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PubMed2006

Strength improvement of critical-sized three dimensional printing parts by infiltration of solvent-free visible light-cured resin.

The use of light-cured acrylate resin as an infiltrant can enhance flexural modulus and flexural strength of natural polymers based three dimensional printing (3DP) parts to be closed to general use of polymethyl methacrylate resin. It was observed that flexural properties of infiltrated specimens were influenced by infiltration conditions. Curing by normal halogen light bulb was more practical for critical-sized 3DP parts than curing by typically small probe of dental visible light curing unit (VLC). Similar levels of flexural properties were obtained from these two methods. Post-heated treatment after curing was also observed to further increase the flexural modulus and strength of infiltrated samples. However, flexural strain at break was not affected by different curing conditions. Preliminary In Vitro toxicity test of infiltrated 3DP parts showed that the cells which were in contact with samples were healthy. No inhibition zone was observed.

Acrylic Resins↗
PubMed1991

Exposure of 1,1,1-trichloroethane and dose-related excretion of metabolites in urine of printing workers.

The quantitative relationship between the time-weighted average exposure by inhalation to 1,1,1-trichloroethane and excretion of metabolites in urine at the end of a work shift was investigated in 48 male printing workers exposed to the solvent at levels below 65 ppm. Male control subjects, 10 in all, were also investigated. Statistical analysis showed that there is a linear relationship between the two exposure indicators, suggesting that occupational exposure to 1,1,1-trichloroethane can be bio-monitored by means of urinalysis for either total trichloro-compounds or trichloroacetic acid. The correlation coefficient was higher for total trichloro-compounds (r = 0.86-0.89 depending on correction for urine density) than trichloroacetic acid (r = 0.50-0.71), which suggests that the former is a better indicator of exposure to 1,1,1-trichloroethane than the latter. The calculations based on the present study suggest that, at the end of the shift, only less than 2% of 1,1,1-trichloroethane absorbed will be excreted as metabolites in urine.

Air Pollutants, Occupational↗
PubMed2005

Rapid detection of ssDNA and RNA using multi-walled carbon nanotubes modified screen-printed carbon electrode.

A method for rapid sensitive detection of DNA or RNA was designed using a composite screen-printed carbon electrode modified with multi-walled carbon nanotubes (MWNTs). MWNTs showed catalytic characteristics for the direct electrochemical oxidation of guanine or adenine residues of signal strand DNA (ssDNA) and adenine residues of RNA, leading to indicator-free detection of ssDNA and RNA concentrations. With an accumulation time of 5 min, the proposed method could be used for detection of calf thymus ssDNA ranging from 17.0 to 345 microg ml(-1) with a detection limit of 2.0 microg ml(-1) at 3 sigma and yeast tRNA ranging from 8.2 microg ml(-1) to 4.1 mg ml(-1). AC impedance was employed to characterize the surface of modified electrodes. The advantages of convenient fabrication, low-cost detection, short analysis time and combination with nanotechnology for increasing the sensitivity made the subject worthy of special emphasis in the research programs and sources of new commercial products.

Biocompatible Materials↗
PubMed2006

Screen-printed bienzymatic sensor based on sol-gel immobilized Nippostrongylusbrasiliensis acetylcholinesterase and a cytochrome P450 BM-3 (CYP102-A1) mutant.

Here, we describe the development of a bi-enzymatic biosensor that simplifies the sample pretreatment steps for insecticide detection, and opens the way for a highly sensitive detection of phosphorothionates in food. These compounds evolve their inhibitory activity towards acetylcholinesterases (AChEs) only after oxidation, which is performed in vivo by P450 monooxygenases. Consequently, phosphorothionates require a suitable sample pretreatment by selective oxidation to be detectable in AChE based systems. In this study, enzymatic phosphorothionate activation and AChE inhibition were integrated in a single biosensor unit. A triple mutant of cytochrome P450 BM-3 (CYP 102-A1) and Nippostrongylus brasiliensis AChE (NbAChE) was immobilized using a fluoride catalyzed sol-gel process. Different sol-gel types were fabricated and characterized regarding enzyme loading capacity and enzyme activity containment. The enzyme sol-gel itself already proved to be suitable for the highly sensitive detection of paraoxon and parathion in a spectrometric assay. A method for screen-printing of this enzyme sol-gel on thick film electrodes was developed. Finally, amperometric biosensors containing coimmobilized NbAChE and the cytochrome P450 BM-3 mutant were produced and characterized with respect to signal stability, organophosphate detection, and storage stability. The detection limits achieved were 1 microg/L for paraoxon and 10 microg/L for parathion, which is according to EC regulations the highest tolerable pesticide concentration in infant food.

Acetylcholinesterase↗
PubMed2004

Enzymatic versus chemical deinking of non-impact ink printed paper.

Enzymatic versus chemical deinking is examined for MOW and photocopy prints. Several enzymatic preparations and two fibre/ink particle separation methods are tested. Deinking was monitored by image analysis and standard pulp and paper characterisation procedures. The effectiveness of the fibre/ink particle separation method depends on the ink particle's size: for smaller particles a washing step is recommended whereas for larger particles, the use of flotation is necessary. The enzymatic treatment is a competitive alternative for MOW and photocopy paper deinking. However, the process requires the selection of an adequate enzymatic preparation for each paper grade.

Biodegradation, Environmental↗
PubMed2003

Ink-jet printing for micropattern generation of laminin for neuronal adhesion.

In order to achieve defined adhesion and neurite outgrowth, the growth substrate must be patterned in an appropriate way. We utilised ink-jet printing by means of a piezo-based microdispenser to create defined line patterns of a polymer with typical dimensions of 100 microm width on glass, silicon, gold and carbon substrates. Vinnapas, a co-polymer of vinyl acetate and ethylene, was mixed with the extracellular matrix protein laminin to achieve neuronal adhesion on the surface of the patterns. It could be demonstrated that the laminin entrapped in the polymer lines can be recognised by a specific antibody. Adhesion of embryonic chicken forebrain neurones is following the prepared lines, and identity of adhering cells could be shown by neurofilament staining. These findings open the route for the generation of complex small neuronal arrays and for the electrochemical investigation of the obtained neuronal matrix.

Animals↗
PubMedDate not supplied

The role of zeolites in wastewater treatment of printing inks.

The adsorption of residual organic pollutants from flocculated printing ink wastewater onto several synthetic zeolites was investigated as a finishing method for additional reduction of TOC. The nonselective removal of total organic content was studied. The amount of adsorbed organics was largest for ZSM-5 and NH4-Beta while the other zeolites studied showed lower efficiency, suggesting that adsorption is independent of pore structure. The adsorption rates of organic pollutants were fast. Although the TOC removal increases with increasing amount of zeolite, because of the necessity of additional filtration to lower turbidity to required levels, 5.0 g/L of zeolite was found to be optimum. The 88% reduction of TOC obtained with a single flocculation treatment was improved with the combination of flocculation and adsorption with ZSM-5 which resulted in the overall TOC efficiency of 95%. The addition of zeolites in decantated supernatant water, obtained after flocculation, was also studied in order to assess the effect of floc on zeolite capacity. A decrease in adsorption capacity occurred only if a coagulant concentration less than optimal was applied. Removal efficiency then decreased by around 10%. It was concluded that flocculation followed by adsorption with zeolites is an effective treatment method for this kind of wastewater.

Adsorption↗
PubMed2003

Spatial-frequency spectra of printed characters and human visual perception.

It is well known that certain spatial frequency (SF) bands are more important than others for character recognition. Solomon and Pelli [Nature 369 (1994) 395-397] have concluded that human pattern recognition mechanism is able to use only a narrow band from available SF spectrum of letters. However, the SF spectra of letters themselves have not been studied carefully. Here I report the results of an analysis of SF spectra of printed characters and discuss their relationship to the observed band-pass nature of letter recognition.

Humans↗
PubMed2002

Metabolite ratio of toluene-exposed rotogravure printing plant workers reflects individual mutagenic risk by sister chromatid exchanges.

The study involved a group of 42 printing plant workers and a control group of 45 blood donors. At the working places, the ambient air-toluene concentration amounted from 141 to 328 mg/m(3). Sister chromatid exchanges (SCEs) were significantly elevated by three units in the exposed group. In this group, the concentration of urinary toluene metabolites was also considerably increased-hippuric acid was four times higher and the o-cresol and p-cresol fractions were twice as high. Results of toluene monitoring of ambient air- or blood-toluene concentrations did not show any relationships with individual SCE. While these SCE values revealed only a weak relationship with the corresponding hippuric acid data, a significant correlation with the cresols, which are known to be more genotoxic than hippuric acid, appeared in highly exposed workers. An attempt was made to consider the individual metabolic balance of toluene excretion products. For that reason individual cresol to hippuric acid ratios were calculated and related to corresponding SCE values. In all investigated subpopulations of the exposed group, this ratio correlated with SCE at a level of high significance. This strong interrelationship is a powerful argument for the genotoxic behavior of toluene. Furthermore, the individual metabolic balance, as a consequence of genetic polymorphism, should be considered in the discussion about genetic risk of toluene.

Adult↗
PubMed2002

Biodegradation of VOCs from printing press air by an on-site pilot plant bioscrubber and laboratory scale continuous yeast cultures.

The volatile organic compound composition (VOCs) of printing press air was found to contain mostly ethanol, but also ethyl acetate, 1-propanol, 2-propanol, 1-methoxy-2-propanol and 3-ethoxy-1-propanol. A pilot plant bioscrubber inoculated with a mixed microbial population was constructed on-site. The bioscrubber was able to treat the polluted gas efficiently. It, however, suffered from strong wall growth and blockages in the column. The efficiencies of the pilot plant and a bioreactor is compared. The yeasts Candida guilliermondii and Saccharomyces cerevisiae known to tolerate ethanol were selected instead of mixed population to avoid the wall growth a nd blockages inthe bioreactor. The removal of the VOCs both individually and as a complex mixture was tested in a microcultivation system and in continuous chemostat cultures with and without cell recycling. The Candida yeast could use all the compounds as a carbon source while growth of S. cerevisiae was markedly slower on the methoxylated and ethoxylated propanols. Best total removal of the VOCs was 99% and achieved by C. guilliermondii. The only compound that was not totally removable in the chemostat experiment with C. guilliermondii was 1-methoxy-2-propanol. In laboratory scale the total and volumetric removal of VOCs by C. guilliermondii was more efficient compared to the pilot plant encouraging to scale up and applying the yeast bioreactor to real field conditions.

Air Pollutants, Occupational↗
PubMed2005

The assembly of phonology from print is serial and subject to strategic control: evidence from serbian.

The Serbian writing system was used to investigate whether a serial procedure is implicated in print-to-sound translation and whether components of the reading aloud system can be strategically controlled. In mixed- and pure-alphabet lists, participants read aloud phonologically bivalent words comprising bivalent letters in initial or final positions. Words with bivalent letters in initial positions were disadvantaged relative to nonbivalent controls to a greater degree than were words with bivalent letters in final positions, and the size of the effect was greater in the mixed-alphabet situations than it was in the pure-alphabet situations. A dual-route theory of bialphabetic reading aloud is proposed in which the nonlexical procedure operates serially and nonlexical spelling-sound correspondences for each script can be strategically emphasized or deemphasized.

Fixation, Ocular↗
PubMed2000

1,6-hexanediol diacrylate: a rapid and potent sensitizer in the printing industry.

Printers are exposed to a wide variety of irritants and sensitizers. Allergy developing from a single exposure to any compound is rare. We report two cases of workers in the printing industry who developed allergic contact dermatitis to 1,6-hexanediol diacrylate (HDDA) within a short period of exposure. The first developed within weeks of exposure to a plastic sheet primed with HDDA. The second developed after a single accidental exposure.

Accidents, Occupational↗
PubMed2002

Operating the production calculus: ordering a production system in the print industry.

The topic of shop-floor work has been extensively examined within sociology. However, the organizational structures within which this work takes place have, in the most part, been taken as unexamined givens. Yet, their operation is also the shop-floor work of some people. This paper examines the way in which the stable organizational structures within which shop-floor work takes place are achieved. It is based upon a fieldwork investigation of a large commercial printer and focuses upon the collaborative work of those who are involved in scheduling the production of a job and their use of 'the production calculus' in planning the work of the site. The print industry is undergoing considerable technological change and scheduling technologies have been developed to automate this work. However, there has been little take up of these technologies and the paper also considers how the characteristics of operating the production calculus in practice may account for this.

Humans↗
PubMed1999

The control of press cleaning solvent vapors in a small lithographic printing establishment.

Small businesses frequently have inadequate in-house expertise to solve a variety of safety and health problems. The National Institute for Occupational Safety and Health (NIOSH) has therefore conducted a demonstration project in the commercial lithographic printing industry, which consists largely of small companies, in an effort to establish suitable control technology for airborne solvent vapors released primarily during press cleaning operations. These solvent vapors have a number of potential adverse health effects, including narcosis, kidney and liver damage, and cancer. Also, airborne anti-offset powder is a potential allergic sensitizer and cause of occupational asthma. As a means of controlling worker exposures to the vapors and dust, a local exhaust inlet was attached to the side of the press adjacent to the paper delivery point. Tempered outside air was introduced through ceiling outlets installed to make up for the exhausted air. Measurements of press operator exposure and area concentrations of solvent vapors and area concentration of anti-offset powder were made before and after installation of the new ventilation controls. Vapor concentrations were reduced by 73 percent for the press operators. Area concentrations of the vapors were reduced by 86 percent and dust concentration by 67 percent. The ventilation system was found to be suitable for vapor and dust control, although substitution of a cleaning solution containing non-carcinogenic solvents for solutions containing carcinogens was recommended.

Air Pollutants, Occupational↗
PubMed1988

The influence of task and location on solvent exposures in a printing plant.

A work measurement technique was used to monitor the activities of seven printing press operators. Repeated observations were made to learn workers' tasks and workers' locations in the plant, and a photoionization detector was used to measure the instantaneous solvent concentration in each worker's breathing zone. Location data, analyzed using a computer aided design system, did not show any indication that there were high or low exposure areas. Regression, however, showed that a significant amount of variability in a worker's exposures was accounted for by the number of times the worker performed a certain "hazardous task" (r2 = 0.57). The results indicate that it may be possible to simplify industrial hygiene sampling strategies by using work measurement data, such as time study or work sampling, to identify maximum risk employees.

Air Pollutants, Occupational↗
PubMed2016

A synergistic approach to the design, fabrication and evaluation of 3D printed micro and nano featured scaffolds for vascularized bone tissue repair.

3D bioprinting has begun to show great promise in advancing the development of functional tissue/organ replacements. However, to realize the true potential of 3D bioprinted tissues for clinical use requires the fabrication of an interconnected and effective vascular network. Solving this challenge is critical, as human tissue relies on an adequate network of blood vessels to transport oxygen, nutrients, other chemicals, biological factors and waste, in and out of the tissue. Here, we have successfully designed and printed a series of novel 3D bone scaffolds with both bone formation supporting structures and highly interconnected 3D microvascular mimicking channels, for efficient and enhanced osteogenic bone regeneration as well as vascular cell growth. Using a chemical functionalization process, we have conjugated our samples with nano hydroxyapatite (nHA), for the creation of novel micro and nano featured devices for vascularized bone growth. We evaluated our scaffolds with mechanical testing, hydrodynamic measurements and in vitro human mesenchymal stem cell (hMSC) adhesion (4 h), proliferation (1, 3 and 5 d) and osteogenic differentiation (1, 2 and 3 weeks). These tests confirmed bone-like physical properties and vascular-like flow profiles, as well as demonstrated enhanced hMSC adhesion, proliferation and osteogenic differentiation. Additional in vitro experiments with human umbilical vein endothelial cells also demonstrated improved vascular cell growth, migration and organization on micro-nano featured scaffolds.

Bone Regeneration↗
PubMed1993

A fast graphics printing program for neurophysiological data.

A program was written in assembly language for fast graphics screen dump of neurophysiological data during and after experiments. This program takes approximately 3 s to plot a 1024 x 768 graphics image. A resident program has also been produced, which allows a screen graphics image to be printed by using a keyboard command. A Pascal-compatible object file is available to interface the program with Turbo-Pascal programs.

Computer Graphics↗
PubMed1998

The prevalence of work-related upper limb disorders in a printing factory.

The association between problems of the upper limb and the workplace is complex. A large printing manufacturer in the North West of England sought the advice of both a surgeon, specializing in problems of the upper limb and an ergonomist in an attempt to control the frequency of these abnormalities amongst its workforce. The prevalence of these problems prior to and after the introduction of a number of recommendations was collated and the results are discussed. Effectively the introduction of sensible and sympathetic modifications to the workplace appeared to reduce the number of upper limb disorders.

Adult↗