Milestone Studies on Ion-exclusion Chromatography of Ionic and Nonionic Substances Utilizing Multifunctional Separation Mechanism of Ion-exchange Resins

Ion-exclusion chromatography (IEC) is categorized as a type of ion chromatography and is recognized as a simple and convenient water quality monitoring technology for a variety of ionic and nonionic substances. This review, mainly focusing on historical milestone studies by various authors, outlines the archives that concern the separation sciences and practical applications obtained from a variety of IEC modes used for water-quality monitoring as follows: (1) early-developed IEC; (2) IEC using enhanced conductivity detection for weak ionic substance; (3) IEC using nonionic substances eluents such as sugars or polyols; (4) vacancy IEC based on a novel separation concept; (5) applications to the water quality monitoring of inorganic ionic-nutrients; (6) simultaneous IEC and cation-exchange chromatography of anions and cations; and (7) the multicomponent IEC combining different separation modes and detection methods with the expansion of applicable fields, such as for food analysis or material evaluations.

Recent Progress in Ionic Liquid Extraction for the Separation of Rare Earth Elements

This review summarizes recent progress in solvent extraction of rare earth elements (REEs) using an ionic liquid (IL) as the extraction solvent. These IL extraction systems are advantageous owing to the affinity of ILs for both charged and neutral hydrophobic species, in contrast to conventional organic solvent extraction systems. Herein, REE extraction studies using ILs are detailed and classified based on the type of extraction system, namely extraction using anionic ligands, extraction using neutral ligands, synergistic extraction, extraction without extractants, and a specific system using task-specific ionic liquids (TSILs). In IL extraction systems, the extracted complexes are often different from those in organic solvent systems, and the REE extraction and separation efficiencies are often significantly enhanced. Synergistic IL extraction is an effective approach to improving the extractability and separability of REEs. The development of novel TSILs suitable for IL extraction systems is also effective for REE separation.

Recovery of Palladium(II) and Platinum(IV) in Novel Extraction Systems

Recovery of platinum group metals (PGM) from complex aqueous solutions generated as a result of leaching of various spent materials (e.g., spent automotive converters) is a vital issue in the context of the circular economy. In this study pyridinium derivatives containing an imidoamide or imine moiety (i.e., 3-[1-(2-ethylhexyloxyimine)methane]-1-propylpyridinium chloride, 3-[1-(decyloxyimine)methane]-1-propylpyridinium chloride, 3-[1-(decyloxyimine)ethane]-1-propylpyridinium chloride and 4-[1-amine(2-ethylhexyloxyimine)]-1-propylpyridinium chloride) are proposed as novel extractants for recovery of palladium(II) and platinum(IV) from model chloride aqueous solutions. The results of liquid-liquid extraction from one-component solutions of palladium(II) or platinum(IV) showed that quaternary pyridinium salts can be used as effective extractants for platinum metal ions. Moreover, PGM extraction from a two-component mixture proved no evident selectivity in the transfer of one of the metal ions to the organic phase. As the best extractant among the investigated ones, D3EI-PrCl (with straight alkyl chain at substituent) can be pointed out, however, problems with effective stripping or phase disengagement after stripping should be indicated as a drawback of the organic phases used. Further investigation should focus on the improvement of the organic phase properties (e.g., increase in hydrophobicity of the extractants and addition of an organic phase modifier) towards stripping efficiency.

Hydrophilic Surface-Modified PAN Nanofibrous Membranes for Efficient Oil-Water Emulsion Separation

In order to protect the environment, it is important that oily industrial wastewater is degreased before discharging. Membrane filtration is generally preferred for separation of oily wastewater as it does not require any specialised chemical knowledge, and also for its ease of processing, energy efficiency and low maintenance costs. In the present work, hybrid polyacrylonitrile (PAN) nanofibrous membranes were developed for oily wastewater filtration. Membrane surface modification changed nitrile groups on the surface into carboxylic groups, which improve membrane wettability. Subsequently, TiO₂ nanoparticles were grafted onto the modified membranes to increase flux and permeability. Following alkaline treatment (NaOH, KOH) of the hydrolysed PAN nanofibres, membrane water permeability increased two- to eight-fold, while TiO₂ grafted membrane permeability increase two- to thirteen-fold, compared to unmodified membranes. TiO₂ grafted membranes also displayed amphiphilic properties and a decrease in water contact angle from 78.86° to 0°. Our results indicate that modified PAN nanofibrous membranes represent a promising alternative for oily wastewater filtration.

A Decrease in Psycho-Emotional Health in Middle-Aged Russian Women Associated with Their Lifestyle

(1) Background: The present study is aimed to determine the predicting role of objective (lifestyle) and subjective factors of middle-aged women’s psycho-emotional health such as their relations with parents, attachment and separation types. Women who are overloaded with professional and family roles have high stress level, their indicators of psychological well-being and emotional level decrease when they have to give everyday care to their elderly parents. (2) Methods: The research sample has two empirical groups. Sample of Study 1 includes middle-aged women (n = 61) aged 38–56 (M = 48.1, SD = 3.5); sample of Study 2 includes middle-aged women (n = 85) aged 33–52 (M = 40.6, SD = 3.1): married (70.5%) and divorced (29.5%), having children of 14–28 years old; giving everyday care to elderly parents for more than 1.5 yrs. Some live separately (62.3 %), or have to cohabitate with parents (37.7%). All women evaluate their life situation as difficult and manifest signs of high psycho-emotional stress. We used methods adapted for the Russian-speaking sample: getting socio-demographic information, an interview; The scales of psychological well-being; Attachment style and Interpersonal Guilt Questionnaires (study 1); Psychological Separation Inventory, Purpose-in-Life Test, projective methods (study 2), mathematical statistics. (3) Results: A number of factors and indicators of women’s psycho-emotional health decrease in the situation of role overload have been identified. Among the factors there are four main types of women’s relationships with parents: Anxious closeness; Ambivalence of feelings; Secondary relationship with parents; Alienation, predicting of psycho-emotional health that are reducing or enhancing their personal resources. Besides, a type of separation of an adult woman from her mother predicts her level of well-being. (4) Conclusions: The study confirms that middle-aged Russian women’s psycho-emotional health depends on contextual factors (difficult role-overloaded lifestyle) and factors integrating women‘s relations towards parents, attachment, guilt and separation. Types of middle-aged women’s relationships with parents contribute to their psychoemotional health in a different way.

Separation Individuation and Transitional Object Use in Daily Smoker Adolescents

BACKGROUND

Smoking is an important problem in adolescence. Early developmental trajectories are also associated with cigarette smoking.

OBJECTIVES

The present study aims to evaluate the separation-individuation process and use of transitional objects in daily smoker adolescents.

METHOD

The research included 97 adolescents who were daily smokers and 210 adolescents who were nonsmokers. Transitional object assessment questionnaire, strength and difficulties questionnaire- adolescent form(SDQ), children's depression inventory(CDI) and state-trait anxiety inventory for children(STAI-C), separation and individuation test of adolescence(SITA) were applied.

RESULTS

SITA subscales scores of engulfment anxiety, need denial, and rejection expectancy was higher and separation anxiety, teacher enmeshment, nurturance seeking scores were statistically significantly lower in smoker adolescents than nonsmokers. In logistic regression analysis, separation anxiety(odds ratio [OR] 0.93; 95% confidence interval[CI] 0.87-0.98), teacher enmeshment(OR 0.93; 95% CI 0.88-0.98), practicing mirroring(OR 1.05; 95% CI 1.02,1.08) and rejection expectancy (OR 1.06 95% CI 1.02,1.11) were found to be predictors of daily smoking. The use of a childhood transitional object for feeling tired and the use of an adolescent transitional object for feeling anxious and tired was found to be significantly higher in smokers.

CONCLUSIONS

There are some differences in the process of separation-individuation and the use of transitional objects in the smoker group. This suggests that early developmental characteristics may be associated with smoking. Further studies are needed to better understand the causal relationship between smoking and the separation-individuation process and transitional object use.

Impact of incubation conditions and post-treatment on the properties of bacterial cellulose membranes for pressure-driven filtration

Bacterial cellulose (BC) has shown potential as a separation material. Herein, the performance of BC in pressure-driven separation is investigated as a function of incubation conditions and post-culture treatment. The pure water flux of never-dried BC (NDBC), was found to be 9 to 16 times higher than that for dried BC (DBC), in a pressure range of 0.25 to 2.5 bar. The difference in pressure response of NDBC and DBC was observed both in cross-flow filtration and capillary flow porometry experiments. DBC and NDBC were permeable to polymers with a hydrodynamic radius of ∼60 nm while protein retention was possible by introducing anionic surface charges on BC. The results of this work are expected to expand the development of BC-based filtration membranes, for instance towards the processing of biological fluids.

Separation of constituents from Bergenia stracheyi (Hook. F. & Thoms.) Engl. by high-speed countercurrent chromatography with elution mode and its antidiabetic and antioxidant in vitro evaluation

Diabetes, a metabolic disorder, is caused by a high blood sugar level. Diabetes is an increasing health issue and search for potent antidiabetic agents is desirable. Owing to its ethnomedicinal value, the Himalayan perennial herb Bergenia stracheyi (Hook. f. & Thoms.) Engl. (Saxifragaceae Juss) is used to treat diabetes. Herein, an efficient high-speed countercurrent chromatography with elution mode is reported for separation of active compounds from B. stracheyi. In current investigation, six main compounds including β-arbutin (1), bergenin (2), 6-O-galloylarbutin (3), gallic acid (4), 11-O-galloylbergenin (5), and (-)-epicatechin 3-O-gallate (6) with above 95% purity were efficiently separated in a single run using biphasic tert-butyl methyl ether/n-butanol/methanol/water (1:3:1:5, v/v/v/v) solvent system. The structures of these compounds were characterized using spectral techniques and compared with the literature. Antidiabetic and antioxidant activities evaluation of the study samples showed that β-arbutin (1) and 6-O-galloylarbutin (3) have a significant protective effect, especially at high dose against hydrogen peroxide induced oxidative injury. Our results might help further in-depth phytochemical and biological evaluation studies in search of potent antidiabetic compounds from B. stracheyi.

Surface Engineering of Ceramic Nanomaterials for Separation of Oil/Water Mixtures

Oil/water mixtures are a potentially major source of environmental pollution if efficient separation technology is not employed during processing. A large volume of oil/water mixtures is produced via many manufacturing operations in food, petrochemical, mining, and metal industries and can be exposed to water sources on a regular basis. To date, several techniques are used in practice to deal with industrial oil/water mixtures and oil spills such as in situ burning of oil, bioremediation, and solidifiers, which change the physical shape of oil as a result of chemical interaction. Physical separation of oil/water mixtures is in industrial practice; however, the existing technologies to do so often require either dissipation of large amounts of energy (such as in cyclones and hydrocyclones) or large residence times or inventories of fluids (such as in decanters). Recently, materials with selective wettability have gained attention for application in separation of oil/water mixtures and surfactant stabilized emulsions. For example, a superhydrophobic material is selectively wettable toward oil while having a poor affinity for the aqueous phase; therefore, a superhydrophobic porous material can easily adsorb the oil while completely rejecting the water from an oil/water mixture, thus physically separating the two components. The ease of separation, low cost, and low-energy requirements are some of the other advantages offered by these materials over existing practices of oil/water separation. The present review aims to focus on the surface engineering aspects to achieve selectively wettability in materials and its their relationship with the separation of oil/water mixtures with particular focus on emulsions, on factors contributing to their stability, and on how wettability can be helpful in their separation. Finally, the challenges in application of superwettable materials will be highlighted, and potential solutions to improve the application of these materials will be put forward.

Quality Assessment and Comparison of Plasma-Derived Extracellular Vesicles Separated by Three Commercial Kits for Prostate Cancer Diagnosis

Introduction

Current standard biomarkers in clinic are not specific enough for prostate cancer (PCa) diagnosis. Extracellular vesicles (EVs) are nano-scale vesicles released by most mammalian cells. EVs are promising biomarker source for PCa liquid biopsy due to its minimal invasive approach, rich information and improved accuracy compared to the clinical standard prostate-specific antigen (PSA). However, current EV separation methods cannot separate pure EVs and the quality characteristics from these methods remain largely unknown. In this study, we evaluated the quality characteristics of human plasma-derived EVs by comparing three clinical suitable separation kits.

Methods

We combined EV separation by commercial kits with magnetic beads capture and flow cytometry analysis, and compared three kits including ExoQuick Ultra based on precipitation and qEV35 and qEV70 based on size exclusion chromatography (SEC).

Results

Our results indicated that two SEC kits provided higher EV purity and lower protein contamination compared to ExoQuick Ultra precipitation and that qEV35 demonstrated a higher EV yield but lower EV purity compared to qEV70. Particle number correlated very well particularly with CD9/81/63 positive EVs for all three kits, which confirms that particle number can be used as the estimate for EV amount. At last, we found that several EV metrics including total EVs and PSA-specific EVs could not differentiate PCa patients from health controls.

Conclusion

We provided a systematic workflow for the comparison of three separation kits as well as a general analysis process in clinical laboratories for EV-based cancer diagnosis. Better EV-associated cancer biomarkers need to be explored in the future study with a larger cohort.

Dielectrophoresis-field flow fractionation for separation of particles: A critical review

Dielectrophoresis-field flow fractionation (DEP-FFF) has emerged as an efficient in-vitro, non-invasive, and label-free mechanism to manipulate a variety of nano- and micro-scaled particles in a continuous-flow manner. The technique is mainly used to fractionate particles/cells based on differences in their sizes and/or dielectric properties by employing dielectrophoretic force as an external force field applied perpendicular to the flow direction. The dielectrophoretic force is the result of a spatially non-uniform electric field in the microchannel that can be generated either by exploiting microchannel geometry or using special arrangements of microelectrode arrays. Several two-dimensional (e.g., coplanar interdigitated, castellated) and three-dimensional (e.g., top-bottom, side-wall) microelectrode designs have been successfully utilized to perform fractionation of heterogeneous samples. Although originally introduced as a separation technique, DEP-FFF has attracted increasing interest in performing other important operations such as switching, focusing, dipping, and surface functionalization of target particles. Nonetheless, the technique still suffers from limitations such as low throughput and joule heating. By comparatively analyzing recent developments that address these shortcomings, this work is a step forward towards realizing the full potential of DEP-FFF as an ideal candidate for point-of-care (POC) devices with diverse applications in the fields of biomedical, chemical, and environmental engineering.

Isolable 1-Butene Copper(I) Complexes and 1-Butene/Butane Separation Using Structurally Adaptable Copper Pyrazolates

Non-porous small molecule adsorbents such as {[3,5-(CF₃ )₂ Pz]Cu}₃ (where Pz=pyrazolate) are an emerging class of materials that display attractive features for ethene-ethane separation. This work examines the chemistry of fluorinated copper(I) pyrazolates {[3,5-(CF₃ )₂ Pz]Cu}₃ and {[4-Br-3,5-(CF₃ )₂ Pz]Cu}₃ with much larger 1-butene in both solution and solid state, and reports the isolation of rare 1-butene complexes of copper(I), {[3,5-(CF₃ )₂ Pz]Cu(H₂ C=CHC₂ H₅ )}₂ and {[4-Br-3,5-(CF₃ )₂ Pz]Cu(H₂ C=CHC₂ H₅ )}₂ and their structural, spectroscopic, and computational data. The copper-butene adduct formation in solution involves olefin-induced structural transformation of trinuclear copper(I) pyrazolates to dinuclear mixed-ligand systems. Remarkably, larger 1-butene is able to penetrate the dense solid material and to coordinate with copper(I) ions at high molar occupancy. A comparison to analogous ethene and propene complexes of copper(I) is also provided.

Aqueous Two-Phase System (ATPS)-Based Polymersomes for Particle Isolation and Separation

Aqueous two-phase systems (ATPSs) have been widely used in the separation, purification, and enrichment of biomolecules for their excellent biocompatibility. While ultracentrifugation and microfluidic devices have been combined with ATPS to facilitate the separation of biomolecules and achieve high recovery yields, they often lack the ability to effectively isolate and separate biomolecules in low concentrations. In this work, we present a strategy that leverages the preferential partitioning of biomolecules in ATPS droplets to efficiently separate model extracellular vesicle (EV) particles. We demonstrate that the additional oil phase between the inner ATPS droplets and the aqueous continuous phase in triple emulsion droplets resolves the size controllability and instability issues of ATPS droplets, enabling the production of highly monodisperse ATPS-based polymersomes with enhanced stability for effective isolation of ATPS droplets from the surrounding environment. Furthermore, we achieve separation of model EV particles in a single dextran (DEX)-rich droplet by the massive production of ATPS-based polymersomes and osmotic-pressure-induced rupture of the selected polymersome in a hypertonic solution composed of poly(ethylene glycol) (PEG).

Mother-child separation among women living with HIV and their children in the first four years postpartum in South Africa

OBJECTIVES

Mother-child pairs may separate during early life, yet the health impacts thereof are unclear. We explored the patterns and impact of separation among women living with HIV (WLHIV) and their children in South Africa.

METHODS

WLHIV who had initiated antiretroviral therapy (ART) during pregnancy received HIV viral load (VL) testing and completed a timeline questionnaire of mother-child separation since delivery at 3-5 years post-partum. Health care usage was abstracted from routine medical records. We examined associations between separation and (a) maternal health outcomes (engagement in HIV care and HIV viral suppression, [VS]) and (b) child health outcomes (post-breastfeeding HIV testing and immunisation completion), using logistic regression.

RESULTS

Of 346 mother-child pairs (median maternal age at antenatal ART initiation, 28 years), 24% were ever separated (median time to first separation 20 months, interquartile range [IQR] 9, 31). Most separated children were living with their grandmothers (65/83, 78%). Mothers who ever separated were younger, and more likely to be employed, and to reside in informal housing than those who never separated. Any separation reduced the odds of VS ≤ 50 copies/mL at four years post-partum (odds ratio 0.57; 95% CI 0.34-0.93); associations were similar for VL ≤ 1000 copies/mL and maternal engagement in care. No association was found between separation and child confirmatory HIV testing or immunisation completion.

CONCLUSIONS

In this setting, mother-child separation is common in the first four years of life and appears associated with suboptimal maternal outcomes. Further research is required to understand the drivers and implications of mother-child separation.

Mathematical Quantification of Transmission in Experiments: FMDV Transmission in Pigs Can Be Blocked by Vaccination and Separation

Quantitative understanding of transmission with and without control measures is important for the control of infectious diseases because it helps to determine which of these measures (or combinations thereof) will be effective to reduce transmission. In this paper, the statistical methods used to estimate transmission parameters are explained. To show how these methods can be used we reviewed literature for papers describing foot-and-mouth disease virus (FMDV) transmission in pigs and we used the data to estimate transmission parameters. The analysis showed that FMDV transmits very well when pigs have direct contact. Transmission, however, is reduced when a physical barrier separates infected and susceptible non-vaccinated pigs. Vaccination of pigs can prevent infection when virus is administered by a single intradermal virus injection in the bulb of the heel, but it cannot prevent infection when pigs are directly exposed to either non-vaccinated or vaccinated FMDV infected pigs. Physical separation combined with vaccination is observed to block transmission. Vaccination and separation can make a significant difference in the estimated number of new infections per day. Experimental transmission studies show that the combined effect of vaccination and physical separation can significantly reduce transmission (R < 1), which is a very relevant result for the control of between-farm transmission.

Computer-Aided Design of Boron Nitride-Based Membranes with Armchair and Zigzag Nanopores for Efficient Water Desalination

Recent studies have shown that the use of membranes based on artificial nanoporous materials can be effective for desalination and decontamination of water, separation of ions and gases as well as for solutions to other related problems. Before the expensive stages of synthesis and experimental testing, the search of the optimal dimensions and geometry of nanopores for the water desalination membranes can be done using computer-aided design. In the present study, we propose and examine the assumption that rectangular nanopores with a high aspect ratio would demonstrate excellent properties in terms of water permeation rate and ion rejection. Using the non-equilibrium molecular dynamic simulations, the properties of promising hexagonal boron nitride (h-BN) membranes with rectangular nanopores were predicted. It has been found that not only the nanopore width but also its design (“armchair” or “zigzag”) determines the permeability and ion selectivity of the h-BN-based membrane. The results show that membranes with a zigzag-like design of nanopores of ~6.5 Å width and the armchair-like nanopores of ~7.5 Å width possess better efficiency compared with other considered geometries. Moreover, the estimated efficiency of these membranes is higher than that of any commercial membranes and many other previously studied single-layer model membranes with other designs of the nanopores.

Covalent Organic Framework Composites: Synthesis and Analytical Applications

In the recent years, composite materials containing covalent organic frameworks (COFs) have raised increasing interest for analytical applications. To date, various synthesis techniques have emerged that allow for the preparation of crystalline and porous COF composites with various materials. Herein, we summarize the most common methods used to gain access to crystalline COF composites with magnetic nanoparticles, other oxide materials, graphene and graphene oxide, and metal nanoparticles. Additionally, some examples of stainless steel, polymer, and metal-organic framework composites are presented. Thereafter, we discuss the use of these composites for chromatographic separation, environmental remediation, and sensing.

Enhancing Selective Adsorption in a Robust Pillared-Layer Metal-Organic Framework via Channel Methylation for the Recovery of C2-C3 from Natural Gas

Here, we reported a strategy for channel methylation to construct a robust ultramicroporous metal-organic framework (MOF) Ni(TMBDC)(DABCO)_0.5 through hydrothermal synthesis method and investigated its adsorption performance for recovering ethane (C₂) and propane (C₃) from natural gas. The as-synthesized Ni(TMBDC)(DABCO)_0.5 featured ultramicroporosity with a uniform pore size of 0.5 nm. The resulting sample showed a strong adsorption interaction with C₃H₈ and C₂H₆, and its C₃H₈ adsorption capacity at a low pressure of 1 kPa was up to 2.80 mmol/g and its C₂H₆ adsorption capacity at a low pressure of 10 kPa reached as high as 2.93 mmol/g, exhibiting strong binding affinity for ethane and propane. The enhanced adsorption can be attributed to the presence of the dense and accessible methyl and methylene groups in the channels of the sample. Grand Canonical Monte Carlo (GCMC) simulations also confirmed that the methylene groups from the DABCO pillar and the methyl groups from the TMBDC ligand play an important role in enhancing the adsorption of ethane and propane. Its ideal adsorbed solution theory (IAST)-predicted selectivity of C₂H₆/CH₄ reached unprecedentedly 29, much higher than most of the reported data for MOFs. The stability test confirmed that the crystal structure of Ni(TMBDC)(DABCO)_0.5 still remained intact after it was exposed to moist air with a relative humidity of 100% for days. The breakthrough experiment demonstrated that the CH₄/C₂H₆/C₃H₈ ternary mixture was completely separated using a fixed bed of Ni(TMBDC)(DABCO)_0.5 at ambient temperature, showing a great potential for recovering the low content of ethane and propane from natural gas.

Design and Preparation of Molecularly Imprinted Membranes for Selective Separation of Acteoside

Acteoside (ACT) belongs to a type of phenylethanoid glycosides (PhGs), and it is worthy of obtaining high-purity due to its significant medicinal functions. In this study, a novel class of MIMs was designed and synthesized with PVDF membranes as the base membrane for high selective separation and enrichment of ACT. The effects of the different functional monomers, the amounts of functional monomers, crosslinking agents, and initiators on the separation properties of MIMs were investigated. Furthermore, adsorption ability, permeation capacity, and reusability of MIMs were discussed for ACT. It indicated that MIM7 was the optimal performance of MIMs. The adsorption ability of MIM7 for ACT was 62.83 mg/g, and the selectivity factor (α) of MIM7 was up to 2.74 and its permeability factor (β) was greater than 2.66. Moreover, the adsorption amount of MIM7 was still more than 88.57% of the initial value after five cycles. As an ACT imprinted layer of MIMs only had recognition sites for ACT molecules, which recombined with the recognition sites in the membrane permeation experiment, ACT molecules penetration was hindered. However, the analogs of ECH successfully passed MIMs. It indicated that the selective MIMs for ACT followed the mechanism of delayed permeation. This work provides an important reference for the high permselective separation of natural products.

Controlling the Structure of MoS2 Membranes via Covalent Functionalization with Molecular Spacers

Restacked two-dimensional (2D) materials represent a new class of membranes for water-ion separations. Understanding the interplay between the 2D membrane's structure and the constituent material's surface chemistry to its ion sieving properties is crucial for further membrane development. Here, we reveal, and tune via covalent functionalization, the structure of MoS₂-based membranes. We find features on both the ∼1 nm (interlayer spacing) and ∼100 nm (mesoporous voids between layers) length scales that evolve with the hydration level. The functional groups act as permanent molecular spacers, preventing local impermeability caused by irreversible restacking and promoting the uniform rehydration of the membrane. Molecular dynamics simulations show that the choice of functional group tunes the structure of water within the MoS₂ channel and consequently determines the hydrated interlayer spacing. We demonstrate that MoS₂ membranes functionalized with acetic acid have consistently ∼92% rejection of Na₂SO₄ with a flux of ∼1.5 lm^-2 hr^-1 bar^-1.

Doubly Interpenetrated Metal-Organic Framework of pcu Topology for Selective Separation of Propylene from Propane

Adsorptive separation is an appealing alternative technology to reduce the high energy and capital cost of the distillation separation of propylene/propane; however, it is very challenging to realize. A new flexible metal-organic framework (MOF) material [Zn₂(BDC-Cl)₂(Py₂TTz)] with a doubly interpenetrated pillared paddle wheel structure of pcu (primitive cubic) topology has been realized for this difficult separation for the first time. Through a judicious choice of linkers, the framework has small pore apertures that lead to much more propylene adsorption than propane. The selective adsorption relies on the sieving effect of the flexible framework. The column breakthrough experiment further demonstrated that efficient separation can be achieved under dynamic conditions.

Unusually Low Heat of Adsorption of CO2 on AlPO and SAPO Molecular Sieves

The capture of CO₂ from post-combustion streams or from other mixtures, such as natural gas, is an effective way of reducing CO₂ emissions, which contribute to the greenhouse effect in the atmosphere. One of the developing technologies for this purpose is physisorption on selective solid adsorbents. The ideal adsorbents are selective toward CO₂, have a large adsorption capacity at atmospheric pressure and are easily regenerated, resulting in high working capacity. Therefore, adsorbents combining molecular sieving properties and low heats of adsorption of CO₂ are of clear interest as they will provide high selectivities and regenerabilities in CO₂ separation process. Here we report that some aluminophosphate (AlPO) and silicoaluminophosphate (SAPO) materials with LTA, CHA and AFI structures present lower heats of adsorption of CO₂ (13-25 kJ/mol) than their structurally analogous zeolites at comparable framework charges. In some cases, their heats of adsorption are even lower than those of pure silica composition (20-25 kJ/mol). This could mean a great improvement in the regeneration process compared to the most frequently used zeolitic adsorbents for this application while maintaining most of their adsorption capacity, if materials with the right stability and pore size and topology are found.

Evaluation of Forensic Data Using Logistic Regression-Based Classification Methods and an R Shiny Implementation

We demonstrate the use of classification methods that are well-suited for forensic toxicology applications. The methods are based on penalized logistic regression, can be employed when separation occurs in a two-class classification setting, and allow for the calculation of likelihood ratios. A case study of this framework is demonstrated on alcohol biomarker data for classifying chronic alcohol drinkers. The approach can be extended to applications in the fields of analytical and forensic chemistry, where it is a common feature to have a large number of biomarkers, and allows for flexibility in model assumptions such as multivariate normality. While some penalized regression methods have been introduced previously in forensic applications, our study is meant to encourage practitioners to use these powerful methods more widely. As such, based upon our proof-of-concept studies, we also introduce an R Shiny online tool with an intuitive interface able to perform several classification methods. We anticipate that this open-source and free-of-charge application will provide a powerful and dynamic tool to infer the LR value in case of classification tasks.

[Mass transport properties and applications of nanochannels]

With the development of materials science, micro/nano processing technologies, and mass transport theories at the micro/nano scale, nanochannel-based technology has been receiving increasing attention. Nanochannels can be classified as biological and artificial. The size of a nanochannel is typically 1-100 nm, which greatly enhances the interaction between the channel surface and substances inside the channel, inducing several special mass transport properties such as ion selectivity, ionic current rectification, and resistive current pulse. Ion selectivity is caused by the electrostatic interaction between ions and the surface charge of the nanochannel, ionic current rectification arises from the asymmetric distribution of the electrochemical potential inside the nanochannel, and a resistive current pulse is generated by the blocking of the nanochannel during the transport of ions/molecules. By taking advantage of these mass transport properties, nanochannels can be applied to various fields. For example, gated ion transport can be realized by modifying the surface of the nanochannel with functional groups; single-molecule sensing can be realized using sub-nanoscale channels; the separation of ions, molecules, or nanoparticles can be realized by regulating the interaction between the nanochannel and transport substances; and various forms of energy, such as light, heat, and salt gradient, can drive charge separation within the nanochannel and be converted into electricity by harnessing the ion selectivity of the nanochannel. However, despite the achievements in nanochannel-based technology, in-depth exploration of the mass transport properties at the nanoscale and further expansion of its application remain to be realized. For the development of this technology, four major issues need to be addressed: fabrication of a single-atom-thick nanochannel/nanopore membrane, precise control of the nanochannel structure, effective regulation of the surface properties of the nanochannel, and enrichment and development of mass transport theories. Nanochannel-based technology requires interdisciplinary efforts at the intersection of chemistry, materials science, and nanotechnology, and shows good promise for solving basic problems in biology, environment, and energy. Herein, we briefly describe the mass transport properties of nanochannels and some emerging developments and applications, and finally provide a brief outlook on this field.

Novel Approach toward Electrofluidic Substrates Utilizing Textile-Based Braided Structure

Electrofluidics is the unique combination of electrophoresis and microfluidics, which has opened up broad opportunities for bioanalysis and multiplexed assay. These systems typically comprise inaccessible and fully enclosed microcapillary or microchannels, with limited sample loading capacities and no direct access to the solutes within. Here, we investigate the application of multiyarn textile assemblies which provides an open and surface accessible electrophoretic separation platform. Three-dimensional (3D) textile structures have been produced using conventional knitting and braiding techniques from a range of commercially available yarns. Capillary zone electrophoresis separation studies have been carried out on these substrates using fluorescent anionic (fluorescence, FL) and cationic (rhodamine-B, Rh-B) markers. The effects of different yarn surface chemistry, textile fabrication technique, and electrolyte ionic strength on the electrophoretic mobility of the test analytes have been studied. From the broad range of yarns investigated, polyester was shown to have the highest electrophoretic mobility for Rh-B (6 × 10^-4 cm² V^-1 s^-1) and for FL (4 × 10^-4 cm² V^-1 s^-1). The braiding approach, being simple and versatile, was found to be the most effective route to produce 3D textile-based structures and offered the potential for selective movement and targeted delivery to different channels. Composite braids made with yarns of differential surface chemistries further revealed a unique behavior of separation and parallel movement of oppositely charged ionic species. We also demonstrate the feasibility to apply isotachophoresis (ITP) on these braided textile substrates to rapidly focus dispersed FL sample bands. Here, we demonstrate the focusing of FL from a dispersed band into narrow band with a 400 times reduction in sample width over 90 s. Owing to the simplicity and reproducibility of the developed approach, textile-based inverted microfluidic applications are expected to enable opportunities in bioanalysis, proteomics, and rapid clinical diagnostics.