bluuebunny/crossref_metadata_2025 huggingface dataset:
The Arab Oral Epic of the Bani Hilal Tribe: Al‐Sirah al‐Hilaliyyah
Authors: Slyomovics Susan
Published: October 2019

The heroic deeds of the Bani Hilal (Banī Hilāl) tribe of Bedouin Arabs, as they migrate during the tenth and eleventh centuries from the Arabian Peninsula across the Levant, Egypt, and into North Africa, are preserved throughout the Arabic‐ and Amazigh/Berber‐speaking world in a cycle of narratives known asal‐Sirah al‐Hilaliyyah(al‐Sīrah al‐Hilāliyyah). Among several extant Arab epics in written versions from a vast, understudied corpus of manuscripts and cheap folk print editions, only this “Epic of the Bani Hilal Tribe” endures as a living tradition of oral performance by poets and reciters in parts of the Maghreb and Arab East. To this day, performances by epic poets as well as cheap printed books circulate in poetry and prose, written and oral forms. The Hilali epic may be chanted, sung, and spoken with or without the customary accompanyingrabāb(spike‐fiddle) andṭār(frame drum).
Between Realism and Modernism: Chinua Achebe and the Making of African Literature
Authors: Gikandi Simon
Published: October 2019

This chapter discusses Chinua Achebe's seminal role in the foundation of modern African literature and his contribution to the culture of world letters in the second half of the twentieth century. Achebe started writing in the last years of British colonial rule in West Africa and in, his fictions, he sought to both understand the tragedy of colonial modernity, recuperate narratives of African life outside the colonialist idiom, and imagine a decolonized future. Using the English language against itself, Achebe adopted creative writing as a strategy of giving Africans a voice in the post‐World War II order. And coming to writing at the end of modernism, Achebe would combine high modernist style with older forms of realism to create an idiom for understanding postcolonial societies, their failures and promises.
Improved dosimetric accuracy with semi‐automatic contour propagation of organs‐at‐risk in glioblastoma patients undergoing chemoradiation
Authors: Lee Sangjune , Stewart James , Lee Young , Myrehaug Sten , Sahgal Arjun , Ruschin Mark , Tseng Chia‐Lin
Published: October 2019

Background

We study the changes in organs‐at‐risk (OARs) morphology as contoured on serial MRIs during chemoradiation therapy (CRT) of glioblastoma (GBM). The dosimetric implication of assuming non‐deformable OAR changes and the accuracy and feasibility of semi‐automatic OAR contour propagation are investigated.

Methods

Fourteen GBM patients who were treated with adjuvant CRT for GBM prospectively underwent MRIs on fractions 0 (i.e., planning), 10, 20, and 1 month post last fraction of CRT. Three sets of OAR contours — (a) manual, (b) rigidly registered (static), and (c) semi‐automatically propagated — were compared using Dice similarity coefficient (DSC) and Hausdorff distance (HD). Dosimetric impact was determined by comparing the minimum dose to the 0.03 cc receiving the highest dose (D0.03 cc) on a clinically approved reference, non‐adapted radiation therapy plan.

Results

The DSC between the manual contours and the static contours decreased significantly over time (fraction 10: [mean ± 1 SD] 0.78 ± 0.17, post 1 month: 0.76 ± 0.17, P = 0.02) while the HD (P = 0.74) and the difference in D0.03cc did not change significantly (P = 0.51). Using the manual contours as reference, compared to static contours, propagated contours have a significantly higher DSC (propagated: [mean ± 1 SD] 0.81 ± 0.15, static: 0.77 ± 0.17, P < 0.001), lower HD (propagated: 3.77 ± 1.8 mm, static: 3.96 ± 1.6 mm, P = 0.002), and a significantly lower absolute difference in D0.03cc (propagated: 101 ± 159 cGy, static: 136 ± 243 cGy, P = 0.019).

Conclusions

Nonrigid changes in OARs over time lead to different maximum doses than planned. By using semi‐automatic OAR contour propagation, OARs are more accurately delineated on subsequent fractions, with corresponding improved accuracy of the reported dose to the OARs.
The Influence of Initial Defects on Impact Ignition of Aluminum/Polytetrafluoroethylene Reactive Material
Authors: Ren Huilan , Li Wei , Ning Jianguo , Liu Yuanbin
Published: October 2019

Aluminum/polytetrafluoroethylene (Al/PTFE) reactive material is a typical multifunctional energetic material, which can release enormous energy under impact loading. To clarify its ignition mechanism, a Split Hopkinson pressure bar (SHPB) is used to conduct the impact ignition experiment on reactive materials with different initial defects. The experimental results show that the measured minimum specific incident energy that can cause the ignition for the specimen without pre‐impact (MSed specimen) increases slowly from 97.5 to 101 Jcm−2 with the molding pressure first, but drops substantially to 83.3 Jcm−2 as the molding pressure increases to 100 MPa. In addition, only the MSed specimens with the molding pressure above 100 MPa are ignited at the third stress pulse. Combined with the results of scanning electron microscopy, it is found that the existence of local larger pores inside the MSed specimens with high molding pressures (100, 120, and 150 MPa) contributes to the increase in damage level under impact and thus reduces the ignition threshold. The impact ignition experiment on the pre‐impacted specimens (MSed + PIed specimens) indicates that a phenomenon of damage sensitization exists in Al/PTFE reactive materials, confirming that the initial defects and damage evolution have significant effects on the impact ignition of the material.
Tailoring Vanadium Dioxide Film Orientation Using Nanosheets: a Combined Microscopy, Diffraction, Transport, and Soft X‐Ray in Transmission Study
Authors: Le Phu Tran Phong , Hofhuis Kevin , Rana Abhimanyu , Huijben Mark , Hilgenkamp Hans , Rijnders Guus A.J.H.M. , ten Elshof Johan E. , Koster Gertjan , Gauquelin Nicolas , Lumbeeck Gunnar , Schüßler‐Langeheine Christian , Popescu Horia , Fortuna Franck , Smit Steef , Verbeek Xanthe H. , Araizi‐Kanoutas Georgios , Mishra Shrawan , Vaskivskyi Igor , Dürr Hermann A. , Golden Mark S.
Published: October 2019

Vanadium dioxide (VO2) is a much‐discussed material for oxide electronics and neuromorphic computing applications. Here, heteroepitaxy of VO2 is realized on top of oxide nanosheets that cover either the amorphous silicon dioxide surfaces of Si substrates or X‐ray transparent silicon nitride membranes. The out‐of‐plane orientation of the VO2 thin films is controlled at will between (011)M1/(110)R and (−402)M1/(002)R by coating the bulk substrates with Ti0.87O2 and NbWO6 nanosheets, respectively, prior to VO2 growth. Temperature‐dependent X‐ray diffraction and automated crystal orientation mapping in microprobe transmission electron microscope mode (ACOM‐TEM) characterize the high phase purity, the crystallographic and orientational properties of the VO2 films. Transport measurements and soft X‐ray absorption in transmission are used to probe the VO2 metal–insulator transition, showing results of a quality equal to those from epitaxial films on bulk single‐crystal substrates. Successful local manipulation of two different VO2 orientations on a single substrate is demonstrated using VO2 grown on lithographically patterned lines of Ti0.87O2 and NbWO6 nanosheets investigated by electron backscatter diffraction. Finally, the excellent suitability of these nanosheet‐templated VO2 films for advanced lensless imaging of the metal–insulator transition using coherent soft X‐rays is discussed.
Interaction of Human Mesenchymal Stem Cells with Soft Nanocomposite Hydrogels Based on Polyethylene Glycol and Dendritic Polyglycerol
Authors: Randriantsilefisoa Rotsiniaina , Hou Yong , Pan Yuanwei , Camacho José Luis Cuellar , Kulka Michaël W. , Zhang Jianguang , Haag Rainer
Published: October 2019

Keeping the stemness of human mesenchymal stem cells (hMSCs) and their adipocyte differentiation potential is critical for clinical use. However, these features are lost on traditional substrates. hMSCs have often been studied on stiff materials whereas culturing hMSCs in their native niche increases their potential. Herein, a patterned hydrogel nanocomposite with the stiffness of liver tissues is obtained without any molding process. To investigate hMSCs' mechanoresponse to the material, the RGD spacing units and the stiffness of the hydrogels are dually tuned via the linker length. This work suggests that hMSCs' locomotion is influenced by the nature of the hydrogel layer (bulk or thin film). Contrary to on bulk surfaces, cell traction occurs during cell spreading on thin films. In addition, hMSCs' spreading behavior varies from shorter to longer linker‐based hydrogels, where on both surfaces hMSCs maintains their stemness as well as their adipogenic differentiation potential with a higher number of adipocytes for nanocomposites with a longer polymer linker. Overall, this work addresses the need for a new alternative for hMSCs culture allowing the cells to differentiate exclusively into adipocytes. This material represents a cell‐responsive platform with a tissue‐mimicking architecture given by the mechanical and morphological properties of the hydrogel.
The Biomolecular Corona in 2D and Reverse: Patterning Metal–Phenolic Networks on Proteins, Lipids, Nucleic Acids, Polysaccharides, and Fingerprints
Authors: Yun Gyeongwon , Richardson Joseph J. , Capelli Marco , Hu Yingjie , Besford Quinn A. , Weiss Alessia C. G. , Lee Hojae , Choi Insung S. , Gibson Brant C. , Reineck Philipp , Caruso Frank
Published: October 2019

The adsorption of biomolecules onto nanomaterials can alter the performance of the nanomaterials in vitro and in vivo. Recent studies have primarily focused on the protein “corona”, formed upon adsorption of proteins onto nanoparticles in biological fluids, which can change the biological fate of the nanoparticles. Conversely, interactions between nanomaterials and other classes of biomolecules namely, lipids, nucleic acids, and polysaccharides have received less attention despite their important roles in biology. A possible reason is the challenge associated with investigating biomolecule interactions with nanomaterials using current technologies. Herein, a protocol is developed for studying bio–nano interactions by depositing four classes of biomolecules (proteins, lipids, nucleic acids, and polysaccharides) and complex biological media (blood) onto planar substrates, followed by exposure to metal–phenolic network (MPN) complexes. The MPNs preferentially interact with the biomolecule over the inorganic substrate (glass), highlighting that patterned biomolecules can be used to engineer patterned MPNs. Subsequent formation of silver nanoparticles on the MPN films maintains the patterns and endows the films with unique reflectance and fluorescence properties, enabling visualization of latent fingerprints (i.e., invisible residual biomolecule patterns). This study demonstrates the potential complexity of the biomolecule corona as all classes of biomolecules can adsorb onto MPN‐based nanomaterials.
Synthese quartärer Kohlenstoffzentren durch palladiumkatalysierte Dicarbofunktionalisierung
Authors: Koy Maximilian , Bellotti Peter , Katzenburg Felix , Daniliuc Constantin G. , Glorius Frank
Published: October 2019

Die redoxneutrale Dicarbofunktionalisierung tri‐ und tetrasubstituierter Olefine zur Bildung verschiedener (hetero‐)cyclischer Verbindungen unter photoinduzierter Palladiumkatalyse wird beschrieben. Diese Kaskadenreaktion wurde verwendet, um zahlreiche an Aryl‐ oder Alkylbromide gebundene hochdekorierte Olefine mit Styrolen oder Acrylamiden zu kuppeln (>50 Beispiele). Durch dieses Protokoll können ein oder zwei zusammenhängende quartäre Kohlenstoffzentren in einem einzigen Schritt gebildet werden. Die Produkte ließen sich leicht diversifizieren und zur Synthese eines Analogons von bioaktiven Oxindolen verwenden.
The Thermal Rearrangement of an NHC‐Ligated 3‐Benzoborepin to an NHC‐Boranorcaradiene
Authors: Shimoi Masaki , Kevlishvili Ilia , Watanabe Takashi , Maeda Katsuhiro , Geib Steven J. , Curran Dennis P. , Liu Peng , Taniguchi Tsuyoshi
Published: October 2019

An N‐heterocyclic‐carbene‐ligated 3‐benzoborepin with a bridged structure has been synthesized by double radical trans‐hydroboration of benzo[3,4]cycloundec‐3‐ene‐1,5‐diyne with an N‐heterocyclic carbene borane. The thermal reaction of the NHC‐ligated borepin at 150 °C gives an isolable NHC‐boranorcaradiene. Experiments and density functional theory calculations support a mechanism whereby the borepin initially rearranges to a boranorcaradiene by a thermal 6π‐electrocyclic reaction. This is followed by 1,5‐boron shift to give a rearranged boranorcaradiene. This shift occurs with stereoinversion at boron through a transition state with open‐shell diradical character. This is the first example of the isolation of a boranorcaradiene from a thermal reaction of a borepin.
Parallele homochirale und antiparallele heterochirale Wasserstoffbrücken‐Interaktionsflächen in multihelikalen abiotischen Foldameren
Authors: Mazzier Daniela , De Soumen , Wicher Barbara , Maurizot Victor , Huc Ivan
Published: October 2019

Eine Wasserstoffbrücken‐Interaktionsfläche zwischen helikalen aromatischen Oligoamidfoldameren wurde gezielt entworfen, um die Bildung eines Helix‐Turn‐Helix‐Motivs mit einer Kopf‐zu‐Schwanz‐Anordnung zweier Helices unterschiedlicher Händigkeit zu ermöglichen. Dieses Design ist komplementär zu einem früheren Helix‐Turn‐Helix‐Motiv mit einer Kopf‐zu‐Kopf‐Anordnung zweier Helices identischer Händigkeit. Beide Motive zeigen eine vergleichbare Stabilität und führen, wenn sie miteinander kombiniert werden, zu einer unimolekularen Tetra‐Helix‐Anordnung, welche die bisher größte abiotische tertiäre Struktur darstellt.
Synthesis of All‐Carbon Quaternary Centers by Palladium‐Catalyzed Olefin Dicarbofunctionalization
Authors: Koy Maximilian , Bellotti Peter , Katzenburg Felix , Daniliuc Constantin G. , Glorius Frank
Published: October 2019

The redox‐neutral dicarbofunctionalization of tri‐ and tetrasubstituted olefins to form a variety of (hetero)cyclic compounds under photoinduced palladium catalysis is described. This cascade reaction process was used to couple styrenes or acryl amides with a broad range of highly decorated olefins tethered to aryl or alkyl bromides (>50 examples). This procedure enables one or two contiguous all‐carbon quaternary centers to be formed in a single step. The products could be readily diversified and applied in the synthesis of a bioactive oxindole analogue.
Mediating Reaction Orthogonality in Polymer and Materials Science
Authors: Corrigan Nathaniel , Ciftci Mustafa , Jung Kenward , Boyer Cyrille
Published: October 2019

Selective control of chemical reactions is critical for the proper regulation of processes ranging from intricate biological systems to large scale industrial manufacturing. The progression of synthetic chemistry toward the complexity seen in Nature requires increased control over many concurrent chemical reactions in a non‐interfering (orthogonal) fashion. Fortunately, the practically endless pool of synthetic chemical reactions developed to date can often be combined in an orthogonal manner to provide elegant solutions to complex chemical problems. In this review, we first highlight some of the many photochemical reactions that have been applied in orthogonal reaction protocols; the highly selective nature of photochemical reactions makes them well‐suited for independent activation in the presence of other reaction components. The application of these orthogonal reactions, especially photochemical reactions, for the synthesis and modification of polymers and polymeric materials is also summarized. Importantly, the use of orthogonal chemical reactions can provide additional opportunities for synthesizing advanced and functional polymeric materials compared to traditional synthetic procedures.
Surface‐Polarity‐Induced Spatial Charge Separation Boosts Photocatalytic Overall Water Splitting on GaN Nanorod Arrays
Authors: Li Zheng , Zhang Liang , Liu Yong , Shao Chenyi , Gao Yuying , Fan Fengtao , Wang Junxi , Li Jinmin , Yan Janchang , Li Rengui , Li Can
Published: October 2019

Photocatalytic overall water splitting has been recognized as a promising approach to convert solar energy into hydrogen. However, most of the photocatalysts suffer from low efficiencies mainly because of poor charge separation. Herein, taking a model semiconductor gallium nitride (GaN) as an example, we uncovered that photogenerated electrons and holes can be spatially separated to the nonpolar and polar surfaces of GaN nanorod arrays, which is presumably ascribed to the different surface band bending induced by the surface polarity. The photogenerated charge separation efficiency of GaN can be enhanced significantly from about 8 % to more than 80 % via co‐exposing polar and nonpolar surfaces. Furthermore, spatially assembling reduction and oxidation cocatalysts on the nonpolar and polar surfaces remarkably boosts photocatalytic overall water splitting, with the quantum efficiency increased from 0.9 % for the film photocatalyst to 6.9 % for the nanorod arrays photocatalyst.
A novel drug loading and release from a thermoresponsive hydrogel formedin situemulsion polymerization
Authors: Zhao Xiaoyan , Debeli Dereje Kebebew , Shan Guorong
Published: October 2019

A facile thermoresponsive injectable hydrogel is prepared from stearyl methacrylate (SMA) andN‐isopropyl acrylamide (NIPAM) copolymers via reversible addition‐fragmentation chain‐transfer (RAFT) emulsion polymerization method. By regulating the content of the oil phase, emulsions with divergent properties are obtained. The yield stress and the viscosity results of the emulsions increase evidently as the initial content of the oil phase increase from 10 to 40%. The microstructures of 10% oil content sample (SN10) is seen as a dispersed particle whereas 20, 30, and 40% oil content samples (SN20, SN30, and SN40) appear as aggregated particles in a dilute solution that shows the microscopical phase transitions of the emulsions. Increasing the temperature from 15 to 45 °C, phase separation takes place, the emulsions contract to squeeze the water. A sharp decrease in particle size is noticed when the temperature increase from 30 to 35 °C. In this point, hydrophilic drug procaine is loaded and release experiments are conducted using thermoresponsive injectable hydrogel. The drug loading and release results are evaluated using the Weibull distribution model and the Fick's law of diffusion that precisely works out. A thermoresponsive injectable hydrogel offers an efficient, cost‐effective, and scalable approach towards controlled release of drugs. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2019,137, 48669.
Experimentelle und numerische Untersuchung einer bestehenden Eisenbahnbrücke bei Zugüberfahrt
Authors: Reiterer Michael
Published: October 2019

Die dynamischen Kennwerte und das Schwingungsantwortverhalten bei Zugüberfahrt werden an einem schiefwinkeligen einfeldrigen Stahlbetonplattentragwerk experimentell und numerisch untersucht. Bei der numerischen Untersuchung werden unterschiedliche Detaillierungsgrade der Brückenmodelle betrachtet und die Ergebnisse der berechneten Eigenfrequenzen und Schwingungsantworten bei Zugüberfahrt miteinander verglichen und diskutiert. Die experimentellen Untersuchungen beinhalten die Anwendung der krafterregten Schwingungsanregungsmethode zur Ermittlung der tatsächlichen Größe der dynamischen Kennwerte des Tragwerks und die Messung der Tragwerksreaktionen bei Zugüberfahrt. Mit den experimentell ermittelten dynamischen Kennwerten werden die numerischen Brückenmodelle kalibriert und eine Neuberechnung der Schwingungsantworten wird durchgeführt. Die Abweichungen der bei Zugüberfahrt am realitätsangepassten numerischen Modell ermittelten Tragwerksreaktionen werden mit den messtechnisch ermittelten Werten verglichen. Ziel des Vergleichs ist die Ermittlung und Darlegung von anzuwendenden Signalanalyse‐ bzw. Filtermethoden zur Erzielung einer bestmöglichen Übereinstimmung der Tragwerksreaktionen des Modells mit der Realität. Es werden Empfehlungen für die Wahl des Detaillierungsgrads der numerischen Brückenmodelle bei Zugüberfahrtssimulationen und für die Festlegung der maßgebenden Eigenfrequenzen bei der Durchführung von Schwingungsmessungen an realen Tragwerken gegeben.
Die BBQ‐Richtlinie des DAfStb
Authors: Fingerloos Frank , Meyer Lars , Breitenbücher Rolf
Published: October 2019

Die Normen des Betonbaus bilden derzeit die unterschiedliche Komplexität der Bauaufgaben nur in Ansätzen ab. Die Struktur des Regelwerks erschwert zudem die Interaktion bzw. die Kommunikation. Die Betonbaunormen werden jedoch insgesamt nur dann zukunftsfähig sein, wenn sie für die verschiedenen Ansprüche, Erwartungen und Randbedingungen in Planung und Bauausführung und Baustoffherstellung in gleicher Weise passende und insofern differenzierte Lösungsansätze vorsehen und besser aufeinander abgestimmt sind.

Um eine solche bessere Abstimmung zwischen Planung, Baustoff und Bauausführung zu unterstützen, hat der Deutsche Ausschuss für Stahlbeton beschlossen, das Konzept der BetonBauQualitätsklassen (BBQ‐Klassen) zu etablieren, mit dem qualitätssichernde Maßnahmen in unterschiedlicher Intensität abhängig von der Komplexität der Bauaufgaben im Betonbau organisiert werden sollen. Dieser Bericht fasst den aktuellen Sachstand zur Entwicklung des BBQ‐Konzepts und der Bearbeitung der DAfStb‐BBQ‐Richtlinie zusammen.
Tuning optical properties and optical rotation of 3‐mercaptopropionic acid capped organic–inorganic hybrid perovskites
Authors: Qu Junfeng , Jiang Han , Xu Shuhong , Wang Chunlei , Ban Dayan
Published: October 2019

The emission wavelength of organic–inorganic hybrid perovskite quantum dots (QDs) can be tuned by controlling reaction time relevant to the halide exchange. It is because halide exchange with different time would lead to different molar ratio of halides in perovskite QDs such as Cl and Br. Here, to research the ligand's effect on the halide exchange, this work synthesized 3‐mercaptopropionic acid (MPA)‐capped CH3NH3PbBrxCl3‐x QDs. It was found that SH− of MPA appeared to inhibit the halide exchange during the reation. Moreover, although the MPA‐capped CH3NH3PbBrxCl3‐x QDs did not contain the chiral centre, they exhibit the optical rotation. This may provide a method for chirality manipulation of perovskite.
Understanding variation in the relationship between environmental management practices and firm performance across studies: A meta‐analytic review
Authors: Tsai Kuen‐Hung , Huang Chi‐Tsun , Chen Zi‐Hyo
Published: October 2019

The relationship between environmental management practices and firm performance has continuously received much attention in academic research. As existing literature on the link of the two constructs is characterized by heterogeneous research characteristics and mixed empirical evidence, one interesting question arises: Do research characteristics affect the magnitude and direction of the relationship between environmental management practices and firm performance? Amassing a database of 92 studies, 199 effect sizes, and 72,258 firms, we examine this question by conducting a meta‐analysis. The characteristics investigated in this study include item number of performance measures, year of data collection, industry type, economic development, and Hofstede's five cultural dimensions. A meta‐regression reveals that environmental management practices are positively associated with firm performance and that the degree of this association depends on these contexts. Specifically, the environmental management practices–performance relationship increases with year of data collection, is stronger with multiple item measures, and is higher for firms in developed countries and in cultures characterized by high power distance, low individualism, low uncertainty avoidance, and low long‐term orientation.
Design of Ceria Catalysts for Low‐Temperature CO Oxidation
Authors: Kim Hyung Jun , Jang Myeong Gon , Shin Dongjae , Han Jeong Woo
Published: October 2019

A catalyst active to carbon monoxide (CO) oxidation at low temperature is essential for environmental conservation, saving fuel and improvement of the quality of human life. Rational design of CO oxidation catalyst on the basis of comprehensive understanding of physicochemical properties of catalytic materials, rather than simply searching for the catalyst based on trial‐and‐error, is a promising approach to meet the increasingly stringent regulations. This review covers metal‐doped and ‐loaded system based on CeO2 catalysts as strategies to significantly improve CO oxidation activity at low temperature. When incorporated into CeO2 lattice, active metals significantly lower the oxygen vacancy formation energy (Evf) of the catalyst surface, resulting in high catalytic activities at low temperature. When the active metals are loaded on the CeO2 surface, many active sites could be acquired by increasing the dispersion, and the catalytic activity can be dramatically improved by newly introducing the interfacial sites between the metals and the CeO2 support. Doping the support could further improve this loaded system in terms of specific surface area, oxygen vacancy formation, and spillover effects. In this review, based on this knowledge, we propose a rational design approach to a robust low‐temperature CO oxidation catalysts. The desirable CO oxidation catalysts identified from the interplay between theoretical and experimental approaches would ultimately improve the quality of human life, and create potential economic benefits by alleviating air pollution.
Light Hydrocarbon Separations Using Porous Organic Framework Materials
Authors: Zhang Shuhao , Taylor Mercedes K. , Jiang Lingchang , Ren Hao , Zhu Guangshan
Published: October 2019

Light hydrocarbons (C1–C3) are used as basic energy feedstocks and as commodity organic compounds for the production of many industrially necessary chemicals. Due to the nature of the raw materials and production processes, light hydrocarbons are generated as mixtures, but the high‐purity single‐component products are of vital importance to the petrochemical industry. Consequently, the separation of these C1–C3 products is a crucial industrial procedure that comprises a significant share of the total global energy consumption per year. As a complement to traditional separation methods (distillation, partial hydrogenation, etc.), adsorptive separations using porous solids have received widespread attention due to their lower energy costs and higher efficiency. Extensive research has been devoted to the use of porous materials such as zeolites and metal‐organic frameworks (MOFs) as solid adsorbents for these key separations, owing to the high porosity, tunable pore structures, and unsaturated metal sites present in these materials. Recently, porous organic framework (POF) materials composed of organic building blocks linked by covalent bonds have also shown excellent properties in light hydrocarbon adsorption and separation, sparking interest in the use of these materials as adsorbents in separation processes. This Minireview summarizes the recent advances in the use of POFs for light hydrocarbon separations, including the separation of mixtures of methane/ethane, methane/propane, ethylene/ethane, acetylene/ethylene, and propylene/propane, while highlighting the relationships between the structural features of these materials and their separation performances. Finally, the difficulties, challenges, and opportunities associated with leveraging POFs for light hydrocarbon separations are discussed to conclude the review.
Stoichiometry‐Controlled Synthesis of Nanoparticulate Mixed‐Metal Oxyhydroxide Oxygen Evolving Catalysts by Electrochemistry in Aqueous Nanodroplets
Authors: Jeun Young Eun , Park Joon Ho , Kim Joo Yeon , Ahn Hyun S.
Published: October 2019

Mixed‐metal oxyhydroxides—especially those of Ni and Fe—are one of the most active classes of materials known for catalyzing the oxygen evolution reaction (OER). Here, nanoparticulate mixed metal oxyhydroxides (of Ni, Fe, and Co) were prepared on an electrode surface by electrochemical reaction of a precursor solution encapsulated in aqueous nanodroplets (AnDs), with each of the droplets containing 10 s of attoliters of fluid. Electrode reactions and synthesis can be monitored in situ by electrochemistry as single AnD stochastically lands and interacts with the working electrode. Resultant metal oxyhydroxide nanoparticles can be size and composition controlled precisely by modulating the precursor solution stored in the AnD. Nanoparticulate metal oxyhydroxides were implemented as catalysts for the OER and exhibited superior catalysis compared to their thin‐film counterparts, demonstrating a hundred‐thousand‐fold enhancement in atom efficiency at comparable turnover rates.
Improving classification and clustering techniques using GPUs
Authors: Jararweh Yaser , Shehab Mohammed A. , Yaseen Qussai , Al‐Ayyoub Mahmoud
Published: October 2019

Classification and clustering techniques are used in different applications. Large‐scale big data applications such as social networks analysis applications need to process large data chunks in a short time. Classification and clustering tasks in such applications consume a lot of processing time. Improving the performance of classification and clustering algorithms enhances the performance of applications that use such type of algorithms. This paper introduces an approach for exploiting the graphics processing unit (GPU) platform to improve the performance of classification and clustering algorithms. The proposed approach uses two GPUs implementations, which are the pure GPU or GPU‐only implementation and the GPU‐CPU hybrid implementation. The results show that the hybrid implementation, which optimizes the subtask scheduling for both the CPU and the GPU processing elements, outperforms the approach that uses only the GPU.
In Situ Detection of Nucleation in High‐Temperature Solutions
Authors: Schneider Andreas G. F. , Sass Paul , Schöndube Robert , Jesche Anton
Published: October 2019

The state of a sample during crystal growth from high‐temperature solutions is not accessible in conventional furnace systems. An optimization of the growth parameters often requires arduous trial and error procedures, in particular, in the case of novel multicomponent systems with unknown phase diagrams. Here a measurement technique based on lock‐in amplification is presented that allows for in situ detection of the liquidus and solidus temperatures as well as structural phase transitions. A thin, metallic measurement wire is mounted in close vicinity to the melt. Characteristic anomalies in the time‐dependent electrical resistivity of this wire allow for the detection of latent heat release without using a reference crucible. The method is implemented in a “feedback furnace” and enables an adjustment of the temperature profile based on the occurrence or absence of phase transitions. The absolute temperature serves as an additional source of information. Obtained phase transition temperatures are in good agreement with differential thermal analysis.
Empirical study of dynamics of amoebiasis transmission in mobile ad hoc networks (MANETs)
Authors: Mishra Ankush , Saha Snehanshu , Makhija Simran , Sinha Sumana , Raychoudhury Vaskar , CC Sobin
Published: October 2019

We present a study of the novel mathematical model, CISER, in this work. The proposed model is a more general variant of the SIR epidemic model for representing information spread. The work provides an analysis of the mathematical model, in particular, the inclusion of carrier and exposed states in providing a more generalized representation toward SIR. The model also provides an accurate description of the disease amoebiasis and relates the disease characteristics to message propagation. We derive various properties of importance and depict the model representation of various states of spread (message propagation) through numerical results. Based on this model, we then provide an epidemic controlled flooding mechanism for information spread in a mobile ad hoc network (MANET). This is accomplished through a reactive IPv4‐based routing protocol built on top of the MAC 802.11b layer. We further present our simulated results and perform a comparative analysis against other epidemic routing protocols such as SIR and SEIR. We discover our model performing better in terms of most performance metrics.
An optimized trusted‐cluster–based routing in disruption‐tolerant network using experiential learning model
Authors: Juyal Vandana , Saggar Ravish , Pandey Nitin
Published: October 2019

Disruption‐tolerant network (DTN) implementation is subject to many routing constraints like limited knowledge of the network and intermittent connections with no end‐to‐end path existence. In this paper, the researchers propose trusted‐cluster–based routing protocol (TCR) for routing in DTN. TCR uses the experiential learning model that integrates neural network‐based bipolar sigmoid activation function to form trusted‐cluster DTN. TCR works in two phases: firstly to form a trusted‐cluster and secondly to identify cluster heads to direct network traffic through them. After the formation of the trusted‐cluster, a cluster head is chosen for a set period, thus instigating stability in the network. These trust values are attached to the node's route cache to make competitive routing decisions by relaying a message to the other trusted intermediate nodes only. With negative trust value, any node is deprived of participation in the network. This way, TCR eliminates malicious or selfish nodes to participate in the DTN network and minimizes the number of messages forwarded in a densely populated DTN. Also, this implementation conserves sufficient buffer memory to reach the destined node. The TCR's performance with other DTN routing schemes, namely, epidemic and trust‐based routing, is compared using multiple simulations runs. The proposed work is verified using mobility traces from Community Resource for Archiving Wireless Data At Dartmouth, and the experimental result shows the elimination of selfish nodes participating in the DTN. The simulation result shows an increase of 19% in message delivery by forwarding only to a trusted intermediate node possible.
Online CQI‐based optimization using k‐means and machine learning approach under sparse system knowledge
Authors: Shah Brijesh , Dalwadi Gaurav , Pandey Anupkumar , Shah Hardip , Kothari Nikhil
Published: October 2019

Modern cellular mobile networks are becoming more complicated and too expensive in terms of deployment, operation, and maintenance. Traffic demand in cellular networks typically experiences spatio‐temporal variations because of users' mobility and usage behaviour, which lead some of the cells to get overloaded without fully utilizing network capacity. To tackle these challenges, nowadays, self‐organizing networks (SONs) become an essential feature. This paper offers the development of an optimization framework for SONs based on channel quality indicator (CQI) and loading condition without detail knowledge of the network environment. Since the electrical tilt plays a key role in optimizing both coverage and capacity, the main motive is to ensure efficient network operation by electrical tilt‐based radio frequency (RF) performance optimization using a machine learning approach. This novel methodology shows two‐step optimization algorithms: (a) cluster formation based on handover success rate using k‐means algorithm and (b) reinforcement learning‐based optimization. Simulation and field trial shows that the proposed approach provides better results than the conventional method of prediction using genetic algorithm (GA) and other online approaches.
Stateful firewall‐enabled software‐defined network with distributed controllers: A network performance study
Authors: Prabakaran Senthil , Ramar Ramalakshmi
Published: October 2019

SummarySoftware‐defined network (SDN) is constructed by decoupling the control and data plane from the forwarding devices. The control plane operations are managed by centralized or distributed controllers, and the data plane operation is managed by respective forwarding devices. SDN provides an easy and efficient management solutions for software‐programmed consolidated middlebox in virtual machines. Additionally, SDN with centralized controller faces complications like scalability, network bottle neck, and single point failure. In this study, a stateful inspection firewall acts as a middlebox in distributed SDN‐controlled network. The controller is programmed with a failure detection and recovery mechanism to provide reliability and redundancy and enhance the overall performance of the network. The objective of stateful firewall on SDN architecture is to secure the network by monitoring the current connections and maintain its state information until the connection is active. In this paper, the performance of firewall‐enabled SDN with centralized and distributed controllers are measured, compared, and analyzed. The experiments are done using POX controller, and the results are verified by Mininet network emulation tool. The results show that the stateful firewall‐enabled SDN with distributed controller network improves the security, reliability, availability, and overall performance of the network. In the proposed SDN, average network throughput is improved by 43%, average network delay is reduced by 4%, average channel utilization is increased by 40%, average network overhead is reduced by 26%, and average network response time is reduced by 23%.
Threshold peat burn severity breaks evaporation‐limiting feedback
Authors: Wilkinson Sophie L. , Verkaik Gregory J. , Moore Paul A. , Waddington James M.
Published: October 2019

A suite of autogenic ecohydrological feedbacks and moss traits are important for protecting vast peatland carbon stocks following wildfire disturbance. Here, we examine how peat burn severity and water table depth (WTD) affect the strength of one such feedback—the hydrophobicity–evaporation feedback (HEF). The HEF is an evaporation‐limiting feedback known to minimize water loss following wildfire. The peatland surface becomes hydrophobic creating an evaporative cap and thereby reducing post‐fire evaporation; however, recent studies hypothesize that this is dependent on peat burn severity. To test this hypothesis, we studied plots along a peat burn severity gradient in a partially drained black spruce peatland that burned during the 2016 Fort McMurray Horse River wildfire. Evaporation rates were significantly lower in plots where hydrophobicity was present. Hydrophobicity was lowest in the severely burned area, and the average instantaneous evaporation rate (2.75 mm day−1) was significantly higher than moderately and typical‐lightly burned areas (0.82 and 1.64 mm day−1, respectively). Based on lab results, increasing WTD affected hydrophobicity within lightly burned (singed) feather moss samples but not in heavily burned feather moss, showing the importance of post‐fire ground cover and in situ WTD. Our results provide evidence of a burn severity threshold where increased depth of burn removes the feather moss evaporative cap and causes the HEF to break down. We argue that this threshold has important implications for boreal peatlands, which are predicted to undergo climate‐mediated pre‐fire drying and increasing burn severities, potentially leading to further carbon losses due to enhanced post‐fire drying and concomitant decomposition.
Synthesis and Catalytic Evaluation of Phosphanylferrocene Ligands with Cationic Guanidinium Pendants and Varied Phosphane Substituents
Authors: Bárta Ondřej , Císařová Ivana , Mieczyńska Ewa , Trzeciak Anna M. , Štěpnička Petr
Published: October 2019

This contribution expands the still narrow class of functional ferrocene phosphanes with polar cationic groups, focusing on the synthesis and catalytic use of a series of phosphanylferrocene ligands bearing positively charged guanidinium tags, [R2PfcCH2NHC(NH2)2]Cl (3a–d), where fc = ferrocene‐1,1′‐diyl, R = isopropyl (a), cyclohexyl (b), phenyl (c), and 2‐furyl (d). To probe the influence of phosphane substituents, these compounds were studied as supporting ligands in Pd‐catalyzed Suzuki–Miyaura cross‐coupling of acyl chlorides with arylboronic acids, in analogous coupling of aryl bromides with arylboronic acids, and in Rh‐catalyzed hydroformylation of 1‐hexene using trans‐[RhCl(CO){R2PfcCH2NHC(NH2)2‐κP}2]Cl2 complexes (4a–d) as pre‐catalysts. The outcome of the cross‐coupling reactions strongly depended on the starting materials, and no ligand generated a universally applicable catalyst when combined with Pd(OAc)2. In the hydroformylation reactions, the catalyst based on 4d led to lower conversions than all others, which performed rather similarly. Overall, the phenyl‐substituted phosphane 3c emerged as a good compromise, giving rise to reasonably efficient and stable catalysts in most cases (except for Suzuki–Miyaura biaryl cross‐couplings, wherein electron‐rich alkylphosphanes performed better than 3c).
Carbonylative Negishi‐Type Coupling of 2‐Iodoglycals with Alkyl and Aryl Halides
Authors: Esteves Henrique A. , Darbem Mariana P. , Pimenta Daniel C. , Stefani Hélio A.
Published: October 2019

C‐Glycosides are valuable organic compounds in the field of medicinal chemistry due to their ubiquity inside living systems and pronounced biological activity. Herein, we describe an approach to alkyl‐ketones bearing glycal units via the Pd‐catalyzed carbonylative coupling of 2‐iodoglycals and alkyl and aryl halides. Examples bearing a variety of functional groups are presented as well as a mechanistic proposal for this transformation.
Flow Chemistry: Towards A More Sustainable Heterocyclic Synthesis
Authors: Brandão Pedro , Pineiro Marta , Pinho e Melo Teresa M. V. D.
Published: October 2019

Flow Chemistry is a revolutionary field in Organic Chemistry. By changing the conventional methods and apparatus applied in the chemical synthesis, flow chemistry emerges as a game changer for organic synthesis laboratories, in both academia and industries. Considered as a sustainable practice, flow processes play an important role in the development of fine chemical products and in drug discovery development programs. This work aims to review the recent contributions on heterocyclic synthesis under continuous‐flow conditions, focusing in heterocycle ring formation and highlighting some of the most recent examples found in the literature, as well as some synthetic strategies aiming for the flow preparation of high‐value chemical products, such as APIs and agrochemicals.
Lewis Base Catalysis Promoted Nucleophilic Substitutions – Recent Advances and Future Directions
Authors: Huy Peter H.
Published: October 2019

Nucleophilic substitutions (SN) account for the most essential and frequently applied chemical transformations. SN‐reactions allow forging C–C, C–O, C–N and C–Cl bonds, for example, from natural abundant starting materials such as alcohols and carboxylic acids. Products of SN‐reactions are ubiquitous and find inter alia applications as pharmaceuticals, plant protection agents and polymers. However, conventional SN‐type approaches are restricted frequently by the necessity of hazardous reagents and by‐products, a poor waste‐balance and therefore sustainability and high levels of costs, which especially impedes application in large scale synthesis. In order to provide solutions to these limitations, the development of novel catalytic methods for SN‐transformations has evolved into a flourishing and reviving area of research. The current review enables an overview of modern strategies for catalytic nucleophilic substitutions, presents as main topic the state‐of‐the‐art with respect to SN‐methods that are promoted by Lewis bases and points out potential future directions for further innovations.
Rapid pre‐concentration of Escherichia coli in a microfluidic paper‐based device using ion concentration polarization
Authors: Perera A.T.K. , Pudasaini Sanam , Ahmed Syed Shaheer Uddin , Phan Dinh‐Tuan , Liu Yu , Yang Chun
Published: October 2019

We report a microfluidic paper based analytical device implementing ion concentration polarization (ICP) for rapid pre‐concentration of Escherichia coli in water. The fabricated device consists of a paper channel with a Nafion® membrane and in‐built micro wire electrodes to supply electric voltage to induce the ICP effect. E. coli cells were stained with SYTO 9 and fluorescence was used as a sensing method. The device achieved high concentration factor up to 2 × 105 within minutes. The effect of total ion concentration, on ICP and fluorescence intensity was studied. The reported device and method are suitable and effective for detection of E. coli during ballast water quality monitoring, coastal water quality monitoring where high salinity water is present.
Image and command hybrid model for vehicle control using Internet of Vehicles
Authors: Malik Kaleem Razzaq , Ahmad Mughees , Khalid Shehzad , Ahmad Haseeb , Al‐Turjman Fadi , Jabbar Sohail
Published: October 2019

The growing volume of traffic generates the ultimate challenge on the research for traffic control. Vehicle automation is getting closer to reality due to the massive mobile communication capacity provided by fifth‐generation (5G) wireless sensor networks (WSNs). Nowadays, manually controlling and monitoring vehicles at traffic rush hours is becoming difficult for safety control. Thus, the present condition requires providing control services and devices, which are functioning in real‐time worldwide mode through soft Internet of Vehicles (IoV) services over a software‐defined network (SDN). The SDN makes software integration and progress monitoring much easier and convenient. This article focuses on WSN‐based vehicle automation following controlling and observation through speech recognition and image processing. The article also demonstrates the working prototype of the proposed mechanism to automatically drive a car and to detect obstacles through voice and image‐based deep learning, respectively. Moreover, obstacle detection on the road is a major concern in vehicle controlling systems. The system detects every obstacle on roads using cameras mounted to cover the view for driver assistance. Once the obstacle found, it generates alert for the driver to stop a collision. All these experiments require a high‐speed communication platform for evaluations. A case study is used on vehicle observation and controlling using speech commands and image processing with real‐world on‐road vehicle data sets.
Case‐control versus case‐only estimates of gene‐environment interactions with common and misclassified clinical diagnosis
Authors: Lobach Iryna , Sheng Ying , Lobach Siarhei , Zablotska Lydia , Huang Chiung‐Yu
Published: October 2019

Genetic studies provide valuable information to assess if the effect of genetic variants varies by the nongenetic “environmental” variables, what is traditionally defined to be gene–environment interaction (GxE). A common complication is that multiple disease states present with the same set of symptoms, and hence share the clinical diagnosis. Because (a) disease states might have distinct genetic bases; and (b) frequencies of the disease states within the clinical diagnosis vary by the environmental variables, analyses of association with the clinical diagnosis as an outcome variable might result in false positive or false negative findings. We develop estimates for this setting to be able to assess GxE in a case‐only study and we compare the case‐control and case‐only estimates. We report extensive simulation studies that evaluate empirical properties of the estimates and show the application to a study of Alzheimer's disease.