster in the endo-1,5-arabinanase activity from Bacillus subtilis.

Arabinanase is a glycosyl hydrolase that is able to cleave the glycosidic bonds of α-1,5-L-arabinan, releasing arabino-oligosaccharides and L-arabinose. The enzyme has two domains, an N-terminal catalytic domain with a characteristic ß-propeller fold and a C-terminal domain whose function is unknown. A calcium ion, located near the catalytic site, serves to stabilize the N-terminal domain, but it has also been proposed to play a key role in the enzyme mechanism. The present work describes the structure of an inactive mutant of the wild-type enzyme (H318Q) and in which the calcium ion has been adventitiously replaced by nickel. These structural studies, together with functional and modelling studies, clearly support the role of the calcium ion in the overall reaction mechanism.

48Ca+249Bk fusion reaction leading to element Z = 117: long-lived α-decaying 270Db and discovery of 266Lr.

The superheavy element with atomic number Z=117 was produced as an evaporation residue in the (48)Ca+(249)Bk fusion reaction at the gas-filled recoil separator TASCA at GSI Darmstadt, Germany. The radioactive decay of evaporation residues and their α-decay products was studied using a detection setup that allowed measuring decays of single atomic nuclei with half-lives between sub-µs and a few days. Two decay chains comprising seven α decays and a spontaneous fission each were identified and are assigned to the isotope (294)117 and its decay products. A hitherto unknown α-decay branch in (270)Db (Z = 105) was observed, which populated the new isotope (266)Lr (Z = 103). The identification of the long-lived (T(1/2) = 1.0(-0.4)(+1.9) h) α-emitter (270)Db marks an important step towards the observation of even more long-lived nuclei of superheavy elements located on an "island of stability."

Evaluation of discordance measures in oncology studies with blinded independent central review of progression-free survival using an observational error model.

To confirm results obtained from local evaluation at investigational centers, many oncology studies utilize blinded independent central review (BICR) to make assessments of the primary endpoint, progression-free survival (PFS). The comparison of data often leads to large discordances between these observations, casting doubt on the reliability of the estimated treatment effects from these trials. Here we propose new statistics to measure discordance and evaluate their utility to detect bias in the local evaluation of progression relative to the standard measures of discordance. A new observational error model is proposed that can be used to describe the discordance in patient assessments between multiple readers.

Role of ammonium ionic liquid and Pd nanoparticles in cavitation-based graphite decontamination and recycling process.

Sonochemical recovery of radioactive contaminants from nuclear graphite has been demonstrated to be quite invaluable in recent studies. However, graphite is a soft material and is prone to erosion and wear. This restricts the recycle of graphite cleaned using ultrasound beyond a few decontamination cycles. Hence, it is an imperative to prevent the surface erosion of graphite in the sonic field. The current work studies the efficacy of ultrasound in decontaminating ceria contaminated graphite coupons using a cocktail of acids (0.25 M HNO3 - 1 M HCOOH - 0.2 M [N2H5][NO3]). Based on the superlative effects of ionic liquids in lubrication and erosion prevention, the effect of adding ionic liquid stabilized Pd nanoparticles to the leachate was also studied. It was observed that the Trioctylmethyl ammonium chloride (TOMAC) ionic liquid prevented the generation of the carbon residue due to a protective viscous layer formation reducing the mechanical effects of cavitation on graphite surface. It also helped in maintaining the porosity change in graphite microstructure around 5% after 15 cycles of decontamination. TOMAC also proved to offer better surface protection on graphite compared to imidazolium-based ILs, based on the change in compressive strength and porosity in different ionic liquids. The palladium nanoparticles, on the other hand, helped in reductive dissolution of ceria layer by acting as a reducing agent due to its lower reduction potential compared to cerium. With the surge in demand of graphite worldwide, a non-destructive decontamination process for graphite with no secondary waste generation is the need of the hour. This study is an attempt in that direction.

On the adsorption and reactivity of element 114, flerovium.

Flerovium (Fl, element 114) is the heaviest element chemically studied so far. To date, its interaction with gold was investigated in two gas-solid chromatography experiments, which reported two different types of interaction, however, each based on the level of a few registered atoms only. Whereas noble-gas-like properties were suggested from the first experiment, the second one pointed at a volatile-metal-like character. Here, we present further experimental data on adsorption studies of Fl on silicon oxide and gold surfaces, accounting for the inhomogeneous nature of the surface, as it was used in the experiment and analyzed as part of the reported studies. We confirm that Fl is highly volatile and the least reactive member of group 14. Our experimental observations suggest that Fl exhibits lower reactivity towards Au than the volatile metal Hg, but higher reactivity than the noble gas Rn.

Sonochemical recovery of uranium from nanosilica-based sorbent and its biohybrid.

Use of nanomaterials to remove uranium by adsorption from nuclear wastewater is widely applied, though not much work is focused on the recovery of uranium from the sorbents. The present work reports the recovery of adsorbed uranium from the microstructures of silica nanoparticles (SiO2M) and its functionalized biohybrid (fBHM), synthesized with Streptococcus lactis cells and SiO2M, intensified using ultrasound. Effects of temperature, concentration of leachant (nitric acid), sonic intensity, and operating frequency on the recovery as well as kinetics of recovery were thoroughly studied. A comparison with the silent operation demonstrated five and two fold increase due to the use of ultrasound under optimum conditions in the dissolution from SiO2M and fBHM respectively. Results of the subsequent adsorption studies using both the sorbents after sonochemical desorption have also been presented with an aim of checking the efficacy of reusing the adsorbent back in wastewater treatment. The SiO2M and fBHM adsorbed 69% and 67% of uranium respectively in the second cycle. The adsorption capacity of fBHM was found to reduce from 92% in the first cycle to 67% due to loss of adsorption sites in the acid treatment. Recovery and reuse of both the nuclear material and the sorbent (with some make up or activation) would ensure an effective nuclear remediation technique, catering to UN's Sustainable Development Goals.

Cavitation-assisted decontamination of yttria from graphite of different densities.

Yttria coated graphite crucibles are widely used to handle molten refractory and radioactive metals like uranium and plutonium. However, the coated layer suffers damages like cracking and peeling off owing to thermal cycles. As a result, removal of the yttria layer from the graphite surface is essential to ensure reuse of the crucible and minimization of radioactive waste. The present work investigates intensified dissolution of yttria from the coated graphite samples using ultrasound as a non-destructive decontamination technique to recycle the graphite substrate. The optimum conditions established for maximum dissolution were 8 M as acid strength, frequency of 30 kHz, temperature of 45 °C and power density of 8 W cm-2 that resulted in maximum dissolution of 52% in 30 min. Use of an oxidant H2O2 to the acid, did not yield any improvement in the dissolution kinetics, instead, increased oxidation of the graphite substrate was observed, leading to the anomalous weight gain of the graphite substrate despite surface erosion. Effect of ultrasound on the dissolution was pronounced, with almost a threefold increase compared to dissolution performed under silent conditions. Rates of dissolution of yttria from the substrate of different densities and pore size distribution were also studied. The dissolution was slowest from graphite of density 1.82 g cm-3 as the pore size distribution was conducive to accommodate the yttria particles. The dissolution in nitric acid followed ash layer diffusion controlled kinetics. The study has demonstrated the efficacy of application of ultrasound for accelerated decontamination of graphite substrates.

Production and decay of element 114: high cross sections and the new nucleus 277Hs.

The fusion-evaporation reaction 244Pu(48Ca,3-4n){288,289}114 was studied at the new gas-filled recoil separator TASCA. Thirteen correlated decay chains were observed and assigned to the production and decay of {288,289}114. At a compound nucleus excitation energy of E{*}=39.8-43.9 MeV, the 4n evaporation channel cross section was 9.8{-3.1}{+3.9} pb. At E^{*}=36.1-39.5 MeV, that of the 3n evaporation channel was 8.0{-4.5}{+7.4} pb. In one of the 3n evaporation channel decay chains, a previously unobserved α branch in 281Ds was observed (probability to be of random origin from background: 0.1%). This α decay populated the new nucleus 277Hs, which decayed by spontaneous fission after a lifetime of 4.5 ms.

Dielectric Elastomer Actuator Driven Soft Robotic Structures With Bioinspired Skeletal and Muscular Reinforcement.

Natural motion types found in skeletal and muscular systems of vertebrate animals inspire researchers to transfer this ability into engineered motion, which is highly desired in robotic systems. Dielectric elastomer actuators (DEAs) have shown promising capabilities as artificial muscles for driving such structures, as they are soft, lightweight, and can generate large strokes. For maximum performance, dielectric elastomer membranes need to be sufficiently pre-stretched. This fact is challenging, because it is difficult to integrate pre-stretched membranes into entirely soft systems, since the stored strain energy can significantly deform soft elements. Here, we present a soft robotic structure, possessing a bioinspired skeleton integrated into a soft body element, driven by an antagonistic pair of DEA artificial muscles, that enable the robot bending. In its equilibrium state, the setup maintains optimum isotropic pre-stretch. The robot itself has a length of 60 mm and is based on a flexible silicone body, possessing embedded transverse 3D printed struts. These rigid bone-like elements lead to an anisotropic bending stiffness, which only allows bending in one plane while maintaining the DEA's necessary pre-stretch in the other planes. The bones, therefore, define the degrees of freedom and stabilize the system. The DEAs are manufactured by aerosol deposition of a carbon-silicone-composite ink onto a stretchable membrane that is heat cured. Afterwards, the actuators are bonded to the top and bottom of the silicone body. The robotic structure shows large and defined bimorph bending curvature and operates in static as well as dynamic motion. Our experiments describe the influence of membrane pre-stretch and varied stiffness of the silicone body on the static and dynamic bending displacement, resonance frequencies and blocking forces. We also present an analytical model based on the Classical Laminate Theory for the identification of the main influencing parameters. Due to the simple design and processing, our new concept of a bioinspired DEA based robotic structure, with skeletal and muscular reinforcement, offers a wide range of robotic application.

Soybean Host Plant Resistance to Megacopta cribraria (Hemiptera: Plataspidae) and the Potential Role of Leaf Trichome Density.

Megacopta cribraria (F.) (Hemiptera: Plataspidae) is an invasive pest of soybean that has spread across the southeastern United States since its initial discovery in 2009 in Georgia. Previous studies in the southeastern states have documented both the population dynamics of this pest and host plant resistance (HPR) among soybean varieties, although the specific mechanisms of HPR remain unknown. The objectives of this study were, therefore, to 1) quantify field resistance to M. cribraria in multiple soybean varieties in two states previously affected by severe M. cribraria infestations, North Carolina (NC) and South Carolina (SC); and 2) study the role of soybean trichome density in imparting resistance against M. cribraria. Soybean variety 'Camp' was least attractive to M. cribraria, through time and locations, suggesting consistent resistance. Other varieties showed variable performance among the locations and sampling dates. A significant difference in trichome density was evident. However, there was no correlation between trichome density and M. cribraria infestation. Compared to a previously published study in the same location, when M. cribraria adults emerging from overwintering dispersed into soybeans, in our study only first-generation adults dispersed into soybeans. Considering the current trend of significantly lower M. cribraria infestation rates in North and South Carolina, this pest may be finally succumbing to indigenous natural enemies and should be managed by incorporating integrated pest management tactics, such as HPR, that help conserve natural enemy populations.

Mechanisms of Soybean Host-Plant Resistance Against Megacopta cribraria (Hemiptera: Plataspidae).

A number of soybean varieties traditionally bred for resistance to various soybean arthropod pests have been identified as resistant to Megacopta cribraria (F.) (Hemiptera: Plataspidae). However, the mechanisms of host-plant resistance (HPR) in this system are not understood. The goal of this study was to identify the mechanisms of resistance by examining the role of plant volatile organic compounds (VOCs) and free amino acids (FAAs) among 16 soybean varieties. Choice and no-choice cage experiments identified several soybean varieties that demonstrated antixenosis as well as antibiosis. However, resistance varied over time in certain soybean varieties, such as N02-7002 and PI567352B. Mean nymph number from choice experiments had positive correlations with the FAAs asparagine, tryptophan, alanine, phenylanaline, and serine; negative correlation with leucine and threonine. Four plant volatiles, hexanal, 2-pentylfuran, beta-cyclocitral, and cis-9-hexadecenal, were positively correlated with subsequent nymph development, whereas n-hexadecenoic acid was negatively correlated with nymph number only, in adult choice cage experiments. This study contributes to understanding the mechanisms of HPR through associations with plant VOCs and FAAs in relation to M. cribraria development and provides useful knowledge for developing soybean varieties for M. cribraria management.

Chemical modification of carotid body chemoreception by sulfhydryls.

Sulfhydryl reagents cause striking augmentation of the chemoreceptor responses of the carotid body to hypoxia. This indicates that a cellular plasma membrane protein with a reactive sulfhydryl group is a constituent part of the chemoreceptor architecture and provides a means of identification, localization, and isolation of the protein.

Systemic manifestations in chronic arsenic toxicity in absence of skin lesions in West Bengal.

BACKGROUND & OBJECTIVE: Pigmentation and keratosis are the prerequisites to diagnose arsenicosis. However, many systemic manifestations occur in association with pigmentation and keratosis in people exposed to chronic drinking of arsenic contaminated water. The present study aim to find out whether systemic manifestations occur in significant number of cases in arsenic exposed people in the absence of skin lesions in an affected district in West Bengal, India. METHODS: A cross-sectional study was carried out in South 24 Parganas, an arsenic affected district of West Bengal, India. Both dermatological and systemic manifestations were recorded and water samples collected for arsenic analysis from 7683 participants. A correlation of systemic manifestations in relation to arsenic exposure was carried out in subjects having no arsenical skin lesion. Prevalence odds ratio (POR) was calculated for each outcome comparing those with high arsenic exposure with those with lowest exposure. RESULTS: The frequency of occurrence of various clinical manifestations like weakness, anaemia, diarrhoea, hepatomegaly and lung disease was found to be significantly higher among participants drinking water having arsenic concentration > or = 50 microg/l in comparison to those taking water with arsenic content below this level. Further, there was increased occurrence of these manifestations with increasing concentration of arsenic level in drinking water, and this followed a dose-response relationship. INTERPRETATION & CONCLUSION: It appears that it is worthwhile to include people with systemic manifestations in absence of skin lesions with evidence of arsenic exposure as suspected cases of arsenicosis for case detection and in surveillance programme.

Calcium sensitivity for hypoxia in PGNs with PC-12 cells in co-culture.

Calcium sensitivity of petrosal ganglion neurons (PGNs) to chemical stimuli with and without PC-12 cells in co-culture instead of glomus is not known- the idea being that two types of unusual cells could form synapse and provide a model for studies of chemotransduction. Calcium levels in the PGNs were measured in the presence of different chemical stimuli in the bath medium. Remarkably, the PGNs alone were not sensitive to hypoxia (10 torr), PCO ( approximately 300 torr in normoxa) nor to ATP (100microM) but they developed the sensitivity to these stimuli in synaptic contact with PC-12 cells. The sharp rise in calcium level was suppressed (2/3) by suramin (100microM), a purinergic blocker, and the remaining 1/3 was blocked by hexomethonium, a cholinergic blocker. Taken together, these observations suggest that PGNs developed neurotransmission when in contact with PC-12 cells, as if the latter substituting for glomus cells, thus providing a model for chemotransduction studies. The reason for the insensitivity of PGNs alone to the chemical stimuli is unknown at this time.

Carotid body sensory discharge and glomus cell HIF-1 alpha are regulated by a common oxygen sensor.

The carotid body responds to both acute and more prolonged periods of lowered oxygen pressure. In the acute response, the decrease in oxygen pressure is coupled to increased afferent neural activity while the latter involves, at least in part, increase in the hypoxia inducible transcription factor HIF-1 alpha. In this paper, we summarize evidence that both the acute changes in neural activity and the longer term adaptive changes linked to HIF-1 alpha induction share the same oxygen sensor, mitochondrial cytochrome c oxidase.

Neuroglobin in aging carotid bodies.

Neuroglobin (Ngb) is a member of the vertebrate globin family expressed particularly in the brain and in the retina. Ngb is concentrated in the mitochondria-containing areas of neurons, and its distribution is correlated with oxygen consumption rates. Previously we have shown that Ngb is expressed in carotid body (CB) tissues. Considering that hypoxia and aging may be linked through a series of adaptive and protective mechanisms (e.g. reduction in mitochondrial numbers), we investigate the role of Ngb during aging and hypoxia. Two groups of six rats (age-matched 3 and 24 months old) were kept in room air as a control groups, the others two groups were kept in a Plexiglas chamber for 12 days in chronic hypoxia (10-12% inspired oxygen). The presence of Ngb in the CB tissue was detected by immunohistochemistry using a polyclonal antibody. Ngb immunoreactivity was significantly higher in CB tissues from young rats exposed to chronic intermittent hypoxia, whereas CB tissues from old rats did not show any significant increase in Ngb levels after hypoxia. Similar to hemoglobin, Ngb may act as a respiratory protein by reversibly binding gaseous ligands NO and O(2) and could act as a NO scavenger and participate in detoxification of Reactive Oxygen Species (ROS) generated under hypoxic conditions.

Mint oil (Mentha spicata Linn.) offers behavioral radioprotection: a radiation-induced conditioned taste aversion study.

Mentha spicata Linn. (mint), a herb well known for its gastroprotective properties in the traditional system of medicine has been shown to protect against radiation-induced lethality, and recently its constituents have been found to possess calcium channel antagonizing properties. The present study examined the behavioral radioprotective efficacy of mint oil (obtained from Mentha spicata), particularly in mitigating radiation-induced conditioned taste aversion (CTA), which has been proposed as a behavioral endpoint that is mediated by the toxic effects of gamma radiation on peripheral systems, primarily the gastrointestinal system in the Sprague-Dawley rat model. Intraperitoneal administration of Mentha spicata oil 10% (v/v), 1 h before 2 Gy gamma radiation, was found to render significant radioprotection against CTA (p < 0.05), by blocking the saccharin avoidance response within 5 post-treatment observational days, with the highest saccharin intake being observed on day 5. This finding clearly demonstrates that gastroprotective and calcium channel antagonizing properties of Mentha spicata can be effectively utilized in preventing radiation-induced behavioral changes.

A preliminary investigation into the use of FTIR microscopy as a probe for the identification of bullet entrance holes and the distance of firing.

FTIR spectroscopy has been found to be a valuable probe for the analysis of the distribution of organic components such as nitroglycerine in gunshot residues deposited on and around the bullet entrance hole of the clothing of the victim in short range firearm discharges. The method can be utilised for the detection and estimation of organic gunshot residues (OGSR) on the hands and clothing of the shooter. The method is specific and sensitive and is likely to be free from interference from, for example, environmental pollution. The method shows potential to be utilised as a suitable alternative to the widely used SEM-EDX analysis of the total contents of lead, barium and antimony present in the gunshot deposits around the bullet entrance hole. The method was tested in the laboratory and the results were validated by Gas Chromatography-Mass Spectrometry (GC-MS).