Cleaning Step Research Articles

An improved lesion detection approach based on similarity measurement between fuzzy intensity segmentation and spatial probability maps

The application of automatic segmentation methods in lesion detection is desirable. However, such methods are restricted by intensity similarities between lesioned and healthy brain tissue. Using multi-spectral magnetic resonance imaging (MRI) modalities may overcome this problem but it is not always practicable. In this article, a lesion detection approach requiring a single MRI modality is presented, which is an improved method based on a recent publication. This new method assumes that a low similarity should be found in the regions of lesions when the likeness between an intensity based fuzzy segmentation and a location based tissue probabilities is measured. The usage of a normalized similarity measurement enables the current method to fine-tune the threshold for lesion detection, thus maximizing the possibility of reaching high detection accuracy. Importantly, an extra cleaning step is included in the current approach which removes enlarged ventricles from detected lesions. The performance investigation using simulated lesions demonstrated that not only the majority of lesions were well detected but also normal tissues were identified effectively. Tests on images acquired in stroke patients further confirmed the strength of the method in lesion detection. When compared with the previous version, the current approach showed a higher sensitivity in detecting small lesions and had less false positives around the ventricle and the edge of the brain.

A simple and sensitive method for determination of melatonin in plasma, bile and intestinal tissues by high performance liquid chromatography with fluorescence detection

This paper describes the development of a simple and sensitive method for routine quantification of melatonin in low sample amounts by using standard equipment of HPLC with fluorescence detection. A double chloroform extraction with an intermediate cleaning step with 0.1N NaOH allowed to concentrate melatonin and to avoid interferences in extracts of the different tissues assayed. The analytical procedure was found to be precise and linear for a wide range of melatonin concentrations. The retention time of melatonin was about 9min and the recoveries were in the range of 89–94%. The lower limit of quantification estimated on extracted samples was 8pg/ml. This method was validated in daytime and nighttime samples of plasma, bile and intestinal tissues of trout.

Analysis of waxes on historical samples by thin-layer chromatography

Analysis of the composition of binders applied to different historical objects is an important analytical task. On the basis of the results from this investigation, different cleaning, conservation, and restoration steps may be applied without a danger of damaging the treated materials. Very often the binders are mixtures of natural materials such as waxes, resins, proteins, and sugars. In this work thin-layer chromatography on silica gel 60 F 254 plates with petroleum ether-diethyl ether-acetic acid 90:10:1 ( ν/ν ) as mobile phase was used to identify the unknown waxes in binding media on several different historical samples. Visualization was performed under UV light at 254 nm. The waxes identified were carnauba, candelilla, and lanolin.

Novel sulfur and selenium containing bis-α-amino acids from 4-hydroxyproline

The synthesis of new substituted prolines carrying at C-4 a second alpha-amino acid residue is reported. The amino acid, L-cysteine or L-selenocysteine, is linked to the proline ring through the sulfur or the selenium atom, respectively. The products were prepared with different stereochemistry at C-4, in few and clean high-yielding steps, with suitable protections for solid phase applications. The introduction of both sulfur and selenium atoms at C-4 of the proline ring seems to enhance significantly the cis geometry at the prolyl amide bond.

Photovoltaic substrates and hafnium based gate dielectrics characterized with total reflection X-ray fluorescence

In this study, the capabilities of total reflection X-ray fluorescence spectroscopy characterization for both the photovoltaic industry and advanced semiconductor processing were investigated. Analysis of single crystal silicon coupon samples from various cleans during photovoltaic processing showed that certain clean steps were more effective in removing trace metal contamination. The multicrystalline photovoltaic silicon sample also had detected, but difficult to quantify, metallic contamination. Changes in the silicon dioxide content of hafnium silicate films used in semiconductor processing were also characterized by total reflection X-ray fluorescence spectroscopy analysis.

Mg/Ca in the benthic foraminifera Cibicidoides wuellerstorfi and Cibicidoides mundulus: Temperature versus carbonate ion saturation

Magnesium/calcium (Mg/Ca) ratios in two widely used benthic foraminiferal species, Cibicidoides wuellerstorfi and Cibicidoides mundulus ( Cibicidoides kullenbergi), picked from global ocean core-tops and from six cores in the North Atlantic Ocean have been measured to investigate Mg/Ca variability, cleaning effect, and influences from bottom water temperature (BWT) and deep water carbonate ion saturation (Δ[CO 3 2−]). Replicate measurements of the two species reveal Mg/Ca variability of 0.07 ± 0.07 mmol/mol. Compared with Mg/Ca in samples cleaned by oxidative cleaning, Mg/Ca ratios are significantly lowered, by 0.10 ± 0.09 mmol/mol, in samples cleaned by reductive cleaning, likely due to preferential leaching during the reductive cleaning step. The cleaning influence is large relative to glacial–interglacial Mg/Ca changes (0.05–0.31 mmol/mol by this study). Regression of core-top data from a wide range of locations show that C. wuellerstorfi Mg/Ca is strongly affected by deep water Δ[CO 3 2−] with a sensitivity of ~ 0.009 mmol/mol per µmol/kg. When BWT is included in regressions, the correlation is slightly more significant with a weak BWT sensitivity on Mg/Ca of between 0.03 ± 0.01 and 0.07 ± 0.02 mmol/mol per °C. Because Δ[CO 3 2−] and BWT co-vary for most core-top samples, an alternate method of separating the two effects was made by comparing glacial to interglacial changes in Mg/Ca from a depth transect of North Atlantic cores where the BWT and carbonate ion histories since the last glacial period have been well constrained. Results from this transect suggest that the BWT effect is < 0.03 mmol/mol per °C, weaker than inferred from the core-top study. Therefore, core-top and down core data suggest that C. wuellerstorfi Mg/Ca is insensitive to BWT changes. The weak BWT effect, when compared with natural variability, complicates the use of Mg/Ca in this species to reconstruct past BWT. Taking all measured samples from various environments into account, C. mundulus Mg/Ca ratios show no correlation with BWT or deep water Δ[CO 3 2−].

A new method for the evaluation of the reversible and irreversible fouling propensity of MBR mixed liquor

In this paper, a new fouling measurement method is presented as a pragmatic approach to determine a mixed liquor's fouling propensity. The MBR-VFM (VITO Fouling Measurement) uses a specific measurement protocol consisting of alternating filtration and physical cleaning steps, which enables the calculation of both the reversible and the irreversible fouling resistances. The MBR-VFM principle, set-up and measurement protocol are described as well as the evaluation of the fouling measurement method. Finally, the MBR-VFM was validated by comparing the fouling propensity measured on-line by the MBR-VFM in a lab-scale MBR with the fouling of the MBR membranes themselves. Our experiments indicated that the MBR-VFM can accurately measure fouling and that it can even be detected earlier than can be seen from the on-line filtration data of the lab-scale system itself. Furthermore, the differences measured in reversible and irreversible fouling seemed to be related to the observed impact of physical and chemical cleaning respectively. Therefore, the application of the MBR-VFM as an on-line sensor in an advanced control system, enabling the deployment of the measured fouling data for the control of membrane cleaning, seems feasible and will be tested in the near future.

Microwave-assisted multi-step synthesis of novel pyrrolo-[3,2- c]quinoline derivatives

A new approach for the synthesis of original substituted pyrrolo-[3,2- c]quinoline derivatives using microwave-assisted chemistry is described. The use of microwave activation in this synthesis resulted in high yielding and clean steps. The key step for introducing diversity is the amination or the Pd-catalyzed cross-coupling of an imidoyl chloride derivative, obtained in a straightforward manner and in good yield.

Novel Extended-Pi Shaped Silicon–Germanium Source/Drain Stressors for Strain and Performance Enhancement in p-Channel Tri-Gate Fin-Type Field-Effect Transistor

Strained p-channel tri-gate fin-type field-effect transistor (FinFET) with extended-Pi (eΠ) shaped SiGe source/drain (S/D) is demonstrated with enhanced drive current performance of 33% at a fixed drain induced barrier lowering (DIBL) over FinFET with Π-SiGe S/D. The eΠ S/D stressor structure can be easily formed by simply using a longer HF cleaning time prior to the growth of SiGe in the S/D regions. The longer HF cleaning step created a recess into the buried oxide which allows SiGe to be grown below the base of the Si fin at the S/D regions, providing additional strain to the channel. Enhancement of device performance was also found to increase with the decrease of fin width and this benefit aggressively scaled tri-gate FinFET for advance technology node.

Regio- and Stereoselective Synthesis of Thiazole-Substituted Histamine and Adenine Derivatives by Nucleophilic Attack at Allenyl Isothiocyanate

The ambident oligonucleophiles histamine and adenine were reacted with allenyl isothiocyanate to yield N-(5-methylthiazol-2-yl) substituted derivatives of the natural products. Whereas histamine led selectively in three clean steps or alternatively in a one-pot procedure to a final product bearing three thiazole units, adenine gave exclusively the mono derivative with a thiazolyl group at N-7. The regio- and stereochemistry of these transformations were proved by single-crystal X-ray analyses of the title compounds.

Bench-Scale Production of Hydrocarbon Liquid Fuel from Woody Biomass via Gasification

The bench-scale production of hydrocarbon liquid fuel was successful from woody biomass via gasification. The production capacity of the biomass-to-liquid (BTL) plant used in this study was 1.9 L of hydrocarbon liquid from 13 kg of woody biomass per day. The BTL process involved the following steps: gasification of the woody biomass, wet and dry gas cleaning, gas compression, the removal of carbon dioxide, and the Fischer-Tropsch (FT) synthesis reaction. In the gasification step, oxygen-enriched air gasification was carried out using a downdraft fixed-bed gasifier. By increasing the oxygen content, which acts as a gasifying agent, from 21.0 to 31.5 vol%, the conversion to gas on a carbon basis increased from 91.9 to 96.3 C-mol%, while the concentrations of CO and H2 increased from 22.8 to 30.1 vol% and from 16.8 to 23.7 vol%, respectively. The product gas obtained with an oxygen content of 27.6 vol% was subsequently converted to a liquid fuel through the gas cleaning and FT synthesis reaction steps. The concentrations of H2S and COS produced in the gasification step decreased to less than 5 ppb through the scrubber and desulfurization tower for the wet and dry gas cleaning, respectively. The concentration of the syngas (CO + H2) increased from 48.1 to 56.0 vol%, while that of CO2 decreased from 12.1 to 0.6 vol% after the cleaned gas was passed through a carbon dioxide removal tower. Subsequently, the cleaned gas was compressed up to 12.6 MPa using compressors to obtain a feed gas for the FT synthesis reaction, and its composition was as follows: 30.8 vol% of CO, 25.2 vol% of H2, 0.9 vol% of CO2, 2.5 vol% of CH4, 40.6 vol% of N2, <5 ppb of H2S, and <5 ppb of COS. In the FT synthesis step, the hydrocarbon fuel was synthesized in a slurry bed reactor using hexadecane as the solvent and Co/SiO2 catalyst. The selectivity to hydrocarbon with a carbon chain length of more than 5 carbon atoms as a liquid fuel, i.e., a C5+ selectivity of 73.0% was obtained along with a chain growth probability of 0.85 under the following conditions: 3 MPa, 280 to 310°C, and when the ratio of catalyst weight to feed gas rate (W/F) was 86.9 g h/mol.

Determination of Mercury by Anodic Stripping Voltammetry with a Gold Nanoparticle‐Modified Glassy Carbon Electrode

AbstractThe aim of this work is the development of a procedure for the determination of aqueous Hg(II) by anodic stripping voltammetry at a gold nanoparticle‐modified glassy carbon electrode (AuNPs‐GCE). The signal of aqueous Hg(II) was measured in the square wave mode; the effect of potential scan parameters, deposition potential and deposition time on the analytical signal was examined. The supporting electrolyte was 0.06 M HCl. The repeatability, the linearity, the accuracy, the detection limit of the procedure and the interferences of other cations and of anions were evaluated. The performance of the AuNPs‐GCE was compared with those of a solid (SGE) and a film (FGE) gold electrode: the AuNPs‐GCE showed to provide lower detection limits and higher repeatability. The renewable surface permits to eliminate memory effects, to maintain a stable baseline and response, and to avoid frequent mechanical cleaning steps. The applicability of the AuNPs‐GCE for Hg(II) determination in drinking waters, sediments and pharmaceuticals was demonstrated.

Novel Bitumen Froth Cleaning Device and Rag Layer Characterization

A primary bitumen froth product, from a bitumen extraction process, contains approximately 30% water, 10% solids, and 60% bitumen. In bitumen froth treatment vessels, “rag layer” between the top organic phase and the bottom aqueous phase builds up from time to time. The presence of a thick layer of rag renders a two-phase separation into a three-phase separation, causing a significant reduction in oil/water/solids separation efficiency. A novel setup was built in our laboratory, which allows for a two-step water washing of naphtha-diluted bitumen froth (NDBF) and buildup of rag layer to be collected efficiently for further investigation of rag formation mechanisms. In the first step of bitumen froth cleaning, 1–5 mm diameter NDBF drops were introduced into an aqueous phase to allow the NDBF drops to rise to the top as the organic phase. In the second step, the top organic phase was then washed using the bottom aqueous phase by circulating the top organic phase back to the aqueous phase. The bitumen froth ...

Energy recovery from sewage sludge by means of fluidised bed gasification

Because of its potential harmful impact on the environment, disposal of sewage sludge is becoming a major problem all over the world. Today the available disposal measures are at the crossroads. One alternative would be to continue its usage as fertiliser or to abandon it. Due to the discussions about soil contamination caused by sewage sludge, some countries have already prohibited its application in agriculture. In these countries, thermal treatment is now presenting the most common alternative. This report describes two suitable methods to directly convert sewage sludge into useful energy on-site at the wastewater treatment plant. Both processes consist mainly of four devices: dewatering and drying of the sewage sludge, gasification by means of fluidised bed technology (followed by a gas cleaning step) and production of useful energy via CHP units as the final step. The process described first (ETVS-Process) is using a high pressure technique for the initial dewatering and a fluidised bed technology utilising waste heat from the overall process for drying. In the second process (NTVS-Process) in addition to the waste heat, solar radiation is utilised. The subsequent measures--gasification, gas cleaning and electric and thermal power generation--are identical in both processes. The ETVS-Process and the NTVS-Process are self-sustaining in terms of energy use; actually a surplus of heat and electricity is generated in both processes.

Using Megasonics to Extend Chemical Cleans for 45nm Technology

Aqueous and solvent chemicals are widely used in the semiconductor industry and as the technology nodes shrink device makers are working to extend these cleaning fluids to the next technology node. Internal data shows megasonic agitation can enhance polymer removal without complete dissolution for both aqueous and solvent chemicals. However, today, front end of line post reactive ion etch polymer removal clean steps are preformed with cheap aqueous commodity chemicals. So, this paper will look into the possibility of extending aqueous cleans to the next technology node using megasonic agitation.

Evaluation of top, angle, and side cleaned FIB samples for TEM analysis

TEM specimens of a LaAlO(3)/SrTiO(3) multilayer are prepared by FIB with internal lift out. Using a Ga(+1) beam of 5 kV, a final cleaning step yielding top, top-angle, side, and bottom-angle cleaning is performed. Different cleaning procedures, which can be easily implemented in a dual beam FIB system, are described and compared; all cleaning types produce thin lamellae, useful for HRTEM and HAADF-STEM work up to atomic resolution. However, the top cleaned lamellae are strongly affected by the curtain effect. Top-angle cleaned specimens show an amorphous layer of around 5 nm at the specimen surfaces, due to damage and redeposition. Furthermore, it is observed that the LaAlO(3) layers are preferentially destroyed and transformed into amorphous material, during the thinning process.

Synthesis and characterization of sulphonated core-shell latices in the size range between 30 and 80 nm

The objective of the current work was the synthesis of sulphonated core-shell nanolatices and to investigate to which extend it is possible to control the final surface charge of such latices. For this purpose differently sized polystyrene seed latices with average diameters in the size range between 30 and 80 nm were synthesized by emulsion polymerization. To obtain the final latices, a sulphonated comonomer was incorporated in the outer surface shell of the particles by further reaction of the seed latices with styrene and sodium styrene sulphonate (NaSS). In a first test series the seed latex surface was modified with four different amounts of NaSS. In a second test series four different seed latices were reacted with the same amount of NaSS. In the last set of reactions the seed latices were reacted with different amounts of NaSS and in these reactions the ratio of added NaSS to the specific surface area of the seed latex was kept constant to obtain differently sized latices of the same surface charge density. The yield of sulphonic acid groups in the particle shell was found between 57 and 74% after an intensive cleaning step by ion exchange. The results show possibilities for a reproducible synthesis of small sulphonated latex particles with a desired surface charge density.

Production of recombinant adeno-associated vectors using two bioreactor configurations at different scales

The conventional methods for producing recombinant adeno-associated virus (rAAV) rely on transient transfection of adherent mammalian cells. To gain acceptance and achieve current good manufacturing process (cGMP) compliance, clinical grade rAAV production process should have the following qualities: simplicity, consistency, cost effectiveness, and scalability. Currently, the only viable method for producing rAAV in large-scale, e.g. ≥10 16 particles per production run, utilizes baculovirus expression vectors (BEVs) and insect cells suspension cultures. The previously described rAAV production in 40 L culture using a stirred tank bioreactor requires special conditions for implementation and operation not available in all laboratories. Alternatives to producing rAAV in stirred tank bioreactors are single-use, disposable bioreactors, e.g. Wave™. The disposable bags are purchased pre-sterilized thereby eliminating the need for end-user sterilization and also avoiding cleaning steps between production runs thus facilitating the production process. In this study, rAAV production in stirred tank and Wave™ bioreactors was compared. The working volumes were 10 L and 40 L for the stirred tank bioreactors and 5 L and 20 L for the Wave™ bioreactors. Comparable yields of rAAV, ∼2E+13 particles per liter of cell culture were obtained in all volumes and configurations. These results demonstrate that producing rAAV in large scale using BEVs is reproducible, scalable, and independent of the bioreactor configuration.

THEORETICAL STUDIES ABOUT ADSORPTION ON SILICON SURFACE

In this review paper, we address the important research topic of adsorption on the silicon surface. The deposition of single Si ad-species (adatom and ad-dimer) on the p(2×2) reconstructed Si (100) surface has been simulated by the empirical tight-binding method. Using the clean and defective Si surfaces as the deposition substrates, the deposition energies are mapped out around the clean surface, dimer vacancies, steps and kink structures. The binding sites, saddle points and several possible diffusion paths are obtained from the calculated energy. With further analysis of the deposition and diffusion behaviors, the influences of the surface defects can be found. Then, by adopting the first-principle calculations, the adsorptions of the II-VI group elements on the clean and As-passivated Si (211) substrates have been calculated as the example of adsorption on the high-miller-index Si surface.

Preferential dissolution of benthic foraminiferal calcite during laboratory reductive cleaning

We have investigated the effect of cleaning procedures on eight element/Ca ratios in three widely used benthic foraminifera species from core top and down core sediments. Two cleaning techniques were employed: (1) comparison between “Mg‐cleaning” and “Cd‐cleaning” methods and (2) comparison between the various constituent reagents. Li/Ca, B/Ca, and Sr/Ca ratios remained unchanged for samples subjected to different treatments, but Mg/Ca, Mn/Ca, Zn/Ca, Cd/Ca, and U/Ca were substantially decreased when foraminifera shells were cleaned with reagents containing citrate. In contrast, no significant decreases in element/Ca ratios were observed for samples cleaned in N2H4 without citrate, indicating that the role of N2H4 was insignificant during reductive cleaning and that citrate is responsible for decreases of Mg/Ca, Mn/Ca, Zn/Ca, Cd/Ca, and U/Ca. Decreases in these ratios are most likely due to (1) removal of contaminant particles enriched in Mg, Mn, Zn, Cd and U and/or (2) preferential leaching of CaCO3 by the formation of stable metal complexes through chelation between citrate and metals heterogeneously distributed in foraminiferal shells. Due to the negligible effect of N2H4 and preferential dissolution of CaCO3 during reductive cleaning, it is suggested that the reductive cleaning step should be omitted and the “Mg‐cleaning” method [Barker et al., 2003] could be employed to clean foraminiferal shells for trace element measurements.