Renewable Surface Research Articles

Research of the value of linear distortion of renewable surface of part during rotary processing of bulky items without dismantling unit

The loading and unloading units and grinding mills of raw devices have internal cone type or pipe screw perceive load of incoming and outgoing material. The main part of the support assembly is a pin. Mounting seats for the pipe screws cone have traces of deformation and work hardening, while they themselves have wear of pins and deformation of the inner and outer cylindrical working surface. In the mill body, there are constantly acting dynamic forces causing vibration, which are transmitted to the stud and inner accelerating elements. Under the influence of stress and vibration, the housing spigot is in the stress-compressed state and stretched vertically and horizontally. As a result, the insertion element is deformed and weakened in the fixture. A moving element appears in the gap leading to the fact that it drops lfeedstock and under the influence of variable loads it is destroyed, as well as the seating surfaces of the insert pin member.

Surface Freshwater Limitation Explains Worst Rice Production Anomaly in India in 2002

India is the second-most populous country and the second-most important producer of rice of the world. Most Indian rice production depends on monsoon timing and dynamics. In 2002, the lowest monsoon precipitation of the last 130+ years was observed. It coincided with the worst rice production anomaly recorded by FAOSTAT from 1961 to 2014. In that year, freshwater limitation was blamed as responsible for the yield losses in the southeastern coastal regions. Given the important implication for local food security and international market stability, we here investigate the specific mechanisms behind the effects of this extreme meteorological drought on rice yield at the national and regional levels. To this purpose, we integrate output from the hydrological model, surface, and satellite observations for the different rice cropping cycles into state-of-the-art and novel climate indicators. In particular, we adopt the standardized precipitation evapotranspiration index (SPEI) as an indicator of drought due to the local surface water balance anomalies (i.e., precipitation and evapotranspiration). We propose a new indicator of the renewable surface freshwater availability due to non-local sources, i.e., the standardized river discharge index (SDI) based on the anomalies of modelled river discharge data. We compare these indicators to the soil moisture observations retrieved from satellites. We link all diagnostics to the recorded yields at the national and regional level, quantifying the long-term correlations and the best match of the 2002 anomaly. Our findings highlight the need for integrating non-local surface freshwater dynamics with local rainfall variability to determine the soil moisture conditions in rice fields for yields assessment, modeling, and forecasting.

Lead-doped carbon ceramic electrode as a renewable surface composite electrode for the preparation of lead dioxide film and detection of l-tyrosine

Lead-doped carbon ceramic electrode as a new type of renewable composite electrode was prepared by mixing the lead powder with electrode matrix before gelation. Pb on the electrode surface was then converted to lead dioxide by the potential scanning of the composite electrode in 0.1 M NaOH solution in the range of − 0.3 to 0.7 V versus SCE. The composition and morphology of the electrodes were studied by energy dispersive X-ray spectrometry, scanning electron microscopy, and atomic force microscopy techniques. Cyclic voltammetry and chronoamperometry techniques were also used to study the electrocatalytic activity of the modified electrode toward the oxidation of the l-tyrosine. The best results were obtained at a working potential of 0.45 V (vs. SCE) in 0.1 M NaOH solution. The sensor exhibited a good linear response in the range of 5–1458 µM with a coefficient of determination of 0.9963. The detection limit was 0.77 µM, and sensitivity was 37.4 μA mM−1. In addition, the modified electrode showed high stability and interference-free response for to detection of the l-tyrosine.

The Sonogel-Carbon-PEDOT Material: An Innovative Bulk Material for Sensor Devices

The synthesis of a new bulk material based on silicon oxide and poly-(3,4-ethylenedioxythiophene) (PEDOT), the Sonogel-Carbon-PEDOT material, is carried out. The main purpose is to obtain a bare conducting material, aided by statistical experimental design, able to be used as transducer for electrochemical devices. This new material tries also to solve out the degradation and fouling drawbacks related to PEDOT-based layer devices by simply polishing its surface in a gently way. The resulting Sonogel-Carbon-PEDOT material shows excellent electrochemical properties, renewable surface and stability by using simple, low cost, and versatile synthesis method. As far as we are concerned, this is the first time that this kind of bulk material is reported. The resulting material was characterized by different techniques: SEM, EDS and Raman spectroscopy. Sonogel-Carbon-PEDOT was also electrochemically characterized for the assessment of the electrochemical performance of the resulting sensor device. Ascorbic acid was selected as reference analyte, obtaining good sensitivity and limit of detection: 319.8 μA mM-1cm-2 and 6.42 μM, respectively, in the concentration range 0.01–3.45 mM. Furthermore, repeatability and reproducibility studies (RSD<3%), were also very satisfactory. Finally, the Sonogel-Carbon-PEDOT sensor was successfully applied to the determination of ascorbic acid in a pharmaceutical formulation and biological samples, obtaining good recovery percentage (95–105%).

Outer-tubes Falling Film Evaporator with Well-Mixed Surface Renewal

A falling film evaporator with a liquid flowing laminarly outside vertical cylindrical tubes was studied by a mathematical modeling in order to describe the performance of the system and the results are later used for a design of a falling film evaporator. In this study a mathematical model was developed from mass and energy as well as momentum transfer processes in an evaporation of a sugar solution. The equations were solved by using a numerical technique known as implicit method. This model yields the prediction of velocity, temperature and concentration profiles of solution as well as rate of mass evaporation and energy required in this process. Evaporation limitation was disclosed to be based on water mass transfer across the liquid thin film. Renewable surface was proposed to enhance the evaporation by adding a collector for liquid mixing before further evaporation. Adding only one collector at the half height of the evaporation tube could increase water evaporation rate by 1.3 and 2.1 % in case of the liquid perfect mixing, respectively.

GENTLE ACTIVATION OF POLYMINERAL SORBENT AND ITS INFLUENCE ON CLEANING PROCESS OF OIL-CONTAINING MEDIA FROM IMPURITY INGREDIENTS

An attempt to evaluate the effect of gentle activation of the surface of polymineral sorbent – blue clay with oxalic acid (Kdis = 5.6∙10-2) and sodium carbonate was carried out. The chemical structure of the initial and activated materials was established by the X-ray phase analysis. The prospect of their use for the sorption extraction of impurity ingredients from oil-containing media was revealed. An important rock-forming mineral in a composition of polymineral sorbent is montmorillonite. It was found that 45 mass% of the powder material has a particle size of 0.3-2.5 μm (quartz, cristoballite), 21% of the particles have a size of 5-10 μm and a small part (≤ 9%) is more than 10 μm. As a result of gentle activation of the sorbent with a 6% solution of oxalic acid, a clearer crystallized surface forms on which the effect of increasing the total pore size (100 nm - 2 μm) is observed. Such activated material is the meso- (20-500 Ǻ) type and macroporous type (&gt; 500 Ǻ). The atomic composition of the renewed surface indicates the partial destruction of kaolinite during acid activation with an additional effect on impurity hydromica and a balancing increase in the mass fraction of quartz and saponite fractions (scaly particle form, 1-3 μm). The data of IR spectroscopic studies confirm the consistency of the judgments. Sequential activation with a solution of alkaline earth metals and sodium carbonate ensures the formation of tortuous pores and the production of disparate and relatively shallow (no more than 5 μm) particles in comparison with the original (globules up to 50 μm are encountered). The observed texture is a loosened land material of a complex chemical composition with the inclusion of natural grains of quartz, crystals (montmorillonite), fibrous structures and individual flakes. When 1% by weight of a polymineral sorbent based on montmorillonite and SiO2 was introduced into linseed oil, it was found that its treatment with 6% solutions of oxalic and succinic acid promotes an increase in the degree of purification from fatty acids to 40% and from peroxide compounds to 40%, then as gentle acid-alkaline activation of the sorbent provides the production of an oil-containing product with an even lower (by 5%) concentration of fatty acids.Forcitation:Nagornov R.S., Razgovorov P.B., Lepilova A.M., Stroganova Yu.I., Smirnov P.R., Kochetkov S.P. Gentle activation of polymineral sorbent and its influence on cleaning process of oil-containing media from impurity ingredients. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 8. P. 53-59.

Electrochemical reduction of Bicarbonate to Formate with Silver Nanoparticles and Silver Nanoclusters supported on Multiwalled Carbon Nanotubes

In this work, we report heterogeneous catalysis of bicarbonate reduction to formate (FA) using silver nanoparticles (Ag NP) and silver nanoclusters (Ag NC) supported on multi-wall carbon nanotubes (MWCNT). FA detection was performed by substrate generation/tip collection (SG/TC) mode of scanning electrochemical microscopy (SECM) using Pt UME in 100mM HCO3− at pH 8. The Ag NP and Ag NC showed high carbonate reduction current, and similar activity as massive gold electrode targets them as alternative catalysts for FA production. Prior to bicarbonate reduction, the electrochemical activity of Ag NP and Ag NC was evaluated using carbon fiber ultra microelectrodes (UME), these carbon UME were fabricated and characterized for use in SCEM mapping; carbon UME provided an excellent feedback response and are dispensable electrodes with renewable surfaces. Also, a carbon UME enables the fabrication of an enzymatic sensor which was designed for NAD+ (Nicotine amide dinucleotide) dependent formate dehydrogenase immobilization. The enzymatic reaction coupled with the redox mediator 2,2V-Azino- bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) allowed a sensitive FA detection. The production of FA on silver particles and the FA detection methods presented in this work will be the target of further investigation for energy storage molecules.

Stratigraphic framework for the plume mode of mantle convection and the analysis of interregional unconformities on geological maps

Mantle convection is a fundamental planetary process. Its plate mode is established and expressed by plate tectonics. Its plume mode also is established and expressed by interregional geological patterns. We developed both an event-based stratigraphic framework to illustrate the surface effects predicted by the plume model of Griffiths et al. (1989) and Griffiths and Campbell (1990) and a methodology to analyze continent-scale geological maps based on unconformities and hiatuses. The surface expression of ascending plumes lasts for tens-of-millions-of-years and rates vary over a few million years. As the plume ascends, its surface expression narrows, but increases in amplitude, leaving distinct geological and stratigraphic patterns in the geologic record, not only above the plume-head center, but also above its margins and in distal regions a few thousands-of-kilometers from the center. To visualize these patterns, we constructed sequential geological maps, chronostratigraphic sections, and hiatus diagrams. Dome-uplift with erosion (Şengör, 2001) and the flood basalts (Duncan and Richards, 1991; Ernst and Buchan, 2001a) are diagnostic starting points for plume-stratigraphic analyses. Mechanical collapse of the dome results in narrow rifting (Burke and Dewey, 1973), drainage-network reorganization (Cox, 1989), and flood-basalt eruption. In the marginal region, patterns of vertical movement, deformation and surface response are transient and complex. At first, the plume margin is uplifted together with the central region, but then it subsides as the plume ascents farther; With plume-head flattening, the plume margin experiences renewed outward-migrating surface uplift, erosion, broad crustal faulting, and drainage reorganization. Knickpoint migration occurs first inward-directed at ½ the rate of plume ascent and later outward-directed at the rate of asthenospheric flow. Interregional-scale unconformity-bounded stratigraphic successions document the two inversions. The distal regions, which did not experience any plume-related uplift, yield complete sedimentary records of the event; Event-related time gaps (hiatuses) in the sedimentary record increase towards the center, but the event horizon is best preserved in the distal region; it may be recognized by tracing its contacts from the center outwards. We extracted system- and series-hiatuses from interregional geological maps and built hiatus maps as proxies for paleo-dynamic topography and as a basis for comparison with results from numerical models. Interregional-scale geological maps are well suited to visualize plume-related geological records of dynamic topography in continental regions. However, geological records and hiatus information at the resolution of stages will be needed at interregional scales. The plume-stratigraphic framework is event-based, interregional, but not global, with time-dependent amplitudes that are significantly larger than those of global eustatic sea-level fluctuations. Global stratigraphic syntheses require integration of plate- and plume-stratigraphic frameworks before eustatic contributions may be assessed.

Construction of Renewable Superhydrophobic Surfaces via Thermally Induced Phase Separation and Mechanical Peeling

We report a simple preparation method of a renewable superhydrophobic surface by thermally induced phase separation (TIPS) and mechanical peeling. Porous polyvinylidene fluoride (PVDF) membranes with hierarchical structures were prepared by a TIPS process under different cooling conditions, which were confirmed by scanning electron microscopy and mercury intrusion porosimetry. After peeling off the top layer, rough structures with hundreds of nanometers to several microns were obtained. A digital microscopy determines that the surface roughness of peeled PVDF membranes is much higher than that of the original PVDF membrane, which is important to obtain the superhydrophobicity. Water contact angle and sliding angle measurements demonstrate that the peeled membrane surfaces display superhydrophobicity with a high contact angle (152°) and a low sliding angle (7.2°). Moreover, the superhydrophobicity can be easily recovered for many times by a simple mechanical peeling, identical to the original superhydrophobicity. This simple preparation method is low cost, and suitable for large-scale industrialization, which may offer more opportunities for practical applications.

Capacitive antibacterial susceptibility screening test with a simple renewable sensing surface

A simple renewable surface for a rapid antibacterial susceptibility test has been demonstrated. The 3-aminophenylboronic acid (3-APBA) modified electrode bind with cis-diol groups on the cell wall of both gram positive and gram negative bacteria. The detection of antibacterial susceptibility response by a capacitive system can be done within a short time, 2.5h for the whole process, with good repeatability of the electrode's preparation. An acid solution, could break the bonding between 3-APBA and the bacteria, which were then easily removed by the fluid flow, renewing the sensing surface for the next test. This modified electrode can be reused up to 35 times. This sensor is useful for testing the susceptibility of bacteria to antibacterial agents that affect their cell wall. Results from the capacitive sensor corresponded well with the antimicrobial information in the literature and to the morphology of the treated bacteria revealed by scanning electron microscopy. Antimicrobial susceptibility to natural products could also be easily tested.

NiO nanoparticles electrodeposited on reduced GO–CuO nanocomposite bulk modified CCE as a sensitive glucose sensor

A novel enzymeless glucose sensor based on nickel oxide (NiO) nanoparticles electrodeposited on reduced graphene oxide-copper oxide nanocomposite bulk modified carbon ceramic electrode (rGO-CuO/CCE) was reported. The prepared NiO/rGO-CuO/CCE was characterised by scanning electron microscopy, energy-dispersive X-ray spectroscopy, atomic-force microscopy, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry techniques. Electrocatalytic performance of the NiO/rGO-CuO/CCE was investigated in details for the electro-oxidation of glucose using cyclic voltammetry and amperometry techniques. The developed sensor responds efficiently to glucose over the concentration range 5-920 μM with the detection limit 2.63 μM and sensitivity 5980 μA mM -1 cm -2 . According to EIS studies, ternary presence of rGO, CuO and NiO nanoparticles increased the electron transfer performance and sensitivity of NiO/rGO-CuO/CCE to glucose. The prepared sensor was applied for the determination of glucose in human serum samples with satisfactory results. Owing to renewable and polishable surface, high sensitivity, reproducible responses and long-term stability, the developed sensor could be used in clinical applications.

Water limits to closing yield gaps

Agricultural intensification is often seen as a suitable approach to meet the growing demand for agricultural products and improve food security. It typically entails the use of fertilizers, new cultivars, irrigation, and other modern technology. In regions of the world affected by seasonal or chronic water scarcity, yield gap closure is strongly dependent on irrigation (blue water). Global yield gap assessments have often ignored whether the water required to close the yield gap is locally available. Here we perform a gridded global analysis (10km resolution) of the blue water consumption that is needed annually to close the yield gap worldwide and evaluate the associated pressure on renewable freshwater resources. We find that, to close the yield gap, human appropriation of freshwater resources for irrigation would have to increase at least by 146%. Most study countries would experience at least a doubling in blue water requirement, with 71% of the additional blue water being required by only four crops – maize, rice, soybeans, and wheat. Further, in some countries (e.g., Algeria, Morocco, Syria, Tunisia, and Yemen) the total volume of blue water required for yield gap closure would exceed sustainable levels of freshwater consumption (i.e., 40% of total renewable surface and groundwater resources).

Groundwater–surface water interactions in Canada

Canada is a water-rich country. Its rivers and lakes comprise 7% of the global annually renewable surface fresh water supply (Rivera 2014). Although it is very difficult to quantify available groun...

Kinetic Regularities of Lead Dioxide Electrocrystallization

Lead dioxide is a promising anodic material owing to corrosive resistivity, low cost and high electrocatalytic activity. Lead dioxide is extensively employed in electroplating, hydrometallurgy, processes of electrosynthesis of strong oxidative agents, organic and inorganic compounds, in reactions of the electrochemical combustion of various organic pollutants (1–3). Establishing of kinetic regularities of the crystallization process and control of its parameters is very important, because determines basic properties of the resulting materials. In the present work we examine early stages of electrocrystallization of PbO2 from methanesulfonate/nitrate electrolytes. Electrodeposition regularities of lead dioxide both in nitrate and methanesulfonate electrolytes were studied on Pt disk electrode by steady-state voltammetry, chronoamperometry. Voltammetry measurements were carried out in a standard temperature-controlled three-electrode cell. All potentials were recorded and reported vs. Ag / AgCl / KCl (sat.). Current transients for PbO2 deposition on Pt disk electrode were obtained for investigation of initial stages lead dioxide electrodeposition (Fig.). The type of transient is determined by the electrode potential. At low polarizations (E=1550 mV) the biggest induction period with a further stretched maximum of current is observed. Increasing of an anodic polarization leads to a substantial decreasing of the induction period and to increasing of current maximum. Such type of transients indicates difficulties in initial stages of nucleation and confirms that the process is controlled by the kinetic stage. The electrocrystallization model, proposed by Abyaneh (4), was selected as appropriate for investigation of initial stages of the formation of a new phase of lead dioxide. In the formation of oxide coatings three basic nuclei geometries such as semi-spheroid, cone and cylinder are considered. Depending on the composition of electrolyte may occur either the predominance of one phase over another or ingesting of growing centres of one phase by another. The formation of one phase is noticeably lagged behind the other. The type of lagging phase depends on the deposition conditions: at low polarizations there is a slight predominance of the growth of α-phase of PbO2; at high polarization α-phase becomes stunted, and there is overlap and ingesting of formed α-phase growth centers by β-phase crystals on the surface of the electrode (5). In all cases, the type of nucleation is progressive. However, the preferred form of crystals at 2D nucleation in the case of methanesulfonate electrolyte is the cylinder, and in the nitrate electrolyte the crystal formation occurs in the form of cones, that is in accordance with scanning electron microscopy results. The electrocrystallisation of PbO2 begins with the formation of a monolayer, and only then there is the formation and growth of 3D nuclei, so each consequent layer is formed on the renewed surface (5). The increase of CH3SO3 - ions in the deposition electrolyte leads to significant reduction in the induction period, that indicates the facilitation of initial stages of phase formation of lead dioxide, and also causes a noticeably increase of the deposition current. This effect of changing of kinetic parameters of 2D nucleation of lead dioxide probably will affect the 3D crystallization of the coating and as a consequence the phase composition of the coating. Thus, in the deposit obtained from the nitrate electrolyte the content of β-phase is much higher, than in the case of a coating, obtained from an electrolyte based on methanesulfonic acid. The character and kinetic parameters of 2D nucleation of lead dioxide crystals allows predicting the phase composition of coatings. With the angular velocity growth the induction period significantly changes. Increasing of the angular velosity should promote the growth rate of accumulation of PbO2 in the surface layer and thereby lead to a reduction of time required for the nucleation. In comparison with perchlorate and nitrate electrolytes (6) in methanesulfonate deposition electrolyte the effect of current reducing with increasing of angular velocity of the electrode at low potential is less pronounced probably due to a more significant interaction of Pb(III) intermediate product with the electrode surface.

Electrochemical Studies of Cysteine

Introduction L-Cysteine is an important amino acid because of its role in various biochemical pathways (1). The sulfhydryl functional group gives L-cysteine significant redox characteristics, prompting an investigation of its electrochemical behavior in various media and electrode surfaces. The interaction of protein cysteine residues with Zn2+ (“zinc fingers”) also suggested a voltammetric study of the effect of Zn2+ on L-cysteine electrochemistry. Experimental L-Cysteine was obtained from Sigma-Aldrich. Electrochemical experiments were carried out using a Gamry Interface 1000 potentiostat and Gamry Framework software. Potentials are referenced against a Ag/AgCl reference electrode. Platinum and glassy carbon electrodes were obtained from BASi. Gold electrodes were purchased from eDAQ. Results and Discussion The voltammetric behavior of 5 mM Zn2+ in 0.10 M KNO3 is shown in the figure. Zinc deposition at -1.0 V was not very distinct, and there was no well-defined stripping peak. Addition of equimolar L-cysteine produced a definite stripping peak at -0.8 V, evidently an effect of complexation of Zn2+ by L-cysteine. The L-cysteine voltammetry was also affected by the presence of Zn2+. At platinum and gold with no addition of Zn2+, oxidation of L-cysteine occurred as merged peaks at +0.8 and +1.0 V (2), with no oxidation feature at +0.6 V. Even with Zn2+ added to L-cysteine n solution, an initial positive-going scan gave no +0.6 V peak, and scanning through the zinc reduction/stripping region was necessary to produce the +0.6 V feature on the second sweep to more positive potentials as shown in the figure. The stripping of the zinc layer from the gold surface may produce a renewed gold surface which allows strong adsorption of L-cysteine on gold. In general, L-cysteine is known to interact strongly with gold surfaces (3). References C. K. Mathews, K. E. Van Holde, D. R. Appling, and S. J. Anthony-Cahill, Biochemistry, 4th Edition, Pearson Canada, Toronto, 2013. J. Koryta and J. Pradac, J. Electroanal. Chem., 1968, 17, 185-189. A. J. Tudos, P. J. Vandeberg, and D. C. Johnson, Analytical Chem., 1995, 67, 552-556. Figure 1. Cyclic voltammograms at gold (1 mm diameter) in aqueous 0.10 M KNO3. 100 mV/s. [ Dashed line : 5.0 mM ZnSO4 ] [ Solid line : 5.0 mM ZnSO4 + 5.3 mM L-cysteine ] Figure 1

Small-Angle Neutron Scattering Investigation of Core-Shell Carbon-Coated Silicon Nanoparticles for Lithium-Ion Anodes

Due to their great success for portable electronic devices, lithium-based batteries are becoming increasingly important for powering (hybrid) electric vehicles. Yet, in order to achieve driving ranges comparable to those provided by combustion engines, substantial improvements regarding their energy density are required. Concerning the anode side, most commercial lithium-ion batteries use carbonaceous materials and silicon material seems promising due to its high theoretical specific capacity (up to 3580 mAh.g-1) and its relatively low operational potential. However, the huge volume expansion of silicon alloys upon lithiation (up to 300%) leads to electrical contact loss and pulverization of the material, as well as a continuous consumption of lithium due to the decomposition of the electrolyte on the renewed fresh surface of Si exposed by the cracks of the particles volume expansion. Thus, it leads to poor cycling stability and rapid capacity fading. These effects can be partially counteracted by using nanometer sized Si particles (Si-NPs) that can better sustain the mechanical strains induced by the heterogeneous volume changes. In addition, the particle expansion could be limited by carbon shell coating onto the nanoparticles, which can enhance the electronic conductivity and stabilize the initially formed solid-electrolyte interphase (SEI). In an attempt to combine both approaches, we have synthetized using a laser pyrolysis technique carbon-coated (Si@C-NPs) or non-coated Si nanoparticles (Si-NPs) [1] [2]. As it was shown that both surface state and crystallinity of the Si-NPs govern the electrochemical behavior of the materials [1] [2], both amorphous and crystalline cores were prepared. Transmission electron microscopy (TEM) was performed on native NPs (see figure 2c and d for illustration on crystalline Si NPs) and revealed the core-shell structure. Electrodes with the various NPs samples (see table 1) were processed and tested in coin cell configuration versus lithium foil. The electrochemical behavior was monitored and it was shown that carbon coating leads to improved capacity upon cycling (see figure 1). To characterize the morphology of the various electrodes upon cycling and its impact on performances, we have carried out in-depth microstructural investigation of NPs (shape, size, core-shell structure) using ex situ small-angle neutron scattering (SANS) at the Institut Laue-Langevin (Neutron reactor-Grenoble). The SANS technique is particularly suited to investigate such complex systems, because neutrons are highly sensitive to lithium (by contrast to X-rays) and can provide detailed chemical/microstructural information hardly attainable using TEM on cycled electrodes. Taking advantage of the contrast variation method (i.e. use of specific isotopic mixtures of solvent to selectively match a compound in multicomponent systems) we were able to unravel the effect of carbon coating on the NPS morphology at different (de-)lithiation stages (see figure 2a and b for results on electrodes with crystalline Si NPs). In particular, we show that Si@C NPs exhibit a different mechanism of Li insertion compared to non-coated NPs. This work elucidates the microstructural evolution of NPs used in battery electrodes and therefore helps in designing innovative nanomaterials for high density Si-based anodes.

Trap and release of bisphenol-A, 2-naphthol, and doxepin using a 1-hexadecylamine-copper(II)-amine functionalized indium-tin-oxide electrode

An electrically controlled and renewable hydrophobic surface used to trap and release three test pollutants on an indium-tin-oxide (ITO) electrode is presented. Oxygen plasma was used to maximize the activated hydroxyl groups on the ITO surface, which were reacted with (3-aminopropyl) triethoxysilane (APTES) to create a 3-amino propyl layer. Copper(II) ions were introduced and attached to the terminal amine groups. The amine group from 1-hexadecylamine (HDA), complexed the surface-confined copper(II) ions, which resulted in terminal hexadecyl alkyl groups. The created hydrophobic surface was tested for its ability to adsorb pollutant substances, namely bisphenol-A, 2-naphthol, and doxepin. Desorption was accomplished by reducing copper(II) to copper(0) electrochemically. This led to the weakening of the metal-amine complex and the concomitant detachment of the HDA and trapped species from the ITO surface. Efficient trapping and releasing of bisphenol-A (1ppm) was achieved with around 84% adsorption, 100% desorption (in a time course of less than 30s), and 42-fold enrichment on the concentration. After each adsorption/desorption trial, regeneration of the hydrophobic surface was achieved by reapplication of copper(II) ions and HDA. Five cycles were successfully repeated without any significant deterioration in performance. Similar trap-and-release performance was also attained for 2-naphthol and doxepin.

Оценка возобновляемых водных ресурсов Европейской части России и пространственно-временной анализ их распределения.

Assessment and analysis of the annual, low-water and minimal monthly runoff of the European part of Russia over the past 35 years (till 2011) in comparison with the earlier periods of observation (1945–1977) have been performed. The runoff genesis for different river basins has been studied and the main causes of the current changes of the runoff characteristics have been found. Regional regularities of hydrological/hydro/geological processes have been stated zoning of the territories with emphasis on the river runoff formation features has been carried out. Re-estimation of the renewable (natural) surface and ground water resources over 1970–2010 has been done. Regional estimation and analysis of water resources distribution in the European part of Russia enable to make conclusions on the surface and ground water components of river runoff spatial/temporal dynamics taking into consideration contemporary features of their formation under the non-stationary climate influence. Positive changes of the annual average and especially winter air temperatures in combination with atmospheric precipitation greatly affected the rivers water content and their runoff regime. Climate changes have already caused considerable alterations of the water regime and the water resources formation conditions in a number of major regions.

English

The human cornea requires a smooth, transparent, robust and renewable surface to maintain its key optical and protective functions. The corneal epithelium is maintained by a local population of “stem cells”, which although not truly pluripotent, are capable of self-regeneration by asymmetric division. These cells are located at the limbus - the region where the conjunctiva-covered sclera meets the cornea. The widely accepted “XYZ” hypothesis of corneal epithelial maintenance postulates that limbal stem cells give rise to transient amplifying cells, which migrate and mature in both a centripetal and anterograde fashion towards the corneal surface. Many diseases and injuries to the limbus can cause the loss of this vital reservoir of cells and, due to subsequent surface irregularity and loss of corneal transparency, result in severe visual impairment, including blindness. Indeed, in some regions of the developing world corneal blindness may be more prevalent than cataract blindness. Such corneal blindness was previously irreversible, but over the past 30 years it has been possible to improve or restore vision using limbal “stem cell” transplants. Pioneering techniques required large tissue grafts that could compromise the donor eye, but recent developments allow the harvesting, ex-vivo expansion and transplantation of limbal stem cells from relatively small biopsies. In this review we outline limbal stem cell physiology in health and disease, describe our surgical approach to limbal stem cell deficiency, illustrate results of this intervention in our practice, and consider current and future advances in this arena.

AUTOLOGOUS CORNEAL REPAIR USING IN-VITRO ADULT STEM CELL EXPANSION

The human cornea requires a smooth, transparent, robust and renewable surface to maintain its key optical and protective functions. The corneal epithelium is maintained by a local population of “stem cells”, which although not truly pluripotent, are capable of self-regeneration by asymmetric division. These cells are located at the limbus - the region where the conjunctiva-covered sclera meets the cornea. The widely accepted “XYZ” hypothesis of corneal epithelial maintenance postulates that limbal stem cells give rise to transient amplifying cells, which migrate and mature in both a centripetal and anterograde fashion towards the corneal surface. Many diseases and injuries to the limbus can cause the loss of this vital reservoir of cells and, due to subsequent surface irregularity and loss of corneal transparency, result in severe visual impairment, including blindness. Indeed, in some regions of the developing world corneal blindness may be more prevalent than cataract blindness. Such corneal blindness was previously irreversible, but over the past 30 years it has been possible to improve or restore vision using limbal “stem cell” transplants. Pioneering techniques required large tissue grafts that could compromise the donor eye, but recent developments allow the harvesting, ex-vivo expansion and transplantation of limbal stem cells from relatively small biopsies. In this review we outline limbal stem cell physiology in health and disease, describe our surgical approach to limbal stem cell deficiency, illustrate results of this intervention in our practice, and consider current and future advances in this arena.