Photodamage and Photoprotection: An In vivo Approach Using Noninvasive Probes

Solar radiations trigger the physiological alteration in skin which progress toward photoaging. Sunscreens are known to be effective against the photodamaging effects of sunlight. The purpose of this study was to evaluate the extent to which aging signs caused by real‐life sunlight exposure could be avoided by comparing various parameters between sun‐exposed and sun‐protected skin using noninvasive probes. Female volunteers (n = 11) after getting their consent were provided with marketed sunscreen product to apply onto their skin for 6 months. Measurements were scheduled every 15 days from the baseline reading for 6 months. Cutometer, Mexameter and Corneometer were used for evaluation of facial skin parameters. Clinical evaluations showed the effects of sunlight exposure on different skin parameters by comparing sun‐protected and unprotected skin, where Gross elasticity (R2), Net elasticity (R5), Viscoelasticity (R6) and Biological elasticity (R7) showed insignificant results, while Hydration, Melanin and Erythema showed significant results. Sun‐exposed skin presented 0.72%, 0.66%, 0.77%, 1.39%, 1.99%, 2.01% and 3.15% changes in R2, R5, R6 and R7, melanin, erythema and hydration, respectively, which were potentially prevented by sunscreen application. Premature aging is inhibited by following photoprotective regimen on routine basis, emphasizing the potential benefit of sunscreen against early aging signs.     

Comparison of flow and batch polymerization processes for production of vinyl ether terpolymers for use in the delivery of siRNA

Synthetic polymers represent a modifiable class of materials that can serve as adjuvants to address challenges in numerous biomedical and medicinal chemistry applications including the delivery of siRNA. Polymer‐based therapeutics offer unique challenges in both synthesis and characterization as compared to small molecule therapeutics. The ability to control the structure of the polymer is critical in creating a therapeutic. Reported herein, are batch and flow polymerization processes to produce amphiphilic terpolymers through a Lewis acid BF₃OEt₂‐catalyzed polymerization. These processes focus on controlling reaction variables, which affect polymer structure in this rapid, exothermic, nonliving cationic polymerization. In addition to analytical characterization of the polymers, the in vivo activity of the polymer‐siRNA conjugates is also highlighted—demonstrating that the method of synthesis does affect the in vivo activity of the resulting polymer conjugate. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1119–1129     

Mechanistic study of protein phosphatase-1 (PP1), a catalytically promiscuous enzyme

The reaction catalyzed by the protein phosphatase-1 (PP1) has been examined by linear free energy relationships and kinetic isotope effects. With the substrate 4-nitrophenyl phosphate (4NPP), the reaction exhibits a bell-shaped pH-rate profile for kcat/KM indicative of catalysis by both acidic and basic residues, with kinetic pKa values of 6.0 and 7.2. The enzymatic hydrolysis of a series of aryl monoester substrates yields a Br?nsted beta(lg) of -0.32, considerably less negative than that of the uncatalyzed hydrolysis of monoester dianions (-1.23). Kinetic isotope effects in the leaving group with the substrate 4NPP are (18)(V/K) bridge = 1.0170 and (15)(V/K) = 1.0010, which, compared against other enzymatic KIEs with and without general acid catalysis, are consistent with a loose transition state with partial neutralization of the leaving group. PP1 also efficiently catalyzes the hydrolysis of 4-nitrophenyl methylphosphonate (4NPMP). The enzymatic hydrolysis of a series of aryl methylphosphonate substrates yields a Br?nsted beta(lg) of -0.30, smaller than the alkaline hydrolysis (-0.69) and similar to the beta(lg) measured for monoester substrates, indicative of similar transition states. The KIEs and the beta(lg) data point to a transition state for the alkaline hydrolysis of 4NPMP that is similar to that of diesters with the same leaving group. For the enzymatic reaction of 4NPMP, the KIEs are indicative of a transition state that is somewhat looser than the alkaline hydrolysis reaction and similar to the PP1-catalyzed monoester reaction. The data cumulatively point to enzymatic transition states for aryl phosphate monoester and aryl methylphosphonate hydrolysis reactions that are much more similar to one another than the nonenzymatic hydrolysis reactions of the two substrates.     

Modulating opto-electronic and magnetic responses of Mo- and Zn-adsorbed LiNbO3 (1 1 1) surface for advanced energy harvesting applications: A comprehensive study

This study aimed to comprehensively investigate the optoelectronic and magnetic properties of Mo, Zn/LiNbO₃ (1 1 1) material. The primary objectives were to understand the potential for manipulating the material's magnetism and to elucidate the origin of spin-polarized states and magnetic moments, particularly with respect to the unpaired d orbitals of Nb, Mo, and Zn atoms. To achieve these objectives, we employed the Pardew–Burke–Ernzerhof (PBE) method within the Generalized Gradient Approximation (GGA + U) framework. This computational approach allowed us to examine the optoelectronic and magnetic characteristics of the material in detail. Our research yielded several key findings that enhance our understanding of Mo, Zn/LiNbO₃ (1 1 1) material. We observed a modest improvement in the material's absorption capacity within the visible spectrum, accompanied by a discernible red-shift. Notably, our study involved the calculation of the dielectric function and refractive constant of the material, revealing a strong correlation between absorption trends and the dielectric constant. Furthermore, our investigation uncovered that Mo, Zn/LiNbO₃ (1 1 1) exhibits distinct conduction and valence bands, with p and d orbitals predominantly contributing to each, respectively. The energy gap of the material falls within a range of 0.30–1.04 eV. A particularly significant finding was the narrower band gap of Mo, Zn/LiNbO₃ (1 1 1) material, which can be attributed to the superposition of Mo-d and Zn-p orbit energy levels with O-p orbit energy levels, ultimately forming a covalent bond. Importantly, our research demonstrated the material's heightened optical absorption within the visible spectrum, suggesting its suitability for various photonic and optoelectronic applications. Additionally, we calculated a wide range of optical characteristics, including the dielectric function, absorption coefficient, energy loss, reflectivity, refractive index, extinction coefficient, and optical conductivity, providing a comprehensive assessment of the material's optical properties.     

On some method for solving a nonlinear heat equation

Some exact solutions to a nonlinear heat equation are constructed. An initial-boundary value problem is examined for a nonlinear heat equation. To construct solutions, the problem for a partial differential equation of the second order is reduced to a similar problem for a first order partial differential equation.     

Producing highly linear polyethylenes by using t‐butyl‐functionalized 2,6‐bis(imino)pyridylchromium(III) chlorides

A new family of t‐butyl substituted chromium(III) chloride complexes ( Cr1 – Cr6 ), bearing 2‐(1‐(2,6‐dibenzhydryl‐4‐t‐butylphenylimino)ethyl)‐6‐(1‐(arylimino)ethyl)pyridine (aryl = 2,6‐Me₂C₆H₃ Cr1 , 2,6‐Et₂C₆H₃ Cr2 , 2,6‐i‐Pr₂C₆H₃ Cr3 , 2,4,6‐Me₃C₆H₂ Cr4 and 2,6‐Et₂‐4‐MeC₆H₂ Cr5 ) or 2,6‐bis(1‐(2,6‐dibenzhydryl‐4‐t‐butylphenylimino)ethyl)pyridine ( Cr6 ), has been synthesized by the reaction of CrCl₃·6H₂O in good yield with the corresponding ligands ( L1 – L6 ), respectively. The molecular structures of Cr2 and Cr6 were characterized by X‐ray diffraction highlighted a distorted octahedral geometry with the coordinated N,N,N ligand and three bonded chlorides around the metal center. On activation with modified methylaluminoxane or triisobutyl aluminum, most of the chromium precatalysts exhibit good activities toward ethylene polymerization and produce linear polyethylenes with high‐molecular weight. In addition, an in‐depth catalytic evaluation of Cr2 was conducted to investigate how cocatalyst type and amount, reaction temperature, and run time affect the catalytic activities and polymer properties. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 1049–1058     

A statistical study of the informational base of biologically active pyridine compounds

A computer analysis of the literature material clarified the types of activity most characteristic for pyridine derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 109–113, January, 1985.     

Asymmetric reduction of aromatic and hetero cyclic ketones by hydrosilylation and hydrogen transfer in the presence of optically active rhodium catalysts

A study has been made of enantioselective hydrosilylation and reduction, by hydrogen transfer, of prochiral alkyl phenyl ketones or alkyl hetaryl ketones over various optically active catalysts. A total of 14 aromatic and heterocyclic carbinols were synthesized with preparative yields of 54–100%. The most effective catalytic systems were found to be complexes of RhCl₃ and [Rh(cod)Cl]₂ with the known optical inductor (S,S)-i-Pr-Pybox, with which we have obtained for the first time a series of heterocyclic secondary alcohols with an enantioselectivity of 20–63%.Latvian Institute of Organic Synthesis, Riga, LV-1006. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 342–358, March, 1996. Original article submitted December 11, 1995.     

Inclusion complexes of prochiral heterocyclic ketones with β-cyclodextrins and their reduction with sodium borohydride

Alkyl(2-furyl), alkyl(2-thienyl), and methyl pyridyl ketones form stoichiometric inclusion complexes with -cyclodextrins. Reduction of these complexes in aqueous solution of Na₂CO₃ at room temperature yields the corresponding secondary alcohols with an optical yield which attains 27%.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1621–1627, December, 1993.     

Quinoline Oximes: Synthesis,Reactions, and Biological Activity. (Review)

Data on the production and the reactions of quinoline aldoximes and ketoximes and their derivatives are reviewed. The synthesis of new heterocycles based on quinoline oximes is examined separately. The main results from investigation of the biological activity of quinoline oximes are presented.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 163–190, February, 2005.