bluuebunny/crossref_metadata_2025 huggingface dataset:
A Follow-up Study of Overweight Children and Adolescents with Diet Therapy Adjusted by Indirect Calorimetry
Authors: Koglin Gabriela , Nogueira-de-Almeida Carlos Alberto , Beghetto Mariur Gomes , Mello Elza Daniel de
Published: September 2019

Introduction Changes in lifestyle have led to an increase in the prevalence of excess weight. Several interventions intended to reverse this situation have been tested.

Methods We evaluated changes in the z-score for body mass index in children and adolescents after dietary management adjusted by indirect calorimetry. During 1 year, a monthly follow-up was performed on 27 children and adolescents (8–15 years) with overweight/obesity (z-score for body mass index ≥ + 1); body weight and stature measurements were collected at inclusion, at 6, and at 12 months after indirect calorimetry. Each participant received a diet adjusted by the value of indirect calorimetry. The basal metabolic rate (BMR) was evaluated to understand how to behave according to the bodily changes induced by the intervention. For statistical analyses, repeated-measures analysis of variance (ANOVA) were performed.

Results The z-score for body mass index showed a reduction by the end of the study (-0.17 ± 0.05 [p = 0.014]). The BMR dropped during the first 6 months but returned to baseline values after 12 months (p = 0.231).

Conclusion Dietary management adjusted by BMR for obese children and adolescents with excess weight, with monthly appointments, was effective after 12 months of intervention; the weight loss did not cause significant change of BMR in this period.
Licopeno e prevenção do câncer de próstata: Uma revisão integrativa
Authors: Bôto Edilayne Gomes , Kobal Priscila Sala , Ferreira Francisco Valdicélio , Lopes Letícia Bandeira Mascarenhas , Silva Antonia Smara Rodrigues , Nascimento Neto Francisco das Chagas
Published: September 2019

Atualmente, o câncer de próstata configura-se como um importante problema de saúde pública, sendo um dos principais tipos de carcinoma diagnosticados em pacientes do sexo masculino, e tornando-se a causa primordial de morbimortalidade. Estudos têm evidenciado que hábitos e estilo de vida, juntamente com a instalação de um quadro de estresse oxidativo, apresentam-se como importantes fatores implicados no processo de carcinogênese. Em contrapartida, o hábito alimentar tem sido considerado como um aliado significativo na prevenção do câncer, por meio de grupos alimentares com propriedades antioxidantes e anti-inflamatórios capazes de atuar como compostos anticarcinogênicos, incluindo o licopeno, que é considerado um nutriente quimiopreventivo antioxidante. A presente revisão resume alguns resultados relevantes sobre o papel do licopeno na prevenção do câncer de próstata durante os últimos 7 anos. Foram selecionados artigos provenientes das seguintes bases de dados: Scielo, Lilacs, BVS, PubMed, e MEDLINE. De acordo com os critérios de inclusão e de exclusão, foram selecionados 20 artigos internacionais. Em revisões blibliográficas, ensaios clínicos (in vivo e in vitro) evidenciaram a influência da suplementação e do consumo de licopeno a partir de diferentes fontes de produtos à base de tomate e de outros alimentos-fontes na diminuição da viabilidade celular das células prostáticas após o tratamento, além de um aumento da apoptose e da regulação dos níveis transcricionais, apontando o licopeno como um importante fitoquímico. Entretanto, futuras triagens clínicas com o uso de licopeno devem ser realizadas para que seja possível estabelecer recomendações precisas sobre o consumo e a quantidade adequados do referido composto para que este seja utilizado para a prevenção do câncer de próstata.
Future Food: Sustainable Diets for Healthy People and a Healthy Planet
Authors: Wiseman Sheila A. , Dötsch-Klerk Mariska , Neufingerl Nicole , Martins Fernanda de Oliveira
Published: September 2019

The current food system is associated with poor health outcomes, food insecurity, and significant environmental damage. While, globally, more than enough food calories are produced than theoretically needed, this does not guaranty a good quality diet for all. At the same time, the environmental pressures of the current food system threaten several planetary boundaries, which define the environmental limits within which humans can safely operate. This narrative review gives a brief overview of the shortcomings of the current food system regarding its impact on nutrition, health, and the environment. It outlines recent advancements in the development of guidelines for a healthy and sustainable diet and discusses options on how to realize such a dietary transformation, involving all stakeholders in the food value chain.
A Multidisciplinary Approach to Dental Erosion: A Case Report
Authors: Guldag M. Ustun , Buyukkaplan U. Sebnem , Ay Zuhal Yetkin , Katirci Gunseli
Published: September 2019

Chemical erosion is the loss of superficial tooth structure by chemical action in the continued presence of demineralizing agents. This can be prominent in patients with oral habits such as constant citrus ingestion (like lemon chewing), chlorinated swimming pool water or gastrointestinal problems that produce repeated exposure of teeth to gastric acids. In this case report, a multidisciplinary approach to restore the severe wear due to dental erosion by proper techniques and materials was presented. (Eur J Dent 2008;2:110-114)
Adhesion of Two Bonding Systems to Air-Abraded or Bur-Abraded Human Enamel Surfaces
Authors: Sengun Abdulkadir , Orucoglu Hasan , Ipekdal Ilknur , Ozer Fusun
Published: September 2019

Objectives: The purpose of this in vitro study was to evaluate whether mechanical alteration of the enamel surfaces with air abrasion and bur abrasion techniques could enhance the bonding performance of a three step and a self etching adhesive resin systems to enamel.

Methods: 126 extracted lower human incisor teeth were used. The teeth were divided into three groups including 40 teeth each. First group; teeth were used as control and no preparation was made on enamel surfaces, 2nd group; outer enamel surfaces were air abraded, 3rd group; outer enamel surfaces were abraded mechanically with a diamond fissure bur. Cylinder composite resin blocks were bonded to the buccal enamel surfaces with two bonding systems (20 specimens in each group). Bond strengths to enamel surfaces were measured at a cross-head speed of 1 mm/min. The data were analyzed by ANOVA and Duncan Tests. To examine interface composite resin/enamel surfaces at scanning electron microscopy, remaining 6 teeth were used. Fracture analysis was performed using an optical stereomicroscope.

Results: Bond strengths values of Solid Bond were significantly higher than bond strengths of Clearfil SE Bond for all types of enamel (P<.05). Shear bond strength values obtained with Solid Bond (three step system) to three types of enamel surfaces [air-abraded (30.25±7.00 MPa), bur-abraded (29.07±3.53 MPa), control (31.74±7.35 MPa)] were close to each other (P>.05). The macroscopic mode of failures for bonding systems, SB and SE Bond appeared to be adhesive and cohesive in nature.

Conclusions: In order to get better bond strength values with self etching systems, it is advisable to prepare enamel surfaces with bur or air abrasion, but it enamel preparation is not necessary for
three step systems. (Eur J Dent 2008;2:167-175)
Impacted Primary Tooth and Tooth Agenesis: A Case Report of Monozygotic Twins
Authors: Zengin A. Zeynep , Sumer A. Pinar , Karaarslan Emine
Published: September 2019

In the present report, a case of 19 year-old monozygotic twin brothers with similar tooth agenesis
and impacted primary teeth is presented. Both twins (HDH, DHH) had agenesis of ten and eleven teeth (respectively), third molars excluded, consistent with oligodontia and both had four impacted primary teeth and the permanent successors of all these primary teeth were congenitally missing. The occurrence of similarly located tooth agenesis and primary impacted teeth in monozygotic twins may suggest the influence of genetic factors in their etiology. In addition, primary tooth impaction may be related to congenitally missing tooth. (Eur J Dent 2008;2:299-302)
Wound Healing Effects of Arnebia Densiflora Root Extracts on Rat Palatal Mucosa
Authors: Kosger H. Huseyin , Ozturk Mustafa , Sokmen Atalay , Bulut Eray , Ay Sinan
Published: September 2019

Objectives: The aim of this study was to investigate wound healing effects of Arnebia densiflora (Nordm.) Ledeb. root extracts on rat palatal mucosa.

Methods: A 10-mm full-thickness mucosal wounds were created on midline of rats’ palate by using scalpel. Inthe experimental groups, a ten percent extract of A. densiflora roots was topically applied once a day as ointment on the wounds. After wounding, tissue samples from palatal mucosa were harvested at 4, 7, 14 and 21 days and then evaluated histologically.

Results: It was observed that 10% A. densiflora root extract has progressive effects on wound healing in experimental groups.

Conclusions: This study suggests that A. densiflora root extract could be developed as a therapeutic agent for wound healing. (Eur J Dent 2009;3:96-99)
Impacted Teeth and Mandibular Fracture
Authors: Metin Murat , Şener İsmail , Tek Mustafa
Published: September 2019

Objectives: In this retrospective study, we measured the relationship between the presences of impacted or unerupted teeth in the mandible and mandibular fractures.

Methods: The records and radiographs of 41 patients with mandibular fracture associated with impacted or unerupted teeth were examined. The presence of impacted or unerupted teeth were assessed for each patient and related to the occurrence of fractures of mandible.

Results: Patients with fracture in the impacted or unerupted teeth area present had a 1,73 times greater chance of an mandibular fracture than patients with no fracture in the impacted or unerupted teeth area. There was a statistically significant variation in the risk for a mandibular fracture depending on impacted or unerupted teeth presence (x2=5.29, P< .05).

Conclusion: The presence of an impacted or unerupted teeth significantly increases the likelihood of an mandibular fracture. (Eur J Dent 2007;1:18-20)
Stress Analysis of a Maxillary Central Incisor Restored with Different Posts
Authors: Adanir Necdet , Belli Sema
Published: September 2019

Objectives: To evaluate the effects of different post materials on the stress distribution in an endodontically treated maxillary incisor.

Materials and Methods: A pseudo 3-dimensional finite element model was created in a labiolingual cross-sectional view of a maxillary central incisor and modified according to five posts with different physical properties consisting stainless steel, titanium, gold alloy, glass fiber (Snowpost), and carbon fiber (Composipost). A 200 N force was then applied from two different directions; a) vertical load on the incisal edge, b) 45 degree diagonal load above the cingulum location. Stress distribution and values were then calculated by considering the pseudo three dimensional von Mises stress criteria.

Results: Under two loading conditions, post made of steel showed greatest stress concentration at the post/dentin interface followed by titanium, gold alloy, Snowpost and Composipost. However, Composipost, which elastic modulus was closer to the dentin, produced highest stress values at 1/3 cervical area.

Conclusions: Within the limitation of this simulated mechanical analysis, we can conclude that the physical characteristics of posts were important on stress distributions in post and core applications. Glass fiber post revealed more balanced stress distribution under functional forces. (Eur J Dent 2007;2:67-71)
The Release of Elements from Dental Casting Alloy into Cell-Culture Medium and Artificial Saliva
Authors: Can Gülşen , Akpınar Gül , Aydın Ahmet
Published: September 2019

Objectives: The biocompatibility of dental casting alloys is a critical issue because these alloys are in long-term intimate contact with oral tissues. Since the biocompatibility of alloys is not completely known; the release of elements from the alloys has been studied. The aim of this study was to compare the elemental release from dental casting alloy during exposure to artificial saliva and cell-culture medium.

Materials and Methods: Twenty specimens made from Ni-Cr alloy were provided in the form of 5 mm diameter discs, 2 mm in thickness with a 7 mm stem attached to one face to facilitate handling. Ten of twenty samples were polished separately using a conventional technique. The remaining ten samples were left sandblasted with 50 μm Al203. Ten samples (5 polished, 5 sandblasted) were separately placed into cell-culture wells with Dulbecco’s Modified Eagle’s Medium. The other ten samples were placed separately into cell-culture wells with artificial saliva. The samples were subjected in contact with these medium for 30 days. These medium were collected every 7 days. The cell-culture medium and artificial saliva without alloy samples were subjected to elemental analyses as a control. At the end of the exposure time, Atomic Absorption Spectrometry (AAS) was used to determine the release of elements from the alloys into all collected medium. Statistical analyses were assessed with two-way ANOVA

Results: In general, the elemental release occurred with in all medium. The elemental releases of sandblasted alloys were higher than polished alloys. Artificial saliva was found to cause more release from the samples. In both media, Ni released from polished and sandblasted alloys were higher than Cr and Mo.

The results suggest that the release of elements from the alloys might have correlated with the environments and the surface of dental alloy. (Eur J Dent 2007;2:86-90)
Nitrous Oxide Sedation and Bispectral Index
Authors: IŞIK Berrin , TÜZÜNER Tamer , TEZKİRECİOĞLU Melih , ÖZTAŞ Nurhan
Published: September 2019

Objectives: To determine whether bispectral analysis (BIS) changes during nitrous oxide (N2O) sedation in anxious children undergoing extraction of primary teeth.

Methods: In this prospective study 45, ASA physical status I children, aged between 7 to 12 years and scheduled for primary teeth extraction under N2O/O2 sedation are included. At baseline (T0) and during the sedation procedure (T1-6); BIS levels, Ramsay Sedation Scores (RSS), oxygen saturation (Sp02), and heart rate (HR) were recorded at one-minute intervals. Forty percent N2O in O2 was given by a nasal hood, and N2O concentration was enhanced to 60% in a two-minute period. Paired measurements of BIS levels with Observer’s Assessment of Alertness and Sedation (OAA/S) scores were obtained during sedation procedure

Results: Since 5 patients refused application of the nasal hood, a total 40 of the original 45 subjects completed the study. Mean age and weight of the children were 9.5 ± 1.4 years and 23.7 ± 9.7 kg, respectively. Nitrous oxide inhalation produced no changes in BIS levels despite a sedation level in OAA/S scores were observed at 40-60% N2O concentrations

Conclusions:BIS values do not change during N2O/O2 sedation and the BIS monitor is not appropriate to evaluate the depth of sedation provided by N2O/O2 during primary teeth extraction in children. (Eur J Dent 2007;1:240-245)
Endoscopic tattooing of small bowel by double - balloon endoscopy
Authors: Nina Abild , Orhan Bulut
Published: September 2019

Inflammatory vascular polyps that are complicated by bleeding are difficult to diagnose and localise during the operation. With the improvement in the diagnosis of the small bowel tumours with double balloon endoscopy, the preoperative localization of the lesion is essential to undertake appropriate surgery, and to reduce the time for surgery and avoid resection of wrong segment of small bowel. Double balloon endoscopic tattooing of small bowel tumours and lesions is a new modality to ease the surgery when resection of small bowel is indicated. The literature about double balloon endoscopic tattoo is scant. We present a rare case of small bowel polyp that caused bleeding and the successful use of double balloon endoscopic tattoo preoperatively for the localization of the lesion during surgical procedure. (Dig Endosc 2013;4(2):49-51)
Zn vacancy complex-determined filamentary resistive switching characteristics in Au/ZnSe/ITO chalcogenide-based memory cells
Authors: Wang Aoqiu , Dong Jiangpeng , Li Yingrui , Cao Kun , Jie Wanqi
Published: September 2019

ZnSe films with a sphalerite structure and about 100nm grain size were deposited on ITO substrate. 200 stable bipolar resistive switching (RS) cycles were obtained in Au/ZnSe/ITO chalcogenide-based memory cells and it shows an ON/OFF ratio of 10 and retention time of 104 seconds. The conduction mechanism is Ohmic in both low resistance state (LRS) and low voltage region in high resistance state (HRS) while thermionic emission limited conduction (TELC) at high voltage region in HRS. The top electrode (TE) size independence of low resistance implies a filamentary resistive switching mechanism. Photoluminescence (PL) spectroscopy shows a double difference of relative intensity between shallow zinc vacancy state and deep zinc vacancy complex state in HRS and LRS. The explanation for HRS is the dissociation of zinc vacancy complex and the formation of zinc vacancy. Then the shallow acceptor zinc vacancy compensates for the shallow donor contributing the HRS. It is deduced from linear relation of reset voltage and reset power versus temperature that the thermal activation energy of ZnSe film is 0.19 eV, which indicates an over 20nm intertrap distance and the critical temperature for conductive filament (CF) rupture is 305.6K with 0.2mV/s sweep rate, respectively. The component of CF is metal-like shallow donor such as Al or Ga with the help of deep zinc vacancy complex to depress the compensation of shallow zinc vacancy acceptor.
Scaled experiments on cavity confined explosions in limestone and poly(methyl methacrylate)
Authors: Cranch G. A. , Grun J. , Zulick C. , Weaver J. , Fournier K. B. , Compton S. , Dunlop W. , Walton O. , Gran J. K. , Groethe M.
Published: September 2019

A scaled experiment comprising a laser-driven explosion in a cavity is used to characterize the coupling of mechanical energy into the surrounding solid material. Experiments are performed using poly(methyl methacrylate) and dry Salem limestone as the explosion containment blocks materials, in which are milled scaled spherical cavities of various dimensions. Measurements of the coupled shock, taken with fiber optic probes at the cavity wall, show the critical radius where wall deformation transitions from plastic to elastic deformation. These measurements also provide a diagnostic of the air blast, which is validated against GEODYN simulation code. The measurement of the coupled shock amplitude taken farther from the wall in the linear region indicates increased coupling efficiency in small cavities over the range of scaled cavity radii from 6 to 20 m/kt1/3, a phenomenon not previously observed in experiments. A comparison of results taken in this experiment with a parallel experiment using high explosive (HE) as the source shows that coupled shocks generated with HE are characteristically different with much larger amplitude than those produced by a high energy density laser-driven source with the same yield. This experimental technique potentially provides a rapid and cost-effective method to analyze the consequences of a full-scale, low yield, buried explosion.
Subpicotesla scalar atomic magnetometer with a microfabricated cell
Authors: Zhang Rui , Dyer Terry , Brockie Nathan , Parsa Roozbeh , Mhaskar Rahul
Published: September 2019

We demonstrated a scalar atomic magnetometer using a microfabricated Cs vapor cell. The atomic spin precession is driven by an amplitude-modulated circularly-polarized pump laser resonant on the D1 transition of Cs atoms and detected by an off-resonant linearly-polarized probe laser using a balanced polarimeter setup. Under a magnetic field with amplitude in the Earth's magnetic field range, the magnetometer in the gradiometer mode can reach sensitivities below 150fT/Hz, which shows that the magnetometer by itself can achieve sub-100fT/Hz sensitivities. In addition to its high sensitivity, the magnetometer has a bandwidth close to 1 kHz due to the broad magnetic resonance inside the small vapor cell. Our experiment suggests the feasibility of a portable low-power and high-performance magnetometer which can be operated in the Earth's magnetic field. Such a device will greatly reduce the restrictions on the operating environment and expand the range of applications for atomic magnetometers, such as detection of nuclear magnetic resonance in low magnetic fields.
Role of intrinsic and extrinsic defects in H implanted hydrothermally grown ZnO
Authors: Schifano R. , Jakiela R. , Galeckas A. , Kopalko K. , Herklotz F. , Johansen K. M. H. , Vines L.
Published: September 2019

The impact of hydrogen in ZnO is revealed by combining reaction dynamics calculations with temperature dependent Hall (TDH), photoluminescence, and secondary ion mass spectrometry measurements performed on H, 2H, and He implanted ZnO. H and 2H box profiles with a concentration ranging from ∼3×1017 cm−3 to ∼1019 cm−3 and He to produce as much as damage as in the [H] ∼3×1017 cm−3 case were implanted in the samples. The formation of Li lean regions has been observed for [2H] <1019 cm−3 after annealing at 400 °C. This is attributed to Lii presence consequent to the diffusion of Zni created during the H/2H implantation process. Results extracted from the TDH measurements performed prior to the annealing at 400 °C evidence that Lii contributes to an increase in carrier concentration up to ∼1017 cm−3 by providing a donor level with an activation energy of ∼40 meV and thus is very close to the value of ∼47 meV expected for H in the oxygen site. The reaction dynamics analysis evidences that the amount of Lii introduced is decreasing at higher H implantation doses as a result of increasing VZn and H-VZn retrapping, reactions in which Lii is competing with H. Overall, due to Lii formation as well as the presence of Al the maximum percentage of the implanted H or 2H acting as a donor in the investigated range is found to be ≲ 2%, which is considerably lower than previously reported.
Exact solution of three-level model of excited state electron transfer symmetry breaking in quadrupolar molecules
Authors: Ivanov Anatoly I. , Tkachev Vladimir G.
Published: September 2019

An analytical solution of a three-level model of symmetry breaking in excited AL–D–AR quadrupolar triads with an electron donor D and identical electron acceptors AL and AR is derived, in particular, an analytical expression for the dissymmetry parameter (difference in charges, in electron charge units, on the left and right arms of the molecule) is obtained. The model predicts the threshold dependence of the symmetry breaking degree on the parameters of the molecule and its interaction with the solvent. It is shown that for typical molecular parameters, symmetry breaking occurs as a charge transfer from one arm of the molecule to the other with nearly invariable donor charge. A considerable variation of the donor charge in the course of symmetry breaking is predicted for triads with small energy gap between the ground and first excited states. Analysis of the results shows that for a large parameter area, they are very similar to those obtained in a much simpler two-level model, which suggests that instead of a more realistic three-level model, we can use a two-level model to describe symmetry breaking in excited quadrupole molecules. The theory of symmetry breaking effect on the intramolecular vibrational spectra is developed. A comparison of the effect of solvent polarity on IR spectra changes due to an increase in the degree of symmetry breaking with the available experimental data shows that the model adequately describes this phenomenon.
Collective dynamics of capacitively coupled oscillators based on NbO2 memristors
Authors: Zhang Peng , Li Shuai , Bo Yeheng , Liu Xinjun
Published: September 2019

The dynamics of NbO2-based single and coupled oscillators are comprehensively investigated in this study. For single oscillators, the oscillation frequency is shown to have a strong dependence on the source voltage and load resistance. The range of the frequency modulation can be tuned from 2.1 to 6.8 MHz, while the load resistance is fixed at 3 kΩ. For coupled oscillators, rich and complex dynamics including in- and antiphase locking phenomena are carefully explored by using a mutual capacitor. According to different phase trajectories on the phase plane of both voltages across two devices, the evolution of the source voltage vs coupling capacitance phase diagram is shown with load resistance mismatch. Four coupling regions in the phase diagram are recognized, including a butterfly-shaped coupling zone, a linear coupling zone, a transition zone, and an uncoupled zone. As the load resistance mismatch increases from 1.0% to 3.9%, the linear coupling zone gradually disappears while the butterfly-shaped coupling zone gradually expands. When the load resistance mismatch is larger than 9.5%, the butterfly-shaped coupling zone gradually decreases while the uncoupled zone enlarges significantly.
Improved performance of top-gated multilayer MoS2 transistors with channel fully encapsulated by Al2O3 dielectric
Authors: Zou Jiyue , Wang Lisheng , Chen Fengxiang
Published: September 2019

Multilayer two-dimensional molybdenum disulfide (MoS2) field-effect transistors with Al2O3 or HfO2 as top gate dielectric and bottom passivation layer have been comparatively studied. The top-gated MoS2 transistor with Al2O3 as both top gate dielectric and bottom passivation layer exhibits excellent electrical characteristics with an on-off ratio of ∼106, a subthreshold swing of 97 mV dec−1, a low interface-trap density of 1.66×1012 cm−2eV−1, and a high field-effect mobility of 105 cm2 V−1 s−1. All these should be attributed to superior interface quality between Al2O3 top gate dielectric and MoS2, and enhanced dielectric screening effect due to Al2O3 bottom passivation layer.
The structure and thermoelectric properties of tungsten bronze Ba6Ti2Nb8O30
Authors: Jiang Dongting , Ekren Dursun , Azough Feridoon , Day Sarah J. , Chen Kan , Mahajan Amit , Kepaptsoglou Demie M. , Ramasse Quentin M. , Reece Michael J. , Freer Robert
Published: September 2019

Tungsten bronze (TB) structured materials have attracted attention as possible thermoelectrics because of their complex crystal structure. In this work, a new thermoelectric ceramic with a tetragonal tungsten bronze (TB) structure, Ba6Ti2Nb8O30 (BTN), was prepared by the conventional mixed oxide route with some samples processed by Spark Plasma Sintering (SPS). The addition of MnO enabled the fabrication of high density BTN ceramics at a low sintering temperature of 1580 K in air and by SPS. All samples were annealed in a reducing atmosphere after sintering. X-ray diffraction showed that Ba6Ti2Nb8O30 crystallizes with tetragonal symmetry (P4bm space group). High angle annular dark field-electron energy loss spectroscopy analysis confirmed the proposed crystal structure and provided exact elemental distributions in the lattice, showing higher concentrations of Ti in the 2b lattice sites compared to the 8d lattice sites. XPS showed the presence of two spin-orbit double peaks at 207.7 eV in the reduced BTN samples, confirming the presence of Nb4+ ions. By the use of a sintering aid and optimization of the processing parameters, the ceramics achieved a high power factor of 280 μW/m K2 at 873 K. The BTN ceramics showed phonon-glass-type thermal conduction behavior with a low thermal conductivity of 1.7–1.65 W/m K at 300–873 K. A thermoelectric figure of merit (ZT) of 0.14 was achieved at 873 K. This ZT value is comparable with results for many TB thermoelectrics. However, BTN has the advantage of much easier processing.
Laser-induced carbon nanotube microcapsules formation through depletion enhanced deposition
Authors: Lee Hsin-Chieh , Jiang Hong-Ren
Published: September 2019

We report a method to fabricate carbon nanotube (CNT) microcapsule through laser-induced bubble formation in a polyethylene glycol-modified CNT (PEG-CNT) solution in the presence of PEG. A low-power laser is focused on a heat-absorbing surface to create a bubble. While PEG-CNTs in the solution are deposited on the bubble surface to form a microcapsule. The shape stability of microcapsule during swelling process is measured in different concentrations of PEG solutions. The stable CNTs microcapsules form with uniform spherical shape within 8 seconds in a 2% PEG solution, while PEG-CNTs only randomly aggregate without the presence of PEG molecules. Thus, we propose that the deposition of PEG-CNTs is enhanced by PEG molecules due to depletion interaction. Comparing with other methods, assembling PEG-CNTs microcapsules at liquid-air interface of polymer solution by optical heating greatly reduce the time and provide good quality of CNTs microcapsules. This study may enable applications of PEG-CNTs microcapsules.
Molecular dynamics simulations of silicon carbide nanowires under single-ion irradiation
Authors: He Wanzhen , Chen Changqing , Xu Zhiping
Published: September 2019

Understanding irradiation effects is crucial for risk management in space science as well as technological development in material processing, imaging, and radiotherapy. The single-particle event is a stepping stone to this complicate, multiscale problem, which finds relevance in low-dose irradiation where long-term effects are usually concerned. Using molecular dynamics simulations, we explore the responses of crystalline silicon carbide nanowires under single-Ga-ion irradiation. It turns out that the channeling mode is more probable compared to focusing for crystalline surfaces at a normal angle of incidence. We find that the surface of nanowires plays a dual role as sites for both defect nucleation and annihilation, leading to notable diameter-dependent responses to the irradiation. The defects created in a single-ion event are localized within a few nanometers, and there exists a critical diameter for nanowires to be minimally damaged. These results allow quantitative assessment of the irradiation damage of nanostructures and guide their design for irradiation-resistant applications.
Scientists identify ways to decrease oxygen content during additive manufacturing
Authors: Mandel Savannah
Published: September 2019

By studying a titanium aluminide alloy, researchers found that melt pool and particle size effect oxygen content in alloys used to manufacture aeronautical turbine parts.
Through the Backdoor: An Overview of the English East India Company’s Rise and Fall in Safavid Iran, 1616–40
Authors: Razzari Daniel
Published: September 2019

In 1616, the English East India Company expanded its trade into Safavid Iran. The chief merchants in India hoped to acquire a significant share of the Iranian silk trade. After several difficult years in India, the English traders in Surat felt pressure to establish a solid foundation in Iran where they could redirect Iranian silk through Iran’s southern ports and onto Company ships for Europe. Despite Robert Sherley’s promise of wealth and a prosperous market for English cloth, many in the English camp, predominantly Sir Thomas Roe, objected to the silk trade on grounds that it was generally a risky venture. But several leading merchants dismissed Roe’s concerns and pursued the trade without his approval. After early indications that the venture had potential for success, the English silk trade quickly began to falter and finally ceased to exist by 1640. Although its demise was once described as the Company’s failure to produce a substantial quantity of purchasing power—eastern goods, precious metals, and English commodities—this paper explores an alternative explanation that suggests the Company’s failure in Iran was not exclusively the consequence of poor economics.
Azerbaijan between Two Empires: A Contested Borderland in the Early Modern Period (Sixteenth‒Eighteenth Centuries)
Authors: Zarinebaf Fariba
Published: September 2019

The first part of the paper examines the evolution and transformation of Safavid ideology in the context of confessional changes and the role of Turkoman tribes in the Safavid social movement in the Ottoman‒Iranian borderland. The second part examines the impact of Ottoman‒Safavid wars and religious rivalry on the society and economy of Azerbaijan from the sixteenth to the eighteenth centuries.
A Messiah Untamed: Notes on the Philology of Shah Ismāʿīl’sDīvān
Authors: Csirkés Ferenc
Published: September 2019

The article aims to refute a long-standing thesis first put forth by Vladimir Minorsky about how the various copies of the dīvān of Shah Ismāʿīl might reflect shifts and changes in the religious and political landscape of early modern Iran. Contrary to the luminary Russian Orientalist’s claims, it demonstrates and contextualizes the observation that there were several textual traditions and that most of the copies continued to reflect messianism and “extremist” notions of religiosity well into late Ṣafavid times, appealing to a broad audience which was likely made up of Sufi adepts and nomadic Qizilbash, as well as a more refined echelon of courtly connoisseurs, residing in the borderland between the Ottoman lands and Iran. At the same time, it suggests that the main theme of Shah Ismāʿīl’s messianic poetry was sainthood and that in this sense Ṣafavid messianism was not a unique aberration but comparable and connected to such similar ideologies as are known from the Timurid, Ottoman or Mughal context.
Historical changes in the fish communities of the Credit River watershed
Authors: Allen Brett , Mandrak Nicholas E.
Published: September 2019

Watersheds in southern Ontario are of high conservation concern due to their diverse fish communities, productive environments, and threats from numerous anthropogenic stressors. The Credit River watershed, located west of the Greater Toronto Area, has over 60 fish species, and multiple stressors including urbanization, climate change, and aquatic invasive species. This study examines fish community change in the Credit River watershed. Historical fish datasets collected in the watershed from 1954 to 2015 were analyzed to examine richness patterns, temporal trends in species distributions, and faunal similarity at the site and sub-watershed levels. Species richness increased over time at the site and sub-watershed level, displaying predictable richness patterns due to anthropogenic introductions and changes in sampling methods. Species distribution patterns remained largely stable over time with decreases in some species (e.g. Redside Dace) and increases in others (e.g. Largemouth Bass). Faunal similarity also increased over time at the site and sub-watershed level, indicating that the fish communities in the Credit River are homogenizing.
A Hamiltonian-based analytical approach for three-dimensional heat conduction of cylinders with specific mixed boundary conditions
Authors: Rong D L , Zhou Z H , Xu W , Li H Y , Sun J B , Xu X S
Published: September 2019

A novel analytical symplectic method is introduced to investigate the three-dimensional steady-state heat conduction of cylinders with specific mixed boundary conditions (partial temperature and partial heat flux density). By defining the temperature and heat flux density as the mutually dual variables, the Hamiltonian form of governing equations are established. The original problem is reduced into a symplectic eigenproblem which can be solved by the method of separation of variables and a symplectic sub-system. Exact analytical solution is obtained and expressed in terms of symplectic eigensolutions. Comparison studies demonstrate the accuracy of the proposed method. Some new results are given also.
Nonlinear Dynamical Analysis of a Circular Truss Antenna in Thermal Environments
Authors: Wu Ruiqin , Zhang Wei
Published: September 2019

This paper investigates the nonlinear dynamics of the circular truss antenna with considering the thermal effect. The first-order shear deformation shell theory and the Hamilton’s principle are used to establish the mechanical model for the circular truss antenna system. The motion governing equation is derived for the equivalent circular cylindrical shell. For interest in 1:2:3 internal resonances, the continuous system of nonlinear partial governing differential equation of motion is truncated into a three-degree-of-freedom system of ordinary differential equation including quadratic and cubic nonlinearities. From the averaged equations obtained by the method of multiple scales, numerical simulations are presented to investigate the effects of the thermal excitation on the nonlinear responses of the truss antenna system. Bifurcation diagram, phase portraits, time histories, power spectra and max Lyapunov exponents are used to get the numerically results. It is found that there exist period doubling bifurcations, periodic motions and chaotic motions in the system. The numerical results show that the thermal excitation has significant influence on the nonlinear dynamical behaviors of the circular truss antenna system. The findings in this paper is also useful for the nonlinear vibration control of the shell structure.
Vibration of functionally graded Mindlin plate based on a modified strain gradient elasticity theory
Authors: Jiang Jingnong , Wang Lifeng
Published: September 2019

Vibrational behavior of functionally graded (FG) microplates is investigated by a new modified strain gradient Mindlin plate (MSGMP) model. With the help of Hamilton’s principle, the dynamic equation is easily obtained. Furthermore, the general forms of boundary conditions are gotten by using coordinate transformation. The MSGMP model can be degenerated to a couple stress elastic Mindlin plate model or the classical Mindlin plate (CMP) model. Analytical solutions of vibrational problem of a rectangular microplate with four simply supported edges are gotten. Numerical results reveal significant effects of the dimensionless nonlocal parameters, the power law index and vibration mode on the free vibration behavior of FG plate.
270-degree arc-shaped piezoelectric energy converter in uniflow fluid environment
Authors: Gong Ying , Shan Xiaobiao , Yang Zhengbao , Xie Tao
Published: September 2019

Energy harvesting in uniflow fluid environment aims at ambient energy that can be used in water environment for monitor equipment. In this paper, we focus on coupling both bending vibration and torsional vibration to gain better power generation. A novel structure of energy converter(arc-shaped) was designed and manufactured. Meanwhile the influence of vibrator with and without a pelvic fin was tested. Mathematical analyse due to vibration phenomenon and experimental result are reported. The 270-degree arc-shaped ring size piezoelectric ceramic is verified capable of producing an effective voltage over 10 V with the power of 0.5 mW.
Nonlinear transverse vibration of nano-strings based on the differential type of nonlocal theory
Authors: Wang P Y , Zhu C X , Li C , Li S
Published: September 2019

The nonlinear vibration responses of nano-strings are studied based on the theory of Eringen’s nonlocal elasticity. Firstly, the nonlocal differential constitutive model in one-dimensional form which is suitable for a string structure is used, and then the governing equation of motion for the nonlinear vibration of nano-strings is derived by considering the expression of classical Lagrangian strain. In order to solve the non-dimensional nonlinear governing equation of motion, the Galerkin method or Rayleigh-Ritz method is applied, and the nonlinear partial differential equation is approximately transformed into the a set of ordinary differential equations. The ordinary differential equations are then solved by a numerical method, and the nonlinear vibration responses under different time histories are thus obtained. Subsequently, the approximate numerical solution of the nonlinear displacement is solved by the second-order multi-scale method. The nonlinear phenomena in the transverse displacement and the influences of nonlocal scale parameter on the nonlinear vibration characteristics of nano-strings are analyzed accordingly. The results will provide a basis for understanding and controlling the nonlinear dynamics of nano-strings which may act as key components in the booming intelligent nano-systems.
Vibration Suppression of a Cantilevered Piezoelectric Laminated Composite Plate Subjected to Hygrothermal Loads
Authors: Jiang Yue , Xue Ning , Lu Shufeng , Song Xiaojuan
Published: September 2019

In this paper, the vibration suppression strategy for a cantilevered rectangular piezoelectric laminated composite plate is proposed by using the piezoelectric patches, which are attached to the upper and lower surfaces of the plate as the actuators and sensors, respectively. The main contributions of this study is as follows: Firstly, Based on classical laminated plate theory and considering the action of piezoelectric loadings, the dynamics equation of a piezoelectric laminated composite plate subjected to hygrothermal loads is derived by using Hamilton’s principle. The partial differential equations of the piezoelectric laminated composite plate are discretized to a two-degree-of-freedom control equation by using Galerkin method. Secondly, According to the discrete nominal model, a robust controller for the uncertain systems is proposed. Based on the state space equation, the output feedback controller for the system is designed. In the constructed full-dimensional state observer, the estimated state feedback is introduced to construct a closed-loop feedback system. Using the Lyapunov Matrix Inequality (LMI) method and Lyapunov Stability Theory, the feedback gain matrix and observation gain matrix for the system are designed to make the closed-loop system asymptotically stable. Finally, the accuracy and effectiveness of the controller are verified by numerical simulation.
Temperature and strain-rate dependent constitutive model for prediction of thermal cycling life
Authors: Wang Wenjie , Long Xu
Published: September 2019

With temperature cycling as the characteristic working environment of aerospace electronic chips, various constitutive models have been proposed to predict the failure problems of solder joints. However, most researchers adopted only a set of constant parameters to describe the solder joint material properties throughout the temperature cycles, which is obviously unreasonable concerning the possible wide range of working temperature. In fact, with the changing temperature and strain rate, some material parameters will correspondingly evolve as observed in the experiments. In this paper, the framework of the Anand constitutive model is adopted to verify the effect of material parameters of different temperatures and strain rates on the mechanical properties of materials under the scenario of temperature cycling. The lead-containing solder alloy 63Sn37Pb material that is most widely used in aerospace is selected as the solder material for the interconnection structure. In addition, a typical plastic ball grid array (PBGA) packaging structure is used to analyze the influence of the constitutive model parameters on the PBGA thermal fatigue life. Based on experimental data, seven sets of constitutive model parameters with different temperatures (-55°C~125°C) under a region of low strain rate (1×10-4/s) were employed to compare the mechanical properties of the material under temperature cycling. The sensitivity analysis of material parameters is performed and the underlying mechanism are also explained so that the present study can promote the optimization of the constitutive model in numerical simulations in practice.
Preparation and mechanical properties of steel fiber reinforced high performance concrete with copper slag as fine aggregate
Authors: Li X M , Zou S H , Zhao R G , Deng L Y , Ji N , Ren C L
Published: September 2019

High performance concrete is widely used in constructional engineering for its long durability, excellent volume stability, adequate compressive strength and good construction performance. In this paper, a class of high performance concretes are prepared by using copper slag instead of sand as a fine aggregate, and their mechanical properties are tested. Firstly, the high performance concrete specimens with different copper slag content and the steel fiber reinforced ones are individually prepared. Then, the compressive and flexural strength tests for cured high performance concrete specimens are operated according to the CECS13-2009 fiber reinforced concrete test method standard. The test results show that for the high performance concrete with copper slag as fine aggregate, the compressive strength reaches a peak value as the replacement ratio of copper slag to fine sand about 35%, but the flexural strength decreases with increasing copper slag replacement ratio, while for steel fiber reinforced high performance concrete, when the copper slag replacement ratio is about 40%, the concrete has a relatively high compressive strength, flexural strength and toughness. Furthermore, under an equivalent strength condition, the additional steel fiber improves the replacement rate of copper slag in the high performance concrete, so the steel fiber reinforced high performance concrete with copper slag as fine aggregate exhibits a better comprehensive mechanical property.
Influence of Defects on the Mechanical Performances of Super Carbon Nanotube
Authors: Shi Xian , He Xiaoqiao
Published: September 2019

Although nanotechnology processes greatly in recent years, defects are still unavoidable in the production of CNTs and relevant structures, which remarkably reduce their theoretical high-performance. In this study, the influence of defects on the mechanical and fracture performances of SCNT, a CNT-based honeycomb structure, are investigated via molecular dynamics simulations. Defects are revealed to reduce the bearing capacities of SCNTs and the reducing degree significantly relies on both the defect position and the SCNT structure. Defects also modify the cracking path of SCNTs and slow down the fracture propagation, especially for zigzag SCNT. Essentially, defects bring force concentration near the defective area, resulting in the local early fracture. Yet the force concentration degrees of the armchair and zigzag SCNTs are affected by different mechanisms. The force concentration degree of armchair SCNT is displacement-controlled, but that of zigzag SCNT is determined by the force redistribution. The underlying reason for controlling the influence of defect is found to be the force transfer mode of the armchair and zigzag SCNT. With the fact that defects widely exit in the CNT-based networks, this investigation could provide valuable information for the practical applications of CNT-based structures.