发展变化中的挤出技术

挤出技术的发展越来越具有如下特色：一方面要求挤出系统高效率，另方面又要求挤出系统具有灵活性、广泛适应性。应用广泛的高效挤出系统应兼顾这两个方面。

Etiology and consequences of thrombosis in abdominal vessels

The thrombophilia which can be either congenital or acquired in adult life has major implications in the abdominal vessels. The resulting portal vein thrombosis, Budd-Chiari syndrome and mesenteric vein thrombosis have a variety of consequences ranging from acute abdomen to chronic hepatomegaly and even totally asymp- tomatic patient in whom the only finding is pancytopenia. The complications like esophageal varices, portal gastropathy, ascites, severe hypersplenism, liver failure requiring liver transplantation are well known. Interesting features of collateral venous circulation showing itself as pseudocholangiocarcinoma sign and its possible clinical reflection as cholestasis are also known from a long time. The management strategies for these complications of intraabdominal vessel thrombosis are not different from their counterpart which is cirrhotic portal hypertension, but the prognosis is unquestionably better in former cases. In this review we presented and discussed the abdominal venous thrombosis, etiology and the resulting clinical pictures. There are controversial issues both in nomenclature, and management including anticoagulation problems and follow up strategies. In light of the current knowledge, we discussed some controversial issues in literature and presented our experience and our proposals about this group of patients.

Retinal vein thrombosis associated with pegylated-interferon and ribavirin combination therapy for chronic hepatitis C

An estimated 300 million people worldwide suffer from chronic hepatitis C with a prevalence of 0.8%-1.0% of the general population in Canada. An increasing pool of evidence exists supporting the use of pegylated-interferon （pegIFN） and ribavirin combination therapy for hepatitis C. We report a 49-year old male of North American aboriginal descent with chronic hepatitis C （genotype 2b）. Biopsy confirmed that he had cirrhosis with a 2-wk history of left eye pain and decreased visual acuity. He developed retinal vein thrombosis after 16 of 24 wk of pegIFN-α 2a and ribavirin combination therapy. He was urgently referred to a retinal specialist and diagnosed with non-ischemic central retinal vein occlusion of the left eye. PegIFN and ribavirin combination therapy was discontinued and HCV RNA was undetectable after 16 wk of treatment. Hematologic investigations revealed that the patient was a factor V Leiden heterozygote with mildly decreased protein C activity. Our patient had a number of hypercoagulable risk factors, including factor V Leiden heterozygosity, cirrhosis, and hepatitis C that alone would have most likely remained clinically silent. We speculate that in the setting of pegIFN treatment, these risk factors may coalesce and cause the retinal vein thrombosis.

Branch retinal vein thrombosis and visual loss probably associated with pegylated interferon therapy of chronic hepatitis C

Ophthalmological complications with interferon therapy are usually mild and reversible, not requiring the withdrawal of the treatment. We report a case of a patient who had visual loss probably associated with interferon therapy. Chronic hepatitis C virus infection （genotype la） was diagnosed in a 33-year old asymptomatic man. His past medical history was unremarkable and previous routine ophthalmologic check-up was normal. Pegylated interferon alpha and ribavirin were started. Three weeks later he reported painless reduction of vision. Ophthalmologic examination showed extensive intraretinal hemorrhages and cottonwool spots, associated with inferior branch retinal vein thrombosis. Antiviral therapy was immediately discontinued, but one year later he persists with severely decreased visual acuity. This case illustrates the possibility of unpredictable and severe complications during pegylated interferon therapy.

Mixed P3HT/PCBM Organic Thin-Film Transistors： Relation between Morphology and Electrical Characteristics

The mixed P3HT （poly（3-hexylthiophene）） and [6,6]-PCBM （phenyl C61-butyric acid methyl ester） organic thin films were investigated for electronic structure using UV-Vis spectrophotometer and PESA （photo-electron spectroscopy in air）. Furthermore, ESR （electron spin resonance） and AFM （atomic force microscopy） were used to investigate the surface morphology and molecular orientation, respectively. ESR analysis indicated the molecular orientation of the P3HT crystalline in the blend thin films, which the crystalline oriented normal to the substrate with distribution of 35°. AFM images indicated that the surface morphology of P3HT film was affected by the presence of PCBM nanoparticles. Solution-processed OTFTs （organic thin-film transistors） based on P3HT/PCBM blend thin film in a top source-drain contact structure was fabricated, and the electrical characteristics of the devices were also investigated. A unipolar property with p-channel characteristics were obtained in glove box measurement.

The Microscopic Surgical Treatment for Tumor of Posterior Cranial Fossa in Children

OBJECTIVE To analyze and discuss about the clinicalcharacteristics, pathological types, surgical modalities andtechniques, and postoperative complications in children withtumor of posterior cranial fossa .METHODS Retrospective study was conducted on 102 cases ofpediatric tumor of posterior cranial fossa, admitted and treated inour hospital during the period of January 1996 to January 2007.All patients underwent microscopic surgical treatment. Fifty-eight were male and 44 cases were female. The age ranged from 9months to 14 years old, with an average of 6.1 ± 0.5 of age. CranialCT or MRI examination was conducted before and after thesurgery on all patients.RESULTS The primary manifestations for this group of patientswere increased intracranial pressure and/or ataxia. Postoperativepathological diagnoses showed: 46 cases of medulloblastoma, 43cases of astrocytoma, 11 cases of ependymoma (including 1 caseof degenerative ependymoma), 1 case of dermoid cyst, and 1 caseof teratoma. In this group of the patients, radical surgery wasused in 68 cases and subtotal surgical removal used in 31 cases,while surgical removal of large section was performed on 3 cases.There were no deaths from surgery reported. Ninety-one casesshowed significant symptomatic improvement when comparedwith preoperative conditions, while 11 cases showed either noimprovement or more severely affected afterward. For 6 cases,postoperative ventriculoperitoneal shunt was performed within7 days to 2 months after the surgery. Sixty-three patients gainedfollow-up for 3 to 60 months in duration. Thirty-nine patientsregained normal life and were able to learn well, while there were7 patients who could not live normally on their own. During thefollow-up period, there were 17 cases of recurrence and 7 casesof death. In 23 cases of medulloblastoma in children with age of3 years old or above, 2 cases who underwent surgical removal ofintracranial ependymoma received small dosage of postoperativeX-ray radiotherapy on the the brain and spinal cord. Nine casesof medulloblastoma in children under age of 3 and 17 cases ofastrocytoma diagnosed after the surgery received chemotherapyof Carmustine.CONCLUSION Medulloblastomas and astrocytomas werethe most common types of pediatric tumor of posterior cranialfossa, right followed by ependymoma, and dermoid cysts andteratomas were rare. Early correct diagnosis, proper selection ofappropriate surgical modality and the surgical margin, propertreatment of postoperative complications, and the selecting rightradiotherapy or chemotherapy were the key factors in influencingthe prognostic outcome of children with tumor of posterior cranialfossa.

Regularity analysis of wrinkles under the action of capillary force in an annular thin film

The wrinkling law of annular sheet which is induced by capillary force with inner liquid film is analyzed in this paper.The results show that the inner liquid film can wrinkle the annular sheet when the surface tension of the liquid film reaches a critical value,and the critical value can be dramatically altered by changing the geometry and properties of the annular sheet.The results obtained in this article may hold potential applications in generating three-dimensional structures through capillary effects.

Growth control of peptide-nanotube spherulitic films： Experiments and simulations

Multi-hierarchical self-assembly （MHSA） is a key process responsible for the spontaneous formation of many complex structures. However, because of the complexity of the process, the underlying mechanism remains largely unclear. Thus, a deeper understanding of MHSA is required, especially for the preparation of MHSA systems via bottom-up methodologies. We show here, experimentally and theoretically, that the complex-formation MHSA of peptide nanotube films can be controlled solely by manipulating the experimental parameter of humidity. Furthermore, we identify growth-front nucleation （GFN; the formation of new grains at the perimeter） as the physical background for the observed morphological transitions by correlating experimental observations with phase-field modeling of the morphological evolution. Our findings indicate a simple way to control multi-hierarchical morphologies, crucial for the employment of bottom-up techniques in constructing complex structures for practical applications.

A new pseudo rubrene analogue with excellent film forming ability

A novel pseudo rubrene analogue,6,11-di(thiophen-2-yl)-tetracene-5,12-dione (DTTDO) was synthesized,in which two thienyl groups and two carbonyl groups replacing four phenyl groups in the rubrene molecule were connected to the backbone of tetracene.This compound was characterized by single crystal X-ray structure analysis,thermogravimetric analysis,absorption spectra and electrochemical measurements.Unlike rubrene,DTTDO exhibited excellent film forming ability by normal vacuum deposition,indicating its promising applications in organic thin film transistors.

Mechanical behavior of pathological and normal red blood cells in microvascular flow based on modified level-set method

The research of the motion and deformation of the RBCs is important to reveal the mechanism of blood diseases. A numerical method has been developed with level set formulation for elastic membrane immersed in incompressible fluid. The numerical model satisfies mass and energy conservation without the leaking problems in classical Immersed Boundary Method(IBM), at the same time, computing grid we used can be much smaller than the general literatures. The motion and deformation of a red blood cell(including pathological & normal status) in microvascular flow are simulated. It is found that the Reynolds number and membrane's stiffness play an important role in the transmutation and oscillation of the elastic membrane. The normal biconcave shape of the RBC is propitious to create high deformation than other pathological shapes. With reduced viscosity of the interior fluid both the velocity of the blood and the deformability of the cell reduced. With increased viscosity of the plasma both the velocity of the blood and the deformability of the cell reduced. The tank treading of the RBC membrane is observed at low enough viscosity contrast in shear flow. The tank tread fixed inclination angle of the cell depends on the shear ratio and viscosity contrast, which can be compared with the experimental observation well.