Highly toughened polylactide with novel sliding graft copolymer by in situ reactive compatibilization, crosslinking and chain extension

YesThe “sliding graft copolymer” (SGC), in which many linear poly-ε-caprolactone (PCL) side chains are bound to cyclodextrin rings of a polyrotaxane (PR), was prepared and employed to toughen brittle polylactide (PLA) with methylene diphenyl diisocyanate (MDI) by reactive blending. The SGC was in situ crosslinked and therefore transformed from a crystallized plastic into a totally amorphous elastomer during reactive blending. Meanwhile, PLA-co-SGC copolymer was formed at interface to greatly improve the compatibility between PLA and SGC, and the chain extension of PLA also occurred, were confirmed by FTIR, GPC, SEM, and TEM. The resulting PLA/SGC/MDI blends displayed super impact toughness, elongation at break and nice biocompatibility. It was inferred from these results the crosslinked SGC (c-SGC) elastomeric particles with sliding crosslinking points performed as stress concentrators and absorbed considerable energy under impact and tension process.This work was supported by the National Natural Science Foundation of China (50933001, 51221002 and 51320105012)

Applicability of Preoperative Nuclear Morphometry to Evaluating Risk for Cervical Lymph Node Metastasis in Oral Squamous Cell Carcinoma

Background: We previously reported the utility of preoperative nuclear morphometry for evaluating risk for cervical lymph node metastases in tongue squamous cell carcinoma. The risk for lymph node metastasis in oral squamous cell carcinoma, however, is known to differ depending on the anatomical site of the primary tumor, such as the tongue, gingiva, mouth floor, and buccal mucosa. In this study, we evaluated the applicability of this morphometric technique to evaluating the risk for cervical lymph node metastasis in oral squamous cell carcinoma. Methods: A digital image system was used to measure the mean nuclear area, mean nuclear perimeter, nuclear circular rate, ratio of nuclear length to width (aspect ratio), and nuclear area coefficient of variation (NACV). Relationships between these parameters and nodal status were evaluated by t-test and logistic regression analysis. Results: Eighty-eight cases of squamous cell carcinoma (52 of the tongue, 25 of the gingiva, 4 of the buccal mucosa, and 7 of the mouth floor) were included: 46 with positive node classification and 42 with negative node classification. Nuclear area and perimeter were significantly larger in node-positive cases than in nodenegative cases; however, there were no significant differences in circular rate, aspect ratio, or NACV. We derived two risk models based on the results of multivariate analysis: Model 1, which identified age and mean nuclear area and Model 2, which identified age and mean nuclear perimeter. It should be noted that primary tumor site was not associated the pN-positive status. There were no significant differences in pathological nodal status by aspect ratio, NACV, or primary tumor site. Conclusion: Our method of preoperative nuclear morphometry may contribute valuable information to evaluations of the risk for lymph node metastasis in oral squamous cell carcinoma

Modeling and experimental analysis of direct contact heat exchangers for R718 refrigeration system

Natural refrigerants are taking an increasing place in the refrigeration market today. Water is one of the most abundant and safest working fluids. However, the literature on water based refrigeration systems is very scarce, in particular regarding experimental works. Besides, the design of heat exchangers for water-based systems is very specific. The design quality has a huge consequence on the performance and capacity of such systems. Thus, the development and validation of mathematical models used for the sizing and the design of such heat exchangers are very important. This paper presents mathematical models of direct contact lowpressure heat exchangers for steam evaporation and condensation. These models are part of a complete refrigeration system model developed on Dymola. The modeling results are compared to experiments done on a 10kW chiller. The Dymola model combined to a one-dimensional model of the heat exchanger predicts well the operating pressures and the heat transfer performances. The experimental results were also used to build empirical models of the global heat transfer coefficient. The heat transfer appears to be mainly affected by the steam to liquid flow rates fraction, the liquid flow rate and the condensing power

The development of system based on natural refrigerants has been very important in these recent decades, in order to mitigate global warming, pollution, but also against environmental risks and those related to health and safety. Water is undoubtedly one of the most abundant and safest refrigerants on the planet. Nevertheless, existing studies on water as a working fluid are few and often theoretical. They are mainly limited by the unavailability of a suitable compressor on the market, making experimental study of this refrigerant complex. A prototype of small capacity two-stage high-speed centrifugal compressor has been used in this study to explore R718 refrigeration cycles in medium temperature applications (cold water from 7°C to 25°C). In this paper, we are studying R718 in a direct exchange mechanical vapor compression refrigeration cycle with and without assistance of a two-phase ejector. The experimental bench is presented and the performances of the refrigeration cycle with and without two-phase ejector are analyzed.

International audienc

Experiment and theoretical comparison of two novel R718 refrigeration cycles in medium temperature chiller

International audienceThe development of system based on natural refrigerants has been very important in these recent decades, in order to mitigate global warming, pollution, but also against environmental risks and those related to health and safety. Water is undoubtedly one of the most abundant and safest refrigerants on the planet. Nevertheless, existing studies on water as a working fluid are few and often theoretical. They are mainly limited by the unavailability of a suitable compressor on the market, making experimental study of this refrigerant complex. A prototype of small capacity two-stage high-speed centrifugal compressor has been used in this study to explore R718 refrigeration cycles in medium temperature applications (cold water from 7°C to 25°C). In this paper, we are studying R718 in a direct exchange mechanical vapor compression refrigeration cycle with and without assistance of a two-phase ejector. The experimental bench is presented and the performances of the refrigeration cycle with and without two-phase ejector are analyzed