1,720,981 research outputs found
Temporal variation of VOC emission from solvent and water based wood stains
No full textSolvent- and water-based wood stains were monitored using a small test emission chamber in order to characterize their emission profiles in terms of Total and individual VOCs. The study of concentration-time profiles of individual VOCs enabled to identify the compounds emitted at higher concentration for each type of stain, to examine their decay curve and finally to estimate the concentration in a reference room. The solvent-based wood stain was characterized by the highest Total VOCs emission level (5.7mg/m3) that decreased over time more slowly than those related to water-based ones. The same finding was observed for the main detected compounds: Benzene, Toluene, Ethylbenzene, Xylenes, Styrene, alpha-Pinene and Camphene. On the other hand, the highest level of Limonene was emitted by a water-based wood stain. However, the concentration-time profile showed that water-based product was characterized by a remarkable reduction of the time of maximum and minimum emission: Limonene concentration reached the minimum concentration in about half the time compared to the solvent-based product. According to AgBB evaluation scheme, only one of the investigated water-based wood stains can be classified as a low-emitting product whose use may not determine any potential adverse effect on human health
Gas Chromatography analysis with olfactometric detection (GC-O): an innovative approach for chemical characterization of odor active Volatile Organic Compounds (VOCs) emitted from a consumer product
No full textThe gas chromatography-olfactometry (GC-O) methodology couples traditional gas chromatographic analysis with sensory detection in order to identify odor active compounds in complex mixtures. Volatile Organic Compounds (VOCs) emitted from materials and consumer products can affect indoor air quality (IAQ) in terms of odor annoyance and other adverse effects on human health. Hence, the main purpose of the present paper was to recognize the odor active VOCs emitted by a specific consumer product and responsible of the odor annoyance perceived, performing head-space experiments followed by GC/MS-O analysis both at ambient temperature and during heating (condition of use). Ten odor active VOCs belonging to different chemical classes were detected; Aromatic Hydrocarbons (Benzene, Toluene, m/p-Xilene), Phenols (Phenol), Aldehydes (Benzaldehyde, Nonanale), Chlorinated Aromatic Hydrocarbons (Chlorobenzene, 1,4-Dichlorobenzene), Polycyclic Aromatic Hydrocarbons (Naphtalene) and Anhydrides (Phtalic Anhydride). Naphthalene was recognized as the organic compound that mainly contributed to the overall odor perceived. Moreover, it was observed that the product’s heating resulted in an increasing of VOCs emission and in odor perception. Experimental data obtained highlighted the potentialities of GC/MS-O methodological approach to identify off-flavors deriving from materials and to provide useful indications to manufacturers to improve the acceptability of odorous emissions
Chemical characterization of ODOR active volatile organic compounds emitted from perfumes by GC/MS-O
No full textThe selection of proper compounds to include in perfumesâ formulation is of particular interest for the perfume industry. Essential oils and perfumes are subject to quality control as well as to chemical characterization; therefore, GC/MS-O methodology can be considered a useful tool for research purposes and/or for improving industrial manufacturing processes. In this study, GC/MS-O methodology was applied to a commercial brand perfume and a natural-derived one, both characterized by a floral scent, with the main purpose of recognizing the odor active VOCs responsible of the characteristic and predominant notes. GC/MS-O analysis highlighted that sensory detection can be more efficient than the analytical one. Ocimene, α-Ionone and α-Isomethylionone were the most abundant odor compounds for the commercial-brand perfume, while Î2-Hydroxyethylbenzene was detected for the natural-derived one. Moreover, organic compounds of concern such as Toluene and Benzyl Alcohol were detected highlighting the need for quality control to reduce human risks for inhalation exposure and allergies
Breath Analysis: A Systematic Review of Volatile Organic Compounds (VOCs) in Diagnostic and Therapeutic Management of Pleural Mesothelioma
Full text linkMalignant pleural mesothelioma (MPM) is a rare neoplasm related to asbestos exposure and with high mortality rate. The management of patients with MPM is complex and controversial, particularly with regard to early diagnosis. In the last few years, breath analysis has been greatly implemented with this aim. In this review the strengths of breath analysis and preliminary results in searching breath biomarkers of MPM are highlighted and discussed, respectively. Through a systematic electronic literature search, collecting papers published from 2000 until December 2018, fifteen relevant scientific papers were selected. All papers considered were prospective, comparative, observational case-control studies although every single one pilot and based on a relatively small number of samples. The identification of diagnostic VOCs pattern, through breath sample characterization and the statistical data treatment, allows to obtain a strategic information for clinical diagnostics. To date the collected data provide just preliminary information and, despite the promising results and diagnostic accuracy, conclusions cannot be generalized due to the limited number of individuals included in each cohort study. Furthermore none of studies was externally validated, although validation process is a necessary step towards clinical implementation. Breathomics-based biomarker approach should be further explored to confirm and validate preliminary findings and to evaluate its potential role in monitoring the therapeutic response
Liquid chromatography with tandem mass spectrometry method for the determination of nicotine and minor tobacco alkaloids in electronic cigarette refill liquids and second-hand generated aerosol
No full textA liquid chromatography with tandem mass spectrometry method for the simultaneous quantification of nicotine and seven minor tobacco alkaloids in both refill liquids for electronic cigarettes and their generated aerosol was developed and validated. The limit of detection and limit of quantification values were 0.3–20.0 and 1.0–31.8 ng/mL, respectively. Within-laboratory reproducibility was 8.2–14.2% at limit of quantification values and 4.8–12.7% at other concentration levels. Interday recovery was 75.8–116.4%. The method was applied to evaluate the compliance of commercial liquids (n = 95) with their labels and to assess levels of minor alkaloids. Levels of nicotine and its corresponding compounds were also evaluated in generated aerosol. About 47% of samples showed differences above ±10 % of the stated nicotine concentration. About 78% of the “zero nicotine” liquids showed traces in the range of 1.3 ± 0.1–254.0 ± 14.6 μg/mL. Nicotine-N′-oxides, myosmine, and anatabine were the most common minor alkaloids in liquids containing nicotine. Nicotine and N′-oxides were detected in all air samples when aerosol was generated from liquids containing nicotine. Nicotine average emissions from electronic cigarette (2.7 ± 0.9 μg/m3) were significantly lower (p < 0.01, t-test) with respect to conventional cigarette (30.2 ± 1.5 μg/m3)
Assessing the virucidal activity of essential oils against feline calicivirus, a non-enveloped virus used as surrogate of norovirus
Full text linkNorovirus (NoV) causes serious gastrointestinal disease worldwide and is regarded as an important foodborne pathogen. Due the difficulties of in vitro cultivation for human NoV, alternative caliciviruses (i.e., feline calicivirus, FCV, or murine NoV) have long been used as surrogates for in vitro assessment of the efficacy of antivirals. Essential oils (EOs) are natural compounds that have displayed antimicrobial and antioxidant properties. We report in vitro the virucidal efficacy of four EOs, Melissa officinalis L. EO (MEO), Thymus vulgaris L. EO (TEO), Rosmarinus officinalis L. EO (REO), and Salvia officinalis L. EO (SEO) against FCV at different time contacts (10, 30 min, 1, 4 and 8 h). At the maximum non-cytotoxic concentration and at 10- and 100- fold concentrations over the cytotoxic threshold, the EOs did not decrease significantly FCV viral titers. However, MEO at 12,302.70 mu g/mL exhibited a significant efficacy decreasing the viral titer by 0.75 log10 Tissue Culture Infectious Dose (TCID50)/50 mu l after 10 min as compared to virus control. In this study, virucidal activity of four EOs against FCV, was investigated. A lack of virucidal efficacy of TEO, REO and SEO at different compound concentrations and time contacts against FCV was observed whilst MEO was able to significantly decrease FCV titer
Impact of biomass burning on PM10 concentrations
No full textThe combustion of pruning residues of olive trees in field is a common practice in South of Italy. Since fields are usually close to densely populated areas, the biomass burning emission may cause seasonally increasing exposure to air pollutants and may present a potential health risk for the population. The goal of this work was to carry out the chemical characterization of PM originated from open burning of agricultural biomass and to provide tracer species or concentration ratios characteristics of this source. In this work preliminary results about the chemical characterization of PM10 aerosol collected a few meters from the plume of a bonfire and throughout its duration are shown. In particular the data showed that during open burning of olive tree residues, PM10 mean concentrations were about fifty times higher than PM10 collected at background site in no biomass burning event. Moreover the particulate matter composition was especially enriched in K, OC, Pb and PAHs, and in particular in benz[a]anthracene and benzo[a]pyrene; this pollutants in fact show the biggest Enrichment Factor values. The BaP/BghiP ratio registered in biomass burning event (1.88) was three times greater than in no event condition (0.57); and this ratio result better than IP/[IP+BghiP] ratio for discriminating between two emission sources of PAHs, such as diesel exhaust and biomass burning. Finally BaA has been demonstrated to be a better marker of biomass combustion source with respect to BaP and the other PAHs
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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