A Singular System with Precise Dosing and Spatiotemporal Control of CRISPR‐Cas9

Several genome engineering applications of CRISPR‐Cas9, an RNA‐guided DNA endonuclease, require precision control of Cas9 activity over dosage, timing, and targeted site in an organism. While some control of Cas9 activity over dose and time have been achieved using small molecules, and spatial control using light, no singular system with control over all the three attributes exists. Furthermore, the reported small‐molecule systems lack wide dynamic range, have background activity in the absence of the small‐molecule controller, and are not biologically inert, while the optogenetic systems require prolonged exposure to high‐intensity light. We previously reported a small‐molecule‐controlled Cas9 system with some dosage and temporal control. By photocaging this Cas9 activator to render it biologically inert and photoactivatable, and employing next‐generation protein engineering approaches, we have built a system with a wide dynamic range, low background, and fast photoactivation using a low‐intensity light while rendering the small‐molecule activator biologically inert. We anticipate these precision controls will propel the development of practical applications of Cas9.     

Regulating Nonclassical Pathways of Silicalite‐1 Crystallization through Controlled Evolution of Amorphous Precursors

Differentiating mechanisms of zeolite crystallization is challenging owing to the vast number of species in growth solutions. The presence of amorphous colloidal particles is ubiquitous in many zeolite syntheses, and has led to extensive efforts to understand the driving force(s) for their self‐assembly and putative roles in processes of nucleation and growth. In this study, we use a combination of in situ scanning probe microscopy, particle dissolution measurements, and colloidal stability assays to elucidate the degree to which silica nanoparticles evolve in their structure during the early stages of silicalite‐1 synthesis. We show how changes in precursor structure are mediated by the presence of organics, and demonstrate how these changes lead to significant differences in precursor–crystal interactions that alter preferred modes of crystal growth. Our findings provide guidelines for selectively controlling silicalite‐1 growth by particle attachment or monomer addition, thus allowing for the manipulation of anisotropic rates of crystallization. In doing so, we also address a longstanding question regarding what factors are at our disposal to switch from a nonclassical to classical mechanism.     

Photocured characteristics of fast photocurable acrylic formulations and investigations by differential photo calorimeter

Nanofluids are obtained by suspending metallic or non-metallic nanoparticles in conventional base liquids and can be employed to increase heat transfer rate in various applications. In this study, the effects of adding three types of nanofluids on turbulent convective heat transfer at the entrance region of a constant wall heat flux tube were experimentally studied. The nanofluids were mixtures of aluminium oxide, copper oxide, and silicon carbide at various nanoparticle volume fractions ranging from 0.0002 to 0.002 in water. The convective heat transfer coefficient was measured at different Reynolds numbers of 10,000–50,000. At these concentrations and Reynolds numbers, a maximum of 11–18% of convection heat transfer coefficient was observed as compared to the base fluid, showing a 6–9% increase on average. In this study, it was observed that changes in the nanoparticle type had no considerable effect on heat transfer coefficient increase. According to the model proposed here, the dimensionless thickness of laminar sub-layer is specified as a functional equation of the volume fraction of nanoparticles for each material.

     

In vitro and in silico interaction of faba bean (Vicia faba L.) seed extract with xanthine oxidase and evaluation of antioxidant activity as a therapeutic potential

Acetone extract of faba bean (Vicia faba L.) was found to be highest total phenol and flavonoid content among all extracts. Antioxidant activity for inhibition percentage (free radical scavenging activity) had 86.47% for acetone extract, and 97.36% for ascorbic acid respectively. IC₅₀ value of ascorbic acid and acetone extact were found to be 9 μg/mL ± 0.20 and 30 μg/mL ± 0.21. Faba bean seeds had catechin, epicatechin, gallic acid and ellagic acid which on molecular docking study revealed that it binds effectively with xanthine oxidase by binding energy of –7.78, –6.11, –6.39, –5.78 kcal/mol respectively compared to allopurinol drug having binding energy of –4.94 kcal/mol. Gallic acid, ellagic acid, catechin, epicatechin (polyphenols) and allopurinol bind other than catalytic residues (Glu-1261) of xanthine oxidase. In vitro and in silico analysis recommended that mode of enzyme inhibition was mixed type.     

Testing Lorentz invariance and CPT conservation with NuMI neutrinos in the MINOS near detector

A search for a sidereal modulation in the MINOS near detector neutrino data was performed. If present, this signature could be a consequence of Lorentz and CPT violation as predicted by the effective field theory called the standard-model extension. No evidence for a sidereal signal in the data set was found, implying that there is no significant change in neutrino propagation that depends on the direction of the neutrino beam in a sun-centered inertial frame. Upper limits on the magnitudes of the Lorentz and CPT violating terms in the standard-model extension lie between 10(-4) and 10(-2) of the maximum expected, assuming a suppression of these signatures by a factor of 10(-17).     

Three‐dimensional structure of cyclic antibiotic teicoplanin aglycone using NMR distance and dihedral angle restraints in a DMSO solvation model

The three‐dimensional solution conformation of teicoplanin aglycone was determined using NMR spectroscopy. A combination of NOE and dihedral angle restraints in a DMSO solvation model was used to calculate an ensemble of structures having a root mean square deviation of 0.17 Å. The structures were generated using systematic searches of conformational space for optimal satisfaction of distance and dihedral angle restraints. Comparison of the NMR‐derived structure of teicoplanin aglycone with the X‐ray structure of a teicoplanin aglycone analog revealed a common backbone conformation with deviation of two aromatic side chain substituents. Experimentally determined backbone ¹³C chemical shifts showed good agreement with those computed at the density functional level of theory, providing a cross validation of the backbone conformation. The flexible portion of the molecule was consistent with the region that changes conformation to accommodate protein binding. The results showed that a hydrogen‐bonded DMSO molecule in combination with NMR‐derived restraints together enabled calculation of structures that satisfied experimental data. Copyright © 2015 John Wiley & Sons, Ltd.     

Fluoride‐Catalyzed Deblocking: A Route to Polymeric Urethanes

We report a fluoride‐catalyzed deblocking of urethanes as “blocked” isocyanates. Organic and inorganic sources of fluoride ion proved effective for deblocking urethanes and for converting polyurethanes to small molecules. Distinct from conventional deblocking chemistry involving organometallic compounds and high temperatures, the method we describe is metal‐free and operates at or slightly above room temperature. The use of fluorescent blocking agents enabled visual and spectroscopic monitoring of blocking/deblocking reactions, and the selected conditions proved applicable to urethanes containing a variety of blocking groups. The method additionally enabled a one pot deblocking and polymerization with α,ω‐diols. Overall, this deblocking/polymerization strategy offers a convenient and efficient solution to problems that have limited the breadth of applications of polyurethane chemistry.     

Gold(I)-Catalyzed and PTSA-Promoted Cycloisomerization of Ynamides to Access Pyrrole Substituted α,β-Unsaturated Ketones**

Substituted pyrroles are prevalent aromatic ring systems encountered in numerous natural products and bioactive molecules. Herein, a novel ynamide scaffold has been designed, synthesized and subsequently applied to an unprecedented gold-catalyzed and para-toluenesulfonic acid (PTSA)-assisted cascade cycloisomerization reaction for the synthesis of β-pyrrole substituted α,β-unsaturated ketones. Notably, the reaction is stereoselective, offering E-isomer as major product with low to moderate yield.