Synthesis and gas permeation parameters of metathesis polytricyclononenes with pendant Me3E‐groups (E = C,Si, Ge)

Metathesis polytricyclononenes were synthesized via ROMP polymerization in the presence of the 1‐st generation Grubbs catalyst and their gas‐transport properties were studied for the first time. The aim of this work was to evaluate the influence of Me₃E‐groups (E = C, Si, Ge) on gas permeation parameters of ROMP materials. New metathesis poly(3‐tert‐butyltricyclononene‐7) and poly(3‐trimethylgermyltricyclononene‐7) were obtained with high yields (up to 95%) and high‐molecular weights (M_w～3–7×10⁵ g mol^?1). The glass transition temperatures of the ROMP polytricyclononenes with Me₃E‐groups decreased when E was changed from C to Si and then to Ge. It was shown that the polytricyclononene containing Me₃Si‐groups has the highest gas permeability while the polytricyclononene containing Me₃C‐substituents has the lowest gas permeability. In addition, the gas permeation parameters were estimated for ROMP Me₃Si‐ and Me₃Ge‐substituted polytricyclonona‐3,7‐dienes. So the influence of the second double bond in the monomer units on the permeability of the polymers obtained was studied. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41395.     

用LED寻找故障的电缆测试仪

本例描述了一个简单的电缆测试仪,它能形象地显示出一根16线电缆束(用于超声辅助驻车系统)的通断问题。一家承包商小批量地生产该线束,因此不适合采用自动化测试仪。为简单起见,用测试信号驱动几只LED,形象化地表示出通断情况。图1中的电路产生一个从0至15的二进制数(0000至1111)。可     

An adsorptive transfer technique coupled with brdicka reaction to reveal the importance of metallothionein in chemotherapy with platinum based cytostatics

The drugs based on platinum metals represent one of the oldest, but also one of the most effective groups of chemotherapeutic agents. Thanks to many clinical studies it is known that resistance of tumor cells to drugs is a frequent cause of chemotherapy failure. With regard to platinum based drugs, multidrug resistance can also be connected with increased expression of low-molecular weight protein metallothionein (MT). This study aimed at investigating the interactions of MT with cisplatin or carboplatin, using the adsorptive transfer technique coupled with differential pulse voltammetry Brdicka reaction (AdTS DPV Brdicka reaction), and a comparison of in vitro results with results obtained in vivo. The results obtained from the in vitro study show a strong affinity between platinum based drugs and MT. Further, we analyzed extracts of neuroblastoma cell lines treated with cisplatin or carboplatin. It is clear that neuroblastoma UKF-NB-4 cisplatin-resistant and cisplatin-sensitive cell lines unlikely respond to the presence of the platinum-based cytostatics cisplatin and carboplatin. Finally, we determined the level of MT in samples from rabbits treated with carboplatin and patients with retinoblastoma treated with the same drug.     

冰硬度试验台设计与试验

极地冰层硬度特性对铠装电缆电动机械取心钻具反扭装置设计和使用具有重要意义。针对冰层特殊的物理性质,结合材料硬度测试原理,设计了一套可在模拟极地冰层低温条件下测量冰硬度特性的硬度试验台。该试验台由低温冷柜、硬度测试台和数据采集及控制系统3部分组成,其中,数据采集及控制系统隔离在常温环境中,降低了元器件对环境温度的要求。利用该试验台对硬度压头压入冰层的压力和深度进行数据检测,换算得到相应的硬度值。对设计的试验台进行初步实验表明,该试验台工作状态良好,数据准确,可满足对低温材料硬度特性的检测。     

Chemical Markers of Human Tendon Health Identified Using Raman Spectroscopy: Potential for In Vivo Assessment

The purpose of this study is to determine whether age-related changes to tendon matrix molecules can be detected using Raman spectroscopy. Raman spectra were collected from human Achilles (n = 8) and tibialis anterior (n = 8) tendon tissue excised from young (17 ± 3 years) and old (72 ± 7 years) age groups. Normalised Raman spectra underwent principal component analysis (PCA), to objectively identify differences between age groups and tendon types. Certain Raman band intensities were correlated with levels of advanced glycation end-product (AGE) collagen crosslinks, quantified using conventional destructive biochemistry techniques. Achilles and tibialis anterior tendons in the old age group demonstrated significantly higher overall Raman intensities and fluorescence levels compared to young tendons. PCA was able to distinguish young and old age groups and different tendon types. Raman intensities differed significantly for several bands, including those previously associated with AGE crosslinks, where a significant positive correlation with biochemical measures was demonstrated. Differences in Raman spectra between old and young tendon tissue and correlation with AGE crosslinks provides the basis for quantifying age-related chemical modifications to tendon matrix molecules in intact tissue. Our results suggest that Raman spectroscopy may provide a powerful tool to assess tendon health and vitality in the future.     

Fabrication of buried microfluidic channels with observation windows using femtosecond laser photoablation and parylene-C coating

We developed an advanced method for fabricating microfluidic structures comprising channels and inputs/outputs buried within a silicon wafer based on single level lithography. We etched trenches into a silicon substrate, covered these trenches with parylene-C, and selectively opened their bottoms using femtosecond laser photoablation, forming channels and inputs/outputs by isotropic etching of silicon by xenon difluoride vapors. We subsequently sealed the channels with a second parylene-C layer. Unlike in previously published works, this entire process is conducted at ambient temperature to allow for integration with complementary metal oxide semiconductor devices for smart readout electronics. We also demonstrated a method of chip cryo-cleaving with parylene presence that allows for monitoring of the process development. We also created an observation window for in situ visualization inside the opaque silicon substrate by forming a hole in the parylene layer at the silicon backside and with local silicon removal by xenon difluoride vapor etching. We verified the microfluidic chip performance by forming a segmented flow of a fluorescein solution in an oil stream. This proposed technique provides opportunities for forming simple microfluidic systems with buried channels at ambient temperature.     

Comet assay demonstrates a higher ultraviolet B sensitivity to DNA damage in dysplastic nevus cells than in common melanocytic nevus cells and foreskin melanocytes

We used the single cell gel electrophoresis assay (comet assay) to study ultraviolet B (UVB)-induced DNA damage in pigment cells. This assay detects DNA damage, mainly DNA strand breaks and alkali labile sites in the DNA molecule. We studied the effect of biologically relevant doses (comparable to 2-3 MED (minimal erythemal dose) for in vivo irradiated full-thickness skin) of monochromatic UVB light of 302 nm on cultured melanocytes derived from foreskin, common melanocytic nevi, and dysplastic nevi. We were able to demonstrate a linear dose-response relationship between UV dose and the migration coefficient of the comet tail in all three types of pigment cells. Nevus cells originating from dysplastic nevi showed the highest sensitivity to UVB irradiation: 65% higher induction of DNA damage compared to the induction in foreskin melanocytes. Common melanocytic nevus cells were most resistant and showed a 30% lower induction of DNA damage in comparison to foreskin melanocytes. Differences in chromatin structure and cell cycle profile may influence the results of the comet assay. Control experiments with x-ray irradiation, which is well known to produce direct DNA strand breaks via radical formation, revealed only small differences between the three types of melanocytic cells. It is unlikely, therefore, that intrinsic nuclear characteristics may account for the observed differences.     

Decay of end effects in graphite/epoxy bolted joints

Almost all analyses of large structures neglect local effects due to the application of loads and due to the transfer of loads between structural elements. In recent years, however, the use in aircraft structures of highly anisotropic materials, such as graphite/epoxy, has motivated more detailed studies of the applicability of Saint-Venant's principle.

In this paper in graphite/epoxy is analysed using the finite element method (FEM). The influence of anisotropy and transition from a thicker to a thinner laminate cross-section (ply-drop) is investigated. The characteristic decay length which is large for highly anisotropic materials is lessened by a change in thickness.     

Automatic learners with feedback queries

Automatic classes are classes of languages for which a finite automaton can decide whether a given element is in a set given by its index. The present work studies the learnability of automatic families by automatic learners which, in each round, output a hypothesis and update a long-term memory, depending on the input datum, via an automatic function. Many variants of automatic learners are investigated: where the long-term memory is restricted to be the current hypothesis whenever this exists, cannot be of length larger than the length of the longest datum seen, or has to consist of a constant number of examples seen so far. Learnability is also studied with respect to queries which reveal information about past data or past computation history; the number of queries per round is bounded by a constant.