Effectiveness of Dinoprostone and Cook's Balloon for Labor Induction in Primipara Women at Term

Labor induction is commonly used for achieving successful vaginal delivery.This study aimed to compare the effectiveness of dinoprostone and Cook's balloon as labor-inducing agents in primipara women at term.A retrospective cohort study among primipara women was conducted in Hubei Maternity and Child Health Hospital.Basic clinical characteristics were collected.The main outcomes were vaginal delivery rate,cesarean section rate and forceps delivery rate.Obstetric and perinatal outcomes were also compared.Univariate and multivariate analyses were further performed to evaluate the predictors for vaginal delivery within 24 h.A total of 845 eligible primipara women undergoing labor induction were recruited.Of them,141 women were induced with dinoprostone(dinoprostone group,DG),and 704 with Cook's balloon(Cook's balloon group,CG).Groups were homogeneous except more women with premature rupture of membranes in DG,with gestational hypertension in CG(P<0.05).The vaginal delivery rate within 12 h was 1.98%and 16.52%in CG and DG respectively(P=0.0001).Besides,the vaginal delivery rate within 24 h was 37.62%and 52.26%in CG and DG respectively(P=0.0079).DG showed the lower rate of oxytocin augmentation,artificial rupture of membrane and postpartum hemorrhage and the shorter interval from insertion to active labor than CG(P<0.05).Multivariate regression analysis revealed that abortion history,oxytocin augmentation,artificial rupture of membrane,and obstric analgesia were independent predictors for vaginal delivery within 24 h.In conclusion,dinoprostone was more effective than Cook's balloon to induce labor and achieve vaginal birth in the sample of primipara women at term.

肺癌术后患者下肢深静脉血栓的发生率及相关危险因素分析

背景与目的肺癌在恶性肿瘤中的发病率和死亡率居首位,已成为当前研究的热点问题。临床上根据病理类型将肺癌分为小细胞肺癌(small cell lung cancer,SCLC)和非小细胞肺癌(non-small cell lung cancer,NSCLC),其中NSCLC又包括腺癌、鳞癌及其他类型肺癌,占所有肺癌的80%左右;静脉血栓栓塞症(venous thromboembolism,VTE)包括下肢深静脉血栓(deep venous thrombosis,DVT)和肺动脉栓塞(pulmonary embolism,PE),是一种在肺癌患者中有极高的发病率和死亡率的并发症。本研究旨在明确肺癌术后患者下肢DVT的发生率,并揭示下肢DVT发生的危险因素。方法选择天津医科大学总医院肺部肿瘤外科2021年12月-2022年12月收治的83例肺癌手术患者,入院及术后均行下肢静脉彩超检查,以分析肺癌患者术后下肢DVT的发生率;对患者的临床病例资料进行统计分析,探讨肺癌术后DVT发生的危险因素;并同期监测肺癌患者术后第1、3、5天的凝血功能和血小板,以研究其对血栓发生患者的观测价值。结果肺癌术后患者中,发生下肢DVT为25例,发生率为30.1%,肺癌手术患者中Ⅲ期+Ⅳ期及年龄>60岁者术后下肢DVT发生率更高,差异具有统计学意义(P=0.031,P=0.028);肺癌术后血栓患者术后第1、3、5天的D-二聚体均明显高于肺癌术后非血栓患者(P<0.05),而两组纤维蛋白原(fibrinogen,FIB)和血小板间差异无统计学意义(P>0.05)。结论我们中心肺癌术后患者DVT总体发生率为30.1%;术后中晚期、年龄较大患者更易发生DVT;其中,D-二聚体值较高的患者应考虑到VTE事件发生的可能。

Numerical simulation study on multiphase flow pattern of hydrate slurry

The research on the multiphase flow characteristics of hydrate slurry is the key to implementing the risk prevention and control technology of hydrate slurry in deep-water oil and gas mixed transportation system.This paper established a geometric model based on the high-pressure hydrate slurry experimental loop.The model was used to carry out simulation research on the flow characteristics of gas-liquid-solid three-phase flow.The specific research is as follows:Firstly,the effects of factors such as slurry flow velocity,hydrate particle density,hydrate particle size,and hydrate volume fraction on the stratified smooth flow were specifically studied.Orthogonal test obtained particle size has the most influence on the particle concentration distribution.The slurry flow velocity is gradually increased based on stratified smooth flow.Various flow patterns were observed and their characteristics were analyzed.Secondly,increasing the slurry velocity to 2 m/s could achieve the slurry flow pattern of partial hydrate in the pipeline transition from stratified smooth flow to wavy flow.When the flow rate increases to 3 m/s,a violent wave forms throughout the entire loop.Based on wave flow,as the velocity increased to 4 m/s,and the flow pattern changed to slug flow.When the particle concentration was below 10%,the increase of the concentration would aggravate the slug flow trend;if the particle concentration was above 10%,the increase of the concentration would weaken the slug flow trend,the increase of particle density and liquid viscosity would weaken the tendency of slug flow.The relationship between the pressure drop gradients of several different flow patterns is:slug flow>wave flow>stratified smooth flow.

Genomic features of meiotic crossovers in diploid potato

Meiotic recombination plays an important role in genome evolution and crop improvement.Potato(Solanum tuberosum L.)is the most important tuber crop in the world,but research about meiotic recombination in potato is limited.Here,we resequenced 2163 F2 clones derived from five different genetic backgrounds and identified 41945 meiotic crossovers.Some recombination suppression in euchromatin regions was associated with large structural variants.We also detected five shared crossover hotspots.The number of crossovers in each F2 individual from the accession Upotato 1 varied from 9 to 27,with an average of 15.5,78.25%of which were mapped within 5 kb of their presumed location.We show that 57.1%of the crossovers occurred in gene regions,with poly-A/T,poly-AG,AT-rich,and CCN repeats enriched in the crossover intervals.The recombination rate is positively related with gene density,SNP density,Class II transposon,and negatively related with GC density,repeat sequence density and Class I transposon.This study deepens our understanding of meiotic crossovers in potato and provides useful information for diploid potato breeding.

Effect of Al on microstructure and mechanical properties of cast CrCoNi medium-entropy alloy

Cast Cr Co Ni Alx(x=0-1.2) medium-entropy alloys(MEAs) were produced by arc melting and flip cast to investigate the alloying effect of Al addition on the microstructure, phase constituent and mechanical properties. The crystal structure changes from an initial face-centered cubic(FCC) to duplex FCC and body-centered cubic(BCC) and finally a single BCC with increasing Al content. In the duplex region, FCC and BCC phases form under a eutectic reaction in the interdendrite region. In the single BCC region, the dendrites transform to ordered B2 and disordered A2 BCC phases resulting from spinodal decomposition. Corresponding to their phase constituents, yield strength increases accompanied with an elongation reduction with increasing Al addition. A very interesting phenomenon of very weak ordered FCC(001) spots appearing in Al-0.4 alloy was observed, indicating a local ordering of FCC phase. The changes of fracture surfaces after the tensile deformation are also corresponding to the variations in mechanical properties.

肺癌患者入院时下肢深静脉血栓的发生率及相关危险因素分析

背景与目的静脉血栓栓塞症(venous thromboembolism, VTE)是一种公认的在肺癌患者中有较高发病率和死亡率的并发症。本研究目的是明确我们中心肺癌患者入院时下肢深静脉血栓(lower extremity venous thrombosis, LEDVT)的发生率,并揭示其入院时LEDVT发生的危险因素。方法选择天津医科大学总医院肺部肿瘤外科在2017年7月-2017年12月收治的231例肺癌患者,入院时即行双下肢静脉彩超检查,以分析肺癌患者LEDVT的发生率;同时,对肺良性疾病患者入院时LEDVT的发生率进行比较。在肺癌患者中,进一步分析LEDVT发生与其临床特征的关系,寻找LEDVT发生的可能危险因素;同时,亦分析这些患者的血浆D-二聚体(D-Dimmer)、纤维蛋白原(fibrinogen, FIB)、凝血酶时间(thrombin time, TT)、活化部分凝血酶时间(activated partial thrombin time,APTT)、凝血酶原时间(prothrombin time, PT)及血小板(platelet, PLT)之间的差异。结果在231例肺癌患者中,入院时发生LEDVT者12例,其发生率为5.2%(12/231);而77例肺良性疾病患者入院时均未查见LEDVT的发生,提示肺癌患者入院时LEDVT的发生率明显高于肺良性疾病(P<0.05)。在肺癌患者中进一步分析发现,伴有远处转移(包括N3淋巴结转移)的肺癌患者较不伴有转移者更易发生LEDVT(11.29%, 7/62 vs 2.96%, 5/169)(P<0.05)。肺癌LEDVT组患者入院时的D-Dimer的中位值为1,534mg/L(369 mg/L-10,000 mg/L),明显高于非LEDVT组患者(539 mg/L, 126 mg/L-1,000 mg/L)(P<0.05);而FIB、TT、APTT、PT和PLT在两组患者之间无明显统计学差异(P>0.05)。结论我们中心肺癌患者入院时LEDVT总体发生率约为5%,明显高于肺良性疾病患者。入院时伴有远处转移(包括N3淋巴结转移)的肺癌患者更易发生LEDVT,其中,D-Dimer值较高的患者应考虑到VTE事件发生的可能。

A Pilot Study to Evaluate an Internet-Based Cervical Cancer Screening Model Based on Self-Sampling

Background: Community based cervical cancer screening models using self-collection can effectively place the identification of who is positive in the hands of the patient. The key areas we have identified as critical are 1) education, 2) notification of screening opportunities, 3) registration, 4) submission of samples, 5) receiving results with an explanation, and 6) being advised where to receive evaluation and management from qualified healthcare personnel. Methods: Our primary objectives were to create, register, and pilot a website as a public platform for cervical cancer prevention for both city and rural, individual and organizational application. We selected two sites: Shenzhen City in China as the local city (individual participant) site, and Sangzhi County in Hunan Province as the remote (group management) site. The website was reviewable to all of China, but applications for screening and registration were open only to the women from the 2 pilot sites. In the local site, the women would first sign up (obtain a password) to view the website (www.mcareu.com), and then if they desired, they could register for screening using their true name and their state ID. After an offline confirmation of the address, the sampling kit would arrive. Results were available with additional education and guidance for care also on the website. Findings: 120,099 people nationwide visited the website in 27 months by the end of May, 2015, 1148 women from the sites registered at the website and 87.5% enrolled in the pilot trial. 72.3% of those testing positive returned for management. Virtually 100% of the registration/historical information was entered appropriately and 100% of the samples were handled properly. Interpretation: Web-based decision aids help patients through the uncertainties of healthcare. Applied to cervical cancer screening using self-collection, the effectiveness of the model specifically in respect to accessibility, education, registration, data input, and instructions for positive management was clearly demonstrated by this pilot as well as the potential for future diagnostics applicable to self-collection.

肺癌患者静脉血栓栓塞症的发生及其抗凝治疗

目前,肺癌的发病率和死亡率在全世界范围内居首位。静脉血栓栓塞症(venous thromboembolism,VTE)是一种公认的肺癌并发症,也是肺癌患者的主要死因之一。癌症自身因素、患者自身因素以及治疗相关因素都是导致肺癌患者发生VTE的主要原因。肿瘤细胞可产生组织因子(tissue factor, TF)、癌性促凝物质(cancer procoagulant, CP)、炎症因子和细胞因子,从而直接激活凝血;其中TF过度表达是肿瘤患者血栓形成的主要机制之一。2016年美国胸外科医师协会(American College of Chest Physicians, ACCP)发布的第10版肿瘤患者VTE防治指南(AT-10)指出,抗凝治疗是肺癌患者合并VTE的基本治疗措施;其中低分子肝素(low molecular-weight-heparin,LWMH)被认为是首选的抗凝药物,但要注意出血风险。

Characterizations and Analysis of the Mold from Animal Specimens in Shenzhen Museum

Biological specimens play an important role in cultural exchange, science popularization, scientific research and economic window, but the preparation and preservation technology system of biological specimens is relatively unsafe and inefficient. Mold grows seriously on animal specimens, which is not only harmful to human beings’ health and environment, but also is one of the factors that restricts the development of the natural history museums where these specimens are kept. This paper identified the mold species of animal specimens by PCR with ITS primers, bio-micro-scopic observation, sequencing and phylogenetic tree analysis. The results showed the mold of animal specimens mainly belonged to Aspergillus and Neurospora. This study established the foundations of controlling and restoring the mold that infected animal specimens and guided a new methodology of preparation and environmental friendly exhibition for animal specimens.

部分再结晶对NiFeCoCrMn高熵合金显微组织和拉伸性能的影响

为了调控NiFeCoCrMn高熵合金强度和塑性之间的平衡关系,采用传统的热力学加工技术(冷轧和再结晶),通过不同的再结晶退火工艺得到不同程度的位错强化,并对具有不同再结晶比例的合金进行拉伸性能测试。随着再结晶比例的增加,即应变硬化程度的下降,合金的均匀伸长率和加工硬化率显著提高,但屈服强度和抗拉强度降低。尤其在650℃分别退火10 min和15 min时,获得的再结晶比例分别为37%和74%,相应的屈服强度为1003 MPa和742 MPa,均匀伸长率为4%和24%。强化主要来源于含高密度位错的未再结晶组织,而塑性则是由无应变的再结晶晶粒产生。

LncRNA PVT1 promotes ovarian cancer progression by silencing miR-214

Objective: Emerging evidence indicates that long non-coding RNAs(lnc RNAs) are critical in carcinogenesis and progression of ovarian cancer. This study aimed to explore the functions and molecular mechanisms of plasmacytoma variant translocation I(PVT1) in ovarian cancer Methods: PVT1 and miR-214 were detected by qRT-PCR assays in ovarian cancer tissues and cells. The cell proliferation,migration, and invasion abilities were detected by cell functional experiments, respectively. Western blot assay was performed to detect epithelial-mesenchymal transition(EMT) markers. MiR-214 expression regulated by PVT1 was studied by RNA immunoprecipitation(RIP) and chromatin immunoprecipitation(Ch IP) assays.Results: The expression of PVT1 was up-regulated in ovarian cancer tissues and cell lines. Elevated PVT1 expression was associated with advanced stage and indicated poor prognosis for ovarian cancer patients. The knockdown of PVT1 impaired SKOV3 cell proliferation, migration, and invasion in vitro. The promotion of ovarian cancer progression by PVT1 involved in regulation of the epithelial-mesenchymal transition process and PVT1 interaction with EZH2 represses miR-214 expression in ovarian cancer cells.Conclusions: PVT1 plays an important role in ovarian cancer tumorigenesis, which might be as a novel diagnostic marker and therapeutic target for ovarian cancer.

Construction of the Subtracted cDNA Library of Striatal Neurons Treated with Long-term Morphine

Objective To construct a morphine tolerance model in primarily cultured striatal neurons,and screen the differentially expressed genes in this model using suppression subtractive hybridization (SSH).Methods Sbtracted cDNA libraries were constructed using SSH from normal primarily cultured striatal neurons and long-term morphine treated striatal neurons (10-5 mol/L for 72 hours).To check reliability of the cell culture model,RT-PCR was performed to detect the cAMP-responsive element-binding protein (CREB) mRNA expression.The subtracted clones were prescreened by PCR.The clones containing inserted fragments from forward libraries were sequenced and submitted to GenBank for homology analysis.And the expression levels of genes of interest were confirmed by RT-PCR.Results CREB mRNA expression showed a significant increase in morphine treated striatal neurons (62.85±1.98) compared with normal striatal neurons (28.43±1.46,P<0.01).Thirty-six clones containing inserted fragments were randomly chosen for sequence analysis.And the 36 clones showed homology with 19 known genes and 2 novel genes.The expression of 2 novel genes,mitochondrial carrier homolog 1 (Mtch1;96.81±2.04 vs.44.20±1.31,P<0.01) and thymoma viral proto-oncogene 1 (Akt1;122.10±2.17 vs.50.11±2.01,P<0.01),showed a significant increase in morphine-treated striatal neurons compared with normal striatal neurons.Conclusions A reliable differential cDNA library of striatal neurons treated with long-term morphine is constructed.Mtch1 and Akt1 might be the candidate genes for the development of morphine tolerance.

Study of micro-trichome (mict) reveals novel connections between transcriptional regulation of multicellular trichome development and specific metabolism in cucumber

Trichomes that cover the epidermis of aerial plant organs play multiple roles in plant protection.Compared with a unicellular trichome in model plants,the development mechanism of the multicellular trichome is largely unclear.Notably,variations in trichome development are often accompanied by defects in the biosynthesis of cuticle and secondary metabolites;however,major questions about the interactions between developmental differences in trichomes and defects in metabolic pathways remain unanswered.Here,we characterized the glabrous mutant mict/csgl1/cstbh via combined metabolomic and transcriptomic analyses to extend our limited knowledge regarding multicellular trichome development and metabolism in cucumber.Mict was found to be explicitly expressed within trichome cells.Transcriptomic analysis indicated that genes involved in flavonoid and cuticle metabolism are significantly downregulated in mict mutants.Further metabolomic analysis confirmed that flavonoids,lipids,and cuticle compositions are dramatically altered in mict mutants.Additional studies revealed that Mict regulates flavonoid,lipid,and cuticle biosynthesis by likely directly binding to downstream functional genes,such as CsTT4,CsFLS1,CsCER26,and CsMYB36.These findings suggest that specific metabolic pathways(e.g.,flavonoids and cuticle components)are co-regulated by Mict and provide insights into transcriptional regulation mechanisms of multicellular trichome development and its specific metabolism in cucumber.

Versatile GaInO_3-sheet with strain-tunable electronic structure,excellent mechanical flexibility,and an ideal gap for photovoltaics

Due to many remarkable physical and chemical properties, two-dimensional(2D) nanomaterials have become a hot spot in the field of condensed matter physics. In this paper, we have studied the structural, mechanical, and electronic properties of the 2D GaInO_3 system by first-principles method. We find that 2D Ga InO_3 can exist stably at ambient condition. Molecular dynamic simulations show that GaInO_3-sheet has excellent thermal stability and is stable up to1100 K. Electronic structural calculations show that GaInO_3-sheet has a band gap of 1.56 eV, which is close to the ideal band gap of solar cell materials, demonstrating great potential in future photovoltaic application. In addition, strain effect studies show that the GaInO_3-sheet structure always exhibits a direct band gap under biaxial compressive strain, and as the biaxial compressive strain increases, the band gap gradually decreases until it is converted into metal. While biaxial tensile strain can cause the 2D material to transform from a direct band gap semiconductor into an indirect band gap semiconductor,and even to metal. Our research expands the application of the Ga InO_3 system, which may have potential application value in electronic devices and solar energy.

Investigation on synergistic deposition of wax and hydrates in waxy water-in-oil(W/O) flow systems

Elucidating the synergistic effect of wax and hydrates, involving formation, aggregation and deposition,is imperative to the operation and transportation safety for offshore petroleum fields. To understand the characteristics and mechanism of synergistic deposition of wax and hydrates, flow and deposition experiments of systems with different wax contents(0-2.89 wt%), initial flow rates, pressures and temperatures were conducted in a high pressure visual flow loop. According to the flow rate and pressure drop data as well as the visual window observation, four different types of plugging scenarios of waxhydrate coexisting systems with different flow properties and wall deposition state were summarized,including rapid plugging, transition plugging, gradual plugging type I and gradual plugging type II.Compared with the wax-free system after hydrate formation, even with the addition of anti-agglomerant(AA) with the same concentration, wax-hydrate coexisting systems could not reach stable hydrate slurry flow state, indicating that the existence of wax deteriorated the performance of AA. Aside from the influence of wax crystals on hydrate agglomeration, it was found that wax deposition layer would alter the adhesion and bedding of hydrates, resulting in the variation of flow properties and wall deposition state.For low wax content systems(0.75 wt%) where rapid plugging occurred, the synergistic effect between wax and hydrates promoted the formation of wax-hydrate coupling aggregates, resulting in severe local deposition when the coupling aggregates attained critical deposition size and consequently decreasing flow rate, forming a vicious circle of decreasing transportability. Since bedding of coupling aggregates was hindered by the uniformly coated wax deposition layer on pipe wall, gradual plugging rather than rapid plugging occurred in medium wax content systems(1-1.25 wt%), predominately caused by the gradual increment in viscosity of waxy hydrate slurry. For relatively high wax content systems(2.89 wt%), hydrate formation and plugging did not occur, due to the insulation effect of wax deposition layer. A physical model for the synergistic deposition of wax and hydrates was also presented, which was meaningful to the development of a mathematical model for the prediction of blockage formation and risk analysis.

超高效液相色谱-三重四极杆质谱法同时测定面膜中26种禁用物质

建立了超高效液相色谱-三重四极杆质谱法(UPLC-MS/MS)同时分离测定市售面膜中包括喹诺酮类、咪唑类及糖皮质激素等26种禁用成分。样品经饱和氯化钠溶液分散后乙腈提取,并利用亚铁氰化钾和乙酸锌沉淀大分子基质和固相萃取净化后,以0.1%醋酸乙腈-0.1%醋酸水溶液二元梯度洗脱,采用多反应监测进行分析。结果显示,26种化合物在各自浓度范围内线性关系良好,相关系数均不低于0.995,检出限为1~80 ng/g,定量限为4~380 ng/g,平均回收率为86.4%~115.2%。本法简单准确,灵敏度高,可用于市售面膜中禁用物质的定量分析。

Correlation study of serum Lp-PLA2 and NSE levels with nerve injury degree and lipid metabolism change in patients with acute cerebral infarction

Objective:To study the correlation of serum Lp-PLA2 and NSE levels with nerve injury degree and lipid metabolism change in patients with acute cerebral infarction.Methods: Patients diagnosed with acute cerebral infarction in our hospital between March 2014 and October 2016 were selected as the cerebral infarction group of the study, and healthy subjects receiving physical examination during the same period were selected as control group. Serum was collected to determine the levels of Lp-PLA2 and NSE as well as the content of nerve injury molecules and lipid metabolism molecules.Results:Serum Lp-PLA2, NSE, NO, MDA, LPO, 8-OHdG, ox-LDL, LDL-C and ApoB levels of cerebral infarction group were significantly higher than those of control group while HDL-C and ApoA1 content were significantly lower than those of control group;serum NO, MDA, LPO and 8-OHdG content of patients with NSE>Q3 were significantly higher than those of patients with<Q1, Q1-Q2 and Q2-Q3, serum NO, MDA, LPO and 8-OHdG content of patients with Q2-Q3 were significantly higher than those of patients with<Q1 and Q1-Q2, and serum NO, MDA, LPO and 8-OHdG content of patients with Q1-Q2 were significantly higher than those of patients with<Q1;serum ox-LDL, LDL-C and ApoB content of patients with Lp-PLA2>Q3 were significantly higher than those of patients with<Q1, Q1-Q2 and Q2-Q3 while HDL-C and ApoA1 content were significantly lower than those of patients with<Q1, Q1-Q2 and Q2-Q3;serum ox-LDL, LDL-C and ApoB content of patients with Q2-Q3 were significantly higher than those of patients with <Q1 and Q1-Q2 while HDL-C and ApoA1 content were significantly lower than those of patients with<Q1 and Q1-Q2;serum ox-LDL, LDL-C and ApoB content of patients with Q1-Q2 were significantly higher than those of patients with<Q1 while HDL-C and ApoA1 content were significantly lower than those of patients with<Q1.Conclusion: Serum Lp-PLA2 and NSE levels increase significantly in patients with acute cerebral infarction, the increase of Lp-PLA2 is associated with abnormal lipid metabolism, and the increase of NSE is associated with neural oxidative damage.

Respiratory Viruses and Mycoplasma Pneumoniae Surveillance Among Hospitalized Children with Acute Respiratory Infections—Wuhan City,Hubei Province,China,September-November 2023

Summary What is already known about this topic?Acute respiratory infections(ARIs)are a significant contributor to illness and death in children.There has been a notable rise in the occurrence of ARIs and the associated pathogens in China,which has garnered worldwide attention.What is added by this report?This study conducted a retrospective analysis of the clinical characteristics of children with ARIs in Wuhan City from September to November 2023.

On the room-temperature tensile deformation behavior of a cast dual-phase high-entropy alloy CrFeCoNiAl_(0.7)

The microstructure and room-temperature tensile deformation behavior of the cast CrFeCoNiAl0.7 high-entropy alloy(HEA)were studied in details.The cast HEA consisted of a dual-phase structure of 77.3 vol.%face-centered-cubic(FCC)phase plus 22.7 vol.%B2 phase,and exhibited excellent room-temperature tensile properties with a high yield strength of 876 MPa,ultimate tensile strength of 1198 MPa and a relatively large elongation to fracture of~9%.Dislocations gliding in the FCC phase governed the plastic deformation at the early stage of room-temperature tensile,and disordered dislocations were to form dislocation walls as the deformation proceeded.With further increase in strain to a high level,the stacking faults were generated through the dissociation of the geometrically necessary dislocations,serving as the potential heterogeneous nucleation sites for the deformation twins.

Characterization of powder flow properties from micron to nanoscale using FT4 powder rheometer and PT-X powder tester

The rapid development of nanotechnology has led to a need to further understand the physical char-acteristics of nanoparticles.In this paper,the flow characteristics of micro-nano alumina particles with different particle sizes were characterized.The FT4 powder rheometer and the PT-X powder tester were used to measure the compression,friction,and dynamic properties of powders.Powder compressibility increased significantly as the particle size decreased from 27 μm to 30 nm.Pressure distribution in the silo was measured and predicted by Janssen's theory,with errors mostly less than 10%.The basic flow energy and the specific energy of the three powders were 4983,1734,and 244 mJ,and 6.80,11.70,and 6.70 mJ/g,respectively,indicating that there was no linear relationship between the change in flowability and particle size.The dynamic properties of the powders change from particle-dominated to agglomeration-dominated as the particle size decreases.The conclusion is supported by the results of field emission scanning electron microscopy.