Semivolatile organic compounds in French schools: Partitioning between the gas phase,airborne particles and settled dust

The indoor environmental quality in classrooms can largely affect children's daily exposure to indoor chemicals in schools. To date, there has not been a comprehensive study of the concentrations of semivolatile organic compounds (SVOCs) in French schools. Therefore, the French Observatory for Indoor Air Quality (OQAI) performed a field study of SVOCs in 308 nurseries and elementary schools between June 2013 and June 2017. The concentrations of 52 SVOCs, including phthalates, polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), synthetic musks, and pesticides, were measured in air and settled dust (40 SVOCs in both air and dust, 12 in either air or dust). The results showed that phthalates had the highest concentrations among the SVOCs in both the air and dust. Other SVOCs, including tributyl phosphate, fluorene, phenanthrene, gamma-hexachlorocyclohexane (gamma-HCH, lindane), galaxolide, and tonalide, also showed high concentrations in both the air and dust. Theoretical equations were developed to estimate the SVOC partitioning between the air and settled dust from either the octanol/air partition coefficient or the boiling point of the SVOCs. The regression constants of the equations were determined using the data set of the present study for phthalates and PAHs.     

Final Shape of Precision Molded Optics: Part I—Computational Approach,Material Definitions and the Effect of Lens Shape

Coupled thermomechanical finite element models were developed in ABAQUS to simulate the precision glass lens molding process, including the stages of heating, soaking, pressing, cooling and release. The aim of the models was the prediction of the deviation of the final lens profile from that of the mold, which was accomplished to within one-half of a micron. The molding glass was modeled as viscoelastic in shear and volume using an n-term, prony series; temperature dependence of the material behavior was taken into account using the assumption of thermal rheological simplicity (TRS); structural relaxation as described by the Tool-Narayanaswamy-Moynihan (TNM)-model was used to account for temperature history dependent expansion and contraction, and the molds were modeled as elastic taking into account both mechanical and thermal strain. In Part I of this two-part series, the computational approach and material definitions are presented. Furthermore, in preparation for the sensitivity analysis presented in Part II, this study includes both a bi-convex lens and a steep meniscus lens, which reveals a fundamental difference in how the deviation evolves for these different lens geometries. This study, therefore, motivates the inclusion of both lens types in the validations and sensitivity analysis of Part II. It is shown that the deviation of the steep meniscus lens is more sensitive to the mechanical behavior of the glass, due to the strain response of the newly formed lens that occurs when the pressing force is removed.     

Machine learning and statistical models for predicting indoor air quality

Indoor air quality (IAQ), as determined by the concentrations of indoor air pollutants, can be predicted using either physically based mechanistic models or statistical models that are driven by measured data. In comparison with mechanistic models mostly used in unoccupied or scenario‐based environments, statistical models have great potential to explore IAQ captured in large measurement campaigns or in real occupied environments. The present study carried out the first literature review of the use of statistical models to predict IAQ. The most commonly used statistical modeling methods were reviewed and their strengths and weaknesses discussed. Thirty‐seven publications, in which statistical models were applied to predict IAQ, were identified. These studies were all published in the past decade, indicating the emergence of the awareness and application of machine learning and statistical modeling in the field of IAQ. The concentrations of indoor particulate matter (PM_2.5 and PM₁₀) were the most frequently studied parameters, followed by carbon dioxide and radon. The most popular statistical models applied to IAQ were artificial neural networks, multiple linear regression, partial least squares, and decision trees.     

Effect of Replacement of As by Ge and Sb on the Photo-Response under Near Infrared Femtosecond Laser Irradiation in As-based Sulfide Glasses

Bulk glasses having the compositions As₄₂S₅₈, As₃₆Sb₆S₅₈, and As₃₆Ge₆S₅₈ have been irradiated at 800 nm using a femtosecond-pulsed laser to determine the relationship between composition and photo-response. Localized variation in the glass volume (photo-expansion) has been determined through interferometric measurements of surface exposures, whereas induced refractive index change (photo-darkening) was determined from the diffraction efficiency of subsurface direct-written phase gratings. To understand the compositional dependence of the photo-response, the linear and nonlinear optical properties and structure of the unexposed glasses have been compared. The ablation threshold is shown to be controlled by variation of the nonlinear absorption, related to shifts of the absorption band gap with exchange of As by Ge or Sb. Changes in the unexposed network structure show that partial replacement of As by Ge or Sb induces an increased number of As–As bonding defects in the glass, particularly in the form of As₄S₄ molecular units which become polymerized into the network, impacting the photo-modification process. The Ge was found to induce an increase in the ablation threshold, and enhance both photo-darkening and photo-expansion effects, whereas Sb was shown to decrease ablation threshold and inhibit photo-darkening while enhancing photo-expansion.     

Urinary Metabolic Phenotyping Reveals Differences in the Metabolic Status of Healthy and Inflammatory Bowel Disease (IBD) Children in Relation to Growth and Disease Activity

Background: Growth failure and delayed puberty are well known features of children and adolescents with inflammatory bowel disease (IBD), in addition to the chronic course of the disease. Urinary metabonomics was applied in order to better understand metabolic changes between healthy and IBD children. Methods: 21 Pediatric patients with IBD (mean age 14.8 years, 8 males) were enrolled from the Pediatric Gastroenterology Outpatient Clinic over two years. Clinical and biological data were collected at baseline, 6, and 12 months. 27 healthy children (mean age 12.9 years, 16 males) were assessed at baseline. Urine samples were collected at each visit and subjected to ¹H Nuclear Magnetic Resonance (NMR) spectroscopy. Results: Using ¹H NMR metabonomics, we determined that urine metabolic profiles of IBD children differ significantly from healthy controls. Metabolic differences include central energy metabolism, amino acid, and gut microbial metabolic pathways. The analysis described that combined urinary urea and phenylacetylglutamine—two readouts of nitrogen metabolism—may be relevant to monitor metabolic status in the course of disease. Conclusion: Non-invasive sampling of urine followed by metabonomic profiling can elucidate and monitor the metabolic status of children in relation to disease status. Further developments of omic-approaches in pediatric research might deliver novel nutritional and metabolic hypotheses.     

Addressing the Skills Shortage Problem of the South African Tourism and Hospitality Industry: An Evaluation of the Effectiveness of the 2007/2008 SA Host Training Program in the Western Cape Province

The issue of skills shortage has been central to the discussions on economic growth and development in South Africa. Education and skills development are listed as one of the seven “Priorities for Intervention” constraints in the 2006 Accelerated and Shared Growth Initiative for South Africa. The objectives of this study were to establish the competency levels of tourism/hospitality industry employees on a list of nontechnical hospitality skills, assess the skills gap between employer expectations and employee performance on these skills, evaluate the impact of the 2007/2008 SA Host training program in reducing that gap and improving employee skills. The results showed an improvement in employee performance and a reduction in the skills gaps after the training.     

Design,processing, and characterization of an optical core-bioactive clad phosphate fiber for biomedical applications

The aim of this study was to fabricate a bioactive optical fiber able to monitor “in situ” its reaction with the body through changes in its optical properties. Core and cladding preforms were prepared with the composition (97.25*(0.50P₂O₅-0.40SrO-0.10Na₂O)-2.5ZnO-0.25Er₂O₃) and (98.25*(0.50P₂O₅-0.40SrO-0.10Na₂O)-1.75ZnO) (in mol%), respectively, and successfully drawn into a multimode core/clad optical fiber. Optical and near-Infrared images assessed the proper light guiding properties of the fiber. The fibers favor the precipitation of a Ca-P reactive layer at its surface concomitant with a reduction in the fiber diameter, when immersed in SBF, often assigned as a sign of bioactivity. It is clearly shown here that the bio-response of the fiber upon immersion in SBF can be tracked from the decrease in the intensity of the Er³⁺ ions emission at 1.5 µm. This confirms that the newly developed optical fiber, which combines good optical properties with a suitable bioactive behavior, is a promising platform for the development of novel biomedical devices for biophotonic and photomedical applications. Finally, the successful splicing of the newly developed fiber with commercial optical fibers was an evidence of the possibility to integrate the newly developed phosphate fiber within existing components used in the field of biomedicine.     

Characterization of biodegradable core–clad borosilicate glass fibers with round and rectangular cross-section

Here, we report on core–clad bioactive borosilicate fibers, that we have prepared both with round and rectangular cross-section profile. The exposed approach, which relies on the stacking and drawing of glass slabs, demonstrates our ability to develop bioactive-based glass fibers with tailored cross-section profiles. Tens-of-meters-long fibers were successfully drawn, although suffering from elevated losses in the case of the rectangular ones. The response of the fibers in simulated body fluid was studied for both geometries. We found that a round cladding can act as protective layer, tempering effects of the corrosion. We also noticed that rectangular fibers are more prone to degradation, the enhanced corrosion beginning from their sharp corners as they accumulated residual tensile stress during drawing. To the best of our knowledge, this is the first report on the effect of residual tensile stresses from surface tension deformations applied to the corrosion of rectangular fibers. As geometry plays a critical role on the biodegradation behavior of the fiberglass, we believe the enclosed results could lead to the design of fiber devices with tailored cross-section profile in order to tune their rate of degradation on solely based geometrical effects.