SWELLING EQUILIBRIUM OF NONIONIC POLYACRYLAMIDE HYDROGEL IN AQUEOUS SALT SOLUTIONS

A series of nonionic polyacrylamide hydrogels, using acrylamide as monomer and N,N＇-methylene diacrylamide as crosslinking agent, were prepared by the free radical polymerization in aqueous solution. Swelling equilibria for the gels were carried out in aqueous solutions of NaCl, KCI, CaCl2, Na2HPO4 and K2HPO4 with concentration ranging from 10^-3 to 5mol/kgH2O at 25 ℃. Experimental results revealed that the chlorides and phosphates cause a different behavior at higher salt concentration. The swelling ratio increases with increasing concentration of chlorides salts, while decreases with the increased phosphates salt concentration. The phenomena seem to be related to the different interactions of chloride and hydrogen phosphate ions with the network groups. Furthermore, the effects of different concentration of crosslinking agent and total monomers on gel swelling performance were also investigated.     

带-带和带-平面电极的扩散极限电流

采用保角变换法推导了共平面的带-带电极和带-平面电极的稳态扩散极限电流及带-平面电极的稳态可逆极化曲线的分析表达式.     

反-1,2-二(苯并噁唑-1′3′-基-2′)乙烯及其衍生物的合成及光性能的研究

本文合成了反-1,2-二(苯并噁唑-1′3′-基-2′)乙烯及其衍生物共14种,确认了产品的结构,测试了它们的紫外吸收光谱、荧光发射光谱、激光转换效率,计算了它们的荧光量子产率,并观察了这类化合物在光照下发生的二聚反应。     

碳载CuTAPP的ESR研究(Ⅰ)

本文给出了碳载CuTAPP[Copper tetra-(p-trimethylammoniumphenyl)porphine iodide]的磁共振参数及由此得到的若干键参数和配体场跃迁能, 所得结果与文献中未碳载的铜卟啉和铜酞菁进行了比较。     

Hydrothermal synthesis of the first vanadomolybdenum polyoxocation with a "metal-bonded" spherical framework

The heteropoly compound [(V(V)O(4))Mo(VI)(12)O(36)(V(IV)O)(6)][(OH)(9)].11H(2)O (1), synthesized by hydrothermal method under weak basic conditions, represents the first mixed Mo/V six-capped Keggin structural derivative with a spherical skeleton, and the first transition metal polyoxocation. The successful synthesis of 1 demonstrates that basic hydrothermal synthesis might be a power synthetic route to the isolation of more new polycationic metal-oxo clusters.     

Robust,Superelastic Hard Carbon with In Situ Ultrafine Crystals

Advancement in developing superelastic carbon aerogels is highly demanded in new industry sectors, particularly in wearable functional electronics for artificial intelligence applications. However, it is very challenging to increase the compressive strength and electrical conductivity while lowering the density of carbon aerogels. Here, an ultralight and superelastic hard carbon aerogel with in situ ultrafine carbon crystals is reported. Based on a novel precursor prepared from self‐assembling bacterial cellulose and thiourea molecules, the resulting aerogel possesses a unique cellular structure and simultaneously exhibits remarkable compressive and electrical properties with ultralow density in addition to excellent compressive cyclability. Specifically, the normalized compression strength and electrical conductivity are up to 20 and 10 times, respectively, of reported carbon aerogels. Armed with the compressed aerogel electrodes, the supercapacitor exhibits excellent electrochemical performance in areal capacitance, rate capability, and high‐power cyclic stability. Furthermore, the supercapacitor displays distinguished pressure‐response capacitive signal and excellent signal cyclicality. This study provides a unique carbon aerogel for advanced wearable monitoring and energy storage systems.     

New chemistry of the triply bonded divanadium (V2 4+) unit and reduction to an unprecedented V2 3+ core

We report here the synthesis and characterization of seven new divanadium compounds with the paddlewheel geometry bridged by nitrogen-donating ligands. Five of these contain the diamagnetic V(2)(4+) core with short V-V distances of less than 2.0 A, consistent with a formal triple bond. The V-V distances vary with the basicity of the bridging ligands; more basic ligands such as those of the guanidinate type have the shorter metal-metal separations, and those with the less basic formamidinate groups have longer separations. One compound, V(2)(DPhF)(4) (DPhF = the anion of N,N'-diphenylformamidine), has been reduced by one electron, and two structures, [K(THF)(3)]V(2)(DPhF)(4) and [K(18-crown-6)(THF)(2)]V(2)(DPhF)(4), have been obtained. These have an unprecedented V(2)(3+) core where the formal oxidation state of each vanadium atom is +1.5. The decrease in V-V bond distance and the multiline EPR spectrum in the reduced species provide evidence that these two molecules contain a bond of order 3.5.     

How to make a major shift in a redox potential: ligand control of the oxidation state of dimolybdenum units

A compound reported earlier (Polyhedron 1989, 8, 2339) as (Bu(n)()(4)N)(2)H(2)[Mo(2)[Mo(CO)(4)(PhPO(2))(2)](2)] has been reexamined. We find that the hydrogen atoms in this formula are not present. Therefore, the complex must be considered as having a central triply bonded Mo(2)(6+) unit, instead of a quadruply bonded Mo(2)(4+) unit. Our conclusion is based on a variety of experimental evidence, including X-ray crystal structures of four crystal forms, as well as the neutron crystal structure of one. This explains the relatively long Mo-Mo bond lengths found in the range 2.1874(7)-2.2225(7) A and the absence of a delta --> delta transition in the visible spectrum. From electrochemistry we also find that the diphosphonate ligand has such an exceptional ability to stabilize higher oxidation states that even common solvents such as CH(2)Cl(2) and C(2)H(5)OH readily oxidize the Mo(2)(4+) unit that is introduced from the Mo(2)(O(2)CCH(3))(4) or [Mo(2)(O(2)CCH(3))(2)(NCCH(3))(6)](BF(4))(2) employed in the preparation. The only chemically reversible wave at E(1/2) = -1.54 V vs Ag/AgCl corresponds to the reduction process Mo(2)(6+) --> Mo(2)(5+).     

固相配位化学反应研究——ⅩⅩⅩⅩⅠ.[Co(NH3)5(H2O)]Br3,[Cr(NH3)5(H2O)](NO3)3与无机盐KY(Y=Cl,Br,Ⅰ)的固相反应动力学研究

本文主要用气相色谱逸出气体分析方法,借助于红外、紫外可见漫反射谱等手段研究了[Co(NH₃)₅(H₂O)]Br₃、[Cr(NH₃)₅(H₂O)](NO₃)₃与无机盐KY(Y=Cl,Br,Ⅰ)的固相反应,计算了失水与失氨的动力学参数,发现第一步反应失水生成一取代中间产物,其活化能与外加阴离子无关,为S_N     

Water-soluble cyclodextrin polymers for enhanced relative recovery of hydrophobic analytes during microdialysis sampling

Microdialysis relative recovery (RR) enhancement using different water-soluble, epichlorohydrin-based cyclodextrin polymers (CD-EPS) was studied in vitro for different analytes, amitryptiline, carbamazepine, hydroquinone, ibuprofen, and 4-nitrophenol. When compared to the native CDs (alpha, beta, and gamma) on a per mole basis, the CD-EPS enhanced microdialysis RR was either statistically greater or the same. beta-CD-EPS was more highly retained than native beta-CD by a 20 000 Da molecular weight cutoff (MWCO) polycarbonate membrane, but showed no statistical difference for loss across a 100 000 Da MWCO polyethersulfone membrane (PES). When the same weight percent of beta-CD or beta-CD-EPS was included in the microdialysis perfusion fluid, the beta-CD-EPS produced a higher microdialysis RR than native beta-CD for all analytes across the PES membrane. However, enhancements for the PC membrane were statistically insignificant when beta-CD and beta-CD-EPS were compared on a per mole basis. These results suggest that CD-EPS may be used as effective enhancement agents during microdialysis sampling and for some membranes provide the additional advantage of being retained more than native CDs.