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1.
2.
Two methods for the determination of polyethylene glycols (PEGs) in aqueous solution by precipitation with iodine have been developed. For PEGs with molecular weight 4 x 10(3)-2 x 10(4) the excess of iodine is titrated with thiosulphate, and for PEGs with average m.w. > 2 x 10(4) turbidimetric measurement is used. Both methods are relatively simple and give accurate and reproducible results. 相似文献
3.
The reaction of alkylpyridinium (CnH2n + 1NC5H5, hereafter Cn-Py) iodide salts in aqueous acetonitrile with a preformed palladium iodide precursor afforded two different types of organic-inorganic phases depending on the molar ratio. A 2:1 ratio yielded the phase [Cn-Py]2[PdI4] (3, n = 14, 16), which crystallized in the triclinic crystal system. The X-ray crystal structure of 3, (n = 14), refined in the space group P1 (a = 8.918(3) A, b = 9.894(3) A, c = 29.062(12) A, alpha = 93.51(3) degrees, beta = 94.17(3) degrees, gamma = 115.60(3) degrees, and Z = 2), consists of interdigitated bilayers with a basal spacing of 29.0 A. The aliphatic chains of the cations, which run almost parallel to the stacking direction, are fully stretched between polar planes built on isolated [PdI4]2- anions and cation headgroups. Changing the organic cation to palladium ratio to 1:1 led to a new phase [Cn-Py]2[Pd2I6] (4, n = 14, 16), which crystallizes in the triclinic P1 space group (a = 9.399(4) A, b = 14.264(6) A, c = 29.415(13) A, alpha = 92.11(4) degrees, beta = 90.07(4) degrees, gamma = 104.53(3) degrees, Z = 3 for 4(n = 14); a = 9.417(2) A, b = 14.215(3) A, c = 31.552(6) A, alpha = 87.96(3) degrees, beta = 87.63(3) degrees, gamma = 75.67(3) degrees, Z = 3 for 4(n = 16)). The layered structure is basically of a continuously interdigitated single-layer type, with a bilayer sublattice superimposed. Isolated [Pd2I6]2- anions contribute to the inorganic planes. A high degree of interdigitation and tilting of the aliphatic chains lead to basal spacings of 29.4 and 31.5 A for 4(n = 14) and 4(n = 16), respectively. The [Cn-Py]2[PdI4] and [Cn-Py]2[Pd2I6] phases were characterized by thermal analysis. Mesomorphic behavior was observed only for 3(n = 16), which was confirmed by variable-temperature powder XRD and optical microscopy. 相似文献
4.
Harshad S. Kapare Ranjitsinh Pawar Vrushali Neve Vrushali Bhalchim Prabhanjan S. Giram 《先进技术聚合物》2024,35(3):e6348
In recent years, advanced polymeric dendrimers have emerged as a promising avenue for AD management. Dendrimers are highly branched, three-dimensional macromolecules with precise nanoarchitectures, making them ideal candidates for the delivery of therapeutic agents and diagnostic tools. Their unique properties, such as well-defined size, multifunctionality, and controlled surface chemistry, allow for the design of targeted and highly efficient drug delivery systems and diagnostic probes. This review aims to provide a comprehensive overview of the potential applications of advanced polymeric dendrimers in the management of Alzheimer's disease. We explored their role in drug delivery, diagnostics, and other therapeutic interventions for AD. Additionally, we will delve into the challenges and opportunities in utilizing dendrimers as a key player in the battle against this devastating disease. The review will begin by discussing the current state of Alzheimer's disease, including its pathological features, clinical manifestations, and existing treatment strategies. It will then transition to an in-depth examination of polymeric dendrimers, highlighting their structural characteristics, synthesis methods, and biocompatibility. Subsequently, the review will delve into the various ways in which dendrimers can be tailored for AD management, including drug encapsulation and delivery, enhanced blood–brain barrier penetration, and targeted diagnostic imaging. Furthermore, we explored the potential benefits of dendrimer-based therapies, such as improved drug efficacy, reduced side effects, and enhanced patient compliance. The review will also address the challenges associated with dendrimer-based approaches, including toxicity concerns, regulatory hurdles, and the need for rigorous clinical evaluation. 相似文献
5.
Harish Holla Ian D. Jenkins Juliette E. Neve Rebecca H. Pouwer Ngoc Pham Simon J. Teague Ronald J. Quinn 《Tetrahedron letters》2012,53(52):7101-7103
A synthesis of the unusual cyclobutane-quinolinone alkaloids melicodenines C, D and E by intermolecular [2+2] cycloaddition is described. 相似文献
6.
The cytochrome P450 (P450) enzymes are mainly localized to the endoplasmic reticulum (ER), where they function within catalytic
complexes metabolizing xenobiotics and some endogenous substrates. However, certain members of families 1–3 were also found
in other subcellular compartments, such as mitochondria, plasma membrane, and lysosomes. The physiological function of these
enzymes in non-ER locations is not known, although plasma-membrane-associated P450s have been described to be catalytically
active and to participate in immune-mediated reactions with autoantibody formation that can trigger drug-induced hepatitis.
Several retention/retrieval mechanisms are active in the ER retention of the P450s and inverse integration of the translated
P450 into the ER membrane appears to be responsible for transport to the plasma membrane. Furthermore, hydrophilic motifs
in the NH2-terminal part have been suggested to be important for mitochondrial import. Phosphorylation of P450s has been described to
be important for increased rate of degradation as well as for targeting into mitochondria. It was also suggested that the
mitochondria-targeted P450s from families 1–3 could be active in drug metabolism using an alternative electron transport chain.
In this review we present an update of the field emphasizing studies concerning localization, posttranslational modification,
such as phosphorylation, and intracellular transport of microsomal P450s. 相似文献
7.
J.J. Neve C.F.J. de Meijer F.A.P. Blom 《Journal of Physics and Chemistry of Solids》1981,42(11):975-980
Shubnikov-de Haas oscillations in the transverse magnetoresistance of single-crystalline n-type CdSnAs2 have been recorded at temperatures between 2 and 25 K in magnetic fields up to 5T. The electron concentration of the samples ranged from 2 × 1017 to 2 × 1018 cm?3. The angular dependences of the oscillation periods and cyclotron effective masses showed that the conduction band exhibits an energy dependent anisotropy, obeying the Kildal band structure model. For the low-temperature values of the band parameters we found: a band gap Eg = 0.30 eV, a spin-orbit splitting Δ = 0.50 eV, a crystal field splitting parameter δ = ?0.09 eV, and an interband matrix element P = 8.5 × 10?8eV cm. This simple four-level model was found to be not adequate to describe quantitatively the observed electronic effective g-factor for a sample with low electron concentration. 相似文献
8.
C. C. Versace R. Bartolino M. Ghedini F. Neve S. Armentano M. Petrov N. Kirov 《Liquid crystals》1990,8(4):481-497
A comparative study of some mesogenic azobenzene compounds and their organometallic palladium(II) derivatives is reported. On the basis of the textural properties, calorimetric data and uniaxial order parameters (as deduced approximately from infrared spectroscopy), the main features induced by palladium complexation are (i) the transition temperatures increase, (ii) the number of ordered mesophases increases, (iii) the nematic uniaxial order parameter decreases, (iv) the textures are typical of highly ordered phases, and (v) an optical biaxiality appears in the nematic phase. The calorimetric data as well as the order parameters, if discussed in terms of molecular biaxiality result are interpreted at least qualitatively. Optical investigations show that macroscopical biaxial ordering can be achieved. 相似文献
9.
The thermotropic liquid crystalline behaviour of two N-alkylpyridinium tetrahalocuprates was investigated. The n-pentadecyl tetrachloro and tetrabromo derivatives (CU15-CL and CU15-BR, respectively) exhibit very similar behaviour on cooling, and specifically, a high temperature smectic phase followed by a cubic phase. We fully elucidated the Ia3¯d space group for the cubic phase from X-ray diffraction on single crystals. The type of cubic phase is still under discussion, but we suggest that it is a direct type of structure based on the known phase sequence of lower and higher homologues. A model for the local organization of CU15-CL and CU15-BR in the cubic and smectic mesophases is also proposed. 相似文献
10.
R. S. Neve 《International Journal of Heat and Fluid Flow》1993,14(4):341-348
A computational fluid dynamics technique has been used to predict the likely concentration levels along a pipe wall of chemicals injected radially from a nozzle. No published empirical data appear to be available, despite the importance of this subject in protecting pipe walls in the vicinity of the dosing point if the chemicals and pipe materials are incompatible. Validation of predictions is by comparison with experimental data for other parameters related to the flow. Where possible, results have been analyzed and presented in dimensionless form so that the article can act as a more generally useful design guide. 相似文献