Effects of hydrophilic excipients and compression pressure on physical properties and release behavior of aspirin-tableted microcapsules.

Aspirin ethylcellulose microcapsules were tableted by compression with or without excipients (lactose or polyvinylpyrrolidone [PVP]). The effects of the amount of the excipients and microcapsule size on the crushing strength and release rate of aspirin from tableted microcapsules were investigated. Tablets without excipients had a crushing strength that was independent of the applied pressure and microcapsule size. An increase in compression pressure from 15 to 60 MPa resulted in an increase in the crushing strength of tablets containing 20% or 40% w/w lactose, but the reverse results were obtained for the tableted microcapsules containing 20% or 40% w/w PVP. Results showed that the release rate of aspirin from microcapsules containing lactose or PVP was independent of the compression pressure with the exception of tablets containing 40% w/w lactose. In vitro release profiles of aspirin from tableted microcapsules containing lactose or PVP showed that increasing the concentration of the excipients resulted in an increase in the release rate of aspirin. Values of n were changed by the compression pressure and the added excipients.     

ANALYSIS OF UNSTABLE BEHAVIOR OF PNEUMATIC CONVEYING SYSTEMS

The unstable conveying zone has been recognized by many authors in their attempts to define the minimum conveying velocitv on the dilute phase side of this zone. It was found that the gas flow rate influences the magnitude and frequency of the pressure fluctuations experienced during this type of flow. Generally a reduction of gas flow rate will reduce both the intensity and frequency of the fluctuations.

During the measurement of data for the previous experiments, it was recognized that the pressure fluctuations of dilute and strand flow can serve as simple indicators of the flow stability. An analysis of these fluctuations is presented, which suggests that simple statistical factors can be used to estimate the system condition of operation with respect to the pressure minimum or unstable zone. These elementary trends in the data can be useful for one attempting to optimize a system. This analysis lead to a more intensive approach using Hurst's rescaled range analysis, to examine the changes in pressure fluctuations, which occur when a system undergoes a simulated optimization procedure. The analysis suggested that Hurst's exponent may be used as an indicator of the onset of instability.     

Dental Composites with Magnesium Doped Zinc Oxide Nanoparticles Prevent Secondary Caries in the Alloxan-Induced Diabetic Model

Antibacterial restorative materials against caries-causing bacteria are highly preferred among high-risk patients, such as the elderly, and patients with metabolic diseases such as diabetes. This study aimed to enhance the antibacterial potential of resin composite with Magnesium-doped Zinc oxide (Mg-doped ZnO) nanoparticles (NPs) and to look for their effectiveness in the alloxan-induced diabetic model. Hexagonal Mg-doped ZnO NPs (22.3 nm diameter) were synthesized by co-precipitation method and characterized through ultraviolet-visible (UV-Vis), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) analysis. The Mg-doped ZnO NPs (1, 2.5 and 5% w/w) were then evaluated for antibacterial activity using a closed system in vitro biofilm model. Significant enhancement in the antibacterial properties was observed in composites with 1% Mg-doped ZnO compared to composites with bare ZnO reinforced NPs (Streptococcus mutans, p = 0.0005; Enterococcus faecalis, p = 0.0074, Saliva microcosm, p < 0.0001; Diabetic Saliva microcosm, p < 0.0001). At 1–2.5% Mg-doped ZnO NPs concentration, compressive strength and biocompatibility of composites were not affected. The pH buffering effect was also achieved at these concentrations, hence not allowing optimal conditions for the anaerobic bacteria to grow. Furthermore, composites with Mg-doped ZnO prevented secondary caries formation in the secondary caries model of alloxan-induced diabetes. Therefore, Mg-doped ZnO NPs are highly recommended as an antibacterial agent for resin composites to avoid biofilm and subsequent secondary caries formation in high-risk patients.     

Fair and Reasonable Markup (FaRM) Pricing Model

The Fair and Reasonable Markup (FaRM) is the smallest markup that satisfies the Required Rate of Return (RRR) of the contractor for the particular (or at least the general risk‐class of) project at hand. The model is based on reasonable and easily‐accessible information, and will result in a Minimum Acceptable Price (MAP). The firm cannot accept the project at a price below this MAP without diminishing the “equityholders' wealth.” A modified version of the FaRM Pricing Model for certain contracts under which home‐office overhead expenses must be recovered through FaRM is also presented. Once the FaRM Pricing Model has been implemented, contractors can make more intelligent pricing decisions. Instead of using a subjective markup, which may ignore the cash‐flow differences of various jobs, contractors using FaRM Pricing Model can bid lower on projects which are more attractive and become more competitive while satisfying their RRR. This should result in lower costs to owners. Conversely, by bidding higher on the less‐attractive jobs, contractors will still maintain their RRR should they obtain the contract.     

A new continuous-flow recycle microwave reactor for homogeneous and heterogeneous chemical reactions

A new continuous-flow recycle microwave reactor suitable for organic synthesis has been developed to handle 0.51 quantities of reagents. The apparatus, which is designed for laboratory use, operates at atmospheric pressure in open- or closed-loop mode. It is fitted with a temperature control system. We describe this novel reactor and illustrate its efficiency with examples of organic syntheses carried out using both homogeneous and heterogeneous reactions.     

Adaptive noise reduction using numerically stable fast recursive least squares algorithm

This paper is concerned with adaptive noise reduction based on the fast recursive least squares (FRLS) algorithm. It is well known that the fast recursive least squares (FRLS) algorithm suffers from numerical instability when operating under the effects of finite precision arithmetic. Several numerical solutions of stabilization were proposed in the case of stationary signals. In this work a new version of a numerically stable FRLS algorithm (NS‐FRLS) is proposed. The stability characteristics of this new stabilized algorithm are analysed. The analysis is based on a linear model for the errors in the states of the adaptive filter. Experimental results confirm the merits of adaptive filtering with the NS‐FRLS algorithm over optimum filtering using the solution provided by Wiener–Hopf equations. Copyright © 2006 John Wiley & Sons, Ltd.     

The effect of ammonium sulphate—decabromobiphenyl oxide on the flammability of polyester/cotton blend

A 87.5:12.5 polyester/cotton blended fabric was treated with various concentrations of ammonium sulphate and decabromobiphenyl oxide (DBBO) as well as mixtures of the two additives. The flammability of the resulting systems was determined by the limiting oxygen index (LOI) method and their thermal decomposition by thermogravimetry. Ammonium sulphate was particularly less effective as a flame retardant than the DBBO. Decabromobiphenyl oxide acts in the gas phase to retard the flammability of the polyester while the inorganic salt acts in the condensed phase to decrease that of the cotton. A mechanism for the interaction of ammonium sulphate with cotton was suggested. When a mixture of the two additives containing a high percentage of the bromo-compound was used a significant increase in the LOI values was observed compared to one having the same total loading but containing a higher percentage of ammonium sulphate. This may be attributed to the stabilizing effect of the released ammonia on the intermediate species formed after the liberation of the bromine radicals from the DBBO.     

Assessment of a method for measuring serum thyroxine by radioimmunoassay, with use of polyethylene glycol precipitation

We assessed the efficacy of a new thyroxine radioimmunoassay kit (Abott) in which polyethylene glycol is used to separate bound from free hormone. Mean serum thyroxine was 88 +/- 15 (+/-SD) microgram/liter for 96 normal persons. Results for hypothyroid and hyperthyroid persons were clearly separated from those for normal individuals. Women taking oral contraceptive preparations showed variable increases in their serum thyroxine values. The coefficient of variation ranged from 1 to 3% within assay and from 5.4 to 11% among different assays. Excellent parallelism was demonstrated between thyroxine values estimated by this method and those obtained either by competitive protein binding or by a separate radioimmunoassay for the hormone.     

The preparation of thiophenes. III. From aromatic compounds and carbon disulphide

The high-temperature, vapour-phase reaction of carbon disulphide with 2-isopropyl-phenol and with o-methylbenzyl alcohol in the presence of various catalysts gave high yields of 3-methylbenzo[b]furan and dihydrobenzo[c]thiophene, respectively.     

Liquid distribution and redistribution in packed columns—II. Experimental

The theory of liquid redistribution in packed columns under the influence of a potential when the boundary conditions have been set by differences in permeability between the wall and bulk regions, has been tested in experiment. Liquid distribution in a packed column 0.3 m in diameter and 1.5 m long has been measured for $\text{1}\text{2}$, 1 and 1$\text{1}\text{2}$ in. Raschig rings both with and without gas flow. The trend of experimental points was found to be in general agreement with the theoretical relationship when there was no gas flow. For gas flow conditions in the loading region there was close agreement between experimental and theory.The experimental estimates of the permeability ratio are analysed for the range of experimental conditions.