Set Of Columns Research Articles

Validation of bioanalytical method for quantification of Vitamin K2 (MK-4) in human plasma by high-performance liquid chromatography-ultraviolet.

Vitamin K can reduce warfarin's anticoagulant action, causing a variance in response among individuals taking warfarin. Vitamin K comes in two forms, namely Vitamin K1 (phylloquinone) and K2 (menaquinones). Menaquinone-4 (MK-4) is a kind of Vitamin K2 found in meat and dairy products. Analysis of MK-4 levels in human plasma is very useful for patients who receive warfarin therapy. High-performance liquid chromatography (HPLC) can be used for warfarin's bioanalysis, and it must be validated. The purpose of this study was to validate the bioanalytical method for quantification of Vitamin K2 (MK-4) in human plasma according to the 2019 European Medicines Agency (EMA) guideline. Vitamin K2 (MK-4) was extracted using acetonitrile. HPLC with an ultraviolet detector at 245 nm, using a T3 column set at 30°C and an isocratic mobile phase containing methanol: phosphate buffer (95:5) at pH 3, a flow rate of 1 mL/min was used in this study. The warfarin concentration of 0.5-3 µg/mL was used. About 5.50%-17.42% and 6.18%-8.74%, respectively, were the average ranges of percentage coefficient of variation and percentage difference. There was no response at the analyte's retention time in the six blank plasmas and at the analyte's retention time in the blank after the injection of upper limit of quantification, indicates that the procedure was very selective and did not result in any carryover. This bioanalytical method fulfills the parameters of selectivity, accuracy, precision, and carryover based on the 2019 EMA guidelines.

Defining a generic column set for achiral supercritical fluid chromatography applied to pharmaceuticals or natural products

When starting a method development in supercritical fluid chromatography (SFC), the first step is usually to screen several stationary phases based on previous experience or simply based on what is available in the laboratory. However, as there are now a large number of stationary phases available for SFC, the choice of an adequate set of columns to rapidly achieve a satisfying result can be difficult. In this project, 16 columns comprising a wide diversity of stationary phases and polarities ranging from the most polar (like bare silica gel) to the least polar (like octadecylbonded-silica) were compared, based on the gradient analysis of 129 probe compounds. The set mostly comprised active pharmaceutical ingredients, natural products and a few metabolites. The columns were ranked with the help of Derringer desirability functions taking account of (i) the number of compounds eluted from the column, (ii) the elution time in a suitable time frame, (iii) the average peak width, (iv) the average peak symmetry and (v) the spreading of retention along the gradient time. The five criteria selected showed no correlation. Overall, it appeared that those columns that had a high overall score were good for several reasons, like bare silica gel, propanediol-bonded silica or pentabromobenzyloxy-bonded silica. Initially, the columns had been screened with a gradient elution starting from 5% co-solvent and ending with 50% co-solvent in CO2. However, for some most retentive columns like amide-bonded silica, too many compounds remained non-eluted from the column. To examine this column more fairly, a second elution gradient was applied that ended with 100% co-solvent. This proved effective in restoring good overall performance through the elution of the most polar compounds.

Impact of Process Poisons on the Performance of Post‐Phthalate Supported Ziegler–Natta Catalysts in Gas Phase Propylene Polymerization

AbstractThe impact of common process catalyst poisons on the performance of a 6th generation Ziegler–Natta catalysts during the gas phase polymerization of propylene are examined using two approaches: introducing propylene without purification, or with one or two sets of purification columns, and by introducing carbon dioxide (CO2), oxygen (O2), water (H2O), methanol (CH3OH), ethyl acetate (C4H8O2) and dimethyl sulfoxide (C2H6SO) during the polymerization. As expected, purification columns increases the catalyst activity significantly, slightly reduce catalyst decay. Injecting TiBA during the reaction leads to an activity increase. The addition of two full sets of columns substantially increased the repeatability of polymerization reactions. The power of deactivation of poisons injected during the polymerization reaction is: O2 > CO2 > CH3OH > C2H6SO > C4H8O2 > H2O. Adding CO2, O2, and CH3OH resulted in a progressive decrease in molecular weight while almost no effect is observed with H2O. However, C4H8O2, and C2H6SO resulted in a mild increase in molecular weight. Additionally, the effects on crystallinity and stereoregularity are similar where CO2, O2, H2O and CH3OH caused a progressive decrease while C4H8O2 and C2H6SO resulted in a mild increase, indicating some isotacticity control by these two poisons.

Design of diamond drill heads with a hydrojet effect of rock destruction

It follows from the analysis of materials related to the design and operation of drilling equipment that an important direction in the search for effective solutions appears to be the improvement of the structure of the working matrix of diamond drilling heads and the enhancement of their technological capabilities by using in their schemes physical effects that are unconventional in the field of well drilling technology. The tasks to be solved are to reduce the energy costs of the process of deepening wells, to obtain a structurally integral, informative core, and to ensure the stability of well walls. Following the concept, diamond drill heads with a separate system of washing channels and a hydrojet effect of rock destruction were designed and tested during the drilling of wells. The novelty of the structure of drill heads is the direction of the pressure flow of liquid to the steps of the bottom of the wells, repeating the shape of the matrix, the removal of sludge along the grooves and radial grooves, the treatment of the well wall. A special technology for the manufacture of diamond drill heads with a complex geometry of the matrix has been devised. The performance of diamond drill heads of various designs was tested under the industrial conditions of drilling wells for water and at polymetal deposits. It has been established that in terms of the quality of the tasks to be solved and technical and economic indicators, they have a significant advantage in comparison with standard equipment in terms of the mechanical speed of drilling wells, energy costs, and structural integrity of the core. The comparative states of the shape, the transverse size of the hydrogeological well, the purity of the treatment of the wall of the latter, drilled by diamond drill heads and standard equipment with ball bits, are indicative. The structural integrity of the core selected by the regular column set HQ in an assembly with drill heads with a hydrojet effect of rock destruction is ensured

Experimental and numerical study on seismic performance of precast segmental CFST bridge columns with non-uniform prestressed steel tendons

A precast segmental concrete-filled steel tube (PSCFST) bridge column set with non-uniform (external and internal) prestressed post-tensioned (PT) steel strands was proposed, then the seismic performance of this type of bridge column was researched in this paper. The external prestressed steel strands are arranged on the outside of the bridge column to provide re-centering force, which can facilitate to observe the damage state of the PT tendons and be rapidly replaced. Pseudo static test was carried out on three scaled specimens, including a reference monolithic reinforced concrete (MRC) column and two PSCFST columns. The test results showed that both PSCFST columns have good seismic and resilience performance, with no visible damage and little residual displacement. The PSCFST column with external and internal PT strands shows better self-centering performance. The external prestressed steel strand will yield earlier than the internal, so it can be used as an early damage warning device for the PSCFST column. Then, a detailed finite-element (FE) model was established and validated using the test specimen. The finite element calculation results are in good agreement with the experimental results, indicating that good applicability of the established FE model. Furthermore, based on the validated FE model, the non-uniform arrangement position and initial prestress level of the prestressed PT steel strand were analyzed. That is, analysis was conducted to investigate the seismic and resilience behaviors of the PSCFST specimen with different arrangements of PT strands and different ratios of initial prestress of the internal and external PT strands. Analytical results indicated that increasing the initial prestress value of the external steel strand can increase the bearing capacity of the PSCFST specimens, while the initial prestress of the external prestressed steel strand has little effect on the initial stiffness, drift ratio, or accumulative energy dissipation. Furthermore, allocating more external PT strands can increase the bearing capacity and initial stiffness of the PSCFST specimen, while decreasing the drift ratio.

Grammic monoids with three generators

Young tableaux are combinatorial objects whose construction can be achieved from words over a finite alphabet by row or column insertion as shown by Schensted sixty years ago. Recently Abram and Reutenauer studied the action of the free monoid on the set of columns defined by the famous insertion algorithm. Since the number of columns is finite, this action yields a finite transformation monoid. Here we consider the action on the set of rows. We investigate the corresponding infinite monoid in the case of a 3 letter alphabet. In particular we show that it is the quotient of the free monoid relative to a congruence generated by the classical Knuth rules plus a unique extra rule.

Interdigitated Columnar Representation of Personal Space and Visual Space in Human Parietal Cortex.

Personal space (PS) is the space around the body that people prefer to maintain between themselves and unfamiliar others. Intrusion into personal space evokes discomfort and an urge to move away. Physiologic studies in nonhuman primates suggest that defensive responses to intruding stimuli involve the parietal cortex. We hypothesized that the spatial encoding of interpersonal distance is initially transformed from purely sensory to more egocentric mapping within human parietal cortex. This hypothesis was tested using 7 Tesla (7T) fMRI at high spatial resolution (1.1 mm isotropic), in seven subjects (four females, three males). In response to visual stimuli presented at a range of virtual distances, we found two categories of distance encoding in two corresponding radially-extending columns of activity within parietal cortex. One set of columns (P columns) responded selectively to moving and stationary face images presented at virtual distances that were nearer (but not farther) than each subject's behaviorally-defined personal space boundary. In most P columns, BOLD response amplitudes increased monotonically and nonlinearly with increasing virtual face proximity. In the remaining P columns, BOLD responses decreased with increasing proximity. A second set of parietal columns (D columns) responded selectively to disparity-based distance cues (near or far) in random dot stimuli, similar to disparity-selective columns described previously in occipital cortex. Critically, in parietal cortex, P columns were topographically interdigitated (nonoverlapping) with D columns. These results suggest that visual spatial information is transformed from visual to body-centered (or person-centered) dimensions in multiple local sites within human parietal cortex.SIGNIFICANCE STATEMENT Recent COVID-related social distancing practices highlight the need to better understand brain mechanisms which regulate "personal space" (PS), which is defined by the closest interpersonal distance that is comfortable for an individual. Using high spatial resolution brain imaging, we tested whether a map of external space is transformed from purely visual (3D-based) information to a more egocentric map (related to personal space) in human parietal cortex. We confirmed this transformation and further showed that it was mediated by two mutually segregated sets of columns: one which encoded interpersonal distance and another that encoded visual distance. These results suggest that the cortical transformation of sensory-centered to person-centered encoding of space near the body involves short-range communication across interdigitated columns within parietal cortex.

Evaluation of Gas Chromatography Columns with Radially Elongated Pillars as Second-Dimension Columns in Comprehensive Two-Dimensional Gas Chromatography.

The present study investigated the use of a dedicated gas chromatography (GC) column (L = 70 cm, 75 μm deep, and 6.195 mm wide) with radially elongated pillars (REPs) as the second column in a comprehensive two-dimensional gas chromatography (GC × μGC) system. Three stationary phases [apolar polydimethylsiloxane (PDMS), medium polar room-temperature ionic liquid (RTIL) based on monocationic phosphonium, and polar polyethylene glycol (PEG-1000)] have been coated using the static method at constant pressure or using an original vacuum pressure program (VPP) from 400 to 4 mbar. The best efficiency reached up to N = 62,000 theoretical plates for a film thickness of 47 nm at 100 °C for an iso-octane peak (k = 0.16) at an optimal flow rate of 4.8 mL/min. The use of the VPP improved the efficiency by approximately 15%. Efficiencies up to 28,000 and 47,000 were obtained for PEG-1000 and RTIL, respectively. A temperature-programmed separation of a mixture of 11 volatile compounds on a PDMS-coated chip was obtained in less than 36 s. The PDMS-, PEG-1000-, and RTIL-coated chips were tested as the second column using a microfluidic reverse fill/flush flow modulator in a GC × μGC system. The REP columns were highly compatible with the operating conditions in terms of flow rate and with more than 30,000 plates for the iso-octane peak. Moreover, a commercial solvent called white spirit containing alkanes and aromatic compounds was injected in three sets of columns in normal and reverse modes, demonstrating the great potential of the chip as a second-dimension separation column.

Evaluating bioretention scale effect on stormwater retention and pollutant removal.

Bioretention column studies are commonly used in laboratory to assess the performance of such structures in removal of pollutants and to investigate different conceptions aiming to increase their efficiency. However, no studies were found recommending suitable diameters or sizes, or about the uncertainties related to the transfer of results among the different scales (i.e., among different experiments or from the laboratory to field scale). This study assessed the effect of the varying diameters in experimental bioretention columns on the retention and removal of pollutants from stormwater runoff. Three sets of columns with diameters of 400mm, 300mm, and 200mm were assessed. The results showed that runoff retention (R) was affected by the time interval between stormwater events, but not by the bioretention diameter, although the diameter influenced the variability of R results. The removal of TSS (95%), nitrite (98%), and phosphate (96%) did present variability among the different bioretention diameters. However, the nitrate removal was statistically different among the bioretention columns, with removal efficiency above 50% in the 300-mm and 200-mm columns, while the 400-mm columns acted as a source of nitrate by increasing its concentration in the outflow stormwater by up to 285%, suggesting that the removal of this pollutant can be influenced by the scale effect of the bioretention columns and the experiments with small bioretention diameters may not provide reliable results.

Determining haloacetic acids in drinking water by one-pump column-switching ion chromatography: An online and cost-effective tool for matrix removal and sample enrichment

Haloacetic acids (HAAs) are a group of disinfection byproducts ubiquitously found in disinfected drinking water and they are currently regulated by some governments. Conventional HAAs analytic methods employ either gas chromatography (GC), two-dimensional ion chromatography (2D-IC), or ion chromatography with electrospray ionization tandem mass spectrometry (IC-ESI-MS/MS) to reduce the effect of interfering compounds and enhance detection resolution; however, they are either laborious in sample preparation procedures or too expensive to be used by common laboratories. To bypass these problems, this study proposes to analyze HAAs by employing a one-pump column-switching ion chromatography (OPCS-IC) that allows direct sample injection without requiring extraction and derivatization pretreatments. Unlike 2D-IC method, which uses two pumps and two parallel sets of IC columns, this method applies only one pump and one column. The tailored OPCS-IC removes coexisting anions from water and enriches HAAs simultaneously, thereby distinguishing HAAs from interfering anions and magnifying the signals of HAAs. For example, when HAAs were enriched by five times, the coexisting F−, Cl−, Br−, NO3–, and SO42− were removed by 62.4%, 93.9%, 99.7%, 99.9%, and 98.9%, respectively. Meanwhile, the recoveries of HAAs dosed into real samples ranged from 84% to 102%, similar to those obtained from conventional GC method, meaning that the convenience of this method did not compromise its performance. The study hence proves an easy-to-use and relatively cheaper method for measuring HAAs in drinking water.

When Is a Graded Free Complex Exact?

Minimal free resolutions of a finitely generated module over a polynomial ring S=k[x], with variables x={x1,…,xn} and a field k have been extensively studied. Almost all the results in the literature about minimal free resolutions give their Betti numbers, that is, the ranks of the free modules in the resolution at each degree. Several techniques have been developed to compute Betti numbers, making this a manageable problem in many cases. However, a description of the differentials in the resolution is rarely given, as this turns out to be a more difficult problem. The main purpose of this article is to give a criterion to check when a graded free complex of an S-module is exact. Unlike previous similar criteria, this one allows us to give a description of the differentials using the combinatorics of the S-module. The criterion is given in terms of the Betti numbers of the resolutions in each degree and the set of columns of the matrix representation of the differentials. In the last section, and with the aim of illustrating how to use the criterion, we apply it to one of the first better-understood cases, the edge ideal of the complete graph. However, this criterion can be used to give an explicit description of the differentials of a resolution of several monomial ideals such as the duplication of an ideal, the edge ideal of a cograph, etc.

Small to medium strain dynamic properties of Lanzhou loess, China

Loess is a kind of world-recognized problematic soil and, as a consequence, it is a major hazard in geotechnical engineering. This study examines the small to medium strain dynamic properties of Lanzhou intact and recompacted loess through a set of resonant column (RC) tests. The influence of soil structure on the small-strain shear modulus G0, the variations of G/G0, and damping ratio DT(%) with shear strain γ were analyzed and discussed. The test results show that the structure has an important influence on the dynamic properties of dry loess at small and medium strain, whereas, with the increase of moisture, its effect weakens. It is proved that a normalized correlation between G/G0 and γ/γ0.7 is practically identical for undisturbed and recompacted loess in Lanzhou, irrespective of soil structure, which may be useful in practical applications.

“Missouree Was Always Out of Step with Missourah”

Language users can create moral geographies, in which values are mapped in space, by indexically linking values and spatial referents. One understudied aspect of linguistic practice in this domain is the role of toponyms in constructing a moral geography. This investigation illustrates how sociolinguistic variants of a toponym can be used to construct a moral geography. I take as a case study sociolinguistic variation in the US state name Missouri, which can be produced as Missouree or Missourah. Qualitative analysis of a set of local newspaper columns shows these variants can be used as place names. However, they do not distinguish regions of physical space. Rather, the variants label moral spaces by setting each variant on opposing ends of cultural, geographic, and political axes of contrast. Because their primary role is to label moral space, I suggest that toponymic studies should consider the kind of geography that a toponym labels space within. I consider the usage here to be examples of “moral toponyms”, in contrast to traditional toponyms which label physical space.

Reframing Tragedy

Reframing Tragedy

Flow-modulated comprehensive two-dimensional gas chromatography combined with time-of-flight mass spectrometry: use of hydrogen as a more sustainable alternative to helium.

The present research is focused on the use and evaluation of hydrogen, as a more sustainable alternative to helium, within the context of fast flow modulation comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry. In such a respect, a comparison was made between the two mobile phases in terms of speed and overall chromatography performance. All experiments were carried out by using the following column set: low polarity with dimensions 10m × 0.25mm ID × 0.25µm df and medium polarity with dimensions 2m × 0.10mm ID × 0.10µm df. Fundamental gas chromatography parameters (efficiency, resolution) were measured under different experimental conditions, using the two carrier gases. Efficiency was measured in both the first and second dimensions, using a probe compound under isothermal conditions; after defining the optimum carrier gas conditions, a mixture containing 20 pesticides was analyzed to measure resolution, again in the first and second dimensions, using a temperature program. It was found (as expected) that a similar chromatography performance could be attained when using hydrogen, albeit with a circa 25% reduction in analysis time. Signal-to-noise ratios of the pesticides were calculated, using both carrier gases, with such values generally reduced (on average by 14%) when using hydrogen. Finally, a comparison was made between mass spectral profiles obtained analyzing the pesticides and fatty acid methyl esters using the two mobile phases. Even though mass spectral differences were observed, the ion profiles could be considered generally similar.

Some Bayesian biclustering methods: Modeling and inference

AbstractStandard one‐way clustering methods form homogeneous groups in a set of objects. Biclustering (or, two‐way clustering) methods simultaneously cluster rows and columns of a rectangular data array in such a way that responses are homogeneous for all row‐cluster by column‐cluster cells. We propose a Bayes methodology for biclustering and corresponding MCMC algorithms. Our method not only identifies homogeneous biclusters, but also provides posterior probabilities that particular instances or features are clustered together. We further extend our proposal to address the biclustering problem under the commonly occurring situation of incomplete datasets. In addition to identifying homogeneous sets of rows and sets of columns, as in the complete data scenario, our approach also generates plausible predictions for missing/unobserved entries in the rectangular data array. Performances of our methodology are illustrated through simulation studies and applications to real datasets.

The citation analysis of the articles published in Chinese Journal of Otorhinolaryngology Head and Neck Surgery from 2009 to 2019

Objective: To analyze the citation of articles in Chinese Journal of Otorhinolaryngology Head and Neck Surgery, and to explore the strategy for running scientific journals. Methods: Using the Citation Database of Chinese Biomedical Journals, the citations of articles in this journal from 2009 to 2019 were statistically analyzed, and the characteristics of highly cited articles were analyzed. Results: From 2009 to 2019, Chinese Journal of Otorhinolaryngology Head and Neck Surgery published 2 814 papers. Cited papers accounted for 75.69% of all papers, and each paper was cited 7.24 times. The citation rate of published papers was consistent with the variation trend of citation frequency. Non treatises such as guide consensus and original articles for special issues were cited better. There was no obvious correlation between paper funding and citation. Conclusion: Improving the content quality and optimizing the column setting are important measures to enhance the influence of scientific journals.

Comparison of chromium mobility at naturally enriched and anthropogenically polluted sites: A column leaching experiment

This study aims to compare the chromium (Cr) mobility in two soils with different Cr sources. The first one is an anthropogenically contaminated soil from an area of a piston ring production factory, and the second one is a serpentine soil with a naturally increased Cr level from the National Nature Reserve Mohelno serpentine steppe in the Czech Republic. To assess the influence of naturally occurring environmental factors on the Cr mobility, two sets of column leaching experiments were constructed, namely an acidified water treatment (AW) and a simulated root exudate treatment (SRE). It was found that the anthropogenically contaminated soil leached out many times more Cr for both (the AW and SRE) treatments in comparison with the serpentine soil. Generally, all the samples showed enhanced leaching from the bottom layer, respectively the horizon, for both treatments. Only the anthropogenic soil showed some differences in the bottom layer, which was more susceptible to the AW treatment than to the SRE one. These findings show the high dependence of the leachability of Cr on the Cr content origin. It has been proven that naturally enriched sites where elevated levels of Cr originate from the bedrock are more resistant to Cr leaching than anthropogenically contaminated soils. Feasible causes of these differences are discussed in this study.

BIDIMENSIONAL LINKED MATRIX FACTORIZATION FOR PAN-OMICS PAN-CANCER ANALYSIS.

Several modern applications require the integration of multiple large data matrices that have shared rows and/or columns. For example, cancer studies that integrate multiple omics platforms across multiple types of cancer, pan-omics pan-cancer analysis, have extended our knowledge of molecular heterogeneity beyond what was observed in single tumor and single platform studies. However, these studies have been limited by available statistical methodology. We propose a flexible approach to the simultaneous factorization and decomposition of variation across such bidimensionally linked matrices, BIDIFAC+. BIDIFAC+ decomposes variation into a series of low-rank components that may be shared across any number of row sets (e.g., omics platforms) or column sets (e.g., cancer types). This builds on a growing literature for the factorization and decomposition of linked matrices which has primarily focused on multiple matrices that are linked in one dimension (rows or columns) only. Our objective function extends nuclear norm penalization, is motivated by random matrix theory, gives a unique decomposition under relatively mild conditions, and can be shown to give the mode of a Bayesian posterior distribution. We apply BIDIFAC+ to pan-omics pan-cancer data from TCGA, identifying shared and specific modes of variability across four different omics platforms and 29 different cancer types.

ANALYTICAL METHOD DEVELOPMENT AND VALIDATION OF CAPMATINIB IN BULK AND TABLET DOSAGE FORM BY RP-HPLC METHOD

An HPLC method was developed and validated for the estimation of Capmatinib in bulk and pharmaceutical dosage form. The chromatographic system was equipped Agilent column 150 mm x 4.6 mm internal diameter with 5 micron particle size column and UV detector set at 218nm, in conjunction with a mobile phase of Methanol and phosphate buffer PH 5 in the ratio of (65:35) at a flow rate of 0.5 ml/min. The retention time of capmatinib was found to be 4.3 minute. The separation was performed at ambient temperature. The injection volume was 10μl. Linearity in concentration range of 10-50μg mL with regression 0.999. The Percentage recoveries were found in the range of 101.4– 101.8%. The proposed method was validated in accordance with ICH parameters the method is precise, accurate, selective and rapid.