Polymer-supported nitroxyl radical catalyst for selective aerobic oxidation of primary alcohols to aldehydes

PS-TEMPO, a polymer-supported 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO), was successfully applied as a recyclable, active and selective catalyst for the oxidation of primary aliphatic and benzylic alcohols to aldehydes by molecular oxygen in the presence of Co(NO3)2 and Mn(NO3)2 as co-catalysts.     

Ritter Reaction of 1‐Aryl‐1‐Fluoro‐2‐Haloethanes

Fluorinated phenethyl bromides 1,2 , and 3 , prove to be totally inert under Ritter reaction conditions in the presence of either SnCl₄ or AgNO₃, due to the strong deactivation by the gem‐difluoro unit. Subjecting 2‐bromo‐1‐fluoro‐1‐phenylethane to SnCl₄ in MeCN at elevated temperatures led to formation of 2‐methyl‐4‐phenyl‐4,5‐dihydrooxazole.     

Total Synthesis of (+)‐β‐Himachalene

An enantioselective synthesis of (+)‐β‐himachalene ( 2 ) was accomplished starting from (1S,2R)‐1,2‐epoxy‐p‐menth‐8‐ene ( 3 ) in 15 or 16 steps with an overall yield of ca. 6% (Schemes 3, 5, and 6). Key transformations include an Ireland–Claisen rearrangement, a Corey oxidative cyclization, and a ring expansion.     

Sol-Gel processing of silica nanoparticles and their applications

Recently, silica nanoparticles (SNPs) have drawn widespread attention due to their applications in many emerging areas because of their tailorable morphology. During the last decade, remarkable efforts have been made on the investigations for novel processing methodologies to prepare SNPs, resulting in better control of the size, shape, porosity and significant improvements in the physio-chemical properties. A number of techniques available for preparing SNPs namely, flame spray pyrolysis, chemical vapour deposition, micro-emulsion, ball milling, sol-gel etc. have resulted, a number of publications. Among these, preparation by sol-gel has been the focus of research as the synthesis is straightforward, scalable and controllable. Therefore, this review focuses on the recent progress in the field of synthesis of SNPs exhibiting ordered mesoporous structure, their distribution pattern, morphological attributes and applications. The mesoporous silica nanoparticles (MSNPs) with good dispersion, varying morphology, narrow size distribution and homogeneous porous structure have been successfully prepared using organic and inorganic templates. The soft template assisted synthesis using surfactants for obtaining desirable shapes, pores, morphology and mechanisms proposed has been reviewed. Apart from single template, double and mixed surfactants, electrolytes, polymers etc. as templates have also been intensively discussed. The influence of reaction conditions such as temperature, pH, concentration of reagents, drying techniques, solvents, precursor, aging time etc. have also been deliberated. These MSNPs are suitable for a variety of applications viz., in the drug delivery systems, high performance liquid chromatography (HPLC), biosensors, cosmetics as well as construction materials. The applications of these SNPs have also been briefly summarized.     

Phase Behavior of Diglycerol Monomyristate in Different Nonpolar Organic Solvent Systems

We have investigated the phase behavior of diglycerol monomyristate (DGM) in a variety of organic solvents over a wide range of temperatures and compositions. At lower temperature, there exists a surfactant solid, which solubilize different amounts of oils depending on the oil nature. The melting temperature of the solid phase is virtually constant in a wide range of composition. In all the systems, a lamellar liquid crystal (L_α) is formed in surfactant‐rich regions at intermediate temperatures between the solid‐melt and isotropic two‐ or single‐phase regions. In the dilute regions reverse vesicles are formed in the L_α+O regions mainly in the case of linear hydrocarbon type oils. In the aromatic and cyclic aliphatic oils, there are isotropic solutions at 25°C. However, there is dispersion of α‐solid in the case of liner hydrocarbon oils. Two liquid‐phase regions above the L_α phase are observed in the case of tetradecane and hexadecane. In the shorter chain oil systems, such as octane and decane, no two liquid‐phase appear above L_α region. That is the two liquid‐phase region is largely dependent on the chain length of the oils, and becomes wider in longer hydrocarbon oil.     

After‐Rinsing Hair Growth Promotions of Hinokitiol‐Containing Vesicles and Emulsions

Two kinds of topical dosage forms of hinokitiol (HKL), namely vesicles and oil‐in‐water (O/W) emulsions, were prepared. Behenyl trimethylammonium chloride (BTMAC) and fatty acids were used as bilayer‐forming materials of the vesicles, and oils were employed as oil phases of the emulsions. The substantivity of HKL in the preparations was evaluated in vitro using hairless mouse skins. After applying the preparations onto the skin and rinsing it, the amount of HKL left on the skin was determined using high performance liquid chromatography (HPLC). It was higher when HKL was encapsulated in cationic vesicles rather than in nonionic vehicles, emulsions. An ionic interaction between the cationic vehicle and negatively charged skin is likely to account for the high substantivity. Among the emulsion preparations, an emulsion having octyl salicylate as oil phase exhibited the highest substantivity of HKL. This is probably because that the oil is a good solvent for HKL and it is skin‐retentive. In vivo hair growth‐promotion effect of each dosage form was investigated, where the sample application onto the clipped backs of female mice (C57BL6) and the subsequent rinsing of the backs were done once a day for 30 days. Only HKL in the cationic vesicles had hair growth promotion effect, possibly due to the significant substantivity.     

Mechanical properties of hybrid glass/sugar palm fibre reinforced unsaturated polyester composites

A research has been carried out to investigate the mechanical properties of composites made by hybridizing sugar palm fibre (Arenga pinnata) with glass fibre into an unsaturated polyester matrix. Hybrid composites of glass/sugar palm fibre were fabricated in different weight ratios of strand mat glass fibres: sugar palm fibres 4:0, 4:1, 4:2, 4:3, 4:4, and 0:4. The hybrid effects of glass and sugar palm fibre on tensile, flexural and impact properties of the composites were evaluated according to ASTM D5083, ASTM D790 and ASTM D256 respectively. Results have been established that properties of hybrid glass/sugar palm composites such as tensile strength, tensile modulus, elongation at break, toughness, flexural strength, flexural modulus and impact strength are a function of fibre content. The failure mechanism and the adhesion between fibres/matrix were studied by observing the scanning electron micrographs of impact fracture samples. In general, the incorporation of both fibres into unsaturated polyester matrix shows a regular trend of increase in the mechanical properties.     

An Update of Nucleic Acids Aptamers Theranostic Integration with CRISPR/Cas Technology

The clustered regularly interspaced short palindromic repeat (CRISPR)/Cas system is best known for its role in genomic editing. It has also demonstrated great potential in nucleic acid biosensing. However, the specificity limitation in CRISPR/Cas has created a hurdle for its advancement. More recently, nucleic acid aptamers known for their high affinity and specificity properties for their targets have been integrated into CRISPR/Cas systems. This review article gives a brief overview of the aptamer and CRISPR/Cas technology and provides an updated summary and discussion on how the two distinctive nucleic acid technologies are being integrated into modern diagnostic and therapeutic applications     

Random coil phosphorus chemical shift of deoxyribonucleic acids

Random coil phosphorus chemical shift has been studied using 16 17-nucleotide DNA sequences. Due to the presence of residual base stacking in these sequences, the temperature and sequence effects were investigated at 50 and 55 degrees C. The phosphorus chemical shifts of random coil DNA sequences have been found to be independent of temperature. Sequence effect analysis shows that the phosphorus chemical shift of a nucleotide in a random coil DNA sequence depends on both its 5'- and 3'-nearest neighbors. A trimer model has been used to establish the random coil 31P chemical shift prediction protocol which shows an accuracy of 0.02 ppm.