A hybrid Si@FeSiy/SiOx anode structure for high performance lithium-ion batteries via ammonia-assisted one-pot synthesis

Synthesised via planetary ball-milling of Si and Fe powders in an ammonia (NH3) environment, a hybrid Si@FeSiy/SiOx structure shows exceptional electrochemical properties for lithium-ion battery anodes, exhibiting a high initial capacity of 1150 mA h g−1 and a retention capacity of 880 mA h g−1 after 150 cycles at 100 mA g−1; and a capacity of 560 mA h g−1 at 4000 mA g−1. These are considerably high for carbon-free micro-/submicro-Si-based anodes. NH3 gradually turns into N2 and H2 during the synthesis, which facilitates the formation of highly conductive FeSiy (y = 1, 2) phases, whereas such phases were not formed in an Ar atmosphere. Milling for 20–40 h leads to partial decomposition of NH3 in the atmosphere, and a hybrid structure of a Si core of mixed nanocrystalline and amorphous Si domains, shelled by a relatively thick SiOx layer with embedded FeSi nanocrystallites. Milling for 60–100 h results in full decomposition of NH3 and a hybrid structure of a much-refined Si-rich core surrounded by a mantle of a relatively low level of SiOx and a higher level of FeSi2. The formation mechanisms of the SiOx and FeSiy phases are explored. The latter structure offers an optimum combination of the high capacity of a nanostructural Si core, relatively high electric conductivity of the FeSiy phase and high structural stability of a SiOx shell accommodating the volume change for high performance electrodes. The synthesis method is new and indispensable for the large-scale production of high-performance Si-based anode materials

Silicon and Carbon-Based Anode Materials for Lithium and Sodium-Ion Rechargeable Batteries

This thesis is focused on the Si-based anode materials for lithium-ion batteries (LIBs) as well as biomass-derived carbons for LIBs and sodium-ion batteries (NIBs). In our first attempt we investigated the effect of the support growth substrate as well as of aluminum coating layers on the electrochemical performance of the silicon nanowires. We observed improved cycling performance in the Si nanowires coated with 3 and 8 wt.% aluminum, as compared to the uncoated nanowires. The aluminum shell helps maintain the mechanical integrity of the coated parts of the nanowires, thereby slowing down capacity degradation. A solid electrolyte interphase (SEI) that was stable under the beam in a transmission electron microscope (TEM) was observed only on bare parts of a nanowire. Nanowires grown on a TiN underlayer not only demonstrated a higher specific capacity during cycling but also significantly improved coulombic efficiency with respect to nanowires grown directly on stainless steel, which is attributed mainly to a difference in size distribution. In our second attempt, we conformally coated the Si nanowires with TiO2 using atomic layer deposition (ALD), in which it showed a remarkable performance improvement. The coulombic efficiency is increased to ~99%, among the highest ever reported for Si nanowires, as compared to 95% for the baseline uncoated samples. The capacity retention after 100 cycles for the nanocomposite was twice as high as that of the baseline at 0.1 C (60% vs. 30%), and more than three times higher at 5 C (34% vs. 10%). We also demonstrated that the microstructure of the coatings was critically important towards achieving this effect. Titanium dioxide coatings with an as-deposited anatase structure are nowhere near as effective as amorphous ones, the latter proving much more resistant to delamination from the Si nanowires core. We used TEM to demonstrate that upon lithiation the amorphous coating developed a highly dispersed nanostructure comprised of crystalline LiTiO2 and a secondary amorphous phase. In our third attempt, we explored the use of ALD of TiO2, TiN and Al2O3 on the inner, the outer, or both surfaces of hollow Si nanotubes (SiNTs) for improving their cycling performance. We demonstrated that all three materials enhanced the cycling performance, with optimum performance being achieved for SiNTs conformally coated on both sides with 1.5 nm of Li active TiO2. Substantial improvements wer achieved in the cycling capacity retention (1700 mAh/g vs. 1287 mAh/g for the uncoated baseline, after 200 cycles at 0.2C), and steady-state coulombic efficiency (~100% vs. 97-98%). TEM and other analytical techniques were employed to provide new insight into the lithiation cycling-induced failure mechanisms that turned out to be intimately linked to the microstructure and the location of these layers. In our last attempt, we showed that Banana peel pseudographite (BPPG) offers superb dual functionality for NIBs and LIBs anodes. The materials possessed low surface areas (19 - 217 m2 g-1) and a relatively high electrode packing density (0.75 g cm-3 vs. ~ 1 g cm-3 for graphite). Tested against Na, BPPG delivered a gravimetric capacity of 355 mAh/g after 10 cycles at 50 mA/g. A nearly flat ~ 200 mAh/g plateau that is below 0.1 V, and a minimal charge/discharge voltage hysteresis, made BPPG a direct electrochemical analogue to graphite but with Na. A charge capacity of 221 mAh/g at 500 m/Ag was degraded by 7% after 600 cycles, while a capacity of 336 mAh/g at 100 mA/g was degraded by 11% after 300 cycles, in both cases with ~ 100% cycling coulombic efficiency. For LIB applications BPPG offered a gravimetric capacity of 1090 mAh/g at 50 mA/g. The reason that BPPG worked so well for both NIBs and LIBs was that it uniquely contained three essential features: a) dilated intergraphene spacing for Na intercalation at low voltages; b) highly accessible near-surface nanopores for Li metal filling at low voltages; and c) substantial defect content in the graphene planes for Li adsorption at higher voltages. The < 0.1 V charge storage mechanism was fundamentally different for Na versus for Li. A combination of XRD and XPS demonstrates highly reversible Na intercalation rather than metal underpotential deposition. By contrast, the same analysis proved the presence of metallic Li in the pores, with intercalation being much less pronounced

Systematic comparison of the functional physico-chemical characteristics and biocidal activity of microbial derived biosurfactants on blood-derived and breast cancer cells

Hypothesis The cytotoxicity of biosurfactants on cell membranes may be influenced by composition of their hydrophilic head and hydrophobic tails. It is hypothesised that they form mixed micelles which exert a detergent-like effect that disrupts the plasma membrane. The functional physico-chemical and biocidal characteristics of four biosurfactants were concurrently investigated to determine which of their structural characteristics may be tuned for greater efficacy. Experiments Rhamnolipid-95, rhamnolipid-90, surfactin and sophorolipid were characterised using FTIR, LC-MS, HPLC, surface tension and critical micelle concentration. Their biocidal activity against HEK 293, MCF-7 and THP-1 cell lines were investigated by MTT assay, using doxorubicin as cytotoxic control. Growth curves were established for all cell lines using trypan blue (TB) and MTT assays, corresponding doubling time (DT) and growth rate were obtained and compared. Findings HEK 293 cell-line had the highest growth rate amongst the three cell lines. For TB assay, growth of HEK 293 > THP-1 and for MTT, HEK 293 > MCF-7 while the DT was in the order of THP-1 > MCF-7 > HEK 293. Sophorolipid showed anti-proliferative activity comparable to doxorubicin on THP-1 > MCF-7 > HEK 293. THP-1 showed high sensitivity to sophorolipid with IC50 of 10.50, 25.58 and 6.78 (μg/ml) after 24, 48 and 72 hr respectively. However, sophorolipid was cytotoxic from 24-72 hr on HEK 293 cell lines with IC50 of 21.53, 40.57 and 27.53 μg/ml respectively. Although, doxorubicin showed higher anti-proliferative activity than all biosurfactants, it had poorer selectivity index for the same time durations compared to the biosurfactants. This indicates that biosurfactants were more effective for slowing the growth of the tested cancer cell lines and hence may be potential candidates for use in human cancer therapy. Physico-chemical characteristics of the biosurfactants suggest that their mechanism of action may be due to activity on the cell membrane

Presenting a Consciousness Empowerment Model through Interactions between Architecture and Thought Technology

The main objective of this study is to provide a consciousness empowerment model through interactions between architecture and technology of thought and also investigating the effectiveness of this overlap and communication in improving the current situation of society via designating an educational and social counseling complex, we were about to answer the question that weather interaction, deployment and implementation of concepts and technology of thought components and architecture can be effective or not. By acting and manifestation of these criteria and concepts in which they are a measure to address some of the problems and concerns of most people in the community and also contribute to the success of the community, arise here and can significantly make improvements. To this end, we described dimensions for measuring the performance of concepts and components, and accordingly hypotheses were proposed. Then, according to the results of the analysis, inferences about the relations studied in the research were carried out and conclusions were drawn about these relations and presented in two models and conceptual model

DIETARY TRAITS OF LATE MIOCENE HIPPARIONS FROM MARAGHEH REVEALED THROUGH DENTAL WEAR

This study investigates the palaeoecology of fossil perissodactyls (equids) from the late Miocene of Maragheh, northwestern Iran. We used dental micro- and mesowear techniques to draw robust inferences about fossil equid paleoenvironment. Mesowear and microwear analyses were applied to the upper molars of three species of hipparionine horses. For this purpose, we investigated samples from three fossiliferous localities: Rohanion, Azim, and Cizdahaban. Six fossil specimens were analyzed for enamel meso- and microwear and results were compared to an extensive database of extant ungulates. Results indicated overlap of the Maragheh hipparions with the dietary signal of extant grazers and grass-dominated mixed feeders. This is consistent with the supposed vegetational habitat proposed by previous mesowear studies. The different species of hipparions from Maragheh had similar diets and were consuming a mixture of plants but with a preference for grasses.&nbsp; These results are consistent with paleoenvironmental reconstructions of the late Miocene dominated by open grassland areas among more wooded settings

Azo dye removal via surfactant-assisted polyvinylidene fluoride membrane

Background: Recently, concerns have been raised regarding the environmental and public health safety of azo dyes, the most widely used synthetic dyes. The membrane technique has been introduced as one of the efficient methods for dye removal treatments. Polyvinylidene fluoride (PVDF) membrane manipulated by surfactants was studied for removal of the azo dye, carmoisine. Methods: PVDF membrane was prepared via non-solvent-induced phase separation (NIPS) and used to remove the azo dye, carmoisine. Three nonionic surfactants including Tween 20, Tween 60, and Tween 80 were used individually as additives in casting solutions to improve PVDF membrane properties. Results: Fourier-transform infrared spectroscopy (FTIR) demonstrated the presence of functional groups of carbonyl (C=O) and hydroxyl (OH), assigned to Tween molecules, in the membrane chemical structure. All Tween species caused a decrease in the surface hydrophobicity of PVDF membranes illustrated by the reduced contact angles. Each Tween at a 2% concentration in the dope solution led to an increase in the pore-size of PVDF membranes, which was estimated by scanning electron microscopy (SEM). However, this impact was reversed at Tween concentrations of 4%. Membranes were assessed for dye removal efficiency and permeate flux in a cross-flow system. Permeability of PVDF membranes improved (~78%) with adding Tween 80 at a concentration of 2%. Tween 60 at a 2% concentration resulted in a ~45% increase in dye removal efficiency of PVDF membranes. And, atomic force microscopy (AFM) showed that Tween 60 increased membrane surface roughness. Conclusion: Surfactant-mediated changes in the surface properties of PVDF membrane improved dye removal efficacy. Keywords: Polyvinylidene fluoride, Coloring agents, Azo compounds, Surface-active agent

Cormohipparion cappadocium, a new species from the Late Miocene of Yeniyaylacık, Türkiye, and the emergence of western Eurasian Hipparion bioprovinciality

We studied the Vallesian records from Türkiye and Iran, and uncovered a diverse record of Cormohipparion species from Yeniyaylacık and Sinap, Türkiye, and their apparent descendant, Hipparion gettyi from Maragheh, Iran. This prompted us to examine the early evolutionary diversification, biogeography and paleoclimatology of western Eurasian hipparions. Our study also included the early hipparion records from Austria, Germany and the Iberian Peninsula. Whereas the Vienna Basin, Austria, has the oldest recorded occurrence of Hippotherium sp. at 11.4-11.0 Ma, our investigation revealed that the most primitive Old World hipparions belonged to the North American genus Cormohipparion. We integrated the data on crania, dentitions, 3rd metacarpals and 3rd metatarsals to further evaluate the systematics of Vallesian hipparions (11.2-9.6 Ma). Sinap, Türkiye, has the most primitive Cormohipparion in Eurasia, Co. sinapensis, but based on postcranial anatomy, we found that also Co. kecigibi is a second Cormohipparion species of Sinap's early Vallesian. The locality of Yeniyaylacık, Türkiye, dated ca. 9.1 Ma, has the latest occurrence of Eurasian Cormohipparion, Co. cappadocium. Our analyses also revealed that the genus Hipparion sensu stricto was probably directly derived from Subparatethyan (including Türkiye) Cormohipparion, with the most primitive taxa being Hipparion gettyi and Hipparion prostylum. Hipparion gettyi first occurred at Maragheh, Iran, ca. 9.0 Ma at the end of MN 10. Hipparion sensu stricto includes H. gettyi, H. prostylum, H. dietrichi and H. hippidiodus and had a range that extended from France through Greece and Türkiye to China

Sleep Quality among Shift-working Nurses in the Hospitals of Rafsanjan City, Iran, in 2018

Background: Nursing deals with shift working in different hours of the day and night. Sleep disorders due to disturbed sleep-wake cycle and the circadian cycle lead to physical and mental disintegration of the person. This study was conducted to examine the sleep quality of shift-working nurses in the hospitals of Rafsanjan. Methods: This descriptive and analytical cross-sectional study was carried out on 180 shift-working nurses in educational hospitals of Rafsanjan during April and May 2018. In order to collect data, the Pittsburgh Sleep Quality Questionnaire was used. Data analysis was done using t-test، Chi-Square، Fisher Exact test and through SPSS 18. Results: The sleep quality of 56 shift-working nurses (31.10%) was optimal, while 124 nurses (68.90%) had inappropriate sleep quality. There was a statistically significant relationship between sleep quality and job satisfaction among nurses (P=0.036), so that, nurses who had job satisfaction had also optimal sleep quality. In terms of sleep quality dimensions, delayed sleep was the most prominent problem of nurses. Conclusion: Research findings showed improper sleep quality of shift-working nurses in hospitals of Rafsanjan, which probably affects their job satisfaction, as well as their mental and general health. This can cause serious disorders in professional performance, quality of nursing services, personal life and other roles

Lutetian Schizaster Fauna (Echinoidea, Spatangoida) from Sargaz Area, South of Kerman, Iran

The spatangoid genus Schizaster Agassiz is recorded, for the first time, from the Lutetian (Middle Eocene) deposits of Sargaz area, south of Kerman, Iran. The Lutetian sediments of Sargaz region contain a rich and divers echinoid fauna represented by Cidaridae, Conoclypeidae, Echinolampadidae, Toxopneustidae, Phymosomatidae and Schizasteridae. Schizasteroid echinoids are an important component of this fauna. Five Schizasteroid echinoids assigned to genus Schizaster are described and illustrated in the present paper. The Schizaster species are Schizaster ambulacrum, S. archiaci, S. globulus, S. lucidus and S. spado. The Schizaster specimens occur in association with a rich nummulitids and alveolinids  fauna, and macro-invertebrates consisting of bivalves and gastropods, which suggest a Lutetian age for the sediment. Associated micro-macro fauna also indicate a warm and shallow water environment was prevailed during the deposition of the sediments

Optical properties of ZnO deposited by atomic layer deposition (ALD) on Si nanowires

International audienceIn this work, we report proof-of-concept results on the synthesis of Si core/ ZnO shell nanowires (SiNWs/ZnO) by combining nanosphere lithography (NSL), metal assisted chemical etching (MACE) and atomic layer deposition (ALD). The structural properties of the SiNWs/ZnO nanostructures prepared were investigated by X-ray diffraction, Raman spectroscopy, scanning and transmission electron microscopies. The X-ray diffraction analysis revealed that all samples have a hexagonal wurtzite structure. The grain sizes are found to be in the range of 7-14 nm. The optical properties of the samples were investigated using reflectance and photoluminescence spectroscopy. The study of photoluminescence (PL) spectra of SiNWs/ZnO samples showed the domination of defect emission bands, pointing to deviations of the stoichiometry of the prepared 3D ZnO nanostructures. Reduction of the PL intensity of the SiNWs/ZnO with the increase of SiNWs etching time was observed, depicting an advanced light scattering with the increase of the nanowire length. These results open up new prospects for the design of electronic and sensing devices