As a new type of biodegradable implant material, zinc matrix composites have excellent potential in the application of biodegradable implants because of their better corrosion resistance than ...magnesium matrix materials. Our previous studies have shown that graphene nanosheet reinforced zinc matrix composites (Zn-GNS) prepared by spark plasma sintering (SPS) have good mechanical properties and suitable degradation rate. However, the biocompatibility of zinc matrix composites is still a problem of concern. The cytocompatibility and blood compatibility of pure zinc and Zn-GNS composites in vitro were studied. The results showed that Zn-GNS composites had acceptable toxicity to MG-63 human osteosarcoma cells. In addition, the hemolysis rate of pure zinc and its composites were less than 3%, which has no adverse effect on adhered platelets, and has good antithrombotic and antiadhesion platelets properties. In conclusion, the addition of GNS did not adversely affect the biocompatibility of Zn-GNS composites, which indicated that Zn-GNS composites are a promising candidate for bone implantation.
This work used spark plasma sintering (SPS) to prepare graphene nanosheets (GNS) reinforced zinc matrix composites. The influence of GNS on the microstructure and mechanical properties of zinc matrix ...composites was studied. The results show that the GNS/Zn composites prepared by SPS have a dense structure and good interface bonding, and GNS are uniformly distributed in the zinc matrix. Adding GNS can significantly improve the mechanical properties of the zinc matrix. When 0.7 wt% GNS are added, the comprehensive mechanical properties of the composite material are improved. The ultimate tensile strength is 254 MPa, and the Vickers hardness is 65 HV, which are 126 and 20.3% higher than those of pure zinc (112 MPa and 54 HV), respectively. The strengthening mechanisms of GNS/Zn composites are mainly load transfer of GNS and dislocation strengthening caused by coefficient of thermal expansion (CTE) mismatch. In addition, the biodegradability of GNS/Zn composites was evaluated by electrochemical measurement and immersion test. The results show that adding GNS to the zinc matrix will accelerate the degradation rate of the composite material. But the degradation rate can be controlled by the content of GNS. Its degradation rate is in the range of 69-301 μm/a, an ideal degradation rate as an orthopedic implant material.
Zinc alloy has been considered as a promising candidate for orthopedic implants due to its suitable degradation rate and good biocompatibility. However, its mechanical properties still have to be ...optimized. Metal matrix composites (MMC) are an effective way to improve the mechanical properties of zinc alloy. In this study, pure zinc as matrix, Cu-coated multiwall carbon nanotubes (MWCNTs) were used as reinforcement, and MWCNTs/Zn composites were successfully prepared by combining the use of electroless deposition (ED), spark plasma sintering (SPS), and hot-rolling techniques. The results show that MWCNTs are uniformly dispersed in the zinc matrix and a tight interface is formed between the MWCNTs and the zinc matrix. As the content of the MWCNTs increases, the mechanical properties of the MWCNTs/Zn composites gradually increase. The Cu-coated MWCNTs/Zn composites have higher mechanical properties than uncoated Cu. 3 vol% Cu-coated MWCNTs/Zn composite has a highest ultimate tensile strength of 281 MPa, but the elongation is only 4%. Load transfer effect and fine grain strengthening are two main strengthening mechanisms of MWCNTs/Zn composites. This research provides a new method for the design and preparation of MWCNTs/Zn composites.
TiO2 nanopowders and Cu-doped TiO2 were prepared by high-energy ball milling and characterized by X-ray diffraction (XRD), UV–vis diffuse reflectance (UV–vis - DRS) spectra, a scanning electron ...microscope (SEM), an energy dispersive spectrum (EDS) and an X-ray photoelectron spectrometer (XPS) to study the effect of Cu doping amount, milling time and balls-to-powder ratio on the microstructure and antimicrobial activity of the nanopowders. The results show that the mean size of the powders is reduced to below 100 nm after 3 h of milling. The prepared copper-doped TiO2 powders have excellent antibacterial activity against the Gram bacteria, which depends on the degree of copper doping.
Introduction
Integrated knowledge regarding pre‐exposure prophylaxis (PrEP) awareness and willingness to use PrEP can be useful for HIV prevention in high incidence groups. This review summarizes the ...awareness of PrEP and willingness to use PrEP among men who have sex with men (MSM).
Methods
Online electronic databases were searched before 31 August 2021. A meta‐analysis was conducted to pool studies analysing PrEP awareness and willingness to use PrEP. LOESS regression and linear regression were applied to fit the trends over time for the proportion of MSM aware of PrEP and willing to use PrEP. Dose–response meta‐analysis (DRMA) was conducted by a restricted cubic spline model to explore the relationship between willingness to use PrEP and selected factors.
Results and Discussion
A total of 156 articles involving 228,403 MSM were included. The pooled proportions of MSM aware of PrEP and willing to use PrEP were 50.0 (95% CI: 44.8–55.2) and 58.6% (95% CI: 54.8–62.4), respectively. PrEP awareness varied among countries with different economic status and different WHO regions, among different publication and research years, PrEP types and support policies. PrEP willingness differed among countries with different economic status and groups with different risks of HIV. The awareness of PrEP increased from 2007 to 2019 with a slope of 0.040260 (p<0.0001), while the proportion of MSM willing to use PrEP decreased from 2007 to 2014 (slope = –0.03647, p = 0.00390) but increased after 2014 (slope = 0.04187, p = 0.03895). The main facilitators of willingness to use PrEP were PrEP awareness, condomless sexual behaviours, high perceived risk of HIV infection and influence of social network. The main barriers were doubts about the efficacy and side effects of PrEP. DRMA results indicated that MSM with more sexual partners and lower level of education were more willing to use PrEP. No publication bias was observed.
Conclusions
The proportions of PrEP awareness and willingness to use PrEP among MSM have increased since 2014, although the awareness was low and the willingness was moderate. Improving awareness of PrEP through increasing access to PrEP‐related health education and enhancing risk perceptions of HIV infection could have positive effects on the willingness to use PrEP among MSM.
TiO2 samples doped with lithium, sodium, magnesium, iron or cobalt were prepared by high-energy ball milling for different periods of time. The crystalline phase, chemical composition, crystalline ...size and photo-absorption were characterized by X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS) and Ultraviolet visible diffuse reflectance spectroscopy (UV - Vis - DRS), Fourier transform infrared spectroscopy (FT - IR) and scanning electron microscopy (SEM). The antimicrobial properties of the modified TiO2 samples were evaluated with E. coli and S.aureus assays. The results of the XRD show that the TiOSO4, Ti3O5, Li2TiO3 and NaTi2O4 phases appear along with Li, Na and Mg doped TiO2. However, XPS spectra indicated that Ti exists as both Ti3+ and Ti4+ in Na-doped TiO2 samples. Ti3+, due to its narrow band gap, is highly active in promoting visible light-induced photocatalytic activity. SEM images showed that the crystalline size of TiO2 is reduced and has a common-round and hexagonal plate morphology after milling. The modified TiO2 samples had the best antimicrobial activities after 3h of milling. In particular, the antimicrobial rate of TiO2 5% doped with transition metals (Co, Fe) reached 100% against E. coli, but the antibacterial rate against S. aureus for Co and Fe dopants was 98.4% and 98.2%, respectively.
Gastric cancer is one of the most common causes of cancer‐related death worldwide. Immunotherapy via programmed cell death protein 1 (PD‐1)/programmed cell death‐ligand 1 (PD‐L1) blockade has shown ...benefits for gastric cancer. Epigenetic DNA methylation critically regulates cancer immune checkpoints. We investigated how the natural compound oleanolic acid (OA) affected PD‐L1 expression in gastric cancer cells. Interleukin‐1β (IL‐1β) at 20 ng/mL was used to stimulate human gastric cancer MKN‐45 cells. IL‐1β significantly increased PD‐L1 expression, which was abolished by OA. Next, OA‐treated MKN‐45 cells were co‐cultured with activated and PD‐1‐overexpressing Jurkat T cells. OA restored IL‐2 levels in the co‐culture system and increased T cell killing toward MKN‐45 cells. Overexpression of PD‐L1 eliminated OA‐enhanced T cell killing capacity; however, PD‐1 blocking antibody abrogated the cytotoxicity of T cells. Moreover, OA abolished IL‐1β‐increased DNA demethylase activity in MKN‐45 cells. DNA methyltransferase inhibitor 5‐azacytidine rescued OA‐reduced PD‐L1 expression; whereas DNA demethylation inhibitor gemcitabine inhibited PD‐L1 expression, and, in combination with OA, provided more potent inhibitory effects. Furthermore, OA selectively reduced the expression of DNA demethylase TET3 in IL‐1β‐treated MKN‐45 cells, and overexpression of TET3 restored OA‐reduced PD‐L1 expression. Finally, OA disrupted nuclear factor κB (NF‐κB) signaling IL‐1β‐treated MKN‐45 cells, and overexpression of NF‐κB restored OA downregulation of TET3 and PD‐L1. The cytotoxicity of T cells toward MKN‐45 cells was also weakened by NF‐κB overexpression. Altogether, OA blocked the IL‐1β/NF‐κB/TET3 axis in gastric cancer cells, leading to DNA hypomethylation and downregulation of PD‐L1. Our discoveries suggested OA as an epigenetic modulator for immunotherapy or an adjuvant therapy against gastric cancer.
Introduction: Integrated knowledge regarding pre-exposure prophylaxis (PrEP) awareness and willingness to use PrEP can be useful for HIV prevention in high incidence groups. This review summarizes ...the awareness of PrEP and willingness to use PrEP among men who have sex with men (MSM). Methods: Online electronic databases were searched before 31 August 2021. A meta-analysis was conducted to pool studies analysing PrEP awareness and willingness to use PrEP. LOESS regression and linear regression were applied to fit the trends over time for the proportion of MSM aware of PrEP and willing to use PrEP. Dose-response meta-analysis (DRMA) was conducted by a restricted cubic spline model to explore the relationship between willingness to use PrEP and selected factors. Results and Discussion: A totalof 156 articles involving 228,403 MSM were included. The pooled proportions of MSM aware of PrEP and willing to use PrEP were 50.0 (95% CI: 44.8-55.2) and 58.6% (95% CI: 54.8-62.4), respectively. PrEP awareness varied among countries with different economic status and different WHO regions, among different publication and research years, PrEP types and support policies. PrEP willingness differed among countries with different economic status and groups with different risks of HIV The awareness of PrEP increased from 2007 to 2019 with a slope of 0.040260 (p<0.0001), while the proportion of MSM willing to use PrEP decreased from 2007 to 2014 (slope = -0.03647, p = 0.00390) but increased after 2014 (slope = 0.04187, p = 0.03895). The main facilitators of willingness to use PrEP were PrEP awareness, condomless sexual behaviours, high perceived risk of HIV infection and influence of social network. The main barriers were doubts about the efficacy and side effects of PrEP. DRMA results indicated that MSM with more sexual partners and lower level of education were more willing to use PrEP. No publication bias was observed. Conclusions: The proportions of PrEP awareness and willingness to use PrEP among MSM have increased since 2014, although the awareness was low and the willingness was moderate. Improving awareness of PrEP through increasing access to PrEP-related health education and enhancing risk perceptions of HIV infection could have positive effects on the willingness to use PrEP among MSM. Keywords: men who have sex with men; pre-exposure prophylaxis; awareness; willingness; trend; meta-analysis Additional information may be found under the Supporting Information tab of this article.
DNA sequences have the fundamental information for each species and a comparison between DNA sequences is one of the basic biological problems. There are a large number of algorithms applying in ...sequence alignment. Some are for approximate alignment, and others are for exact alignment, which also plays an important role in biology research. In this paper, a new parallel algorithm based on FED algorithm for exact sequences alignment with MPI is proposed. The experimental results indicate that the proposed algorithm can report the matched positions in the specific sequence and improve the matching speed with MPI, as well as reduce the storage requirement.
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