Smart Target-Initiated Catalytic DNA Junction Circuit Amplification Strategy for the Ultrasensitive Electrochemiluminescence Detection of MicroRNA.

One of the highly attractive research directions in the electrochemiluminescence (ECL) field is how to regulate and improve ECL efficiency. Quantum dots (QDs) are highly promising ECL materials due to their adjustable luminescence size and strong luminous efficiency. MoS2 NSs@QDs, an ECL emitter, is synthesized via hydrothermal methods, and its ECL mechanism is investigated using cyclic voltammetry and ECL-potential curves. Then, a stable and vertical attachment of a triplex DNA (tsDNA) probe to the MoS2 nanosheets (NSs) is applied to the electrode. Next, an innovative ECL sensor is courageously empoldered for precise and ultrasensitive detection of target miRNA-199a through the agency of ECL-resonance energy transfer (RET) strategy and a dextrous target-initiated catalytic three-arm DNA junction assembly (CTDJA) based on a toehold strand displacement reaction (TSDR) signal amplification approach. Impressively, the ingenious system not only precisely regulates the distance between energy donor-acceptor pairs leave energy less loss and more ECL-RET efficiency, but also simplifies the operational procedure and verifies the feasibility of this self-assembly process without human intervention. This study can expand MoS2 NSs@QDs utilization in ECL biosensing applications, and the proposed nucleic acid amplification strategy can become a miracle cure for ultrasensitive detecting diverse biomarkers, which helps researchers to better study the tumor mechanism, thereby unambiguously increasing cancer cure rates and reducing the risk of recurrence.

A water-soluble fluorescent probe for detecting creatinine in totally aqueous media and imaging exogenous creatinine in living cells.

The design of vigorous tools for creatinine determination is extremely important in the diagnosis and treatment of kidney diseases. In the study, we examine a robust fluorescent turn-on probe (NCP-Pd) for creatinine detection in a completely aqueous solution based on the metal palladium-catalyzed reaction. In the presence of creatinine, the NCP-Pd dissociates and subsequently restores the fluorescence due to elimination of the heavy atom quenching effect and prevention of the photoinduced electron transfer effect. The probe NCP-Pd displays excellent detecting performance with respect to creatinine such as good water solubility, high selectivity, and a low detection limit (0.16 µM). Additionally, in order to ensure its clinical application, this probe is operated in blood serum samples for detecting creatinine and compared with a commercial clinical method. The results indicate an extremely high agreement with the commercial clinical method. Furthermore, the results confirm that the probe NCP-Pd exhibits satisfactory cell permeability and low cytotoxicity and can detect creatinine in L929 and HCT116 cells. The study provides a potential application for detecting creatinine and conducting pathological research on creatinine-involved diseases.

CRISPR/Cas12a-triggered ordered concatemeric DNA probes signal-on/off multifunctional analytical sensing system for ultrasensitive detection of thalassemia.

Based on CRISPR/Cas12a triggered ordered concatemeric DNA probes, a "on/off" self-powered biosensor is developed to achieve highly sensitive detection of thalassemia gene CD142 through open-circuit potential-assisted visual signal output. The ingeniously constructed glucose oxidase (GOD)-functionalized ordered concatemeric DNA probe structure can significantly amplify signal output, while the coupled CRISPR/Cas12a system is served as a "signal switch" with excellent signal-transducing capabilities. When the ordered concatemeric DNA probe structure is anchored on electrode, the response signal of the sensing system is in the "signal on" mode. While, the presence of the target activates the non-specific cleavage activity of the CRISPR/Cas12a system, causing the sensing system to switch to the "signal off" mode. In the detection system, GOD catalyzes the oxidation of glucose to produce hydrogen peroxide, which further catalyzes the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to form a color product, enabling visual signal of the target through naked-eye color contrast. By employing a multifunctional analytical mode combining electrochemical and visual signal outputs, accurate determination of the target is achieved, with linear ranges of 0.0001-100 pM, and detection limits of 48.1 aM (S/N = 3). This work provides a reference method for sensitive detection of thalassemia genes and holds great diagnostic potential in biomedical applications.

Magnetodielectric Properties of Ordered Microstructured Polydimethylsiloxane-Based Magnetorheological Elastomer with Fe3O4@rGO Nanoparticles.

Magnetodielectric properties of prepared ordered microstructured polydimethylsiloxane-based magnetorheological elastomer with the Fe3O4@rGO (Fe3O4@rGO/PDMS-MRE) were investigated to expand the application of magnetorheological elastomer (MRE) in magnetic sensing fields by improving the magnetodielectric effect. Five types of Fe3O4@rGO electromagnetic biphasic composite particles were synthesized by the solvothermal method, and their characterization and magnetic properties were also tested. Microstructurally ordered Fe3O4@rGO/PDMS-MRE samples with different Fe3O4@rGO concentrations were obtained through the magnetic field orientation technique, an experimental platform for magnetodielectric properties was built, and the relative permittivity of the samples was tested under magnetic flux density from 0 to 500 mT. The results show when the ratio of modified Fe3O4 to GO reaches 10:1, the Fe3O4@rGO composite particles exhibit uniform distribution with a flaky structure and strong magnetic properties and have the best bonding effect of composite particles. The relative permittivity of Fe3O4@rGO/PDMS-MRE increases with the rise of Fe3O4@rGO concentration and applied magnetic flux density. The relative permittivity of Fe3O4@rGO/PDMS-MRE with Fe3O4@rGO concentration of 60 wt% reaches 12.934 under the action of 500 mT magnetic flux density, and the magnetodielectric effect is as high as 92.4%. A reasonable mechanism for improving the magnetodielectric effect of ordered microstructured Fe3O4@rGO/PDMS-MRE is proposed.

Modeling molecular acidity with electronic properties and Hammett constants for substituted benzoic acids.

Molecular acidity is an important physiochemical property essential in many fields of molecular studies, but an efficient and reliable computational approach to make accurate predictions is still missing. In this work, based on our previous studies to use gas phase electronic properties such as molecular electrostatic potential and valence natural atomic orbitals of the acidic atom and leaving proton, we demonstrate here that different approaches can be employed to tackle this problem. To that end, we employ 196 singly, doubly, and triply substituted benzoic acids for the study. We show that two different approaches are possible, one focusing on the carboxyl group through its localized electronic properties and the other on the substituting groups via Hammett constants and their additivity rule. Our present results clearly exhibit that with the linear models built from the singly substituted species, one can accurately predict the pK(a) values for the doubly and triply substituted species with both of these two approaches. The predictions from these approaches are consistent with each other and agree well with the experimental data. These intrinsically different approaches are the two manifestations of the same molecular acidity property, both valid and complementary to each other.

Effect of ferric and bromide ions on the formation and speciation of disinfection byproducts during chlorination.

The effects of ferric ion, pH, and bromide on the formation and distribution of disinfection byproducts (DBPs) during chlorination were studied. Two raw water samples from Huangpu River and Yangtze River, two typical drinking water sources of Shanghai, were used for the investigation. Compared with the samples from Huangpu River, the raw water samples from Yangtze River had lower content of total organic carbon (TOC) and ferric ions, but higher bromide concentrations. Under controlled chlorination conditions, four trihalomethanes (THMs), nine haloacetic acids (HAAs), total organic halogen (TOX) and its halogen species fractions, including total organic chlorine (TOC1) and total organic bromide (TOBr), were determined. The results showed that co-existent ferric and bromide ions significantly promoted the formation of total THMs and HAAs for both raw water samples. Higher concentration of bromide ions significantly changed the speciation of the formed THMs and HAAs. There was an obvious shift to brominated species, which might result in a more adverse influence on the safety of drinking water. The results also indicated that high levels of bromide ions in raw water samples produced higher percentages of unknown TOBr.

Seasonal variation effects on the formation of trihalomethane during chlorination of water from Yangtze River and associated cancer risk assessment.

For the system of water samples collected from Yangtze River, the effects of seasonal variation and Fe(III) concentrations on the formation and distribution of trihalomethanes (THMs) during chlorination have been investigated. The corresponding lifetime cancer risk of the formed THMs to human beings was estimated using the parameters and procedure issued by the US EPA. The results indicated that the average concentration of THMs (100.81 microg/L) in spring was significantly higher than that in other seasons, which was related to the higher bromide ion concentration resulted from the intrusion of tidal saltwater. The total cancer risk in spring reached 8.23 x 10(-5) and 8.86 x 10(-5) for males and females, respectively, which were about two times of those in summer under the experimental conditions. Furthermore, it was found that the presence of Fe(III) resulted in the increased level of THMs and greater cancer risk from exposure to humans. Under weak basic conditions, about 10% of the increment of THMs from the water samples in spring was found in the presence of 0.5 mg/L Fe(III) compared with the situation without Fe(III). More attention should be given to the effect of the coexistence of Fe(III) and bromide ions on the risk assessment of human intake of THMs from drinking water should be paid more attention, especially in the coastland and estuaries.

A Review of Piezoelectric Vibration Energy Harvesting with Magnetic Coupling Based on Different Structural Characteristics.

Piezoelectric vibration energy harvesting technologies have attracted a lot of attention in recent decades, and the harvesters have been applied successfully in various fields, such as buildings, biomechanical and human motions. One important challenge is that the narrow frequency bandwidth of linear energy harvesting is inadequate to adapt the ambient vibrations, which are often random and broadband. Therefore, researchers have concentrated on developing efficient energy harvesters to realize broadband energy harvesting and improve energy-harvesting efficiency. Particularly, among these approaches, different types of energy harvesters adopting magnetic force have been designed with nonlinear characteristics for effective energy harvesting. This paper aims to review the main piezoelectric vibration energy harvesting technologies with magnetic coupling, and determine the potential benefits of magnetic force on energy-harvesting techniques. They are classified into five categories according to their different structural characteristics: monostable, bistable, multistable, magnetic plucking, and hybrid piezoelectric-electromagnetic energy harvesters. The operating principles and representative designs of each type are provided. Finally, a summary of practical applications is also shown. This review contributes to the widespread understanding of the role of magnetic force on piezoelectric vibration energy harvesting. It also provides a meaningful perspective on designing piezoelectric harvesters for improving energy-harvesting efficiency.

Folic acid modified TPGS as a novel nano-micelle for delivery of nitidine chloride to improve apoptosis induction in Huh7 human hepatocellular carcinoma.

BACKGROUND: The development of novel and effective drugs for targeted human hepatocellular carcinoma still remains a great challenge. The alkaloid nitidine chloride (NC), a component of a traditional Chinese medicine, has been shown to have anticancer properties, but doses at therapeutic levels have unacceptable side effects. Here we investigate folic acid modified D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS-FA) as a potential carrier for controlled delivery of the drug. METHODS: Synthesized TPGS-FA was characterized by FTIR, UV-visible and 1H NMR spectroscopy, and TPGS loaded with NC was evaluated for its ability to induce apoptosis in Huh7 cells by Annexin V/PI and MTT assays, and observed by laser scanning confocal microscopy and inverted phase contrast microscopy. RESULTS: TPGS-FA/NC complexes were prepared successfully, and were homogenious with a uniform size of ~ 14 nm diameter. NC was released from the TPGS-FA/NC complexes in a controlled and sustained manner under physiological conditions (pH 7.4). Furthermore, its cytotoxicity to hepatocarcinoma cells was greater than that of free NC. CONCLUSIONS: TPGS-FA is shown to be useful carrier for drugs such as NC, and TPGS-FA/NC could potentially be a potent and safe drug for the treatment of hepatocellular carcinoma.

Adverse Psychological Reactions and Psychological Aids for Medical Staff During the COVID-19 Outbreak in China.

Background: The outbreak of the novel coronavirus disease COVID-19 caused panic and psychological stress throughout the World. We investigated the extent of adverse psychological reactions in two medical staff groups in China, and explored the importance of online psychological assistance for them. Methods: A cross-sectional online survey including Hospital Anxiety and Depression Scale (HADS) and Insomnia Severity Index (ISI) was utilized to assess anxiety, depression, and insomnia. Propensity score matching (PSM) was applied to match sex and age between the two groups. Differences in the prevalence of adverse psychological reactions between the two groups were compared by a Chi-square test. A multivariate logistic regression analysis was utilized to search for associated adverse psychological reaction factors of two groups. Results: A total of 2,920 medical staff took part in the survey, including 470 frontline and 2,450 non-frontline medical staff. The risk of the frontline group experiencing anxiety, depression, insomnia-early, insomnia-middle, and insomnia-late were 1.16, 1.28, 1.26, 1.22, 1.28 times those of the non-frontline group after PSM. For frontline medical staff, the spinsterhood state (OR = 1.23, 95% CI: 1.00-1.51; P = 0.05) was a risk factor for anxiety. Bachelor or college degree (OR = 2.23, 95% CI: 1.24-4.02, P = 0.01) and a contact history with COVID-19 patients (OR = 1.62, 95% CI: 1.10-2.40; P = 0.02) were risk factors for insomnia. For non-frontline medical staff, being a woman (OR = 1.49, 95% CI: 1.08-2.06, P = 0.01) was a risk factor for anxiety, whilst being in a middle age group was a protective factor for anxiety (OR = 0.70, 95% CI: 0.50-0.99, P = 0.04) and depression (OR = 0.65, 95% CI: 0.45-0.93, P = 0.02). Being a woman (OR = 1.47, 95% CI: 1.14-1.89, P = 0.003) and working in a COVID-19 unit (OR = 1.31, 95% CI: 1.11-1.54, P = 0.001) were risk factors for insomnia, whilst the spinsterhood state (OR = 0.80, 95% CI: 0.67-0.95; P = 0.01) was a protective factor for insomnia. Online forms of psychological aid were all popular with medical staff. Conclusions: The prevalence of anxiety, depression, and insomnia in frontline medical staff was significantly higher than in the non-frontline group. Appropriate intervention methods should be adopted according to the different influencing factors of the two groups. Online psychological aid was the preferred mechanism for relieving psychological problems.

Characterization of dissolved organic matter derived from atmospheric dry deposition and its DBP formation.

Disinfection by-products (DBPs) precursors can be regarded mainly from the drinking water sources and the water treatment processes. A recent study showed that dissolved organic matter (DOM) in atmosphere is an important precursor source of DBPs through atmospheric wet deposition. However, little information is available on the characteristics of DOM derived from dry deposition particulate matter (PM) and the impact of dry deposition on CX3R-type DBP formation. This study determined whether dry deposition directly contributed the production of DBPs during chlor (am)ination and investigated the mechanism behind the contribution based on the combination of the resin and membrane for fractionating DOM fractions. The results showed that the hydrophilic fraction (HPI) contributed the most DOM and low molecular weight DOM (<10 kDa) was the main component of HPI. In addition, aromatic proteins and soluble microbial products-like compounds were the dominant fluorescent species in DOM derived from PM, and <10 kDa transphilic was the most abundant. The concentrations of C-DBPs and N-DBPs in disinfected PM solution were trihalomethanes (THMs) > haloacetic acids (HAAs) > haloaldehydes and haloacetamides > haloacetonitriles > halonitromethanes for both chlorination and chloramination. The main contributors of calculated toxicity are transphilic and hydrophobic in chlorination and chloramination respectively. Dry deposition PM was deduced to contribute DOM and DBP formation after chlorination in surface water, especially THMs and HAAs. These results presented herein provide key information for controlling DBPs from the perspectives of atmospheric dry deposition, especially in the case of heavy air pollution.

Accelerated oxidation of iopamidol by ozone/peroxymonosulfate (O3/PMS) process: Kinetics, mechanism, and simultaneous reduction of iodinated disinfection by-product formation potential.

Iopamidol (IPM) is a potential source of toxic iodinated byproducts (I-DBPs) during water disinfection. In this work, we determined the kinetics and mechanism of degradation of IPM by a combination of ozone (O3) and peroxymonosulfate (PMS, HSO5-), and assessed its effect on the formation of iodinated trihalomethanes (I-THMs) during chlorination treatment. The degradation of IPM was accelerated by the O3/PMS process, and the hydroxyl (HO•) and sulfate (SO4•-) radicals were major contributors to the degradation. Using identification of the second order reaction rate between SO4•- and IPM (kSO4•-, IPM = 1.6 × 109 M-1 s-1), the contribution of HO• to the degradation was determined to be 78.3%. The degradation of IPM was facilitated by pH > 7, and natural organic matter (NOM) and alkalinity had limited effects on the degradation of IPM in the O3/PMS process. The transformation products of IPM were determined and inferred by QTOF-MS/MS, and the degradation pathways were elucidated. These include amide hydrolysis, amino oxidation, hydrogen abstraction, deiodination, and hydroxyl radical addition. Interestingly, oxidation of IPM by O3/PMS also decreased its potential for formation of I-THMs. After oxidation of IPM, the I-THMs formed from 5-µΜ IPM decreased from 14.7 µg L-1 to 3.3 µg L-1 during chlorination. Although the presence of NOM provided the precursor of I-THMs during chlorination of IPM, the O3/PMS process decreased I-THMs formation by 71%, because oxidation of released iodide into iodate effectively inhibited I-THMs formation. This study provides a new approach for the accelerated degradation of IPM and control of the formation of I-DBPs.

Kinetic and mechanistic insights into the abatement of clofibric acid by integrated UV/ozone/peroxydisulfate process: A modeling and theoretical study.

The feasibility of integrated UV/ozone (O3)/peroxydisulfate (PDS) process for abatement of clofibric acid (CA) was systematically explored in this study with focus on the kinetic simulation and oxidation mechanisms. The results indicated the UV/O3/PDS process was of prominent treatment capability with pseudo-first-order rate constant of CA degradation increased by 65.9% and 86.0% compared to UV/O3 and UV/PDS processes, respectively. A chemical kinetic model was developed and successfully employed to predict CA elimination as well as the specific contributions of UV, hydroxyl radical (•OH) and sulfate radical (SO4•-) under different PDS dosage, pH, natural organic matters, bicarbonate and chloride conditions in UV/O3/PDS process. According to quantum chemical calculation, radical addition on ortho site of isopropoxy substituent and single electron transfer were corroborated to be the dominant reaction channels for the oxidation of CA by •OH and SO4•-, respectively. Additionally, the reactive sites and transformation pathways of CA were proposed via Fukui function calculation and UPLC-Q-TOF-MS analysis. Moreover, the performance of UV/O3/PDS process was further evaluated with regard to the energy demand and bromate formation. This study first proposed a kinetic model in UV/O3/PDS process and elucidated the regioselectivity and products distribution of CA during oxidative treatment.

Has the formation of disinfection by-products been overestimated? Membrane leakage from syringe filter heads serves as unexpected precursors.

Syringe filters are widely used for sample pretreatments in laboratories. This study found that, surprisingly, these filters can leak dissolved organic carbon (DOC) that can potentially serve as precursors of disinfection by-products (DBPs). Nine common types of syringe filters were assessed. The results showed that the DOC of ultrapure water increased after syringe filtration. The DOC shed from filter membranes was characterized, whose spectra showed that the main compounds exhibited a low apparent molecular weight. Five classes of DBPs were investigated including trihalomethanes, haloacetaldehydes, haloacetonitriles, haloacetamides and halonitromethanes, among which trichloromethane (TCM), dichloroacetaldehyde (DCAL), trichloroacetaldehyde (TCAL), dichloroacetonitrile (DCAN), and trichloronitromethane (TCNM) were principally detected. The DBP formation was affected by chlorination time and membrane types. In general, the use of the poly vinylidene fluoride membrane resulted in the highest formation of TCM and TCAL, whereas nylon and mixed cellulose esters membranes contributed significantly to the formation of DCAN and TCNM, respectively. The shedding DOC and the formation of TCM, DCAL and TCAL from filter membranes were mitigated effectively by pre-washing; however, the contribution of membrane leakage to DCAN and TCNM formation was still notable, even with a pre-wash volume of 50 mL. When unwashed syringe filters were used for a real water sample, the DBP formation increased by up to 73.2% compared to the pre-washed ones; particularly for TCNM it was always over 15%. Therefore, for better quality control in laboratories, more attention should be paid to the syringe filters during sample pre-treatments, particularly when DBP formation is being investigated.

An AIE fluorescent probe with a naphthalimide derivative and its application for detection of hypochlorite and imaging inside living cells.

Hypochlorite (ClO-) is a highly reactive oxygen species that plays an important role in resistance to attacks by microorganisms. Herein, we report the preparation of a fluorescence probe (NIB-M) through the integration of a naphthalimide moiety and ClO- to capture diaminomaleonitrile and employ it for the aggregation-induced emission-based (AIE-based) monitoring of ClO-. In the presence of ClO-, NIB-M undergoes sequential nucleophilic substitution and HCl elimination reactions that allow it to possess high selectivity, a fast response, and a low detection limit (0.032 µM). Due to the good AIE properties of the parent molecule, a ClO- test board was facilely prepared by loading NIB-M on a Whatman paper strip-based portable device. The test plate can conveniently and sensitively detect hypochlorite onsite. In addition, the NIB-M probe was used for the imaging of exogenous/endogenous ClO- inside living cells.

Efficient degradation of organic pollutants by low-level Co2+ catalyzed homogeneous activation of peroxymonosulfate.

Dissolved cobalt ions (Co2+) are an excellent catalyst for activating peroxymonosulfate (PMS) to generate SO4- for the degradation of organic pollutants, but fairly high level of Co2+ is generally required, which may cause secondary pollution due to its toxicity. Herein, we demonstrate a novel strategy for this catalytic oxidation treatment in which the required Co2+ addition is very small, being much less than the emission limit of 17 µmol L-1. This new strategy is based on the much enhanced catalytic effect by the addition of small organic acids (SOAs). In a typical case, all the added diclofenac (30 µmol L-1) was degraded in 20 min by using 2 µmol L-1 Co2+, 0.15 mmol L-1 PMS and 0.5 mmol L-1 acetate with a degradation rate constant of 0.482 min-1, which was about 10 times higher than that (0.048 min-1) of equivalent Co2+-PMS system without acetate. The formation of SO4- was greatly enhanced by introducing acetate, and this novel system is universal for enhanced degradation of various organic pollutants. Similarly, formate, propionate, and butyrate also exhibited enhancing effects on the catalytic ability of Co2+. The enhancement mechanism of SOAs on catalytic activation of PMS by low-level Co2+ was also proposed.

Kinetic and mechanistic aspects of selenite oxidation by chlorine, bromine, monochloramine, ozone, permanganate, and hydrogen peroxide.

Selenium (mainly in the forms of selenite (Se(IV)) and selenate (Se(VI)) is a regulated drinking water contaminant, but there is little information on the kinetics and mechanisms of Se(IV) oxidation during water treatment. Species-specific and apparent second-order rate constants for the oxidation of Se(IV) at pH 7.0 were determined in buffered solutions and they decrease in the order bromine (5.8 ±â€¯0.3 × 103 M-1 s-1) > ozone (O3, 513.4 ±â€¯10.0 M-1 s-1) > chlorine (61.0 ±â€¯3.6 M-1 s-1) > permanganate (2.1 ±â€¯0.1 M-1 s-1), monochloramine (NH2Cl, (1.3 ±â€¯0.1) × 10-3 M-1 s-1), and hydrogen peroxide (H2O2, (2.3 ±â€¯0.1) × 10-5 M-1 s-1). The reaction stoichiometries for the reactions of Se(IV) with bromine, O3, chlorine, NH2Cl, and H2O2 are 1:1. For Mn(VII), the stoichiometries varied with pH and were 5:2, 3:2, and 1:2 for acidic, neutral, and alkaline conditions, respectively. Based on the reaction orders and stoichiometries, the corresponding Se(IV) oxidation mechanisms for various oxidants are discussed. The role of bromide for Se(IV) oxidation was also investigated during chlorination and ozonation of Se(IV)-containing water. During chlorination, bromide-catalysis enhances the rate of the oxidation of Se(IV) to Se(VI) from 50% to nearly 90% with bromide concentrations of 50 µg L-1 and 200 µg L-1, respectively, at pH 7.0 and a chlorine dose of 2.0 mg L-1 (within 15 min). During ozonation, bromide had no effect on Se(IV) oxidation. Based on the determined second order rate constants, the oxidation of Se(IV) by chlorine and ozone were successfully predicted in a natural water by a kinetic model. The second order rate constants for the same oxidants were also investigated and/or evaluated for other related anions, such as arsenite (As(III)) and sulfite (S(IV)). They decreased in the order S(IV) > As(III) > Se(IV).

Mechanisms of Adsorption of Heavy Metal Cations from Waters by an Amino Bio-Based Resin Derived from Rosin.

Rosin derived from conifer trees is used as the basis for a novel environmentally-friendly adsorbent prepared from a sustainable resource. After treatment with ethylenediamine, ethylenediamine rosin-based resin (EDAR) is produced, which possesses cation exchange capacity that is comparable to that of the best commercial synthetic resins. This is demonstrated by its application to the removal of Pb, Cd, and Cu from water, in single and multicomponent systems. Maximum uptake was obtained at pH 5 and in the order Pb(II) > Cd(II) > Cu(II). The maximum adsorption of Pb was ~1.8 mmol/g, but the adsorption process resembled the Freundlich isotherm, whereas the adsorption of Cd(II) and Cu(II) followed the Langmuir isotherm. In the multicomponent systems, there was direct competition between Pb and Cd for sorption sites, whereas the results with Cu indicated it had a preference for different types of sites compared to Pb and Cd. The EDAR resin could be efficiently regenerated and used repeatedly with only a small decrease in performance. Characterization of EDAR, and investigations of its adsorption mechanisms using physical, spectroscopic, and theoretical techniques, including fourier transform infrared spectroscopy (FTIR), 13C nuclear magnetic resonance (13C NMR), scanning electron microscope (SEM), Brunauer Emmett Teller (BET) method, elemental analysis, thermogravimetric analysis (TGA), and molecular dynamics calculations, showed that amino groups have a critical role in determining the cation adsorption properties. We conclude that this new adsorbent derived from an abundant natural material has the potential to make valuable contributions to the routine removal of heavy metal ions (HMs) from drinking water and wastewater.

Adsorption of phenolic compounds from water by a novel ethylenediamine rosin-based resin: Interaction models and adsorption mechanisms.

This study describes the adsorption performance of a novel ethylenediamine rosin-based resin (EDAR) for several industrially-important phenolic compounds. Its removal of 4-nitrophenol (4-NP) from water was comparable to or better than many commercial resins, although it was less effective with other phenols (i. e., phenol, 2,4-dichlorophenol, 4-chlorophenol, and 4-methylphenol). Experimental conditions for batch adsorption of 4-NP by EDAR are evaluated, the adsorption kinetics is well described by the pseudo-second-order model (R2 > 0.99) and isotherm follows the Langmuir isotherm model (R2 > 0.99), with the maximum monolayer adsorption capacity of 82 mg g-1 at pH 6.0 and 293 K. The thermodynamic parameters indicate that the adsorption is spontaneous and endothermic. Also, quantum chemistry calculations indicate involvement of hydrogen-bonding between 4-NP and amino groups of EDAR. 4-NP was efficiently desorbed from the loaded EDAR resin by 0.2 M HCl, and the resin could be recycled with only a small decrease in its initial adsorption capacities. Thus, EDAR is a promising adsorbent for the removal of 4-NP during water treatment.

Quantitative determination of erythromycylamine in human plasma by liquid chromatography-mass spectrometry and its application in a bioequivalence study of dirithromycin.

A sensitive, rapid liquid chromatographic-electrospray ionization mass spectrometric method for determination of erythromycylamine in human plasma was developed and validated. Erythromycylamine in plasma (0.2 mL) was extracted with ethyl acetate, the organic phase was transferred to another clear 1.5 mL Eppendorf tube and evaporated to dryness under gentle nitrogen stream at 45 degrees C, and the residue was dissolved in 100 microL of mobile phase. The samples were separated using a Thermo Hypersil HyPURITY C18 reversed-phase column (150 mm x 2.1 mm I.D., 5 microm). A mobile phase containing 10 mM of ammonium acetate (pH = 6.4)-acetonitrile-methanol (50:10:40, v/v/v) was used isocratically eluting at a flow rate of 0.2 mL/min. Erythromycylamine and its internal standard (IS), midecamycin, were measured by electrospray ion source in positive selective ion monitoring mode. The method demonstrated that good linearity ranged from 4.5 to 720 ng/mL with r = 0.9997. The limit of quantification for erythromycylamine in plasma was 4.5 ng/mL with good accuracy and precision. The mean extraction recovery of the method was higher than 75.1% and 72.7% for erythromycylamine and IS, respectively. The intra-day and inter-day precision ranged from 5.2% to 6.4% and 5.6-9.3% (relative standard deviation, RSD), respectively. The established method has been successfully applied to a bioequivalence study of two dirithromycin formulations for 18 healthy volunteers.