Synthesis of a novel Si-N-S flame retardant and its application on cotton cellulose biomacromolecule.

A novel flame retardant containing Si, N, and S elements, ((2-(triethoxysilyl)ethyl)thio)ethan-1-amine hydrochloride (TETEA), was synthesized via a click reaction and characterized using nuclear magnetic resonance spectroscopy (NMR) and fourier transform infrared spectroscopy (FTIR). Subsequently, the flame-retardant cotton fabric was fabricated by sol-gel method. The results indicated that TETEA was successfully loaded on cotton fabric and formed a uniform protective layer on the surface of cotton fabric, exhibiting excellent flame retardancy. The flame-retardant cotton fabric achieved limiting oxygen index (LOI) of 28.3 % and passed vertical combustion test without after-flame or afterglow time at TETEA concentration of 500 g/L. Thermogravimetric analysis revealed that the residual carbon content of the flame-retardant cotton fabric was much higher than that of the control under air and N2 conditions. Besides, the flame-retardant cotton fabric was not ignited in cone calorimeter test with an external heat flux of 35 kW/m2. The peak heat release rate and the total heat release decreased from 133.4 kW/m2 to 25.8 kW/m2 and from 26.46 MJ/m2 to 17.96 MJ/m2, respectively. This phosphorus-free flame retardant offers a simplified synthesis process without adverse environmental impacts, opening up a new avenue for the development environmentally friendly flame retardants compared to traditional alternatives.

Signaling pathways in the treatment of Alzheimer's disease with acupuncture: a narrative review.

BACKGROUND: To date, there is no effective treatment for Alzheimer's disease (AD), a progressive neurodegenerative disorder that is increasing in prevalence worldwide. The objective of this review was to summarize the core targets and signaling pathways involved in acupuncture treatment for AD. METHODS: We reviewed numerous signaling pathways, including mammalian target of rapamycin (mTOR), phosphatidylinositol 3-kinase-protein kinase B (PI3 K/Akt), adenosine monophosphate-activated protein kinase (AMPK), mitogen-activated protein kinase (MAPK), nuclear factor (NF)-kB, p53, Wnt, nitric oxide (NO), Janus kinase / signal transducer and activator of transcription (JAK/ STAT), RhoA/ROCK (Rho-associated protein kinase) and Ca2+/ calmodulin-dependent protein kinase II (CaMKII) / cyclic adenosine monophosphate-response element-binding protein (CREB). The relevant data were obtained from PubMed, EMBASE, Web of Science, China National Knowledge Infrastructure (CNKI) and Wanfang databases. RESULTS: In summary, the effects of acupuncture are mediated by multiple targets and pathways. Furthermore, acupuncture can improve pathological changes associated with AD (such as abnormal deposition of amyloid (A)ß, tau hyperphosphorylation, synaptic dysfunction and neuronal apoptosis) through multiple signaling pathways. CONCLUSION: Overall, our findings provide a basis for future research into the effects of acupuncture on AD.

Whole-cell one-pot biosynthesis of dodecanedioic acid from renewable linoleic acid.

BACKGROUND: Dodecanedioic acid (DDA), a typical medium-chain dicarboxylic fatty acid with widespread applications, has a great synthetic value and a huge industrial market demand. Currently, a sustainable, eco-friendly and efficient process is desired for dodecanedioic acid production. RESULTS: Herein, a multi-enzymatic cascade was designed and constructed for the production of DDA from linoleic acid based on the lipoxygenase pathway in plants. The cascade is composed of lipoxygenase, hydroperoxide lyase, aldehyde dehydrogenase, and unidentified double-bond reductase in E. coli for the main cascade reactions, as well as NADH oxidase for cofactor recycling. The four component enzymes involved in the cascade were co-expressed in E. coli, together with the endogenous double-bond reductase of E. coli. After optimizing the reaction conditions of the rate-limiting step, 43.8 g L- 1 d- 1 of DDA was obtained by a whole-cell one-pot process starting from renewable linoleic acid. CONCLUSIONS: Through engineering of the reaction system and co-expressing the component enzymes, a sustainable and eco-friendly DDA biosynthesis route was set up in E. coli, which afforded the highest space time yield for DDA production among the current artificial multi-enzymatic routes derived from the LOX-pathway, and the productivity achieved here ranks the second highest among the current research progress in DDA biosynthesis.

Remodeling the Homologous Recombination Mechanism of Yarrowia lipolytica for High-Level Biosynthesis of Squalene.

Squalene is a high-value antioxidant with many commercial applications. The use of microbial cell factories to produce squalene as an alternative to plant and animal extracts could meet increasing market demand. Yarrowia lipolytica is an excellent host for squalene production due to its high levels of acetyl-CoA and a hydrophobic environment. However, the need for precise and complicated gene editing has hindered the industrialization of this strain. Herein, the rapid construction of a strain with high squalene production was achieved by enhancing the homologous recombination efficiency in Y. lipolytica. First, remodeling of the homologous recombination efficiency resulted in a 10-fold increase in the homologous recombination rate. Next, the whole mevalonate pathway was integrated into the chromosome to enhance squalene production. Then, a higher level of squalene accumulation was achieved by increasing the level of acetyl coenzyme A and regulating the downstream steroid synthesis pathway. Finally, the squalene production reached 35 g/L after optimizing the fermentation conditions and performing a fed-batch culture in a 5 L jar fermenter. This is the highest squalene production ever reported to date by de novo biosynthesis without adding any inhibitors, paving a new path toward the industrial production of squalene and its downstream products.

Trends in the application of "omics" to Alzheimer's disease: a bibliometric and visualized study.

BACKGROUND: Alzheimer's disease (AD) is a progressive neurodegenerative disease with an insidious onset. The widespread application of omics techniques in AD has attracted considerable attention. We aimed to make a comprehensive analysis of published omics articles on AD in order to determine the research profile and application trends of omics techniques in AD. METHODS: This study utilizes bibliometric and visual methods including a map collaboration map, co-citations, and keywords to identify knowledge structures, hot topics, and research trends based on 6,828 publications from the Web of Science Core Collection (WoSCC) database. RESULTS: The results of this study showed that 5654 institutions from 91 countries published articles in this field. The USA, China, and the UK played a leading role in publishing numerous articles in relevant journals as well as prolific institutions and authors, respectively. This paper collects a large number of literatures on the application of AD omics technology from the WoSCC database and found the omics technology applied to AD is mainly based on genomics technology. The application of transcriptomics technology has shown an increasing trend in recent years, and the application of multi-omics technology will be the general trend in the future. CONCLUSION: The development status, frontier hotspots, and general trends of omics application technologies are reviewed. This article will provide intelligence support to researchers and institutions in the field of Alzheimer's omics research and applications from a practical perspective.

Identification of key proteins as potential biomarkers associated with post-infarction complications in diabetics.

Background: The ability of transcriptome analysis to identify dysregulated pathways and outcome-related genes following myocardial infarction in diabetic patients remains unknown. The present study was designed to detect possible biomarkers associated with the incidence of post-infarction complications in diabetes to assist thedevelopment of novel treatments for this condition.Methods: Two gene expression datasets, GSE12639 and GSE6880, were downloaded from the Gene Expression Omnibus (GEO) database, and then differentially expressed genes (DEGs) were identified between post-infarction diabetics and healthy samples from the left ventricular wall of rats. These DEGs were then arranged into a protein-protein interaction (PPI) network, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and Gene Ontology (GO) enrichment analyses were performed to explore the functional roles of these genes.Results: In total, 30 DEGs (14 upregulated and 16 downregulated) were shared between these two datasets, as identified through Venn diagram analyses. GO analyses revealed these DEGs to be significantly enriched in ovarian steroidogenesis, fatty acid elongation, biosynthesis of unsaturated fatty acids, synthesis and degradation of ketone bodies, and butanoate metabolism. The PPI network of the DEGs had 14 genes and 70 edges. We identified two key proteins, 3-hydroxymethylglutaryl-CoA synthase 2 (Hmgcs2) and Δ3, Δ2-Enoyl-CoA Delta Isomerase 1 (ECI1), and the upregulated gene Hmgcs2 with the highest score in the MCC method. We generated a co-expression network for the hub genes and obtained the top ten medications suggested for infarction with diabetes.Conclusion: Taken together, the findings of these bioinformatics analyses identified key hub genes associated with the development of myocardial infarction in diabetics. These hub genes and potential drugs may become novel biomarkers for prognosis and precision treatment in the future.

Machine-Learning-Guided Engineering of an NADH-Dependent 7ß-Hydroxysteroid Dehydrogenase for Economic Synthesis of Ursodeoxycholic Acid.

Enzymatic synthesis of ursodeoxycholic acid (UDCA) catalyzed by an NADH-dependent 7ß-hydroxysteroid dehydrogenase (7ß-HSDH) is more economic compared with an NADPH-dependent 7ß-HSDH when considering the much higher cost of NADP+/NADPH than that of NAD+/NADH. However, the poor catalytic performance of NADH-dependent 7ß-HSDH significantly limits its practical applications. Herein, machine-learning-guided protein engineering was performed on an NADH-dependent Rt7ß-HSDHM0 from Ruminococcus torques. We combined random forest, Gaussian Naïve Bayes classifier, and Gaussian process regression with limited experimental data, resulting in the best variant Rt7ß-HSDHM3 (R40I/R41K/F94Y/S196A/Y253F) with improvements in specific activity and half-life (40 °C) by 4.1-fold and 8.3-fold, respectively. The preparative biotransformation using a "two stage in one pot" sequential process coupled with Rt7ß-HSDHM3 exhibited a space-time yield (STY) of 192 g L-1 d-1, which is so far the highest productivity for the biosynthesis of UDCA from chenodeoxycholic acid (CDCA) with NAD+ as a cofactor. More importantly, the cost of raw materials for the enzymatic production of UDCA employing Rt7ß-HSDHM3 decreased by 22% in contrast to that of Rt7ß-HSDHM0, indicating the tremendous potential of the variant Rt7ß-HSDHM3 for more efficient and economic production of UDCA.

Inhibitory Effect of Water Extract of Broussonetiae Fructus on Hepatocellular Carcinoma Induced by Diethylnitrosamine in Mice and Effect of PTEN/PI3K/Akt Signaling Pathway / 中国实验方剂学杂志

ObjectiveTo explore the inhibitory effect of water extract of Broussonetiae Fructus on hepatocellular carcinoma （HCC） induced by diethyl nitrosamine （DEN） in mice based on homologous phosphatase and tensin homolog/phosphatidylinositol 3-kinase/protein kinase B （PTEN/PI3K/Akt） signaling pathway. MethodThe primary HCC mouse model was constructed by intraperitoneal injection of DEN solution， and the HCC mice were randomly divided into model group， sorafenib group （0.01 g·kg-1·d-1）， low-dose Broussonetiae Fructus water extract group （0.9 g·kg-1·d-1）， medium-dose Broussonetiae Fructus water extract group （1.8 g·kg-1·d-1）， and high-dose Broussonetiae Fructus water extract group （3.6 g·kg-1·d-1）， with 10 mice in each group. Another 10 C57BL/6 mice were selected as a control group and intraperitoneally injected with an equal volume of normal saline. Mice were treated with different concentrations of Broussonetiae Fructus water extract when liver cancer-like white nodules appeared. sorafenib group was treated with sorafenib. The control group and model group were intraperitoneally injected with normal saline. The activities of alkaline phosphatase （ALP）， aspartate aminotransferase （AST）， alanine aminotransferase （ALT）， and γ-glutamyl transferase （γ-GT） in the serum of mice were detected by the biochemical analyzer. The expression levels of alpha-fetoprotein （AFP） and carcinoembryonic antigen （CEA） were detected by enzyme-linked immunosorbent assay （ELISA）. The degree of hepatocyte canceration and hepatocyte injury were observed by Hematoxylin-eosin （HE） and Masson staining. The proliferation of HCC cells was observed by immunohistochemical staining. The apoptosis of HCC cells in mice was observed by erminal-deoxynucleotidyl transferase mediated nick end labelling （TUNEL） staining. The expression levels of PTEN， PI3K， Akt， and p-Akt proteins related to the PTEN/PI3K/Akt signaling pathway were detected by Western blot. ResultCompared with the control group， the activities of ALP， AST， ALT， and γ-GT， as well as the expression levels of AFP and CEA in the model group were significantly increased （P<0.01）. Carcinogenesis and inflammatory cell infiltration were obvious in liver tissue of mice， and a large number of blue collagen fiber hyperplasia was found. The number of Ki67 positive cells was significantly increased （P<0.01）， and the expression level of PTEN protein was significantly decreased， while PI3K and p-Akt protein expression was increased （P<0.01）. Compared with the model group， the activities of ALP， AST， ALT， and γ-GT， as well as the expression levels of AFP and CEA in the medium-dose and high-dose Broussonetiae Fructus water extract groups were significantly decreased （P<0.05， P<0.01）. The degree of carcinogenesis and inflammatory cell infiltration in liver tissue were reduced， and the collagen fiber hyperplasia was significantly reduced. The number of Ki67 positive cells was significantly decreased， and the number of TUNEL positive apoptotic cells was significantly increased （P<0.05， P<0.01）. PTEN protein expression was increased， while p-Akt protein expression was significantly decreased （P<0.05， P<0.01）. ConclusionThe water extract of Broussonetiae Fructus has a significant inhibitory effect on DEN-induced primary HCC in mice， and its mechanism may be related to the regulation of key protein expressions in the PTEN/PI3K/Akt signaling pathway.

Construction and optimization of a biocatalytic route for the synthesis of neomenthylamine from menthone.

(+)-Neomenthylamine is an important industrial precursor used to synthesize high value-added chemicals. Here, we report a novel biocatalytic route to synthesize (+)-neomenthylamine by amination of readily available (-)-menthone substrate using ω-transaminase. By screening a panel of ω-transaminases, an ω-transaminase from Vibrio fluvialis JS17 was identified with considerable amination activity to (-)-menthone, and then characterization of enzymatic properties was conducted for the enzyme. Under optimized conditions, 10 mM (-)-menthone was transformed in a mild aqueous phase with 4.7 mM product yielded in 24 h. The biocatalytic route using inexpensive starting materials (ketone substrate and amino donor) and mild reaction conditions represents an easy and green approach for (+)-neomenthylamine synthesis. This method underscores the potential of biocatalysts in the synthesis of unnatural terpenoid amine derivatives.

Is the combination of acupuncture and Western medicine superior to monotherapy in the treatment of patients with Alzheimer's disease: A protocol for systematic review and network meta-analysis.

BACKGROUND: Alzheimer disease (AD) is a common cause of dementia, and there are still a lack of treatment options to reverse or prevent disease progression. Existing evidence shows that acupuncture has advantages in the treatment of AD, but whether the efficacy of acupuncture belongs to the placebo effect remains controversial, and there is no strict systematic review and network meta-analysis to evaluate the efficacy and safety of acupuncture combined with Western medicine in the treatment of AD. METHODS: From the inception to February 2023, the Embase, Latin American and Caribbean Health Sciences Literature, Medline, the Cochrane Collaboration's Controlled Clinical Trials, Scopus, China Biomedical Literature Database, Wanfang Database, China National Knowledge Infrastructure, and Australian Medical Index will be searched using the key phrases "acupuncture," "warm needling," "electroacupuncture," "Alzheimer disease," and "cohort" for all relevant studies. Quality assessment of all studies included in this review will be independently assessed by 2 reviewers using the Cochrane Collaborations tool. When significant heterogeneity is indicated, we will find the source of heterogeneity by subgroup or sensitivity analysis. DISCUSSION: This study will evaluate the efficacy of acupuncture combined with Western medicine in improving cognitive function and activities of daily living in AD patients. The results of this study will verify whether the efficacy of acupuncture in the treatment of AD belongs to the placebo effect, which will also provide a reference for the clinical use of acupuncture combined with Western medicine in the treatment of AD.

Single ultrasound-guided thoracic paravertebral block with a large volume of anesthetic for microwave ablation of lung tumors.

Objective: To compare single ultrasound-guided thoracic paravertebral block (TPVB) using a large volume of anesthetic with local anesthesia (LA) in computed tomography (CT)-guided pulmonary microwave ablation. Subjects and methods: Eighty patients who underwent CT-guided microwave ablation of pulmonary tumors were randomly divided into the TPVB group and the LA group. Patients of the TPVB group were anesthetized with a single injection of a large volume (40 ml) of 0.375% ropivacaine injection at T4, and those of the LA group had local infiltration by the surgeon at the puncture site, and emergency rescue with propofol injection was administered when the patient could not tolerate pain in either group. The following variables were recorded in both groups: general conditions; volume of propofol injection for emergency rescue during ablation; visual analog scale (VAS) scores during ablation and at 0, 2, 12, and 24 h after ablation; the need to use analgesics for rescue within 24 h after ablation; number of ablations; number of punctures performed by the surgeon; patient's movements during puncturing; and puncturing-associated complications. Results: Compared with the TPVB group, the amount of emergency use of propofol injection was significantly more in the LA group (P < 0.05). There were no significant differences in the VAS scores recorded intraoperatively and at 0, 2, 12, and 24 h after ablation between the two groups (P > 0.05). There was a significant difference in the patient's movements upon puncturing between the two groups (P < 0.05), but there were no significant differences in the numbers of punctures and ablations between the two groups (P > 0.05). The number of patients using analgesics within 24 h after the operation was also more in the LA group than in the TPVB group, and the difference between the two groups was statistically significant (P < 0.05). Conclusion: Single ultrasound-guided TPVB with a large volume of anesthetic offers effective analgesia for microwave ablation of lung tumors, helping the patient cooperate with the operating surgeon to reduce injury from multiple lung punctures. Further studies are recommended to validate these findings.

Spin Effect to Promote Reaction Kinetics and Overall Performance of Lithium-Sulfur Batteries under External Magnetic Field.

Lithium-sulfur batteries (LSBs) are still limited by the shuttle of lithium polysulfides (LiPS) and the slow Li-S reaction. Herein, we demonstrate that when using cobalt sulfide as a catalytic additive, an external magnetic field generated by a permanent magnet can significantly improve the LiPS adsorption ability and the Li-S reaction kinetics. More specifically, the results show both experimentally and theoretically how an electron spin polarization of Co ions reduces electron repulsion and enhances the degree of orbital hybridization, thus resulting in LSBs with unprecedented performance and stability. Under an external magnetic field, LSBs with 0.0084 % per cycle decay rate at 2 C during 8150 cycles are produced. Overall, this work not only demonstrates an effective strategy to promote LiPS adsorption and electrochemical conversion in LSBs at no additional energy cost but also enriches the application of the spin effect in the electrocatalysis fields.

Myostatin inhibits insulin-like growth factor 1-dependent citrate secretion and osteogenesis via nicotinamide adenine dinucleotide phosphate oxidase-4 in a mouse mesenchymal stem cell line.

Citrate is an indispensable component of bone. Reduced levels of citrate in bone and serum are reported in the elderly and in osteoporosis patients. Myostatin (Mstn) is implicated in skeletal homeostasis, but its effects on osteogenesis remain incompletely understood. Nox4 has critical roles in bone homeostasis. TGF-ß/Mstn-associated Smad2/3 signaling has been linked to Nox4 expression. Insulin-like growth factor (IGF-1) has been shown to counteract many regulatory effects of Mstn. However, the crosstalk among Mstn, IGF-1, and Nox4 is not well understood; the interactive effects of those factors on citrate secretion, osteogenic differentiation, and bone remodeling remain unclear. In this study, we demonstrated that osteogenic differentiation induced an IGF-1-dependent upregulation of citrate secretion that was suppressed by Mstn. Inhibition of Nox4 prevented Mstn-induced reduction of citrate secretion. In addition, Mstn reduced bone nodule formation; these changes were prevented by Nox4 inhibition. Moreover, Mstn increased the ratio of RANKL to OPG mRNAs to favor osteoclast activation. These results indicate that Mstn negatively regulates osteogenesis by increasing levels of Nox4, which reduced IGF-1 expression, citrate secretion, and bone mineralization while also altering the RANKL to OPG ratio. These findings provide new and highly relevant insights into the osseous effects of myostatin.

Transcriptomic Profiling of Electroacupuncture Regulating the Molecular Network in Hippocampus of Rats with Cerebral Ischemia-Reperfusion Injury.

Objective: To explore the mechanism of electroacupuncture stimulation of the hand-taiyin meridian in regulating the molecular network of rats with cerebral ischemia-reperfusion injury based on transcriptomics. Methods: Male SD rats were randomly divided into sham operation group, model group, and electroacupuncture (EA) group. Middle cerebral artery embolization/reperfusion injury (MCAO/R) was used to establish the model group and EA group. The sham operation group only performed sham operation without modeling and any intervention, and the model group was bound daily. The EA group received electroacupuncture to stimulate the acupoints of hand-taiyin meridian for 14 days. Then, neurological scores, pathomorphological observations, and Tunel staining were performed. Finally, the affected hippocampus of the rat was used for transcriptome sequencing and RT-PCR detection. Results: After electroacupuncture intervention in rats, neurological function scores were improved, and neuronal apoptosis was reduced. The results of transcriptomics showed that a total of 1097 differentially expressed genes were obtained, of which 422 were upregulated and 675 were downregulated. The bioinformatics analysis showed that those differentially expressed genes were related to axon development, neuron projection development, neuron projection morphogenesis, plasma membrane cell projection morphogenesis, cell part morphogenesis, notch signaling pathway, long-term potentiation, MAPK signaling pathway, Hedgehog signaling pathway, and so on. The results of RT-PCR showed that Caspase 9 mRNA increased and BDNF, Grin2a, and PlexinD1 mRNA decreased after electroacupuncture intervention (P < 0.05). Conclusion: Electroacupuncture intervention on hand-taiyin meridian may reduce neurological function scores, inhibit neuron apoptosis, and enhance neuronal repair neuroreparation in MCAO/R rats, which may be related to the regulation of genes such as Caspase 9, BDNF, Grin2a, and PlexinD1.

Building Flexible Escherichia coli Modules for Bifunctionalizing n-Octanol: The Byproduct of Oleic Acid Biorefinery.

Artificial biorefinery of oleic acid into 1,10-decanedioic acid represents a revolutionizing route to the sustainable production of chemically difficult-to-make bifunctional chemicals. However, the carbon atom economy is extremely low (56%) due to the formation of unifunctional n-octanol. Here, we report a panel of recombinant Escherichia coli modules for diverse bifunctionalization, where the desired genetic parts are well distributed into different modules that can be flexibly combined in a plug-and-play manner. The designed ω-functionalizing modules could achieve ω-hydroxylation, consecutive ω-oxidation, or ω-amination of n-octanoic acid. By integrating these advanced modules with the reported oleic acid-cleaving modules, high-value C8 and C10 products, including ω-hydroxy acid, ω-amino acid, and α,ω-dicarboxylic acid, were produced with 100% carbon atom economy. These ω-functionalizing modules enabled the complete use of all of the carbon atoms from oleic acid (released from plant oil) for the green synthesis of structurally diverse bifunctional chemicals.

Metal Ion Cutting-Assisted Synthesis of Defect-Rich MoS2 Nanosheets for High-Rate and Ultrastable Li2S Catalytic Deposition.

Active metal ions often show a strong cutting effect on the chemical bonds during high-temperature thermal processes. Herein, a one-pot metal ion cutting-assisted method was adopted to design defect-rich MoS2-x nanosheet (NS)/ZnS nanoparticle (NP) heterojunction composites on carbon nanofiber skeletons (CNF@MoS2-x/ZnS) via a simple Ar-ambience annealing. Results show that Zn2+ ions capture S2- ions from MoS2 and form into ZnS NPs, and the MoS2 NSs lose S2- ions and become MoS2-x ones. As sulfur hosts for lithium-sulfur batteries (LSBs), the CNF@MoS2-x/ZnS-S cathodes deliver a high reversible capacity of 1233 mA h g-1 at 0.1 C and keep 944 mA h g-1 at 3 C. Moreover, the cathodes also show an extremely low decay rate of 0.012% for 900 cycles at 2 C. Series of analysis indicate that the MoS2-x NSs significantly improve the chemisorption and catalyze the kinetic process of redox reactions of lithium polysulfides, and the heterojunctions between MoS2-x NSs and ZnS NPs further accelerate the transport of electrons and the diffusion of Li+ ions. Besides, the CNF@MoS2-x/ZnS-S LSBs also show an ultralow self-discharge rate of 1.1% in voltage. This research would give some new insights for the design of defect-rich electrode materials for high-performance energy storage devices.

Carving the Active Site of CYP153A7 Monooxygenase for Improving Terminal Hydroxylation of Medium-Chain Fatty Acids.

The P450-mediated terminal hydroxylation of non-activated C-H bonds is a chemically challenging reaction. CYP153A7 monooxygenase, discovered in Sphingomonas sp. HXN200, belongs to the CYP153A subfamily and shows a pronounced terminal selectivity. Herein, we report the significantly improved terminal hydroxylation activity of CYP153A7 by redesign of the substrate binding pocket based on molecular docking of CYP153A7-C8:0 and sequence alignments. Some of the resultant single mutants were advantageous over the wild-type enzyme with higher reaction rates, achieving a complete conversion of n-octanoic acid (C8:0, 1 mM) in a shorter time period. Especially, a single-mutation variant, D258E, showed 3.8-fold higher catalytic efficiency than the wild type toward the terminal hydroxylation of medium-chain fatty acid C8:0 to the high value-added product 8-hydroxyoctanoic acid.

An ultra-low background alpha detection system with a Micromegas-based time projection chamber.

In this paper, a time projection chamber (TPC) system for α radiation detection with ultra-low background is presented, which is based on Micromegas, a type of micro-pattern gaseous detector. Based on multi-dimensional information acquired by the TPC, such as the features of particle energy deposition and 3D track, the system can achieve the purpose of α identification with ultra-low background. A prototype TPC with the volume of 15 × 15 × 6.5 cm3 was developed. It was filled with a gas mixture of 95% neon and 5% isobutene at about 1 bar, and no additional shielding or control of alpha-emitting materials was employed. A low-noise high-integration electronic system based on multi-channel waveform sampling techniques was adopted to read out the anode strip signals. A test with a 241Am α source (5.5 MeV), a 49-h background test, and several other tests with weak radioactive samples in the laboratory environment were conducted. A feature selection method was designed to maximize the suppression of background events while retaining the events of interest. Test results showed that within an assumed 5 × 5 cm2 effective area in the center region of the TPC window, the background count rate of this system was lower than 1.6 × 10-3 counts per minute at 95% confidence level, while retaining the acceptance rate of about 96% for 241Am α particles.

Construction of all-carbon micro/nanoscale interconnected sulfur host for high-rate and ultra-stable lithium-sulfur batteries: Role of oxygen-containing functional groups.

Carbon nanotubes (CNTs) are often used to settle down the sluggish reaction kinetics in lithium-sulfur batteries (LSBs). However, the self-aggregation of CNTs often makes them fail to effectively inhibit the shuttling effect of soluble lithium polysulfide (LiPS) intermediates. Herein, a type of ultra-stable carbon micro/nano-scale interconnected "carbon cages" has been designed by incorporating polar acid-treated carbon fibers (ACF) into three-dimensional (3D) CNT frameworks during vacuum filtration processes. Results show that the ACF-CNT composite frameworks possess a reinforced-concrete-like structure, in which the ACFs can well work as the main mechanical supporting frames for the composite electrodes, and the oxygen-containing functional groups (OFGs) formed on them as cross linker between ACFs and CNTs. Benefitted from this design, the ACF-CNT/S cathodes deliver an excellent rate capability (retain 72.6% at 4C). More impressively, the ACF-CNT/S cathodes also show an ultrahigh cycling stability (capacity decay rate of 0.001% per cycle over 350 cycles at 2C). And further optimization suggests that the suitable treatment on CFs could balance the chemical adsorption (OFGs) and physical confinement (carbon cages), leading to fast and durable electrochemical reaction dynamics. In addition, the assembled soft-pack LSBs further show a high dynamic bending stability.

Regiospecific C-H amination of (-)-limonene into (-)-perillamine by multi-enzymatic cascade reactions.

BACKGROUND: (-)-Limonene, one of cyclic monoterpenes, is an important renewable compound used widely as a key building block for the synthesis of new biologically active molecules and fine chemicals. (-)-Perillamine, as derived from (-)-limonene, is a highly useful synthon for constructing more complicated and functionally relevant chemicals. AIM: We aimed to report a more sustainable and more efficient method for the regiospecific C-H amination of (-)-limonene into (-)-perillamine. RESULTS: Here, we report an artificial penta-enzymatic cascade system for the transformation of the cheap and easily available (-)-limonene into (-)-perillamine for the first time. This system is composed of cytochrome P450 monooxygenase, alcohol dehydrogenase and w-transaminase for the main reactions, as well as formate dehydrogenase and NADH oxidase for cofactor recycling. After optimization of the multi-enzymatic cascade system, 10 mM (-)-limonene was smoothly converted into 5.4 mM (-)-perillamine in a one-pot two-step biotransformation, indicating the feasibility of multi-enzymatic C7-regiospecific amination of the inert C-H bond of (-)-limonene. This method represents a concise and efficient route for the biocatalytic synthesis of derivatives from similar natural products.