Cleaning Step Research Articles

Low temperature hydrogen plasma permeation in palladium and its alloys for fuel recycling in fusion systems

Superpermeation of hydrogen isotopes through metal foils is a critical component for efficient fuel recycling in fusion power systems. In that context hydrogen permeation through foils of palladium and its alloys with silver and copper was studied at low temperature (60 - 200°C) under plasma exposure. These alloys differ significantly in both bulk and surface properties, and comparisons can provide mechanistic insights. Permeation was observed only during plasma operation, confirming the negligible contribution of molecular hydrogen to the observed flux. As-received foils required surface treatment to achieve top performance. For Pd and Pd75Ag25 an oxidation treatment increased permeation an order of magnitude, but proved unstable as this desirable surface was reduced under hydrogen plasma exposure. In contrast, an Ar plasma cleaning step provided both high and stable flux. As-received FCC phase Pd60Cu40 foils required annealing to transform it into the high permeability BCC phase that delivered top performance. All foils displayed similar temperature dependence with flux declining with temperature, suggesting that the primary rate-limiting step is absorption of superthermal hydrogen. Among these foils the hydrogen flux through PdCu was 3 - 5X greater than that of Pd or PdAg, which were similar. The superiority of BCC PdCu is attributed to its superior hydrogen desorption kinetics. Using PdCu 100% permeation of supplied hydrogen was achieved, and the flux saturated with increasing plasma power at values >10−2 mol H·m−2·s−1, and under these conditions permeation rates are equivalent with or without the membrane present. The fluxes achieved are the highest reported to date at these conditions, and the results highlight the important roles of both surface and bulk properties.

Conductive organic electrodes for flexible electronic devices

The paper reports on a novel process flow to manufacture conductive organic electrodes from highly conductive doped PEDOT:PSS polymer films that can be patterned and display a good adhesion to oxidized Si wafers as well as to flexible substrates, such as Mylar. Among other results, it is shown that multiple depositions of PEDOT:PSS increase the electrical conductivity by more than two orders of magnitude without increasing the film thickness of PEDOT:PSS significantly. An exponential dependence between sheet resistance and the number of PEDOT:PSS coatings has been found. The electrical conductivity of PEDOT:PSS can be increased by another two orders of magnitude doping with Cu nanoparticles when coated on the surface of a soft-baked PEDOT:PSS film. It is found, however, that both kinds of conductivity enhancement are not additive. Adhesion of PEDOT:PSS to oxidized Si wafers and BoPET (Mylar) has been ensured by applying an oxygen plasma cleaning step before spin coating. The manufactured high-conductivity PEDOT:PSS film can be patterned using a sacrificial metal layer with subsequent etching of PEDOT:PSS in oxygen plasma, followed by the removal of the patterned segments of the sacrificial metal layer in an aqueous acid solution.

Sustainable solvent metal lift-off for compound semiconductor fabrication with improved manufacturability

Due to concerns regarding substrate damage, wet photoresist removal has been adopted over dry etch techniques for certain metal lift-off processes on substrates and metals that are susceptible to plasma damage. Wet photoresist removal generally requires the use of polar aprotic solvents and historically n-methyl pyrrolidone (NMP) has been broadly adopted. A successful lift-off process requires consideration of both the solvent used to remove the photoresist as well as the correct photoresist retrograde profile. As features become smaller and more critical, the overall photoresist profile becomes more challenging. The use of bottom anti-reflective coatings (BARC) has become necessary to better control the reflected light and minimize potential defectivity during patterning. However, addition of the BARC layer complicates the resist removal process by requiring a secondary cleaning step since wet photoresist strip chemistries, such as NMP, generally do not remove it. There have been several developmental efforts in the metal lift-off industry to formulate a solvent, which could remove both photoresist and BARC, concurrently. In the first half of this paper, various wet photoresist removers are compared to determine the most effective wet resist strip for removal of both photoresist and BARC in one step. The second half of the paper summarizes two different metal liftoff processes and compares the performance of the best chemistry from initial experimentation, Technistrip® MLO-07, to NMP.

Assessment of the Hygienic Practices and Microbial Quality of Broiler Meat and its Contact Surfaces From Poultry Retail Outlet and Cold Room in Rivers State Nigeria

Poor hygiene and sanitary practices among poultry meat sellers can lead to the contamination of meat. This contamination can occur as a result of contamination from the contact surfaces in the cold room and retail outlet. The aim of the present study was to assess the sanitary quality of Broiler meat and its contact surfaces (apron, butcher hand, butcher table, bowl, butcher knife and weighing scale) in cold room and retail outlet. Swab samples were assessed for total bacteria count, total coliform count, total staphylococcus count and total fungal counts using Standard Microbiology methods. Mean Total viable count of each sample ranged from Log 10 cfu/cm2/g 3.64 to7.94 and 3.14 to 4.75 from the retail outlets and Cold-room respectively. Mean Total Staphylococcus count. of each sample ranged from Log 10 cfu/cm2/g 1.67to 4.67 and 2.01 to 3.87 from the retail outlets and Cold-room respectively. Counts from the retail outlets were significantly higher than counts in the cold room. Organisms isolated included ; Staphylococcus sp, Bacillus sp, Escherichia coli, Proteus sp, Salmonella sp, Aeromonas sp, Pseudomonas sp, Klebsiella sp and Enterobacter sp. Fungi isolated was Aspergillus sp, Saccharomyces sp, Penicillium sp and Rhodotorula sp. Antibiogram was carried out on the isolated organisms it was observed that Klebsiella sp and Enterobacter sp were resistant to most of the antibiotics used. In order to prevent cross-contamination of meat with isolated bacteria, appropriate cleaning and sanitization steps are required. According to the study, meat contact surfaces that were not thoroughly cleaned before usage, could function as a source of cross contamination. It is recommended that meat sellers especially in developing countries need proper education and training on good hygiene practice. Regulating agencies are also advised to ensure strict compliance by meat sellers to safety standards by embarking on routine inspection at retail outlets and market places.

EXPERIMENTAL INVESTIGATION OF OXYFUEL COMBUSTION OF RDF AND WOOD CHIPS IN A GRATE INCINERATION SYSTEM

Combustion experiments of dried wood chips and refuse derived fuel (RDF) under air and oxyfuel conditions have been performed in an extendedly modified 240 kW<sub>Th</sub> pilot-scale grate incineration facility with forward acting grate. To get insight into differences of the combustion processes between air and oxyfuel operation the concentrations of the main flue-gas species have been measured at the end of the combustion chamber and throughout the furnace. Additionally, the temperature has been measured inside the grate bars and the fuel bed as well as along the flue-gas pathway. It could be demonstrated that oxyfuel combustion of wood chips leads to stable CO<sub>2</sub> concentrations in the dry flue gas above 80 vol. %. During oxyfuel combustion of RDF similar trends have been observed; however, the combustion has shown significant fluctuations due to fuel-feeding issues. Profile measurements revealed a spatially extended reaction zone in the oxyfuel cases compared to the respective air combustion cases but with decreasing differences towards the end of the combustion zone. Wet flue-gas recycling has been applied to the experimental system which led to significantly higher H<sub>2</sub>O concentrations in the furnace during oxyfuel operation. Concentrations of CO, NO, SO<sub>2</sub>, and HCl in the flue gas have been increased during oxyfuel combustion. Especially during RDF oxyfuel combustion the concentration of HCl and SO<sub>2</sub> in the flue gas has been very high. In such a case it would be necessary to recycle the flue gas after appropriate cleaning steps. Also, considering the significantly lower flue-gas volume flow towards the atmosphere absolute emissions seem to be manageable.

Optimization of chemical mechanical polishing of (010) β-Ga2O3

Smooth (< 0.5 nm rms) and subsurface damage-free (010) β-Ga2O3 was achieved with low-pressure chemical mechanical polishing. An applied pressure of 1 kPa along with colloidal silica and poromeric polyurethane polishing pads rotating at 30 rpm was found to be the optimal polishing parameters for (010) β-Ga2O3. Using higher pressures typically employed in the current literature induced subsurface damage in the substrates. Diffuse scatter intensity of triple-axis x-ray rocking curves was used to determine the presence of subsurface lattice damage, which was quantified by measuring peak widths below the half maximum (i.e., FWXM where X < 0.5). The initially rough surfaces of (010) β-Ga2O3 substrates due to wafer slicing and grinding were lapped and polished. A 5 μm Al2O3 slurry followed by a 0.3 μm Al2O3 slurry was used as the primary lap material removal step. The material removal rates were ∼20 and ∼9 μm/h, respectively. Then, chemical mechanical polishing was performed using colloidal alumina followed by colloidal silica. The removal rates were ∼1.3 and ∼0.4 μm/h, respectively. Only colloidal silica showed the complete removal of subsurface damage. The final (020) β-Ga2O3 rocking curve FWHM was ∼13″ and FW(0.001)M was ∼120″, which matches the widths of commercially available pristine (010) β-Ga2O3. A final cleaning step using dilute bleach and dilute citric acid to remove residual silica slurry particles from the surface was demonstrated.

A probabilistic study on hole cleaning optimization

Hole cleaning is considered as one of the most important drilling fluid functions. An efficient hole cleaning ensures a reliable well drilling practice with minimum troublesome problems. In this study, two main steps of hole cleaning, i.e., cuttings removal from under the bit and cuttings transport to the surface are discussed based on the drilling data of a shale formation. The traditional models for optimization of each step are presented. As the models require variety of input data, which are usually subjected to some extent of errors and uncertainties, the output of the model is also an uncertain parameter. Using Monte Carlo simulation, a simple probabilistic study was conducted to quantify the certainty level of the obtained results. Based on the result of this study, it is shown that for the proposed well, a good hole cleaning is expected. However, a more reliable decision for further hole cleaning optimization should be made considering the results of uncertainty analysis.

Eleven quick tips for data cleaning and feature engineering.

Applying computational statistics or machine learning methods to data is a key component of many scientific studies, in any field, but alone might not be sufficient to generate robust and reliable outcomes and results. Before applying any discovery method, preprocessing steps are necessary to prepare the data to the computational analysis. In this framework, data cleaning and feature engineering are key pillars of any scientific study involving data analysis and that should be adequately designed and performed since the first phases of the project. We call "feature" a variable describing a particular trait of a person or an observation, recorded usually as a column in a dataset. Even if pivotal, these data cleaning and feature engineering steps sometimes are done poorly or inefficiently, especially by beginners and unexperienced researchers. For this reason, we propose here our quick tips for data cleaning and feature engineering on how to carry out these important preprocessing steps correctly avoiding common mistakes and pitfalls. Although we designed these guidelines with bioinformatics and health informatics scenarios in mind, we believe they can more in general be applied to any scientific area. We therefore target these guidelines to any researcher or practitioners wanting to perform data cleaning or feature engineering. We believe our simple recommendations can help researchers and scholars perform better computational analyses that can lead, in turn, to more solid outcomes and more reliable discoveries.

Design and Implementation of COVID-19 Data Analysis and Visualization System

In order to facilitate the real-time analysis of COVID-19, a COVID-19 data analysis and visualization system is designed and implemented, which acuqries data from Baidu epidemic platform. It displays the epidemic dynamics, new trends, cumulative diagnosis, diagnosis distribution and other information through a big visualization screen. This system adopts the front-end and back-end separation technology, uses Scrapy to acquire epidemic data, and stores the data in the MySQL database through cleaning, conversion and other steps. The back-end obtains data based on Spring Boot, and the front-end uses Vue technology to analyze the back-end data and display the epidemic data in ECharts diversified charts. The practice under the production environment proves that the system can meet the requirements of real-time display and has high scalability.

Polystyrene Sulfonate Particles as Building Blocks for Nanofiltration Membranes.

Today the standard treatment for wastewater is secondary treatment. This procedure cannot remove salinity or some organic micropollutants from water. In the future, a tertiary cleaning step may be required. An attractive solution is membrane processes, especially nanofiltration (NF). However, currently available NF membranes strongly reject multivalent ions, mainly due to the dielectric effect. In this work, we present a new method for preparing NF membranes, which contain negatively and positively charged domains, obtained by the combination of two polyelectrolytes with opposite charge. The negatively charged polyelectrolyte is provided in the form of particles (polystyrene sulfonate (PSSA), d ~300 nm). As a positively charged polyelectrolyte, polyethyleneimine (PEI) is used. Both buildings blocks and glycerol diglycidyl ether as crosslinker for PEI are applied to an UF membrane support in a simple one-step coating process. The membrane charge (zeta potential) and salt rejection can be adjusted using the particle concentration in the coating solution/dispersion that determine the selective layer composition. The approach reported here leads to NF membranes with a selectivity that may be controlled by a different mechanism compared to state-of-the-art membranes.

A 3-D Printed Helix for Traveling-Wave Tubes

In this work, a 3-D printed copper helix for a traveling-wave tube (TWT) is reported. The fabricated helix was designed to be used in a TWT operating at millimeter-wave frequencies (60–80 GHz). The helix was realized with an additive micromanufacturing technique ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> AM). Measurements were also performed to estimate the losses of the printed material and evaluate the RF performance of deposited copper. Simulations showed that a TWT based on the 3-D printed helix can have a gain of about 30 dB at 66 GHz and a 1-dB bandwidth of about 5 GHz. The estimated losses from RF measurements reveal an RF copper conductivity of about <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 10^{{7}}$ </tex-math></inline-formula> S/m, measured in air without any surface cleaning steps, which is a very good value and comparable to bulk copper conductivity in the millimeter-wave range.

Molecular beam homoepitaxy of N-polar AlN on bulk AlN substrates

N-polar AlN epilayers were grown on the N-face of single-crystal bulk AlN substrates by plasma-assisted molecular beam epitaxy. A combination of in situ thermal deoxidation and Al-assisted thermal desorption at high temperature aided in removing native surface oxides and impurities from the N-polar surface of the substrate enabling successful homoepitaxy. Subsequent epitaxial growth of the AlN layer on the in situ cleaned substrates, grown in a sufficiently high Al droplet regime, exhibited smooth surface morphologies with clean and wide atomic steps. KOH etch studies confirmed the N-polarity of the homoepitaxial films. Secondary ion mass spectrometry profiles show Si and H impurity concentrations below the noise levels, whereas O and C impurity concentrations of ∼8×1017 and ∼2×1017 atoms/cm3 are observed, respectively. Although the structural defect densities are low, they interestingly appear as inversion domains of different dimensionalities.

Numerical Study of Temperature Evolution During Friction Element Welding

Abstract Welding of dissimilar materials is critical in industries where mixed materials with high strength-to-weight ratios are urgently needed. Friction element welding (FEW) is a promising solution, with the ability to join high strength materials for a wide range of thicknesses with low input energy and a short processing time. However, the temperature evolution and the influence of different processing parameters remain unclear. To bridge this knowledge gap, this work develops a coupled thermal–mechanical finite element model to study the FEW process. The simulation results agree well with the experimental measurements of material deformation and transient temperature evolution. It is found that the friction element’s rotational speed has the greatest impact on friction heat generation, followed by the processing times for different steps. The aluminum layer is heated during the penetration and cleaning steps, thus a lower rotational speed during the penetration step can help prevent the aluminum layer from undesired overheating. The steel layer and the friction element are mainly heated during the cleaning and welding steps. The strong heating, potentially melting, will be beneficial to the friction element’s plastic deformation and bond formation. To enhance the heating of the steel layer and the friction element, faster rotational speeds or longer processing periods could be employed during the cleaning and welding steps. The results by this study establish the relationship between processing conditions and the temperature evolution of different parts, which will guide the design and optimization of the FEW technique for various applications.

THE EFFECTIVENESS OF USING TOOTHPASTE CONTAINING ROBUSTA COFFEE BEAN EXTRACT IN INHIBITING THE FORMATION OF DENTAL PLAQUE

Background: Periodontal disease is caused by the interaction between pathogenic bacteria and plaque, without the accumulation of plaque, periodontal disease will not appear. Plaque will be visible one to two days if no oral cleaning steps are taken. The combination of antimicrobial therapy such as antibiotics and mouthwash as well as mechanical therapy such as scaling and root plain gives more effective results. However, if done in the long term it will cause resistance. To overcome this, alternative materials are needed that are used to inhibit bacterial growth, one of which is robusta coffee beans. The content of robusta coffee bean extract contains phenolic and flavonoid compounds that function as antibacterials that work by disrupting the function of the cytoplasmic and cytoplasmic membranes of bacteria. Method: In this study, 6 groups were used, namely KN, K-, K+, KP 25%, KP 50%, and KP 75%. The gingivitis model was made with wire using ligation technique for 3 days, then toothpaste was applied, brushing process, and disclosing agent was given, and the plaque index calculation was PHP (Personal Hygiene Performance). The data obtained were then analyzed using the Kruskall-Wallis test followed by the Mann-Whitney test. Result: The Robusta coffee bean extract toothpaste group at a concentration of 75% experienced a significant reduction in plaque compared to the negative control group and the 25% treatment group (p&lt;0.05), but there were no significant differences or had the same ability when compared to the experimental group. 50% treatment group, normal control group and positive control group. Conclusion: The 75% concentration of Robusta coffee bean extract found in toothpaste is proven to be effective in inhibiting the formation of dental plaque.

Oxidation of pyrite during barite extraction

Marine barite is widely considered a reliable recorder of sulfur and oxygen isotope compositions of seawater sulfate. The traditional barite extraction method involves multiple oxidative cleaning steps to sequentially remove other minerals from sediments and additional purification steps to remove residual insoluble O-bearing minerals like rutile. During these processes pyrite is likely oxidized, thereby introducing sulfur from pyrite and oxygen from water and/or air to sulfate. We systematically investigate the effects of pyrite oxidation during barite extraction using two sets of synthetic marine sediments spiked with varying amounts of pyrite. One is subjected to acid-based leaching and Na2CO3-based purification, while the other is only treated with Na2CO3. Our results show a negative correlation between the pyrite-to-barite mass ratio and the apparent S- and O-isotope values of extracted barite. The difference in S-isotope ratios between two sample sets suggests that acid leaching with subsequent Na2CO3 purification results in the conversion of approximately 9% of the added pyrite to barite, whereas purification alone converts about 4.8% of the added pyrite. Based on these findings, we estimate that for marine sediments with a pyrite-to-barite ratio lower than 3 wt% and an S-isotope difference smaller than 50‰ between marine barite and sedimentary pyrite, the S-isotope offset imparted by pyrite oxidation during sequential leaching is within a 0.3‰ error.

Hydrophobic Films Surface Preparation And Its Impact On Wet Cleaning

Keywords: hydrophobic films, drying marks, SiCN, amorphous carbon, chemical oxide growthIntroduction Integrated circuits manufacturing requires use of hydrophobic materials, as low-k films. Maintaining their integrity during wet cleaning is challenging. Indeed, the aqueous liquid film break-up on these surfaces during the cleaning process can result in undesired drying marks defects [1] which can cause open-circuits and be yield killers by blocking proper patterning. Use of dry-cleaning methods instead of wet chemistries can be a solution to avoid drying marks formation. However, while relevant in particle removal they cannot remove chemisorbed defects. Therefore, the use of aqueous solutions cannot be always avoided to clean hydrophobic films. In this case, inducing surface modification of the hydrophobic surface before the aqueous-cleaning step can be a solution. Since drying is carried out after the surface becomes hydrophilic, the occurrence of drying marks can be prevented.In this work we first study how chemical treatments can modify hydrophobic surfaces, so they get a hydrophilic nature. Based on that, we evaluate the interest that can have such step before aqueous wafer cleaning techniques.Experimental and characterizationsSilicon carbon nitrogen (SiCN) and amorphous carbon (a-C) films are deposited by plasma enhanced chemical vapor deposition method on 300mm p-type (011) silicon substrate. The a-C composition is of 65% carbon,35% hydrogen while the SiCN composition is of: 42% Hydrogen, 20% carbon, 14% nitrogen, 24% silicon. They have been obtained with elastic recoil detection analysis, nuclear reaction analysis and Rutherford backscattering spectroscopy. All wet chemical surface preparations have been carried out on spin dry single wafer platforms from SCREEN. Two wet chemistries have been evaluated: Standard Clean 1 (mix of ammonia, hydrogen peroxide and water with a respective volume ratio of 1/2/80, fresh chemistry at 65°C) and ozonated water (20ppm). A treatment with an excimer ultraviolet lamp with a 172nm wavelength has been also done.The reactions between these films and treatments are characterized by AR-XPS and XRR.Artificial contamination of SiCN wafers for particle removal tests has been done by spin-drying using isopropanol containing monodisperse SiO2 particles of 80nm.Results and discussionThe surface preparations of a-C and SiCN films impact the water contact angles, as reported in Figure 1.A-C surface presents a contact angle of 5° with water, after UV or ozonated water treatments, while stays unaltered with the SC1. This difference between the ozonated water and SC1 dispense can be related to the oxidizing power difference as ozonated water features higher redox potential than ammonia. Proposed mechanism of amorphous carbon oxidation by ozone is the breaking of C=C bonds and the formation of carboxyl —COOH groups [2].On the other hand, SiCN contact angle is reduced by SC1, ozonated water and UV (respectively 45, 30 and 5°). AR-XPS characterizations have been used to identify the bonds modification during these treatments. The results lead to the conclusion of an oxidation mechanism for ozonated water, with an oxide layer thickness of less than 5nm (XRR) (Table 1). SiCN bonds oxidation are thermodynamically favored, even though kinetics of these reactions has not been studied (Table 2).The development of a hydrophilic behavior on these surfaces suggests that we avoid watermarks formations. A comparison of SC1 spray cleaning on modified and as deposited SiCN wafers has been carried, to determine the impact of surface modification on particle removal efficiency.Nevertheless, in the specific case of low-k films two potential impacts of these surface modifications also need to be investigated. Indeed, electrical properties of low-k films are key parameters, that is why the consequences of surface modification on them need to be evaluated. And delamination of low-k interfaces is already a failure risk. It would be enhanced by an adhesion strength reduction due to surface energy change. Contact angle measurements and the Fowkes model have been used to deduce the influence of these treatments on surface energy.ConclusionThe cleaning of hydrophobic films is a key challenge for yield benefits. These films are prone to drying marks formation during aqueous cleaning steps. In this work, we study how surface preparation can break non-polar bonds, leading to the development of a hydrophilic surface. Several treatments (UV, SC1 and ozonated water) and materials (a-C, SiCN) have been studied. A comparison of particle removal efficiency with SC1 spray method between as deposited and modified films have been carried out, to quantify the impact of these modifications on wet surface cleaning.

Productivity, cost and product quality of complete-tree processing in orchard termination operations

To minimize the burden on periodical orchard termination and renewal, complete tree removal and processing represent the most effective work technique, when the above- and below-ground tree portions are kept together and removed in one single action. However, the presence of rootstocks imposes specific biomass processing techniques, when turning the removals into wood fuel. In particular, one needs to use a comminuting machine that can cope with soild contamination and introduce a cleaning step to remove soil particles from the feedstock. The goal of this research was to determine if one can efficiently process complete trees arising from orchard termination conducted as an integrated single-pass operation. The processing system under testing consisted of a commercial set-up commonly used when producing compost at recycle yards and was obtained by coupling a slow-speed shredder with a rotary sieve in an on-line arrangement. Productivity levels were quite stable, varying between 17 and 24 tPMH−1. Total system cost was 304 € per scheduled machine hour (SMH) and processing cost ranged from 18 to 25 €t−1. 82% of the input material ended into the fuelwood stream, which still contained some residual contamination estimated at 7% (close enough to the ash content of orchard pruning residues). Therefore, the cost of orchard termination and disposal is reduced, and an additional fuel stream can be captured and directed towards the expanding bioenergy sector. Combined shredding and screening represents a further example of integration and is essential to the efficient upgrading of complete tree material into a viable fuel.

Electrolysis Assisted Biomass Gasification for Liquid Fuels Production

Gasification is a promising pathway for converting biomass residues into renewable transportation fuels and chemicals needed to comply with the ambitious Swedish environmental targets. The paper investigates the integration of a molten carbonate electrolysis cell (MCEC) in biofuel production pathway from sawmill byproducts, to improve the performance of gas cleaning and conditioning steps prior to the final conversion of syngas into liquid biofuels. The energy, material, and economic performance of process configurations with different gasification technologies are simulated and compared. The results provide relevant information to develop the engineering of gas-to-liquid transportation fuels utilizing renewable electricity. The MCEC replaces the water-gas shift step of a conventional syngas conditioning process and enables increased product throughput by as much as 15%–31%. Depending on the process configuration and steam-methane reforming technology, biofuels can be produced to the cost range 140–155 €/MWh in the short-term.

A high-throughput magnetic-based pipette tip microextraction as an alternative to conventional pipette tip strategies: Determination of testosterone in human saliva as a proof-of-concept

In this work, a lab-made and affordable high-throughput pipette tip microextraction strategy is presented. In this approach, a magnetic sorbent is quickly dispersed in the sample by means of a disperser solvent and the resulting dispersion is immediately aspirated into a pipette tip containing a small neodymium magnet inside, which entraps the magnetic sorbent containing the analytes. The sample is then discarded, and the subsequent cleaning and desorption steps are conducted by aspirating/dispensing the suitable solvents. This methodology provides satisfactory results when compared with previous pipette tip extraction strategies (i.e., pipette-tip solid-phase extraction and dispersive pipette extraction). Furthermore, it requires a minimum number of aspirating/dispensing cycles, thus benefiting the ergonomics for the operator, and it is not commercially dependent. This new approach has been tested by measuring testosterone levels in saliva of volunteers as a proof-of-concept. In this regard, a magnetic composite made of CoFe2O4 magnetic nanoparticles embedded in octadecyl bonded silica microparticles was employed as sorbent material. Testosterone was quantified by liquid chromatography coupled to tandem mass spectrometry. Under the optimized conditions, low limits of detection and quantification (7.5 ng L−1 and 24.8 ng L−1, respectively), good repeatability (RSD <9%) and relative recoveries between 82 and 106% were obtained with just one adsorption and two desorption cycles, which requires few seconds per sample. In order to increase even more the sample throughput, a multichannel pipette was also evaluated.

Microbial Culture and Scanning Electron Microscopic Evaluation of Endodontic Hand Files: An In Vitro Study.

BackgroundEndodontic hand files are used during root canal treatment in the cleaning and shaping step of the procedure. Whether endodontic instruments should be single-use or reusable is a topic of debate. This in vitro study aimed to analyze the bioburden on used and new sterilized endodontic hand files.MethodologyA total of 30 K-files (15 used, 15 new) and 30 H-files (15 used, 15 new) were studied. After clinical use, the used and new files were subjected to phloxine B staining, scanning electron microscope (SEM) analysis, and microbial culture. We used a Fisher’s exact test to investigate the significant difference in contamination and bioburden between new and used endodontic files.ResultsThe chi-square test showed no statistically significant difference between new and used groups in staining. In the used group, 20% of the H-files and 6.7% of the K-files were positive for bioburden (p > 0.05). The SEM analysis showed that all used files (100%) were contaminated with biological debris. All new files and most of the used files (86.7%) were negative for bacterial culture.ConclusionsUsed K-files and H-files (sizes 25 and below) had greater contamination and bioburden than new files. Our results highlight the inadequacy of cleaning methods (mechanical/ultrasonication pre-cleaning and heat sterilization) employed between re-usage of files in this study. Appropriate decision-making on either adapting an evidence-based and effective reprocessing strategy or single-use files can be considered by dentists.