bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Study on Mitigation of Heat Transfer Deterioration in Supercritical CO2 Heat Exchanger Application
Authors: Wong Kin Wing , Cheng Hui , Zhao Jiyun 
Published: October 2017

With the advantages of the thermophysical property of supercritical carbon dioxide (SCO2), SCO2 has been proposed for being used as the coolant of the secondary system in a nuclear reactor to promote a higher thermal efficiency. However, heat transfer deterioration (HTD) in supercritical fluid became a potential operational problem for the supercritical heat exchanger. Understanding of HTD is importance to heat exchanger tube design.
In this paper, both circular and annular tube with the same sectional area is simulated using the ANSYS FLUENT 15.0 with Shear Stress Transport (SST) turbulence model. In general, the SST model can accurately predict the position of HTD peak as found in the experiment but with a difference between the simulated and experimental value of the peak. Nevertheless, the SST model is still regarded as the turbulence model in modeling supercritical carbon dioxide heat transfer in ANSYS FLUENT. Computational Fluid Dynamics (CFD) simulation was performed for SCO2 on 8.42 MPa with an inlet temperature of 312.15K under heat flux value of 110 kW/m2 to illustrate the effect of heat transfer deterioration in the circular and annular tube. Second, the effect of turbulence augmentation to wall temperature are investigated by placing the semi-circular obstacles at the heated wall of the circular tube. The result showed that the addition of Vortex Generator (VG) could lessen the HTD effect and followed by the smoothing effect of the wall temperature along the downstream of the tube.
Modeling and Experiments of a Passive Decay Heat Removal System for Advanced Nuclear Reactors
Authors: Bersano Andrea , De Salve Mario , Bertani Cristina , Falcone Nicolò , Panella Bruno 
Published: October 2017

Within the field of research and development of innovative nuclear reactors, in particular Generation IV reactors and Small Modular Reactors (SMR), the design and the improvement of safety systems play a crucial role. Among all the safety systems high attention is dedicated to passive systems that do not need external energy to operate, with a very high reliability also in the case of station blackout, and which are largely used in evolutionary technology reactors.
The aim of this work is the experimental and numerical analysis of a passive system that operates in natural circulation in order to study the mechanism and the efficiency of heat removal. The final goal is the development of a methodology that can be used to study this class of systems and to assess the thermal-hydraulic code RELAP5 for these specific applications. Starting from a commercial size system, which is the decay heat removal system of the experimental lead cooled reactor ALFRED, an experimental facility has been designed, built and tested with the aim of studying natural circulation in passive systems for nuclear applications. The facility has been simulated and optimized using the thermal-hydraulic code RELAP5-3D. During the experimental tests, temperatures and pressures are measured and the experimental results are compared with the ones predicted by the code.
The results show that the system operates effectively, removing the given thermal power. The code can predict well the experimental results but high attention must be dedicated to the modeling of components where non-condensable gases are present (condenser pool and surrounding ambient). This facility will be also used to validate the scaling laws among systems that operate in natural circulation.
Preparation and Co (II) Removal of ZnO/Poly-Piperazineamide Nanofiltration Membranes
Authors: Zhang Xiaoguang , Chen Xuexing , Chen Qingchun , Deng Zhaolong , Liu Yan , Chen Rong , Deng Huiyu 
Published: October 2017

A series of nanofiltration membranes were prepared by interfacial polymerization of piperazine and terephthaloyl chloride on the surface of polyacrylonitrile (PAN) ultrafiltration membranes. ZnO nanoparticles were incorporated in the active separation layer to modify the performances of the membranes. The preparation conditions as the monomer concentration, dosage of nano-ZnO particles and the reaction time on removal of a simulated radioactive nuclide Co (II) were investigated.
Fourier transform infrared in attenuated total reflection mode verified the formation of polyamide on the PAN ultrafiltration membrane. The scanning electron microscope images showed that the nano-ZnO particles can homogeneously fixed on the membrane surface. The retention of Co (II) increased with increasing the dosage of nano-ZnO in the range of 0∼0.03 g. Further adding more nano-ZnO, the rejection rate of Co (II) first decreased and then increased. The concentration of piperazine and terephthaloyl chloride showed similar effect on removal of Co (II) ion. 5 minutes polymerization time was sufficient to form an active separation layer on the substrate membrane which changed the separation mechanism from ultrafiltration to nanofiltration. The separation performance of NF3 prepared by the following conditions was optimum: 0.03g nano-ZnO, 0.6 wt% piperazine, 0.5 wt% terephthaloyl chloride, and the reaction time was 15 min. The rejection rates of 1000 mg/L Na2SO4 and Co2+ in CoCl2 solution were 90% and 75% respectively. The Co (II) removal rate can be increased to nearly 90% by using ethylenediaminetetraacetic acid disodium salt. Increasing the operation pressure or the feeding concentration of Co (II) can also improve the performances of the membranes in this experiment.
Comparison of Advanced Melting Process for HLW Vitrification, Joule-Heated Ceramic-Lined Melter (JHCM) and Cold-Crucible Induction Melter (CCIM)
Authors: Sakai Akira , Koikegami Hajime , Weisenburger Siegfried , Roth Guenther , Kanehira Norio , Komamine Satoshi 
Published: October 2017

High level waste (HLW) originating from reprocessing of spent fuel commercial power reactors contains more than 40 different elements. Vitrification into borosilicate glass at 1100 ∼1200°C is the process of choice. It is routinely used to immobilize the radioactive waste constituents in a chemically stable matrix for a final geological disposal.
Melting process for commercial HLW glasses are variants of two basic designs. (1) The joule-heated ceramic-lined melter (JHCM) originally developed in the United States in 1973 and used in several nuclear sites in the world. (2) The hot-walled induction melter (HWIM), developed in France starting in 1962 and used in France and UK. These technologies, while effective, do pose limitations in waste form compositions and throughput rates. Particularly HLW originating from commercial spent fuel reprocessing usually contains noble metals elements such as ruthenium (Ru), rhodium (Rh), and palladium (Pd) which require special attention when this waste is vitrified.
Recent advances to both of these baseline technologies are beginning to be used with large gains to ensure waste form flexibility, throughputs, and noble metals compatibility. The next generation JHCMs use a steeply sloped bottom and a subsidiary-heating bottom drain to allow these noble metals particles to be effectively flushed from the melter with higher waste loadings. Similar melters are being installed near Guangyuan/Sichuan province, China by German consortium team and being developed for the second K-Facility melter at Rokkasho by Japan Nuclear Fuel Limited (JNFL). As another example the advanced JHCMs will be installed in the Hanford WTP project having large glass pool surface area with rapid bubbling. Significant improvements on induction melters have also been implemented. AREVA recently installed a cold-crucible induction melter (CCIM) in combination with a rotary calciner at La Hague in France. This melter uses radio frequency induction to power the glass melt itself and water cooling of the outer surface maintains a frozen glass shell (skull) as the glass contact material. Because no permanent refractories or embedded electrodes are used, this design allows for high-temperature operation and can tolerate more corrosive melts, and uses a water-cooled, motor-driven mechanical stirrer to comply with noble metals behavior.
This paper highlights some of these advances and suggests potential advantages and disadvantages of these next generation melter technologies comparing advanced JHCM with updated CCIM. In conclusion, these melters have made the technologies of choice for new HLW vitrification projects around the world.
Probabilistic Assessment of Countermeasures for Loss of Ultimate Heat Sink to Spent Fuel Pool
Authors: Fujioka Bumpei , Hirokawa Naoki , Taniguchi Daisuke 
Published: October 2017

In the Fukushima Dai-ichi nuclear power station, Loss of Ultimate Heat Sink (LUHS) was caused by the great east japan earthquake and the subsequent tsunami [1]. It resulted in severe accident in three units. In that time, fuel damage in Spent Fuel Pool (SFP) were prevented by the various countermeasures such as makeup by pump truck and recovery of injection systems /cooling water system.
In the past, Probabilistic Safety Assessment (PSA) has been developed with a focus on the reactor. After the accident, it has been acknowledged that SFP PSA is important to enhance the plant safety.
In this study, probabilistic assessment is performed to suggest countermeasures for LUHS to SFP.
Impacts of Genome-Wide Analyses on Our Understanding of Human Herpesvirus Diversity and Evolution
Authors: Renner Daniel W. , Szpara Moriah L. 
Published: October 2017

ABSTRACT
Until fairly recently, genome-wide evolutionary dynamics and within-host diversity were more commonly examined in the context of small viruses than in the context of large double-stranded DNA viruses such as herpesviruses. The high mutation rates and more compact genomes of RNA viruses have inspired the investigation of population dynamics for these species, and recent data now suggest that herpesviruses might also be considered candidates for population modeling. High-throughput sequencing (HTS) and bioinformatics have expanded our understanding of herpesviruses through genome-wide comparisons of sequence diversity, recombination, allele frequency, and selective pressures. Here we discuss recent data on the mechanisms that generate herpesvirus genomic diversity and underlie the evolution of these virus families. We focus on human herpesviruses, with key insights drawn from veterinary herpesviruses and other large DNA virus families. We consider the impacts of cell culture on herpesvirus genomes and how to accurately describe the viral populations under study. The need for a strong foundation of high-quality genomes is also discussed, since it underlies all secondary genomic analyses such as RNA sequencing (RNA-Seq), chromatin immunoprecipitation, and ribosome profiling. Areas where we foresee future progress, such as the linking of viral genetic differences to phenotypic or clinical outcomes, are highlighted as well.
Mechanisms of HERV-K (HML-2) Transcription during Human Mammary Epithelial Cell Transformation
Authors: Montesion Meagan , Bhardwaj Neeru , Williams Zachary H. , Kuperwasser Charlotte , Coffin John M. 
Published: October 2017

ABSTRACT

Increasing evidence suggests that repetitive elements may play a role in host gene regulation, particularly through the donation of alternative promoters, enhancers, splice sites, and termination signals. Elevated transcript expression of the endogenous retrovirus group HERV-K (HML-2) is seen in many human cancers, although the identities of the individual proviral loci contributing to this expression as well as their mechanisms of activation have been unclear. Using high-throughput next-generation sequencing techniques optimized for the capture of HML-2 expression, we characterized the HML-2 transcriptome and means of activation in an
in vitro
model of human mammary epithelial cell transformation. Our analysis showed significant expression originating from 15 HML-2 full-length proviruses, through four modes of transcription. The majority of expression was in the antisense orientation and from proviruses integrated within introns. We found two instances of long terminal repeat (LTR)-driven provirus transcription but no evidence to suggest that these active 5′ LTRs were influencing nearby host gene expression. Importantly, LTR-driven transcription was restricted to tumorigenic cells, suggesting that LTR promoter activity is dependent upon the transcriptional environment of a malignant cell.

IMPORTANCE
Here, we use an
in vitro
model of human mammary epithelial cell transformation to assess how malignancy-associated shifts in the transcriptional milieu of a cell may impact HML-2 activity. We found 15 proviruses to be significantly expressed through four different mechanisms, with the majority of transcripts being antisense copies of proviruses located within introns. We saw active 5′ LTR use in tumorigenic cells only, suggesting that the cellular environment of a cancer cell is a critical component for induction of LTR promoter activity. These findings have implications for future studies investigating HML-2 as a target for immunotherapy or as a biomarker for disease.
Rice Stripe Tenuivirus Has a Greater Tendency To Use the Prime-and-Realign Mechanism in Transcription of Genomic than in Transcription of Antigenomic Template RNAs
Authors: Liu Xiaojuan , Jin Jing , Qiu Ping , Gao Fangluan , Lin Wenzhong , Xie Guohui , He Simiao , Liu Shunmin , Du Zhenguo , Wu Zujian 
Published: October 2017

ABSTRACT

Most segmented negative-sense RNA viruses employ a process termed cap snatching, during which they snatch capped RNA leaders from host cellular mRNAs and use the snatched leaders as primers for transcription, leading to the synthesis of viral mRNAs with 5′ heterogeneous sequences (HSs). With traditional methods, only a few HSs can be determined, and identification of their donors is difficult. Here, the mRNA 5′ ends of
Rice stripe tenuivirus
(RSV) and
Rice grassy stunt tenuivirus
(RGSV) and those of their host rice were determined by high-throughput sequencing. Millions of tenuiviral HSs were obtained, and a large number of them mapped to the 5′ ends of corresponding host cellular mRNAs. Repeats of the dinucleotide AC, which are complementary to the U
1
G
2
of the tenuiviral template 3′-U
1
G
2
U
3
G
4
UUUCG, were found to be prevalent at the 3′ termini of tenuiviral HSs. Most of these ACs did not match host cellular mRNAs, supporting the idea that tenuiviruses use the prime-and-realign mechanism during cap snatching. We previously reported a greater tendency of RSV than RGSV to use the prime-and-realign mechanism in transcription with leaders cap snatched from a coinfecting reovirus. Besides confirming this observation in natural tenuiviral infections, the data here additionally reveal that RSV has a greater tendency to use this mechanism in transcribing genomic than in transcribing antigenomic templates. The data also suggest that tenuiviruses cap snatch host cellular mRNAs from translation- and photosynthesis-related genes, and capped RNA leaders snatched by tenuiviruses base pair with U
1
/U
3
or G
2
/G
4
of viral templates. These results provide unprecedented insights into the cap-snatching process of tenuiviruses.

IMPORTANCE
Many segmented negative-sense RNA viruses (segmented NSVs) are medically or agriculturally important pathogens. The cap-snatching process is a promising target for the development of antiviral strategies against this group of viruses. However, many details of this process remain poorly characterized. Tenuiviruses constitute a genus of agriculturally important segmented NSVs, several members of which are major viral pathogens of rice. Here, we for the first time adopted a high-throughput sequencing strategy to determine the 5′ heterogeneous sequences (HSs) of tenuiviruses and mapped them to host cellular mRNAs. Besides providing deep insights into the cap snatching of tenuiviruses, the data obtained provide clear evidence to support several previously proposed models regarding cap snatching. Curiously and importantly, the data here reveal that not only different tenuiviruses but also the same tenuivirus synthesizing different mRNAs use the prime-and-realign mechanism with different tendencies during their cap snatching.
Flow Cytometric Detection of PrPScin Neurons and Glial Cells from Prion-Infected Mouse Brains
Authors: Yamasaki Takeshi , Suzuki Akio , Hasebe Rie , Horiuchi Motohiro 
Published: October 2017

ABSTRACTIn prion diseases, an abnormal isoform of prion protein (PrPSc) accumulates in neurons, astrocytes, and microglia in the brains of animals affected by prions. Detailed analyses of PrPSc-positive neurons and glial cells are required to clarify their pathophysiological roles in the disease. Here, we report a novel method for the detection of PrPScin neurons and glial cells from the brains of prion-infected mice by flow cytometry using PrPSc-specific staining with monoclonal antibody (MAb) 132. The combination of PrPScstaining and immunolabeling of neural cell markers clearly distinguished neurons, astrocytes, and microglia that were positive for PrPScfrom those that were PrPScnegative. The flow cytometric analysis of PrPScrevealed the appearance of PrPSc-positive neurons, astrocytes, and microglia at 60 days after intracerebral prion inoculation, suggesting the presence of PrPScin the glial cells, as well as in neurons, from an early stage of infection. Moreover, the kinetic analysis of PrPScrevealed a continuous increase in the proportion of PrPSc-positive cells for all cell types with disease progression. Finally, we applied this method to isolate neurons, astrocytes, and microglia positive for PrPScfrom a prion-infected mouse brain by florescence-activated cell sorting. The method described here enables comprehensive analyses specific to PrPSc-positive neurons, astrocytes, and microglia that will contribute to the understanding of the pathophysiological roles of neurons and glial cells in PrPSc-associated pathogenesis.IMPORTANCEAlthough formation of PrPScin neurons is associated closely with neurodegeneration in prion diseases, the mechanism of neurodegeneration is not understood completely. On the other hand, recent studies proposed the important roles of glial cells in PrPSc-associated pathogenesis, such as the intracerebral spread of PrPScand clearance of PrPScfrom the brain. Despite the great need for detailed analyses of PrPSc-positive neurons and glial cells, methods available for cell type-specific analysis of PrPSchave been limited thus far to microscopic observations. Here, we have established a novel high-throughput method for flow cytometric detection of PrPScin cells with more accurate quantitative performance. By applying this method, we succeeded in isolating PrPSc-positive cells from the prion-infected mouse brains via fluorescence-activated cell sorting. This allows us to perform further detailed analysis specific to PrPSc-positive neurons and glial cells for the clarification of pathological changes in neurons and pathophysiological roles of glial cells.
Murine Hepatitis Virus nsp14 Exoribonuclease Activity Is Required for Resistance to Innate Immunity
Authors: Case James Brett , Li Yize , Elliott Ruth , Lu Xiaotao , Graepel Kevin W. , Sexton Nicole R. , Smith Everett Clinton , Weiss Susan R. , Denison Mark R. 
Published: October 2017

ABSTRACT

Coronaviruses (CoVs) are positive-sense RNA viruses that infect numerous mammalian and avian species and are capable of causing severe and lethal disease in humans. CoVs encode several innate immune antagonists that counteract the host innate immune response to facilitate efficient viral replication. CoV nonstructural protein 14 (nsp14) encodes 3′-to-5′ exoribonuclease activity (ExoN), which performs a proofreading function and is required for high-fidelity replication. Outside of the order
Nidovirales
, arenaviruses are the only RNA viruses that encode an ExoN, which functions to degrade double-stranded RNA (dsRNA) replication intermediates. In this study, we tested the hypothesis that CoV ExoN also functions to antagonize the innate immune response. We demonstrate that viruses lacking ExoN activity [ExoN(−)] are sensitive to cellular pretreatment with interferon beta (IFN-β) in a dose-dependent manner. In addition, ExoN(−) virus replication was attenuated in wild-type bone marrow-derived macrophages (BMMs) and partially restored in interferon alpha/beta receptor-deficient (IFNAR
−/−
) BMMs. ExoN(−) virus replication did not result in IFN-β gene expression, and in the presence of an IFN-β-mediated antiviral state, ExoN(−) viral RNA levels were not substantially reduced relative to those of untreated samples. However, ExoN(−) virus generated from IFN-β-pretreated cells had reduced specific infectivity and decreased relative fitness, suggesting that ExoN(−) virus generated during an antiviral state is less viable to establish a subsequent infection. Overall, our data suggest murine hepatitis virus (MHV) ExoN activity is required for resistance to the innate immune response, and antiviral mechanisms affecting the viral RNA sequence and/or an RNA modification act on viruses lacking ExoN activity.

IMPORTANCE
CoVs encode multiple antagonists that prevent or disrupt an efficient innate immune response. Additionally, no specific antiviral therapies or vaccines currently exist for human CoV infections. Therefore, the study of CoV innate immune antagonists is essential for understanding how CoVs overcome host defenses and to maximize potential therapeutic interventions. Here, we sought to determine the contributions of nsp14 ExoN activity in the induction of and resistance to the innate immune response. We show that viruses lacking nsp14 ExoN activity are more sensitive than wild-type MHV to restriction by exogenous IFN-β and that viruses produced in the presence of an antiviral state are less capable of establishing a subsequent viral infection. Our results support the hypothesis that murine hepatitis virus ExoN activity is required for resistance to the innate immune response.