Fiber Column Research Articles

Analysis of sediment re-formation factors after ginseng beverage clarification based on XGBoost machine learning algorithm

The aim of this study was to explore the sediment re-formation factors of ginseng beverages subjected to four clarification ways (11 subgroups) including the ethanol precipitation, enzymatic treatment, clarifier clarification, and Hollow Fiber Column (HFC) methods, based on the Extreme Gradient Boosting (XGBoost) model. The results showed that the clarity of the ginseng beverages was significantly improved by all the clarification treatments, but still formed sediment after storage. HFC method exhibited the highest transmittance, the least sediment, and stronger antioxidant activity in the clarification treatment groups. According to the results of chemical composition analyses and partition coefficients, carbohydrates, saponins, proteins and metal elements were involved in varying degrees in the re-formation of the sediments in ginseng beverage after clarification. Based on the above data, the XGBoost model predicted that protein, Rd, Na, K, and total saponins were the five most important chemical components affecting the sediment re-formation in ginseng beverages.

Isolation and quantification of human urinary exosomes using a Tween-20 elution solvent from polyester, capillary-channeled polymer fiber columns

BackgroundExosomes, a subset of extracellular vesicles (EVs), are a type of membrane-secreted vesicle essential for intercellular communication. There is a great deal of interest in developing methods to isolate and quantify exosomes to study their role in intercellular processes and as potential therapeutic delivery systems. Polyester, capillary-channeled polymer fiber columns and spin-down tips are highly efficient, low-cost means of exosome isolation. As the methodology evolves, there remain questions as to the optimum elution solvent for specific end-uses of the recovered vesicles; fundamental biochemistry, clinical diagnostics, or therapeutic vectors. ResultsWhile both acetonitrile and glycerol have been proven highly successful in terms of EV recoveries in the hydrophobic interaction chromatography workflow, many biological studies entail the use of the non-ionic detergent, Tween-20, as a working solvent. Here we evaluate the use of Tween-20 as the elution solvent for the recovery of exosomes. A novel 10-min, two-step gradient elution method, employing 0.1 % v/v Tween-20, efficiently isolated EVs at a concentration of ∼1011 EV mL−1 from a 100 μL urine injection. Integration of absorbance and multi-angle light scattering detectors in standard HPLC instrumentation enables a comprehensive single-injection determination of eluted exosome concentration and sizes. Transmission electron microscopy verifies the retention of the vesicular structure of the exosomes. The micro-bicinchoninic acid protein quantification assay confirmed high-purity isolations of exosomes (∼99 % removal of background proteins) SignificanceThe effective use of Tween-20 as an elution solvent for exosome isolation/purification using capillary-channeled polymer fiber columns adds greater versatility to the portfolio of the approach. The proposed method holds promise for a wide range of fundamental biochemistry, clinical diagnostics, and therapeutic applications, marking a significant advancement in EV-based methodologies.

The Effect of Polymyxin B-Immobilized Fiber Column Hemoperfusion for Sepsis: A Systemic Review and Meta-Analysis

Purpose: The objective of this study was to evaluate the effect of Polymyxin B hemoperfusion (PMX-HP) on patients with sepsis.Methods: A systematic review and meta-analysis was performed using relevant articles retrieved from 3 databases (PubMed, Cochrane Library, EMBASE). Randomized studies from 1 January 1999 to 28 February 2022 were examined to determine the clinical results of PMX-HP. A meta-analysis was carried out using the random-effects method, meta-regression with clinical variables, and assessment of risk of bias (ROB) tool (Cochrane ROB assessment tool). Mortality was evaluated within 60 days of hospitalization (in-hospital death 28-day, 30-day, and 60-day mortality) and predictors associated with mortality were determined using meta-regression.Results: There were 11 randomized studies with 548 patients included in the meta-analysis. The pooled mortality was 35% (95% CI, 27%-42%, 95% CI 0.53-0.96). Further subgroup analysis was performed according to the duration of PMX-HP. An extension of PMX-HP treatment beyond 2 hours (pooled mortality, 43%; 95% CI, 9%-76%) compared with a 2-hour session (pooled mortality, 33%. 95% CI, 27%-38%) showed an increase in mortality rates. However, this was not statistically significant. Univariate meta-regression showed that patient’s age, the acute physiology and chronic health evaluation score, and the sequential organ failure assessment score did not significantly impact mortality.Conclusion: While PMX-HP is valuable in the management of septic shock, treatment duration should be based on careful assessment of the patient's condition, the risks and benefits of prolonged therapy, and the overall treatment strategy including antimicrobial management and source control.

Blood perfusion with polymyxin B immobilized columns in patients with COVID-19 requiring oxygen therapy

Extracorporeal blood purification with polymyxin B immobilized fiber column direct hemoperfusion (PMX-DHP), is reported to be effective in treating COVID-19 pneumonitis with oxygen demand. This multicenter prospective study evaluated the efficacy and safety of PMX-DHP in oxygen-requiring patients with COVID-19 admitted between September 28, 2020, and March 31, 2022. The primary endpoint was the percentage of clinical improvement 15 days after treatment. The secondary endpoint was the percentage of worsened disease status. Data from the COVID-19 patient registry were used for the synthetic control group. The improvement rate on Day 15 did not differ between PMX-treated patients and controls; however, the deterioration rate was 0.38 times lower in the PMX-treated group, and the death rates on Day 29 were 0 and 11.1% in the PMX-treated and control groups, respectively. The PMX group showed a 0.73 times higher likelihood for reduced intensive care demand, as 16.7% of PMX-treated patients and 22.8% of controls worsened. After treatment blood oxygenation improved, urinary β2-microglobulin and liver-type fatty acid-binding protein showed significant decreases, and IL-6 decreased once during treatment but did not persist. In this study, PMX treatment effectively prevented the worsening of COVID-19 pathology, accompanied by improved oxygenation. PMX treatment to remove activated cells may effectively improve patient outcomes.

Cost-effective moisture-induced electrical power generators for sustainable electrodialysis desalination

To establish a sustainable method for desalination, it is necessary to explore and use renewable energy sources that are cost-effective and unaffected by weather conditions. Therefore, in this study we propose a novel hybrid electrodialysis system for environmentally friendly and cost-effective desalination of blackish water, integrating moisture-induced electrical power generators (MIEPGs). By coating a layer of carbon black on the surface of cellulose acetate fiber columns, which are readily available as cigarette filters, compact MIEPGs can be conveniently fabricated. These MIEPGs can generate electricity from trace amounts of moisture by leveraging the streaming potential induced along nanoscale channels between the carbon black particles. A notable voltage output (13.5–22 V) is achieved from the series connection of 90 cells using a customized module frame. The substantial power output derived from the stacked MIEPGs enables the successful desalination of modeled brackish water with a salt removal ratio of 92%.

Continuous catalytic production of 1,3-dihydroxyacetone: Sustainable approach combining perfusion cultures and immobilized cells

Currently, the predominant method for the industrial production of 1,3-dihydroxyacetone (DHA) from glycerol involves fed-batch fermentation. However, previous research has revealed that in the biocatalytic synthesis of DHA from glycerol, when the DHA concentration exceeded 50 g·L−1, it significantly inhibited microbial growth and metabolism, posing a challenge in maintaining prolonged and efficient catalytic production of DHA. In this study, a new integrated continuous production and synchronous separation (ICSS) system was constructed using hollow fiber columns and perfusion culture technology. Additionally, a cell reactivation technique was implemented to extend the biocatalytic ability of cells. Compared with fed-batch fermentation, the ICSS system operated for 360 h, yielding a total DHA of 1237.8 ± 15.8 g. The glycerol conversion rate reached 97.7 %, with a productivity of 3.44 g·L−1·h−1, representing 485.0 % increase in DHA production. ICSS system exhibited strong operational characteristics and excellent performance, indicating significant potential for applications in industrial bioprocesses.

In-line coupling of capillary-channeled polymer fiber columns with optical absorbance and multi-angle light scattering detection for the isolation and characterization of exosomes

Extracellular vesicles (EVs) have garnered much interest due to their fundamental role in intracellular communication and their potential utility in clinical diagnostics and as biotherapeutic vectors. Of particular relevance is the subset of EVs referred to as exosomes, ranging in size from 30 to 150 nm, which contain incredible amounts of information about their cell of origin, which can be used to track the progress of disease. As a complementary action, exosomes can be engineered with therapeutic cargo to selectively target diseases. At present, the lack of highly efficient methods of isolation/purification of exosomes from diverse biofluids, plants, and cell cultures is a major bottleneck in the fundamental biochemistry, clinical analysis, and therapeutic applications. Equally impactful, the lack of effective in-line means of detection/characterization of isolate populations, including concentration and sizing, is limiting in the applications. The method presented here couples hydrophobic interaction chromatography (HIC) performed on polyester capillary-channeled polymer (C-CP) fiber columns followed by in-line optical absorbance and multi-angle light scattering (MALS) detection for the isolation and characterization of EVs, in this case present in the supernatant of Chinese hamster ovary (CHO) cell cultures. Excellent correlation was observed between the determined particle concentrations for the two detection methods. C-CP fiber columns provide a low-cost platform (< $5 per column) for the isolation of exosomes in a 15-min workflow, with complementary absorbance and MALS detection providing very high-quality particle concentration and sizing information.

Effects of Early Initiation of Polymyxin B Hemoperfusion Therapy in Patients with Cancer with Refractory Septic Shock.

Background: We aimed to analyze the correlation between in-hospital mortality and hemodynamic changes, using polymyxin B-immobilized fiber column direct hemoperfusion (PMX-DHP) initiation time in patients with cancer with refractory septic shock. Methods: Forty-six patients with cancer who received PMX-DHP for refractory septic shock were retrospectively analyzed and classified into early (≤3 h between refractory septic shock and PMX-DHP; n = 17) and late (>3 h; n = 29) initiation groups. The vasopressor inotropic score (VIS), sequential organ failure assessment (SOFA) score, and lactate clearance before and 24 h post-PMX-DHP were compared. Results: Overall, 52.17% died from multiple organ dysfunction, with a lower mortality rate in the early initiation group. The VIS and SOFA score decreased in both groups, but the magnitude of decrease was not significant. Lactate clearance improved in both groups, with greater improvement in the early initiation group. Univariable analysis identified associations of in-hospital mortality with early initiation, ΔC-reactive protein, lactate clearance, ΔSOFA score, and ΔVIS. Multivariable analysis demonstrated associations of in-hospital mortality risk with ΔSOFA score and early PMX-DHP initiation. Overall survival was higher in the early initiation group. Early initiation of PMX-DHP in patients with cancer with refractory septic shock reduced in-hospital mortality and improved lactate clearance.

Arsenic removal adsorbent using limonite-polyethersulfone composite fiber via continuous flow column process.

This research introduces an enhanced limonite-based composite fiber adsorbent for arsenic (As) removal. The modification involves creating polyethersulfone (PES)-limonite composite fibers loaded with 60 wt% limonite powders, designed to be applicable in water flow environments. The fibers were prepared using a wet-spinning process based on phase inversion, with varying concentrations (10, 20, and 30 wt%) of PES in NMP solution. The composite fiber with 10wt% NMP exhibited a porous structure and demonstrated efficient absorption of both As(III) and As(V). Adsorption followed the Langmuir model, with qm values of 1.5mg/g for As(III) and 3.2mg/g for As(V) at pH6. In column experiments, As removal rates increased with contact time, attributed to decreased flow rates (1mL/min). Moreover, increasing fiber column height led to enhanced removal rates, as indicated by the Adams-Bohart model. The mechanism for As(V) removal involved the formation of an inner-sphere complex through ion exchange between α-FeOOH and HAsO4 - and H2 AsO4 2- in an aqueous solution at pH6.8. PRACTITIONER POINTS: Changing the polyethersulfone ratio in the composite leads to variations in the appearance of limonite within each composite fiber. Limonite composite fibers effectively remove As(III) and As(V) at neutral pH. The adsorption behavior follows Langmuir kinetic model, the qm of 1.5mg/g for As(III) and 3.2mg/g for As(V). Longer columns and contact times enhance arsenic (As) removal in practical water treatment systems. Adam-Bohart model aids in predicting breakthrough and saturation time in As adsorption column design.

Aggressive multi-combination therapy for anti-MDA5 antibody-positive dermatomyositis-rapidly progressive interstitial lung disease.

To elucidate the efficacy and safety of aggressive multi-combination therapy with mycophenolate mofetil, rituximab, and plasma exchange or polymyxin B immobilized fiber column direct hemoperfusion followed by conventional therapy with corticosteroids, calcineurin inhibitors, and intravenous pulse cyclophosphamide in patients with rapidly progressive interstitial lung disease (RPILD) with anti-melanoma differentiation-associated gene 5 (MDA5)-antibody-positive dermatomyositis (DM). A total of 23 patients with anti-MDA5 antibody-positive DM-RPILD were enrolled, with nine patients in Group A (treated conventionally before March 2015) and 14 patients in Group B (received aggressive treatment after April 2015). Pretreatment severity of interstitial lung disease (ILD) did not differ between the two groups. However, Group B exhibited a higher cumulative survival rate at 48 weeks than Group A (64.3% vs. 33.3%). The corticosteroid dose, divided by the initial dose at 3 months and 12 months, was significantly lower in Group B than in Group A (p = .046 and .026, respectively). Among the ILD-related deaths in Group B, there was a tendency toward a higher proportion of males and more severe ILD. The incidence of infection did not differ between the groups, but leukopenia was more common in Group B. This aggressive multi-combination therapy may improve the survival outcome of patients with anti-MDA5 antibody-positive DM-RPILD. However, careful management of complications, such as opportunistic infections and leukopenia, is essential. Future refinement through longitudinal investigations tracking the long-term efficacy, safety, and cost-effectiveness of this treatment strategy is needed.

A successful application of adult polymyxin B-immobilized fiber column hemoperfusion to a neonate with septic shock.

A successful application of adult polymyxin B-immobilized fiber column hemoperfusion to a neonate with septic shock.

Endotoxin removal therapy with Polymyxin B immobilized fiber column: a single center experience from EUPHAS2 registry

Although the precise clinical indication for initiation of PMX-HA is widely debated in the literature, a proper patient selection and timing of treatment delivery might play a critical role in the clinical course of a specific subphenotype of septic shock (endotoxic shock). In light of this view, since 2019, we have introduced in our clinical practice a diagnostic-therapeutic flowchart to select patients that can benefit the most from the treatment proposed. In addition, we reported in this study our experience of PMX-HA in a cohort of critically ill patients admitted to our intensive care unit (ICU). We analyzed a single centre, retrospective, observational web-based database (extracted from the EUPHAS2 registry) of critically ill patients admitted to the ICU between January 2016 and May 2021 who were affected by endotoxic shock. Patients were divided according to the diagnostic-therapeutic flowchart in two groups: Pre-Flowchart (Pre-F) and Post-Flowchart (Post-F). From January 2016 to May 2021, 61 patients were treated with PMX-HA out of 531 patients diagnosed with septic shock and of these, fifty patients (82%) developed AKI during their ICU stay. The most common source of infection was secondary peritonitis (36%), followed by community-acquired pneumonia (29%). Fifty-five (90%) out of 61 patients received a second PMX-HA treatment, with a statistically significant difference between the two groups (78% of the Pre-F vs. 100% of the Post-F group, p = 0.005). In both groups, between T0 and T120, the Endotoxin Activity Assay (EAA) decreased, while the SOFA score, mean arterial pressure (MAP), and Vasoactive Inotropic Score (VIS) improved with no statistically significant difference. Furthermore, when performing a propensity score matching analysis to compare mortality between the two groups, statistically significant lower ICU and 90-day mortalities were observed in the Post-F group [p = 0.016]. Although in this experienced centre data registry, PMX-HA was associated with organ function recovery, hemodynamic improvement, and current EAA level reduction in critically ill patients with endotoxic shock. Following propensity score-matched analysis, ICU mortality and 90-day mortalities were lower in the diagnostic-therapeutic flowchart group when considering two temporal groups based on strict patient selection criteria and timing to achieve PMX. Further Randomised Control Trials focused on centre selection, adequate training and a flowchart of action when assessing extracorporeal blood purification use should be performed.

Polymyxin B-immobilised fibre column treatment for acute exacerbation of idiopathic pulmonary fibrosis patients with mechanical ventilation: a nationwide observational study

BackgroundThe prognosis for acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF) is poor, and there is no established treatment. Hence, we aimed to investigate the effectiveness of a polymyxin B-immobilised fibre column (PMX) for the treatment of AE-IPF.MethodsData were retrospectively collected from the Japanese Diagnosis Procedure Combination database from 1 July 2010 to 31 March 2018. We identified adult patients with idiopathic pulmonary fibrosis who received high-dose methylprednisolone (mPSL) therapy and mechanical ventilation upon admission. Eligible patients (n = 5616) were divided into those receiving PMX treatment combined with high-dose mPSL (PMX group, n = 199) and high-dose mPSL alone (mPSL alone group, n = 5417). To compare outcomes between the two groups, we applied a stabilised inverse probability of treatment weighting (IPTW) using propensity scores. The primary outcome was in-hospital mortality, and the secondary outcomes were 14- and 28-day mortality and length of hospital stay.ResultsThe in-hospital mortality rates of the PMX and mPSL alone groups were 79.9% and 76.4%, respectively. The results did not significantly differ between the two groups after performing a stabilised IPTW. The odds ratio of the PMX group compared with the mPSL alone group was 1.56 (95% confidence interval 0.80–3.06; p = 0.19). The 14- and 28-day mortality and length of hospital stay (secondary outcomes) also did not significantly differ between the two groups.ConclusionsIn AE-IPF patients using mechanical ventilation, the treatment outcome was not significantly better for PMX combined with high-dose mPSL than for high-dose mPSL alone.

Loading characteristics of streptavidin on polypropylene capillary channeled polymer fibers and capture performance towards biotinylated proteins.

The development of higher-throughput, potentially lower-cost means to isolate proteins, for a variety of end uses, is of continuing emphasis. Polypropylene (PP) capillary-channeled polymer (C-CP) fiber columns are modified with the biotin-binding protein streptavidin (SAV) to capture biotinylated proteins. The loading characteristics of SAV on fiber supports were determined using breakthrough curves and frontal analysis. Based on adsorption data, a 3-min on-column loading at a flow rate of 0.5 mL min-1 (295.2 cm h-1) with a SAV feed concentration of 0.5 mg mL-1 produces a SAV loading capacity of 1.4 mg g-1 fiber. SAV has an incredibly high affinity for the small-molecule biotin (10-14 M), such that this binding relationship can be exploited by labeling a target protein with biotin via an Avi-tag. To evaluate the capture of the biotinylated proteins on the modified PP surface, the biotinylated versions of bovine serum albumin (b-BSA) and green fluorescent protein (b-GFP) were utilized as probe species. The loading buffer composition and flow rate were optimized towards protein capture. The non-ionic detergent Tween-20 was added to the deposition solutions to minimize non-specific binding. Values of 0.25-0.50% (v/v) Tween-20 in PBS exhibited better capture efficiency, while minimizing the non-specific binding for b-BSA and b-GFP, respectively. The C-CP fiber platform has the potential to provide a fast and low-cost method to capture targeted proteins for applications including protein purification or pull-down assays.

Experimental Investigation on the Impact of Micro-Steel Fibers on the Flat Slabs' Punching Shear Resistance

This research examined the effects of micro-straight steel fiber percentage and column form on the punching shear of SFRC slabs. Fibers made of micro steel with a diameter of 0.2 mm and a length of 13mm with an aspect ratio equal to 65 were used. The fiber content varied between 0.5%, 1%, and 1.5% by volume. Four different types of concrete mixes were adopted and tested. Experimental results showed that when the percentage of steel fibers in SFRC increased, its compressive strength, flexural strength, splitting tensile strength, and direct tensile strength improved. This investigation applied a monotonic load to eight cast slabs (two each of conventional concrete of square and circular column sections of the equivalent area while the other six slabs were made with steel fiber concrete. The dimensions of each slab were (920 x 920 x 80 ) mm. Each slab specimen had essential, edge-based support with square and round column sections. It has been demonstrated that slabs with square column sections endured a relatively higher ultimate load than slabs with circular column segments when the steel fiber dosage was 0.5% or 1.0%. Still, at a steel fiber dosage of 1.5%, circular column segment slabs approached the ultimate load of square column segment slabs. The heterogeneous behavior in concrete can be attributed to the random and unequal distribution of steel fibers throughout the material. There were only flexural fractures visible on the tensile face of the slab. New fractures emerged in the center of the slab as the load increased.

Total Dissolved Solids, Phenol, and Barium Removals from Oilfield Produced Water Using Kapok Fibers and Ultrafiltration Membrane

Oilfield-produced water treatment using raw Kapok fiber (RKF) and a modified surface of Kapok fiber followed by an ultrafiltration membrane was conducted to reduce total dissolved solids (TDS), phenol, and barium. Variables considered in the experiment were contact times (30, 60, 90 min.), the flow rate of samples (5, 6, and 7 L/min), and trans-membrane pressure of ultrafiltration membrane (0.25, 0.35, and 0.50 bar). Raw Kapok fiber and modified surface Kapok fiber were used to investigate the effect of Kapok fiber on total dissolved solids, phenol, and barium removals from produced water. The results showed that raw KF decreased the TDS, phenol, and barium by 51.81%, 62.63%, and 54.20%, respectively. Treatment of raw Kapok fiber column filtrate using ultrafiltration membranes (UF) showed the removal of TDS, barium, and phenol achieved 73.15%, 42.44%, and 79.45%, respectively, at a flow rate of 5 L/min, TMP of 0.25 bar, and contact time of 90 min. Modifying the Kapok fiber surface using sodium hydroxide solution (5 wt%) and hot water (98.5 °C) reduced the TDS, phenol, and barium to 57.32%, 65.83%, and 79.08%, respectively. Further, at the same operating condition, the modified surface of Kapok fiber followed by UF decreased 94.31% TDS, 84.20% phenol, and 56.23% barium, respectively. The results show that modification of the Kapok fiber surface followed by UF can be used to remove the TDS, phenol, and barium from produced water.

Experimental and Numerical Behavior of Basalt Fiber Reinforced Short Concrete Columns Under Axial Loading

This paper presents experimental and numerical investigations to reveal effecting of incorporating basalt fibers into a concrete matrix on the structural behavior and loading capacity of axially loaded short columns. Six volume fractions of chopped basalt fibers are added to the same concrete mixture to prepare six identically reinforced columns. The results illustrate that the bonding forces between microfilaments and matrix increase to provide good internal confinement for concrete ingredients, which enhances compressive strength and column loading capacity. The 0.3 % basalt fiber awarded the best compressive strength, while 0.15 % and 0.3 % awarded the best load capacity to the column. The Addition of basalt fibers delays cracking to increase the cracking load by about 50 % more than no fiber column, which indicates that it needs more energy to overcome the bonding strength between filaments and matrix. At the ultimate state, the loading capacity increases by 15 % and 17 % for 0.15 % and 0.3 % of basalt fibers and by 10 % and 12 % for 0.45% and 0.6% of basalt fiber. The 0.75 % decreased compressive strength by about 6 % but raised the column's ultimate load by 18 %. Therefore, basalt fiber benefits the cracking load more than the maximum load. The finite element showed approaching the peak load in numerical and experimental results. The longitudinal rebars and ties do not yield at the ultimate state. Increasing the reinforcement ratio raises loading capacity while lowering the yield stress of bars minimizes the maximum load.

Effectively recovering catechin compounds in the removal of caffeine from tea polyphenol extract by using hydrophobically modified collagen fiber

Previous research had proved that collagen fiber can be used as separation material for removing caffeine from tea polyphenol extract effectively. But the recovery rate of catechin compounds from collagen fiber column was quite low by using water and ethanol as eluent because of excessively strong hydrogen bond interaction between collagen fiber and polyphenols. To solve the problem, collagen fiber was hydrophobically modified in this work by using silane coupling agents with alkyl chains (butyl, octyl, dodecyl and octadecyl). FT-IR, DSC, SEM and EDS Mapping proved the successful grafting of alkyl chains on collagen fiber, leading to the significantly enhanced hydrophobicity of collagen fiber. Static adsorption showed that the adsorption capacity of EGCG decreased when the grafted alkyl chain length increased mainly relying on the weakened hydrogen bond interaction. Dynamic adsorption and elution behavior also indicated less retention capacity of EGCG on collagen fiber with higher hydrophobicity. In column separation of simulated tea polyphenol extract containing caffeine and catechin compounds, the collagen fiber grafted with octadecyls (CF(C18)) presented excellent separation efficiency for caffeine and catechin compounds, and simultaneously the catechin compounds were highly recovered. The recovery rates of EGC and EGCG were 2–7 times higher than those separated by pristine collagen fiber column and glutaradehyde crosslinked collagen fiber column developed in our previous work. In the reusing round of CF(C18) column, the chromatogram was almost the same as the first round, showing excellent reusability. In fact, the separation performance of CF(C18) to caffeine and catechin compounds was comprehensively superior to Sephadex LH-20, presenting great practical application potential in effectively removing caffeine from tea polyphenol extract and recovering catechin compounds.

Two-dimensional separation of water-soluble polymers using size exclusion and reversed phase chromatography employing capillary-channeled polymer fiber columns

Polymeric materials are readily available, durable materials that have piqued the interest of many diverse fields, ranging from biomedical engineering to construction. The physiochemical properties of a polymer dictate the behavior and function, where large polydispersity among polymer properties can lead to problems; however, current polymer analysis methods often only report results for one particular property. Two-dimensional liquid chromatography (2DLC) applications have become increasingly popular due to the ability to implement two chromatographic modalities in one platform, meaning the ability to simultaneously address multiple physiochemical aspects of a polymer sample, such as functional group content and molar mass. The work presented employs size exclusion chromatography (SEC) and reversed-phase (RP) chromatography, through two coupling strategies: SEC x RP and RP x RP separations of the water-soluble polymers poly(methacrylic acid) (PMA) and polystyrene sulfonic acid (PSSA). Capillary-channeled polymer (C-CP) fiber (polyester and polypropylene) stationary phases were used for the RP separations. Particularly attractive is the fact that they are easily implemented as the second dimension in 2DLC workflows due to their low backpressure (<1000 psi at ∼70 mm sec−1) and fast separation times. In-line multi-angle light scattering (MALS) was also implemented for molecular weight determinations of the polymer samples, with the molecular weight of PMA ranging from 5 × 104 to 2 × 105 g mol−1, while PSSA ranges from 105 to 108 g mol−1. While the orthogonal pairing of SEC x RP addresses polymer sizing and chemistry, this approach is limited by long separation times (80 min), the need for high solute concentrations (PMA = 1.79 mg mL−1 and PSSA = 0.175 mg mL−1 to yield comparable absorbance responses) due to on-column dilution and subsequently limited resolution in the RP separation space. With RP x RP couplings, separation times were significantly reduced (40 min), with lower sample concentrations (0.595 mg mL−1 of PMA and 0.05 mg mL−1 of PSSA) required. The combined RP strategy provided better overall distinction in the chemical distribution of the polymers, yielding 7 distict species versus 3 for the SEC x RP coupling.

Underwater sound absorption characteristic of the rubber core sandwich structure with funnel-shaped cavities reinforced by carbon fiber columns

This paper introduces a multi-functional rubber core sandwich structure with funnel-shaped cavities (RCSSFC) reinforced by carbon fiber columns (CFC), which has the potential to meet requirements of the pressure resistance and acoustic stealth for the underwater equipment in deep sea. A test sample of the RCSSFC with CFC is firstly manufactured and the acoustic propagation experiment is conducted by the pulse tube method to gain the sound absorption coefficient. Then the approximate theoretical model of the RCSSFC is built to predict the sound absorption performance via the layered gradient discretization of cavities, the equivalent theory of the cylindrical tube and the transfer matrix method. Both the obtained experimental and theoretical results are compared with the ones from finite element (FE) analyses conducted in the software COMSOL and the good agreements are achieved. Characteristic analyses are further done to investigate the effects of the diameter of CFC, the shape of cavities, the backing of the structure and the underwater pressure. The design of localized resonances is introduced to improve the low-frequency sound absorption performance. It is found that there are three sound absorption peaks (SAPs) on the curves at lower, middle and higher frequencies, which are respectively dominated by the longitudinal vibration of the structure, the resonances of cavities and the local vibration of the face sheet. Characteristic parameters mainly affect the sound absorption coefficients by changing the above three vibration behaviors. Besides, the CFC greatly improves the pressure resistance property, and the sound absorption performance of the RCSSFC with CFC is insensitive to the change of the pressure. Localized resonances show the excellent effect on increasing the low-frequency sound absorption of the RCSSFC with CFC.