Highly photoluminescent MoOx quantum dots: Facile synthesis and application in off-on Pi sensing in lake water samples

Molybdenum oxide (MoO_x) is a well-studied transition-metal semiconductor material, and has a wider band gap than MoS₂ which makes it become a promising versatile probe in a variety of fields, such as gas sensor, catalysis, energy storage ect. However, few MoO_x nanomaterials possessing photoluminescence have been reported until now, not to mention the application as photoluminescent probes. Herein, a one-pot method is developed for facile synthesis of highly photoluminescent MoO_x quantum dots (MoO_x QDs) in which commercial molybdenum disulfide powder and hydrogen peroxide (H₂O₂) are involved as the precursor and oxidant, respectively. Compared with current synthesis methods, the proposed one has the advantages of rapid, one-pot, easily prepared, environment friendly as well as strong photoluminescence. The obtained MoO_x QDs is further utilized as an efficient photoluminescent probe, and a new off-on sensor has been constructed for phosphate (Pi) determination in complicated lake water samples, attributed to the fact that the binding affinity of Eu³⁺ ions to the oxygen atoms from Pi is much higher than that from the surface of MoO_x QDs. Under the optimal conditions, a good linear relationship was found between the enhanced photoluminescence intensity and Pi concentration in the range of 0.1–160.0 μM with the detection limit of 56 nM (3σ/k). The first application of the photoluminescent MoO_x nanomaterials for ion photochemical sensing will open the gate of employing MoO_x nanomaterials as versatile probes in a variety of fields, such as chemi-/bio-sensor, cell imaging, biomedical and so on.     

氢化松香及其衍生物的制备研究进展

氢化松香是重要的天然可再生资源松香的深加工产品之一,在电子、食品、医药等领域有着重要的用途。本文介绍了氢化松香的主要组分、氢化松香国内外工业化生产历程及氢化松香制备工艺,特别是由贵金属钯和非贵金属镍为催化剂的制备工艺的研究现状;对近年来氢化松香和二氢枞酸衍生物,主要是以氢化松香为整体的衍生物的制备研究进行了综述,并对氢化松香及其衍生物研究前景进行了展望。     

Group-wise sufficient dimension reduction with principal fitted components

Sufficient dimension reduction methodologies in regressions of Y on a p-variate X aim at obtaining a reduction \(R(X) \in {\mathbb R}^{d}, d \le p\), that retains all the regression information of Y in X. When the predictors fall naturally into a number of known groups or domains, it has been established that exploiting the grouping information often leads to more effective sufficient dimension reduction of the predictors. In this article, we consider group-wise sufficient dimension reduction based on principal fitted components, when the grouping information is unknown. Principal fitted components methodology is coupled with an agglomerative clustering procedure to identify a suitable grouping structure. Simulations and real data analysis demonstrate that the group-wise principal fitted components sufficient dimension reduction is superior to the standard principal fitted components and to general sufficient dimension reduction methods.     

High-throughput miniaturized microfluidic microscopy with radially parallelized channel geometry

In this article, we present a novel approach to throughput enhancement in miniaturized microfluidic microscopy systems. Using the presented approach, we demonstrate an inexpensive yet high-throughput analytical instrument. Using the high-throughput analytical instrument, we have been able to achieve about 125,880 cells per minute (more than one hundred and twenty five thousand cells per minute), even while employing cost-effective low frame rate cameras (120 fps). The throughput achieved here is a notable progression in the field of diagnostics as it enables rapid quantitative testing and analysis. We demonstrate the applicability of the instrument to point-of-care diagnostics, by performing blood cell counting. We report a comparative analysis between the counts (in cells per μl) obtained from our instrument, with that of a commercially available hematology analyzer.     

双反射膜双频He-Ne激光器双频特性及偏振特性的实验研究

本文对 5 MHz频差双反射膜双频 He- Ne激光器输出激光的双频特性及偏振特性进行了实验研究。研究结果表明 ,当磁场方向同反射膜的一个本征模方向基本重合时 ,有双频出现 ;当磁场方向同反射膜的一个本征模方向夹角在 45°左右时 ,无双频出现。输出激光的偏振方向由反射膜的本征模确定 ,其偏振非正交程度为 tgρ≤ 0 .0 0 87,椭圆化程度tgβ随激光管与磁场的相对角位置变化而发生变化。在合适的位置 ,tgβ可以小至 2 / 70 0。该种外差光源具有较好的偏振特性。     

Leveraging an enzyme/artificial substrate system to enhance cellular persulfides and mitigate neuroinflammation

Persulfides and polysulfides, collectively known as the sulfane sulfur pool along with hydrogen sulfide (H₂S), play a central role in cellular physiology and disease. Exogenously enhancing these species in cells is an emerging therapeutic paradigm for mitigating oxidative stress and inflammation that are associated with several diseases. In this study, we present a unique approach of using the cell''s own enzyme machinery coupled with an array of artificial substrates to enhance the cellular sulfane sulfur pool. We report the synthesis and validation of artificial/unnatural substrates specific for 3-mercaptopyruvate sulfurtransferase (3-MST), an important enzyme that contributes to sulfur trafficking in cells. We demonstrate that these artificial substrates generate persulfides in vitro as well as mediate sulfur transfer to low molecular weight thiols and to cysteine-containing proteins. A nearly 100-fold difference in the rates of H₂S production for the various substrates is observed supporting the tunability of persulfide generation by the 3-MST enzyme/artificial substrate system. Next, we show that the substrate 1a permeates cells and is selectively turned over by 3-MST to generate 3-MST-persulfide, which protects against reactive oxygen species-induced lethality. Lastly, in a mouse model, 1a is found to significantly mitigate neuroinflammation in the brain tissue. Together, the approach that we have developed allows for the on-demand generation of persulfides in vitro and in vivo using a range of shelf-stable, artificial substrates of 3-MST, while opening up possibilities of harnessing these molecules for therapeutic applications.

A persulfide/hydrogen sulfide generation strategy through artificial substrates for 3-mercaptopyruvate sulfurtransferase (3-MST) is reported, which enhances cellular persulfides, attenuates reactive oxygen species (ROS), and alleviates inflammation.     

Linearly polarized ultraviolet photoreaction of photocrosslinkable polymers comprising the p-phenylenediacrylate group and photoalignment control of liquid crystals on the resultant film

We present (1) the linearly polarized (LP) ultraviolet (UV) photoreaction of block copolyesterethers comprising a hard segment of polyester and soft segment of poly(tetramethylene ether) (PTMG) and (2) the alignment behavior of liquid crystals (LCs) on the resultant photoreacted polymer films. Two kinds of copolyesterethers with different polyester segments of poly(hexamethylene p-phenylenediacrylate) (1a) or poly(hexamethylene p-phenylenediacrylate)-co-poly(hexamethylene 1,4-dibenzoate) (1b) were used in this study. The LP–UV irradiation resulted in a negative optical anisotropy for both polymer films, and a homogeneous photoalignment of LCs was achieved on the photoreacted polymer film. The LC alignment was perpendicular to the electric vector of the incident polarized light for 1a, whereas a reversion of the alignment from parallel to perpendicular was observed for 1b, depending on the irradiation doses. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4000–4006, 1999     

实验优化设计Sr_2MgSi_2O_7:Eu~(2+),Dy~(3+)的合成及长余辉特性

为了得到最长有效余辉时间的Sr_2MgSi_2O_7:Eu~(2+),Dy~(3+)荧光粉,应用二次通用旋转组合设计对实验进行全程优化,建立了稀土离子掺杂浓度Eu~(2+),Dy~(3+)和有效余辉时间的二元二次回归方程模型,应用遗传算法计算得到有效余辉时间的理论最大值.采用高温固相法合成了最优掺杂浓度Sr_2MgSi_2O_7:0.5mol%Eu~(2+),1.0mol%Dy~(3+)的荧光粉,在370nm激发下观察到了465nm的特征发射,这归因于Eu~(2+)的4f65d1—4f7跃迁.测量了最优荧光粉的热释发光特性,计算得到了陷阱深度为0.688eV,讨论了长余辉发光的特性.