bluuebunny/crossref_metadata_2025 huggingface dataset:
Environmental impact assessment of plasma‐assisted and conventional ammonia synthesis routes
Authors: Anastasopoulou Aikaterini , Keijzer Robin , Patil Bhaskar , Lang Jürgen , van Rooij Gerard , Hessel Volker
Published: April 2020

The importance of ammonia in the fertilizer industry has been widely acknowledged over the past decades. In view of the upcoming increase of world population and, in turn, food demand, its production rate is likely to increase exponentially. However, considering the high dependence on natural resources and the intensive emission profile of the contemporary ammonia synthesis route, as well as the rigid environmental laws being enforced at a global level, the need to develop a sustainable alternative production route becomes quite imperative. A novel approach toward the synthesis of ammonia has been realized by means of non‐thermal plasma technology under ambient operating conditions. Because the given technology is still under development, carrying out a life cycle assessment (LCA) is highly recommended as a means of identifying areas of the chemical process that could be potentially improved for an enhanced environmental performance. For that purpose, in the given research study, a process design for a small‐scale plasma‐assisted ammonia plant is being proposed and evaluated environmentally for specific design scenarios against the conventional ammonia synthesis employing steam reforming and water electrolysis for hydrogen generation. On the basis of the LCA results, the most contributory factor to the majority of the examined life cycle impact categories for the plasma‐assisted process, considering an energy efficiency of 1.9 g NH3/kWh, is the impact of the power consumption of the plasma reactor with its share ranging from 15% to 73%. On a comparative basis, the plasma process powered by hydropower has demonstrated a better overall environmental profile over the two benchmark cases for the scenarios of a 5% and 15% NH3 yield and an energy recovery of 5% applicable to all examined plasma power consumption values.
First report of Plectosphaerella plurivora causing root rot disease in Panax notoginseng in China
Authors: Han Li , Zhou Xuan , Zhao Yiting , Wu Lixia , Ping Xiangrui , He Yunlu , Peng Sheng , He Xiahong , Du Yunlong
Published: April 2020

Panax notoginseng is a highly valuable herb, but root rot disease severely impairs its development and decreases the yield and quality of roots. In this study, a fungal isolate (3A‐2‐2) was obtained from P. notoginseng seedlings with root rot symptoms and was identified as Plectosphaerella plurivora based on morphological characteristics and molecular analysis. The fungal isolate 3A‐2‐2 could cause root rot disease and be re‐isolated, fulfilling Koch's postulates. This is the first study to report on root rot disease caused by P. plurivora on P. notoginseng in China.
Role of NaCl level on the handling and water mobility in dough prepared from four wheat cultivars
Authors: Avramenko Nicole A. , Hopkins Erin J. , Hucl Pierre , Scanlon Martin G. , Nickerson Michael T.
Published: April 2020

In bread, NaCl plays a number of roles including improving flavor, functionality, dough handling, and prevention of sticky dough. Its reduction can create significant processing challenges. As such, the dough handling properties for four wheat cultivars (Pembina, Roblin, McKenzie, and Harvest) were investigated as a function of NaCl (0–4%) level. In terms of dough rheology, both cultivar and NaCl level were significant factors. The maximum deformation (Jmax) in the dough decreased with increasing NaCl levels, indicating that the gluten network became stronger so that it was able to resist the imposed stress. For extensibility, increasing the levels of NaCl resulted in increased resistance to extension for all cultivars. Dough stickiness was shown to be both cultivar and salt level dependent, with weaker cultivars showing higher stickiness. Findings for water association indicated that with the addition of NaCl there was less free water among the different cultivars and an increase in the water associated with the starch‐fraction. Dough morphology measurements supported rheology trends; the stronger dough producing cultivars created more elongated protein polymers with a unidirectional network whereas the weaker cultivars created porous multidirectional networks. Overall, Pembina and Roblin formed stronger gluten networks than McKenzie and Harvest, however, the effect of NaCl level was shown to be cultivar dependent. Findings indicate that careful cultivar selection will help mitigate challenges in dough handling within a reduced NaCl environment.
The fate of páramo plant assemblages in the sky islands of the northern Andes
Authors: Peyre Gwendolyn , Lenoir Jonathan , Karger Dirk N. , Gomez Monica , Gonzalez Alexander , Broennimann Olivier , Guisan Antoine
Published: April 2020

Aims

Assessing climate change impacts on biodiversity is a main scientific challenge, especially in the tropics. We predicted the future of plant species and communities on the unique páramo sky islands by implementing the Spatial Explicit Species Assemblage Modelling framework. Specifically we: (a) calculated species’ maximum dispersal distance; (b) modelled species’ present and future distributions up to 2100; and (c) assembled models into plant communities. The final vulnerability assessment was based on a multi‐dimensional evaluation that considered the species, local plant community and sky island levels.

Location

Ecuadorian super‐páramo (>4,200 m).

Methods

Using species trait data, the maximum dispersal distance of 435 species was calculated. Species distribution models (SDM) were fitted to obtain current and future distribution predictions based on dispersal and bioclimatic factors. The final current assemblages and those for 2100 were achieved by stacking all probabilistic SDMs and applying the probability ranking rule. The vulnerability of each sky island was evaluated by quantifying richness and composition changes.

Results

Maximum dispersal distances ranged between 0.008 m/year and 6,027 m/year, and across all scenarios, 70% of models showed a net loss in species distribution, while 9% of all species were predicted to undergo extinction in Ecuador by 2100. Local richness was estimated to decrease by 56.63% on average, and compositional changes in each sky island suggested a mean loss of 64.74% of their original species pool against a 12.97% gain. Finally, 5% of the sky island floras reconverted from high‐elevation to low‐elevation species. These numbers were usually more important for high‐elevation species and the mountains Pichincha, Ilinizas and Antisana.

Conclusions

This methodological pioneer study provides novel insight into the future of páramo biodiversity. Significant losses in species distribution and changes in community richness and composition suggest drastic impacts and call for further research considering additional factors, such as land use. Finally, we recommend focusing monitoring and conservation strategies on the northern Ecuadorian sky islands as a priority.
The impact of coronavirus infectious disease 19 (COVID‐19) on oral health
Authors: Dziedzic Arkadiusz , Wojtyczka Robert
Published: April 2020

Health services across the world face an unprecedented situation as a result of a global COVID‐19 outbreak. Urgent joined research efforts regarding the SARS‐COV‐2 rapid tests, accurate diagnosis, especially early recognition, and effective treatment of life‐threatening complications would be highly desirable for humanity and medical workforce all over the world that try to combat a current global pandemic threat. Due to indirect complex effect, intensified COVID‐19 therapies and multi‐drug treatment, it is believed that some oral conditions could be aggravated by COVID‐19 disease, particularly those with autoimmune aetiology, linked to compromised immune system or long‐term pharmacotherapy.
Electronic cigarettes: A narrative review of the implications for the pediatric anesthesiologist
Authors: Lemay Francois , Baker Paul , McRobbie Hayden
Published: April 2020

The use of electronic cigarettes (EC) is increasing and the number of EC publications is rapidly growing. While some health organizations focus on the harmful effects of using EC (vaping), others promote the benefits of ECs as a less harmful alternative to smoking tobacco. There is concern that vaping might have adverse respiratory consequences for pediatric patients facing anesthesia and intensive care. This narrative review summarizes current knowledge and recommendations regarding the risks of EC relevant to the anesthesiologist and the use of ECs as a step‐down option from tobacco. We provide guidance on the management of vaping patients in the perioperative period.
The Ca2+‐Regulated Photoprotein Obelin as a Tool for SELEX Monitoring and DNA Aptamer Affinity Evaluation
Authors: Krasitskaya Vasilisa V. , Goncharova Natalia S. , Biriukov Vladislav V. , Bashmakova Eugenia E. , Kabilov Marsel R. , Baykov Ivan K. , Sokolov Aleksey E. , Frank Ludmila A.
Published: April 2020

Bioluminescent solid‐phase analysis was proposed to monitor the selection process and to determine binding characteristics of the aptamer–target complexes during design and development of the specific aptamers. The assay involves Ca2+‐regulated photoprotein obelin as a simple, sensitive and fast reporter. Applicability and the prospects of the approach were exemplified by identification of DNA aptamers to cardiac troponin I, a highly specific early biomarker for acute myocardial infarction. Two structurally different aptamers specific to various epitopes of troponin I were obtained and then tested in a model bioluminescent assay.
Effects of ammonia on shrimp physiology and immunity: a review
Authors: Zhao Mingming , Yao Defu , Li Shengkang , Zhang Yueling , Aweya Jude Juventus
Published: April 2020

The rapid expansion in shrimp farming comes with problems such as inadequate culture technology, disease outbreak, water pollution and other environmental degradation‐related problems. Prominent among these is the level of ammonia, which has been rising steadily in the last couple of years, mainly due to farming practices and other anthropogenic activities, and therefore has had consequent effects on marine life, especially shrimp. While optimal ammonia levels are a good source of nitrogen for marine phytoplankton that increases the level of dissolved oxygen in water as well serves as food for shrimp, high levels of ammonia are harmful to shrimp. When shrimp pond ammonia levels go beyond the tolerance limits, it inhibits chitinase expression, moulting, growth, phenoloxidase and haemolymph antimicrobial activity, thereby attenuating shrimp innate immune response. In this review, we bring together recent information on the effects of ammonia stress on the growth, physiology, biochemistry, ammonia‐metabolizing enzymes and immunity of shrimp. We also propose areas of research that can be explored in the breeding of new ammonia‐tolerant and disease‐resistant shrimp with robust immune and/or physiological systems that could withstand environmental stress and pathogens.
Causal Discovery of Gene Regulation with Incomplete Data
Authors: Foraita Ronja , Friemel Juliane , Günther Kathrin , Behrens Thomas , Bullerdiek Jörn , Nimzyk Rolf , Ahrens Wolfgang , Didelez Vanessa
Published: April 2020

Causal discovery algorithms aim to identify causal relations from observational data and have become a popular tool for analysing genetic regulatory systems. In this work, we applied causal discovery to obtain novel insights into the genetic regulation underlying head-and-neck squamous cell carcinoma. Some methodological challenges needed to be resolved first. The available data contained missing values, but most approaches to causal discovery require complete data. Hence, we propose a new procedure combining constraint-based causal discovery with multiple imputation. This is based on using Rubin's rules for pooling tests of conditional independence. A second challenge was that causal discovery relies on strong assumptions and can be rather unstable. To assess the robustness of our results, we supplemented our investigation with sensitivity analyses, including a non-parametric bootstrap to quantify the variability of the estimated causal structures. We applied these methods to investigate how the high mobility group AT-Hook 2 (HMGA2) gene is incorporated in the protein 53 signalling pathway playing an important role in head-and-neck squamous cell carcinoma. Our results were quite stable and found direct associations between HMGA2 and other relevant proteins, but they did not provide clear support for the claim that HMGA2 itself is a key regulator gene.
The disembedded digital economy: Social protection for new economy employment in China
Authors: Chen Bin , Liu Tao , Guo Lin , Xie Zhenglin
Published: April 2020

This research focuses upon employment in the new economy, exploring labour protection and social protection in the digital age in China. Through an empirical survey conducted in three Chinese cities, social insurance and the labour rights of employees in the digital economic sector, such as gig employment, e‐commerce, and various other forms of online employment, have been examined in‐depth. This study reveals new regulatory loopholes in the digital labour market, which have substantially eroded the basis of social policy arrangements in China, “softening” participation in social insurance branches and compliance with labour regulations remarkably. Drawing upon the theoretical concepts of Polanyi on embeddedness and disembeddedness, we argue that the digital employment sector in China has been increasingly disembedded from social institutions and social control. The new configuration in the digital field of social policy requires novel conceptual models and institutional settings to cope with increasing social risks in virtual spaces.
Improving the quality of statistical questions posed for group comparison situations
Authors: Frischemeier Daniel , Leavy Aisling
Published: April 2020

Posing statistical questions is a fundamental and often overlooked component of statistical inquiry. In this paper, we provide an overview of shared understandings regarding what constitutes a good statistical question. We then describe three approaches—a checklist for improving statistical questions, a three‐phase feedback activity, and a matching game—that we find useful with preservice teachers to support the development of high‐quality statistical questions for the comparison of data sets.
Unconventional diets and nutritional supplements are more common in dogs with cancer compared to healthy dogs: An online global survey of 345 dog owners
Authors: Bianco Adriana V. , Abood Sarah , Mutsaers Anthony , Woods J. Paul , Coe Jason B. , Verbrugghe Adronie
Published: April 2020

This survey aimed to investigate and compare diet type and supplement use between dogs (Canis lupus familiaris, L.) with cancer and a population of owner‐reported healthy dogs and to assess the sources of information dog owners consult. Respondents were mainly from English‐speaking countries. Dogs were considered healthy (N = 213) if owners reported them to be in good health. Dogs were included in the cancer group (N = 132) if the owner reported that their dog had been diagnosed with cancer. An online survey was distributed to clients presenting to a tertiary oncology service, clients presenting to a local primary care veterinary practice, and through social media. Owners of dogs with cancer spent more time researching pet health (P < .001), pet nutrition (P < .01) and nutritional supplements (P < .001) than owners of healthy dogs. While veterinarians were most commonly reported to be an information source for both groups, owners of healthy dogs more likely consulted pet stores and owners of dogs with cancer tended more to social media groups and blogs. Healthy dogs were more likely fed commercial dry food (P < .001), whereas homemade cooked (P < .001) and raw diets (P < .05) were more prevalent among dogs with cancer. Supplement use, especially cannabidiol products, mushroom extracts or turmeric/curcumin, was also more common for this group (P < .001). Alternative diets and supplements were more popular among owners of dogs with cancer compared to owners of healthy dogs. These findings highlight the need for nutritional counselling and education of pet owners regarding nutrition‐related topics, especially when their dog is diagnosed with cancer.
Outbreak of human infections with uncommon Salmonella serotypes linked to pet bearded dragons, 2012–2014
Authors: Kiebler Craig A. , Bottichio Lyndsay , Simmons Latoya , Basler Colin , Klos Rachel , Gurfield Nikos , Roberts Elizabeth , Kimura Akiko , Lewis Linda S. , Bird Kiyomi , Stiles Felicia , Schlater Linda K. , Lantz Kristina , Edling Thomas , Barton Behravesh Casey
Published: April 2020

Reptiles are one of the fastest growing sectors in the United States pet industry. Reptile‐associated salmonellosis (RAS) continues to be an important public health problem, especially among children. We investigated an outbreak of human Salmonella infections resulting from serotypes Cotham and Kisarawe, predominately occurring among children. An outbreak of illnesses was identified in persons with exposure to pet bearded dragon lizards. Human and animal health officials, in cooperation with the pet industry, conducted epidemiologic, traceback and laboratory investigations. Onsite sampling was conducted at two US breeding facilities, one foreign breeding facility, and a large pet retail chain. A total of 166 patients in 36 states were identified with illness onset dates from 02/2012–06/2014. The median patient age was 3 years (range, <1–79 years), 57% were aged ≤5 years, and 37% were aged ≤1 year. Forty‐four patients (37%) were hospitalized, predominantly children. Sampling at breeding facilities and a national pet store chain resulted in isolation of outbreak serotypes at each facility; isolation proportions ranged from 2%–24% of samples collected at each facility.Epidemiologic, microbiologic and traceback evidence linked an outbreak of uncommon Salmonella serotypes to contact with pet bearded dragons. The high proportion of infants involved in this outbreak highlights the need to educate owners about the risk of RAS in children and the potential for household contamination by pet reptiles or their habitats. Strategies should be developed to improve breeding practices, biosecurity and monitoring protocols to reduce Salmonella in the pet reptile trade.
Effects of medium variation and fermentation time on the antioxidant and antimicrobial properties of Kombucha
Authors: Vohra Batul Moiz , Fazry Shazrul , Sairi Fareed , Babul-Airianah Othman
Published: April 2020

Kombucha is a traditional fermented drink and has recently gained popularity due to its numerous claims on therapeutic effects. It is prepared by sweetening black tea and fermented using a symbiotic culture of acetic acid bacteria and yeasts known as SCOBY. The drink can also be brewed using different type of tea and carbon sources. An investigation was conducted to characterize the antioxidant and antimicrobial properties of kombucha by variation of carbon sources: white sugar (S), jaggery (J) and Kelulut honey (H) in black tea (BT) and green tea (GT) media over a period of 7, 14, 28 and 60 days. The antioxidant and antimicrobial efficacy were tested post fermentation. All samples shown the highest value of DPPH inhibition for antioxidant activity at 7 days of fermentation but subsequently decreased with longer fermentation time except for the combination of green tea with jaggery (GT+J). Fermentation of green tea with white sugar (GT+S) showed the highest value with 84%. On the other hand, black tea with jaggery (BT+J) showed least DPPH activity, 9%. Fermentation with green tea demonstrated a higher antioxidant activity compared to black tea, whereas fermentation of any tea with jaggery showed the least antioxidant activity in comparison to white sugar and honey. Thus, it can be said that extended periods of fermentation reduce the DPPH inhibition of kombucha and jaggery itself as carbon source shows an interesting property. Antimicrobial activity was tested using disk diffusion method against E. coli, S. aureus, P. aeruginosa, B. subtilis and S. marcescens. The efficacy increases with time of fermentation for all combinations. Combination of black tea with all carbon sources was found to have most antimicrobial activity.
Comparison of semen characteristics between indigenous and Amo breeds cockerel of Gombe State, Nigeria
Authors: Usman Tijjani Haruna , Sir Saleh Mohammed , Sani Ma’aruf Bashir
Published: April 2020

The experiment was carried out to compare the semen characteristics of indigenous and Amo strains of cockerel at poultry unit of teaching and research farm of Federal University of Kashere, Gombe State, Nigeria. Semen samples were collected from nine indigenous and nine Amo breeds of cockerel at three days interval for two weeks using abdominal massage technique. Semen samples were examined macroscopically for semen colour, pH and ejaculation volume. Then, microscopic observation was carried for sperm concentration, mass motility, progressive motility, live and dead sperms percentage, normal and abnormal sperm, all for semen characteristics. The results showed a significant difference (P ≤ 0.05) between mass motility, progressive motility, sperm concentration and head defects of 4.85 ± 0.27 to 4.37 ± 0.19, 95.13 ± 0.43 to 81.63 ± 1.15%, 4.93 ± 1.84 to 3.40 ± 1.07×109/ml and 2.96 ± 0.17 to 3.44 ± 0.12% for indigenous and Amo breeds of cockerel, respectively. There were no significant differences observed as semen colour, ejaculate volume, semen pH, live / dead normal sperm neck (mid-piece), tail defects and sperm total abnormalities were found to be 2.85 ± 0.07 to 2.00 ± 0.090.21 ± 0.17 to 0.20 ± 0.02 /ml, 88.85 ± 0.58 to 72.70 ± 0.54% /ml, 11.14 ± 0.58 to 27.29 ± 0.54%, 81.00 ± 0.78 to 66.22 ± 0.61%,9.03 ± 0.42 to 13.96 ± 0.47%, 9.70 ±  to 13.00 ± 0.30 and 21.70 ± 0.59 to 30.40 ± 0.53% for the indigenous and Amo breed groups of cockerel, respectively. It was concluded that semen quality characteristics could be differed between genetically improved (Amo strain) and indigenous breed of cockerels.
Cytotoxicity, antioxidant and phytochemical screening of propolis extracts from four different Malaysian stingless bee species
Authors: Mat Nafi Nor Elani , Md Zin Nur Basyirah , Pauzi Norzilawati , Abdul Khadar Ammira Shafiqha , Anisava Aulia Rani , Mohd Badiazaman Ainur Awanis , Mohd Khamsah Suryati
Published: April 2020

Propolis is a plant-derived substance collected by stingless bee’s product from various sources, including plant resins with combination of bee’s saliva and wax. Propolis has been used to treat several diseases since ancient times and it is an important source of bioactive natural compound and drug derivatives. The aim of this study was to evaluate biological and chemical profiles of ethanolic extracts from propolis produced by Heterotrigona itama (HI), Geniotrigona thoracica (GT), Lepidotrigona terminate (LT), and Tretrigona apicalis (TA). Cytotoxicity activity was evaluated by using 3-(4,5-Dimethylthiazol-2-YI)-2,5-Diphenyltetrazolium Bromide (MTT) assay against three cancer cell lines. H. itama extracts showed the highest cytotoxicity effect with   of 5 µg/mL, 4 µg/mL and 8 µg/mL for MDA-MB-231, SK-UT-1 and HeLa, respectively. Other species only possessed moderate to weak cytotoxicity effect against tested cells. Phytochemical screening was carried out by thin layer chromatography (TLC) analysis and visualized by derivatives agents in order to detect the presence of terpenoids, steroids, saponins, essential oils and phenol. It  was found that H. itama (HI) possessed the highest antioxidant activity with the lowest  of 30 µg/mL with percetange of inhibition at 85.69 % evaluated by (2,2-diphenyl-1-picryl-hydrazyl-hydrate) DPPH scaveging assay. In conclusion, bee species was considered as important factor in selecting the quality of propolis. It was found that H. itama produced the most active extract compared to other species. The data obtained from this study would be the basis for further investigation on therapeutic application especially for cytotoxic activity, antioxidant and phytochemical screenings for four Malaysian stingless bees of propolis.
Phytochemical screening and antioxidant properties of stingless bee Geniotrigona thoracica propolis
Authors: Mohd Badiazaman Ainur Awanis , Md Zin Nur Basyirah , Annisava Aulia Rani , Mat Nafi Nor Elani , Mohd Khamsah Suryati
Published: April 2020

Propolis is a gum-like product that collected by bees from plants and it varies in colour range from light yellow to dark brown. The chemical composition of propolis depends on various factors such as vegetation, season and environmental conditions of the sample collection. The aim of the study was to determine the chemical profile and antioxidant properties of crude methanol extract of Geniotrigona thoracica propolis from five localities, namely Besut (BST), Dungun (DGN), Lundang (LDG), Tanah Merah (TM) and Gua Musang (GM). Phytochemical screening by thin layer chromatography (TLC) showed the presence of terpenoids, flavonoids, coumarins, essential oils and unsaturated and aromatic compounds. The extracts displayed different characteristics of chemical profile that varied from each other. The antioxidant properties of extracts were evaluated based on total phenolic content, total flavonoid content and 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical-scavenging activity. Propolis from Gua Musang (GM) exhibited the highest total phenolic content with 23.43 ± 0.50 mg GAE/g extract while propolis from Besut (BST) exhibited the highest total flavonoids content with 17.22 ± 0.16 mg QE/g extract and showed the lowest IC50 with 53 µg/mL for DPPH radical scavenging activities. As a result, Geniotrigona thoracica from Besut (BST) could be considered as a good source of antioxidant due to its antioxidant properties.
Antioxidant and antibacterial activities of Ischaemum indicum leaves extracted using different solvents
Authors: Auwaliyah Fithrotul , Rizqi Hamdan Dwi , Purnomo Adi Setyo , Fatmawati Sri
Published: April 2020

The aim of this study was to evaluate antioxidant and antibacterial activities of Ischaemum indicum leaves extracts based on different polarity solvents: water, methanol, ethyl acetate, dichloromethane, and n-hexane. The antioxidant activity was evaluated using ABTS and DPPH methods, while the antibacterial activity was determined by broth dilution method against Pseudomonas aeruginosa and Bacillus subtilis. The results showed that water and methanol extracts of I. indicum gave the highest antioxidant activity in ABTS assay with an IC50 73.80 and 46.32 µg/mL, respectively. On the other hand, The IC50 on DPPH assay for  water extracts was 117.51 µg/mL, this value was higher than that of methanol extract with no inhibition. Methanol and water extracts showed the antibacterial activity against B. subtilis with inhibition of 48.62 and 45.11%, whereas inhibition of P. aeruginosa were 31.95 and 30.31%, respectively. This study denoted that I. indicum is a new potential candidate as antioxidant source.
Yaw angle effect on the aerodynamic performance of hatchback vehicle fitted with wing spoiler
Authors: Chin Kwang-Yhee , Cheng See-Yuan , Mansor Shuhaimi
Published: April 2020

Research on spoiler available to date was mainly done to optimize the performance of spoiler in non-zero yaw condition. However, the effect of spoiler is most needed during cornering to ensure the stability of the vehicle. Therefore, this study aims to inspect the effect of yaw angles change on the aerodynamic performance of the NACA 0018 wing spoiler and the subsequent influence on the flow characteristics of the hatchback vehicle. Computational Fluid Dynamics (CFD) has been applied to model the flow. Comparison between numerically obtained results and experimental data was done to validate the CFD method. The findings show that both the drag coefficient, Cd, and lift coefficient, Cl have increased with increasing yaw angle. However, the spoiler has performed in favor of reducing the Cd and Cl even with increasing yaw angle. The averaged proportion contributions from the spoiler to the overall Cd and Cl are 2.7% and 4.1%, respectively. The other body parts that have contributed to the Cd and Cl reductions were the base and slant, and the roof.
Biodegradation of crude oil by Ralstonia pickettii under high salinity medium
Authors: Purnomo Adi Setyo , Rizqi Hamdan Dwi , Harmelia Lia , Anggraeni Silmi Diah , Melati Ranny Etna , Damayanti Zulfah Hernida , Shafwah Ova Mar’atus , Kusuma Fransisca Cahyaning
Published: April 2020

Bacterium Ralstonia pickettii has ability to survive and thrive in low nutrient condition as well as a capability to remediate some pollutants and using them as carbon and energy source. In this study, the ability of R. pickettii on biodegradation of crude oil under high salinity medium was investigated. R. pickettii was pre-incubated in nutrient broth (NB) medium and then, washed and transferred to artificial seawater medium. Crude oil was added to each culture and incubated for 7 and 14 days. The biodegradation of crude oil was analysed using Gas chromatography mass spectrometry (GC-MS). The result showed that R. pickettii had successfully degraded the crude oil in the high salinity artificial seawater. The incubation on 7 and 14 days did not show a significant effect on the number of the degraded compounds. The optimum recovery percent was obtained from the derivation of 2,6,10,14-tetramethyl hexadecane with the recovery percentage of 12.7% and 16.0% for 7 and 14 days respectively. This study indicates that R. picketti can be potentially used for bioremediation of crude oil under high salinity environments.
Phytochemical analysis and antioxidant activity of different plant parts of Pellacalyx axillaris
Authors: Ahmad Kuthi Najwa , Basar Norazah
Published: April 2020

Pellacalyx axillaris or locally known as ‘membuloh’ is a mangrove species belonging to the Rhizophoraceae family. Till date, there has been only one phytochemical study found on this particular plant species and that without any documentation on its biological activities. Therefore, the present work aimed to reveal the phytoconstituents and the antioxidant activity of different crude extracts from different plant parts of P. axillaris. Experimentally, three organic solvents of different polarities i.e. n-hexane, ethyl acetate and methanol were used to prepare the crude extracts from the dried leaves, twigs and barks of P. axillaris. The preliminary phytochemical screening of this species indicated the presence of terpenoids, phenolic compounds, tannins, flavonoids, alkaloids, anthraquinone glycosides and carbohydrates. The in vitro antioxidant activity of the species evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging assay, and ferric reducing antioxidant power (FRAP) suggested that the methanolic bark extract contained potential source of natural antioxidants. Further research into isolation of antioxidant compounds from this species is highly recommended.
Zeolite templated carbon: Preparation, characterization and performance as filler material in co-polyimide membranes for CO2/CH4 separation
Authors: Gunawan Triyanda , Romadiansyah Taufik Qodar , Wijiyanti Rika , Wan Salleh Wan Norharyati , Widiastuti Nurul
Published: April 2020

Zeolite templated carbon (ZTC), a structurally unique carbon material was used as new fillers for the preparation of composite polymeric membrane derived from BTDA-TDI/MDI (P84) co-polyimide. The thermal stability of membrane, the structure evolution, morphology and topology, as well as gas separation performance of modified membranes were investigated. Zeolite-Y, a hard template for ZTC, was synthesized via hydrothermal method. The ZTC was synthesized via impregnation of sucrose as carbon precursor into zeolite pore and followed by carbonization at 800°C. The zeolite template was removed through acid treatment to obtain ZTC, which was used as fillers for membrane preparation. The membrane was prepared using P84 co-polyimide as membrane precursor via phase inversion process. Synthesized materials were characterized using SEM, XRD, N2 adsorption-desorption isotherm and TEM. The thermal stability of membrane was improved by the addition of ZTC. As the result of ZTC loading into P84 co-polyimide membrane, the gas permeability of CO2 increased thirty-four times, as well as the CO2/CH4 selectivity boosted from 0.76 to 5.23.  The ordered pore structure in ZTC plays important role in increasing the permeability and selectivity performances of the P84 co-polyimide membrane.
In vitro cell viability of PHBV/PLGA nanofibrous membrane for tissue engineering
Authors: Hassan Mohd Izzat , Sultana Naznin
Published: April 2020

In recent decades, tissue engineering has emerged as an alternative solution to improve the quality of life for patients who suffer from diseases involving loss of tissues. The development of a biocompatible tissue engineering scaffold using nanofibrous membrane has garnered increasing interest in biomedical applications due to its similarity of structural property to the extracellular matrix, which is essential for cell growth. Thus, this study was conducted to fabricate a nanofibrous membrane with small diameter structure using a polymer blend of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(lactic-co-glycolic acid) (PLGA) and through the electrospinning technique, and to evaluate its biocompatibility with fibroblast cells. The nanofibrous structure was optimized using three different ratios (25:75; 50:50; 75:25) of PHBV/PLGA polymer. Characterization of the nanofibrous membrane was done using a scanning electron microscope (SEM), attenuated total reflection - Fourier transform infrared spectroscopy (ATR-FTIR), and water contact angle (WCA). Biocompatibility evaluation was done by culturing the nanofibrous membrane with human skin fibroblast cells (HSF), then measuring cell viability using MTT and live/dead assays. Results indicated that the nanofibrous membrane obtained a homogeneous morphology at 50:50 ratio with a fiber diameter range of 200 – 1000 nm, had a minimum contact angle of 106.90 ± 4.42°, and good cell viability with HSF. Analyses from the SEM analysis and live/dead assays showed that the cells had proliferated after 7 days. Findings from this study suggest that PHBV/PLGA nanofibrous membrane can be used as a biocompatible artificial scaffold in tissue engineering application.
Effect of graphene nanoplatelets on flame retardancy and corrosion resistance of epoxy nanocomposite coating
Authors: Kabeb Siti Maznah , Hassan Azman , Mohamad Zurina , Sharer Zalilah , Mokhtar Munirah , Ahmad Faiz
Published: April 2020

Various concentrations of graphene nanoplatelets (GNP) i.e. 0.2, 0.4, 0.6, 0.8 and 1.0 wt. % were incorporated into the epoxy resin by sonication technique and mechanical agitation process. Limiting oxygen index (LOI) test and thermogravimetric analysis (TGA) indicated that the presence of GNP greatly enhanced the flame retardancy properties of the epoxy coating. Salt spray results obtained suggested that the addition of GNP enhanced corrosion performance and reducing the water absorption in comparison with pristine epoxy coating. Adhesion (cross-cut test) revealed that the presence of GNP showed great adhesion to substrates. Incorporation of 0.8 wt. % GNP exhibited the superior anticorrosion performance, great adhesion to subtract, and the lowest water uptake among other samples.
Tetradentate phenolic Schiff base ligands derived from aromatic diamine and their nickel (II) complexes: Synthesis, characterization, and in vitro anticancer screening
Authors: Ahmad Shahrul Nizam , Bahron Hadariah , Tajuddin Amalina Mohd , Ramasamy Kalavathy
Published: April 2020

Two tetradentate phenolic Schiff base ligands namely 2,2'-((1E,1'E)-(1,2-phenylenebis(azanyl-ylidene))bis(methanylylidene))diphenol, L1H, 2,2'-((1E,1'E)-(1,2-phenylenebis(azanylylidene))bis-(methanylylidene))bis(4-fluorophenol), L1F and their new nickel(II) complexes were successfully synthesized, characterized and evaluated for their in vitro anticancer activities against human colon cancer cell lines, HCT116. The compounds were characterized using FT-IR, 1H and 13C NMR, UV-Visible, elemental analysis and melting point. The anticancer results revealed that the parent ligands were more active than their corresponding complexes with L1F being the most potent anticancer compound with IC50 of 2.8 mg/ml.
Texture Profile Analysis (TPA) of the jelly dessert prepared from halal gelatin extracted using High Pressure Processing (HPP)
Authors: Yusof Nurlina , Jaswir Irwandi , Jamal Parveen , Jami Mohammad Saedi
Published: April 2020

High Pressure Processing (HPP) is a novel extraction method. This technique increases the yield of gelatin and enhances its properties. In this study, the performance of the gelatin extracted from red tilapia fish skin treated with HPP was evaluated using the Texture Profile Analysis (TPA) method, in comparison with the commercial fish gelatin. Based on the Total Soluble Solid (TSS) results, the jelly prepared with HPP-treated gelatin has a longer shelf life. The sensory textures of the lychee jelly were described based on the force-time plot. The results showed that the hardness, adhesiveness, gumminess and chewiness of the jelly prepared using HPP-treated gelatin are higher compared with the commercial gelatin while the cohesiveness and the springiness are similar for both jellies. In conclusion, the jelly prepared using gelatin treated with HPP is preferable compared to the commercial gelatin because it is more rigid, firm and adhesive.
A Modeling Study of Discharging Li-O2 Batteries With Various Electrolyte Concentrations
Authors: Wang Fangzhou , Li Xianglin , Hao Xiaowen , Tan Jianyu
Published: April 2020

The mass transfer in the cathode electrode plays an important role in operating Li-O2 batteries. In this study, a two-dimensional, transient, and isothermal model is developed to investigate the mass transfer in discharging Li-O2 batteries. This model simulates the discharge performance of Li-O2 batteries with various electrolyte concentrations (0.1−1.0M) at various current densities (0.1, 0.3, and 0.5 mA/cm2). The O2 diffusivity and the ionic conductivity and diffusivity of Li+ are altered as the bis(trifluoromethane)sulfonimide lithium salt (LiTFSI) concentration in the electrolyte of tetraethylene glycol dimethyl ether (TEGDME) changes. The distributions of O2, Li+, and lithium peroxide (Li2O2) in the cathode electrode after discharge are calculated using this model. Modeling results show that when the concentration decreases from 0.5 to 0.25M, the discharge capacity of Li-O2 sharply drops at various current densities. The mass transfer of Li+ determines the discharge capacity of Li-O2 batteries with dilute electrolytes (≤0.25 M). In contrast, the O2 supply is dominant regarding the discharge capacity when the electrolyte concentration is larger than 0.5M. The highest discharge capacity (e.g., 6.09 mAh at 0.1 mA/cm2) is achieved using 0.5M electrolyte since it balances mass transfer of O2 and Li+.
Measurement of Natural Vibrations and Resonant Second Higher-Harmonics Due to a Fatigue Crack
Authors: Kanda Kosuke , Lin Shan
Published: April 2020

Nonlinear ultrasonic testing is considered a more promising technique for evaluating closed cracks than conventional ultrasonic testing. However, the mechanism of the generation of nonlinear ultrasonic waves has not been sufficiently explained. We first set up a system to measure the frequency–response characteristics of ultrasonic waves and experimentally investigated the mechanism of second higher-harmonic (HH) wave generation for a fatigue crack. Sweeping the frequencies of incident waves impinging on a fatigue crack introduced to a specimen, we obtained a frequency–response characteristic curve for the crack. From the curve, resonance phenomena resulting from local defect resonance were observed. We then measured the frequency response characteristics of second HH waves using the same system and consequently confirmed that second HH waves resonated when their frequencies corresponded to the eigenfrequencies of the crack. Finally, we theoretically showed that the resonant second HH waves were generated by local defect resonance and nonlinearity.
Assessment of Photovoltaic Capabilities in Urban Environments: A Case Study of Islamabad, Pakistan
Authors: Zubair Muhammad , Ghuffar Sajid , Shoaib Muhammad , Awan Ahmed Bilal , Bhatti Abdul Rauf
Published: April 2020

Photovoltaic (PV) estimation in an urban environment requires detection of rooftop area, design of PV system based on optimization on PV placement distance and the study of additional benefit of lower cooling load of building by shading provided by PV panels. The study is aimed at policymakers to introduce renewable energy policy toward net-zero energy buildings in urban areas. In this research, the capital city of Pakistan, Islamabad, is analyzed for rooftop PV capabilities using deep learning algorithms. The area of the rooftop is calculated by extracting buildings in high-resolution satellite imagery using a deep learning algorithm. The site location is analyzed for available solar energy resources. The distance between the rooftop-PV array is optimized based on self-shading losses, coefficient of performance, energy yield, net-zero energy analysis, and reduction of cooling load of the building provided by PV arrays as shading devices. The 40-km2 area of Islamabad considered in this research can generate 1038 GWh of solar energy annually from its 4.3-km2 rooftop area by installed capacity of 447 MW PV panels rows placed at 0.75 m apart. The electricity generated by Islamabad can curtail residential load from the national grid and form a near net-zero energy zone while the electrical energy from the grid can be provided to the industries to enhance the economy and reduce unemployment in Pakistan.
Numerical and Experimental Studies of Pendulum Dynamic Vibration Absorber for Structural Vibration
Authors: Ha Seon Il , Yoon Gil Ho
Published: April 2020

This research presents a pendulum dynamic vibration absorber (PDVA) consisting of a spring and a mass in order to attenuate structural vibrations at two frequencies of hosting structure. It is a convention to attach several dynamic absorbers to hosting structure for the sake of the attenuations of structural vibrations at multiple frequencies with enlarged bandwidth and often it increases the total mass and the installation cost. Therefore, the reduction of the number of vibration absorbers for multiple excitation frequencies is an important issue from an engineering point of view. To resolve these difficulties, this study proposes to adopt the vibration absorber framework of the spring-mass vibration as well as the pendulum vibration simultaneously with the present PDVA system. It is composed of a spring and a mass but being allowed to swing circumferentially, the structural vibrations at the two resonance frequencies, i.e., the square root of stiffness over mass and the square root of a length over gravidity, can be simultaneously attenuated. As the length of the spring of the present PDVA is varied, the effective ranges for the pendulum dynamic vibration absorber become widen. To prove the concept of the present PDVA, this research conducts several numerical simulations and experiments.
On the Characterization of Nonlinearities in Assembled Structures
Authors: Smith Scott A. , Brake Matthew R. W. , Schwingshackl Christoph W.
Published: April 2020

This work refines a recently formalized methodology proposed by D.J. Ewins consisting of ten steps for model validation of nonlinear structures. This work details, through a series of experimental studies, that many standard test setup assumptions that are made when performing dynamic testing are invalid and need to be evaluated for each structure. The invalidation of the standard assumptions is due to the presence of nonlinearities, both known and unrecognized in the system. Complicating measurements, many nonlinearities are currently characterized as constant properties instead of variables that exhibit dependency on system hysteresis and actuation amplitude. This study reviews current methods for characterizing nonlinearities and outlines gaps in the approaches. A brief update to the CONCERTO method, based on the accelerance of a system, is derived for characterizing a system’s nonlinearities. Finally, this study ends with an updated methodology for model validation and the ramifications for modeling assemblies with nonlinearities are discussed.
Contact Stress and Linearized Modal Predictions of As-Built Preloaded Assembly
Authors: Brink Adam R. , Kuether Robert J. , Fronk Matthew D. , Witt Bryan L. , Nation Brendan L.
Published: April 2020

The member stiffness and pressure distribution in a bolted joint is significantly influenced by the contact area of the mechanical interface under a prescribed preload force. This research explores the influence of as-built surface profiles for nominally flat interfaces of a C-Beam assembly with two well-defined contact regions. A high-fidelity finite element model is created such that the model uncertainty is minimized by updating and calibrating the piece parts prior to the preload assembly procedure. The model is then assembled and preloaded to evaluate the contact stresses and contact area for both nominally flat and perturbed non-flat surfaces based on three-dimensional surface topography measurements. The predicted pressures are validated with digitized pressure-sensitive film measurements. The high-fidelity modeling reveals how the compliance and thickness of the pressure-sensitive film alter the measured pressures, leading to incorrect evaluations of the stresses and contact area in the joint. The resulting low-level dynamic behavior of the preloaded assembly is shown to be sensitive to the true contact area by linearizing the nonlinear finite element model about the preloaded equilibrium and performing a computational modal analysis. The resonant frequencies are validated with experimental measurements to demonstrate the effect of the contact area on the modal characteristics of the bolted assembly. Vibration modes and loading patterns exhibit varying levels of sensitivity to the contact area in the joint, leading to an improved physical understanding of the influence of contact mechanics on the low-level linear vibration modes of jointed assemblies.