High‐Performance Transition Metal Dichalcogenide Photodetectors Enhanced by Self‐Assembled Monolayer Doping

Most doping research into transition metal dichalcogenides (TMDs) has been mainly focused on the improvement of electronic device performance. Here, the effect of self‐assembled monolayer (SAM)‐based doping on the performance of WSe₂‐ and MoS₂‐based transistors and photodetectors is investigated. The achieved doping concentrations are ≈1.4 × 10¹¹ for octadecyltrichlorosilane (OTS) p‐doping and ≈10¹¹ for aminopropyltriethoxysilane (APTES) n‐doping (nondegenerate). Using this SAM doping technique, the field‐effect mobility is increased from 32.58 to 168.9 cm² V^?1 s in OTS/WSe₂ transistors and from 28.75 to 142.2 cm² V^?1 s in APTES/MoS₂ transistors. For the photodetectors, the responsivity is improved by a factor of ≈28.2 (from 517.2 to 1.45 × 10⁴ A W^?1) in the OTS/WSe₂ devices and by a factor of ≈26.4 (from 219 to 5.75 × 10³ A W^?1) in the APTES/MoS₂ devices. The enhanced photoresponsivity values are much higher than that of the previously reported TMD photodetectors. The detectivity enhancement is ≈26.6‐fold in the OTS/WSe₂ devices and ≈24.5‐fold in the APTES/MoS₂ devices and is caused by the increased photocurrent and maintained dark current after doping. The optoelectronic performance is also investigated with different optical powers and the air‐exposure times. This doping study performed on TMD devices will play a significant role for optimizing the performance of future TMD‐based electronic/optoelectronic applications.     

Measurement of heat/mass transfer at second stage vane endwall according to step heights

Journal of Mechanical Science and Technology - Recently, domestic gas turbines are primarily operated under partial loads. Hence, thermal expansion of components decreases, leading to a...     

Wi‐Fi‐based modeling and hybrid routing scheme for delay‐tolerant public bus network

Delay‐ or Disruption‐Tolerant Networking (DTN) is a communications approach that is utilized in easily disrupted or delayed networks. Examples of such networks are often found in heterogeneous networks, mobile or extreme terrestrial networks, and planned networks in space. In this paper, we examine the metropolitan bus network as a research target of DTN for a public transport network. We analyze the metropolitan bus network through spatial and temporal modeling using an existing Bus Information System (BIS) database. On the basis of the results of our analysis, we propose and design an appropriate DTN routing scheme called Hybrid Position‐based DTN Routing. This scheme uses position‐based routing instead of address‐based routing by soliciting infrastructural help from nearby Access Points for the real‐time BIS location service. We simulated our scheme using a WLAN for the wideband DTN communication and evaluated it by comparing it with traditional Ad hoc flooding, Epidemic routing, and strategic protocol steps in our own algorithm. The results indicate that our scheme achieves reasonably high performance in terms of packet delivery ratio, latency, and resource usage. Copyright © 2013 John Wiley & Sons, Ltd.     

Bacterial inactivation in water,DNA strand breaking,and membrane damage induced by ultraviolet-assisted titanium dioxide photocatalysis

The effects of UV-assisted TiO₂-photocatalytic oxidation (PCO) inactivation of pathogenic bacteria (Escherichia coli O157:H7, Listeria monocytogenes, Salmonella typhimurium) in a liquid culture using different domains of UV irradiation (A, B and C) were evaluated. Structural changes in super-coiled plasmid DNA (pUC19) and genomic DNA of E. coli were observed using gel electrophoresis to demonstrate the photodynamic DNA strand breaking activity of UV-assisted TiO₂-PCO. Membrane damage in bacterial cells was observed using both a scanning electron microscope (SEM) and a confocal laser scanning microscope (CLSM). Both UVC-TiO₂-PCO and UVC alone resulted in an earlier bactericidal phase (initial counts of approximately 6 log CFU/mL) in 60 s and 90 s, respectively, in liquid culture. UVC-TiO₂-PCO treatment for 6 min converted all plasmid DNA to the linear form; however, under UVC irradiation alone, super-coiled DNA remained. Prolonged UVC-TiO₂-PCO treatment resulted in structural changes in genomic DNA from E. coli. SEM observations revealed that bacteria suffered severe visible cell damage after UVC-TiO₂-PCO treatment for 30–60 min. S. typhimurium cells showed visible damage after 30 min, which was confirmed using CLSM. All treated cells were stained red using propidium iodide under a fluorescent light.     

Applying direct digital control

One particular aspect of a wide range of HVAC research at the US Center for Building Technology concerned interfacing DDC with the pneumatic system for one of the existing air handling units at the CBT building itself. Using solenoid air valves induced both positive and negative air leaks in the pneumatic system; this did not occur with motorised pressure regulators, though these produced a time delay whenever the regulator's direction of rotation was reversed. Details are given of an adaptive PI algorithm with a self‐tuning regulator approach, developed at CBT and implemented on the air handler in question. From the experience, it is strongly recommended that such an algorithm should be implemented on a positional basis.     

R. M. Schindler's theory of space architecture and its theoretical application to his Space Development of 1945

Rudolph Michael Schindler has been known as the first and foremost space architect, in his own words, whose devotion to space as defining architecture remained vital and remarkably consistent throughout his professional career. The purpose of this article is systematically to interpret Schindler's theory of space architecture, and then to discuss his theoretical project: Space Development. The first part investigates Schindler's underlying forms of conception. For Schindler, forms of architecture begin with the space architect's process of thinking, shaping, and feeling the building in the mind. Using a recently uncovered series of Schindler's 1916 lecture notes, from the Schindler archive at the University of California, Santa Barbara (UCSB), the investigation presents a new and critical examination of his theory. The second part interprets his theoretical project, Space Development, to strengthen the understanding of Schindler's notion of space architecture. Along with Space Development, Schindler also evolved two related projects in the same year, sharing the same compositional logic. This article further examines the spatial paradigm pertinent to his Space Development, investigates its relationship to two other designs, and demonstrates how his design theory became further clarified and strengthened through it in the final phase of his career.     

Moving average correction method for compensation of differential column shortenings in high‐rise buildings

The differential length changes of vertical members in a high‐rise building due to elastic, creep and shrinkage shortenings are of primary concern since the differential shortening of the vertical members causes unexpected damages on structural and nonstructural members. In contrast to researches on prediction methods for calculation of the amount of the shortenings, only few methods or algorithms of compensation of the differential column shortenings have been reported. In this paper, a practical compensation method using moving average correction is presented. The proposed method is applied to the compensation of the differential shortenings of the vertical members in a 70‐story high‐rise building. The performance of the moving average correction method is compared with the optimal compensation method based on simulated annealing algorithm. It is demonstrated that the magnitude of the differential shortening or the degree of the slab tilt due to the length changes in the vertical members can be controlled without using structural optimization techniques. Copyright © 2011 John Wiley & Sons, Ltd.     

Geometric nonlinear analysis of tall building structures with outriggers

In this paper, the geometric nonlinear behavior of wall‐frame tall building structures is analyzed. The governing equations of the wall‐frame systems with outrigger trusses are formulated through the continuum approach, and the whole structure is idealized as a shear‐flexural cantilever with rotational spring. The effect of shear and flexural deformation of the wall frame and outrigger trusses are considered and incorporated in the formulation of the governing equations. Geometric nonlinearity in the sense of von Karman is included in the formulation, and Newton–Raphson iterative method is employed to solve the nonlinear equations. A displacement‐based one‐dimensional nonlinear finite element model is developed. Numerical results for wall frame and mega‐column structures with outriggers are obtained and compared with the finite element package MIDAS. The proposed method is found to be simple and efficient, providing reasonably accurate results in early design stages of tall building structures. Copyright © 2011 John Wiley & Sons, Ltd.     

Optimizations and heat integrations on the separation of toluene and 1-butanol azeotropic mixture by pressure swing distillation

In this study, optimizations on separation of Toluene and 1-Butanol mixture is carried out by pressure swing distillation process. New heat integration methods are applied and compared to conventional PSD process by using vapor recompression technique combined with pressure swing distillation process. New heat integration methods show positive results to decrease the utilities used in the process. A simulator Aspen HYSYS V8.4 is used for simulating all processes. Cost analysis is also performed and Aspen HYSYS V8.4 optimizer program is used for optimizing profit for the process. Pressure is also optimized for minimum heat duty requirements in the process and the ultimate concern is to minimize the total reboiler heat duties and overall operating cost for the system which results into increasing profit.     

Bio-electrochemical conversion of atmospheric N<Subscript>2</Subscript> to ammonium using free-living diazotrophs

The effects of electrochemical reducing power on enrichment, growth, and ammonium production of freeliving diazotrophs from rhizosphere soil were evaluated. Soil bacteria were cultivated in a conventional bioreactor (CBR) and an electrochemical bioreactor (EBR), both containing a neutral red-modified graphite felt (NR-GF) cathode and a platinum anode, but with electricity charged to the EBR only. Temperature gradient gel electrophoresis identified 21 species from rhizosphere soil, and 17 and seven species from the CBR and EBR, respectively, after 40 days of incubation. Six species from the CBR and five species from the EBR were diazotrophs. The bacterial community biomass and the ammonium content in the bacterial culture were, respectively, 1.6 and 2 times higher in the EBR than in the CBR. These results indicate that the electrochemical reducing power generated from the NR-GF may be a driving force in the activation of enrichment, growth, and N₂-fixing metabolism of diazotrophs.