Griffithmacleod1542

The discussions are focused on small-molecule and nanomaterials-based NIR probes.We report the first preparation of the s-cis,s-cis conformer of dihydroxycarbene (1cc) by means of pyrolysis of oxalic acid, isolation of the lower-energy s-trans,s-trans (1tt) and s-cis,s-trans (1ct) product conformers at cryogenic temperatures in a N2 matrix, and subsequent narrow-band near-infrared (NIR) laser excitation to give 1cc. Carbene 1cc converts quickly to 1ct via quantum-mechanical tunneling with an effective half-life of 22 min at 3 K. The potential energy surface features around 1 were pinpointed by convergent focal point analysis targeting the AE-CCSDT(Q)/CBS level of electronic structure theory. Computations of the tunneling kinetics confirm the time scale of the 1cc → 1ct rotamerization and suggest that direct 1cc → H2 + CO2 decomposition may also be a minor pathway. The intriguing latter possibility cannot be confirmed spectroscopically, but hints of it may be present in the measured kinetic profiles.This study shows that phosphorus sources can be recycled using the appropriate fluorous phosphine in the Wittig reaction. The designed fluorous phosphine, which has an ethylene spacer between its phosphorus atom and the perfluoroalkyl group, was synthesized from air-stable phosphine reagents. The synthesized phosphine can be used for the Wittig reaction process to obtain various alkenes in adequate yields and stereoselectivity. The concomitantly formed fluorous phosphine oxide was extracted from the reaction mixture using a fluorous biphasic system. The fluorous phosphine was regenerated by reducing the fluorous phosphine oxide with diisobutylaluminum hydride. Finally, a series of gram scale phosphorus recycling processes were performed, which included the Wittig reaction, separation, reduction, and reuse.Modulating the active sites of oxygen vacancies (OVs) to enhance the catalytic properties of nanomaterials has attracted much research interest in various fields, but its intrinsic catalytic mechanism is always neglected. Herein, we establish an efficient strategy to promote the electrochemical detection of Pb(II) by regulating the concentration of OVs in α-MoO3 nanorods via doping Ce3+/Ce4+ ions. #link# α-MoO3 with the Ce-doped content of 9% (C9M) exhibited the highest detection sensitivity of 106.64 μM μA-1 for Pb(II), which is higher than that achieved by other metal oxides and most precious metal nanomaterials. It is found that C9M possessed the highest concentration of OVs, which trapped some electrons for strong affinity interaction with Pb(II) and provided numerous atomic level interfaces of high surface free energy for catalysis reactions. X-ray absorption fine structure spectra and density functional theory calculation indicate that Pb(II) was bonded with the surface-activated oxygen atoms (Os) around Ce ions and obtained some electrons from Os. Besides, the longer Pb-O bonds on C9M were easier to break, causing a low desorption energy barrier to effectively accelerate Pb(II) desorbing to the electrode surface. This study helps to understand the changes in electronic structure and catalytic performance with heteroatom doping and OVs in chemically inert oxides and provide a reference for designing high-active electrocatalytic interfaces to realize ultrasensitive analysis of environmental contaminants.The self-assembly of gold nanoparticles (Au NPs) on a liquid phase interface is often employed as a surface-enhanced Raman scattering (SERS) platform with advantages of simple preparation, high reproducibility, and a defect-free character, but they are limited to only detect a target with Raman signals. To overcome this problem, microRNA 155 without a Raman signal can be detected by a liquid phase interfacial ratiometric SERS platform. Compared with the typical solid phase SERS platform, we propose a distinctive strategy not only owning the advantages of the liquid phase interfacial platform but also breaking the limitation of recent liquid-liquid interfacial SERS analysis. This platform presents a fabulous sensitivity with a limit of detection (LOD) of 1.10 aM for microRNA 155. By simply altering the duplex-specific nuclease (DSN) enzyme amplification, our strategy can realize detection of a variety of microRNAs, paving the way to practical applications of a liquid phase SERS platform.Bacterial tRNA-guanine transglycosylase (Tgt) is involved in the biosynthesis of the modified tRNA nucleoside queuosine present in the anticodon wobble position of tRNAs specific for aspartate, asparagine, histidine, and tyrosine. Inactivation of the tgt gene leads to decreased pathogenicity of Shigella bacteria. Therefore, Tgt constitutes a putative target for Shigellosis drug therapy. Since it is only active as homodimer, interference with dimer-interface formation may, in addition to active-site inhibition, provide further means to disable this protein. link2 A cluster of four aromatic residues seems important to stabilize the homodimer. We mutated residues of this aromatic cluster and analyzed each mutated variant with respect to the dimer and thermal stability or enzyme activity by applying native mass spectrometry, a thermal shift assay, enzyme kinetics, and X-ray crystallography. Our structural studies indicate a strong influence of pH on the homodimer stability. Apparently, Luminespib HSP (HSP90) inhibitor of a histidine within the aromatic cluster supports the collapse of an essential structural motif within the dimer interface at slightly acidic pH.Assembly of amphiphiles at the interface of two immiscible fluids is of great scientific and technological interest in offering efficient routes to smart vehicles for functional deliveries. Natural Quillaja saponin (QS) has gathered widespread interest within the scientific community as a result of its unique interfacial properties. link3 Herein, spontaneously interface-driven self-assembly (SIDSA) of QS at the oil-water interface was systematically studied by morphology and spectroscopy. It was found to self-assemble into a micrometer-scale network in helical fibers by combined intermolecular π-π stacking and hydrogen bonding among saponins at the liquid-liquid interface. From SIDSA, multilayer films on the surfaces of dispersed droplets were formed and enhanced emulsion stability. Interfacial QS-based films on droplet surfaces were also shown to confine interfacial diffusion processes by serving as transport barriers. Furthermore, they can be exploited to control the release of volatiles from the dispersed liquid phase by regulating the interface film, which is shown by molecular dynamics to occur through a hydrogen-bonded mechanism. These results provide new insight into the interfacial assembly structure that can enable unique controllable release in a broad range of applications in food, beverages, pharmaceuticals, and cosmetics.Bone defect repair at load-bearing sites is a challenging clinical problem for orthopedists. Defect reconstruction with implants is the most common treatment; however, it requires the implant to have good mechanical properties and the capacity to promote bone formation. In recent years, the piezoelectric effect, in which electrical activity can be generated due to mechanical deformation, of native bone, which promotes bone formation, has been increasingly valued. Therefore, implants with piezoelectric effects have also attracted great attention from orthopedists. In this study, we developed a bioactive composite scaffold consisting of BaTiO3, a piezoelectric ceramic material, coated on porous Ti6Al4V. This composite scaffold showed not only appropriate mechanical properties, sufficient bone and blood vessel ingrowth space, and a suitable material surface topography but also a reconstructed electromagnetic microenvironment. The osteoconductive and osteoinductive properties of the scaffold were reflected by thepromising composite biomaterial for repairing bone defects, especially at load-bearing sites, that may have great clinical translation potential.Ethyl lactate is an important flavor substance in baijiu, and it is also one of the common raw materials in the production of flavors and spices. In this study, we first established the ethyl lactate biosynthesis pathway in Saccharomyces cerevisiae α(L) by introducing propionyl coenzyme A transferase (Pct) and alcohol acyltransferase (AAT), and the results showed that strain α(L)-CP-Ae produced the most ethyl lactate 239.53 ± 5.45 mg/L. Subsequently, the copy number of the Pct cp gene and AeAT9 gene was increased, and the modified strain α(L)-tCP-tAe produced 346.39 ± 3.99 mg/L ethyl lactate. Finally, the porin gene (por 2 ) and the mitochondrial pyruvate carrier gene (MPC2) were knocked to impede mitochondrial transport of pyruvate, and the final modified strain α(L)-tCP-tAeΔpor2 produced ethyl lactate 420.48 ± 6.03 mg/L.A solar thermoelectric generator (STEG) that generates electricity from sunlight is expected to be a promising technology for harvesting and conversion of clean solar energy. The integration of a phase-change material (PCM) with the STEG even more enables engines to durably generate power in spite of solar radiation flux. However, its photothermal conversion and output electricity is still limited ( less then 15 W/m2) by the PCM's deficient thermal management performance, i.e., restricted thermal conductivity and nonuniform heat-transfer behavior under concentrated sunlight radiation. In this study, a biomimetic phase-change composite, with centrosymmetric and a multidirectionally aligned boron nitride network embedded in polyethylene glycol, is tailored for the STEG via a radial ice-template assembly and infiltration strategy, which behaves in a highly and multidirectionally thermoconductive way and enables a rapid transfer of heat flux and uniform temperature distribution with respect to even a spot-like heat source. As a consequence, a powerful STEG is tactfully designed via the integration of this high-thermal-management characteristic and maximum collection of solar beams, for durable and real-environment solar-thermal-electric conversion, with its photothermal energy conversion efficiency of up to 85.1% and a high peak power density of 40.28 W/m2.In this study, we successfully purified a novel lactose-oxidizing enzyme in Pseudomonas taetrolens for the first time. The purified enzyme was identified as malatequinone oxidoreductase (MQO, EC 1.1.5.4), which showed the malate-oxidizing activity converting malate into oxaloacetate. We characterized the enzymatic properties of this interesting MQO from P. taetrolens, such as the substrate specificity toward various saccharides and the effects of temperature, pH, and metal ions on the activity and stability of MQO. MQO exhibited unique substrate specificity, as it only oxidized disaccharides with reducing-end glucosyl residues, such as lactose, but not monosaccharides. Using the high oxidizing activity of MQO toward lactose, we successfully produced lactobionic acid (LBA), a valuable organic acid used in the cosmetic, food, and pharmaceutical industries, from lactose in Escherichia coli in which the quinoprotein glucose dehydrogenase gene was inactivated, the LBA nonproducing strain, by heterologously expressing MQO with pyrroloquinoline quinone.