3,848 research outputs found
Tribo-corrosion of steel in artificial saliva
Stainless steel is widely used as dental implant. However, there has been little work on the micro-abrasion of such materials in laboratory simulated oral environments, where abrasion, sliding wear can interact simultaneously. In this study, the effects of applied load, and exposure time were evaluated for a 316 stainless steel in a laboratory simulated artificial saliva. Polarization curves showed an enhancement of corrosion current density with increases in applied load. Wear maps were produced showing low wear safety regimes at intermediate loads and exposure times. Possible reasons for such trends are interpreted in terms of the ability of the passive film in providing resistance against third body particle impact and the concentration of particles in the contact at higher loads
Design of Adiabatic MTJ-CMOS Hybrid Circuits
Low-power designs are a necessity with the increasing demand of portable
devices which are battery operated. In many of such devices the operational
speed is not as important as battery life. Logic-in-memory structures using
nano-devices and adiabatic designs are two methods to reduce the static and
dynamic power consumption respectively. Magnetic tunnel junction (MTJ) is an
emerging technology which has many advantages when used in logic-in-memory
structures in conjunction with CMOS. In this paper, we introduce a novel
adiabatic hybrid MTJ/CMOS structure which is used to design AND/NAND, XOR/XNOR
and 1-bit full adder circuits. We simulate the designs using HSPICE with 32nm
CMOS technology and compared it with a non-adiabatic hybrid MTJ/CMOS circuits.
The proposed adiabatic MTJ/CMOS full adder design has more than 7 times lower
power consumtion compared to the previous MTJ/CMOS full adder
Evaluation of QSAR and ligand enzyme docking for the identification of ABCB1 substrates
P-glycoprotein (P-gp) is an efflux pump that belongs to ATP-binding cassette (ABC) transporter family embedded in the membrane bilayer. P-gp is a polyspecific protein that has demonstrated its function as a transporter of hydrophobic drugs as well as transporting lipids, steroids and metabolic products. Its role in multidrug resistance (MDR) and pharmacokinetic profile of clinically important drug molecules has been widely recognised. In this study, QSAR and enzyme-ligand docking methods were explored in order to classify substrates and non-substrates of P-glycoprotein. A set of 123 compounds designated as substrates (54) or non-substrates (69) by Matsson et al., 2009 was used for the investigation. For QSAR studies, molecular descriptors were calculated using ACD labs/LogD Suite and MOE (CCG Inc.). P-glycoprotein structures available in the Protein data bank were used for docking studies and determination of binding scores using MOE software. Binding sites were defined using co-crystallised ligand structures. Three classification algorithms which included classification and regression trees, boosted trees and support vector machine were examined. Models were developed using a training set of 98 compounds and were validated using the remaining compounds as the external test set. A model generated using BT was identified as the best of three models, with a prediction accuracy of 88%, Mathews correlation coefficient of 0.77 and Youden’s J index of 0.80 for the test set. Inclusion of various docking scores for different binding sites improved the models only marginally
On LDPC Codes for Gaussian Interference Channels
In this paper, we focus on the two-user Gaussian interference channel (GIC),
and study the Han-Kobayashi (HK) coding/decoding strategy with the objective of
designing low-density parity-check (LDPC) codes. A code optimization algorithm
is proposed which adopts a random perturbation technique via tracking the
average mutual information. The degree distribution optimization and
convergence threshold computation are carried out for strong and weak
interference channels, employing binary phase-shift keying (BPSK). Under strong
interference, it is observed that optimized codes operate close to the capacity
boundary. For the case of weak interference, it is shown that via the newly
designed codes, a nontrivial rate pair is achievable, which is not attainable
by single user codes with time-sharing. Performance of the designed LDPC codes
are also studied for finite block lengths through simulations of specific codes
picked from the optimized degree distributions.Comment: ISIT 201
Chemical composition and antifungal effects of three species of Satureja (S. hortensis, S. spicigera, and S. khuzistanica) essential oils on the main pathogens of strawberry fruit
Due to an increasing risk of chemical contamination upon the application of synthetic fungicides to preserve fresh fruits and vegetables, essential oils are gaining increasing attentions. In this research, besides chemical analysis of the essential oils of three Satureja species (S. hortensis, S. spicigera, and S. khuzistanica) by GC-MS, their fungicidal and/or fungistatic effects on postharvest pathogens of strawberry were investigated. Essential oils were extracted by means of hydro-distillation and afterwards GC/MS analysis was performed to identify their components. Carvacrol, γ-terpinene and p-cymene were detected as the repeating main constituents of the spices, while thymol and carvacrol methyl ether were found as major components only in S. spicigera oil. In vitro results showed that at the maximum concentration, the essential oils did not possess fungicidal effects on Aspergillus niger but they exhibited fungicidal activities against Penicillium digitatum, Botrytis cinerea and Rhizopus stolonifer. However, S. khuzistanica was the strongest oil in fungicidal activity. S. hortensis oil was more effective than S. spicigera against B. cinerea whereas S. spicigera oil showed stronger fungicidal activity against R. stolonifer. In conclusion, essential oils isolated from three savory species could be suitable for applications in the food industry to control molds and improve the safety of fruits and vegetables. © 2015 Elsevier B.V
The pattern of Caspian Sea water penetration into Anzali Wetland: Introduction of a salt wedge
Measuring salinity of water at different depths along six transacts at the mouth of the wetland and along five tributaries connecting the wetland to the sea the extent of Caspian Sea penetration into Anzali Wetland was determined. The results demonstrated a depth-dependent salinity gradient extending up to 10 kilometres into the wetland. A pattern of saltwater and freshwater interface is presented and the role of this interface in enhancing sedimentation is discussed
Clouds of Small Things: Provisioning Infrastructure-as-a-Service from within Community Networks
Community networks offer a shared communication infrastructure where communities of citizens build and own open networks. While the IP connectivity of the networking devices is successfully achieved, the number of services and applications available from within the community network is typically small and the usage of the community network is often limited to providing Internet access to remote areas through wireless links. In this paper we propose to apply the principle of resource sharing of community networks, currently limited to the network bandwidth, to other computing resources, which leads to cloud computing in community networks. Towards this vision, we review some characteristics of community networks and identify potential scenarios for community clouds. We simulate a cloud computing infrastructure service and discuss different aspects of its performance in comparison to a commercial centralized cloud system. We note that in community clouds the computing resources are heterogeneous and less powerful, which affects the time needed to assign resources. Response time of the infrastructure service is high in community clouds even for a small number of resources since resources are distributed, but tends to get closer to that of a centralized cloud when the number of resources requested increases. Our initial results suggest that the performance of the community clouds highly depends on the community network conditions, but has some potential for improvement with network-aware cloud services. The main strength compared to commercial cloud services, however, is that community cloud services hosted on community-owned resources will follow the principles of community network and will be neutral and open
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