Ternay Au@TiO2/α-Fe2O3 Nanocomposite with Nanoring Structure: Synthesis,Characterization and Photocatalytic Activity

Journal of Inorganic and Organometallic Polymers and Materials - In the present study, a modified solvothermal reaction of (hematite) with titanium(IV) butoxide and gold(III) chloride produced...     

Crack arrest in high cycle thermal fatigue crazing

Thermal crazing in high cycle thermal fatigue due to thermal fluctuation in residual heat removal (RHR) system of some nuclear power plants is explained by crack arrest in the depth due to a decreasing stress intensity factor. This is related to high frequencies of thermal loading. An attempt has been made through a parametric study to acquire some knowledge about the loading, knowing the crack depth. For this purpose, analytical as well as finite element simulations of crack propagation in 2D- and 3D-semi-elliptical cracks have been performed. In periodic loading, bounds for the number of cycles to fatigue life are proposed. Moreover, it is shown that in the absence of mean stress, fatigue damage in RHR may be produced in the macroscopic elastic-plastic regime. Finally, it is shown by FE simulations that for a semi-elliptical crack, a small error on stress intensity factor may result in significant error on crack length at high number of cycles, due to error accumulation cycle by cycle. Moreover in this paper is given the reason as to why shielding effect has not been taken into account in the study of crack arrest in RHR.     

Graphene oxide a promising formaldehyde scavenger of phenolic resin-bonded plywood: From elaboration to evaluation

A long-standing manufactured and most frequently used resin is phenol-formaldehyde resin, which has currently reached new horizons by incorporating nano reinforcements, even at lower loadings. Nanostructured materials, particularly graphene, have gained considerable interest in recent years because of their fascinating characteristics. Herein, this study explores for the first time the potential of prepared graphene oxide (GnO) as an effective formaldehyde scavenger in the development of plywood panels containing PF resins. The addition of 1% of GnO to the system resulted in a significant improvements in the mechanical properties by more than 45% in the shear strength (SS), 35% in modulus of elasticity, and 25% in modulus of rupture when compared with the reference panel. While the moisture resistance of panels were found to remarkably enhanced showing an increase in SS by 25% and 37% After 24 h in cold water (20°C) and 12 h of immersion in boiling water, respectively. The results also demonstrated that GnO exhibited exceptional formaldehyde capture efficiency, surpassing 60% reduction compared with the control. This innovative research not only unveils the novel potential of GnO in improving the performance of PF resins but also ushers in a new way of developing eco-friendly wood-based materials.     

A Degron Blocking Strategy Towards Improved CRL4CRBN Recruiting PROTAC Selectivity**

Small molecules inducing protein degradation are important pharmacological tools to interrogate complex biology and are rapidly translating into clinical agents. However, to fully realise the potential of these molecules, selectivity remains a limiting challenge. Herein, we addressed the issue of selectivity in the design of CRL4^CRBN recruiting PROteolysis TArgeting Chimeras (PROTACs). Thalidomide derivatives used to generate CRL4^CRBN recruiting PROTACs have well described intrinsic monovalent degradation profiles by inducing the recruitment of neo-substrates, such as GSPT1, Ikaros and Aiolos. We leveraged structural insights from known CRL4^CRBN neo-substrates to attenuate and indeed remove this monovalent degradation function in well-known CRL4^CRBN molecular glues degraders, namely CC-885 and Pomalidomide. We then applied these design principles on a previously published BRD9 PROTAC (dBRD9-A) and generated an analogue with improved selectivity profile. Finally, we implemented a computational modelling pipeline to show that our degron blocking design does not impact PROTAC-induced ternary complex formation. We believe that the tools and principles presented in this work will be valuable to support the development of targeted protein degradation.     

Formulation and rheology of eco-self-compacting concrete (Eco-SCC)

This article presents the results of an experimental study on the rheology of eco-SCC, formulated on the basis of the modified Chinese method and on the new standard EN206/CN. The studied ecological concretes consist of Portland pozzolana cement, containing large amounts of limestone filler or natural pozzolana, which can replace cement up to 50%. In addition, the compactness of the granular mixture is optimized; therefore, the total amount of the incorporated binder is further reduced in the body of concrete. The study of the rheological behavior of these fluid concretes was carried out in the laboratory, using a coaxial vane-type rheometer. The results showed that both rheological models, i.e. modified Bingham and Herschel–Bulkley, describe satisfactorily the shear-thinning character of the formulations tested. However, the rheological parameters obtained with the modified Bingham model seem to have better correlations with the measurements of the slump test. These same results also indicated that replacing 30% of cement by one of the additions selected for our study, resulted in mixtures with yield stress and plastic viscosities that are within the validity range of SCC. This allowed reducing CO₂ emissions by about 40% for each cubic meter of concrete produced.     

Improved Photocatalytic Activity Using Ternary Au-ZnO/rGO Nanocomposite

In the present study, ternary Au-ZnO/rGO nanocomposite was prepared using a modified polyol protocol. The ternary structure was attained by deposition of both gold nanoparticles (AuNPs) and ZnO NPs on the rGO surface. No surfactants or ligands are used in this chemical process. On the other hand, 1,3-propanediol was used as solvent, reducing agent and surfactant to ensure the formation of NPs and inhibit particles accumulation. The XRD data confirm the successful formation of the three materials and the high crystallinity of the as-prepared sample. Moreover, the XPS measurements confirmed the high purity of the nanocomposite. TEM images show the formation of ternary Au/ZnO/rGO nanostructure. However, Au and ZnO NPs exhibited spherical shape with an average size of 20 nm and homogeneously distribution onto the rGO surface. The ternary Au-ZnO/rGO nanocomposite exhibited optical response in both UV and visible region due to the plasmonic properties of AuNPs. The BET data revealed an increase of the surface area of Au-ZnO/rGO nanocomposite compared to bare ZnO and hybrid Au-ZnO NPs which render it a promising system for high photocatalytic activity. The preliminary photodegradation measurements against MB molecules prove the high performance of the ternary Au-ZnO/rGO nanocomposite to decompose pollutant molecules compared to bare ZnO. The observed photocatalytic activity enhancement could be attributed to the apport given by both plasmonic properties of AuNPs and the high surface area of rGO.

     

Effect of electrolyte additives in improving the cycle and calendar life of graphite/Li1.1[Ni1/3Co1/3Mn1/3]0.9O2 Li-ion cells

Lithium-rich layered metal oxide Li_1.1[Ni_1/3Co_1/3Mn_1/3]_0.9O₂ was investigated as a potential positive electrode material for high-power batteries for hybrid electric vehicle (HEV) applications. In order to evaluate the power and life characteristics of the graphite/Li_1.1[Ni_1/3Co_1/3Mn_1/3]_0.9O₂ cell chemistry, hybrid pulse power characterization (HPPC) and accelerated calendar life tests were conducted on several pouch cells containing electrolytes with and without additives. The data show that the cells containing 0.5 wt% lithium bis(oxalate)borate (LiBOB) or vinyl ethyl carbonate (VEC) additives, or the novel lithium difluoro(oxalato)borate (LiDFOB) additive, have much improved cycle and calendar life performance.     

Crystalline ZnO and ZnO/TiO2 nanoparticles derived from tert-butyl N-(2 mercaptoethyl)carbamatozinc(II) chelate: Electrocatalytic studies for H2 generation in alkaline electrolytes

A newly synthesized zinc(II) complex, namely tert-butyl N-(2 mercaptoethyl)carbamatozinc(II) complex [Zn(Boc-S)₂] (Boc = tert-butyl N-[2-mercaptoethyl]carbamate), has been used as an organozinc precursor for the production of crystalline ZnO and ZnO/TiO₂ nanoparticles. The synthesized complex and the obtained nanomaterials were fully characterized using various spectroscopic and surface analysis techniques. Their surface morphology, chemical purity and stoichiometry have been investigated by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) as well as X-ray fluorescence. The synthesized Zn(II) molecular complex, ZnO and ZnO/TiO₂ nanomaterials have been tested in alkaline aqueous solution (1.0 MNaOH) for the hydrogen evolution reaction (HER) using various electrochemical techniques. The results revealed high HER catalytic performance of ZnO and ZnO/TiO₂ cathode materials, with the latter exhibiting higher catalytic activity recording an exchange current density (j_o) of 0.3 mA cm⁻². This current value, which approaches that of Pt wire (0.5 mA cm⁻²), cross-sectional area ~0.008 cm², is about 11 and 100 times greater than those measured for ZnO alone (0.028 mA cm⁻²) and TiO₂ alone (0.0032 mA cm⁻²), respectively. Moderate catalytic activity was recorded for the complex catalyst, namely GC-Zn(Boc-S)₂ with j_o value of (0.01 mA cm⁻²). Tafel slope values of 130 and 122 mV dec⁻¹ were calculated for ZnO and ZnO/TiO₂, respectively. Such Tafel slope values, which are close to that of the Pt wire (120 mV dec⁻¹), referred to a Volmer-controlled HER kinetics. Other important electrochemical parameters describing the kinetics of the HER, such as roughness factor (R_f) and turnover frequency (TOF) were also estimated and discussed. The high numerical values of the various HER kinetic parameters recorded for the ZnO/TiO₂ catalyst, in addition to its high stability and durability (stable for up to 10 000 continuous cathodic polarization cycles), besides maintaining its morphology and chemical composition after stability test (confirmed from SEM/EDX and XRD examinations), located it in a privileged position among the most efficient HER electrocatalysts reported in the literature.     

A study of tri(ethylene glycol)-substituted trimethylsilane (1NM3)/LiBOB as lithium battery electrolyte

Silicon-based electrolyte has emerged as a primary candidate for the development of large lithium-ion batteries for electric vehicle (EV) and other systems in which safety is a primary consideration. Comparing to the electrolyte used in the conventional lithium-ion batteries, which are flammable, volatile, and highly reactive organic carbonate solvents, silicon-based electrolytes are thermally and chemically stable, less flammable and environmental benign. Tri(ethylene glycol)-substituted trimethylsilane (1NM3) was identified as a focus of investigation due to its high conductivity and low viscosity. We present the results of a systematic investigation of the 1NM3-based electrolytes with lithium bis(oxalate)borate (LiBOB) salt, including temperature dependent ionic conductivity and lithium cell performance. Lithium-ion cell with LiNi_1/3Co_1/3Mn_1/3O₂ as the positive electrode and MAG graphite as the negative electrode has shown excellent cyclability using 1NM3-LiBOB as electrolyte.     

Tri(ethylene glycol)-substituted trimethylsilane/lithium bis(oxalate)borate electrolyte for LiMn2O4/graphite system

Silane-based electrolyte is a promising candidate for safer electrochemical energy storage devices because it is thermally and electrochemical stable, less flammable and environmental benign. In this paper, electrochemical properties of one of the silane-based electrolytes, tri(ethylene glycol)-substituted trimethylsilane (1NM3)-lithium bis(oxalate)borate (LiBOB) was studied using LiMn₂O₄ as cathode and MAG graphite as anode. When combined with LiBOB as lithium salt, the 1NM3-LiBOB electrolyte can provide solid electrolyte interface (SEI) formation due to the reductive decomposition of LiBOB at first charging cycle. Compared to the electrolyte used in the conventional lithium-ion batteries, 1NM3-LiBOB electrolyte showed compatible battery performance in LiMn₂O₄/MAG chemistry. The AC impedance measurement indicates that the activation energy (E_a) obtained from the charge transfer impedance for 1NM3-LiBOB was higher than that of the state-of-the-art electrolyte. Due to its low conductivity, the rate capability of 1NM3-LiBOB electrolyte needs to be improved.