Occupational exposure and health risks of volatile organic compounds of hotel housekeepers: Field measurements of exposure and health risks

Hotel housekeepers represent a large, low-income, predominantly minority, and high-risk workforce. Little is known about their exposure to chemicals, including volatile organic compounds (VOCs). This study evaluates VOC exposures of housekeepers, sources and factors affecting VOC levels, and provides preliminary estimates of VOC-related health risks. We utilized indoor and personal sampling at two hotels, assessed ventilation, and characterized the VOC composition of cleaning agents. Personal sampling of hotel staff showed a total target VOC concentration of 57 ± 36 µg/m³ (mean ± SD), about twice that of indoor samples. VOCs of greatest health significance included chloroform and formaldehyde. Several workers had exposure to alkanes that could cause non-cancer effects. VOC levels were negatively correlated with estimated air change rates. The composition and concentrations of the tested products and air samples helped identify possible emission sources, which included building sources (for formaldehyde), disinfection by-products in the laundry room, and cleaning products. VOC levels and the derived health risks in this study were at the lower range found in the US buildings. The excess lifetime cancer risk (average of 4.1 × 10⁻⁵) still indicates a need to lower exposure by reducing or removing toxic constituents, especially formaldehyde, or by increasing ventilation rates.     

Nuclear Magnetic Resonance of Physisorbed 129Xe Used as a Probe to Investigate Porous Solids

Xenon is an inert gas with a large electronic environment that makes it sensitive to any interaction, even physical. In the case of ¹²⁹Xe isotope (spin 1/2), the resulting electronic perturbation is directly transmitted to the nucleus and, therefore, affects the nuclear magnetic resonance chemical shift. In this review, we report exhaustively up to 1996 the many applications of this technique in both fundamental and applied research in the fields of microporous and mesoporous solids.     

Relation between the redox state of iron-based nanoparticles and their cytotoxicity toward Escherichia coli

Iron-based nanoparticles have been proposed for an increasing number of biomedical or environmental applications although in vitro toxicity has been observed. The aim of this study was to understand the relationship between the redox state of iron-based nanoparticles and their cytotoxicity toward a Gram-negative bacterium, Escherichia coli. While chemically stable nanoparticles (gammaFe2O3) have no apparent cytotoxicity, nanoparticles containing ferrous and, particularly, zerovalent iron are cytotoxic. The cytotoxic effects appear to be associated principally with an oxidative stress as demonstrated using a mutant strain of E. coli completely devoid of superoxide dismutase activity. This stress can result from the generation of reactive oxygen species with the interplay of oxygen with reduced iron species (Fe(II) and/or Fe(0)) or from the disturbance of the electronic and/or ionic transport chains due to the strong affinity of the nanoparticles for the cell membrane.     

A Simple and Fast HPLC Method to Determine Lycopene in Foods

Carotenoids, among which lycopene—the principal pigment found in tomatoes—are lipophilic compounds which play a very important role in human health and nutrition. They are also recognised as strong antioxidants due to their ability to trap singlet oxygen and eliminate the peroxyl radical. The availability of reliable information on lycopene content of foods is essential both for the evaluation of diet and for epidemiological research relating the intake of lycopene. This paper describes a simple and fast HPLC/UV method for lycopene determination in a wide range of food products. All-E-lycopene together with its Z isomers were eluted isocratically using a carotenoid C30 reversed-phase column. The in-house validated HPLC method had a limit of quantification of 60 ng lycopene/g product and high precision and accuracy. The analytical method was successfully applied to several food products such as raw vegetables and fruits and also processed foods. Tomato and tomato-containing products contained the highest amounts of lycopene. While raw foods and minimally processed foods contained above 94% of all-E-lycopene, processed foods (such as soups, pasta sauces, pizza and cheese) contained from 76% to 87% of all-E-lycopene.     

Response of RC Beams Strengthened with CFRP Laminates and Subjected to a High Rate of Loading

Results are presented of an experimental program undertaken to investigate the effects of strain rate on the behavior of reinforced concrete (RC) beams strengthened with carbon fiber-reinforced polymer (CFRP) laminates. Nine 3-m RC concrete beams, one unstrengthened, four strengthened with S-type CFRP laminates, and four strengthened with R-type laminates, were loaded under four different loading schedules. The stroke rates ranged from 0.0167 mm∕s (slow rate of loading) to 36 mm∕s (fast rate of loading). This induced a strain rate in the CFRP of 2.96 με∕s (slow rate) to 6,930 με∕s (fast rate). Some beams were subjected to either 1 or 12 cycles of loading prior to a fast rate of loading to failure. The rapidly loaded beams showed an increase of approximately 5% in capacity, stiffness, and energy absorption. Ductility and the mode of failure were not directly affected by the change in loading rate. Precycled beams performed similarly to the beams loaded monotonically to failure but showed a 10% increase in service stiffness and a 10% loss in energy absorption. A finite-element, layered analysis is presented to predict the moment-curvature response of CFRP strengthened RC beams. The model includes the effects of strain rate and correlates well with the experimental data.     

Canadian Bridge Design Code Provisions for Fiber-Reinforced Structures

This paper presents a synthesis of the design provisions of the Canadian Highway Bridge Design Code for fiber-reinforced structures. These include structures reinforced with fiber-reinforced polymer and fiber-reinforced concrete (FRC). The provisions apply to fully, or partially, prestressed concrete beams and slabs, non-prestressed concrete beams, slabs, and deck slabs, FRC deck slabs of slab-on-girder bridges, stressed wood decks, and barrier walls. Test methods to confirm the tensile strength of fiber-reinforced polymer and the postcracking strength of FRC are given.     

A unified short-channel compact model for cylindrical surrounding-gate MOSFET

For the first time, a continuous and explicit model valid in all operating regions, for undoped short-channel cylindrical gate-all-around (GAA) MOSFETs, is presented in this study. From a two-dimensional analysis, the threshold voltage roll-off, the drain-induced barrier lowering (DIBL) and the subthreshold swing are explicitly modeled. Short-channel effects are then implemented into a continuous drain-current model based on an effective surface potential approach using the gradual channel approximation. Improving the model behavior in the saturation operating region by accounting the channel pinch-off displacement, channel length modulation is studied and implemented as well. Analytical results are compared to TCAD-Atlas numerical simulations and validate the short-channel model in all operating modes making it suitable for circuit design simulations.     

Hyperpolarized 129Xe NMR and N2 sorption cross-investigations of the crystallization of Al-SBA-15 amorphous walls into ZSM-5 type materials

The present work deals with the study of the parameters which govern the partial conversion of the amorphous walls of Al-SBA-15 supports into ZSM-5 type deposits under alkaline aqueous conditions. The influence of the mode of insertion of aluminium into Al-SBA-15 as well as of the quantities of ammonium fluoride and ZSM-5 template (TPABr) has been investigated. XRD and nitrogen sorption data indicate that the mesopore network is very fragile under the conditions required for the crystallization of ZSM-5. A compromise was found by using a TPABr/Al molar ratio lower than 1, thus affording materials containing both mesopores and zeolite-type micropores. The combined use of hyperpolarized (HP) ¹²⁹Xe NMR and α-plot studies gave evidence for the ZSM-5 nature of the micropores as well as some indications in favour of the interconnection of the different pore networks. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Nonverbal indices of arousal in group psychotherapy.

Examined psychometric properties of a nonverbal measure of arousal in psychotherapy (J. K. Burgoon et al, 1989) used with depressed clients in 2 types of group psychotherapy: experiential (n?=?18) and cognitive (n?=?13). Results indicate that both general and specific aspects of emotional arousal can be reliably rated from nonverbal behaviors. Vocalic tension, nervous vocalizations and laughter, kinesic random movement, and vocal expressiveness were associated with higher global arousal. A 2nd study looked at the relationship between nonverbal arousal and within-session benefits in the 2 group psychotherapies. A depressed S experiencing positive response to therapy and one experiencing a poor response were studied from each type of therapy. Different patterns of arousal characterized the different group therapy modalities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

First evidence of interconnected micro and mesopores in CMK-3 materials

The porous structure and the pore interconnections of mesoporous carbon of CMK-3 type have been studied by means of hyperpolarized ¹²⁹Xe NMR spectroscopy.Parallel studies of purely microporous carbon and CMK-3 have unambiguously revealed the presence of micropores inside the CMK-3 structure. In addition, ¹²⁹Xe 2D-exchange NMR experiments have clearly shown direct exchange of Xe atoms between the micro and the mesoporosity. This indicates the presence of micropores inside the carbon rods constituting the mesoporous structure of CMK-3 materials.