Nanoscale heat transport through the hetero-interface of SrRuO3 thin films.

A SrRuO3 thin film has been widely used as a metal electrode in electronic devices based on transition metal oxides, and hence it is important to understand its thermal transport properties to minimize a thermal degradation problem during the device operation. Using the time-domain thermoreflectance measurement technique, we investigate the cross-plane thermal conductivity of the SrRuO3 thin films with a thickness variation from 1 µm to 8 nm. We find that the thermal conductivity is reduced from about 6 W m-1 K-1 for the 1 µm thick film to about 1.2 W m-1 K-1 for the 8 nm thick film, and attribute this behavior to the boundary scattering of thermal carriers which originally have the mean free path of about 20 nm in a bulk state. Also, we observe a clear dip behavior of the thermal conductivity in the intermediate thickness around 30 nm which suggests an existence of a strong scattering source other than the film boundary. We explain this result by considering an additional interfacial scattering at the tetragonal-orthorhombic phase boundary which is formed during the strain relaxation with an increase of the film thickness.

Radiating pattern of surge-current-induced THz light in near-field and far-field zone.

We generate the THz wave on the surface of an unbiased GaAs crystal by illuminating femtosecond laser pulses with a 45° incidence angle, and investigate its propagation properties comprehensively both in a near-field and in a far-field zone by performing a knife-edge scan measurement. In the near-field zone, i.e. 540 µm away from the generation point, we found that the beam simply takes a Gaussian shape of which width follows well a behavior predicted by a paraxial wave equation. In the far-field zone, on the other hand, it takes a highly anisotropic shape; whereas the beam profile maintains a Gaussian shape along the normal to the plane of incidence, it takes satellite peak structures along the direction in parallel to the plane of incidence. From the comparison with simulation results obtained by using a dipole radiation model, we demonstrated that this irregular beam pattern is attributed to the combined effect of the position-dependent phase retardation of the THz waves and the diffraction-limited size of the initial beam which lead to the interference of the waves in the far-field zone. Also, we found that this consideration accounting for a crossover of THz beam profile to the anisotropic non-Gaussian beam in the far-field zone can be applied for a comprehensive understanding of several other THz beam profiles obtained previously in different configurations.

Detection of Severe Acute Respiratory Syndrome-Like, Middle East Respiratory Syndrome-Like Bat Coronaviruses and Group H Rotavirus in Faeces of Korean Bats.

Bat species around the world have recently been recognized as major reservoirs of several zoonotic viruses, such as severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV), Nipah virus and Hendra virus. In this study, consensus primer-based reverse transcriptase polymerase chain reactions (RT-PCRs) and high-throughput sequencing were performed to investigate viruses in bat faecal samples collected at 11 natural bat habitat sites from July to December 2015 in Korea. Diverse coronaviruses were first detected in Korean bat faeces, including alphacoronaviruses, SARS-CoV-like and MERS-CoV-like betacoronaviruses. In addition, we identified a novel bat rotavirus belonging to group H rotavirus which has only been described in human and pigs until now. Therefore, our results suggest the need for continuing surveillance and additional virological studies in domestic bat.

Structure and electrochemical performance of Li[Ni(1 -x-y)Co(x)Mn(y)]O2 [0.025 < or = x < or = 0.4, 0.015 < or = y < or = 0.25] as cathodes compound for lithium ion batteries.

Li[Ni(1-x-y)Co(x)Mn(y)]O2 (0.025 < or = x < or = 0.4, 0.015 < or = y < or = 0.25) electrode powders were prepared by a solid-state reaction. The phase purity and R-3m layered structure of the synthesized Li[Ni(1-x-y)Co(x)Mn(y)]O2 materials were confirmed by X-ray diffraction analysis. The particle size of the powder/compounds was decreased with increasing Co and Mn contents to a minimum average particle size of 0.2 approximately 0.3 microm for the LiNi0.35Co0.4Mn0.25O2 powder. A specific capacity of 187 mAh/g was obtained for the LiNi0.35Co0.4Mn0.25O2 electrode with good capacity retention when cycled in the potential region of 3.0-4.6 V with a current density of 20 mA/g at room temperature. Although the structural parameters of the LiNi0.35Co0.4Mn0.25O2 cathode material were similar to those of the LiNil/3CO1/3Mn1/3O2 powder, its specific capacity was higher due to the higher Co contents.

Effect of pretreatment on acid fermentation of organic solid waste.

The effect of various pretreatment methods on acidogenesis of food waste from a cafeteria was investigated. Thermal, enzymatic, and combined thermal-enzymatic batch pretreatment were conducted. Solubilization of food waste in thermal or enzymatic pretreatment increased with either increasing thermal duration or enzyme dosage, respectively. An optimal condition in thermal or enzymatic pretreatment was 60 min of thermal processing or 0.1% (v/v) of enzyme dosage level, respectively, based on volatile suspended solids (VSS) reduction. In the combined pretreatment, increased thermal duration also increased VSS reduction and the solubilization efficiency was higher than that in only enzymatic or thermal pretreatment. The maximum volatile fatty acids (VFAs) production and the highest VFAs fraction in soluble COD in the acid fermentation were achieved with the food waste after 60 min of thermal processing followed by 0.1% (v/v) enzymatic treatment. Increase in VFAs production of the fermenter was over 380% compared to the control fermenter without any pretreatment.

Effect of enzymatic pretreatment on solubilization and volatile fatty acid production in fermentation of food waste.

Food waste can be a valuable carbon source in biological nutrient removal (BNR) systems because of the high C/N and C/P ratio. However, pretreatment is necessary to promote hydrolysis of food waste because of the high concentration of volatile solids associated with organic matter. The influence of the enzymatic pretreatment on acid fermentation of food waste was investigated in this study. Solubilization of particulate matter in food waste was carried out using commercial enzymes. The acidification efficiency and the volatile fatty acid (VFA) production potential of enzymatically pretreated food waste were examined. The highest volatile suspended solid (VSS) reduction was obtained with an enzyme mixture ratio of 1:2:1 for carbohydrase: protease: lipase. An optimum enzyme dosage for solubilization of food waste was 0.1% (V/V) with the enzyme mixture ratio of 1:2:1. In the acid fermentation of enzymatically pretreated food waste, the maximum VFA production and the highest VFA fraction in soluble COD (SCOD) were also achieved at 0.1% (V/N) of total enzyme dosage. Increase in VFA production at this level of enzyme dosage was over 300% compared with the control fermenter. The major form of VFA produced by fermentation was n-butyrate followed by acetate.

A pilot study on accelerated sludge degradation by a high-concentration membrane bioreactor coupled with sludge pretreatment.

A new sludge treatment process combining a high MLSS membrane bioreactor with sludge pretreatment techniques was studied in pilot-scale experiments. The membrane bioreactor (MBR) was adopted for high efficiency aerobic digestion. The combination of alkaline-ozone treatment of the mixed liquor in the MBR reactor accelerated the biodegradation process by enhancing biodegradability of the sludge. The hydraulic retention time (HRT) of the reactor was set as 3.1 days and the DO level was 1 mg/L on average. After 5 months of operation, the accumulative total solids reduction was more than 70%. Removal efficiency of volatile solids and non-volatile solids were 76% and 54%, respectively. It was found that a considerable portion of the non-volatile solids was dissolved into ions and then flushed out with the effluent. Also, about 41% and 28% of T-N and T-P in the raw sludge were removed although no biological nutrient removal process was adopted. The experiment was run smoothly without significant membrane fouling, even at the relatively high levels of MLSS concentration (11,000-25,000 mg/L). It is concluded that the newly proposed process can significantly increase the sludge reduction efficiency with much shorter retention times.

Improvement of the thickening and dewatering characteristics of activated sludge by electroflotation (EF).

The performances of electroflotation (EF) on the thickening of activated sludge were investigated using laboratory scale batch flotation reactors. Four activated sludges including bulking sludges were tested. After 30 minutes of EF operation, 57-84% of sludge volume reduction could be achieved by EF, while only about 1.5-14% could be obtained by gravity thickening for the same period. After thickening the effluent water quality in terms of TCOD, SS, and turbidity was improved by EF operation for all sludge samples. In addition, the EF thickened sludge showed much better dewaterability both in SRF and cake solid content. It is induced that the air bubbles entrapped in the thickened sludge play a key role in the observed dewaterbility improvement.

Determination of nanogram level of VSCs using GC-SCD and an adsorption tube.

A quantitative analytical method was used for detection of low level of volatile sulfur compounds (VSCs) using GC with a sulfur chemiluminescence detector (SCD) in this study. A linear response over the range of 2-90 ngS injected was obtained with a good repeatability or reproducibility. Equimolar response for H2S, DMS, MeSH, and EtSH was obtained by use of SCD and the response of the SCD is nearly equimolar for different sulfur compounds. It was possible to quantify the total VSCs as well as individual VSC using one of the standard VSCs. VSC recovery was measured with respect to some storing methods. An adsorption tube packed with molecular sieve 5A showed almost perfect recovery for both H2S and dimethyl sulfide (DMS) during 6 days at a dark state below 2 degrees. Whereas, with a gas tight pyrex vial or tedlar bag, it was impossible to obtain the recovery of 50% after 6 days. It is strongly recommended to use the adsorption tube for determination of nanogram levels of volatile sulfur compounds and for storing and concentrating VSCs effectively with a minimum experimental error.

Caspase-cleaved TRAF1 negatively regulates the antiapoptotic signals of TRAF2 during TNF-induced cell death.

Tumor necrosis factor (TNF) signaling leads to pleiotropic responses in a wide range of cell types, in part by activating antiapoptotic and proapoptotic pathways. Previous studies have suggested that TNF receptor-associated factor (TRAF) 2 can mediate crucial antiapoptotic signals during TNF stimulation. However, it is unclear how the antiapoptotic signals via TRAF2 in TNF-R1 signaling is regulated. Here we show that TRAF1 is cleaved by caspase-8 into two fragments during apoptosis induced by TNF. Overexpression of the C-terminal cleavage product, TRAF1-c, increased TNF-induced cell death of hybridoma T cells. Importantly, we demonstrate that the cleavage product of TRAF1 coimmunoprecipitates with TRAF2 that is released from the TNF-R1 complex in response to prolonged TNF treatment. These results indicate that caspase-dependent cleavage of TRAF1 generates TRAF1-c fragments that are able to bind TRAF2, and then sequester TRAF2 from the TNF-R1 complex, rendering cells, at least in part, sensitive to TNF.

Molecular studies on bromovirus capsid protein. VII. Selective packaging on BMV RNA4 by specific N-terminal arginine residuals.

An arginine-rich RNA-binding motif (ARM) found at the N-proximal region of Brome mosaic virus (BMV) coat protein (CP) adopts alpha-helical conformation and shares homology with CPs of plant and insect RNA viruses, HIV-Rev and Tat proteins, bacterial antiterminators, and ribosomal splicing factors. The ARM of BMV CP, consisting of amino acids 9 through 21 with six arginine residues, is essential for RNA binding and subsequent packaging. In this study analysis of the alpha-helical contents of wild-type and mutant peptides by circular dichroism spectra identified protein determinants required for such conformation. Electrophoretic mobility-shift assays between viral RNA and BMV CP peptides with either proline or alanine substitutions revealed that the interaction is nonspecific. Expression in vivo of mature full-length BMV CP subunits, having the same substitutions for each arginine within the ARM, derived from biologically active clones was found to be competent to assemble into infectious virions and cause visible symptom phenotypes in whole plants. However, analysis of virion progeny RNA profiles of CP variants and subsequent in vitro reassembly assays between mutant CP and four BMV RNAs unveiled the ability of arginine residues at positions 10, 13, or 14 of the ARM to confer selective packaging of BMV RNA4. Thus, BMV CP contains determinants that specifically interact with RNA4 to ensure selective packaging.

Packaging of tobacco mosaic virus subgenomic RNAs by Brome mosaic virus coat protein exhibits RNA controlled polymorphism.

The coat protein (CP) of icosahedral Brome mosaic virus (BMV) was expressed from a genetically engineered rod-shape Tobacco mosaic virus. Molecular characterization of the progeny recovered from symptomatic plants revealed that BMV CP selectively packaged the three subgenomic RNAs of the hybrid virus into two differently sized icosahedral virus-like particles (VLPs). The smaller VLPs packaged only the two smaller subgenomic RNAs. Additional in vitro reassembly assays with BMV CP subunits and transcripts of hybrid subgenomic RNAs further demonstrated that the ability of BMV capsids to display polymorphism is not dependent on the RNA size alone and appears to be controlled by some other feature(s) of the genetically engineered RNA.

Induction of heme oxygenase-1 in the brains of scrapie-infected mice.

Heme oxygenase-1 (HO-1) is an inducible enzyme that catalyzes the rate-limiting step in the degradation of heme to biliverdin, carbon monoxide and iron, and its expression can be used as a marker for oxidative stress. Oxidative stress has been reported to be associated with neurodegenerative diseases including Alzheimer's disease. It is possible that oxidative stress is also involved in the disease process seen in scrapie, the archetype transmissible spongiform encephalopathy. In this study, we report that HO-1 is significantly increased in the scrapie-infected group compared to an age-matched control group. Immunohistochemistry showed a pronounced increase of immunostaining of this protein in the infected group compared to the minimal amount of staining in the control group. These results support that oxidative stress is closely associated with the pathogenesis of scrapie and that it might contribute to neurodegeneration in this disease.

Molecular studies on bromovirus capsid protein.

Specific interactions are likely to occur between the highly conserved N-proximal arginine-rich motif (ARM) of Brome mosaic virus (BMV) coat protein (CP) and each of three genomic RNAs and a single subgenomic RNA during in vivo encapsidation. To characterize these interactions, three independent deletions were engineered into a biologically active clone of BMV RNA3 (B3) such that the matured CP of each B3 variant precisely lacks either the entire ARM (B3/Delta919) or two consecutive arginine residues (B3/13DeltaDelta14 and B3/18DeltaDelta19) within the ARM. Analysis of virion RNA for each B3 variant recovered from symptomatic leaves of Chenopodium quinoa revealed that the interactions between the N-terminal ARM of BMV CP and each of three genomic RNAs is distinct. Northern blot hybridization of B3Delta919 virion RNA revealed that the deleted ARM region specifically affected the stability of virions containing RNA1. An abundant truncated RNA species recurrently found in the virions of B3Delta919 was identified to be a derivative of genomic RNA1, lacking the 5' 943 nucleotides. Additional Northern blot analysis of virion RNAs from B3/Delta919, B3/13DeltaDelta14, and B3/18DeltaDelta19, and in vitro reassembly assays revealed that the N-terminal ARM region contains crucial amino acids required for RNA4 packaging, independent of genomic RNA3. The significance of these observations in relation to Bromovirus CP-RNA interactions during virion assembly is discussed.

Identification of sugarcane striate mosaic-associated virus by partial characterization of its double-stranded RNA.

ABSTRACT Sugarcane striate mosaic (ScSM)-affected sugarcane leaves contain a disease-associated 9-kilobase (kb) double-stranded RNA (dsRNA), usually together with 6- and 2.6-kb dsRNAs. The purified 9-kb dsRNA was amplified by the randomly primed polymerase chain reaction (PCR) and cloned. The nucleotide sequences of three separate regions, representing about 2.55 kb (28%) of the dsRNA sequence, were found to have significant similarities to viruses in the genera Capillo-, Carla-, Fovea-, Potex-, Poty-, Tricho-, and Tymovirus. Greatest overall similarity was found to apple stem pitting virus, with less similarity to blueberry scorch virus and potato virus M. A standard virus purification procedure was used to identify slightly flexuous filamentous particles that copurified with the disease-associated RNA. Particle modal lengths were approximately 950 and 1,900 nm with a diameter of 15 nm. Preparations contained a 51-kDa putative capsid protein and a 9-kb single-stranded RNA with a probable 3' polyadenylate tract. These ScSM-associated virus particles differ physically from viruses in existing genera because of their relative rigidity, length, and putative coat protein size. Reverse-transcription PCR with a primer pair designed from the sequenced segments amplified a 820-base pair fragment from ScSM-affected but not healthy sugarcane plants.

Molecular studies on bromovirus capsid protein.

Brome mosaic bromovirus (BMV) and cucumber mosaic cucumovirus (CMV) are structurally and genetically very similar. The specificity of the BMV and CMV coat proteins (CPs) during in vivo encapsidation was studied using two RNA3 chimera in which the respective CP genes were exchanged. The replicative competence of each chimera was analyzed in Nicotiana benthamiana protoplasts, and their ability to cause infections was examined in two common permissive hosts, Chenopodium quinoa and N. benthamiana. Each RNA3 chimera replicated to near wild-type (wt) levels and synthesized CPs of expected parental origin when co-inoculated with their respective genomic wt RNAs 1 and 2. However, inoculum containing each chimera was noninfectious in the common permissive hosts tested. Encapsidation assays in N. benthamiana protoplasts revealed that CMV CP expressed from chimeric BMV RNA3 was capable of packaging heterologous BMV RNA, however, at a lower efficiency than parental BMV CP. By contrast, BMV CP expressed from chimeric CMV RNA3 was unable to package heterologous CMV RNA. These observations demonstrate that BMV CP, but not CMV CP, exhibits a high degree of specificity during in vivo packaging. The reasons for the noninfectious nature of each chimera in the host plants tested and factors likely to affect encapsidation in vivo are discussed.