Exposition Time Research Articles

On Some Aspects of Radiation Protection for High-School Level Students

In this short note we discuss some principles of radiation protection at a high-school level. In this attempt, a set of graphics were designed based on the evaluation of an empirical expression, which depends on the distance from the source of radiation, time of exposition to the source and the attenuation of the radiation by a barrier.

On the use of stochastic simulations to explore the impact of human parameters on mass public shooting attacks

A variety of individuals are likely to be involved in mass shooting attacks. However, the potential effect of people characteristics and response in such situations remains unclear. To address this issue, here we use a new stochastic model to identify patterns that maximize the survival probability and minimize the effectiveness of the shooter. As expected, while survival rates increase when people move fast (since they become a more difficult target to hit and their exposition time is reduced), chances of surviving decrease with non-escaping behaviours. We also found that densely occupied enclosures result in more casualties than sparsely occupied ones, however, casualties at high densities represent a smaller proportion of the individuals involved. Interestingly, even though the shooter effectiveness increases as the crowd becomes denser, so does too the survival probability overall. These findings challenge our current understanding of the impact of human parameters on mass shooting attacks.

Robotic-assisted dynamic large drop microextraction

By proper design of an innovative extraction device, a lab-made multipurpose autosampler was exploited in the automated performance of the dynamic large drops based microextraction. The pluses of this new analytical strategy were demonstrated in the determination of sulfonamides and fluoroquinolones in surface water samples, by direct immersion single drop microextraction (SDME) and liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS) analysis. Operational autosampler features and critical experimental factors influencing SDME, including the extraction mode (static or dynamic), extraction, stirring rate, salt addition, drop size, number of cycles and drop exposition time, were comprehensively investigated using both univariate and multivariate optimization. The lab-made autosampler allowed to performance challenging dynamic and static large drop based SDMEs in an automated and effortless way and with minimal requirements of hardware and software. Large stable drops provided high surface area, enhancing the phase ratio and in consequence increasing the analytes uptake. The best extraction efficiencies were obtained as a result of the synergic interaction between the use of large drops and the automated dynamic mode of extraction. The developed method proved to be a reliable, sensitive, and robust analytical tool, with intraday RSDs ranging between 4.0 and 7.6% (n = 6), and interday RSDs between 4.8 and 9.3% (n = 6), and, LOD and LOQ in the range of 15–50 and 35–100 ng L−1, respectively.

Nylon-Supported Plasmonic Assay Based on the Aggregation of Silver Nanoparticles: In Situ Determination of Hydrogen Sulfide-like Compounds in Breath Samples as a Proof of Concept.

A procedure for supporting silver nanoparticles (AgNPs) on nylon is proposed. Besides, the membrane has been developed as a solid-phase colorimetric plasmonic sensor for volatile sulfide compounds (VSCs) like H2S, CH3SH, and (CH3)2S. AgNP behavior in the membrane has been studied by UV-vis diffuse reflectance spectrometry, Raman spectrometry, High-resolution transmission electron microscopy (HR-TEM), and Scanning electron microscopy (SEM). The sensor responded by changing its color from yellow in absence of VSCs to several orange/brown colors in the function of VSC concentration as occurs in solution; an increase in the hydrodynamic diameter, estimated by both asymmetrical flow field-flow fractionation (AF4) coupled on line to Dynamic light scattering (DLS) detector and batch DLS, is achieved when sulfide is added to the citrate-capped AgNPs. Diffuse reflectance spectrometry and processed digital images obtained with a smartphone have been used as measurements and several transformations for quantitation are proposed; a linear concentration range of hydrogen sulfide from 150 to 1000 ppbv and a detection limit (LOD) of 45 ppbv were achieved, measuring after 10 min of the sensor exposition to the hydrogen sulfide atmosphere (2 L) for humidity percentages between 50 and 96% and room temperature. Satisfactory results in terms of precision (<10%) and selectivity were obtained. The new sensor reported was stable, sensitive, inexpensive, disposable, safe, and user-friendly. Furthermore, it has successfully been applied to determine VSCs expressed as hydrogen sulfide in breath samples (2 L and 250 mL) as a proof of concept. The limit of detection can be improved by increasing the exposition time, if necessary.

Sex Dimorphic Responses of the Hypothalamus-Pituitary-Thyroid Axis to Maternal Separation and Palatable Diet.

Neonatal stress contributes to the development of obesity and has long-lasting effects on elements of the hypothalamus–pituitary–thyroid (HPT) axis. Given the importance of thyroid hormones in metabolic regulation, we studied the effects of maternal separation and a high-fat/high-carbohydrate diet (HFC), offered from puberty or adulthood, on HPT axis activity of adult male and female Wistar rats. Pups were non-handled (NH) or maternally separated (MS) 3 h/day at postnatal days (Pd) 2–21. In a first experiment, at Pd60, rats had access to chow or an HFC diet (cookies, peanuts, chow) for 1 month. Male and female NH and MS rats that consumed the HFC diet increased their caloric intake, body weight, and serum insulin levels; fat weight increased in all groups except in MS males, and serum leptin concentration increased only in females. Mediobasal hypothalamus (MBH) Pomc expression increased in NH-HFC females and Npy decreased in NH-HFC males. MS males showed insulinemia and hypercortisolemia that was attenuated by the HFC diet. The HPT axis activity response to an HFC diet was sex-specific; expression of MBH thyrotropin-releasing hormone-degrading ectoenzyme (Trhde) increased in NH and MS males; serum TSH concentration decreased in NH males, and T4 increased in NH females. In a second experiment, rats were fed chow or an HFC diet from Pd30 or 60 until Pd160 and exposed to 1 h restraint before sacrifice. Regardless of neonatal stress, age of diet exposition, or sex, the HFC diet increased body and fat weight and serum leptin concentration; it induced insulinemia in males, but in females only in Pd30 rats. The HFC diet's capacity to curtail the hypothalamus–pituitary–adrenal axis response to restraint was impaired in MS males. In restrained rats, expression of Trh in the paraventricular nucleus of the hypothalamus, Dio2 and Trhde in MBH, and serum thyroid hormone concentration were altered differently depending on sex, age of diet exposition, and neonatal stress. In conclusion, metabolic alterations associated to an HFC-diet-induced obesity are affected by sex or time of exposition, while various parameters of the HPT axis activity are additionally altered by MS, pointing to the complex interplay that these developmental influences exert on HPT axis activity in adult rats.

Kinetics of Dispersion During Annealing in Vacuum of Thin Double Nickel-Silver Films Deposited onto Oxide Materials

The kinetics of dispersion of thin nickel-silver films deposited onto alumina and zirconia ceramics and annealed in vacuum at temperatures up to 1000 °C with different exposition times at each temperature (from 5 up to 20 min) was studied. The double films consisted of two layers: the first metallization layer was 150 nm nickel nanofilm deposited onto the oxide surface, and the second silver layer 1.5 mm thick deposited over the first one as a solder was used for joining of metallized oxide samples. It was found that these films remain rather dense during short-term heating up to 900 °C; and, after annealing at 950 °C and 1000 °C, they decompose immediately into individual droplets covering more than half the area of the ceramic substrates. The kinetic curves for the dispersion of these films were plotted.

Effect of Plasma Surface Treatment on the Impact Behavior of Basalt/Epoxy Composites

In this study, the effects of surface treatment of a low-temperature atmospheric oxygen plasma on basalt/epoxy composites were investigated to improve the hydrophobility of the composite surface. After the plasma treatment, the unmodified and surface treated composite laminates have been experimentally characterized by performing contact angle measurements, low-velocity impact tests and indentation depth on the impacted laminates. Results have showed a dependence of such composite properties on the plasma coating deposition and on the treatment parameters outlining the need to optimize both the plasma power and exposition time to plasma in order to assess the efficiency of the plasma treatment and establish the optimal processing conditions.

The influence of thermal comfort conditions on user's exposure time in open spaces.

This paper discusses the influence of the user thermal comfort conditions on the time spent in open spaces through a case study performed in Bauru, Sao Paulo, Brazil. The study was carried out in two subspaces of a zoo, under warm and wet conditions. Although the subspaces had different levels of shading, they were of similar interest to visitors. The methodology adopted the collection of objective (air and globe temperature, humidity, and velocity) and subjective data (by application of questionnaires), for a sample of 174 users, and local observations with photographic records each 3min. Data and images obtained enabled the characterization of the local microclimates and contributed to evaluate (1) user's thermal perception (7-point scale), (2) affective evaluation of the thermal comfort (4-point scale), (3) thermal preference (7-point scale), (4) calculated thermal perception (through PET (physiological equivalent temperature) index), and (5) user's exposure time in each subspace. The great contributions of this work were to identify that in the subspace with bigger shading and less rigorous microclimatic conditions, users had exposure time longer than another more exposed to solar radiation and to validate a method to measure user's exposition time through sequential photos. These results contribute to a discussion that has yet been little explored in the literature of the area, proving the strong influence of the thermal comfort conditions in the users' exposure time in open spaces.

Drug survival of conventional systemic and biologic therapies for moderate-to-severe psoriasis in clinical practice in Spain: prospective results from the SAHARA study

Background: A better understanding of determinants for drug survival of antipsoriatic agents may guide dermatologists in the right therapeutic choice.Objectives: To describe 2-year drug survival of conventional and biologic antipsoriatic treatments.Methods: SAHARA was a prospective study in patients with moderate-to-severe psoriasis who initiated a conventional or biologic drug. Kaplan-Meier analysis estimated the drug survival and Cox regression the predictors of treatment persistence at two years.Results: A total of 552 patients were included (conventional group n = 181, biologic group n = 371). After a median treatment duration of 21.4 months, more than 50% of patients remained on methotrexate, etanercept, and ustekinumab whereas the median exposition time to cyclosporine, acitretin, and adalimumab was 11.8, 10.6, and 25.5 months, respectively. There were 178 discontinuations for all causes, mainly in patients who initiated cyclosporine (58.3%), acitretin (52.8%), and adalimumab (46%), and less frequently with ustekinumab (14%). The main reason for discontinuing biologics was lack of efficacy (70%), especially for etanercept (76%).Conclusion: Biologics have a superior drug survival rate than conventional therapies. Ustekinumab is the biologic with the longest drug survival, only affected by the gradual loss of efficacy assumed for biological therapies.

Cracking resistance evaluation of asphalt binders subjected to different laboratory and field aging conditions

The ability of the Pressure Aging Vessel (PAV) to properly simulate the long-term aging characteristics of asphalt binders has been questioned by researchers in the recent years. Several research efforts have indicated that the current PAV protocol may age the materials significantly less severely than the actual environmental field agents. Alternatively, updates on the current PAV testing procedures have been proposed to age the binders for 20 or even 60 h beyond the current 20 h. A protocol with very thin binder films, named as Universal Aging Test, has also been recommended by the Western Research Institute. Thermal aging with the combination of ultraviolet radiation exposition and heating has also been regarded as a possible more realistic route. This work aims to evaluate the cracking characteristics of nine unmodified and three modified (by SBS, ground tire rubber, and TLA) asphalt binders aged by different testing methodologies, i.e. a thermal route with changing exposition times and an ultraviolet route. The carbonyl index and the benzylic hydrogen content obtained by Fourier Transform Infrared Spectroscopy and Nuclear Magnetic Resonance, respectively, were evaluated to identify the chemical effects of the different aging strategies. The cracking resistance of the aged binders was evaluated by means of the Glover–Rowe (GR) parameter and of LAS test results. The GR results showed that the critical block-cracking zone could be reached by the two routes, being the oxidative effect that happens in the field more evident in the UV radiation route. Larger values of the benzylic hydrogen were observed for the materials deriving from a deasphalting residue process, resulting in higher susceptibility to aging. The carbonyl index was very sensitive to UV aging and presented in general larger values than the other aging strategies. The presence of an elastomeric modifier apparently protected the SBS and GTR samples against UV aging.

Happy hours: could chips and nuts be vector of food-borne outbreaks?

BACKGROUND The global interest in handling food has increased over the years. Greater handling raises the risk of contamination, also in the backed food. The aim of this study is to understand the type and level of microbial contamination in the food that is served along happy hour in the bars/coffee. METHODS This pilot study was performed from April to May 2018 in a city of central Italy ( RESULTS A significant yeasts contamination appeared only on potatoes at T0 (p CONCLUSIONS We showed an increase in the microbial load associated with food handling, mostly of Enterococci. Long time of exposition increased the likelihood of contamination and the possibility to exceed the dose for the occurrence of disease. Offering small portions of handling food would reduce the manipulation by participants and the risk of food-borne outbreaks.

Impact of certain nano oils against Ephestia kuehniella and Ephestia cutella (Lepidoptera-Pyralidae) under laboratory and store conditions

BackgroundFor the purpose of environmental safety, many essential oils were recommended in many Integrated Pest Management (IPM) programs to protect plants from insect’s infestations and have few effects on non-target organisms and the environment. This study was aimed to investigate and estimate the activity of four nano essential oils against tested insects under laboratory and store conditions.MethodsThe nano encapsulation process was carried out by polymerization technology. The tested nano oils were experimented at tested concentration (0.5%) for their insecticidal activities against the third-instar larvae of tested insects. After 7 days of exposure, accumulative mortality percentages were calculated in the treated and untreated control. Also, the tested nano oils were sprayed to the foam granules and were mixed with wheat (2 g foam/100 g wheat) for testing the oviposition inhibitory effects of tested oils. Additionally, the experiment was designed to test the persistent effect of tested oils against Ephestia kuehniella and E. cautella on foam as surface protectant after 90-day intervals.ResultsThe larval accumulative mortality of tested insect species enhanced progressively with the increase of exposition times (7 days). In the case of tested insects, rosemary oil gave the highest accumulative mortality percentages. The persistence effects of tested nano oils on foam and covering gunny bags showed various biological activates by reducing number of eggs, almost suppressing the percentages of progeny emergence (F1) and high percentages of malformation of tested insects. The efficacy of the tested nano oils on the weight loss of wheat grains after 90 days of storage was experimented.ConclusionResults of this work and that of other researchers indicate that some essential oils might be useful for managing insects in enclosed spaces because of their fumigant action. Plant essential oils and their active ingredient have potentially high bioactivity against a range of insects. Furthermore, they are highly selective to insects. Incorporation of essential oils into a controlled release nanoformulation prevents rapid vaporization and degradation, increases constancy, and preserves the lower effective dosage/application. Treated foam with nano rosemary and nano eucalyptus oil and covering gunny bags provided many efficient effects against tested insects.

Mite Communities (Acari, Mesostigmata) in the Initially Decomposed ‘Litter Islands’ of 11 Tree Species in Scots Pine (Pinus sylvestris L.) Forest

Replacement of native deciduous forests by coniferous stands was a common result of former European afforestation policies and paradigms of forest management and led to considerable ecological consequences. Therefore, the most popular management strategy nowadays in multi-functional forestry is the re-establishment of mixed or broadleaved forests with native species on suitable habitats. However, our knowledge about the effects of tree species introduced into coniferous monocultures on soil mesofauna communities is scarce. We investigated abundance, species richness and diversity of Mesostigmata mite communities in decomposed litter of seven broadleaved (Acer platanoides L., A. pseudoplatanus L., Carpinus betulus L., Fagus sylvatica L., Tilia cordata Mill., Quercus robur L., Q. rubra L.) and four coniferous (Abies alba Mill., Larix decidua Mill., Picea abies [L.] Karst., Pinus sylvestris L.) species. We collected 297 litterbags after 6, 12 and 18 months of exposition in Scots pine (Pinus sylvestris) monocultures in Siemianice Experimental Forest (SW Poland). Generally, species richness and diversity in litter samples were much lower than in the soil mite pool. The highest abundance was found in P. sylvestris and A. alba litter, while the lowest was found in A. platanoides. The most abundant families were Zerconidae, Parasitidae, Veigaiidae, and Trachytidae. Our study revealed that neither species richness nor diversity were affected, but that mite abundance was affected, by the tree species (litter quality). The mite communities were similarly comprised in both high- and low-quality litter and mite abundance decreased during the decomposition process in nutrient-poor Scots pine forests. Moreover, few mite species benefited from the decomposed litter. Additionally, a litter of various tree species was inhabited mainly by eu- and hemiedaphic mite species. Mite assemblages in A. alba, P. sylvestris, and Q. robur litter had higher abundances. Exposition time seems to be an important driver in shaping the mite community during the early stages of litter decomposition.

Ultrasonic phase velocity of carbonated cement paste probes

The carbonation process in concrete is due to the interaction of the cement paste with atmospheric carbon dioxide modifying the cementitious matrix microstructure and its elastic properties, affecting its durability as a result of formed microcracks and chips within the concrete structure. The effects of this chemical reaction can be monitored using ultrasonic non destructive technique based on the scattering of the incident pulse. Acoustic phase velocity analysis was carried out on acquired signals coming from cement paste specimens of different water-cement ratios, during controlled carbonation process. The results show that the acoustic dispersion increases as a function of CO2 exposition time, where the microstructure of 0.6 water-cement ratio probes react faster to the carbonation. These results are in accordance with the experimental carbonation index, obtained by the well known Fourier Transform Infrared Spectroscopy technique.

Friction of dental resin composite exposed to lactic acid

Introduction: Lactic acid concentration in the blood and saliva increases during physical exercise [1], leading to dental erosion and the degradation of restorative dental materials [2]. Our goal is to evaluate the effect of lactic acid exposure on the surface of a composite resin Materials and methods: 16 discs were made from Filtek ™ Z250. Every disc was divided into three distinct areas, resulting in a total of 48 samples that were randomly distributed into four groups (n = 12). Group A and B were placed in 5 mL of artificial saliva while group C and D were placed in 5 mL of lactic acid (pH =4.0). Intermittent exposure to the acidic solution (8 hours) alternated with artificial saliva (8 hours), till complete 1 day (group C) or 7 days (group D). All samples were submitted to nanotribological wear tests with a Nano-Tribometer (CSM Instruments SA, Peseux, Switzerland), using as counter-body a zirconia ball. Statistical analysis via one-way ANOVA with Tukey HSD Post Hoc test and independent samples t-tests were performed. Results: The highest friction coefficient (Table 1) was obtained with the acid lactic group at both timings (0.188 at 1 day and 0.144 at 7 days). Statistically significant differences between solutions were found with time: friction coefficient decreased in all groups when the exposition time increases from 1 to 7 days. (p < 0.05). Discussion and conclusions: The resin exposed in an intermittent way to lactic acid for 1 day presented the highest friction coefficient. The obtained results showed that lactic acid led to an increase of the friction coefficient, which was more significant for the lower exposure time. This may be attributed to the acid effect on the surface of the resin that wears the resin making it smoother, thus reducing friction.

PAHs, pesticides, personal care products and plastic additives in plastic debris from Spanish Mediterranean beaches

In this study the role of plastic debris as a pollution vector has been evaluated by determining the concentrations of hydrophobic organic contaminants in polymers from three Western Mediterranean coastal areas as well as their potential transfer to seawater. Plastic debris was sampled at three Iberian Peninsula Southeastern beaches, each affected by different predominant anthropogenic activities (tourism, agriculture, urban activities, transport and industry). Plastic debris was characterized by attenuated total reflection Fourier-transform infrared spectrometry. The organic contaminants were extracted from plastics by ultrasonic extraction with methanol and quantified by stir bar sorptive extraction coupled to gas chromatography–mass spectrometry (GC–MS). In two areas, the desorption of these contaminants from plastic debris to seawater during 24 h was also evaluated. The contaminant groups considered in this study (polycyclic aromatic hydrocarbons (PAHs), personal care products (PCPs), current use pesticides (CUPs), organochlorinated compounds (OCPs, including polychlorinated biphenyls and organochlorinated pesticides) and plastic additives were found in polymers from the three areas. The most abundant contaminants were plastic additives and PCPs, underlining the relevance of the leaching of plastic components, and urban and tourism activities as typical pollution sources in the coastal areas. In general, large piece-to-piece variability was found for all polymers and areas mainly as a consequence of their different origin, exposition time, use and surface-to-volume ratio. This fact difficulted the visualization of significant differences between polymers or areas, but for CUPs, whose concentrations were significantly higher in Cape Cope than in the other areas due to the influence of close agricultural activities. PCPs and CUPs were desorbed partially in seawater for 24 h, particularly the most hydrophilic compounds such as triazines and other CUPs. However, a significant fraction of other contaminants (mainly PAHs) was retained, which suggests they can be transported far away from their origin.

Hemipenes eversion behavior: a new form of communication in two Liolaemus lizards (Iguania: Liolaemidae)

Males of several animals have intromittent organs and may use these in a communicative context during sexual or intrasexual interactions. In some lizards, hemipenes eversion behavior have been observed, and the aim of this study is to find out whether this behavior is functionally significant under a communicative approach. Here, we investigated the eversion of hemipenes in the Light Blue Lizard (Liolaemus coeruleus Cei and Ortiz-Zapata, 1983) and in the Valley Lizard (Liolaemus quilmes Etheridge, 1993) by filming the response of male focal lizards in different experimental settings: (i) an agonistic context, i.e., with a conspecific male, (ii) a sexual context, i.e., with a conspecific female, and (iii) a control treatment, i.e., without a treatment lizard. In both species, focal lizards showed this behavior only in an agonistic context, with interspecific differences as follows. Liolaemus coeruleus has longer times until eversion and dragging of hemipenes; however, it has shorter time of eversion and exposition of the hemipenes. Liolaemus quilmes has the opposite pattern compared with L. coeruleus. These indicate that eversion of the hemipenes can act as a visual display and as a signal of aggressive behavior towards conspecific rival males. The present study offers a new behavioral perspective on the use of masculine genitalia in lizards.

The Influence of Low-Frequency Vibrations on the Lipid Profile in Women

Introduction: The aim of this dissertation is an evaluation of the effect of low frequency vibration on serum lipid profiling women. Materials and Methods: A group of females aged 28-64 years old were assessed twice, before and after 19 days of exposure to low frequency vibration. The parameters of the vibration used (frequency and amplitude) and the short exposition time were selected in order to comply with standards established to safeguard human health; mechanical stimulus safe for human health according to the Polish Standard PN EN ISO 2631-1:1997. The parameters used were as follows: frequency 3.5Hz, amplitude 4 mm and duration time 20 min. The main exclusion criteria for this study were: neoplasm, history of myocardial infarction, history of stroke, history of bone fracture within the two years prior to the study. To assess the effect of low frequency vibration with the parameters as specified above the following physiological and biochemical variables were used: total cholesterol serum level, high density lipoprotein (HDL) cholesterol serum level, low density lipoprotein (LDL) cholesterol serum level, triglycerides (TGD) serum level. Biochemical blood parameters were assessed before and after the trial. Friedawald’s formula was used for the assessment of LDL cholesterol serum level. Upon completion of the study and the subsequent analysis of the results obtained the following conclusions were formulated. Results: A statistically significant lowering of total serum cholesterol and LDL serum cholesterol was observed. Conclusions: The use of the vibration platform with the operational parameters specified had a beneficial effect on the variables measured.

ESEM-EDS-based analytical approach to assess nanoparticles for food safety and environmental control

Particulate contamination in the form of nanoparticles (NPs) can occur not only in the environment but also in the food production chain, making human exposure almost inevitable. In the present study the potentialities of Environmental Scanning Electron Microscopy coupled with Energy-Dispersive X-ray Spectroscopy (ESEM-EDS) were exploited for the detection and visualization of inorganic NPs in air, raw materials and food products along the pasta production chain (wheat ear, wheat, semolina and pasta). Investigation of the elemental composition of NPs in the same samples was also carried out by using two independent techniques: ESEM-EDS and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). As for airborne particles, size-fractionated sampling was performed by an eight-stage cascade impactor located near the production plant with different exposition times for both ESEM-EDS and gravimetric analysis, respectively. In the case of raw materials and food products, the particles were collected on polycarbonate filters after immersion in milli-Q water in order to recover the NPs deriving from external environmental contamination. Only particle sizes lower than 0.8 µm were taken into consideration when ESEM-EDS analysis was carried out. NPs containing mainly Fe and Ti having dimensions <0.15 µm were identified in the filters used for wheat ear, wheat, semolina and pasta samples. As for air monitoring, gravimetric analysis showed an increase in the concentration levels of total particles during winter, particularly in the case of fine particulate matter (PM2.5). ESEM-EDS analysis, performed on filters of the VII and final stages, evidenced the same trend observed by gravimetric analysis, the majority of Fe-containing NPs being detected.

UV irradiation effect on the electrical properties of Pb2MoO5 single crystal

Electrical properties of Pb2MoO5 single crystal were studied in AC field (f=1 kHz) after irradiation with UV light (290 K). It was found that UV irradiation caused appearance of maximums on permittivity ε and conductivity σ temperature dependences, which were observed around 530 K. The anomalies of ε and σ vanished after annealing at 700 K and could be restored by subsequent UV irradiation performed at room temperature. The magnitude of ε and σ peaks increased for higher exposition time. Above 600 K conductivity σ was practically independent on irradiation. It is proposed that photoelectrons induced by UV light, are trapped by Mo located -within the oxygen tetrahedrons with vacancy VO in one of the vertexes. The dipole moments of (MoO3) groups reorient at VO hopping through the tetrahedron vertexes. Annealing at 700 K thermally decomposes (MoO3)- complexes. For T&gt;600 K behavior of σ(T) is determined by conduction currents and nearly insensitive to UV irradiation. At high temperatures the photoelectrons do not contribute to conductivity since they are bound in (MoO3)- centers, recombine with holes or re-captured by more deep traps.