Two main explanations exist for the deformation mechanisms in Ti-Nb-based gum metals, i.e. the formation of reversible nanodisturbance and reversible stress-induced martensitic transformation. In ...this work, we used the in situ synchrotron-based high-energy X-ray diffuse-scattering technique to reveal the existence of a specific deformation mechanism, i.e. deformation-induced spatially confined martensitic transformations, in Ti-24Nb-4Zr-8Sn-0.10O single crystals with cubic beta parent phase, which explains well some anomalous mechanical properties of the alloy such as low elastic modulus and nonlinear superelasticity. Two kinds of nanosized martensites with different crystal structures were found during uniaxial tensile loading along the 110 beta axis at room temperature and 190K, respectively. The detailed changes in the martensitic phase transformation characteristics and the transformation kinetics were experimentally observed at different temperatures. The domain switch from non-modulated martensite to a modulated one occurred at 190K, with its physical origin attributed to the heterogeneity of local phonon softening depending on temperature and inhomogeneous composition in the parent phase. An in-depth understanding of the formation of stress-induced spatially confined nanosized martensites with a large gradient in chemical composition may benefit designs of high-strength and high-ductility alloys.
Element doping is recognized as a powerful way to modify surface defect structure and further enhance the fluorescence performance of graphene quantum dots (GQDs). N-doped, S-doped and S, N co-doped ...GQDs were synthesized to explore the influence of element doping on fluorescence sensing of dopamine (DA) biomolecules. Two interesting works are found, one is that the N-doped GQDs with urea as N source are more effective than the S-doped and S,N co-doped GQDs, characterized by the higher quantum yield (QY) up to 78% and sensitive fluorescence quenching performance to DA. The other is that the N-doped GQDs with ethylenediamine as N source have the highest QY up to 95%, however, exhibits no quenching performance to DA. This abnormal observation is discussed based on the microstructure analysis. Under the optimal reaction condition, the N-doped GQDs exhibit a dual linear relationship of quenching intensity with DA concentration in the range of 10–3000 nM and 3000–7000 nM with detection limits of 3.3 and 611 nM, respectively. The quenching mechanism of N-doped GQDs toward DA is explored from the view of N chemical states, biomolecule structure of DA homologues and redox reaction of DA.
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•N-doped, S-doped and S, N co-doped quantum dots (GQDs) were synthesized.•Doping effect on fluorescence sensing of GQDs to dopamine (DA) is discussed.•N-doped GQDs by urea can enhance the quantum yield and sensing performance.•A dual linearity is observed and the lowest detection limit is 3.3 nM.•The quenching mechanism of N-doped GQDs toward DA is explored.
Materials that undergo a reversible change of crystal structure through martensitic transformation （MT） possess unusual functionalities including shape memory, superelasticity, and low/negative ...thermal ex- pansion. These properties have many advanced applications, such as actuators, sensors, and energy conversion, but are limited typically in a narrow temperature range of tens of Kelvin. Here we report that, by creating a nano-scale concentration modulation via phase separation, the MT can be rendered continuous by an in-situ elastic confinement mechanism. Through a model titanium alloy, we demon- strate that the elastically confined continuous MT has unprecedented properties, such as superelasticity from below 4.2 K to 500 K, fully tunable and stable thermal expansion, from positive, through zero, to negative, from below 4.2 K to 573 K, and high strength-to-modulus ratio across a wide temperature range. The elastic tuning on the MT, together with a significant extension of the crystal stability limit, provides new opportunities to explore advanced materials.
Summary
The aim was to meta-analyze randomized controlled trials of calcium plus vitamin D supplementation and fracture prevention. Meta-analysis showed a significant 15 % reduced risk of total ...fractures (summary relative risk estimate SRRE, 0.85; 95 % confidence interval CI, 0.73–0.98) and a 30 % reduced risk of hip fractures (SRRE, 0.70; 95 % CI, 0.56–0.87).
Introduction
Calcium plus vitamin D supplementation has been widely recommended to prevent osteoporosis and subsequent fractures; however, considerable controversy exists regarding the association of such supplementation and fracture risk. The aim was to conduct a meta-analysis of randomized controlled trials RCTs of calcium plus vitamin D supplementation and fracture prevention in adults.
Methods
A PubMed literature search was conducted for the period from July 1, 2011 through July 31, 2015. RCTs reporting the effect of calcium plus vitamin D supplementation on fracture incidence were selected from English-language studies. Qualitative and quantitative information was extracted; random-effects meta-analyses were conducted to generate summary relative risk estimates (SRREs) for total and hip fractures. Statistical heterogeneity was assessed using Cochran’s
Q
test and the
I
2
statistic, and potential for publication bias was assessed.
Results
Of the citations retrieved, eight studies including 30,970 participants met criteria for inclusion in the primary analysis, reporting 195 hip fractures and 2231 total fractures. Meta-analysis of all studies showed that calcium plus vitamin D supplementation produced a statistically significant 15 % reduced risk of total fractures (SRRE, 0.85; 95 % confidence interval CI, 0.73–0.98) and a 30 % reduced risk of hip fractures (SRRE, 0.70; 95 % CI, 0.56–0.87). Numerous sensitivity and subgroup analyses produced similar summary associations. A limitation is that this study utilized data from subgroup analysis of the Women’s Health Initiative.
Conclusions
This meta-analysis of RCTs supports the use of calcium plus vitamin D supplements as an intervention for fracture risk reduction in both community-dwelling and institutionalized middle-aged to older adults.
•We combine environmental and safety factors in SBM model to assess transport sustainability.•We apply the model to OECD countries and study the factors behind their performance.•Joint assessment of ...environmental and safety factors yields different results from separate assessment.•Sustainable transport is affected by socio-economic factors, i.e., income, urbanization and governance.
Environment and safety are two pillars of sustainable transport. Unlike existing studies that assess environmental impacts and safety concerns separately, in this paper we intend to capture the multifaceted nature of sustainable transport by combining environmental and safety factors. We formulate a unified performance measure using data envelopment analysis (DEA), a nonparametric method for benchmarking entities with multiple inputs and multiple outputs. In this method, environmental impacts (e.g., particulate matter and carbon dioxide emissions) and safety concerns (e.g., deaths and injuries in accidents) are treated as undesirable outputs under the slacks-based measure (SBM). We apply the model to conduct a joint assessment of environmental impacts and safety concerns of road transport for a group of OECD countries over the period 2000–2014. We show that the unified measure from joint assessment can be drastically different from that of assessing environment and safety separately. Furthermore, we investigate the relationship between the assessment results and socio-economic factors, and find that disposable income, governance quality and urbanization are significantly associated with the level of transport sustainability.
Background
The prevalence of allergic rhinitis (AR) has increased worldwide in recent decades. This study was conducted to investigate the prevalence of self‐reported AR and profiles of AR‐related ...comorbidities in the adult population of China over time.
Methods
This study surveyed residents of 18 major cities in mainland China. Telephone interviews were conducted with study participants after sampling target telephone numbers by random digit dialing. The questions asked during telephone interviews were based on those included in validated questionnaires and focused on topics regarding AR, nonallergic rhinitis (NAR), acute/chronic rhinosinusitis (ARS/CRS), asthma, and atopic dermatitis (AD).
Results
During 2011, a total of 47 216 telephone interviews were conducted, and the overall response rate was 77.5%. When compared with the AR prevalence in 11 cities surveyed in 2005, there was a significant increase in self‐reported adult AR in eight of those cities (P < 0.01). In 2011, the standardized prevalence of self‐reported adult AR in the 18 cities was 17.6%. The concentration of SO2 was positively correlated with the prevalence of AR (r = 0.504, P = 0.033). A multiple regression model showed that the absolute change in household yearly income was significantly associated with the change in the prevalence of AR (R2 = 0.68), after adjusting for PM10, SO2, NO2, temperature, and humidity. The overall prevalences of NAR, ARS, CRS, asthma, and AD in the general population were 16.4%, 5.4%, 2.1%, 5.8%, and 14%, respectively.
Conclusion
During a 6‐year period, there was a significant increase in the prevalence of self‐reported AR in the general Chinese adult population. The incidence of AR being accompanied by rhinosinusitis, asthma, or AD was significantly higher among individuals having self‐reported AR compared with the general population.
Various factors and cellular components in the tumor microenvironment are key drivers associated with drug resistance in many cancers. Here, we analyzed the factors and molecular mechanisms involved ...in chemoresistance in patients with esophageal squamous cell carcinoma (ESCC). We found that interleukin 6 (IL6) derived mainly from cancer-associated fibroblasts played the most important role in chemoresistance by upregulating C-X-C motif chemokine receptor 7 (CXCR7) expression through signal transducer and activator of transcription 3/nuclear factor-κB pathway. CXCR7 knockdown resulted in the inhibition of IL6-induced proliferation and chemoresistance. In addition, CXCR7 silencing significantly decreased gene expression associated with stemness, chemoresistance and epithelial-mesenchymal transition and suppressed the proliferation ability of ESCC cells in three-dimensional culture systems and angiogenesis assay. In clinical samples, ESCC patients with high expression of CXCR7 and IL6 presented a significantly worse overall survival and progression-free survival upon receiving cisplatin after operation. These results suggest that the IL6-CXCR7 axis may provide a promising target for the treatment of ESCC.
Understanding transporter-mediated drug–drug interactions (DDIs) for investigational agents is important during drug development to assess DDI liability, its clinical relevance, and to determine ...appropriate DDI management strategies. P-glycoprotein (P-gp) is an efflux transporter that influences the pharmacokinetics (PK) of various compounds. Assessing transporter induction in vitro is challenging and is not always predictive of in vivo effects, and hence there is a need to consider clinical DDI studies; however, there is no clear guidance on when clinical evaluation of transporter induction is required. Furthermore, there is no proposed list of index transporter inducers to be used in clinical studies. This review evaluated DDI studies with known P-gp inducers to better understand the mechanism and site of P-gp induction, as well as the magnitude of induction effect on the exposure of P-gp substrates. Our review indicates that P-gp and cytochrome P450 (CYP450) enzymes are co-regulated via the pregnane xenobiotic receptor (PXR) and the constitutive androstane receptor (CAR). The magnitude of the decrease in substrate drug exposure by P-gp induction is generally less than that of CYP3A. Most P-gp inducers reduced total bioavailability with a minor impact on renal clearance, despite known expression of P-gp at the apical membrane of the kidney proximal tubules. Rifampin is the most potent P-gp inducer, resulting in an average reduction in substrate exposure ranging between 20 and 67%. For other inducers, the reduction in P-gp substrate exposure ranged from 12 to 42%. A lower reduction in exposure of the P-gp substrate was observed with a lower dose of the inducer and/or if the administration of the inducer and substrate was simultaneous, i.e. not staggered. These findings suggest that clinical evaluation of the impact of P-gp inducers on the PK of investigational agents that are substrates for P-gp might be warranted only for compounds with a relatively steep exposure–efficacy relationship.
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