bluuebunny/crossref_metadata_2025 huggingface dataset:
Kilonova Emission from Black Hole–Neutron Star Mergers. II. Luminosity Function and Implications for Target-of-opportunity Observations of Gravitational-wave Triggers and Blind Searches
Authors: Zhu Jin-Ping , Wu Shichao , Yang Yuan-Pei , Zhang Bing , Gao He , Yu Yun-Wei , Li Zhuo , Cao Zhoujian , Liu Liang-Duan , Huang Yan , Zhang Xing-Han
Published: August 2021

We present detailed simulations of the kilonova and gamma-ray burst (GRB) afterglow and kilonova luminosity function from black hole–neutron star (BH–NS) mergers, and discuss the detectability of an electromagnetic (EM) counterpart in connection with gravitational wave (GW) detections, GW-triggered target-of-opportunity observations, and time-domain blind searches. The predicted absolute magnitude of BH–NS kilonovae at 0.5 days after the merger falls in the range [−10, −15.5]. The simulated luminosity function contains potential information on the viewing-angle distribution of the anisotropic kilonova emission. We simulate the GW detection rates, detectable distances, and signal duration for future networks of 2nd/2.5th/3rd generation GW detectors. BH–NSs tend to produce brighter kilonovae and afterglows if the BH has a higher aligned spin, and a less massive NS with a stiffer equation of state. The detectability of kilonovae is especially sensitive to the BH spin. If BHs typically have low spins, the BH–NS EM counterparts are hard to discover. For 2nd generation GW detector networks, a limiting magnitude of m
limit ∼ 23–24 mag is required to detect kilonovae even if high BH spin is assumed. Thus, a plausible explanation for the lack of BH–NS-associated kilonova detection during LIGO/Virgo O3 is that either there is no EM counterpart (plunging events) or the current follow-ups are too shallow. These observations still have the chance to detect the on-axis jet afterglow associated with a short GRB or an orphan afterglow. Follow-up observations can detect possible associated short GRB afterglows, from which kilonova signatures may be studied. For time-domain observations, a high-cadence search in redder filters is recommended to detect more BH–NS-associated kilonovae and afterglows.
Study of the Prompt Emission of Short Gamma-Ray Bursts Using a Multicolor Blackbody: A Clue to the Viewing Angle
Authors: Iyyani Shabnam , Sharma Vidushi
Published: August 2021

The prompt emission of short gamma-ray bursts (sGRBs) with known redshifts is analyzed using the model of a multicolor blackbody, which is interpreted as the emission from a nondissipative photosphere taking into account a power-law jet structure and the viewing geometry of the jet. We find nearly 69% and 26% of the sample is consistent with a multicolor blackbody and a pure blackbody model, respectively. Using this interpretation, we infer that nearly 57% (18%) of the sGRBs in our sample are observed within (or along the edge of) the jet core. The sGRB jets are deduced to possess a narrow core with a median θ

c
∼ 3°. This suggests the rate of sGRBs that would be viewed within the jet core to be 1.8–26 Gpc−3 yr−1. The power-law index of the decreasing Lorentz factor profile of the jet structure is deduced to be 1.3–2.2. The intrinsic luminosity is found to range between 1048–1053 erg s−1. The average values of the Lorentz factor and nozzle radius of the sGRB jets are inferred to be 210 (85) and 107.7 (109.6) cm for the cases when the photosphere forms in the coasting (accelerating) phase, respectively. The viability of the inferred values of the different parameters of the GRB outflow and viewing geometry within this physical interpretation enhances the prospect of the photospheric emission model explaining the observed GRB spectrum.
Review of the Merodon natans group with description of a new species, a key to the adults of known species of the natans lineage and first descriptions of some preimaginal stages
Authors: Vujić Ante , Tot Tamara , Andrić Andrijana , Ačanski Jelena , Šašić Zorić Ljiljana , Pérez-Bañón Celeste , Aracil Andrea , Veselić Sanja , Arok Maja , Mengual Ximo , van Eck André , Rojo Santos , Radenković Snežana
Published: August 2021

Abstract

Merodon natansgroup (Diptera, Syrphidae) taxa are reviewed using an integrative taxonomic approach combining morphological, morphometric and molecular techniques. The approach substantiates recognition of the three species:M. calcaratus(Fabricius, 1794),M. natans(Fabricius, 1794) andM. pulverisVujić & Radenković in Radenković et al. 2011, and reveals the existence of a new species,M. makrisiVujić, Radenković & Totsp. nov., which is described. It also highlights the existence of a series ofnatansgroup populations, especially on some of the Mediterranean islands, in the Levant and in the Afrotropical Region, for which more comprehensive data are required to clarify their status. A key is provided to thenatanslineage species currently recognised, and preimaginal stages of somenatans-group species are described for the first time. Redescriptions forM. calcaratusandM. natansare provided. A neotype is selected forM. natans. Lectotypes are designated forM. annulatus(Fabricius, 1794) andM. melancholicus(Fabricius, 1794).Merodon annulatusis recognised as a synonym ofM. natans.
Tanger, ville fermée
Authors: Perrier Antoine
Published: August 2021

Dans le Maroc colonial, Tanger est placée sous le mandat international de grandes puissances entre 1912 et 1956 et co-administrée en pratique par la France et l’Espagne. Toutefois, en dépit d’atouts géographiques et d’un régime qui promettait la liberté économique, la zone internationale reste pauvre pendant ces quarante années. Malgré les protestations des acteurs de la ville, la France et l’Espagne ont cherché à étouffer la vie économique de Tanger, au profit de leur propre zone de protectorat au Maroc. Après une enquête dans trois sites d’archives, cet article examine les stratégies économiques des deux puissances (douane, chemin de fer, tourisme). Il met en avant un cosmopolitisme de conflits, peu présent dans l’historiographie des villes internationales, et montre les effets économiques désastreux de l’internationalisation.
Dominique Kalifa, un historien au travail : entre héritage et transmission
Authors: Sauget Stéphanie
Published: August 2021

Moins d’un an après la disparition de Dominique Kalifa, cet article propose de revenir sur quelques-uns des apports de ce grand historien à la discipline et à la communauté historiennes. Il met en lumière quelques-unes des lignes de tensions à l’œuvre dans son travail : son approche des découpes chronologiques et temporelles ; son rapport au champ disciplinaire, et en particulier à l’histoire sociale et culturelle, ainsi que son rapport aux sources et son désir de partage avec le public le plus large possible.
Chine : la construction de sa puissance économique
Authors: Flouzat Denise
Published: August 2021

La Chine en tant qu’État présente une durée exceptionnelle : un bimillénaire. Elle a connu deux régimes, le premier sous forme d’Empire a été fondé en -202 avant JC et a eu une longue existence à travers une vingtaine de dynasties, se terminant en 1919 avec la chute de l’Empire. Le second régime a été créé le 1er octobre 1949 par Mao Tsé-toung qui a lancé à Pékin, devant la Cité Interdite, la République Populaire de Chine (RPC). De même, la Chine a subi, entre les deux régimes, une époque marquée par une occupation occidentale, semi coloniale, ainsi que par des luttes entre factions chinoises se disputant des morceaux de territoires. Mao Tsé-toung, jeune homme, était rendu furieux par la situation désespérée de son pays. Il n’a pas adhéré à la révolution démocratique promue par un médecin chinois, Sun Yat Sen, fondateur de la République de Chine. Il était attiré par la révolution menée en Union Soviétique. Il a adhéré au Parti Communiste Chinois (PCC) créé en 1921 dans lequel, par sa personnalité et par sa connaissance des armes, il s’est affirmé comme un leader susceptible de combattre les opposants au communisme. Cet article décrit l’historique de la politique chinoise depuis Mao Tsé-toung afin d’y expliquer comme corroléaire la puissance économique actuelle de la Chine de Xi Jinping.
New criteria for exponential stability in mean square of stochastic functional differential equations with infinite delay
Authors: Ngoc Pham Huu Anh
Published: August 2021

Stochastic functional differential equations with infinite delay are considered. A novel approach to exponential stability of such equations is proposed. New criteria for the mean square exponential stability of general stochastic functional differential equations with infinite delay are presented. Illustrative examples are given.
Optimal time-decay rate of global classical solutions to the generalized compressible Oldroyd-B model
Authors: Liu Shuai , Wang Yuzhu
Published: August 2021

In this paper, we investigate the optimal time-decay rates of global classical solutions for the compressible Oldroyd-B model in \begin{document}$ \mathbb{R}^n(n = 2,3) $\end{document}. Global classical solutions in two space dimensions are still open. We first complete the proof of global classical solutions in two space dimensions. Based on global classical solutions and Fourier spectrum analysis, we obtain the optimal time-decay rates of global classical solutions in two and three space dimensions. More precisely, if the initial data belong to \begin{document}$ L^1 $\end{document}, the optimal time-decay rate of solutions and time-decay rates of \begin{document}$ l(l = 1,\cdot\cdot\cdot,m) $\end{document} order derivatives under additional assumptions are established.
Digital products with $ PN_k $-adjacencies and the almost fixed point property in $ DTC_k^\blacktriangle $
Authors: Kang Jeong Min ,   Mathematics, School of Liberal, Arts Education, University of Seoul, Seoul 02504, Republic of Korea, Han Sang-Eon , Lee Sik ,   Department of Mathematics Education, Institute of Pure and Applied Mathematics, Jeonbuk National University, Jeonju-City Jeonbuk, 54896, Republic of Korea,   Department of Mathematics Education, Chonnam National University, Gwangju-City, 500-757, Republic of Korea
Published: August 2021

Given two digital images $ (X_i, k_i), i \in \{1, 2\} $, first of all we establish a new $ PN_k $-adjacency relation in a digital product $ X_1 \times X_2 $ to obtain a relation set $ (X_1 \times X_2, PN_k) $, where the term $ ''$$ PN $" means $ ''$pseudo-normal". Indeed, a $ PN $-$ k $-adjacency is softer or broader than a normal $ k $-adjacency. Next, the present paper initially develops both $ PN $-$ k $-continuity and $ PN $-$ k $-isomorphism. Furthermore, it proves that these new concepts, the $ PN $-$ k $-continuity and $ PN $-$ k $-isomorphism, need not be equal to the typical $ k $-continuity and a $ k $-isomorphism, respectively. Precisely, we prove that none of the typical $ k $-continuity (resp. typical $ k $-isomorphism) and the $ PN $-$ k $-continuity (resp. $ PN $-$ k $-isomorphism) implies the other. Then we prove that for each $ i \in \{1, 2\} $, the typical projection map $ P_i: X_1 \times X_2 \to X_i $ preserves a $ PN_k $-adjacency relation in $ X_1 \times X_2 $ to the $ k_i $-adjacency relation in $ (X_i, k_i) $. In particular, using a $ PN $-$ k $-isomorphism, we can classify digital products with $ PN_k $-adjacencies. Furthermore, in the category of digital products with $ PN_k $-adjacencies and $ PN $-$ k $-continuous maps between two digital products with $ PN_k $-adjacencies, denoted by $ DTC_k^\blacktriangle $, we finally study the (almost) fixed point property of $ (X_1 \times X_2, PN_k) $.
Decay/growth rates for inhomogeneous heat equations with memory. The case of large dimensions
Authors: Cortázar Carmen ,   Departamento de Matemática, Pontificia Universidad Católica de Chile, Santiago, Chile, Quirós Fernando , Wolanski Noemí ,   Departamento de Matemáticas, Universidad Autónoma de Madrid, 28049-Madrid, Spain,   Instituto de Ciencias Matemáticas ICMAT (CSIC-UAM-UCM-UC3M), 28049-Madrid, Spain,   IMAS-UBA-CONICET, Ciudad Universitaria, Pab. I, (1428) Buenos Aires, Argentina
Published: August 2021

We study the decay/growth rates in all $ L^p $ norms of solutions to an inhomogeneous nonlocal heat equation in $ \mathbb{R}^N $ involving a Caputo $ \alpha $-time derivative and a power $ \beta $ of the Laplacian when the dimension is large, $ N > 4\beta $. Rates depend strongly on the space-time scale and on the time behavior of the spatial $ L^1 $ norm of the forcing term.
Global Security Problem in the Arctic Zone
Authors: Christensen Carsten Sander
Published: August 2021

The American repeated offers to purchase Greenland has several times placed the world's biggest island at the heart of world affairs. However, as Greenland is actively seeking independence from Denmark, the future of Greenlandic defence has become crucial to understanding its independence aspirations. The threats against Denmark are very complex and are in a wider perspective the most unpredictable since the end of the Cold War. This is based not least on the aggressive behaviour of Russia, massive cyberattacks, China's economic aggressiveness, and the sustained terrorist threat against Europe and Denmark. This chapter examines the complexed international security situation in the Arctic zone. It focuses, especially, on the role of Greenland, de facto a demilitarized area in the northern hemisphere. What are the military and economic roles of Denmark, Russia, USA, Greenland, China, and further actors in the area? And what are the political, economic, military, and strategic consequences of the climate change in of the hot spots of security zones in the 2020s and in the future?
Cyber Warfare and NATO's New Security Concept
Authors: Karataş Ibrahim
Published: August 2021

This study analyzes NATO's efforts for defending itself and member states against cyberattacks originating from cyber space, which is the fourth domain of operations now, and the smartization of defense policies, respectively. It then elucidates whether the cyber defence can be ensured via practicing the smart defence paradigm. While the smart defence is already applied in military production and operations, and there is some success to a certain extent, to what extent smartizing cyber defence will be successful is a question whose answer is yet to be found. This chapter searches for the answer by applying NATO's smart defence concept to its cyber defence domain and tries to learn the possibility of the achievement of the new paradigm. In addition, it lays down its proposals such as imitating successful models and enlarging NATO so that it can include other partners in cyber space. Methodologically, a literature review was used to prepare the chapter.
Tantalum as a Novel Biomaterial for Bone Implant: A Literature Review
Authors: Putrantyo Ivan , Anilbhai Nikhit , Vanjani Revati , De Vega Brigita
Published: August 2021

Titanium (Ti) has been used in metallic implants since the 1950s due to various biocompatible and mechanical properties. However, due to its high Young’s modulus, it has been modified over the years in order to produce a better biomaterial. Tantalum (Ta) has recently emerged as a new potential biomaterial for bone and dental implants. It has been reported to have better corrosion resistance and osteo-regenerative properties as compared to Ti alloys which are most widely used in the bone-implant industry. Currently, Tantalum cannot be widely used yet due to its limited availability, high melting point, and high-cost production. This review paper discusses various manufacturing methods of Tantalum alloys, including conventional and additive manufacturing and also discusses their drawbacks and shortcomings. Recent research includes surface modification of various metals using Tantalum coatings in order to combine bulk material properties of different materials and the porous surface properties of Tantalum. Design modification also plays a crucial role in controlling bulk properties. The porous design does provide a lower density, wider surface area, and more immense specific strength. In addition to improved mechanical properties, a porous design could also escalate the material's biological and permeability properties. With current advancement in additive manufacturing technology, difficulties in processing Tantalum could be resolved. Therefore, Tantalum should be considered as a serious candidate material for future bone and dental implants.
Characterization of Scleraxis and SRY-Box 9 from Adipose-Derived Stem Cells Culture Seeded with Enthesis Scaffold in Hypoxic Condition
Authors: Prajasari Tabita , Zaim Chilmi Muhammad , Suroto Heri
Published: August 2021

The use of mesenchymal stem cells can add local improvements potential to enthesis tissue regeneration based on tropical activity through secretions of growth factors, cytokines, and vesicles (e.g. exosomes), collectively known as secretomes. This study aims to analyze secretomes characterization from adipose-derived mesenchymal stem cells seeded with enthesis tissue scaffold in hypoxic conditions and to analyze the influence of hypoxic environment to the characterization of secretomes. This is an in-vitro study using a Randomized Control Group Post-Test Only design. This study using Adipose Stem Cells (ASCs) were cultured in hypoxia (Oxygen 5%) and Normoxia (21%) condition. The scaffolds are fresh-frozen enthesis tissue and was seeded in the treatment group and compared to control. The evaluation of Scleraxis (Scx) and SRY-box (Sox9) was measured using ELISA on the 2nd, 4th, and 6th days. Comparison of Scx levels between each evaluation time showed a positive trend in a group with scaffold in hypoxia condition although it has no significant differences (p=0.085), with the highest level on day 6, that is 13,568 ng/ml. Conversely, the comparison of Sox9 showed significant differences (p=0.02) in a group with scaffold in hypoxia condition, with the highest level on day 4, that is 28,250 ng/ml. The use of enthesis scaffold seeded in adipose-derived mesenchymal stem cells in hypoxic conditions shows a positive trend as regenerative effort of injured enthesis tissue through Scleraxis and Sox9 secretomes induction.
Nanocrystalline Composite Smart Coating Deposition for Corrosion Self-Healing of Mild Steel
Authors: Fayomi Oyo Sunday I. , Oyedepo Sunday O. , Ighravwe D.E. , Aikhuele Daniel O.
Published: August 2021

This work examine the potential of ZrB2 in the presence of Ni-P-Zn sulphate rich bath coating on mild steel under change in time from 10-25 min. The coating pH of 5, current density of 1 A/cm2, and stirring rate of 250 rpm was considered in the fabrication process. The microstructure evolution and properties of the deposited coating was analysed using a scanning electron microscope enhanced with energy dispersive spectroscopy (SEM/EDS). All deposited composite coating was investigated in 0.5 M H2SO4 and 3.5% NaCl with the help of linear polarization and open circuit potential. From the result, a solid crystal formation containing zirconium boride was seen from the SEM study. At 25 min a remarkable dispersed and even thin film was noticeable at the interface. From all indication, coating produced with Ni-P-Zn-10ZrB2 at 25 min provides a passive response against corrosion damage. Keywords: Electrodeposition, interface, nanocrystalline, structure, coating
Heat Transport of Casson Nanofluid Flow over a Melting Riga Plate Embedded in a Porous Medium
Authors: Adeosun Adeshina Taofeeq , Gbadeyan Jacob Abiodun , Lebelo Ramoshweu Solomon
Published: August 2021

This article investigates the flow of Casson nanofluid induced by a stretching Riga plate in the presence of a porous medium. The implication of the Riga plate is to generate electromagnetohydrodynamic force which influences the fluid speed, and as well applicable in delaying boundary layer separation. The complexity of the equations governing the problem is reduced using similarity transformation. The resulting coupled nonlinear ordinary differential equations are solved by employing Chebyshev collocation scheme (CCS) and validated with Galerkin weighted residual method (GWRM). The influence of parameters, such as modified Hartmann number and melting parameter, on the nanofluid flow, heat, and mass transfer is considered. Some of the major findings include that modified Hartmann number tends to increase nanofluid flow. Also, increasing the value of melting parameter is in favor of both velocity and nanoparticle volume fraction profiles but diminishes temperature profile. The application of this work can be found in polymer synthesis, metallic processing, and electromagnetic crucible systems.
Adsorptive Removal of Ibuprofen from Waste Stream Using Sawdust-Based Adsorbents
Authors: Adesokan Saheed Ademola , Giwa Abdur Rahim Adebisi , Bello Isah Adewale
Published: August 2021

Wood sawdust, one the high volume agricultural wastes in Nigeria, occupies space and constitutes environmental nuisance. Burning, it produces green house gases. Converting it to adsorbents is economical and environmental benign. This work assessed the adsorptive capacities of two Danielliaoliveri sawdust-based adsorbents for the removal of ibuprofen from waste stream. The sawdust was carbonized and activated with ZnCl2 and H3PO4 to produce adsorbents code-named ZCAC and PAAC respectively. The physicochemical properties of the adsorbents were determined and batch adsorption experiments performed. The optimum pH for the adsorption of ibuprofen onto the ZCAC and PAAC was 3. The isotherm studies revealed that the Ibuprofen (IBU)-ZCAC system data fitted Redlich-Peterson and Langmuir models. The data also fitted Pseudo-second order and Boyd kinetics, defined intraparticle diffusion of the adsorbate molecules. The process was physical and endothermic. For the adsorption onto PAAC, the data fitted the Freundlich and the Halsey models. The data also fitted the Pseudo-second order and the Elovich kinetics. The process was endothermic. The adsorption capacities of ZCAC and PAAC for IBU were 3.876 and 15.385 mg/g respectively. ZCAC and PAAC were promising adsorbents for remediation of wastewater contaminated with ibuprofen.
CTCS Schemes for Second Order Wave Equation: Numerical Results and Spectral Analysis
Authors: Appadu Appanah Rao , de Waal Gysbert Nicolaas
Published: August 2021

IIn this paper, two finite difference methods are used to solve the one-dimensional second order wave equation with constant coefficients subject to specified initial and boundary conditions. Two numerical experiments are considered. The two methods are Central in Time and Central in Space scheme with second order accuracy in both time and space, abbreviated as CTCS (2,2) and Central in Time and Central in Space scheme with second order accuracy in time and fourth order accuracy in space, abbreviated as CTCS (2,4). Properties such as consistency and stability are studied. We also perform spectral analysis of dispersive and dissipative properties of the two methods. Two numerical experiments are considered, and the numerical results are displayed.
Mechanical Properties of SiC/Gr Reinforced Hybrid Aluminum Composites after Heat Treatment
Authors: Rahmalina Dwi , Sukma Hendri , Rokhim Abdul , Suhadi Amin
Published: August 2021

Metal matrix composite has been developed to improve mechanical properties for the automotive component application. One crucial factor in achieving excellent mechanical properties is improving the properties of the aluminum matrix of composite by the heat treatment process. The mechanical properties of Al-Mg-Si matrix composites alloyed with Zn and reinforced with 5% SiC and 5%Gr particle were examined after the heat treatment process. The aluminum matrix is melted inside the crucible furnace at 850 °C and is added with SiC/Gr particle, followed by stirring at 7500 rpm to optimize the mixing of the composite. Then, the composite is poured into the preheated mold at 300 °C and then squeezed with 30 MPa of pressure. The heat treatment process consists of three steps; solution treatment, quenching, and artificial aging. The aging process is conducted with variation of temperature (140 °C, 180 °C and 200 °C) and holding time (2, 4, and 6 hours). The test results show that the mechanical properties of aluminum matrix composite tend to increase after the heat treatment process. The optimum mechanical properties are achieved at the aging temperature of 200 °C for 6 hours, with the hardness value of 60.3 HRA and the impact value of 0.112 Joule/mm2.
Comparison of Flexural Behaviour of Composite FRP with UHPC I-Beam Using Finite Element Analysis
Authors: Saidin Siti Shahirah , Jamadin Adiza , Kudus Sakhiah Abdul , Mohd Amin Norliyati
Published: August 2021

Concrete can be considered as the ultimate construction material since it is the most widely used in the construction materials due to its extensive strength and reasonable cost. Recent years, large investments have been spent for studies on the new advanced materials to enhance the performance and functionality of conventional concrete especially for bridge structure. The application of Ultra-high-performance concrete (UHPC) as advanced materials in bridge application is well established since it able to construct 100m long highway bridge without reinforcement, while fiber reinforced polymers (FRP) required some studies on the optimum composition for bridge application. In this paper, A33 composite FRP from the previous research is studied under 4-point bending test to study the flexural behavior and compared to the UHPC. Three-dimensional finite element analysis of FRP and UHPC I-beam are modelled using Abaqus software to determine and compare the beam deflection and stress. The deflection and stress UHPC and FRP I-beam model being validated with experimental result of four-point bending test and theoretical of equivalent method in previous research. The results from the analytical and experimental are compared and shows good agreements. The presented modeling offers an economical and efficient tool to investigate the structural performance of FRP and UHPC in construction materials.
Influence of Welding Speed on Hard-facing Deposited by MIG Welding
Authors: Chanchana Atthakorn , Sriswat Manus , Sangkatip Rittichai , Obrom Witoon , Panawan Pitak
Published: August 2021

Hard-facing is one of processes for repairing metallic surface of equipment or parts of machinery that are lost due to outworn mechanism. Therefore, hard-facing requires suitable variables to obtain the hardest hard-faced metals. This research aimed to study influence of welding speed on hard-facing affecting microstructure and hardness of the hard-faced metals on JIS-S45C carbon steel with MIG welding. According to the experiment, hard-facing with welding speed at 250 mm/min contained dilution of elements lower than welding speed at 200 and 300 mm/min. Therefore, the hard-faced metals contained elements the most including Silicon 2.25 %, Chromium 6.12 % and Manganese 0.51 %, which affected the enhancement of mechanical properties of welded metals. The hard-faced metal had highest average hardness at 705.9 HV0.1.
Gravity Casting and Hot Forging of Al-Mg Alloy and Al-Mg Alloy with Fe Added
Authors: Haga Toshio , Sugishita Takumu , Fse Hiroshi , Watari Hisaki , Nishida Shinichi
Published: August 2021

Al-4.7%Mg alloy with 0, 0.2, 0.4, 0.6 and 0.8% Fe added was cast using a copper mold and an insulator mold. The cooling rates of ingots cast using the copper mold and the insulator mold were 30.6 °C/s and 0.5 °C/s, respectively. The tensile stress and elongation of the ingots cast by the copper mold were superior to those cast by the insulator mold. The addition of Fe did not lead to tensile stress, but the elongation became smaller as the Fe content increased. The elongation of the ingot cast using the copper mold became much smaller on addition of only 0.2% Fe. The tensile stress and elongation were improved by hot forging with 50% reduction. The elongation of the ingots with Fe added was significantly improved by the hot forging. The degree of improvement of the tensile stress and elongation for the ingots cast using the insulator mold was remarkable.
Corrosion of Aluminum Metal Matrix Composites: A Review of the Effect of Manufacturing Processes, Processing Routes and Secondary Phases
Authors: Loto Roland Tolulope , Adeleke Adeyinka
Published: August 2021

The vulnerability of Al matrix composites to general and preferential corrosion is due to the intrinsic proneness of binary materials to undergo advanced deterioration. Control of the prevalent sites for evolution and proliferation of confined corrosion strongly influence the corrosion resistance of the composites. The problem for enhanced utilization of composites, has exacerbated with attention on the productive life and resilience to environmental degeneration during operational service. This can be achieved through proper comprehension of the electrochemical mechanism, the intriguing nature of SiC grains and their importance on the secondary phases, metallurgical configuration, and manufacturing process routes. This review confirms the relevance of secondary phases, microstructures and manufacturing processes in relation to SiC particles on the corrosion invulnerability of Al matrix composites to further add corrosion mitigation in design and and technological advancement.
Development of artificial sill pillar design, Lupin Mine, Northwest Territories, part 2: pre-mining ground stress determinations
Authors: Arjang B
Published: August 2021

The Echo Bay Mines Ltd. Lupin operation in Northwest Territories produces gold from a steeply dipping orebody by sub-level longhole open stope mining, leaving sill pillars in the ore. To increase ore recovery, a joint research project has been established to
design and develop guidelines for artificial sill pillars. To provide background information for stability evaluations, pre-mining ground stress determinations were conducted on the 410 m and 890 m levels of the mine.
Ground stress determination from overcoring strain relief measurements indicates that, generally, the maximum principal compressive stress is horizontal in a NE/SW direction, and the intermediate principal compressive stress is sub-horizontal prevailing in a NW/SE direction. The minimum principal
compressive stress is sub-vertical with varying direction. Stress gradients for maximum, intermediate and minimum principal compressive stresses vary, ranging from 0.0430 to 0.0693 MPa/m, 0.0271 to 0.0505 MPa/m, and 0.0127 to 0.0397 MPa/m, respectively. A comparison of average stress gradients,
however, suggests that the Lupin Mine data follow the trend established from underground stress determinations in the Canadian Shield.
Design and operation of an automated beta-particle counting system for the measurement of 220Rn (and 222Rn) progeny
Authors: Bigu J
Published: August 2021

A fully automated system of the continuous (active) type has been designed for the unattended quantification of 222Rn progeny and 220Rn progeny in calibration and test facilities, as well as working and living environments. The system uses a beta-particle
detector and associated electronic circuitry, in conjunction with an in-house microprocessor-based processing interface card and a personal computer, operated by specially developed in-house software. The system represents a significant improvement over systems using alpha-particle detectors because
of its enhanced flexibility of design and virtual elimination of plate-out effects in the sampling head, and of self-absorption phenomena in the sampling filter. The beta-particle system was tested and calibrated in a Radon/Thoron Test Facility (RTTF) of the walk-in type under a variety of
experimental conditions. For the geometry used for this system, the Potential Alpha Energy Concentration (PAEC) in air can be calculated by the expression PAEC -264 Nbeta (cpm/microjoule*m-3), where Nbeta is the beta-particle system count rate in counts per minute (cpm).
Sharing is caring: Knowledge sharing at the city of Johannesburg Library and Information Services
Authors: Nkomo Lydia , Maluleka Jan R. , Ngulube Patrick
Published: August 2021

Background: The strength of an organisation lies in its ability to manage its human capital. Ideally, organisations that wish to remain service-oriented in this Fourth Industrial Revolution need to comprehend the importance of tacit knowledge and ensure its retention and sharing at all levels. Many organisations fail to capitalise on the value within their tacit knowledge reserves until when employees leave their jobs. Quite often, the importance of the lost knowledge will be felt when a new employee takes over.Objectives: The aim of this study was to examine how tacit knowledge is shared at the city of Johannesburg Library and Information Services.Method: This qualitative study employed the knowledge conversion theory to examine the management of tacit knowledge at the City of Johannesburg Library and Information Services. A case study design was used, and data were collected through semi-structured interviews and document analysis.Results: The key findings revealed that the City of Johannesburg Library and Information Services does not have an effective strategy to manage tacit knowledge and does not utilise available knowledge management resources. Furthermore, knowledge sharing is very minimal.Conclusion: The study concludes that the City of Johannesburg Library and Information Services does not manage the tacit knowledge that is at their disposal, and knowledge sharing is also not encouraged. The study recommends that an effective community of practice for knowledge sharing and a policy for knowledge sharing should be established at the City of Johannesburg Library and Information Services.
Anesthetic Management and Postoperative Outcome of Pediatric Patients with Grade 3 Pancreatic Trauma Injury and Asymptomatic COVID-19
Authors: Antares Vesta , Adhi Mahendratama Purnama , Saputra Rory Denny
Published: August 2021

The global pandemic of coronavirus disease 2019 (COVID-19) has inevitably affected pediatric surgical services. Clinical manifestations of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection in pediatrics are generally asymptomatic to mild, so they are often not detected during initial screening. In adult population, the postoperative mortality of patients infected with SARS-CoV-2 is 23.8%. The possibility of SARS-CoV-2 transmission to health workers during surgery, the increasing postoperative mortality, and the risk of postoperative complications pose challenges for anesthetists in treating pediatric patients with COVID-19 undergoing emergency surgery. Here, we describe the management of anesthesia and postoperative evaluation of a pediatric patient with asymptomatic COVID-19 who underwent emergency laparotomy due to grade 3 traumatic pancreatic injury under general anesthesia. We found no worsening of clinical symptoms or complications related to COVID-19 on 30 days after surgery. The increase in inflammatory markers was not related to COVID-19 but was an inflammatory response to traumatic injury and surgery.
Serratus Anterior Plane Block in Modified Radical Mastectomy Surgery
Authors: Datu Madonna Damayanthie , Prasetyadhi Jokevin
Published: August 2021

Postoperative breast pain may lead to poorer outcome if left untreated. Common analgesia modalities for postoperative breast pain include opioids and regional anesthesia. However, both of these modalities can cause significant side effects or complications. Serratus anterior plane (SAP) block is a new procedure that is relatively easier to perform and safer, compared with other modalities. Previous studies have reported its usefulness in reducing the need for both intraoperative and postoperative opioids. We report two patients who underwent SAP block combined with general anesthesia in modified radical mastectomy (MRM). Patient 2 was given rescue analgesia during the intraoperative period. The administration of postoperative opioids did not exceed 24 h in both patients. Pain assessment using Numeric Rating Scale showed minimal postoperative pain. No side effects were found during 24-h monitoring period. SAP block can be used as one of the modalities in managing the pain of MRM surgery.
A Comparison between Intravenous Ondansetron and Granisetron in the Preventive Management of Postoperative Nausea and Vomiting in Patients Undergoing Cesarean Section under Spinal Anesthesia
Authors: Parripati Lakshmi Deepthi , Bandarupalli Seshatalpa Sai , Ramella Manoj , Sandhya L
Published: August 2021

Background:

Efforts are still conducted to reduce side effects of anesthesia, such as postoperative nausea and vomiting (PONV). This study was performed to compare the effectiveness of prophylactic use of intravenous Ondansetron (4 mg) and Granisetron (2 mg) in the preventive management of postoperative nausea and vomiting in women undergoing elective lower (uterine) segment cesarean section (LSCS).

Patients and Methods:

A total of 100 patients belonging to the American Society of Anesthesiologists (ASA) Grade I and II posted for elective LSCS were included in the study. 100 patients were further divided into two groups (n = 50), i.e., Group O (ondansetron) and Group G (granisetron). This study was conducted from November 2017 to August 2019 on 100 ASA I and ASA II patients, aged from 18 to 35 years who underwent elective LSCS under the subarachnoid block.

Results:

Both drugs Ondansetron and Granisetron showed prevention of PONV (Granisetron showed 80% response and Ondansetron showed 44% response). Both drugs have shown promising results for a shorter duration in postoperative care but Ondansetron showed a higher number of PONV incidences than Granisetron in long duration.

Conclusion:

Granisetron is effective than Ondansetron in preventing nausea and vomiting in the late postoperative period with fewer side effects.
The Effect of Low-Dose Ketamine to Median Cerebral Artery's Mean Flow Velocity in Patients Underwent Noncerebral Surgery Under General Anesthesia
Authors: Senapathi Tjokorda Gde Agung , Suarjaya I Putu Pramana , Lizal Roy
Published: August 2021

Background:

Ketamine can provide sedation and analgesia in specific doses. Whereas most other anesthetic agents exert a suppressive effect on the cardiovascular system and can lower blood pressure, ketamine can have the opposite effect. Although it provides many benefits, the use of ketamine is still limited in patients who are at the risk of increased intracranial pressure, such as head injury and stroke. The present study aims to compare the mean flow velocity-medial cerebral artery's (MFV-MCA) in patients receiving propofol with patients receiving a low-dose combination of propofol and ketamine.

Materials and Methods:

This was an experimental study with a double-blind, randomized controlled trial design. A total of 58 ASA I-II patients who underwent surgery with general anesthesia technique were collected by the consecutive sampling technique. The sample was divided into two groups: Group A received a low dose of ketamine after the patient was induced with propofol and Group B received NaCl 0.9% after the patient was induced with propofol. We used transcranial Doppler to measure the MFV-MCA before, 5 min after, and 10 min after the administration of ketamine.

Results:

We found no statistical difference between the groups in terms of MFV-MCA values before ketamine administration (P = 0.908), 5 min after ketamine administration (P = 0.890), and 10 min after ketamine administration (P = 0.981).

Conclusion:

The administration of low-dose ketamin at 0.3 mg/kg after induction did not increase the MFV-MCA in patients who underwent general anesthesia using propofol.
Peripheral Giant Cell Granuloma
Authors: Gautam Surbhi , Banerjee Sucharita , Datta Sanjukta , Bagchi Somen
Published: August 2021

Peripheral giant cell granuloma (PGCG) has been given various names over the years such as peripheral giant cell tumor, reparative giant cell granuloma, giant cell epulis, giant cell hyperplasia, and osteoclastoma. It is the most commonly occurring lesion of the jaw developing from periosteum's connective tissue or periodontal membrane. It is predominantly seen in females in the mandibular region and usually in their late 40s. However, we hereby present a rare case of PGCG found in a male, in the maxillary posterior region, and in his early 20s.
Antioxidant Effects of L-citrulline Supplementation in High-fat Diet- and Dexamethasone-induced Type-2 Diabetes Mellitus in Wistar Rats (Rattus norvegicus)
Authors: Hassan-Danboyi Evelyn , Jimoh Abdulazeez , Alhassan Abdulwahab , Danboyi Timothy , Mohammed Kabir Ahmed , Dubo Augustine Banlibo , Haruna Jamilu , Yakubu Bulus Billy
Published: August 2021

Background:

Oxidative stress is one of the major mechanisms underlying the onset and development of type-2 diabetes mellitus (T2DM). Although L-citrulline possesses antioxidant effect, little or no data exist linking such effects in diabetic setting.

Objective:

This study aimed to evaluate the effect of L-citrulline on biomarkers of oxidative stress in diabetic Wistar rats.

Materials and Methods:

Thirty male Wistar rats 10–12 weeks old and weighing 200–250 g were randomly assigned into six groups of five rats each. Group I rats were fed normal diet, while diabetes was induced in the other groups with high-fat diet (HFD) and dexamethasone intraperitoneally (1 mg/kg) for 21 days. Thereafter, Group III received metformin 100 mg/kg/day orally, and Groups IV, V, and VI received 200, 400, and 800 mg/kg/day L-citrulline, respectively, for another 21 days. Data were analyzed using SPSS and values at P < 0.05 were considered statistically significant.

Results:

The malondialdehyde concentrations were significantly reversed from 42.0 ± 0.42 μmol/mL in the diabetic group to 20.7 ± 0.81, 22.2 ± 0.75 and 22.1 ± 0.39 μmol/mL at 200, 400, and 800 mg/kg/day, respectively. The L-citrulline remarkably ameliorated the reduction in superoxide dismutase activity noted in the diabetic group (13.0 ± 0.44 μmol/mL) at all doses (17.8 ± 0.37, 16.0 ± 0.51, and 23.7 ± 0.78 μmol/mL at 200, 400, and 800 mg/kg, respectively). Similarly, there was a corresponding significant increase in the catalase activity, especially at 400 mg/kg (13.7 ± 0.43 ng/mL) and 800 mg/kg (14.6 ± 0.54 ng/mL) compared to the diabetic group (10.8 ± 0.41 ng/mL). The marked reduction in reduced glutathione level observed in the diabetic group (22.9 ± 0.69 mg/mL) was markedly ameliorated by L-citrulline supplementation at all doses (42.9 ± 1.08, 46.4 ± 0.53, and 45.2 ± 1.00 mg/mL at 200, 400, and 800 mg/kg, respectively).

Conclusion:

This study shows that L-citrulline supplementation has antioxidant effects in HFD- and dexamethasone-induced T2DM in male Wistar rats.
Helium-Oxygen Mixture Bag, a Novel Way for Extubation of COVID-19 Patients
Authors: Bawazeer Mohammed A. , Dahhan Talal I. , Gattan Marame K. , Nahhas Ahmad A , Almutairi Hejab J , J. Ko Matthew Y. , Lapinsky Stephen E.
Published: August 2021

Background:

Coronavirus disease 2019 (COVID-19) has been a worldwide pandemic in 2020; necessitating significant changes in patient-care procedures. Because of the risk of transmission to health care workers (HCWs) and the shortage of personal protective devices worldwide, novel protective barriers during aerosol-generating procedures have been developed. The intubation box has been proposed and gained popularity. A safe way for extubating patients with COVID-19 in critical care settings does not exist. This report discusses the development and assessment of the efficacy of using a Helium-Oxygen mixture (Heliox) filled bag during the extubation phase for the protection of HCW.

Study Design and Methods:

This methodology was developed at two tertiary care hospitals in Riyadh, Saudi Arabia and Toronto, Canada. We describe a novel way using a bag filled with Heliox bag. We performed extubation of an intubated manikin with and without using the Heliox bag. The cough during extubation was simulated using a fluorescent dye-filled balloon, which was inflated with a hidden oxygen tube until it bursts. We used an ultraviolet (UV) light source to assess the aerosols generated during extubation.

Results:

During extubation using the Heliox bag, droplets of the fluorescent dye were all contained within the Heliox bag and only found on the manikin chest. While during extubation without using Heliox bag, using the UV light, we found droplets of the fluorescent dye on the HCW mask and hand, the bed, the floor, and wall of the room.

Conclusion:

In our simulated experiment, we found that the Heliox bag is an easy and reproducible way for extubating patients with COVID-19 and any other airborne disease. We also found that the Heliox bag is an effective way to protect HCW.
Determination of gill-net selectivity for King Fish (Scomberomorus Commerson, Lacepede 1800) using Mesh size in Sungailiat, Bangka Belitung Province
Authors: Rengi Pareng , Nasution Polaris , Brown Arthur , Tambunan Ayu Nita Ervina
Published: August 2021

Selectivity is a fishing gear characteristic capable of catching fish of a specific size and species from the existing population distribution. Mesh size is one of the important factors that influence gillnets’ selectivity, because different length-classes of fish are caught by them. This report focuses on the selectivity of two mesh sizes of gillnets (8.89 cm and 10.16 cm) on mackerel's catch and constructing a gillnet in Sungailiat waters. Experimental fishing methods and selectivity analysis were used for the fishing gear’s more selective preparation, if the largest fishing ratio's value at the fork length (L) is high and the standard deviation value (S) is closer to 1. It is concluded that to be more selective a largest S (L) value of 0.999267194 at fork length (L=54.95 cm), and with a larger value of S (L) 0.997096071 and with (L=66.55 cm) for mesh Sizes 8.89 cm and 10.16 cm, respectively.
Global Trends of Regional Health Information Systems and Suggested Strategic Utilization of their Medical Information
Authors: Park Hyejin , Kang Sung-Hong , Lee Young Sung , Lee In-Sik , Hwangbo Yul , Cho Kyunghee
Published: August 2021

Objectives: Along with the exponentially-growing data produced and accumulated every day through mobile platforms, social networking services, the Internet, and other media, information is becoming increasingly important as a strategic resource. This report presents specific and clear directions and suggests empirical project plans regarding innovations in regional health information systems to promote the utilization of medical information.Methods: We reviewed and examined documents about global trends and examples of regional health information systems. The problems and solutions of health information utilization and regional health information systems in Korea were analyzed.Results: This study presented examples of the establishment of health information systems, problems in the use of local healthcare information, and an empirical project for improvement.Conclusions: The results of this study imply the need for long-term and systematic approaches for the use of medical information and the establishment of a local healthcare information system, along with implementation plans. As a first step, it is imperative to clarify the goal of building a medical information system, the information that must be provided to build the system, and the data that should be collected to provide such information, while moving away from the mentality of focusing on technology-oriented medical information services. In addition, it is necessary to consider information governance, data-based service development, and the medical innovation framework, which are ways to efficiently manage, utilize, and systemize the data to be collected.