Estimation of Metformin Drug for the Diabetes Patients by Simple,Quick and Cheap Techniques within the Formation of Colored Charge Transfer Complexes

Metformin (Met) is a drug developed for the treatment of patients with type Ⅱ diabetes. Recently, Met estimation in pharmaceutical formulations and human fluids has gained a growing interest. To extend requisite data that can be used to assessment of Met quantitatively based on charge-transfer (CT) complexation, the present study describes the synthesis and characterization of CT complexes that formed between drug Met and the organic π-acceptors picric acid (PA), chloranilic acid (CLA), chloranil (CHL), 7,7’,8,8’-tetracyanoquinodimethane (TCNQ), and dichlorodicyanobenzoquinone (DDQ). The properties of the formed CT complexes were investigated by elemental, spectral (UV-visible, IR, and Raman spectroscopies), thermal (TG) and morphological (SEM) studies. IR results indicated that the complexation of Met with either PA or CLA acceptors occurs through proton transfer interaction, whereas its complexation with CHL, TCNQ, or DDQ acceptors occurs through n→π* interaction.     

Magnetoresistivity in a tilted magnetic field in p-Si/SiGe/Si heterostructures with an anisotropic g-factor. Part II

The magnetoresistance components ??xx and ??xy are measured in two p-Si/SiGe/Si quantum wells that have an anisotropic g-factor in a tilted magnetic field as a function of the temperature, field, and tilt angle. Activation energy measurements demonstrate the existence of a ferromagnetic-paramagnetic (F-P) transition for the sample with the hole density p = 2 × 10¹¹ cm^?2. This transition is due to the crossing of the 0?? and 1?? Landau levels. However, in another sample with p = 7.2 × 10¹⁰ cm^?2, the 0?? and 1?? Landau levels coincide for angles ?? = 0?C70°. Only for ?? > 70° do the levels start to diverge which, in turn, results in the energy gap opening.     

Structural and electrochemical properties of LiNi1/3Co1/3Mn1/3O2 material prepared by a two-step synthesis via oxalate precursor

LiNi_1/3Co_1/3Mn_1/3O₂ (LNMCO) powders were formed by a two-step synthesis including preparation of an oxalate precursor by ??chimie douce?? followed by a solid-state reaction with lithium hydroxide. The product was characterized by TG-DTA, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), Raman spectroscopy, electron spin resonance (ESR), and SQUID magnetometry. XRD data revealed well-crystallized layered LNMCO with ??-NaFeO₂-type structure (R-3?m space group). Morphology studied by SEM and TEM shows submicronic particles of 400?C800?nm with a tendency to agglomerate. The local structure investigated by vibrational spectroscopy (FTIR, Raman), ESR, and SQUID measurements confirms the well-crystallized lattice with a cation disorder of 2.6% Ni²⁺ ions in Li(3b) sites. Electrochemical tests were carried out in the potential range 2.5?C4.5?V vs. lithium metal on samples heated at 900?°C for 12?h. Initial discharge capacity is 154 mAh/g at C/5, while a capacity of 82 mAh/g is still delivered at 10 C by the two-step synthesized LiNi_1/3Co_1/3Mn_1/3O₂ as cathode material.     

Spectroscopic and thermal studies on charge-transfer complexes of perhydroisoquinoline with p-chloranil, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, and 7,7′,8,8′-tetracyanoquinodimethane

Charge-transfer interactions of perhydroisoquinoline (PHIQ) with 2,3-dichloro-5,6-dicyano-1,4- benzoquinone (DDQ), p-chloranil (CHL), and 7,7′,8,8′-tetracyanoquinodimethane (TCNQ) in chloroform as a solvent have resulted in stable complexes with a general formula [(PHIQ)(acceptor)] with a molar ratio of 1:1 (donor:acceptor). Elemental (C, H, N) and thermogravimetric (TGA/DTG) analyses, photometric titration, and electronic, infrared, and ¹H NMR spectra were used to give an idea of the charge-transfer interaction between donating and accepting sites. The Benesi–Hildebrand method and its modification were used to determine an association constant (K) and a molar extinction coefficient (ε).     

Investigation of LiFeAs by means of “break-junction” technique

In our tunneling investigation using Andreev superconductor-normal metal-superconductor contacts on LiFeAs single crystals we observed two reproducible independent subharmonic gap structures at dynamic conductance characteristics. From these results, we can derive the energy of the large superconducting gap ??_L = (2.5?C3.4) meV and the small gap ??_S = (0.9?C1) meV at T = 4.2 K for the T _C ^local ?? (10.5?C14) K (the contact area critical temperature which deviation causes the variation of ??_L). The BCS-ratio is found to be 2??_L/k _B T _C = 4.6?C5.6, whereas 2??_S/k _B T _C ? 3.52 results from induced superconductivity in the bands with the small gap.     

Local atomic and magnetic structures of nanocrystalline Fe75Cr10B15 alloy

The crystal, local atomic and magnetic structures of Fe₇₅Cr₁₀B₁₅ alloys annealed at 440?C473°C for 5 min have been studied using X-ray diffraction and ⁵⁷Fe M?ssbauer spectroscopy. At the annealing temperature T _a = 440°C, nanocrystals of the ??-Fe phase (??1%) precipitate in the amorphous matrix of the alloy. The complete crystallization of the amorphous alloy occurs at T _a = 473°C with the formation of ??-Fe nanocrystals 26 ± 2 nm in size and nanocrystals of tetragonal boride t-Fe₃B 47 ± 2 nm in size. It has been found that chromium atoms are located in nanocrystals of the ??-Fe and y-Fe₃B types. The distribution functions of hyperfine fields in the nanocrystalline Fe₇₅Cr₁₀B₁₅ alloy reconstructed from the M?ssbauer spectra (at T _a = 473°C) show that there are three allowed states of iron atoms in the ??-Fe phase and three equally probable crystallographic nonequivalent states of iron in the t-(Fe,Cr)₃B phase. The chromium concentration x in the ??-Fe(Cr) phase is found to be ??10 at %. The substitution of chromium atoms for iron atoms in t-Fe₃B substantially decreases local magnetic moments of the iron atoms.     

Evolution of Co n Al clusters and chemisorption of hydrogen on Co n Al clusters

Multiwall carbon nanotubes (MWCNTs, 1?C3???M in length and 20?C25?nm in diameter) were initially functionalized with a 2,2??:6??2??-terpyridine-chelated ruthenium(II) complex by covalent amidation. The resulting functionalized ruthenium MWCNTs (RuMWCNTs, 1?C2???M in length and 10?C20?nm in diameter) were characterized by thermogravimetric analysis, X-ray photoelectronic spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and scanning electron microscopy (SEM). Thermogravimetric experiments of RuMWCNTs show that the functional group coverage of terpyridine?Crutheniun?Cterpyridine (tpy?CRu?Ctpy) is 0.7036?mmol/1.0?g carbon. The XPS results show N1s and Ru3d^5/5 signals, confirming the presence of tpy?CRu?Ctpy groups on the surface of MWCNTs. The FTIR spectra of the RuMWCNTs display the typical stretching mode of the carboxyl group (amide I) and a combination of amide N?CH and C?CN stretching mode (amide II). The Raman D- and G-line peak intensity ratio of RuMWCNTs (ID/IG 2.21) exceeds that of pristine MWCNTs (ID/IG 1.93), suggesting covalent bonding of tpy?CRu?Ctpy to MWCNTs and supporting the disruption of the graphitic integrity due to the proposed covalent functionalization. High-resolution SEM images confirm that tpy?CRu?Ctpy moieties are interconnected or attached as aggregated structures (100?C200-nm range) on the surfaces of the carbon nanotubes after functionalization. The electrical property of RuMWCNTs depicts higher resistance (10.10?M???) than that of OX-MWCNTs (15.38?k??).     

On the mechanism of electromagnetic microwave absorption in superfluid helium

In experiments on electromagnetic (EM) wave absorption in the microwave range in superfluid (SF) helium [1?C3], a narrow EM field absorption line with a width on the order of (20?C200) kHz was observed against the background of a wide absorption band with a width of 30?C40 GHz at frequencies f ₀ ?? 110?C180 GHz corresponding to the roton gap energy ?? _r (T) in the temperature range 1.4?C2.2 K. Using the so-called flexoelectric mechanism of polarization of helium atoms (⁴He) in the presence of density gradients in SF helium (HeII), we show that nonresonance microwave absorption in the frequency range 170?C200 GHz can be due to the existence of time-varying local density gradients produced by roton excitations in the bulk HeII. The absorption bandwidth is determined by the roton-roton scattering time in an equilibrium Boltzmann gas of rotons, which is t _r-r ?? 3.4 × 10^?11 s at T = 1.4 K and decreases upon heating. We propose that the anomalously narrow microwave resonance absorption line in HeII at the roton frequency f ₀(T) = ??r(T)/2??? appears due to the following two factors: (i) the discrete structure of the spectrum of the surface EM resonator modes in the form of a periodic sequence of narrow peaks and (ii) the presence of a stationary dipole layer in HeII near the resonator surface, which forms due to polarization of ⁴He atoms under the action of the density gradient associated with the vanishing of the density of the SF component at the solid wall. For this reason, the relaxation of nonequilibrium rotons generated in such a surface dipole layer is strongly suppressed, and the shape and width of the microwave resonance absorption line are determined by the roton density of states, which has a sharp peak at the edge of the roton gap in the case of weak dissipation. The effective dipole moments of rotons in the dipole layer can be directed either along or across the normal to the resonator surface, which explains the experimentally observed symmetric doublet splitting of the resonance absorption line in an external dc electric field perpendicular to the resonator surface. We show that negative absorption (induced emission) of EM field quanta observed after triggering a Kapitza ??heat gun?? occurs when the occupation numbers for roton states due to ??pumping?? of rotons exceed the occupation numbers of EM field photons in the resonator.     

光谱法研究N—烃基吖啶满和10,10‘—地烃基—9,9’—联二吖烯？…

ＵＶ，ＩＲ，ＥＳＲ和荧光光谱法研究了Ｎ－烃基吖啶满和１０，１０’－二烃基－９，９’－联二吖啶烯与π－电子受体：ＤＤＱ、ＴＣＮＱ、ＴＣＮＥ、ＣＡ的氧化反应过程，提出了它们的氧化反应机理。     

Determination of Aluminum Ion with Morin in a Medium Comprised by Ionic Liquid?CWater Mixtures

In this study we have employed two ionic liquids (ILs) as a new media for the analysis of aluminum in aqueous solutions by spectrofluorimetric method. ILs are liquid salts and they have no measurable vapor pressure up to their thermal decomposition point, >300 ??C. This lack of vapor pressure makes these materials highly attractive for many studies as they can be used as clean solvents. Besides they are promising environments for analysis purposes and optical sensor designs. The results revealed that absorption, excitation and emission spectra of the morin?CAl complex exhibited considerable changes in moieties. The morin?CAl complex was stable at aluminum concentrations below 9.1?mg?L^?1 in 25% 1-butyl-3-methylimidazolium bromide (IL-I)-water binary mixtures. The higher concentrations of IL (>25% by volume) was not suitable for the complex formation thus in pure IL media the complex formation even at high aluminum concentrations was not observed. The complex stoichiometry ratio of aluminum:morin was 2:1 in IL-I-water binary mixtures. The linear concentration range was 0.045?C7.2?mg?L^?1 with a correlation coefficient of r?=?0.9909. The detection limit was found to be 0.036?mg?L^?1. Cu²⁺, Mn²⁺ and PO ₄ ^3? ions exhibited less interfering effect in presence of IL-I and the tolerance limit of Cu enhanced 10 times when compared with ethanol.     

Electrochemical performance of lead acid battery using ammonium hydrogen sulphate with different alkyl groups

In this work, the application of ionic liquids (ILs)??mono-, bicycyclohexyl, monohexyl and tetrahexyl ammonium hydrogen sulphate??as electrolyte additives on the electrochemical performance of lead acid batteries is proposed. The electrochemical behaviour of Pb?C1.66% Sb?C0.24% Sn alloy in sulphuric acid solution is investigated in the presence of the mentioned ILs with different numbers of alkyl or cycloalkyl chains. Particularly, the hydrogen and oxygen evolution potential and anodic layer characteristics were studied using cyclic and linear sweep voltammetric methods. The obtained results indicate that hydrogen evolution overpotential of Pb/Sb/Sn alloy in the presence of ILs increases. This overpotential mainly depends on the concentration of ILs and the number of alkyl and cycloalkyl chains on the cations. Also, the difference between the oxygen oxidation potential in anodic and cathodic scans (?E) decreases using different ILs.     

Surface-induced structural modification in ZnO nanoparticles

Cobalt?Ccobalt carbide [Co _x C (x?=?2 or 3)] and cobalt (FCC-Co) microwires have been synthesized using a polyol method in the presence of a high external magnetic field of 4.3?kOe. It was reported before that the synthesis of these particles in the absence of magnetic field leads to the formation of spherical particles. Analysis of the X-ray diffraction (XRD) scans indicates that the synthesized Co _x C wires consist of four phases?? ??-Co, ??-Co, Co₃C, and Co₂C. The percent composition of these phases was 53.3?% Co₃C, 26.8?% Co₂C, 12.5?% ??-Co, and 7.4?% ??-Co. XRD analysis of the as-synthesized cobalt wires shows that it consists of single-phase FCC-Co. Based on Scherrer analysis of the XRD data, the average crystallite sizes of the cobalt carbide and the cobalt particles are 18.5 and 16.3?nm, respectively. Scanning electron microscopy (SEM) studies show that the diameter of Co _x C wires is in the range of 1.6(±0.2)???m with their length varying between 18 and 30???m while the diameter of the cobalt wires is 1.65(±0.1). The SEM results infer that the morphology of the growing particles was controlled by the magnetic field with the applied field directs the growth of the particles into wires. The magnetic measurements indicate a superparamagnetic character of the cobalt wires and a soft ferromagnetic nature of the synthesized Co _x C chains. The degree and field range of the interactions between magnetic domains have been investigated using a Henkel plot.     

Preparation of cytocompatible luminescent and magnetic nanohybrids based on ZnO, Zn0.95Ni0.05O and core@shell ZnO@Fe2O3 polymer grafted nanoparticles for biomedical imaging

ZnO, Zn_0.95Ni_0.05O and core@shell ZnO@??-Fe₂O₃ nanoparticles (NPs) have been prepared by forced hydrolysis in polyol medium and then coated via the ??grafting from?? approach with poly(sodium-4-styrenesulfonate) and poly(sodium-4-styrenesulfonate?Cco?Csodium methacrylate) in the case of ZnO. The surface-initiated atom transfer radical polymerization occurred from the surface-functionalized NPs with ??-bromoisobutyric acid as initiator. The polymer chains were grown from the surface to yield hybrid NPs with a 1?C3-nm thick organic shell. FT-IR, TGA and electron microscopy evidenced the presence of a polymer layer on the surface of NPs. Magnetic and optical properties of bare and coated NPs have been measured. Eventually, the weak cytotoxicity of coated NPs on human endothelial cell allows considering their potentialities as new tools for nanomedicine and biomedical imaging.     

On the intensity of galactic cosmic rays in the inner heliosphere during epochs of minimum solar activity

The behavior of the intensity of cosmic rays of galactic origin in the inner heliosphere (r ?? 10 a. u.) during the minima of solar cycles 20?C24 is considered. The features of cosmic ray characteristics in the last anomalously long and deep minimum of solar cycle 24 (2007?C2010) are discussed.     

阿奇霉素含量的荷移光谱法测定

用分光光度法分别研究了阿奇霉素与7,7,8,8-四氰基对二次甲基苯醌(TCNQ)和氯冉酸(CL)之间的荷移反应。实验表明：阿奇霉素与TCNQ间的反应在丙酮介质中进行,形成的络合物在743和842 nm有两个吸收峰,表观摩尔吸光系数分别是2.7×104 L·mol-1·cm-1和5.0×104 L·mol-1·cm-1;阿奇霉素与氯冉酸的反应在丙酮介质中进行,形成的络合物在530 nm处有吸收峰,表观摩尔吸光系数2.4×103 L·mol-1·cm-1。用摩尔比法和等摩尔连续变化法测得荷移络合物中阿奇霉素与配体的摩尔比均为1∶2。用以上两种方法测定了阿奇霉素片剂中阿奇霉素的含量,相对标准偏差为1.0%～1.4%(n=6),回收率为97%以上,与标准方法比较结果准确。     

Selective Fluorescence Sensing of Deoxycytidine 5��-Monophosphate (dCMP) Employing a Bis(diphenylphosphate)diimine Ligand

A new bis(diphenylphosphate)diimine ligand (BP1) was prepared and evaluated for its ability for selective detection of deoxycytidine 5??-monophosphate (dCMP). BP1 exhibited off-type fluorescence in the presence of dCMP. The fluorescence of BP1 was significantly quenched upon the addition of 2.5?×?10^?4 M dCMP and the detection limit was 1.25?×?10^?5 M in MeCN-H₂O (1:1, v/v). The binding ratio between BP1 and dCMP was determined to be 1:1 with the binding constant of 3.98?±?0.60?×?10^?3 M^?1.     

High-temperature ferromagnetism in Si1 ? x Mn x (x ≈ 0.5) nonstoichiometric alloys

It has been found that the Curie temperature (T _C ?? 300 K) in nonstoichiometric Si_{1 ? x} Mn _x alloys slightly enriched in Mn (x ?? 0.52?C0.55) in comparison to the stoichiometric manganese monosilicide MnSi becomes about an order of magnitude higher than that in MnSi (T _C ?? 30 K). Deviations from stoichiometry lead to a drastic decrease in the density of charge carries (holes), whereas their mobility at about 100 K becomes an order of magnitude higher than the value characteristic of MnSi. The high-temperature ferromagnetism is ascribed to the formation of defects with the localized magnetic moments and by their indirect exchange interaction mediated by the paramagnetic fluctuations of the hole spin density. The existence of defects with the localized magnetic moments in Si_{1 ? x} Mn _x alloys with x ?? 0.52?C0.55 is supported by the results of numerical calculations performed within the framework of the local-density-functional approximation. The increase in the hole mobility in the nonstoichiometric material is attributed to the decay of the Kondo (or spin-polaron) resonances presumably existing in MnSi.     

Optical properties of cyclometalated Pd(II) and Rh(III) complexes based on 2-(4-biphenylyl)-6-phenylbenzoxazole luminophore with ethylenediamine

Using the methods of electronic absorption and emission spectroscopy, we have studied the optical properties of cyclometalated [Pd(C??N)En]CH₃COO and [Rh(C??N)₂En]Cl complexes of 2-(4-biphenylyl)-6-phenylbenzoxazole luminophore with ethylenediamine. We have shown that, along with a bathochromic shift of intraligand spin-allowed ??-??* optical transitions by 1000?C1800 cm^?1, complexes are characterized by the occurrence of long-wavelength bands of a mixed nature (intraligand-metal-ligand charge transfer) in the range of 369??392 nm and by competing intraligand fluorescence (419?C423 nm) and phosphorescence (511?C532 nm) processes under low-temperature (77 K) photoexcitation.     

荷移反应-荧光光谱法测定氟罗沙星

提出了一种基于荷移反应简便可靠地测定氟罗沙星的荧光光谱法,研究了电子受体2,3-二氰-5,6-二氯-1,4-对苯醌(DDQ)与氟罗沙星电子给体之间的荷移反应。实验结果表明,氟罗沙星与DDQ的荷移反应可使氟罗沙星产生显著的荧光增敏效应。其最低检测限为0.1mg·L~(-1),用于片剂中氟罗沙星含量的测定,其回收率为96.6％～99.2％,相对标准偏差为1.9％～2.8％。本文还对荷移反应的机理进行了探讨。     

Relativistic effects in one-dimensional hydrogen atom

The dependence of stationary levels of a Dirac particle in the regularized Coulomb potential V _??(z) = ?q/(|z| + ??) on the cutoff parameter ?? is studied. It is shown that, in 1 + 1 D, the energy spectrum of a Dirac particle in such a potential reveals some specific features which nonanalytically depend on the coupling constant q and are essentially relativistic in nature. These properties turn out to be most important for ?? ? 1, explicitly demonstrating the existence of a physically reasonable energy spectrum for an arbitrarily small ?? > 0 and, at the same time, the absence of regular limit ?? ?? 0 (hence, the absence of a well-defined spectral problem for the Dirac equation without regularization for arbitrary q in 1 + 1 D).