bluuebunny/crossref_metadata_2025 huggingface dataset:
Variance Swap Replication: Discrete or Continuous?
Authors: Le Floc’h Fabien
Published: February 2018

The popular replication formula to price variance swaps assumes continuity of traded option strikes. In practice, however, there is only a discrete set of option strikes traded on the market. We present here different discrete replication strategies and explain why the continuous replication price is more relevant.
Thermal Behavior and Structural Study of SiO2/Poly(ε-caprolactone) Hybrids Synthesized via Sol-Gel Method
Authors: Vecchio Ciprioti Stefano , Tuffi Riccardo , Dell’Era Alessandro , Dal Poggetto Francesco , Bollino Flavia
Published: February 2018

SiO2-based organic-inorganic hybrids (OIHs) are versatile materials whose properties may change significantly because of their thermal treatment. In fact, after their preparation at low temperature by the sol-gel method, they still have reactive silanol groups due to incomplete condensation reactions that can be removed by accelerating these processes upon heating them in controlled experimental conditions. In this study, the thermal behavior of pure SiO2 and four SiO2-based OIHs containing increasing amount (6, 12, 24 and 50 wt %) of poly(ε-caprolactone) (PCL) has been studied by simultaneous thermogravimetry (TG) and differential scanning calorimetry (DSC). The FTIR analysis of the gas mixture evolved at defined temperatures from the samples submitted to the TG experiments identified the mechanisms of thermally activated processes occurring upon heating. In particular, all samples already release ethanol at low temperature. Moreover, thermal degradation of PCL takes place in the richest-PCL sample, leading to 5-hexenoic acid, H2O, CO2, CO and ε-caprolactone. After the samples’ treatment at 450, 600 and 1000 °C, the X-ray diffraction (XRD) spectra revealed that they were still amorphous, while the presence of cristobalite is found in the richest-PCL material.
Use of Ultrasound in Reconditioning by Welding of Tools Used in the Process of Regenerating Rubber
Authors: Dobrotă Dan , Petrescu Valentin
Published: February 2018

Addressing the problem of reconditioning large parts is of particular importance, due to their value and to the fact that the technologies for their reconditioning are very complex. The tools used to refine regenerated rubber which measure 660 mm in diameter and 2130 mm in length suffer from a rather fast dimensional wear. Within this research, the authors looked for a welding reconditioning procedure that would allow a very good adhesion between the deposited material layer and the base material. In this regard, the MAG (Metal Active Gas) welding process was used, but the ultrasonic activation of the welding process was also considered. Thus, the wire used for welding was activated considering a variation of the frequency of ultrasounds in the range f = 18–22 kHz respectively of the oscillation amplitude A = 30–60 μm. Under these conditions it was found that the presence of ultrasonic waves during the welding cladding process results in uniform deposition of hard carbons at the grain boundary and in the elimination of any existing oxides on the deposition surface, but at the same time increases the adhesion between the base material and the additional material, all of which positively influence the wear and corrosion resistance of the tools used to refine the regenerated rubber.
Experimental Investigations on Subsequent Yield Surface of Pure Copper by Single-Sample and Multi-Sample Methods under Various Pre-Deformation
Authors: Liu Gui-Long , Huang Shi-Hong , Shi Che-Si , Zeng Bin , Zhang Ke-Shi , Zhong Xian-Ci
Published: February 2018

Using copper thin-walled tubular specimens, the subsequent yield surfaces under pre-tension, pre-torsion and pre-combined tension-torsion are measured, where the single-sample and multi-sample methods are applied respectively to determine the yield stresses at specified offset strain. The rule and characteristics of the evolution of the subsequent yield surface are investigated. Under the conditions of different pre-strains, the influence of test point number, test sequence and specified offset strain on the measurement of subsequent yield surface and the concave phenomenon for measured yield surface are studied. Moreover, the feasibility and validity of the two methods are compared. The main conclusions are drawn as follows: (1) For the single or multi-sample method, the measured subsequent yield surfaces are remarkably different from cylindrical yield surfaces proposed by the classical plasticity theory; (2) there are apparent differences between the test results from the two kinds of methods: the multi-sample method is not influenced by the number of test points, test order and the cumulative effect of residual plastic strain resulting from the other test point, while those are very influential in the single-sample method; and (3) the measured subsequent yield surface may appear concave, which can be transformed to convex for single-sample method by changing the test sequence. However, for the multiple-sample method, the concave phenomenon will disappear when a larger offset strain is specified.
Thermal Properties of SiOC Glasses and Glass Ceramics at Elevated Temperatures
Authors: Stabler Christina , Reitz Andreas , Stein Peter , Albert Barbara , Riedel Ralf , Ionescu Emanuel
Published: February 2018

In the present study, the effect of the chemical and phase composition on the thermal properties of silicon oxide carbides (SiOC) has been investigated. Dense monolithic SiOC materials with various carbon contents were prepared and characterized with respect to their thermal expansion, as well as thermal conductivity. SiOC glass has been shown to exhibit low thermal expansion (e.g., ca. 3.2 × 10−6 K−1 for a SiOC sample free of segregated carbon) and thermal conductivity (ca. 1.5 W/(m∙K)). Furthermore, it has been observed that the phase separation, which typically occurs in SiOC exposed to temperatures beyond 1000–1200 °C, leads to a decrease of the thermal expansion (i.e., to 1.83 × 10−6 K−1 for the sample above); whereas the thermal conductivity increases upon phase separation (i.e., to ca. 1.7 W/(m∙K) for the sample mentioned above). Upon adjusting the amount of segregated carbon content in SiOC, its thermal expansion can be tuned; thus, SiOC glass ceramics with carbon contents larger than 10–15 vol % exhibit similar coefficients of thermal expansion to that of the SiOC glass. Increasing the carbon and SiC content in the studied SiOC glass ceramics leads to an increase in their thermal conductivity: SiOC with relatively large carbon and silicon carbides (SiC) volume fractions (i.e., 12–15 and 20–30 vol %, respectively) were shown to possess thermal conductivities in the range from 1.8 to 2.7 W/(m∙K).
Carrier-Free Microspheres of an Anti-Cancer Drug Synthesized via a Sodium Catalyst for Controlled-Release Drug Delivery
Authors: Xie Yong , Ma Xinxin , Liu Xujie , Long Qingming , Wang Yu , Yao Youwei , Cai Qiang
Published: February 2018

There are several challenges involved in the development of effective anti-cancer drugs, including accurate drug delivery without toxic side effects. Possible systemic toxicity and the rapid biodegradation of drug carriers are potential risks in the use of carriers for drug-delivery formulations. Therefore, the carrier-free drug delivery of an anti-cancer drug is desirable. Herein, 4-amino-2-benzyl-6-methylpyrimidine (ABMP) was synthesized via a new method using a sodium catalyst, and proved to be effective in inducing breast cancer cell (MDA-MB-231) apoptosis. Moreover, the transparent amorphous state solid of ABMP was demonstrated to have a slow-release property in phosphate buffer solution (PBS). Microspheres of ABMP were prepared with diameters in the range of 5–15 μm. The slow-release property of the ABMP microspheres indicated their potential use for controlled-release drug delivery. We believe that microspheres of ABMP have potential as a new kind of carrier-free anti-cancer drug delivery system.
Investigation of Surface Morphology of 6H-SiC Irradiated with He+ and H2+ Ions
Authors: Shen Qiang , Ran Guang , Zhou Wei , Ye Chao , Feng Qijie , Li Ning
Published: February 2018

Light ion implantation is one of the important procedures of smart cut for SiC-based semiconductor fabrication. This work investigated the surface morphologies and microstructures of single crystal 6H-SiC irradiated by one or both of H2+ and He+ ions at room temperature and then annealed at specific temperatures. Blisters evolved from the coalescence of H nanocracks were formed in the H2+ and He++H2+ irradiated sample surface, while circular ripples originated from the pressure release of helium bubbles after high temperature annealing were formed in the He+ irradiated sample surface. The lateral radius a of the blisters in the irradiated sample with low H2+ fluence was larger than that in the irradiated sample with high H2+ fluence and with He++H2+ ions. About 8–58% of implanted H atoms contributed to the formation of the blisters. Compared with other irradiated samples, the ratio of w0/a and the density of the blisters in the He++H2+ irradiated samples were largest. The stress field of the blisters was simulated using finite element method and the inner pressure in the blisters was also calculated. The corresponding mechanism was analyzed and discussed.
Comparison of Ultem 9085 Used in Fused Deposition Modelling (FDM) with Polytherimide Blends
Authors: Cicala Gianluca , Ognibene Giulia , Portuesi Salvatore , Blanco Ignazio , Rapisarda Mario , Pergolizzi Eugenio , Recca Giuseppe
Published: February 2018

Polyetherimide (PEI) blends modified by either polycarbonate (PC) or polyethylene terephthalate glycol-modified (PETG) were prepared. The latter modifier (PETG) was an industrial grade widely used for fused deposition modelling (FDM) printing. PEI blends were compared to Ultem 9085, which is the standard PEI grade for FDM printing in advanced applications. All the blends were thoroughly characterized in terms of their rheological, morphological, thermomechanical and tensile properties. Ultem 9085 showed improved rheology for processing over standard PEI. PEI/PC blends with 10 wt % of modifier developed here closely matched the viscosity behavior of Ultem 9085. On the other hand, the blends with low PC content (i.e., less than 20 wt %) outperformed Ultem 9085 in terms of thermal and tensile properties. When PETG was added, similar tensile properties to Ultem 9085 were found. The immiscibility for PC contents higher than 20 wt % deteriorated the tensile properties, making it less attractive for applications, although melt viscosity decreased further for increasing PC contents.
Unusual Electrical Transport Driven by the Competition between Antiferromagnetism and Ferromagnetism in Antiperovskite Mn3Zn1−xCoxN
Authors: Chu Lihua , Ding Lei , Wang Cong , Li Meicheng , Guo Yanjiao , Liu Zhuohai
Published: February 2018

The magnetic, electrical transport and thermal expansion properties of Mn3Zn1−xCoxN (x = 0.2, 0.4, 0.5, 0.7, 0.9) have been systematically investigated. Co-doping in Mn3ZnN complicates the magnetic interactions, leading to a competition between antiferromagnetism and ferromagnetism. Abrupt resistivity jump phenomenon and negative thermal expansion behavior, both associated with the complex magnetic transition, are revealed in all studied cases. Furthermore, semiconductor-like transport behavior is found in sample x = 0.7, distinct from the metallic behavior in other samples. Below 50 K, resistivity minimum is observed in samples x = 0.4, 0.7, and 0.9, mainly caused by e-e scattering mechanism. We finally discussed the strong correlation among unusual electrical transport, negative thermal expansion and magnetic transition in Mn3Zn1−xCoxN, which allows us to conclude that the observed unusual electrical transport properties are attributed to the shift of the Fermi energy surface entailed by the abrupt lattice contraction.
Chemical Sensing Applications of ZnO Nanomaterials
Authors: Chaudhary Savita , Umar Ahmad , Bhasin K. , Baskoutas Sotirios
Published: February 2018

Recent advancement in nanoscience and nanotechnology has witnessed numerous triumphs of zinc oxide (ZnO) nanomaterials due to their various exotic and multifunctional properties and wide applications. As a remarkable and functional material, ZnO has attracted extensive scientific and technological attention, as it combines different properties such as high specific surface area, biocompatibility, electrochemical activities, chemical and photochemical stability, high-electron communicating features, non-toxicity, ease of syntheses, and so on. Because of its various interesting properties, ZnO nanomaterials have been used for various applications ranging from electronics to optoelectronics, sensing to biomedical and environmental applications. Further, due to the high electrochemical activities and electron communication features, ZnO nanomaterials are considered as excellent candidates for electrochemical sensors. The present review meticulously introduces the current advancements of ZnO nanomaterial-based chemical sensors. Various operational factors such as the effect of size, morphologies, compositions and their respective working mechanisms along with the selectivity, sensitivity, detection limit, stability, etc., are discussed in this article.
Preliminary Investigation of Poly-Ether-Ether-Ketone Based on Fused Deposition Modeling for Medical Applications
Authors: Zhao Feng , Li Dichen , Jin Zhongmin
Published: February 2018

Poly-ether-ether-ketone (PEEK) fabricated by fused deposition modeling for medical applications was evaluated in terms of mechanical strength and in vitro cytotoxicity in this study. Orthogonal experiments were firstly designed to investigate the significant factors on tensile strength. Nozzle temperature, platform temperature, and the filament diameter were tightly controlled for improved mechanical strength performance. These sensitive parameters affected the interlayer bonding and solid condition in the samples. Fourier transform infrared (FTIR) spectrometry analysis was secondly conducted to compare the functional groups in PEEK granules, filaments, and printed parts. In vitro cytotoxicity test was carried out at last, and no toxic substances were introduced during the printing process.
Magnetic Characterization of Direct-Write Free-Form Building Blocks for Artificial Magnetic 3D Lattices
Authors: Al Mamoori Mohanad , Keller Lukas , Pieper Jonathan , Barth Sven , Winkler Robert , Plank Harald , Müller Jens , Huth Michael
Published: February 2018

Three-dimensional (3D) nanomagnetism, where spin configurations extend into the vertical direction of a substrate plane allow for more complex, hierarchical systems and the design of novel magnetic effects. As an important step towards this goal, we have recently demonstrated the direct-write fabrication of freestanding ferromagnetic 3D nano-architectures of ferromagnetic CoFe in shapes of nano-tree and nano-cube structures by means of focused electron beam induced deposition. Here, we present a comprehensive characterization of the magnetic properties of these structures by local stray-field measurements using a high-resolution micro-Hall magnetometer. Measurements in a wide range of temperatures and different angles of the externally applied magnetic field with respect to the surface plane of the sensor are supported by corresponding micromagnetic simulations, which explain the overall switching behavior of in part rather complex magnetization configurations remarkably well. In particular, the simulations yield coercive and switching fields that are in good quantitative correspondence with the measured coercive and switching fields assuming a bulk metal content of 100 at % consisting of bcc Co 3 Fe. We show that thermally-unstable magnetization states can be repetitively prepared and their lifetime controlled at will, a prerequisite to realizing dynamic and thermally-active magnetic configurations if the building blocks are to be used in lattice structures.
Numerical Study of Lateral Migration of Elliptical Magnetic Microparticles in Microchannels in Uniform Magnetic Fields
Authors: Zhang Jie , Wang Cheng
Published: February 2018

This work reports numerical investigation of lateral migration of a paramagnetic microparticle of an elliptic shape in a plane Poiseuille flow of a Newtonian fluid under a uniform magnetic field by direct numerical simulation (DNS). A finite element method (FEM) based on the arbitrary Lagrangian–Eulerian (ALE) approach is used to study the effects of strength and direction of the magnetic field, particle–wall separation distance and particle shape on the lateral migration. The particle is shown to exhibit negligible lateral migration in the absence of a magnetic field. When the magnetic field is applied, the particle migrates laterally. The migration direction depends on the direction of the external magnetic field, which controls the symmetry property of the particle rotational velocity. The magnitude of net lateral migration velocity over a π cycle is increased with the magnetic field strength when the particle is able to execute complete rotations, expect for α = 45° and 135°. By investigating a wide range of parameters, our direct numerical simulations yield a comprehensive understanding of the particle migration mechanism. Based on the numerical data, an empirical scaling relationship is proposed to relate the lateral migration distance to the asymmetry of the rotational velocity and lateral oscillation amplitude. The scaling relationship provides useful guidelines on design of devices to manipulate nonspherical micro-particles, which have important applications in lab-on-a-chip technology, biology and biomedical engineering.
Ecdysonelactones, Ecdysteroids from the Tropical Eastern Pacific Zoantharian Antipathozoanthus hickmani
Authors: Guillen Paul , Calabro Kevin , Jaramillo Karla , Dominguez Cristobal , Genta-Jouve Grégory , Rodriguez Jenny , Thomas Olivier
Published: February 2018

Despite a large occurrence, especially over the Pacific Ocean, the chemical diversity of marine invertebrates belonging to the order Zoantharia is largely underexplored. For the two species of the genus Antipathozoanthus no chemical study has been reported so far. The first chemical investigation of Antipathozoanthus hickmani collected at the Marine Protected Area “El Pelado”, Santa Elena, Ecuador, led to the isolation of four new ecdysteroid derivatives named ecdysonelactones. The structures of ecdysonelactones A–D (1–4) were determined based on their spectroscopy data, including 1D and 2D NMR and HRMS. The four compounds of this family of ecdysteroids feature an unprecedented γ-lactone fused at the C-2/C-3 position of ring A. These derivatives exhibited neither antimicrobial nor cytotoxic activities.
Strain Hardening Behavior and Microstructure Evolution of High-Manganese Steel Subjected to Interrupted Tensile Tests
Authors: Grajcar Adam , Kozłowska Aleksandra , Grzegorczyk Barbara
Published: February 2018

Strain hardening behavior and the corresponding microstructure evolution of the high-manganese steel with additions of Si and Al were investigated in this study. Thermomechanically processed and solution-heat-treated sheet steels were compared under conditions of interrupted tensile tests. Relationships between microstructure and strain hardening were assessed for different strain levels using light microscopy and scanning electron microscopy techniques. It was found that the deformation of both steels at low strain levels was dominated by dislocation glide before the occurrence of mechanical twinning. The amount of twins, slip lines, and bands was increasing gradually up to the point of necking. As the strain level increased, dislocation density within twinning areas becomes higher, which enhances the strength, the work hardening exponent, and the work hardening rate of the investigated high-manganese sheet steels.
Evolution of Microstructure and Mechanical Properties of a CoCrFeMnNi High-Entropy Alloy during High-Pressure Torsion at Room and Cryogenic Temperatures
Authors: Zherebtsov Sergey , Stepanov Nikita , Ivanisenko Yulia , Shaysultanov Dmitry , Yurchenko Nikita , Klimova Margarita , Salishchev Gennady
Published: February 2018

High-pressure torsion (HPT) is applied to a face-centered cubic CoCrFeMnNi high-entropy alloy at 293 and 77 K. Processing by HPT at 293 K produced a nanostructure consisted of (sub)grains of ~50 nm after a rotation for 180°. The microstructure evolution is associated with intensive deformation-induced twinning, and substructure development resulted in a gradual microstructure refinement. Deformation at 77 K produces non-uniform structure composed of twinned and fragmented areas with higher dislocation density then after deformation at room temperature. The yield strength of the alloy increases with the angle of rotation at HPT at room temperature at the cost of reduced ductility. Cryogenic deformation results in higher strength in comparison with the room temperature HPT. The contribution of Hall–Petch hardening and substructure hardening in the strength of the alloy in different conditions is discussed.
Effects of Zr Additive on Microstructure, Mechanical Properties, and Fractography of Al-Si Alloy
Authors: Qian Hui , Zhu Degui , Hu Chunfeng , Jiang Xiaosong
Published: February 2018

The effects of Zr additive on the microstructure, mechanical properties, and fracture behavior of Al-Si alloy were systematically investigated. The additive of Zr obviously reduced the size of Si particles and changed its morphology. Grain size refinement was promoted by the reaction between Al and Zr forming Al3Zr and ZrSi2 compounds. Compared to a Zr-free alloy, the additive enhanced the tensile strength, compressive strength, shear strength, and hardness. The optimized Zr content was 2.4 wt % corresponding to a tensile strength of 231.1 MPa, compressive strength of 343.1 MPa, shear strength of 174.9 MPa, and hardness of 85.5 HV, greater than those of the Zr-free alloy. This illustrates that fine-grain strengthening and the existence of a second phase can improve the mechanical properties of Al-Si alloy. The fracture surface of Al-Si alloy without Zr additive showed a brittle fracture mode and there were no pits on the fractured surface. In the presence of Zr addictive, a typical plastic deformation with a large amount of pits was evidenced.
Finite Element Simulation of the Presta Joining Process for Assembled Camshafts: Application to Aluminum Shafts
Authors: Scherzer Robert , Fritsch Sebastian , Landgraf Ralf , Ihlemann Jörn , Wagner Martin
Published: February 2018

This work shows a sequence of numerical models for the simulation of the Presta joining process: a well-established industrial process for manufacturing assembled camshafts. The operation is divided into two sub-steps: the rolling of the shaft to widen the cam seat and the joining of the cam onto the shaft. When manufactured, the connection is tested randomly by loading it with a static torque. Subsequently, there are three numerical models using the finite element method. Additionally, a material model of finite strain viscoplasticity with nonlinear kinematic hardening is used throughout the whole simulation process, which allows a realistic representation of the material behavior even for large deformations. In addition, it enables a transfer of the deformation history and of the internal stresses between different submodels. This work also shows the required parameter identification and the associated material tests. After comparing the numerical results with experimental studies of the manufacturing process for steel-steel connections, the models are used to extend the joining process to the utilization of aluminum shafts.
Atomistic Simulations to Predict Favored Glass-Formation Composition and Ion-Beam-Mixing of Nano-Multiple-Metal-Layers to Produce Ternary Amorphous Films
Authors: Yang M. , Li J. , Liu B. , Liu J.
Published: February 2018

Based on the framework of long-range empirical formulas, the interatomic potentials were constructed for the Ni-Nb-Mo (fcc-bcc-bcc) and Ni-Zr-Mo (fcc-hcp-bcc) ternary metal systems. Applying the constructed potentials, atomistic simulations were performed to predict the energetically favored glass formation regions (GFRs) in the respective composition triangles of the systems. In addition, the amorphization driving forces (ADFs), i.e., the energy differences between the solid solutions and disordered phases, were computed and appeared to correlate with the so-called glass forming abilities. To verify the atomistic prediction, ion beam mixing with nano-multiple-metal-layers was carried out to produce ternary amorphous films. The results showed that the composition of ternary amorphous films obtained by ion beam mixing all locate inside the GFRs, supporting the predictions of atomistic simulations. Interestingly, the minimum ion dosage required for amorphization showed a negative correlation with the calculated ADF, implying that the predicted amorphization driving force could be an indicator of the glass formation ability.
Evaluation of Primary Water Stress Corrosion Cracking Resistance of Three Heats of Alloy 600 in 400 °C Hydrogenated Steam Condition
Authors: Yun Eunsub , Chung Hansub , Jang Changheui
Published: February 2018

For Alloy 600, primary water stress corrosion cracking (PWSCC) is one of the key material degradation mechanisms in pressurized water reactors (PWRs). To identify the governing factors of PWSCC resistance, a systematic investigation into the role of each factor was performed. A PWSCC initiation test was performed for 3 heats of Alloy 600 in the 400 °C hydrogenated steam condition. Based on the test results, the effects of known factors like chemical composition, mechanical strength, grain boundary carbide coverage, grain boundary character, and surface cold work on PWSCC resistance were discussed. In addition, surface oxide morphology and penetrative oxide depth was compared. From this study, grain boundary character was considered to be the most dominant factor affecting the PWSCC resistance.
Carbonic Anhydrase IX (CAIX), Cancer, and Radiation Responsiveness
Authors: Ward Carol , Meehan James , Gray Mark , Kunkler Ian , Langdon Simon , Argyle David
Published: February 2018

Carbonic anhydrase IX has been under intensive investigation as a therapeutic target in cancer. Studies demonstrate that this enzyme has a key role in pH regulation in cancer cells, allowing these cells to adapt to the adverse conditions of the tumour microenviroment. Novel CAIX inhibitors have shown efficacy in both in vitro and in vivo pre-clinical cancer models, adversely affecting cell viability, tumour formation, migration, invasion, and metastatic growth when used alone. In co-treatments, CAIX inhibitors may enhance the effects of anti-angiogenic drugs or chemotherapy agents. Research suggests that these inhibitors may also increase the response of tumours to radiotherapy. Although many of the anti-tumour effects of CAIX inhibition may be dependent on its role in pH regulation, recent work has shown that CAIX interacts with several of the signalling pathways involved in the cellular response to radiation, suggesting that pH-independent mechanisms may also be an important basis of its role in tumour progression. Here, we discuss these pH-independent interactions in the context of the ability of CAIX to modulate the responsiveness of cancer to radiation.
Ultrasonically Assisted Single Point Diamond Turning of Optical Mold of Tungsten Carbide
Authors: Li Zhanjie , Jin Gang , Fang Fengzhou , Gong Hu , Jia Haili
Published: February 2018

To realize high efficiency, low/no damage and high precision machining of tungsten carbide used for lens mold, a high frequency ultrasonic vibration cutting system was developed at first. Then, tungsten carbide was precisely machined with a polycrystalline diamond (PCD) tool assisted by the self-developed high frequency ultrasonic vibration cutting system. Tool wear mechanism was investigated in ductile regime machining of tungsten carbide. The cutter back-off phenomenon in the process was analyzed. The subsequent experimental results of ultra-precision machining with a single crystal diamond tool showed that: under the condition of high frequency ultrasonic vibration cutting, nano-scale surface roughness can be obtained by the diamond tool with smaller tip radius and no defects like those of ground surface were found on the machined surface. Tool wear mechanisms of the single crystal diamond tool are mainly abrasive wear and micro-chipping. To solve the problem, a method of inclined ultrasonic vibration cutting with negative rake angle was put forward according to force analysis, which can further reduce tool wear and roughness of the machined surface. The investigation was important to high efficiency and quality ultra-precision machining of tungsten carbide.
Bacterial Microbiota of Rice Roots: 16S-Based Taxonomic Profiling of Endophytic and Rhizospheric Diversity, Endophytes Isolation and Simplified Endophytic Community
Authors: Moronta-Barrios Felix , Gionechetti Fabrizia , Pallavicini Alberto , Marys Edgloris , Venturi Vittorio
Published: February 2018

Rice is currently the most important food crop in the world and we are only just beginning to study the bacterial associated microbiome. It is of importance to perform screenings of the core rice microbiota and also to develop new plant-microbe models and simplified communities for increasing our understanding about the formation and function of its microbiome. In order to begin to address this aspect, we have performed a 16S rDNA taxonomic bacterial profiling of the rhizosphere and endorhizosphere of two high-yield rice cultivars—Pionero 2010 FL and DANAC SD20A—extensively grown in Venezuela in 2014. Fifteen putative bacterial endophytes were then isolated from surface-sterilized roots and further studied in vitro and in planta. We have then performed inoculation of rice seedlings with a simplified community composed by 10 of the isolates and we have tracked them in the course of 30 days in greenhouse cultivation. The results obtained suggest that a set was able to significantly colonize together the rice endorhizospheres, indicating possible cooperation and the ability to form a stable multispecies community. This approach can be useful in the development of microbial solutions for a more sustainable rice production.
Origin of Reverse Zoned Cr-Spinels from the Paleoproterozoic Yanmenguan Mafic–Ultramafic Complex in the North China Craton
Authors: Bai Yang , Su Ben-Xun , Xiao Yan , Lenaz Davide , Asamoah Sakyi Patrick , Liang Zi , Chen Chen , Yang Sai-Hong
Published: February 2018

We conducted petrological and mineral chemistry investigations of Cr-spinel in ultramafic rocks of the Yanmenguan mafic–ultramafic complex in the North China Craton. The Cr-spinel grains occur as inclusions in enstatite, tschermakite, phlogopite, and olivine, or as interstitial grains among the aforementioned silicate minerals, and show concentric or asymmetrical textures. Back-scattered electron and elemental images and compositional profiles of the spinel grains indicate the presence of Cr- and Fe-rich cores and Al- and Mg-rich rims. The host silicate minerals display a decrease in Al and Mg contents accompanied by an increase in Cr and Fe away from the spinel. These textures and compositional variations suggest that subsolidus elemental exchange more likely gave rise to the compositional zonation, resulting in the transfer of Al and Mg from the silicate minerals to the spinel. The Mn, Ni, and Ti contents in spinel and the major elements of olivine-hosted spinel are relatively stable during subsolidus elemental diffusion and thus are more reliable tracers of primary high-temperature processes. The temperature estimates reveal that the subsolidus diffusion might have occurred at 600–720 °C, which could be linked to the regional metamorphic event.
Vanadium Transitions during Roasting-Leaching Process of Vanadium Extraction from Stone Coal
Authors: Zhao Yunliang , Chen Licai , Yi Hao , Zhang Yimin , Song Shaoxian , Bao Shenxu
Published: February 2018

The vanadium occurrence in stone coal, water leaching, and acid leaching residue was investigated by energy dispersive spectrometer (EDS) mapping and point analysis, and the vanadium transitions during roasting-leaching of stone coal were revealed. In the roasting process, vanadium-bearing muscovite is converted to K-Na-feldspar, accompanying the liberation of vanadium. Most liberated vanadium reacts with sodium salt to generate water-soluble sodium vanadate, some reacts with calcite in stone coal to form water-insoluble calcium vanadate, and other liberated vanadium exists as free vanadium oxide. However, for coarse muscovite grains, the reaction of muscovite converted to K-Na-feldspar only occurs at the outer margin of muscovite grains, and the vanadium in the interior of muscovite grains is not liberated. During water leaching, the sodium vanadate is leached out. The calcium vanadate and free vanadium oxide are dissolved out in the process of acid leaching, and the vanadium, presenting in muscovite grains surrounded by K-Na-feldspar, still remains in the acid leaching residue. Two suggestions, including optimization of grinding-classification process and adopting microwave roasting, were proposed for improving vanadium recovery according to the vanadium transition rules.
Quantification and Variability Analysis of Lignin Optical Properties for Colour-Dependent Industrial Applications
Authors: Ajao Olumoye , Jeaidi Jawad , Benali Marzouk , Restrepo Andrea , El Mehdi Naima , Boumghar Yacine
Published: February 2018

Lignin availability has increased significantly due to the commercialization of several processes for recovery and further development of alternatives for integration into Kraft pulp mills. Also, progress in lignin characterization, understanding of its chemistry as well as processing methods have resulted in the identification of novel lignin-based products and potential derivatives, which can serve as building block chemicals. However, all these have not led to the successful commercialization of lignin-based chemicals and materials. This is because most analyses and characterizations focus only on the technical suitability and quantify only the composition, functional groups present, size and morphology. Optical properties, such as the colour, which influences the uptake by users for diverse applications, are neither taken into consideration nor analysed. This paper investigates the quantification of lignin optical properties and how they can be influenced by process operating conditions. Lignin extraction conditions were also successfully correlated to the powder colour. About 120 lignin samples were collected and the variability of their colours quantified with the CIE L*a*b* colour space. In addition, a robust and reproducible colour measurement method was developed. This work lays the foundation for identifying chromophore molecules in lignin, as a step towards correlating the colour to the functional groups and the purity.
Bioactive Compounds in Cornelian Cherry Vinegars
Authors: Kawa-Rygielska Joanna , Adamenko Kinga , Kucharska Alicja , Piórecki Narcyz
Published: February 2018

We analyzed the effect of Cornelian cherry varieties differing in fruit color (‘Yantaryi’—yellow fruits, ‘Koralovyi’—coral fruits, ‘Podolski’—red fruits) and the production method on the physicochemical and antioxidative properties of Cornelian cherry vinegars, and on their content of iridoids and polyphenols. Acetic fermentation was conducted by two methods: I) single-stage (spontaneous) acetic fermentation, without inoculation with microorganisms, and II) two-stage fermentation in which the first stage involved the use of Saccharomyces bayanus—Safspirit fruit yeast for alcoholic fermentation, and the second one included spontaneous acetic fermentation. Acetic acid, glycerol, individual iridoids, phenolic acids, flavonols, and anthocyanins were quantified by a high-performance liquid chromatography (HPLC) method. The antioxidative activity was determined based on the following tests: 2,2-Diphenyl-2-picryl-hydrazyl (DPPH•), 2,2′-Azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid (ABTS•+), and ferric reducing antioxidant power (FRAP), while the total polyphenols content was determined using the Folin-Ciocialteu (F-C) reagent test. Both the Cornelian cherry variety and vinegar production method affected the antioxidative properties as well as concentrations of iridoids and polyphenols in the finished product. The concentration of total polyphenols (F-C) in vinegars ranged from 326.60 to 757.27 mg gallic acids equivalents (GAE)/100 mL vinegar, whereas the antioxidative activity assayed with the DPPH• and FRAP methods was the highest in the vinegars produced from the coral and red varieties of Cornelian cherry with the two-stage method. Loganic acid predominated among the identified iridoids, reaching a concentration of 185.07 mg loganic acid (LA)/100 mL in the vinegar produced in the two-stage fermentation from the coral-fruit variety. Caffeoylquinic acid derivatives were the main representatives among the identified phenolic compounds. The results of this study demonstrate Cornelian cherry vinegars to be rich sources of biologically-active iridoids and phenolic compounds with antioxidative properties.
Complex Formation of Resorufin and Resazurin with Β-Cyclodextrins: Can Cyclodextrins Interfere with a Resazurin Cell Viability Assay?
Authors: Csepregi Rita , Lemli Beáta , Kunsági-Máté Sándor , Szente Lajos , Kőszegi Tamás , Németi Balázs , Poór Miklós
Published: February 2018

Resazurin (or Alamar Blue) is a poorly fluorescent dye. During the cellular reduction of resazurin, its highly fluorescent product resorufin is formed. Resazurin assay is a commonly applied method to investigate viability of bacterial and mammalian cells. In this study, the interaction of resazurin and resorufin with β-cyclodextrins was investigated employing spectroscopic and molecular modeling studies. Furthermore, the influence of β-cyclodextrins on resazurin-based cell viability assay was also tested. Both resazurin and resorufin form stable complexes with the examined β-cyclodextrins (2.0–3.1 × 103 and 1.3–1.8 × 103 L/mol were determined as binding constants, respectively). Cells were incubated for 30 and 120 min and treated with resazurin and/or β-cyclodextrins. Our results suggest that cyclodextrins are able to interfere with the resazurin-based cell viability assay that presumably results from the following mechanisms: (1) inhibition of the cellular uptake of resazurin and (2) enhancement of the fluorescence signal of the formed resorufin.
Advances in Heparins and Related Research. An Epilogue
Authors: Fareed Jawed , Bacher Peter , Jeske Walter
Published: February 2018

The discovery of heparin in 1916 by Jay McLean, a medical student at Johns Hopkins University, not only provided a universal anticoagulant, but also laid the foundation for the discipline of hemostasis and thrombosis[...]
In Vitro and In Vivo Antioxidant Activities of the Flowers and Leaves from Paeonia rockii and Identification of Their Antioxidant Constituents by UHPLC-ESI-HRMSn via Pre-Column DPPH Reaction
Authors: Bao Yating , Qu Yan , Li Jinhua , Li Yanfang , Ren Xiaodong , Maffucci Katherine , Li Ruiping , Wang Zhanguo , Zeng Rui
Published: February 2018

The genus Paeonia, also known as the “King of Flowers” in China, is an important source of traditional Chinese medicine (TCM). Plants of this genus have been used to treat a range of cardiovascular and gynecological diseases. However, the potential pharmacological activity of one particular species, Paeonia rockii, has not been fully investigated. In the first part of the present study, 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic) acid (ABTS), reducing power assays, and metal ion chelating assays were used to investigate the in vitro antioxidant activities of Paeonia rockii. In the second portion of the study, a mouse model of d-galactose-induced aging was used to validate the antioxidant effects of the flowers from Paeonia rockii in vivo. Lastly, potential antioxidant constituents were screened and identified by ultra-high pressure liquid chromatography and electrospray ionization coupled with high-resolution mass spectrometry (UHPLC-ESI-HRMSn) combined with the DPPH assay. Results indicated that the flowers and leaves exhibited stronger antioxidant activity than ascorbic acid in vitro. The therapeutic effect of Paeonia rockii was determined in relation to the levels of biochemical indicators, such as 8-iso-prostaglandin F2α (8-iso PGF2α) in the serum, superoxide dismutase (SOD), protein carbonyl, malondialdehyde (MDA), and glutathione (GSH) in the liver and brain, after daily intra-gastric administration of different concentrations of extracts (100, 200 and 400 mg/kg) for three weeks. The levels of 8-iso PGF2α (p < 0.01) and protein carbonyl groups (p < 0.01) were significantly reduced, whereas those of SOD (p < 0.05) had significantly increased, indicating that components of the flowers of Paeonia rockii had favorable antioxidant activities in vivo. Furthermore, UHPLC-ESI-HRMSn, combined with pre-column DPPH reaction, detected 25 potential antioxidant compounds. Of these, 18 compounds were tentatively identified, including 11 flavonoids, four phenolic acids, two tannins, and one monoterpene glycoside. This study concluded that the leaves and flowers from Paeonia rockii possess excellent antioxidant properties, highlighting their candidacy as “new” antioxidants, which can be utilized therapeutically to protect the body from diseases caused by oxidative stress.
Improved Anticancer Effect of Magnetite Nanocomposite Formulation of GALLIC Acid (Fe3O4-PEG-GA) Against Lung, Breast and Colon Cancer Cells
Authors: Rosman Raihana , Saifullah Bullo , Maniam Sandra , Dorniani Dena , Hussein Mohd , Fakurazi Sharida
Published: February 2018

Lung cancer, breast cancer and colorectal cancer are the most prevalent fatal types of cancers globally. Gallic acid (3,4,5-trihydroxybenzoic acid) is a bioactive compound found in plants and foods, such as white tea, witch hazel and it has been reported to possess anticancer, antioxidant and anti-inflammatory properties. In this study we have redesigned our previously reported anticancer nanocomposite formulation with improved drug loading based on iron oxide magnetite nanoparticles coated with polyethylene glycol and loaded with anticancer drug gallic acid (Fe3O4-PEG-GA). The in vitro release profile and percentage drug loading were found to be better than our previously reported formulation. The anticancer activity of pure gallic acid (GA), empty carrier (Fe3O4-PEG) nanocarrier and of anticancer nanocomposite (Fe3O4-PEG-GA) were screened against human lung cancer cells (A549), human breast cancer cells (MCF-7), human colon cancer cells (HT-29) and normal fibroblast cells (3T3) after incubation of 24, 48 and 72 h using (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) MTT assay. The designed formulation (Fe3O4-PEG-GA) showed better anticancer activity than free gallic acid (GA). The results of the in vitro studies are highly encouraging to conduct the in vivo studies.
Electrochemical Preparation of Polyaniline Nanowires with the Used Electrolyte Solution Treated with the Extraction Process and Their Electrochemical Performance
Authors: Wu Ying , Wang Jixiao , Ou Bin , Zhao Song , Wang Zhi , Wang Shichang
Published: February 2018

Electrochemical polymerization of aniline is one of the most promising methods to prepare polyaniline (PANI) materials. However, during this process, the electrolyte solution must be replaced after electropolymerization of a certain time because of the generation and the accumulation of the by-products, which have significant effects on the morphology, purity and properties of PANI products. Treatment and recycling of the used electrolyte solution are worthwhile to study to reduce the high treatment cost of the used electrolyte solution containing aniline and its polymerization by-products. Here, the composition of the used electrolyte solution was separated and determined by high performance liquid chromatography coupled with diode array detection (HPLC-DAD) in the range of ultraviolet and visible (UV-Vis) light. The analysis results revealed that the used electrolyte solution consisted of aniline, p-hydroquinone (HQ), p-benzoquinone (BQ), co-oligomers of aniline and p-benzoquinone (CAB) and acid. Then, n-octanol and 2-octanone were selected as extracts to remove HQ, BQ and CAB from the used electrolyte solution. Following that, the recycled electrolyte solution was prepared by adjusting the concentration of aniline and acid of the aqueous phase, and the electrochemical polymerization process was conducted. Finally, the obtained PANI was characterized by scanning electron microscope (SEM) and electrochemical methods. The experimental results clearly demonstrate that the morphology and specific capacitance of PANI produced from the recycled electrolyte solution can be recovered completely. This research paves the way for reusing the used electrolyte solution for aniline electrochemical polymerization.
Clearly Transparent Nanopaper from Highly Concentrated Cellulose Nanofiber Dispersion Using Dilution and Sonication
Authors: Kasuga Takaaki , Isobe Noriyuki , Yagyu Hitomi , Koga Hirotaka , Nogi Masaya
Published: February 2018

Nanopaper prepared from holocellulose pulp is one of the best substrates for flexible electronics because of its high thermal resistance and high clear transparency. However, the clearness of nanopaper decreases with increasing concentration of the starting cellulose nanofiber dispersion—with the use of a 2.2 wt % dispersion, for example—resulting in translucent nanopaper with a high haze of 44%. To overcome this problem, we show that the dilution of this high-concentration dispersion with water followed by sonication for 10 s reduces the haze to less than 10% while maintaining the high thermal resistance of the nanopaper. Furthermore, the combination of water dilution and a short sonication treatment improves the clearness of the nanopaper, which would translate into cost savings for the transportation and storage of this highly concentrated cellulose nanofiber dispersion. Finally, we demonstrate the improvement of the electrical conductivity of clear transparent nanopaper prepared from an initially high-concentration dispersion by dropping and heating silver nanowire ink on the nanopaper. These achievements will pave the way toward the realization of the mass production of nanofiber-based flexible devices.
Early-Life Exposure to Non-Nutritive Sweeteners and the Developmental Origins of Childhood Obesity: Global Evidence from Human and Rodent Studies
Authors: Archibald Alyssa , Dolinsky Vernon , Azad Meghan
Published: February 2018

Non-nutritive sweeteners (NNS) are increasingly consumed by children and pregnant women around the world, yet their long-term health impact is unclear. Here, we review an emerging body of evidence suggesting that early-life exposure to NNS may adversely affect body composition and cardio-metabolic health. Some observational studies suggest that children consuming NNS are at increased risk for obesity-related outcomes; however, others find no association or provide evidence of confounding. Fewer studies have examined prenatal NNS exposure, with mixed results from different analytical approaches. There is a paucity of RCTs evaluating NNS in children, yielding inconsistent results that can be difficult to interpret due to study design limitations (e.g., choice of comparator, multifaceted interventions). The majority of this research has been conducted in high-income countries. Some rodent studies demonstrate adverse metabolic effects from NNS, but most have used extreme doses that are not relevant to humans, and few have distinguished prenatal from postnatal exposure. Most studies focus on synthetic NNS in beverages, with few examining plant-derived NNS or NNS in foods. Overall, there is limited and inconsistent evidence regarding the impact of early-life NNS exposure on the developmental programming of obesity and cardio-metabolic health. Further research and mechanistic studies are needed to elucidate these effects and inform dietary recommendations for expectant mothers and children worldwide.