Single Column Research Articles

Investigation on the Retention and Separation of Glucosinolates With a Mixed‐Mode Reversed‐Phase/Weak Anion‐Exchange Column

ABSTRACTGlucosinolates, a crucial group of secondary metabolites in Brassica vegetables, present significant chromatographic separation challenges due to their anionic form, structure diversities, and co‐existence of other phenolic compounds. This study comparatively investigated the retention and separation of seven glucosinolates using a mixed‐mode reversed‐phase/weak anion‐exchange column and a conventional reversed‐phase C18 column. Separation factors for each glucosinolate with its adjacent peaks were over 1.0 on the mixed‐mode column, while co‐eluting was observed on the C18 column. The effects of mobile phase additives and pH on the separation and retention of glucosinolates were also investigated. Results showed that glucosinolate retention was inversely related to both buffer concentration and pH. The optimized method for the mix‐mode column was applied to the complex Brassica vegetable samples. In addition to the 17 well‐resolved glucosinolate peaks, 34 peaks for phenolic compounds were identified in broccoli microgreen, suggesting the successful application scenarios for qualitative analysis in comparison with the single mode reverse phase C18 column. This study demonstrates that the mixed‐mode reversed‐phase/weak anion‐exchange column can be used as a promising separation tool for organic anions in a complex sample matrix.

Distillation column optimization: A formal method using stage-to stage computations and distributed streams

This work addresses the complexities of optimizing the number of stages in a distillation column, which typically lead to challenging non-linear mixed-integer optimization problems. To simplify this, we employ distributed streams, thereby eliminating discrete degrees of freedom. To avoid sophisticated initialization procedures, the optimization problem is reformulated by employing a sequence of stage-to-stage calculations, each reduced to maintaining only the MESH (mass, equilibrium, summation, heat) equations for a single stage.Our numerical experiments show the efficiency and stability of solving the simplified optimization problem in various scenarios, including single and multiple distillation columns. For a single column scenario, we compare the accuracy of our optimization method with a full enumeration approach. Additionally, for a pressure swing flowsheet designed to separate an azeotropic mixture, we illustrate potential energy savings by optimizing a stage distribution versus using a predetermined stage distribution.

A 3D Robust and Microporous B←N Framework with 8‐connected Sandwich Nodes for Efficient Separation of Hexane Isomers

Recently B←N organic frameworks (BNFs) have gained substantial attention owing to their unique dative bond energy, which imparts them with specialized functionalities across a broad spectrum of applications. Despite previous reports on BNFs with permanent porosity, research endeavors towards three‐dimensional (3D) BNFs with similar properties are scarce, with no report of robust 3D BNFs featuring permanent porosity to date. Herein, electrostatic complementarystrategy is proposed to construct the first example of 3D robust and microporous BNF, BNF‐100, featuring a reo topology with 8‐connected sandwich nodes assembled via dative B←N bonds. The activated form BNF‐100a exhibits excellent chemical stability and permanent porosity with Langmuir surface area of 645.9 m2 g−1 and pore volume of 0.23 cm3 g−1. BNF‐100a can efficiently separate hexane isomers through sieving mechanisms, as confirmed by vapor adsorption experiments and dynamic breakthrough tests, surpassing the performance of most MOF materials. Finally, we achieved the purification of different branched hexane isomers using a single breakthrough column in a combined breakthrough and purging experiment, which is the first reported instance in the literature on hexane isomer separation.

A 3D Robust and Microporous B←N Framework with 8-connected Sandwich Nodes for Efficient Separation of Hexane Isomers.

Recently B←N organic frameworks (BNFs) have gained substantial attention owing to their unique dative bond energy, which imparts them with specialized functionalities across a broad spectrum of applications. Despite previous reports on BNFs with permanent porosity, research endeavors towards three-dimensional (3D) BNFs with similar properties are scarce, with no report of robust 3D BNFs featuring permanent porosity to date.Herein,electrostatic complementarystrategyisproposedto constructthe first example of3Drobust and microporousBNF,BNF-100, featuring areotopology with 8-connected sandwich nodes assembled via dative B←N bonds. The activated formBNF-100aexhibits excellent chemical stability and permanent porosity with Langmuir surface area of 645.9 m2g-1and pore volume of 0.23 cm3 g-1.BNF-100acan efficiently separate hexane isomers through sieving mechanisms, as confirmed by vapor adsorption experiments and dynamic breakthrough tests, surpassing the performance of most MOF materials.Finally, we achieved the purification of different branched hexane isomers using a single breakthrough column in a combined breakthrough and purging experiment, which is the first reported instance in the literature on hexane isomer separation.

Characterization of adeno-associated virus capsid proteins using denaturing size-exclusion chromatography coupled with mass spectrometry

Recombinant adeno-associated viruses (AAVs) are a highly effective platform for gene delivery for the treatment of many human diseases. Characterization of AAV viral protein attributes (VP), such as serotype identity, VP stoichiometry, and VP post-translational modifications, is essential to ensure product and process consistency. While size-exclusion chromatography (SEC) coupled with mass spectrometry (MS) is commonly used in the biopharmaceutical industry for analyzing protein therapeutics, its application to intact AAV VP components has not gained traction, presumably due to difficulties in achieving adequate resolution of VP(1−3) monomers. Herein, we describe the development of a denaturing SEC method and optimization of SEC parameters, including stationary phase pore size, column temperature, and mobile phase composition, to achieve effective chromatographic separation of VP(1−3). We demonstrate that an optimized dSEC-MS method featuring MS-compatible formic acid, can effectively separate VP(1−3) across AAV1, 2, 5, 6, 8, and 9 serotypes using a single column and mobile phase condition. A case study was included to showcase successful application of the dSEC-MS method in analyzing changes across different AAV production processes, yielding similar conclusions to an orthogonal approach, such as hydrophilic interaction chromatography (HILIC)- MS. Additionally, dSEC integrated with fluorescence (FLR) and ultraviolet (UV) detection can be used to semi-quantitatively identify both AAV DNA and VP components from empty and full AAV samples. Overall, this robust and MS-friendly methodological advancement could greatly streamline the development and analytical quality control processes for AAV-based gene therapies, providing a highly sensitive method for intact VP characterization.

A Streamlined High-Throughput LC-MS Assay for Quantifying Peptide Degradation in Cell Culture.

Peptides are widely used in biomaterials due to their easy of synthesis, ability to signal cells, and modify the properties of biomaterials. A key benefit of using peptides is that they are natural substrates for cell-secreted enzymes, which creates the possibility of utilizing cell-secreted enzymes for tuning cell-material interactions. However, these enzymes can also induce unwanted degradation of bioactive peptides in biomaterials, or in peptide therapies. Liquid chromatography-mass spectrometry (LC-MS) is a widely used, powerful methodology that can separate complex mixtures of molecules and quantify numerous analytes within a single run. There are several challenges in using LC-MS for the multiplexed quantification of cell-induced peptide degradation, including the need for non-degradable internal standards and the identification of optimal sample storage conditions. Another problem is that cell culture media and biological samples typically contain both proteins and lipids that can accumulate on chromatography columns and degrade their performance. However, removing these constituents can be expensive, time consuming, and increases sample variability. Here we show that directly injecting samples onto the LC-MS without any purification enables rapid and accurate quantification of peptide concentration, and that hundreds of LC-MS runs can be done on a single column without a significantly diminish the ability to quantify the degradation of peptide libraries. We also show that column failure is evident when hydrophilic peptides fail to be retained on the column, and this can be easily identified using standard peptide mixtures for column benchmarking. In total, this work introduces a simple and effective method for simultaneously quantifying the degradation of dozens of peptides in cell culture. By providing a streamlined and cost-effective method for the direct quantification of peptide degradation in complex biological samples, this work enables more efficient assessment of peptide stability and functionality, facilitating the development of advanced biomaterials and peptide-based therapies.

Absorption of electromagnetic waves by cylindrical surface plasmon resonance

Abstract The absorption characteristics of cylindrical surface plasmon resonance (CSPR) have been studied. We demonstrated that a single plasma column with CSPRs can achieve high absorptivity at the plasmon frequency. We also studied the effects of plasma density and collision frequency on the absorptivity. As both of them increase, the corresponding absorptivity tends to increase first and then decrease, but with different reasons. Such manifestation is explained by analyzing transmission and reflection spectra in both cases, as well as magnetic field distribution patterns at the frequency of plasmon. On the one hand, the increase in plasma density leads to the enhancement of plasmons, improving transmittance; On the other hand, the increase in collision frequency leads to a weakening of plasmons and an increase in reflectivity. Finally, we investigated the absorption characteristics of plasmons in the plasma photonic crystals (PPCs) structure and overcame the absorption attenuation caused by the increase in plasma density by increasing the number of plasma columns. Meanwhile, the absorption generated by surface plasmon resonance is not affected by the lattice constant of PPCs. The research has shown that efficient absorption can be achieved using CSPR, resulting in extremely high absorptivity when using fewer plasma columns. Finally, we verified the absorption ability of CSPRs through experiments.

Theoretical and experimental investigation of flexible air spring stiffness in a tuned liquid column gas damper for vertical vibration control

This study investigates the effectiveness of equivalent linear air spring stiffness in a Vertical Tuned Liquid Column Gas Damper (VTLCGD) for reducing vertical structural vibrations, particularly considering different sealing conditions. The VTLCGD system, designed with a single sealed vertical air column, allows flexible frequency tuning by adjusting the air spring stiffness. It aims to be used in low-frequency structures where conventional VTLCGD designs with two sealed ends are less efficient. The geometric configuration and working principle of the VTLCGD are first described. The equation of motion is derived using liquid dynamic equilibrium and the pressure-volume relationship, with expressions for natural frequency and control force validated through shaking table tests conducted with varying VTLCGD lengths. Experimental investigations are conducted to examine the parameters affecting damper performance using pressure data. The system's vibration reduction performance is then numerically evaluated on a cantilevered floor subjected to human walking. The numerical results, based on the equation of motion for liquid displacement and natural frequency, show good agreement with experimental data, which confirms the effectiveness of using linearized air spring stiffness for frequency tuning. The effects of total liquid length and height difference on control force are further investigated, and a polytropic index of 1.2 is determined for the VTLCGD frequency formula. The VTLCGD system achieves a maximum vibration reduction of 52.63 % in acceleration response on the cantilevered floor compared to the uncontrolled case. Moreover, the variation in stiffness due to changes in the sealing condition is presented to validate the damper's adaptability over a wide frequency range.

Matching Tabular Data to Knowledge Graph with Effective Core Column Set Discovery.

Matching tabular data to a knowledge graph (KG) is critical for understanding the semantic column types, column relationships, and entities of a table. Existing matching approaches rely heavily on core columns that represent primary subject entities on which other columns in the table depend. However, discovering these core columns before understanding the table’s semantics is challenging. Most prior works use heuristic rules, such as the leftmost column, to discover a single core column, while an insightful discovery of the core column set that accurately captures the dependencies between columns is often overlooked. To address these challenges, we introduce Dependency-aware Core Column Set Discovery ( DaCo ), an iterative method that uses a novel rough matching strategy to identify both inter-column dependencies and the core column set. Additionally, DaCo can be seamlessly integrated with pre-trained language models, as proposed in the optimization module. Unlike other methods, DaCo does not require labeled data or contextual information, making it suitable for real-world scenarios. In addition, it can identify multiple core columns within a table, which is common in real-world tables. We conduct experiments on six datasets, including five datasets with single core columns and one dataset with multiple core columns. Our experimental results show that DaCo outperforms existing core column set detection methods, further improving the effectiveness of table understanding tasks.

Experimental and theoretical study on axial compression behaviour of the modular combined column

Between the modular units of the modular steel building, there exists a combination of the adjacent modular columns. Due to the gaps between the modular columns and the lack of horizontal connections, the integrity of the modular steel structure is weak, which limits the use of modular steel structures in high-rise buildings. This paper proposes a kind of modular combined column realized the connection of modular single columns through the connectors and concrete, which can improve the integrity of the modular steel building. The assembly process of this new modular combined column is described. For axial compressive performance tests, four modular combined column specimens were designed, each with different height or different number of connecting plates. The axial compressive bearing capacity, ductility, stiffness, and other mechanical parameters of the specimens were analyzed according to the phenomena and load-displacement curves of the test. Then, the axial compression failure mode of the modular combined column specimens is compared and analyzed in conjunction with the finite element model. The results indicate that the axial compressive performance and ductility of the combined column suggested in this research are exceptional. The connector can enhance the overall mechanical qualities of the combined column by augmenting the restraining impact of concrete. Finally, the theoretical equation of the axial compression bearing capacity of the modular combined column is obtained by employing the superposition principle, and the equation's reliability is confirmed, along with the test results and the results of the numerical analysis.

A new strategy to design the purification process of ethyl tertiary butyl ether gasoline additive via hybrid extractive-reactive distillation

Here we propose a new strategy for designing the purification process of ethyl tertiary butyl ether (ETBE) gasoline additive. Our proposal suggests replacing the last two columns of the triple-column extractive distillation process from previous work with a single reactive distillation column. This column incorporates an ethylene oxide hydration reaction, yielding ethylene glycol, which can be utilized as a solvent for extractive distillation. This replacement is able to reduce the total number of columns, the amount of solvent needed, and significantly decreases total energy consumption up to 32% compared to the original process. Furthermore, it benefits from the redistribution of energy between different steam-grade utilities, enabling significant reduction in operational costs. These advantages result in a 3−22% cost decrease compared to the original process. Overall, the proposed process exhibits significant improvements in energy efficiency and cost reduction with respect to the original process with and without heat integration from previous research.

Improving Equatorial Upper Ocean Vertical Mixing in the NOAA/GFDL OM4 Model

AbstractDeficiencies in upper ocean vertical mixing parameterizations contribute to tropical upper ocean biases in global coupled general circulation models, affecting their simulated ocean heat uptake and ENSO variability. To better understand these deficiencies, we develop a suite of ocean model experiments including both idealized single column models and realistic global simulations. The vertical mixing parameterizations are first evaluated using large eddy simulations as a baseline to assess uncertainties and evaluate their implied turbulent mixing. Global models are then developed following NOAA/GFDL's 0.25° nominal horizontal grid spacing OM4 (uncoupled) configuration of the MOM6 ocean model, with various modifications that target biases in the original model. We test several enhancements to the existing mixing schemes and evaluate them against observational constraints from Tropical Atmosphere Ocean moorings and Argo floats. In particular, we find that we can improve the diurnal variability of mixing in OM4 via modifications to its surface boundary layer mixing scheme, and can improve the net mixing in the upper thermocline by reducing the background vertical viscosity, allowing for more realistic, less diffuse currents. The improved OM4 model better represents the mixing, leading to improved diurnal deep‐cycle variability, a more realistic time‐mean tropical thermocline structure, and a better Pacific Equatorial Undercurrent.

Dependence of Contextual Modulation in Macaque V1 on Interlaminar Signal Flow.

In visual cortex, neural correlates of subjective perception can be generated by modulation of activity from beyond the classical receptive field (CRF). In macaque V1, activity generated by nonclassical receptive field (nCRF) stimulation involves different intracortical circuitry than activity generated by CRF stimulation, suggesting that interactions between neurons across V1 layers differ under CRF and nCRF stimulus conditions. Using Neuropixels probes, we measured border ownership modulation within large, local populations of V1 neurons. We found that neurons in single columns preferred the same side of objects located outside of the CRF. In addition, we found that cross-correlations between pairs of neurons situated across feedback/horizontal and input layers differed between CRF and nCRF stimulation. Furthermore, independent of the comparison with CRF stimulation, we observed that the magnitude of border ownership modulation increased with the proportion of information flow from feedback/horizontal layers to input layers. These results demonstrate that the flow of signals between layers covaries with the degree to which neurons integrate information from beyond the CRF.

An 11-bit low power column-parallel single slope ADC with comparator toggle prediction technique for CMOS image sensor

This paper proposes an 11-bit low power column-parallel SS ADC with DCDS for CMOS image sensors. The proposed SS ADC reduces the power consumption in three ways. Firstly, using a combination of coarse and fine quantization can reduce power consumption of counter. Secondly, changing the operation state can remove the bit width inverter. Thirdly, the comparator power is reduced by making each column of comparators switch off after the end of the comparison function. The proposed ADC is fabricated in a 110 nm 1P4M CMOS technology and has a DNL of +0.64/−0.54 LSB and an INL of +0.04/−6.7 LSB at a sampling frequency of 29.9 kS/s. The single column SS ADC has the power consumption ranging from 39.6 μW to 74.87 μW. Compared with the conventional SS ADC, the minimum and the maximum reduction of the power consumption are 20.1 % and 43.8 %, respectively. The average power saving is 34.5 %.

Comparison of orientation encoding across layers within single columns of primate V1 revealed by high-density recordings.

Primary visual cortex (V1) has been the focus of extensive neurophysiological investigations, with its laminar organization serving as a crucial model for understanding the functional logic of neocortical microcircuits. Utilizing newly developed high-density, Neuropixels probes, we measured visual responses from large populations of simultaneously recorded neurons distributed across layers of macaque V1. Within single recordings, myriad differences in the functional properties of neuronal subpopulations could be observed. Notably, while standard measurements of orientation selectivity showed only minor differences between laminar compartments, decoding stimulus orientation from layer 4C responses outperformed both superficial and deep layers within the same cortical column. The superior orientation discrimination within layer 4C was associated with greater response reliability of individual neurons rather than lower correlated activity within neuronal populations. Our results underscore the efficacy of high-density electrophysiology in revealing the functional organization and network properties of neocortical microcircuits within single experiments.

Efficacy of IS Code Provisions for Design of Eccentrically Loaded Single Angle Compression Members

In practical applications, steel single angles are often subjected to eccentric loading when connected to a gusset plate through one leg only, resulting in complex compression behaviour. This behaviour has not been as extensively studied as that of concentrically loaded members. Various international codes of practice offer differed approaches for designing these elements. The literature indicates that the Indian Standard Code IS 800–2007 accurately predicts the axial capacity of eccentrically loaded single angle columns. However, a recent amendment to IS 800 in 2024 introduced modified design provisions. This study is the first to explore the implications of these latest design provisions by comparing them with earlier provisions and experimental strengths reported in the literature. Initially, the design strengths as per the previous and latest design provisions for various Indian Standard Angles (ISA) were presented and compared accounting for varying slenderness ratio, plate slenderness ratio (b/t), and different types of end connections and restraints. The findings reveal that the latest design provisions generally result in much higher design strengths compared to the earlier provisions, with a maximum increase of 104.84%. Upon noticing the significant variation, this study is further extended to compare with the reported data available in the literature. The nominal strengths calculated using the latest provisions were often higher than the strengths reported in the literature considered in this study, indicating potential unsafe design.

Numerical modelling and simulation of methane enrichment: a systematic review on pressure swing adsorption technology

ABSTRACT Enriching methane from sources such as natural gas, biogas, and coalbed methane is a valuable gas separation endeavor, given methane as a cleaner and more sustainable fuel resource. Pressure swing adsorption (PSA) is widely regarded as a mature technology for this purpose. The essence of the mathematical model is to capture the fundamental aspects of the problem, enabling an accurate description of the system. This review summarizes recent trends in the mathematical modelling of PSA for methane enrichment. It provides a comprehensive compilation of numerical modelling and simulation studies, with a critical emphasis on methane enrichment applications. A rigorous mathematical model describing the adsorption phenomenology in a packed bed column is presented, incorporating mass, momentum, and energy balances, which serve as the fundamental framework for the cyclic adsorption process. Key analyses and performance metrics of PSA systems are detailed through examples from the literature. A case study based on a single column is presented to exemplify the mathematical modelling pathway and serve as a basis for model validation. The paper concludes by highlighting instructive avenues for future research directions and development in this area.

Polyvinyl chloride nanoplastics transport inhibited in natural sandy soil by iron-modified biochar.

The small particle size of nanoplastics allows them to migrate through soil and make them highly bioavailable, posing a potential threat to groundwater. Measures are urgently needed to reduce the migration of nanoplastics in soil. However, there is limited research available on this topic. In this study, two types of iron-modified biochar (magnetic corncob biochar (MCCBC) and magnetic walnut shell biochar (MWSBC)) were selected and their effects on the transport of polyvinyl chloride nanoplastics (PVC-NPs) in natural sandy soil columns under different ionic types and strengths were investigated. The results show that the transport of PVC-NPs in single sandy soil columns was rapid and efficient, with the estimated breakthrough rate of 85.10%. However, the presence of MCCBC and MWSBC (0.5%, w/w) significantly inhibited the transport of PVC-NPs in sandy soil columns (p < 0.05), and MCCBC had a stronger inhibitory effect on the transport of PVC-NPs than MWSBC. This can be attributed to the fact that the adsorption of PVC-NPs on adsorbents followed the order as: MCCBC > MWSBC > sandy soil. The retention of PVC-NPs by MCCBC and MWSBC is determined by ionic type and ionic strength. The presence of coexisting ions enhanced the inhibitory effect of iron-modified biochar on the transport of PVC-NPs, with the following order: Ca2+ > SO2- 4 > Cl- > NO- 3. The inhibitory effect of MCCBC and MWSBC on the transport of PVC-NPs in soil columns increased with increasing ionic strengths. Furthermore, MCCBC and MWSBC inhibited the migration of PVC-NPs in a rainwater-soil system. The mechanisms by which MCCBC and MWSBC affect the transport of PVC-NPs in soil columns were considered to enhancing adsorption and decreasing soil pore volume. The results provide new insights into the management of soil nanoplastic pollution.

Dual column chromatography combined with high-resolution mass spectrometry improves coverage of non-targeted analysis of plant root exudates

BackgroundWithin the plant kingdom, there is an exceptional amount of chemical diversity that has yet to be annotated. It is for this reason that non-targeted analysis is of interest for those working in novel natural products. To increase the number and diversity of compounds observable in root exudate extracts, several workflows which differ at three key stages were compared: 1) sample extraction, 2) chromatography, and 3) data preprocessing. ResultsPlants were grown in Hoagland's solution for two weeks, and exudates were initially extracted with water, followed by a 24-h regeneration period with subsequent extraction using methanol. Utilizing the second extraction showed improved results with less ion suppression and reduced retention time shifting compared to the first extraction. A single column method, utilizing a pentafluorophenyl column, paired with high-resolution mass spectrometry ionized and correctly identified 34 mock root exudate compounds, while the dual column method, incorporating a pentafluorophenyl column and a porous graphitic carbon column, retained and identified 43 compounds. In a pooled quality control sample of exudate extracts, the single column method detected 1,444 compounds. While the dual method detected fewer compounds overall (1,050), it revealed a larger number of small polar compounds. Three preprocessing methods (targeted, proprietary, and open source) successfully identified 43, 31, and 38 mock root exudate compounds to confidence level 1, respectively. SignificanceEnhancing signal strength and analytical method stability involves removing the high ionic strength nutrient solution before sampling root exudate extracts. Despite signal intensity loss, a dual column method enhances compound coverage, particularly for small polar metabolites. Open-source software proves a viable alternative for non-targeted analysis, even surpassing proprietary software in peak picking.

Experimental study on seismic performance of a new precast segmental assembled single column bridge pier

Prefabricated bridge technology has come into wide spread use as fabricated technology has advanced, but engineering applications of fabricated bridge technology are primarily focused on the bridge superstructure, considerably restricting the use of prefabricated bridge technology for the bridge substructure due to the uncertainty in the seismic performance and damage mechanism of segmental assembled piers. Based on this, two new segment connection methods were proposed and applied to the prefabricated piers. Four specimens with a scale of 0.4 were designed and manufactured. The seismic performance of two new types of assembled single column piers, namely cone sleeve-FRC (CSF) wet joint segmental assembled pier and main reinforcement lap-UHPC (MRLU) wet joint segmental assembled pier, is investigated and compared with integral cast-in-place pier to analyze the effects of FRC and UHPC on the seismic performance of the piers, using the proposed static test. The results show that the pier connected by cone sleeve-FRC wet joint exhibits a good energy dissipation and ductility, small deformation, the highest peak bearing capacity and the best seismic performance. Based on the tests, finite element models of the members were created, and the member CSF-1, which has the best seismic performance, was parametrically analyzed by taking three influencing factors into account: axial compression ratio, longitudinal reinforcement area and hoop reinforcement spacing. It is indicated that a significant improvement in seismic performance can be achieved by reducing the hoop spacing, increasing the longitudinal reinforcement diameter and axial compression ratio.