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U7 snRNP is a multi-subunit endonuclease required for 3’ end processing of metazoan replication-dependent histone pre-mRNAs. In contrast to the spliceosomal snRNPs, U7 snRNP lacks the Sm subunits D1 and D2 and instead contains two related proteins, Lsm10 and Lsm11. The remaining five subunits of the U7 heptameric Sm ring, SmE, F, G, B and D3, are shared with the spliceosomal snRNPs. The pathway that assembles the unique ring of U7 snRNP is unknown. Here, we show that a heterodimer of Lsm10 and Lsm11 tightly interacts with the methylosome, a complex of the arginine methyltransferase PRMT5, MEP50 and pICln known to methylate arginines in the C-terminal regions of the Sm proteins B, D1 and D3 during the spliceosomal Sm ring assembly. Both biochemical and Cryo-EM structural studies demonstrate that the interaction is mediated by PRMT5, which binds and methylates two arginine residues in the N-terminal region of Lsm11. Surprisingly, PRMT5 also methylates an N-terminal arginine in SmE, a subunit that does not undergo this type of modification during the biogenesis of the spliceosomal snRNPs. An intriguing possibility is that the unique methylation pattern of Lsm11 and SmE plays a vital role in the assembly of the U7 snRNP.

Human cleavage and polyadenylation specificity factor (CPSF)73 (also known as CPSF3) is the endoribonuclease that catalyzes the cleavage reaction for the 3′-end processing of pre-mRNAs. The active site of CPSF73 is located at the interface between a metallo-β-lactamase domain and a β-CASP domain. Two metal ions are coordinated by conserved residues, five His and two Asp, in the active site, and they are critical for the nuclease reaction. The metal ions have long been thought to be zinc ions, but their exact identity has not been examined. Here we present evidence from inductively coupled plasma mass spectrometry and X-ray diffraction analyses that a mixture of metal ions, including Fe, Zn, and Mn, is present in the active site of CPSF73. The abundance of the various metal ions is different in samples prepared from different expression hosts. Zinc is present at less than 20% abundance in a sample expressed in insect cells, but the sample is active in cleaving a pre-mRNA substrate in a reconstituted canonical 3′-end processing machinery. Zinc is present at 75% abundance in a sample expressed in human cells, which has comparable endonuclease activity. We also observe a mixture of metal ions in the active site of the CPSF73 homolog INTS11, the endonuclease for Integrator. Taken together, our results provide further insights into the role of metal ions in the activity of CPSF73 and INTS11 for RNA 3′-end processing.

Integrator has critical roles in noncoding RNA 3′-end processing as well as transcription attenuation of selected mRNAs. IntS11 is the endonuclease for RNA cleavage, as a part of the IntS4-IntS9-IntS11 complex (Integrator cleavage module, ICM). Our structure of the Drosophila ICM, determined by cryo-electron microscopy at 2.74 Å resolution, unexpectedly revealed the stable association of an inositol hexakisphosphate (IP6) molecule. The binding site is located in a highly electropositive pocket at an interface among all three subunits of ICM, 55 Å away from the IntS11 active site and generally conserved in other ICMs. IP6 binding is also confirmed in human ICM. Mutations of residues in this binding site or disruption of IP6 biosynthesis significantly reduced Integrator assembly and activity in snRNA 3′-end processing. Our structural and functional studies reveal that Integrator is subject to intricate cellular control and IP6 is a critical regulator of Integrator assembly and function in Drosophila, humans, and likely other organisms.

Determining the precursor/product ion pair and optimal collision energy are the critical steps for developing a multiple reaction monitoring (MRM) assay using triple quadruple mass spectrometer for protein quantitation. In this study, a platform consisting of stable isotope dimethyl labeling coupled with triple-quadruple mass spectrometer was used to quantify the protein components of the influenza vaccines. Dimethyl labeling of both the peptide N-termini and the ϵ-amino group of lysine residues was achieved by reductive amination using formaldehyde and sodium cyanoborohydrate. Dimethylated peptides are known to exhibit dominant a1 ions under gas phase fragmentation in a mass spectrometer. These a1 ions can be predicted from the peptide N-terminal amino acids, and their signals do not vary significantly across a wide range of collision energies, which facilitates the determination of MRM transition settings for multiple protein targets. The intrinsic a1 ions provide sensitivity for acquiring MRM peaks that is superior to that of the typical b/y ions used for native peptides, and they also provided good linearity (R2 ≥ 0.99) at the detected concentration range for each peptide. These features allow for the simultaneous quantification of hemagglutinin and neuraminidase in vaccines derived from either embryo eggs or cell cultivation. Moreover, the low abundant ovalbumin residue originated from the manufacturing process can also be determined. The results demonstrate that the stable isotope dimethyl labeling coupled with MRM Mass spectrometry screening of a1 ions (i.e., SIDa-MS) can be used as a high-throughput platform for multiple protein quantification of vaccine products.

Two-dimensional (2D) semiconductors play a crucial role in high-efficiency photocatalysts because of their high surface-to-volume ratio. The surface property is a key part of photocatalysis. In this work, the enhanced photocatalytic behavior of the layered ReS2 with optical polarization along the Re4 nano-diamond-chain (DC) direction (b axis) has been demonstrated. The unpolarized photoconductivity (PC) response of ReS2 with an applied bias along the b axis is approximately 1 order higher than that of the applied bias perpendicular to the b axis. The polarization-dependent PC spectra of E ∥ b also reveal a higher photoresponsivity with respect to those measured along the E ⊥ b polarization for the layered ReS2. This result indicates that stronger polarization dipoles as well as a larger amount of photogenerated carriers and surface states can contribute to the C-plane ReS2 under the illumination of E ∥ b polarized photons. With the special axial effect, the layered ReS2 2D photocatalyst shows much faster ...

A wide gap semiconductor material has attracted attention as a heterophotocatalyst because of its light harvesting nature to be used in alternative energy production for the next generation. We, herein, grow and synthesize ZnS(1–x)Ox series compounds using the chemical vapor transport (CVT) method with I2 serving as the transport agent. Different crystals, such as undoped ZnS and oxygen-doped ZnS0.94O0.06 and ZnS0.88O0.12, revealed different bright palette emissions that were presented in photoluminescence spectra in our previous report. To study the electron–hole pair interaction of this sample series, the near-band-edge transitions of the sample series were characterized in detail by photoconductivity (PC) experiments. Additional results from surface photovoltage (SPV) spectra also detected the surface and defect-edge transitions from the higher oxygen-doped ZnS crystals. PC measurement results showed a red-shift in the bandgap with increasing incorporation of oxygen on ZnS. Consequently, the samples were subjected to photoirradiation by xenon lamp for the degradation of methylene blue (MNB) by acting as heterophotocatalysts. Undoped ZnS emerged as the best photocatalyst candidate with the fastest rate constant value of 0.0277 min–1. In cubic {111} ZnS [{111} c-ZnS], the polarized Zn+ → S– ions may play a vital role as a photocatalyst because of their strong electron–hole polarization, which leads to the mechanism for degradation of the MNB solution.

Flexible optoelectronics devices play an important role for technological applications of 2D materials because of their bendable, flexible and extended two-dimensional surfaces. In this work, light emission properties of layered gallium selenide (GaSe) crystals with different curvatures have been investigated using bending photoluminescence (BPL) experiments in the curvature range between R−1 = 0.00 m−1 (flat condition) and R−1 = 30.28 m−1. A bendable and rotated sample holder was designed to control the curvature (strain) of the layered sample under upward bending uniformly. The curvature-dependent BPL results clearly show that both bandgaps and BPL intensities of the GaSe are curvature dependent with respect to the bending-radius change. The main emission peak (bandgap) is 2.005 eV for flat GaSe, and is 1.986 eV for the bending GaSe with a curvature of 30.28 m−1 (the maximum bending conditions in this experiment). An obvious redshift (i.e. energy reduction) for the GaSe BPL peak was detected owing to the c-plane lattice expansion by upward bending. The intensities of the corresponding BPL peaks also show an increase with increasing curvature. The correlations between BPL peak intensity, shiny area and bond-angle widening of the bent GaSe under laser excitation have been discussed. The lattice constant versus emission energies of the bending GaSe was also analyzed. An estimated lattice constant vs. bandgap relation was present for further application of the layered GaSe in bendable flexible light-emission devices.

Severe acute respiratory syndrome coronavirus (SARS-CoV) emerged in southern China in late 2002 and caused a global outbreak with a fatality rate around 10% in 2003. Ten years later, a second highly pathogenic human CoV, MERS-CoV, emerged in the Middle East and has spread to other countries in Europe, North Africa, North America and Asia. As of November 2017, MERS-CoV had infected at least 2102 people with a fatality rate of about 35% globally, and hence there is an urgent need to identify antiviral drugs that are active against MERS-CoV. Here we show that a clinically available alcohol-aversive drug, disulfiram, can inhibit the papain-like proteases (PLpros) of MERS-CoV and SARS-CoV. Our findings suggest that disulfiram acts as an allosteric inhibitor of MERS-CoV PLpro but as a competitive (or mixed) inhibitor of SARS-CoV PLpro. The phenomenon of slow-binding inhibition and the irrecoverability of enzyme activity after removing unbound disulfiram indicate covalent inactivation of SARS-CoV PLpro by disulfiram, while synergistic inhibition of MERS-CoV PLpro by disulfiram and 6-thioguanine or mycophenolic acid implies the potential for combination treatments using these three clinically available drugs., Highlights • Disulfiram, a drug for use in alcohol aversion therapy, can inhibit the papain-like proteases of MERS-CoV and SARS-CoV. • Disulfiram is a noncompetitive inhibitor of MERS-CoV papain-like protease. • Disulfiram, 6-thioguanine and mycophenolic acid can synergistically inhibit MERS-CoV papain-like protease. • Disulfiram is a competitive inhibitor of SARS-CoV papain-like protease. • Disulfiram is a slow-binding inhibitor that forms a covalent adduct at the active site of SARS-CoV papain-like protease.

Single crystals of oxygen-incorporated ZnS (i.e., ZnS(1–x)Ox series) are environment-friendly wide-band-gap semiconductors available for light-emitting devices and solar cell use. The series of materials has considerable potential for use in visible ultraviolet areas with flexibility for palette emissions. In this study, we grow oxygen-incorporated ZnS series crystals by chemical vapor transport method with iodine (I2) as the transport agent. Three different oxygen-incorporated crystals of undoped ZnS, ZnS0.94O0.06, and ZnS0.88O0.12 are studied. Through structural studies, ZnS doped with oxygen crystallizes in the main sphalerite phase and a little wurtzite structure. The lattice constants of the major cubic phase are determined to be a = 5.43 A (ZnS), 5.41 A (ZnS0.94O0.06), and 5.39 A (ZnS0.88O0.12). Three band-edge excitonic transitions are simultaneously detected by thermoreflectance measurement for the ZnS, ZnS0.94O0.06, and ZnS0.88O0.12 series samples. The energy positions of the band-edge transition...

We applied a thermal-desorption gas-chromatograph mass-spectrometer (TD-GC&ndash, MS) system to identify the marker volatile organic compounds (VOCs) in the aroma of red wine. After obtaining the marker VOC, we utilized surface acoustic waves (SAWs) to develop a highly sensitive sensing system as 'electronic nose' to detect these marker VOC. The SAW chips were fabricated on a LiNbO3 substrate with a lithographic process. We coated sensing polymers on the sensing area to adsorb the marker VOC in a sample gas. The adsorption of the marker VOC altered the velocity of the SAW according to a mass-loading effect, causing a frequency decrease. This experiment was conducted with wines of three grape varieties&mdash, cabernet sauvignon, merlot and black queen. According to the results of TD-GC&ndash, MS, the King brand of red wine is likely to have unique VOC, which are 2-pentanone, dimethyl disulfide, 2-methylpropyl acetate and 2-pentanol, Blue Nun-1 probably has a special VOC such as 2,3-butanedione. We hence used a SAW sensor array to detect the aroma of red wines and to distinguish their components by their frequency shift. The results show that the use of polyvinyl butyral (PVB) as a detecting material can distinguish Blue Nun-2 from the others and the use of polyvinyl alcohol (PVA) can distinguish King from the others. We conducted random tests to prove the accuracy and the reliability of our SAW sensors.

We report on optical examination of structural properties of cubic-In2O3 (c-In2O3) degenerate-semiconducting-oxide thin-film nanostructures grown on Si (100) substrates using vapor transport method driven with vapor–liquid–solid mechanism. Two different types of dense (A) and loose (B) c-In2O3 thin-film nanorods have been, respectively, characterized by photoluminescence (PL), time-resolved photoluminescence (TRPL), thermoreflectance (TR), and Hall and resistivity measurements. Strong excitonic emissions detected from the PL results of the A and B samples identify the high-crystalline quality of the arrow-type c-In2O3 nanorods. Theoretical modeling fits on the TRPL results of the A and B samples characterize and identify defect mechanisms of the nanostructured thin films. Near-band-edge and above-band-edge transitions such as excitons, direct band gap, and Burstein–Moss shift (above direct gap) in the degenerate A and B c-In2O3 have also been detected by TR measurement. Field-emission scanning electron mi...

Crystal growth, characterization, and sensing application of In 2 S 3 and Ga 2 S 3 are demonstrated herein. Single crystals of In 2 S 3 and Ga 2 S 3 were grown by chemical vapor transport method using ICl 3 as the transport agent. The as-grown In 2 S 3 crystals essentially show dark red and Ga 2 S 3 displays transparent and light-yellow colored. X-ray diffraction measurements show tetragonal phase of the as-grown In 2 S 3 crystals while Ga 2 S 3 crystallizes in the monoclinic structure. The optical band edges of In 2 S 3 and Ga 2 S 3 were characterized by absorption and thermoreflectance measurements. The optical band gaps of In 2 S 3 and Ga 2 S 3 are 1.935 eV and 3.052 eV, respectively. The direct gaps of In 2 S 3 and Ga 2 S 3 lie in between red to violet visible region. Photoluminescence (PL) experiments characterize defect and surface-state emissions of the In 2 S 3 and Ga 2 S 3 crystals. The In 2 S 3 can easily form surface oxide in environmental air with an In 2 O 3 growth rate of ∼100 nm/day (i.e. for oxygen sensing). The PL intensity of the In 2 O 3 formed on In 2 S 3 may be a sensing index for oxygen content detection. Besides, Ga 2 S 3 may emit a broadened visible white light (near band edge) due to the existence of intrinsic defects inside the crystal. The Ga 2 S 3 crystal also displays a high-sensitivity photoconductivity change illuminated by a 405 nm laser. According to the experimental results, In 2 S 3 can be an oxygen sensor with the formation of surface oxide (i.e. In 2 O 3 ), while Ga 2 S 3 may possess potential capability in fabrication of blue to UV photodetector.

Native disulfide formation is crucial to the process of disulfide-rich protein folding in vitro. As such, analysis of the disulfide bonds can be used to track the process of the folding reaction, however, the diverse structural isomers interfere with characterization due to the non-native disulfide linkages. Previously, a mass spectrometry (MS) based platform coupled with peptide demethylation and an automatic disulfide bond searching engine demonstrated the potential to screen disulfide-linked peptides for the unambiguous assignment of paired cysteine residues of toxin components in cobra venom. The developed MS-based platform was evaluated to analyze the disulfide bonds of structural isomers during the folding reaction of synthetic cardiotoxin A3 polypeptide (syn-CTX A3), an important medical component in cobra venom. Through application of this work flow, a total of 13 disulfide-linked peptides were repeatedly identified across the folding reaction, and two of them were found to contain cysteine pairings, like those found in native CTX A3. Quantitative analysis of these disulfide-linked peptides showed the occurrence of a progressive disulfide rearrangement that generates a native disulfide bond pattern on syn-CTX A3 folded protein. The formation of these syn-CTX A3 folded protein reaches a steady level in the late stage of the folding reaction. Biophysical and cell-based assays showed that the collected syn-CTX A3 folded protein have a &beta, sheet secondary structure and cytotoxic activity similar to that of native CTX A3. In addition, the immunization of the syn-CTX A3 folded proteins could induce neutralization antibodies against the cytotoxic activity of native CTX A3. In contrast, these structure activities were poorly observed in the other folded isomers with non-native disulfide bonds. The study highlights the ability of the developed MS platform to assay isomers with heterogeneous disulfide bonds, providing insight into the folding mechanism of the bioactive protein generation.

ZnO nanorods (NRs) incorporating a graphene layer were fabricated on silicon substrates. The graphene layer was placed on top and bottom of ZnO to form graphene/ZnO NRs/Si and ZnO NRs/graphene/Si nanocomposites. To characterize these nanocomposites, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction were used, as well as contact angle measurements to study hydrophilic properties. Finally, OD600 bacterial growth tests were performed to investigate the bacterial suppression capabilities. Results indicate that the ZnO NRs/graphene/Si nanocomposite exhibits the strongest bacterial suppression capability among the studied nanostructures.

ZnS is an environmentally friendly wide-band-gap semiconductor possessing a direct gap larger than ZnO, which makes it more promising for application in ultraviolet (UV) optoelectronics and solar-energy conversion applications. However, highly crystalline ZnS is usually obtained by elegant epitaxial growth, such as with pulsed laser vaporization, molecular beam epitaxy, and metal–organic chemical vapour deposition, in a thin-film form. A high-quality ZnS substrate crystal has been rarely achieved to date. Herein, we demonstrate a high-grade cubic ZnS (c-ZnS) substrate crystal with a longer range order grown by a chemical vapour transport (CVT) method. Photoluminescence (PL), transmittance, contactless electroreflectance (CER), and transmission electron microscopy were performed for qualification of the c-ZnS substrate. The transparency of the c-ZnS substrate crystal (∼0.6 mm thick) was about 81% at λ = 400 nm and 92% at λ = 600 nm. Strong and complete series excitonic emissions were detected from the ZnS substrate crystal by PL, indicating the high crystallinity of the CVT-grown ZnS. Band-edge free-exciton emission of the ZnS substrate showed an intense emission around 3.68 eV at 300 K. The temperature dependences of the band-edge excitonic emissions from 10 to 300 K were analyzed and are herein discussed in terms of sustaining the high crystalline quality of the c-ZnS substrate. An initially-formed Cu/ZnS Schottky solar cell was also tested using the c-ZnS substrate. Under the illumination of a 325 nm laser (i.e. a power density of P ∼ 48 mW cm−2), a significant photovoltage of ∼0.6 V could be generated from the original Cu/ZnS Schottky solar cell.

High-k NdTaO4 dielectrics annealed with various temperatures were first deposited on polycrystalline silicon substrates. Material and electrical characterizations were performed. To examine the crystalline structures, X-ray diffraction patterns were analyzed. Electrical measurements including current–voltage characteristics, constant current stress, and the Weibull plots show that annealing could enhance the breakdown voltages, lower the trapping rate, and strengthen the reliability. Results indicate that annealing at 900 °C may optimize the dielectric performance. This dielectric shows promise for future gate material or flash memory integrated with current NdTaO4-based optical devices.

In this study, CeO2 was used as a trapping layer in metal oxide high-K-oxide-Si (MOHOS)-type memory devices. This trapping layer underwent annealing to enhance memory performance. Multiple material analyses indicate that annealing enables enhanced crystallization and suppresses silicate formation. MOHOS-type flash memory devices incorporating a CeO2 charge trapping layer annealed at 950 °C exhibited a large memory window of 4.7 V, as well as a fast program and erase speed. Our research indicates that MOHOS-type memory devices utilizing CeO2 show great promise for future industrial flash memory applications.

ZnO nanorods were deposited on silicon substrate using sol-gel hydrothermal methods. The seed layer was first grown by sol-gel methods and then annealed at temperatures of 300ºC, 400ºC, 500ºC and 600ºC. Multiple material and optical analyses including field-emission scanning electron microscope, energy dispersive X-ray spectroscopy, X-ray diffraction, photoluminescence spectra, and Raman spectra were conducted to examine the growth orientation and material properties. Results indicate that the ZnO nanorods annealed at a proper temperature of 400ºC could enhance orientation and material quality.

Layered-type α- and γ-In 2 Se 3 crystals were simultaneously grown by chemical vapor transport (CVT) method using ICl 3 as the transport agent. The crystalline state, surface state, and structural polytype of the as-grown In 2 Se 3 were observed by high-resolution transmission electron microscopy (HRTEM). The direct band edges of α- and γ-In 2 Se 3 were evaluated by thermoreflectance (TR) measurements. For α-In 2 Se 3 , a surface oxidation layer α-In 2 Se 3−3 x O 3 x (0 ≤ x ≤ 1) can easily form on the crystal face in environmental air by oxygen detection (∼250 nm/day). The surface formation oxide can be easily removed by laser treatment ( λ = 266 nm, P = 60 mW) and the oxygen detection can be repeated again. For γ-In 2 Se 3 , the HRTEM and Raman measurements reveal amorphous and polycrystalline state existing in the as-grown crystals. The amorphous effect renders erasable optical-memory switching of γ ↔ α inter-phase transition occurred inside the γ-In 2 Se 3 layer with laser heating treatment. The phase transition of In 2 Se 3 is fast and easily by using the laser treatment. The phase transformation of γ ↔ α was verified by Raman and TR measurements. The optical-memory switching and oxygen detection behavior for the as-grown γ- and α-phase In 2 Se 3 are demonstrated herein.

Highlights • 6-Mercaptopurine and 6-thioguanine are competitive inhibitors of SARS-CoV and MERS-CoV papain-like proteases. • Mycophenolic acid can noncompetitively inhibit papain-like protease of MERS-CoV, while cannot inhibit that of SARS-CoV. • 6-Mercaptopurine/6-thioguanine and mycophenolic acid synergistically inhibit MERS-CoV papain-like protease. • The three drugs with inhibitory effect for MERS-CoV papain-like protease can be used as lead compounds for drug development., Middle East respiratory syndrome coronavirus (MERS-CoV) is a new highly pathogenic human coronaviruses that emerged in Jeddah and Saudi Arabia and has quickly spread to other countries in Middle East, Europe and North Africa since 2012. Up to 17 December 2014, it has infected at least 938 people with a fatality rate of about 36% globally. This has resulted in an urgent need to identify antiviral drugs that are active against MERS-CoV. The papain-like protease (PLpro) of MERS-CoV represents an important antiviral target as it is not only essential for viral maturation, but also antagonizes interferon stimulation of the host via its deubiquitination activity. Here, we report the discovery that two SARS-CoV PLpro inhibitors, 6-mercaptopurine (6MP) and 6-thioguanine (6TG), as well as the immunosuppressive drug mycophenolic acid, are able to inhibit MERS-CoV PLpro. Their inhibition mechanisms and mutually binding synergistic effect were also investigated. Our results identify for the first time three inhibitors targeting MERS-CoV PLpro and these can now be used as lead compounds for further antiviral drug development.

In this study, we address process how the ZnO nanorods were deposited on GaN substrates with spin-coating by using the hydro-thermal methods. After ZnO was spin coated, the samples were annealed with different temperatures to incorporate with Au nano particles. Multiple material analyses, such as the field emission scanning electron microscopy (FESEM), the energy dispersive X-ray spectroscopy (EDX) and the X-ray diffraction (XRD) analyses were carried out to characterize the Au nanoparticles/ZnO nanorods/GaN nanocomposites.

ReS

Multilayer InSe with a thickness above ~20 nm is a direct semiconductor proposed for solar-energy conversion and to use in flexible optoelectronics. We demonstrate herein a superior 1000-nm light emission and absorption capability of two-dimensional (2D) multilayer InSe studied by photoluminescence (PL) and photoconductivity (PC) experiments. Layered crystals of InSe have been grown by chemical vapor transport method using ICl3 as a transport agent. Polarized Raman measurement confirmed 2 H e crystalline phase of the as-grown crystals. For 2D flexible applications, the bending photoluminescence (BPL) result of InSe (t ≈ 30 nm) showed an enhancement in light intensity with respect to that of the flat PL condition. It might be because the cylinder surface area under bending (convex) is larger than that of the flat surface under the same laser excitation condition. Besides, the luminescence efficiency of BPL is also enhanced owing to the widening of emission solid angle of each Se-In-In-Se unit in the InSe as compared to that of the flat PL condition. The emission wavelength is about 1000 nm at room temperature. Furthermore, for the PC study, photoresponsivity spectrum of a Ag-InSe-Ag multilayer photoconductor demonstrates a prominent peak absorption at 1.1 ~ 1.3 eV, matching well with the direct-free-exciton energy of the multilayer InSe. All the experimental results demonstrate that 2D multilayer InSe is a promising 1000 nm light emitter and absorber available for potential optoelectronics applications.

In order to investigate the filterability of artificial fiber, salts were added to the fiber for particulate removal. In addition, nanofibers were prepared for particle filtration efficiency assessment, and Nylon 6 nanofibers were prepared by electrospinning. Scanning electron microscopy (SEM) was used for analyzing the fiber characteristics. Furthermore, the single-factor experimental method was used to study the optimal material preparation method and operating parameters, including content of different salts (NaCl and KCl), with Nylon 6 nanofibers for particle removal. The particle removal efficiency of pure Nylon 6 nanofibers was about 95%. The removal efficiencies of Nylon 6 nanofibers containing NaCl and KCl were 99% and 98%, respectively. It was found that the removal efficiency of nanofibers was decreased with increasing content of salts in Nylon 6 nanofibers.

Resolving failure origins of AlGaN/GaN light emitting diodes (LED) has received intensive study recently. In this study, formation of GaCO3 caused by carbon contamination may result in deformation of the electrode near the surface and degrade the device. The electrochemical reactions may cause device damages. Degradation in electrical properties is observed in I-V characteristics. Forward-bias and reverse-bias EL images are used to trace the damaged areas. Furthermore, focus ion beam (FIB), scanning electron microscope (SEM), energy dispersive X-ray diffraction (EDX) are applied to examine the damaged areas. Results indicate that formation of GaCO3 may deform the electrode, generate the reverse-bias EL and cause the degradation.

Pyruvate carboxylase (PC) has important roles in metabolism and is crucial for virulence for some pathogenic bacteria. PC contains biotin carboxylase (BC), carboxyltransferase (CT) and biotin carboxyl carrier protein (BCCP) components. It is a single-chain enzyme in eukaryotes and most bacteria, and functions as a 500 kD homo-tetramer. In contrast, PC is a two-subunit enzyme in a collection of Gram-negative bacteria, with the α subunit containing the BC and the β subunit the CT and BCCP domains, and it is believed that the holoenzyme has α4β4 stoichiometry. We report here the crystal structures of a two-subunit PC from Methylobacillus flagellatus. Surprisingly, our structures reveal an α2β4 stoichiometry, and the overall architecture of the holoenzyme is strikingly different from that of the homo-tetrameric PCs. Biochemical and mutagenesis studies confirm the stoichiometry and other structural observations. Our functional studies in Pseudomonas aeruginosa show that its two-subunit PC is important for colony morphogenesis., Pyruvate carboxylases are homotetrameric enzymes in eukaryotes and most bacteria. Here, the authors report the structure of an unusual two-subunit form of the enzyme from the Gram-negative bacterium Methylobacillus flagellates, revealing an unexpected α2β4 stoichiometry.

Crystallins are found widely in animal lenses and have important functions due to their refractive properties. In the coleoid cephalopods, a lens with a graded refractive index provides good vision and is required for survival. Cephalopod S-crystallin is thought to have evolved from glutathione S-transferase (GST) with various homologs differentially expressed in the lens. However, there is no direct structural information that helps to delineate the mechanisms by which S-crystallin could have evolved. Here we report the structural and biochemical characterization of novel S-crystallin-glutathione complex. The 2.35-Å crystal structure of a S-crystallin mutant from Octopus vulgaris reveals an active-site architecture that is different from that of GST. S-crystallin has a preference for glutathione binding, although almost lost its GST enzymatic activity. We’ve also identified four historical mutations that are able to produce a “GST-like” S-crystallin that has regained activity. This protein recapitulates the evolution of S-crystallin from GST. Protein stability studies suggest that S-crystallin is stabilized by glutathione binding to prevent its aggregation; this contrasts with GST-σ, which do not possess this protection. We suggest that a tradeoff between enzyme activity and the stability of the lens protein might have been one of the major driving force behind lens evolution.

A live enterovirus 71 (EV71) isolate designated, EV71/E59, with genotype B4 produced in Vero cells and purified over a sucrose gradient was used as the immunogen to generate EV71-specific murine monoclonal antibodies. Four hybridoma clones derived from the fusion of splenocytes of EV71/E59-preimmunized BALB/c (H-2(d)) mice and the NS-1 myeloma cells that exhibit stable growth were selected for detailed characterization. The proof that the hybridomas produced are indeed true independent clones was based on the obervations that they expressed different complementarity-determining regions (CDRs) in their κ light chain genes. Purified ascitic fluids produced by the individual clones reacted against the viral capsid protein, VP1, in Western blot; and recognized distinct sites of a common epitope localized at the C-terminal half of VP1. Each of the monoclonal antibodies exhibited potent neutralizing activities against the immunizing virus strain, as well as two other isolates namely, N0781-TW-01, and N2838, of subgenogroups B4 and B5, respectively, that were found commonly in recent outbreaks in Taiwan. It was also observed the monoclonal antibodies acted cooperatively in neutralizing the EV71/E59 virus.

Multilayer InSe with a thickness above 20 nm is a direct semiconductor for flexible-optoelectronics use. We show a superior 1000-nm light emission and absorption capability of 2D multilayer InSe studied by photoluminescence and photoconductivity herein.

Three peptides, D1 (amino acid residues 175–201), D2 (a.a. 434–467), and TM (a.a. 1128–1159), corresponding to the spike protein (S) of severe acute respiratory syndrome corona virus (SARS CoV) were synthesized and their immunological functions were investigated in three different animals models (mice, guinea pigs, and rabbits). The peptides mixture formulated either with Freund’s adjuvant or synthetic adjuvant Montanide ISA-51/oligodeoxy nucleotide CpG (ISA/CpG) could elicit antisera in immunized animals which were capable of inhibiting SARS/HIV pseudovirus entry into HepG2 cells. The neutralizing epitopes were identified using peptides to block the neutralizing effect of guinea pig antisera. The major neutralizing epitope was located on the D2 peptide, and the amino acid residue was fine mapped to 434–453. In BALB/c mice T-cell proliferation assay revealed that only D2 peptide contained T-cell epitope, the sequence of which corresponded to amino acid residue 434–448. The ISA/CpG formulation generated anti-D2 IgG titer comparable to those obtained from Freund’s adjuvant formulation, but generated fewer antibodies against D1 or TM peptides. The highly immunogenic D2 peptide contains both neutralizing and Th cell epitopes. These results suggest that synthetic peptide D2 would be useful as a component of SARS vaccine candidates.

Hand-foot-mouth diseases (HFMD) caused by enterovirus 71 (EV71) and coxsackievirus 16 (CVA16) in children have now become a severe public health issue in the Asian-Pacific region. Recently we have successfully developed transgenic mice expressing human scavenger receptor class B member 2 (hSCARB2, a receptor of EV71 and CVA16) as an animal model for evaluating the pathogenesis of enterovirus infections. In this study, hSCARB2-transgenic mice were used to investigate the efficacy conferred by a previously described EV71 neutralizing antibody, N3. A single injection of N3 effectively inhibited the HFMD-like skin scurfs in mice pre-infected with clinical isolate of EV71 E59 (B4 genotype) or prevented severe limb paralysis and death in mice pre-inoculated with 5746 (C2 genotype). This protection was correlated with remarkable reduction of viral loads in the brain, spinal cord and limb muscles. Accumulated viral loads and the associated pro-inflammatory cytokines were all reduced. The protective efficacy of N3 was not observed in animals challenged with CVA16. This could be due to dissimilarity sequences of the neutralizing epitope found in CVA16. These results indicate N3 could be useful in treating severe EV71 infections and the hSCARB2-transgenic mouse could be used to evaluate the protective efficacy of potential anti-enterovirus agent candidates.

Identification of the cytotoxic T lymphocyte (CTL) epitopes of tumor antigens is important for effective immunotherapy. We report that a combination of epitope prediction, enzyme-linked immunosorbent assay (ELISA)-based epitope-HLA complex formation, and DNA immunization methods can improve the efficiency and accuracy of CTL epitope studies. In this study, two HLA-A11-restricted epitopes derived from human papillomavirus (HPV)18 E6 oncoprotein were identified. HLA-A11-transgenic mice immunized with these epitopes could specifically induce interferon-gamma (IFNgamma) production, cytotoxicity and peptide/HLA-A11 tetramer binding in CD8(+) T-cells. To study intracellular processing of CTL epitopes, we constructed a DNA plasmid containing an endoplasmic reticulum (ER) targeting sequence as well as the HPV18 E6 and E7 genes (pEK/HPV18E6E7). CTL responses against peptide-pulsed T2/A11 cells could be detected after immunizing HLA-A11-transgenic mice with pEK/HPV18E6E7. Furthermore, the identified peptides could stimulate T-cells to secrete IFNgamma from HPV18-infected patients. Our results demonstrate that the antigenic E6 peptides derived from HPV18 are potential candidates for the treatment of HPV 18-associated tumors in HLA-A11(+) populations.