bluuebunny/crossref_metadata_2025 huggingface dataset:
Tandem riboswitches form a natural Boolean logic gate to control purine metabolism in bacteria
Authors: Sherlock Madeline E , Sudarsan Narasimhan , Stav Shira , Breaker Ronald R
Published: March 2018

Gene control systems sometimes interpret multiple signals to set the expression levels of the genes they regulate. In rare instances, ligand-binding riboswitch aptamers form tandem arrangements to approximate the function of specific two-input Boolean logic gates. Here, we report the discovery of riboswitch aptamers for phosphoribosyl pyrophosphate (PRPP) that naturally exist either in singlet arrangements, or occur in tandem with guanine aptamers. Tandem guanine-PRPP aptamers can bind the target ligands, either independently or in combination, to approximate the function expected for an IMPLY Boolean logic gate to regulate transcription of messenger RNAs for de novo purine biosynthesis in bacteria. The existence of sophisticated all-RNA regulatory systems that sense two ancient ribonucleotide derivatives to control synthesis of RNA molecules supports the hypothesis that RNA World organisms could have managed a complex metabolic state without the assistance of protein regulatory factors.
Genetic diversity and connectivity of the megamouth shark (Megachasma pelagios)
Authors: Liu Shang Yin Vanson , Joung Shoou Jeng , Yu Chi-Ju , Hsu Hua-Hsun , Tsai Wen-Pei , Liu Kwang Ming
Published: March 2018

The megamouth shark (Megachasma pelagios) was described as a new species in 1983. Since then, only ca. 100 individuals have been observed or caught. Its horizontal migration, dispersal, and connectivity patterns are still unknown due to its rarity. Two genetic markers were used in this study to reveal its genetic diversity and connectivity pattern. This approach provides a proxy to indirectly measure gene flow between populations. Tissues from 27 megamouth sharks caught by drift nets off the Hualien coast (eastern Taiwan) were collected from 2013 to 2015. With two additional tissue samples from megamouths caught in Baja California, Mexico, and sequences obtained from GenBank, we were able to perform the first population genetic analyses of the megamouth shark. The mtDNA cox1 gene and a microsatellite (Loc 6) were sequenced and analyzed. Our results showed that there is no genetic structure in the megamouth shark, suggesting a possible panmictic population. Based on occurrence data, we also suggest that the Kuroshio region, including the Philippines, Taiwan, and Japan, may act as a passageway for megamouth sharks to reach their feeding grounds from April to August. Our results provide insights into the dispersal and connectivity of megamouth sharks. Future studies should focus on collecting more samples and conducting satellite tagging to better understand the global migration and connectivity pattern of the megamouth shark.
Salinification in the South China Sea Since Late 2012: A Reversal of the Freshening Since the 1990s
Authors: Zeng Lili , Chassignet Eric P. , Schmitt Raymond W. , Xu Xiaobiao , Wang Dongxiao
Published: March 2018

Salinification has occurred in the South China Sea from late 2012 to the present, as shown by satellite Aquarius/Soil Moisture Active Passive data and Argo float data. This salinification follows a 20 year freshening trend that started in 1993. The salinification signal is strongest near the surface and extends downward under the seasonal thermocline to a depth of 150 m. The salinification occurs when the phase of the Pacific Decadal Oscillation switches from negative to positive. Diagnosis of the salinity budget suggests that an increasing net surface freshwater loss and the horizontal salt advection through the Luzon Strait driven by the South China Sea throughflow contributed to this ongoing salinification. In particular, a decrease in precipitation and enhanced Luzon Strait transport dominated the current intense salinification. Of particular interest is whether this salinification will continue until it reaches the previous maximum recorded in 1992.
Solar Wind Deflection by Mass Loading in the Martian Magnetosheath Based on MAVEN Observations
Authors: Dubinin E. , Fraenz M. , Pätzold M. , Halekas J. S. , Mcfadden J. , Connerney J. E. P. , Jakosky B. M. , Vaisberg O. , Zelenyi L.
Published: March 2018

Mars Atmosphere and Volatile EvolutioN observations at Mars show clear signatures of the shocked solar wind interaction with the extended oxygen atmosphere and hot corona displayed in a lateral deflection of the magnetosheath flow in the direction opposite to the direction of the solar wind motional electric field. The value of the velocity deflection reaches ∼50 km/s. The occurrence of such deflection is caused by the “Lorentz‐type” force due to a differential streaming of the solar wind protons and oxygen ions originating from the extended oxygen corona. The value of the total deceleration of the magnetosheath flow due to mass loading is estimated as ∼40 km/s.
Anthropogenic Signatures of Lead in the Northeast Atlantic
Authors: Rusiecka D. , Gledhill M. , Milne A. , Achterberg E. P. , Annett A. L. , Atkinson S. , Birchill A. , Karstensen J. , Lohan M. , Mariez C. , Middag R. , Rolison J. M. , Tanhua T. , Ussher S. , Connelly D.
Published: March 2018

Anthropogenic activities have resulted in enhanced lead (Pb) emissions to the environment over the past century, mainly through the combustion of leaded gasoline. Here we present the first combined dissolved (DPb), labile (LpPb), and particulate (PPb) Pb data set from the Northeast Atlantic (Celtic Sea) since the phasing out of leaded gasoline in Europe. Concentrations of DPb in surface waters have decreased by fourfold over the last four decades. We demonstrate that anthropogenic Pb is transported from the Mediterranean Sea over long distances (>2,500 km). Benthic DPb fluxes exceeded the atmospheric Pb flux in the region, indicating the importance of sediments as a contemporary Pb source. A strong positive correlation between DPb, PPb, and LpPb indicates a dynamic equilibrium between the phases and the potential for particles to “buffer” the DPb pool. This study provides insights into Pb biogeochemical cycling and demonstrates the potential of Pb in constraining ocean circulation patterns.
Opening of the South China Sea and Upwelling of the Hainan Plume
Authors: Yu Mengming , Yan Yi , Huang Chi‐Yue , Zhang Xinchang , Tian Zhixian , Chen Wen‐Huang , Santosh M.
Published: March 2018

Opening of the South China Sea and upwelling of the Hainan Plume are among the most challenging issues related to the tectonic evolution of East Asia. However, when and how the Hainan Plume affected the opening of the South China Sea remains unclear. Here we investigate the geochemical and isotopic features of the ~25 Ma mid‐ocean ridge basalt (MORB) in the Kenting Mélange, southern Taiwan, ~16 Ma MORB drilled by the IODP Expedition 349, and ~9 Ma ocean island basalt‐type dredged seamount basalt. The ~25 Ma MORBs reveal a less metasomatic depleted MORB mantle‐like source. In contrast, the Miocene samples record progressive mantle enrichment and possibly signal the contribution of the Hainan Plume. We speculate that MORBs of the South China Sea which could have recorded plume‐ridge source mixing perhaps appear since ~23.8 Ma. On the contrary, the Paleocene‐Eocene ocean island basalt‐type intraplate volcanism of the South China continental margin is correlated to decompression melting of a passively upwelling fertile asthenosphere due to continental rifting.
Pitch Angle Dependence of Energetic Electron Precipitation: Energy Deposition, Backscatter, and the Bounce Loss Cone
Authors: Marshall R. A. , Bortnik J.
Published: March 2018

Quantifying radiation belt precipitation and its consequent atmospheric effects requires an accurate assessment of the pitch angle distribution of precipitating electrons, as well as knowledge of the dependence of the atmospheric deposition on that distribution. Here Monte Carlo simulations are used to investigate the effects of the incident electron energy and pitch angle on precipitation for bounce period time scales, and the implications for both the loss from the radiation belts and the deposition in the upper atmosphere. Simulations are conducted at discrete energies and pitch angles to assess the dependence on these parameters of the atmospheric energy deposition profiles and to estimate the backscattered particle distributions. We observe that the atmospheric response is both energy and pitch angle dependent. These effects together result in an energy‐dependent bounce loss cone angle, which can vary by 2–3° with particle energy when considered at low‐Earth orbit. This modeling also predicts that a significant fraction of the input electron distribution will be backscattered and should be observable by low‐Earth‐orbiting satellites as field‐aligned beams emerging from the atmosphere at energies lower than the input distribution and having pitch angles distributed just inside the loss cone.
Weak Cooling of Cold Extremes Versus Continued Warming of Hot Extremes in China During the Recent Global Surface Warming Hiatus
Authors: Shen Xiangjin , Liu Binhui , Lu Xianguo
Published: March 2018

Using daily maximum temperature (Tmax), minimum temperature (Tmin), and mean temperature data of 437 weather stations in China, we compared variations of the mean with extreme ends of probability distribution of temperatures in China from 1960 to 2015. Our analysis confirmed that annual mean Tmax and Tmin experienced warming hiatus in China after 1998. The warming hiatus is also reflected by the weak cooling of cold extremes across China, but hot extremes continue the significant warming trend nationally and in climate regions of East China, Southwest China, and the Tibetan Plateau. During 1999–2015, the hot day frequency (Tx90, based on base period 1961–1990) and averaged Tmax above the 90th percentile of each year (Txp90) increased significantly by 3.70 d/decade and 0.20°C/decade nationally. But there were significant cooling trends of cold extremes in East China and Southeast China from 1999 to 2015. During the warming hiatus period, the obvious decline in warm season precipitation contributed to the ongoing warming of hot extremes in East China and Southwest China. Both the decrease of warming season solar irradiance and increase of warm season precipitation facilitated the weak cooling trends of hot extremes in Northeast China and North China Plain. Although mean temperature experienced warming hiatus after 1998, the continued warming of hot extremes and reverse from warming to weak cooling of cold extremes imply an increase of temperature variability in China simultaneously.
The Cloud Top Distribution and Diurnal Variation of Clouds Over East Asia: Preliminary Results From Advanced Himawari Imager
Authors: Chen Dandan , Guo Jianping , Wang Hongqing , Li Jian , Min Min , Zhao Wenhui , Yao Dan
Published: March 2018

Clouds, as one of the most uncertain factors in climate system, have been intensively studied as satellites with advanced instruments emerged in recent years. However, few studies examine the vertical distributions of cloud top and their temporal variations over East Asia based on geostationary satellite data. In this study, the vertical structures of cloud top and its diurnal variations in summer of 2016 are analyzed using the Advanced Himawari Imager/Himawari‐8 cloud products. Results show that clouds occur most frequently over the southern Tibetan Plateau and the Bay of Bengal. We find a steep gradient of cloud occurrence frequency extending from southwest to northeast China and low‐value centers over the eastern Pacific and the Inner Mongolia Plateau. The vertical structures of cloud top are highly dependent on latitude, in addition to the nonnegligible roles of both terrain and land‐sea thermal contrast. In terms of the diurnal cycle, clouds tend to occur more often in the afternoon, peaking around 1700 local time over land and ocean. The amplitude of cloud diurnal variation over ocean is much smaller than that over land, and complex terrain tends to be linked to larger amplitude. In vertical, the diurnal cycle of cloud frequency exhibits bimodal pattern over both land and ocean. The high‐level peaks occur at almost the same altitude over land and ocean. In contrast, the low‐level peaks over ocean mainly reside in the boundary layer, much lower than those over land, which could be indicative of the frequent occurrence of marine boundary layer clouds.
Meridional Contrasts in Productivity Changes Driven by the Opening of Drake Passage
Authors: Ladant Jean‐Baptiste , Donnadieu Yannick , Bopp Laurent , Lear Caroline H. , Wilson Paul A.
Published: March 2018

Changes in atmospheric pCO2 are widely suggested to have played a major role in both the long‐term deterioration of Cenozoic climate and many superimposed rapid climate perturbations such as the pivotal Eocene‐Oligocene transition. Changes in marine productivity affecting the biological oceanic carbon pump represent one possible cause of past CO2 variability. Here we explore the relationship between ocean gateway change and marine biogeochemistry. Specifically, we use a fully coupled atmosphere‐ocean‐biogeochemical model (IPSL‐CM5A) to examine global ocean paleoproductivity changes in response to the opening of Drake Passage. In our simulations, we find that Drake Passage opening yields a spatially uniform decrease in primary productivity in the low‐latitude oceans while the high‐latitude response is more spatially heterogeneous. Mechanistically, the low‐latitude productivity decrease is a consequence of a fundamental reorganization of ocean circulation when Drake Passage opens driven by the isolation of the Southern Ocean from low‐latitude water masses. Nutrient depletion in the low latitudes is driven by a marked decrease in the intensity of deep convection in the Southern Ocean, which drives the accumulation of nutrients at depth and their depletion in the intermediate and upper ocean, especially away from sites of subduction. In the high latitudes, the onset of the Antarctic Circumpolar Current in the model exerts a strong control both on nutrient availability and on regions of deep‐water formation. The qualitative agreement between geographically diverse long‐term paleoproductivity records and the simulated variations suggests that Drake Passage opening may contribute to the long‐term paleoproductivity signal.
Dynamical Core in Atmospheric Model Does Matter in the Simulation of Arctic Climate
Authors: Jun Sang‐Yoon , Choi Suk‐Jin , Kim Baek‐Min
Published: March 2018

Climate models using different dynamical cores can simulate significantly different winter Arctic climates even if equipped with virtually the same physics schemes. Current climate simulated by the global climate model using cubed‐sphere grid with spectral element method (SE core) exhibited significantly warmer Arctic surface air temperature compared to that using latitude‐longitude grid with finite volume method core. Compared to the finite volume method core, SE core simulated additional adiabatic warming in the Arctic lower atmosphere, and this was consistent with the eddy‐forced secondary circulation. Downward longwave radiation further enhanced Arctic near‐surface warming with a higher surface air temperature of about 1.9 K. Furthermore, in the atmospheric response to the reduced sea ice conditions with the same physical settings, only the SE core showed a robust cooling response over North America. We emphasize that special attention is needed in selecting the dynamical core of climate models in the simulation of the Arctic climate and associated teleconnection patterns.
Thermal Properties of Intermetallic Phases at the Interface of Aluminum–Copper Compound Castings
Authors: Klose Christian , Freytag Patrik , Otten Maik , Thürer Susanne Elisabeth , Maier Hans Jürgen
Published: March 2018

High‐pressure die compound casting relies on high bond quality, and high thermal contact conductance at the interface is a key issue in the context of cast advanced cooling components, such as lightweight heat sinks for desktop and portable computers. The current study aims at enhancing the thermal contact between a copper insert piece and an AlSi9Cu3(Fe) cast alloy by developing suitable Zn‐based coatings, which are used to establish a firm metallurgical bond between the solid insert and the cast alloy during high‐pressure die‐casting. It is demonstrated by microstructural analyses that various phases form at the interfaces in the casting process. As the thermal conductivities of these phases have not been available, these are determined individually using a thermoflash device. The SEM investigations indicate that mainly ternary phases of the type AlxCuyZnz emerge in the bonding zone, as the high casting temperatures promote the diffusion of aluminum atoms into the coating. Interestingly, an alloy containing 50 wt% zinc reaches a thermal conductivity as high as 166 W mK−1. The microstructural characteristic at the interfaces and the ramifications with respect to applications are discussed.
Surface‐Enhanced Raman Scattering for Rapid Detection and Characterization of Antibiotic‐Resistant Bacteria
Authors: Galvan Daniel D. , Yu Qiuming
Published: March 2018

As the prevalence of antibiotic‐resistant bacteria continues to rise, biosensing technologies are needed to enable rapid diagnosis of bacterial infections. Furthermore, understanding the unique biochemistry of resistance mechanisms can facilitate the development of next generation therapeutics. Surface‐enhanced Raman scattering (SERS) offers a potential solution to real‐time diagnostic technologies, as well as a route to fundamental, mechanistic studies. In the current review, SERS‐based approaches to the detection and characterization of antibiotic‐resistant bacteria are covered. The commonly used nanomaterials (nanoparticles and nanostructured surfaces) and surface modifications (antibodies, aptamers, reporters, etc.) for SERS bacterial detection and differentiation are discussed first, and followed by a review of SERS‐based detection of antibiotic‐resistant bacteria from environmental/food processing and clinical sources. Antibiotic susceptibility testing and minimum inhibitory concentration testing with SERS are then summarized. Finally, recent developments of SERS‐based chemical imaging/mapping of bacteria are reviewed.
Graphene Materials in Antimicrobial Nanomedicine: Current Status and Future Perspectives
Authors: Karahan Hüseyin Enis , Wiraja Christian , Xu Chenjie , Wei Jun , Wang Yilei , Wang Liang , Liu Fei , Chen Yuan
Published: March 2018

Graphene materials (GMs), such as graphene, graphene oxide (GO), reduced GO (rGO), and graphene quantum dots (GQDs), are rapidly emerging as a new class of broad‐spectrum antimicrobial agents. This report describes their state‐of‐the‐art and potential future covering both fundamental aspects and biomedical applications. First, the current understanding of the antimicrobial mechanisms of GMs is illustrated, and the complex picture of underlying structure–property–activity relationships is sketched. Next, the different modes of utilization of antimicrobial GMs are explained, which include their use as colloidal dispersions, surface coatings, and photothermal/photodynamic therapy agents. Due to their practical relevance, the examples where GMs function as synergistic agents or release platforms for metal ions and/or antibiotic drugs are also discussed. Later, the applicability of GMs in the design of wound dressings, infection‐protective coatings, and antibiotic‐like formulations (“nanoantibiotics”) is assessed. Notably, to support our assessments, the existing clinical applications of conventional carbon materials are also evaluated. Finally, the key hurdles of the field are highlighted, and several possible directions for future investigations are proposed. We hope that the roadmap provided here will encourage researchers to tackle remaining challenges toward clinical translation of promising research findings and help realize the potential of GMs in antimicrobial nanomedicine.
A Broadband Compatible Multispectral Metamaterial Absorber for Visible, Near‐Infrared, and Microwave Bands
Authors: Li Meiling , Muneer Badar , Yi Zixuan , Zhu Qi
Published: March 2018

A design of a compatible multispectral metamaterial absorber with broadband and strong absorption in the microwave, visible‐light, and near‐infrared bands is presented based on conductive carbon black (CCB)‐filled polyethylene (PE) composite films. The CCB‐filled PE composite films are employed to not only attenuate the light energy for realizing visible and near‐infrared absorbers, but also provide a conductive film to construct resistive metamaterial surfaces for realizing a microwave absorber. Considering the two natural properties of the composite films, light attenuation property and electric property, a multilayered structure based on resistive metamaterial surfaces is designed to realize a broadband compatible absorber. These resistive metamaterial surface layers are realized by the prepared composite films. The effect of different resistances of resistive metamaterial surfaces, polarization, and incident angles on the microwave absorbing performance is also analyzed in detail. Finally, a compatible multispectral absorber with a total thickness of 17 mm (0.133λmax) is fabricated and measured. Simulated and measured results both show that the presented absorber can achieve an absorption of 96.8% over a frequency range from 2.35 to 18 GHz. On the other hand, a high absorption of about 95% is obtained in visible‐light and near‐infrared bands as well.
Tunable Emission Color and Morphology of Organic Microcrystals by a “Cocrystal” Approach
Authors: Wu Jun‐Jie , Li Zhi‐Zhou , Zhuo Ming‐Peng , Wu Yuchen , Wang Xue‐Dong , Liao Liang‐Sheng , Jiang Lei
Published: March 2018

Organic cocrystals formed with two or more different molecules through intermolecular noncovalent interactions, such as π–π interaction and hydrogen/halogen bonds, have received increasing attention due to their promising applications in organic optoelectronics. For organic photonics and electronics, the growth morphology of organic micro/nanocrystals coupled with their shape and emission color is of great importance. In this study, using a “cocrystal” approach, the organic microcrystals can be modulated from the yellow‐emissive polyhedral microcrystals of 1,4‐bis (4‐cyanostyryl) benzene (p‐BCB) to the sky‐blue‐emissive microwires ofp‐BCB:1,4‐diiodo tetrafluorobenzene (p‐BCB:DIFB), which are self‐assembled in solution at room temperature. Additionally, with the formation of the cocrystals, the radiative decay (kr) rate of these organic microcrystals is enhanced from 0.04 to 0.12 ns−1, which is attributed to the absence of excimers in the organic cocrystals. Therefore, this “cocrystal” approach can simultaneously tune the emission color, morphology, and molecular packing mode of these as‐prepared organic microcrystals, which can contribute to the development of organic integrated optoelectronic devices.
Organocatalytic Enantioselective aza‐Friedel‐Crafts Reactions of Pyrazolinone Ketimines with Hydroxyindoles and Electron‐Rich Phenols
Authors: Yang Zhong‐Tao , Yang Wu‐Lin , Chen Long , Sun Hao , Deng Wei‐Ping
Published: March 2018

A variety of enantioenriched indole derivatives substituted in the benzene ring were synthesised via an organocatalytic asymmetric aza‐Friedel‐Crafts reaction of pyrazolinone ketimines with hydroxyindoles. This reaction was also applicabled to electron‐rich phenols, yielding the desired products in high yields (up to 99%) and excellent stereo‐selectivities (91–99% ee). Moreover, this method presents its potential in the synthesis of structurally novel indole‐pyrazolinone conjugate derivatives.

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Timing is everything: Dichogamy and pollen germinability underlie variation in autonomous selfing among populations
Authors: Koski Matthew H. , Kuo Liao , Niedermaier Kerstin M. , Galloway Laura F.
Published: March 2018

Premise of the Study

The evolution of multiple floral traits often underlies the transition from outcrossing to selfing. Such traits can influence the ability to self, and the timing at which selfing occurs, which in turn affects the costs of selfing. Species that display variation in autonomous selfing provide an opportunity to dissect the phenotypic changes that contribute to variability in the mating system.

Methods

In a common garden, we measured dichogamy and herkogamy in 24 populations of the protandrous mixed‐mating herb Campanula americana, and related these to autonomous fruit set (autonomy). We then measured the timing of self‐pollen deposition and fruit production in populations with high and low autonomy, and determined whether pollen germinability across floral development contributes to variation in autonomy.

Key Results

Populations that transitioned more rapidly to female phase displayed elevated autonomous selfing, but herkogamy was unassociated with autonomous selfing. Selfing occurred more rapidly in highly autonomous populations because of greater self‐pollen deposition early in female phase. Pollen germinability in low‐autonomy populations remained constant across floral development, but in high‐autonomy populations it increased after floral anthesis and was highest near the onset of female phase.

Conclusions

Reduced dichogamy, elevated self‐pollen deposition, and higher pollen germination late in male phase contribute to both earlier selfing and greater selfing. These traits vary among populations, likely reflecting past selection on the mating system. While delayed selfing bears fewer fitness costs, the evolution of earlier selfing may be favored if self‐pollen availability decreases over floral development.
Sequential Ytterbium(III) Triflate Catalyzed One‐Pot Three‐Component Thia‐Michael Addition
Authors: Huang Hsin‐Yi , Liang Chien‐Fu
Published: March 2018

A ytterbium(III) trifluoromethanesulfonate catalyzed one‐pot three‐component thia‐Michael addition reaction of thiolate salts, organic halides, and α,β‐unsaturated compounds has been developed for the formation of carbon‐sulfur bonds. In this study, potassium thioacetate serves as the sulfur source in a nucleophilic substitution reaction, which is followed by a Yb(OTf)3‐catalyzed (OTf=trifluoromethanesulfonate) S‐deacetylation and subsequent thia‐Michael addition reaction. Three important pharmaceutical derivatives were successfully prepared by using the intramolecular version of this one‐pot thia‐Michael addition reaction. The advantages of this YbIII‐catalyzed process include its operational simplicity, its capacity towards the preparation of structurally diverse products in 40–93 % yield, its use of relatively low toxic or nontoxic reagents, and its catalyst loading of only 1–2 mol %.
The Stapedial Artery in the Mongolian Gerbil (Meriones unguiculatus)
Authors: Kuchinka Jacek
Published: March 2018

The persistent stapedial artery is a component of the main arterial roads of the head in some animal groups (Frąckowiak: Roczn Akad Roln Poznań 336 (2003) 1–81). This type of vascularization occurs in the Mongolian gerbil, among others. The stapedial artery is common in a variety of forms in rodents. It has been described, for example, in Sciuridae, Muridae, Heteromyidae, Geomyidae, Splacidae, Cricetidae, Arvicolinae, and in genus Jaculus (Cox and Hautier: Evolution of the Rodents: Advances in phylogeny, Functional Morphology and Development, 2015). The aim of this study was the analysis of morphology, and of course, of the stapedial artery in this species. Investigations were performed on 10 animals of both sexes, weighing 50–60 g. After lethal anesthesia, the vascular system of every animal was filled with colored latex. After latex coagulation and decalcification of skull bones, fixed tissues were delicately prepared, and the head vascular system was exposed. The stapedial artery separates from the internal carotid artery, runs toward the auditory bulb and passes through the stapes. After the branching of the medial meningeal artery, the stapedial artery runs rostrally, forming its infraorbital branch. This branch, in the further course, gives the branch forming the short trunk of the ophthalmic artery, which supplies orbital structures (muscles, lacrimal gland, Harderian gland, and eyeball). The performed investigations revealed that the maintained infraorbital branch of the stapedial artery is the only source of arterial supply of the orbit in this species. Anat Rec, 301:1131–1137, 2018. © 2018 Wiley Periodicals, Inc.
A Natural Glycyrrhizic Acid‐Tailored Light‐Responsive Gelator
Authors: Fang Heshu , Zhao Xia , Lin Yuan , Yang Song , Hu Jun
Published: March 2018

The construction of stimuli‐responsive materials by using naturally occurring molecules as building blocks has received increasing attention owing to their bioavailability, biocompatibility, and biodegradability. Herein, a symmetrical azobenzene‐functionalized natural glycyrrhizic acid (trans‐GAG) was synthesized and could form stable supramolecular gels in DMSO/H2O and MeOH/H2O. Owing to trans–cis isomerization, this gel exhibited typical light‐responsive behavior that led to a reversible gel–sol transition accompanied by a variation in morphology and rheology. Additionally, this trans‐GAG gel displayed a distinct injectable self‐healing property and outstanding biocompatibility. This work provides a simple yet rational strategy to fabricate stimuli‐responsive materials from naturally occurring, eco‐friendly molecules.
Pseudohalogenogermylenes versus Halogenogermylenes: Difference in their Complexation Behavior towards Group 6 Metal Carbonyls
Authors: Sharma Mahendra Kumar , Sinhababu Soumen , Yadav Dhirendra , Mukherjee Goutam , Rajaraman Gopalan , Nagendran Selvarajan
Published: March 2018

Pseudohalogenogermylenes [(iBu)2ATI]GeY (Y=NCO 4, NCS 5) show different coordination behavior towards group 6 metal carbonyls in comparison to the corresponding halogenogermylenes [(iBu)2ATI]GeX (X=F 1, Cl 2, Br 3) (ATI=aminotroponiminate). The reactions of compounds 4–5 and 1–3 with cis‐[M(CO)4(COD)] (M=Mo, W, COD=cyclooctadiene) gave trans‐germylene metal complexes {[(iBu)2ATI]GeY}2M(CO)4 (Y=NCO, M=Mo 6, W 11; Y=NCS, M=Mo 7) and cis‐germylene metal complexes {[(iBu)2ATI]GeX}2M(CO)4 (M=Mo, X=F 8, Cl 9, Br 10; M=W, X=Cl 12), respectively. Theoretical studies on compounds 7 and 9 reveal that donor–acceptor interactions from Mo to Ge atoms are better stabilized in the observed trans and cis geometries than in the hypothetical cis and trans structures, respectively.
DNA Conformation Regulates Gene Expression: The MYC Promoter and Beyond
Authors: Zaytseva Olga , Quinn Leonie M.
Published: March 2018

Emerging evidence suggests that DNA topology plays an instructive role in cell fate control through regulation of gene expression. Transcription produces torsional stress, and the resultant supercoiling of the DNA molecule generates an array of secondary structures. In turn, local DNA architecture is harnessed by the cell, acting within sensory feedback mechanisms to mediate transcriptional output. MYC is a potent oncogene, which is upregulated in the majority of cancers; thus numerous studies have focused on detailed understanding of its regulation. Dissection of regulatory regions within the MYC promoter provided the first hint that intimate feedback between DNA topology and associated DNA remodeling proteins is critical for moderating transcription. As evidence of such regulation is also found in the context of many other genes, here we expand on the prototypical example of the MYC promoter, and also explore DNA architecture in a genome‐wide context as a global mechanism of transcriptional control.
Liquid chromatography–tandem MS/MS method for simultaneous quantification of paracetamol, chlorzoxazone and aceclofenac in human plasma: An application to a clinical pharmacokinetic study
Authors: Mohamed Dalia , Hegazy Maha A. , Elshahed Mona S. , Toubar Safaa S. , Helmy Marwa I.
Published: March 2018

A facile, fast and specific method based on liquid chromatography–tandem mass spectrometry (LC–MS/MS) for the simultaneous quantitation of paracetamol, chlorzoxazone and aceclofenac in human plasma was developed and validated. Sample preparation was achieved by liquid–liquid extraction. The analysis was performed on a reversed‐phase C18 HPLC column (5 μm, 4.6 × 50 mm) using acetonitrile–10 mM ammonium formate pH 3.0 (65:35, v/v) as the mobile phase where atrovastatin was used as an internal standard. A very small injection volume (3 μL) was applied and the run time was 2.0 min. The detection was carried out by electrospray positive and negative ionization mass spectrometry in the multiple‐reaction monitoring mode. The developed method was capable of determining the analytes over the concentration ranges of 0.03–30.0, 0.015–15.00 and 0.15–15.00 μg/mL for paracetamol, chlorzoxazone and aceclofenac, respectively. Intraday and interday precisions (as coefficient of variation) were found to be ≤12.3% with an accuracy (as relative error) of ±5.0%. The method was successfully applied to a pharmacokinetic study of the three analytes after being orally administered to six healthy volunteers.
Using open technologies for automatically creating question‐and‐answer sets for engineering MOOCs
Authors: Beg Azam , Beg Ajmal
Published: March 2018

Two of the main challenges faced by today's massive open online courses (MOOCs) are low completion rates and lack of equivalence with the traditional classroom‐based courses. Both of these issues are somewhat related and can be attributed to the assessments which are primarily conducted online and are unsupervised. Enhancing the credibility of the assessment process can lead to higher acceptability of the MOOCs, which in turn is expected to encourage more students to complete the online courses. One way of improving the assessment is providing each online student with a unique set of questions for assignments and examinations. The MOOCs can be taken concurrently by hundreds, if not thousands of students. For such class‐sizes, the manual preparation of distinct questions, especially if they include drawings (e.g., circuit schematics, block diagrams, etc.), is a very daunting proposition due to the required time and effort. To enable the automatic creation of large sets of questions‐and‐answers, we present a system based on open technologies. Although the system currently covers only the circuits‐related courses in Electrical and Computer Engineering, the system's underlying principles are applicable to the conventional/online courses in other fields of engineering and science.
UHPLC‐HRMS/MS Based Profiling of Algerian Lichens and Their Antimicrobial Activities
Authors: Brakni Rafika , Ali Ahmed Monia , Burger Pauline , Schwing Aurélie , Michel Grégory , Pomares Christelle , Hasseine Lillia , Boyer Laurent , Fernandez Xavier , Landreau Anne , Michel Thomas
Published: March 2018

Lichens are complex symbiotic organisms able to produce a vast array of compounds. The Algerian lichen diversity has only prompted little interest even given the 1085 species listed. Herein, the chemodiversity of four Algerian lichens including Cladonia rangiformis, Ramalina farinaceae, R. fastigiata, and Roccella phycopsis was investigated. A dereplication strategy, using ultra high performance liquid chromatography‐high resolution‐electrospray ionization‐mass spectrometry (UHPLC‐HRMS/MS), was carried out for a comprehensive characterization of their substances including phenolics, depsides, depsidones, depsones, dibenzofurans, and aliphatic acids. Some known compounds were identified for the first time in some species. Additionally, the lichenic extracts were evaluated for their antifungal and antimicrobial activities on human pathogenic strains (Candida albicans, C. glabrata, Aspergillus fumigatus, Staphylococcus aureus, and Escherichia coli). Cyclohexane extracts were found particularly active against human pathogenic fungi with MIC80 values ranging from 8 to 62.5 μg/mL, without cytotoxicity. This study highlights the therapeutic and prophylactic potential of lichenic extracts as antibacterial and antifungal agents.
Detection of Taenia saginata infection mimicking Crohn's disease using video capsule endoscopy
Authors: Nussinson Elchanan , Yair‐Sabag Shira , Shibli Fahmi
Published: March 2018

Key Clinical Message

Capsule endoscopy was used to detect intestinal Taenia saginata infection in a 19‐year‐old man. The patient was initially believed to have Crohn's disease due to a notable family history of the disease. Capsule endoscopy is a valuable tool for diagnosing tapeworm infection even when Crohn's disease is suspected.
Blastic plasmacytoid dendritic cell neoplasm
Authors: Rai Manoj Ponadka , Bedi Prabhjot Singh , Kandola Samanjit Kaur , Kavuturu Shilpa , Singhal Rashi
Published: March 2018

Key Clinical Message

Blastic plasmacytoid dendritic cell neoplasm is an aggressive neoplasm with a median survival of only a few months despite treatment. An exhaustive immunohistochemical workup is required to differentiate it from myeloid sarcoma and extranodal NK/T cell lymphoma. Treatment is with induction using a regimen utilized for leukemia. Allogeneic hematopoietic stem cell transplantation is recommended for those who achieve remission following induction.
Nitrogen‐Doped Graphene‐Supported Iron Catalyst for Highly Chemoselective Hydrogenation of Nitroarenes
Authors: Wei Zuojun , Hou Yaxin , Zhu Xinmiao , Guo Liangyu , Liu Yingxin , Zhang Anyun
Published: March 2018

A nitrogen‐doped graphene‐supported iron catalyst was used for the first time in the hydrogenation of a series of nitroarenes to give the corresponding amines with excellent activity and chemoselectivity under mild reaction conditions. Physicochemical characterization of the catalyst by transmission electron microscopy, X‐ray diffraction, X‐ray photoelectron spectroscopy, and Mössbauer spectroscopy revealed the formation of iron particles with an iron oxide core and a metallic iron shell that were coated by a few layers of nitrogen‐doped graphene. The unique structure of FeNx/C in the catalyst was proven to contribute to the hydrogenation activity.
Synergetic Catalysis of Nickel Oxides with Oxygen Vacancies and Nickel Phosphide for the Highly Efficient Hydrodeoxygenation of Phenolic Compounds
Authors: Li Yunhua , Zhao Yafei , Chen Binghui , Wang Wenju
Published: March 2018

The highly efficient hydrodeoxygenation of oxygenated chemicals at a low temperature is a critical issue for biomass crude oil upgrading to reduce equipment and operation expense. The unique electronic features of oxygen vacancies have been found to facilitate deoxygenation above 250 °C. In this work, a series of NiOx/SiO2 catalysts that contain oxygen vacancies was prepared by a sol–gel and controllable temperature‐programmed reduction method. Results show that NiOx/SiO2 has a superior phenol hydrogenation activity in deoxygenation even at 180 °C to Ni2P/SiO2. The high hydrogenation activity derives from the flat adsorption of phenolics over low‐valence Ni cations induced by connected oxygen vacancies. After the introduction of NiOx into Ni2P catalysts, composite NiOx‐Ni2P/SiO2 (0.43≤x<1) bifunctional catalysts demonstrate better phenol hydrodeoxygenation performances under mild reaction conditions in comparison with individual Ni2P and NiOx catalysts and most catalysts presented previously because the coexistence of oxygen vacancies from NiOx and the acidity induced by Ni2P results in the synergistic effect of the adsorption configuration and hydrodeoxygenation ability. Besides, this composite catalyst also has a high activity for the hydrodeoxygenation of different bio‐derived cresol isomers. The reuse test results confirm that oxygen vacancies are relatively stable in comparison with the phosphide.
Millimeter‐Long Vertically Aligned Carbon‐Nanotube‐ Supported Co3O4 Composite Electrode for High‐Performance Asymmetric Supercapacitor
Authors: Yin Yaolong , Xu Yong , Zhou Yu , Yan Ya , Zhan Ke , Yang Junhe , Li Jianqiang , Zhao Bin
Published: March 2018

Cobalt oxide (Co3O4) nanoparticles uniformly anchored on vertically aligned carbon nanotube arrays (VACNTs) are synthesized by means of an effective supercritical carbon dioxide (scCO2) assisted impregnation followed by a thermal annealing process. Benefiting from their desirable 3D nanostructure, the Co3O4/VACNTs (CVN) composites manifest a high specific capacitance of 833 F g−1 at a current density of 1 A g−1 and a good rate capacity with capacitance retention of 89 % even after 20‐fold increase in current density. Coupled with a Fe3O4/VACNTs (FVN) anode (350 F g−1 at 1 A g−1) prepared by the same method, the assembled CVN//FVN asymmetric supercapacitor (ASC) delivers a high energy density of 36 Wh kg−1 (1.65 mWh cm−3) at a power density of 0.93 kW kg−1 (0.05 W cm−3), and a maximum power density of 13.6 kW kg−1 (0.62 W cm−3) at an energy density of 10.6 Wh kg−1 (0.51 mWh cm−3). Moreover, even after 5000 charge‐discharge cycles at a current density of 5 A g−1, the ASC still retains 87 % of its initial specific capacitance. The extraordinary electrochemical performance of the ASC device demonstrates the promise of our VACNTs‐based pseudocapacitive electrode for future energy storage systems.
Spatially Resolved Experiments to Monitor the Singlet Oxygen Initiated Oxidation of Lipid Droplets in Emulsions
Authors: Banerjee Chiranjib , Breitenbach Thomas , Ogilby Peter R.
Published: March 2018

Polyunsaturated fatty acids (PUFAs) are present in lipid systems ranging from cell membranes to food products. Reactive oxygen species (ROS) degrade PUFA‐based lipids, often resulting in undesired consequences. Thus, understanding mechanisms of ROS‐mediated lipid oxidation, including means to inhibit such oxidation, are important. Of significance are oxidation 1) at interfaces in heterogeneous samples, and 2) that may propagate from one lipid droplet to another in an emulsion. We used an optical technique to study spatially resolved aspects of lipid oxidation in oil‐in‐water emulsions. We initiated oxidation using two‐photon photosensitized production of singlet oxygen, O2(a1Δg), confined in a small volume either inside or outside a lipid droplet. The products initially formed (e. g. hydroperoxides) spawned the formation of other ROS (e. g. alkoxyl radicals) that propagated in time and space. We monitored these reactions in imaging experiments using fluorescent probes. Among our results, we demonstrated that the oxidation of one droplet did not appear to spread rapidly to a neighboring droplet. Our observations set the stage for a host of systematic studies.
Model–data fusion approach to quantify evapotranspiration and net ecosystem exchange across the sagebrush ecosystem at different temporal resolutions
Authors: Mitra Bhaskar , Mackay D. Scott , Pendall Elise , Ewers Brent E. , Kwon Hyojung , Cleary Meagan B. , Naithani Kusum J.
Published: March 2018

Evapotranspiration (ET) and net ecosystem exchange (NEE) are driven by both high and slow frequency scalar fluxes. Quantifying the variation of these two processes at different timescales remains a challenge. Bridging this knowledge gap is crucial in order to improve insights of the impact of biotic and abiotic factors modulating these fluxes as well as for accurate estimation of gross primary productivity (GPP) and ecosystem respiration (Re). This issue was addressed using a model–data fusion approach within a Bayesian framework by running the model against ET and NEE observations at three different time steps: subdaily (30 min), daily (1 day), and intermediate (7 days). The model was tested against eddy covariance data collected for a 2‐month period (June and July) from a sagebrush‐steppe ecosystem in the United States. The 95% credible interval (CI) of fast processes such as transpiration and photosynthesis reduced by more than 90% compared with its a priori range when model was run at 30‐min time step. The reduction in CI of the same parameters varied between 30% and 70% when the model was run at 1‐ or 7‐day time step. The 95% CI of slow process such as root respiration reduced by 89% and 73% when model was run at 7‐day and 30‐min time step, respectively. We found strong confidence in predicting ET and NEE at subdaily timescale, whereas uncertainty increased with increase in temporal resolution. GPP and Re varied strongly as the system transitioned from a traditionally wet (June) to a dry (July) month.
Clinical testing of three novel transient receptor potential cation channel subfamily V member 1 antagonists in a pharmacodynamic intradermal capsaicin model
Authors: Sjögren E. , Kullenberg T. , Jonzon B. , Segerdahl M. , Stålberg O. , Halldin M.M. , Sundgren‐Andersson A.K.
Published: March 2018

Background

The transient receptor potential cation channel subfamily V 1 (TRPV1) is involved in nociception and has thus been of interest for drug developers, as a target for novel analgesics. However, several oral TRPV1 antagonists have failed in development, and novel approaches to target TRPV1 with innovative chemistry are needed.

Method

This work describes an intradermal microdosing approach in humans for pharmacodynamic deductions and pharmacological profiling of compounds. First, a human capsaicin model was developed, to generate pharmacodynamic translational data (Study Part A, n = 24). Then, three small molecule TRPV1 antagonists (AZ11760788, AZ12048189 and AZ12099548) were investigated in healthy volunteers (Study Part B, n = 36), applying the established model. Pain and flare were assessed by Visual Analogue Score and laser Doppler, respectively.

Results

The developed model proved useful for pharmacologic deductions; all compounds caused a dose‐dependent inhibition of capsaicin‐induced pain and flare responses, with a rank order potency of AZ11760788 > AZ12048189 ≫ AZ12099548. In addition, the dose–response data showed that the minimal antagonist concentrations needed to inhibit TRPV1 was ≥6–7 times the equilibrium dissociation constant for each compound.

Conclusion

With careful design of a pharmacodynamic translational human pain model, it was possible to rank order TRPV1 efficacy among three investigational TRPV1 antagonists, and to estimate human efficacious concentrations.

Significance

This fast and cost‐effective translational approach allows for generation of human target engagement information early in drug development. This could be of value for other development programmes where pharmacological targets are expressed in peripheral sensory nerves.
The timing of oceanic anoxic events in the Cretaceous succession of Cauvery Basin: Constraints from 40Ar/39Ar ages of glauconite in the Karai Shale Formation
Authors: Bansal Udita , Pande Kanchan , Banerjee Santanu , Nagendra Raghavendramurthy , Jagadeesan Koyyodan Cheria
Published: March 2018

This study presents 40Ar/39Ar ages of autochthonous glauconites from the lower segment of the onshore Karai Shale Formation of the Cauvery Basin that constrain its age from 100.3 ± 0.7 to 92.6 ± 0.6 Ma. The 40Ar/39Ar plateau ages of the 3 glauconite samples are consistent with the existing biostratigraphic age of Late Albian to Middle Turonian of the Karai Shale Formation. These ages are significant because of the occurrences of oceanic anoxic event (OAE)1d and oceanic anoxic event (OAE)2 in contemporaneous offshore deposits, the Sattapadi Shale and Bhuvanagiri Formation, respectively. Although in the onshore deposits, the glauconite ages mark condensed deposits of the transgressive Karai Shale. As onshore glauconitic deposits may be transitional to organic‐rich black shale deposits offshore in modern and ancient sedimentary settings, the 40Ar/39Ar ages precisely constrains the timing of Cretaceous oceanic anoxic events reported in the Cauvery Basin.