Design of a Simple Integrated Coupler for SPP Excitation in a Dielectric Coated Ag Thin Film

A simple integrated coupler is proposed for the efficient excitation of surface plasmon polariton （SPP） mode in a thin metal film. The SPP mode is generated in a single Ag-dielectric interface by the incident field and coupled with an Ag thin film. The coupling efficiency at different wavelengths using two different dielectrics, gallium lanthanum sulfide （GLS） and aluminum gallium arsenide （AIGaAs） is calculated by analyzing the SPP propagation dynamics with the finite difference time domain method. A maximum coupling efficiency of 70~ is obtained at a wavelength of 46Ohm when GLS is used, whereas the corresponding value obtained for A1GaAs is 60~o at 56Onto. The proposed structure can be used to excite SPPs in a nano-thin film from an external bulky source and is easier to fabricate since a single interface metal-dielectric configuration is used to excite the metal-thin film.     

Impact of end-capped engineering on the optoelectronic characteristics of pyrene-based non-fullerene acceptors for organic photovoltaics

Pyrene-based molecules are being explored as prospective fullerene-free acceptors for organic solar cells (OSCs), due to their easy accessibility, structural planarity, and excellent electron delocalization. In this work, we successfully designed and analyzed pyrene-based acceptor materials (QL1–QL8) to investigate their photophysical and electro-optical parameters. Various geometric parameters were computed at the MPW1PW91/6-31G(d,p). Advanced quantum chemical approaches were employed to characterize the molecules. All the tailored molecules (QL1–QL8) exhibit a lower bandgap than the reference (R), signifying their superiority. Among these, QL8 was found to have a maximum absorption (λ_max) at 791.37 nm and an optical bandgap (E_LUMO − E_HOMO) minimum of 2.11 eV. Redshifted absorption spectra are observed in both gaseous and solvent phases for all the designed (QL1–QL8) molecules in contrast to R. Among these, QL4 exhibits the highest light harvesting efficiency (0.9826), and open-circuit voltage. A detailed donor–acceptor investigation of QL8/PBDB-T revealed the marvelous charge switching at the donor–acceptor interface. The approach used in this study is anticipated to facilitate the manufacturing of highly efficient OSC molecules.     

Mechanism of anation of chromium (III) by L-lysine

The kinetics of L-lysine anation of aquachromium(III) ions have been investigated in the acidity range 5.6 ≤ 10⁵[H⁺] ≤ 31.6 mol dm⁻. The reaction takes place with outer-sphere association between Cr³⁺/CrOH²⁺ and H₂L⁺ (L =⁺HGCH (⁺NH₃)(CO ₂ ^t- ), G being the side chain) followed by transformation of the outer-into an inner-sphere complex by slow interchange. The results are discussed in relation to the data of analogous systems and it is concluded that anation of [Cr(H₂O)₆]^{3 +} follows anI _a path whereas that of [Cr(H₂O)₅OH]_{2 +} follows anI _d path.     

Coupling of Bifunctional CoMn‐Layered Double Hydroxide@Graphitic C3N4 Nanohybrids towards Efficient Photoelectrochemical Overall Water Splitting

The development of durable, low‐cost, and efficient photo‐/electrolysis for the oxygen and hydrogen evolution reactions (OER and HER) is important to fulfill increasing energy requirements. Herein, highly efficient and active photo‐/electrochemical catalysts, that is, CoMn‐LDH@g‐C₃N₄ hybrids, have been synthesized successfully through a facile in situ co‐precipitation method at room temperature. The CoMn‐LDH@g‐C₃N₄ composite exhibits an obvious OER electrocatalytic performance with a current density of 40 mA cm^?2 at an overpotential of 350 mV for water oxidation, which is 2.5 times higher than pure CoMn‐LDH nanosheets. For HER, CoMn‐LDH@g‐C₃N₄ (η₅₀=?448 mV) requires a potential close to Pt/C (η₅₀=?416 mV) to reach a current density of 50 mA cm². Furthermore, under visible‐light irradiation, the photocurrent density of the CoMn‐LDH@g‐C₃N₄ composite is 0.227 mA cm^?2, which is 2.1 and 3.8 time higher than pristine CoMn‐LDH (0.108 mA cm^?2) and g‐C₃N₄ (0.061 mA cm^?2), respectively. The CoMn‐LDH@g‐C₃N₄ composite delivers a current density of 10 mA cm^?2 at 1.56 V and 100 mA cm^?2 at 1.82 V for the overall water‐splitting reaction. Therefore, this work establishes the first example of pure CoMn‐LDH and CoMn‐LDH@g‐C₃N₄ hybrids as electrochemical and photoelectrochemical water‐splitting systems for both OER and HER, which may open a pathway to develop and explore other LDH and g‐C₃N₄ nanosheets as efficient catalysts for renewable energy applications.     

Microbial transformation of (+)-adrenosterone

The microbial transformation of (+)-adrenosterone (1) by Cephalosporium aphidicola afforded three metabolites identified as androsta-1,4-diene-3,11,17-trione (2), 17beta-hydroxyandrost-4-ene-3,11-dione (3) and 17beta-hydroxyandrosta-1,4-diene-3,11-dione (4). The fermentation of 1 with Fusarium lini also produced metabolites 2 and 4, while the fermentation with Trichothecium roseum afforded metabolite 3. The structures of transformed products were determined by spectroscopic methods.     

Determination of 2-(diethylamino)-N-(2,6-dimethylphenyl) acetamide in a gel pharmaceutical formulation by high-performance liquid chromatography

An isocratic reversed-phase high performance liquid chromatographic method is developed and validated for the determination of 2-(diethylamino)-N-(2,6-dimethylphenyl) acetamide (0.3%, w/w) in a gel formulation. The chromatographic separation is achieved with potassium phosphate buffer (pH 7.0)-acetonitrile (47:53, v/v) as mobile phase, a C(18) column, and UV detection at 254 nm. The calibration curve is linear (r(2) = 1.000) from 20-140% of the analytical concentration of 1.4 microg/mL. The mean percent relative standard deviation values for intra- and interday precision studies are < 1%. The recovery ranges 99.95-100.23% from a gel formulation. The method is specific and successfully routinely used in quality control for the analysis of bulk gel samples and final product release.     

Validation of high-performance liquid chromatography methods for pharmaceutical analysis. Understanding the differences and similarities between validation requirements of the US Food and Drug Administration,the US Pharmacopeia and the International Conference on Harmonization

One of the most critical factors in developing pharmaceutical drug substances and drug products today is ensuring that the HPLC analytical test methods that are used to analyze the products generate meaningful data. The US Food and Drug Administration (FDA) and United States Pharmacopeia (USP) have each recognized the importance of this to the drug development process and have separately increased validation requirements in recent years. A third source, the International Conference on Harmonization (ICH), has added requirements that, when combined with the previous two sources, have led to three different sets of validation requirements leaving the industry in a state of confusion. This paper is written to clear up the confusion over the validation requirements that are presented by each of these three sources.     

Development and validation of a HPLC method for 4,7-phenanthroline-5,6-dione I and identification of its major impurity by HPLC-MS-APCI

In this study, the development and validation of an analytical method for the assay of 4,7-phenanthroline-5,6-dione I (dione I) using high-performance liquid chromatography (HPLC) and the determination of its synthetic impurities by employing the method in HPLC-mass spectrometry with atmospheric-pressure chemical ionization and photodiode-array UV detection is reported. The results show that dione I is eluted as a spectrally pure peak resolved from its impurities. 5-Bromo,4-7-phenanthroline is identified as the main impurity. This is supported by elemental analysis of the dione I, which demonstrated the presence of bromine. Validation parameters such as specificity and selectivity, linearity, accuracy, precision, limit of detection (LOD), limit of quantitation (LOQ), ruggedness, stability, and system suitability, which are evaluated for this method. The LOD and LOQ are 2.0 microg/mL and 50 microg/mL with a 0.50% relative standard deviation (%RSD), respectively. The calibration curves showed good linearity over the concentration range of 0.05-1.50 mg/mL. The correlation coefficient is > 0.9991 in each case. The %RSD values for intra- and interday precision studies are < 0.40%.     

A modified,economical and efficient synthesis of variably substituted pyrazolo[4,3‐d]pyrimidin‐7‐ones

1‐Methyl‐3‐propyl‐1H‐pyrazole‐5‐carboxylic acid ( 3 ) was exclusively brominated at the 4‐position by bromine in the dark. Brominated product 8 was then converted into 1‐methyl‐3‐propyl‐1H‐pyrazole‐5‐car‐boxamide 9 by successive treatment with thionyl chloride and ammonium hydroxide. Carboxamide 9 was treated with various aroyl amides under microwave (MW) irradiation to afford 4‐aroylamino‐1‐methyl‐3‐propyl‐1H‐pyrazole‐5‐carboxamides 10‐22 and 5‐aryl‐1‐methyl‐3‐propyl‐1,6‐dihydro‐1H‐pyrazolo[4,3‐d]pyrimidin‐7‐ones 23‐35. The 1H‐pyrazole‐5‐carboxamides 10‐22 were also converted to pyrimidinones 23‐35 either by conventional heating or by MW irradiation. However, MW irradiation method gives excellent yields in very short time.     

A kinetic study of the complex formation between aquachromium(III) ions and L-iso-leucine

Summary The kinetics of complex formation between aquachromium(III) ions and L-iso-leucine have been studied spectrophotometrically. Effects of varying the total chromium(III), total amino acid and H⁺ concentrations, ionic-strength, temperature and % EtOH on the k_ohs were determined. The results are best accounted for by outer-sphere complexation equilibria involving HL (the amino acid zwitterion) and [Cr(H₂O)₆]³⁺/[Cr(H₂O)₅OH]²⁺ which precede anations. A rate-equation is established which involves K_os1, K_os2, k₁, k₂ (the respective outer-sphere complexation and interchange rate constants with [Cr(H₂O)₆]³⁺ and [Cr(H₂O)₅OH]²⁺), K_a and K_h (the acid-dissociation constants of H₂L⁺HL and [Cr(H₂O)₆]³⁺ [Cr(H₂O)₅OH]²⁺ pairs). The proposed mechanism is I_a for the path involving hexaaqua- and I_d for that involving hydroxopentaaquachromium(III).