Cost vs. production: disparities in social housing construction in Britain and Germany

The nature of the labour process in the British construction industry is different from that in Germany. The rationale of the British system is based on controlling costs through overseeing contract relations, themselves circumscribing a range of narrow, clearly defined and priced tasks. The production process has become secondary and production expertise restricted. In contrast, in Germany cost aspects are incorporated into, rather than separated from, the production system, built on the interaction of capital and labour and on a high level of production expertise. Employment relations rather than contract relations predominate and circumscribe a set of skills drawn from the potential of the labour force and dependent on broad‐based vocational education. A detailed investigation of social housebuilding projects and the firms involved in Britain and Germany reveals the need for more skills, and a qualitatively different constellation of skills, professional and operative, in Britain.     

Partnering for construction excellence—A reality or myth?

Project partnering has gained popularity in the Hong Kong construction industry since its adoption on the North District Hospital project in 1994. An increasing trend in the use of project partnering in building and construction has been observed over the past decade, with a proven track record of success. In order to critically investigate and examine the effectiveness and performance of project partnering as applied in the local building and construction industry, the Construction Industry Institute, Hong Kong (CII–HK) initiated an industry-driven research study in March 2003 to compare the implementation and outcomes of project partnering practices amongst the public, private and infrastructure sectors as well as between building and infrastructure works. This paper summarizes the key findings derived from the CII–HK funded research study completed in late 2004. Based on the case study of six selected projects, a ‘best practice’ partnering framework is developed. While it has been demonstrated that project partnering can provide extensive benefits to the industry across different sectors, it should be noted that partnering is not a panacea to solve all kinds of problems. What it does is to provide an avenue for people to communicate better thus eliminating unnecessary misunderstanding. It is recommended that partnering be adopted across a wider spectrum of the construction industry during the 21st Century to reap sustainable benefits for construction excellence.     

Disinfection byproduct formation in reverse-osmosis concentrated and lyophilized natural organic matter from a drinking water source

Drinking water treatment and disinfection byproduct (DBP) research can be complicated by natural organic matter (NOM) temporal variability. NOM preservation by lyophilization (freeze-drying) has been long practiced to address this issue; however, its applicability for drinking water research has been limited because the selected NOM sources are atypical of most drinking water sources. The purpose of this research was to demonstrate that reconstituted NOM from a lyophilized reverse-osmosis (RO) concentrate of a typical drinking water source closely represents DBP formation in the original NOM. A preliminary experiment assessed DBP formation kinetics and yields in concentrated NOM, which demonstrated that chlorine decays faster in concentrate, in some cases leading to altered DBP speciation. Potential changes in NOM reactivity caused by lyophilization were evaluated by chlorination of lyophilized and reconstituted NOM, its parent RO concentrate, and the source water. Bromide lost during RO concentration was replaced by adding potassium bromide prior to chlorination. Although total measured DBP formation tended to decrease slightly and unidentified halogenated organic formation tended to increase slightly as a result of RO concentration, the changes associated with lyophilization were minor. In lyophilized NOM reconstituted back to source water TOC levels and then chlorinated, the concentrations of 19 of 21 measured DBPs, constituting 96% of the total identified DBP mass, were statistically indistinguishable from those in the chlorinated source water. Furthermore, the concentrations of 16 of 21 DBPs in lyophilized NOM reconstituted back to the RO concentrate TOC levels, constituting 86% DBP mass, were statistically indistinguishable from those in the RO concentrate. This study suggests that lyophilization can be used to preserve concentrated NOM without substantially altering the precursors to DBP formation.     

Flexible lock-in detection system based on synchronized computer plug-in boards applied in sensitive gas spectroscopy

We present a flexible and compact, digital, lock-in detection system and its use in high-resolution tunable diode laser spectroscopy. The system involves coherent sampling, and is based on the synchronization of two data acquisition cards running on a single standard computer. A software-controlled arbitrary waveform generator is used for laser modulation, and a four-channel analog/digital board records detector signals. Gas spectroscopy is performed in the wavelength modulation regime. The coherently detected signal is averaged a selected number of times before it is stored or analyzed by software-based, lock-in techniques. Multiple harmonics of the modulation signal (1f, 2f, 3f, 4f, etc.) are available in each single data set. The sensitivity is of the order of 10(-5), being limited by interference fringes in the measurement setup. The capabilities of the system are demonstrated by measurements of molecular oxygen in ambient air, as well as dispersed gas in scattering materials, such as plants and human tissue.     

Effects of dietary protein and cholesterol on phosphatidylcholine and phosphatidylethanolamine molecular species in mouse liver

The present study examined the effects of two atherogenic factors, animal protein and cholesterol, on the distribution of fatty acids and the molecular species of major liver phospholipids in mice. Weanling mice were fed a semisynthetic diet supplemented with either casein or soy protein (20%, w/w) in the presence or absence of 0.5% cholesterol for 4 wk. Results from mouse liver showed that animal protein and, more so, dietary cholesterol modified the fatty acid profiles of the phospholipids. Animal protein had no significant effect on the concentration of lipids, but it altered the relative distribution and fatty acid profiles of the phospholipids, phosphatidylcholine and phosphatidylethanolamine. Dietary cholesterol, on the other hand, significantly increased the concentration of liver lipids, but it did not alter the relative distribution of phosphatidylcholine and phosphatidylethanolamine. In cholesterol-fed mice, the proportions of molecular species containing 18∶2n−6 were increased, whereas those containing 20∶4n−6 were decreased, indicating that dietary cholesterol suppressed linoleic acid metabolism. Since cholesterol feeding selectively decreased the ratio of 18∶0/20∶4n−6 in phosphatidylcholine, whereas it increased the 18∶0/18∶2n−6 ratio in phosphatidylethanolamine, this finding suggests that dietary cholesterol may affect the incorporation of fatty acids but not the rate of synthesis of phosphatidylcholine and phosphatidylethanolamine.     

Short-Crack Mechanical Properties and Failure Mechanisms of Si3N4-Matrix/SiC-Fiber Composites

SiC-fiber-reinforced Si₃N₄ composites were fabricated by hot pressing. The indentation-strength technique was applied to study the mechanical properties of these composites. This enabled the investigation of short-crack behavior of continuous-fiber ceramic composites (CFCCs). The flaw tolerance of composite ultimate strength, matrix-cracking stress, and work-of-fracture were investigated. Scanning electron microscopy was used to examine crack–fiber interactions. The ultimate strength was found to be independent of indentation load at a fiber volume fraction f = 0.29, while at f = 0.14 it exhibited a transition from flawsensitive to flaw-independent. The work-of-fracture was found to be independent of indentation load at both fiber volume fractions. The matrix-cracking stress was found to correspond to the first load-drop on the load–displacement curve. It decreased with increasing flaw size and therefore is the steady-state matrix-cracking stress. A failure mechanism transition from catastrophic failure to non-catastrophic failure, coupled with the transition from flawsensitive to flaw-tolerant behavior, was observed by varying the preexisting flaw size and the fiber volume fraction. These transitions were explained by analyzing the relations between ultimate strength, matrix-cracking stress, fiber volume fraction, and preexisting flaw size of the composite materials. Experimental results were compared with predictions from available models.     

Effects of Fiber Volume Fraction on Mechanical Properties of SiC-Fiber/Si3N4-Matrix Composites

The effects of fiber volume fraction on composite mechaniacl properties were examined in SiC-fiber-reinforced Si₃N₄ composites fabricated in our laboratories. Fiber volume fraction was found to have significant effects on important composite properties including failure mode, ultimate strength, matrix-cracking stress, fiber–matrix interfacial shear stress, and work-of-fracture. The composite mechanical properties were improved with increasing fiber volume fraction. However, when the fiber volume fraction was sufficiently large, the composite ultimate strength was degraded. This was related to fiber strength loss as a result of fiber damage from contact with surrounding fibers and abrasive matrix particles during hot pressing.     

A water molecule in the stereospecificity pocket of Candida antarctica lipase B enhances enantioselectivity towards pentan-2-ol

The effect of water activity on enzyme-catalyzed enantioselective transesterification was studied by using a solid/gas reactor. The experimental results were compared with predictions from molecular modelling. The system studied was the esterification of pentan-2-ol with methylpropanoate as acyl donor and lipase B from Candida antarctica as catalyst. The data showed a pronounced water-activity effect on both reaction rate and enantioselectivity. The enantioselectivity increased from 100, at water activity close to zero, to a maximum of 320, at a water activity of 0.2. Molecular modelling revealed how a water molecule could bind in the active site and obstruct the binding of the slowly reacting enantiomer. Measurements of enantioselectivity at different water-activity values and temperatures showed that the water molecule had a high affinity for the stereospecificity pocket of the active site with a binding energy of 9 kJ mol-1, and that it lost all its degrees of rotation, corresponding to an entropic energy of 37 J mol-1 K-1.     

Application of the induction plasma to the synthesis of two dimensional steam methane reforming Ni/Al2O3 catalyst

The purpose of the study is to develop a new protocol for preparing supported two dimensional catalysts with high external and low internal surface by combining thermal plasma spraying and thermal plasma chemical vapour deposition (TPCVD) processes. The method was tested for the production of an Al₂O₃ supported Ni catalysts used for methane steam reforming. The deposition of catalytic materials is made in 2 successive steps. The first step deals with alumina powder sprayed by induction plasma spraying (IPS) on a molybdenum substrate. The experimental conditions have been turned towards γ-Al₂O_3. The second stage deals with the deposition of nickel at the nanometric scale on the alumina layer using the thermal plasma chemical vapour deposition method. This last step was focused on the study of the influence of the nozzle type employed for the nickel solution spraying, the reactor internal pressure, the concentration and the flow rate of nickel salts solution, Ni(NO₃)₂·6H₂O, on the catalyst response. The formulations were tested as methane steam reforming catalysts.The results demonstrate that the catalyst morphology depends on plasma projection conditions and show the effectiveness of combining IPS and TPCVD processes for producing catalysts in methane steam reforming.