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Nitrilases are promising biocatalysts to produce high-value-added carboxylic acids through hydrolysis of nitriles. However, since the enzymes always show low activity and sometimes with poor reaction specificity toward 2-chloronicotinonitrile (2-CN), very few robust nitrilases have been reported for efficient production of 2-chloronicotinic acid (2-CA) from 2-CN. Herein, a nitrilase from Paraburkholderia graminis (PgNIT) was engineered to improve its catalytic properties. We identified the beneficial residues via computational analysis and constructed the mutant library. The positive mutants were obtained and the activity of the "best" mutant F164G/I130L/N167Y/A55S/Q260C/T133I/R199Q toward 2-CN was increased from 0.14 × 10

The development of efficient synthetic methods for accessing enantioenriched α-chiral amines is of great importance in the disciplines of medicinal and synthetic organic chemistry. Enantioselective Rh-catalyzed 1,2-addition reactions to activated imine derivatives are regarded as useful protocols for forming α-chiral amines. This personal account outlines our efforts to develop chiral bicyclo[2.2.1]heptadiene ligands for Rh-catalyzed asymmetric additions of various organoboron reagents to a wide range of imine derivatives. Transformations of the thus-obtained adducts into known natural products or molecules of pharmaceutical importance serve to confirm their synthetic usefulness.

Activation of the cyclic GMP-AMP synthase-stimulator of the interferon gene (cGAS-STING) pathway is a potent anticancer immunotherapeutic strategy, and the induction of pyroptosis is a feasible way to stimulate the anticancer immune responses. Herein, two Pt

Taxifolin is known to have multiple biological functions. It has been widely used as a multifunctional food additive, and consequently, the global demand for taxifolin is increasing. The main method for taxifolin production is an extraction from larch wood, but the global resources of larch are limited. Astilbin, taxifolin-3-o-rhamnoside, is abundant in many plants and much more readily available, meaning taxifolin can be obtained by deglycosylation of astilbin. In this study, a fungal strain, Aspergillus fumigatus SQH4, was isolated from an enrichment culture of Smilax glabra rhizome to achieve the deglycosylation reaction. A culture of SQH4, adjusted to pH 6.5, with 5 g/L astilbin achieved a yield of taxifolin of 91.3% after biotransformation for 14 h at 35 °C. These findings offer an alternative method for the production of taxifolin.

Carbon monoxide (CO) plays an important role in signaling in cells, making its use as a therapeutic tool highly intriguing. Reduced burst emissions are important to avoid the cytotoxicity and tissue damage caused by CO. Here, we developed a stable diiron carbonyl [FeFe] hydrogenase agent that enables prolonged CO release activity (half-life of over 9 h) in cells. The integrated analysis allowed the identification of the key intermediate sites and CO accumulations with subcellular resolution. We observed that the [FeFe]

Single-atom catalysts (SACs) featuring the complete atomic utilization of metal, high-efficient catalytic activity, superior selectivity, and excellent stability have been emerged as a frontier in the catalytic field. Recently, increasing interests have been drawn to apply SACs in biomedical fields for enzyme-mimic catalysis and disease therapy. To fulfill the demand of precision and personalized medicine, precisely engineering the structure and active site toward atomic levels is a trend for nanomedicines, promoting the evolution of metal-based biomedical nanomaterials, particularly biocatalytic nanomaterials, from nanoparticles to clusters and now to SACs. This review outlines the syntheses, characterizations, and catalytic mechanisms of metal clusters and SACs, with a focus on their biomedical applications including biosensing, antibacterial therapy, and cancer therapy, as well as an emphasis on their in vivo biological safeties. Challenges and future perspectives are ultimately prospected for SACs in diverse biomedical applications.

Ferroptosis is a programmed cell death pathway discovered in recent years, and ferroptosis-inducing agents have great potential as new antitumor candidates. Here, we report a Ir

2D extended organic cocrystals were constructed using 1,4-diiodotetrafluorobenzene and aromatic aldehydes via IOaldehyde halogen bonds on an Au(111) surface. The competition and synergy of halogen bonds and hydrogen bonds in 2D co-crystallization were revealed by scanning tunneling microscopy.

Dehydration of (S,S)-1,2-bis(1H-benzo[d]imidazol-2-yl)ethane-1,2-diol (H4 L) to (Z)-1,2-bis(1H-benzo[d]imidazol-2-yl)ethenol) (H3 L') was found to be metal-assisted, occurs under solvothermal conditions (H2 O/CH3 OH), and leads to [MnII4 (H3 L)4 Cl2 ]Cl2 ⋅5 H2 O⋅5 CH3 OH (Mn4 L4 ) and [MnII4 (H2 L')6 (μ3 -OH)]Cl⋅4 CH3 OH⋅H2 O (Mn4 L'6 ), respectively. Their structures were determined by single-crystal XRD. Extensive ESI-MS studies on solutions and solids of the reaction led to the proposal consisting of an initial stepwise assembly of Mn4 L4 from the reactants via [MnL] and [Mn2 L2 ] below 80 °C, and then disassembly to [MnL] and [MnL2 ] followed by ligand modification before reassembly to Mn4 L'6 via [MnL'], [MnL'2 ], and [Mn2 L'3 ] with increasing solvothermal temperature up to 140 °C. Identification of intermediates [Mn4 Lx L'6-x ] (x=5, 4, 3, 2, 1) in the process further suggested an assembly/disassembly/in situ reaction/reassembly transformation mechanism. These results not only reveal that multiple phase transformations are possible even though they were not realized in the crystalline state, but also help to better understand the complex transformation process between coordination clusters during "black-box" reactions.

Methane is one of the most abundant molecules on Earth. Most of the state-of-the-art methane chemical conversion technologies require high temperatures, they are accompanied by insufficient selectivity, carbon deposition and major production of carbon dioxide. Development of the methane conversion technologies at mild conditions is important for the rational utilization of renewable and fossil feedstocks and for the environment. The goal of this review is to perform a comparative analysis of low temperature methane photocatalytic conversion routes such as methane oxidation, methane reforming and methane coupling. Methane photocatalytic reforming and selective oxidation currently exhibit the highest conversion rates, while methane coupling shows the highest selectivity. The most promising routes could be methane oxidation to methanol, which simultaneously exhibits higher productivity and selectivity. Further improvements in the methane conversion can be achieved by the design of new materials, photoreactors and operating modes, such as photochemical looping and combining photocatalysis with electrocatalysis.

The photocatalytic performance of Ag3PO4 is severely restricted by the photocorrosion and high charge carrier recombination rate. In order to overcome these defects, a novel Ag3PO4/calcined Zn-Al layered double hydroxides (APMO) heterostructure photocatalyst was fabricated via in-situ growth of Ag3PO4 particles on the surface of calcined Zn-Al layered double hydroxides (MMO). The crystal structures, morphologies, optical and photoelectrochemical properties of the as-synthesized samples were characterized using various techniques, and its photocatalytic activity for tetracycline (TC) degradation was evaluated under simulated solar light irradiation. Obviously, all the APMO composites demonstrated much higher photocatalytic performances for TC degradation than pure Ag3PO4. Especially, the APMO70 showed the highest photocatalytic activity, which was almost about 49.3 times as high as that of pure Ag3PO4, and the degradation efficiency was still above 89% after 5 cycles. The improved photocatalytic performance and stability of APMO were ascribed to the efficient charge transfer and strong interfacial contact between Ag3PO4 and MMO. The possible photocatalytic mechanisms involving the charge transfer pathway and reactive species generation during the process of TC degradation were also discussed. Finally, the aquatic toxicity of TC was assessed using Chlorella vulgaris (C. vulgaris) as an ecological indicator, and the result suggested that the as-prepared APMO composite can effectively diminish the aquatic toxicity of TC.

International audience; Fischer-Tropsch synthesis (FTS) is an essential approach to convert coal, biomass, and shale gas into fuels and chemicals, such as lower olefins, gasoline, diesel, and so on. In recent years, there has been increasing motivation to deploy FTS at commercial scales which has been boosting the discovery of high performance catalysts. In particular, the importance of support in modulating the activity of metals has been recognized and carbonaceous materials have attracted attention as supports for FTS. In this review, we summarised the substantial progress in the preparation of carbon-based catalysts for FTS by applying activated carbon (AC), carbon nanotubes (CNTs), carbon nanofibers (CNFs), carbon spheres (CSs), and metal-organic frameworks (MOFs) derived carbonaceous materials as supports. A general assessment of carbon-based catalysts for FTS, concerning the support and metal properties, activity and products selectivity, and their interactions is systematically discussed. Finally, current challenges and future trends in the development of carbon-based catalysts for commercial utilization in FTS are proposed.

Ultraviolet (UV) radiation from sunlight has various adverse effects, thus, UV blockage is recommended for preventing sunburn. Common sunscreen ingredients, such as nanosized titanium dioxide and zinc oxide, offer effective protection and enhance cosmetic appearance, however, health concerns have been raised regarding their photocatalytic activity, which generates reactive oxygen species under UV illumination. Silver nanoparticles (AgNPs) are known as safe materials for use in a wide spectrum of biomedical applications. In vitro studies have revealed that AgNPs may have a protective effect against UV irradiation, but the effects in animal studies remain unclear. The present study demonstrated that AgNPs effectively protect against UVB-induced skin damage both in cell cultures and mouse models. These results suggested that AgNPs are feasible and safe as sunscreen ingredients for protection against UVB-induced skin damage.

Bacillus licheniformis γ-glutamyltranspeptidase (BlGGT) belongs to N-terminal nucleophile hydrolase superfamily in which all inclusive members are synthetized as single-chain precursors, and then self-processed to form mature enzymes. Here we investigated the role of a conserved Asn450 residue in BlGGT through site-directed mutagenesis and molecular characterization of four relevant variants. Substitution of Asn450 by arginine resulted in a significant reduction in the catalytic activity of BlGGT. Conversely, N450A and N450D displayed an enhanced activity. The catalytic efficiency of BlGGT was calculated to be 16.04mM(-1)s(-1), but this value was either decreased to 8.93mM(-1)s(-1) in N450K or increased to more than 123.65mM(-1)s(-1) in N450A and N450D. In addition, the ratio of transpeptidation to hydrolysis was increased from 3.5 to more than 7.6 by the mutations. Structural analyses showed that fluorescence, circular dichroism spectra and thermal denaturation profiles of mutant proteins were essentially consistent with those of BlGGT. However, guanidine hydrochloride (GdnHCl)-induced transition was significantly reduced in comparison with the wild-type enzyme. Molecular modeling suggests that residue Asn450 of BlGGT is important to create suitable environments for both autoprocessing and catalytic reactions.

The photocatalytic performance of layered double hydroxides (LDH) is usually confined to the slow interface mobility and high recombination rate of photogenerated electron-hole pairs in material. To overcome the low photocatalytic efficiency, novel Ag

Six mutants bearing single amino acid substitutions in the small subunit of Bacillus licheniformis γ-glutamyltranspeptudase (BlGGT) have been constructed by site-directed mutagenesis. The resultant enzymes were overexpressed in Escherichia coli and purified by affinity chromatography for biochemical and biophysical characterizations. Replacing Gly481 by either Ala or Glu did affect both autocatalytic processing and catalytic activity of the enzyme, but the substitution of this residue to arginine resulted in an unprocessed enzyme with insignificant catalytic activity. The replacement of another conserved glycine residue, Gly482, by either Ala or Glu caused a significant change in the functional integrity of the enzyme. Moreover, the mutation of Gly482 to arginine led to a marked reduction in the autocatalytic processing. Structural analyses revealed that the fluorescence and circular dichroism properties of mutant proteins were basically consistent with those of BlGGT. However, guanidine hydrochloride (GdnHCl)-induced transitions of most mutants were profoundly reduced in comparison with that of wild-type enzyme. Molecular modeling suggests that the conserved Gly481 and Gly482 residues of BlGGT are located at critical positions to create an environment suitable for both autoprocessing and catalytic reactions.

A thermally activated delayed fluorescent (TADF) emitter (DMAC-TRZ) was reported either as the emitting dopant in a host or as the non-doped (neat) emitting layer to achieve high EL EQEs of up to 26.5% and 20% in OLEDs, respectively.

Monodispersed gold nanoparticles (AuNPs) were simultaneously decorated with lactosylated and non-modified shorter poly(ethylene glycol)s (PEGs) to enhance their target recognition. The decoration with sufficiently shorter PEGs dramatically enhanced the multivalent binding ability of lactosylated AuNPs to the lectin-fixed surface, possibly due to the enhanced mobility of the ligands via the spacer effect generated by the shorter PEG chains.

Herein we describe the design and synthesis of a novel family of bifunctional, chiral bicyclo[2.2.1]heptadiene ligands bearing aryl and secondary amido groups, and demonstrate their usefulness in the Rh

Phytochemical investigation of the roots and stems of Illigera luzonensis afforded two new aporphine alkaloids (1) and (2), one new bisdehydroaporphine alkaloid (3), and one new benzenoid (4), along with 28 known structures. The structures of new compounds were elucidated by spectral and MS analysis. Among the isolated compounds, (1) and (4–13) were subjected into the examination for their inhibitory effects on the aggregation of washed rabbit platelets.

Phytochemical investigation of the heartwood of Michelia compressa afforded forty-four compounds, which were identified by comparison of experimental and literature analytical and spectroscopic data. Some compounds were evaluated for their anti-inflammatory and anticancer bioactivities. The result showed that soemerine (1) and cyathisterol (2) exhibited significant nitric oxide (NO) inhibition, with IC50 values of 8.5 ± 0.3 and 9.6 ± 0.5 µg/mL, respectively. In addition, liriodenine (3) and oliveroline (4) exhibited cytotoxicity to human nasopharyngeal carcinoma (NPC-TW01), non-small cell lung carcinoma (NCI-H226), T cell leukemia (Jurkat), renal carcinoma (A498), lung carcinoma (A549) and fibrosarcoma (HT1080) cell lines with IC50 values in the range of 15.7–3.68 μM.

Phytochemical investigation of the whole plants of Andrographis echioides afforded two new 2'-oxygenated flavonoids (1) and (2), two new phenyl glycosides (3) and (4), along with 37 known structures. The structures of new compounds were elucidated by spectral analysis and chemical transformation studies. Among the isolated compounds, (1–2) and (6–19) were subjected into the examination for their iNOS inhibitory bioactivity. The structure-activity relationships of the flavonoids for their inhibition of NO production were also discussed.

The authors wish to make two changes to their published paper [1]. The word “soemerine (1)” in the abstract, line 4, needs to be changed to “roemerine (1)”. The authors also wish to change the content of Figure 1 as shown below. The authors apologize for any inconvenience these changes may cause. Figure 1 Structure of compounds 1–4. The changes do not affect the scientific results. The manuscript will be updated and the original will remain online on the article webpage.

Complexes (R1Cp)(R2Ind)ZrCl2, the catalysts previously reported active for ethylene polymerization showed high activity in ethylene/1-hexene copolymerization and propylene polymerization in the presence of MAO. The content of 1-hexene in copolymers ranged from 1.2% to 3.2%. In propylene polymerization the complex 1 showed the highest activity, up to 1.2×106 g of polypropylene per mol of catalyst per hour. Based on the analysis of NMR spectral data, the relationships between complex structures and polymerization results were explored.

Two new glucosides, salviadigitoside A (1) and salviatalin A-19-O-β-glucoside (2), belonging to the salviatalin type diterpenoids, and a new cyclopenta[c]pyridine, salviadiginine A (3), were isolated from the roots of Salvia digitaloids. Structures of these compounds were determined on the basis of spectroscopic analysis. In addition, compounds 1–3 were evaluated for their anti-inflammatory activity, but the results showed a weak anti-inflammatory activity.

A new kind of Se-N dynamic covalent bond has been found that can form between the Se atom of a phenylselenyl halogen species and the N atom of a pyridine derivative, such as polystyrene-b-poly(4-vinylpyridine). This Se-N dynamic covalent bond can be reversibly and rapidly formed or cleaved under acidic or basic conditions, respectively. Furthermore, the bond can be dynamically cleaved by heating or treatment with stronger electron-donating pyridine derivatives. The multiple responses of Se-N bond to external stimuli has enriched the existing family of dynamic covalent bonds. It can be used for controlled and reversible self-assembly and disassembly, which may find potential applications in a number of areas, including self-healing materials and responsive assemblies.

Thermoresponsive spherical assemblies formed by a selenium-containing small molecule exhibit lower critical solution temperature (LCST) behavior in aqueous solution, which can be reversibly switched by mild redox treatment.

Highly uniform single crystal ultrathin CsPbBr3 nanowires (NWs) with diameter of 2.2 ± 0.2 nm and length up to several microns were successfully synthesized and purified using a catalyst-free colloidal synthesis method followed by a stepwise purification strategy. The NWs have bright photoluminescence (PL) with a photoluminescence quantum yield (PLQY) of about 30% after surface treatment. Large blue-shifted UV-vis absorption and PL spectra have been observed due to strong two-dimensional quantum confinement effects. A small angle X-ray scattering (SAXS) pattern shows the periodic packing of the ultrathin NWs along the radial direction, demonstrates the narrow radial distribution of the wires, and emphasizes the deep intercalation of the surfactants. Despite the extreme aspect ratios of the ultrathin NWs, their composition and the resulting optical properties can be readily tuned by an anion-exchange reaction with good morphology preservation. These bright ultrathin NWs may be used as a model system to study strong quantum confinement effects in a one-dimensional halide perovskite system.

As a cation-deficient, p-type semiconductor, copper sulfide (Cu(2-x)S) shows promise for applications such as photovoltaics, memristors, and plasmonics. However, these applications demand precise tuning of the crystal phase as well as the stoichiometry of Cu(2-x)S, an ongoing challenge in the synthesis of Cu(2-x)S materials for a specific application. Here, a detailed transformation diagram of cation-exchange (CE) chemistry from cadmium sulfide (CdS) into Cu(2-x)S nanowires (NWs) is reported. By varying the reaction time and the reactants' concentration ratio, the progression of the CE process was captured, and tunable crystal phases of the Cu(2-x)S were achieved. It is proposed that the evolution of Cu(2-x)S phases in a NW system is dependent on both kinetic and thermodynamic factors. The reported data demonstrate that CE can be used to precisely control the structure, composition, and crystal phases of NWs, and such control may be generalized to other material systems for a variety of practical applications.

To develop an experimental facility for reducing C2H4 produced by plants' growing in the controlled ecological life support system (CELSS).Based on technical parameters and performance requirements, project planning, design drawing, fabrication, and debug were conducted. Then, an experimental test for reducing C2H4 was done by measuring the content of C2H4 in gases between the inlet and the outlet of the facility. Its C2H4 decomposing capacity was evaluated.The facility worked well, and the parameters, such as energy consumption, and volume, met the design requirements. The experimental test results demonstrated that the content of C2H4 was reduced from 0.034 mg/kg to below 0.010 mg/kg, under the condition that the relative humidity and velocity of flow of the inlet-gas was 20% and 1.0-3.0 L/min respectively, and power of the lamp was 48 W. Considering the composition and the content of the gas in the outlet of the facility, there was no harmful product to the plants, except CO2 and H2O.The facility has reasonable technical indices, and smooth and dependable performances. It can be used as a facility for decomposing C2H4 in plants growing system in CELSS.

Objective. To develop a low temperature catalyst for the Sabatier CO2 reduction of the atmospheric regeneration system and lower the start-up temperature of the Sabatier reaction. Method. A low temperature catalyst was designed from the considerations of the active composition, the choice of the carrier, the production method and condition of the catalyst. Then the performance of the newly developed low temperature catalyst was tested. Result. A new low temperature catalyst for the Sabatier reaction using Ru as the active composition and using r-Al2O3 as the carrier was developed. The start-up temperature was lower than 110 degrees C and the start-up time was 8 min; The conversion efficiency of the lean component (H2 or CO2) was over 95 percent when the temperature of the reactor was from 200 degrees C to 300 degrees C; The reaction product water was nearly colorless, transparent and neutral. Conclusion. The test results showed that the goals of the design are achieved and it is worthwhile to make further studies on the low temperature catalyst.