bluuebunny/crossref_metadata_2025 huggingface dataset:
The Unrealism of Aristotle’s Metaphysics?
Authors: Dudley John
Published: June 2018

In this paper, I aim to show that Aristotle’s metaphysics belongs to an unrealist tradition in ancient philosophy, deriving from Anaximander, Pythagoras, Parmenides and Plato.
A Critique of Richard Sorabji’s Interpretation of Aristotle
Authors: George Marie I.
Published: June 2018

A correct understanding of experience (empeiría) is crucial for understanding the difference between human and non-human animals. Richard Sorabji interprets Aristotle to be affirming that experience in non-human animals is the same thing as a rudimentary universal, and that the individual who possesses experience achieves his goal by the application of low level univer-sals. I argue that this is neither a correct understanding of Aristotle’s statements in the Posterior Analytics, Metaphysics, and Nicomachean Ethics, nor is it true to the facts. Sorabji is misled, first, by the fact that experience can be regarded as a rudimentary universal (though not a true universal) in humans, and secondly by the fact that people of experience often possess universals that pertain to their actions. As to the latter, I show that people of experience do not succeed in virtue of possessing universals. As to the former, I point out that regarding experience as a rudimentary universal presupposes that the being that possesses them goes on to acquire true universals, something Sorabji fails to show. The presence of a modicum of experience in some non-human animals, thus, does not show that these beings share with us the capacity for knowledge of universals.
Aristotle on the Pleasure of Courage
Authors: Holberg Erica A.
Published: June 2018

Because virtuous action is the fulfillment of our nature and so is constitutive of good living, Aristotle argues for a conceptual connection be-tween virtuous action and pleasure. Yet courage does not seem to conform to this account of virtuous action. Because courageous action involves confronting the fearful, which is painful, and because courageous action can fail to achieve the desired (and presumably pleasant) goal, it seems contrary to experience to claim that all truly courageous action is pleasant. I offer a defense of Aristotle’s claim that courageous action is necessarily pleasant. To do this, I give a more detailed explanation of the hierarchical, metaphysical relation between process and activity in courageous action. Virtuous activity, as instantiated in courageous actions, is necessarily pleasant because it is an end-in-itself and complete, and so requires pleasure as the full engagement of the agent in the action.
Socrates as a ‘Radical’ Politician
Authors: Kurihara Yuji
Published: June 2018

In Plato’s early dialogues Socrates seems to make a contradictory statement about politics. In the Apology he denies his commitment to political activity in Athens, whereas in the Gorgias he declares that he is the only politician in his time, using the ‘true political craft’. How can we understand his prima facie contradictory statement? In this paper, I aim to answer this question by showing that Socrates is a ‘radical’ politician in democratic Athens, who keeps prompting each individual to care for the soul and the truth. For this aim, I first clarify usual ‘political’ activities in Athens in terms of the public-private dichotomy. Then, I elucidate the political meaning of Socrates’ philosophy in “the semi-public sphere” that he discovers for his politics between the public sphere (e.g., the Assembly and the courts) and the private sphere (e.g., the oikos). In the semi-public sphere, such as the Agora, Socrates helps his fellow citizens establish their true selves, independently of ‘the politics of reputation’. Finally, I conclude that Socrates’ statement about politics is not self-contradictory, although Plato has Socrates pointing out the important use of ‘the true rhetoric’ in the presence of many people.
The Principle of Non-contradiction in Metaphysics IV
Authors: Martins Antonio Manuel
Published: June 2018

In this paper, I wish to take account of the formulation of the PNC in Aristotle (1005b19-20) from a metaphysical point of view. After some comments on the arguments presented in the Aristotelian text, I will briefly discuss: 1) the highly topical principle in metaphysics understood as a ‘four-category ontology’ (Lowe 2005) or newly defined as “the most general attempt to make sense of things” (Moore 2012); 2) the challenge to this principle, coming from the so-called ‘aletheists’ or from ‘Hyper-physics’.
Plato’s Use of Shadow-painting as a Metaphor for Deceptive Speech
Authors: Petraki Zacharoula
Published: June 2018

Contrary to the traditional viewpoint which interpreted Plato’s stance towards poetry as derogatory, more recently scholars have rightly argued that Plato’s treatment of painting is too complicated to be dismissed as negative only. Painting is for Plato a well-adapted analogy which allows him to discuss highly intricate philosophical issues, as, for example, the relationship of the forms with our earthly realm of sense-perception. It also provides him with useful vocabulary to conduct his philosophical investigations. In this paper, I focus on Plato’s employment of one particular pictorial technique, that of shadow-painting (skiagraphia). I argue that this innovative 5th century technique served Plato as a metaphor for discussing the intricate philosophical issue of opposition and antithesis (ta enantia). In specific terms, Plato associates the technique of skiagraphia with the poets, sophists and the unsophisticated non-philosophical majority.
The Accident and its Causes: Pseudo-Alexander on Aristotle (Metaphysics Ε3)
Authors: Salis Rita
Published: June 2018

Pseudo-Alexander’s commentary in Metaphysics Ε3 is one of the three ancient commentaries which came down to us together with Ascepius’s commentary and Pseudo-Philoponus’s one, in Latin. Pseudo-Alexander’s work, in particular, constitutes the source of interpretation of the Aristotelian text for many modern scholars. In chapter 3 Aristotle shows that there are causes of accidental being, which are generable and destructible without ever being in course of being generated or destroyed. This problem is one of the most difficult and controversial for Aristotle. The thesis is explained by Aristotle with examples concerning past and future events. Pseudo-Alexander considers them as referring to accidental causes. The exegete’s explanation of both cases introduces some elements which are totally extraneous to the Aristotelian text, but nevertheless it could be helpful to cast some light on the understanding of the most controversial passages. In the final passage, Aristotle raises the question of what kind of cause the accident leads to, whether to the material or to the final or to the efficient cause. It is apparently left without an answer. Pseudo-Alexander gives a plausible solution, which is nonetheless probably only partial. The chapter was also examined with reference to the problem of determinism in Aristotle.
On Contents Division of Ancient Greek Philosophy
Authors: Zhang Shaoyu
Published: June 2018

The history of Western philosophy usually divides the ancient Greek philosophy into three parts, namely, natural science, ethics, and logic. The author deems that the ancient Greek philosophy should be divided into two categories: speculative philosophy and practical philosophy, for which writings of Plato and Aristotle provide sufficient grounds.
The Aristotelian Active Intellect on the Basis of the Actuality-potentiality Dichotomy
Authors: Zoga Christina
Published: June 2018

The aim of this paper is to give an account of the nature, the essence and the qualities of the soul, according to Aristotle’s book De anima. Particularly, the active intellect was a concept Aristotle described that requires an understanding of the actuality-potentiality dichotomy. The philosopher is trying to explain how the human intellect passes from its original state, in which it does not think, to a subsequent state, in which it does. However, during his analysis he deals with some really important problematic points which have caused much confusion over the centuries. My aim is to show this actuality-potentiality dichotomy in accordance to Aristotle’s philosophical distinctions, but also to provide a structure of analysis through which the problematic ideas of Aristotle arise on their own.
Mediação pedagógica na relação com universitários com deficiência
Authors: Pieczkowski Tania Mara Zancanaro
Published: June 2018

Este artigo é resultado de um estudo que objetivou investigar o processo de mediação pedagógica entre docentes e estudantes com deficiência na aula universitária. Está vinculado a uma pesquisa mais ampla, cujo objetivo foi tensionar o processo de inclusão de estudantes com deficiência na educação superior e compreender os seus efeitos na docência. O material empírico, gerado por meio de entrevistas narrativas realizadas com dez professores de estudantes com deficiência em diferentes cursos de graduação, foi examinado pela perspectiva da análise do discurso, amparada em referenciais foucaultianos. O texto evidencia o empenho docente em promover a inclusão e aprendizagem e constituir-se como professor mediador. O estudo aponta que os professores são subjetivados pelos discursos da inclusão, o que resulta em posturas amorosas e solidárias. A complexidade do processo torna-se explícita quando os professores vivenciam esse desafio e necessitam reestruturar suas práticas pedagógicas. Exercer a docência com “o diferente” é uma possibilidade para que o profissional de distintas áreas do conhecimento atuante na educação superior descubra que mesmo que domine o conteúdo específico e acumule títulos acadêmicos isso não basta, pois a docência é outra profissão, é o encontro com o novo, com o imprevisível.
Oppression and Suppression: The Lingering Controversy Surrounding the Meaning of the Battle of Okinawa in Japanese Memory
Authors: Shen Weija Vicky
Published: June 2018

Historical facts are sealed, but the memory of a particular history changes from one generation to the next. The highly politicized nature of historical memory determined that only one interpretation can be right at a time. Yet when individual memories contradict what is taught publicly, such gap creates an identity conflict within generations of war survivors. Such is the conventionality of Okinawa’s unique history. Focusing on the relationship between “memory” and “identity,” Countering this conception is the suppressed memories of individuals whose recollection challenged the conventional portrayal of victimhood. Drawing on the second-generation war survivor Medoruma Shun’s fictional novella Droplets as primary document, this paper explores the conflict of identities of Okinawans from a perspective of “memory.” Emphasizing the consequence of prolonged war trauma created by the lapses in public and private memories, the paper points to the bridge of the two as a potential gateway to resolve not only identity conflicts within individual war survivors, but collective healing as a group in reconciliation with its own pastcrimes.
New England Watersheds: A Data Driven Portrait of Water Pollution in the North Eastern United States
Authors: Morales Luis A
Published: June 2018

This paper examines the difference between a river that has had no human intervention and rivers with various amounts. huamn influence were evaluated through stream chemistry to determine each one’s overall water quality. water’s composition changes as it falls from the sky and flows over ground. This research makes use of the water chemistry data provided by the Hubbard Brook Experimental Forest as well as from the New England Costal Basin National Water Quality Assessment. The data was used to compute monthly averages of ions such as Sodium, Chloride, Calcium and Magnesium. These averages were graphed and the trends analyzed. Data about each river’s drainage area, surrounding population density, and land usage lend insight to the reason for each river’s chemical composition. The study concluded that the land usage around a river has an effect on the chemical composition of the waters. The rivers surrounded by urban areas had significantly more total dissolved solids and high levels of dissolved sodium chloride, especially during the winter months. This is Evidence that anthropogenic effects controlled the stream chemistry.
Gender and Higher Education: Increasing Exposure of Harassment and Pay Gaps
Authors: Hazelkorn Ellen
Published: June 2018

In Ireland and the United Kingdom, public discourse around issues of sexual harassment and promotion and pay gaps is increasing. A lack of research, combined with a lack of understanding, means the full scale is unknown, and universities lack basic guidelines. Narrow definitions of excellence also shape academic culture. But action is slowly taking hold. The take-away is that nothing moves institutions fasterthan compliance and money.
India and China: Two Major Higher Education Hubs in Asia
Authors: Lavakare P.J.
Published: June 2018

Both China and India have large and diverse higher education systems. Students from bothcountries are keen to enter the global employment market. It is this challenge that demands the respective national education systems produce “global citizens” with the high-quality, diverse, and international educational backgrounds needed on the global market. This article briefly reviews the international education status of India and China and highlights some crucial parameters governing the two systems.
Nicotinamide adenine dinucleotide is transported into mammalian mitochondria
Authors: Davila Antonio , Liu Ling , Chellappa Karthikeyani , Redpath Philip , Nakamaru-Ogiso Eiko , Paolella Lauren M , Zhang Zhigang , Migaud Marie E , Rabinowitz Joshua D , Baur Joseph A
Published: June 2018

Mitochondrial NAD levels influence fuel selection, circadian rhythms, and cell survival under stress. It has alternately been argued that NAD in mammalian mitochondria arises from import of cytosolic nicotinamide (NAM), nicotinamide mononucleotide (NMN), or NAD itself. We provide evidence that murine and human mitochondria take up intact NAD. Isolated mitochondria preparations cannot make NAD from NAM, and while NAD is synthesized from NMN, it does not localize to the mitochondrial matrix or effectively support oxidative phosphorylation. Treating cells with nicotinamide riboside that is isotopically labeled on the nicotinamide and ribose moieties results in the appearance of doubly labeled NAD within mitochondria. Analogous experiments with doubly labeled nicotinic acid riboside (labeling cytosolic NAD without labeling NMN) demonstrate that NAD(H) is the imported species. Our results challenge the long-held view that the mitochondrial inner membrane is impermeable to pyridine nucleotides and suggest the existence of an unrecognized mammalian NAD (or NADH) transporter.
Sex-based differences in anti-predator response of crickets to chemical cues of a mammalian predator
Authors: Tanis Brian P. , Bott Bradley , Gaston Brian J.
Published: June 2018

Anti-predator behaviors like vigilance or hiding come at the expense of other fitness increasing behaviors such as foraging. To compensate for this trade-off, prey assess predation risk and modify the frequency of anti-predator behaviors according to the likelihood of the threat. In this study, we tested the ability of house crickets (Acheta domesticus) to indirectly assess predation risk via odors from a mammalian predator, Elliot’s short-tailed shrew (Blarina hylophaga). As natural differences in encounter rates and predation risk differs between sexes, we tested if male and female crickets perceive similar rates of predation risk from the presence of shrew odor measured via anti-predator behavioral response. Crickets were placed in enclosed, cardboard-lined chambers either treated with shrew odor or control, along with a food source. Time until foraging was measured for each individual and compared across treatment and sex. We found that in the presence of shrew odor, female crickets delayed foraging while males showed no response. These results suggest adult crickets can use chemical cues to detect mammalian predators. Furthermore, we demonstrate that female crickets associate greater predation risk from shrew predators than do male crickets, which are more stationary yet acoustically conspicuous. As predation risk potentially differs drastically for each sex, changes to the operational sex ratios of wild cricket populations could be influenced by the identity of the predator community.
Cortical bone adaptation and mineral mobilization in the subterranean mammalBathyergus suillus(Rodentia: Bathyergidae): effects of age and sex
Authors: Montoya-Sanhueza Germán , Chinsamy Anusuya
Published: June 2018

The patterns of bone modeling and mineral mobilization (skeletal homeostasis) among mammals other than humans and laboratory rodents are still poorly known. In this study we assessed the pattern of bone formation and bone resorption in the femur of a wild population of Cape dune molerats,Bathyergus suillus(n= 41) (Bathyergidae), a solitary subterranean mammal with a marked extended longevity among rodents, and which also lives in a naturally deficient state of vitamin D. In order to determine ontogenetic and sex effects on histomorphometric parameters of transversal undecalcified bone sections, two-way ANOVA, linear mixed-effects model and regression statistical analyses were performed. During ontogeny,B. suillusincreased their cross sectional area, cortical area and cortical thickness, and most importantly, they showed scarce endosteal bone resorption which resulted in a retained medullary cavity size during ontogeny. This resulted in a positively imbalanced bone modeling, where bone formation considerably surpasses bone loss by almost 100-fold in adulthood. This differs markedly from other terrestrial mammals with relatively thin cortical walls. Regarding bone loss and remodeling, three main processes involving intracortical resorption were observed: modeling-related bone loss in early postnatal growth; secondary osteon formation occurring in both sexes; and subendosteal secondary reconstruction observed only in females. The latter is accompanied by females having six-fold more relative bone loss than males, which is evidenced by the development of enlarged resorption cavities (RCs) distributed circumferentially around the medullary cavity. Males have smaller, more circular and randomly distributed RCs. In general, our data indicate no age-related decline in mineral content inB. suillus, and provides strong support for a pattern of sexual dimorphism in skeletal homeostasis, similar to that occurring in humans and other mammals, with females losing more bone throughout aging as compared to males due to reproductive factors. Interestingly as well, despite the high mechanical loads experienced during burrow construction, bone remodeling inB. suillusis kept at very low levels throughout their lifespan, and dense Haversian tissue never forms. This study represents the first comprehensive assessment of skeletal homeostasis in a subterranean mammal, and it enables a better understanding of the complex processes governing the acquisition and maintenance of bone properties in this species with extraordinary fossorial adaptations.
How well do force fields capture the strength of salt bridges in proteins?
Authors: Ahmed Mustapha Carab , Papaleo Elena , Lindorff-Larsen Kresten
Published: June 2018

Salt bridges form between pairs of ionisable residues in close proximity and are important interactions in proteins. While salt bridges are known to be important both for protein stability, recognition and regulation, we still do not have fully accurate predictive models to assess the energetic contributions of salt bridges. Molecular dynamics simulation is one technique that may be used study the complex relationship between structure, solvation and energetics of salt bridges, but the accuracy of such simulations depends on the force field used. We have used NMR data on the B1 domain of protein G (GB1) to benchmark molecular dynamics simulations. Using enhanced sampling simulations, we calculated the free energy of forming a salt bridge for three possible lysine-carboxylate ionic interactions in GB1. The NMR experiments showed that these interactions are either not formed, or only very weakly formed, in solution. In contrast, we show that the stability of the salt bridges is overestimated, to different extents, in simulations of GB1 using seven out of eight commonly used combinations of fixed charge force fields and water models. We also find that the Amber ff15ipq force field gives rise to weaker salt bridges in good agreement with the NMR experiments. We conclude that many force fields appear to overstabilize these ionic interactions, and that further work may be needed to refine our ability to model quantitatively the stability of salt bridges through simulations. We also suggest that comparisons between NMR experiments and simulations will play a crucial role in furthering our understanding of this important interaction.
Sorption to soil, biochar and compost: is prediction to multicomponent mixtures possible based on single sorbent measurements?
Authors: Kah Melanie , Sigmund Gabriel , Manga Chavez Pedro Luis , Bielská Lucie , Hofmann Thilo
Published: June 2018

Amendment with biochar and/or compost has been proposed as a strategy to remediate soil contaminated with low levels of polycyclic aromatic hydrocarbons. The strong sorption potential of biochar can help sequestering contaminants while the compost may promote their degradation. An improved understanding of how sorption evolves upon soil amendment is an essential step towards the implementation of the approach. The present study reports on the sorption of pyrene to two soils, four biochars and one compost. Detailed isotherm analyzes across a wide range of concentration confirmed that soil amendments can significantly increase the sorption of pyrene. Comparisons of data obtained by a classical batch and a passive sampling method suggest that dissolved organic matter did not play a significant role on the sorption of pyrene. The addition of 10% compost to soil led to a moderate increase in sorption (<2-fold), which could be well predicted based on measurements of sorption to the individual components. Hence, our result suggest that the sorption of pyrene to soil and compost can be relatively well approximated by an additive process. The addition of 5% biochar to soil (with or without compost) led to a major increase in the sorption of pyrene (2.5–4.7-fold), which was, however, much smaller than that suggested based on the sorption measured on the three individual components. Results suggest that the strong sorption to the biochar was attenuated by up to 80% in the presence of soil and compost, much likely due to surface and pore blockage. Results were very similar in the two soils considered, and collectively suggest that combined amendments with compost and biochar may be a useful approach to remediate soils with low levels of contamination. Further studies carried out in more realistic settings and over longer periods of time are the next step to evaluate the long term viability of remediation approaches based on biochar amendments.
Cytochrome b5 enhances androgen synthesis by rapidly reducing the CYP17A1 oxy‐complex in the lyase step
Authors: Duggal Ruchia , Denisov Ilia G. , Sligar Stephen G.
Published: June 2018

Cytochrome P450 17A1 (CYP17A1) catalyzes the synthesis of androgens from the steroid precursors pregnenolone and progesterone in a two‐step reaction process: allylic hydroxylation and carbo‐carbon bond scission. Cytochrome b5 (Cyt‐b5) is a stimulator of the second lyase reaction, but the chemical mechanism is unclear. We have shown previously that this stimulatory effect requires redox active Cyt‐b5. To investigate the origin of the lyase reaction enhancement by electron transfer from Cyt‐b5, we measured the reduction rates of oxy‐ferrous substrate‐bound CYP17A1 by Cyt‐b5 and by cytochrome P450 reductase (CPR) coincorporated in Nanodiscs using stopped flow spectroscopy. We observed that Cyt‐b5 reduces oxy‐ferrous CYP17A1 10‐fold faster than CPR, with the rate similar to that observed in a ternary complex of all three proteins.
Multiphoton 3D Microprinting of Protein Micropatterns with Spatially Controlled Heterogeneity – A Platform for Single Cell Matrix Niche Studies
Authors: Huang Nan , Li Chuen Wai , Chan Barbara Pui
Published: June 2018

Reconstituting the biomimetic cell niche in vitro is important as it allows to determine how niche factors may affect cellular fate processes. Many biofabrication and micropatterning technologies are developed to achieve this goal. However, the critical outstanding challenges are the capabilities to spatially control the micropatterns and to decouple the different niche factors. Multiphoton microfabrication is an emerging technology with unique advantages. A multiphoton 3D microprinting platform has been previously established to create protein microstructures and micropatterns with sub‐micrometer resolution and its ability to control the topological features, porosity, and mechanical properties of microprinted protein cell niche has been demonstrated. Here, it is demonstrated that the multiphoton microprinting technology is able to precisely control the local density of the matrix niche factor, and more importantly, spatially control and decouple the mechanical and matrix niche factors. The results show that 1) the micropatterned matrix niche retains its bioactivities; 2) mesenchymal stem cells (MSCs) are able to sense the elastic modulus of the cell niche when the mechanical and matrix niche factors are decoupled; and 3) MSCs prefer to bind to and spread on fibronectin among other matrix proteins. These results path the way to future development of a “programmable” cell niche platform.
Nanograssed Micro‐V‐Groove Architectures for Continuous Dropwise Condensation and Droplet Directional Movement
Authors: Dong Jian , Dong He , Jin Yanli , Sun Li , Ye Senbin
Published: June 2018

Engineering dropwise condensation on superhydrophobic surfaces (SHSs) has a wide range of applications from thermal management to water harvesting technologies. In this study, the hierarchical nanograssed micro‐V‐groove architectures are fabricated on copper surfaces for dropwise condensation and quick directional droplet departure. An optical microscope and a camera are adopted to investigate the spontaneous motions of condensate droplets on nanograssed micro‐V‐groove SHSs. The results show that the motions of condensate droplets on V‐groove slope surfaces appear quicker, more spontaneous, and more continuous, and reservoir droplets in V‐grooves appear more larger and more easy‐rolling. The phenomenon is explained by the critical radii of the rolling condensate droplets on V‐groove slope surfaces and maximum radii of the rolling reservoir droplets. In addition, water collection experiments are done, which shows that nanograssed V‐groove SHSs have better capacities of water collection than the nanograssed flat SHS. The smaller the V‐groove angle is, the better water collection capacity the SHS has. The synergistic cooperation between micro‐V‐grooves and nanograss contributes directly to the dropwise condensation process, which enhances vapor–liquid phase change efficiency. Exploiting such multiscale coupling effects can help us design optimal condensation surfaces for high performances of phase‐change cooling and water self‐catchment systems.
PbI2/CH3NH3Cl Mixed Precursor–Induced Micrometer‐Scale Grain Perovskite Film and Room‐Temperature Film Encapsulation toward High Efficiency and Stability of Planar Perovskite Solar Cells
Authors: Deng Kaimo , Liu Zhongze , Xin Yu , Li Liang
Published: June 2018

The power conversion efficiency and the stability are the most important figures of merit for perovskite solar cells which attract increasing attention in recent years. Herein, the growth of high‐quality perovskite films with micrometer‐scale grain size through sequential deposition is first reported using PbI2/CH3NH3Cl mixed precursors during the first step of deposition. The amount of CH3NH3Cl in the precursor has a great influence on the morphology of perovskite films and the device performance. Compared with traditional sequential deposition with pure PbI2 in the first step, this method renders the perovskite solar cells with an improved power conversion efficiency up to 18.7% and reduced hysteresis. In addition, the fluorinated carbon film prepared at room temperature is reported as an encapsulation layer for perovskite solar cells. The compact and hydrophobic thin film can effectively isolate the device from moisture and oxygen, leading to the largely improved stability in the air. This study not only reveals the effect of chlorine doping on perovskite film formation in the first step of sequential deposition, but also provides a new film encapsulation strategy to improve the device stability in ambient air toward future application.
High‐Performance Low‐Voltage‐Driven Phototransistors through CsPbBr3–2D Crystal van der Waals Heterojunctions
Authors: Huo Chengxue , Liu Xuhai , Wang Ziming , Song Xiufeng , Zeng Haibo
Published: June 2018

Combining halide perovskites and 2D materials to form heterojunctions is a potential excellent strategy to design high‐performance phototransistors. However, a standard perovskite/2D material heterojunction is not fully realized, because either of the active material usually directly bridges across the opposite metal electrodes in the transistor platform. Here, phototransistors are fabricated based on high‐quality van der Waals grown CsPbBr3 and MoS2, in which CsPbBr3 and MoS2 are overlapped only within the transistor channel. The phototransistors based on this standard CsPbBr3/MoS2 heterojunction exhibit excellent optical detection ability and field‐effect characteristics at a drain–source voltage as small as 0.5 V. The rise and fall times of the phototransistor are 2.5 and 1.8 ms, respectively. The hole mobility is calculated to be 0.08 cm2 V−1 s−1 in darkness, and 0.28 cm2 V−1 s−1 under the 442 nm laser illumination. All of the measurements are conducted at room temperature in ambient air, indicating the excellent robustness of the CsPbBr3/MoS2 heterojunction. This work provides a new strategy to minimize the device size by using low‐voltage‐driven, air‐stable perovskite/2D material heterojunctions.
Tuneable Thermal Emission Using Chalcogenide Metasurface
Authors: Cao Tun , Zhang Xinyu , Dong Weiling , Lu Li , Zhou Xilin , Zhuang Xin , Deng Junhong , Cheng Xing , Li Guixin , Simpson Robert E.
Published: June 2018

Modulation of thermal radiation is an essential element of infrared sensing and imaging, thermal infrared light sources, camouflage, and thermophotovoltaics. Recently, tuneable thermal emission of nanophotonic structures has been demonstrated. However, most of the current strategies involve controlling single spectral thermal emission in the far‐infrared region, and blue shifting their resonances to the shorter wavelength region is rarely explored. Moreover, fast modulation of multispectral thermal radiation remains challenging. In this work, the dynamic control of multispectral thermal emission from 2 to 4 µm from an ultrathin reconfigurable metasurface is experimentally presented based on Au/SiO2/Ge2Sb2Te5/Au multilayer. This metadevice contains several integrated thermal emitters of various wavelengths, each of which consists of gold (Au) squares array with different widths. A tuning of multispectral absorptivity (emissivity) can be achieved by transiting the state of Ge2Sb2Te5 from amorphous to crystalline. A heat‐transfer model is developed to demonstrate that the reversible switching of multispectral thermal emission can be achieved in just 300 ns. The experimental demonstration along with the theoretical framework lays the foundation for designing high‐speed reconfigurable multispectral thermal emitters, which, as expected, will initiate a new route to thermal engineering.
Optically Driven Soft Micro Robotics
Authors: Nocentini Sara , Parmeggiani Camilla , Martella Daniele , Wiersma Diederik S.
Published: June 2018

The miniaturization of robots and actuators down to the micrometer length scale constitutes a fascinating technological challenge. Their development faces fabrication issues due to the small dimensions and their design must take into account how physics laws behave on those length scales. Last but not least, a major issue is energy delivery and management. In this scenario, light emerges as a versatile tool for the fabrication and, even more importantly, as an energy source. Optically driven micromachines—in which optical stimuli can be efficiently converted into mechanical work—have been realized in various contexts. This Review collects recent advances in this field, focusing on optical micro robots realized in soft polymers. Starting from an overview of the photoresponsive materials that have been employed, the various designs and realizations of such devices are shown exhibiting tasks and capabilities like swimming, walking, and the manipulation of microscopic objects. In the last part, frontiers studies in the integration of polymeric structures with biological organisms are shown. In many of the reported studies, untethered operation is a key issue, seen as a fundamental requirement toward the development of smart robots that can autonomously perform tasks and respond to their environment.
Superradiantly Limited Linewidth in Complementary THz Metamaterials on Si‐Membranes
Authors: Keller Janine , Haase Johannes , Appugliese Felice , Rajabali Shima , Wang Zhixin , Paravicini‐Bagliani Gian Lorenzo , Maissen Curdin , Scalari Giacomo , Faist Jérôme
Published: June 2018

Complementary double split ring THz resonators fabricated on a 10 µm thin Si‐membrane are studied. The linewidths of the fundamental LC mode and dipolar mode are drastically narrowing with increased resonator spacing. The extracted decay rate of the LC mode as a function of the resonator density shows a linear dependence, evidencing a collective superradiant effect of the resonator array. Furthermore, it is shown that a metamaterial can be designed for a low superradiant broadening of the resonance at high resonator densities, that is, in the metamaterial condition. The use of a thin membrane as a substrate is crucial, since it shifts the THz surface plasmon polaritons modes to much higher frequencies, preventing them to couple to the LC mode and unveiling the superradiant broadening mechanism for a large range of lattice spacings. At higher frequencies, not interfering with the high Q LC mode, other additional modes, which are ascribed to photonic crystal modes, form in the Si‐membrane. The angle‐dependent band structure is mapped and corresponding simulated electric field distributions are shown.
Organic Photodetectors with Gain and Broadband/Narrowband Response under Top/Bottom Illumination Conditions
Authors: Wang Wenbin , Du Mingde , Zhang Miao , Miao Jianli , Fang Ying , Zhang Fujun
Published: June 2018

Organic photodetectors (OPDs) possessing broadband/narrowband photodetection capability and gain have great potential in integrated optoelectronics products. In this work, OPDs with a device structure of ITO/poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)/thick active layer/semitransparent Al electrode exhibit the extraordinary functions, gain and bidirectional photodetection capability with tunable spectral response range. For the binary OPDs with poly(3‐hexylthiophene‐2,5‐diyl) (P3HT):[6,6]‐phenyl‐C71‐butyric acid methyl ester (PC71BM) (100:1, wt/wt) as active layer, the OPDs exhibit narrowband response from 620 to 700 nm with full‐width at half maximum (FWHM) of ≈30 nm under bottom illumination condition and broadband response from 300 to 700 nm under top illumination condition, respectively. To further confirm and optimize the extraordinary functions of OPDs, ternary devices are fabricated with P3HT:poly[4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b′]dit‐hiophene‐co‐3‐fluor‐othieno[3,4‐b]thiophene‐2‐carboxylate] (PTB7‐Th):PC71BM (50:50:1, wt/wt) as active layer. The narrowband response can be adjusted to near infrared (NIR) region from 760 to 860 nm. The broadband response can be extended to NIR region with response range from 300 to 860 nm. Meanwhile, external quantum efficiency (EQE) spectral shape of the ternary OPDs becomes flatter under top illumination condition and can be kept constant under different bias. The ternary OPDs exhibit similar EQE values of ≈2000% and specific detectivity larger than 1011 Jones at −50 V bias under bottom and top illumination conditions.
Optically Addressable Photoaligned Semiconductor Nanorods in Thin Liquid Crystal Films for Display Applications
Authors: Zhang Wanlong , Schneider Julian , Chigrinov Vladimir G. , Kwok Hoi Sing , Rogach Andrey L. , Srivastava Abhishek K.
Published: June 2018

The local optical anisotropy of 1D semiconductor nanorods (NRs), which results in anisotropic absorption and polarized emission, is important for various applications. Thin films of photoaligned, oriented NRs offer not only polarized emission but also anisotropic absorption at the macroscopic scale. Based on this anisotropic absorption, two kinds of optically addressable photoemissive displays are presented, which employ polarized backlight in combination with a liquid crystal (LC) based polarization rotator to control the down conversion emission intensity of a photoaligned NR/liquid crystal polymer (LCP) composite film. The first alternative “fixed information display” utilizes pattern aligned NRs, with an orthogonal easy axis in two domains, resulting in optical contrast in neighboring domains. The second option “random information display” employs unidirectionally aligned NR films as a projection screen to display any information coded by a LC cell. It is also shown that the NR/LCP composite film can align LC in bulk, and therefore, can be integrated into a LC cell, fabricating a robust photoemissive NR display device.
A Broadband Plasmonic Metasurface Superabsorber at Optical Frequencies: Analytical Design Framework and Demonstration
Authors: Nagarajan Arvind , Vivek Kumar , Shah Manav , Achanta Venu Gopal , Gerini Giampiero
Published: June 2018

Plasmonic metasurface based superabsorbers exhibit high absorbance. While the absorption peak can be tuned by the geometry/size of the sub‐wavelength resonator, broadband absorption can be obtained by harnessing spectrally shifted resonances of multiple resonators of various size/shapes in a unit cell. Metal dispersion hinders high‐performance broadband absorption at optical frequencies and careful designing is essential to achieve good structures. A novel analytical framework is proposed for designing a broadband superabsorber which is much faster than the time consuming full‐wave simulations that are employed so far. Analytical expressions are derived for the wavelength dependency of the design parameters, which are then used in the optimization of broadband absorption. Numerical simulations report an average polarization‐independent absorption of ≈97% in the 450–950 nm spectral region with a near unity absorption (99.36%) in the 500–850 nm region. Experimentally, an average absorption over 98% is demonstrated in the 450–950 nm spectral region at 20° incident angle. The designed superabsorber is polarization insensitive and has a weak launch angle dependency. The proposed framework simplifies the design process and provides a quicker optimal solution for high‐performance broadband superabsorbers.
Ultrasoft and Highly Stretchable Hydrogel Optical Fibers for In Vivo Optogenetic Modulations
Authors: Wang Lulu , Zhong Cheng , Ke Dingning , Ye Fengming , Tu Jie , Wang Liping , Lu Yi
Published: June 2018

Optogenetics has been widely applied as a cell‐specific technique with high temporal resolution for the modulation of neural circuitry in vivo, offering potential novel treatments for neuropsychiatric diseases. However, to date, the most widely used optogenetics waveguides remain silica optical fibers, which may lead to a mismatch in the mechanical properties between the implants and neural tissues. To resolve this issue, alginate‐polyacrylamide hydrogel optical fibers can be fabricated in a simplified one‐step process, and they show significantly improved characteristics for the in vivo optogenetic applications, including low light‐propagation loss and Young's modulus, and high stretchability. After the expression of AAV‐CaMKIIα‐ChR2‐mCherry, blue light pulses are delivered into hippocampus using a hydrogel‐optrode array, and frequency‐dependent neural responses can be observed. Moreover, optogenetic stimulation through the chronic implanted hydrogel optical fibers in the primary motor cortex can considerably modulate the animal's behavior. Hydrogel fibers significantly alleviate tissue response at the implant/neural interface, compared with that observed using the silica optical fibers. Taken together, the results of this study demonstrate the feasibility and advantages of the hydrogel optical fiber use for chronic optogenetic modulation in free‐moving animals. Hydrogel implant use may allow the development of novel therapeutic strategies for the treatment of neuropsychiatric disorders.
The True Value of Disorder
Authors: López Cefe
Published: June 2018

Border regions between areas where physical problems involve very few bodies with well‐described interactions or immensely many (amenable to statistical description) are prone to fall in the category usually associated with complexity. Disorder is an important factor to consider when examining complexity. Disordered optical materials per se would not qualify as complex but when disorder is partial or merely incipient or nonlinear interactions are included, an entirely new character is added. Here, attention is paid to three examples of these kinds of optical systems. The propagation of light through diffusive media and image formation behind an opaque screen is proposed as a problem where an exact computable solution can be expected but is impractical. Analysis shows that the problem is akin to condensed matter physics concepts related to narrow leads conductance. Another condensed matter related phenomenon brought to photonics is that of localization: disorder can induce a cessation of transport when interference of scattered fields is destructive in all directions forcing light to be exponentially confined. Finally, random lasers are a problem where a disordered, open, photonic system is governed by immensely many modes interacting nonlinearly.
Solar Redox Flow Batteries: Mechanism, Design, and Measurement
Authors: Cao Liuyue , Skyllas‐Kazacos Maria , Wang Da‐Wei
Published: June 2018

The increasing public awareness of the energy crisis since the 1970s has promoted the ongoing development of energy conversion and storage systems. As a supplement to photovoltaics, photoelectrochemical cells (PECs) are among the promising solar electricity generation systems. However, the intrinsic intermittence of sunlight can never guarantee continuous electricity supply. Therefore, PECs are being developed to convert solar energy to chemical energy in the forms of fuels such as H2 and other organic chemicals. However, this technology requires massive storage systems for the solar fuels/chemicals, and complementary conversion systems for electricity generation from the solar fuels. Redox flow batteries (RFBs) are capable of large‐scale real‐time electricity storage and conversion. Both PECs and RFBs have been investigated for more than three decades, yet the integration of these two systems has not reached maturity. Hence, this review aims to give a critical overview of the state‐of‐the‐art progress in solar redox flow batteries, from the aspects of the working mechanism, device engineering, and performance evaluation.
High‐Efficiency Polymer:Nonfullerene Solar Cells with Quaterthiophene‐Containing Polyimide Interlayers
Authors: Park Euyoung , Seo Jooyeok , Han Hyemi , Kim Hwajeong , Kim Youngkyoo
Published: June 2018

Interfacial layers (interlayers) are one of the emerging approaches in organic solar cells with bulk heterojunction (BHJ) layers because the solar cell efficiency can be additionally improved by their presence. However, less attention is paid to the use of interlayers for polymer:nonfullerene solar cells, which have strong advantages over polymer:fullerene solar cells. In addition, most polymers used for the interlayers possess a low glass transition temperature (Tg). Here, it is demonstrated that two types of quarterthiophene‐containing polyimides (PIs) with high Tg (>198 °C), which are synthesized using pyromellitic dianhydride (PMDA) and cyclobutane‐1,2,3,4‐tetracarboxylic dianhydride (CTCDA), can act as an interfacial layer in the polymer:nonfullerene solar cells with the BHJ layers of poly[(2,6‐(4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)‐benzo[1,2‐b:4,5‐b′]dithiophene))‐alt‐(5,5‐(1′,3′‐di‐2‐thienyl‐5′,7′‐bis(2‐ethylhexyl)benzo[1′,2′‐c:4′,5′‐c′]dithiophene‐4,8‐dione))] (PBDB‐T) and 3,9‐bis(2‐methylene(3‐(1,1‐dicyanomethylene)‐indanone))‐5,5,11,11‐tetrakis(4‐hexylphenyl)‐dithieno[2,3‐d:2′,3′‐d′]‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene) (ITIC), or (3‐(1,1‐dicyanomethylene)‐1‐methyl‐indanone)‐5,5,11,11‐tetrakis(4‐hexylphenyl)‐dithieno[2,3‐d:2′,3′‐d′]‐s‐indaceno[1,2‐b:5,6‐b′]‐dithiophene) (IT‐M). Interestingly, the efficiency and stability of devices are improved by the PMDA‐based PI interlayers with a stretched chain structure but degraded by the CTCDA‐based PI interlayers with a bended chain structure.
Tailoring the Edge Sites of 2D Pd Nanostructures with Different Fractal Dimensions for Enhanced Electrocatalytic Performance
Authors: Yan Yucong , Li Xiao , Tang Min , Zhong Hao , Huang Jingbo , Bian Ting , Jiang Yi , Han Yu , Zhang Hui , Yang Deren
Published: June 2018

The important role of edge sites in atomically thin 2D materials serving as catalysts is already of concerned in plenty of material systems and catalytic reactions, whereas comprehensive study of the edge sites in 2D noble‐metal nanocatalysts is still lacking. Herein, for the first time, a controllable etching approach to tailor the fractal dimensions and edge sites of Pd nanosheets is developed and the edge sites in these 2D nanostructures from both structural and chemical aspects are investigated. The as‐tailored 2D Pd nanostructures with extra edge sites exhibit substantially enhanced electrocatalytic performance for the formic acid oxidation reaction (FAOR). Moreover, careful analysis of the results from electrocatalytic measurements reveals that the specific activities for the edge sites in the 2D nanostructures far exceed the activities for the low‐index planes of Pd and even dominate the overall activity exhibited by the 2D noble‐metal catalysts.
Stretchable Multiresponsive Hydrogel with Actuatable, Shape Memory, and Self‐Healing Properties
Authors: Zhang Feng , Xiong Ligui , Ai Yongjian , Liang Zhe , Liang Qionglin
Published: June 2018

Smart hydrogels with responsive behaviors have attracted tremendous attention. However, it is still a challenge to synthesize stretchable hydrogels capable of changing their original properties in response to multiple external stimuli. Here, integration of actuation function, shape memory, and self‐healing capability in a highly stretchable hydrogel under triple external triggers is achieved by rationally engineering multiple functional moieties. The hydrogel exhibits high stretchability (average relative strain (mm/mm) is >15) and excellent fatigue resistance during 100 loading cycles of 100% strain. Incorporating a moisture‐insensitive polymer film with the hydrogel, hydroactuated functionality is demonstrated. Moreover, shape memory and self‐healing abilities of the hydrogel are realized by the formation of ionic crosslinking or dynamic borate ester in conditions of multivalent cations and pH, respectively. Deformable plastic flowers are displayed in this work as a proof‐of‐concept, and it is believed that this smart hydrogel could be used in plenty of frontier fields, such as designing electronic devices, soft robotics, and actuators.