bluuebunny/crossref_metadata_2025 huggingface dataset:
Neuroprotective and Cognitive Enhancement Potentials of Baicalin: A Review
Authors: Sowndhararajan Kandhasamy , Deepa Ponnuvel , Kim Minju , Park Se , Kim Songmun
Published: June 2018

Neurodegenerative diseases are a heterogeneous group of disorders that are characterized by the gradual loss of neurons. The development of effective neuroprotective agents to prevent and control neurodegenerative diseases is specifically important. Recently, there has been an increasing interest in selecting flavonoid compounds as potential neuroprotective agents, owing to their high effectiveness with low side effects. Baicalin is one of the important flavonoid compounds, which is mainly isolated from the root of Scutellaria baicalensis Georgi (an important Chinese medicinal herb). In recent years, a number of studies have shown that baicalin has a potent neuroprotective effect in various in vitro and in vivo models of neuronal injury. In particular, baicalin effectively prevents neurodegenerative diseases through various pharmacological mechanisms, including antioxidative stress, anti-excitotoxicity, anti-apoptotic, anti-inflammatory, stimulating neurogenesis, promoting the expression of neuronal protective factors, etc. This review mainly focuses on the neuroprotective and cognitive enhancement effects of baicalin. The aim of the present review is to compile all information in relation to the neuroprotective and cognitive enhancement effects of baicalin and its molecular mechanisms of action in various in vitro and in vivo experimental models.
Depressive Symptoms and Self-Esteem in White and Black Older Adults in the United States
Authors: Assari Shervin , Moghani Lankarani Maryam
Published: June 2018

Background. Poor self-esteem is a core element of depression. According to recent research, some racial groups may vary in the magnitude of the link between depression and poor self-esteem. Using a national sample, we compared Black and White older Americans for the effect of baseline depressive symptoms on decline in self-esteem over time. Methods. This longitudinal study used data from the Religion, Aging, and Health Survey, 2001–2004. The study followed 1493 older adults (734 Black and 759 White) 65 years or older for three years. Baseline depressive symptoms (CES-D), measured in 2001, was the independent variable. Self-esteem, measured at the end of the follow up, was the dependent variable. Covariates included baseline demographic characteristics (age and gender), socioeconomic factors (education, income, and marital status), health (self-rated health), and baseline self-esteem. Race/ethnicity was the moderator. Linear multi-variable regression models were used for data analyses. Results. In the pooled sample, higher depressive symptoms at baseline were predictive of a larger decline in self-esteem over time, net of covariates. We found a significant interaction between race/ethnicity and baseline depressive symptoms on self-esteem decline, suggesting a weaker effect for Blacks compared to Whites. In race/ethnicity-specific models, high depressive symptoms at baseline was predictive of a decline in self-esteem for Whites but not Blacks. Conclusion. Depressive symptoms may be a more salient contributor to self-esteem decline for White than Black older adults. This finding has implications for psychotherapy and cognitive behavioral therapy of depression of racially diverse populations.
TGF-β in T Cell Biology: Implications for Cancer Immunotherapy
Authors: Dahmani Amina , Delisle Jean-Sébastien
Published: June 2018

Transforming Growth Factor beta (TGF-β) is a pleiotropic cytokine produced in large amounts within cancer microenvironments that will ultimately promote neoplastic progression, notably by suppressing the host’s T-cell immunosurveillance. This effect is mostly due to the well-known inhibitory effect of TGF-β on T cell proliferation, activation, and effector functions. Moreover, TGF-β subverts T cell immunity by favoring regulatory T-cell differentiation, further reinforcing immunosuppression within tumor microenvironments. These findings stimulated the development of many strategies to block TGF-β or its signaling pathways, either as monotherapy or in combination with other therapies, to restore anti-cancer immunity. Paradoxically, recent studies provided evidence that TGF-β can also promote differentiation of certain inflammatory populations of T cells, such as Th17, Th9, and resident-memory T cells (Trm), which have been associated with improved tumor control in several models. Here, we review current advances in our understanding of the many roles of TGF-β in T cell biology in the context of tumor immunity and discuss the possibility to manipulate TGF-β signaling to improve cancer immunotherapy.
Performance of Helical Ribbon and Screw Impellers for Mixing Viscous Fluids in Cylindrical Reactors
Authors: Ameur Houari , Kamla Youcef , Sahel Djamel
Published: June 2018

The present paper deals with the mixing of a highly viscous fluid by close-clearance impellers in cylindrical vessels. The study is performed via numerical simulations. Calculations are achieved by the discretization of continuity and momentum equations with the finite volume method. The effect of blade diameter and its shape on the well-stirred region size and the power consumption is investigated. For highly viscous fluids, the obtained results suggest the use of impellers rotating at low Reynolds number, and having a blade with the same shape of the tank to ensure mixing near the vessel base. A comparison is made between the performance of a simple helical ribbon (HR), a simple small screw (SS), helical ribbon-small screw (HR-SS) and a large screw (LS) impeller. The predicted results allow the following classification of impellers studied, based on less power requirements and small size of well-agitated region: SS < HR < HR-SS < LS.
On the Activity Enhancing Role of Iron Oxide for Noble Metal Oxidation Catalysts: A CVD-Based Study with Differently Structured Combinations of Pt and FeOx Coatings on Al2O3
Authors: Pasin Laila , Meyer Jörg , Eiche Elisabeth , Kasper Gerhard
Published: June 2018

With regard to the catalysis of oxidation reactions by noble metals, the addition of FeOx to an Al2O3-supported Pt catalyst is known to be energetically more favorable compared to only Pt. In this work, different process routes for the preparation of such Fe-promoted Pt/Al2O3 catalysts via atmospheric chemical vapor deposition (CVD) in a fluidized bed were explored. Specifically, the question of whether it would be advantageous to deposit the Fe before, along with, or after the Pt was addressed, and new information was obtained about the optimum FeOx–Pt interface and mixing ratio. Vapors of Trimethyl(methylcyclopentadienyl)platinum(IV) and/or Ethyl-ferrocene were injected into the bed from the top, permitting a quasi-lossless precursor operation and a very good control of the deposited metal, and hence of the catalyst structure. Samples could be extracted from the top while CVD was ongoing to obtain time-resolved data. The catalytic activity was determined through CO oxidation. The Fe-Pt mixing ratio was then varied for the most active deposition sequence, in order to identify an activity optimum generated by the minimum amount of Pt catalyst. When compared to pure Pt/Al2O3, the optimum catalyst consistently showed superior performance even after thermal stress.
Impact of Tree Growth Rate on the Mechanical Properties of Douglas Fir Lumber in Belgium
Authors: Henin Jean-Marc , Pollet Caroline , Jourez Benoit , Hébert Jacques
Published: June 2018

In the context of questioning the relevance of making Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) silviculture more dynamic in Wallonia, we evaluated the influence of growth rate on the potential of Douglas-fir lumber for structural uses. Therefore, six trees 120 to 180 cm in circumference at 1.5 m were felled in 11 stands whose age varied from 40 to 69 years (mean circumference of the trees ≈150 cm; initial planting density from ≈2200 to 4400 seedlings/ha). In total, 706 boards (38 × 100 mm² and 70 × 180 mm² in cross section) were cut from these trees, whose average ring width ranged between 3 and 7 mm. The density of the wood (ρ) always appeared compatible with the mechanical class C30, regardless of the growth rate of the trees from which the lumber originated. The modulus of elasticity (E) and the modulus of rupture (fm) displayed by the 38 × 100 mm² boards cut from corewood were respectively 30% and 41% lower than those observed in outerwood. The latter did not seem affected by growth rate: E and fm characteristic values remained compatible with structural use, regardless of the mean ring width. Growth rate considerably affects the characteristic values of these mechanical properties when boards are made from corewood. Juvenile growth should therefore be limited.
Changes in Topsoil Properties after Centennial Scots Pine Afforestation in a European Beech Forest (NE Spain)
Authors: Girona-García Antonio , Badía-Villas David , Martí Clara
Published: June 2018

In this work, we studied the effects of centenary Scots pine (Pinus sylvestris L.) afforestation on topsoil properties conducted in a deforested area that was previously occupied by a natural European beech (Fagus sylvatica L.) forest. Organic layers and topsoil Ah mineral horizons (0–10 cm) were sampled in the Scots pine and European beech forests of Moncayo Natural Park (north-eastern Spain). The physical (stoniness, aggregate stability, and water repellency persistence and intensity), chemical (total organic C, total N, C/N, pH, and exchangeable Ca2+, Mg2+, Na+, K+, Al3+, and Fe3+), and physicochemical (cation exchange capacity) properties of soil were analyzed. Total organic C and N were also obtained for litter samples. The studied topsoils shared a series of common properties, such as a high stoniness and aggregate stability, very low base content, high cation exchange capacity, and extreme acidity. Soils that developed under the pinewood showed a higher soil water repellency intensity. However, K+ content was significantly higher in the beechwood soil. In both forest types, total organic C and N were similar in topsoil and litter (Hemimoder type), although C and N were pooled in different O-layers. Results indicate that pine afforestation in a deforested area was an adequate measure for soil protection since it did not show significant differences in the long term (ca. 100 years) compared to the nearby natural beech stands.
Reproductive Biology of Puntius sophore in Bangladesh
Authors: Hasan Tajmira , Hossain Md. , Mamun Md. , Alam Md. , Salam Mohammad , Rafiquzzaman S.
Published: June 2018

Pool barb (Puntius sophore) is an important small indigenous species of Bangladesh, belonging to the family Cyprinidae of the order Cypriniformes. The main objectives of the present study were to identify the breeding season of Pool barb through observation of the gonadosomatic index (GSI), fecundity, oocytes diameter, and gonadal histology of the species. GSI was calculated and fecundity was determined by the gravimetric method. Interestingly, the highest value of GSI was 15.43 ± 2.20 for the month of April at Gazipur while it was 15.60 ± 1.74 in June for Jessore. In Gazipur, the highest fecundity (5053 ± 878.27) was recorded in the month of April and the highest fecundity (5433 ± 968.26) was recorded in the month of June for Jessore. Histology of the ovary of Pool barb shows the presence of early and late perinucleolar stage of oocytes during March indicating immature oocyte. Histological data revealed that the spawning season of Pool barb starts from March to July with a peak during April to May for Gazipur region and May to July for Jessore region. Finally, these results can be concluded that breeding season may vary from region to region due to environmental as well as other factors.
Impact of Standardized Prenatal Clinical Training for Traditional Birth Attendants in Rural Guatemala
Authors: Hernandez Sasha , Oliveira Jessica , Jones Leah , Chumil Juan , Shirazian Taraneh
Published: June 2018

In low-and-middle-income countries (LMICs), traditional birth attendant (TBA) training programs are increasing, yet reports are limited on how those programs affect the prenatal clinical abilities of trained TBAs. This study aims to assess the impact of clinical training on TBAs before and after a maternal health-training program. A prospective observational study was conducted in rural Guatemala from March to December 2017. Thirteen participants conducted 116 prenatal home visits. Data acquisition occurred before any prenatal clinical training had occurred, at the completion of the 14-week training program, and at six months post program completion. The paired t-test and McNemar’s test was used and statistical analyses were performed with R Version 3.3.1. There was a statistically significant improvement in prenatal clinical skills before and after the completion of the training program. The mean percentage of prenatal skills done correctly before any training occurred was 25.8%, 62.3% at the completion of the training program (p-value = 0.0001), and 71.0% after six months of continued training (p-value = 0.034). This study highlights the feasibility of prenatal skill improvement through a standardized and continuous clinical training program for TBAs. The improvement of TBA prenatal clinical skills could benefit indigenous women in rural Guatemala and other LMICs.
Factors Correlated with Success Rate of Outpatient Smoking Cessation Services in Taiwan
Authors: Huang Wei-Hsin , Hsu Hsin-Yin , Chang Betty Chia-Chen , Chang Fong-Ching
Published: June 2018

Smoking is the leading cause of preventable death. The purpose of this study was to explore the patient’s and physician’s factors that are correlated with smoking cessation success rate. A total of 877 smokers who visited the outpatient smoking cessation services at a medical center in Northern Taiwan were recruited for the study. Phone interviews were carried out six months after the initial visit to evaluate the success rate of smoking cessation. The result showed that the abstinence rate at six-month was 37.7%. By the multivariate logistic regression model, the predictive factors of abstinence were smokers who had a lower Fagerström test for cigarette dependence (FTCD), lower exhaled carbon monoxide (CO) concentration, or who smoked less than 20 cigarettes per day at the first visit. Smokers who had more than one smoking cessation outpatient visit or seen by physicians who, on average, delivered more than one smoking cessation consultations per week also led to a higher success rate. Therefore, we suggest that physicians should put more efforts and encourage follow-up visits for some smokers by knowing their characteristics at the first visit. Furthermore, physicians with more experience in smoking cessation consultation seemed to be more likely to help patients to quit smoking successfully.
Potential Health Risk of Endocrine Disruptors in Construction Sector and Plastics Industry: A New Paradigm in Occupational Health
Authors: Fucic Aleksandra , Galea Karen S. , Duca Radu Corneliu , El Yamani Mounia , Frery Nadine , Godderis Lode , Halldorsson Thórhallur Ingi , Iavicoli Ivo , Ndaw Sophie , Ribeiro Edna , Viegas Susana , Moshammer Hanns
Published: June 2018

Endocrine disruptors (EDs) belong to large and diverse groups of agents that may cause multiple biological effects associated with, for example, hormone imbalance and infertility, chronic diseases such as diabetes, genome damage and cancer. The health risks related with the exposure to EDs are typically underestimated, less well characterized, and not regulated to the same extent as, for example, carcinogens. The increased production and utilization of identified or suspected EDs in many different technological processes raises new challenges with respect to occupational exposure settings and associated health risks. Due to the specific profile of health risk, occupational exposure to EDs demands a new paradigm in health risk assessment, redefinition of exposure assessment, new effects biomarkers for occupational health surveillance and definition of limit values. The construction and plastics industries are among the strongest economic sectors, employing millions of workers globally. They also use large quantities of chemicals that are known or suspected EDs. Focusing on these two industries, this short communication discusses: (a) why occupational exposure to EDs needs a more specific approach to occupational health risk assessments, (b) identifies the current knowledge gaps, and (c) identifies and gives a rationale for a future occupational health paradigm, which will include ED biomarkers as a relevant parameter in occupational health risk assessment, surveillance and exposure prevention.
Impact of Referral Sources and Waiting Times on the Failure to Quit Smoking: One-Year Follow-Up of an Italian Cohort Admitted to a Smoking Cessation Service
Authors: Borsari Lucia , Storani Simone , Malagoli Carlotta , Filippini Tommaso , Tamelli Marco , Malavolti Marcella , Nicolini Fausto , Vinceti Marco
Published: June 2018

In Italy, the National Health Service offers specialized evidence-based support to smokers who would like to quit through smoking cessation (SC) services. We conducted a two-year prospective study, involving all 288 subjects treated for smoking cessation at the SC service of Reggio Emilia, to assess the association of referral sources and waiting times with the risk of treatment failure, by following participants up to one year after the quit date. We performed Cox-regression analysis, including demographic and smoking-related characteristics as confounding variables. The treatment failure rate at 12 months was 59.4% (171/288), including only 12 subjects lost to follow-up. The main mode of entry was self-referral (42.4%), followed by 32.6% from general practice, 17.4% from hospital and 7.6% from other sources. Only 27.8% participants were involved in the SC-program within 60 days of the first contact, as the guidelines suggest. The risk of treatment failure at 12 months showed little association with the type of referral source, while it correlated with waiting times ≥ 60 days (hazard ratio = 1.59; 95% confidence interval 1.10–2.29). This study provides evidence of long-term high quit rates from a SC service, with few subjects lost to follow-up and biochemical verification of almost all abstinent subjects. Timeliness in care provision could further improve the outcome.
Role of Magnesium Deficiency in Promoting Atherosclerosis, Endothelial Dysfunction, and Arterial Stiffening as Risk Factors for Hypertension
Authors: Kostov Krasimir , Halacheva Lyudmila
Published: June 2018

Arterial hypertension is a disease with a complex pathogenesis. Despite considerable knowledge about this socially significant disease, the role of magnesium deficiency (MgD) as a risk factor is not fully understood. Magnesium is a natural calcium antagonist. It potentiates the production of local vasodilator mediators (prostacyclin and nitric oxide) and alters vascular responses to a variety of vasoactive substances (endothelin-1, angiotensin II, and catecholamines). MgD stimulates the production of aldosterone and potentiates vascular inflammatory response, while expression/activity of various antioxidant enzymes (glutathione peroxidase, superoxide dismutase, and catalase) and the levels of important antioxidants (vitamin C, vitamin E, and selenium) are decreased. Magnesium balances the effects of catecholamines in acute and chronic stress. MgD may be associated with the development of insulin resistance, hyperglycemia, and changes in lipid metabolism, which enhance atherosclerotic changes and arterial stiffness. Magnesium regulates collagen and elastin turnover in the vascular wall and matrix metalloproteinase activity. Magnesium helps to protect the elastic fibers from calcium deposition and maintains the elasticity of the vessels. Considering the numerous positive effects on a number of mechanisms related to arterial hypertension, consuming a healthy diet that provides the recommended amount of magnesium can be an appropriate strategy for helping control blood pressure.
Cytotoxicity of Plant-Mediated Synthesis of Metallic Nanoparticles: A Systematic Review
Authors: Hanan Nurul Akma , Chiu Hock Ing , Ramachandran Muggundha Raoov , Tung Wai Hau , Mohamad Zain Nur Nadhirah , Yahaya Noorfatimah , Lim Vuanghao
Published: June 2018

In the field of medicine, nanomaterials, especially those derived using the green method, offer promise as anti-cancer agents and drug carriers. However, the biosafety of metallic nanoparticles used as anti-cancer agents remains a concern. The goal of this systematic review was to compare the cytotoxicity of different plant-mediated syntheses of metallic nanoparticles based on their potency, therapeutic index, and cancer cell type susceptibility in the hopes of identifying the most promising anti-cancer agents. A literature search of electronic databases including Science Direct, PubMed, Springer Link, Google Scholar, and ResearchGate, was conducted to obtain research articles. Keywords such as biosynthesis, plant synthesis, plant-mediated, metallic nanoparticle, cytotoxicity, and anticancer were used in the literature search. All types of research materials that met the inclusion criteria were included in the study regardless of whether the results were positive, negative, or null. The therapeutic index was used as a safety measure for the studied compound of interest. Data from 76 selected articles were extracted and synthesised. Seventy-two studies reported that the cytotoxicity of plant-mediated synthesis of metallic nanoparticles was time and/or dose-dependent. Biosynthesised silver nanoparticles demonstrated higher cytotoxicity potency compared to gold nanoparticles synthesised by the same plants (Plumbago zeylanica, Commelina nudiflora, and Cassia auriculata) irrespective of the cancer cell type tested. This review also identified a correlation between the nanoparticle size and morphology with the potency of cytotoxicity. Cytotoxicity was found to be inversely proportional to nanoparticle size. The plant-mediated syntheses of metallic nanoparticles were predominantly spherical or quasi-spherical, with the median lethal dose of 1–20 µg/mL. Nanoparticles with other shapes (triangular, hexagonal, and rods) were less potent. Metallic nanoparticles synthesised by Abutilon inducum, Butea monosperma, Gossypium hirsutum, Indoneesiella echioides, and Melia azedarach were acceptably safe as anti-cancer agents, as they had a therapeutic index of >2.0 when tested on both cancer cells and normal human cells. Most plant-mediated syntheses of metallic nanoparticles were found to be cytotoxic, although some were non-cytotoxic. The results from this study suggest a focus on a selected list of potential anti-cancer agents for further investigations of their pharmacodynamic/toxicodynamic and pharmacokinetic/toxicokinetic actions with the goal of reducing the Global Burden of Diseases and the second leading cause of mortality.
A 5D Building Information Model (BIM) for Potential Cost-Benefit Housing: A Case of Kingdom of Saudi Arabia (KSA)
Authors: Alrashed Ibrahim , Kantamaneni Komali
Published: June 2018

The Saudi construction industry is going through a process of acclimatizing to a shifting fiscal environment. Due to recent fluctuations in oil prices, the Saudi construction sector decided to adjust to current trade-market demands and rigorous constitutional regulations because of competitive pressures. This quantitative study assesses and compares existing flat design vs. mid-terrace housing through cost estimation and design criteria that takes family privacy into consideration and meets the needs of Saudi Arabian families (on average consisting of seven members). Five pilot surveys were undertaken to evaluate the property preference type of Saudi families. However, Existing models did not satisfy the medium range family needs and accordingly a 5D (3D + Time + Cost) Building Information Modelling (BIM) is proposed for cost benefiting houses. Research results revealed that mid-terrace housing was the best option, as it reduced land usage and construction costs. While, 5D BIM led to estimate accurate Bill of Quantities (BOQ) and the appraisal of construction costs.
Dispersion Stability and Lubrication Performance Correlation of Vegetable Oil-In-Water Emulsions with Nanoparticle-Shielded Oil Droplets
Authors: Taheri Reza , Kosasih Buyung , Zhu Hongtao , Tieu Anh Kiet
Published: June 2018

Vegetable oil-in-water (VO/W) emulsions are bio-based metal working lubricants. The emulsions’ lubrication performance depends on the stability of oil droplets. In this paper, the oil droplets’ dispersion stability and lubrication of emulsions containing TiO2/SiO2 nanoparticles (NPs) as dispersant and lubrication agents have been investigated. Enhanced dispersion of NP-shielded oil droplets was found. Increasing the NPs’ mass fraction initially lowers the average size of NP-shielded droplets up to the saturation of the droplets’ surface with NPs at 0.5 wt % mass fraction. NPs also form NP agglomerates in emulsions, more so after the droplets’ surfaces have been saturated with NPs. There is an apparent minimum quantity of NPs (~0.5 wt %) required to ensure sustained dispersions of the droplets which is thought to be related to the oil concentration and the droplets’ total surface-area-to-volume ratio. Below the required quantity of NPs, partially shielded and fully shielded droplets coexist. The partially shielded droplets initially attract other droplets and undergo limited coalescence but retain their long-term stability. A small quantity of NPs improves the antiwear property of the lubricants. However, emulsions with NPs have slightly higher friction than the NP-free emulsion due to the reduced strength of the tribofilm. Despite the increased friction, the tribofilm formed in presence of NPs can easily be removed from the surface with water, indicating cleaner surfaces after the lubrication (i.e., less oil residue on the surfaces), which, for the sake of cleanliness, is favourable in many applications.
Nanoscale Electrical Potential and Roughness of a Calcium Phosphate Surface Promotes the Osteogenic Phenotype of Stromal Cells
Authors: Khlusov Igor A. , Dekhtyar Yuri , Sharkeev Yurii P. , Pichugin Vladimir F. , Khlusova Marina Y. , Polyaka Nataliya , Tyulkin Fedor , Vendinya Viktorija , Legostaeva Elena V. , Litvinova Larisa S. , Shupletsova Valeria V. , Khaziakhmatova Olga G. , Yurova Kristina A. , Prosolov Konstantin A.
Published: June 2018

Mesenchymal stem cells (MSCs) and osteoblasts respond to the surface electrical charge and topography of biomaterials. This work focuses on the connection between the roughness of calcium phosphate (CP) surfaces and their electrical potential (EP) at the micro- and nanoscales and the possible role of these parameters in jointly affecting human MSC osteogenic differentiation and maturation in vitro. A microarc CP coating was deposited on titanium substrates and characterized at the micro- and nanoscale. Human adult adipose-derived MSCs (hAMSCs) or prenatal stromal cells from the human lung (HLPSCs) were cultured on the CP surface to estimate MSC behavior. The roughness, nonuniform charge polarity, and EP of CP microarc coatings on a titanium substrate were shown to affect the osteogenic differentiation and maturation of hAMSCs and HLPSCs in vitro. The surface EP induced by the negative charge increased with increasing surface roughness at the microscale. The surface relief at the nanoscale had an impact on the sign of the EP. Negative electrical charges were mainly located within the micro- and nanosockets of the coating surface, whereas positive charges were detected predominantly at the nanorelief peaks. HLPSCs located in the sockets of the CP surface expressed the osteoblastic markers osteocalcin and alkaline phosphatase. The CP multilevel topography induced charge polarity and an EP and overall promoted the osteoblast phenotype of HLPSCs. The negative sign of the EP and its magnitude at the micro- and nanosockets might be sensitive factors that can trigger osteoblastic differentiation and maturation of human stromal cells.
Protective Carbon Overlayers from 2,3-Naphthalenediol Pyrolysis on Mesoporous SiO2 and Al2O3 Analyzed by Solid-State NMR
Authors: Duan Pu , Cao Xiaoyan , Pham Hien , Datye Abhaya , Schmidt-Rohr Klaus
Published: June 2018

Hydrothermally stable carbon overlayers can protect mesoporous oxides (SiO2 and Al2O3) from hydrolysis during aqueous-phase catalysis. Overlayers made at 800 °C by pyrolysis of 2,3-naphthalenediol deposited out of acetone solution were analyzed by solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. Power absorption due to sample conductivity was prevented by diluting the sample in nonconductive and background-free tricalcium phosphate. While pyrolysis on SiO2 produced a predominantly aromatic carbon film, at least 15% of nonaromatic carbon (sp3-hybridized C as well as C=O) was observed on γ-Al2O3. These species were not derived from residual solvent, according to spectra of the same material treated at 400 °C. The sp3-hybridized C exhibited weak couplings to hydrogen, short spin-lattice relaxation times, and unusually large shift anisotropies, which are characteristics of tetrahedral carbon with high concentrations of unpaired electrons. Moderate heat treatment at 400 °C on SiO2 and Al2O3 resulted in yellow-brown and nearly black samples, respectively, but the darker color on Al2O3 did not correspond to more extensive carbonization. Aromatic carbon bonded to hydrogen remained predominant and the peaks of naphthalenediol were still recognizable; however, some of the chemical shifts differed by up to 5 ppm, indicating significant differences in local structure. On SiO2, additional sharp peaks were detected and attributed to 1/3 of the 2,3-naphthalene molecules undergoing fast, nearly isotropic motions.
Investigation of the Microstructure and Mechanical Properties of Copper-Graphite Composites Reinforced with Single-Crystal α-Al2O3 Fibres by Hot Isostatic Pressing
Authors: Zhang Guihang , Jiang Xiaosong , Qiao ChangJun , Shao Zhenyi , Zhu Degui , Zhu Minhao , Valcarcel Victor
Published: June 2018

Single-crystal α-Al2O3 fibres can be utilized as a novel reinforcement in high-temperature composites owing to their high elastic modulus, chemical and thermal stability. Unlike non-oxide fibres and polycrystalline alumina fibres, high-temperature oxidation and polycrystalline particles boundary growth will not occur for single-crystal α-Al2O3 fibres. In this work, single-crystal α-Al2O3 whiskers and Al2O3 particles synergistic reinforced copper-graphite composites were fabricated by mechanical alloying and hot isostatic pressing techniques. The phase compositions, microstructures, and fracture morphologies of the composites were investigated using X-ray diffraction, a scanning electron microscope equipped with an X-ray energy-dispersive spectrometer (EDS), an electron probe microscopic analysis equipped with wavelength-dispersive spectrometer, and a transmission electron microscope equipped with EDS. The mechanical properties have been measured by a micro-hardness tester and electronic universal testing machine. The results show that the reinforcements were unevenly distributed in the matrix with the increase of their content and there were some micro-cracks located at the interface between the reinforcement and the matrix. With the increase of the Al2O3 whisker content, the compressive strength of the composites first increased and then decreased, while the hardness decreased. The fracture and strengthening mechanisms of the composite materials were explored on the basis of the structure and composition of the composites through the formation and function of the interface. The main strengthening mechanism in the composites was fine grain strengthening and solid solution strengthening. The fracture type of the composites was brittle fracture.
Magnetic Properties and Spontaneous Polarization of La-, Mn- and N-Doped Tetragonal BiFeO3: A First-Principles Study
Authors: Tan Qiuhong , Wang Qianjin , Liu Yingkai
Published: June 2018

Multiferroic materials have been receiving attention for their potential applications in multifunctional devices. Chemical substitution is an effective method for improving the physical properties of BiFeO3 (BFO). However, different experimental results have been reported for Lanthanum- (La-) and Manganese (Mn) -doped BFO ceramics. Here, we systematically studied the magnetic properties and spontaneous polarization of La-, Mn-, and Nitrogen (N) -doped tetragonal BiFeO3 using density functional theory with the generalized gradient approximation and U-value method. The calculated results demonstrated that the systems show ferromagnetism with Mn and N doping, whereas no magnetization was found with La doping in G- and C-type antiferromagnetic orderings. Our research further revealed that the ferromagnetism is attributed to the p-d orbital hybridization. Berry-phase polarization calculations predicted a large polarization of 149.2 µC/cm2 along the [001] direction of pure tetragonal BFO. We found that La and N substitution had little influence on the spontaneous polarization, whereas Mn substitution reduced the spontaneous polarization. The reduced energy barrier heights of the doped systems indicate the reduced stability of the off-centering ferroelectricity against the thermal agitation. These findings provide greater understanding for controlling and tuning the multiferroic properties of BFO.
Wheat Straw-Derived N-, O-, and S-Tri-doped Porous Carbon with Ultrahigh Specific Surface Area for Lithium-Sulfur Batteries
Authors: Chen Feng , Ma Lulu , Ren Jiangang , Zhang Mou , Luo Xinyu , Li Bing , Song Zhiming , Zhou Xiangyang
Published: June 2018

Recently, lithium-sulfur (Li-S) batteries have been greeted by a huge ovation owing to their very high theoretical specific capacity (1675 mAh·g−1) and theoretical energy density (2600 Wh·kg−1). However, the full commercialization of Li-S batteries is still hindered by dramatic capacity fading resulting from the notorious “shuttle effect” of polysulfides. Herein, we first describe the development of a facile, inexpensive, and high-producing strategy for the fabrication of N-, O-, and S-tri-doped porous carbon (NOSPC) via pyrolysis of natural wheat straw, followed by KOH activation. The as-obtained NOSPC shows characteristic features of a highly porous carbon frame, ultrahigh specific surface area (3101.8 m2·g−1), large pore volume (1.92 cm3·g−1), good electrical conductivity, and in situ nitrogen (1.36 at %), oxygen (7.43 at %), and sulfur (0.7 at %) tri-doping. The NOSPC is afterwards selected to fabricate the NOSPC-sulfur (NOSPC/S) composite for the Li-S batteries cathode material. The as-prepared NOSPC/S cathode delivers a large initial discharge capacity (1049.2 mAh·g−1 at 0.2 C), good cycling stability (retains a reversible capacity of 454.7 mAh·g−1 over 500 cycles at 1 C with a low capacity decay of 0.088% per cycle), and superior rate performance (619.2 mAh·g−1 at 2 C). The excellent electrochemical performance is mainly attributed to the synergistic effects of structural restriction and multidimensional chemical adsorptions for cooperatively repressing the polysulfides shuttle.
Severe early childhood caries and behavioral risk factors among 3-year-old children in Lithuania
Authors: Slabšinskienė Eglė , Milčiuvienė Simona , Narbutaitė Julija , Vasiliauskienė Ingrida , Andruškevičienė Vilija , Bendoraitienė Eglė-Aida , Saldūnaitė Kristina
Published: June 2018

The objective of the present study was to investigate the prevalence and severity of early childhood caries (ECC) and severe early childhood caries (S-ECC) in 3-year-old Lithuanian children. The impact of selected behavioral risk factors on the development of S-ECC was investigated. Material and methods. A total of 950 children were examined in kindergartens. Diagnosis of dental caries followed the WHO criteria. Questionnaires were delivered to mothers of the children with S-ECC and caries-free children. The questions were related to the children’s dietary habits, temperament, oral hygiene, and the use of fluoride toothpaste. Results. The prevalence of ECC was 50.6% with a mean dmft of 2.1 (SD, 0.1) and a mean dmfs of 3.4 (SD, 0.2). The prevalence of S-ECC was 6.5% with a mean dmft of 7.8 (SD, 0.1) and dmfs of 18.1 (SD, 0.6). A significantly higher percentage of children developed S-ECC when they were breast-fed for a period longer than one year, were sleeping with a bottle containing carbohydrates during the night, or were allowed to sip from a bottle either going to sleep or during the day. A significantly higher percentage of mothers having caries-free children knew about risk factors of S-ECC and started tooth brushing after the eruption of the first tooth. There was no significant difference between the groups regarding the use of fluoride toothpaste. Conclusions. Improper infant bottle-feeding habits and no tooth brushing were found to be significant for the development of S-ECC among 3-year-old Lithuanian children.
Vehicle-associated closed trauma-induced stroke in a 27-day-old girl
Authors: Talvik Inga , Peet Aleksandr , Laugesaar Rael , Lintrop Mare , Talvik Tiina
Published: June 2018

Birth trauma, but not postnatal trauma, has been recognized as a cause of cerebral infarction in newborns. We report a case of cerebral infarction in a 27-day-old girl after a car accident. During the car accident, the child was properly restrained to the child’s safety seat. The patient was admitted to the hospital for observation because of pronounced irritability. There were no focal neurological symptoms on admission. Twenty-eight hours after the accident, the child developed focal tonic-clonic seizures and mild right-sided hemiparesis. The seizures were successfully treated with phenobarbital at a dose of 30 mg per day. Computed tomography and magnetic resonance imagining performed on the second and third days after the accident, respectively, showed subdural hemorrhage in the occipital regions and cerebral ischemia in the left parieto-occipital region. Control imaging 10 days later showed signs of reperfusion. Persistent child irritability after head trauma is one of the indicating factors for performing an emergency computed tomography scan of the head.
Associations between depressiveness and psychosocial factors in Lithuanian rural population
Authors: Šidlauskaitė-Stripeikienė Ieva , Žemaitienė Nida , Klumbienė Jūratė
Published: June 2018

Background and objective. Data from various scientific studies all over the world show that depression is becoming one of the biggest health problems in society. The aim of this study was to evaluate characteristics of depressiveness and its associations with psychosocial factors (stress, social support, suicidal intentions) in Lithuanian adult rural population. Material and methods. Within the Countrywide Integrated Non-communicable Diseases Intervention (CINDI) program, the survey was carried out in a stratified random sample of population aged 25–64 in 5 rural regions of Lithuania between 2006 and 2007. A total of 1754 participants were examined. Results. About half (43.8%) of respondents experienced high and moderate levels of depressiveness. Women in comparison to men reported higher levels of depressiveness. The likelihood of depressiveness among women was related to older age, lower education, small social network, lower level of social support, higher level of stress, and suicidal intentions. Whereas, the same indicator among men was associated with older age, lower education, being divorced, small social network, having no social support, higher level of stress, and suicidal intentions. Conclusions. Depressiveness is highly prevalent among Lithuanian rural population with a higher prevalence among women than men. Older persons and persons with lower education of both genders were more likely to be depressed than younger and more educated persons. Absence of social support, high level of stress, and suicidal intentions were related to higher levels of depressiveness in both genders. Depressiveness was more common among women having a small social network and divorced men.
“Modified” Liquid–Liquid Displacement Porometry and Its Applications in Pd-Based Composite Membranes
Authors: Zheng Lei , Li Hui , Yu Haijun , Kang Guodong , Xu Tianying , Yu Jiafeng , Li Xinzhong , Xu Hengyong
Published: June 2018

For H2 separation by Pd-based composite membranes, the pore mouth size distribution of the porous support immediately affects the quality of the deposited layer, including continuity and defect/pinhole formation. However, there is a lack of convenient and effective methods for characterization of pore mouth size of porous supports as well as of defect distribution of dense Pd-based composite membranes. Here we introduce a novel method by modifying conventional liquid–liquid displacement porometry. When the pore tunnels are filled with Liquid B and the outer surface is occupied by Liquid A, the reopening of the pore mouth depends on the pressure of Liquid B and the interfacial tension at the position of the pore mouth, from which the pore mouth size can be determined according to the Young–Laplace equation. Our experimental tests using this method with model samples show promising results, which are well supported by those obtained using FESEM (fild emission scanning electron microscope), AFM (atomic force microscope), and conventional liquid–liquid displacement porometry. This novel method can provide useful information for not only surface coatings on porous substrates but also for modification of dense membrane defects; thus, broad utilizations of this technique can be expected in future study.
Synthesis of Complex-Alloyed Nickel Aluminides from Oxide Compounds by Aluminothermic Method
Authors: Gostishchev Victor , Ri Ernst , Ri Hosen , Kim Evgeniy , Ermakov Michail , Khimukhin Sergey , Deev Vladislav , Prusov Evgeny
Published: June 2018

This paper deals with the investigation of complex-alloyed nickel aluminides obtained from oxide compounds by aluminothermic reduction. The aim of the work was to study and develop the physicochemical basis for obtaining complex-alloyed nickel aluminides and their application for enhancing the properties of coatings made by electrospark deposition (ESD) on steel castings, as well as their use as grain refiners for tin bronze. The peculiarities of microstructure formation of master alloys based on the Al–TM (transition metal) system were studied using optical, electronic scanning microscopy and X-ray spectral microanalysis. There were regularities found in the formation of structural components of aluminum alloys (Ni–Al, Ni-Al-Cr, Ni-Al-Mo, Ni-Al-W, Ni-Al-Ti, Ni-Cr-Mo-W, Ni-Al-Cr-Mo-W-Ti, Ni-Al-Cr-V, Ni-Al-Cr-V-Mo) and changes in their microhardness, depending on the composition of the charge, which consisted of oxide compounds, and on the amount of reducing agent (aluminum powder). It is shown that all the alloys obtained are formed on the basis of the β phase (solid solution of alloying elements in nickel aluminide) and quasi-eutectic, consisting of the β′ phase and intermetallics of the alloying elements. The most effective alloys, in terms of increasing microhardness, were Al-Ni-Cr-Mo-W (7007 MPa) and Al-Ni-Cr-V-Mo (7914 MPa). The perspective is shown for applying the synthesized intermetallic master alloys as anode materials for producing coatings by electrospark deposition on steel of C1030 grade. The obtained coatings increase the heat resistance of steel samples by 7.5 times, while the coating from NiAl-Cr-Mo-W alloy remains practically nonoxidized under the selected test conditions. The use of NiAl intermetallics as a modifying additive (0.15 wt. %) in tin bronze allows increasing the microhardness of the α-solid solution by 1.9 times and the microhardness of the eutectic (α + β phase) by 2.7 times.
Evolution of the Microstructure and Lamellar Orientation of a β-Solidifying γ-TiAl-Based Alloy during Hot Compression
Authors: Zhu Kai , Qu Shoujiang , Feng Aihan , Sun Jingli , Shen Jun
Published: June 2018

A type of advanced γ-TiAl-based alloy called β-solidifying γ-TiAl has elicited remarkable research interest in the last few decadesbecause of its excellent workability and homogeneous microstructures. Thermomechanical treatments are widely applied to this alloy to obtain fine duplex microstructures. To investigate the deformation behavior and microstructure evolution of Ti-44Al-4Nb-1.5Cr-0.5Mo-0.2B alloy, we conducted a series of hot compression tests at a temperature of 1473 K and a strain rate of 0.01 s−1. Scanning electron microscopy, electron backscattered diffraction, and transmission electron microscopy were performed to analyze the crystal orientation and microstructures of the alloy. During compression at 1473 K, β/B2→γ transition and α2/γ lamellae→γ+β/B2 transition occurred simultaneously, which increased the content of the γ phase and decreased the content of the α2 phase. The lamellar colonies exhibited distinct anisotropy, which could affect their hot deformation behavior. The colonies that remained after compression had strong texture components.
Correlation between the Potency of Flavonoids on Mushroom Tyrosinase Inhibitory Activity and Melanin Synthesis in Melanocytes
Authors: Promden Worrawat , Viriyabancha Wittawat , Monthakantirat Orawan , Umehara Kaoru , Noguchi Hiroshi , De-Eknamkul Wanchai
Published: June 2018

Twenty-seven flavonoids isolated from Dalbergia parviflora with vast structural diversity were screened for inhibitory activity against mushroom and murine tyrosinases using l-DOPA as the substrate. Among the flavonoids tested, only four—khrinone (5), cajanin (9), (3RS)-3′-hydroxy-8-methoxy vestitol (21), and (6aR,11aR)-3,8-dihydroxy-9-methoxy pterocarpan (27)—reacted with mushroom tyrosinase, with IC50 values of 54.0, 67.9, 67.8, and 16.7 μM, respectively, and only compound 27 showed inhibitory activity against murine tyrosinase. With cell-based assays, only compounds 9 and 27 effectively inhibited melanogenesis in B16-F10 melanoma cells (by 34% and 59%, respectively), at a concentration of 15 μM, without being significantly toxic to the cells. However, the crude extract of D. parviflora and some of the flavonoid constituents appeared to increase melanin production in B16-F10 cells, suggesting that there are flavonoids with both inhibitory and stimulatory melanogenesis in the crude extract. Studies on the correlation between the enzyme-based and cell-based assays showed that only the flavonoids with IC50 values below 50 μM against mushroom tyrosinase could inhibit the mammalian tyrosinase, and thus, reduce melanogenesis in B16-F10. Flavonoids with the IC50 values greater than 50 μM, on the other hand, could not inhibit the mammalian tyrosinase, and had either no effect or enhancement of melanogenesis. In conclusion, the tyrosinase enzyme from mushroom is not as selective as the one from mammalian source for the enzyme-based melanogenesis inhibitory screening, and the mammalian cell-based assay appears to be a more reliable model for screening than the enzyme-based one.