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排序方式: 共有216条查询结果,搜索用时 15 毫秒
201.
202.
Falk Muench Sebastian Bohn Markus Rauber Tim Seidl Aldin Radetinac Ulrike Kunz Stefan Lauterbach Hans-Joachim Kleebe Christina Trautmann Wolfgang Ensinger 《Applied Physics A: Materials Science & Processing》2014,116(1):287-294
Electroless plating of metal films on polymer substrates usually requires the presence of metal particles acting as catalytically active nuclei for the deposition reaction. Herein, we present a novel and versatile approach towards the activation of polycarbonate substrates with metal nanoparticles. It is based on the diffusion of dimethylaminoborane into the polymer matrix, followed by reaction of the sensitized substrates with metal salt solutions. The reducing agent uptake was controlled by changing the duration of the sensitization and the dimethylaminoborane concentration in the sensitization solution. Different seed types (Ag, Au, Pd, Pt and Rh) were deposited by variation of the activation solution. The proposed mechanism was confirmed with FTIR and TEM measurements. In addition, AFM revealed that apart from a slight roughening in the nanometer range, the surface morphology of the polymer remained unchanged, rendering the method viable for template-based nanomaterial fabrication. Due to its pronounced variability, the new technique allows to tailor the activity of polymer substrates for consecutive electroless plating. The feasibility and nanoscale homogeneity of the process were proven by the electroless fabrication of well-defined Au and Pt nanotubes in ion-track etched polycarbonate templates. The combination of features (use of simple and easily scalable wet-chemical processes, facile seed variation, high activation quality on complex surfaces) renders the outlined technique promising for the fabrication of intricate nanomaterials as well as for the metallization of macroscopic work pieces. 相似文献
203.
Dr. Nicolas Panel Dr. Duc Duy Vo Nour Aldin Kahlous Dr. Harald Hübner Dr. Stephanie Tiedt Dr. Pierre Matricon Dr. Jody Pacalon Dr. Oliver Fleetwood Dr. Stefanie Kampen Andreas Luttens Dr. Lucie Delemotte Prof. Jan Kihlberg Prof. Peter Gmeiner Prof. Jens Carlsson 《Angewandte Chemie (International ed. in English)》2023,62(22):e202218959
G-protein-coupled receptors (GPCRs) play important roles in physiological processes and are modulated by drugs that either activate or block signaling. Rational design of the pharmacological efficacy profiles of GPCR ligands could enable the development of more efficient drugs, but is challenging even if high-resolution receptor structures are available. We performed molecular dynamics simulations of the β2 adrenergic receptor in active and inactive conformations to assess if binding free energy calculations can predict differences in ligand efficacy for closely related compounds. Previously identified ligands were successfully classified into groups with comparable efficacy profiles based on the calculated shift in ligand affinity upon activation. A series of ligands were then predicted and synthesized, leading to the discovery of partial agonists with nanomolar potencies and novel scaffolds. Our results demonstrate that free energy simulations enable design of ligand efficacy and the same approach can be applied to other GPCR drug targets. 相似文献
204.
The National Institute of Standards and Technology (NIST) Rocky Flats Soil-II Standard reference material (SRM) is being certified
through a statistical analysis of results from an interlaboratory comparison of fourteen laboratories from four countries.
Mean values were calculated as the most robust and reliable certified values for each of the radionuclides. Twenty two radionuclides
and four isotopes ratios were evaluated based on reported data. This article describes the approach for establishing the certified
values and uncertainties for the radionuclides in the Rocky Flats Soil II SRM. 相似文献
205.
206.
Alaa A. Hassan Ahmed M. Nour El-Din Fathy F. Abdel-Latif Sara M. Mostafa Stefan Bräse 《Chemical Papers》2012,66(4):295-303
The reaction of (substituted) alkenylidene-hydrazinecarbothioamides with 2-(1,3-dioxo-2,3-dihydro-1H-inden-2-ylidene)propanedinitrile led to the formation of 1,3-dioxospiroindene[1,3]-thiazine and thioxoindeno[2,1-d]imidazolone derivatives in modest yields. In addition, 1,3-dihydroxyindan-2-ylidenepropanedinitrile was found. Explanations
of these conversions involving nucleophilic reactions and condensations are presented. 相似文献
207.
This work offers construction and comparative evaluation the performance characteristics of conventional polymer (I), carbon paste (II) and carbon nanotubes chemically modified carbon paste ion selective electrodes (III) for meclofenoxate hydrochloride are described. These electrodes depend mainly on the incorporation of the ion pair of meclofenoxate hydrochloride with phosphomolybdic acid (PMA) or phosphotungestic acid (PTA). They showed near Nernestian responses over usable concentration range 1.0 × 10−5 to 1.0 × 10−2 M with slopes in the range 55.15–59.74 mV (concentration decade)−1. These developed electrodes were fully characterized in terms of their composition, response time, working concentration range, life span, usable pH and temperature range. The electrodes showed a very good selectivity for Meclo with respect to a large number of inorganic cations, sugars and in the presence of the degradation product of the drug (p-chloro phenoxy acetic acid). The standard additions method was applied to the determination of MecloCl in pure solution, pharmaceutical preparations and biological samples. Dissolution testing was also applied using the proposed sensors. 相似文献
208.
Hanan F. Abd El-Halim F. A. Nour El-Dien Gehad G. Mohamed Nehad A. Mohamed 《Journal of Thermal Analysis and Calorimetry》2012,109(2):883-892
Metal complexes having the general composition [MCl2(H2O)2(L)2]·yH2O (where y?=?1?C3, M?=?Mn(II), Cu(II), Co(II), Ni(II), and Zn(II) and L?=?miconazole drug?=?MCNZ) and [MCl2(H2O)2(L)2]Cl·3H2O (where M?=?Cr(III) and Fe(III)) have been synthesized. All the synthesized complexes were identified and confirmed by elemental analyses, IR, diffused reflectance, and thermal analyses (TG and DTA) techniques as well as molar conductivity and magnetic moment measurements. The molar conductance data reveals that bivalent metal complexes are non-electrolytes while Cr(III) and Fe(III) complexes are electrolytes and of 1:1 type. IR spectral studies reveal that MCNZ is coordinated to the metal ions in a neutral unidentate manner with N donor site of the imidazole-N. On the basis of magnetic and solid reflectance spectral studies, an octahedral geometry has been assigned for the complexes. Detailed studies of the thermal properties of the complexes were investigated by thermogravimetry (TG) and differential thermal analyses (DTA) techniques and the activation thermodynamic parameters are calculated using Coats?CRedfern method. The free MCNZ drug and its complexes were also evaluated against bacterial species (P. aeruginosa, S. aureus, B. subtilis, E. Coli) and fungi (A. fumigatus, P. italicum, and C. albicans) in vitro. The activity data show that the metal complexes have higher biological activity than the parent MCNZ drug. 相似文献
209.
Nahla Nour El Din Ahmed Salama Maissa Yacoub Salem Lobna Mohammed Abd El Halim Laila El‐Sayed Abdel Fattah 《中国化学》2012,30(1):183-189
Spectrofluorimetric and spectrophotometric stability‐indicating methods were developed and validated for analysis of veralipride (Ver) in presence of its hydrolytic and oxidative degradants. The spectrofluorimetric method was based on direct measurement of the intrinsic fluorescence of Ver at 366 nm after excitation at 299 nm using sodium lauryl sulfate (SLS) as micelle enhancer. The fluorescence intensity plot was linear over the concentration range 1.0–10.0 µg·mL?1. The high sensitivity of the method allowed its successful application to the analysis of Ver in spiked human plasma. Two other methods were developed. They are based on the oxidative coupling reaction of Ver with 3‐methyl benzothiazolin‐2‐one hydrazone (MBTH) hydrochloride in presence of ceric ammonium sulphate in an acidic medium. The first method depends on spectrophotometric measurement of the stable green colored oxidative coupling product at 660 nm. The different experimental parameters affecting the reaction were optimized. Linearity range is 10.0–100.0 µg·mL?1. The second method depends on a fluorescence quenching effect of Ver on the fluorescence of Ce3+. The difference in fluorescence intensity was measured at 380 nm after excitation at 300 nm. This method is applicable over the concentration ranges 0.25–2.50 µg·mL?1. The methods were validated according to the ICH guidelines. They were successfully applied for the analysis of Ver in drug substance, drug product and in laboratory prepared mixtures containing different percentages of hydrolytic and oxidative degradants. 相似文献
210.
Alaa A. Hassan Fathy F. Abdel-Latif Ahmed M. Nour El-Din Sara M. Mostafa Martin Nieger Stefan Bräse 《Tetrahedron》2012,68(40):8487-8492
Conjugated alkenylidene-hydrazinecarbothioamides react in high yield with 2,3-diphenylcyclopropenone to give a series of (E)-2,5-disubstituted 1,3,4-thiadiazolyl-2,3-diphenylpropenones. 相似文献