An initial step in amyloid-β (Aβ) production includes amyloid precursor protein (APP) cleavage vi... more An initial step in amyloid-β (Aβ) production includes amyloid precursor protein (APP) cleavage via β-Site amyloid precursor protein cleaving enzyme 1 (BACE1). Increased levels of brain Aβ have been implicated in the pathogenesis of Alzheimer's disease (AD). Thus, β-secretase represents a primary target for inhibitor drug development in AD. In this study, aptamers were obtained from combinatorial oligonucleotide libraries using a technology referred to as systematic evolution of ligands by exponential enrichment (SELEX). A purified human BACE1 extracellular domain was used as a target to conduct an in vitro selection process using SELEX. Two DNA aptamers were capable of binding to BACE1 with high affinity and good specificity, with Kd values in the nanomolar range. We subsequently confirmed that one aptamer, A1, exhibited a distinct inhibitory effect on BACE1 activity in an AD cell model. We detected the effects of M17-APPsw cells that stably expressed Swedish mutant APP after ap...
2011 5th International Conference on Bioinformatics and Biomedical Engineering, 2011
Rabbit hemorrhagic disease virus (RHDV) and myxoma virus (MV) are the two main viruses that cause... more Rabbit hemorrhagic disease virus (RHDV) and myxoma virus (MV) are the two main viruses that cause serious virus diseases in rabbit population. MV, a pox virus, has been proved to be a good recombinant vaccine vector. In this study we have developed a recombinant virus using MV as a vector against both the myxomatosis and rabbit hemorrhagic disease (RHD). We used the nonessential gene MST3N of MV as the insertion site. The recombinant viruses expressed the RHDV major capsid protein (VP60) and the selectable marker GFP. The pure recombinant viruses were achieved after several rounds of plaque screening. Replication of MST3N-knockout recombinant virus MV-VP60 in Rabbit kidney cell (RK13) was unimpaired, compared with wild type virus MV.
The multiple-channel reactions OH + SiH (CH 3) 3 → products (R1) and the single-channel reaction ... more The multiple-channel reactions OH + SiH (CH 3) 3 → products (R1) and the single-channel reaction OH + Si(CH 3) 4 → Si(CH 3) 3 CH 2 + H 2 O (R2) have been studied by means of the direct dynamics method at the BMC-CCSD//MP2/6-311+G(2d,2p) level. The optimized geometries, frequencies and minimum energy path are all obtained at the MP2/6-311+G(2d,2p) levels, and energy information is further refined by the BMC-CCSD (single-point) level. The rate constants for every reaction channels are calculated by canonical variational transition states theory (CVT) with small-curvature tunneling (SCT) contributions over the temperature range 200-2,000 K. The theoretical total rate constants are in good agreement with the available experimental data, and the three-parameter expression k 1 = 2.53× 10 −21 T 3.14 exp(1, 352.86/T), k 2 = 6.00 × 10 −19 T 2.54 exp(−106.11/T) (in unit of cm 3 molecule −1 s −1) over the temperature range 200-2,000 K are given. Our calculations indicate that at the low temperature range, for reaction R1, Habstraction is favored for the SiH group, while the abstraction from the CH 3 group is a minor channel.
A novel pressurised chamber was designed to construct a special purpose test rig to achieve satur... more A novel pressurised chamber was designed to construct a special purpose test rig to achieve saturated liquid state of refrigerants for lubricated rolling contact fatigue experiments. Traditional bench testing using refrigerants as the lubricant is difficult due to the gaseous phase at standard atmospheric conditions. Pressurising the concentrated contact test chamber is therefore necessary to evaluate at a liquid state and therefore simulate practical applications. The gas/liquid phase transitions have a significant influence on the lubricant properties and hence wear mechanisms. It is necessary to modify the wear test conditions for the Hydrocarbon (HC) and Hydrofluorocarbon refrigerants to obtain realistic simulation of refrigerator compressor tests. The chamber design and test rig are described in this paper. A preliminary experimental study of the influence of the HC (R600a) on rolling wear of the silicon nitride (Si 3 N 4)/steel elements using the pressurised chamber is presented. Rolling fatigue test methods are adopted to measure the wear performance of silicon nitride/steel bearing materials. In this case the rolling wear mechanisms of Si 3 N 4 were measured using R600a refrigerant lubrication.
CdSe and CdSe@CdS semiconductor nanocrystals have been synthesized in aqueous solutions, using so... more CdSe and CdSe@CdS semiconductor nanocrystals have been synthesized in aqueous solutions, using sodium citrate as a stabilizer. Although initially these quantum dots display photoluminescence with very low quantum yields, upon prolonged illumination with visible light, enhancements up to 5000% have been measured. This leads to aqueous quantum dots with high luminescence, which can have important implications in biological and other applications. A distinct correlation between the photocorrosion process and the photoactivation process is observed. The primary reason for luminescence enhancement is considered to be the smoothing of the CdSe core surface. Importantly, even stronger activation was observed in silica-and CdS-coated nanocolloids where the CdSe core was expected to be shielded from photocorrosion. Preferential adsorption of oxygen molecules in the porous silicate shell accelerates the photocorrosion process. In CdS-coated particles, incomplete coating of the original particles is postulated, which is accompanied by the reforming of the CdS coat because of ionic diffusion at the interface on the newly opening areas with smoother surfaces.
A multi-sensor approach was used to determine high-resolution porewater gradients of Ca 2+ , CO 2... more A multi-sensor approach was used to determine high-resolution porewater gradients of Ca 2+ , CO 2À 3 ; H + and O 2 in sediment cores along a depth transect from eutrophic Lake Sempach (Switzerland). We quantified the reproducibility of measurements and analyzed concentration profiles with a one-dimensional diffusion-reaction model to quantify benthic fluxes. Calculation of oxic respiration in the sediment showed that almost all settled organic carbon was degraded with O 2 at shallow depths while only 28% was decomposed aerobically at the deepest location. Fluxes were highest at 8 m depth (24.4 mmol m À2 d À1) and lowest at the deepest site of 85 m (7.1 mmol m À2 d À1). Dissolution of calcite from the sediment was also depth dependent. A total of 1.1 mmol m À2 d À1 was found for the shallowest site, and values decreased with depth to 0.6 mmol m À2 d À1 at the deepest site.
An integrative non-conjugative extrachromosomal genetic element, denoted as pSSVi, has been isola... more An integrative non-conjugative extrachromosomal genetic element, denoted as pSSVi, has been isolated from a Sulfolobus solfataricus P2 strain and was characterized. This genetic element is a double-stranded DNA of 5740 bp in size and contains eight open reading frames (ORFs). It resembles members of the pRN plasmid family in genome organization but shows only weak similarity to the latter in conserved regions. pSSVi has a copG gene similar to that of a pRN plasmid, encodes a large replication protein which, unlike a typical pRN RepA, contains no polymerase/primase domain, and lacks the plrA gene. Interestingly, pSSVi encodes an SSV-type integrase which probably catalyzes the integration of its genome into a specific site (a tRNA Arg gene) in the S. solfataricus P2 genome. Like pSSVx, pSSVi can be packaged into a spindle-like viral particle and spread with the help of SSV1 or SSV2. In addition, both SSV1 and SSV2 appeared to replicate more efficiently in the presence of pSSVi. Given the versatile genetic abilities, pSSVi appears to be well suited for a role in horizontal gene transfer.
Optically transparent superhydrophobic silica-based films were obtained by means of sol-gel proce... more Optically transparent superhydrophobic silica-based films were obtained by means of sol-gel processing and self-assembly (SA). Desired surface roughness was obtained by tuning the microstructures of the sol-gels through careful control of hydrolysis and condensation reactions of various silica precursors during sol-gel processing, whereas modification of surface chemistry was done by introducing a monolayer through surface condensation reaction. Such coatings were obtained by dip-coating the silica sols directly onto substrates, followed with self-assembly. The resultant silica-based coatings showed optical transparency higher than 90%, and the reflection lower than 10%, and the best advancing and receding water contact angles were found to be of approximately 165j/115j. Such coatings can have applications where anti-reflection, optical transparency and superhydrophobicity are required, in addition to low temperature processing. In addition, such films can be made at room temperature involving no expensive equipment or tedious processing, and be readily coated on various substrates.
One-dimensional aggregates of CdTe nanoparticles were prepared by an exceptionally simple method ... more One-dimensional aggregates of CdTe nanoparticles were prepared by an exceptionally simple method of self-assembly initiated by partial removal of the stabilizing shell. The driving force of the particle selforganization is likely to be the dipole-dipole attraction between the nanoparticle cores. The obtained nanoparticle chains can be easily transferred on any substrate. Steady-state and time-resolved luminescent spectroscopes revealed strong Forster resonance energy transfer (FRET) between the particles, which led to the migration of excitation along the chain similarly to the waveguiding of light observed for chains of metal nanoparticles. The efficiency of FRET quenching in this one-dimensional system is comparable to that in three-dimensional packed nanoparticle solids despite a substantially smaller number of adjacent particles. The strong coupling of the donor and acceptor excited states is likely due to short inter-nanoparticle distances and partial ground-state dipole alignment taking place during the chain formation.
Poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV), synthesized via microorganisms, has been paid gr... more Poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV), synthesized via microorganisms, has been paid great attention. However, its biodegradation behavior in pilot-scale composting conditions has not been investigated. In this paper, the biodegradability of PHBV containing 3 mol% of hydroxyvalerate (HV) was tested under composting conditions on both a pilot and a laboratory scale. In the pilot-scale composting conditions, parameters such as pH value, temperature and the amounts of oxygen and CO 2 produced were determined periodically. In the laboratory-scale controlled composting, the evolved CO 2 was measured so as to calculate the degree of biodegradation of PHBV. It was found that the biodegradation behavior of PHBV in the pilot-scale composting conditions was similar with that in the laboratory-scale. The PHBV film was completely disintegrated in the pilot-scale composting test, and the degree of biodegradation was 81% in the laboratory-scale control composting test. The variations of molecular weight and morphology of PHBV films during composting were also monitored.
Voltage-gated cation channels regulate neuronal excitability through selective ion flux. NALCN, a... more Voltage-gated cation channels regulate neuronal excitability through selective ion flux. NALCN, a member of a protein family that is structurally related to the a1 subunits of voltage-gated sodium/calcium channels, was recently shown to regulate the resting membrane potentials by mediating sodium leak and the firing of mouse neurons. We identified a role for the Caenorhabditis elegans NALCN homologues NCA-1 and NCA-2 in the propagation of neuronal activity from cell bodies to synapses. Loss of NCA activities leads to reduced synaptic transmission at neuromuscular junctions and frequent halting in locomotion. In vivo calcium imaging experiments further indicate that while calcium influx in the cell bodies of egg-laying motorneurons is unaffected by altered NCA activity, synaptic calcium transients are significantly reduced in nca loss-of-function mutants and increased in nca gain-of-function mutants. NCA-1 localizes along axons and is enriched at nonsynaptic regions. Its localization and function depend on UNC-79, and UNC-80, a novel conserved protein that is also enriched at nonsynaptic regions. We propose that NCA-1 and UNC-80 regulate neuronal activity at least in part by transmitting depolarization signals to synapses in C. elegans neurons.
BACKGROUND The narrow host range of Mycobacterium leprae and the fact that it is refractory to gr... more BACKGROUND The narrow host range of Mycobacterium leprae and the fact that it is refractory to growth in culture has limited research on and the biologic understanding of leprosy. Host genetic factors are thought to influence susceptibility to infection as well as disease progression. METHODS We performed a two-stage genomewide association study by genotyping 706 patients and 1225 controls using the Human610-Quad BeadChip (Illumina). We then tested three independent replication sets for an association between the presence of leprosy and 93 single-nucleotide polymorphisms (SNPs) that were most strongly associated with the disease in the genomewide association study. Together, these replication sets comprised 3254 patients and 5955 controls. We also carried out tests of heterogeneity of the associations (or lack thereof) between these 93 SNPs and disease, stratified according to clinical subtype (multibacillary vs. paucibacillary). RESULTS We observed a significant association (P<1.00×10 −10) between SNPs in the genes CCDC122, C13orf31, NOD2, TNFSF15, HLA-DR, and RIPK2 and a trend toward an association (P = 5.10×10 −5) with a SNP in LRRK2. The associations between the SNPs in C13orf31, LRRK2, NOD2, and RIPK2 and multibacillary leprosy were stronger than the associations between these SNPs and paucibacillary leprosy. CONCLUSIONS Variants of genes in the NOD2-mediated signaling pathway (which regulates the innate immune response) are associated with susceptibility to infection with M. leprae.
We performed a genome-wide association study (GWAS) of systemic lupus erythematosus (SLE) in a Ch... more We performed a genome-wide association study (GWAS) of systemic lupus erythematosus (SLE) in a Chinese Han population by genotyping 1,047 cases and 1,205 controls using Illumina Human610-Quad BeadChips and replicating 78 SNPs in two additional cohorts (3,152 cases and 7,050 controls). We identified nine new susceptibility loci (ETS1, IKZF1, RASGRP3, SLC15A4, TNIP1, 7q11.23, 10q11.22, 11q23.3 and 16p11.2; 1.77 × 10 −25 ≤ P combined ≤ 2.77 × 10 −8) and confirmed seven previously reported loci (BLK, IRF5, STAT4, TNFAIP3, TNFSF4, 6q21 and 22q11.21; 5.17 × 10 −42 ≤ P combined ≤ 5.18 × 10 −12). Comparison with previous GWAS findings highlighted the genetic heterogeneity of SLE susceptibility between Chinese Han and European populations. This study not only advances our understanding of the genetic basis of SLE but also highlights the value of performing GWAS in diverse ancestral populations. Systemic lupus erythematosus (SLE) is a prototypic systemic autoimmune disease that is characterized by a diverse array of autoantibody production, complement activation, immune complex deposition and tissue and organ damage 1 and that is influenced by both genetic and environmental factors 2. SLE affects predominantly women (prevalence ratio of women to men is 9:1), particularly during the childbearing years. There are marked disparities in SLE incidence and prevalence worldwide; SLE prevalence varies among different ethnic and geographical populations 3. The prevalence of SLE ranges from 31 to 70 cases per 100,000 persons among Chinese populations 4 and from 7 to 71 cases per 100,000 persons in European populations 5 , and lupus nephritis is more prevalent in Chinese populations than in European populations 3. The ethnic and genetic heterogeneity of SLE may contribute to the complexity of its clinical manifestation. Over the past two decades, numerous studies have identified multiple genetic factors related to SLE. In particular, four recent genome-wide association studies (GWAS) of SLE in European populations have identified more than 20 robust susceptibility genes and/or loci 6-9. The genetic heterogeneity between ethnic populations has
A second generation human haplotype map of over 3.1 million SNPs The International HapMap Consort... more A second generation human haplotype map of over 3.1 million SNPs The International HapMap Consortium* We describe the Phase II HapMap, which characterizes over 3.1 million human single nucleotide polymorphisms (SNPs) genotyped in 270 individuals from four geographically diverse populations and includes 25-35% of common SNP variation in the populations surveyed. The map is estimated to capture untyped common variation with an average maximum r 2 of between 0.9 and 0.96 depending on population. We demonstrate that the current generation of commercial genome-wide genotyping products captures common Phase II SNPs with an average maximum r 2 of up to 0.8 in African and up to 0.95 in non-African populations, and that potential gains in power in association studies can be obtained through imputation. These data also reveal novel aspects of the structure of linkage disequilibrium. We show that 10-30% of pairs of individuals within a population share at least one region of extended genetic identity arising from recent ancestry and that up to 1% of all common variants are untaggable, primarily because they lie within recombination hotspots. We show that recombination rates vary systematically around genes and between genes of different function. Finally, we demonstrate increased differentiation at non-synonymous, compared to synonymous, SNPs, resulting from systematic differences in the strength or efficacy of natural selection between populations.
CdTe nanowires with bristled SiO 2 coatings resembling nanoscale centipedes were produced in a mo... more CdTe nanowires with bristled SiO 2 coatings resembling nanoscale centipedes were produced in a modified Sto 1ber process when mercaptosuccinic acid was used as a stabilizer. The reason for the unusual morphology of the coating is believed to be the nonuniform distribution of the stabilizers on the surface of the nanowire. Atomistic calculations of CdTe nanoparticles as a simplified model of a nanowire surface reveal that phase separation of the mercaptosuccinic acid and (3-mercaptopropyl)trimethoxysilane is an energetically favorable process. These data indicate that the heterogeneity of the nanocolloid surface is an important property that may be taken advantage of for preparation of nanostructures of high complexity. From a practical perspective, the centipede nanowires can be a uniquely useful material for high-strength nanoscale composites.
Advances in semiconductor nanocolloids have provided a new set of materials with unique optical a... more Advances in semiconductor nanocolloids have provided a new set of materials with unique optical and electrical properties, which recently have grabbed biologists and biomedical engineers' attention for applications such as biolabels, biosensors, and image-contrast agents. These nanosemiconductors have also been used to fabricate devices for applications such as drug delivery and medical therapeutics. In this review, we introduce some of the latest examples of semiconducting nanostructures that have been applied successfully to problems in biotechnology, with a special focus on biosensing and bioimaging. We first describe how to take advantage of the optical properties of semiconductor quantum dots in these two research fields. In addition, we give a brief introduction to biosensors based on field-effect transistors (FETs) made of one-dimensional semiconductor nanowires and carbon nanotubes. Finally, we discuss the future development of semiconductor nanomaterials in the biological field.
Experimental results of rolling contact fatigue on ceramic bearing elements with refrigerant lubr... more Experimental results of rolling contact fatigue on ceramic bearing elements with refrigerant lubrication are presented. Residual stress measurements located on the contact path and other locations on the surface are described. An X-ray method was employed. Residual stress measurements are helpful in predicting rolling contact fatigue life. In addition, analysing the relationship of residual stress with rolling contact fatigue is an important study, which will provide guidelines on the design, process and manufacturing of these elements. During this research, ring crack defects were induced in ceramic rolling contact bearing elements. A compressive residual stress value of −73 MPa near the ring crack and a comparatively lower value of −12 MPa on the contact indicate sub-surface crack initiation and propagation. The average fatigue spall ranges from 100 to 148 m in depth. Within the spall area residual stress measurements suggest that compressive residual stress is relieved much faster in the region of sub-surface damage.
Bismuth tungstate (Bi2WO6) nanocrystals with the average size of ca. 12 nm had been successfully ... more Bismuth tungstate (Bi2WO6) nanocrystals with the average size of ca. 12 nm had been successfully synthesized by a simple solvothermal method at 180 °C for 2 h. The as-synthesized Bi2WO6 nanocrystals were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV–vis diffuse reflectance spectra, and N2 adsorption–desorption measurements. The visible-light-driven photocatalytic activity of the sample was evaluated by photo-degradation of rhodamine-B
Mesostructured lamellar zirconia was synthesized in the hydrothermal systems using Cetyltrimethyl... more Mesostructured lamellar zirconia was synthesized in the hydrothermal systems using Cetyltrimethyl Ammonium Bromide (CTAB) as a template and zirconyl chloride as zirconium precursor. The as-prepared composites were characterized by X-ray diffraction (XRD), TG-DTA, and DR-UV techniques. The influences of hydrothermal aging time, total concentration of solution, different mole ratio of zirconyl chloride/surfactant, and post treatment on the structure of mesostructured
An initial step in amyloid-β (Aβ) production includes amyloid precursor protein (APP) cleavage vi... more An initial step in amyloid-β (Aβ) production includes amyloid precursor protein (APP) cleavage via β-Site amyloid precursor protein cleaving enzyme 1 (BACE1). Increased levels of brain Aβ have been implicated in the pathogenesis of Alzheimer's disease (AD). Thus, β-secretase represents a primary target for inhibitor drug development in AD. In this study, aptamers were obtained from combinatorial oligonucleotide libraries using a technology referred to as systematic evolution of ligands by exponential enrichment (SELEX). A purified human BACE1 extracellular domain was used as a target to conduct an in vitro selection process using SELEX. Two DNA aptamers were capable of binding to BACE1 with high affinity and good specificity, with Kd values in the nanomolar range. We subsequently confirmed that one aptamer, A1, exhibited a distinct inhibitory effect on BACE1 activity in an AD cell model. We detected the effects of M17-APPsw cells that stably expressed Swedish mutant APP after ap...
2011 5th International Conference on Bioinformatics and Biomedical Engineering, 2011
Rabbit hemorrhagic disease virus (RHDV) and myxoma virus (MV) are the two main viruses that cause... more Rabbit hemorrhagic disease virus (RHDV) and myxoma virus (MV) are the two main viruses that cause serious virus diseases in rabbit population. MV, a pox virus, has been proved to be a good recombinant vaccine vector. In this study we have developed a recombinant virus using MV as a vector against both the myxomatosis and rabbit hemorrhagic disease (RHD). We used the nonessential gene MST3N of MV as the insertion site. The recombinant viruses expressed the RHDV major capsid protein (VP60) and the selectable marker GFP. The pure recombinant viruses were achieved after several rounds of plaque screening. Replication of MST3N-knockout recombinant virus MV-VP60 in Rabbit kidney cell (RK13) was unimpaired, compared with wild type virus MV.
The multiple-channel reactions OH + SiH (CH 3) 3 → products (R1) and the single-channel reaction ... more The multiple-channel reactions OH + SiH (CH 3) 3 → products (R1) and the single-channel reaction OH + Si(CH 3) 4 → Si(CH 3) 3 CH 2 + H 2 O (R2) have been studied by means of the direct dynamics method at the BMC-CCSD//MP2/6-311+G(2d,2p) level. The optimized geometries, frequencies and minimum energy path are all obtained at the MP2/6-311+G(2d,2p) levels, and energy information is further refined by the BMC-CCSD (single-point) level. The rate constants for every reaction channels are calculated by canonical variational transition states theory (CVT) with small-curvature tunneling (SCT) contributions over the temperature range 200-2,000 K. The theoretical total rate constants are in good agreement with the available experimental data, and the three-parameter expression k 1 = 2.53× 10 −21 T 3.14 exp(1, 352.86/T), k 2 = 6.00 × 10 −19 T 2.54 exp(−106.11/T) (in unit of cm 3 molecule −1 s −1) over the temperature range 200-2,000 K are given. Our calculations indicate that at the low temperature range, for reaction R1, Habstraction is favored for the SiH group, while the abstraction from the CH 3 group is a minor channel.
A novel pressurised chamber was designed to construct a special purpose test rig to achieve satur... more A novel pressurised chamber was designed to construct a special purpose test rig to achieve saturated liquid state of refrigerants for lubricated rolling contact fatigue experiments. Traditional bench testing using refrigerants as the lubricant is difficult due to the gaseous phase at standard atmospheric conditions. Pressurising the concentrated contact test chamber is therefore necessary to evaluate at a liquid state and therefore simulate practical applications. The gas/liquid phase transitions have a significant influence on the lubricant properties and hence wear mechanisms. It is necessary to modify the wear test conditions for the Hydrocarbon (HC) and Hydrofluorocarbon refrigerants to obtain realistic simulation of refrigerator compressor tests. The chamber design and test rig are described in this paper. A preliminary experimental study of the influence of the HC (R600a) on rolling wear of the silicon nitride (Si 3 N 4)/steel elements using the pressurised chamber is presented. Rolling fatigue test methods are adopted to measure the wear performance of silicon nitride/steel bearing materials. In this case the rolling wear mechanisms of Si 3 N 4 were measured using R600a refrigerant lubrication.
CdSe and CdSe@CdS semiconductor nanocrystals have been synthesized in aqueous solutions, using so... more CdSe and CdSe@CdS semiconductor nanocrystals have been synthesized in aqueous solutions, using sodium citrate as a stabilizer. Although initially these quantum dots display photoluminescence with very low quantum yields, upon prolonged illumination with visible light, enhancements up to 5000% have been measured. This leads to aqueous quantum dots with high luminescence, which can have important implications in biological and other applications. A distinct correlation between the photocorrosion process and the photoactivation process is observed. The primary reason for luminescence enhancement is considered to be the smoothing of the CdSe core surface. Importantly, even stronger activation was observed in silica-and CdS-coated nanocolloids where the CdSe core was expected to be shielded from photocorrosion. Preferential adsorption of oxygen molecules in the porous silicate shell accelerates the photocorrosion process. In CdS-coated particles, incomplete coating of the original particles is postulated, which is accompanied by the reforming of the CdS coat because of ionic diffusion at the interface on the newly opening areas with smoother surfaces.
A multi-sensor approach was used to determine high-resolution porewater gradients of Ca 2+ , CO 2... more A multi-sensor approach was used to determine high-resolution porewater gradients of Ca 2+ , CO 2À 3 ; H + and O 2 in sediment cores along a depth transect from eutrophic Lake Sempach (Switzerland). We quantified the reproducibility of measurements and analyzed concentration profiles with a one-dimensional diffusion-reaction model to quantify benthic fluxes. Calculation of oxic respiration in the sediment showed that almost all settled organic carbon was degraded with O 2 at shallow depths while only 28% was decomposed aerobically at the deepest location. Fluxes were highest at 8 m depth (24.4 mmol m À2 d À1) and lowest at the deepest site of 85 m (7.1 mmol m À2 d À1). Dissolution of calcite from the sediment was also depth dependent. A total of 1.1 mmol m À2 d À1 was found for the shallowest site, and values decreased with depth to 0.6 mmol m À2 d À1 at the deepest site.
An integrative non-conjugative extrachromosomal genetic element, denoted as pSSVi, has been isola... more An integrative non-conjugative extrachromosomal genetic element, denoted as pSSVi, has been isolated from a Sulfolobus solfataricus P2 strain and was characterized. This genetic element is a double-stranded DNA of 5740 bp in size and contains eight open reading frames (ORFs). It resembles members of the pRN plasmid family in genome organization but shows only weak similarity to the latter in conserved regions. pSSVi has a copG gene similar to that of a pRN plasmid, encodes a large replication protein which, unlike a typical pRN RepA, contains no polymerase/primase domain, and lacks the plrA gene. Interestingly, pSSVi encodes an SSV-type integrase which probably catalyzes the integration of its genome into a specific site (a tRNA Arg gene) in the S. solfataricus P2 genome. Like pSSVx, pSSVi can be packaged into a spindle-like viral particle and spread with the help of SSV1 or SSV2. In addition, both SSV1 and SSV2 appeared to replicate more efficiently in the presence of pSSVi. Given the versatile genetic abilities, pSSVi appears to be well suited for a role in horizontal gene transfer.
Optically transparent superhydrophobic silica-based films were obtained by means of sol-gel proce... more Optically transparent superhydrophobic silica-based films were obtained by means of sol-gel processing and self-assembly (SA). Desired surface roughness was obtained by tuning the microstructures of the sol-gels through careful control of hydrolysis and condensation reactions of various silica precursors during sol-gel processing, whereas modification of surface chemistry was done by introducing a monolayer through surface condensation reaction. Such coatings were obtained by dip-coating the silica sols directly onto substrates, followed with self-assembly. The resultant silica-based coatings showed optical transparency higher than 90%, and the reflection lower than 10%, and the best advancing and receding water contact angles were found to be of approximately 165j/115j. Such coatings can have applications where anti-reflection, optical transparency and superhydrophobicity are required, in addition to low temperature processing. In addition, such films can be made at room temperature involving no expensive equipment or tedious processing, and be readily coated on various substrates.
One-dimensional aggregates of CdTe nanoparticles were prepared by an exceptionally simple method ... more One-dimensional aggregates of CdTe nanoparticles were prepared by an exceptionally simple method of self-assembly initiated by partial removal of the stabilizing shell. The driving force of the particle selforganization is likely to be the dipole-dipole attraction between the nanoparticle cores. The obtained nanoparticle chains can be easily transferred on any substrate. Steady-state and time-resolved luminescent spectroscopes revealed strong Forster resonance energy transfer (FRET) between the particles, which led to the migration of excitation along the chain similarly to the waveguiding of light observed for chains of metal nanoparticles. The efficiency of FRET quenching in this one-dimensional system is comparable to that in three-dimensional packed nanoparticle solids despite a substantially smaller number of adjacent particles. The strong coupling of the donor and acceptor excited states is likely due to short inter-nanoparticle distances and partial ground-state dipole alignment taking place during the chain formation.
Poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV), synthesized via microorganisms, has been paid gr... more Poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV), synthesized via microorganisms, has been paid great attention. However, its biodegradation behavior in pilot-scale composting conditions has not been investigated. In this paper, the biodegradability of PHBV containing 3 mol% of hydroxyvalerate (HV) was tested under composting conditions on both a pilot and a laboratory scale. In the pilot-scale composting conditions, parameters such as pH value, temperature and the amounts of oxygen and CO 2 produced were determined periodically. In the laboratory-scale controlled composting, the evolved CO 2 was measured so as to calculate the degree of biodegradation of PHBV. It was found that the biodegradation behavior of PHBV in the pilot-scale composting conditions was similar with that in the laboratory-scale. The PHBV film was completely disintegrated in the pilot-scale composting test, and the degree of biodegradation was 81% in the laboratory-scale control composting test. The variations of molecular weight and morphology of PHBV films during composting were also monitored.
Voltage-gated cation channels regulate neuronal excitability through selective ion flux. NALCN, a... more Voltage-gated cation channels regulate neuronal excitability through selective ion flux. NALCN, a member of a protein family that is structurally related to the a1 subunits of voltage-gated sodium/calcium channels, was recently shown to regulate the resting membrane potentials by mediating sodium leak and the firing of mouse neurons. We identified a role for the Caenorhabditis elegans NALCN homologues NCA-1 and NCA-2 in the propagation of neuronal activity from cell bodies to synapses. Loss of NCA activities leads to reduced synaptic transmission at neuromuscular junctions and frequent halting in locomotion. In vivo calcium imaging experiments further indicate that while calcium influx in the cell bodies of egg-laying motorneurons is unaffected by altered NCA activity, synaptic calcium transients are significantly reduced in nca loss-of-function mutants and increased in nca gain-of-function mutants. NCA-1 localizes along axons and is enriched at nonsynaptic regions. Its localization and function depend on UNC-79, and UNC-80, a novel conserved protein that is also enriched at nonsynaptic regions. We propose that NCA-1 and UNC-80 regulate neuronal activity at least in part by transmitting depolarization signals to synapses in C. elegans neurons.
BACKGROUND The narrow host range of Mycobacterium leprae and the fact that it is refractory to gr... more BACKGROUND The narrow host range of Mycobacterium leprae and the fact that it is refractory to growth in culture has limited research on and the biologic understanding of leprosy. Host genetic factors are thought to influence susceptibility to infection as well as disease progression. METHODS We performed a two-stage genomewide association study by genotyping 706 patients and 1225 controls using the Human610-Quad BeadChip (Illumina). We then tested three independent replication sets for an association between the presence of leprosy and 93 single-nucleotide polymorphisms (SNPs) that were most strongly associated with the disease in the genomewide association study. Together, these replication sets comprised 3254 patients and 5955 controls. We also carried out tests of heterogeneity of the associations (or lack thereof) between these 93 SNPs and disease, stratified according to clinical subtype (multibacillary vs. paucibacillary). RESULTS We observed a significant association (P<1.00×10 −10) between SNPs in the genes CCDC122, C13orf31, NOD2, TNFSF15, HLA-DR, and RIPK2 and a trend toward an association (P = 5.10×10 −5) with a SNP in LRRK2. The associations between the SNPs in C13orf31, LRRK2, NOD2, and RIPK2 and multibacillary leprosy were stronger than the associations between these SNPs and paucibacillary leprosy. CONCLUSIONS Variants of genes in the NOD2-mediated signaling pathway (which regulates the innate immune response) are associated with susceptibility to infection with M. leprae.
We performed a genome-wide association study (GWAS) of systemic lupus erythematosus (SLE) in a Ch... more We performed a genome-wide association study (GWAS) of systemic lupus erythematosus (SLE) in a Chinese Han population by genotyping 1,047 cases and 1,205 controls using Illumina Human610-Quad BeadChips and replicating 78 SNPs in two additional cohorts (3,152 cases and 7,050 controls). We identified nine new susceptibility loci (ETS1, IKZF1, RASGRP3, SLC15A4, TNIP1, 7q11.23, 10q11.22, 11q23.3 and 16p11.2; 1.77 × 10 −25 ≤ P combined ≤ 2.77 × 10 −8) and confirmed seven previously reported loci (BLK, IRF5, STAT4, TNFAIP3, TNFSF4, 6q21 and 22q11.21; 5.17 × 10 −42 ≤ P combined ≤ 5.18 × 10 −12). Comparison with previous GWAS findings highlighted the genetic heterogeneity of SLE susceptibility between Chinese Han and European populations. This study not only advances our understanding of the genetic basis of SLE but also highlights the value of performing GWAS in diverse ancestral populations. Systemic lupus erythematosus (SLE) is a prototypic systemic autoimmune disease that is characterized by a diverse array of autoantibody production, complement activation, immune complex deposition and tissue and organ damage 1 and that is influenced by both genetic and environmental factors 2. SLE affects predominantly women (prevalence ratio of women to men is 9:1), particularly during the childbearing years. There are marked disparities in SLE incidence and prevalence worldwide; SLE prevalence varies among different ethnic and geographical populations 3. The prevalence of SLE ranges from 31 to 70 cases per 100,000 persons among Chinese populations 4 and from 7 to 71 cases per 100,000 persons in European populations 5 , and lupus nephritis is more prevalent in Chinese populations than in European populations 3. The ethnic and genetic heterogeneity of SLE may contribute to the complexity of its clinical manifestation. Over the past two decades, numerous studies have identified multiple genetic factors related to SLE. In particular, four recent genome-wide association studies (GWAS) of SLE in European populations have identified more than 20 robust susceptibility genes and/or loci 6-9. The genetic heterogeneity between ethnic populations has
A second generation human haplotype map of over 3.1 million SNPs The International HapMap Consort... more A second generation human haplotype map of over 3.1 million SNPs The International HapMap Consortium* We describe the Phase II HapMap, which characterizes over 3.1 million human single nucleotide polymorphisms (SNPs) genotyped in 270 individuals from four geographically diverse populations and includes 25-35% of common SNP variation in the populations surveyed. The map is estimated to capture untyped common variation with an average maximum r 2 of between 0.9 and 0.96 depending on population. We demonstrate that the current generation of commercial genome-wide genotyping products captures common Phase II SNPs with an average maximum r 2 of up to 0.8 in African and up to 0.95 in non-African populations, and that potential gains in power in association studies can be obtained through imputation. These data also reveal novel aspects of the structure of linkage disequilibrium. We show that 10-30% of pairs of individuals within a population share at least one region of extended genetic identity arising from recent ancestry and that up to 1% of all common variants are untaggable, primarily because they lie within recombination hotspots. We show that recombination rates vary systematically around genes and between genes of different function. Finally, we demonstrate increased differentiation at non-synonymous, compared to synonymous, SNPs, resulting from systematic differences in the strength or efficacy of natural selection between populations.
CdTe nanowires with bristled SiO 2 coatings resembling nanoscale centipedes were produced in a mo... more CdTe nanowires with bristled SiO 2 coatings resembling nanoscale centipedes were produced in a modified Sto 1ber process when mercaptosuccinic acid was used as a stabilizer. The reason for the unusual morphology of the coating is believed to be the nonuniform distribution of the stabilizers on the surface of the nanowire. Atomistic calculations of CdTe nanoparticles as a simplified model of a nanowire surface reveal that phase separation of the mercaptosuccinic acid and (3-mercaptopropyl)trimethoxysilane is an energetically favorable process. These data indicate that the heterogeneity of the nanocolloid surface is an important property that may be taken advantage of for preparation of nanostructures of high complexity. From a practical perspective, the centipede nanowires can be a uniquely useful material for high-strength nanoscale composites.
Advances in semiconductor nanocolloids have provided a new set of materials with unique optical a... more Advances in semiconductor nanocolloids have provided a new set of materials with unique optical and electrical properties, which recently have grabbed biologists and biomedical engineers' attention for applications such as biolabels, biosensors, and image-contrast agents. These nanosemiconductors have also been used to fabricate devices for applications such as drug delivery and medical therapeutics. In this review, we introduce some of the latest examples of semiconducting nanostructures that have been applied successfully to problems in biotechnology, with a special focus on biosensing and bioimaging. We first describe how to take advantage of the optical properties of semiconductor quantum dots in these two research fields. In addition, we give a brief introduction to biosensors based on field-effect transistors (FETs) made of one-dimensional semiconductor nanowires and carbon nanotubes. Finally, we discuss the future development of semiconductor nanomaterials in the biological field.
Experimental results of rolling contact fatigue on ceramic bearing elements with refrigerant lubr... more Experimental results of rolling contact fatigue on ceramic bearing elements with refrigerant lubrication are presented. Residual stress measurements located on the contact path and other locations on the surface are described. An X-ray method was employed. Residual stress measurements are helpful in predicting rolling contact fatigue life. In addition, analysing the relationship of residual stress with rolling contact fatigue is an important study, which will provide guidelines on the design, process and manufacturing of these elements. During this research, ring crack defects were induced in ceramic rolling contact bearing elements. A compressive residual stress value of −73 MPa near the ring crack and a comparatively lower value of −12 MPa on the contact indicate sub-surface crack initiation and propagation. The average fatigue spall ranges from 100 to 148 m in depth. Within the spall area residual stress measurements suggest that compressive residual stress is relieved much faster in the region of sub-surface damage.
Bismuth tungstate (Bi2WO6) nanocrystals with the average size of ca. 12 nm had been successfully ... more Bismuth tungstate (Bi2WO6) nanocrystals with the average size of ca. 12 nm had been successfully synthesized by a simple solvothermal method at 180 °C for 2 h. The as-synthesized Bi2WO6 nanocrystals were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV–vis diffuse reflectance spectra, and N2 adsorption–desorption measurements. The visible-light-driven photocatalytic activity of the sample was evaluated by photo-degradation of rhodamine-B
Mesostructured lamellar zirconia was synthesized in the hydrothermal systems using Cetyltrimethyl... more Mesostructured lamellar zirconia was synthesized in the hydrothermal systems using Cetyltrimethyl Ammonium Bromide (CTAB) as a template and zirconyl chloride as zirconium precursor. The as-prepared composites were characterized by X-ray diffraction (XRD), TG-DTA, and DR-UV techniques. The influences of hydrothermal aging time, total concentration of solution, different mole ratio of zirconyl chloride/surfactant, and post treatment on the structure of mesostructured
Uploads
Papers by Ying Wang