Selection of peptomeric inhibitors of bovine α-chymotrypsin and cathepsin G based on trypsin inhibitor SFTI-1 using a combinatorial chemistry approach

A peptomeric library consisting of 360 monocyclic analogues of trypsin inhibitor SFTI-1 isolated from sunflower seeds was designed and synthesized by a solid-phase approach in order to select chymotrypsin and cathepsin G inhibitors. All peptomers contained a proteinogenic-Phe-mimicking N-benzylglycine (Nphe) at positions 5 and 12. Into the synthesized library, different peptoid monomers were introduced in the 7–10 segment. Deconvolution of the library against both proteinases through an iterative method in solution revealed that the strongest chymotrypsin inhibitory activity was displayed by two analogues, [Nphe^5,12]SFTI-1 (1) and [Nphe^5,12, Naem⁸]SFTI-1 (2), where Naem stands for N-(2-morpholinoethyl)glycine. After deconvolution against a cathepsin G analogue, [Nphe^5,12, Npip^8,9, Nnle¹⁰] SFTI-1 (3) (Npip = N-(3,4-methylenedioxybenzyl)glycine) appeared to be the most potent inhibitor with a high serum stability. It is worth noting that the analogues obtained by a combinatorial approach display high specificity towards one of the experimental enzymes. Another interesting feature is the lack of Pro8 in analogues 2 and 3, the amino acid residue absolutely conserved in the family of Bownan–Birk inhibitors.     

Synthesis of submicron CaZrO<Subscript>3</Subscript> in combustion reactions

Submicron CaZrO₃ powder is obtained in combustion reactions (solution combustion synthesis—SCS) with glycine. It is found that SCS reduces the sintering temperature of CaZrO₃ powders. The dielectric properties of calcium zirconate ceramics are studied by the electrochemical impedance method. It is shown that a ceramics of powders obtained by the SCS method has high dielectric characteristics.     

Synthesis, characterization and applications of nanostructural/nanodimensional metal oxides

Molybdenum oxide nanorods (MOx-NR) and vanadium oxide nanotubes (VOx-NT) have been prepared using MoO₃ and V₂O₅ powders as precursors and hexadecylamine as surfactant via hydrothermal route. Porous nanocrystalline MgO powder has been prepared by a simple and instantaneous solution combustion process using corresponding magnesium nitrate as oxidizer and glycine as fuel. The compounds are characterized by XRD, TG-DTA, SEM, TEM, surface area and porosity measurements. Because of the porous nature having large surface area (107 m²/g) with nanodimension (12-23 nm), MgO powder has been successfully employed as defluoridizing agent for the removal of fluoride (75%) in ground water     

Lattice damage and Al-metal precipitation in 2.5 MeV-electron-irradiated AlH3

AlH₃ powder was bombarded with energetic electrons at 20 K and at room temperature and investigated by EPR, NMR, X-ray diffractometry, and microwave dielectric-constant measurements. The EPR spectra of the irradiated powder and of a selected single crystal cuboid of mm edge show a complex asymmetric line centered at g = 2.009, with a Curie-like temperature dependence, attributed to radiation-induced color centers and/or their agglomerates. At the same time, the grains, which have become shiny black after irradiation, exhibit an increase of both the real and the imaginary part of . ²⁷Al-NMR spectra of the irradiated powder present a Knight-shifted line at 1600(50) ppm, close to the position of bulk metallic Al, and corresponding to a concentration of c(Al) . In addition, the main hydride line differs from that before irradiation, demonstrating an alteration of environmental symmetry. The irradiation induces also a change in shape and width of the ¹H-NMR line, another indication of symmetry change in the lattice. Finally, a refined X-ray single-crystal structure analysis of the irradiated cuboid indicates a change of structure from trigonal R -3 c to R -3, with a loss of mirror symmetry for the two Al sites caused by the introduction of Al-defects in the vicinity of one of them. Received: 20 October 1997 / Revised: 24 December 1997 / Accepted: 30 January 1998     

In situ monitoring of the solution‐mediated polymorphic transformation of glycine: characterization of the polymorphs and observation of the transformation rate using Raman spectroscopy and microscopy

The aim of this work was to investigate the mechanism and progression of the solution‐mediated polymorphic transformation and crystallization of glycine. The identification of the α‐ and γ‐forms of glycine crystals was performed using powder X‐ray diffraction (PXRD), Raman microscopy and in situ probe Raman spectroscopy. The influence of the addition of NaCl and of the process parameters such as saturation temperature, seed size and stirring speed on the transformation behavior from the metastable α‐ form to the stable γ‐ form was examined. In situ probe Raman spectroscopy was used to monitor the solid‐phase properties—polymorphic composition. Fourier transform infrared spectroscopy (FTIR) with a ZnSe window was used to track the liquid‐phase concentration at different times. Besides, the polymorphic transformation of glycine in the solvent was also examined in situ using a microscope with a heating/cooling stage. The integration of the different offline and in situ analytical measurement techniques greatly assisted in accurately and quantitatively perceiving the fundamental phenomena that govern the transformation process. Copyright © 2008 John Wiley & Sons, Ltd.     

Orientational disorder and geometrical isomeric effect on nonlinear optical properties of poly bis(glycine)cadmium chloride

Poly bis(glycine)cadmium chloride (BGCC) crystals of both undoped and doped with thiourea (Tu) were grown from saturated solutions by a slow evaporation technique. The geometrical isomerism of the octahedral BGCC molecule is investigated using single crystal XRD, powder XRD and FT-IR. The significant difference between the two isomers namely facial (fac) and meridional (mer), is explained in terms of the different point group symmetries of C₃ and C₁, respectively. The loss of point group symmetry from C₃ to C₁ is attributed for the observed powder second-harmonic generation (SHG). Semi-empirical calculations from the optimized geometrical parameters also supported non-linear optical properties of the material.     

Triangular antiferromagnetic order in the honeycomb layer lattice of

ErCl₃ crystallizes in the AlCl₃-type layer structure. The crystal structure was refined in the paramagnetic state by powder neutron diffraction. The monoclinic lattice parameters at 1.5 K are a = 6.8040(3)?, b = 11.7456(5)?, c = 6.3187(3)? and . The space group is C2/m. Short-range, predominantly in-plane, magnetic ordering occurs above 350 mK up to several Kelvin. Below mK a three-dimensional antiferromagnetic order with a propagation vector of sets in. The magnetic structure of ErCl₃ was determined by powder and single-crystal neutron diffraction at temperatures down to 45 mK. The Er³⁺ ions are located on two-dimensional honeycomb layers in the a–b plane. There are two antiferromagnetically coupled triangular sublattices which form right- and left-handed helices along the c-axis. The magnetic moments are oriented in the a–b plane and amount to 3.3(1) at saturation. From the temperature dependence of the integrated neutron magnetic peak intensity a critical exponent (2) was derived for the magnetic phase transition. Received 1 December 1999 and Received in final form 21 July 2000     

Growth and design of novel nonlinear optical material (NLO) ⿿ Glycine barium nitrate potassium nitrate (GBNPN) crystal

A potentially useful semi organic nonlinear optical (NLO) material ? glycine with barium nitrate and potassium nitrate (GBNPN) has been synthesized by slow evaporation technique. Good transparent GBNPN crystals were obtained in a time span of 3 weeks. The grown crystals were characterized by single crystal/powder XRD, UV?vis?IR absorption, FTIR, thermal analysis and powder SHG measurements have been studied. The grown crystals were thermally stable up to 137.53 °C. The GBNPN crystal exhibits second harmonic generation efficiency of about 1.35 times than that of potassium di hydrogen phosphate (KDP). Mechanical properties such as micro hardness (H_v) and Mayer's index, n, have been carried out by indentation method. The refractive index (μ) has been measured by the Brewster's angle method.     

Effect of oxygen on the electrophysical properties of some carbon allotropes (graphite and C60 fullerene)

The electrophysical properties of powder samples of graphite and C₆₀ fullerene have been studied in vacuum, oxygen ambient, and air. Room-temperature conduction of the samples has a percolative character. An increase of temperature brings about an increase of sample conductivity caused by oxygen desorption from the bulk. A peak-shaped feature not observed before has been found in the temperature behavior of the resistance of finely dispersed C₆₀ and graphite powder samples in the T=310–340 K interval. Oxygen atoms were found to be involved in charge transport in powder samples of graphite and C₆₀ fullerene through their electrical activity on the surface of grains differing in size. Fiz. Tverd. Tela (St. Petersburg) 39, 1703–1705 (September 1997)     

Dynamic compaction of copper powder: 2D numerical simulation and experimental results

Abstract

A method for plate-impact dynamic compaction of copper powder has been developped. The optimization of the experimental set-up (impedance adjustments, tensile wave traps, relative thickness of impactor and target,…) is presented.

2D axisymetrical numerical simulations have been performed with a Lagrangian finite element code. Geometrical characteristics of the experimental set-up as well as the dynamic response of the powder (Reaugh equation of state) and of the material of the set-up have been taken into account. These simulations show that, due to the difference in shock velocities in the container and in the powder, the powder is submitted to 2D loading waves. As a matter of fact the powder may be loaded by a non-planar shock wave propagating in the as-expected direction, as well as by a sweeping wave initiated at the bottom of the powder container, and propagating obliquely from the bottom-up. This second wave loads the bottom of the powder first. The influence of the impactor thickness as well as its material on the shock front shape and on the shock density-pressure history of the material has been studied. 1D simulations are shown not to evaluate properly the stress history and the energy deposition in the powder sample.

Metallographic observations as well as X-ray tomography experiments have been performed on consolidated samples. A very good agreement has been found between results of 2D numerical simulations and the observed final shape and density maps of the samples. The shape of deformed powder particles are also in agreement with the expected shock history.     

Magnetic behavior and physicochemical properties of Ni and NiO nano-particles

A series of nano-crystalline Ni/NiO particles was synthesized by a combustion route depending upon the glycine-nitrate process. The as prepared samples were characterized by X-ray diffraction (XRD), scanning electron micrograph (SEM), transmission electron micrograph (TEM), nitrogen adsorption isothems at 77 K and vibrating sample magnetometer (VSM) techniques.The XRD results revealed that the Ni powder crystallizes was formed with the cubic phase when the molar ratio of glycine to nitrate is 1.5. Above or below that molar ratio, NiO phase coexists as an impurity along with the Ni phase. The SEM and TEM measurements of the as synthesized powders showed that the particles are irregular in shapes and have porous morphology. Increasing the ratio between glycine and Ni-nitrate resulted in slightly agglomeration and grain growth of nano-particles with subsequent decrease in the value of surface area depending upon high combustion heat. The magnetization value of Ni measured at room temperature is very close to the value observed for commercial Ni powder.     

Phonon echo in L-alanine

Phonon echo signals have been observed in a finely-dispersed crystalline powder of the L-alanine amino acid. Measurements of the relaxation time T ₂ have revealed a phase transition in L-alanine crystals at a temperature of about 170 K. Fiz. Tverd. Tela (St. Petersburg) 40, 2119–2120 (November 1998)     

Measurements of compressibility of solids and powder compacts by a strain gauge technique at hydrostatic pressure up to 9GPa

Abstract

An experimental technique is described which enables one to measure the pressure-volume (P-V) relationship of solids and powder compacts and the linear compressibility of anisotropic single crystals by means of the resistive strain gauges at hydrostatic pressure up to 9 GPa. The potential of this technique is demostrated for solids possessing pressure induced phase transitions (PbTe, SmSe) and anisotropic crystals (Sb). For the first time P-V relationship is measured for highly compressible powder compact at increase and decrease of pressure.     

A pressure induced phase transition in pyroxene

Abstract

Two monoclinic pyroxenes of composition Ca(Fe,Mg)Si₂O₆ were studied up to 10 GPa using X-ray powder diffraction and ⁵⁷Fe Mössbauerspectroscopy. The results are indicative of a phase transition at 4 GPa.     

Synthesis of oxide ceramic powder by reaction in supercritical fluids

Abstract

The reaction of the alkoxide Mg(Al(OR)₄)₂ in supercritical fluid ethanol around 350°C and 15 MPa leads to the formation of partly crystallized submicronic powder. The dried solid particle size measured by TEM ranges from about 0.04 to 0.2 μm. The spinel MgAl₂O₄ is formed after heating the dried powder at 1200°C. Structural properties determined by X-ray diffraction and IR spectroscopy as well as thermal behaviour of these powders are compared with those of samples elaborated from sol-gel process.     

Crystal structure refinement at high pressures using angle-dispersive powder diffraction techniques

Abstract

The development of area detectors such as the imaging plate (IP) allows the use of angle-dispersive techniques for powder diffraction studies at high pressure. Integration of the 2-d pattern greatly improves the powder averaging and signal-to-noise ratio, making it possible to carry out full Rietveld refinements of crystal structures in high-pressure phases. An IP system is being developed at the Synchrotron Radiation Source (SRS), Daresbury, and the current status of this system -hardware and software -is described. Recent results on La₂CuO₄ and lnSb demonstrate the effectiveness and advantages of the techniques.     

Synthesis,crystal growth and characterization of a semiorganic material: Calcium dibromide bis(glycine) tetrahydrate

Single crystals of semiorganic material calcium dibromide bis(glycine) tetrahydrate were grown from aqueous solution. The crystal belongs to monoclinic system, with a = 13.261(5) Å, b = 6.792(2) Å, c = 15.671(9) Å and β = 91.68(4)°. The presence of the elements in the title compound was confirmed by energy dispersive X-ray analysis. The solubility and metastable zone width were found. The grown crystals were tested by powder XRD, FTIR, Thermo Gravimetric and Differential Thermal Analysis, UV–vis–NIR analysis, dielectrical and mechanical studies. The transmittance of calcium dibromide bis(glycine) tetrahydrate crystal has been used to calculate the refractive index n, the extinction coefficient K and both the real ɛ_r and imaginary ɛ_i components of the dielectric constant as functions of wavelength. The optical band gap of calcium dibromide bis(glycine) tetrahydrate is 3.23 eV.     

The synthesis of intermetallic compounds under dinamic compression of powder mixture on metal surface

Abstract

The initial powder mixtures (Fe-Si, Nb-Al, Al-Ni) were shock loaded on the surface of steel plates. The structure investigation of obtained surface layers reveals homogeneous distribution of elements and formation of intermettallides.     

Pressure-Effect on Anatase Titanium Dioxide

Pressure-induced phase transition of anatase titanium dioxide was investigated by Raman, absorption spectroscopy and X-ray diffraction. The change in Raman and absorption spectra with pressure revealed that the transition from anatase to high pressure phase with f -PbO 2 structure (TiO 2 -II) occurred in the pressure range of 4.0-4.6 GPa for a single crystal. The X-ray powder diffraction patterns indicate the presence of superstructural lattice of anatase at pressures more than 3 GPa. The superstructure of anatase disappears on the release of the pressure. A sluggish transition to the high pressure phase is also observed. The anatase coexists with the high pressure phase at 5.2 GPa. The difference in the results between optical spectroscopy (single crystal) and X-ray diffraction (powder) will be due to crystalinity of the sample.     

DNA binding and cleavage studies of new sulfasalazine-derived dipeptide Zn(II) complex: Validation for specific recognition with 5′–TMP

Synthesis, characterization, DNA binding and cleavage studies of [Zn(glygly)(ssz)(H₂O)]·6H₂O (1) containing glycyl glycine and sulfasalazine ligand. Complex 1 recognize minor groove of DNA and show hydrolytic DNA cleavage.

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Highlights? Novel Zn(II) complex 1 bearing bioactive glycyl glycine and sulfasalazine ligand scaffold. ? Cleavage activity of 1 was enhanced in presence of activators: H₂O₂>MPA>GSH>Asc. ? Complex 1 recognize minor groove as depicted in the cleavage pattern and molecular docking. ? Complex 1 cleaves pBR322 DNA via hydrolytic mechanism and validated by T4 DNA ligase experiments.