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Aqueous biphasic systems (ABSs) based on sodium polyacrylate (NaPA), ethylene oxide/propylene oxide (EO/PO) polymers, and (EO)x-(PO)y-(EO)x triblock copolymers were prepared and applied aiming at continuous fructooligosaccharide (FOS) production and separation. EO/PO hydrophilicity/hydrophobicity balance had a significant effect on ABS formation. To develop an integrated process including the continuous enzymatic (levansucrase) production of FOSs and their purification while improving the production yield by further glucose separation, the potential of these novel polymer-based ABSs as alternative platforms was investigated. They were used for the partitioning of different carbohydrates (FOS, sucrose, d-fructose, and d-glucose) and levansucrase. Results revealed a highly polymer-dependent partition of carbohydrates and a poorly dependent one of the enzymes. Changing EO/PO and copolymers, FOS was purified with high yields (72.94-100.0%). Using polypropylene glycol 400 + NaPA 8000-based ABS, the FOS was precipitated in the interphase and separated from the other components. Pluronic PE-6800 + NaPA 8000 was identified as the best ABS for FOS continuous production and in situ purification, while minimizing levansucrase inhibition by d-glucose. This system allowed selective partition of FOSs and d-glucose toward the top phase and that of levansucrase and its substrates toward the bottom one. COnductor-like Screening MOdel for Real Solvent (COSMO-RS) suggested that ABS formation may have been due to NaPA and polymer/copolymer competition to form hydrogen bonds with water molecules. Moreover, the partition of FOSs and sugar may have been the result of a subtle balance between hydrogen bonding of sugar and polymer/copolymer and electrostatic misfit of solute with NaPA. Finally, two integrated processes were proposed to be applied with real FOS extracts obtained by chemical or enzymatic hydrolysis of inulin or by transfructosylation of concentrated sucrose solutions using bacterial levansucrases. published

Hybrid materials, integrating the merits of individual components, are ideal structures for efficient oxygen evolution reaction (OER). However, the rational construction of hybrid structures with decent physical/electrochemical properties is yet challenging. Herein, a promising OER electrocatalyst composed of trimetallic metal-organic frameworks supported over S/N-doped carbon macroporous fibers (S/N-CMF@FexCoyNi1-x-y-MOF) via a cation-exchange strategy is delicately fabricated. Benefiting from the trimetallic composition with improved intrinsic activity, hollow S/N-CMF matrix facilitating exposure of active sites, as well as their robust integration, the resultant S/N-CMF@FexCoyNi1-x-y-MOF electrocatalyst delivers outstanding activity and stability for alkaline OER. Specifically, it needs an overpotential of 296 mV to reach the benchmark current density of 10 mA cm−2 with a small Tafel slope of 53.5 mV dec−1. In combination with X-ray absorption fine structure spectroscopy and density functional theory calculations, the post-formed Fe/Co-doped γ-NiOOH during the OER operation is revealed to account for the high OER performance of S/N-CMF@FexCoyNi1-x-y-MOF. Ministry of Education (MOE) Submitted/Accepted version X.W.L. acknowledges the funding support from the Ministry of Education of Singapore through the Academic Research Fund (AcRF) Tier-2 grant (MOE2019-T2-2-049).

Kovinsko-organski mikroporozni materiali (ang. metal–organic frameworks ali MOF) sodijo med najbolj obetavne adsorbente za zajem CO2. V doktorskem delu sem podrobnopreučila tri strukturne tipe za ta namen, in sicer HKUST-1, ZnBDC in MOF-74. V prvem delu doktorskega dela sem se posvetila študiju vpliva modifikacije ogrodja HKUST-1 z etilendiaminom (ED) na jakost interakcije molekule CO2 z ogrodjem, selektivnost ogrodja za CO2 iz binarne mešanice plinov CO2/N2 ter kinetiko adsorpcije. Ugotovila sem, da modifikacija izboljša jakosti interakcije molekule CO2 z ogrodjem in selektivnosti ogrodja za adsorpcijo CO2 za 85 %, pri čemer sta oba parametra tesno povezana s poroznostjo materiala in dostopnostjo por. Večanje količine dodanega ED vpliva na nastanek t.i. hierarhičnega sistema por, kar nadalje izboljša tudi difuzijo in hitrost adsorpcije molekul CO2 v ogrodje modificiranih materialov. V drugem delu sem preučevala strukturo ZnBDC z negativno nabitim ogrodjem, katerega naboj kompenzirajo v porah prisotni di- in trimetilamonijevi kationi. Z namenom, da bi izboljšala tako sorpcijske kot tudi katalitske lastnosti izhodiščnega vzorca, sem izvedla ionsko izmenjavo v ogrodju ujetih kationov s kationi natrija, kalija, litija in magnezija. Glede na izhodiščni material, imajo ionsko izmenjani vzorci višjo adsorpcijsko kapaciteto za CO2, sorpcijske lastnosti pa se izboljšujejo z manjšanjem radija izmenjanih kationov. Ionska izmenjava vpliva tudi na povečanje katalitske aktivnosti, saj je osnovni ZnBDC katalitsko skoraj neaktiven, medtem ko Mg-ZnBDC brez uporabe ko-katalizatorja, ob prisotnosti CO2, uspešno pretvori približno 40 % propilen oksida v propilen karbonat. V tretjem sklopu doktorskega dela sem, z namenom lažjega rokovanja, M-MOF-74 (M=Zn, Co, Mg) pripravila v polimerni matrici poliHIPE s pomočjo sekundarne prekristalizacije iz kovinskih oksidov. Ugotovila sem, da vrsta kovinskih kationov v ogrodni strukturi, ne vpliva na uspešnost kristalizacije MOF-74 v polimerni matriki. Nadalje sem preučila dostopnost vgrajenega MOF-74 za adsorpcijo molekul CO2, ta je v primeru Mg-MOF-74@poliHIPE 98.6 %. Rezultati sorpcije CO2 so pokazali, da imajo prekristalizirani vzorci glede na delež vgrajenega MOF-a višje adsorpcijske kapacitete za CO2 ter da je kinetika adsorpcije in desorpcije v polimernih kompozitih boljša kot v praškastih vzorcih. Poleg kinetike sem z vgradnjo MOF-74 v polimerno matrico izboljšala tudi regeneracijo adsorbentov – pri temperaturi 150 °C se v primeru vzorca Zn-MOF-74@polyHIPE uspešno desorbira do 95 % CO2. Metal-organic frameworks (MOFs) are one of the most promising materials for CO2 capture and conversion. In my research, I have focused on three systems with high CO2 capture capabilities – HKUST-1, ZnBDC and MOF-74. The first part of my research was focused on the studies of HKUST-1 framework functionalization with ethylenediamine (ED) and the impact of the modification process on the CO2 capture parameters relevant for the post-combustion process. In the case of the modified materials, the isosteric heat of adsorption and CO2/N2 selectivity was improved by almost 85 %. Both parameters are closely related to the materials porosity and pore accessibility. The increase of ED loading caused the formation of hierarchical structure expanded over micro-, meso- and macropore range, which further improved the adsorption kinetics and diffusion of CO2 molecules within the framework of modified materials. In the second part of this research, I investigated the effect of cation exchange on the CO2 capture and conversion performances of the negatively charged ZnBDC framework, which was initially compensated by di- and trimethylammonium cations located within the material pores. The cation exchange was performed using sodium, potassium, lithium and magnesium cations to improve sorption and catalytic properties of the pristine material. In comparison with the pristine ZnBDC, all modified materials exhibited higher CO2 adsorption capacities, and the sorption properties are improved by decreasing the cation radius. The ionic exchange also had a positive effect on catalytic activity in comparison with the pristine ZnBDC, which was almost catalytically inactive, the exchanged materials exhibit significant improvement. Namely, Mg-modified material exhibited a 40% higher conversion of propylene oxide to propylene carbonate without the use of co-catalyst. The final part of the thesis is dedicated to the shaping of MOF materials by secondary recrystallization of metal-oxide initially incorporated in a polymeric matrix (polyHIPE) into M-MOF-74 (M=Zn, Co, Mg). All metal oxide precursors were efficiently recrystallized to MOF-74. Furthermore, incorporated MOF-74 phases exhibit unobstructed accessibility for the CO2 adsorption reaching up 98.6 % for the case of Mg-MOF-74@polyHIPE. All immobilized MOF-74 phases also showed an improvement in adsorption kinetics and temperature swing adsorption regeneration efficiency performed at 150 °C (up to 95 % for Zn-MOF-74@polyHIPE).

A comprehensive scientometric approach was adopted to study the research on ion exchange membranes. The statistical analysis was conducted based on 21 123 publications which were related to the topic of ion exchange membranes. Specifically, from 2001 to 2016, over 18 000 articles were published on ion exchange membranes, indicating researchers' great interest in this topic. Especially, compared to 2001, the number of articles published in 2016 increased approximately six-fold. This trend continued in 2017 since over 2000 articles were published in the year of 2017. Also, these articles were spread across over 1000 different journals, near 100 countries/regions and over 5000 research institutes, revealing the importance of ion exchange membrane as well as the broad research interest in this field. Besides, the properties and applications of ion exchange membranes were also discussed statistically. Furthermore, keywords analysis indicated that fuel cell and proton exchange membrane had the highest cooccurrence frequency. Finally, research areas analysis revealed that ion exchange membranes had a close relation with chemistry, energy and materials.

Human IgG is produced with C-terminal lysines that are cleaved off in circulation. The function of this modification was unknown and generally thought not to affect antibody function. We recently reported that efficient C1q binding and complement-dependent cytotoxicity (CDC) requires IgG hexamerization at the cell surface. Here we demonstrate that C-terminal lysines may interfere with this process, leading to suboptimal C1q binding and CDC of cells opsonized with C-terminal lysine-containing IgG. After we removed these lysines with a carboxypeptidase, maximal complement activation was observed. Interestingly, IgG1 mutants containing either a negative C-terminal charge or multiple positive charges lost CDC almost completely; however, CDC was fully restored by mixing C-terminal mutants of opposite charge. Our data indicate a novel post-translational control mechanism of human IgG: human IgG molecules are produced in a pro-form in which charged C-termini interfere with IgG hexamer formation, C1q binding and CDC. To allow maximal complement activation, C-terminal lysine processing is required to release the antibody's full cytotoxic potential.

PubMed ID: 29778445, New cation exchanger monolithic stationary phases were prepared by immobilization of three different calixarene derivatives (i.e. tetracarboxylate calix[4]arene, CLX-COO, tetrasulfonate calix[4]arene, CLX-SO3, and tetraphosphonate calix[4]arene, CLX-PO4) onto a monolithic cryogel support (i.e. poly(2-hydroksyethylmethacrilate-co-glycidyl methacrylate, P) and investigated with respect to preparative protein chromatography. The obtained monoliths were characterized through various techniques such as FTIR spectroscopy, isoelectric point measurements, titrimetric analyses, and mercury intrusion porosimetry. Protein retention was investigated using some model proteins (i.e. lysozyme, cytochrome c, and ?-chymotrypsinogen A, human serum albumin, and myoglobin), and the role of modifier (i.e. NaCl) concentration and pH was thoroughly analyzed under isocratic and gradient elution conditions. Overloading experiments were also conducted to study dynamic adsorption capacity and the obtained values were found to be ranging between 3 and 8 mg/mL depending on the type of calixarene molecule. Hence, higher or comparable protein adsorption capacities were seen to be applicable on calixarene-immobilized cryogels when compared to any other functionalized cryogels in the literature. Combined with the favorable properties of these monoliths, with respect to mass transport of large molecules, these results qualify calixarene functionalized monolithic cryogels as promising stationary phases for protein preparative purification. © 2018 Elsevier B.V., Authors wish to thank TÜBİTAK (The Scientific and Technological Research Council of Turkey) for the financial support provided (Project number: 115Z236). Authors also wish to thank Nigde Ömer Halisdemir University, Karamanoglu Mehmetbey University, and ETH Zürich University for the facilities provided. Appendix A

Surface chemistry bridges the gap between nanocrystal synthesis and their applications. In this respect, the discovery of complex ligand binding motifs on semiconductor quantum dots and metal oxide nanocrystals opens a gateway to new areas of research. The implications are far-reaching, from catalytic model systems to the performance of solar cells.

As research, development, and manufacturing of biosimilar protein therapeutics proliferates, there is great interest in the continued development of a portfolio of complementary analytical methods that can be used to efficiently and effectively characterize biosimilar candidate materials relative to the respective reference (i.e., originator) molecule. Liquid phase separation techniques such as liquid chromatography and capillary electrophoresis are powerful tools that can provide both qualitative and quantitative information about similarities and differences between reference and biosimilar materials, especially when coupled with mass spectrometry. However, the inherent complexity of these protein materials challenges even the most modern one-dimensional (1D) separation methods. Two-dimensional (2D) separations present a number of potential advantages over 1D methods, including increased peak capacity, 2D peak patterns that can facilitate unknown identification, and improvement in the compatibility of some separation methods with mass spectrometry. In this study, we demonstrate the use of comprehensive 2D-LC separations involving cation-exchange (CEX) and reversed-phase (RP) separations in the first and second dimensions to compare 3 reference/biosimilar pairs of monoclonal antibodies (cetuximab, trastuzumab and infliximab) that cover a range of similarity/disimilarity in a middle-up approach. The second dimension RP separations are coupled to time-of-flight mass spectrometry, which enables direct identification of features in the chromatograms obtained from mAbs digested with the IdeS enzyme, or digestion with IdeS followed by reduction with dithiothreitol. As many as 23 chemically unique mAb fragments were detected in a single sample. Our results demonstrate that these rich datasets enable facile assesment of the degree of similarity between reference and biosimilar materials.

We present a design principle to develop new categories of telluride-based thermoelectric nanowire heterostructures through rational solution-phase reactions. The catalyst-free synthesis yields Te-Bi(2)Te(3) "barbell" nanowire heterostructures with a narrow diameter and length distribution as well as a rough control over the density of the hexagonal Bi(2)Te(3) plates on the Te nanowire bodies, which can be further converted to other telluride-based compositional-modulated nanowire heterostructures such as PbTe-Bi(2)Te(3). Initial characterizations of the hot-pressed nanostructured bulk pellets of the Te-Bi(2)Te(3) heterostructure show a largely enhanced Seebeck coefficient and greatly reduced thermal conductivity, which lead to an improved thermoelectric figure of merit. This approach opens up new platforms to investigate the phonon scattering and energy filtering.

The effect of physicochemical parameters such as pH, salinity (e.g. [NaCl]) and competitive cation (e.g. Ca 2+ and Fe 3+) concentration on the separation recovery of plutonium and uranium from aqueous solutions by cation exchange has been investigated. The investigation was performed to evaluate the applicability of cation exchange as separation and pre-concentration method prior to the radiometric analysis of uranium and plutonium isotopes in natural water samples. Application of the method to test solutions of constant radionuclide concentration and variable composition (0.1, 0.5 and 1 M NaCl 0.1 and 0.5 M Ca(NO 3) 2 0.1 and 1 mM FeCl 3 10) has generally shown that: (1) the optimum pH is 4.5 for uranium and plutonium, (2) increasing salinity results in slightly lower for uranium and significantly higher chemical recovery plutonium and (3) the presence of Ca(II) cations doesn't significantly affect the chemical recovery of both radionuclides. Contrary, the presence of Fe(III) cations ([Fe(III)] > 0.1 mM) results in significantly lower chemical recovery for both radionuclides (Cited By :2

The Diels-Alder cycloaddition reactions between cyclopentadiene and methacrolein are effectively catalyzed with the aluminum-modified mesoporous silica MCM-41 having a variety of metal cations in the pore such as Zn-,Co-,Ni- and La-MCM-41.The β zeolite (H-β)having protons in the pore shows a dramatically high catalytic activity in the same reaction to give a quantitative yield of cycloadducts at 0℃ in less than l h, and the dealuminated β zeolite is also a highly reactive catalyst.The Diels-Alder reactions of cyclopentadiene with 3-buten-2-one and 2-ethylacrolein are also activated with the H-β and Ni-MCM-41

Good’s buffer ionic liquids (GB-ILs) are new class of ILs with self-buffering capacity at the physiological pH range for biological research. GB-ILs are formed by the combination of Good’s buffers as anions and various organic bases as counter ions. In this work, the complexation of europium(III) ion with tricine and tricine-based GB-ILs, tetramethylammonium tricinate, tetraethylammonium tricinate, tetrabutylammonium tricinate, cholinium tricinate, and 1-ethyl-3-methylimidazolium tricinate in aqueous solution were determined potentiometrically at T = 298.2 K and ionic strength I = 0.1 mol · dm−3 NaNO3. The protonation constants of the studied ligands (L) and their overall stability constants ( lg β ) with Eu(III) were determined. The best model that fit the potentiometric data was consisted of six main species, EuL 2 + , EuL 2 + , EuL 3 , EuH - 1 L + , EuH - 2 L 2 - , and EuH - 3 L 3 3 - . The lg β Eu ( tricine ) , lg β Eu ( tricine ) 2 , and lg β Eu ( tricine ) 3 are 5.75, 9.51, and 12.79, respectively. The overall stability constants ( lg β ) of tricine-based GB-ILs were found to be greater than those of tricine. The species distribution diagrams of these complexes were calculated and discussed in terms of percent Eu(III) and pH. We present a density functional theory (DFT) study to understand tricine chelating to Eu(III).

Submitted by Celso Magalhaes (celsomagalhaes@ufrrj.br) on 2019-11-21T14:03:47Z No. of bitstreams: 1 2015 - Ana Cristina Miranda Senna Gouv?a.pdf: 13924664 bytes, checksum: 4ac5eb037aa43029293669dc68b06137 (MD5) Made available in DSpace on 2019-11-21T14:03:47Z (GMT). No. of bitstreams: 1 2015 - Ana Cristina Miranda Senna Gouv?a.pdf: 13924664 bytes, checksum: 4ac5eb037aa43029293669dc68b06137 (MD5) Previous issue date: 2015-06-18 Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPQ In recent years, the great interest for natural, healthy foods and that may bring the proposal to act as an aid in reducing the risk of chronic diseases has driven the scientific community to identify and quantify their active ingredients. Anthocyanins, water-soluble pigments present in plant foods, have bioactive effects that are related to its antioxidant power. Therefore, several scientific papers have reported the importance of their performance in reducing the risk of developing diseases such as cardiovascular, immune system dysfunction, cancer and its progression. For their analysis identification and quantification, it is necessary to purchase analytical standards. Because of the wide variety of substituents in structure, the challenge is to find commercially available reference standards of these various substances. This work aims to study and select matrices that can be used as sources for obtaining anthocyanin standards. In this context, the idolated compound obtained from these natural sources may allow the quantification in more precise manner, of the existing concentration of such substances in food that are in the natural or processed form. Studies were carried out for improvement of chromatographic, extraction, and isolation and purification steps, enabling the work conduction. Chromatographic analysis were performed using High Performance Liquid Chromatography (HPLC / DAD) and Ultra Performance Liquid Chromatography (UPLC) coupled to an accurate mass detector Q-TOF (ESI +). In the development of chromatographic method, the run time was reduced by using column with particles lower than 3?m. Three extraction procedures were tested in order to make this step faster. Different methodologies for isolation and purification of substances were evaluated, by using the Rheodyne? channels selector valve, a glass column (C18 phase) and Sep-Pak C18 cartridges and Oasis? MCX Cation-Exchange SPE (ion exchange). After the improvement and development steps, 43 matrices were studied as potential sources to be used as anthocyanin standards. The compounds were separated by HPLC and characterized by using four parameters: retention time, relationship between data of the UV-Vism?x spectrophotometric region and the molecule structures; their molecular ions accurate masses and fragments; and fragmentation routes differences. Thus, these parameters have allowed the identification of substances in the matrices that after isolated could be used as analytical standards, with high purity, thus allowing the identification and quantification of anthocyanins in chromatographic analysis. In the present work, it was possible to validate the developed and implemented chromatographic method, which was applied for the study and characterization of anthocyanin unknown profiles of two fruits of the Myrtaceae family Nos ?ltimos anos, o grande interesse por alimentos naturais, saud?veis e que possam trazer consigo a proposta de atuar como coadjuvantes na redu??o do risco de doen?as cr?nicas tem impulsionado o meio cient?fico a identificar e quantificar os seus princ?pios ativos. As antocianinas, pigmentos hidrossol?veis presentes em alimentos de origem vegetal, apresentam efeitos bioativos que est?o relacionados ao seu poder antioxidante. Sendo assim, v?rios trabalhos cient?ficos v?m relatando a import?ncia do seu desempenho na redu??o do risco de desenvolvimento de doen?as como as cardiovasculares, do sistema imunol?gico, c?ncer e sua progress?o. Para sua an?lise de identifica??o e quantifica??o, h? necessidade de se adquirir padr?es anal?ticos. Devido ? grande diversidade de substituintes em sua estrutura, o desafio est? em encontrar dispon?veis comercialmente padr?es de refer?ncia dessas diversas subst?ncias. Este trabalho teve como objetivo estudar e selecionar matrizes que possam servir de fontes para obten??o de padr?es antoci?nicos. Neste contexto, a obten??o destes padr?es a partir de fontes naturais poder? viabilizar a determina??o, de forma mais precisa, das concentra??es existentes dessas subst?ncias em alimentos que estejam na forma natural ou processados. Para condu??o do trabalho foram realizados estudos para melhoria das etapas cromatogr?fica, de extra??o, e de isolamento e purifica??o das antocianinas. Nas an?lises cromatogr?ficas foram utilizados os sistemas de Cromatografia L?quida de Alta Efici?ncia (CLAE/DAD) e Cromatografia de Ultra Efici?ncia (CLUE) acoplado ao detetor de massas acuradas Q-TOF (ESI+). No desenvolvimento do m?todo cromatogr?fico, reduziu-se o tempo da corrida com uso de coluna com part?cula inferior a 3?m. Foram testados tr?s procedimentos de extra??o da subst?ncia na matriz, visando proporcionar rapidez ? t?cnica. Para o isolamento e purifica??o das subst?ncias, foram utilizados tr?s tipos de t?cnicas: uso de uma v?lvula seletora de canais Rheodyne de seis canais; coluna aberta de vidro (fase C18) e cartuchos Sep Pak C18 e Oasis? MCX Cation-Exchange SPE (troca i?nica). Ap?s as etapas de melhoria e desenvolvimento, foram estudadas ao todo 43 matrizes como potenciais fontes provedoras de padr?es de antocianinas. As subst?ncias foram separadas por CLAE e caracterizadas com aux?lio conjunto de quatro par?metros: tempo de reten??o, dados da rela??o espectrofotom?trica na regi?o do UV-Vism?x com as estruturas da mol?cula, massas acuradas dos seus ?ons moleculares e fragmentos e, distin??o das rotas de fragmenta??es. Assim sendo, esses par?metros permitiram a identifica??o nas matrizes de subst?ncias que ap?s isoladas puderam ser utilizadas como padr?es, com alto grau de pureza, permitindo assim a identifica??o e quantifica??o de antocianinas nas an?lises cromatogr?ficas. No presente trabalho foi poss?vel ainda realizar a valida??o do m?todo de an?lise cromatogr?fica desenvolvido e implantado, o qual foi aplicado para o estudo e caracteriza??o dos perfis antoci?nicos at? ent?o desconhecidos de dois frutos da fam?lia das Myrtaceae.

Confined water in the slit mesopores of the mineral tobermorite provides an excellent model system for analyzing the dynamic properties of water confined in cement-like materials. In this work, we use broadband dielectric spectroscopy (BDS) to analyze the dynamic of water entrapped in this crystalline material. Two samples, one natural and one synthetic, were analyzed, and despite their similar structure, the motion of confined water in their zeolitic cavity displays considerably different behavior. The water dynamics splits into two different behaviors depending on the chemical nature of the otherwise identical structural environment: water molecules located in areas where the primary building units are SiO4 relax slowly compared to water molecules located in cavities built with both AlO4 and SiO4. Compared to water confined in regular porous systems, water restricted in tobermorite is slower, indicating that the mesopore structure induces high disorder in the water structure. A comparison with water confined in the C–S–H gel is also discussed in this work. The strong dynamical changes in water due to the presence of aluminum might have important implications in the chemical transport of ions within hydrated calcium silicates, a process that governs the leaching and chemical degradation of cement., Support from the Basque government through the Nanoiker Project (grant no. IE14-393) under the ETORTEK Program is acknowledged. S.C. acknowledges SAIOTEK S-PE13IV001 and the Spanish Ministry of Education, project MAT2012-31088. H.M. acknowledges the Juan de la Cierva Contract from the Spanish Ministerio de Industria y Competitividad.

Ultrathin two-dimensional (2D) nanosheets (NSs) possess extraordinary properties that are attractive for both fundamental studies and technological devices. Solution-based bottom-up methods are emerging as promising routes to produce free-standing NSs, but the synthesis of colloidal NSs with well-defined size and shape has remained a major challenge. In this work, we report a novel method that yields 2 nm thick colloidal Cu2-xS NSs with well-defined shape (triangular or hexagonal) and size (100 nm to 3 mu m). The key feature of our approach is the use of a synergistic interaction between halides (Br or Cl) and copper-thiolate metal-organic frameworks to create a template that imposes 2D constraints on the Cu-catalyzed C-S thermolysis, resulting in nucleation and growth of colloidal 2D Cu2-xS NSs. Moreover, the NS composition can be postsynthetically tailored by exploiting topotactic cation exchange reactions. This is illustrated by converting the Cu2-xS NSs into ZnS and CdS NSs while preserving their size and shape. The method presented here thus holds great promise as a route to solution-processable compositionally diverse ultrathin colloidal NSs with well-defined shape and size.

A transferable force field for the PbSe-CdSe solid system using the partially charged rigid ion model has been successfully developed and was used to study the cation exchange in PbSe-CdSe heteronanocrystals [A. O. Yalcin et al., "Atomic resolution monitoring of cation exchange in CdSe-PbSe heteronanocrystals during epitaxial solid-solid-vapor growth," Nano Lett. 14, 3661-3667 (2014)]. In this work, we extend this force field by including another two important binary semiconductors, PbS and CdS, and provide detailed information on the validation of this force field. The parameterization combines Bader charge analysis, empirical fitting, and ab initio energy surface fitting. When compared with experimental data and density functional theory calculations, it is shown that a wide range of physical properties of bulk PbS, PbSe, CdS, CdSe, and their mixed phases can be accurately reproduced using this force field. The choice of functional forms and parameterization strategy is demonstrated to be rational and effective. This transferable force field can be used in various studies on II-VI and IV-VI semiconductor materials consisting of CdS, CdSe, PbS, and PbSe. Here, we demonstrate the applicability of the force field model by molecular dynamics simulations whereby transformations are initiated by cation exchange. (C) 2014 AIP Publishing LLC.

Nanoparticle lattices and surfaces The challenge of resolving the details of the surfaces or assemblies of colloidal semiconductor nanoparticles can be overcome if several characterization methods are used (see the Perspective by Boles and Talapin). Boneschanscher et al. examined honeycomb superlattices of lead selenide nanocrystals formed by the bonding of crystal faces using several methods, including high-resolution electron microscopy and tomography. The structure had octahedral symmetry with the nanocrystals distorted through “necking”: the expansion of the contact points between the nanocrystals. Zherebetskyy et al. used a combination of theoretical calculations and spectroscopic methods to study the surface layer of lead sulfide nanocrystals synthesized in water. In addition to the oleic acid groups that capped the nanocrystals, hydroxyl groups were present as well. Science , this issue p. 1377 , p. 1380 ; see also p. 1340

A relatively rapid, economic and robust procedure is described for the alpha-radiometric analysis of natural waters. The analysis is performed by alpha-spectroscopy after pre-concentration and separation of uranium by cation-exchange (Chelex-100) and finally its electrodeposition on stainless steel discs. The method has been successfully applied to 100 ml samples of natural waters (e.g. ground- and seawaters) resulting in high-quality spectra for measurement times less than 34 h. In addition, a main advantage of the procedure (particularly for routine measurements) is that there is no consumption of organic solvents and multiple recycling/reuse of the resin is possible. © 2010 Elsevier Ltd. All rights reserved. 45 8 966 968 Cited By :21

地球環境問題のひとつとして「環境の酸性化」が挙げられるが, 積雪地帯における酸性雪は, 蓄積した酸性物質を一度に放出するアシッドショックなる現象により, 河川・湖沼やそこに存在する生態系に大きな影響を及ぼす恐れがある。本研究では種々の地形特性を考慮できる多層型メッシュモデルに土壌内化学反応過程モデルを結合し, 森林流域河川における酸性雪が河川に与える影響を分析できる手法を開発する。, In Japan we have acid rain and snow recently, and various influences on ecosystem are appeared.One of them is the fact that river water acidifles in the snowmelting season. The phenomenon is called acid shock. In addition to that, the pH value of river water changes regulary everyday through a year.The purpose of study is to develop the model which predict acidification of rivers in forest basin area caused by acid rain and snow. The model is applied to the Myouri River at the northern part of Lake Biwa.

The concentration of trivalent americium and samarium in aqueous samples has been determined by means of alpha-radiometry and UV-Vis photometry, respectively, after chemical separation and pre-concentration of the elements by cation-exchange using Chelex-100 resin. Method calibration was performed using americium (241Am) and samarium standard solutions and resulted in a high chemical recovery for cation-exchange. Regarding, the effect of physicochemical parameters (e.g. pH, salinity, competitive cations and colloidal species) on the separation recovery of the trivalent elements from aqueous solutions by cation-exchange has also been investigated. The investigation was performed to evaluate the applicability of cation-exchange as separation and pre-concentration method prior to the quantitative analysis of trivalent f-elements in water samples, and has shown that the method could be successfully applied to waters with relatively low dissolved solid content. © 2013 Akadémiai Kiadó, Budapest, Hungary. 299 1 721 724

Photoelectron spectroscopic measurements have been performed, with synchrotron radiation on PbSe/CdSe heteronanocrystals that initially consist of core-shell structures. The study of the chemical states of the main elements in the nanocrystals shows a reproducible and progressive change in the valence-band and core-level spectra under photon irradiation, whatever the core and shell sizes are. Such chemical modifications are explained in light of transmission electron microscopy observations and reveal a phase transformation of the nanocrystals: The core-shell nanocrystals undergo a morphological change toward a Janus structure with the formation of semidetached PbSe and CdSe clusters. Photoelectron spectroscopy gives new insight into the reorganization of the ligands anchored at the surface of the nanocrystals and the modification of the electronic structure of these heteronanocrystals.