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Endothelial dysfunction caused by persistent hyperglycemia in diabetes is responsible for impaired angiogenesis in diabetic wounds. Extracellular vehicles (EVs) are considered potential therapeutic tools to promote diabetic wound healing. The aim of this study was to investigate the effects of EVs secreted by human umbilical cord mesenchymal stem cells (hucMSC-EVs) on angiogenesis under high glucose (HG) conditions in vivo and in vitro and to explore the underlying mechanisms. In vivo, local application of hucMSC-EVs enhanced wound healing and angiogenesis. In vitro, hucMSC-EVs promoted proliferation, migration, and tube formation by inhibiting phosphatase and tensin homolog (PTEN) expression and activating the AKT/HIF-1α/VEGF pathways. MiR-17-5p was found to be highly enriched in hucMSC-EVs. In vitro, MiR-17-5p agomirs downregulated the expression of PTEN and activated the AKT/HIF-1α/VEGF pathway to promote proliferation, migration, and tube formation in HG-treated HUVECs. In vivo, miR-17-5p agomirs mimicked the effects of hucMSC-EVs on wound healing and angiogenesis, whereas miR-17-5p inhibitors reversed their effects. Our findings suggest that hucMSC-EVs have regenerative and protective effects on HG-induced endothelial cells via transfer of miR-17-5p targeting PTEN/ AKT/HIF-1α/VEGF pathway, thereby accelerating diabetic wound healing. Thus, hucMSC-EVs may be promising therapeutic candidates for improving diabetic wound angiogenesis.

Diabetic wounds are a common complication of diabetes and therefore a pressing issue for clinicians. High-glucose (HG)-induced fibroblast senescence is mainly responsible for delayed wound healing. Calcium silicate (CS), a kind of bioceramic, is thought to have regenerative properties. The aim of this study was to determine the regenerative and protective effects of CS on senescent fibroblasts induced by HG. Fibroblasts were passaged five times and treated with HG and CS. Compared with the normal glucose (NG) group, the proliferation, migration, and differentiation capacity of HG-induced fibroblasts significantly decreased (P < .05). After treatment with CS, the functions of HG-induced senescent fibroblasts were partly restored (P < .05). The mechanism of the regenerative and protective effects of CS may be related to the decreased reactive oxygen species generation, improved senescent state (SA-β-gal expression decreased), up-regulated expression of Smad2 and phosphorylated Smad2, and down-regulated expression of p16, p21, and p53. An in vivo experiment also demonstrated that CS had a therapeutic effect on diabetic wounds via differentiation of fibroblasts into myofibroblasts and enhanced collagen deposition. These results indicate that CS may be a promising candidate for diabetic wound therapy.

Endothelial malfunction is responsible for impaired angiogenesis in diabetic patients, thereby causing the delayed healing progress of diabetic wounds. Exosomes or extracellular vesicles (EVs) have emerged as potential therapeutic vectors carrying drug cargoes to diseased cells. In the present study, EVs were reported as a new treatment for diabetic wounds by delivering VH298 into endothelial cells. Firstly, EVs derived from epidermal stem cells (ESCs) were loaded with VH298 (VH-EVs), and the characteristics of VH-EVs were identified. VH-EVs showed promotive action on the function of human umbilical vein endothelial cells (HUVECs) in vitro by activating HIF-1α signaling pathway. VH-EVs were also found to have a therapeutic effect on wound healing and angiogenesis in vivo. We further fabricated gelatin methacryloyl (GelMA) hydrogel for sustained release of VH-EVs, which possessed high biocompatibility and proper mechanical properties. In diabetic mice, GelMA hydrogel containing VH-EVs (Gel-VH-EVs) effectively promoted wound healing by locally enhancing blood supply and angiogenesis. The underlying mechanism for enhanced angiogenesis was possibly associated with the activation of HIF-1α/VEGFA signaling pathway. Collectively, our findings suggest a promising EV-based strategy for the VH298 delivery to endothelial cells and provide a new bioactive dressing for diabetic wound treatment. STATEMENT OF SIGNIFICANCE: The angiogenic dysfunction is the main cause of diabetic wound unhealing. Extracellular vesicles (EVs) have been reported to be helpful but their efficacy is limited for angiogenesis in cutaneous regeneration. VH298 holds great promise to improve angiogenesis by stabilizing HIF-1α which is reported at low level in diabetic wounds. Here, we loaded EVs with VH298 (VH-EVs) to exert an on-target enhancement of proangiogenic capacity in diabetic wound. Then, we applied a photo-crosslinkable hydrogel, gelatin methacryloyl (GelMA) containing VH-EVs (Gel-VH-EVs) as a convenient biomaterial and an adaptable scaffold for sustained releasing VH-EVs. The results showed significant therapeutic effect of Gel-VH-EVs on skin defect repair. Our findings suggest a promising EVs-based drug delivery strategy and a new functional wound dressing for patients.

The poor formability of aluminum alloys at room temperature easily leads to quality defects such as ruptures, wrinkles and excessive springback after forming, which severely restricts their wide application in the automotive industry. In this article, a combination of springback compensation and process parameter optimization is proposed to improve the forming quality of aluminum alloy auto body panels. First, the springback compensation for the tooling setting was conducted using the global shape modeling (GSM) function in ThinkDesign to ensure the desired dimensional quality of the hood. Then, the process parameter optimization was conducted based on the combination of a back-propagation (BP) neural network and genetic algorithm (GA) method to improve formability. After springback compensation and process parameter optimization, the obtained product could satisfy the matching requirements well. A case study of an AA5182-O aluminum alloy engine hood inner panel is presented. The experiments demonstrate that the combination of the springback compensation and the optimization scheme based on the BP neural network and GA can effectively improve the product’s forming quality.

With the continued focus on in-depth investigations of hair follicle stem cells (HFSCs), the role of HFSCs in wound healing has attracted increasing attention from researchers. This review may afford meaningful implications for HFSC treatment of wounds.We present the properties of HFSCs, analyze the possibility of HFSCs in wound healing, and sum up the recent studies into wound repair with HFSCs. The details of HFSCs in wound healing have been discussed. The possible mechanisms of wound healing with HFSCs have been elaborated. Additionally, the factors that influence HFSCs in wound healing are also summarized.Hair follicle stem cells are promising sources for wound healing. However, a further understanding of human HFSCs and the safety use of HFSCs in clinical practice still remain in relative infancy.

Background: Endothelial dysfunction caused by persistent hyperglycemia in diabetes is responsible for impaired angiogenesis in diabetic wounds. Exosomes are considered potential therapeutic tools to promote diabetic wound healing. The aim of this study was to investigate the effects of exosomes secreted by human umbilical cord mesenchymal stem cells (hucMSC-Exos) on angiogenesis under high glucose (HG) conditions in vivo and in vitro and to explore the underlying mechanisms.Methods: HucMSC-Exos were used to treat diabetic wounds and human umbilical vascular endothelial cells (HUVECs) exposed to HG. Wound healing and angiogenesis were assessed in vivo. The biological characteristics of HUVECs were examined in vitro. Expression of pro-angiogenesis genes in HUVECs was also examined by western blotting. The miRNAs contained within hucMSC-Exos were identified using miRNA microarrays and qRT-PCR. The roles of selected miRNAs in angiogenesis were assessed using specific agomirs and inhibitors.Results: In vivo, local application of hucMSC-Exos enhanced wound healing and angiogenesis. In vitro, hucMSC-Exos reduced senescence of HG-treated HUVECs and promoted proliferation, migration, and tube formation by inhibiting phosphatase and tensin homolog (PTEN) expression and activating the AKT/HIF-1α/VEGF pathways. MiR-221-3p was enriched in hucMSC-Exos. In vitro, MiR-221-3p downregulated PTEN and activated the AKT/HIF-1α/VEGF pathway to promote proliferation, migration, and tube formation in HG-treated HUVECs. In vivo, miR-221-3p agomirs mimicked the effects of hucMSC-Exos on wound healing and angiogenesis, whereas miR-221-3p inhibitors reversed their effects.Conclusions: Our findings suggest that hucMSC-Exos have regenerative and protective effects on HG-induced senescence in endothelial cells via transfer of miR-221-3p, thereby accelerating diabetic wound healing. Thus, hucMSC-Exos may be promising therapeutic candidates for improving diabetic wound angiogenesis.

Fighting on the frontlines against the coronavirus disease 2019 (COVID-19) pandemic, health workers are at high risk of virus infection and overwork-related sudden death and disorders including cardiovascular diseases and stress. When we noted the increase of overwork-related sudden deaths in physicians and nurses in the first 2 weeks after lockdown of Wuhan, we organized the ‘Touching Your Heart’ program by remote monitoring, aiming to protect health workers from overwork-related disorders through integrated volunteer work by physicians and medical engineering researchers from Wuhan Huoshenshan Hospital, Nanjing Medical University, and Tiangong University. By remotely monitoring the health conditions of the medical aid team working at Wuhan Huoshenshan Hospital, the program successfully helped in avoiding severe overwork-related events. The results from our program should be used to remind frontline health workers around the world to take precautions against overworked-related severe events, and show that precision monitoring is effective in improving work efficiency and maintaining a sustainable workforce during emergency situations like a pandemic.

Vitiligo is a common depigment of skin disorder due to loss of functional melanocytes. Recently, the phototherapy with a 308-nm xenon-chloride excimer laser (UVB laser) is wildly used in vitiligo treatment. However, excessive UVB will induce photo-damage and photo-carcinogenesis in melanocytes. Previous studies revealed a protective effect of heat on UVB-induced melanocyte damage. In this study, we combined heat stress pretreatment with UVB to evaluate whether heat stress pretreatment has an ameliorative effect on UVB-induced damage. Human primary melanocytes (HMCs) were cultured and irradiated with a 308-nm laser with/without heat treatment. MTT assay, apoptosis analysis, and comet assay were conducted to monitor the damage of HMCs. Western blot and immunofluorescence staining were performed to assess the expression and subcellular localization of HSP70. HMCs heated at 42 °C for 1 h exhibit no cytotoxicity. Furthermore, preheat treatment attenuated the UVB laser-induced injury, reduced the DNA damage, and attenuated the cell apoptosis. The level and the localization of HSP70 determined the protective effects against UVB-induced DNA damage. Combining preheat treatment with a 308-nm xenon-chloride excimer laser would be a potential therapeutic method not only promotes the repigment of vitiligo but also reduces the UVB-induced photo-damage.

Increasing studies demonstrated that photobiomodulation (PBM) influenced specific biological effects in cells, tissues and organs, and these effects rely on the production of light irradiation. In this study, we aimed to precisely manipulate the spatial arrangement of adhesion cells in a traditional culture condition with 450 nm low intensity laser. Through 450 nm laser PBM, the adhesion of the cultured cells was significantly improved and resisted the digestion of 0.1% trypsin. Combined with a computer aided design system (CAD) and computer numerical control (CNC) system, the designed laser irradiation pattern induced the specific cell micropattern in the culture dish. RNA sequencing and biochemical experiments confirmed that the 450 nm laser prompted low-density lipoprotein (LDL) bonding to the cell surface and induced lipid peroxidation, which crosslinked and modified the protein molecules on the irradiated cell surface. In this way, the peroxidation product-modified proteins resisted trypsin proteolysis, ultimately leading to a differential detachment between the irradiated and non-irradiated cells under trypsin treatment. This convenient method did not require special biomaterial processing, has no impact on cell viability and functions, and required no changes to the conventional cell culture conditions. The photo-induced cell capturing is a great complement to existing tools by providing spatial resolution.

One of the most crucial branches of regenerative medicine is cell therapy, in which cellular material is injected into the patient to initiate the regenerative process. Cells obtained by reprogramming of the patient's own cells offer ethical and clinical advantages could provide a new source of material for therapeutic applications. Studies to date have shown that only a subset of differentiated cell types can be reprogrammed. Among these, keratinocytes, which are the most abundant proliferating cell type in the epidermis, have gained increasing attention as both donor and target cells for reprogramming and have become a new focus of regenerative medicine. As target cells for the treatment of skin defects, keratinocytes can be differentiated or reprogrammed from embryonic stem cells, induced pluripotent stem cells, fibroblasts, adipose tissue stem cells, and mesenchymal cells. As donor cells, keratinocytes can be reprogrammed or direct reprogrammed into a number of cell types, including induced pluripotent stem cells, neural cells, and Schwann cells. In this review, we discuss recent advances in keratinocyte reprogramming, focusing on the induction methods, potential molecular mechanisms, conversion efficiency, and safety for clinical applications. Graphical Abstract KCs as target cells can be reprogrammed or differentiated from fibroblasts, iPSCs, ATSCs, and mesenchymal cells. And as donor cells, KCs can be reprogrammed or directly reprogrammded into iPSCs, neural cells, Schwann cells, and epidermal stem cells.

Optogenetics has demonstrated great potential in the fields of tissue engineering and regenerative medicine, from basic research to clinical applications. Spatiotemporal encoding during individual development has been widely identified and is considered a novel strategy for regeneration. A as a noninvasive method with high spatiotemporal resolution, optogenetics are suitable for this strategy. In this review, we discuss roles of dynamic signal coding in cell physiology and embryonic development. Several optogenetic systems are introduced as ideal optogenetic tools, and their features are compared. In addition, potential applications of optogenetics for tissue engineering are discussed, including light-controlled genetic engineering and regulation of signaling pathways. Furthermore, we present how emerging biomaterials and photoelectric technologies have greatly promoted the clinical application of optogenetics and inspired new concepts for optically controlled therapies. Our summation of currently available data conclusively demonstrates that optogenetic tools are a promising method for elucidating and simulating developmental processes, thus providing vast prospects for tissue engineering and regenerative medicine applications.

In this paper, we investigate the formation control problems and the containment control problems for the multiple underactuated surface vessels. To deal with the coupling of unactuated and actuated states, we adopt a state transformation method to convert the nonlinear system into a linear one. We propose the expression of the leader vessels' formation controller and the followers' containment controller. Besides, two theorems are given to prove the stability of the closed loop system. Then, input transformation is used to get the actual controller for the system. Finally, we give a simulation example, and the results show the effectiveness of our theories.

Objective: Velocity vector imaging (VVI) allows noninvasive measurement of left ventricular (LV) strain and rotation angle-independently. We investigated strain, rotation and myocardial synchrony when pacing at different sites in the right ventricle to determine which site yields the most physiological pacing, as determined with VVI imaging. Method: Thirty-one patients with normal LV function referred for elective electrophysiology exam were used in this study. Catheters (6F quadripolar) were positioned in the right atrium, right ventricular apex, right ventricular outflow tract, and His bundle after electrophysiology exam was done. Regional and global LV circumferential strain (CS), radial strain (RS), and LV rotation of LV short-axis measurements were obtained. Two dyssynchrony parameters (AS-P delay and SDt6S) of CS and RS were obtained. Compare these values among each pacing, respectively. Result: CS, RS, and twist, which represent the LV systolic function, were significantly reduced in RVOT pacing and RVA pacing than RA pacing. Two dyssynchrony parameters (AS-P delay and SDt6S) were significantly longer in response to RVOT or RVA pacing compared to RA pacing. No significant differences were found between RVOT pacing and RVA pacing. CS and RS were obviously reduced in the regions surrounding the pacing site. There was no significant difference in CS, RS, twist, and mechanical dyssynchrony parameters when comparing His and RA pacing. Conclusion: Among these alternate right ventricular pacing locations, His bundle pacing is most like physiological pacing. Both RVOT pacing and RVA pacing worsen the normal LV systolic function with regard to strain, twist, and mechanical dyssynchrony along the LV short axis. (Echocardiography 2010;27:1219-1227)

Puerarin (4′-7-dihydroxy-8-β-d-glucosylisoflavone), the most abundant isoflavone-C-glucoside extracted from the root of the plant Pueraria lobata, has demonstrated anti-inflammatory activity in cellular models of inflammation. In this report, we examined the ability of puerarin to modulate C-reactive protein (CRP) expression and key molecules in the nuclear factor kappa B (NF-κB) pathway to determine its molecular target. The protein and mRNA levels of CRP were determined in lipopolysaccharide (LPS)-induced peripheral blood mononuclear cells of patients with unstable angina pectoris. Also, we detected the I-κBα phosphorylation and the p65NF-κB expression in peripheral blood mononuclear cells under our experimental condition. The results indicated that puerarin inhibited the expression of the protein and mRNA levels of CRP in LPS-induced peripheral blood mononuclear cells. Subsequently, we determined that the inhibition of CRP expression was because of a dose-dependent inhibition of phosphorylation and degradation of inhibitor kappaB(I-κB), which resulted in a reduction of p65NF-κB nuclear translocation. We conclude that puerarin acts as an anti-inflammatory agent by blocking NF-κB signalling, and may possibly be developed as a useful agent for the chemoprevention of atherosclerosis.

Background: The isoflavone puerarin is the most abundant isoflavone-C-glucoside extracted from the root (radix puerariae) of the plant Pueraria lobata and possesses many biological activities. In this report, the ability of puerarin to modulate intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1) and endothelial leukocyte adhesion molecule 1 (E-selectin), and to induce changes in the nuclear factor ĸB (NF-ĸB) pathway in human umbilical vein endothelial cells (HUVECs) was examined. Methods: The protein and mRNA levels of tumor-necrosis-factor-α (TNF-α)-induced ICAM-1, VCAM-1 and E-selectin were determined in HUVECs. Inhibitor ĸB (I-ĸB) phosphorylation and p65 NF-ĸB expression in HUVECs were also examined. Results: Puerarin inhibited the expression of TNF-α-induced ICAM-1, VCAM-1 and E-selectin proteins and mRNAs in HUVECs. Subsequently, we determined that the inhibition of ICAM-1, VCAM-1 and E-selectin expression was due to a dose-dependent suppression of phosphorylation and degradation of I-ĸB, which resulted in a reduction of p65 NF-ĸB nuclear translocation. Conclusion: These data suggested that the effect of puerarin-mediated inhibition of TNF-α-induced ICAM-1, VCAM-1 and E-selectin expression is attributed to suppressed NF-ĸB activation on the transcriptional level.

環境水の水質評価にとって重要な指標であるH＋濃度又はアルカリ度（OH−/HCO3−/CO32−等）を共存する1価陽イオン類の濃度（Na＋，NH4＋及びK＋）と共に陽イオン交換作用を用いる簡便な導電率検出イオンクロマトグラフィーを用いて同時分析するため，ドデシル硫酸リチウムを修飾したODS-シリカ分離カラムを用い，0.1 mMドデシル硫酸リチウムを含む40 mM塩化リチウムと0.05 mM硫酸の混合溶離液（pH 4.0）を用いる方法について検討した．その結果，1価陽イオン類及びH＋は，ドデシル硫酸基の有する陽イオン交換能により約15分以内で正のピークとして分離・検出できた．一方，アルカリ度は，酸・塩基中和反応による溶離液中のH＋濃度の減少として，H＋のピークの位置に負のピークとして検出できた．この最適分離条件下において，1価陽イオン類及びH＋/アルカリ度の検量線，検出限界，再現性及び添加回収率について検討し，良好な結果を得た．本法を種々な酸性又はアルカリ性の実際水試料に対して適用したところ，種々な実際水試料のH＋濃度及びアルカリ度の測定値は，本法と公定法の間で各々良好な相関性が認められた．このことから，本法の水質モニタリング法としての有用性が明らかとなった．

Influence of acidic eluent on retention behaviors of common anions and cations by ion-exclusion/cation-exchange chromatography (ion-exclusion/CEC) were investigated on a weakly acidic cation-exchange resin in the H(+)-form with conductivity. Sensitivities of analyte ions, especially weak acid anions (F(-) and HCOO(-)), were affected with degree of background conductivity level with pK(a1) (first dissociation constant) of acid in eluent. The retention behaviors of anions and cations were related to that of elution dip induced after eluting acid to separation column and injecting analyte sample. These results were largely dependent on the natures of acid as eluent. Through this study, succinic acid as the eluent was suitable for simultaneous separation of strong acid anions (SO(4)(2-), Cl(-), NO(3)(-) and I(-)), weak acid anions (F(-), HCOO(-) and CH(3)COO(-)), and cations (Na(+), K(+), NH(4)(+), Mg(2+) and Ca(2+)). The separation was achieved in 20 min under the optimum eluent condition, 20 mM succinic acid/2 mM 18-crown-6. Detection limits at S/N=3 ranged from 0.10 to 0.51 microM for strong acid anions, 0.20 to 5.04 microM for weak acid anions and 0.75 to 1.72 microM for cations. The relative standard deviations of peak areas in the repeated chromatographic runs (n=10) were in the range of 1.1-2.9% for anions and 1.8-4.5% for cations. This method was successfully applied to hot spring water containing strong acid anions, weak acid anions and cations, with satisfactory results.

The selective and simultaneous ion-exclusion chromatography (IEC) with UV-detection on a weakly acidic cation-exchange resin column in the H+ -form (TSKgel Super IC-A/C) was developed and applied for the simultaneous determination of phosphate and silicate ions as the water quality parameters required for optimizing the water-leaching process for ceramics glaze raw materials of natural origin including feldspar, woods-ash, and straw-ash. Phosphate and silicate ions in these water-leaching process water samples were separated selectively from the coexisting anions such as sulfate, chloride, nitrate and carbonate ions, based on the ion-exclusion separation mechanism. They were detected selectively and simultaneously by a postcolumn derivatization with molybdenum-yellow using the UV-detector. Under the optimized separation and detection conditions (eluent, 0-1 mM sulfuric acid; reactant, 10 mM sodium molybdate-25 mM sulfuric acid; detector, UV at 370 nm; temperature, 45 degrees C), the linearity of calibration was in the range 0.1 - 10 ppm for both phosphate and silicate ions, and the detection limits at S/N = 3 were 2.58 ppb for silicate ions and 4.75 ppb for phosphate ions. The effectiveness of this method was demonstrated in practical applications to the water-leaching process for some ceramics glaze raw materials.

An ion-exclusion chromatography method with ion-exchange enhancement of conductivity was developed for the selective separation and sensitive determination of hydrazine ion from alkali/alkaline earth metal cations and ammonium ion. Hydrazine ion was separated by ion-exclusion/penetration effect from other cations on a weakly basic anion-exchange column in the OH− form (TSKgel DEAE-5PW). Moreover, two different ion-exchange resin columns were inserted between the separating column and conductimetric detector in order to improve the sensitivity of hydrazine ion. The first enhancement column packed with a strongly basic anion-exchange resin in the SO42− form (TSKgel SAX) for hydrazine ion can convert from N2H5OH to (N2H5)2SO4. Moreover, the second enhancement column packed with a strongly acidic cation-change resin in the H+ form (TSKgel SCX) can convert to H2SO4. As a result, the sensitivity of hydrazine ion using two conductivity enhancement columns could be 26.8-times greater than using the separating column alone. This method was effectiveness also for the enhancement of ammonium ion (6.1-times) and sodium ion (1.2-times). The calibration graph of hydrazine ion detected as H2SO4 was linear over the concentration range of 0.001–100 ppm (r2=0.9988). The detection limit of hydrazine ion in this system was 0.64 ppb. Therefore, hydrazine ion in real boiler water sample could be accurately determined, avoiding the interference of other cations.

Vacancy ion-exclusion/adsorption chromatography has been applied to investigate the separation behavior of five aliphatic amines (ethylamine, propylamine, butylamine, pentylamine and hexylamine) on a polymethacrylate-based weakly basic anion-exchange column (Tosoh TSKgel DEAE-5PW). This system is consisted of analytes as a mobile phase and water as an injected sample. In the vacancy ion-exclusion/adsorption chromatography, the elution order was as follows: ethylaminepropylaminebutylaminepentylaminehexylamine, depending on their hydrophobicity. The retention times of the amines were decreased with decreasing their concentrations in the mobile phase. The retention times and resolutions of the amines were increased by adding a basic compound (e.g., lithium hydroxide or heptylamine) and by increasing the pH of mobile phase (pH11). This was because the dissociations of amine samples in the mobile phase were suppressed and thus the hydrophobic adsorption effects were enhanced. The linearity of calibration graphs could be obtained from the peak areas of the amine samples injected to the 0.05, 0.5 and 5 mM of amine mobile phase at pH 11 by heptylamine. The detection limits of aliphatic amines as injected samples were around 1 microM for five aliphatic amines at three different amine mobile phases. From these results, the retention behaviors of aliphatic amines on vacancy ion-exclusion/adsorption chromatography were concluded to be governed by the hydrophobic adsorption effect.

We introduced an approach to the ion chromatographic determination of common mono- and divalent cations including hydrogen ion and demonstrated the ability of a C30 column dynamically coated first with dodecylsulfate and then with 18-crown-6 ether to separate the cations by ion-exchange mechanism. Using an ethylenediamine solution containing a small concentration of 18-crown-6 ether and lithium dodecylsulfate at pH 6.2 as eluent, the cations were eluted in the order LiNa+NH4+H+K+Mg2+Ca2+ with symmetrical peaks. The conductivity vs. concentration plots were linear about three orders of magnitude, from millimolar to micromolar; and the detection limits were all0.6 microM. Rainwater was analyzed directly using this ion chromatographic system with satisfactory results.

This paper describes an ion-exclusion chromatographic system for the rapid and selective determination of ammonium ion. The optimized ion-exclusion chromatographic system was established with a polymethacrylate-based weakly basic anion-exchange resin column (TSKgel DEAE-5PW) as the separation column, an aqueous solution containing 0.05 mM tetramethylammonium hydroxide (pH 9.10) as eluent with conductimetric detection for the analyte determination. Under the optimum chromatographic conditions, ammonium ion was determined within 2.3 min with a detection limit (S/N=3) better than 0.125 microM. Ammonium ion in rain and river waters was precisely determined using this ion-exclusion chromatographic system.

A new and simple approach is described for the determination of the haloacetic acids (such as mono-, di- and trichloroacetic acids) usually found in drinking water as chlorination by-products after disinfection processes and acetic acid. The new approach, termed vacancy ion-exclusion chromatography, is based on an ion-exclusion mechanism but using the sample solution as the mobile phase, pure water as the injected sample, and a weakly acidic cation-exchange resin column (TSKgel OApak-A) as the stationary phase. The addition of sulfuric acid to the mobile phase results in highly sensitive conductivity detection with sharp and well-shaped peaks, leading to excellent and efficient separations. The elution order was sulfuric acid, dichloroacetic acid, monochloroacetic acid, trichloroacetic acid, and acetic acid. The separation of these acids depends on their pKa values. Acids with lower pKa values were eluted earlier than those with higher pKa, except for trichloroacetic acid due to a hydrophobic-adsorption effect occurring as a side-effect of vacancy ion-exclusion chromatography. The detection limits of these acids in the present study with conductivity detection were 3.4 microM for monochloroacetic acid, 0.86 microM for dichloroacetic acid and 0.15 microM for trichloroacetic acid.

In this study, an aqueous solution consisting of benzoic acid with low background conductivity and beta-cyclodextrin (beta-CD) of hydrophilic nature and the inclusion effect to benzoic acid were used as eluent for the ion-exclusion chromatographic separation of aliphatic carboxylic acids with different pKa values and hydrophobicity on a polymethacrylate-based weakly acidic cation-exchange resin in the H+ form. With increasing concentration of beta-cyclodextrin in the eluent, the retention times of the carboxylic acids decreased due to the increased hydrophilicity of the polymethacrylate-based cation-exchange resin surface from the adsorption of OH groups of beta-cyclodextrin. Moreover, the eluent background conductivity decreased with increasing concentration of beta-cyclodextrin in 1 mM benzoic acid, which could result in higher sensitivity for conductimetric detection. The ion-exclusion chromatographic separation of carboxylic acids with high resolution and sensitivity was accomplished successfully by elution with a 1 mM benzoic acid-10 mM cyclodextrin solution without chemical suppression.

A monolithic ODS-silica gel column modified by saturating it with lithium dodecylsulfate (Li-DS) was used to demonstrate the high-speed separation of H+ from other mono- and divalent cations, such as Na+, NH4+, K+, Mg2+ and Ca2+ using ion chromatography (IC). Using a 5 mM EDTA-2K solution containing 0.10 mM Li-DS (pH 4.80) as eluent, H+ was eluted with a sharp and symmetrical peak within 1.0 min before other cations at a flow-rate of 1.5 ml min(-1). The rapid elution of H+ and its conductimetric detection could be attributed to the presence of EDTA (HY2-), which can convert H+ ions as anions. i.e. H(+) + H2Y(2-) --> H3Y(-). The acidity of rainwater and deionized water samples was determined using this IC system with satisfactory results.

陶磁器ゆう薬原料の品質管理を目的に，代表的な天然ゆう薬原料（釜戸長石，福島長石，平津長石，大和長石，大平長石及び木灰）中に含まれる種々な陰イオン（硫酸，塩化物及び硝酸イオン）及び陽イオン（ナトリウム，アンモニウム，カリウム，マグネシウム及びカルシウムイオン）の同時分離定量を可能にする導電率検出イオン排除/陽イオン交換型イオンクロマトグラフィーについて検討した．その結果，1本の分離カラム（ポリメタクリレートをマトリックスとする弱酸性陽イオン交換樹脂）と1種類の溶離液（7 mM酒石酸/3.5 mM 18-クラウン-6）を用いるイオン排除/陽イオン交換型イオンクロマトグラフィーにより，イオン排除による陰イオンの分離と陽イオン交換による陽イオンの分離が約7分以内で同時かつ選択的に達成できた．一方，本法による導電率検出器応答は，陰イオンに関して正，陽イオンに関して負であり，選択的な検出が可能であった．本法は，種々な陶磁器ゆう薬原料の水抽出液中に含まれる種々な陰及び陽イオンの選択的同時分離定量に対して良好に応用でき，その有用性が明らかとなった．

A monolithic ODS-silica gel column modified by saturating it with lithium dodecylsulfate (Li-DS) was firstly used to separate monovalent cations simultaneously including H+, Na+, NH4+ and K+ by ion-chromatography (IC). Using an acidified 60 mM LiCl solution (pH 3.95, containing 0.10 mM Li-DS) as eluent, these monovalent cations were separated well in the order of Na+

A carboxybetaine-type zwitterionic stationary phase obtained by immobilizing Mitsubishi Reagent EF-700 (C8F17SO2NHC3H6N+ (CH3)2-C2H4-COO–) onto a reversed-phase column was used for chromatographic separation of ions. When aqueous electrolyte solutions having higher pH values (>8) were used as eluents, the model analyte ions (NO2 –, H2PO4 –, Cl–, Br–, NO3 –, ClO3 –, I– and SCN–) were co-eluted and appeared at the void volume of this HPLC system. However, when aqueous electrolyte solutions having lower pH values (

A new approach to ion-exclusion chromatography (IEC) is proposed to overcome the relatively poor conductivity detection response which occurs in IEC on when acids are added to the eluent in order to improve peak shape. This approach, termed vacancy IEC, requires the sample to be used as mobile phase and a sample of water to be injected onto a polystyrene/divinylbenzene (PS/DVB)-based strongly acidic cation-exchange column (TSKgel SCX). Vacancy peaks for each of the analytes appear at the retention times of these analytes. Highly sensitive conductivity detection is possible and sharp, well-shaped peaks are produced, leading to efficient separations. Retention times were found to be affected by the concentration of the analytes in the eluent, and also by the presence of an organic modifier, such as butanol in the mobile phase. Detection limits for oxalic, formic, acetic, propionic, butyric and valeric acids at S/N=3 were 0.04, 0.1, 0.47, 0.66, 0.71 and 0.82 μM, respectively, and linear ranges for some acids extended over two-orders of magnitude. Precision values for retention times were

With conventional capillary electrophoresis (CE), it was difficult to directly analyze samples containing proteins as a result of the irreversible adsorption of proteins onto the inner surface of the capillary column. This difficulty, however, was completely overcome by adding N-dodecylphosphocholine (DPC, a phosphobetaine-type zwitterionic surfactant) to the background electrolyte (BGE). DPC made two essential contributions to the determination of common inorganic cations in the protein-containing samples: protein adsorption onto the capillary walls was completely avoided, and the resolution of the analyte cations was essentially improved. The optimal BGE for analysis of biological samples was found to be 5 mM DPC, 5 mM copper(II) acetate/10 mM ethylenediamine (pH 8). The detection limits (signal-to-noise ratio =3 and UV at 215 nm) of sodium, potassium, calcium, magnesium, and ammonium ions were 25, 31, 24, 45, and 60 micro M, respectively. These five species of the common inorganic cations in human saliva samples were detected successfully within 2 min by the proposed system with direct sample injection.

Weakly acidic cation exchange resin can be used for simultaneous separation of anions and cations when acidic eluents were employed. On the weakly acidic cation exchange resin, anions were retained by ion exclusion mechanism, while cations by cation exchange mechanism. The selection of eluent is very important for the separation of interesting analytes. In this study, a mixture of 0.6 mmol/L 2,6-pyridinedicarboxylic acid (PDCA), 0.75 mmol/L sulfosalicylic acid (SSA), and 6.0 mmol/L 18-crown-6 was employed as eluent for the simultaneous separation of common inorganic anions (Cl−, NO3 − and SO4 2−) and cations (Na+, NH4 +, K+, Mg2+, and Ca2+). A good separation of these anions and cations on the weakly acidic cation exchange column (Tosoh TSKgel OApak-A) was achieved in 16 min. The linear range of peak area calibration curves for all analytes were up to two orders of magnitude. The conductivity detection limits calculated at S/N=3 were from 0.2 to 1.6 μmol/L for anions and cations. The method developed in t...

A new ion chromatographic (IC) system, in which n-tetradecylphosphocholine (TDPC, a phosphobetaine type of zwitterionic surfactant) was used as the stationary phase, pure water as the mobile phase, and conductivity as the method of detection, has been developed for the determination of inorganic acids. Five model acids, HCl, HNO3, HClO4, H2SO4, and H3PO4, were separated to baseline and eluted in the order H3PO4 > HCl > HNO3 > H2SO4 > HClO4. When peak areas were plotted against the concentrations of the acids in samples, linear calibration curves were obtained. Ultimate determination limits were approximately 1 mmol L–1, but the discrimination of the method between solutions of different concentration was better than 10 μmol L–1 for those model analytes. Salts of divalent cations could also be separated, but they were eluted faster than the acids. No separation was observed for the salts of monovalent cations. This newly proposed approach is applicable to the simultaneous determination of the inorganic acids (produced by reactions of NOx, SOx, and HCl with water) in aerosols.

This paper describes an electrostatic ion chromatographic system in which the separation selectivity for inorganic anions, especially for sulfate and phosphate, could be manipulated by altering the molar ratio of the zwitterionic and cationic surfactants in the column coating solution used to prepare the stationary phase. The zwitterionic surfactant used for this study was 3-(N,N-dimethyltetradecylammonio)propanesulfonate (Zwittergent-3-14) and the cationic surfactant was tetradecyltrimethylammonium (TTA). Using a reversed-phase C18 column (250x4.6 mm I.D.) coated with 10/10 (mM/mM) of TTA/Zwittergent-3-14 mixed micelles as the stationary phase and either NaHCO3 or Na2CO3 aqueous solution as the eluent, together with suppressed conductivity detection, baseline separation of seven model inorganic anions was obtained. The elution order for those anions was found to be F+HPO4(2-)Cl-SO4(2-)NO2-Br-NO3-. Under the same conditions but using 1/10 (mM/mM) of TTA/Zwittergent-3-14 mixed micelles as the column coating solution, the elution order for these model ions was F-HPO4(2-)SO4(2-)Cl-NO2-Br-NO3-. The early elution of phosphate and sulfate is a unique attribute of this system. Detection limits for F-, HPO4(2-), Cl-, SO4(2-), NO2-, Br- and NO3- (S/N=3, sample injection volume 100 microl) were 0.11, 0.12, 0.12, 0.18, 0.49, 0.49, 0.52 microM, respectively.

An ion chromatographic (IC) method has been developed for determination of hydrogen ion (H+). It is based on the use of sulfonated cation-exchange resin as stationary phase, aqueous ethylenediamine-N,N,N′,N′-tetraacetic acid (dipotassium salt, EDTA-2K, written as K2H2Y) solution as mobile phase, and conductivity for detection. H+ was separated mainly by cation-exchange, but its elution was accelerated by the presence of EDTA. The order of elution for the model cations was H+ > Li+ > Na+ > NH4+ > Ca2+ > > Mg2+. A sharp and highly symmetrical peak was obtained for H+ and this was attributed to the capacity of H2Y22– to receive and bind H+. H+ was detected conductiometrically and detector response (reduction in conductivity as a result of H++H2Y2–→H3Y–) was linearly proportional to the concentration of H+ in the sample. The detection limit for H+ with this IC system was better than 4.7 μmol L–1. A significant advantage of this method was the ability to separate and determine, in one step, H+ and other cations. The successful determination of H+ and other cation species in real acid-rain samples demonstrated the usefulness of this method.