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Two CHI genes from Chitinolyticbacter meiyuanensis SYBC-H1 encoding chitinases were identified and their protein 3D structures were predicted. According to the amino acid sequence alignment, CHI1 gene encoding 166 aa had a structural domain similar to the GH18 type II chitinase, and CHI2 gene encoding 383 aa had the same catalytic domain as the glycoside hydrolase family 19 chitinase. In this study, CHI2 chitinase were expressed in Escherichia coli BL21 cells, and this protein was purified by ammonium sulfate precipitation, DEAE-cellulose, and Sephadex G-100 chromatography. Optimal activity of CHI2 chitinase occurred at a temperature of 40 °C and a pH of 6.5. The presence of metal ions Fe3+, Fe2+, and Zn2+ inhibited CHI2 chitinase activity, while Na+ and K+ promoted its activity. Furthermore, the presence of EGTA, EDTA, and β-mercaptoethanol significantly increased the stability of CHI2 chitinase. The CHI2 chitinase was active with p-NP-GlcNAc, with the Km and Vm values of 23.0 μmol/L and 9.1 mM/min at a temperature of 37 °C, respectively. Additionally, the CHI2 chitinase was characterized as an N-acetyl glucosaminidase based on the hydrolysate from chitin. Overall, our results demonstrated CHI2 chitinase with remarkable biochemical properties is suitable for bioconversion of chitin waste. [ABSTRACT FROM AUTHOR]

Pollenopyrroside A and capparisine B, two diastereoisomers of pyrrole spiroketal alkaloids isolated from Brassica campestris pollen and Capparis spinosa, were synthesized by an improved microwave-assisted bishydroxymethylation of pyrrole and acid-catalyzed spirocyclization as key steps with total yields of 2.7 and 8.8%, respectively. [ABSTRACT FROM AUTHOR]

We use anhydrous ferric chloride (FeCl3) to intercalate graphite flakes consisting of 2-4 graphene layers and to dope graphene monolayers. The intercalant, staging, stability, and doping of the resulting intercalation compounds (ICs) are characterized by Raman scattering. The G peak of heavily doped monolayer graphene upshifts to ~1627 cm-1. The 2-4 layer ICs have similar upshifts, and a Lorentzian line shape for the 2D band, indicating that each layer behaves as a decoupled heavily doped monolayer. By performing Raman measurements at different excitation energies, we show that, for a given doping level, the 2D peak can be suppressed by Pauli blocking for laser energy below the doping level. Thus, multiwavelength Raman spectroscopy allows a direct measurement of the Fermi level, complementary to that derived by performing measurements at fixed excitation energy significantly higher than the doping level. This allows us to estimate a Fermi level shift of up to ~0.9 eV. These ICs are thus ideal test-beds for the physical and chemical properties of heavily doped graphenes. [ABSTRACT FROM AUTHOR]

Porous poly(vinylidene fluoride) (PVDF) membranes for dehumidification were prepared from a PVDF/dimethylformamide/water system by phase inversion with poly(ethylene glycol) (PEG) as an additive at various concentrations (1.2, 1.8, and 2.4%) and with various molecular weights (1000, 2000, and 6000). The surface morphologies of the resultant membranes were characterized with scanning electron microscopy and atomic force microscopy, and the pore diameter, porosity, and pore size distribution of the membranes were also determined by a gas‐sorption method. The influence of the concentration and molecular weight of PEG on water‐vapor transport through the membranes was evaluated. The moisture‐transport property of the membranes was improved significantly with increases in the concentration and molecular weight of PEG, and a membrane with good moisture permeability was obtained with 2.4% PEG‐6000 as an additive. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [ABSTRACT FROM AUTHOR]

Extradiol dioxygenases facilitate microbial aerobic degradation of catechol and its derivatives by activating molecular dioxygen and incorporating both oxygen atoms into their substrates. Experimental and theoretical studies have focused on the mechanism of the reaction at the active site. However, whether the catalytic rate is limited by O2 access to the active site has not yet been explored. Here, we choose a recently solved X-ray structure of homoprotocatechuate 2,3-dioxygenase as a typical example to determine potential pathways for O2 migration from the solvent into the enzyme center. On the basis of the trajectories of two 10-ns molecular dynamics simulations, implicit ligand sampling was used to calculate the 3D free energy map for O2 inside the protein. The energetically optimal routes for O2 diffusion were identified for each subunit of the homotetrameric protein structure. The O2 tunnels formed because of thermal fluctuations were also characterized by connecting elongated cavities inside the protein. By superimposing the favorable O2 tunnels on to the free energy map, both energetically and geometrically preferred O2 pathways were determined, as also were the amino acids that may be critical for O2 passage along these paths. Our results demonstrate that identical subunits possess quite distinct O2 tunnels. The order of O2 affinity of these tunnels is generally consistent with the order of the catalytic rate of each subunit. As a consequence, the probability of finding the reaction product is highest in the subunit containing the highest O2 affinity pathway. [ABSTRACT FROM AUTHOR]

An electron injection type transparent photosensitive Cu2O/carbon quantum dot (C QD)/ZnO p−n junction film was prepared by a simple route in which, successively, the ZnO film was prepared by a sputtering process, the C QDs and Cu2O were prepared by hydrothermal synthetic and chemical methods, then the C QDs and Cu2O were introduced onto the surface of the ZnO film. The results indicated that the C QDs and Cu2O were well combined with the ZnO film. The transparency and photosensitivity of this film were investigated, and exhibited an obvious photosensitive enhancement compared with those of the unmodified film. Through analysis, this enhancement of the photoconductivity could be attributed to the remarkable Cu2O/ZnO p−n junction and C QDs with unique up-converted photoluminescence. [ABSTRACT FROM AUTHOR]

Condition trend prediction of rolling element bearings play an important role in realtime machinery monitoring and predictive maintenance. In this paper, the authors have presented a method based on wavelet neural network and Local Mean Value Decomposition (LMD) with Singular Value Decomposition (SVD). The rolling bearing vibration signal is decomposed to different nodes by applying the wavelet packet analysis to establish rolling fault band. Based on the feature of spectrum demodulation, a condition trend prediction method is proposed and the accuracy and validity of the prediction model is discussed. [ABSTRACT FROM AUTHOR]

The article presents a research report on an ultrasound-driven immune-boosting molecular machine for systemic tumor suppression. Topics include exploring facile and effective therapeutic modalities for synergistically controlling primary tumor and metastasis remains a pressing clinical need; and Sonodynamic therapy (SDT) offers possibility of noninvasively eradicating local solid tumors, but lacks antimetastatic activity because of its limited ability in generating systemic antitumor effect.

We studied multiexciton dynamics in monolayer WSe2 using nonlinear photoluminescence (PL) spectroscopy and Monte Carlo simulations. We observed strong nonlinear saturation behavior of exciton PL with increasing excitation power density and long-distance exciton diffusion, reaching several micrometers. We demonstrated that the diffusion-assisted exciton-exciton annihilation (EEA) model accounts for the observed nonlinear PL behavior. The long-distance exciton diffusion and subsequent efficient EEA process determined the unusual multiexciton dynamics in atomically thin layered transition metal dichalcogenides. [ABSTRACT FROM AUTHOR]

Background: Fixed-dose combination (FDC) formulations for the treatment of tuberculosis are now being recommended by the World Health Organization and used worldwide for reducing the risk of emerging drug resistance. China also plans that the FDC coverage will be achieved 100% in 2015 in every county in the country. However, the quality of FDCs with respect to variable bioavailability is a major issue. Objectives: This study was conducted in healthy Chinese subjects to compare the bioavailability of rifampicin, isoniazid, ethambutol, and pyrazinamide from a 4-drug FDC formulation versus that of the separate formulations. Methods: The study was designed as randomized, single- dose, 2-treatment, 2-period crossover trial with a washout period of 1 week. Blood samples were collected at 0 (baseline), 10, 20, and 40 minutes and at 1, 1.5, 2, 3, 4, 6, 9, 12, and 24 hours postdose. Plasma concentrations of the 4 drugs were measured by using a rapid chromatography- tandem mass spectrometry method. Pharmacokinetic parameters were calculated by using noncompartmental methods. Bioequivalence was determined if the 90% CIs of the log-transformed test/reference ratios AUC0-24, AUC0-8, and Cmax were within the predetermined range of 80% to 125%. Tolerability was assessed by using clinical parameters and subject reports. Results: A total of 18 male subjects (mean [SD] age, 36.4 [10.6] years) were enrolled and completed the study. In the case of rifampicin, the 90% CIs for the log-transformed ratios of Cmax, AUC0-24, and AUC0-8 were 81.8 to 100.9, 89.5 to 100.2, and 87.1 to 98.0, respectively. For ethambutol, these values were 84.7 to 105.7, 93.5 to 105.1, and 92.1 to 105.4. For pyrazinamide, these values were 83.3 to 93.9, 95.8 to 101.4, and 97.0 to 104.1. For isoniazid, the 90% CIs for the log-transformed ratios of AUC0-24, and AUC08 were 83.5 to 94.6 and 83.4 to 94.4. However, the point estimates for Cmax (62.2-86.7) were outside the limit for bioequivalence. No adverse events were observed during the study. Conclusions: The findings from this single-dose study in healthy Chinese male volunteers suggest that the combined formulation was bioequivalent to separate formulations of rifampicin, ethambutol, and pyrazinamide at the same dose levels. However, isoniazid was not bioequivalent based on Cmax values. Both formulations were well tolerated. Chinese Clinical Trials registration number: ChiCTR-TTRCC-12002451. [ABSTRACT FROM AUTHOR]

Chemistry is a basis for almost all science and engineering disciplines, and needs to be well mastered by both researchers and students. But in the eyes of many Chinese students and their parents, chemistry is not an initial choice because first, it seems to be less important than mathematics and physics, and second, chemistry-majored students usually cannot get high salaries after graduation, and may encounter safety risks when conducting chemical experiments. How can we encourage students in learning chemistry? How can we improve higher chemistry education so that students can truly grasp the basic chemical principles, increase their chemical skills and apply the learnt knowledge in their future careers? Here in this panel discussion, six experts in higher chemistry education try to give their observations and opinions on these issues. Yadong Li President at Anhui Normal University; inorganic chemist. Yan Li Professor at College of Chemistry and Molecular Engineering, Peking University. Jian Pei Professor at College of Chemistry and Molecular Engineering, Peking University. Zhenfeng Xi Professor at College of Chemistry and Molecular Engineering, Peking University. Song Gao (Chair) President at Sun Yat-sen University; inorganic chemist. Lan-Sun Zheng (Chair) Professor at College of Chemistry and Chemical Engineering, Xiamen University., (© The Author(s) 2022. Published by Oxford University Press on behalf of China Science Publishing & Media Ltd.)

Prof. Pinxian Wang () of Tongji University, born in 1936, is one of the leading deep-sea scientists in China. As the first co-chief scientist of Chinese nationality in the international Ocean Drilling Program (ODP), he co-led ODP Leg 184 in 1999; and in 2018, at 82 years old, he dived to a depth of 1400 meters in the South China Sea (SCS) in China's manned submersible 'Deep Sea Warrior'. In recent years, he has also become a star of science popularization in China-he has more than 1.7 million followers on China's video-sharing platform bilibili , and his popular science book Deep Sea in Simple Words is a best seller. In September 2022, Prof. Wang was interviewed by NSR 's Associate Editor-in-Chief, Zhonghe Zhou. In this interview, Prof. Wang summarized his six-decade-long scientific career, talked about the past and future of China's deep-sea research efforts, and explained his opinion on how to promote scientific culture in China., (© The Author(s) 2022. Published by Oxford University Press on behalf of China Science Publishing & Media Ltd.)

On 17 June 2021, China's spacecraft Shenzhou 12 took three Chinese astronauts into the Earth's orbit and docked with the assembly of Tianhe and Tianzhou, the core module and cargo ship of the Chinese Space Station (CSS), which had been launched and assembled in orbit earlier this year. The three astronauts became the first visitors of the CSS and would stay in orbit for about three months. In 2022, two laboratory cabin modules, Wentian and Mengtian, will be launched and assembled into Tianhe, completing the basic structure of the CSS. The CSS is designed to be used for at least 10 years, and will provide an outer space experimental platform for researchers from multiple disciplines. On 23 July 2021, National Science Review ( NSR ) interviewed Professor Ming Gao (), the Commander-in-Chief of the Space Utilizaiton System of the China Manned Space Program, Director General of the Technology and Engineering Center for Space Utilization (CSU) of the Chinese Academy of Sciences and an Academician of the International Academy of Astronautics. The Space Utilizaiton System is the scientific part of the CSS project, responsible for the design and organization of the onboard research programs. Gao has been involved in China's Manned Space Program since 1994, and has experienced the whole development process from the Shenzhou spacecraft to the CSS. In this interview, she introduces the scientific goals, plans and aspirations of the CSS., (© The Author(s) 2021. Published by Oxford University Press on behalf of China Science Publishing & Media Ltd.)

In 1987, several Osaka University researchers discovered a special kind of clustered DNA repeats in bacteria. Within a few years, two other groups independently discovered the same phenomenon but no one knew its function at the time. Only a small handful of scientists studied this property from its discovery in 1987 to 2005. It was then that the function of these DNA repeats, which were named Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR), was finally elucidated. Researchers found that CRISPR, when combined with its CRISPR-associated partner (Cas), is crucial for the functioning of the bacterial adaptive immune system against viral phage infection. CRISPR sequences can be transcribed into targeting RNA molecules, and Cas enzymes are guided by these RNAs to cut specific viral DNA loci, rendering resistance against the viral infection. Scientists realized that this natural bacterial immune response system could be engineered to become a powerful genome editing tool. Prior to CRISPR, existing genome editing tools such as Zinc Finger Nucleases (ZFNs) and Transcription Activator-Like Effector Nucleases (TALENs) relied solely upon protein-DNA interactions to target an enzyme to specific DNA sequences. The design, engineering and evolution of proteins for various DNA sequences is difficult and time-consuming. In contrast, the CRISPR-Cas system uses Watson-Crick base pairing between a guide RNA and the target DNA to localize the complex to specific DNA sequences. This feature enables users to simply change an RNA sequence to match a DNA target to reposition the whole complex. Since then, numerous talented scientists have headed into this field. Within a single decade, they have developed the CRISPR-Cas system into a powerful genome editing tool and applied it to the editing of microorganisms, plants, animals and even human embryos. David R. Liu, Professor of Harvard University and the Broad Institute, and an investigator of the Howard Hughes Medical Institute, is one of them. One of his major contributions to the field is the development of 'base editing'. His group engineered the CRISPR system to transform it from being DNA scissors that cut DNA into specific DNA base pair rewriters that directly convert one base pair to a different base pair. This development opens the door to precision genome editing, raising the possibility of treating thousands of genetic diseases that are caused by single point mutations in the human genome. Here, David talks about this exciting time for genome editing., (© The Author(s) 2018. Published by Oxford University Press on behalf of China Science Publishing & Media Ltd.)