磁性纳米颗粒固定化细菌纤维素酶的活性和稳定性

在氨水溶液中进行Fe+2和Fe+3离子共沉淀并水热处理后制得磁性纳米颗粒Fe3O4,通过戊二醛活化将纤维素酶固定于其上。采用基于响应面法的Box-Behnken法(BBD)优化了制备条件,如磁性纳米颗粒浓度、戊二醛浓度、酶浓度和交联时间。 BBD分析结果表明,用实验数据可合理调节二次模型。利用生成的基于统计数据的等高线评价了响应面的变化,以理解纳米颗粒和酶活性之间的关系。运用扫描电镜、X射线衍射和红外光谱表征了纳米颗粒上酶的尺寸、结构、形貌和结合情况。采用诸如pH值、温度、重复使用性和存储能力分析了固定化纤维素酶的活性和稳定性。发现固定后的纤维素酶表现出更好的稳定性和活性。     

Potassium yttrium hexaniobium octadecachloride,KYNb6Cl18

The structure of potassium yttrium hexaniobium octadeca­chloride is built of anionic [Nb₆Cl₁₂ⁱCl₆^a]⁴⁻ cluster units (where `i' and `a' denote inner and outer ligands, respectively), linked together by K⁺ and Y³⁺ cations. The K⁺ cations occupy half of the tetrahedral vacancies in the face‐centered cubic lattice of cluster units, and are coordinated by 12 chloride ligands. The Y atom is located in an octahedral site and is bonded to six outer chloride ligands.     

An extensive review on thermodynamic aspect based solar desalination techniques

Journal of Thermal Analysis and Calorimetry - The shortage of freshwater is becoming a major threat to sustainable environmental development. Water desalination techniques provide solutions for...     

Color Tuning in New Metal‐Free Organic Sensitizers (Bodipys) for Dye‐Sensitized Solar Cells

Fun in the sun! A strategy has been devised for functionalizing and solubilizing boron dipyrromethene (Bodipy) dyes at the central boron atom and changing the color by increasing delocalization on the central core. This approach leads to the formation of stable B? C≡C and pyrrole? C?C linkages suitable for use in TiO₂‐sensitized devices (see figure).

     

Synthesis of novel 3-bromo-1,2-dihydroquinolines via palladium mediated intramolecular cyclization of N-tosyl-N-propargyl anilines

Facile synthesis of novel 3-bromo-1,2-dihydroquinolines by the intramolecular cyclization of N-tosyl-N-propargyl anilines catalyzed by Pd(OAc)₂ in conjunction with CuBr₂ and LiBr.     

Fabrication of printed memory device having zinc-oxide active nano-layer and investigation of resistive switching

An all printed resistive memory device, a 9-bit memristor, has been presented in this study consisting of 3 × 3 memristor crossbars deposited via electrohydrodynamic inkjet printing process at room conditions. Transparent zinc oxide active nano-layers, directly deposited by electrospray process, are sandwiched between the crossbars to complete the metal–insulator metal structure consisting of copper–zinc oxide–silver, where Cu and Ag are used as bottom and top electrodes respectively. The 9-bit memristor device has been characterized using current–voltage measurements to investigate the resistive switching phenomenon thereby confirming the memristive pinched hysteresis behavior signifying the read–write and memory characteristics. The memristor device showed a current bistability due to the existence of metal–oxide layer which gives rise to oxygen vacancies upon receiving the positive voltage hence breaking down into doped and un-doped regions and a charge transfer takes place. The maximum ON/OFF ratio of the current bi-stability for the fabricated memristor was as large as 1 × 10³, and the endurance of ON/OFF switchings was verified for 500 read–write cycles. The metal–insulator–metal structure has been characterized using X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscope techniques.     

Fractal analysis of viscoelastic data with automated gel point location and its potential application in the investigation of therapeutically modified blood coagulation

This study reports an automated numerical method for the location of the gel point in oscillatory shear data and demonstrates its potential application in measurements on therapeutically modified (heparinised) samples of healthy coagulating blood. Heparin prolongs the onset of clot formation and has a significant effect on the microstructure of the clot which is eventually formed. The results demonstrate the potential of this rheometrical technique as a new tool for monitoring the effect of heparin on samples of whole blood with significantly better linearity of response within the therapeutic range than another global coagulation monitoring technique (thromboelastography) which has previously been used.     

Ethylene Dehydroaromatization over Ga-ZSM-5 Catalysts: Nature and Role of Gallium Speciation

Bifunctional catalysis in zeolites possessing both Brønsted and Lewis acid sites offers unique opportunities to tailor shape selectivity and enhance catalyst performance. Here, we examine the impact of framework and extra-framework gallium species on enriched aromatics production in zeolite ZSM-5. We compare three distinct methods of preparing Ga-ZSM-5 and reveal direct (single step) synthesis leads to optimal catalysts compared to post-synthesis methods. Using a combination of state-of-the-art characterization, catalyst testing, and density functional theory calculations, we show that Ga Lewis acid sites strongly favor aromatization. Our findings also suggest Ga(framework)–Ga(extra-framework) pairings, which can only be achieved in materials prepared by direct synthesis, are the most energetically favorable sites for reaction pathways leading to aromatics. Calculated acid site exchange energies between extra-framework Ga at framework sites comprised of either Al or Ga reveal a site-specific preference for stabilizing Lewis acids, which is qualitatively consistent with experimental measurements. These findings indicate the possibility of tailoring Lewis acid siting by the placement of Ga heteroatoms at distinct tetrahedral sites in the zeolite framework, which can have a marked impact on catalyst performance relative to conventional H-ZSM-5.