Addition Of Buffer Research Articles

Clinical performance and sample freeze-thaw stability of the cobas®6800 SARS-CoV-2 assay for the detection of SARS-CoV-2 in oro-/nasopharyngeal swabs and lower respiratory specimens.

Studies describing the performance characteristics of the cobas®6800 system for SARS-CoV-2 detection in deep respiratory specimens and freeze-thaw stability are limited. The current study compares the clinical performance of the automated SARS-CoV-2 assay on the cobas®6800 system to a lab-developed assay (LDA) and the cobas impact of freeze-thawing combined with lysis buffer. Both retrospective and prospectively selected deep respiratory samples and oro- and nasopharyngeal samples in either E-swab® or GLY- were tested using the SARS-CoV-2 assay on the cobas®6800 System and compared to a lab developed assay. Additonally, SARS-CoV-2 RNA stability was assessed after one freeze-thaw cycle with or without lysis buffer. In total, 221 (58.3 %) oro- and nasopharyngeal swabs, 131 (34.6 %) deep respiratory specimens, and n = 25 (6.6 %) swabs of unknown origin were included to study clinical performance. Only 4 samples gave discrepant results, all being positive in the LDA and not the cobas®6800 system. For stability testing, 66 samples without and 110 with lysis buffer were included. No clinically significant difference was found in test results after one freeze-thaw cycle and addition of lysis buffer. Based on our findings, the cobas®6800 SARS-CoV-2 RNA assay yielded similar results as the LDA in oro-/nasopharyngeal swabs and deep respiratory specimens. Moreover, the cobas®6800 SARS-CoV-2 RNA assay yielded similar results before and after a freeze-thaw cycle, with better preservation of low viral loads in lysis buffer.

The Large Communal Nests of Sociable Weavers Provide Year-Round Insulated Refuge for Weavers and Pygmy Falcons

The primary role of nests as structural support for eggs, nestlings, and incubating parents is well established, but our understanding of their secondary roles and their adaptive features is still limited. Nests can serve a particularly important role in protecting or buffering birds from weather. In hot, arid environments, maximum daily temperatures can exceed a species’ upper critical temperature threshold and during the non-breeding season temperatures may also drop below freezing. Nest structures that help buffer against extreme temperatures may play a crucial role in managing the costs of thermoregulation, especially those nests that are used and maintained year-round. We use extensive year-round data to investigate the thermal benefits of massive colonial structures built by sociable weavers in the arid savannahs of the Kalahari, South Africa. These colonies consist of multiple nesting chambers and are used as roosts when birds are not breeding. We explored whether these structures provide thermal buffering throughout the year and how individual chamber placement within the colony and features of the chambers influenced their thermal buffering capacity. We also investigated whether nest chambers occupied and modified by an obligate nest parasite, the African pygmy falcon provided additional thermal buffering. Our results show that sociable weaver colonies provide thermal benefits throughout the year, buffering both hot and cold ambient extremes.. Chambers with longer entrance tunnels provided better insulation than chambers with shorter entrance tunnels, and chambers located towards the centre of a colony provided greater insulation than chambers at the edge. Chambers occupied by falcons did not display additional thermal benefits, which may be due to falcons choosing chambers with shorter entrance tunnels. Because falcons are larger than weavers, they may find it harder to enter chambers with longer entrance tunnels, and/or because weavers cease maintenance of those chambers. In conclusion, the communal nests of sociable weaver provide thermal benefits to weavers and heterospecifics alike, creating a more optimal environment for breeding, roosting and reducing thermal stress. In a landscape that is becoming increasingly harsh under climate change, the importance of these structures to the local animal communities may also increase.

Evaluation of chromatographic parameters in supercritical fluid chromatography of amino acids as model polar analytes and extended to polypeptide separations

Chromatographic parameters have been evaluated regarding the supercritical fluid chromatography of amino acids as model compounds for polar and chargeable substances of biochemical and biopharmaceutical interest. Their inherent hydrophilicity requires suitable chromatographic conditions regarding stationary and mobile phase to obtain suitable solubility and peak performance. Ten stationary phases differing in polarity and type of ligands including neutral and charged ones were investigated regarding selectivity, peak performance and complementarity/orthogonality. The mobile phase composition regarding solvent and type of buffer additives by varying the degree of hydrophobicity of the acids and bases and degree of substitution in case of the basic amines. Addition of water to the methanol solvent was furthermore found crucial for obtaining a high peak performance. Some complementary selectivity could be obtained depending on a choice of column. Temperature and pressure variations basically only influenced retention with no selectivity changes. Suitable conditions obtained for the amino acids were then successfully applied to oligo- and polypeptides enabling a separation of 4 polypeptides and differing in only one of the 39 amino acids, thereby mimicking analysis of biotransformation reaction products. The utilization of water as mobile phase additive and sulfonic acids as buffer agents could serve as a generic methodology for polar and charged compounds such as amino containing biomolecules.

A Wideband CMOS Frequency Quadrupler With Transformer-Based Tail Feedback Loop

In this brief, a millimeter-wave (mm-Wave) wideband frequency quadrupler is demonstrated in a 55-nm CMOS technology. It cascades two injection-locked frequency doublers (ILFD). Each of them consists of an oscillator gain stage realized by an injection-locked oscillator (ILO) and a frequency doubler implemented by a push-push pair. A tail feedback loop is proposed and applied in the second ILFD. It effectively boosts the injection current for the second ILFD. Therefore, both the operating bandwidth and output power (Pout) of the circuit are prominently improved. In addition, transformer-based high-order resonators are used to reduce the phase variation of their impedance around 0° and hence extend the locking range of ILOs. According to the measurement results, a frequency range of 30.8 ~40 GHz is achieved. The maximum Pout is up to -7.1 dBm without additional buffers. The circuit also attains a wide 3-dB frequency bandwidth of Pout, which is from 32 to 38.4 GHz. The harmonic rejection ratios of the frequency quadrupler are 16.5 ~25.9 dBc at the second-order harmonic and 31 ~45 dBc at the fundamental and third-order harmonics over the entire operating bandwidth. The core area occupies only 0.24 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .

Fast Buffer Count Estimation in 3D IC Floorplanning

A methodology for fast and accurate estimation of the number and positions of buffers during 3D IC floorplanning is developed. Our algorithm computes candidate buffer positions simultaneously with assignment of 3D nets to TSVs. Through accurate delay characterization of buffered 3D nets, the minimum distance between consecutive buffers is estimated. Additionally, an analytical approach is used to find the optimal position of buffers in front of TSVs. This prevents additional buffers' insertion around TSVs, incurring lesser delay and power in 3D nets. Experimental results with expanded GSRC benchmarks show 5.6% more reduction in number of buffers, 5.7% reduction in interconnect delay and 4% reduction in dynamic power, compared to a previous published work. The potential impact of nanoscale TSVs on buffer estimation at sub-45 nm technologies is analyzed.

Enhanced hydrogen production in microbial electrolysis through strategies of carbon recovery from alkaline/thermal treated sludge

The aim of this study was to investigate the biohydrogen production from thermal (T), alkaline (A) or thermal-alkaline (TA) pretreated sludge fermentation liquid (SFL) in a microbial electrolysis cells (MECs) without buffer addition. Highest hydrogen yield of 36.87±4.36 mgH2/gVSS (0.026 m3/kg COD) was achieved in TA pretreated SFL separated by centrifugation, which was 5.12, 2.35 and 43.25 times higher than that of individual alkaline, thermal pretreatment and raw sludge, respectively. Separating SFL from sludge by centrifugation eliminated the negative effects of particulate matters, was more conducive for hydrogen production than filtration. The accumulated short chain fatty acid (SCFAs) after pretreatments were the main substrates for MEC hydrogen production. The maximum utilization ratio of acetic acid, propionic acid and n-butyric acid was 93.69%, 90.72% and 91.85%, respectively. These results revealed that pretreated WAS was highly efficient to stimulate the accumulation of SCFAs. And the characteristics and cascade bioconversion of complex substrates were the main factor that determined the energy efficiency and hydrogen conversion rate of MECs.

Promising Cd-free double buffer layer in CZTSSe thin film solar cells

Zn(O,S) film is widely used as a Cd-free buffer layer for kesterite thin film solar cells due to its low-cost and eco-friendly characteristics. However, the low carrier concentration and conductivity of Zn(O,S) will deteriorate the device performance. In this work, an additional buffer layer of In2S3 is introduced to modify the properties of the Zn(O,S) layer as well as the CZTSSe layer via a post-annealing treatment. The carrier concentrations of both the Zn(O,S) and CZTSSe layers are increased, which facilitates the carrier separation and increases the open circuit voltage (VOC). It is also found that ammonia etching treatment can remove the contamination and reduce the interface defects, and there is an increase of the surface roughness of the In2S3 layer, which works as an antireflection layer. Consequently, the efficiency of the CZTSSe solar cells is improved by 24% after the annealing and etching treatments. Simulation and experimental results show that a large band offset of the In2S3 layer and defect energy levels in the Zn(O,S) layer are the main properties limiting the fill factor and efficiency of these CZTSSe devices. This study affords a new perspective for the carrier concentration enhancement of the absorber and buffer layers by In-doping, and it also indicates that In2S3/Zn(O,S) is a promising Cd-free hybrid buffer layer for high-efficiency kesterite solar cells.

Monolithic Integrated High Frequency GaN DC-DC Buck Converters with High Power Density Controlled by Current Mode Logic Level Signal

Integration is a key way to improve the switching frequency and power density for a DC-DC converter. A monolithic integrated GaN based DC-DC buck converter is realized by using a gate driver and a half-bridge power stage. The gate driver is composed of three stages (amplitude amplifier stage, level shifting stage and resistive-load amplifier stage) to amplify and modulate the driver control signal, i.e., CML (current mode logic) level of which the swing is from 1.1 to 1.8 V meaning that there is no need for an additional buffer or preamplifier for the control signal. The gate driver can provide sufficient driving capability for the power stage and improve the power density efficiently. The proposed GaN based DC-DC buck converter is implemented in the 0.25 μm depletion mode GaN-on-SiC process with a chip area of 1.7 mm × 1.3 mm, which is capable of operating at high switching frequency up to 200 MHz and possesses high power density up to 1 W/mm2 at 15 V output voltage. To the authors’ knowledge, this is the highest power density for GaN based DC-DC converter at the hundreds of megahertz range.

Optimal CdS Buffer Thickness to Form High-Quality CdS/Cu(In,Ga)Se2 Junctions in Solar Cells without Plasma Damage and Shunt Paths.

CdS has been known to be one of the best junction partners for Cu(In,Ga)Se2 (CIGS) in CIGS solar cells. However, the use of thick CdS buffer decreases the short-circuit current density of CIGS solar cells. There are two obstacles that limit the use of ultrathin CdS. The first is plasma damage to CIGS during the preparation of transparent conducting windows and the second is a low shunt resistance due to the direct contact between the window and CIGS via pinholes in the thin CdS buffer. In other words, to avoid plasma damage and shunt paths, we may have to use a CdS buffer that is thicker than necessary to form a high-quality CdS/CIGS junction. This work aims to determine how thin the CdS buffer can be employed without sacrificing device performance while also eliminating the above two obstacles. We investigate the effect of CdS thickness on the performance of CIGS solar cells with silver nanowire-based window layers, which can eliminate both obstacles. An approximately 13 nm thick CdS buffer allows us to achieve high short-circuit current density and fill factor values. To attain an even high open-circuit voltage, an additional CdS buffer with a thickness of 13 nm is needed. The data from this study imply that an approximately 26 nm thick CdS buffer is sufficient to form a high-quality CdS/CIGS junction.

DAMPAK IMPLEMENTASI BASEL III TERHADAP PERMODALAN PADA BANK DI INDONESIA (STUDI KASUS PADA PT BANK NEGARA INDONESIA (PERSERO) TBK)

The purpose of this study is to measure Bank's ability to implement the Basel III and what strategies should be undertaken by Bank to meet the regulations and support business growth in terms of capital. This study uses secondary data by using the implications of the basel III on Bank capital and capital adequacy rate with the object of PT. Bank Negara Indonesia (Persero) Tbk. Results There are significant changes of BNI KPMM prior to using basel II and after using Basel III ie changes in presentation templates, post changes and movements, changes in total capital and CAR, and additional buffers. However, it is able to contribute greatly to its business, among others, BNI is still able to cover the massive withdrawal from DPK due to capital and loan growth provide large space for credit expansion through good LLL, as well as capital ability to support profit growth supported from percentage of capital. But with so many risks that accompany it and the turbulent business climate and additional buffers, BNI still have to increase its capital again to be able to support the aggressive BNI business.

Development of a simple multiresidue extraction method for the quantification of a wide polarity range list of pesticides and transformation products in eggs by liquid chromatography and tandem mass spectrometry.

Waterfowl populations have been decreasing in Europe for the last years and pollution appears to be one of the main factors. This study was conducted to develop a single sensitive and robust analytical method for the monitoring of 2 fungicides, 15 herbicides, 3 insecticides and 24 transformation products in wild bird eggs. One of the major challenges addressed was the characterization of chemicals with large logP range (from -1.9 to 4.8). A total of 11 different extraction parameters were tested in triplicate to optimize the extraction protocol, on generic parameters, buffer addition and use of clean-up steps. Quantification was based on matrix-match approach with hen eggs as reference matrix (34 analytes with r²>0.99). Particular attention was payed to matrix effects (-28% on average), quantification limits (0.5 to 25ng.g-1 dry mass / 0.2 to 7.5ng.g-1 fresh mass) and extraction yields (46 to 87% with 25 analytes up to 70%) to ensure the relevance of the method and its compatibility with ultra-trace analysis. It led to a simple solid/liquid low temperature partitioning extraction method followed by LC-MS/MS. Analysis of 29 field samples from 3 waterfowl species revealed that eggs were slightly contaminated with pesticides as only one egg presented a contamination (terbutryn, herbicide, 0.7ng.g-1) and confirmed the relevance of the method.

A Wide Tunable Hysteresis CML Delay Cell for High Frequency

In this letter, a novel high-speed widely tunable voltage-controlled current mode logic (CML) delay cell is implemented in a 65-nm CMOS technology. Variation in the delay of the proposed delay cell is based on the hysteresis control of the output switching threshold by altering the tail current of the CML buffer. The simulation for a single stage cell shows a delay variation of at least 11% in the input clock period at 12.5-GHz clock frequency. While in measurement, the delay line with three stages of the proposed cells shows more than a 38-ps delay variation with an output rms jitter of 1.67 ps for the 9.82-GHz input clock frequency. At this frequency with the highest delay variation, along with additional buffers and delay controllers, the delay line consumes 7.6 mW of power with 1.2-V core supply. The delay line consumes the silicon area of 0.0285 mm2 in the 65-nm technology node.

Enhancement of piezoelectric properties of lithium niobate thin films by different annealing parameters

Piezoelectric materials with useful properties find a wide range of applications including opto- and acousto- electronics. Lithium niobate in the form of a thin film is one of those promising materials and has a potential to improve ferroelectric random access memories devices, optical waveguides or acoustic delay lines by virtue of its physical characteristics, e.g. electro-optic coefficient, acoustic velocity, refractive indices etc. The key challenge to overcome is lithium nonstoichiometry as it leads to the appearance of parasite phases and thus aggravates physical and structural properties of a film. According to literature data, in order to obtain microcrystalline piezoelectric phase in previously amorphous films a set of methods is used. In our case we tried to synthesize LN films using congruent target and non-heated silicon substrate and then attain the piezoelectric phase by different annealing parameters. Afterwards LN films were compared to the ones synthesized on the silicon substrate with an additional buffer layer of platinum. Samples were studied by scanning probe microscope. Self-polarization vectors were defined. Based on domain structure images, the histograms of distribution of piezoresponse signals were built.

Biomolecular interactions of selected buffers with hemoglobin

To elucidate the influence of commonly used biological buffers on the hemoglobin (Hb) structure, biomolecular interactions between Hb and the selected buffers, including tris (hydroxymethyl) aminomethane (TRIS), N-[tris (hydroxymethyl) methyl]-3-aminopropanesulfonic acid (TAPS) and N-[tris (hydroxymethyl) methyl]-2-aminoethane-sulfonic-acid (TES), are investigated by using various biophysical spectroscopic and other techniques. The techniques used in this study are ultraviolet–visible (UV–Vis), fluorescence, circular dichroism (CD) and Fourier transform infrared spectroscopy and dynamic light scattering. Fluorescence spectra analysis reveals that the addition of biological buffers increases the hydrophobicity around the tryptophan environment in Hb. Evidently, the alpha-helix structure of Hb was slightly destroyed at higher concentrations of the buffers detected by CD spectroscopy. However, the thermal stability of the protein transition temperature (Tm) gradually increases with an increase in the concentration of the biological buffers. The results also show that generally the biological buffers are able to enhance the stability of Hb.

Appraisal and social support as moderators between stress and physical and psychological quality of life.

One proposed mechanism of social support is the facilitation of primary and secondary reappraisal of stressful situations. The current study examined the expansion of the original stress-buffering hypothesis to include primary or secondary appraisal in an emerging adult population (N = 854) on physical and psychological health outcomes. The additional moderating effects of gender also were examined. Perceived social support (by the Multidimensional Survey of Perceived Social Support) significantly buffered the effects of stress from negative events (by the Risky Behaviour and Stressful Events Scale) on physical and psychological health (by the World Health Organizations Quality of Life Instrument) for females only. Neither primary nor secondary appraisal (by the Stress Appraisal Measure) acted as additional buffers for male or females. Social support may be a more salient buffer for females. Reappraisal mechanisms may have another role in the buffering pathways. Further implications and limitations were discussed.

Preparing Immunoprecipitations for Immunoblotting.

Immunoprecipitated proteins can be readily analyzed by immunoblotting. Proteins can be efficiently eluted from the Protein A or similar beads by addition of the SDS-PAGE sample loading buffer and heating at 95°C. This elution procedure will also remove the capturing antibody from the beads unless the antibody was cross-linked to the beads. Alternatively, the immunoprecipitated proteins as well as non-cross-linked capture antibodies can be eluted from the beads using low (2.1-2.8) or high (10-11) pH conditions. Incubation of the immunoprecipitates with the excess of the competing peptide allows the elution of the captured proteins without contamination of the sample with the antibodies present in the immunoprecipitates. However, this option is not always available, and the cost of competing peptide can be prohibitive for the routine immunoprecipitation/immunoblotting experiments. In this protocol, elution of the immunoprecipitated proteins from the beads is performed by mixing Protein A or similar beads containing the immunoprecipitated protein antigens of interest with SDS-PAGE sample buffer and boiling to prepare samples for protein gel electrophoresis.

TEG PlateletMapping assay results may be misleading in the presence of cold stored platelets.

Viscoelastic tests (VETs) are used widely to monitor hemostasis in settings such as cardiac surgery. There has also been renewed interest in cold stored platelets (CSPs) to manage bleeding in this setting. CSPs are reported to have altered hemostatic properties compared to room temperature platelets (RTPs), including activation of GPIIb/IIIa. We investigated whether the functional differences between CSP and RTP affected the performance of the PlateletMapping VET on the TEG 5000 and 6s analyzer. Platelet concentrates were divided equally into CSP (stored at 4°C ± 2°C) and RTP (stored at 22°C ± 2°C) fractions. Whole blood was treated to induce platelet dysfunction (WBIPD) by incubating with anti-platelet drugs (1.0 μM ticagrelor and 10 μM aspirin) or by simulating cardiopulmonary bypass. WBIPD samples were then mixed with 20% by volume of CSPs or RTPs to model platelet transfusion before analysis using the PlateletMapping VET. Addition of CSPs to WBIPD increased the PlateletMapping MAFIBRIN and MAADP parameters with the TEG 5000 analyzer (both p < 0.0001 compared to addition of buffer alone). This effect was not observed with RTPs. The differential effect of CSPs on the MAFIBRIN corrected after pre-incubation with the GPIIb/IIIa antagonist tirofiban and was quantitatively less with the PlateletMapping test for the TEG 6s analyzer which contains the GPIIb/IIa antagonist abciximab. The PlateletMapping MAFIBRIN and MAADP test results may be misleadingly high with CSPs, particularly with the TEG 5000 analyzer, most likely due to constitutive activation of GPIIb/IIIa on CSPs during storage. TEG PlateletMapping results should be interpreted with caution following CSP transfusion.

A new application of acetylation for analysis of acidic heteropolysaccharides by liquid chromatography-electrospray mass spectrometry

A novel ultra-high-performance liquid chromatography-electrospray mass spectrometry (UHPLC-ESI-MS) method was proposed for simultaneous determination of neutral and acidic monosaccharaides by employing acetylation derivatization that is specialized for gas chromatography-mass spectrometry (GC-MS) analyses. The UHPLC-ESI-MS was carried out in a positive ionization mode with selective ion monitoring (SIM) of sodium adducts at m/z 385 (Ara, Xyl and Rib), 399 (Rha and Fuc), 443 (Glc, Gal and Man) and 457 (GlcA and GalA). The separation was achieved on a Cortecs C18+ (2.1 mm × 150 mm, 1.6 μm) within 8 min using acetonitrile water as the mobile phase without additional buffer salt added. Furthermore, quantitative analysis of the multi-monosaccharaides by single marker (QAMS) was developed and validated using a relative correction factor. The UHPLC-ESI-MS and QAMS were compared and successfully applied to analyze the monosaccharide contents of a purified acidic heteropolysaccharide previously isolated from Ephedra sinica. The established UHPLC-ESI-MS and QAMS approach possesses high precision, stability and repeatability, and can be widely used for high-throughput analysis of the monosaccharide compositions of plant polysaccharides.

Buffer pKa Impacts the Mechanism of Hydrogen Evolution Catalyzed by a Cobalt Porphyrin-Peptide.

The effect of buffer pKa on the mechanism of electrochemical hydrogen evolution catalyzed by a cobalt porphyrin peptide (CoMP11-Ac) at constant pH is presented. The addition of buffer to CoMP11-Ac in water and KCl leads to an enhancement of the catalytic current of up to 200-fold relative to its value in the absence of a buffer. Two distinct catalytic regimes are identified as a function of the buffer pKa. In the presence of buffers with pKa ≤ 7.4, a fast catalysis regime limited by diffusion of buffer is reached. The catalytic half-wave potential (Eh) shifts anodically (from -1.42 to -1.26 V vs Ag/AgCl/KCl(1M)) as the buffer pKa decreases from 7.4 to 5.6, proposed to result from fast Co(III)-H formation following the catalysis-initiating Co(II/I) reduction. With higher-pKa buffers (pKa > 7.7), an Eh = -1.42 V, proposed to reflect the Co(II/I) couple, is maintained independent of the buffer pKa, consistent with rate-limiting Co(III)-H formation under these conditions. We conclude that the buffer species pKa impacts catalytic current and potential and the rate-determining step of the reaction.

Sequential injection analysis Ferrozine spectrophotometry versus Luminol chemiluminescence for continuous online monitoring of the concentration and speciation of iron

We designed two sequential injection analysis systems (Luminol chemiluminescent and Ferrozine spectrophotometric) that are capable of monitoring the concentration of soluble iron(II) and reducible iron(III) in natural waters over extended periods (>120 h). The method based on Luminol chemiluminescence estimated the iron(II) concentration as the difference in signal with or without the addition of the strong iron(II) ligand, FerrozineTM (iron complexing reagent). Iron(II) in the sample without the iron complexing reagent induced a chemiluminescence signal whereas iron(II) in the presence of the iron complexing reagent did not induce a signal. The second method, based on FerrozineTM spectrophotometry, measured iron(II) and reducible iron(III) in a 100 cm path length liquid wave capillary cell. Both methods provided stability for >120 h and yielded similar analytical detection limits equal to ten standard deviations of the blank; 2.2 nM for Luminol chemiluminescence with a calibration concentration range of 0−12 nM, and 3.9 nM for FerrozineTM spectrophotometry with a calibration concentration range of 0−120 nM. The two chemical techniques do not appear to be directly comparable for practical monitoring purposes, and we suggest that Luminol-chemiluminescence is unable to measure strong ligand complexes of iron(II). Both methods used iron(II) as the analytical standard rather than a reduced iron(III) standard. The analysis based on the iron(II) standard was able to be performed without additional buffers and reducing reagents, which significantly minimized contamination.