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81.
The infrared spectra (500–140 cm?1) of the complexes [M(pyridine)n(NCS)2] (n = 2, M = Mn, Co, Ni, Cu, or Zn; n = 4, M = Mn, Fe, Co, or Ni) are discussed. The v/M-pyridine and v/M-NCS bands are assigned by observing the band shifts induced by isotopic labelling of the coordinated pyridine and isothiocyanate, by comparing the spectra with those of the [M(pyridine)2Cl2] complexes and from symmetry considerations based on their known structures. The two types of metal-ligand stretching bands occur within a rather narrow frequency range and there is evidence of some vibrational coupling between these two modes. Some earlier assignments of vM-pyridine bands require revision. The spectra of the yellow [Fe(py)4(NCS)2] complex and its violet oxidation product suggest that the oxidation reaction involves the transformation of trans-[Fe(py)4(NCS)2] into cis-[Fe(py)3(NCS)3] 相似文献
82.
Tommy J. Mccord David R. Smith Janet K. Swan Anna M. Goebel Donald E. Thornton Criss C. Yakshe Alvie L. Davis 《Journal of heterocyclic chemistry》1979,16(6):1249-1252
Methyl 5-chloro- and 5,7-dichloro-2,1-benzisoxazole-3-carboxylates have been synthesized by treatment of o-nitromandelic and 5-chloro-2-nitroamandelic methyl esters, respectively, with thionyl chloride under appropriate reaction conditions. The structural assignments of both heterocyclic products were based on elemental and spectral analyses, and their conversion to the corresponding 5-chloro- and 5,7-dichloro substituted 2,1-benzisoxazole-3-carboxylic acids and isatins. Methyl α-chloro-o-nitrophenylacetate and o-nitrophenylcarbomethoxymethinyl sulfite were also obtained from reactions of methyl o-nitromandelate and thionyl chloride. A possible reaction mechanism involving two consecutive nucleophilic substitutions of methyl o-nitromandelate with thionyl chloride was proposed to account for the formation of methyl 5-chloro-2,1-benzisoxazole-3-carboxylate. 相似文献
83.
The IR spectra (3500—150 cm?1) of the complexes [M(aniline)2,X2 (M = Co, Ni, Cu, Zn; X = Cl, Br), [Zn(aniline)2I2] are discussed. Assignments of the internal ligand vibrations are based on the band shifts which result from 15N-labelling of the amino group. The metal—ligand stretching frequencies, ν(M—N) and ν(M—X), are assigned on the basis of the band shifts which occur on 15N-labelling and metal ion and halogen substitution. Two bands within the range 350–450 cm?1 are assigned to ν(M—N) while the ν(M—X) bands occur within the range 170–320 cm?1. The effects of structure and coordination number on ν(M—N) and ν(M—X) are discussed. The spectra of two ethanol adducts, [M(aniline)2-(ethanol)2Cl2] (M = Co, Ni) compared with those of the unsolvated species [M(aniline)2-Cl2], exhibit a unique band near 480 cm?1 which is insensitive to 15N-labelling and is assigned to ν(M—O). 相似文献
84.
85.
Ramn Macías Simon A. Barrett Jonathan Bould Udo Drfler Josef Holub John D. Kennedy Mark Thornton‐Pett Bohumil tíbr 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(5):520-522
Neutral 8‐(5‐iodo‐n‐pentyl)‐3‐(η5‐pentamethylcyclopentadienyl)‐arachno‐3‐rhoda‐7,8‐dithiaundecaborane, [Rh(C5H19B8IS2)(C10H15)], obtained from the [arachno‐7,8‐S2B9H10]? anion by treatment with I(CH2)5I followed by [Rh(C5Me5)Cl2]2 and N,N,N′,N′‐tetramethyl‐1,8‐diaminonaphthalene, has the 11‐vertex cluster geometry of [arachno‐7,8‐S2B9H10]?, but with an {Rh(C5Me5)} unit in the 3‐position instead of a {BH} unit, and with a –(CH2)5I chain attached exo to an S atom. 相似文献
86.
Bacterial infection activates the innate immune system as part of the host’s defense against invading pathogens. Host response to bacterial pathogens includes leukocyte activation, inflammatory mediator release, phagocytosis, and killing of bacteria. An appropriate host response requires resolution. The resolution phase involves attenuation of neutrophil migration, neutrophil apoptosis, macrophage recruitment, increased phagocytosis, efferocytosis of apoptotic neutrophils, and tissue repair. Specialized Pro-resolving Mediators (SPMs) are bioactive fatty acids that were shown to be highly effective in promoting resolution of infectious inflammation and survival in several models of infection. In this review, we provide insight into the role of SPMs in active host defense mechanisms for bacterial clearance including a new mechanism of action in which an SPM acts directly to reduce bacterial virulence. 相似文献
87.
Farago ME Kavanagh P Blanks R Kelly J Kazantzis G Thornton I Simpson PR Cook JM Parry S Hall GM 《Analytical and bioanalytical chemistry》1996,354(5-6):660-663
Concentrations of Pt, Pd, Rh and Au in soils and road dusts taken from areas of high and low traffic flows in the London Borough of Richmond and from a section of the Kingston bypass (A3) at New Malden, Surrey, have been measured. High concentrations of platinum are associated with high traffic densities. Samples taken from streets of lower traffic flows were found to contain the lower concentrations of the ranges. These values correlated well with the levels of lead which were also high at roundabouts. If the preliminary results obtained in this study apply more generally throughout the UK, then the potential for exposure to enhanced levels of Pt would appear to be higher for road users and for those living in urban environments or along major highways. 相似文献
88.
Bushra Y Ahmed Sridhara Chakravarthy Ruben Eggers Wim TJMC Hermens Jing Ying Zhang Simone P Niclou Christiaan Levelt Fred Sablitzky Patrick N Anderson AR Lieberman Joost Verhaagen 《BMC neuroscience》2004,5(1):1-11
Background
As development proceeds the human embryo attains an ever more complex three dimensional (3D) structure. Analyzing the gene expression patterns that underlie these changes and interpreting their significance depends on identifying the anatomical structures to which they map and following these patterns in developing 3D structures over time. The difficulty of this task greatly increases as more gene expression patterns are added, particularly in organs with complex 3D structures such as the brain. Optical Projection Tomography (OPT) is a new technology which has been developed for rapidly generating digital 3D models of intact specimens. We have assessed the resolution of unstained neuronal structures within a Carnegie Stage (CS)17 OPT model and tested its use as a framework onto which anatomical structures can be defined and gene expression data mapped.Results
Resolution of the OPT models was assessed by comparison of digital sections with physical sections stained, either with haematoxylin and eosin (H&E) or by immunocytochemistry for GAP43 or PAX6, to identify specific anatomical features. Despite the 3D models being of unstained tissue, peripheral nervous system structures from the trigeminal ganglion (~300 μm by ~150 μm) to the rootlets of cranial nerve XII (~20 μm in diameter) were clearly identifiable, as were structures in the developing neural tube such as the zona limitans intrathalamica (core is ~30 μm thick). Fourteen anatomical domains have been identified and visualised within the CS17 model. Two 3D gene expression domains, known to be defined by Pax6 expression in the mouse, were clearly visible when PAX6 data from 2D sections were mapped to the CS17 model. The feasibility of applying the OPT technology to all stages from CS12 to CS23, which encompasses the major period of organogenesis for the human developing central nervous system, was successfully demonstrated.Conclusion
In the CS17 model considerable detail is visible within the developing nervous system at a minimum resolution of ~20 μm and 3D anatomical and gene expression domains can be defined and visualised successfully. The OPT models and accompanying technologies for manipulating them provide a powerful approach to visualising and analysing gene expression and morphology during early human brain development. 相似文献89.
Ultrahigh light transmission through a C-shaped nanoaperture 总被引:1,自引:0,他引:1
Optical resolution beyond the diffraction limit can be achieved by use of a metallic nanoaperture in a near-field optical system. Conventional nanoapertures have very low power throughput. Using a numerical finite-difference time domain method, we discovered a unique C-shaped aperture that provides approximately 3 orders of magnitude more power throughput than a conventional square aperture with a similar near-field spot size of approximately 0.1 lambda. Microwave experiments at 6 GHz quantitatively confirmed the simulated transmission enhancement. The high transmission of the C-aperture--or one of the related shapes--is linked to both a propagation mode in the aperture and local surface plasmons. 相似文献
90.
The existence of a high-frequency, long-wavelength mode in a binary alloy is discussed on the basis of the fourth frequency moment of the correlation between concentration fluctuations. 相似文献