高聚度软质PVC抗静电材料的开发

为了赋予高聚合度PVC制品优良的抗静电性 ,添加导电炭黑 (SCF)、乙炔炭黑或液体抗静电剂SP - 8,确定其加工工艺。结果表明 ,空壳结构的导电炭黑 ,随添加量增加 ,表面电阻Rs 可降至 10 0MΩ ;乙炔炭黑添加量较大 ,加工工艺控制困难 ,不适用于改良软质HPVC制品的导电性能 ;抗静电剂SP- 8添加量为 2 %以上 ,表面电阻Rs最低只能降至 10MΩ。最佳塑炼温度 :16 0～ 180℃ ,时间 :5～

Positioning planning of high-intensity-focused ultrasound surgery platform using Bezier curve

A positioning volume ellipsoid method is proposed to represent tumor volume in the workspace of a high-intensity-focused ultrasound (HIFU) surgery platform during the platform's positioning motion. To this simplified tumor model, a nearest neighbor search method is used to determine intermediate configuration and goal configuration, which the treatment head and ultrasound focus must pass in their localization to target volume. Based on the decided configurations, the continuity condition of combined Bezier curve in Euclidean space and De Casteljau algorithm on Lie group SO(3) are integrated to construct a combined Bezier positioning path of C2 continuity at junctional configuration, and an illustration of different positioning path planning is analyzed based on a liver tumor case.

In-situ reactive compatibilization of HDPE/GTR blends by dicumyl peroxide and phenolic resin without catalyst

In-situ reactive compatibilization of high-density polyethylene （HDPE）/ground tire rubber （GTR） blends by dicumyl peroxide （DCP） and HY-2045 - a kind of thermoplastic phenolic resin without catalyst was investigated by studying the mor-phology, stress and strain behavior, dynamic mechanical properties and crystallization performance of the blends. Scanning e-lectron microscopy （SEM） results show that there are a lot of fibrous materials distributing in the interface, which connects the dispersed phase with the matrix and obtains better interfacial strength for prominent mechanical properties. The addition of compatibilizers results in the decrease of crystallinity of the blends and the disappearance of an obvious yield phenomenon, which was proved by the differential scanning calorimeter （DSC） test and X-ray diffraction （XRD） characterization Although the crystallinity of the blends decreases,the tensile strength and tensile strain of the blends significantly increases, especially for the HDPE/GTR/DCP/HY-2045 blends, which is possibly attributed to the good compatibility of the blends owing to the in-situ interface crosslinking. In addition, it is found that the compatibilizing HDPE/GTR blends shows a higher tan^ peak temperature and a broaden transition peak for GTR phase.

Growth inhibition of high-intensity focused ultrasound on hepatic cancer in vivo

AIM： To investigate the damaging effect of high-intensity focused ultrasound （HIFU） on cancer cells and the inhibitory effect on tumor growth. METHODS： Hurine H22 hepatic cancer cells were treated with HIFU at the same intensity for different lengths of time and at different intensities for the same length oftime in vitro, the dead cancer cells were determined by trypan blue staining. Two groups of cancer cells treated with HIFU at the lowest and highest intensity were inoculated into mice. Tumor masses were removed and weighed after 2 wk, tumor growth in each group was confirmed pathologically.RESULTS： The death rate of cancer cells treated with HIFU at 1 000 W/cm^2 for 0.5, 1, 2, 4, 8, and 12 s was 3.11±1.21%, 13.37±2.56%, 38.84±3.68%, 47.22±5.76%,87.55±7.32%, and 94.33±8.11%, respectively. A positive relationship between the death rates of cancer cells and the length of HIFU treatment time was found （r = 0.96,P〈0.01）. The death rate of cancer cells treated with HIFU at the intensity of 100, 200, 400, 600, 800, and 1 000 W/cm^2 for 8 s was 26.31±3.26%, 31.00±3.87%, 41.97±5.86%,72.23±8.12%, 94.90±8.67%, and 99.30±9.18%, respectively. A positive relationship between the death rates of cancer cells and the intensities of HIFU treatment was confirmed （r= 0.98, P〈0.01）. The cancer cells treated with HIFU at 1 000 W/cm^2 for 8 s were inoculated intomice ed into. The tumor inhibitory rate was 90.35% compared to the control （P〈0.01）. In the experimental group inoculated with the cancer cells treated with HIFU at 1 000 W/cm^2 for 0.5 s, the tumor inhibitory rate was 22.9% （P〈0.01）. By pathological examination, tumor growth was confirmed in 8 out of 14 mice （57.14%, 8/14） inoculated with the cancer cells treated with HIFU at 1 000 W/cm^2 for 8 s, which was significantly lower than that in the control （100%, 15/15, P〈O.05）.CONCLUSION： HIFU is effective on killing or damage of H22 hepatic cancer cells in vitro and on inhibiting tumor growth in mice ex vivo.

Complications of high intensity focused ultrasound in patients with recurrent and metastatic abdominal tumors

AIM： To analyze the local and systemic complications of high intensity focused ultrasound （HIFU） for patients with recurrent and metastatic abdominal tumors. METHODS： From Aug 2001 to Aug 2004, 17 patients with recurrent and metastatic abdominal tumors were enrolled in this study. Real-time sonography was taken, and vital signs, liver and kidney function, skin burns, local reactions, and systemic effects were observed and recored before, during, and after HIFU. CT and MR/were also taken before and after HIFU. RESULTS： All 17 patients had skin burns and pain in the treatment region; the next common complication was neurapraxia of the stomach and intestines to variable degrees. The other local and systemic complications were relatively rare. Severe complications were present in two patients; one developed a superior mesenteric artery infarction resulting in necrosis of the entire small intestines, and the other one suffered from a perforation in terminal ileum due to HIFU treatment. CONCLUSION： Although HIFU is a one of noninvasive treatments for the recurrent and metastatic abdominal tumors, there are still some common and severe complications which need serious consideration.

Radiofrequency ablation or percutaneous ethanol injection for the treatment of liver tumors

The liver is a common location of both primary and secondary malignancies. For unresectable liver cancer, many local ablative therapies have been developed. These include e.g., percutaneous ethanol injection (PEI), percutaneous acetic acid injection, radiofrequency ablation (RFA), cryoablation, microwave ablation, laserinduced thermotherapy, and high-intensity focused ultrasound. RFA has recently gained interest and is the most widely applied thermoablative technique. RFA allows more effective tumor control in fewer treatment sessions compared with PEI, but with a higher rate of complications. However, there are certain circumstances where PEI therapy represents a better strategy to control liver tumors than RFA, especially in situations where RFA is difficult, for example when large vessels surround the tumor. In the context of hepatocellular carcinoma (HCC), both RFA and PEI are feasible and of benefit in non-operable patients. RFA seems superior to PEI in HCC > 2 cm, and the combination of interventions may be of benefit in selected patients. Liver resection is superior to RFA for patients with HCC meeting the Milan criteria, but RFA can be employed in tumors ≤ 3 cm and where there is an increased expected operative mortality. In addition, some lines of evidence indicate that RFA and PEI can be employed as a bridge to liver transplantation. The use of RFA in colorectal liver metastases is currently limited to unresectable disease and for patients unfit for surgery. The aim of this article is to summarize the current status of RFA in the management of liver tumors and compare it to the cheap and readily available technique of PEI.

The Efficacy of High-Intensity Focused Ultrasound (HIFU) in Advanced Pancreatic Cancer

OBJECTIVE To observe the efficacy of high-intensity focused ultrasound (HIFU) in the treatment of late-stage pancreatic cancer. METHODS Sixteen patients with advanced pancreatic cancer received HIFU therapy.Evaluation of efficacy was made on the basis of changes in clinical symptoms and variations in the tumor echo and size. RESULTS Clinical symptoms such as pain were significantly alleviated,echo of the tumor was enhanced with B-US and the quality of life such as eating,sleeping and mental status was markedly improved;no serious complications were observed. CONCLUSION The use of HIFU in the treatment of advanced pancreatic cancer is feasible and safe.It is effective in killing the carcinoma cells and alleviating pain.This technique may offer non-invasive therapy for the treatment of patients with late-stage pancreatic cancer.

Non-thermal ablation of rabbit liver VX2 tumor by pulsed high intensity focused ultrasound with ultrasound contrast agent:Pathological characteristics

AIM： To investigate the pathological characteristics of non-thermal damage induced by pulsed high intensity focused ultrasound （PHIFU） combined with ultrasound contrast agent （UCA）, SonoVue （Bracco SpA, Milan, Italy） in rabbit liver VX2 tumor. METHODS： Liver VX2 tumor models were established in 20 rabbits, which were divided randomly into PHIFU combined with ultrasound contrast agent group （PHIFU ＋ UCA group） and sham group. In the PHIFU ＋ UCA group, 0.2 mL of SonoVue was injected intravenously into the tumor, followed by ultrasound exposure of Isp 5900 W/cm^2. The rabbits were sacrificed one day after ultrasound exposure. Specimens of the exposed tumor tissues were obtained and observed pathologically under light microscope and transmission electron microscope. The remaining tumor tissues were sent for 2,3,5-Triphenyltetrazolium chloride （TTC） staining. RESULTS： Before Trc staining, tumor tissues in both the sham and the PHIFU ＋ UCA groups resembled gray fish meat, After TIC staining, the tumor tissues were uniformly stained red, with a clear boundary between tumor tissue and normal tissue, Histological examination showed signs of tumor cell injury in PHIFU ＋ UCA group, with cytoplasmic vacuoles of various sizes, chromatin margination and karyopyknosis. Electron microscopic examination revealed tumor cell volume reduction, karyopyknosis, chromatin margination, intercellular space widening, the presence of high electro＇n-density apoptotic bodies and vacuoles in cytoplasm. CONCLUSION： The non-thermal effects of PHIFU combined with UCA can be used to ablate rabbit liver VX2 tumors.

Minimally invasive local therapies for liver cancer

Primary and metastatic liver tumors are an increasing global health problem,with hepatocellular carcinoma(HCC)now being the third leading cause of cancer-related mortality worldwide.Systemic treatment options for HCC remain limited,with Sorafenib as the only prospectively validated agent shown to increase overall survival.Surgical resection and/or transplantation,locally ablative therapies and regional or locoregional therapies have filled the gap in liver tumor treatments,providing improved survival outcomes for both primary and metastatic tumors.Minimally invasive local therapies have an increasing role in the treatment of both primary and metastatic liver tumors.For patients with low volume disease,these therapies have now been established into consensus practice guidelines.This review highlights technical aspects and outcomes of commonly utilized,minimally invasive local therapies including laparoscopic liver resection(LLR),radiofrequency ablation(RFA),microwave ablation(MWA),high-intensity focused ultrasound(HIFU),irreversible electroporation(IRE),and stereotactic body radiation therapy(SBRT).In addition,the role of combination treatment strategies utilizing these minimally invasive techniques is reviewed.

Simulation of thermal field induced by concave spherical transducer in multi-layer media

High intensity focused ultrasound(HIFU)therapy is an effective method in clinical treatment of tumors,in order to explore the bio-heat conduction mechanism of in multi-layer media by concave spherical transducer,temperature field induced by this kind of transducer in multi-layer media will be simulated through solving Pennes equation with finite difference method,and the influence of initial sound pressure,absorption coefficient,and thickness of different layers of biological tissue as well as thermal conductivity parameter on sound focus and temperature distribution will be analyzed,respectively.The results show that the temperature in focus area increases faster while the initial sound pressure and thermal conductivity increase.The absorption coefficient is smaller,the ultrasound intensity in the focus area is bigger,and the size of the focus area is increasing.When the thicknesses of different layers of tissue change,the focus position changes slightly,but the sound intensity of the focus area will change obviously.The temperature in focus area will rise quickly before reaching a threshold,and then the temperature will keep in the threshold range.

Fine particle aggregating and flotation behavior induced by high intensity conditioning of a CO_2 saturation slurry

The influence on fine particle aggregation and flotation behavior induced by high intensity conditioning(HIC) from saturated of the slurry with CO2 saturation was investigated.Bubble size measurements were conducted.The effect of dissolved gas,xanthate addition and agitation speed on fine sphalerite particle aggregation-and flotation-behavior were studied.The results show that during HIC in air or CO2 saturated water xanthate acts as a frother.The dissolved gas content in the pulp and HIC play a synergistic role in promoting fine particle aggregation and hence flotation;a significantly enhanced aggregation of fine sphalerite particles in a CO2 saturated slurry by HIC is observed.The aggregate size increased when the agitation speed was increased from 700 r/min to 1500 r/min.Increasing the HIC speed to 1500 r/min caused a positive impact on flotation kinetics.Further increasing the speed to 2000 r/min resulted in an adverse effect on flotation kinetics.

A New Extension Theory-based Production Operation Method in Industrial Process

To explore the problems of dynamic change in production demand and operating contradiction in production process, a new extension theory-based production operation method is proposed. The core is the demand requisition, contradiction resolution and operation classification. For the demand requisition, the deep and comprehensive demand elements are collected by the conjugating analysis. For the contradiction resolution, the conflict between the demand and operating elements are solved by the extension reasoning, extension transformation and consistency judgment. For the operating classification, the operating importance among the operating elements is calculated by the extension clustering so as to guide the production operation and ensure the production safety. Through the actual application in the cascade reaction process of high-density polyethylene (HDPE) of a chemical plant, cases study and comparison show that the proposed extension theory-based production operation method is significantly better than the traditional experience-based operation method in actual production process, which exploits a new way to the research on the production operating methods for industrial process.

Effect of Extractant and Cold-drawing on the Structure and Performance of HDPE Hollow Fiber Membranes Fabricated via Thermally Induced Phase Separation Method

Microporous polyolefin hollow fiber membranes were prepared from high density polyethylene （HDPE）-paraffin solution via thermally induced phase separation （TIPS） method. Effects of extraction and cold-drawing condition on membrane structure and performance were investigated.Five volatile solvents were used as extractant. Dimension of hollow fiber and gas permeation rate of membrane were measured. Mierostructure of membrane was examined by Scanning Electronic Microscope （SEM）. The results show that the membrane treated by pentane possesses a higher porosity, nitrogen permeability and lower shrinkage than those of membranes extracted by other three extractants. It is also found that the membrane stretched 133% shows the highest porosity and gas permeability in this study.

A New Calculation of the In-Medium Quark Condensate at Finite Density and Temperature

The in-medium quark condensate is studied with an equivalent-mass approach in which one does not need to make assumptions on the derivatives of model parameters with respect to the quark current mass.It is shown that the condensate is generally a decreasing function of both the density and temperature with the decreasing speed depending on the confinement parameter.Specially,at given density,the condensate decreases on increasing temperature.The decreasing speed is comparatively small at lower temperature,and becomes very fast at higher temperature.

High density porous polyethylene material (Medpor) as an unwrapped orbital implant

Objective: To introduce the clinical effect among patients who received an unwrapped orbital implant with high density porous polyethylene material (Medpor) after enucleation or evisceration. Methods: Retrospective analysis of a series of 302 patients with anophthalmia who underwent placement of an unwrapped high density porous polyethylene orbital implant. We compared the patients (n=180) who accepted primary implant placement with those (n=122) who accepted secondary implant placement. Parameters evaluated included: age at time of surgery, date of surgery, sex, implant type and size, surgery type, the surgical procedure and technique performed, and complications. Results: The time of follow-up ranged from 2.0 to 58.0 months (mean 32.5 months). A total of 5 of 302 (1.66%) cases had documented postoperative complications. The following problems were noted after surgery: implant exposure, 3 patients (0.99%); implant removed due to orbital infection, 1 patient (0.34%); ptosis, 1 patient (0.34%). There were no significant complications observed in other 297 cases and all implants showed good orbital mo- tility. The clinical effect of primary implant placement is better than that of secondary placement. Conclusion: High density porous polyethylene material can be used successfully as an unwrapped orbital implant in anopthalmic socket surgery with minimal complications. The material is well tolerated, nonantigenic and has low rate of infection and migration.

In-vivo characterization of DALM in ulcerative colitis with high-resolution probe-based confocal laser endomicroscopy

Recently,the use of confocal laser endomicroscopy(CLE) in the diagnosis of chronic ulcerative colitis(CUC) was reported.In this brief report we aimed to assess the application of probe-based CLE to characterize colonic mucosa and dysplasia in CUC.The study involved a patient presenting long-standing CUC.Confocal imaging of both the inflamed mucosa,a circumscribed lesion(dysplasiaassociated lesional mass),and adjacent colonic mucosa are demonstrated and the correlation between the CLE and histological images.Inflamed mucosa and dysplasia showed specific alteration of crypt architecture,cellular infiltration,and vessel architecture with an excellent correlation between CLE and standard histological examination.

A Methodology for Producing Uniform Distribution of UO2 in a Tungsten Matrix

We report a method to produce a uniform mixture of uranium dioxide spherical particles in a tungsten matrix. This method involves mixing 0.5 weight percent of high density polyethylene binder with 60 volume percent uranium dioxide spheres and 40 volume percent tungsten powders. Initially, hafnium oxide spheres were used as a surrogate for uranium dioxide spheres. The HfO2/W/PE powders were thoroughly mixed in a Turbula, then mixed on a hot plate above the drop point of the binder. These powders were then densified using spark plasma sintering. Microstructure was evaluated using scanning electron microscopy, density was measured and hardness measurements were made. Initial carbon content of the powders were measured and carbon content of the sintered materials was measured. Subsequently, W/UO2/Binder powders were mixed using the same methodology to ensure the process could be used for this system. These powders were sintered using hot isostatic pressing and microstructures evaluated. The resultant microstructures contained uniform distribution of HfO2 and UO2 particles in the tungsten matrix with very low carbon content.

A Study on Gradient Refractive Index Polymer Rods——Mechanism of Diffusion-Copolymerization of Diallyl Phthalate-Methyl Methacrylate

The gel rod, partially polymerized DAP (diallyl phthalate), is immersed in MMA (methyl methacrylate) solution, followed by heat-treatment to yield the GRIN (gradient ref- ractive index) rod. A three-stage mechanism of diffusion-copolymerization process is propo- sed, giving an interpretation to the formation of cracks that are brought about in large-dia- meter GRIN rods.

A hybrid genetic algorithm for multi-modal image registration

This paper describes a new method for three-dimensional medical image registration. In the interactive image-guided HIFU （ High Intensity Focused Ultrasound） therapy system, a fast and precise localization of the tumor is very important. An automatic system is developed for registering pre-operative MR images with intra-operative ultrasound images based on the vessels visible in both of the modalities. When the MR and the ultrasound images are aligned, the eenterline points of the vessels in the MR image will align with bright intensities in the ultrasound image. The method applies an optimization strategy combining the genetic algorithm with the conjugated gradients algorithm to minimize the objective function. It provides a feasible way of determining the global solution and makes the method robust to local maximum and insensitive to initial position. Two experiments were designed to evaluate the method, and the results show that our method has better registration accuracy and convergence rate than the other two classic algorithms.

Variation of the Thermal Properties of a Polyurethane-Polyethylene Composite

This paper discusses the behavior of the thermal properties of polymer composites made of a natural polyurethane matrix and loads of different waste of HDPE （High density polyethylene） industry. This polymer is partially crystalline, having amorphous phases and crystalline phases, HDPE type is harder and tougher than other polyethylenes, having a wide range of applications that depend almost exclusively on the processes for obtaining final products. After the process, waste from the manufacture of these products are discarded daily as they are not found effective ways to use this material. In this study we seek to use this ＂factory floor＂ to act as filler in a polyurethane matrix derived from the castor oil, which is a natural biodegradable. The residue loads were separated according to the process that originated in this way have been the A residue from the process of cork and the B residue derived from the extrusion process. Specimens in mass proportions of 10%, 20% and 30% polyethylene both loads were prepared and their thermal properties were mediated, these being the thermal conductivity （k）, specific heat （c） and thermal diffusivity （~）. By adding such fillers to castor polyurethane matrix, different behaviors were observed, because of the residue contributed to a reduction in conductivity and specific heat of the composite material. Since the residue B on average 47% higher than residue, caused an increase in these same properties as before the spaces filled with air only into the polyurethane are now filled with polyethylene grains. We can see then that the particle size of the HDPE waste has a direct influence on the improvement of the thermal properties of the analyzed composite material.