Syntheses and characterization of two oxoborates, (Pb3O)2(BO3)2MO4 (M=Cr, Mo)

Two oxoborates, (Pb₃O)₂(BO₃)₂MO₄ (M=Cr, Mo), have been prepared by solid-state reactions below 700 °C. Single-crystal XRD analyses showed that the Cr compound crystallizes in the orthorhombic group Pnma with a=6.4160(13) Å, b=11.635(2) Å, c=18.164(4) Å, Z=4 and the Mo analog in the group Cmcm with a=18.446(4) Å, b=6.3557(13) Å, c=11.657(2) Å, Z=4. Both compounds are characterized by one-dimensional chains formed by corner-sharing OPb₄ tetrahedra. BO₃ and CrO₄ (MoO₄) groups are located around the chains to hold them together via Pb–O bonds. The IR spectra further confirmed the presence of BO₃ groups in both structures and UV–vis diffuse reflectance spectra showed band gaps of about 1.8 and 2.9 eV for the Cr and Mo compounds, respectively. Band structure calculations indicated that (Pb₃O)₂(BO₃)₂MoO₄ is a direct semiconductor with the calculated energy gap of about 2.4 eV.     

A new phenylethanoid glycoside from Rabdosia lophanthoides （Buch.-Ham.ex D.Don） Hara.

A new phenylethanoid glycoside,3-hydroxy-4-methoxy-β-phenylethoxy-O-α-L-rhamnopyranosyl-(1→3)-2-O-acetyl-O-β-D-glucopyranoside, named lophanthoside A,was isolated from Rabdosia lophanthoides(Buch.-Ham.ex D.Don) Hara.Its structure was determined by spectroscopic evidences.     

气质联用法测定复合食品包装袋中的二氨基甲苯

建立复合食品包装袋中二氨基甲苯气相色谱一质谱测定方法.样品用4%乙酸提取,加三氟乙酸酐进行衍生化,用气相色谱-质谱联用仪测定.二氨基甲苯含量在0. 002～0. 05μg/mL范围内与离子蜂面积呈良好的线性关系,相关系数r=0. 9998,检出限低于0. 0004 mg/L.测定结果的相对标准偏差为2. 98%～5. 50%(n=6),加标回收率为82%～92%.该方法快速、灵敏、测定结果准确.     

Excess of a class of g-frames

In this paper, we study the relationship between frames for the super Hilbert space H⊕H and g-frames for H with respect to C². We show that a g-frame associated with a frame for H⊕H remains a g-frame whenever any one of its elements is removed. Furthermore, we show that the excess of such a g-frame is at least dimH.     

Packing circuits in matroids

The purpose of this paper is to characterize all matroids M that satisfy the following minimax relation: for any nonnegative integral weight function w defined on E(M),

Simultaneous determination of 103 pesticide residues in tea samples by LC‐MS/MS

A simple and sensitive method was developed and validated for the simultaneous determination of 103 pesticide residues in tea by LC‐MS/MS. For the analysis of the pesticide with polarity, thermal lability or low volatility, this LC‐MS/MS method has an advantage over GC. In this work, residual pesticides were extracted from the tea sample with ACN and then purified using Carb‐NH₂ SPE cartridges. Using the multiple reaction monitoring mode, the pesticides were quantified and identified by the most abundant and characteristic fragment ions. The recoveries obtained for each pesticide ranged between 65 and 114% at three spiked concentration levels. The intra‐day precisions were lower than 19.6%. Good linear relationships were observed with the correlation coefficients r² >0.996 for all analytes. The established method was successfully applied to the determination of pesticide residues in real tea samples.     

Graphene nanoribbon-based supramolecular ensembles with dual-receptor targeting function for targeted photothermal tumor therapy

Triple negative breast cancer (TNBC) is one of the most malignant subtypes of breast cancer. Here, we report the construction of graphene nanoribbon (GNR)-based supramolecular ensembles with dual-receptor (mannose and α_vβ₃ integrin receptors) targeting function, denoted as GNR-Man/PRGD, for targeted photothermal treatment (PTT) of TNBC. The GNR-Man/PRGD ensembles were constructed through the solution-based self-assembly of mannose-grafted GNRs (GNR-Man) with a pyrene-tagged α_vβ₃ integrin ligand (PRGD). Enhanced PTT efficacies were achieved both in vitro and in vivo compared to that of the non-targeting equivalents. Tumor-bearing live mice were administered (tail vein) with GNR-Man/PRGD and then each mice group was subjected to PTT. Remarkably, GNR-Man/PRGD induced complete ablation of the solid tumors, and no tumor regrowth was observed over a period of 15 days. This study demonstrates a new and promising platform for the development of photothermal nanomaterials for targeted tumor therapy.

Dual receptor-targeting supramolecular glycomaterials are constructed based on graphene nanoribbons for the targeted photothermal therapy of triple-negative breast cancer in vivo.     

Tm3+离子在钨酸锌单晶中的光谱特征

采用丘克拉斯基法生长出一系列ZnWO4:Tm3 单晶 ,Tm3 浓度x =0 1 ,0 3,0 5 ,0 7和 1 0mol%。用 80 7nmLD激发 ,观察到 4 86和 6 95nm的上转换发光 ,分别相应于 1 G4→ 3 H6和3 F3 → 3 H6的跃迁 ,发光强度与泵浦光功率成双对数关系 ,其指数分别为 0 8和 1 1次方关系。     

结霜工况下重力供液与直接膨胀供液制冷系统运行特性

以R404A为工质,用热平衡法测试结霜工况下直接膨胀供液制冷系统以及重力供液制冷系统在不同蒸发器供液高度时的系统的运行特性,并进行比较。研究表明:在重力供液制冷系统中,蒸发温度和压力高于直接膨胀供液制冷系统,且受供液高度和环境温度影响;在不同供液高度时,重力供液制冷系统压缩机吸气压力高于直接膨胀供液制冷系统压缩机吸气压力,供液高度的增加,吸气压力升高,压缩机的排气压力的变化趋势与蒸发压力相似;重力供液制冷系统制冷量高于直接膨胀供液制冷系统制冷量,且随蒸发温度升高而增大,但制冷量的增加幅度却有着相反的变化趋势。供液高度为1200mm时,制冷量最大增幅达到35.59%;重力供液制冷系统COP大于直接膨胀供液制冷系统COP,重力供液制冷系统存在最佳供液高度。     

Nonlinear optical properties of Cu nanocluster composite fabricated by 180 keV ion implantation

Metal nanocluster composite glass prepared by 180 keV Cu ions into silica with dose of 5×10¹⁶ ions/cm² has been studied. The microstructural properties of the nanoclusters has been verified by optical absorption spectra and transmission electron microscopy (TEM). Third-order nonlinear optical properties of the nanoclusters were measured at 1064 and 532 nm excitations using Z-scan technique. The nonlinear refraction index, nonlinear absorption coefficient, and the real and imaginary parts of the third-order nonlinear susceptibility were deduced. Results of the investigation of nonlinear refraction by the off-axis Z-scan configuration were presented and the mechanisms responsible for the nonlinear response were discussed. Third-order nonlinear susceptibility χ⁽³⁾ of this kind of sample was determined to be 8.7×10⁻⁸ esu at 532 nm and 6.0×10⁻⁸ esu at 1064 nm, respectively.