Set Of Columns Research Articles

Development, validation and clinical implementation of a UPLC-MS/MS bioanalytical method for simultaneous quantification of cabotegravir and rilpivirine E-isomer in human plasma

A reversed phase ultra-high performance liquid chromatography method was developed for the simultaneous quantification of cabotegravir (CAB) and the E-isomer of rilpivirine (RPV) in human EDTA plasma, also considering RPV E-isomer instability. Because of the instability of RPV (and CAB) in all light conditions, the (RPV Z-isomer/total RPV)-isomer ratio of RPV was determined for each stock, calibration curve standard, quality control sample and patient sample. [2H3]-CAB and [13C6]-RPV were used as internal standard. Sample preparation involved protein precipitation of plasma using methanol. An HSS T3 column with a guard column (set at 40 °C) was used for analyte separation. The mobile phase components were 65 % 0.1 % formic acid in water (A) and 35 % 0.1 % formic acid in acetonitrile (B) and the flow rate was 0.5 mL/min. Detection was performed with tandem mass spectrometry (MS/MS) in a total runtime of 3.0 min. The assay was validated over the concentration range of 0.0500 – 10.0 mg/L for CAB and 0.00300 – 3.00 mg/L for RPV. The average within-day and between-day accuracies for the assay in plasma were 101 % and 101 % for CAB and 97.6 % and 98.5 % voor RPV, respectively. Within-day and between-day precision in coefficients of variations (CV) were 5.0 %. Extraction recovery was 99 % and 102 % for CAB and its internal standard and 95 % and 97 % for RPV and its internal standard. As our aim was that the (Z-isomer RPV/total RPV) response ratio in patient samples had to be less than 10 % to give reliable results, the (Z-isomer RPV/total RPV) response ratio in stocks, calibration curve standards and internal quality control samples were also taken into account being maximal 0.9 % and 2.3 % respectively. This assay has been successfully used in our Therapeutic Drug Monitoring (TDM) service for people living with HIV on long-acting injectable therapy with CAB/RPV and will also be used in future pharmacokinetic studies.

Comparison of System Constants of Thermostable Polysiloxane Stationary Liquid Phases of Different Origins

The expansion of possible areas of use of modern gas chromatography is largely determined by the thermal stability of stationary liquid phases (SLP), which allows the separation of complex mixtures of high-boiling compounds. A way to increase the thermal stability of nonpolar and weakly polar polysiloxane SLPs is to introduce rigid fragments into the polysiloxane chain. Currently, there is an extensive set of columns with thermostable SLPs, which, in some cases, have the index “ms”. However, in most cases, the nature of these phases and the methods for preparing the columns are not disclosed. In this work, using the linear free energy relationship (LFER) model, we compared the selectivity of a number of proprietary columns with in-house columns in which the siloxane–silarylene phase and the column preparation methods themselves are known. Various types of intermolecular interactions are considered within the framework of the LFER model.

Passive remediation of mine waters from Parys Mountain (Wales): Laboratory column experiments

This study evaluates the effectiveness of dispersed alkaline substrate (DAS) technology to treat highly acidic and contaminated leachates from the oxidation of sulfide-rich mining wastes under wet temperate oceanic climate conditions. To address this issue, leachates from the abandoned mine at Parys Mountain (NW Wales) were passed through two sets of multistep columns filled with a mixture of a fine-grained alkaline reagent (i.e., limestone, MgO, or BaCO3) scattered in an inert matrix. The set of columns with the limestone-DAS plus MgO-DAS combination achieved a near total removal of Fe, Al, Zn, Cu, Mn, As, Co, Cd, and Ni. However, the elimination of SO4 was not significant (around 7%). The limestone-DAS plus BaCO3-DAS combination also achieved a high effectiveness for base metal/loids, allowing the removal of Fe, Al, Zn, Cu, As, and Cd with rates of nearly 100%. In addition, the system with the BaCO3-step had a higher effectiveness in eliminating SO4 (around 53%) than the combined treatment with the MgO-step. According to PHREEQC code calculations, the precipitation of oxy-hydroxy-sulfates (i.e., schwertmannite and basaluminite) and carbonate (i.e., malachite, hydrozincite and calcite) phases may have controlled the solubility of pollutants during the passive treatment. The chemical compositions of the treated waters complied with the threshold values defined by irrigation standards, except for Mn in the BaCO3-DAS output.

An adaptive error-correcting output codes algorithm based on gene expression programming and similarity measurement matrix

The multi-class classification task is one of the most common tasks in machine learning. As a typical solution based on a partitioning strategy, Error-Correcting Output Codes (ECOC) can transform a multi-class classification problem into multiple binary classification problems. The key of ECOC is to construct an effective codematrix to represent a set of class decomposition schemes, which transforms a multiclass problem into a group of binary class problems. Consequently, the design of a fast and effective ECOC codematrix generation method is of great research significance and value for solving multi-class classification problems. In ECOC algorithms, the design of codematrix is treated as a combination problem between different code columns, in which the evolutionary algorithm shows a great advantage. Based on this consideration, the Gene Expression Programming (GEP) is applied to search for the codematrix with high performance because its expressive tree structure makes it well represent codematrcies for subsequent optimization operations. This paper proposes an adaptive ECOC algorithm based on Gene Expression Programming (GEP) and similarity measurement matrix, named GEP-ECOC. In our GEP, each individual represents a set of columns to form a random ECOC codematrix, which is optimized in the evolutionary process. Meanwhile, the crossover and mutation operations are modified to include a legality checking process to ensure that the generated codematrix satisfies the ECOC constraints. The GEP-based ECOC codematrix generation algorithm can quickly produce a codematrix with better performance, which ensures the efficiency of the algorithm to a certain extent. In addition, an adaptive algorithm based on a similarity measurement matrix is proposed to add new columns to the current codematrix, aiming to better handle hard classes. Our algorithm is compared with other algorithms on various data sets, and the experimental results confirm that our GEP-ECOC can balance the efficiency and performance of the algorithm and achieve higher performance.

Bentonite buffer under high temperature: laboratory experiments and coupled process modeling

Abstract. Bentonite buffer in a geological repository will be simultaneously heated from decaying radioactive waste and hydrated from the surrounding host rock, triggering complex and coupled THMC (thermal–hydrological–mechanical–chemical) processes. Understanding the THMC behavior of bentonite-based engineered barrier system (EBS) is key to the evaluation and prediction of its long-term performance. Studies on the THMC process have been focused on conditions under 100 ∘C, as most design concepts impose a thermal limit of 100 ∘C in bentonite. Recently, studies under high-temperature conditions have been conducted to evaluate the possibility of raising the thermal limit and expanding the data/knowledge base to increase the confidence level. In this abstract, we present a series of bench-scale laboratory experiments at high temperatures (up to 200 ∘C) and the corresponding modeling work. Two sets of column tests were conducted, and each set consisted of two test columns: a control column undergoing only hydration (non-heated) and an experiment column experiencing both heating and hydration (heated). During the experiment, frequent X-ray computed tomography (CT) images were collected to provide a 3D visualization of the density distribution and present the spatiotemporal evolution of (1) hydration/dehydration, (2) clay swelling/shrinkage, (3) displacement, and (4) mineral precipitation. The two sets of tests differ with respect to several experimental conditions, such as bentonite type, compacted density and water content, water chemistry, and hydration pressure, but the important difference is that the first set used bentonite powder with a dry density of 1.28 g cm−3, whereas the second set used granulated bentonite (mixture of pellets and powder) with a dry density of 1.45–1.5 g cm−3. In both sets of experiments, a comprehensive post-dismantling characterization of bentonite samples was carried out after the column tests had been running for 1.5 years. Comparing non-heated and heated columns, the temperature gradient led to lower degree of homogenization of bentonite after bentonite became fully saturated; comparing the first and second sets, granulated and powdered bentonite exhibited drastically different hydration behavior. A THM model with a 2D axisymmetric grid system was used to interpret the data from the first set of tests. The model considers the combined impact of saturation, fluid pressure, and porosity change due to swelling/compression on the spatiotemporal distribution of bulk density and movement of the thermocouple modules. Observations from the tests help us understand the early perturbation of bentonite buffer under high temperature, and data from these tests improve the calibration of key constitutive hydrological and mechanical models and, therefore, enhance the modeling capability with respect to calculating the long-term evolution of bentonite buffer.

Are You Ready to Switch to Comprehensive Two-Dimensional Gas Chromatography?

In the past two decades, comprehensive two-dimensional gas chromatography (GC×GC) has progressed from an interesting concept to the forefront of thinking and research in gas chromatography. Especially when combined with mass spectrometry detection, GC×GC provides high resolution, high sensitivity, and massive chromatographic data sets, which is useful in diverse fields such as petroleum analysis, metabolomics, food, flavor, fragrance, and environmental analysis. In this installment, recent developments in GC×GC that make it more amenable for routine use are discussed. These include advances in instrumentation, especially modulation, column sets, data analysis, and the range and types of samples amenable to GC×GC. We will ponder the question – are you ready to make the switch to GC×GC?

Economic assessment of corrosion prevention measures in new structures

AbstractChloride‐induced corrosion is a main cause of deterioration in reinforced concrete (RC). The premature deterioration of RC leads to unplanned repairs, hence elevating the direct and indirect costs of the RC infrastructure. The current prescriptive durability design approach has proven to be insufficient in assuring the durability of the RC exposed to chlorides. The objective of this study is an economical evaluation of several prevention measures for chloride‐induced corrosion following the performance‐based approach. A case study is inspired by a real set of RC columns, which suffered from chloride‐induced corrosion damage after 14 years in service. The considered prevention measures are the use of different binder systems, variation of the water/binder ratio, and changes in the concrete cover. To compare the obtained results, a reference design is set with a concrete mix and a cover thickness according to the requirements of the prescriptive approach described in the European standards. The results show that a balance between the binder type, concrete cover and water/binder ratio is necessary in order to optimize the costs while assuring the durability of the RC element.

Structural Assessment of a Water Reservoir Masonry Vaulted Roof from the Nineteenth Century

This article presents an experimental and numerical study on the structural safety of an old buried water reservoir built in the second half of the nineteenth century. The main goal of the study was to assess the feasibility of changing the reservoir roof from a garden with limited access to an outdoor exhibition or concert area, with an increase in service loads. The reservoir comprises a set of cylindrical vaults, built with rubble masonry and lime mortar, supported by a set of stone masonry arches and columns. Because no original design elements exist, the following methodology was followed: (1) a structural survey was first carried out for geometrical and material identification and for assessment of anomalies; (2) core samples were extracted from the vaulted roof to characterize the material properties of the rubble masonry and lime mortar; (3) a three-dimensional (3D) nonlinear finite element (FE) model of the structure was developed and used for structural safety verification; and (4) an in-situ static load test was carried out, in which the roof was subjected to a uniformly distributed load for assessment of its structural response and to validate the results from the numerical model. Overall, this study showed that the vaulted roof of the water reservoir has sufficient load capacity for its future use. Moreover, this work illustrates the application of a comprehensive methodology to assess the structural safety of a historical and very particular type of construction.

DETERMINATION OF THE CONDITIONS FOR THE IMPLEMENTATION OF THE DEFORMED DRILLING LAYOUT ROTATION IN THE MODE OF STABILIZATION OF THE BOREHOLE DIRECTION

Link for citation: Buglov N.A., Pushmin P.S. Determination of the conditions for the implementation of the deformed drilling layout rotation in the mode of stabilization of the borehole direction. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 7, рр.17-25.In Rus. The relevance of the study is caused by the need to create a general methodology for determining the eccentricity of the inertia center of the core set cross-section, which will significantly reduce the irrational material and energy costs of drilling wells drilled in conditions of natural curvature of their trunks, as well as optimize the technical and economic indicators of drilling operations. Objective: to increase the productivity of geological exploration when working in conditions of natural curvature of boreholes. Objects: drilling well, column set, drilling shell, drill string, natural curvature of the borehole, the trajectory of the borehole. Methods: analysis of literature sources on the research topic; processing data of production organizations; graphoanalytic method. Results. To eliminate some of the shortcomings currently available in the issue of maintaining the trajectory of the borehole drilled in conditions of natural curvature, a general technique is proposed that ensures minimization of the deflecting force on the rock-breaking tool during the deepening. The proposed technique is divided into two components: the use of pre-deformed core sets; the creation of a direct precession with continuous contact of the half-wave crest with the well wall during rotation of the arrangement. To implement the first case, the paper presents a method for determining the value of residual or preliminary deformation of a rectilinear core pipe. Practically, the proposed technique is implemented by sequentially performing three basic operations: the plane of deformation of the core set is determined during drilling; the parameters of the core set are adjusted by its residual deformation by the calculated value; the well is drilled with a pre-deformed core set. To implement the second case, the paper presents a method for determining the magnitude of the eccentricity of the inertia center of the column set cross-section. In this case, in order to implement the method, it is necessary: to make a rational arrangement of the lower part of the drill string; to carry out the drilling process at the maximum possible rotation frequencies of the drill shaft; to use emulsion washing fluids; to reduce the amount of bending moment due to the operation of diamond crowns that work effectively at low axial forces. Both proposed methods are justified and supported by the results of experimental work. Conclusions. The conducted research allowed us to present and justify a fundamentally new method of reducing the curvature of boreholes based on the use of pre-deformed core sets, as well as to obtain a dependence for determining the optimal value of their residual initial bending, which guarantees a deflection force close to zero on a rock-breaking tool. The magnitude of the eccentricity of the stabilizing arrangement, which guarantees the operation of the guide section in the mode of direct precession: is directly proportional to the force of its interaction with the walls of the well; is inversely proportional to its mass and rotational speed; is directly proportional to the coefficient of sliding friction.

Lateral load resistance of reinforced concrete columns with brittle details

AbstractAnalytical models for shear strength and deformation capacity estimation of reinforced concrete members are essential for the practical implementation of performance‐based seismic evaluation of existing structures and form a key part of current seismic assessment codes (e.g., EN 1998‐3 (2005), (2022), ASCE/SEI 41‐17). Although these models have been derived from regression or calibration of large datasets collected from experimental literature, discrepancy persists between experimental and analytical estimates, especially in cases of members with old‐type detailing. The evident uncertainty about parametric dependencies of the underlying mechanistic problem motivated the present work, where a set of benchmark columns that represent older structural detailing are studied parametrically through advanced finite element simulation. Parameters considered were, the axial load ratio, transverse reinforcement amount and spacing, longitudinal reinforcement ratio, and anchorage/lap splice detailing; results were gauged in terms of the resulting drift ratio (deformation capacity) at the performance limit states and were compared with the Code estimates to evaluate their limits and conservatism. The simulation results were used to vet the assumptions that underlie the simple mechanistic models used in deriving seismic design expressions for yield and ultimate deformation capacities, shear strength, and the rate of its degradation with increasing ductility.

An UPLC-MS/MS method for quantification of spiraeoside in mouse blood and its application to a pharmacokinetic and bioavailability study

AbstractA simple, rapid, and sensitive method based on UPLC-MS/MS was developed to determine spiraeoside in mouse blood, and was applied to the pharmacokinetics and bioavailability of spiraeoside after mice after intravenous (a dose of 5 mg kg−1) and oral (a dose of 20 mg kg−1) administration. On HSS T3 column set at 40 °C, chromatographic separation was obtained with the mobile phase of acetonitrile and 0.1% formic acid using the gradient elution. Spiraeoside and internal standard (IS) were quantitatively analyzed using multiple reaction monitoring (MRM) mode in electrospray (ESI) positive interface. The MRM mode was monitoring the fragmentation of m/z 465.4→303.1 and m/z 451.3→ 289.2 for spironoside and IS, respectively. The results showed a good linear relationship was in the concentration range of 1–200 ng mL−1 (r > 0.998) and the lower limit of quantification (LLOQ) was 1.0 ng mL−1. The intra- and the inter-day precision (RSD%) of the method was within 14.0%, and the accuracy ranged from 90.0% to 115.0%. The extraction recovery of spriaeoside was better than 63.0%, and the matrix effects were in the range of 86%–98%. It also showed the half-life was short, and the absolute bioavailability was 4.0% in mice. Therefore, the established UPLC-MS/MS method was suitable for the pharmacokinetic and bioavailability study of spiraeoside in mice.

Simplified evaluation of the ultimate strength of RC circular members subjected to axial force, bending moment and shear force

The paper proposes a simple analytical tool for the evaluation of the shear strength of reinforced concrete circular, solid or hollow, slender columns endowed with shear reinforcement and subjected to axial force, bending moment and shear force. The proposed method considers the sole beam action by means of simplified stress fields and simultaneously satisfies the equilibrium under the above combined internal forces. The paper identifies basic points in the N-M-V ultimate interaction curve and describes the procedures for the evaluation of the internal forces of these points as well as the procedures for the evaluation of the internal forces of the points in between. The method is first applied to a set of circular solid columns with different geometric and mechanical properties and a comparison is drawn between the shear resistance resulting from the simplified method and that from a more complex non-linear mathematical programming problem proposed in the past by one of the authors. Then, to demonstrate the value of the method and define the field of its accurate application, the proposed method is applied to circular (solid or hollow) columns tested in laboratory by other researchers. Finally, the results of the proposed method are compared with those of some code formulations.

Experimental Study on Ultimate Strength of Steel Tube Column Filled with Reactive Powder Concrete

Composite concrete Filled Tubular Steel (CFT) members, which have excellent deformability due to the well-known confined and constrained interaction between steel tube and concrete, have largely been utilized as bridge piers or columns in high-rise buildings, resulting in increased strength and decreased column size. This study examined the experimental performance of steel tube columns filled with reactive powder concrete (RPC) under axial compression. Three sets of columns were used in the experiment, each with variations in shape (square, rectangular, and circular), length-to-diameter ratio, and compressive strength of the RPC. The first set consisted of five columns, while the second and third sets each had seven columns with three different lengths (750 mm, 600 mm, and 450 mm) and two different compressive strengths (54 and 92 MPa). A new numerical model was developed to calculate the ultimate failure load of the columns by considering factors such as the yield strength of steel, the compressive strength of concrete, the column shape, and the ratio of concrete to steel. This model was validated by comparing the results obtained from the experiments to those predicted by the model, as well as by designing equations from various codes. The results showed that the proposed numerical model accurately predicted the ultimate failure load for columns filled with different types of concrete, especially for RPC, while maintaining conservatism compared to the ACI, AISC, and EN codes equations. Doi: 10.28991/CEJ-2023-09-06-04 Full Text: PDF

Microbial Enhancement of Selenium Removal in Chemically Modified Zeolite Columns

Selenium (Se) is an essential micro-nutrient for living organisms, but elevated concentrations in water can adversely affect health. In this research, we investigate the removal of selenium oxyanions (selenate and selenite) in aqueous systems by integration of adsorption on modified zeolites and microbial reduction. Dynamic sorption-reduction experiments were conducted using two sets of zeolite columns for the removal of selenite and selenate oxyanions, respectively. In each case, one column was fully packed with natural, unmodified zeolites, while the other column was composed of 80% natural and 20% iron-coated zeolites, by mass. The initial selenium concentration, selenite (SeIV) or selenate (SeVI), was 790 μg/L, the pH was 7.5, and the flow rate was 3 mL/min. Initially, as expected, the higher selenate removal (34%) was observed with coated zeolite, twice as high compared to the results with unmodified zeolite. Maximum selenite removal was 89% in the column with modified zeolite. Within approximately 14 days, as the biofilm developed inside the columns, selenium reduction in all four columns reached approximately 99%. Biofilm microbial community composition, assessed by 16S rRNA sequencing, is consistent with the presence of mainly selenium-reducing bacteria (Veillonella, Bacteroides, and Escherichia). Selenium oxyanions were reduced to elemental selenium, visible within the bioreactors as red-color aggregates.

Numerical investigation of thermo-fluid behaviour in a channel with PCM-filled columns

Microalgae has been identified as a potential source in the production of biofuel. Photobioreactors, which are used for microalgae production, normally experience temperature variations over the diurnal cycle due to changes in ambient conditions. Such temperature variations affect microalgae growth since microalgae are sensitive to these temperature variations. Hence, the thermal regulation of photobioreactors to minimize temperature variations will result in higher yield of microalgae. The present research is aimed to investigate a novel approach to thermally regulate photobioreactors using phase change materials (PCM) where the latent heat of the material is exploited as the energy storage mechanism. The present research uses a numerical approach to study the flow and thermal behaviors in a channel with a set of thermal energy storage columns placed at some offset from each other. The research aims to investigate the transient thermal response of the channel flow in the presence of these columns. Open source CFD software, OpenFOAM, is used to numerically simulate flow in a rectangular channel containing offset PCM columns. A parametric analysis to investigate the impact of various operating and geometric properties on the heat transfer to the PCM columns showed that geometric parameters such as the gap and blockage ratios, column aspect ratio, column shape and column arrangement in the channel influence thermal energy storage in PCM-filled columns.

Particle Swarm Optimized Compact, Low Loss 3-dB Power Splitter Enabled by Silicon Columns in Silicon-on-Insulator

We demonstrate a 3-dB power splitter optimized by an enhanced particle swarm optimization algorithm based on a curved directional coupler, with a set of silicon columns introduced into the coupling region. The proposed device exhibits compact size, low loss and low wavelength dependence in the O-band. We employ the particle swarm optimization algorithm to engineer the dispersion by designing the radius of the silicon columns automatically. The demonstrated 3-dB power splitter enabled by silicon columns in silicon-on-insulator can achieve multiple performance metrics simultaneously according to our simulation results, with a compact footprint as small as 11.9 µm, low excess loss as low as 0.04 dB and broad 3-dB operational bandwidth of 60 nm with transmission fluctuations within 0.05 in the wavelength range from 1270 to 1330 nm. This work pioneers the silicon columns in the coupling region and adopts an enhanced particle swarm optimization algorithm to optimize device properties, providing significant potential for application in large-scale PICs as well as offering a new degree of freedom in the design of power splitters.

Factors affecting mixed-mode retention properties of cation-exchange stationary phases

Cation-exchange stationary phases were characterized in different chromatographic modes (HILIC, RPLC, IC) and applied to the separation of non-charged hydrophobic and hydrophilic analytes. The set of columns under investigation included both commercially available cation-exchangers and self-prepared PS/DVB-based columns, the latter consisting of adjustable amounts of carboxylic and sulfonic acid functional groups. The influence of cation-exchange site and polymer substrate on the multimodal properties of cation-exchangers was identified using selectivity parameters, polymer imaging and excess adsorption isotherms. Introducing weakly acidic cation-exchange functional groups to the unmodified PS/DVB-substrate effectively reduced hydrophobic interactions, whilst a low degree of sulfonation (0.09 to 0.27% w/w sulphur) mainly influenced electrostatic interactions. Silica substrate was found to be another important factor for inducing hydrophilic interactions. The presented results demonstrate that cation-exchange resins are suitable for mixed-mode applications and offer versatile selectivity.

Score Function for the Optimization of the Performance of Forward Fill/Flush Differential Flow Modulation for Comprehensive Two-Dimensional Gas Chromatography.

Modulation is the key element of the comprehensive 2D gas chromatography separation. Forward fill/flush flow modulation is cost effective, robust and suitable for analysis of a wide range of samples. Even though this modulation system is well known, studies regarding its optimization are sparse. In this work, based on hundreds of experiments involving multiple column sets and modulation conditions, an approach was proposed that permits to facilitate the choice of the forward fill/flush flow modulation parameters. A score function was developed that allows to predict the forward fill/flush flow modulation process efficiency as judged by the modulated peak shape. The score function was based on the physical rules for optimized and quantitative forward fill/flush flow modulation proposed in our previous work, which state that the sum of the fill and flush modulation distances should be close to the modulation channel length and that the ratio of the flush and fill distances should be sufficiently high for efficient channel flushing. The score function was embedded in a freely available tool in the form of a forward fill/flush flow modulation calculator, which allows the user either to quickly check the relevancy of the modulation operating conditions or to obtain a suggestion for optimal modulation parameters.

Near equatorial paleoclimatic evolution and control on organic matter accumulation during the Cenomanian in the Abu Gharadig Basin, southern Tethys: Insights from palynology, organic petrography, and geochemistry

The beginning of the Late Cretaceous (Cenomanian) attested to a major marine transgression interrupted by sea level falls in north Africa, which led to significant environmental perturbation and widespread accumulation of organic matter-rich sediments. During this period, northern Egypt was located at the southern edge of the Tethys Ocean and deposition of thick siliciclastic alternations between shales, siltstones, and sandstones of the Bahariya Formation took place in the BED2 gas field of the Abu Gharadig Basin, north Western Desert. An integrated approach of palynofacies analysis and palynomorph composition, organic petrography, and geochemical analysis of total organic carbon (TOC)/Rock-Eval pyrolysis, carbonate content, XRD analysis, and clay mineralogy of thirty-nine cutting samples obtained from the lower-middle Cenomanian Bahariya Formation was conducted. This approach was used to characterize organic matter and possible occurrence of source rock intervals, paleoenvironmental and paleoclimatic conditions and their role in organic matter accumulation. Moderate to high proportions of pteridophyte and water fern spores and pollen grains of Araucariaceae (Araucariacites), Cheirolepidiaceae (mainly Classopollis), and Gnetalean (Elaterate pollen) and Afropollis versus the sparsely recorded xerophilous ephedroids (Ephedripites) indicate prevalent conditions of a warm and humid climate. This is consistent with clay mineral composition that is dominated mainly by kaolinite and smectite compared to low illite and the lack of chlorite, which indicated a predominantly warm-humid climate state. Palynofacies analysis showed two assemblages; the first one is dominated by phytoclasts and indicates gas-prone Type III kerogen and deposition in a fluvio-deltaic environment. The second palynofacies assemblage is characterized by moderate abundance of phytoclasts and AOM mostly of terrestrial origin, suggesting a mixed Type III/II kerogen and deposition in a marginal to shallow neritic shelf environment. The organic geochemical characterization showed relatively low average values of TOC, S2, and HI, indicating that the Bahariya Formation is characterized by Type III gas-prone kerogen. Thermal maturity of the Bahariya Formation ranges from immature to the early stage of the oil window. Additionally, organic matter characteristics of the Bahariya Formation are qualitatively and quantitatively similar to their equivalents from nearby basins. Low TOC contents are attributed to a high sedimentation rate and an increased terrestrial input of sand- and silt-sized fractions at shallow water column settings that controlled strong dilution and decomposition versus low burial efficiency of the organic matter.

A simple in situ method for optimizing settings for the Einzel lens elements in a focused ion beam.

Ion beams have had an incredible impact on research in the past couple of decades. One major reason for this is the continued development of systems having optimal beam currents that allows one to image more clearly at different spot sizes to include higher currents that allow for faster milling. The advancements for Focused ion beam (FIB) columns have developed rapidly due to the computational optimization of lens designs. However, once a system has been produced, the optimal column settings for these lenses may change or simply become obscure. Our work involves regaining this optimization with the newly applied values through a new algorithm, requiring hours, rather than the days or weeks that existing methods require. FIB columns frequently utilize electrostatic lens elements (normally two, condenser and objective). This work presents a method to quickly determine the optimal lens 1 (L1) values for large beam currents (∼1 nA or greater), from a carefully acquired set of images without any detailed knowledge of the column geometry. Each set of images, acquired through a voltage sweep of the objective lens (L2) for a preset L1, is partitioned for its spectral content. The sharpest position at each spectral level is used to assess how close the preset L1 is to the optimal. This procedure is conducted for a range of L1 values, the optimal being the one having the smallest range in spectral sharpness. For a system that has suitable automation in place, the time to optimize L1 for a given beam energy and aperture diameter is ∼1.5 h or less. In addition to the technique for finding optimal condenser and objective lens parameters, an alternative peak determination method is presented.