Optimization of the reaction conditions for the preparation of 99mTc-celecoxib and its biological evaluation

Celecoxib was labelled effectively with ^99mTc. The labeling yield was found to be influenced by the amount of celecoxib, the amount of stannous chloride dihydrate, the reaction time, the temperature and the pH of the reaction mixture. The importance of stannous chloride dihydrate arises from its function as a reducing agent for pertechnetate to form complex celecoxib. The suitable amount required to produce high labeling yield of ^99mTc-celecoxib was 500 μg SnCl₂·2H₂O. The pH of the reaction medium was found to play a significant role in this labeling process. The labeling reaction was performed at a neutral medium (pH 7). The labeling reaction proceeds well at room temperature (25 ± 1 °C) and the complex decomposes by heat. The labeled celecoxib (^99mTc-celecoxib) showed a good localization in inflamed foci and a good imaging must be taken 4 h post injection.     

Current–Voltage Characteristics of the Aziridine-Based Nano-Molecular Wires: a Light-Driven Molecular Switch

Using nonequilibrium Green's function formalism combined first-principles density functional theory, we analyze the transport properties of a 4,4-dimethyl-6-(4-nitrophenyl)-2-phenyl-3,5-diaza-bicyclo[3.1.0]hex-2-ene molecular optical switch. The title molecule can convert between closed and open forms by visible or ultraviolet irradiation. The I-V characteristics, differential conductance, on-off ratio, electronic transmission coefficients, spatial distribution of molecular projected self-consistent Hamiltonian orbitals, HOMO-LUMO gaps, effect of electrode materials Y(111)(Y =Au, Ag and Pt) on electronic transport and different molecular geometries corresponding to the closed and open forms through the molecular device are discussed in detail. Based on the results, as soon as possible the open form translates to the closed form, and there is a switch from the ON state to the OFF state(low resistance switches to high resistance). Theoretical results show that the donor/acceptor substituent plays an important role in the electronic transport of molecular devices. The switching performance can be improved to some extent through suitable donor and acceptor substituents.     

Modelling of photodegradation effect on elastic-viscoplastic behaviour of amorphous polylactic acid films

Polylactic acid (PLA) films were subjected to accelerated ultra-violet (UV) ageing. The UV irradiation leads to the alteration of the chemical structure which influences directly the mechanical response of the polymer. The chemical modification of the polymer was followed by gel permeation chromatography. Uniaxial tension tests were conducted at 50 °C and for different strain rates in order to characterize the large deformation response of PLA. The influence of UV irradiation on the alteration of the large deformation response of PLA was examined. A physically based elastic-viscoplastic model was used to describe the mechanical response of virgin PLA. The photodegradation effect was incorporated into the constitutive model to capture the stress-strain behaviour up to failure of aged PLA. To that end, the measured molecular weight was used as a direct input into the model. The model is shown to be in good agreement with experimental results over a wide range of UV irradiation doses.     

Vapor–solid–solid growth of Ge nanowires from GeMn solid cluster seeds

We describe the fabrication of Ge nanowires during a single co-deposition step of Ge and Mn at high temperature. In these experimental conditions, a phase separation occurs and two different phases Ge and Ge_1 ? xMn_x are formed with Ge_1 ? xMn_x in the shape of small clusters distributed randomly in the Ge matrix. Because of the high deposition temperature, a new Ge_1 ? xMn_x phase with low eutectic point is stabilized; this phase is different from the one (commonly Ge₃Mn₅) stabilized at lower temperature. During the growth process at 350 °C, the crystalline clusters remain solid but they are highly mobile and can float at the surface, serving as seeds to direct the growth of crystalline Ge nanowires from the vapor. The sketch steps of NWs formation are first the phase separation with formation of specific Ge_1 ? xMn_x critical nuclei with low eutectic point and second the growth of Ge NWs directed by the Ge_1 ? xMn_x solid cluster seeds. Ge NWs growth is forced along particular crystalline axis by the cluster seeds that lower the interfacial energy Ge/Ge_1 ? xMn_x and the energy formation of the germanium crystal stabilizes the cluster position at the tip of the NWs. The density of NWs can be tuned by varying the nominal Mn concentration since this density is related to the number of clusters with the specific Ge_1 ? xMn_x phase (with low eutectic point). The single step MBE process presented here has the main advantage to fully avoid any incorporation of unintentional impurity into Ge nanowires (apart from Mn atoms) and could be applied to several other systems. This work also provides new insights into the vapor–solid–solid growth mechanisms of Ge NWs.     

Synthesis and In-Vivo Evaluation of Benzoxazole Derivatives as Promising Anti-Psoriatic Drugs for Clinical Use

2-(4-Chlorophenyl)-5-benzoxazoleacetic acid (CBA) and its ester, methyl-2-(4-chloro-phenyl)-5-benzoxazoleacetate (MCBA), were synthesized, and their structures were confirmed by ¹HNMR, IR, and mass spectrophotometry. The anti-psoriatic activities of CBA and MCBA were tested using an imiquimod (IMQ)-induced psoriatic mouse model, in which mice were treated both topically (1% w/w) and orally (125 mg/kg) for 14 days. The erythema intensity, thickness, and desquamation of psoriasis were scored by calculating the psoriasis area severity index (PASI). The study also included the determination of histopathological alterations in the skin tissues of treated mice. Topical and oral administration of CBA and MCBA led to a reduction in erythema intensity, thickness, and desquamation, which was demonstrated by a significant decrease in the PASI value. In addition, skin tissues of mice treated with CBA and MCBA showed less evidence of psoriatic alterations, such as hyperkeratosis, parakeratosis, scale crust, edema, psoriasiform, and hyperplasia. After administration of either topical or oral dosing, the anti-psoriatic effects were found to be stronger in MCBA-treated than in CBA-treated mice. These effects were comparable to those produced by Clobetasol propionate, the reference drug. This drug discovery could be translated into a potential new drug for future clinical use in psoriasis treatment.     

Experimental mode coupling analysis in optical waveguides for sensor and component optimization

A computer controlled mode coupling analyser is conceived and described in detail to characterize and to analyse mode coupling in all known kinds of cylindrical, multimode, step index, optical waveguides (CMSIOWs) by experimental measurement. These waveguides can be present in many ways like simple fibres, multimode fibre-optic sensors (MFOS) or other optical components like couplers or modulators. The computer processed results of measurements lead to transfer matrices and modulation transfer matrices. The transfer matrices describe the light distribution in the far field of these waveguides depending on the direction and power of the light that is injected into it. By visualizing the modulation transfer matrices in the form of mesh diagrams, the influence of external physical parameters, like a measured variable, on the mode coupling mechanisms inside CMSIOWs can be shown directly. The computer controlled mode coupling analyser will make the optimization of MFOS more efficient and, moreover, it will ease modelling of CMSIOWs and define their properties. The potential field of applications for the mode coupling analyser will be in engineering and optimization of intrinsic multimode fibre-optic sensors and their components.     

Group IVB metallocene poly(ether ester) polymers containing alpha-cyano-4-hydroxycinnamic acid that act as self-matrix materials in MALDI MS

Polymers derived from reacting Group IVB metallocene dihalides and the matrix alpha-cyano-4-hydroxycinnamic acid act as their own matrix agent when performing MALDI MS. Ion fragments containing two repeat units and greater are formed. The results are similar to those obtained employing graphite as the matrix material. The advantage of employing graphite as a comparative standard is that non-interfering ion fragment clusters are not produced by graphite. This is the second report of the inclusion of alpha-cyano-4-hydroxycinnamic acid into a condensation polymer and the use of the polymer itself as a matrix material indicating that this approach can be successfully applied to other systems. The addition of graphite as a matrix material allows the mass range to increase for the reflective mode.     

The anodic reactivity of 4,4′-dimethoxychalcone: a synthetic and mechanistic investigation

The anodic oxidation of the 4,4′-dimethoxychalcone (DMC) was investigated by different electrochemical methods at a platinum working electrode and in acetonitrile as a solvent. The DMC exhibited a single irreversible anodic peak around 1.6 V versus Ag/AgCl. On the time scale of cyclic voltammetry experiments, the highly reactive radical cation issued from the first electron transfer underwent a second order rate-limiting reaction. The potential imposed electrolyses of DMC led to the formation of a semi-conducting oligomer with 40 % yield. Using different physico-chemicals methods, the structural study confirmed the formation of an o-phenylenevinylene oligomer. The values of the corresponding optical and electrochemical band gaps were calculated to be 3.15 and 2.86 eV, respectively. Finally, a mechanism for the DMC electro-oligomerization was proposed on the basis of the obtained results.