bluuebunny/crossref_metadata_2025 huggingface dataset:
Small‐scale sea ice deformation during N‐ICE2015: From compact pack ice to marginal ice zone
Authors: Oikkonen Annu , Haapala Jari , Lensu Mikko , Karvonen Juha , Itkin Polona
Published: May 2017

We studied small‐scale (50 m to 5 km) sea ice deformation from ship radar images recorded during the N‐ICE2015 campaign. The campaign consisted of four consecutive drifting ice stations (Floes 1–4) north of Svalbard, with a total duration of nearly 5 months. Deformation was calculated using 5 different time intervals from 10 min to 24 h, and the deformation rate was found to depend strongly on the time scale. Floes 1–3 had a mean deformation rate within the range of 0.06–0.07 h−1 with the interval of 10 min, and 0.03–0.04 h−1 with the interval of 1 h. Floe 4 represented marginal ice zone (MIZ) with very high deformation rate, 0.14/0.08 h−1 with the interval of 10 min/1 h. Deep in the ice pack, high deformation rates occurred only with high wind and drift speed, while in MIZ they were found also during calm conditions. The deformation rates were found to follow power law scaling with respect to length and time scale even on this small scale and in small domain (15 km × 15 km). The length scale dependence of deformation rate depends on the time scale: the power law scaling exponent β of the whole study period decreases from 0.82 to 0.52 with the time interval increasing from 10 min to 24 h. Ship radar images reveal the importance of the deformation history of the ice pack, since the deformation events were initialized along the lines of previous damages.
A computational study on the nature of meso‐β scale vortex coalescence in a tropical atmosphere
Authors: Schecter David A.
Published: May 2017

Tropical weather systems commonly contain a variety of mesoscale vortices whose interactions may influence the timing of tropical cyclone formation. Previous computational studies have found that interactions ending in coalescence can either help or hinder development depending on the specific circumstances. Despite the potential importance of mesoscale vortex merger, complications introduced by baroclinic effects and diabatic processes have impeded progress toward elucidating its mechanics. The present study is an effort to advance current understanding by way of idealized numerical experiments with a cloud‐permitting model. Direct comparisons are made between dry adiabatic and moist diabatic simulations of meso‐β (20–200 km) scale vortex merger on a tropical oceanic f‐plane. Consistent with a number of earlier studies, deep cumulus convection is found to accelerate the late stage of surface‐concentrated vortex merger over a warm ocean. On the other hand, incorporating artificial radiation and cloud processes into the numerical model substantially hinders the merger of middle‐tropospheric vortices over a moderately cooler ocean. Such hindering coincides with the partial suppression of shear‐induced vortex misalignments whose amplifications and rotations appear to be essential to the dry adiabatic merger mechanism. The aforementioned dry merger mechanism is examined in detail. Irrotational winds linked to the horizontal divergence field are found to largely control the system‐centric influx of absolute vorticity, in sharp contrast to ideal two‐dimensional hydrodynamics. The consequences of lowering (raising) the sea‐surface temperature under the moist surface‐concentrated (middle‐tropospheric) system are briefly addressed.
Martian mesospheric cloud observations by IUVS on MAVEN: Thermal tides coupled to the upper atmosphere
Authors: Stevens M. H. , Siskind D. E. , Evans J. S. , Jain S. K. , Schneider N. M. , Deighan J. , Stewart A. I. F. , Crismani M. , Stiepen A. , Chaffin M. S. , McClintock W. E. , Holsclaw G. M. , Lefèvre F. , Lo D. Y. , Clarke J. T. , Montmessin F. , Jakosky B. M.
Published: May 2017

We report observations of Martian mesospheric ice clouds and thermospheric scale heights by the Imaging Ultraviolet Spectrograph on NASA's Mars Atmosphere and Volatile Evolution mission. The clouds are observed between 6 A.M. and 8 A.M. local time using mid‐UV limb observations between 60 and 80 km tangent altitude where ice particles that scatter sunlight can appear as detached layers near the equator. The equatorial longitudinal distribution shows populations of clouds near −110°E and −10°E as well as a population near 90°E, which does not have a clear precedent. The cloud populations indicate a wave 3 pattern near 70 km, which is confirmed by independent mesospheric temperature observations. Scale heights 100 km above the clouds derived from concurrent Imaging Ultraviolet Spectrograph (IUVS) observations also reveal a wave 3 longitudinal structure, suggesting that the temperature oscillations enabling the formation of mesospheric clouds couple to the upper atmosphere.
The shallow magma chamber of Stromboli Volcano (Italy)
Authors: Patanè D. , Barberi G. , De Gori P. , Cocina O. , Zuccarello L. , Garcia‐Yeguas A. , Castellano M. , D'Alessandro A. , Sgroi T.
Published: May 2017

In this work, we integrate artificial and natural seismic sources data to obtain high‐resolution images of the shallow inner structure of Stromboli Volcano. Overall, we used a total of 21,953 P readings from an active seismic experiment and an additional 2731 P and 992 S readings deriving from 269 local events. The well‐defined Vp, Vs, and Vp/Vs tomograms have highlighted the following: (i) the region where magma cumulates at shallow depths (2–4 km below sea level (bsl)), forming an elongated NE‐SW high‐velocity body (Vp ≥ 6.0 km/s and Vs ≥ 3.5 km/s), with a very fast velocity core (6.5 ≤ Vp < 7.0 km/s) of ~2 km3; (ii) the presence of some near‐vertical pipe‐like structures, characterized by relatively high P velocities values, mainly linked to past activity (e.g., Strombolicchio); and (iii) a near‐vertical pipe‐like volume with high Vp/Vs (1.78 ÷ 1.85), located beneath to the craters (down to ~1.0 km bsl), overlying a deeper region (1.0 to 3.0 km bsl) with low Vp/Vs (1.64 ÷ 1.69), interpreted as the actual and preferential pathway of magma toward the surface. Our results demonstrate the importance of combining passive and active seismic data to improve, in a tomographic inversion, the resolution of the volcanic structures and to discover where magma may be stored.
Initiation of positive streamer corona in low thundercloud fields
Authors: Cai Qiheng , Jánský Jaroslav , Pasko Victor P.
Published: May 2017

Formation of filamentary gas discharge forms, commonly referred to as streamers, is one of the conditions required for initiation and subsequent propagation of lightning leaders. It is quantitatively demonstrated that streamers can be initiated under thunderstorm conditions when two precipitation particles cause an enhancement of the electric field by passing in close vicinity of each other. Conditions for avalanche‐to‐streamer transition are documented using a model of two spherical hydrometeor particles placed in uniform ambient field. The results are presented in scaled form using similarity relations for gas discharges and can be applied for a wide range of thunderstorm conditions, including different air pressures, electric fields, and particle dimensions.
Anomalously large complete stress drop during the 2016 Mw 5.2 Borrego Springs earthquake inferred by waveform modeling and near‐source aftershock deficit
Authors: Ross Z. E. , Kanamori H. , Hauksson E.
Published: May 2017

The 2016 Mw 5.2 Borrego Springs earthquake occurred in the trifurcation area of the San Jacinto Fault Zone and generated more than 23,000 aftershocks. We analyze source properties of this earthquake along with 12,487 precisely located aftershock hypocenters to obtain an unusually detailed view of the rupture process and energy budget for this moderate earthquake. Source time functions are obtained using an empirical Green's function approach and are inverted for a slip distribution on the fault plane. The rupture propagated unilaterally to the northwest over a distance of 1.8 km, resulting in clear directivity signals. Two asperities are identified and the maximum slip is 2.54 m, resulting in a static stress drop of 78.2 MPa. Over 97% of the aftershocks occur more than 1 rupture length from the slip area. We conclude that the Borrego Springs earthquake had a complete stress drop and estimate the seismic efficiency to be 15–26%.
Parallel electron heating in the magnetospheric inflow region
Authors: Wang Shan , Chen Li‐Jen , Hesse Michael , Wilson Lynn B. , Bessho Naoki , Gershman Daniel J. , Ergun Robert E. , Phan Tai D. , Burch James L. , Dorelli John C. , Giles Barbara , Torbert Roy B. , Pollock Craig J. , Russell Christopher T. , Strangeway Robert , Avanov Levon , Lavraud Benoit , Moore Thomas E.
Published: May 2017

We analyzed 20 reconnection events observed by the Magnetosphere MultiScale mission, finding that in a subregion of the magnetospheric inflow, the electron temperature parallel to the magnetic field (Te||) decreases toward the separatrix with increasing densities. Such Te|| variation is not consistent with the heating through the parallel potential mechanism for magnetospheric electrons. Associated with the change in Te||, low‐energy gyrotropic magnetosheath‐like electrons are observed. These electrons may come from the magnetosheath, penetrate to the magnetospheric side possibly due to waves in the lower hybrid frequency range, and do not experience as much energization as those from deeper in the magnetosphere. In addition, as Te|| decreases, the high‐energy field‐aligned phase‐space densities decrease or fluctuate significantly over time. Wave‐particle interaction might produce energy conversion and cause the high‐energy phase‐space density variations.
Antenna structures and cloud‐to‐ground lightning location: 1995–2015
Authors: Kingfield Darrel M. , Calhoun Kristin M. , de Beurs Kirsten M.
Published: May 2017

Spatial analyses of cloud‐to‐ground (CG) lightning occurrence due to a rapid expansion in the number of antenna towers across the United States are explored by gridding 20 years of National Lightning Detection Network data at 500 m spatial resolution. The 99.8% of grid cells with ≥100 CGs were within 1 km of an antenna tower registered with the Federal Communications Commission. Tower height is positively correlated with CG occurrence; towers taller than 400 m above ground level experience a median increase of 150% in CG lightning density compared to a region 2 km to 5 km away. In the northern Great Plains, the cumulative CG lightning density near the tower was around 138% (117%) higher than a region 2 to 5 km away in the September–February (March–August) months. Higher CG frequencies typically also occur in the first full year following new tower construction, creating new lightning hot spots.
Systematic fluctuations in the global seismic moment release
Authors: Zaliapin Ilya , Kreemer Corné
Published: May 2017

We revisit the significance of the increased number of great earthquakes since December 2004. An analysis of the global seismic moment release during 1918–2014 inferred from the International Seismological Centre catalog rejects a null hypothesis of independence between earthquake seismic moments and occurrence times. Our results suggest the existence of temporal variation in the seismic moment distribution on a global scale with decreased moment release during 1975–2004 and a transition to a regime with increased moment release during the 1960s and after December 2004. We use complementary likelihood and regression analyses based on nonparametric resampling and parametric Monte Carlo simulations to construct tests powerful enough to reject the null hypothesis of independence.
Estimation of the differential stress from the stress rotation angle in low permeable rock
Authors: Ziegler Moritz O. , Heidbach Oliver , Zang Arno , Martínez‐Garzón Patricia , Bohnhoff Marco
Published: May 2017

Rotations of the principal stress axes are observed as a result of fluid injection into reservoirs. We use a generic, fully coupled 3‐D thermo‐hydro‐mechanical model to investigate systematically the dependence of this stress rotation on different reservoir properties and injection scenarios. We find that permeability, injection rate, and initial differential stress are the key factors, while other reservoir properties only play a negligible role. In particular, we find that thermal effects do not significantly contribute to stress rotations. For reservoir types with usual differential stress and reservoir treatment the occurrence of significant stress rotations is limited to reservoirs with a permeability of less than approximately 10−12 m2. Higher permeability effectively prevents stress rotations to occur. Thus, according to these general findings, the observed principal stress axes rotation can be used as a proxy of the initial differential stress provided that rock permeability and fluid injection rate are known a priori.
Spectral properties and associated plasma energization by magnetosonic waves in the Earth's magnetosphere: Particle‐in‐cell simulations
Authors: Sun Jicheng , Gao Xinliang , Lu Quanming , Chen Lunjin , Liu Xu , Wang Xueyi , Tao Xin , Wang Shui
Published: May 2017

In this paper, we perform a 1‐D particle‐in‐cell (PIC) simulation model consisting of three species, cold electrons, cold ions, and energetic ion ring, to investigate spectral structures of magnetosonic waves excited by ring distribution protons in the Earth's magnetosphere, and dynamics of charged particles during the excitation of magnetosonic waves. As the wave normal angle decreases, the spectral range of excited magnetosonic waves becomes broader with upper frequency limit extending beyond the lower hybrid resonant frequency, and the discrete spectra tends to merge into a continuous one. This dependence on wave normal angle is consistent with the linear theory. The effects of magnetosonic waves on the background cold plasma populations also vary with wave normal angle. For exactly perpendicular magnetosonic waves (parallel wave number k|| = 0), there is no energization in the parallel direction for both background cold protons and electrons due to the negligible fluctuating electric field component in the parallel direction. In contrast, the perpendicular energization of background plasmas is rather significant, where cold protons follow unmagnetized motion while cold electrons follow drift motion due to wave electric fields. For magnetosonic waves with a finite k||, there exists a nonnegligible parallel fluctuating electric field, leading to a significant and rapid energization in the parallel direction for cold electrons. These cold electrons can also be efficiently energized in the perpendicular direction due to the interaction with the magnetosonic wave fields in the perpendicular direction. However, cold protons can be only heated in the perpendicular direction, which is likely caused by the higher‐order resonances with magnetosonic waves. The potential impacts of magnetosonic waves on the energization of the background cold plasmas in the Earth's inner magnetosphere are also discussed in this paper.
Evaluation of anthropogenic influences on the Luhuitou fringing reef via spatial and temporal analyses (from isotopic values)
Authors: Cao D. , Cao W. , Yu K. , Wu G. , Yang J. , Su X. , Wang F.
Published: May 2017

Coral reefs have suffered remarkable declines worldwide. Nutrient overenrichment is considered to be one of the primary local causes. The Luhuitou fringing reef in southern China is a well‐known tourist destination that is subject to enormous coastal renovation. The mean δ13C, δ15N value, and carbon over nitrogen ratio (C/N) of particulate organic matter were −21.56 ± 1.94‰, 7.04 ± 3.81‰, and 5.81 ± 1.86, respectively, suggesting mixed sources of carbon and nitrogen. The IsoError calculations suggested that marine phytoplankton and marine benthic algae dominated the majority of carbon sources, while anthropogenic and terrestrial organic nitrogen dominated the nitrogen sources. A tendency toward greater terrestrial detritus and anthropogenic‐derived discharges was found during dry seasons and greater marine‐derived organic matter during wet seasons. These results demonstrated the existence of anthropogenic influences and high dissolved inorganic nitrogen concentrations and C/N ratios. Anthropogenic nutrient discharge moderated nitrogen limitation, whereas phosphorus became more important to the reef ecosystem. Despite the marine carbon sources dominated, freshwater and terrestrial‐derived organic carbon sources were also very important. Meanwhile, anthropogenic and terrestrial organic nitrogen sources were dominant. Therefore, pollution from more extensive region and anthropogenic activities from riverine sewage discharges adjacent to reefs should be focused to effectively reduce human‐derived nutrients on reefs.
Immunodeficiency: Secondary
Authors: Bright Philip , Richter Alex
Published: May 2017

Secondary immunodeficiency (SID) refers to an acquired immunodeficiency secondary to an extrinsic cause (e.g. disease, treatment) and can occur when any condition or treatment causes a reduction in number or function of immune components. Opportunistic or particularly severe infections should raise the suspicion of SID. SID is relatively common, and worldwide the most prevalent causes include malnutrition and advancing age. The aetiologies of SID can be loosely grouped into those caused by the related abnormalities of general health, underlying disease, barrier integrity or iatrogenic influences. Issues with general health that result in SID include malnutrition, advancing age, smoking and alcohol. Underlying diseases that cause SID include haematological malignancies, splenectomy/hyposplenism and some infections (e.g. human immunodeficiency virus (HIV)). Many diverse injuries, treatments or diseases can reduce barrier integrity resulting in SID, as well as a wide range of iatrogenic interventions. The treatment of SID depends on both the presentation and aetiology.

Key Concepts

Secondary immunodeficiency refers to an acquired immunodeficiency secondary to an extrinsic cause.

The aetiology of secondary immunodeficiency is often multifactorial and may present with diverse opportunistic infections.

Secondary immunodeficiency is common, and the most common aetiology worldwide is malnutrition.

Causes of secondary immunodeficiency can be loosely defined by aetiology into disorders of general health, barrier integrity, relating to underlying diseases or as iatrogenic.

Severe presentations of common infections and certain characteristic opportunistic infections should raise the suspicion of secondary immunodeficiency.

Many secondary immunodeficiencies relate to the use of medications, particularly the new generation of biological agents.

Infections, as well as being a result of immunodeficiency, may also cause secondary immunodeficiency.

The treatment of secondary immunodeficiency is complicated and dependent on both the presentation and the aetiology of the immunodeficiency.
Insurance and Genetic Information
Authors: Bombard Yvonne , King Wong Eugene , Lemmens Trudo
Published: May 2017

Advances in genomic technology have expanded the number of tests for which individuals can obtain additional risk estimates about their susceptibilities to disease. Genomic information that predicts disease risk is relevant to insurers because the amount that policyholders pay for insurance coverage is determined by assessing their level of disease risk. Without access to genomic information, insurers are concerned that individuals may purchase more insurance at unadjusted premiums, leading to adverse selection. However, not all genomic information is useful from an insurance viewpoint, and the complexity of interpreting genetic variants, coupled with the possibility of incidental findings, raises ethical issues with using applicants' genomic testing results. Moreover, some people are reluctant to undergo genetic testing or participate in genomic research because of the fear that they may have difficulty in obtaining insurance after disclosing their genomic results to insurers. As genomic testing becomes more prevalent, there are concerns that sections of the population will be denied insurance because of their genetic profile. The question of what governments should do about this is one that has been debated in many countries.

Key Concepts

Insurers request genetic test results from applicants to enable them to make an accurate assessment of their health risks in the underwriting process. However, patients and the public fear that they may have difficulty in obtaining insurance after disclosing their genomic results to insurers.

Not all genetic tests are useful for insurance underwriting; this will depend on the clinical validity and utility of the test, the nature and penetrance of the disease and the availability of treatment or management strategies.

Use of genomic data for insurance underwriting also raises ethical concerns due to the complexity of interpreting genomic variants and the possibility of discovering incidental findings from genomic data.

The public's fear of genetic discrimination by insurers appears to have consequences for public health and genetic research programme initiatives.

Moratoria or legislation to prohibit the use of genetic test results by insurers has been adopted by many countries to prevent insurance discrimination.

However, other ways to regulate the use of genetic tests in insurance include human rights or privacy‐based approaches.
Molecular Genetics of Penile Cancer
Authors: McCormick Barrett , Baumgarten Adam , Spiess Philippe E
Published: May 2017

Penile cancer is a rare malignancy in the United States and Europe but has a much higher prevalence in certain geographical areas including South America and Africa. Compared with other urological malignancies, there remains a paucity of information regarding the molecular mechanisms involved in penile cancer carcinogenesis. It is generally understood that there are two separate molecular pathways that contribute to carcinogenesis, one of which is largely related to human papillomavirus (HPV) infection. The second mechanism is much less clearly understood and is related to a combination of factors including those influenced by environmental effects and somatic or epigenetic changes. However, there also remains an element of interplay between the two mechanisms that adds to the complexity of understanding the disease. The aim of this review is to outline the current understanding of the genetic factors, current research and future directions involved in understanding the disease.

Key Concepts

Penile cancer is a rare entity and the mechanisms behind its carcinogenesis are not completely understood.

It is generally understood that the pathogenesis of penile cancer may related to both HPV mediated and non-mediated mechanisms.

The ability of the human papillomavirus to lead to malignancy is dependent on breakdown of normal cell degradation mechanisms as well as cell cycle alterations leading to uninhibited cell proliferation.

Non‐HPV mediated pathogenesis has numerous potential mechanisms and remains an ongoing area of study.

Continued focus on centers of excellence as well as international collaborations will be needed to continue to develop a full understanding of the disease.
Mechanisms of Chromosome Translocations in Cancer
Authors: Nickoloff Jac A
Published: May 2017

Chromosome translocations have long been known to be causative events in cancer. First observed as recurrent translocations in lymphomas and leukaemias, translocations are also found in solid tumours. One of the key hallmarks of cancer is genome instability, and chromosome translocations represent a critical form of genome instability that reflects mis‐repair of DNA double‐strand breaks (DSBs). DSBs are repaired by two main pathways, non‐homologous end joining and homologous recombination, and chromosome translocations can be created by both of these pathways. Many translocations associated with specific cancers are recurrent, reflecting selective pressure for inactivated tumour suppressor genes or activated oncogenes, which are early drivers of cancer phenotypes. Cancer therapeutics, including DNA reactive chemicals, topoisomerase inhibitors and radiation, are effective cancer treatments, but they can induce translocation‐mediated secondary malignancies at significant frequencies. Reducing the risk of these sequelae is an important goal in cancer research.

Key Concepts

Chromosome translocations are critical genomic rearrangements that are frequently found in lymphoid and solid tumours and other diseases.

Translocations arise when DNA double‐strand breaks arise simultaneously on two separate chromosomes and are mis‐rejoined.

Translocations observed in cancer may inactivate tumour suppressor genes or activate oncogenes by gene fusion or juxtaposition of a strong promoter with a proto‐oncogene.

Translocations are formed primarily through alternative non‐homologous end joining, but other double‐strand break repair mechanisms can contribute to translocation spectra, including classical non‐homologous end joining, homologous recombination and single‐strand annealing.

Cancer therapeutics may cause translocations that generate secondary, therapy‐induced cancers.

Translocation efficiency and junction positions are regulated by many factors including programmed DNA double‐strand breaks, spontaneous and induced DNA damage, DNA repair pathways, structural elements in DNA sequences such as repeated sequences and palindromes, relative locations chromosomes within nuclei and epigenetic factors.
A novel design of a Phase III trial of isradipine in early Parkinson disease (STEADY‐PD III)
Authors: Biglan Kevin M. , Oakes David , Lang Anthony E. , Hauser Robert A. , Hodgeman Karen , Greco Brittany , Lowell Jillian , Rockhill Rebecca , Shoulson Ira , Venuto Charles , Young Diony , Simuni Tanya ,   the Parkinson Study Group STEADY‐PD III Investigators
Published: May 2017

Objective

To describe the rationale for a novel study design and baseline characteristics of a disease‐modifying trial of isradipine 10 mg daily in early Parkinson disease (PD).

Methods

STEADY‐PDIII is a 36‐month, Phase 3, parallel group, placebo‐controlled study of the efficacy of isradipine 10 mg daily in 336 participants with early PD as measured by the change in the Unified Parkinson Disease Rating Scale (UPDRS) Part I‐III score in the practically defined ON state. Secondary outcome measures include clinically meaningful measures of disability progression in early PD: (1) Time to initiation and utilization of dopaminergic therapy; (2) Time to onset of motor complications; (3) Change in nonmotor disability. Exploratory measures include global measures of functional disability, quality of life, change in the ambulatory capacity, cognitive function, and pharmacokinetic analysis. Rationale for the current design and alternative design approaches are discussed.

Results

The entire cohort of 336 participants was enrolled at 55 Parkinson Study Group sites in North America. The percentage of male participants were 68.5% with a mean age of 61.9 years (sd 9.0), mean Hoehn and Yahr stage of 1.7 (sd 0.5), mean UPDRS total of 23.1 (sd 8.6), and MoCA of 28.1 (sd 1.4).

Interpretation

STEADY‐PD III has a novel and innovative design allowing for the determination of longer duration benefits on clinically relevant outcomes in a relatively small cohort on top of the benefit derived from symptomatic therapy. Baseline characteristics are similar to those in previously enrolled de novo PD trials. This study represents a unique opportunity to evaluate the potential impact of a novel therapy to slow progression of PD disability and provide clinically meaningful benefits.
Noise covariance matrices in state‐space models: A survey and comparison of estimation methods—Part I
Authors: Duník Jindřich , Straka Ondřej , Kost Oliver , Havlík Jindřich
Published: May 2017

This paper deals with the estimation of the noise covariance matrices of systems described by state‐space models. Stress is laid on the systematic survey and classification of both the recursive and batch processing methods proposed in the literature with a special focus on the correlation methods. Besides the correlation methods, representatives of other groups are introduced also with respect to their basic idea, estimate properties, assumptions and possible extensions, and user‐defined parameters. Common and dual properties of the methods are highlighted, and a simulation comparison using exemplary MATLAB implementations of the methods is provided.
Highly Efficient Virus Rejection with Self‐Organized Membranes Based on a Crosslinked Bicontinuous Cubic Liquid Crystal
Authors: Marets Nicolas , Kuo Daniel , Torrey Jason R. , Sakamoto Takeshi , Henmi Masahiro , Katayama Hiroyuki , Kato Takashi
Published: May 2017

To remove viruses from water, the use of self‐assembling liquid crystals is presented as a novel method for the synthesis of membranes with a regular pore size (below 1 nm) and controlled pore structures. Nanostructured bicontinuous cubic liquid‐crystalline (LC) thin films are photopolymerized onto a polysulfone support layer. It is found that these membranes reject the virus, Qβ bacteriophage (≈20 nm diameter) by >99.9999%. Prepressurization of the membrane appears to enhance their virus rejection properties. This is the first example of nanostructured LC membranes that are used for virus rejection, for which they show great potential.
Materials Nanoarchitecturing via Cation‐Mediated Protein Assembly: Making Limpet Teeth without Mineral
Authors: Ukmar‐Godec Tina , Bertinetti Luca , Dunlop John W. C. , Godec Aljaž , Grabiger Michal A. , Masic Admir , Nguyen Huynh , Zlotnikov Igor , Zaslansky Paul , Faivre Damien
Published: May 2017

Teeth are designed to deliver high forces while withstanding the generated stresses. Aside from isolated mineral‐free exception (e.g., marine polychaetes and squids), minerals are thought to be indispensable for tooth‐hardening and durability. Here, the unmineralized teeth of the giant keyhole limpet (Megathura crenulata) are shown to attain a stiffness, which is twofold higher than any known organic biogenic structures. In these teeth, protein and chitin fibers establish a stiff compact outer shell enclosing a less compact core. The stiffness and its gradients emerge from a concerted interaction across multiple length‐scales: packing of hydrophobic proteins and folding into secondary structures mediated by Ca2+ and Mg2+ together with a strong spatial control in the local fiber orientation. These results integrating nanoindentation, acoustic microscopy, and finite‐element modeling for probing the tooth's mechanical properties, spatially resolved small‐ and wide‐angle X‐ray scattering for probing the material ordering on the micrometer scale, and energy‐dispersive X‐ray scattering combined with confocal Raman microscopy to study structural features on the molecular scale, reveal a nanocomposite structure hierarchically assembled to form a versatile damage‐tolerant protein‐based tooth, with a stiffness similar to mineralized mammalian bone, but without any mineral.
Tailoring Auxetic and Contractile Graphene to Achieve Interface Structures with Fully Mechanically Controllable Thermal Transports
Authors: Gao Yuan , Yang Weizhu , Xu Baoxing
Published: May 2017

Graphene is considered as an ideal material candidate for next‐generation electronic devices due to its high carrier mobility while the associated thermal management has become a critical barrier. Designing graphene whose thermal transport properties can be tuned through external fields is highly desired. Here, an auxetic graphene (AG) and a contractile graphene (CG) are created and a conceptual design of thermal controllable graphene heterostructures is demonstrated by tailoring them together. Using computational simulations, it is shown that the thermal conductivity of graphene heterostructures can be regulated by patterning AG and CG unit cells with different interface properties under a uniaxial tensile strain. Analyses of both mechanical deformation and vibrational spectra indicate that the thermal transport properties of graphene heterostructures are highly dependent on their mechanical stress distribution, and also rely on the interfaces that are parallel with the directions of mechanical loadings. Theoretical models that integrate the contributions of mechanical loading and patterned‐interfaces are developed to quantitatively describe the thermal conductivity of graphene heterostructures. Good agreement of thermal conductivity between theoretical predictions and extensive simulations is obtained. These designs and findings are expected to pave a new route to seek interface‐mediated stretchable thermal electronics with mechanically controllable performance.
Catalytic Asymmetric 1,2‐Difunctionalization of Indolenines with α‐(Benzothiazol‐2‐ylsulfonyl) Carbonyl Compounds
Authors: Shao You‐Dong , Cheng Dao‐Juan
Published: May 2017

A novel catalytic asymmetric 1,2‐difunctionalization reaction of indolenines with α‐(benzothiazol‐2‐ylsulfonyl) carbonyl compounds was developed. By employing the strategy of Brønsted acid‐assisted chiral phosphoric acid catalysis, the Mannich addition/Smiles rearrangement cascade occurred smoothly and provided a new family of optically active 1,2‐difunctionalized 2‐substituted indolines in good yields and enantioselectivities.

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Mutagenesis‐Independent Stabilization of Class B Flavin Monooxygenases in Operation
Authors: Goncalves Leticia C. P. , Kracher Daniel , Milker Sofia , Fink Michael J. , Rudroff Florian , Ludwig Roland , Bommarius Andreas S. , Mihovilovic Marko D.
Published: May 2017

This paper describes the stabilization of flavin‐dependent monooxygenases under reaction conditions, using an engineered formulation of additives (the natural cofactors NADPH and FAD, and superoxide dismutase and catalase as catalytic antioxidants). This way, a 103‐ to 104‐fold increase of the half‐life was reached without resource‐intensive directed evolution or structure‐dependent protein engineering methods. The stabilized enzymes are highly valued for their synthetic potential in biotechnology and medicinal chemistry (enantioselective sulfur, nitrogen and Baeyer–Villiger oxidations; oxidative human metabolism), but widespread application was so far hindered by their notorious fragility. Our technology immediately enables their use, does not require structural knowledge of the biocatalyst, and creates a strong basis for the targeted development of improved variants by mutagenesis.

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Scanning Kelvin Probe Microscopy Reveals Planar Defects Are Sources of Electronic Disorder in Organic Semiconductor Crystals
Authors: Wu Yanfei , Ren Xinglong , McGarry Kathryn A. , Bruzek Matthew J. , Douglas Christopher J. , Frisbie C. Daniel
Published: May 2017

Electronic disorder in organic semiconductor single crystals, manifested as parallel surface potential domains with potential variations ranging from tens to hundreds of mV, is observed by scanning Kelvin probe microscopy. Chemical etching and X‐ray diffraction indicate that the potential domains are correlated with planar defects such as stacking faults. The results have important implications for understanding structure–transport relationships in organic semiconductor single crystals.
Ultrasmall Nanoplatelets: The Ultimate Tuning of Optoelectronic Properties
Authors: Zhou Yufeng , Celikin Mert , Camellini Andrea , Sirigu Gianluca , Tong Xin , Jin Lei , Basu Kaustubh , Tong Xin , Barba David , Ma Dongling , Sun Shuhui , Vidal François , Zavelani‐Rossi Margherita , Wang Zhiming M. , Zhao Haiguang , Vomiero Alberto , Rosei Federico
Published: May 2017

2D semiconducting nanoplatelets (NPLs) are an emerging class of photoactive materials. They can be used as building blocks in optoelectronic devices thanks to their large absorption coefficient, high carrier mobility, and unique thickness‐dependent optical transitions. The main drawback of NPLs is their large lateral size, which results in unfavorable band energy levels and low quantum yield (QY). Here, ultrasmall lead chalcogenide PbSe1–xSx NPLs are prepared, which exhibit an unprecedented QY of ≈60%, the highest ever reported for this structure. The NPLs are applied as light absorber in a photoelectrochemical system, leading to a saturated photocurrent density of ≈5.0 mA cm−2 (44 mL cm−2 d−1), which is a record for NPL‐based photoelectrodes in solar‐driven hydrogen generation. Ultrasmall NPLs hold the potential for breakthrough developments in the field of optically active nanomaterials.
Freestanding Flexible Li2S Paper Electrode with High Mass and Capacity Loading for High‐Energy Li–S Batteries
Authors: Yu Mingliang , Wang Zhiyu , Wang Yuwei , Dong Yanfeng , Qiu Jieshan
Published: May 2017

Lithium–sulfur (Li–S) batteries are a very appealing power source with extremely high energy density. But the use of a metallic‐Li anode causes serious safety hazards, such as short‐circuiting and explosion of the cells. Replacing a sulfur cathode with a fully‐lithiated lithium sulfide (Li2S) to pair with metallic‐Li‐free high‐capacity anodes paves a feasible way to address this issue. However, the practical utility of Li2S cathodes faces the challenges of poor conductivity, sluggish activation process, and high sensitivity to moisture and oxygen that make electrode production more difficult than dealing with sulfur cathodes. Here, an efficient but low‐cost strategy for easy production of freestanding flexible Li2S‐based paper electrodes with very high mass and capacity loading in terms of in situ carbonthermal reduction of Li2SO4 by electrospinning carbon is reported. This chemistry enables high loading but strong affinity of ultrafine Li2S nanoparticles in a freestanding conductive carbon‐nanofiber network, meanwhile greatly reducing the manufacturing complexity and cost of Li2S cathodes. Benefiting from enhanced structural stability and reaction kinetics, the areal specific capacities of such cathodes can be significantly boosted with less sacrificing of high‐rate and cycling capability. This unique Li2S‐cathode design can be directly applied for constructing metallic‐Li‐free or flexible Li–S batteries with high‐energy density.
Cellulose‐based Supercapacitors: Material and Performance Considerations
Authors: Wang Zhaohui , Tammela Petter , Strømme Maria , Nyholm Leif
Published: May 2017

One of the biggest challenges we will face over the next few decades is finding a way to power the future while maintaining strong socioeconomic growth and a clean environment. A transition from the use of fossil fuels to renewable energy sources is expected. Cellulose, the most abundant natural biopolymer on earth, is a unique, sustainable, functional material with exciting properties: it is low‐cost and has hierarchical fibrous structures, a high surface area, thermal stability, hydrophilicity, biocompatibility, and mechanical flexibility, which makes it ideal for use in sustainable, flexible energy storage devices. This review focuses on energy storage applications involving different forms of cellulose (i.e., cellulose microfibers, nanocellulose fibers, and cellulose nanocrystals) in supercapacitors, with particular emphasis on new trends and performance considerations relevant to these fields. Recent advances and approaches to obtaining high capacity devices are evaluated and the limitations of cellulose‐based systems are discussed. For the first time, a combination of device‐specific factors such as electrode structures, mass loadings, areal capacities, and volumetric properties are taken into account, so as to evaluate and compare the energy storage performance and to better assess the merits of cellulose‐based materials with respect to real applications.
Incidence, puberty, and fertility in 45,X/47,XXX mosaicism: Report of a patient and a literature review
Authors: Lim Han Hyuk , Kil Hong Ryang , Koo Sun Hoe
Published: May 2017

Turner syndrome (TS), characterized by short stature and premature ovarian failure, is caused by chromosomal aberrations with total or partial loss of one of the two X chromosomes. Spontaneous puberty, menarche, and pregnancy occur in some patients depending on the abnormality of the X. Moreover, spontaneous pregnancy is uncommon (<0.5%) for TS with 45,X monosomy. Among TS patients, 45,X/47,XXX karyotype is extremely rare. Previous reports have demonstrated that TS with 45,X/47,XXX is less severe than common TS due to higher occurrence of puberty (83%), menarche (57–67%), and fertility (14%) and lower occurrence of congenital anomalies (<5%). However, TS mosaicism may not reduce the frequency of short stature. We diagnosed a 10‐year‐girl with TS with 45,X/47,XXX mosaicism who presented with short stature. She showed mild TS phenotype including short stature but had spontaneous puberty. Based on our case and previous reports, we expect that girls with 45,X/47,XXX mosaicism may progress through puberty normally, without estrogen therapy. Therefore, it is necessary to consider specific guidelines for clinical decisions surrounding pubertal development and fertility in TS with 45,X/47,XXX karyotype.
Efficient Access to the Functionalized Bicyclic Pharmacophore of Spirolide C by Using a Selective Diels–Alder Reaction
Authors: Tsuchikawa Hiroshi , Minamino Kou , Hayashi Sho , Murata Michio
Published: May 2017

A functionalized bicyclic lactam that was used as a key intermediate in an efficient synthesis of the pharmacophore of potent marine toxin spirolide C was synthesized by using a highly selective Diels–Alder reaction. To improve the reactivity of this transformation without loss of selectivity, substrates that contained a silyl ether or silatrane moiety were elaborately designed and converted into the spirobicyclic core structure with stereochemical control over the two asymmetric centers at the C7 and C29 positions. Moreover, a further C−C bond formation by using a Hiyama cross‐coupling reaction of the vinyl silatrane derivative facilitated versatile modification at the C5 position with an aryl or alkenyl substituent.
Computed tomographic perfusion to Predict Response to Recanalization in ischemic stroke
Authors: Lansberg Maarten G. , Christensen Soren , Kemp Stephanie , Mlynash Michael , Mishra Nishant , Federau Christian , Tsai Jenny P. , Kim Sun , Nogueria Raul G. , Jovin Tudor , Devlin Thomas G. , Akhtar Naveed , Yavagal Dileep R. , Haussen Diogo , Dehkharghani Seena , Bammer Roland , Straka Matus , Zaharchuk Greg , Marks Michael P. , Albers Gregory W. ,   for the CT Perfusion to Predict Response to Recanalization in Ischemic Stroke Project (CRISP) Investigators
Published: May 2017

Objective

To assess the utility of computed tomographic (CT) perfusion for selection of patients for endovascular therapy up to 18 hours after symptom onset.

Methods

We conducted a multicenter cohort study of consecutive acute stroke patients scheduled to undergo endovascular therapy within 90 minutes after a baseline CT perfusion. Patients were classified as “target mismatch” if they had a small ischemic core and a large penumbra on their baseline CT perfusion. Reperfusion was defined as >50% reduction in critical hypoperfusion between the baseline CT perfusion and the 36‐hour follow‐up magnetic resonance imaging.

Results

Of the 201 patients enrolled, 190 patients with an adequate baseline CT perfusion study who underwent angiography were included (mean age = 66 years, median NIH Stroke Scale [NIHSS] = 16, median time from symptom onset to endovascular therapy = 5.2 hours). Rate of reperfusion was 89%. In patients with target mismatch (n = 131), reperfusion was associated with higher odds of favorable clinical response, defined as an improvement of ≥8 points on the NIHSS (83% vs 44%; p = 0.002, adjusted odds ratio [OR] = 6.6, 95% confidence interval [CI] = 2.1–20.9). This association did not differ between patients treated within 6 hours (OR = 6.4, 95% CI = 1.5–27.8) and those treated > 6 hours after symptom onset (OR = 13.7, 95% CI = 1.4–140).

Interpretation

The robust association between endovascular reperfusion and good outcome among patients with the CT perfusion target mismatch profile treated up to 18 hours after symptom onset supports a randomized trial of endovascular therapy in this patient population. Ann Neurol 2017;81:849–856
A Near‐Infrared Dye That Undergoes Multiple Interconversions through Acid–Base Equilibrium and Reversible Redox Processes
Authors: Asai Kengo , Fukazawa Aiko , Yamaguchi Shigehiro
Published: May 2017

A near‐infrared (NIR) polymethine dye (1), consisting of a cyclohepta[1,2‐b;4,3‐b′]dithiophene and two phenol moieties, was synthesized. This dye exhibited pH‐responsive changes in its photophysical properties due to a two‐step acid–base equilibrium that produced a protonated cation (1H+) and an anion (1−). While 1H+ showed an intense fluorescence in the red region of the visible spectrum, 1− exhibited a strong absorption in the NIR region. The tropylium ion character in 1H+ induces high pKa1 and pKa2 values for 1. Moreover, a stable radical (1.) was prepared, which showed a NIR absorption band with a maximum at circa 1600 nm. The cyclic voltammogram of 1. revealed a two‐step reversible redox process that produced 1− and the cation 1+, which is different from 1H+. These redox processes accompany drastic electrochromic changes in the vis–NIR region. Overall, 1 is susceptible to multiple interconversions between five forms, due to the multifaceted character of the cycloheptadithiophene skeleton.
In‐Cell Dual Drug Synthesis by Cancer‐Targeting Palladium Catalysts
Authors: Clavadetscher Jessica , Indrigo Eugenio , Chankeshwara Sunay V. , Lilienkampf Annamaria , Bradley Mark
Published: May 2017

Transition metals have been successfully applied to catalyze non‐natural chemical transformations within living cells, with the highly efficient labeling of subcellular components and the activation of prodrugs. In vivo applications, however, have been scarce, with a need for the specific cellular targeting of the active transition metals. Here, we show the design and application of cancer‐targeting palladium catalysts, with their specific uptake in brain cancer (glioblastoma) cells, while maintaining their catalytic activity. In these cells, for the first time, two different anticancer agents were synthesized simultaneously intracellularly, by two totally different mechanisms (in situ synthesis and decaging), enhancing the therapeutic effect of the drugs. Tumor specificity of the catalysts together with their ability to perform simultaneous multiple bioorthogonal transformations will empower the application of in vivo transition metals for drug activation strategies.
Ligand‐Enabled Auxiliary‐Free meta‐C−H Arylation of Phenylacetic Acids
Authors: Li Gen‐Cheng , Wang Peng , Farmer Marcus E. , Yu Jin‐Quan
Published: May 2017

The meta‐C−H arylation of free phenylacetic acid was realized using 2‐carbomethoxynorbornene (NBE‐CO2Me) as a transient mediator. Both the modified norbornene and the mono‐protected 3‐amino‐2‐hydroxypyridine type ligand are crucial for this auxiliary‐free meta‐C−H arylation reaction. A series of phenylacetic acids, including mandelic acid and phenylglycine, react smoothly with various aryl iodides to provide the meta‐arylated products in high yields.
An Orbital‐Overlap Complement to Atomic Partial Charge
Authors: Mehmood Arshad , Janesko Benjamin G.
Published: May 2017

Atomic partial charges are widely used to predict reactivity. Partial charge alone is often insufficient: the carbons of benzene and cyclobutadiene, or those of diamond, graphene, and C60, possess nearly identical partial charges and very different reactivities. Our atomic overlap distance complements computed partial charges by measuring the size of orbital lobes that best overlap with the wavefunction around an atom. Compact, chemically stable atoms tend to have overlap distances smaller than chemically soft, unstable atoms. We show here how combining atomic charges and overlap distances captures trends in aromaticity, nucleophilicity, allotrope stability, and substituent effects. Applications to recent experiments in organic chemistry (counterintuitive Lewis base stabilization of alkenyl anions in anionic cyclization) and nanomaterials chemistry (facile doping of the central atom in Au7 hexagons) illustrate this combination's predictive power.