共查询到20条相似文献,搜索用时 31 毫秒
1.
Confocal laser scanning microscopy (CLSM) was applied to detect the intracellular [Ca2 ] variety of fluorescent intension, with Fluo-3/AM fluorescence loaded in SFSMC. The results show that 10 μmol/L Lacidipine can reduce the frequence which 10 μmol/L 5-HT induced [Ca2 ] spark in SFSMC of calcium over loading to 50%, and amplitude to 50% or so. We can draw a conclusion that dihydropyridines cal-cium antagonists lacidipine can antagonize the release of intracellular [Ca2 ] which 5-HT-induced in dose dependent manner. 相似文献
2.
Simulation of calcium oxalate stone in vitro 总被引:3,自引:0,他引:3
Urolithiasis constitutes a serious health problem that affects a significant section of mankind. Between 3% and 14% of the population, depending on the geographical region, suffer from this illness[1]. For example, the incidence of urolithiasis in Florida in the United States of America was 15.7 in 100000 people and increased to 20.8 in 1996. Urolithiasis remains a major medical prob-lem in China, especially in Guangdong Province. A survey in 1997 in Shenzhen City, the most southern city i… 相似文献
3.
Hui Du Jianyu He Sicen Wang Langchong He 《Analytical and bioanalytical chemistry》2010,397(5):1947-1953
The dissociation equilibrium constant (K
D) is an important affinity parameter for studying drug–receptor interactions. A vascular smooth muscle (VSM) cell membrane
chromatography (CMC) method was developed for determination of the K
D values for calcium antagonist–L-type calcium channel (L-CC) interactions. VSM cells, by means of primary culture with rat
thoracic aortas, were used for preparation of the cell membrane stationary phase in the VSM/CMC model. All measurements were
performed with spectrophotometric detection (237 nm) at 37 °C. The K
D values obtained using frontal analysis were 3.36 × 10−6 M for nifedipine, 1.34 × 10−6 M for nimodipine, 6.83 × 10−7 M for nitrendipine, 1.23 × 10−7 M for nicardipine, 1.09 × 10−7 M for amlodipine, and 8.51 × 10−8 M for verapamil. This affinity rank order obtained from the VSM/CMC method had a strong positive correlation with that obtained
from radioligand binding assay. The location of the binding region was examined by displacement experiments using nitrendipine
as a mobile-phase additive. It was found that verapamil occupied a class of binding sites on L-CCs different from those occupied
by nitrendipine. In addition, nicardipine, amlodipine, and nitrendipine had direct competition at a single common binding
site. The studies showed that CMC can be applied to the investigation of drug–receptor interactions. 相似文献
4.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1983,39(12):1077-1082
In order to obtain information about the structure of Ca10-x Pbx(PO4)6(OH)2 (O<x<10) compounds, powder X-ray diffraction patterns and i.r. absorption spectra have been studied. Solid solutions of the complete series have been obtained and lattice parameters dimensions and cation distribution in unequivalent sites are given. OH, PO4, CO3 and cation oxygen fundamental frequencies were assigned. 相似文献
5.
Jia Ming Liu Tian Long Yang Xiao Mei Huang Xiu Mei Shi Zhong Bin Shi Hong Wu Guo Hui Zhu Zhi Ming Li Cui Lian Chen Department of Chemistry Environmental Science Zhangzhou Normal College Zhangzhou China Department of Food Biological Engineering Zhangzhou Institute of Technology Zhangzhou China 《中国化学快报》2007,18(2):195-197
A new method for the determination of trace calcium by solid substrate-room temperature phosphorimetry is established. It is based on the fact that chromeazurols azurol S-phenanthroline-NaCMC (CAS-phen-NaCMC) system can emit strong and stable room temperature phosphorescence (RTF) on the solid substrate in the filter paper. Ca2 and phenanthroline can form complex ion Ca(phen)32 , which will form complex [Ca(phen)3(CAS)2] with CAS. In the result, the number of CAS molecules in each spot increased, causing sharp increase of the RTP signal of the CAS-phen-NaCMC system. 相似文献
6.
7.
K. Wieczorek-Ciurowa P. Dulian A. Nosal J. Domagała 《Journal of Thermal Analysis and Calorimetry》2010,101(2):471-477
The effect of alkaline hydrothermal activation of class-C fly ash belite cement was studied using thermal analysis (TG/DTG)
by determining the increase in the combined water during a period of hydration of 180 days. The results were compared with
those obtained for a belite cement hydrothermally activated in water. The two belite cements were fabricated via the hydrothermal-calcination
route of class-C fly ash in 1 M NaOH solution (FABC-2-N) or demineralised water (FABC-2-W). From the results, the effect of
the alkaline hydrothermal activation of belite cement (FABC-2-N) was clearly differentiated, mainly at early ages of hydration,
for which the increase in the combined water was markedly higher than that of the belite cement that was hydrothermally activated
in water. Important direct quantitative correlations were obtained among physicochemical parameters, such as the combined
water, the BET surface area, the volume of nano-pores, and macro structural engineering properties such as the compressive
mechanical strength. 相似文献
8.
Summary A liquid chromatographic method incorporating column-switching and fluorimetric detection for the determination of triamterene in untreated urine, is described. The urine samples (5 L) were directly introduced onto an Hypersil ODS-C18, 30 m (20 mm×2.1 mm I.D.) pre-column. Polar urinary compounds were removed by flushing the pre-column with water for 1 min, and the analyte was then switched onto an HP-LiChrospher RP C18,5 m (125 mm×4mm ID) analytical column using an acetonitrile/phosphate buffer gradient elution. Fluorescence detection was performed at 230 nm excitation and 430 nm emission wavelengths. The recovery of drug was 102±2% in the 0.10–20.0 g/mL concentration range, the limit of detection being 5 ng/mL. A validation of the usefulness of this procedure was accomplished by analysing urine extracts obtained from real samples.Hypersil ODS is not a product of Merck, Germany. Please give supplier (p. 5). 相似文献
9.
Yi Ming Liu Sui Ping Deng Hui Zheng Jian Ming Ouyang 《中国化学快报》2007,18(3):345-348
The ring patterns of calcium oxalate crystals were induced by domains in Langmuir-Blodgett (LB) films of dipalmitoylpho- sphatidylcboline (DPPC). The result was explained by the defects at the ring boundaries of liquid condensed (LC) and liquid expanded (LE) phases of LB film. These boundaries could provide less free energy and much more nucleating sites for COM crystals. 相似文献
10.
《Solid State Sciences》2000,2(1):31-38
Calcium is chosen as a test case for the validity of the ‘flat band/steep band’ scenario in superconductivity. Its electronic structure is reexamined by means of the self-consistent all-electron full potential LMTO and LMTO-ASA method based on the local-density approximation (LDA). The lattice properties and the electron-phonon interactions are calculated from first principles based on the linear-response theory in the LMTO frame. Our results are in reasonable agreement with experiment. Some new observations on the electronic structure close to the Fermi level are made based on the comparison between the theoretical and experimental results. Calcium does not become and according to our results should not become superconducting. 相似文献
11.
Alaaeldine Sh. Saleh Jong-Il Yun 《Journal of Radioanalytical and Nuclear Chemistry》2017,313(1):93-99
Solvent extraction studies on the purification of uranium from zirconium rich sodium diuranate (SDU) feed was carried out using n-tri butyl phosphate (TBP) as extractant and n-decanol as phase modifier. The presence of Zr in SDU leached solution leads to the formation of third phase during liquid–liquid extraction of uranium which was successfully prevented by addition of n-decanol in 30% (v/v) TBP/n-dodecane mixture. A seven stage counter current extraction of SDU feed solution followed by five stage stripping were carried out using optimum concentration of phase modifier 15% n-decanol-30% TBP in n-dodecane as solvent. Based on the findings a process flow-sheet has been developed for the purification of SDU to nuclear grade ammonium diuranate. 相似文献
12.
Alberto Albis José Manuel Lozano Javier Sancho Carmen M. Romero 《Journal of Thermal Analysis and Calorimetry》2011,104(1):37-44
Thermal stability of bovine α-lactalbumin in the presence of three different calcium concentrations in aqueous solutions of
several concentrations of erythritol, xylitol, sorbitol, and inositol at pH 6.5 was evaluated by UV absorbance, fluorescence
spectroscopy, and circular dichroism spectroscopy. At the selected conditions, the thermal denaturation process is reversible
and is well described by a two-state model. Results show a higher stability for the holo form of the protein in the presence
of calcium, followed by the holo- and the apo-lactalbumin, respectively. The stabilizing effect of the polyols increases with
polyol concentration and it is higher for the apo-lactalbumin than holo-lactalbumin and is very small for the protein in the
presence of a calcium excess. 相似文献
13.
Ill Yong Kim Chikara Ohtsuki Giichiro Kawachi Masanobu Kamitakahara Sung-Baek Cho 《Journal of Sol-Gel Science and Technology》2008,45(1):43-49
Bioactive ceramics show specific biological activity, a bone-bonding ability, and are used as bone-repairing materials. Particles
of bioactive ceramics may be used as fillers for fabricating bioactive composites where bioactive fillers are dispersed in
a polymer matrix. Chemical bonding between the filler and the organic matrix requires an effective organic modification of
the bioactive filler. Previous studies have reported that inorganic glasses in the CaO–SiO2 system act as fundamental components showing bioactivity, as they show a high potential to form bone-like apatite after exposure
to a body fluid. Therefore, organically modified microspheres composed of CaO–SiO2 gels can be useful as bioactive fillers to produce bioactive composites. In this study, the conditions for the preparation
of organically modified gels composed of CaO–SiO2 were investigated using sol–gel processing of tetraethoxysilane, calcium nitrate tetrahydrate and silane coupling agents
(SCAs), such as 3-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, and 3-glycidoxypropyltrimethoxysilane (GPS),
along with polyethyleneglycol (PEG). Spherical particles with diameter of 2–3 μm were obtained when adding the SCAs, except
for GPS with PEG. Incorporation of the SCAs was confirmed using Fourier transform infrared spectroscopy. All the samples prepared
with the SCAs formed bone-like apatite on their surfaces in a simulated body fluid within a period of 1 day. These results
indicate that bioactive microspheres of organically modified CaO–SiO2 gels can be obtained using sol–gel processing with SCAs. 相似文献
14.
Senapati S 《The Journal of chemical physics》2007,126(20):204710
The author has performed three independent molecular dynamics computer simulations to examine the effects of counterion identity on hydrogen-bond dynamics in the enclosed water pool of anionic surfactant-based reverse micelles. The water-water hydrogen-bond lifetime in the reverse micelle (RM) with calcium ions is found to be longer than that in the RM with sodium or ammonium ions. The hydrogen bond between a polar head group and a water molecule, on the other hand, breaks but reforms most rapidly in the RM with calcium ions, indicating that there exists a strong competition between head group-counterion and head group-water interactions at such complex interfaces. 相似文献
15.
Using high intensity ultrasonic irradiation, we prepared calcium phosphate–albumin colloidal particles from aqueous solutions of Ca(H2PO4)2 and Ca(OH)2 in the presence of bovine serum albumin (BSA). The effect of concentration of BSA (2–5 g/L) properties of the colloidal particles was studied at constant temperature. The effect of a resting period on the size distribution of the colloidal particles was also investigated. Morphology, phase composition, average diameter, size distribution and zeta potential were obtained by transmission electron microscopy, X-ray diffraction, particle size determination by PCS and electrokinetic measurements. 相似文献
16.
José A. F. Gamelas Ana F. Lourenco Paulo J. Ferreira 《Journal of Sol-Gel Science and Technology》2011,59(1):25-31
This study focus on the modification of the particles of precipitated calcium carbonate (PCC) with silica formed in situ by
sol–gel method. The new materials were characterized by several spectroscopic, analytical and microscopic techniques. A dense
film of highly branched silica was formed at the surface of the scalenohedral PCC crystals. The amount of silica deposited
at the PCC surface, as determined by thermogravimetric analysis, reached up to 25 wt% under appropriate experimental conditions.
Particle size distributions obtained by laser diffraction spectroscopy of the new modified PCC’s were close to the distribution
of the original PCC, even considering that some variation in the average size of the particles was noted. This result is of
great interest regarding the application of these materials, for instance, as fillers in the paper industry since the coating
of silica may contribute to the fibre-to-fibre bonding, thus improving paper strength. 相似文献
17.
Pereira RF Valente AJ Fernandes M Burrows HD 《Physical chemistry chemical physics : PCCP》2012,14(20):7517-7527
The interaction of sodium octanoate, decanoate or dodecanoate with calcium(ii) in aqueous solutions has been studied using turbidity, conductivity and potentiometric measurements. These show a marked alkyl chain length dependence on the behaviour. At the calcium concentration used (1.0 mM), there is little interaction with the octanoate, the decanoate shows initially formation of a 1:1 complex, followed by precipitation, while the dodecanoate precipitates at low surfactant concentrations. The solid calcium carboxylates were prepared, and show lamellar, bilayer structures with planes of calcium(II) ions coordinated to carboxylate groups through bidentate chelate linkages. Thermogravimetry and elemental analyses indicate the presence of coordinated water with the calcium decanoate but not with longer chain carboxylates. The results of both the solution and solid state studies suggest that precipitation of long-chain carboxylates depends on a balance between hydration effects and hydrophobic (largely van der Waals') interactions. Electrostatic effects make little energetic contribution but play the important structural role of ordering the carboxylate anions before precipitation. Differences are observed in the interactions between calcium(II) and long chain alkylcarboxylates and alkylsulfates, and are interpreted in terms of stronger binding to the metal of the carboxylate group. A general mechanism is proposed for calcium carboxylate precipitation from aqueous solution based on this and previous studies. 相似文献
18.
《Journal of Coordination Chemistry》2012,65(22):3651-3658
A new polyoxometalate based on saturated Wells-Dawson polyanions and calcium cations, H2[Ca2(P2W18O62)(H2O)5]?·?7.5H2O (1), has been synthesized in aqueous solution and characterized by single-crystal X-ray diffraction and IR. Compound 1 is a new example of 3D framework based on Wells-Dawson anions that act as chelate ligands to coordinate with calcium cations. Cyclic voltammetry reveals that the pH of the supporting electrolytic solution has a marked effect on the electrochemical behavior. 相似文献
19.
Résumé Les auteurs ont élaboré une méthode semi-micro et micro-gravimétrique et une méthode spectrophotométrique pour le dosage du calcium par la lorétine. Après avoir établi le facteur analytique du lorétinate de calcium par voie gravimétrique et thermogravimétrique, ils ont démontré la possibilité de doser le calcium à l'échelle semi-micro gravimétrique pour des quantités allant de 5 mg à 50 mg, l'erreur moyenne étant de 0,35%. La méthode microgravimétrique permet de ramener la quantité minima à doser à 0,2 mg de calcium par ml, l'erreur moyenne étant de 0,45%. L'influence d'une série d'ions étrangers fut étudiée. La plupart ne gênent pas le dosage, même s'ils sont présents en quantités importantes. Par spectrophotométrie indirecte, notamment en redissolvant le lorétinate de calcium dans un excès d'une solution ferrique, les auteurs ont réussi à doser des quantités de calcium de l'ordre de 20g avec une erreur moyenne de 0,35%.
Summary The authors have elaborated a method (semi-micro and micro-gravimetric) and also a spectrophotometric method for determining calcium by means of loretin. After establishing the analytical factor for calcium loretinate by the gravimetric and the thermogravimetric methods, they showed the possibility of determining calcium on the semimicro gravimetric scale for quantities ranging from 5 mg to 50 mg, the mean error being 0.35%. The microgravimetric method allows the minimum quantity to be determined to be reduced to 0.2 mg calcium per ml, the mean error being 0.45%. A study was made of the influence of a number of foreign ions. Most of them do not harm the determination, even though they are present in considerable amounts. By indirect spectrophotometry, notably by dissolving the calcium loretinate in an excess of ferric solution, the writers have succeeded in determining amounts of calcium of the order of 20g with a mean error of 0.35%.
Zusammenfassung Die Verfasser haben eine semimikro- und eine mikrogravimetrische Methode und ein spektrophotometrisches Verfahren zur Bestimmung von Calcium mit Loretin (7-Jod-8-hydroxychinolin-5-sulfonsäure) ausgearbeitet. Nach Festlegung des Umrechnungsfaktors des Calciumloretinats auf gravimetrischem und thermogravimetrischem Wege wurde gezeigt, daß durch Semimikrogravimetrie Calciummengen von 5 bis 50 mg mit einem mittleren Fehler von 0,35% bestimmbar sind. Die mikrogravimetrische Methode eignet sieh für 0,2 mg Calcium/ml mit einem mittleren Fehler von 0,45%. Der Einfluß einer Reihe von Fremdionen wurde untersucht. Die meisten davon stören nicht, auch wenn sie in bedeutender Menge vorhanden sind. Durch indirekte Spektrophotometrie, nämlich durch Auflösen des Calciumloretinats in überschüssiger Eisen(III)lösung gelang es, Calciummengen in der Größenordnung von 20g mit einem mittleren Fehler von 0,35% zu bestimmen.相似文献
20.
Sunho Oh Myung-Ho Han Wan-Bin Im Suk Young Kim Kyo Han Kim Changkook You Joo L. Ong 《Journal of Sol-Gel Science and Technology》2010,53(3):627-633
Coatings of biomedical implant surfaces by a bioactive calcium phosphate film render bioactivity to the implant surface and
shorten the healing time. In this present study, calcium metaphosphate (CMP) sol was synthesized by sol–gel method and coated
onto the titanium alloys (Ti-6Al-4V). CMP sol was first synthesized by reacting Ca(NO3)24H2O (Sigma–Aldrich 99%, USA) with (OC2H5)3P (Fluka 97%, Japan) in methyl alcohol. A stoichiometric Ca/P ratio of 0.5 was obtained by varying the amounts of the reactants.
Sol was then coated on Ti-6Al-4V substrates by spin coating. The coated-specimens were then dried at 70 °C for 24 h, followed
by a heat treatment at 650 °C for 1 h. Structural and chemical properties of the coatings were evaluated using XRD, SEM, and
EPMA. The dissolution property of the coated-CMP layer was investigated by immersing the samples in the simulated body fluid
(SBF) for 1, 3, 7 and 21 days. The concentration of Ca2+ released was measured using ICP. After heat treatment, SEM indicated a smooth and uniform CMP layer, with CMP grains of approximately
100 nm. The CMP phase was identified with δ-CMP (JCPDS #9-363). After immersion in SBF, coatings were observed to be roughened
and porous. The concentration of Ca2+ in SBF was observed to increase over time, indicating continuous dissolution. The presence of titanium oxide phosphate compounds
were also observed on CMP surfaces after immersion. It was thus concluded that the ability to control coating properties as
well as the need for low heat treatment temperature offers advance for the use of CMP coating by sol–gel process on Ti-6Al-4V
implant surfaces. 相似文献