Investigation of thermal treatment of hybrid nanoparticles in a domain with different permeabilities

Journal of Thermal Analysis and Calorimetry - Porous domain filled with nanoliquid was scrutinized in the current article. Magnetic force and permeability were considered as main effective...     

Purification and Characterization of Thermostable α-Galactosidase from <Emphasis Type="Italic">Aspergillus terreus</Emphasis><Subscript>GR</Subscript>

An extracellular thermostable α-galactosidase producing Aspergillus terreus _GR strain was isolated from soil sample using guar gum as sole source of carbon. It was purified to apparent homogeneity by acetone precipitation, gel filtration followed by DEAE-Sephacel chromatographic step. The purified enzyme showed a single band after sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The molecular weight of the purified enzyme after SDS-PAGE was 108 kDa. The enzyme showed optimum pH and temperature of 5.0 and 65 °C, respectively, for artificial substrate pNPαGal. α-Galactosidase from A. terreus _GR is found to be thermostable, as it was not inactivated after heating at 65 °C for 40 min. The K _m for pNPαGal, oNPαGal, raffinose, and stachyose are 0.1, 0.28, 0.42, and 0.33 mM, respectively. Inhibitors such as 1,10-phenanthroline, phenylmethylsulfonyl fluoride, ethylenediaminetetraacetic acid, mercaptoethanol, and urea have no effect, whereas N-bromosuccinamide inhibited enzyme activity by 100%. Among metal ions tested, Mg²⁺, Ni²⁺, Ca²⁺, Co²⁺, and Mn²⁺ had no effect on enzyme activity, but Ag⁺, Hg²⁺, and Cu²⁺ have inhibited complete activity.     

The effects of different possible modes of uniaxial strain on the tunability of electronic and band structures in $$\text {MoS}_2$$ monolayer nanosheet via first-principles density functional theory

Although it is important for the study of graphene, identifying and characterizing the number of graphene layers is challenging. In this paper, we calculate graphene’s transmission. The result shows that the phase change is more sensitive than the intensity change when light passes through graphene in some THz frequencies. Based on this fact, a simple route is presented for identifying the single or few layers of graphene sheets by using terahertz phase contrast microscopy (TPCM). The route is fast, and easy to be carried out.     

A new chromogenic spray reagent for the detection and identification of oxyfluorfen herbicide in biological material by high-performance thin-layer chromatography

JPC – Journal of Planar Chromatography – Modern TLC -     

Stepwise elastic behavior in a model elastomer

Monte Carlo simulations of an entanglement-free cross-linked polymer network of semiflexible chains reveal a peculiar stepwise elastic response. For increasing stress, step jumps in strain are observed that do not correlate with changes in the number of aligned chains. We show that this unusual behavior stems from the ability of the system to form multiple ordered chain domains that exclude the cross-linking species. This novel elastomer shows a toughening behavior similar to that observed in biological structural materials, such as muscle proteins and abalone shell adhesive.     

First Example of a Modular Porphyrinoid Assembly Capable of Stabilizing Different Metal Ions in a Single Molecular Scaffold

We report the synthesis and characterization of porphyrin–corrole–porphyrin (Por‐Cor‐Por) hybrids directly linked at the meso–meso positions for the first time. The stability and solubility of the trimer are carefully balanced by adding electron‐withdrawing substituents to the corrole ring and sterically bulky groups on the porphyrins. The new hybrids are capable of stabilizing more than one metal ion in a single molecular scaffold. The versatility of the triad has been demonstrated by successfully stabilizing homo‐ (Ni) and heterotrinuclear (Ni‐Cu‐Ni) coordination motifs. The solid‐state structure of the NiPor‐CuCor‐PorNi hybrid was revealed by single‐crystal X‐ray diffraction studies. The Ni^II porphyrins are significantly ruffled and tilted by 83° from the plane of corrole. The robustness of the synthesized hybrids was reflected in the electrochemical investigations and the redox behaviour of the hybrids show that the oxidation processes are mostly corrole‐centred. In particular it is worth noting that the Por‐Cor‐Por hybrid can further be manipulated due to the presence of substituent‐free meso‐positions on both the terminals.     

Synthesis of Air‐ and Moisture‐Stable,Storable Chiral Oxorhenium Complexes and Their Application as Catalysts for the Enantioselective Imine Reduction

Air‐/moisture‐stable, crystalline, and storable chiral salicyloxazoline based oxorhenium(V) complexes have been synthesized and their catalytic application for the asymmetric reduction of ketimines using hydrosilane as hydride source is disclosed. A broad substrate scope, high yields, and excellent enantioselectivities (up to 99 %) are attained. Furthermore, the syntheses of enantiopure α‐amino esters, γ‐ and δ‐lactams, and isoindolinones have also been carried out using this methodology. Finally, the method has been applied to synthetic targets of pharmaceutical relevance, such as R‐(+)‐salsolidine and R‐(+)‐crispine A.     

Determination of some aldehydes by using solid-phase microextraction and high-performance liquid chromatography with UV detection

A new approach has been developed for the extraction and determination of aldehydes such as veratraldehyde, m-nitrobenzaldehyde, cinnamaldehyde, benzaldehyde, and p-chlorobenzaldehyde by using solid-phase microextraction (SPME) and high-performance liquid chromatography with UV detection (HPLC/UV). The method involves adsorption of the aldehydes on polydimethylsiloxane/divinylbenzene-coated fiber, followed by desorption in the desorption chamber of the SPME-HPLC interface, using acetonitrile-water (70 + 30) as the mobile phase; UV detection was at 254 nm. A good separation of 5 aldehydes was obtained on a C18 column. The detection limits of veratraldehyde, m-nitrobenzaldehyde, cinnamaldehyde, benzaldehyde, and p-chlorobenzaldehyde are 25, 41, 13, 12, and 11 pg/mL, respectively, which are about 100 times better than the detection limits for other SPME methods using gas chromatography. The proposed method was validated by determining benzaldehyde in bitter almonds and cinnamaldehyde in cinnamon bark. The recoveries of the 5 analytes were determined by analysis of spiked drinking water.     

A rapid and green method for expedient multicomponent synthesis of N-substituted decahydroacridine-1,8-diones as potential antimicrobial agents

Research on Chemical Intermediates - An efficient, green, high yielding, and quick method for the synthesis of N-substituted decahydroacridine-1,8-diones was achieved by multicomponent reaction...