The manufacturing of packaged capillary action microfluidic systems by means of CO2 laser processing

In this article we demonstrate a simple yet robust rapid prototyping manufacturing technique for the construction of autonomous microfluidic capillary systems by means of CO₂ laser processing. The final packaging of the microfluidic device is demonstrated using thermal lamination bonding and allows for a turnaround time of approximately 30 min to 3 h from activation of the laser system to device use. The low-cost CO₂ laser system is capable of producing repeatable microfluidic structures with minimum feature sizes superior than 100–150 μm over channel depths of more than 100 μm. This system is utilised to create capillary pump and valve designs within poly (methyl methacrylate) (PMMA) substrates. Such components are part of advanced systems that can self initiate and maintain the flow of various volumes of fluids from an input to a collection reservoir, whilst also controlling the progression of the flow through the various demonstrated valve type structures. The resulting systems could prove a very useful alternative to traditional, non-integrated, fluidic actuation and flow control systems found on-chip, which generally require some form of energy input, have limited portable capabilities and require more complex fabrication procedures.     

A model for predicting heat transfer through noninsulated unloaded steel-stud gypsum board wall assemblies exposed to fire

With the advent of performance-based codes and performance-based fire safety design options, validated fire-resistance models have become essential. In this paper, a one-dimensional heat transfer model for steel-stud, noninsulated, unloaded gypsum board protected wall assemblies is presented. Also presented are a comparison between temperature predictions and measured temperatures at different locations in gypsum board wall assemblies as well as a comparison between the predicted and measured fire-resistance ratings. The model, which predicts slightly conservative fire-resistance ratings compared to the experimental measurements, is appropriate for most fire safety engineering applications. Considerations for further model development are identified.     

Packaging handling evaluation methods in the grocery retail industry

The grocery retail industry, with its large product volumes, low margins and fierce competition, is constantly seeking efficiency improvements in its supply chain. The grocery retail industry uses an immense amount of packaging and is directly affected by packaging logistics activities. There is, therefore, a potential for efficiency improvements in the grocery retail supply chain through the integration and development of new systems of packaging and logistics. Packaging handling is identified as one of the main activities that has a strong impact on the overall logistical cost of a grocery chain. This research article investigates packaging handling evaluation methods and discusses how these are employed to benefit the industry. Case studies, involving six major companies from the Swedish grocery retail industry, have been used to evaluate packaging and logistics activities. This work, together with a literature review, was used to identify the need for evaluative methods and the present availability of such methods. The results indicated a lack of sufficient and usable packaging handling evaluation methods in today's grocery and packaging industry especially from a logistical point of view. The paper also highlights the lack of systematization among the few methods used and discusses how these can be used to build a systematic and multifunctional evaluation model in order to utilize the information from different studies to build a knowledge base for the future. Copyright © 2001 John Wiley & Sons, Ltd.     

An efficient method for combining adaptive echo and noise canceller in hands‐free systems

Acoustic interferences severely degrade the quality and the intelligibility of the desired speech signal, thus posing a severe problem for many speech applications. Several acoustic echo cancellation (AEC) techniques have been proposed with a view to solving this problem. There are, however, few reports of AEC methods working under real noisy conditions. In this paper, we investigate the maximum positive synergies of the combination of acoustic echo canceller with a new adaptive beamformer. The proposed system achieves both the AEC and noise reduction of speech in an actual environment with real noise sources. Since the AEC is located behind the fixed beamformer of the new adaptive beamformer only one AEC is required for an arbitrary number of array elements, and the AEC does not feel any repercussions from the new adaptive beamformer. The proposed system was implemented in a real environment using National Instruments NI‐PXI‐1042Q controller system and data acquisition card PXI‐4472. Experimental results show that the proposed system has successfully improved the performance of hands‐free systems. Copyright © 2008 John Wiley & Sons, Ltd.     

GC and GC/MS Analysis of Essential Oil Composition of the Endemic Soqotraen Leucas virgata Balf.f. and Its Antimicrobial and Antioxidant Activities

Leucas virgata Balf.f. (Lamiaceae) was collected from the Island Soqotra (Yemen) and its essential oil was obtained by hydrodistillation. The chemical composition of the oil was investigated by GC and GC-MS. Moreover, the essential oil was evaluated for its antimicrobial activity against two Gram-positive bacteria, two Gram-negative bacteria, and one yeast species by using broth micro-dilution assay for minimum inhibitory concentrations (MIC) and antioxidant activity by measuring the scavenging activity of the DPPH radical. The investigation led to the identification of 43 constituents, representing 93.9% of the total oil. The essential oil of L. virgata was characterized by a high content of oxygenated monoterpenes (50.8%). Camphor (20.5%) exo-fenchol (3.4%), fenchon (5.4%), and borneol (3.1%) were identified as the main components. Oxygenated sesquiterpenes were found as the second major group of compounds (21.0%). β-Eudesmol (6.1%) and caryophyllene oxide (5.1%) were the major compounds among oxygenated sesquiterpenes. The results of the antimicrobial assay showed that the oil exhibited a great antibacterial activity against the tested S. aureus, B. subtilis, and E. coli. No activity was found against P. aeruginosa and C. albicans. Moreover, the DPPH-radical scavenging assay exhibited only a moderate antioxidant activity (31%) for the oil at the highest concentration tested (1 mg/mL).     

Staphylococcus aureus nasal carriage in a Moroccan dialysis center and isolates characterization

Staphylococcus aureus, which has its ecological niche in the anterior nares, has been shown to cause a variety of infectious diseases mainly for patients in hemodialysis units. We performed this study to evaluate the prevalence of nasal S. aureus carriage among hemodialysis outpatients, to determine the antimicrobial susceptibility of isolates, to characterize the virulence genes, and to identify associated risk factors. Nares swab specimens were obtained from 70 outpatients on hemodialysis between March and June 2010. Samples were plated immediately onto S. aureus specific media and pattern of antibacterial sensitivity was determined using disk diffusion method. Polymerase chain reaction was used to detect nuc, mecA, and genes encoding staphylococcal toxins. Medical record of patients was explored to determine S.aureus carriage risk factors. Nasal screening identified 42.9% S. aureus carriers with only one (3.3%) methicillin‐resistant S. aureus isolate. Among the methicillin‐susceptible S. aureus isolates, high rate of penicillin resistance (81.8%) has been detected. The identified risk factors were male gender and age ≤ 30 years. Research of virulence factors showed a high genetic diversity among the 30 S. aureus isolates. Twenty‐one (70%) of them had at least one virulence gene, of which 3.3% were Panton‐Valentine leukocidin (lukS/F‐PV) genes. S. aureus carriage must be screened for at regular intervals in hemodialysis patients. Setting up a bacterial surveillance system is one of the strategies to understand the epidemiology of methicillin‐resistant S. aureus, to guide local antibiotic policy and prevent spread of antibiotic‐resistant S. aureus.     

Frying of potato chips in a blend of canola oil and palm olein: changes in levels of individual fatty acids and tocols

The changes occurring in the levels of nutritionally relevant oil components were assessed during repeated frying of potato chips in a blend of palm olein and canola oil (1:1 w/w). The blend suffered minimal reductions in omega‐3 and omega‐6 polyunsaturated fatty acids. There was no significant difference between the fatty acid composition of the oil extracted from the product and that of the frying medium, in all three cases. The blend also contained a significant amount of tocols which add a nutritional value to the oil. The concentration of the tocols was satisfactorily retained over the period of oil usage, in contrast to the significant loses observed in the case of the individual oils. The blend also performed well when assessed by changes in total polar compounds, free fatty acids, p‐anisidine value. When fried in used oil, the product oil content increased progressively with oil usage time. This study shows that blended frying oils can combine good stability and nutritional quality.     

Combustion synthesis of single-phase β-sialons (z = 2–4)

Single-phase β-sialon powders (z = 2–4) have been prepared with homogeneous compositions by the combustion synthesis. The raw materials (Si, Al and SiO₂) were combusted under N₂ pressure of 1 MPa. Without using a diluent, the reaction temperatures were very high (>2000 °C) and the combustion products contained Si and Al residues. With addition of commercial β-sialon (z = 1) as a diluent (up to 50 wt%), both the reaction temperatures and amount of residual Si and Al significantly decreased. The combustion reactions completed at 50 wt% dilution, and pure β-sialon phases were synthesized. When the combustion product itself is used instead of the commercial diluent, the phase content of desired z value increased with the repetition times until a single-phase powder is produced. The sinterability of the synthesized powders was then tested using 5 wt% Y₂O₃ as a sintering aid by the spark plasma sintering (SPS).     

Coal-ash deposit corrosion of some steels and nimonic alloys

The corrosion behaviour of some commercial austenitic steels and nimonic aalloys has been studied at 650, 800, 900 and 1000°C in air and in the presence of ash residues obtained from coals of Indian origin. The ash is non-aggressive at temperature s where formation of corrosion-producing alkali iron trisulphates is normally expected; on the contrary, the silicates present in the ash provide protection against corrosron. A.t higher temperatures the ash is corrosive due to onset of sulphidation and molten alhali sulphate attack. In general, the corrosion rates of high-ash coated alloys are much higher than those coated with low ash. The higher corrosion rates in the former have been attributed to a higher level of free silica in the ash which undergoes slag-type reactions. Both types of ash exhibit two different and distinct scale morphologies.