Maximum Exposure Duration Research Articles

Performance of a Ship-Based Cupronickel Alloy in Exposure Conditions of Arabian Seawater-A Comparative Study.

Cupronickel-based alloys are widely known for their excellent resistance against aqueous corrosion, however, they can be susceptible to corrosion at accelerated rates and premature failure when exposed to a polluted or brackish seawater medium, even for short-term exposure durations. This unfamiliar corrosion behavior may be a result of the formation of an unprotected corrosion film during the early exposure durations. The paper investigates the corrosion phenomenon in cupronickel 90/10 alloy, by exposing the coupons in two different seawater compositions in the Arabian Sea region. Corrosion losses were investigated on the experimental coupons in a submerged position, for a maximum exposure duration of 150 days, using the conventional weight loss method and a new dimensional metrology-based measurement technique. Additionally, in this research the tubes of a marine heat exchanger having similar material that failed prematurely during operation in the Arabian Sea were also investigated for corrosion losses, followed by the characterization of the corrosion deposits using following analytical techniques: SEM, EDS, XRD and Raman Scattering. The experimental results showed significantly higher corrosion losses on coupons exposed to seawater site rich in pollutants and nutrients including dissolved inorganic nitrogenous compounds, compared to those subjected to a natural seawater solution in corrosion tanks maintained in a controlled environment.

In English

Purifying aqueous solutions from radioactive contamination is an extremely relevant scientific topic today. Many organic and inorganic adsorbents can be recommended for the adsorption of heavy metal ions and radionuclides from aqueous solutions, or as carriers for storage and disposal of radioactive waste. Since radionuclides are sources of ionizing radiation, the radiation resistance of the adsorbent is an important characteristic. These studies aim to investigate the titanium silicate behavior and its adsorption properties' changes or their invariability in the field of intense β-radiation. Experimental techniques describe the synthesis of titanium silicate adsorbent by sol-gel method and the study of its adsorption capacity toward Ba2+ cations. The adsorption of Ba2+ cations was investigated under batch conditions with neutral pH of the solution. Initial and residual concentrations of Ba2+ cations were controlled by direct complexometric titration with Na-EDTA with Eriochrom Black T as an indicator. The study of the radiation resistance of the adsorbent to high-energy β-radiation was performed using a 90Sr-90Y β- - source “Sirius” installed in the Microtron Laboratory of the Uzhhorod National University. The distance from the source to the adsorbent samples was 20 cm. The flux of electrons at this distance was 108 el/cm2‧per second. The maximum energy of beta particles was 0.456 MeV for 90Sr and 2.28 MeV for 90Y. The maximum duration of exposure was 21 days, which corresponds to 1310 Gy. Raman spectroscopy of irradiated and nonirradiated samples of TiSi was performed using a Raman spectrometer XploRA PLUS installed in the Center for Collective Use of Scientific Equipment “Laboratory of Experimental and Applied Physics” of Uzhhorod National University. Results consist of kinetic of Ba2+ adsorption by titanium silicate and irradiated titanium silicate; isotherm of Ba2+ adsorption and Raman spectrum of nonirradiated, irradiated titanium silicate (TiSi) and TiSi after Ba2+ adsorption. Results showed that the value of the maximal adsorption was 140.5±9.2 mg/g (6.55 %) under a confidence level of 95 %. The adsorption values of barium ions by irradiated and non-irradiated titanium silicate coincide. This indicates that the adsorption properties of this adsorbent do not change under the influence of such a radiation dose. The Raman spectra of irradiated and non-irradiated titanium silicate coincide, while they do not identify free radicals, or ionic formations, which would indicate a change in the properties of the adsorbent under the influence of beta radiation. It can be argued that this adsorbent is radiation-resistant to beta-radioactivity, with a radiation dose of 1310 Gy. The main conclusion of the present work is that the studied sample of titanium silicate is radiation-resistant. It can withstand a radiation dose of 1310 Gy without changing its adsorption properties. Titanium silicate can be used for the adsorption of strontium radionuclides, it can be a carrier for the disposal of radioactive waste.

Toxic effect of the titanium dioxide rutile form on the morphological characteristics of the immune system organs

The aim. To study the effect of the rutile form of titanium dioxide upon its oral administration on the morphological and functional state of the organs of the immune system of rats. Materials and methods. In this work, using classical morphological approaches and specific markers: proliferation - Ki-67, PCNA, apoptosis - protein p53 and macrophages - CD68, which make it possible to adequately identify not only the cells themselves, but also their functional state, a study of the spleen and thymus of rats after oral administration (10 mg/kg animal body weight, 28 days) of a nanodispersed form of TiO2 (rutile form, 40-60 nm) obtained by diluting TiO2 powder in distilled water was carried out. Aggregation of nanoparticles was prevented by treatment of a suspension of nanodispersed TiO2 in an ultrasonic bath. Rats of the control group were orally administered with distilled water in the same volume. Results. With oral administration of the rutile form of nanodispersed TiO2, a moderate accidental involution of the thymus is observed, a reduction in the white pulp of the spleen, due to a decrease in the proliferative potential and an increase in apoptosis. The revealed morphofunctional changes in lymphoid organs can be interpreted from the standpoint of induced secondary immunodeficiency that develops against the background of exposure to rutile TiO2 NPs. Limitations. When studying the effect of titanium dioxide (rutile, 40-60 nm, 10 mg/kg of animal body weight) on the morphological characteristics of the immune defense organs, the sample size was 12 Wistar rats, the maximum duration of exposure was 28 days. Conclusion. The detected morphofunctional changes in the lymphoid organs can be interpreted from the position of induced secondary immunodeficiency, developing against the background of exposure to NPS TiO2 of the rutile modification.

Adverse events of special interest in clinical trials of rheumatoid arthritis, psoriatic arthritis, ulcerative colitis and psoriasis with 37 066 patient-years of tofacitinib exposure

ObjectivesTo analyse adverse events (AEs) of special interest across tofacitinib clinical programmes in rheumatoid arthritis (RA), psoriatic arthritis (PsA), ulcerative colitis (UC) and psoriasis (PsO), and to determine whether the...

Postural Activity During Use of a Head-Mounted Display: Sex Differences in the “Driver–Passenger” Effect

Motion sickness is common in virtual environments. The risk of motion sickness varies widely between individuals and across situations. The subjective experience of motion sickness often is preceded by distinctive patterns of movement in the control of head and body posture. Previous research has documented reliable sex differences in the kinematics of postural activity, as well as reliable differences in postural activity between participants who were in control of a virtual vehicle and participants who were not. We asked whether postural precursors of motion sickness would simultaneously be influenced by individual and situational factors. We analyzed movement of the head and torso while seated participants were exposed to a driving video game presented through a head-mounted display. Half of the participants were women, and half were men. Using a yoked-control design, half of the participants controlled the virtual vehicle (Drivers), whereas half watched previously recorded vehicle trajectories (Passengers). The maximum exposure duration was 15 min, but participants were instructed to discontinue participation immediately if they experienced any symptoms of motion sickness, however mild. We analyzed movement kinematics not only in terms of sex and vehicle control but also in terms of participants who did or did not report motion sickness. Movement differed between Drivers and Passengers, in terms of both the spatial magnitude and multifractality of movement. The spatial magnitude of movement was simultaneously influenced by sex (men vs. women) and vehicle control (Drivers vs. Passengers). In addition, in statistically significant interactions, we identified postural precursors of motion sickness that differed between Drivers and Passengers and, separately, between Drivers and Passengers as a function of sex. The results are consistent with a prediction of the postural instability theory of motion sickness etiology and shed new light on the multifactorial origins of postural precursors of motion sickness in virtual environments.

Mechanical properties of blended cement mortar systems exposed to ammonium chloride environment

There are number of areas where cement composites can be exposed to ammonium based compounds such as agricultural land, chemical fertilizer plants, waste waters, polluted and industrial environments, which can induce severe and premature deterioration of concrete systems. Based on the review of literature, the most common and deleterious ammonium based salts were found to be ammonium nitrate, ammonium chloride and ammonium sulphate. The cementitious systems with Ordinary Portland Cement (OPC) may be attacked easily by these ammonium based chemicals as the OPC hydrates such as Portlandite and C-S-H gel are considered to be unstable in these aggressive media. Thus, it is necessary to understand the alteration kinetics of cementitious systems and the effectiveness of Supplementary Cementitious Materials (SCMs) in improving the resistance when exposed to ammonium based environments for develpoing more durable and sustainable concrete systems. The aim of this experimental study was to investigate the durability aspects in terms of the changes in mechanical properties of cement mortar specimens made with OPC and different combinations of various Supplementary Cementitious Materials (SCMs) exposed to ammonium based salt solution prepared using chemical grade ammonium chloride (NH4Cl). The mortar specimens were exposed to ammonium chloride solution in two different concentrations (1.25 M and 2.5 M) for a maximum exposure duration of two and half months. The SCMs used for the study include Class F Fly ash (FA), Ground Granulated Blast Furnace Slag (GGBS), and Silica fume (SF). The changes in the mechanical properties were evaluated on the basis of visual assessment, depth of penetration, changes in the compressive strength, changes in Ultrasonic Pulse Velocity (UPV) and relative dynamic modulus of elasticity. From all the test results, it can be concluded that the ternary blended mix with OPC, GGBS and Silica fume (OPC-GGBS-SF) has higher resistance to ammonium chloride attack. The results stress the need to include SCMs and the importance to tailor make the concrete for structures exposed to aggressive environment like ammonium chloride.

Evaluation of chemical and biological contaminants of emerging concern in treated wastewater intended for agricultural reuse

The occurrence of chemical and biological contaminants of emerging concern (CECs) was investigated in treated wastewater intended for reuse in agriculture. An agarose hydrogel diffusion-based passive sampler was exposed to the outlet of a wastewater treatment plant (WWTP) located in Cyprus, which is equipped with membrane bioreactor (MBR). Passive samplers in triplicate were exposed according to a time-series exposure plan with maximum exposure duration of 28 days. Composite flow-proportional wastewater samples were collected in parallel with the passive sampling exposure plan and were processed by solid phase extraction using HORIZON SPE-DEX 4790 and the same sorbent material (Oasis HLB) as in the passive sampler. The analysis of passive samplers and wastewater samples enabled (i) the field-scale calibration of the passive sampler prototype by the calculation of in situ sampling rates of target substances, and (ii) the investigation of in silico predicted transformation products of the four most ecotoxicologically hazardous antibiotics (azithromycin, clarithromycin, erythromycin, ofloxacin). Additionally, the wastewater samples were subjected to the analysis of seven preselected antibiotic resistant genes (ARGs) and one mobile resistant element (int1). All extracts were analyzed for chemicals in a single batch using a highly sensitive method for pharmaceuticals, antibiotics and illicit drugs by liquid chromatography tandem MS/MS (LC-QQQ) and for various other target compounds (2316 compounds in total) by liquid chromatography high-resolution mass spectrometry (LC-HRMS). 279 CECs and all investigated ARGs (except for blaCTX-M−32) were detected, highlighting potential chemical and biological hazards related to wastewater reuse practices. 16 CECs were prioritized following ecotoxicological risk assessment, whereas sul1 and the mobile resistant element (int1) showed the highest abundance. Comprehensive monitoring efforts using novel sampling methods such as passive sampling, wide-scope target screening and molecular analysis are required to assure safe application of wastewater reuse and avoid spread and crop uptake of potentially hazardous chemicals.

Association of intronic polymorphisms (rs1549339, rs13402242) and mRNA expression variations in PSMD1 gene in arsenic-exposed workers.

Ubiquitin-proteasome system (UPS) gene, PSMD1, is an important gene for neutralization of damaged and misfolded protein(s). The current study was designed to study the genetic and expression variations of PSMD1 gene as a consequence of arsenic exposure and its potential implications in arsenic induced diseases. In the present study, 250 blood samples of exposed industrial workers along with 250 controls were used. Initially, tetra amplification refractory mutation system-PCR was used to determine the role of PSMD1 gene polymorphisms (rs1549339, rs13402242) in industrial workers and controls. Frequency of homozygous mutant genotype of rs1549339 (OR: 2.23, 95% CI: 1.51-3.32, p = 0.0001) and rs13402242 (OR: 2.96, 95% CI: 1.52-5.75, p = 0.001) was observed significantly higher in exposed individuals vs controls. Secondly, qPCR was performed for expression analysis of PSMD1 gene. Significant down-regulated expression of PSMD1 gene (p < 0.0001) was observed vs controls, and this down-regulation was observed more pronounced in smokers (p < 0.0001) with maximum exposure duration (p < 0.0008). This down-regulated expression was observed significantly more pronounced in welding (p < 0.004) and brick kiln industries (p < 0.04) compared to other selected industries. The obtained results suggest that the exposure to arsenic may have an increased risk of developing disease(s) because of arsenic-induced PSMD1 variations.

Influence of W Content on the Oxidation Behaviour of Ternary $$\gamma ^{\prime }$$-Strengthened Co-Based Model Alloys Between 800 and $$900\,^{\circ }{\hbox {C}}$$

The oxidation behaviour of ternary Co–Al–W alloys with W contents between 7 and 10 at. $$\%$$ was investigated in detail. Continuous thermogravimetry was conducted between 800 and $$900\,^{\circ }{\hbox {C}}$$ to compare the impact of $$\gamma ^{\prime }$$ volume fraction on the overall mass gain during the comparably long transient stages of oxide-scale growth. Resulting cross-sections were assessed using electron microscope-based analysis methods. To understand prevailing oxidation mechanisms, the development and composition of multilayered oxide scales were the main focus of the present study. Elemental distribution of three individual scale sections was investigated with electron probe microanalysis. No striking impact of the W level in the alloy was found. However, the development of diffusion-limiting barrier layers was demonstrated to change with varying W contents. Continuous alumina layers were only observed after 100-h exposure at $$800\,^{\circ }{\hbox {C}}$$ . For samples with 9 at. $$\%$$ W, the grain structure within the outer Co-oxide layer was characterized with electron backscattered diffraction after the maximum duration of exposure. Individual growth kinetics for three distinguished layers within the oxide scales were used to compare elemental transport depending on the W content in the alloy and the exposure temperature.

Thermo-mechanical performance of Carbon Fiber Reinforced Polymer (CFRP), with and without fire protection material, under combined elevated temperature and mechanical loading conditions

In civil engineering, when a CFRP-reinforced structure is subjected to fire, both the structure and CFRP are simultaneously affected by elevated temperature and mechanical loading. In the Eurocodes, the strengths of concrete and steel are described to be reduced with increased temperature; however, the codes do not describe the performance of hand-laid CFRP. This paper presents the thermomechanical performance of hand-laid CFRP with and without thermal insulation under different mechanical loading conditions. Experimental tests were conducted to identify the maximum transient heating temperature and duration to which CFRP can be exposed at different levels of mechanical load. The results show that when the applied load increases, the rupture temperature and maximum exposure duration decrease. At 20 °C, the rupture temperature of CFRP gradually decreases when the applied load increases from 10% to 50% of the material's ultimate strength; at room temperature, as the applied load reaches 75% of the ultimate strength, the rupture temperature significantly decreases. Likewise, the exposure duration gradually decreases when the applied load varies from 10% to 50% of CFRP's ultimate strength, and decreases considerably when the applied load is 75% of the ultimate strength. Additional tests were conducted on CFRP protected by an insulation material to characterize the effectiveness of the used insulation material used on the performance of hand-laid CFRP subjected to thermal and mechanical loading. Finite element models were used to investigate the thermal conduction, and these models were successfully validated by the experimental results. Thus, the models were confirmed to predict the fire protection capability of the used insulation material reliably and accurately.

Laboratory Study of Topographic Effects on the Near-surface Tornado Flow Field

To study topographic effects on the near-surface tornado flow field, the Iowa State University tornado simulator was used to simulate a translating tornado passing over three different two-dimensional topographies: a ridge, an escarpment and a valley. The effect of the translation speed on maximum horizontal wind speeds is observed for translation speeds of 0.15 and 0.50 $$\hbox {m}\,\hbox {s}^{-1}$$ , with the lower value resulting in a larger maximum horizontal wind speed. The tornado translation over the three topographies with respect to flat terrain is assessed for changes in: (a) the maximum horizontal wind speeds in terms of the flow-amplification factor; (b) the maximum aerodynamic drag in terms of the tornado speed-up ratio; (c) the maximum duration of exposure at any location to high wind speeds of a specific range in terms of the exposure amplification factor. Results show that both the maximum wind amplification factor of 14%, as well as the maximum speed-up ratio of 14%, occur on the ridge. For all topographies, the increase in aerodynamic drag is observed to be maximized for low-rise buildings, which illustrates the importance of the vertical profiles of the horizontal wind speed near the ground. The maximum exposure amplification factors, estimated for the range of wind speeds corresponding to the EF2 (50–60 $$\hbox {m}\,\hbox {s}^{-1}$$ ) and EF3 (61–75 $$\hbox {m}\,\hbox {s}^{-1})$$ scales, are 86 and 110% for the ridge, 4 and 60% for the escarpment and − 6 and 47% for the valley, respectively.

Flibanserin for Hypoactive Sexual Desire Disorder: An Open-Label Safety Study

BackgroundTo evaluate the safety of flibanserin in premenopausal and naturally postmenopausal women with hypoactive sexual desire disorder (HSDD) in an open-label extension (OLE) study. AimTo examine the safety and tolerability of flibanserin 100 mg once daily at bedtime in the treatment of premenopausal and naturally postmenopausal women with HSDD in a multicenter 28-week OLE study. MethodsPatients entering this study received flibanserin or placebo in the double-blinded, placebo-controlled trials of premenopausal and postmenopausal women and in a pharmacokinetic study of postmenopausal women. OutcomesThe primary end point of this OLE study was the incidence of adverse events (AEs). Secondary exploratory efficacy measures included the Female Sexual Distress Scale–Revised (FSDS-R) total score and FSDS-R item 13 (distress owing to low desire) score and the Female Sexual Function Index (FSFI) total score. Because the sponsor terminated the study early at discontinuation of the development of flibanserin, only descriptive statistics were calculated. ResultsOf the 595 patients receiving study medication, 346 and 249 patients were premenopausal and postmenopausal, respectively. The mean number of days of exposure to flibanserin was 72.8 (SD = 41.6). AEs were reported by 352 patients (59.2%), and most AEs (93.8%) were mild or moderate. The most common AEs (≥5%) were dizziness (9.6%), somnolence (8.6%), insomnia (6.2%), and nausea (5.7%). There were no flibanserin-related serious AEs and no instances of suicidal ideation. The safety profile of flibanserin was similar for premenopausal and postmenopausal women. The FSDS-R total scores and FSDS-R item 13 scores were numerically lower at weeks 4, 12, and 20 than at baseline (decrease in distress owing to low desire) for premenopausal and postmenopausal women. Mean FSFI total scores were numerically higher at weeks 4, 12, and 20 than at baseline, irrespective of menopausal status of the patients. Clinical ImplicationsThe results of this study support the safety and tolerability of flibanserin for the treatment of HSDD in premenopausal and naturally postmenopausal women. Strengths and LimitationsAlthough this open-label study was designed to be 28 weeks long, it was discontinued early by the sponsor, and patients’ maximum duration of exposure to flibanserin was 23.9 weeks. The open-label design and lack of a placebo-controlled arm are other study limitations. ConclusionIn this open-label study, flibanserin 100 mg once daily at bedtime was generally safe and well tolerated by premenopausal and naturally postmenopausal women with HSDD.Simon JA, Derogatis L, Portman D, et al. Flibanserin for Hypoactive Sexual Desire Disorder: An Open-Label Safety Study. J Sex Med 2018;15:387–395.

Work Rotation to Reduce the Effect of Noise Exposure for Operators in Sugar Factory

This study investigates noise level at the grinding station in a sugar factory by measuring sound pressure level. This study aims to obtain noise level map, so that operators’ work hour can be regulated accordingly. Noise level is measured for four days using sound level meter. Observation is conducted at 9 points at 09.00, 11.00, 13.00, and 15.00 o’clock. The number of point of measurement is determined using contour mapping technique using grid size of 3m x 3m. Noise distribution pattern is obtained from surfer software v11.0. The results show that Daily Noise Dose (DND) exceeds the standard set by Occupational Safety and Health (OSHA). Every point of measurement has different noise level, which means that the maximum exposure duration allowed is also different. Maximum exposure duration allowed for the 9 points is ranging from 72.48 minutes to 143.54 minutes. This infers that the problem can be solved by work hour regulation of operators at each station; operators work for a different period of time at different stations.

Al-containing ODS steels with improved corrosion resistance to liquid lead–bismuth

The effectiveness of Al addition for improvement of the corrosion resistance of ODS steel in lead–bismuth eutectic (LBE) was investigated. Al-alloying surface treatment using a GESA facility was applied to 9Cr-ODS martensitic steel, and the corrosion resistance in stagnant LBE containing 10−6wt% oxygen was subsequently examined. Corrosion resistance of ODS ferritic steels with high Cr content (14.7wt%), containing 3.3–3.8wt% Al and small amounts of Zr or Hf, was also examined. Al-alloying surface treated 9Cr-ODS martensitic steel was tested at 650°C and ODS ferritic steels with high Cr content, containing 3.3–3.8wt% Al and small amounts of Zr or Hf, were tested at 650 and 700°C. The maximum exposure duration was 10,000h. All tested materials showed good corrosion resistance under all test conditions. Both the Al-alloying surface treatment by the GESA facility and the Al addition to the matrix with small amounts of Zr or Hf effectively improved the compatibility of ODS steel with LBE at high temperatures.

Thiazolidinediones and bone fractures.

Thiazolidinediones and bone fractures.

Corrosion resistance of Al-alloying high Cr–ODS steels in stagnant lead–bismuth

Corrosion resistances of oxide dispersion strengthened ferritic steels containing 3.5 wt% Al and 14–17 wt% Cr were examined. Experiments were performed in stagnant lead–bismuth eutectic (LBE) containing 10 −6 and 10 −8 wt% oxygen at 550 and 650 °C. The maximum exposure duration was 5000 h. Observations of the cross-sections of exposed samples obtained by scanning electron microscopy and Auger electron spectroscopy suggested that a very thin Al oxide layer was formed continuously. The materials containing 3.5 wt% Al exhibited good corrosion resistance despite being exposed to 5000 h of LBE containing 10 −6 wt% at 650 °C. Furthermore, a favourable influence of adding minor amount of Zr was detected after 5000 h exposure to LBE containing 10 −8 wt% oxygen at 650 °C.

A new safety parameter for diagnostic ultrasound thermal bioeffects: Safe use time

It is widely accepted that diagnostic ultrasound has the potential to elevate the temperature of tissue being scanned. Because both the maximum value of the temperature rise and the temporal profile of that rise are necessary to estimate the risk correctly, the temperature rise [DeltaT(t)] at an observation point for an exposure condition is presumed to have two components, that is, DeltaT(t)=DeltaT(max)X(t). The amplitude component DeltaT(max) is the maximum value of DeltaT(t), and the exposure time component X(t) represents the time dependency of that DeltaT(t). Ninety-six cases were investigated to obtain the proposed DeltaT(t) model at six frequencies, four source diameters, and four f-numbers. Then, using the relative change in the rate of induction of a thermal effect due to ultrasound exposure that produces DeltaT(t) different from a threshold exposure, the safe use time (SUT) model was constructed. SUT informs the user of the maximum duration of exposure in a region at a particular output level that would be no more hazardous than scanning at the threshold exposure. Using the SUT model, high power ultrasound can be applied for a short time so that the user can improve imaging performance while staying within safe limits.

Could sound be used as a strategy for reducing symptoms of perceived motion sickness?

BackgroundWorking while exposed to motions, physically and psychologically affects a person. Traditionally, motion sickness symptom reduction has implied use of medication, which can lead to detrimental effects on performance. Non-pharmaceutical strategies, in turn, often require cognitive and perceptual attention. Hence, for people working in high demand environments where it is impossible to reallocate focus of attention, other strategies are called upon. The aim of the study was to investigate possible impact of a mitigation strategy on perceived motion sickness and psychophysiological responses, based on an artificial sound horizon compared with a non-positioned sound source.MethodsTwenty-three healthy subjects were seated on a motion platform in an artificial sound horizon or in non-positioned sound, in random order with one week interval between the trials. Perceived motion sickness (Mal), maximum duration of exposure (ST), skin conductance, blood volume pulse, temperature, respiration rate, eye movements and heart rate were measured continuously throughout the trials.ResultsMal scores increased over time in both sound conditions, but the artificial sound horizon, applied as a mitigation strategy for perceived motion sickness, showed no significant effect on Mal scores or ST. The number of fixations increased with time in the non-positioned sound condition. Moreover, fixation time was longer in the non-positioned sound condition compared with sound horizon, indicating that the subjects used more time to fixate and, hence, assumingly made fewer saccades.ConclusionA subliminally presented artificial sound horizon did not significantly affect perceived motion sickness, psychophysiological variables or the time the subjects endured the motion sickness triggering stimuli. The number of fixations and fixation times increased over time in the non-positioned sound condition.

Toxicity of Australian essential oil Backhousia citriodora (lemon myrtle). Part 2. Absorption and histopathology following application to human skin

The in vitro percutaneous absorption of the essential oil of lemon myrtle ( Backhousia citriodora) has been studied in freshly excised human full-thickness abdominal skin obtained from patients undergoing elective surgery. Absorption of lemon myrtle oil in human skin discs (4.9 cm 2) was evaluated using a Franz cell diffusion system following topical application of neat lemon myrtle oil (100 μl or 18.29 mg/cm 2) to the epidermal surface at exposure durations of 1 to 12 h. Gas chromatography mass spectrometry (GCMS) was used as an analytical technique to determine the absorption of lemon myrtle oil components in full-thickness skin. Citral; (consisting of isomers, geranial and neral) was the only component of lemon myrtle oil found to be absorbing into skin at all exposure periods. At the maximum exposure duration of 12 h, the total absorption of citral in the full-thickness skin disc was 0.29±0.07 mg/cm 2 (mean±S.D., n=4) of the applied dose. Although the absorption of lemon myrtle oil components was limited, haematoxylin and eosin (H&E) staining showed significant losses in the cellular functioning of skin including; losses of integrity and solubilisation of the stratum corneum, cellular necrosis (to 15%) and cellular vacuolation (to 25%) on comparison to control skin. When a formulated product containing 1% lemon myrtle oil (0.18 mg/cm 2) was applied to human skin discs (4.9 cm 2) at 8 h exposure the total absorption of citral in the full-thickness skin disc was 5.12±0.60×10 −4 mg/cm 2 (mean±S.D., n=4) of the applied dose. No other components were detected. The histopathological assessment indicated limited damage to epidermal cells. The combination of the above methodologies enabled the generation of data that could be used for a comprehensive evaluation of the toxicity effects of lemon myrtle oil for topical application.

Assessment of the Risks of Heat Disorders Encountered during Work in Hot Conditions

Eight laboratories participated in a concerted research project on the assessment of hot working conditions. The objectives were to: Co-ordinate the work of the main European research teams in the field of thermal factors Improve the methods available to assess the risks of heat disorders at the workplace, and in particular the ISO standard 7933. Better define the criteria for the maximum exposure duration, considering interindividual differences in sweating rate, water loss and core temperature increase. Design and validate an assessment strategy for practitioners to determine maximum exposure durations and optimise the working environment. The revised model, called “Predicted Heat Strain” proved to predict much better than the previous Required Sweat Rate model the maximum allowable exposure duration to avoid dehydration and/or core temperature increase.