Use of high-resolution X-ray computed tomography and 3D image analysis to quantify mineral dissemination and pore space in oxide copper ore particles

Mineral dissemination and pore space distribution in ore particles are important features that influence heap leaching performance. To quantify the mineral dissemination and pore space distribution of an ore particle, a cylindrical copper oxide ore sample (I center dot 4.6 mm x 5.6 mm) was scanned using high-resolution X-ray computed tomography (HRXCT), a nondestructive imaging technology, at a spatial resolution of 4.85 mu m. Combined with three-dimensional (3D) image analysis techniques, the main mineral phases and pore space were segmented and the volume fraction of each phase was calculated. In addition, the mass fraction of each mineral phase was estimated and the result was validated with that obtained using traditional techniques. Furthermore, the pore phase features, including the pore size distribution, pore surface area, pore fractal dimension, pore centerline, and the pore connectivity, were investigated quantitatively. The pore space analysis results indicate that the pore size distribution closely fits a log-normal distribution and that the pore space morphology is complicated, with a large surface area and low connectivity. This study demonstrates that the combination of HRXCT and 3D image analysis is an effective tool for acquiring 3D mineralogical and pore structural data.

腹内压对胃潴留的影响及其临界值观察

目的通过监测患者腹腔内压变化观察其对胃潴留的影响,寻找胃潴留时的腹内压值,观察胃潴留与急性生理学与慢性健康状况评分系统Ⅱ(APACHE-Ⅱ)评分的相关性。方法选取2014年8月-2016年11月入住该院重症监护病房的患者,留置导尿管、鼻胃管及给予鼻饲能全力液(1 ml:1 kcal,500 ml/瓶1 kcal=4.184kj)。腹内压监测时无使用胃肠动力药物及长期使用镇静药物。用膀胱测压法测腹内压,4次/d,鼻饲后1和12 h后各测2次,每次取平均值。营养方式为鼻胃管微泵加温(37~40℃)鼻饲,第1天速度50 ml/h,如果通畅,第2天及之后为50~100 ml/h,如不畅改为50 ml/h。如果出现胃潴留,即时测腹内压2次,取平均值。潴留后第2天则鼻饲温开水观察何时通畅。对所有患者进行APACHE-Ⅱ评分。结果(1)腹内压平均值为(9.8±1.5)mm Hg。腹腔内高压发生率为64.7%。胃潴留发生率为33.6%。与非腹内高压组比较,腹内高压组胃潴留发生率高(P<0.05);(2)胃潴留时腹内压平均值为(17.4±0.4)mm Hg;(3)胃潴留组与非潴留组APACHE-Ⅱ评分平均值分别为(19.7±3.6)和(12.0±2.5)分,两组比较,胃潴留组的APACHE-Ⅱ评分更高(P<0.05)。结论 ICU中患者腹内压常升高,腹内压升高至(17.4±0.4)mm Hg时鼻胃管鼻饲能全力液患者易出现胃潴留,胃潴留组的APACHE-Ⅱ评分较非胃潴留组高。

Unsaturated flow and solute transport in a porous column using spherical ore particles

This paper dealt with the development of a two-dimensional （2D） mathematical model for column leaching and confirmed the important simulation parameters through experiment. The unsaturated state of the variably saturated flow column and the solute transport of copper ions were studied during leaching. The fluid flow problem was handled using the Richards equation on the premise of an ambient pressure column air, where the van Genuchten formulas were applied to define the nonlinear relationships of pressure head with the retention and permeability properties. The ore column permeability test gave a varied hydraulic conductivity, which was analyzed in the model. In the solute transport problem, the copper ion concentration was solved using the advection-diffusion-reaction equation whose reaction term was determined by the joint analysis of experimental copper leaching rate and the shrinking core model. Particle-and column-scale leaching tests were carried out to illustrate the difference and connection of copper extraction in both processes. This fluid flow and solute transport cou-pled model was determined through the finite element method using the numerical simulation software, COMSOL Multiphysics.

Exploration of nucleos(t)ide analogs cessation in chronic hepatitis B patients with hepatitis B e antigen loss

BACKGROUND Nucleos(t)ide analogs(NAs)cessation in chronic hepatitis B(CHB)patients remains a matter of debate in clinical practice.Current guidelines recommend that patients with hepatitis B e antigen(HBeAg)seroconversion discontinue NAs after relatively long-term consolidation therapy.However,many patients fail to achieve HBeAg seroconversion after the long-term loss of HBeAg,even if hepatitis B surface antigen(HBsAg)loss occurs.It remains unclear whether NAs can be discontinued in this subset of patients.AIM To investigate the outcomes and factors associated with HBeAg-positive CHB patients with HBeAg loss(without hepatitis B e antibody)after cessation of NAs.METHODS We studied patients who discontinued NAs after achieving HBeAg loss.The Cox proportional hazards model was used to identify predictors for virological relapse after cessation of NAs.The cut-off value of the consolidation period was confirmed using receiver operating characteristic curves;we confirmed the cut-off value of HBsAg according to a previous study.The log-rank test was used to compare cumulative relapse rates among groups.We also studied patients with CHB who achieved HBeAg seroconversion and compared their cumulative relapse rates.Propensity score matching analysis(PSM)was used to balance baseline characteristics between the groups.RESULTS We included 83 patients with HBeAg loss.The mean age of these patients was 32.1±9.5 years,and the majority was male(67.5%).Thirty-eight patients relapsed,and the cumulative relapse rate at months 3,6,12,24,36,60,120,and 180 were 22.9%,36.1%,41.0%,43.5%,45.0%,45.0%,45.0%,and 52.8%,respectively.Twentysix(68.4%)patients relapsed in the first 3 mo after NAs cessation,and 35 patients(92.1%)relapsed in the first year after NAs cessation.Consolidation period(≥24 mo vs<24 mo)(HR 0.506,P=0.043)and HBsAg at cessation(≥100 IU/mL vs<100 IU/mL)(HR 14.869,P=0.008)were significant predictors in multivariate Cox regression.In the PSM cohort,which included 144 patients,there were lower cumulative relapse rates in patients with HBeAg seroconversion(P=0.036).CONCLUSION HBeAg-positive CHB patients with HBeAg loss may be able to discontinue NAs therapy after long-term consolidation,especially in patients with HBsAg at cessation<100 IU/mL.Careful monitoring,especially in the early stages after cessation,may ensure a favorable outcome.

Quantum properties of nonclassical states generated by an optomechanical system with catalytic quantum scissors

A scheme is proposed to investigate the non-classical states generated by a quantum scissors device(QSD) operating on the the cavity mode of an optomechanical system. When the catalytic QSD acts on the cavity mode of the optomechanical system, the resulting state contains only the vacuum, single-photon and two-photon states depending upon the coupling parameter of the optomechanical system as well as the transmission coefficients of beam splitters(BSs). Especially, the output state is just a class of multicomponent cat state truncations at time t = 2π by choosing the appropriate value of coupling parameter. We discuss the success probability of such a state and the fidelity between the output state and input state via QSD. Then the linear entropy is used to investigate the entanglement between the two subsystems, finding that QSD operation can enhance their entanglement degree. Furthermore, we also derive the analytical expression of the Wigner function(WF) for the cavity mode via QSD and numerically analyze the WF distribution in phase space at time t =2π. These results show that the high non-classicality of output state can always be achieved by modulating the coupling parameter of the optomechanical system as well as the transmittance of BSs.

Homogenization heat treatment for an additively manufactured precipitation-hardening high-entropy alloy

A precipitation-hardening high-entropy alloy(HEA),(FeCoNi)_(86)Al_(7) Ti_(7),was successfully fabricated using selective laser melting(SLM).Severe segregation of Ti occurred at the boundaries of dislocation cells.Therefore,homogenization heat treatment at 1150℃for 0.5 h was performed to alleviate the microsegregation.After homogenization,almost no dislocation cells were left in the grains,and recrystallization occurred as the average grain size increased from 37 to 54μm.Compared with the initial as-built HEA,the ductility of the HEA increases significantly from 29%to 40%,and the strength decreases slightly from 710 to 606 MPa.For further aging,pre-homogenization can decrease the precipitation of ordered L2_(1) phases.Because void has a high propensity to initiate from the matrix/L2_(1) incoherent interface,pre-homogenization reduced the number of weak points,thus considerably improving the plastic deformation ability of the aged HEA by 36%.In addition,the strengthening mechanism has also been analyzed for the aged HEA.It was revealed that the coherent L1_(2)precipitate contributed the most to the increased strength.