Gomal university D.I.Khan

Gomal university D.I.Khan ........

The world of Modern Physics has lost a huge asset. What a loss for Pakistan and Physics.This nation will never forget yo...
10/10/2021

The world of Modern Physics has lost a huge asset.
What a loss for Pakistan and Physics.
This nation will never forget you Sir!
Thank you Sir for everything.
Rest in peace

Check out this communication from titled "Lewis-Acid-Catalyzed (3+2)-Cycloadditions of Donor-Acceptor Cyclopropanes wit...
17/09/2021

Check out this communication from titled "Lewis-Acid-Catalyzed (3+2)-Cycloadditions of Donor-Acceptor Cyclopropanes with Thioketenes."

Read it here: https://t.co/BX9h8OdjxG


by Grzegorz Mloston, , and co-workers () https://t.co/zwlCcAQmXI

The cage molecule, which was first synthesised in 2004, is made up of 12 palladium ions and 24 bridging ligandshttps://t...
17/09/2021

The cage molecule, which was first synthesised in 2004, is made up of 12 palladium ions and 24 bridging ligands

https://t.co/1PzMzOtBz1

23/09/2019

Hybrid superhydrophilic–superhydrophobic micro/nanostructures fabricated by femtosecond laser-induced forward transfer for sub-femtomolar Raman detection!

Abstract
Raman spectroscopy plays a crucial role in biochemical analysis. Recently, superhydrophobic surface-enhanced Raman scattering (SERS) substrates have enhanced detection limits by concentrating target molecules into small areas. However, due to the wet transition phenomenon, further reduction of the droplet contact area is prevented, and the detection limit is restricted. This paper proposes a simple method involving femtosecond laser-induced forward transfer for preparing a hybrid superhydrophilic–superhydrophobic SERS (HS-SERS) substrate by introducing a superhydrophilic pattern to promote the target molecules to concentrate on it for ultratrace detection. Furthermore, the HS-SERS substrate is heated to promote a smaller concentrated area. The water v***r film formed by the contact of the solution with the substrate overcomes droplet collapse, and the target molecules are completely concentrated into the superhydrophilic region without loss during ev***ration. Finally, the concentrated region is successfully reduced, and the detection limit is enhanced. The HS-SERS substrate achieved a final contact area of 0.013 mm2, a 12.1-fold decrease from the unheated case. The reduction of the contact area led to a detection limit concentration as low as 10−16 M for a Rhodamine 6G solution. In addition, the HS-SERS substrate accurately controlled the size of the concentrated areas through the superhydrophilic pattern, which can be attributed to the favorable repeatability of the droplet concentration results. In addition, the preparation method is flexible and has the potential for fluid mixing, fluid transport, and biochemical sensors, etc.
Courtesy
Xiaodan Ma, Lan Jiang, […]Tianhong Cui
Microsystems & Nanoengineeringvolume 5, Article number: 48

Nitrogen-Based Lewis Acids Derived from Phosphonium Diazo Cations.
10/07/2018

Nitrogen-Based Lewis Acids Derived from Phosphonium Diazo Cations.

In Vitro Reconstitution of OxyC Activity Enables Total Chemoenzymatic Syntheses of Vancomycin Aglycone VariantsThe bioac...
13/06/2018

In Vitro Reconstitution of OxyC Activity Enables Total Chemoenzymatic Syntheses of Vancomycin Aglycone Variants

The bioactivity of vancomycin is enabled by three aromatic crosslinks, the biosynthesis of which has been an active area of investigation for two decades. Two cytochrome P450 enzymes, OxyB and OxyA, have been shown to introduce bisaryl ether linkages with the help of a so‐called X‐domain. The final crosslink, however, a biaryl bond thought to be installed by OxyC, has remained elusive. We report the in vitro reconstitution of the OxyC reaction and formation of the first carbon–carbon crosslink in any glycopeptide antibiotic. Using a cascade sequence, in which the peptide substrate was incubated with the Oxy enzymes in turn, we completed the chemoenzymatic synthesis of a vancomycin aglycone variant. This approach was also used to generate a new analogue carrying a thioamide linkage at residue 4, a precursor to the amidine derivative, which is effective against vancomycin‐resistant pathogens. Our results set the stage for creating therapeutic vancomycin derivatives by using the native metalloenzymes.

Biosynthesis and Heterologous Production of Vioprolides: Rational Biosynthetic Engineering and Unprecedented 4‐Methylaze...
13/06/2018

Biosynthesis and Heterologous Production of Vioprolides: Rational Biosynthetic Engineering and Unprecedented 4‐Methylazetidinecarboxylic Acid Formation

Vioprolides are a promising class of anticancer and antifungal lead compounds produced by the myxobacterium Cystobacter violaceus Cb vi35. Previously nothing had been reported about their biosynthesis, including the origin of the unusual 4‐methylazetidinecarboxylic acid (MAZ) moiety. We describe the vioprolide biosynthetic gene cluster and solve the production obstacle by expression in three heterologous hosts. Starting from unstable production in the wild type at the single‐digit mg L−1 scale, we developed a stable host that eventually allowed for yields of up to half a gram per liter in fermenters. Gene inactivations coupled with isotope feeding studies identified an S‐adenosylmethionine (SAM)‐dependent enzyme and a methyltransferase as being responsible for the generation of the MAZ building block by a proposed mechanism unprecedented in bacteria. Furthermore, nonnatural vioprolide derivatives were generated via rational genetic engineering.

The first persistent platinum(I)‐centered radical was generated by homolytic cleavage of a Pt−HgSiR3 bond of a mercury‐s...
07/06/2018

The first persistent platinum(I)‐centered radical was generated by homolytic cleavage of a Pt−HgSiR3 bond of a mercury‐substituted platinum(II) complex. The PtI radical was characterized by EPR spectroscopy, chemical trapping experiments, and density functional theory (DFT) calculations.

09/04/2018

Hybrid Aqueous Batteries Extend Electrode Life:

Rechargeable aqueous metal-ion batteries (RAMBs) are a safe, low-cost, and environmentally friendly battery technology. However, RAMBs suffer from capacity fading because of H2/O2 evolution reactions, proton co-intercalation of ions contained within the electrolyte, and dissolution of electrode materials in an aqueous setting. Hybrid aqueous batteries (HABs) containing selective cation channels could extend the lifetime of RAMB electrodes.

Mianqi Xue and Rui Li, Peking University, Shenzhen, China, and coworkers have designed a mixed potassium–sodium HAB containing a Prussian blue K2FeFe(CN)6 cathode (K-FeHCF) and a carbon-coated NaTi2(PO4)3 anode (NTP/C). The cathode and anode are selective for K+ and Na+ ions, respectively. Ultrafast ion conduction is possible with NTP/C.

A HAB battery containing the K-FeHCF and NTP/C electrodes delivers a 160 mAh g–1 capacity at 0.5 C. The researchers suggest that the battery’s 69.6 Wh kg–1 energy density is comparable to that of commercial mixed-ion aqueous batteries such as lead acid, Ni/Cd, and nickel—metal hydride batteries.

Courtacy:

Author: Angewandte Chemie International Edition
Published Date: 09 April 2018
Source / Publisher: Angewandte Chemie International Edition/Wiley-VCH

26/03/2018

Catalyst Surface Modification for Selective Styrene Oxidation:

The selective catalytic oxidation of styrene into styrene oxide and benzaldehyde has attracted widespread interest. Both compounds have applications in various fields such as agrochemicals and pharmaceuticals. However, it remains challenging to develop highly active and selective catalysts for the oxidation of styrene with O2 under mild conditions.

Ran Long, Yujie Xiong, University of Science and Technology of China, Hefei, and colleagues have developed a catalyst for the selective styrene oxidation based on surface lattice engineering. The team sparsely deposited Au atoms on the surface of Pd concave nanostructures (pictured). The activation degree of adsorbed O2 can be tuned by tailoring the concentration of Au atoms on the surface. This suppresses the formation of over-oxidized byproducts. Interestingly, the nanostructures could harvest light to drive the reactions through a plasmonic photothermal effect.

The designed catalyst achieves high product selectivity in the aerobic oxidation of styrene with ambient O2. This result provides insights into rationally designing catalysts for selective oxidation reactions with molecular oxygen under mild conditions.

Courtacy and,
Source / Publisher: ChemNanoMat/Wiley-VCH

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