bluuebunny/crossref_metadata_2025 huggingface dataset:
Multifunctional Performance of a Nano-Modified Fiber Reinforced Composite Aeronautical Panel
Authors: Arena Maurizio , Viscardi Massimo , Barra Giuseppina , Vertuccio Luigi , Guadagno Liberata
Published: March 2019

The adoption of multifunctional flame-resistant composites is becoming increasingly attractive for many components of aircrafts and competition cars. Compared to conventional alloy solutions, the reduced weight and corrosion resistance are only a couple of the relevant advantages they can offer. In this paper, a carbon fiber reinforced panel (CFRP) was impregnated with an epoxy resin enhanced using a combination of 0.5 wt% of carbon nanotubes (CNTs) and 5 wt% of Glycidyl-Polyhedral Oligomeric Silsesquioxanes (GPOSS). This formulation, which is peculiar to resins with increased electrical conductivity and flame-resistance properties, has been employed for manufacturing a carbon fiber reinforced panel (CFRP) composed of eight plies through a liquid infusion technique. Vibro-acoustic tests have been performed on the panel for the characterization of the damping performance, as well the transmission loss properties related to micro-handling treatments. The spectral excitation has been provided by an acoustic source simulating the aerodynamic pressure load agent on the structure. The incorporation of multi-walled carbon nanotubes MWCNTs in the epoxy matrix determines a non-trivial improvement in the dynamic performance of the laminate. An increased damping loss factor with reference to standard CFRP laminate and also an improvement of the sound insulation parameter was found for the specific test article.
Photocatalytic Degradation of Azithromycin by Nanostructured TiO2 Film: Kinetics, Degradation Products, and Toxicity
Authors: Čizmić Mirta , Ljubas Davor , Rožman Marko , Ašperger Danijela , Ćurković Lidija , Babić Sandra
Published: March 2019

In this paper, nanostructured TiO2 film was prepared by the by sol-gel process and dip-coating technique with titanium tetraisopropoxide as a precursor. After heat treatment at 550 °C, the deposited film was characterized by means of micro-Raman spectroscopy and atomic force microscopy (AFM). It was found that the TiO2 film consisted of only the TiO2 anatase phase and showed a granular microstructure. Photocatalytic degradation of azithromycin by using sol-gel nanostructured TiO2 film was studied to define the most effective degradation process for potential use in wastewater treatment. Different factors were evaluated during photocatalysis, such as pH (3, 7, and 10), water matrix (ultrapure water and synthetic municipal waste water effluent), influence of another pharmaceutically active compound (sulfamethoxazole, one of the most often detected pharmaceutic compounds in waste waters), and radiation sources (low pressure ultraviolet (UV) mercury lamps with a UV-A and UV-C range; a light-emitting diode (LED) lamp with a radiation peak at 365 nm). The most effective degradation process was achieved with the UV-C irradiation source in matrices at pH 10. The water matrix had little effect on the photocatalytic degradation rates of azithromycin. The presence of sulfamethoxazole in the water matrix decreased the degradation rate of azithromycin, however, only in matrices with a pH level adjusted to 10. During the experiments, five azithromycin degradation products were identified and none of them showed toxic properties, suggesting effective removal of azithromycin. LED 365 nm as the irradiation source was not as effective as the UV-C lamp. Nevertheless, considering the cost, energy efficiency, and environmental aspects of the irradiation source, the LED lamp could be a “real-life” alternative.
Experimental and Numerical Investigation of Mechanical and Thermal Effects in TiNi SMA during Transformation-Induced Creep Phenomena
Authors: Dunić Vladimir , Pieczyska Elżbieta , Kowalewski Zbigniew , Matsui Ryosuke , Slavković Radovan
Published: March 2019

(1) The paper presents experimental and numerical results of the TiNi shape memory alloy (SMA) subjected to a modified program of force-controlled tensile loading. The time-dependent development of transformation strain under the constant-force conditions was investigated to describe transformation-induced creep phenomena. (2) Mechanical characteristics of the TiNi SMA were derived using a testing machine, whereas the SMA temperature changes accompanying its deformation were obtained in a contactless manner with an infrared camera. A 3D coupled thermo-mechanical numerical analysis, realized in a partitioned approach, was applied to describe the SMA mechanical and thermal responses. (3) The stress and related temperature changes demonstrated how the transformation-induced creep process started and evolved at various stages of the SMA loading. The proposed model reproduced the stress, strain and temperature changes obtained during the experiment well; the latent heat production is in correlation with the amount of the martensitic volume fraction. (4) It was demonstrated how the transformation-induced creep process occurring in the SMA under such conditions was involved in thermo-mechanical couplings and the related temperature changes.
Structured Monolithic Catalysts vs. Fixed Bed for the Oxidative Dehydrogenation of Propane
Authors: Rossetti Ilenia , Bahadori Elnaz , Tripodi Antonio , Ramis Gianguido
Published: March 2019

The deposition of V-based catalysts for the oxidative dehydrogenation of propane to propene on cordierite honeycomb monoliths was optimised as a strategy to decrease the contact time in a structured reactor with respect to a conventional fixed bed one. 10 wt% VOx supported over SiO2 or Al2O3 were used as catalysts, deposed over the monolith using silica or alumina as primer, respectively. Both the alumina supported catalyst and the bohemite primer precursor were effectively deposed by dip-coating from stable powder suspensions, whereas insufficient adhesion was obtained when loading pre-synthesised SiO2 over the cordierite. A new method based on sol-gel production of SiO2 from tetraethylortosilicate (TEOS) over the monolith surface was set up. A correlation was derived for the prevision of the amount of silica deposed depending on the amount of TEOS. Both primer and catalyst loading were optimised as for uniformity and stability of the coating and resulted 0.5–1 wt % primer and 0.15 wt % of catalyst. Activity testing confirmed the strong improvement of propene productivity by increasing the time factor (i.e. Ncm3 of flowing reactant/min gcat), which ended in a one order of magnitude increase of productivity for the honeycomb-supported samples with respect to the fixed bed configuration.
Visual Appearance of Nanocrystal-Based Luminescent Solar Concentrators
Authors: Moraitis Panagiotis , van Leeuwen Gijs , van Sark Wilfried
Published: March 2019

The luminescent solar concentrator (LSC) is a promising concept for the integration of photovoltaic (PV) generators into the building envelope. Having the form of semitransparent plates, LSCs offer a high degree of flexibility and can be used as windows or facades, as part of the of building-integrated photovoltaic (BIPV) industry. Existing performance characterizations of LSC devices focus almost exclusively on electric power generation. However, when used as window components, the transmitted spectrum can alter the color, potentially affecting the visual comfort of the occupants by altering the properties of the sunlight. In this study, eight different state-of-the-art nanocrystals are evaluated as potential candidates for LSC window luminophores, using Monte Carlo simulations. The transparency of each LSC window varies between 90% and 50%, and the color-rendering properties are assessed with respect to the color rendering index (CRI) and the correlated color temperature (CCT). It is found that luminophores with a wide absorption bandwidth in the visible spectrum can maintain a high CRI value (above 85) and CCT values close to the Planckian locus, even for high luminophore concentrations. In contrast, luminophores that only absorb partly in the visible spectrum suffer from color distortion, a situation characterized by low CCT and CRI values, even at high transmittance.
Noble Metal Composite Porous Silk Fibroin Aerogel Fibers
Authors: Mitropoulos Alexander N. , Burpo F. John , Nguyen Chi K. , Nagelli Enoch A. , Ryu Madeline Y. , Wang Jenny , Sims R. Kenneth , Woronowicz Kamil , Wickiser J. Kenneth
Published: March 2019

Nobel metal composite aerogel fibers made from flexible and porous biopolymers offer a wide range of applications, such as in catalysis and sensing, by functionalizing the nanostructure. However, producing these composite aerogels in a defined shape is challenging for many protein-based biopolymers, especially ones that are not fibrous proteins. Here, we present the synthesis of silk fibroin composite aerogel fibers up to 2 cm in length and a diameter of ~300 μm decorated with noble metal nanoparticles. Lyophilized silk fibroin dissolved in hexafluoro-2-propanol (HFIP) was cast in silicon tubes and physically crosslinked with ethanol to produce porous silk gels. Composite silk aerogel fibers with noble metals were created by equilibrating the gels in noble metal salt solutions reduced with sodium borohydride, followed by supercritical drying. These porous aerogel fibers provide a platform for incorporating noble metals into silk fibroin materials, while also providing a new method to produce porous silk fibers. Noble metal silk aerogel fibers can be used for biological sensing and energy storage applications.
Method of Optimisation for Ambient Temperature Cured Sustainable Geopolymers for 3D Printing Construction Applications
Authors: Bong Shin Hau , Nematollahi Behzad , Nazari Ali , Xia Ming , Sanjayan Jay
Published: March 2019

Since the initial introduction of geopolymers, these materials have been characterised as environmentally-friendly sustainable substitutes for ordinary Portland cement (OPC). There is a routine increase in the application of geopolymers, especially in advanced technologies. Because of its better rheological characteristics compared to OPC, geopolymers are appropriate materials for extrusion-based 3D printing technologies. This paper focuses on the optimisation of an ambient temperature cured geopolymer for 3D printing construction applications. The effects of mixture parameters, including the type of hydroxide solution (HS), the type of silicate solution (SS) and the mass ratio of SS to HS on the workability, extrudability, shape retention ability and mechanical performance of different geopolymer mixtures were investigated. Accordingly, an optimum mixture was identified for geopolymers cured at ambient temperatures. Mechanical properties of the optimised mixture, including flexural and compressive strengths, were measured in different directions with respect to the printed layers. Further, uniaxial tension tests were also conducted on the optimised mixture to measure its interlayer bond strength. The results showed that among the activators investigated, the sodium-based activator composed of sodium hydroxide and sodium silicate solutions, with a SiO2/Na2O ratio of 3.22, was the most effective activator, providing appropriate workability and extrudability, along with reasonable strength and a high shape retention ability. The acquired mechanical properties exhibited anisotropic behaviour in different testing direction. The strength of the interlayer bond was found to be adequate to avoid interfacial shear failure.
Power Flows in Compound Transmissions for Hybrid Vehicles
Authors: De Pinto Stefano , Mantriota Giacomo
Published: March 2019

Hybrid electric vehicle (HEV) traction systems are the most promising technologies being characterized by high performance, high fuel efficiency, low emissions and long operating range. Significant improvements can be achieved equipping transmissions with variable transmission ratio such as power-split transmission and a compound power-split electric continuously variable transmission (eCVT). These systems have been introduced to improve vehicle global efficiency since they can maximize the efficiency in different operating conditions. Optimal design and control of these systems leads improvements in vehicles performance and mathematical models, which support the preliminary design phase, can play a key role in this field. In this work, the internal power circulations of “four-port-mechanical-power split device are determined through a dynamic analysis.” Finally, the efficiency of the compound transmission is analytically evaluated, assuming that the overall losses are linked to the eCVT variator.
Super Connectivity of Erdős-Rényi Graphs
Authors: Shang Yilun
Published: March 2019

The super connectivity κ ′ ( G ) of a graph G is the minimum cardinality of vertices, if any, whose deletion results in a disconnected graph that contains no isolated vertex. G is said to be r-super connected if κ ′ ( G ) ≥ r . In this note, we establish some asymptotic almost sure results on r-super connectedness for classical Erdős–Rényi random graphs as the number of nodes tends to infinity. The known results for r-connectedness are extended to r-super connectedness by pairing off vertices and estimating the probability of disconnecting the graph that one gets by identifying the two vertices of each pair.
Traveling Wave Solutions of a Delayed Cooperative System
Authors: Li Xue-Shi , Pan Shuxia
Published: March 2019

This paper deals with the dynamics of a delayed cooperative system without quasimonotonicity. Using the contracting rectangles, we obtain a sufficient condition on the stability of the unique positive steady state of the functional differential system. When the spatial domain is whole R , the existence and nonexistence of traveling wave solutions are investigated, during which the asymptotic behavior is investigated by the contracting rectangles.
Variational Inequalities Approaches to Minimization Problems with Constraints of Generalized Mixed Equilibria and Variational Inclusions
Authors: Ceng Lu-Chuan , Postolache Mihai , Wen Ching-Feng , Yao Yonghong
Published: March 2019

Multistep composite implicit and explicit extragradient-like schemes are presented for solving the minimization problem with the constraints of variational inclusions and generalized mixed equilibrium problems. Strong convergence results of introduced schemes are given under suitable control conditions.
Line Integral Solution of Hamiltonian PDEs
Authors: Brugnano Luigi , Frasca-Caccia Gianluca , Iavernaro Felice
Published: March 2019

In this paper, we report on recent findings in the numerical solution of Hamiltonian Partial Differential Equations (PDEs) by using energy-conserving line integral methods in the Hamiltonian Boundary Value Methods (HBVMs) class. In particular, we consider the semilinear wave equation, the nonlinear Schrödinger equation, and the Korteweg–de Vries equation, to illustrate the main features of this novel approach.
Variational Approaches for Lagrangian Discrete Nonlinear Systems
Authors: Alkhalidi Ahmed A. H. , Afrouzi Ghasem A. , Khademloo Somayeh
Published: March 2019

In this paper, we study the multiple solutions for Lagrangian systems of discrete second-order boundary value systems involving the discrete p-Laplacian operator. The technical approaches are based on a local minimum theorem for differentiable functionals in a finite dimensional space and variational methods due to Bonanno. The existence of at least one solution, as well as three solutions for the given system are discussed and some examples and remarks have also been given to illustrate the main results.
Hydrophilic Glycoproteins of an Edible Green Alga Capsosiphon fulvescens Prevent Aging-Induced Spatial Memory Impairment by Suppressing GSK-3β-Mediated ER Stress in Dorsal Hippocampus
Authors: Oh Jeong Hwan , Nam Taek-Jeong
Published: March 2019

Endoplasmic reticulum (ER) stress is involved in various neurodegenerative disorders. We previously found that Capsosiphon fulvescens (C. fulvescens) crude proteins enhance spatial memory by increasing the expression of brain-derived neurotrophic factor (BDNF) in rat dorsal hippocampus. The present study investigated whether the chronic oral administration of hydrophilic C. fulvescens glycoproteins (Cf-hGP) reduces aging-induced cognitive dysfunction by regulating ER stress in the dorsal hippocampus. The oral administration of Cf-hGP (15 mg/kg/day) for four weeks attenuated the aging-induced increase in ER stress response protein glucose-regulated protein 78 (GRP78) in the synaptosome of the dorsal hippocampus; this was attenuated by the function-blocking anti-BDNF antibody (1 μg/μL) and a matrix metallopeptidase 9 inhibitor 1 (5 μM). Aging-induced GRP78 expression was associated with glycogen synthase kinase-3 beta (GSK-3β) (Tyr216)-mediated c-Jun N-terminal kinase phosphorylation, which was downregulated upon Cf-hGP administration. The Cf-hGP-induced increase in GSK-3β (Ser9) phosphorylation was downregulated by inhibiting tyrosine receptor kinase B and extracellular signal-regulated kinase (ERK)1/2 with cyclotraxin-B (200 nM) and SL327 (10 μM), respectively. Cf-hGP administration or the inhibition of ER stress with salubrinal (1 mg/kg, i.p.) significantly decreased aging-induced spatial memory impairment. These findings suggest that the activation of the synaptosomal BDNF-ERK1/2 signaling in the dorsal hippocampus by Cf-hGP attenuates age-dependent ER stress-induced cognitive dysfunction.
A Multi-screening Evaluation of the Nutritional and Nutraceutical Potential of the Mediterranean Jellyfish Pelagia noctiluca
Authors: Costa Rosaria , Capillo Gioele , Albergamo Ambrogina , Li Volsi Rosalia , Bartolomeo Giovanni , Bua Giuseppe , Ferracane Antonio , Savoca Serena , Gervasi Teresa , Rando Rossana , Dugo Giacomo , Spanò Nunziacarla
Published: March 2019

The phylum Cnidaria is one of the most important contributors in providing abundance of bio- and chemodiversity. In this study, a comprehensive chemical investigation on the nutritional and nutraceutical properties of Mediterranean jellyfish Pelagia noctiluca was carried out. Also, compositional differences between male and female organisms, as well as between their main anatomical parts, namely bell and oral arms, were explored in an attempt to select the best potential sources of nutrients and/or nutraceuticals from jellyfish. With the exception of higher energy densities and total phenolic contents observed in females than males, no statistically significant differences related to the specimen’s sex were highlighted for the other compound classes. Rather, the distribution of the investigated chemical classes varied depending on the jellyfish’s body parts. In fact, crude proteins were more abundant in oral arms than bells; saturated fatty acids were more concentrated in bells than oral arms, whereas polyunsaturated fatty acids were distributed in the exact opposite way. On the other hand, major elements and trace elements demonstrated an opposite behavior, being the latter most accumulated in oral arms than bells. Additionally, important nutraceuticals, such as eicosapentaenoic and docosahexaenoic acids, and antioxidant minerals, were determined. Overall, obtained data suggest the potential employment of the Mediterranean P. noctiluca for the development of natural aquafeed and food supplements.
Dietary Supplementation with Low-Molecular-Weight Fucoidan Enhances Innate and Adaptive Immune Responses and Protects against Mycoplasma pneumoniae Antigen Stimulation
Authors: Hwang Pai-An , Lin Hong-Ting Victor , Lin Hsin-Yuan , Lo Szu-Kuan
Published: March 2019

In this study, the low-molecular-weight (LMW) fucoidan, rich in fucose and sulfate, was extracted and purified from the edible brown seaweed, Laminaria japonica. In this study, we orally administered LMW fucoidan to mice for 6 weeks. We then examined fucoidan’s effects on innate immunity, adaptive immunity, and Mycoplasma pneumoniae (MP)-antigen-stimulated immune responses. Our data showed that LMW fucoidan stimulated the innate immune system by increasing splenocyte proliferation, natural killer (NK) cell activity, and phagocytic activity. LMW fucoidan also increased interleukin (IL)-2, IL-4, and interferon (IFN)-γ secretion by splenocytes and immunoglobulin (Ig)-G and IgA content in serum, which help regulate adaptive immune cell functions, and decreased allergen-specific IgE. In MP-antigen-stimulated immune responses, the IgM and IgG content in the serum were significantly higher in the LMW fucoidan group after MP-antigen stimulation. Our study provides further information about the immunomodulatory effects of LMW fucoidan and highlights a potential role in preventing M. pneumoniae infection.
Aspirin Exacerbated Respiratory Disease: Epidemiology, Pathophysiology, and Management
Authors: Li Kevin L. , Lee Andrew Y. , Abuzeid Waleed M.
Published: March 2019

The correlation between aspirin sensitivity, asthma, and nasal polyposis was recognized in the early 20th century. Today, this classic triad of symptoms, eponymously named Samter’s Triad, is known as aspirin exacerbated respiratory disease (AERD). Aspirin exacerbated respiratory disease affects approximately 0.3–0.9% of the general population in the USA and approximately 7% of asthmatic patients. The management of AERD is challenging as no single modality has proven to have high rates of symptom control. Consequently, disease management typically involves a multimodality approach across both medical and surgical disciplines. This review describes the epidemiology of AERD and the current state-of-the-art as it relates to the underlying pathophysiologic mechanisms of this disease process. A significant proportion of the review is focused on the appropriate diagnostic workup for AERD patients including the utility of aspirin provocation testing. The spectrum of medical treatments, including aspirin desensitization and recently introduced immunotherapies, are discussed in detail. Furthermore, surgical approaches to disease control, including advanced endoscopic techniques, are reviewed and treatment outcomes presented.
Real-World Experiences with Pazopanib in Patients with Advanced Soft Tissue and Bone Sarcoma in Northern California
Authors: Seto Tiffany , Song Mee-Na , Trieu Maily , Yu Jeanette , Sidhu Manpreet , Liu Chi-Mei , Sam Danny , Pan Minggui
Published: March 2019

Background: Pazopanib was approved for advanced soft tissue sarcoma as a second- or third-line therapy based on the clinical trial “Pazopanib for metastatic soft-tissue sarcoma” (PALETTE). We hypothesized that the real-world experiences may be significantly different from the clinical trial results. Methods: We analyzed the response pattern of patients with advanced soft tissue and bone sarcoma who received pazopanib treatment between 1 January 2011 and 31 October 2018 in Kaiser Permanente Northern California. Results: A total of 123 patients with 23 different histologic subtypes were assessable. One patient with low-grade fibromyxoid sarcoma obtained complete response (CR) after 2 months of treatment with pazopanib, 12 patients (9.7%) obtained partial response (PR), 34 patients (27.6%) had stable disease (SD), while 76 patients (61.8%) developed progressive disease (PD). The disease control rate (DCR) was 46.3% (CR + PR + SD). Among the 12 patients with PR, 3 had undifferentiated pleomorphic sarcoma (UPS), 4 had leiomyosarcoma (LMS), 2 had pleomorphic rhabdomyosarcoma, 1 had pleomorphic liposarcoma, 1 had dedifferentiated liposarcoma, and 1 had angiosarcoma. The median duration of response was 9 months. Two patients with Ewing’s sarcoma had SD for 6 and 13 months, and two patients with osteosarcoma had SD for 6 and 9 months. Among 65 patients assessed at 8 weeks, 9 had a response, and 10 had SD. Among 104 patients assessed at 12 weeks, 12 had a response, and 26 had SD. The median progression-free survival (PFS) was approximately 3 months for all 123 cases and for patients with UPS and LMS. Conclusions: Our cohort of patients with advanced soft tissue and bone sarcoma in Northern California treated with pazopanib had diverse histologic subtypes. The response rate (CR + PR) was higher than that of the PALETTE trial, while the DCR and the median PFS were significantly lower. The observation of PR in two patients with liposarcoma and durable SD in several patients with bone sarcoma indicates that pazopanib has activity in liposarcoma and bone sarcoma.
Analysis of Powder Binder Separation through Multiscale Computed Tomography
Authors: Yang Shidi , Xu Qiaoli , Liu Chengcheng , Lu Xin , Qu Xuanhui , Xu Ying
Published: March 2019

In this study, X-ray computed tomography was used to analyze powder binder separation in TC4 green bodies. Firstly, for the scanned results of the whole green body, because of the relative low resolution (36 µm), the powder binder separation can only be analyzed by using gray value distribution. Then, local regions (areas near the gate and the central parts) were scanned by using a much higher resolution (2.3 µm). Both of the volume fraction of powder content and gray value distributions indicate that powder particles tend to accumulate in the central parts. Finally, based on the results tested by using submicron resolution (0.8 µm), the effects of the volume and morphology of the powder particles on the powder binder separation were analyzed.
Investigation of the Temperature-Related Wear Performance of Hard Nanostructured Coatings Deposited on a S600 High Speed Steel
Authors: Santecchia Eleonora , Cabibbo Marcello , Hamouda Abdel Magid Salem , Musharavati Farayi , Popelka Anton , Spigarelli Stefano
Published: March 2019

Thin hard coatings are widely known as key elements in many industrial fields, from equipment for metal machining to dental implants and orthopedic prosthesis. When it comes to machining and cutting tools, thin hard coatings are crucial for decreasing the coefficient of friction (COF) and for protecting tools against oxidation. The aim of this work was to evaluate the tribological performance of two commercially available thin hard coatings deposited by physical vapor deposition (PVD) on a high speed tool steel (S600) under extreme working conditions. For this purpose, pin-on-disc wear tests were carried out either at room temperature (293 K) or at high temperature (873 K) against alumina (Al2O3) balls. Two thin hard nitrogen-rich coatings were considered: a multilayer AlTiCrN and a superlattice (nanolayered) CrN/NbN. The surface and microstructure characterization were performed by optical profilometry, field-emission gun scanning electron microscopy (FEGSEM), and energy dispersive spectroscopy (EDS).
The Influence of Heat Treatment Parameters on the Cracks Growth under Cyclic Bending in St-Ti Clad Obtained by Explosive Welding
Authors: Rozumek Dariusz , Kwiatkowski Grzegorz
Published: March 2019

The current work focuses on the effect of time and temperature of annealing on the change in the structure and cracks growth and fatigue life of the steel-titanium bimetal obtained by explosive welding. Cyclic bending tests were performed for different levels of annealing temperature on bimetal specimens of a rectangular cross-section. The fatigue crack growth was measured by microscopy. Structure changes of steel, titanium and bond area resulted in a different micro-hardness distribution. The relationship between the level of the annealing temperature, the propagation of fatigue cracks, structure changes and micro-hardness level is analyzed. The heat treatment of the bimetal at the temperature of 500 °C does not result in considerable changes in the structure of steel and titanium. The diffusion of carbon to titanium was observed. A higher annealing temperature results in a lower fatigue life. Also, for a given annealing temperature, a longer annealing time results in a higher fatigue life.
Multiscale Comparison Study of Void Closure Law and Mechanism in the Bimetal Roll-Bonding Process
Authors: Zhang Qingdong , Li Shuo , Li Rui , Zhang Boyang
Published: March 2019

The void closure mechanism during the roll-bonding process was investigated using a multiscale approach, which includes contact deformation at the macro-scale and atomic bonding at the micro-scale. The closure process of the voids was observed using roll-bonding tests of 304 stainless steel/Q235 carbon steel. A finite element model was built to simulate the macroscopic deformation process of 304/Q235 material, and a molecular dynamics model established to simulate the deformation process of the microscopic rough peaks. The closure law and mechanism of interface voids at the macro- and micro-scales were studied. The results show that the closure rate of interface voids decreases with the decrease in the average contact stress during the contact deformation process. In the atomic bonding process, the void closure rate is slow in the elastic deformation process. The ordered atoms near the interface become disordered as plastic deformation occurs, which increases the void closure rate and hinders dislocation propagation through the interface, resulting in significant strengthening effects via plastic deformation. Ultimately, a perfect lattice is reconstructed with void healing. In addition, the interface morphology after roll-bonding at the macro scale was determined by the morphology of the 304 steel with larger yield strength ratio, while the interface morphology at the micro-scale was mainly determined by the morphology of the Q235 steel with a higher yield strength.
Strain-Rate-Dependent Deformation Behavior and Mechanical Properties of a Multi-Phase Medium-Manganese Steel
Authors: Sevsek Simon , Haase Christian , Bleck Wolfgang
Published: March 2019

The strain-rate-dependent deformation behavior of an intercritically annealed X6MnAl12-3 medium-manganese steel was analyzed with respect to the mechanical properties, activation of deformation-induced martensitic phase transformation, and strain localization behavior. Intercritical annealing at 675 °C for 2 h led to an ultrafine-grained multi-phase microstructure with 45% of mostly equiaxed, recrystallized austenite and 55% ferrite or recovered, lamellar martensite. In-situ digital image correlation methods during tensile tests revealed strain localization behavior during the discontinuous elastic-plastic transition, which was due to the localization of strain in the softer austenite in the early stages of plastic deformation. The dependence of the macroscopic mechanical properties on the strain rate is due to the strain-rate sensitivity of the microscopic deformation behavior. On the one hand, the deformation-induced phase transformation of austenite to martensite showed a clear strain-rate dependency and was partially suppressed at very low and very high strain rates. On the other hand, the strain-rate-dependent relative strength of ferrite and martensite compared to austenite influenced the strain partitioning during plastic deformation, and subsequently, the work-hardening rate. As a result, the tested X6MnAl12-3 medium-manganese steel showed a negative strain-rate sensitivity at very low to medium strain rates and a positive strain-rate sensitivity at medium to high strain rates.
PLS2 in Metabolomics
Authors: Stocchero Matteo , Locci Emanuela , d’Aloja Ernesto , Nioi Matteo , Baraldi Eugenio , Giordano Giuseppe
Published: March 2019

Metabolomics is the systematic study of the small-molecule profiles of biological samples produced by specific cellular processes. The high-throughput technologies used in metabolomic investigations generate datasets where variables are strongly correlated and redundancy is present in the data. Discovering the hidden information is a challenge, and suitable approaches for data analysis must be employed. Projection to latent structures regression (PLS) has successfully solved a large number of problems, from multivariate calibration to classification, becoming a basic tool of metabolomics. PLS2 is the most used implementation of PLS. Despite its success, PLS2 showed some limitations when the so called ‘structured noise’ affects the data. Suitable methods have been recently introduced to patch up these limitations. In this study, a comprehensive and up-to-date presentation of PLS2 focused on metabolomics is provided. After a brief discussion of the mathematical framework of PLS2, the post-transformation procedure is introduced as a basic tool for model interpretation. Orthogonally-constrained PLS2 is presented as strategy to include constraints in the model according to the experimental design. Two experimental datasets are investigated to show how PLS2 and its improvements work in practice.
Critical Review of Volatile Organic Compound Analysis in Breath and In Vitro Cell Culture for Detection of Lung Cancer
Authors: Jia Zhunan , Patra Abhijeet , Kutty Viknish Krishnan , Venkatesan Thirumalai
Published: March 2019

Breath analysis is a promising technique for lung cancer screening. Despite the rapid development of breathomics in the last four decades, no consistent, robust, and validated volatile organic compound (VOC) signature for lung cancer has been identified. This review summarizes the identified VOC biomarkers from both exhaled breath analysis and in vitro cultured lung cell lines. Both clinical and in vitro studies have produced inconsistent, and even contradictory, results. Methodological issues that lead to these inconsistencies are reviewed and discussed in detail. Recommendations on addressing specific issues for more accurate biomarker studies have also been made.
Design and Evaluation of a Novel Hybrid Soft Surgical Gripper for Safe Digital Nerve Manipulation
Authors: Guo Jin , Low Jin-Huat , Wong Yoke-Rung , Yeow Chen-Hua
Published: March 2019

Forceps are essential tools for digital nerve manipulation during digital nerve repair surgery. However, surgeons have to operate forceps with extreme caution to prevent detrimental post-operative complications caused by over-gripping force. Their intrinsically safe characteristics have led to the increasing adoption of soft robotics in various biomedical applications. In this paper, a miniaturized hybrid soft surgical gripper is proposed for safe nerve manipulation in digital nerve repair surgery. This new surgical gripper includes a soft inflatable actuator and a gripper shell with a hook-shaped structure. The ability to achieve a compliant grip and safe interaction with digital nerves is provided by the inflated soft pneumatic actuator, while the rigid hook retractor still allows surgeons to scoop up the nerve from its surrounding tissues during surgery. The performance of the proposed surgical gripper was evaluated by the contact/pulling force sensing experiments and deformation measurement experiments. In the cadaver experiments, this new surgical gripper was able to complete the required nerve manipulation within the limited working space. The average deformation of the digital nerve with an average diameter of 1.45 mm gripped by the proposed surgical gripper is less than 0.22 mm. The average deformity is less than 15% of its original diameter.
Supercoil Levels in E. coli and Salmonella Chromosomes Are Regulated by the C-Terminal 35–38 Amino Acids of GyrA
Authors: Rovinskiy Nikolay S. , Agbleke Andrews A. , Chesnokova Olga N. , Higgins N. Patrick
Published: March 2019

Prokaryotes have an essential gene—gyrase—that catalyzes negative supercoiling of plasmid and chromosomal DNA. Negative supercoils influence DNA replication, transcription, homologous recombination, site-specific recombination, genetic transposition and sister chromosome segregation. Although E. coli and Salmonella Typhimurium are close relatives with a conserved set of essential genes, E. coli DNA has a supercoil density 15% higher than Salmonella, and E. coli cannot grow at the supercoil density maintained by wild type (WT) Salmonella. E. coli is addicted to high supercoiling levels for efficient chromosomal folding. In vitro experiments were performed with four gyrase isoforms of the tetrameric enzyme (GyrA2:GyrB2). E. coli gyrase was more processive and faster than the Salmonella enzyme, but Salmonella strains with chromosomal swaps of E. coli GyrA lost 40% of the chromosomal supercoil density. Reciprocal experiments in E. coli showed chromosomal dysfunction for strains harboring Salmonella GyrA. One GyrA segment responsible for dis-regulation was uncovered by constructing and testing GyrA chimeras in vivo. The six pinwheel elements and the C-terminal 35–38 acidic residues of GyrA controlled WT chromosome-wide supercoiling density in both species. A model of enzyme processivity modulated by competition between DNA and the GyrA acidic tail for access to β-pinwheel elements is presented.
Variovorax sp. Has an Optimum Cell Density to Fully Function as a Plant Growth Promoter
Authors: Natsagdorj Oyungerel , Sakamoto Hisayo , Santiago Dennis Marvin O. , Santiago Christine D. , Orikasa Yoshitake , Okazaki Kazuyuki , Ikeda Seishi , Ohwada Takuji
Published: March 2019

Utilization of plant growth-promoting bacteria colonizing roots is environmentally friendly technology instead of using chemicals in agriculture, and understanding of the effects of their colonization modes in promoting plant growth is important for sustainable agriculture. We herein screened the six potential plant growth-promoting bacteria isolated from Beta vulgaris L. (Rhizobium sp. HRRK 005, Polaromonas sp. HRRK 103, Variovorax sp. HRRK 170, Mesorhizobium sp. HRRK 190, Streptomyces sp. HRTK 192, and Novosphingobium sp. HRRK 193) using a series of biochemical tests. Among all strains screened, HRRK 170 had the highest potential for plant growth promotion, given its ability to produce plant growth substances and enzymes such as siderophores and 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, respectively, concomitantly with active growth in a wider range of temperatures (10–30 °C) and pH (5.0–10.0). HRRK 170 colonized either as spots or widely on the root surface of all vegetable seedlings tested, but significant growth promotion occurred only in two vegetables (Chinese cabbage and green pepper) within a certain cell density range localized in the plant roots. The results indicate that HRRK 170 could function as a plant growth promoter, but has an optimum cell density for efficient use.
The Production and Delivery of Probiotics: A Review of a Practical Approach
Authors: Fenster Kurt , Freeburg Barbara , Hollard Chris , Wong Connie , Rønhave Laursen Rune , Ouwehand Arthur C.
Published: March 2019

To successfully deliver probiotic benefits to the consumer, several criteria must be met. Here, we discuss the often-forgotten challenges in manufacturing the strains and incorporating them in consumer products that provide the required dose at the end of shelf life. For manufacturing, an intricate production process is required that ensures both high yield and stability and must also be able to meet requirements such as the absence of specific allergens, which precludes some obvious culture media ingredients. Reproducibility is important to ensure constant high performance and quality. To ensure this, quality control throughout the whole production process, from raw materials to the final product, is essential, as is the documentation of this quality control. Consumer product formulation requires extensive skill and experience. Traditionally, probiotic lactic acid bacteria and bifidobacteria have been incorporated in fermented dairy products, with limited shelf life and refrigerated storage. Currently, probiotics may be incorporated in dietary supplements and other “dry” food matrices which are expected to have up to 24 months of stability at ambient temperature and humidity. With the right choice of production process, product formulation, and strains, high-quality probiotics can be successfully included in a wide variety of delivery formats to suit consumer requirements.
X-ray Microcomputed Tomography (µCT) for Mineral Characterization: A Review of Data Analysis Methods
Authors: Guntoro Pratama , Ghorbani Yousef , Koch Pierre-Henri , Rosenkranz Jan
Published: March 2019

The main advantage of X-ray microcomputed tomography (µCT) as a non-destructive imaging tool lies in its ability to analyze the three-dimensional (3D) interior of a sample, therefore eliminating the stereological error exhibited in conventional two-dimensional (2D) image analysis. Coupled with the correct data analysis methods, µCT allows extraction of textural and mineralogical information from ore samples. This study provides a comprehensive overview on the available and potentially useful data analysis methods for processing 3D datasets acquired with laboratory µCT systems. Our study indicates that there is a rapid development of new techniques and algorithms capable of processing µCT datasets, but application of such techniques is often sample-specific. Several methods that have been successfully implemented for other similar materials (soils, aggregates, rocks) were also found to have the potential to be applied in mineral characterization. The main challenge in establishing a µCT system as a mineral characterization tool lies in the computational expenses of processing the large 3D dataset. Additionally, since most of the µCT dataset is based on the attenuation of the minerals, the presence of minerals with similar attenuations limits the capability of µCT in mineral segmentation. Further development on the data processing workflow is needed to accelerate the breakthrough of µCT as an analytical tool in mineral characterization.
Why RGB Imaging Should be Used to Analyze Fusarium Graminearum Growth and Estimate Deoxynivalenol Contamination
Authors: Cambaza Edgar , Koseki Shigenobu , Kawamura Shuso
Published: March 2019

Size-based fungal growth studies are limited because they do not provide information about the mold’s state of maturity, and measurements such as radius and diameter are not practical if the fungus grows irregularly. Furthermore, the current methods used to detect diseases such as Fusarium head blight (FHB) or mycotoxin contamination are labor-intensive and time consuming. FHB is frequently detected through visual examination and the results can be subjective, depending on the skills and experience of the analyzer. For toxin determination (e.g., deoxynivalenol (DON), the best methods are expensive, not practical for routine. RGB (red, green and blue) imaging analysis is a viable alternative that is inexpensive, easy to use and seemingly better if enhanced with statistical methods. This short communication explains why RGB imaging analysis should be used instead of size-based variables as a tool to measure growth of Fusarium graminearum and DON concentration.
Low-Cost and High-Performance ZnO Nanoclusters Gas Sensor Based on New-Type FTO Electrode for the Low-Concentration H2S Gas Detection
Authors: Zhao Guodong , Xuan Jingyue , Liu Xiaolin , Jia Fuchao , Sun Yuping , Sun Meiling , Yin Guangchao , Liu Bo
Published: March 2019

A low-cost and high-performance gas sensor was fabricated by the in-situ growing of ZnO nanoclusters (NCs) arrays on the etched fluorine-doped tin dioxide (FTO) glass via a facile dip-coating and hydrothermal method. Etched FTO glass was used as a new-type gas-sensing electrode due to its advantages of being low cost and having excellent thermal and chemical stability. ZnO NCs are composed of multiple ZnO nanorods and can provide adequate lateral contacts to constitute the paths required for the gas-sensing tests simultaneously, which can provide many advantageous point junctions for the detection of low-concentration gases. The gas-sensing tests indicate that the ZnO NCs gas sensor has good selectivity and a high response for the low-concentration H2S gas. The sensing response has reached 3.3 for 500 ppb H2S at 330 °C. The excellent gas-sensing performances should be attributed to the large specific surface area of in-situ grown ZnO NCs, the perfect ohmic contact between ZnO NCs and FTO electrode and the variation of grain boundary barrier at the cross-linked junctions of multiple nanorods. In addition, the detailed effect of work temperature and gas concentration on gas-sensing, the stability of gas sensors and the corresponding response mechanism are also discussed in the present paper.
Growth of CaxCoO2 Thin Films by A Two-Stage Phase Transformation from CaO–CoO Thin Films Deposited by Rf-Magnetron Reactive Cosputtering
Authors: Paul Biplab , Lu Jun , Eklund Per
Published: March 2019

The layered cobaltates AxCoO2 (A: alkali metals and alkaline earth metals) are of interest in the area of energy harvesting and electronic applications, due to their good electronic and thermoelectric properties. However, their future widespread applicability depends on the simplicity and cost of the growth technique. Here, we have investigated the sputtering/annealing technique for the growth of CaxCoO2 (x = 0.33) thin films. In this approach, CaO–CoO film is first deposited by rf-magnetron reactive cosputtering from metallic targets of Ca and Co. Second, the as-deposited film is reactively annealed under O2 gas flow to form the final phase of CaxCoO2. The advantage of the present technique is that, unlike conventional sputtering from oxide targets, the sputtering is done from the metallic targets of Ca and Co; thus, the deposition rate is high. Furthermore, the composition of the film is controllable by controlling the power at the targets.
Characterization of Vertically Aligned Carbon Nanotube Forests Grown on Stainless Steel Surfaces
Authors: Roumeli Eleftheria , Diamantopoulou Marianna , Serra-Garcia Marc , Johanns Paul , Parcianello Giulio , Daraio Chiara
Published: March 2019

Vertically aligned carbon nanotube (CNT) forests are a particularly interesting class of nanomaterials, because they combine multifunctional properties, such as high energy absorption, compressive strength, recoverability, and super-hydrophobicity with light weight. These characteristics make them suitable for application as coating, protective layers, and antifouling substrates for metallic pipelines and blades. Direct growth of CNT forests on metals offers the possibility of transferring the tunable CNT functionalities directly onto the desired substrates. Here, we focus on characterizing the structure and mechanical properties, as well as wettability and adhesion, of CNT forests grown on different types of stainless steel. We investigate the correlations between composition and morphology of the steel substrates with the micro-structure of the CNTs and reveal how the latter ultimately controls the mechanical and wetting properties of the CNT forest. Additionally, we study the influence of substrate morphology on the adhesion of CNTs to their substrate. We highlight that the same structure-property relationships govern the mechanical performance of CNT forests grown on steels and on Si.
Synthesis, Characterization, and Antibacterial Activity of Ag2O-Loaded Polyethylene Terephthalate Fabric via Ultrasonic Method
Authors: Rajabi Armin , Ghazali Mariyam Jameelah , Mahmoudi Ebrahim , Baghdadi Amir Hossein , Mohammad Abdul Wahab , Mustafah Nadia Mohd , Ohnmar Htwe , Naicker Amaramalar Selvi
Published: March 2019

In this study, Ag2O was synthesized on polyethylene terephthalate fabrics by using an ultrasonic technique with Ag ion reduction in an aqueous solution. The effects of pH on the microstructure and antibacterial properties of the fabrics were evaluated. X-ray diffraction confirmed the presence of Ag2O on the fabrics. The fabrics were characterized by Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, and wettability testing. Field-emission scanning electron microscopy verified that the change of pH altered the microstructure of the materials. Moreover, the antibacterial activity of the fabrics against Escherichia coli was related to the morphology of Ag2O particles. Thus, the surface structure of Ag2O particles may be a key factor of the antibacterial activity.