In situ electronic characterization of graphene nanoconstrictions fabricated in a transmission electron microscope

We report electronic measurements on high-quality graphene nanoconstrictions (GNCs) fabricated in a transmission electron microscope (TEM), and the first measurements on GNC conductance with an accurate measurement of constriction width down to 1 nm. To create the GNCs, freely suspended graphene ribbons were fabricated using few-layer graphene grown by chemical vapor deposition. The ribbons were loaded into the TEM, and a current-annealing procedure was used to clean the material and improve its electronic characteristics. The TEM beam was then used to sculpt GNCs to a series of desired widths in the range 1-700 nm; after each sculpting step, the sample was imaged by TEM and its electronic properties were measured in situ. GNC conductance was found to be remarkably high, comparable to that of exfoliated graphene samples of similar size. The GNC conductance varied with width approximately as G(w)=(e2/h)w0.75, where w is the constriction width in nanometers. GNCs support current densities greater than 120 μA/nm2, 2 orders of magnitude higher than that which has been previously reported for graphene nanoribbons and 2000 times higher than that reported for copper.     

Design Fire Characteristics for Probabilistic Assessments of Dwellings in England

In England, there are no fixed requirements on the parameters adopted when considering residential design fires, and analyses undertaken are often deterministic with limited consideration given to probabilistic assessments and the sensitivity of parameters. The Home Office dwelling fires dataset has been analysed, considering the fire damage area and the time from ignition to fire and rescue service arrival. From this, lognormal distributions for the maximum heat release rate (HRR) and fire growth rate of residential fires have been approximated. The mean maximum HRR ranges from 900 kW to 1900 kW, with a standard deviation ranging from 2000 kW to 3700 kW, depending on property type and room of fire origin. The mean growth rate, assuming a t2 relationship, ranges from 0.0022 kW/s2 to 0.0034 kW/s2, with a standard deviation ranging from 0.0071 kW/s2 to 0.0132 kW/s2. When considering incidents which result in immediate fire and rescue service call out following ignition, the mean growth rate increases to a range of 0.0058 kW/s2 to 0.0088 kW/s2. As a result of the analyses, design fire distributions are provided which can be adopted for probabilistic assessments. For deterministic analyses, it is proposed that an approximate 95th percentile fire may be adopted, aligning with a medium growth rate of 0.0117 kW/s2 and a maximum fuel-limited HRR in the region of 3800 kW to 4400 kW, depending on whether the dwelling is a house or an apartment. A 95th percentile design fire broadly aligns with values already specified in guidance, helping to substantiate the existing recommendations.     

Shennan Road and the modernization of Shenzhen architecture

Shenzhen exemplifies the rapid development of urban planning and construction in China. Over the last 40 years, many representative urban spaces and buildings have been built on Shennan Road, the city's main east–west thoroughfare, which has witnessed the formation of a multicenter structural layout and the miraculous expansion of the city. Many iconic buildings were designed by Hong Kong or foreign architects. The continuous development along Shennan Road not only symbolizes the fruits of the reform and opening up policies of Shenzhen and even China, but also reflects the modern architectural history in Shenzhen. This study uses historical research methods to review the changes in the urban fabric and the design trends, as seen in representative buildings along Shennan Road in different periods. In addition to the transition path of the city center, the unique role of streets and buildings in the development of the urban structure is analyzed, and other urban functions and symbolic meanings are identified. This work contributes to the history and theory of the modernization of contemporary Chinese architecture.     

海外设计在中国(1978～2010)

我国的改革开放已经走过30多个年头外国建筑设计随着国门和经济开放涌入我国,对我国的城市景观和建筑业造成极大冲击和影响,这种冲击和影响有正面的也有负面的中国的外国建筑设计成了东方与西方,外国与中国科技文化论题的交汇点简要回顾30年来输入海外建筑设计的历程井讨论由此带来的各种现象和问题     

Reduction of off-flavor generation in soybean homogenates: a mathematical model

The generation of off-flavors in soybean homogenates such as n-hexanal via the lipoxygenase (LOX) pathway can be a problem in the processed food industry. Previous studies have examined the effect of using soybean varieties missing one or more of the 3 LOX isozymes on n-hexanal generation. A dynamic mathematical model of the soybean LOX pathway using ordinary differential equations was constructed using parameters estimated from existing data with the aim of predicting how n-hexanal generation could be reduced. Time-course simulations of LOX-null beans were run and compared with experimental results. Model L(2), L(3), and L(12) beans were within the range relative to the wild type found experimentally, with L(13) and L(23) beans close to the experimental range. Model L(1) beans produced much more n-hexanal relative to the wild type than those in experiments. Sensitivity analysis indicates that reducing the estimated K(m) parameter for LOX isozyme 3 (L-3) would improve the fit between model predictions and experimental results found in the literature. The model also predicts that increasing L-3 or reducing L-2 levels within beans may reduce n-hexanal generation. PRACTICAL APPLICATION: This work describes the use of mathematics to attempt to quantify the enzyme-catalyzed conversions of compounds in soybean homogenates into undesirable flavors, primarily from the compound n-hexanal. The effect of different soybean genotypes and enzyme kinetic constants was also studied, leading to recommendations on which combinations might minimize off-flavor levels and what further work might be carried out to substantiate these conclusions.     

IFC implementation in lifecycle costing

Life Cycle Costing (LCC) is always a major concern in the Architecture, Engineering and Construction (AEC) industry. This paper presents the implementation of Building Information Modeling (BIM) technotogy in the development of a lifecycle cost-estimating tool. The IFC ( Industry Foundation Classes) model as an interoperable building information model has been adopted as the central data repository to deliver the integrated information of building designs from CAD design systems into the lifecycle-costing database. In this paper, the conceptions and relevant factors, which could affect the LCC estimation, bare been introdueed. The problems of current LCC applications have been identified as the lack of LCC data and the complexity of LCC exercises. The software application of IFC models and relevant auxiliary are depicted as a solution of the problem identified. The lifecycle eosting tool is a part of the nD Modeling tool and as such is based on its integrated interface prototype toolkit and is able to holisticallv present an IFC model into a 3D virtual reality view, a tree-view and a list of element properties. The functions and some technical points are also detailed in the paper. Through the research, it demonstrates the potential and possibility of implementing BIM methods and techniques, particularly IFCs to enhance the computer applications in the processes of building eonstruction and facility management.     

Enhanced Mechanical Properties and Thermal Stability of Accumulative Roll-Bonded Cu/Nb Multilayer Composites via Cryorolling

Metallurgical and Materials Transactions A - Accumulative roll-bonded(ARB) Cu/Nb multilayer composites were cryorolled and room-temperature rolled. The ultimate tensile stress of ARB composite...