Self‐nucleation–induced nonisothermal crystallization of nylon 6 from the melt

The effect of thermal treatment over a wide range of temperature (130–280°C) on the crystallization behavior of nylon 6 was studied by using DSC, FTIR, and polarized light microscope equipped with a hot stage. The crystallization and the subsequent melting behavior of the nylon 6 samples treated at different temperatures (T_s) were classified into four types. When T_s was higher than 236°C or lower than 213°C, the crystallization behavior of nylon 6 was insensitive to the variation of T_s. When T_s was in the range of 213–235°C, the crystallization behavior was sensitive to the change of T_s. The polarized light microscopic experiments have demonstrated that a large amount of tiny ordered nylon 6 segments/cluster persisted when nylon 6 film are heated to 231°C. Consequently, the fastest crystallization speed was observed. As T_s was between 214 and 223°C, both the T_m and the ΔH_m were higher than those of the nylon 6 samples treated at other temperature. The polarized light microscopic investigations have also demonstrated that molten nylon 6 crystallizes by using the un‐molten nylon 6 crystals as nucleation center at 220°C. Crystallization at higher temperature produces nylon 6 with thicker crystalline lamella. The above results are helpful for rational design of thermal treatment procedure to obtain nylon 6 with different crystalline features. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42413.     

A Review of “Elderburbia: Aging With a Sense of Place in America”

A problem in applying benefit-cost analysis to planning issues is the difficulty of imputing values to public goods like water quality. During the past thirty years, the contingent valuation (CV) survey method has been institutionalized as a technique for valuing these types of goods. This article traces the development of the method and summarizes recent federal guidelines. Examples from three recent studies, involving willingness to pay for nonpoint-source pollution controls, are used to illustrate issues about the technique. Considerations for planners who must undertake or evaluate CV studies are discussed.     

New Professionalism: the post-industrial context

Definitions and perceptions of professionalism are continually challenged and transformed by public need, government interaction and institutional organizations. When the goals of those three entities are focused on near-term results, this poses a significant threat to the integrity, value and relevance of professional services. When the individual and corporate professional's profit margin, corporate shareholder responsibility and news media sensationalism are factored in, this short-termism dynamic is greatly magnified. Built environment professions are seen as particularly vulnerable to this threat, given that investments in buildings and infrastructure have long-life and high-performance service expectations. This commentary responds to the Building Research & Information special issue entitled ‘New Professionalism’ (2013, volume 40, number 1) and situates the predicament of built environment professionals within an emerging historical transition: that of the post-industrial information society with its characteristic knowledge workers and cybernetic bases of production. Long-term virtues of the built environment mission such as sustainability, public good and evidence-based design are shown to be reflections of the transition from industrial era short-termism to post-industrial systemic foresight. This commentary supplements the special issue papers with a discussion on the broader academy's potential role in breaking the stranglehold of contemporary short-termism in the built environment professions.     

Frank Lloyd Wright and the Concrete Slab and Column

This paper traces the development of Frank Lloyd Wright's ideas on the place of the concrete column and slab in architecture. It deals with his first employment of the slab at Unity Temple (Oak Park, 1904) and his use of the form in residential projects during the next few years. It surveys American literature on concrete construction and briefly analyses the contribution of Claude A.P. Turner and the employment of the Turner system in two Chicago buildings that Wright would have known. It discusses his project for the San Francisco Call (1912) and the use of the Barton system in the Richland Center warehouse for A.D. German (1915). It further discusses his first probable knowledge of the more sophisticated concrete slabs of Maillart, published in 1926, and of Maillart's invention of a proto lily-pad capital. This capital is also to be seen in Wright's champagne glass designed for Leerdam (1930) and in his project for the Salem Capitol Journal of 1931. Finally it is argued that the much admired lily-pad columns at the Johnson Wax office building (Racine, 1937-39) are really a series of three-hinged bents rather than shell construction.     

堆叠式LED结构实现紧凑型多通道光学耦合器

现代光学耦合器的核心是输入端的LED和输出端的光电探测器.它们被绝缘的光传导介质隔开.     

Horizontal transmission of Escherichia coli O157:H7 during cattle housing

Ruminant livestock, particularly cattle, is considered the primary reservoir of Escherichia coli O157:H7. This study examines the transmission of E. coli O157:H7 within groups of cattle during winter housing. Holstein Friesian steers were grouped in six pens of five animals. An animal inoculated with and proven to be shedding a marked strain of E. coli O157: H7 was introduced into each pen. Fecal (rectal swabs) and hide samples (900 cm2 from the right rump) were taken from the 36 animals throughout the study. Water, feed, and gate or partition samples from each pen were also examined. Within 24 h of introducing the inoculated animals into the pens, samples collected from the drinking water, pen barriers, and animal hides were positive for the pathogen. Within 48 h, the hides of 20 (66%) of 30 cohort animals from the six pens were contaminated with E. coli O157:H7. The first positive fecal samples from the noninoculated cohort animals were detected 3 days after the introduction of the inoculated steers. During the 23 days of the study, 15 of 30 cohort animals shed the marked E. coli O157:H7 strain in their feces on at least one occasion. Animal behavior in the pens was monitored during a 12-h period using closed circuit television cameras. The camera footage showed an average of 13 instances of animal grooming in each pen per hour. The study suggests that transmission of E. coli O157:H7 between animals may occur following ingestion of the pathogen at low levels and that animal hide may be an important source of transmission.     

Studies on slag deposit formation in pulverized coal combustors. 1. Results on the wetting and adherence of synthetic coal ash drops on steel

As part of a study of slag deposit formation in pulverized-coal-fired boilers, apparent contact angles and adhesion strengths of molten mineral drops contacted with cooler oxidized steel substrates have been investigated. High-speed photography indicated that freezing of the interface between the molten drop and metal surface occurred in milliseconds. Adherence occurred between an oxide film on the metal and the drop, adherence was weak on stainless steels, and particles of oxide film were broken away from the substrate when the drops were sheared off. Higher substrate temperatures gave increased adhesion, with a larger area of strong interaction between the oxide and the drop interface and less area of weak interaction. Addition of compounds to lower the liquidus temperature of the drop gave increased adherence. Pyrite drops were converted to mainly pyrrhotite on melting and showed a high degree of wetting and adherence to the oxidized steel even at low temperatures.     

DNA‐Scaffolded Multivalent Ligands to Modulate Cell Function

We report a simple, versatile, multivalent ligand system that is capable of specifically and efficiently modulating cell‐surface receptor clustering and function. The multivalent ligand is made of a polymeric DNA scaffold decorated with biorecognition ligands (i.e., antibodies) to interrogate and modulate cell receptor signaling and function. Using CD20 clustering‐mediated apoptosis in B‐cell cancer cells as a model system, we demonstrated that our multivalent ligand is significantly more effective at inducing apoptosis of target cancer cells than its monovalent counterpart. This multivalent DNA material approach represents a new chemical biology tool to interrogate cell receptor signaling and functions and to potentially manipulate such functions for the development of therapeutics.