Analysis on electrical characteristics of high-voltage GaN-based light-emitting diodes

In order to investigate their electrical characteristics, high-voltage light-emitting-diodes （HV-LEDs） each contain- ing four cells in series are fabricated. The electrical parameters including varying voltage and parasitic effect are studied. It is shown that the ideality factors （IFs） of the HV-LEDs with different numbers of cells are 1.6, 3.4, 4.7, and 6.4. IF increases linearly with the number of cells increasing. Moreover, the performance of the HV-LED with failure cells is examined, The analysis indicates that the failure cell has a parallel resistance which induces the leakage of the failure cell. The series resistance of the failure cell is 76.8 Ω, while that of the normal cell is 21.3 Ω. The scanning electron microscope （SEM） image indicates that different metal layers do not contact well. It is hard to deposit the metal layers in the deep isolation trenches. The fabrication process of HV-LEDs needs to be optimized.

Studying solutions for the fatigue of the FAST cable-net structure caused by the process of changing shape

The Five-hundred-meter Aperture Spherical Radio Telescope （FAST） is supported by a cable-net structure, whose change in shape leads to a stress range of approximately 500 MPa. This stress range is more than twice the standard recom- mended value. The cable-net structure is thus the most critical and fragile part of the FAST reflector system. In this study, we first search for a more appropriate deforma- tion strategy that reduces the stress amplitude generated by the process of changing shape. Second, we roughly estimate the tracking trajectory of the telescope during its service life, and conduct an extensive numerical investigation to assess the require- ments for fatigue resistance. Finally, we develop a new type of steel cable system that satisfies the cable requirements for construction of FAST.

Electroless copper-phosphorus coatings with the addition of silicon carbide (SiC) particles

Cu-P-silicon carbide （SiC） composite coatings were deposited by means of electroless plating.The effects of pH values,temperature,and different concentrations of sodium hypophosphite （NaH2PO2·H2O）,nickel sulfate （NiSO4·6H2O）,sodium citrate （C6H5Na3O7·2H2O） and SiC on the deposition rate and coating compositions were evaluated,and the bath formulation for Cu-P-SiC composite coatings was optimised.The coating compositions were determined using energy-dispersive X-ray analysis （EDX）.The corresponding optimal operating parameters for depositing Cu-P-SiC are as follows：pH 9;temperature,90oC;NaH2PO2·H2O concentration,125 g/L;NiSO4·6H2O concentration,3.125 g/L;SiC concentration,5 g/L;and C6H5Na3O7·2H2O concentration,50 g/L.The surface morphology of the coatings analysed by scanning electron microscopy （SEM） shows that Cu particles are uniformly distributed.The hardness and wear resistance of Cu-P composite coatings are improved with the addition of SiC particles and increase with the increase of SiC content.

HBV X-gene:A new serum marker for anti-HBV therapy monitoring

Objective:To address HBV serum nucleic acid markers for stages without apparent replica- tion.Methods:DNA and RNA sequence segments from the X,C and pre C/C regions produced succes- sively during replication were used as targets for quantitative PCR and RT/PCR.Results:The assays con- firmed the preferential formation of intermediates blocked at early stages.They persisted as the only de- tectable type of serum HBV DNA even after one year of therapy.At reentry into viral replication due to e- mergence of drug resistant mutants,lamivudine resistance produced exclusively incomplete DNA minus strands,whereas the wild type virus immediately synthesized complete DNA minus strands.Conclusion: PCR assays used for monitoring complete suppression of HBV replication must target the X gene region.

RESISTANCE CHANGEMENT OF COMPRESSION SENSIBLE CEMENT SPECIMENT UNDER DIFFERENT STRESSES

The resistivity of cement specimens mixed with carbon fibres under different pressures is studied. The results reveal that when pressure becomes larger and larger, the resistivity of speciments changes. The process can be di-vided into three stages; reversible sensing period, balance pe-riod, and sharp increasing period. These three periods re-spectively show the closure and opening of raw flaw in speci-mens , germination of fresh cracks and cracks extending to failure. The conducting mechanism is also analyzed. Ac-cording to the above characteristic of carbon fibre-cement specimen, it can be used as an intrinsic smart material to be ap-plied in the non-destructive detection of concrete dams,ect.

Cold Resistant Properties of High Modulus Polyurethane

Six kinds of polyurethane （PU） elastomers were prepared based on different polyesters, polyethers and chain extenders. The structure, mechanical properties and cold resistant properties of PU were systematically investigated by FTIR, XRD, DMTA,universal testing machine and flex ductility machine. The results show that Tg of soft segment is the main factor of the cold resistant properties of polyurethane elastomer. Compared with the same relative molecular mass of the polyester and the polyether, the polyether flexibility is better, the glass transition temperature （Tg） is lower and the cold resistant properties is remarkable, for example the cold resistant properties of PU based on poly （tetramethylene glycol）, 1, 4-BG and MDI achieves the fifth level. The physics performances of polyurethane elastomers, such as breakdown strength, Young＇s modulus and the cold resistant properties, are all superior.

Evidence of active oviposition avoidance to systemically applied imidacloprid in the Colorado potato beetle

Agricultural pests can develop behavioral resistance to insecticides by choosing to feed or oviposit on insecticide-free hosts.As young larvae have relatively low mobility,oviposition preferences from female adults may play a critical role in shaping the evolu-tionary trajectory of pest populations.While oviposition avoidance of insecticide-treated hosts was found in different agriculture pests,it remains unclear whether female adults actively choose to occupy insecticide-free hosts.To address this question,we investigated feeding and oviposition preferences between imidacloprid-treated and imidacloprid-free plants in the Colorado potato beetle,Leptinotarsa decemlineata Say,a major potato pest.We performed behavioral choice assays on two strains that differed in both fecundity and insecticide resistance.We found that one strain preferred to feed on the insecticide-free plants and that this preference is not innate.Meanwhile,the other strain chose plants for feeding and oviposition randomly.Further analyses of the moving patterns of the beetles suggested that the oviposition preference in the first strain is likely due to active learning.

Tangnaikang improves insulin resistance and β-cell apoptosis by ameliorating metabolic inflammation in SHR.Cg-Lepr^(cp)/NDmcr rats

OBJECTIVE: To investigate the effects of Tangnaikang(TNK), a mixture of five herbal plant extracts,on inflammation-mediated insulin resistance andβ-cell apoptosis in SHR.Cg-Leprcp/NDmcr(SHR-cp)rats.METHODS: Seven-week-old SHR-cp rats were randomly divided into a control(CON) group and a TNK(3.24 g/kg) group. Wistar-Kyoto rats at the same age were used as the normal control group.After 7 weeks of continuous intragastric administration of TNK, the glucose metabolic status and insulin sensitivity of the rats were evaluated by assessing fasting serum glucose(FBG), the oral glucose tolerance test(OGTT), fasting serum insulin(FINS),and the insulin sensitivity index(ISI). Serum tumor necrosis factor-α(TNF-α), interleukin-6(IL-6), C-reactive protein(CRP) and adiponectin were measured via enzyme-linked immunosorbent assays.Macrophage infiltration and apoptosis in adipose tissues were detected through F4/80 immunohistochemistry and the terminal deoxynucleotidyl transferase d UTP nick end labeling(TUNEL) assay. Islet morphology and β-cell apoptosis were investigated using double immunofluorescence staining and the TUNEL assay. The expression of cytokine genes in adipose tissue, the liver, and the pancreas was detected in real-time polymerase chain reaction assays. The expression and phosphorylation levels of insulin signaling-, inflammation-, and β-cell survival-related proteins in the liver and pancreas of SHR-cp rats were detected by western blotting.RESULTS: TNK(3.24 g/kg) treatment significantly decreased body weight, FBG and FINS; improved impaired glucose tolerance; increased the ISI; reduced serum levels of TNF-α, CRP and IL-6; and increased serum adiponectin. The m RNA expression of inflammatory markers was markedly reduced in the liver, pancreas, and adipose tissue. F4/80-and TUNEL-positive cells in adipose tissues were decreased, as was the number of TUNEL-positiveβ-cells. The phosphorylation of c-Jun N-terminal kinase and that of insulin receptor substrate-1 at serines 307 and 1101 was significantly decreased.In the pancreas, the expression of nuclear factor kappa-light chain-enhancer of activated B cells-p65 was significantly decreased, and phosphoinositide3-kinase and IRS-2 were significantly increased.CONCLUSION: TNK was able to improve insulin resistance and β-cell apoptosis in SHR-cp rats, which might be associated with its ability to relieve the overall and local metabolic inflammatory responses observed in SHR-cp rats.

In Situ-Induced Multivalent Anticancer Drug Clusters in Cancer Cells for Enhancing Drug Efficacy

Increasing intracellular drug concentration is an effec-tive way for cancer chemotherapeutics to enhance efficacy and combat drug resistance.In this work,a series of anticancer drug conjugates were prepared by linking thiol-modified oligo(p-phenylene viny-lene)with paclitaxel,vincristine,teniposide,tamoxi-fen,doxorubicin,or podophyllotoxin(OPV-S-Drugs)through a Michael addition reaction.