降低pH值而不增加皮肤刺激性的全氟聚醚磷酸酯盐

临床研究表明,全氟聚醚磷酸酯盐是一种温和的酸性试剂,它可以有效地降低pH值而不会增加酸性组分的其他影响.     

Grafting of polymer chains on the surface of carbon nanotubes via nitroxide radical coupling reaction

Poly(butylene succinate) (PBS) was grafted on the surface of TEMPO (2,2,6,6‐tetramethyl‐1‐piperidinyloxy) modified multi‐walled carbon nanotubes (MWCNTs) via a nitroxide radical coupling reaction. TEMPO functionalized MWCNTs (MWCNTs‐g‐TEMPO) were synthesized using the Cu(I)‐catalyzed azide/alkyne click chemistry approach and the covalent bond of the nitroxide moieties onto the MWCNTs was confirmed via electron paramagnetic resonance (EPR) spectroscopy. The PBS grafting on the sidewalls of MWCNTs was carried out in solution via peroxide‐induced formation of macroradicals and it was confirmed by EPR and attenuated total reflectance Fourier transform infrared analysis. Preliminary rheological and calorimetric analyses revealed that the grafting improves both the quality of stress transfer across the polymer ? nanotube interface and the degree of dispersion of the filler, which also exhibited a moderate nucleating action on the PBS. Overall, our results demonstrate that nitroxide radical coupling is an efficient and feasible ‘grafting to’ method to covalently bond polymer chains on MWCNTs with possible advantages in the final properties of the polymer nanocomposites. © 2015 Society of Chemical Industry     

Optoelectronic properties of a perylene substituted (cholesteryl)benzoateethynylene co-polymer

A perylene cholesteryl-benzoateethynylene co-polymer was synthesized by Sonogashira reaction and characterized by NMR, UV–Vis, static and dynamic fluorescence spectroscopy and cyclic voltammetry. The optical and electrochemical properties in solution are consistent with photoinduced energy transfer from the electron donor conjugated backbone to the electron acceptor perylene substituent. Photovoltaic properties are indeed found, even if the performance of the solar cells is quite low due to the formation of aggregates. The incorporation of (6,6)-phenyl C61–butyric acid methyl ester (PCBM), however, increases by an order of magnitude the efficiency of the prototype (from 10⁻⁴ to 10⁻³%) due to both better phase mixing and improved electrical continuity as supported by Atomic Force Microscopy (AFM) and Electrical Force Microscopy (EFM) studies.     

Relatives in the same university faculty: nepotism or merit?

In many countries culture, practice or regulations inhibit the co-presence of relatives within the university faculty. We test the legitimacy of such attitudes and provisions, investigating the phenomenon of nepotism in Italy, a nation with high rates of favoritism. We compare the individual research performance of “children” who have “parents” in the same university against that of the “non-children” with the same academic rank and seniority, in the same field. The results show non-significant differences in performance. Analyses of career advancement show that children’s research performance is on average superior to that of their colleagues who did not advance. The study’s findings do not rule out the existence of nepotism, which has been actually recorded in a low percentage of cases, but do not prove either the most serious presumed consequences of nepotism, namely that relatives who are poor performers are getting ahead of non-relatives who are better performers. In light of these results, many attitudes and norms concerning parental ties in academia should be reconsidered.     

五彩金刚鹦鹉

正"一对金刚鹦鹉停在我视线观察范围内的一棵树上,我因此得以近距离拍摄它们的羽毛。2012年8月摄影师在秘鲁亚马逊Tampopata河的粘土河床附近拍摄了这些照片。五彩金刚鹦鹉原产自南美热带雨林,主要吃水果、坚果和种子,也会定时进食泥土以补充矿物质、促进消化和排出毒素。通常成对活动,飞行时常常伴随刺耳的大叫声。寿命最长可达80年。栖息地破坏以及宠物交易的盗捕,使其生存受到威胁。     

A suite of parallel algorithms for efficient band selection from hyperspectral images

The analysis of hyperspectral images is usually very heavy from the computational point-of-view, due to their high dimensionality. In order to avoid this problem, band selection (BS) has been widely used to reduce the dimensionality before the analysis. The aim is to extract a subset of the original bands of the hyperspectral image, preserving most of the information contained in the original data. The BS technique can be performed by prioritizing the bands on the basis of a score, assigned by specific criteria; in this case, BS turns out in the so-called band prioritization (BP). This paper focuses on BP algorithms based on the following parameters: signal-to-noise ratio, kurtosis, entropy, information divergence, variance and linearly constrained minimum variance. In particular, an optimized C serial version has been developed for each algorithm from which two parallel versions have been derived using OpenMP and NVIDIA’s compute unified device architecture. The former is designed for a multi-core CPU, while the latter is designed for a many-core graphics processing unit. For each version of these algorithms, several tests have been performed on a large database containing both synthetic and real hyperspectral images. In this way, scientists can integrate the proposed suite of efficient BP algorithms into existing frameworks, choosing the most suitable technique for their specific applications.