bluuebunny/crossref_metadata_2025 huggingface dataset:
Waiting for Breakthrough in Conventional Submarine’s Prime Movers
Authors: Lus Tomasz
Published: April 2019

Submarines, as a very expensive and sophisticated type of weaponry, are being intensively exploited by the armed forces of many countries. This means that submarines are sent ever longer patrols, sometimes to distant regions. To meet such requirements, submarine sub-systems and components must have high reliability and operational readiness indicators. Among the many machines and devices found on submarines, the ones that generate, store, and consume energy (mainly electricity) deserve special attention. The largest energy consumers on the submarine are the components of its propulsion system. One of the most complicated and loaded devices on board submarine is a power generator with a diesel engine driving it, on whose continuous and reliable work the safe performance of tasks depends. According to statistical research, despite its importance for the process of performing tasks by submarines, diesel engines are still the least reliable devices on submarines. Despite the constant technological development of piston engines, their work in very difficult conditions under heavy load and at high counter-pressure at the exhaust outlet promotes their malfunction and damage. From this point of view, the development of charge air systems for submarine diesel engines based on the construction experience of MTU Company is described in the paper. The classification of submarines, their propulsion systems, and the working conditions of engines on submarines are presented in the paper. Air-Independent Propulsion (AIP) systems with their applications on chosen submarines are also described. The most significant change in submarine propulsion system observed in 2018, transition from lead-acid to lithium-ion batteries, is also presented.
Concept and First Results of Optical Navigational System
Authors: Praczyk Tomasz , Hożyń Stanisław , Bodnar Tadeusz , Pietrukaniec Leszek , Błaszczyk Marek , Zabłotny Michał
Published: April 2019

The paper presents a concept of the optical coastal navigational system. The task of the system is to provide information about object position in coastal areas based on optical information. The system is intended for Autonomous Underwater Vehicles that operate in GPS denied environments. In addition to the concept itself, the paper also outlines the first results achieved during the research on the system.
Preliminary Calculations for Minehunter's Genset Foundations
Authors: Grządziela Andrzej , Kluczyk Marcin
Published: April 2019

The requirements for the foundations of naval vessel engines are based on classification rules devised by classification societies or/and military standardization rules. A class guideline was published, defining the requirements, acceptance criteria and machinery seating methods. There is also a schedule of basic calculation procedures for cast resin or rubber chocks which facilitates the process of machinery foundation design, preloading force calculation, the establishment of boundary conditions etc. In case of naval vessels, typical procedures do not meet tactical requirements due to potential explosion loads. Since minehunters are mainly deployed at sea, handling active, naval mines, the shock resistance calculation for the entire machinery, including the Genset, is required. The paper presents preliminary MatLab calculation methods which can be used to analyse the type, number and location of rubber or elastomer chocks. The procedure consists of input data such as UNDEX pressure and technical data of the Genset used in the Polish Navy. Calculation results include the analysis of the dynamic interaction between the Genset and the foundation, as well as the damping effect generated by the UNDEX (UNDerwater EXplosion) shock pulse.
Seafarer Market – Challenges for the Future
Authors: Lušić Zvonimir , Bakota Mario , Čorić Mirko , Skoko Ivica
Published: April 2019

In the today’s seafarer market one of the key problems is the lack of seafarers, especially experienced officers. Although the global supply of officers is increasing steadily, the demand is still above supply. An additional problem is that an increased demand may lead to a decreased quality of education. Ships and shipping technology in general have become more advanced and require well educated and trained personnel. In addition, over the next several decades it is expected that partial or fully autonomous vessels will be in commercial use, and this will require significant changes in the education and training of crew members. So, regarding the education of seafarers, the main future challenges include the ways of ensuring sufficient supply of seafarers, especially well-trained officers, and adapting the education systems for the upcoming introduction of autonomous ships. This paper analyzes the present situation of the seafarers and shipping market, and provides forecast for the near future. Also, the main challenges in education and training of seafarers will refer to observing the recommendations for improvement and adaptation to future demands.
Friction Stir Welding for Marine Applications: Mechanical Behaviour and Microstructural Characteristics of Al-Mg-Si-Cu Plates
Authors: Roldo Liane , Vulić Nenad
Published: April 2019

Friction stir welding is a multipurpose solid-state joining process mainly used for aluminium and steel plates and frames. Friction stir welded non-ferrous metallic alloys, similar or dissimilar, in particular aluminium alloys, provide opportunities for the improvement and developement of new product designs. This paper investigates the correlation between the mechanical behaviour and morphological structures of friction stir welded Al-Mg-Si(Cu) alloy plates in two temper conditions. Micro Vickers hardness and tensile tests were carried out. Additionally, morphology was investigated using optical microscopy and scanning electron microscopy. Samples subjected to the post weld heat treatment were shown to have the best properties owing to the formation of a significant number of hardening particles which, added to the nugget grain refinement, resulted in the increase of the material strength.
Maritime and Other Key Transport Issues for the Future – Education and Training in the Context of Lifelong Learning
Authors: Edler Jeannette , Infante Virginia
Published: April 2019

The entire transport system will transform into an integrated transport system in response to future trends and demands. The EU Skilful project defines the impact on job profiles across all transport modes and at all levels of work and duties. Changing and emerging job profiles require training which on the one hand makes use of the latest training and education methods, while on the other meeting the need for the acquisition of special competencies, skills and abilities. The demand for individualization of training contents will soar in the interlinked global world and integrated transport systems.

An additional questionnaire was conducted in the spring of 2018, in the assessment of the maritime and transport sectors. The answers of course lecturers and organisers concerning present and future needs and lifelong learning issues were instructive, with most of the people having concrete ideas about lifelong learning.

Courses will therefore include future oriented contents, a practicable registration procedure with information for qualified trainers capable of tailoring course contents to the specific focus of the course and participants’ requirements, giving excellent lectures with relevant learning material and real usable factors, clear structure, practical parts, remarks of concrete relevance, communication parts for improving soft skills, experience exchange and learning from other participants, intercultural aspects for globalization, reconciling mixed group needs and requirements and learning to learn methods, using different adult suitable methods and finally focusing on emotions to capitalize on the motivation to learn.

Lifelong learning is a key issue for successful employers and employees.
Satellite Derived Bathymetry Survey Method - Example of Hramina Bay
Authors: Duplančić Leder Tea , Leder Nenad , Peroš Josip
Published: April 2019

Satellite Derived Bathymetry (SDB) method uses satellite or other remote multispectral imagery for depth determination in very shallow coastal areas with clear waters. Commonly, SDB survey method can be used when planning hydrographic surveying of marine areas not surveyed or areas with old bathymetric data. This method has become widely used in the past few years. SDB is a survey method founded on analytical modelling of light penetration through the water column in visible and infrared bands. In this article, SDB method was applied by using free-of-charge Landsat 8 and Sentinel 2 satellite images to get the bathymetric data in the area of Hramina Bay in the Central Adriatic. SDB processing procedures and algorithms were described. Processed satellite data was uploaded on geodetic software and ENC S-57 format. The bathymetric map of Hramina Bay obtained by the SDB method was compared with the approach usage band Electronic Nautical Chart (ENC) HR400512 with satisfying positional and vertical accuracy.
Marina Operator Liability Insurance in Croatian and Slovenian Law and Practice
Authors: Padovan Adriana Vincenca , Selan Voglar Margita
Published: April 2019

The paper deals with marina operator liability insurance (hereinafter: MOLI) in the context of Croatian and Slovenian insurance law and business practice. The authors analyse, discuss and compare the salient features of MOLI contracts, their standard terms and conditions, scope of coverage and exclusions in Croatian and Slovenian law. The paper describes the relevant business practice in the two Adriatic countries. The analysis is based on the comparative study of the relevant national legislation and private regulation, as well as on the data and documentation gathered by field research, consisting of written questionnaires and live interviews with the representatives of insurance companies and marina operators. Our thesis is that the legal framework in the two observed jurisdictions, as well as the insurers’ private regulation in Croatia and Slovenia are very similar. The aim is to establish the common features of MOLI contracts and of the related practices of marina operators and their insurers in the respective countries and explain the background that has led to the formation of a MOLI product specific for the eastern Adriatic marina industry. Suggestions are given for the improvement of the relevant business practices and administrative requirements regarding the minimum insurance standards imposed on marina operators by the concessioning process.
Can Marina Qualify as a Place of Refuge?
Authors: Petrinović Ranka , Mandić Nikola
Published: April 2019

This paper deals with marinas as potential places of refuge. A place of refuge is a port, a part of a port, a sheltered wharf or anchorage, or another sheltered area where temporary accommodation of vessels and marine facilities is possible in order to render assistance or avoid potential threats to humans, ships and the environment. Marinas, as the most important type of nautical port, are suitable for smaller vessels. In countries like the Republic of Croatia, where the development of nautical tourism is of great importance, the obligation of marinas to provide assistance or grant access to ships in distress needs to be established. Thereby, it is essential to take into account all marina characteristics and compare them with those of other types of ports. In Croatian legislation, places of refuge are regulated by the Ordinance on Places of Refuge compliant with IMO Guidelines A.949 (23) and A.950 (23) and European Directives (2002/59 / EC). The paper analyses the suitability of the marinas as places of refuge for vessels, primarily vessels for nautical tourism.
Maritime Cyber Security Analysis – How to Reduce Threats?
Authors: Mraković Ivan , Vojinović Ranko
Published: April 2019

Maritime cyber security management requires a holistic approach as there is an increase in complexity, digitalization, and automation of systems in maritime industry. Numerous interconnected systems between ship and shore, which are in need of a special focus in the internet environment, are increasing on daily basis. Nowadays one of the major concerns in maritime computing is vulnerability to cyber-attacks. In maritime industry, cyber incidents can lead to loss of life, loss of control over ships or sensitive data, as well as ship and/or cargo hijacking. This paper therefore covers key problems of maritime industry from cyber security perspective and proposes solutions on how to eliminate or minimize them.
Exploring the sirtuin functionality in aging through the human protein interaction networks
Authors: Nahálková Jarmila
Published: April 2019

The sirtuin family contains seven proteins with the functions in multiple diseases of aging, which makes them an attractive subject for the development of therapies of age-related diseases and anti-aging treatments. The primary objective of the protein-interaction network analysis presented here is to identify the signaling pathways and protein nodes driving the functions of the sirtuins. For this purpose, the protein-protein interaction data were collected from the available public databases, which fulfilled the quality threshold and included at least one member of the sirtuin family. The databases provided 66 interactions validated by several experiments, which were further processed by the bioinformatic tools connected to the integrated genomic, proteomic, and pharmacologic data. The interactions were analyzed by the pathway enrichment, the gene function prediction analysis, and the protein node prioritization by use of Cytoscape applications GeneMania and Cytohubba. The constructed sirtuin protein interaction network (SPIN) contained after the extension 98 protein nodes. TGFβ, PTK2, CARM1, Notch signaling and the pathways regulating androgen and estrogen levels, significantly scored in the pathway enrichment analysis of SPIN. The enriched signaling pathways mediating the pleiotropic effects of the sirtuin family, play the roles in several age-related diseases probably. The Cytohubba application has highlighted the function of HDAC1, EP300, SMAD4, MYC, SIN3A, RBBP4, HDAC, SIN3B, RBBP7 and SMAD3 as the high priority protein nodes driving the molecular functions of SPIN. The presented protein interaction study provide new understandings of the sirtuin functions in the longevity and diseases of aging including cancer, neurodegenerative and metabolic disorders.
Site selection by geese in a suburban landscape
Authors: Groom Quentin J , Adriaens Tim , Delhez Pauline , Van Der Beeten Iris
Published: April 2019

Background

In northern European and North American cities geese are one of the commonest and most visible large herbivores that inhabit the suburban environment . As such, their presence and behavior often conflicts with the desires of the human residents. Fouling, noise, aggression and health concerns are all cited as reasons that there are “too many”. Lethal control is often used for control, however, this raises questions about whether this is a sustainable strategy to resolve the conflict between humans and geese, when paradoxically, it is humans that are responsible for creating the habitat and often providing the food and protection of geese at other times. We hypothesis that the landscaping of suburban parks can be improved to decrease its attractiveness to geese and to reduce the opportunity for conflict between geese and humans.

Methods.

Using observations collected over five years from a botanic garden situated in suburban Belgium and data from the whole of Flanders in Belgium we examine landscape features that attract geese, including the presence of islands in lakes, the distance from water, barriers to level flight and the size of grazing areas. The birds studied were the tadornine goose Alopochen aegyptiaca (L. 1766) (Egyptian geese) and the anserine geese, Branta canadensis (L. 1758) (Canada geese), Anser anser (L. 1758) (greylag geese) and Branta leucopsis (Bechstein, 1803) (barnacle geese). Landscape modification is a known method for modifying geese behavior, but there is little information on the power of such methods with which to inform managers and planners.

Results.

Our results demonstrate that lakes with islands attract more than twice as many anserine geese, than lakes without island, but make little difference to Egyptian geese. Furthermore, flight barriers between grazing areas and lakes are an effective deterrent to geese using an area for feeding. Keeping grazing areas small and surrounded by trees reduces their attractiveness to geese.

Conclusion.

The results suggest that landscape design can be used successfully to reduce the number of geese and their conflict with humans. However, this approach has its limitations and would require humans to compromise on what they expect from their landscaped parks, such as open vistas, lakes and closely cropped lawns.
„Wort des Jahres Schweiz“ als Ergebnis systematischer Diskursmessung im mehrsprachigen Kontext
Authors: Liste Lamas Elsa
Published: April 2019

This paper provides an overview of what the Word of the Year in Switzerland was, is and will be. It first introduces the different Swiss Word of the Year initiatives and then discusses the transition process from the former CH-Wort des Jahres to the new project Word of the Year Switzerland, carried out by the Zurich University of Applied Sciences. Both new and prospective developments in the selection process will be presented in more detail.
Shared behavioral mechanisms underlie C. elegans aggregation and swarming
Authors: Ding Siyu Serena , Schumacher Linus J , Javer Avelino E , Endres Robert G , Brown André EX
Published: April 2019

In complex biological systems, simple individual-level behavioral rules can give rise to emergent group-level behavior. While collective behavior has been well studied in cells and larger organisms, the mesoscopic scale is less understood, as it is unclear which sensory inputs and physical processes matter a priori. Here, we investigate collective feeding in the roundworm C. elegans at this intermediate scale, using quantitative phenotyping and agent-based modeling to identify behavioral rules underlying both aggregation and swarming—a dynamic phenotype only observed at longer timescales. Using fluorescence multi-worm tracking, we quantify aggregation in terms of individual dynamics and population-level statistics. Then we use agent-based simulations and approximate Bayesian inference to identify three key behavioral rules for aggregation: cluster-edge reversals, a density-dependent switch between crawling speeds, and taxis towards neighboring worms. Our simulations suggest that swarming is simply driven by local food depletion but otherwise employs the same behavioral mechanisms as the initial aggregation.
Assessing reproducibility in association studies
Authors: Schnack Hugo
Published: April 2019

Research that links brain structure with behavior needs more data, better analyses, and more intelligent approaches.
Facilitators and barriers to education for chiropractic students with visual impairment
Authors: Joshi Aditi , Ray Suzanne L.
Published: April 2019

Objective

The purpose of this study was to document the academic experiences of students with visual impairment in a doctor of chiropractic program.

Methods

Ten participants were recruited, including 3 students who are “legally blind,” 2 student notetakers, 3 faculty members who taught students with visual impairment, and 2 staff members from the Disability Services Office. For this qualitative study, the students were recruited through the Disability Services Office. The participants were audiotaped during approximately 1-hour interviews conducted in a semistructured manner within a private setting (a quiet office) on the campus during office hours. Thematic analysis was conducted using a deductive method for codes and an inductive method for themes.

Results

We identified facilitators and barriers to the education of students with visual impairment. Notable facilitators were planning for accessible educational materials, accessibility of workable space, and support systems, such as notetakers and close interaction with faculty. Notable barriers were attitudes of students with visual impairment toward their education, lack of personnel training, and lack of disability awareness in the campus community.

Conclusion

Meticulous planning of resources and communication are key to enriching academic experiences of students with visual impairment.
Effect of Different Combinations of NPK and Biofertilizers on Zinnia (Zinnia elegans J.)
Authors: Slathia Divya , Khan F. U. , Masoodi N. H. , Khan F. A. , Wani J. A. , Iqbal Umar , . Neelofar , . Madinat-Ul-Nisa , . Tanzeela
Published: April 2019

The experiment was carried out to study the effect of different combinations of NPK and biofertilizers on zinnia (Zinnia elegans J.) at SKUAST – K, Shalimar, Srinagar, Jammu and Kashmir. The experiment was laid out in Randomised Block Design with three replications. The experiment consist of three levels of chemical fertilizers (NPK @ 28:16:10, 21:12:7.5, and 14:8:5 g/m2) along with different combinations of biofertilizers [Azotobacter, PSB (Phosphorous Solubilizing Bacteria), KSB (Potassium Solubilizing Bacteria), Azotobacter + PSB, Azotobacter + PSB + KSB]. The results revealed that treatment combination of (NPK 21:12:7.5 g/m2 + Azotobacter + PSB + KSB) recorded maximum plant height (125.32 cm), number of primary branches (9.73), plant spread (66.55 cm2), minimum days taken to anthesis (48.88 days), maximum flowering duration (42.42 days), seed yield per plant (21.19 g) respectively compared to control.
Towards an Integrative Psychological Model for Climate Change Mitigation Behavior among Managers in the Tourism Industry
Authors: Kinyanjui D. N.
Published: April 2019

The aims of the current paper are to provide an extensive review of the theoretical and empirical evidence on which current climate change mitigation efforts are based and to advance a new model of the determinants of mitigation behavior. The study was based on the review of relevant literature. The model specifically demonstrates the interplay between human values, attitude, knowledge, emotions and social norms as determinants of broad and greater levels of mitigation behaviours. The model is complemented by adding age and sex as confounders. It indicates the possible interrelationships between these factors with their joint effects being emphasized.

The model addresses a concern that most business-level climate change policies ought to be integrative, but are unfortunately, not. Detailed knowledge of psychological determinants is useful for policy makers to provide favorable conditions in support of business level climate change mitigation measures and how it can be used to measure and compare the impacts of the determinants so as to generate more applicable mitigation measures in  optimizing climate change policies now and in the future.
Security Agents and Elections Security in the 2015 Nigeria’s General Elections
Authors: Olutola Olajire O.
Published: April 2019

Election security has been identified as a salient condition for the orderly and effective administration of elections. Unfortunately, the inability of security agents to offer election security in a competent, independent and professional manner, with due recourse to the rule of law particularly respect for the fundamental human rights of the electorates has been seen as one of the fundamental cogs in the wheels of election security in Nigeria. Based on the foregoing, this paper critically examined the role of security agents in the conduct of 2015 elections in Nigeria. Relying mainly on secondary sources of data collection, the paper described how a notable departure from the past was noticeable in the conduct of security agents during the 2015 elections. While the paper concludes that there is room for significant improvement and a positive change, it canvases sincere, purposeful and determined commitment from the central government to make this realisable.
An Efficient One‐Pot Enzymatic Synthesis of Cardiac Glycosides with Varied Sugar Chain Lengths
Authors: Huang Wei , Wen Chao , Zhou Zhen‐Ru , Fu Zhi‐Hao , Katz Adriana , Plotnikov Alexander , Karlish Steven J. D. , Jiang Ren‐Wang
Published: April 2019

An efficient one‐pot enzymatic synthesis of cardiac glycosides with varied sugar chain lengths (average yield >80%) was carried out through sequential glycosylation using a steroid glycosyltransferase UGT74AN3 from Catharanthus roseus and a cyclodextrin glycosyltransferase from Bacillus licheniformis. A series of cardiac glycosides were obtained and showed enhanced affinity and selectivity for inhibition of the α2 isoform of Na+/K+‐ATPase. These findings demonstrate the significant potential of the one‐pot biocatalytic approach in the synthesis of diverse cardiac glycosides as potentially safer cardiotonic agents.

magnified image
Synthesis of 3‐Nitroisoxazoles via Copper Acetate‐Mediated Reaction of Benzaldehydes with Nitromethane
Authors: Fu Meiqiang , Li Hui , Su Miaodong , Cao Zhongzhong , Liu Yufeng , Liu Qiang , Guo Cancheng
Published: April 2019

A copper acetate‐mediated reaction of benzaldehydes with nitromethane to synthesis of 3‐nitroisoxazoles is reported. A variety of nitro‐aryl‐disubstituted isoxazole derivatives can be prepared in moderate to good yields with benign functional group tolerance. This protocol is successfully applied in gram‐scale reaction. Preliminary mechanistic studies reveal that the aldehyde provided one carbon atom for the isoxazole ring, and nitromethane provided two carbon atoms and one nitrogen atom for the isoxazole ring. In this protocol, the C−O−N unit in the final isoxazole ring is formed from the rearrangement of nitromethane.

magnified image
Microwave‐Induced Metal Dissolution Synthesis of Core–Shell Copper Nanowires/ZnS for Visible Light Photocatalytic H2 Evolution
Authors: Xiao Shuning , Dai Wenrui , Liu Xiaoyan , Pan Donglai , Zou Hangjun , Li Guisheng , Zhang Guoqiang , Su Chenliang , Zhang Dieqing , Chen Wei , Li Hexing
Published: April 2019

A microwave‐induced metal dissolution strategy is developed for in situ synthesis of copper nanowires/ZnS (CuNWs/ZnS) hybrids with core–shell structure. The CuNWs are used as microwave antennas to create local “super‐hot” surfaces to further initiate ZnS crystallization with full coverage on CuNWs. With the help of S2−, the hot metal surface further results in the CuNWs dissolution with promoted Cu+ diffusion and incorporation into the ZnS lattice. With the narrowed bandgap of ZnS and the strongly coupled interface between CuNWs and ZnS created by microwaves, the as‐prepared hybrid composites exhibit an enhanced activity and stability in visible light for the photocatalytic H2 evolution. The corresponding H2 evolution rate reaches up to 10722 µmol h−1 g−1 with apparent quantum efficiency (AQE) of 69% under 420 nm LED irradiation, showing a remarkably high AQE among the noble‐metal free visible light‐driven photocatalysts and demonstrating a promising potential in practical applications to deal with the energy crisis.
Visible‐Light‐Enabled Synthesis of Pyridyl Benzamides via Oxidative Decarbethoxylation using Copper(I) Iodide/Air at Room Temperature
Authors: Sharma Anup Kumar , Kumar Promod , Vishwakarma Ramesh Kumar , Singh Krishna Nand
Published: April 2019

An efficient synthesis of N‐(pyridin‐2‐yl)benzamides has been developed by the reaction of 2‐aminopyridines and ethyl arylacetates via oxidative decarbethoxylation using visible light/CuI/O2 in acetonitrile at room temperature.
Surface‐Dependent Chemoselectivity in C−C Coupling Reactions
Authors: Chen Zhi , Lin Tao , Zhang Liding , Zhang Lei , Xiang Bingxi , Xu Hu , Klappenberger Florian , Barth Johannes V. , Klyatskaya Svetlana , Ruben Mario
Published: April 2019

Surface‐confined covalent coupling reactions of the linear compound 4‐(but‐3‐en‐1‐ynyl)‐4′‐ethynyl‐1,1′‐biphenyl (1), which contains one alkyne and one enyne group on opposing ends, have been investigated using scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. The reactions show a surface‐dependent chemoselectivity: on Au(111), compound 1 preferentially yields cyclotrimerization products, while on Cu(111), a selective coupling between the enyne and alkyne groups is observed. Linear, V‐shaped string formations combined with Y‐shaped bifurcation motifs result in a random reticulation on the entire surface. DFT calculations show that the C−H⋅⋅⋅πδ− transition state of the reaction between the deprotonated alkyne group and a nearby H‐donor of the alkene group plays a key role in the mechanism and high chemoselectivity. This study highlights a concept that opens new avenues to the surface‐confined synthesis of covalent carbon‐based sp–sp2 polymers.
Carbohydrate Self‐Assembly at Surfaces: STM Imaging of Sucrose Conformation and Ordering on Cu(100)
Authors: Abb Sabine , Tarrat Nathalie , Cortés Juan , Andriyevsky Bohdan , Harnau Ludger , Schön J. Christian , Rauschenbach Stephan , Kern Klaus
Published: April 2019

Saccharides are ubiquitous biomolecules, but little is known about their interaction with, and assembly at, surfaces. By combining preparative mass spectrometry with scanning tunneling microscopy, we have been able to address the conformation and self‐assembly of the disaccharide sucrose on a Cu(100) surface with subunit‐level imaging. By employing a multistage modeling approach in combination with the experimental data, we can rationalize the conformation on the surface as well as the interactions between the sucrose molecules, thereby yielding models of the observed self‐assembled patterns on the surface.
Spatiotemporal Heterogeneity of Reactions in Solution Observed with High‐Speed Single‐Nanorod Rotational Sensing
Authors: Pan Qi , Zhao Hansen , Lin Xijian , He Yan
Published: April 2019

A high‐speed darkfield microscope has been developed to monitor the rapid rotation of single gold nanorods (AuNRs) and used to study the spatiotemporal heterogeneity of chemical reactions in free solution. A wide range of viscosities from 237 cP to 0.8 cP could be detected conveniently. We studied H2O2 decomposition reactions that were catalyzed by AuNRs coated with Pt nanodots (AuNR@PtNDs) and observed two different rotational states. The two states and their transitions are related to the production and the amalgamation of O2 nanobubbles on the nanorod surface depending on H2O2 concentration. In addition, the local fluidic environment of pure water was found to be non‐uniform in time and space. This technique could be applied to study other chemical and biochemical reactions in solution.
One‐Dimensional Cuprous Selenide Nanostructures with Switchable Plasmonic and Super‐ionic Phase Attributes
Authors: Cho Ki‐Hyun , Heo Jaeyoung , Sung Yun‐Mo , Jain Prashant K.
Published: April 2019

Cuprous selenide nanocrystals have hallmark attributes, especially tunable localized surface plasmon resonances (LSPRs) and super‐ionic behavior. These attributes of cuprous selenide are now integrated with a one‐dimensional morphology. Essentially, Cu2Se nanowires (NWs) of micrometer‐scale lengths and about 10 nm diameter are prepared. The NWs exhibit a super‐ionic phase that is stable at temperatures lower than in the bulk, owing to compressive lattice strain along the radial dimension of the NWs. The NWs can be switched between oxidized and reduced forms, which have contrasting phase transition and LSPR characteristics. This work thus makes available switchable, one‐dimensional waveguides and ion‐conducting channels.
The Glycosylation Mechanisms of 6,3‐Uronic Acid Lactones
Authors: Elferink Hidde , Mensink Rens A. , Castelijns Wilke W. A. , Jansen Oscar , Bruekers Jeroen P. J. , Martens Jonathan , Oomens Jos , Rijs Anouk M. , Boltje Thomas J.
Published: April 2019

Uronic acids are important constituents of polysaccharides found on the cell membranes of different organisms. To prepare uronic‐acid‐containing oligosaccharides, uronic acid 6,3‐lactones can be employed as they display a fixed conformation and a unique reactivity and stereoselectivity. Herein, we report a highly β‐selective and efficient mannosyl donor based on C‐4 acetyl mannuronic acid 6,3‐lactone donors. The mechanism of glycosylation is established using a combination of techniques, including infrared ion spectroscopy combined with quantum‐chemical calculations and variable‐temperature nuclear magnetic resonance (VT NMR) spectroscopy. The role of these intermediates in glycosylation is assayed by varying the activation protocol and acceptor nucleophilicity. The observed trends are analogous to the well‐studied 4,6‐benzylidene glycosides and may be used to guide the development of next‐generation stereoselective glycosyl donors.
Reassignments and Corroborations of Oxo‐Bridged Natural Products Directed by OSE and DU8+ NMR Computation
Authors: Kutateladze Andrei G. , Krenske Elizabeth H. , Williams Craig M.
Published: April 2019

Structural misassignments of natural products are prevalent in the literature. Developing methods and theoretical concepts to assist those undertaking structural elucidation is therefore of paramount importance, such that biologists and synthetic chemists avoid pursuing phantom chemical entities. Herein described is a strategy for predicting the isolabilities of oxygen‐substituted bridgehead natural products based on calculations of olefin strain energies, NMR chemical shifts and coupling constants (DU8+). This approach provides corroborating evidence for the structures of certain bridgehead alkene natural products while leading to the reassignment of several other structures.
[Fe(H2O)5(NO)]2+, the “Brown‐Ring” Chromophore
Authors: Monsch Georg , Klüfers Peter
Published: April 2019

Although the “brown‐ring” ion, [Fe(H2O)5(NO)]2+ (1), has been a research target for more than a century, this poorly stable species had never been isolated. We now report on the synthesis of crystals of a salt of 1 which allowed us to tackle the unique bonding situation on an experimental basis. As a result of the bonding analysis, two stretched, spin‐polarised π‐interactions provide the Fe–NO binding—and challenge the concept of “oxidation state”.
Rhodium(I)‐Catalyzed Enantioselective Cyclization of Enynes by Intramolecular Cleavage of the Rh−C Bond by a Tethered Hydroxy Group
Authors: Oonishi Yoshihiro , Masusaki Shuichi , Sakamoto Shunki , Sato Yoshihiro
Published: April 2019

Rhodium(I)‐catalyzed enantioselective intramolecular cyclization of enynes having a hydroxy group in the tether was investigated, and various cyclic compounds possessing a chiral quaternary carbon center were obtained in high yields with high ees. In this cyclization, a Rh−C(sp2) bond in the rhodacyclopentene intermediate, which was formed by enantioselective oxidative cycloaddition of enynes to a chiral rhodium(I) complex, was intramolecularly cleaved by σ‐bond metathesis of a tethered O−H bond in the substrate. Furthermore, it was found that the cyclic compounds were obtained with high ees even when the starting materials having a racemic secondary alcohol moiety were used in this reaction.
Fishers' experiences and perceptions of marine mammals in the South China Sea: Insights for improving community‐based conservation
Authors: Liu Mingming , Lin Mingli , Turvey Samuel T. , Li Songhai
Published: April 2019

The successful conservation of marine mammals is often dependent upon support from local fishing communities, and valuable conservation insights can be obtained through understanding fishers’ attitudes and awareness of marine mammals.

A new local ecological knowledge dataset was obtained through large‐scale questionnaire‐based interviews with 510 artisanal fishers from 16 coastal fishing communities around Hainan, China. Almost all respondents (92.7%) reported regular encounters with marine mammals. Many respondents reported negative interactions with marine mammals, including bycatch (25.5%), consumption (36.1%), and the sale of meat (9.2%), and respondent perceptions of marine mammals were often negative.

Generalized linear models (GLMs) indicated that respondent experiences of marine mammal encounters and bycatch events were mainly predicted by indices of fishing effort and experience, rather than by geographic or socio‐economic factors. Respondent experiences of eating or selling marine mammal meat were predicted by geographic location and by some livelihood and socio‐economic factors. Respondent perceptions of marine mammals were instead predicted by fishing experience and education level.

Classification and regression trees (CARTs) showed that the most important factors determining respondent experiences and perceptions were number of fishing years and educational level, respectively. Both GLMs and CARTs indicated the complex effects of geographic, livelihood, and socio‐economic factors on respondent experiences and perceptions of marine mammals.

Regional community‐based conservation of marine mammals could be promoted through improved regulatory management and environmental education, sustainable ecological exploitation and economic development, and positive partnerships and collaboration between fishing communities, enforcement agencies, and researchers.
On disturbance decoupling problem of Boolean control networks
Authors: Li Yifeng , Zhu Jiandong
Published: April 2019

In this paper, the disturbance decoupling problem for Boolean control networks is investigated in a new viewpoint. A new concept called original disturbance decoupling is proposed and necessary and sufficient conditions for the original disturbance decoupling are given. Similarly, an equivalent condition for thes‐step original disturbance decoupling is obtained. Finally, an algorithm and some simulations for an example are provided to validate the obtained theoretical results.
Enantioseparation of N‐acetyl‐glutamine enantiomers by LC–MS/MS and its application to a plasma protein binding study
Authors: Gao Lei , Xue Yunwen , Zhang Zunjian , Tian Yuan
Published: April 2019

A novel chiral method was developed and validated to determine N‐acetyl‐glutamine (NAG) enantiomers by liquid chromatography–tandem mass spectrometry (LC–MS/MS). Enantioseparation was achieved on a Chiralpak QD‐AX column (150 × 4.6 mm i.d., 5 μm) using methanol–water (50 mm ammonium formate, pH 4.3; 70:30, v/v) at a flow rate of 500 μL/min. The detection was operated with an electrospray ionization source interface in positive mode. The ion transition for NAG enantiomers was m/z 189.0 → 130.0. The retention time of N‐acetyl‐l‐glutamine and N‐acetyl‐d‐glutamine were 15.2 and 17.0 min, respectively. Calibration curves were linear over the range of 0.02–20 μg/mL with r > 0.99. The deviation of accuracy and the coefficient of variation of within‐run and between‐run precision were within 10% for both enantiomers, except for the lower limit of quantification (20 ng/mL), where they deviated <15%. The recovery was >88% and no obvious matrix effect was observed. This method was successfully applied to investigate the plasma protein binding of NAG enantiomers in rats. The results showed that the plasma protein binding of NAG enantiomers was stereoselective. The assay method also exhibited good application prospects for the clinical monitoring of free drugs in plasma.
Biogenic approach to synthesize rod shaped Gd2O3 nanoparticles and its optimization using response surface methodology‐Box–Behnken design model
Authors: Surendra Tammineni Venkata , Mohana Roopan Selvaraj , Khan Maksudur R.
Published: April 2019

The rare earth metal oxide nanoparticles such as gadolinium oxide nanoparticles (Gd2O3 NPs) have been synthesized by green synthesis process using methanolic extract of Moringa oleifera (M oleifera) peel. In this process, the Gd2O3 NPs formation was observed at 280–300 nm in UV–Vis spectroscopy. The XRD pattern of the synthesized Gd2O3 NPs was exactly matched with JCPDS No 3‐065‐3181which confirms the crystalline nature of Gd2O3 NPs. In addition, Energy‐dispersive X‐ray spectroscopy (EDX) analysis was stated that Gd and O elements were present as 70.31 and 29.69%, respectively in Gd2O3 NPs. The SEM and TEM analysis were said Gd2O3 NPs are in rod shape and 26 ± 2 nm in size. Further the synthesized Gd2O3 NPs were confirmed by X‐ray photoemission spectroscopy (XPS). The synthesized Gd2O3 NPs were further examined for anti‐fungal activity against Alternaria saloni (A saloni) and Sclerrotium rolfsii (S rolfsii) and it showed moderate activity. Also, Gd2O3 NPs evaluated as good antibacterial agent against different Gram +ve and Gram −ve bacteria. Moreover, the toxicity of the Gd2O3 NPs on red blood cells (RBCs) of the human blood was determined using hemolytic assay, the obtained results were stated the synthesized Gd2O3 NPs are nontoxic to the human erythrocytes. The photocatalytic activity against malachite green (MG) dye was tested and confirmed as 92% of dye was degraded within 2 hr by Gd2O3 NPs. The results were stated the green synthesized Gd2O3 NPs are good anti‐fungal agents, nontoxic and we can use as a photocatalyst. Copyright © 2019 John Wiley & Sons, Ltd.
Biochemical and Structural Characterization of XoxG and XoxJ and Their Roles in Lanthanide‐Dependent Methanol Dehydrogenase Activity
Authors: Featherston Emily R. , Rose Hannah R. , McBride Molly J. , Taylor Ellison M. , Boal Amie K. , Cotruvo Joseph A.
Published: April 2019

Lanthanide (Ln)‐dependent methanol dehydrogenases (MDHs) have recently been shown to be widespread in methylotrophic bacteria. Along with the core MDH protein, XoxF, these systems contain two other proteins, XoxG (a c‐type cytochrome) and XoxJ (a periplasmic binding protein of unknown function), about which little is known. In this work, we have biochemically and structurally characterized these proteins from the methyltroph Methylobacterium extorquens AM1. In contrast to results obtained in an artificial assay system, assays of XoxFs metallated with LaIII, CeIII, and NdIII using their physiological electron acceptor, XoxG, display Ln‐independent activities, but the Km for XoxG markedly increases from La to Nd. This result suggests that XoxG′s redox properties are tuned specifically for lighter Lns in XoxF, an interpretation supported by the unusually low reduction potential of XoxG (+172 mV). The X‐ray crystal structure of XoxG provides a structural basis for this reduction potential and insight into the XoxG–XoxF interaction. Finally, the X‐ray crystal structure of XoxJ reveals a large hydrophobic cleft and suggests a role in the activation of XoxF. These studies enrich our understanding of the underlying chemical principles that enable the activity of XoxF with multiple lanthanides in vitro and in vivo.
Recent Advances in Solvent‐Free Asymmetric Catalysis
Authors: Tavakolian Mina , Vahdati‐Khajeh Saleh , Asgari Sepideh
Published: April 2019

It is well‐known that solvent is one of the most important factors that affect chemical reactions. This factor is more noticeable and impressive in the asymmetric reactions where the effective interaction of reactants and the creation of a uniform chiral environment is necessary. Nevertheless, when reactions are carried out in the absence of solvent, some privileged advantages such as easy work up, short reaction time, lack of waste solvents, and following the green chemistry principles, are appeared. Therefore, according to the importance of asymmetric synthesis and green chemistry, solvent‐free asymmetric catalysis can act as a considerable and necessary subject in synthetic chemistry. In this review, we have a survey on the solvent‐free asymmetric synthesis by the use of either homogeneous or heterogeneous chiral catalysts.
A New Route to Cyclohexanone using H2CO3 as a Molecular Catalytic Ligand to Boost the Thorough Hydrogenation of Nitroarenes over Pd Nanocatalysts
Authors: Zhao Tian‐Jian , Zhang Jun‐Jun , Zhang Bing , Liu Yong‐Xing , Lin Yun‐Xiao , Wang Hong‐Hui , Su Hui , Li Xin‐Hao , Chen Jie‐Sheng
Published: April 2019

Carbon dioxide has been important in green chemistry, especially in catalytic and chemical engineering applications. While exploring CO2 to produce cyclohexanone for nylon or nylon 66 that is currently produced with low yields using harsh catalytic methods, we made the exciting discovery that carbonic acid, generated from dissolved CO2 in water, was utilized as molecular catalytic ligand to produce cyclohexanone via the hydrogenation of nitrobenzene in aqueous solution that uses Pd catalysts with a total yield higher than 90 %. Importantly, the gaseous nature of catalytic ligand H2CO3 profoundly simplifies post‐catalysis cleanup unlike liquid or solid catalysts. This new green catalysis strategy demonstrated the universality for hydrogenation of aromatic compounds like aniline and N‐methylaniline and could be broadly applicable in other catalytic field like artificial photosynthesis and electrocatalytic organic synthesis.
How Do Structurally Distinct Au/α‐Fe2O3 Interfaces Determine Surface OH/H2O reactivity, Intermediate Evolution, and Product Formation in Low‐temperature Water‐gas Shift Reaction?
Authors: Gu Lingli , Zeng Yiqiang , Feng Yina , Jiang Wu , Ji Weijie , Arandiyan Hamidreza , Au Chak‐Tong
Published: April 2019

Three structurally distinct interfaces, i. e. Au/α‐Fe2O3‐THB‐Air, Au/α‐Fe2O3‐HS‐Air, and Au/α‐Fe2O3‐QC‐Air, with the major substrate facet being {113}, {001}, and {012} respectively, were controllably prepared. The low temperature water gas shift (WGS) reaction (100–260 °C) was applied to these unique systems to reveal how these structurally distinct interfaces can impact on the reaction behavior. With the detailed performance evaluation plus the characterizations of CO‐TPSR, XPS, and in situ‐FTIR in particular, the correlations between the evolution of different intermediates and the distinct catalytic behaviors have been established. The substrate facet structure and the Au entity largely determine the form and reactivity of surface OH/H2O species which in turn determine the formation of different intermediates and eventually the product formation. The Au/α‐Fe2O3‐THB‐Air is enriched with oxygen vacant sites, favorable for dissociative adsorption of H2O, carboxyl intermediate formation and H2 production. The Au/α‐Fe2O3‐HS‐Air is enriched with surface lattice oxygen, favorable for molecular adsorption of H2O, formate intermediate formation, and CO2 production. The Au/α‐Fe2O3‐QC‐Air interface is enriched with surface Fe sites, favorable for dissociative adsorption of H2O and evolution of stable carboxyl intermediate as well as isolated OH species at low reaction temperatures. The findings are informative to control the interfacial structure for the WGS and other reactions.
Construction of a Stable Crystalline Polyimide Porous Organic Framework for C2H2/C2H4 and CO2/N2 Separation
Authors: Jiang Lingchang , Wang Pengyuan , Li Meiping , Zhang Panpan , Li Jialu , Liu Jia , Ma Yanhang , Ren Hao , Zhu Guangshan
Published: April 2019

Utilization of porous materials for gas capture and separation is a hot research topic. Removal of acetylene (C2H2) from ethylene (C2H4) is important in the oil refining and petrochemical industries, since C2H2 impurities deactivate the catalysts and terminate the polymerization of C2H4. Carbon dioxide (CO2) emission from power plants contributes to global climate change and threatens the survival of life on this planet. Herein, 2D crystalline polyimide porous organic framework PAF‐120, which was constructed by imidization of linear naphthalene‐1,4,5,8‐tetracarboxylic dianhydride and triangular 1,3,5‐tris(4‐aminophenyl)benzene, showed significant thermal and chemical stability. Low‐pressure gas adsorption isotherms revealed that PAF‐120 exhibits good selective adsorption of C2H2 over C2H4 and CO2 over N2. At 298 K and 1 bar, its C2H2 and CO2 selectivities were predicted to be 4.1 and 68.7, respectively. More importantly, PAF‐120 exhibits the highest selectivity for C2H2/C2H4 separation among porous organic frameworks. Thus PAF‐120 could be a suitable candidate for selective separation of C2H2 over C2H4 and CO2 over N2.