Influence of substrate temperature and Cobalt concentration on structural and optical properties of ZnO thin films prepared by Ultrasonic spray technique

Pure and Cobalt doped zinc oxide were deposited on glass substrate by Ultrasonic spray method. Zinc acetate dehydrate, Cobalt chloride, 4-methoxyethanol and monoethanolamine were used as a starting materials, dopant source, solvent and stabilizer, respectively. The ZnO samples and ZnO:Co with Cobalt concentration of 2 wt.% were deposited at 300, 350 and 400 °C. The effects of substrate temperature and presence of Co as doping element on the structural, electrical and optical properties were examined. Both pure and Co doped ZnO samples are (0 0 2) preferentially oriented. The X-ray diffraction results indicate that the samples have polycrystalline nature and hexagonal wurtzite structure with the maximum average crystallite size of ZnO and ZnO:Co were 33.28 and 55.46 nm. An increase in the substrate temperature and presence doping the crystallinity of the thin films increased. The optical transmittance spectra showed transmittance higher than 80% within the visible wavelength region. The band gap energy of the thin films increased after doping from 3.25 to 3.36 eV at 350 °C.     

A Study of the Thermal Hysteresis in AgNO3

The reversible phase transformation of AgNO₃ is studied. Dielectric constant, d.c. resistivity, differential thermal analysis (DTA) and dilatometric measurements show the occurrence of a reversible phase transition II→I at 160°C with heat of transformation H = 0.78 kcal/mol. The thermal hysteresis in this reversible transformation is examined, the magnitude of the temperature hysteresis does not exceed 12°C. An acceptable agreement is observed between the measured values of the transition temperature obtained by three different experimental techniques. The dilatometric analysis shows that this transition is accompanied by thermal shrinkage with relative shrinkage coefficient 8 × 10^?4. Thermal analysis are also used to get thermodynamic and kinetic data of this phase transition. The temperature dependence of the dielectric constant and d.c. resistivity for single crystals as well as polycrystalline samples of AgNO₃ have clearly located and confirm the phase transitions II→I→II with a strong support to its thermal hysteresis character. The conduction mechanism is found to be activated by energy 0.12 eV for phase I and 0.36 eV for phase II. The observed thermal behaviour of the various measured parameters is attributed to orientational disorder of the nitrate group leading to an order-disorder phase transition which is reported here for first time in AgNO₃.     

Kinetic,isotherm, and mechanism investigations of the removal of nitrate and nitrite from water by the synthesized hydrotalcite Mg–Al

Research on Chemical Intermediates - The objective of this work is to test the effectiveness of hydrotalcite as an adsorbent for the retention of nitrate and nitrite ions and to study the influence...     

Thermal changes in the optical properties of SnSxSe2−x crystals

Optical measurements on crystals in the series SnS_xSe_2?x for 0 ? x ? 2, have yielded information on the changes in the ordinary refractive index $\text{Δn}\text{ΔT}$ and the energy gap $\text{ΔEg}\text{ΔT}$ in the temperature range 125–425 K. The coefficient $\text{Δn}\text{ΔT}$ has values +40 to +160 × 10^?6K^?1 and this confirms that covalent bonding predominantly exists in these materials. The coefficient $\text{ΔEg}\text{ΔT}$ remains fairly consistent for all values of x with an average value of -8.0×10^-4eV K^-1.     

Pre-organization of the core structure of E-selectin antagonists

A new class of N-acetyl-D-glucosamine (GlcNAc) mimics for E-selectin antagonists was designed and synthesized. The mimic consists of a cyclohexane ring substituted with alkyl substituents adjacent to the linking position of the fucose moiety. Incorporation into E-selectin antagonists led to the test compounds 8 and the 2'-benzoylated analogues 21, which exhibit affinities in the low micromolar range. By using saturation transfer difference (STD)-NMR it could be shown that the increase in affinity does not result from an additional hydrophobic contact of the alkyl substituent with the target protein E-selectin, but rather from a steric effect stabilizing the antagonist in its bioactive conformation. The loss of affinity found for antagonists 10 and 35 containing a methyl substituent in a remote position (and therefore unable to support to the stabilization of the core) further supports this hypothesis. Finally, when a GlcNAc mimetic containing two methyl substituents (52 and 53) was used, in which one methyl was positioned adjacent to the fucose linking position and the other was in a remote position, the affinity was regained.     

Urease inhibition and anti-leishmanial assay of substituted benzoylguanidines and their copper(II) complexes

A series of N,N',N'-trisubstituted guanidines (1-6) and their copper(II) complexes, [κ(2)(O,N)-C(6)H(5)CONHC(NHC(6)H(4)Cl)NR](2)Cu(ii) (R = iso-propyl (1a), n-butyl (2a), sec-butyl (3a), tert-butyl (4a), benzyl (5a), and para-tolyl (6a)) were synthesized and characterized using elemental analysis, FTIR and NMR spectroscopy. DFT studies were used to assess the location of the protons in the free ligands. However, calculations have shown that, in all cases, hydrogen bonding from either N-H group gives conformations that are very similar in energy. Single crystal XRD studies were used to characterize ligands 1 and 4 and the related complexes 1a and 4a. The structures reveal that these complexes are mononuclear in the solid state and that copper adopts a regular square planar geometry. In both metallic species, the N, N', N'-trisubstituted guanidine ligands chelate the Cu(II) atom using the oxygen and one nitrogen. The synthesized compounds were investigated for urease inhibition using thiourea as a standard drug. Most complexes exhibit a better activity than the respective guanidines and compound 1a was found to be the most active with IC(50) = 9.83 ± 0.07 μM (the IC(50) for thiourea is 21.0 ± 0.1 μM). The species were also screened for their anti-leishmanial activity. However, all of the compounds were devoid of any significant activity.     

Coordination compounds of indium : XXXVI. The direct electrochemical synthesis of neutral and anionic organoindium halides

The electrochemical oxidation of indium metal in cells of the type leads to the formation of RInX₂ compounds; if 2,2′-bipyridine is also present, the products are the adducts RInX₂·bipy (R = CH₃, C₂H₅, C₆H₅, C₆H₅CH₂, C₆F₅; X = Cl, Br, I (not all combinations)). When R′₄NX is present instead of bipy, the products are the salts R′₄N[RInX₃]. The electrochemical oxidation apparently proceeds via the general mechanism discussed previously. Anomalous results with CH₃I or C₂H₅I are discussed in the light of the known solution chemistry of organoindium(III) compounds.     

Does the reagent gas influence collisional activation when performing in situ chemical ionization with an ion trap mass spectrometer?

Users of ion trap mass spectrometers frequently develop methods that associate chemical ionization with tandem mass spectrometry detection. With apparatus using internal ionization, the chemical reagent is present in the trap during the collision induced dissociation (CID) step and one may wonder if the reagent influences the fragmentation ratios in MS/MS. We report a comparison of the fragmentation ratios of protonated molecules when using the most common reagents (methane, ammonia, methanol, acetonitrile, isobutane) for performing in situ chemical ionization. Four molecules were chosen in the medical field to serve as models: alprazolam, diazepam, flunitrazepam and acetaminophen. In the non-resonant CID mode, the influence of the reagent mass is clearly seen in spite of its low partial pressure in the ion trap; the reagent acts as a "heavy target": the degree of fragmentation increases with the molecular weight of the reagent. In the resonant CID mode, there is no evident correlation between the fragmentation ratio of MH(+) ions and the nature of the CI reagent; a slight shift of the secular frequency of the precursor ion, which tends to reduce the CID efficiency, could compensate for the "heavy target" effect underscored in the non-resonant mode.     

Promising photoluminescence optical approach for triiodothyronine hormone determination based on smart copper metal–organic framework nanoparticles

A copper metal–organic framework nanoparticles (Cu‐MOF‐NPs) synthesized via simple technique. The prepared Cu‐MOF‐NPs nanoparticles were further characterized using ¹H‐NMR, FE‐SEM/EDX and thermal study (DSC/TGA). The FE‐SEM/EDX, thermal analysis, and NMR spectrum data with the other analysis support the nano‐Cu‐MOF structure and the monomeric unit (n[Cu (AIP)₂(APY)(H₂O)₂].4H₂O) of Cu‐MOF‐NPs. The photoluminescence (PL) studies of triiodothyronine hormone (T3) based on the prepared Cu‐MOF‐NPs investigated. The results revealed that the Cu‐MOF‐NPs might be used as a biosensor in the determination of triiodothyronine hormone (T3) in biological fluids through a significant quenching of the photoluminescence intensity of Cu‐MOF‐NPs at excitation wavelength 492 nm. The calibration plot achieved over the concentration range 0.0–200.0 ng/dL T3 hormone with a correlation coefficient 0.996 and limit of detection (LOD) and quantification (LOQ) 0.198 and 0.60 ng/dL, respectively. The PL spectra are indicating that Cu‐MOF‐NPs has highly selective sensing properties for T3 hormone without interfering with other human many hormones types. This approach considered a promising analytical tool for early diagnosis of the cases of thyroid disease. The mechanism of quenching between the Cu‐MOF‐NPs, and T3 hormone studied. The mechanism was a dynamic type and obtained due to the energy transfer mechanism.