bluuebunny/crossref_metadata_2025 huggingface dataset:
Among Birds and Net(Work)S: Material and Social Practices in the Trajectory of Ornithologist Emilie Snethlage (1868–1929)
Authors: Junghans Miriam
Published: September 2016

In the course of her career, German ornithologist Emilie Snethlage (1868-1929), who worked in Brazil in the early twentieth century, was involved in all the steps that characterize the “production” of a specimen for scientific collection: from fieldwork, with the collection and preparation of materials, to their description and publication of results. Each of these stages mobilizes different material practices and sociability networks. During fieldwork or in her museum activities, the fact of being a woman demanded from Snethlage specific strategies for establishing her scientific legitimacy, analyzed in this article, especially her activities related to collecting practices.
Maria Corinta Ferreira (1922–2003?), “Naturalist at the Museu Dr. Álvaro De Castro, Lourenço Marques [Now Maputo], Mozambique,” 1949–1974
Authors: Antunes Luis Pequito
Published: September 2016

In 1940, the naturalist Maria Corinta Ferreira decided to leave the zoology research centre of the board for colonial research (Junta de Investigaçoes Coloniais-JIC), where she felt gender discriminated as a scientist, and compete for the position of naturalist at the Museum Dr. Álvaro de Castro Museum (MAC) located in Lourenço Marques (now Maputo), Mozambique. By benefitting from the knowledge and the entomological collections of museums and scientific institutes in South Africa, for 25 years (1949-1974) she built up a scientific career as a researcher in entomology and achieved international recognition. As a woman, however, she never reached the upper positions in MAC’s hierarchy or in the Scientific Research Institute of Mozambique (IICM), the pretext being her formal academic credentials, notably the fact that she was given the title of Doctor on the basis of her published research, rather than upon completing a PhD.
The effect of different decline angles on the biomechanics of double limb squats and the implications to clinical and training practice
Authors: Richards Jim , Selfe James , Sinclair Jonathan , May Karen , Thomas Gavin
Published: September 2016

Bilateral decline squatting has been well documented as a rehabilitation exercise, however, little information exists on the optimum angle of decline. The aim of this study was to determine the ankle and knee angle, moments, the patellofemoral joint load, patellar tendon load and associated muscle activity while performing a double limb squat at different decline angles and the implications to rehabilitation. Eighteen healthy subjects performed double limb squats at 6 angles of declination: 0, 5, 10, 15, 20 and 25 degrees. The range of motion of the knee and ankle joints, external moments, the patellofemoral/patellar tendon load and integrated EMG of gastrocnemius, tibialis anterior, rectus femoris and biceps femoris were evaluated. As the decline angle increased up to 20 degrees, the range of motion possible at the ankle and knee increased. The joint moments showed a decrease at the ankle up to 15 degrees and an increase at the knee up to 25 degrees, indicating a progressive reduction in loading around the ankle with a corresponding increase of the load in the patellar tendon and patellofemoral joint. These trends were supported by a decrease in tibialis anterior activity and an increase in the rectus femoris activity up to 15 degrees declination. However, gastrocnemius and biceps femoris activity increased as the decline angle increased above 15 degrees. The action of gastrocnemius and biceps femoris stabilises the knee against an anterior displacement of the femur on the tibia. These findings would suggest that there is little benefit in using a decline angle greater than 15-20 degrees unless the purpose is to offer an additional stability challenge to the knee joint.
Transfer of mechanical energy during the shot put
Authors: Błażkiewicz Michalina , Łysoń Barbara , Chmielewski Adam , Wit Andrzej
Published: September 2016

The aim of this study was to analyse transfer of mechanical energy between body segments during the glide shot put. A group of eight elite throwers from the Polish National Team was analysed in the study. Motion analysis of each throw was recorded using an optoelectronic Vicon system composed of nine infrared camcorders and Kistler force plates. The power and energy were computed for the phase of final acceleration of the glide shot put. The data were normalized with respect to time using the algorithm of the fifth order spline and their values were interpolated with respect to the percentage of total time, assuming that the time of the final weight acceleration movement was different for each putter. Statistically significant transfer was found in the study group between the following segments: Right Knee – Right Hip (p = 0.0035), Left Hip - Torso (p = 0.0201), Torso – Right Shoulder (p = 0.0122) and Right Elbow – Right Wrist (p = 0.0001). Furthermore, the results of cluster analysis showed that the kinetic chain used during the final shot acceleration movement had two different models. Differences between the groups were revealed mainly in the energy generated by the hips and trunk.
Examination of YouTube videos related to synthetic cannabinoids
Authors: Fullwood M. Dottington , Kecojevic Aleksandar , Basch Corey H.
Published: September 2016

The popularity of synthetic cannabinoids (SCBs) is increasing the chance for adverse health issues in the United States. Moreover, social media platforms such as YouTube that provided a platform for user-generated content can convey misinformation or glorify use of SCBs. The aim of this study was to fill this gap by describing the content of the most popular YouTube videos containing content related to the SCBs. Videos with at least 1000 or more views found under the search terms “K2” and “spice” included in the analysis. The collective number of views was over 7.5 million. Nearly half of videos were consumer produced (n=42). The most common content in the videos was description of K2 (n=69), followed by mentioning dangers of using K2 (n=47), mentioning side effects (n=38) and showing a person using K2 (n=37). One-third of videos (n=34) promoted use of K2, while 22 videos mentioned risk of dying as a consequence of using K2. YouTube could be used as a surveillance tool to combat this epidemic, but instead, the most widely videos related to SCBs are uploaded by consumers. The content of these consumer videos on YouTube often provide the viewer with access to view a wide array of uploaders describing, encouraging, participating and promoting use.
Research on the relationship between articulation levels and social skills of Turkish children between the ages of 4 and 5 years
Authors: Gumus Nebi Mustafa , Eryilmaz Sevil , Ünsal Selim , Yildirim Ali , Yuksel Sevda , Yuksel Mustafa , Gunduz Mehmet
Published: September 2016

Objective:

This study aims to investigate whether there is a relationship between articulation levels and social skills of normally developing children at the ages of 4 and 5 years and to determine whether articulation levels and social skills are differentiated with regard to variable factors.

Methods:

A relational screening model was used in this study. Eighty-seven boys and 73 girls (160 children in total) who were educated at four preschools were selected according to simple random sampling in Kütahya province, Turkey. The mean age of the children was 4.6 years. The Ankara Articulation Test (AAT) was used to specify the articulation levels of children and the Preschool Social Skills Rating Scale [PSSRS, Okul Öncesi Sosyal Beceri Değerlendirme Ölçeği (OSBED)] was used to evaluate the social skills of the children.

Findings:

The results of the study revealed that the articulation mistakes decrease and social skills increase as the age of children rises. It was found that girls had better results in both social skills and articulation levels than boys. Analysis of the socio-economic statuses of the children showed no significant differences between articulation levels and social skills. Correlation analysis showed that children with articulation disorders have lower social skills rankings than children without articulation disorders, and speech is one of the factors that affect social skills ranking.

Results:

This study is important because of its observations about speech, communication, and social skills in children, as well as for raising awareness among parents and teachers of preschool children.
Book Review Essay
Authors: Barnett Larry D.
Published: September 2016

The Essay reviews a book on law-pertinent empirical research methods and data, but is mainly devoted to placing the subject of the book in context. The Essay thus (i) supplies a quantitative measure of the progress of the social sciences since the start of the twentieth century; and (ii) reports a regression analysis of data to identify variables that account for the frequency with which articles in general-purpose U.S. law reviews have relied on quantitative evidence. The Essay also considers the incorporation of empirical social science into law schools.
Input and Output Normal Forms for Model Order Reduction of Linear Systems
Authors: Perev Kamen
Published: September 2016

This paper considers the problem of model order reduction by transforming the system into input and output normal forms. The reachability gramian in the input normal form is the identity matrix and the observability gramian is a diagonal matrix. Conversely, the observability gramian in the output normal form is the identity matrix and the reachability gramian is a diagonal matrix. The elements of the non-identity diagonal gramians in both normal forms are the squares of the system Hankel singular values. This fact determines the equivalent role which both normal forms play in model order reduction. The implemented projection is nearly orthogonal up to a scaling with the elements of a diagonal matrix. In the paper are shown the relations between the transformed system descriptions and the reachability and observability operators. Major influence for the output energy distribution in the input normal form has the observability operator, while the input energy is uniformly distributed. Alternatively, the input energy distribution in the output normal form is due to the reachability operator action, while the output energy is uniformly distributed. Several experiments are performed confirming the equivalent role of the input and output normal forms in the procedures of system approximation.
A Comparison of Three Soft Computing Techniques, Bayesian Regression, Support Vector Regression, and Wavelet Regression, for Monthly Rainfall Forecast
Authors: Sharma Ashutosh , Goyal Manish Kumar
Published: September 2016

Rainfall, being one of the most important components of the hydrological cycle, plays an extremely important role in agriculture-based economies like India. This paper presents a comparison between three soft computing techniques, namely Bayesian regression (BR), support vector regression (SVR), and wavelet regression (WR), for monthly rainfall forecast in Assam, India. A WR model is a combination of discrete wavelet transform and linear regression. Monthly rainfall data for 102 years from 1901 to 2002 at 21 stations were used for this study. The performances of different models were evaluated based on the mean absolute error, root mean square error, correlation coefficient, and Nash-Sutcliffe efficiency coefficient. Based on model statistics, WR was found to be the most accurate followed by SVR and BR. The efficiencies for the BR, SVR, and WR models were found to be 32.8%, 52.9%, and 64.03%, respectively. From the spatial analysis of model performances, it was found that the models performed best for the upper Assam region followed by lower, southern, and middle regions, respectively.
Placental malperfusion as a possible mechanism of preterm birth in patients with Müllerian anomalies
Authors: Lekovich Jovana , Stewart Joshua , Anderson Sarah , Niemasik Erin , Pereira Nigel , Chasen Stephen
Published: September 2016

Objective:

Müllerian anomalies are associated with increased risk of miscarriage, intrauterine growth restriction (IUGR) and preterm birth. While a commonly implicated cause is restricted expansion of endometrial cavity, alternatively it could be due to abnormal placentation. We sought to examine clinical and histopathologic factors associated with preterm delivery in women with Müllerian anomalies.

Study design:

One hundred and eleven singleton pregnancies in 85 women were analyzed retrospectively. There were 42 pregnancies with bicornaute, 24 with unicornuate, 24 with septate, 19 with didelphys and one each with arcuate and T-shaped uterus. Primary outcomes included gestational age at delivery, placental histopathology, placenta previa and accreta.

Results:

Twenty-eight (25.2%) of pregnancies were delivered prior to term. Of those, only 14 (50%) were due to preterm labor or preterm premature rupture of membranes (PPROM). Histological evidence of placental malperfusion was present in 22% of all pregnancies and those delivered at an earlier median gestational age [34 (IQR 31–37) vs. 37 weeks (IQR 34–39); P=0.001]. Malperfusion was more common in preterm than in full term births (46% vs. 14%; P=0.04). Conversely, inflammation was not more common in preterm compared to term deliveries (17.9% vs. 16.9%; P=0.89). Five pregnancies had placenta previa, three of which were complicated by accreta.

Conclusion:

Placental malperfusion, rather than inflammation, was more commonly associated with preterm births in women with uterine anomalies.
Glucose tolerance in singleton, twin and triplet pregnancies
Authors: Weissman Amir , Drugan Arie
Published: September 2016

Background:

Data regarding the effects of multifetal pregnancy on the incidence of gestational diabetes mellitus (GDM) are inconsistent and even conflicting. Twin pregnancies have been associated with no increase, a marginal increase or a higher incidence of gestational diabetes. In triplet pregnancies, these effects have not been investigated yet.

Objectives:

To analyze the results of the glucose challenge and tolerance tests in singleton, twin and triplet pregnancies.

Study design:

A retrospective database analysis of pregnant women with singletons, twins or triplets who had complete results of the 50 g glucose challenge test (GCT) and the 100 g oral glucose tolerance test (OGTT). The cohort included 12,382 singletons, 515 twins and 39 triplets.

Results:

There were significantly higher rates of abnormal GCTs in twins and triplets compared to singletons (45.4% and 33.3%, respectively vs. 13.7%, P<0.001 and P<0.05). Significantly higher rates of gestational diabetes in twins (10.1% vs. 2.9 %, P<0.001) and triplets (12.8% vs. 2.9%, P<0.05) compared to singletons were observed. Mean glucose levels after the GCT were higher in twins compared to singletons, and even more in triplets (108 mg/dL in singletons vs. 120 mg/dL in twins vs. 129 mg/dL in triplets, P<0.001).

Conclusions:

Glucose intolerance is aggravated in multifetal pregnancies. The likelihood of an abnormal GCT and gestational diabetes is higher in twins and triplets compared to singletons.
Isolation and evaluation of biocontrol agents in controlling anthracnose disease of mango in Thailand
Authors: Rungjindamai Nattawut
Published: September 2016

The agricultural based economy is a core business in Thailand and food export is one of the main sources of income for the Thai population. However, pesticides are overused and misused. As a result there is an urgent need to reduce the use of synthetic chemicals. Biological control offers an alternative to the use of pesticides. Mango (Mangifera indica L.) is widely planted in Thailand and is one of the major cash crops for international export. However, mango suffers from various diseases especially anthracnose, a fungal disease caused by Colletotrichum gloeosporioides. One hundred and twelve isolates of epiphytic microbes were isolated from healthy leaves and fruits of mangoes; this included 93 and 19 isolates of epiphytic bacteria and yeasts, respectively. They were screened for bioactivity against a pathogenic strain of C. gloeosporioides isolated from diseased mangoes using a dual culture technique. Out of 112 isolates, eight isolates exhibited at least 60% inhibition. These isolates were further screened for their inhibition on mango using fruit inoculation. Two isolates reduced the lesion sizes caused by C. gloeosporioides compared to control treatment. These two isolates, based on phenotypical and biochemical tests, were identified as Bacillus sp. MB61 and Bacillus sp. LB72.
Structural determination of Co/TiO2 nanocomposite: XRD technique and simulation analysis
Authors: Mostaghni F. , Abed Y.
Published: September 2016

Synthesis and complex theoretical and experimental studies of Co/TiO2 anatase have been reported. The preparation of Co/TiO2 was carried out by sol-gel method. Distribution of cations among the two tetrahedral and octahedral sites was estimated by analyzing the powder X-ray diffraction patterns by employing Rietveld refinement technique, and the results revealed the existence of tetragonal structure. Band structure and density of states calculations were performed using the first-principles methods. The structural and electronic properties of Co/TiO2 were calculated in the general gradient approximation (GGA). An additional comparison with pure TiO2 anatase allowed us to clarify cobalt doping effect on the electronic structure and the band gap. The band gap of Co/TiO2 was decreased by broadening the valence band as a result of the overlap among Co 3d, Ti 3d, and O 2p states, which made it respond better to visible and solar light.
Effect of TEA on characteristics of CdS/PbS thin film solar cells prepared by CBD
Authors: Sattarian H. , Tohidi T. , Rahmatallahpur SH.
Published: September 2016

In this study, a solar cell with a glass/ITO/CdS/PbS/Al structure was constructed. Both window (CdS) and absorption (PbS) layers were deposited by chemical bath deposition (CBD) method. The CdS window layer was deposited on ITO-glass. The PbS nanocrystalline thin film was prepared with and without triethanolamine on CdS films at bath temperature of 25 °C. CdS and PbS nanocrystals were identified using XRD and SEM. The cells are photosensitive in a large spectral range (at visible and near infrared regions). The cell with absorbing layer obtained from the bath without TEA has higher efficiency with the following parameters: the open circuit voltage (Voc) is 275 mV, short circuit current (Jsc) is 12.24 mA/cm2, maximum voltage (Vmax) is 165 mV and maximum current (Jmax) is 7.11 mA/cm2 with the efficiency η = 1.31 %, fill factor FF is 32 % under the illumination intensity of 90 mW/cm2. The cells have an area of 0.15 cm2.
Effect of cerium on structural and optical properties of ZnO aerogel synthesized in supercritical methanol
Authors: Meddouri M. , Hammiche L. , Slimi O. , Djouadi D. , Chelouche A.
Published: September 2016

Pure ZnO and Ce-doped (5 at.%) ZnO aerogels were prepared by dissociation of dihydrate zinc acetate and cerium nitrate in methanol, followed by drying in supercritical conditions of the solvent. The concentration of zinc acetate solution and the atomic ratio Ce/Zn were fixed at 0.2 mol/L and 0.05 mol/L, respectively. XRD results showed a hexagonal wurtzite structure of ZnO aerogel crystallites and a formation of a separate second phase of ceria cubic phase with fluorite structure and 7.4 nm in size. The introduction of cerium in the solution had a negative effect on the aerogel crystalline quality. The crystallites size was found to be 16 nm in pure ZnO and 27 nm in Ce-doped ZnO aerogels. The grains of Ce-doped ZnO aerogel had torus shaped morphology with hollow centers, but those of pure ZnO were flattened semispheres. The calculated values of different structural parameters showed that cerium ions introduced into the ZnO lattice occupied interstitial sites and Zn ions substituted Ce ones in ceria lattice during the formation process. FT-IR and UV-Vis absorption spectra have not revealed any particularities due to the presence of cerium atoms in ZnO, indicating that Ce (5 at.%) doping of ZnO crystallites synthesized in supercritical methanol did not strongly affect the optical gap of the semiconductor. Micro-Raman studies confirmed the formation of cubic fluorite structure ceria in ZnO aerogel and showed that Raman active modes of ZnO are amplified with the presence of ceria.
Crystal structure of bis(1-ethyl-6-fluoro-4-oxido-7-(piperazin-1-ium-1-yl)-1,8-naphthyridin-1-ium-3-carboxylate-κ2
O,O′)copper(II) benzene-1, 4-dicarboxylate dihydrate, C38H42F2CuN8O12
Authors: Cui Kuo , Wang Liang-Liang , Zhang Wen-Wei , Liu Fu-Xin , Zhang Wen-Jun , Fan Zhuo-Wen
Published: September 2016

C38H42F2CuN8O12, triclinic, P1̅ (no. 2), a = 5.4709(2) Å, b = 10.4100(4) Å, c = 17.3373(6) Å, α = 95.014(2)°, β = 92.041(2)°, γ = 103.223(2)°, V = 955.96(6) Å3, Z = 1, R
gt(F) = 0.0347, wR
ref(F
2) = 0.1125, T = 296 K.
Business Model Innovation: Insights from a Multiple Case Study of Slovenian SMEs
Authors: Marolt Marjeta , Lenart Gregor , Maletič Damjan , Borštnar Mirjana Kljajić , Pucihar Andreja
Published: September 2016

Background and Purpose: Business model innovation (BMI) has become increasingly important, especially in the fast changing business environment. While large enterprises approach these changes systematically, small and medium sized enterprises (SMEs) are left to their own resourcefulness. For the purpose of developing dedicated methods and tools to support different SMEs in addressing these challenges, we have conducted a multiple case study to gain insights into factors that drive SMEs to innovate their BM, how they approach BMI and what changes they made to their BM.

Design/Methodology/Approach: First the framework of analysis was developed based on BMI research frameworks identified in literature review. Then the multiple case studies were conducted following the case study protocol developed by Envision project.

Results: Based on the proposed framework the results of four Slovene SME cases revealed differences between enterprises regarding the drivers behind BMI and changes in usage of the different BMI elements.

Conclusion: Overall, the results suggest all four SMEs, coming from different sectors, are facing BMI challenges without systematically addressing it and without using any dedicated BM ontologies or tools.
Effect of gas counter pressure on shrinkage and residual stress for injection molding process
Authors: Jong Wen-Ren , Hwang Shyh-Shin , Tsai Ming-Chieh , Wu Chien-Chou , Kao Chi-Hung , Huang Yan-Mao
Published: September 2016

Plastic products are common in contemporary daily lives. In the plastics industry, the injection molding process is advantageous for features such as mass production and stable quality. The problem, however, is that the melt will be affected by the residual stress and shrinkage generated in the process of filling and cooling; hence, defects such as warping, deformation, and sink marks will occur. In order to reduce product deformation and shrinkage during the process of molding, the screw of the injection molding machine will start the packing stage when filling is completed, which continuously pushes the melt into the cavity, thus making up for product shrinkage and improving their appearance, quality, and strength. If the packing pressure is too high, however, the internal residual stress will increase accordingly. This study set out to apply gas counter pressure (GCP) in the injection molding process. By importing gas through the ends of the cavity, the melt was exposed to a melt front pressure, which, together with the packing pressure from the screw, is supposed to reduce product shrinkage. The aim was to investigate the impacts of GCP on the process parameters via the changes in machine feedback data, such as pressure and the remaining injection resin. This study also used a relatively thin plate-shaped product and measurements, such as the photoelastic effect and luminance meter, to probe into the impacts of GCP on product residual stress, while a relatively thick paper-clip-shaped product was used to see the impacts of GCP on shrinkage in thick parts. According to the experimental results, the addition of GCP resulted in increased filling volume, improvement of product weight and stability, and effective reduction of section shrinkage, which was most obvious at the point closest to the gas entrance. The shrinkage of the sections parallel and vertical to the flow direction was proved to be reduced by 32% and 16%, respectively. Moreover, observations made via the polarizing stress viewer and luminance meter showed that the internal residual stress of a product could be effectively reduced by a proper amount of GCP.
Evaluation of excess life time cancer risk due to natural radioactivity of the Lignite samples of the Nichahoma, lignite belt, North Kashmir, India
Authors: Ashraf Mudasir , Anu Radha C. , Ahmad Shakeel , Masood Sajad , Ahmad Dar Rayees , Ramasubramanian V.
Published: September 2016

Naturally occurring radionuclides of the 226Ra, 232Th, and 40K present in the lignite samples was measured by using a low-background Pb-shielded gamma spectroscopic counting assembly utilizing NaI(Tl) detector for the measurement and to evaluation the radiation hazard indices and excess life time cancer risk. The average values of specific activity concentrations in the investigated lignite samples was found to be 45.36 Bq kg−1 for 226Ra, 21.42 Bq kg−1 for 232Th, 40.51 Bq kg−1 for 40K and 79.11 Bq kg−1 for Raeq respectively. The average value excess life time cancer risk was found to be relatively higher than the world average. Moreover, the correlation analysis shows the strong dependence of excess lifetime cancer risk on measured dose and the radium equivalent activity.
Characteristic analysis of carbon nanotube thread embedded into three-dimensional braided composite under bending load
Authors: Guo Jian-Min , Gong Li-Ying , Liu Yan
Published: September 2016

In this paper, we introduce an embedded method of carbon nanotube threads (CNTs) in three-dimensional (3-D) braided composite material preform. We investigate the strain sensing properties of CNTs embedded into 3-D braided composites using three-point bend test under different loads. The resistance change rate properties of CNTs in composites under tensile and compressive loading are analyzed in detail. Experimental results show that in the three-point bending process, the resistance of CNTs exponentially increases with the increase of strain until the specimen loading to fracture. Moreover, the residual resistance of CNTs has been observed after unloading. Our experiments have shown that structure health status of 3-D braided composites can be sensed and monitored in real-time using CNTs sensor under bending load. This study provides an experimental basis to lay the foundation for the structural health monitoring system construction of 3-D braided composites.
Predicting the thermal conductivity of polypropylene-multiwall carbon nanotubes using the Krenchel model
Authors: Almasri Atheer M.
Published: September 2016

The thermal conductivity of particulate composite models is well documented in the literature. This paper attempts to fit the experimental data for the thermal conductivity of polymer nanocomposites to a three-phase Krenchel model. The use of this model is applicable for structures that consist of a polymer matrix, a nanofiller, and an interfacial layer around the nanoparticles. The effect of Kapitza’s thermal resistance is implemented in the model along with the assumption that the nanofillers are cylindrical and well connected to each other; however, no parameters related to any type of dispersants or the dispersion techniques are stated in the model. The results of the three-phase Krenchel model were validated using the experimental data of thermal conductivity of multiwall carbon nanotubes embedded in polypropylene matrix nanocomposites. It was found that the model was in good agreement with the experimental thermal conductivity data. Moreover, the results from the model showed that the filler geometrical packing factor was 0.75; consequently, the carbon nanotubes formed bundles of several cylindrical tubes. The length of the interface between the nanotubes and the polymer matrix was around 1 Å. Finally, the thermal conductivity of the composite bundle cylinder was 21.63 W/(m K).
Evaluation of glass-fiber grafted by epoxide-terminated hyperbranched polymer on the effect of mechanical characterization of epoxy composites
Authors: Li Shuiping , Li Yanbo , Zhu Huajun , Lin Qing , Hou Haijun , Lv Tingting , Wu Qisheng , Cui Chong
Published: September 2016

In this study, glass-fiber, grafted by epoxide-terminated hyperbranched polymer (GF-HBPE), was incorporated into epoxy resins for reinforcement purpose. The effects of GF-HBPE content on mechanical properties of the resulting epoxy-based composites, such as tensile strength, percentage elongation at break, flexural strength, and impact strength, were investigated. The experimental results revealed that GF-HBPE substantially outperformed impact resistance in both tensile and flexural tests. For instance, the tensile strength, percentage elongation at break, flexural strength, and impact strength of the epoxy composite with 1 wt% GF-HBPE increase by about 23.6%, 125%, 26%, and 74.5%, respectively, compared to the unmodified epoxy thermoset.
Zika: an old virus with a new face
Authors: Avšic Županc Tatjana , Petrovec Miroslav
Published: September 2016

Zika virus is a mosquito-borne flavivirus that represents a public health emergency at the ongoing epidemic. This obscure virus was limited to sporadic cases in Africa and Asia, until the emergence of Zika virus in Brazil in 2015, when it rapidly spread throughout the Americas. Most Zika virus infections are subclinical or characterized by mild febrile illness. However, neurological complications, including Guillain-Barré syndrome in adults, and congenital anomalies, including microcephaly in babies born to infected mothers, raised a grave concern. Currently, there is no specific antiviral treatment or vaccine available for Zika virus infection. Thus, international public health response is primarily focused on preventing infection, particularly in pregnant women, and on providing up-to-date recommendations to reduce the risk of non-vector transmission of Zika virus.
Quasi-Exact Solutions for Generalised Interquark Interactions in a Two-Body Semi-Relativistic Framework
Authors: Zarrinkamar S.
Published: September 2016

We consider the generalised Cornell, Song-Lin and Richardson interquark interactions in a semi-relativistic two-body basis which originates from the spinless Salpeter equation and is valid for heavy quark limit. In our calculations, due to the complicated nature of arising differential equations, we use the quasi-exact ansatz technique and thereby report the ground-state solution.
B(C6F5)3-guided cyclotrimerization-rearrangement of phenylacetylene. Evidence of the (C6F5)3B−–C(H)=C+Ph intermediate in a 1,1-carboboration reaction
Authors: Nie Wanli , Sun Guofeng , Tian Chong , Borzov Maxim V.
Published: September 2016

In presence of 2,2,6,6-tetramethylpiperidinium ([TMPH]+) chlorotris(pentafluorophenyl)borate ([TMPH]+[ClB(C6F5)3]−, 3), phenylacetylene undergoes an unusual cyclotrimerization-rearrangement leading to tris(pentafluorophenyl)(3,4,5-triphenylphenyl)borate anion (1) as a minor product which can be isolated and purified in a form of salts [1·(TMPH)

n

·Cl
(
n

–1)] (n=3 or 5). A variable temperature and concentration NMR spectroscopy study of 3 in CDCl3 unambiguously demonstrated its ability to liberate free B(C6F5)3, which initiates cyclotrimerization and guides rearrangements towards formation of the tetraarylborate anion 1. For the previously studied “spectator” reaction between phenylacetylene and B(C6F5)3 in CDCl3, 1H, 19F, and 11B NMR-spectral evidence of the (C6F5)3B−–C(H)=C+Ph zwitterionic intermediate of the 1,1-carboboration reaction has been demonstrated. The crystal structures of [1·(TMPH)
3
·Cl
2], the salt 3, and a 1:1 adduct of 1,3,5-tris(4-fluorophenyl)benzene and 2,4,6-tris(pentafluorophenyl)-1,3,5,2,4,6-trioxatriborinane (2) have been established by X-ray diffraction analysis.
Environmentally benign synthesis of methyl 6-amino-5-cyano-4-aryl-2,4-dihydropyrano[2,3-c]pyrazole-3-carboxylates using CeO2 nanoparticles as a reusable and robust catalyst
Authors: Safaei-Ghomi Javad , Asgari-Kheirabadi Mehrnoosh , Shahbazi-Alavi Hossein
Published: September 2016

In this work, we report the synthesis and characterization of CeO2 nanoparticles as an efficient catalyst for the preparation of methyl 6-amino-5-cyano-4-aryl-2,4-dihydropyrano[2,3-c]pyrazole-3-carboxylates via one-pot four-component condensation reaction of dimethyl acetylenedicarboxylate, hydrazine hydrate, malononitrile, and aldehydes in aqueous medium. The use of a non-hazardous organic solvent, easy recovery of the catalyst, compatibility with various functional groups, and high yield of the products make the protocol attractive, greener, and economic.
Simulation of Cylindrical Rod Combustion in High-Pressure Oxygen by Steady-State Jet Model
Authors: Shabunya S. I. , Martynenko V. V. , Ignatenko V. I. , Rostaing J. -C.
Published: September 2016

A steady-state jet model is developed to simulate combustion of iron rods in a high-pressure oxygen atmosphere. The suggested jet mode of combustion is characterized by a constant regression rate of melting interface (RRMI) with its value solely controlled by a melting droplet area between the melting front and the maximum temperature region; experimentally observed periodic droplet detachment does not affect RRMI. An analytical solution in an adiabatic approach and a numerical solution with radiative losses are obtained. The developed model comprises two parameters that simulate mass and heat transfer. The analytical solution contains the product of these coefficients. By analyzing the results of experiments with 1-mm diameter rods, the values of these coefficients were obtained by means of an optimization procedure. The simulation predictions are in agreement with experimental data for different rod diameters and oxygen pressures.
Evaluation of a Near-Adiabatic Compression Process to Increase Fire Safety Within Oxygen Systems, Focusing on Non-Metals
Authors: Ryan Maria , Steinberg Theodore A. , Newton Barry E.
Published: September 2016

One of the most important ignition mechanisms initiating burning in nonmetallic materials, which is directly linked to many large oxygen system fires, is the rapid or near-adiabatic compression of oxygen against a nonmetallic material. Adiabatic compression testing of components and systems is utilized worldwide to determine their compatibility in oxygen systems. However, limited research is available on how adiabatic compression energy is transferred to nonmetallic materials, leading to ignition. By characterizing the transfer of heat from hot compressed oxygen into the non-metal that occurs prior to ignition, an analytical model will be developed to describe this process. A transient model of non-metals in a pure oxygen environment is considered. The development of the mathematical model that simulates the behavior of non-metal ignition when subjected to a near-adiabatic compression process is presented. The ignition model investigates various physical mechanisms, such as heat transfer mechanisms, and reaction rates to determine processes involved during the transfer of heat from hot oxygen to a non-metal prior to ignition. The focus of this model is the gas/solid interface. This research is currently ongoing. Future work will validate the model experimentally before determining maximum safe compression rates to prevent the ignition of different classes of nonmetallic materials. The significance of this research is to increase the fire safety of oxygen systems by establishing a theoretical model to reduce, or eliminate, one of the most common mechanisms of ignition found within oxygen systems—that is, adiabatic compression.
Fatal Accident from an Oxygen Fire in an Indian Steel Plant in 2012: Unresolved Questions
Authors: Chowdhury Kanchan
Published: September 2016

In what could be termed the worst industrial accident involving an oxygen system, a June 2012 fire in India at a steel plant’s oxygen pressure reducing station (PRS) killed all 19 persons present during the station’s planned commissioning. The government of India appointed a committee to investigate the accident. This paper provides details about system configuration and possible operations as well as involved officials’ statements from the committee’s unpublished report. Because the devastating fire left no witness to help chronicle the chain of operational events, the media and the public still do not understand the root cause of the accident. Schematics of the plant and its components, materials of construction, plant conditions, and circumstances that existed during the accident have been described in this paper. Laws of physics and engineering, metallurgical analyses, and a study of the remains of pipes and components are used in discussions. The recorded data that existed in various control rooms of the plant helped to ascertain and explain possible modes of operation attempted by commissioning engineers that eventually resulted in the fire, explosion, and deaths. Exclusive photographs of the accident site and burned components supplement the analysis.
Oxygen Endurance Testing of Oxygen Cylinder Valves
Authors: Kasch T. , Binder C. , Treisch N. , Szypkowski M. , Woitzek A.
Published: September 2016

Cylinder valves for oxygen service that meet the standard DIN EN ISO 10297 should be safe, if properly handled by the user. In the last few years, however, the number of safety incidents with oxygen valves that has been reported to the Federal Institute for Materials Research and Testing (BAM) has increased. According to the incident reports, incorrect handling can be ruled out. People were seriously injured and, in most cases, the causes of these incidents were not clear. Very often such incidents occurred during opening and closing of the valves. Therefore, the technical-scientific community has put the existing methods for type testing more and more into question. Besides other mandatory tests, the aforementioned standard allows the endurance test to be performed with air or with nitrogen. This is appropriate for all other gases but not for oxygen. Up to now, this test did not consider the fact that cylinder valves also contain nonmetallic seat materials and lubricants that may react with oxygen in a dangerous way. Because of this unsatisfactory situation, BAM initiated a research project to perform endurance testing of cylinder valves for oxygen service with oxygen. This test accurately simulates real-life situations when the cylinder valve is opened or closed. The first part of this project was the development of a new oxygen operated endurance tester in accordance with DIN EN ISO 10297. In the second part, endurance testing of valves with air and with oxygen was performed and the results were compared. In addition, another mandatory test of the standard, the oxygen pressure surge test, was carried out on new valves and on valves that had undergone endurance tests with air or oxygen to see the influence on the burn-out safety of such pre-stressed valves. This paper presents the main results of the project. The findings clearly speak for implementing the oxygen endurance test not only with DIN EN ISO 10297 but also with various other standards to increase the burn-out safety of oxygen cylinder valves.
Statistical Considerations for Adiabatic Compression Testing
Authors: Newton Barry E. , Steinberg Theodore A.
Published: September 2016

ASTM G74 has been used for many years to evaluate nonmetallic materials and components for oxygen service. When originally published in 1982, this standard considered a “passing” result to be zero ignitions of a material out of 20 samples tested. However, researchers have recognized that the originally prescribed methodology results in a cumulative binomial confidence of about 36 % for a passing result. As a result, the low confidence for a passing result could be potentially misleading when results are used to qualify materials or components for oxygen service, unless the data is analyzed through available statistical approaches. This paper summarizes research performed to evaluate the statistical aspects of gaseous fluid impact testing so that ignition probabilities can be considered in the test methodology. Data derived by the test method are evaluated by a logistic regression approach in order to describe the behavior of the materials being tested and to compare different materials or test conditions. Therefore, the statistical aspects of the test are shown to be crucial to understanding and applying the data obtained. This paper demonstrates that the ASTM G74 test and all international tests of a similar nature because all use the same test embodiment and are inherently probabilistic and subject to variability that seems random without application of appropriate statistical analysis. However, meaningful results can be developed when the appropriate statistical tools are utilized. Logistic regression analysis is only one available method to analyze binomial data (ignition/no-ignition); but it is a powerful tool that can help to bring clarity to the trends in data that are obscured by sometimes seemingly random behavior.
Improved ASTM G72 Test Method for Ensuring Adequate Fuel-to-Oxidizer Ratios
Authors: Juarez Alfredo , Harper Susana A.
Published: September 2016

ASTM G72/G72M-15, Standard Test Method for Autogenous Ignition Temperature of Liquids and Solids in a High-Pressure Oxygen-Enriched Environment, is currently used to evaluate materials for ignition susceptibility driven by exposure to external heat in an enriched oxygen environment. Testing performed on highly volatile liquids such as cleaning solvents has proven problematic due to inconsistent test results (nonignitions). Nonignition results can be misinterpreted as favorable oxygen compatibility, although they are more likely associated with inadequate fuel-to-oxidizer ratios. Forced evaporation during purging and inadequate sample size were identified as two potential causes for inadequate available sample material during testing. In an effort to maintain adequate fuel-to-oxidizer ratios within the reaction vessel during a test, several parameters were considered, including sample size, pretest sample chilling, pretest purging, and test pressure. Tests on a variety of solvents exhibiting a range of volatilities are presented in this paper. A proposed improvement to the standard test protocol as a result of this evaluation is also presented. Execution of the final proposed improved test protocol outlines an incremental step method of determining optimal conditions using increased sample sizes while considering test system safety limits. The proposed improved test method increases confidence in results obtained by utilizing the ASTM G72 autogenous ignition temperature test method and can aid in the oxygen compatibility assessment of highly volatile liquids and other conditions that may lead to false nonignition results.
An Improved Approach for Analyzing the Oxygen Compatibility of Solvents and Other Oxygen-Flammable Materials for Use in Oxygen Systems
Authors: Harper Susana A. , Juarez Alfredo , Peralta Stephen F. , Stoltzfus Joel , Arpin Christina Piña , Beeson Harold D.
Published: September 2016

Solvents used to clean oxygen system components must be assessed for oxygen compatibility because incompatible residue or fluid inadvertently left behind within an oxygen system can pose a flammability risk. The most recent approach focused on solvent ignition susceptibility to assess the flammability risk associated with these materials. Previous evaluations included ambient pressure liquid oxygen (LOX) mechanical impact testing (ASTM G86) and autogenous ignition temperature (AIT) testing (ASTM G72). The goal in this approach was to identify a solvent material that was not flammable in oxygen. As environmental policies restrict the available options of acceptable solvents, it has proven difficult to identify one that is not flammable in oxygen. A more rigorous oxygen compatibility approach is needed in an effort to select a new solvent for NASA applications. NASA's White Sands Test Facility proposed an approach that acknowledges oxygen flammability yet selects solvent materials based on their relative oxygen compatibility ranking, similar to that described in ASTM G63-99. Solvents are selected based on their ranking with respect to minimal ignition susceptibility, damage, and propagation potential, as well as their relative ranking when compared with other solvent materials that are successfully used in oxygen systems. Based on these comparisons, in which solvents exhibited properties within those ranges seen with proven oxygen system materials, it is believed that Solstice PF, L-14780, and Vertrel MCA would perform well with respect to oxygen compatibility.
Studies of Type 301 Stainless Steel Columns
Authors: Dubuc Julien , Krivobok V. N. , Welter Georges
Published: September 2016

The study of the behavior in compression of structural elements made of type 301 austenitic stainless steel has been carried out. Buckling tests on columns of this material have shown that experimental values for slenderness ratios above about 40 agree pretty well and are only slightly higher than those predicted by Watter and Lincoln (I).4 For slenderness ratio values below about 40, buckling of the wide faces, rather than of the column as a whole, occurred for stresses near to those calculated by Watter and Lincoln for the particular type of cross-section used in the present work.

“Creep” (that is, straining under constant load at room temperature) or cycling the applied load has no effect on the final stress-strain compression curve: that is to say, the curve obtained in the above manner is identical with the curve that would have been obtained had there been no creep or cycling. However, the stress-strain relationship in the column after previous stressing and then relieving the stress to zero is entirely different from the original relationship. In the instance of the second loading, the ratio of strain to stress becomes linear almost up to the previously applied stress.

The beneficial effects of heat treatment at relatively low temperatures on the stress-strain relationship in compression have been uncovered.
Axial Stress Fatigue, Creep, and Rupture Properties of Unnotched and Notched Specimens of Heat Resistant Alloys
Authors: Vitovec F. H. , Lazan B. J.
Published: September 2016

Fatigue, rupture, and creep data at various temperatures obtained under various combinations of mean and alternating stress are presented for the alloys Stellite 31, 6.3 per cent molybdenum-Waspalloy, Inconel X-550, 16-25-6 Timken, Lapelloy, and stainless steel type 403. Tests were performed under axial stress on unnotched specimens and specimens having theoretical stress concentration factors of 2.4 and 3.4. The data are presented as stress range diagrams to show the effect on the fatigue and creep properties of specimen notch, temperature, ratio of alternating-to-mean stress, and stress magnitude. The role of both creep and fatigue as design factors and the relation of notch sensitivity to loading conditions are discussed with particular reference to temperature and ratio of alternating-to-mean stress.