超高韧性水泥基复合材料研究综述

超高韧性水泥基复合材料具有微裂缝和自愈合特性,以及良好的抗疲劳性、抗渗透性、抗冻融性、抗侵蚀性等性能,具有广阔的工程应用前景。本文主要概述了ECC材料在设计原理、组分选择、基本性能及工程应用方面的研究进展,最后结合其优良特性分析了其在工程应用中的前景。

Increasing fidelity and efficiency by modifying cytidine base-editing systems in rice

The efficiency of plant cytidine base-editing systems is limited, and unwanted mutations frequently occur in transgenic plants. We increased the cytidine editing frequency and fidelity of the plant base editor 3(BE3) and targeted activation-induced cytidine deaminase(CDA)(target-AID) systems by coexpressing three copies of free uracil–DNA glycosylase(UDG) inhibitor(UGI). The editing efficiency of the improved BE3 and CDA systems reached as high as 88.9% and 85.7%, respectively, in regenerated rice plants, with a very low frequency of unwanted mutations. The low editing frequency of the BE3 system in the GC context could be overcome by the modified CDA system. These results provide a highfidelity and high-efficiency solution for rice genomic base editing.

Comparisons between CRM and CCM PFC

The paper presents detailed comparisons between CRM (critical conduction mode) and CCM (continuous conduction mode) control schemes used for Boost PFC converter. The two schemes are analyzed and compared under the chips of L6561 and UC 3854 which are commonly used for CRM and CCM respectively. Both schemes are based on multiplier;however, the CCM is more complex and needs more periphery components which increase the cost. The Boost PFC under CRM is easier to be implemented. Nevertheless, the variable switch frequency makes the system (including the power-stage inductor and capacitor) hard to design. It seems that the CRM PFC is more attractive in low power applications which only need to meet IEC61000-3-2 D standard. Some experiment results are also presented for the comparison.

胶粉改性沥青及胶粉改性方法概述

目前学者对活化胶粉改性沥青的研究刚刚起步,对胶粉的活化方式研究较少。本文从橡胶改性沥青研究现状出发,分析了橡胶改性沥青中胶粉活化的意义;探讨了胶粉活化的机理;总结分析了目前胶粉活化的各种方法。本文目的在于总结就活化胶粉改性沥青的发展现状,以供后期寻找合适的胶粉活化方法,就这一领域进行深入探究。

冻融盐蚀作用对混凝土耐久性影响研究进展

冻融盐蚀作用对混凝土耐久性的劣化作用具有普遍性和直接性。本文总结国内外关于混凝土冻融侵蚀与盐蚀条件下耐久性劣化研究成果,阐述目前混凝土冻融盐蚀劣化研究领域存在的问题,提出该领域待研究的方向及方法。

喷射混凝土应用及其渗透性、孔结构和力学性能研究

喷射混凝土在我国建设工程中起到越来越重要的作用,本文在国内外研究的基础上,加大了对喷射混凝土性能的研究力度,对喷射混凝土渗透性(透气性、透水性和氯离子迁移)、孔结构(砂浆孔结构和表面孔结构)、力学性能(抗压强度和劈裂抗拉强度)以及作用机理等方面进行探究,研究喷射混凝土配合比对喷射混凝土性能的影响以及三者之间的相互关系,并且介绍了其在施工时需注意的问题及采取的对策措施。

Cerebrovascular hemodynamics in patients with cerebral arteriosclerosis

The present study observed hemodynamic changes in 26 patients with cerebral arteriosclerosis using a cerebral circulation dynamics detector and transcranial Doppler. In patients with cerebral arteriosclerosis the blood supply and flow rate in the bilateral carotid arteries and the blood flow rate in the anterior cerebral and middle cerebral arteries were similar to normal controls, but the cerebral vascular resistance, critical pressure and pulsatility index were increased, and cerebral arterial elasticity and cerebral blood flow autoregulation were decreased. Compared with the lesioned hemisphere of patients with cerebral infarction, the total blood supply and blood flow rate of patients with cerebral arteriosclerosis were higher. Compared with normal subjects, patients with cerebral arteriosclerosis exhibited cognitive disturbances, mainly in short-term memory, attention, abstract capability, and spatial and executive dysfunction. Results showed that cerebral arteriosclerosis does not directly affect the blood supply of a cerebral hemisphere, but affects cognitive function. The increased cerebral vascular resistance and reduced autoregulation of cerebral blood vessels may be important hemodynamic mechanisms of arteriosclerosis-induced cerebral infarction.

胶粉改性沥青及橡胶粉改性方法概述

目前学者对活化胶粉改性沥青的研究刚刚起步,对胶粉的改性方式研究较少。本文从橡胶改性沥青研究现状出发,通过分析橡胶改性沥青中胶粉活化的意义;探讨了胶粉活化的机理;总结分析了目前胶粉改性的方法。本文目的在于总结就活化胶粉改性沥青的发展现状,以供后期寻找合适的胶粉活化方法,就这一领域进行深入探究。

Analysis and Modeling of Buck Converter in Discontinuous-Output-Inductor-Current Mode Operation

The Buck converter with LC input filter operating in discontinuous output current mode has a high power factor with a constant duty cycle. A Buck converter in this operation mode can reduce the reverse recovery loss of the freewheeling diode thus increase the efficiency. The operation, power factor analysis and modeling of the converter are studied in this paper. Experimental results are presented to verify the theoretical predictions.

A High Power Factor Rectifier Based on Buck Converter Operating in Discontinuous Inductor Current Mode

By adding a suitable LC filter to the input of a Buck converter, a high-power-factor buck converter is proposed. The converter can operate in the discontinuous-output-current mode operation. A Buck converter in this operation mode features simple control as the constant duty cycle PWM used. The operation condition of the converter is studied. The validity of analysis is verified by Simulation and Experimental results.

A Single Phase Current Source PFC Converter Based on UC3854

A novel high-power-factor Buck type converter with average current control based on UC 3854 is proposed. The input current is directly controlled by average current control scheme to deliver sinusoidal input current and to gain a high power factor. The practical results, which illustrate the proposed control philosophy, were obtained from a 120 W AC/DC Buck type converter. The power factor can reach 0.97.

Study on the Theory and Method of Real Estate Property Right Appraisal

This paper first introduces the overview of real estate appraisal theory,the basic situation of real estate appraisal,the basic principles and characteristics of real estate appraisal,and three main appraisal methods.On this basis,the specific use scope of each method,the meaning of each parameter,and the influencing factors are analyzed.Then,based on the in-depth study of various existing appraisal theories and methods,a new appraisal method is proposed:the appraisal analysis method based on fuzzy analytic hierarchy process.

Novel Strategies for Redirecting NK Cells in Cancer Immunotherapy

Natural killer(NK)cells act as a first line of defense in innate immune system against new malignant transformed cells without prior exposure to tumor antigens.The activity of NK cells is tightly controlled by a balance between inhibitory receptors and activating receptors,and when activation signals outweigh inhibitory signals,NK cells can mediate a response to eliminate the targeted cells.As a bridge between the innate and adaptive immune responses to enhance destruction of tumors,NK cells kill their tumor targets through a variety of mechanisms,including receptor-mediated cytotoxicity,antibody-dependent cell-mediated cytotoxicity(ADCC),death receptor Fas/FasL signaling pathway-mediated cancer apoptosis.However,the efficacy of using NK cells for tumor immunotherapy has been limited by a lack of antigen specificity.To overcome this limitation,Vallera and colleagues developed a bispecific killer cell engager(BiKE),which is comprised of a first ScFv that recognizes a tumor antigen and a second ScFv against CD16(expressed on NK cells)to trigger ADCC.To overcome the poor expansion of NK cells in vivo,a novel trispecific killer cell engager(TriKE)was evolved from the BiKE by the same team.In this molecule,IL-15 was integrated to promote NK cell expansion,thereby eliciting superior NK cytotoxicity and NK cell persistence in vivo compared to BiKE.In order to simultaneously target drug-refractory cancer stem cells(CSC)and cancer cells,a novel tetraspecific killer engager(TetraKE)comprising anti-CD133,EpCAM,CD16 ScFvs and a sustaining IL-15 signal cross-linker was recently developed.Compared to BiKE or TriKE,TetraKE1615EpCAM133 was highly specific against EpCAM-and CD133-bearing cells,leading to enhanced NK cell proliferation,prolonged survival and a limited cytokine response.This TetraKE represents a promising new modality for immunotherapy.

An epi-allele of SMS causes Sanming dominant genic male sterility in rice

Male sterility is an important trait in rice for hybrid rice(Oryza sativa)breeding.However,the factors involved in dominant male sterility are largely unknown.Here,we identified a gene from Sanming dominant genic male sterile rice,named Sanming dominant male sterility(SMS),and reported that an epi-allele of this locus contributes to male sterility.Segregation analysis attributed dominant male sterility to a single locus,SMS,which we characterized using a male-sterile near isogenic line(NIL)of rice cultivar 93-11.The SMS locus was heterozygous in the male-sterile 93-11 NIL,containing an epi-allele identical to that in 93-11,and an epi-allele identical to that in rice cultivar Nipponbare,which we refer to as SMS9 and SMSN,respectively.SMS9is silent and hyper-methylated,whereas SMSNis expressed and hypo-methylated in the 93-11 NIL.Overexpressing SMSNled to male sterility.Mutations in SMS rescued the male sterility of the 93-11 NIL.Interestingly,we observed the duplication of SMSN in Nipponbare,but did not observe the duplication of SMS9in 93-11.Together,these findings suggest that the reduced methylation and enhanced expression of the SMSNepi-allele in the 93-11 NIL is responsible for its role in conferring dominant male sterility.

Rapid improvement of grain weight via highly efficient CRISPR/Cas9-mediated multiplex genome editing in rice

Most of the important agronomic traits in crop plants, such as yield, quality and stress response, are quantitative and jointly controlled by many genomic loci or major genes. Improving these complex traits depends on the combination of beneficial alleles at the quantitative trait loci （QTLs）. However, the conventional cross breeding method is extremely time-consuming and laborious for pyramiding multiple QTLs. In certain cases, this approach might be technically difficult because of close linkage between genes separately responsible for desirable and undesirable traits.

Three new decarbonyl prenylphloroglucinols bearing unusual spirost subunits from Hypericum scabrum and their neuronal activities

Three novel polycyclic polyprenyled acylphloroglucinols,Hyperscabins A-C,were obtained from the aerial parts of Hypericum scabrum.They featured an unprecedented 5,5-spiro ketal subunit with the loss of C-2’carbonyl in the phloroglucinol ring.Their structures were characterized by extensive spectroscopic analyses,NMR calculations with DP4+analysis,calculated electronic circular dichroism(ECD)spectra and the application of modified Mosher’s methods.In the assay of[^(3)H]-5-HT and[^(3)H]-NE reuptake inhibition,compounds 1 and 2 showed good inhibito ry activity(81.8%and 83.2%)in 10μmol/L.In addition,compound 1 significantly increased cell viability in the experiment of oxygen and glucose deprivation/deoxygenation.

Hydrolyzable tannins from Balanophora polyandra

This study reports an investigation of the chemical constituents of Balanophora polyandra Griff.Fifteen compounds were isolated by column chromatography on silica gel,Toyo-pearl HW-40C,Sephadex LH-20 and by HPLC.Their structures were elucidated as 1,4-di-O galloy-2-O-[(E)-p-coumaroyl]-β-D-glucopyranose(1),1-O-galloyl-β-D-pyranglucose(2),1-p-coumaryl-β-D-pyranglu-cose(3),1-O-(E)-caffeoyl-β-D-pyranglucose(4),1,3-di-O-galloyl-β-D-pyranglucose(5),1,6-di-O-galloyl-β-D-pyranglucose(6),1-O-(E)-caffeoyl-4-O-galloyl-β-D-pyranglucose(7),1-O-(E)-caffeoy1-6-O galloyl-β-D-pyranglucose(8),1-0-(E)-caffeoy1-4,6-di-O-galloyl-β-D-pyranglucose(9),1-O-(E)-caffeoyl-4,6-(S)-HHDP-B-D-pyranglucose(10),1,23,6-tetra-O-galloyl-β-D-pyranglucose(11),4,6-(S)-hexahydroxydi-phenoyl-(α/β)-D-glucose(12),1-O-(E)-caffeoyl-4,6-[1′,1″-3′,3″,4′,4″-tetrahydroxydibenzofurandicar-boxyl)]-β-D glucopyranose(13),flavogallonic acid(14),and phloretin-4′-O-β-D-glucoside(15)on the basis of spectral analysis.Compound 1 was a new hydrolyzable tannin,9 was obtained from this genus for the first time,and compounds 5,6 and 11-14 were isolated from this plant for the first time.