133 research outputs found
Magnetism driven dislocation dissociation, cross-slip and mobility in NiAl
We have examined the interplay between magnetism and dislocation core properties in NiAl alloys using quantum mechanics/molecular mechanics simulations. We observe the magnetism-driven site preference of Fe and Co impurities at the dislocation core. When occupying the Ni sublattice, Fe and Co impurities are found to induce spontaneous dislocation cross slip. When occupying the Al sublattice, the impurities render the originally undissociated dislocation to split into two partials. Finally we observe the magnetism-driven dislocation mobility when Fe impurity occupies the Al sublattice, which has also been discovered experimentally. The magnetic interaction between the impurities and the host atoms is responsible for the significant changes in the dislocation core structure and mobilityPhysical Review B 82(6), 060404R. (2010)2469-995
Error analysis and applications of a general QM/MM approach
Combing computational efficiency and accuracy, quantum mechanic/molecular mechanic (QM/MM) methods are promising for understanding and predicting materials properties at atomic scales. We present a general QM/MM method that can be implemented in a variety of QM and MM combinations; we focus on a tight-binding and a plane-wave pseudopotential methods for the QM part and the Stillinger-Weber and EAM potentials for the MM part. The QM/MM coupling errors are analyzed. It is found that a sufficient size of the coupling region and the buffer zone is crucial in minimizing the coupling errors. On the other hand, the size of the weighting zone turns out to be less important. The QM/MM method is applied to model the dynamical propagation of Si cracks with different orientations and under different mode I loadings. The QM/MM method is found to correctly reproduce the brittle fracture of Si, whereas the SW potential fails to do the same. The QM/MM method is also used to study the ductile fracture in Au and compared to the EAM potential. Finally, the QM/MM method is applied study the vacancy diffusion in a Cu grain boundary. The QM/MM results compare very well to the previous EAM results.Computational Materials Science 50(2), 714-719. (2010)0927-025
Construction and Evaluation of the Brucella Double Gene Knock-out Vaccine Strain MB6 Δbp26ΔwboA (RM6)
Brucellosis is a serious zoonotic infection worldwide. To date, vaccination is the most effective measure against brucellosis. This study was aimed at obtaining a vaccine strain that has high protective efficacy and low toxicity, and allows vaccination to be differentiated from infection. Using homologous recombination, we constructed a double gene-deletion Brucella strain MB6 Δbp26ΔwboA (RM6) and evaluated its characteristics, safety and efficacy. The RM6 strain had good proliferative ability and stable biological characteristics in vivo and in vitro. Moreover, it had a favorable safety profile and elicited specific immune responses in mice and sheep. The RM6 strain may have substantial practical application value
Development and Efficacy Evaluation of an SP01-adjuvanted Inactivated Escherichia Coli Mutant Vaccine Against Bovine Coliform Mastitis
Escherichia coli ( E. coli ) is one of the most common pathogens causing clinical mastitis in cattle, but no vaccine is available to prevent this disease in China. Therefore, development of an E. coli vaccine against bovine clinical mastitis is urgently needed. The candidate vaccine (Ch-O111-1) and challenge (LZ06) strains were screened from milk samples of cows with clinical mastitis. To extend the cross-protection of the Ch-O111-1 strain, we deleted the galE gene fragment of the Ch-O111-1 strain through homologous recombination between the Ch-O111-1 strain and pCVD442/ΔgalE plasmid, which was identified through conventional methods, including PCR, SDS-PAGE and sequencing. The Ch-O111-1/ΔgalE (Z9) strain was characterized by extensive cross-reactivity and attenuated virulence. We prepared inactivated Z9 vaccines with different adjuvants. Immunization of inactivated Z9 antigen induced adjuvant-, dosage- and inoculation time-dependent antibody titers in cows and mice. Furthermore, immunization with SP01-adjuvanted inactivated Z9 vaccine protected cows against severe clinical mastitis caused by LZ06 and protected mice against death due to LZ06. An SP01-adjuvanted inactivated Z9 vaccine was successfully developed and found to protect cows against severe mastitis caused by Escherichia coli
A hydrogel based localized release of colistin for antimicrobial treatment of burn wound infection
There is an urgent unmet medical need for new treatments for wound and burn infections caused by multidrug-resistant (MDR) Gram-negative ‘superbugs’, especially the problematic Pseudomonas aeruginosa. In this work we report the incorporation of colistin, a potent lipopeptide into a self-healable hydrogel (via dynamic imine bond formation) following the chemical reaction between the amine groups present in glycol chitosan and an aldehyde modified poly (ethylene glycol) (PEG). The storage module (G’) of the colistin-loaded hydrogel ranged from 1.3 kPa to 5.3 kPa by varying the amount of the cross-linker and colistin loading providing different options for topical wound healing. The majority of the colistin is released from the hydrogel within 24 h and remains active as demonstrated by both antibacterial in vitro disk diffusion and time-kill assays. Moreover and pleasingly, the colistin-loaded hydrogel performed almost equally well as native colistin against both the colistin-sensitive and also colistin-resistant P. aeruginosa strain in the in vivo animal 'burn' infection model despite exhibiting a slower killing profile in vitro. Based on this antibiotic performance along with the biodegradability of the product, we believe the colistin-loaded hydrogel to be a potential localized wound-healing formulation to treat burn wounds against microbial infection
Identification of the U-box gene family in peach (Prunus persica) and functional analysis of PpPUB20 in response to salt stress
BackgroundWith the rising proportion of saline soils in the global irrigated soil area, improving salt stress tolerance in peach is of great significance and value for the development of peach industry. Plant U-box proteins (PUBs) are widely involved in various stress response processes. In this study, genome-wide identification and analysis of PUBs genes in cultivated peach were carried out, and the expression profiles of peach PUB genes in different tissues of peach as well as their responses under salt stress were also investigated.MethodsThe genome-wide identification of PUBs genes in cultivated peach was analysed by gene localisation, gene structure and evolutionary analysis. Subsequently, the expression profiles of PpPUB genes in different tissues of peach and the changes in the relative expression of peach PUB genes under ABA, GA3, IAA, 6-BA treatments, low-temperature stress and salt stress were investigated.Results and discussionIn this study, 51 U-box protein genes (PUB) were identified in the cultivated peach “SJZX” and divided into six groups. Most of the PpPUB were predicted to be located in the nucleus and chloroplasts. Promoter analyses indicated that most members may be associated with lightresponsive processes. Expression analysis based on RT-qPCR showed that most PUB members in peach were highly expressed in a certain tissues or organs. Based on the results of RT-qPCR expression analysis of 18 representative PpPUB after abiotic stress and hormone induction, all detected genes except for PpPUB19 were induced by salt stress, and PpPUB3/20/23/49 were induced by low temperature. Multiple genes were induced or repressed by exogenous hormone treatments. Furthermore, Arabidopsis seedlings heterologously overexpressing PpPUB20 exhibited greater salt tolerance than wild-type seedlings under the same salt stress conditions. These findings provide comprehensive information on the PpPUB family and identify PpPUB members that may be involved in the regulation of hormones and salt stress. Therefore, this study enhances the understanding of potential role of PpPUB in stress adaptation in peach, thereby establishing a foundation for subsequent functional investigations and applications in stress-resistant crop breeding
Preparation of Equine Immunoglobulin F(ab′) 2 against Smallpox and Evaluation of its Immunoprotective Effect
Smallpox, a severe infectious disease caused by the smallpox virus, causes a death rate as high as 30% within 15-20 days after infection. Therefore, development of anti-Smallpox product as a strategic reserve is urgently needed. We prepared and tested pepsin-digested F(ab′) 2 fragments of serum IgG from horses. Transmission electron microscopy indicated that the purified virus showed morphology consistent with VVTT. The titer was above 1.0 × 10 7 PFU/mL. The purity of the antigen exceeded 90%, according to HPLC. After purification and cleavage, the yield of the purified product F(ab′) 2 was approximately 1.3%, its purity exceeded 90%, and the neutralizing antibody titer exceeded 1:3200. F(ab′) 2 fragments had good preventive and therapeutic effects in mice at antibody doses of 5.2 mg/mL and 2.6 mg/mL. The viral loads of the drug-treated mice were suppressed to varying degrees, and the higher dose groups (5.2 and 2.6 mg/mL) showed a 2-3 fold lower viral load than that in the control group. A process for producing equine immunoglobulin F(ab′) 2 against VVTT was established. The prepared horse anti-smallpox immunoglobulin product had good neutralizing antibody effects on VVTT. The highly purified preparation may serve as a potential candidate for smallpox treatment
Prognostic Significance of Serum Cysteine-Rich Protein 61 in Patients with Acute Heart Failure
Background/Aims: Cyr61-cysteine-rich protein 61 (CCN1/CYR61) is a multifunctional matricellular protein involved in the regulation of fibrogenesis. Animal experiments have demonstrated that CCN1 can inhibit cardiac fibrosis in cardiac hypertrophy. However, no study has been conducted to assess the relation between serum CCN1 and prognosis of acute heart failure (AHF). Methods: We measured the serum CCN1 levels of 183 patients with AHF, and the patients were followed up for 6 months. The associations between CCN1 levels and some clinical covariates, especially left ventricular ejection fraction (LVEF), estimated glomerular filtration rate (eGFR), atrial fibrillation and age, were estimated. The AHF patients were followed up for 6 months. The endpoint was all-cause mortality. Kaplan-Meier curve analysis and multivariable Cox proportional hazards analysis were employed to evaluate the prognostic ability of CCN1. We used calibration, discrimination and reclassification to assess the mortality risk prediction of adding CCN1. Results: Serum CCN1 concentrations in AHF patients were significantly increased compared with those in individuals without AHF (237 pg/ml vs. 124.8 pg/ml, p< 0.001). CCN1 level was associated with the level of NT-proBNP (r=0.349, p< 0.001) and was not affected by LVEF, eGFR, age or atrial fibrillation in AHF patients. Importantly, Kaplan-Meier curve analysis illustrated that the AHF patients with serum CCN1 level > 260 pg/ ml had a lower survival rate (p< 0.001). Multivariate Cox hazard analysis suggests that CCN1 functions as an independent predictor of mortality for AHF patients (LgCCN1, hazard ratio 5.825, 95% confidence interval: 1.828-18.566, p=0.003). In addition, the inclusion of CCN1 in the model with NT-proBNP significantly improved the C-statistic for predicting death (0.758, p< 0.001). The integrated discrimination index was 0.019 (p< 0.001), and the net reclassification index increased significantly after addition of CCN1 (23.9%, p=0.0179). Conclusions: CCN1 is strongly predictive of 6-month mortality in patients with AHF, suggesting serum CCN1 as a promising candidate prognostic biomarker for AHF patients
Purified Immunoglobulin F(ab′) 2 Protects Mice and Rhesus Monkeys against Lethal Ricin Intoxication
Ricin is a highly toxic ribosome-inactivating lectin derived from castor beans. To date, no antidote is available to treat ricin-poisoned patients, and the development of a safe and effective antidote is urgently needed. First, ricin was prepared and used to construct a mouse model and a rhesus monkey model of ricin intoxication. Second, pepsin-digested F(ab′) 2 fragments of serum IgG from horses injected with Freund’s-adjuvanted purified ricin were prepared. Third, the protective efficacy was evaluated in mouse and rhesus monkey models of lethal ricin intoxication. The purity quotient of the prepared ricin and F(ab′) 2 fragments exceeded 90% and 85% in the mouse and monkey models, respectively. The LD 50 of ricin in mice and rhesus monkeys was 2.7 and 9 μg/kg, respectively. A quantity of 6.25 and 1.85 mg/kg F(ab′) 2 was sufficient to treat lethal ricin intoxication in the mice and rhesus monkeys, respectively. Finally, the effect of this therapeutic antibody on peripheral blood immune cells was examined by analysis of peripheral blood immune cells through single cell sequencing. The underlying mechanism was found to involve restraining neutrophil activation, proliferation, and differentiation. Purified F(ab′) 2 fragments administered with needle-free devices fully protect mice and rhesus monkeys against lethal doses of ricin intoxication
Design and Implementation of a TD_SCDMA Video Monitoring System Based on Android
AbstractThis paper introduces a design of a video monitoring system based on TD_SCDMA. The system is mainly composed of a video data acquisition and processing unit circuitry, a wireless module hardware circuitry and a network subsystem. The hardware design of the system is based on high performance chip 88AP310. The software design of the system is based on Android OS
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