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91.
Starting from earlier work by Baudler we introduce a chemical heuristic for the systematic deduction and classification of covalent partial structures of phosphorus in polycyclic phosphanes, phosphorus-rich polycyclic phosphides, and allotropes of phosphorus except the black forms. This approach is used to direct ab initio techniques (which also confirm the rules) in the quest for as yet unknown forms of molecular or macromolecular phosphorus. Based on calculated stabilities of systematically generated structural alternatives we rationalize the stabilities of Hittorf's phosphorus and of molecular P4, confirm the possible existence of at least one other crystalline allotropic form of phosphorus, and provide insight into the probable structure of amorphous red phosphorus. In total, the combined approach of chemical heuristics and large scale ab initio calculations presented in this work supplies a coherent chemical understanding of covalent polyphosphorus structures. 相似文献
92.
93.
Bjrn kermark 《中国化学快报》2005,16(1):89-92
Two novel high valent complexes [M2(III, III)L(p--OAc)2].PF6 (M=Mn, Fe; 9) were prepared, where L was the tri-anion of 2,6-bis{[(2-hydroxy-3-(morpholin-4-yl methyl)-5-tertbutyl benzyl)(pyridyl-2-methyl)amino]methyl}-4-methyl phenol which contained additional phenolic, tert-butyl and morpholin-4-yl methyl groups compared to its parent [Mn2(Ⅱ, Ⅱ)(bpmp)(μ-OAc)2]-ClO4 (10). These improvements decreased the difference between the new model and (Mn)4 cluster (OEC in nature). 相似文献
94.
Rasa Pauliukaite Mariana Emilia Ghica Madalina Barsan Christopher M. A. Brett 《Journal of Solid State Electrochemistry》2007,11(7):899-908
The polymer redox mediator, poly(neutral red) (PNR), has been synthesised and characterised electrochemically to investigate
the best electropolymerisation and mediation conditions for application in enzyme biosensors and to clarify the mechanism
of action. Neutral red was electropolymerised by potential cycling on carbon film electrode substrates by allowing the monomer
to be oxidised during the full 20 cycles of polymerisation or reducing the positive limit of the potential window after the
first 2 cycles to impede monomer oxidation with a view to obtaining longer polymer chains and a lesser degree of branching.
Comparison was made with glassy carbon substrates. The PNR films on carbon film electrodes were characterised using cyclic
voltammetry and electrochemical impedance spectroscopy, as well as in glucose biosensors prepared with PNR. Glucose oxidase
enzyme was immobilised by encapsulation in silica sol-gel and compared with that obtained by cross-linking with glutaraldehyde.
The biosensors were evaluated by chronoamperometry in 0.1 M phosphate buffer saline solution, pH 7.0, and showed evidence
of electron transfer between the enzyme cofactor flavin adenine dinucleotide and PNR dissolved in the enzyme layer competing
with PNR-mediated electrochemical degradation of H2O2 formed during the enzymatic process.
This paper is dedicated to Professor Dr. Algirdas Vaskelis on the occasion of his 70th birthday. 相似文献
95.
基于支持向量机的羰基化合物红外光谱研究 总被引:1,自引:0,他引:1
设计了一个4层分等级分类系统,通过支持向量机技术对羰基化合物的红外光谱成功地进行了信息分类和提取,并与人工神经网络进行比较,结果表明:支持向量机对羰基类化合物红外光谱分类效果优于人工神经网络;另外详细探讨了表征酰胺类化合物的特征光谱峰片段对识圳伯仲叔酰胺的影响,证明了酰胺的N-H伸缩振动峰对识别伯仲叔酰胺贡献最大,为构建红外光谱智能解析系统提供了定量依据。 相似文献
96.
Yoshiaki?YuguchiEmail author Takahiro?Hirotsu Jun?Hosokawa 《Cellulose (London, England)》2005,12(5):469-477
Xyloglucan is a type of hemicellulose with a cellulose backbone containing (1→6)-α-xylose or (1→2)-β-galactoxylose as a side chain. It is soluble in water. Its aqueous solution forms a gel or gel-like precipitate by addition
of Congo red. Xyloglucan gel structures with various concentrations of Congo red were observed by small angle X-ray scattering
(SAXS) at the nano-level. SAXS results indicated that the xyloglucan chains interacted with Congo red, and that an increase
of concentration of Congo red induced a characteristic cross-linking domain, which consisted of a flat structure containing
stacked xyloglucan chain assemblies. The Congo red molecules are inserted between the xyloglucan chains. 相似文献
97.
本文对几种人工光合作用反应中心系统,做一个简单的综述,其中包括叶绿素和细菌叶绿素二聚体,卟啉二聚体,卟啉-苯醌共价键络合物以及其他合成中心。 相似文献
98.
Plant cells have been immobilized in alginate, where they have been shown to retain their biological activity. Such systems
can be utilized for bioconversions. 相似文献
99.
Brian A. Naughton Benson Sibanda Jory P. Weintraub Julia San Román Vafa Kamali 《Applied biochemistry and biotechnology》1995,54(1-3):65-91
A method of coculturing adult rat hepatic parenchymal cells (PC) and stromal cells in a three-dimensional framework of nylon
filtration screens or biodegradable polymer meshes was developed in our laboratory. Rat liver stroma, which includes vascular
and bile duct endothelial cells, fat-storing cells, fibroblasts, and Kupffer cells, were isolated by gradient centrifugation
afterin situ liver perfusion and expanded in monolayer culture prior to seeding onto nylon screens or bioresorbable polyglycolic acid
(PGA) polymers oriented into a felt-like construct. A second inoculum of freshly isolated PC was applied after the stromal
cells became established. Histological analyses revealed that PC proliferation occurred until all available space for expansion
within the template was exhausted. These cells retained their rounded morphology, and after 4–5 wk 7–9 “layers” of PC filled
the 140-μm deep template. Dioxin-inducible cytochrome P450 activity was detected for up to 58 d in culture, and albumin, fibrinogen,
transferrin, and soluble fibronectin were detected in the medium by enzyme-linked immunosorbent assay (ELISA) for 48 d in
vitro. Immunohistochemical analysis of sections through the cultures confirmed the presence of these proteins as well as cytokeratin
at the cellular level; the extracellular matrix stained for both collagen type III and laminin. Long-term PC proliferation
and function were enhanced by the presence of stromal cells as well as by a meshwork template whose geometry allows the interaction
of PC with stroma and matrix on several different planes. To permit transplantation, co-cultures of hepatic PC and stromal
cells were established on PGA felt constructs instead of nylon screens. After 24 d in vitro, these constructs were grafted
into sites in the mesentery, omentum, and sub-cutaneous tissues of adult Long-Evans rats. The growth of hepatocytes after
30 din situ was evident by histological analysis; grafts of co-cultures regenerated a liver-like architecture consisting of sinusoids
and putative biliary structures. In addition, PC at these extrahepatic graft sites were positive for albumin, transferrin,
and fibrinogen synthesis by immunohistochemistry. Graft survival was enhanced when recipients were subjected to 40% hepatectomy.
Hepatic PC:stromal cell cocultures may prove useful in the restoration of liver function either by direct transplantation
using PGA or similar templates, or as extracorporeal devices, using nylon screens. 相似文献
100.
S. Anandan S. Latha P. Maruthamuthu 《Journal of photochemistry and photobiology. A, Chemistry》2002,150(1-3):167-175
The synthesis, spectral and photoelectrochemical studies of mixed ligand complexes of [Ru(dcbpy)2(LL)]Cl2, where LL=2,4-(1,3-N,N′-dimethyl)pteridinedione (DMP), 6,7-dimethyl-2,4-(1,3-N,N′-dimethyl)pteridinedione (MDMP), 6,7-diphenyl-2,4-(1,3-N,N′-dimethyl)pteridinedione (PhDMP), dibenzo[h,j]-(1,3-N,N′-dimethyl)isoalloxazine (BIAlo), 6,7-bis(pyrid-2-yl)-2,4-(1,3-N,N′-dimethyl) pteridinedione (PyDMP) were carried out. These complexes were attached to sol–gel processed TiO2 electrodes and the photocells fabricated were illuminated with polychromatic radiation in the presence of I2/I3− as redox electrolyte. The incident photon to current conversion efficiency determined was found to be 20–48%. 相似文献