bluuebunny/crossref_metadata_2025 huggingface dataset:
Improvements in a fast potentiometric seawater alkalinity determination
Authors: F Pérez F , F Ríos A , Rellán T , Álvarez M
Published: August 2017

In the present paper, we introduce some methodological improvements in a potentiometric technique for determining seawater alkalinity. This fast method (about two minutes per sample) uses open flasks and an ordinary titration system without thermostatic bath. A new potassium hydrogen phthalate-borax 4.4 buffer is proposed to calibrate the electrode near the end point of the titration. The pH values of this new buffer at different pH-scales and temperatures were determined using spectrophotometry. The combined use of this easy and improved two end-point method for alkalinity determination and certified reference material enables the alkalinity to be determined with an accuracy lower than 1µmolkg–1(0.05%).
Taphonomic processes in recent thanatocenoses at playa el pelícano, baja california
Authors: Avila-Serrano G , Téllez-Duarte MA
Published: August 2017

The northeastern coast of Baja California (Mexico) has extensive surface mollusk-shell deposits in exposed, semiprotected or protected sandy beaches. Waves, tides, currents and sediment transport influence the shell concentrations in the intertidal zone and control the morphology of these beaches. In order to evaluate the taphonomic processes involved in the formation of shell deposits in an exposed beach, we studied temporal changes in thanatocenoses of bivalves along 200 m of beach at spring tides in March, May and November 1993, and March and November 1994. Species were identified and their size, orientation (concave-up vs concave-down) and azimuth orientation of the anterior-posterior axis were measured. The assemblage was dominated by Glycymeris gigantea and included 15 common species. The shells showed a variable azimuth orientation, but with a trend parallel to the coastline, predominance of downward concavity and a polymodal size distribution with modes in 1 and 3 cm, in a size range of 0.3 to 8.5 cm. The taphonomic characteristics of these shell deposits may be useful in coastal paleoceanographic reconstructions.
Trophic spectrum of the california kingcroaker menticirrhus undulatus from ojo de liebre lagoon, baja california sur, mexico
Authors: Bocanegra-Castillo N , Abitia-Cárdenas LA , Galván-Magaña F
Published: August 2017

A total of 112 stomach contents of the California kingcroaker Menticirrhus undulatus from Ojo de Liebre Lagoon, Baja California Sur (Mexico), were analyzed. The samples were taken from January to November 1995. This species occurred all year round, with highest abundance in July. The index of relative importance indicated that M. undulatus consumed a total of 14 species, and the dominant prey were polychaetes of the genus Marphysa spp. (51.75%), the fish Ilypnus gilberti (31.84%) and mollusk remains (13.91%). According to Levin's index, M. undulatus is considered a specialist predator, with preference for benthic fauna.
Euphotic depth, irradiance attenuation and remote sensing k490 in bio-optical provinces of the gulf of california
Authors: Cervantes-Duarte R , Mueller JL , Trees CC , Maske H , Alvarez-Borrego S , Lara-Lara R
Published: August 2017

Algorithms are presented using remote sensing optical depth, 1/K490, to estimate the depth of the euphotic zone and depths where spectral irradiance at 490 nm are 10%, 3%, 1% and 0.3% of incident surface value. The linear empirical models are derived using data from radiometric profiles measured at various locations in the Gulf of California during cruises in 1995, 1997 and 1998. The models apply to three geographically and temporally separate bio-optical provinces of the gulf: the northern basin, the Midriff Islands and the southern basins. Relative uncertainties of the regression models for the 1% light depths for both spectral irradiance (490 nm) and EPAR range from approximately 5% in the northern basin to 10% in the southern basins.
Reproductive biology of Mithrax forceps (A. Milne-Edwards, 1875) (Crustacea: Decapoda: Majidae)
Authors: Hernández-Reyes IM , Palazón-Fernández JL , Bolaños-Curvelo JA , Hernández JE
Published: August 2017

Some aspects of the reproductive biology of Mithrax forceps were studied based on 580 specimens (380 males and 200 females) collected at Chacachacare, Margarita Island, Venezuela, from April 1984 to March 1985 and from July to November 1991. During the sampling period, males outnumbered females in the catch by almost two to one. Sex ratio was different from 1:1 in May, June, October, December, February and March. Male and female crabs attained sexual maturity at a size of 7.15 and 11.20 mm carapace length, respectively. Size at maturity for 50% of the population was 19.28 and 16.64 mm carapace length for males and females, respectively. As indicated by the presence of ovigerous females during the whole sampling period, the population can reproduce continuously during the year. Fecundity estimates of ovigerous females ranged from 34 to 4777 eggs (average = 1024 ± 93). Relative fecundity was 1.90 to 207.00 (average = 58.96 ± 4.54) eggs/mm carapace length, 1.82 to 200.29 (average = 56.32 ± 4.37) eggs/mm carapace width, and 12.19 to 1656.07 eggs/g (average = 465.16 ± 36.67). Fecundity was linear and positively related to carapace length and width, total weight and ovigerous mass weight. Embryonic development was divided into three stages according to the color of the ovigerous mass and the characteristics of the embryo.
Effect of the concentration of agar, alginate and carrageenan on the stability, toughness and nutrient leaching in artificial diets for abalone
Authors: Durazo-Béltran E , Viana MT
Published: August 2017

In order to evaluate the effect of different binders on the quality of artificial diets for abalone in terms of stability, nutrient leaching and toughness, three phycocolloids (agar, alginate and carrageenan) were used at different concentrations (0.5%, 1.0%, 1.5%, 2.0% and 2.5%), mixed with fish meal or abalone viscera silage as protein sources. Both stability and pellet toughness were influenced more by the protein source than by the type and concentration of the binder, as diets containing abalone viscera silage lost 20% dry matter, compared to the 10% lost in diets containing fish meal. However, nutrient leaching was not affected by the phycocolloid concentration. This result coincides with previous reports that leaching speed does not depend on stability. In general, all the binders used were effective at low concentrations (0.5%); therefore, the use of phycocolloids at low concentrations is recommended. Attention should also be given to the ingredients used, as these may have a greater influence on stability and toughness than the binders themselves.
Upper-ocean circulation patterns in the northern Gulf of California, expressed in Ers-2 Synthetic Aperture Radar Imagery
Authors: Martínez-Díaz-León A
Published: August 2017

ERS-2 Synthetic Aperture Radar (SAR) frames were collected over the northern Gulf of California during winter 1999. The frames, presented here as a single composite image (100 x 300 km), express a mesoscale meander or eddy-like feature, approximately 80 km wide, located close to the peninsula of Baja California. The eddy is expressed as bright, concentric bands that curve in an anticyclonic direction. The location and dimensions of the eddy are in very good agreement with the winter circulation of the northern Gulf of California described by Lavín et al. (1997), from the analysis of direct observations using satellite-tracked drifters and hydrographic surveys. The SAR image also depicts other smaller, cyclonic eddy-like features, located close to the mainland, which may be associated with the general circulation induced by the anticyclonic eddy. SAR images, together with the reduced number of in situ observations, can provide new and valuable information about the mesoscale circulation of the upper ocean in the Gulf of California, even when cloud cover prevents the use of other remote sensors, such as infrared radiometers and visible imaging systems.
Coseismic slip propagation on the Tohoku plate boundary fault facilitated by slip‐dependent weakening during slow fault slip
Authors: Ito Yoshihiro , Ikari Matt J. , Ujiie Kohtaro , Kopf Achim
Published: August 2017

Slow slip phenomena, including earthquake afterslip and discrete slow slip events (SSEs), may have a major effect on megathrust earthquakes in subduction zones; however, the nature of this effect is still incompletely understood. Here we report that in friction experiments using samples from the plate boundary fault zone in the 2011 Tohoku‐Oki earthquake, an increase in sliding velocity can induce a change from steady state frictional strength or slip‐strengthening friction to slip‐weakening frictional behavior. Specifically, significant slip weakening is caused by velocity steps with initial slip rates consistent with afterslip observed after the largest Tohoku earthquake foreshock on 9 March 2011. This suggests that the foreshock afterslip, which is slightly faster than discrete SSEs, is favorable for fault weakening that may have contributed to the large coseismic slip during the main shock on the shallow plate boundary fault during the Tohoku‐Oki earthquake.
Seismic estimates of turbulent diffusivity and evidence of nonlinear internal wave forcing by geometric resonance in the South China Sea
Authors: Fortin W. F. J. , Holbrook W. S. , Schmitt R. W.
Published: August 2017

The Luzon Passage generates some of the largest amplitude internal waves in the global ocean as the result of coupling between strong tides, strong stratification, and topography. These internal waves propagate into the South China Sea (SCS) and develop into soliton‐like internal wave pulses that are observed by moored instruments and satellite backscatter data. Despite the observation of these waves, little is known of the mechanisms related to their evolution into nonlinear wave pulses. Using seismic data, we find evidence that the geometry of bathymetric conditions between the Heng‐Chun and Lan‐Yu ridges drive nonlinear internal wave pulse generation. We produce three seismic images and associated maps of turbulent diffusivity to investigate structure around the two ridges and into the SCS. We do not observe large amplitude soliton‐like internal waves between the ridges, but do observe one outside the ridges, a finding in accord with the interpretation that wave pulses form due to geometrical resonance. Additionally, we find no evidence for lee wave activity above the ridges in either the seismic images or associated turbulence maps, suggesting an unlikelihood of hydraulic jump driven generation around the ridges. Our results show increased levels of turbulent diffusivity (1) in deep water below 1000 m, (2) associated with internal tide pulses, and (3) near the steep slopes of the Heng‐Chun and Lan‐Yu ridges as explored in this paper.
Three‐dimensional tidal flow in a fjord‐like basin with converging width: An analytical model
Authors: Ross Lauren , de Swart Huib , Ensing Erik , Valle‐Levinson Arnoldo
Published: August 2017

A three‐dimensional analytical model was used to understand tidal dynamics in deep and narrow (fjord‐like) basins. This model allows the width of the basin to decay exponentially with along‐channel distance from the mouth. Both the length scale of exponential convergence
and the friction parameter
(vertical eddy viscosity) were the free parameters. Model results show amplification of the tidal amplitude toward the head of the basin. Amplification depends on the narrowing rate of the funnel‐like width of the channel and on friction. Cross‐channel variations in along‐channel tidal flow are also sensitive to the friction parameter. A typical along‐channel tidal flow distribution was found across the channel when the vertical eddy viscosity was characteristic of a basin with strong friction, or the Stokes number was larger than 0.1 (St > 0.1). Maximum along‐channel tidal velocities (ranging from 0.25 to 0.5 m s−1 depending on width convergence strength) were located in the center of the basin and at the surface. Decreasing values of the Stokes number, St < 0.1, resulted in along‐channel velocity maxima located near the lateral boundaries and subsurface in the middle of the channel. These tidal flow distributions were explained by a critical value of St and were verified with observations from Reloncavi Fjord, Chilean Patagonia yielding good agreement.
Mechanisms underlying recent decadal changes in subpolar North Atlantic Ocean heat content
Authors: Piecuch Christopher G. , Ponte Rui M. , Little Christopher M. , Buckley Martha W. , Fukumori Ichiro
Published: August 2017

The subpolar North Atlantic (SPNA) is subject to strong decadal variability, with implications for surface climate and its predictability. In 2004–2005, SPNA decadal upper ocean and sea‐surface temperature trends reversed from warming during 1994–2004 to cooling over 2005–2015. This recent decadal trend reversal in SPNA ocean heat content (OHC) is studied using a physically consistent, observationally constrained global ocean state estimate covering 1992–2015. The estimate's physical consistency facilitates quantitative causal attribution of ocean variations. Closed heat budget diagnostics reveal that the SPNA OHC trend reversal is the result of heat advection by midlatitude ocean circulation. Kinematic decompositions reveal that changes in the deep and intermediate vertical overturning circulation cannot account for the trend reversal, but rather ocean heat transports by horizontal gyre circulations render the primary contributions. The shift in horizontal gyre advection reflects anomalous circulation acting on the mean temperature gradients. Maximum covariance analysis (MCA) reveals strong covariation between the anomalous horizontal gyre circulation and variations in the local wind stress curl, suggestive of a Sverdrup response. Results have implications for decadal predictability.
Seasonal fluctuations of ichthyoplankton assemblage in the northeastern South China Sea influenced by the Kuroshio intrusion
Authors: Huang Delian , Zhang Xia , Jiang Zhijian , Zhang Jingping , Arbi Iman , Jiang Xin , Huang Xiaoping , Zhang Wenjing
Published: August 2017

The distribution and assemblage of ichthyoplankton related to local hydrographic features, especially intrusion of the Kuroshio Current (KC) and Guangdong Coastal Current (GCC) in the northeastern South China Sea (NESCS) were investigated in this study. A total of 193 species of ichthyoplankton belonging to 141 genera and 66 families were recognized in summer 2015 and late‐winter 2016. The ichthyoplankton assemblage was identified with distinct seasonal differences, and the differences were responded well with the oceanography conditions. In summer, the assemblages were identified into offshore and inshore groups, as controlled by the South China Sea Warm Current (SCSWC) in off‐shelf, upwelling, and the diluted water from the Pearl River in inshore. In winter, three groups were divided, representing the southwestern inshore, intrusion of the KC in the eastern offshore, and the GCC in the northern inshore area, respectively. Furthermore, Sigmops gracilis and Vinciguerria sp.3 were probably brought into the NESCS by intrusion of the KC from the eastern Luzon Strait. In addition, high ichthyoplankton abundance was found in high chlorophyll a located in upwelling areas in the northern coastal area in summer and in the southwestern Taiwan Bank in winter, respectively. The nutrition outcropped by the upwelling together, and those brought from the Pearl River probably supported high food availability of the ichthyoplankton in the northern coast of the NESCS.
The influence of variable slope‐water characteristics on dissolved oxygen levels in the northern California Current System
Authors: Durski Scott M. , Barth John A. , McWilliams James C. , Frenzel Hartmut , Deutsch Curtis
Published: August 2017

Observations have suggested a trend of decreasing dissolved oxygen (DO) and increasing spiciness in summertime middepth slope waters and bottom shelf waters along the United States west coast over the past 50 years, but they have also demonstrated a large amount of interannual and decadal variability. Shelf bottom water and slope water properties can be influenced by both local and remote effects, including changes in circulation or changes in the characteristics of the source waters supplying the region. A regional‐scale, coupled physical biogeochemical model has been developed to simulate seasonal‐to‐decadal scale variability along the US west coast to discern the physical dynamics behind these spatial and temporal patterns. A simulation run from 1981 to 2006 with forcing that incorporates the larger scale interannual trends reproduces the development of low DO late in the upwelling season, the considerable interannual variability and the reported tendency toward a shoaling, more spicy, and oxygen‐depleted, northern California Undercurrent (CU). Whereas the trend in spiciness in the model results from increased influence of equatorial relative to subarctic source waters, the decreases in DO are found to additionally be a consequence of local biogeochemical processes. In order to better understand the interannual variability, years of the simulation were classified into four groups based on intensity of upwelling forcing and undercurrent strength. Slope water characteristics, shelf‐slope exchange, and slope‐basin exchange were compared across the four cases. Years with both strong upwelling and a strong undercurrent generated the most negative anomalies in slope‐water DO late in the upwelling season.
Distributed randomized model structure selection for NARX models
Authors: Avellina M. , Brankovic A. , Piroddi L.
Published: August 2017

Model structure selection (MSS) is a critical problem in the nonlinear identification field. In the framework of polynomial nonlinear autoregressive [moving average] models with exogenous input variables, it is formulated as the combinatorial problem of finding the subset of regressors that yields optimal model accuracy. Increasing the set of potential model terms improves the flexibility of the model but results in a computational overload and may even jeopardize the ability of the MSS algorithm to find the optimal model. In this work, a distributed optimization scheme is developed to tackle the MSS task for large‐sized candidate regressor sets. The regressor set is split among a group of independent processors, and each of them executes an MSS routine on its local subset. Then, the processors exchange information regarding the selected models, and the corresponding regressors are distributed among all the units for a new MSS round. The procedure is repeated until convergence of all processors to the same solution. Besides a drastic reduction in the computational time, thanks to the inherent parallelizability of the algorithm execution, the proposed distributed optimization scheme can also be beneficial in terms of model accuracy, due to a more efficient exploration of the search space.
Near‐Infrared Triggered Release of uPA from Nanospheres for Localized Hyperthermia‐Enhanced Thrombolysis
Authors: Wang Xiaolei , Wei Chaochao , Liu Mengke , Yang Ting , Zhou Weimin , Liu Ying , Hong Kui , Wang Shuhua , Xin Hongbo , Ding Xingwei
Published: August 2017

Currently, most thrombolytic agents are limited by short circulation time and excessive dose needed for clinical therapy, which increases lethal risk for intracranial hemorrhage. Here, a near‐infrared‐triggered, controlled‐release system, using gold@mesoporous silica core–shell nanospheres (Au@MSNs) with phase‐changed material 1‐tetradecanol, is formulated to release urokinase plasminogen activators (uPA) on demand. The prepared system presents a sensitive system for releasing uPA, owing to an elevated temperature created by Au@MSNs‐induced photothermal effect. For in vitro study, a 3D printed vein vasculature is designed and fabricated to simulate the thrombolysis of system in blood vessel. Murine tail thrombus model is also built to evaluate thrombolysis in vivo. Consequently, localized hyperthermia is validated to possess an effective enhancement for thrombolysis. Therefore, according to the results, the fabricated system demonstrates two aspects of potential superiority: controlled uPA release for reducing risk of side effects, and hyperthermia‐enhanced thrombolysis locally for decreasing drug dosage. Assisted with thermal thrombolysis, the present formulated system shows a high efficiency, on‐demand drug release, and thus a safer protocol for thrombolytic therapy, which fits the developing trends of precision medicine.
Metal‐Organic Frameworks Derived Nanotube of Nickel–Cobalt Bimetal Phosphides as Highly Efficient Electrocatalysts for Overall Water Splitting
Authors: Yan Liting , Cao Lei , Dai Pengcheng , Gu Xin , Liu Dandan , Li Liangjun , Wang Ying , Zhao Xuebo
Published: August 2017

The design of highly efficient, stable, and noble‐metal‐free bifunctional electrocatalysts for overall water splitting is critical but challenging. Herein, a facile and controllable synthesis strategy for nickel–cobalt bimetal phosphide nanotubes as highly efficient electrocatalysts for overall water splitting via low‐temperature phosphorization from a bimetallic metal‐organic framework (MOF‐74) precursor is reported. By optimizing the molar ratio of Co/Ni atoms in MOF‐74, a series of CoxNiyP catalysts are synthesized, and the obtained Co4Ni1P has a rare form of nanotubes that possess similar morphology to the MOF precursor and exhibit perfect dispersal of the active sites. The nanotubes show remarkable hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) catalytic performance in an alkaline electrolyte, affording a current density of 10 mA cm−2 at overpotentials of 129 mV for HER and 245 mV for OER, respectively. An electrolyzer with Co4Ni1P nanotubes as both the cathode and anode catalyst in alkaline solutions achieves a current density of 10 mA cm−2 at a voltage of 1.59 V, which is comparable to the integrated Pt/C and RuO2 counterparts and ranks among the best of the metal‐phosphide electrocatalysts reported to date.
Introduction of Nature's Complexity in Engineered Blood‐compatible Biomaterials
Authors: Ippel Bastiaan D. , Dankers Patricia Y. W.
Published: August 2017

Biomaterials with excellent blood‐compatibility are needed for applications in vascular replacement therapies, such as vascular grafts, heart valves and stents, and in extracorporeal devices such as hemodialysis machines and blood‐storage bags. The modification of materials that are being used for blood‐contacting devices has advanced from passive surface modifications to the design of more complex, smart biomaterials that respond to relevant stimuli from blood to counteract coagulation. Logically, the main source of inspiration for the design of new biomaterials has been the endogenous endothelium. Endothelial regulation of hemostasis is complex and involves a delicate interplay of structural components and feedback mechanisms. Thus, challenges to develop new strategies for blood‐compatible biomaterials now lie in incorporating true feedback controlled mechanisms that can regulate blood compatibility in a dynamic way. Here, supramolecular material systems are highlighted as they provide a promising platform to introduce dynamic reciprocity, due to their inherent dynamic nature.
Synthetic Biomaterials to Rival Nature's Complexity—a Path Forward with Combinatorics, High‐Throughput Discovery, and High‐Content Analysis
Authors: Zhang Douglas , Lee Junmin , Kilian Kristopher A.
Published: August 2017

Cells in tissue receive a host of soluble and insoluble signals in a context‐dependent fashion, where integration of these cues through a complex network of signal transduction cascades will define a particular outcome. Biomaterials scientists and engineers are tasked with designing materials that can at least partially recreate this complex signaling milieu towards new materials for biomedical applications. In this progress report, recent advances in high throughput techniques and high content imaging approaches that are facilitating the discovery of efficacious biomaterials are described. From microarrays of synthetic polymers, peptides and full‐length proteins, to designer cell culture systems that present multiple biophysical and biochemical cues in tandem, it is discussed how the integration of combinatorics with high content imaging and analysis is essential to extracting biologically meaningful information from large scale cellular screens to inform the design of next generation biomaterials.
Reprogrammable Phononic Metasurfaces
Authors: Bilal Osama R. , Foehr André , Daraio Chiara
Published: August 2017

Phononic metamaterials rely on the presence of resonances in a structured medium to control the propagation of elastic waves. Their response depends on the geometry of their fundamental building blocks. A major challenge in metamaterials design is the realization of basic building blocks that can be tuned dynamically. Here, a metamaterial plate is realized that can be dynamically tuned by harnessing geometric and magnetic nonlinearities in the individual unit cells. The proposed tuning mechanism allows a stiffness variability of the individual unit cells and can control the amplitude of transmitted excitation through the plate over three orders of magnitude. The concepts can be extended to metamaterials at different scales, and they can be applied in a broad range of engineering applications, from seismic shielding at low frequency to ultrasonic cloaking at higher frequency ranges.
Motion Manipulation of Micro‐ and Nanomotors
Authors: Tu Yingfeng , Peng Fei , Wilson Daniela A.
Published: August 2017

Inspired by the self‐migration of microorganisms in nature, artificial micro‐ and nanomotors can mimic this fantastic behavior by converting chemical fuel or external energy into mechanical motion. These self‐propelled micro‐ and nanomotors, designed either by top‐down or bottom‐up approaches, are able to achieve different applications, such as environmental remediation, sensing, cargo/sperm transportation, drug delivery, and even precision micro‐/nanosurgery. For these various applications, especially biomedical applications, regulating on‐demand the motion of micro‐ and nanomotors is quite essential. However, it remains a continuing challenge to increase the controllability over motors themselves. Here, we will discuss the recent advancements regarding the motion manipulation of micro‐ and nanomotors by different approaches.
Superior Photocatalytic H2 Production with Cocatalytic Co/Ni Species Anchored on Sulfide Semiconductor
Authors: Zhao Guixia , Sun Yubin , Zhou Wei , Wang Xiangke , Chang Kun , Liu Guigao , Liu Huimin , Kako Tetsuya , Ye Jinhua
Published: August 2017

Downsizing transition metal‐based cocatalysts on semiconductors to promote photocatalytic efficiency is important for research and industrial applications. This study presents a novel and facile strategy for anchoring well‐dispersed metal species on CdS surface through controlled decarboxylation of the ethylenediaminetetraacetate (EDTA) ligand in the metal–EDTA (M–EDTA) complex and CdS mixture precursor to function as a cocatalyst in the photocatalytic H2 evolution. Microstructure characterization and performance evaluation reveal that under visible light the resulting pentacoordinated Co(II) and hexacoordinated Ni(II) on CdS exhibits a high activity of 3.1 mmol h−1 (with turnover frequency (TOF) of 626 h−1 and apparent quantum efficiency (AQE) of 56.2% at 420 nm) and 4.3 mmol h−1 (with TOF of 864 h−1 and AQE of 67.5% at 420 nm), respectively, toward cocatalytic hydrogen evolution, and the cocatalytic activity of such a hexacoordinated Ni(II) even exceeds that of platinum. Further mechanistic study and theoretical modeling indicate that the fully utilized Co(II)/Ni(II) active sites, efficient charge transfer, and favorable kinetics guarantee the efficient activities. This work introduces a promising precursor, i.e., M–EDTA for planting well‐dispersed transition metal species on the sulfide supports by a facile wet‐chemistry approach, providing new opportunities for photocatalytic H2 production at the atomic/molecular scale.
Doxorubicin Adsorbed on Carbon Nanotubes: Helical Structure and New Release Trigger
Authors: Sadaf Shamaila , Walder Lorenz
Published: August 2017

The well‐known drug delivery system “doxorubicin physically loaded on carbon nanotubes” (Dox@CNT) is visualized by scanning tunneling microscopy at the molecular level, revealing rich architectural variability of Dox@CNT, and allowing to measure and rationalize reported loading efficiencies (80–200%) for the first time from image analysis. Reduction of Dox@CNT is identified as a so far unknown intrinsic release mechanism of biochemically relevance for Dox from Dox@CNT requiring no further CNT surface modification beside Dox loading. Electron injection into Dox@CNT from an electrode or from the biological reducing agent glutathione (GSH) leads to irreversible release of Dox. Its rate follows a linear free energy relationship (reduction potential vs log (Dox release rate)) with half‐life times from below seconds to hours. With extracellular GSH levels in the micromolar range and intracellular GSH concentrations of 10 × 10−3m or even higher, the findings can explain the preferential intracellular release of Dox from its physically adsorbed state on CNTs. The influence of acidity on the release rate of Dox on pristine 6,5‐CNTs in the absence of GSH is found to be negligible. The experimental findings are strongly supported by semi‐empirical calculations.
Van Der Waals Hybrid Perovskite of High Optical Quality by Chemical Vapor Deposition
Authors: Chen Zhizhong , Wang Yiping , Sun Xin , Guo Yuwei , Hu Yang , Wertz Esther , Wang Xi , Gao Hanwei , Lu Toh‐Ming , Shi Jian
Published: August 2017

2D hybrid perovksite (RNH3)2PbX4 materials not only serve as ideal platforms to study fundamental physics such as polariton dynamics but also show promise for optoelectronic and electro‐optic applications. However, for the preparation of high optical quality crystals, mechanical exfoliation has to be applied in the past. In this work, the vapor phase growth of single crystalline (C4H9NH3)2PbI4 flakes with high optical quality is reported. Individual single crystalline domains show lateral size about 5–10 µm with defined rectangular shape. Spectroscopic studies show room temperature photoluminescence full width at half maximum of 70 meV and decay lifetime of several nanoseconds, indicating comparably high quality with mechanically exfoliated counterparts. Exciton binding energy 279 ± 46 meV and electron–phonon coupling strength around 20 meV are revealed. This vacuum‐based method may provide a solution for integrating layered perovskites into optoelectronic devices and systems.
All‐Polymer Photonic Microcavities Doped with Perylene Bisimide J‐Aggregates
Authors: Lova Paola , Grande Vincenzo , Manfredi Giovanni , Patrini Maddalena , Herbst Stefanie , Würthner Frank , Comoretto Davide
Published: August 2017

Thanks to exciting chemical and optical features, perylene bisimide J‐aggregates are ideal candidates to be employed for high‐performance plastic photonic devices. However, they generally tend to form π–π stacked H‐aggregates that are unsuitable for implementation in polymer resonant cavities. In this work, the efficient compatibilization of a tailored perylene bisimide forming robust J‐aggregated supramolecular polymers into amorphous polypropylene is introduced. The new nanocomposite is then implemented into an all‐polymer planar microcavity, which provides strong and directional spectral redistribution of the J‐aggregate photoluminescence, due to a strong modification of the photonic states. A systematic analysis of the photoemitting processes, including photoluminescence decay and quantum yields, shows that the optical confinement in the polymeric microcavity does not introduce any additional nonradiative de‐excitation pathways to those already found in the J‐aggregate nanocomposite film and pave the way to PBI‐based high‐performance plastic photonic devices.
Maskless Fabrication of Aluminum Nanoparticles for Plasmonic Enhancement of Lead Halide Perovskite Lasers
Authors: Wang Shuai , Fang Jimao , Zhang Chen , Sun Shang , Wang Kaiyang , Xiao Shumin , Song Qinghai
Published: August 2017

Lead halide perovskite microlasers have been intensively studied in the past few years. While a number of unique laser properties have been demonstrated, the main laser characteristics are determined by the crystal quality and the shapes of synthesized materials. Patterning the semiconductors with plasmonic nanostructures is an effective way to control light emission and absorption. However, due to the instability of perovskites, most of nanofabrication technologies of plasmonic nanostructures will significantly spoil the qualities of perovskite devices. Here the surface plasmon enhanced laser emissions from all‐inorganic lead halide perovskites are experimentally demonstrated. Without using any mask or expensive pattern generations, relatively uniform aluminum nanoparticles (NPs) are deposited onto the top surface of CsPbBr3 perovskites with electron beam evaporation. After the deposition of optimized aluminum NPs, the thresholds of whispering‐gallery‐mode lasers in CsPbBr3 perovskite microrods are significantly reduced by more than 20% and the output intensities of perovskite microlasers are significantly enhanced by more than an order of magnitude via the plasmonic resonances. Considering the simple, controllable, and cost‐effective fabrication process, this research shall route a new avenue to the control of perovskite microlasers and their applications.
Phosphorescent Ionic Iridium(III) Complexes Displaying Counterion‐Dependent Emission Colors for Flexible Electrochromic Luminescence Device
Authors: Ma Yun , Yang Jin , Liu Shujuan , Xia Huiting , She Pengfei , Jiang Rui , Zhao Qiang
Published: August 2017

Stimulus‐responsive luminescent materials have drawn considerable interest because they are ideal candidates for optoelectronic applications. Herein, a series of phosphorescent iridium(III) complexes [(CZPY)2IrNH]+X− (X− = PF6−, I−, Br−, Cl−) containing two NH moieties in the N^N ligand is reported. These complexes exhibit significantly counterion‐dependent emission color change from green (493 nm) to orange (590 nm) in CH3CN. Besides, the emission color of [(CZPY)2IrNH]+PF6− is sensitive to the external electric field. Upon applying a voltage, the emission color of the complex in solution is changed evidently from orange to green at the cathode within several seconds. Moreover, with the advantages of high ionic conductivity, thermal stability, and mechanical strength, a bisimidazolium‐based polymeric ionic liquid is designed and synthesized as the electrolyte. Ultimately, a flexible electrochromic luminescence device is successfully fabricated, which exhibits excellent performance and properties, such as good flexibility, low operation voltage, fast response time, and good reversibility.
Nickel‐Catalyzed C−N Cross‐Coupling of Primary Imines with Subsequent In Situ [2+2] Cycloaddition or Alkylation
Authors: Power Dennis J. , Jones Kieran D. , Kampmann Sven S. , Flematti Gavin R. , Stewart Scott G.
Published: August 2017

Herein, we report a new method for the C−N cross‐coupling of primary imines by using an inexpensive air‐stable nickel catalyst. This procedure allows for a subsequent in situ reaction with moisture‐sensitive reagents. In this study, we also report secondary [2+2] cycloaddition and alkylation reactions. A diverse range of substrates were explored to highlight the usefulness of this combination of reactions. The reaction products from the cycloaddition pathway, through a Staudinger reaction, have potential applications as β‐lactam antibiotics.
Recognition‐then‐Reaction Enables Site‐Selective Bioconjugation to Proteins on Live‐Cell Surfaces
Authors: Cui Cheng , Zhang Hui , Wang Ruowen , Cansiz Sena , Pan Xiaoshu , Wan Shuo , Hou Weijia , Li Long , Chen Meiwan , Liu Yuan , Chen Xigao , Liu Qiaoling , Tan Weihong
Published: August 2017

Site‐selective protein modification is a key step in facilitating protein functionalization and manipulation. To accomplish this, genetically engineered proteins were previously required, but the procedure was laborious, complex, and technically challenging. Herein we report the development of aptamer‐based recognition‐then‐reaction to guide site‐selective protein/DNA conjugation in a single step with outstanding selectivity and efficiency. As models, several proteins, including human thrombin, PDGF‐BB, Avidin, and His‐tagged recombinant protein, were studied, and the results showed excellent selectivity under mild reaction conditions. Taking advantage of aptamers as recognition elements with extraordinary selectivity and affinity, this simple preparation method can tag a protein in a complex milieu. Thus, with the aptamer obtained from cell‐SELEX, real‐time modification of live‐cell membrane proteins can be achieved in one step without any pre‐treatment.
Tuning Crystallization Pathways through the Mesoscale Assembly of Biomacromolecular Nanocrystals
Authors: Tao Fei , Han Qian , Liu Kaiqiang , Yang Peng
Published: August 2017

Macromolecular crystallization has many implications in biological and materials science. Similar to the crystallization of other molecules, macromolecular crystallization conventionally considers a critical nucleus, followed by crystallographic packing of macromolecules to drive further crystal growth. Herein, we discover a distinctive macromolecular crystallization pathway by developing the concept of a macromolecular mesocrystal. This nonclassical polymer crystallization occurs through the mesoscale self‐assembly of (bio)macromolecular nanocrystals. The new concept for macromolecular crystallization presented herein is fundamental and relevant to many fields, including materials science, chemistry, biomimetics, nanoscience, and structural biology.
Radical Hydrodehalogenation of Aryl Bromides and Chlorides with Sodium Hydride and 1,4‐Dioxane
Authors: Hokamp Tobias , Dewanji Abhishek , Lübbesmeyer Maximilian , Mück‐Lichtenfeld Christian , Würthwein Ernst‐Ulrich , Studer Armido
Published: August 2017

A practical method for radical chain reduction of various aryl bromides and chlorides is introduced. The thermal process uses NaH and 1,4‐dioxane as reagents and 1,10‐phenanthroline as an initiator. Hydrodehalogenation can be combined with typical cyclization reactions, proving the nature of the radical mechanism. These chain reactions proceed by electron catalysis. DFT calculations and mechanistic studies support the suggested mechanism.
Release of Enzymatically Active Deubiquitinating Enzymes upon Reversible Capture by Disulfide Ubiquitin Reagents
Authors: de Jong Annemieke , Witting Katharina , Kooij Raymond , Flierman Dennis , Ovaa Huib
Published: August 2017

Deubiquitinating enzymes (DUBs) catalyze the cleavage of ubiquitin from target proteins. Ubiquitin is post‐translationally attached to proteins and serves as an important regulatory signal for key cellular processes. In this study, novel activity‐based probes to study DUBs were synthesized that comprise a ubiquitin moiety and a novel disulfide warhead at the C‐terminus. These reagents can bind DUBs covalently by forming a disulfide bridge between the active‐site cysteine residue and the ubiquitin‐based probe. As disulfide bridges can be broken by the addition of a reducing agent, these novel ubiquitin reagents can be used to capture and subsequently release catalytically active DUBs, whereas existing capturing agents bind irreversibly. These novel reagents allow for the study of these enzymes in their active state under various conditions.
Characterization of the RhI/dppe‐Catalyzed Ring Expansion of 2‐Alkyl‐Benzocyclobutenones by DFT Calculations
Authors: Qin Hua‐Li , Zhao Chuang , Leng Jing , Kantchev Eric Assen B.
Published: August 2017

The [(dppe)RhCl]‐catalysed ring expansion of 2‐methylbenzocyclobutenone has been proposed to occur by C−C oxidative addition to rhodaindanone, β‐hydride elimination, hydrorhodation and C−C reductive elimination. DFT calculations [IEFPCM(1,4‐dioxane, 383.15 K)/PBE0/DGDZVP level of theory] here confirm this mechanism. As proposed, oxidative addition into CHMe−CO bond is preferred over the alternative CHMe‐aryl insertion. The barriers of oxidative addition, β‐hydride elimination hydrorhodation, and reductive elimination are 23.6 (rate‐determining), 8.9, 10.4, and 13.1 kcal mol−1, respectively. Therefore, the β‐hydride elimination/hydrorhodation steps to/from an octahedral RhIII‐hydride serve as a fast equilibrating hydrogen shuffle flanking the two slower C−C bond breaking/making steps. This is consistent with the weak kinetic isotope effect observed experimentally when 2‐CH3 and 2‐CD3benzocyclobutenone react competitively in a 1:1 ratio. The reaction barriers calculated with more modern, dispersion interaction‐corrected methods (SMD/M06 and IEFPCM/ωB97xD) follow identical trends.
Discriminant diffusion maps based k‐nearest‐neighbour for batch process fault detection
Authors: Li Yuan , Liu Yadong , Zhang Cheng
Published: August 2017

In this paper, a novel discriminant diffusion maps based k‐nearest‐neighbour rule (DDM‐kNN) is developed for the high‐dimensional data of batch process and nonlinear characteristics of the data, and the traditional multivariate statistical process control and monitoring methods is less effective. Firstly, a discriminant kernel parameter is applied to the framework of the diffusion maps, and the Gaussian kernel width is selected from the within‐class width and the between‐class width according to discriminating sample class labels, which can make kernel function effectively extract data correlation features and exactly describe the structure characteristics of data original space in the low‐dimensional feature. Subsequently, the adapted kNN rule is applied to the low‐dimensional manifold feature space for fault detection. The effectiveness of DDM for the performance of data dimension reduction and feature extraction is verified in 3 arm spiral test data experiments compared with other dimensionality reduction methods, and successfully shows the high‐dimensional data in the low‐dimensional space and optimally preserves the original intrinsic nonlinear structure of the dataset. In addition, DDM‐kNN is applied to penicillin fermentation process monitoring and fault detection, and results also verify the effectiveness of the proposed method by integrating discriminant diffusion maps with k‐nearest‐neighbour rule.
Effect of time to initiation of postoperative radiation therapy on survival in surgically managed head and neck cancer
Authors: Graboyes Evan M. , Garrett‐Mayer Elizabeth , Ellis Mark A. , Sharma Anand K. , Wahlquist Amy E. , Lentsch Eric J. , Nussenbaum Brian , Day Terry A.
Published: August 2017

BACKGROUND

The objective of this study was to determine the effects of National Comprehensive Cancer Network (NCCN) guideline–adherent initiation of postoperative radiation therapy (PORT) and different time‐to‐PORT intervals on the overall survival (OS) of patients with head and neck squamous cell carcinoma (HNSCC).

METHODS

The National Cancer Data Base was reviewed for the period of 2006‐2014, and patients with HNSCC undergoing surgery and PORT were identified. Kaplan‐Meier survival estimates, Cox regression analysis, and propensity score matching were used to determine the effects of initiating PORT within 6 weeks of surgery and different time‐to‐PORT intervals on survival.

RESULTS

This study included 41,291 patients. After adjustments for covariates, starting PORT >6 weeks postoperatively was associated with decreased OS (adjusted hazard ratio [aHR], 1.13; 99% confidence interval [CI], 1.08‐1.19). This finding remained in the propensity score–matched subset (hazard ratio, 1.21; 99% CI, 1.15‐1.28). In comparison with starting PORT 5 to 6 weeks postoperatively, initiating PORT earlier was not associated with improved survival (aHR for ≤ 4 weeks, 0.93; 99% CI, 0.85‐1.02; aHR for 4‐5 weeks, 0.92; 99% CI, 0.84‐1.01). Increasing durations of delay beyond 7 weeks were associated with small, progressive survival decrements (aHR, 1.09, 1.10, and 1.12 for 7‐8, 8‐10, and >10 weeks, respectively).

CONCLUSIONS

Nonadherence to NCCN guidelines for initiating PORT within 6 weeks of surgery was associated with decreased survival. There was no survival benefit to initiating PORT earlier within the recommended 6‐week timeframe. Increasing durations of delay beyond 7 weeks were associated with small, progressive survival decrements. Cancer 2017;123:4841‐50. © 2017 American Cancer Society.
Inhibiting heat shock protein 90 and the ubiquitin‐proteasome pathway impairs metabolic homeostasis and leads to cell death in human pancreatic cancer cells
Authors: Belalcazar Astrid , Shaib Walid L. , Farren Matthew R. , Zhang Chao , Chen Zhengjia , Yang Lily , Lesinski Gregory B. , El‐Rayes Bassel F. , Nagaraju Ganji Purnachandra
Published: August 2017

BACKGROUND

Heat shock protein 90 (HSP90) and the ubiquitin‐proteasome pathway play crucial roles in the homeostasis of pancreatic cancer cells. This study combined for the first time the HSP90 inhibitor ganetespib (Gan) and the proteasome inhibitor carfilzomib (Carf) to target key mechanisms of homeostasis in pancreatic cancer. It was hypothesized that Gan plus Carf would elicit potent antitumor activity by modulating complementary homeostatic processes.

METHODS

In vitro and in vivo effects of this combination on mechanisms of cell growth and viability were evaluated with human pancreatic cancer cell lines (MIA PaCa‐2 and HPAC).

RESULTS

Combined treatment with Gan and Carf significantly decreased cell viability. The mechanism varied by cell line and involved G2‐M cell‐cycle arrest accompanied by a consistent reduction in key cell‐cycle regulatory proteins and concomitant upregulation of p27. Further studies revealed increased autophagy markers, including the upregulation of autophagy related 7 and light chain 3 cleavage, and evidence of apoptosis (increased Bax expression and processing of caspase 3). Immunoblot analyses confirmed the modulation of other pathways that influence cell viability, including phosphoinositide 3‐kinase/Akt and nuclear factor κB. Finally, the treatment of athymic mice bearing HPAC tumors with Gan and Carf significantly reduced tumor growth in vivo. An immunoblot analysis of freshly isolated tumors from animals at the end of the study confirmed in vivo modulation of key signaling pathways.

CONCLUSIONS

The results reveal Gan plus Carf to be a promising combination with synergistic antiproliferative, apoptotic, and pro‐autophagy effects in preclinical studies of pancreatic cancer and will further the exploration of the utility of this treatment combination in clinical trials. Cancer 2017;123:4924‐33. © 2017 American Cancer Society.