bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interplay among distinct Ca2+ conductances drives Ca2+ sparks/spontaneous transient outward currents in rat cerebral arteries
Authors: Hashad Ahmed M. , Mazumdar Neil , Romero Monica , Nygren Anders , Bigdely‐Shamloo Kamran , Harraz Osama F. , Puglisi Jose L. , Vigmond Edward J. , Wilson Sean M. , Welsh Donald G. 
Published: November 2016

Key points
Distinct Ca2+ channels work in a coordinated manner to grade Ca2+ spark/spontaneous transient outward currents (STOCs) in rat cerebral arteries.
The relative contribution of each Ca2+ channel to Ca2+ spark/STOC production depends upon their biophysical properties and the resting membrane potential of smooth muscle.
Na+/Ca2+ exchanger, but not TRP channels, can also facilitate STOC production.
AbstractCa2+ sparks are generated in a voltage‐dependent manner to initiate spontaneous transient outward currents (STOCs), events that moderate arterial constriction. In this study, we defined the mechanisms by which membrane depolarization increases Ca2+ sparks and subsequent STOC production. Using perforated patch clamp electrophysiology and rat cerebral arterial myocytes, we monitored STOCs in the presence and absence of agents that modulate Ca2+ entry. Beginning with CaV3.2 channel inhibition, Ni2+ was shown to decrease STOC frequency in cells held at hyperpolarized (−40 mV) but not depolarized (−20 mV) voltages. In contrast, nifedipine, a CaV1.2 inhibitor, markedly suppressed STOC frequency at −20 mV but not −40 mV. These findings aligned with the voltage‐dependent profiles of L‐ and T‐type Ca2+ channels. Furthermore, computational and experimental observations illustrated that Ca2+ spark production is intimately tied to the activity of both conductances. Intriguingly, this study observed residual STOC production at depolarized voltages that was independent of CaV1.2 and CaV3.2. This residual component was insensitive to TRPV4 channel modulation and was abolished by Na+/Ca2+ exchanger blockade. In summary, our work highlights that the voltage‐dependent triggering of Ca2+ sparks/STOCs is not tied to a single conductance but rather reflects an interplay among multiple Ca2+ permeable pores with distinct electrophysiological properties. This integrated orchestration enables smooth muscle to grade Ca2+ spark/STOC production and thus precisely tune negative electrical feedback.
Study of Heat and Mass Transfer in MgCl2/NH3 Thermo-Chemical Batteries
Authors: Hedayat Mofidi Seyyed Ali , Udell Kent S. 
Published: November 2016

Intermittency of sustainable energy or waste heat availability calls for energy storage systems such as thermal batteries. Thermo-chemical batteries are particularly appealing for energy storage applications due to their high energy densities and ability to store thermal energy as chemical energy for long periods of time without any energy loss. Thermo-chemical batteries based on a reversible solid-gas (MgCl2 - NH3) reactions and NH3 liquid-gas phase change are of specific interest since the kinetics of absorption are fast and the heat transfer rates for liquid — vapor phase change are high. Thus, a thermo-chemical battery based on reversible reaction between magnesium chloride and ammonia was studied.
Experimental studies were conducted on a reactor in which temperature profiles within the solid matrix and pressure and flow rates of gas were obtained during charging processes. A numerical model based on heat and mass transfer within the salt and salt-gas reactions was developed to simulate the absorption processes within the solid matrix and the results were compared with experimental data. The studies were used to determine dominant heat and mass transfer processes within the salt.
It is shown that for high permeability materials, heat transfer is the dominant factor in determining reaction rates. However increasing thermal conductivity might decrease permeability and reduce reaction rates. The effect of constraining mass flow rate on the temperature and reaction propagation is also studied. These results show that optimized heat and mass transfer within the solid-gas reactor will lead to improved performance for heating and air conditioning applications.
Design and Modeling of Light-Trapping Tubular Receiver Panels
Authors: Christian Joshua M. , Ortega Jesus D. , Ho Clifford K. , Yellowhair Julius 
Published: November 2016

Multiple receiver designs have been evaluated for improved optics and efficiency gains including flat panel, vertical-finned flat panel, horizontal-finned flat panel, and radially finned. Ray tracing using SolTrace was performed to understand the light-trapping effects of the finned receivers. Re-reflections of the fins to other fins on the receiver were captured to give an overall effective solar absorptance.
The ray tracing, finite element analysis, and previous computational fluid dynamics showed that the horizontal-finned flat panel produced the most efficient receiver with increased light-trapping and lower overall heat loss. The effective solar absorptance was shown to increase from an intrinsic absorptance of 0.86 to 0.96 with ray trace models. The predicted thermal efficiency was shown in CFD models to be over 95%. The horizontal panels produce a re-circulating hot zone between the panel fins reducing convective loss resulting in a more efficient receiver. The analysis and design of these panels are described with additional engineering details on testing a flat panel receiver and the horizontal-finned receiver at the National Solar Thermal Test Facility. Design considerations include the structure for receiver testing, tube sizing, surrounding heat shielding, and machinery for cooling the receiver tubes.
Evaluation of Hybrid Nuclear Energy Systems
Authors: McDaniel Robin J. 
Published: November 2016

Small Modular Reactor (SMR) technologies have been recently deemed by the DOE as clean energy, a low carbon-dioxide emitting “alternative energy” source. Recent UN Sustainability Goals and Global Climate Talks to reduce the anthropomorphic Carbon-Dioxide atmospheric concentrations signal a renewed interest and need for nuclear power. The objective of this paper is to present an improved approach to the evaluation of “Hybrid Nuclear Energy Systems”. A hybrid energy system is defined as an energy system that utilizes two or more sources of energy to be used in single or multiple applications. Traditional single sourced energy or power systems require the amount of energy creation and the production of usable power to be carefully balanced. With the introduction of multiple energy sources, loads, and energy capacitors, the design, simulation, and operation of such hybrid systems requires a new approach to analysis and control. This paper introduces three examples of “Hybrid Nuclear Energy Systems”, for large scale power, industrial heat, and electricity generation. The system component independence, reliability, availability, and dynamic control aspects, coupled with component operational decisions presents a new way to optimize energy production and availability. Additional novel hybrid hydro-nuclear systems, concentrated solar-nuclear power desalination systems, and nuclear-insitu petroleum extraction systems are compared. The design aspects of such hybrid systems suitable for process heat, electricity generation, and/or desalination applications are discussed. After a multiple-year research study of past hybrid reactor designs and recent system proposals, the following design evaluation approach is the result of analysis of the best concepts discovered.
This review of existing literature has summerized that postulated benefits of Hybrid Nuclear Sytems are; reduced greenhouse gas emissions, increased energy conversion efficiency, high reliability of electricity supply and consistent power quality, reduced fossil fuel dependence, less fresh water consumption, conversion of local coal or shale into higher value fuels, while lowering the risks and costs.
As these proposed hybrid systems are interdisciplinary in nature, they will require a new multidisciplinary approach to systems evaluation.
Determining the Potential of Salinity Gradient Energy Source Using an Exergy Analysis
Authors: Emdadi Arash , Zenouzi Mansour , Kowalski Gregory J. 
Published: November 2016

Mixing of fresh (river) water and salty water (seawater or saline brine) in a control fashion would produces an electrical energy known as salinity gradient energy (SGE). Two main conversion technologies of SGE are membrane-based processes; pressure retarded osmosis (PRO) and reverse electrodialysis (RED). In PRO, semipermeable membranes placed between the two streams of solutions allow the transport of water from low-pressure diluted solution to high-pressure concentrated solution. RED requires two alternating semipermeable membranes that allow the diffusion of the ions but not the flow of H2O. Lifetime and power density of the semipermeable membrane are two main factors affecting on deployment of PRO and RED. Semipermeable membranes with lifetime greater than 10 years and power density higher than 5 W/m2 would lead to faster development of this conversion technology.
An exergy analysis of an SGE system of sea-river can be applied to calculate the maximum potential power for electricity generation. Seawater is taken as reference environment (global dead state) for calculating the exergy of water since the seawater is the final reservoir. Once the fresh water is mixed with water of the sea or lake it becomes unuseful for human, agricultural or industrial uses loses all its exergy. Aqueous sodium chloride solution model is used in this study to calculate the thermodynamic properties of seawater. This model does not consider seawater as an ideal model and provides accurate thermodynamics properties of sodium chloride solution. As a case study, exergy calculation of Iran’s Urmia Lake-GadarChay River system. The chemical exergy analysis considers sodium chloride (NaCl) as main salt in the water of Lake Urmia. The sodium chloride concentration is more than 200 g/L in recent years. Based on the exergy results the potential power of this system is 329 MW. This results indicates a high potential for constructing power plant for salinity gradient energy conversion.
A preclinical microbeam facility with a conventional x‐ray tube
Authors: Bartzsch Stefan , Cummings Craig , Eismann Stephan , Oelfke Uwe 
Published: November 2016

Purpose:Microbeam radiation therapy is an innovative treatment approach in radiation therapy that uses arrays of a few tens of micrometer wide and a few hundreds of micrometer spaced planar x‐ray beams as treatment fields. In preclinical studies these fields efficiently eradicated tumors while normal tissue could effectively be spared. However, development and clinical application of microbeam radiation therapy is impeded by a lack of suitable small scale sources. Until now, only large synchrotrons provide appropriate beam properties for the production of microbeams.Methods:In this work, a conventional x‐ray tube with a small focal spot and a specially designed collimator are used to produce microbeams for preclinical research. The applicability of the developed source is demonstrated in a pilot in vitro experiment. The properties of the produced radiation field are characterized by radiochromic film dosimetry.Results:50 μm wide and 400 μm spaced microbeams were produced in a 20 × 20 mm2 sized microbeam field. The peak to valley dose ratio ranged from 15.5 to 30, which is comparable to values obtained at synchrotrons. A dose rate of up to 300 mGy/s was achieved in the microbeam peaks. Analysis of DNA double strand repair and cell cycle distribution after in vitro exposures of pancreatic cancer cells (Panc1) at the x‐ray tube and the European Synchrotron leads to similar results. In particular, a reduced G2 cell cycle arrest is observed in cells in the microbeam peak region.Conclusions:At its current stage, the source is restricted to in vitro applications. However, moderate modifications of the setup may soon allow in vivo research in mice and rats.
Automatic segmentation of right ventricle in cardiac cine MR images using a saliency analysis
Authors: Atehortúa Angélica , Zuluaga Maria A. , García Juan D. , Romero Eduardo 
Published: November 2016

Purpose:Accurate measurement of the right ventricle (RV) volume is important for the assessment of the ventricular function and a biomarker of the progression of any cardiovascular disease. However, the high RV variability makes difficult a proper delineation of the myocardium wall. This paper introduces a new automatic method for segmenting the RV volume from short axis cardiac magnetic resonance (MR) images by a salient analysis of temporal and spatial observations.Methods:The RV volume estimation starts by localizing the heart as the region with the most coherent motion during the cardiac cycle. Afterward, the ventricular chambers are identified at the basal level using the isodata algorithm, the right ventricle extracted, and its centroid computed. A series of radial intensity profiles, traced from this centroid, is used to search a salient intensity pattern that models the inner–outer myocardium boundary. This process is iteratively applied toward the apex, using the segmentation of the previous slice as a regularizer. The consecutive 2D segmentations are added together to obtain the final RV endocardium volume that serves to estimate also the epicardium.Results:Experiments performed with a public dataset, provided by the RV segmentation challenge in cardiac MRI, demonstrated that this method is highly competitive with respect to the state of the art, obtaining a Dice score of 0.87, and a Hausdorff distance of 7.26 mm while a whole volume was segmented in about 3 s.Conclusions:The proposed method provides an useful delineation of the RV shape using only the spatial and temporal information of the cine MR images. This methodology may be used by the expert to achieve cardiac indicators of the right ventricle function.
A Two-Component Regulatory System Impacts Extracellular Membrane-Derived Vesicle Production in Group A Streptococcus
Authors: Resch Ulrike , Tsatsaronis James Anthony , Le Rhun Anaïs , Stübiger Gerald , Rohde Manfred , Kasvandik Sergo , Holzmeister Susanne , Tinnefeld Philip , Wai Sun Nyunt , Charpentier Emmanuelle 
Published: November 2016

ABSTRACT
Export of macromolecules via extracellular membrane-derived vesicles (MVs) plays an important role in the biology of Gram-negative bacteria. Gram-positive bacteria have also recently been reported to produce MVs; however, the composition and mechanisms governing vesiculogenesis in Gram-positive bacteria remain undefined. Here, we describe MV production in the Gram-positive human pathogen group A streptococcus (GAS), the etiological agent of necrotizing fasciitis and streptococcal toxic shock syndrome. M1 serotype GAS isolates in culture exhibit MV structures both on the cell wall surface and in the near vicinity of bacterial cells. A comprehensive analysis of MV proteins identified both virulence-associated protein substrates of the general secretory pathway in addition to “anchorless surface proteins.” Characteristic differences in the contents, distributions, and fatty acid compositions of specific lipids between MVs and GAS cell membrane were also observed. Furthermore, deep RNA sequencing of vesicular RNAs revealed that GAS MVs contained differentially abundant RNA species relative to bacterial cellular RNA. MV production by GAS strains varied in a manner dependent on an intact two-component system, CovRS, with MV production negatively regulated by the system. Modulation of MV production through CovRS was found to be independent of both GAS cysteine protease SpeB and capsule biosynthesis. Our data provide an explanation for GAS secretion of macromolecules, including RNAs, lipids, and proteins, and illustrate a regulatory mechanism coordinating this secretory response.

IMPORTANCE
Group A streptococcus (GAS) is a Gram-positive bacterial pathogen responsible for more than 500,000 deaths annually. Establishment of GAS infection is dependent on a suite of proteins exported via the general secretory pathway. Here, we show that GAS naturally produces extracellular vesicles with a unique lipid composition that are laden with proteins and RNAs. Interestingly, both virulence-associated proteins and RNA species were found to be differentially abundant in vesicles relative to the bacteria. Furthermore, we show that genetic disruption of the virulence-associated two-component regulator CovRS leads to an increase in vesicle production. This study comprehensively describes the protein, RNA, and lipid composition of GAS-secreted MVs and alludes to a regulatory system impacting this process.
Metabolism of Toxic Sugars by Strains of the Bee Gut Symbiont Gilliamella apicola
Authors: Zheng Hao , Nishida Alex , Kwong Waldan K. , Koch Hauke , Engel Philipp , Steele Margaret I. , Moran Nancy A. 
Published: November 2016

ABSTRACT

Social bees collect carbohydrate-rich food to support their colonies, and yet, certain carbohydrates present in their diet or produced through the breakdown of pollen are toxic to bees. The gut microbiota of social bees is dominated by a few core bacterial species, including the Gram-negative species
Gilliamella apicola
. We isolated 42 strains of
G. apicola
from guts of honey bees and bumble bees and sequenced their genomes. All of the
G. apicola
strains share high 16S rRNA gene similarity, but they vary extensively in gene repertoires related to carbohydrate metabolism. Predicted abilities to utilize different sugars were verified experimentally. Some strains can utilize mannose, arabinose, xylose, or rhamnose (monosaccharides that can cause toxicity in bees) as their sole carbon and energy source. All of the
G. apicola
strains possess a
manO
-associated mannose family phosphotransferase system; phylogenetic analyses suggest that this was acquired from
Firmicutes
through horizontal gene transfer. The metabolism of mannose is specifically dependent on the presence of mannose-6-phosphate isomerase (MPI). Neither growth rates nor the utilization of glucose and fructose are affected in the presence of mannose when the gene encoding MPI is absent from the genome, suggesting that mannose is not taken up by
G. apicola
strains which harbor the phosphotransferase system but do not encode the MPI. Given their ability to simultaneously utilize glucose, fructose, and mannose, as well as the ability of many strains to break down other potentially toxic carbohydrates,
G. apicola
bacteria may have key roles in improving dietary tolerances and maintaining the health of their bee hosts.

IMPORTANCE
Bees are important pollinators of agricultural plants. Our study documents the ability of
Gilliamella apicola
, a dominant gut bacterium in honey bees and bumble bees, to utilize several sugars that are harmful to bee hosts. Using genome sequencing and growth assays, we found that the ability to metabolize certain toxic carbohydrates is directly correlated with the presence of their respective degradation pathways, indicating that metabolic potential can be accurately predicted from genomic data in these gut symbionts. Strains vary considerably in their range of utilizable carbohydrates, which likely reflects historical horizontal gene transfer and gene deletion events. Unlike their bee hosts,
G. apicola
bacteria are not detrimentally affected by growth on mannose-containing medium, even in strains that cannot metabolize this sugar. These results suggest that
G. apicola
may be an important player in modulating nutrition in the bee gut, with ultimate effects on host health.
Hepatitis C Virus Proteins Interact with the Endosomal Sorting Complex Required for Transport (ESCRT) Machinery via Ubiquitination To Facilitate Viral Envelopment
Authors: Barouch-Bentov Rina , Neveu Gregory , Xiao Fei , Beer Melanie , Bekerman Elena , Schor Stanford , Campbell Joseph , Boonyaratanakornkit Jim , Lindenbach Brett , Lu Albert , Jacob Yves , Einav Shirit 
Published: November 2016

ABSTRACT

Enveloped viruses commonly utilize late-domain motifs, sometimes cooperatively with ubiquitin, to hijack the
e
ndosomal
s
orting
c
omplex
r
equired for
t
ransport (ESCRT) machinery for budding at the plasma membrane. However, the mechanisms underlying budding of viruses lacking defined late-domain motifs and budding into intracellular compartments are poorly characterized. Here, we map a network of hepatitis C virus (HCV) protein interactions with the ESCRT machinery using a mammalian-cell-based protein interaction screen and reveal nine novel interactions. We identify HRS (hepatocyte growth factor-regulated tyrosine kinase substrate), an ESCRT-0 complex component, as an important entry point for HCV into the ESCRT pathway and validate its interactions with the HCV nonstructural (NS) proteins NS2 and NS5A in HCV-infected cells. Infectivity assays indicate that HRS is an important factor for efficient HCV assembly. Specifically, by integrating capsid oligomerization assays, biophysical analysis of intracellular viral particles by continuous gradient centrifugations, proteolytic digestion protection, and RNase digestion protection assays, we show that HCV co-opts HRS to mediate a late assembly step, namely, envelopment. In the absence of defined late-domain motifs, K63-linked polyubiquitinated lysine residues in the HCV NS2 protein bind the HRS ubiquitin-interacting motif to facilitate assembly. Finally, ESCRT-III and VPS/VTA1 components are also recruited by HCV proteins to mediate assembly. These data uncover involvement of ESCRT proteins in intracellular budding of a virus lacking defined late-domain motifs and a novel mechanism by which HCV gains entry into the ESCRT network, with potential implications for other viruses.

IMPORTANCE
Viruses commonly bud at the plasma membrane by recruiting the host ESCRT machinery via conserved motifs termed late domains. The mechanism by which some viruses, such as HCV, bud intracellularly is, however, poorly characterized. Moreover, whether envelopment of HCV and other viruses lacking defined late domains is ESCRT mediated and, if so, what the entry points into the ESCRT pathway are remain unknown. Here, we report the interaction network of HCV with the ESCRT machinery and a critical role for HRS, an ESCRT-0 complex component, in HCV envelopment. Viral protein ubiquitination was discovered to be a signal for HRS binding and HCV assembly, thereby functionally compensating for the absence of late domains. These findings characterize how a virus lacking defined late domains co-opts ESCRT to bud intracellularly. Since the ESCRT machinery is essential for the life cycle of multiple viruses, better understanding of this virus-host interplay may yield targets for broad-spectrum antiviral therapies.