The combined action of Mg2+ and Cl− ions in cement pastes

In order to study the phenomenon of seawater attack on hydrated cement components, we focused our interest on the combined action of Mg²⁺ and Cl⁻ ions on hydrated cement pastes. Thus, cement pastes were prepared from portland cement and its mixture with 30% pozzolan (Santorin Earth). These pastes were cured in baths of varied concentrations of Mg²⁺ and Cl⁻ ions and stored in 18 ± 2°C. The hydration phenomena were studied in these cement pastes, by XRD and SEM.     

Preparation and evaluation of α-Al2O3 supported lithium ion sieve membranes for Li+ extraction

Spinel lithium manganese oxide ion-sieves have been considered the most promising adsorbents to extract Li⁺ from brines and sea water. Here, we report a lithium ion-sieve which was successfully loaded onto tubular α-Al₂O₃ ceramic substrates by dipping crystallization and post-calcination method. The lithium manganese oxide Li₄Mn₅O₁₂ was first synthesized onto tubular α-Al₂O₃ ceramic substrates as the ion-sieve precursor (i.e. L-AA), and the corresponding lithium ion-sieve (i.e. H-AA) was obtained after acid pickling. The chemical and morphological properties of the ion-sieve were confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Both L-AA and H-AA showed characteristic peaks of α-Al₂O₃ and cubic phase Li₄Mn₅O₁₂, and the peaks representing cubic phase could still exist after pickling. The lithium manganese oxide Li₄Mn₅O₁₂ could be uniformly loaded not only on the surface of α-Al₂O₃ substrates but also inside the pores. Moreover, we found that the equilibrium adsorption capacity of H-AA was 22.9 mg·g⁻¹. After 12 h adsorption, the adsorption balance was reached. After 5 cycles of adsorption, the adsorption capacity of H-AA was 60.88% of the initial adsorption capacity. The process of H-AA adsorption for Li⁺ correlated with pseudo-second order kinetic model and Langmuir model. Adsorption thermodynamic parameters regarding enthalpy (∆ H), Gibbs free energy (∆ G) and entropy (∆ S) were calculated. For the dynamic adsorption–desorption process of H-AA, the H-AA exhibited excellent adsorption performance to Li⁺ with the Li⁺ dynamic adsorption capacity of 9.74 mg·g⁻¹ and the Mn²⁺ dissolution loss rate of 0.99%. After 3 dynamic adsorption–desorption cycles, 80% of the initial dynamic adsorption capacity was still kept.     

Recent progress in LiF materials for safe lithium metal anode of rechargeable batteries: Is LiF the key to commercializing Li metal batteries?

The lithium metal battery has attracted considerable attention as the ultimate lithium secondary battery for high energy density. However, safety issues and battery performance deterioration due to the growth of lithium dendrites have hampered the practical use of lithium metal batteries. Recently, lithium fluoride has been considered as a lithium metal protective layer to solve this problem. In this review, firstly, the results of the studies on dendrites and SEI that have been carried out to date are reviewed. Secondly, the results of studies on lithium fluoride are divided into additive, artificial SEI, and other methods and the possibilities of their practical use are discussed. Finally, the significance and limitations of the lithium fluoride studies are summarized, and general conclusions and prospects for recommended research directions to accelerate the commercialization of lithium metal batteries are presented.     

Can the performance of graphene nanosheets for lithium storage in Li-ion batteries be predicted?

Graphene nanosheets (GNS) were prepared from graphitic oxide (GO) in two different ways: (a) thermal exfoliation at different temperatures; and (b) wet chemistry, using aqueous N(2)H(4) and KBH(4) as reducing agents. Irrespective of the synthetic method used, the materials exhibited a high irreversible capacity and strong polarization in their charge curves, when used in a Li-ion battery. The GNS synthesized with N(2)H(4) exhibited the best performance. Thus, at 149 mA g(-1) the average specific capacity delivered was ca. 600 mA h g(-1) after 100 cycles. On the other hand, the worst performance, irrespective of rate, was that of GNS synthesized with KBH(4) and the thermal GNS obtained at 800 °C. The physical and chemical analyses allowed various parameters to be derived for correlation with the electrochemical properties. Unfortunately, no clear-cut correlation was apparent. A comparison with reported data revealed that no correlation appears to exist with physical and chemical properties that allows a simple strategy for tailoring an effective graphene anode to be designed.     

Oxidative competition between aliphatic and aromatic CH bonds in the N2O–Fe-ZSM-5 system

The peculiar electrophilic behaviour of active oxygen formed over Fe-ZSM-5 zeolites upon nitrous oxide decomposition has been investigated in toluene oxidation. Fe-ZSM-5 catalysts have been produced by hydrothermal and post-synthetic techniques, with particular attention given to preparation by chemical vapour deposition of anhydrous FeCl₃ into H-ZSM-5. Higher yields of hydroxylated product are possible over Fe-zeolites prepared by hydrothermal synthesis, with para-cresol being the predominant oxygenate formed, though the formation of tars and polycondensed aromatic hydrocarbons retards catalytic activity over time. Oxidation of para-xylene, isopropylbenzene, benzaldehyde, chlorobenzene and phenol demonstrate that the oxidative competition between aliphatic and aromatic CH bonds is influenced considerably by the steric and electronic nature of the substituent groups.     

Electrochemical cycling behaviour of lithium carbonate (Li2CO3) pre-treated graphite anodes – SEI formation and graphite damage mechanisms

Graphite electrode surfaces were treated using a simple process of sedimentation in aqueous solutions containing 0.5 and 1.0 wt.% Li₂CO₃ with particle sizes of ∼1–2 μm. During the first cycle of voltammetry tests (vs. Li/Li⁺), the graphite surface was subjected to electrochemical degradation as a result of fracture and removal of near-surface graphite particles. Surface degradation was accompanied by a 0.4% strain in the graphite lattice as determined by in situ Raman spectroscopy. Pre-treated electrodes experienced a capacity drop of 3% in the first cycle, compared to a 40% drop observed in case of untreated graphite electrodes. After testing for 100 cycles, a capacity of 0.54 mAh cm⁻² was recorded for the pre-treated electrodes as opposed to a significant drop to 0.11 mAh cm⁻² for the untreated graphite. Cross-sectional HR-TEM indicated that the SEI formed on the pre-treated electrodes primarily consisted of Li₂CO₃ crystals of 14.6 ± 6.9 nm in size distributed within an amorphous matrix. The results suggested that the Li₂CO₃ enriched SEI formed on the pre-treated electrodes reduced the intensity of solvent co-intercalation induced surface damage. It is proposed that the Li₂CO₃ enriched SEI facilitated Li⁺ diffusion and hence improved the capacity retention during long-term cycling.     

Effect of Mg2+ and fluorine on the network and highly efficient photoluminescence of Eu3+ ion in MgF2–BaO–B2O3 glasses

The glass structure and photoluminescence of new oxyfluoride glasses with the composition of xMgF₂–(66.7−2x/3)BaO–(33.3−x/3)B₂O₃ (x = 10-50 mol%) were investigated in this work. The structure of the glasses was investigated by magic-angle spinning NMR, XAS, and Raman scattering spectroscopies. It was revealed that the glasses are mainly composed of BO₃ units with a disconnected borate network consisting mainly of ortho- and pyro-borate units, and ortho-borate increases with the addition of MgF₂. The fluorine atoms are surrounded by Mg²⁺ and Ba²⁺ ions. The photoluminescence of Eu³⁺-doped samples were investigated. It was indicated that asymmetry of the Eu³⁺ site increased with the addition of MgF₂. The photoluminescence quantum yield (η) of the glasses are very high and increased with MgF₂ addition; red photoluminescence is observed with η = 82% for 10MgF₂ and η = 98% for 50MgF₂ for excitation at 393 nm.     

Is Photoprotection of PSII One of the Key Mechanisms for Drought Tolerance in Maize?

Drought is one of the most important abiotic stress factors limiting maize production worldwide. The objective of this study was to investigate whether photoprotection of PSII was associated with the degree of drought tolerance and yield in three maize hybrids (30Y87, 31R88, P3939). To do this, three maize hybrids were subjected to three cycles of drought, and we measured the activities of photosystem II (PSII) and photosystem I (PSI). In a second field experiment, three maize hybrids were subjected to drought by withholding irrigation, and plant water status, yield and yield attributes were measured. Drought stress decreased leaf water potential (Ψ_L) in three maize hybrids, and this reduction was more pronounced in hybrid P3939 (−40%) compared to that of 30Y87 (−30%). Yield and yield attributes of three maize hybrids were adversely affected by drought. The number of kernels and 100-kernel weight was the highest in maize hybrid 30Y87 (−56%, −6%), whereas these were lowest in hybrid P3939 (−88%, −23%). Drought stress reduced the quantum yield of PSII [Y(II)], photochemical quenching (qP), electron transport rate through PSII [ETR(II)] and NPQ, except in P3939. Among the components of NPQ, drought increased the Y(NPQ) with concomitant decrease in Y(NO) only in P3939, whereas Y(NO) increased in drought-stressed plants of hybrid 30Y87 and 31R88. However, an increase in cyclic electron flow (CEF) around PSI and Y(NPQ) in P3939 might have protected the photosynthetic machinery but it did not translate in yield. However, drought-stressed plants of 30Y87 might have sufficiently downregulated PSII to match the energy consumption in downstream biochemical processes. Thus, changes in PSII and PSI activity and development of NPQ through CEF are physiological mechanisms to protect the photosynthetic apparatus, but an appropriate balance between these physiological processes is required, without which plant productivity may decline.     

Is LRP2 Involved in Leptin Transport over the Blood-Brain Barrier and Development of Obesity?

The mechanisms underlying the transport of leptin into the brain are still largely unclear. While the leptin receptor has been implicated in the transport process, recent evidence has suggested an additional role of LRP2 (megalin). To evaluate the function of LRP2 for leptin transport across the blood-brain barrier (BBB), we developed a novel leptin-luciferase fusion protein (pLG), which stimulated leptin signaling and was transported in an in vitro BBB model based on porcine endothelial cells. The LRP inhibitor RAP did not affect leptin transport, arguing against a role of LRP2. In line with this, the selective deletion of LRP2 in brain endothelial cells and epithelial cells of the choroid plexus did not influence bodyweight, body composition, food intake, or energy expenditure of mice. These findings suggest that LRP2 at the BBB is not involved in the transport of leptin into the brain, nor in the development of obesity as has previously been described.     

Comparative study of lithium ion conductors in the system Li1+xAlxA2−xIV (PO4)3 with AIV=Ti or Ge and 0≤x≤0·7 for use as Li+ sensitive membranes

Preparations and physico-chemical characterizations of NASICON-type compounds in the system Li_1+xAl_xA_2−x^IV(PO₄)₃ (A^IV=Ti or Ge) are described. Ceramics have been fabricated by sol-gel and co-grinding processes for use as ionosensitive membrane for Li⁺ selective electrodes. The structural and electrical characteristics of the pellets have been examined. Solid solutions are obtained with Al/Ti and Al/Ge substitutions in the range 0≤x≤0·6. A minimum of the rhombohedral c parameter appears for x about 0·1 for both solutions. The grain ionic conductivity has been characterized only in the case of Ge-based compounds. It is related to the carrier concentration and the structural properties of the NASICON covalent skeleton. The results confirm that the Ti-based framework is more calibrated to Li⁺ migration than the Ge-based one. A grain conductivity of 10⁻³ S cm⁻¹ is obtained at 25°C in the case of Li_1·3Al_0·3Ti_1·7(PO₄)₃. A total conductivity of about 6×10⁻⁵ S cm⁻¹ is measured on sintered pellets because of grain boundary effects. The use of such ceramics in ISE devices has shown that the most confined unit cell (i.e. in Ge-based materials) is more appropriate for selectivity effect, although it is less conductive.©     

Involvement of Ca2+ Signaling in the Synergistic Effects between Muscarinic Receptor Antagonists and β2-Adrenoceptor Agonists in Airway Smooth Muscle

Long-acting muscarinic antagonists (LAMAs) and short-acting β₂-adrenoceptor agonists (SABAs) play important roles in remedy for COPD. To propel a translational research for development of bronchodilator therapy, synergistic effects between SABAs with LAMAs were examined focused on Ca²⁺ signaling using simultaneous records of isometric tension and F340/F380 in fura-2-loaded tracheal smooth muscle. Glycopyrronium (3 nM), a LAMA, modestly reduced methacholine (1 μM)-induced contraction. When procaterol, salbutamol and SABAs were applied in the presence of glycopyrronium, relaxant effects of these SABAs are markedly enhanced, and percent inhibition of tension was much greater than the sum of those for each agent and those expected from the BI theory. In contrast, percent inhibition of F340/F380 was not greater than those values. Bisindolylmaleimide, an inhibitor of protein kinase C (PKC), significantly increased the relaxant effect of LAMA without reducing F340/F380. Iberiotoxin, an inhibitor of large-conductance Ca²⁺-activated K⁺ (K_Ca) channels, significantly suppressed the effects of these combined agents with reducing F340/F380. In conclusion, combination of SABAs with LAMAs synergistically enhances inhibition of muscarinic contraction via decreasing both Ca²⁺ sensitization mediated by PKC and Ca²⁺ dynamics mediated by K_Ca channels. PKC and K_Ca channels may be molecular targets for cross talk between β₂-adrenoceptors and muscarinic receptors.     

Measurement and Correlation of Solubility for Propylene in 2-Butanol+Water Solutions

In order to obtain solubility data of propylene in 2-butanol+water solutions, gas-liquid equilibrium (GLE) experiment was carried out at 303.15-333.15 K, 0.3-1.2MPa with static equilibrium still. Original mass ratios of 2-butanol to water are 1 : 0, 9 : 1, 8 : 2 and 7 : 3, respectively. The equilibrium data are correlated with an empirical correlation. The average relative deviation (ARD) between experimental and calculated values is 2.15%, and the maximum relative deviation (MRD) is less than 5%.     

Collaborations between Israel and Germany in Chemistry and the Other Sciences – a Sign of Normalization?

The scientific collaboration between Israel and Germany was not initiated, as commonly believed, by the Max Planck Society or by German scientists who wanted to revive collaboration with their former Jewish colleagues. Rather, it was initiated in the mid-1950s by two Israeli scientists from the Weizmann Institute and a German scientist at the time at CERN in violation of the widely accepted cultural boycott by Israel against Germany. The initiators succeeded in procuring political support; large-scale collaboration between the Weizmann Institute, German universities, and the Max Planck Society was developed. In the aftermath of the Second World War, German science suffered from the Nazi expulsion of Jewish scientists and partial international isolation; the collaboration with Israel enabled young German scientists to overcome this isolation and benefit from stimulating Israeli research environments. In times of economic hardship, the collaboration helped Israeli science materially, provided contacts to chemical industry, and strengthened the cooperation between Israeli and European science. The collaboration was built, in part, on postwar myths created by German scientists and the Max Planck Society about their former anti-Nazi attitudes. Despite the difficult beginnings and some hidden political agendas, the collaboration developed very successfully. Germany became Israel’s second most important partner in the scientific field, after the USA. Today, normalcy prevails in many – though not all – of the Israeli-German collaborative projects; the past is not forgotten, but science is in the fore.     

Reduction of the 1,4,5,8-tetrasila-1,4,5,8-tetrahydroanthracene derivative with lithium metal. Isolation and characterization of the tetralithium salt of a tetraanion,and observation of an Si–H⋯Li+ interaction

Treatment of 2,3,6,7-tetrakis(dimethylsilyl)-1,1,4,4,5,5,8,8-octamethyl-1,4,5,8-tetrasila-1,4,5,8-tetrahydroanthracene (1) with lithium metal in diethyl ether yields dark red crystals of the tetralithium salt of the tetraanion, 2, in which the two tetrasilylethylene units are subjected to a two-electron reduction. The molecular structure of 2, determined by X-ray crystallography, is discussed in comparison with that of the neutral molecule 1. Evidence for the interaction between Si–H and the Li⁺ ion of 2, in both solid state and solution, is also given.     

Is there any contradiction between the stress and energy failure criteria in micromechanical tests? Part III. Experimental observation of crack propagation in the microbond test

A direct observation of crack propagation in the microbond test was carried out for five different fiber/polymer matrix systems. This technique appeared to be a very effective tool for interface characterization. Experimental plots of the force required for further crack propagation as a function of debond length were analyzed using both energy-based and stress-based models of debonding. The fracture mechanics analysis was used to construct families of crack resistance or R-curves which showed the variation of energy release rate, G, with the debond length, and included the effect of interfacial friction in debonded regions. For the first time, analogs of the R-curves were created within the scope of the stress-based model to present the local shear stress near the crack tip, τ, as a function of crack length. In both models, the behavior of the interfacial parameter (G or τ) strongly depends on the assumed value of the interfacial frictional stress (τ_f). However, for each matrix/fiber system there exists such a τ_f value for which the investigated parameter is nearly constant over the whole region of stable crack propagation (70–90% of the embedded length). Moreover, these best-fit τ_f values for each specimen appeared to be practically the same for both energy-based and stress-based approaches. Thus, both interfacial toughness, G _ic, and local interfacial shear strength, τ_d, adequately characterize the strength of a fiber/matrix interface. Extrapolation of R-curves and their analogs to zero crack length allows measurement of the interfacial parameters with good accuracy.     

Crystal structure and microwave dielectric properties of Li2Mg0.6− xCoxZn0.4SiO4 ceramic for LTCC applications

In this work, Li₂Mg_0.6−xCo_xZn_0.4SiO₄ ceramics (x = 0–0.4) added with 3 wt% Li₂O–B₂O₃–Bi₂O₃–SiO₂ (LBBS) glass were synthesised using the solid-state reaction method. The effects of substituting Co²⁺ for Mg²⁺in Li₂Mg_0.6−xCo_xZn_0.4SiO₄ ceramics on crystal structure, microstructure, densification, crystallisation and microwave dielectric properties were investigated. X-ray diffraction patterns showed that monoclinic Li₂MgSiO₄, monoclinic Li₂ZnSiO₄ and orthorhombic Li₂CoSiO₄ formed finite solid solution in Li₂Mg_0.6−xCo_xZn_0.4SiO₄ ceramics. Clear grain boundaries were observed via scanning electron microscopy. The substitution of Co²⁺ for Mg²⁺ increased grain size, densification, crystallinity degree and dielectric constant; it also reduced the dielectric loss of the ceramics to a certain extent. The absolute values of τ_f were positively related to the crystallinity degree. Li₂Mg_0.55Co_0.05Zn_0.4SiO₄ ceramic added with 3 wt% LBBS and sintered at 900 °C exhibited considerable microwave dielectric properties of ε_r = 5.8, Q × f = 47,518 GHz and τ_f = −74.8 ppm/°C. Therefore, the ceramic is considered a candidate low-temperature co-fired ceramic material for substrate and filter applications.     

Immuno-Expression of Endoglin and Smooth Muscle Actin in the Vessels of Brain Metastases. Is There a Rational for Anti-Angiogenic Therapy?

Despite ongoing clinical trials, the efficacy of anti-angiogenic drugs for the treatment of brain metastases (BM) is still questionable. The lower response rate to anti-angiogenic therapy in the presence of BM than in metastatic disease involving other sites suggests that BM may be insensitive to these drugs, although the biological reasons underlining this phenomenon are still to be clarified. With the aim of assessing whether the targets of anti-angiogenic therapies are actually present in BM, in the present study, we analyzed the microvessel density (MVD), a measure of neo-angiogenesis, and the vascular phenotype (mature vs. immature) in the tumor tissue of a series of BM derived from different primary tumors. By using immunohistochemistry against endoglin, a specific marker for newly formed vessels, we found that neo-angiogenesis widely varies in BM depending on the site of the primary tumor, as well as on its histotype. According to our results, BM from lung cancer displayed the highest MVD counts, while those from renal carcinoma had the lowest. Then, among BM from lung cancer, those from large cell and adenocarcinoma histotypes had significantly higher MVD counts than those originating from squamous cell carcinoma (p = 0.0043; p = 0.0063). Of note, MVD counts were inversely correlated with the maturation index of the endoglin-stained vessels, reflected by the coverage of smooth muscle actin (SMA) positive pericytes (r = −0.693; p < 0.0001). Accordingly, all the endoglin-positive vessels in BM from pulmonary squamous cell carcinoma and renal carcinoma, displayed a mature phenotype, while vessels with an immature phenotype were found in highly vascularized BM from pulmonary large cell and adenocarcinoma. The low MVD and mature phenotype observed in BM from some primary tumors may account for their low sensitivity to anti-angiogenic therapies. Although our findings need to be validated in correlative studies with a clinical response, this should be taken into account in therapeutic protocols in order to avoid the adverse effects of useless therapies.     

Amyloid cross-seeding between Aβ and hIAPP in relation to the pathogenesis of Alzheimer and type 2 diabetes

Amyloid cross-seeding of different amyloid proteins is considered as a highly possible mechanism for exacerbating the transmissible pathogenesis of protein misfolding disease(PMDs) and for explaining a molecular link between different PMDs, including Alzheimer disease(AD) and type 2 diabetes(T2D),AD and Parkinson disease(PD), and AD and prion disease.Among them, AD and T2D are the most prevalent PMDs, affecting millions of people globally, while Aβ and hIAPP are the causative peptides responsible for AD and T2D, respectively.Increasing clinical and epidemiological evidences lead to a hypothesis that the cross-seeding of Aβ and hIAPP is more biologically responsible for a pathological link between AD and T2D.In this review, we particularly focus on(i) the most recent and important findings of amyloid cross-seeding between Aβ and h IAPP from in vitro, in vivo, and in silico studies,(ii) a mechanistic role of structural compatibility and sequence similarity of amyloid proteins(beyond Aβ and hIAPP)in amyloid cross-seeding, and(iii) several current challenges and future research directions in this lessstudied field.Review of amyloid cross-seeding hopefully provides some mechanistic understanding of amyloidogenesis and inspires more efforts for the better design of next-generation drugs/strategies to treat different PMDs simultaneously.     

Synthesis and electrochemical performance of LiVOPO4–Li3V2(PO4)3 cathode materials for lithium ion batteries

Lithium-ion batteries (LIBs) present the advantages of long cycle life, high voltage, and energy density and are widely made in the field of energy storage. LiVOPO₄ (LVOP), a cathode material used in LIBs, has a high conceptual capacity of 159 mAh g⁻¹ and high operating voltage of 3.9 V. However, its low electrical conductivity and cycle performance limit its commercial applications. According to the X-ray diffraction results, orthogonal crystal LVOP and monoclinic crystal Li₃V₂(PO₄)₃ (LVP) coexisted in the synthesised composite material. The transmission electron microscopy results also indicated that the LVOP and LVP phases coexist, which were coated by carbon layer of about 2.5 nm. The discharge of LVOP–LVP composite material initially was 143.2 mAh g⁻¹, and that after 120 cycles was 132.2 mAh g⁻¹ (at 0.1 C and 3–4.5 V). Thus, the electronic conductivity and first discharge specific capacity of the material enhanced due to the introduction of fast ion conductor LVP into LVOP. Electrochemical performance improved because the introduction of LVP led to an increase in Li⁺ pervasion channels in the original material and the acceleration of the Li⁺ transmission speed.