bluuebunny/crossref_metadata_2025 huggingface dataset:
A Quaternion-Based Piecewise 3D Modeling Method for Indoor Path Networks
Authors: Jian Hongdeng , Fan Xiangtao , Liu Jian , Jin Qingwen , Kang Xujie
Published: February 2019

Generating 3D path models (with textures) from indoor paths is a good way to improve the visualization performance of 3D indoor path analysis. In this paper, a quaternion-based piecewise 3D modeling method is proposed to automatically generate highly recognizable 3D models for indoor path networks. To create such models, indoor paths are classified into four types of basic elements: corridor, stairs, elevator and node, which contain six kinds of edges and seven kinds of nodes. A quaternion-based method is devised to calculate the coordinates of the designed elements, and a piecewise 3D modeling method is implemented to create the entire 3D indoor path models in a 3D GIS scene. The numerical comparison of 3D scene primitives in different visualization modes indicates that the proposed method can generate detailed and irredundant models for indoor path networks. The result of 3D path analysis shows that indoor path models can improve the visualization performance of a 3D indoor path network by displaying paths with different shapes, textures and colors and that the models can maintain a high rendering efficiency (above 50 frames per second) in a 3D GIS scene containing more than 50,000 polygons and triangles.
Cloud Based Virtual Reality Exposure Therapy Service for Public Speaking Anxiety
Authors: Šalkevičius Justas , Miškinytė Audronė , Navickas Lukas
Published: February 2019

Public speaking anxiety is commonly treated using cognitive behavioral therapy. During the therapy session, the patient is either asked to vividly imagine and describe the feared stimulus or is confronted with it in the real world. Sometimes, however, it can be hard to imagine the object of fear or to create a controllable environment that contains this stimulus. Virtual reality exposure therapy (VRET) can help solve these problems by placing the patient in a simulated 3D environment. While standalone VRET applications have been investigated for more than 25 years, we are analyzing the viability of a cloud-based VRET system. In this paper, we discuss the architectural and technical choices made in order to create a mobile and lightweight solution that can be easily adapted by any psychology clinic. Moreover, we are analyzing data gathered from 30 participants who have undergone a VRET session for public speaking anxiety. Finally, the collected psychophysiological signals including galvanic skin response (GSR) and skin temperature are processed and investigated in order to evaluate our cloud-based VRET system.
The Importance of the Hedgehog Signaling Pathway in Tumorigenesis of Spinal and Cranial Chordoma
Authors: Akhavan-Sigari Reza , Schulz-Schaeffer Walter , Angelika Harcej Amanda , Rohde Veit
Published: February 2019

Chordomas is rare malignant bone tumors thought to arise from remnants of embryonic notochord along the spine, frequently at the skull base and sacrum. Although chordoma is slow growing tumors, while are extremely recurrent, and aggressive, as well as the rate of prognosis remains poorly. Radical surgery and high-dose radiation are the most used treatments. Currently, there is no effective chemotherapeutic standard for chordomas. The Hedgehog (HH) pathway adjusts various processes included in expansion and differentiation of tissues and organs throughout the fetus’s life, furthermore cell growth and differentiation in the adult organism, of the cell in an adult organism, in which acute anesthesia is involved in multiple cancers. To study the role of signaling the hedgehog in the base of the skull and sacrum chordomas, the expression of SHH and GLI-1 levels were detected immuno histochemically, Additionally, PTCH-1 and GLI-1 expressions were distinguished by in- Situ- hybridization. Based on the findings presented herein, it is likely that the HH signal cascade was revealed even in cranial, where consecoently spinal chordoma and their recurrences play an important role. Our staining exhibited a canonical, ligand- dependent and autocrine Hedgehog signaling in skull base and sacrum chordomas including relapse. Due to the high levels of SHH and GLI-1 expression in all investigated chordoma samples, the study suggests a possible autocrine ligand-dependent activation of the canonical HH signaling cascade. A paracrine or non-canonical pathway cannot be excluded. Our results suggest that Hedgehog-inhibitors, like SHH-, GLI- and SMO- inhibitors, might serve as a potential and effective target for the treatment of chordomas.
Numerical Investigation of Grooved Shaft Effects on the Rotary Lip Seal Performance with Relative Lip Motion
Authors: Lahjouji Imane , El Gadari M’hammed , Radouani Mohammed
Published: February 2019

It is generally agreed that radial lip seals are used in systems with a rotating shaft and a stationary lip. However, according to previous work, it was demonstrated that relative motion between the shaft and the lip has substantial effects on the hydrodynamic lifting load and sealing performances. Nowadays, new generations of textured shafts have emerged in order to reduce friction torque and improve reverse pumping, but no study has confirmed the effect of the relative motion between the rough lip and the shaft grooves on the rotary lip seal performances. In this work, an isothermal hydrodynamic lubrication was performed in transient conditions to investigate the effect of the relative velocity between an oblique grooved shaft and a rough lip. After confirming the validity of the current model with respect to previous works, simulations have underlined the effect of the grooved shaft with relative lip motion on the rotary lip seal performance. Indeed, by keeping the same relative velocity between surfaces, it is shown that moving the shaft with a rate higher than that of the lip surface could produce an important reverse pumping and reduce the friction torque significantly, in comparison with cases where the shaft velocity is weaker.
The Influence of Post-Weld Heat Treatment on the Microstructure and Fatigue Properties of Sc-Modified AA2519 Friction Stir-Welded Joint
Authors: Kosturek Robert , Śnieżek Lucjan , Wachowski Marcin , Torzewski Janusz
Published: February 2019

The aim of this research was to investigate the influence of post-weld heat treatment (PWHT, precipitation hardening) on the microstructure and fatigue properties of an AA2519 joint obtained in a friction stir-welding process. The welding process was performed with three sets of parameters. One part of the obtained joints was investigated in the as-welded state and the second part of joints was subjected to the post-weld heat treatment (precipitation hardening) and then investigated. In order to establish the influence of the heat treatment on the microstructure of obtained joints both light and scanning electron microscopy observations were performed. Additionally, microhardness analysis for each sample was carried out. Fatigue properties of the samples in the as-welded state and the samples after post-weld heat treatment were established in a low-cycle fatigue test with constant true strain amplitude equal to ε = 0.25% and cycle asymmetry coefficient R = 0.1. Hysteresis loops together with changes of stress and plastic strain versus number of cycles are presented in this paper. The fatigue fracture in tested samples was analyzed with the use of scanning electron microscope. Our results show that post-weld heat treatment of AA2519 friction stir-welded joints significantly decreases their fatigue life.
Mineralogical, Textural and Physical Characterisation to Determine Deterioration Susceptibility of Irulegi Castle Lime Mortars (Navarre, Spain)
Authors: Ponce-Antón Graciela , Arizzi Anna , Zuluaga Maria Cruz , Cultrone Giuseppe , Ortega Luis Angel , Agirre Mauleon Juantxo
Published: February 2019

Archaeological lime mortars from the Tower Keep and West perimeter wall of Irulegi Castle (Navarre, Spain) were analysed to determine susceptibility to deterioration. Chemical, mineralogical, textural and physical characterisation was performed by different tests and multianalysis techniques in order to determine the intrinsic features of the original historical mortars at the castle. Samples from the Tower Keep are more prone to deteriorate compared with the West perimeter wall due to high water absorption capacity and high porosity. A high degree of pore interconnection, high desorption index and the presence of high pore volume in the 0.01 to 1 µm size range affect the mortar durability since pores retain water longer inside the mortar. Local environment conditions with persistent annual rainfall, high humidity and temperature variations contribute to the decay process of the original mortar. Characterisation of historical mortars not only allows better understanding of susceptibility to deterioration but also helps the design of compatible and durable repair mortar for future interventions on historical heritage. Compatibility of new materials with the historical mortar will be ensured by studying mortar characteristics and properties.
Limits of Cation Solubility in AMg2Sb2 (A = Mg, Ca, Sr, Ba) Alloys
Authors: Peng Wanyue , Zevalkink Alexandra
Published: February 2019

A M 2 X 2 compounds that crystallize in the CaAl 2 Si 2 structure type have emerged as a promising class of n- and p-type thermoelectric materials. Alloying on the cation (A) site is a frequently used approach to optimize the thermoelectric transport properties of A M 2 X 2 compounds, and complete solid solubility has been reported for many combinations of cations. In the present study, we investigate the phase stability of the AMg 2 Sb 2 system with mixed occupancy of Mg, Ca, Sr, or Ba on the cation (A) site. We show that the small ionic radius of Mg 2 + leads to limited solubility when alloyed with larger cations such as Sr or Ba. Phase separation observed in such cases indicates a eutectic-like phase diagram. By combining these results with prior alloying studies, we establish an upper limit for cation radius mismatch in A M 2 X 2 alloys to provide general guidance for future alloying and doping studies.
Preparation and Applications of Salt-Resistant Superabsorbent Poly (Acrylic Acid-Acrylamide/Fly Ash) Composite
Authors: Zhu Wenjuan , Zhang Yagang , Wang Penglei , Yang Zhiyong , Yasin Akram , Zhang Letao
Published: February 2019

Solution polymerization synthesized alt-resistant superabsorbent poly (acrylic acid-acrylamide/fly ash) composites. The mass ratio of acrylic acid (AA) to acrylamide (AM), the concentration of crosslinker, the neutralization degree (ND) of AA, and the polymerization temperature were investigated by single-factor method. Optimized conditions for the synthesis of poly (acrylic acid-acrylamide/fly ash) (PAA-AM/FA) are, as following: m (AA)/m (AM) is 1.5, the content of crosslinker N, N-methylenebisacrylamide. (MBA) is 0.7%, neutralization degree of AA is 70%, polymerization temperature is 70 °C, and fly ash (FA) content is 50%. The prepared PAA-AM/FA demonstrated superior water absorption performance. The absorption capacities of PAA-AM/FA for pure water and 0.9% NaCl solution were found to be 976 g·g−1 and 81 g·g−1, respectively. Furthermore, PAA-AM/FA was found to have excellent adsorption capacity (148 mg·g−1) for Rhodamine B in water. Fourier Transform-Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), and Scanning Electron Microscopy (SEM) characterized the prepared materials. Results showed that fly ash was incorporated into the macromolecular polymer matrix and played a key role in improving the performance of the polymer composites.
New Integral Inequalities via the Katugampola Fractional Integrals for Functions Whose Second Derivatives Are Strongly η-Convex
Authors: Kermausuor Seth , Nwaeze Eze , Tameru Ana
Published: February 2019

In this paper, we introduced some new integral inequalities of the Hermite–Hadamard type for functions whose second derivatives in absolute values at certain powers are strongly η -convex functions via the Katugampola fractional integrals.
Comparison of 30-Day MACE between Immediate versus Staged Complete Revascularization in Acute Myocardial Infarction with Multivessel Disease, and the Effect of Coronary Lesion Complexity
Authors: Doğan Cem , Bayram Zübeyde , Çap Murat , Özkalaycı Flora , Unkun Tuba , Erdoğan Emrah , Uslu Abdulkadir , Acar Rezzan Deniz , Guvendi Busra , Akbal Özgur Yaşar , Karagöz Ali , Hakgor Aykun , Karaduman Ahmet , Uysal Samet , Aykan Ahmet , Kaymaz Cihangir , Özdemir Nihal
Published: February 2019

Background and objective: In patients with acute myocardial infarction and multivessel disease, the timing of intervention to non-culprit lesions is still a matter of debate, especially in patients without shock. This study aimed to compare the effect of multivessel intervention, performed at index percutaneous coronary intervention (PCI) (MVI-I) or index hospitalization (MVI-S), on the 30-day results of acute myocardial infarction (AMI), and to investigate the effect of coronary lesion complexity assessed by the Syntax (Sx) score on the timing of multivessel intervention. Materials and methods: We enrolled 180 patients with MVI-I, and 425 patients with MVI-S. The major adverse cardiovascular events (MACE) for this study were identified as mortality, nonfatal myocardial infarction, nonfatal stroke, acute heart failure, ischemia driven revascularization, major bleeding, and acute renal failure developed within 30 days. Results: The unadjusted MACE rates at 30 days were 11.2% and 5% among those who underwent MVI-I and MVI-S, respectively (OR 3.02; 95% confidence interval (CI) 1.51–6.02; p = 0.002). Associations were statistically significant after adjusting for covariates in the penalized multivariable model (adjusted OR 2.06; 95%CI 1.02–4.18; p = 0.043), propensity score adjusted multivariable model (adjusted OR 2.46; 95%CI 1.19–5.07; p = 0.015), and IPW (adjusted OR 2.11; 95%CI 1.28–3.47; p = 0.041). We found that the Syntax score of lesions did not affect the results. Conclusion: MVI-S was associated with a lower incidence of major adverse cardiovascular events within 30 days after discharge.
Is Capacity Building Training Effective for Changing Attitudes toward Health Inequalities? Experience from a Norway Grants Project in Lithuania
Authors: Stankūnas Mindaugas , Kaselienė Snieguolė , Girčienė Akvilė , Tsouros Agis , Avery Mark
Published: February 2019

Background and Objectives: In 2014–2017, the Lithuanian University of Health Sciences and partners implemented the project, ‘Development of the Model for the Strengthening of the Capacities to Identify and Reduce Health Inequalities’, which was financed by The Norwegian Financial Mechanism 2009–2014 Public Health Initiatives Program. One of objectives of this project was to increase the awareness about public health and related specialist knowledge and skills in the field of health inequalities. This paper evaluates the effectiveness of capacity-training sessions on capacity building regarding increasing the awareness and knowledge that is needed for addressing health inequalities. Materials and Methods: Participants attending capacity-building seminars were asked to complete the same questionnaires before and after these training sessions. A total of 145 questionnaires were received (response rate 71.8%). The evaluation of changes in the pre-survey and post-survey responses in relation to a nonparametric analysis of two related samples was performed using the Wilcoxon test. Results: Respondents were asked to identify the general importance of health inequalities to the national public health agenda. The pre-training median of the survey was nine (minimum four; maximum 10), and post-training was 10 [minimum five; maximum 10] (p < 0.001). Unemployed, low-paid, and low-educated people were identified as the most vulnerable groups of society in terms of health inequalities. A more effective tobacco and alcohol control was identified as the most important inequality measure needed. An absolute majority of participants emphasized the need for intersectoral collaboration for the effective reduction of health inequalities. Conclusion: The findings from our study suggest that capacity-building sessions can be effective measures for increasing awareness of health inequalities. It is expected that the outcomes of these training opportunities will act as facilitators for further engagement and ongoing approaches to addressing health inequalities.
Manufacturing and Evaluation of Multi-Material Axial-Bearing Washers by Tailored Forming
Authors: Behrens Bernd-Arno , Chugreev Alexander , Matthias Tim , Poll Gerhard , Pape Florian , Coors Timm , Hassel Thomas , Maier Hans Jürgen , Mildebrath Maximilian
Published: February 2019

Components subject to rolling contact fatigue, such as gears and rolling bearings, are among the fundamental machine elements in mechanical and vehicle engineering. Rolling bearings are generally not designed to be fatigue-resistant, as the necessary oversizing is not technically and economically marketable. In order to improve the load-bearing capacity, resource efficiency and application possibilities of rolling bearings and other possible multi-material solid components, a new process chain was developed at Leibniz University Hannover as a part of the Collaborative Research Centre 1153 “Tailored Forming”. Semi-finished products, already joined before the forming process, are used here to allow a further optimisation of joint quality by forming and finishing. In this paper, a plasma-powder-deposition welding process is presented, which enables precise material deposition and control of the welding depth. For this study, bearing washers (serving as rolling bearing raceways) of a cylindrical roller thrust bearing, similar to type 81212 with a multi-layer structure, were manufactured. A previously non-weldable high-performance material, steel AISI 5140, was used as the cladding layer. Depending on the degree of forming, grain-refinement within the welded material was achieved by thermo-mechanical treatment of the joining zone during the forming process. This grain-refinements lead to an improvement of the mechanical properties and thus, to a higher lifetime for washers of an axial cylindrical roller bearing, which were examined as an exemplary component on a fatigue test bench. To evaluate the bearing washers, the results of the bearing tests were compared with industrial bearings and deposition welded axial-bearing washers without subsequent forming. In addition, the bearing washers were analysed micro-tribologically and by scanning acoustic microscopy both after welding and after the forming process. Nano-scratch tests were carried out on the bearing washers to analyse the layer properties. Together with the results of additional microscopic images of the surface and cross-sections, the causes of failure due to fatigue and wear were identified.
Transmission of Plasticity Through Grain Boundaries in a Metastable Austenitic Stainless Steel
Authors: Mateo Antonio , Sapezanskaia Ina , Roa Joan Josep , Fargas Gemma , Redjaïmia Abdelkrim
Published: February 2019

Austenitic metastable stainless steels have outstanding mechanical properties. Their mechanical behavior comes from the combination of different deformation mechanisms, including phase transformation. The present work aims to investigate the main deformation mechanisms through the grain boundary under monotonic and cyclic tests at the micro- and sub-micrometric length scales by using the nanoindentation technique. Within this context, this topic is relevant as damage evolution at grain boundaries is controlled by slip transfer, and the slip band-grain boundary intersections are preferred crack nucleation sites. Furthermore, in the case of metastable stainless steels, the interaction between martensitic phase and grain boundaries may have important consequences.
Flow Characteristics for Two-Strand Tundish in Continuous Slab Casting Using PIV
Authors: Huang Jun , Yuan Zhigang , Shi Shaoyuan , Wang Baofeng , Liu Chi
Published: February 2019

With the development of continuous casting technology, there has been an increase in the stringent requirements for the cleanliness and quality of steel being produced. The flow state of molten steel in tundish is the key to: Optimizing the residence time of molten steel in the tundish; homogenizing the temperature of molten steel; and removing inclusions by floatation. Hence, from theoretical and practical aspects, it is imperative to examine and analyze the flow field of molten steel in the tundish in order to ensure the desired molten steel flow. In this study, a two-strand tundish with 650 mm × 180 mm slab casting is considered as the subject for this research. According to the similarity theory, combined with the geometrical shape and dimension of the prototype tundish, a tundish model with a geometric similarity ratio of 2:3 is established in the laboratory. Digital particle image velocimetry (PIV) is employed to measure and examine the flow fields at different casting speeds for a tundish containing different flow control devices. The flow in the tundish is typically turbulent and also consists of a vortex motion; it exhibits both random and ordered characteristics. Results reveal that the presence of baffles with 15° holes can cause an upward-directed flow in the outlet section and give rise to a large circulation. When the casting speed is doubled, the overall velocity of the flow field and turbulent intensity increase, leading to an increase in the molten steel surface velocity.
Size Effects of High Strength Steel Wires
Authors: Ono Kanji
Published: February 2019

This study examines the effects of size on the strength of materials, especially on high strength pearlitic steel wires. These wires play a central role in many long span suspension bridges and their design, construction, and maintenance are important for global public safety. In particular, two relationships have been considered to represent strength variation with respect to length parameters: (i) the strength versus inverse square-root and (ii) inverse length equations. In this study, existing data for the strength of high strength pearlitic steel wires is evaluated for the coefficient of determination (R2 values). It is concluded that the data fits into two equations equally well. Thus, the choice between two groups of theories that predict respective relationships must rely on the merit of theoretical developments and assumptions made.
Sn-0.5Cu(-x)Al Solder Alloys: Microstructure-Related Aspects and Tensile Properties Responses
Authors: Lima Thiago Soares , de Gouveia Guilherme Lisboa , da Silva Septimio Rudimylla , da Cruz Clarissa Barros , Silva Bismarck Luiz , Brito Crystopher , Spinelli José Eduardo , Cheung Noé
Published: February 2019

In this study, experiments were conducted to analyze the effect of 0.05 and 0.1 wt.% Al additions during the unsteady-state growth of the Sn-0.5wt.%Cu solder alloy. Various as-solidified specimens of each alloy were selected so that tensile tests could also be performed. Microstructural aspects such as the dimensions of primary, λ1, and secondary, λ2, dendritic arrays, and intermetallic compounds (IMCs) morphologies were comparatively assessed for the three tested compositions, that is, Sn-0.5wt.%Cu, Sn-0.5wt.%Cu-0.05wt.%Al, and Sn-0.5wt.%Cu-0.1wt.%Al alloys. Al addition affected neither the primary dendritic spacing nor the types of morphologies identified for the Cu6Sn5 IMC, which was found to be either globular or fibrous regardless of the alloy considered. Secondary dendrite arm spacing was found to be enlarged and the eutectic fraction was reduced with an increase in the Al-content. Tensile properties remained unaffected with the addition of Al, except for the improvement in ductility of up to 40% when compared to the Sn-0.5wt.%Cu alloy without Al trace. A smaller λ2 in size was demonstrated to be the prime microstructure parameter associated with the beneficial effect on the strength of the Sn-0.5wt.%Cu(-x)Al alloys.
A Microfluidic Micropipette Aspiration Device to Study Single-Cell Mechanics Inspired by the Principle of Wheatstone Bridge
Authors: Li Yong-Jiang , Yang Yu-Nong , Zhang Hai-Jun , Xue Chun-Dong , Zeng De-Pei , Cao Tun , Qin Kai-Rong
Published: February 2019

The biomechanical properties of single cells show great potential for early disease diagnosis and effective treatments. In this study, a microfluidic device was developed for quantifying the mechanical properties of a single cell. Micropipette aspiration was integrated into a microfluidic device that mimics a classical Wheatstone bridge circuit. This technique allows us not only to effectively alter the flow direction for single-cell trapping, but also to precisely control the pressure exerted on the aspirated cells, analogous to the feature of the Wheatstone bridge that can precisely control bridge voltage and current. By combining the micropipette aspiration technique into the microfluidic device, we can effectively trap the microparticles and Hela cells as well as measure the deformability of cells. The Young’s modulus of Hela cells was evaluated to be 387 ± 77 Pa, which is consistent with previous micropipette aspiration studies. The simplicity, precision, and usability of our device show good potential for biomechanical trials in clinical diagnosis and cell biology research.
Subsurface Microbial Hydrogen Cycling: Natural Occurrence and Implications for Industry
Authors: Gregory Simon P. , Barnett Megan J. , Field Lorraine P. , Milodowski Antoni E.
Published: February 2019

Hydrogen is a key energy source for subsurface microbial processes, particularly in subsurface environments with limited alternative electron donors, and environments that are not well connected to the surface. In addition to consumption of hydrogen, microbial processes such as fermentation and nitrogen fixation produce hydrogen. Hydrogen is also produced by a number of abiotic processes including radiolysis, serpentinization, graphitization, and cataclasis of silicate minerals. Both biotic and abiotically generated hydrogen may become available for consumption by microorganisms, but biotic production and consumption are usually tightly coupled. Understanding the microbiology of hydrogen cycling is relevant to subsurface engineered environments where hydrogen-cycling microorganisms are implicated in gas consumption and production and corrosion in a number of industries including carbon capture and storage, energy gas storage, and radioactive waste disposal. The same hydrogen-cycling microorganisms and processes are important in natural sites with elevated hydrogen and can provide insights into early life on Earth and life on other planets. This review draws together what is known about microbiology in natural environments with elevated hydrogen, and highlights where similar microbial populations could be of relevance to subsurface industry.
Investigation of Copper Recovery from a New Copper Deposit (Nussir) in Northern-Norway: Thionocarbamates and Xanthate-Thionocarbamate Blend as Collectors
Authors: Dhar Priyanka , Thornhill Maria , Kota Hanumantha Rao
Published: February 2019

Norway has newly seen an upsurge of interest in exploiting its mineral deposits influenced by fresh Government focus and survey support for previously under-prospected areas. One of the major areas of interest is a huge copper deposit, operated by Nussir ASA, located in the Repparfjord tectonic window in the Caledonides of west Finnmark. The latest mineral resource estimation is from July 2014, which states that Nussir consists of 5.8 million tonnes of indicated resources and 60.2 million tonnes of inferred resources, giving 66 million tonnes of copper ore. This paper represents the first study on processing characteristics of this ore to date. Our parallel studies using xanthates and dithiophosphates as collectors for Nussir ore flotation examined the grade and recovery of copper, silver, gold, and platinum group (PGM) minerals. Therefore, in this subsequent study, a chelating agent n-Butoxycarbonyl-O-n-butyl thionocarbamate (BBT) is used as a collector and it was found that the recovery and grades of the economically interesting minerals are improved at as low as 2 × 10−5 M collector concentration. Zeta potential, Hallimond flotation and adsorption studies were initially performed in order to assess the selective interaction of BBT and its blend with SIBX (Sodium Isobutyl xanthate) on the three copper minerals of the ore. The bench scale flotation experiments were performed using mixtures of xanthate and thionocarbamate collectors of the Nussir ore and both the resulting copper recovery and grade employing these collector mixtures is observed to be 2–8% superior to the use of a single collector system. Additionally, the current study revealed that the metallurgical results are strongly influenced by the ratio of the collectors in the mixture and particularly the sequence of the collector addition.
Anti-α-Glucosidase Activity by a Protease from Bacillus licheniformis
Authors: Doan Chien Thang , Tran Thi Ngoc , Nguyen Minh Trung , Nguyen Van Bon , Nguyen Anh Dzung , Wang San-Lang
Published: February 2019

Anti-α-glucosidase (AAG) compounds have received great attention due to their potential use in treating diabetes. In this study, Bacillus licheniformis TKU004, an isolated bacterial strain from Taiwanese soil, produced AAG activity in the culture supernatant when squid pens were used as the sole carbon/nitrogen (C/N) source. The protein TKU004P, which was isolated from B. licheniformis TKU004, showed stronger AAG activity than acarbose, a commercial anti-diabetic drug (IC50 = 0.1 mg/mL and 2.02 mg/mL, respectively). The molecular weight of TKU004P, determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), was 29 kDa. High-performance liquid chromatography (HPLC) analysis showed that TKU004P may be a protease that demonstrates AAG activity by degrading yeast α-glucosidase. Among the four chitinous sources of C/N, TKU004P produced the highest AAG activity in the culture supernatant when shrimp head powder was used as the sole source (470.66 U/mL). For comparison, 16 proteases, were investigated for AAG activity but TKU004P produced the highest levels. Overall, the findings suggest that TKU004P could have applications in the biochemical and medicinal fields thanks to its ability to control the activity of α-glucosidase.
Electrochemical Umpolung of Bromide: Transition-Metal-Free Bromination of Indole C–H Bond
Authors: Zhang Pan , Chen Jianbin , Gao Wei , Xiao Yiting , Liu Changwei , Xu Shanghui , Yan Xiaoli , Qin Dawei
Published: February 2019

A facile and sustainable electrochemical umpolung of bromide ion protocol was developed under mild reaction conditions. Transition metal catalysts and exogenous chemical oxidants were obviated for the bromination of C–H bond. Notably, graphite rod, which is commercially available at supermarkets and is inexpensive, was employed as the electrode material. This operationally easy and environmentally friendly approach accomplished the synthesis of 3-bromoindole in excellent yield and regioselectivity.
Phytochemical Profiling of Coryphantha macromeris (Cactaceae) Growing in Greenhouse Conditions Using Ultra-High-Performance Liquid Chromatography–Tandem Mass Spectrometry
Authors: Cabañas-García Emmanuel , Areche Carlos , Jáuregui-Rincón Juan , Cruz-Sosa Francisco , Pérez-Molphe Balch Eugenio
Published: February 2019

Chromatographic separation combined with mass spectrometry is a powerful tool for the characterization of plant metabolites because of its high sensitivity and selectivity. In this work, the phytochemical profile of aerial and radicular parts of Coryphantha macromeris (Engelm.) Britton & Rose growing under greenhouse conditions was qualitatively investigated for the first time by means of modern ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC-PDA-HESI-Orbitrap-MS/MS). The UHPLC-PDA-HESI-Orbitrap-MS/MS analysis indicated a high complexity in phenolic metabolites. In our investigation, 69 compounds were detected and 60 of them were identified. Among detected compounds, several phenolic acids, phenolic glycosides, and organic acids were found. Within this diversity, 26 metabolites were exclusively detected in the aerial part, and 19 in the roots. Twenty-four metabolites occurred in both plant parts. According to the relative abundance of peaks in the chromatogram, ferulic and piscidic acids and their derivatives may correspond to one of the main phenolic compounds of C. macromeris. Our results contribute to the phytochemical knowledge regarding C. macromeris and its potential applications in the pharmaceutical and cosmetic industries. Besides, some metabolites and their fragmentation patterns are reported here for the first time for cacti species.
Newly Synthesized Oxygenated Xanthones as Potential P-Glycoprotein Activators: In Vitro, Ex Vivo, and In Silico Studies
Authors: Martins Eva , Silva Vera , Lemos Agostinho , Palmeira Andreia , Puthongking Ploenthip , Sousa Emília , Rocha-Pereira Carolina , Ghanem Carolina I. , Carmo Helena , Remião Fernando , Silva Renata
Published: February 2019

P-glycoprotein (P-gp) plays a crucial role in the protection of susceptible organs, by significantly decreasing the absorption/distribution of harmful xenobiotics and, consequently, their toxicity. Therefore, P-gp has been proposed as a potential antidotal pathway, when activated and/or induced. Knowing that xanthones are known to interact with P-gp, the main goal was to study P-gp induction or/and activation by six new oxygenated xanthones (OX 1-6). Furthermore, the potential protection of Caco-2 cells against paraquat cytotoxicity was also assessed. The most promising compound was further tested for its ability to increase P-gp activity ex vivo, using everted intestinal sacs from adult Wistar-Han rats. The oxygenated xanthones interacted with P-gp in vitro, increasing P-gp expression and/or activity 24 h after exposure. Additionally, after a short-incubation period, several xanthones were identified as P-gp activators, as they immediately increased P-gp activity. Moreover, some xanthones decreased PQ cytotoxicity towards Caco-2 cells, an effect prevented under P-gp inhibition. Ex vivo, a significant increase in P-gp activity was observed in the presence of OX6, which was selectively blocked by a model P-gp inhibitor, zosuquidar, confirming the in vitro results. Docking simulations between a validated P-gp model and the tested xanthones predicted these interactions, and these compounds also fitted onto previously described P-gp induction and activation pharmacophores. In conclusion, the in vitro, ex vivo, and in silico results suggest the potential of some of the oxygenated xanthones in the modulation of P-gp, disclosing new perspectives in the therapeutics of intoxications by P-gp substrates.
Analysis of Metabolite Accumulation Related to Pod Color Variation of Caragana intermedia
Authors: Yang Feiyun , Yang Tianrui , Liu Kun , Yang Qi , Wan Yongqing , Wang Ruigang , Li Guojing
Published: February 2019

Caragana intermedia, a leguminous shrub widely distributed in cold and arid regions, is rich in secondary metabolites and natural active substances, with high nutritional and medical values. It is interesting that the pods of C. intermedia often show different colors among individual plants. In this study, 10-, 20- and 30-day-old red and green pods of C. intermedia were used to identify and characterize important metabolites associated with pod color. A total 557 metabolites, which could be classified into 21 groups, were detected in the pod extracts using liquid chromatography coupled with ESI-triple quadrupole-linear ion trap mass spectrometer (LC-ESI-MS/MS). Metabolomics analysis revealed significant differences in 15 groups of metabolites between red and green pods, including amino acids, nucleotide derivatives, flavonoids, and phytohormones. Metabolic pathway analysis showed that the shikimic acid and the phytohormone metabolic pathways were extraordinarily active in red pods, and the difference between red and green pods was obvious. Moreover, red pods showed remarkable flavonoids, cytokinins, and auxin accumulation, and the content of total flavonoids and proanthocyanidins in 30-day-old red pods was significantly higher than that in green pods. This metabolic profile contributes to valuable insights into the metabolic regulation mechanism in different color pods.
Acylated Flavonoid Glycosides are the Main Pigments that Determine the Flower Colour of the Brazilian Native Tree Tibouchina pulchra (Cham.) Cogn.
Authors: Rezende Fernanda Mendes , Ferreira Marcelo José Pena , Clausen Mads Hartvig , Rossi Magdalena , Furlan Claudia Maria
Published: February 2019

Tibouchina pulchra (Cham.) Cogn. is a plant native to Brazil whose genus and family (Melastomataceae) are poorly studied with regards to its metabolite profile. Phenolic pigments of pink flowers were studied by ultra-performance liquid chromatography with a photodiode array detector and electrospray ionization quadrupole time-of-flight mass spectrometry. Therein, twenty-three flavonoids were identified with eight flavonols isolated by preparative high-performance liquid chromatography and analysed by one- and two-dimensional nuclear magnetic resonance. Kaempferol derivatives were the main flavonols, encompassing almost half of the detected compounds with different substitution patterns, such as glucoside, pentosides, galloyl-glucoside, p-coumaroyl-glucoside, and glucuronide. Concerning the anthocyanins, petunidin p-coumaroyl-hexoside acetylpentoside and malvidin p-coumaroyl-hexoside acetylpentoside were identified and agreed with previous reports on acylated anthocyanins from Melastomataceae. A new kaempferol glucoside was identified as kaempferol-(2′′-O-methyl)-4′-O-α-d-glucopyranoside. Moreover, twelve compounds were described for the first time in the genus with five being new to the family, contributing to the chemical characterisation of these taxa.
Amylase and Xylanase from Edible Fungus Neurospora intermedia: Production and Characterization
Authors: Shahryari Zohre , Fazaelipoor Mohammad H. , Ghasemi Younes , Lennartsson Patrik R. , Taherzadeh Mohammad J.
Published: February 2019

Integrated enzyme production in the biorefinery can significantly reduce the cost of the entire process. The purpose of the present study is to evaluate the production of two hydrolyzing enzymes (amylase and xylanase) by an edible fungus used in the biorefinery, Neurospora intermedia. The enzyme production was explored through submerged fermentation of synthetic media and a wheat-based waste stream (thin stillage and wheat bran). The influence of a nitrogen source on N. intermedia was investigated and a combination of NaNO3 and yeast extract has been identified as the best nitrogen source for extracellular enzyme production. N. intermedia enzymes showed maximum activity at 65 °C and pH around 5. Under these conditions, the maximum velocity of amylase and xylanase for starch and xylan hydrolysis was found to be 3.25 U mL−1 and 14.77 U mL−1, respectively. Cultivation of N. intermedia in thin stillage and wheat bran medium resulted in relatively high amylase (8.86 ± 0.41 U mL−1, 4.68 ± 0.23) and xylanase (5.48 ± 0.21, 2.58 ± 0.07 U mL−1) production, respectively, which makes this fungus promising for enzyme production through a wheat-based biorefinery.
Microparticles of Lamivudine—Poly-ε-Caprolactone Conjugate for Drug Delivery via Internalization by Macrophages
Authors: Urbaniak Tomasz , Machová Daniela , Janoušková Olga , Musiał Witold
Published: February 2019

The past decade may be considered as revolutionary in the research field focused on the physiological function of macrophages. Unknown subtypes of these cells involved in pathological mechanisms were described recently, and they are considered as potential drug delivery targets. The innate ability to internalize foreign bodies exhibited by macrophages can be employed as a therapeutic strategy. The efficiency of this uptake depends on the size, shape and surface physiochemical properties of the phagocyted objects. Here, we propose a method of preparation and preliminary evaluation of drug-polymer conjugate-based microspheres for macrophage targeted drug delivery. The aim of the study was to identify crucial uptake-enhancing parameters for solid, surface modified particles. A model drug molecule—lamivudine—was conjugated with poly-ε-caprolactone via ring opening polymerization. The conjugate was utilized in a solvent evaporation method technique to form solid particles. Interactions between particles and a model rat alveolar cell line were evaluated by flow cytometry. The polymerization product was characterized by a molecular weight of 3.8 kDa. The surface of the obtained solid drug-loaded cores of a hydrodynamic diameter equal to 2.4 µm was modified with biocompatible polyelectrolytes via a layer-by-layer assembly method. Differences in the internalization efficiency of four particle batches by the model RAW 264.7 cell line suggest that particle diameter and surface hydrophobicity are the most influential parameters in terms of phagocytic uptake.
Preparation and Characterization of TiO2-PVDF/PMMA Blend Membranes Using an Alternative Non-Toxic Solvent for UF/MF and Photocatalytic Application
Authors: Benhabiles Ouassila , Galiano Francesco , Marino Tiziana , Mahmoudi Hacene , Lounici Hakim , Figoli Alberto
Published: February 2019

The approach of the present work is based on the use of poly (methylmethacrylate) (PMMA) polymer, which is compatible with PVDF and TiO2 nanoparticles in casting solutions, for the preparation of nano-composites membranes using a safer and more compatible solvent. TiO2 embedded poly (vinylidene fluoride) (PVDF)/PMMA photocatalytic membranes were prepared by phase inversion method. A non-solvent induced phase separation (NIPS) coupled with vapor induced phase separation (VIPS) was used to fabricate flat-sheet membranes using a dope solution consisting of PMMA, PVDF, TiO2, and triethyl phosphate (TEP) as an alternative non-toxic solvent. Membrane morphology was examined by scanning electron microscopy (SEM). Backscatter electron detector (BSD) mapping was used to monitor the inter-dispersion of TiO2 in the membrane surface and matrix. The effects of polymer concentration, evaporation time, additives and catalyst amount on the membrane morphology and properties were investigated. Tests on photocatalytic degradation of methylene blue (MB) were also carried out using the membranes entrapped with different concentrations of TiO2. The results of this study showed that nearly 99% MB removal can be easily achieved by photocatalysis using TiO2 immobilized on the membrane matrix. Moreover, it was observed that the quantity of TiO2 plays a significant role in the dye removal.
Campylobacter Phage Isolation and Characterization: What We Have Learned So Far
Authors: Jäckel Claudia , Hammerl Jens Andre , Hertwig Stefan
Published: February 2019

Lytic Campylobacter phages, which can be used to combat this pathogen in animals and on food products, have been studied for more than 30 years. Though, due to some peculiarities of the phages, which hampered their isolation and particularly their molecular analysis for a long time, progress in this research field was rather slow. Meanwhile, the situation has changed and much more is known about the biology and genetics of those phages. In this article, we address specific issues that should be considered when Campylobacter phages are studied, starting with the isolation and propagation of the phages and ending with a thorough characterization including whole-genome sequencing. The basis for advice and recommendations given here is a careful review of the scientific literature and experiences that we have had ourselves with Campylobacter phages.
Protocol for Construction of Rat Nerve Stimulation Cuff Electrodes
Authors: Rios Manolo U. , Bucksot Jesse E. , Rahebi Kimiya C. , Engineer Crystal T. , Kilgard Michael P. , Hays Seth A.
Published: February 2019

Peripheral nerve stimulation has emerged as a platform therapy to treat a wide range of disorders. Continued development and translation of these strategies requires that researchers have access to reliable, customizable electrodes for nerve stimulation. Here, we detail procedures to build three different configurations of cuff electrodes with varying numbers and orientations of contacts for nerve stimulation in rats. These designs are built with simple, widely available materials, using platinum–iridium electrodes assembled into polyurethane tubing. Moreover, the designs can easily be customized to increase versatility and individualize for specific stimulation applications. This protocol provides a resource to facilitate the construction and customization of stimulation cuffs to support preclinical nerve stimulation research.
Preparation of N-Doped Carbon Nanosheets from Sewage Sludge for Adsorption Studies of Cr(VI) from Aqueous Solution
Authors: Wang Yi , Zhao Weinan , Zheng Wanlan , Chen Shuang , Zhao Jinsheng
Published: February 2019

Porous activated carbon with specific morphology and structure are of particular importance for waste water treatment, especially for the adsorption of toxic hexavalent chromium Cr(VI). However, the scalable and cheap production of such absorbents still suffer a grand challenge. Herein, a new type of N-doped nanosheet was innovatively prepared from easily available and low-cost sewage sludge via a facile and recyclable KOH activation method. The N-doped porous carbon nanosheets (N-SAC) produced by introduction of KOH and dicyandiamide, which performed favourable features for metal ions adsorption (93.2% for Cr(VI)) due to its high specific surface area, tuneable pore size distributions and good hydrophilicity. Additionally, the capacity also remained high after two cycles of adsorption by thermal regeneration, with 90.8% removal rate. The DFT calculation also approved that the doping of N could optimize the Mulliken charges distribution and improve the HOMO energy and improve the adsorption ability of N-SAC. This original proposal may inspire new possibility of creating porous carbon absorbents in a recyclable method.
Tunable Electronic Properties of Nitrogen and Sulfur Doped Graphene: Density Functional Theory Approach
Authors: Lee Ji Hye , Kwon Sung Hyun , Kwon Soonchul , Cho Min , Kim Kwang Ho , Han Tae Hee , Lee Seung Geol
Published: February 2019

We calculated the band structures of a variety of N- and S-doped graphenes in order to understand the effects of the N and S dopants on the graphene electronic structure using density functional theory (DFT). Band-structure analysis revealed energy band upshifting above the Fermi level compared to pristine graphene following doping with three nitrogen atoms around a mono-vacancy defect, which corresponds to p-type nature. On the other hand, the energy bands were increasingly shifted downward below the Fermi level with increasing numbers of S atoms in N/S-co-doped graphene, which results in n-type behavior. Hence, modulating the structure of graphene through N- and S-doping schemes results in the switching of “p-type” to “n-type” behavior with increasing S concentration. Mulliken population analysis indicates that the N atom doped near a mono-vacancy is negatively charged due to its higher electronegativity compared to C, whereas the S atom doped near a mono-vacancy is positively charged due to its similar electronegativity to C and its additional valence electrons. As a result, doping with N and S significantly influences the unique electronic properties of graphene. Due to their tunable band-structure properties, the resulting N- and S-doped graphenes can be used in energy and electronic-device applications. In conclusion, we expect that doping with N and S will lead to new pathways for tailoring and enhancing the electronic properties of graphene at the atomic level.