HG-AFS测定西藏日多温泉水中砷的形态

本文采用氢化物发生-原子荧光光谱法(HG-AFS)测定温泉水中砷的形态,重点研究了西藏温泉水中砷的存在形态,发现水中除常见的砷酸盐[砷(Ⅴ)]、亚砷酸盐[砷(Ⅲ)]和有机砷外,还存在悬浮态砷。实验结果表明,西藏温泉水中砷的形态分布呈现出五价砷>三价砷>悬浮态砷>有机砷的特征,讨论了各形态态砷的相互影响因素,为进一步开发利用西藏温泉提供了科学依据。     

Coagulation behaviors and in-situ flocs characteristics of composite coagulants in cyanide-containing wastewater: Role of cationic polyelectrolyte

In this paper,composite coagulants(PFS,PFSC05,PFSC1 and PFSC5),prepared by mixing polyferric sulfate(PFS)and cationic polyelectrolyte(CP)coagulants with different weight percent(Wp)of CP(Wp=0%,0.5%,1%and 5%,respectively),were adopted to treat cyanide-containing wastewater.PFSC5 exhibited superior coagulation performances at optimal conditions:the removal of total cyanide(TCN)and chemical oxygen demand(COD)was 95%–97%and 50%–55%,respectively.The effects of CP on the properties and structure of flocs were investigated by laser diffraction instrument and small-angle laser light scattering(SALLS),respectively.The results show that the flocs of PFSC5 have higher growth rate,higher strength factor and lower recovery factor than other flocs.They are also much denser and more uniform owing to the higher fractal dimension(Df)and less microflocs(10–100 m).Furthermore,the dense structure of the PFSC5 flocs can be restored after shear and is more resistant to hydraulic conditions.Particularly,detailed morphology evolution of the flocs was in-situ detected by on-line particle imaging.Due to strong ionic strength in wastewater,the CP in PFSC5 plays a significant role of adsorption,while the main mechanism of CP is electrostatic patch aggregation during the PFSC05 systems.     

Trigonal‐Bipyramidal and Square‐Pyramidal Chromium?Manganese Chalcogenide Clusters, [E2CrMn2(CO)n]2− (E=S,Se, Te; n=9, 10): Synthesis,Electrochemistry, UV/Vis Absorption,and Computational Studies

The reactions of E powder (E=S, Se) with a mixture of Cr(CO)₆ and Mn₂(CO)₁₀ in concentrated solutions of KOH/MeOH produced two new mixed Cr? Mn? carbonyl clusters, [E₂CrMn₂(CO)₉]^2? (E=S, 1 ; Se, 2 ). Clusters 1 and 2 were isostructural with one another and each displayed a trigonal‐bipyramidal structure, with the CrMn₂ triangle axially capped by two μ₃‐E atoms. The analogous telluride cluster, [Te₂CrMn₂(CO)₉]^2? ( 3 ), was obtained from the ring‐closure of Te₂Mn₂ ring complex [Te₂Mn₂Cr₂(CO)₁₈]^2? ( 4 ). Upon bubbling with CO, clusters 2 and 3 were readily converted into square‐pyramidal clusters, [E₂CrMn₂(CO)₁₀]^2? (E=Se, 5 ; Te, 6 ), accompanied with the cleavage of one Cr? Mn bond. According to SQUID analysis, cluster 6 was paramagnetic, with S=1 at room temperature; however, the Se analogue ( 5 ) was spectroscopically proposed to be diamagnetic, as verified by TD‐DFT calculations. Cluster 6 could be further carbonylated, with cleavage of the Mn? Mn bond to produce a new arachno‐cluster, [Te₂CrMn₂(CO)₁₁]^2? ( 7 ). The formation and structural isomers, as well as electrochemistry and UV/Vis absorption, of these clusters were also elucidated by DFT calculations.     

Zinc Porphyrins with a Pyridine‐Ring‐Anchoring Group for Dye‐Sensitized Solar Cells

Anchoring groups are extremely important in controlling the performance of dye‐sensitized solar cells (DSCs). The design and characterization of sensitizers with new anchoring groups, in particular non‐carboxylic acid groups, has become a recent focus of DSC research. Herein, new donor? π? acceptor zinc? porphyrin dyes with a pyridine ring as an anchoring group have been designed and synthesized for applications in DSCs. Photophysical and electrochemical investigations demonstrated that the pyridine ring worked effectively as an anchoring group for the porphyrin sensitizers. DSCs that were based on these new porphyrins showed an overall power‐conversion efficiency of about 4.0 % under full sunlight (AM 1.5G, 100 mW cm^?2).     

Ligand‐Functionalization of BPEI‐Coated YVO4:Bi3+,Eu3+ Nanophosphors for Tumor‐Cell‐Targeted Imaging Applications

In this study, surface‐functionalized, branched polyethylenimine (BPEI)‐modified YVO₄:Bi³⁺,Eu³⁺ nanocrystals (NCs) were successfully synthesized by a simple, rapid, solvent‐free hydrothermal method. The BPEI‐coated YVO₄:Bi³⁺,Eu³⁺ NCs with high crystallinity show broad‐band excitation in the λ=250 to 400 nm near‐ultraviolet (NUV) region and exhibit a sharp‐line emission band centered at λ=619 nm under excitation at λ=350 nm. The surface amino groups contributed by the capping agent, BPEI, not only improve the dispersibility and water/buffer stability of the BPEI‐coated YVO₄:Bi³⁺,Eu³⁺ NCs, but also provide a capability for specifically targeted biomolecule conjugation. Folic acid (FA) and epidermal growth factor (EGF) were further attached to the BPEI‐coated YVO₄:Bi³⁺,Eu³⁺ NCs and exhibited effective positioning of fluorescent NCs toward the targeted folate receptor overexpressed in HeLa cells or EGFR overexpressed in A431 cells with low cytotoxicity. These results demonstrate that the ligand‐functionalized, BPEI‐coated YVO₄:Bi³⁺, Eu³⁺ NCs show great potential as a new‐generation biological luminescent bioprobe for bioimaging applications. Moreover, the unique luminescence properties of BPEI‐coated YVO₄:Bi³⁺,Eu³⁺ NCs show potential to combine with a UVA photosensitizing drug to produce both detective and therapeutic effects for human skin cancer therapy.     

Highly selective synthesis of single-walled carbon nanotubes from methane in a coupled Downer-turbulent fluidized-bed reactor

For the synthesis of single-walled carbon nanotubes (SWCNTs) from CH₄ over a Fe/MgO catalyst, we proposed a coupled Downer-turbulent fluidized-bed (TFB) reactor to enhance the selectivity and yield (or production rate) of SWCNTs. By controlling a very short catalyst residence time (1–3 s) in the Downer, only part of Fe oxides can be reduced to form Fe nano particles (NPs) available for the growth of SWCNTs. The percentage of unreduced Fe oxides increased and the yield of SWCNTs decreased accordingly with the increase of catalyst feeding rate in Downer. SWCNTs were preferentially grown on the catalyst surface and inhibited the sintering of the Fe crystallites which would be formed thereafter in the downstream TFB, evidenced by TEM, Raman and TGA. The coupled Downer-turbulent fluidized-bed reactor technology allowed higher selectivity and higher production rate of SWCNTs as compared to TFB alone.     

Self-assembly of coil-rod-coil molecules into bicontinuous cubic and oblique columnar assemblies depending on coil chain length

Coil-rod-coil molecules 1–3, consisting of four biphenyls and a p-terphenyl unit linked together with ether bonds as a rod segment and poly(propylene oxide) (PPO) with a degree of polymerization (DP) of 7, 12, 17 as coil segments were synthesized. These molecules contain lateral methyl groups at 2 and 5 positions of the middle benzene ring of p-terphenyl. The self-assembling behavior of molecules 1–3 was investigated by means of DSC, POM and SAXS in the bulk state. Molecule 1 self-organizes into a lamellar structure in the bulk state and transfers into a bicontinuous cubic structure in the liquid crystalline phase. While, molecules 2, 3 containing longer coil chains than 1 self-assemble into the hexagonal perforated lamellar (HPL) structures and the oblique columnar structures in the solid state and liquid crystalline phase, respectively. These results reveal that self-organizing behavior of such molecules is dramatically influenced by the length of the coil chains connected with the rod building block, as well as the lateral methyl groups incorporating in the middle of the rod segment.     

Determination of Diuretics in Urine Using Immobilized Multi‐Walled Carbon Nanotubes in Hollow Fiber Liquid‐Phase Microextraction Combined with Liquid Chromatography‐Tandem Mass Spectrometry

A novel technique utilizing the adsorptive potential of immobilized multi‐walled carbon nanotubes (I‐MWCNT) in hollow fiber liquid‐phase microextraction (HF‐LPME) was developed for the determination of diuretics in urine. In this study, the potential of carbon nanotubes as a sorbent for three‐phase liquid‐phase microextraction of diuretics from urine samples was evaluated. Analysis was performed using liquid chromatography‐tandem mass spectrometry (LC‐MS/MS). A novel method was applied to detect acetazolamide (AAA), chlorothiazide (CTA), hydrochlorothiazide (HCT), hydroflumethiazide (HFT), clopamide (CA), trichlormethiazide (TCM), althiazide (AT) and bendroflumethiazide (BFT) in urine. Two‐step extractions using different times and temperatures for each step were adopted. Parameters influencing the extraction efficiency, including the extraction solvent, sample pH, salt concentration, extraction time and extraction temperature were systematically optimized. Under the resulting optimal extraction conditions, this method showed good linearity over an analytes concentration range of 1 to 1000 ng/mL, high extraction repeatability with relative standard deviations of less than 6%, and low detection limits (0.09 to 0.51 ng/mL). The application of the methods to the determination of diuretics in real samples was tested by analyzing urine samples of patient.     

Computational Study of the Substitution Effect on the Mechanism for the Gold(I)‐Catalyzed Ring Expansions of Unactivated Alkynylcyclopropanes

The ring expansion reactions of unactivated alkynylcyclopropanes X‐C≡C‐C₃H₅ → X‐C=C₄H₅ (X = H, F, Cl, Me, OMe, NMe₂, CMe₃) were examined using the density functional theory calculations. All of the structures were completely optimized at the B3LYP/6‐311++G** level of theory. For clarify the effect of the cationic gold(I), we also added AuPH₃⁺ as the catalyst into the system and the structures for Au were calculated at the B3LYP/LANL2DZ level of theory. The main finding of this work is that the singlet‐triplet splitting of X‐C≡C‐C₃H₅ play an important role in determining the kinetic and thermodynamic stability of the unactivated ring expansion reactions. When X‐C≡C‐C₃H₅ with a smaller singlet‐triplet splitting is utilized, the reaction has a smaller activation energy and a larger exothermicity.     

(Δ)[Fe(II)(phen)3]2+ Filled in the Chiral Cavitiy Constituted by {(Δ)[Fe(III)(C2O4)3](NH42+)(DMF)(H2O)32−}n

A chiral coordination compound {(Δ)[Fe(II)(phen)₃][(Δ)Fe(III)(C₂O₄)₃](NH₄)(H₂O)₃(DMF)}_n (phen = 1,10‐phenanthroline), (DMF = N,N'‐Dimethylformamide), has been synthesized, and the structure has been revealed by infrared spectroscopy and X‐ray single‐crystal diffraction. The framework consists of two chiral subunits. One subunit (Δ)[(Fe(III)(C₂O₄)₃]^3? which as host anion forms a chiral porous three‐dimensional supermolecular network with lattice water, lattice DMF and lattice ammonium cation through hydrogen bonds. And then the other is Δ[Fe(II)(phen)₃]²⁺ which as guest cation fills in the chiral cavity located in the previously mentioned host porous network.