913 research outputs found
Removal of mercury (II) from aqueous solution by using rice residues
Sorption potential of rice residues for Hg(II) removal from aqueous solution was investigated. Rice husk (RH) and rice straw (RS) were selected and treated with sodium hydroxide (NaOH). The raw and modified adsorbents were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and BET surface area measurements. The effects of pH, initial ion concentration, and agitation time on the removal process were studied in batch adsorption experiments. Two simple kinetic models, which are pseudo-first-order and pseudo-second-order, were tested to investigate the adsorption mechanisms. The kinetic data fits to pseudo second order model with correlation coefficients greater than 0.99 for all adsorbents. The equilibrium data fitted well with the Langmuir compared to Freundlich isotherm models. Alkali-treated adsorbent obtained larger surface area and RH-NaOH showed highest adsorption capacity followed by RS-Pure > RH-Pure > RS-NaOH. The maximum removal efficiency obtained by RH-NaOH and RS-Pure was 42 mg/l (80%) at pH 6.5 and with 2 days contact time (for 50 mg/l initial concentration and 25 mg adsorbents)
Charge and momentum transfer in supercooled melts: Why should their relaxation times differ?
The steady state values of the viscosity and the intrinsic ionic-conductivity
of quenched melts are computed, in terms of independently measurable
quantities. The frequency dependence of the ac dielectric response is
estimated. The discrepancy between the corresponding characteristic relaxation
times is only apparent; it does not imply distinct mechanisms, but stems from
the intrinsic barrier distribution for -relaxation in supercooled
fluids and glasses. This type of intrinsic ``decoupling'' is argued not to
exceed four orders in magnitude, for known glassformers. We explain the origin
of the discrepancy between the stretching exponent , as extracted from
and the dielectric modulus data. The actual width of the
barrier distribution always grows with lowering the temperature. The contrary
is an artifact of the large contribution of the dc-conductivity component to
the modulus data. The methodology allows one to single out other contributions
to the conductivity, as in ``superionic'' liquids or when charge carriers are
delocalized, implying that in those systems, charge transfer does not require
structural reconfiguration.Comment: submitted to J Chem Phy
Minimal model for beta relaxation in viscous liquids
Contrasts between beta relaxation in equilibrium viscous liquids and glasses
are rationalized in terms of a double-well potential model with
structure-dependent asymmetry, assuming structure is described by a single
order parameter. The model is tested for tripropylene glycol where it accounts
for the hysteresis of the dielectric beta loss peak frequency and magnitude
during cooling and reheating through the glass transition.Comment: Phys. Rev. Lett. (in press
Guidelines for process safety hazard assessment based on process information
In any new chemical process development and design, process safety is a critical aspect to be considered besides economic and technical feasibility of the manufacture of the product. A lack of proper hazard assessment during the design phase may later result in accidents with disastrous consequences to workers, the public as well as the environment. Many methods have been introduced to qualitatively and quantitatively assess the safety level of processes. Despite the availability of a large amount of methods, a systematic framework that details guidelines for hazard identification, risk assessment, safety measure design, and safe critical decision-making is still missing. To address this issue, the main objective of this study was to propose a systematic framework that outlines comprehensive guidelines for assessing the safety performance of processes based on information from the piping and instrumentation diagram (P&ID). Apart from proposing the framework, appropriate strategies for minimizing safety hazards and risks are also recommended. In addition, the user is assisted in selecting the most appropriate assessment method according to his or her needs and the scope and constraints of the assessment. A case study is presented to illustrate the application of the proposed framework
Guidelines for Process Safety Hazard Assessment Based on Process Information
In any new chemical process development and design, process safety is a critical aspect to be considered besides economic and technical feasibility of the manufacture of the product. A lack of proper hazard assessment during the design phase may later result in accidents with disastrous consequences to workers, the public as well as the environment. Many methods have been introduced to qualitatively and quantitatively assess the safety level of processes. Despite the availability of a large amount of methods, a systematic framework that details guidelines for hazard identification, risk assessment, safety measure design, and safe critical decision-making is still missing. To address this issue, the main objective of this study was to propose a systematic framework that outlines comprehensive guidelines for assessing the safety performance of processes based on information from the piping and instrumentation diagram (P&ID). Apart from proposing the framework, appropriate strategies for minimizing safety hazards and risks are also recommended. In addition, the user is assisted in selecting the most appropriate assessment method according to his or her needs and the scope and constraints of the assessment. A case study is presented to illustrate the application of the proposed framework
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Thermal Sweet Taste Machine for Multisensory Internet
This paper presents a new taste interface for multisensory communication called "Thermal Sweet Taste Machine". We developed this interface in order to create sweet sensations, by manipulating the temperature on the tongue, without using chemicals. This device device changes the temperature on the surface of the tongue (from 20°C to 40°C) within a short period of time using a computer controlled circuit. Our preliminary user studies suggested that this device would be effective in two ways; producing the sweet sensations without the aid of chemicals, and enhancing the sweetness of the food and drinks. Here we discuss our concept, development of the interface, and some preliminary studies that has been carried out. We believe our technology would enhance the experiences and capabilities in future multisensory communication in different disciplines such as Human-Computer Interaction, human robot interactions, gaming and interacting with artificial agents
Pro-active QoS resource management schemes for future integrated packet-switched networks
In this research two pro-active dynamic QoS resource management schemes are designed, namely the dynamic QoS control scheme with delay estimation, and the hybrid dynamic QoS control scheme. In both schemes, every new packet arrival is compared against the computed estimated delay it will experience, prior to being admitted into the buffer. If the computed estimated delay expires the requested delay bound, then the packet is dropped. In the hybrid scheme, every packet is first assessed for the estimated delay prior to being admitted into the buffer, subsequently the packets which have been successfully admitted into the buffer are evaluated on the actual delay experienced before being transmitted to the receiver. The paper studies the performance of the two proposed schemes with a dynamic resource management scheme, known as the OCcuPancy_Adjusting (OCP_A). The results obtained through the simulation models show that the proposed schemes have significantly improved the average delay for different traffic patterns. In addition to improving the average delay in delay sensitive traffic, improvement is seen in the average packet loss ratio, and subsequently increasing the throughput of delay sensitive traffic
Anti-inflammatory activity of Nigella sativa oil in rats
Nigella sativa (N. sativa), commonly known as black seed, has been a well known herb since ancient times with
a wide range of healing properties. The aim of this study was to investigate anti-inflammatory activity of N. sativa seed
oil at three dosages on carrageenan-induced paw oedema, total white blood cell (TWBC) count and plasma protein in
rats. Acute inflammation was induced by subplantar injection of carrageenan (0.1 ml, 1 % w/v) into the rat hind paw.
500 mglkg, 1000 mg/kg and 1500 mg/kg of N. sativa oil were administrated orally. Paw oedema, total white blood cell
count and plasma protein were assessed. N. sativa seed oil exerted significant inhibition of paw oedema at the dosage
of 1500 mg/kg at second hour and plasma protein at a dosage of 1000 mg/kg at third hour (p< 0.05). No significant
inhibition ofTWBC count was exerted by N. sativa seed oil at third hour after treatment at dosages used in this study.
There was also dose-dependent correlation of N. sativa seed oil on inhibition of paw oedema. These results support the
traditional use of N. sativa seed oil for the treatment of inflammatory diseases
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