磷烧伤的31P NMR研究

为了明确磷烧伤创面及吸收毒性物质的化学形式及分布.作者采用³¹P PNMR波谱,研究皮下注射黄磷、磷酸及磷烧伤后创面残留、肝脏及脑组织吸收的元素磷及其化合物含量.其结果皮下注射非致死与致死剂量的黄磷后,肝脏可测到元素磷的吸收,磷燃烧后创面磷绝大部分转化为磷酸及其结合物,极少部分以元素磷形式存在.致死面积的磷酸烫伤与磷烧伤后肝脏区域磷酸增加4~5倍,未检测到元素磷的波谱,各组脑组织均未检测到元素磷峰,而磷酸峰只有微小的增加.结论为磷烧烧后吸收的主要中毒物质与创面残留的主要化学物质一致,磷烧伤中毒的致死性主要是创面磷酸吸收所致.     

Use of flow microcalorimetry and dynamic mechanical thermal analysis for probing interphase structure in poly(styrene-b-butadiene-b-styrene)/magnesium hydroxide composites

Interactions between magnesium hydroxide (Mg(OH)₂ particles (both untreated and treated with 16-methyl heptadecanoic acid (isostearic acid)) and low molar mass poly(styrene) (PS) and poly(butadiene) (PB) have been studied by flow microcalorimetry (FMC) and have been related to the interphase structure in poly(styrene-b-butadiene-b-styrene) (SBS)/Mg(OH)₂ composites using dynamic mechanical thermal analysis (DMTA). The FMC studies revealed that both polymers adsorbed strongly onto an untreated magnesium hydroxide surface though the PB showed greater irreversible adsorption from the heptane carrier fluid. Diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) studies on filler samples removed from the FMC cell after the adsorption-desorption cycle confirmed strong polymer filler interaction. Adsorption of the low molar mass samples of PS and PB onto a pre-adsorbed monolayer of isostearic acid on Mg(OH)₂ resulted in a very significant reduction in polymer adsorption activity due to blockage of adsorption sites. DMTA studies revealed that strong adsorption of PS and PB blocks of SBS onto untreated filler in composites containing 60% w/w Mg(OH)₂ gave rise to phase mixing that led to an 18 °C reduction in the T _g of the PS phase relative to that in the unfilled matrix. However, in equivalent composites based on isostearic acid treated filler a smaller reduction (10 °C) was observed, therefore reflecting reduced filler-matrix interaction and reduced phase mixing.     

The study of the structure and bioactivity of the B2O3 • Na2O • P2O5 system

In this study, we have investigated calcium and silicate‐free samples over a wide compositional range in the xB₂O₃·30 Na₂O·(70−x)P₂O₅ system, with 0 ≤ x ≤ 70 mol%, in order to determine the influence of the chemical composition on their structure and bioactive response in simulated body fluid. Information related to the chemical structures present in the network was obtained by means of Raman and infrared spectroscopy. For samples containing small amounts of P₂O₅, boron structures are preponderant. Upon increasing the phosphorus content, the samples' network is based on phosphate chains linked by boron groups through ‘P–O–B’ bridges. For high concentration of P₂O₅, the Q³ units form three‐dimensional network, whereas Q² units assist the chain formation. Regarding the in vitro assessment of bioactivity, the clear print of PO₄ asymmetric bending vibrations of apatite‐like layer in the 540–680 cm⁻¹ spectral domain, the scanning electron micrographs and energy dispersive x‐ray analysis spectra demonstrate that the studied borophosphate samples exhibit good bioactive response only for certain chemical compositions. More exactly, the highest bioactivity is obtained for 30% and 20% B₂O₃ (mol%) after 3 and 11 days of immersion, respectively. Therefore, the samples with 20–30 mol% boron content are valuable candidates that can be used as materials for tissue engineering applications. Copyright © 2013 John Wiley & Sons, Ltd.     

Role of inorganic phosphate during electron transfer in the redox system NADH+flavin

We have used ³¹P NMR and EPR to study the effect of inorganic phosphate (P_i) on the process of electron transfer in oxidation of reduced nicotinamide adenine dinucleotide (NADH) by flavin in aqueous solutions. Observation of a significant (up to 40%) drop in the integrated intensity of the ³¹P NMR signal for the inorganic phosphate over the course of the reaction is interpreted as a manifestation of the effect of chemically induced polarization of the phosphorus nuclei during singlet-triplet conversion in charge-transfer complexes [NADH…P_i], and is evidence for a possible catalytic role for P_i in processes involving transfer of an electron (hydrogen atom) from NADH to appropriate acceptors. The results presented support the possibility of direct involvement of P_i in a chain of one-electron conversions in chemical systems. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 3, pp. 392–396, May–June, 2006.     

The Utilization of 18O Labelled Potassium Phosphate in Studies Concerning Fertilizer Phosphorus Assimilation by Plants

The utilization of ¹⁸O labelled potassium phosphate KH₂P¹⁸O₄, instead of radiophosphorus, ³²P, labelled phosphate in biochemical and ecological studies concerning fertilizer phosphorus assimilation by plants is presented.

The 30–60 mg dry plant samples were heated under 10^?2 mm Hg vacuum in Pyrex ampoules to form carbon dioxide (C¹⁶O¹⁸O) for ¹⁸O mass spectromietric analyses. Potassium phosphate labelled with 1.36 ¹⁸O atom per cent is sufficient to obtain a significant increase of the ¹⁸O plant content, the added ¹⁸O quantity in 0.5 kg soil being 1.4 × 10^?2 g ¹⁸O in this case.     

The 19F and 31P magnetic resonance spectra of phosphorus trifluoride in nematic solution

The phosphorus and fluorine N.M.R. spectra of PF₃ in a nematic solvent (EBBA) are discussed. The molecular geometry is found to agree with structures obtained from microwave and electron diffraction studies. The sign of the ordering parameter is assumed negative, the signs of the phosphorus fluorine coupling constant and of the chemical shift anisotropies follow from this assumption, and are found to be in agreement with theoretical predictions. The effect of temperature on the isotropic chemical shift of fluorine is discussed.     

Controlling surface states and photoluminescence of porous silicon by low-energy-ion irradiation

Porous silicon (PS) was irradiated by three kinds of low-energy ions with different chemical activity, namely argon ions, nitrogen ions and oxygen ions. The chemical activity of ions has significant effect on the surface states and photoluminescence (PL) properties of PS, The photoluminescence quenching after argon ions and nitrogen ions irradiation is ascribed to the broken Si-Si bonds, while the PL recovery is attributed to the oxidation of Si-H back bonds. Oxygen ions irradiation leads to the formation of a SiO_x layer with oxygen defects and PS shows different PL evolution than PS irradiated by argon ions and nitrogen ions.     

Intermacromolecular complexation due to specific interactions. 6. Miscibility and complexation between Poly{Styrene-co-[p-(2-Hydroxypropan-2-yl)Styrene]}and poly[n-butyl Methacrylate-co-(4-vinylpyridine)]

In recent years, considerable attention has been focused on polymer miscibility and Complexation due to hydrogen bonding. Monodisperse, proton-donating polystyrene (PS), that is, poly{styrene-co-[p-(2-hydroxypropan-2-yl)styrene]} [PS(t-OH)], was synthesized via chemical modification of polystyrene. Poly[n-butyl methacrylate-co-(4-vinylpyridine)] (BVPy), as a proton acceptor, was prepared by free-radical copolymerization of the corresponding monomers at low conversion. In organic solutions of PS(t-OH)/BVPy blends, viscometry was employed to study the Complexation behavior. Solvents with different proton-accepting abilities were used and hence proved to exert distinctive effects on solution complexation. In very dilute solutions, the complex aggregate was observed by static and dynamic light scattering (LS). Differential scanning calorimetry (DSC) investigation proved that miscibility could be greatly enhanced when a small amount of hydrogen bonding was introduced into the originally immiscible PS/PBMA (polybutyl methacrylate) system. Although it was found that the T _g of the hydrogen-bonding polymer complexes occurred at higher temperatures with respect to linear weight-average value, DSC measurement alone could not accurately distinguish polymer complexes from ordinary miscible blends. Based on the data of miscibility from DSC and complexation from vis-cometry in 1,2-dichloroethane for a few tens of blends, which cover broad ranges of the contents of interaction sites, a map showing the immiscibility-miscibility-complexation transitions by strengthening the hydrogen bonding for the system of PS(t-OH)/BVPy was successfully constructed.     

Crystal structure analysis of Li<Subscript>3</Subscript>PO<Subscript>4</Subscript> powder prepared by wet chemical reaction and solid-state reaction by using X-ray diffraction (XRD)

Lithium phosphate (Li₃PO₄) is one of the promising solid electrolyte materials for lithium-ion battery because of its high ionic conductivity. A crystalline form of Li₃PO₄ had been prepared by two different methods. The first method was wet chemical reaction between LiOH and H₃PO₄, and the second method was solid-state reaction between Li₂O and P₂O₅. Crystal structure of Li₃PO₄ white powder had been investigated by using an X-ray diffraction (XRD) analysis. The results show that Li₃PO₄ prepared by wet chemical reaction belongs to orthorhombic unit cell of β-Li₃PO₄ with space group Pmn2₁. Meanwhile, Li₃PO₄ powder prepared by solid-state reaction belongs to orthorhombic unit cell of γ-Li₃PO₄ with space group Pmnb and another unknown phase of Li₄P₂O₇. The impurity of Li₄P₂O₇ was due to phase transformation in solid state reaction during quenching of molten mixture from high temperature. Ionic conductivity of Li₃PO₄ prepared by solid-state reaction was ～3.10^?7 S/cm, which was higher than Li₃PO₄ prepared by wet chemical reaction ～4.10^?8 S/cm. This increasing ionic conductivity may due to mixed crystal structures that increased Li-ion mobility in Li₃PO₄.     

Electronic structure and chemical bonding of phosphorus-contained sulfides InPS4, TI3PS4, and Sn2P2S6

The electronic structure of phosphorus-contained sulfides InPS₄, Tl₃PS₄, and Sn₂P₂S₆ was investigated experimentally with X-ray spectroscopy and theoretically by quantum mechanical calculations. The partial densities of electron states calculated with the ab initio multiple scattering FEFF8 code correspond well to their experimental analogues—the X-ray K- and L_2,3-spectra of sulfur and phosphorus. The good agreement between theory and experiment was also achieved for K-absorption spectra of S and P in the investigated sulfides. In spite of the difference in the crystallographic structure of InPS₄, TI₃PS₄, and Sn₂P₂S₆ that influence the form of K-absorption spectra, the electronic structure of their valence bands are rather similar. This is due to the strong interaction of the P and S atoms, which are the nearest neighbors in the compounds studied. The electron densities of p- and s-states of phosphorus are shifted by about 3 eV to lower energies in comparison to the analogous electron states of sulfur. This is connected with the greater electro-negativity of sulfur, and is confirmed by the calculated electron charge transfer from P to S.     

Percolation approach to film formation from surfactant-free polystyrene particles

In this study, a film formation process from surfactant-free polystyrene (PS) latex particles is reported. Steady state fluorescence (SSF) and photon transmission (UVV) techniques were used to study the evolution of film formation. The latex films were prepared from pyrene (P)-labeled PS particles at room temperature and annealed at time intervals of 2.5?min above the glass transition temperature (T _g) of PS. During the annealing processes, the transparency of the film changed considerably. Fluorescence intensity (I _0P) from P was measured after each annealing step to monitor the stages of film formation. Evolution of transparency of latex films were monitored by using photon transmission intensity, I _tr. A drastic increase in I _tr and I _0P above the critical annealing times, t _r and t _c were attributed, respectively to percolation behavior of PS material from one side to the other side of the latex film. Critical exponents, β of percolation clusters were measured and found to be around 0.35 and 0.25 for I _tr and I _0P measurements, respectively.     

Dissolution and storage stability of nanostructured calcium carbonates and phosphates for nutrition

Rapid calcium (Ca) dissolution from nanostructured Ca phosphate and carbonate (CaCO₃) powders may allow them to be absorbed in much higher fraction in humans. Nanosized Ca phosphate and CaCO₃ made by flame-assisted spray pyrolysis were characterized by nitrogen adsorption, X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy. As-prepared nanopowders contained both CaCO₃ and CaO, but storing them under ambient conditions over 130 days resulted in a complete transformation into CaCO₃, with an increase in both crystal and particle sizes. The small particle size could be stabilized against such aging by cation (Mg, Zn, Sr) and anion (P) doping, with P and Mg being most effective. Calcium phosphate nanopowders made at Ca:P ≤ 1.5 were XRD amorphous and contained γ-Ca₂P₂O₇ with increasing hydroxyapatite content at higher Ca:P. Aging of powders with Ca:P = 1.0 and 1.5 for over 500 days gradually increased particle size (but less than for CaCO₃) without a change in phase composition or crystallinity. In 0.01 M H₃PO₄ calcium phosphate nanopowders dissolved ≈4 times more Ca than micronsized compounds and about twice more Ca than CaCO₃ nanopowders, confirming that nanosizing and/or amorphous structuring sharply increases Ca powder dissolution. Because higher Ca solubility in vitro generally leads to greater absorption in vivo, these novel FASP-made Ca nanostructured compounds may prove useful for nutrition applications, including supplementation and/or food fortification.     

Trace element analysis of hairs in patients with dementia

The trace elements of scalp hair samples from ≥60‐year‐old dementia patients and normal persons have been studied by X‐ray absorption near‐edge spectroscopy (XANES) in fluorescent mode and wavelength‐dispersive X‐ray fluorescence spectrometry. Comparisons of hair trace element levels of age‐matched dementia patients and normal persons revealed significantly elevated amounts of calcium, chlorine and phosphorus in dementia patients relative to normal persons. The results of XANES measurements identify the chemical forms of deposited calcium and phosphorus in the hair samples of both dementia patients and normal persons to be calcium chloride (CaCl₂) and phosphate (PO₄^3?), respectively. The amount of sulfur in hairs of dementia patients was found to be not significantly different from that in normal persons. The sulfur K‐edge XANES spectra, however, show significantly higher accumulations of sulfur in the sulfate (SO₄^2?) form in hairs of Alzheimer's disease and Parkinson's disease dementia patients. This study presents the possible roles of calcium, chlorine, phosphorus and sulfur in the etiology of dementia in elderly patients.     

Using Mössbauer spectroscopy to interpret histological analysis data of iron-containing compounds in rat brain

Ferrofluid containing magnetic nanoparticles of Fe₃O₄ was introduced into the rat brain ventricle via direct transcranial injection. Three months following the injection, the rats were euthanized and their brains investigated by means of histology and Mössbauer spectroscopy. It is demonstrated that the nanoparticles completely decomposed and were cleared from the brain, while the concomitant chemical compound accompanying the ferrofluid synthesis remained intact in the brain.     

Part III: Study of Tissue Distribution and Retention

The tissue distribution of colloidal zirconyl phosphate-P₃₂ and its retention following i.m and i.v. injection in mice were studied. About 63 per cent of the i.m. injected P₃₂ activity was retained at the site of injection after 5 days, suggesting the use of the colloid in the local treatment of tumours. The deposition of the colloid in bone and liver after i.v. injection presented zirconyl phosphateP₃₂ as useful in the radiotherapy of bone and liver disease.     

Ordered magnetic multilayer nanobowl array by nanosphere template method

Ordered magnetic multilayer [Co/Pt]_n nanobowls have been fabricated over a silicon substrate based on a polystyrene (PS) monolayer film. The ordered PS monolayer was first prepared by the self-assembly technique, which was used as the template for the multilayer film [Co/Pt]_n deposition. The ordered magnetic multilayer [Co/Pt]_n nanobowl array was obtained after the transferring and the selective etching process. The nanobowls show a uniform size and smooth surfaces. The nanobowls stuck to the neighbors and notches were observed in the bowl brims because of the contact points between the closed-packed PS beads. The nanobowls could be separated from their neighbors by thinning the PS beads before the film deposition and no notches were observed anymore. Compared to the chemical method, this method showed more flexible choices of the material to fabricate the nanobowls, which extended the application scope of the nanobowls greatly.     

Preparation of fluoride substituted apatite cements as the building blocks for tooth enamel restoration

Fluoride substituted apatite cement (fs-AC) was synthesized by using the cement powders of tetracalcium phosphate (TTCP) and sodium fluoride (NaF), and the cement powders were mixed with diluted phosphoric acid (H₃PO₄) as cement liquid to form fs-AC paste. The fs-AC paste could be directly filled into the carious cavities to repair damaged dental enamel. The results indicated that the fs-AC paste was changed into fluorapatite crystals with the atom molar ratio for calcium to phosphorus of 1.66 and the F ion amount of 3 wt% after self-hardening for 2 days. The solubility of fs-AC in Tris-HCl solution (pH 6) was slightly lower than hydroxyapatite cement (HAC) that was similar to the apatite in enamel, indicating the fs-AC was much insensitive to the weakly acidic solution than the apatite in enamel. The fs-AC was tightly combined with the enamel surface because of the chemical reaction between the fs-AC and the apatite in enamel after the caries cavities was filled with fs-AC. The extracts of fs-AC caused no cytotoxicity on L929 cells, which satisfied the relevant criterion on dental biomaterials, revealing good cytocompatibility. The fs-AC had potential prospect for the reconstitution of carious lesion of dental enamel.     

Control of spectral lines weakly absorbed by atmosphere in continuous wave chemical HF lasers

The behavior of two lines P _1-0(11) and P _2-1(8) weakly absorbed by the atmosphere is experimentally investigated in the spectra of cw chemical multikilowatt HF lasers of five types that differ in size and construction scheme of the nozzle array. It is shown that the intensity of these lines can be controlled within certain limits by varying the gas-dynamic regime of the laser operation, the chemical composition of the active medium, the orientation of the optical axis of the cavity and the cavity feedback factor, and the construction of the nozzle array.     

Behavioral,electrophysiological and histopathological consequences of systemic manganese administration in MEMRI

Manganese (Mn²⁺)-enhanced magnetic resonance imaging (MEMRI) offers the possibility to generate longitudinal maps of brain activity in unrestrained and behaving animals. However, Mn²⁺ is a metabolic toxin and a competitive inhibitor for Ca²⁺, and therefore, a yet unsolved question in MEMRI studies is whether the concentrations of metal ion used may alter brain physiology. In the present work we have investigated the behavioral, electrophysiological and histopathological consequences of MnCl₂ administration at concentrations and dosage protocols regularly used in MEMRI. Three groups of animals were sc injected with saline, 0.1 and 0.5 mmol/kg MnCl₂, respectively. In vivo electrophysiological recordings in the hippocampal formation revealed a mild but detectable decrease in both excitatory postsynaptic potentials (EPSP) and population spike (PS) amplitude under the highest MnCl₂ dose. The EPSP to PS ratio was preserved at control levels, indicating that neuronal excitability was not affected. Experiments of pair pulse facilitation demonstrated a dose dependent increase in the potentiation of the second pulse, suggesting presynaptic Ca²⁺ competition as the mechanism for the decreased neuronal response. Tetanization of the perforant path induced a long-term potentiation of synaptic transmission that was comparable in all groups, regardless of treatment. Accordingly, the choice accuracy tested on a hippocampal-dependent learning task was not affected. However, the response latency in the same task was largely increased in the group receiving 0.5 mmol/kg of MnCl₂. Immunohistological examination of the hippocampus at the end of the experiments revealed no sign of neuronal toxicity or glial reaction. Although we show that MEMRI at 0.1 mmol/Kg MnCl₂ may be safely applied to the study of cognitive networks, a detailed assessment of toxicity is strongly recommended for each particular study and Mn²⁺ administration protocol.