Glass Syringe Research Articles

Minimizing Contamination from Plastic Labware in the Quantification of C16 and C18 Fatty Acids in Filter Samples of Atmospheric Particulate Matter and Their Utility in Apportioning Cooking Source Contribution to Urban PM2.5

Palmitic acid (C16:0) and stearic acid (C18:0) are among the most abundant products in cooking emission, and thus could serve as potential molecular tracers in estimating the contributions of cooking emission to particulate matter (PM2.5) pollution in the atmosphere. Organic tracer analysis in filter-based samples generally involves extraction by organic solvents, followed by filtration. In these procedures, disposable plastic labware is commonly used due to convenience and as a precaution against sample-to-sample cross contamination. However, we observed contamination for both C16:0 and C18:0 fatty acids, their levels reaching 6–8 ppm in method blanks and leading to their detection in 9% and 42% of PM2.5 samples from Hong Kong, indistinguishable from the blank. We present in this work the identification of plastic syringe and plastic syringe filter disc as the contamination sources. We further demonstrated that a new method procedure using glass syringe and stainless-steel syringe filter holder offers a successful solution. The new method has reduced the contamination level from 6.6 ± 1.2 to 2.6 ± 0.9 ppm for C16:0 and from 8.9 ± 2.1 to 1.9 ± 0.8 ppm for C18:0 fatty acid. Consequently, the limit of detection (LOD) for C16:0 has decreased by 57% from 1.8 to 0.8 ppm and 56% for C18:0 fatty acid from 3.2 to 1.4 ppm. Reductions in both LOD and blank variability has allowed the increase in quantification rate of the two fatty acids in ambient samples and thereby retrieving more data for estimating the contribution of cooking emission to ambient PM2.5. With the assistance of three cooking related tracers, palmitic acid (C16:0), stearic acid (C18:0) and cholesterol, positive matrix factorization analysis of a dataset of PM2.5 samples collected from urban Hong Kong resolved a cooking emission source. The results indicate that cooking was a significant local PM2.5 source, contributing to an average of 2.2 µgC/m3 (19%) to organic carbon at a busy downtown roadside location and 1.8 µgC/m3 (15%) at a general urban site.

Novel approaches for the lipid sponge phase crystallization of the Rhodobacter sphaeroides photosynthetic reaction center.

With the recent developments in the field of free-electron-laser-based serial femtosecond crystallography, the necessity to obtain a large number of high-quality crystals has emerged. In this work crystallization techniques were selected, tested and optimized for the lipid mesophase crystallization of the Rhodobacter sphaeroides membrane pigment-protein complex, known as the photosynthetic reaction center (RC). Novel approaches for lipid sponge phase crystallization in comparatively large volumes using Hamilton gas-tight glass syringes and plastic pipetting tips are described. An analysis of RC crystal structures obtained by lipid mesophase crystallization revealed non-native ligands that displaced the native electron-transfer cofactors (carotenoid sphero-idene and a ubi-quinone molecule) from their binding pockets. These ligands were identified and were found to be lipids that are major mesophase components. The selection of distinct co-crystallization conditions with the missing cofactors facilitated the restoration of sphero-idene in its binding site.

Spatial mapping of VOC exhalation by means of bronchoscopic sampling

Breath analysis holds promise for non-invasive in vivo monitoring of disease related processes. However, physiological parameters may considerably affect profiles of exhaled volatile organic substances (VOCs). Volatile substances can be released via alveoli, bronchial mucosa or from the upper airways. The aim of this study was the systematic investigation of the influence of different sampling sites in the respiratory tract on VOC concentration profiles by means of a novel experimental setup.After ethical approval, breath samples were collected from 25 patients undergoing bronchoscopy for endobronchial ultrasound or bronchoscopic lung volume reduction from different sites in the airways. All patients had total intravenous anaesthesia under pressure-controlled ventilation. If necessary, respiratory parameters were adjusted to keep PETCO2 = 35–45 mm Hg. 30 ml gas were withdrawn at six sampling sites by means of gastight glass syringes: S1 = Room air, S2 = Inspiration, S3 = Endotracheal tube, S4 = Trachea, S5 = Right B6 segment, S6 = Left B6 segment (S4–S6 through the bronchoscope channel). 10 ml were used for VOC analysis, 20 ml for PCO2 determination. Samples were preconcentrated by solid-phase micro-extraction (SPME) and analysed by gas chromatography–mass spectrometry (GC-MS). PCO2 was determined in a conventional blood gas analyser.Statistically significant differences in substance concentrations for acetone, isoprene, 2-methyl-pentane and n-hexane could be observed between different sampling sites. Increasing substance concentrations were determined for acetone (15.3%), 2-methyl-pentane (11.4%) and n-hexane (19.3%) when passing from distal to proximal sampling sites. In contrast, isoprene concentrations decreased by 9.9% from proximal to more distal sampling sites. Blank bronchoscope measurements did not show any contaminations.Increased substance concentrations in the proximal respiratory tract may be explained through substance excretion from bronchial mucosa while decreased concentrations could result from absorption or reaction processes. Spatial mapping of VOC profiles can provide novel insights into substance specific exhalation kinetics and mechanisms.

PARTICULATE MATTER FROM SYRINGES USED FOR INTRAVITREAL INJECTIONS.

Syringes containing anti-vascular endothelial growth factor drugs to treat retinal diseases are prepared in different ways by various parties with syringe selection, preparation, and storage conditions affecting the risk of injecting particles into the vitreous. This study examines particle loads from various syringes over time. Four syringes were studied: two plastic transfer syringes lubricated with silicone oil or oleamide, a glass syringe with baked-on silicone, and a lubricant-free polymer syringe. Syringes were rinsed with water or filled with buffer and analyzed over time; particles were quantified by flow imaging. Particle formation in a bevacizumab formulation was also characterized. Insulin syringes consistently showed very high particle counts. Oleamide-lubricated syringes had substantially fewer particles, but showed appreciable increases over time (leading to visible particles). Baked-on silicone glass syringes and lubricant-free polymer syringes both showed low particle levels ≥10 μm. Lubricant-free syringes showed the lowest particle levels ≥1 μm and the lowest particle levels with bevacizumab agitation. Syringes have different intrinsic particle loads which can contribute to particle loads in the delivered drug. Oleamide-lubricated transfer syringes, commonly used for bevacizumab repackaging, have time-dependent particle loads and are associated with the formation of visible particles beyond 30 days of storage.

Microextraction on a screw for determination of trace amounts of hexanal and heptanal as lung cancer biomarkers

Solid phase microextraction on a screw was utilized for the extraction of hexanal and heptanal as lung cancer biomarkers from urine samples. Reduced graphene oxide (rGO) was coated on the surface of a stainless-steel set screw by electrophoretic deposition method. The screw was located inside a glass cover, and the created channel acted as the sample solution flow pass. A 5 mL glass syringe was connected to a syringe pump to direct the sample and the eluent through the channel. The extraction procedure was followed by gas chromatography/mass spectrometry (GC/MS) for separation and determination of the extracted aldehydes. The effective parameters on the extraction efficiencies of the analytes were identified and optimized. Under the optimal extraction conditions, the extraction time was as short as 10 min. The calibration curves indicated good linearity (R2 > 0.97) within the concentration range of 1.0−50 μg L−1. The obtained limits of detection (LODs) for hexanal and heptanal were down to 0.4 and 0.3 μg L−1, respectively. Considering the repeatability, simplicity, and eco-friendliness of this simple extraction method, it can be efficiently used for preconcentration of aldehydes in different samples.

In vitro fermentation of fodder beet root increases cumulative gas production of methane and carbon dioxide.

The relationship between proportion of fodder beet root (FB: Beta vulgaris subsp. vulgaris L.) in a perennial ryegrass (Lolium perenne) diet and gas production was investigated in vitro. Cumulative gas production and fermentation products were measured in calibrated glass syringes using a factorial arrangement (4 x 6), of dry matter proportion of FB (0, 15, 35 and 50% DM: 0FB, 15FB, 35FB and 50FB, respectively), and incubation time (0, 2, 4, 8, 12 and 24 h). Concentrations of methane (CH4) and carbon dioxide (CO2) produced both in fermentation and from bicarbonate buffering of volatile fatty acid, were also calculated. The proportion of FB root linearly increased volume of gas (mL) produced per g dry matter (DM) and per g organic matter (OM) with gas accumulation 14.8% greater for 50FB compared to 0FB at 24-hours of incubation (P<0.001). The concentration of propionic and butyric acids also increased relative to the proportion of FB (P < 0.001). Stoichiometric calculations indicate that FB increased CO2 released from both buffering and fermentation processes but reduced the fractions of methane in gas (17.6, 17.4, 17.0 and 16.8 ± 0.4% for 0FB, 15FB, 35FB, and 50FB, respectively, P< 0.001). However, the greater OM content of FB increased the total volume of both CO2 and CH4 produced. Results suggest that FB altered the thermodynamics of fermentation early in digestion by increasing formation of propionate which acted as a hydrogen sink to reduce formation of methane. However, as fermentation progressed, butyrate forming pathways became more favourable. The greater OM content of FB compared to ryegrass increased absolute volumes of CO2 and CH4 from fermentation, resulting in greater emission of gasses per kg DM of substrate. Further investigation in vivo is required to determine potential effects of microbial protein synthesis on gas production and further verify these results.

Reducing Ruminal Ammonia Production With Improvement in Feed Utilization Efficiency and Performance of Murrah Buffalo (Bubalus bubalis) Through Dietary Supplementation of Plant-Based Feed Additive Blend.

The study evaluated the potential of blends of eucalyptus oil and aqueous extract of mulethi (root of Glycyrrhiza glabra) to reduce rate of ruminal ammonia production without affecting feed digestion to improve nitrogen utilization efficiency and performance of Murrah buffalo (Bubalus bubalis). Based on preliminary independent studies with graded doses of eucalyptus oil and mulethi root aqueous extract in modulating in vitro rumen fermentation, four blends of feed additive comprising graded doses (5, 10, 15, and 25 μL) of eucalyptus oil and a fixed quantity (15 μL) of aqueous extract of mulethi roots were prepared and examined for their effects on in vitro rumen fermentation and on methane and gas production in 100-mL calibrated glass syringes by standard IVGP protocol. Rumen liquor was collected from four rumen fistulated Murrah buffaloes fed a total mixed ration. Out of four blends, blend-1 comprising 5 μL of eucalyptus oil and 15 μL of aqueous extract (233.6 g/L DW) of mulethi per 40 mL of in vitro medium was found to reduce ammonia production significantly (p < 0.001) without affecting feed digestibility. An equivalent dose of blend-1 (10.5 mL of eucalyptus oil and 7.35 g of mulethi root powder/h/day) fed to four rumen fistulated buffaloes for 24 days resulted in 50% reduction (p < 0.05) in rumen ammonia level with no inhibition in feed fermentation or short-chain fatty acid production. The total bacterial population including Ruminococcus albus, Fibrobacter succinogenes, Butyrivibrio fibrisolvens, and Megasphaera elsdenii as well as anaerobic fungi and methanogenic archaea remained unaffected (p > 0.05). Twelve buffalo calves (avg. BW 137.5 ± 9.2 kg, 8–12 months old) divided into two groups of six each and fed a total mixed ration (concentrate: roughage; 60:40) with or without supplementation of blend-1 for about 3 months demonstrated 14% increase (p < 0.05) in average daily gain in BW with a trend (p < 0.10) in improvement of feed or protein utilization efficiency (1.4 vs. 1.1 g crude protein/g average daily gain; 21.4% increase). Thus, supplementation of eucalyptus oil–mulethi root blend could reduce ruminal ammonia production and improve feed utilization efficiency in ruminants.

User experience for manual injection of 2 mL viscous solutions is enhanced by a new prefillable syringe with a staked 8 mm ultra-thin wall needle

ABSTRACT Objectives User experience was compared between a new pre-fillable 2.25 mL glass syringe equipped with an ultra-thin-wall (UTW) 8 mm staked needle and a marketed BD Neopak™ syringe equipped with a special-thin-wall (STW) 12.7 mm staked needle. Methods Participants simulated subcutaneous injections with both syringes alone (formative Human Factors study) and in combination with a needlestick-prevention device (validation Human Factors study). Results Usability results of both studies showed higher success rates for delivering the full dose of 2 mL viscous solution (30 cP) with the 8mmUTW syringe than with the 12.7mmSTW one (63% vs. 42% in the formative study). The use of the 8mmUTW syringe demonstrated also better ease of use and acceptance results and 72% of formative study participants preferred this new syringe over the current one when delivering the viscous solution. Using a shorter needle also showed a benefit in decreasing the injection-related anxiety. Besides, in the case of a non-recommended injection technique, the calculated risk of accidental intramuscular injection is reduced by 2 to 13 times with the 8mmUTW syringe. Conclusion Altogether, the results obtained demonstrated an improvement of the user experience with this new syringe compared to the current one in the manual delivery of 2 mL viscous solutions.

Application of a modified lighter than water organic solvent-based air-assisted liquid–liquid microextraction method for the efficient extraction of aflatoxin M1 in unpasteurized milk samples

ABSTRACT An efficient analytical method has been developed for the extraction and quantification of aflatoxin M1 in milk samples using a modified air-assisted liquid-liquid microextraction method combined with high-performance liquid chromatography-fluorescence detector. Firstly, defatted milk is transferred into a glass test tube and its proteins are participated with zinc acetate solution. After vortexing and centrifugation of the mixture, the obtained supernatant is removed and transferred into a conical bottom glass test tube. Then, the adsorbed analyte onto the precipitated proteins is eluted with acetonitrile and after centrifugation, the eluant is mixed with the supernatant obtained from the previous step. A few microlitres of toluene (as an extraction solvent) is added into the solution and the mixture is sucked into a glass syringe and pushed out in the tube for four times. The obtained cloudy solution is centrifuged to collect the extraction solvent. Then, the lower aqueous phase is withdrawn by a glass syringe to transfer the extraction solvent to the conical section of the tube. The method was validated and under optimal conditions, it was found that the method has low limits of detection (0.9 ng L−1) and quantification (3 ng L–1), good linearity (r2 = 0.9976), and satisfactory repeatability (relative standard deviation ≤9% for intra- (n = 8) and inter-day (n = 6) precisions). The extraction recovery and enrichment factor of AFM1 were 87% and 87, respectively. Finally, the proposed method was applied on different milk samples and concentration of aflatoxin M1 was determined in the studied samples.

Hepatitis C virus genotypes and associated risk factors in the state of Pará, Northern Brazil

BackgroundDespite the emergence of more effective therapies, hepatitis C virus (HCV) infection remains a serious public health problem at the global level. Currently, this virus is classified into seven genotypes and 67 subgenotypes, which in turn are distributed heterogeneously in Brazil and worldwide. Studies have shown that this genetic divergence results in differences in the progression of chronic disease associated with HCV infection and its treatment. ObjectiveThe aim of this study was to report the frequency of HCV genotypes in the state of Pará, Northern Brazil, and to assess the association between genotype and different clinical and laboratory characteristics, as well as risk factors for infection. MethodData from 85 medical records of untreated patients who had chronic hepatitis C infection were analyzed; the patients were evaluated at two hospitals in Belem, Pará, Brazil. ResultsCirculation of genotypes 1 and 3 was detected, with a higher prevalence of genotype 1 (75.3%) than genotype 3 (24.7%). In addition, there was a predominance of subgenotype 1b (60.34%) compared to 1a (20.69%) and 3a (18.97%). Reuse of needles and/or glass syringes was significantly associated with infection by HCV genotype 1 than genotype 3; however, the small number of patients infected with genotype 3 may have biased the results. No associations between genotype and the evaluated clinical and laboratory characteristics were observed. ConclusionThis study reinforces the differences in the distribution of HCV genotypes in Brazil and showed no association between HCV genotype and progression of chronic hepatitis C in the studied group.

Modular, cost-effective, and portable capillary gradient liquid chromatography system for on-site analysis.

This work demonstrates the development of a compact, modular, cost-effective separation system configured to address a specific separation problem. The principles of the separation are based on gradient capillary liquid chromatography where the system consists of precision stepper motor-driven portable syringe pumps with interchangeable glass syringes (100 µL to 1000 µL). Excellent flow-rate precision of < 1% RSD was achieved with typical flow-rates ranging from 1 µL/min to 100 µL/min, which was ideal for capillary columns. A variable external loop volume and electrically actuated miniature injection valve was used for sample introduction. Detection was based upon a commercial Z-type UV absorbance flow-cell housed within a custom-built cooling enclosure (40mm x 40mm) which also contained a UV-LED light-source and a photodiode. System and chromatographic performance was evaluated using linear gradient elution, with day to day repeatability of <1.5% RSD (n=6) for peak area, and < 0.4% RSD (n=6) for retention time, for the separation of a 5 component mixture using a 50mm X 530µm ID C18 3µm particle capillary column. The system can run any commercial or in-house packed columns from 50mm to 100mm length with IDs ranging from 200 to 700µm. The developed portable system was operated using custom-built windows-based chromatography software, complete with data acquisition and system control.

Origin of Ubiquitous Stripes at the Graphite-Water Interface.

The investigation of solid-liquid interfaces is pivotal for understanding processes like wetting, corrosion, and mineral dissolution and growth. The graphite-water interface constitutes a prime example for studying the water structure at a seemingly hydrophobic surface. Surprisingly, in a large number of atomic force microscopy (AFM) experiments, well-ordered stripes have been observed at the graphite-water interface. Although many groups have reported on the observation of stripes at this interface, fundamental properties and, in particular, the origin of the stripes are still under debate. Proposed origins include contamination, interplanar stacking of graphene layers, formation of methanol-water nanostructures, and adsorption of nitrogen molecules. Especially, the latter interpretation has received considerable attention because of its potential impact on explaining the long-range nature of the hydrophobic interaction. In this study, we demonstrate that these stripes readily form when using standard plastic syringes to insert the water into the AFM instrument. In contrast, when clean glass syringes are used instead, no such stripes form even though nitrogen was present. We, therefore, conclude that contaminations from the plastic syringe rather than nitrogen constitute the origin of the stripes we observe. We provide high-resolution AFM data that reveal detailed structural insights into the arrangement of the stripes. The rich variability of our data suggests that the stripes might be composed of several different chemical species. Still, we cannot rule out that the stripes observed in the literature might originate from other sources; our study offers a rather straightforward explanation for the origin of the stripes. In the view of these results, we propose to carefully reconsider former assignments.

Disrupt, innovate, and transform in the era of COVID‐19

Today we live at an inflection point. For many, it's a world where things change at amazing speeds, from a patient's clinical status to a global position on risk mitigation. And it's this rate of change that has caught us either unprepared or unaware. While this notion of speed is far from new, in today's context, this speed is being defined by the emergence of COVID-19. Instant gratification is becoming less about gratification and more about a new normal driven by social and clinical necessity. Thus, I want what I when when i want it (IWWIWWIWI) may become a new clinical abbreviation that competes with the good old PRN. In this case, it's I want what I want when I want it. Perhaps we can even extend this from I want to I need. Some clinicians may remember the early days of arterial blood gas testing. The puncture of the radial artery with glass syringe, the bag of ice, and the rapid trip to the laboratory in the basement of the hospital defined an element of both technological sophistication and foot speed. Today, the glass syringe and quick footwork has, in many instances, been replaced by technology. But the story is much richer than a simple advancement of technology. This transformation has moved beyond just this blood test to the new reality of patient and consumer empowerment. Pulse oximetry has become the domain of both the physician and the consumer. Yes, I can check my oxygen partial pressure while I'm typing on my keyboard. Technology is becoming less an option and more of an imperative. From robotic microsurgery to artificial intelligence used to read chest x-rays, traditionally human tasks are being supported--if not replaced--by technological advances. Technology now offers us the opportunity to enhance many aspects of clinical practice from physical agility to cognitive function. As technology and artificial intelligence advance, the burden of many aspects of care can shift, freeing up the clinician for a higher and richer level of patient engagement. The heavy cognitive lifting of medicine may very well be transformed from medical school and on up revealing a new dynamic that facilitates adaptive thinking versus that conventional element of bookish memorization. Innovation and technology are now part and parcel of the practice of medicine. In many ways, has made us more human and these advantages extend to everyday tasks. Technology allows us to expand the richness of life to experience more sights, sounds, thoughts, and perhaps other senses that we have not even discovered. And it's these same advances that will allow medicine to evolve the personal relationship that exists between clinician and patient, and even the relationship between clinician and technology itself. And these profound changes, driven by technological advances, that create a new and richer reality, expanding our perceptions and introducing new sensory and computational skills to our human armamentarium. At the heart of our technological revolution are data. Some may argue that data are the new oil or even the new currency. But it might be better to consider data as a fundamental window into humanity. Just as the telescope and the microscope provided a new and eye-opening view of the universe, data will allow us to see vast connectivity and complexity that can define humanity. One simple comparison to today's COVID-19 pandemic and we can quickly see how the role of data allows us to tackle this disease. From bench science to social distancing, data are our best shot to understand and mitigate this disease. Yet the tsunami of information is simply beyond the comprehension of any human, even that uber-human in the white coat. The solution is not to work harder but to work smarter, and shift the burden to technology and AI. When the shift happens, another magical event will emerge to the surprise of clinicians and patients alike,the rise of empathy and engagement. Clinical senses—partnered with human sensory activity—will allow clinicians to touch with robotic exactness, see with electronic lens clarity, hear with digital fidelity, and listen with exacting sensitivity. What emerges is nothing even close to robotic but the advancement and extension of human capability. Today's technology dynamic forces the clinician to engage with a computer screen with their backs turned to the patient. Tomorrow's reality is that technology will drive aspects of care, like the physical exam, or peering into a microscope, and allow physicians to discover a richer and deeper relationship with medicine and mankind. And it's this realization that allows us to discover that innovation and technology aren't our masters, but tools to enhance our skills and improve care. In the final analysis, innovation is infectious and there is no cure.

Impacts of rumen fluid, refrigerated or reconstituted from a refrigerated pellet, on gas production measured at 24h of fermentation

Rumen fluid is used as fresh inoculum for gas production fermentations to predict the nutritional value of feeds and rations for ruminants. However, collection of rumen fluid from animal donors is invasive, expensive, time consuming and results in fluids of variable quality. The general aim was to identify a procedure to manipulate rumen inoculum in order to facilitate its storage and transfer between laboratories. This strategy would also limit fluid collections from animals. Two experiments were completed based on gas production from graduated 100 mL glass syringe with five feeds as substrates.In experiment 1, the gas production and some fermentation parameters of fresh rumen fluids were compared with those preserved at 4 °C for 24, 48, 72 and 96 h. Refrigeration did not modify concentration of volatile fatty acids and pH, but ammonia in liquids refrigerated for 48–96 h was higher (P < 0.05) compared to fresh. In contrast, rumen fluid refrigeration for 24, 48 or 72 h did not depress gas production at 24 h, but it was lower at 96 h. In experiment 2, the rumen fluid was centrifugated at 13,000 x g and sedimented material (i.e., pellet) was refrigerated for 48 h at 4 °C. The asymptote of gas production kinetics from rumen fluid regenerated from the pellet was 8 % lower (P < 0.05) than that from fresh. However for 24 h gas production, the correlation between fresh liquid and pellet inoculum, calculated for five ingredients, was high (R2 = 0.94). Results support the use of rumen fluid preserved by refrigeration for up to 72 h, and rumen fluid reconstituted from refrigerated pellet, as an alternative to fresh. This would reduce the need for laboratories to maintain animal donors and/or frequently collect rumen fluid.

Efficacy of Sunflower Oil in Modulating Rumen Functions and Reducing Enteric Methane Production in Buffalo (Bubalus bubalis)

Enteric methane emission from ruminant livestock reduces the efficiency of feed energy utilization and contributes to global warming. An experiment was conducted to investigate the effects of sunflower (SFL) oil supplementation on methanogenesis, volatile fatty acids composition and feed fermentation pattern by in vitro gas production (IVGP) test. SFL oil was examined at three concentrations (0, 0.4 and 0.8 ml/ 30 ml buffered rumen fluid). In vitro incubation was carried out with sorghum hay (200 ± 5 mg) as substrate in 100 ml calibrated glass syringes following standard IVGP protocol. Addition of SFL oil resulted in increase (p &lt; 0.05) in total gas production and decrease (p &lt; 0.05) in methane concentration in head space gas, irrespective of level of inclusion. Linear decrease (p &lt; 0.001) in feed degradability was evident with increasing doses of oil. Acetate production decreased (p &lt; 0.05) without affecting propionate, however, butyrate production increased (p &lt; 0.05) with addition of oil, irrespective of doses. The ratio of acetate to propionate was reduced (p &lt; 0.01) with addition of oils. It is concluded that sunflower oil supplementation exerted inhibitory effects on methane production; however, dry matter degradability was also reduced. Further studies need to be carried out with lower dose levels for their practical application in animal feeding practices.

Highly Selective and Sensitive Trimethylamine Gas Sensors Using Patterned Metal Oxide Nanofibers Prepared By Near-Field Electrospinning

Introduction Oxide nanofibers consisting of nanoparticles are excellent nanostructures for designing high performance gas sensors. To date, randomly tangled oxide nanofiber networks prepared by far-field electrospinning process (FFES) have been widely explored as the sensing materials. When the distance between spinneret needle and substrate is very short, the straight configuration of nanofibers can be directly written on the substrate without whipping. This is referred as near-field electrospinning (NFES), which can be applied to well-defined patterning of one-dimensional nanofibers for various new applications such as sensors, optoelectronic circuits, and functional nanoelectronics. The patterning of polymeric nanofibers has been demonstrated over a decade ago. In contrast, the fabrication of one-dimensional (1D) metal oxide nanopatterns remains challenging because it becomes difficult to control the chaotic whipping motion of the jet due to the acceleration of metal ions under the electric field. In the present study, grids, diamonds, and hexagrams composed of In2O3, Co3O4, and NiO nanofibers were prepared by NFES and their potential applications as gas sensors were investigated. The sensor using In2O3 nanofiber pattern exhibited an unprecedentedly high response (resistance ratio = 239) to 5 ppm trimethylamine (TMA) with negligible cross-responses to ubiquitous ethanol and other interference gases. Method Transparent solution containing 7 g of methanol (99 %), polyvinylpyrrolidone (PVP, 17.4 wt%, Mw = 1,300,000) and metal nitrates (indium nitrate hydrate, 1.4 wt%, 99.999%; cobalt nitrate hexahydrate, 1.7 wt%, 99.99%; nickel nitrate hexahydrate, 1.7 wt%, 99.99%) were stirred for 24 h at room temperature. The prepared clear solution was transferred to a glass syringe (1000 μL) with a 21-gauge needle, and electrospun onto a 4-inch Si/SiO2 wafer containing 76 sensor substrates (size: 1 × 1 cm2) in which Pt interdigitated electrodes (electrode width: 50 μm, electrode spacing: 5 μm) above a metallic collector. The flow rate is fixed as 0.005 μL min−1 at an applied voltage of 50 V and the distance between the tip and the collector is 1 mm. During electrospinning, the loader and collector moved toward x- and/or y-axis at a controlled moving velocity of 800 mm s−1, leading to the fabrication of precursor fiber patterns, for example, grids, diamonds, and hexagrams. The precursor patterns were annealed at 600 °C for 5 h in an air atmosphere, and converted into the corresponding patterns of In2O3, Co3O4, and NiO pattern sensors, respectively. The sensors were placed in a quartz tube furnace and heated at sensing temperature (In2O3: 350 °C; Co3O4: 225 °C; NiO: 300 °C). The dc-probe resistance of the sensor was measured using an electrometer interfaced with a computer. Results and Conclusions The well-defined patterns of continuous and cylindrical oxide nanofibers could be prepared by using highly volatile solvent (methanol) and by controlling the viscosity and electrical conductivity of spray solution, the distance between spinneret needle and substrate, and the moving velocity of spinneret needle. All the parameters had an optimum window, indicating that the sophisticated control or tuning of the parameters is essential to prepare well-organized and continuous precursor and/or metal oxide fibers via NFES. It is worthwhile to note that the longstanding problem of preparing elaborate nano-architectures consisting of 1D metal oxides has been solved for the first time by investigating the interrelations of the solution/working parameters in NFES systematically. Interestingly, the sensor using In2O3 nanofiber pattern on Pt electrodes exhibited unprecedented high selectivity and responses to TMA compared with other metal oxide nanostructures reported in the literature, whereas random networks of In2O3 nanofibers and dense thin In2O3 film with negligible Pt electrode exposure showed low response and selectivity to TMA. The intriguing trimethylamine sensing characteristics are explained in relation to the promotion of gas sensing reaction by catalytic Pt electrode, which is supported again by the high TMA selectivity of the sensors using the patterns of Co3O4 and NiO nanofibers. In addition, the highly increased sensitivity to analyte gases compared with thin film sensors can be attributed by the increased gas accessibility due to the sensor structures, which is composed of mono-layered In2O3 nanofibers with 200 nm diameter. The NFES-assisted patterning of metal oxide nanofibers can provide a new platform to design high performance gas sensors for a range of emerging applications.

Characterization of non-oxygenates hydrocarbon product from the catalytic pyrolysis of rice straw

The usage of fossil fuel as petrochemical feedstock becomes problems due to the depletion of its supply coupled with the issue of global warming and air pollution, thus a new alternative is needed. Lignocellulose biomass can be converted into hydrocarbons for the petrochemical industry’s feedstock through pyrolysis process, which is a thermal decomposition of biomass in an oxygen-free condition. The materials used in this experimental study consist of rice straw as the main feedstock, ZSM-5 as the catalyst. Rice straw is lignocellulose biomass that has the potential in Indonesia because of its abundant supply in many locations. Biomass catalytic pyrolysis was carried out using a fixed bed reactor with the varied ratios of ZSM-5 and biomass mixture and the products in the form of gaseous phase come out from the bottom of the reactor by flowing it into a glass test tube with a diameter of 2.5 cm. Pyrolysis process was carried out at temperature variations of 450°C, 500°C, and 550°C in a nitrogen gas flowing condition of 10-20 ml/minute. To detect the non-oxygenate hydrocarbon products, the sampling of the gas product was done by taken it using the glass syringe in the reactor bottom. The gas analysis was performed using Gas Chromatography-Mass Spectroscopy (GC-MS) and the calibration curve was then prepared to quantify the results by GC-MS analysis for various pyrolysis vapor compounds with their respective peak areas. With the variation of pyrolysis temperature, this study shows that the olefin group produced in catalytic pyrolysis neither does the conventional pyrolysis. But the pyrolysis produced the paraffin group in any type of pyrolysis condition process. This study also found that olefin group production was decreased in the longer time of stream reaction, while the aromatic group was increased. Generally, the amount of aromatic compound formation depends on catalyst ratio.

Syringe Pump Created using 3D Printing Technology and Arduino Platform

An open-source syringe pump has been developed for use in the analytical laboratory. Most pump parts are made on a 3D printer. Other parts (lead screw, guide rods, stepper motor, bearings, electronic components) are purchased in specialized stores. The control panel is based on the Arduino UNO. Device interaction, any settings changes, and operating mode selection are carried out using the LCD Keypad Shield (no computer connection required). The program for the microcontroller is written in Arduino IDE. Assembling the syringe pump takes several hours and requires almost no soldering. Universal clamp allows installing any syringe with a diameter of 6 to 25 mm. The syringe pump can both infuse the liquid and refill the empty syringe. To evaluate the analytical characteristics, a 10-mL glass syringe (Kloehn) was used. The dispensed volume was 1 and 5 mL. The systematic error was less than 0.1%, and the random one was less than 3 μL. Project files are available at: http://www.mass-spec.ru/projects/diy/syringe_pump/eng/.

Mechanistic and ecotoxicological studies of amoxicillin removal through anaerobic degradation systems

Many studies have been conducted on the evaluation and monitoring of micropollutants and by-products in wastewater treatment plants. Considering the increase in the production and consumption of emerging contaminants, such as drugs, personal care products, and plasticisers, it is necessary to conduct studies that support the elaboration of laws and regulations that promote the environmentally sustainable use of sludge and effluents. In this work, the biological degradation of amoxicillin was studied under two anaerobic conditions: i) using a 6L reactor operated under semi-continuous flow; and ii) a batch system with 100mL sealed glass syringes. According to the statistical analysis, amoxicillin was completely removed from the systems, but biogas production inhibition was observed (p<0.05). Liquid chromatography-high-resolution mass spectrometry analysis identified amoxicillin penicilloic acid, amoxilloic acid, amoxicillin diketopiperazine and phenol hydroxypyrazine as by-products under anaerobic conditions. Ecotoxicity tests on effluent treated under the batch conditions showed that the addition of higher amounts of amoxicillin inhibited the target species Aliivibrio fischeri and Raphidocelis subcaptata, causing functional decreases of 28.5% and 22.2% when the antibiotic concentration was 2500μgL-1. A. fischeri was the most sensitive organism to effluent treated under semi-continuous flow conditions; a continuous reduction in bioluminescence of up to 88.8% was observed after 39 days of feeding, which was associated with by-products accumulation due to unbalanced conditions during anaerobic digestion. Changes in the physico-chemical characteristics of the effluent caused the accumulation and removal of AMX-DKP IV and modified the toxicity to Lactuca sativa and R. subcapitata.

Experimental testing for metrological traceability and accuracy of liquid microflows and microfluidics

Micro-flows are growing more important and useful for a wide variety of scientific and engineering fields such as bioanalysis, drug development and administration, Organ-on-a-Chip, etc, but accurate and reliable measurements traceable to the International System of Units can be challenging in micro-to-femto flow operating ranges. In this paper a gravimetric method has been used to quantify the measurement error of the volumetric flow rate of water from 1000 μL/h to 1 μL/h delivered by a syringe pump in different experimental conditions that replicate the current microfluidics setups. Several sources of error have been determined such as the mass measurement, the fluid evaporation dependent on the gravimetric methodology implemented and the repeatability, believed to be closely related to the operating mode of the stepper motor and drive screw pitch of the syringe pump. The elastic deformability of the medical grade 1 mL polypropylene syringes commonly used in micro-flows has greatly affected the volumetric flow rate, unlike the glass syringes tested. Finally, testing the gravimetric method while adding PDMS microfluidic channels to the flow circuit served to demonstrate that material, dimensions and shape of the microchannels did not show significant influence on the volumetric flow rate error for the flow rates imposed, important to establish well defined methodologies for microfluidics.