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Confined Spaces

Yuan-Hsin Cheng, William E Field, Salah F Issa, Kevin Kelley, Matthew Heber, Robert Turner
Since 1978, the Purdue University Agricultural Safety and Health Program has managed a surveillance effort and database to collect information on documented injuries and fatalities in all forms of U.S. agricultural confined spaces. The database currently contains 1,968 cases documented in the U.S. between 1964 and 2016. Of these cases, 174 (8.8%) involved entrapment or suffocation in grain transport vehicles (GTVs), including gravity-flow wagons, semi-truck trailers, and other agricultural transport vehicles that have limited access and are not considered normal work spaces or are classified as confined spaces...
May 7, 2018: Journal of Agricultural Safety and Health
Salah F Issa, Mahmoud M Nour, William E Field
No previous studies have been found that document the level of use or validate the effectiveness of safety harnesses and lifelines in the prevention of or extrication from grain entrapments or engulfments. This article addresses that void via analysis of the data contained in the Purdue Agricultural Confined Space Incident Database. A total of 1,147 cases involving entrapments or engulfments in grain masses were mined for terms that might indicate the use of a safety harness, lifeline, fall restraint system, rope, or outside observer...
May 7, 2018: Journal of Agricultural Safety and Health
Yingfeng Li, Mengqi Cui, Bo Peng, Mingde Qin
Understanding the adsorption behaviors of supercritical fluid in confined space is pivotal for coupling the supercritical technology and the membrane separation technology. Based on grand canonical Monte Carlo simulations, the adsorption behaviors of a Lennard-Jones (LJ) fluid in slit-like pores at reduced temperatures over the critical temperature, Tc *  = 1.312, are investigated; and impacts of the wall-fluid interactions, the pore width, and the temperature are taken into account. It is found that even if under supercritical conditions, the LJ fluid can undergo a "vapor-liquid phase transition" in confined space, i...
May 18, 2018: Journal of Molecular Graphics & Modelling
Lynne Cassimeris, Jessica C Leung, David J Odde
Microtubules are dynamic polymers required for a number of processes, including chromosome movement in mitosis. While regulators of microtubule dynamics have been well characterized, we lack a convenient way to predict how the measured dynamic parameters shape the entire microtubule system within a cell, or how the system responds when specific parameters change in response to internal or external signals. Here we describe a Monte Carlo model to simulate an array of dynamic microtubules from parameters including the cell radius, total tubulin concentration, microtubule nucleation rate from the centrosome, and plus end dynamic instability...
2018: PloS One
Lin Zhang, Haoting Tian, Ran Hong, Chao Wang, Yi Wang, Anping Peng, Cheng Gu
Atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) is a commonly used agricultural herbicide that, as a result, is frequently detected in surface and ground water. In this study, we provide evidence of the photo-oxidation of atrazine under environmentally relevant conditions, specifically, in the presence of natural montmorillonite clay and the ubiquitous phytohormone indole-3-acetic acid (IAA). The reaction is initiated by the generation of hydrated electrons from the photo-ionization of IAA. These electrons react with protons and dissolved oxygen to form hydroxyl radicals, which promote the further degradation of atrazine...
May 17, 2018: Environmental Pollution
Hang Zhang, Qiuming Gao, Weiwei Qian, Hong Xiao, Zeyu Li, Li Ma, Xuehui Tian
N, O-codoped hierarchical porous nanocomposite consisted of binary reduced graphene oxide and pyrolytic carbon from chitosan (rGO/PC) is fabricated. The optimized rGO/PC possesses micropores with size distribution concentrated around 1.1 nm and plenty of meso/macropores. The BET specific surface area is 480.8 m2 g-1, and impressively large pore volume of 2.14 cm3 g-1. Based on the synergistic effects of the following main factors: (i) the confined space effect in the hierarchical porous binary carbonaceous matrix, (ii) the anchor effects by strong chemical bonds with codoped N and O atoms; and (iii) the good flexibility and conductivity of rGO, the rGO/PC/S holding 75 wt...
May 15, 2018: ACS Applied Materials & Interfaces
Xiuqing Duan, Zhenwei Yao
Knotted fields enrich a variety of physical phenomena, ranging from fluid flows, electromagnetic fields, to textures of ordered media. Maxwell's electrostatic equations, whose vacuum solution is mathematically known as a harmonic field, provide an ideal setting to explore the role of domain topology in determining physical fields in confined space. In this work, we show the uniqueness of a harmonic field in knotted tubes, and reduce the construction of a harmonic field to a Neumann boundary value problem. By analyzing the harmonic field in typical knotted tubes, we identify the torsion driven transition from bipolar to vortex patterns...
April 2018: Physical Review. E
Benaoumeur Bakhti, Divana Boukari, Michael Karbach, Philipp Maass, Gerhard Müller
We consider a lattice gas in spaces of dimensionality D=1,2,3. The particles are subject to a hardcore exclusion interaction and an attractive pair interaction that satisfies Gauss' law as do Newtonian gravity in D=3, a logarithmic potential in D=2, and a distance-independent force in D=1. Under mild additional assumptions regarding symmetry and fluctuations we investigate equilibrium states of self-gravitating material clusters, in particular radial density profiles for closed and open systems. We present exact analytic results in several instances and high-precision numerical data in others...
April 2018: Physical Review. E
M D Campanell
It is widely assumed that thermionic current flow through a plasma is limited by a "space-charge-limited" (SCL) cathode sheath that consumes the hot cathode's negative bias and accelerates upstream ions into the cathode. Here, we formulate a fundamentally different current-limited mode. In the "inverse" mode, the potentials of both electrodes are above the plasma potential, so that the plasma ions are confined. The bias is consumed by the anode sheath. There is no potential gradient in the neutral plasma region from resistivity or presheath...
April 2018: Physical Review. E
Xiewen Wen, Hailong Chen, Tianmin Wu, Zhihao Yu, Qirong Yang, Jingwen Deng, Zhengtang Liu, Xin Guo, Jianxin Guan, Xiang Zhang, Yongji Gong, Jiangtan Yuan, Zhuhua Zhang, Chongyue Yi, Xuefeng Guo, Pulickel M Ajayan, Wei Zhuang, Zhirong Liu, Jun Lou, Junrong Zheng
Phase transitions of electron-hole pairs on semiconductor/conductor interfaces determine fundamental properties of optoelectronics. To investigate interfacial dynamical transitions of charged quasiparticles, however, remains a grand challenge. By employing ultrafast mid-infrared microspectroscopic probes to detect excitonic internal quantum transitions and two-dimensional atomic device fabrications, we are able to directly monitor the interplay between free carriers and insulating interlayer excitons between two atomic layers...
May 10, 2018: Nature Communications
Kiwoong Seong, Kyuyup Lee, Sunil Puria, Jin-Ho Cho
Many clinical reports have discussed the effectiveness of stimulating the ear's round window (RW) with a tool to mitigate conductive and mixed hearing loss. The RW is one of the two openings from the middle ear into the inner ear. Various methods have been proposed to construct a highly efficient, easily implanted, and reliable RW transducer. Devices, however, such as floating mass transducers, have difficulty establishing proper contact without some degree of bone incision around the RW. Additionally, vibration energy may not be fully transmitted to the cochlea, but instead will be spread through the soft tissue around the transducer...
May 2, 2018: Computers in Biology and Medicine
Cedric J Gommes, Anthony P Roberts
Most mesoporous materials of practical interest are inherently disordered, which has a significant impact on the condensation and evaporation of vapours in their pores. Traditionally, the effect of disorder is theoretically analyzed in a perturbative approach whereby slight elements of disorder (constriction, corrugation) are added to geometrically ideal pores. We propose an alternative approach, which consists of using a stochastic geometrical model to describe both the porous material and the condensate within the pores...
May 8, 2018: Physical Chemistry Chemical Physics: PCCP
A P Yang, L P Du, F F Meng, X C Yuan
Electromagnetic fields at near-field exhibit distinctive properties with respect to their free-space counterparts. In particular, an optical transverse spin appearing in a confined electromagnetic field provides the foundation for many intriguing physical effects and applications. We present a transverse spin coupling configuration where plasmonic nanoparticles are employed to couple the transverse spin in a focused beam to that of a surface plasmon polariton. The plasmonic resonance of nanoparticles on a metal film plays a significant role in transverse spin coupling...
May 8, 2018: Nanoscale
Yuichiro Ukon, Takaaki Tanaka, Shigenori Nagata, Hiroki Hagizawa, Yoshinori Imura, Hironari Tamiya, Kazuya Oshima, Norifumi Naka, Yasuaki Aoki, Shigeyuki Kuratsu
Calcific myonecrosis is a rare soft tissue condition. The first case was reported in 1960, however, the precise pathophysiology of calcific myonecrosis remains unclear. The disease was thought to arise from compartment syndrome within a confined space resulting in necrosis and fibrosis, subsequent repeated intralesional hemorrhage, mass enlargement and calcification. Several previous reports have described calcific myonecrosis, which include the formation of calcific myonecrosis after a prolonged period of post trauma...
May 2018: Oncology Letters
Takahiro Sakaue
We analyze the behavior of a semiflexible polymer confined in nanochannel under compression in axial direction. Key to our discussion is the identification of two length scales; the correlation length $\xi$ of concentration fluctuation and what we call the {\it segregation length} $\xi_w$. These length scales, while degenerate in uncompressed state in nanochannel, generally split as $\xi < \xi_w$ upon compression, and the way they compete with the system size during the compression determines the crossover from quasi one-dimensional (quasi-1-d) nanochannel to quasi-0-d nanocavity behaviors...
May 4, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Jing-Yan Liu, Shi-Yong Zhang, Ying Zeng, Xia Shu, Zi-Yi Du, Chun-Ting He, Wei-Xiong Zhang, Xiao-Ming Chen
Dielectric switches that can be converted between high and low dielectric states by thermal stimuli have attracted much interest owing to their many potential applications. Currently one main drawback for practical application lies in the non-tunability of their switch temperatures (TS). We report here an ionic co-crystal (Me3NH)4[Ni(SCN)6] that contains a multiply rotatable Me3NH+ ion and a solely rotatable one due to a more spacious supramolecular cage for the former one. This compound undergoes an isostructural order-disorder phase transition and it can function as a frequency-tuned dielectric switch with highly adjustable TS, which is further revealed by the variable-temperature structure analyses and molecular dynamics simulations...
May 3, 2018: Angewandte Chemie
Atsushi Sakai, Yoshihiro Murayama, Kei Fujiwara, Takahiro Fujisawa, Saori Sasaki, Satoru Kidoaki, Miho Yanagisawa
Even though microgels are used in a wide variety of applications, determining their mechanical properties has been elusive because of the difficulties in analysis. In this study, we investigated the surface elasticity of a spherical microgel of gelatin prepared inside a lipid droplet by using micropipet aspiration. We found that gelation inside a microdroplet covered with lipid membranes increased Young's modulus E toward a plateau value E * along with a decrease in gel size. In the case of 5.0 wt % gelatin gelled inside a microsized lipid space, the E * for small microgels with R ≤ 50 μm was 10-fold higher (35-39 kPa) than that for the bulk gel (∼3 kPa)...
April 25, 2018: ACS Central Science
Zengjun Jin, Mengyue Nie, Ran Hu, Tianhu Zhao, Jingyue Xu, Dongwei Chen, Juanli Yun, Luyan Z Ma, Wenbin Du
Bacterial biofilms play essential roles in biogeochemical cycling, degradation of environmental pollutants, infection diseases, and maintenance of host health. The lack of quantitative methods for growing and characterizing biofilms remains a major challenge in understanding biofilm development. In this study, a dynamic sessile-droplet habitat is introduced, a simple method which cultivates biofilms on micropatterns with diameters of tens to hundreds of micrometers in a microfluidic channel. Nanoliter plugs are utilized, spaced by immiscible carrier oil to initiate and support the growth of an array of biofilms, anchored on and spatially confined to the micropatterns arranged on the bottom surface of the microchannel, while planktonic or dispersal cells are flushed away by shear force of aqueous plugs...
May 2, 2018: Small
Yige Zhao, Chen Wang, Jingjun Liu, Feng Wang
Structurally ordered intermetallic alloys with definite composition and distinct structure show great potential as electro-catalysts for the oxygen reduction reaction (ORR). However, their fabrication with small particle size remains a challenge since grain growth caused by high temperature annealing is unavoidable for the formation of the ordered phase. Here we propose an effective space-confined strategy to prepare an intermetallic alloy with small size (CoPt3/C-S) through annealing of the disordered Pt-Co alloy coated with polydopamine (PDA)...
May 2, 2018: Nanoscale
Dipak Samanta, Julius Gemen, Zonglin Chu, Yael Diskin-Posner, Linda J W Shimon, Rafal Klajn
Efficient molecular switching in confined spaces is critical for the successful development of artificial molecular machines. However, molecular switching events often entail large structural changes and therefore require conformational freedom, which is typically limited under confinement conditions. Here, we investigated the behavior of azobenzene-the key building block of light-controlled molecular machines-in a confined environment that is flexible and can adapt its shape to that of the bound guest. To this end, we encapsulated several structurally diverse azobenzenes within the cavity of a flexible, water-soluble coordination cage, and investigated their light-responsive behavior...
May 1, 2018: Proceedings of the National Academy of Sciences of the United States of America
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