A clinical study on salvage hepatectomy for treating recurrent liver cancer after radiofrequency ablation

Objective We studied the efficacy of salvage hepatectomy for treating recurrent hepatic cancer after radiofrequency ablation （RFA）. Methods A retrospective analysis of 67 patients who had recurrent liver cancer after RFA treatment and received salvage hepatectomy in the Department of Hepatobiliary Surgery, Southwest Hospital, Third Mili- tary Medical University （China）, from January 2006 to January 2014, was performed. The analysis included patient gender, age, hepatitis type, alpha-fetoprotein （AFP）, and TNM stage prior to RFA and salvage hepatectomy, overall survival rates, and tumor-free survival rates after salvage hepatectomy. Results Among the 67 patients, there were 57 cases of hepatitis B, two cases of hepatitis C, and eight cases did not have hepatitis. AFP levels in patients ranged from 3 to 4521 ng/mL （median 33 ng/mL）. Before RFA, 54 cases were stage I tumors, and 13 were stage II tumors. Tumor sizes varied from 0.82 to 4.83 cm （median 3.0 cm）. In 20 cases, one RFA was performed, and for 47 cases, RFA was repeated. RFA- ablated region diameters ranged from 3.8 to 5.2 cm （median 4.5 cm）. The interval between the salvage surgical resection and RFA was 3-37 months. Before salvage hepatectomy, 23 stage I tumors, 12 stage II tumors, and 32 stage III tumors were present （size ranged 4.83-11.84 cm; median 6.3 cm）. For salvage hepatectomy, laparotomy was performed for 56 cases, and laparoscopy was performed for 28 cases. Inflow clamping was performed for 39 cases （15-45 rain）. Surgery was 219-370 rain and intraoperative blood loss was 100-2100 mL. For 13 cases, intraoperative blood transfusion was required. Tumor pathological data revealed 31,35, and 1 poorly, moderately, and well differentiated tumors, respectively. No patients died due to operative complications, and hospital stays were 8-10 days. Overall and tumor-free survival rates were 85% and 79% for 1 year, 50% and 20% for 3 years, and 39% and 19% for 5 years, respectively. Kaplan- Meier analysis and Cox regression confirmed that tumor number and size prior to salvage liver cancer were risk factors affecting survival. Conclusion Patients who received RFA to treat early-stage liver cancer with postoperative recurrent stage I tumors have satisfactory outcomes with salvage hepatectomy.

Microstructural Dependence of Friction and Wear Behavior in Biological Shells

As an essential renewable mineral resource,mollusk shells can be used as handicrafts,building materials,adsor-bents,etc.However,there are few reports on the wear resistance of their structures.The Vicker’s hardness and friction,and wear resistance of different microstructures in mollusk shells were comparatively studied in the pre-sent work.The hardness of prismatic structures is lower than that of cross-lamellar and nacreous structures.How-ever,the experimental results of sliding tests indicate that the prismatic structure exhibits the best anti-wear ability compared with foliated,crossed-lamellar,and nacreous structures.The anti-wear and hardness do not present a positive correlation,as the wear resistance properties of different microstructures in mollusk shells are governed jointly by organic matrix,structural arrangement,and basic building block actions.The present researchfindings are expected to provide fundamental insight into the design of renewable bionic materials with high wear resistance.

The Analytical Expressions for Computing the Minimum Distance between a Point and a Torus

In this paper, we present the analytical expressions for computing the minimum distance between a point and a torus, which is called the orthogonal projection point problem. If the test point is on the outside of the torus and the test point is at the center axis of the torus, we present that the orthogonal projection point set is a circle perpendicular to the center axis of the torus;if not, the analytical expression for the orthogonal projection point problem is also given. Furthermore, if the test point is in the inside of the torus, we also give the corresponding analytical expression for orthogonal projection point for two cases.

Comprehensive investigation on the structural,electronic and mechanical properties of T-Mg_(32)(Al,Zn)_(49)phases in Al-Mg-Zn alloys

In the development process of crossover aluminum alloys,T-Mg_(32)(Al,Zn)_(49)phases play a significant role in the precipitation strengthening effect.However,comprehensive understandings of the structural characteristics,interactions among alloying elements,mechanical property dependence on composition variation,effects of doping and defects etc.are still inadequate.A combination of density functional theory(DFT)calculations and special quasi-random structures(SQSs)was applied to investigate the formation energies,lattice parameters,electronic structures and mechanical properties of the disordered T-phases,as well as the effects of possible defects and alloying elements.The formation energy and lattice constant of the T-phase gradually vary from 0 to-0.12 eV/atom and from 1.460 to 1.405 nm,respectively,with increasing Zn contents.Zn-3d orbitals exhibit stronger hybridization with Al-3s than Mg-3s orbitals,and this is further enhanced by increasing Zn contents,leading to improved covalency and mechanical properties of the T-phase.The T-phases show good ductility according to the Poisson's ratio ν,Cauchy's pressure and G/B.The A site is more favorable to remain vacant in Al-rich and Zn-poor environments,which is consistent with the previous experimental observations.For alloying elements,Zn atoms tends to occupy Al atoms at the B,C and F sites and Mg atoms at the G sites.Both Cu and Ag elements can decrease the formation energy of T-phases and possibly produce a greater number of T-phases during the precipitation process.The effect of Ag is more significant relative to Cu due to the deeper orbital hybridization.The computational results show good agreement with previous experimental data and provide new insights into the compositional design of new Al-Mg-Zn alloys.

Anisotropic Mechanical Response of Nacre to Heat Treatment Under Indentation:Effect of Structural Orientation

It is generally considered that heat treatments have a negative impact on the mechanical properties of nacre due to thermal decomposition of the organic matrix.However,the present work investigated the microindentation behavior on fresh and heat-treated nacres from two orthogonal directions,and the results demonstrate that both hardness value and damage tolerance can remain almost unchanged on the cross-section with the organic matrix degeneration,despite a significant deterioration on the platelet surface.Theoretical analyses suggest that the anisotropic response of indentation behavior to heat treatment in nacre is primarily caused by its structural orientation.Specifically,compared with a single layer of irregular interplatelet interfaces in cross-sectional specimens,the multiple layers of parallel interlamellar interfaces in in-plane specimens exhibit a much greater ability to impede indenter-triggered destruction,and heat treatments would reduce the in-plane hardness but nearly have no effect on the cross-sectional hardness.Moreover,the deeper embedding of platelets in cross-sectional specimens enhances their resistance to interface cracking caused by organic matrix degradation at high temperatures,leading to a reduced sensitivity to damage.Therefore,the indentation behavior of nacre shows different tendencies in response to variations in the organic matrix state along normal and parallel directions.

Controlling Carbide Evolution to Improve the Ductility in High Specific Young’s Modulus Steels

A high specific Young’s modulus steel could be achieved by introducing a large fraction of kappa-carbides(κ-carbide),and its ductility was improved by efficiency divorced eutectoid transformation(DET)treatment.For this steel,carbon and aluminum contents affect not only the carbide fraction,but also the type and morphology of carbides,and consequently the mechanical properties.In this work,the alloy was designed by considering both the carbide morphology and Young’s modulus,and the carbides in the high specific Young’s modulus steels were adjusted by controlling carbon content in a suitable range for achieving a good combination of strength and ductility.The detailed microstructure evolution process during DET reaction was studied,and it was found that a higher austenitizing temperature and the cooling rate lower than 300℃ h^(−1) are suitable.The blocky carbides could be avoided by designing the carbon content in a limited content range.The microstructure-property relationship of the experimental steels was also discussed for giving an impetus to the future development of high specific Young’s modulus steels.

Surface-structure tailoring of ultrafine PtCu nanowires for enhanced electrooxidation of alcohols

Surface tailoring of Pt-based nanocatalysts is an effective pathway to promote their electrocatalytic performance and multifunctionality.Here,we report two kinds of one-dimensional(1D)ultrafine PtCu nanowires(smooth surface&rugged surface)synthesized via a wet chemical method and their distinct catalytic performances in electro-oxidation of alcohols.The alloyed PtCu nanowires having rough surfaces with atomic steps exhibit superior catalytic activity toward multiple electrochemical reactions compared with the smooth counterpart.Density functional theory simulations show the excellent reactivity of rugged PtCu na-nowires and attribute it to the surface synergetic Pt-Cu site which accounts for the promotion of water dissociation and the dehydrogenation of the carboxyl intermediate.The current study provides an insight into reasonable design of alloy nanocatalysts in energy-related electrocatalytic systems.

Microstructural Characterization and Hardness Behavior of a Biological Saxidomus purpuratus Shell

The microstructures of the Saxidomus purpuratus shell were observed.It was found that the inner and middle layers of the shell are composed of crossed lamellae,while the outer layer exhibits porous structures.With the characteristic structure of each layer,the hardness of inner layer with narrow domains in crossed lamellar structure is the highest,and that of middle layer with wide domains is lower,while the outer layer has the lowest hardness.The damage morphologies of the indentations change a lot,depending not only upon the magnitude of the indentation load,but also upon the orientation between the indentation direction and the crossed lamellae in the microstructure of the shell,which illustrates the anisotropy in mechanical properties of such shells.

Optimization of Grain Boundary Character Distribution in Fe-18Cr-18Mn-0.63N High-Nitrogen Austenitic Stainless Steel

Grain boundary engineering（GBE） is a practice of improving resistance to grain boundary failure of the material through increasing the proportion of low Σ coincidence site lattice（CSL） grain boundaries（special grain boundaries） in the grain boundary character distribution（GBCD）. The GBCD in a cold rolled and annealed Fe-18Cr-18Mn-0.63N high-nitrogen austenitic stainless steel was analyzed by electron back scatter difraction（EBSD）. The results show that the optimization process of GBE in the conventional austenitic stainless steel cannot be well applied to this high-nitrogen austenitic stainless steel. The percentage of low ΣCSL grain boundaries could increase from 47.3% for the solid solution treated high-nitrogen austenitic stainless steel specimen to 82.0% for the specimen after 5% cold rolling reduction and then annealing at 1423 K for 10 min.These special boundaries of high proportion efectively interrupt the connectivity of conventional high angle grain boundary network and thus achieve the GBCD optimization for the high-nitrogen austenitic stainless steel.

Novel injectable and self-setting composite materials for bone defect repair

Although calcium sulfate bone cements possess favorable characteristics of excellent clinical handling and osteoconductivity,the rapid degradation and poor bioactivity limit their wide applications.This study reports a type of novel injectable and self-setting composite materials for bone defect repair.Magnesium substituted tricalcium phosphate nanoparticles(43.8±9.0 nm)and calcium sulfate hemihydrate micro-size particles(5–21μm)were mixed with a polyvinyl alcohol solution with optimal compositions to obtain the composite materials,which showed reasonable initial setting time(11.7–19.2 min)and suitable compressed strength(2.28–6.33 MPa).By utilizing magnesium powder as a porogen,macro-pores(>100μm)together with micro-pores were created in the final product after setting.In addition,MC3T3-E1 cells extended well and exhibited numerous lamellipodia and long filopodia when cultured with the composite materials,indicating that they had no cytotoxicity.The in vivo results indicated that the injectable composite materials could achieve bone defect repair,when implanted in beagle femoral condyle defects for 10 months.Our results show that the new injectable composite materials are biocompatible and biodegradable,which possess great potential for bone defect repair.

Design, synthesis, and fungicidal activity of novel 1,3,4-oxadiazole derivatives

Employing the intermediate derivatization method（IDM）, twenty novel 1,3,4-oxadiazole derivatives containing arylpyrazoloxyl moiety were designed and synthesized. The structures of the title compounds were identified by1 H NMR,13 C NMR, MS and elemental analyses, compound 4 was further identified by single-crystal X-ray diffraction. Antifungal activities against rice sheath blight（RSB） and sorghum anthracnose（SA） were evaluated by the mycelium linear growth rate method. Compounds 4, 16 and 20 displayed significant activities against RSB（EC50= 0.88 mg/L, 0.91 mg/L and 0.85 mg/L, respectively）,higher than the reference tebuconazole; While compound 3 exhibited higher activity against SA（EC50= 1.03 mg/L）, equal to commercial pyraclostrobin（EC50= 1.06 mg/L）. The study showed that compound 20 is a promising fungicide for further development.

Structural changes of a bacteriophage upon DNA packaging and maturation

Dear Editor,Tailed,double-stranded DNA(dsDNA)bacteriophages,which belong to the order of Caudovirales,have a tail attached to a pentameric vertex of the icosahedral capsid shell(head)through a 12-fold portal(Johnson and Chiu,2007).The phages package genomic dsDNA into a round procapsid using the portal in complex with an ATP-dependent terminase complex as the motor.During packaging,the procapsid shell expands to a more angular intermediate to match the size of the viral genome(Guo et al.,2014).When the phage head is full,the portal detects internal pressure and conveys a signal from the inner capsid to the exterior,which triggers a sequence of events-the terminase complex cleaving mature DNA genome from a multi-genome concatemer,the release of the terminase complex from the portal,and the attachment of the tail complex-in the completion of phage assembly(Lander et al.,2006;Johnson and Chiu,2007).At the beginning of phage infection,the tail is responsible for receptor recognition,and the portal and tail act as a tunnel for DNA delivery into the host cytoplasm(Johnson and Chiu,2007).These mechanisms of DNA packaging and ejection may also be conserved in many other DNA viruses,including herpesvirus(Wang et al.,2020;Yang et al.,2020).

A Geometric Strategy Algorithm for Orthogonal Pro jection onto a Parametric Surface

In this paper, we investigate how to compute the minimum distance between a point and a parametric surface, and then to return the nearest point (foot point) on the surface as well as its corresponding parameter, which is also called the point projection problem of a parametric surface. The geometric strategy algorithm (hereafter GSA) presented consists of two parts as follows. The normal curvature to a given parametric surface is used to find the corresponding foot point firstly, and then the Taylor's expansion of the parametric surface is employed to compute parameter increments and to get the iteration formula to calculate the orthogonal projection point of test point to the parametric surface. Our geometric strategy algorithm is essentially dependent on the geometric property of the normal curvature, and performs better than existing methods in two ways. Firstly, GSA converges faster than existing methods, such as the method to turn the problem into a root-finding of nonlinear system, subdividing methods, clipping methods, geometric methods (tangent vector and geometric curvature) and hybrid second-order method, etc. Specially, it converges faster than the classical Newton's iterative method. Secondly, GSA is independent of the initial iterative value, which we prove in Theorem 1. Many numerical examples confirm GSA's robustness and efficiency.

Growth Ring-dependent Fracture Toughness of Sea Urchin Spines Estimated by Boundary Effect Model

Although the fracture behavior of sea urchin spines has been extensively investigated,there is as yet a lack of quantitative estimation on the effect of growth rings on the fracture properties of sea urchin spines.In sea urchin spines,much denser pores present in growth rings rather than porous layers.The tensile strength and fracture toughness of sea urchin spine samples with different numbers of growth rings are measured by the Boundary Effect Model(BEM).The experimental results of single-edge notched three-point bending tests indicate that the BEM is an appropriate method to estimate the fracture toughness of the present porous sea urchin spines,and the number of growth rings plays an important role in the fracture properties of spines.Specifically,the tensile strength and fracture toughness of sea urchin spines can be significantly improved with the increase in the number of growth rings,and their fracture toughness can even reach a relatively high value compared with some other porous materials with an identical porosity.The present research findings are expected to provide a fundamental insight into the design of high-performance bionic materials with a highly porous structure.