A blue luminescent binuclear cadmium-orotate coordination polymer: synthesis,crystal structure,and thermogravimetric analysis

Assembly of orotic acid (H₃Or, 1,2,3,6-tetrahydro-2,6-dioxo-4-pyrimidinecarboxylic) and Cd(NO₃)·6H₂O yielded a coordination polymer, [(Cd(Hor)·2.5H₂O)₂]_n (1), which has been characterized by X-ray single-crystal diffraction, TGA, and ?uorescence spectra. Single-crystal X-ray structural analyses reveal that 1 is a hydrogen-bonded binuclear Cd-orotate coordination polymer in which both Cd²⁺ ions have different coordination environments with identical distorted octahedral geometry. Crystal data for 1: monoclinic, space group P2₁/n, a = 7.0209(10) Å, b = 13.974(2) Å, c = 17.541(3) Å, β = 98.842(2)°, V = 1700.5(4) Å, Z = 4, R1 = 0.0269, wR2 = 0.0612, θ_max = 25.960. The emission spectrum of the Cd-complex recorded with 265 nm excitation wavelength reveals the complex has strong blue luminescence with the peak maximum 420 nm (2.95 eV) as a result of the n–π* and π–π* transitions on the H₃Or ligand.     

MIR imaging bundles of ordered silver halide polycrystalline fibres for thermal transmission and imaging

This study aims to experimentally examine the energy-saving potential by using R-134a filled separated two-phase thermosiphon loop (STPTL) for data center applications. A parametric study had been made to compare the energy consumption of two data center racks. Two fin-and-tube heat exchangers were attached to one of the racks to form two individual thermosiphon loops. The experiments were carried out subject to different operating conditions, including three ambient temperatures (20 °C, 23 °C, and 27 °C) and filling ratios ranging from 30 to 90% in association with heating loads ranging between 1.5 kW and 6 kW. Parametric influences regarding concentrated heat loading or uniform heat loading are studied. It was found that an appreciable energy-savings can be obtained at high filling ratios and a maximum of 49% energy-saving with the assistance of thermosiphon is observed. Accordingly, the rising of system pressure will result in noticeable savings. Relative to the uniform heat loading of the data rack, the thermosiphon shows even more energy-saving potential in concentrated heat loading. This phenomenon is more pronounced at a lower ambient temperature like 20 °C. On the other hand, there is no appreciable energy-saving for the thermosiphon between concentrated and uniform heating loads when the ambient temperature is high (27 °C). Furthermore, the influence of airflow rate was also investigated under various ambient temperatures with a 90% filling ratio and a heating load of 6 kW. The results revealed that the lower airflow rate in the thermosiphon yields comparatively better energy-saving than the higher flow rate. The study on the influence of using two STPTLs indicated that 15–23% energy-saving can be achieved at a 90% filling ratio and 6 kW heating load for all the studied ambient conditions if compared with testing each loop separately. Lower thermal resistance is seen at the higher filling ratios, ambient temperatures, and heating loads.

     

Syntheses, structural and antimicrobial studies of a new N-allylamide of monensin A and its complexes with monovalent metal cations

A new N-allylamide of monensin A (M-AM2) was synthesized and its capacity to form complexes with Li⁺, Na⁺ and K⁺ cations was studied by ESI MS, ¹H and ¹³C NMR, FTIR spectroscopy and PM5 semi-empirical methods. ESI mass spectrometry indicates that M-AM2 forms complexes with Li⁺, Na⁺ and K⁺ of exclusively 1:1 stoichiometry which are stable up to cv=70 V, and the formation of 1:1 complexes between M-AM2 and Na⁺ cations is strongly favoured. Above cv=90 V we observe fragmentation of the respective complexes involving several dehydration steps. The spectroscopic studies show that the structures of the M-AM2 and its complexes with Li⁺, Na⁺ and K⁺ cations are stabilized by intramolecular hydrogen bonds in which the OH groups are always involved. The data also demonstrate that the CO amide group is engaged in the complexation process of each cation. However with the K⁺ cation we also found a structure in which this CO amide group does not participate in the complexation to a significant extent. The in vitro biological tests of M-AM2 amide show its good activity towards some strains of Gram-positive bacteria (Giz 13-19 mm; MIC 25-100 μg/ml).     

Simultaneous Production of Lipids and Carotenoids by the Red Yeast Rhodotorula from Waste Glycerol Fraction and Potato Wastewater

Applied Biochemistry and Biotechnology - Abstract The objective of this study was to determine the possibility of simultaneous biosynthesis of lipids and carotenoids by the Rhodotorula yeast...     

Membranes with a plasma deposited titanium isopropoxide layer

Porous polypropylene membranes were coated with plasma polymerized titanium isopropoxide in a 75 kHz plasma reactor. It was noted that the presence of air in the plasma chamber increased the amount of deposited polymer. Selection of the process parameters enabled obtaining membranes with up to 300 εg cm^?2 of polymerized titanium isopropoxide. Deposition of the titanium oxide layer resulted in the reduction of permeate flux but it significantly improved the membrane photocleaning ability. The recovery index reached the level of 95 % for membranes with the highest amount of the titanium oxide deposit.     

Thermal properties,phase transitions,vibrational and reorientational dynamics of [Mn(NH<Subscript>3</Subscript>)<Subscript>6</Subscript>](NO<Subscript>3</Subscript>)<Subscript>2</Subscript>

[Mn(NH₃)₆](NO₃)₂ crystallizes in the cubic, fluorite (C1) type crystal lattice structure (Fm \( \overline{3} \) m) with a = 11.0056 Å and Z = 4. Two phase transitions of the first-order type were detected. The first registered on DSC curves as a large anomaly at T _C1 ^h  = 207.8 K and T _C1 ^c  = 207.2 K, and the second registered as a smaller anomaly at T _C2 ^h  = 184.4 K and T _C2 ^c  = 160.8 K (where the upper indexes h and c denote heating and cooling of the sample, respectively). The temperature dependence of the full width at half maximum of the band associated with the δ_s(HNH)F_1u mode suggests that the NH₃ ligands in the high temperature and intermediate phase reorientate quickly with correlation times in the order of several picoseconds and with activation energy of 9.9 kJ mol^?1. In the phase transition at T _C2 ^c probably only a some of the NH₃ ligands stop their reorientation, while the remainders continue to reorientate quickly with activation energy of 7.7 kJ mol^?1. Thermal decomposition of the investigated compound starts at 305 K and continues up to 525 K in four main stages (I–IV). In stage I, ²/₆ of all NH₃ ligands were seceded. Stages II and III are connected with an abruption of the next ²/₆ and ¹/₆ of total NH₃, respectively, and [Mn(NH₃)](NO₃)₂ is formed. The last molecule of NH₃ per formula unit is freed at stage IV together with the simultaneous thermal decomposition of the resulting Mn(NO₃)₂ leading to the formation of gaseous products (O₂, H₂O, N₂ and nitrogen oxides) and solid MnO₂.     

A fast determination of yohimbine in pharmaceuticals by micellar electrokinetic chromatography

A method for the fast determination of yohimbine, a potent adrenoreceptor antagonist used for the treatment of sexual dysfunctions, is proposed in this article. MEKC under basic and acidic conditions (sodium borate, pH 9.5 and sodium phosphate, pH 2.5) with SDS was developed. The effect of the experimental parameters, e.g. pH, SDS concentration and injection time, on yohimbine migration was also studied. Both methods were validated in terms of linearity, limits of detection and quantification, accuracy, and precision using caffeine as an internal standard. The application for the determination of yohimbine in hand-made medicaments is also investigated in this study.      

Small Noncytotoxic Carbon Nano‐Onions: First Covalent Functionalization with Biomolecules

Small carbon nano‐onions (CNOs, 6–8 shells) were prepared in high yield and functionalized with carboxylic groups by chemical oxidation. After functionalization these nanostructures were soluble in aqueous solutions. 3‐(4,5‐dimethylthiazol‐2‐yl)‐5‐(3‐carboxymethoxyphenyl)‐2‐(4‐sulfophenyl)‐2 tetrazolium (MTS) tests showed excellent cytocompatibility of all CNOs analyzed at 30 and 300 μg mL^?1, so these carbon nanostructures can be safely used for biological applications. The first covalent functionalization of oxidized CNOs (ox‐CNOs) with biomolecules, by using biotin–avidin interactions is reported here. Multilayers were prepared on a gold surface by layer‐by‐layer assembly and the process was monitored by surface plasmon resonance (SPR) spectroscopy and atomic force microscopy (AFM). Covalent binding of molecules to the short amine‐terminated organosulfur monolayers was assessed by Fourier transform infrared spectroscopy using total attenuated reflactance mode (FT‐IR/HATR).