bluuebunny/crossref_metadata_2025 huggingface dataset:
Una mirada a la tercerización de Venezuela
Authors: Oberto Thania , Aranguren Williams
Published: March 2020

El presente trabajo busca dar una mirada a la tercerización en Venezuela y tiene como objetivo analizar la tercerización en el contexto legal venezolano. Para ello, es preciso identificar primero cuándo estamos en presencia de un contrato de trabajo y diferenciarlo de otros contratos civiles y mercantiles de prestación de servicios. Segundo, es preciso establecer cuándo existe simulación o fraude; vale decir, cuándo hay tercerización. Y, por último, es preciso examinar las relaciones triangulares de trabajo. Para lograr los objetivos propuestos se hizo una investigación documental y de nivel descriptivo, con énfasis en la normativa legal que regula la materia. Se concluye que el fenómeno de la tercerización en los términos de la legislación laboral implica siempre la precarización del empleo, porque quién busca evadir el cumplimiento de las obligaciones laborales genera la pérdida de derechos laborales para los trabajadores involucrados. Por ello, resulta sumamente importante, para alcanzar la justicia social, que el Estado busque eliminar los vacíos y vaguedades existentes en la normativa legal que regulan esta materia, con el fin de favorecer la labor interpretativa de los jueces en materia de tercerización y así evitar la evasión de las obligaciones laborales y, por ende, garantizar la protección legal de los trabajadores tercerizados.
OS OTIMISTAS VIVEM MAIS: UM ESTUDO RETÓRICO DA SELEÇÃO LEXICAL
Authors: Vescovi Jessica Paula
Published: March 2020

OS OTIMISTAS VIVEM MAIS: UM ESTUDO RETÓRICO DA SELEÇÃO LEXICALRESUMO: As escolhas das palavras dizem muito sobre o lugar ocupado por aquele que as escolhe. Partindo desta ideia, o presente estudo visa analisar quatro textos que divulgam o mesmo estudo, de diferentes esferas comunicativas, escritos em diferentes idiomas, publicados em revista científica, revista de circulação geral e revistas de divulgação científica, quanto ao léxico, à argumentação e à associação léxico-retórica, a partir dos pressupostos retóricos defendidos por Perelman e Tyteca, Dittrich (2008) e sociorretóricos (Swales).PALAVRAS-CHAVE: Seleção lexical, retórica.OPTIMISTS LIVE LONGER: A RHETORICAL STUDY OF LEXICAL SELECTIONABSTRACT: The words choice can say many things about the place where the author speaks from. From this idea, this study aims to analyze four different texts, from different social perspectives, in different idioms, published in scientific, general and scientific spreads magazine. This analyze will focus on lexical and rethorical perspective, in order to associate both of them from Perelman and Tyteca, Dittrich and Swales perspective.KEYWORDS: Lexical choices, rethoric. LOS OPTIMISTAS VIVEN MÁS: UN ESTUDIO RETÓRICO DE LA SELECCIÓN LEXICALRESUMEN: Las opciones de las palabras dicen mucho sobre el lugar ocupado por el que las escoge. A partir de esta idea, el presente estudio busca analizar cuatro textos que divulgan el mismo estudio, de diferentes esferas comunicativas, escritos en diferentes idiomas, publicados en revista científica, revista de circulación general y revistas de divulgación científica, en cuanto al léxico, a la argumentación ya la la asociación léxico-retórica, a partir de los presupuestos retóricos defendidos por Perelman y Tyteca, Dittrich (2008) y sociorretóricos (Swales).PALAVRAS CLAVE: Selección léxica, retórica.
Torsional Buckling of Thin-Walled Columns with Transverse Stiffeners: Analytical Studies
Authors: Hoang Trung , Ádány Sándor
Published: March 2020

In this paper the pure torsional buckling of thin-walled column members is investigated, with a special focus on the effect of transverse plate elements, such as end-plates or transverse stiffeners. The linear buckling problem is aimed to solve analytically, therefore the necessary (differential) equations are first established. For some simple problems, namely doubly-symmetric I-sections with pinned-pinned or clamped-clamped supports and with rectangular stiffeners or end-plates, closed formulae are derived to calculate the critical force. It is shown that the transverse elements have two effects: the direct effect is due to the deformation of the transverse elements, while the indirect effect is that the transverse elements modify the longitudinal distribution of the member’s displacements. It is also shown how the stiffener-to-member connection influences the results. The analytical solutions are discussed by several numerical examples: the results from the derived formulae are compared to results from shell finite element buckling analyses.
KEARIFAN LOKAL KAAGO-AGO DALAM BUDIDAYA TANAMAN JAGUNG DI KECAMATAN MALIGANO KABUPATEN MUNA
Authors: Isnian Sitti Nur , Musadar Musadar , Harmayani Harmayani
Published: March 2020

Penelitian ini berangkat dari fenomena petani jagung di Kecamatan Maligano Kabupaten Muna dalam menjalankan budidaya pertaniannya menggunakan kearifan lokal upacara kaago-ago, sehingga penelitian ini bertujuan untuk mengungkap kearifan lokal kaago-ago dalam budidaya tanaman jagung di kecamatan Maligano Kabupaten Muna.  Penelitian ini dilaksanakan pada bulan Oktober-November 2018. Penelitian bersifat kualitatif dengan melibatkan 17 informan yang terdiri dari kepala adat, petani, dan pemuka masyarakat.  Hasil penelitian menunjukkan kearifan lokal kaago-ago pada kegiatan penyiapan lahan dan panen meliputi upacara lengkap, pada penyiapan benih meliputi dokambae tanpa upacara, penanaman meliputi menutup mata gigi dirapatkan dan lafazd doa tanpa upacara, dan pada pemeliharaan tanaman tidak ada perlakuan. Melalui penelitian ini diharapkan wawasan masyarakat dapat terbuka, melihat kearifan lokal sebagai sebuah potensi dengan membuka diri terhadap inovasi baru, sehingga kearifan lokal masyarakat dapat menunjang usaha tani yang mereka jalani.
Isolasi dan Karakterisasi Enzim Selulase dari Keong Sawah Pila ampullaceal Menggunakan Substrat Serbuk Gergaji Kayu
Authors: Hamzah Hasty
Published: March 2020

Enzim selulase adalah enzim yang berperan dalam katalisis reaksi hidrolisis selulosa menjadi glukosa. Enzim ini dapat diisolasi dari keong sawah Pila ampullacea menggunakan substrat selulosa alami dari serbuk gergaji kayu.Tujuan penelitian ini adalah mengisolasi dan menentukan kondisi optimum selulase dari keong sawah. Penelitian diawali dengan persiapan substrat serbuk gergaji dengan cara delignifikasi menggunakan NaOH 2%. Selanjutnya mengisolasi enzim selulase dari hepatopankreas keong sawah melalui teknik destruksi, homogenisasi dan sentrifugasi. Penelitian dilanjutkan untuk memurnikan selulase melalui pengendapan protein selulase menggunakan amonium sulfat (NH4)2SO4 pada berbagai tingkat kejenuhan 10%, 20%, 30%, 40%, 60%, 80%. Pemurnian tahap berikutnya dilakukan dengan cara dialisis menggunakan membran selofan. Aktivitas selulase diperoleh dengan menghitung kadar glukosa sebagai produk hidrolisis dari substrat selulosa (serbuk gergaji) menggunakan metode Nelson-Somogy, sedangkan kadar protein ditentukan dengan metode Lowry dengan menggunakan bovine serum albumin (BSA) sebagai standar. Enzim selulase dari keong sawah mencapai aktivitas maksimum pada kondisi optimum: konsentrasi substrat (serbuk gergaji) 2% (b/v), pH 5,8, suhu 40 ᵒC, konsentrasi enzim 7,2 mg/mL. Kata Kunci: Selulase, keong sawah, Pila ampullacea, serbuk gergaji, isolasi, karakterisasi
Senyawa Steroid Spons Xestospongia sp. dari Perairan Sulawesi Tenggara
Authors: Sadarun Baru , Malaka Muhammad Hajrul , Wahyuni W , Sahidin S
Published: March 2020

Telah dilakukan isolasi dan identifikasi senyawa kimia spons Xestospongia sp. dari perairan Sulawesi Tenggara serta uji aktivitasnya sebagai antibakteri. Ekstrak spons diperoleh dengan teknik maserasi menggunakan pelarut metanol. Pemisahan senyawa kimia dari ekstrak tersebut dilakukan dengan teknik kromatografi kolom vakum (KCV), kromatografi radial (KR), dan kromatografi lapis tipis (KLT). Identifikasi isolat menggunakan spektroskopi infra merah serta spektroskopi NMR-1D (1H dan 13C-NMR). Bakteri uji menggunakan Escherichia coli ATCC 35218 dan Staphylococcus aureus ATCC 25923 dengan metode difusi cakram. Isolat diperoleh sebagai padatan berwarna putih, dan hasil analisis spektroskopi infra merah maupun NMR-1D (1H dan 13C-NMR) memperlihatkan bahwa isolat merupakan senyawa dengan kerangka steroid sarangosterol. Uji aktivitas senyawa isolat  menunjukkan tidak adanya aktivitas terhadap bakteri E. coli ATCC 35218 dan  S. aureus ATCC 25923.Kata kunci: Xestospongia, spons, isolasi, antibakteri, E. coli, S. aureus
Optimasi Formula Gel Serbuk Getah Ashitaba (Angelica keiskei Koidzumi) dan Uji Aktivitas Terhadap Lama Penyembuhan Luka Eksisi pada Kelinci
Authors: Ittiqo Dzun Haryadi , Wahid Abdul Rahman
Published: March 2020

Luka eksisi adalah luka yang diakibatkan terpotongnya jaringan oleh goresan benda tajam. Senyawa golongan flavonoid telah dibuktikan secara pre klinis bisa mempercepat penyembuhan luka. Ashitaba mengandung senyawa golongan flavonoid. Sehingga diperkirakan memiliki potensi sebagai obat penyembuh luka. Penelitian ini merupakan penelitian eksperimental, getah ashitaba dibuat sediaan serbuk kering. Optimasi formula gel serbuk getah ashitaba menggunkan metode D-optimal design dengan Software Design Exspert versi 7.1.5. Komponen yang dioptimasi adalah formula standar gel basis natrium karboksimetil selulosa (Na-CMC) dan propilenglikol, respon yang dinilai adalah daya lekat, daya sebar dan pH. Formula optimum yang didapatkan diuji stabilitas. Selanjutnya dilakukan uji efektivitas formula optimum gel terhadap lama penyembuhan luka eksisi pada kelinci. Hewan uji dibagi dalam tiga kelompok penelitian yaitu kelompok kontrol negatif (basis gel), kontrol positif (betadin salap 10%) dan perlakuan menggunakan formula optimum gel serbuk getah ashitaba. Punggung kelinci dibuat luka eksisi sepanjang 3 cm, luka diolesi sampel uji sebanyak tiga kali sehari selama 7 hari. Pengamatan dilakukan dengan mengukur panjang luka selama perlakuan. Data diuji statistik dengan metode ANOVA dilanjutkan dengan uji LSD (Last significant different). Berdasarkan hasil penelitian, kombinasi CMC-Na dan propilenglikol mempengaruhi pH, daya sebar dan daya lekat. Hasil penelitian menunjukkan porsentase formula optimum bahan teroptimasi gel serbuk getah ashitaba yang dihasilkan untuk CMC-Na dan Propilenglikol masing-masing adalah 4,617% dan 10,383% dengan parameter nilai mutu fisik untuk pH 6,08, daya sebar 5,85 cm2, daya lekat 90,44detik. Gel menunjukkan stabiilitas selama proses penyimpanan serta berpotensi sebagai alternatif obat luka eksisiKata kunci: gel, getah ashitaba, luka eksisi, flavonoid
In the Era of Computers, Internet and Multimedia, are we still Teaching Composers to become Chapel-Masters?
Authors: De Souza Rodolfo Coelho
Published: March 2020

The ongoing paradigm shift from traditional methods of teaching music composition towards new approaches based on computer technology for sound production is the main focus of the article. The paper reviews the evolution of teaching methods throughout the Classical, Romantic and Modern periods, demonstrating how certain standard practices from former ages, based on the professional profile of the Chapel-Master, become theoretical golden principles for subsequent periods. After the French Revolution the traditional method of individual practical exchange between master and disciple was upgraded at the Conservatory. Classes for groups of students required a new approach based on theory abstraction. Although none of these teaching methods have been abandoned up today, a new paradigm appears when the tools of computer technology became widespread. An unpredictable equilibrium between the traditional methods and the new techniques of computer-assisted or computer-generated music composition tends to emerge.
Impact of Growth Stage and Biomass Fractions on Cannabinoid Content and Yield of Different Hemp (Cannabis sativa L.) Genotypes
Authors: Burgel Lisa , Hartung Jens , Pflugfelder Annegret , Graeff-Hönninger Simone
Published: March 2020

The medicinal use of cannabinoids renewed the interest in industrial hemp (Cannabis sativa L.). The aim of this study was to evaluate the impact of growth stage and biomass fractions of seven industrial hemp genotypes. The study focused on biomass yield, content of cannabidiolic acid/cannabidiol (CBDA/CBD), cannabigerolic acid/cannabigerol (CBGA/CBG), and tetrahydrocannabinolic acid (THCA). The experiment was conducted in 2017 and 2018. The biomass samples were taken at the vegetative (S1), bud (S2), full-flowering (S3) and seed maturity stage (S4). Plants were fractionated into inflorescence, upper and lower leaves. The average inflorescence dry yield of genotypes Futura75, Fédora17, Félina32 and Ferimon ranged between 257.28 g m−2 to 442.00 g m−2, resulting in a maximum yield of CBDA at S4, with 4568.26 mg m−2, 6011.20 mg m−2, 4975.60 mg m−2 and 1929.60 mg m−2, respectively. CBGA was exclusively found in genotype Santhica27, with a maximum CBGA yield of 5721.77 mg m−2 in inflorescence at growth stage S4 and a dry weight yield of 408.99 g m−2. Although these industrial hemp genotypes are mainly cultivated for fibre and seed production, however, cannabinoids offer an additional value. For an optimized harvest result, yield of extractable material and overall yield of cannabinoids must be considered.
Impact of Strain Competition on Bacterial Resistance in Immunocompromised Populations
Authors: DeNegre Ashley A. , Myers Kellen , Fefferman Nina H.
Published: March 2020

Despite the risk of emerging drug resistance that occurs with the frequent use of antimicrobial agents, targeted and prophylactic antibiotics have been considered crucial to opportunistic infection management among the HIV/AIDS-immunocompromised. As we recently demonstrated, the disrupted selective pressures that occur in AIDS-prevalent host populations increase the probability of novel emergence. This effect is concerning, given that bacterial strains unresponsive to first-line antibiotics can be particularly dangerous to hosts whose immune response is insufficient to fight infection in the absence of antibiotic support. While greater host susceptibility within a highly immunocompromised population may offer a fitness advantage to drug-resistant bacterial strains, this advantage could be mitigated by increased morbidity and mortality among the AIDS-immunocompromised. Using a Susceptible-Exposed-Infectious-Recovered (SEIR) epidemiological model parameterized to reflect conditions in an AIDS-prevalent host population, we examine the evolutionary relationship between drug-sensitive and -resistant strains of Mycobacterium tuberculosis. We explore this relationship when the fitness of the resistant strain is varied relative to that of the sensitive strain to investigate the likely long-term multi-strain dynamics of the AIDS-mediated increased emergence of drug resistance.
MicroRNAs in Small Extracellular Vesicles Indicate Successful Embryo Implantation during Early Pregnancy
Authors: Tan Qiang , Shi Shuang , Liang Jingjie , Zhang Xiaowei , Cao Dingren , Wang Zhengguang
Published: March 2020

Synchronous communication between the developing embryo and the receptive endometrium is crucial for embryo implantation. Thus, uterine receptivity evaluation is vital in managing recurrent implantation failure (RIF). The potential roles of small extracellular vesicle (sEV) miRNAs in pregnancy have been widely studied. However, the systematic study of sEVs derived from endometrium and its cargos during the implantation stage have not yet been reported. In this study, we isolated endometrium-derived sEVs from the mouse endometrium on D2 (pre-receptive phase), D4 (receptive phase), and D5 (implantation) of pregnancy. Herein, we reveal that multivesicular bodies (MVBs) in the endometrium increase in number during the window of implantation (WOI). Moreover, our findings indicate that CD63, a well-known sEV marker, is expressed in the luminal and glandular epithelium of mouse endometrium. The sEV miRNA expression profiles indicated that miR-34c-5p, miR-210, miR-369-5p, miR-30b, and miR-582-5p are enriched during WOI. Further, we integrated the RIF’s database analysis results and found out that miR-34c-5p regulates growth arrest specific 1 (GAS1) for normal embryo implantation. Notably, miR-34c-5p is downregulated during implantation but upregulated in sEVs. An implication of this is the possibility that sEVs miR-34c-5p could be used to evaluate uterine states. In conclusion, these findings suggest that the endometrium derived-sEV miRNAs are potential biomarkers in determining the appropriate period for embryo implantation. This study also has several important implications for future practice, including therapy of infertility.
Sunscreen Boosting Effect by Solid Lipid Nanoparticles-Loaded Fucoxanthin Formulation
Authors: Lee Yong-Jik , Nam Gae-Won
Published: March 2020

Fucoxanthin is a bioactive compound that is a kind of natural carotenoid. Fucoxanthin is known to protect against UV-B-induced cell damage in hairless mice, even though it is physiochemically unstable to heat and acid due to its polyunsaturated structure, indicating that fucoxanthin possesses a low bioavailability, and this disadvantage limits its application in the cosmetic industry. Solid lipid nanoparticle (SLN) systems are known to be suitable as carriers for sunscreen agents. In this research work, the sunscreen-boosting effect of SLN, as a deliverer of functional ingredient, especially fucoxanthin, has been developed and evaluated by comparing the sunburn protection factors (SPF) of macroemulsion (cream and lotion type) and an SLN formula containing various kinds of sunscreen agents, respectively. Several results such as stability test, particle size, DSC analysis, and X-ray analysis show that the SLN formula loading fucoxanthin has the possibility of being a stable and high-functioning ingredient delivery system. Moreover, the SLN formula has shown a higher SPF value than others, meaning that the SLN formula exhibits a good sunscreen-boosting effect. This study indicates that the use of SLN as a carrier enhanced the bioavailability of fucoxanthin and shows that SLN could be a promising carrier for the production of sunscreen products by allowing the scaling-up of production.
A Robust, Low-Cost and Secure Authentication Scheme for IoT Applications
Authors: Mahmod Md Jubayer al , Guin Ujjwal
Published: March 2020

The edge devices connected to the Internet of Things (IoT) infrastructures are increasingly susceptible to piracy. These pirated edge devices pose a serious threat to security, as an adversary can get access to the private network through these non-authentic devices. It is necessary to authenticate an edge device over an unsecured channel to safeguard the network from being infiltrated through these fake devices. The implementation of security features demands extensive computational power and a large hardware/software overhead, both of which are difficult to satisfy because of inherent resource limitation in the IoT edge devices. This paper presents a low-cost authentication protocol for IoT edge devices that exploits power-up states of built-in SRAM for device fingerprint generations. Unclonable ID generated from the on-chip SRAM could be unreliable, and to circumvent this issue, we propose a novel ID matching scheme that alleviates the need for enhancing the reliability of the IDs generated from on-chip SRAMs. Security and different attack analysis show that the probability of impersonating an edge device by an adversary is insignificant. The protocol is implemented using a commercial microcontroller, which requires a small code overhead. However, no modification of device hardware is necessary.
Two Heads Are Better Than One—Entrepreneurial Continuous Learning through Massive Open Online Courses
Authors: Żur Agnieszka
Published: March 2020

Globalisation and digital technology have changed the means and mechanisms of knowledge acquisition. The rapidly expanding open-access online resources and various digital learning platforms present new opportunities in the area of continuous entrepreneurial learning, including that of corporate employees. This paper draws on knowledge spillover theory in order to explore the potential of Massive Open Online Courses (MOOCs) as enablers of knowledge exchange, consolidation and new knowledge creation through connecting geographically and institutionally distant actors. The research design is based on a qualitative interpretative approach exploiting a triangulation of methods by using sets of quantitative data collected from MOOC participants, five focus group interviews and text content of online course discussion groups. This study contributes to our understanding of how digital technologies enable entrepreneurial learning on a massive scale. It identifies three factors which can trigger intense horizontal knowledge spillovers on a massive scale: (i) participants’ common interests and aspirations, (ii) induced mobilisation, and (iii) participants’ optional anonymity. Additionally, the findings of this study provide useful information for potential MOOC creators regarding the design and delivery of MOOCs targeting a high density of participant interactions.
Ultrathin Film PtxPd(1-x) Alloy Catalysts for Formic Acid Oxidation Synthesized by Surface Limited Redox Replacement of Underpotentially Deposited H Monolayer
Authors: Achari Innocent , Dimitrov Nikolay
Published: March 2020

This work emphasizes the development of a green synthetic approach for growing ultrathin film PtxPd(1-x) alloy catalysts for formic acid oxidation (FAO) by surface limited redox replacement of underpotentially deposited H sacrificial layer. Up to three-monolayers-thick PtxPd(1-x) films with different composition are generated on Au electrodes and characterized for composition and surface roughness using XPS and electrochemical methods, respectively. XPS results show close correlation between solution molar ratio and atomic composition, with slightly higher Pt fraction in the deposited films. The accordingly deposited Pt42Pd58 films demonstrated remarkable specific and mass activities of up to 35 mAcm−2 and 45 Amg−1 respectively, lasting for more than 1500 cycles in FAO tests. This performance, found to be better twice or more than that of pure Pt counterparts, renders the Pt42Pd58 films comparable with the frontrunner FAO catalysts. In addition, the best alloy catalyst establishes a nearly hysteresis-free FAO CV curve a lot earlier than its Pt counterpart and thus supports the direct FAO pathway for longer. Overall, the combination of high Pd activity and CO tolerance with the remarkable Pt stability results in highly active and durable FAO catalysts. Finally, this facile and cost-effective synthetic approach allows for scaling the catalyst production and is thus appropriate for foreseeable commercialization.
Effects of Flow Rate on Mesenchymal Stem Cell Oxygen Consumption Rates in 3D Bone-Tissue-Engineered Constructs Cultured in Perfusion Bioreactor Systems
Authors: Felder Michael L. , Simmons Aaron D. , Shambaugh Robert L. , Sikavitsas Vassilios I.
Published: March 2020

Bone grafts represent a multibillion-dollar industry, with over a million grafts occurring each year. Common graft types are associated with issues such as donor site morbidity in autologous grafts and immunological response in allogenic grafts. Bone-tissue-engineered constructs are a logical approach to combat the issues commonly encountered with these bone grafting techniques. When creating bone-tissue-engineered constructs, monitoring systems are required to determine construct characteristics, such as cellularity and cell type. This study aims to expand on the current predictive metrics for these characteristics, specifically analyzing the effects of media flow rate on oxygen uptake rates (OURs) of mesenchymal stem cells seeded on poly(L-lactic acid) (PLLA) scaffolds cultured in a flow perfusion bioreactor. To do this, oxygen consumption rates were measured for cell/scaffold constructs at varying flow rates ranging from 150 to 750 microliters per minute. Residence time analyses were performed for this bioreactor at these flow rates. Average observed oxygen uptake rates of stem cells in perfusion bioreactors were shown to increase with increased oxygen availability at higher flow rates. The residence time analysis helped identify potential pitfalls in current bioreactor designs, such as the presence of channeling. Furthermore, this analysis shows that oxygen uptake rates have a strong linear correlation with residence times of media in the bioreactor setup, where cells were seen to exhibit a maximum oxygen uptake rate of 3 picomoles O2/hr/cell.
Comparison of Root Surface Wear and Roughness Resulted from Different Ultrasonic Scalers and Polishing Devices Applied on Human Teeth: An In-Vitro Study
Authors: Mahiroglu Muhammed Bedir , Kahramanoglu Erkut , Ay Mustafa , Kuru Leyla , Agrali Omer Birkan
Published: March 2020

The aim of the present study was to compare the root surface wear and roughness, resulted from the professional dental hygiene instruments, including ultrasonic dental scalers, rubber prophy cups, and nylon bristle brushes, on the extracted human mandibular incisor teeth. Teeth (n = 80) were randomly assigned into eight groups according to the applied scaler type (Ma = Magnetostrictive, Pi = Piezoelectric), degree of power (M = Medium, F = Full), and angulation (0° and 45°). In the second stage, the specimens (n = 40) were further divided into two groups according to the applied polishing device (nylon bristle brush or rubber prophy cup). Laser scanner and contact profilometer devices were used for the surface analysis. Both ultrasonic instruments tested in our study produced rougher surfaces when full power was used at a 0° angle (p < 0.01). The highest wear (0.82 ± 0.07 mm3) and roughness values (0.30 ± 0.01 µm) were detected in the PiF0 group. Polishing performed with a rubber prophy cup resulted in almost twice the wear as well as a smoother surface when compared to polishing performed with a nylon bristle brush (p < 0.001). Variations in the application parameters of ultrasonic scalers and the type of polishing instrument might lead to significantly different root-surface characteristics.
Calculation Methods of Icebreaking Capability for a Double-Acting Polar Ship
Authors: Zhou Li , Diao Feng , Song Ming , Han Yue , Ding Shifeng
Published: March 2020

As a key parameter, icebreaking capability is often used to judge whether a polar ship could navigate in level ice at a certain speed. This paper presents two methods to calculate icebreaking capability. The first one is a static method based on the estimation of ice resistance under different ice thicknesses and ship speeds. The second is a dynamic method that involves solving the equation of motion. A series of model tests with a double-acting icebreaking tanker were also carried out in the ice basin of the Krylov State Research Center to measure ice resistances. The simulated ice resistances were compared with model tests results for both ahead and astern running operations. The calculated icebreaking capability based on static and dynamic methods was validated with the model test result. A good agreement was achieved between measurement and simulation. The discrepancy between the model test result and the result simulated by the static or dynamic method was minor.
A Preliminary Study on an Alternative Ship Propulsion System Fueled by Ammonia: Environmental and Economic Assessments
Authors: Kim Kyunghwa , Roh Gilltae , Kim Wook , Chun Kangwoo
Published: March 2020

The shipping industry is becoming increasingly aware of its environmental responsibilities in the long-term. In 2018, the International Maritime Organization (IMO) pledged to reduce greenhouse gas (GHG) emissions by at least 50% by the year 2050 as compared with a baseline value from 2008. Ammonia has been regarded as one of the potential carbon-free fuels for ships based on these environmental issues. In this paper, we propose four propulsion systems for a 2500 Twenty-foot Equivalent Unit (TEU) container feeder ship. All of the proposed systems are fueled by ammonia; however, different power systems are used: main engine, generators, polymer electrolyte membrane fuel cell (PEMFC), and solid oxide fuel cell (SOFC). Further, these systems are compared to the conventional main engine propulsion system that is fueled by heavy fuel oil, with a focus on the economic and environmental perspectives. By comparing the conventional and proposed systems, it is shown that ammonia can be a carbon-free fuel for ships. Moreover, among the proposed systems, the SOFC power system is the most eco-friendly alternative (up to 92.1%), even though it requires a high lifecycle cost than the others. Although this study has some limitations and assumptions, the results indicate a meaningful approach toward solving GHG problems in the maritime industry.
Symmetric Conformable Fractional Derivative of Complex Variables
Authors: Ibrahim Rabha W. , Elobaid Rafida M. , Obaiys Suzan J.
Published: March 2020

It is well known that the conformable and the symmetric differential operators have formulas in terms of the first derivative. In this document, we combine the two definitions to get the symmetric conformable derivative operator (SCDO). The purpose of this effort is to provide a study of SCDO connected with the geometric function theory. These differential operators indicate a generalization of well known differential operator including the Sàlàgean differential operator. Our contribution is to impose two classes of symmetric differential operators in the open unit disk and to describe the further development of these operators by introducing convex linear symmetric operators. In addition, by acting these SCDOs on the class of univalent functions, we display a set of sub-classes of analytic functions having geometric representation, such as starlikeness and convexity properties. Investigations in this direction lead to some applications in the univalent function theory of well known formulas, by defining and studying some sub-classes of analytic functions type Janowski function and convolution structures. Moreover, by using the SCDO, we introduce a generalized class of Briot–Bouquet differential equations to introduce, what is called the symmetric conformable Briot–Bouquet differential equations. We shall show that the upper bound of this class is symmetric in the open unit disk.
Improved Initialization of the EM Algorithm for Mixture Model Parameter Estimation
Authors: Panić Branislav , Klemenc Jernej , Nagode Marko
Published: March 2020

A commonly used tool for estimating the parameters of a mixture model is the Expectation–Maximization (EM) algorithm, which is an iterative procedure that can serve as a maximum-likelihood estimator. The EM algorithm has well-documented drawbacks, such as the need for good initial values and the possibility of being trapped in local optima. Nevertheless, because of its appealing properties, EM plays an important role in estimating the parameters of mixture models. To overcome these initialization problems with EM, in this paper, we propose the Rough-Enhanced-Bayes mixture estimation (REBMIX) algorithm as a more effective initialization algorithm. Three different strategies are derived for dealing with the unknown number of components in the mixture model. These strategies are thoroughly tested on artificial datasets, density–estimation datasets and image–segmentation problems and compared with state-of-the-art initialization methods for the EM. Our proposal shows promising results in terms of clustering and density-estimation performance as well as in terms of computational efficiency. All the improvements are implemented in the rebmix R package.
Special Functions of Mathematical Physics: A Unified Lagrangian Formalism
Authors: Musielak Zdzislaw E. , Davachi Niyousha , Rosario-Franco Marialis
Published: March 2020

Lagrangian formalism is established for differential equations with special functions of mathematical physics as solutions. Formalism is based on either standard or non-standard Lagrangians. This work shows that the procedure of deriving the standard Lagrangians leads to Lagrangians for which the Euler–Lagrange equation vanishes identically, and that only some of these Lagrangians become the null Lagrangians with the well-defined gauge functions. It is also demonstrated that the non-standard Lagrangians require that the Euler–Lagrange equations are amended by the auxiliary conditions, which is a new phenomenon in the calculus of variations. The existence of the auxiliary conditions has profound implications on the validity of the Helmholtz conditions. The obtained results are used to derive the Lagrangians for the Airy, Bessel, Legendre and Hermite equations. The presented examples clearly demonstrate that the developed Lagrangian formalism is applicable to all considered differential equations, including the Airy (and other similar) equations, and that the regular and modified Bessel equations are the only ones with the gauge functions. Possible implications of the existence of the gauge functions for these equations are discussed.
Effect of Thermal Drying and Chemical Treatments with Wastes on Microbiological Contamination Indicators in Sewage Sludge
Authors: F. Santos Andreia , P. Santos Cátia , M. Matos Ana , Cardoso Olga , J. Quina Margarida
Published: March 2020

This work aims to evaluate the microbiological contamination of sewage sludge (SS) collected in urban wastewater treatment plants (WWTP) from Portugal. Two types of SS were considered: urban mixed (UM) and from anaerobic digestion (AD). The two types of samples were characterized in relation to the main physical and chemical parameters, as well as the microbiological contamination (Escherichia coli and Salmonella spp). Then, sanitation tests were conducted through thermal drying and chemical treatments. Towards a circular economy, industrial alkaline wastes (green liquor dregs - GLD, lime mud, coal fly ash, eggshell) were tested as alternatives to lime. Only six out of nineteen samples complied with the legal limits for both microorganisms. However, drying at 130 °C sanitized selected samples below the E. coli limit, regardless of the initial moisture or contamination. Additionally, CaO (obtained from eggshell) led to the complete elimination of E. coli at any dosage studied (0.05–0.15 g/g SSwet basis). GLD evidenced the ability to reduce E. coli contamination at room temperature, but not enough to comply with the legal limit. In general, this work highlights the need to sanitize the SS before its application to the soil, and the positive role of some wastes on this goal.
Flexible and Reusable Ag Coated TiO2 Nanotube Arrays for Highly Sensitive SERS Detection of Formaldehyde
Authors: Zhu Tong , Wang Hang , Zang Libin , Jin Sila , Guo Shuang , Park Eungyeong , Mao Zhu , Jung Young Mee
Published: March 2020

Quantitative analysis of formaldehyde (HCHO, FA), especially at low levels, in various environmental media is of great importance for assessing related environmental and human health risks. A highly efficient and convenient FA detection method based on surface-enhanced Raman spectroscopy (SERS) technology has been developed. This SERS-based method employs a reusable and soft silver-coated TiO2 nanotube array (TNA) material, such as an SERS substrate, which can be used as both a sensing platform and a degradation platform. The Ag-coated TNA exhibits superior detection sensitivity with high reproducibility and stability compared with other SERS substrates. The detection of FA is achieved using the well-known redox reaction of FA with 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (AHMT) at room temperature. The limit of detection (LOD) for FA is 1.21 × 10−7 M. In addition, the stable catalytic performance of the array allows the degradation and cleaning of the AHMT-FA products adsorbed on the array surface under ultraviolet irradiation, making this material recyclable. This SERS platform displays a real-time monitoring platform that combines the detection and degradation of FA.
Evaluation of Organo [18F]Fluorosilicon Tetrazine as a Prosthetic Group for the Synthesis of PET Radiotracers
Authors: Otaru Sofia , Imlimthan Surachet , Sarparanta Mirkka , Helariutta Kerttuli , Wähälä Kristiina , Airaksinen Anu
Published: March 2020

Fluorine-18 is the most widely used positron emission tomography (PET) radionuclide currently in clinical application, due to its optimal nuclear properties. The synthesis of 18F-labeled radiotracers often requires harsh reaction conditions, limiting the use of sensitive bio- and macromolecules as precursors for direct radiolabeling with fluorine-18. We aimed to develop a milder and efficient in vitro and in vivo labeling method for trans-cyclooctene (TCO) functionalized proteins, through the bioorthogonal inverse-electron demand Diels-Alder (IEDDA) reaction with fluorine-18 radiolabeled tetrazine ([18F]SiFA-Tz). Here, we used TCO-modified bovine serum albumin (BSA) as the model protein, and isotopic exchange (IE) (19F/18F) chemistry as the labeling strategy. The radiolabeling of albumin-TCO with [18F]SiFA-Tz ([18F]6), providing [18F]fluoroalbumin ([18F]10) in high radiochemical yield (99.1 ± 0.2%, n = 3) and a molar activity (MA) of 1.1 GBq/µmol, confirmed the applicability of [18F]6 as a quick in vitro fluorination reagent for the TCO functionalized proteins. While the biological evaluation of [18F]6 demonstrated defluorination in vivo, limiting the utility for pretargeted applications, the in vivo stability of the radiotracer was dramatically improved when [18F]6 was used for the radiolabeling of albumin-TCO ([18F]10) in vitro, prior to administration. Due to the detected defluorination in vivo, structural optimization of the prosthetic group for improved stability is needed before further biological studies and application of pretargeted PET imaging.
Blue Emitting Star-Shaped and Octasilsesquioxane-Based Polyanions Bearing Boron Clusters. Photophysical and Thermal Properties
Authors: Cabrera-González Justo , Chaari Mahdi , Teixidor Francesc , Viñas Clara , Núñez Rosario
Published: March 2020

High boron content systems were prepared by the peripheral functionalisation of 1,3,5-triphenylbenzene (TPB) and octavinylsilsesquioxane (OVS) with two different anionic boron clusters: closo-dodecaborate (B12) and cobaltabisdicarbollide (COSAN). TPB was successfully decorated with three cluster units by an oxonium ring-opening reaction, while OVS was bonded to eight clusters by catalysed metathesis cross-coupling. The resulting compounds were spectroscopically characterised, and their solution-state photophysical properties analysed. For TPB, the presence of COSAN dramatically quenches the fluorescence emission (λem = 369 nm; ΦF = 0.8%), while B12-substituted TPB shows an appreciable emission efficiency (λem = 394 nm; ΦF = 12.8%). For octasilsesquioxanes, the presence of either COSAN or B12 seems to be responsible for ∼80 nm bathochromic shift with respect to the core emission, but both cases show low emission fluorescence (ΦF = 1.4–1.8%). In addition, a remarkable improvement of the thermal stability of OVS was observed after its functionalisation with these boron clusters.
Inducing Intermediates in Biotransformation of Natural Polyacetylene and A Novel Spiro-γ-Lactone from Red Ginseng by Solid Co-Culture of Two Gut Chaetomium globosum and The Potential Bioactivity Modification by Oxidative Metabolism
Authors: Wang Bang-Yan , Zhu Chen-Hao , Yang Xue-Qiong , Hu Ming , Xu Ting-Ting , Wang Xue-Yin , Yang Shuang , Yang Ya-Bin , Ding Zhong-Tao
Published: March 2020

The ω-hydroxyl-panaxytriol (1) and ω-hydroxyl-dihydropanaxytriol (2)—are rare examples of polyacetylene metabolism by microbial transformation, and these new metabolites (1, 2) from fermented red ginseng (FRG) by solid co-culture induction of two Chaetomium globosum should be the intermediates of biotransformation of panaxylactone (metabolite A). The metabolic pathway of panaxylactone was also exhibited. The ingredients of red ginseng (RG) also induced the production of rare 6/5/5 tricyclic ring spiro-γ-lactone skeleton (3). The ω-hydroxylation of new intermediates (1, 2) decreases cytotoxicity and antifungal activity against C. globosum compared with that of its bioprecursor panaxytriol. Additionally, compounds 1 and 2 indicated obvious inhibition against nitric oxide (NO) production, with ratios of 44.80 ± 1.37 and 23.10 ± 1.00% at 50 μM. 1 has an equivalent inhibition of NO production compared with the positive drug. So, the microbial biotransformation that occurred in FRG fermented by gut C. globosum can change the original bioactivity of polyacetylene, which gave a basis about the metabolic modification of red ginseng by intestinal fungus fermentation.
An Overview of Self-Consistent Field Calculations Within Finite Basis Sets
Authors: Lehtola Susi , Blockhuys Frank , Van Alsenoy Christian
Published: March 2020

A uniform derivation of the self-consistent field equations in a finite basis set is presented. Both restricted and unrestricted Hartree–Fock (HF) theory as well as various density functional approximations are considered. The unitary invariance of the HF and density functional models is discussed, paving the way for the use of localized molecular orbitals. The self-consistent field equations are derived in a non-orthogonal basis set, and their solution is discussed also in the presence of linear dependencies in the basis. It is argued why iterative diagonalization of the Kohn–Sham–Fock matrix leads to the minimization of the total energy. Alternative methods for the solution of the self-consistent field equations via direct minimization as well as stability analysis are briefly discussed. Explicit expressions are given for the contributions to the Kohn–Sham–Fock matrix up to meta-GGA functionals. Range-separated hybrids and non-local correlation functionals are summarily reviewed.
Investigation of a Medical Plant for Hepatic Diseases with Secoiridoids Using HPLC and FT-IR Spectroscopy for a Case of Gentiana rigescens
Authors: Yang Yuangui , Zhao Yanli , Zuo Zhitian , Zhang Ji , Shi Yao , Wang Yuanzhong
Published: March 2020

Secoiridoids could be used as a potential new drug for the treatment of hepatic disease. The content of secoiridoids of G. rigescens varied in different geographical origins and parts. In this study, a total of 783 samples collected from different parts of G. rigescens in Yunnan, Sichuan, and Guizhou Provinces. The content of secoiridoids including gentiopicroside, swertiamarin, and sweroside were determined by using HPLC and analyzed by one-way analysis of variance. Two selected variables including direct selected and variable importance in projection combined with partial least squares regression have been used to establish a method for the determination of secoiridoids using FT-IR spectroscopy. In addition, different pretreatments including multiplicative scatter correction (MSC), standard normal variate (SNV), first derivative and second derivative (SD), and orthogonal signal correction (OSC) were compared. The results indicated that the sample (root, stem, and leaf) with total secoiridoids, gentiopicroside, swertiamarin, and sweroside from west Yunnan had higher content than samples from the other regions. The sample from Baoshan had more total secoiridoids than other samples for the whole medicinal plant. The best performance using FT-IR for the total secoiridoid was with the direct selected variable method involving pretreatment of MSC+OSC+SD in the root and stem, while in leaf, of the best method involved using original data with MSC+OSC+SD. This method could be used to determine the bioactive compounds quickly for herbal medicines.
An Enzymatic Flow-Based Preparative Route to Vidarabine
Authors: Tamborini Lucia , Previtali Clelia , Annunziata Francesca , Bavaro Teodora , Terreni Marco , Calleri Enrica , Rinaldi Francesca , Pinto Andrea , Speranza Giovanna , Ubiali Daniela , Conti Paola
Published: March 2020

The bi-enzymatic synthesis of the antiviral drug vidarabine (arabinosyladenine, ara-A), catalyzed by uridine phosphorylase from Clostridium perfringens (CpUP) and a purine nucleoside phosphorylase from Aeromonas hydrophila (AhPNP), was re-designed under continuous-flow conditions. Glyoxyl–agarose and EziGTM1 (Opal) were used as immobilization carriers for carrying out this preparative biotransformation. Upon setting-up reaction parameters (substrate concentration and molar ratio, temperature, pressure, residence time), 1 g of vidarabine was obtained in 55% isolated yield and >99% purity by simply running the flow reactor for 1 week and then collecting (by filtration) the nucleoside precipitated out of the exiting flow. Taking into account the substrate specificity of CpUP and AhPNP, the results obtained pave the way to the use of the CpUP/AhPNP-based bioreactor for the preparation of other purine nucleosides.
Study on the Stability of Produced Water from Alkali/Surfactant/Polymer Flooding under the Synergetic Effect of Quartz Sand Particles and Oil Displacement Agents
Authors: Huang Bin , Wang Chen , Zhang Weisen , Fu Cheng , Liu Haibo , Wang Hongwei
Published: March 2020

With the wide application of ASP (alkali/surfactant/polymer) flooding oil recovery technology, the produced water from ASP flooding has increased greatly. The clay particles carried by crude oil in the process of flow have a synergetic effect with oil displacement agents in the produced water, which increases the treatment difficulty of produced water. The stability of produced water is decided by the stability of oil droplets in the ASP-flooding-produced water system. The oil content, Zeta potential, interfacial tension and oil droplet size are important parameters to characterize the stability of produced water. In this paper, the changes of the oil content, Zeta potential, interfacial tension and oil droplet size of ASP flooding oily wastewater under the synergetic effect of different concentrations of quartz sand particles and oil displacement agents were studied by laboratory experiments. The experimental results show that the negatively charged quartz sand particles can absorb active substances in crude oil and surfactant molecules in the water phase and migrate to the oil–water interface, which increases the repulsion between quartz sand particles, decreasing the oil–water interfacial tension. Thus, the stability of oil droplets is enhanced, and the aggregation difficulty between oil droplets and quartz sand particles is increased. With the continually increasing quartz sand concentration, quartz sand particles combine with surfactant molecules adsorbed on the oil–water interface to form an aggregate. Meanwhile, the polymer molecules crimp from the stretching state, and the number of them surrounding the surface of the flocculation structure is close to saturation, which makes the oil droplets and quartz sand particles prone to aggregation, and the carried active substances desorb from the interface, resulting in the instability of the produced water system. The research on the synergetic effect between quartz sand particles and oil displacement agents is of great significance for deepening the treatment of ASP-produced water.
Apple Pomace as a Functional and Healthy Ingredient in Food Products: A Review
Authors: Lyu Fengzhi , Luiz Selma F. , Azeredo Denise Rosane Perdomo , Cruz Adriano G. , Ajlouni Said , Ranadheera Chaminda Senaka
Published: March 2020

Apple pomace is a major by-product obtained during apple juice processing. Several million metric tons of apple pomace are estimated to be generated worldwide every year. However, the recovery rate of this by-product is low. Pomace is commonly disposed and thrown away as a waste, which results in environmental problems and even public health hazards. As a by-product of the apple juice processing industries, pomace contains plenty of different varieties of nutritionally important compounds, such as carbohydrates, phenolic compounds, dietary fiber and minerals. These important compounds can be recovered from apple pomace, or there is even a possibility of using apple pomace in the food systems directly or after minimal processing. Therefore, apple pomace can be utilized in food products to improve their health benefits and commercial values. This review focuses on the current food applications and influence of apple pomace on the characteristics of various food products.