The influence of type of sexual partnership on male condom use: empirical evidence from the South African construction industry

There are indications that gender has an effect on individual risk factors and pathways to HIV diagnoses and treatment. Furthermore, there is growing recognition that to improve HIV-related health outcomes for men, it is important to understand their experiences and perspectives. Perhaps because of the physical nature of construction work, the South African construction industry is dominated by men. Given that employed men are a hard-to-reach community population group, the construction workplace offers an ideal environment for data collection and delivery of non-health-facility-based HIV prevention and treatment interventions. Furthermore, workers in the construction industry have been identified as being at a heightened risk of acquiring HIV and AIDS because of work-related travel, the ubiquity of transactional sex around worker hostels and having an increased likelihood of multiple and concurrent sex partnerships. As a consequence, this study examines the association between condom use and sexual partnerships among men working in the construction industry. A purposive cross-sectional survey was used to collect data from 450 workers across 18 construction sites in the Western Cape province of South Africa. The types of sexual partnership had three categories: regular sex partnerships, casual sex partnerships and sex worker partnerships. Frequency of condom use was determined to be highest with casual sex partners (51.2%), followed by sex workers (40.6%) and regular sex partners (25.6%). Hierarchical multiple linear regression analysis was used to examine the demographic, experiential, behavioural and cognitive predictors of condom use across the three categories of sexual partnership. The results indicate that an individual's perception of control over condom use, and the perceived threat posed by HIV and AIDS are significantly associated with consistent condom use, even after accounting for differences in partner type. Implications of the findings are discussed, and directions for future research on the association between sexual partnerships and condom use are offered.

Influence of the sintering atmosphere on the physico-chemical properties and the osteoclastic resorption of β-tricalcium phosphate cylinders

One of the most widely used materials for bone graft substitution is β-Tricalcium phosphate (β-TCP; β-Ca3(PO4)2). β-TCP is typically produced by sintering in air or vacuum. During this process, evaporation of phosphorus (P) species occurs, leading to the formation of a calcium-rich alkaline layer. It was recently shown that the evaporation of P species could be prevented by co-sintering β-TCP with dicalcium phosphate (DCPA; CaHPO4; mineral name: monetite). The aim of this study was to see how a change of sintering atmosphere could affect the physico-chemical and biological properties of β-TCP. For this purpose, three experimental groups were considered: β-TCP cylinders sintered in air and subsequently polished to remove the surface layer (control group); the same polished cylinders after subsequent annealing at 500 °C in air to generate a calcium-rich alkaline layer (annealed group); and finally, β-TCP cylinders sintered in a monetite-rich atmosphere and subsequently polished (monetite group). XPS analysis confirmed that cylinders from the annealed group had a significantly higher Ca/P molar ratio at their surface than that of the control group while this ratio was significantly lower for the cylinders from the monetite group. Sintering β-TCP in the monetite-rich atmosphere significantly reduced the grain size and increased the density. Changes of surface composition affected the activity of osteoclasts seeded onto the surfaces, since annealed β-TCP cylinders were significantly less resorbed than β-TCP cylinders sintered in the monetite-rich atmosphere. This suggests that an increase of the surface Ca/P molar ratio leads to a decrease of osteoclastic resorption. STATEMENT OF SIGNIFICANCE: Minimal changes of surface and bulk (< 1%) composition have major effects on the ability of osteoclasts to resorb β-tricalcium phosphate (β-TCP), one of the most widely used ceramics for bone substitution. The results presented in this study are thus important for the calcium phosphate community because (i) β-TCP may have up to 5% impurities according to ISO and ASTM standards and still be considered to be "pure β-TCP", (ii) β-TCP surface properties are generally not considered during biocompatibility assessment and (iii) a rationale can be proposed to explain the various inconsistencies reported in the literature on the biological properties of β-TCP.

Atomic-Level and Surface Structure of Calcium Silicate Hydrate Nanofoils

Deciphering the calcium silicate hydrate (C-S-H) surface is crucial for unraveling the mechanisms of cement hydration and property development. Experimental observations of C-S-H in cement systems suggest a surface termination which is fundamentally different from the silicate-terminated surface assumed in many atomistic level studies. Here, a new multiparameter approach to describing the (001) basal C-S-H surface is developed, which considers how the surface termination affects the overall properties (Ca/Si ratio, mean chain length, relative concentration of silanol and hydroxide groups). Contrary to current beliefs, it is concluded that the (001) C-S-H surface is dominantly calcium terminated. Finally, an adsorption mechanism for calcium and hydroxide ions is proposed, which is in agreement with the surface charge densities observed in previous studies.

Atomic-Level Structure of Zinc-Modified Cementitious Calcium Silicate Hydrate

It has recently been demonstrated that the addition of zinc can enhance the mechanical strength of tricalcium silicates (C₃S) upon hydration, but the structure of the main hydration product of cement, calcium silicate hydrate (C-S-H), in zinc-modified formulations remains unresolved. Here, we combine ²⁹Si DNP-enhanced solid-state nuclear magnetic resonance (NMR), density functional theory (DFT)-based chemical shift computations, and molecular dynamics (MD) modeling to determine the atomic-level structure of zinc-modified C-S-H. The structure contains two main new silicon species (Q^(1,Zn) and Q^(2p,Zn)) where zinc substitutes Q⁽¹⁾ silicon species in dimers and bridging Q^(2b) silicon sites, respectively. Structures determined as a function of zinc content show that zinc promotes an increase in the dreierketten mean chain lengths.

Psychometric properties of the Drug Use Disorders Identification Test (DUDIT) and prevalence of drug use among SA site-based construction workers

Construction workers in South Africa are an at-risk group for HIV/AIDS. Substance misuse, other than alcohol, is associated with poor decision-making, risky lifestyle behaviour, and non-use of condoms. Substance misuse is also associated with harmful and hazardous alcohol consumption and depression. The Drug Use Disorders Identification Test (DUDIT) is a widely used screening tool to detect drug abuse. The present study examines both the psychometric properties of the DUDIT and the prevalence of drug abuse among construction workers. A field study involving 496 male workers at 18 construction sites of seven construction companies in the Western Cape province of South Africa, was undertaken. Descriptive statistics, reliability, and exploratory and confirmatory factor analyses were used to determine the prevalence of substance use, and the dimensionality, reliability and construct validity of the DUDIT. Approximately 10% of participants reported some form of substance use. Four hundred and sixty-seven employees (94.2%) were determined not to have drug-related problems (DUDIT score < 6). Of the at-risk employees (score >5), 5.0% (n = 25) were classified as 'possibly having a drug-related problem' (score 6-24) and 0.8% (n = 4) as 'possibly highly dependent on drugs' (score 25 or more). Of the 47 employees who reported drug use, 29 (61.7%) were classified as having a medium to high risk in relation to drug use. The internal consistency of the DUDIT was very good. The DUDIT reported a one-factor factorial structure, and the model fit indices indicated good model fit to the data. All factor loadings were significant, but there was some evidence of collinearity. Concurrent validity was demonstrated. DUDIT items 1 and 10 require further investigation due to their poor performance compared to the other items. The contribution of these two items needs to be investigated using item response theory (IRT).

Effect of minor amounts of β-calcium pyrophosphate and hydroxyapatite on the physico-chemical properties and osteoclastic resorption of β-tricalcium phosphate cylinders

β-Tricalcium Phosphate (β-TCP), one of the most used bone graft substitutes, may contain up to 5 wt% foreign phase according to standards. Typical foreign phases include β-calcium pyrophosphate (β-CPP) and hydroxyapatite (HA). Currently, the effect of small amounts of impurities on β-TCP resorption is unknown. This is surprising since pyrophosphate is a very potent osteoclast inhibitor. The main aim of this study was to assess the effect of small β-CPP fractions (<1 wt%) on the in vitro osteoclastic resorption of β-TCP. A minor aim was to examine the effect of β-CPP and HA impurities on the physico-chemical properties of β-TCP powders and sintered cylinders. Twenty-six batches of β-TCP powder were produced with a Ca/P molar ratio varying between 1.440 and 1.550. Fifteen were further processed to obtain dense and polished β-TCP cylinders. Finally, six of them, with a Ca/P molar ratio varying between 1.496 (1 wt% β-CPP) and 1.502 (1 wt% HA), were incubated in the presence of osteoclasts. Resorption was quantified by white-light interferometry. Osteoclastic resorption was significantly inhibited by β-CPP fraction in a linear manner. The presence of 1% β-CPP reduced β-TCP resorption by 40%, which underlines the importance of controlling β-CPP content when assessing β-TCP biological performance.

Determinants of HIV testing behaviour among male South African construction workers

The global trend of poorer outcomes across the HIV treatment cascade for men has drawn attention to the importance of engaging men in prevention and treatment services. The South African construction industry is one of the economic sectors most adversely affected by HIV/AIDS. Previous research on HIV testing behaviour among workers in the industry has revealed that male workers are less likely to be tested than female workers. Given this gender differential, this study employed a field-administered survey to gather data from 450 site-based, male construction workers in Western Cape, South Africa. An integrated model comprising demographic, cognitive, and behavioural factors was then hypothesised to explain HIV testing behaviour. Bivariate analysis and structural equation modelling were then used to test the model. Findings indicate that HIV knowledge, having previously had an STI, and possessing a positive attitude towards HIV testing are terminal predictors of testing behaviour. As a strategy for positively influencing testing behaviour, employers should ensure that effective communication about HIV testing is established with workers across all levels of education and ethnic groups. Interventions relating to risky sexual behaviour need particular attention, and where possible HIV testing should be coupled with general STI screening.

The dark side of teamwork–the relationship between social stressors, social resources and team member well-being in monocultural and multicultural work teams

Purpose

The purpose of this paper is to explore the relationship between cultural diversity in teams and team members' individual well-being. The paper further explores the relationship between social resources, social stressors, team member well-being and the influence of the type of team individuals are working in (mono- vs. multicultural), gender and individualism/collectivism (IC).

Design/methodology/approach

Using data collected via an online survey, the authors analyzed 659 responses from individuals working in mono- and multicultural work teams. A theoretical model explaining the influence of social stressors, social resources, and social and demographic variables was proposed and tested using structural equation modeling.

Findings

The results indicate that members of multicultural work teams perceive significantly more social stressors and lower levels of social resources than do members of monocultural teams. Higher levels of social stressors suggest decreased psychological well-being, while social resources have an indirect positive effect on psychological well-being. Furthermore, personal characteristics, namely, individualism and gender, have direct effects on the perception of social stressors and indirect effects on team member well-being.

Originality/value

This paper demonstrates that cultural diversity in teams can influence the social stressors and resources that individual team members experience. Moreover, the pivotal role of social resources in the facilitation of team member well-being is highlighted primarily through its direct effect on social stressors and its concomitant indirect effect on well-being.

The Atomic-Level Structure of Cementitious Calcium Aluminate Silicate Hydrate

Despite use of blended cements containing significant amounts of aluminum for over 30 years, the structural nature of aluminum in the main hydration product, calcium aluminate silicate hydrate (C-A-S-H), remains elusive. Using first-principles calculations, we predict that aluminum is incorporated into the bridging sites of the linear silicate chains and that at high Ca:Si and H₂O ratios, the stable coordination number of aluminum is six. Specifically, we predict that silicate-bridging [AlO₂(OH)₄]^5- complexes are favored, stabilized by hydroxyl ligands and charge balancing calcium ions in the interlayer space. This structure is then confirmed experimentally by one- and two-dimensional dynamic nuclear polarization enhanced ²⁷Al and ²⁹Si solid-state NMR experiments. We notably assign a narrow ²⁷Al NMR signal at 5 ppm to the silicate-bridging [AlO₂(OH)₄]^5- sites and show that this signal correlates to ²⁹Si NMR signals from silicates in C-A-S-H, conflicting with its conventional assignment to a "third aluminate hydrate" (TAH) phase. We therefore conclude that TAH does not exist. This resolves a long-standing dilemma about the location and nature of the six-fold-coordinated aluminum observed by ²⁷Al NMR in C-A-S-H samples.

Cathodoluminescent screen imaging system for seeded blob detection in toroidal plasma experiment

We designed and built a diagnostic based on a cathodoluminescent screen for the detection of turbulent plasma structures with high spatial resolution. The screen is coated with a low threshold energy cathodoluminescent powder that emits light when exposed to a plasma. The emitted light is imaged with a fast frame camera combined with an image intensifier and an optical bandpass filter. The diagnostic is used to study turbulent structures and seeded blobs. The results are analyzed with pattern recognition algorithms to track the turbulent structures and study their evolution in time.

Investigation on Fatigue Threshold Testing Methods in a Near Lamellar TiAl Alloy

The effects of influential fatigue testing factors, including loading schemes (e.g., traditional load shedding and staircase load increasing), morphology of crack starters, and precracking approaches on the near-threshold fatigue crack growth behaviors for a near lamellar γ-TiAl alloy (Ti-45Al-2Mn-2Nb-1B) were investigated at room temperature and 650 °C. The results showed that the measured fatigue threshold values in lamellar γ-TiAl alloys are very sensitive to the applied testing procedures. For example, the staircase load-increasing method yielded smaller threshold values. When such a load-increasing method was used, the threshold values were measured either from a notch machined by electro-discharge machining or prepared by a compression-compression fatigue loading. Moreover, some differences could be seen with respect to the morphologies of the crack starters. Most of the above influences are associated with the brittle nature of the material and the characteristics of the lamellar microstructures, and closure effects are primarily induced by crack wake roughness or unbroken ligaments.

Kinetics and Mechanism of Metal Nanoparticle Growth via Optical Extinction Spectroscopy and Computational Modeling: The Curious Case of Colloidal Gold

An overarching computational framework unifying several optical theories to describe the temporal evolution of gold nanoparticles (GNPs) during a seeded growth process is presented. To achieve this, we used the inexpensive and widely available optical extinction spectroscopy, to obtain quantitative kinetic data. In situ spectra collected over a wide set of experimental conditions were regressed using the physical model, calculating light extinction by ensembles of GNPs during the growth process. This model provides temporal information on the size, shape, and concentration of the particles and any electromagnetic interactions between them. Consequently, we were able to describe the mechanism of GNP growth and divide the process into distinct genesis periods. We provide explanations for several longstanding mysteries, for example, the phenomena responsible for the purple-greyish hue during the early stages of GNP growth, the complex interactions between nucleation, growth, and aggregation events, and a clear distinction between agglomeration and electromagnetic interactions. The presented theoretical formalism has been developed in a generic fashion so that it can readily be adapted to other nanoparticulate formation scenarios such as the genesis of various metal nanoparticles.

Rapid evaluation of bioactive Ti-based surfaces using an in vitro titration method

The prediction of implant behavior in vivo by the use of easy-to-perform in vitro methods is of great interest in biomaterials research. Simulated body fluids (SBFs) have been proposed and widely used to evaluate the bone-bonding ability of implant materials. In view of its limitations, we report here a rapid in vitro method based on calcium titration for the evaluation of in vivo bioactivity. Using four different titanium surfaces, this method identifies that alkaline treatment is the key process to confer bioactivity to titanium whereas no significant effect from heat treatment is observed. The presence of bioactive titanium surfaces in the solution during calcium titration induces an earlier nucleation of crystalline calcium phosphates and changes the crystallization pathway. The conclusions from this method are also supported by the standard SBF test (ISO 23317), in vitro cell culture tests using osteoblasts and in vivo animal experiments employing a pelvic sheep model.

Synergistic Effect of Fluorinated and N Doped TiO₂ Nanoparticles Leading to Different Microstructure and Enhanced Photocatalytic Bacterial Inactivation

This work focuses on the development of a facile and scalable wet milling method followed by heat treatment to prepare fluorinated and/or N-doped TiO₂ nanopowders with improved photocatalytic properties under visible light. The structural and electronic properties of doped particles were investigated by various techniques. The successful doping of TiO₂ was confirmed by X-ray photoelectron spectroscopy (XPS), and the atoms appeared to be mainly located in interstitial positions for N whereas the fluorination is located at the TiO₂ surface. The formation of intragap states was found to be responsible for the band gap narrowing leading to the faster bacterial inactivation dynamics observed for the fluorinated and N doped TiO₂ particles compared to N-doped TiO₂. This was attributed to a synergistic effect. The results presented in this study confirmed the suitability of the preparation approach for the large-scale production of cost-efficient doped TiO₂ for effective bacterial inactivation.

Interaction of biologically relevant ions and organic molecules with titanium oxide (rutile) surfaces: A review on molecular dynamics studies

The surface of a biomaterial can play a major role in its biological fate since the surface is the primary pathway for its interaction with the body. As the natural response of the body to a foreign material is to encapsulate it with a fibrous material, the interactions between the body and the biomaterial are mediated by this fibrous layer. Initial interactions occur between the biomaterial surface, water, ionic species and organic molecules, which then mediate further interactions with body tissues. Surface engineering can influence these interactions and hence, improve the biocompatibility of the biomaterial. Therefore, both experimental and computational studies have been interested in phenomena happening at the solid-solution interface as their mechanisms and driving forces can point to new directions for biomaterial design and evaluation. In this review, we summarize the computational work on the interaction of titanium oxide surfaces (mainly rutile) with solvated ions and organic molecules by means of molecular dynamics, with a certain relevance to bioactivity testing protocols. The primary goal of this review is to present the current state of the art and draw attention to points where further investigations are required.

HIV infection in the South African construction industry

South Africa has one of the highest HIV prevalences in the world, and compared with other sectors of the national economy, the construction industry is disproportionately adversely affected. Using data collected nationally from more than 57,000 construction workers, HIV infection among South African construction workers was estimated, together with an assessment of the association between worker HIV serostatus and worker characteristics of gender, age, nature of employment, occupation, and HIV testing history. The HIV infection of construction workers was estimated to be lower than that found in a smaller 2008 sample. All worker characteristics are significantly associated with HIV serostatus. In terms of most at-risk categories: females are more at risk of HIV infection than males; workers in the 30-49 year old age group are more at risk than other age groups; workers employed on a less permanent basis are more at risk; as are workers not having recently tested for HIV. Among occupations in the construction industry, general workers, artisans, and operator/drivers are those most at risk. Besides yielding more up-to-date estimated infection statistics, this research also identifies vulnerable sub-groups as valuable pointers for more targeted workplace interventions by construction firms.

A comparative study of simulated body fluids in the presence of proteins

Simulated body fluid (SBF) is widely used as part of an in vitro method to evaluate implant materials such as their apatite forming ability (AFA), a typical indication of potential bone-bonding ability in vivo. We report the use of carbonate-buffered SBFs as potential solutions for implant evaluation and the effect of proteins, represented by bovine serum albumin (BSA) in SBFs on the formation of hydroxyapatite (HA). These solutions are buffered by the thermodynamic equilibrium with 5% CO₂ in an incubator, and result in a deposition of carbonated HA. Using several titanium-based surfaces, these solutions were studied in comparison with the widely-used SBF (ISO 23317). The presence of BSA strongly inhibited the formation of HA in traditional SBF, while HA can still be observed in carbonate-buffered SBFs. A kinetic study reveals that the inhibitory effect is concentration dependent with 0.1g/L and 1g/L of BSA having little effect on HA growth but a complete inhibition of HA formation at 5g/L of BSA, as tested using NaOH treated titanium with a known positive AFA. The decrease in solution pH and free calcium concentrations in SBFs due to the addition of BSA is not significant, suggesting other causes for the strong inhibitory effect.

STATEMENT OF SIGNIFICANCE

The successful use of simulated body fluids (SBFs) to evaluate potential bioactive implants relies on the better understanding of the heterogeneous nucleation and growth of hydroxyapatite in solution. Although a standardized recipe for SBF was developed over a decade ago, a few key issues remain to be understood, i.e. the behavior of carbonate-buffered SBFs having similar buffering mechanism as human blood, and the effect of proteins on hydroxyapatite formation on bioactive materials. This paper addresses these two issues and would help the reader better understand the subtleties in this domain and better interpret the results generated using SBFs.

AIDS-related knowledge, stigma and customary beliefs of South African construction workers

Customary beliefs about the cause/s of AIDS are significantly related to whether or not individuals will undergo HIV testing. This study examined the cultural beliefs of construction workers in terms of their demographic and lifestyle behavioural characteristics, and their AIDS-related knowledge and stigma attitudes, to help inform improved work-based AIDS-education interventions by construction firms. A total of 512 workers drawn from 6 firms operating on 18 construction sites in the Western Cape province participated in the study. Thirty-seven per cent of participants either endorsed customary beliefs/explanations about the cause of AIDS, or were unsure. AIDS-related knowledge proved a significant differentiator of participants endorsing customary beliefs (aOR = 0.8, 95% CI, 0.6-1.0), or being unsure (aOR = 0.5, 95% CI, 0.4-0.6), compared to participants not endorsing such beliefs. Stigma (aOR = 1.3, 95% CI, 1.1-1.7) proved a significant differentiator of participants with more polarized beliefs, namely, those endorsing customary beliefs compared to those not endorsing such beliefs, but was not significant in differentiating these categories from that of being unsure. The challenges to testing behaviour from incorrect AIDS knowledge may be amplified by adherence to customary beliefs that discount scientific explanations about the cause of AIDS. Interventions are required to specifically address misinformation or incorrect knowledge about AIDS derived from traditional beliefs, and should explicitly target persons who either endorse such beliefs or are somewhat equivocal about them. The role of peer educators is highlighted. Traditional healers, given their credibility and status within many traditional cultures, may also have an important role to play in this regard.

Validating survey measurement scales for AIDS-related knowledge and stigma among construction workers in South Africa

BACKGROUND

Construction workers in South Africa are regarded as a high-risk group in the context of HIV/AIDS. HIV testing is pivotal to controlling HIV transmission and providing palliative care and AIDS-related knowledge and stigma are key issues in addressing the likelihood of testing behaviour. In exploring these issues, various studies have employed an 11-item AIDS-related knowledge scale (Kalichman and Simbayi, AIDS Care 16:572-580, 2004) and a 9-item stigma scale (Kalichman et al., AIDS Behav 9:135-143, 2005), but little evidence exists confirming the psychometric properties of these scales.

METHODS

Using survey data from 512 construction workers in the Western Cape, South Africa, this research examines the validity and reliability of the two scales through exploratory and confirmatory factor analysis and internal consistency tests.

RESULTS

From confirmatory factor analysis, a revised 10-item knowledge scale was developed (χ2 /df ratio = 1.675, CFI = 0.982, RMSEA = 0.038, and Hoelter (95 %) = 393). A revised 8-item stigma scale was also developed (χ2 /df ratio = 1.929, CFI = 0.974, RMSEA = 0.045, and Hoelter (95 %) = 380). Both revised scales demonstrated good model fit and all factor loadings were significant (p < 0.01). Reliability analysis demonstrated excellent to good internal consistency, with alpha values of 0.80 and 0.74, respectively. Both revised scales also demonstrated satisfactory convergent and divergent validity. Limitations of the original survey from which the data was obtained include the failure to properly account for respondent selection of language for completion of the survey, use of ethnicity as a proxy for identifying the native language of participants, the limited geographical area from which the survey data was collected, and the limitations associated with the convenience sample. A limitation of the validation study was the lack of available data for a more robust examination of reliability beyond internal consistency, such as test-retest reliability.

CONCLUSIONS

The revised knowledge and stigma scales offered here hold considerable promise as measures of AIDS-related knowledge and stigma among South African construction workers.

Pro-oxidant effects of nano-TiO2on Chlamydomonas reinhardtii during short-term exposure

This is the first continuous quantification of abiotic and biotic nano-TiO₂– stimulated H₂O₂revealing that measured extracellular and intracellular pro-oxidant endpoints inC. reinhardtiican differ significantly.

Surface 3D Micro Free Forms: Multifunctional Microstructured Mesoporous α-Alumina by in Situ Slip Casting Using Excimer Laser Ablated Polycarbonate Molds

Ceramic surface microstructuring is a rapidly growing field with a variety of applications in tribology, wetting, biology, and so on. However, there are limitations to large-area microstructuring and fabrication of three-dimensional (3D) micro free forms. Here, we present a route to obtain intricate surface structures through in situ slip casting using polydimethylsiloxane (PDMS) negative molds which are replicated from excimer laser ablated polycarbonate (PC) master molds. PC sheets are ablated with a nanosecond KrF (λ = 248 nm) excimer laser mask projection system to obtain micron-scale 3D surface features over a large area of up to 3 m(2). Complex surface structures that include 3D free forms such as 3D topography of Switzerland, shallow structures such as diffractive optical elements (60 nm step) and conical micropillars have been obtained. The samples are defect-free produced with thicknesses of up to 10 mm and 120 mm diameter. The drying process of the slip cast alumina slurry takes place as a one-dimensional process, through surface evaporation and water permeation through the PDMS membrane. This allows homogeneous one-dimensional shrinkage during the drying process, independent of the sample's lateral dimensions. A linear mass diffusion model has been proposed to predict and explain the drying process of these ceramic colloidal suspensions. The calculated drying time is linearly proportional to the height of the slurry and the thickness of the negatively structured PDMS and is validated by the experimental results. An experimentally observed optimum Sylgard PDMS thickness range of ∼400 μm to 1 mm has achieved the best quality microstructured green compacts. Further, the model predicts that the drying time is independent of the microstructured areas and was validated using experimental observations carried out with microstructured areas of 300 mm(2), 1200 mm(2), and 120 cm(2). Therefore, in principle, the structures can be further replicated in areas up to 3 m(2) with the same drying time for the same slurry height. The surface-structured ceramics display interesting wetting properties, for example, eicosane-coated mesoporous microstructured alumina shows superhydrophobic behavior. Additionally, ceramic bulk samples could be further used as second-generation very hard and low-wear molds for further microfabrication.

Development of a DNA Macroarray for the Detection and Identification of Fungal Pathogens Causing Decline of Young Grapevines

Young vine decline (YVD) is a complex disease caused by at least 51 different fungi and responsible for important economic losses to the grapevine industry worldwide. YVD fungi are known to occur in planting material. Hence, detection prior to planting is critical to assure longevity of newly established vineyards. A DNA macroarray based on reverse dot-blot hybridization containing 102 oligonucleotides complementary to portions of the β-tubulin region was developed for detection of YVD fungi. Specificity of the array was first evaluated against 138 pure fungal cultures representing 72 different taxa from nine genera, including 37 YVD species. In total, 61 species, including 34 YVD pathogens, were detected and identified by the array. The detection limit of the array was below 0.1 pg of genomic DNA. The array was validated against artificially inoculated canes and soil and commercial planting material, with the latter showing a high incidence of YVD fungi in nursery plants otherwise not detected by traditional plating and culturing. This DNA array proved to be a rapid and specific tool to simultaneously detect and identify most YVD fungi in a single test, which has the potential to be used in commercial diagnostics or by the grapevine nursery industry to determine the health status of the planting material.

Continuous Polyol Synthesis of Metal and Metal Oxide Nanoparticles Using a Segmented Flow Tubular Reactor (SFTR)

Over the last years a new type of tubular plug flow reactor, the segmented flow tubular reactor (SFTR), has proven its versatility and robustness through the water-based synthesis of precipitates as varied as CaCO3, BaTiO3, Mn(1-x)NixC2O4·2H2O, YBa oxalates, copper oxalate, ZnS, ZnO, iron oxides, and TiO2 produced with a high powder quality (phase composition, particle size, and shape) and high reproducibility. The SFTR has been developed to overcome the classical problems of powder production scale-up from batch processes, which are mainly linked with mass and heat transfer. Recently, the SFTR concept has been further developed and applied for the synthesis of metals, metal oxides, and salts in form of nano- or micro-particles in organic solvents. This has been done by increasing the working temperature and modifying the particle carrying solvent. In this paper we summarize the experimental results for four materials prepared according to the polyol synthesis route combined with the SFTR. CeO2, Ni, Ag, and Ca3(PO4)2 nanoparticles (NPs) can be obtained with a production rate of about 1-10 g per h. The production was carried out for several hours with constant product quality. These findings further corroborate the reliability and versatility of the SFTR for high throughput powder production.

HIV testing of construction workers in the Western Cape, South Africa

With an infection rate estimated at 14%, the South African construction industry is one of the economic sectors most adversely affected by the HIV/AIDS pandemic. Construction workers are considered a high-risk group. The provision and uptake of voluntary counselling and testing (VCT) is critical to reducing transmission rates. This study examined the testing behaviour of site-based construction workers in terms of demographic and lifestyle risk behaviour characteristics to help inform better strategies for work-based interventions by construction firms. A total of 512 workers drawn from six firms operating on 18 construction sites in the Western Cape province participated in the study. Twenty-seven per cent of the participants reported never having been tested for HIV. Results indicate that females (aOR = 4.45, 95% CI, 1.25-15.82), older workers (aOR = 1.40, 95% CI, 1.08-1.81), permanent workers (aOR = 1.67, 95% CI, 1.11-2.50) and workers whom had previously used a condom (aOR = 1.93, 95% CI, 1.02-3.65) were significantly more likely to have been tested. Ethnicity was not significantly related to prior testing. Identification of these subgroups within the industry has implications for the development of targeted work-based intervention programmes to promote greater HIV testing among construction workers in South Africa.

Physicochemical characterization of nebulized superparamagnetic iron oxide nanoparticles (SPIONs)

BACKGROUND

Aerosol-mediated delivery of nano-based therapeutics to the lung has emerged as a promising alternative for treatment and prevention of lung diseases. Superparamagnetic iron oxide nanoparticles (SPIONs) have attracted significant attention for such applications due to their biocompatibility and magnetic properties. However, information is lacking about the characteristics of nebulized SPIONs for use as a therapeutic aerosol. To address this need, we conducted a physicochemical characterization of nebulized Rienso, a SPION-based formulation for intravenous treatment of anemia.

METHODS

Four different concentrations of SPION suspensions were nebulized with a one-jet nebulizer. Particle size was measured in suspension by transmission electron microscopy (TEM), photon correlation spectroscopy (PCS), and nanoparticle tracking analysis (NTA), and in the aerosol by a scanning mobility particle sizer (SMPS).

RESULTS

The average particle size in suspension as measured by TEM, PCS, and NTA was 9±2 nm, 27±7 nm, and 56±10 nm, respectively. The particle size in suspension remained the same before and after the nebulization process. However, after aerosol collection in an impinger, the suspended particle size increased to 159±46 nm as measured by NTA. The aerosol particle concentration increased linearly with increasing suspension concentration, and the aerodynamic diameter remained relatively stable at around 75 nm as measured by SMPS.

CONCLUSIONS

We demonstrated that the total number and particle size in the aerosol were modulated as a function of the initial concentration in the nebulizer. The data obtained mark the first known independent characterization of nebulized Rienso and, as such, provide critical information on the behavior of Rienso nanoparticles in an aerosol. The data obtained in this study add new knowledge to the existing body of literature on potential applications of SPION suspensions as inhaled aerosol therapeutics.

Grapevine Trunk Diseases in British Columbia: Incidence and Characterization of the Fungal Pathogens Associated with Black Foot Disease of Grapevine

Black foot disease of grapevines, caused by several fungal species in the genera Campylocarpon, Cylindrocarpon, Cylindrocladiella, and Ilyonectria, causes significant economic losses to the grapevine industry worldwide. This study represents the first attempt to identify and characterize the fungal pathogens associated with black foot disease of grapevines in British Columbia (BC). Field surveys conducted throughout all grape-growing regions in BC that included assessment of foliar symptomatology and isolations from symptomatic vines showed Cylindrocarpon/Ilyonectria spp. occurred in 32 of 90 (35.5%) young vineyards surveyed (≤8 year old) and in 41 of 215 (19%) samples collected. In 20 of the 41 (48.8%) samples, Cylindrocarpon/Ilyonectria spp. were the sole fungi isolated from symptomatic tissue. In the rest of the samples, black foot fungi were found to primarily coexist with fungal taxa associated with Petri disease of grapevines. Colony and conidia phenotypical characterization, along with DNA analyses of the internal transcribed spacer region (ITS1-5.8S-ITS2) of the rDNA, and part of the β-tubulin and translation elongation factor 1-α genes, revealed five different black foot fungi occurring in declining young vines in BC, namely Cylindrocarpon pauciseptatum, Ilyonectria liriodendri, Ilyonectria macrodidyma, Ilyonectria robusta, and Ilyonectria torresensis. Pathogenicity studies showed all five species to be highly virulent in the grapevine rootstock cultivar 3309C. Overall, I. liriodendri and I. macrodidyma were the most virulent species when inoculated in Vitis vinifera 'Chardonnay' and rootstock 3309C.

Grapevine Trunk Diseases in British Columbia: Incidence and Characterization of the Fungal Pathogens Associated with Esca and Petri Diseases of Grapevine

Esca and Petri disease are two economically important grapevine diseases worldwide. This study reports for the first time the occurrence of both diseases on grapevines in British Columbia (BC) and subsequently in Canada. Visual assessment of 55,699 vines in 118 vineyards revealed a low incidence of esca with only 104 (0.2%) vines showing foliar symptoms. Young vine decline (YVD) was observed in 1,910 (7.8%) of 24,487 monitored young vines and in 52 (8%) of 654 young vines used as re-plants in mature vineyards. In 8 of 51 monitored young vineyards, YVD-affected vines ranged between 15 and 55%. Morphological studies along with DNA analyses of the ITS1-5.8S-ITS2, and part of the β-tubulin, actin, and translation elongation factor 1-α gene regions, allowed us to identify Cadophora luteoolivacea, Phaeomoniella chlamydospora, Phaeoacremonium iranianum, Togninia fraxinopennsylvanica, Togninia minima, and the novel species Phaeoacremonium canadense and Phaeoacremonium roseum from esca and Petri disease infected vines in BC. This study includes for the first time the EF1-α DNA marker in Phaeoacremonium spp. delineation. Pathogenicity studies showed all seven fungi to cause vascular symptoms similar to those observed in esca and Petri disease infected vines. Additionally, the "tiger-stripes" foliar symptom of esca was successfully reproduced when healthy potted vines were inoculated with BC isolates of Pa. chlamydospora, Pm. canadense, Pm. iranianum, T. fraxinopennsylvanica, and T. minima.

Modeling the Design Team as a Temporary Management Structure: Reality versus Theory

The focus of the cost management literature is almost exclusively on technical issues, with scant attention to its social, political and organisational dimensions. In this paper the authors document research examining the design team as a temporary management structure, with emphasis on the efficacy of the cost management system as a vehicle for attaining client objectives with respect to time, cost and quality. Soft systems methodology is used to explore the perceptions of stakeholders to the cost management system, thus developing conceptual models of the theory and practice of cost management. Significant differences were found to exist between the perceptions of individual stakeholders concerning design team participants, participants’ roles, and the very purpose of the cost management system. Recommendations are made for structural, attitudinal and procedural changes to the cost management system in order to facilitate its effective functioning in the achievement of the client’s needs and objectives.

Contribution of aggregation to the growth mechanism of seeded calcium carbonate precipitation in the presence of polyacrylic acid

Our work investigates the precipitation mechanism of a seeded calcium carbonate reaction, by using cryogenic TEM to observe the early stages of the reaction. The early precipitation of a hydrated phase is proposed as an intermediate phase before transformation into calcite. Thermodynamic modeling in conjunction with pH, surface potential measurements, and colloidal stability modeling demonstrate that calcite growth is dominated by agglomeration. This is in agreement with the cryogenic TEM observations, which suggest oriented attachment dominates early aggregation. The final stage of the reaction is described by a ripening mechanism that is significantly inhibited when high concentrations of polyacrylic acid (PAA) are used. The different concentrations of PAA lead to significant differences in the final particle substructure observed using cross section TEM. At low PAA concentrations, single crystal particles result, coherent with the proposed early oriented attachment mechanism and interfacial energy calculations. A core shell model is proposed for high PAA concentrations, whereas internal ripening of nanosized pores has been observed for low PAA concentrations, suggesting trapped solvent during the rapid initial particle formation at the relatively high supersaturations (S = 30) investigated.

Control of morphology and nanostructure of copper and cobalt oxalates: effect of complexing ions, polymeric additives and molecular weight

Precipitated oxalates are often nanostructured and can be used as precursors for nanostructured oxides for different applications. The modification of the particle shape and nanostructures of both copper and cobalt oxalates has been demonstrated using polymeric additives or complexing counter-ions. In the case of cobalt oxalate the characteristic elongated rod particle shape (axial ratio of 10) can be modified by using polymethymethacrylate (PMMA) to produce particles with lower axial ratios of 2, through cubes all the way to platelets (axial ratio 0.2). The PMMA inhibits the growth of the particles along the [101] direction more and more strongly as the concentration of the polymer increases. The crystallite size from XRD line broadening is not modified by the PMMA indicating that the PMMA does not influence the nucleation and growth but modifies the aggregation kinetics. Copper oxalates precipitated in the presence of different cellulose derived polymers with different molecular weights and functional groups (methyl and propyl) showed sensitivity to both molecular weight and functional group. Higher molecular weights did not influence the copper oxalate particle shape, whereas methyl cellulose gave elongated particles and propyl celluloses gave platelet like particles. Copper oxalate precipitated in the presence of acetate counter ions gave platelets with an axial ratio of 0.15 compared to the cushion-like morphology (axial ratio 0.5). The primary crystallites were more elongated along the [001] direction in the presence of acetate, modifying the proportion of the hydrophobic and hydrophilic surfaces and hence influencing the aggregation kinetics and particle shape. The copper and cobalt oxalate particle formation seems to be dominated by the primary particle aggregation with the different additives interacting specifically with different crystallographic faces of the primary particles. By tuning this interaction particles with different shapes and substructures can be formed.

Innovative high-surface-area CuO pretreated cotton effective in bacterial inactivation under visible light

This study presents the first report on enhanced bacterial inactivation of E. coli by RF-plasma pretreated cotton with high-surface-area CuO powders compared with nonpretreated cotton textiles. The high-surface-area CuO (65 m/g) powder was fully characterized. The E. coli inactivation proceeded in the dark and was accelerated under visible and sunlight irradiation even at very low levels of visible light irradiation. The effect the RF-plasma pretreatment of the cotton on the binding of CuO, applied light dose, the amount of CuO loading and initial E. coli concentration on the inactivation kinetics of E. coli is reported in detail.

Value management practice by South African quantity surveyors

Purpose

This paper aims to investigate the nature and extent of value management (VM) practice by professional quantity surveyors in South Africa. The survey explores practitioners' awareness and understanding of VM and the nature and extent of the use of VM techniques within their organisations.

Design/methodology/approach

A web‐based, online questionnaire survey is employed to establish VM practice by South African registered quantity surveyors. Descriptive statistics are used to analyse the survey response data.

Findings

The results suggest that, while VM (and more particularly its value engineering antecedent) is generally known among quantity surveyors in South Africa, it is less widely practiced. VM is seen predominantly as a cost reduction tool. This misperception, and the lack of awareness of the potential benefits of VM, must be remedied if quantity surveyors in South Africa are to provide clients with services that meet world's best practice standards. Quantity surveyors also need to know what those standards are.

Practical implications

Refresher courses in contemporary VM theory and practice are recommended, as well as exploration of the impacts on VM of other techniques such as risk, quality and environmental management.

Originality/value

The findings are important given the increasing globalization of construction services, especially given the international ties between designers, quantity surveyors and other built environment professionals.