Secured independent tools in peritoneoscopy.

PubMed

Tsin, Daniel A; Davila, Fausto; Dominguez, Guillermo; Manolas, Panagiotis

2010-01-01

Secured independent tools are being introduced to aid in peritoneoscopy. We present a simple technique for anchoring instruments, powered lights, and micro machines through the abdominal wall. We used a laparoscopic trainer, micro alligator clips with one or two 2-0 nylon tails and cables for engines and lights. The above instruments were introduced via a 12-mm or 15-mm port. Clips were placed for traction, retraction and exposure, lights for illumination, and motors for potential work. A laparoscopy port closure or suture passer was introduced percutaneously to grab and extract the tails or cables outside of the simulated abdominal cavity. The engines and lights were powered by a direct electric current (DC) plugged into exteriorized cables. We used 2 to 3 clips for each, and engines performed well. This basic simulation adds independent instruments, lights, and engines. We replaced cannulas with threads or cables in an attempt to limit the number of ports. This technique further opens the door for innovations in wired machines in laparoscopy, single-port laparoscopy, or natural orifice surgery.

Arsenic Exposure and Type 2 Diabetes: MicroRNAs as Mechanistic Links?

PubMed

Beck, Rowan; Styblo, Miroslav; Sethupathy, Praveen

2017-03-01

The goal of this review is to delineate the following: (1) the primary means of inorganic arsenic (iAs) exposure for human populations, (2) the adverse public health outcomes associated with chronic iAs exposure, (3) the pathophysiological connection between arsenic and type 2 diabetes (T2D), and (4) the incipient evidence for microRNAs as candidate mechanistic links between iAs exposure and T2D. Exposure to iAs in animal models has been associated with the dysfunction of several different cell types and tissues, including liver and pancreatic islets. Many microRNAs that have been identified as responsive to iAs exposure under in vitro and/or in vivo conditions have also been shown in independent studies to regulate processes that underlie T2D etiology, such as glucose-stimulated insulin secretion from pancreatic beta cells. Defects in insulin secretion could be, in part, associated with aberrant microRNA expression and activity. Additional in vivo studies need to be performed with standardized concentrations and durations of arsenic exposure in order to evaluate rigorously microRNAs as molecular drivers of iAs-associated diabetes.

Survey of residential 50 Hz EMF exposure from transformer stations.

PubMed

Szabó, Judit; Jánossy, Gábor; Thuróczy, György

2007-01-01

In Hungary it is typical that 10/04 kV transformer stations are being installed in multistory residential and office buildings. Magnetic fields (MFs) up to several tens of microT have been measured in apartments close to transformers. The aim of the present study was to provide systematic assessment of MF exposure of residents living above transformer stations. Out of 41 addresses provided by the electricity supplier, current load of 21 transformers and MF in 21 apartments was measured. Spot MFs at 1 m height and time weighted average 24 h MF exposure at bed height was measured. All-day personal MF exposure was measured at waist and HOME exposure was calculated. BED exposure was measured at bed height. Participants kept a time-activity diary. The time-weighted average 24 h MF exposure (3.03 microT) exceeded the usual residential exposure (<0.2 microT). The mean HOME and BED personal exposure above transformers was 0.825 and 1.033 microT, respectively. Our study provides exposure assessment of a cohort with a wider exposure range, compared to power-line epidemiological studies.

Comparative MicroRNA Expression Patterns in Fibroblasts after Low and High Doses of Low-LET Radiation Exposure

NASA Technical Reports Server (NTRS)

Maes, Olivier C.; Xu, Suying; Hada, Megumi; Wu, Honglu; Wang, Eugenia

2007-01-01

Exposure to ionizing radiation causes DNA damage to cells, and provokes a plethora of cellular responses controlled by unique gene-directed signaling pathways. MicroRNAs (miRNAs) are small (22-nucleotide), non-coding RNAs which functionally silence gene expression by either degrading the messages or inhibiting translation. Here we investigate radiation-dependent changes in these negative regulators by comparing the expression patterns of all 462 known human miRNAs in fibroblasts, after exposure to low (0.1 Gy) or high (2 Gy) doses of X-rays at 30 min, 2, 6 and 24 hrs post-treatment. The expression patterns of microRNAs after low and high doses of radiation show a similar qualitative down-regulation trend at early (0.5 hr) and late (24 hr) time points, with a quantitatively steeper slope following the 2 Gy exposures. Interestingly, an interruption of this downward trend is observed after the 2 Gy exposure, i.e. a significant up-regulation of microRNAs at 2 hrs, then reverting to the downward trend by 6 hrs; this interruption at the intermediate time point was not observed with the 0.1 Gy exposure. At the early time point (0.5 hr), candidate gene targets of selected down-regulated microRNAs, common to both 0.1 and 2 Gy exposures, were those functioning in chromatin remodeling. Candidate target genes of unique up-regulated microRNAs seen at a 2 hr intermediate time point, after the 2 Gy exposure only, are those involved in cell death signaling. Finally, putative target genes of down-regulated microRNAs seen at the late (24 hr) time point after either doses of radiation are those involved in the up-regulation of DNA repair, cell signaling and homeostasis. Thus we hypothesize that after radiation exposure, microRNAs acting as hub negative regulators for unique signaling pathways needed to be down-regulated so as to de-repress their target genes for the proper cellular responses, including DNA repair and cell maintenance. The unique microRNAs up-regulated at 2 hr after 2 Gy suggest the cellular response to functionally suppress the apoptotic death signaling reflex after exposure to high dose radiation. Further analyses with transcriptome and global proteomic profiling will validate the reciprocal expression of signature microRNAs selected in our radiation-exposed cells, and their candidate target gene families, and test our hypothesis that unique radiation-specific microRNAs are keys in governing signaling responses for damage control of this environmental hazard.

Development of Minimally Invasive Medical Tools Using Laser Processing on Cylindrical Substrates

NASA Astrophysics Data System (ADS)

Haga, Yoichi; Muyari, Yuta; Goto, Shoji; Matsunaga, Tadao; Esashi, Masayoshi

This paper reports micro-fabrication techniques using laser processing on cylindrical substrates for the realization of high-performance multifunctional minimally invasive medical tools with small sizes. A spring-shaped shape memory alloy (SMA) micro-coil with a square cross section has been fabricated by spiral cutting of a Ti-Ni SMA tube with a femtosecond laser. Small diameter active bending catheter which is actuated by hydraulic suction mechanism for intravascular minimally invasive diagnostics and therapy has also been developed. The catheter is made of a Ti-Ni super elastic alloy (SEA) tube which is processed by laser micromachining and a silicone rubber tube which covers the outside of the SEA tube. The active catheter is effective for insertion in branch of blood vessel which diverse in acute angle which is difficult to proceed. Multilayer metallization and patterning have been performed on glass tubes with 2 and 3 mm external diameters using maskless lithography techniques using a laser exposure system. Using laser soldering technique, a integrated circuit parts have been mounted on a multilayer circuit patterned on a glass tube. These fabrication techniques will effective for realization of high-performance multifunctional catheters, endoscopic tools, and implanted small capsules.

Improved Hyperthermia Treatment of Tumors Under Consideration of Magnetic Nanoparticle Distribution Using Micro-CT Imaging.

PubMed

Dähring, H; Grandke, J; Teichgräber, U; Hilger, I

2015-12-01

Heterogeneous magnetic nanoparticle (MNP) distributions within tumors can cause regions of temperature under dosage and reduce the therapeutic efficiency. Here, micro-computed tomography (CT) imaging was used as a tool to determine the MNP distribution in vivo. The therapeutic success was evaluated based on tumor volume and temperature distribution. Tumor-bearing mice were intratumorally injected with iron oxide particles. MNP distribution was assessed by micro-CT with a low radiation dose protocol. MNPs were clearly visible, and the exact distribution to nontumor structures was detected by micro-CT. Knowledge of the intratumoral MNP distribution allowed the generation of higher temperatures within the tumor and led to higher temperature values after exposure to an alternating magnetic field (AMF). Consequently, the tumor size after 28 days was reduced to 14 and 73 % of the initial tumor volume for the MNP/AMF/CT and MNP/AMF groups, respectively. The MNP distribution pattern mainly governed the generated temperature spots in the tumor. Knowing the MNP distribution enabled individualized hyperthermia treatment and improved the overall therapeutic efficiency.

Estimation of tool wear compensation during micro-electro-discharge machining of silicon using process simulation

NASA Astrophysics Data System (ADS)

Muralidhara, .; Vasa, Nilesh J.; Singaperumal, M.

2010-02-01

A micro-electro-discharge machine (Micro EDM) was developed incorporating a piezoactuated direct drive tool feed mechanism for micromachining of Silicon using a copper tool. Tool and workpiece materials are removed during Micro EDM process which demand for a tool wear compensation technique to reach the specified depth of machining on the workpiece. An in-situ axial tool wear and machining depth measurement system is developed to investigate axial wear ratio variations with machining depth. Stepwise micromachining experiments on silicon wafer were performed to investigate the variations in the silicon removal and tool wear depths with increase in tool feed. Based on these experimental data, a tool wear compensation method is proposed to reach the desired depth of micromachining on silicon using copper tool. Micromachining experiments are performed with the proposed tool wear compensation method and a maximum workpiece machining depth variation of 6% was observed.

Exposure of welders and other metal workers to ELF magnetic fields.

PubMed

Skotte, J H; Hjøllund, H I

1997-01-01

This study assessed exposure to extremely low frequency (ELF) magnetic fields of welders and other metal workers and compared exposure from different welding processes. Exposure to ELF magnetic fields was measured for 50 workers selected from a nationwide cohort of metal workers and 15 nonrandomly selected full-time welders in a shipyard. The measurements were carried out with personal exposure meters during 3 days of work for the metal workers and I day of work for the shipyard welders. To record a large dynamic range of ELF magnetic field values, the measurements were carried out with "high/low" pairs of personal exposure meters. Additional measurements of static magnetic fields at fixed positions close to welding installations were done with a Hall-effect fluxmeter. The total time of measurement was 1273 hours. The metal workers reported welding activity for 5.8% of the time, and the median of the work-period mean exposure to ELF magnetic fields was 0.18 microT. DC metal inert or active gas welding (MIG/MAG) was used 80% of the time for welding, and AC manual metal arc welding (MMA) was used 10% of the time. The shipyard welders reported welding activity for 56% of the time, and the median and maximum of the workday mean exposure to ELF magnetic fields was 4.70 and 27.5 microT, respectively. For full-shift welders the average workday mean was 21.2 microT for MMA welders and 2.3 microT for MIG/MAG welders. The average exposure during the effective time of welding was estimated to be 65 microT for the MMA welding process and 7 microT for the MIG/MAG welding process. The time of exposure above 1 microT was found to be a useful measure of the effective time of welding. Large differences in exposure to ELF magnetic fields were found between different groups of welders, depending on the welding process and effective time of welding. MMA (AC) welding caused roughly 10 times higher exposure to ELF magnetic fields compared with MIG/MAG (DC) welding. The measurements of static fields suggest that the combined exposure to static and ELF fields of MIG/MAG (DC) welders and the exposure to ELF fields of MMA (AC) welders are roughly of the same level.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pogribny, Igor P., E-mail: igor.pogribny@fda.hhs.g

Human exposure to certain natural and man-made chemical carcinogens is one of the major risk factors for cancer development. The effect of chemical carcinogens on genetic and epigenetic alterations and their significance in the development of cancer has been well-established. In contrast, the role of microRNAs (miRNAs) in the etiology of chemical-associated cancers remains relatively unexplored despite extensive reports on changes in miRNA expression upon carcinogen exposure. This review summarizes the current knowledge for the role of miRNAs as drivers of chemical-induced carcinogenesis by bridging the gap between carcinogen exposure and cancer development through functional studies. It also emphasizes themore » potential for miRNA changes as early indicators of the carcinogenic process, markers for carcinogen exposure, and identification of chemical carcinogenic hazards. - Highlights: • Exposure to chemical carcinogens alters microRNA expression. • MicroRNA alterations may have significance in the development of cancer. • MicroRNAs may be early indicators of the carcinogenic process and carcinogen exposure.« less

GPS-based microenvironment tracker (MicroTrac) model to estimate time–location of individuals for air pollution exposure assessments: Model evaluation in central North Carolina

PubMed Central

Breen, Michael S.; Long, Thomas C.; Schultz, Bradley D.; Crooks, James; Breen, Miyuki; Langstaff, John E.; Isaacs, Kristin K.; Tan, Yu-Mei; Williams, Ronald W.; Cao, Ye; Geller, Andrew M.; Devlin, Robert B.; Batterman, Stuart A.; Buckley, Timothy J.

2014-01-01

A critical aspect of air pollution exposure assessment is the estimation of the time spent by individuals in various microenvironments (ME). Accounting for the time spent in different ME with different pollutant concentrations can reduce exposure misclassifications, while failure to do so can add uncertainty and bias to risk estimates. In this study, a classification model, called MicroTrac, was developed to estimate time of day and duration spent in eight ME (indoors and outdoors at home, work, school; inside vehicles; other locations) from global positioning system (GPS) data and geocoded building boundaries. Based on a panel study, MicroTrac estimates were compared with 24-h diary data from nine participants, with corresponding GPS data and building boundaries of home, school, and work. MicroTrac correctly classified the ME for 99.5% of the daily time spent by the participants. The capability of MicroTrac could help to reduce the time–location uncertainty in air pollution exposure models and exposure metrics for individuals in health studies. PMID:24619294

Proline accumulation in lemongrass (Cymbopogon flexuosus Stapf.) due to heavy metal stress.

PubMed

Handique, G K; Handique, A K

2009-03-01

Toxic heavy metals viz. lead, mercury and cadmium induced differential accumulation of proline in lemongrass (Cymbopogon flexuosus Stapf.) grown in soil amended with 50, 100, 200, 350 and 500 mg kg(-1) of the metals have been studied. Proline accumulation was found to be metal specific, organ specific and linear dose dependant. Further, proline accumulation following short term exposure (two months after transplantation) was higher than long term exposure (nine months after transplantation). Proline accumulation following short term exposure was 2.032 to 3.839 micro moles g(-1) for cadmium (50-200 mg kg(-1)); the corresponding range for mercury was 1.968 to 5.670 micro moles g(-1) and 0.830 to 4.567 micro moles g(-1) for lead (50-500 mg kg(-1) for mercury and lead). Proline accumulation was consistently higher in young tender leaf than old leaf, irrespective of the metal or duration of exposure. For cadmium treatment proline level was 2.032 to 3.839 micro moles g(-1) for young leaves while the corresponding value for old leaf was 1.728 to 2.396 micro moles g(-1) following short term exposure. The same trend was observed for the other two metals and duration of exposure. For control set proline accumulation in root was 0.425 micro moles g(-1) as against 0.805 and 0.533 micro moles g(-1) in young and old leaves respectively indicating that proline accumulation in root are lower than leaves, under both normal and stressed condition.

Air Pollution Exposure Modeling for Health Studies | Science ...

EPA Pesticide Factsheets

Dr. Michael Breen is leading the development of air pollution exposure models, integrated with novel personal sensor technologies, to improve exposure and risk assessments for individuals in health studies. He is co-investigator for multiple health studies assessing the exposure and effects of air pollutants. These health studies include participants with asthma, diabetes, and coronary artery disease living in various U.S. cities. He has developed, evaluated, and applied novel exposure modeling and time-activity tools, which includes the Exposure Model for Individuals (EMI), GPS-based Microenvironment Tracker (MicroTrac) and Exposure Tracker models. At this seminar, Dr. Breen will present the development and application of these models to predict individual-level personal exposures to particulate matter (PM) for two health studies in central North Carolina. These health studies examine the association between PM and adverse health outcomes for susceptible individuals. During Dr. Breen’s visit, he will also have the opportunity to establish additional collaborations with researchers at Harvard University that may benefit from the use of exposure models for cohort health studies. These research projects that link air pollution exposure with adverse health outcomes benefit EPA by developing model-predicted exposure-dose metrics for individuals in health studies to improve the understanding of exposure-response behavior of air pollutants, and to reduce participant

Experimental evaluation of tool run-out in micro milling

NASA Astrophysics Data System (ADS)

Attanasio, Aldo; Ceretti, Elisabetta

2018-05-01

This paper deals with micro milling cutting process focusing the attention on tool run-out measurement. In fact, among the effects of the scale reduction from macro to micro (i.e., size effects) tool run-out plays an important role. This research is aimed at developing an easy and reliable method to measure tool run-out in micro milling based on experimental tests and an analytical model. From an Industry 4.0 perspective this measuring strategy can be integrated into an adaptive system for controlling cutting forces, with the objective of improving the production quality, the process stability, reducing at the same time the tool wear and the machining costs. The proposed procedure estimates the tool run-out parameters from the tool diameter, the channel width, and the phase angle between the cutting edges. The cutting edge phase measurement is based on the force signal analysis. The developed procedure has been tested on data coming from micro milling experimental tests performed on a Ti6Al4V sample. The results showed that the developed procedure can be successfully used for tool run-out estimation.

Challenges for allergy diagnosis in regions with complex pollen exposures.

PubMed

Barber, Domingo; Díaz-Perales, Araceli; Villalba, Mayte; Chivato, Tomas

2015-02-01

Over the past few decades, significant scientific progress has influenced clinical allergy practice. The biological standardization of extracts was followed by the massive identification and characterization of new allergens and their progressive use as diagnostic tools including allergen micro arrays that facilitate the simultaneous testing of more than 100 allergen components. Specific diagnosis is the basis of allergy practice and is always aiming to select the best therapeutic or avoidance intervention. As a consequence, redundant or irrelevant information might be adding unnecessary cost and complexity to daily clinical practice. A rational use of the different diagnostic alternatives would allow a significant improvement in the diagnosis and treatment of allergic patients, especially for those residing in complex pollen exposure areas.

Flexible Micro-and Nano-Patterning Tools for Photonics

DTIC Science & Technology

2016-03-10

AFRL-AFOSR-VA-TR-2016-0125 Flexible Micro- and Nano -Patterning Tools for Photonics Henry Smith LUMARRAY INC. 15 WARD ST. SOMERVILLE, MA 21434228 03...14-01-2015 4.  TITLE AND SUBTITLE Flexible Micro- and Nano -Patterning Tools for Photonics - OSD STTR Phase 2 5a.  CONTRACT NUMBER FA9550-12-C-0082 5b...2016https://livelink.ebs.afrl.af.mil/livelink/llisapi.dll DISTRIBUTION A: Distribution approved for public release. FLEXIBLE MICRO- AND NANO - PATTERNING

Micro electrical discharge milling using deionized water as a dielectric fluid

NASA Astrophysics Data System (ADS)

Chung, Do Kwan; Kim, Bo Hyun; Chu, Chong Nam

2007-05-01

In electrical discharge machining, dielectric fluid is an important factor affecting machining characteristics. Generally, kerosene and deionized water have been used as dielectric fluids. In micro electrical discharge milling, which uses a micro electrode as a tool, the wear of the tool electrode decreases the machining accuracy. However, the use of deionized water instead of kerosene can reduce the tool wear and increase the machining speed. This paper investigates micro electrical discharge milling using deionized water. Deionized water with high resistivity was used to minimize the machining gap. Machining characteristics such as the tool wear, machining gap and machining rate were investigated according to resistivity of deionized water. As the resistivity of deionized water decreased, the tool wear was reduced, but the machining gap increased due to electrochemical dissolution. Micro hemispheres were machined for the purpose of investigating machining efficiency between dielectric fluids, kerosene and deionized water.

Micro Slot Generation by μ-ED Milling

NASA Astrophysics Data System (ADS)

Dave, H. K.; Mayanak, M. K.; Rajpurohit, S. R.; Mathai, V. J.

2016-08-01

Micro electro discharge machining is one of the most widely used advanced micro machining technique owing to its capability to fabricate micro features on any electrically conductive materials irrespective of its material properties. Despite its wide acceptability, the process is always adversely affected by issues like wear that occurred on the tool electrode, which results into generation of inaccurate features. Micro ED milling, a process variant in which the tool electrode simultaneously rotated and scanned during machining, is reported to have high process efficiency for generation of 3D complicated shapes and features with relatively less electrode wear intensity. In the present study an attempt has been made to study the effect of two process parameters viz. capacitance and scanning speed of tool electrode on end wear that occurs on the tool electrode and overcut of micro slots generated by micro ED milling. The experiment has been conducted on Al 1100 alloy with tungsten electrode having diameter of 300 μm. Results suggest that wear on the tool electrode and overcut of the micro features generated are highly influenced by the level of the capacitance employed during machining. For the parameter usage employed for present study however, no significant effect of variation of scanning speed has been observed on both responses.

A Study on Micro-Machining Technology for the Machining of NiTi: Five-Axis Micro-Milling and Micro Deep-Hole Drilling

NASA Astrophysics Data System (ADS)

Biermann, D.; Kahleyss, F.; Krebs, E.; Upmeier, T.

2011-07-01

Micro-sized applications are gaining more and more relevance for NiTi-based shape memory alloys (SMA). Different types of micro-machining offer unique possibilities for the manufacturing of NiTi components. The advantage of machining is the low thermal influence on the workpiece. This is important, because the phase transformation temperatures of NiTi SMAs can be changed and the components may need extensive post manufacturing. The article offers a simulation-based approach to optimize five-axis micro-milling processes with respect to the special material properties of NiTi SMA. Especially, the influence of the various tool inclination angles is considered for introducing an intelligent tool inclination optimization algorithm. Furthermore, aspects of micro deep-hole drilling of SMAs are discussed. Tools with diameters as small as 0.5 mm are used. The possible length-to-diameter ratio reaches up to 50. This process offers new possibilities in the manufacturing of microstents. The study concentrates on the influence of the cutting speed, the feed and the tool design on the tool wear and the quality of the drilled holes.

Individual estimation of exposures to extremely low frequency magnetic fields in jobs commonly held by women.

PubMed

Deadman, J E; Infante-Rivard, C

2002-02-15

Exposures to extremely low frequency (ELF) magnetic fields have not been documented extensively in occupations besides the work environments of electric or telephone utilities. A 1980-1993 study of childhood acute lymphoblastic leukemia (ALL) in Québec, Canada, gathered detailed information about the occupations of 491 mothers of ALL cases and mothers of a similar number of healthy controls. This information was combined with published data on the intensities of ELF magnetic fields associated with sources or work environments to estimate ELF magnetic field exposures for a wide range of jobs commonly held by women. Estimated exposures for 61 job categories ranged from 0.03 to 0.68 microT; the 25th, 50th, and 75th percentiles were 0.135, 0.17, and 0.23 microT, respectively. By job category, the most highly exposed jobs (>0.23 microT) included bakery worker, cashier, cook and kitchen worker, electronics worker, residential and industrial sewing machine operator, and textile machine operator. By work environment, the most highly exposed job categories were electronics worker in an assembly plant (0.70 microT) and sewing machine operators in a textile factory (0.68 microT) and shoe factory (0.66 microT). These results provide new information on expected levels of exposure in a wide range of jobs commonly held by women.

Effects of chromium(III) picolinate on cortisol and DHEAs secretion in H295R human adrenocortical cells.

PubMed

Kim, Beob G; Adams, Julye M; Jackson, Brian A; Lindemann, Merlin D

2010-02-01

Dietary chromium(III) picolinate (CrPic) effects on circulating steroid hormones have been reported in various experimental animals. However, direct effects of CrPic on adrenocortical steroidogenesis are uncertain. Therefore, the objective was to determine the effects of CrPic on cortisol and dehydroepiandrosterone sulfate (DHEAs) secretion from H295R cells. In experiment 1, a 24-h exposure to CrPic (0 to 200 microM) had both linear (p < 0.001) and quadratic (p < 0.001) effects on cortisol secretion from forskolin-stimulated cells with the highest cortisol secretion at 0.1 microM of CrPic and the lowest at 200 microM of CrPic. In experiment 2, a 48-h exposure to CrPic (200 microM) decreased cortisol (p < 0.07) release from forskolin-stimulated cells during a 24-h collection period. In experiment 3, a 48-h exposure to CrPic (100 microM) decreased cortisol (p < 0.05) and DHEAs (p < 0.01) from forskolin-stimulated cells during a 24-h sampling period. In experiment 4, a 24-h exposure to forskolin followed by a 24-h exposure to both forskolin and CrPic (100 and 200 microM) decreased both cortisol and DHEAs secretion (p < 0.01). This study suggests that at high concentrations, CrPic inhibits aspects of steroidogenesis in agonist-stimulated adrenocortical cells.

Modeling and evaluating of surface roughness prediction in micro-grinding on soda-lime glass considering tool characterization

NASA Astrophysics Data System (ADS)

Cheng, Jun; Gong, Yadong; Wang, Jinsheng

2013-11-01

The current research of micro-grinding mainly focuses on the optimal processing technology for different materials. However, the material removal mechanism in micro-grinding is the base of achieving high quality processing surface. Therefore, a novel method for predicting surface roughness in micro-grinding of hard brittle materials considering micro-grinding tool grains protrusion topography is proposed in this paper. The differences of material removal mechanism between convention grinding process and micro-grinding process are analyzed. Topography characterization has been done on micro-grinding tools which are fabricated by electroplating. Models of grain density generation and grain interval are built, and new predicting model of micro-grinding surface roughness is developed. In order to verify the precision and application effect of the surface roughness prediction model proposed, a micro-grinding orthogonally experiment on soda-lime glass is designed and conducted. A series of micro-machining surfaces which are 78 nm to 0.98 μm roughness of brittle material is achieved. It is found that experimental roughness results and the predicting roughness data have an evident coincidence, and the component variable of describing the size effects in predicting model is calculated to be 1.5×107 by reverse method based on the experimental results. The proposed model builds a set of distribution to consider grains distribution densities in different protrusion heights. Finally, the characterization of micro-grinding tools which are used in the experiment has been done based on the distribution set. It is concluded that there is a significant coincidence between surface prediction data from the proposed model and measurements from experiment results. Therefore, the effectiveness of the model is demonstrated. This paper proposes a novel method for predicting surface roughness in micro-grinding of hard brittle materials considering micro-grinding tool grains protrusion topography, which would provide significant research theory and experimental reference of material removal mechanism in micro-grinding of soda-lime glass.

GPS-based Microenvironment Tracker (MicroTrac) Model to ...

EPA Pesticide Factsheets

A critical aspect of air pollution exposure assessment is the estimation of the time spent by individuals in various microenvironments (ME). Accounting for the time spent in different ME with different pollutant concentrations can reduce exposure misclassifications, while failure to do so can add uncertainty and bias to risk estimates. In this study, a classification model, called MicroTrac, was developed to estimate time of day and duration spent in eight ME (indoors and outdoors at home, work, school; inside vehicles; other locations) from global positioning system (GPS) data and geocoded building boundaries. Based on a panel study, MicroTrac estimates were compared to 24 h diary data from 7 participants on workdays and 2 participants on nonworkdays, with corresponding GPS data and building boundaries of home, school, and work. MicroTrac correctly classified the ME for 99.5% of the daily time spent by the participants. The capability of MicroTrac could help to reduce the time-location uncertainty in air pollution exposure models and exposure metrics for individuals in health studies. The National Exposure Research Laboratory’s (NERL’s) Human Exposure and Atmospheric Sciences Division (HEASD) conducts research in support of EPA’s mission to protect human health and the environment. HEASD’s research program supports Goal 1 (Clean Air) and Goal 4 (Healthy People) of EPA’s strategic plan. More specifically, our division conducts research to characterize

Updating the Micro-Tom TILLING platform.

PubMed

Okabe, Yoshihiro; Ariizumi, Tohru; Ezura, Hiroshi

2013-03-01

The dwarf tomato variety Micro-Tom is regarded as a model system for functional genomics studies in tomato. Various tomato genomic tools in the genetic background of Micro-Tom have been established, such as mutant collections, genome information and a metabolomic database. Recent advances in tomato genome sequencing have brought about a significant need for reverse genetics tools that are accessible to the larger community, because a great number of gene sequences have become available from public databases. To meet the requests from the tomato research community, we have developed the Micro-Tom Targeting-Induced Local Lesions IN Genomes (TILLING) platform, which is comprised of more than 5000 EMS-mutagenized lines. The platform serves as a reverse genetics tool for efficiently identifying mutant alleles in parallel with the development of Micro-Tom mutant collections. The combination of Micro-Tom mutant libraries and the TILLING approach enables researchers to accelerate the isolation of desirable mutants for unraveling gene function or breeding. To upgrade the genomic tool of Micro-Tom, the development of a new mutagenized population is underway. In this paper, the current status of the Micro-Tom TILLING platform and its future prospects are described.

Dose-responsiveness and persistence of microRNA expression alterations induced by cigarette smoke in mouse lung.

PubMed

Izzotti, Alberto; Larghero, Patrizia; Longobardi, Mariagrazia; Cartiglia, Cristina; Camoirano, Anna; Steele, Vernon E; De Flora, Silvio

2011-12-01

Our previous studies demonstrated that exposure to cigarette smoke (CS), either mainstream or environmental, results in a remarkable downregulation of microRNA expression in the lung of both mice and rats. The goals of the present study were to evaluate the dose responsiveness to CS and the persistence of microRNA alterations after smoking cessation. ICR (CD-1) neonatal mice were exposed whole-body to mainstream CS, at the doses of 119, 292, 438, and 631mg/m(3) of total particulate matter. Exposure started within 12h after birth and continued daily for 4 weeks. The levels of bulky DNA adducts and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) were measured by (32)P postlabeling procedures, and the expression of 697 mouse microRNAs was analyzed by microarray. The highest CS dose was lethal. Exposure to CS caused a dose-dependent increase of DNA alterations. DNA adducts and, even more sharply, 8-oxodGuo were reverted 1 and 4 weeks after smoking cessation. Exposure to CS resulted in an evident dysregulation of microRNA expression profiles, mainly in the sense of downregulation. The two lowest doses were not particularly effective, while the highest nonlethal dose produced extensive microRNA alterations. The expression of most downregulated microRNAs, including among others 7 members of the let-7 family, was restored one week after smoking cessation. However, the recovery was incomplete for a limited array of microRNAs, including mir-34b, mir-345, mir-421, mir-450b, mir-466, and mir-469. Thus, it appears that microRNAs mainly behave as biomarkers of effect and that exposure to high-dose, lasting for an adequate period of time, is needed to trigger the CS-related carcinogenesis process in the experimental animal model used. Copyright © 2011 Elsevier B.V. All rights reserved.

Chemoprevention of Cigarette Smoke–Induced Alterations of MicroRNA Expression in Rat Lungs

PubMed Central

Izzotti, Alberto; Calin, George A.; Steele, Vernon E.; Cartiglia, Cristina; Longobardi, Mariagrazia; Croce, Carlo M.; De Flora, Silvio

2015-01-01

We previously showed that exposure to environmental cigarette smoke (ECS) for 28 days causes extensive downregulation of microRNA expression in the lungs of rats, resulting in the overexpression of multiple genes and proteins. In the present study, we evaluated by microarray the expression of 484 microRNAs in the lungs of either ECS-free or ECS-exposed rats treated with the orally administered chemopreventive agents N-acetylcysteine, oltipraz, indole-3-carbinol, 5,6-benzoflavone, and phenethyl isothiocyanate (as single agents or in combinations). This is the first study of microRNA modulation by chemopreventive agents in nonmalignant tissues. Scatterplot, hierarchical cluster, and principal component analyses of microarray and quantitative PCR data showed that none of the above chemopreventive regimens appreciably affected the baseline microRNA expression, indicating potential safety. On the other hand, all of them attenuated ECS-induced alterations but to a variable extent and with different patterns, indicating potential preventive efficacy. The main ECS-altered functions that were modulated by chemopreventive agents included cell proliferation, apoptosis, differentiation, Ras activation, P53 functions, NF-κB pathway, transforming growth factor–related stress response, and angiogenesis. Some micro-RNAs known to be polymorphic in humans were downregulated by ECS and were protected by chemopreventive agents. This study provides proof-of-concept and validation of technology that we are further refining to screen and prioritize potential agents for continued development and to help elucidate their biological effects and mechanisms. Therefore, microRNA analysis may provide a new tool for predicting at early carcinogenesis stages both the potential safety and efficacy of cancer chemopreventive agents. PMID:20051373

Methods of in-vivo mouse lung micro-CT

NASA Astrophysics Data System (ADS)

Recheis, Wolfgang A.; Nixon, Earl; Thiesse, Jacqueline; McLennan, Geoffrey; Ross, Alan; Hoffman, Eric

2005-04-01

Micro-CT will have a profound influence on the accumulation of anatomical and physiological phenotypic changes in natural and transgenetic mouse models. Longitudinal studies will be greatly facilitated, allowing for a more complete and accurate description of events if in-vivo studies are accomplished. The purpose of the ongoing project is to establish a feasible and reproducible setup for in-vivo mouse lung micro-computed tomography (μCT). We seek to use in-vivo respiratory-gated μCT to follow mouse models of lung disease with subsequent recovery of the mouse. Methodologies for optimizing scanning parameters and gating for the in-vivo mouse lung are presented. A Scireq flexiVent ventilated the gas-anesthetized mice at 60 breaths/minute, 30 cm H20 PEEP, 30 ml/kg tidal volume and provided a respiratory signal to gate a Skyscan 1076 μCT. Physiologic monitoring allowed the control of vital functions and quality of anesthesia, e.g. via ECG monitoring. In contrary to longer exposure times with ex-vivo scans, scan times for in-vivo were reduced using 35μm pixel size, 158ms exposure time and 18μm pixel size, 316ms exposure time to reduce motion artifacts. Gating via spontaneous breathing was also tested. Optimal contrast resolution was achieved at 50kVp, 200μA, applying an aluminum filter (0.5mm). There were minimal non-cardiac related motion artifacts. Both 35μm and 1μm voxel size images were suitable for evaluation of the airway lumen and parenchymal density. Total scan times were 30 and 65 minutes respectively. The mice recovered following scanning protocols. In-vivo lung scanning with recovery of the mouse delivered reasonable image quality for longitudinal studies, e.g. mouse asthma models. After examining 10 mice, we conclude μCT is a feasible tool evaluating mouse models of lung pathology in longitudinal studies with increasing anatomic detail available for evaluation as one moves from in-vivo to ex-vivo studies. Further developments include automated bronchial tree segmentation and airway wall thickness measurement tools. Improvements in Hounsfield unit calibration have to be performed when the interest of the study lies in determining and quantifying parenchymal changes and rely on estimating partial volume contributions of underlying structures to voxel densities.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Giggleman, M.A.; Fitzpatrick, L.C.; Goven, A.J.

Earthworms, Lumbricus terrestris, exposed for 96 h to filter paper saturated with five nominal concentrations of pentachlorophenol, exhibited a 50% lethal concentration (LC50) of 25.0 {micro}g PCP/cm{sup 2} and corresponding whole worm body burden-based 50% lethal dose (LD50) of 877.7 {micro}g PCP/g dry mass. Linear regression modeling showed that worms increased body concentrations (BC = {micro}g PCP/g dry tissue mass) with increasing exposure concentrations (EC) according to BC = 113.5 + 29.5EC. Phagocytosis of yeast cells by immunoactive coelomocytes was suppressed only at body concentrations (863.3 {micro}g PCP/g dry mass) that approximated the calculated LD50 and overlapped those demonstrating lethality,more » indicating a sharp transition between sublethal and lethal toxicity. An exposure concentration of 15 {micro}g PCP/cm{sup 2} produced significant suppression of phagocytosis of yeast cells by immunoactive coelomocytes. However, the average measured body burden from this group approximated the estimated LD50, indicating a sharp toxic response slope. Exposure to 10 {micro}g PCP/cm{sup 2} with a corresponding body concentration of 501.3 {micro}g PCP/g dry mass did not affect phagocytosis. The importance of body burden data is emphasized.« less

Radiation exposure and radiation protection of the physician in iodine-131 Lipiodol therapy of liver tumours.

PubMed

Risse, J H; Ponath, C; Palmedo, H; Menzel, C; Grünwald, F; Biersack, H J

2001-07-01

Intra-arterial iodine-131 labelled Lipiodol therapy for liver cancer has been investigated for safety and efficacy over a number of years, but data on radiation exposure of personnel have remained unavailable to date. The aim of this study was to assess the radiation exposure of the physician during intra-arterial 131I-Lipiodol therapy for liver malignancies and to develop appropriate radiation protection measures and equipment. During 20 intra-arterial administrations of 131I-Lipiodol (1110-1924 MBq), radiation dose equivalents (RDE) to the whole body, fingers and eyes of the physician were determined for (a) conventional manual administration through a shielded syringe, (b) administration with an automatic injector and (c) administration with a lead container developed in-house. Administration by syringe resulted in a finger RDE of 19.5 mSv, an eye RDE of 130-140 microSv, and a whole-body RDE of 108-119 microSv. The injector reduced the finger RDE to 5 mSv. With both technique (a) and technique (b), contamination of angiography materials was observed. The container allowed safe transport and administration of the radiopharmaceutical from 4 m distance and reduced the finger RDE to <3 microSv and the eye RDE to <1 microSv during injection. During femoral artery compression, radiation exposure to the fingers reached 170 microSv, but the whole-body dose could be reduced from a mean RDE of 114 microSv to 14 microSv. No more contamination occurred. In conclusion, radiation exposure was high when 131I-Lipiodol was administered by syringe or injector, but was significantly reduced with the lead container.

Comparison of Personal PM2.5 Exposure in Various Micro-Environments during Haze and Clean Days in Nanjing

NASA Astrophysics Data System (ADS)

Zhang, T.

2015-12-01

There is a long term trend of haze in East China. As a main component of haze, fine particle (PM2.5) in various micro-environments (MEs) is a cause for concern regarding the environment and public health. To estimate individual PM2.5 exposures in distinct, non-residential MEs and to determine exposure characteristics during haze and clean days, we conducted personal PM2.5 monitoring with portable PM2.5 personal environment monitors (MicroPEM) in 19 indoor/outdoor MEs in Nanjing, and compared personal exposure data with ambient PM2.5 levels. Personal PM2.5 exposure patterns displayed notable spatial variance, peaking in snack streets and restaurants and dipping in subways and labs. Under both haze and non-haze conditions, different characteristics of MEs and the background PM2.5 level jointly determine the spatial variance of individual exposure. Indoor MEs with better ventilation systems led to lower personal PM2.5 exposure levels. During haze days, impact from high ambient PM2.5 overwhelms influence from other factors and dominates personal exposure trends.

A novel technique for micro-hole forming on skull with the assistance of ultrasonic vibration.

PubMed

Li, Zhe; Yang, Daoguo; Hao, Weidong; Wu, Tiecheng; Wu, Song; Li, Xiaoping

2016-04-01

Micro-hole opening on skull is technically challenging and is hard to realize by micro-drilling. Low-stiffness of the drill bit is a serious drawback in micro-drilling. To deal with this problem, a novel ultrasonic vibration assisted micro-hole forming technique has been developed. Tip geometry and vibration amplitude are two key factors affecting the performance of this hole forming technique. To investigate their effects, experiment was carried out with 300μm diameter tools of three different tip geometries at three different vibration amplitudes. Hole forming performance was evaluated by the required thrust force, dimensional accuracy, exit burr and micro-structure of bone tissue around the generated hole. Based on the findings from current study, the 60° conically tipped tool helps generate a micro-hole of better quality at a smaller thrust force, and it is more suitable for hole forming than the 120° conically tipped tool and the blunt tipped tool. As for the vibration amplitude, when a larger amplitude is used, a micro-hole of better quality and higher dimensional accuracy can be formed at a smaller thrust force. Findings from this study would lay a technical foundation for accurately generating a high-quality micro-hole on skull, which enables minimally invasive insertion of a microelectrode into brain for neural activity measuring. Copyright © 2015 Elsevier Ltd. All rights reserved.

Determination of Specific Forces and Tool Deflections in Micro-milling of Ti-6Al-4V alloy using Finite Element Simulations and Analysis

NASA Astrophysics Data System (ADS)

Farina, Simone; Thepsonti, Thanongsak; Ceretti, Elisabetta; Özel, Tugrul

2011-05-01

Titanium alloys offer superb properties in strength, corrosion resistance and biocompatibility and are commonly utilized in medical devices and implants. Micro-end milling process is a direct and rapid fabrication method for manufacturing medical devices and implants in titanium alloys. Process performance and quality depend upon an understanding of the relationship between cutting parameters and forces and resultant tool deflections to avoid tool breakage. For this purpose, FE simulations of chip formation during micro-end milling of Ti-6Al-4V alloy with an ultra-fine grain solid carbide two-flute micro-end mill are investigated using DEFORM software. At first, specific forces in tangential and radial directions of cutting during micro-end milling for varying feed advance and rotational speeds have been determined using designed FE simulations for chip formation process. Later, these forces are applied to the micro-end mill geometry along the axial depth of cut in 3D analysis of ABAQUS. Consequently, 3D distributions for tool deflections & von Misses stress are determined. These analyses will yield in establishing integrated multi-physics process models for high performance micro-end milling and a leap-forward to process improvements.

Thoracoabdominal Computed Tomography in Trauma Patients: A Cost-Consequences Analysis

PubMed Central

van Vugt, Raoul; Kool, Digna R.; Brink, Monique; Dekker, Helena M.; Deunk, Jaap; Edwards, Michael J.

2014-01-01

Background: CT is increasingly used during the initial evaluation of blunt trauma patients. In this era of increasing cost-awareness, the pros and cons of CT have to be assessed. Objectives: This study was performed to evaluate cost-consequences of different diagnostic algorithms that use thoracoabdominal CT in primary evaluation of adult patients with high-energy blunt trauma. Materials and Methods: We compared three different algorithms in which CT was applied as an immediate diagnostic tool (rush CT), a diagnostic tool after limited conventional work-up (routine CT), and a selective tool (selective CT). Probabilities of detecting and missing clinically relevant injuries were retrospectively derived. We collected data on radiation exposure and performed a micro-cost analysis on a reference case-based approach. Results: Both rush and routine CT detected all thoracoabdominal injuries in 99.1% of the patients during primary evaluation (n = 1040). Selective CT missed one or more diagnoses in 11% of the patients in which a change of treatment was necessary in 4.8%. Rush CT algorithm costed € 2676 (US$ 3660) per patient with a mean radiation dose of 26.40 mSv per patient. Routine CT costed € 2815 (US$ 3850) and resulted in the same radiation exposure. Selective CT resulted in less radiation dose (23.23 mSv) and costed € 2771 (US$ 3790). Conclusions: Rush CT seems to result in the least costs and is comparable in terms of radiation dose exposure and diagnostic certainty with routine CT after a limited conventional work-up. However, selective CT results in less radiation dose exposure but a slightly higher cost and less certainty. PMID:25337521

Improvement of the tool life of a micro-end mill using nano-sized SiC/Ni electroplating method.

PubMed

Park, Shinyoung; Kim, Kwang-Su; Roh, Ji Young; Jang, Gyu-Beom; Ahn, Sung-Hoon; Lee, Caroline Sunyong

2012-04-01

High mechanical properties of a tungsten carbide micro-end-mill tool was achieved by extending its tool life by electroplating nano-sized SiC particles (< 100 nm) that had a hardness similar to diamond in a nickel-based material. The co-electroplating method on the surface of the micro-end-mill tool was applied using SiC particles and Ni particles. Organic additives (saccharin and ammonium chloride) were added in a Watts bath to improve the nickel matrix density in the electroplating bath and to smooth the surface of the co-electroplating. The morphology of the coated nano-sized SiC particles and the composition were measured using Scanning Electron Microscope and Energy Dispersive Spectrometer. As the Ni/SiC co-electroplating layer was applied, the hardness and friction coefficient improved by 50%. Nano-sized SiC particles with 7 wt% were deposited on the surface of the micro-end mill while the Ni matrix was smoothed by adding organic additives. The tool life of the Ni/SiC co-electroplating coating on the micro-end mill was at least 25% longer than that of the existing micro-end mills without Ni/SiC co-electroplating. Thus, nano-sized SiC/Ni coating by electroplating significantly improves the mechanical properties of tungsten carbide micro-end mills.

miRanalyzer: a microRNA detection and analysis tool for next-generation sequencing experiments.

PubMed

Hackenberg, Michael; Sturm, Martin; Langenberger, David; Falcón-Pérez, Juan Manuel; Aransay, Ana M

2009-07-01

Next-generation sequencing allows now the sequencing of small RNA molecules and the estimation of their expression levels. Consequently, there will be a high demand of bioinformatics tools to cope with the several gigabytes of sequence data generated in each single deep-sequencing experiment. Given this scene, we developed miRanalyzer, a web server tool for the analysis of deep-sequencing experiments for small RNAs. The web server tool requires a simple input file containing a list of unique reads and its copy numbers (expression levels). Using these data, miRanalyzer (i) detects all known microRNA sequences annotated in miRBase, (ii) finds all perfect matches against other libraries of transcribed sequences and (iii) predicts new microRNAs. The prediction of new microRNAs is an especially important point as there are many species with very few known microRNAs. Therefore, we implemented a highly accurate machine learning algorithm for the prediction of new microRNAs that reaches AUC values of 97.9% and recall values of up to 75% on unseen data. The web tool summarizes all the described steps in a single output page, which provides a comprehensive overview of the analysis, adding links to more detailed output pages for each analysis module. miRanalyzer is available at http://web.bioinformatics.cicbiogune.es/microRNA/.

Serum microRNA biomarker identification in a residential cohort with elevated polychlorinated biphenyl exposures

EPA Science Inventory

Exposure to liver toxicants can result in or exacerbate fatty liver disease. Recent evidence suggests that serum-derived microRNAs (miRs) may improve identification of chemical-induced fatty liver disease relative to traditional protein-based biomarkers alone. Historical serum sa...

Exposure to 50 Hz magnetic field in apartment buildings with built-in transformer stations in Hungary.

PubMed

Thuróczy, György; Jánossy, Gábor; Nagy, Noémi; Bakos, József; Szabó, Judit; Mezei, Gábor

2008-01-01

Exposure to 50 Hz magnetic field (MF) was evaluated in 31 multi-level apartment buildings with built-in step-down transformer stations. In each building, three apartments were selected: one apartment located immediately above the transformer room (index apartment), one located on the same floor and one on a higher floor. The mean value of measured MFs was 0.98 microT in apartments above transformers, 0.13 microT on the same floor, and 0.1 microT in on higher floors. The mean measured MF value was higher than 0.2 microT in 30 (97%) index apartments, 4 (14%) on the same floor as the index apartments and 4 (13%) on higher floors. The corresponding numbers were 25 (81%), 0 and 0, respectively, when 0.4 microT was used as cut-point. It is concluded that apartments in building with built-in transformers can be reliably classified into high and low-exposure categories based on their location in relation to transformers.

Micro rotary machine and methods for using same

DOEpatents

Stalford, Harold L [Norman, OK

2012-04-17

A micro rotary machine may include a micro actuator and a micro shaft coupled to the micro actuator. The micro shaft comprises a horizontal shaft and is operable to be rotated by the micro actuator. A micro tool is coupled to the micro shaft and is operable to perform work in response to motion of the micro shaft.

Micro rotary machine and methods for using same

DOEpatents

Stalford, Harold

2015-01-13

A micro rotary machine may include a micro actuator and a micro shaft coupled to the micro actuator. The micro shaft comprises a horizontal shaft and is operable to be rotated by the micro actuator. A micro tool is coupled to the micro shaft and is operable to perform work in response to motion of the micro shaft.

Fabrication of cylindrical micro-parts using synchronous rotary scan-projection lithography and chemical etching

NASA Astrophysics Data System (ADS)

Ito, Kaiki; Suzuki, Yuta; Horiuchi, Toshiyuki

2017-07-01

Lithographical patterning on the surface of a fine pipe with a thin wall is required for fabricating three-dimensional micro-parts. For this reason, a new exposure system for printing patterns on a cylindrical pipe by synchronous rotary scan-projection exposure was developed. Using the exposure system, stent-like resist patterns with a width of 251 μm were printed on a surface of stainless-steel pipe with an outer diameter of 2 mm. The exposure time was 30 s. Next, the patterned pipe was chemically etched. As a result, a stent-like mesh pipe with a line width of 230 μm was fabricated. It was demonstrated that the new method had a potential to be applied to fabrications of stent and other cylindrical micro-parts.

A Flexure-Based Tool Holder for Sub-(micro)m Positioning of a Single Point Cutting Tool on a Four-axis Lathe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bono, M J; Hibbard, R L

2005-12-05

A tool holder was designed to facilitate the machining of precision meso-scale components with complex three-dimensional shapes with sub-{micro}m accuracy on a four-axis lathe. A four-axis lathe incorporates a rotary table that allows the cutting tool to swivel with respect to the workpiece to enable the machining of complex workpiece forms, and accurately machining complex meso-scale parts often requires that the cutting tool be aligned precisely along the axis of rotation of the rotary table. The tool holder designed in this study has greatly simplified the process of setting the tool in the correct location with sub-{micro}m precision. The toolmore » holder adjusts the tool position using flexures that were designed using finite element analyses. Two flexures adjust the lateral position of the tool to align the center of the nose of the tool with the axis of rotation of the B-axis, and another flexure adjusts the height of the tool. The flexures are driven by manual micrometer adjusters, each of which provides a minimum increment of motion of 20 nm. This tool holder has simplified the process of setting a tool with sub-{micro}m accuracy, and it has significantly reduced the time required to set a tool.« less

Method of fabricating a micro machine

DOEpatents

Stalford, Harold L

2014-11-11

A micro machine may be in or less than the micrometer domain. The micro machine may include a micro actuator and a micro shaft coupled to the micro actuator. The micro shaft is operable to be driven by the micro actuator. A tool is coupled to the micro shaft and is operable to perform work in response to at least motion of the micro shaft.

Methods and systems for micro machines

DOEpatents

Stalford, Harold L.

2018-03-06

A micro machine may be in or less than the micrometer domain. The micro machine may include a micro actuator and a micro shaft coupled to the micro actuator. The micro shaft is operable to be driven by the micro actuator. A tool is coupled to the micro shaft and is operable to perform work in response to at least motion of the micro shaft.

Methods and systems for micro machines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stalford, Harold L.

2017-04-11

A micro machine may be in or less than the micrometer domain. The micro machine may include a micro actuator and a micro shaft coupled to the micro actuator. The micro shaft is operable to be driven by the micro actuator. A tool is coupled to the micro shaft and is operable to perform work in response to at least motion of the micro shaft.

Methods and systems for micro machines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stalford, Harold L.

A micro machine may be in or less than the micrometer domain. The micro machine may include a micro actuator and a micro shaft coupled to the micro actuator. The micro shaft is operable to be driven by the micro actuator. A tool is coupled to the micro shaft and is operable to perform work in response to at least motion of the micro shaft.

Deposition and micro electrical discharge machining of CVD-diamond layers incorporated with silicon

NASA Astrophysics Data System (ADS)

Kühn, R.; Berger, T.; Prieske, M.; Börner, R.; Hackert-Oschätzchen, M.; Zeidler, H.; Schubert, A.

2017-10-01

In metal forming, lubricants have to be used to prevent corrosion or to reduce friction and tool wear. From an economical and ecological point of view, the aim is to avoid the usage of lubricants. For dry deep drawing of aluminum sheets it is intended to apply locally micro-structured wear-resistant carbon based coatings onto steel tools. One type of these coatings are diamond layers prepared by chemical vapor deposition (CVD). Due to the high strength of diamond, milling processes are unsuitable for micro-structuring of these layers. In contrast to this, micro electrical discharge machining (micro EDM) is a suitable process for micro-structuring CVD-diamond layers. Due to its non-contact nature and its process principle of ablating material by melting and evaporating, it is independent of the hardness, brittleness or toughness of the workpiece material. In this study the deposition and micro electrical discharge machining of silicon incorporated CVD-diamond (Si-CVD-diamond) layers were presented. For this, 10 µm thick layers were deposited on molybdenum plates by a laser-induced plasma CVD process (LaPlas-CVD). For the characterization of the coatings RAMAN- and EDX-analyses were conducted. Experiments in EDM were carried out with a tungsten carbide tool electrode with a diameter of 90 µm to investigate the micro-structuring of Si-CVD-diamond. The impact of voltage, discharge energy and tool polarity on process speed and resulting erosion geometry were analyzed. The results show that micro EDM is a suitable technology for micro-structuring of silicon incorporated CVD-diamond layers.

Research on the EDM Technology for Micro-holes at Complex Spatial Locations

NASA Astrophysics Data System (ADS)

Y Liu, J.; Guo, J. M.; Sun, D. J.; Cai, Y. H.; Ding, L. T.; Jiang, H.

2017-12-01

For the demands on machining micro-holes at complex spatial location, several key technical problems are conquered such as micro-Electron Discharge Machining (micro-EDM) power supply system’s development, the host structure’s design and machining process technical. Through developing low-voltage power supply circuit, high-voltage circuit, micro and precision machining circuit and clearance detection system, the narrow pulse and high frequency six-axis EDM machining power supply system is developed to meet the demands on micro-hole discharging machining. With the method of combining the CAD structure design, CAE simulation analysis, modal test, ODS (Operational Deflection Shapes) test and theoretical analysis, the host construction and key axes of the machine tool are optimized to meet the position demands of the micro-holes. Through developing the special deionized water filtration system to make sure that the machining process is stable enough. To verify the machining equipment and processing technical developed in this paper through developing the micro-hole’s processing flow and test on the real machine tool. As shown in the final test results: the efficient micro-EDM machining pulse power supply system, machine tool host system, deionized filtration system and processing method developed in this paper meet the demands on machining micro-holes at complex spatial locations.

Micro-computed tomography of false starts produced on bone by different hand-saws.

PubMed

Pelletti, Guido; Viel, Guido; Fais, Paolo; Viero, Alessia; Visentin, Sindi; Miotto, Diego; Montisci, Massimo; Cecchetto, Giovanni; Giraudo, Chiara

2017-05-01

The analysis of macro- and microscopic characteristics of saw marks on bones can provide useful information about the class of the tool utilized to produce the injury. The aim of the present study was to test micro-computed tomography (micro-CT) for the analysis of false starts experimentally produced on 32 human bone sections using 4 different hand-saws in order to verify the potential utility of micro-CT for distinguishing false starts produced by different saws and to correlate the morphology of the tool with that of the bone mark. Each sample was analysed through stereomicroscopy and micro-CT. Stereomicroscopic analysis allowed the identification of the false starts and the detection of the number of tool marks left by each saw. Micro-CT scans, through the integration of 3D renders and multiplanar reconstructions (MPR), allowed the identification of the shape of each false start correlating it to the injuring tool. Our results suggest that micro-CT could be a useful technique for assessing false starts produced by different classes of saws, providing accurate morphological profiles of the bone marks with all the advantages of high resolution 3D imaging (e.g., high accuracy, non-destructive analysis, preservation and documentation of evidence). However, further studies are necessary to integrate qualitative data with quantitative metrical analysis in order to further characterize the false start and the related injuring tool. Copyright © 2017 Elsevier B.V. All rights reserved.

Analyzing the effect of tool edge radius on cutting temperature in micro-milling process

NASA Astrophysics Data System (ADS)

Liang, Y. C.; Yang, K.; Zheng, K. N.; Bai, Q. S.; Chen, W. Q.; Sun, G. Y.

2010-10-01

Cutting heat is one of the important physical subjects in the cutting process. Cutting heat together with cutting temperature produced by the cutting process will directly have effects on the tool wear and the life as well as on the workpiece processing precision and surface quality. The feature size of the workpiece is usually several microns. Thus, the tiny changes of cutting temperature will affect the workpiece on the surface quality and accuracy. Therefore, cutting heat and temperature generated in micro-milling will have significantly different effect than the one in the traditional tools cutting. In this paper, a two-dimensional coupled thermal-mechanical finite element model is adopted to determine thermal fields and cutting temperature during the Micro-milling process, by using software Deform-2D. The effect of tool edge radius on effective stress, effective strain, velocity field and cutting temperature distribution in micro-milling of aluminum alloy Al2024-T6 were investigated and analyzed. Also, the transient cutting temperature distribution was simulated dynamically. The simulation results show that the cutting temperature in Micro-milling is lower than those occurring in conventional milling processes due to the small loads and low cutting velocity. With increase of tool edge radius, the maximum temperature region gradually occurs on the contact region between finished surfaced and flank face of micro-cutter, instead of the rake face or the corner of micro-cutter. And this phenomenon shows an obvious size effect.

Inactivation of bacteria by a mixed argon and oxygen micro-plasma as a function of exposure time.

PubMed

Weng, Chih-Chiang; Wu, Yi-Te; Liao, Juinn-Der; Kao, Chi-Yuan; Chao, Chih-Cheng; Chang, Juu-En; Hsu, Bo-Wen

2009-04-01

A radio-frequency dielectric barrier discharge (DBD) was applied as a micro-plasma device for the inactivation of bacteria, e.g., Escherichia coli. The cultured bacteria were placed on a polydimethyl siloxane (PDMS) film and placed inside the DBD cavity. The bacteria were exposed to micro-plasmas of varying oxygen/argon ratios for different exposure times. The survival of the bacteria was measured by determining bacterial growth using optical methods. The excited oxygen species increased with the increase in the oxygen to argon ratio as measured by optical emission spectroscopy (OES), but the increase of excited oxygen species in argon micro-plasma did not enhance the inactivation of bacteria. In contrast, increases in the time the bacteria were exposed to the micro-plasma were of importance. The results show that a continuous plasma flow containing energetic and reactive species may result in electro-physical interactions with bacteria exposed to the plasma leading to their inactivation. For currently-employed DBD device, addition of 0.5% oxygen to the argon micro-plasma for an exposure time of 30 sec was optimum for the inactivation of E. coli.

Exposures to estradiol, ethinylestradiol and octylphenol affect survival and growth of Rana pipiens and Rana sylvatica tadpoles.

PubMed

Hogan, Natacha S; Lean, David R S; Trudeau, Vance L

2006-08-01

Endocrine disrupting compounds (EDCs) are often detected in the aquatic environment and can negatively affect the health of wildlife populations. However, little is known about the sensitivity of native amphibians to EDCs. Wood frogs (Rana sylvatica) and Northern leopard frogs (Rana pipiens) were exposed to three estrogenic EDCs: estradiol (E2), ethinylestradiol (EE2), and 4-tert-octylphenol (OP). In addition, R. pipiens were exposed during two developmental stages (Gosner stages 26 and 36) to examine life-stage differences in sensitivity. Tadpoles were exposed for 2 wk to 8 nominal concentrations (0.25 microM-10 microM) of each compound. Individual mortality was recorded during the exposure period, while body weight was measured at the end of 2 wk. LC50 values were calculated, and differences in body weight between vehicle control and exposed groups were assessed. Rank order toxicity of the compounds for both R. pipiens stages and both species was OP > EE2 > E2. Gosner stage 26 tadpoles were more sensitive (LC50: E2 [5.57 microM], EE2 [3.01 microM], OP [1.36 microM]) to all three compounds when compared to stage 36 tadpoles (LC50: E2 [>10 microM], EE2 [4.17 microM], OP [2.80 microM]). Interspecies comparisons revealed R. sylvatica tadpoles (LC50: E2 [2.50 microM], EE2 [1.89 microM], OP [0.74 microM]) as being more sensitive to the three compounds than R. pipiens (LC50: E2 [4.56 microM], EE2 [2.75 microM], OP [1.42 microM]). Xenoestrogen exposure also affected tadpole body weight which may have long-term adverse effects on the rate of metamorphosis. These results provide toxicological data needed for assessing sublethal effects of estrogenic compounds on amphibian development and suggest that environmental levels of OP may pose a serious risk to the health of amphibian populations.

Evaluation of take-home organophosphorus pesticide exposure among agricultural workers and their children.

PubMed Central

Curl, Cynthia L; Fenske, Richard A; Kissel, John C; Shirai, Jeffry H; Moate, Thomas F; Griffith, William; Coronado, Gloria; Thompson, Beti

2002-01-01

We analyzed organophosphorus pesticide exposure in 218 farm worker households in agricultural communities in Washington State to investigate the take-home pathway of pesticide exposure and to establish baseline exposure levels for a community intervention project. House dust samples (n = 156) were collected from within the homes, and vehicle dust samples (n = 190) were collected from the vehicles used by the farm workers to commute to and from work. Urine samples were obtained from a farm worker (n = 213) and a young child (n = 211) in each household. Dust samples were analyzed for six pesticides, and urine samples were analyzed for five dialkylphosphate (DAP) metabolites. Azinphosmethyl was detected in higher concentrations (p < 0.0001) than the other pesticides: geometric mean concentrations of azinphosmethyl were 0.53 micro g/g in house dust and 0.75 micro g/g in vehicle dust. Dimethyl DAP metabolite concentrations were higher than diethyl DAP metabolite concentrations in both child and adult urine (p < 0.0001). Geometric mean dimethyl DAP concentrations were 0.13 micro mol/L in adult urine and 0.09 micro mol/L in child urine. Creatinine-adjusted geometric mean dimethyl DAP concentrations were 0.09 micro mol/g in adult urine and 0.14 micro mol/g in child urine. Azinphosmethyl concentrations in house dust and vehicle dust from the same household were significantly associated (r2 = 0.41, p < 0.0001). Dimethyl DAP levels in child and adult urine from the same household were also significantly associated (r2 = 0.18, p < 0.0001), and this association remained when the values were creatinine adjusted. The results of this work support the hypothesis that the take-home exposure pathway contributes to residential pesticide contamination in agricultural homes where young children are present. PMID:12460819

Differential patterns of injury to the proximal tubule of renal cortical slices following in vitro exposure to mercuric chloride, potassium dichromate, or hypoxic conditions.

PubMed

Ruegg, C E; Gandolfi, A J; Nagle, R B; Brendel, K

1987-09-15

The innate susceptibility of renal cell types to these agents was investigated using precision-cut rabbit renal cortical slices made perpendicular to the cortical-papillary axis. Slices were incubated in DME/F12 medium containing 10 microM, 100 microM, or 1 mM concentrations of either metal for 12 hr or in Krebs-Hepes buffer gassed with nitrogen (100%) for 0.75 to 5 hr of hypoxic exposure. To simulate postischemic reperfusion, some slices were transferred to vessels gassed with oxygen after an initial hypoxic period. Mercuric chloride (100 microM) exposure resulted in damage to the straight regions of proximal tubules by 12 hr leaving convoluted regions unaffected. Hypoxia (2.25 hr) and potassium dichromate (100 microM for 12 hr) both caused injury to the convoluted proximal tubules without affecting straight proximal tubular regions. Mercury concentrations of 10 microM and 1 mM had no effect or injured all cell types within the slice, respectively. Similar results were observed for hypoxic periods less than 1.5 hr or greater than 3 hr of exposure. Potassium dichromate had no measurable affect at 10 microM, but at 1 mM focal lesions were observed after 4 hr of exposure, and by 12 hr all cell types within the slice were affected. Intracellular potassium content normalized to DNA correlated well, but always preceded the pathological lesions observed. These results demonstrate that injury to specific regions of the proximal tubule by these agents relates to an innate susceptibility of the intoxicated cell type independent of physiologic feedback or blood delivery patterns proposed as mechanisms of selective injury from in vivo studies.

Modeling and control for micro and nano manipulation

NASA Astrophysics Data System (ADS)

Wejinya, Uchechukwu C.

Manipulation of micro and nano entities implies the movement of micro and nano entities from an initial position (location) to the desire position (location). This operation is not only necessary, but a required task with great precision. The tools needed for the manipulation needs to be chosen properly because the capabilities of the human hand are very restricted. Smart micro and nano manipulation are becoming of great interest in many applications including medicine and industry. In industry, high precision manipulation systems are especially needed for mass production of both micro and nano systems which consist of different component in respective scales. The transition from assembling and manipulating micro and nano entities manually to mass products with high quality is only attainable by automated assembly and manipulation systems. An example is the testing of integrated circuits which can be carried out by exchanging the manipulation tool by an electric probe. Furthermore, in medical research it is customary to pick up a single cell (human, plant, or animal), and carry it to another device which is used to further analyze the cell. Consequently, the cell of interest has to be separated from the other cells and picked up using the appropriate micro/nano tool. Hence it becomes absolutely necessary that the appropriate tool be used for specific micro or nano entity manipulation and assembly. In this research, we focus on developing micro tool for manipulating micro and nano entities in liquid environment using a micro fluidic end effector system with in-situ Polyvinylidene Fluoride (PVDF) sensing. The microfluidic end effector system consists of a DC micro-diaphragm pump and compressor, one region of flexible latex tube, a Polyvinylidene Fluoride (PVDF) sensor for in-situ measurement of micro drag force, and a micro pipette. The micro pipette of the novel microfluidic end effector system has an internal diameter (ID) smaller than 20mum used for microfluidic handling and deposition of micro and nano entities such as carbon nanotubes (CNT), DNA, and for droplet control. The novel microfluidic end effector system with force sensing can significantly improve the success rate for handling/depositing micro/nano entities in the case of carbon nanotubes between micro electrodes. The design, calibration, and experimental implementation of the novel microfluidic end effector is carried out in this research. The experimental results show the success rate for carbon nanotube(s) deposition between micro electrodes can reach close to 80%. Furthermore, carbon nanotubes are of particular interest because they are good candidates for many electronics and sensing applications. The interests in using carbon nanotubes to manufacture electronics and sensors have increased in recent years because of the increase need for making electronics smaller, and their excellent electrical and mechanical properties. These potentials can be achieved if CNTs with semiconducting and metallic band structure can be successfully deposited and separated. The use of dielectrophoresis (DEP) has been established as a course towards the efficient deposition and separation of metallic carbon nanotubes from semiconducting carbon nanotubes. For this reason, this research presents a new mathematical model for dielectrophoresis and electrorotation of carbon nanotubes. Simulation results are presented in this research to validate the developed model. The combination of both the micro robotic manipulation system and the atomic force microscopy (AFM) based nano-robotic system will provide a powerful tool for micro and nano manipulation. Additional applications of this research are endless considering the rapid development of micro and nano technologies.

Multiphase and multiscale approaches for modelling the injection of textured moulds

NASA Astrophysics Data System (ADS)

Nakhoul, Rebecca; Laure, Patrice; Silva, Luisa; Vincent, Michel

2016-10-01

Micro-injection moulding is frequently used for the mass production of devices in micro-medical technologies, micro-optics and micro-mechanics. This work focuses mainly on offering numerical tools to model the injection of micro-textured moulds. Such tools can predict the different filling scenarios of the micro-details and consequently offer optimal operating conditions (mould and melt temperatures, melt flow, stresses, etc.) to analyse the final part quality. To do so, a full Eulerian approach is used to model the injection of textured moulds at both the macroscopic and microscopic scales as usual industrial software cannot handle the filling of micro details. Since heat transfers with the mould are very relevant due to high cooling rates, the coupling between micro- and macro- simulations is primordial to insure a complete and accurate representation of textured mould injection.

Does the Size of a Company Make a Difference in the Prevalence of Exposure to Asthmagens and in the Use of Respiratory Protective Equipment?

PubMed

El-Zaemey, Sonia; Carey, Renee N; Darcey, Ellie; Reid, Alison; Rushton, Lesley; McElvenny, Damien M; Fritschi, Lin

2018-05-08

About half of all workers in high-income countries work in small companies. However, regulatory bodies and researchers predominantly work with large companies because they are more convenient to study and easier to reach. We aimed to estimate the prevalence of exposure to asthmagens and the use of respiratory protective equipment (RPE) by company size. This analysis used data from the Australian Work Exposures Study-Asthma, a telephone survey which investigated exposure to 27 asthmagen groups. Among 4844 respondents, 18.8, 19.9, 31.9, and 29.4% of workers reported working in micro (<5 employees), small (5-19 employees), medium (20-200 employees), and large (>200 employees) companies, respectively. Compared to workers in large companies, workers in micro, small, or medium companies had higher prevalence of exposure to most asthmagens and lesser use of RPE. Our results suggest that policy actions and regulatory measures should target micro/small companies in order to have the greatest effect.

Temporary shift in masked hearing thresholds in odontocetes after exposure to single underwater impulses from a seismic watergun.

PubMed

Finneran, James J; Schlundt, Carolyn E; Dear, Randall; Carder, Donald A; Ridgway, Sam H

2002-06-01

A behavioral response paradigm was used to measure masked underwater hearing thresholds in a bottlenose dolphin (Tursiops truncatus) and a white whale (Delphinapterus leucas) before and after exposure to single underwater impulsive sounds produced from a seismic watergun. Pre- and postexposure thresholds were compared to determine if a temporary shift in masked hearing thresholds (MTTS), defined as a 6-dB or larger increase in postexposure thresholds, occurred. Hearing thresholds were measured at 0.4, 4, and 30 kHz. MTTSs of 7 and 6 dB were observed in the white whale at 0.4 and 30 kHz, respectively, approximately 2 min following exposure to single impulses with peak pressures of 160 kPa, peak-to-peak pressures of 226 dB re 1 microPa, and total energy fluxes of 186 dB re 1 microPa2 x s. Thresholds returned to within 2 dB of the preexposure value approximately 4 min after exposure. No MTTS was observed in the dolphin at the highest exposure conditions: 207 kPa peak pressure, 228 dB re 1 microPa peak-to-peak pressure, and 188 dB re 1 microPa2 x s total energy flux.

Evolution of phenolic compounds and astringency during aging of red wine: effect of oxygen exposure before and after bottling.

PubMed

Gambuti, Angelita; Rinaldi, Alessandra; Ugliano, Maurizio; Moio, Luigi

2013-02-27

The aim of this study was to evaluate the effect of oxygen exposure of red wine, before (micro-oxygenation) and after (nano-oxygenation) bottling, on the phenolic composition and astringency of wine. The astringency was evaluated by sensory analysis and by a method based on the SDS-PAGE of salivary proteins after reaction of saliva with wine (SPI, saliva precipitation index). Micro-oxygenation caused a stabilization of color, but this effect disappeared after long aging. For the wine with the lower pH a decrease of wine astringency and SPI was observed 42 months after micro-oxygenation. Oxygen ingress through the closure postbottling was positively correlated with the decrease of SPI. Therefore, the astringency and reactivity of wines toward salivary proteins of a bottled red wine can be modulated by controlled oxygen exposure during aging. For both experiments the effect of oxygen exposure depended on wine composition.

Athletes’ Selected Micro-Activities on Turf Fields: Utilizing Extant Videography for Quantification of Events During Soccer, American Football, and Field Hockey Play

EPA Science Inventory

Concerns have been recently raised about the potential exposures of athletes to chemicals when playing on synthetic turf fields. Previous research has shown that micro-activities (i.e., hand-to mouth and skin-to-surface contacts) are important factors in people’s exposures to che...

Fabrication of micro-lens array on convex surface by meaning of micro-milling

NASA Astrophysics Data System (ADS)

Zhang, Peng; Du, Yunlong; Wang, Bo; Shan, Debin

2014-08-01

In order to develop the application of the micro-milling technology, and to fabricate ultra-precision optical surface with complex microstructure, in this paper, the primary experimental research on micro-milling complex microstructure array is carried out. A complex microstructure array surface with vary parameters is designed, and the mathematic model of the surface is set up and simulated. For the fabrication of the designed microstructure array surface, a micro three-axis ultra-precision milling machine tool is developed, aerostatic guideway drove directly by linear motor is adopted in order to guarantee the enough stiffness of the machine, and novel numerical control strategy with linear encoders of 5nm resolution used as the feedback of the control system is employed to ensure the extremely high motion control accuracy. With the help of CAD/CAM technology, convex micro lens array on convex spherical surface with different scales on material of polyvinyl chloride (PVC) and pure copper is fabricated using micro tungsten carbide ball end milling tool based on the ultra-precision micro-milling machine. Excellent nanometer-level micro-movement performance of the axis is proved by motion control experiment. The fabrication is nearly as the same as the design, the characteristic scale of the microstructure is less than 200μm and the accuracy is better than 1μm. It prove that ultra-precision micro-milling technology based on micro ultra-precision machine tool is a suitable and optional method for micro manufacture of microstructure array surface on different kinds of materials, and with the development of micro milling cutter, ultraprecision micro-milling complex microstructure surface will be achieved in future.

High-precision micro/nano-scale machining system

DOEpatents

Kapoor, Shiv G.; Bourne, Keith Allen; DeVor, Richard E.

2014-08-19

A high precision micro/nanoscale machining system. A multi-axis movement machine provides relative movement along multiple axes between a workpiece and a tool holder. A cutting tool is disposed on a flexible cantilever held by the tool holder, the tool holder being movable to provide at least two of the axes to set the angle and distance of the cutting tool relative to the workpiece. A feedback control system uses measurement of deflection of the cantilever during cutting to maintain a desired cantilever deflection and hence a desired load on the cutting tool.

Evaluation of polyurethane foam passive air sampler (PUF) as a tool for occupational PAH measurements.

PubMed

Strandberg, Bo; Julander, Anneli; Sjöström, Mattias; Lewné, Marie; Koca Akdeva, Hatice; Bigert, Carolina

2018-01-01

Routine monitoring of workplace exposure to polycyclic aromatic hydrocarbons (PAHs) is performed mainly via active sampling. However, active samplers have several drawbacks and, in some cases, may even be unusable. Polyurethane foam (PUF) as personal passive air samplers constitute good alternatives for PAH monitoring in occupational air (8 h). However, PUFs must be further tested to reliably yield detectable levels of PAHs in short exposure times (1-3 h) and under extreme occupational conditions. Therefore, we compared the personal exposure monitoring performance of a passive PUF sampler with that of an active air sampler and determined the corresponding uptake rates (Rs). These rates were then used to estimate the occupational exposure of firefighters and police forensic specialists to 32 PAHs. The work environments studied were heavily contaminated by PAHs with (for example) benzo(a)pyrene ranging from 0.2 to 56 ng m -3 , as measured via active sampling. We show that, even after short exposure times, PUF can reliably accumulate both gaseous and particle-bound PAHs. The Rs-values are almost independent of variables such as the concentration and the wind speed. Therefore, by using the Rs-values (2.0-20 m 3 day -1 ), the air concentrations can be estimated within a factor of two for gaseous PAHs and a factor of 10 for particulate PAHs. With very short sampling times (1 h), our method can serve as a (i) simple and user-friendly semi-quantitative screening tool for estimating and tracking point sources of PAH in micro-environments and (ii) complement to the traditional active pumping methods. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Exposure to crude oil micro-droplets causes reduced food uptake in copepods associated with alteration in their metabolic profiles.

PubMed

Hansen, Bjørn Henrik; Altin, Dag; Nordtug, Trond; Øverjordet, Ida Beathe; Olsen, Anders J; Krause, Dan; Størdal, Ingvild; Størseth, Trond R

2017-03-01

Acute oil spills and produced water discharges may cause exposure of filter-feeding pelagic organisms to micron-sized dispersed oil droplets. The dissolved oil components are expected to be the main driver for oil dispersion toxicity; however, very few studies have investigated the specific contribution of oil droplets to toxicity. In the present work, the contribution of oil micro-droplet toxicity in dispersions was isolated by comparing exposures to oil dispersions (water soluble fraction with droplets) to concurrent exposure to filtered dispersions (water-soluble fractions without droplets). Physical (coloration) and behavioral (feeding activity) as well as molecular (metabolite profiling) responses to oil exposures in the copepod Calanus finmarchicus were studied. At high dispersion concentrations (4.1-5.6mg oil/L), copepods displayed carapace discoloration and reduced swimming activity. Reduced feeding activity, measured as algae uptake, gut filling and fecal pellet production, was evident also for lower concentrations (0.08mg oil/L). Alterations in metabolic profiles were also observed following exposure to oil dispersions. The pattern of responses were similar between two comparable experiments with different oil types, suggesting responses to be non-oil type specific. Furthermore, oil micro-droplets appear to contribute to some of the observed effects triggering a starvation-type response, manifested as a reduction in metabolite (homarine, acetylcholine, creatine and lactate) concentrations in copepods. Our work clearly displays a relationship between crude oil micro-droplet exposure and reduced uptake of algae in copepods. Copyright © 2017 Elsevier B.V. All rights reserved.

[Effects of electromagnetic pulse on contents of amino acids in hippocampus of rats].

PubMed

Li, Yu-hong; Wang, De-wen; Peng, Rui-yun; Li, Zi-jian; Dong, Biao; Dong, Fang-ting; Liang, Yue-qin; Hu, Wen-hua

2003-10-01

To investigate the relationship between the changes of amino acids contents in hippocampus of rats and electromagnetic pulse (EMP) exposure. Rats were decapitated and hippocampus were removed after EMP (6 x 10(4) V/m, rise time 20 ns, pulse width 30 micro s, 5 pulses in 2 minutes) irradiation, and contents of amino acids were detected with high performance liquid chromatograpy (HPLC). The contents of aspartic acid (Asp) and glutamic acid (Glu) increased significantly 0, 3, 6 h after irradiation. The peak values of Asp [(17.25 +/- 1.63) pmol/ micro l] and Glu [(13.67 +/- 0.95) pmol/ micro l] were higher than those of control [(10.56 +/- 1.50), (6.94 +/- 1.10) pmol/ micro l respectively, P < 0.05]. Then both decreased gradually and reached the normal level 24 - 48 h after irradiation. The contents of glycine (Gly), taurine (Tau) and gamma-aminobutyric acid (GABA) also rose after exposure, the peak value of them [(4.51 +/- 0.60), (29.85 +/- 2.70), (5.14 +/- 0.73) pmol/ micro l respectively] were higher than those of control group [(2.18 +/- 0.31), (9.88 +/- 1.47), (2.84 +/- 0.67) pmol/ micro l, P < 0.05], then recovered 48 h after irradiation. The value of Glu/GABA increased immediately after exposure (3.45 +/- 0.25, P < 0.05), then decreased 24 h (1.62 +/- 0.23, P < 0.05) and recovered 48 h after exposure. The toxic effect of excess excitatory amino acids may be partly responsible for the early retardation (within 24 h) of learning of rats.

Swept Mechanism of Micro-Milling Tool Geometry Effect on Machined Oxygen Free High Conductivity Copper (OFHC) Surface Roughness

PubMed Central

Shi, Zhenyu; Liu, Zhanqiang; Li, Yuchao; Qiao, Yang

2017-01-01

Cutting tool geometry should be very much considered in micro-cutting because it has a significant effect on the topography and accuracy of the machined surface, particularly considering the uncut chip thickness is comparable to the cutting edge radius. The objective of this paper was to clarify the influence of the mechanism of the cutting tool geometry on the surface topography in the micro-milling process. Four different cutting tools including two two-fluted end milling tools with different helix angles of 15° and 30° cutting tools, as well as two three-fluted end milling tools with different helix angles of 15° and 30° were investigated by combining theoretical modeling analysis with experimental research. The tool geometry was mathematically modeled through coordinate translation and transformation to make all three cutting edges at the cutting tool tip into the same coordinate system. Swept mechanisms, minimum uncut chip thickness, and cutting tool run-out were considered on modeling surface roughness parameters (the height of surface roughness Rz and average surface roughness Ra) based on the established mathematical model. A set of cutting experiments was carried out using four different shaped cutting tools. It was found that the sweeping volume of the cutting tool increases with the decrease of both the cutting tool helix angle and the flute number. Great coarse machined surface roughness and more non-uniform surface topography are generated when the sweeping volume increases. The outcome of this research should bring about new methodologies for micro-end milling tool design and manufacturing. The machined surface roughness can be improved by appropriately selecting the tool geometrical parameters. PMID:28772479

Manufacture of high aspect ratio micro-pillar wall shear stress sensor arrays

NASA Astrophysics Data System (ADS)

Gnanamanickam, Ebenezer P.; Sullivan, John P.

2012-12-01

In the field of experimental fluid mechanics the measurement of unsteady, distributed wall shear stress has proved historically challenging. Recently, sensors based on an array of flexible micro-pillars have shown promise in carrying out such measurements. Similar sensors find use in other applications such as cellular mechanics. This work presents a manufacturing technique that can manufacture micro-pillar arrays of high aspect ratio. An electric discharge machine (EDM) is used to manufacture a micro-drilling tool. This micro-drilling tool is used to form holes in a wax sheet which acts as the mold for the micro-pillar array. Silicone rubber is cast in these molds to yield a micro-pillar array. Using this technique, micro-pillar arrays with a maximum aspect ratio of about 10 have been manufactured. Manufacturing issues encountered, steps to alleviate them and the potential of the process to manufacture similar micro-pillar arrays in a time-efficient manner are also discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jenny, Matthew J.; Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487; Aluru, Neelakanteswar

Although many drugs and environmental chemicals are teratogenic, the mechanisms by which most toxicants disrupt embryonic development are not well understood. MicroRNAs, single-stranded RNA molecules of ∼ 22 nt that regulate protein expression by inhibiting mRNA translation and promoting mRNA sequestration or degradation, are important regulators of a variety of cellular processes including embryonic development and cellular differentiation. Recent studies have demonstrated that exposure to xenobiotics can alter microRNA expression and contribute to the mechanisms by which environmental chemicals disrupt embryonic development. In this study we tested the hypothesis that developmental exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a well-known teratogen, alters microRNAmore » expression during zebrafish development. We exposed zebrafish embryos to DMSO (0.1%) or TCDD (5 nM) for 1 h at 30 hours post fertilization (hpf) and measured microRNA expression using several methods at 36 and 60 hpf. TCDD caused strong induction of CYP1A at 36 hpf (62-fold) and 60 hpf (135-fold) as determined by real-time RT-PCR, verifying the effectiveness of the exposure. MicroRNA expression profiles were determined using microarrays (Agilent and Exiqon), next-generation sequencing (SOLiD), and real-time RT-PCR. The two microarray platforms yielded results that were similar but not identical; both showed significant changes in expression of miR-451, 23a, 23b, 24 and 27e at 60 hpf. Multiple analyses were performed on the SOLiD sequences yielding a total of 16 microRNAs as differentially expressed by TCDD in zebrafish embryos. However, miR-27e was the only microRNA to be identified as differentially expressed by all three methods (both microarrays, SOLiD sequencing, and real-time RT-PCR). These results suggest that TCDD exposure causes modest changes in expression of microRNAs, including some (miR-451, 23a, 23b, 24 and 27e) that are critical for hematopoiesis and cardiovascular development. -- Highlights: ► Zebrafish embryos were exposed to TCDD at two different developmental timepoints. ► Compared different methods in detecting global changes in microRNA expression. ► TCDD caused significant changes in microRNA expression in zebrafish embryos. ► Differentially expressed microRNAs have roles related to TCDD-induced phenotypes.« less

Effect of micro-scale texturing on the cutting tool performance

NASA Astrophysics Data System (ADS)

Vasumathy, D.; Meena, Anil

2018-05-01

The present study is mainly focused on the cutting performance of the micro-scale textured carbide tools while turning AISI 304 austenitic stainless steel under dry cutting environment. The texture on the rake face of the carbide tools was fabricated by laser machining. The cutting performance of the textured tools was further compared with conventional tools in terms of cutting forces, tool wear, machined surface quality and chip curl radius. SEM and EDS analyses have been also performed to better understand the tool surface characteristics. Results show that the grooves help in breaking the tool-chip contact leading to a lesser tool-chip contact area which results in reduced iron (Fe) adhesion to the tool.

High speed micro scanner for 3D in-volume laser micro processing

NASA Astrophysics Data System (ADS)

Schaefer, D.; Gottmann, J.; Hermans, M.; Ortmann, J.; Kelbassa, I.

2013-03-01

Using an in-house developed micro scanner three-dimensional micro components and micro fluidic devices in fused silica are realized using the ISLE process (in-volume selective laser-induced etching). With the micro scanner system the potential of high average power femtosecond lasers (P > 100 W) is exploited by the fabrication of components with micrometer precision at scan speeds of several meters per second. A commercially available galvanometer scanner is combined with an acousto-optical and/or electro-optical beam deflector and translation stages. For focusing laser radiation high numerical aperture microscope objectives (NA > 0.3) are used generating a focal volume of a few cubic micrometers. After laser exposure the materials are chemically wet etched in aqueous solution. The laser-exposed material is etched whereas the unexposed material remains nearly unchanged. Using the described technique called ISLE the fabrication of three-dimensional micro components, micro holes, cuts and channels is possible with high average power femtosecond lasers resulting in a reduced processing time for exposure. By developing the high speed micro scanner up-scaling of the ISLE process is demonstrated. The fabricated components made out of glass can be applied in various markets like biological and medical diagnostics as well as in micro mechanics.

A vacuum microgripping tool with integrated vibration releasing capability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rong, Weibin; Fan, Zenghua, E-mail: zenghua-fan@163.com; Wang, Lefeng

2014-08-01

Pick-and-place of micro-objects is a basic task in various micromanipulation demands. Reliable releasing of micro-objects is usually disturbed due to strong scale effects. This paper focuses on a vacuum micro-gripper with vibration releasing functionality, which was designed and assembled for reliable micromanipulation tasks. Accordingly, a vibration releasing strategy of implementing a piezoelectric actuator on the vacuum microgripping tool is presented to address the releasing problem. The releasing mechanism was illustrated using a dynamic micro contact model. This model was developed via theoretical analysis, simulations and pull-off force measurement using atomic force microscopy. Micromanipulation experiments were conducted to verify the performancemore » of the vacuum micro-gripper. The results show that, with the assistance of the vibration releasing, the vacuum microgripping tool can achieve reliable release of micro-objects. A releasing location accuracy of 4.5±0.5 μm and a successful releasing rate of around 100% (which is based on 110 trials) were achieved for manipulating polystyrene microspheres with radius of 35–100 μm.« less

An evaluation of the impact of flooring types on exposures to fine and coarse particles within the residential micro-environment using CONTAM.

PubMed

Bramwell, Lisa; Qian, Jing; Howard-Reed, Cynthia; Mondal, Sumona; Ferro, Andrea R

2016-01-01

Typical resuspension activities within the home, such as walking, have been estimated to contribute up to 25% of personal exposures to PM10. Chamber studies have shown that for moderate walking intensities, flooring type can impact the rate at which particles are re-entrained into the air. For this study, the impact of residential flooring type on incremental average daily (24 h) time-averaged exposure was investigated. Distributions of incremental time-averaged daily exposures to fine and coarse PM while walking within the residential micro-environment were predicted using CONTAM, the multizone airflow and contaminant transport program of the National Institute of Standards and Technology. Knowledge of when and where a person was walking was determined by randomly selecting 490 daily diaries from the EPA's consolidated human activity database (CHAD). On the basis of the results of this study, residential flooring type can significantly impact incremental time-averaged daily exposures to coarse and fine particles (α=0.05, P<0.05, N=490, Kruskal-Wallis test) with high-density cut pile carpeting resulting in the highest exposures. From this study, resuspension from walking within the residential micro-environment contributed 6-72% of time-averaged daily exposures to PM10.

The micro conical system: Lessons learned from a successful EVA/robot-compatible mechanism

NASA Technical Reports Server (NTRS)

Gittleman, Mark; Johnston, Alistair

1996-01-01

The Micro Conical System (MCS) is a three-part, multi-purpose mechanical interface system used for acquiring and manipulating masses on-orbit by either extravehicular activity (EVA) or telerobotic means. The three components of the system are the micro conical fitting (MCF), the EVA micro tool (EMCT), and the Robot Micro Conical Tool (RMCT). The MCS was developed and refined over a four-year period. This period culminated with the delivery of 358 Class 1 and Class 2 micro conical fittings for the International Space Station and with its first use in space to handle a 1272 kg (2800 lbm) Spartan satellite (11000 times greater than the MCF mass) during an EVA aboard STS-63 in February, 1995. The micro conical system is the first successful EVA/robot-compatible mechanism to be demonstrated in the external environment aboard the U.S. Space Shuttle.

High performance cutting using micro-textured tools and low pressure jet coolant

NASA Astrophysics Data System (ADS)

Obikawa, Toshiyuki; Nakatsukasa, Ryuta; Hayashi, Mamoru; Ohno, Tatsumi

2018-05-01

Tool inserts with different kinds of microtexture on the flank face were fabricated by laser irradiation for promoting the heat transfer from the tool face to the coolant. In addition to the micro-textured tools, jet coolant was applied to the tool tip from the side of the flank face, but under low-pressure conditions, to make Reynolds number of coolant as high as possible in the wedge shape zone between the tool flank and machined surface. First, the effect of jet coolant on the flank wear evolution was investigated using a tool without microtexture. The jet coolant showed an excellent improvement of the tool life in machining stainless steel SUS304 at higher cutting speeds. It was found that both the flow rate and velocity of jet coolant were indispensable to high performance cutting. Next, the effect of microtexture on the flank wear evolution was investigated using jet coolant. Three types of micro grooves extended tool life largely compared to the tool without microtexture. It was found that the depth of groove was one of important parameters affecting the tool life extension. As a result, the tool life was extended by more than l00 % using the microtextured tools and jet coolant compared to machining using flood coolant and a tool without microtexture.

Design requirements for a stand alone EUV interferometer

NASA Astrophysics Data System (ADS)

Michallon, Ph.; Constancias, C.; Lagrange, A.; Dalzotto, B.

2008-03-01

EUV lithography is expected to be inserted for the 32/22 nm nodes with possible extension below. EUV resist availability remains one of the main issues to be resolved. There is an urgent need to provide suitable tools to accelerate resist development and to achieve resolution, LER and sensitivity specifications simultaneously. An interferometer lithography tool offers advantages regarding conventional EUV exposure tool. It allows the evaluation of resists, free from the deficiencies of optics and mask which are limiting the achieved resolution. Traditionally, a dedicated beam line from a synchrotron, with limited access, is used as a light source in EUV interference lithography. This paper identifies the technology locks to develop a stand alone EUV interferometer using a compact EUV source. It will describe the theoretical solutions adopted and especially look at the feasibility according to available technologies. EUV sources available on the market have been evaluated in terms of power level, source size, spatial coherency, dose uniformity, accuracy, stability and reproducibility. According to the EUV source characteristics, several optic designs were studied (simple or double gratings). For each of these solutions, the source and collimation optic specifications have been determined. To reduce the exposure time, a new grating technology will also be presented allowing to significantly increasing the transmission system efficiency. The optical grating designs were studied to allow multi-pitch resolution print on the same exposure without any focus adjustment. Finally micro mechanical system supporting the gratings was studied integrating the issues due to vacuum environment, alignment capability, motion precision, automation and metrology to ensure the needed placement control between gratings and wafer. A similar study was carried out for the collimation-optics mechanical support which depends on the source characteristics.

Investigation of the interaction dynamics of a pair of laser-induced bubbles generated at the same time through double-exposure strobe method and numerical simulations

NASA Astrophysics Data System (ADS)

Han, Bing; Liu, Liu; Ni, Xiao-Wu

2017-08-01

In order to understand the interaction dynamics of a pair of laser-induced bubbles, a double-exposure strobe photography experimental setup is build up to study the temporal evolution of the bubble pairs and to measure the transient bubble-interface moving speed. The interaction mechanisms of the bubble pairs are discussed together with the numerical results obtained through OpenFOAM. It is shown that the direction and the velocity of the jetting could be controlled by the relative size and the relative initiation distance of the bubble pair, when the bubbles are generated at the same time, i.e., in-phase. The liquid jet is considered to be a penetrating jet. The jet is originated from the smaller bubble and clearly protruding outside of the bigger bubble. The parameter space of the relative size and the initiation distance of the bubble pair allowing the formation of the penetrating jet are very narrow. It is concluded that the liquid jet induced by the bubble interactions resulted from the collapse and the rebound of the smaller bubble nearby the bigger bubble. This is defined as the "catapult effect." Such a directional liquid transportation is a promising tool as a micro-injector or a micro-pump. The investigation results could be also supplementary to the understandings of the bubble dynamics.

Background radiation: natural and man-made.

PubMed

Thorne, M C

2003-03-01

A brief overview and comparison is given of dose rates arising from natural background radiation and the fallout from atmospheric testing of nuclear weapons. Although there are considerable spatial variations in exposure to natural background radiation, it is useful to give estimates of worldwide average overall exposures from the various components of that background. Cosmic-ray secondaries of low linear energy transfer (LET), mainly muons and photons, deliver about 280 microSv a(-1). Cosmic-ray neutrons deliver about another 100 microSv a(-1). These low- and high-LET exposures are relatively uniform to the whole body. The effective dose rate from cosmogenic radionuclides is dominated by the contribution of 12 microSv a(-1) from 14C. This is due to relatively uniform irradiation of all organs and tissues from low-energy beta particles. Primordial radionuclides and their progeny (principally the 238U and 232Th series, and 40K) contribute about 480 microSv a(-1) of effective dose by external irradiation. This is relatively uniform photon irradiation of the whole body. Internally incorporated 40K contributes a further 165 microSv a(-1) of effective dose in adults, mainly from beta particles, but with a significant gamma component. Equivalent doses from 40K are somewhat higher in muscle than other soft tissues, but the distinction is less than a factor of three. Uranium and thorium series radionuclides give rise to an average effective dose rate of around 120 microSv a(-1). This includes a major alpha particle component, and exposures of radiosensitive tissues in lung, liver, kidney and the skeleton are recognised as important contributors to effective dose. Overall, these various sources give a worldwide average effective dose rate of about 1160 microSv a(-1). Exposure to 222Rn, 220Rn and their short-lived progeny has to be considered separately. This is very variable both within and between countries. For 222Rn and its progeny, a worldwide average effective dose rate is about 1105 microSv a(-1). For 220Rn and its progeny, the corresponding value is 91 microSv a(-1). In both cases, the effective dose is mainly due to a particle irradiation of the bronchial tissues of the lungs. Overall, the worldwide average effective dose rate from natural background is about 2400 microSv a(-1) or 2.4 mSv a(-1). For comparison, worldwide average effective dose rates from weapons fallout peaked at 113 microSv a(-1) (about 5% of natural background) in 1963 and have since fallen to about 5.5 microSv a(-1) (about 0.2% of natural background). These values perhaps serve to emphasise that even gross insults to the natural environment from anthropogenic releases of radioactive materials are likely to be of limited significance when set in the context of the ambient radioactive environment within which all organisms, including humans, have developed.

A machine vision system for micro-EDM based on linux

NASA Astrophysics Data System (ADS)

Guo, Rui; Zhao, Wansheng; Li, Gang; Li, Zhiyong; Zhang, Yong

2006-11-01

Due to the high precision and good surface quality that it can give, Electrical Discharge Machining (EDM) is potentially an important process for the fabrication of micro-tools and micro-components. However, a number of issues remain unsolved before micro-EDM becomes a reliable process with repeatable results. To deal with the difficulties in micro electrodes on-line fabrication and tool wear compensation, a micro-EDM machine vision system is developed with a Charge Coupled Device (CCD) camera, with an optical resolution of 1.61μm and an overall magnification of 113~729. Based on the Linux operating system, an image capturing program is developed with the V4L2 API, and an image processing program is exploited by using OpenCV. The contour of micro electrodes can be extracted by means of the Canny edge detector. Through the system calibration, the micro electrodes diameter can be measured on-line. Experiments have been carried out to prove its performance, and the reasons of measurement error are also analyzed.

Inhibition of ATPase activity in rat synaptic plasma membranes by simultaneous exposure to metals.

PubMed

Carfagna, M A; Ponsler, G D; Muhoberac, B B

1996-03-08

Inhibition of Na+/K+-ATPase and Mg2+-ATPase activities by in vitro exposure to Cd2+, Pb2+ and Mn2+ was investigated in rat brain synaptic plasma membranes (SPMs). Cd2+ and Pb2+ produced a larger maximal inhibition of Na+/K+-ATPase than of Mg2+-ATPase activity. Metal concentrations causing 50% inhibition of Na+/K+-ATPase activity (IC50 values) were Cd2+ (0.6 microM) < Pb2+ (2.1 microM) < Mn2+ (approximately 3 mM), and the former two metals were substantially more potent in inhibiting SPM versus synaptosomal Na+/K+-ATPase. Dixon plots of SPM data indicated that equilibrium binding of metals occurs at sites causing enzyme inhibition. In addition, IC50 values for SPM K+-dependent p-nitrophenylphosphatase inhibition followed the same order and were Cd2+ (0.4 microM) < Pb2+ (1.2 microM) < Mn2+ (300 microM). Simultaneous exposure to the combinations Cd2+/Mn2+ or Pb2+/Mn2+ inhibited SPM Na+/K+-ATPase activity synergistically (i.e., greater than the sum of the metal-induced inhibitions assayed separately), while Cd2+/Pb2+ caused additive inhibition. Simultaneous exposure to Cd2+/Pb2+ antagonistically inhibited Mg2+-ATPase activity while Cd2+/Mn2+ or Pb2+/Mn2+ additively inhibited Mg2+-ATPase activity at low Mn2+ concentrations, but inhibited antagonistically at higher concentrations. The similar IC50 values for Cd2+ and Pb2+ versus Mn2+ inhibition of Na+/K+-ATPase and the pattern of inhibition/activation upon exposure to two metals simultaneously support similar modes of interaction of Cd2+ and Pb2+ with this enzyme, in agreement with their chemical reactivities.

Arsenic in drinking water in the Los Altos de Jalisco region of Mexico.

PubMed

Hurtado-Jiménez, Roberto; Gardea-Torresdey, Jorge L

2006-10-01

To establish the degree of contamination by arsenic in drinking water in the Los Altos de Jalisco (LAJ) region of west-central Mexico, and to estimate the levels of exposure that residents of the area face. Total arsenic concentration (the sum of all arsenic forms, organic and inorganic) was determined for 129 public water wells in 17 municipal capitals (cabeceras municipales) of the LAJ region, using inductively coupled plasma-optical emission spectroscopy. For most of the wells, water samples were taken in both November 2002 and October 2003. The levels of exposure to arsenic were estimated for babies (10 kg), children (20 kg), and adults (70 kg). Mean concentrations of arsenic higher than the Mexican national guideline value of 25 micro g/L were found in 44 (34%) of the 129 wells. The mean concentration of total arsenic for the 129 wells ranged from 14.7 micro g/L to 101.9 micro g/L. The highest concentrations were found in well water samples collected in the cities of Mexticacán (262.9 micro g/L), Teocaltiche (157.7 micro g/L), and San Juan de los Lagos (113.8 micro g/L). Considering the global mean concentration for all the wells in each of the 17 cities, the mean concentration of arsenic exceeded the Mexican guideline value in 7 of the cities. However, the global mean concentration in all 17 cities was higher than the World Health Organization guideline value of 10 micro g/L for arsenic. The range of the estimated exposure doses to arsenic in drinking water was 1.1-7.6 micro g/kg/d for babies, 0.7-5.1 micro g/kg/d for children, and 0.4-2.7 micro g/kg/d for adults. At the exposure doses estimated in the LAJ region, the potential health effects from chronic arsenic ingestion include skin diseases, gastrointestinal effects, neurological damage, cardiovascular problems, and hematological effects. While all the residents may not be affected, an important fraction of the total population of the LAJ region is under potential health risk due to the ingestion of high levels of arsenic. Epidemiological studies to determine the arsenic levels in the blood, hair, and nails of humans should be conducted in the LAJ region to help assess the relationship between the prevalence of health problems and the chronic ingestion of arsenic.

Bioinformatics resource manager v2.3: an integrated software environment for systems biology with microRNA and cross-species analysis tools

PubMed Central

2012-01-01

Background MicroRNAs (miRNAs) are noncoding RNAs that direct post-transcriptional regulation of protein coding genes. Recent studies have shown miRNAs are important for controlling many biological processes, including nervous system development, and are highly conserved across species. Given their importance, computational tools are necessary for analysis, interpretation and integration of high-throughput (HTP) miRNA data in an increasing number of model species. The Bioinformatics Resource Manager (BRM) v2.3 is a software environment for data management, mining, integration and functional annotation of HTP biological data. In this study, we report recent updates to BRM for miRNA data analysis and cross-species comparisons across datasets. Results BRM v2.3 has the capability to query predicted miRNA targets from multiple databases, retrieve potential regulatory miRNAs for known genes, integrate experimentally derived miRNA and mRNA datasets, perform ortholog mapping across species, and retrieve annotation and cross-reference identifiers for an expanded number of species. Here we use BRM to show that developmental exposure of zebrafish to 30 uM nicotine from 6–48 hours post fertilization (hpf) results in behavioral hyperactivity in larval zebrafish and alteration of putative miRNA gene targets in whole embryos at developmental stages that encompass early neurogenesis. We show typical workflows for using BRM to integrate experimental zebrafish miRNA and mRNA microarray datasets with example retrievals for zebrafish, including pathway annotation and mapping to human ortholog. Functional analysis of differentially regulated (p<0.05) gene targets in BRM indicates that nicotine exposure disrupts genes involved in neurogenesis, possibly through misregulation of nicotine-sensitive miRNAs. Conclusions BRM provides the ability to mine complex data for identification of candidate miRNAs or pathways that drive phenotypic outcome and, therefore, is a useful hypothesis generation tool for systems biology. The miRNA workflow in BRM allows for efficient processing of multiple miRNA and mRNA datasets in a single software environment with the added capability to interact with public data sources and visual analytic tools for HTP data analysis at a systems level. BRM is developed using Java™ and other open-source technologies for free distribution (http://www.sysbio.org/dataresources/brm.stm). PMID:23174015

GSM base stations: short-term effects on well-being.

PubMed

Augner, Christoph; Florian, Matthias; Pauser, Gernot; Oberfeld, Gerd; Hacker, Gerhard W

2009-01-01

The purpose of this study was to examine the effects of short-term GSM (Global System for Mobile Communications) cellular phone base station RF-EMF (radiofrequency electromagnetic fields) exposure on psychological symptoms (good mood, alertness, calmness) as measured by a standardized well-being questionnaire. Fifty-seven participants were selected and randomly assigned to one of three different exposure scenarios. Each of those scenarios subjected participants to five 50-min exposure sessions, with only the first four relevant for the study of psychological symptoms. Three exposure levels were created by shielding devices in a field laboratory, which could be installed or removed during the breaks between sessions such that double-blinded conditions prevailed. The overall median power flux densities were 5.2 microW/m(2) during "low," 153.6 microW/m(2) during "medium," and 2126.8 microW/m(2) during "high" exposure sessions. For scenario HM and MH, the first and third sessions were "low" exposure. The second session was "high" and the fourth was "medium" in scenario HM; and vice versa for scenario MH. Scenario LL had four successive "low" exposure sessions constituting the reference condition. Participants in scenarios HM and MH (high and medium exposure) were significantly calmer during those sessions than participants in scenario LL (low exposure throughout) (P = 0.042). However, no significant differences between exposure scenarios in the "good mood" or "alertness" factors were obtained. We conclude that short-term exposure to GSM base station signals may have an impact on well-being by reducing psychological arousal. (c) 2008 Wiley-Liss, Inc.

Geometry and surface damage in micro electrical discharge machining of micro-holes

NASA Astrophysics Data System (ADS)

Ekmekci, Bülent; Sayar, Atakan; Tecelli Öpöz, Tahsin; Erden, Abdulkadir

2009-10-01

Geometry and subsurface damage of blind micro-holes produced by micro electrical discharge machining (micro-EDM) is investigated experimentally to explore the relational dependence with respect to pulse energy. For this purpose, micro-holes are machined with various pulse energies on plastic mold steel samples using a tungsten carbide tool electrode and a hydrocarbon-based dielectric liquid. Variations in the micro-hole geometry, micro-hole depth and over-cut in micro-hole diameter are measured. Then, unconventional etching agents are applied on the cross sections to examine micro structural alterations within the substrate. It is observed that the heat-damaged segment is composed of three distinctive layers, which have relatively high thicknesses and vary noticeably with respect to the drilling depth. Crack formation is identified on some sections of the micro-holes even by utilizing low pulse energies during machining. It is concluded that the cracking mechanism is different from cracks encountered on the surfaces when machining is performed by using the conventional EDM process. Moreover, an electrically conductive bridge between work material and debris particles is possible at the end tip during machining which leads to electric discharges between the piled segments of debris particles and the tool electrode during discharging.

A novel diamond micro-/nano-machining process for the generation of hierarchical micro-/nano-structures

NASA Astrophysics Data System (ADS)

Zhu, Zhiwei; To, Suet; Ehmann, Kornel F.; Xiao, Gaobo; Zhu, Wule

2016-03-01

A new mechanical micro-/nano-machining process that combines rotary spatial vibrations (RSV) of a diamond tool and the servo motions of the workpiece is proposed and applied for the generation of multi-tier hierarchical micro-/nano-structures. In the proposed micro-/nano-machining system, the servo motion, as the primary cutting motion generated by a slow-tool-servo, is adopted for the fine generation of the primary surfaces with complex shapes. The RSV, as the tertiary cutting operation, is superimposed on the secondary fundamental rotary cutting motion to construct secondary nano-structures on the primary surface. Since the RSV system generally works at much higher frequencies and motion resolution than the primary and secondary motions, it leads to an inherent hierarchical cutting architecture. To investigate the machining performance, complex micro-/nano-structures were generated and explored by both numerical simulations and actual cutting tests. Rotary vibrations of the diamond tool at a constant rotational distance offer an inherent constant cutting velocity, leading to the ability for the generation of homogeneous micro-/nano-structures with fixed amplitudes and frequencies of the vibrations, even over large-scale surfaces. Furthermore, by deliberately combining the non-resonant three-axial vibrations and the servo motion, the generation of a variety of micro-/nano-structures with complex shapes and with flexibly tunable feature sizes can be achieved.

SurvMicro: assessment of miRNA-based prognostic signatures for cancer clinical outcomes by multivariate survival analysis.

PubMed

Aguirre-Gamboa, Raul; Trevino, Victor

2014-06-01

MicroRNAs (miRNAs) play a key role in post-transcriptional regulation of mRNA levels. Their function in cancer has been studied by high-throughput methods generating valuable sources of public information. Thus, miRNA signatures predicting cancer clinical outcomes are emerging. An important step to propose miRNA-based biomarkers before clinical validation is their evaluation in independent cohorts. Although it can be carried out using public data, such task is time-consuming and requires a specialized analysis. Therefore, to aid and simplify the evaluation of prognostic miRNA signatures in cancer, we developed SurvMicro, a free and easy-to-use web tool that assesses miRNA signatures from publicly available miRNA profiles using multivariate survival analysis. SurvMicro is composed of a wide and updated database of >40 cohorts in different tissues and a web tool where survival analysis can be done in minutes. We presented evaluations to portray the straightforward functionality of SurvMicro in liver and lung cancer. To our knowledge, SurvMicro is the only bioinformatic tool that aids the evaluation of multivariate prognostic miRNA signatures in cancer. SurvMicro and its tutorial are freely available at http://bioinformatica.mty.itesm.mx/SurvMicro. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Occupational exposure to magnetic fields in relation to mortality from brain cancer among electricity generation and transmission workers.

PubMed Central

Harrington, J M; McBride, D I; Sorahan, T; Paddle, G M; van Tongeren, M

1997-01-01

OBJECTIVE: To investigate whether the risks of mortality from brain cancer are related to occupational exposure to magnetic fields. METHODS: A total of 112 cases of primary brain cancer (1972-91) were identified from a cohort of 84,018 male and female employees of the (then) Central Electricity Generating Board and its privatised successor companies. Individual cumulative occupational exposures to magnetic fields were estimated by linking available computerised job history data with magnetic field measurements collected over 675 person-workshifts. Estimated exposure histories of the case workers were compared with those of 654 control workers drawn from the cohort (nested case-control study), by means of conditional logistic regression. RESULTS: For exposure assessments based on arithmetic means, the risk of mortality from brain cancer for subjects with an estimated cumulative exposure to magnetic fields of 5.4-13.4 microT.y v subjects with lower exposures (0.0-5.3 microT.y) was 1.04 (95% confidence interval (95% CI) 0.60 to 1.80). The corresponding relative risk in subjects with higher exposures (> or = 13.5 microT.y) was 0.95 (95% CI 0.54 to 1.69). There was no indication of a positive trend for cumulative exposure and risk of mortality from brain cancer either when the analysis used exposure assessments based on geometric means or when the analysis was restricted to exposures received within five years of the case diagnosis (or corresponding period for controls). CONCLUSIONS: Although the exposure categorisation was based solely on recent observations, the study findings do not support the hypothesis that the risk of brain cancer is associated with occupational exposure to magnetic fields. PMID:9072027

Micro-Vibration Performance Prediction of SEPTA24 Using SMeSim (RUAG Space Mechanism Simulator Tool)

NASA Astrophysics Data System (ADS)

Omiciuolo, Manolo; Lang, Andreas; Wismer, Stefan; Barth, Stephan; Szekely, Gerhard

2013-09-01

Scientific space missions are currently challenging the performances of their payloads. The performances can be dramatically restricted by micro-vibration loads generated by any moving parts of the satellites, thus by Solar Array Drive Assemblies too. Micro-vibration prediction of SADAs is therefore very important to support their design and optimization in the early stages of a programme. The Space Mechanism Simulator (SMeSim) tool, developed by RUAG, enhances the capability of analysing the micro-vibration emissivity of a Solar Array Drive Assembly (SADA) under a specified set of boundary conditions. The tool is developed in the Matlab/Simulink® environment throughout a library of blocks simulating the different components a SADA is made of. The modular architecture of the blocks, assembled by the user, and the set up of the boundary conditions allow time-domain and frequency-domain analyses of a rigid multi-body model with concentrated flexibilities and coupled- electronic control of the mechanism. SMeSim is used to model the SEPTA24 Solar Array Drive Mechanism and predict its micro-vibration emissivity. SMeSim and the return of experience earned throughout its development and use can now support activities like verification by analysis of micro-vibration emissivity requirements and/or design optimization to minimize the micro- vibration emissivity of a SADA.

Optimization of Cvd Diamond Coating Type on Micro Drills in Pcb Machining

NASA Astrophysics Data System (ADS)

Lei, X. L.; He, Y.; Sun, F. H.

2016-12-01

The demand for better tools for machining printed circuit boards (PCBs) is increasing due to the extensive usage of these boards in digital electronic products. This paper is aimed at optimizing coating type on micro drills in order to extend their lifetime in PCB machining. First, the tribotests involving micro crystalline diamond (MCD), nano crystalline diamond (NCD) and bare tungsten carbide (WC-Co) against PCBs show that NCD-PCB tribopair exhibits the lowest friction coefficient (0.35) due to the unique nano structure and low surface roughness of NCD films. Thereafter, the dry machining performance of the MCD- and NCD-coated micro drills on PCBs is systematically studied, using diamond-like coating (DLC) and TiAlN-coated micro drills as comparison. The experiments show that the working lives of these micro drills can be ranked as: NCD>TiAlN>DLC>MCD>bare WC-Co. The superior cutting performance of NCD-coated micro drills in terms of the lowest flank wear growth rate, no tool degradation (e.g. chipping, tool tipping) appearance, the best hole quality as well as the lowest feed force may come from the excellent wear resistance, lower friction coefficient against PCB as well as the high adhesive strength on the underneath substrate of NCD films.

X-ray imaging with sub-micron resolution using large-area photon counting detectors Timepix

NASA Astrophysics Data System (ADS)

Dudak, J.; Karch, J.; Holcova, K.; Zemlicka, J.

2017-12-01

As X-ray micro-CT became a popular tool for scientific purposes a number of commercially available CT systems have emerged on the market. Micro-CT systems have, therefore, become widely accessible and the number of research laboratories using them constantly increases. However, even when CT scans with spatial resolution of several micrometers can be performed routinely, data acquisition with sub-micron precision remains a complicated task. Issues come mostly from prolongation of the scan time inevitably connected with the use of nano-focus X-ray sources. Long exposure time increases the noise level in the CT projections. Furthermore, considering the sub-micron resolution even effects like source-spot drift, rotation stage wobble or thermal expansion become significant and can negatively affect the data. The use of dark-current free photon counting detectors as X-ray cameras for such applications can limit the issue of increased image noise in the data, however the mechanical stability of the whole system still remains a problem and has to be considered. In this work we evaluate the performance of a micro-CT system equipped with nano-focus X-ray tube and a large area photon counting detector Timepix for scans with effective pixel size bellow one micrometer.

Fabrication of a micro-fluid gathering tool for the gastrointestinal juice sampling function of a versatile capsular endoscope.

PubMed

Koo, Kyo-In; Lee, Sangmin; Cho, Dong-il Dan

2011-01-01

This paper presents a micro-fluid gathering tool for a versatile capsular endoscope that employs a solid chemical propellant, azobisisobutyronitrile (AIBN). The proposed tool consists of a micro-heater, an AIBN matrix, a Venturi tube, a reservoir, an inlet, and an outlet. The micro-heater heats the AIBN matrix to be decomposed into by-products and nitrogen gas. This nitrogen gas generates negative pressure passing through the Venturi tube. The generated negative pressure inhales a target fluid from around the inlet into the reservoir. All the parts are designed to be embedded inside a cylindrical shape with a diameter of 17 mm and a height of 2.3 mm in order to integrate it into a versatile developmental capsular endoscope without any scaledown. Two sets of the proposed tools are fabricated and tested: one is made of polydimethylsiloxane (PDMS) and the other is made of polymethylmethacrylate (PMMA). In performance comparisons, the PDMS gathering tool can withstand a stronger pulling force, and the PMMA gathering tool requires a less negative pressure for inhaling the same target fluid. Due to the instant and full activation of the thin AIBN matrix, both types of gathering tool show analogous performance in the sample gathering evaluation. The gathered volume is approximately 1.57 μL using approximately 25.4 μL of AIBN compound.

Fabrication of a Micro-Fluid Gathering Tool for the Gastrointestinal Juice Sampling Function of a Versatile Capsular Endoscope

PubMed Central

Koo, Kyo-in; Lee, Sangmin; Cho, Dong-il Dan

2011-01-01

This paper presents a micro-fluid gathering tool for a versatile capsular endoscope that employs a solid chemical propellant, azobisisobutyronitrile (AIBN). The proposed tool consists of a micro-heater, an AIBN matrix, a Venturi tube, a reservoir, an inlet, and an outlet. The micro-heater heats the AIBN matrix to be decomposed into by-products and nitrogen gas. This nitrogen gas generates negative pressure passing through the Venturi tube. The generated negative pressure inhales a target fluid from around the inlet into the reservoir. All the parts are designed to be embedded inside a cylindrical shape with a diameter of 17 mm and a height of 2.3 mm in order to integrate it into a versatile developmental capsular endoscope without any scaledown. Two sets of the proposed tools are fabricated and tested: one is made of polydimethylsiloxane (PDMS) and the other is made of polymethylmethacrylate (PMMA). In performance comparisons, the PDMS gathering tool can withstand a stronger pulling force, and the PMMA gathering tool requires a less negative pressure for inhaling the same target fluid. Due to the instant and full activation of the thin AIBN matrix, both types of gathering tool show analogous performance in the sample gathering evaluation. The gathered volume is approximately 1.57 μL using approximately 25.4 μL of AIBN compound. PMID:22163997

Micro-CT image-derived metrics quantify arterial wall distensibility reduction in a rat model of pulmonary hypertension

NASA Astrophysics Data System (ADS)

Johnson, Roger H.; Karau, Kelly L.; Molthen, Robert C.; Haworth, Steven T.; Dawson, Christopher A.

2000-04-01

We developed methods to quantify arterial structural and mechanical properties in excised rat lungs and applied them to investigate the distensibility decrease accompanying chronic hypoxia-induced pulmonary hypertension. Lungs of control and hypertensive (three weeks 11% O2) animals were excised and a contrast agent introduced before micro-CT imaging with a special purpose scanner. For each lung, four 3D image data sets were obtained, each at a different intra-arterial contrast agent pressure. Vessel segment diameters and lengths were measured at all levels in the arterial tree hierarchy, and these data used to generate features sensitive to distensibility changes. Results indicate that measurements obtained from 3D micro-CT images can be used to quantify vessel biomechanical properties in this rat model of pulmonary hypertension and that distensibility is reduced by exposure to chronic hypoxia. Mechanical properties can be assessed in a localized fashion and quantified in a spatially-resolved way or as a single parameter describing the tree as a whole. Micro-CT is a nondestructive way to rapidly assess structural and mechanical properties of arteries in small animal organs maintained in a physiological state. Quantitative features measured by this method may provide valuable insights into the mechanisms causing the elevated pressures in pulmonary hypertension of differing etiologies and should become increasingly valuable tools in the study of complex phenotypes in small-animal models of important diseases such as hypertension.

AVAILABLE MICRO-ACTIVITY DATA AND THEIR APPLICABILITY TO AGGREGATE EXPOSURE MODELING

EPA Science Inventory

Several human exposure models have been developed in recent years to address children's aggregate and cumulative exposures to pesticides under the Food Quality Protection Act of 1996. These models estimate children's exposures via all significant routes and pathways including ...

Mechanical and Electronic Approaches to Improve the Sensitivity of Microcantilever Sensors

PubMed Central

Mutyala, Madhu Santosh Ku; Bandhanadham, Deepika; Pan, Liu; Pendyala, Vijaya Rohini; Ji, Hai-Feng

2010-01-01

Advances in the field of Micro Electro Mechanical Systems (MEMS) and their uses now offer unique opportunities in the design of ultrasensitive analytical tools. The analytical community continues to search for cost-effective, reliable, and even portable analytical techniques that can give reliable and fast response results for a variety of chemicals and biomolecules. Microcantilevers (MCLs) have emerged as a unique platform for label-free biosensor or bioassay. Several electronic designs, including piezoresistive, piezoelectric, and capacitive approaches, have been applied to measure the bending or frequency change of the MCLs upon exposure to chemicals. This review summarizes mechanical, fabrication, and electronics approaches to increase the sensitivity of microcantilever (MCL) sensors. PMID:20975987

Servo scanning 3D micro EDM for array micro cavities using on-machine fabricated tool electrodes

NASA Astrophysics Data System (ADS)

Tong, Hao; Li, Yong; Zhang, Long

2018-02-01

Array micro cavities are useful in many fields including in micro molds, optical devices, biochips and so on. Array servo scanning micro electro discharge machining (EDM), using array micro electrodes with simple cross-sectional shape, has the advantage of machining complex 3D micro cavities in batches. In this paper, the machining errors caused by offline-fabricated array micro electrodes are analyzed in particular, and then a machining process of array servo scanning micro EDM is proposed by using on-machine fabricated array micro electrodes. The array micro electrodes are fabricated on-machine by combined procedures including wire electro discharge grinding, array reverse copying and electrode end trimming. Nine-array tool electrodes with Φ80 µm diameter and 600 µm length are obtained. Furthermore, the proposed process is verified by several machining experiments for achieving nine-array hexagonal micro cavities with top side length of 300 µm, bottom side length of 150 µm, and depth of 112 µm or 120 µm. In the experiments, a chip hump accumulates on the electrode tips like the built-up edge in mechanical machining under the conditions of brass workpieces, copper electrodes and the dielectric of deionized water. The accumulated hump can be avoided by replacing the water dielectric by an oil dielectric.

Variations of melatonin and stress hormones under extended shifts and radiofrequency electromagnetic radiation.

PubMed

Vangelova, Katia Koicheva; Israel, Mishel Salvador

2005-01-01

We studied the time-of-day variations in urinary levels of 6-sulphatoxy-melatonin and three stress hormones in operators working fast-rotating extended shifts under radiofrequency electromagnetic radiation (EMR). The excretion rate of the hormones was monitored by radioimmunoassay and spectrofluorimetry at 4-hour intervals in a group of 36 male operators comprising 12 broadcasting station operators, 12 TV station operators, and a control group of 12 satellite station operators. Measuring the time-weighted average (TWA) of EMR exposure revealed a high-level of exposure in broadcasting station operators (TWAmean= 3.10 microW/ cm2, TWAmax = 137.00 microW/cm2), a low-level in TV station operators (TWAmean = 1.89 microW/cm2, TWAmax = 5.24 microW/cm2), and a very low level in satellite station operators. The differences among the groups remained the same after confounding factors were taken into account. Radiofrequency EMR had no effect on the typical diurnal pattern of 6-sulphatoxymelatonin. High-level radiofrequency EMR exposure significantly increased the excretion rates of cortisol (p < 0.001), adrenaline (p = 0.028), and noradrenaline (p < 0.000), whereas changes under low-level exposure did not reach significance. The 24-hour excretion of cortisol and noradrenaline correlated with TWAmean and TWAmax. In conclusion, the excretion of 6-sulphatoxymelatonin retained a typical diurnal pattern under fast-rotating extended shifts and radiofrequency EMR, but showed an exposure-effect relation with stress hormones.

AFM surface imaging of AISI D2 tool steel machined by the EDM process

NASA Astrophysics Data System (ADS)

Guu, Y. H.

2005-04-01

The surface morphology, surface roughness and micro-crack of AISI D2 tool steel machined by the electrical discharge machining (EDM) process were analyzed by means of the atomic force microscopy (AFM) technique. Experimental results indicate that the surface texture after EDM is determined by the discharge energy during processing. An excellent machined finish can be obtained by setting the machine parameters at a low pulse energy. The surface roughness and the depth of the micro-cracks were proportional to the power input. Furthermore, the AFM application yielded information about the depth of the micro-cracks is particularly important in the post treatment of AISI D2 tool steel machined by EDM.

Circulating microRNAs in serum from cattle challenged with Bovine Viral Diarrhea Virus

USDA-ARS?s Scientific Manuscript database

Bovine viral diarrhea virus (BVDV) is an RNA virus that is often associated with respiratory disease in cattle. MicroRNAs have been proposed as indicators of exposure to respiratory pathogens. The objective of this study was to identify microRNAs in cattle that had been challenged with a non-cytopat...

Micro-CT Imaging of Denatured Chitin by Silver to Explore Honey Bee and Insect Pathologies

PubMed Central

Butzloff, Peter R.

2011-01-01

Background Chitin and cuticle coatings are important to the environmental and immune defense of honey bees and insect pollinators. Pesticides or environmental effects may target the biochemistry of insect chitin and cuticle coating. Denaturing of chitin involves a combination of deacetylation, intercalation, oxidation, Schweiger-peeling, and the formation of amine hydrochloride salt. The term “denatured chitin” calls attention to structural and property changes to the internal membranes and external carapace of organisms so that some properties affecting biological activities are diminished. Methodology/Principal Findings A case study was performed on honey bees using silver staining and microscopic computer-tomographic x-ray radiography (micro-CT). Silver nitrate formed counter-ion complexes with labile ammonium cations and reacted with amine hydrochloride. Silver was concentrated in the peritrophic membrane, on the abdomen, in the glossa, at intersegmental joints (tarsi), at wing attachments, and in tracheal air sacs. Imaged mono-esters and fatty acids from cuticle coating on external surfaces were apparently reduced by an alcohol pretreatment. Conclusions/Significance The technique provides 3-dimensional and sectional images of individual honey bees consistent with the chemistries of silver reaction and complex formation with denatured chitin. Environmental exposures and influences such as gaseous nitric oxide intercalant, trace oxidants such as ozone gas, oligosachharide salt conversion, exposure to acid rain, and chemical or biochemical denaturing by pesticides may be studied using this technique. Peritrophic membranes, which protect against food abrasion, microorganisms, and permit efficient digestion, were imaged. Apparent surface damage to the corneal lenses of compound eyes by dilute acid exposure consistent with chitin amine hydrochloride formation was imaged. The technique can contribute to existing insect pathology research, and may provide an additional tool for research on CCD. PMID:22110654

Transmitted irradiance through ceramics: effect on the mechanical properties of a luting resin cement.

PubMed

Ilie, Nicoleta

2017-05-01

The study aims to characterise the curing behaviour of a light-curing luting composite (Variolink® Aesthetic LC, Ivoclar Vivadent) polymerised at different exposure times (10 s, 20 s) through different ceramics (IPS Empress CAD and IPS e.max CAD, Ivoclar Vivadent) and ceramic thicknesses (no ceramic, 0.5, 1, 1.5 and 2 mm). Curing units' (Bluephase Style, Ivoclar Vivadent) variation in irradiance delivered up to 10-mm exposure distance as well as the incident and transmitted irradiance and radiant exposure up to 6-mm ceramic thickness were assessed on a laboratory-grade spectrometer. A total of 216 (18 groups, n = 12) thin and flat luting composite specimens of 500-μm thickness were prepared and stored after curing in a saturated vapour atmosphere for 24 h at 37 °C. Micro-mechanical properties (Vickers hardness, HV and indentation modulus, Y HU ) were determined by means of an automatic micro-hardness indenter. Within the study design, the radiant exposure received by the luting composite varied from 2.56 to 24.75 J/cm 2 , showing a high impact on the measured properties. Comparing the effect of the parameters exposure time, ceramic thickness and type, the highest influence on the micro-mechanical parameters was identified for exposure time, while this influence was stronger on HV (p < 0.001, η P 2  = 0.452) than on Y HU (p < 0.001, η P 2  = 0.178). The influence of ceramic type was significant but low (η P 2  = 0.161 on HV and 0.113 on Y HU ), while the influence of ceramic thickness was the lowest (η P 2  = 0.04 and 0.05, respectively). Slightly higher irradiance values were transmitted through Empress CAD up to a ceramic thickness of 3 mm (p < 0.001), while being comparable with e.max for thicker slices. Differences in translucency between ceramics were reflected in the micro-mechanical properties of the luting composite. The radiant exposure reaching the luting composite is determined by the incident irradiance, exposure time, ceramic type and ceramic thickness. At the analysed incident irradiance, exposure time was the most consistent parameter affecting the micro-mechanical properties of the luting composite, and this effect was strongly reflected in the more translucent ceramic Empress CAD. Within the curing conditions, an exposure time of 20 s is recommended.

Negative effects of microplastic exposure on growth and development of Crepidula onyx.

PubMed

Lo, Hau Kwan Abby; Chan, Kit Yu Karen

2018-02-01

Microplastics exposure could be detrimental to marine organisms especially under high concentrations. However, few studies have considered the multiphasic nature of marine invertebrates' life history and investigated the impact of experiencing microplastics during early development on post-metamorphic stages (legacy effect). Many planktonic larvae can feed selectively and it is unclear whether such selectivity could modulate the impact of algal food-sized microplastic. In this two-stage experiment, veligers of Crepidula onyx were first exposed to additions of algae-sized micro-polystyrene (micro-PS) beads at different concentrations, including ones that were comparable their algal diet. These additions were then either halted or continued after settlement. At environmentally relevant concentration (ten 2-μm microplastic beads ml -1 ), larval and juvenile C. onyx was not affected. At higher concentrations, these micro-PS fed larvae consumed a similar amount of algae compared to those in control but grew relatively slower than those in the control suggesting that ingestion and/or removal of microplastic was/were energetically costly. These larvae also settled earlier at a smaller size compared to the control, which could negatively affect post-settlement success. Juvenile C. onyx receiving continuous micro-PS addition had slower growth rates. Individuals only exposed to micro-PS during their larval stage continued to have slower growth rates than those in the control even if micro-PS had been absent in their surroundings for 65 days highlighting a legacy effect of microplastic exposure. Copyright © 2017 Elsevier Ltd. All rights reserved.

mESAdb: microRNA Expression and Sequence Analysis Database

PubMed Central

Kaya, Koray D.; Karakülah, Gökhan; Yakıcıer, Cengiz M.; Acar, Aybar C.; Konu, Özlen

2011-01-01

microRNA expression and sequence analysis database (http://konulab.fen.bilkent.edu.tr/mirna/) (mESAdb) is a regularly updated database for the multivariate analysis of sequences and expression of microRNAs from multiple taxa. mESAdb is modular and has a user interface implemented in PHP and JavaScript and coupled with statistical analysis and visualization packages written for the R language. The database primarily comprises mature microRNA sequences and their target data, along with selected human, mouse and zebrafish expression data sets. mESAdb analysis modules allow (i) mining of microRNA expression data sets for subsets of microRNAs selected manually or by motif; (ii) pair-wise multivariate analysis of expression data sets within and between taxa; and (iii) association of microRNA subsets with annotation databases, HUGE Navigator, KEGG and GO. The use of existing and customized R packages facilitates future addition of data sets and analysis tools. Furthermore, the ability to upload and analyze user-specified data sets makes mESAdb an interactive and expandable analysis tool for microRNA sequence and expression data. PMID:21177657

mESAdb: microRNA expression and sequence analysis database.

PubMed

Kaya, Koray D; Karakülah, Gökhan; Yakicier, Cengiz M; Acar, Aybar C; Konu, Ozlen

2011-01-01

microRNA expression and sequence analysis database (http://konulab.fen.bilkent.edu.tr/mirna/) (mESAdb) is a regularly updated database for the multivariate analysis of sequences and expression of microRNAs from multiple taxa. mESAdb is modular and has a user interface implemented in PHP and JavaScript and coupled with statistical analysis and visualization packages written for the R language. The database primarily comprises mature microRNA sequences and their target data, along with selected human, mouse and zebrafish expression data sets. mESAdb analysis modules allow (i) mining of microRNA expression data sets for subsets of microRNAs selected manually or by motif; (ii) pair-wise multivariate analysis of expression data sets within and between taxa; and (iii) association of microRNA subsets with annotation databases, HUGE Navigator, KEGG and GO. The use of existing and customized R packages facilitates future addition of data sets and analysis tools. Furthermore, the ability to upload and analyze user-specified data sets makes mESAdb an interactive and expandable analysis tool for microRNA sequence and expression data.

Smart Cutting Tools and Smart Machining: Development Approaches, and Their Implementation and Application Perspectives

NASA Astrophysics Data System (ADS)

Cheng, Kai; Niu, Zhi-Chao; Wang, Robin C.; Rakowski, Richard; Bateman, Richard

2017-09-01

Smart machining has tremendous potential and is becoming one of new generation high value precision manufacturing technologies in line with the advance of Industry 4.0 concepts. This paper presents some innovative design concepts and, in particular, the development of four types of smart cutting tools, including a force-based smart cutting tool, a temperature-based internally-cooled cutting tool, a fast tool servo (FTS) and smart collets for ultraprecision and micro manufacturing purposes. Implementation and application perspectives of these smart cutting tools are explored and discussed particularly for smart machining against a number of industrial application requirements. They are contamination-free machining, machining of tool-wear-prone Si-based infra-red devices and medical applications, high speed micro milling and micro drilling, etc. Furthermore, implementation techniques are presented focusing on: (a) plug-and-produce design principle and the associated smart control algorithms, (b) piezoelectric film and surface acoustic wave transducers to measure cutting forces in process, (c) critical cutting temperature control in real-time machining, (d) in-process calibration through machining trials, (e) FE-based design and analysis of smart cutting tools, and (f) application exemplars on adaptive smart machining.

Photoinduced toxicity of fluoranthene to northern leopard frogs (Rana pipiens)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Monson, P.D.; Call, D.J.; Cox, D.A.

1999-02-01

Rana pipiens larvae were exposed for 48 h in a flow-through system to clean water or five concentrations of the phototoxic polycyclic aromatic hydrocarbon (PAH) fluoranthene. Following this uptake period, the larvae were divided into four groups: one for immediate tissue residue analysis, a second for residue analysis following 48 h of depuration in clean water, and two for a 48-h exposure in clean water to ultraviolet (UV) light at two different levels. At the highest treatment, mean intensity was 8.12 {+-} 0.19 {times} 10{sup 2} {micro}W/cm{sup 2}, whereas at a lower treatment the UVA intensity was 4.45 {+-} 0.05more » {times} 10{sup 2} {micro}W/cm{sup 2}. Larval frogs bioaccumulated fluoranthene in direct proportion to the water exposure concentrations, with initial whole-body PAH concentrations of 1.48, 3.53, 4.85, 11.3, and 18.7 {micro}g/g at the five treatment levels. No mortality of the animals occurred during the 48-h uptake phase. When the frogs were placed in clean water, the fluoranthene was rapidly depurated, with up to 80% lost in 48 h. Exposure to UV light following fluoranthene exposure significantly enhanced toxicity of the PAH. Median time to death decreased as the product of UVA light intensity and fluoranthene body residue increased. For larval R. Pipiens, sufficient tissue residues of fluoranthene were bioaccumulated within 48 h, at water exposure concentrations in the range of 2 to 10 {micro}g/L, to be lethal when combined with a UVA exposure simulating a fraction of summertime, midday sunlight in northern latitudes.« less

A Vibrating Wire System For Quadrupole Fiducialization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolf, Zachary

2010-12-13

A vibrating wire system is being developed to fiducialize the quadrupoles between undulator segments in the LCLS. This note provides a detailed analysis of the system. The LCLS will have quadrupoles between the undulator segments to keep the electron beam focused. If the quadrupoles are not centered on the beam axis, the beam will receive transverse kicks, causing it to deviate from the undulator axis. Beam based alignment will be used to move the quadrupoles onto a straight line, but an initial, conventional alignment must place the quadrupole centers on a straight line to 100 {micro}m. In the fiducialization stepmore » of the initial alignment, the position of the center of the quadrupole is measured relative to tooling balls on the outside of the quadrupole. The alignment crews then use the tooling balls to place the magnet in the tunnel. The required error on the location of the quadrupole center relative to the tooling balls must be less than 25 {micro}m. In this note, we analyze a system under construction for the quadrupole fiducialization. The system uses the vibrating wire technique to position a wire onto the quadrupole magnetic axis. The wire position is then related to tooling balls using wire position detectors. The tooling balls on the wire position detectors are finally related to tooling balls on the quadrupole to perform the fiducialization. The total 25 {micro}m fiducialization error must be divided between these three steps. The wire must be positioned onto the quadrupole magnetic axis to within 10 {micro}m, the wire position must be measured relative to tooling balls on the wire position detectors to within 15 {micro}m, and tooling balls on the wire position detectors must be related to tooling balls on the quadrupole to within 10 {micro}m. The techniques used in these three steps will be discussed. The note begins by discussing various quadrupole fiducialization techniques used in the past and discusses why the vibrating wire technique is our method of choice. We then give an overview of the measurement system showing how the vibrating wire is positioned onto the quadrupole axis, how the wire position detectors locate the wire relative to tooling balls without touching the wire, and how the tooling ball positions are all measured. The novel feature of this system is the vibrating wire which we discuss in depth. We analyze the wire dynamics and calculate the expected sensitivity of the system. The note should be an aid in debugging the system by providing calculations to compare measurements to.« less

miRiaD: A Text Mining Tool for Detecting Associations of microRNAs with Diseases.

PubMed

Gupta, Samir; Ross, Karen E; Tudor, Catalina O; Wu, Cathy H; Schmidt, Carl J; Vijay-Shanker, K

2016-04-29

MicroRNAs are increasingly being appreciated as critical players in human diseases, and questions concerning the role of microRNAs arise in many areas of biomedical research. There are several manually curated databases of microRNA-disease associations gathered from the biomedical literature; however, it is difficult for curators of these databases to keep up with the explosion of publications in the microRNA-disease field. Moreover, automated literature mining tools that assist manual curation of microRNA-disease associations currently capture only one microRNA property (expression) in the context of one disease (cancer). Thus, there is a clear need to develop more sophisticated automated literature mining tools that capture a variety of microRNA properties and relations in the context of multiple diseases to provide researchers with fast access to the most recent published information and to streamline and accelerate manual curation. We have developed miRiaD (microRNAs in association with Disease), a text-mining tool that automatically extracts associations between microRNAs and diseases from the literature. These associations are often not directly linked, and the intermediate relations are often highly informative for the biomedical researcher. Thus, miRiaD extracts the miR-disease pairs together with an explanation for their association. We also developed a procedure that assigns scores to sentences, marking their informativeness, based on the microRNA-disease relation observed within the sentence. miRiaD was applied to the entire Medline corpus, identifying 8301 PMIDs with miR-disease associations. These abstracts and the miR-disease associations are available for browsing at http://biotm.cis.udel.edu/miRiaD . We evaluated the recall and precision of miRiaD with respect to information of high interest to public microRNA-disease database curators (expression and target gene associations), obtaining a recall of 88.46-90.78. When we expanded the evaluation to include sentences with a wide range of microRNA-disease information that may be of interest to biomedical researchers, miRiaD also performed very well with a F-score of 89.4. The informativeness ranking of sentences was evaluated in terms of nDCG (0.977) and correlation metrics (0.678-0.727) when compared to an annotator's ranked list. miRiaD, a high performance system that can capture a wide variety of microRNA-disease related information, extends beyond the scope of existing microRNA-disease resources. It can be incorporated into manual curation pipelines and serve as a resource for biomedical researchers interested in the role of microRNAs in disease. In our ongoing work we are developing an improved miRiaD web interface that will facilitate complex queries about microRNA-disease relationships, such as "In what diseases does microRNA regulation of apoptosis play a role?" or "Is there overlap in the sets of genes targeted by microRNAs in different types of dementia?"."

Coordinated dysregulation of mRNAs and microRNAs in the rat medial prefrontal cortex following a history of alcohol dependence

PubMed Central

Tapocik, Jenica D.; Solomon, Matthew; Flanigan, Meghan; Meinhardt, Marcus; Barbier, Estelle; Schank, Jesse; Schwandt, Melanie; Sommer, Wolfgang H.; Heilig, Markus

2012-01-01

Long-term changes in brain gene expression have been identified in alcohol dependence, but underlying mechanisms remain unknown. Here, we examined the potential role of microRNAs for persistent gene expression changes in the rat medial prefrontal cortex after a history of alcohol dependence. Two-bottle free-choice alcohol consumption increased following 7-week exposure to intermittent alcohol intoxication. A bioinformatic approach using microarray analysis, qPCR, bioinformatic analysis, and microRNA-mRNA integrative analysis identified expression patterns indicative of a disruption in synaptic processes and neuroplasticity. 41 rat-microRNAs and 165 mRNAs in the medial prefrontal cortex were significantly altered after chronic alcohol exposure. A subset of the microRNAs and mRNAs was confirmed by qPCR. Gene ontology categories of differential expression pointed to functional processes commonly associated with neurotransmission, neuroadaptation, and synaptic plasticity. microRNA-mRNA expression pairing identified 33 microRNAs putatively targeting 89 mRNAs suggesting transcriptional networks involved in axonal guidance and neurotransmitter signaling. Our results demonstrate a significant shift in microRNA expression patterns in the medial prefrontal cortex following a history of dependence. Due to their global regulation of multiple downstream target transcripts, microRNAs may play a pivotal role in the reorganization of synaptic connections and long term neuroadaptations in alcohol dependence. microRNA-mediated alterations of transcriptional networks may be involved in disrupted prefrontal control over alcohol-drinking observed in alcoholic patients. PMID:22614244

Cryopreservation of human insulin expressing cells macro-encapsulated in a durable therapeutic immunoisolating device theracyte.

PubMed

Yakhnenko, Ilya; Wong, Wallace K; Katkov, Igor I; Itkin-Ansari, Pamela

2012-01-01

Encapsulating insulin producing cells (INPCs) in an immunoisolation device have been shown to cure diabetes in rodents without the need for immunosuppression. However, micro-encapsulation in semi-solid gels raises longevity and safety concerns for future use of stem cell derived INPCs. We have focused on a durable and retrievable macro-encapsulation (> 10(6) cells) device (TheraCyte). Cryopreservation (CP) of cells preloaded into the device is highly desirable but may require prolonged exposure to cryoprotectants during loading and post-thaw manipulations. Here, we are reporting survival and function of a human islet cell line frozen as single cells or as islet-like cell clusters. The non-clusterized cells exhibited high cryosurvival after prolonged pre-freeze or post-thaw exposure to 10 percent DMSO. However, both clusterization and especially loading INPCs into the device reduced viable yield even without CP. The survived cryopreserved macro-encapsulated INPCs remained fully functional suggesting that CP of macro-encapsulated cells is a promising tool for cell based therapies.

Cellular responses to nicotinic receptor activation are decreased after prolonged exposure to galantamine in human neuroblastoma cells.

PubMed

Barik, Jacques; Dajas-Bailador, Federico; Wonnacott, Susan

2005-08-01

In this study, we have examined cellular responses of neuroblastoma SH-SY5Y cells after chronic treatment with galantamine, a drug used to treat Alzheimer's disease that has a dual mechanism of action: inhibition of acetylcholinesterase and allosteric potentiation of nicotinic acetylcholine receptors (nAChR). Acute experiments confirmed that maximum potentiation of nicotinic responses occurs at 1 microM galantamine; hence this concentration was chosen for chronic treatment. Exposure to 1 microM galantamine for 4 days decreased Ca(2+) responses (by 19.8+/-3.6%) or [(3)H]noradrenaline ([(3)H]NA) release (by 23.9+/-3.3%) elicited by acute application of nicotine. KCl-evoked increases in intracellular Ca(2+) were also inhibited by 10.0+/-1.9% after 4 days' treatment with galantamine. These diminished responses are consistent with the downregulation of downstream cellular processes. Ca(2+) responses evoked by activation of muscarinic acetylcholine receptors were unaffected by chronic galantamine treatment. Exposure to the more potent acetylcholinesterase inhibitor rivastigmine (1 microM) for 4 days failed to alter nicotine-, KCl-, or muscarinic receptor-evoked increases in intracellular Ca(2+). These observations support the hypothesis that chronic galantamine exerts its effects through interaction with nAChR in this cell line. Exposure to 10 microM nicotine for 4 days produced decreases in acute nicotine- (18.0+/-3.5%) and KCl-evoked Ca(2+) responses (10.6+/-2.5%) and nicotine-evoked [(3)H]NA release (26.0+/-3.3%) that are comparable to the effects of a corresponding exposure to galantamine. Treatment with 1 microM galantamine did not alter numbers of [(3)H]epibatidine-binding sites in SH-SY5Y cells, in contrast to 62% upregulation of these sites in response to 10 microM nicotine. Thus, chronic galantamine acts at nAChR to decrease subsequent functional responses to acute stimulation with nicotine or KCl. This effect appears to be independent of the upregulation of nAChR-binding sites.

Hard turning micro-machine tool

DOEpatents

DeVor, Richard E; Adair, Kurt; Kapoor, Shiv G

2013-10-22

A micro-scale apparatus for supporting a tool for hard turning comprises a base, a pivot coupled to the base, an actuator coupled to the base, and at least one member coupled to the actuator at one end and rotatably coupled to the pivot at another end. A tool mount is disposed on the at least one member. The at least one member defines a first lever arm between the pivot and the tool mount, and a second lever arm between the pivot and the actuator. The first lever arm has a length that is less than a length of the second lever arm. The actuator moves the tool mount along an arc.

Hydroponics as a valid tool to assess arsenic availability in mine soils.

PubMed

Moreno-Jiménez, E; Esteban, E; Fresno, T; de Egea, C López; Peñalosa, J M

2010-04-01

The low solubility of As in mine soils limits its phytoavailability. This makes the extrapolation of data obtained under hydroponic conditions unrealistic because the concentration in nutrient solution frequently overexposes plants to this metalloid. This work evaluates whether As supply in hydroponics resembles, to some extent, the As phytoavailable fraction in soils and the implications for phytoremediation. Phytotoxicity of As, in terms of biomass production, chlorophyll levels, and As concentrations in plants, was estimated and compared in both soils and hydroponics. In order for hydroponic conditions to be compared to soil conditions, plant exposure levels were measured in both cultures. Hydroponic As concentration ranging from 2-8microM equated to the same plant organ concentrations from soils with 700-3000mgkg(-1). Total and extractable As fractions exceeded those values, but As concentrations in pore water were bellow them. According to our results (i) hydroponics should include doses in the range 0-10microM As to allow the extrapolation of the results to As-polluted soils, and (ii) phytoextraction of As in mining sites will be limited by low As phytoavailability.

Cytotoxicity and mitogenicity assays with real-time and label-free monitoring of human granulosa cells with an impedance-based signal processing technology intergrating micro-electronics and cell biology.

PubMed

Oktem, Ozgur; Bildik, Gamze; Senbabaoglu, Filiz; Lack, Nathan A; Akin, Nazli; Yakar, Feridun; Urman, Defne; Guzel, Yilmaz; Balaban, Basak; Iwase, Akira; Urman, Bulent

2016-04-01

A recently developed technology (xCelligence) integrating micro-electronics and cell biology allows real-time, uninterrupted and quantitative analysis of cell proliferation, viability and cytotoxicity by measuring the electrical impedance of the cell population in the wells without using any labeling agent. In this study we investigated if this system is a suitable model to analyze the effects of mitogenic (FSH) and cytotoxic (chemotherapy) agents with different toxicity profiles on human granulosa cells in comparison to conventional methods of assessing cell viability, DNA damage, apoptosis and steroidogenesis. The system generated the real-time growth curves of the cells, and determined their doubling times, mean cell indices and generated dose-response curves after exposure to cytotoxic and mitogenic stimuli. It accurately predicted the gonadotoxicity of the drugs and distinguished less toxic agents (5-FU and paclitaxel) from more toxic ones (cisplatin and cyclophosphamide). This platform can be a useful tool for specific end-point assays in reproductive toxicology. Copyright © 2015 Elsevier Inc. All rights reserved.

Methamphetamine blood concentrations in human abusers: application to pharmacokinetic modeling.

PubMed

Melega, William P; Cho, Arthur K; Harvey, Dennis; Laćan, Goran

2007-04-01

Characterization of methamphetamine's (METH) dose-dependent effects on brain neurochemistry may represent a critical component for better understanding the range of resultant behavioral pathologies. Most human studies, however, have assessed only the effects of long term, high dose METH abuse (e.g., greater than 1000 mg/day) in individuals meeting DSM-IV criteria for METH dependence. Yet, for the majority of METH abusers, their patterns of METH exposure that consist of lower doses remain less well-characterized. In this study, blood samples were obtained from 105 individuals detained by police for possible criminal activity and testing positive for stimulants by EMIT assay. METH blood concentrations were subsequently quantified by GC-MS and were predominantly in the low micromolar range (0.1-11.1 microM), with median and mean values of 1.3 microM (0.19 mg/l) and 2 microM (0.3 mg/l), respectively. Pharmacokinetic calculations based on these measured values were used to estimate initial METH body burdens, the median value being 52 mg. Modeling a 52 mg dose for a 4 day-METH maintenance exposure pattern of 4 doses/day at 4 h intervals showed that blood concentrations remained between 1 and 4 microM during this period. Collectively, these data present evidence for a METH exposure pattern distinct from high dose-METH abuse and provide the rationale for assessing potential brain pathology associated with such lower dose-METH exposure.

Characterization of personal RF electromagnetic field exposure and actual absorption for the general public.

PubMed

Joseph, W; Vermeeren, G; Verloock, L; Heredia, Mauricio Masache; Martens, Luc

2008-09-01

In this paper, personal electromagnetic field exposure of the general public due to 12 different radiofrequency sources is characterized. Twenty-eight different realistic exposure scenarios based upon time, environment, activity, and location have been defined and a relevant number of measurements were performed with a personal exposure meter. Indoor exposure in office environments can be higher than outdoor exposure: 95th percentiles of field values due to WiFi ranged from 0.36 to 0.58 V m(-1), and for DECT values of 0.33 V m(-1) were measured. The downlink signals of GSM and DCS caused the highest outdoor exposures up to 0.52 V m(-1). The highest total field exposure occurred for mobile scenarios (inside a train or bus) from uplink signals of GSM and DCS (e.g., mobile phones) due to changing environmental conditions, handovers, and higher required transmitted signals from mobile phones due to penetration through windows while moving. A method to relate the exposure to the actual whole-body absorption in the human body is proposed. An application is shown where the actual absorption in a human body model due to a GSM downlink signal is determined. Fiftieth, 95th, and 99 th percentiles of the whole-body specific absorption rate (SAR) due to this GSM signal of 0.58 microW kg(-1), 2.08 microW kg(-1), and 5.01 microW kg(-1) are obtained for a 95th percentile of 0.26 V m(-1). A practical usable function is proposed for the relation between the whole-body SAR and the electric fields. The methodology of this paper enables epidemiological studies to make an analysis in combination with both electric field and actual whole-body SAR values and to compare exposure with basic restrictions.

Inflammatory gene networks in term human decidual cells define a potential signature for cytokine-mediated parturition.

PubMed

Ibrahim, Sherrine A; Ackerman, William E; Summerfield, Taryn L; Lockwood, Charles J; Schatz, Frederick; Kniss, Douglas A

2016-02-01

Inflammation is a proximate mediator of preterm birth and fetal injury. During inflammation several microRNAs (22 nucleotide noncoding ribonucleic acid (RNA) molecules) are up-regulated in response to cytokines such as interleukin-1β. MicroRNAs, in most cases, fine-tune gene expression, including both up-regulation and down-regulation of their target genes. However, the role of pro- and antiinflammatory microRNAs in this process is poorly understood. The principal goal of the work was to examine the inflammatory genomic profile of human decidual cells challenged with a proinflammatory cytokine known to be present in the setting of preterm parturition. We determined the coding (messenger RNA) and noncoding (microRNA) sequences to construct a network of interacting genes during inflammation using an in vitro model of decidual stromal cells. The effects of interleukin-1β exposure on mature microRNA expression were tested in human decidual cell cultures using the multiplexed NanoString platform, whereas the global inflammatory transcriptional response was measured using oligonucleotide microarrays. Differential expression of select transcripts was confirmed by quantitative real time-polymerase chain reaction. Bioinformatics tools were used to infer transcription factor activation and regulatory interactions. Interleukin-1β elicited up- and down-regulation of 350 and 78 nonredundant transcripts (false discovery rate < 0.1), respectively, including induction of numerous cytokines, chemokines, and other inflammatory mediators. Whereas this transcriptional response included marked changes in several microRNA gene loci, the pool of fully processed, mature microRNA was comparatively stable following a cytokine challenge. Of a total of 6 mature microRNAs identified as being differentially expressed by NanoString profiling, 2 (miR-146a and miR-155) were validated by quantitative real time-polymerase chain reaction. Using complementary bioinformatics approaches, activation of several inflammatory transcription factors could be inferred downstream of interleukin-1β based on the overall transcriptional response. Further analysis revealed that miR-146a and miR-155 both target genes involved in inflammatory signaling, including Toll-like receptor and mitogen-activated protein kinase pathways. Stimulation of decidual cells with interleukin-1β alters the expression of microRNAs that function to temper proinflammatory signaling. In this setting, some microRNAs may be involved in tissue-level inflammation during the bulk of gestation and assist in pregnancy maintenance. Copyright © 2016 Elsevier Inc. All rights reserved.

Validation of Lower Tier Exposure Tools Used for REACH: Comparison of Tools Estimates With Available Exposure Measurements.

PubMed

van Tongeren, Martie; Lamb, Judith; Cherrie, John W; MacCalman, Laura; Basinas, Ioannis; Hesse, Susanne

2017-10-01

Tier 1 exposure tools recommended for use under REACH are designed to easily identify situations that may pose a risk to health through conservative exposure predictions. However, no comprehensive evaluation of the performance of the lower tier tools has previously been carried out. The ETEAM project aimed to evaluate several lower tier exposure tools (ECETOC TRA, MEASE, and EMKG-EXPO-TOOL) as well as one higher tier tool (STOFFENMANAGER®). This paper describes the results of the external validation of tool estimates using measurement data. Measurement data were collected from a range of providers, both in Europe and United States, together with contextual information. Individual measurement and aggregated measurement data were obtained. The contextual information was coded into the tools to obtain exposure estimates. Results were expressed as percentage of measurements exceeding the tool estimates and presented by exposure category (non-volatile liquid, volatile liquid, metal abrasion, metal processing, and powder handling). We also explored tool performance for different process activities as well as different scenario conditions and exposure levels. In total, results from nearly 4000 measurements were obtained, with the majority for the use of volatile liquids and powder handling. The comparisons of measurement results with tool estimates suggest that the tools are generally conservative. However, the tools were more conservative when estimating exposure from powder handling compared to volatile liquids and other exposure categories. In addition, results suggested that tool performance varies between process activities and scenario conditions. For example, tools were less conservative when estimating exposure during activities involving tabletting, compression, extrusion, pelletisation, granulation (common process activity PROC14) and transfer of substance or mixture (charging and discharging) at non-dedicated facilities (PROC8a; powder handling only). With the exception of STOFFENMANAGER® (for estimating exposure during powder handling), the tools were less conservative for scenarios with lower estimated exposure levels. This is the most comprehensive evaluation of the performance of REACH exposure tools carried out to date. The results show that, although generally conservative, the tools may not always achieve the performance specified in the REACH guidance, i.e. using the 75th or 90th percentile of the exposure distribution for the risk characterisation. Ongoing development, adjustment, and recalibration of the tools with new measurement data are essential to ensure adequate characterisation and control of worker exposure to hazardous substances. © The Author 2017. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Monitoring micro-crack healing in an engineered cementitious composite using the environmental scanning electron microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suryanto, B., E-mail: b.suryanto@hw.ac.uk; Buckman

Environmental Scanning Electron Microscopy (ESEM) is used to study the origin of micro-crack healing in an Engineered Cementitious Composite (ECC). ESEM images were acquired from ECC specimens cut from pre-cracked, dog-bone samples which then subjected to submerged curing followed by exposure to the natural environment. The mineralogical and chemical compositions of the healing products were determined using the EDX facility in the ESEM. It is shown that the precipitation of calcium carbonate is the main contributor to micro-crack healing at the crack mouth. The healing products initially appeared in an angular rhombohedral morphology which then underwent a discernable transformation inmore » size, shape and surface texture, from relatively flat and smooth to irregular and rough, resembling the texture of the original surface areas surrounding the micro-cracks. It is also shown that exposure to the natural environment, involving intermittent wetting/drying cycles, promotes additional crystal growth, which indicates enhanced self-healing capability in this environment. - Highlights: •ESEM with EDX used to characterize the origin of micro-crack healing in an ECC •Evolution of healing precipitates studied at three specific locations over four weeks •Specimens exposed to laboratory environment, followed by the natural environment •Calcium carbonate is the main contributor to crack healing at the crack mouth. •Outdoor exposure involving intermittent rain promotes additional crystal growth.« less

The CULTEX RFS: A Comprehensive Technical Approach for the In Vitro Exposure of Airway Epithelial Cells to the Particulate Matter at the Air-Liquid Interface

PubMed Central

Aufderheide, Michaela; Hochrainer, Dieter

2013-01-01

The EU Regulation on Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) demands the implementation of alternative methods for analyzing the hazardous effects of chemicals including particulate formulations. In the field of inhalation toxicology, a variety of in vitro models have been developed for such studies. To simulate the in vivo situation, an adequate exposure device is necessary for the direct exposure of cultivated lung cells at the air-liquid interface (ALI). The CULTEX RFS fulfills these requirements and has been optimized for the exposure of cells to atomized suspensions, gases, and volatile compounds as well as micro- and nanosized particles. This study provides information on the construction and functional aspects of the exposure device. By using the Computational Fluid Dynamics (CFD) analysis, the technical design was optimized to realize a stable, reproducible, and homogeneous deposition of particles. The efficiency of the exposure procedure is demonstrated by exposing A549 cells dose dependently to lactose monohydrate, copper(II) sulfate, copper(II) oxide, and micro- and nanoparticles. All copper compounds induced cytotoxic effects, most pronounced for soluble copper(II) sulfate. Micro- and nanosized copper(II) oxide also showed a dose-dependent decrease in the cell viability, whereby the nanosized particles decreased the metabolic activity of the cells more severely. PMID:23509768

Tool Condition Monitoring in Micro-End Milling using wavelets

NASA Astrophysics Data System (ADS)

Dubey, N. K.; Roushan, A.; Rao, U. S.; Sandeep, K.; Patra, K.

2018-04-01

In this work, Tool Condition Monitoring (TCM) strategy is developed for micro-end milling of titanium alloy and mild steel work-pieces. Full immersion slot milling experiments are conducted using a solid tungsten carbide end mill for more than 1900 s to have reasonable amount of tool wear. During the micro-end milling process, cutting force and vibration signals are acquired using Kistler piezo-electric 3-component force dynamometer (9256C2) and accelerometer (NI cDAQ-9188) respectively. The force components and the vibration signals are processed using Discrete Wavelet Transformation (DWT) in both time and frequency window. 5-level wavelet packet decomposition using Db-8 wavelet is carried out and the detailed coefficients D1 to D5 for each of the signals are obtained. The results of the wavelet transformation are correlated with the tool wear. In case of vibration signals, de-noising is done for higher frequency components (D1) and force signals were de-noised for lower frequency components (D5). Increasing value of MAD (Mean Absolute Deviation) of the detail coefficients for successive channels depicted tool wear. The predictions of the tool wear are confirmed from the actual wear observed in the SEM of the worn tool.

Physicochemical Characteristics of Dust Particles in HVOF Spraying and Occupational Hazards: Case Study in a Chinese Company

NASA Astrophysics Data System (ADS)

Huang, Haihong; Li, Haijun; Li, Xinyu

2016-06-01

Dust particles generated in thermal spray process can cause serious health problems to the workers. Dust particles generated in high velocity oxy-fuel (HVOF) spraying WC-Co coatings were characterized in terms of mass concentrations, particle size distribution, micro morphologies, and composition. Results show that the highest instantaneous exposure concentration of dust particles in the investigated thermal spray workshop is 140 mg/m3 and the time-weighted average concentration is 34.2 mg/m3, which are approximately 8 and 4 times higher than the occupational exposure limits in China, respectively. The large dust particles above 10 μm in size present a unique morphology of polygonal or irregular block of crushed powder, and smaller dust particles mainly exist in the form of irregular or flocculent agglomerates. Some heavy metals, such as chromium, cobalt, and nickel, are also found in the air of the workshop and their concentrations are higher than the limits. Potential occupational hazards of the dust particles in the thermal spray process are further analyzed based on their characteristics and the workers' exposure to the nanoparticles is assessed using a control banding tool.

Routine versus Catastrophic Influences on the Developing Child

PubMed Central

Odgers, Candice L.; Jaffee, Sara R.

2014-01-01

Exposure to toxic stress accelerates the wear and tear on children’s developing bodies and leaves a lasting mark on adult health. Prior research has focused mainly on children exposed to extreme forms of adversity, such as maltreatment and extreme neglect. However, repeated exposure to less severe, but often chronic stressors is likely to play as large, if not larger, of a role in forecasting children’s future mental and physical health. New tools from neuroscience, biology, epigenetics, and the social sciences are helping to isolate when and how the foundations for adult health are shaped by childhood experiences. We are now in the position to understand how adversity, in both extreme and more mundane forms, contributes to the adult health burden and to identify features in children’s families and environments that can be strengthened to buffer the effects of toxic stressors. We are now positioned to develop and implement innovative approaches to child policy and practice that are rooted in an understanding of how exposure to toxic stressors can become biologically embedded. The stage is set for the creation of new interventions—on both grand and micro scales—to reduce previously intractable health disparities. PMID:23297656

Nocturnal 6-hydroxymelatonin sulfate excretion in female workers exposed to magnetic fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Juutilainen, J; Stevens, Richard G.; Anderson, Larry E.

The objective of this study was to determine whether daytime occupational exposure to extremely low frequency magnetic fields (MFs) suppresses nocturnal melatonin production. Sixty female volunteers were recruited. Thirty-nine worked in a garment factory, and 21 office workers served as a reference group. Exposure assessment was based on the type of sewing machine used and MF measurements around each type of machine. Eye-level MF flux density was used to classify the operators to higher (> 1 microT) and lower (0.3-1 microT) exposure categories. A third group of factory workers had diverse MF exposures from other sources. The reference group hadmore » average exposure of about 0.15 microT. Urine samples were collected on Friday and Monday for three consecutive weeks. Melatonin production was assessed as urinary 6-hydroxymelatonin sulfate (6-OHMS) excretion. The ratio of Friday morning/Monday morning 6-OHMS was used to test the hypothesis that melatonin production is suppressed after 4 days of occupational MF exposure with significant recovery during the weekend. Possible chronic suppression of melatonin production was evaluated by studying exposure-related differences in the Friday values by multivariate regression analysis. The Monday/Friday ratios were close to 1.0, suggesting that there is no increase in melatonin production over the weekend. The average 6-OHMS excretion on Friday was lower among the factory workers than in the reference group, but no monotonous dose-response was observed. Multivariate regression analysis identified MF exposure, smoking, and age as significant explanatory variables associated with decreased 6-OHMS excretion.« less

Insensitivity of cardiovascular function to low power cm-/mm-microwaves.

PubMed

Kantz, J; Müller, J; Hadeler, K P; Landstorfer, F M; Lang, F

2005-06-01

A previous study failed to disclose an effect of short (15 min) exposure to low level energy microwaves (3 microW/cm2) emitted by a commercially available automobile radar system (77 GHz) for adaptive cruise control (ACC) on cardiovascular function. The present study explored whether a 15 min exposure to higher level energy microwaves of frequencies varying from 5.8 to 110 GHz influences cardiovascular function. To this end heart rate, skin temperature (thermocouple), skin conductance (Ag/AgCl electrodes), systolic and diastolic blood pressure (automatic cuff) were recorded in 50 test persons before, during and after a 15 min exposure to a sequential pattern of microwaves varying from 5.8 to 110 GHz (59.7 microW/cm2). After an equilibration period of 30 min the first group of test persons and after additional 30 min the second group of test persons were exposed. The study has been performed in a strict double blind design. While significant effects on the measured parameters were observed depending on time ("calming" effect), no significant difference was observed between exposure and sham exposure to microwaves. In view of the small scatter of the data the present study rules out physiologically relevant effects of moderate energy (59.7 microW/cm2) microwaves varying from 5.8 to 110 GHz on cardiovascular function.

Exposure to Endocrine Disruptor Induces Transgenerational Epigenetic Deregulation of MicroRNAs in Primordial Germ Cells

PubMed Central

Brieño-Enríquez, Miguel A.; García-López, Jesús; Cárdenas, David B.; Guibert, Sylvain; Cleroux, Elouan; Děd, Lukas; Hourcade, Juan de Dios; Pěknicová, Jana; Weber, Michael; del Mazo, Jesús

2015-01-01

In mammals, germ cell differentiation is initiated in the Primordial Germ Cells (PGCs) during fetal development. Prenatal exposure to environmental toxicants such as endocrine disruptors may alter PGC differentiation, development of the male germline and induce transgenerational epigenetic disorders. The anti-androgenic compound vinclozolin represents a paradigmatic example of molecule causing transgenerational effects on germ cells. We performed prenatal exposure to vinclozolin in mice and analyzed the phenotypic and molecular changes in three successive generations. A reduction in the number of embryonic PGCs and increased rate of apoptotic cells along with decrease of fertility rate in adult males were observed in F1 to F3 generations. Blimp1 is a crucial regulator of PGC differentiation. We show that prenatal exposure to vinclozolin deregulates specific microRNAs in PGCs, such as miR-23b and miR-21, inducing disequilibrium in the Lin28/let-7/Blimp1 pathway in three successive generations of males. As determined by global maps of cytosine methylation, we found no evidence for prominent changes in DNA methylation in PGCs or mature sperm. Our data suggest that embryonic exposure to environmental endocrine disruptors induces transgenerational epigenetic deregulation of expression of microRNAs affecting key regulatory pathways of germ cells differentiation. PMID:25897752

Microenvironment Tracker (MicroTrac) | Science Inventory ...

EPA Pesticide Factsheets

Epidemiologic studies have shown associations between air pollution concentrations measured at central-site ambient monitors and adverse health outcomes. Using central-site concentrations as exposure surrogates, however, can lead to exposure errors due to time spent in various indoor and outdoor microenvironments (ME) with pollutant concentrations that can be substantially different from central-site concentrations. These exposure errors can introduce bias and incorrect confidence intervals in health effect estimates, which diminish the power of such studies to establish correct conclusions about the exposure and health effects association. The significance of this issue was highlighted in the National Research Council (NRC) Report “Research Priorities for Airborne Particulate Matter”, which recommends that EPA address exposure error in health studies. To address this limitation, we developed MicroTrac, an automated classification model that estimates time of day and duration spent in eight ME (indoors and outdoors at home, work, school; inside vehicles; other locations) from personal global positioning system (GPS) data and geocoded boundaries of buildings (e.g., home, work, school). MicroTrac has several innovative design features: (1) using GPS signal quality to account for GPS signal loss inside certain buildings, (2) spatial buffering of building boundaries to account for the spatial inaccuracy of the GPS device, and (3) temporal buffering of GPS positi

Applications of X-Ray Micro-Beam for Data Collection.

PubMed

Sanishvili, Ruslan; Fischetti, Robert F

2017-01-01

Micro-diffraction tools for macromolecular crystallography, first developed at the end of 1990s and now an integral part of many synchrotron beamlines, enable some of the experiments which were not feasible just a decade or so ago. These include data collection from very small samples, just a few micrometers in size; from larger, but severely inhomogeneous samples; and from samples which are optically invisible. Improved micro-diffraction tools led to improved signal-to-noise ratio, to mitigation of radiation damage in some cases, and to better-designed diffraction experiments. Small, micron-scale beams can be attained in different ways and knowing the details of the implementation is important in order to design the diffraction experiment properly. Similarly, precision, reproducibility and stability of the goniometry, and caveats of detection systems need to be taken into account. Lastly, to make micro-diffraction widely applicable, the sophistication, robustness, and user-friendliness of these tools are just as important as the technical capabilities.

78 FR 37176 - Addition of Nonylphenol Category; Community Right-to-Know Toxic Chemical Release Reporting

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-20

...]g/L. Nearly all larvae were abnormal at the two highest exposure concentrations (>= 53 [micro]g/L... was delayed at the two highest concentrations (14 and 23 [micro]g/L). Fathead minnow survival was... [micro]g/L (Ref. 35). 2. In Vivo Responses in Fish. The protein vitellogenin, which is produced in the...

A facile and low-cost micro fabrication material: flash foam.

PubMed

He, Yong; Xiao, Xiao; Wu, Yan; Fu, Jian-zhong

2015-08-28

Although many microfabrication methods have been reported, the preliminary replication templates used in most microfabrication still depend on the expensive and long-period photolithography. This paper explores an alternative replication templates based on a daily used material, flash foam (FF), and proposes a facile microfabrication method, flash foam stamp lithography (FFSL). When FF is exposed with a desired pattern mask, the negative of the pattern is transferred to its surface and micro structures are formed due to the shrinkage of the exposed area. As FF is commonly used in personal stamps, FFSL is very simple and cost-effective. In this paper, we demonstrated that FF is a good and low-cost template for many micro fabrication methods, such as micro casting and soft lithography. Thus, designing and fabricating micro structures at personal office immediately become possible with FFSL. Furthermore, we demonstrated that multi-scale micro structures can be easily fabricated by double exposure with FFSL. Skin textures is used as another case to demonstrate that FFSL can fabricate structures with different depth in a single exposure. As a result, FF shows a promising future in biology, and analytical chemistry, such as rapid fabrication of point of care diagnostics and microfluidic analytical devices with low cost.

Finite Element Simulations of Micro Turning of Ti-6Al-4V using PCD and Coated Carbide tools

NASA Astrophysics Data System (ADS)

Jagadesh, Thangavel; Samuel, G. L.

2017-02-01

The demand for manufacturing axi-symmetric Ti-6Al-4V implants is increasing in biomedical applications and it involves micro turning process. To understand the micro turning process, in this work, a 3D finite element model has been developed for predicting the tool chip interface temperature, cutting, thrust and axial forces. Strain gradient effect has been included in the Johnson-Cook material model to represent the flow stress of the work material. To verify the simulation results, experiments have been conducted at four different feed rates and at three different cutting speeds. Since titanium alloy has low Young's modulus, spring back effect is predominant for higher edge radius coated carbide tool which leads to the increase in the forces. Whereas, polycrystalline diamond (PCD) tool has smaller edge radius that leads to lesser forces and decrease in tool chip interface temperature due to high thermal conductivity. Tool chip interface temperature increases by increasing the cutting speed, however the increase is less for PCD tool as compared to the coated carbide tool. When uncut chip thickness decreases, there is an increase in specific cutting energy due to material strengthening effects. Surface roughness is higher for coated carbide tool due to ploughing effect when compared with PCD tool. The average prediction error of finite element model for cutting and thrust forces are 11.45 and 14.87 % respectively.

Preliminary design of mesoscale turbocompressor and rotordynamics tests of rotor bearing system

NASA Astrophysics Data System (ADS)

Hossain, Md Saddam

2011-12-01

A mesoscale turbocompressor spinning above 500,000 RPM is evolutionary technology for micro turbochargers, turbo blowers, turbo compressors, micro-gas turbines, auxiliary power units, etc for automotive, aerospace, and fuel cell industries. Objectives of this work are: (1) to evaluate different air foil bearings designed for the intended applications, and (2) to design & perform CFD analysis of a micro-compressor. CFD analysis of shrouded 3-D micro compressor was conducted using Ansys Bladegen as blade generation tool, ICEM CFD as mesh generation tool, and CFX as main solver for different design and off design cases and also for different number of blades. Comprehensive experimental facilities for testing the turbocompressor system have been also designed and proposed for future work.

The Use of Micro-Blogging for Teacher Professional Development Support and Personalized Professional Development

ERIC Educational Resources Information Center

Smith, Saress Ellerbe

2016-01-01

The purpose of this qualitative study was to look at how teachers use micro-blogging, in this case Twitter (www.twitter.com), for their own personalized professional learning and how effective Twitter is as a professional development (PD) tool. In order to measure the effectiveness of the tool, the researcher first gleaned nine essential…

Hybrid micromachining using a nanosecond pulsed laser and micro EDM

NASA Astrophysics Data System (ADS)

Kim, Sanha; Kim, Bo Hyun; Chung, Do Kwan; Shin, Hong Shik; Chu, Chong Nam

2010-01-01

Micro electrical discharge machining (micro EDM) is a well-known precise machining process that achieves micro structures of excellent quality for any conductive material. However, the slow machining speed and high tool wear are main drawbacks of this process. Though the use of deionized water instead of kerosene as a dielectric fluid can reduce the tool wear and increase the machine speed, the material removal rate (MRR) is still low. In contrast, laser ablation using a nanosecond pulsed laser is a fast and non-wear machining process but achieves micro figures of rather low quality. Therefore, the integration of these two processes can overcome the respective disadvantages. This paper reports a hybrid process of a nanosecond pulsed laser and micro EDM for micromachining. A novel hybrid micromachining system that combines the two discrete machining processes is introduced. Then, the feasibility and characteristics of the hybrid machining process are investigated compared to conventional EDM and laser ablation. It is verified experimentally that the machining time can be effectively reduced in both EDM drilling and milling by rapid laser pre-machining prior to micro EDM. Finally, some examples of complicated 3D micro structures fabricated by the hybrid process are shown.

Effects of exposure to GSM mobile phone base station signals on salivary cortisol, alpha-amylase, and immunoglobulin A.

PubMed

Augner, Christoph; Hacker, Gerhard W; Oberfeld, Gerd; Florian, Matthias; Hitzl, Wolfgang; Hutter, Jörg; Pauser, Gernot

2010-06-01

The present study aimed to test whether exposure to radiofrequency electromagnetic fields (RF-EMF) emitted by mobile phone base stations may have effects on salivary alpha-amylase, immunoglobulin A (IgA), and cortisol levels. Fifty seven participants were randomly allocated to one of three different experimental scenarios (22 participants to scenario 1, 26 to scenario 2, and 9 to scenario 3). Each participant went through five 50-minute exposure sessions. The main RF-EMF source was a GSM-900-MHz antenna located at the outer wall of the building. In scenarios 1 and 2, the first, third, and fifth sessions were "low" (median power flux density 5.2 microW/m(2)) exposure. The second session was "high" (2126.8 microW/m(2)), and the fourth session was "medium" (153.6 microW/m(2)) in scenario 1, and vice versa in scenario 2. Scenario 3 had four "low" exposure conditions, followed by a "high" exposure condition. Biomedical parameters were collected by saliva samples three times a session. Exposure levels were created by shielding curtains. In scenario 3 from session 4 to session 5 (from "low" to "high" exposure), an increase of cortisol was detected, while in scenarios 1 and 2, a higher concentration of alpha-amylase related to the baseline was identified as compared to that in scenario 3. IgA concentration was not significantly related to the exposure. RF-EMF in considerably lower field densities than ICNIRP-guidelines may influence certain psychobiological stress markers. Copyright © 2010 The Editorial Board of Biomedical and Environmental Sciences. Published by Elsevier B.V. All rights reserved.

Release of MicroRNAs into Body Fluids from Ten Organs of Mice Exposed to Cigarette Smoke

PubMed Central

Izzotti, Alberto; Longobardi, Mariagrazia; La Maestra, Sebastiano; Micale, Rosanna T.; Pulliero, Alessandra; Camoirano, Anna; Geretto, Marta; D'Agostini, Francesco; Balansky, Roumen; Miller, Mark Steven; Steele, Vernon E.; De Flora, Silvio

2018-01-01

Purpose: MicroRNAs are small non-coding RNAs that regulate gene expression, thereby playing a role in a variety of physiological and pathophysiological states. Exposure to cigarette smoke extensively downregulates microRNA expression in pulmonary cells of mice, rats, and humans. Cellular microRNAs are released into body fluids, but a poor parallelism was previously observed between lung microRNAs and circulating microRNAs. The purpose of the present study was to validate the application of this epigenetic biomarker by using less invasive collection procedures. Experimental design: Using microarray analyses, we measured 1135 microRNAs in 10 organs and 3 body fluids of mice that were either unexposed or exposed to mainstream cigarette smoke for up to 8 weeks. The results obtained with selected miRNAs were validated by qPCR. Results: The lung was the main target affected by smoke (190 dysregulated miRNAs), followed by skeletal muscle (180), liver (138), blood serum (109), kidney (96), spleen (89), stomach (36), heart (33), bronchoalveolar lavage fluid (32), urine (27), urinary bladder (12), colon (5), and brain (0). Skeletal muscle, kidney, and lung were the most important sources of smoke-altered microRNAs in blood serum, urine, and bronchoalveolar lavage fluid, respectively. Conclusions: microRNA expression analysis was able to identify target organs after just 8 weeks of exposure to smoke, well before the occurrence of any detectable histopathological alteration. The present translational study validates the use of body fluid microRNAs as biomarkers applicable to human biomonitoring for mechanistic studies, diagnostic purposes, preventive medicine, and therapeutic strategies. PMID:29721069

Structure of catalase determined by MicroED

PubMed Central

Nannenga, Brent L; Shi, Dan; Hattne, Johan; Reyes, Francis E; Gonen, Tamir

2014-01-01

MicroED is a recently developed method that uses electron diffraction for structure determination from very small three-dimensional crystals of biological material. Previously we used a series of still diffraction patterns to determine the structure of lysozyme at 2.9 Å resolution with MicroED (Shi et al., 2013). Here we present the structure of bovine liver catalase determined from a single crystal at 3.2 Å resolution by MicroED. The data were collected by continuous rotation of the sample under constant exposure and were processed and refined using standard programs for X-ray crystallography. The ability of MicroED to determine the structure of bovine liver catalase, a protein that has long resisted atomic analysis by traditional electron crystallography, demonstrates the potential of this method for structure determination. DOI: http://dx.doi.org/10.7554/eLife.03600.001 PMID:25303172

A Comprehensive Study of a Micro-Channel Heat Sink Using Integrated Thin-Film Temperature Sensors

PubMed Central

Wang, Tao; Wang, Jiejun; He, Jian; Wu, Chuangui; Luo, Wenbo; Shuai, Yao; Zhang, Wanli; Chen, Xiancai; Zhang, Jian; Lin, Jia

2018-01-01

A micro-channel heat sink is a promising cooling method for high power integrated circuits (IC). However, the understanding of such a micro-channel device is not sufficient, because the tools for studying it are very limited. The details inside the micro-channels are not readily available. In this letter, a micro-channel heat sink is comprehensively studied using the integrated temperature sensors. The highly sensitive thin film temperature sensors can accurately monitor the temperature change in the micro-channel in real time. The outstanding heat dissipation performance of the micro-channel heat sink is proven in terms of maximum temperature, cooling speed and heat resistance. The temperature profile along the micro-channel is extracted, and even small temperature perturbations can be detected. The heat source formed temperature peak shifts towards the flow direction with the increasing flow rate. However, the temperature non-uniformity is independent of flow rate, but solely dependent on the heating power. Specific designs for minimizing the temperature non-uniformity are necessary. In addition, the experimental results from the integrated temperature sensors match the simulation results well. This can be used to directly verify the modeling results, helping to build a convincing simulation model. The integrated sensor could be a powerful tool for studying the micro-channel based heat sink. PMID:29351248

A Comprehensive Study of a Micro-Channel Heat Sink Using Integrated Thin-Film Temperature Sensors.

PubMed

Wang, Tao; Wang, Jiejun; He, Jian; Wu, Chuangui; Luo, Wenbo; Shuai, Yao; Zhang, Wanli; Chen, Xiancai; Zhang, Jian; Lin, Jia

2018-01-19

A micro-channel heat sink is a promising cooling method for high power integrated circuits (IC). However, the understanding of such a micro-channel device is not sufficient, because the tools for studying it are very limited. The details inside the micro-channels are not readily available. In this letter, a micro-channel heat sink is comprehensively studied using the integrated temperature sensors. The highly sensitive thin film temperature sensors can accurately monitor the temperature change in the micro-channel in real time. The outstanding heat dissipation performance of the micro-channel heat sink is proven in terms of maximum temperature, cooling speed and heat resistance. The temperature profile along the micro-channel is extracted, and even small temperature perturbations can be detected. The heat source formed temperature peak shifts towards the flow direction with the increasing flow rate. However, the temperature non-uniformity is independent of flow rate, but solely dependent on the heating power. Specific designs for minimizing the temperature non-uniformity are necessary. In addition, the experimental results from the integrated temperature sensors match the simulation results well. This can be used to directly verify the modeling results, helping to build a convincing simulation model. The integrated sensor could be a powerful tool for studying the micro-channel based heat sink.

High-throughput PBPK and Microdosimetry: Cell-level Exposures in a Virtual Tissue Context (WC9)

EPA Science Inventory

Toxicokinetic (TK) models can determine whether chemical exposures produce potentially hazardous tissue concentrations. Tissue microdosimetry TK models relate whole-body chemical exposures to cell-scale concentrations. As a proof of concept, we approximated the micro-anatomic arc...

Design of Friction Stir Spot Welding Tools by Using a Novel Thermal-Mechanical Approach

PubMed Central

Su, Zheng-Ming; Qiu, Qi-Hong; Lin, Pai-Chen

2016-01-01

A simple thermal-mechanical model for friction stir spot welding (FSSW) was developed to obtain similar weld performance for different weld tools. Use of the thermal-mechanical model and a combined approach enabled the design of weld tools for various sizes but similar qualities. Three weld tools for weld radii of 4, 5, and 6 mm were made to join 6061-T6 aluminum sheets. Performance evaluations of the three weld tools compared fracture behavior, microstructure, micro-hardness distribution, and welding temperature of welds in lap-shear specimens. For welds made by the three weld tools under identical processing conditions, failure loads were approximately proportional to tool size. Failure modes, microstructures, and micro-hardness distributions were similar. Welding temperatures correlated with frictional heat generation rate densities. Because the three weld tools sufficiently met all design objectives, the proposed approach is considered a simple and feasible guideline for preliminary tool design. PMID:28773800

Design of Friction Stir Spot Welding Tools by Using a Novel Thermal-Mechanical Approach.

PubMed

Su, Zheng-Ming; Qiu, Qi-Hong; Lin, Pai-Chen

2016-08-09

A simple thermal-mechanical model for friction stir spot welding (FSSW) was developed to obtain similar weld performance for different weld tools. Use of the thermal-mechanical model and a combined approach enabled the design of weld tools for various sizes but similar qualities. Three weld tools for weld radii of 4, 5, and 6 mm were made to join 6061-T6 aluminum sheets. Performance evaluations of the three weld tools compared fracture behavior, microstructure, micro-hardness distribution, and welding temperature of welds in lap-shear specimens. For welds made by the three weld tools under identical processing conditions, failure loads were approximately proportional to tool size. Failure modes, microstructures, and micro-hardness distributions were similar. Welding temperatures correlated with frictional heat generation rate densities. Because the three weld tools sufficiently met all design objectives, the proposed approach is considered a simple and feasible guideline for preliminary tool design.

Capillary-tube-based oxygen/argon micro-plasma system for the inactivation of bacteria suspended in aqueous solution.

PubMed

Weng, Chih-Chiang; Liao, Juinn-Der; Chen, Hsin-Hung; Lin, Tung-Yi; Huang, Chih-Ling

2011-09-01

An aqueous solution containing Escherichia coli can be completely inactivated within a short treatment time using a capillary-tube-based oxygen/argon micro-plasma source. A capillary-tube-based oxygen/argon micro-plasma system with a hollow inner electrode was ignited by a 13.56 MHz radio frequency power supply with a matching network and characterised by optical emission spectroscopy. An aqueous solution containing E. coli was then treated at various the working distances, plasma exposure durations, and oxygen ratios in argon micro-plasma. The treated bacteria were then assessed and qualitatively investigated. The morphologies of treated bacteria were examined using a scanning electron microscope (SEM). In the proposed oxygen/argon micro-plasma system, the intensities of the main emission lines of the excited species, nitric oxide (NO), hydrated oxide (OH), argon (Ar), and atomic oxygen (O), fluctuated with the addition of oxygen to argon micro-plasma. Under a steady state of micro-plasma generation, the complete inactivation of E. coli in aqueous solution was achieved within 90 s of argon micro-plasma exposure time with a working distance of 3 mm. SEM micrographs reveal obvious morphological damage to the treated E. coli. The addition of oxygen to argon micro-plasma increased the variety of O-containing excited species. At a given supply power, the relative intensities of the excited species, NO and OH, correlated with the ultraviolet (UV) intensity, decreased. For the proposed capillary-tube-based micro-plasma system with a hollow inner electrode, the oxygen/argon micro-plasma source is efficient in inactivating E. coli in aqueous solution. The treatment time required for the inactivation process decreases with decreasing working distance or the increasing synthesised effect of reactive species and UV intensity.

Serum and urine inorganic fluoride concentrations and urine oxalate concentrations following methoxyflurane anesthesia in the dog.

PubMed

Brunson, D B; Stowe, C M; McGrath, C J

1979-02-01

Plasma fluoride, urine fluoride and urine oxalate concentrations were measured before administering an anesthetic to 8 dogs, and at 0, 3, 9, 24, 48, and 72 hours following 1.5 hours of anesthesia with 1% methoxyflurane. Plasma and urine osmolalities were measured and compared with fluoride and oxalate values. Fluoride concentration increased in both plasma and urine following anesthesia when compared with the preanesthetic concentrations. Maximum mean plasma inorganic fluoride was 106.71 mumoles per liter (+/- 25.44 SE) at 9 hours after exposure to methoxyflurane was completed. By 72 hours after exposure to methoxyflurane the plasma fluoride concentration was 23.47 microM/L (+/- 5.74 SE). Mean urine inorganic fluoride concentration was highest at 9 hours after exposure to methoxyflurane and reached 6047.03 microM/L (+/- 1378.46 SE) as compared to the mean preanesthetic base-line concentration of 542.68 microM/L (+/- 132.93 SE), and the 72 hour mean urine fluoride concentration which was 1593.78 microM/L (+/- 579.46 SE). Urine oxalate concentrations, when compared with urine osmolality (mg/mOsm), increased throughout the study. The 72-hour concentration after exposure to methoxyflurane was 2.5 times the preanesthetic (mg/mOsm) oxalate concentration. Plasma osmolality did not change markedly during the study. Urine osmolalities varied between animals and collection times, but a consistent pattern did not occur. Clinical and laboratory signs of renal dysfunction were not observed in any animal during the study.

Effect of a nighttime magnetic field exposure on sleep patterns in young women.

PubMed

Tworoger, Shelley S; Davis, Scott; Emerson, Scott S; Mirick, Dana K; Lentz, Martha J; McTiernan, Anne

2004-08-01

Since poor sleep quality is associated with multiple health problems, it is important to understand factors that may affect sleep patterns. The purpose of this study was to determine the effect of a continuous, 60-Hz, nighttime magnetic field exposure on sleep outcomes in young women sleeping at home. The study was a randomized crossover trial, comparing intervention (0.5-1.0 micro T above ambient levels) with ambient magnetic field levels, during two 5-night measurement periods. Subjects lived in the Seattle, Washington, area and were 20-40 years of age, had regular menstrual cycles, were not taking oral contraceptives, and had not breastfed or been pregnant during the previous year. The study was conducted between March and September of 2001. Sleep outcomes were measured via actigraphy. The range of magnetic field exposure was 0.001-0.50 micro T during the ambient period and 0.41-1.21 micro T during the intervention period. Sleep outcomes were not significantly different between the intervention and the ambient measurement periods. The intervention magnetic field had no effect on sleep patterns, suggesting that this exposure may not be an important factor in predicting sleep of young women who sleep at home.

EUV microexposures at the ALS using the 0.3-NA MET projectionoptics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Naulleau, Patrick; Goldberg, Kenneth A.; Anderson, Erik

2005-09-01

The recent development of high numerical aperture (NA) EUV optics such as the 0.3-NA Micro Exposure Tool (MET) optic has given rise to a new class of ultra-high resolution microexposure stations. Once such printing station has been developed and implemented at Lawrence Berkeley National Laboratory's Advanced Light Source. This flexible printing station utilizes a programmable coherence illuminator providing real-time pupil-fill control for advanced EUV resist and mask development. The Berkeley exposure system programmable illuminator enables several unique capabilities. Using dipole illumination out to {sigma}=1, the Berkeley tool supports equal-line-space printing down to 12 nm, well beyond the capabilities of similarmore » tools. Using small-sigma illumination combined with the central obscuration of the MET optic enables the system to print feature sizes that are twice as small as those coded on the mask. In this configuration, the effective 10x-demagnification for equal lines and spaces reduces the mask fabrication burden for ultra-high-resolution printing. The illuminator facilitates coherence studies such as the impact of coherence on line-edge roughness (LER) and flare. Finally the illuminator enables novel print-based aberration monitoring techniques as described elsewhere in these proceedings. Here we describe the capabilities of the new MET printing station and present system characterization results. Moreover, we present the latest printing results obtained in experimental resists. Limited by the availability of high-resolution photoresists, equal line-space printing down to 25 nm has been demonstrated as well as isolated line printing down to 29 nm with an LER of approaching 3 nm.« less

A Model For Selecting An Environmentally Responsive Trait: Evaluating Micro-scale Fitness Through UV-C Resistance and Exposure in Escherichia coli.

NASA Astrophysics Data System (ADS)

Schenone, D. J.; Igama, S.; Marash-Whitman, D.; Sloan, C.; Okansinski, A.; Moffet, A.; Grace, J. M.; Gentry, D.

2015-12-01

Experimental evolution of microorganisms in controlled microenvironments serves as a powerful tool for understanding the relationship between micro-scale microbial interactions as well as local-to global-scale environmental factors. In response to iterative and targeted environmental pressures, mutagenesis drives the emergence of novel phenotypes. Current methods to induce expression of these phenotypes require repetitive and time intensive procedures and do not allow for the continuous monitoring of conditions such as optical density, pH and temperature. To address this shortcoming, an Automated Dynamic Directed Evolution Chamber is being developed. It will initially produce Escherichia coli cells with an elevated UV-C resistance phenotype that will ultimately be adapted for different organisms as well as studying environmental effects. A useful phenotype and environmental factor for examining this relationship is UV-C resistance and exposure. In order to build a baseline for the device's operational parameters, a UV-C assay was performed on six E. coli replicates with three exposure fluxes across seven iterations. The fluxes included a 0 second exposure (control), 6 seconds at 3.3 J/m2/s and 40 seconds at 0.5 J/m2/s. After each iteration the cells were regrown and tested for UV-C resistance. We sought to quantify the increase and variability of UV-C resistance among different fluxes, and observe changes in each replicate at each iteration in terms of variance. Under different fluxes, we observed that the 0s control showed no significant increase in resistance, while the 6s/40s fluxes showed increased resistance as the number of iterations increased. A one-million fold increase in survivability was observed after seven iterations. Through statistical analysis using Spearman's rank correlation, the 40s exposure showed signs of more consistently increased resistance, but seven iterations was insufficient to demonstrate statistical significance; to test this further, our experiments will include more iterations. Furthermore, we plan to sequence all the replicants. As adaptation dynamics under intense UV exposure leads to high rate of change, it would be useful to observe differences in tolerance-related and non-tolerance-related genes between the original and UV resistant strains.

Improvement of the efficient referencing and sample positioning system for micro focused synchrotron X-ray techniques

NASA Astrophysics Data System (ADS)

Spangenberg, T.; Göttlicher, J.; Steininger, R.

2016-05-01

An efficient referencing and sample positioning system is a basic tool for a micro focus beamline at a synchrotron. The seven years ago introduced command line based system was upgraded at SUL-X beamline at ANKA [1]. A new combination of current server client techniques offers direct control and facilitates unexperienced users the handling of this frequently used tool.

MicroScope—an integrated microbial resource for the curation and comparative analysis of genomic and metabolic data

PubMed Central

Vallenet, David; Belda, Eugeni; Calteau, Alexandra; Cruveiller, Stéphane; Engelen, Stefan; Lajus, Aurélie; Le Fèvre, François; Longin, Cyrille; Mornico, Damien; Roche, David; Rouy, Zoé; Salvignol, Gregory; Scarpelli, Claude; Thil Smith, Adam Alexander; Weiman, Marion; Médigue, Claudine

2013-01-01

MicroScope is an integrated platform dedicated to both the methodical updating of microbial genome annotation and to comparative analysis. The resource provides data from completed and ongoing genome projects (automatic and expert annotations), together with data sources from post-genomic experiments (i.e. transcriptomics, mutant collections) allowing users to perfect and improve the understanding of gene functions. MicroScope (http://www.genoscope.cns.fr/agc/microscope) combines tools and graphical interfaces to analyse genomes and to perform the manual curation of gene annotations in a comparative context. Since its first publication in January 2006, the system (previously named MaGe for Magnifying Genomes) has been continuously extended both in terms of data content and analysis tools. The last update of MicroScope was published in 2009 in the Database journal. Today, the resource contains data for >1600 microbial genomes, of which ∼300 are manually curated and maintained by biologists (1200 personal accounts today). Expert annotations are continuously gathered in the MicroScope database (∼50 000 a year), contributing to the improvement of the quality of microbial genomes annotations. Improved data browsing and searching tools have been added, original tools useful in the context of expert annotation have been developed and integrated and the website has been significantly redesigned to be more user-friendly. Furthermore, in the context of the European project Microme (Framework Program 7 Collaborative Project), MicroScope is becoming a resource providing for the curation and analysis of both genomic and metabolic data. An increasing number of projects are related to the study of environmental bacterial (meta)genomes that are able to metabolize a large variety of chemical compounds that may be of high industrial interest. PMID:23193269

The combined effects of a monotonous diet and exposure to thiamethoxam on the performance of bumblebee micro-colonies.

PubMed

Dance, C; Botías, C; Goulson, D

2017-05-01

There is a pressing need to better understand the factors contributing to declines of wild pollinators such as bumblebees. Many different contributors have been postulated including: loss of flower-rich habitats and nesting sites; monotonous diets; impacts of invasive pathogens; exposure to pesticides such as neonicotinoids. Past research has tended to investigate the impacts of these stressors in isolation, despite the increasing recognition that bees are simultaneously exposed to a combination of stressors, with potentially additive or synergistic effects. No studies to date have investigated the combined effects of a monotonous diet and exposure to pesticides. Using queenless micro-colonies of Bombus terrestris audax, we examined this interaction by providing bees with monofloral or polyfloral pollen that was either contaminated with field-realistic levels of thiamethoxam, a commonly used neonicotinoid, or not contaminated. Both treatments were found to have a significant effect on various parameters relating to micro-colony performance. Specifically, both pesticide-treated micro-colonies and those fed monofloral pollen grew more slowly than those given polyfloral pollen or pollen without pesticides. The two factors appeared to act additively. Micro-colonies given monofloral pollens also exhibited lower reproductive efforts and produced smaller drones. Although further research is needed to examine whether similar effects are found in whole colonies, these findings increase our understanding of the likely effects of multiple stressors associated with agricultural intensification on bee declines. Copyright © 2017 Elsevier Inc. All rights reserved.

Lower neurocognitive function in U-2 pilots

PubMed Central

Tate, David F.; Wood, Joe; Sladky, John H.; McDonald, Kent; Sherman, Paul M.; Kawano, Elaine S.; Rowland, Laura M.; Patel, Beenish; Wright, Susan N.; Hong, Elliot; Rasmussen, Jennifer; Willis, Adam M.; Kochunov, Peter V.

2014-01-01

Objective: Determine whether United States Air Force (USAF) U-2 pilots (U2Ps) with occupational exposure to repeated hypobaria had lower neurocognitive performance compared to pilots without repeated hypobaric exposure and whether U2P neurocognitive performance correlated with white matter hyperintensity (WMH) burden. Methods: We collected Multidimensional Aptitude Battery–II (MAB-II) and MicroCog: Assessment of Cognitive Functioning (MicroCog) neurocognitive data on USAF U2Ps with a history of repeated occupational exposure to hypobaria and compared these with control data collected from USAF pilots (AFPs) without repeated hypobaric exposure (U2Ps/AFPs MAB-II 87/83; MicroCog 93/80). Additional comparisons were performed between U2Ps with high vs low WMH burden. Results: U2Ps with repeated hypobaric exposure had significantly lower scores than control pilots on reasoning/calculation (U2Ps/AFPs 99.4/106.5), memory (105.5/110.9), information processing accuracy (102.1/105.8), and general cognitive functioning (103.5/108.5). In addition, U2Ps with high whole-brain WMH count showed significantly lower scores on reasoning/calculation (high/low 96.8/104.1), memory (102.9/110.2), general cognitive functioning (101.5/107.2), and general cognitive proficiency (103.6/108.8) than U2Ps with low WMH burden (high/low WMH mean volume 0.213/0.003 cm3 and mean count 14.2/0.4). Conclusion: In these otherwise healthy, highly functioning individuals, pilots with occupational exposure to repeated hypobaria demonstrated lower neurocognitive performance, albeit demonstrable on only some tests, than pilots without repeated exposure. Furthermore, within the U2P population, higher WMH burden was associated with lower neurocognitive test performance. Hypobaric exposure may be a risk factor for subtle changes in neurocognition. PMID:25008397

Nociceptin inhibits vanilloid TRPV-1-mediated neurosensitization induced by fenoterol in human isolated bronchi.

PubMed

Faisy, Christophe; Naline, Emmanuel; Rouget, Céline; Risse, Paul-André; Guerot, Emmanuel; Fagon, Jean-Yves; Chinet, Thierry; Roche, Nicolas; Advenier, Charles

2004-09-01

Chronic exposure to beta(2)-adrenoceptor agonists, especially fenoterol, has been shown to increase smooth muscle contraction to endothelin-1 in human bronchi partly through tachykinin-mediated pathways. The purpose of this work was to further investigate the role of sensory nerves in fenoterol-induced sensitization of human airways and the effect of nociceptin, a nociceptin/orphanin FQ (NOP) receptor agonist, on the increase in contraction after fenoterol exposure. Human bronchi from 62 patients were sensitized to endothelin-1 by prolonged incubation with fenoterol (0.1 microM, 15 h). The sensitizing effect of fenoterol was inhibited by high concentration of capsaicin (10 microM, 30 min before fenoterol sensitization), which induces depletion of mediators from sensory nerves, or co-incubation of fenoterol and capsazepine (1 microM), a vanilloid TRPV-1 receptor antagonist. Moreover, short pretreatment of bronchi with capsaicin (10 microM) or capsazepine (1 microM) after sensitization by fenoterol decreased the rise in smooth muscle contraction to endothelin-1. Nociceptin (1 microM) also inhibited the increased contraction in fenoterol-sensitized bronchi. Tertiapin (10 microM), an inhibitor of the inward-rectifier K(+) channels, but not naloxone (0.1 microM), a DOP/KOP/MOP receptor antagonist, prevented the inhibitory effect of nociceptin. In conclusion, fenoterol induces sensitization of human isolated bronchi to endothelin-1 in part through the stimulation of the vanilloid TRPV-1 receptor on tachykininergic sensory nerves. Nociceptin inhibits airway hyperresponsiveness via NOP receptor activation. This effect involves inward-rectifier K(+) channels.

Urinary 8-hydroxy-2'-deoxyguanosine as a biomarker of oxidative DNA damage in workers exposed to fine particulates.

PubMed

Kim, Jee Young; Mukherjee, Sutapa; Ngo, Long C; Christiani, David C

2004-05-01

Residual oil fly ash (ROFA) is a chemically complex mixture of compounds, including metals that are potentially carcinogenic because of their ability to cause oxidative injury. In this study, we investigated the association between exposure to particulate matter with an aerodynamic mass median diameter

Urinary 8-hydroxy-2'-deoxyguanosine as a biomarker of oxidative DNA damage in workers exposed to fine particulates.

PubMed Central

Kim, Jee Young; Mukherjee, Sutapa; Ngo, Long C; Christiani, David C

2004-01-01

Residual oil fly ash (ROFA) is a chemically complex mixture of compounds, including metals that are potentially carcinogenic because of their ability to cause oxidative injury. In this study, we investigated the association between exposure to particulate matter with an aerodynamic mass median diameter

Indoor transformer stations as predictors of residential ELF magnetic field exposure.

PubMed

Ilonen, K; Markkanen, A; Mezei, G; Juutilainen, Jukka

2008-04-01

Transformer stations in apartment buildings may offer a possibility to conduct epidemiological studies that involve high exposure to extremely low frequency magnetic fields (MF), avoid selection bias and minimize confounding factors. To validate exposure assessment based on transformer stations, measurements were performed in thirty buildings in three Finnish cities. In each building, spot measurements in all rooms and a 24-h recording in a bedroom were performed in one apartment above a transformer station (AAT), in one first floor (FF) reference apartment, and one reference apartment on upper floors (UF). The apartment mean of spot measurements was 0.62 microT in the AATs, 0.21 microT in the FF and 0.11 microT in the UF reference apartments The 24-h apartment mean (estimated from the spot measurements and the bedroom 24-h recording) was 0.2 microT or higher in 29 (97%) AATs, in 7 (25%) FF and in 3 (10 %) UF reference apartments. The corresponding numbers for the 0.4 microT cut-off point were 19 (63%), 4 (14%), and 1 (3.3%). The higher MF level in the FF reference apartments indicates that they should not be considered "unexposed" in epidemiological studies. If such apartments are excluded, a transformer station under the floor predicts 24-h apartment mean MF with a sensitivity of 0.41 (or 0.58) and a specificity of 0.997 (or 0.97), depending on the MF cut-off point (0.2 or 0.4 microT). The results indicate that apartments can be reliably classified as high and low MF field categories based on the known location of transformer stations. (c) 2007 Wiley-Liss, Inc.

Skeletal dosimetry in the MAX06 and the FAX06 phantoms for external exposure to photons based on vertebral 3D-microCT images

NASA Astrophysics Data System (ADS)

Kramer, R.; Khoury, H. J.; Vieira, J. W.; Kawrakow, I.

2006-12-01

3D-microCT images of vertebral bodies from three different individuals have been segmented into trabecular bone, bone marrow and bone surface cells (BSC), and then introduced into the spongiosa voxels of the MAX06 and the FAX06 phantoms, in order to calculate the equivalent dose to the red bone marrow (RBM) and the BSC in the marrow cavities of trabecular bone with the EGSnrc Monte Carlo code from whole-body exposure to external photon radiation. The MAX06 and the FAX06 phantoms consist of about 150 million 1.2 mm cubic voxels each, a part of which are spongiosa voxels surrounded by cortical bone. In order to use the segmented 3D-microCT images for skeletal dosimetry, spongiosa voxels in the MAX06 and the FAX06 phantom were replaced at runtime by so-called micro matrices representing segmented trabecular bone, marrow and BSC in 17.65, 30 and 60 µm cubic voxels. The 3D-microCT image-based RBM and BSC equivalent doses for external exposure to photons presented here for the first time for complete human skeletons are in agreement with the results calculated with the three correction factor method and the fluence-to-dose response functions for the same phantoms taking into account the conceptual differences between the different methods. Additionally the microCT image-based results have been compared with corresponding data from earlier studies for other human phantoms. This article is dedicated to Prof. Dr Guenter Drexler from the Laboratório de Ciências Radiológicas, State University of Rio de Janeiro, on the occasion of his 70th birthday.

Evaluation of a radiation protection cabin for invasive electrophysiological procedures.

PubMed

Dragusin, Octavian; Weerasooriya, Rukshen; Jaïs, Pierre; Hocini, Mélèze; Ector, Joris; Takahashi, Yoshihide; Haïssaguerre, Michel; Bosmans, Hilde; Heidbüchel, Hein

2007-01-01

Complex invasive electrophysiological procedures may result in high cumulative operator radiation exposure. Classical protection with lead aprons results in discomfort while radioprotection is still incomplete. This study evaluated the usefulness of a radiation protection cabin (RPC) that completely surrounds the operator. The evaluation was performed independently in two electrophysiology laboratories (E1-Leuven, Belgium; E2-Bordeaux, France), comparing operator radiation exposure using the RPC vs. a 0.5 mm lead-equivalent apron (total of 135 procedures). E1 used thermoluminiscent dosimeters (TLDs) placed at 16 positions in and out of the RPC and nine positions in and out of the apron. E2 used more sensitive electronic personal dosimeters (EPD), placed at waist and neck. The sensitivity thresholds of the TLDs and EPDs were 10-20 microSv and 1-1.5 microSv, respectively. All procedures could be performed unimpeded with the RPC. Median TLD dose values outside protected areas were in the range of 57-452 microSv, whereas doses under the apron or inside the RPC were all at the background radiation level, irrespective of procedure and fluoroscopy duration and of radiation energy delivered. In addition, the RPC was protecting the entire body (except the hands), whereas lead apron protection is incomplete. Also with the more sensitive EPDs, the radiation dose within the RPC was at the sensitivity threshold/background level (1.3+/-0.6 microSv). Again, radiation to the head was significantly lower within the RPC (1.9+/-1.2 microSv) than with the apron (102+/-23 microSv, P<0.001). The use of the RPC allows performing catheter ablation procedures without compromising catheter manipulation, and with negligible radiation exposure for the operator.

Micro-Analyzer: automatic preprocessing of Affymetrix microarray data.

PubMed

Guzzi, Pietro Hiram; Cannataro, Mario

2013-08-01

A current trend in genomics is the investigation of the cell mechanism using different technologies, in order to explain the relationship among genes, molecular processes and diseases. For instance, the combined use of gene-expression arrays and genomic arrays has been demonstrated as an effective instrument in clinical practice. Consequently, in a single experiment different kind of microarrays may be used, resulting in the production of different types of binary data (images and textual raw data). The analysis of microarray data requires an initial preprocessing phase, that makes raw data suitable for use on existing analysis platforms, such as the TIGR M4 (TM4) Suite. An additional challenge to be faced by emerging data analysis platforms is the ability to treat in a combined way those different microarray formats coupled with clinical data. In fact, resulting integrated data may include both numerical and symbolic data (e.g. gene expression and SNPs regarding molecular data), as well as temporal data (e.g. the response to a drug, time to progression and survival rate), regarding clinical data. Raw data preprocessing is a crucial step in analysis but is often performed in a manual and error prone way using different software tools. Thus novel, platform independent, and possibly open source tools enabling the semi-automatic preprocessing and annotation of different microarray data are needed. The paper presents Micro-Analyzer (Microarray Analyzer), a cross-platform tool for the automatic normalization, summarization and annotation of Affymetrix gene expression and SNP binary data. It represents the evolution of the μ-CS tool, extending the preprocessing to SNP arrays that were not allowed in μ-CS. The Micro-Analyzer is provided as a Java standalone tool and enables users to read, preprocess and analyse binary microarray data (gene expression and SNPs) by invoking TM4 platform. It avoids: (i) the manual invocation of external tools (e.g. the Affymetrix Power Tools), (ii) the manual loading of preprocessing libraries, and (iii) the management of intermediate files, such as results and metadata. Micro-Analyzer users can directly manage Affymetrix binary data without worrying about locating and invoking the proper preprocessing tools and chip-specific libraries. Moreover, users of the Micro-Analyzer tool can load the preprocessed data directly into the well-known TM4 platform, extending in such a way also the TM4 capabilities. Consequently, Micro Analyzer offers the following advantages: (i) it reduces possible errors in the preprocessing and further analysis phases, e.g. due to the incorrect choice of parameters or due to the use of old libraries, (ii) it enables the combined and centralized pre-processing of different arrays, (iii) it may enhance the quality of further analysis by storing the workflow, i.e. information about the preprocessing steps, and (iv) finally Micro-Analzyer is freely available as a standalone application at the project web site http://sourceforge.net/projects/microanalyzer/. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Machine learning for micro-tomography

NASA Astrophysics Data System (ADS)

Parkinson, Dilworth Y.; Pelt, Daniël. M.; Perciano, Talita; Ushizima, Daniela; Krishnan, Harinarayan; Barnard, Harold S.; MacDowell, Alastair A.; Sethian, James

2017-09-01

Machine learning has revolutionized a number of fields, but many micro-tomography users have never used it for their work. The micro-tomography beamline at the Advanced Light Source (ALS), in collaboration with the Center for Applied Mathematics for Energy Research Applications (CAMERA) at Lawrence Berkeley National Laboratory, has now deployed a series of tools to automate data processing for ALS users using machine learning. This includes new reconstruction algorithms, feature extraction tools, and image classification and recommen- dation systems for scientific image. Some of these tools are either in automated pipelines that operate on data as it is collected or as stand-alone software. Others are deployed on computing resources at Berkeley Lab-from workstations to supercomputers-and made accessible to users through either scripting or easy-to-use graphical interfaces. This paper presents a progress report on this work.

Cardiovascular impacts and micro-environmental exposure factors associated with continuous personal PM2.5 monitoring

EPA Science Inventory

The US Environmental Protection Agency’s (US EPA) Detroit Exposure and Aerosol Research Study (DEARS) has provided extensive data on human exposures to a wide variety of air pollutants and their impact on human health. Previous analyses in the DEARS revealed select cardiovascul...

Early and late effects of aspirin and naproxen on microRNAs in the lung and blood of mice, either unexposed or exposed to cigarette smoke

PubMed Central

Izzotti, Alberto; Balansky, Roumen; Ganchev, Gancho; Iltcheva, Marietta; Longobardi, Mariagrazia; Pulliero, Alessandra; Camoirano, Anna; D'Agostini, Francesco; Geretto, Marta; Micale, Rosanna T.; La Maestra, Sebastiano; Miller, Mark Steven; Steele, Vernon E.; De Flora, Silvio

2017-01-01

We recently showed that nonsteroidal anti-inflammatory drugs (NSAIDs) are able to inhibit the lung tumors induced by cigarette smoke, either mainstream (MCS) or environmental (ECS), in female mice. We used subsets of mice to analyze the expression of 1135 microRNAs in both lung and blood serum, as related to the whole-body exposure to smoke and/or oral administration of either aspirin or naproxen. In a first study, we evaluated early microRNA alterations in A/J mice exposed to ECS for 10 weeks, starting at birth, and/or treated with NSAIDs for 6 weeks, starting after weaning. At that time, when no histopathological change were apparent, ECS caused a considerable downregulation of pulmonary microRNAs affecting both adaptive mechanisms and disease-related pathways. Aspirin and naproxen modulated, with intergender differences, the expression of microRNAs having a variety of functions, also including regulation of cyclooxygenases and inflammation. In a second study, we evaluated late microRNA alterations in Swiss H mice exposed to MCS during the first 4 months of life and treated with NSAIDs after weaning until 7.5 months of life, when tumors were detected in mouse lung. Modulation of pulmonary microRNAs by the two NSAIDs was correlated with their ability to prevent preneoplastic lesions (microadenomas) and adenomas in the lung. In both studies, exposure to smoke and/or treatment with NSAIDs also modulated microRNA profiles in the blood serum. However, their levels were poorly correlated with those of pulmonary microRNAs, presumably because circulating microRNAs reflect the contributions from multiple organs and not only from lung. PMID:29156752

Oxygen flux as an indicator of physiological stress in aquatic organisms: a real-time biomonitoring system of water quality

NASA Astrophysics Data System (ADS)

Sanchez, Brian C.; Yale, Gowri; Chatni, Rameez; Ochoa-Acuña, Hugo G.; Porterfield, D. Marshall; Mclamore, Eric S.; Sepúlveda, María S.

2009-05-01

The detection of harmful chemicals and biological agents in real time is a critical need for protecting water quality. We studied the real-time effects of five environmental contaminants with differing modes of action (atrazine, pentachlorophenol, cadmium chloride, malathion, and potassium cyanide) on respiratory oxygen consumption in 2-day post-fertilization fathead minnow (Pimephales promelas) eggs. Our objective was to assess the sensitivity of fathead minnow eggs using the self-referencing micro-optrode technique to detect instantaneous changes in oxygen consumption after brief exposures to low concentrations of contaminants. Oxygen consumption data indicated that the technique is indeed sensitive enough to reliably detect physiological alterations induced by all contaminants. After 2 h of exposure, we identified significant increases in oxygen consumption upon exposure to pentachlorophenol (100 and 1000 μg/L), cadmium chloride (0.0002 and 0.002 μg/L), and atrazine (150 μg/L). In contrast, we observed a significant decrease in oxygen flux after exposures to potassium cyanide (5.2, 22, and 44 μg/L) and atrazine (1500 μg/L). No effects were detected after exposures to malathion (200 and 340 μg/L). We have also tested the sensitivity of Daphnia magna embryos as another animal model for real-time environmental biomonitoring. Our results are so far encouraging and support further development of this technology as a physiologically coupled biomonitoring tool for the detection of environmental toxicants.

Study on Platinum Coating Depth in Focused Ion Beam Diamond Cutting Tool Milling and Methods for Removing Platinum Layer.

PubMed

Choi, Woong Kirl; Baek, Seung Yub

2015-09-22

In recent years, nanomachining has attracted increasing attention in advanced manufacturing science and technologies as a value-added processes to control material structures, components, devices, and nanoscale systems. To make sub-micro patterns on these products, micro/nanoscale single-crystal diamond cutting tools are essential. Popular non-contact methods for the macro/micro processing of diamond composites are pulsed laser ablation (PLA) and electric discharge machining (EDM). However, for manufacturing nanoscale diamond tools, these machining methods are not appropriate. Despite diamond's extreme physical properties, diamond can be micro/nano machined relatively easily using a focused ion beam (FIB) technique. In the FIB milling process, the surface properties of the diamond cutting tool is affected by the amorphous damage layer caused by the FIB gallium ion collision and implantation and these influence the diamond cutting tool edge sharpness and increase the processing procedures. To protect the diamond substrate, a protection layer-platinum (Pt) coating is essential in diamond FIB milling. In this study, the depth of Pt coating layer which could decrease process-induced damage during FIB fabrication is investigated, along with methods for removing the Pt coating layer on diamond tools. The optimum Pt coating depth has been confirmed, which is very important for maintaining cutting tool edge sharpness and decreasing processing procedures. The ultra-precision grinding method and etching with aqua regia method have been investigated for removing the Pt coating layer. Experimental results show that when the diamond cutting tool width is bigger than 500 nm, ultra-precision grinding method is appropriate for removing Pt coating layer on diamond tool. However, the ultra-precision grinding method is not recommended for removing the Pt coating layer when the cutting tool width is smaller than 500 nm, because the possibility that the diamond cutting tool is damaged by the grinding process will be increased. Despite the etching method requiring more procedures to remove the Pt coating layer after FIB milling, it is a feasible method for diamond tools with under 500 nm width.

Environmental Fate and Exposure Assessment for Arsenic in Groundwater (Addendum)

DTIC Science & Technology

2010-06-01

These data suggest that small (perhaps nano -to-micro-meter sized) particles are nucleating on short time scales consistent with overall...perhaps nano -to-micro-meter sized) particles are nucleating on short time scales consistent with overall thermodynamic stability, but that ripening...As was indicative of the final product after aging. These data suggest that small (perhaps nano -to-micro-meter sized) particles are nucleating on

Differential expression of small non-coding RNAs in serum from cattle challenged with viruses causing bovine respiratory disease

USDA-ARS?s Scientific Manuscript database

MicroRNAs and tRNA-derived RNA fragments (tRFs) are the two most abundant groups of small non-coding RNAs. The potential for microRNAs and tRFs to be used as pathogen exposure indicators is yet to be fully explored. Our objective was to identify microRNAs and tRFs in cattle challenged with a non-cy...

A facile and low-cost micro fabrication material: flash foam

PubMed Central

He, Yong; Xiao, Xiao; Wu, Yan; Fu, Jian-zhong

2015-01-01

Although many microfabrication methods have been reported, the preliminary replication templates used in most microfabrication still depend on the expensive and long-period photolithography. This paper explores an alternative replication templates based on a daily used material, flash foam (FF), and proposes a facile microfabrication method, flash foam stamp lithography (FFSL). When FF is exposed with a desired pattern mask, the negative of the pattern is transferred to its surface and micro structures are formed due to the shrinkage of the exposed area. As FF is commonly used in personal stamps, FFSL is very simple and cost-effective. In this paper, we demonstrated that FF is a good and low-cost template for many micro fabrication methods, such as micro casting and soft lithography. Thus, designing and fabricating micro structures at personal office immediately become possible with FFSL. Furthermore, we demonstrated that multi-scale micro structures can be easily fabricated by double exposure with FFSL. Skin textures is used as another case to demonstrate that FFSL can fabricate structures with different depth in a single exposure. As a result, FF shows a promising future in biology, and analytical chemistry, such as rapid fabrication of point of care diagnostics and microfluidic analytical devices with low cost. PMID:26314247

Microscopic dual-energy CT (microDECT): a flexible tool for multichannel ex vivo 3D imaging of biological specimens.

PubMed

Handschuh, S; Beisser, C J; Ruthensteiner, B; Metscher, B D

2017-07-01

Dual-energy computed tomography (DECT) uses two different x-ray energy spectra in order to differentiate between tissues, materials or elements in a single sample or patient. DECT is becoming increasingly popular in clinical imaging and preclinical in vivo imaging of small animal models, but there have been only very few reports on ex vivo DECT of biological samples at microscopic resolutions. The present study has three main aims. First, we explore the potential of microscopic DECT (microDECT) for delivering isotropic multichannel 3D images of fixed biological samples with standard commercial laboratory-based microCT setups at spatial resolutions reaching below 10 μm. Second, we aim for retaining the maximum image resolution and quality during the material decomposition. Third, we want to test the suitability for microDECT imaging of different contrast agents currently used for ex vivo staining of biological samples. To address these aims, we used microCT scans of four different samples stained with x-ray dense contrast agents. MicroDECT scans were acquired with five different commercial microCT scanners from four companies. We present a detailed description of the microDECT workflow, including sample preparation, image acquisition, image processing and postreconstruction material decomposition, which may serve as practical guide for applying microDECT. The MATLAB script (The Mathworks Inc., Natick, MA, USA) used for material decomposition (including a graphical user interface) is provided as a supplement to this paper (https://github.com/microDECT/DECTDec). In general, the presented microDECT workflow yielded satisfactory results for all tested specimens. Original scan resolutions have been mostly retained in the separate material fractions after basis material decomposition. In addition to decomposition of mineralized tissues (inherent sample contrast) and stained soft tissues, we present a case of double labelling of different soft tissues with subsequent material decomposition. We conclude that, in contrast to in vivo DECT examinations, small ex vivo specimens offer some clear advantages regarding technical parameters of the microCT setup and the use of contrast agents. These include a higher flexibility in source peak voltages and x-ray filters, a lower degree of beam hardening due to small sample size, the lack of restriction to nontoxic contrast agents and the lack of a limit in exposure time and radiation dose. We argue that microDECT, because of its flexibility combined with already established contrast agents and the vast number of currently unexploited stains, will in future represent an important technique for various applications in biological research. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Oxygen flux as an indicator of physiological stress in fathead minnow (Pimephales promelas) embryos: a real-time biomonitoring system of water quality.

PubMed

Sanchez, Brian C; Ochoa-Acuña, Hugo; Porterfield, D Marshall; Sepúlveda, María S

2008-09-15

The detection of harmful chemicals and biological agents in real time is a critical need for protecting freshwater ecosystems. We studied the real-time effects of five environmental contaminants with differing modes of action (atrazine, cadmium chloride, pentachlorophenol, malathion, and potassium cyanide) on respiratory oxygen consumption in 2-day postfertilization fathead minnow (Pimephales promelas) eggs. Our objective was to assess the sensitivity of fathead minnow eggs using the self-referencing micro-optrode technique to detect instantaneous changes in oxygen consumption after brief exposures to low concentrations of contaminants. Oxygen consumption data indicated that the technique is indeed sensitive enough to reliably detect physiological alterations induced by four of the five contaminants. After 2 h of exposure, we identified significant increases in oxygen consumption upon exposure to pentachlorophenol (100 and 1000 microg/L), cadmium chloride (0.0002 and 0.002 microg/L), and atrazine (150 microg/L). In contrast, we observed a significant decrease in oxygen flux after exposuresto potassium cyanide (44 and 66 microg/L) and atrazine (1500 microg/L). No effects were detected after exposures to malathion (200 and 340 microg/L). Our work is the first step in development of a new technique for physiologically coupled biomonitoring as a sensitive and reliable tool for the detection of environmental toxicants.

Forensic microradiology: micro-computed tomography (Micro-CT) and analysis of patterned injuries inside of bone.

PubMed

Thali, Michael J; Taubenreuther, Ulrike; Karolczak, Marek; Braun, Marcel; Brueschweiler, Walter; Kalender, Willi A; Dirnhofer, Richard

2003-11-01

When a knife is stabbed in bone, it leaves an impression in the bone. The characteristics (shape, size, etc.) may indicate the type of tool used to produce the patterned injury in bone. Until now it has been impossible in forensic sciences to document such damage precisely and non-destructively. Micro-computed tomography (Micro-CT) offers an opportunity to analyze patterned injuries of tool marks made in bone. Using high-resolution Micro-CT and computer software, detailed analysis of three-dimensional (3D) architecture has recently become feasible and allows microstructural 3D bone information to be collected. With adequate viewing software, data from 2D slice of an arbitrary plane can be extracted from 3D datasets. Using such software as a "digital virtual knife," the examiner can interactively section and analyze the 3D sample. Analysis of the bone injury revealed that Micro-CT provides an opportunity to correlate a bone injury to an injury-causing instrument. Even broken knife tips can be graphically and non-destructively assigned to a suspect weapon.

Microenvironment Tracker (MicroTrac)

EPA Science Inventory

Epidemiologic studies have shown associations between air pollution concentrations measured at central-site ambient monitors and adverse health outcomes. Using central-site concentrations as exposure surrogates, however, can lead to exposure errors due to time spent in various in...

Chronic Ethanol consumption modulates growth factor release, mucosal cytokine production and microRNA expression in nonhuman primates

PubMed Central

Asquith, Mark; Pasala, Sumana; Engelmann, Flora; Haberthur, Kristen; Meyer, Christine; Park, Byung; Grant, Kathleen A.; Messaoudi, Ilhem

2013-01-01

BACKGROUND Chronic alcohol consumption has been associated with enhanced susceptibility to both systemic and mucosal infections. However, the exact mechanisms underlying this enhanced susceptibility remain incompletely understood. METHODS Using a nonhuman primate model of ethanol self-administration, we examined the impact of chronic alcohol exposure on immune homeostasis, cytokine and growth factor production in peripheral blood, lung and intestinal mucosa following twelve months of chronic ethanol exposure. RESULTS Ethanol exposure inhibited activation-induced production of growth factors HGF, G-CSF and VEGF by peripheral blood mononuclear cells (PBMC). Moreover, ethanol significantly reduced the frequency of colonic Th1 and Th17 cells in a dose-dependent manner. In contrast, we did not observe differences in lymphocyte frequency or soluble factor production in the lung of ethanol-consuming animals. To uncover mechanisms underlying reduced growth factor and Th1/Th17 cytokine production, we compared expression levels of microRNAs in PBMC and intestinal mucosa. Our analysis revealed ethanol-dependent upregulation of distinct microRNAs in affected tissues (miR-181a and miR-221 in PBMC; miR-155 in colon). Moreover, we were able to detect reduced expression of the transcription factors STAT3 and ARNT, which regulate expression of VEGF, G-CSF and HGF and contain targets for these microRNAs. To confirm and extend these observations, PBMC were transfected with either mimics or antagomirs of miR181 and 221and protein levels of the transcription factors and growth factors were determined. Transfection of microRNA mimics led to a reduction in both STAT-3/ARNT as well as VEGF/HGF/G-CSF levels. The opposite outcome was observed when microRNA antagomirs were transfected CONCLUSION Chronic ethanol consumption significantly disrupts both peripheral and mucosal immune homeostasis, and this dysregulation may be mediated by changes in microRNA expression. PMID:24329418

Structural coloration of metallic surfaces with micro/nano-structures induced by elliptical vibration texturing

NASA Astrophysics Data System (ADS)

Yang, Yang; Pan, Yayue; Guo, Ping

2017-04-01

Creating orderly periodic micro/nano-structures on metallic surfaces, or structural coloration, for control of surface apparent color and optical reflectivity has been an exciting research topic over the years. The direct applications of structural coloration include color marking, display devices, and invisibility cloak. This paper presents an efficient method to colorize metallic surfaces with periodic micro/nano-gratings using elliptical vibration texturing. When the tool vibration is coupled with a constant cutting velocity, controlled periodic ripples can be generated due to the overlapping tool trajectory. These periodic ripples with a wavelength near visible spectrum can act as micro-gratings to introduce iridescent colors. The proposed technique also provides a flexible method for color marking of metallic surfaces with arbitrary patterns and images by precise control of the spacing distance and orientation of induced micro/nano-ripples. Theoretical analysis and experimental results are given to demonstrate structural coloration of metals by a direct mechanical machining technique.

A microarray for assessing transcription from pelagic marine microbial taxa

PubMed Central

Shilova, Irina N; Robidart, Julie C; James Tripp, H; Turk-Kubo, Kendra; Wawrik, Boris; Post, Anton F; Thompson, Anne W; Ward, Bess; Hollibaugh, James T; Millard, Andy; Ostrowski, Martin; J Scanlan, David; Paerl, Ryan W; Stuart, Rhona; Zehr, Jonathan P

2014-01-01

Metagenomic approaches have revealed unprecedented genetic diversity within microbial communities across vast expanses of the world's oceans. Linking this genetic diversity with key metabolic and cellular activities of microbial assemblages is a fundamental challenge. Here we report on a collaborative effort to design MicroTOOLs (Microbiological Targets for Ocean Observing Laboratories), a high-density oligonucleotide microarray that targets functional genes of diverse taxa in pelagic and coastal marine microbial communities. MicroTOOLs integrates nucleotide sequence information from disparate data types: genomes, PCR-amplicons, metagenomes, and metatranscriptomes. It targets 19 400 unique sequences over 145 different genes that are relevant to stress responses and microbial metabolism across the three domains of life and viruses. MicroTOOLs was used in a proof-of-concept experiment that compared the functional responses of microbial communities following Fe and P enrichments of surface water samples from the North Pacific Subtropical Gyre. We detected transcription of 68% of the gene targets across major taxonomic groups, and the pattern of transcription indicated relief from Fe limitation and transition to N limitation in some taxa. Prochlorococcus (eHLI), Synechococcus (sub-cluster 5.3) and Alphaproteobacteria SAR11 clade (HIMB59) showed the strongest responses to the Fe enrichment. In addition, members of uncharacterized lineages also responded. The MicroTOOLs microarray provides a robust tool for comprehensive characterization of major functional groups of microbes in the open ocean, and the design can be easily amended for specific environments and research questions. PMID:24477198

Insulin stimulation of rat ventricular K+ currents depends on the integrity of the cytoskeleton.

PubMed

Shimoni, Y; Ewart, H S; Severson, D

1999-02-01

1. The effect of insulin on K+ currents was studied with enzymatically dispersed ventricular myocytes from insulin-deficient (type I) diabetic rats. Diabetic conditions were induced by a single intravenous injection of streptozotocin (100 mg kg-1) given 8-13 days before the experiments. Measurements of plasma glucose and insulin levels confirmed the diabetic status of the animals. 2. A Ca2+-independent transient outward K+ current, It, and a slowly inactivating, quasi-steady-state current, Iss, which are depressed in diabetic myocytes, could be restored by exposure to 1, 10 or 100 nM insulin. This was only observed after a delay of 5-6 h, although an insulin exposure of only 1 h was sufficient to initiate its stimulatory action on It and Iss. The stimulatory effect of insulin on these K+ currents was prevented by 2 microM cycloheximide, which in itself had no direct effect on these currents. 3. Disruption of the actin microfilament network with 1 microM cytochalasin D (CD) also prevented the stimulatory effect of 100 nM insulin on both It and Iss. Since CD was added 1 h after insulin, inhibitory effects on insulin signalling were ruled out. Adding CD (1 microM) 5-9 h after insulin, when currents were already augmented, had no effect (up to 50 min exposure). Incubating control cells for 6-10 h with 1 microM CD had no effect on any of the currents measured. 4. Stabilization of the actin network by pre-exposure to 2.5 microM phalloidin restored the stimulatory effect of insulin, in the continued presence of CD, ruling out any effects of CD on components other than the cytoskeleton. 5. The stimulatory effect of insulin was also prevented by incubating cells with insulin in the presence of the microtubule-disrupting agent colchicine (5 microM). 6. These results suggest that the insulin-mediated augmentation of K+ currents in diabetic myocytes requires protein synthesis, possibly of K+ channels, as well as an intact cytoskeleton. The possibility that newly formed channels translocate to the plasma membrane in a process dependent on different elements of the cytoskeleton is discussed.

Human exposure to environmental health concern by types of urban environment: The case of Tel Aviv.

PubMed

Schnell, Izhak; Potchter, Oded; Yaakov, Yaron; Epstein, Yoram

2016-01-01

This study classifies urban environments into types characterized by different exposure to environmental risk factors measured by general sense of discomfort and Heart Rate Variability (HRV). We hypothesize that a set of environmental factors (micro-climatic, CO, noise and individual heart rate) that were measured simultaneously in random locations can provide a better understanding of the distribution of human exposure to environmental loads throughout the urban space than results calculated based on measurements from close fixed stations. We measured micro-climatic and thermal load, CO and noise, individual Heart Rate, Subjective Social Load and Sense of Discomfort (SD) were tested by questionnaire survey. The results demonstrate significant differences in exposure to environmental factors among 8 types of urban environments. It appears that noise and social load are the more significant environmental factors to enhance health risks and general sense of discomfort. Copyright © 2015 Elsevier Ltd. All rights reserved.

Region-of-interest image reconstruction in circular cone-beam microCT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, Seungryong; Bian, Junguo; Pelizzari, Charles A.

2007-12-15

Cone-beam microcomputed tomography (microCT) is one of the most popular choices for small animal imaging which is becoming an important tool for studying animal models with transplanted diseases. Region-of-interest (ROI) imaging techniques in CT, which can reconstruct an ROI image from the projection data set of the ROI, can be used not only for reducing imaging-radiation exposure to the subject and scatters to the detector but also for potentially increasing spatial resolution of the reconstructed images. Increasing spatial resolution in microCT images can facilitate improved accuracy in many assessment tasks. A method proposed previously for increasing CT image spatial resolutionmore » entails the exploitation of the geometric magnification in cone-beam CT. Due to finite detector size, however, this method can lead to data truncation for a large geometric magnification. The Feldkamp-Davis-Kress (FDK) algorithm yields images with artifacts when truncated data are used, whereas the recently developed backprojection filtration (BPF) algorithm is capable of reconstructing ROI images without truncation artifacts from truncated cone-beam data. We apply the BPF algorithm to reconstructing ROI images from truncated data of three different objects acquired by our circular cone-beam microCT system. Reconstructed images by use of the FDK and BPF algorithms from both truncated and nontruncated cone-beam data are compared. The results of the experimental studies demonstrate that, from certain truncated data, the BPF algorithm can reconstruct ROI images with quality comparable to that reconstructed from nontruncated data. In contrast, the FDK algorithm yields ROI images with truncation artifacts. Therefore, an implication of the studies is that, when truncated data are acquired with a configuration of a large geometric magnification, the BPF algorithm can be used for effective enhancement of the spatial resolution of a ROI image.« less

EUV lithography for 30nm half pitch and beyond: exploring resolution, sensitivity, and LWR tradeoffs

NASA Astrophysics Data System (ADS)

Putna, E. Steve; Younkin, Todd R.; Chandhok, Manish; Frasure, Kent

2009-03-01

The International Technology Roadmap for Semiconductors (ITRS) denotes Extreme Ultraviolet (EUV) lithography as a leading technology option for realizing the 32nm half-pitch node and beyond. Readiness of EUV materials is currently one high risk area according to assessments made at the 2008 EUVL Symposium. The main development issue regarding EUV resist has been how to simultaneously achieve high sensitivity, high resolution, and low line width roughness (LWR). This paper describes the strategy and current status of EUV resist development at Intel Corporation. Data is presented utilizing Intel's Micro-Exposure Tool (MET) examining the feasibility of establishing a resist process that simultaneously exhibits <=30nm half-pitch (HP) L/S resolution at <=10mJ/cm2 with <=4nm LWR.

EUV lithography for 22nm half pitch and beyond: exploring resolution, LWR, and sensitivity tradeoffs

NASA Astrophysics Data System (ADS)

Putna, E. Steve; Younkin, Todd R.; Caudillo, Roman; Chandhok, Manish

2010-04-01

The International Technology Roadmap for Semiconductors (ITRS) denotes Extreme Ultraviolet (EUV) lithography as a leading technology option for realizing the 22nm half pitch node and beyond. Readiness of EUV materials is currently one high risk area according to recent assessments made at the 2009 EUVL Symposium. The main development issue regarding EUV resist has been how to simultaneously achieve high sensitivity, high resolution, and low line width roughness (LWR). This paper describes the strategy and current status of EUV resist development at Intel Corporation. Data collected utilizing Intel's Micro-Exposure Tool (MET) is presented in order to examine the feasibility of establishing a resist process that simultaneously exhibits <=22nm half-pitch (HP) L/S resolution at <= 12.5mJ/cm2 with <= 4nm LWR.

GPS-based Microenvironment Tracker (MicroTrac) Model to Estimate Time-Location of Individuals for Air Pollution Exposure Assessments: Model Evaluation in Central North Carolina

EPA Science Inventory

A critical aspect of air pollution exposure assessment is the estimation of the time spent by individuals in various microenvironments (ME). Accounting for the time spent in different ME with different pollutant concentrations can reduce exposure misclassifications, while failure...

Regularly scheduled, day-time, slow-onset 60 Hz electric and magnetic field exposure does not depress serum melatonin concentration in nonhuman primates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rogers, W.R.; Smith, H.D.; Orr, J.L.

Experiments conducted with laboratory rodents indicate that exposure to 60 Hz electric fields or magnetic fields can suppress nocturnal melatonin concentrations in pineal gland and blood. In three experiments employing three field-exposed and three sham-exposed nonhuman primates, each implanted with an indwelling venous cannula to allow repeated blood sampling, the authors studied the effects of either 6 kV/m and 50 {micro}T (0.5 G) or 30 kV/m and 100 {micro}T (1.0 G) on serum melatonin patterns. The fields were ramped on and off slowly, so that no transients occurred. Extensive quality control for the melatonin assay, computerized control and monitoring ofmore » field intensities, and consistent exposure protocols were used. No changes in nocturnal serum melatonin concentration resulted from 6 weeks of day-time exposure with slow field onset/offset and a highly regular exposure protocol. These results indicate that, under the conditions tested, day-time exposure to 60 Hz electric and magnetic fields in combination does not result in melatonin suppression in primates.« less

Patterning highly ordered arrays of complex nanofeatures through EUV directed polarity switching of non chemically amplified photoresist

PubMed Central

Ghosh, Subrata; Satyanarayana, V. S. V.; Pramanick, Bulti; Sharma, Satinder K.; Pradeep, Chullikkattil P.; Morales-Reyes, Israel; Batina, Nikola; Gonsalves, Kenneth E.

2016-01-01

Given the importance of complex nanofeatures in the filed of micro-/nanoelectronics particularly in the area of high-density magnetic recording, photonic crystals, information storage, micro-lens arrays, tissue engineering and catalysis, the present work demonstrates the development of new methodology for patterning complex nanofeatures using a recently developed non-chemically amplified photoresist (n-CARs) poly(4-(methacryloyloxy)phenyl)dimethylsulfoniumtriflate) (polyMAPDST) with the help of extreme ultraviolet lithography (EUVL) as patterning tool. The photosensitivity of polyMAPDST is mainly due to the presence of radiation sensitive trifluoromethanesulfonate unit (triflate group) which undergoes photodegradation upon exposure with EUV photons, and thus brings in polarity change in the polymer structure. Integration of such radiation sensitive unit into polymer network avoids the need of chemical amplification which is otherwise needed for polarity switching in the case of chemically amplified photoresists (CARs). Indeed, we successfully patterned highly ordered wide-raging dense nanofeatures that include nanodots, nanowaves, nanoboats, star-elbow etc. All these developed nanopatterns have been well characterized by FESEM and AFM techniques. Finally, the potential of polyMAPDST has been established by successful transfer of patterns into silicon substrate through adaptation of compatible etch recipes. PMID:26975782

Morphine, but not sodium cromoglycate, modulates the release of substance P from capsaicin-sensitive neurones in the rat trachea in vitro.

PubMed Central

Ray, N. J.; Jones, A. J.; Keen, P.

1991-01-01

1. Opioids have been shown to inhibit substance P (SP) release from primary afferent neurones (PAN). In addition, opioid receptors have been identified on PAN of the vagus nerves. Sodium cromoglycate (SCG) decreases the excitability of C-fibres in the lung of the dog in vivo. We have utilised a multi-superfusion system to investigate the effect of opioids and SCG on the release of SP from the rat trachea in vitro. 2. Pretreatment of newborn rats with capsaicin (50 mg kg-1 s.c. at day 1 and 2 of life) resulted in a 93.2 +/- 6.3% reduction in tracheal substance P-like immunoreactivity (SP-LI) content when determined by radioimmunoassay in the adult. 3. Exposure to isotonically elevated potassium concentrations (37-90 mM), capsaicin (100 nM-10 microM), and bradykinin (BK; 10nm-1 microM) but not des-Arg9-BK (1 microM) stimulated SP-LI release by a calcium-dependent mechanism. 4. SCG (1 microM and 100 microM) did not affect spontaneous, potassium (60 mM)- or BK (1 microM)-stimulated SP-LI release. 5. Morphine (0.1-100 microM) caused dose-related inhibition of potassium (60 mM)-stimulated SP-LI release with the greatest inhibition of 60.4 +/- 13.7% at 100 microM. The effect of morphine was not mimicked by the kappa-opioid receptor agonist, U50,488H (10 microM) or the delta-opioid receptor agonist, Tyr-(D-Pen)-Gly-Phe-(D-Pen) (DPDPE). 6. The effect of morphine was totally abolished by prior and concomitant exposure to naloxone (100 nM) which had no effect on control release values.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1713104

Organophosphorus pesticide exposure of urban and suburban preschool children with organic and conventional diets.

PubMed Central

Curl, Cynthia L; Fenske, Richard A; Elgethun, Kai

2003-01-01

We assessed organophosphorus (OP) pesticide exposure from diet by biological monitoring among Seattle, Washington, preschool children. Parents kept food diaries for 3 days before urine collection, and they distinguished organic and conventional foods based on label information. Children were then classified as having consumed either organic or conventional diets based on analysis of the diary data. Residential pesticide use was also recorded for each home. We collected 24-hr urine samples from 18 children with organic diets and 21 children with conventional diets and analyzed them for five OP pesticide metabolites. We found significantly higher median concentrations of total dimethyl alkylphosphate metabolites than total diethyl alkylphosphate metabolites (0.06 and 0.02 micro mol/L, respectively; p = 0.0001). The median total dimethyl metabolite concentration was approximately six times higher for children with conventional diets than for children with organic diets (0.17 and 0.03 micro mol/L; p = 0.0003); mean concentrations differed by a factor of nine (0.34 and 0.04 micro mol/L). We calculated dose estimates from urinary dimethyl metabolites and from agricultural pesticide use data, assuming that all exposure came from a single pesticide. The dose estimates suggest that consumption of organic fruits, vegetables, and juice can reduce children's exposure levels from above to below the U.S. Environmental Protection Agency's current guidelines, thereby shifting exposures from a range of uncertain risk to a range of negligible risk. Consumption of organic produce appears to provide a relatively simple way for parents to reduce their children's exposure to OP pesticides. PMID:12611667

Magnetic field exposure and behavioral monitoring system.

PubMed

Thomas, A W; Drost, D J; Prato, F S

2001-09-01

To maximize the availability and usefulness of a small magnetic field exposure laboratory, we designed a magnetic field exposure system that has been used to test human subjects, caged or confined animals, and cell cultures. The magnetic field exposure system consists of three orthogonal pairs of coils 2 m square x 1 m separation, 1.751 m x 0.875 m separation, and 1.5 m x 0.75 m separation. Each coil consisted of ten turns of insulated 8 gauge stranded copper conductor. Each of the pairs were driven by a constant-current amplifier via digital to analog (D/A) converter. A 9 pole zero-gain active Bessel low-pass filter (1 kHz corner frequency) before the amplifier input attenuated the expected high frequencies generated by the D/A conversion. The magnetic field was monitored with a 3D fluxgate magnetometer (0-3 kHz, +/- 1 mT) through an analog to digital converter. Behavioral monitoring utilized two monochrome video cameras (viewing the coil center vertically and horizontally), both of which could be video recorded and real-time digitally Moving Picture Experts Group (MPEG) encoded to CD-ROM. Human postural sway (standing balance) was monitored with a 3D forceplate mounted on the floor, connected to an analog to digital converter. Lighting was provided by 12 offset overhead dimmable fluorescent track lights and monitored using a digitally connected spectroradiometer. The dc resistance, inductance of each coil pair connected in series were 1.5 m coil (0.27 Omega, 1.2 mH), 1.75 m coil (0.32 Omega, 1.4 mH), and 2 m coil (0.38 Omega, 1.6 mH). The frequency response of the 1.5 m coil set was 500 Hz at +/- 463 microT, 1 kHz at +/- 232 microT, 150 micros rise time from -200 microT(pk) to + 200 microT(pk) (square wave) and is limited by the maximum voltage ( +/- 146 V) of the amplifier (Bessel filter bypassed). Copyright 2001 Wiley-Liss, Inc.

Cancer risks associated with occupational exposure to magnetic fields among electric utility workers in Ontario and Quebec, Canada, and France: 1970-1989.

PubMed

Thériault, G; Goldberg, M; Miller, A B; Armstrong, B; Guénel, P; Deadman, J; Imbernon, E; To, T; Chevalier, A; Cyr, D

1994-03-15

To determine whether occupational exposure to magnetic fields of 50-60 Hz was associated with cancer among electric utility workers, the authors used a case-control design nested within three cohorts of workers at electric utilities: Electricité de France--Gaz de France, 170,000 men; Ontario Hydro, 31,543 men; and Hydro-Québec, 21,749 men. During the observation period, 1970-1989, 4,151 new cases of cancer occurred. Each participant's cumulative exposure to magnetic fields was estimated based on measurements of current exposure of 2,066 workers performing tasks similar to those in the cohorts using personal dosimetry. Estimates were also made of past exposure based on knowledge of current loading, work practices, and usage. Workers who had more than the median cumulative exposure to magnetic fields (3.1 microtesla (microT)-years) had a higher risk for acute nonlymphoid leukemia (odds ratio (OR) = 2.41, 95% confidence interval (CI) 1.07-5.44). The same observation holds for acute myeloid leukemia (OR = 3.15, 95% CI 1.20-8.27). There was also an elevated risk for mean exposure above 0.2 microT (acute nonlymphoid leukemia, OR = 2.36, 95% CI 1.00-5.58; acute myeloid leukemia, OR = 2.25, 95% CI 0.79-6.46). However, there were no clear dose-response trends with increasing exposure and no consistency among the three utilities. Men whose cumulative exposure to magnetic fields was above the 90th percentile (15.7 microT-years) had an elevated risk for brain cancer (OR = 1.95, 95% CI 0.76-5.00) that was not statistically significant. No association with magnetic fields was observed for any of the other 29 types of cancer studied, including skin melanoma, male breast cancer, and prostate cancer. Controlling for potential confounding factors did not change the results.

MicrO: an ontology of phenotypic and metabolic characters, assays, and culture media found in prokaryotic taxonomic descriptions.

PubMed

Blank, Carrine E; Cui, Hong; Moore, Lisa R; Walls, Ramona L

2016-01-01

MicrO is an ontology of microbiological terms, including prokaryotic qualities and processes, material entities (such as cell components), chemical entities (such as microbiological culture media and medium ingredients), and assays. The ontology was built to support the ongoing development of a natural language processing algorithm, MicroPIE (or, Microbial Phenomics Information Extractor). During the MicroPIE design process, we realized there was a need for a prokaryotic ontology which would capture the evolutionary diversity of phenotypes and metabolic processes across the tree of life, capture the diversity of synonyms and information contained in the taxonomic literature, and relate microbiological entities and processes to terms in a large number of other ontologies, most particularly the Gene Ontology (GO), the Phenotypic Quality Ontology (PATO), and the Chemical Entities of Biological Interest (ChEBI). We thus constructed MicrO to be rich in logical axioms and synonyms gathered from the taxonomic literature. MicrO currently has ~14550 classes (~2550 of which are new, the remainder being microbiologically-relevant classes imported from other ontologies), connected by ~24,130 logical axioms (5,446 of which are new), and is available at (http://purl.obolibrary.org/obo/MicrO.owl) and on the project website at https://github.com/carrineblank/MicrO. MicrO has been integrated into the OBO Foundry Library (http://www.obofoundry.org/ontology/micro.html), so that other ontologies can borrow and re-use classes. Term requests and user feedback can be made using MicrO's Issue Tracker in GitHub. We designed MicrO such that it can support the ongoing and future development of algorithms that can leverage the controlled vocabulary and logical inference power provided by the ontology. By connecting microbial classes with large numbers of chemical entities, material entities, biological processes, molecular functions, and qualities using a dense array of logical axioms, we intend MicrO to be a powerful new tool to increase the computing power of bioinformatics tools such as the automated text mining of prokaryotic taxonomic descriptions using natural language processing. We also intend MicrO to support the development of new bioinformatics tools that aim to develop new connections between microbial phenotypes and genotypes (i.e., the gene content in genomes). Future ontology development will include incorporation of pathogenic phenotypes and prokaryotic habitats.

Micro and nanotechnology for biological and biomedical applications.

PubMed

Lim, Chwee Teck; Han, Jongyoon; Guck, Jochen; Espinosa, Horacio

2010-10-01

This special issue contains some of the current state-of-the-art development and use of micro and nanotechnological tools, devices and techniques for both biological and biomedical research and applications. These include nanoparticles for bioimaging and biosensing, optical and biophotonic techniques for probing diseases at the nanoscale, micro and nano-fabricated tools for elucidating molecular mechanisms of mechanotransduction in cell and molecular biology and cell separation microdevices and techniques for isolating and enriching targeted cells for disease detection and diagnosis. Although some of these works are still at the research stage, there is no doubt that some of the important outcomes will eventually see actual biomedical applications in the not too distant future.

A novel AFM-based 5-axis nanoscale machine tool for fabrication of nanostructures on a micro ball

NASA Astrophysics Data System (ADS)

Geng, Yanquan; Wang, Yuzhang; Yan, Yongda; Zhao, Xuesen

2017-11-01

This paper presents a novel atomic force microscopy (AFM)-based 5-axis nanoscale machine tool developed to fabricate nanostructures on different annuli of the micro ball. Different nanostructures can be obtained by combining the scratching trajectory of the AFM tip with the movement of the high precision air-bearing spindle. The center of the micro ball is aligned to be coincided with the gyration center of the high precision to guarantee the machining process during the rotating of the air-bearing spindle. Processing on different annuli of the micro ball is achieved by controlling the distance between the center of the micro ball and the rotation center of the AFM head. Nanostructures including square cavities, circular cavities, triangular cavities, and an annular nanochannel are machined successfully on the three different circumferences of a micro ball with a diameter of 1500 μm. Moreover, the influences of the error motions of the high precision air-bearing spindle and the eccentric between the micro ball and the gyration center of the high precision air-bearing spindle on the processing position error on the micro ball are also investigated. This proposed machining method has the potential to prepare the inertial confinement fusion target with the expected dimension defects, which would advance the application of the AFM tip-based nanomachining approach.

Cl- channel blockers NPPB and niflumic acid blunt Ca(2+)-induced erythrocyte 'apoptosis'.

PubMed

Myssina, Svetlana; Lang, Philipp A; Kempe, Daniela S; Kaiser, Stefanie; Huber, Stephan M; Wieder, Thomas; Lang, Florian

2004-01-01

Exposure to Ca2+ ionophore ionomycin, osmotic shock, oxidative stress and glucose depletion trigger cell shrinkage and scramblase-mediated phosphatidylserine exposure at the outer leaflet of the erythrocyte cell membrane. The effects are partially due to activation of GARDOS channels and subsequent cellular K+ loss leading not only to cell shrinkage but also participating in the triggering of erythrocyte scramblase. As conductive loss of K+ would depend on the parallel loss of anions we hypothesised that activation of scramblase is similarly dependent on the activity of Cl- channels. To test this hypothesis, we used Cl- channel blockers NPPB and niflumic acid. It is shown here that treatment of erythrocytes with 1 microM ionomycin leads to cellular K+ loss, decrease of hematocrit and decrease of forward scatter in FACS analysis reflecting cell shrinkage as well as increase of annexin positive cells reflecting phosphatidylserine exposure. Those events were significantly blunted in the presence of 100 microM NPPB by 34% (K+ loss), 45% (hematocrit), 32% (forward scatter) and 69% (annexin binding), or in the presence of 100 microM niflumic acid by 15% (forward scatter) and 45% (annexin binding), respectively. Moreover, oxidative stress triggered annexin binding which was again significantly inhibited (by 51%) in the presence of 100 microM NPPB. In conclusion, Cl- channels presumably participate in the regulation of erythrocyte 'apoptosis'. Copyright 2004 S. Karger AG, Basel

Simultaneous optimization of micro-heliostat geometry and field layout using a genetic algorithm

NASA Astrophysics Data System (ADS)

Lazardjani, Mani Yousefpour; Kronhardt, Valentina; Dikta, Gerhard; Göttsche, Joachim

2016-05-01

A new optimization tool for micro-heliostat (MH) geometry and field layout is presented. The method intends simultaneous performance improvement and cost reduction through iteration of heliostat geometry and field layout parameters. This tool was developed primarily for the optimization of a novel micro-heliostat concept, which was developed at Solar-Institut Jülich (SIJ). However, the underlying approach for the optimization can be used for any heliostat type. During the optimization the performance is calculated using the ray-tracing tool SolCal. The costs of the heliostats are calculated by use of a detailed cost function. A genetic algorithm is used to change heliostat geometry and field layout in an iterative process. Starting from an initial setup, the optimization tool generates several configurations of heliostat geometries and field layouts. For each configuration a cost-performance ratio is calculated. Based on that, the best geometry and field layout can be selected in each optimization step. In order to find the best configuration, this step is repeated until no significant improvement in the results is observed.

Modulation of mesenchymal stem cell behavior by nano- and micro-sized β-tricalcium phosphate particles in suspension and composite structures

NASA Astrophysics Data System (ADS)

Smoak, Mollie; Hogan, Katie; Kriegh, Lisa; Chen, Cong; Terrell, LeKeith B.; Qureshi, Ammar T.; Todd Monroe, W.; Gimble, Jeffrey M.; Hayes, Daniel J.

2015-04-01

Interest has grown in the use of microparticles and nanoparticles for modifying the mechanical and biological properties of synthetic bone composite structures. Micro- and nano-sized calcium phosphates are of interest for their osteoinductive behavior. Engineered composites incorporating polymers and ceramics, such as poly-l-lactic acid (PLLA) and beta-tricalcium phosphate (β-TCP), for bone tissue regeneration have been well investigated for their proliferative and osteoinductive abilities. Only limited research has been done to investigate the effects of different sizes of β-TCP particles on human mesenchymal stromal cell behavior. As such, the aim of this study was to investigate the modulations of human adipose-derived stem cell (hASCs) behavior within cell/particle and cell/composite systems as functions of particle size, concentration, and exposure time. The incorporation of nanoscale calcium phosphate resulted in improved mechanical properties and osteogenic behavior within the scaffold compared to the microscale calcium phosphate additives. Particle exposure results indicate that cytotoxicity on hASCs correlates inversely with particle size and increases with the increasing exposure time and particle concentration. Composites with increasing β-TCP content, whether microparticles or nanoparticles, were less toxic than colloidal micro- and nano-sized β-TCP particles directly supplied to hASCs. The difference in viability observed as a result of varying exposure route is likely related to the increased cell-particle interactions in the direct exposure compared to the particles becoming trapped within the scaffold/polymer matrix.

Calculating radiation exposures during use of (14)C-labeled nutrients, food components, and biopharmaceuticals to quantify metabolic behavior in humans.

PubMed

Kim, Seung-Hyun; Kelly, Peter B; Clifford, Andrew J

2010-04-28

(14)C has long been used as a tracer for quantifying the in vivo human metabolism of food components, biopharmaceuticals, and nutrients. Minute amounts (< or =1 x 10 (-18) mol) of (14)C can be measured with high-throughput (14)C-accelerator mass spectrometry (HT (14)C-AMS) in isolated chemical extracts of biological, biomedical, and environmental samples. Availability of in vivo human data sets using a (14)C tracer would enable current concepts of the metabolic behavior of food components, biopharmaceuticals, or nutrients to be organized into models suitable for quantitative hypothesis testing and determination of metabolic parameters. In vivo models are important for specification of intake levels for food components, biopharmaceuticals, and nutrients. Accurate estimation of the radiation exposure from ingested (14)C is an essential component of the experimental design. Therefore, this paper illustrates the calculation involved in determining the radiation exposure from a minute dose of orally administered (14)C-beta-carotene, (14)C-alpha-tocopherol, (14)C-lutein, and (14)C-folic acid from four prior experiments. The administered doses ranged from 36 to 100 nCi, and radiation exposure ranged from 0.12 to 5.2 microSv to whole body and from 0.2 to 3.4 microSv to liver with consideration of tissue weighting factor and fractional nutrient. In comparison, radiation exposure experienced during a 4 h airline flight across the United States at 37000 ft was 20 microSv.

MicroRNAfold: pre-microRNA secondary structure prediction based on modified NCM model with thermodynamics-based scoring strategy.

PubMed

Han, Dianwei; Zhang, Jun; Tang, Guiliang

2012-01-01

An accurate prediction of the pre-microRNA secondary structure is important in miRNA informatics. Based on a recently proposed model, nucleotide cyclic motifs (NCM), to predict RNA secondary structure, we propose and implement a Modified NCM (MNCM) model with a physics-based scoring strategy to tackle the problem of pre-microRNA folding. Our microRNAfold is implemented using a global optimal algorithm based on the bottom-up local optimal solutions. Our experimental results show that microRNAfold outperforms the current leading prediction tools in terms of True Negative rate, False Negative rate, Specificity, and Matthews coefficient ratio.

Local x-ray structure analysis of optically manipulated biological micro-objects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cojoc, Dan; Ferrari, Enrico; Santucci, Silvia C.

2010-12-13

X-ray diffraction using micro- and nanofocused beams is well suited for nanostructure analysis at different sites of a biological micro-object. To conduct in vitro studies without mechanical contact, we developed object manipulation by optical tweezers in a microfluidic cell. Here we report x-ray microdiffraction analysis of a micro-object optically trapped in three dimensions. We revealed the nanostructure of a single starch granule at different points and investigated local radiation damage induced by repeated x-ray exposures at the same position, demonstrating high stability and full control of the granule orientation by multiple optical traps.

Micro Autonomous Systems Research: Systems Engineering Processes for Micro Autonomous Systems

DTIC Science & Technology

2016-11-01

product family design and reconfigurable system design with recent developments in the fields of automated manufacturing and micro-autonomous...mapped to design parameters. These mappings are the mechanism by which physical product designs are formulated. Finally, manufacture of the product ... design tools and manufacturing and testing the resulting design . The final products were inspected and flight tested so that their

Development of Micro-Electrode Array Based Tests for Neurotoxicity: Assessment of Interlaboratory Reproducibility with Neuroactive Chemicals

PubMed Central

Novellino, A.; Scelfo, Bibiana; Palosaari, T.; Price, A.; Sobanski, Tomasz; Shafer, T. J.; Johnstone, A. F. M.; Gross, G. W.; Gramowski, A.; Schroeder, O.; Jügelt, K.; Chiappalone, M.; Benfenati, F.; Martinoia, S.; Tedesco, M. T.; Defranchi, E.; D’Angelo, P.; Whelan, M.

2011-01-01

Neuronal assemblies within the nervous system produce electrical activity that can be recorded in terms of action potential patterns. Such patterns provide a sensitive endpoint to detect effects of a variety of chemical and physical perturbations. They are a function of synaptic changes and do not necessarily involve structural alterations. In vitro neuronal networks (NNs) grown on micro-electrode arrays (MEAs) respond to neuroactive substances as well as the in vivo brain. As such, they constitute a valuable tool for investigating changes in the electrophysiological activity of the neurons in response to chemical exposures. However, the reproducibility of NN responses to chemical exposure has not been systematically documented. To this purpose six independent laboratories (in Europe and in USA) evaluated the response to the same pharmacological compounds (Fluoxetine, Muscimol, and Verapamil) in primary neuronal cultures. Common standardization principles and acceptance criteria for the quality of the cultures have been established to compare the obtained results. These studies involved more than 100 experiments before the final conclusions have been drawn that MEA technology has a potential for standard in vitro neurotoxicity/neuropharmacology evaluation. The obtained results show good intra- and inter-laboratory reproducibility of the responses. The consistent inhibitory effects of the compounds were observed in all the laboratories with the 50% Inhibiting Concentrations (IC50s) ranging from: (mean ± SEM, in μM) 1.53 ± 0.17 to 5.4 ± 0.7 (n = 35) for Fluoxetine, 0.16 ± 0.03 to 0.38 ± 0.16 μM (n = 35) for Muscimol, and 2.68 ± 0.32 to 5.23 ± 1.7 (n = 32) for Verapamil. The outcome of this study indicates that the MEA approach is a robust tool leading to reproducible results. The future direction will be to extend the set of testing compounds and to propose the MEA approach as a standard screen for identification and prioritization of chemicals with neurotoxicity potential. PMID:21562604

Common features of microRNA target prediction tools

PubMed Central

Peterson, Sarah M.; Thompson, Jeffrey A.; Ufkin, Melanie L.; Sathyanarayana, Pradeep; Liaw, Lucy; Congdon, Clare Bates

2014-01-01

The human genome encodes for over 1800 microRNAs (miRNAs), which are short non-coding RNA molecules that function to regulate gene expression post-transcriptionally. Due to the potential for one miRNA to target multiple gene transcripts, miRNAs are recognized as a major mechanism to regulate gene expression and mRNA translation. Computational prediction of miRNA targets is a critical initial step in identifying miRNA:mRNA target interactions for experimental validation. The available tools for miRNA target prediction encompass a range of different computational approaches, from the modeling of physical interactions to the incorporation of machine learning. This review provides an overview of the major computational approaches to miRNA target prediction. Our discussion highlights three tools for their ease of use, reliance on relatively updated versions of miRBase, and range of capabilities, and these are DIANA-microT-CDS, miRanda-mirSVR, and TargetScan. In comparison across all miRNA target prediction tools, four main aspects of the miRNA:mRNA target interaction emerge as common features on which most target prediction is based: seed match, conservation, free energy, and site accessibility. This review explains these features and identifies how they are incorporated into currently available target prediction tools. MiRNA target prediction is a dynamic field with increasing attention on development of new analysis tools. This review attempts to provide a comprehensive assessment of these tools in a manner that is accessible across disciplines. Understanding the basis of these prediction methodologies will aid in user selection of the appropriate tools and interpretation of the tool output. PMID:24600468

Common features of microRNA target prediction tools.

PubMed

Peterson, Sarah M; Thompson, Jeffrey A; Ufkin, Melanie L; Sathyanarayana, Pradeep; Liaw, Lucy; Congdon, Clare Bates

2014-01-01

The human genome encodes for over 1800 microRNAs (miRNAs), which are short non-coding RNA molecules that function to regulate gene expression post-transcriptionally. Due to the potential for one miRNA to target multiple gene transcripts, miRNAs are recognized as a major mechanism to regulate gene expression and mRNA translation. Computational prediction of miRNA targets is a critical initial step in identifying miRNA:mRNA target interactions for experimental validation. The available tools for miRNA target prediction encompass a range of different computational approaches, from the modeling of physical interactions to the incorporation of machine learning. This review provides an overview of the major computational approaches to miRNA target prediction. Our discussion highlights three tools for their ease of use, reliance on relatively updated versions of miRBase, and range of capabilities, and these are DIANA-microT-CDS, miRanda-mirSVR, and TargetScan. In comparison across all miRNA target prediction tools, four main aspects of the miRNA:mRNA target interaction emerge as common features on which most target prediction is based: seed match, conservation, free energy, and site accessibility. This review explains these features and identifies how they are incorporated into currently available target prediction tools. MiRNA target prediction is a dynamic field with increasing attention on development of new analysis tools. This review attempts to provide a comprehensive assessment of these tools in a manner that is accessible across disciplines. Understanding the basis of these prediction methodologies will aid in user selection of the appropriate tools and interpretation of the tool output.

Characteristics and formation mechanism for stainless steel fiber with periodic micro-fins

NASA Astrophysics Data System (ADS)

Tang, Tao; Wan, Zhenping; Lu, Longsheng; Tang, Yong

2016-05-01

Metal fibers have been widely used in many industrial applications due to their unique advantages. In certain applications, such as catalyst supports or orthopedic implants, a rough surface or tiny outshoots on the surface of metal fibers to increase surface area are needed. However, it has not been concerned about the surface morphologies of metal fiber in the current research of metal fiber manufacturing. In this paper, a special multi-tooth tool composed of a row of triangular tiny teeth is designed. The entire cutting layer of multi-tooth tool bifurcates into several thin cutting layers due to tiny teeth involved in cutting. As a result, several stainless steel fibers with periodic micro-fins are produced simultaneously. Morphology of periodic micro-fins is found to be diverse and can be classified into three categories: unilateral plane, unilateral tapering and bilateral. There are two forming mechanisms for the micro-fins. One is that periodic burrs remained on the free side of cutting layer of a tiny tooth create micro-fins of stainless steel fiber produced by the next neighboring tiny tooth; the other is that the connections between two fibers stuck together come to be micro-fins if the two fibers are finally detached. Influence of cutting conditions on formation of micro-fins is investigated. Experimental results show that cutting depth has no significant effect on micro-fin formation, high cutting speed is conducive to micro-fin formation, and feed should be between 0.12 mm/r and 0.2 mm/r to reliably obtain stainless steel fiber with micro-fins. This research presents a new pattern of stainless steel fiber characterized by periodic micro-fins formed on the edge of fiber and its manufacturing method.

Photo-oxidative degradation of motorcycle helmets in Hanoi, Vietnam: A prospective preliminary study.

PubMed

Ramli, Roszalina; Che Man, Zuraidah; Nordin, Rifqah; Abdul Karim, Fadzlina; Rashdi, Muhd Fazlynizam; Oxley, Jennie; Viet Cuong, Pham

2016-09-01

Vietnamese spend hours travelling on the road using their motorcycles. Their helmets are exposed continuously to sunlight and rain. The objectives of this study were to determine the association between the effect of photo-oxidative degradation (POD) of the outer shells and helmet age on helmet damage. The micro-structural change of the outer shell was also investigated. This was a prospective, cross sectional study recruiting injured motorcyclists from Hanoi, Vietnam hospital. The participants were interviewed by a trained researcher. The participants' helmets were collected post-crash. Initially, the helmets were examined for their type and external characteristics. A 3 cm × 3 cm cut was made on the helmet in the impacted and non-impacted areas (control). These areas were investigated for evidence of POD and presence of micro-cracks and material disintegration. 50 participants were enrolled. Sources of information included questionnaire and laboratory analyses. The helmet factors of interest were age of the helmet, exposure of helmet to sunlight and rain (duration/day) and history of previous impact. Laboratory analyses included Fourier Transform Infra Red (FTIR) for degradation and scanning electron microscopy (SEM) for micro-structural examination. Majority of the helmets was the open-face type, 40 (80.0%). 31 (62.0%) helmets aged less than three years (LTY) and 19 (38.0%) were three years old or more (MTY). 19 (61.3%) of the LTY helmets and 12 (63.2%) MTY helmets showed evidence of POD. The duration of helmet exposure to sunlight was between 93 to 6570 hours (mean 2347.74 hours; SD 1733.39). The SEM showed 15 helmets (30%) with micro-fractures, 21 helmets (42.0%) with material disintegration. Prolonged uv exposure to the ABS helmets resulted in changes in the helmet material in the form of material disintegration and microcracks and this association was statistically significant (p = 0.03). POD occurs due to routine exposure to the ultraviolet light. Prolonged uv exposure affects outer shell surface material integrity.

Using exposure prediction tools to link exposure and dosimetry for risk based decisions: a case study with phthalates

EPA Science Inventory

The Population Life-course Exposure to Health Effects Modeling (PLETHEM) platform being developed provides a tool that links results from emerging toxicity testing tools to exposure estimates for humans as defined by the USEPA. A reverse dosimetry case study using phthalates was ...

The Evolution of Silica Nanoparticle-polyester Coatings on Surfaces Exposed to Sunlight.

PubMed

Truong, Vi Khanh; Stefanovic, Miljan; Maclaughlin, Shane; Tobin, Mark; Vongsvivut, Jitraporn; Al Kobaisi, Mohammad; Crawford, Russell J; Ivanova, Elena P

2016-10-11

Corrosion of metallic surfaces is prevalent in the environment and is of great concern in many areas, including the military, transport, aviation, building and food industries, amongst others. Polyester and coatings containing both polyester and silica nanoparticles (SiO2NPs) have been widely used to protect steel substrata from corrosion. In this study, we utilized X-ray photoelectron spectroscopy, attenuated total reflection infrared micro-spectroscopy, water contact angle measurements, optical profiling and atomic force microscopy to provide an insight into how exposure to sunlight can cause changes in the micro- and nanoscale integrity of the coatings. No significant change in surface micro-topography was detected using optical profilometry, however, statistically significant nanoscale changes to the surface were detected using atomic force microscopy. Analysis of the X-ray photoelectron spectroscopy and attenuated total reflection infrared micro-spectroscopy data revealed that degradation of the ester groups had occurred through exposure to ultraviolet light to form COO·, -H2C·, -O·, -CO· radicals. During the degradation process, CO and CO2 were also produced.

The survival of micro-organisms in space. Further rocket and balloon-borne exposure experiments.

PubMed

Hotchin, J; Lorenz, P; Markusen, A; Hemenway, C

1967-01-01

This report describes the results of survival studies of terrestrial micro-organisms exposed directly to the space environment on two balloons and in two rocket flights. The work is part of a program to develop techniques for the collection of micro-organisms in the size range of micrometeorite particles in space or non-terrestrial atmospheres, and their return to earth in a viable state for further study. Previous survival studies were reported (J. Hotchin, P. Lorenz and C. Hemenway, Nature 206 (1965) 442) in which a few relatively large area samples of micro-organisms were exposed on millipore filter cemented to aluminum plates. In the present series of experiments, newly developed techniques have resulted in a 25-fold miniaturization resulting in a corresponding increase in the number of experiments performed. This has enabled a statistical evaluation of the results to be made. A total of 756 separate exposure units (each approximately 5 x 5 mm in size) were flown in four experiments, and organisms used were coliphage T1, penicillium roqueforti (THOM) mold spores, poliovirus type I (Pfizer attenuated Sabin vaccine strain), and bacillus subtilis spores. The organisms were deposited either by spraying directly upon the vinyl-coated metal units, or by droplet seeding into shallow depressions in the millipore filter membrane-coated units. Groups of units were prepared comprising fully exposed, inverted (screened by 2 mm of Al), and filter-protected organisms. All of these were included in the flight set, the back up set, and a laboratory control set. The altitude of the exposures varied from 35 km in the balloon experiments to 150 km in the rocket experiments. Times of exposures at altitude were approximately 6 hours for the balloon flights and about 3 minutes for the rocket experiments.

European solvent industry group generic exposure scenario risk and exposure tool

PubMed Central

Zaleski, Rosemary T; Qian, Hua; Zelenka, Michael P; George-Ares, Anita; Money, Chris

2014-01-01

The European Solvents Industry Group (ESIG) Generic Exposure Scenario (GES) Risk and Exposure Tool (EGRET) was developed to facilitate the safety evaluation of consumer uses of solvents, as required by the European Union Registration, Evaluation and Authorization of Chemicals (REACH) Regulation. This exposure-based risk assessment tool provides estimates of both exposure and risk characterization ratios for consumer uses. It builds upon the consumer portion of the European Center for Ecotoxicology and Toxicology of Chemicals (ECETOC) Targeted Risk Assessment (TRA) tool by implementing refinements described in ECETOC TR107. Technical enhancements included the use of additional data to refine scenario defaults and the ability to include additional parameters in exposure calculations. Scenarios were also added to cover all frequently encountered consumer uses of solvents. The TRA tool structure was modified to automatically determine conditions necessary for safe use. EGRET reports results using specific standard phrases in a format consistent with REACH exposure scenario guidance, in order that the outputs can be readily assimilated within safety data sheets and similar information technology systems. Evaluation of tool predictions for a range of commonly encountered consumer uses of solvents found it provides reasonable yet still conservative exposure estimates. PMID:23361440

European solvent industry group generic exposure scenario risk and exposure tool.

PubMed

Zaleski, Rosemary T; Qian, Hua; Zelenka, Michael P; George-Ares, Anita; Money, Chris

2014-01-01

The European Solvents Industry Group (ESIG) Generic Exposure Scenario (GES) Risk and Exposure Tool (EGRET) was developed to facilitate the safety evaluation of consumer uses of solvents, as required by the European Union Registration, Evaluation and Authorization of Chemicals (REACH) Regulation. This exposure-based risk assessment tool provides estimates of both exposure and risk characterization ratios for consumer uses. It builds upon the consumer portion of the European Center for Ecotoxicology and Toxicology of Chemicals (ECETOC) Targeted Risk Assessment (TRA) tool by implementing refinements described in ECETOC TR107. Technical enhancements included the use of additional data to refine scenario defaults and the ability to include additional parameters in exposure calculations. Scenarios were also added to cover all frequently encountered consumer uses of solvents. The TRA tool structure was modified to automatically determine conditions necessary for safe use. EGRET reports results using specific standard phrases in a format consistent with REACH exposure scenario guidance, in order that the outputs can be readily assimilated within safety data sheets and similar information technology systems. Evaluation of tool predictions for a range of commonly encountered consumer uses of solvents found it provides reasonable yet still conservative exposure estimates.

Between-User Reliability of Tier 1 Exposure Assessment Tools Used Under REACH.

PubMed

Lamb, Judith; Galea, Karen S; Miller, Brian G; Hesse, Susanne; Van Tongeren, Martie

2017-10-01

When applying simple screening (Tier 1) tools to estimate exposure to chemicals in a given exposure situation under the Registration, Evaluation, Authorisation and restriction of CHemicals Regulation 2006 (REACH), users must select from several possible input parameters. Previous studies have suggested that results from exposure assessments using expert judgement and from the use of modelling tools can vary considerably between assessors. This study aimed to investigate the between-user reliability of Tier 1 tools. A remote-completion exercise and in person workshop were used to identify and evaluate tool parameters and factors such as user demographics that may be potentially associated with between-user variability. Participants (N = 146) generated dermal and inhalation exposure estimates (N = 4066) from specified workplace descriptions ('exposure situations') and Tier 1 tool combinations (N = 20). Interactions between users, tools, and situations were investigated and described. Systematic variation associated with individual users was minor compared with random between-user variation. Although variation was observed between choices made for the majority of input parameters, differing choices of Process Category ('PROC') code/activity descriptor and dustiness level impacted most on the resultant exposure estimates. Exposure estimates ranging over several orders of magnitude were generated for the same exposure situation by different tool users. Such unpredictable between-user variation will reduce consistency within REACH processes and could result in under-estimation or overestimation of exposure, risking worker ill-health or the implementation of unnecessary risk controls, respectively. Implementation of additional support and quality control systems for all tool users is needed to reduce between-assessor variation and so ensure both the protection of worker health and avoidance of unnecessary business risk management expenditure. © The Author 2017. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Use of population exposure frequency distributions to simulate effects of policy interventions on NO2 exposure

NASA Astrophysics Data System (ADS)

Dimitroulopoulou, C.; Ashmore, M. R.; Terry, A. C.

2017-02-01

Health effects of air pollution on individuals depend on their personal exposure, but few modelling tools are available which can predict how the distribution of personal exposures within a city will change in response to policies to reduce emissions both indoors and outdoors. We describe a new probabilistic modelling framework (INDAIR-2/EXPAIR), which provides predictions of the personal exposure frequency distribution (PEFD) across a city to assess the effects of both reduced emissions from home sources and reduced roadside concentrations on population exposure. The model uses a national time activity database, which gives the percentage of each population group in different residential and non-residential micro-environments, and links this, for the home, to predictions of concentrations from a three-compartment model, and for non-residential microenvironments to empirical indoor/outdoor ratios. This paper presents modelled PEFDs for NO2 in the city of Leicester, for children, the elderly, and office workers, comparing results in different seasons and on different days of the week. While the mean NO2 population exposure was close to, or below the urban background concentration, the 95%ile of the PEFD was well above the urban background concentration. The relationship between both mean and 95%ile PEFD and urban background concentrations was strongly influenced by air exchange rate. The 24 h mean PEFD showed relative small differences between the population groups, with both removal of home sources and reductions of roadside concentrations on roads with a high traffic density having similar effects in reducing mean exposure. In contrast, the 1 h maximum of the PEFD was significantly higher for children and the elderly than for office workers, and showed a much greater response to reduced home emissions in these groups. The results demonstrate the importance of understanding the dynamics of NO2 exposure at a population level within different groups, if the benefits of policy interventions are to be accurately assessed.

Forming Tool Use Representations: A Neurophysiological Investigation into Tool Exposure

ERIC Educational Resources Information Center

Mizelle, John Christopher; Tang, Teresa; Pirouz, Nikta; Wheaton, Lewis A.

2011-01-01

Prior work has identified a common left parietofrontal network for storage of tool-related information for various tasks. How these representations become established within this network on the basis of different modes of exposure is unclear. Here, healthy subjects engaged in physical practice (direct exposure) with familiar and unfamiliar tools.…

Effects of Process Parameters on Ultrasonic Micro-Hole Drilling in Glass and Ruby

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schorderet, Alain; Deghilage, Emmanuel; Agbeviade, Kossi

2011-05-04

Brittle materials such as ceramics, glasses and oxide single crystals find increasing applications in advanced micro-engineering products. Machining small features in such materials represents a manufacturing challenge. Ultrasonic drilling constitutes a promising technique for realizing simple micro-holes of high diameter-to-depth ratio. The process involves impacting abrasive particles in suspension in a liquid slurry between tool and work piece. Among the process performance criteria, the drilling time (productivity) is one of the most important quantities to evaluate the suitability of the process for industrial applications.This paper summarizes recent results pertaining to the ultrasonic micro-drilling process obtained with a semi-industrial 3-axis machine.more » The workpiece is vibrated at 40 kHz frequency with an amplitude of several micrometers. A voice-coil actuator and a control loop based on the drilling force impose the tool feed. In addition, the tool is rotated at a prescribed speed to improve the drilling speed as well as the hole geometry. Typically, a WC wire serves as tool to bore 200 {mu}m diameter micro-holes of 300 to 1,000 {mu}m depth in glass and ruby. The abrasive slurry contains B4C particles of 1 {mu}m to 5 {mu}m diameter in various concentrations.This paper discusses, on the basis of the experimental results, the influence of several parameters on the drilling time. First, the results show that the control strategy based on the drilling force allows to reach higher feed rates (avoiding tool breakage). Typically, a 8 um/s feed rate is achieved with glass and 0.9 {mu}m/s with ruby. Tool rotation, even for values as low as 50 rpm, increases productivity and improves holes geometry. Drilling with 1 {mu}m and 5 {mu}m B4C particles yields similar productivity results. Our future research will focus on using the presented results to develop a model that can serve to optimize the process for different applications.« less

Radiation dose reduction in the evaluation of scoliosis: an application of digital radiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kushner, D.C.; Cleveland, R.H.; Herman, T.E.

1986-10-01

This report documents the clinical testing of scanning beam digital radiography as an imaging method in patients with scoliosis. This type of digital imaging requires a skin exposure of only 2.4 mR (0.619 microC/kg) per image, compared with the lowest possible posteroanterior screen-film exposure of 10 mR (2.58 microC/kg) at the chest and 60 mR (15.48 microC/kg) at the lumbar spine. Digital radiographic and screen-film images were obtained on multiple test objects and 273 patients. Scoliosis measurements using screen-film radiographs and digital radiographs were comparable to within a mean difference of 1 degrees at many different degrees of severity. Themore » low-dose digital images were found to be useful and accurate for the detection and measurement of scoliosis after the first screen-film radiographs have excluded tumors and structural abnormalities.« less

Intercomparison of radiation measurements on STS-63.

PubMed

Badhwar, G D; Atwell, W; Cash, B; Weyland, M; Petrov, V M; Tchernykh, I V; Akatov YuA; Shurshakov, V A; Arkhangelsky, V V; Kushin, V V; Klyachin, N A; Benton, E V; Frank, A L; Benton, E R; Frigo, L A; Dudkin, V E; Potapov YuV; Vana, N; Schoner, W; Fugger, M

1996-11-01

A joint NASA Russia study of the radiation environment inside the Space Shuttle was performed on STS-63. This was the second flight under the Shuttle-Mir Science Program (Phase 1). The Shuttle was launched on 2 February 1995, in a 51.65 degrees inclination orbit and landed at Kennedy Space Center on 11 February 1995, for a total flight duration of 8.27 days. The Shuttle carried a complement of both passive and active detectors distributed throughout the Shuttle volume. The crew exposure varied from 1962 to 2790 microGy with an average of 2265.8 microGy or 273.98 microGy/day. Crew exposures varied by a factor of 1.4, which is higher than usual for STS mission. The flight altitude varied from 314 to 395 km and provided a unique opportunity to obtain dose variation with altitude. Measurements of the average east-west dose variation were made using two active solid state detectors. The dose rate in the Spacehab locker, measured using a tissue equivalent proportional counter (TEPC), was 413.3 microGy/day, consistent with measurements made using thermoluminescent detectors (TLDs) in the same locker. The average quality factor was 2.33, and although it was higher than model calculations, it was consistent with values derived from high temperature peaks in TLDs. The dose rate due to galactic cosmic radiation was 110.6 microGy/day and agreed with model calculations. The dose rate from trapped particles was 302.7 microGy/day, nearly a factor of 2 lower than the prediction of the AP8 model. The neutrons in the intermediate energy range of 1-20 MeV contributed 13 microGy/day and 156 microSv/day, respectively. Analysis of data from the charged particle spectrometer has not yet been completed.

miTRATA: a web-based tool for microRNA Truncation and Tailing Analysis.

PubMed

Patel, Parth; Ramachandruni, S Deepthi; Kakrana, Atul; Nakano, Mayumi; Meyers, Blake C

2016-02-01

We describe miTRATA, the first web-based tool for microRNA Truncation and Tailing Analysis--the analysis of 3' modifications of microRNAs including the loss or gain of nucleotides relative to the canonical sequence. miTRATA is implemented in Python (version 3) and employs parallel processing modules to enhance its scalability when analyzing multiple small RNA (sRNA) sequencing datasets. It utilizes miRBase, currently version 21, as a source of known microRNAs for analysis. miTRATA notifies user(s) via email to download as well as visualize the results online. miTRATA's strengths lie in (i) its biologist-focused web interface, (ii) improved scalability via parallel processing and (iii) its uniqueness as a webtool to perform microRNA truncation and tailing analysis. miTRATA is developed in Python and PHP. It is available as a web-based application from https://wasabi.dbi.udel.edu/∼apps/ta/. meyers@dbi.udel.edu Supplementary data are available at Bioinformatics online. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Ketamine and thiopental sodium: individual and combined neuroprotective effects on cortical cultures exposed to NMDA or nitric oxide.

PubMed

Shibuta, S; Varathan, S; Mashimo, T

2006-10-01

An N-methyl-D-aspartate (NMDA) blocker, ketamine, has been shown to be neuroprotective both in vivo and in vitro. However, ketamine is not commonly recommended for use in patients suffering from cerebral ischaemia because of its adverse neurological effects. We hypothesized that combined administration of ketamine and thiopental sodium (TPS) would be highly effective in protecting cerebral cortical neurones from ischaemia, with possibly reduced dosages. We examined the degree of neuroprotection provided by various concentrations of ketamine and TPS, alone and in combination, in cortical cultures exposed to NMDA or a nitric oxide-releasing compound (NOC-5) for 24 h. The survival rate (SR) of E16 Wistar rat cortical neurones was evaluated using photomicrographs before and after exposure to these compounds. The SRs of cortical neurones exposed to 30 microM NMDA or NOC-5 were 15.0 (3.8)%, 12.8 (3.1)%, respectively. Higher doses (5, 10 and 50 microM) but not lower doses (<1 microM) of ketamine improved SRs [57.9 (2.2)%, 61.1 (5.4)%, 76.7 (3.0)%, respectively] against NMDA but not NOC. Enhanced survival was observed with combined administration of 5 or 10 microM ketamine and 50 microM TPS [SR 71.3 (4.8)%, 74.7 (3.7)%, respectively, P<0.05 if ketamine alone, P<0.01 if TPS alone], against NMDA-induced neurotoxicity in vitro. Only the highest dose of TPS (50 microM) improved survival after NOC exposure. This neuroprotection was not influenced by ketamine. These data indicate that a low, clinically relevant dose of ketamine offer significant neuroprotection during prolonged exposure to NMDA but not to NOC. Combinations of reduced doses of ketamine and TPS exhibited enhanced neuroprotection against NMDA-induced neurotoxicity. Hence, combinations of these two common i.v. anaesthetics agents could be developed to protect the brain from ischaemia.

MicroRNAs are associated with blood-pressure effects of exposure to particulate matter: Results from a mediated moderation analysis.

PubMed

Motta, Valeria; Favero, Chiara; Dioni, Laura; Iodice, Simona; Battaglia, Cristina; Angelici, Laura; Vigna, Luisella; Pesatori, Angela Cecilia; Bollati, Valentina

2016-04-01

Exposure to particulate air pollution is associated with increased blood pressure (BP), a well-established risk factor for cardiovascular disease. To elucidate the mechanisms underlying this relationship, we investigated whether the effects of particulate matter of less than 10μm in aerodynamic diameter (PM10) on BP are mediated by microRNAs. We recruited 90 obese individuals and we assessed their PM10 exposure 24 and 48h before the recruitment day. We performed multivariate linear regression models to investigate the effects of PM10 on BP. Using the TaqMan® Low-Density Array, we experimentally evaluated and technically validated the expression levels of 377 human miRNAs in peripheral blood. We developed a mediated moderation analysis to estimate the proportion of PM10 effects on BP that was mediated by miRNA expression. PM10 exposure 24 and 48h before the recruitment day was associated with increased systolic BP (β=1.22mmHg, P=0.019; β=1.24mmHg, P=0.019, respectively) and diastolic BP (β=0.67mmHg, P=0.044; β=0.91mmHg, P=0.007, respectively). We identified nine miRNAs associated with PM10 levels 48h after exposure. A conditional indirect effect (CIE=-0.1431) of PM10 on diastolic BP, which was mediated by microRNA-101, was found in individuals with lower values of mean body mass index. Our data provide evidence that miRNAs are a molecular mechanism underlying the BP-related effects of air pollution exposure, and indicate miR-101 as epigenetic mechanism to be further investigated. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Developmental programming: gestational bisphenol-A treatment alters trajectory of fetal ovarian gene expression.

PubMed

Veiga-Lopez, Almudena; Luense, Lacey J; Christenson, Lane K; Padmanabhan, Vasantha

2013-05-01

Bisphenol-A (BPA), a ubiquitous environmental endocrine disrupting chemical, is a component of polycarbonate plastic and epoxy resins. Because of its estrogenic properties, there is increasing concern relative to risks from exposures during critical periods of early organ differentiation. Prenatal BPA treatment in sheep results in low birth weight, hypergonadotropism, and ovarian cycle disruptions. This study tested the hypothesis that gestational exposure to bisphenol A, at an environmentally relevant dose, induces early perturbations in the ovarian transcriptome (mRNA and microRNA). Pregnant Suffolk ewes were treated with bisphenol A (0.5 mg/kg, sc, daily, produced ∼2.6 ng/mL of unconjugated BPA in umbilical arterial samples of BPA treated fetuses approaching median levels of BPA measured in maternal circulation) from days 30 to 90 of gestation. Expression of steroidogenic enzymes, steroid/gonadotropin receptors, key ovarian regulators, and microRNA biogenesis components were measured by RT-PCR using RNA derived from fetal ovaries collected on gestational days 65 and 90. An age-dependent effect was evident in most steroidogenic enzymes, steroid receptors, and key ovarian regulators. Prenatal BPA increased Cyp19 and 5α-reductase expression in day 65, but not day 90, ovaries. Fetal ovarian microRNA expression was altered by prenatal BPA with 45 down-regulated (>1.5-fold) at day 65 and 11 down-regulated at day 90 of gestation. These included microRNAs targeting Sry-related high-mobility-group box (SOX) family genes, kit ligand, and insulin-related genes. The results of this study demonstrate that exposure to BPA at an environmentally relevant dose alters fetal ovarian steroidogenic gene and microRNA expression of relevance to gonadal differentiation, folliculogenesis, and insulin homeostasis.

Microbial phenomics information extractor (MicroPIE): a natural language processing tool for the automated acquisition of prokaryotic phenotypic characters from text sources.

PubMed

Mao, Jin; Moore, Lisa R; Blank, Carrine E; Wu, Elvis Hsin-Hui; Ackerman, Marcia; Ranade, Sonali; Cui, Hong

2016-12-13

The large-scale analysis of phenomic data (i.e., full phenotypic traits of an organism, such as shape, metabolic substrates, and growth conditions) in microbial bioinformatics has been hampered by the lack of tools to rapidly and accurately extract phenotypic data from existing legacy text in the field of microbiology. To quickly obtain knowledge on the distribution and evolution of microbial traits, an information extraction system needed to be developed to extract phenotypic characters from large numbers of taxonomic descriptions so they can be used as input to existing phylogenetic analysis software packages. We report the development and evaluation of Microbial Phenomics Information Extractor (MicroPIE, version 0.1.0). MicroPIE is a natural language processing application that uses a robust supervised classification algorithm (Support Vector Machine) to identify characters from sentences in prokaryotic taxonomic descriptions, followed by a combination of algorithms applying linguistic rules with groups of known terms to extract characters as well as character states. The input to MicroPIE is a set of taxonomic descriptions (clean text). The output is a taxon-by-character matrix-with taxa in the rows and a set of 42 pre-defined characters (e.g., optimum growth temperature) in the columns. The performance of MicroPIE was evaluated against a gold standard matrix and another student-made matrix. Results show that, compared to the gold standard, MicroPIE extracted 21 characters (50%) with a Relaxed F1 score > 0.80 and 16 characters (38%) with Relaxed F1 scores ranging between 0.50 and 0.80. Inclusion of a character prediction component (SVM) improved the overall performance of MicroPIE, notably the precision. Evaluated against the same gold standard, MicroPIE performed significantly better than the undergraduate students. MicroPIE is a promising new tool for the rapid and efficient extraction of phenotypic character information from prokaryotic taxonomic descriptions. However, further development, including incorporation of ontologies, will be necessary to improve the performance of the extraction for some character types.

Procurement of novel microanalysis equipment for construction materials.

DOT National Transportation Integrated Search

2012-02-01

The equipment procured (i.e. an Orbis micro X-ray Fluorescence (MXRF) and an APSEX personal Scanning Electron Microscope (PSEM)) is part of the next generation of micro analytical equipment. These tools have the ability to make large volumes of...

Chronic ethanol consumption modulates growth factor release, mucosal cytokine production, and microRNA expression in nonhuman primates.

PubMed

Asquith, Mark; Pasala, Sumana; Engelmann, Flora; Haberthur, Kristen; Meyer, Christine; Park, Byung; Grant, Kathleen A; Messaoudi, Ilhem

2014-04-01

Chronic alcohol consumption has been associated with enhanced susceptibility to both systemic and mucosal infections. However, the exact mechanisms underlying this enhanced susceptibility remain incompletely understood. Using a nonhuman primate model of ethanol (EtOH) self-administration, we examined the impact of chronic alcohol exposure on immune homeostasis, cytokine, and growth factor production in peripheral blood, lung, and intestinal mucosa following 12 months of chronic EtOH exposure. EtOH exposure inhibited activation-induced production of growth factors hepatocyte growth factor (HGF), granulocyte colony-stimulating factor (G-CSF), and vascular-endothelial growth factor (VEGF) by peripheral blood mononuclear cells (PBMC). Moreover, EtOH significantly reduced the frequency of colonic Th1 and Th17 cells in a dose-dependent manner. In contrast, we did not observe differences in lymphocyte frequency or soluble factor production in the lung of EtOH-consuming animals. To uncover mechanisms underlying reduced growth factor and Th1/Th17 cytokine production, we compared expression levels of microRNAs in PBMC and intestinal mucosa. Our analysis revealed EtOH-dependent up-regulation of distinct microRNAs in affected tissues (miR-181a and miR-221 in PBMC; miR-155 in colon). Moreover, we were able to detect reduced expression of the transcription factors STAT3 and ARNT, which regulate expression of VEGF, G-CSF, and HGF and contain targets for these microRNAs. To confirm and extend these observations, PBMC were transfected with either mimics or antagomirs of miR-181 and miR-221, and protein levels of the transcription factors and growth factors were determined. Transfection of microRNA mimics led to a reduction in both STAT3/ARNT as well as VEGF/HGF/G-CSF levels. The opposite outcome was observed when microRNA antagomirs were transfected. Chronic EtOH consumption significantly disrupts both peripheral and mucosal immune homeostasis, and this dysregulation may be mediated by changes in microRNA expression. Copyright © 2013 by the Research Society on Alcoholism.

Prenatal ethanol exposure alters adult hippocampal VGLUT2 expression with concomitant changes in promoter DNA methylation, H3K4 trimethylation and miR-467b-5p levels.

PubMed

Zhang, Christine R; Ho, Mei-Fong; Vega, Michelle C Sanchez; Burne, Thomas H J; Chong, Suyinn

2015-01-01

Maternal consumption of alcohol during pregnancy is associated with a range of physical, cognitive and behavioural outcomes in the offspring which are collectively called foetal alcohol spectrum disorders. We and others have proposed that epigenetic modifications, such as DNA methylation and post-translational histone modifications, mediate the effects of prenatal alcohol exposure on gene expression and, ultimately, phenotype. Here we use an inbred C57BL/6J mouse model of early gestational ethanol exposure equivalent, developmentally, to the first 3-4 weeks of pregnancy in humans to examine the long-term effects on gene expression and epigenetic state in the hippocampus. Gene expression analysis in the hippocampus revealed sex- and age-specific up-regulation of solute carrier family 17 member 6 (Slc17a6), which encodes vesicular glutamate transporter 2 (VGLUT2). Transcriptional up-regulation correlated with decreased DNA methylation and enrichment of histone H3 lysine 4 trimethylation, an active chromatin mark, at the Slc17a6 promoter. In contrast to Slc17a6 mRNA levels, hippocampal VGLUT2 protein levels were significantly decreased in adult ethanol-exposed offspring, suggesting an additional level of post-transcriptional control. MicroRNA expression profiling in the hippocampus identified four ethanol-sensitive microRNAs, of which miR-467b-5p was predicted to target Slc17a6. In vitro reporter assays showed that miR-467b-5p specifically interacted with the 3'UTR of Slc17a6, suggesting that it contributes to the reduction of hippocampal VGLUT2 in vivo. A significant correlation between microRNA expression in the hippocampus and serum of ethanol-exposed offspring was also observed. Prenatal ethanol exposure has complex transcriptional and post-transcriptional effects on Slc17a6 (VGLUT2) expression in the mouse hippocampus. These effects are observed following a relatively moderate exposure that is restricted to early pregnancy, modelling human consumption of alcohol before pregnancy is confirmed, and are only apparent in male offspring in adulthood. Our findings are consistent with the idea that altered epigenetic and/or microRNA-mediated regulation of glutamate neurotransmission in the hippocampus contributes to the cognitive and behavioural phenotypes observed in foetal alcohol spectrum disorders. Although further work is needed in both mice and humans, the results also suggest that circulating microRNAs could be used as biomarkers of early gestational ethanol exposure and hippocampal dysfunction.

TLD assessment of mouse dosimetry during microCT imaging

PubMed Central

Figueroa, Said Daibes; Winkelmann, Christopher T.; Miller, William H.; Volkert, Wynn A.; Hoffman, Timothy J.

2008-01-01

Advances in laboratory animal imaging have provided new resources for noninvasive biomedical research. Among these technologies is microcomputed tomography (microCT) which is widely used to obtain high resolution anatomic images of small animals. Because microCT utilizes ionizing radiation for image formation, radiation exposure during imaging is a concern. The objective of this study was to quantify the radiation dose delivered during a standard microCT scan. Radiation dose was measured using thermoluminescent dosimeters (TLDs), which were irradiated employing an 80 kVp x-ray source, with 0.5 mm Al filtration and a total of 54 mA s for a full 360 deg rotation of the unit. The TLD data were validated using a 3.2 cm3 CT ion chamber probe. TLD results showed a single microCT scan air kerma of 78.0±5.0 mGy when using a poly(methylmethacrylate) (PMMA) anesthesia support module and an air kerma of 92.0±6.0 mGy without the use of the anesthesia module. The validation CT ion chamber study provided a measured radiation air kerma of 81.0±4.0 mGy and 97.0±5.0 mGy with and without the PMMA anesthesia module, respectively. Internal TLD analysis demonstrated an average mouse organ radiation absorbed dose of 76.0±5.0 mGy. The author’s results have defined x-ray exposure for a routine microCT study which must be taken into consideration when performing serial molecular imaging studies involving the microCT imaging modality. PMID:18841837

EPA EcoBox Tools by Exposure Pathways - Exposure Pathways In ERA

EPA Pesticide Factsheets

Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Computational Systems Biology Approach Predicts Regulators and Targets of microRNAs and Their Genomic Hotspots in Apoptosis Process.

PubMed

Alanazi, Ibrahim O; Ebrahimie, Esmaeil

2016-07-01

Novel computational systems biology tools such as common targets analysis, common regulators analysis, pathway discovery, and transcriptomic-based hotspot discovery provide new opportunities in understanding of apoptosis molecular mechanisms. In this study, after measuring the global contribution of microRNAs in the course of apoptosis by Affymetrix platform, systems biology tools were utilized to obtain a comprehensive view on the role of microRNAs in apoptosis process. Network analysis and pathway discovery highlighted the crosstalk between transcription factors and microRNAs in apoptosis. Within the transcription factors, PRDM1 showed the highest upregulation during the course of apoptosis, with more than 9-fold expression increase compared to non-apoptotic condition. Within the microRNAs, MIR1208 showed the highest expression in non-apoptotic condition and downregulated by more than 6 fold during apoptosis. Common regulators algorithm showed that TNF receptor is the key upstream regulator with a high number of regulatory interactions with the differentially expressed microRNAs. BCL2 and AKT1 were the key downstream targets of differentially expressed microRNAs. Enrichment analysis of the genomic locations of differentially expressed microRNAs led us to the discovery of chromosome bands which were highly enriched (p < 0.01) with the apoptosis-related microRNAs, such as 13q31.3, 19p13.13, and Xq27.3 This study opens a new avenue in understanding regulatory mechanisms and downstream functions in the course of apoptosis as well as distinguishing genomic-enriched hotspots for apoptosis process.

Free-floating epithelial micro-tissue arrays: a low cost and versatile technique.

PubMed

Flood, P; Alvarez, L; Reynaud, E G

2016-10-11

Three-dimensional (3D) tissue models are invaluable tools that can closely reflect the in vivo physiological environment. However, they are usually difficult to develop, have a low throughput and are often costly; limiting their utility to most laboratories. The recent availability of inexpensive additive manufacturing printers and open source 3D design software offers us the possibility to easily create affordable 3D cell culture platforms. To demonstrate this, we established a simple, inexpensive and robust method for producing arrays of free-floating epithelial micro-tissues. Using a combination of 3D computer aided design and 3D printing, hydrogel micro-moulding and collagen cell encapsulation we engineered microenvironments that consistently direct the growth of micro-tissue arrays. We described the adaptability of this technique by testing several immortalised epithelial cell lines (MDCK, A549, Caco-2) and by generating branching morphology and micron to millimetre scaled micro-tissues. We established by fluorescence and electron microscopy that micro-tissues are polarised, have cell type specific differentiated phenotypes and regain native in vivo tissue qualities. Finally, using Salmonella typhimurium we show micro-tissues display a more physiologically relevant infection response compared to epithelial monolayers grown on permeable filter supports. In summary, we have developed a robust and adaptable technique for producing arrays of epithelial micro-tissues. This in vitro model has the potential to be a valuable tool for studying epithelial cell and tissue function/architecture in a physiologically relevant context.

Usewear studies of flint tools with microPIXE and microRBS

NASA Astrophysics Data System (ADS)

Christensen, Marianne; Grime, Geoff; Menu, Michel; Walter, Philippe

1993-05-01

The use of ancient stone tools leaves a polish (usewear) on the cutting edge which can be studied to determine the material the tool had worked during its use. The film is formed by high pressure intrusion of the worked material into the microcavities of the chipped flint surface and so the film can also be analysed directly to determine the nature of the worked material. This paper describes the analysis of experimental flint tools which had worked bone and ivory using microbeam PIXE and RBS. It is found that PIXE used simultaneously with RBS allows the thickness and composition of the film to be determined and ivory distinguished from bone while RBS mapping allows the three-dimensional structure of the film to be determined.

Status of ion sources at National Institute of Radiological Sciences.

PubMed

Kitagawa, A; Fujita, T; Goto, A; Hattori, T; Hamano, T; Hojo, S; Honma, T; Imaseki, H; Katagiri, K; Muramatsu, M; Sakamoto, Y; Sekiguchi, M; Suda, M; Sugiura, A; Suya, N

2012-02-01

The National Institute of Radiological Sciences (NIRS) maintains various ion accelerators in order to study the effects of radiation of the human body and medical uses of radiation. Two electrostatic tandem accelerators and three cyclotrons delivered by commercial companies have offered various life science tools; these include proton-induced x-ray emission analysis (PIXE), micro beam irradiation, neutron exposure, and radioisotope tracers and probes. A duoplasmatron, a multicusp ion source, a penning ion source (PIG), and an electron cyclotron resonance ion source (ECRIS) are in operation for these purposes. The Heavy-Ion Medical Accelerator in Chiba (HIMAC) is an accelerator complex for heavy-ion radiotherapy, fully developed by NIRS. HIMAC is utilized not only for daily treatment with the carbon beam but also for fundamental experiments. Several ECRISs and a PIG at HIMAC satisfy various research and clinical requirements.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kitagawa, A.; Fujita, T.; Goto, A.

The National Institute of Radiological Sciences (NIRS) maintains various ion accelerators in order to study the effects of radiation of the human body and medical uses of radiation. Two electrostatic tandem accelerators and three cyclotrons delivered by commercial companies have offered various life science tools; these include proton-induced x-ray emission analysis (PIXE), micro beam irradiation, neutron exposure, and radioisotope tracers and probes. A duoplasmatron, a multicusp ion source, a penning ion source (PIG), and an electron cyclotron resonance ion source (ECRIS) are in operation for these purposes. The Heavy-Ion Medical Accelerator in Chiba (HIMAC) is an accelerator complex for heavy-ionmore » radiotherapy, fully developed by NIRS. HIMAC is utilized not only for daily treatment with the carbon beam but also for fundamental experiments. Several ECRISs and a PIG at HIMAC satisfy various research and clinical requirements.« less

Status of ion sources at National Institute of Radiological Sciencesa)

NASA Astrophysics Data System (ADS)

Kitagawa, A.; Fujita, T.; Goto, A.; Hattori, T.; Hamano, T.; Hojo, S.; Honma, T.; Imaseki, H.; Katagiri, K.; Muramatsu, M.; Sakamoto, Y.; Sekiguchi, M.; Suda, M.; Sugiura, A.; Suya, N.

2012-02-01

The National Institute of Radiological Sciences (NIRS) maintains various ion accelerators in order to study the effects of radiation of the human body and medical uses of radiation. Two electrostatic tandem accelerators and three cyclotrons delivered by commercial companies have offered various life science tools; these include proton-induced x-ray emission analysis (PIXE), micro beam irradiation, neutron exposure, and radioisotope tracers and probes. A duoplasmatron, a multicusp ion source, a penning ion source (PIG), and an electron cyclotron resonance ion source (ECRIS) are in operation for these purposes. The Heavy-Ion Medical Accelerator in Chiba (HIMAC) is an accelerator complex for heavy-ion radiotherapy, fully developed by NIRS. HIMAC is utilized not only for daily treatment with the carbon beam but also for fundamental experiments. Several ECRISs and a PIG at HIMAC satisfy various research and clinical requirements.

Rapid microRNA changes in airways of human volunteers after controlled exposure to air pollutants

EPA Science Inventory

Introduction/Rationale: Exposure to air pollutants, including ozone and diesel exhaust (DE) are known to cause acute cardiopulmonary dysfunction; however, the molecular mechanisms underlying these changes remain elusive. One mechanism for rapid regulation of multiple genes is a...

Radiation stability of SiO2 micro- and nanopowders under electron and proton exposure

NASA Astrophysics Data System (ADS)

Li, Chundong; Mikhailov, M. M.; Neshchimenko, V. V.

2014-01-01

The effects of proton and electron (E = 100 keV, F = 5 × 1015 сm-2) exposure on the reflective spectra of SiO2 micro- and nanopowders in wavelength range from 250 to 2500 nm have been investigated. It has been established that the reflectance and radiation stability of nanopowders is less than that of micropowders. This effect is caused by the high concentration of radiation defects, which act as surface absorption centers (Es‧ centers) near the energies 5.47 and 4.45 eV, and peroxide silicon defects (tbnd Sisbnd Osbnd Osbnd Sitbnd) near the energy 3.84 eV.

Micro-ultrasound for preclinical imaging

PubMed Central

Foster, F. Stuart; Hossack, John; Adamson, S. Lee

2011-01-01

Over the past decade, non-invasive preclinical imaging has emerged as an important tool to facilitate biomedical discovery. Not only have the markets for these tools accelerated, but the numbers of peer-reviewed papers in which imaging end points and biomarkers have been used have grown dramatically. High frequency ‘micro-ultrasound’ has steadily evolved in the post-genomic era as a rapid, comparatively inexpensive imaging tool for studying normal development and models of human disease in small animals. One of the fundamental barriers to this development was the technological hurdle associated with high-frequency array transducers. Recently, new approaches have enabled the upper limits of linear and phased arrays to be pushed from about 20 to over 50 MHz enabling a broad range of new applications. The innovations leading to the new transducer technology and scanner architecture are reviewed. Applications of preclinical micro-ultrasound are explored for developmental biology, cancer, and cardiovascular disease. With respect to the future, the latest developments in high-frequency ultrasound imaging are described. PMID:22866232

Study on residual stresses in ultrasonic torsional vibration assisted micro-milling

NASA Astrophysics Data System (ADS)

Lu, Zesheng; Hu, Haijun; Sun, Yazhou; Sun, Qing

2010-10-01

It is well known that machining induced residual stresses can seriously affect the dimensional accuracy, corrosion and wear resistance, etc., and further influence the longevity and reliability of Micro-Optical Components (MOC). In Ultrasonic Torsional Vibration Assisted Micro-milling (UTVAM), cutting parameters, vibration parameters, mill cutter parameters, the status of wear length of tool flank are the main factors which affect residual stresses. A 2D model of UTVAM was established with FE analysis software ABAQUS. Johnson-Cook's flow stress model and shear failure principle are used as the workpiece material model and failure principle, while friction between tool and workpiece uses modified Coulomb's law whose sliding friction area is combined with sticking friction. By means of FEA, the influence rules of cutting parameters, vibration parameters, mill cutter parameters, the status of wear length of tool flank on residual stresses are obtained, which provides a basis for choosing optimal process parameters and improving the longevity and reliability of MOC.

Exposure Assessment Tools by Approaches - Exposure Reconstruction (Biomonitoring and Reverse Dosimetry)

EPA Pesticide Factsheets

This page provides access to a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases,

Differential expression of miRNA-423-5p in serum from cattle challenged with bovine viral diarrhea virus

USDA-ARS?s Scientific Manuscript database

Bovine viral diarrhea virus (BVDV) is an RNA virus that causes respiratory disease in cattle. MicroRNAs have been proposed as indicators of exposure to respiratory pathogens. However, microRNA profiles in cattle exposed to BVDV are currently nonexistent and few studies have been reported; therefore,...

Compact self-aligning assemblies with refractive microlens arrays made by contactless embossing

NASA Astrophysics Data System (ADS)

Schulze, Jens; Ehrfeld, Wolfgang; Mueller, Holger; Picard, Antoni

1998-04-01

The hybrid integration of microlenses and arrays of microlenses in micro-optical systems is simplified using contactless embossing of microlenses (CEM) in combination with LIGA microfabrication. CEM is anew fabrication technique for the production of precise refractive microlens arrays. A high precision matrix of holes made by LIGA technique is used as a compression molding tool to form the microlenses. The tool is pressed onto a thermoplastic sample which is heated close to the glass transformation temperature of the material. The material bulges into the openings of the molding tool due to the applied pressure and forms lens-like spherical structures. The name refers to the fact that the surface of the microlens does not get in contact with the compression molding tool during the shaping process and optical quality of the surface is maintained. Microlenses and arrays of microlenses with lens diameters from 30 micrometers up to 700 micrometers and numerical aperture values of up to 0.25 have been fabricated in different materials. Cost-effectiveness in the production process, excellent optical performance and the feature of easy replication are the main advantages of this technique. The most promising feature of this method is the possibility to obtain self- aligned assemblies then can be further integrated into a micro-optical bench setup. The CEM fabrication method in combination with LIGA microfabrication considerably enhances the hybrid integration in micro-optical devices which results in a more cost-effective production of compact micro-opto-electro-mechanical systems.

CO 2-induced chemo-mechanical alteration in reservoir rocks assessed via batch reaction experiments and scratch testing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aman, Michael; Espinoza, D. Nicolas; Ilgen, Anastasia G.

Here, the injection of carbon dioxide (CO 2) into geological formations results in a chemical re-equilibration between the mineral assemblage and the pore fluid, with ensuing mineral dissolution and re-precipitation. Hence, target rock formations may exhibit changes of mechanical and petrophysical properties due to CO 2 exposure. We conducted batch reaction experiments with Entrada Sandstone and Summerville Siltstone exposed to de-ionized water and synthetic brine under reservoir pressure (9–10 MPa) and temperature (80°C) for up to four weeks. Samples originate from the Crystal Geyser field site, where a naturally occurring CO 2 seepage alters portions of these geologic formations. Wemore » conducted micro-scratch tests on rock samples without alteration, altered under laboratory conditions, and naturally altered over geologic time. Scratch toughness and hardness decrease as a function of exposure time and water salinity up to 52% in the case of Entrada and 87% in the case of Summerville after CO 2-induced alteration in the laboratory. Imaging of altered cores with SEM-EDS and X-ray microCT methods show dissolution of carbonate and silica cements and matrix accompanied by minor dissolution of Fe-oxides, clays, and other silicates. Parallel experiments using powdered samples confirm that dissolution of carbonate and silica are the primary reactions. The batch reaction experiments in the autoclave utilize a high fluid to rock volume ratio and represent an end member of possible alteration associated with CO 2 storage systems. These types of tests serve as a pre-screening tool to identify the susceptibility of rock facies to CO 2-related chemical-mechanical alteration during long-term CO 2 storage.« less

CO 2-induced chemo-mechanical alteration in reservoir rocks assessed via batch reaction experiments and scratch testing

DOE PAGES

Aman, Michael; Espinoza, D. Nicolas; Ilgen, Anastasia G.; ...

2017-09-22

Here, the injection of carbon dioxide (CO 2) into geological formations results in a chemical re-equilibration between the mineral assemblage and the pore fluid, with ensuing mineral dissolution and re-precipitation. Hence, target rock formations may exhibit changes of mechanical and petrophysical properties due to CO 2 exposure. We conducted batch reaction experiments with Entrada Sandstone and Summerville Siltstone exposed to de-ionized water and synthetic brine under reservoir pressure (9–10 MPa) and temperature (80°C) for up to four weeks. Samples originate from the Crystal Geyser field site, where a naturally occurring CO 2 seepage alters portions of these geologic formations. Wemore » conducted micro-scratch tests on rock samples without alteration, altered under laboratory conditions, and naturally altered over geologic time. Scratch toughness and hardness decrease as a function of exposure time and water salinity up to 52% in the case of Entrada and 87% in the case of Summerville after CO 2-induced alteration in the laboratory. Imaging of altered cores with SEM-EDS and X-ray microCT methods show dissolution of carbonate and silica cements and matrix accompanied by minor dissolution of Fe-oxides, clays, and other silicates. Parallel experiments using powdered samples confirm that dissolution of carbonate and silica are the primary reactions. The batch reaction experiments in the autoclave utilize a high fluid to rock volume ratio and represent an end member of possible alteration associated with CO 2 storage systems. These types of tests serve as a pre-screening tool to identify the susceptibility of rock facies to CO 2-related chemical-mechanical alteration during long-term CO 2 storage.« less

Different relationships between personal exposure and ambient concentration by particle size.

PubMed

Guak, Sooyoung; Lee, Kiyoung

2018-04-06

Ambient particulate matter (PM) concentrations at monitoring stations were often used as an indicator of population exposure to PM in epidemiological studies. The correlation between personal exposure and ambient concentrations of PM varied because of diverse time-activity patterns. The aim of this study was to determine the relationship between personal exposure and ambient concentrations of PM 10 and PM 2.5 with minimal impact of time-activity pattern on personal exposure. Performance of the MicroPEM, v3.2 was evaluated by collocation with central ambient air monitors for PM 10 and PM 2.5 . A field technician repeatedly conducted measurement of 24 h personal exposures to PM 10 and PM 2.5 with a fixed time-activity pattern of office worker over 26 days in Seoul, Korea. The relationship between the MicroPEM and the ambient air monitor showed good linearity. Personal exposure and ambient concentrations of PM 2.5 were highly correlated with a fixed time-activity pattern compared with PM 10 . The finding implied a high infiltration rate of PM 2.5 and low infiltration rate of PM 10 . The relationship between personal exposure and ambient concentrations of PM 10 and PM 2.5 was different for high level episodes. In the Asian dust episode, staying indoors could reduce personal exposure to PM 10 . However, personal exposure to PM 2.5 could not be reduced by staying indoors during the fine dust advisory episode.

Cost of behavior change communication channels of Manoshi -a maternal, neonatal and child health (MNCH) program in urban slums of Dhaka, Bangladesh

PubMed Central

2013-01-01

Background The cost of behavior change communication (BCC) interventions has not been rigorously studied in Bangladesh. This study was conducted to assess the implementation costs of a BCC intervention in a maternal, neonatal and child health program (Manoshi) run by BRAC, which has been operating in the urban slums of Dhaka since 2007. The study estimates the costs of BCC tools per exposure among the different types of BCC channels: face-to-face, group counseling, and mass media. Methods The study was conducted from November 2010 to April 2011 in the Dhaka urban slum area. A micro-costing approach was applied using primary and secondary data sources to estimate the cost of BCC tools. Primary data were collected through interviews with service-providers and managers from the Manoshi program, observations of group counseling, and mass media events. Results Per exposure, the cost of face-to-face counseling was found to be 3.08 BDT during pregnancy detection, 3.11 BDT during pregnancy confirmation, 12.42 BDT during antenatal care, 18.96 BDT during delivery care and 22.65 BDT during post-natal care. The cost per exposure of group counseling was 22.71 BDT (95% CI 21.30-24.87) for Expected Date of Delivery (EDD) meetings, 14.25 BDT (95% CI 12.37-16.12) for Women Support Group meetings, 17.83 BDT (95% CI 14.90-20.77) for MNCH committee meetings and 6.62 BDT (95% CI 5.99-7.26) for spouse forum meetings. We found the cost per exposure for mass media interventions was 9.54 BDT (95% CI 7.30-12.53) for folk songs, 26.39 BDT (95% CI 23.26-32.56) for street dramas, 0.39 BDT for TV-broadcasting and 7.87 BDT for billboards. Considering all components reaching the target audience under each broader type of channel, the total cost per exposure was found to be 60.22 BDT (0.82 USD) for face-to-face counseling, 61.40 BDT (0.82 USD) for group counseling and 44.19 BDT (0.61 USD) for mass media. Conclusions The total cost for group counseling was the highest per exposure, followed by face-to-face counseling and mass media. The cost per exposure varied substantially across BCC channels due to differences in cost drivers such as personnel, materials and refreshments. The cost per exposure can be valuable for planning and resource allocation related to the implementation of BCC interventions in low resource settings. PMID:24228844

Low-parachor solvents extraction and thermostated micro-thin-layer chromatography separation for fast screening and classification of spirulina from pharmaceutical formulations and food samples.

PubMed

Zarzycki, Paweł K; Zarzycka, Magdalena B; Clifton, Vicki L; Adamski, Jerzy; Głód, Bronisław K

2011-08-19

The goal of this paper is to demonstrate the separation and detection capability of eco-friendly micro-TLC technique for the classification of spirulina and selected herbs from pharmaceutical and food products. Target compounds were extracted using relatively low-parachor liquids. A number of the spirulina samples which originated from pharmaceutical formulations and food products, were isolated using a simple one step extraction with small volume of methanol, acetone or tetrahydrofuran. Herb samples rich in chlorophyll dyes were analyzed as reference materials. Quantitative data derived from micro-plates under visible light conditions and after iodine staining were explored using chemometrics tools including cluster analysis and principal components analysis. Using this method we could easily distinguish genuine spirulina and non-spirulina samples as well as fresh from expired commercial products and furthermore, we could identify some biodegradation peaks appearing on micro-TLC profiles. This methodology can be applied as a fast screening or fingerprinting tool for the classification of genuine spirulina and herb samples and in particular may be used commercially for the rapid quality control screening of products. Furthermore, this approach allows low-cost fractionation of target substances including cyanobacteria pigments in raw biological or environmental samples for preliminary chemotaxonomic investigations. Due to the low consumption of the mobile phase (usually less than 1 mL per run), this method can be considered as environmentally friendly analytical tool, which may be an alternative for fingerprinting protocols based on HPLC machines and simple separation systems involving planar micro-fluidic or micro-chip devices. Copyright © 2011 Elsevier B.V. All rights reserved.

Serum microRNA biomarker identification in a residential cohort with elevated polychlorinated biphenyl exposures.

EPA Science Inventory

Toxicant-associated steatohepatitis (TASH) is a form of liver disease associated with both industrial [1] and environmental [2] chemical exposures. Like other forms of Non-alcoholic Fatty Liver Disease (NAFLD), TASH can contribute to systemic metabolic disease states and may prog...

Micro Computer Tomography for medical device and pharmaceutical packaging analysis.

PubMed

Hindelang, Florine; Zurbach, Raphael; Roggo, Yves

2015-04-10

Biomedical device and medicine product manufacturing are long processes facing global competition. As technology evolves with time, the level of quality, safety and reliability increases simultaneously. Micro Computer Tomography (Micro CT) is a tool allowing a deep investigation of products: it can contribute to quality improvement. This article presents the numerous applications of Micro CT for medical device and pharmaceutical packaging analysis. The samples investigated confirmed CT suitability for verification of integrity, measurements and defect detections in a non-destructive manner. Copyright © 2015 Elsevier B.V. All rights reserved.

Exposure Assessment Tools by Media - Air

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Exposure Assessment Tools by Routes - Inhalation

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Exposure Assessment Tools by Chemical Classes

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Exposure Assessment Tools by Routes

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Exposure Assessment Tools by Media - Food

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Exposure Assessment Tools by Media

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Exposure Assessment Tools by Routes - Ingestion

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Exposure Assessment Tools by Approaches

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Exposure Assessment Tools by Routes - Dermal

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

EPA EcoBox Tools by Exposure Pathways

EPA Pesticide Factsheets

Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Improving exposure assessment in environmental epidemiology: Application of spatio-temporal visualization tools

NASA Astrophysics Data System (ADS)

Meliker, Jaymie R.; Slotnick, Melissa J.; Avruskin, Gillian A.; Kaufmann, Andrew; Jacquez, Geoffrey M.; Nriagu, Jerome O.

2005-05-01

A thorough assessment of human exposure to environmental agents should incorporate mobility patterns and temporal changes in human behaviors and concentrations of contaminants; yet the temporal dimension is often under-emphasized in exposure assessment endeavors, due in part to insufficient tools for visualizing and examining temporal datasets. Spatio-temporal visualization tools are valuable for integrating a temporal component, thus allowing for examination of continuous exposure histories in environmental epidemiologic investigations. An application of these tools to a bladder cancer case-control study in Michigan illustrates continuous exposure life-lines and maps that display smooth, continuous changes over time. Preliminary results suggest increased risk of bladder cancer from combined exposure to arsenic in drinking water (>25 μg/day) and heavy smoking (>30 cigarettes/day) in the 1970s and 1980s, and a possible cancer cluster around automotive, paint, and organic chemical industries in the early 1970s. These tools have broad application for examining spatially- and temporally-specific relationships between exposures to environmental risk factors and disease.

High Power Picosecond Laser Surface Micro-texturing of H13 Tool Steel and Pattern Replication onto ABS Plastics via Injection Moulding

NASA Astrophysics Data System (ADS)

Otanocha, Omonigho B.; Li, Lin; Zhong, Shan; Liu, Zhu

2016-03-01

H13 tool steels are often used as dies and moulds for injection moulding of plastic components. Certain injection moulded components require micro-patterns on their surfaces in order to modify the physical properties of the components or for better mould release to reduce mould contamination. With these applications it is necessary to study micro-patterning to moulds and to ensure effective pattern transfer and replication onto the plastic component during moulding. In this paper, we report an investigation into high average powered (100 W) picosecond laser interactions with H13 tool steel during surface micro-patterning (texturing) and the subsequent pattern replication on ABS plastic material through injection moulding. Design of experiments and statistical modelling were used to understand the influences of laser pulse repetition rate, laser fluence, scanning velocity, and number of scans on the depth of cut, kerf width and heat affected zones (HAZ) size. The characteristics of the surface patterns are analysed. The process parameter interactions and significance of process parameters on the processing quality and efficiency are characterised. An optimum operating window is recommended. The transferred geometry is compared with the patterns generated on the dies. A discussion is made to explain the characteristics of laser texturing and pattern replication on plastics.

Imaging techniques for visualizing and phenotyping congenital heart defects in murine models.

PubMed

Liu, Xiaoqin; Tobita, Kimimasa; Francis, Richard J B; Lo, Cecilia W

2013-06-01

Mouse model is ideal for investigating the genetic and developmental etiology of congenital heart disease. However, cardiovascular phenotyping for the precise diagnosis of structural heart defects in mice remain challenging. With rapid advances in imaging techniques, there are now high throughput phenotyping tools available for the diagnosis of structural heart defects. In this review, we discuss the efficacy of four different imaging modalities for congenital heart disease diagnosis in fetal/neonatal mice, including noninvasive fetal echocardiography, micro-computed tomography (micro-CT), micro-magnetic resonance imaging (micro-MRI), and episcopic fluorescence image capture (EFIC) histopathology. The experience we have gained in the use of these imaging modalities in a large-scale mouse mutagenesis screen have validated their efficacy for congenital heart defect diagnosis in the tiny hearts of fetal and newborn mice. These cutting edge phenotyping tools will be invaluable for furthering our understanding of the developmental etiology of congenital heart disease. Copyright © 2013 Wiley Periodicals, Inc.

Exposure assessment in health assessments for hand-arm vibration syndrome.

PubMed

Mason, H J; Poole, K; Young, C

2011-08-01

Assessing past cumulative vibration exposure is part of assessing the risk of hand-arm vibration syndrome (HAVS) in workers exposed to hand-arm vibration and invariably forms part of a medical assessment of such workers. To investigate the strength of relationships between the presence and severity of HAVS and different cumulative exposure metrics obtained from a self-reporting questionnaire. Cumulative exposure metrics were constructed from a tool-based questionnaire applied in a group of HAVS referrals and workplace field studies. These metrics included simple years of vibration exposure, cumulative total hours of all tool use and differing combinations of acceleration magnitudes for specific tools and their daily use, including the current frequency-weighting method contained in ISO 5349-1:2001. Use of simple years of exposure is a weak predictor of HAVS or its increasing severity. The calculation of cumulative hours across all vibrating tools used is a more powerful predictor. More complex calculations based on involving likely acceleration data for specific classes of tools, either frequency weighted or not, did not offer a clear further advantage in this dataset. This may be due to the uncertainty associated with workers' recall of their past tool usage or the variability between tools in the magnitude of their vibration emission. Assessing years of exposure or 'latency' in a worker should be replaced by cumulative hours of tool use. This can be readily obtained using a tool-pictogram-based self-reporting questionnaire and a simple spreadsheet calculation.

Early changes in coronary artery wall structure detected by microcomputed tomography in experimental hypercholesterolemia.

PubMed

Zhu, Xiang-Yang; Bentley, Michael D; Chade, Alejandro R; Ritman, Erik L; Lerman, Amir; Lerman, Lilach O

2007-09-01

Changes in the structure of the artery wall commence shortly after exposure to cardiovascular risk factors, such as hypercholesterolemia (HC), but may be difficult to detect. The ability to study vascular wall structure could be helpful in evaluation of the factors that instigate atherosclerosis and its pathomechanisms. The present study tested the hypothesis that early morphological changes in coronary arteries of hypercholesterolemic (HC) pigs can be detected using the novel X-ray contrast agent OsO(4) and three-dimensional micro-computed tomography (CT). Two groups of pigs were studied after they were fed a normal or an HC (2% cholesterol) diet for 12 wk. Hearts were harvested, coronary arteries were injected with 1% OsO(4) solution, and cardiac samples (6-mum-thick) were scanned by micro-CT. Layers of the epicardial coronary artery wall, early lesions, and perivascular OsO(4) accumulation were determined. Leakage of OsO(4) from myocardial microvessels was used to assess vascular permeability, which was correlated with immunoreactivity of vascular endothelial growth factor in corresponding histological cross sections. OsO(4) enhanced the visualization of coronary artery wall layers and facilitated detection of early lesions in HC in longitudinal tomographic sections of vascular segments. Increased density of perivascular OsO(4) in HC was correlated with increased vascular endothelial growth factor expression and suggested increased microvascular permeability. The use of OsO(4) as a contrast agent in micro-CT allows three-dimensional visualization of coronary artery wall structure, early lesion formation, and changes in vascular permeability. Therefore, this technique can be a useful tool in atherosclerosis research.

Exposure Assessment Tools by Chemical Classes - Nanomaterials

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Exposure Assessment Tools by Chemical Classes - Other Organics

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Exposure Assessment Tools by Lifestages and Populations - Lifestages

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Exposure Assessment Tools by Lifestages and Populations

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Exposure Assessment Tools by Media - Consumer Products

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Exposure Assessment Tools by Media - Water and Sediment

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Exposure Assessment Tools by Tiers and Types

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Exposure Assessment Tools by Media - Soil and Dust

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Exposure Assessment Tools by Chemical Classes - Pesticides

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Exposure Assessment Tools by Media - Aquatic Biota

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Exposure Assessment Tools by Media - Soil and Dust

EPA Pesticide Factsheets

2017-02-13

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Exposure Assessment Tools by Chemical Classes - Other ...

EPA Pesticide Factsheets

2017-02-13

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

EPA EcoBox Tools by Exposure Pathways - Soil

EPA Pesticide Factsheets

Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

EPA EcoBox Tools by Exposure Pathways - Food Chains

EPA Pesticide Factsheets

Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

EPA EcoBox Tools by Exposure Pathways - References

EPA Pesticide Factsheets

Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

EPA EcoBox Tools by Exposure Pathways - Air

EPA Pesticide Factsheets

Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

MicroRNAs as targets for dietary and pharmacological inhibitors of mutagenesis and carcinogenesis

PubMed Central

Izzotti, Alberto; Cartiglia, Cristina; Steele, Vernon E.; De Flora, Silvio

2012-01-01

MicroRNAs (miRNAs) have been implicated in many biological processes, cancer, and other diseases. In addition, miRNAs are dysregulated following exposure to toxic and genotoxic agents. Here we review studies evaluating modulation of miRNAs by dietary and pharmacological agents, which could potentially be exploited for inhibition of mutagenesis and carcinogenesis. This review covers natural agents, including vitamins, oligoelements, polyphenols, isoflavones, indoles, isothiocyanates, phospholipids, saponins, anthraquinones and polyunsaturated fatty acids, and synthetic agents, including thiols, nuclear receptor agonists, histone deacetylase inhibitors, antiinflammatory drugs, and selective estrogen receptor modulators. As many as 145 miRNAs, involved in the control of a variety of carcinogenesis mechanisms, were modulated by these agents, either individually or in combination. Most studies used cancer cells in vitro with the goal of modifying their phenotype by changing miRNA expression profiles. In vivo studies evaluated regulation of miRNAs by chemopreventive agents in organs of mice and rats, either untreated or exposed to carcinogens, with the objective of evaluating their safety and efficacy. The tissue specificity of miRNAs could be exploited for the chemoprevention of site-specific cancers, and the study of polymorphic miRNAs is expected to predict the individual response to chemopreventive agents as a tool for developing new prevention strategies. PMID:22683846

Modeling the Population Dynamics of Antibiotic-Resistant Bacteria:. AN Agent-Based Approach

NASA Astrophysics Data System (ADS)

Murphy, James T.; Walshe, Ray; Devocelle, Marc

The response of bacterial populations to antibiotic treatment is often a function of a diverse range of interacting factors. In order to develop strategies to minimize the spread of antibiotic resistance in pathogenic bacteria, a sound theoretical understanding of the systems of interactions taking place within a colony must be developed. The agent-based approach to modeling bacterial populations is a useful tool for relating data obtained at the molecular and cellular level with the overall population dynamics. Here we demonstrate an agent-based model, called Micro-Gen, which has been developed to simulate the growth and development of bacterial colonies in culture. The model also incorporates biochemical rules and parameters describing the kinetic interactions of bacterial cells with antibiotic molecules. Simulations were carried out to replicate the development of methicillin-resistant S. aureus (MRSA) colonies growing in the presence of antibiotics. The model was explored to see how the properties of the system emerge from the interactions of the individual bacterial agents in order to achieve a better mechanistic understanding of the population dynamics taking place. Micro-Gen provides a good theoretical framework for investigating the effects of local environmental conditions and cellular properties on the response of bacterial populations to antibiotic exposure in the context of a simulated environment.

An experimental analysis of process parameters to manufacture micro-channels in AISI H13 tempered steel by laser micro-milling

NASA Astrophysics Data System (ADS)

Teixidor, D.; Ferrer, I.; Ciurana, J.

2012-04-01

This paper reports the characterization of laser machining (milling) process to manufacture micro-channels in order to understand the incidence of process parameters on the final features. Selection of process operational parameters is highly critical for successful laser micromachining. A set of designed experiments is carried out in a pulsed Nd:YAG laser system using AISI H13 hardened tool steel as work material. Several micro-channels have been manufactured as micro-mold cavities varying parameters such as scanning speed (SS), pulse intensity (PI) and pulse frequency (PF). Results are obtained by evaluating the dimensions and the surface finish of the micro-channel. The dimensions and shape of the micro-channels produced with laser-micro-milling process exhibit variations. In general the use of low scanning speeds increases the quality of the feature in both surface finishing and dimensional.

Systems, methods, and apparatus of a low conductance silicon micro-leak for mass spectrometer inlet

NASA Technical Reports Server (NTRS)

Harpold, Dan N. (Inventor); Niemann, Hasso B. (Inventor); Jamieson, Brian G. (Inventor); Lynch, Bernard A. (Inventor)

2011-01-01

Systems, methods and apparatus are provided through which in some embodiments a mass spectrometer micro-leak includes a number of channels fabricated by semiconductor processing tools and that includes a number of inlet holes that provide access to the channels.

Systems, Methods, and Apparatus of a Low Conductance Silicon Micro-Leak for Mass Spectrometer Inlet

NASA Technical Reports Server (NTRS)

Harpold, Dan N. (Inventor); Niemann, Hasso B. (Inventor); Jamieson, Brian G. (Inventor); Lynch, Bernard A. (Inventor)

2013-01-01

Systems, methods and apparatus are provided through which in some embodiments a mass spectrometer micro-leak includes a number of channels fabricated by semiconductor processing tools and that includes a number of inlet holes that provide access to the channels.

In silico prediction of microRNAs on fluoride induced sperm toxicity in mice.

PubMed

Raghunath, Azhwar; Jeyabaskar, Dhivyalakshmi; Sundarraj, Kiruthika; Panneerselvam, Lakshmikanthan; Perumal, Ekambaram

2016-12-01

Fluorosis is an endemic global problem causing male reproductive impairment. F mediates male reproductive toxicity in mice down-regulating 63 genes involved in diverse biological processes - apoptosis, cell cycle, cell signaling, chemotaxis, electron transport, glycolysis, oxidative stress, sperm capacitation and spermatogenesis. We predicted the miRNAs down-regulating these 63 genes using TargetScan, DIANA and MicroCosm. The prediction tools identified 3059 miRNAs targeting 63 genes. Of the predicted interactions, 11 miRNAs (mmu-miR-103, -107, -122, -188a, -199a-5p, -205, -340-5p, -345-3p, -452-5p, -499, -878-3p) were commonly found in the three tools utilized and seven miRNAs (miR-9-5p, miR-511-3p, miR-7b-5p, miR-30e-5p, miR-17-5p, miR-122-5p and miR-541-5p) targeting six genes (Traf3, Rock2, Rgs8, Atp1b2, Cacna2d1 and Aldoa) were already validated experimentally in mice. The miRNA-mRNA network of the predicted miRNAs with its respective targets revealed the complex interaction within a biological process leading to sperm dysfunction on exposure to F. Our findings not only suggest that the predicted miRs furnish evidence, but also have the potential to serve as non-invasive biomarkers on F-induced sperm dysfunction. Our data contribute towards elucidating the function of miRNAs in the fluoride induced infertility. miRNA molecular pathways in F intoxication will open new avenues on the use of antagomirs in recovering fertility. Copyright © 2016 Elsevier Ltd. All rights reserved.

Exposure Assessment Tools by Approaches - Indirect Estimation (Scenario Evaluation)

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases, mode

Exposure Assessment Tools by Lifestages and Populations - General Population

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Exposure Assessment Tools by Lifestages and Populations - Occupational Workers

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Exposure Assessment Tools by Lifestages and Populations - Residential Consumers

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Exposure Assessment Tools by Tiers and Types - Aggregate and Cumulative

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Exposure Assessment Tools by Chemical Classes - Inorganics and Fibers

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

EPA EcoBox Tools by Exposure Pathways - Water and Sediment

EPA Pesticide Factsheets

Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Precision machining of advanced materials with waterjets

NASA Astrophysics Data System (ADS)

Liu, H. T.

2017-01-01

Recent advances in abrasive waterjet technology have elevated to the state that it often competes on equal footing with lasers and EDM for precision machining. Under the support of a National Science Foundation SBIR Phase II grant, OMAX has developed and commercialized micro abrasive water technology that is incorporated into a MicroMAX® JetMa- chining® Center. Waterjet technology, combined both abrasive waterjet and micro abrasive waterjet technology, is capable of machining most materials from macro to micro scales for a wide range of part size and thickness. Waterjet technology has technological and manufacturing merits that cannot be matched by most existing tools. As a cold cutting tool that creates no heat-affected zone, for example, waterjet cuts much faster than wire EDM and laser when measures to minimize a heat-affected zone are taken into account. In addition, waterjet is material independent; it cuts materials that cannot be cut or are difficult to cut otherwise. The versatility of waterjet has also demonstrated machining simulated nanomaterials with large gradients of material properties from metal, nonmetal, to anything in between. This paper presents waterjet-machined samples made of a wide range of advanced materials from macro to micro scales.

Three-dimensional murine airway segmentation in micro-CT images

NASA Astrophysics Data System (ADS)

Shi, Lijun; Thiesse, Jacqueline; McLennan, Geoffrey; Hoffman, Eric A.; Reinhardt, Joseph M.

2007-03-01

Thoracic imaging for small animals has emerged as an important tool for monitoring pulmonary disease progression and therapy response in genetically engineered animals. Micro-CT is becoming the standard thoracic imaging modality in small animal imaging because it can produce high-resolution images of the lung parenchyma, vasculature, and airways. Segmentation, measurement, and visualization of the airway tree is an important step in pulmonary image analysis. However, manual analysis of the airway tree in micro-CT images can be extremely time-consuming since a typical dataset is usually on the order of several gigabytes in size. Automated and semi-automated tools for micro-CT airway analysis are desirable. In this paper, we propose an automatic airway segmentation method for in vivo micro-CT images of the murine lung and validate our method by comparing the automatic results to manual tracing. Our method is based primarily on grayscale morphology. The results show good visual matches between manually segmented and automatically segmented trees. The average true positive volume fraction compared to manual analysis is 91.61%. The overall runtime for the automatic method is on the order of 30 minutes per volume compared to several hours to a few days for manual analysis.

Micro transflection on a metallic stick: an innovative approach of reflection infrared spectroscopy for minimally invasive investigation of painting varnishes.

PubMed

Rosi, Francesca; Legan, Lea; Miliani, Costanza; Ropret, Polonca

2017-05-01

A new analytical approach, based on micro-transflection measurements from a diamond-coated metal sampling stick, is presented for the analysis of painting varnishes. Minimally invasive sampling is performed from the varnished surface using the stick, which is directly used as a transflection substrate for micro Fourier transform infrared (FTIR) measurements. With use of a series of varnished model paints, the micro-transflection method has been proved to be a valuable tool for the identification of surface components thanks to the selectivity of the sampling, the enhancement of the absorbance signal, and the easier spectral interpretation because the profiles are similar to transmission mode ones. Driven by these positive outcomes, the method was then tested as tool supporting noninvasive reflection FTIR spectroscopy during the assessment of varnish removal by solvent cleaning on paint models. Finally, the integrated analytical approach based on the two reflection methods was successfully applied for the monitoring of the cleaning of the sixteenth century painting Presentation in the Temple by Vittore Carpaccio. Graphical Abstract Micro-transflection FTIR on a metallic stick for the identification of varnishes during painting cleanings.

Investigation on the effect of Friction Stir Processing Parameters on Micro-structure and Micro-hardness of Rice Husk Ash reinforced Al6061 Metal Matrix Composites

NASA Astrophysics Data System (ADS)

Fatchurrohman, N.; Farhana, N.; Marini, C. D.

2018-03-01

Friction stir processing (FSP) is an alternative way to produce the surface composites of aluminium alloy in order to modify the microstructure and improve the mechanical properties. In this experiment, Al6061 aluminium alloy has been chosen to be used as the matrix base plate for the FSP. Al606 has potential for the use in advanced application but it has low wear resistance. While, the reinforced used was rice husk ash (RHA) in order to produce surface composites which increased the micro hardness of the plate composites. The Al6061 was stirred individually and with 5 weight % of RHA at three different tool rotational speeds of 800 rpm, 1000 rpm and 1200 rpm. After running the FSP, the result in the distribution of particles and the micro hardness of the specimens were identified. The result showed that Al6061 plate with the existing 5 weight % of RHA reinforced at the highest of tool rotational speeds of 1200rpm has the best distribution of particles and the highest result in average of micro hardness with 80Hv.

Non-destructive imaging of fragments of historical beeswax seals using high-contrast X-ray micro-radiography and micro-tomography with large area photon-counting detector array.

PubMed

Karch, Jakub; Bartl, Benjamin; Dudak, Jan; Zemlicka, Jan; Krejci, Frantisek

2016-12-01

Historical beeswax seals are unique cultural heritage objects. Unfortunately, a number of historical sealing waxes show a porous structure with a strong tendency to stratification and embrittlement, which makes these objects extremely prone to mechanical damage. The understanding of beeswax degradation processes therefore plays an important role in the preservation and consequent treatment of these objects. Conventional methods applied for the investigation of beeswax materials (e.g. gas chromatography) are of a destructive nature or bring only limited information about the sample surface (microscopic techniques). Considering practical limitations of conventional methods and ethical difficulties connected with the sampling of the historical material, radiation imaging methods such as X-ray micro-tomography presents a promising non-destructive tool for the onward scientific research in this field. In this contribution, we present the application of high-contrast X-ray micro-radiography and micro-tomography for the investigation of beeswax seal fragments. The method is based on the application of the large area photon-counting detector recently developed at our institute. The detector combines the advantages of single-photon counting technology with a large field of view. The method, consequently, enables imaging of relatively large objects with high geometrical magnification. In the reconstructed micro-tomographies of investigated historical beeswax seals, we are able to reveal morphological structures such as stratification, micro-cavities and micro-fractures with spatial resolution down to 5μm non-destructively and with high imaging quality. The presented work therefore demonstrates that a combination of state-of-the-art hybrid pixel semiconductor detectors and currently available micro-focus x-ray sources makes it possible to apply X-ray micro-radiography and micro-tomography as a valuable non-destructive tool for volumetric beeswax seal morphological studies. Copyright © 2016 Elsevier Ltd. All rights reserved.

SMART micro-scissors with dual motors and OCT sensors (Conference Presentation)

NASA Astrophysics Data System (ADS)

Yeo, Chaebeom; Jang, Seonjin; Park, Hyun-cheol; Gehlbach, Peter L.; Song, Cheol

2017-02-01

Various end-effectors of microsurgical instruments have been developed and studied. Also, many approaches to stabilize the tool-tip using robotics have been studied such as the steady hand robot system, Micron, and SMART system. In our previous study, the horizontal SMART micro-scissors with a common path swept source OCT distance and one linear piezoelectric (PZT) motor was demonstrated as a microsurgical system. Because the outer needle is connected with a mechanical handle and moved to engage the tool tip manually, the tool tip position is instantaneously changed during the engaging. The undesirable motion can make unexpected tissue damages and low surgical accuracy. In this study, we suggest a prototype horizontal SMART micro-scissors which has dual OCT sensors and two motors to improve the tremor cancellation. Dual OCT sensors provide two distance information. Front OCT sensor detects a distance from the sample surface to the tool tip. Rear OCT sensors gives current PZT motor movement, acting like a motor encoder. The PZT motor can compensate the hand tremor with a feedback loop control. The manual engaging of tool tip in previous SMART system is replaced by electrical engaging using a squiggle motor. Compared with previous study, this study showed better performance in the hand tremor reduction. From the result, the SMART with automatic engaging may become increasingly valuable in microsurgical instruments.

Exploring the potential role of tungsten carbide cobalt (WC-Co) nanoparticle internalization in observed toxicity toward lung epithelial cells in vitro.

PubMed

Armstead, Andrea L; Arena, Christopher B; Li, Bingyun

2014-07-01

Tungsten carbide cobalt (WC-Co) has been recognized as a workplace inhalation hazard in the manufacturing, mining and drilling industries by the National Institute of Occupational Safety and Health. Exposure to WC-Co is known to cause "hard metal lung disease" but the relationship between exposure, toxicity and development of disease remain poorly understood. To better understand this relationship, the present study examined the role of WC-Co particle size and internalization on toxicity using lung epithelial cells. We demonstrated that nano- and micro-WC-Co particles exerted toxicity in a dose- and time-dependent manner and that nano-WC-Co particles caused significantly greater toxicity at lower concentrations and shorter exposure times compared to micro-WC-Co particles. WC-Co particles in the nano-size range (not micron-sized) were internalized by lung epithelial cells, which suggested that internalization may play a key role in the enhanced toxicity of nano-WC-Co particles over micro-WC-Co particles. Further exploration of the internalization process indicated that there may be multiple mechanisms involved in WC-Co internalization such as actin and microtubule based cytoskeletal rearrangements. These findings support our hypothesis that WC-Co particle internalization contributes to cellular toxicity and suggest that therapeutic treatments inhibiting particle internalization may serve as prophylactic approaches for those at risk of WC-Co particle exposure. Copyright © 2014 Elsevier Inc. All rights reserved.

The Language Exposure Assessment Tool: Quantifying Language Exposure in Infants and Children

ERIC Educational Resources Information Center

DeAnda, Stephanie; Bosch, Laura; Poulin-Dubois, Diane; Zesiger, Pascal; Friend, Margaret

2016-01-01

Purpose: The aim of this study was to develop the Language Exposure Assessment Tool (LEAT) and to examine its cross-linguistic validity, reliability, and utility. The LEAT is a computerized interview-style assessment that requests parents to estimate language exposure. The LEAT yields an automatic calculation of relative language exposure and…

Exposure Assessment Tools by Tiers and Types - Screening-Level and Refined

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Exposure Assessment Tools by Approaches - Direct Measurement (Point-of-Contact Measurement)

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases, mode

Exposure Assessment Tools by Tiers and Types - Deterministic and Probabilistic Assessments

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

A small whole-body exposure chamber for laboratory use.

PubMed

O'Shaughnessy, Patrick T; Achutan, Chandran; O'Neill, Marsha E; Thorne, Peter S

2003-03-01

With the development of transgenic and specialized mouse strains, there is an increased need for inhalation exposure systems designed for smaller exposure groups. An inhalation exposure chamber, designed specifically for the exposure of up to 40 mice, was characterized. The chamber was fabricated from 0.32-cm-thick ((1)/(8)-in) aluminum sheets with outside dimensions of 61 cm long by 32 cm high by 34 cm deep, resulting in an internal volume of 65 L. Two stainless-steel open-mesh cages, separated by an absorbent barrier, can be stacked within the central portion of the chamber. Access is provided through a gasketed door with a safety-glass face. Tests were performed to determine the chamber leakage rate, degree of mixing, and spatial variation of two aerosols within the chamber. Results indicated that the fractional leakage rate was 0.0003 min(-1), well below a reported criterion for an operating chamber. Chamber operation gave similar mixing performance with, or without, use of an interior fan. For aerosols with a mass median aerodynamic diameter (MMAD) of 2.56 micro m and 3.14 micro m, the spatial variation of particulate matter concentration resulted in coefficients of variation (CVs) of 4.8% and 11.0%, respectively. These CV values are comparable to those obtained from similar studies involving other inhalation exposure chambers.

The function of prehistoric lithic tools: a combined study of use-wear analysis and FTIR microspectroscopy.

PubMed

Nunziante Cesaro, Stella; Lemorini, Cristina

2012-02-01

The application of combined use-wear analysis and FTIR micro spectroscopy for the investigation of the flint and obsidian tools from the archaeological sites of Masseria Candelaro (Foggia, Italy) and Sant'Anna di Oria (Brindisi, Italy) aiming to clarify their functional use is described. The tools excavated in the former site showed in a very high percentage spectroscopically detectable residues on their working edges. The identification of micro deposits is based on comparison with a great number of replicas studied in the same experimental conditions. FTIR data confirmed in almost all cases the use-wear analysis suggestions and added details about the material processed and about the working procedures. Copyright © 2011 Elsevier B.V. All rights reserved.

Medications as a source of human exposure to phthalates.

PubMed Central

Hauser, Russ; Duty, Susan; Godfrey-Bailey, Linda; Calafat, Antonia M

2004-01-01

Phthalates are a group of multifunctional chemicals used in consumer and personal care products, plastics, and medical devices. Laboratory studies show that some phthalates are reproductive and developmental toxicants. Recently, human studies have shown measurable levels of several phthalates in most of the U.S. general population. Despite their widespread use and the consistent toxicologic data on phthalates, information is limited on sources and pathways of human exposure to phthalates. One potential source of exposure is medications. The need for site-specific dosage medications has led to the use of enteric coatings that allow the release of the active ingredients into the small intestine or in the colon. The enteric coatings generally consist of various polymers that contain plasticizers, including triethyl citrate, dibutyl sebacate, and phthalates such as diethyl phthalate (DEP) and dibutyl phthalate (DBP). In this article we report on medications as a potential source of exposure to DBP in a man who took Asacol [active ingredient mesalamine (mesalazine)] for the treatment of ulcerative colitis. In a spot urine sample from this man collected 3 months after he started taking Asacol, the concentration of monobutyl phthalate, a DBP metabolite, was 16,868 ng/mL (6,180 micro g/g creatinine). This concentration was more than two orders of magnitude higher than the 95th percentile for males reported in the 1999-2000 National Health and Nutrition Examination Survey (NHANES). The patient's urinary concentrations of monoethyl phthalate (443.7 ng/mL, 162.6 micro g/g creatinine), mono-2-ethylhexyl phthalate (3.0 ng/mL, 1.1 micro g/g creatinine), and monobenzyl phthalate (9.3 ng/mL, 3.4 micro g/g creatinine) were unremarkable compared with the NHANES 1999-2000 values. Before this report, the highest estimated human exposure to DBP was more than two orders of magnitude lower than the no observable adverse effect level from animal studies. Further research is necessary to determine the proportional contribution of medications, as well as personal care and consumer products, to a person's total phthalate burden. PMID:15121520

Effects of tributyltin (TBT) on in vitro hormonal and biotransformation responses in Atlantic salmon (Salmo salar).

PubMed

Mortensen, Anne S; Arukwe, Augustine

2009-01-01

The mechanisms by which the biocide tributyltin (TBT) and its metabolites affect the hormonal and xenobiotic biotransformation pathways in aquatic species are not well understood. In this study hepatocytes isolated from salmon were used to evaluate the mechanistical effects of TBT on fish hormonal and xenobiotic biotransformation pathways. Cells were exposed to 0.01, 0.1, 1, or 5 microM TBT and samples were collected at 0, 12, 24, or 48 h following exposure. Gene expression patterns were evaluated using quantitative polymerase chain reaction (PCR), and cytochrome P-450 (CYP)-mediated enzyme activities were evaluated by ethoxyresorufin, benzyloxyresorufin, and pentoxyresorufin O-deethylase (EROD, BROD, and PROD, respectively) activity assays. Generally, exposure of hepatocytes to 1 microM (at 48 h) and 5 microM TBT (at 12, 24, and 48 h) consistently produced reductions in all mRNA species investigated. TBT produced significant decreases of vitellogen (Vtg) expression at 48 h and modified the expression patterns of estrogen receptors (ERalpha and ERbeta) and androgen receptor-beta (ARbeta) that were dependent on time and TBT concentration. In the xenobiotic biotransformation pathway, TBT produced differential expression patterns that were dependent on exposure time and concentration for all salmonid AhR2 isoforms (AhR2alpha, AhR2beta, AhR2delta, and AhR2gamma). For CYP1A1, CYP3A, AhRR, and Arnt mRNA, TBT produced exposure- and time-specific modulations. Catalytic CYP activities showed that BROD activity increased in an apparent concentration-specific manner in cells exposed to TBT for 12 h. Interestingly, EROD activity showed a TBT concentration-dependent increase at 24 h and PROD at 12 and 48 h of exposure. In general our data show that TBT differentially modulated hormonal and biotransformation responses in the salmon in vitro system. The apparent and consistent decrease of the studied responses with time in 1 and 5 microM exposed hepatocytes suggest a possible transcription inhibitory effect of TBT.

[Coupling AFM fluid imaging with micro-flocculation filtration process for the technological optimization].

PubMed

Zheng, Bei; Ge, Xiao-peng; Yu, Zhi-yong; Yuan, Sheng-guang; Zhang, Wen-jing; Sun, Jing-fang

2012-08-01

Atomic force microscope (AFM) fluid imaging was applied to the study of micro-flocculation filtration process and the optimization of micro-flocculation time and the agitation intensity of G values. It can be concluded that AFM fluid imaging proves to be a promising tool in the observation and characterization of floc morphology and the dynamic coagulation processes under aqueous environmental conditions. Through the use of AFM fluid imaging technique, optimized conditions for micro-flocculation time of 2 min and the agitation intensity (G value) of 100 s(-1) were obtained in the treatment of dye-printing industrial tailing wastewater by the micro-flocculation filtration process with a good performance.

A Data-Driven Framework for Incorporating New Tools for ...

EPA Pesticide Factsheets

This talk was given during the “Exposure-Based Toxicity Testing” session at the annual meeting of the International Society for Exposure Science. It provided an update on the state of the science and tools that may be employed in risk-based prioritization efforts. It outlined knowledge gained from the data provided using these high-throughput tools to assess chemical bioactivity and to predict chemical exposures and also identified future needs. It provided an opportunity to showcase ongoing research efforts within the National Exposure Research Laboratory and the National Center for Computational Toxicology within the Office of Research and Development to an international audience. The National Exposure Research Laboratory (NERL) Computational Exposure Division (CED) develops and evaluates data, decision-support tools, and models to be applied to media-specific or receptor-specific problem areas. CED uses modeling-based approaches to characterize exposures, evaluate fate and transport, and support environmental diagnostics/forensics with input from multiple data sources. It also develops media- and receptor-specific models, process models, and decision support tools for use both within and outside of EPA.

Exposure Assessment Tools by Lifestages and Populations - Highly Exposed or Other Susceptible Population Groups

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Data Exploration using Unsupervised Feature Extraction for Mixed Micro-Seismic Signals

NASA Astrophysics Data System (ADS)

Meyer, Matthias; Weber, Samuel; Beutel, Jan

2017-04-01

We present a system for the analysis of data originating in a multi-sensor and multi-year experiment focusing on slope stability and its underlying processes in fractured permafrost rock walls undertaken at 3500m a.s.l. on the Matterhorn Hörnligrat, (Zermatt, Switzerland). This system incorporates facilities for the transmission, management and storage of large-scales of data ( 7 GB/day), preprocessing and aggregation of multiple sensor types, machine-learning based automatic feature extraction for micro-seismic and acoustic emission data and interactive web-based visualization of the data. Specifically, a combination of three types of sensors are used to profile the frequency spectrum from 1 Hz to 80 kHz with the goal to identify the relevant destructive processes (e.g. micro-cracking and fracture propagation) leading to the eventual destabilization of large rock masses. The sensors installed for this profiling experiment (2 geophones, 1 accelerometers and 2 piezo-electric sensors for detecting acoustic emission), are further augmented with sensors originating from a previous activity focusing on long-term monitoring of temperature evolution and rock kinematics with the help of wireless sensor networks (crackmeters, cameras, weather station, rock temperature profiles, differential GPS) [Hasler2012]. In raw format, the data generated by the different types of sensors, specifically the micro-seismic and acoustic emission sensors, is strongly heterogeneous, in part unsynchronized and the storage and processing demand is large. Therefore, a purpose-built signal preprocessing and event-detection system is used. While the analysis of data from each individual sensor follows established methods, the application of all these sensor types in combination within a field experiment is unique. Furthermore, experience and methods from using such sensors in laboratory settings cannot be readily transferred to the mountain field site setting with its scale and full exposure to the natural environment. Consequently, many state-of-the-art algorithms for big data analysis and event classification requiring a ground truth dataset cannot be applied. The above mentioned challenges require a tool for data exploration. In the presented system, data exploration is supported by unsupervised feature learning based on convolutional neural networks, which is used to automatically extract common features for preliminary clustering and outlier detection. With this information, an interactive web-tool allows for a fast identification of interesting time segments on which segment-selective algorithms for visualization, feature extraction and statistics can be applied. The combination of manual labeling based and unsupervised feature extraction provides an event catalog for classification of different characteristic events related to internal progression of micro-crack in steep fractured bedrock permafrost. References Hasler, A., S. Gruber, and J. Beutel (2012), Kinematics of steep bedrock permafrost, J. Geophys. Res., 117, F01016, doi:10.1029/2011JF001981.

Diazoxide triggers cardioprotection against apoptosis induced by oxidative stress.

PubMed

Ichinose, Masashi; Yonemochi, Hidetoshi; Sato, Toshiaki; Saikawa, Tetsunori

2003-06-01

Although mitochondrial ATP-sensitive potassium (mitoK(ATP)) channels have been reported to reduce the extent of apoptosis, the critical timing of mitoK(ATP) channel opening required to protect myocytes against apoptosis remains unclear. In the present study, we examined whether the mitoK(ATP) channel serves as a trigger of cardioprotection against apoptosis induced by oxidative stress. Apoptosis of cultured neonatal rat cardiomyocytes was determined by flow cytometry (light scatter and propidium iodide/annexin V-FITC fluorescence) and by nuclear staining with Hoechst 33342. Mitochondrial membrane potential (DeltaPsi) was measured by flow cytometry of cells stained with rhodamine-123 (Rh-123). Exposure to H(2)O(2) (500 microM) induced apoptosis, and the percentage of apoptotic cells increased progressively and peaked at 2 h. This H(2)O(2)-induced apoptosis was associated with the loss of DeltaPsi, and the time course of decrease in Rh-123 fluorescence paralleled that of apoptosis. Pretreatment of cardiomyocytes with diazoxide (100 microM), a putative mitoK(ATP) channel opener, for 30 min before exposure to H(2)O(2) elicited transient and mild depolarization of DeltaPsi and consequently suppressed both apoptosis and DeltaPsi loss after 2-h exposure to H(2)O(2). These protective effects of diazoxide were abrogated by the mitoK(ATP) channel blocker 5-hydroxydecanoate (500 microM) but not by the sarcolemmal K(ATP) channel blocker HMR-1098 (30 microM). Our results suggest for the first time that diazoxide-induced opening of mitoK(ATP) channels triggers cardioprotection against apoptosis induced by oxidative stress in rat cardiomyocytes.

The influence of street layouts and viaduct settings on daily carbon monoxide exposure and intake fraction in idealized urban canyons.

PubMed

Hang, Jian; Luo, Zhiwen; Wang, Xuemei; He, Lejian; Wang, Baomin; Zhu, Wei

2017-01-01

Environmental concerns have been raised on the adverse health effects of vehicle emissions in micro-scale traffic-crowded street canyons, especially for pedestrians and residents living in near-road buildings. Viaduct design is sometimes used to improve transportation efficiency but possibly affects urban airflow and the resultant exposure risk, which have been rarely investigated so far. The personal intake fraction (P_IF) is defined as the average fraction of total emissions that is inhaled by each person of a population (1 ppm = 1 × 10 -6 ), and the daily carbon monoxide (CO) pollutant exposure (E t ) is estimated by multiplying the average concentration of a specific micro-environment within one day. As a novelty, by considering time activity patterns and breathing rates in various micro-environments for three age groups, this paper introduces IF and E t into computational fluid dynamic (CFD) simulation to quantify the impacts of street layouts (street width/building height W/H = 1, 1.5, 2), source location, viaduct settings and noise barriers on the source-exposure correlation when realistic CO sources are defined. Narrower streets experience larger P_IF (1.51-5.21 ppm) and CO exposure, and leeward-side buildings always attain higher vehicular pollutant exposure than windward-side. Cases with a viaduct experience smaller P_IF (3.25-1.46 ppm) than cases without a viaduct (P_IF = 5.21-2.23 ppm) if the single ground-level CO source is elevated onto the viaduct. With two CO sources (both ground-level and viaduct-level), daily CO exposure rises 2.80-3.33 times but P_IF only change slightly. Noise barriers above a viaduct raise concentration between barriers, but slightly reduce vehicular exposure in near-road buildings. Because people spend most of their time indoors, vehicular pollutant exposure within near-road buildings can be 6-9 times that at pedestrian level. Although further studies are still required to provide practical guidelines, this paper provides effective methodologies to quantify the impacts of street/viaduct configurations on human exposure for urban design purpose. Copyright © 2016 Elsevier Ltd. All rights reserved.

Large-scale fabrication of micro-lens array by novel end-fly-cutting-servo diamond machining.

PubMed

Zhu, Zhiwei; To, Suet; Zhang, Shaojian

2015-08-10

Fast/slow tool servo (FTS/STS) diamond turning is a very promising technique for the generation of micro-lens array (MLA). However, it is still a challenge to process MLA in large scale due to certain inherent limitations of this technique. In the present study, a novel ultra-precision diamond cutting method, as the end-fly-cutting-servo (EFCS) system, is adopted and investigated for large-scale generation of MLA. After a detailed discussion of the characteristic advantages for processing MLA, the optimal toolpath generation strategy for the EFCS is developed with consideration of the geometry and installation pose of the diamond tool. A typical aspheric MLA over a large area is experimentally fabricated, and the resulting form accuracy, surface micro-topography and machining efficiency are critically investigated. The result indicates that the MLA with homogeneous quality over the whole area is obtained. Besides, high machining efficiency, extremely small volume of control points for the toolpath, and optimal usage of system dynamics of the machine tool during the whole cutting can be simultaneously achieved.

EUV lithography for 22nm half pitch and beyond: exploring resolution, LWR, and sensitivity tradeoffs

NASA Astrophysics Data System (ADS)

Putna, E. Steve; Younkin, Todd R.; Leeson, Michael; Caudillo, Roman; Bacuita, Terence; Shah, Uday; Chandhok, Manish

2011-04-01

The International Technology Roadmap for Semiconductors (ITRS) denotes Extreme Ultraviolet (EUV) lithography as a leading technology option for realizing the 22nm half pitch node and beyond. According to recent assessments made at the 2010 EUVL Symposium, the readiness of EUV materials remains one of the top risk items for EUV adoption. The main development issue regarding EUV resists has been how to simultaneously achieve high resolution, high sensitivity, and low line width roughness (LWR). This paper describes our strategy, the current status of EUV materials, and the integrated post-development LWR reduction efforts made at Intel Corporation. Data collected utilizing Intel's Micro- Exposure Tool (MET) is presented in order to examine the feasibility of establishing a resist process that simultaneously exhibits <=22nm half-pitch (HP) L/S resolution at <=11.3mJ/cm2 with <=3nm LWR.

miRToolsGallery: a tag-based and rankable microRNA bioinformatics resources database portal

PubMed Central

Chen, Liang; Heikkinen, Liisa; Wang, ChangLiang; Yang, Yang; Knott, K Emily

2018-01-01

Abstract Hundreds of bioinformatics tools have been developed for MicroRNA (miRNA) investigations including those used for identification, target prediction, structure and expression profile analysis. However, finding the correct tool for a specific application requires the tedious and laborious process of locating, downloading, testing and validating the appropriate tool from a group of nearly a thousand. In order to facilitate this process, we developed a novel database portal named miRToolsGallery. We constructed the portal by manually curating > 950 miRNA analysis tools and resources. In the portal, a query to locate the appropriate tool is expedited by being searchable, filterable and rankable. The ranking feature is vital to quickly identify and prioritize the more useful from the obscure tools. Tools are ranked via different criteria including the PageRank algorithm, date of publication, number of citations, average of votes and number of publications. miRToolsGallery provides links and data for the comprehensive collection of currently available miRNA tools with a ranking function which can be adjusted using different criteria according to specific requirements. Database URL: http://www.mirtoolsgallery.org PMID:29688355

Effects of repeated exposure to 4-nonylphenol on the zooplankton community in littoral enclosures

DOE Office of Scientific and Technical Information (OSTI.GOV)

O`Halloran, S.L.; Liber, K.; Gangl, J.A.

1999-03-01

The effects of 4-nonylphenol (NP) on freshwater zooplankton were evaluated in 18 littoral enclosure mesocosms in northeastern Minnesota. The 18 enclosures were allocated to three blocks of six units with each block including two untreated control enclosures and one enclosure for each of four NP treatments. Treated enclosures received 11 applications of NP over a 20-d period between July 8 and 28, 1993. Maximum NP concentrations measured in the water column 2 h after each application averaged ({+-} SD) 5 {+-} 4, 23 {+-} 11, 76 {+-} 21, and 243 {+-} 41 {micro}g/L over the 11 applications. Nonylphenol dissipated rapidlymore » from the water column but was more persistent in sediments and in/on macrophytes. All cladoceran and copepod taxa were significantly reduced in abundance at 243 {+-} 41 {micro}g/L; some sensitive taxa were also affected by 76 {+-} 21 and 23 {+-} 11 {micro}g/L. While many rotifer taxa were unaffected at any of the test concentrations, several were affected at {ge} 76 {+-} 21 {micro}g/L. Ostracods were only affected at 2,243 {+-} 41 {micro}g/L. No zooplankton taxon was affected at 5 {+-} 4 {micro}g/L. The period of maximum impact usually occurred within 1 to 7 d of the last NP application, and recovery to control abundance levels generally occurred within 7 to 28 d of the last NP application. Two sensitive taxa, Acroperus and Calanoida, did not recover at {ge} 76 {+-} 21 {micro}g/L by the end of the study. The maximum acceptable toxicant concentration for protection of all zooplankton taxa was estimated at {approximately} 10 {micro}g/L, although overall community diversity was unaffected at 23 {+-} 11. The water was the most probable route of NP exposure, but the greater persistence of NP residues in/on macrophytes may have contributed to the lack of recovery of some macrophyte-associated taxa.« less

Minimally Invasive Radiation Biodosimetry and Evaluation of Organ Responses

DTIC Science & Technology

2016-10-01

radiation exposure, potentially leading to Acute Radiation Syndromes (ARS) and Delayed Effects of Acute ...underlying conditions and inherent variations. 2. KEYWORDS Radiation Biodosimetry, Radiation Biomarkers, microRNA, Acute Radiation Syndromes ... syndromes and delayed effects of acute radiation exposure. We expect to identify the circulating miRNA biomarkers as early predictors of late effects

Laboratory and exterior decay of wood plastic composite boards: voids analysis and computed tomography

Treesearch

Grace Sun; Rebecca E. Ibach; Meghan Faillace; Marek Gnatowski; Jessie A. Glaeser; John Haight

2016-01-01

After exposure in the field and laboratory soil block culture testing, the void content of wood–plastic composite (WPC) decking boards was compared to unexposed samples. A void volume analysis was conducted based on calculations of sample density and from micro-computed tomography (microCT) data. It was found that reference WPC contains voids of different sizes from...

Unified continuum damage model for matrix cracking in composite rotor blades

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pollayi, Hemaraju; Harursampath, Dineshkumar

This paper deals with modeling of the first damage mode, matrix micro-cracking, in helicopter rotor/wind turbine blades and how this effects the overall cross-sectional stiffness. The helicopter/wind turbine rotor system operates in a highly dynamic and unsteady environment leading to severe vibratory loads present in the system. Repeated exposure to this loading condition can induce damage in the composite rotor blades. These rotor/turbine blades are generally made of fiber-reinforced laminated composites and exhibit various competing modes of damage such as matrix micro-cracking, delamination, and fiber breakage. There is a need to study the behavior of the composite rotor system undermore » various key damage modes in composite materials for developing Structural Health Monitoring (SHM) system. Each blade is modeled as a beam based on geometrically non-linear 3-D elasticity theory. Each blade thus splits into 2-D analyzes of cross-sections and non-linear 1-D analyzes along the beam reference curves. Two different tools are used here for complete 3-D analysis: VABS for 2-D cross-sectional analysis and GEBT for 1-D beam analysis. The physically-based failure models for matrix in compression and tension loading are used in the present work. Matrix cracking is detected using two failure criterion: Matrix Failure in Compression and Matrix Failure in Tension which are based on the recovered field. A strain variable is set which drives the damage variable for matrix cracking and this damage variable is used to estimate the reduced cross-sectional stiffness. The matrix micro-cracking is performed in two different approaches: (i) Element-wise, and (ii) Node-wise. The procedure presented in this paper is implemented in VABS as matrix micro-cracking modeling module. Three examples are presented to investigate the matrix failure model which illustrate the effect of matrix cracking on cross-sectional stiffness by varying the applied cyclic load.« less

Surface structuring of boron doped CVD diamond by micro electrical discharge machining

NASA Astrophysics Data System (ADS)

Schubert, A.; Berger, T.; Martin, A.; Hackert-Oschätzchen, M.; Treffkorn, N.; Kühn, R.

2018-05-01

Boron doped diamond materials, which are generated by Chemical Vapor Deposition (CVD), offer a great potential for the application on highly stressed tools, e. g. in cutting or forming processes. As a result of the CVD process rough surfaces arise, which require a finishing treatment in particular for the application in forming tools. Cutting techniques such as milling and grinding are hardly applicable for the finish machining because of the high strength of diamond. Due to its process principle of ablating material by melting and evaporating, Electrical Discharge Machining (EDM) is independent of hardness, brittleness or toughness of the workpiece material. EDM is a suitable technology for machining and structuring CVD diamond, since boron doped CVD diamond is electrically conductive. In this study the ablation characteristics of boron doped CVD diamond by micro electrical discharge machining are investigated. Experiments were carried out to investigate the influence of different process parameters on the machining result. The impact of tool-polarity, voltage and discharge energy on the resulting erosion geometry and the tool wear was analyzed. A variation in path overlapping during the erosion of planar areas leads to different microstructures. The results show that micro EDM is a suitable technology for finishing of boron doped CVD diamond.

Tomato TILLING Technology: Development of a Reverse Genetics Tool for the Efficient Isolation of Mutants from Micro-Tom Mutant Libraries

PubMed Central

Okabe, Yoshihiro; Asamizu, Erika; Saito, Takeshi; Matsukura, Chiaki; Ariizumi, Tohru; Brès, Cécile; Rothan, Christophe; Mizoguchi, Tsuyoshi; Ezura, Hiroshi

2011-01-01

To accelerate functional genomic research in tomato, we developed a Micro-Tom TILLING (Targeting Induced Local Lesions In Genomes) platform. DNA pools were constructed from 3,052 ethyl methanesulfonate (EMS) mutant lines treated with 0.5 or 1.0% EMS. The mutation frequency was calculated by screening 10 genes. The 0.5% EMS population had a mild mutation frequency of one mutation per 1,710 kb, whereas the 1.0% EMS population had a frequency of one mutation per 737 kb, a frequency suitable for producing an allelic series of mutations in the target genes. The overall mutation frequency was one mutation per 1,237 kb, which affected an average of three alleles per kilobase screened. To assess whether a Micro-Tom TILLING platform could be used for efficient mutant isolation, six ethylene receptor genes in tomato (SlETR1–SlETR6) were screened. Two allelic mutants of SlETR1 (Sletr1-1 and Sletr1-2) that resulted in reduced ethylene responses were identified, indicating that our Micro-Tom TILLING platform provides a powerful tool for the rapid detection of mutations in an EMS mutant library. This work provides a practical and publicly accessible tool for the study of fruit biology and for obtaining novel genetic material that can be used to improve important agronomic traits in tomato. PMID:21965606

Tomato TILLING technology: development of a reverse genetics tool for the efficient isolation of mutants from Micro-Tom mutant libraries.

PubMed

Okabe, Yoshihiro; Asamizu, Erika; Saito, Takeshi; Matsukura, Chiaki; Ariizumi, Tohru; Brès, Cécile; Rothan, Christophe; Mizoguchi, Tsuyoshi; Ezura, Hiroshi

2011-11-01

To accelerate functional genomic research in tomato, we developed a Micro-Tom TILLING (Targeting Induced Local Lesions In Genomes) platform. DNA pools were constructed from 3,052 ethyl methanesulfonate (EMS) mutant lines treated with 0.5 or 1.0% EMS. The mutation frequency was calculated by screening 10 genes. The 0.5% EMS population had a mild mutation frequency of one mutation per 1,710 kb, whereas the 1.0% EMS population had a frequency of one mutation per 737 kb, a frequency suitable for producing an allelic series of mutations in the target genes. The overall mutation frequency was one mutation per 1,237 kb, which affected an average of three alleles per kilobase screened. To assess whether a Micro-Tom TILLING platform could be used for efficient mutant isolation, six ethylene receptor genes in tomato (SlETR1-SlETR6) were screened. Two allelic mutants of SlETR1 (Sletr1-1 and Sletr1-2) that resulted in reduced ethylene responses were identified, indicating that our Micro-Tom TILLING platform provides a powerful tool for the rapid detection of mutations in an EMS mutant library. This work provides a practical and publicly accessible tool for the study of fruit biology and for obtaining novel genetic material that can be used to improve important agronomic traits in tomato.

In-line phase contrast micro-CT reconstruction for biomedical specimens.

PubMed

Fu, Jian; Tan, Renbo

2014-01-01

X-ray phase contrast micro computed tomography (micro-CT) can non-destructively provide the internal structure information of soft tissues and low atomic number materials. It has become an invaluable analysis tool for biomedical specimens. Here an in-line phase contrast micro-CT reconstruction technique is reported, which consists of a projection extraction method and the conventional filter back-projection (FBP) reconstruction algorithm. The projection extraction is implemented by applying the Fourier transform to the forward projections of in-line phase contrast micro-CT. This work comprises a numerical study of the method and its experimental verification using a biomedical specimen dataset measured at an X-ray tube source micro-CT setup. The numerical and experimental results demonstrate that the presented technique can improve the imaging contrast of biomedical specimens. It will be of interest for a wide range of in-line phase contrast micro-CT applications in medicine and biology.

Phases of ERA - Tools

EPA Pesticide Factsheets

Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Acute effects on pulmonary function in young healthy adults exposed to traffic-related air pollution in semi-closed transport hub in Beijing.

PubMed

Huang, Jing; Deng, Furong; Wu, Shaowei; Zhao, Yan; Shima, Masayuki; Guo, Bin; Liu, Qichen; Guo, Xinbiao

2016-09-01

Transport hub is an important part of urban comprehensive transportation system. Traffic-related air pollution can reach high level because of difficulty of diffusion and increase of emission in transport hub. However, whether exposure in this semi-closed traffic micro-environment causes acute changes in pulmonary function of commuters still needs to be explored. Forty young healthy adults participated in this randomized, crossover study. Each participant underwent 2 h exposure in a designated transport hub and, on a separate occasion, in an appointed park. Personal exposures to fine particulate matter (PM 2.5 ), black carbon (BC) and carbon monoxide (CO) were measured. Forced expiratory volume in 1 s (FEV 1 ) and peak expiratory flow (PEF) were assessed pre-, during and post-exposure. Mixed linear models were used to analyze the pulmonary effects of traffic-related air pollutants. Participants had significantly higher exposures to PM 2.5 , BC and CO in the transport hub than in the park. Exposure in transport hub induced significant reductions in FEV 1 and PEF compared with the park during exposure 1 and 2 h. The reductions were significant associated with traffic-related air pollutants. For instance, per 10 μg/m 3 increment in PM 2.5 was associated with -0.15 % (95 % CI -0.28, -0.02 %) reduction in FEV 1 during exposure 2 h. However, effects became attenuate after 2 h exposure. Short-term exposure in transport hub had acute reduction effects on pulmonary function. More attention should be paid to the health effects of exposure in the semi-closed traffic micro-environment.

Facile fabrication of mesoporous silica micro-jets with multi-functionalities† †Electronic supplementary information (ESI) available: Detailed BET experiments, videos and supplementary data. See DOI: 10.1039/c7nr04527a

PubMed Central

Vilela, D.; Hortelao, A. C.; Balderas-Xicohténcatl, R.; Hirscher, M.; Hahn, K.

2017-01-01

Self-propelled micro/nano-devices have been proved as powerful tools in various applications given their capability of both autonomous motion and on-demand task fulfilment. Tubular micro-jets stand out as an important member in the family of self-propelled micro/nano-devices and are widely explored with respect to their fabrication and functionalization. A few methods are currently available for the fabrication of tubular micro-jets, nevertheless there is still a demand to explore the fabrication of tubular micro-jets made of versatile materials and with the capability of multi-functionalization. Here, we present a facile strategy for the fabrication of mesoporous silica micro-jets (MSMJs) for tubular micromotors which can carry out multiple tasks depending on their functionalities. The synthesis of MSMJs does not require the use of any equipment, making it facile and cost-effective for future practical use. The MSMJs can be modified inside, outside or both with different kinds of metal nanoparticles, which provide these micromotors with a possibility of additional properties, such as the anti-bacterial effect by silver nanoparticles, or biochemical sensing based on surface enhanced Raman scattering (SERS) by gold nanoparticles. Because of the high porosity, high surface area and also the easy surface chemistry process, the MSMJs can be employed for the efficient removal of heavy metals in contaminated water, as well as for the controlled and active drug delivery, as two proof-of-concept examples of environmental and biomedical applications, respectively. Therefore, taking into account the new, simple and cheap method of fabrication, highly porous structure, and multiple functionalities, the mesoporous silica based micro-jets can serve as efficient tools for desired applications. PMID:28891580

Micro Dot Patterning on the Light Guide Panel Using Powder Blasting

PubMed Central

Jang, Ho Su; Cho, Myeong Woo; Park, Dong Sam

2008-01-01

This study is to develop a micromachining technology for a light guide panel(LGP) mold, whereby micro dot patterns are formed on a LGP surface by a single injection process instead of existing screen printing processes. The micro powder blasting technique is applied to form micro dot patterns on the LGP mold surface. The optimal conditions for masking, laminating, exposure, and developing processes to form the micro dot patterns are first experimentally investigated. A LGP mold with masked micro patterns is then machined using the micro powder blasting method and the machinability of the micro dot patterns is verified. A prototype LGP is test- injected using the developed LGP mold and a shape analysis of the patterns and performance testing of the injected LGP are carried out. As an additional approach, matte finishing, a special surface treatment method, is applied to the mold surface to improve the light diffusion characteristics, uniformity and brightness of the LGP. The results of this study show that the applied powder blasting method can be successfully used to manufacture LGPs with micro patterns by just single injection using the developed mold and thereby replace existing screen printing methods. PMID:27879740

EUV focus sensor: design and modeling

NASA Astrophysics Data System (ADS)

Goldberg, Kenneth A.; Teyssier, Maureen E.; Liddle, J. Alexander

2005-05-01

We describe performance modeling and design optimization of a prototype EUV focus sensor (FS) designed for use with existing 0.3-NA EUV projection-lithography tools. At 0.3-NA and 13.5-nm wavelength, the depth of focus shrinks to 150 nm increasing the importance of high-sensitivity focal-plane detection tools. The FS is a free-standing Ni grating structure that works in concert with a simple mask pattern of regular lines and spaces at constant pitch. The FS pitch matches that of the image-plane aerial-image intensity: it transmits the light with high efficiency when the grating is aligned with the aerial image laterally and longitudinally. Using a single-element photodetector, to detect the transmitted flux, the FS is scanned laterally and longitudinally so the plane of peak aerial-image contrast can be found. The design under consideration has a fixed image-plane pitch of 80-nm, with aperture widths of 12-40-nm (1-3 wave-lengths), and aspect ratios of 2-8. TEMPEST-3D is used to model the light transmission. Careful attention is paid to the annular, partially coherent, unpolarized illumination and to the annular pupil of the Micro-Exposure Tool (MET) optics for which the FS is designed. The system design balances the opposing needs of high sensitivity and high throughput opti-mizing the signal-to-noise ratio in the measured intensity contrast.

EUV Focus Sensor: Design and Modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldberg, Kenneth A.; Teyssier, Maureen E.; Liddle, J. Alexander

We describe performance modeling and design optimization of a prototype EUV focus sensor (FS) designed for use with existing 0.3-NA EUV projection-lithography tools. At 0.3-NA and 13.5-nm wavelength, the depth of focus shrinks to 150 nm increasing the importance of high-sensitivity focal-plane detection tools. The FS is a free-standing Ni grating structure that works in concert with a simple mask pattern of regular lines and spaces at constant pitch. The FS pitch matches that of the image-plane aerial-image intensity: it transmits the light with high efficiency when the grating is aligned with the aerial image laterally and longitudinally. Using amore » single-element photodetector, to detect the transmitted flux, the FS is scanned laterally and longitudinally so the plane of peak aerial-image contrast can be found. The design under consideration has a fixed image-plane pitch of 80-nm, with aperture widths of 12-40-nm (1-3 wavelengths), and aspect ratios of 2-8. TEMPEST-3D is used to model the light transmission. Careful attention is paid to the annular, partially coherent, unpolarized illumination and to the annular pupil of the Micro-Exposure Tool (MET) optics for which the FS is designed. The system design balances the opposing needs of high sensitivity and high throughput optimizing the signal-to-noise ratio in the measured intensity contrast.« less

Using the Wiimote to Learn MEMS in a Physics Degree Program

ERIC Educational Resources Information Center

Sánchez-Azqueta, Carlos; Gimeno, Cecilia; Celma, Santiago; Aldea, Concepción

2016-01-01

This paper describes a learning experience designed to introduce students in a Micro- and Nanosystems course in a Physics Bachelor's degree program to the use of professional tools for the design and characterization of micro-electromechanical systems (MEMS) through a specific commercial case: the MEMS used by the well-known gaming platform…

Characteristics for electrochemical machining with nanoscale voltage pulses.

PubMed

Lee, E S; Back, S Y; Lee, J T

2009-06-01

Electrochemical machining has traditionally been used in highly specialized fields, such as those of the aerospace and defense industries. It is now increasingly being applied in other industries, where parts with difficult-to-cut material, complex geometry and tribology, and devices of nanoscale and microscale are required. Electric characteristic plays a principal function role in and chemical characteristic plays an assistant function role in electrochemical machining. Therefore, essential parameters in electrochemical machining can be described current density, machining time, inter-electrode gap size, electrolyte, electrode shape etc. Electrochemical machining provides an economical and effective method for machining high strength, high tension and heat-resistant materials into complex shapes such as turbine blades of titanium and aluminum alloys. The application of nanoscale voltage pulses between a tool electrode and a workpiece in an electrochemical environment allows the three-dimensional machining of conducting materials with sub-micrometer precision. In this study, micro probe are developed by electrochemical etching and micro holes are manufactured using these micro probe as tool electrodes. Micro holes and microgroove can be accurately achieved by using nanoscale voltages pulses.

MicroRNAs: A Puzzling Tool in Cancer Diagnostics and Therapy.

PubMed

D'Angelo, Barbara; Benedetti, Elisabetta; Cimini, Annamaria; Giordano, Antonio

2016-11-01

MicroRNAs (miRNAs) constitute a dominating class of small RNAs that regulate diverse cellular functions. Due the pivotal role of miRNAs in biological processes, a deregulated miRNA expression is likely involved in human cancers. MicroRNAs possess tumor suppressor capability, as well as display oncogenic characteristics. Interestingly, miRNAs exist in various biological fluids as circulating entities. Changes in the profile of circulating miRNAs are indicative of pathophysiological conditions in human cancer. This concept has led to consider circulating miRNAs valid biomarkers in cancer diagnostics. Furthermore, current research promotes the use of miRNAs as a target in cancer therapy. However, miRNAs are an evolving research field. Although miRNAs have been demonstrated to be potentially valuable tools both in cancer diagnosis and treatment, a greater effort should be made to improve our understanding of miRNAs biology. This review describes the biology of microRNAs, emphasizing on the use of miRNAs in cancer diagnostics and therapy. Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

EPA EcoBox Tools by Stressors - Biological

EPA Pesticide Factsheets

Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

EPA EcoBox Tools by Stressors - Physical

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EPA EcoBox Tools by Stressors

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EPA EcoBox Tools by Effects - Aquatic

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EPA EcoBox Tools by Effects - References

EPA Pesticide Factsheets

Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

EPA EcoBox Tools by Stressors - References

EPA Pesticide Factsheets

Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

EPA EcoBox Tools by Stressors - Chemical

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EPA EcoBox Tools by Effects

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Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

EPA EcoBox Tools by Receptors - Biota

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Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

EPA EcoBox Tools by Receptors - References

EPA Pesticide Factsheets

Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

EPA EcoBox Tools by Effects - Terrestrial

EPA Pesticide Factsheets

Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Tools and methods for automated assembly of miniaturized gear systems

NASA Astrophysics Data System (ADS)

Nienhaus, Matthias; Ehrfeld, Wolfgang; Berg, Udo; Schmitz, Felix; Soultan, H.

2000-10-01

The assembly of gear systems with the size of a pin head is almost beyond the bound of human tactile skills. The magic formula for series fabrication of this hybrid micro systems is the automation of the assembly process. As a contribution, this paper presents and discusses three different assembly methods comprising specifically developed tools for different types of planetary gears with outer diameters of 1.9 mm. Because of the huge importance for the complete micro assembly process, particular attention will be dedicated to the feeding and magazining of the micro gear components. Starting with metallic gear wheels as bulk good, an extremely miniaturized gear system of the Wolfram type has been automatically assembled by employing the strategy of tolerance compensation movement. As a key component, a modular tong gripper with specifically adapted gripping jaws produced by LIGA technology has been used. Further detailed investigations were spend on handling and assembly of micro injection moulded gear wheels made of POM for a three state planetary gear system. One strategy, following the idea of in situ observation, focuses on the intensive use of electronic pattern recognition. Alternatively, an unusual method based on a novel plastic wafer magazine will be discussed in detail. Hereby the exact position and orientation of injection moulded micro components will be presented from the manufacturing process up to the final micro assembly procedure. By simplifying the moulding of the micro gears as well as their handling, storing and assembly, this method has the potential to revolutionize the series fabrication of products with dimensions in the microscopic range in general.

BioVLAB-MMIA: a cloud environment for microRNA and mRNA integrated analysis (MMIA) on Amazon EC2.

PubMed

Lee, Hyungro; Yang, Youngik; Chae, Heejoon; Nam, Seungyoon; Choi, Donghoon; Tangchaisin, Patanachai; Herath, Chathura; Marru, Suresh; Nephew, Kenneth P; Kim, Sun

2012-09-01

MicroRNAs, by regulating the expression of hundreds of target genes, play critical roles in developmental biology and the etiology of numerous diseases, including cancer. As a vast amount of microRNA expression profile data are now publicly available, the integration of microRNA expression data sets with gene expression profiles is a key research problem in life science research. However, the ability to conduct genome-wide microRNA-mRNA (gene) integration currently requires sophisticated, high-end informatics tools, significant expertise in bioinformatics and computer science to carry out the complex integration analysis. In addition, increased computing infrastructure capabilities are essential in order to accommodate large data sets. In this study, we have extended the BioVLAB cloud workbench to develop an environment for the integrated analysis of microRNA and mRNA expression data, named BioVLAB-MMIA. The workbench facilitates computations on the Amazon EC2 and S3 resources orchestrated by the XBaya Workflow Suite. The advantages of BioVLAB-MMIA over the web-based MMIA system include: 1) readily expanded as new computational tools become available; 2) easily modifiable by re-configuring graphic icons in the workflow; 3) on-demand cloud computing resources can be used on an "as needed" basis; 4) distributed orchestration supports complex and long running workflows asynchronously. We believe that BioVLAB-MMIA will be an easy-to-use computing environment for researchers who plan to perform genome-wide microRNA-mRNA (gene) integrated analysis tasks.

Atrocities and Confrontational Tension

PubMed Central

Klusemann, Stefan

2009-01-01

This paper presents an analysis of video-recordings and other micro-level data of the 1995 Srebrenica massacre in Bosnia-and-Herzegovina. It focuses on the sequential unfolding of micro-interactions and emotional dynamics before, and over the course of the atrocity. The paper argues that massacres have a pattern of situational emergence: local emotional dynamics are crucial to explain where and when atrocities do or do not come off and what form they take on the micro-level. It is shown that (1) micro-interactions constitute situational turning-points, towards or away from atrocities and that (2) local emotional dynamics shape the internal structure of atrocities, i.e. their internal dynamics of killings. The analysis is based on recent advances in the micro-sociology of violence by Collins, Katz, and Grossman, as well as Ekman's research tools for identifying emotional cues in micro-data. PMID:19936029

The effect of Taurolidine on adherent and floating subpopulations of melanoma cells.

PubMed

Shrayer, D P; Lukoff, H; King, T; Calabresi, P

2003-04-01

The annual incidence of malignant melanoma is estimated at 10-12 per 100000 inhabitants in countries of Central Europe and the US, with more recent estimates showing a dramatic upward trend. Taurolidine (Carter/Wallace, Cranberry, NJ) is a novel, potentially effective, antitumor chemotherapeutic agent. We hypothesized that Taurolidine could inhibit the growth, induce apoptosis, affect the cell cycle and change morphology of melanoma cells. We expected this process to be different in adherent and floating subpopulations that may be reflective of solid tumors and their metastases. Analysis of MNT-1 human and B16F10 murine melanoma cells showed that at 72 h the IC(50) of Taurolidine was 25.4+/-3.3 microM for MNT-1 human melanoma cells and 30.9+/-3.6 microM for B16F10 murine melanoma cells. Taurolidine induced DNA fragmentation of melanoma cells in a dose-dependent manner. Taurolidine (75 and 100 microM) induced 52-97% Annexin-V binding (apoptosis), respectively. Evaluation of cell cycle after 72 h exposure to Taurolidine (0-100 microM) revealed that the percentage of melanoma cells in S phase increased from 27 to 40% in the adherent subpopulation and from 33 to 49% in the floating subpopulation. Phase contrast microscopy revealed a marked swelling of melanoma cells and decreasing cell numbers in adherent subpopulation starting at 24 h with 25 microM Taurolidine. Shrinkage of cells dominated at 75-100 microM Taurolidine. Using Cytospin assay in the floating population, we observed swelling of melanoma cells induced by 25-100 micro Taurolidine and appearance of giant (multinuclear) forms resulting from exposure to 75-100 micro Taurolidine. Some floating cells with normal morphology were observed with low concentrations of Taurolidine (0-25 microM). These data show that effects of Taurolidine may be different in adherent and floating subpopulations of melanoma cells. More importantly, floating subpopulations that may contain some viable melanoma cells, may be reflective of potential metastasis after treatment of solid tumors in vivo.

Providing the Missing Link: the Exposure Science Ontology ExO

EPA Science Inventory

Although knowledge-discovery tools are new to the exposure science community, these tools are critical for leveraging exposure information to design health studies and interpret results for improved public health decisions. Standardized ontologies define relationships, allow for ...

EPA EcoBox Tools by Receptors - Habitats and Ecosystems

EPA Pesticide Factsheets

Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

EPA EcoBox Tools by Effects - Effects In ERA

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Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

EPA EcoBox Tools by Stressors - Stressors in ERA

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Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

EPA EcoBox Tools by Receptors - Receptors in ERA

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Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

EPA ExpoBox: Submit Tool Information

EPA Pesticide Factsheets

EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases, mode

Virus-Based MicroRNA Silencing in Plants1[C][W][OPEN

PubMed Central

Sha, Aihua; Zhao, Jinping; Yin, Kangquan; Tang, Yang; Wang, Yan; Wei, Xiang; Hong, Yiguo; Liu, Yule

2014-01-01

MicroRNAs (miRNAs) play pivotal roles in various biological processes across kingdoms. Many plant miRNAs have been experimentally identified or predicted by bioinformatics mining of small RNA databases. However, the functions of these miRNAs remain largely unknown due to the lack of effective genetic tools. Here, we report a virus-based microRNA silencing (VbMS) system that can be used for functional analysis of plant miRNAs. VbMS is performed through tobacco rattle virus-based expression of miRNA target mimics to silence endogenous miRNAs. VbMS of either miR172 or miR165/166 caused developmental defects in Nicotiana benthamiana. VbMS of miR319 reduced the complexity of tomato (Solanum lycopersicum) compound leaves. These results demonstrate that tobacco rattle virus-based VbMS is a powerful tool to silence endogenous miRNAs and to dissect their functions in different plant species. PMID:24296072

Control banding approaches for nanomaterials.

PubMed

Brouwer, Derk H

2012-07-01

Control banding (CB) has been developed as a pragmatic tool to manage the risk resulting from exposure to a wide variety of potentially hazardous substances in the absence of firm toxicological and exposure information. Currently, the CB approach is applied for emerging risks such as nanoparticles, by the development of various CB-based tools. Six of these are compared. Despite their similarity, i.e. combining hazard and exposure into control or risk bands, the structure, the applicability domains, and the assignment of the hazard and exposure bands, show differences that may affect the consistency of the resulting outcome amongst the various CB tools. The value of the currently available CB tools for nanomaterials can be enhanced by transparently elucidating these differences for user consideration during the selection of a tool for a specific scenario of application.

Environmental Stressors and Their Impact on Health and Disease with Focus on Oxidative Stress.

PubMed

Münzel, Thomas; Daiber, Andreas

2018-03-20

Epidemiological, preclinical and interventional clinical studies have demonstrated that environmental stressors are associated with health problems, namely cardiovascular diseases. According to estimations of the World Health Organization (WHO), environmental risk factors account for an appreciable part of global deaths and life years spent with disability. This Forum addresses the impact of the environmental risk factors such as traffic noise exposure, air pollution by particulate matter (PM), mental stress/loneliness, and the life style risk factor (water-pipe) smoking on health and disease with focus on the cardiovascular system. We will critically discuss the use of observatory/modifiable biomarkers of oxidative stress and inflammation in environmental research on the aforementioned risk factors highlighting the need of exposome studies. Another focus will be on the epigenetic regulation via microRNAs in environmental stress upon exposure to noise and toxins/heavy metals as well as mental stress conditions, providing mechanistic insights into the modulation of microRNA signaling by oxidative stress, and vice versa the contribution of microRNAs to oxidative stress conditions. We will also provide an in-depth overview on the mechanistic pathways that lead to health problems (e.g., cardiovascular diseases) in response to environmental psychosocial stress, air pollution exposure in the form of ambient PM and diesel exhaust, traffic noise exposure, and the life style drug (water-pipe) smoking. Almost all stressors share the activation of the hypothalamic-pituitary-adrenocortical axis and of the sympathetic nervous system with subsequent onset of inflammation and oxidative stress, defining the here proposed therapeutic (antioxidant and exercise) strategies. Antioxid. Redox Signal. 28, 735-740.

Vulnerability of employees in businesses with fewer than five workers (micro-enterprises) to occupational safety and health problems.

PubMed

Park, Jungsun; Park, Jong-Shik; Han, Boyoung; Kim, Yangho

2017-12-01

We assessed the characteristics of micro-enterprises (businesses with fewer than five workers) focusing on occupational safety and health (OSH) issues. We performed a secondary analysis of data from the Economically Active Population Supplementary Survey and the fourth Korean Working Conditions Survey of 2014. Relative to larger businesses, micro-enterprises employ more women, temporary workers, and older workers (>55 years). In addition, more workers in micro-enterprises held "elementary occupations" (unskilled or under-skilled) or "sales and service jobs." Key sectors of such employment included the sectors of "wholesale and retail trade" and "hotel and restaurants." Furthermore, lower skilled workers in such micro-enterprises more frequently reported exposure to ergonomic risk factors and subsequent musculoskeletal disorders, and they also experienced a much higher fatality rate due to occupational injuries. Our results indicate that Korean workers in micro-enterprises are more vulnerable to OSH problems than workers in larger businesses. © 2017 Wiley Periodicals, Inc.

A Java tool for dynamic web-based 3D visualization of anatomy and overlapping gene or protein expression patterns.

PubMed

Gerth, Victor E; Vize, Peter D

2005-04-01

The Gene Expression Viewer is a web-launched three-dimensional visualization tool, tailored to compare surface reconstructions of multi-channel image volumes generated by confocal microscopy or micro-CT.

Mechanism of amino acid interaction with silicon nitride surface during chemical mechanical planarization

NASA Astrophysics Data System (ADS)

America, William George

Chemical-Mechanical Planarization (CMP) has become an essential technology for making modern semiconductor devices. This technique was originally applied to overcome the depth of focus limitations of lithography tools during pattern development of metal and dielectric films. As features of the semiconductor device became smaller the lithographic process shifted to shorter exposure wavelengths and the useable depth of focus became smaller. The topography differences on the wafer's surface from all of the previous processing steps became greater than the exposure tools could properly project. CMP helped solve this problem by bringing the features of the wafer surface to the same plane. As semiconductor fabrication technology progressed further, CMP was applied to other areas of the process, including shallow trench isolation and metal line Damascene processing. In its simplest application, CMP polishes on features projecting upward and higher than the average surface. These projections experience more work and are polished faster. Given sufficient time the surface becomes essentially flat, on a micro-scale, and the lithographic projection tools has the same plane onto which to focus. Thus, the pattern is properly and uniformly exposed and subsequent reactive ion etching (RIE) steps are executed. This technique was initially applied to later steps in the wafer processing scheme to render a new flat surface at each metal layer. Building on this success, CMP has been applied to a broad range of steps in the wafer processing particularly where surface topography warrants and when RIE of dielectric or metallic films is not practical. CMP has seen its greatest application in semiconductor logic and memory devices and most recently, a Damascene processing for copper lines and shallow trench isolation. This pattern dependent CMP issue is explored in this thesis as it pertains primarily to shallow trench isolation CMP coupled with a highly selective slurry chemistry.

Prenatal arsenic exposure alters REST/NRSF and microRNA regulators of embryonic neural stem cell fate in a sex-dependent manner

PubMed Central

Tyler, Christina R.; Labrecque, Matthew T.; Solomon, Elizabeth R.; Guo, Xun; Allan, Andrea M.

2016-01-01

Exposure to arsenic, a common environmental toxin found in drinking water, leads to a host of neurological pathologies. We have previously demonstrated that developmental exposure to a low level of arsenic (50 ppb) alters epigenetic processes that underlie deficits in adult hippocampal neurogenesis leading to aberrant behavior. It is unclear if arsenic impacts the programming and regulation of embryonic neurogenesis during development when exposure occurs. The master negative regulator of neural-lineage, REST/NRSF, controls the precise timing of fate specification and differentiation of neural stem cells (NSCs). Early in development (embryonic day 14), we observed increased expression of Rest, its co-repressor, CoREST, and the inhibitory RNA binding/splicing protein, Ptbp1, and altered expression of mRNA spliced isoforms of Pbx1 that are directly regulated by these factors in the male brain in response to prenatal 50 ppb arsenic exposure. These increases were concurrent with decreased expression of microRNA-9 (miR-9), miR-9*, and miR-124, all of which are REST/NRSF targets and inversely regulate Rest expression to allow for maturation of NSCs. Exposure to arsenic decreased the formation of neuroblasts in vitro from NSCs derived from male pup brains. The female response to arsenic was limited to increased expression of CoREST and Ptbp2, an RNA binding protein that allows for appropriate splicing of genes involved in the progression of neurogenesis. These changes were accompanied by increased neuroblast formation in vitro from NSCs derived from female pups. Unexposed male mice express transcriptomic factors to induce differentiation earlier in development compared to unexposed females. Thus, arsenic exposure likely delays differentiation of NSCs in males while potentially inducing precocious differentiation in females early in development. These effects are mitigated by embryonic day 18 of development. Arsenic-induced dysregulation of the regulatory loop formed by REST/NRSF, its target microRNAs, miR-9 and miR-124, and RNA splicing proteins, PTBP1 and 2, leads to aberrant programming of NSC function that is perhaps perpetuated into adulthood inducing deficits in differentiation we have previously observed. PMID:27751817

Effect of Tube-Based X-Ray Microtomography Imaging on the Amino Acid and Amine Content of the Murchison CM2 Chondrite

NASA Technical Reports Server (NTRS)

Glavin, D. P.; Friedrich, J. M.; Aponte, J. C.; Dworkin, J. P.; Ebel, D. S.; Elsila, J. E.; Hill, M.; McLain, H. L.; Towbin, W. H.

2017-01-01

X-ray and synchrotron X-ray micro-computed tomography (micro-CT) are increasingly being used for three dimensional reconnaissance imaging of chondrites and returned extraterrestrial material prior to detailed chemical and mineralogical analyses. Although micro-CT imaging is generally considered to be a non-destructive technique since silicate and metallic minerals in chondrites are not affected by X-ray exposures at the intensities and wavelengths typically used, there are concerns that the use of micro-CT could be detrimental to the organics in carbonaceous chondrites. We recently conducted a synchrotron micro-CT experiment on a powdered sample of the Murchison CM2 carbonaceous chondrite exposed to a monochromatic high energy (approximately 48 kiloelectronvolts) total X-ray radiation dose of approximately 1 kilogray (kGy) using the Advanced Photon Source beamline 13-BMD (13-Bending Magnet-D Beamline) at Argonne National Laboratory and found that there were no detectable changes in the amino acid abundances or enantiomeric compositions in the chondrite after exposure relative to a Murchison control sample that was not exposed. However, lower energy bremsstrahlung X-rays could interact more with amino acids and other lower molecular weight amines in meteorites. To test for this possibility, three separate micro-CT imaging experiments of the Murchison meteorite using the GE Phoenix v/tome/x s 240 kilovolt microfocus high resolution tungsten target X-ray tube instrument at the American Museum of Natural History (AMNH) were conducted and the amino acid abundances and enantiomeric compositions were determined. We also investigated the abundances of the C1-C5 amines in Murchison which were not analyzed in the first study.

Health assessment for Mather Air Force Base, California, Region 9. CERCLIS No. CA8570024143. Preliminary report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

Mather Air Force Base (MAFB), California is east of Sacramento, California. The Air Command and Warning site is the only site within the Base currently on the National Priorities List. Ground water was the only medium sampled; it was found to be contaminated with TCE (0.9 to 22.0 micro g/L), tetrachloroethylene (0.6 to 3.6 micro g/L), vinyl chloride (0.7 to 9.9 micro g/L), dichloroethane (2.5 micro g/L), and 1,4-dichlorobenzene (3.3 micro g/L). The health threats posed by contaminants attributable to MAFB have not been evaluated. Ground water and sediment contamination on the base have been confirmed. The site is ofmore » potential health concern because of the potential risk to human health resulting from possible exposure to hazardous substances at concentrations that may result in adverse health effects.« less

MicroRNAs: New Players in Anesthetic-Induced Developmental Neurotoxicity

PubMed Central

Twaroski, Danielle; Bosnjak, Zeljko J.; Bai, Xiaowen

2015-01-01

Growing evidence demonstrates that prolonged exposure to general anesthetics during brain development induces widespread neuronal cell death followed by long-term memory and learning disabilities in animal models. These studies have raised serious concerns about the safety of anesthetic use in pregnant women and young children. However, the underlying mechanisms of anesthetic-induced neurotoxicity are complex and are not well understood. MicroRNAs are endogenous, small, non-coding RNAs that have been implicated to play important roles in many different disease processes by negatively regulating target gene expression. A possible role for microRNAs in anesthetic-induced developmental neurotoxicity has recently been identified, suggesting that microRNA-based signaling might be a novel target for preventing the neurotoxicity. Here we provide an overview of anesthetic-induced developmental neurotoxicity and focus on the role of microRNAs in the neurotoxicity observed in both human stem cell-derived neuron and animal models. Aberrant expression of some microRNAs has been shown to be involved in anesthetic-induced developmental neurotoxicity, revealing the potential of microRNAs as therapeutic or preventive targets against the toxicity. PMID:26146587

Micro Dot Patterning on the Light Guide Panel Using Powder Blasting.

PubMed

Jang, Ho Su; Cho, Myeong Woo; Park, Dong Sam

2008-02-08

This study is to develop a micromachining technology for a light guidepanel(LGP) mold, whereby micro dot patterns are formed on a LGP surface by a singleinjection process instead of existing screen printing processes. The micro powder blastingtechnique is applied to form micro dot patterns on the LGP mold surface. The optimalconditions for masking, laminating, exposure, and developing processes to form the microdot patterns are first experimentally investigated. A LGP mold with masked micro patternsis then machined using the micro powder blasting method and the machinability of themicro dot patterns is verified. A prototype LGP is test- injected using the developed LGPmold and a shape analysis of the patterns and performance testing of the injected LGP arecarried out. As an additional approach, matte finishing, a special surface treatment method,is applied to the mold surface to improve the light diffusion characteristics, uniformity andbrightness of the LGP. The results of this study show that the applied powder blastingmethod can be successfully used to manufacture LGPs with micro patterns by just singleinjection using the developed mold and thereby replace existing screen printing methods.

Long-term (6-wk) hindlimb suspension inhibits spermatogenesis in adult male rats

NASA Technical Reports Server (NTRS)

Tash, Joseph S.; Johnson, Donald C.; Enders, George C.

2002-01-01

The International Space Station will allow extended habitation in space and long-term exposure to microgravity (microG). A concern is the impact of long-term microG exposure on the ability of species to reproduce. The model often used to simulate microG is rat hindlimb suspension (HLS), where the hindlimbs are elevated above the cage floor with a tail harness. Experiments described here are the first to examine the effect of long-term HLS on testicular function in adult male rats. Free-roaming (controls), animals with only the tail harnessed but hindlimbs in contact with the cage floor (TO), and HLS animals were tested for 6 wk. Cryptorchidism was prevented in TO and HLS animals by partial constriction of the inguinal canal with sutures. All parameters were compared at the end of the 6-wk experiment. Testicular weights and spermatogenesis were significantly reduced by HLS, such that no spermatogenic cells beyond round spermatids were present and epididymides were devoid of mature sperm. In many tubules, loss of all germ cells, except a few spermatogonia, resulting in histopathology similar to the Sertoli cell, was observed. Spermatogenesis appeared unaffected in control and TO animals. Sertoli and Leydig cell appearance, testosterone, luteinizing hormone, and follicle-stimulating hormone levels, and epididymal and seminal vesicle weight were unchanged by HLS. Cortisone was not elevated by HLS; thus stress may not be a factor. These results demonstrate that spermatogenesis is severely inhibited by long-term HLS, whereas testicular androgen production is not. These results have significant implications regarding serious effects of long-term exposure to microG on the reproductive capability of scrotal mammals, including humans.

Survey of electromagnetic field exposure in bedrooms of residences in lower Austria.

PubMed

Tomitsch, Johannes; Dechant, Engelbert; Frank, Wilhelm

2010-04-01

Previous investigations of exposure to electric, magnetic, or electromagnetic fields (EMF) in households were either about electricity supply EMFs or radio frequency EMFs (RF-EMFs). We report results from spot measurements at the bedside that comprise electrostatic fields, extremely low-frequency electric fields (ELF-EFs), extremely low-frequency magnetic fields (ELF-MFs), and RF-EMFs. Measurements were taken in 226 households throughout Lower Austria. In addition, effects of simple reduction measures (e.g., removal of clock radios or increasing their distance from the bed, turning off Digital Enhanced Cordless Telecommunication (DECT) telephone base stations) were assessed. All measurements were well below International Commission on Non-Ionizing Radiation Protection (ICNIRP) guideline levels. Average night-time ELF-MFs (long-term measurement from 10 pm to 6 am, geometric mean over households) above 100 nT were obtained in 2.3%, and RF-EMFs above 1000 microW/m(2) in 7.1% of households. Highest ELF-EFs were primarily due to lamps beside the bed (max = 166 V/m), and highest ELF-MFs because of transformers of devices (max = 1030 nT) or high current of power lines (max = 380 nT). The highest values of RF-EMFs were caused by DECT telephone base stations (max = 28979 microW/m(2)) and mobile phone base stations (max = 4872 microW/m(2)). Simple reduction measures resulted in an average decrease of 23 nT for ELF-MFs, 23 V/m for ELF-EFs, and 246 microW/m(2) for RF-EMFs. A small but statistically significant correlation between ELF-MF exposure and overall RF-EMF levels of R = 0.16 (P = 0.008) was computed that was independent of type (flat, single family) and location (urban, rural) of houses. (c) 2009 Wiley-Liss, Inc.

TU-F-CAMPUS-I-05: Investigation of An EMCCD Detector with Variable Gain in a Micro-CT System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krishnakumar, S Bysani; Ionita, C; Rudin, S

Purpose: To investigate the performance of a newly built Electron Multiplying Charged Coupled Device (EMCCD) based Micro-CT system, with variable detector gain, using a phantom containing contrast agent of different concentrations. Methods: We built a micro- CT system with an EMCCD having 8 microns pixels and on-chip variable gain. We tested the system using a phantom containing five tubes filled with different iodine contrast solutions (30% to 70%). First, we scanned the phantom using various x-ray exposures values at 40 kVp and constant detector gain. Next, for the same tube currents, the detector gain was increased to maintain the airmore » value of the projection image constant. A standard FDK algorithm was used to reconstruct the data. Performance was analyzed by comparing the signal-to-noise ratio (SNR) measurements for increased gain with those for the low constant gain at each exposure. Results: The high detector gain reconstructed data SNR was always greater than the low gain data SNR for all x-ray settings and for all iodine features. The largest increases were observed for low contrast features, 30% iodine concentration, where the SNR improvement approached 2. Conclusion: One of the first implementations of an EMCCD based micro- CT system was presented and used to image a phantom with various iodine solution concentrations. The analysis of the reconstructed volumes showed a significant improvement of the SNR especially for low contrast features. The unique on-chip gain feature is a substantial benefit allowing the use of the system at very low x-ray exposures per frame.Partial support: NIH grant R01EB002873 and Toshiba Medical Systems Corp. Partial support: NIH grant R01EB002873 and Toshiba Medical Systems Corp.« less

Description of Updates for MCCEM Version 1.2 (February 2001)

EPA Pesticide Factsheets

The EPA Office of Pollution Prevention and Toxics, Economics, Exposure, and Technology Division has developed several exposure assessment tools and models. A description of the models and tools and the definition of exposure are given in separate web page

Evaluation of workers' exposure to methylene diphenyl diisocyanate (MDI) in an automobile manufacturing company, Iran.

PubMed

Kakooei, Hossein; Shahtaheri, Seyed Jamaleddin; Karbasi, Hossein-Ali

2006-01-01

Evaluation of personal inhalation exposure to methylene diphenyl diisocyanate (MDI) among 39 employees, working in the window fixation and window glue processes in an automobile manufacturing company was performed. This study was conducted for both case and control groups. After sampling and sample preparation processes, MDI was determined with a UV-VIS spectrophotometer at 590 nm; the lung function was assessed with a digital spirometer, too. The average concentration of MDI in the window fixation, and window glue workplaces were 34.53 and 27.37 micro g/m3, respectively, which was lower than the threshold limit value (TLV) recommended by the American Conference of Governmental Industrial Hygienists (ACGIH) (51 micro g/m3). Respiratory symptoms in the exposed group were significantly different compared to the unexposed group (p < .05). Lung capacities in the case group were lower than in the control group (p < .05). Therefore, MDI can be easily measured making it possible to evaluate the adverse effects caused by occupational exposure.

MicroRNA Expression Profiling of the Armed Forces Health Surveillance Branch Cohort for Identification of "Enviro-miRs" Associated With Deployment-Based Environmental Exposure.

PubMed

Dalgard, Clifton L; Polston, Keith F; Sukumar, Gauthaman; Mallon, Col Timothy M; Wilkerson, Matthew D; Pollard, Harvey B

2016-08-01

The aim of this study was to identify serum microRNA (miRNA) biomarkers that indicate deployment-associated exposures in service members at military installations with open burn pits. Another objective was to determine detection rates of miRNAs in Department of Defense Serum Repository (DoDSR) samples with a high-throughput methodology. Low-volume serum samples (n = 800) were profiled by miRNA-capture isolation, pre-amplification, and measurement by a quantitative PCR-based OpenArray platform. Normalized quantitative cycle values were used for differential expression analysis between groups. Assay specificity, dynamic range, reproducibility, and detection rates by OpenArray passed target desired specifications. Serum abundant miRNAs were consistently measured in study specimens. Four miRNAs were differentially expressed in the case deployment group subjects. miRNAs are suitable RNA species for biomarker discovery in the DoDSR serum specimens. Serum miRNAs are candidate biomarkers for deployment and environmental exposure in military service members.

Cigarette-Smoke-Induced Dysregulation of MicroRNA Expression and Its Role in Lung Carcinogenesis

PubMed Central

Russ, Rebecca; Slack, Frank J.

2012-01-01

Dysregulation of microRNAs (miRNAs), particularly their downregulation, has been widely shown to be associated with the development of lung cancer. Downregulation of miRNAs leads to the overactivation of their oncogene targets, while upregulation of some miRNAs leads to inhibition of important tumor suppressors. Research has implicated cigarette smoke in miRNA dysregulation, leading to carcinogenesis. Cigarette smoke may lead to genetic or epigenetic damage to miRNAs, many of which map to fragile sites and some of which contain single nucleotide polymorphisms. Cigarette smoke may also cause dysregulation by affecting regulatory mechanisms controlling miRNA expression. Researchers have shown a correlation between smoke-exposure-induced dysregulation of miRNAs and age. Furthermore, dysregulation seems to be associated with intensity and duration of smoke exposure and duration of cessation. Longer exposure at a threshold level is needed for irreversibility of changes in expression. Better understanding of miRNA dysregulation may allow for improved biomonitoring and treatment regimens for lung cancer. PMID:22191027

The microRNAs as potential biomarkers for predicting the onset of aflatoxin exposure in human beings: a review.

PubMed

Valencia-Quintana, Rafael; Sánchez-Alarcón, Juana; Tenorio-Arvide, María G; Deng, Youjun; Montiel-González, José M R; Gómez-Arroyo, Sandra; Villalobos-Pietrini, Rafael; Cortés-Eslava, Josefina; Flores-Márquez, Ana R; Arenas-Huertero, Francisco

2014-01-01

The identification of aflatoxins as human carcinogens has stimulated extensive research efforts, which continue to the present, to assess potential health hazards resulting from contamination of the human food supply and to minimize exposure. The use of biomarkers that are mechanistically supported by toxicological studies will be important tools for identifying stages in the progression of development of the health effects of environmental agents. miRNAs are small non-coding mRNAs that regulate post-transcriptional gene expression. Also, they are molecular markers of cellular responses to various chemical agents. Growing evidence has demonstrated that environmental chemicals can induce changes in miRNA expression. miRNAs are good biomarkers because they are well defined, chemically uniform, restricted to a manageable number of species, and stable in cells and in the circulation. miRNAs have been used as serological markers of HCC and other tumors. The expression patterns of different miRNAs can distinguish among HCC-hepatitis viruses related, HCC cirrhosis-derivate, and HCC unrelated to either of them. The main objective of this review is to find unreported miRNAs in HCC related to other causes, so that they can be used as specific molecular biomarkers in populations exposed to aflatoxins and as early markers of exposure, damage/presence of HCC. Until today specific miRNAs as markers for aflatoxins-exposure and their reliability are currently lacking. Based on their elucidated mechanisms of action, potential miRNAs that could serve as possible markers of HCC by exposure to aflatoxins are miR-27a, miR-27b, miR-122, miR-148, miR-155, miR-192, miR-214, miR-221, miR-429, and miR-500. Future validation for all of these miRNAs will be needed to assess their prognostic significance and confirm their relationship with the induction of HCC due to aflatoxin exposure.

Mathematical Micro-Identities: Moment-to-Moment Positioning and Learning in a Fourth-Grade Classroom

ERIC Educational Resources Information Center

Wood, Marcy B.

2013-01-01

Identity is an important tool for understanding students' participation in mathematics lessons. Researchers usually examine identity at a macro-scale: across typical classroom activity and in students' self-reports. However, learning occurs on a micro-scale: in moments during a lesson. To capture identity in these moments, I used positioning…

Can Students Identify the Relevant Information to Solve a Problem?

ERIC Educational Resources Information Center

Zhang, Lishan; Yu, Shengquan; Li, Baoping; Wang, Jing

2017-01-01

Solving non-routine problems is one of the most important skills for the 21st century. Traditional paper-pencil tests cannot assess this type of skill well because of their lack of interactivity and inability to capture procedural data. Tools such as MicroDYN and MicroFIN have proved to be trustworthy in assessing complex problem-solving…

MicroRNAs associated with exercise and diet: a systematic review.

PubMed

Flowers, Elena; Won, Gloria Y; Fukuoka, Yoshimi

2015-01-01

MicroRNAs are posttranscriptional regulators of gene expression. MicroRNAs reflect individual biologic adaptation to exposures in the environment. As such, measurement of circulating microRNAs presents an opportunity to evaluate biologic changes associated with behavioral interventions (i.e., exercise, diet) for weight loss. The aim of this study was to perform a systematic review of the literature to summarize what is known about circulating microRNAs associated with exercise, diet, and weight loss. We performed a systematic review of three scientific databases. We included studies reporting on circulating microRNAs associated with exercise, diet, and weight loss in humans. Of 1,219 studies identified in our comprehensive database search, 14 were selected for inclusion. Twelve reported on microRNAs associated with exercise, and two reported on microRNAs associated with diet and weight loss. The majority of studies used a quasiexperimental, cross-sectional design. There were numerous differences in the type and intensity of exercise and dietary interventions, the biologic source of microRNAs, and the methodological approaches used quantitate microRNAs. Data from several studies support an association between circulating microRNAs and exercise. The evidence for an association between circulating microRNAs and diet is weaker because of a small number of studies. Additional research is needed to validate previous observations using methodologically rigorous approaches to microRNA quantitation to determine the specific circulating microRNA signatures associated with behavioral approaches to weight loss. Future directions include longitudinal studies to determine if circulating microRNAs are predictive of response to behavioral interventions. Copyright © 2015 the American Physiological Society.

Butyltin exposure causes a rapid decrease in cyclic AMP levels in human lymphocytes.

PubMed

Whalen, M M; Loganathan, B G

2001-03-15

Natural killer (NK) cells are a subset of lymphocytes that are capable of killing tumor cells, virally infected cells, and antibody-coated cells. Butyltins (BTs) are used in a variety of consumer products and industrial applications. Tributyltin (TBT) is found in dairy products, meat, and fish. Dibutyltin (DBT) is found in plastic products, beverages stored in PVC pipes during manufacturing, and poultry products. BTs appear to increase the risk of cancer and viral infections in exposed individuals. This increased risk may be due in part to the inhibitory effect of these compounds on the cytotoxic function of NK cells. A 24-h exposure of NK cells to 200 nM TBT or 1.5 microM DBT decreased the cytotoxic function of NK cells by greater than 90%. Higher concentrations of TBT and DBT decreased the cytotoxic function of NK cells (by greater than 90%) after only a 1-h exposure. A 24-h exposure to either TBT or DBT decreased intracellular ATP levels by about 30%. However, as much as a 1-h exposure to either 300 nM TBT or 10 microM DBT caused no significant decrease in ATP levels. Thus, a decrease in ATP levels is a longer-term consequence of BT exposure. Intracellular levels of cAMP are decreased by as much as 80% within 5 min of exposure to either TBT or DBT. This rapid decline in cAMP levels in NK cells may be a consequence of BT exposure that is related to the rapid decrease in the cytotoxic function of NK cells. Copyright 2001 Academic Press.

Modeling the direct sun component in buildings using matrix algebraic approaches: Methods and validation

DOE PAGES

Lee, Eleanor S.; Geisler-Moroder, David; Ward, Gregory

2017-12-23

Simulation tools that enable annual energy performance analysis of optically-complex fenestration systems have been widely adopted by the building industry for use in building design, code development, and the development of rating and certification programs for commercially-available shading and daylighting products. The tools rely on a three-phase matrix operation to compute solar heat gains, using as input low-resolution bidirectional scattering distribution function (BSDF) data (10–15° angular resolution; BSDF data define the angle-dependent behavior of light-scattering materials and systems). Measurement standards and product libraries for BSDF data are undergoing development to support solar heat gain calculations. Simulation of other metrics suchmore » as discomfort glare, annual solar exposure, and potentially thermal discomfort, however, require algorithms and BSDF input data that more accurately model the spatial distribution of transmitted and reflected irradiance or illuminance from the sun (0.5° resolution). This study describes such algorithms and input data, then validates the tools (i.e., an interpolation tool for measured BSDF data and the five-phase method) through comparisons with ray-tracing simulations and field monitored data from a full-scale testbed. Simulations of daylight-redirecting films, a micro-louvered screen, and venetian blinds using variable resolution, tensor tree BSDF input data derived from interpolated scanning goniophotometer measurements were shown to agree with field monitored data to within 20% for greater than 75% of the measurement period for illuminance-based performance parameters. The three-phase method delivered significantly less accurate results. We discuss the ramifications of these findings on industry and provide recommendations to increase end user awareness of the current limitations of existing software tools and BSDF product libraries.« less

Modeling the direct sun component in buildings using matrix algebraic approaches: Methods and validation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Eleanor S.; Geisler-Moroder, David; Ward, Gregory

Simulation tools that enable annual energy performance analysis of optically-complex fenestration systems have been widely adopted by the building industry for use in building design, code development, and the development of rating and certification programs for commercially-available shading and daylighting products. The tools rely on a three-phase matrix operation to compute solar heat gains, using as input low-resolution bidirectional scattering distribution function (BSDF) data (10–15° angular resolution; BSDF data define the angle-dependent behavior of light-scattering materials and systems). Measurement standards and product libraries for BSDF data are undergoing development to support solar heat gain calculations. Simulation of other metrics suchmore » as discomfort glare, annual solar exposure, and potentially thermal discomfort, however, require algorithms and BSDF input data that more accurately model the spatial distribution of transmitted and reflected irradiance or illuminance from the sun (0.5° resolution). This study describes such algorithms and input data, then validates the tools (i.e., an interpolation tool for measured BSDF data and the five-phase method) through comparisons with ray-tracing simulations and field monitored data from a full-scale testbed. Simulations of daylight-redirecting films, a micro-louvered screen, and venetian blinds using variable resolution, tensor tree BSDF input data derived from interpolated scanning goniophotometer measurements were shown to agree with field monitored data to within 20% for greater than 75% of the measurement period for illuminance-based performance parameters. The three-phase method delivered significantly less accurate results. We discuss the ramifications of these findings on industry and provide recommendations to increase end user awareness of the current limitations of existing software tools and BSDF product libraries.« less

Quantitative measures of air-gun pulses recorded on sperm whales (Physeter macrocephalus) using acoustic tags during controlled exposure experiments.

PubMed

Madsen, P T; Johnson, M; Miller, P J O; Aguilar Soto, N; Lynch, J; Tyack, P

2006-10-01

The widespread use of powerful, low-frequency air-gun pulses for seismic seabed exploration has raised concern about their potential negative effects on marine wildlife. Here, we quantify the sound exposure levels recorded on acoustic tags attached to eight sperm whales at ranges between 1.4 and 12.6 km from controlled air-gun array sources operated in the Gulf of Mexico. Due to multipath propagation, the animals were exposed to multiple sound pulses during each firing of the array with received levels of analyzed pulses falling between 131-167 dB re. 1 microPa (pp) [111-147 dB re. 1 microPa (rms) and 100-135 dB re. 1 microPa2 s] after compensation for hearing sensitivity using the M-weighting. Received levels varied widely with range and depth of the exposed animal precluding reliable estimation of exposure zones based on simple geometric spreading laws. When whales were close to the surface, the first arrivals of air-gun pulses contained most energy between 0.3 and 3 kHz, a frequency range well beyond the normal frequencies of interest in seismic exploration. Therefore air-gun arrays can generate significant sound energy at frequencies many octaves higher than the frequencies of interest for seismic exploration, which increases concern of the potential impact on odontocetes with poor low frequency hearing.

Advancing Exposure Characterization for Chemical Evaluation and Risk Assessment

EPA Science Inventory

A new generation of scientific tools has emerged to rapidly measure signals from cells, tissues, and organisms following exposure to chemicals. High-visibility efforts to apply these tools for efficient toxicity testing raise important research questions in exposure science. As v...

EPA EcoBox Tools by Receptors - Endangered, Threatened or Other Species of Concern

EPA Pesticide Factsheets

Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Microfabricated X-Ray Optics Technology Development for the Constellation-X Mission

NASA Technical Reports Server (NTRS)

Schattenburg, Mark L.

2003-01-01

During the period of this Cooperative Agreement, MIT developed advanced methods for applying silicon micro-stuctures for the precision assembly of foil x-ray optics in support of the Constellution-X Spectroscopy X-ray Telescope (SXT) development effort at Goddard Space Flight Center (GSFC). MIT developed improved methods for fabricating and characterizing the precision silicon micro-combs. MIT also developed and characterized assembly tools and several types of metrology tools in order to characterize and reduce the errors associated with precision assembly of foil optics. Results of this effort were published and presented to the scientific community and the GSFC SXT team.

Optimizing laser beam profiles using micro-lens arrays for efficient material processing: applications to solar cells

NASA Astrophysics Data System (ADS)

Hauschild, Dirk; Homburg, Oliver; Mitra, Thomas; Ivanenko, Mikhail; Jarczynski, Manfred; Meinschien, Jens; Bayer, Andreas; Lissotschenko, Vitalij

2009-02-01

High power laser sources are used in various production tools for microelectronic products and solar cells, including the applications annealing, lithography, edge isolation as well as dicing and patterning. Besides the right choice of the laser source suitable high performance optics for generating the appropriate beam profile and intensity distribution are of high importance for the right processing speed, quality and yield. For industrial applications equally important is an adequate understanding of the physics of the light-matter interaction behind the process. In advance simulations of the tool performance can minimize technical and financial risk as well as lead times for prototyping and introduction into series production. LIMO has developed its own software founded on the Maxwell equations taking into account all important physical aspects of the laser based process: the light source, the beam shaping optical system and the light-matter interaction. Based on this knowledge together with a unique free-form micro-lens array production technology and patented micro-optics beam shaping designs a number of novel solar cell production tool sub-systems have been built. The basic functionalities, design principles and performance results are presented with a special emphasis on resilience, cost reduction and process reliability.

Leveraging model-based study designs and serial micro-sampling techniques to understand the oral pharmacokinetics of the potent LTB4 inhibitor, CP-105696, for mouse pharmacology studies.

PubMed

Spilker, Mary E; Chung, Heekyung; Visswanathan, Ravi; Bagrodia, Shubha; Gernhardt, Steven; Fantin, Valeria R; Ellies, Lesley G

2017-07-01

1. Leukotriene B4 (LTB4) is a proinflammatory mediator important in the progression of a number of inflammatory diseases. Preclinical models can explore the role of LTB4 in pathophysiology using tool compounds, such as CP-105696, that modulate its activity. To support preclinical pharmacology studies, micro-sampling techniques and mathematical modeling were used to determine the pharmacokinetics of CP-105696 in mice within the context of systemic inflammation induced by a high-fat diet (HFD). 2. Following oral administration of doses > 35 mg/kg, CP-105696 kinetics can be described by a one-compartment model with first order absorption. The compound's half-life is 44-62 h with an apparent volume of distribution of 0.51-0.72 L/kg. Exposures in animals fed an HFD are within 2-fold of those fed a normal chow diet. Daily dosing at 100 mg/kg was not tolerated and resulted in a >20% weight loss in the mice. 3. CP-105696's long half-life has the potential to support a twice weekly dosing schedule. Given that most chronic inflammatory diseases will require long-term therapies, these results are useful in determining the optimal dosing schedules for preclinical studies using CP-105696.

Tooth enamel surface micro-hardness with dual species Streptococcus biofilm after exposure to Java turmeric (Curcuma xanthorrhiza Roxb.) extract

NASA Astrophysics Data System (ADS)

Isjwara, F. R. G.; Hasanah, S. N.; Utami, Sri; Suniarti, D. F.

2017-08-01

Streptococcus biofilm on tooth surfaces can decrease mouth environment pH, thus causing enamel demineralization that can lead to dental caries. Java Turmeric extract has excellent antibacterial effects and can maintain S. mutans biofilm pH at neutral levels for 4 hours. To analyze the effect of Java Turmeric extract on tooth enamel micro-hardness, the Java Turmeric extract was added on enamel tooth samples with Streptococcus dual species biofilm (S. sanguinis and S. mutans). The micro-hardness of enamel was measured by Knoop Hardness Tester. Results showed that Curcuma xanthorrhiza Roxb. could not maintain tooth enamel surface micro-hardness. It is concluded that Java Turmeric extract ethanol could not inhibit the hardness of enamel with Streptococcus dual species biofilm.

A micromachined carbon nanotube film cantilever-based energy cell

NASA Astrophysics Data System (ADS)

Gong, Zhongcheng; He, Yuan; Tseng, Yi-Hsuan; O'Neal, Chad; Que, Long

2012-08-01

This paper reports a new type of energy cell based on micromachined carbon nanotube film (CNF)-lead zirconate titanate cantilevers that is fabricated on silicon substrates. Measurements found that this type of micro-energy cell generates both AC voltages due to the self-reciprocation of the microcantilevers and DC voltages due to the thermoelectric effect upon exposure to light and thermal radiation, resulting from the unique optical and thermal properties of the CNF. Typically the measured power density of the micro-energy cell can be from 4 to 300 μW cm-2 when it is exposed to sunlight under different operational conditions. It is anticipated that hundreds of integrated micro-energy cells can generate power in the range of milliwatts, paving the way for the construction of self-powered micro- or nanosystems.

A framework for optimizing micro-CT in dual-modality micro-CT/XFCT small-animal imaging system

NASA Astrophysics Data System (ADS)

Vedantham, Srinivasan; Shrestha, Suman; Karellas, Andrew; Cho, Sang Hyun

2017-09-01

Dual-modality Computed Tomography (CT)/X-ray Fluorescence Computed Tomography (XFCT) can be a valuable tool for imaging and quantifying the organ and tissue distribution of small concentrations of high atomic number materials in small-animal system. In this work, the framework for optimizing the micro-CT imaging system component of the dual-modality system is described, either when the micro-CT images are concurrently acquired with XFCT and using the x-ray spectral conditions for XFCT, or when the micro-CT images are acquired sequentially and independently of XFCT. This framework utilizes the cascaded systems analysis for task-specific determination of the detectability index using numerical observer models at a given radiation dose, where the radiation dose is determined using Monte Carlo simulations.

Micro- and nanodevices integrated with biomolecular probes

PubMed Central

Alapan, Yunus; Icoz, Kutay; Gurkan, Umut A.

2016-01-01

Understanding how biomolecules, proteins and cells interact with their surroundings and other biological entities has become the fundamental design criterion for most biomedical micro- and nanodevices. Advances in biology, medicine, and nanofabrication technologies complement each other and allow us to engineer new tools based on biomolecules utilized as probes. Engineered micro/nanosystems and biomolecules in nature have remarkably robust compatibility in terms of function, size, and physical properties. This article presents the state of the art in micro- and nanoscale devices designed and fabricated with biomolecular probes as their vital constituents. General design and fabrication concepts are presented and three major platform technologies are highlighted: microcantilevers, micro/nanopillars, and microfluidics. Overview of each technology, typical fabrication details, and application areas are presented by emphasizing significant achievements, current challenges, and future opportunities. PMID:26363089

Thermal modeling and analysis of thin-walled structures in micro milling

NASA Astrophysics Data System (ADS)

Zhang, J. F.; Ma, Y. H.; Feng, C.; Tang, W.; Wang, S.

2017-11-01

The numerical analytical model has been developed to predict the thermal effect with respect to thin walled structures by micro-milling. In order to investigate the temperature distribution around micro-edge of cutter, it is necessary to considering the friction power, the shearing power, the shear area between the tool micro-edge and materials. Due to the micro-cutting area is more difficult to be measured accurately, the minimum chip thickness as one of critical factors is also introduced. Finite element-based simulation was employed by the Advantedge, which was determined from the machining of Ti-6Al-4V over a range of the uncut chip thicknesses. Results from the proposed model have been successfully accounted for the effects of thermal softening for material.

Light-Driven Nano-oscillators for Label-Free Single-Molecule Monitoring of MicroRNA.

PubMed

Chen, Zixuan; Peng, Yujiao; Cao, Yue; Wang, Hui; Zhang, Jian-Rong; Chen, Hong-Yuan; Zhu, Jun-Jie

2018-06-13

Here, we present a mapping tool based on individual light-driven nano-oscillators for label-free single-molecule monitoring of microRNA. This design uses microRNA as a single-molecule damper for nano-oscillators by forming a rigid dual-strand structure in the gap between nano-oscillators and the immobilized surface. The ultrasensitive detection is attributed to comparable dimensions of the gap and microRNA. A developed surface plasmon-coupled scattering imaging technology enables us to directly measure the real-time gap distance vibration of multiple nano-oscillators with high accuracy and fast dynamics. High-level and low-level states of the oscillation amplitude indicate melting and hybridization statuses of microRNA. Lifetimes of two states reveal that the hybridization rate of microRNA is determined by the three-dimensional diffusion. This imaging technique contributes application potentials in a single-molecule detection and nanomechanics study.

Building a bone μCT images atlas for micro-architecture recognition

NASA Astrophysics Data System (ADS)

Freuchet, E.; Recur, B.; Guédon, Jp.; Kingston, A.; Autrusseau, F.; Amouriq, Y.

2015-03-01

Trabecular bone and its micro-architecture are of prime importance for health. Changes of bone micro-architecture are linked to different pathological situations like osteoporosis and begin now to be understood. In a previous paper, we started to investigate the relationships between bone and vessels and we also proposed to build a Bone Atlas. This study describes how to proceed for the elaboration and use of such an atlas. Here, we restricted the Atlas to legs (tibia, femur) of rats in order to work with well known geometry of the bone micro-architecture. From only 6 acquired bone, 132 trabecular bone volumes were generated using simple mathematical morphology tools. The variety and veracity of the created micro-architecture volumes is presented in this paper. Medical application and final goal would be to determinate bone micro-architecture with some angulated radiographs (3 or 4) and to easily diagnose the bone status (healthy, pathological or healing bone...).

Biocompatibility Assessment of Si-based Nano- and Micro-particles

PubMed Central

Jaganathan, Hamsa; Godin, Biana

2012-01-01

Silicon is one of the most abundant chemical elements found on the Earth. Due to its unique chemical and physical properties, silicon based materials and their oxides (e.g. silica) have been used in several industries such as building and construction, electronics, food industry, consumer products and biomedical engineering/medicine. This review summarizes studies on effects of silicon and silica nano- and micro-particles on cells and organs following four main exposure routes, namely, intravenous, pulmonary, dermal and oral. Further, possible genotoxic effects of silica based nanoparticles are discussed. The review concludes with an outlook on improving and standardizing biocompatibility assessment for nano- and micro-particles. PMID:22634160

Guidelines for the functional annotation of microRNAs using the Gene Ontology

PubMed Central

D'Eustachio, Peter; Smith, Jennifer R.; Zampetaki, Anna

2016-01-01

MicroRNA regulation of developmental and cellular processes is a relatively new field of study, and the available research data have not been organized to enable its inclusion in pathway and network analysis tools. The association of gene products with terms from the Gene Ontology is an effective method to analyze functional data, but until recently there has been no substantial effort dedicated to applying Gene Ontology terms to microRNAs. Consequently, when performing functional analysis of microRNA data sets, researchers have had to rely instead on the functional annotations associated with the genes encoding microRNA targets. In consultation with experts in the field of microRNA research, we have created comprehensive recommendations for the Gene Ontology curation of microRNAs. This curation manual will enable provision of a high-quality, reliable set of functional annotations for the advancement of microRNA research. Here we describe the key aspects of the work, including development of the Gene Ontology to represent this data, standards for describing the data, and guidelines to support curators making these annotations. The full microRNA curation guidelines are available on the GO Consortium wiki (http://wiki.geneontology.org/index.php/MicroRNA_GO_annotation_manual). PMID:26917558

Introduction to the Community-Focused Exposure and Risk Screening Tool (C-FERST)

EPA Pesticide Factsheets

EPA scientists are working partners to design and test the Community-Focused Exposure and Risk Screening Tool (C-FERST), a community mapping, information access, and assessment tool to help assess risk and assist in decision making with communities

An Upper Bound for Population Exposure Variability (SOT)

EPA Science Inventory

Tools for the rapid assessment of exposure potential are needed in order to put the results of rapidly-applied tools for assessing biological activity, such as ToxCast® and other high throughput methodologies, into a quantitative exposure context. The ExpoCast models (Wambaugh et...

Silk Film Embossing System

NASA Astrophysics Data System (ADS)

Paquette, Mark S.

New tools are often required to facilitate new discoveries and test new methods. Commercial offerings can be prohibitively expensive and difficult to customize. The development of ad-hoc tools provides the most flexibility and provides an opportunity to modify and refine a technology. An embossing system was developed for silk film imprinting and stamping in order to facilitate and add versatility to the efforts involving micro- and nanoscale device manufacturing in biopolymers. This system features temperature controlled embossing surfaces, adjustable embossing pressures, and variable embossing times. The device can also be fitted with interchangeable temperature controlled embossing and stamping tools. The design, development, fabrication, applications, and future improvements are explored for the system. This device may facilitate new discoveries in the realm of biopolymer micro- and nanomanufacturing and may provide a path towards high volume production of silk film based technologies.

Should the Centers for Disease Control and Prevention's childhood lead poisoning intervention level be lowered?

PubMed

Bernard, Susan M

2003-08-01

The US Centers for Disease Control and Prevention (CDC) in 1991 chose 10 micro g/dL as an initial screening level for lead in children's blood. Current data on health risks and intervention options do not support generally lowering that level, but federal lead poisoning prevention efforts can be improved by revising the follow-up testing schedule for infants aged 1 year or less with blood lead levels of 5 micro g/dL or higher; universal education about lead exposure risks; universal administration of improved, locally validated risk-screening questionnaires; enhanced compliance with targeted screening recommendations and federal health program requirements; and development by regulatory agencies of primary prevention criteria that do not use the CDC's intervention level as a target "safe" lead exposure.

Detection biomarkers of lung cancer using mini-GC-PID system integrated with micro GC column and micro pre-concentrator

PubMed Central

2014-01-01

The survival rate of lung cancer can be significantly improved by monitoring biomarkers in exhaled air that indicate diseases in early stage, so it is very important to develop micro analytical systems which can offer a fast, on-site, real-time detecting biomarkers in exhaled air. In this paper, a mini-gas chromatography (GC)-photo-ionization detector (PID) system integrated with a micro GC column and a micro pre-concentrator was developed for forming an inexpensive, fast, and non-invasive diagnostic tool for lung cancer. This system has very strong concentrate ability owing to its integrated micro pre-concentrator, which make the detection of trace components in exhaled air very easy. In addition, the integrated micro GC column can separate complex mixtures, which overcome low resolution and poor anti-interference ability of other instruments. The results indicated that the mini-GC-PID system can effectively separate and detect the biomarkers at parts-per-billion (ppb) level. PMID:25339856

A comparative analysis of high-throughput platforms for validation of a circulating microRNA signature in diabetic retinopathy.

PubMed

Farr, Ryan J; Januszewski, Andrzej S; Joglekar, Mugdha V; Liang, Helena; McAulley, Annie K; Hewitt, Alex W; Thomas, Helen E; Loudovaris, Tom; Kay, Thomas W H; Jenkins, Alicia; Hardikar, Anandwardhan A

2015-06-02

MicroRNAs are now increasingly recognized as biomarkers of disease progression. Several quantitative real-time PCR (qPCR) platforms have been developed to determine the relative levels of microRNAs in biological fluids. We systematically compared the detection of cellular and circulating microRNA using a standard 96-well platform, a high-content microfluidics platform and two ultra-high content platforms. We used extensive analytical tools to compute inter- and intra-run variability and concordance measured using fidelity scoring, coefficient of variation and cluster analysis. We carried out unprejudiced next generation sequencing to identify a microRNA signature for Diabetic Retinopathy (DR) and systematically assessed the validation of this signature on clinical samples using each of the above four qPCR platforms. The results indicate that sensitivity to measure low copy number microRNAs is inversely related to qPCR reaction volume and that the choice of platform for microRNA biomarker validation should be made based on the abundance of miRNAs of interest.

Adhesive micro-line periodicity determines guidance of axonal outgrowth†

PubMed Central

Huang, Yu; Fothergill, Thomas; Lumbard, Derek C.; Dent, Erik W.; Williams, Justin C.

2014-01-01

Adhesive micro-lines of various sub-cellular geometries were created using a non-traditional micro stamping technique. This technique employed the use of commercially available diffraction gratings as the molds for the micro stamps, a method which is quick and inexpensive, and which could easily be adopted as a patterning tool in a variety of research efforts. The atypical saw-tooth profile of the micro stamps enabled a unique degree of control and flexibility over patterned line and gap widths. Cortical neurons cultured on patterned poly-lysine micro-lines on PDMS exhibit a startling transition in axonal guidance: From the expected parallel guidance to an unexpected perpendicular guidance that becomes dominant as patterned lines and gaps become sufficiently narrow. This transition is most obvious when the lines are narrow relative to gaps, while the periodicity of the pattern is reduced. Axons growing perpendicular to micro-lines exhibited ‘vinculated’ growth, a unique morphological phenotype consisting of periodic orthogonal extensions along the axon. PMID:23250489

An Accurate and Computationally Efficient Model for Membrane-Type Circular-Symmetric Micro-Hotplates

PubMed Central

Khan, Usman; Falconi, Christian

2014-01-01

Ideally, the design of high-performance micro-hotplates would require a large number of simulations because of the existence of many important design parameters as well as the possibly crucial effects of both spread and drift. However, the computational cost of FEM simulations, which are the only available tool for accurately predicting the temperature in micro-hotplates, is very high. As a result, micro-hotplate designers generally have no effective simulation-tools for the optimization. In order to circumvent these issues, here, we propose a model for practical circular-symmetric micro-hot-plates which takes advantage of modified Bessel functions, computationally efficient matrix-approach for considering the relevant boundary conditions, Taylor linearization for modeling the Joule heating and radiation losses, and external-region-segmentation strategy in order to accurately take into account radiation losses in the entire micro-hotplate. The proposed model is almost as accurate as FEM simulations and two to three orders of magnitude more computationally efficient (e.g., 45 s versus more than 8 h). The residual errors, which are mainly associated to the undesired heating in the electrical contacts, are small (e.g., few degrees Celsius for an 800 °C operating temperature) and, for important analyses, almost constant. Therefore, we also introduce a computationally-easy single-FEM-compensation strategy in order to reduce the residual errors to about 1 °C. As illustrative examples of the power of our approach, we report the systematic investigation of a spread in the membrane thermal conductivity and of combined variations of both ambient and bulk temperatures. Our model enables a much faster characterization of micro-hotplates and, thus, a much more effective optimization prior to fabrication. PMID:24763214

Optical Micromachining

NASA Technical Reports Server (NTRS)

1998-01-01

Under an SBIR (Small Business Innovative Research) with Marshall Space Flight Center, Potomac Photonics, Inc., constructed and demonstrated a unique tool that fills a need in the area of diffractive and refractive micro-optics. It is an integrated computer-aided design and computer-aided micro-machining workstation that will extend the benefits of diffractive and micro-optic technology to optical designers. Applications of diffractive optics include sensors and monitoring equipment, analytical instruments, and fiber optic distribution and communication. The company has been making diffractive elements with the system as a commercial service for the last year.

Biotransformation, genotoxic, and histopathological effects of environmental contaminants in European eel (Anguilla anguilla L.).

PubMed

Pacheco, Mário; Santos, Maria Ana

2002-11-01

A prolonged toxicity study was carried out in young European eel (Anguilla anguilla L.) to evaluate the effects of environmental contaminants, namely, two individual standard compounds, benzo[a]pyrene (BaP) and dehydroabietic acid (DHAA), and a complex mixture, bleached kraft pulp mill effluent (BKPME). Fish were exposed to BaP (0.22, 0.45, and 0.9 microM) and BKPME (3.12%, 6.25%, and 12.5% (v/v)) for 3, 7, and 30 days and to DHAA (0.07, 0.15, and 0.30 microM) for 3, 7, 30, 90, and 180 days. The biomarkers include biotransformation and genotoxicity indicators, such as total ethoxyresorufin O-deethylase (EROD) activity and frequency of erythrocytic nuclear abnormalities (ENAs), respectively. Hematological dynamics was assessed as frequency of immature erythrocytes (IEs). Histopathological examinations were carried out for the highest concentrations and for 30 days and longer exposures. Total EROD increases significantly only after 180 days of DHAA exposure. However, significant ENA induction was generally observed during exposure to all contaminants tested. Nevertheless, some of the ENA results suggest an altered genotoxic response, which may arise either from short-term exposures to the highest contaminant levels or long-term exposures to the lowest contaminant levels. IE frequency decreased significantly after 30 days of exposure to 0.45 microM BaP and 180 days of exposure to the entire DHAA concentration range. Increased density of pigmented macrophage aggregates in 30-day BaP- and BKPME-exposed fish as well as in 90- and 180-day DHAA-exposed fish confirmed histopathological liver alterations. Bile accumulation in hepatocytes after BaP treatment, cytoplasmic vacuolization and cell atrophy following DHAA exposure, as well as liver loss of parenchymal cells in BKPME-exposed fish, were also detected. Dispersed necrosis and focal inflammation were observed in the livers of all treated groups. Fish exposed to DHAA and BKPME showed skin and gill disruption as well as kidney Malpighian corpuscle alterations. All 30-day-treated groups revealed intense spleen hemosiderosis, indicating increased erythrophagia. This splenic effect may be strongly correlated with the observed disappearance of ENAs. Neoplastic lesions were not found. A multibiomarker strategy, which includes EROD, ENA, and IE assays as well as histopathological studies, contributed to a better understanding of the global toxic process.

Technical Note: Estimation of Micro-Watershed Topographic Parameters Using Earth Observatory Tools

EPA Science Inventory

The study set out to analyze the feasibility of using Earth observatory tools to derive elevations to characterize topographic parameters of slope gradient and area useful in predicting erosion and for natural resources engineering education and instruction. Earth obseravtory too...

Optimization of a micro-scale, high throughput process development tool and the demonstration of comparable process performance and product quality with biopharmaceutical manufacturing processes.

PubMed

Evans, Steven T; Stewart, Kevin D; Afdahl, Chris; Patel, Rohan; Newell, Kelcy J

2017-07-14

In this paper, we discuss the optimization and implementation of a high throughput process development (HTPD) tool that utilizes commercially available micro-liter sized column technology for the purification of multiple clinically significant monoclonal antibodies. Chromatographic profiles generated using this optimized tool are shown to overlay with comparable profiles from the conventional bench-scale and clinical manufacturing scale. Further, all product quality attributes measured are comparable across scales for the mAb purifications. In addition to supporting chromatography process development efforts (e.g., optimization screening), comparable product quality results at all scales makes this tool is an appropriate scale model to enable purification and product quality comparisons of HTPD bioreactors conditions. The ability to perform up to 8 chromatography purifications in parallel with reduced material requirements per run creates opportunities for gathering more process knowledge in less time. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Design and acceptability of the Aviation Laser Exposure Self-Assessment (ALESA).

PubMed

Waggel, Stephanie E; Hutchison, Ewan J

2013-03-01

There is an increase in reports of aircraft exposed to lasers directed from the ground. Approximately 2300 cases were reported to the United Kingdom Civil Aviation Authority (UK CAA) in 2011. While the likelihood of injuries directly resulting from such exposure is currently low, this may increase with the increasing power of lasers. A project was undertaken to develop a rapid self-assessment tool that would assist pilots in determining whether permanent injury has occurred after eye exposure to a laser and whether professional assessment should be sought. Laser incidents reported to the UK CAA were analyzed. With the aid of expert advice, the Aviation Laser Exposure Self-Assessment (ALESA) tool was produced using key aspects of illumination needed to determine the risk of harm. There were 25 pilots and flight crewmembers who have experienced aviation laser exposure who were given the tool and their response was assessed with a questionnaire. There was a favorable response to five of the six measured aspects of the ALESA. The ALESA is considered a useful tool for pilots following laser exposure during flight. The UK CAA is making the tool available through its website.

Exploiting microRNA Specificity and Selectivity: Paving a Sustainable Path Towards Precision Medicine.

PubMed

Santulli, Gaetano

2015-01-01

In his State of the Union address before both chambers of the US Congress, President Barack Obama called for increased investment in US infrastructure and research and announced the launch of a new Precision Medicine Initiative, aiming to accelerate biomedical discovery. Due to their well-established selectivity and specificity, microRNAs can represent a useful tool, both in diagnosis and therapy, in forging the path towards the achievement of precision medicine. This introductory chapter represents a guide for the Reader in examining the functional roles of microRNAs in the most diverse aspects of clinical practice, which will be explored in this third volume of the microRNA trilogy.

Exploiting microRNA Specificity and Selectivity: Paving a Sustainable Path Towards Precision Medicine

PubMed Central

2016-01-01

In his State of the Union address before both chambers of the US Congress, President Barack Obama called for increased investment in US infrastructure and research and announced the launch of a new Precision Medicine Initiative, aiming to accelerate biomedical discovery. Due to their well-established selectivity and specificity, microRNAs can represent a useful tool, both in diagnosis and therapy, in forging the path towards the achievement of precision medicine. This introductory chapter represents a guide for the Reader in examining the functional roles of microRNAs in the most diverse aspects of clinical practice, which will be explored in this third volume of the microRNA trilogy. PMID:26663175

X-Ray Micro-Computed Tomography of Apollo Samples as a Curation Technique Enabling Better Research

NASA Technical Reports Server (NTRS)

Ziegler, R. A.; Almeida, N. V.; Sykes, D.; Smith, C. L.

2014-01-01

X-ray micro-computed tomography (micro-CT) is a technique that has been used to research meteorites for some time and many others], and recently it is becoming a more common tool for the curation of meteorites and Apollo samples. Micro-CT is ideally suited to the characterization of astromaterials in the curation process as it can provide textural and compositional information at a small spatial resolution rapidly, nondestructively, and without compromising the cleanliness of the samples (e.g., samples can be scanned sealed in Teflon bags). This data can then inform scientists and curators when making and processing future sample requests for meteorites and Apollo samples. Here we present some preliminary results on micro-CT scans of four Apollo regolith breccias. Methods: Portions of four Apollo samples were used in this study: 14321, 15205, 15405, and 60639. All samples were 8-10 cm in their longest dimension and approximately equant. These samples were micro-CT scanned on the Nikon HMXST 225 System at the Natural History Museum in London. Scans were made at 205-220 kV, 135-160 microamps beam current, with an effective voxel size of 21-44 microns. Results: Initial examination of the data identify a variety of mineral clasts (including sub-voxel FeNi metal grains) and lithic clasts within the regolith breccias. Textural information within some of the lithic clasts was also discernable. Of particular interest was a large basalt clast (approx.1.3 cc) found within sample 60639, which appears to have a sub-ophitic texture. Additionally, internal void space, e.g., fractures and voids, is readily identifiable. Discussion: It is clear from the preliminary data that micro-CT analyses are able to identify important "new" clasts within the Apollo breccias, and better characterize previously described clasts or igneous samples. For example, the 60639 basalt clast was previously believed to be quite small based on its approx.0.5 sq cm exposure on the surface of the main mass. These scans show the clast to be approx.4.5 g, however (assuming a density of approx.3.5 g/cc). This is large enough for detailed studies including multiple geo-chronometers. This basalt clast is of particular interest as it is the largest Apollo 16 basalt, and it is the only mid-TiO2 basalt in the Apollo sample suite. By identifying the location of interesting clasts or grains within a sample, we will be able to make more informed decisions about where to cut a sample in order to best expose clasts of interest for future study. Moreover, knowing the location of internal defects (e.g., fractures) will allow more precise chipping and extraction of clasts or grains. By combining micro-CT scans with compositional techniques like micro x-ray fluorescence (particularly on sawn slabs), we will be able to provide even more comprehensive information to scientists trying to best select samples that fit their scientific needs.

Monoclonal Antibody Interactions with Micro- and Nanoparticles: Adsorption, Aggregation and Accelerated Stress Studies

PubMed Central

Bee, Jared S.; Chiu, David; Sawicki, Suzanne; Stevenson, Jennifer L.; Chatterjee, Koustuv; Freund, Erwin; Carpenter, John F.; Randolph, Theodore W.

2009-01-01

Therapeutic proteins are exposed to various wetted surfaces that could shed sub-visible particles. In this work we measured the adsorption of a monoclonal antibody (mAb) to various microparticles, characterized the adsorbed mAb secondary structure, and determined the reversibility of adsorption. We also developed and used a front-face fluorescence quenching method to determine that the mAb tertiary structure was near-native when adsorbed to glass, cellulose and silica. Initial adsorption to each of the materials tested was rapid. During incubation studies, exposure to the air-water interface was a significant cause of aggregation but acted independently of the effects of microparticles. Incubations with glass, cellulose, stainless steel or Fe2O3 microparticles gave very different results. Cellulose preferentially adsorbed aggregates from solution. Glass and Fe2O3 adsorbed the mAb but did not cause aggregation. Adsorption to stainless steel microparticles was irreversible, and caused appearance of soluble aggregates upon incubation. The secondary structure of mAb adsorbed to glass and cellulose was near-native. We suggest that the protocol described in this work could be a useful preformulation stress screening tool to determine the sensitivity of a therapeutic protein to exposure to common surfaces encountered during processing and storage. PMID:19492408

Siderophores, the answer for micro to nanosized asbestos fibre related health hazard

NASA Astrophysics Data System (ADS)

Bhattacharya, Shabori; Ledwani, Lalita; John, P. J.

2016-04-01

Recent studies on the potential toxicity of High Aspect Ratio Nanoparticles (HARN) has yet once again reinforced the health hazard imposed by asbestos fibres ranging from nano to micro size. Asbestos a naturally occurring fibrous mineral declared a Group I definite carcinogen by IARC (International Agency for Research on Cancer), a unit of WHO in the year 1987, has been extensively used since World War II to the near past for various commercial products. According to the most recent World Health Organization (WHO) estimates, asbestos-related diseases, resulting from exposure at workplace claims more than 107000 lives every year worldwide. The various types of toxic effects induced by asbestos in humans include - i) inflammation and fibrogenesis of lung, ii) mesothelioma iii) asbestosis and iv) bronchogenic carcinoma. The stability of asbestos in natural environment and its biological aggressiveness is related to their fibrous structure and dimensions. The actual risk associated with the exposure to nanosized asbestos, which is still unknown and escapes most regulations worldwide, has been shown in various toxicity assessment studies conducted on various animal models.In an effort to reduce the size of asbestos and therby its toxicity by limiting its biopersistence, oxalic acid treatment of asbestos coupled to power ultrasound treatment was carried out. The nanosized particles formed were still found to retain their hazardous effect. Similar were the results obtained on strong acid treatment of asbestos as well. A probable solution to the asbestos toxicity problem therefore envisaged was bioremediation. This involved the secretion of iron chelating molecules termed siderophores by microbes, which are of significance due to their ability to form very stable and soluble complexes with iron. Iron in asbestos composition is a major factor responsible for its carcinogenicity, removal or extraction of which would prove to be an effective answer to the worldwide problem. Siderophores are low molecular weight organic compounds with a very high and specific affinity to chelate iron and enhance their diffusion to the microbial cell surface. A number of successful experiments carried out in vitro have shown positive results concerning reduction in asbestos toxicity on chelation of iron by siderophores. The present investigation tends to put forth the aspect of these biomolecules secreted by specific bacteria and fungi as potent tools to fight the micro to nano sized asbestos fibre toxicity.

[Absorbed doses to critical organs from full mouth dental radiography].

PubMed

Zhang, G; Yasuhiko, O; Hidegiko, Y

1999-01-01

A few studies were reported in China on radiological risk of dental radiography. The aim of this study is to evaluate the absorbed doses of patients from the full mouth radiographs, and to find out the contribution from each projection to the total absorbed dose of the organs. Absorbed doses to critical organs were measured from 14-film complete dental radiography. The organs included pituitary, optical lens, parotid glands, submandibular glands, sublingual glands, thyroid, breasts, ovary, testes and the skin in center field of each projection were studied. A-radiation analog dosimetry system (RANDO) phantom with thermoluminescent dosimeters (ILD200) was used for the study. All of the exposure parameters were fixed. The total filtration was 2 mm Al equivalent. The column collaboration was 6 cm in diameter and 20 cm in length. The absorbed doses of organs were measured three times in each projection of the full-mouth series (FMS) exposures. The absorbed dose of lenses in FMS (249 microGy) in present study was much less (10%) than the doses (2,630 microGy) reported in 1976. The doses absorbed of other organs in the present study were thyroid gland (125 microGy), pituitary gland (112 microGy), parotid gland (153 microGy), submandibular gland (629 microGy), sublingual gland (1,900 microGy), and breast gland (12 microGy). The doses of the ovary and testis were to small to further analysis. All of the results show that the radiation risk to patients in intraoral radiograph has been reduced significantly. In the pituitary, half of the dose is from both sides of the maxillary molar projection. For the lenses, the largest contribultions of radiation (60%) come from the ipsilateral molar and premolar projection of maxilla. In parotid gland, up to 57% of the dose is from the contralateral molar, pre-molar and canine of maxilla. It could be derived that about 90% of the absorbed doses could be avoided in FMS if the column collimator is 20 cm long and the filter is 2.0 mm thick. If we use the 10-film complete mouth radiograph instead of the 14-film series, more 20% of the doses would be reduced.

The Correlation between Accounting Systems of Small and Micro Enterprises and Tax Revenue Assessment in Ghana

ERIC Educational Resources Information Center

Nkuah, Joseph Kofi; Frederick, Appiah- Kusi; Asamoah, Kwame

2015-01-01

The purpose of the study was to find out the correlation between accounting systems of Small and Micro Enterprises and tax revenue assessment. The study was be based on descriptive research survey using questionnaires and interviews as main tools to gather both primary and secondary data to establish the correlation between sound financial record…

Condition assessment of timber bridges. 1, Evaluation of a micro-drilling resistance tool

Treesearch

Brian K. Brashaw; Robert J. Vatalaro; James P. Wacker; Robert J. Ross

2005-01-01

The research presented in this report was conducted to evaluate the accuracy and reliability of a commercially available micro-drilling resistance device, the IML RESI F300-S (Instrument Mechanic Labor, Inc., Kennesaw, Georgia), in locating deteriorated areas in timber bridge members. The device records drilling resistance as a function of drilling depth, which allows...

The genomic response of a human uterine endometrial adenocarcinoma cell line to 17alpha-ethynyl estradiol.

PubMed

Naciff, Jorge M; Khambatta, Zubin S; Thomason, Ryan G; Carr, Gregory J; Tiesman, Jay P; Singleton, David W; Khan, Sohaib A; Daston, George P

2009-01-01

We have determined the gene expression profile induced by 17 alpha-ethynyl estradiol (EE) in Ishikawa cells, a human uterine-derived estrogen-sensitive cell line, at various doses (1 pM, 100 pM, 10 nM, and 1 microM) and time points (8, 24, and 48 h). The transcript profiles were compared between treatment groups and controls (vehicle-treated) using high-density oligonucleotide arrays to determine the expression level of approximately 38,500 human genes. By trend analysis, we determined that the expression of 2560 genes was modified by exposure to EE in a dose- and time-dependent manner (p

Zinc and cadmium accumulation in single zebrafish ( Danio rerio) embryos — A total reflection X-ray fluorescence spectrometry application

NASA Astrophysics Data System (ADS)

Mages, Margarete; Bandow, Nicole; Küster, Eberhard; Brack, Werner; von Tümpling, Wolf

2008-12-01

Trace metals such as Cadmium (Cd) and Zinc (Zn) are known to exhibit adverse effects on many aquatic organisms including early life stages of fish. In contact with contaminated sediment, fish eggs and embryos may be exposed to metals via the water phase as well as via direct contact with contaminated particles. This may result in body burdens that are difficult to predict and may vary according to individual micro scale exposure conditions. The highly sensitive total reflection X-ray fluorescence spectrometry (TXRF) may provide a tool to analyse individual embryos for internal contaminant concentrations and thus helps to develop a better understanding of dose-response relationships. To test this hypothesis, embryos of Danio rerio were exposed to Cd and Zn spiked sediment in different treatments applying an ion exchange resin for modification of bioavailable concentrations. The TXRF analysis indicated individual embryos with dramatically enhanced exposure compared to other individuals despite uniform exposure conditions on a macro scale. Ion exchanger reduced embryo Zn concentrations to values close to control value with a comparably low standard deviation. Cadmium concentrations in embryos were in the range of 4000 to 7000 µg/g with a median of 5740 µg/g. A commercial ion exchanger reduced individual body burdens by a factor 50 to 100. Individual peak body burdens of up to 3160 µg/g were accompanied by reduced weight of the fish eggs due to early death i.e. coagulation. The investigation of exposure and effects on an individual-based scale may significantly help to reduce uncertainty and inconsistencies occurring in conventional analysis of pooled fish embryo samples.

Fabrication of micro metallic valve and pump

NASA Astrophysics Data System (ADS)

Yang, Ming; Kabasawa, Yasunari; Ito, Kuniyoshi

2010-03-01

Fabrication of micro devices by using micro metal forming was proposed by the authors. We developed a desktop servo-press machine with precise tooling system. Precise press forming processes including micro forging and micro joining has been carried out in a progressive die. In this study, micro metallic valve and pump were fabricated by using the precise press forming. The components are made of sheet metals, and assembled in to a unit in the progressive die. A micro check-valve with a diameter of 3mm and a length of 3.2mm was fabricated, and the property of flow resistance was evaluated. The results show that the check valve has high property of leakage proof. Since the valve is a unit parts with dimensions of several millimeters, it has advantage to be adapted to various pump design. Here, two kinds of micro pumps with the check-valves were fabricated. One is diaphragm pump actuated by vibration of the diaphragm, and another is tube-shaped pump actuated by resonation. The flow quantities of the pumps were evaluated and the results show that both of the pumps have high pumping performance.

MicroScope-an integrated resource for community expertise of gene functions and comparative analysis of microbial genomic and metabolic data.

PubMed

Médigue, Claudine; Calteau, Alexandra; Cruveiller, Stéphane; Gachet, Mathieu; Gautreau, Guillaume; Josso, Adrien; Lajus, Aurélie; Langlois, Jordan; Pereira, Hugo; Planel, Rémi; Roche, David; Rollin, Johan; Rouy, Zoe; Vallenet, David

2017-09-12

The overwhelming list of new bacterial genomes becoming available on a daily basis makes accurate genome annotation an essential step that ultimately determines the relevance of thousands of genomes stored in public databanks. The MicroScope platform (http://www.genoscope.cns.fr/agc/microscope) is an integrative resource that supports systematic and efficient revision of microbial genome annotation, data management and comparative analysis. Starting from the results of our syntactic, functional and relational annotation pipelines, MicroScope provides an integrated environment for the expert annotation and comparative analysis of prokaryotic genomes. It combines tools and graphical interfaces to analyze genomes and to perform the manual curation of gene function in a comparative genomics and metabolic context. In this article, we describe the free-of-charge MicroScope services for the annotation and analysis of microbial (meta)genomes, transcriptomic and re-sequencing data. Then, the functionalities of the platform are presented in a way providing practical guidance and help to the nonspecialists in bioinformatics. Newly integrated analysis tools (i.e. prediction of virulence and resistance genes in bacterial genomes) and original method recently developed (the pan-genome graph representation) are also described. Integrated environments such as MicroScope clearly contribute, through the user community, to help maintaining accurate resources. © The Author 2017. Published by Oxford University Press.

Automatic alternative phase-shift mask CAD layout tool for gate shrinkage of embedded DRAM in logic below 0.18 μm

NASA Astrophysics Data System (ADS)

Ohnuma, Hidetoshi; Kawahira, Hiroichi

1998-09-01

An automatic alternative phase shift mask (PSM) pattern layout tool has been newly developed. This tool is dedicated for embedded DRAM in logic device to shrink gate line width with improving line width controllability in lithography process with a design rule below 0.18 micrometers by the KrF excimer laser exposure. The tool can crete Levenson type PSM used being coupled with a binary mask adopting a double exposure method for positive photo resist. By using graphs, this tool automatically creates alternative PSM patterns. Moreover, it does not give any phase conflicts. By adopting it to actual embedded DRAM in logic cells, we have provided 0.16 micrometers gate resist patterns at both random logic and DRAM areas. The patterns were fabricated using two masks with the double exposure method. Gate line width has been well controlled under a practical exposure-focus window.

Characterization of polydimethylsiloxane (PDMS) properties for biomedical micro/nanosystems.

PubMed

Mata, Alvaro; Fleischman, Aaron J; Roy, Shuvo

2005-12-01

Polydimethylsiloxane (PDMS Sylgard 184, Dow Corning Corporation) pre-polymer was combined with increasing amounts of cross-linker (5.7, 10.0, 14.3, 21.4, and 42.9 wt.%) and designated PDMS1, PDMS2, PDMS3, PDMS4, and PDMS5, respectively. These materials were processed by spin coating and subjected to common micro-fabrication, micro-machining, and biomedical processes: chemical immersion, oxygen plasma treatment, sterilization, and exposure to tissue culture media. The PDMS formulations were analyzed by gravimetry, goniometry, tensile testing, nano-indentation, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Spin coating of PDMS was formulation dependent with film thickness ranging from 308 microm on PDMS1 to 171 microm on PDMS5 at 200 revolutions per minute (rpm). Ultimate tensile stress (UTS) increased from 3.9 MPa (PDMS1) to 10.8 MPa (PDMS3), and then decreased down to 4.0 MPa (PDMS5). Autoclave sterilization (AS) increased the storage modulus (sigma) and UTS in all formulations, with the highest increase in UTS exhibited by PDMS5 (218%). PDMS surface hydrophilicity and micro-textures were generally unaffected when exposed to the different chemicals, except for micro-texture changes after immersion in potassium hydroxide and buffered hydrofluoric, nitric, sulfuric, and hydrofluoric acids; and minimal changes in contact angle after immersion in hexane, hydrochloric acid, photoresist developer, and toluene. Oxygen plasma treatment decreased the contact angle of PDMS2 from 109 degrees to 60 degrees. Exposure to tissue culture media resulted in increased PDMS surface element concentrations of nitrogen and oxygen.

Electron-beam-induced topographical, chemical, and structural patterning of amorphous titanium oxide films.

PubMed

Kern, P; Müller, Y; Patscheider, J; Michler, J

2006-11-30

Electrolytically deposited amorphous TiO2 films on steel are remarkably sensitive to electron beam (e-beam) irradiation at moderate energies at 20 keV, resulting in controlled local oxide reduction and crystallization, opening the possibility for local topographical, chemical, and structural modifications within a biocompatible, amorphous, and semiconducting matrix. The sensitivity is shown to vary significantly with the annealing temperature of as-deposited films. Well-defined irradiation conditions in terms of probe current IP (5 microA) and beam size were achieved with an electron probe microanalyzer. As shown by atomic force and optical microscopy, micro-Raman spectroscopy, wavelength-dispersive X-ray (WDX), and Auger analyses, e-beam exposure below 1 Acm-2 immediately leads to electron-stimulated oxygen desorption, resulting in a well-defined volume loss primarily limited to the irradiated zone under the electron probe and in a blue color shift in this zone because of the presence of Ti2O3. Irradiation at 5 Acm(-2) (IP = 5 microA) results in local crystallization into anatase phase within 1 s of exposure and in reduction to TiO after an extended exposure of 60 s. Further reduction to the metallic state could be observed after 60 s of exposure at approximately 160 Acm(-2). The local reduction could be qualitatively sensed with WDX analysis and Auger line scans. An estimation of the film temperature in the beam center indicates that crystallization occurs at less than 150 degrees C, well below the atmospheric crystallization temperature of the present films. The high e-beam sensitivity in combination with the well-defined volume loss from oxygen desorption allows for precise electron lithographic topographical patterning of the present oxides. Irradiation effects leading to the observed reduction and crystallization phenomena under moderate electron energies are discussed.

Ecological risk assessment of copper and cadmium in surface waters of Chesapeake Bay watershed

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hall, L.W. Jr.; Scott, M.C.; Killen, W.D.

1998-06-01

This ecological risk assessment was designed to characterize risk of copper and cadmium exposure in the Chesapeake Bay watershed by comparing the probability distributions of environmental exposure concentrations with the probability distributions of species response data determined from laboratory studies. The overlap of these distributions was a measure of risk to aquatic life. Dissolved copper and cadmium exposure data were available from six primary data sources covering 102 stations in 18 basins in the Chesapeake Bay watershed from 1985 through 1996. Highest environmental concentrations of copper (based on 90th percentiles) were reported in the Chesapeake and Delaware (C and D)more » Canal, Choptank River, Middle River, and Potomac River; the lowest concentrations of copper were reported in the lower and middle mainstem Chesapeake Bay and Nanticoke River. Based on the calculation of 90th percentiles, cadmium concentrations were highest in the C and D Canal, Potomac River, Upper Chesapeake Bay, and West Chesapeake watershed. Lowest environmental concentrations of cadmium were reported in the lower and middle mainstem Chesapeake Bay and Susquehanna River. The ecological effects data used for this risk assessment were derived primarily from acute copper and cadmium laboratory toxicity tests conducted in both fresh water and salt water; chronic data were much more limited. The 10th percentile (concentration protecting 90% of the species) for all species derived from the freshwater acute copper toxicity database was 8.3 {micro}g/L. For acute saltwater copper data, the 10th percentile for all species was 6.3 {micro}g/L copper. The acute 10th percentile for all saltwater species was 31.7 {micro}g/L cadmium. Highest potential ecological risk from copper exposures was reported in the C and D Canal area of the northern Chesapeake Bay watershed.« less

Treatment of micro air bubbles in rat adipose tissue at 25 kPa altitude exposures with perfluorocarbon emulsions and nitric oxide.

PubMed

Randsøe, Thomas; Hyldegaard, O

2014-01-01

Perfluorocarbon emulsions (PFC) and nitric oxide (NO) releasing agents have on experimental basis demonstrated therapeutic properties in treating and preventing the formation of venous gas embolism as well as increased survival rate during decompression sickness from diving. The effect is ascribed to an increased solubility and transport capacity of respiratory gases in the PFC emulsion and possibly enhanced nitrogen washout through NO-increased blood flow rate and/or the removal of endothelial micro bubble nuclei precursors. Previous reports have shown that metabolic gases (i.e., oxygen in particular) and water vapor contribute to bubble growth and stabilization during altitude exposures. Accordingly, we hypothesize that the administration of PFC and NO donors upon hypobaric pressure exposures either (1) enhance the bubble disappearance rate through faster desaturation of nitrogen, or in contrast (2) promote bubble growth and stabilization through an increased oxygen supply. In anesthetized rats, micro air bubbles (containing 79% nitrogen) of 4-500 nl were injected into exposed abdominal adipose tissue. Rats were decompressed in 36 min to 25 kPa (~10,376 m above sea level) and bubbles studied for 210 min during continued oxygen breathing (FIO2 = 1). Rats were administered PFC, NO, or combined PFC and NO. In all groups, most bubbles grew transiently, followed by a stabilization phase. There were no differences in the overall bubble growth or decay between groups or when compared with previous data during oxygen breathing alone at 25 kPa. During extreme altitude exposures, the contribution of metabolic gases to bubble growth compromises the therapeutic effects of PFC and NO, but PFC and NO do not induce additional bubble growth.

Tea polyphenol epigallocatechin 3-gallate impedes the anti-apoptotic effects of low-grade repetitive stress through inhibition of Akt and NFkappaB survival pathways.

PubMed

Sen, Prosenjit; Chakraborty, Prabir Kumar; Raha, Sanghamitra

2006-01-09

V79 Chinese Hamster lung fibroblasts were subjected to repetitive low-grade stress through multiple exposures to 30 microM H2O2 in culture for 4 weeks. Akt/protein kinase B became phosphorylated at serine473 and threonine308 during this period of repetitive stress. Concurrent exposure of the cells to LY294002 (5 microM), a phosphoinositide-3 kinase inhibitor or 4.5 microM epigallocatechin 3-gallate (EGCG), a tea polyphenol almost completely blocked Akt activation by repetitive stress. Phosphorylation of I kappa B kinase (IKK) and transcriptional activity driven by nuclear factor kappa B (NFkappaB) were significantly enhanced by repetitive oxidative stress. These increases were largely abolished by simultaneous exposure to EGCG. The repetitively stressed cells demonstrated a significant resistance to apoptosis by subsequent acute stress in the form of ultraviolet radiation at 5 J/m2 or H2O2 (7.5 mM). The resistance to apoptosis conferred by repetitive stress was drastically reduced (>80%) by constant exposure to EGCG during the stress period while the presence of LY294002 or the NFkappaB inhibitor SN50 brought about a relatively moderate effect (about 50-65%). Our data indicate that activation of Akt and NFkappaB pro-survival pathways by repetitive low-grade stress results in a strong inhibition of the normal apoptotic response after subsequent acute stress. The tea polyphenol EGCG impedes the activation of both Akt and NFkappaB by repetitive stress and as a result preserves the normal apoptotic response during subsequent acute stress.

Lead exposure in an urban community: investigation of risk factors and assessment of the impact of lead abatement measures.

PubMed

de Freitas, Clarice Umbelino; De Capitani, Eduardo Mello; Gouveia, Nelson; Simonetti, Marcia Helena; de Paula E Silva, Mario Ramos; Kira, Carmen Silvia; Sakuma, Alice Momoyo; de Fátima Henriques Carvalho, Maria; Duran, Maria Cristina; Tiglea, Paulo; de Abreu, Maria Helena

2007-03-01

A battery recycling plant located in an urbanized area contaminated the environment with lead oxides. The Secretary of Environment of the State of São Paulo demanded an evaluation of lead exposure among the population in the vicinity of the plant. To assess the lead exposure of children, to propose control measures and evaluate the impact of these measures. Cross-sectional study of all children<13 years old in a radius of 1km from the plant responsible for the contamination. Blood lead levels (BLL) were determined for each child and questionnaires were applied to their parents. Mean BLL were compared before and after control measures were implemented. Logistic regression identified risk factors of lead exposure. Of the 850 investigated children, 311 presented BLL above the action limit established by the World Health Organization. Overall, the median BLL was 7.3 micro g/dL and it varied according to age of children (higher among 1-5 years old) and distance of the residence from the plant. Risk factors identified for BLL>10 micro g/dL were: to live in unpaved areas, parent working in the plant, distance from the plant, to play on the ground, pica, and to drink locally produced milk. After control measures were implemented (closing the plant, soil removal, dust vacuum-cleaning in the households, etc.), a reduction of 46% in BLL was observed considering the 241 re-evaluated children with levels >10 micro g/dL. This study showed that combined abatement measures were effective in reducing BLL in children living close to a contaminating source. These results informed the decision-making process regarding management of contaminated areas in Brazil.

Influence of statins on distinct circulating microRNAs during prolonged aerobic exercise

PubMed Central

Min, Pil-Ki; Park, Joseph; Isaacs, Stephanie; Taylor, Beth A.; Thompson, Paul D.; Troyanos, Chris; D'Hemecourt, Pierre; Dyer, Sophia; Baggish, Aaron L.

2015-01-01

Statins exacerbate exercise-induced skeletal muscle injury. Muscle-specific microRNAs (myomiRs) increase in plasma after prolonged exercise, but the patterns of myomiRs release after statin-associated muscle injury have not been examined. We examined the relationships between statin exposure, in vitro and in vivo muscle contraction, and expression of candidate circulating myomiRs. We measured plasma levels of myomiRs, circulating microRNA-1 (c-miR-1), c-miR-133a, c-miR-206, and c-miR-499-5p from 28 statin-using and 28 nonstatin-using runners before (PRE), immediately after (FINISH), and 24 h after they ran a 42-km footrace (the 2011 Boston marathon) (POST-24). To examine these cellular-regulation myomiRs, we used contracting mouse C2C12 myotubes in culture with and without statin exposure to compare intracellular and extracellular expression of these molecules. In marathoners, c-miR-1, c-miR-133a, and c-miR-206 increased at FINISH, returned to baseline at POST-24, and were unaffected by statin use. In contrast, c-miR-499-5p was unchanged at FINISH but increased at POST-24 among statin users compared with PRE and runners who did not take statins. In cultured C2C12 myotubes, extracellular c-miR-1, c-miR-133a, and c-miR-206 were significantly increased by muscle contraction regardless of statin use. In contrast, extracellular miR-499-5p was unaffected by either isolated statin exposure or isolated carbachol exposure but it was increased when muscle contraction was combined with statin exposure. In summary, we found that statin-potentiated muscle injury during exercise is accompanied by augmented extracellular release of miR-499-5p. Thus c-miR-499-5p may serve as a biomarker of statin-potentiated muscle damage. PMID:26472872

Postnatal choline supplementation selectively attenuates hippocampal microRNA alterations associated with developmental alcohol exposure

PubMed Central

Balaraman, Sridevi; Idrus, Nirelia M.; Miranda, Rajesh C.; Thomas, Jennifer D.

2017-01-01

Prenatal alcohol exposure can result in a range of physical, neuropathological, and behavioral alterations, collectively termed fetal alcohol spectrum disorders (FASD). We have shown that supplementation with the nutrient choline reduces the severity of developmental alcohol-associated deficits in hippocampal-dependent behaviors and normalizes some aspects of hippocampal cholinergic development and DNA methylation patterns. Alcohol’s developmental effects may also be mediated, in part, by altering microRNAs (miRNAs) that serve as negative regulators of gene translation. To determine whether choline supplementation alters ethanol’s long-lasting effects on miRNAs, Sprague-Dawley rats were exposed to 5.25 g/kg/day ethanol from postnatal days (PD) 4–9 via intubation; controls received sham intubations. Subjects were treated with choline chloride (100 mg/kg/day) or saline vehicle subcutaneously (s.c.) from PD 4–21. On PD 22, subjects were sacrificed, and RNA isolated from the hippocampus. MiRNA expression was assessed with TaqMan Human MicroRNA Panel Low-Density Arrays. Ethanol significantly increased miRNA expression variance, an effect that was normalized with choline supplementation. Cluster analysis of stably expressed miRNAs that exceeded an ANOVA p<0.05 criterion indicated that for both male and female offspring, control and ethanol-exposed groups were most dissimilar from each other, with choline-supplemented groups in between. MiRNAs that expressed an average 2-fold change due to ethanol exposure were further analyzed to identify which ethanol-sensitive miRNAs were protected by choline supplementation. We found that at a false discovery rate (FDR)-adjusted criterion of p<0.05, miR-200c was induced by ethanol exposure and that choline prevented this effect. Collectively, our data show that choline supplementation can normalize disturbances in miRNA expression following developmental alcohol exposure and can protect specific miRNAs from induction by ethanol. These findings have important implications for the mechanisms by which choline may serve as a potential treatment for FASD. PMID:28433422

Urinary microRNAs as potential biomarkers of pesticide exposure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weldon, Brittany A.; Shubin, Sara Pacheco; Smith,

MicroRNAs (miRNAs) are post-transcriptional regulators that silence messenger RNAs. Because miRNAs are stable at room temperature and long-lived, they have been proposed as molecular biomarkers to monitor disease and exposure status. While urinary miRNAs have been used clinically as potential diagnostic markers for kidney and bladder cancers and other diseases, their utility in non-clinical settings has yet to be fully developed. Our goal was to investigate the potential for urinary miRNAs to act as biomarkers of pesticide exposure and early biological response by identifying the miRNAs present in urine from 27 parent/child, farmworker/non-farmworker pairs (16FW/11NFW) collected during two agricultural seasonsmore » (thinning and post-harvest) and characterizing the between- and within-individual variability of these miRNA epigenetic regulators. MiRNAs were isolated from archived urine samples and identified using PCR arrays. Comparisons were made between age, households, season, and occupation. Of 384 miRNAs investigated, 297 (77%) were detectable in at least one sample. Seven miRNAs were detected in at least 50% of the samples, and one miRNA was present in 96% of the samples. Principal components and hierarchical clustering analyses indicate significant differences in miRNA profiles between farmworker and non-farmworker adults as well as between seasons. Six miRNAs were observed to be positively associated with farmworkers status during the post-harvest season. Expression of five of these miRNA trended towards a positive dose response relationship with organophosphate pesticide metabolites in farmworkers. These results suggest that miRNAs may be novel biomarkers of pesticide exposure and early biological response. - Highlights: • A novel method to identify microRNA biomarkers in urinary samples is proposed. • Six miRNAs have been identified as associated with occupational farm work and pesticide exposure. • An observed seasonal difference suggests transient characteristics of urinary miRNAs.« less

Enhancement of Wound Healing by Non-Thermal N2/Ar Micro-Plasma Exposure in Mice with Fractional-CO2-Laser-Induced Wounds.

PubMed

Shao, Pei-Lin; Liao, Jiunn-Der; Wong, Tak-Wah; Wang, Yi-Cheng; Leu, Steve; Yip, Hon-Kan

2016-01-01

Micro-plasma is a possible alternative treatment for wound management. The effect of micro-plasma on wound healing depends on its composition and temperature. The authors previously developed a capillary-tube-based micro-plasma system that can generate micro-plasma with a high nitric oxide-containing species composition and mild working temperature. Here, the efficacy of micro-plasma treatment on wound healing in a laser-induced skin wound mouse model was investigated. A partial thickness wound was created in the back skin of each mouse and then treated with micro-plasma. Non-invasive methods, namely wound closure kinetics, optical coherence tomography (OCT), and laser Doppler scanning, were used to measure the healing efficiency in the wound area. Neo-tissue growth and the expressions of matrix metallopeptidase-3 (MMP-3) and laminin in the wound area were assessed using histological and immunohistochemistry (IHC) analysis. The results show that micro-plasma treatment promoted wound healing. Micro-plasma treatment significantly reduced the wound bed region. The OCT images and histological analysis indicates more pronounced tissue regrowth in the wound bed region after micro-plasma treatment. The laser Doppler images shows that micro-plasma treatment promoted blood flow in the wound bed region. The IHC results show that the level of laminin increased in the wound bed region after micro-plasma treatment, whereas the level of MMP-3 decreased. Based on these results, micro-plasma has potential to be used to promote the healing of skin wounds clinically.

Enhancement of Wound Healing by Non-Thermal N2/Ar Micro-Plasma Exposure in Mice with Fractional-CO2-Laser-Induced Wounds

PubMed Central

Shao, Pei-Lin; Liao, Jiunn-Der; Wong, Tak-Wah; Wang, Yi-Cheng; Leu, Steve; Yip, Hon-Kan

2016-01-01

Micro-plasma is a possible alternative treatment for wound management. The effect of micro-plasma on wound healing depends on its composition and temperature. The authors previously developed a capillary-tube-based micro-plasma system that can generate micro-plasma with a high nitric oxide-containing species composition and mild working temperature. Here, the efficacy of micro-plasma treatment on wound healing in a laser-induced skin wound mouse model was investigated. A partial thickness wound was created in the back skin of each mouse and then treated with micro-plasma. Non-invasive methods, namely wound closure kinetics, optical coherence tomography (OCT), and laser Doppler scanning, were used to measure the healing efficiency in the wound area. Neo-tissue growth and the expressions of matrix metallopeptidase-3 (MMP-3) and laminin in the wound area were assessed using histological and immunohistochemistry (IHC) analysis. The results show that micro-plasma treatment promoted wound healing. Micro-plasma treatment significantly reduced the wound bed region. The OCT images and histological analysis indicates more pronounced tissue regrowth in the wound bed region after micro-plasma treatment. The laser Doppler images shows that micro-plasma treatment promoted blood flow in the wound bed region. The IHC results show that the level of laminin increased in the wound bed region after micro-plasma treatment, whereas the level of MMP-3 decreased. Based on these results, micro-plasma has potential to be used to promote the healing of skin wounds clinically. PMID:27248979

A Data-Driven Framework for Incorporating New Tools for Toxicity, Exposure, and Risk Assessment

EPA Science Inventory

This talk was given during the “Exposure-Based Toxicity Testing” session at the annual meeting of the International Society for Exposure Science. It provided an update on the state of the science and tools that may be employed in risk-based prioritization efforts. It ...

Modulation of oxidative stress by beta-carotene in chicken embryo fibroblasts.

PubMed

Lawlor, S M; O'Brien, N M

1995-06-01

The ability of beta-carotene to protect against oxidative stress in vitro was assessed. Primary cultures of chicken embryo fibroblasts (CEF) were oxidatively stressed by exposure to paraquat (PQ). Activities of the antioxidant enzymes superoxide dismutase (SOD; EC 1.15.1.1), catalase (CAT; EC 1.11.1.6) and glutathione peroxidase (GSH-Px; EC 1.11.19) were measured as indices of oxidative stress. CEF incubated with 0.25 mM-PQ for 18 h exhibited increased SOD and CAT activities and decreased GSH-Px activity compared with the control (P < 0.001). Incorporation of added beta-carotene (0.1 microM) into 0.25 mM-PQ-treated CEF returned SOD activity to that seen in non-PQ-treated cells. beta-Carotene (0.1 microM) reduced the CAT activity from that seen in PQ-treated cells and returned the GSH-Px activity to its control value thus protecting the cells against PQ-induced oxidative stress. However, at higher concentrations of beta-carotene (10 microM), SOD and CAT activities increased significantly (P < 0.001) relative to non-PQ-treated cells and GSH-Px activity decreased relative to its control value. Similar trends were observed when CEF grown in beta-carotene-enriched media (0.1-10 microM) were oxidatively stressed by exposure to 0.25 mM-PQ for 18 h.

Comparative study of cyanotoxins affecting cytoskeletal and chromatin structures in CHO-K1 cells.

PubMed

Gácsi, Mariann; Antal, Otilia; Vasas, Gábor; Máthé, Csaba; Borbély, György; Saker, Martin L; Gyori, János; Farkas, Anna; Vehovszky, Agnes; Bánfalvi, Gáspár

2009-06-01

In this study we compared the effects of the two frequently occuring and most dangerous cyanobacterial toxins on the cellular organization of microfilaments, microtubules and on the chromatin structure in Chinese hamster ovary (CHO-K1) cells. These compounds are the widely known microcystin-LR (MC-LR) and cylindrospermopsin (CYN) classified as the highest-priority cyanotoxin. Toxic effects were tested in a concentration and time dependent manner. The hepatotoxic MC-LR did not cause significant cytotoxicity on CHO-K1 cells under 20 microM, but caused apoptotic changes at higher concentrations. Apoptotic shrinkage was associated with the shortening and loss of actin filaments and with a concentration dependent depolymerization of microtubules. No necrosis was observed over the concentration range (1-50 microM MC-LR) tested. Cylindrospermopsin did cause apoptosis at low concentrations (1-2 microM) and over short exposure periods (12h). Necrosis was observed at higher concentrations (5-10 microM) and following longer exposure periods (24 or 48h). Cyanotoxins also affected the chromatin structure. The condensation process was inhibited by MC-LR at a later stage and manifested as broken elongated prechromosomes. CYN inhibited chromatin condensation at the early fibrillary stage leading to blurred fluorescent images of apoptotic bodies and preventing the formation of metaphase chromosomes. Cylindrospermopsin exhibited a more pronounced toxic effect causing cytoskeletal and nuclear changes as well as apoptotic and necrotic alterations.

Systematically Extracting Metal- and Solvent-Related Occupational Information from Free-Text Responses to Lifetime Occupational History Questionnaires

PubMed Central

Friesen, Melissa C.; Locke, Sarah J.; Tornow, Carina; Chen, Yu-Cheng; Koh, Dong-Hee; Stewart, Patricia A.; Purdue, Mark; Colt, Joanne S.

2014-01-01

Objectives: Lifetime occupational history (OH) questionnaires often use open-ended questions to capture detailed information about study participants’ jobs. Exposure assessors use this information, along with responses to job- and industry-specific questionnaires, to assign exposure estimates on a job-by-job basis. An alternative approach is to use information from the OH responses and the job- and industry-specific questionnaires to develop programmable decision rules for assigning exposures. As a first step in this process, we developed a systematic approach to extract the free-text OH responses and convert them into standardized variables that represented exposure scenarios. Methods: Our study population comprised 2408 subjects, reporting 11991 jobs, from a case–control study of renal cell carcinoma. Each subject completed a lifetime OH questionnaire that included verbatim responses, for each job, to open-ended questions including job title, main tasks and activities (task), tools and equipment used (tools), and chemicals and materials handled (chemicals). Based on a review of the literature, we identified exposure scenarios (occupations, industries, tasks/tools/chemicals) expected to involve possible exposure to chlorinated solvents, trichloroethylene (TCE) in particular, lead, and cadmium. We then used a SAS macro to review the information reported by study participants to identify jobs associated with each exposure scenario; this was done using previously coded standardized occupation and industry classification codes, and a priori lists of associated key words and phrases related to possibly exposed tasks, tools, and chemicals. Exposure variables representing the occupation, industry, and task/tool/chemicals exposure scenarios were added to the work history records of the study respondents. Our identification of possibly TCE-exposed scenarios in the OH responses was compared to an expert’s independently assigned probability ratings to evaluate whether we missed identifying possibly exposed jobs. Results: Our process added exposure variables for 52 occupation groups, 43 industry groups, and 46 task/tool/chemical scenarios to the data set of OH responses. Across all four agents, we identified possibly exposed task/tool/chemical exposure scenarios in 44–51% of the jobs in possibly exposed occupations. Possibly exposed task/tool/chemical exposure scenarios were found in a nontrivial 9–14% of the jobs not in possibly exposed occupations, suggesting that our process identified important information that would not be captured using occupation alone. Our extraction process was sensitive: for jobs where our extraction of OH responses identified no exposure scenarios and for which the sole source of information was the OH responses, only 0.1% were assessed as possibly exposed to TCE by the expert. Conclusions: Our systematic extraction of OH information found useful information in the task/chemicals/tools responses that was relatively easy to extract and that was not available from the occupational or industry information. The extracted variables can be used as inputs in the development of decision rules, especially for jobs where no additional information, such as job- and industry-specific questionnaires, is available. PMID:24590110

Propofol-induced rno-miR-665 targets BCL2L1 and influences apoptosis in rodent developing hippocampal astrocytes.

PubMed

Sun, Wen-Chong; Liang, Zuo-Di; Pei, Ling

2015-12-01

Propofol exerts neurotoxic effects on the developing mammalian brains, but the underlying molecular mechanism remains unclear. MicroRNAs (miRNAs) are a class of small noncoding RNAs that modulate gene expression at the post-transcriptional level. However, in specific types of neurocytes, the detailed functions of miRNAs were not entirely understood. We investigated the potential role of miRNAs in astrocyte pathogenesis caused by propofol. We performed genome-wide microRNA expression profiling in immature cultured hippocampal astrocytes by microarray analysis and predicted their targets and functions using bioinformatics tools. The functional effects of one differentially expressed miRNA were examined experimentally in relation to astrocyte viability. The results showed that 13 miRNAs were significantly differentially expressed after both short-term exposure to high-concentration propofol (10 μg/ml for 1h) and long-term exposure to low-concentration propofol (0.9 μg/ml for 48 h), including rno-miR-665, differing significantly between the 2. Bioinformatics predicted putative binding sites for rno-miR-665 existing in the 3'-untranslated region of Bcl-2-like protein 1 BCL2L1 (Bcl-xl) mRNA. Moreover, such relationship was assessed by luciferase reporter assay, qRT-PCR and western blot. Rno-miR-665 which was significantly up-regulated by propofol can suppress BCL2L1 and elevate cleaved caspase-3 expression in immature astrocytes in vitro. Apoptosis of developing hippocampal astrocytes was thus significantly influenced by propofol or rno-miR-665, or both. Taken together, rno-miR-665 is involved in the neurotoxicity induced by propofol via a caspase-3 mediated mechanism by negatively regulating BCL2L1. It might act as an alternative therapeutic target for treatment of neurological disorders in peadiatric prolonged anesthesia or sedation with propofol clinically. Copyright © 2015. Published by Elsevier B.V.

Micro- and nanodevices integrated with biomolecular probes.

PubMed

Alapan, Yunus; Icoz, Kutay; Gurkan, Umut A

2015-12-01

Understanding how biomolecules, proteins and cells interact with their surroundings and other biological entities has become the fundamental design criterion for most biomedical micro- and nanodevices. Advances in biology, medicine, and nanofabrication technologies complement each other and allow us to engineer new tools based on biomolecules utilized as probes. Engineered micro/nanosystems and biomolecules in nature have remarkably robust compatibility in terms of function, size, and physical properties. This article presents the state of the art in micro- and nanoscale devices designed and fabricated with biomolecular probes as their vital constituents. General design and fabrication concepts are presented and three major platform technologies are highlighted: microcantilevers, micro/nanopillars, and microfluidics. Overview of each technology, typical fabrication details, and application areas are presented by emphasizing significant achievements, current challenges, and future opportunities. Copyright © 2015 Elsevier Inc. All rights reserved.

Electrochemical micro/nano-machining: principles and practices.

PubMed

Zhan, Dongping; Han, Lianhuan; Zhang, Jie; He, Quanfeng; Tian, Zhao-Wu; Tian, Zhong-Qun

2017-03-06

Micro/nano-machining (MNM) is becoming the cutting-edge of high-tech manufacturing because of the increasing industrial demand for supersmooth surfaces and functional three-dimensional micro/nano-structures (3D-MNS) in ultra-large scale integrated circuits, microelectromechanical systems, miniaturized total analysis systems, precision optics, and so on. Taking advantage of no tool wear, no surface stress, environmental friendliness, simple operation, and low cost, electrochemical micro/nano-machining (EC-MNM) has an irreplaceable role in MNM. This comprehensive review presents the state-of-art of EC-MNM techniques for direct writing, surface planarization and polishing, and 3D-MNS fabrications. The key point of EC-MNM is to confine electrochemical reactions at the micro/nano-meter scale. This review will bring together various solutions to "confined reaction" ranging from electrochemical principles through technical characteristics to relevant applications.

Micro-scale Spatial Clustering of Cholera Risk Factors in Urban Bangladesh.

PubMed

Bi, Qifang; Azman, Andrew S; Satter, Syed Moinuddin; Khan, Azharul Islam; Ahmed, Dilruba; Riaj, Altaf Ahmed; Gurley, Emily S; Lessler, Justin

2016-02-01

Close interpersonal contact likely drives spatial clustering of cases of cholera and diarrhea, but spatial clustering of risk factors may also drive this pattern. Few studies have focused specifically on how exposures for disease cluster at small spatial scales. Improving our understanding of the micro-scale clustering of risk factors for cholera may help to target interventions and power studies with cluster designs. We selected sets of spatially matched households (matched-sets) near cholera case households between April and October 2013 in a cholera endemic urban neighborhood of Tongi Township in Bangladesh. We collected data on exposures to suspected cholera risk factors at the household and individual level. We used intra-class correlation coefficients (ICCs) to characterize clustering of exposures within matched-sets and households, and assessed if clustering depended on the geographical extent of the matched-sets. Clustering over larger spatial scales was explored by assessing the relationship between matched-sets. We also explored whether different exposures tended to appear together in individuals, households, and matched-sets. Household level exposures, including: drinking municipal supplied water (ICC = 0.97, 95%CI = 0.96, 0.98), type of latrine (ICC = 0.88, 95%CI = 0.71, 1.00), and intermittent access to drinking water (ICC = 0.96, 95%CI = 0.87, 1.00) exhibited strong clustering within matched-sets. As the geographic extent of matched-sets increased, the concordance of exposures within matched-sets decreased. Concordance between matched-sets of exposures related to water supply was elevated at distances of up to approximately 400 meters. Household level hygiene practices were correlated with infrastructure shown to increase cholera risk. Co-occurrence of different individual level exposures appeared to mostly reflect the differing domestic roles of study participants. Strong spatial clustering of exposures at a small spatial scale in a cholera endemic population suggests a possible role for highly targeted interventions. Studies with cluster designs in areas with strong spatial clustering of exposures should increase sample size to account for the correlation of these exposures.

Use of non-standardised micro-destructive techniques in the characterization of traditional construction materials

NASA Astrophysics Data System (ADS)

Ioannou, Ioannis; Theodoridou, Magdalini; Modestou, Sevasti; Fournari, Revecca; Dagrain, Fabrice

2013-04-01

The characterization of material properties and the diagnosis of their state of weathering and conservation are three of the most important steps in the field of cultural heritage preservation. Several standardised experimental methods exist, especially for determining the material properties and their durability. However, they are limited in their application by the required size of test specimens and the controlled laboratory conditions needed to undertake the tests; this is especially true when the materials under study constitute immovable parts of heritage structures. The current use of other advanced methods of analysis, such as imaging techniques, in the aforementioned field of research offers invaluable results. However, these techniques may not always be accessible to the wider research community due to their complex nature and relatively high cost of application. This study presents innovative applications of two recently developed cutting techniques; the portable Drilling Resistance Measuring System (DRMS) and the scratch tool. Both methods are defined as micro-destructive, since they only destroy a very small portion of sample material. The general concept of both methods lies within the forces needed to cut a material by linear (scratch tool) or rotational (DRMS) cutting action; these forces are related to the mechanical properties of the material and the technological parameters applied on the tool. Therefore, for a given testing configuration, the only parameter influencing the forces applied is the strength of the material. These two techniques have been used alongside a series of standardised laboratory tests aiming at the correlation of various stone properties (density, porosity, dynamic elastic modulus and uniaxial compressive strength). The results prove the potential of both techniques in assessing the uniaxial compressive strength of stones. The scratch tool has also been used effectively to estimate the compressive strength of mud bricks. It therefore follows that both micro-destructive techniques may prove useful in the physico-mechanical characterization of materials which demand in-situ measurements or allow very limited sampling. Moreover, both techniques have been used, for the first time, to map the distribution of salts in building stone in the laboratory; micro-drilling was also applied in the same context in-situ. The results of the laboratory tests performed on limestone impregnated with sodium and magnesium sulfate confirm that both the scratch tool and the DRMS may successfully detect the location of the salt front, as they respond to pore clogging by salt crystals by providing increased scratching/drilling resistance values. Drilling and scratching of duplicate samples treated with a hydrophobic product show the sensitivity of both techniques as they clearly detect changes to the salt front location (i.e. cryptoflorescence) caused by surface treatments. Both techniques were also successful in highlighting the difference in the crystallisation location and pattern of magnesium sulphate and sodium chloride. In-situ application of the micro-drilling test demonstrated its potential for use in the assessment of masonry salt weathering; the results suggest that this technique may, in fact, be useful as a preventive measure against salt damage. Last but not least, both aforementioned novel micro-destructive techniques have been used to assess the effectiveness of commercially available consolidants. The results of the scratch tool have also been utilised to develop a tomography image of the samples under test. Scratching tomography may potentially be combined with in-situ micro-drilling tests to evaluate the effectiveness of consolidation treatments applied on monuments and historic buildings.

Micro-computed tomography imaging and analysis in developmental biology and toxicology.

PubMed

Wise, L David; Winkelmann, Christopher T; Dogdas, Belma; Bagchi, Ansuman

2013-06-01

Micro-computed tomography (micro-CT) is a high resolution imaging technique that has expanded and strengthened in use since it was last reviewed in this journal in 2004. The technology has expanded to include more detailed analysis of bone, as well as soft tissues, by use of various contrast agents. It is increasingly applied to questions in developmental biology and developmental toxicology. Relatively high-throughput protocols now provide a powerful and efficient means to evaluate embryos and fetuses subjected to genetic manipulations or chemical exposures. This review provides an overview of the technology, including scanning, reconstruction, visualization, segmentation, and analysis of micro-CT generated images. This is followed by a review of more recent applications of the technology in some common laboratory species that highlight the diverse issues that can be addressed. Copyright © 2013 Wiley Periodicals, Inc.

Statistical estimation of femur micro-architecture using optimal shape and density predictors.

PubMed

Lekadir, Karim; Hazrati-Marangalou, Javad; Hoogendoorn, Corné; Taylor, Zeike; van Rietbergen, Bert; Frangi, Alejandro F

2015-02-26

The personalization of trabecular micro-architecture has been recently shown to be important in patient-specific biomechanical models of the femur. However, high-resolution in vivo imaging of bone micro-architecture using existing modalities is still infeasible in practice due to the associated acquisition times, costs, and X-ray radiation exposure. In this study, we describe a statistical approach for the prediction of the femur micro-architecture based on the more easily extracted subject-specific bone shape and mineral density information. To this end, a training sample of ex vivo micro-CT images is used to learn the existing statistical relationships within the low and high resolution image data. More specifically, optimal bone shape and mineral density features are selected based on their predictive power and used within a partial least square regression model to estimate the unknown trabecular micro-architecture within the anatomical models of new subjects. The experimental results demonstrate the accuracy of the proposed approach, with average errors of 0.07 for both the degree of anisotropy and tensor norms. Copyright © 2015 Elsevier Ltd. All rights reserved.

Toxicity of dimethylmonothioarsinic acid toward human epidermoid carcinoma A431 cells.

PubMed

Naranmandura, Hua; Ibata, Kenji; Suzuki, Kazuo T

2007-08-01

Chronic ingestion of arsenic-contaminated drinking water induces skin lesions and urinary bladder cancer in humans. It is now recognized that thioarsenicals such as dimethylmonothioarsinic acid (DMMTA (V)) are commonly excreted in the urine of humans and animals and that the production of DMMTA (V) may be a risk factor for the development of the diseases caused by arsenic. The toxicity of DMMTA (V) was compared with that of related nonthiolated arsenicals with respect to cell viability, uptake ability, generation of reactive oxygen species (ROS), and cell cycle progression of human epidermoid carcinoma A431 cells, arsenate (iAs (V)), arsenite (iAs (III)), dimethylarsinic acid (DMA (V)), and dimethylarsinous acid (DMA (III)) being used as reference nonthiolated arsenicals. DMMTA (V) (LC 50 = 10.7 microM) was shown to be much more cytotoxic than iAs (V) (LC 50 = 571 microM) and DMA (V) (LC 50 = 843 microM), and its potency was shown to be close to that of trivalent arsenicals iAs (III) (LC 50 = 5.49 microM) and DMA (III) (LC 50 = 2.16 microM). The greater cytotoxicity of DMMTA (V) was associated with greater cellular uptake and distribution, and the level of intracellular ROS remarkably increased in A431 cells upon exposure to DMMTA (V) compared to that after exposure to other trivalent arsenicals at the respective LC 50. Exposure of DMMTA (V) to cells for 24 h induced cell cycle perturbation. Namely, the percentage of cells residing in S and G2/M phases increased from 10.2 and 15.6% to 46.5 and 20.8%, respectively. These results suggest that although DMMTA (V) is a pentavalent arsenical, it is taken up efficiently by cells and causes various levels of toxicity, in a manner different from that of nonthiolated pentavalent arsenicals, demonstrating that DMMTA (V) is one of the most toxic arsenic metabolites. The high cytotoxicity of DMMTA (V) was explained and/or proposed by (1) efficient uptake by cells followed by (2) its transformation to DMA (V), (3) producing ROS in the redox equilibrium between DMA (V) and DMA (III) in the presence of glutathione.

Measuring accident risk exposure for pedestrians in different micro-environments.

PubMed

Lassarre, Sylvain; Papadimitriou, Eleonora; Yannis, George; Golias, John

2007-11-01

Pedestrians are mainly exposed to the risk of road accident when crossing a road in urban areas. Traditionally in the road safety field, the risk of accident for pedestrian is estimated as a rate of accident involvement per unit of time spent on the road network. The objective of this research is to develop an approach of accident risk based on the concept of risk exposure used in environmental epidemiology, such as in the case of exposure to pollutants. This type of indicator would be useful for comparing the effects of urban transportation policy scenarios on pedestrian safety. The first step is to create an indicator of pedestrians' exposure, which is based on motorised vehicles' "concentration" by lane and also takes account of traffic speed and time spent to cross. This is applied to two specific micro-environments: junctions and mid-block locations. A model of pedestrians' crossing behaviour along a trip is then developed, based on a hierarchical choice between junctions and mid-block locations and taking account of origin and destination, traffic characteristics and pedestrian facilities. Finally, a complete framework is produced for modelling pedestrians' exposure in the light of their crossing behaviour. The feasibility of this approach is demonstrated on an artificial network and a first set of results is obtained from the validation of the models in observational studies.

State-of-the-art exposure chamber for highly controlled and reproducible THz biological effects studies

NASA Astrophysics Data System (ADS)

Cerna, Cesario Z.; Elam, David P.; Echchgadda, Ibtissam; Sloan, Mark A.; Wilmink, Gerald J.

2014-03-01

Terahertz (THz) imaging and sensing technologies are increasingly being used at international airports for security screening purposes and at major medical centers for cancer and burn diagnosis. The emergence of new THz applications has directly resulted in an increased interest regarding the biological effects associated with this frequency range. Knowledge of THz biological effects is also desired for the safe use of THz systems, identification of health hazards, and development of empirically-based safety standards. In this study, we developed a state-of-the-art exposure chamber that allowed for highly controlled and reproducible studies of THz biological effects. This innovative system incorporated an industry grade cell incubator system that permitted a highly controlled exposure environment, where temperatures could be maintained at 37 °C +/- 0.1 °C, carbon dioxide (CO2) levels at 5% +/- 0.1%, and relative humidity (RH) levels at 95% +/- 1%. To maximize the THz power transmitted to the cell culture region inside the humid incubator, a secondary custom micro-chamber was fabricated and incorporated into the system. This micro-chamber shields the THz beam from the incubator environment and could be nitrogen-purged to eliminate water absorption effects. Additionally, a microscope that allowed for real-time visualization of the live cells before, during, and after THz exposure was integrated into the exposure system.

Synthetic RNAs for Gene Regulation: Design Principles and Computational Tools

PubMed Central

Laganà, Alessandro; Shasha, Dennis; Croce, Carlo Maria

2014-01-01

The use of synthetic non-coding RNAs for post-transcriptional regulation of gene expression has not only become a standard laboratory tool for gene functional studies but it has also opened up new perspectives in the design of new and potentially promising therapeutic strategies. Bioinformatics has provided researchers with a variety of tools for the design, the analysis, and the evaluation of RNAi agents such as small-interfering RNA (siRNA), short-hairpin RNA (shRNA), artificial microRNA (a-miR), and microRNA sponges. More recently, a new system for genome engineering based on the bacterial CRISPR-Cas9 system (Clustered Regularly Interspaced Short Palindromic Repeats), was shown to have the potential to also regulate gene expression at both transcriptional and post-transcriptional level in a more specific way. In this mini review, we present RNAi and CRISPRi design principles and discuss the advantages and limitations of the current design approaches. PMID:25566532

Stoffenmanager exposure model: company-specific exposure assessments using a Bayesian methodology.

PubMed

van de Ven, Peter; Fransman, Wouter; Schinkel, Jody; Rubingh, Carina; Warren, Nicholas; Tielemans, Erik

2010-04-01

The web-based tool "Stoffenmanager" was initially developed to assist small- and medium-sized enterprises in the Netherlands to make qualitative risk assessments and to provide advice on control at the workplace. The tool uses a mechanistic model to arrive at a "Stoffenmanager score" for exposure. In a recent study it was shown that variability in exposure measurements given a certain Stoffenmanager score is still substantial. This article discusses an extension to the tool that uses a Bayesian methodology for quantitative workplace/scenario-specific exposure assessment. This methodology allows for real exposure data observed in the company of interest to be combined with the prior estimate (based on the Stoffenmanager model). The output of the tool is a company-specific assessment of exposure levels for a scenario for which data is available. The Bayesian approach provides a transparent way of synthesizing different types of information and is especially preferred in situations where available data is sparse, as is often the case in small- and medium sized-enterprises. Real-world examples as well as simulation studies were used to assess how different parameters such as sample size, difference between prior and data, uncertainty in prior, and variance in the data affect the eventual posterior distribution of a Bayesian exposure assessment.

Temperature-controlled micro-TLC: a versatile green chemistry and fast analytical tool for separation and preliminary screening of steroids fraction from biological and environmental samples.

PubMed

Zarzycki, Paweł K; Slączka, Magdalena M; Zarzycka, Magdalena B; Bartoszuk, Małgorzata A; Włodarczyk, Elżbieta; Baran, Michał J

2011-11-01

This paper is a continuation of our previous research focusing on development of micro-TLC methodology under temperature-controlled conditions. The main goal of present paper is to demonstrate separation and detection capability of micro-TLC technique involving simple analytical protocols without multi-steps sample pre-purification. One of the advantages of planar chromatography over its column counterpart is that each TLC run can be performed using non-previously used stationary phase. Therefore, it is possible to fractionate or separate complex samples characterized by heavy biological matrix loading. In present studies components of interest, mainly steroids, were isolated from biological samples like fish bile using single pre-treatment steps involving direct organic liquid extraction and/or deproteinization by freeze-drying method. Low-molecular mass compounds with polarity ranging from estetrol to progesterone derived from the environmental samples (lake water, untreated and treated sewage waters) were concentrated using optimized solid-phase extraction (SPE). Specific bands patterns for samples derived from surface water of the Middle Pomerania in northern part of Poland can be easily observed on obtained micro-TLC chromatograms. This approach can be useful as simple and non-expensive complementary method for fast control and screening of treated sewage water discharged by the municipal wastewater treatment plants. Moreover, our experimental results show the potential of micro-TLC as an efficient tool for retention measurements of a wide range of steroids under reversed-phase (RP) chromatographic conditions. These data can be used for further optimalization of SPE or HPLC systems working under RP conditions. Furthermore, we also demonstrated that micro-TLC based analytical approach can be applied as an effective method for the internal standard (IS) substance search. Generally, described methodology can be applied for fast fractionation or screening of the whole range of target substances as well as chemo-taxonomic studies and fingerprinting of complex mixtures, which are present in biological or environmental samples. Due to low consumption of eluent (usually 0.3-1mL/run) mainly composed of water-alcohol binary mixtures, this method can be considered as environmentally friendly and green chemistry focused analytical tool, supplementary to analytical protocols involving column chromatography or planar micro-fluidic devices. Copyright © 2011 Elsevier Ltd. All rights reserved.

Saga, A Small Advanced Geochemistry Assembly With Micro-rover For The Exploration Of Planetary Surfaces

NASA Astrophysics Data System (ADS)

Brueckner, J.; Saga Team

During future lander missions on Mars, Moon, or Mercury, it is highly advisable to extend the reach of instruments and to bring them to the actual sites of interest to measure in-situ selected surface samples (rocks, soils, or regolith). Particularly, geo- chemical measurements (determination of chemistry, mineralogy, and surface texture) are of utmost importance, because they provide key data on the nature of the sur- face samples. The obtained data will contribute to the classification of these samples. On Mars, weathering processes can also be studied provided some grinding tools are available. Also, the existence of ancient water activities, if any, can be searched for (e.g. sediments, hydroxides, hydrated minerals, or evaporates). The combined geo- chemical data sets of several samples and one/or several landing sites provide an im- portant base for the understanding of planetary surface processes and, hence, plan- etary evolution. A light-weight integrated instrument package and a micro-rover is proposed for future geochemical investigations. SAGA (Small Advanced Geochem- istry Assembly) will consist of several small geochemistry instruments and a tool that are packaged in a compact payload cab: the chemical Alpha Particle X-Ray Spec- trometer (APXS), the mineralogical Mössbauer Spectrometer (MIMOS), the textural close-up camera (MIROCAM), and a blower/grinder tool. These instruments have or will get flight heritage on upcoming ESA and NASA missions. The modularity of the concept permits to attach SAGA to any deployment device, specially, to the pro- posed small, lightweight micro-rover (dubbed SAGA?XT). Micro-rover technology has been developed for many years in Europe. One of the most advanced concepts is the tracked micro-rover SNanokhodT, developed recently in the frame of ESASs & cedil; Technology Research Programme (TRP). It has a total mass of about 3.5 kg (includ- ing payload and parts on the lander). This micro-rover is designed to drive to different target sites in the vicinity of a (small) lander. In the framework of the upcoming ESA Aurora programme, the further development of surface-mobile robots will be an im- portant technology area to improve control, navigation, and guidance of a micro-rover and the accurate docking of its instruments on selected targets.

Applications of scientific imaging in environmental toxicology

NASA Astrophysics Data System (ADS)

El-Demerdash, Aref M.

The national goals of clean air, clean water, and healthy ecosystems are a few of the primary forces that drive the need for better environmental monitoring. As we approach the end of the 1990s, the environmental questions at regional to global scales are being redefined and refined in the light of developments in environmental understanding and technological capability. Research in the use of scientific imaging data for the study of the environment is urgently needed in order to explore the possibilities of utilizing emerging new technologies. The objective of this research proposal is to demonstrate the usability of a wealth of new technology made available in the last decade to providing a better understanding of environmental problems. Research is focused in two imaging techniques macro and micro imaging. Several examples of applications of scientific imaging in research in the field of environmental toxicology were presented. This was achieved on two scales, micro and macro imaging. On the micro level four specific examples were covered. First, the effect of utilizing scanning electron microscopy as an imaging tool in enhancing taxa identification when studying diatoms was presented. Second, scanning electron microscopy combined with energy dispersive x-ray analyzer were demonstrated as a valuable and effective tool for identifying and analyzing household dust samples. Third, electronic autoradiography combined with FT-IR microscopy were used to study the distribution pattern of [14C]-Malathion in rats as a result of dermal exposure. The results of the autoradiography made on skin sections of the application site revealed the presence of [ 14C]-activity in the first region of the skin. These results were evidenced by FT-IR microscopy. The obtained results suggest that the penetration of Malathion into the skin and other tissues is vehicle and dose dependent. The results also suggest the use of FT-IR microscopy imaging for monitoring the disposition of insecticides in biological tissues. Finally, in the microscale level, the penetration of household insecticides through different types of textiles fabrics. The results obtained from the fluorescence spectra, SFC and SEM showed that cotton-polyester (twill), cotton, wool and cotton thermal underwear were the least penetrable materials for the aerosols. On the other hand, acrylic and artificial silk (rayon) were the most penetrable cloth types. The most protective form of clothing will be more than one layer e.g. cotton/polyester type of clothing. (Abstract shortened by UMI.)

A Cross-Course Investigation of Integrative Cases for Evolution Education.

PubMed

White, Peter John Thomas; Heidemann, Merle K; Smith, James J

2015-12-01

Evolution is a cornerstone theory in biology, yet many undergraduate students have difficulty understanding it. One reason for this is that evolution is often taught in a macro-scale context without explicit links to micro-scale processes. To address this, we developed a series of integrative evolution cases that present the evolution of various traits from their origin in genetic mutation, to the synthesis of modified proteins, to how these proteins produce novel phenotypes, to the related macro-scale impacts that the novel phenotypes have on populations in ecological communities. We postulated that students would develop a fuller understanding of evolution when learning biology in a context where these integrative evolution cases are used. We used a previously developed assessment tool, the ATEEK (Assessment Tool for Evaluating Evolution Knowledge), within a pre-course/post-course assessment framework. Students who learned biology in courses using the integrative cases performed significantly better on the evolution assessment than did students in courses that did not use the cases. We also found that student understanding of evolution increased with increased exposure to the integrative evolution cases. These findings support the general hypothesis that students acquire a more complete understanding of evolution when they learn about its genetic and molecular mechanisms along with macro-scale explanations.

A Cross-Course Investigation of Integrative Cases for Evolution Education †

PubMed Central

White, Peter John Thomas; Heidemann, Merle K.; Smith, James J.

2015-01-01

Evolution is a cornerstone theory in biology, yet many undergraduate students have difficulty understanding it. One reason for this is that evolution is often taught in a macro-scale context without explicit links to micro-scale processes. To address this, we developed a series of integrative evolution cases that present the evolution of various traits from their origin in genetic mutation, to the synthesis of modified proteins, to how these proteins produce novel phenotypes, to the related macro-scale impacts that the novel phenotypes have on populations in ecological communities. We postulated that students would develop a fuller understanding of evolution when learning biology in a context where these integrative evolution cases are used. We used a previously developed assessment tool, the ATEEK (Assessment Tool for Evaluating Evolution Knowledge), within a pre-course/post-course assessment framework. Students who learned biology in courses using the integrative cases performed significantly better on the evolution assessment than did students in courses that did not use the cases. We also found that student understanding of evolution increased with increased exposure to the integrative evolution cases. These findings support the general hypothesis that students acquire a more complete understanding of evolution when they learn about its genetic and molecular mechanisms along with macro-scale explanations. PMID:26753023

Using exposure prediction tools to link exposure and dosimetry for risk-based decisions: A case study with phthalates

EPA Science Inventory

A few different exposure prediction tools were evaluated for use in the new in vitro-based safety assessment paradigm using di-2-ethylhexyl phthalate (DEHP) and dibutyl phthalate (DnBP) as case compounds. Daily intake of each phthalate was estimated using both high-throughput (HT...

Sustained microgravity reduces the human ventilatory response to hypoxia but not to hypercapnia.

PubMed

Prisk, G K; Elliott, A R; West, J B

2000-04-01

We measured the isocapnic hypoxic ventilatory response and the hypercapnic ventilatory response by using rebreathing techniques in five normal subjects (ages 37-47 yr) before, during, and after 16 days of exposure to microgravity (microG). Control measurements were performed with the subjects in the standing and supine postures. In both microG and in the supine position, the hypoxic ventilatory response, as measured from the slope of ventilation against arterial O(2) saturation, was greatly reduced, being only 46 +/- 10% (microG) and 52 +/- 11% (supine) of that measured standing (P < 0.01). During the hypercapnic ventilatory response test, the ventilation at a PCO(2) of 60 Torr was not significantly different in microG (101 +/- 5%) and the supine position (89 +/- 3%) from that measured standing. Inspiratory occlusion pressures agreed with these results. The findings can be explained by inhibition of the hypoxic but not hypercapnic drive, possibly as a result of an increase in blood pressure in carotid baroreceptors in microG and the supine position.

Micro-CT image reconstruction based on alternating direction augmented Lagrangian method and total variation.

PubMed

Gopi, Varun P; Palanisamy, P; Wahid, Khan A; Babyn, Paul; Cooper, David

2013-01-01

Micro-computed tomography (micro-CT) plays an important role in pre-clinical imaging. The radiation from micro-CT can result in excess radiation exposure to the specimen under test, hence the reduction of radiation from micro-CT is essential. The proposed research focused on analyzing and testing an alternating direction augmented Lagrangian (ADAL) algorithm to recover images from random projections using total variation (TV) regularization. The use of TV regularization in compressed sensing problems makes the recovered image quality sharper by preserving the edges or boundaries more accurately. In this work TV regularization problem is addressed by ADAL which is a variant of the classic augmented Lagrangian method for structured optimization. The per-iteration computational complexity of the algorithm is two fast Fourier transforms, two matrix vector multiplications and a linear time shrinkage operation. Comparison of experimental results indicate that the proposed algorithm is stable, efficient and competitive with the existing algorithms for solving TV regularization problems. Copyright © 2013 Elsevier Ltd. All rights reserved.

Optimal micro-mirror tilt angle and sync mark design for digital micro-mirror device based collinear holographic data storage system.

PubMed

Liu, Jinpeng; Horimai, Hideyoshi; Lin, Xiao; Liu, Jinyan; Huang, Yong; Tan, Xiaodi

2017-06-01

The collinear holographic data storage system (CHDSS) is a very promising storage system due to its large storage capacities and high transfer rates in the era of big data. The digital micro-mirror device (DMD) as a spatial light modulator is the key device of the CHDSS due to its high speed, high precision, and broadband working range. To improve the system stability and performance, an optimal micro-mirror tilt angle was theoretically calculated and experimentally confirmed by analyzing the relationship between the tilt angle of the micro-mirror on the DMD and the power profiles of diffraction patterns of the DMD at the Fourier plane. In addition, we proposed a novel chess board sync mark design in the data page to reduce the system bit error rate in circumstances of reduced aperture required to decrease noise and median exposure amount. It will provide practical guidance for future DMD based CHDSS development.

Progress and profit through microtechnologies: commercial applications of MEMS/MOEMS

NASA Astrophysics Data System (ADS)

Ehrfeld, Wolfgang; Ehrfeld, Ursula

2001-09-01

Micro technology deals with miniaturization and integration in all areas of technology outside of microelectronics like micro mechanics, micro optics, micro acoustics, micro fluid technology, micro reaction technology and further disciplines which are focused on technical components and systems with characteristic dimensions in the micrometer range. Within a period of about ten years a multi-billion dollar market has been set up with many products for daily life. The growth rate of the market of micro technology will remain on a high level for the years to come. Mega trends resulting from fundamental human wishes for health, information, mobility and sustainable development are creating a further growing basis for micro technical products. A broad spectrum of production processes and materials has been developed to meet the requirements of a strongly diversified range of applications. For the development of new components and systems the importance of software tools for simulation of functional properties, production processes and comprehensive optimization is growing rapidly. Micro devices are meanwhile used extensively in information, automotive, and medical technologies. In addition, micro technology is generating a completely novel basis for chemical engineering, life sciences, industrial automation and optical communication, to mention only a few disciplines where future innovation will be dominated by miniaturization.

C-FERST

EPA Pesticide Factsheets

The Community-Focused Exposure and Risk Screening Tool (C-FERST) is an online tool which provides access to resources that can help communities learn more about their environmental issues, and explore exposure and risk reduction options.

Magnetic fields from domestic appliances in the UK.

PubMed

Preece, A W; Kaune, W; Grainger, P; Preece, S; Golding, J

1997-01-01

In a survey of 50 UK homes the 50 Hz fundamental and harmonic magnetic fields generated by 806 domestic appliances found in the homes, and used regularly by mothers, were measured. Measurements were made in the direction of most likely access, and from the surface of the appliances. Mothers completed a questionnaire on the use of appliances and were monitored for 24 h so that acquired exposure could be compared with the measured ambient fields in the home. Appliances were measured at standard distances and an algorithm was used to calculate fields at 100 and 50 cm to remove room background contributions. A few appliances generated fields in excess of 0.2 microT at 1 m: microwave cookers 0.37 +/- 0.14 microT; washing machines 0.27 +/- 0.14 microT; dishwashers 0.23 +/- 0.13 microT; some electric showers 0.11 +/- 0.25 microT and can openers 0.20 +/- 0.21 microT. Of continuously operating devices, only central heating pumps (0.51 +/- 0.47 microT), central heating boilers (0.27 +/- 0.26 microT) and fish-tank air pumps (0.32 +/- 0.09 microT) produced significant fields at 0.5 m. There were no obvious ways to group different types of appliances as high- or low-strength sources. Mothers spent on average about 4.5 h per day in the kitchen, where the strongest sources of magnetic field were located.

Micro-PIXE study of Ag in digestive glands of a nano-Ag fed arthropod ( Porcellio scaber, Isopoda, Crustacea)

NASA Astrophysics Data System (ADS)

Tkalec, Živa Pipan; Drobne, Damjana; Vogel-Mikuš, Katarina; Pongrac, Paula; Regvar, Marjana; Štrus, Jasna; Pelicon, Primož; Vavpetič, Primož; Grlj, Nataša; Remškar, Maja

2011-10-01

Micro-proton induced X-ray emission (micro-PIXE) method was applied to study the micro-localization of silver (Ag) in digestive glands of a terrestrial arthropod (Porcellio scaber) after feeding on silver nanoparticles (nano-Ag) dosed food. The aim of our work was to assess whether feeding on nano-Ag results in the assimilation of silver (Ag) in digestive gland cells. To study micro-localization and elemental distribution of Ag, the animals were fed on food dosed with nanoparticles for 14 days under controlled laboratory conditions. At the end of the feeding exposure, the animals were dissected and digestive glands prepared for micro-PIXE analyses and TEM investigation. The results obtained by micro-PIXE documented high amounts of Ag inside S-cells of the digestive gland epithelium; however, TEM investigation did not show particle aggregates inside digestive gland cells. Also no adverse effect on feeding behavior was recorded what is a measure of toxic effects. We explain the presence of Ag inside the cells as a result of the assimilation of dissoluted Ag ions from ingested nano-Ag particles. Assimilation of excessive amounts of ingested metal ions in S-cells is a well known metal detoxification mechanism in isopods. We discuss the advantages of using micro-PIXE for the micro-localization of elements in biological tissue in studies of interactions between nanoparticles and biological systems.

Noise Exposure Questionnaire (NEQ): A Tool for Quantifying Annual Noise Exposure

PubMed Central

Johnson, Tiffany A.; Cooper, Susan; Stamper, Greta C.; Chertoff, Mark

2017-01-01

Background Exposure to both occupational and non-occupational noise is recognized as a risk factor for noise-induced hearing loss (NIHL). Although audiologists routinely inquire regarding history of noise exposure, there are limited tools available for quantifying this history or for identifying those individuals who are at highest risk for NIHL. Identifying those at highest risk would allow hearing conservation activities to be focused on those individuals. Purpose To develop a detailed, task-based questionnaire for quantifying an individual’s annual noise exposure arising from both occupational and non-occupational sources (aim 1) and to develop a short screening tool that could be used to identify individuals at high risk of NIHL (aim 2). Research Design Review of relevant literature for questionnaire development followed by a cross-sectional descriptive and correlational investigation of the newly developed questionnaire and screening tool. Study Sample One hundred fourteen college freshmen completed the detailed questionnaire for estimating annual noise exposure (aim 1) and answered the potential screening questions (aim 2). An additional 59 adults participated in data collection where the accuracy of the screening tool was evaluated (aim 2). Data Collection and Analysis In study aim 1, all subjects completed the detailed questionnaire and the potential screening questions. Descriptive statistics were used to quantify subject participation in various noisy activities and their associated annual noise exposure estimates. In study aim 2, linear regression techniques were used to identify screening questions that could be used to predict a subject’s estimated annual noise exposure. Clinical decision theory was then used to assess the accuracy with which the screening tool predicted high and low risk of NIHL in a new group of subjects. Results Responses on the detailed questionnaire indicated that our sample of college freshmen reported high rates of participation in a variety of occupational and non-occupational activities associated with high sound levels. Although participation rates were high, annual noise exposure estimates were below highest-risk levels for many subjects because the frequency of participation in these activities was low in many cases. These data illustrate how the Noise Exposure Questionnaire (NEQ) could be used to provide detailed and specific information regarding an individual’s exposure to noise. The results of aim 2 suggest that the screening tool, the 1-Minute Noise Screen, can be used to identify those subjects with high- and low-risk noise exposure, allowing more in-depth assessment of noise exposure history to be targeted at those most at risk. Conclusions The NEQ can be used to estimate an individual’s annual noise exposure and the 1-Minute Noise Screen can be used to identify those subjects at highest risk of NIHL. These tools allow audiologists to focus hearing conservation efforts on those individuals who are most in need of those services. PMID:28054909

A New Individually Addressable Micro-LED Array for Photogenetic Neural Stimulation.

PubMed

McGovern, B; Berlinguer Palmini, R; Grossman, N; Drakakis, E; Poher, V; Neil, M A A; Degenaar, P

2010-12-01

Here, we demonstrate the use of a micro light emitting diode (LED) array as a powerful tool for complex spatiotemporal control of photosensitized neurons. The array can generate arbitrary, 2-D, excitation patterns with millisecond and micrometer resolution. In particular, we describe an active matrix control address system to allow simultaneous control of 256 individual micro LEDs. We present the system optically integrated into a microscope environment and patch clamp electrophysiology. The results show that the emitters have sufficient radiance at the required wavelength to stimulate neurons expressing channelrhodopsin-2 (ChR2).

Micro-Raman Analysis of Irradiated Diamond Films

NASA Technical Reports Server (NTRS)

Newton, R. L.; Munafo, Paul M. (Technical Monitor)

2002-01-01

Owing to its unique and robust physical properties, diamond is a much sought after material for use in advanced technologies such as Microelectromechanical Systems (MEMS). The volume and weight savings promised by MEMS-based devices are of particular interest to spaceflight applications. However, much basic materials science research remains to be completed in this field. Results of micro-Raman analysis of proton (1015 - 1017 H+/cm2 doses) irradiated chemical vapor deposited (CVD) diamond reveals that the microstructure is retained even after high radiation exposure.

A pilot study of the behavior of gas- and particle-phase ETS tracers in residences

DOE Office of Scientific and Technical Information (OSTI.GOV)

Apte, Michael; Gundel, Lara; Dod, Raymond

2002-02-01

Our previous study of environmental tobacco smoke (ETS) in a three-room environmental chamber showed that smoking history significantly influenced inter-room ETS transport, particularly of gas-phase nicotine. We conducted a three-home pilot study where smoking was limited to one room. Single-smoker residences were monitored during five one-week periods while the smoker participated in a smoking cessation program. Nicotine traced ETS particles were detected reliably in the smoking rooms (SRs) and unreliably in the non-smoking rooms (NSRs). On average, the ventilation- and volume-normalized smoking rate, 0.1 Cigarette-h{sup -1} m{sup -3}, added about 17 and 4 {micro}g m{sup -3} of ETS particles intomore » the SR and NSR, while average nicotine concentration increases were 2 and 0.06 {micro}g m{sup -3}, respectively. Thus, nicotine tracers may underestimate ETS particle exposure in a NSR (e.g., a child's bedroom) by a factor of 2 to 8. In other words, ETS exposure predicted from nicotine concentrations could be almost an order of magnitude lower than actual exposure.« less

Reduced expression of brain cannabinoid receptor 1 (Cnr1) is coupled with an increased complementary micro-RNA (miR-26b) in a mouse model of fetal alcohol spectrum disorders.

PubMed

Stringer, Randa L; Laufer, Benjamin I; Kleiber, Morgan L; Singh, Shiva M

2013-08-02

Prenatal alcohol exposure is known to result in fetal alcohol spectrum disorders, a continuum of physiological, behavioural, and cognitive phenotypes that include increased risk for anxiety and learning-associated disorders. Prenatal alcohol exposure results in life-long disorders that may manifest in part through the induction of long-term gene expression changes, potentially maintained through epigenetic mechanisms. Here we report a decrease in the expression of Canabinoid receptor 1 (Cnr1) and an increase in the expression of the regulatory microRNA miR-26b in the brains of adult mice exposed to ethanol during neurodevelopment. Furthermore, we show that miR-26b has significant complementarity to the 3'-UTR of the Cnr1 transcript, giving it the potential to bind and reduce the level of Cnr1 expression. These findings elucidate a mechanism through which some genes show long-term altered expression following prenatal alcohol exposure, leading to persistent alterations to cognitive function and behavioural phenotypes observed in fetal alcohol spectrum disorders.

Experimental test of whether electrostatically charged micro-organisms and their spores contribute to the onset of arcs across vacuum gaps

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grisham, L. R.; Halle, A. von; Carpe, A. F.

2013-12-15

Recently it was proposed [L. R. Grisham et al. Phys. Plasmas 19, 023107 (2012)] that one of the initiators of vacuum voltage breakdown between conducting electrodes might be micro-organisms and their spores, previously deposited during exposure to air, which then become electrostatically charged when an electric potential is applied across the vacuum gap. This note describes a simple experiment to compare the number of voltage-conditioning pulses required to reach the nominal maximum operating voltage across a gap between two metallic conductors in a vacuum, comparing cases in which biological cleaning was done just prior to pump-down with cases where thismore » was not done, with each case preceded by exposure to ambient air for three days. Based upon these results, it does not appear that air-deposited microbes and their spores constitute a major pathway for arc initiation, at least for exposure periods of a few days, and for vacuum gaps of a few millimeters, in the regime where voltage holding is usually observed to vary linearly with gap distance.« less

Application of Tools and Databases to Community-Level Assessments of Exposure, Health and the Environment with Case Study Examples

EPA Science Inventory

The purpose of this report is to assess the application of tools to community-level assessments of exposure, health and the environment. Various tools and datasets provided different types of information, such as on health effects, chemical types and volumes, facility locations a...

Multiple effects of ryanodine on intracellular free Ca2+ in smooth muscle cells from bovine and porcine coronary artery: modulation of sarcoplasmic reticulum function.

PubMed

Wagner-Mann, C; Hu, Q; Sturek, M

1992-04-01

1. The effects of ryanodine and caffeine on intracellular free Ca2+ concentration ([Ca2+]i) were studied by use of fura-2 microfluorometry in single smooth muscle cells freshly dispersed from bovine and porcine coronary artery. 2. Bovine and porcine cells demonstrated similar sensitivities to 10 min of exposure to ryanodine in physiological salt solution (PSS), as determined by comparable dose-dependent decreases in the subsequent [Ca2+]i transient induced by 5 mM caffeine. 3. Ryanodine (10 microM) caused a significant increase in [Ca2+]i to a plateau level 27 +/- 3% and 38 +/- 4% above baseline [Ca2+]i (baseline [Ca2+]i = [Ca2+]i at 0 min) in porcine and bovine cells, respectively, when bathed in PSS. In bovine cells the time required to reach 1/2 the plateau level was only 3 min versus 6 min for porcine cells. 4. The ryanodine-induced plateau increase in [Ca2+]i was 35 +/- 5% above baseline for bovine cells bathed in 0 Ca PSS (PSS including 10 microM EGTA with no added Ca2+), but only 7 +/- 3% above baseline in porcine cells during 10 min exposure to 10 microM ryanodine. In bovine cells [Ca2+]i showed proportional increases when extracellular Ca2+ was increased from the normal 2 mM Ca2+ PSS to 5 and 10 mM. 5. Cells pretreated with caffeine in 0 Ca PSS, which depleted the caffeine-sensitive sarcoplasmic reticulum Ca2+ store, showed no increase in [Ca2+]i when challenged with 10 microM ryanodine. The ryanodine-associated increase in [Ca2+]i, which was sustained in 0 Ca PSS during the 10 min ryanodine exposure in cells not pretreated with caffeine, suggests that ryanodine releases Ca2+ from the sarcoplasmic reticulum, but also inhibits Ca2+ efflux.6. Intracellular free Ba2+ ([Ba24],) was measured with fura-2 microfluorometry to define further the Ca2" efflux pathway inhibited by ryanodine; specifically, Ba2+ is not transported by the Ca2" pump, but will substitute for Ca2" in Na+-Ca24 exchange. In porcine cells pretreated with caffeine in 0 Ca PSS to deplete the caffeine-sensitive sarcoplasmic reticulum Ca2+ store, depolarization with 80 mM K4 in 2 mM external Ba24 caused a 100 +/- 6% increase in fura-2 fluorescence ([Ba2+]j). During the 17.5 min 0 Ca PSS recovery from depolarization, exposure to 10 microM ryanodine inhibited the removal of [Ba24]i by 69 + 3% when compared with control (0 Ca PSS without ryanodine).7. It was concluded that in bovine and porcine smooth muscle cells: (a) ryanodine (> 10 microM) releases Ca24 from the sarcoplasmic reticulum; (b) ryanodine ( 10O microM) decreases Ca24 efflux, probably by inhibition of Na+-Ca2+ exchange; (c) the sarcoplasmic reticulum Ca24 store may be larger in bovine than in porcine smooth muscle cells; thus, porcine cells have a relatively greater reliance on Ca24 influx to increase [Ca2+]i.

Development of a Carbon Nanotube-Based Micro-CT and its Applications in Preclinical Research

NASA Astrophysics Data System (ADS)

Burk, Laurel May

Due to the dependence of researchers on mouse models for the study of human disease, diagnostic tools available in the clinic must be modified for use on these much smaller subjects. In addition to high spatial resolution, cardiac and lung imaging of mice presents extreme temporal challenges, and physiological gating methods must be developed in order to image these organs without motion blur. Commercially available micro-CT imaging devices are equipped with conventional thermionic x-ray sources and have a limited temporal response and are not ideal for in vivo small animal studies. Recent development of a field-emission x-ray source with carbon nanotube (CNT) cathode in our lab presented the opportunity to create a micro-CT device well-suited for in vivo lung and cardiac imaging of murine models for human disease. The goal of this thesis work was to present such a device, to develop and refine protocols which allow high resolution in vivo imaging of free-breathing mice, and to demonstrate the use of this new imaging tool for the study many different disease models. In Chapter 1, I provide background information about x-rays, CT imaging, and small animal micro-CT. In Chapter 2, CNT-based x-ray sources are explained, and details of a micro-focus x-ray tube specialized for micro-CT imaging are presented. In Chapter 3, the first and second generation CNT micro-CT devices are characterized, and successful respiratory- and cardiac-gated live animal imaging on normal, wild-type mice is achieved. In Chapter 4, respiratory-gated imaging of mouse disease models is demonstrated, limitations to the method are discussed, and a new contactless respiration sensor is presented which addresses many of these limitations. In Chapter 5, cardiac-gated imaging of disease models is demonstrated, including studies of aortic calcification, left ventricular hypertrophy, and myocardial infarction. In Chapter 6, several methods for image and system improvement are explored, and radiation therapy-related micro-CT imaging is present. Finally, in Chapter 7 I discuss future directions for this research and for the CNT micro-CT.

SU-E-I-49: The Evaluation of Usability of Multileaf Collimator for Diagnostic Radiation in Cephalometric Exposure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, S; Kim, K; Jung, H

Purpose: This study evaluated usability of Multileaf collimator (MLC) for diagnostic radiation in cephalometric exposure using optical stimulated luminance dosimeters (OSLDs) Methods: The MLC material was made alloy tool steel (SKD-11) and the density of it is 7.89g/m3 that is similar to it of steel (Fe, 7.85 g/m3) and the MLC was attached to general radiography unit (Rex-650R, Listem Inc, Korea) for cephalometric exposure. The OSLDs that used were nanoDotTM Dosimeter (Landauer Inc, Glenwood, USA) and we read out OSLDs with micro star system (Landauer Inc, Glenwood, USA). The Optical annealing system contained fluorescent lamps (Osram lumilux, 24 W, 280more » ∼780 nm). To measure absorbed dose using OSLDs, was carried out dosimetric characteristics of OSLDs. Based on these, we evaluated dose reduction of critical organ (Eyes, Thyroids) with MLC in cephalometric exposure Results: The dosimetric characteristics were following that batch homogeneity was 1.21% and reproducibility was 0.96% of the coefficient of variation The linearity was that the correlation of between dose and count was fitted by linear function (dose,mGy = 0.00029 × Count, R2 =0.997). The range of angular dependence was from −3.6% to 3.7% variation when each degree was normalized by zero degree. The organ dose of Rt. eye, Lt eye, thyroids were 77.8 μGy, 337.0 μGy, 323.1μGy, respectively in open field and the dose reduction of organ dose was 10.6%(8.3μGy), 12.4 %(42 μGy), 87.1%(281.4μGy) with MLC Conclusion: We certified dose reduction of organ dose in cephalometric exposure. The dose reduction of Eye was 11% because of reduction of field size and it of thyroids was 87% by primary beam shielding.« less

Some inferences from in vivo experiments with metal and metal oxide nanoparticles: the pulmonary phagocytosis response, subchronic systemic toxicity and genotoxicity, regulatory proposals, searching for bioprotectors (a self-overview)

PubMed Central

Katsnelson, Boris A; Privalova, Larisa I; Sutunkova, Marina P; Gurvich, Vladimir B; Loginova, Nadezhda V; Minigalieva, Ilzira A; Kireyeva, Ekaterina P; Shur, Vladimir Y; Shishkina, Ekaterina V; Beikin, Ya B; Makeyev, Oleg H; Valamina, Irene E

2015-01-01

The purpose of this paper is to overview and summarize previously published results of our experiments on white rats exposed to either a single intratracheal instillation or repeated intraperitoneal injections of silver, gold, iron oxide, copper oxide, nickel oxide, and manganese oxide nanoparticles (NPs) in stable water suspensions without any chemical additives. Based on these results and some corroborating data of other researchers we maintain that these NPs are much more noxious on both cellular and systemic levels as compared with their 1 μm or even submicron counterparts. However, within the nanometer range the dependence of systemic toxicity on particle size is intricate and non-unique due to complex and often contra-directional relationships between the intrinsic biological aggressiveness of the specific NPs, on the one hand, and complex mechanisms that control their biokinetics, on the other. Our data testify to the high activity of the pulmonary phagocytosis of NPs deposited in airways. This fact suggests that safe levels of exposure to airborne NPs are possible in principle. However, there are no reliable foundations for establishing different permissible exposure levels for particles of different size within the nanometric range. For workroom air, such permissible exposure levels of metallic NP can be proposed at this stage, even if tentatively, based on a sufficiently conservative approach of decreasing approximately tenfold the exposure limits officially established for respective micro-scale industrial aerosols. It was shown that against the background of adequately composed combinations of some bioactive agents (comprising pectin, multivitamin-multimineral preparations, some amino acids, and omega-3 polyunsaturated fatty acid) the systemic toxicity and even genotoxicity of metallic NPs could be markedly attenuated. Therefore we believe that, along with decreasing NP-exposures, enhancing organisms’ resistance to their adverse action with the help of such bioprotectors can prove an efficient auxiliary tool of health risk management in occupations connected with them. PMID:25945048

Some inferences from in vivo experiments with metal and metal oxide nanoparticles: the pulmonary phagocytosis response, subchronic systemic toxicity and genotoxicity, regulatory proposals, searching for bioprotectors (a self-overview).

PubMed

Katsnelson, Boris A; Privalova, Larisa I; Sutunkova, Marina P; Gurvich, Vladimir B; Loginova, Nadezhda V; Minigalieva, Ilzira A; Kireyeva, Ekaterina P; Shur, Vladimir Y; Shishkina, Ekaterina V; Beikin, Ya B; Makeyev, Oleg H; Valamina, Irene E

2015-01-01

The purpose of this paper is to overview and summarize previously published results of our experiments on white rats exposed to either a single intratracheal instillation or repeated intraperitoneal injections of silver, gold, iron oxide, copper oxide, nickel oxide, and manganese oxide nanoparticles (NPs) in stable water suspensions without any chemical additives. Based on these results and some corroborating data of other researchers we maintain that these NPs are much more noxious on both cellular and systemic levels as compared with their 1 μm or even submicron counterparts. However, within the nanometer range the dependence of systemic toxicity on particle size is intricate and non-unique due to complex and often contra-directional relationships between the intrinsic biological aggressiveness of the specific NPs, on the one hand, and complex mechanisms that control their biokinetics, on the other. Our data testify to the high activity of the pulmonary phagocytosis of NPs deposited in airways. This fact suggests that safe levels of exposure to airborne NPs are possible in principle. However, there are no reliable foundations for establishing different permissible exposure levels for particles of different size within the nanometric range. For workroom air, such permissible exposure levels of metallic NP can be proposed at this stage, even if tentatively, based on a sufficiently conservative approach of decreasing approximately tenfold the exposure limits officially established for respective micro-scale industrial aerosols. It was shown that against the background of adequately composed combinations of some bioactive agents (comprising pectin, multivitamin-multimineral preparations, some amino acids, and omega-3 polyunsaturated fatty acid) the systemic toxicity and even genotoxicity of metallic NPs could be markedly attenuated. Therefore we believe that, along with decreasing NP-exposures, enhancing organisms' resistance to their adverse action with the help of such bioprotectors can prove an efficient auxiliary tool of health risk management in occupations connected with them.

Establishment of cells to monitor Microprocessor through fusion genes of microRNA and GFP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsutsui, Motomu; Hasegawa, Hitoki; Adachi, Koichi

Microprocessor, the complex of Drosha and DGCR8, promotes the processing of primary microRNA to precursor microRNA, which is a crucial step for microRNA maturation. So far, no convenient assay systems have been developed for observing this step in vivo. Here we report the establishment of highly sensitive cellular systems where we can visually monitor the function of Microprocessor. During a series of screening of transfectants with fusion genes of the EGFP cDNA and primary microRNA genes, we have obtained certain cell lines where introduction of siRNA against DGCR8 or Drosha strikingly augments GFP signals. In contrast, these cells have notmore » responded to Dicer siRNA; thus they have a unique character that GFP signals should be negatively and specifically correlated to the action of Microprocessor among biogenesis of microRNA. These cell lines can be useful tools for real-time analysis of Microprocessor action in vivo and identifying its novel modulators.« less

Non-linear macro evolution of a dc driven micro atmospheric glow discharge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, S. F.; Zhong, X. X., E-mail: xxzhong@sjtu.edu.cn

2015-10-15

We studied the macro evolution of the micro atmospheric glow discharge generated between a micro argon jet into ambient air and static water. The micro discharge behaves similarly to a complex ecosystem. Non-linear behaviors are found for the micro discharge when the water acts as a cathode, different from the discharge when water behaves as an anode. Groups of snapshots of the micro discharge formed at different discharge currents are captured by an intensified charge-coupled device with controlled exposure time, and each group consisted of 256 images taken in succession. Edge detection methods are used to identify the water surfacemore » and then the total brightness is defined by adding up the signal counts over the area of the micro discharge. Motions of the water surface at different discharge currents show that the water surface lowers increasingly rapidly when the water acts as a cathode. In contrast, the water surface lowers at a constant speed when the water behaves as an anode. The light curves are similar to logistic growth curves, suggesting that a self-inhibition process occurs in the micro discharge. Meanwhile, the total brightness increases linearly during the same time when the water acts as an anode. Discharge-water interactions cause the micro discharge to evolve. The charged particle bomb process is probably responsible for the different behaviors of the micro discharges when the water acts as cathode and anode.« less

Hair and toenail arsenic concentrations of residents living in areas with high environmental arsenic concentrations.

PubMed Central

Hinwood, Andrea L; Sim, Malcolm R; Jolley, Damien; de Klerk, Nick; Bastone, Elisa B; Gerostamoulos, Jim; Drummer, Olaf H

2003-01-01

Surface soil and groundwater in Australia have been found to contain high concentrations of arsenic. The relative importance of long-term human exposure to these sources has not been established. Several studies have investigated long-term exposure to environmental arsenic concentrations using hair and toenails as the measure of exposure. Few have compared the difference in these measures of environmental sources of exposure. In this study we aimed to investigate risk factors for elevated hair and toenail arsenic concentrations in populations exposed to a range of environmental arsenic concentrations in both drinking water and soil as well as in a control population with low arsenic concentrations in both drinking water and soil. In this study, we recruited 153 participants from areas with elevated arsenic concentrations in drinking water and residential soil, as well as a control population with no anticipated arsenic exposures. The median drinking water arsenic concentrations in the exposed population were 43.8 micro g/L (range, 16.0-73 micro g/L) and median soil arsenic concentrations were 92.0 mg/kg (range, 9.1-9,900 mg/kg). In the control group, the median drinking water arsenic concentration was below the limit of detection, and the median soil arsenic concentration was 3.3 mg/kg. Participants were categorized based on household drinking water and residential soil arsenic concentrations. The geometric mean hair arsenic concentrations were 5.52 mg/kg for the drinking water exposure group and 3.31 mg/kg for the soil exposure group. The geometric mean toenail arsenic concentrations were 21.7 mg/kg for the drinking water exposure group and 32.1 mg/kg for the high-soil exposure group. Toenail arsenic concentrations were more strongly correlated with both drinking water and soil arsenic concentrations; however, there is a strong likelihood of significant external contamination. Measures of residential exposure were better predictors of hair and toenail arsenic concentrations than were local environmental concentrations. PMID:12573904

MPGD for breast cancer prevention: a high resolution and low dose radiation medical imaging

NASA Astrophysics Data System (ADS)

Gutierrez, R. M.; Cerquera, E. A.; Mañana, G.

2012-07-01

Early detection of small calcifications in mammograms is considered the best preventive tool of breast cancer. However, existing digital mammography with relatively low radiation skin exposure has limited accessibility and insufficient spatial resolution for small calcification detection. Micro Pattern Gaseous Detectors (MPGD) and associated technologies, increasingly provide new information useful to generate images of microscopic structures and make more accessible cutting edge technology for medical imaging and many other applications. In this work we foresee and develop an application for the new information provided by a MPGD camera in the form of highly controlled images with high dynamical resolution. We present a new Super Detail Image (S-DI) that efficiently profits of this new information provided by the MPGD camera to obtain very high spatial resolution images. Therefore, the method presented in this work shows that the MPGD camera with SD-I, can produce mammograms with the necessary spatial resolution to detect microcalcifications. It would substantially increase efficiency and accessibility of screening mammography to highly improve breast cancer prevention.

Light field geometry of a Standard Plenoptic Camera.

PubMed

Hahne, Christopher; Aggoun, Amar; Haxha, Shyqyri; Velisavljevic, Vladan; Fernández, Juan Carlos Jácome

2014-11-03

The Standard Plenoptic Camera (SPC) is an innovation in photography, allowing for acquiring two-dimensional images focused at different depths, from a single exposure. Contrary to conventional cameras, the SPC consists of a micro lens array and a main lens projecting virtual lenses into object space. For the first time, the present research provides an approach to estimate the distance and depth of refocused images extracted from captures obtained by an SPC. Furthermore, estimates for the position and baseline of virtual lenses which correspond to an equivalent camera array are derived. On the basis of paraxial approximation, a ray tracing model employing linear equations has been developed and implemented using Matlab. The optics simulation tool Zemax is utilized for validation purposes. By designing a realistic SPC, experiments demonstrate that a predicted image refocusing distance at 3.5 m deviates by less than 11% from the simulation in Zemax, whereas baseline estimations indicate no significant difference. Applying the proposed methodology will enable an alternative to the traditional depth map acquisition by disparity analysis.

Assessment of mechanical rock alteration caused by CO 2 -water mixtures using indentation and scratch experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Yuhao; Aman, Michael; Espinoza, D. Nicolas

CO2 injection into geological formations disturbs the geochemical equilibrium between water and minerals. Thus, some mineral phases are prone to dissolution and precipitation with ensuing changes of petrophysical and geomechanical properties of the host formations. Chemically-assisted degradation of mechanical properties can endanger the structural integrity of the storage formation and must be carefully studied and considered to guarantee safe long-term trapping. Few experimental data sets involving CO2 alteration and mechanical testing of rock samples are available since these experiments are length, expensive, and require specialized equipment and personnel. Autoclave experiments are easier to perform and control but result in amore » limited 'skin depth' of chemically-altered zone near the surface of the sample. This article presents the validation of micro-indentation and micro-scratch tests as efficient tools to assess the alteration of mechanical properties of rocks geochemically altered by CO2-water mixtures. Results from tests on sandstone and siltstone from Crystal Geyser, Utah naturally altered by CO2-acidified water show that mechanical parameters measured with indentation (indentation hardness, Young's modulus and contact creep compliance rate) and scratching (scratch hardness and fracture toughness) consistently indicated weakening of the rock after CO2-induced alteration. Decreases of measured parameters vary from 14% to 87%. Experimental results and analyses show that micromechanical tests are potentially quick and reliable tools to determine the change of mechanical properties of rocks subject to exposure to CO2-acidified water, particularly in well-controlled autoclave experiments. Measured parameters are not intended to provide inputs for coupled reservoir simulation with geomechanics but rather to inform the execution of larger scale tests investigating the susceptibility of rock facies to chemical alteration by CO2-water mixtures. Recognizing this susceptibility of rock facies of CO2 geological storage target formations is critical to controlling undesired emergent behavior associated with CO2 sequestration.« less

A framework for measurement and harmonization of pediatric multiple sclerosis etiologic research studies: The Pediatric MS Tool-Kit.

PubMed

Magalhaes, Sandra; Banwell, Brenda; Bar-Or, Amit; Fortier, Isabel; Hanwell, Heather E; Lim, Ming; Matt, Georg E; Neuteboom, Rinze F; O'Riordan, David L; Schneider, Paul K; Pugliatti, Maura; Shatenstein, Bryna; Tansey, Catherine M; Wassmer, Evangeline; Wolfson, Christina

2018-06-01

While studying the etiology of multiple sclerosis (MS) in children has several methodological advantages over studying etiology in adults, studies are limited by small sample sizes. Using a rigorous methodological process, we developed the Pediatric MS Tool-Kit, a measurement framework that includes a minimal set of core variables to assess etiological risk factors. We solicited input from the International Pediatric MS Study Group to select three risk factors: environmental tobacco smoke (ETS) exposure, sun exposure, and vitamin D intake. To develop the Tool-Kit, we used a Delphi study involving a working group of epidemiologists, neurologists, and content experts from North America and Europe. The Tool-Kit includes six core variables to measure ETS, six to measure sun exposure, and six to measure vitamin D intake. The Tool-Kit can be accessed online ( www.maelstrom-research.org/mica/network/tool-kit ). The goals of the Tool-Kit are to enhance exposure measurement in newly designed pediatric MS studies and comparability of results across studies, and in the longer term to facilitate harmonization of studies, a methodological approach that can be used to circumvent issues of small sample sizes. We believe the Tool-Kit will prove to be a valuable resource to guide pediatric MS researchers in developing study-specific questionnaire.

Exploring the feasibility of private micro flood insurance provision in Bangladesh.

PubMed

Akter, Sonia; Brouwer, Roy; van Beukering, Pieter J H; French, Laura; Silver, Efrath; Choudhury, Saria; Aziz, Syeda Salina

2011-04-01

This paper aims to contribute to the debate on the feasibility of the provision of micro flood insurance as an effective tool for spreading disaster risks in developing countries and examines the role of the institutional-organisational framework in assisting the design and implementation of such a micro flood insurance market. In Bangladesh, a private insurance market for property damage and livelihood risk due to natural disasters does not exist. Private insurance companies are reluctant to embark on an evidently unprofitable venture. Testing two different institutional-organisational models, this research reveals that the administration costs of micro-insurance play an important part in determining the long-term viability of micro flood insurance schemes. A government-facilitated process to overcome the differences observed in this study between the nonprofit micro-credit providers and profit-oriented private insurance companies is needed, building on the particular competence each party brings to the development of a viable micro flood insurance market through a public-private partnership. © 2011 The Author(s). Disasters © Overseas Development Institute, 2011.

Design and fabrication of semi-transparent screen based on micro-patterns for direct-view type head-up display in automobiles

NASA Astrophysics Data System (ADS)

Lee, Jae-Yong; Kim, Hyo-Jun; Kim, Young-Joo

2016-02-01

A semi-transparent screen with hemisphere micro-patterns was proposed and designed to enhance the brightness uniformity of the display image toward the driver for a direct-view type head-up display. The hemisphere micro-patterns were designed to consider the inclined angle of the windshield for efficient reflection and scattering toward to the driver. The density and radius of the hemisphere micro-patterns were adjusted as a function of position on the screen based on the geometrical calculation and analyzed by the commercial optical simulation tool based on a ray-tracing method. The designed hemisphere micro-patterns was fabricated by the thermal reflow method and evaluated to confirm the uniform illumination. From the results, the semi-transparent screen with variable micro-patterns shows the 91.9 % of brightness uniformity with the enhanced luminance compare to a screen without micro-patterns. A luminance of fabricated screen also shows good agreement with the simulation result to reflect the clear and bright driving information to the driver.

Microanalysis (micro-XRF, micro-XANES, and micro-XRD) of a tertiary sediment using microfocused synchrotron radiation.

PubMed

Denecke, Melissa A; Somogyi, Andrea; Janssens, Koen; Simon, Rolf; Dardenne, Kathy; Noseck, Ulrich

2007-06-01

Micro-focused synchrotron radiation techniques to investigate actinide elements in geological samples are becoming an increasingly used tool in nuclear waste disposal research. In this article, results using mu-focus techniques are presented from a bore core section of a U-rich tertiary sediment collected from Ruprechtov, Czech Republic, a natural analog to nuclear waste repository scenarios in deep geological formations. Different methods are applied to obtain various, complementary information. Elemental and element chemical state distributions are obtained from micro-XRF measurements, oxidation states of As determined from micro-XANES, and the crystalline structure of selected regions are studied by means of micro-XRD. We find that preparation of the thin section created an As oxidation state artifact; it apparently changed the As valence in some regions of the sample. Results support our previously proposed hypothesis of the mechanism for U-enrichment in the sediment. AsFeS coating on framboid Fe nodules in the sediment reduced mobile groundwater-dissolved U(VI) to less-soluble U(IV), thereby immobilizing the uranium in the sediment.

MicroScope: a platform for microbial genome annotation and comparative genomics

PubMed Central

Vallenet, D.; Engelen, S.; Mornico, D.; Cruveiller, S.; Fleury, L.; Lajus, A.; Rouy, Z.; Roche, D.; Salvignol, G.; Scarpelli, C.; Médigue, C.

2009-01-01

The initial outcome of genome sequencing is the creation of long text strings written in a four letter alphabet. The role of in silico sequence analysis is to assist biologists in the act of associating biological knowledge with these sequences, allowing investigators to make inferences and predictions that can be tested experimentally. A wide variety of software is available to the scientific community, and can be used to identify genomic objects, before predicting their biological functions. However, only a limited number of biologically interesting features can be revealed from an isolated sequence. Comparative genomics tools, on the other hand, by bringing together the information contained in numerous genomes simultaneously, allow annotators to make inferences based on the idea that evolution and natural selection are central to the definition of all biological processes. We have developed the MicroScope platform in order to offer a web-based framework for the systematic and efficient revision of microbial genome annotation and comparative analysis (http://www.genoscope.cns.fr/agc/microscope). Starting with the description of the flow chart of the annotation processes implemented in the MicroScope pipeline, and the development of traditional and novel microbial annotation and comparative analysis tools, this article emphasizes the essential role of expert annotation as a complement of automatic annotation. Several examples illustrate the use of implemented tools for the review and curation of annotations of both new and publicly available microbial genomes within MicroScope’s rich integrated genome framework. The platform is used as a viewer in order to browse updated annotation information of available microbial genomes (more than 440 organisms to date), and in the context of new annotation projects (117 bacterial genomes). The human expertise gathered in the MicroScope database (about 280,000 independent annotations) contributes to improve the quality of microbial genome annotation, especially for genomes initially analyzed by automatic procedures alone. Database URLs: http://www.genoscope.cns.fr/agc/mage and http://www.genoscope.cns.fr/agc/microcyc PMID:20157493

MicroScope: a platform for microbial genome annotation and comparative genomics.

PubMed

Vallenet, D; Engelen, S; Mornico, D; Cruveiller, S; Fleury, L; Lajus, A; Rouy, Z; Roche, D; Salvignol, G; Scarpelli, C; Médigue, C

2009-01-01

The initial outcome of genome sequencing is the creation of long text strings written in a four letter alphabet. The role of in silico sequence analysis is to assist biologists in the act of associating biological knowledge with these sequences, allowing investigators to make inferences and predictions that can be tested experimentally. A wide variety of software is available to the scientific community, and can be used to identify genomic objects, before predicting their biological functions. However, only a limited number of biologically interesting features can be revealed from an isolated sequence. Comparative genomics tools, on the other hand, by bringing together the information contained in numerous genomes simultaneously, allow annotators to make inferences based on the idea that evolution and natural selection are central to the definition of all biological processes. We have developed the MicroScope platform in order to offer a web-based framework for the systematic and efficient revision of microbial genome annotation and comparative analysis (http://www.genoscope.cns.fr/agc/microscope). Starting with the description of the flow chart of the annotation processes implemented in the MicroScope pipeline, and the development of traditional and novel microbial annotation and comparative analysis tools, this article emphasizes the essential role of expert annotation as a complement of automatic annotation. Several examples illustrate the use of implemented tools for the review and curation of annotations of both new and publicly available microbial genomes within MicroScope's rich integrated genome framework. The platform is used as a viewer in order to browse updated annotation information of available microbial genomes (more than 440 organisms to date), and in the context of new annotation projects (117 bacterial genomes). The human expertise gathered in the MicroScope database (about 280,000 independent annotations) contributes to improve the quality of microbial genome annotation, especially for genomes initially analyzed by automatic procedures alone.Database URLs: http://www.genoscope.cns.fr/agc/mage and http://www.genoscope.cns.fr/agc/microcyc.

TREXMO: A Translation Tool to Support the Use of Regulatory Occupational Exposure Models.

PubMed

Savic, Nenad; Racordon, Dimitri; Buchs, Didier; Gasic, Bojan; Vernez, David

2016-10-01

Occupational exposure models vary significantly in their complexity, purpose, and the level of expertise required from the user. Different parameters in the same model may lead to different exposure estimates for the same exposure situation. This paper presents a tool developed to deal with this concern-TREXMO or TRanslation of EXposure MOdels. TREXMO integrates six commonly used occupational exposure models, namely, ART v.1.5, STOFFENMANAGER(®) v.5.1, ECETOC TRA v.3, MEASE v.1.02.01, EMKG-EXPO-TOOL, and EASE v.2.0. By enabling a semi-automatic translation between the parameters of these six models, TREXMO facilitates their simultaneous use. For a given exposure situation, defined by a set of parameters in one of the models, TREXMO provides the user with the most appropriate parameters to use in the other exposure models. Results showed that, once an exposure situation and parameters were set in ART, TREXMO reduced the number of possible outcomes in the other models by 1-4 orders of magnitude. The tool should manage to reduce the uncertain entry or selection of parameters in the six models, improve between-user reliability, and reduce the time required for running several models for a given exposure situation. In addition to these advantages, registrants of chemicals and authorities should benefit from more reliable exposure estimates for the risk characterization of dangerous chemicals under Regulation, Evaluation, Authorisation and restriction of CHemicals (REACH). © The Author 2016. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

GERD related micro-aspiration in chronic mustard-induced pulmonary disorder.

PubMed

Aliannejad, Rasoul; Hashemi-Bajgani, Seyed-Mehdi; Karbasi, Asharaf; Jafari, Mahvash; Aslani, Jafar; Salehi, Maryam; Ghanei, Mostafa

2012-08-01

Bronchiolitis obliterans (BO) is the main pulmonary involvement resulting from sulfur mustard (SM) gas exposure that was used against Iranian civilians and military forces during the Iran-Iraq war. The present study aimed to investigate the prevalence of gastro-esophageal reflux (GER) and gastric micro-aspiration in SM gas injured patients with chronic pulmonary diseases and recurrent episodes of exacerbations. This cross-sectional study was done at Baqiyatallah University of Medical Sciences, Tehran, Iran. Gastric micro-aspiration and GER were assessed in the enrolled patients by assessing bile acids, pepsin and trypsin in their bronchoalveolar lavage fluid. Our result showed that bile acids were found to be high in 21.4% patients, and low in 53.6% of patients. Only in 16% patients, no bile was detected in the BALF. Trypsin and pepsin were detected in BAL fluid of all patients. Most of BO patients after exposure to SM suffer GER, while none the etiologic factors of GER in post lung transplant BO are present. It would be hypothesized that GER per se could be considered as an aggregative factor for exacerbations in patients. Further studies will provide more advances to better understanding of pathophysiological mechanism regarding GER and BO and treatment.

Ductile cutting of silicon microstructures with surface inclination measurement and compensation by using a force sensor integrated single point diamond tool

NASA Astrophysics Data System (ADS)

Chen, Yuan-Liu; Cai, Yindi; Shimizu, Yuki; Ito, So; Gao, Wei; Ju, Bing-Feng

2016-02-01

This paper presents a measurement and compensation method of surface inclination for ductile cutting of silicon microstructures by using a diamond tool with a force sensor based on a four-axis ultra-precision lathe. The X- and Y-directional inclinations of a single crystal silicon workpiece with respect to the X- and Y-motion axes of the lathe slides were measured respectively by employing the diamond tool as a touch-trigger probe, in which the tool-workpiece contact is sensitively detected by monitoring the force sensor output. Based on the measurement results, fabrication of silicon microstructures can be thus carried out directly along the tilted silicon workpiece by compensating the cutting motion axis to be parallel to the silicon surface without time-consuming pre-adjustment of the surface inclination or turning of a flat surface. A diamond tool with a negative rake angle was used in the experiment for superior ductile cutting performance. The measurement precision by using the diamond tool as a touch-trigger probe was investigated. Experiments of surface inclination measurement and ultra-precision ductile cutting of a micro-pillar array and a micro-pyramid array with inclination compensation were carried out respectively to demonstrate the feasibility of the proposed method.

KENNEDY SPACE CENTER, FLA. - In KSC's Vertical Processing Facility, Louise Kleba of the Vehicle Integration Test Team (VITT) and engineer Devin Tailor of Goddard Space Flight Center examine the Pistol Grip Tool (PGT), which was designed for use by astronauts during spacewalks. The PGT is a self-contained, micro-processor controlled, battery-powered tool. It also can be used as a nonpowered ratchet wrench. The experiences of the astronauts on the first Hubble Space Telescope (HST) servicing mission led to recommendations for this smaller, more efficient tool for precision work during spacewalks. The PGT will be used on the second HST servicing mission, STS-82. Liftoff aboard Discovery is scheduled Feb. 11.

NASA Image and Video Library

1997-01-22

KENNEDY SPACE CENTER, FLA. - In KSC's Vertical Processing Facility, Louise Kleba of the Vehicle Integration Test Team (VITT) and engineer Devin Tailor of Goddard Space Flight Center examine the Pistol Grip Tool (PGT), which was designed for use by astronauts during spacewalks. The PGT is a self-contained, micro-processor controlled, battery-powered tool. It also can be used as a nonpowered ratchet wrench. The experiences of the astronauts on the first Hubble Space Telescope (HST) servicing mission led to recommendations for this smaller, more efficient tool for precision work during spacewalks. The PGT will be used on the second HST servicing mission, STS-82. Liftoff aboard Discovery is scheduled Feb. 11.

Prediction of novel pre-microRNAs with high accuracy through boosting and SVM.

PubMed

Zhang, Yuanwei; Yang, Yifan; Zhang, Huan; Jiang, Xiaohua; Xu, Bo; Xue, Yu; Cao, Yunxia; Zhai, Qian; Zhai, Yong; Xu, Mingqing; Cooke, Howard J; Shi, Qinghua

2011-05-15

High-throughput deep-sequencing technology has generated an unprecedented number of expressed short sequence reads, presenting not only an opportunity but also a challenge for prediction of novel microRNAs. To verify the existence of candidate microRNAs, we have to show that these short sequences can be processed from candidate pre-microRNAs. However, it is laborious and time consuming to verify these using existing experimental techniques. Therefore, here, we describe a new method, miRD, which is constructed using two feature selection strategies based on support vector machines (SVMs) and boosting method. It is a high-efficiency tool for novel pre-microRNA prediction with accuracy up to 94.0% among different species. miRD is implemented in PHP/PERL+MySQL+R and can be freely accessed at http://mcg.ustc.edu.cn/rpg/mird/mird.php.