Unveiling glutamic acid-functionalized LDHs: understanding the Cr(VI) removal mechanism from microscopic and macroscopic view points.

Interlayer functionalization modulation is essential for modifying LDHs and improving their selectivity and adsorption capacity for target pollutants. In this work, Glu@NiFe-LDH was synthesized using a simple one-step hydrothermal method and tested for its ability to remove CrO42- from wastewater. The modification significantly increased the composite material's removal ability by 2-3 times, up to 98.36 mg g-1. The behavior of CrO42- adsorption on Glu@NiFe-LDH was further studied by adjusting the affecting factors (i.e., temperature, pH, contact time, initial concentration, and interfering substance), and the adsorption behavior was confirmed as a spontaneous and chemisorption process. And the result was that Glu@NiFe-LDH demonstrated high capacity, efficiency, stability, and selectivity for the adsorption of CrO42- in a single electrolyte and natural water containing competing anions. Furthermore, molecular dynamics simulations (NVT ensemble) were employed to further reveal the mechanism of glutamic acid modification on LDH at the microscopic scale. Additionally, the IRI analysis method revealed the mechanism of weak interaction between glutamic acid molecules and CrO42-. This study provides a detailed understanding of the intercalation mechanism involved in the amino acid modification of LDHs. It explains the adsorption mechanism of metal oxo-acid radicals by amino acid-modified LDHs from a theoretical perspective. The findings offer experiments and a theoretical basis for designing targeted adsorbents in the future.

3D-Printed river-type thick carbon electrodes for docking possible practical application-level capacitive deionization.

The low carbon mass loading along with serious imbalance between the carbon mass loading and the electrode performance greatly hinders practical applications of capacitive deionization (CDI). Traditional thick bulk-type (BT) carbon electrodes often suffer from extremely limited active sites, thereby being vital to explore a basic strategy to unlock the performance. Herein, 3D-printed thick carbon electrodes were utilized for CDI desalination for the first time. The experimental outcomes revealed that BT electrodes existed a serious salt adsorption capacity (SAC) drop under variable mass loading of 3-30 mg/cm2. In contrary, 3D-printed river-type (RT) electrodes acquired a superior SAC of 10.67 mg/g and achieved 54.1 % SAC rise compared with that of BT electrodes (500 mg/L; 1.0 V; 30 mg/cm2). Meanwhile, RT electrodes took only 12 min to reach the equilibrium SAC of BT electrodes, being 44 min faster. Further, RT electrodes with diverse mass loading of 30-45 mg/cm2 were investigated, and it still kept 7.13 mg/g SAC under ultrahigh mass loading of 45 mg/cm2. This strategy has been successfully extended and carbons with proper micro-meso pore distribution, high specific capacitances and low resistance may be a better selection. Besides, the impact of electrode channel structure on the desalting performance was investigated, and the influence mechanism was revealed via COMSOL simulation. Overall, this work demonstrates the splendid feasibility of utilizing 3D-printed thick carbon electrodes for possible practical application-level CDI desalination.

Construction of ACNF/Polypyrrole/MIL-100-Fe composites with exceptional removal performance for ceftriaxone and indomethacin inspired by "Ecological Infiltration System".

Developing advanced adsorbents for removing the alarming level of pharmaceuticals active compounds (PhACs) pollution is an urgent task for environmental treatment. Herein, a novel acid-treated carbon nanofiber/polypyrrole/MIL-100-Fe (ACNF/PPy/MIL-100-Fe) with stable 3D-supporting skeleton and hierarchical porous structure had been fabricated to erasure ceftriaxone (CEF) and indomethacin (IDM) from aqueous solution. ACNF as scaffold achieved the highly uniform growth of MIL-100-Fe and PPy. Viewing the large BET surface area (SBET, 999.7 m2/g), highly exposed accessible active sites and copious functional groups, ACNF/PPy/MIL-100-Fe separately showed an excellent adsorption capacity for CEF (294.7 mg/g) and IDM (751.8 mg/g), outstripping the most previously reported adsorbents. Moreover, ACNF/PPy/MIL-100-Fe reached rapid adsorption kinetics and standout reusability property. Further, the redesigned easy-to-recyclable ACF/PPy/MIL-100-Fe inspired by the electrode formation craft achieved prominent adsorption capacity and good reusability property. The adsorption mechanism was evaluated via Fourier transformed infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The outcomes revealed that the splendid adsorption capability mainly depended on the electrostatic interactions, hydrogen bonding and π-π interactions. This work sheds light on one facile practical strategy to exploit advanced materials in water environmental remediation.

The effects of grain size and temperature on mechanical properties of CoCrNi medium-entropy alloy.

CONTEXT: The mechanical properties and deformation mechanisms of CoCrNi medium-entropy alloy are studied through molecular dynamics simulations. The effects of temperature and average grain size on the elastic modulus, Poisson's ratio, yield stress, and maximum flow stress are investigated. METHODS: The constant pressure molecular dynamics method is used to calculate the elastic modulus and Poisson's ratio of the alloy at different temperatures and average grain sizes. Simple tension simulations are conducted to determine the yield stress and maximum flow stress as a function of average grain size. The study also analyzes the dislocation behavior near grain boundaries at different temperatures using molecular dynamics simulations. The Hall-Petch and inverse Hall-Petch relationships are employed to describe the grain size-dependent deformation behavior of the alloy.

Investigation of the adsorption performance and mechanism of 2-mercaptoethane sulfonic acid intercalated modified layered double hydroxide on heavy metal ions.

In the adsorption process of functionalized layered double hydroxide (LDH) to target pollutants it, is essential to investigate the role of functional groups. In this work, 2­mercaptoethane sulfonic acid (MS) was used as an intercalation modifier to prepare functionalized NiFe-LDH by solvothermal method. The interfacial interaction between the functional groups and the NiFe-LDH surface was studied via molecular dynamics simulation. During the intercalation process, the more negatively charged sulfonic acid group tends to self-assemble electrostatically with the LDH laminate, while the sulfhydryl group is involved in complexing heavy metal ions. The adsorption experiments showed that the adsorption performance of the adsorbent for the three ions of Cd2+, Mn2+, and Co2+ at 298.15 K was 266.16 mg/g, 175.60 mg/g, and 106.56 mg/g, respectively, which were 10 times, 8.7 times, and 4.9 times higher than that of unmodified NiFe-LDH. Meanwhile, Multiwfn wavefunction analysis combined Visual Molecular Dynamics (VMD) was applied to analyze and visualize the reaction active sites & the interactions between MS and NiFe-LDH, and the complexation of the functional group of MS with metal ions, to insight the role of the functional groups in MS molecule, and to reveal the cause that the adsorption capacity of modified NiFe-LDH for heavy metals greatly improves from the view of atoms.

Smart Adhesives via Magnetic Actuation.

Smart adhesives possess a wide range of applications owing to their reversibly and repeatedly switchable adhesion in transfer technology. Despite recent advances, it still remains a technical and scientific challenge to achieve strategies for rapidly tunable adhesion in a noncontact manner. In this study, a smart adhesive to achieve dynamically tunable adhesion is developed. Specifically, a mushroom-shaped adhesive with a magnetized tip is actuated to reversibly and rapidly transform the morphology via magnetic actuation. The smart adhesive has two working modes, namely, selective pickup mode and pick-and-place mode. In the selective pickup mode, the external magnetic field is applied and the tip undergoes bending deformation. Changes in tip morphology allow for a reversible switch of the adhesion between "turn on" and "turn off." In the pick-and-place mode, the external magnetic field is applied when the target object needs to be released. Upward bending deformation of the micro-beam, a part of the tip, creates an initial crack at the edge of the adhesion interface. The propagation of the edge crack modulates the adhesion from strong to weak and the target object is instantly released. The proposed smart adhesive may be of interest for practical applications demanding highly precise and swiftly controlled movements.

Facile immobilization of ethylenediamine tetramethylene-phosphonic acid into UiO-66 for toxic divalent heavy metal ions removal: An experimental and theoretical exploration.

By the facile immobilization of ethylenediamine tetramethylene-phosphonic acid (EDTMPA) onto the surface and into the defects of UiO-66, a stable and efficient adsorbent named UiO-66-EDTMPA was obtained for the first time. In terms of removing aqueous heavy metal ions (Pb2+, Cd2+, Cu2+), the maximum adsorption capacities of UiO-66-EDTMPA reached 558.67, 271.34 and 210.89 mg/g, which were 8.77 (Pb2+), 5.63 (Cd2+) and 5.19 (Cu2+) times higher than raw UiO-66 respectively. The adsorption behavior of three heavy metal ions on UiO-66 and UiO-66-EDTMPA were investigated and compared through batch control experiments and theoretical studies. The main factors on adsorption progress (i.e., the dosage of EDTMPA, pH, ionic strength, co-existing ions, initial concentration, contact time, temperature) were explored, and the critical characterization (i.e., SEM, TEM, XRD, FT-IR, TG-DTG, XPS, N2 adsorption-desorption test) were performed. Molecular dynamics (MD) simulation (radial distribution functions (RDF) and mean square displacement (MSD)) were also applied to reveal the adsorption behavior. Besides, two new quantum chemical analyses (Hirshfeld surface and independent gradient model (IGM)) were introduced into the interaction analysis between UiO-66 and EDTMPA. The complete results showed that (1) where the hydrogen bond and (vdW) connect EDTMPA to UiO-66. (2) The coordination between O, N atoms of EDTMPA and heavy metal ions (Pb2+, Cd2+, Cu2+) resulted in spontaneous adsorption. (3) The adsorption behavior agreed with Langmuir and pseudo-second-order model, endothermic reaction. In addition, the desorption and reusability study showed promising stable and sustainable performance. This work has some guiding significance for the experimental and theoretical study of removing heavy metal ions from aqueous solutions by MOF or modified MOF materials.

Peroxymonosulfate activation through 2D/2D Z-scheme CoAl-LDH/BiOBr photocatalyst under visible light for ciprofloxacin degradation.

The synergistic effect between photocatalytic and peroxymonosulfate (PMS) activation has been widely applied in the field of sewage treatment. In this work, we synthesized a two-dimensional/two-dimensional (2D/2D) CoAl-LDH/BiOBr Z-scheme photocatalyst via a simple method. Then, multiple detection results demonstrated that CoAl-LDH was successfully anchored onto BiOBr, as well as formed an intimate interaction. Moreover, the photocatalytic degradation performance of the catalysts/PMS/vis system had been explored under several conditions (e.g., different catalyst doses, PMS doses, anions and pollutants). The 8 wt% CoAl-LDH/BiOBr composite exhibited the highest degradation efficiency (96%) of ciprofloxacin (CIP). In addition, radicals quenching experiments and electron paramagnetic resonance (EPR) indicated that •O2- and 1O2 were the primary radicals for CIP degradation. The photoelectrochemical measurement and photoluminescence (PL) confirmed that 8 wt% CoAl-LDH/BiOBr exhibited the highest separation and transfer rate of charge carriers. The liquid chromatography-mass spectrometer (LC-MS) analysis revealed that oxidation of the piperazine ring and defluorination were the main CIP degradation pathways. Density functional theory (DFT) calculation, including the laplacian bond order (LBO) and Fukui index, which was consistent with the results of LC-MS. This study explained the superiority of the synergistic effect between photocatalysis and PMS activation on the degradation of pollutants.

Adsorption of two ß-blocker pollutants on modified montmorillonite with environment-friendly cationic surfactant containing amide group: Batch adsorption experiments and Multiwfn wave function analysis.

The novel environment-friendly hexadecanoamide propyltrimethy lammonium chloride (NQAS16-3) surfactant with different amounts (0.2, 0.4, 0.6, 0.8, 1.0, 1.2 CEC) was firstly used to modify montmorillonite, and the obtained organomontmorillonite (N-Mt) with the amount of surfactant equal to 1.0 CEC was utilized to adsorb two ß-blocker pollutants- Atenolol (ATE) and acebutolol (ACE). The experimental results indicated that the equilibrium adsorption capacity of N-Mt(the organo-montmorillonite that the amount of modifier was 1.0 CEC) for ATE and ACE was 93.47 mg/g and 84.55 mg/g, respectively, which was more than twice that of raw montmorillonite for two pollutants, the adsorption was better fitted with the pseudo-second-order model and Langmuir isotherms model, and the adsorption was the spontaneous and exothermic process. Moreover, combining with the Zeta potential values of N-Mt, and with the help of Multiwfn wave function program based on density functional theory (DFT), the electrostatic interaction and the hydrophobic partitioning between N-Mt and two pollutant molecules were verified, p-π/π interaction between NQAS16-3 and ATE (or ACE) may be contributed to the increasing adsorption capacity of N-Mt for two ß-blocker pollutants. The work provided novel organomontmorillonite for the removal of non-degradable ß-blocker pollutants and the insight of the adsorption mechanism from the atomic level.

Synthesis and evaluation of antitumor activities of 4-selenopyrimidine derivatives.

Pyrimidine antimetabolic agents are the essential drugs in treatment of various tumors. Novel synthesis and biological evaluation of the pyrimidine derivatives incorporating selenium element and amino acid carrier as potential antitumor agents have not been tried and studied. Based on the biological significance of pyrimidine structure, these two additional elemental fragments maybe enhance the antitumor effect and reduce toxic side effects of pyrimidine agents. The aim of this paper is to synthesis a series of 4-selenopyrimidine derivatives in order to find more potent lead compounds against cancer. In this study, 12 new 4-selenopyrimidine derivatives that are unstable in acidic solutions but very stable in alkaline and neutral solutions avoiding light were synthesized, and the antitumor activities on HepG2 cell lines of these compounds were evaluated by MTT assay. The results have shown that these compounds could reduce the proliferation of HepG2 cells in a dose-dependent fashion, and the inhibitory activity of compounds a6 was greater than that of positive control 5-fluorouracil (5-FU), the IC50 for a6 was 3.63 µM. In the comprehensive analysis of the structure-activity relationship, we could draw the antitumor effect of selenouracil derivatives is stronger than those of selenothymine derivatives. These results suggest that the substituent groups of selenium element and amino acid on the pyrimidine derivatives are vital for their antitumor activities on HepG2 cells.

OsCASP1 forms complexes with itself and OsCASP2 in rice.

OsCASP1 (Casparian strip domain protein 1) was recently identified to function in Casparian strip (CS) formation at the endodermal cells in rice roots, which was required for selective mineral uptake in rice. Here, we further investigate the functional form of OsCASP1 in vivo. Expression analysis shows that OsCASP1, OsCASP2, OsCASP3, and OsCASP5 were expressed in roots apart from OsCASP4. A yeast two-hybrid (Y2H) assay revealed that OsCASP1 can interact with itself and OsCASP2, but not with OsCASP3 and OsCASP5. These interactions of OsCASP1 with itself and OsCASP2 at the plasma membrane were confirmed using bimolecular fluorescence complementation (BiFC) in rice protoplasts. These results indicated that OsCASP1 can form complexes with itself and OsCASP2 in rice roots.

OsCASP1 Is Required for Casparian Strip Formation at Endodermal Cells of Rice Roots for Selective Uptake of Mineral Elements.

In response to diverse environmental conditions, rice (Oryza sativa) roots have developed one Casparian strip (CS) at the exodermis and one CS at the endodermis. Here, we functionally characterized OsCASP1 (Casparian strip domain protein 1) in rice. OsCASP1 was mainly expressed in the root elongation zone, and the protein encoded was first localized to all sides of the plasma membrane of endodermal cells without CS, followed by the middle of the anticlinal side of endodermal cells with CS. Knockout of OsCASP1 resulted in a defect of CS formation at the endodermis and decreased growth under both soil and hydroponic conditions. Mineral analysis showed that the oscasp1 mutants accumulated more Ca, but less Mn, Zn, Fe, Cd, and As in the shoots compared with the wild type. The growth inhibition of the mutants was further aggravated by high Ca in growth medium. The polar localization of the Si transporter Low Si 1 at the distal side of the endodermis was not altered in the mutant, but the protein abundance was decreased, resulting in a substantial reduction in silicon uptake. These results indicated that OsCASP1 is required for CS formation at the endodermis and that the CS in rice plays an important role in root selective uptake of mineral elements, especially Ca and Si.

The ABC transporter ABCG36 is required for cadmium tolerance in rice.

Cadmium (Cd) is a highly toxic heavy metal in nature, which causes severe damage to plant growth. The molecular mechanisms for Cd detoxification are poorly understood. Here, we report that a G-type ATP-binding cassette transporter, OsABCG36, is involved in Cd tolerance in rice. OsABCG36 was expressed in both roots and shoots at a low level, but expression in the roots rather than the shoots was greatly up-regulated by a short exposure to Cd. A spatial expression analysis showed that Cd-induced expression of OsABCG36 was found in both the root tip and the mature root region. Transient expression of OsABCG36 in rice protoplast cells showed that it was localized to the plasma membrane. Immunostaining showed that OsABCG36 was localized in all root cells except the epidermal cells. Knockout of OsABCG36 resulted in increased Cd accumulation in root cell sap and enhanced Cd sensitivity, but did not affect tolerance to other metals including Al, Zn, Cu, and Pb. The concentration of Cd in the shoots was similar between the knockout lines and wild-type rice. Heterologous expression of OsABCG36 in yeast showed an efflux activity for Cd, but not for Zn. Taken together, our results indicate that OsABCG36 is not involved in Cd accumulation in the shoots, but is required for Cd tolerance by exporting Cd or Cd conjugates from the root cells in rice.

Disruption of an amino acid transporter LHT1 leads to growth inhibition and low yields in rice.

BACKGROUND: Research on plant amino acid transporters was mainly performed in Arabidopsis, while our understanding of them is generally scant in rice. OsLHT1 (Lysine/Histidine transporter) has been previously reported as a histidine transporter in yeast, but its substrate profile and function in planta are unclear. The aims of this study are to analyze the substrate selectivity of OsLHT1 and influence of its disruption on rice growth and fecundity. RESULTS: Substrate selectivity of OsLHT1 was analyzed in Xenopus oocytes using the two-electrode voltage clamp technique. The results showed that OsLHT1 could transport a broad spectrum of amino acids, including basic, neutral and acidic amino acids, and exhibited a preference for neutral and acidic amino acids. Two oslht1 mutants were generated using CRISPR/Cas9 genome-editing technology, and the loss-of-function of OsLHT1 inhibited rice root and shoot growth, thereby markedly reducing grain yields. QRT-PCR analysis indicated that OsLHT1 was expressed in various rice organs, including root, stem, flag leaf, flag leaf sheath and young panicle. Transient expression in rice protoplast suggested OsLHT1 was localized to the plasma membrane, which is consistent with its function as an amino acid transporter. CONCLUSIONS: Our results indicated that OsLHT1 is an amino acid transporter with wide substrate specificity and with preference for neutral and acidic amino acids, and disruption of OsLHT1 function markedly inhibited rice growth and fecundity.

Bioinformatic and Functional Analysis of a Key Determinant Underlying the Substrate Selectivity of the Al Transporter, Nrat1.

Nrat1 is a member of the natural resistance-associated macrophage protein (Nramp) family of metal ion transporters in all organisms. Different from other Nramp members capable of transporting divalent metals, Nrat1 specifically transports trivalent aluminum (Al) ion. However, molecular mechanism underlying the Al transport selectivity of Nrat1 remains unknown. Here, we performed structure-function analyses of Nrat1 and other Nramp members to gain insights into the determinants of ion selectivity. A phylogenetic analysis showed that plant Nramp transporters could be divided into five groups. OsNrat1 was found in one of the individual clades and clustered with SbNrat1 and ZmNrat1 on the evolutionary tree. Structural modeling revealed that Nrat1 transporters adopted a common LeuT fold shared by many Nramp-family transporters that likely employed an identical transport mechanism. Sequence alignment and evolutionary conservation analysis of amino acids identified a metal-permeation pathway of Nrat1 centered at the metal binding site. The metal binding site of Nrat1 was characterized by two conserved sequence motifs, i.e., the Asp-Pro-Ser-Asn motif (motif A) and the Ala-Ile-Ile-Thr motif (motif B). Replacement of the Ala-Met-Val-Met motif B of the OsNramp3 manganese (Mn) transporter to that of Nrat1 resulted in a partial gain of Al transport activity and a total loss of Mn in yeast. Conversely, substitution of the motif B of OsNrat1 with that of OsNramp3 altered the Al transport activity. These observations indicated the metal binding site, particularly the motif B, as a key determinant of Al selectivity of Nrat1.

Functional characterization of the SbNrat1 gene in sorghum.

The Natural Resistance Associated Macrophage Protein (Nramp) members play diverse roles in metal transport in plants. Recent studies have showed that OsNrat1 (OsNramp4) encodes an Al transporter, which is required for rice Al tolerance. In this study, we functionally characterized a Nramp member in sorghum, SbNrat1, which is homologous to OsNrat1 with 88% identity. SbNrat1 was expressed in both roots and shoots, and its expression was not induced by Al treatment. When expressed in yeast, SbNrat1 transports trivalent Al ion, but not Mn and Cd. Furthermore, introduction of SbNrat1 into the rice mutant osnrat1 can rescue its sensitivity to Al. However, no correlation between Al tolerance and the expression level of SbNrat1 was found in thirteen sorghum cultivars tested. These results indicate that SbNrat1 functions as an Al transporter that is possibly involved in basic Al tolerance in sorghum.

Combined dry and wet adhesion between a particle and an elastic substrate.

We theoretically model the combined dry and wet adhesion between a rigid sphere and an elastic substrate, where the dry contact area is surrounded by a liquid meniscus. The influence of the liquid on the interfacial adhesion is twofold: inducing the Laplace pressure around the dry contact area and altering the adhesion energy between solid surfaces. The behavior of such combined dry and wet adhesion shows a smooth transition between the JKR and DMT models for hydrophilic solids, governed by the prescribed liquid volume or environmental humidity. The JKR-DMT transition vanishes when the solids become hydrophobic. An inverse scaling law of adhesive strength indicates that size reduction helps to enhance the adhesive strength until a theoretical limit is reached. This study also demonstrates the jumping-on and jumping-off hysteresis between the combined dry-wet adhesion and pure liquid bridge in a complete separation and approach cycle.

Metformin combined with p38 MAPK inhibitor improves cisplatin sensitivity in cisplatin­resistant ovarian cancer.

The aim of the present study was to determine the effects of metformin, combined with a p38 mitogen­activated protein kinase (MAPK) inhibitor, on the sensitivity of cisplatin­resistant ovarian cancer to cisplatin. The expression and distribution of phosphorylated p38 MAPK (P­p38 MAPK) was confirmed in drug­resistant and primary ovarian cancer tissues by immunohistochemistry and western blotting. A bromodeoxyuridine ELISA kit was used to analyze the effects of metformin, SB203580, a p38 MAPK inhibitor, and metformin combined with SB203580, on the cell proliferation of SKOV3/DDP cisplatin­resistant ovarian cancer cells. The protein expression of P­p38 MAPK was significantly higher in cisplatin­resistant ovarian cancer, as compared with the primary ovarian cancer tissues. Metformin combined with SB203580 significantly enhanced the sensitivity of SKOV3/DDP cells to cisplatin. In conclusion, the p38 MAPK signaling pathway may be associated with cisplatin­resistant ovarian cancer. Metformin, combined with the p38 MAPK inhibitor, significantly increased the sensitivity of SKOV3/DDP cells to cisplatin treatment.

Ultrathin conformal devices for precise and continuous thermal characterization of human skin.

Precision thermometry of the skin can, together with other measurements, provide clinically relevant information about cardiovascular health, cognitive state, malignancy and many other important aspects of human physiology. Here, we introduce an ultrathin, compliant skin-like sensor/actuator technology that can pliably laminate onto the epidermis to provide continuous, accurate thermal characterizations that are unavailable with other methods. Examples include non-invasive spatial mapping of skin temperature with millikelvin precision, and simultaneous quantitative assessment of tissue thermal conductivity. Such devices can also be implemented in ways that reveal the time-dynamic influence of blood flow and perfusion on these properties. Experimental and theoretical studies establish the underlying principles of operation, and define engineering guidelines for device design. Evaluation of subtle variations in skin temperature associated with mental activity, physical stimulation and vasoconstriction/dilation along with accurate determination of skin hydration through measurements of thermal conductivity represent some important operational examples.