Mechanism of CO2 in promoting the hydrogenation of levulinic acid to γ-valerolactone catalyzed by RuCl3 in aqueous solution.

A Ru-containing complex shows good catalytic performance toward the hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) with the assistance of organic base ligands (OBLs) and CO2. Herein, we report the competitive mechanisms for the hydrogenation of LA to GVL, 4-oxopentanal (OT), and 2-methyltetrahydro-2,5-furandiol (MFD) with HCOOH or H2 as the H source catalyzed by RuCl3 in aqueous solution at the M06/def2-TZVP, 6-311++G(d,p) theoretical level. Kinetically, the hydrodehydration of LA to GVL is predominant, with OT and MFD as side products. With HCOOH as the H source, initially, the OBL (triethylamine, pyridine, or triphenylphosphine) is responsible for capturing H+ from HCOOH, leading to HCOO- and [HL]+. Next, the Ru3+ site is in charge of sieving H- from HCOO-, yielding [RuH]2+ hydride and CO2. Alternatively, with H2 as the H source, the OBL stimulates the heterolysis of H-H bond with the aid of Ru3+ active species, producing [RuH]2+ and [HL]+. Toward the [RuH]2+ formation, H2 as the H source exhibits higher activity than HCOOH as the H source in the presence of an OBL. Thereafter, H- in [RuH]2+ gets transferred to the unsaturated C site of ketone carbonyl in LA. Afterwards, the Ru3+ active species is capable of cleaving the C-OH bond in 4-hydroxyvaleric acid, yielding [RuOH]2+ hydroxide and GVL. Subsequently, CO2 promotes Ru-OH bond cleavage in [RuOH]2+, forming HCO3- and regenerating the Ru3+-active species owing to its Lewis acidity. Lastly, between the resultant HCO3- and [HL]+, a neutralization reaction occurs, generating H2O, CO2, and OBLs. Thus, the present study provides insights into the promotive roles of additives such as CO2 and OBLs in Ru-catalyzed hydrogenation.

Selective Stereoretention of Carbohydrates upon C-C Cleavage Enabling D-Glyceric Acid Production with High Optical Purity over a Ag/γ-Al2O3 Catalyst.

Chiral carboxylic acid production from renewable biomass by chemocatalysis is vitally important for reducing our carbon footprint, but remains underdeveloped. We herein establish a strategy that make use of a stereogenic center of biomass to achieve a rare example of D-glyceric acid production with the highest yield (86.8 %) reported to date as well as an excellent ee value (>99 %). Unlike traditional asymmetric catalysis, chiral catalysts/additives are not required. Ample experiments combined with quantum chemical calculations established the origins of the stereogenic center and catalyst performance. The chirality at C4 in D-xylose was proved to be retained and successfully delivered to C2 in D-glyceric acid during C-C cleavage. The remarkable cooperative-roles of Ag+ and Ag0 in the constructed Ag/γ-Al2O3 catalyst are disclosed as the crucial contributors. Ag+ was responsible for low-temperature activation of D-xylose, while Ag0 facilitated the generation of active O* from O2. Ag+ and active O* cooperatively promoted the precise cleavage of the C2-C3 bond, and more importantly O* allowed the immediate fast oxidization of the D-glyceraldehyde intermediate to stabilize D-glyceric acid, thereby inhibiting the side reaction that induced racemization. This strategy makes a significant breakthrough in overcoming the limitation of poor enantioselectivity in current chemocatalytic conversion of biomass.

Toxicity of tigecycline on the freshwater microalga Scenedesmus obliquus: Photosynthetic and transcriptional responses.

Tigecycline (TGC) is a new tetracycline antibiotic medication against multidrug-resistant bacteria. However, the toxicity of TGC to microalgae remains largely unknown. In this study, the toxicity of TGC on Scenedesmus obliquus was examined, focusing on changes in algal growth, photosynthetic activity, and transcriptome. According to an acute toxicity test, the IC10 and IC50 values were 0.72 mg/L and 4.15 mg/L, respectively. Analyses of photosynthetic efficiency and related parameters, such as light absorption, energy capture, and electron transport, identified a 35% perturbation in the IC50 group, while the IC10 group remained largely unaffected. Transcriptomic analysis showed that in the IC10 and IC50 treatment groups, there were 874 differentially expressed genes (DEGs) (220 upregulated and 654 downregulated) and 4289 DEGs (2660 upregulated and 1629 downregulated), respectively. Gene Ontology enrichment analysis showed that TGC treatment markedly affected photosynthesis, electron transport, and chloroplast functions. In the IC50 group, a clear upregulation of genes related to photosynthesis and chloroplast functions was observed, which could be an adaptive stress response. In the IC10 group, significant downregulation of DEGs involved in ribosomal pathways and peptide biosynthesis processes was observed. Kyoto Encyclopedia of Gene and Genomes enrichment analysis showed that treatment with TGC also disrupted energy production, protein synthesis, and metabolic processes in S. obliquus. Significant downregulation of key proteins related to Photosystem II was observed under the IC10 TGC treatment. Conversely, IC50 TGC treatment resulted in substantial upregulation across a broad array of photosystem-related proteins from both Photosystems II and I. IC10 and IC50 TGC treatments differentially influenced proteins involved in the photosynthetic electron transport process. This study emphasizes the potential risks of TGC pollution to microalgae, which contributes to a better understanding of the effects of antibiotic contamination in aquatic ecosystems.

Production of Oximes Directly from Sustainable Lignocellulose-Derived Aldehydes and Ammonia over HTS-1 Catalyst.

Oxime chemicals are the building blocks of many anticancer drugs and widely used in industry and laboratory. A simple but robust hierarchically porous zeolite (HTS-1) catalyst was prepared by hydrothermal methods and used for the preparation of vanillin oxime from vanillin in NH3 ⋅ H2 O/DIO (v/v 1/10) system. The results of the catalyst characterization showed that the larger pore size and more framework Ti were conducive to promote the transformation of the substrates. The conversion of vanillin and the yield of vanillin oxime were both higher than 99 % under optimized reaction conditions. It was found that the reaction proceeded by oxidation of NH3 to hydroxylamine (NH2 OH), and oximation of hydroxylamine with vanillin to obtain vanillin oxime, where the rate-controlling step was the hydroxylamine formation, and the apparent activation energy was 26.22 kJ/mol. The corresponding oximation products could also be obtained by extending this method to other compounds derived from lignin. Furthermore, the catalytic system was used directly to the conversion of birch biomass to obtain oxime products such as vanillin oxime, syringaldehyde oxime, and furfural oxime etc. This work might give insights into the sustainable production of N-containing high-value products from lignocellulose.

Effects of polystyrene microplastics on Euglena gracilis: Intracellular distribution and the protozoan transcriptional responses.

Microplastics (MPs) introduced into aquatic environments inevitably interact with aquatic organisms such as plankton, potentially yielding adverse effects on the aquatic ecosystem. The extent to which MPs can infiltrate planktonic cells and evoke a molecular response remains largely unknown. In the present study, the internalization of fluorescently labeled polystyrene (PS) MPs on Euglena gracilis cells was investigated, determining the transcriptional responses within protozoa after an 8-day exposure period. The results showed that exposure to 25 mg/L PS-MPs for 8 days, significantly inhibited protozoan growth (P < 0.05) and decreased the chlorophyll a content of E. gracilis. The photosynthetic efficiency of E. gracilis was suppressed by MPs after 4 days, and then recovered to control values by the eighth day. Fluorescence imaging confirmed the presence of MPs in E. gracilis. Transcriptomic analysis revealed the influence of PS-MPs on a diverse range of transcriptional processes, encompassing oxidative phosphorylation, oxidation-reduction process, photosynthesis, and antioxidant enzymes. Notably, a majority of the differentially expressed genes (DEGs) exhibited down-regulation. Furthermore, PS-MPs disturbed the transcriptional regulation of chloroplasts and photosynthesis. These findings indicate a direct interaction between PS-MPs and organelles within E. gracilis cells following internalization, thereby disrupting regular gene expression patterns and posing a substantial environmental risk to the aquatic ecosystem.

Photoswitchable and long-lived seven-membered cyclic singlet diradicals for the bioorthogonal photoclick reaction.

Annularly 1,3-localized singlet diradicals are energetic and homolytic intermediates, but commonly too short-lived for widespread utilization. Herein, we describe a direct observation of a long-lived and seven-membered singlet diradical, oxepine-3,6-dione-2,7-diyl (OXPID), via spectroscopic experiments and also theoretical evidence from computational studies, which is generated via photo-induced ring-expansion of 2,3-diaryl-1,4-naphthoquinone epoxide (DNQO). The photo-generated OXPID reverts to the thermally stable σ-bonded DNQO with t1/2 in the µs level, thus constituting a novel class of T-type molecular photoswitches with high light-energy conversion efficiency (η = 7.8-33%). Meanwhile, the OXPID is equilibrated to a seven-membered cyclic 1,3-dipole as an electronic tautomer that can be captured by ring-strained dipolarophiles with an ultrafast cycloaddition rate (k2CA up to 109 M-1 s-1). The T-type photoswitchable DNQO is then exploited to be a highly selective and recyclable photoclick reagent, enabling spatiotemporal-resolved bioorthogonal ligation on living cell membranes via a tailored DNQO-Cy3 probe.

Enhancement of carbon nanotubes on microalgal-fungal consortium formation and wastewater treatment.

As a promising material with an efficient light capture capability, a low amount of carbon nanotubes can affect growth and photosynthesis by regulating microalgal cells, thereby enhancing the pollutant removal efficiency in wastewater. In this study, microalgal-fungal consortia of Chlorella vulgaris and Ganoderma lucidum were developed with different types and concentrations of carbon nanotubes. The treatment effect of microalgal-fungal consortia on simulated digestate was also studied. The results demonstrate that 1.5 mg/L of carboxylated multi-walled carbon nanotubes remarkably promoted the formation, growth and photosynthesis of consortium. The dry weight and chlorophyll a content reached 19.3 ± 0.53 mg/symbiont and 27.3 ± 0.52 µg/L, respectively. Moreover, the removal efficiency of chemical oxygen demand, total nitrogen, total phosphorus and tetracycline hydrochloride were 94.1%, 65.5%, 61.9% and 96.2%, respectively. Overall, these findings suggest a promising future for the use of carbon nanotubes in wastewater treatment by regulating microalgal-fungal consortia.

Influence of Different Treatments on the Structure and Conversion of Silicon Species in Rice Straw to Tetraethyl Orthosilicate (TEOS).

The production of tetraethyl orthosilicate (TEOS) from biomass provides a new way for TEOS production and biomass valorization. In this study, rice straw was treated using different fractionation methods, and the content, state, and reactivity of Si in the treated samples were investigated. It was found that acid treatment and ethanol extraction kept most Si in the biomass, while alkali treatment caused significant Si loss. Si was mainly present in the SiOx , Si-O-C, and Si-O-Si states in the surface of raw rice straw, cellulose and Klason lignin. The results showed that the Si-O-Si state in rice straw was beneficial for the formation of TEOS. The removal of lipids from rice straw facilitated the production of TEOS, giving the highest TEOS yield of 76.2 %. In contrast, the production of TEOS from other samples became difficult; the simultaneous conversion of the three organic components of rice straw also facilitated the production of TEOS.

Cooperative Catalysis Mechanism of Brønsted and Lewis Acids from Al(OTf)3 with Methanol for ß-Cellobiose-to-Fructose Conversion: An Experimental and Theoretical Study.

Al-containing catalysts, e.g., Al(OTf)3, show good catalytic performance toward the conversion of cellulose to fructose in methanol solution. Here, we report the catalytic isomerization and alcoholysis mechanisms for the conversion of cellobiose to fructose at the PBE0/6-311++G(d,p), aug-cc-pVTZ theoretical level, combining the relevant experimental verifications of electrospray ionization mass spectrometry (ESI-MS), high-performance liquid chromatography (HPLC), and the attenuated total reflection-infrared (ATR-IR) spectra. From the alcoholysis of Al(OTf)3 in methanol solution, the catalytically active species involves both the [CH3OH2]+ Brønsted acid and the [Al(CH3O)(OTf)(CH3OH)4]+ Lewis acid. There are two reaction pathways, i.e., one through glucose (glycosidic bond cleavage followed by isomerization, w-G) and another through cellobiulose (isomerization followed by glycosidic bond cleavage, w-L). The Lewis acid ([Al(CH3O)(OTf)(CH3OH)4]+) is responsible for the aldose-ketose tautomerization, while the Brønsted acid ([CH3OH2]+) is in charge of ring-opening, ring-closure, and glycosidic bond cleavage. For both w-G and w-L, the rate-determining steps are related to the intramolecular [1,2]-H shift between C1-C2 for the aldose-ketose tautomerization catalyzed by the [Al(CH3O)(OTf)(CH3OH)4]+ species. The Lewis acid ([Al(CH3O)(OTf)(CH3OH)4]+) exhibits higher catalytic activity toward the aldose-ketose tautomerization of glycosyl-chain-glucose to glycosyl-chain-fructose than that of chain-glucose to chain-fructose. Besides, the Brønsted acid ([CH3OH2]+) shows higher catalytic activity toward the glycosidic bond cleavage of cellobiulose than that of cellobiose. Kinetically, the w-L pathway is predominant, whereas the w-G pathway is minor. The theoretically proposed mechanism has been experimentally testified. These insights may advance on the novel design of the catalytic system toward the conversion of cellulose to fructose.

Theoretical Study on Cooperation Catalysis of Chiral Guanidine/ Copper(I) in Asymmetric Azide-Alkyne Cycloaddition/[2 + 2] Cascade Reaction.

Density functional theory (DFT) calculations with BP86-D3(BJ) functionals were employed to reveal the mechanism and stereoselectivity of chiral guanidine/copper(I) salt-catalyzed stereoselective three-component reaction among N-sulfonyl azide, terminal alkyne, and isatin-imine for spiroazetidinimines that was first reported by Feng and Liu (Angew. Chem. Int. Ed. 2018, 57, 16852-16856). For the noncatalytic cascade reaction, the denitrogenation to generate ketenimine species was the rate-determining step, with an activation barrier of 25.8-34.8 kcal mol-1. Chiral guanidine-amide promoted the deprotonation of phenylacetylene, generating guanidine-Cu(I) acetylide complexes as active species. In azide-alkyne cycloaddition, copper acetylene coordinated to the O atom of the amide moiety in guanidium, and TsN3 was activated by hydrogen bonding, affording the Cu(I)-ketenimine species with an energy barrier of 3.5∼9.4 kcal mol-1. The optically active spiroazetidinimine oxindole was constructed via a stepwise four-membered ring formation, followed by deprotonation of guanidium moieties for C-H bonding in a stereoselective way. The steric effect of the bulky CHPh2 group and chiral backbone in the guanidine, combined with the coordination between the Boc group in isatin-imine with a copper center, played important roles in controlling the stereoselectivity of the reaction. The major spiroazetidinimine oxindole product with an SS configuration was formed in a kinetically more favored way, which was consistent with the experimental observation.

Photo-induced defluorination acyl fluoride exchange as a fluorogenic photo-click reaction for photo-affinity labeling.

Photo-click chemistry has emerged as a powerful tool for revolutionizing bioconjugation technologies in pharmacological and various biomimetic applications. However, enriching the photo-click reactions to expand the bioconjugation toolkit remains challenging, especially when focusing on spatiotemporal control endowed by light activation. Herein, we describe a photo-induced defluorination acyl fluoride exchange (photo-DAFEx) as a novel type of photo-click reaction that is mediated through acyl fluorides produced by the photo-defluorination of m-trifluoromethylaniline to covalently conjugate with primary/secondary amines and thiols in an aqueous environment. (TD)-DFT calculations, together with experimental discovery, indicate that the m-NH2PhF2C(sp3)-F bond in the excited triplet state is cleaved by water molecules, which is key to inducing defluorination. Intriguingly, the benzoyl amide linkages built by this photo-click reaction exhibited a satisfactory fluorogenic performance, which allowed visualization of its formation in situ. Accordingly, this photo-controlled covalent strategy was exploited not only for the decoration of small molecules, peptide cyclization and functionalization of proteins in vitro, but also for designing photo-affinity probes targeting endogenous carbonic anhydrase II (hCA-II) in living cells.

Immune Checkpoint Inhibitors in HBV-Caused Hepatocellular Carcinoma Therapy.

Hepatitis B virus (HBV) infection is the main risk factor for the development of hepatocellular carcinoma (HCC), the most common type of liver cancer, with high incidence and mortality worldwide. Surgery, liver transplantation, and ablation therapies have been used to treat early HBV-caused HCC (HBV-HCC); meanwhile, in the advanced stage, chemoradiotherapy and drug-targeted therapy are regularly considered, but with limited efficacy. Recently, immunotherapies, such as tumor vaccine therapy, adoptive cell transfer therapy, and immune checkpoint inhibitor therapy, have demonstrated promising efficacy in cancer treatment. In particular, immune checkpoint inhibitors can successfully prevent tumors from achieving immune escape and promote an anti-tumor response, thereby boosting the therapeutic effect in HBV-HCC. However, the advantages of immune checkpoint inhibitors in the treatment of HBV-HCC remain to be exploited. Here, we describe the basic characteristics and development of HBV-HCC and introduce current treatment strategies for HBV-HCC. Of note, we review the principles of immune checkpoint molecules, such as programmed cell death protein 1(PD-1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) in HBV-HCC, as well as related inhibitors being considered in the clinic. We also discuss the benefits of immune checkpoint inhibitors in the treatment of HBV-HCC and the efficacy of those inhibitors in HCC with various etiologies, aiming to provide insights into the use of immune checkpoint inhibitors for the treatment of HBV-HCC.

Coordination of sorbitol to Ga(OTf)3 in the liquid phase: an experimental and theoretical study.

In a solution of sorbitol (SBT) and Ga(OTf)3 compounds, the coordination of sorbitol (SBT) to [Ga(OTf)n]3-n (n = 0-3) has been investigated, using both ESI-MS spectra and density functional theory (DFT) calculations at the M06/6-311++g(d,p), aug-cc-pvtz level using a polarized continuum model (PCM-SMD). In sorbitol solution, the most stable conformer of sorbitol includes three intramolecular H-bonds, i.e., O2H⋯O4, O4H⋯O6, and O5H⋯O3. Through ESI-MS spectra, in a tetrahydrofuran solution of both SBT and Ga(OTf)3 compounds, five main species are observed, i.e., [Ga(SBT)]3+, [Ga(OTf)]2+, [Ga(SBT)2]3+, [Ga(OTf)(SBT)]2+, and [Ga(OTf)(SBT)2]2+. Through DFT calculations, in a solution of sorbitol (SBT) and Ga(OTf)3 compounds, the Ga3+ cation tends to form five six-coordination complexes, i.e., [Ga(η2O,O-OTf)3], [Ga(η3O2-O4-SBT)2]3+, [(η2O,O-OTf)Ga(η4O2-O5-SBT)]2+, [(η1O-OTf)(η2O2,O4-SBT)Ga(η3O3-O5-SBT)]2+, and [(η1O-OTf)(η2O,O-OTf)Ga(η3O3-O5-SBT)]+, which are in good agreement with the experimental observation of the ESI-MS spectra. For both [Ga(OTf)n]3-n (n = 1-3) and [Ga(SBT)m]3+ (m = 1, 2) complexes, the negative charge transfer from ligands to the Ga3+-center plays an important role in their stability, because of the strong polarization of the Ga3+ cation. For [Ga(OTf)n(SBT)m]3-n (n = 1, 2; m = 1, 2) complexes, the negative charge transfer from ligands to the Ga3+-center plays an essential role in their stability, accompanied by an electrostatic interaction between the Ga3+-center and ligands and/or spatial inclusion of ligands toward the Ga3+-center.

Orientated inhibition of humin formation in efficient production of levulinic acid from cellulose with high substrate loading: Synergistic role of additives.

The main bottleneck in the direct conversion of cellulose to levulinic acid (LA), a promising bio-based platform chemical, lies in the severe formation of humins, especially at high substrate loading (>10 wt%). Herein, we report an efficient catalytic system consisting of a 2-methyltetrahydrofuran/water (MTHF/H2O) biphasic solvent with NaCl and cetyltrimethylammonium bromide (CTAB) as additives for converting cellulose (15 wt%) to LA in the presence of a benzenesulfonic acid catalyst. We show that both NaCl and CTAB accelerated the depolymerization of cellulose and formation of LA. However, NaCl favored the humin formation via degradative condensations, whereas CTAB inhibited humin formation by restraining the routes of both degradative and dehydrated condensations. A synergistic role of NaCl and CTAB on suppressing humin formations is illustrated. The combined use of NaCl and CTAB led to an increased LA yield (60.8 mol%) from microcrystalline cellulose in MTHF/H2O (VMTHF/VH2O = 2/1) at 453 K for 2 h. Moreover, it was efficient for converting cellulose fractioned from several kinds of lignocellulosic biomass, wherein a high LA yield of 81.0 mol% was achieved from wheat straw cellulose. This work presents a new strategy for advancing LA biorefinery by synergistically promoting cellulose depolymerization with orientated inhibition of undesired humin formation.

Complete Low-Temperature Transformation and Dissolution of the Three Main Components in Corn Straw.

The conversion of biomass faces the challenge of mass and heat transfer, as well as the exertion of heterogeneous catalyst, because raw biomass exists usually in solid state. In this work, the simultaneous transformation and dissolution of the three main components (hemicellulose, cellulose, lignin) in corn straw were achieved in ethanol/ valerolactone (GVL)/H2 O (10 : 10 : 40, v/v/v) co-solvent system. With the assistance of AlCl3 ⋅ 6H2 O, the conversion of hemicellulose, lignin and cellulose was >96 % at 170 °C. The conversion of solid biomass into fluid, overcoming the mass transfer restrictions between solid biomass and solid catalysts, provides new raw materials to further upgrading. H2 O could penetrate inside the crystalline cellulose to swell even dissolve it, while ethanol and GVL acted as media to dissolve especially the G unit in lignin. The H+ derived from AlCl3 ⋅ 6H2 O hydrolysis could break the linkages of lignin-hemicellulose and glycosidic bond in saccharides, and aluminum chloride promoted the next degradation of polysaccharides to small molecules. Consequently, as high as 33.2 % yield of levulinic acid and 42.2 % yield of furfural were obtained. The cleavage of ß-O-4 and Cß -Cγ bonds in lignin produced large amounts of lignin-derived dimers and trimers. The total yield of monomeric phenols is up to 8 %.

Removal of tetracycline from water by catalytic photodegradation combined with the microalga Scenedesmus obliquus and the responses of algal photosynthesis and transcription.

The antibiotic tetracycline (TC) and its degradation products (TDPs) in degradation solution present serious environmental problems, such as human health damage and ecological risk; thus further treatment is required before being released into the aquatic environment. Furthermore, their environmental impact on microalgae remains unclear. In this study, TC was degraded by photocatalysis using birnessite and UV irradiation, followed by biological purification using the microalga Scenedesmus obliquus. In addition, the photosynthetic activity and transcription of the microalgae were examined to evaluate the toxicity of TC and TDPs. The results show that photocatalytic degradation efficiency reached 92.7% after 30 min, and 11 intermediate products were detected. The microalgae achieved a high TC removal efficiency (99.7%) after 8 days. Exposure to the degraded TC solution (D) resulted in significantly lower (p < 0.05) biomass than the pure TC (T), and S. obliquus in the T treatment showed better resilience than the D treatment. Transcriptomic assays for different treatments revealed differential gene expression mainly involving the photosynthesis, ribosome, translation and peptide metabolic progresses. The up-regulation of photosynthesis-related genes and differential expression of chloroplast genes may be important for S. obliquus to acquire high photosynthetic efficiency and growth recovery when exposed to TC and TDPs. Our study provides a reference for TC removal using a combination of catalytic degradation and microalgal purification, and it is also helpful for understanding the environmental risk of TDPs in natural aquatic environments.

MGEL: Multigrained Representation Analysis and Ensemble Learning for Text Moderation.

In this work, we describe our efforts in addressing two typical challenges involved in the popular text classification methods when they are applied to text moderation: the representation of multibyte characters and word obfuscations. Specifically, a multihot byte-level scheme is developed to significantly reduce the dimension of one-hot character-level encoding caused by the multiplicity of instance-scarce non-ASCII characters. In addition, we introduce a simple yet effective weighting approach for fusing n-gram features to empower the classical logistic regression. Surprisingly, it outperforms well-tuned representative neural networks greatly. As a continual effort toward text moderation, we endeavor to analyze the current state-of-the-art (SOTA) algorithm bidirectional encoder representations from transformers (BERT), which works well in context understanding but performs poorly on intentional word obfuscations. To resolve this crux, we then develop an enhanced variant and remedy this drawback by integrating byte and character decomposition. It advances the SOTA performance on the largest abusive language datasets as demonstrated by our comprehensive experiments. Our work offers a feasible and effective framework to tackle word obfuscations.

Enhanced Fatty Acid Photodecarboxylation over Bimetallic Au-Pd Core-Shell Nanoparticles Deposited on TiO2.

Photodecarboxylation of biomass-derived fatty acids to alkanes offers significant potential to obtain hydrocarbons and economic benefits due to the mild conditions and high activity. Herein, the photodecarboxylation of hexanoic acid into alkanes using TiO2-supported monometallic Au or Pd and bimetallic Au-Pd catalysts is reported. It was found that bimetallic Au-Pd catalysts, featuring a core-shell structure evidenced by EDX-mapping and element line profile, show better photocatalytic performance, achieving 94.7% conversion of hexanoic acid and nearly 100% selectivity to pentane under UV-vis irradiation in the absence of H2 than the monometallic Au analogue. This remarkable enhancement in activity compared to its TiO2 supported monometallic Au or Pd analogues can be attributed to the synergistic effect between Au and Pd within the nanostructured Au(core)-Pd(shell) alloy for achieving more efficient charge-separation efficiency upon visible light excitation. This photocatalyst exhibits a wide scope converting multiple fatty acids into hydrocarbons. Moreover, it can even photocatalyze the conversion of raw bio-oils into alkanes directly. No obvious activity loss was observed during the reusability tests, demonstrating the good stability of the present catalyst. Density functional theory (DFT) calculations indicate that oxidation of carboxylates on TiO2 leads to alkyl radicals that become bound to metal nanoparticles. The superior catalytic performance of Au(core)-Pd(shell)/TiO2 is derived from the weaker adsorption for H on the alloy and the lower hydrogen evolution reaction overpotential. Our research can result in an efficient bio-oil upgrading, resulting in the synthesis of biofuels from biomass under mild conditions.

Effects of Tetracycline on Scenedesmus obliquus Microalgae Photosynthetic Processes.

Tetracycline (TC) antibiotics can be detected worldwide in the aquatic environment due to their extensive use and low utilization efficiency, and they may affect the physiological processes of non-target organisms. In this study, the acute and sub-acute toxicities of TC on the freshwater microalga Scenedesmus obliquus were investigated with an emphasis on algal photosynthesis and transcription alterations during an 8 d TC exposure. The results showed that the IC10, IC30 and IC50 values were 1.8, 4.1 and 6.9 mg/L, respectively. During sub-acute exposure, the microalgae of the IC10 treatment was able to recover comparable growth to that of the control by day 7, while significantly lower cell densities were observed in the IC30 and IC50 treatments at the end of the exposure. The photosynthetic efficiency Fv/FM of S. obliquus first decreased as the TC concentration increased and then returned to a level close to that of the control on day 8, accompanied by an increase in photosynthetic activities, including light harvesting, electron transport and energy dissipation. Transcriptomic analysis of the IC10 treatment (1.8 mg/L TC) revealed that 2157 differentially expressed genes were up-regulated and 1629 were down-regulated compared with the control. KEGG and GO enrichments demonstrated that 28 photosynthesis-related genes involving light-harvesting chlorophyll protein complex, photosystem I, photosystem II, photosynthetic electron transport and enzymes were up-regulated, which may be the factor responsible for the enhanced photosynthesis and recovery of the microalgae. Our work may be helpful not only for gaining a better understanding of the environmental risk of TC at concentrations close to the real levels in natural waters, but also for explaining photosynthesis and related gene transcription induced by antibiotics.

Glycerol Valorization Towards Glycolic Acid Production Over Cu-Based Biochar Catalyst.

Glycerol valorization towards high-value chemicals is of particular importance to increase the value chain of biodiesel production. In this study, the catalytic activity of a series of cheap Cu-based catalysts for glycerol conversion is investigated. Cu supported on activated carbon (AC, obtained through carbonization of coconut shell) exhibits outstanding catalytic activity for the selective conversion of glycerol into glycolic acid (GcA) in O2 atmosphere, affording up to 68.3 % GcA yield. The combination of experimental results with theoretical calculations reveals that glyceraldehyde is the key reaction intermediate. The high specific surface area and surface oxygenated groups of AC enable the formation of CuO nanoparticles with small size and uniform dispersion. In addition, the surface oxygen vacancy on Cu/AC might help to activate reaction intermediates, and the electron transfer from Cu to AC facilitates the oxidation of glycerol to GcA. Cu loaded onto AC also significantly inhibits C-C breakage to generate formic acid as a byproduct. This work might aid the development of approaches for glycerol application and afford profitable possibilities for sustainable biodiesel.