Fully biobased and supertough polylactide-based thermoplastic vulcanizates fabricated by peroxide-induced dynamic vulcanization and interfacial compatibilization.

A fully biobased and supertough thermoplastic vulcanizate (TPV) consisting of polylactide (PLA) and a biobased vulcanized unsaturated aliphatic polyester elastomer (UPE) was fabricated via peroxide-induced dynamic vulcanization. Interfacial compatibilization between PLA and UPE took place during dynamic vulcanization, which was confirmed by gel measurement and NMR analysis. After vulcanization, the TPV exhibited a quasi cocontinuous morphology with vulcanized UPE compactly dispersed in PLA matrix, which was different from the pristine PLA/UPE blend, exhibiting typically phase-separated morphology with unvulcanized UPE droplets discretely dispersed in matrix. The TPV showed significantly improved tensile and impact toughness with values up to about 99.3 MJ/m(3) and 586.6 J/m, respectively, compared to those of 3.2 MJ/m(3) and 16.8 J/m for neat PLA, respectively. The toughening mechanisms under tensile and impact tests were investigated and deduced as massive shear yielding of the PLA matrix triggered by internal cavitation of VUPE. The fully biobased supertough PLA vulcanizate could serve as a promising alternative to traditional commodity plastics.

Urethane Ionic Groups Induced Rapid Crystallization of Biodegradable Poly(ethylene succinate).

Novel urethane ionic groups were incorporated into biodegradable poly(ethylene succinate) (PES) by chain extension reaction of PES diol (HO-PES-OH) and diethanolamine hydrochloride (DEAH) using hexamethylene diisocyanate (HDI) as a chain extender. The synthesized polymer was a novel segmented poly(ester urethane) ionomer (PESI) in which the soft segments were formed by reaction of HO-PES-OH with HDI and the hard segments that contained ionic groups were derived from reaction of DEAH with HDI. The crystallization rate of PESI was dramatically accelerated when 3 mol % urethane ionic groups were incorporated. However, the crystallization mechanism did not change. The significant acceleration in crystallization rate was attributed to the improved nucleation efficiency by incorporation of the urethane ionic group, because PESI showed significantly enhanced nucleation density but slightly slowed spherurlitic growth rate in comparison with PES which was synthesized by chain extension reaction of HO-PES-OH with HDI. The increased nucleation efficiency was ascribed to the aggregation of hard segments of PESI induced by the ionic interactions.

Chitin whiskers: an overview.

Chitin is the second most abundant semicrystalline polysaccharide. Like cellulose, the amorphous domains of chitin can also be removed under certain conditions such as acidolysis to give rise to crystallites in nanoscale, which are the so-called chitin nanocrystals or chitin whiskers (CHWs). CHW together with other organic nanoparticles such as cellulose whisker (CW) and starch nanocrystal show many advantages over traditional inorganic nanoparticles such as easy availability, nontoxicity, biodegradability, low density, and easy modification. They have been widely used as substitutes for inorganic nanoparticles in reinforcing polymer nanocomposites. The research and development of CHW related areas are much slower than those of CW. However, CHWs are still of strategic importance in the resource scarcity periods because of their abundant availability and special properties. During the past decade, increasing studies have been done on preparation of CHWs and their application in reinforcing polymer nanocomposites. Some other applications such as being used as feedstock to prepare chitosan nanoscaffolds have also been investigated. This Article is to review the recent development on CHW related studies.

A pilot study on combination of cryosurgery and (125)iodine seed implantation for treatment of locally advanced pancreatic cancer.

AIM: To study the therapeutic value of combination of cryosurgery and (125)iodine seed implantation for locally advanced pancreatic cancer. METHODS: Forty-nine patients with locally advanced pancreatic cancer (males 36, females 13), with a median age of 59 years, were enrolled in the study. Twelve patients had liver metastases. In all cases the tumors were considered unresectable after a comprehensive evaluation. Patients were treated with cryosurgery, which was performed intraoperatively or percutaneously under guidance of ultrasound and/or computed tomography (CT), and (125)iodine seed implantation, which was performed during cryosurgery or post-cryosurgery under guidance of ultrasound and/or CT. A few patients received regional celiac artery chemotherapy. RESULTS: Thirteen patients received intraoperative cryosurgery and 36 received percutaneous cryosurgery. Some patients underwent repeat cryosurgery. (125)Iodine seed implantation was performed during freezing procedure in 35 patients and 3-9 d after cryosurgery in 14 cases. Twenty patients, 10 of whom had hepatic metastases received regional chemotherapy. At 3 mo after therapy, CT was repeated to estimate tumor response to therapy. Most patients showed varying degrees of tumor necrosis. Complete response (CR) of tumor was seen in 20.4% patients, partial response (PR), in 38.8%, stable disease (SD), in 30.6%, and progressive disease (PD), in 10.2%. Adverse effects associated with cryosurgery included upper abdomen pain and increased serum amylase. Acute pancreatitis was seen in 6 patients one of whom developed severe pancreatitis. All adverse effects were controlled by medical management with no poor outcome. There was no therapy-related mortality. During a median follow-up of 18 mo (range of 5-40), the median survival was 16.2 mo, with 26 patients (53.1%) surviving for 12 mo or more. Overall, the 6-, 12-, 24- and 36-mo survival rates were 94.9%, 63.1%, 22.8% and 9.5%, respectively. Eight patients had survival of 24 mo or more. The patient with the longest survival (40 mo) is still living without evidence of tumor recurrence. CONCLUSION: Cryosurgery, which is far less invasive than conventional pancreatic resection, and is associated with a low rate of adverse effects, should be the treatment of choice for patients with locally advanced pancreatic cancer. (125)Iodine seed implantation can destroy the residual surviving cancer cells after cryosurgery. Hence, a combination of both modalities has a complementary effect.

Cryosurgery with combination of (125)iodine seed implantation for the treatment of locally advanced pancreatic cancer.

OBJECTIVE: To study the therapeutic value of cryosurgery with combination of (125)iodine seed implantation for locally advanced pancreatic cancer. METHODS: Thirty-eight patients with locally advanced pancreatic cancer were enrolled in this study. The diagnosis was confirmed by pathology in 31 patients. Ten patients had metastases of the peripancreatic lymph node and eight had liver metastases. The therapy included cryosurgery, which was performed intra-operatively or percutaneously under guidance of ultrasound and/or computed tomography (CT), and (125)iodine seed implantation, which was performed during cryosurgery process or post-cryosurgery under the guidance of ultrasound and/or CT. RESULTS: Eleven patients received intra-operative cryosurgery and 27 received percutaneous cryosurgery. Fourteen patients underwent two procedures of cryosurgery and three underwent three procedures of cryosurgery. (125)Iodine seed implantation was performed during the freezing procedure in 29 patients and within 3-7 days after cryosurgery in nine patients under ultrasound and CT guidance. Fifteen patients, of whom 13 had metastases of peripancreatic lymph nodes or liver received regional chemotherapy. At 3 months after therapy, a CT follow-up was performed to estimate the tumor response to therapy. Most of the patients had varying degrees of tumor necrosis. A complete response of the tumor was seen in 23.6% of patients, a partial response in 42.1%, stable disease in 26.3% and progressive disease in 7.9%. The adverse effects associated with cryosurgery mainly included pain of the upper abdomen and increased serum amylase activity. Acute pancreatitis was seen in five patients, one of whom presented a severe type of pancreatitis. During the followed-up of a median of 16 months (range of 5-37) median overall survival was 12 months, 19 patients (50.0%) survived for 12 months or longer and four survived for 24 months or longer. CONCLUSION: As it is far less invasive than conventional pancreas resection and entails a low rate of adverse effects, cryosurgery should be the choice modality for most patients with locally advanced pancreatic cancer. (125)Iodine seed implantation can destroy residue survival cancer cells after cryosurgery. Hence, combination of both modalities has a complementary effect.