bluuebunny/crossref_metadata_2025 huggingface dataset:
What drives computation chemistry forward: theory or computing power?
Authors: Ng Wenfa
Published: January 2018

History is often thought to be dull and boring – where large numbers of facts are memorized for passing exams. But the past informs the present and future, especially in delineating the context surrounding specific events that, in turn, help provide a deeper understanding of their underlying causes and implications. Scientific progress (whether incremental or breakthroughs) is built upon prior work. Chronological examination of the field’s evolution reveals the existence of major “epochs” (e.g., transition from semi-empirical methods to first principles calculations), and the centrality of key ideas (e.g., Schrodinger equation and Born Oppenheimer approximation) in potentiating progress in the field. The longstanding question of whether computing power (both capacity and speed) or theoretical insights play a more important role in advancing computation chemistry was examined by taking into account the field’s development holistically. Specifically, availability of large amount of computing power at declining cost, and advent of graphics processing unit (GPU) powered parallel computing are enabling tools for solving up to now intractable problems. On the other hand, this essay argues (using Born Oppenheimer approximation as an example) that theoretical insights’ role in unlocking problems through simple (but insightful) assumptions is often overlooked. Collectively, the essay should be useful as a primer for appreciating major development periods in computation chemistry, from which counterfactual questions illuminate the relative importance of intuition and advances in computer science in moving the field forward.
Graphical illustration for explaining mass spectrum fingerprinting in microbial identification
Authors: Ng Wenfa
Published: January 2018

Pattern recognition is commonly used for identifying an unknown entity from a set of known objects curated in a database – and find use in various applications such as fingerprint matching and microbial identification. Whether matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) or electrospray ionization tandem mass spectrometry (ESI MS/MS), mass spectrometry is increasingly used in identifying microbes in the research and clinical settings via species- or strain-specific mass spectrum signatures. Although the existence of unique biomarkers - such as ribosomal proteins - underpins mass spectrometry-based microbial identification, absence of corresponding genome or proteome information in publicly accessible databases for a large fraction of extant microbes significantly hamper biomarker (and species) assignment. Nevertheless, the reproducible generation of species-specific mass spectrum across different growth and environmental conditions opens up the possibility of identifying unknown microbes via comparing peak positions between mass spectra, without biomarker identities. Thus, the mass spectrum fingerprinting (pattern recognition) approach circumvents the need for biomarker information, where alignment of as many mass peaks as possible (particularly, those of phylogenetic significance) between spectra is the basis for identification. In contrast, variation in gene expression and metabolism (and biomolecules’ abundances) with environmental and nutritional factors, meant that alignment of peak intensities, though desired, is not a strict requirement in species annotation. With large diversity of biomolecules present in each microbial species, mass spectrometry-based microbial identification is inherently data-intensive, which requires statistical tools and computers for implementing pattern recognition. Nevertheless, relegation of algorithmic details to the backend of software obfuscates the approach’s conceptual underpinnings and hinders students’ understanding. More important, mathematics-centric approaches for explaining the conceptual basis of pattern recognition, though useful, are generally less pedagogically accessible to students relative to visual illustration techniques. This short primer describes a simple graphical illustration (featuring three examples common in mass spectrometry-based biotyping workflows) that attempts to explain the conceptual underpinnings of mass spectrum fingerprinting, and highlights caveats for avoiding misidentifications.
Graphical illustration for explaining mass spectrum fingerprinting in microbial identification
Authors: Ng Wenfa
Published: January 2018

Pattern recognition is commonly used for identifying an unknown entity from a set of known objects curated in a database, and find use in various applications such as fingerprint matching and microbial identification. Mass spectrometry is increasingly used in identifying microbes in the research and clinical settings via species- or strain-specific mass spectrum signatures. Although the existence of unique biomarkers (such as ribosomal proteins) underpins mass spectrometry-based microbial identification, absence of corresponding genome or proteome information in public databases for a large fraction of extant microbes significantly hamper biomarker (and species) assignment. However, the reproducible generation of species-specific mass spectrum across different growth and environmental conditions opens up the possibility of identifying unknown microbes, without biomarker identities, via comparing peak positions between mass spectra. Thus, the mass spectrum fingerprinting (pattern recognition) approach circumvents the need for biomarker information, where alignment of as many mass peaks as possible (particularly, those of phylogenetic significance) between spectra is the basis for identification. In contrast, variation in gene expression and metabolism with environmental and nutritional factors, meant that alignment of peak intensities, though desired, is not a strict requirement in species annotation. With large diversity of biomolecules present in each microbial species, mass spectrometry-based microbial identification is inherently data-intensive, which necessitates statistical tools and computers for implementation. However, relegation of algorithmic details to the backend of software obfuscates the approach’s conceptual underpinnings and hinders understanding. More importantly, mathematics-centric approaches for explaining the conceptual basis of pattern recognition, though useful, are generally less pedagogically accessible to students relative to visual illustration techniques. This short primer describes a simple graphical illustration that explains the conceptual underpinnings of mass spectrum fingerprinting, and highlights caveats for avoiding misidentifications, and may find use as a supplement in a microbiology or bioinformatics course for introducing the conceptual basis of pattern recognition based microbial identification by mass spectrometric analysis.
Evidence of Ostrea lurida (Carpenter 1894) population structure in Puget Sound, WA
Authors: Heare J. Emerson , Blake Brady , Davis Jonathon P. , Vadopalas Brent , Roberts Steven B.
Published: January 2018

Where restoration efforts occur, such as with Ostrea lurida in Puget Sound, Washington, it is important to consider genetic population structure. Traits that hold adaptive advantage such as reproductive timing and stress resilience may differ at local scales. Using three established populations of O.lurida within Puget Sound Washington, we performed a reciprocal transplant experiment and monitored survival, growth, reproduction. We found that performance differed for each population at each of these three metrics. O.lurida from a relatively harsh home site environment with low primary production and high dynamic habitats exhibited generally greater survival at all sites, whereas those from a relatively lush home site environment with high primary production and lower habitat dynamics exhibited generally greater reproductive activity at all sites. Populations from sites with shorter growing seasons exhibited greater growth in sites with longer growing periods, suggesting a countergradient adaptation may have occurred in these populations.
Evidence of Ostrea lurida (Carpenter 1864) population structure in Puget Sound, WA
Authors: Heare J. Emerson , Blake Brady , Davis Jonathan P. , Vadopalas Brent , Roberts Steven B.
Published: January 2018

Where restoration efforts occur, such as with Ostrea lurida in Puget Sound, Washington, it is important to consider genetic population structure. Traits that hold adaptive advantage such as reproductive timing and stress resilience may differ at local scales. Using three established populations of O.lurida within Puget Sound Washington, we performed a reciprocal transplant experiment and monitored survival, growth, reproduction. We found that performance differed for each population at each of these three metrics. O.lurida from a relatively harsh home site environment with low primary production and high dynamic habitats exhibited generally greater survival at all sites, whereas those from a relatively lush home site environment with high primary production and lower habitat dynamics exhibited generally greater reproductive activity at all sites. Populations from sites with shorter growing seasons exhibited greater growth in sites with longer growing periods, suggesting a countergradient adaptation may have occurred in these populations.
The seasonal reproduction number of dengue fever impacts of climate on transmission
Authors: Polwiang Sittisede
Published: January 2018

Background: The dengue fever is a mosquito-borne viral disease and a regular epidemic in Thailand. The peak of the dengue epidemic period is around June to August during the rainy season. It is believed that the climate is an important factor for dengue transmission.Method: A mathematical model for vector-host infectious disease was used to calculate the impacts of climate to the transmission of dengue virus. In this study, the data of climate and dengue fever cases were derived from Chiang Mai during 2004-2014, Thailand. The value of seasonal reproduction number was calculated to evaluate the potential, severity and persistence of dengue infection.Results: The mosquito population was increasing exponentially from the start of the rainy season in early May and reached its the peak in late June. The simulations suggest that the greatest potential for the dengue transmission occurs when the temperature is 28.7ºC. The seasonal reproduction numbers were larger than one from late March to end of August and reaching the peak in June. The highest incidences occurred in August due to the delay of transmission humans-mosquito-humans. Increasing mean temperature by 1ºC, the number of incidences increases 30%. However, a very high or very low temperature reduces the number of infection.Discussion and Conclusion: The results show that the dengue infection depends on the seasonal variation of the climate. The rainfall provides places for the mosquitoes to lay eggs and develop to adult stage. The temperature plays an important role in the life cycle and behavior of the mosquitoes. A very high or very low temperature reduces the risk of the dengue infection.
Assessment of water pollution in the Brazilian Pampa biome by means of stress biomarkers in tadpoles of the leaf frog Phyllomedusa iheringii (Anura: Hylidae)
Authors: Santos Tiago G , Melo Roberto , Costa e Silva Dennis , Nunes Mauro , Franco Jeferson Franco, JL
Published: January 2018

The Brazilian Pampa biome is currently under constant threat due to increase of agriculture and improper management of urban effluents. Studies with focus on the assessment of impacts caused by human activities in this biome are scarce. In the present study we measured stress-related biomarkers in the muscle tissue of tadpoles of the leaf frog Phyllomedusa iheringii as a tool for the assessment of potential aquatic contamination in selected ponds (S1 and S2) nearby agricultural areas in comparison to a reference site. A significant decrease in acetylcholinesterase activity was observed in S2 when compared to S1 and reference. The levels of total-hydroperoxides were increased in S2 site. In parallel, increased activity of the antioxidant enzymes catalase, superoxide dismutase and glutathione S-transferase were observed in S2 when compared to S1 and reference. Based on the results, we drawn attention to the harmful effects caused by indiscriminate use of pesticides on the Pampa biome borders. Our study also validates Phyllomedusa iheringii as a valuable organism for field-based ecotoxicological studies. M
Assessment of water pollution in the Brazilian Pampa biome by means of stress biomarkers in tadpoles of the leaf frog Phyllomedusa iheringii (Anura: Hylidae)
Authors: Santos Tiago G , Melo Roberto , Costa e Silva Dennis , Nunes Mauro , Franco Jeferson Franco, JL
Published: January 2018

The Brazilian Pampa biome is currently under constant threat due to increase of agriculture and improper management of urban effluents. Studies with focus on the assessment of impacts caused by human activities in this biome are scarce. In the present study we measured stress-related biomarkers in tadpoles of the leaf frog Phyllomedusa iheringii, an endemic species to the Pampa biome, and tested its suitability as a bioindicator for the assessment of potential aquatic contamination in selected ponds (S1 and S2) nearby agricultural areas in comparison to a reference site. A significant decrease in acetylcholinesterase activity was observed in S2 when compared to S1 and reference. The levels of total-hydroperoxides were increased in S2 site. In parallel, increased activity of the antioxidant enzymes catalase, superoxide dismutase and glutathione S-transferase were observed in S2 when compared to S1 and reference. Further studies are necessary in order to correlate the changes observed here with different chemical stressors in water, as well as to elucidate mechanisms of toxicity induced by pesticides in amphibian species endemic to the Pampa biome. Nevertheless, our study validates Phyllomedusa iheringii as a valuable bioindicator in environmental studies.
Sequencing 16S rRNA gene fragments using the PacBio SMRT DNA sequencing system
Authors: Schloss Patrick D , Jenior Matthew L , Koumpouras Charles C. , Westcott Sarah L , Highlander Sarah K
Published: January 2018

Over the past 10 years, microbial ecologists have largely abandoned sequencing 16S rRNA genes by the Sanger sequencing method and have instead adopted highly parallelized sequencing platforms. These new platforms, such as 454 and Illumina's MiSeq, have allowed researchers to obtain millions of high quality, but short sequences. The result of the added sequencing depth has been significant improvements in experimental design. The tradeoff has been the decline in the number of full-length reference sequences that are deposited into databases. To overcome this problem, we tested the ability of the PacBio Single Molecule, Real-Time (SMRT) DNA sequencing platform to generate sequence reads from the 16S rRNA gene. We generated sequencing data from the V4, V3-V5, V1-V3, V1-V5, V1-V6, and V1-V9 variable regions from within the 16S rRNA gene using DNA from a synthetic mock community and natural samples collected from human feces, mouse feces, and soil. The mock community allowed us to assess the actual sequencing error rate and how that error rate changed when different curation methods were applied. We developed a simple method based on sequence characteristics and quality scores to reduce the observed error rate for the V1-V9 region from 0.69 to 0.027%. This error rate is comparable to what has been observed for the shorter reads generated by 454 and Illumina's MiSeq sequencing platforms. Although the per base sequencing cost is still significantly more than that of MiSeq, the prospect of supplementing reference databases with full-length sequences from organisms below the limit of detection from the Sanger approach is exciting.
Concept learning of ecological and artificial stimuli in rhesus macaques
Authors: Altschul Drew , Jensen Greg , Terrace Herbert S
Published: January 2018

The study of concepts in animals is complicated by the possibility that performance reflects reinforcement learning of discriminative cues, which might be used to categorize of stimuli. To minimize that possibility, we trained seven rhesus macaques to respond, in a specific order, to four simultaneously presented exemplars of different perceptual concepts. These exemplars were drawn at random from large banks of images; in some conditions, the stimuli changed on every trial. Subjects nevertheless identified and ordered these stimuli correctly. Three subjects learned to correctly order ecologically relevant concepts; four subjects, to order close-up sections of paintings by four artists with distinctive styles. All subjects classified stimuli significantly better than that predicted by chance, and outperformed a feature-based computer vision algorithm, even when the exemplars were changed on every trial. Furthermore, six subjects (three using ecological stimuli and three using paintings) transferred these concepts to novel stimuli. Our results suggest that monkeys possess a flexible ability to form class-based perceptual concepts that cannot be explained as the mere discrimination of physical features.
Perceptual category learning of photographic and painterly stimuli in rhesus macaques (Macaca mulatta) and humans
Authors: Altschul Drew , Jensen Greg , Terrace Herbert S
Published: January 2018

Humans are highly adept at categorizing visual stimuli, but studies of human categorization are typically validated by verbal reports. This makes it difficult to perform comparative studies of categorization using non-human animals. Interpretation of comparative studies is further complicated by the possibility that animal performance may merely reflect reinforcement learning, whereby discrete features act as discriminative cues for categorization. To assess and compare how humans and monkeys classified visual stimuli, we trained 7 rhesus macaques and 41 human volunteers to respond, in a specific order, to four simultaneously presented stimuli at a time, each belonging to a different perceptual category. These exemplars were drawn at random from large banks of images, such that the stimuli presented changed on every trial. Subjects nevertheless identified and ordered these changing stimuli correctly. Three monkeys learned to order naturalistic photographs; four others, close-up sections of paintings with distinctive styles. Humans learned to order both types of stimuli. All subjects classified stimuli at levels substantially greater than that predicted by chance or by feature-driven learning alone, even when stimuli changed one every trial. However, humans more closely resembled monkeys when classifying the more abstract painting stimuli than the photographic stimuli. This points to a common classification strategy in both species, on which humans can rely on in the absence of linguistic labels for categories.
Engagement as predictors of performance in a single cohort of undergraduate chiropractic students
Authors: Rix Jacqueline , Dewhurst Philip , Cooke Caroline , Newell David
Published: January 2018

Objective:

To investigate the potential association of novel academic and nonacademic factors with chiropractic student academic performance.

Methods:

Students enrolled into year 1 of a chiropractic master's degree (MChiro) at our college were selected for this study. Data collected included demographics, attendance, virtual learning environment use, additional learning needs, previous degree qualifications, and summative marks. Differences between students who had to take an examination more than once (resit) and nonresit students were explored using t test and χ2 analysis. Relationships between attendance and end-of-year marks were explored using regression analysis.

Results:

Male students outperformed female students in four of the six units and as the total year average. Students who attended <80% of classes were more likely to have a resit in one or more units (relative risk [RR] = 2.6; 95% confidence interval [CI], 1.4–4.9). Students who performed poorly (<70%) in the semester 1 unit of a course on human structure and failed the semester 1 practical assessment of a course on clinical management were significantly more likely to have one or more resit assessments in semester 2 units (RR = 3.5 [95% CI, 2.2–5.7]; RR = 3.2 [95% CI, 2.0–4.9]). Attendance and unit 105 were independent predictors of one or more resits at the end-of-year (R2 = 0.86, p < .001).

Conclusion:

Attendance and first semester summative marks were associated with end-of-year performance. As such, these markers of performance may be used to flag struggling students in the program.
Radiocarbon Content of Dissolved Organic Carbon in the South Indian Ocean
Authors: Bercovici S. K. , McNichol A. P. , Xu L. , Hansell D. A.
Published: January 2018

We report four profiles of the radiocarbon content of dissolved organic carbon (DOC) spanning the South Indian Ocean (SIO), ranging from the Polar Front (56°S) to the subtropics (29°S). Surface waters held mean DOC Δ14C values of −426 ± 6‰ (~4,400 14C years) at the Polar Front and DOC Δ14C values of −252 ± 22‰ (~2,000 14C years) in the subtropics. At depth, Circumpolar Deep Waters held DOC Δ14C values of −491 ± 13‰ (~5,400 years), while values in Indian Deep Water were more depleted, holding DOC Δ14C values of −503 ± 8‰ (~5,600 14C years). High‐salinity North Atlantic Deep Water intruding into the deep SIO had a distinctly less depleted DOC Δ14C value of −481 ± 8‰ (~5,100 14C years). We use multiple linear regression to assess the dynamics of DOC Δ14C values in the deep Indian Ocean, finding that their distribution is characteristic of water masses in that region.
Quantifying Postfire Aeolian Sediment Transport Using Rare Earth Element Tracers
Authors: Dukes David , Gonzales Howell B. , Ravi Sujith , Grandstaff David E. , Van Pelt R. Scott , Li Junran , Wang Guan , Sankey Joel B.
Published: January 2018

Grasslands, which provide fundamental ecosystem services in many arid and semiarid regions of the world, are undergoing rapid increases in fire activity and are highly susceptible to postfire‐accelerated soil erosion by wind. A quantitative assessment of physical processes that integrates fire‐wind erosion feedbacks is therefore needed relative to vegetation change, soil biogeochemical cycling, air quality, and landscape evolution. We investigated the applicability of a novel tracer technique—the use of multiple rare earth elements (REE)—to quantify soil transport by wind and to identify sources and sinks of wind‐blown sediments in both burned and unburned shrub‐grass transition zone in the Chihuahuan Desert, NM, USA. Results indicate that the horizontal mass flux of wind‐borne sediment increased approximately threefold following the fire. The REE tracer analysis of wind‐borne sediments shows that the source of the horizontal mass flux in the unburned site was derived from bare microsites (88.5%), while in the burned site it was primarily sourced from shrub (42.3%) and bare (39.1%) microsites. Vegetated microsites which were predominantly sinks of aeolian sediments in the unburned areas became sediment sources following the fire. The burned areas showed a spatial homogenization of sediment tracers, highlighting a potential negative feedback on landscape heterogeneity induced by shrub encroachment into grasslands. Though fires are known to increase aeolian sediment transport, accompanying changes in the sources and sinks of wind‐borne sediments may influence biogeochemical cycling and land degradation dynamics. Furthermore, our experiment demonstrated that REEs can be used as reliable tracers for field‐scale aeolian studies.
Lateral Variations in Foreland Flexure of a Rifted Continental Margin: The Aquitaine Basin (SW France)
Authors: Angrand P. , Ford M. , Watts A. B.
Published: January 2018

Rift inheritance can play a key role in foreland basin geometry and behavior. If the foreland basin initiates soon after rifting, thermal cooling can also contribute significantly to subsidence. We investigate the effects of crustal inheritance (Aptian‐Cenomanian rifting) on the evolution of the Campanian to middle Miocene flexural Aquitaine foreland basin, northern Pyrenees, France. Surface and subsurface data define rifted crustal geometry and postrift thermal subsidence. Analysis of Bouguer gravity anomalies coupled with flexural modeling constrains the lateral variations of elastic thickness, plate flexure, and controlling loads. The Aquitaine foreland is divided along‐strike into three sectors. The relative role of surface and subsurface (i.e., buried) loading varies along‐strike, and the elastic thickness values decrease from the northeast (25 km) to the southwest (7 km) where the plate is the most stretched. The eastern foreland crust was not rifted and underwent a simple flexural subsidence in response to orogenesis. The central sector was affected by crustal stretching. Here the basin is modeled by combining topographic and buried loads, with postrift thermal subsidence. In the western sector, the foreland basin was created mainly by postrift thermal subsidence. The eastern and central sectors are separated by the Eastern Crustal Lineament, which is one of a series of inherited transverse faults that segment the orogen.
Heterogeneous Strain Distribution and Saturation of Geometrically Necessary Dislocations in a Ferritic–Pearlitic Steel during Lubricated Sliding
Authors: Linz Mathias , Rodríguez Ripoll Manel , Pauly Christoph , Bernardi Johannes , Steiger‐Thirsfeld Andreas , Franek Friedrich , Mücklich Frank , Gachot Carsten
Published: January 2018

The microstructural evolution of ferritic–pearlitic steel is studied during unidirectional sliding under boundary lubrication using a ball‐on‐flat configuration. Dislocation activity as a function of distance to surface is determined using orientation gradients by electron backscatter diffraction in logarithmic intervals up to one million of sliding cycles. The orientation gradient results show the formation of geometrically necessary dislocations and low‐angle grain boundaries, followed by a consolidation of those grain boundaries as nanocrystalline grains. The density of geometrically necessary dislocations and low‐angle grain boundaries is observed to reach a steady state after around 100 000 cycles. Plastic strain is not homogeneously distributed within both material phases, that is, ferrite and pearlite. Most of the plastic deformation is carried by the ferritic phase. The heterogeneous strain distribution between the ferritic and the pearlitic phase observed in the electron backscatter diffraction measurements is attributed to stress incompatibilities at the grain boundaries. Dislocation pile‐up at the ferritic–pearlitic interface is observed at high resolution using transmission electron microscopy and transmission Kikuchi diffraction.
Grain Size Depending Dwell‐Fatigue Crack Growth in Inconel 718
Authors: Saarimäki Jonas , Lundberg Mattias , Moverare Johan J.
Published: January 2018

Inconel 718 is a commonly used superalloy for turbine discs in the gas turbine industry. Turbine discs are normally subjected to dwell‐fatigue as a result of long constant load cycles. Dwell‐times have been shown to give rise to increased crack propagation rates in superalloys at elevated temperatures. Dwell‐time crack propagation behavior in Inconel 718 has been tested at 550 °C using Kb test samples with 2160 s dwell‐times at maximum load and “pure fatigue” tests. The dwell‐time effect has been studied for differently processed Inconel 718, that is, fine grained bar, grain enlarged bar, and cast material. This has been done in order to investigate the effect of grain size on crack propagation. Microstructure characterization is conducted using scanning electron microscopy techniques such as electron channeling contrast imaging and electron backscatter diffraction. Time dependent crack propagation rates are strongly affected by grain size. Propagation rates increase with decreasing grain size, whereas crack tip blunting increased with increasing grain size.
Light‐Driven Janus Hollow Mesoporous TiO2–Au Microswimmers
Authors: Sridhar Varun , Park Byung‐Wook , Sitti Metin
Published: January 2018

Light‐driven microswimmers have garnered attention for their potential use in various applications, such as environmental remediation, hydrogen evolution, and targeted drug delivery. Janus hollow mesoporous TiO2/Au (JHP–TiO2–Au) microswimmers with enhanced swimming speeds under low‐intensity ultraviolet (UV) light are presented. The swimmers show enhanced swimming speeds both in presence and absence of H2O2. The microswimmers move due to self‐electrophoresis when UV light is incident on them. There is a threefold increase in speed of JHP–TiO2–Au microswimmers in comparison with Janus solid TiO2/Au (JS–TiO2–Au) microswimmers. This increase in their speed is due to the increase in surface area of the porous swimmers and their hollow structure. These microswimmers are also made steerable by using a thin Co magnetic layer. They can be used in potential environmental applications for active photocatalytic degradation of methylene blue and targeted active drug delivery of an anticancer drug (doxurobicin) in vitro in H2O2 solution. Their increased speed from the presence of a hollow mesoporous structure is beneficial for future potential applications, such as hydrogen evolution, selective heterogeneous photocatalysis, and targeted cargo delivery.
Space‐Charge‐Stabilized Ferroelectric Polarization in Self‐Oriented Croconic Acid Films
Authors: Hu Laigui , Feng Rui , Wang Jiao , Bai Zilong , Jin Wei , Zhang Liuqun , Nie Qing‐Miao , Qiu Zhi‐Jun , Tian Pengfei , Cong Chunxiao , Zheng Lirong , Liu Ran
Published: January 2018

Great progress has been made recently in molecular ferroelectrics with properties even comparable to those of inorganic ferroelectrics. However, it is difficult to develop basic thin films and devices for practical applications since most molecular ferroelectrics are uniaxial. The single polar axes of crystallites inside their films, if available, are usually oriented randomly. These can induce the components without contribution to ferroelectric polarization and a large depolarization electric field to suppress polarization. In this work, it is demonstrated that uniaxial croconic acid films in two‐terminal devices, deposited by thermal evaporation, can show effective ferroelectric polarization and nonvolatile memory switching behavior with small coercive fields of 11–30 kV cm−1. The polar c‐axes in thick crystalline films (>500 nm) are found to be self‐oriented nearly at a desired direction. With the assistance of trapped charges, stable ferroelectric polarization can be achieved, in spite of the existence of nonferroelectric components. These may pave a way to utilize uniaxial molecular ferroelectrics for various applications, such as gate dielectrics, electrets, and memory devices.
Circular Gold Nanodisks with Synthetically Tunable Diameters and Thicknesses
Authors: Cui Ximin , Qin Feng , Ruan Qifeng , Zhuo Xiaolu , Wang Jianfang
Published: January 2018

2D or pseudo‐2D plasmonic Au nanocrystals, such as circular Au nanodisks, possess unique plasmonic properties. Circular Au nanodisks not only possess two large surfaces with circular symmetry but also exhibit the wide tunability for their plasmon resonance. However, the lack of effective synthetic methods for producing size‐tunable and monodispersed circular Au nanodisks hinders further studies on their properties and applications. Herein, the synthesis of uniformly sized circular Au nanodisks with synthetically tunable diameters and thicknesses is reported. By performing mild anisotropic oxidation on pregrown Au nanoplates with different thicknesses, the thicknesses of the obtained nanodisks are varied from ≈10 nm to ≈50 nm. The nanodisk diameters are tailored from ≈50 nm to ≈150 nm by controlling the oxidation time. Moreover, both homodimers and heterodimers made of circular Au nanodisks are constructed using molecular linkers. They exhibit rich plasmon modes. In particular, dark multipolar plasmon resonance modes can be excited and observed in the asymmetric heterodimers. Such circular Au nanodisks with controllable sizes, large atomically flat surfaces, and a dominant dipolar plasmon mode are ideal building blocks for constructing plasmonic assemblies and plasmon‐coupled systems with desired plasmonic properties and functions.
Wearable Supercapacitors Printed on Garments
Authors: Lee Seong‐Sun , Choi Keun‐Ho , Kim Se‐Hee , Lee Sang‐Young
Published: January 2018

Electronic garments have garnered considerable attention as a core technology for the upcoming wearable electronics era. To enable ubiquitous operation of electronic garments, they must be monolithically integrated with rechargeable power sources. Here, inspired by printing‐assisted aesthetic clothing designs, a new class of wearable supercapacitors (SCs) is demonstrated that can be directly printed on T‐shirts, which look like letters (or symbols) commonly printed on T‐shirts. The printed SCs consist of activated carbon/multiwalled carbon nanotube/ionic liquid‐based electrodes and ionic liquid/thiol‐ene polymer network skeleton/SiO2 nanoparticle‐based gel electrolytes. The rheological properties of the electrode/electrolyte pastes are fine‐tuned by varying the colloidal network structure, which affects the printing processability and formation of the nanoscale ion/electron conduction channels. To ensure the seamless unitization and design versatility of the printed SCs, the T‐shirt is sewn with electroconductive stainless steel (SS) threads prior to the printing process. Onto the SS threads acting as shape‐directing current collectors, the electrode/electrolyte pastes are sequentially stencil‐printed and sealed with water‐proof packaging films. The printed SCs exhibit exceptional form factors, flexibility, and thermal stability. Notably, the SC‐printed T‐shirts maintain their electrochemical activity upon exposure to laundering, wringing, ironing, and folding, demonstrating their potential and practical applicability as a promising electronic garment technology.
Mobile Magnetic Nanocatalysts for Bioorthogonal Targeted Cancer Therapy
Authors: Hoop Marcus , Ribeiro Ana Sofia , Rösch Daniel , Weinand Philipp , Mendes Nuno , Mushtaq Fajer , Chen Xiang‐Zhong , Shen Yang , Pujante Carlos Franco , Puigmartí‐Luis Josep , Paredes Joana , Nelson Bradley J. , Pêgo Ana Paula , Pané Salvador
Published: January 2018

The use of magnetic nanorobots to activate chemotherapeutic prodrugs represents a promising alternative to current chemotherapeutic treatments. Here, a hybrid nanowire (NW) for targeted bioorthogonally driven activation of the latent chemotherapeutic prodrug 5‐fluoro‐1‐propargyl‐uracil (Pro‐5‐FU) in in vitro and in vivo cancer models is proposed. The NWs are composed of magnetic iron (Fe) and palladium (Pd), a known bioorthogonal catalyst. In vitro tests with a cancer cell line showed no significant cytotoxic effect by the NWs. In contrast, NWs combined with Pro‐5‐FU lead to a significant reduction of cell viability, similarly to the one induced by its active chemotherapeutic counterpart 5‐fluorouracil (5‐FU). The reduction in cell viability is attributed to the catalytic activation of Pro‐5‐FU into 5‐FU. To demonstrate their targeted therapeutic abilities, magnetic fields are used to attract the FePd NWs to a predefined area within a cultured cancer cell population, causing a local Pro‐5‐FU activation, and subsequent cell death in this region. As a proof of concept, NWs are injected in cancer tumor xenografts. The intraperitoneal injection of Pro‐5‐FU significantly retards tumour growth without causing significant side effects. This work presents a novel chemotherapeutic approach combining nanorobotics and bioorthogonal activation of prodrugs as an efficient alternative to conventional chemotherapy.
Janus Microdimer Surface Walkers Propelled by Oscillating Magnetic Fields
Authors: Li Tianlong , Zhang Anning , Shao Guangbin , Wei Mengshi , Guo Bin , Zhang Guangyu , Li Longqiu , Wang Wei
Published: January 2018

Recent strides in micro‐ and nanofabrication technologies have enabled researchers to design and develop micro‐ and nanoscale robotic systems with enhanced power, functionality, and versatility. Because of their capability of remote actuation and navigation, synthetic micro‐ and nanomotors powered by oscillating magnetic fields have recently gained considerable attention. In this article, a new type of magnetic surface walker that can achieve speeds of up to 18.6 µm s−1 (≈4 body length s−1) in an oscillating magnetic field operated at 25 Hz and ≈2.7 mT is reported. Two magnetic Janus microspheres spontaneously form a microdimer via magnetic dipolar interactions, and this microdimer rolls its two “feet” back and forth in an alternating fashion. In addition to propulsion, the oscillating magnetic field can also precisely steer these surface walkers through complicated structures, and an extensive discussion of their performance in various experimental conditions is provided. The reported propulsion mechanism opens new possibilities for the design of remotely actuated microrobots for a wide range of applications.
Nanomotor‐Based Strategy for Enhanced Penetration across Vasculature Model
Authors: Peng Fei , Men Yongjun , Tu Yingfeng , Chen Yongming , Wilson Daniela A.
Published: January 2018

Here the first nanomotor‐based strategy is reported to effectively cross tumor vasculature endothelium. The designed nanomotors are based on (poly(ethylene glycol)‐b‐polystyrene and poly(acrylic acid)‐b‐polystyrene) building blocks, which further self‐assemble into polymersomes of tunable sizes (100, 300 nm). The polymersomes are readily loaded with hydrophilic model drug into the aqueous compartment. A catalytic platinum cap is then partially deposited on the surface of the polymersome via electron beam evaporation, resulting in a polymersome Janus nanomotor. In a tumor vasculature model, these cargo‐loaded polymersome nanomotors demonstrate enhanced penetration across the endothelium.
Functionalized Nanoparticles Efficiently Enhancing the Targeted Delivery, Tumor Penetration, and Anticancer Activity of 7‐Ethyl‐10‐Hydroxycamptothecin
Authors: Liu Xun , Si Jingxing , Zhang Qianzhi , Huang Qian , Gu Danxia , Yang Hao , Chen Xu , Shen Youqing , Sui Meihua
Published: January 2018

The enhanced permeability and retention (EPR) effect of tumors is much more complex than initially defined, and it alone is not sufficient for targeted delivery of nanosized agents. Meanwhile, poor tumor penetration is another major challenge for the treatment of solid tumors using nanoparticles. Development of delivery systems for SN38, the active metabolite of CPT‐11 in human and a very potent anticancer molecule, has become an attractive research area. PEGx‐p(HEMASN38)y (x and y are viable), a prodrug synthesized by using polyethylene glycol (PEG) as initiator and SN38 as monomer through atom transfer radical polymeration (ATRP) method, is previously reported. Using PEG2.4K‐p(HEMASN38)3K as a model prodrug, herein an active‐targeted strategy decorated with cys‐arg‐gly‐asp‐lys (CRGDK), a peptide specifically binds to neuropilin‐1 overexpressed by tumor vessels and tumor cells, is successfully established to further improve the delivery and efficacy of SN38. CRGDK‐functionalized PEG2.4K‐p(HEMASN38)3K (C‐SN38) nanoparticles and nonfunctionalized control (B‐SN38) are prepared with two distinct sizes, 30 and 100 nm. Their physiochemical and biological characteristics are investigated in vitro and in vivo with multiple tumor models. It is demonstrated for the first time that CRGDK functionalization can be a promising strategy for efficient delivery of SN38, and C‐SN38 is a potent drug candidate for the treatment of neuropilin‐1 overexpressing tumors.
Enzyme‐Based Glucose Sensor: From Invasive to Wearable Device
Authors: Lee Hyunjae , Hong Yongseok Joseph , Baik Seungmin , Hyeon Taeghwan , Kim Dae‐Hyeong
Published: January 2018

Blood glucose concentration is a key indicator of patients' health, particularly for symptoms associated with diabetes mellitus. Because of the large number of diabetic patients, many approaches for glucose measurement have been studied to enable continuous and accurate glucose level monitoring. Among them, electrochemical analysis is prominent because it is simple and quantitative. This technology has been incorporated into commercialized and research‐level devices from simple test strips to wearable devices and implantable systems. Although directly monitoring blood glucose assures accurate information, the invasive needle‐pinching step to collect blood often results in patients (particularly young patients) being reluctant to adopt the process. An implantable glucose sensor may avoid the burden of repeated blood collections, but it is quite invasive and requires periodic replacement of the sensor owing to biofouling and its short lifetime. Therefore, noninvasive methods to estimate blood glucose levels from tears, saliva, interstitial fluid (ISF), and sweat are currently being studied. This review discusses the evolution of enzyme‐based electrochemical glucose sensors, including materials, device structures, fabrication processes, and system engineering. Furthermore, invasive and noninvasive blood glucose monitoring methods using various biofluids or blood are described, highlighting the recent progress in the development of enzyme‐based glucose sensors and their integrated systems.
Cellulose‐Based Biomimetics and Their Applications
Authors: Almeida Ana P. C. , Canejo João P. , Fernandes Susete N. , Echeverria Coro , Almeida Pedro L. , Godinho Maria H.
Published: January 2018

Nature has been producing cellulose since long before man walked the surface of the earth. Millions of years of natural design and testing have resulted in cellulose‐based structures that are an inspiration for the production of synthetic materials based on cellulose with properties that can mimic natural designs, functions, and properties. Here, five sections describe cellulose‐based materials with characteristics that are inspired by gratings that exist on the petals of the plants, structurally colored materials, helical filaments produced by plants, water‐responsive materials in plants, and environmental stimuli‐responsive tissues found in insects and plants. The synthetic cellulose‐based materials described herein are in the form of fibers and films. Fascinating multifunctional materials are prepared from cellulose‐based liquid crystals and from composite cellulosic materials that combine functionality with structural performance. Future and recent applications are outlined.
Surface Engineering for Extremely Enhanced Charge Separation and Photocatalytic Hydrogen Evolution on g‐C3N4
Authors: Yu Yu , Yan Wei , Wang Xiaofang , Li Pei , Gao Wenyu , Zou Haihan , Wu Songmei , Ding Kejian
Published: January 2018

Reinforcing the carrier separation is the key issue to maximize the photocatalytic hydrogen evolution (PHE) efficiency of graphitic carbon nitride (g‐C3N4). By a surface engineering of gradual doping of graphited carbon rings within g‐C3N4, suitable energy band structures and built‐in electric fields are established. Photoinduced electrons and holes are impelled into diverse directions, leading to a 21‐fold improvement in the PHE rate.
Retracted: Colloidal Cobalt Phosphide Nanocrystals as Trifunctional Electrocatalysts for Overall Water Splitting Powered by a Zinc–Air Battery
Authors: Li Hui , Li Qi , Wen Peng , Williams Trey B. , Adhikari Shiba , Dun Chaochao , Lu Chang , Itanze Dominique , Jiang Lin , Carroll David L. , Donati George L. , Lundin Pamela M. , Qiu Yejun , Geyer Scott M.
Published: January 2018

Highly efficient and stable electrocatalysts, particularly those that are capable of multifunctionality in the same electrolyte, are in high demand for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR). In this work, highly monodisperse CoP and Co2P nanocrystals (NCs) are synthesized using a robust solution‐phase method. The highly exposed (211) crystal plane and abundant surface phosphide atoms make the CoP NCs efficient catalysts toward ORR and HER, while metal‐rich Co2P NCs show higher OER performance owing to easier formation of plentiful Co2P@COOH heterojunctions. Density functional theory calculation results indicate that the desorption of OH* from cobalt sites is the rate‐limiting step for both CoP and Co2P in ORR and that the high content of phosphide can lower the reaction barrier. A water electrolyzer constructed with a CoP NC cathode and a Co2P NC anode can achieve a current density of 10 mA cm−2 at 1.56 V, comparable even to the noble metal‐based Pt/C and RuO2/C pair. Furthermore, the CoP NCs are employed as an air cathode in a primary zinc–air battery, exhibiting a high power density of 62 mW cm−2 and good stability.
Self‐Powered Si/CdS Flexible Photodetector with Broadband Response from 325 to 1550 nm Based on Pyro‐phototronic Effect: An Approach for Photosensing below Bandgap Energy
Authors: Dai Yejing , Wang Xingfu , Peng Wenbo , Xu Cheng , Wu Changsheng , Dong Kai , Liu Ruiyuan , Wang Zhong Lin
Published: January 2018

Cadmium sulfide (CdS) has received widespread attention as the building block of optoelectronic devices due to its extraordinary optoelectronic properties, low work function, and excellent thermal and chemical stability. Here, a self‐powered flexible photodetector (PD) based on p‐Si/n‐CdS nanowires heterostructure is fabricated. By introducing the pyro‐phototronic effect derived from wurtzite structured CdS, the self‐powered PD shows a broadband response range, even beyond the bandgap limitation, from UV (325 nm) to near infrared (1550 nm) under zero bias with fast response speed. The light‐induced pyroelectric potential is utilized to modulate the optoelectronic processes and thus improve the photoresponse performance. Lasers with different wavelengths have different effects on the self‐powered PDs and corresponding working mechanisms are carefully investigated. Upon 325 nm laser illumination, the rise time and fall time of the self‐powered PD are 245 and 277 µs, respectively, which are faster than those of most previously reported CdS‐based nanostructure PDs. Meanwhile, the photoresponsivity R and specific detectivity D* regarding to the relative peak‐to‐peak current are both enhanced by 67.8 times, compared with those only based on the photovoltaic effect‐induced photocurrent. The self‐powered flexible PD with fast speed, stable, and broadband response is expected to have extensive applications in various environments.
Fused Tris(thienothiophene)‐Based Electron Acceptor with Strong Near‐Infrared Absorption for High‐Performance As‐Cast Solar Cells
Authors: Li Tengfei , Dai Shuixing , Ke Zhifan , Yang Langxuan , Wang Jiayu , Yan Cenqi , Ma Wei , Zhan Xiaowei
Published: January 2018

A fused tris(thienothiophene) (3TT) building block is designed and synthesized with strong electron‐donating and molecular packing properties, where three thienothiophene units are condensed with two cyclopentadienyl rings. Based on 3TT, a fused octacylic electron acceptor (FOIC) is designed and synthesized, using strong electron‐withdrawing 2‐(5/6‐fluoro‐3‐oxo‐2,3‐dihydro‐1H‐inden‐1‐ylidene)‐malononitrile as end groups. FOIC exhibits absorption in 600–950 nm region peaked at 836 nm with extinction coefficient of up to 2 × 105m–1 cm–1, low bandgap of 1.32 eV, and high electron mobility of 1.2 × 10–3 cm2 V–1 s–1. Compared with its counterpart ITIC3 based on indacenothienothiophene core, FOIC exhibits significantly upshifted highest occupied molecular orbital level, slightly downshifted lowest unoccupied molecular orbital level, significantly redshifted absorption, and higher mobility. The as‐cast organic solar cells (OSCs) based on blends of PTB7‐Th donor and FOIC acceptor without additional treatments exhibit power conversion efficiencies (PCEs) as high as 12.0%, which is much higher than that of PTB7‐Th: ITIC3 (8.09%). The as‐cast semitransparent OSCs based on the same blends show PCEs of up to 10.3% with an average visible transmittance of 37.4%.