bluuebunny/crossref_metadata_2025 huggingface dataset:
Opportunities and Challenges in Implementing Distance Learning and e-Learning
Authors: Sesabo Jennifer Kasanda , Mfaume Rashid , Msabila Dominik T.
Published: May 2015

In Tanzania, the growing demand for education due to massive enrolment in universities calls for adoption of Distance Learning (DL) and e-learning. Other factors for adoption include limited space and pace of learning, pedagogical weaknesses, and shortage of teaching staff. Mzumbe University also experiences the same as it operates satellite teaching centres of Morogoro town, Mbeya, Dar es Salaam, Tanga and Mwanza. This has made the university consider shifting from conventional delivery modes to alternative pedagogical strategies using Information and Communications Technology (ICT). The aim is to ensure effective delivery of quality education. There are opportunities and challenges. The challenges include absence of national and institutional quality assurance system framework on e-learning and distance education, and shortage of teaching staff and ICT facilities. Thus, universities need appropriate budget and resource investment to support capacity building for teaching staff and students, and formulating policies, guidelines and operational framework on distance learning and e-learning.
Active Learning with Technology Tools in the Blended/Hybrid Classes
Authors: Murungi Catherine Gakii , Gitonga Rhoda K.
Published: May 2015

Blended/hybrid classrooms technological tools and resources in this paper refers to: Personal and public computers, Projectors (LCD), E-learning management system, E-journals, Interactive CD or DVD, Video cameras, search engines and video conferencing. Universities in Kenya are buying computers, for departments, lecturers' offices and equipping computer labs for the students while increasing bandwidth and internet connectivity. But is the investment in technology translating to faculty and student use in blended classrooms? This chapter seeks to find out the answer to this critical question. A sample of 231 students and 219 lecturers from universities within Nairobi metropolitan was selected. Data was analyzed using descriptive statistics. The findings reveal that the universities made available blended/hybrid education and its technological tools and resources to students and lecturers for interaction in the teaching/learning process but they were less aware of the online technical resources and tools that can be used in the blended classrooms.
Appraisal Theory
Authors: Rambe Patient
Published: May 2015

While Writing Centres provide dialogic spaces for student articulation of voice, they insufficiently deal with asymmetrical power relations built into expert-novice conversations, which potentially disrupt novices' democratic expression of their voices. Yet the conversational nature of Facebook presents opportunities for ESL students to express their voices. This chapter: 1) Employs draft essays of first-year ESL students submitted to a Writing Centre to unravel their challenges with asserting their voice, 2) Uses reflective narratives of Writing consultants and ESL students to understand how their English language acquisition is impacted by their appropriation of Facebook and 3) Unravels how Facebook complements the mandate of Writing Centres of developing the academic voice of students. Findings suggest that students lacked confidence in asserting their authorial presence and familiarisation with academic conventions. Students and consultants' essays demonstrated a balanced appropriation of attitudinal and judgement categories and engagement resources, with implications for the potential of Facebook to mediate student expression of their voice.
Estimation for the Si-O Structures Based on the Homology Concept
Authors: Nakane Kazuaki , Halasz Istvan
Published: May 2015

The first atomically resolved transmission electron microscopic (TEM) pictures of silica gels showed visible differences between their molecular densities (MD), which might be the molecular foundation of their distinctly different macroscopic properties, like porosity, surface area, fragility, etc. [1, 2]. Thus, learning to control MD promises the first time to add rational chemical design to the largely empirical synthesis methods of silica gels with desirable physical properties. However there is no known method for the quantitative comparison of molecular densities of these amorphous materials. We report in this paper a new numerical image-analyzing method, utilizing the mathematical theory of homology [3], which allows to measure quantitatively the molecular density of silica gels from their high resolution TEM pictures.
Relationship between Solid Lubricant Layer and Friction Coefficient of PPS Races-PTFE Retainer Hybrid Thrust Bearings under Dry Condition
Authors: Shi Xiao Chen , Mizobe Koshiro , Kashima Yuji , Kida Katsuyuki
Published: May 2015

Due to the advantage on low coefficient and self-lubricant, PPS races-PTFE retainer hybrid polymer bearings can offer better service performance under certain condition. In our previous study, the relationship between friction coefficient and rotation speed was investigated, and formation of black layer was found. In the present study, EPMA was introduced to investigate the component and thickness of the black layers. Based on the observations, the relationship between friction coefficient, solid lubricant layer and thrust load was also discussed.
The Analysis of the Effect of Surface Stresses at Nanoscale
Authors: Ou Zhi Ying , Wu Ya Wen
Published: May 2015

Based on classical elasticity theory, the effects of surface stresses on the nanosized contact problem in an elastic half-plane which contains a nanocylindrical hole are analyzed. Meanwhile, the effects of surface energy of the contact nanosized surface are considered. The complex variable function method is applied to derive the fundamental solution of the contact problem. As example, the deformation induced by a distributed traction of cosine function on the nanosized surface is analyzed in detail. The results tell some interesting characteristics in contact mechanics, which are different from those in classical elasticity theory.
Experimental Study of the Deformation Behaviour and Mechanical Properties of Fresh Reinforced Bamboo
Authors: Gyansah Lawrence , Abd El-Aty A.M.
Published: May 2015

A
bstract. This paper investigates the deformation behavior of reinforced fresh bamboo subjected to static-compressive loading condition. Crushing strength test was performed using Uniaxial Compression Machine with maximum loading capacity of 1500 kN. The data is plotted as strength to weight ratio versus height, strength to volume ratio versus height, failure stress versus height, load versus time of failure and load to height ratio versus time of failure. Result shows that increase in height of the fresh reinforced bamboo increases the strength and vice versa. The moisture content also has significant influence on the strength of the fresh reinforced bamboo. The moisture content reduced the strength of the fresh reinforced bamboo by 21.8 %. This percentage is really significant in structural analysis since it can cause catastrophic failure to structures. Concrete is significant in reinforcing bamboo structures for a better strength. The crushing stresses for fresh reinforced bamboo of heights 250 , 210 ,170 , 130 and 90 mm were found to be 26.09 , 25.52 , 24.85 , 21.97 , 21.86 MPa respectively. The failure stress of the bamboo is about say 1.26 M times the weight of the bamboo per square meter. The specific compressive strength which explains the bending moment per kilogram of the bamboo specimen also increases with increases in height. Failure stress to weight ratio decreases with increases with the height of the bamboo. Strength to volume ratio also decreases with increases with the height from the bamboo.
Emission Factors for Dioxin for Coal Burning, Secondary Smelting and Alloying of Aluminum, and Cement Kiln Processes
Authors: Cheng Yu Yen , Lu Mei Fang , Lin Jim Jui Min
Published: May 2015

While conducting research for dioxin emission factor for stationary source emission, it is found that some factors come from overestimation. The cause of discrepancy for estimating process comes often from lacking understanding of the process. The result of this study for secondary aluminum refining emission factors indicates that if raw materials are scraps, the factors averaged at 541 ng I-TEQ/Ton-raw materials. If waste aluminum is used as the raw material, factors averaged at 1338 ng I-TEQ/Ton-raw material. The factors based on site sampling for coal-fired power generation process is 24.84-549.62 ng I-TEQ/Ton-fuel. It varies according to coal sources. Emission factor for cement producing process is 95.4-102.66 ng I-TEQ/Ton-raw material. Due to fewer differences in operating traits, raw materials and fuel application for cement producing process, emission factors have smaller differences. The reliability for emission variables is relatively higher.
Patch Designing for Damaged Metallic Structure Repaired with Adhesively Bonded Composite Patch
Authors: Zhang Ding , Ding Wen Yong , Su Feng , Jin Shi Jiao
Published: May 2015

Composite patch adhesively bonded repair is an advanced repairing method for damaged metallic structure, and patch designing is important before repairing, which decides final repairing effect. Based on 3D FEM, the model of aluminum plate with a central through crack adhesively bonded repaired with composite patch was established, which can take into account residual thermal stress and bending deformation caused by differences of thermal expansion coefficient. SIF was calculated using virtual crack closure technology and compared to evaluate patch designing. The results show that for through centrally cracked aluminum plate, rectangle boron/epoxy patch is the best, and more plies whose fiber direction is parallel to loading direction are, better repairing can be got.
Effect of Heat Treatment on the Mechanical Properties and Interface Structure of 3-ply Ti/Cu/Ti Clad Composite
Authors: Kim Yong Keun , Shin Pyung Woo , Hong Sun Ig
Published: May 2015

The effect of heat treatment on the mechanical properties and interface structure of 3-ply Ti/Cu/Ti clad composite was investigated. Strength decreased and the ductility increased with increase of heat treatment temperature. The gradual increase of hardness at 700°C and 800°C indicates the growth of intermetallic compounds at the interface. No visible intermetallic compound formation was observed up to 400°C. The intermetallic layer grew very rapidly above 600°C and its thickness reached ~10μm after heat treatment at 800°C. The absence of cracks emanating from the corners of the indentation mark indicates that intermetallics in Ti/Cu/Ti clad are ductile enough to accommodate the micro-plastic flow from indentation. Four intermetallic layers at the interface were confirmed to be Cu4Ti, Cu3Ti2, CuTi and CuTi2 based on the EDS spectra, XRD and phase diagram analyses.
Relation between the Betti Number of Fatigue Fracture Surfaces and Stress Intensity Factors of Low Carbon Steel (JIS, S45C)
Authors: Ishida Masayuki , Kida Katsuyuki , Mizobe Koshiro , Nakane Kazuaki
Published: May 2015

The study of fracture surfaces of materials is very important to understand failures in engineering elements, especially in structural products. However, it is not easy to evaluate fatigue fracture surfaces by using ordinary image analysis techniques. In this paper, we propose a new analyzing method to evaluate fatigue fracture surfaces from a view point of Homology.
High Thermal Stability of Mo/Si3N4/Mo/Si3N4/SiO2 Multilayer Solar Selective Coatings
Authors: Yang Rui Hua , Liu Jin Yang , Lin Li Mei , Lai Fa Chun , Qu Yan , Zheng Wei Feng
Published: May 2015

In terms of good optical properties and high thermal stability, Mo/Si3N4/Mo/Si3N4/SiO2 coatings based on metal/dielectric multilayer structure were adapted to the solar selective coating at high operating temperatures. The coatings exhibited high solar absorptance in the range of 0.924 ~ 0.936 and low thermal emittance of 0.114 ~ 0.118. The coatings deposited on quartz substrates were thermally stable up to 625 °C in air for 2 h, while they were degraded at 650 °C from the characterization of the absorptance and emittance. The degradation of the coatings was mainly due to the oxidation of molybdenum in air, which was confirmed by Raman spectroscopy. Compared with the thermal stability in air, the coatings were much more stable in vacuum under high temperature. The remarkable thermal stability of the Mo/Si3N4/Mo/Si3N4/SiO2 coatings in air and in vacuum makes them suitable to be applied at high temperature applications.
Validation of a Novel Approach for CO2/N2 Gas Separations by Means of a Hybrid Ceramic Membrane
Authors: Nwogu Ngozi Claribelle , Kajama Mohammed Nasir , Gobina Edward
Published: May 2015

Global warming has been documented as one of the world’s foremost ecological concerns. Although it is difficult to totally end human related global warming, there is a possibility to alleviate these effects through a wide spectrum of options. One such possibility is the reduction of atmospheric carbon dioxide emissions, a major greenhouse gas widely thought to be responsible for global warming. This paper therefore looks at an experimental validation of gas separation by means of a high selective membrane for CO2 recovery applications. Analysis of the results obtained is in good agreement with literature experimental data. Additional results show that CO2 selectivity factor is reasonable for capture of CO2 from N2 as a key constituent in a flue gas stream.
Baddeleyite Type Monoclinic Zirconium Oxide Nanocrystals Formation
Authors: Yuvakkumar R. , Hong Sun Ig
Published: May 2015

We report successful synthesis of baddeleyite type monoclinic zirconium oxide nanocrystals formation. The product mixture of zirconium incubated at room temperature for 7 days were thoroughly investigated employing X-ray diffraction, Raman spectroscopy and transmission electron microscopy studies. XRD and Raman studies revealed the formation of baddeleyite type monoclinic zirconium oxide nanocrystals. TEM studies revealed the nanocrystal formation with size ranging from 100 nm to 200 nm.
Hydrogen Separation Using Inorganic Membranes
Authors: Kajama Mohammed Nasir , Nwogu Ngozi Claribelle , Gobina Edward
Published: May 2015

Gas permeation of hydrogen (H2) and nitrogen (N2) were obtained from 30 and 6000 nm pore diameter tubular commercial alumina ceramic membranes at 0.05 to 1.00 bar and 298 K. Flow rates of up to 3.279 and 2.296 l/min were obtained for H2and N2respectively. The ratio of H2/N2flow rates were used to calculate H2/N2selectivity. The experimental H2/N2selectivities obtained were 1.85 and 1.43 for the 30 and 6000 nm respectively.
Magnesium Phosphate/Polybutylene Succinate Composite for Bone Repair
Authors: Wang Quan Xiang , Dong Xie Ping , Tang Xiao Feng , Wu Ying Yang , Ding Yue Ting , Yu Bao Qing , Chen Jie , Wei Jie
Published: May 2015

MP/PBS composite was fabricated by melt blending method. The weight loss ratio of MP/PBS composite reached 35.43 wt.% after immersion into phosphate buffered saline solution for 12 weeks, and the pH change from 7.40 to 7.72. The relative proliferation rate of cells on the materials increased with time and the proliferation of the cells on the MP/PBS composite was significantly higher than PBS. The results reveal MP/PBS composite has good biocompatibility, which satisfied the relevant criterion on biomaterials.
Characterisation of Inorganic Composite Ceramic Membrane for Lactic Acid Esterification Processes
Authors: Okon Edidiong , Shehu Habiba , Gobina Edward
Published: May 2015

The use of inorganic composite membranes in chemical industries has received a lot of attention more recently due to a number of exceptional advantages including thermal stability and robustness. Inorganic membranes can selectively remove water from the reaction mixture during esterification reactions in order to enhance product formation. The characterisation of inorganic composite membranes used in this work including the determination of the pore diameter and specific surface area was performed using Liquid Nitrogen adsorption at 77 K. The membrane was modified once. The permeation test for the single gases including carbon dioxide (CO2), helium (He), nitrogen (N2) and argon (Ar) through the inorganic composite ceramic membrane was carried out at the gauge pressure range of 0.10 – 1.00 bar and at the temperature of 393 K. The order of the gas molecular weight was He < N2 < CO2 < Ar. The BET surface area of the dip-coated silica membrane showed a type IV isotherm characteristic of mesoporous structure with hysteresis. The BJH curve of the silica-membrane was in accordance with mesoporous classification.
Theoretical Evaluation of Anisotropic Distortion Associated with Point Defects in Ordered Compounds
Authors: Souissi Maaouia , Nakamura Ryusuke , Numakura Hiroshi
Published: May 2015

To verify the assumption that the anelastic relaxation effect observed in Ni3Al is due to stress-induced reorientation of antisite Al atoms [Numakura and Nishi, Mater. Sci. Eng. A 442 (2006) 59-62], the magnitudes of the anisotropic distortion produced by the intrinsic point defects have been evaluated by ab initio calculations. The anisotropy of the λ tensor (the strain per unit concentration of a particular defect) for the two candidate defect species, namely a Ni vacancy and an antisite Al atom, has been computed by full structure optimization of a supercell containing a single point defect: the difference in the principal values is +0.46 and −1.12, respectively. The relaxation strength estimated for antisite Al atoms agrees fairly well with experiment, while that for Ni vacancies is far too small because of their much lower concentration. The relaxation is, therefore, conclusively attributed to antisite Al atoms.
Effect of Purity on Dislocation-Induced Relaxations in Molybdenum Single Crystals
Authors: Suzuki Shigeru , Seeger Alfred
Published: May 2015

Dislocation-induced relaxations in different molybdenum single crystals were investigated by means of low-frequency internal friction measurements in the temperature range of 20–600 K. The results indicated that the appearance of the dislocation-induced relaxations strongly depends on the purity of the molybdenum, although the intrinsic dislocation relaxations appeared at about 100 K and 450 K in the high-purity molybdenum. The molybdenum containing a small amount of carbon did not exhibit the intrinsic dislocation relaxations but rather revealed a modulus increase due to the dislocation pinning caused by the dissolved carbon. When the molybdenum containing a small amount of carbon was annealed up to 700 K, a new relaxation peak appeared at about 450 K. The activation process for this relaxation indicated that it could be attributed to the relaxation due to a carbon-dislocation interaction. In addition, it was shown that the dislocation-induced relaxations in medium-purity molybdenum were small, which was attributed to the residual substitutional impurities in the molybdenum.
The Model of the Layer Boundary Diffusion in Multilayer Materials
Authors: Petelin Alexander , Plokhikh Andrey , Novikov Alexander , Novikova Elena
Published: May 2015

The results of metallographic studies show the effect of the layers thickness of multilayer metal material on the diffusion depth after chemical heat treatment. The accelerate diffusion model of diffusible element along layers boundaries is proposed.
Crystallization and Reconstructive Layer Transformation of a-Si/Au Multilayer Thin Films under a Strong Gravitational Field
Authors: Okamoto Yoichi , Aono Masami , Miyazaki Hisashi , Ogata Yudai , Tokuda Makoto , Mashimo Tamotsu
Published: May 2015

There were still unclear questions in the new method that fabricate the high quality poly crystalline Si thin film from amorphous Si thin film with lower annealing temperature than conventional Si recrystallization temperature. In that recrystallization process, the recrystallization mechanism was generally explained by the MIC (Metal Induced Crystallization) of Au. In this paper, we have discussed the effects of film structure and strong gravity on recrystallization, by using conventional furnace and high-temperature ultracentrifuge furnace system. The five kinds of samples (two bilayered Si/Au thin films, two multilayered Si/Au thin films and trilayered Si/Au/Si thin film) and found the effects of structure and strong gravity. The best for crystallization was Au/Si multilayered thin film, which is almost finished to crystallize even at 673 K annealing. The strong gravity advanced and retreated the crystallization, depending to thin film structure.
Modeling the Nitrogen Diffusion Enhancement Resulting from a NanoPeening® Treatment on a Pure Iron – Influence of the Grain Morphology
Authors: Lacaille Victor , Kermouche Guillaume , Tumbajoy-Spinel David Yezid , Feulvarch Eric , Morel Constance , Bergheau Jean Michel
Published: May 2015

It is well known that nanocrystalline materials have enhanced diffusion properties due to their high grain boundary density which act as fast diffusion channels compared to the lattice. In this paper, we aim at simulating the nitriding process of a pure iron nanostructured by NanoPeening® process. We use a simple diffusional approach taking into account the grain size and the grain morphology resulting from the NanoPeening® treatment. EBSD measurements are carried out to extract morphological parameters which are used in the homogenization method to extract the effective diffusivity distribution. Then a 1D diffusion simulation is performed with this distribution and shows that the grain morphology resulting from the NanoPeening® treatment does not deteriorate the diffusion properties of the material but in fact, improves the nitrogen penetration depth and the diffusion kinetics in addition to the effect of the grain size reduction.
Magneto-Plastic Effect in Cu-Be Alloys with Ni Additives
Authors: Osinskaya J.V. , Pokoev A.V.
Published: May 2015

The paper presents a brief review of experimental results obtained in the study on the effect exerted by Ni-additives (0.4 and 1.0 wt. %) on the kinetic processes occurring during the artificial aging of copper-beryllium alloys under a constant magnetic field. Probable atomic mechanisms of the effects observed are also discussed.
A SIMS Study on Self-Diffusion in Thin Nano-Crystalline Platinum Films
Authors: Gruber Wolfgang , Strauß Florian , Schmidt Harald
Published: May 2015

Self-diffusion in thin nanocrystalline Pt films was investigated using secondary ion mass spectrometry. Our experiments are motivated by recent investigations on stress relaxation where self-diffusion of Pt is supposed to play an important role, especially at temperatures below 250 °C and annealing times of a few hours. For the diffusion experiments, double layers of natPt/194Pt were deposited on oxidized silicon wafers using ion beam sputtering. At 180 °C no significant diffusion induced broadening of the profiles could be observed even after an annealing time of 64 h. However, the concentration of 195Pt in the top layer decreases slightly after an annealing time of 16 h and remains constant for higher annealing times. At 600 °C a broadening of the profiles was observed after an annealing time of 5 minutes. From our results we conclude that at 180 °C only atoms in the grain boundaries are mobile. After about 16 h the isotopes in the grain boundaries are completely interdiffused. From the change of the 195Pt concentration in the top layer we estimate the amount of grain boundary phase in the Pt films to be about 5 %. The broadening of the profile after annealing at 600 °C is attributed to bulk diffusion.
Interdiffusion: Consistency of Darken's and Onsager's Methods
Authors: Dąbrowa J. , Kucza Witold , Tkacz-Śmiech Katarzyna , Bożek Bogusław , Danielewski Marek
Published: May 2015

The Nernst-Planck flux formula is used in Darken's method to obtain the interdiffusion fluxes. The effective interdiffusion potentials, derived for the independent components in the system, allow obtaining the symmetrical matrix of the interdiffusion coefficients. The transport coefficients for 2, 3 and r-component system are presented. Interpretation of obtained matrixes in the light of Onsager's theory of irreversible thermodynamics is shown. Equation for the entropy production in the interdiffusion process is displayed. The presented approach allows calculation of entropy production during interdiffusion, as well as formulating Onsager's phenomenological coefficients for the interdiffusion in an explicit form, a form which is directly correlated with the mobilities of the atoms present in the system.
Fabrication of Copper Nanowire Arrays by Electrolytic Deposition
Authors: Chen Cai Feng , Wang Hao , Ding Zhi Dan , Wang An Dong
Published: May 2015

Highly ordered copper nanowire arrays were prepared by electrolytic deposition using porous anodic aluminum oxide (AAO) as template. The technique of removing the barrier layer of the AAO template by the pore widening procedure was investigated. The quality of the Au conducting layers sputtered at the bottom side of the AAO template was also studied. The direct current (DC) electrodeposition of copper nanowire arrays was performed efficiently above the Au layer inside the pores. The morphology of the copper nanowires was characterized by scanning electronic microscopy (SEM) and the composition of Cu nanowires was confirmed by energy dispersive X-Ray spectroscopy (EDS). The results showed that the best condition was found to be in phosphoric acid (6%wt) for 10 min to remove the barrier layer completely. Au layer was uniform and dense after sputtering for four times. Copper nanowire arrays were successfully prepared by three-electrode and two-electrode cell electro-deposition, but the nanowire arrays were more ordered by using three-electrode cell and the length of nanowires was more uniform. The diameter of a single Cu nanowire is less than 100 nm with the length up to around 10 μm, and the nanowires are well arranged in arrays.
Comparative Studies in Dispersing Nanoparticles in a Styrene Butadiene Rubber Matrix via Different Blending Methods
Authors: Vasudeo Rane Ajay , Abitha V.K. , Suchithra P.S. , Rajkumar K.
Published: May 2015

InIncorporation and dispersion of particulate fillers are the two steps that are necessary to achieve optimum properties in a rubber compound, i.e. mechanical, thermal properties. The incorporation and dispersion of particulate fillers depend on their particle size, smaller particle size is difficult to incorporate but easier to disperse in a rubber matrix while large dimension particle size filler are easier to incorporate but difficult to disperse. Hence, in the current work we have studied different methods of incorporating nano particles in to the matrix of styrene butadiene rubber and further rubber nanocomposites obtained were characterized for curative properties using, remote, thereafter determined for structural elucidation by using Fourier transform infrared spectroscopy, thermal properties through thermal gravimetric analysis, Physio-mechanical as well as morphology determination via transmission electron microscopy. In current work we have compared melt blending and solution blending methods for preparation of styrene butadiene rubber Nano Aluminium Tri hydroxide composites.
Characterization of Serum Cytokine Profile in Predominantly Colonic Inflammatory Bowel Disease to Delineate Ulcerative and Crohn's Colitides
Authors: Korolkova Olga Y. , Myers Jeremy N. , Pellom Samuel T. , Wang Li , M'koma Amosy E.
Published: May 2015

Background

As accessible diagnostic approaches fail to differentiate between ulcerative colitis (UC) and Crohn's colitis (CC) in one-third of patients with predominantly colonic inflammatory bowel disease (IBD), leading to inappropriate therapy, we aim to investigate the serum cytokine levels in these patients in search of molecular biometric markers delineating UC from CC.

Methods

We measured 38 cytokines, chemokines, and growth factors using magnetic-bead-based multiplex immunoassay in 25 UC patients, 28 CC patients, and 30 controls. Our results are compared with those from a review of current literature regarding advances in serum cytokine profiles and associated challenges preventing their use for diagnostic/prognostic purposes.

Results

Univariate analysis showed statistically significant increases of eotaxin, GRO, and TNF-α in UC patients compared to controls (Ctrl); interferon γ, interleukin (IL)-6, and IL-7 in CC group compared to Ctrl; and IL-8 in both UC and CC versus Ctrl. No cytokines were found to be different between UC and CC. A generalized linear model identified combinations of cytokines, allowing the identification of UC and CC patients, with area under the curve (AUC) = 0.936, as determined with receiver operating characteristic (ROC) analysis.

Conclusions

The current knowledge available about circulating cytokines in IBD is often contradictory. The development of an evidence-based tool using cytokines for diagnostic accuracy is still preliminary.
Скорость наилучшего приближения констант наипростейшими дробями и альтернанс
Authors: Komarov Mikhail Anatol'evich
Published: May 2015

Рассматривается задача интерполяции и
наилучшего равномерного приближения констант $c\ne 0$
наипростейшими дробями $\rho_n$ порядка $n$ на отрезке $[a,b]$
(все величины вещественны). В случае $n>4|c|(b-a)$
доказана однозначная разрешимость задачи интерполяции,
получены точные по порядку $n$ верхняя и нижняя оценки
погрешности интерполяции в совокупности всех узлов и показано,
что полюсы интерполяционной дроби лежат вне круга
с диаметром $[a,b]$. Получен один из аналогов
классической теоремы Чебышeва о наименьшем уклонении
унитарного полинома степени $n$ от константы. А именно,
при $n>4|c|(b-a)$ доказано, что дробь $\rho_n^*$
наилучшего приближения константы $c$ на $[a,b]$ единственна
и характеризуется чебышевским альтернансом из $n+1$ точки
для разности $\rho_n^*-c$. Получена точная по порядку $n$
оценка наименьших уклонений.
Библиография: 16 названий.
Нелинейные уравнения типа свертки в пространствах Лебега
Authors: Askhabov Sultan Nazhmudinovich
Published: May 2015

Методами теории монотонных операторов доказаны глобальные
теоремы о существовании, единственности и оценках нормы
решения для различных классов нелинейных интегральных
уравнений типа свертки в вещественных пространствах Лебега
$L_p(0,1)$. Эти теоремы охватывают нелинейные уравнения
с ядрами типа потенциала, в том числе и логарифмического
потенциала, а также, в рамках пространства $L_2(0,1)$,
соответствующие линейные интегральные уравнения. Приведены
следствия, иллюстрирующие полученные результаты.
Библиография: 11 названий.
О реализации подграфов случайного графа графами диаметров в евклидовых пространствах
Authors: Kokotkin Andrey ALeksandrovich , Raigorodskii Andrei Mikhailovich
Published: May 2015

Настоящая работа мотивирована классической проблемой Борсука
о разбиении множеств в пространствах на части меньшего диаметра.
В ней найдены точные оценки для максимального числа вершин
индуцированного подграфа случайного графа,
который с высокой вероятностью изоморфен графу диаметров
с данным хроматическим числом в пространстве
любой фиксированной размерности.
Библиография: 21 название.
Гармонический анализ некоторых классов линейных операторов в вещественном банаховом пространстве
Authors: Dikarev Egor Evgen'evich , Polyakov Dmitry Mikhailovich
Published: May 2015

Для некоторых классов линейных ограниченных операторов,
действующих в вещественном банаховом пространстве,
методами абстрактного гармонического анализа получены
условия их разложимости по Фойашу и условия наличия
нетривиального инвариантного подпространства.
Библиография: 15 названий.
Первая краевая задача для сильно эллиптического функционально-дифференциального уравнения с ортотропными сжатиями
Authors: Rossovskii Leonid Efimovich , Tasevich Alla L'vovna
Published: May 2015

Найден ряд необходимых и достаточных условий сильной эллиптичности
функционально-дифференциального уравнения, содержащего в старшей
части ортотропные сжатия аргумента искомой функции. Доказаны однозначная
разрешимость первой краевой задачи, дискретность, полуограниченность и
секториальная структура ее спектра.
Библиография: 15 названий.
Тригонометрические суммы над одномерными квазирешетками произвольной коразмерности
Authors: Shutov Anton Vladimirovich
Published: May 2015

В работе вводится новый класс одномерных квазирешеток -
квазирешетки, параметризуемые сдвигами тора. Для данного класса
рассматриваются тригонометрические суммы по точкам квазирешетки,
зависящие от параметра. Получены нетривиальные оценки
рассмотренных тригонометрических сумм. Для ряда тригонометрических
сумм специального вида получены асимптотические формулы. Доказана
равномерность распределения точек квазирешеток по модулю $h$ для
почти всех модулей. Ранее аналогичные результаты были получены
в частном случае квазирешеток, параметризуемых поворотами
окружности.
Библиография: 23 названия.
The Effect of PIPS on Three Different Types of Dentin: A Surface Observational Study
Authors: Srilatha S , Dixit Vignesh , Vangala Amulya , Jain Paresh
Published: May 2015

Aim

To study the effect of 17% EDTA with PIPS on dentinal surfaces of pediatric, adolescent and geriatric teeth using scanning electron microscope (SEM).

Background data

The debriding ability of an Er:YAG laser system equipped with a new tapered and stripped tip of 400 micron diameter and auxiliary irrigating solutions after mechanical preparation.

Materials and methods

For each group, 20 single rooted human mandibular premolars were selected. The groups were categorized as group 1 pediatric, group 2 adolescent and group 3 geriatric. These groups were further divided as subgroup A (control)—saline and subgroup B—EDTA and PIPS. Access opening was done for all the samples and respective irrigation protocol was followed. The samples were then sectioned and observed under SEM.

Results

The observational study shows that the efficacy of smear layer removal was better in the pediatrics group followed by adolescent and geriatric groups.

Conclusion

The PIPS technique resulted in effective debriding and decontamination of the root canal system in all the three types of dentin.

How to cite this article

Hegde V, Vangala A, Jain P, Srilatha S, Dixit V. The Effect of PIPS on Three Different Types of Dentin: A Surface Observational Study. World J Dent 2015;6(1):5-9.
Evaluation of Effectiveness of Cleaning of Root Canals using Protaper and K3 Rotary Systems: A SEM Study
Authors: Shashikala K , Keshava Prasad BS , Tyagi Anukriti
Published: May 2015

The aim of this in vitro study was to compare the debris and smear layer removal following root canal preparation using two different rotary systems with scanning electron microscope (SEM). The rotary systems used were Protaper and K3. Forty single rooted permanent mandibular premolars were chosen for the study. They were assigned two groups on the basis of instrumentation used.

The teeth were sectioned at the level of cementoenamel junction and instrumented with Protaper in group A and with K3 in group B. The root canals were thoroughly irrigated with 5 ml of 2.5 % NaOCl during instrumentation. After instrumentation, 5 ml of normal saline was used as a final rinse.

The teeth were split longitudinally and the specimens were prepared for SEM evaluation. Scanning electron microscope photomicrographs showed presence of debris and smear layer. The SEM photomicrographs were scored, based on the standard score rating system, and the scores were tabulated accordingly.

The scores obtained from the specimens were subjected to statistical analysis. Results showed opening of dentinal tubules and effective removal of smear layer in group A (Protaper) and no significant difference between both the groups (groups A and B) regarding debris.

How to cite this article

Tyagi A, Prasad BSK, Shashikala K. Evaluation of Effectiveness of Cleaning of Root Canals using Protaper and K3 Rotary Systems: A Sem Study. World J Dent 2015;6(1):20-25.
Force Degradation of Orthodontic Elastomeric Chain due to Commonly Consumed Liquids: An in vitro Study
Authors: Al-Shahrani Ibrahim , Nachan Rameez Asif , Kalia Ajit
Published: May 2015

Introduction

Forces delivered by elastomeric chains are not constant and degrade overtime. The degree of degradation could result in forces that fall below the threshold value, precluding any therapeutic effect. Correct evaluation of degradation of force of these materials under various environmental conditions is the need of hour.

Objective

To analyze and compare the effects of commonly consumed liquids, such as Cola, tea and mouthwash, on the force degradation of orthodontic elastomeric chains was conducted.

Materials and methods

An in vitro study was done to assess factors which affect the decay properties of the three elastomeric modules (Ormco Power Chain, 3M Unitek Alastik Chain and American Orthodontics) in the following food stimulants: black tea, milk, aerated drink, mouthwash and artificial saliva. Two different module lengths (long and short) of each product were used for the initial load-comparison study and force decay was evaluated over 21 days at constant extension and at decreasing extension. Means of percentage change in tensile strength were calculated and analyzed using one way analysis of variance (ANOVA) with Tukey's correction for multiple group comparisons. p < 0.05 was considered to be statistically significant.

Results

The evaluated force degradation in percentage in tensile strength on 21 days post-treatment in tea was significantly higher in product A compared to products B and C with product type short. The evaluated force degradation in percentage in tensile strength on 21 days post-treatment in Cola was significantly higher in products A and C as compared to product B with product type short. The force degradation of product B was significantly less compared to the products A and C initially. However, it degrades at the end of the 21 days and is equivalent with other products.

Conclusion

Irrespective of the solvents used, the force degradation varies for different products.

How to cite this article

Nachan RA, Kalia A, Al-Shahrani I. Force Degradation of Orthodontic Elastomeric Chain due to Commonly Consumed Liquids: An in vitro Study. World J Dent 2015;6(1):31-38.
Macropropagación de Erythrina americana en invernadero: Una herramientapotencial para la restauración de bosques tropicales estacionalmente secos
Authors: Fehling-Fraser Tara C. , Ceccon Eliane
Published: May 2015

La deforestación en México ha hecho que la restauración sea una necesidad urgente.Erythrina americana es un árbol multipropósito, útil para la restauración de bosquestropicales estacionalmente secos (BTES), pero es poco estudiado. La macropropagaciónde esta especie es ventajosa comparada con la reproducción sexual que requiere de semillasescarificadas para germinar. En este estudio se evaluaron los efectos de la aplicaciónexógena de la fitohormona ácido indol-3-butírico en esquejes y del fertilizante fosfatado deliberación lenta (FLL) en el sustrato, sobre el crecimiento de E. americana en invernadero.El experimento tuvo un diseño de cuatro bloques al azar. Diez esquejes se cosecharon portratamiento después de 36, 66, 96 y 126 días de crecimiento. La sobrevivencia, biomasa secatotal (BST), tasa de crecimiento relativo (TCR) y la asignación de recursos (AR) se evaluaron. La sobrevivencia promedio de los esquejes fue alta (95 %). Los tratamientos no afectaron la BST, TCR y AR; sin embargo, la aplicación de FLL en el sustrato mostró valores significativamente (P < 0.05) mayores de biomasa seca radical. Los periodos de crecimiento afectaron la TCR y AR. La macropropagación de E. americana fue exitosa y no requirió cuidados intensivos, por lo que esta técnica puede ser una alternativa viable para proyectos de restauración, principalmente en comunidades con bajos recursos.
Concentraciones de nitrógeno en la precipitación y escorrentíade parcelas con manejo orgánico y convencional
Authors: Cristóbal-Acevedo David , Hernández-Acosta Elizabeth , Álvarez-Sánchez María E. , Maldonado-Torres Ranferi
Published: May 2015

El objetivo de este trabajo fue determinar la concentración y la cantidad de nitratos (NO3-), amonio (NH4+) y nitrógeno mineral (Nmin = NO3- + NH4+) en el agua de precipitación y escorrentía de seis parcelas en Texcoco, Estado de México, durante la temporada de lluvias de los años 2001 y 2010. Para ello, se prepararon seis parcelas de escurrimiento con cultivo de maíz; tres con manejo convencional (MC) y tres con manejo orgánico (MO). Del año 2001 a 2010, las concentraciones promedio de NO3-, NH4+ y Nmin en la precipitación incrementaron a 1.307, 0.833 y 2.140 mg·L-1, respectivamente. Los valores mínimos de NO3-, NH4+ y Nmin también aumentaron a 0.550, 0.970 y 1.640 mg·L-1, respectivamente. En la escorrentía, las concentraciones medias de NO3- en los años 2001 y 2010 fueron mayores con el MC, mientras que las concentraciones de NH4 + fueron más pequeñas. Debido a que en Texcoco, el incremento poblacional del año 2000 al 2010 fue de 31,049 habitantes, se concluyó que el crecimiento poblacional y el desarrollo de la zona tuvieron efecto sobre las cantidades de nitrógeno en la precipitación, y que el MO fue una alternativa para reducir las salidas de nitrógeno por escorrentía.
Distribución espacial de dos especies de encinos y atributos ecológicos del bosque de pino-encino en Ixtlán de Juárez, Oaxaca
Authors: Ruiz-Aquino Faustino , Valdez-Hernández Juan I. , Romero-Manzanares Angélica , Manzano-Méndez Filemón , Fuentes-López Martha E.
Published: May 2015

La estructura y diversidad de un bosque de pino-encino se analizaron en tres unidades de muestreo (UM) de 50 x 50 m, en Ixtlán de Juárez, Oaxaca. Se determinó la distribución espacial de los individuos con diámetro normal ≥ 2.5 cm. Las variables dasométricas se registraron; se calcularon dos índices de importancia estructural (índice de valor de importancia relativa [IVIR] y de valor forestal [IVF]) y tres índices de diversidad (índice de entropía de Shannon-Weiner, número efectivo de diversidad e índice de Sorensen). Se registraron 799 individuos de 11 familias y 19 especies; la familia más abundante fue Fagaceae (628 individuos, cuatro especies). La especie más importante en la UM1 fue Quercus crassifolia (IVIR = 53, IVF = 57). Los valores más altos del IVIR e IVF en la UM2 correspondieron a Q. laurina (IVIR = 48, IVF = 63). En la UM3, la especie más importante fue Q. crassifolia (IVIR = 49, IVF = 62). El análisis de las dos especies en conjunto reveló distribución aleatoria en prácticamente todas las distancias. El patrón agregado de las especies individuales se atribuyó a estrategias de regeneración y prácticas silvícolas. Ambas especies pueden coexistir modificando la importancia estructural y el patrón de distribución horizontal.
Bioprospección de bacterias oxidantes de arsenito de suelo de la Comarca Lagunera
Authors: Rangel-Montoya Edelweiss A. , Balagurusamy Nagamani
Published: May 2015

El arsénico es uno de los metaloides más tóxicos presente en el ambiente y la exposición prolongada a este metal causa efectos crónicos en la salud. Por ello, la búsqueda de alternativas amigables con el medio ambiente, para el tratamiento de agua y suelos contaminados con arsénico es importante. En este trabajo se aislaron cepas bacterianas de suelos con presencia de arsénico en la Comarca Lagunera, para analizar aquellas con capacidad oxidante de arsenito. Las cepas 04-SP1qa y 14-SP1qh de metabolismo quimiolitoautotrófico y quimioheterotrófico, respectivamente, tuvieron mayor actividad de la enzima arsenito oxidasa. Las condiciones óptimas de crecimiento y la actividad enzimática de dichas cepas se investigaron. La cepa 04-SP1qa presentó actividad enzimática específica de 0.162 μmol·min-1·mg-1, constante de Michaelis-Menten (Km) de 3.37 μM y velocidad máxima (Vmax) de 5.20 μM·min-1·mg-1 en condiciones óptimas de pH 8.0 y 40 °C. La cepa 14-SP1qh presentó actividad enzimática específica de 0.16 μmol·min-1·mg-1, Km de 3.70 μM y Vmax de 14.39 μM·min-1·mg-1 a pH 7.0 y 40 °C. Los resultados demostraron la presencia de bacterias oxidantes de arsenito con actividad enzimática en suelos de la Comarca Lagunera, identificando potencial para desarrollar nuevas tecnologías de biorremediación de aguas y suelos contaminados con arsénico en la región.
Identificación del insecto agallador (Trioza rusellae Tuthill) en hojas de Brosimum alicastrum Swartz en Yucatán, México
Authors: Ascencio-Álvarez Ada , Martín-Mex Rodolfo , Tucuch-Haas Jorge I. , Valdez-Carrasco Jorge , Huchin-Poot Emy G. , Andrade-Canto Silvia B. , Gámez-Vázquez A. Josué , Larqué-Saavedra Alfonso
Published: May 2015

El insecto Trioza rusellae Tuthill (Hemiptera-Triozidae) produce agallas en las hojas del árbol de ramón (Brosimum alicastrum Swartz), especie con alto valor nutricional de la península de Yucatán. El insecto fue aislado e identificado a partir de colectas en los municipios de Muna y Sacalum, Yucatán. Los árboles de cinco a 10 años de edad se muestrearon seleccionando ramas con hojas que presentaban agallas. Las muestras se colocaron en bolsas de plástico y se trasladaron al laboratorio confinándolas en jaulas entomológicas. Los adultos se recolectaron con un aspirador manual, mientras que las agallas se disectaron para colectar las ninfas directamente con un pincel (0001). Las muestras se conservaron en alcohol (70 %) y en fijador formol-alcohol-agua (FAA). Las ninfas y adultos de las muestras en alcohol se montaron y observaron en el microscopio estereoscópico. Las muestras en FAA se procesaron y observaron en el microscopio electrónico de barrido (MEB). Como resultado, se obtuvieron fotografías y se identificaron las fases de desarrollo de T. rusellae mediante claves entomológicas.
El sotobosque en la composición y diversidad de áreas bajo manejo forestal en Santa Catarina Ixtepeji, Oaxaca
Authors: Luna-Bautista Lizbeth , Hernández-de la Rosa Patricia , Velázquez-Martínez Alejandro , Gómez-Guerrero Armando , Acosta-Mireles Miguel
Published: May 2015

En el presente estudio se investigó el efecto de las prácticas silvícolas sobre la riqueza, composición y diversidad de las especies arbóreas, herbáceas y arbustivas en un bosque de la comunidad de Santa Catarina Ixtepeji, Oaxaca. Para tal fin, los siguientes tratamientos silvícolas fueron evaluados: corta de selección 1998, aclareo ligero 2011 y árboles padre 1998 y 2011. Los índices de diversidad alfa y beta de las comunidades arbórea, arbustiva y herbácea se estimaron, así como el índice de valor de importancia (IVI) del estrato arbóreo. Los resultados mostraron que el componente herbáceo es el más diverso tanto en rodales bajo manejo silvícola como sin manejo, seguido del componente arbustivo. De acuerdo con el IVI, la especie de mayor importancia ecológica fue Pinus oaxacana Mirov. en todos los tratamientos evaluados, incluyendo el bosque sin manejo. Los resultados indican que el aprovechamiento forestal modifica la riqueza, diversidad y composición de los estratos arbóreo, arbustivo y herbáceo, siendo los dos últimos estratos los que más contribuyen a la diversidad. Por lo anterior resulta importante evaluar el sotobosque, ya que ayuda a dar una mejor explicación de la diversidad vegetal total del bosque.