Variety Of Different Samples Research Articles

Multilayer diffusion modeling and Coherent anti-Stokes Raman scattering microscopy for spatially resolved water diffusion measurements in human skin.

In this work using Coherent anti-Stokes Raman Scattering microscopy, it was possible to directly measure the time dependent, spatially resolved change in concentration of water (D2 O) in intact skin tissue with a spatial resolution of under 1μm, and combined with a multilayer diffusion model, diffusion coefficients at different depths in the tissue were extracted. The results show that the diffusion varies at different layers throughout the Stratum Corneum (SC), indicating that the SC is not a homogeneous barrier but a complicated heterogeneous structure. Interestingly, averaging over the diffusion at the different depths and samples gave a relatively constant value of 0.047 ± 0.01 μm2 /second. Treating the skin with acetone or tape stripping led to an increased diffusion coefficient of 0.064 ± 0.02 μm2 /second and 0.079 ± 0.03 μm2 /second, respectively. The combined method and model presented here shows potential for wide applications for measuring spatially resolved diffusion of different substances in a variety of different samples.

Nanotechnological immunoassay for rapid label-free analysis of candidate malaria vaccines.

Malaria is a life-threatening epidemic disease with half of the world's population at risk. Although its incidence rate has fallen since 2010, this ratio dramatically stalled between 2014 and 2018. New fast and optimized tools in vaccine analysis and seroconversion testing are critically needed. We developed a clinical diagnostic device based on piezo-actuated nanoresonators that perform as quantitative in situ calibrated nano-bio sensors for specific detection of multiple target molecules in serum samples. The immunoassay successfully diagnoses humoral immune responses induced by malaria vaccine candidates and reveals the timeline and stage of the infection. We applied the newly developed strategy to a variety of different samples, from pure antibody/vaccine solutions, to blood samples from clinical trials on both naïve and pre-exposed malaria volunteers from sub-Saharan countries. Our nanomechanical assay provides a direct one-step label-free quantitative immunoassay that is on par with the gold-standard, multi-step enzyme-linked immunosorbent assay (ELISA). We achieve a limit of detection of few pg ml-1, or sub-pM concentrations. The 6 μl sample volume allows more than 50 experiments from one finger prick. Furthermore, we simultaneously detected multiple analytes by differential functionalization of multiple sensors in parallel. The inherent differential read-out with in situ controls reduces false positive results. Due to the faster turnaround time, the minimal volume required and the automatized handling system, this technique has great potential for miniaturization and routine diagnostics in pandemic emergencies.

Tip Recycling for Atomic Force Microscopy-Based Tip-Enhanced Raman Spectroscopy.

Tip-enhanced Raman spectroscopy (TERS) is a powerful tool for the characterization of surfaces and two-dimensional materials, delivering both topographical and chemical information with nanometer-scale spatial resolution. Atomic force microscopy (AFM)-TERS combines AFM with a Raman spectrometer and is a very versatile technique, capable of working in vacuum, air, and liquid, and on a variety of different samples. A metalized AFM tip is necessary in order to take advantage of the plasmonic enhancement. The most commonly used metal is Ag, thanks to its high plasmonic activity in the visible range. Unfortunately, though, the tip metallization process is still challenging and not fully reliable, yielding inconsistent enhancement factors even within the same batch of tips; as a consequence, many tips are usually prepared at once (for a single experiment), to ensure that at least one of them is sufficiently active. As the lifetime of an unprotected, Ag-coated plasmonic probe is only a few hours, the procedure is inefficient and results in a substantial waste of materials and money. In this work, we establish a cleaning routine to effectively re-use Ag-coated AFM-TERS probes, drastically reducing costs without compromising the quality of the experimental results.

Improved Ray Tracing on Random Pyramid Texture via Application of Phong Scattering

This paper presents an experimental investigation into the light trapping within silicon wafers textured by upright random pyramids. In prior studies, the conventional approach to simulating random pyramids agrees poorly with experimental data at wavelengths greater than 1000 nm in which internal light trapping becomes significant. In this work, we show that expanding the optical simulation to include Phong scattering (with an exponent of 25) improved the agreement between simulation and measurement in regard to hemispherical reflectance, transmittance, and absorptance over the range of 1000–1200 nm. The best-fit Phong exponent was not significantly altered by substrate waviness, structure symmetry, or deposition of a dielectric layer. Thus, the value of the Phong exponent determined in this study is applicable to a variety of different samples textured with upright random pyramids. In addition, the simulated angular reflectance at 532 nm shows a closer agreement with the experimental results in literature when Phong scattering is included.

Modeling and Measuring Viscoelasticity with Dynamic Atomic Force Microscopy

The interaction between a rapidly oscillating atomic force microscope tip and a soft material surface is described using both elastic and viscous forces with a moving surface model. We derive the simplest form of this model, motivating it as a way to capture the impact dynamics of the tip and sample with an interaction consisting of two components: interfacial or surface force, and bulk or volumetric force. Analytic solutions to the piece-wise linear model identify characteristic time constants, providing a physical explanation of the hysteresis observed in the measured dynamic force quadrature curves. Numerical simulation is used to fit the model to experimental data and excellent agreement is found with a variety of different samples. The model parameters form a dimensionless impact-rheology factor, giving a quantitative physical number to characterize a viscoelastic surface that does not depend on the tip shape or cantilever frequency.

Sensitive, Robust, and Cost-Effective Approach for Tyrosine Phosphoproteome Analysis.

Albeit much less abundant than Ser/Thr phosphorylation (pSer/pThr), Tyr phosphorylation (pTyr) is considered as a hallmark in cellular signal transduction. However, its analysis at the proteome level remains challenging. The conventional immunopurification (IP) approach using antibodies specific to pTyr sites is known to have low sensitivity, poor reproducibility and high cost. Our recent study indicated that SH2 domain-derived pTyr-superbinder is a good replacement of pTyr antibody for the specific enrichment of pTyr peptides for phosphoproteomics analysis. In this study, we presented an efficient SH2 superbinder based workflow for the sensitive analysis of tyrosine phosphoproteome. This new method can identify 41% more pTyr peptides than the previous method. Its excellent performance was demonstrated by the analysis of a variety of different samples. For the highly tyrosine phosphorylated sample, for example, pervanadate-treated Jurkat T cells, it identified over 1800 high confident pTyr sites from only 2 mg of proteins. For the unstimulated Jurkat cells, where the pTyr events rarely occurred, it identified 343 high confident pTyr sites from 5 mg of proteins, which was 31% more than that obtained by the antibody-based method. For the heterogeneous sample of tissue, it identified 197 high confident pTyr sites from 5 mg protein digest of mouse skeletal muscle. In general, it is a sensitive, robust and cost-effective approach and would have wide applications in the study of the regulatory role of tyrosine phosphorylation in diverse physiological and pathological processes.

How the Monte Carlo production of a wide variety of different samples is centrally handled in the LHCb experiment

In the LHCb experiment a wide variety of Monte Carlo simulated samples needs to be produced for the experiment's physics program. Monte Carlo productions are handled centrally similarly to all massive processing of data in the experiment. In order to cope with the large set of different types of simulation samples, necessary procedures based on common infrastructures have been set up with a numerical event type identification code used throughout. The various elements in the procedure, from writing a configuration for an event type to deploying them on the production environment, from submitting and processing a request to retrieving the sample produced as well as the conventions established to allow their interplay will be described. The choices made have allowed a high level of automation of Monte Carlo productions that are handled centrally in a transparent way with experts concentrating on their specific tasks. As a result the massive Monte Carlo production of the experiment is efficiently processed on a world-wide distributed system with minimal manpower.

Development and Validation of a Novel Lateral Flow Immunoassay (LFIA) for the Rapid Screening of Paralytic Shellfish Toxins (PSTs) from Shellfish Extracts.

A single-step lateral flow immunoassay (LFIA) was developed and validated for the rapid screening of paralytic shellfish toxins (PSTs) from a variety of shellfish species, at concentrations relevant to regulatory limits of 800 μg STX-diHCl equivalents/kg shellfish meat. A simple aqueous extraction protocol was performed within several minutes from sample homogenate. The qualitative result was generated after a 5 min run time using a portable reader which removed subjectivity from data interpretation. The test was designed to generate noncompliant results with samples containing approximately 800 μg of STX-diHCl/kg. The cross-reactivities in relation to STX, expressed as mean ± SD, were as follows: NEO: 128.9% ± 29%; GTX1&4: 5.7% ± 1.5%; GTX2&3: 23.4% ± 10.4%; dcSTX: 55.6% ± 10.9%; dcNEO: 28.0% ± 8.9%; dcGTX2&3: 8.3% ± 2.7%; C1&C2: 3.1% ± 1.2%; GTX5: 23.3% ± 14.4% (n = 5 LFIA lots). There were no indications of matrix effects from the different samples evaluated (mussels, scallops, oysters, clams, cockles) nor interference from other shellfish toxins (domoic acid, okadaic acid group). Naturally contaminated sample evaluations showed no false negative results were generated from a variety of different samples and profiles (n = 23), in comparison to reference methods (MBA method 959.08, LC-FD method 2005.06). External laboratory evaluations of naturally contaminated samples (n = 39) indicated good correlation with reference methods (MBA, LC-FD). This is the first LFIA which has been shown, through rigorous validation, to have the ability to detect most major PSTs in a reliable manner and will be a huge benefit to both industry and regulators, who need to perform rapid and reliable testing to ensure shellfish are safe to eat.

Statistical notes for clinical researchers: Type I and type II errors in statistical decision.

Statistical inference is a procedure that we try to make a decision about a population by using information from a sample which is a part of it. In modern statistics it is assumed that we never know about a population, and there is always a possibility to make errors. Theoretically a sample statistic may have values in a wide range because we may select a variety of different samples, which is called a sampling variation. To get practically meaningful inference we preset a certain level of error. In statistical inference we presume two types of error, type I and type II errors.

Determining the presence of chicken and turkey meat in selected meat products using realtime PCR method

The one of the most convenient method for the identification of animal species in raw and processed meat products is the examination of DNA sequences. Real-Time PCR are particularly suitable because even small fragments of DNA formed during heat processing of the meat can be amplified and identified. TaqMan Real-Time PCR is a rapid, convenient and sensitive assay for meat identification. For chicken and turkey meat identification we were using species-specific primers and TaqMan probe designed on the mitochondrial cytochrome b. The intensity of the fluorescence signal has risen at a variety of different samples. We analysed sixteen the samples of turkey meat products and we found the incidence of chicken at nine samples in the range of the detection range of the reaction0.1 to 100%. Sample 8 fluorescence intensity exceeded the detection threshold in the 22.11 cycle (Cp = 22.11); Sample 6, (Cp = 23.19); Sample 1 in 27.08 cycle (Cp = 27.08); Sample 7 in 31,7 cycle (Cp = 31.7) and sample 5 in 32.32 cycle (Cp = 32.32). All Cp values for these samples fluorescence intensity exceeded the detection threshold in earlier cycles as sample the 100% turkey DNA. It follows that in the samples no. 8, 6, 1, 5, and 7 is in the range of chicken DNA detection range of the reaction, from 0.1 to 100%. Sample 11 in the cycle 27,08 (Cp = 27.08); Sample 10 in the cycle 27.8 (Cp = 27.8); sample 16 in 28.03 cycle (Cp = 28.03) and sample 13 in the cycle of 29.18 (Cp = 29.18). In recognition of the results of the monitoring of the content of chicken meat in meat products it is appropriate to further verification and testing detection kits used to work for possible use in practice since it has been found to be sufficient sensitivity and specificity to 30 cycle reaction.

Extraction and separation of proteins by ionic liquid aqueous two-phase system

A satisfactory protocol of protein extraction and separation has been established based on the ionic liquid aqueous two-phase system (IL-ATPS) for the purification of bioactive substances. Compared with the effects of eight different ionic liquids, 1-octyl-3-methylimidazolium bromide ([omim][Br]) was selected as the suitable ionic liquid. Based on the single-factor experiment, an initial serial investigative test was used to identify the optimal conditions of the extraction. Owing to their different isoelectric points, bovine serum albumin (BSA), hemoglobin (Hb) and lysozyme (Lys) were used to determine the effect of pH value on the protein extraction. Trypsin (Try) was used to confirm the protein activity. The linearity for analyzing BSA, Hb, Try and Lys was in the concentration range of 0.05-1.00 mgml(-1), 0.025-1 mgml(-1), 0.01-1.00 mgml(-1) and 0.01-1.00 mgml(-1), respectively, with a correlation coefficient of between 0.9985 and 0.9999. Limits of detection (LODs) were 16.47-7.02 μgml(-1) and RSDs of inter-day stability were less than 2.9%. Repeatability and precision were respectively lower than 5.3% and 1.1%. Under the optimum conditions, the average recoveries of BSA, Hb, Try and Lys were 90.5%, 94.5%, 92.7% and 93.8% and the obtained RSDs were 1.19%, 1.23%, 1.34% and 1.04%, respectively. According to UV spectra, conductivity, dynamic light scattering (DLS), and transmission electron microscope (TEM) images, the cluster phenomenon originating from IL itself or combined with protein was evaluated. As the driving forces which are involved in the partitioning of protein between the IL-rich phase and the phosphate phase, the cluster phenomenon could, in principle, be applied to a variety of different samples and exhibited potential value.

DeepQuanTR: MALDI-MS-based label-free quantification of proteins in complex biological samples

The quantification of changes in protein abundance in complex biological specimens is essential for proteomic studies in basic and applied research. Here we report on the development and validation of the DeepQuanTR software for identification and quantification of differentially expressed proteins using LC-MALDI-MS. Following enzymatic digestion, HPLC peptide separation and normalization of MALDI-MS signal intensities to the ones of internal standards, the software extracts peptide features, adjusts differences in HPLC retention times and performs a relative quantification of features. The annotation of multiple peptides to the corresponding parent protein allows the definition of a Protein Quant Value, which is related to protein abundance and which allows inter-sample comparisons. The performance of DeepQuanTR was evaluated by analyzing 24 samples deriving from human serum spiked with different amounts of four proteins and eight complex samples of vascular proteins, derived from surgically resected human kidneys with cancer following ex vivo perfusion with a reactive ester biotin derivative. The identification and experimental validation of proteins, which were differentially regulated in cancerous lesions as compared with normal kidney, was used to demonstrate the power of DeepQuanTR. This software, which can easily be used with established proteomic methodologies, facilitates the relative quantification of proteins derived from a wide variety of different samples.

The 0.7 anomaly in one-dimensional hole quantum wires

In this paper we study the anomalous 0.7 structure in high quality ballisticone-dimensional hole systems. Hole systems are of interest because oftheir large effective mass, strong spin–orbit coupling, as well as havingspin 3/2 comparedto spin 1/2 for electrons. We observe remarkably clean conductance quantizationin a variety of different samples, and a strong feature at∼0.7 × 2e2/h, which shows a similar temperature and density dependence to the 0.7 feature observed inelectron systems. In contrast to the case for electrons, the strong spin–orbit coupling resultsin an anisotropic Zeeman splitting, which we use to probe the 0.7 feature and theassociated zero-bias anomaly. Our results indicate that the 0.7 feature and the zero-biasanomaly are related, and both are suppressed by spin polarization. These resultsplace valuable constraints on models of the microscopic origins of the 0.7 feature.

An apparatus for imaging liquids, cells, and other wet samples in the scanning electron microscopy

We present a technique of scanning electron microscopy that is adapted to the study of wet samples. The wet environment is protected in a small chamber enclosed by a membrane, which is thin enough for energetic electrons to go through and interact with the sample studied. We detail both the technique and the general mechanisms of signal formation in the imaging of samples through a membrane. We first describe our setup and the properties required for the membrane, the main element in this method. Some simple measurements for its characterization are given, guiding the choice of material and thickness. We then go on to describe the capabilities of the technique in imaging a variety of different samples. We evaluate the accessible contrast and resolution, and the current needed to obtain them. Low contrast samples can be imaged with an improvement in resolution over optical microscopy. High contrast samples like gold markers labeling a biological cell can be imaged with a resolution of the order of 10 nm. The resolution depends on the location of the particle in the sample: the closer to the membrane, the better the resolution. We believe such a result opens up potential applications for routine experiments in biology, and expect this new technique to find numerous applications in domains where liquid samples are investigated such as soft materials science.

The multidisciplinarity of spectromicroscopy: from geomicrobiology to archaeology

Abstract Synchrotron X-ray PhotoElectron Emission Microscopy (X-PEEM) is a useful tool to investigate the microchemical composition of a variety of different samples, including cells in culture, tissue sections, magnetic material, bacteria, rocks, materials science, tribology and archaeology specimens. The MEPHISTO X-PEEM, installed at the Wisconsin Synchrotron Radiation Center, reached a peak resolution of 20 nm, has been extensively used for the last 4 years to explore all of the above systems. The experiments reported here are some of the most unusual ones for this technique: ZnS precipitating bacteria, Mn and Fe oxide rocks and archaeological coins. The microchemistry of each one of these samples delivered new results.

Determination of Dissolved and Adsorbed EDTA Species in Water and Sediments by HPLC

This paper describes a method for determining EDTA species in various environmental samples at low molar concentrations by high-performance liquid chromatography (HPLC). Distinction between Fe(III)EDTA and all the other species can be made. NiEDTA can be detected semiquantitatively. The fraction of EDTA adsorbed to suspended particles or to sediments can be determined after desorption with phosphate. After complexation with Fe(III), the EDTA is detected by reversed-phase ion-pair liquid chromatography as the Fe(III)EDTA complex at a wavelength of 258 nm. The behavior of a variety of metal-EDTA complexes during analysis was checked. Determination of different EDTA species (Fe(III)EDTA, NiEDTA, and adsorbed EDTA) is possible in river water, groundwater, and effluents from wastewater treatment plants. Fe(III)EDTA was found to be the main species, at 30-70%; NiEDTA was <10% in most of the samples. Adsorbed EDTA was detected in suspended particles from rivers and wastewater treatment plants and in sediment cores from a lake. The method is suitable for a variety of different samples with different concentration ranges.

Mechanisms limiting the d.c. conductivity of high-conductivity polyacetylene

For a variety of different samples of stretch-aligned Naarmann polyacetylene, highly doped with iodine, the temperature dependence of the anisotropic d.c. conductivity (σ) has been examined. We find room temperature values of σ t varying from 3500 S/cm to more than 10 000S/cm. For all samples investigated, σ( T) can be fitted with the Sheng formula and evaluated within a phenomenological model assuming potential barriers between separate highly conducting regions, yielding similar barrier heights (9 – 13 meV) and widths (1.5 – 1.7 nm) for different samples. It is shown that the room-temperature conductivity of high-σ polyacetylene is determined mainly by the resistivity of the highly conducting regions, whereas the barriers limit the conductivity at lower temperatures. A comparison of high-σ and low-σ samples indicates that phonon scattering does not contribute significantly to the resistivity at room temperature.

The kinetics of the solid state transformation of racemic to optically active 1,1′-binaphthyl

Rates of the solid state reaction which thermally converts racemic to optically active 1,1′-binaphthyl (mp 158 °C) have been determined at temperatures between 105 and 135 °C using polycrystalline samples. The presence of a sufficiently uniform distribution of enantiomorphic seed crystals results in a smooth conversion of the racemate to the eutectic crystal forms of binaphthyl. Although it is possible to force the resolution reaction almost to completion at higher temperatures (150 °C) where the melt phase is an intermediate, lower final specific rotations are obtained when only solid phases are involved (below 145 °C) because of the independent nucleation of racemic material from the reacting crystals. Both spontaneous nucleation and reaction rates in the solid state were increased by grinding the initially prepared samples and were decreased by the storage of samples. The Arrhenius activation energy of this phase transformation giving optically active product is ca. 60 kcal/mol in a variety of different samples. This is consistent with a mechanism in which a molecule of 1,1′-binaphthyl attains considerable freedom from the racemic solid in order to interconvert to its enantiomer and add to the growing optically active phase.

Automated Analysis of Alcohols in Blood

Abstract Gas chromatography is a valuable analytical tool for the measurement of volatiles in a variety of different samples. Published methods utilizing this technique for the analysis of ethanol and related volatiles in blood and urine are now too numerous to mention. However, in a recent publication by Jain, a simple, rapid gas chromatographic method for the simultaneous determination of methanol, ethanol, acetone, isopropanol, as well as low boiling hydrocarbons associated with glue sniffing was described. The method involves the direct injection of blood mixed with an internal standard. Jain reported the successful use of his G.C. column for more than two years and several thousand injections.