bluuebunny/crossref_metadata_2025 huggingface dataset:
The Mix Ratio Study of Self-Stressed Anti-Washout Underwater Concrete Used in Nondrainage Strengthening
Authors: Wu Shaofeng , Jiang Shao-Fei , Shen Sheng , Wu Zhaoqi
Published: January 2019

Anti-washout underwater concrete (AWC) is widely used in nondrainage strengthening; however, there still exist some problems with it, such as high strength loss and poor interfacial bond in practical engineering application. Based on the study of self-stressed concrete (SSC), a research on the mix ratio for the C30 self-stressed anti-washout underwater concrete (SSAWC) was carried out in this paper in hope of solving the above problems, specifically, by adding an expansive agent to the AWC. The parameters, such as strength, fluidity, anti-dispersity, and expansibility, were picked as target indices in determination of the mix ratio. The orthogonal test design and range analysis were used to determine the reasonable mix ratio and study the influence of various parameters on the performance of SSAWC. The experimental program conducted includes a series of strength, fluidity, anti-dispersity, and expansibility tests on 18 groups of specimens. The results show that C30 SSAWC has an excellent performance using the optimal mix ratio. Compared with AWC, the expansibility and self-stress of the SSAWC can be easily observed, and the compressive strength ratio of the SSAWC casted in water to that casted in air is much bigger. This implies that SSAWC is applicable to the nondrainage strengthening.
Nonlinear Resonance Vibration Assessment to Evaluate the Freezing and Thawing Resistance of Concrete
Authors: Kim Jae Hong , Park Sun-Jong , Yim Hong Jae
Published: January 2019

Under cold environments, the freezing and thawing cycles of water in concrete reduce the lifetime and durability of concrete structures. For enhanced freezing and thawing resistance, entrained air voids are generally required, but malfunctioning of air entrainment is sometimes reported in the field. To evaluate the quality of air entrainment, this study proposes a nondestructive method that is a preceding evaluation before damage to the concrete. A nonlinear resonance vibration method is adopted in samples having an identical air void content. The durable concrete sample with resistance to freezing and thawing cycles shows higher nonlinearity in its resonance. Thus, the quality of air entrainment and, furthermore, the potential freezing and thawing resistance can possibly be evaluated by measuring the nonlinearity parameter of the concrete, which is preliminary study to attempt the preceding evaluation of freezing and thawing resistance using nondestructive method.
Properties of Cement-Based Composites Modified with Magnetite Nanoparticles: A Review
Authors: Horszczaruk Elżbieta
Published: January 2019

Despite the many available studies on the evaluation of the influence of nanomaterials on the properties of cement-based composites, the effects of some nanoparticles have not yet been fully recognized. Among the unrecognized nanomaterials are magnetite nanoparticles (MN). The literature devoted to this subject is limited. This paper reviews state-of-the-art research carried out on the effect of MN on the properties of cement-based composites. Detailed descriptions of the processing, microstructures (hydration products), properties (hydration, workability, mechanical and functional properties, and durability), and probability applications of MN-engineered cementitious composites are presented. Particular attention has been paid to MN application methods to the cement composite. Finally, the risks, challenges, and future development of MN-modified cement-based composites is discussed.
Stimuli-Responsive Systems in Optical Humidity-Detection Devices
Authors: Calixto Sergio , Piazza Valeria , Marañon-Ruiz Virginia
Published: January 2019

The use of electronic devices to measure Relative Humidity (RH) is widespread. However, under certain circumstances, for example when explosive gases are present, a spark-free method should be used. Here we suggest the use of stimuli-responsive materials, like gelatin and interpenetrated polymers, to detect RH with an optical method. These materials are hydrophilic. When water vapor is absorbed by the films the molecules attach to the films molecular network. The result is that the film thickness increases and their refractive index changes. To detect the change of these two parameters an optical method based on diffraction gratings is employed. Surface diffraction gratings are recorded on the films. Then gratings are placed in an optical configuration that is immersed in a climatic chamber. A light beam is sent to the grating where it is diffracted. Several light orders appear. Due to the absorption of water molecules the films swell and grating surface modulation changes. This implies that the diffracted orders intensity changes. A calibrating plot relating intensity as a function of RH is obtained.
Effect of Fibers on High-Temperature Mechanical Behavior and Microstructure of Reactive Powder Concrete
Authors: Abid Muhammad , Hou Xiaomeng , Zheng Wenzhong , Hussain Raja Rizwan
Published: January 2019

This study was aimed to investigate the effect of steel, polypropylene (PP), and hybrid (steel + PP) fibers on high-temperature mechanical properties of reactive powder concrete (RPC). The mechanical properties considered are cubic compressive strength, axial or prismatic compressive strength, split-tensile strength, flexural strength, elastic modulus, peak strain, and stress-strain behavior. The strength recession due to high temperature was investigated at micro level by scanning electron microscope, energy dispersive X-ray spectroscopy, X-ray diffraction, mercury intrusion porosity, thermogravimetric, and differential scanning calorimetry analyses. The high-temperature tests were carried out at target temperatures of 120, 300, 500, 700, and 900 °C. The hot-state compressive strength of RPC started to decrease at 120 °C; however, a partial recovery at 300 °C and a gradual decrease above 300 °C were observed. The degradation of split-tensile strength, flexural strength, and elastic modulus were gradual with increasing temperature despite the effect of different fibers. Whereas, the peak strain was gradually increasing up to 700 °C. However, after 700 °C, it remained unchanged. Steel fiber reinforced RPC (SRPC) and hybrid fiber reinforced RPC (HRPC) showed a ductile behavior. PP fiber reinforced RPC (PRPC) showed a quite brittle behavior up to 300 °C; however, further heating made the microstructure porous and it became ductile too. Overall the performance of SRPC and HRPC were superior to PRPC because of higher modulus of elasticity, higher strength, and better fire resistance of steel fibers. Fiber reinforced RPC was found to have better fire resistance than traditional types of concrete based on comparative studies with the provisions of design codes and earlier research. The constitutive equations developed can be utilized in computer programs for structural design of RPC structures exposed to fire.
The Reaction Thermodynamics during Plating Al on Graphene Process
Authors: Zhao Zhanyong , Bai Peikang , Li Liang , Li Jing , Wu Liyun , Huo Pengcheng , Tan Le
Published: January 2019

This research explored a novel chemical reduction of organic aluminum for plating Al on a graphene surface. The thermodynamics of the Al plating reaction process were studied. The Al plating process consisted of two stages: the first was to prepare (C2H5)3Al. In this reaction, the ΔH(enthalpy) was 10.64 kcal/mol, the ΔG(Gibbs free energy) was 19.87 kcal/mol and the ΔS(entropy) was 30.9 cal/(mol·K); this was an endothermic reaction. In the second stage, the (C2H5)3Al decomposed into Al atoms, which were gradually deposited on the surface of the graphene and the Al plating formed. At 298.15 K, the ΔH was −20.21 kcal/mol, the ΔG was −54.822 kcal/mol, the ΔS was 116.08 cal/(mol·K) and the enthalpy change was negative, thus indicating an endothermic reaction.
The Characterization of Affine Symplectic Curves in ℝ4
Authors: Çiçek Çetin Esra , Bektaş Mehmet
Published: January 2019

Symplectic geometry arises as the natural geometry of phase-space in the equations of classical mechanics. In this study, we obtain new characterizations of regular symplectic curves with respect to the Frenet frame in four-dimensional symplectic space. We also give the characterizations of the symplectic circular helices as the third- and fourth-order differential equations involving the symplectic curvatures.
Activation of Human Dendritic Cells by Ascophyllan Purified from Ascophyllum nodosum
Authors: Zhang Wei , Kwak Minseok , Park Hae-Bin , Okimura Takasi , Oda Tatsuya , Lee Peter Chang-Whan , Jin Jun-O
Published: January 2019

In our previous study, we showed that ascophyllan purified from Ascophyllum nodosum treatment promotes mouse dendritic cell (DC) activation in vivo, further induces an antigen-specific immune response and has anticancer effects in mice. However, the effect of ascophyllan has not been studied in human immune cells, specifically in terms of activation of human monocyte-derived DCs (MDDCs) and human peripheral blood DCs (PBDCs). We found that the treatment with ascophyllan induced morphological changes in MDDCs and upregulated co-stimulatory molecules and major histocompatibility complex class I (MHC I) and MHC II expression. In addition, pro-inflammatory cytokine levels in culture medium was also dramatically increased following ascophyllan treatment of MDDCs. Moreover, ascophyllan promoted phosphorylation of ERK, p38 and JNK signaling pathways, and inhibition of p38 almost completely suppressed the ascophyllan-induced activation of MDDCs. Finally, treatment with ascophyllan induced activation of BDCA1 and BDCA3 PBDCs. Thus, these data suggest that ascophyllan could be used as an immune stimulator in humans.
Design and Synthesis of a Chitodisaccharide-Based Affinity Resin for Chitosanases Purification
Authors: Li Shangyong , Wang Linna , Chen Xuehong , Sun Mi , Han Yantao
Published: January 2019

Chitooligosaccharides (CHOS) have gained increasing attention because of their important biological activities. Enhancing the efficiency of CHOS production essentially requires screening of novel chitosanase with unique characteristics. Therefore, a rapid and efficient one-step affinity purification procedure plays important roles in screening native chitosanases. In this study, we report the design and synthesis of affinity resin for efficient purification of native chitosanases without any tags, using chitodisaccharides (CHDS) as an affinity ligand, to couple with Sepharose 6B via a spacer, cyanuric chloride. Based on the CHDS-modified affinity resin, a one-step affinity purification method was developed and optimized, and then applied to purify three typical glycoside hydrolase (GH) families: 46, 75, and 80 chitosanase. The three purified chitosanases were homogeneous with purities of greater than 95% and bioactivity recovery of more than 40%. Moreover, we also developed a rapid and efficient affinity purification procedure, in which tag-free chitosanase could be directly purified from supernatant of bacterial culture. The purified chitosanases samples using such a procedure had apparent homogeneity, with more than 90% purity and 10–50% yield. The novel purification methods established in this work can be applied to purify native chitosanases in various scales, such as laboratory and industrial scales.
The Associations between Body Mass Index of Seven- and Eight-Year-Old Children, Dietary Behaviour and Nutrition-Related Parenting Practices
Authors: Vaitkevičiūtė Justina , Petrauskienė Aušra
Published: January 2019

Background and objective: Body mass index (BMI) is one of the key indicators used to measure the growth of children. It could be affected by the children’s nutrition, which is essential for the proper development of the child. Nutrition of children could be affected by many environmental factors, for example, the socioeconomic environment of the family. The aim of this study was to identify the associations between the BMI of seven- and eight-year-old children, dietary behaviour and nutrition-related parenting practices. Materials and Methods: The study was carried out as part of the World Health Organization European Childhood Obesity Surveillance Initiative (WHO COSI). Data were collected using two instruments: objective anthropometric measurements and a questionnaire. The target participant group was 3969 Lithuanian first-formers. Factor analysis was used to summarise questions from the family form. Linear regression analysis was used to identify the associations between various factors and the BMI value of the children. The association between two groups of factors was analysed using Spearman correlation. Results: Factors of dietary behaviour like unhealthy food and proteins were significantly positively associated with BMI in children, while consumption of plant-based, dairy and confectionery items was significantly negatively associated with BMI. Factors of nutrition-related parenting practices like control of unhealthy food, food as a reward or punishment, and mealtime were significantly positively associated with BMI, while encouragement, pressure to eat, and liberal attitude were significantly negatively associated with BMI. The strongest associations were between control of unhealthy food and unhealthy food; cost of and preferences for food and plant-based food; variety of food and proteins; variety of food and plant-based food compared to other associations. Conclusions: The dietary behaviour and nutrition-related parenting practices were associated with BMI in children.
Prehospital and Emergency Care in Adult Patients with Acute Traumatic Brain Injury
Authors: Pélieu Iris , Kull Corey , Walder Bernhard
Published: January 2019

Traumatic brain injury (TBI) is a major healthcare problem and a major burden to society. The identification of a TBI can be challenging in the prehospital setting, particularly in elderly patients with unobserved falls. Errors in triage on scene cannot be ruled out based on limited clinical diagnostics. Potential new mobile diagnostics may decrease these errors. Prehospital care includes decision-making in clinical pathways, means of transport, and the degree of prehospital treatment. Emergency care at hospital admission includes the definitive diagnosis of TBI with, or without extracranial lesions, and triage to the appropriate receiving structure for definitive care. Early risk factors for an unfavorable outcome includes the severity of TBI, pupil reaction and age. These three variables are core variables, included in most predictive models for TBI, to predict short-term mortality. Additional early risk factors of mortality after severe TBI are hypotension and hypothermia. The extent and duration of these two risk factors may be decreased with optimal prehospital and emergency care. Potential new avenues of treatment are the early use of drugs with the capacity to decrease bleeding, and brain edema after TBI. There are still many uncertainties in prehospital and emergency care for TBI patients related to the complexity of TBI patterns.
Influence of Al on Evolution of the Inclusions in Ti-Bearing Steel with Ca Treatment
Authors: Li Yandong , Zhang Tongsheng , Duan Huamei
Published: January 2019

Experimental simulations of steelmaking with different amounts of aluminum were achieved in the tube furnace at 1873 K and field scanning electron microscopy and energy dispersive X-ray spectroscopy (FE-SEM and EDX) were employed to explore the characteristics of the inclusions in Ti-bearing steel during the calcium treatment process. It was found that morphologies, chemical compositions, and the size distribution of the inclusions were obviously different before and after calcium treatment. The calcium addition need be carefully considered regarding the mass fraction of aluminum with the purpose of modifying the solid inclusions to liquid phases. The thermodynamic analysis of inclusion formation in the Al–Ti–Ca–O system at 1873 K was conducted, as well as transformation behaviors of inclusions including all types of solid inclusions and liquid phases during solidification. The thermodynamic equilibrium calculations are in good agreement with experimental data, which can be used to estimate inclusion formation in Ti-bearing steel.
Repair and Reinforcement of Historic Timber Structures with Stainless Steel—A Review
Authors: Corradi Marco , Osofero Adelaja Israel , Borri Antonio
Published: January 2019

Recent trends in the use of stainless steel profiles for repair and reinforcement of historic timber structures, after degradation due to biotic and non-biotic attacks, are discussed in this paper. These structural challenges can vary from inadequate load carrying capacity to complexities involved with choice of repair materials and techniques. Given the recurring requirements of conservation authorities in terms of reversibility of interventions and compatibility between historic and new materials, an increase in the use of non-invasive reinforcement materials and reversible techniques was observed. Subsequently, engineers and researchers have increasingly employed stainless steel alloys in retrofitting historic timber structures. This paper therefore presents the state of the art in the use of stainless steel profiles in retrofitting timber structural elements within historic structures. It includes a review of the development of the retrofitting methods and existing experimental studies on the mechanical behavior of timber structures reinforced with stainless steel. Finally, it presents a number of case studies and draws conclusions on current trends and practices based on reported studies.
Effects of Yb Addition on the Microstructure and Mechanical Properties of As-Cast ADC12 Alloy
Authors: Xiong Junjie , Yan Hong , Zhong Songgen , Bi Minzhu
Published: January 2019

The effects of addition of different amounts of rare earth ytterbium (Yb) on the microstructure and mechanical properties of the casting ADC12 alloy were investigated by mechanical properties testing and microstructure observation. The results indicate that Yb modification had a big influence on the microstructure and properties of the as-cast alloy. The optimum level of Yb content was 0.8 wt %. The coarse dendritic primary α-Al phases were fully refined, leading to the decreasing of the secondary dendrite arm spacing. The morphology of eutectic silicon phases changed from acicular into short rod-like and even granular. There was a structural transformation of β-Fe phases from massive to small rod-shaped morphology. Additionally, the tensile strength, elongation, and microhardness were 267.9 MPa, 4.2%, and 107.3 HV, respectively, increases of 55.4, 121.1, and 41.4%, respectively, compared with the matrix alloy. Fractographic examinations reveal that mainly ductile fracture for Yb addition of 0.8 wt %. The fracture appearances matched the tendency of the tensile properties. Furthermore, the addition of Yb can generate a rare earth phase consisting of the three elements of Al, Si, Yb, with some small iron-rich phases attached around the rare earth phase.
Marine Polysaccharide-Collagen Coatings on Ti6Al4V Alloy Formed by Self-Assembly
Authors: Norris Karl , Mishukova Oksana I. , Zykwinska Agata , Colliec-Jouault Sylvia , Sinquin Corinne , Koptioug Andrei , Cuenot Stéphane , Kerns Jemma G. , Surmeneva Maria A. , Surmenev Roman A. , Douglas Timothy E.L.
Published: January 2019

Polysaccharides of marine origin are gaining interest as biomaterial components. Bacteria derived from deep-sea hydrothermal vents can produce sulfated exopolysaccharides (EPS), which can influence cell behavior. The use of such polysaccharides as components of organic, collagen fibril-based coatings on biomaterial surfaces remains unexplored. In this study, collagen fibril coatings enriched with HE800 and GY785 EPS derivatives were deposited on titanium alloy (Ti6Al4V) scaffolds produced by rapid prototyping and subjected to physicochemical and cell biological characterization. Coatings were formed by a self-assembly process whereby polysaccharides were added to acidic collagen molecule solution, followed by neutralization to induced self-assembly of collagen fibrils. Fibril formation resulted in collagen hydrogel formation. Hydrogels formed directly on Ti6Al4V surfaces, and fibrils adsorbed onto the surface. Scanning electron microscopy (SEM) analysis of collagen fibril coatings revealed association of polysaccharides with fibrils. Cell biological characterization revealed good cell adhesion and growth on bare Ti6Al4V surfaces, as well as coatings of collagen fibrils only and collagen fibrils enhanced with HE800 and GY785 EPS derivatives. Hence, the use of both EPS derivatives as coating components is feasible. Further work should focus on cell differentiation.
Vibration Induced Transport of Enclosed Droplets
Authors: Holmes Hal , Böhringer Karl
Published: January 2019

The droplet response to vibrations has been well characterized on open substrates, but microfluidic applications for droplets on open systems are limited by rapid evaporation rates and prone to environmental contamination. However, the response of enclosed droplets to vibration is less understood. Here, we investigate the effects of a dual-plate enclosure on droplet transport for the anisotropic ratchet conveyor system. This system uses an asymmetric pattern of hydrophilic rungs to transport droplets with an applied vibration. Through this work, we discovered that the addition of a substrate on top of the droplet, held in place with a 3D printed fixture, extends the functional frequency range for droplet transport and normalizes the device performance for droplets of different volumes. Furthermore, we found that the edge movements are anti-phasic between top and bottom substrates, providing a velocity profile that is correlated to vibration frequency, unlike the resonance-dependent profiles observed on open systems. These results expand the capabilities of this system, providing avenues for new applications and innovation, but also new insights for droplet mechanics in response to applied vibration.
A Miniaturized Circularly-Polarized Antenna for In-Body Wireless Communications
Authors: Fan Yi , Liu Xiongying , Li Jiming , Chang Tianhai
Published: January 2019

A novel miniaturized single-fed circularly-polarized (CP) microstrip patch antenna operating in the Industrial, Scientific, Medical (ISM) band of 2.40–2.48 GHz, is comprehensively proposed for implantable wireless communications. By employing reactive loading in the arrow-shaped slotted patch to form slow wave effect and embedding V-shaped slots into patch to lengthen the current path, the proposed implantable antenna is minimized with the overall dimensions of 9.2 mm × 9.2 mm × 1.27 mm. The radiation patterns of the proposed antenna illustrate the performance of left-handed circular polarization. The simulated results show that an impedance bandwidth of 7.2% (2.39–2.57 GHz) and an axial ratio bandwidth of 3.7% (2.39–2.48 GHz) at the ISM band are achieved, respectively. Ex vivo measured results are in good agreement with the corresponding simulated ones.
Unique PGE–Cu–Ni Noril’sk Deposits, Siberian Trap Province: Magmatic and Tectonic Factors in Their Origin
Authors: Krivolutskaya Nadezhda A. , Latyshev Anton V. , Dolgal Alexander S. , Gongalsky Bronislav I. , Makarieva Elena M. , Makariev Alexander A. , Svirskaya Natalia M. , Bychkova Yana V. , Yakushev Anton I. , Asavin Alexey M.
Published: January 2019

The unique and very large PGE–Cu–Ni Noril’sk deposits are located within the Siberian trap province, posing a number of questions about the relationship between the ore-forming process and the magmatism that produced the traps. A successful answer to these questions could greatly increase the possibility of discovering new deposits in flood basalt provinces elsewhere. In this contribution, we present new data on volcanic stratigraphy and geochemistry of the magmatic rocks in the key regions of the Siberian trap province (Noril’sk, Taimyr, Maymecha-Kotuy, Kulyumber, Lower Tunguska and Angara) and analyze the structure of the north part of the province. The magmatic rocks of the Arctic zone are characterized by variable MgO (3.6–37.2 wt %) and TiO2 (0.8–3.9 wt %) contents, Gd/Yb (1.4–6.3) and La/Sm (2.0–10.4) ratios, and a large range of isotopic compositions. The intrusions in the center of the Tunguska syneclise and Angara syncline have much less variable compositions and correspond to a “typical trap” with MgO of 5.6–7.2 wt %, TiO2 of 1.0–1.6 wt %, Gd/Yb ratio of 1.4–1.6 and La/Sm ratio of 2.0–3.5. This compositional diversity of magmas in the Arctic zone is consistent with their emplacement within the paleo-rift zones. Ore-bearing intrusions (the Noril’sk 1, Talnakh, Kharaelakh) are deep-situated in the Igarka-Noril’sk rift zone, which has three branches, namely the Bolsheavamsky, Dyupkunsky, and Lower Tunguska, that are prospected for discovering new deposits. One possible explanation for the specific position of the PGE–Cu–Ni deposits is accumulation of sulfides in these long-lived zones from the Neoproterozoic to the Mesozoic era during magmatic and metamorphic processes. Thus, trap magmatism, itself, does not produce large deposits, but mobilizes earlier formed sulfide segregations in addition carrying metals in the original magmas. These deposits are the results of several successive magmatic events, in which emplacement of the traps was the final event.
Rare Earth Hydroxide as a Precursor for Controlled Fabrication of Uniform β-NaYF4 Nanoparticles: A Novel, Low Cost, and Facile Method
Authors: Xu Lili , Wang Man , Chen Qing , Yang Jiajia , Zheng Wubin , Lv Guanglei , Quan Zewei , Li Chunxia
Published: January 2019

In recent years, rare earth doped upconversion nanocrystals have been widely used in different fields owing to their unique merits. Although rare earth chlorides and trifluoroacetates are commonly used precursors for the synthesis of nanocrystals, they have certain disadvantages. For example, rare earth chlorides are expensive and rare earth trifluoroacetates produce toxic gases during the reaction. To overcome these drawbacks, we use the less expensive rare earth hydroxide as a precursor to synthesize β-NaYF4 nanoparticles with multiform shapes and sizes. Small-sized nanocrystals (15 nm) can be obtained by precisely controlling the synthesis conditions. Compared with the previous methods, the current method is more facile and has lower cost. In addition, the defects of the nanocrystal surface are reduced through constructing core–shell structures, resulting in enhanced upconversion luminescence intensity.
Development and Validation of a LC–MS/MS-Based Assay for Quantification of Free and Total Omega 3 and 6 Fatty Acids from Human Plasma
Authors: Serafim Vlad , Tiugan Diana-Andreea , Andreescu Nicoleta , Mihailescu Alexandra , Paul Corina , Velea Iulian , Puiu Maria , Niculescu Mihai Dinu
Published: January 2019

Few high-performance liquid chromatography–tandem mass spectrometry (LC-MS/MS) methods have been developed for the full quantitation of fatty acids from human plasma without derivatization. Therefore, we propose a method that requires fewer sample preparation steps, which can be used for the quantitation of several polyunsaturated fatty acids in human plasma. The method offers rapid, accurate, sensitive, and simultaneous quantification of omega 3 (α-linolenic, eicosapentaenoic, and docosahexaenoic acids) and omega 6 fatty acids (arachidonic and linoleic acids) using high-performance LC-MS/MS. The selected fatty acids were analysed in lipid extracts from both free and total forms. Chromatographic separation was achieved using a reversed phase C18 column with isocratic flow using ammonium acetate for improving negative electrospray ionization (ESI) response. Mass detection was performed in multiple reaction monitoring (MRM) mode, and deuterated internal standards were used for each target compound. The limits of quantification were situated in the low nanomolar range, excepting linoleic acid, for which the limit was in the high nanomolar range. The method was validated according to the U.S. Department of Health and Human Services guidelines, and offers a fast, sensitive, and reliable quantification of selected omega 3 and 6 fatty acids in human plasma.
Solution Combustion Synthesis of Cr2O3 Nanoparticles and the Catalytic Performance for Dehydrofluorination of 1,1,1,3,3-Pentafluoropropane to 1,3,3,3-Tetrafluoropropene
Authors: Wang Haili , Han Wenfeng , Li Xiliang , Liu Bing , Tang Haodong , Li Ying
Published: January 2019

Cr2O3 nanoparticles were prepared by solution combustion synthesis (SCS) with chromium nitrate as the precursor and glycine as the fuel. Commercial Cr2O3 and Cr2O3 prepared by a precipitation method were also included for comparison. The morphology, structure, acidity and particle size of fresh and spent Cr2O3 catalysts were investigated by techniques such as XRD, SEM, TEM, BET and NH3-TPD. In addition, catalytic performance was evaluated for the dehydrofluorination of 1,1,1,3,3-pentafluoropropane (CF3CH2CHF2, HFC-245fa) to 1,3,3,3-tetra-fluoropropene (CF3CH=CHF, HFO-1234ze). The catalytic reaction rate of Cr2O3 prepared by SCS method is as high as 6 mmol/h/g, which is about 1.5 times and 2 times higher than that of precipitated Cr2O3 and commercial Cr2O3, respectively. The selectivity to HFO-1234ze for all the catalysts maintains at about 80%. Compared with commercial and precipitated Cr2O3, Cr2O3-SCS prepared by SCS possesses higher specific surface area and acid amount. Furthermore, significant change in the crystal size of Cr2O3 prepared by SCS after reaction was not detected, indicating high resistance to sintering.
Effects of Betaine on LPS-Stimulated Activation of Microglial M1/M2 Phenotypes by Suppressing TLR4/NF-κB Pathways in N9 Cells
Authors: Shi Hui , Wang Xiao-Long , Quan Hong-Feng , Yan Lin , Pei Xiu-Ying , Wang Rui , Peng Xiao-Dong
Published: January 2019

Microglia mediate multiple facets of neuroinflammation. They can be phenotypically divided into a classical phenotype (pro-inflammatory, M1) or an alternative phenotype (anti-inflammatory, M2) with different physiological characteristics and biological functions in the inflammatory process. Betaine has been shown to exert anti-inflammatory effects. In this study, we aimed to verify the anti-inflammatory effects of betaine and elucidate its possible molecular mechanisms of action in vitro. Lipopolysaccharide (LPS)-activated microglial cells were used as an inflammatory model to study the anti-inflammatory efficacy of betaine and explore its mechanism of regulating microglial polarisation by investigating the morphological changes and associated inflammatory changes. Cytokine and inflammatory mediator expression was also measured by ELISA, flow cytometry, immunofluorescence, and western blot analysis. Toll-like receptor (TLR)-myeloid differentiation factor 88 (Myd88)-nuclear factor-kappa B (NF-κB) p65, p-NF-κB p65, IκB, p-IκB, IκB kinase (IKK), and p-IKK expression was determined by western blot analysis. Betaine significantly mitigated the production of pro-inflammatory cytokines and increased the release of anti-inflammatory cytokines. It promoted the conversion of the microglia from M1 to M2 phenotype by decreasing the expression of inducible nitric oxide synthase and CD16/32 and by increasing that of CD206 and arginase-1. Betaine treatment inhibited the TLR4/NF-κB pathways by attenuating the expression of TLR4-Myd88 and blocking the phosphorylation of IκB and IKK. In conclusion, betaine could significantly alleviate LPS-induced inflammation by regulating the polarisation of microglial phenotype; thus, it might be an effective therapeutic agent for neurological disorders.
Functionalization of the Chalcone Scaffold for the Discovery of Novel Lead Compounds Targeting Fungal Infections
Authors: Bonvicini Francesca , Gentilomi Giovanna A. , Bressan Francesca , Gobbi Silvia , Rampa Angela , Bisi Alessandra , Belluti Federica
Published: January 2019

The occurrence of invasive fungal infections represents a substantial threat to human health that is particularly serious in immunocompromised patients. The limited number of antifungal agents, devoid of unwanted toxic effects, has resulted in an increased demand for new drugs. Herein, the chalcone framework was functionalized to develop new antifungal agents able to interfere with cell growth and with the infection process. Thus, a small library of chalcone-based analogues was evaluated in vitro against C. albicans ATCC 10231 and a number of compounds strongly inhibited yeast growth at non-cytotoxic concentrations. Among these, 5 and 7 interfered with the expression of two key virulence factors in C. albicans pathogenesis, namely, hyphae and biofilm formation, while 28 emerged as a potent and broad spectrum antifungal agent, enabling the inhibition of the tested Candida spp. and non-Candida species. Indeed, these compounds combine two modes of action by selectively interfering with growth and, as an added value, weakening microbial virulence. Overall, these compounds could be regarded as promising antifungal candidates worthy of deeper investigation. They also provide a chemical platform through which to perform an optimization process, addressed at improving potency and correcting liabilities.
Design and Synthesis of a Fluorescent Probe with a Large Stokes Shift for Detecting Thiophenols and Its Application in Water Samples and Living Cells
Authors: Liu Hua , Guo Chuanlong , Guo Shuju , Wang Lijun , Shi Dayong
Published: January 2019

A turn-on florescent probe (probe-KCP) was developed for highly selective detection of thiophenols based on a donor-excited photo-induced electron transfer mechanism. Herein, the synthesis of the probe, a chalcone derivative, through a simple straightforward combination of a carbazole-chalcone fluorophore with a 2,4-dinitrophenyl functional group. In a kinetic study of the probe-KCP for thiophenols, the probe displayed a short response time (~30 min) and significant fluorescence enhancement. In selection and competition experiments, the probe-KCP exhibited excellent selectivity for thiophenols over glutathione (GSH), cysteine (Cys), sodium hydrosulfide (NaSH), and ethanethiol (C2H5SH) in addition to common anions and metal ions. Using the designed probe, we successfully monitored and quantified thiophenols, which are highly toxic. This turn-on fluorescence probe features a remarkably large Stokes shift (130 nm) and a short response time (30 min), and it is highly selective and sensitive (~160-fold) in the detection of thiophenols, with marked fluorescence in the presence of thiophenols. probe-KCP responds to thiophenols with a good range of linearity (0–15 μM) and a detection limit of 28 nM (R2 = 0.9946) over other tested species mentioned including aliphatic thiols, thiophenol analogues, common anions, and metal ions. The potential applications of this carbazole-chalcone fluorescent probe was successfully used to determine of thiophenols in real water samples and living cells with good performance and low cytotoxicity. Therefore, this probe has great potential application in environment and biological samples.
Linear and Nonlinear Intersubband Optical Properties of Direct Band Gap GeSn Quantum Dots
Authors: Baira Mourad , Salem Bassem , Madhar Niyaz Ahmad , Ilahi Bouraoui
Published: January 2019

Intersubband optical transitions, refractive index changes, and absorption coefficients are numerically driven for direct bandgap strained GeSn/Ge quantum dots. The linear, third-order nonlinear and total, absorption coefficients and refractive index changes are evaluated over useful dot sizes’ range ensuring p-like Γ-electron energy state to be lower than s-like L-electron energy state. The results show strong dependence of the total absorption coefficient and refractive index changes on the quantum dot sizes. The third order nonlinear contribution is found to be sensitive to the incident light intensity affecting both total absorption coefficient and refractive index changes, especially for larger dot sizes.
Dietary Intake Reporting Accuracy of the Bridge2U Mobile Application Food Log Compared to Control Meal and Dietary Recall Methods
Authors: Lemacks Jennifer L. , Adams Kristen , Lovetere Ashley
Published: January 2019

Mobile technology introduces opportunity for new methods of dietary assessment. The purpose of this study was to compare the reporting accuracy of a mobile food log application and 24 h recall method to a controlled meal among a convenience sample of adults (18 years of age or older). Participants were recruited from a community/university convenience sample. Participants consumed a pre-portioned control meal, completed mobile food log entry (mfood log), and participated in a dietary recall administered by a registered dietitian (24R). Height, weight, and application use survey data were collected. Sign test, Pearson’s correlation, and descriptive analyses were conducted to examine differences in total and macronutrient energy intake and describe survey responses. Bland Altman plots were examined for agreement between energy intake from control and 24R and mfood log. The 14 included in the analyses were 78.6% female, 85.7% overweight/obese, and 64.3% African American. Mean total energy, protein, and fat intakes reported via the mfood log were significantly (p < 0.05) lower compared to the control, by 268.31kcals, 20.37 g, and 19.51 g, respectively. Only 24R mean fat intake was significantly (p < 0.01) lower than the control, by 6.43 g. Significant associations (r = 0.57–0.60, p < 0.05) were observed between control and mfood log mean energy, carbohydrate, and protein intakes, as well as between control and 24R mean energy (r = 0.64, p = 0.01) and carbohydrate (r = 0.81, p < 0.001) intakes. Bland Altman plots showed wide limits of agreement, which were not statistically significant but may have practical limitations for individual dietary assessment. Responses indicated the ease of and likelihood of daily mfood log use. This study demonstrates that the Bridge2U mfood log is valid for the assessment of group level data, but data may vary too widely for individual assessment. Further investigation is warranted for nutrition intervention research.
Zn-DTSM, A Zinc Ionophore with Therapeutic Potential for Acrodermatitis Enteropathica?
Authors: Bray Lisa , Volitakis Irene , Ayton Scott , Bush Ashley I. , Adlard Paul A.
Published: January 2019

Acrodermatitis enteropathica (AE) is a rare disease characterised by a failure in intestinal zinc absorption, which results in a host of symptoms that can ultimately lead to death if left untreated. Current clinical treatment involves life-long high-dose zinc supplements, which can introduce complications for overall nutrient balance in the body. Previous studies have therefore explored the pharmacological treatment of AE utilising metal ionophore/transport compounds in an animal model of the disease (conditional knockout (KO) of the zinc transporter, Zip4), with the perspective of finding an alternative to zinc supplementation. In this study we have assessed the utility of a different class of zinc ionophore compound (zinc diethyl bis(N4-methylthiosemicarbazone), Zn-DTSM; Collaborative Medicinal Development, Sausalito, CA, USA) to the one we have previously described (clioquinol), to determine whether it is effective at preventing the stereotypical weight loss present in the animal model of disease. We first utilised an in vitro assay to assess the ionophore capacity of the compound, and then assessed the effect of the compound in three in vivo animal studies (in 1.5-month-old mice at 30 mg/kg/day, and in 5-month old mice at 3 mg/kg/day and 30 mg/kg/day). Our data demonstrate that Zn-DTSM has a pronounced effect on preventing weight loss when administered daily at 30 mg/kg/day; this was apparent in the absence of any added exogenous zinc. This compound had little overall effect on zinc content in various tissues that were assessed, although further characterisation is required to more fully explore the cellular changes underlying the physiological benefit of this compound. These data suggest that Zn-DTSM, or similar compounds, should be further explored as potential therapeutic options for the long-term treatment of AE.
Magnetic Mixed Micelles Composed of a Non-Ionic Surfactant and Nitroxide Radicals Containing a d-Glucosamine Unit: Preparation, Stability, and Biomedical Application
Authors: Nagura Kota , Takemoto Yusa , Yoshino Fumi , Bogdanov Alexey , Chumakova Natalia , Vorobiev Andrey Kh. , Imai Hirohiko , Matsuda Tetsuya , Shimono Satoshi , Kato Tatsuhisa , Komatsu Naoki , Tamura Rui
Published: January 2019

Metal-free magnetic mixed micelles (mean diameter: < 20 nm) were prepared by mixing the biocompatible non-ionic surfactant Tween 80 and the non-toxic, hydrophobic pyrrolidine-N-oxyl radicals bearing a d-glucosamine unit in pH 7.4 phosphate-buffered saline (PBS). The time-course stability and in vitro magnetic resonance imaging (MRI) contrast ability of the mixed micelles was found to depend on the length of the alkyl chain in the nitroxide radicals. It was also confirmed that the mixed micelles exhibited no toxicity in vivo and in vitro and high stability in the presence of a large excess of ascorbic acid. The in vivo MRI experiment revealed that one of these mixed micelles showed much higher contrast enhancement in the proton longitudinal relaxation time (T1) weighted images than other magnetic mixed micelles that we have reported previously. Thus, the magnetic mixed micelles presented here are expected to serve as a promising contrast agent for theranostic nanomedicines, such as MRI-visible targeted drug delivery carriers.
Morphology Evolution and Rheological Behaviors of PP/SR Thermoplastic Vulcanizate
Authors: Wu Qiang , Fang Jiafeng , Zheng Minghuan , Luo Yan , Wang Xu , Xu Lixin , Zhang Chunhui
Published: January 2019

The thermoplastic vulcanizates (TPVs) of polypropylene (PP)/silicone rubber (SR) were prepared by dynamic vulcanization (DV) technology. The mixing torque, morphology, viscoelasticity, and creep response of PP/SR TPVs were investigated by torque rheometer, scanning electron microscope (SEM), transmission electron microscope (TEM), rotational rheometer, and dynamic mechanical analysis (DMA). A mixing-torque study showed that torque change and dynamic-vulcanization time increased with SR content increasing in the DV process, but DV rate was independent of SR content. TEM images indicated that the phase inversion of PP/SR-60 TPV from bicontinuous to a sea–island structure took place in the DV process, and a hot press would break the rubber aggregates and shrink a large SR phase. Dynamic-strain measurement demonstrated that PP/SR TPVs exhibit a distinct “Payne effect”, which can be attributed to the destruction and reconstruction of SR physical networks. Complex viscosity indicated that SR content did not affect the processability of PP/SR TPVs at high shear rates. Furthermore, the creep deformation and recovery of PP/SR TPVs at solid and melt states were studied, respectively.
Use of Grafted Voltage Stabilizer to Enhance Dielectric Strength of Cross-Linked Polyethylene
Authors: Dong Wei , Wang Xuan , Tian Bo , Liu Yuguang , Jiang Zaixing , Li Zhigang , Zhou Wei
Published: January 2019

Aromatic voltage stabilizers can improve the dielectric properties of cross-linked polyethylene (XLPE); however, their poor compatibility with XLPE hinders their practical application. Improving the compatibility of aromatic voltage stabilizers with XLPE has, therefore, become a new research goal. Herein 1-(4-vinyloxy)phenylethenone (VPE) was prepared and characterized. It can be grafted onto polyethylene molecules during the cross-linking processes to promote stability of the aromatic voltage stabilizers in XLPE. Fourier transform infrared spectroscopy confirmed that VPE was successfully grafted onto XLPE, and effectively inhibited thermal migration. Thermogravimetric analysis showed that the grafted VPE/XLPE composite exhibits a better thermal stability than a VPE/PE blend composite. Evaluation of the electrical properties showed that the breakdown strength and electrical tree initiation voltage of the VPE/XLPE composite were increased by 15.5% and 39.6%, respectively, when compared to those of bare XLPE. After thermal aging, the breakdown strength and electrical tree initiation voltage of the VPE/XLPE composite were increased by 9.4% and 25.8%, respectively, in comparison to those of bare XLPE, which indicates that the grafted voltage stabilizer can effectively inhibit its migration and enhance the stability of the composite material.
Color Tuning by Oxide Addition in PEDOT:PSS-Based Electrochromic Devices
Authors: Levasseur Delphin , Mjejri Issam , Rolland Thomas , Rougier Aline
Published: January 2019

Poly(3,4-ethylenedi-oxythiophene) (PEDOT) derivatives conducting polymers are known for their great electrochromic (EC) properties offering a reversible blue switch under an applied voltage. Characterizations of symmetrical EC devices, built on combinations of PEDOT thin films, deposited with a bar coater from commercial inks, and separated by a lithium-based ionic membrane, show highest performance for 800 nm thickness. Tuning of the color is further achieved by mixing the PEDOT film with oxides. Taking, in particular, the example of optically inactive iron oxide Fe2O3, a dark blue to reddish switch, of which intensity depends on the oxide content, is reported. Careful evaluation of the chromaticity parameters L*, a*, and b*, with oxidizing/reducing potentials, evidences a possible monitoring of the bluish tint.
Functional Porous Carboxymethyl Cellulose/Cellulose Acetate Composite Microspheres: Preparation, Characterization, and Application in the Effective Removal of HCN from Cigarette Smoke
Authors: Sun Peijian , Yang Song , Sun Xuehui , Wang Yipeng , Pan Lining , Wang Hongbo , Wang Xiaoyu , Guo Jizhao , Nie Cong
Published: January 2019

To selectively reduce the yield of hydrogen cyanide (HCN) in the cigarette smoke, functional porous carboxymethyl cellulose/cellulose acetate (CMC/CA) composite microspheres were prepared via the double emulsion-solvent evaporation method. Cupric ions, which have a high complexing ability toward HCN, were introduced to the CMC/CA composite microspheres during the fabrication process via an in situ ion cross-link method. The microspheres were characterized using nitrogen adsorption, mercury intrusion porosimetry, and scanning electron microscopy (SEM). The microspheres have a predominantly macroporous structure indicating weak physisorption properties, but sufficient functional cupric ion groups to selectively adsorb HCN. With these CMC/CA microspheres as filter additives, the smoke yield of HCN could be reduced up to 50%, indicating the great potential of these microspheres as absorbents for removing HCN from cigarette smoke.
Photocatalytic Dye and Cr(VI) Degradation Using a Metal-Free Polymeric g-C3N4 Synthesized from Solvent-Treated Urea
Authors: Hu Chechia , Chu Yi-Ching , Lin Yan-Ru , Yang Hung-Chun , Wang Ke-Hsuan
Published: January 2019

The development of visible-light-driven polymeric g-C3N4 is in response to an emerging demand for the photocatalytic dye degradation and reduction of hexavalent chromium ions. We report the synthesis of g-C3N4 from urea treated with various solvents such as methanol, ethanol, and ethylene glycol. The samples were characterized and the Williamson–Hall method was applied to investigate the lattice strain of the samples. The activity of the samples was evaluated by observing the degradation of methyl orange and K2Cr2O7 solution under light irradiation. Photocatalytic reaction kinetics were determined as pseudo-first-order and zero-order for the degradation of methyl orange and reduction of hexavalent chromium, respectively. Due to the inhibited charge separation resulting from the small lattice strain, reduced crystal imperfection, and sheet-like structure, g-C3N4 obtained from ethanol-treated urea exhibited the highest activity among the evaluated samples.