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2.
Nanotoxicology ; 14(2): 275-286, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31928272

RESUMO

The major theme of the NRC report "Toxicity Testing in the Twenty-first Century" is to replace animal testing by using alternative in vitro methods. Therefore, it can be expected that in the future in vivo data will be replaced with in vitro data. Hence, there is a need for new strategies to make use of the increasing amount of in vitro data when developing human toxicological effect factors (HEF) to characterize the impact category of human toxicity in life cycle assessment (LCA). Here, we present a new approach for deriving HEF for manufactured nanomaterials (MNMs) based on the combined use of in vitro toxicity data and a relative potency factor (RPF) approach. In vitro toxicity tests with nano-CuO, nano-Ag and nano-ZnO and their corresponding ions were performed on THP-1, CaCo-2 and Hep-G2 cell lines. The ratio of the here calculated EC50 of the ionic form and the nanoform corresponds to the Relative Potency Factor (RPF). Using this approach, HEFs (case/kgintake) for the aforementioned nanoparticles were obtained. Non-carcinogenic HEFs (case/kgintake) for exposure via ingestion of 5.9E-01, 7.5E-03 and 2.5 E-02 were calculated for nano-Ag, nano-CuO and nano-ZnO, respectively. The HEF values here proposed were compared with HEF values extrapolated from in vivo toxicity data reported in the literature. The here presented procedure is the most appropriate approximation currently available for using in vitro toxicity data on MNM for application in the field of LCIA.


Assuntos
Cobre/toxicidade , Manufaturas/toxicidade , Nanopartículas Metálicas/toxicidade , Modelos Teóricos , Prata/toxicidade , Óxido de Zinco/toxicidade , Animais , Células CACO-2 , Sobrevivência Celular/efeitos dos fármacos , Células Hep G2 , Humanos , Íons , Medição de Risco , Células THP-1 , Testes de Toxicidade
3.
PLoS Biol ; 18(1): e3000589, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31922526

RESUMO

Electroporation is a basic yet powerful method for delivering small molecules (RNA, DNA, drugs) across cell membranes by application of an electrical field. It is used for many diverse applications, from genetically engineering cells to drug- and DNA-based vaccine delivery. Despite this broad utility, the high cost of electroporators can keep this approach out of reach for many budget-conscious laboratories. To address this need, we develop a simple, inexpensive, and handheld electroporator inspired by and derived from a common household piezoelectric stove lighter. The proposed "ElectroPen" device can cost as little as 23 cents (US dollars) to manufacture, is portable (weighs 13 g and requires no electricity), can be easily fabricated using 3D printing, and delivers repeatable exponentially decaying pulses of about 2,000 V in 5 ms. We provide a proof-of-concept demonstration by genetically transforming plasmids into Escherichia coli cells, showing transformation efficiency comparable to commercial devices, but at a fraction of the cost. We also demonstrate the potential for rapid dissemination of this approach, with multiple research groups across the globe validating the ease of construction and functionality of our device, supporting the potential for democratization of science through frugal tools. Thus, the simplicity, accessibility, and affordability of our device holds potential for making modern synthetic biology accessible in high school, community, and resource-poor laboratories.


Assuntos
Eletroporação/instrumentação , Técnicas de Transferência de Genes/instrumentação , Análise Custo-Benefício , Eletricidade , Eletroporação/economia , Desenho de Equipamento/economia , Escherichia coli , Técnicas de Transferência de Genes/economia , Humanos , Laboratórios/economia , Manufaturas/economia , Áreas de Pobreza , Impressão Tridimensional , Transformação Bacteriana , Transportes
4.
Ophthalmology ; 127(1): 27-37, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31543351

RESUMO

PURPOSE: To compare wear of standard, adjustable, and ready-made glasses among children. DESIGN: Randomized, controlled, open-label, noninferiority trial. PARTICIPANTS: Students aged 11 to 16 years with presenting visual acuity (VA) ≤6/12 in both eyes, correctable to ≥6/7.5, subjective spherical equivalent refractive error (SER) ≤-1.0 diopters (D), astigmatism and anisometropia both <2.00 D, and no other ocular abnormalities. METHODS: Participants were randomly allocated (1:1:1) to standard glasses, ready-made glasses, or adjustable glasses based on self-refraction. We recorded glasses wear on twice-weekly covert evaluation by head teachers (primary outcome), self-reported and investigator-observed wear, best-corrected visual acuity (BCVA) (not prespecified), children's satisfaction, and value attributed to glasses. MAIN OUTCOME MEASURE: Proportion of glasses wear on twice-weekly covert evaluation by head teachers over 2 months. RESULTS: Among 379 eligible participants, 127 were allocated to standard glasses (mean age, 13.7 years; standard deviation [SD], 1.0 years; 54.3% were male), 125 to ready-made (mean age, 13.6; SD, 0.83; 45.6%), and 127 to adjustable (mean age, 13.4 years; SD, 0.85; 54.3%). Mean wear proportion of adjustable glasses was significantly lower than for standard glasses (45% vs. 58%; P = 0.01), although the adjusted difference (90% confidence interval [CI], -19.0% to -3.0%) did not meet the prespecified inferiority threshold of 20%. Self-reported (90.2% vs. 84.8%, P = 0.64) and investigator-observed (44.1% vs. 33.9%, P = 0.89) wear did not differ between standard and adjustable glasses, nor did satisfaction with (P = 0.97) or value attributed to study glasses (P = 0.55) or increase in quality of life (5.53 [SD, 4.47] vs. 5.68 [SD, 4.34] on a 100-point scale, P > 0.30). Best-corrected visual acuity with adjustable glasses was better (P < 0.001) than with standard glasses. Change in power of study lenses at the end of the study (adjustable: 0.65 D, 95% CI, 0.52-0.79; standard, 0.01 D; 95% CI, -0.006 to 0.03, P < 0.001) was greater for adjustable glasses, although interobserver variation in power measurements may explain this. Lens scratches and frame damage were more common with adjustable glasses, whereas lens breakage was less common than for standard glasses. CONCLUSIONS: Proportion of wear was lower with adjustable glasses, although VA was better and measures of satisfaction and quality of life were not inferior to standard glasses.


Assuntos
Óculos , Manufaturas , Refração Ocular/fisiologia , Erros de Refração/terapia , Transtornos da Visão/terapia , Adolescente , Grupo com Ancestrais do Continente Asiático/etnologia , Criança , China/epidemiologia , Feminino , Humanos , Masculino , Aceitação pelo Paciente de Cuidados de Saúde/estatística & dados numéricos , Cooperação do Paciente , Satisfação do Paciente , Desenho de Prótese , Erros de Refração/etnologia , Erros de Refração/fisiopatologia , Inquéritos e Questionários , Transtornos da Visão/etnologia , Transtornos da Visão/fisiopatologia , Seleção Visual , Acuidade Visual/fisiologia
5.
Environ Technol ; 41(4): 488-497, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30028240

RESUMO

We present environmentally friendly brake pads produced with three different types of lignin, soda lignin (SL), sulphuric acid lignin (SAL) and heat-treated SAL (HL), as frictional materials to replace phenol formaldehyde resin (PFR, binder) and cashew nut shell liquid (CNSL, filler) in commercial automobile brake pad. Then the performance characteristics of the lignin-added brake pads were tested and compared using several fundamental tests. The results showed that lignin-added brake pads adhered to the SAE standard (0.25) for friction coefficient, which is the primary contributor to the performance of a braking system. In particular, the replacement of PFR with SL demonstrated a better friction coefficient than did replacement with SAL or HL, reaching up to 0.6. On the other hand, when lignin was substituted for CNSL as filler, HL-added brake pads showed a significant improvement in wear resistance of 0.12 g (dust generation) compared to SL and SAL, which had a resistance of approximately 0.25 g.


Assuntos
Automóveis , Lignina , Excipientes , Manufaturas , Polímeros
6.
Biofouling ; 35(8): 870-882, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31603038

RESUMO

Steel marine structures provide foci of biodiversity when they develop into artificial reefs. Development begins with deposition of a biofilm. The effects of contaminants from oil spills on biofilm microbiomes, microbially-induced corrosion (MIC) and metal loss may impact preservation of marine metal structures. A microcosm experiment exposed biofilms on carbon steel disks (CSDs) to crude oil, dispersant, and dispersed oil to address their impacts on bacterial composition and metal loss and pitting. Biofilm diversity increased over time in all exposures. Community composition in dispersant and dispersed oil treatments deviated from the controls for the duration of a 12-week experiment. As biofilms matured, Pseudomonadaceae increased while Rhodobacteraceae decreased in abundance in dispersed oil treatments compared to the controls and dispersant treatments. Greatest mass loss and deepest pitting on CSDs were observed in dispersed oil treatments, suggesting impacts manifest as a consequence of increased MIC potential on carbon steel.


Assuntos
Biofilmes/efeitos dos fármacos , Manufaturas/microbiologia , Microbiota/efeitos dos fármacos , Poluição por Petróleo/efeitos adversos , Proteobactérias/efeitos dos fármacos , Aço , Biodiversidade , Biofilmes/crescimento & desenvolvimento , Carbono/química , Corrosão , Petróleo/análise , Petróleo/toxicidade , Poluição por Petróleo/análise , Proteobactérias/classificação , Proteobactérias/isolamento & purificação , RNA Ribossômico 16S/genética , Aço/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
7.
Molecules ; 24(19)2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31574985

RESUMO

In this study, a technology for obtaining functional inorganic-organic hybrid materials was designed using waste polymers of natural origin, i.e., kraft lignin and magnesium lignosulfonate, and alumina as an inorganic component. Al2O3-lignin and Al2O3-lignosulfonate systems were prepared by a mechanical method using a mortar grinder and a planetary ball mill, which made it possible to obtain products of adequate homogeneity in an efficient manner. This was confirmed by the use of Fourier transform infrared spectroscopy and thermogravimetric analysis. In the next step, the developed hybrid materials were used as functional admixtures in cement mixtures, thus contributing to the formation of a modern, sustainable building material. How the original components and hybrid materials affected the mechanical properties of the resulting mortars was investigated. The admixture of biopolymers, especially lignin, led to cement composites characterized by greater plasticity, while alumina improved their strength properties. It was confirmed that the system containing 0.5 wt.% of alumina-lignin material is the most suitable for application as a cement mortar admixture.


Assuntos
Lignina/química , Manufaturas/análise , Óxido de Alumínio/química , Biopolímeros/química , Lignina/análogos & derivados , Magnésio/química , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria
8.
J Phys Chem Lett ; 10(20): 5997-6002, 2019 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-31545052

RESUMO

The classical method for evaluating the waveguide ability only focuses on the optical loss coefficient. However, for the micro- or submicroscale, an organic waveguide is demonstrated by the present study whose scale effect should not be neglected. We found that the optical loss coefficient increased remarkably when decreasing the sectional size of the microfibers. Furthermore, simulations based on Finite-Difference Time-Domain also demonstrated the size-dependent effect of the waveguide. Both the experimental and simulating results showed that the optical loss coefficient converges to a certain value, which means that the scale effect can be neglected as the sectional size is large enough. On the basis of the present study, we suggest that the scale-dependent effect on the sectional size of the waveguide should be investigated by evaluating the waveguide ability by the optical loss coefficient.


Assuntos
Cumarínicos/efeitos da radiação , ortoaminobenzoatos/efeitos da radiação , Cumarínicos/química , Cristalização , Fluorescência , Luz , Manufaturas/efeitos da radiação , Espectroscopia de Infravermelho com Transformada de Fourier , Eletricidade Estática , Difração de Raios X , ortoaminobenzoatos/química
9.
MMWR Morb Mortal Wkly Rep ; 68(38): 813-818, 2019 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-31557149

RESUMO

Silicosis is an incurable occupational lung disease caused by inhaling particles of respirable crystalline silica. These particles trigger inflammation and fibrosis in the lungs, leading to progressive, irreversible, and potentially disabling disease. Silica exposure is also associated with increased risk for lung infection (notably, tuberculosis), lung cancer, emphysema, autoimmune diseases, and kidney disease (1). Because quartz, a type of crystalline silica, is commonly found in stone, workers who cut, polish, or grind stone materials can be exposed to silica dust. Recently, silicosis outbreaks have been reported in several countries among workers who cut and finish stone slabs for countertops, a process known as stone fabrication (2-5). Most worked with engineered stone, a manufactured, quartz-based composite material that can contain >90% crystalline silica (6). This report describes 18 cases of silicosis, including the first two fatalities reported in the United States, among workers in the stone fabrication industry in California, Colorado, Texas, and Washington. Several patients had severe progressive disease, and some had associated autoimmune diseases and latent tuberculosis infection. Cases were identified through independent investigations in each state and confirmed based on computed tomography (CT) scan of the chest or lung biopsy findings. Silica dust exposure reduction and effective regulatory enforcement, along with enhanced workplace medical and public health surveillance, are urgently needed to address the emerging public health threat of silicosis in the stone fabrication industry.


Assuntos
Manufaturas/efeitos adversos , Indústria Manufatureira , Exposição Ocupacional/efeitos adversos , Silicose/diagnóstico , Adulto , California/epidemiologia , Colorado/epidemiologia , Evolução Fatal , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Índice de Gravidade de Doença , Silicose/epidemiologia , Texas/epidemiologia , Washington/epidemiologia
10.
Bioengineered ; 10(1): 397-408, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31526157

RESUMO

Nowadays, there is an increasing concern toward substituting the scarce wood fibers with alternative lignocellulosic fibers that originate from crop residue to reinforce biocomposites. In this paper, the potential application of coffee hull (CH) of the reinforced polyethylene (PE) matrix composites was studied for the first time. Experiments of composite that enhanced with CH on mechanical properties, hydroscopicity, thermogravimetric analysis, fiber treatment, and microstructures were tested in this study. The PE matrix was reinforced with varying volume fractions of CH and was studied. The results show that incorporation of coffee hull markedly improved the mechanical properties of the reinforced high-density polyethylene (HDPE) matrix composites. Micrographs show a strong interfacial adhesion between the CH fiber particles. This property may be the main reason for the stability between composites. At the same time this work investigated the effect of different treatments on the mechanical properties and water absorption behavior of composites. The fiber surface treatments were done using active chemicals such as calcium hydroxide (Ca(OH)2), silane coupling agent (SCA), maleic anhydride grafted polypropylene (MA-g-PP), stearic acid (SA), ethylene bis stearamide (EBS) and the combination (MA-g-PP, SA, EBS). The results show that (Ca(OH)2)treatment is the best way to improve its properties. Probably because attributed to removal of surface active functional groups (-OH) from the CH fiber and induction of hydrophobicity that in turn improved the compatibility with the polymer matrix. As a result, the use of coffee hull in composites could have great significance for the industry.


Assuntos
Café/química , Manufaturas , Plásticos/síntese química , Polietileno/química , Hidróxido de Cálcio/química , Humanos , Interações Hidrofóbicas e Hidrofílicas , Anidridos Maleicos/química , Teste de Materiais , Plásticos/química , Silanos/química , Ácidos Esteáricos/química , Temperatura , Resistência à Tração , Resíduos , Molhabilidade
11.
Molecules ; 24(18)2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31540149

RESUMO

Due to their numerous health benefits associated with various diseases and anti-oxidation properties, the phenolic compounds collectively referred to as phytochemicals have attracted a lot of interest, however, a single extraction method for polyphenols has not been developed yet. Supercritical fluid extraction, a green extraction method, provides the final product without organic solvent residues. In this work the extraction of lavender was performed using supercritical carbon dioxide. A statistical experimental design based on the Box-Behnken (B-B) method was planned, and the extraction yields and total phenolic contents were measured for three different variables: pressure, temperature and extraction time. The ranges were 200-300 bar, 40-60 °C and 15-45 min. The extracts yields from scCO2 extraction were in the range of 4.3-9.2 wt.%. The highest yield (9.2 wt.%) was achieved at a temperature of 60 °C under the pressure of 250 bar after 45 min. It also corresponded to the highest total phenolic content (10.17 mg GAE/g extract). Based on the study, the statistically generated optimal extraction conditions to obtain the highest total phenolic compounds concentration from flowers of Lavandula angustifolia were a temperature of 54.5 °C, pressure of 297.9 bar, and the time of 45 min. Based on the scavenging activity percentage (AA%) of scCO2 extracts, it is concluded that the increase of extraction pressure had a positive influence on the increase of AA% values.


Assuntos
Cromatografia com Fluido Supercrítico/métodos , Flores/química , Lavandula/química , Polifenóis/isolamento & purificação , Dióxido de Carbono/química , Manufaturas/economia , Fenóis/análise , Fenóis/isolamento & purificação , Extratos Vegetais/química , Polifenóis/análise , Pressão , Projetos de Pesquisa , Solventes/química , Temperatura , Tempo
12.
Biofouling ; 35(8): 819-831, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31558046

RESUMO

Biofilms can be formed on the surfaces of dairy processing equipment and are a potential source of product contamination. This study evaluated the diversity of multispecies biofilms formed on stainless steel (SS) due to the contaminating microbiota in raw milk. Samples of raw milk were used: one was fresh milk and the other maintained in refrigerated bulk tanks for up to 48 h. The mesophilic aerobic contamination was ∼104 CFU ml-1 in fresh milk and 106 CFU ml-1 in bulk milk. SS coupons were kept immersed in the milk at 7 ±2 °C for 10 days, and every two days, the raw milk was changed for samples of the same origin collected on the current day. After incubation for 10 days, sessile cells in the biofilm reached 105 CFU cm-2 in the presence of fresh milk, and 106 CFU cm-2 in the presence of bulk milk. The genetic diversity analysis showed that Gammaproteobacteria and Bacilli predominated in the biofilms throughout the incubation of both milk samples and these biofilms showed a reduction in diversity over time. The main classes of bacteria found in these biofilms have representatives of great importance since many of them have spoilage potential.


Assuntos
Biofilmes/crescimento & desenvolvimento , Contaminação de Equipamentos , Manufaturas/microbiologia , Microbiota , Leite/microbiologia , Aço Inoxidável , Animais , Contagem de Colônia Microbiana , Indústria de Laticínios/normas , Microbiologia de Alimentos
13.
Environ Sci Pollut Res Int ; 26(29): 29991-30002, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31414386

RESUMO

The microbial corrosion of oil and gas pipes is one of the problems occurring in the oil industry. Various mechanisms explaining microbial corrosion have been demonstrated. Commonly, biocorrosion is attributed to sulfate-reducing bacteria. Also, it has recently been reported that microbial species can connect their electron transport system to metal electrodes. In this research, two spore-forming bacteria isolated in different years from a gas pipeline were identified by biochemical techniques and by 16S rDNA amplification, sequencing, and comparison with the NCBI database. Isolates were also compared between them using molecular techniques as the restriction patterns, unique for 16S rDNA (ARDRA), and the profile of the amplified bit from the genomic DNA, using an unspecific primer (RAPD). The results obtained showed that both isolates corresponded to Clostridium celerecrescens with a 99% similarity according to the sequence reported on the NCBI database. Also, the ARDRA and RAPD electrophoretic profiles of both strains were identical, and no plasmids were found in the strains. Thus, it can be settled that this bacterium is persistent in the environment prevailing in gas pipelines. Also, it was demonstrated that the bacterial secretion of organic acids contributes to the pitting and general biocorrosion of API XL 52 steel. The rates of corrosion obtained, approximately after 40 days, were correlated with the presence and metabolic activity of C. celerecrescens on the metallic surfaces.


Assuntos
Biofilmes/crescimento & desenvolvimento , Clostridium/isolamento & purificação , Corrosão , Manufaturas/microbiologia , Aço , Anaerobiose , DNA Ribossômico/genética , RNA Ribossômico 16S/genética
14.
J Mater Sci Mater Med ; 30(8): 91, 2019 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-31388766

RESUMO

Customized porous titanium alloys have become the emerging materials for orthopaedic implant applications. In this work, diamond and rhombic dodecahedron porous Ti-33Nb-4Sn scaffolds were fabricated by selective laser melting (SLM). The phase, microstructure and defects characteristics were investigated systematically and correlated to the effects of pore structure, unit cell size and processing parameter on the mechanical properties of the scaffolds. Fine ß phase dendrites were obtained in Ti-33Nb-4Sn scaffolds due to the fast solidification velocity in SLM process. The compressive and bending strength of the scaffolds decrease with the decrease of strut size and diamond structures showed both higher compressive and bending strength than the dodecahedron structures. Diamond Ti-33Nb-4Sn scaffold with compressive strength of 76 MPa, bending strength of 127 MPa and elastic modulus of 2.3 GPa was achieved by SLM, revealing the potential of Ti-33Nb-4Sn scaffolds for applications on orthopaedic implant.


Assuntos
Nióbio/química , Equipamentos Ortopédicos , Próteses e Implantes , Estanho/química , Tecidos Suporte/química , Titânio/química , Ligas/síntese química , Ligas/química , Materiais Biocompatíveis , Fenômenos Biomecânicos , Força Compressiva , Módulo de Elasticidade , Manufaturas/análise , Teste de Materiais , Ortopedia , Porosidade , Próteses e Implantes/ultraestrutura , Estresse Mecânico , Propriedades de Superfície
15.
PLoS One ; 14(7): e0219089, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31269073

RESUMO

Vibrational behaviour of symmetric angle-ply layered circular cylindrical shell filled with quiescent fluid is presented. The equations of motion of cylindrical shell in terms of stress and moment resultants are derived from the first order shear deformation theory. Irrotational of inviscid fluid are expressed as the wave equation. These two equations are coupled. Strain-displacement relations and stress-strain relations are adopted into the equations of motion to obtain the differential equations with displacements and rotational functions. A system of ordinary differential equation is obtained in one variable by assuming the functions in separable form. Spline of order three is applied to approximate the displacement and rotational functions, together with boundary conditions, to get a generalised eigenvalue problem. The eigenvalue problem is solved for eigen frequency parameter and associate eigenvectors of spline coefficients. The study of frequency parameters are analysed using the parameters the thickness ratio, length ratio, angle-ply, properties of material and number of layers under different boundary conditions.


Assuntos
Manufaturas , Acústica , Elasticidade , Análise de Elementos Finitos , Hidrodinâmica , Modelos Teóricos , Movimento (Física) , Vibração
16.
Environ Sci Process Impacts ; 21(8): 1323-1333, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31289797

RESUMO

Semi-volatile organic compounds (SVOCs) are widely used in materials employed in vehicle interiors, causing poor in-cabin air quality. The emission characteristics of SVOCs from vehicle cabin materials can be characterized by two key parameters: the gas-phase SVOC concentration adjacent to the material surface (y0) and the convective mass transfer coefficient across the material surface (hm). Accurate determination of y0 and hm is fundamental in investigating SVOC emission principles and health risks. Considering that the steady state SVOC concentration (y) in a ventilated chamber changes with the ventilation rate (Q), we developed a varied ventilation rate (VVR) method to simultaneously measure y0 and hm for typical vehicle cabin materials. Experimental results for di(2-ethylhexyl)phthalate (DEHP) emissions from test materials indicated that the VVR method has the merits of simple operation, short testing time, and high accuracy. We also examined the influence of temperature (T) on y0 and hm, and found that both y0 and hm increase with increasing temperature. A theoretical correlation between y0 and T was then derived, indicating that the logarithm of y0T is linearly related to 1/T. Analysis based on the data from this study and from the literature validates the effectiveness of the derived correlation. Moreover, preliminary exposure analysis was performed to assess the health risk of DEHP in a vehicular environment.


Assuntos
Poluição do Ar em Ambientes Fechados/análise , Dietilexilftalato/análise , Manufaturas/análise , Veículos Automotores/normas , Compostos Orgânicos Voláteis/análise , Temperatura , Emissões de Veículos/análise , Ventilação
17.
Environ Sci Process Impacts ; 21(8): 1384-1392, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31246204

RESUMO

Certain processes in indoor air, such as deposition, partitioning, and heterogeneous reactions, involve interactions with surfaces. We have characterized the surface area, volume, shape, and material of objects in 10 bedrooms, nine kitchens, and three offices. The resolution of the measurements was ∼1 cm. The ratio of surface area with contents to that without contents did not vary by type of room and averaged 1.5 ± 0.3 (mean ± standard deviation) across all rooms. The ratio of the volume minus contents to nominal volume averaged 0.9 ± 0.1 and was lower for kitchens compared to bedrooms and offices. Ignoring contents, the surface-area-to-volume ratio was 1.8 ± 0.3 m-1; accounting for contents, the ratio was 3.2 ± 1.2 m-1, or 78% higher. These two ratios did not vary by type of room and were similar to those measured for 33 rooms in another study. Due to substantial differences in the design and contents of kitchens, their ratios had the highest variability among the three room types. The most common shape of surfaces was flat rectangular, while each room also had many irregularly-shaped objects. Paint-covered surfaces and stained wood were the two most common materials in each room, accounting for an average of 42% and 22% of total surface area, respectively, although the distribution of materials varied by room type. These findings have important implications for understanding the chemistry of indoor environments, as the available surface area for deposition, partitioning, and reactions is higher and more complex than assumed in simple models.


Assuntos
Poluição do Ar em Ambientes Fechados/análise , Habitação/normas , Manufaturas/análise , Humanos , Análise Espacial , Propriedades de Superfície
18.
Anal Bioanal Chem ; 411(20): 5297-5307, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31161322

RESUMO

The design and fabrication of a continuous-flow µPCR device with very short amplification time and low power consumption are presented. Commercially available, 4-layer printed circuit board (PCB) substrates are employed, with in-house designed yet industrially manufactured embedded Cu micro-resistive heaters lying at very close distance from the microfluidic network, where DNA amplification takes place. The 1.9-m-long microchannel in combination with desirably high flow velocities (for fast amplification) challenged the robustness of the sealing that was overcome with the development of a novel bonding method rendering the microdevice robust even at extreme pressure drops (12 bars). The proposed fabrication methods are PCB compatible, allowing for mass and reliable production of the µPCR device in the established PCB industry. The µPCR chip was successfully validated during the amplification of two different DNA fragments (and with different target DNA copies) corresponding to the exon 20 of the BRCA1 gene, and to the plasmid pBR322, a commonly used cloning vector in E. coli. Successful DNA amplification was demonstrated at total reaction times down to 2 min, with a power consumption of 2.7 W, rendering the presented µPCR one of the fastest and lowest power-consuming devices, suitable for implementation in low-resource settings. Detailed numerical calculations of the DNA residence time distributions, within an acceptable temperature range for denaturation, annealing, and extension, performed for the first time in the literature, provide useful information regarding the actual on-chip PCR protocol and justify the maximum volumetric flow rate for successful DNA amplification. The calculations indicate that the shortest amplification time is achieved when the device is operated at its enzyme kinetic limit (i.e., extension rate). Graphical abstract.


Assuntos
DNA/química , Dispositivos Lab-On-A-Chip , Manufaturas , Bifenilos Policlorados/química , Reação em Cadeia da Polimerase/métodos
19.
Int J Mol Sci ; 20(12)2019 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-31212901

RESUMO

A new biomimetic strategy to im prove the self-healing properties of Portland cement is presented that is based on the application of the biogenic inorganic polymer polyphosphate (polyP), which is used as a cement admixture. The data show that synthetic linear polyp, with an average chain length of 40, as well as natural long-chain polyP isolated from soil bacteria, has the ability to support self-healing of this construction material. Furthermore, polyP, used as a water-soluble Na-salt, is subject to Na+/Ca2+ exchange by the Ca2+ from the cement, resulting in the formation of a water-rich coacervate when added to the cement surface, especially to the surface of bacteria-containing cement/concrete samples. The addition of polyP in low concentrations (<1% on weight basis for the solids) not only accelerated the hardening of cement/concrete but also the healing of microcracks present in the material. The results suggest that long-chain polyP is a promising additive that increases the self-healing capacity of cement by mimicking a bacteria-mediated natural mechanism.


Assuntos
Materiais de Construção/análise , Manufaturas/análise , Materiais Biomiméticos/análise , Materiais Biomiméticos/química , Microscopia Eletrônica de Varredura , Modelos Teóricos , Polifosfatos/química , Análise Espectral , Água/química
20.
Inhal Toxicol ; 31(4): 131-146, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-31187656

RESUMO

Objectives: US water infrastructure is in need of widespread repair due to age-related deterioration. Currently, the cured-in-place (CIPP) procedure is the most common method for water pipe repair. This method involves the on-site manufacture of a new polymer composite plastic liner within the damaged pipe. The CIPP process can release materials resulting in occupational and public health concerns. To understand hazards associated with CIPP-related emission exposures, an in vitro toxicity assessment was performed. Materials and Methods: Mouse alveolar epithelial and alveolar macrophage cell lines and condensates collected at 3 worksites utilizing styrene-based resins were utilized for evaluations. All condensate samples were normalized based on the major emission component, styrene. Further, a styrene-only exposure group was used as a control to determine mixture related toxicity. Results: Cytotoxicity differences were observed between worksite samples, with the CIPP worksite 4 sample inducing the most cell death. A proteomic evaluation was performed, which demonstrated styrene-, worksite-, and cell-specific alterations. This examination of protein expression changes determined potential biomarkers of exposure including transglutaminase 2, advillin, collagen type 1, perilipin-2, and others. Pathway analysis of exposure-induced proteomic alterations identified MYC and p53 to be regulators of cellular responses. Protein changes were also related to pathways involved in cell damage, immune response, and cancer. Conclusions: Together these findings demonstrate potential risks associated with the CIPP procedure as well as variations between worksites regarding emissions and toxicity. Our evaluation identified biological pathways that require a future evaluation and also demonstrates that exposure assessment of CIPP worksites should examine multiple chemical components beyond styrene, as many cellular responses were styrene-independent.


Assuntos
Poluentes Ocupacionais do Ar/toxicidade , Monitoramento Ambiental/métodos , Células Epiteliais/efeitos dos fármacos , Macrófagos Alveolares/efeitos dos fármacos , Manufaturas/toxicidade , Estireno/toxicidade , Animais , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Células Epiteliais/imunologia , Células Epiteliais/metabolismo , Expressão Gênica/efeitos dos fármacos , Macrófagos Alveolares/imunologia , Macrófagos Alveolares/metabolismo , Camundongos , Estresse Oxidativo/efeitos dos fármacos , Proteoma/genética , Proteoma/metabolismo , Células RAW 264.7 , Local de Trabalho
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