bluuebunny/crossref_metadata_2025 huggingface dataset:
Economic Burden of Hospitalization Due to Injuries in North India: A Cohort Study
Authors: Prinja Shankar , Jagnoor Jagnoor , Chauhan Akashdeep , Aggarwal Sameer , Nguyen Ha , Ivers Rebecca
Published: July 2016

There is little documentation of the potential catastrophic effects of injuries on families due to out of pocket (OOP) expenditure for medical care. Patients who were admitted for at least one night in a tertiary care hospital of Chandigarh city due to injury were recruited and were followed-up at 1, 2 and 12 months after discharge to collect information on OOP expenditure. Out of the total 227 patients, 60% (137/227) had sustained road traffic injuries (RTI). The average OOP expenditure per hospitalisation and up to 12 months post discharge was USD 388 (95% CI: 332–441) and USD 1046 (95% CI: 871–1221) respectively. Mean OOP expenditure for RTI and non-RTI cases during hospitalisation was USD 400 (95% CI: 344–456) and USD 369 (95% CI: 313–425) respectively. The prevalence of catastrophic expenditure was 30%, and was significantly higher among those belonging to the lowest income quartile (OR-26.50, 95% CI: 6.70–105.07, p-value: <0.01) and with an inpatient stay greater than 7 days (OR-10.60, 95% CI: 4.21–26.64, p-value: <0.01). High OOP expenditure for treatment of injury puts a significant economic burden on families. Measures aimed at increasing public health spending for prevention of injury and providing financial risk protection are urgently required in India.
Determination of Free-Form and Peptide Bound Pyrraline in the Commercial Drinks Enriched with Different Protein Hydrolysates
Authors: Liang Zhili , Li Lin , Qi Haiping , Zhang Xia , Xu Zhenbo , Li Bing
Published: July 2016

Pyrraline, a causative factor for the recent epidemics of diabetes and cardiovascular disease, is also employed as an indicator to evaluate heat damage and formation of advanced glycation end-products (AGEs) in foods. Peptide-enriched drinks (PEDs) are broadly consumed worldwide due to rapid rate of absorption and perceived health effects. It can be hypothesized that PED is an important source of pyrraline, especially peptide bound pyrraline (Pep-Pyr). In this study we determined free-form pyrraline (Free-Pyr) and Pep-Pyr in drinks enriched with whey protein hydrolysate (WPH), soy protein hydrolysate (SPH) and collagen protein hydrolysate (CPH). A detection method was developed using ultrahigh-performance liquid chromatography with UV-visible detector coupled with tandem mass spectrometry after solid-phase extraction (SPE). The SPE led to excellent recovery rates ranging between 93.2% and 98.5% and a high reproducibility with relative standard deviations (RSD) of <5%. The limits of detection and quantification obtained were 30.4 and 70.3 ng/mL, respectively. Pep-Pyr was identified as the most abundant form (above 96 percent) of total pyrraline, whereas Free-Pyr was present in a small proportion (less than four percent) of total pyrraline. The results indicate that PED is an important extrinsic source of pyrraline, especially Pep-Pyr. As compared with CPH- and SPH-enriched drinks, WPH-enriched drinks contained high content of Pep-Pyr. The Pep-Pyr content is associated with the distribution of peptide lengths and the amino acid compositions of protein in PEDs.
Effects of Carbonization Temperature and Component Ratio on Electromagnetic Interference Shielding Effectiveness of Woodceramics
Authors: Tao Yubo , Li Peng , Shi Sheldon
Published: July 2016

Woodceramics were fabricated in a vacuum through carbonization of wood powder impregnated with phenol formaldehyde (PF) resin. The effects of carbonization temperature and mass ratio of wood/resin on electromagnetic interference (EMI) shielding effectiveness (SE) and morphology of woodceramics were explored. The PF resin made wood cell walls have the characteristics of glassy carbon. Wood axial tracheid and ray cells were filled with more glassy carbon by increasing addition of PF resin. Moreover, the increase of carbonization temperature was beneficial to improving SE. Woodceramics (mass ratio 1:1) obtained at 1000 °C presented a medium SE level between 30 MHz and 1.5 GHz.
Self-Assembly and Drug Release Capacities of Organogels via Some Amide Compounds with Aromatic Substituent Headgroups
Authors: Zhang Lexin , Jiao Tifeng , Ma Kai , Xing Ruirui , Liu Yamei , Xiao Yong , Zhou Jingxin , Zhang Qingrui , Peng Qiuming
Published: July 2016

In this work, some amide compounds with different aromatic substituent headgroups were synthesized and their gelation self-assembly behaviors in 22 solvents were characterized as new gelators. The obtained results indicated that the size of aromatic substituent headgroups in molecular skeletons in gelators showed crucial effect in the gel formation and self-assembly behavior of all compounds in the solvents used. Larger aromatic headgroups in molecular structures in the synthesized gelator molecules are helpful to form various gel nanostructures. Morphological investigations showed that the gelator molecules can self-assembly and stack into various organized aggregates with solvent change, such as wrinkle, belt, rod, and lamella-like structures. Spectral characterizations suggested that there existed various weak interactions including π-π stacking, hydrogen bonding, and hydrophobic forces due to aromatic substituent headgroups and alkyl substituent chains in molecular structures. In addition, the drug release capacities experiments demonstrated that the drug release rate in present obtained gels can be tuned by adjusting the concentrations of dye. The present work would open up enormous insight to design and investigate new kind of soft materials with designed molecular structures and tunable drug release performance.
Microfluidic Autologous Serum Eye-Drops Preparation as a Potential Dry Eye Treatment
Authors: Yasui Takao , Morikawa Jumpei , Kaji Noritada , Tokeshi Manabu , Tsubota Kazuo , Baba Yoshinobu
Published: July 2016

Dry eye is a problem in tearing quality and/or quantity and it afflicts millions of persons worldwide. An autologous serum eye-drop is a good candidate for dry eye treatment; however, the eye-drop preparation procedures take a long time and are relatively troublesome. Here we use spiral microchannels to demonstrate a strategy for the preparation of autologous serum eye-drops, which provide benefits for all dry eye patients; 100% and 90% removal efficiencies are achieved for 10 μm microbeads and whole human blood cells, respectively. Since our strategy allows researchers to integrate other functional microchannels into one device, such a microfluidic device will be able to offer a new one-step preparation system for autologous serum eye-drops.
Carlina acaulis Exhibits Antioxidant Activity and Counteracts Aβ Toxicity in Caenorhabditis elegans
Authors: Link Pille , Roth Kevin , Sporer Frank , Wink Michael
Published: July 2016

Carlina acaulis is a medicinal plant that has shown antioxidant activity in in vitro studies, but to date no corresponding in vivo data is available. Therefore, in the present study the antioxidant activity and its impact in counteracting Aβ toxicity were studied in the Caenorhabditis elegans model. A dichloromethane extract of the roots of C. acaulis was prepared and characterised via gas-liquid-chromatography/mass-spectrometry (GLC-MS). The in vitro antioxidant activity was confirmed via 2,2-diphenyl-1-picrylhydracyl assay. The extract was further separated by thin layer chromatography into two fractions, one of which was a fraction of the dichloromethane extract of C. acaulis containing mostly Carlina oxide (CarOx). Different strains of C. elegans were employed to study the expression of hsp-16.2p::GFP as a marker for oxidative stress, delocalisation of the transcription factor DAF-16 as a possible mechanism of antioxidant activity, the effect of the drug under lethal oxidative stress, and the effect against beta-amyloid (Aβ) toxicity in a paralysis assay. The C. acaulis extract and CarOx showed high antioxidant activity (stress reduction by 47% and 64%, respectively) in C. elegans and could activate the transcription factor DAF-16 which directs the expression of anti-stress genes. In paralysis assay, only the total extract was significantly active, delaying paralysis by 1.6 h. In conclusion, in vivo antioxidant activity was shown for C. acaulis for the first time in the C. elegans model. The active antioxidant compound is Carlina oxide. This activity, however, is not sufficient to counteract Aβ toxicity. Other mechanisms and possibly other active compounds are involved in this effect.
Design and Stereochemical Research (DFT, ECD and Crystal Structure) of Novel Bedaquiline Analogs as Potent Antituberculosis Agents
Authors: Geng Yiding , Li Linwei , Wu Chengjun , Chi Yumeng , Li Zhen , Xu Wei , Sun Tiemin
Published: July 2016

A series of bedaquiline analogs containing H-bond donors were designed as anti-Mycobacterium tuberculosis drugs. A pair of diastereoisomers (R/S- and S/S-isomers) was selected from these designed compounds for synthetic and stereochemical research. The title compounds were synthesized from chiral precursors for the first time and the absolute configurations (ACs) were determined by electronic circular dichroism (ECD) with quantum chemical calculations. Moreover, a single crystal of the S/S compound was obtained for X-ray diffraction analysis, and the crystal structure showed high consistency with the geometry, confirming the reliability of ACs obtained by ECD analyses and theoretical simulation. Furthermore, the effect of stereochemistry on the anti-tuberculosis activity was investigated. The MICs of the R/S- and S/S-isomers against Mycobacterium phlei 1180 are 9.6 and 32.1 μg·mL−1, respectively. Finally, molecular docking was carried out to evaluate the inhibitory nature and binding mode differences between diastereoisomers.
Bioelectrical Impedance Vector Analysis and Muscular Fitness in Healthy Men
Authors: Rodríguez-Rodríguez Fernando , Cristi-Montero Carlos , González-Ruíz Katherine , Correa-Bautista Jorge , Ramírez-Vélez Robinson
Published: July 2016

Muscle strength can define the general muscular fitness (MF) measurable through hand-grip strength (HG), which is a factor that relates to the health of people of different ages. In this study we evaluated the muscle strength together with a bioimpedance electric analysis in 223 healthy Colombian adult subjects. The bioelectrical impedance vector analysis (BIVA) was conducted to determine the resistance (R), reactance (Xc) and phase angle (PhA). We classified the subjects into three groups (for tertiles), obtaining lower values of R and Xc in subjects with lower HG, plus a high correlation between PhA and HG. An increase in the level of PhA is associated with a high level of MF in a sample of healthy Latin American adult men. The BIVA’s parameters and PhA are a potentially effective preventive measure to be integrated into routine screening in the clinical setting.
Heparin: Past, Present, and Future
Authors: Oduah Eziafa , Linhardt Robert , Sharfstein Susan
Published: July 2016

Heparin, the most widely used anticoagulant drug in the world today, remains an animal-derived product with the attendant risks of adulteration and contamination. A contamination crisis in 2007–2008 increased the impetus to provide non-animal-derived sources of heparin, produced under cGMP conditions. In addition, recent studies suggest that heparin may have significant antineoplastic activity, separate and distinct from its anticoagulant activity, while other studies indicate a role for heparin in treating inflammation, infertility, and infectious disease. A variety of strategies have been proposed to produce a bioengineered heparin. In this review, we discuss several of these strategies including microbial production, mammalian cell production, and chemoenzymatic modification. We also propose strategies for creating “designer” heparins and heparan-sulfates with various biochemical and physiological properties.
On the Use of a Signal Quality Index Applying at Tracking Stage Level to Assist the RAIM System of a GNSS Receiver
Authors: Berardo Mattia , Lo Presti Letizia
Published: July 2016

In this work, a novel signal processing method is proposed to assist the Receiver Autonomous Integrity Monitoring (RAIM) module used in a receiver of Global Navigation Satellite Systems (GNSS) to improve the integrity of the estimated position. The proposed technique represents an evolution of the Multipath Distance Detector (MPDD), thanks to the introduction of a Signal Quality Index (SQI), which is both a metric able to evaluate the goodness of the signal, and a parameter used to improve the performance of the RAIM modules. Simulation results show the effectiveness of the proposed method.
Exchange Bias Tuning for Magnetoresistive Sensors by Inclusion of Non-Magnetic Impurities
Authors: Sharma Parikshit , Albisetti Edoardo , Monticelli Marco , Bertacco Riccardo , Petti Daniela
Published: July 2016

The fine control of the exchange coupling strength and blocking temperature ofexchange bias systems is an important requirement for the development of magnetoresistive sensors with two pinned electrodes. In this paper, we successfully tune these parameters in top- and bottom-pinned systems, comprising 5 nm thick Co40Fe40B20 and 6.5 nm thick Ir22Mn78 films. By inserting Ru impurities at different concentrations in the Ir22Mn78 layer, blocking temperatures ranging from 220 °C to 100 °C and exchange bias fields from 200 Oe to 60 Oe are obtained. This method is then applied to the fabrication of sensors based on magnetic tunneling junctions consisting of a pinned synthetic antiferromagnet reference layer and a top-pinned sensing layer. This work paves the way towards the development of new sensors with finely tuned magnetic anisotropies.
Design of Helical Capacitance Sensor for Holdup Measurement in Two-Phase Stratified Flow: A Sinusoidal Function Approach
Authors: Lim Lam , Pao William , Hamid Nor , Tang Tong
Published: July 2016

A 360° twisted helical capacitance sensor was developed for holdup measurement in horizontal two-phase stratified flow. Instead of suppressing nonlinear response, the sensor was optimized in such a way that a ‘sine-like’ function was displayed on top of the linear function. This concept of design had been implemented and verified in both software and hardware. A good agreement was achieved between the finite element model of proposed design and the approximation model (pure sinusoidal function), with a maximum difference of ±1.2%. In addition, the design parameters of the sensor were analysed and investigated. It was found that the error in symmetry of the sinusoidal function could be minimized by adjusting the pitch of helix. The experiments of air-water and oil-water stratified flows were carried out and validated the sinusoidal relationship with a maximum difference of ±1.2% and ±1.3% for the range of water holdup from 0.15 to 0.85. The proposed design concept therefore may pose a promising alternative for the optimization of capacitance sensor design.
Ten Years of REDD+: A Critical Review of the Impact of REDD+ on Forest-Dependent Communities
Authors: Bayrak Mucahid , Marafa Lawal
Published: July 2016

The Reducing Emissions from Deforestation and Forest Degradation program, or REDD+, has been the international community’s first real attempt to create a global forest governance system which would impact countries on national, regional and even local scales. This paper provides an in-depth analysis on the impact of REDD+ on forest-dependent communities. The dimensions which are included in this review are institutions and governance, livelihoods, socio-cultural aspects, and the environment. Many studies confirm that forest-dependent communities are not sufficiently involved in current REDD+ projects. Furthermore, current and potential impacts of REDD+ on communities often disrupt local peoples’ livelihoods and strategies, institutions and socio-cultural systems in various ways, such as unequal benefit sharing, food insecurity, introduction of new powerful stakeholders, illegal land acquisition, unfair free prior and informed consent, and the introduction of monoculture plantations. REDD+ is also perceived as a neoliberal mechanism which renegotiates peoples’ relationship with the natural environment by monetizing nature. The paper concludes with a framework which addresses the potential drivers and threats of REDD+ concerning forest-dependent communities based on the literature review. This framework suggests a holistic approach to REDD+ implementation, which incorporates forest-dependent communities’ often complex relationship with the natural environment, such as incorporation of traditional forest management systems and provision of viable alternatives to loss of agricultural land.
Activation and Desensitization of Peripheral Muscle and Neuronal Nicotinic Acetylcholine Receptors by Selected, Naturally-Occurring Pyridine Alkaloids
Authors: Green Benedict , Lee Stephen , Welch Kevin , Cook Daniel , Kem William
Published: July 2016

Teratogenic alkaloids can cause developmental defects due to the inhibition of fetal movement that results from desensitization of fetal muscle-type nicotinic acetylcholine receptors (nAChRs). We investigated the ability of two known teratogens, the piperidinyl-pyridine anabasine and its 1,2-dehydropiperidinyl analog anabaseine, to activate and desensitize peripheral nAChRs expressed in TE-671 and SH-SY5Y cells. Activation-concentration response curves for each alkaloid were obtained in the same multi-well plate. To measure rapid desensitization, cells were first exposed to five potentially-desensitizing concentrations of each alkaloid in log10 molar increments from 10 nM to 100 µM and then to a fixed concentration of acetylcholine (ACh), which alone produces near-maximal activation. The fifty percent desensitization concentration (DC50) was calculated from the alkaloid concentration-ACh response curve. Agonist fast desensitization potency was predicted by the agonist potency measured in the initial response. Anabaseine was a more potent desensitizer than anabasine. Relative to anabaseine, nicotine was more potent to autonomic nAChRs, but less potent to the fetal neuromuscular nAChRs. Our experiments have demonstrated that anabaseine is more effective at desensitizing fetal muscle-type nAChRs than anabasine or nicotine and, thus, it is predicted to be more teratogenic.
Towards potential nanoparticle contrast agents: Synthesis of new functionalized PEG bisphosphonates
Authors: Kachbi-Khelfallah Souad , Monteil Maelle , Cortes-Clerget Margery , Migianu-Griffoni Evelyne , Pirat Jean-Luc , Gager Olivier , Deschamp Julia , Lecouvey Marc
Published: July 2016

The use of nanotechnologies for biomedical applications took a real development during these last years. To allow an effective targeting for biomedical imaging applications, the adsorption of plasmatic proteins on the surface of nanoparticles must be prevented to reduce the hepatic capture and increase the plasmatic time life. In biologic media, metal oxide nanoparticles are not stable and must be coated by biocompatible organic ligands. The use of phosphonate ligands to modify the nanoparticle surface drew a lot of attention in the last years for the design of highly functional hybrid materials. Here, we report a methodology to synthesize bisphosphonates having functionalized PEG side chains with different lengths. The key step is a procedure developed in our laboratory to introduce the bisphosphonate from acyl chloride and tris(trimethylsilyl)phosphite in one step.
Efficacy of Sofosbuvir plus Ribavirin in Treatment-Naive Patients with Genotype-1 and -3 HCV Infection: Results from a Russian Phase IIIb Study
Authors: Isakov Vasily , Zhdanov Konstantin , Kersey Kathryn , Svarovskaia Evguenia , Massetto Benedetta , Zhu Yanni , Knox Steven J , Bakulin Igor , Chulanov Vladimir
Published: July 2016

Background

In this Phase IIIb study, we evaluated the efficacy and safety of the oral nucleotide analogue inhibitor sofosbuvir plus ribavirin, with special attention given to viral resistance, in Russian patients with HCV geno-type-1 or -3.

Methods

Treatment-naive patients with and without compensated cirrhosis were randomized (1:1) to receive 16 or 24 weeks of once-daily sofosbuvir 400 mg plus twice-daily oral ribavirin 1,000 or 1,200 mg/day. The primary efficacy end point was the proportion of patients with sustained viral response 12 weeks after the end of treatment (SVR12). Viral resistance testing was performed by deep sequencing on all baseline samples and for patients who experienced virological failure.

Results

SVR12 rates for patients with genotype-1 HCV were 50% and 76% for those in the 16-week and 24-week groups, respectively, and for patients with geno-type-3 HCV, SVR12 rates were 87% and 90% for patients in the 16-week and 24-weeks groups, respectively. Geno-type-1 patients with the L159F resistance-associated variant who received 16 weeks of treatment had lower SVR12 rates than those without, but in patients who received 24 weeks of treatment, response rates were similar in those with and without L159F (80% versus 74%). Sofosbuvir plus ribavirin was well tolerated with no deaths, adverse event-related study drug discontinuations, or grade 3 or 4 adverse events, and few grade 3 or 4 laboratory abnormalities.

Conclusions

Sofosbuvir plus ribavirin for 16 or 24 weeks was associated with a high SVR rate in patients with HCV genotype-3. Among HCV genotype-1b patients, the presence of the L159F variant at baseline was associated with a lower SVR rate in those treated for 16 weeks but not in those treated for 24 weeks. Sofosbuvir plus ribavirin was safe and well tolerated regardless of treatment duration. Clinicaltrials.gov number NCT01896193.
Sécurité pharmaceutique, technologie et marché en Afrique
Authors: Quet Mathieu
Published: July 2016

L’article revient sur le problème public des médicaments illicites et sur les actions engagées par le gouvernement kényan pour lutter contre ce phénomène. Une attention particulière est prêtée à la reformulation récente du problème de l’illicite et à l’importance prise par les technologies dans la sécurisation du marché pharmaceutique. L’hypothèse soumise est que sous sa formulation actuelle et avec l’outillage qui l’accompagne, le problème des médicaments illicites contribue à donner une importance croissante aux standards et aux technologies de contrôle dans les débats sur l’accès aux médicaments pour les pays du Sud. L’analyse porte alors sur différentes technologies de sécurisation et sur les conceptions de l’authenticité et de la légitimité pharmaceutique qu’elles mettent en œuvre.
De la mesure au sens de la mesure
Authors: David Pierre-Marie
Published: July 2016

Pour donner sens à la mesure, il faut la rapporter à un système de valeurs qui en permet l’évaluation et le jugement. Voilà le parti pris théorique qui sous-tend cet article consacré aux pratiques d’écriture de la lutte contre le sida à partir d’une approche à l’intersection de l’anthropologie politique de la santé et du domaine des science studies. Afin d’investiguer le passage et les éventuels blocages entre la mesure et le sens de cette mesure, je vais revenir sur l’histoire de la mise en place de systèmes d’indicateurs pour accompagner les traitements du sida en République centrafricaine (RCA), un pays parmi les plus pauvres au monde et avec des capacités étatiques très faibles. L’article vise précisément à décrire et comprendre comment, dans ce contexte de grande incertitude matérielle et de violence structurelle, un système de mesure dans la lutte contre le sida s’est construit et dans un deuxième temps comment les mesures ont circulé à l’intersection du global et du local ; formant ce que nous appelons une économie scripturaire. La réflexion s’articule donc autour de deux axes. Un premier qui présentera la mise en place des pratiques, des outils de connaissances et de mesure de l’infection par le VIH en RCA. Un deuxième abordera plus particulièrement les effets inattendus des usages de la mesure : de la performance à la perte du « sens de la mesure » avec le gel des financements d’un programme vital.
La fabrique locale des statistiques scolaires
Authors: Fichtner Sarah
Published: July 2016

Fondé sur une recherche ethnographique de 12 mois dans une école primaire en zone rurale au Bénin, l’article s’intéresse aux « petits arrangements » autour de la fabrique locale des statistiques scolaires : entre exigences internationales, stratégies et marges de manœuvre locales. Au travers des exemples de deux variables clés qui informent la politique internationale de l’Éducation pour tous – l’effectif des élèves et leurs taux de redoublement – l’étude montre comment les acteurs impliqués dans l’arène scolaire font, représentent et gouvernent leur école par les chiffres. Dans cette perspective, les représentations chiffrées constituent surtout des outils de la micropolitique scolaire (notamment par rapport aux ressources budgétaires et la réputation de l’école) et de (l’auto)contrôle bureaucratique de ses acteurs, plutôt que des instruments fiables pour informer et contrôler la (macro)politique du développement.
Instrumentos y políticas de medidas en África
Authors: Cabane Lydie , Tantchou Josiane
Published: July 2016

Los instrumentos de medida se volvieron herramientas centrales en el gobierno de la África contemporánea. Siguiendo el foco en la performance económica como herramienta de reforme de la ayuda al desarrollo y de los Estados, la medida genera nuevas modalidades de intervención (experimentación, cuantificación) y de reconfiguración política. Esas herramientas moviliazn expertos y saberes específicos y ponen los Estados en posición ambigua, a la vez coaccionados par estas infraestructuras técnicas de la acción política y manipulando también su margen de manobra para afirmarse sobre su población. Crean las condiciones de una infiltración donde los financieros internacionales más que imponer condiciones e intervenir desde afuera, se involucran en los Estados africanos a través de técnicas, medidas, estandarización, evaluación y una terminología especifica.
Control of the Spring Back in Rice Husk by Al2O3 Sol
Authors: Liu Jing Jing , Li Yuan Bing , Li Shu Jing , Li Ya Wei , Sang Shao Bai
Published: July 2016

The effects of Al2O3 sol on the mechanical, morphological, and water sorption properties of rice husk were studied by means of compression-strain tester, and scanning electron microscopy (SEM) associated with the energy spectrum analysis. The results showed that the spring back of materials is found to decrease with increasing coating concentration. With the increase in Al2O3 sol concentration, the gaining of mass fraction of the materials increased proportionally, while the water absorption, which measured at ambient temperature, was gradually decreased with increasing Al2O3 sol concentrations. The gaining of mass fraction, lowest water absorption and lowest of compressive recovery ratio of 10.15%, 34.5% and 16.58%, respectively, were obtained when Al2O3 sol solid content was 8%, and resulted mainly from an increase in the rigidity increase. The Al2O3 sol had a positive effect on the morphology stabilization of rice husk.
The Influence of Al2O3 and TiO2 Additions on the Sintering Behavior of Partial Reaction Bonding Silicon Nitride
Authors: Deng Jian , Yao Dong Xu , Xia Yong Feng , Zuo Kai Hui , Liang Han Qin , Zeng Yu Ping
Published: July 2016

To compare the influence of Al2O3 and TiO2 on the sintering behavior of partial reaction bonding silicon nitride (RBSN) and post densification behavior, different amounts of Al2O3 or TiO2 have been added into Si-Si3N4-Y2O3 system. The results indicated that a high amount of Al2O3 addition inhibited the reaction bonding process, a lower nitridation degree was obtained, while TiO2 has limited influence on nitridation, only slightly decreased nitration degree with increasing TiO2 addition. After post sintered at 1800 °C, a density ranging from 2.31 to 3.09g/cm3 were obtained with additions of Al2O3 and TiO2, much larger than the one without them. The linear shrinkage of post-sintered samples was strongly promoted with high Al2O3 content, but it was irrelevant with the amount of TiO2. The highest bending strength of 523MPa can be obtained with addition of 6wt% Al2O3. TiO2 transformed into TiN which located at grain boundary interfaces, restraining the grain growth of β-Si3N4 and leading to an inferior flexural strength after post sintered at 1800 °C.
Influence of Hot Pressing Process on the Properties of Cf/SiO2 Composites
Authors: Shao Chang Tao , Wei Qi Hong , Wang Hong Sheng , Wang Chong Hai , Zhang Qing Li , Wang Ying Ying
Published: July 2016

Cf/SiO2 composites were prepared by slurry impregnation-hot pressing process, and their mechanical properties, microstructure and surface morphologies were then investigated. The results indicated that the composites showed the best mechanical properties, and the tensile strength, bending curvature, compression strength were 58MPa, 170MPa, 256MPa respectively. XRD spectrums showed that fused quartz appeared no crystallization during the process. Also from the TEM analysis, we can see that the Cf/SiO2 composites exhibited the best compactness. All the tests were carried out on the composites autoclaved at 1400°C for 60min, according to which the best hot pressing process was concluded.
Fabrication and Properties of W-SiCP/Cu Composites by Hot Pressing Sintering
Authors: Zhang Lian Meng , Liu Yao , Zhang Cheng Cheng , Luo Guo Qiang , Liu Huang , Shen Qiang
Published: July 2016

Abstract. A new ternary composite of W-SiCP/Cu(40vol%) was designed and prepared by low-temperature hot-press sintering. The micro-structural characterizations were evaluated by X-ray diffraction (XRD) and scanning electron microstructure (SEM), coefficient of thermal expansion is measured. When sintered at 950°C-100MPa-2h, the relative density of the W-SiCP/Cu composites as a function of W content all exceeded 97%. Due to the plastic deformation of Cu, higher densification W-SiCP/Cu(40vol%) composites can be achieved at a relatively low temperature. The composites are characterized by the relatively low coefficient of thermal expansion, bending strength and hardness. The values of thermal expansion indicate that thermal expansion can be precisely controlled by adding SiC particles.
Evidence of Normal to Anti Ferroelectric Phase Transition of PLZT Transparent Ceramics of Different Zr/Ti Ratio
Authors: Xia Bin , He Xi Yun , Sun Da Zhi , Cheng Wen Xiu , Qiu Ping Sun , Zeng Xia
Published: July 2016

The lanthanum-modified lead zirconate titanate transparent ceramics with different Zr/Ti ratio were prepared by the hot pressing sintering method. A single perovskive structure with a dense microsctructure was obtained and the transgranular fracture of PLZT ceramics tended to be more serious As the Zr/Ti ratio increases, the transmittance of PLZT ceramics tended to be higher and the transgranular fracture became more serious. The P-E loops changed froe a square hysteresis loop to a double tending slim hysteresis loop. Besides,the S-E loops changed from a approximate parabolic shape to a butterfly shape. These two loops confirm the transition from normal ferroelectric to anti ferroelectric phase occured with the Zr/Ti ratio increasing.
SiO2-Coated Fe-Ni Alloy Core–Shell Structures Synthesized by a Facile Chemical Method
Authors: Li Guo Jun , Mei Yun Hui , Hou Feng
Published: July 2016

Fe-Ni@ SiO2core–shell structured micrometer spherical particles with nanometer thick SiO2 shell were fabricated by a facile wet chemical process, their compositions and mechanisms were investigated using x-ray diffraction and Fourier transform of infra-red spectra, and their microstructures and magnetic properties were analyzed by high-resolution transmission electron microscopy and vibrating sample magnetometer. The structure of the synthesized SiO2-coated Fe-Ni alloy particles varied with adding TEOS contents. As-prepared Fe-Ni@SiO2 composites exhibit typical soft magnetic properties. Their highest saturation magnetization approximately linear decreases from 176 emu g−1for pure Fe-Ni alloy powders to 121 emu g−1for the coated powders with 20nm amorphous silica layers, but the coercivity of all different thickness SiO2-coated Fe-Ni alloy powders maintains in the range of about 25 Oe.
Electrical Properties of Y0.06Sr0.94Ti0.6Fe0.4O3-δ-YSZ Composites as Electrode Materials
Authors: Shan Ke , Guo Xing Min , Zhai Feng Rui , Yi Zhong Zhou
Published: July 2016

Y0.06Sr0.94Ti0.6Fe0.4O3-δ-YSZ composites were prepared by mixing Y, Fe co-doped SrTiO3 (Y0.06Sr0.94Ti0.6Fe0.4O3-δ known as YSTF) and 8 mol% Y2O3 stabilized ZrO2 (YSZ) in different weight fractions. The phase stability, phase compatibility, microstructure and mixed ionic-electronic conductivity of composites were investigated. Phase analysis by XRD showed no clearly detectable secondary phases. The electrical conductivity measurement on the YSTF-YSZ composites showed a drastic decrease in total electrical and ionic conductivities when more than 10 wt% of YSZ was used in the composites. The total electrical conductivity was 0.102 S/cm for Y0.06Sr0.94Ti0.6Fe0.4O3-δ and 0.043 S/cm for YSTF-20YSZ at 700 oC, respectively. The value at 700 oC is approximately 2.4 times higher than that of YSTF-20YSZ. The ionic conductivity of Y0.06Sr0.94Ti0.8Fe0.2O3-δ varies from 0.015S/cm at 700 oC to 0.02 S/cm at 800 oC, respectively. The value at 800°C is approximately 12.5 times higher than YSTF-20YSZ. The ion transference numbers of YSTF-YSZ composites vary from 0.14 to 0.28 at 800 °C.
Effect of the Addition of Al Power on the Microstructure and Phase Constitution of Al2O3-MgO Composites Sintered at 1700°C under N2 Atmosphere
Authors: Ma Jia Jia , Li Yong , Tong Shang Hao , Yue Dan Dan , Hong Yang
Published: July 2016

Al2O3-MgO-Al composites were prepared by sintering in carbon tube furnace at 1700°C under nitrogen atmosphere with tabular alumina, sintered magnesia and aluminum powder as raw materials. Effect of Al powder content on the porosity, microstructure and phase constitution of Al-Al2O3-MgO composites were investigated. The results show that the main phase was non-stoichiometric spinel solid solution, and a little AlN, AlON and MgAlON were detected by XRD. With Al power content increasing, the amount of the porosity and AlN, AlON and MgAlON around the porosity detected by SEM increased. These new phases enhance the combination of the large particles and the matrix.
Effect of the Addition of Al Powder on the Microstructure and Phase Constitution of Magnesia-Spinel Composites Sintered at 1800°C in N2
Authors: Hong Yang , Li Yong , Tong Shang Hao , Yue Dan Dan , Ma Jia Jia
Published: July 2016

Magnesia-spinel composites were prepared by sintering at 1800°C in N2 with fused magnesia, sintered magnesia, MgO-Al2O3 spinel as raw materials and Al powder as additive. The compositions and microstructure of sintered products were investigated by XRD and SEM. The results show that a little AlN and MgAlON has been detected by XRD and SEM, indicating that AlN and MgAlON can be synthesized at 1800°C in N2. Some Al from matrix reacts with minor O2 existing in N2 and forms gaseous Al2O at the first stage of reaction, which causes the increasing porosity of samples with more Al powder added and the limited amount of AlN and MgAlON. AlON can not be detected in the samples.
Preparation and Characterization of Mullite Fiber-Reinforced Al2O3-SiO2 Aerogel Composites
Authors: Chen Heng , Sui Xue Ye , Zhou Chang Ling , Wang Chong Hai , Yin Chang Xia , Liu Fu Tian
Published: July 2016

Mullite fiber-reinforced Al2O3-SiO2 aerogel composite was prepared through hybrid sol-gel process, vacuum pressure impregnation technology and ethanol supercritical drying technology using aluminum chloride hexahydrate (AlCl3·6H2O), tetraethoxysilane (TEOS) and mullite fiber as raw materials. The samples were characterized by XRD, SEM, BET, Hot Disk and Universal Testing Machine. The results showed that mullite fiber-reinforced Al2O3-SiO2 aerogel composite possessed excellent heat-insulation performance, high-temperature stability and mechanical property. The thermal conductivities of composite increased from 0.0186W/mK at 150°C to 0.1198W/mK at 1200°C. The surface area of Al2O3-SiO2 aerogel increased from 589m2/g at ambient temperature to 667m2/g at 600°C, and correspondingly the pore diameter increased from 21.47nm to 27.82nm. The phase of Al2O3-SiO2 aerogel was from boemite at ambient temperature to γ-Al2O3 at 600°C, and to mullite at 1200°C. The compressive strength was 1.8MPa, when the shape variables reached 10%, the tensile strength was 0.69MPa, the bending strength was 6.4MPa.
Influence of Temperature on the Order-Disorder Transition in Gd2Zr2O7
Authors: Shi Jing Lin , Qu Zhi Xue , Wang Qun
Published: July 2016

Chemical co-precipitation method was used to prepare Gd2Zr2O7 powders. The powders were then heated in air at 1500°C, 1510°C, 1525°C, 1530°C, 1550°C, 1575°C, 1600°C for 5 h, and 1575°C, 1600°C for 10 h, respectively. The samples after heat treatment were characterized by X-ray diffraction and Raman spectroscopy. X-ray diffraction patterns reveal that order-disorder transition of Gd2Zr2O7 occurs between 1550°C and 1575°C. Prior to the transition, the relative intensity of peaks corresponding to the super-lattice of pyrochlores increases with the increasing temperature. On the other hand, Raman spectra give an inconsistent result from the X-ray diffraction data. No appreciable difference can be observed for all the samples though with peaks broadening as temperature increases. The spectra of the samples indicated as fluorite structure in X-ray diffraction patterns appear with six resolvable peaks which is quite different from the spectrum of ideal fluorite structure.
Effect of h-BN on Sintering Behavior, Microstructures and Mechanical Properties of YAG Bulk Composites
Authors: Li Shi Bin , Song Jie Guang , Ru Hong Ying , Bai Xiao Bo
Published: July 2016

The shell structure YAG composite powders with different volume fraction (15, 20 and 25vol%) micro h-BN have been prepared by co-precipitation process. The bulk composites were performed by pressure sintering at 1600°C under a pressure of 30MPa in vacuum. The mechanical properties (elastic modulus, hardness, and fracture toughness) and relative density of the composites were investigated detailedly. Furthermore, phase composition and microstructure of the composites were analyzed thoroughly by X-ray diffraction, scanning electron microscopy. Meanwhile, good machinability is maintained due to the low hardness of the second phase.
Preparation and Properties of Phenolic Resin Impregnated Quartz Fiber Tile Ablative Composite
Authors: Sun Yang , Shi Li Ping , Zhou Chang Ling , Wang Chong Hai , Xu Hong Zhao
Published: July 2016

To improve the heat absorbed and scattered properties of quartz fiber tile, porous phenolic resin impregnated quartz fiber tile composite for ablator and thermal insulator was prepared by impregnating the quartz fiber tile with ethanol solution of phenolic resin, and then drying and cured. The phenolic resin impregnated quartz fiber tile ablative composite is a new heat protection composite material with lower density, lower heat conductivity and low mass ablation. It can be used as the widespread thermal protection system of the aero craft in the high heat flux, high temperature and extreme condition. The thermal property and ablation property of the composites were studied respectively. The ablation property of PICA was evaluated by the oxyacetylene ablation experiment. The microstructure morphology of specimen before and after ablation was viewed by SEM. The thermogravimetric analysis of the ablator was taken from room temperature to 800°C.
Performance of Nano-Silica Insulation Material Enhanced by High Humidity-Reinforcement Method
Authors: Zhang Shi Chao , Chen Yu Feng , Wu Wei , Sun Hao Ran , Wang Guang Hai , Sun Xian Kai , Fang Kai , Zhang Feng
Published: July 2016

In this paper, fumed nano-silica as the main raw material, nano-silica insulation materials were prepared by the dry processing. Research on humidity-reinforcement of nano-Silica insulation materials has been carried out and analyzed. When hygroscopicity of samples reach to 23%, the compressive strength 1.65MPa is at twice the one without high humidity-reinforcement, while the thermal conductivities are almost the same. Then, the action mechanism of high humidity-reinforcement method was analyzed. In humidity-reinforcement method, as vapor enters, silica sol is formed in the gap between one aggregate particle and another, and various condensation polymerization occurred in the drying process, which lead to aggregates connection and compressive strength improvement.
Effects of Concentrations of NaCl on the Sintering and Thermal Conductivity of Forsterite
Authors: Ding Jun , Zhu Hong Xi , Deng Cheng Ji , Guo Ding , Shang Heng
Published: July 2016

This paper aims to study the effects of NaCl on the sintering of forsterite as well as the thermal conductivity of the sintering products. In the sintering process, NaCl played a role in the system by mainly providing a liquid phase sintering environment in order to promote grain growth and forsterite sintering. Moreover, the model of liquid phase sintering was established in this paper. In the initial sintering stage, the phenomenon of particle re-arrangement was not significant, and dissolution-precipitation was regarded as the dominant sintering mechanism. With the extension of the sintering time, the middle and later stages of the sintering process were mainly controlled by the diffusion mechanism. A test of the thermal conductivity of samples with 40% and 50% NaCl was carried out, which indicated that the thermal conductivity of the two samples ranged from 0.3 to 0.4 W·m-1·k-1. At the same temperatures, the thermal conductivity of the sample with a salt content of 50% was lower than that of the sample with a salt concentration of 40%. Also, the heat insulation effect of the sample with a salt content of 50% was better than that of the sample of 40% . Hence, it can be concluded that the higher the salt content in the sample, the lower the thermal conductivity of the sample.
Fabrication of Mullite Coating and its Oxidation Protection for Carbon Fiber Reinforced SiC Composites
Authors: Zeng Kuan Hong , Ma Qing Song , Cai Li Hui
Published: July 2016

To protect carbon fiber-reinforced SiC (C/SiC) composites against oxidation,mullite coating was prepared on C/SiC composites by dip-coating method with high solid content Al2O3-SiO2 sol as raw materials. X-ray diffraction and scanning electron microscopy were employed to analyze the phase and microstructure of the coating. The results show that the as-prepared coating is SiO2-rich, monolithic and well bonded with substrate without penetrating crack, giving rise to good oxidation-resistance. After soaked at 1400°C for 30min under static air, the coated C/SiC composites possess 87% of original flexural strength. As a result of sealing and filling of cracks and pores by viscous SiO2 in coating, the coated C/SiC composites exhibit improved oxidation resistance at 1500°C and 1600°C. There is no change in flexural strength after oxidized at 1500°C and 1600°C for 30min, respectively. Nevertheless, the carbothermal reduction between viscous SiO2 and free carbon in C/SiC substrate would occur obviously when oxidation temperature was elevated or oxidation time was prolonged, leading to local foaming in coating and decreasing in oxidation resistance.
Synthesis of Ultra-Fine Zirconium Diboride Powders by Polymer Template Method Following by Microwave Sintering
Authors: Deng Qi Huang , Ding Zhi Hui , Shen Xiang Feng , Du Shi Yu , Huang Qing
Published: July 2016

Zirconium diboride (ZrB2) nanoparticles were synthesized by polymer template method using zirconyl (ZrOCl2∙8H2O), boric acid (H3BO3), Chitosan and Mannitol (C6H14O6) with microwave sintering method. SEM and other analytic methods were used to study the phase composition and the microstructure of the nanoparticles.The influence of the ratio of zirconium to boron and carbon on the purity of ZrB2 powders, as well as the synthesis temperature and the holding time were studied. Pure ZrB2 at the molar ratio of C/Zr/B=10/5.2/1 can be obtained. The optimum parameter for microwave sintering is 1320 °C for 1h, which is about 300°C lower than conventional carbonization reduction to obtain ZrB2 powders. The synthesized powders have small particle sizes (50nm) with nearly spherical morphology.
Microstructure and Mechanical Properties of ZrB2/h-BN Multiphase Ceramics by Low-Temperature Reactive Sintering
Authors: Zhai Feng Rui , Shan Ke , Xu Ruo Meng , Lu Min , Yi Zhong Zhou , Xie Zhi Peng
Published: July 2016

In the present paper, the ZrB2/h-BN multiphase ceramics were fabricated by SPS (spark plasma sintering) technology at lower sintering temperature using h-BN, ZrO2, AlN and Si as raw materials and B2O3 as a sintering aid. The phase constitution and microstructure of specimens were analyzed by XRD and SEM. Moreover, the effects of different sintering pressures on the densification, microstructure and mechanical properties of ZrB2/h-BN multiphase ceramics were also systematically investigated. The results show that the ZrB2 was obtained through solid phase reaction at different sintering pressures, and increasing sintering pressure could accelerate the formation of ZrB2 phase. As the sintering pressure increasing, the fracture strength and toughness of the sintered samples had a similar increasing tendency as the relative density. The better comprehensive properties were obtained at given sintering pressure of 50MPa, and the relative density, fracture strength and toughness reached about 93.4%, 321MPa and 3.3MPa·m1/2, respectively. The SEM analysis shows that the h-BN grains were fine and uniform, and the effect of sintering pressure on grain size was inconspicuous. The distribution of grain is random cross array, and the fracture texture was more obvious with the increase of sintering pressure. The fracture mode of sintered samples remained intergranular fracture mechanism as sintering pressure changed, and the grain refinement, grain pullout and crack deflection helped to increase the mechanical properties.
Microstructures and Mechanical Properties of β-Sialon-cBN Composites
Authors: Wu Xin Ze , Wu Yi , Han Jin Long , Shen Tian Yu
Published: July 2016

β-Sialon-cubic boron nitride (cBN) composites were prepared by the high temperature (1700°C) and high pressure (5GPa) sintering. β-Sialon chemical general composition can be represented as Si6-zAlzOzN8 –z (Z is the number of Al atoms which are substituted by Si atoms, and the range of z value is usually between 0-4.2[1].).The effects of different formula with corresponding to z values on microstructure and mechanical properties of β-Sialon-cBN composites were studied. The relative test results were verified by computer simulation. The study result showed: with the z values of β-Sialon increasing, the aluminum and oxygen content increased. The densification and mechanical properties of β-Sialon-cBN composites decreased gradually.