Drug adulteration analysis based on complexation with cyclodextrin and metal ions using ion mobility spectrometry

Drug adulteration and contamination are serious threats to human health therefore,their accurate monitoring is very important.Allopurinol(Alp)and theophylline(Thp)are commonly used drugs for the treatment of gout and bronchitis,while their isomers hypoxanthine(Hyt)and theobromine(Thm)have no effect and affect the efficacy of the drug.In this work,the drug isomers of Alp/Hyt and Thp/Thm are simply mixed withα-,β-,γ-cyclodextrin(CD)and metal ions and separated using trapped ion mobility spectrometry-mass spectrometry(TIMS-MS).TIMS-MS results showed that Alp/Hyt and Thp/Thm isomers could interact with CD and metal ions and form corresponding binary or ternary complexes to achieve their TIMS separation.Different metal ions and CDs showed different separation effect for the isomers,among which Alp and Hyt could be successfully distinguished from the complexes of[Alp/Hyt+γ-CD+Cu–H]^(+)with separation resolution(RP–P)of 1.51;whereas Thp and Thm could be baseline separated by[Thp/Thm+γ-CD+Ca–H]^(+)with RP–P of 1.96.Besides,chemical calculations revealed that the complexes were in the inclusion forms,and microscopic interactions were somewhat different,making their mobility separation.Moreover,relative and absolute quantification was investigated with an internal standard to determine the precise isomers content,and good linearity(R^(2)>0.99)was obtained.Finally,the method was applied for the adulteration detection where different drugs and urine were analyzed.In addition,due to the advantages of fast speed,simple operation,high sensitivity,and no chromatographic separation required,the proposed method provides an effective strategy for the drug adulteration detection of isomers.

Flexo-photocatalysis in centrosymmetric semiconductors

The separation of photogenerated electron–hole pairs is vitally important for photocatalysis,which can be effectively promoted by polarization field.However,it only manifests in piezoelectric/pyroelectric/ferroelectric materials that have a non-centrosymmetric structure.Here,we demonstrate that the polarization enhanced photocatalysis(with wide spectra from ultraviolet(UV)light to visible light)can be achieved in centrosymmetric semiconductors,such asδ-MnO_(2) and TiO_(2) nanosheets integrated nanoflowers,by using the strain-gradient-induced flexoelectric polarization that is always overlooked in polarization-enhanced catalysis.Under ultrasonic and illumination excitation,the organic pollutants(methylene blue(MB),etc.)can be effectively degraded within 30 min with excellent stability and repeatability.Compared with photocatalysis,the flexo-photocatalytic performance of above centrosymmetric semiconductors is substantially increased by 85%.Moreover,the factors related to flexo-photocatalysis such as material morphology,mechanical stimuli source,and adsorption are explored to deeply understand the mechanism of flexo-photocatalysis.This work opens up a way for high-performance photocatalysis in centrosymmetric semiconductors.

Vibration-assisted material damage mechanism:From indentation cracks to scratch cracks

Vibration-assisted grinding is one of the most promising technologies for manufacturing optical components due to its efficiency and quality advantages.However,the damage and crack propagation mechanisms of materials in vibration-assisted grinding are not well understood.In order to elucidate the mechanism of abrasive scratching during vibration-assisted grinding,a kinematic model of vibration scratching was developed.The influence of process parameters on the evolution of vibration scratches to indentation or straight scratches is revealed by displacement metrics and velocity metrics.Indentation,scratch and vibration scratch experiments were performed on quartz glass,and the results showed that the vibration scratch cracks are a combination of indentation cracks and scratch cracks.Vibration scratch cracks change from indentation cracks to scratch cracks as the indenter moves from the entrance to the exit of the workpiece or as the vibration frequency changes from high to low.A vertical vibration scratch stress field model is established for the first time,which reveals that the maximum principal stress and tensile stress distribution is the fundamental cause for inducing the transformation of the vibration scratch cracking system.This model provides a theoretical basis for understanding of the mechanism of material damage and crack propagation during vibration-assisted grinding.

A telomere-to-telomere gap-free assembly of soybean genome

Dear Editor,Soybean(Glycine max),one of the world's most important crops,represents an indispensable source of edible oil and protein for both humans and livestock.The first soybean reference genome of the Williams 82 cultivar(Wm82)was assembled using a wholegenome shotgun approach integrated with physical and highdensity genetic maps in 2010(Schmutz et al.,2010).In addition to the first reference genome,de novo genome assemblies have been released recently for dozens of cultivated soybean accessions with the application of long-read sequencing technology(Li et al.,2014;Shen et al.,2018;Liu et al.,2020).Although those assemblies provide valuable resources for functional genomics and molecular breeding,there are still a number of unresolved gaps that impede the exploration of complex genomic regions such as centromeres and telomeres。

Multi-scale simulation model of air system based on cross-dimensional data transmission method

The Secondary Air System(SAS)plays an important role in the safe operation and performance of aeroengines.The traditional 1D-3D coupling method loses information when used for secondary air systems,which affects the calculation accuracy.In this paper,a Cross-dimensional Data Transmission method(CDT)from 3D to 1D is proposed by introducing flow field uniformity into the data transmission.First,a uniformity index was established to quantify the flow field parameter distribution characteristics,and a uniformity index prediction model based on the locally weighted regression method(Lowess)was established to quickly obtain the flow field information.Then,an information selection criterion in 3D to 1D data transmission was established based on the Spearman rank correlation coefficient between the uniformity index and the accuracy of coupling calculation,and the calculation method was automatically determined according to the established criterion.Finally,a modified function was obtained by fitting the ratio of the 3D mass-average parameters to the analytical solution,which are then used to modify the selected parameters at the 1D-3D interface.Taking a typical disk cavity air system as an example,the results show that the calculation accuracy of the CDT method is greatly improved by a relative 53.88%compared with the traditional 1D-3D coupling method.Furthermore,the CDT method achieves a speedup of 2 to 3 orders of magnitude compared to the 3D calculation.

Double-crosslinked PNIPAM-based hydrogel dressings with adjustable adhesion and contractility

Rapid post-wound closure is necessary to avoid wound infection and promote scar-free healing when skin trauma occurs.In this study,new types of hydrogel dressings with adjustable contractility were fabricated based on N-isopropyl acrylamide/sodium alginate/graphene oxide(P/SA/GO).Then,the chitosan(CS)solution was used as a bridging polymer to achieve tissue adhesion to the hydrogel.The results show that the hydrogel based on poly(N-isopropyl acrylamide)(PNIPAM)not only has the ability to self-shrink but also can adjust the rate of shrinkage through near-infrared thermal stimulation.At the same time,high adhesion strength(7.86±1.22 kPa)between the tissue and the dressing is achieved through the introduction of bridging polymers(CS),and the coating area of the bridging polymer can be adjusted to achieve regional adhesion.The mouse total skin defects experiments have shown that sutures-free wound closure in the early stages of wound healing could be obtained by adjusting the material temperature.Besides,the dressings can promote scar-free wound healing by reducing inflammatory cell infiltration and collagen deposition.These results indicate that double-crosslinked PNIPAM-based hydrogel dressings with adjustable adhesion and contractility proposed in this study provide a candidate material for achieving trackless wound healing.

Metabolomics Combined with Network Pharmacology Uncovers Effective Targets of Tao-Hong-Si-Wu Decoction for Its Protection from Sepsis-Associated Acute Lung Injury

Sepsis-induced acute lung injury(ALI)is a leading cause of death among septic complications.Tao-Hong-Si-Wu decoction(TSD),a classical recipe from traditional Chinese medicine used for treating ischemic stroke,has been recently reported to alleviate inflammation and inflammation-stimulated injuries related to the pathology of ALI.Here,we first observed the therapeutic effect of TSD on sepsis-induced ALI.Based on integrated metabolomics and network pharmacology analysis(NPA)techniques,we aim to understand the mechanism of TSD alleviating ALI.TSD’s effects were observed in rats modeled by cecal ligation and puncture(CLP)and rat macrophages stimulated by lipopolysaccharide(LPS).Metabolomics analyses were applied to determine the ingredients in the medicine and key metabolites correlated to the NPA for the prediction of TSD targets.Gene and protein expressions of the key predicted targets were evaluated in the lung tissue and macrophages of septic model rat by quantitative polymerase chain reaction(PCR)and enzyme-linked immunosorbent assays,respectively.TSD improved survival rate and protected against lung injury in CLP rats.Eleven endogenous metabolites were related to TSD’s actions.TSD significantly suppressed IL-6 and TNF-αsecretions and their gene expressions both in the lung tissue of the model rats and in LPS-stimulated macrophages.TSD also restored decreased lung protein expression of VEGFA in septic model rats.Targeted proteins and their affecting metabolites were finally validated in an external test set of rats.This study shows that metabolomics coupled with NPA is a promising approach to explore potential targets of medicine with complex compositions.

Insight into the interaction between trimethoprim and soluble microbial products produced from biological wastewater treatment processes

Soluble microbial products(SMPs),dissolved organic matter excreted by activated sludge,can interact with antibiotics in wastewater and natural water bodies.Interactions between SMPs and antibiotics can influence antibiotic migration,transformation,and toxicity but the mechanisms involved in such interactions are not fully understood.In this study,integrated spectroscopy approaches were used to investigate the mechanisms involved in interactions between SMPs and a representative antibiotic,trimethoprim(TMP),which has a low biodegradation rate and has been detected in wastewater.The results of liquid chromatography-organic carbon detection-organic nitrogen detection indicated that the SMPs used in the study contained 15% biopolymers and 28% humic-like substances(based on the total dissolved organic carbon concentration)so would have contained sites that could interact with TMP.A linear relationship of fluorescent intensities of tryptophan protein-like substances in SMP was observed(R^(2)>0.99),indicating that the fluorescence enhancement between SMP and TMP occurred.Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy indicated that carboxyl,carbonyl,and hydroxyl groups were the main functional groups involved in the interactions.The electrostatic andπ-πinteractions were discovered by the UV-vis spectra and 1H nuclear magnetic resonance spectra.Structural representations of the interactions between representative SMP subcomponents and TMP were calculated using density functional theory,and the results confirmed the conclusions drawn from the 1H nuclear magnetic resonance spectra.The results help characterize SMP–TMP complexes and will help understand antibiotic transformations in wastewater treatment plants and aquatic environments.

LIN28 coordinately promotes nucleolar/ribosomal functions and represses the 2C-like transcriptional program in pluripotent stem cells

LIN28 is an RNA binding protein with important roles in early embryo development,stem cell differentiation/re-programming,tumorigenesis and metabolism.Previous studies have focused mainly on its role in the cytosol where it interacts with Let-7 microRNA precursors or mRNAs,and few have addressed LIN28's role within the nucleus.Here,we show that LIN28 displays dynamic temporal and spatial expression during murine embryo development.Maternal LIN28 expression drops upon exit from the 2-cell stage,and zygotic LIN28 protein is induced at the forming nucleolus during 4-cell to blas-tocyst stage development,to become dominantly expressed in the cytosol after implantation.In cultured pluripotent stem cells(PSCs),loss of LIN28 led to nucleolar stress and activation of a 2-cell/4-cell-like transcriptional program characterized by the expression of endogenous retrovirus genes.Mechanistically,LIN28 binds to small nucleolar RNAs and rRNA to maintain nucleolar integrity,and its loss leads to nucleolar phase separation defects,ribosomal stress and activation of P53 which in turn binds to and activates 2C transcription factor Dux.LIN28 also resides in a complex containing the nucleolar factor Nucleolin(NCL)and the transcrip-tional repressor TRIM28,and LIN28 loss leads to reduced occupancy of the NCL/TRIM28 complex on the Dux and rDNA loci,and thus de-repressed Dux and reduced rRNA expression.Lin28 knockout cells with nucleolar stress are more likely to assume a slowly cycling,translationally inert and anabolically inactive state,which is a part of previously unappreciated 2C-like transcriptional program.These findings elucidate novel roles for nucleolar LIN28 in PSCs,and a new mechanism linking 2C program and nucleolar functions in PSCs and early embryo development.

Ultraflat, broadband, and highly coherent supercontinuum generation in all-solid microstructured optical fibers with all-normal dispersion

High flatness, wide bandwidth, and high-coherence properties of supercontinuum(SC) generation in fibers are crucial in many applications. It is challenging to achieve SC spectra in a combination of the properties, since special dispersion profiles are required, especially when pump pulses with duration over 100 fs are employed. We propose an all-solid microstructured fiber composed only of hexagonal glass elements. The optimized fiber possesses an ultraflat all-normal dispersion profile, covering a wide wavelength interval of approximately 1.55 μm. An SC spectrum spanning from approximately 1030 to 2030 nm(corresponding to nearly one octave) with flatness<3 dB is numerically generated in the fiber with 200 fs pump pulses at 1.55 μm. The results indicate that the broadband ultraflat SC sources can be all-fiber and miniaturized due to commercially achievable 200-fs fiber lasers. Moreover, the SC pulses feature high coherence and a single pulse in the time domain, which can be compressed to 13.9-fs pulses with high quality even for simple linear chirp compensation. The Fourier-limited pulse duration of the spectrum is 3.19 fs, corresponding to only 0.62 optical cycles.

Temperature-dependent evolution of surface charge screening and polarization at ferroelectric surfaces

The polarization and domain behavior on the surface of a ferroelectric material are significantly affected by the screening processes [1-12].Recently,there has been a notable increase in the theoretical calculations and experiments investigating the dynamics of polarization and domain behaviors coexisting in phase transitions of ferroelectric materials.

Piezo-phototronic and pyro-phototronic effects to enhance Cu（In, Ga）Se2 thin film solar cells

Cu（In, Ga）Se2 （CIGS）-based materials have gained remarkable attention for thin-film photovoltaic applications due to their high absorption coefficient, tunable bandgap, compositional tolerance, outstanding stabilities, and high efficiency. A small increase in the efficiency of CIGS solar cells has huge economic impact and practical importance. As such, we fabricated a flexible CIGS solar cell on a mica substrate and demonstrated the enhanced device performance through the piezo- and pyro-phototronic effects based on a ZnO thin film. The device showed enhanced energy conversion efficiency from 13.48% to 14.23% by decreasing the temperature from 31 to 2℃ at a rate of - 0.6℃·s^-1 via the pyro-phototronic effect, and further enhanced from 14.23% to 14.37% via the piezo-phototronic effect by further applying a static compressive strain. A pyro-electric nanogenerator effect was also found to promote the performance of the CIGS solar cell at the beginning of the cooling process. The manipulated energy band of the CIGS/CdS/ZnO heterojunction under the influence of the inner pyroelectric and piezoelectric potentials is believed to contribute to these phenomena. Applying the piezo- and pyro-phototronic effects simultaneously offers a new opportunity for enhancing the output performance of commercial thin film solar cells.

River Chief System (RCS):An experiment on cross-sectoral coordination of watershed governance

The trans-regional characteristics of watershed governance produce more problems beyond the capacity of each individual water-related department, leading to the fragmentation of watershed management. The River Chief System (RCS) has experienced swift developments over the past decade in China by appointing the local government heads as river chiefs. RCS works efficiently in the short-term due to its superiority in the inclusion of clear responsibility, authority, and multi-sectoral collaboration. However, the characteristics of the authority-based vertical coordination of the hierarchical system remain unchanged, and therefore the problems of organizational logic and the responsibility dilemma still exist. Tasks including perfecting of laws, integrated watershed management, and public participation still need to be completed. RCS reflects the routine and characteristics of the migration of national governance, and as such provides new insights for other developing countries in the design of river management systems.

Pelagic-benthic coupling of the microbial food web modifies nutrient cycles along a cascade-dammed river

Cascade dams disrupt the river continuum,altering hydrology,biodiversity and nutrient flux.Describing the diversity of multi-trophic microbiota and assessing microbial contributions to the ecosystem processes are prerequisites for the restoration of these aquatic systems.This study investigated the microbial food web structure along a cascade-dammed river,paying special attention to the multi-trophic relationships and the potential role of pelagic-benthic coupling in nutrient cycles.Our results revealed the discontinuity in bacterial and eukaryotic community composition,functional group proportion,as well as a-diversity due to fragmentation by damming.The high microbial dissimilarity along the river,with the total multi-trophic P-diversity was 0.84,was almost completely caused by species replacement.Synchronization among trophic levels suggests potential interactions of the pelagic and the benthic groups,of which the p-diversities were primarily influenced by geographic and environmental factors,respectively.Dam-induced environmental variations,especially hydrological and nutrient variables,potentially influence the microbial food web via both top-down and bottom-up forces.We proposed that the cycles of carbon,nitrogen and phosphorus are influenced by multi-trophic groups through autotrophic and heterotrophic processes,predator-prey relationships,as well as the release of nutrients mainly by microfauna.Our results advance the notion that pelagic-benthic trophic coupling may intensify the accumulation of organic carbon,ammonium and inorganic phosphorus,thereby changing the biogeochemical patterns along river systems.As a consequence,researchers should pay more attention to the multi-trophic studies when assessing the environmental impacts,and to provide the necessary guidance for the ecological conservation and restoration of the dam-regulated systems.

Geostrophic current estimation using altimeter data at ground track crossovers in the northwest Pacific Ocean

Geostrophic current comprises a large portion of the ocean current, which plays an important role in global climate change. Based on classic oceanography, geostrophic current can be derived from pressure gradient. Assuming water density to be constant, we can estimate geostrophic current from Absolute Dynamic Topography （ADT）. In this paper, we use ADT data obtained from multi-satellite altimeters to extract sea surface tilts along- track at crossover points. The calculated tilts along these two tracks can be converted into orthogonal directions and are used to estimate geostrophic current. In northwest Pacific, computed geostrophic current velocities are evaluated with Argos data. In total, 771 pairs of temporally and spatially consistent Argos measurements along with estimated geostrophic velocity datasets are used for validation. In this study, the effect of different cut-off wavelengths of the low pass filter applied to ADT is discussed. Our results show that a cut-offwavelength of 75 km is the most suitable choice for the study area. The estimated geostrophic velocity and the Argos measurement are in good agreement with each other, with a correlation coefficient of 0.867 for zonal component, and 0.734 for meridional one. Furthermore, an empirical relationship between the estimated geostrophic velocity and Argos measurement is derived, providing us a favorable and convenient approach to estimate sea surface flow velocity from the geostrophic velocity derived from altimeter data. The experimental application of the derived method on Kuroshio reveals reasonable results compared with previous studies.

Purification and molecular weight distribution of a key exopolysaccharide component of Bacillus megaterium TF10

Extracellular polymeric substances（EPS） are organic metabolic compounds excreted by microorganisms. They largely impact microbial aggregate structures and functions.Extracellular polysaccharides（EP） in EPS are responsible for the formation of microbial aggregates. In this work, we successfully separated and characterized EP from EPS of the bacterium Bacillus megaterium TF10. Extraction of EP from EPS was optimized using Sevag＇s reagent. Chemical characteristics, functional groups, and molecular weight（MW） distribution of EP were compared with the harvested EPS and soluble microbial products（SMP）. We found that the polymers of lower MW and free proteins were successfully removed by Sevag＇s reagent. The higher MW components of EPS were predominantly polysaccharides,while the polymers of lower MW tended to secrete to the supernatant and were described as SMP. A part of the proteins in the EP was polysaccharide-bonded. Our results can be further used in elucidating the complex flocculation mechanisms in which EP play a major role.

Large-mode-area neodymium-doped all-solid double-cladding silicate photonic bandgap fiber with an index step of ～0.5%

A large-mode-area neodymium-doped silicate photonic bandgap fiber was theoretically designed and experimen- tMly demonstrated. The relative index step between the high-index rods and the background glass was -0.5%, which is the lowest cladding index difference reported on rare-earth-doped all-solid photonic bandgap fibers to our knowledge. An output power of 3.6 W with a slope efficiency of 31- was obtained for a 100-cm-long fiber.

The consistency between Na content distribution at the subsurface and the lake body’s movement in Lop Nur

Historically,Lop Nur was a large and famous salt lake that acted as an important geographic position along the ancient‘Silk Road’,and was associated with the surrounding old civilizations,such as Loulan and Haitou.However,it dried up before 1972.It shows a clear‘Ear’feature on synthetic aperture radar(SAR)images.The objective of this paper is to interpret Lop Nur’s environmental evolution during its drying-up process based on an analysis of its sodium sedimentary feature.The genetic algorithm-partial least squares approach is introduced as a modeling method to retrieve the subsurface sodium content from polarimetric parameters obtained by Cloude decomposition.As a result,the R2 and root-mean-square error can reach 0.7 and 9.1 g/kg.It is suggested that the subsurface salt content was the primary reason for the bright-grey strips textures on SAR images.Furthermore,our results show that the sodium content along the same strip changed,with its distribution exhibiting consistency with the lake body’s movement driven by the strong wind.In future,high-precision topographical data will be considered,and should be helpful in the analysis of lake body movement.The method of this paper can also be applied in other similar dried salt lakes.

Approaching the binding between Cu（Ⅱ） and aerobic granules by a modified titration and p-XRF

Interactions between metals and activated sludge can substantially affect the fate and transport of heavy metals in wastewater treatment plants. Therefore, it is important to develop a simple, fast and efficient method to elucidate the interaction. In this study, a modified titration method with a dynamic mode was developed to investigate the binding of Cu（Ⅱ）, a typical heavy metal, onto aerobic granules. The titration results indicated that pH and ionic strength both had a positive effect on the biosorption capacity of the granular sludge. The/-XRF results demonstrated that the distribution of metals on the granular surface was heterogeneous, and Cu showed strong correlations and had the same ＂hot spots＂ positions with other metal ions （e.g., Ca, Mg, Fe etc.）. Ion exchange and complexing were the main mechanisms for the biosorption of Cu（Ⅱ） by aerobic granules. These results would be beneficial for better understanding of Cu（Ⅱ） migration and its fate in wastewater treatment plants.