One-step synthesis of sequence-controlled multiblock polymers with up to 11 segments from monomer mixture

Switchable polymerization holds considerable potential for the synthesis of highly sequence-controlled multiblock. To date, this method has been limited to three-component systems, which enables the straightforward synthesis of multiblock polymers with less than five blocks. Herein, we report a self-switchable polymerization enabled by simple alkali metal carboxylate catalysts that directly polymerize six-component mixtures into multiblock polymers consisting of up to 11 blocks. Without an external trigger, the catalyst polymerization spontaneously connects five catalytic cycles in an orderly manner, involving four anhydride/epoxide ring-opening copolymerizations and one L-lactide ring-opening polymerization, creating a one-step synthetic pathway. Following this autotandem catalysis, reasonable combinations of different catalytic cycles allow the direct preparation of diverse, sequence-controlled, multiblock copolymers even containing various hyperbranched architectures. This method shows considerable promise in the synthesis of sequentially and architecturally complex polymers, with high monomer sequence control that provides the potential for designing materials.

Utilization of Andong Leaf Extract (Cordyline fruticosa) as an Alternative for Coloring the Eggs of Intestinal Nematode

Microscopic examination is essential to find the type of worm that causes infection. Direct examination of worm eggs needs to use staining to distinguish between worm eggs and food residues that are not completely digested. The dyes commonly used are synthetic. The purpose of this study was to replace synthetic dyes with natural dyes with Andong (Cordyline Fruticosa) leaf juice. It can be used as an alternative or a substitute for dyes. This research method is descriptive, conducted at the Parasitology Laboratory of Poltekkes Kemenkes Pontianak. The population in this study was the juice of the leaves of Andong (Cordyline Fruticosa). The method of inspection is direct preparation with an object glass as is routinely done, but the dye is replaced with Andong leaf juice (Cordyline Fruticosa). The results showed that natural dye Andong leaf juice (Cordyline Fruticosa), gave a clear color to the absorption of intestinal nematode worm eggs as the test target. This study concludes that the juice of the leaves of Andong (Cordyline Fruticosa) with alcohol solvent can be used as an alternative dye for the examination of intestinal nematode worm eggs.

Copper-Catalyzed Ring-Opening Reactions of Alkyl Aziridines with B2pin2: Experimental and Computational Studies

The possibility to form new C–B bonds with aziridines using diboron derivatives continues to be a particularly challenging field in view of the direct preparation of functionalized β-aminoboronates, which are important compounds in drug discovery, being a bioisostere of β-aminoacids. We now report experimental and computational data that allows the individuation of the structural requisites and of reaction conditions necessary to open alkyl aziridines using bis(pinacolate)diboron (B2pin2) in a regioselective nucleophilic addition reaction under copper catalysis.

Direct Fabrication of CsPbxMn1−x(Br,Cl)3 Thin Film by a Facile Solution Spraying Approach

Nowadays, Mn-doping is considered as a promising dissolution for the heavy usage of toxic lead in CsPbX3 perovskite material. Interestingly, Mn-doping also introduces an additional photoluminescence band, which is favorable to enrich the emission gamut of this cesium lead halide. Here, a solution spraying strategy was employed for the direct preparation of CsPbxMn1−x(Br,Cl)3 film through MnCl2 doping in host CsPbBr3 material. The possible fabrication mechanism of the provided approach and the dependences of material properties on Mn-doping were investigated in detail. As the results shown, Pb was partially substituted by Mn as expected. With the ratio of PbBr2:MnCl2 increasing from 3:0 to 1:1, the obtained film separately featured green, cyan, orange-red and pink-red emission, which was caused by the energy transferring process. Moreover, the combining energy of Cs, Pb, and Mn gradually red-shifted resulted from the formation of Cs-Cl, Pb-Cl and Mn-Br coordination bonding as MnCl2 doping increased. In addition, the weight of short decay lifetime of prepared samples increased with the doping rising, which indicated a better exciton emission and less defect-related transition. The aiming of current work is to provide a new possibility for the facile preparation of Mn-doping CsPbX3 film material.

Toward scalable biocatalytic conversion of 5-hydroxymethylfurfural by galactose oxidase using coordinated reaction and enzyme engineering

Abstract5-Hydroxymethylfurfural (HMF) has emerged as a crucial bio-based chemical building block in the drive towards developing materials from renewable resources, due to its direct preparation from sugars and its readily diversifiable scaffold. A key obstacle in transitioning to bio-based plastic production lies in meeting the necessary industrial production efficiency, particularly in the cost-effective conversion of HMF to valuable intermediates. Toward addressing the challenge of developing scalable technology for oxidizing crude HMF to more valuable chemicals, here we report coordinated reaction and enzyme engineering to provide a galactose oxidase (GOase) variant with remarkably high activity toward HMF, improved O2 binding and excellent productivity (>1,000,000 TTN). The biocatalyst and reaction conditions presented here for GOase catalysed selective oxidation of HMF to 2,5-diformylfuran offers a productive blueprint for further development, giving hope for the creation of a biocatalytic route to scalable production of furan-based chemical building blocks from sustainable feedstocks.

Comparison of the Values of a Novel Exolytic and Two Endolytic Alginate Lyases with Mannuronate Preference for Direct Preparation of Oligosaccharides, Action Modes, and Underlying Catalytic Mechanisms

Recent exploration of tool-like alginate lyases has focused on their oligosaccharide products and corresponding substrate action modes, and most were characterized as endolytic lyases with guluronate (G) preference. Herein, we elucidated a novel exolytic lyase, Aly-6, and two typical endolytic lyases, AlgL-Pae and AlgL-Avi, all with mannuronate (M) preferences. AlgL and heparinase_II_III modules play essential roles in determining the similar characteristics of these enzymes, although they are quite different in sequence characteristics. Aly-6 degraded substrates completely by continuously cleaving various monosaccharide units from nonreducing ends and producing various size-defined ΔG-terminated oligosaccharide fractions as intermediate alginate digests, which was inhibited by fluorescent labeling of reducing ends. Distinctly, AlgL-Pae and AlgL-Avi varied their action modes toward associated alginate substrates and therefore eventually degraded alginate into various size-defined oligosaccharide products with a specific structure-based succession rule. This study provided new insights into the action modes, associated mechanisms, and enzyme applications of M-preferred lyases.

Micro-patterned deposition of MoS2 ultrathin-films by a controlled droplet dragging approach

Micropatterning of transition metal dichalcogenide (TMDC) ultrathin-films and monolayers has been demonstrated by various multi-step approaches. However, directly achieving a patterned growth of TMDC films is still considered to be challenging. Here, we report a solution-based approach for the synthesis of patterned MoS2 layers by dragging a precursor solution droplet with variable velocities across a substrate. Utilizing the pronounced shearing velocity dependence in a Landau-Levich deposition regime, MoS2 films with a spatially modulated thickness with alternating mono/bi- and few-layer regions are obtained after precursor annealing. Generally, the presented facile methodology allows for the direct preparation of micro-structured functional materials, extendable to other TMDC materials and even van der Waals heterostructures.