Management of arsenic-laden water plant sludge by stabilization

When arsenic is co-precipitated with iron hydroxide in an arsenic-removal water plant, a large quantity of sludge is generated which contains a good amount (an average of 6.1 kg As/m³ of sludge) of arsenic. The present paper attempts to find some suitable solutions to disposal of this arsenic-bearing sludge. As a safe means of disposal, stabilization processes such as briquette production, cement mortar and concrete making have been attempted in the present investigation. It has been found that in the preparation of briquette, cement–sand mortar and concrete, mixing up to 10, 18 and 40% of arsenic-bearing sludge by volume, respectively with the other common ingredients did not produce a TCLP leachate beyond its permissible direct inland water discharge standards of 0.2 g/m³ as stipulated by the Ministry of Environment & Forest, Government of India. Also, it was noted that 25% (by volume) of cement could be replaced by fly ash to stabilize arsenic-laden sludge to the tune of 11% by volume of cement–sand (1 : 3) mortar.     

The effect of supplementing red deer (Cervus elaphus) with different forms of ascorbic acid upon the concentration of ascorbic acid in rumen fluid and blood plasma

Two indoor experiments were conducted at the Massey University Deer Research Unit to study whether the blood plasma ascorbic acid (AA) concentration in farmed red deer (Cervus elaphus) could be raised, using a single large intraruminal administration of AA (2.7 g kg^?1 live weight) prior to a simulated slaughter situation. Deer fistulated in the rumen were individually fed chaffed lucerne hay ad libitum at 30 min intervals; feed was then withdrawn 8 h before AA was administered, and fasting continued during the period of rumen fluid and blood sampling (30 h of fasting in total). Blood (jugular vein) and rumen fluid samples were taken 15 min before and at various intervals after dosing with AA. Rumen fluid pH values were also recorded. In Experiment 1 the effects of administration of pure ascorbic acid (AA), ethyl cellulose‐coated ascorbic acid (EC) and silicone‐coated ascorbic acid (SC) were compared. All three types increased rumen fluid and blood plasma AA concentrations to a desirable level (500 µg ml^?1 blood plasma or greater), with the maximum concentrations in both sites occurring 1 h after administration. The area under the concentration versus time curve (AUC), the area under the curve corrected for baseline concentration (AUCB) and the maximum concentration (MAX) of AA in both rumen fluid and blood plasma were not significantly different among the three formulations of AA, indicating that all three were degraded at similar rates in the rumen and that their bioavailabilities were similar. Rumen pH decreased from approximately 7.0 to 5.0 within 1 h of administering each compound, increased to 6.0 after 4 h and then progressively increased to approximately 7.0 after 22 h. Experiment 2 was conducted to investigate the rumen‐buffering effect after dosing with AA with and without added sodium bicarbonate. Including NaHCO₃ increased rumen pH by approximately 1 unit during the first hour after dosing and by 0.7–0.4 units thereafter. AUC and AUCB for rumen fluid were significantly lower for the AA + NaHCO₃ group of deer than for the AA group (p < 0.05), indicating that increasing rumen pH increased the rate of ruminal destruction of AA. AUC, AUCB and MAX of AA in blood plasma were not statistically different between the two treatments (p > 0.05). It was concluded that the single large intraruminal AA dose technique could be used to consistently increase AUC, AUCB and MAX of AA in both rumen fluid and blood plasma. Methods for improving the efficiency of the technique are discussed. © 2002 Society of Chemical Industry     

Evaluating inventory turns for a hospital environment

This paper presents a unique approach, using a modified traditional EOQ model, to manipulate yearly inventory turns and generate optimal space requirements for the Stores operations at Georgetown University Hospital (GUH). The analysis used six months of material dispensed transaction data along with item cost and item size; it generated by item the economic order quantity, order point, safety stock, volume requirement and yearly turns. The advantage of this methodology is that a materiel management system can be configured for acceptable yearly turns such that space requirement can be reduced, avoiding the need for an external warehouse or internal facility construction. The modeling was developed on an IBM 4381 using SAS with transactional data transferred from a Data General (DG) mini computer.     

Kinetics of absorption of sulfur dioxide in dimethylaniline solution

Absorption of sulfur dioxide accompanied by reversible reaction in dimethylaniline has been studied using a short falling-film apparatus. Solutions of the amine in kerosene were used for this purpose. The effects of gas and liquid concentrations, contact time and temperature on the rate of absorption were investigated. Reaction equilibrium constant values were obtained at different temperatures from separate measurement of solubility of sulfur dioxide gas in kerosene as well as in dimethylaniline solutions. The heat of reaction was also calculated from these data. The absorption data could be satisfactorily interpreted by using the penetration theory of mass transfer with simultaneous pseudofirst order chemical reaction. The rate equations for the forward and reverse reactions were established.     

Some effective control chart procedures for reliability monitoring

Control charts are widely used for process monitoring in the manufacturing industry. Little research is available on their use to monitor the failure process of components or systems, which is important for equipment performance monitoring. Some Shewhart control charts, especially those for the number of defects, can be used for monitoring the number of failures per fixed interval; however, they are not effective especially when the failure frequency becomes small. A recent control scheme based on the cumulative quantity between observations of defects has been proposed which can be easily adopted to monitor the failure process for exponentially distributed inter-failure time. An investigation of its use for reliability monitoring is presented in this paper and the scheme can be easily extended to monitor inter-failure times that follow other distributions such as the Weibull distribution. Furthermore, the scheme is extended to the monitoring of time required to observe a fixed number of failures. The advantages of this scheme include the fact that the scheme does not require any subjective sample size, can be used for both high and low reliability items and can detect process improvement even in a high-reliability environment.     

Cure kinetics of epoxy resins by differential scanning calorimetry technique

The curing reactions of epoxy resins with aliphatic amine are investigated using the differential scanning calorimetry technique with a single dynamic scan. The rate of the reaction was followed over the temperature range 30–250°C, and the activation energy and the order of the reaction are determined using four different computational methods. The activation energy for the various epoxy systems is observed in the range 40–76 kJ mol^?1 and the order of the reaction is observed to be ? 1·0.     

High-Temperature deformation of B2 NiAl-base alloys

The high-temperature deformation behavior of three rapidly solidified and processed NiAl-base alloys-NiAl, NiAl containing 2 pct TiB₂, and NiAl containing 4 pct HfC—have been studied and their microstructural and textural changes during deformation characterized. Compression tests were conducted at 1300 and 1447 K at strain rates ranging from 10^-6 to 10^-2 s^-1. HfC-containing material showed dispersion strengthening as well as some degree of grain refinement over NiAl, while TiB^-2 dispersoid-containing material showed grain refinement as well as secondary recrystallization and did not improve high-temperature strength. Hot-pack rolling was also performed to develop thin sheet materials (1.27-mm thick) from these alloys. Without dispersoids, NiAl rolled easily at 1223 K and showed low flow stress and good ductility during-the hot-rolling operation. Rolling of dispersoid-containing alloys was difficult due to strain localization and edge-cracking effects, resulting partly from the high flow stress at the higher strain rate during the rolling operation. Sheet rolling initially produced a (111)< 112) texture, which eventually broke into multiple-texture components with severe deformation. Formerly with Marko Materials, Inc. Formerly Graduate Student, The University of Michigan.     

Effect of epoxidized oils and/or fortifier on glass fibre-epoxy composites

This paper deals with the effect of addition of epoxidized mowrah oil (EMO) and epoxidized cashew-nut-shell liquid (ECNSL) on the properties of glass fibre reinforced conventional epoxy resin, diglycidyl ether of bisphenol-A (DGEBA) composites. The chemical resistance, tensile strength and flexural strength of the laminates increased, while impact and hardness were found to decrease on using these diluents with DGEBA. Dielectric properties such as breakdown strength, dielectric constant (?′) dielectric loss (?″) and loss tangent (tan δ) were compared. A significant improvement in the properties was observed on addition of 20 parts per hundred grams (phr) of an epoxy fortifier, a condensation product of phenyl glycidyl ether and 4-hydroxyacetanilide.     

An alternative approach towards the design of control units

In this communication the individual advantages of both the hardwired and the microprogrammed control units have been exploited to suggest a hybrid approach for the decoding of instructions. The method is simple and straightforward. It retains the fast speed as well as the flexibility aspects. Furthermore, timing analysis has been carried out to justify the effectiveness of the proposed approach.     

Charge-order driven multiferroic and magneto-dielectric properties of rare earth manganates

Charge-order driven magnetic ferroelectricity is shown to occur in several rare earth manganates of the general formula, Ln_1−x A _x MnO₃ (Ln = rare earth, A = alkaline earth). Charge-ordered manganates exhibit dielectric constant anomalies around the charge-ordering or the antiferromagnetic transition temperature. Magnetic fields have a marked effect on the dielectric properties of these compounds, indicating the presence of coupling between the magnetic and electrical order parameters. Magneto-dielectric properties are retained in small particles of the manganates. The observation of magneto-ferroelectricity in these manganates is in accordance with theoretical predictions.