Effects of temperature and sodium carboxylate additives on mineralization of calcium oxalate in silica gel systems

The effects of temperature and multifunctional sodium carboxylate additives on the phase composition and morphology of calcium oxalate (CaOxa) crystals grown in silica gel system were systematically investigated using scanning electron microscopy (SEM), powder X-ray diffraction (XRD), and Fourier-transform infrared spectra (FT-IR). The sodium carboxylates investigated include: monocarboxylate sodium acetate (NaAc), disodium tartrate (Na2tart), trisodium citrate (Na3cit), and the disodium salt of ethylenediaminetetraacetic acid (Na2edta). The temperature range was from 7°C to 67°C. The crystallization temperature affects the phase compositions, the growth rate, and the morphology of CaOxa. First, the logarithm of the percentage of calcium oxalate dihydrate (COD) formed at a certain temperature (T) is proportional to the reciprocal of temperature (1/T). Second, the weight of CaOxa crystals decreases as decreasing the temperature. At a given temperature, the ability of the sodium carboxylates to induce COD follows the order: Na2edta Na3cit Na2tart NaAc. Third, the multicarboxylates can decrease the surface area of calcium oxalate monohydrate (COM). It makes the edges and tips of COM crystals blunt and oval. All the three changes, an increase of the content of COD, a decrease of the weight of CaOxa crystals, and a decrease of the surface area of COM crystals, can inhibit the formation of CaOxa stones. These results support the clinical use of citrates and may be helpful in elucidating the mechanisms of the formation of CaOxa calculus. Keywords calcium oxalate - sodium carboxylate - gel - urinary calculi - crystallization - biomineralization

High-performance of sodium carboxylate-derived materials for electrochemical energy storage

Four types of sustainable sodium carboxylate- derived materials are investigated as novel electrodes with high performance for lithium-ion batteries. Benefiting from the porous morphology provided by their intermolecular in- teractions, increasing capacity, excellent cycle stability and superior rate performance are observed for the sodium car- boxylate-derived materials. The sodium oxalate （SO） electro- des displayed an increasing discharging capacity at a current density of 50 mA g-1 with maximum values of 242.9 mA h g-1 for SO-631 and 373.9 mA h g-1 for SO-541 during the 100th cycle. In addition, the SO-541, SC-541 （sodium citrate）, ST- 541 （sodium tartrate） and SP-541 （sodium pyromellitate） electrode materials displayed high initial capacities of 619.6-392.3, 403.7 and 278.1 mA h g-1, respectively, with capacity retentions of 179%, 148%, 173% and 108%, respectively, after 200 cycles at 50 mA g-1. Even at a high current density of 2,000 mA g-1, the capacities remain 157.6, 131.3, 146.6 and 137.0mAhg-1, respectively. With these superior electro- chemical properties, the sodium carboxylate-derived materials could be considered as promising organic electrode materials for large-scale sustainable lithium-ion batteries.

Novel Vesicular Aqueous Two-Phase Systems

The interesting phenopmena of two aqueous phases coexisting in dilute aqueous solutions of sodium undecenoate-dodecyltrimethylammo brodride ndxture and sodium laurate-dodecyltrimethylammonium brondde mixture were investigated. Vesicles existing in both phases were shown by TEM images. The vesicles are dispersed in lower phase and flocculated in upper phase. Multilamellar structure of vesicles was found in the upper phase of sodium laurate-dodecyltrimethylammonium bromide system.

Adsorption of Toluene on Film Membranes of Chitosan/Nа-CMC

The sorption properties of films on bases of chitosan and sodium carboxyl methylcellulose (Na-CMC) with toluene have been checked. The sorption rate, sorption thermodynamics and isothermal properties of toluene molecules in chitosan/Na-CMC films are analyzed by adsorption-calorimetric method. Thus, it was found that toluene is adsorbed on the chitosan/Na-CMC film by the same patterns of sorption of aromatic compounds, due to the process of penetration of toluene molecules into the network of chitosan macromolecules and this is preceded by the absorption process by the surface of the chitosan/Na-CMC film.

A general synthetic strategy to monolayer graphene

The emergence and establishment of new techniques for material fabrication are of fundamental importance in the development of materials science. Thus, we herein report a general synthetic strategy for the preparation of monolayer graphene. This novel synthetic method is based on the direct solid-state pyrolytic conversion of a sodium carboxylate, such as sodium gluconate or sodium citrate, into monolayer graphene in the presence of Na2CO3. In addition, gram-scale quantities of the graphene product can be readily prepared in several minutes. Analysis using Raman spectroscopy and atomic force microscopy clearly demonstrates that the pyrolytic graphene is composed of a monolayer with an average thickness of - 0.50 nm. Thus, the present pyrolytic conversion can overcome the issue of the low monolayer contents （i.e., 1 wt.%-12 wt.%） obtained using exfoliation methods in addition to the low yields of chemical vapor deposition methods. We expect that this novel technique may be suitable for application in the preparation of monolayer graphene materials for batteries, supercapacitors, catalysts, and sensors.