Molecular dynamics study of the mechanical characteristics of Ni/Cu bilayer using nanoindentation

<正>In the present work,a three-dimensional molecular dynamics simulation is carried out to perform the nanoindentation experiment on Ni single crystal.The substrate indenter system is modeled using hybrid interatomic potentials including the many-body potential embedded atom method(EAM),and two-body morse potential.To simulate the indentation process,a spherical indenter(diameter = 80 A,1 A=0.1 nm) is chosen.The results show that the mechanical behaviour of a monolithic Ni is not affected by crystalline orientation.To elucidate the effect of a heterogeneous interface, three bilayer interface systems are constructed,namely Ni(100)/Cu(111),Ni(110)/Cu(111),and Ni(111)/Cu(111).The simulations along these systems clearly describe that mechanical behaviour directly depends on the lattice mismatch. The interface with the smaller mismatch between the specified crystal planes is proved to be harder and vice versa.To describe the relationship between film thickness and interface effect,we choose various values of film thickness ranging from 20 A to 50 A to perform the nanoindentation experiment.It is observed that the interface is significant only for the relatively small thickness of film and the separation between interface and the indenter tip.It is shown that with the increase in film thickness,the mechanical behaviour of the film shifts more toward that of monolithic material.     

Characterisation of some exotic fruits (Morus nigra, Morus alba, Salvadora persica and Carissa opaca) used as herbal medicines by neutron activation analysis and estimation of their nutritional value

In the under developed countries, the people of far-flung rural areas still depend to a large extent upon herbal medicines. At the foundation of usage of herbal medicine is the experience of thousands of years. The present paper deals with the characterisation of exotic fruits for essential and toxic elements. The samples include Morus nigra, Morus alba, Salvadora persica and Carissa opaca (from low and high altitude). Two standardizations of neutron activation analysis, that is, semi-absolute k ₀-instrumental neutron activation analysis (k ₀-INAA) and epithermal neutron activation analysis (ENAA) were employed for the quantification of elements. The analysis methodologies were validated by analyzing the IAEA-336 (lichen) and NIST-SRM-1572 (citrus leaves). Sixteen elements including Br, Ca, Cl, Co, Cr, Fe, I, K, Mg, Mn, Na, Rb, Sb, Sc Sr, and Zn were determined in all samples. Daily intakes of various elements from the samples were measured and compared with the dietary reference intakes. Additionally, principal component analysis was performed to extract information regarding samples and elements.     

Electrochemical Degradation of Herbicidal and Pure 2,4-Dichlorophenoxy Acetic Acid on Pb/PbO2 Modified Electrodes

Lead/lead oxide Pb/PbO₂ modified electrodes was prepared for electrocatalytic oxidation of agrochemicals including herbicidal 2,4-D (albar super) and pure 2,4-dichlorophenoxy acetic acid. The results of electrocatalytic oxidation process of the agrochemical solutions were expressed in terms of the remaining concentration and COD removal. The different operating conditions of treatment process were investigated including current density, pH, temperature, time of electrolysis, type of conductive electrolyte, and its specific conductance. This electrode gives good results for the removal of agrochemicals and COD. Also, the results showed the best conductive electrolytes is NaCl. This observation was attributed to the small size of Na⁺ and contribution of Cl^? ion in formation of OCl^?.     

Hydrothermal Deoxygenation of Graphene Oxide: Chemical and Structural Evolution

A green and facile approach for the partial deoxygenation of graphene oxide (GO) at moderate temperature (100 °C) and under atmospheric pressure, catalyzed by acidic conditions in water is reported. The chemical and structural changes in GO as a function of hydrothermal time were probed to understand the deoxygenation events. The brown GO dispersion in water was found to gradually turn black over the hydrothermal‐treatment time on account of the increasing graphitic content. FTIR, thermogravimetric (TG), Raman, and XRD analyses revealed that the labile oxygen functionalities are progressively eliminated, thereby partially restoring the π‐conjugated network. This was further corroborated by X‐ray photoelectron spectroscopy (XPS) studies based on quantitative analysis of each carbon component associated with the different chemical functionalities. Carbonyl, carboxyl, ether, and phenolic groups were found to be thermally stable, which hinders complete deoxygenation of GO and makes their dispersion in water stable, as monitored by the ζ potential. It is worth noting that deoxygenation events are expedited under acid‐catalyzed hydrothermal treatment relative to thermal deoxygenation in air.     

Hydrogen bonded co-crystallised layered isopropanol-pyrogallol[4]arenes

A novel isopropanol-pyrogallol[4]arene forms a layered structure via hydrogen bonding and C–H…π interactions. The layered structure results in encapsulation of one isopropanol molecule. The application of NMR methods to determine solution structures and crystal structures provides insight into host–guest properties and the molecular interactions between them.     

On the Reducibility of a Class of Linear Almost Periodic Differential Equations

In this paper, we use KAM methods to prove that there are positive measure Cantor sets such that for small perturbation parameters in these Cantor sets a class of almost periodic linear differential equations are reducible.     

Highly selective enrichment of phosphopeptides using poly(dibenzo‐18‐crown‐6) as a solid‐phase extraction material

A poly(dibenzo‐18‐crown‐6) was used as a new solid‐phase extraction material for the selective enrichment of phosphopeptides. Isolation of phosphopeptides was achieved based on specific ionic interactions between poly(dibenzo‐18‐crown‐6) and the phosphate group of phosphopeptides. Thus, a method was developed and optimized, including loading, washing and elution steps, for the selective enrichment of phosphopeptides. To assess this potential, tryptic digest of three proteins (α‐ casein, β‐casein and ovalbumin) was applied on poly(dibenzo‐18‐crown‐6). The nonspecific products were removed by centrifugation and washing. The spectrometric analysis was performed using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. Highly selective enrichment of both mono‐ and multiphosphorylated peptides was achieved using poly(dibenzo‐18‐crown‐6) as solid‐phase extraction material with minimum interference from nonspecific compounds. Furthermore, evaluation of the efficiency of the poly(dibenzo‐18‐crown‐6) was performed by applying the digest of egg white. Finally, quantum mechanical calculations were performed to calculate the binding energies to predict the affinity between poly(dibenzo‐18‐crown‐6) and various ligands. The newly identified solid‐phase extraction material was found to be a highly efficient tool for phosphopeptide recovery from tryptic digest of proteins.     

Preparation,characterization, and binding profile of imprinted semi-IPN cryogel composite for aluminum

Human body is greatly exposed to aluminum due to its high abundance in the environment. This nonessential metal is a threat to the patients of chronic renal disorders, as it is easily retained in their plasma and quickly accumulates in different tissues. Thus, there is great need to remove it from the aqueous environment. In this study, Al³⁺ imprinted semiinterpenetrating polymer network (semi-IPN)-based cryogel composite was prepared and applied for the purification of environmental and drinking water samples from aluminum. Poly (2-hydroxyethyl methacrylate) (pHEMA) discs were produced via cryogenic treatment and imprinted semi-IPN was introduced to the 3-(trimethoxysilyl) propyl acrylatemodified macroporous cryogel discs. The adsorption properties and selectivity of the aluminum (III) imprinted semi-IPN cryogel composite were studied in detail. The imprinted semi-IPN cryogel composite showed good selectivity towards aluminum (III) ions with the imprinting factor (IF) of 76.4 in the presence of competing copper (II), nickle (II), and iron (III) ions. The maximum adsorption capacity of 271 μmol g^-1 was obtained for aluminum (III) at pH 7.0 within 10 min using imprinted semi-IPN cryogel composite. The good selectivity and reusability of aluminum (III)-imprinted semi-IPN cryogel composite makes this material an eligible candidate for the purification of drinking water from aluminum (III) leaving important minerals remained in the water.     

Ferroelectric studies for soft Gd-modified PZT ceramics

The polycrystalline samples of gadolinium-modified lead–zirconate–titanate (Pb_1?xGd_x (Zr_0.52Ti_0.48)_1?x/4O₃) (x?=?0, 0.07, 0.10 and 0.12) (PGZT x/52/48) ceramics near morphotropic-phase boundary were prepared using conventional solid-state reaction route. XRD patterns show the formation of single-phase compounds in rhombohedral crystal system. SEM textures of the samples reveal uniform grain distribution. Frequency and temperature dependence of dielectric constant of the materials indicates non-relaxor behavior and indication of the diffuse phase transition at higher values of Gd concentration. The temperature dependence of P–E loops confirms ferroelectricity in the materials. The piezoelectric studies of the samples show enhancement in piezoelectric coefficients on substitution of Gd at the Pb site.     

A study of the effect of the loss function on Bayes Estimate,posterior risk and hazard function for Lindley distribution

In this paper, mathematical properties of Lindley distribution via Bayesian approach are derived under different loss functions. These properties include: Bayes Estimators, posterior risks and failure rate function for simulation scheme. Elicitation of hyperparameters is also discussed. A real life application to waiting time data at the bank is also described for the developed procedures (also using WinBUGS). Results are compared on the basis of posterior risk.