Broadband bidirectional Brillouin–Raman random fiber laser with ultra-narrow linewidth

We present a Brillouin–Raman random fiber laser(BRRFL)with full-open linear cavity structure to generate broadband Brillouin frequency comb(BFC)with double Brillouin-frequency-shift spacing.The incorporation of a regeneration portion consisting of an erbium-doped fiber and a single-mode fiber enables the generation of broadband BFC.The dynamics of broadband BFC generation changing with the pump power(EDF and Raman)and Brillouin pump(BP)wavelength are investigated in detail,respectively.Under suitable conditions,the bidirectional BRRFL proposed can produce a flatamplitude BFC with 40.7-nm bandwidth ranging from 1531 nm to 1571.7 nm,and built-in 242-order Brillouin Stokes lines(BSLs)with double Brillouin-frequency-shift spacing.Moreover,the linewidth of single BSL is experimentally measured to be about 2.5 kHz.The broadband bidirectional narrow-linewidth BRRFL has great potential applications in optical communication,optical sensing,spectral measurement,and so on.

Effective anti-inflammatory phenolic compounds from dandelion:identification and mechanistic insights using UHPLC-ESI-MS/MS,fluorescence quenching and anisotropy,molecular docking and dynamics simulation

This novel study identifi es the effective anti-inflammatory phenolic compounds in dandelion and provides mechanistic insights into their interactions with receptor proteins(toll-like receptor 4,TLR4;co-receptor myeloid differentiation protein-2,MD-2)using UHPLC-ESI-MS/MS,lipopolysaccharide(LPS)-stimulated THP-1 cell line,fluorescence quenching and anisotropy,molecular docking(single ligand and multi-ligand docking)and molecular dynamics simulation.A 50%aqueous methanol extract had a greater anti-inflammatory effect and higher chicoric acid content,compared with the 100%water and 100%methanol extracts.Chicoric acid,chlorogenic acid,methylophiopogonone A,caffeic acid,gallic acid monohydrate and 4’-O-demethylbroussonin A had relatively high binding energies and contents in all extracts.Chicoric acid competed with chlorogenic acid,4’-O-demethylbroussonin A and quercetin for MD-2.Among dandelion’s phenolics,chicoric acid most effectively hindered TLR4-MD-2 complex formation,with a quenching constant of 0.62×10^(6) L/mol for MD-2 or TLR4 at 320 K,and binding energies of-6.87 and-5.97 kcal/mol,respectively,for MD-2 and TLR4.

Modulation bandwidth enhancement in monolithic integrated two-section DFB lasers based on the detuned loading effect

Modulation bandwidth enhancement in a directly modulated two-section distributed feedback(TS-DFB)laser based on a detuned loading effect is investigated and experimentally demonstrated.The results show that the 3-dB bandwidth of the TS-DFB laser is increased to 17.6 GHz and that chirp parameter can be reduced to 2.24.Compared to the absence of a detuned loading effect,there is a 4.6 GHz increase and a 2.45 reduction,respectively.After transmitting a 10 Gb/s non-return-to-zero(NRZ)signal through a 5-km fiber,the modulation eye diagram still achieves a large opening.Eight-channel laser arrays with precise wavelength spacing are fabricated.Each TS-DFB laser in the array has side mode suppression ratios(SMSR)>49.093 dB and the maximum wavelength residual<0.316 nm.

Discrimination capacity analysis of FTIR-PCA and EEM-PARAFAC on dandelion tissues extracts

Dandelion root contains triterpenoids,polyphenols and flavonoids,dandelion leaf is rich in polyphenols,flavonoids,flavonoids glycosides,and dandelion flower mainly contains flavonoids,among other substances.These different substance content leads to specific benefits and function effects of each part.Fourier transform infrared spectroscopy,three-dimensional fluorescence spectroscopy and related multivariate statistical methods are widely used to determine sample characteristics,but limited research focuses on the substance difference and characteristics in dandelion tissues.In this paper,Fourier transform infrared spectra-principal component analysis and three-dimensional fluorescence spectroscopy-parallel factor analysis were conveyed to analyze dandelion stem,leaf,root and flower tissue extracts,for determining the substance species and content difference among dandelion tissues and evaluating the discrimination capacity of these analysis methods.The Fourier transform infrared spectroscopy of root was distinct from others,and the two principal component models could distinguish dandelion stem and flower,but failed to differentiate leaf and root;while the excitation and emission matrix showed that stem and flower,leaf and root had similar intensity band distribution but different fluorescence intensity,and the parallel factor analysis results proved that one-and threecomponent models cannot differentiate the tissues of stem and flower,leaf and root,since the fluorescent compounds(polyphenol,flavonoid etc.)structure and content were similar in different tissues.These results indicated that Fourier transform infrared-principal component analysis might be a useful method when various fluorescent compounds exist.

PPV联合抗VEGF治疗增殖性糖尿病性视网膜病变远期疗效的Meta分析

目的:探究玻璃体切除(PPV)术联合或不联合抗VEGF药物治疗增殖性糖尿病性视网膜病变(PDR)的远期疗效。方法:计算机检索PUBMED、EMBASE、Cochrane Central Register of Controlled Trials(CENTRAL)、Web of Science等多个数据库,查找自建库至2020-07-02关于比较PPV术前是否行抗VEGF药物治疗PDR预后效果的临床随机对照试验(RCT),根据文献纳入与排除标准筛选文献,并进行数据提取和质量评价,主要评价指标包括术后视网膜脱离发生率、黄斑中心凹厚度和最佳矫正视力(BCVA)。结果:最终纳入11项(880眼)RCT研究。Meta分析结果显示,术前行抗VEGF治疗的PDR患者PPV术后视网膜脱离发生率明显低于未注射抗VEGF药物患者(RR=0.39,95%CI 0.22~0.71,P=0.002);亚裔和非亚裔患者中,单纯PPV与联合抗VEGF治疗患者PPV术后视网膜脱离发生率均具有显著差异(亚裔:RR=0.20,95%CI 0.05~0.87,P=0.03;非亚裔:RR=0.46,95%CI 0.24~0.89,P=0.02)。术前抗VEGF治疗的PDR患者PPV术后3、6mo黄斑中心凹厚度均低于PPV术前未行抗VEGF治疗的患者(MD=-78.49,95%CI-94.81~-62.17,P<0.00001;MD=-39.62,95%CI-48.44~-30.80,P<0.00001)。术前抗VEGF治疗的PDR患者PPV术后6mo BCVA优于未行抗VEGF治疗的患者(MD=-0.16,95%CI-0.21~-0.10,P<0.00001)。结论:PPV术前行抗VEGF治疗可有效降低PDR患者术后视网膜脱离发生率,缓解术后黄斑水肿,降低黄斑中心凹厚度,并改善视力预后。

Plant growth and their root development after inoculation of arbuscular mycorrhizal fungi in coal mine subsided areas

Coal mining often cause serious land degradation, soil erosion, and desertification affecting growth of the local vegetation, especially the roots. Arbuscular mycorrhizal fungi （AMF） inoculation is considered a potential biotechnological tool for mined soil remediation because mycorrhizal fungi could improve plant growth environment, especially under adverse conditions due to their good symbiosis. A field experiment was conducted to study the ecological effects of AMF （Funneliformis mosseae, Rhizophagus intraradices） on the growth of Amygdalus pedunculata Pall. and their root development in the regenerated mining subsidence sandy land. The reclamation experiment included four treatments： inoculation of Funneliformis mosseae （F.m）, inoculation of Rhizophagus intraradices （R.i）, combined inoculation of F.m and R.i and non-inoculated treatment. Root mycorrhizal colonization, plant height, crown width, soil moisture, root morphology and certain soil properties were assessed. The results showed that AMF improved the shoot and root growth of Amygdalus pedunculata Pall., and significantly increased root colonization after 1 year of inoculation. Available phosphorus content, activities of phosphatase as well as electrical conductivity in soil rhizosphere of all the three inoculation treatments were higher than that of the non-inoculated treatment. AMF increased the quantity of bacteria and fungi in soil rhizosphere compared with the non-inoculated treatment. Our study indicates that revegetation with AMF inoculum could influence plant growth and root development as well as soil properties, suggesting that AMF inoculation can be effective method for further ecological restoration in coal mine subsided areas.

Dynamic monitoring of soil bulk density and infiltration rate during coal mining in sandy land with different vegetation

To investigate the effects of coal mining on soil physical properties,sandy lands with three major vegetation types(Salix psammophila,Populus simonii,and Artemisia ordosica)were investigated by the ring knife method and double-ring infiltrometer.Specifically,variations in soil bulk density and water infiltration rate and the influences of coal mining and vegetation type on the properties during different subsidence stages were studied at the Shendong Bulianta mine.The results showed that,in the period before mining,soil bulk density occurred in the order A.ordosica>P.simonii>S.psammophila,with a negative correlation between the initial infiltration rate and steady infiltration rate being observed.In the period during mining and 3 months after mining,there were no significant differences in soil bulk density and water infiltration rate among vegetation types.At 1 year after mining,the soil bulk density occurred in the order A.ordosica>S.psammophila>P.simonii,having a negative correlation with the steady infiltration rate.The water infiltration depths of the S.psammophila,P.simonii and A.ordosica were 50,60,and 30 cm,respectively.The infiltration characters were simulated by the Kostiakov equations,and the simulated and experimental results were consistent.Linear regression revealed that vegetation types and soil bulk density had significant effects on soil initial infiltration rate during the four study periods,and the infiltration rate of the period 1 year after mining was mainly influenced by the soil bulk density of the period before mining.The results indicated that vegetation types had significant effects on soil bulk density,and that the tree-shrub-grass mode was better than one single plantation for water conversation and vegetation recovery in sandy land subjected to mining.

Applied Anatomic Site Study of Palatal Anchorage Implants Using Cone Beam Computed Tomography

Aim The purpose of this study was to conduct quantitative research on bone height and bone mineral density of palatal implant sites for implantation, and to provide reference sites for safe and stable palatal implants. Methodology Three-dimensional reformatting images were reconstructed by cone beam computed tomography （CBCT） in 34 patients, aged 18 to 35 years, using EZ Implant software. Bone height was measured at 20 sites of interest on the palate. Bone mineral density was measured at the 10 sites with the highest implantation rate, classified using K-mean cluster analysis based on bone height and bone mineral density. Results According to the cluster analysis, 10 sites were classified into three clusters. Significant differences in bone height and bone mineral density were detected between these three clusters （P〈0.05）. The greatest bone height was obtained in cluster 2, followed by cluster 1 and cluster 3. The highest bone mineral density was found in cluster 3, followed by cluster 1 and cluster 2. Conclusion CBCT plays an important role in pre-surgical treatment planning. CBCT is helpful in identifying safe and stable implantation sites for palatal anchorage.

Fatigue characteristics of sand-cast AZ91D magnesium alloy

The fatigue characteristics of the AZ91D-T6 alloy samples taken from engine blocks have been investigated at 20℃ and elevated temperature(150℃).The fatigue strength and cyclic stress amplitude of the alloy significantly decrease with the increase of the test temperature,although cyclic hardening occurs continuously until failure for both temperatures.With the increase of the temperature,the decreased fatigue life of the alloy tested at the same stress amplitude is mainly attributed to the decreased matrix strength and the increased hysteresis energies.Fatigue failure of the engine blocks made of AZ91D-T6 alloy is mainly controlled by casting defects.For the defect-free specimens,the crack initiation behavior is determined by the single-slip(20℃)and by environment-assisted cyclic slip(150℃)during fatigue,respectively.The low-cycle fatigue lives of the alloy can be predicted using the Coffin-Manson relation and Basquin laws,the three-parameter equation and the energy-based concepts,while the high-cycle fatigue lives of the alloy fitted well with the developed long crack life model and MSF life models.

Light olefin production by catalytic co-cracking of Fischer–Tropsch distillate with methanol and the reaction kinetics investigation

Catalytic co-cracking of Fischer–Tropsch(FT) light distillate and methanol combines highly endothermic olefin cracking reaction with exothermic methanol conversion over ZSM-5 catalyst to produce light olefins through a nearly thermoneutral process. The kinetic behavior of co-cracking reactions was investigated by different feed conditions: methanol feed only, olefin feed only and co-feed of methanol with olefins or F–T distillate. The results showed that methanol converted to C2–C6 olefins in first-order parallel reaction at low space time, methylation and oligomerization–cracking prevailed for the co-feed of methanol and C2–C5 olefins, while for C6–C8 olefins,monomolecular cracking was the dominant reaction whether fed alone or co-fed with methanol. For FT distillate and methanol co-feed, alkanes were almost un-reactive, C3–C5 olefins were obtained as main products, accounting for 71 wt% for all products. A comprehensive co-cracking reaction scheme was proposed and the model parameters were estimated by the nonlinear least square method. It was verified by experimental data that the kinetic model was reliable to predict major product distribution for co-cracking of FT distillate with methanol and could be used for further reactor development and process design.

Design of a polarization splitter for an ultra-broadband dual-core photonic crystal fiber

A novel ultra-broadband polarization splitter based on a dual-core photonic crystal fiber(DC-PCF)is designed.The full-vector finite element method and coupled-mode theory are employed to investigate the characteristics of the polarization splitter.According to the numerical results,a graphene-filled layer not only broadens the working bandwidth but also reduces the size of the polarization splitter.Furthermore,the fluorine-doped region and the germanium-doped region can broaden the bandwidth.Also,the 4.78 mm long polarization splitter can achieve an extinction ratio of-98.6 d B at a wavelength of 1550 nm.When extinction ratio is less than-20 d B,the range of the wavelength is 1027 nm-1723 nm with a bandwidth of 696 nm.Overall,the polarization splitter can be applied to all-optical network communication systems in the infrared and near-infrared wavelength range.

克隆杜洛克种公猪及其扩繁后代的生产性能评价

为评估克隆种公猪在生猪产业上的应用价值,进行杜洛克种公猪的克隆及扩繁试验研究。采集2头常规选育的杜洛克种公猪耳组织,建立细胞系、生产重构胚,移植到受体母猪,分娩克隆公猪并调教采精,采集精液并参配纯种杜洛克母猪,统计其生产性能,以同期普通杜洛克公猪及其后代为对照。结果显示:(1)建立了种猪耳组织细胞建系、重构胚生产、胚胎移植等技术体系;(2)移植7头代孕母猪,共产仔39头克隆杜洛克公猪,断奶存活21头,60日龄存活17头,达100 kg体重日龄测定15头,调教采精成功10头,种猪利用率为25.6%(10/39);(3)获得的克隆公猪与同期杜洛克公猪在初生重、断奶重、校正100 kg体重日龄、校正背膘厚等指标上无显著性差异;(4)获得的59头杜洛克克隆公猪后代与同期普通杜洛克公猪后代在初生重、断奶重、校正100 kg体重日龄、校正背膘等指标上无显著性差异,仅在右乳头数指标上,克隆公猪后代(6.34±0.48)显著低于普通公猪后代(6.60±0.66)。结论:建立了种猪克隆快速扩繁技术平台,但常规选育的克隆公猪及其后代生产性能与普通公猪及其后代无显著差异,需要进一步提高选择准确性,同时提高克隆效率及其存活率,才能满足克隆技术应用于终端公猪生产的产业要求。

A multicenter prospective study of next-generation sequencing-based newborn screening for monogenic genetic diseases in China

Background Newborn screening(NBS)is an important and successful public health program that helps improve the long-term clinical outcomes of newborns by providing early diagnosis and treatment of certain inborn diseases.The develop-ment of next-generation sequencing(NGS)technology provides new opportunities to expand current newborn screening methodologies.Methods We designed a a newborn genetic screening(NBGS)panel targeting 135 genes associated with 75 inborn disorders by multiplex PCR combined with NGS.With this panel,a large-scale,multicenter,prospective multidisease analysis was conducted on dried blood spot(DBS)profiles from 21,442 neonates nationwide.Results We presented the positive detection rate and carrier frequency of diseases and related variants in different regions;and 168(0.78%)positive cases were detected.Glucose-6-Phosphate Dehydrogenase deficiency(G6PDD)and phenylketonuria(PKU)had higher prevalence rates,which were significantly different in different regions.The positive detection of G6PD variants was quite common in south China,whereas PAH variants were most commonly identified in north China.In addi-tion,NBGS identified 3 cases with DUOX2 variants and one with SLC25A13 variants,which were normal in conventional NBS,but were confirmed later as abnormal in repeated biochemical testing after recall.Eighty percent of high-frequency gene carriers and 60%of high-frequency variant carriers had obvious regional differences.On the premise that there was no significant difference in birth weight and gestational age,the biochemical indicators of SLC22A5 c.1400C>G and ACADSB c.1165A>G carriers were significantly different from those of non-carriers.Conclusions We demonstrated that NBGS is an effective strategy to identify neonates affected with treatable diseases as a supplement to current NBS methods.Our data also showed that the prevalence of diseases has significant regional charac-teristics,which provides a theoretical basis for screening diseases in different regions.

PDLLA length on anti-breast cancer efficacy of acid-responsive self-assembling mPEG-PDLLA–docetaxel conjugates

Engineering small-molecule drugs into nanoparticulate formulations provides an unprecedented opportunity to improve the performance of traditional chemo drugs,but suffers from poor compatibility between drugs and nanocarriers.Stimuli-responsive mPEG-PDLLA–drug conjugate-based nanomedicines can facilitate the exploitation of beneficial properties of the carrier and enable the practical fabrication of highly efficacious self-assembled nanomedicines.However,the influence of hydrophobic length on the performance of this type of nanomedicine is little known.Here we synthesized two acid-sensitive ketal-linked mPEG-PDLLA–docetaxel prodrugs with different lengths of PDLLA,and engineered them into self-assembled sub-20 nm micellar nanomedicines for breast cancer chemotherapy.We found that the nanomedicine consisting of a mPEG-PDLLA–docetaxel prodrug with the shorter length of PDLLA stood out due to its potent cytotoxicity,deep penetration into multicellular spheroids,and improved in vivo anticancer performance.Additionally,our prodrug-based nanomedicines outperformed the generic formulation of commercial Nanoxel in terms of safety profile,tolerated doses,and tumor suppression.Our findings indicate that the hydrophobic content of a polymeric prodrug nanomedicine plays an important role in the performance of the nanomedicine,and should be instructive for developing polymeric prodrug-based nanomedicines with clinical translational potential.

Strain-controlled fatigue characteristics of a cast Mg-Nd-Zn under peak-aged and over-aged conditions

Strain-controlled fatigue characteristics of peakaged and over-aged Mg_(96.47)Nd_(2.9)Zn_(0.21)magnesium alloys containing 0.42Zr,including stress response,strain resistance,hysteresis loops,strain-life and corresponding lowcycle fatigue life prediction model,were studied.In the peak-aged state(T61:540℃×8 h+200℃×14 h),the alloy shows higher cyclic stress response,but lower ductility than the alloy in the over-aged state(T6_(2):540℃×8 h+200℃×400 h).The yield strength and ultimate tensile strength of the alloy under T6_(1)-and T6_(2)-treated conditions are close.Compared with T6_(1)-treated alloy,the steady stress amplitude occurred in T6_(2)-treated alloy is due to higher ductility and more homogenous deformation.In T6_(1)state,the fatigue cracks in the alloy first initiate along the cracked persistent slip bands and then propagate in the trans-granular mode,while in the T6_(2)state,the fatigue cracks initiate along grain boundaries and then propagate in the inter-granular mode.

Water quality evaluation of Haihe River with fuzzy similarity measure methods

Fuzzy similarity measures, which are used to judge the closeness of two fuzzy sets, are presented to evaluate the water quality of the Haihe River. Based on the membership functions and coefficient of variation as the weights, four fuzzy similarity measures （including Lattice similarity measure, Hamming similarity measure, Euclidean similarity measure and the max-min similarity measure） are used to classify the 299 samples into the proper water quality standard ranks. The results are compared with the traditional distance discriminant methods. The calculation of two traditional distance discriminant methods （both Euclidean distance and absolute value distance） is also based on the use of coefficients of variation as the weights. Without the Lattice similarity measure, for this method loses some information, the correct assignment of samples classified into the same water quality ranks is 75.92% with the other three similarity measures and two distance discriminant methods. This result shows the reliability of the five methods. Only considering the three similarity measures, there were only 1.01% of the samples that did not classify to the same ranks, while the corresponding ratio of the two distance discriminant methods was 5.69%. The results of leave-one-out cross validation show that more than 88% of the samples are classified to the proper ranks, which demonstrates that the similarity measures are suitable to evaluate the water quality of the Haihe River.

Application of next generation sequencing in the screening of monogenic diseases in China,2021:a consensus among Chinese newborn screening experts

Newborn screening(NBS)refers to a maternal and newborn healthcare technology,in which special examinations of congenital and genetic diseases that could seriously impact the health of newborns,are implemented during the neonatal period to provide early diagnosis and treatment[1].With a history of more than 60 years,NBS has advanced greatly due to technological progress resulting in significant improvement in the number of diseases covered by NBS and in screening efficiency[2-7].

Enantiomer-selective Living Polymerization of rac-Phenyl Isocyanide Using Chiral Palladium Catalyst

We report the polymerization of phenyl isocyanides with the chiral palladium（II） initiating system. The resulting polymers with optically active properties were obtained by polymerization of the racemic isocyanide monomer （rac-1）, and enantiomerically unbalanced polymerization of the monomer was found, providing substantial evidence for the enantiomer-selective polymerization of rac- 1 mediated through chiral catalyst. A comparison between the enantiomerically pure monomers, 4-isocyanobenzoyl-L-alanine decyl ester （1 s） and 4-isocyanobenzoyl-D-alanine decyl ester （1 r）, revealed a drastic discrepancy in the reactivity ratio of their homopolymerizations. It turned out that the monomer reactivity ratio of ls was higher than that of lr with chiral ligands. The results clearly demonstrated the inclination for incorporation of the ls enantiomer during the polymerization process and thus resulted in the enantiomer-selective polymerization in this system. The effects of the catalyst chirality on the optically active properties of polymerization were investigated, and it was concluded that the formation of higher-ordered conformation with a handed helicity might be attributed to the chiral induction of chiral palladium（II） catalyst. Moreover, the polymers obtained through the enantiomer-selective polymerization of the enantiomerically pure monomer were with a significant improvement of the optical activity if the chirality of the monomer and the catalyst matched with each other.

Synthesis of Cyclic Polyolefin: Ring-Opening Metathesis Polymerization by Binuclear Vanadium Complexes

Ring-opening metathesis polymerization(ROMP)of norbornene by binuclear vanadium alkylidene in-situ formed from dialkyl complexes was investigated.Higher activities were observed by the binuclear system than mononuclear analogues.Especially the cyclic polymers were obtained and demonstrated.It is proposed that cyclic binuclear vanadium alkylidene was afforded due to the intramolecular chain-transfer reaction.The size of polymer ring could be adjusted by the vanadium catalyst structure and polymerization temperature.Similar results were also observed in the ROMP of cyclopentene.

Chiral Recognition and Resolution Based on Helical Polymers

Helical polymers have attracted a great deal of attention and been extensively investigated due to their various applications.One of the most importa nt applicati ons of helical polymers is chiral recog nition and resolutio n ofe nan tiomersforthe reas on that a pair of e nan tiomers is comm only with differe nt physiological and toxicological behaviors in biological systems.Helical polymers usually prese nt un expected high chiral recogniti on ability to a variety of racemic compo unds.Whatzs more,the chiral recog nition and resolution abilities of the system are depe ndent on the highly ordered helical structures of the helical polymers.This mini review mainly focuses on the recent progress in chiral recognition and resolution based on helical polymers.The synthetic methodology for helical polymers is firstly discussed briefly.Then recent advances of chiral recog nition and resoluti on systems based on helical polymers,especially polyacetylenes and polyisocya nides,are described.We hope this mini review will in spire more in terest in developing helical polymers and en courage further advances in chiral-related disciplines.