bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulating secondary organic aerosol from anthropogenic and biogenic precursors: comparison to outdoor chamber experiments, effect of oligomerization on SOA formation and reactive uptake of aldehydes
Authors: Couvidat Florian , Vivanco Marta G. , Bessagnet Bertrand
Published: November 2018

Abstract. New parameterizations for the formation of organic aerosols were developed. These parameterizations cover secondary organic aerosol (SOA) formation from biogenic and anthropogenic precursors, NOx dependency, oligomerization and the reactive uptake of pinonaldehyde. These parameterizations were implemented in a box model in which the condensation and/or evaporation of semi-volatile organic compounds was simulated by the Secondary Organic Aerosol Processor (SOAP) model to take the dynamic evolution of concentrations into account.The parameterizations were tested against several experiments carried out in previous studies in the EUPHORE outdoor chamber. Two datasets of experiments were used: the anthropogenic experiments (in which SOA is formed mainly from a mixture of toluene, 1,3,5-trimethylbenzene and o-xylene) and the biogenic experiments (in which SOA is formed mainly from α-pinene and limonene).When assuming no wall deposition of organic vapors, satisfactory results (bias lower than 20 %) were obtained for the biogenic experiments and for most of the anthropogenic experiments. However, a decrease of SOA concentrations (up to 30 %) was found when taking wall deposition of organic vapors into account (with the parameters of Zhang et al., 2014). The anthropogenic experiments seem to indicate a complex NOx dependency that could not be reproduced by the model. Oligomerization was found to have a strong effect on SOA composition (oligomers were estimated to account for up to 78 % of the SOA mass) and could therefore have a strong effect on the formation of SOA. The uptake of pinonaldehyde (which is a high-volatility semi-volatile organic compound, SVOC) onto acidic aerosol was found to be too slow to be significant under atmospheric conditions (no significant amount of SOA formed after 3 days of evolution), indicating that the parameterization of Pun and Seigneur (2007) used in some air quality models may lead to an overestimation of SOA concentrations. The uptake of aldehydes could nevertheless be an important SOA formation pathway for less volatile or more reactive aldehydes than pinonaldehyde.Regarding viscosity, a low effect of viscosity on SOA concentrations was estimated by the model, although a decrease of SVOC evaporation was found when taking it into account, as well as a lower sensitivity of concentrations to changes of temperature during the experiments.
Retrieval of liquid water cloud properties from POLDER-3 measurements using a neural network ensemble approach
Authors: Di Noia Antonio , Hasekamp Otto P. , van Diedenhoven Bastiaan , Zhang Zhibo
Published: November 2018

Abstract. This paper describes a neural network algorithm for the estimation of liquid water cloud optical properties from the Polarization and Directionality of Earth's Reflectances-3 (POLDER-3) instrument, on board the Polarization & Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar (PARASOL) satellite. The algorithm has been trained on synthetic multi-angle, multi-wavelength measurements of reflectance and polarization, and has been applied to the processing of one year of POLDER-3 data. Comparisons of the retrieved cloud properties with Moderate resolution Imaging Spectroradiometer (MODIS) products show negative biases around −2 in retrieved cloud optical thicknesses (COTs) and between −1 and −2 μm in retrieved cloud effective radii. Comparisons with existing POLDER-3 datasets suggest that the proposed scheme may have enhanced capabilities for cloud effective radius retrieval at least over land. An additional feature of the presented algorithm is that it provides COT and effective radius retrievals at the native POLDER-3 Level 1B pixel level.
Dynamic mercury methylation and demethylation in oligotrophic marine water
Authors: Munson Kathleen M. , Lamborg Carl H. , Boiteau Rene M. , Saito Mak A.
Published: November 2018

Abstract. Mercury bioaccumulation in open-ocean food webs depends on the net rate of
inorganic mercury conversion to monomethylmercury in the water column. We
measured significant methylation rates across large gradients in oxygen
utilization in the oligotrophic central Pacific Ocean. Overall, methylation
rates over 24 h incubation periods were comparable to those previously
published from Arctic and Mediterranean waters despite differences in
productivity between these marine environments. In contrast to previous
studies that have attributed Hg methylation to heterotrophic bacteria, we
measured higher methylation rates in filtered water compared to unfiltered
water. Furthermore, we observed enhanced demethylation of newly produced
methylated mercury in incubations of unfiltered water relative to filtered
water. The addition of station-specific bulk filtered particulate matter, a
source of inorganic mercury substrate and other possibly influential
compounds, did not stimulate sustained methylation, although transient
enhancement of methylation occurred within 8 h of addition. The addition
of dissolved inorganic cobalt also produced dramatic, if transient, increases
in mercury methylation. Our results suggest important roles for noncellular
or extracellular methylation mechanisms and demethylation in determining
methylated mercury concentrations in marine oligotrophic waters. Methylation
and demethylation occur dynamically in the open-ocean water column, even in
regions with low accumulation of methylated mercury.
Strength and limits of transient mid to late Holocene simulations with dynamical vegetation
Authors: Braconnot Pascale , Zhu Dan , Marti Olivier , Servonnat Jérôme
Published: November 2018

Abstract. We discuss here the first 6000 years long Holocene simulations with fully interactive vegetation and carbon cycle with the IPSL Earth system model. It reproduces the long term trends in tree line in northern hemisphere and the southward shift of Afro-Asian monsoon precipitation in the tropics in response to orbital forcing. The simulation is discussed at the light of a set of mid Holocene and pre industrial simulations performed to set up the model version and to initialize the dynamical vegetation. These sensitivity experiments remind us that model quality or realism is not only a function of model parameterizations and tuning, but also of experimental set up. They also question the possibility for bi-stable vegetation states under modern conditions. Despite these limitations the results show different timing of vegetation changes through space and time, mainly due to the pace of the insolation forcing and to internal variability. Forest in Eurasia exhibits changes in forest composition with time as well as large centennial variability. The rapid increase of atmospheric CO2 in the last centuries of the simulation contributes to enhance tree growth and counteracts the long term trends induced by Holocene insolation in the northern hemisphere. A complete evaluation of the results would require being able to properly account for systematic model biases and, more important, a careful choice of the reference period depending on the scientific questions.
Carbon–nitrogen coupling under three schemes of model representation: a traceability analysis
Authors: Du Zhenggang , Weng Ensheng , Jiang Lifen , Luo Yiqi , Xia Jianyang , Zhou Xuhui
Published: November 2018

Abstract. The interaction between terrestrial carbon (C) and nitrogen (N) cycles has been incorporated into
more and more land surface models. However, the scheme of C–N coupling
differs greatly among models, and how these diverse representations of C–N
interactions will affect C-cycle modeling remains unclear. In this study, we
explored how the simulated ecosystem C storage capacity in the terrestrial
ecosystem (TECO) model varied with three different commonly used schemes of
C–N coupling. The three schemes (SM1, SM2, and SM3) have been used in three
different coupled C–N models (i.e., TECO-CN, CLM 4.5, and O-CN,
respectively). They differ mainly in the stoichiometry of C and N in
vegetation and soils, plant N uptake strategies, downregulation of
photosynthesis, and the pathways of N import. We incorporated the three C–N
coupling schemes into the C-only version of the TECO model and evaluated
their impacts on the C cycle with a traceability framework. Our results
showed that all three of the C–N schemes caused significant reductions in
steady-state C storage capacity compared with the C-only version with
magnitudes of −23 %, −30 %, and −54 % for SM1, SM2, and
SM3, respectively. This reduced C storage capacity was mainly derived from
the combined effects of decreases in net primary productivity (NPP;
−29 %, −15 %, and −45 %) and changes in mean C residence
time (MRT; 9 %, −17 %, and −17 %) for SM1, SM2, and SM3,
respectively. The differences in NPP are mainly attributed to the different
assumptions on plant N uptake, plant tissue C : N ratio,
downregulation of photosynthesis, and biological N fixation. In comparison,
the alternative representations of the plant vs. microbe competition strategy
and the plant N uptake, combined with the flexible C : N
ratio in vegetation and soils, led to a notable spread in MRT. These results
highlight the fact that the diverse assumptions on N processes represented by
different C–N coupled models could cause additional uncertainty for land
surface models. Understanding their difference can help us improve the
capability of models to predict future biogeochemical cycles of terrestrial
ecosystems.
Evaluation of soil moisture from CCAM-CABLE simulation, satellite based models estimates and satellite observations: Skukuza and Malopeni flux towers regional case study
Authors: Khosa Floyd Vukosi , Mateyisi Mohau Jacob , van Der Merwe Martina Reynita , Feig Gregor Timothy , Engelbrecht Francois Alwyn , Savage Michael John
Published: November 2018

Abstract. Reliable estimates of daily, monthly and seasonal soil moisture are useful in a variety of disciplines. The availability of continuous in situ soil moisture observation records in Southern Africa barely exists. In this regard, process based simulation model outputs turns out to be a valuable source of climate information, which is needed for guiding farming practises and policy interventions at various spatio-temporal scales. Despite their ability to yield historic and future projections of climatic conditions, simulation model outputs often reflect a certain degree of systematic uncertainty hence it is very important to evaluate their representativeness of spatial and temporal patterns against observations. To this effect, this study presents an evaluation of soil moisture outputs from a simulation and satellite data based soil moisture products. The simulation model consists of a global circulation model known as the conformal-cubic atmospheric model (CCAM), coupled to the CSIRO Atmosphere Biosphere Land Exchange model (CABLE). The satellite based soil moisture products include; satellite observations from the European space agency (ESA) and satellite observation based model estimates from the Global Land Evaporation Amsterdam model (GLEAM). The evaluation is done for both the surface (0–10 cm) and root zone (10–100 cm) using in situ soil moisture measurements collected from two savanna sites, located in the Kruger National Park, South Africa. For the two chosen sites with different soil types and vegetation cover, the evaluation considers soil moisture time series aggregated to a monthly time scale from all the data sources. In order to reflect the inter-comparability of CCAM-CABLE simulation output, and GLEAM model estimates, a qualitative analysis of phase agreement, using wavelet analysis is presented. The onset and offset of the wet period, for the two specific sites, is calculated for each of the models and the soil moisture time series covariance between CCAM-CABLE and the GLEAM is discussed. Our results indicate that both the simulation and satellite observation based model outputs are generally consistent with the in situ soil moisture observations at the two study sites, especially at the surface. CCAM-CABLE and GLEAM inter-comparison also shows that the models are generally in phase, however with a time lag of about 12 and 20 days on average, for the surface and root zone respectively. In general the simulation compare well with the GLEAM model estimates, hence indicating that the key physical processes that drive soil moisture in CCAM-CABLE and GLEAM, at the surface and root zone, lead to an appreciable degree of mutual information. This is reinforced by a predominantly positive measure of covariance between the respective two soil moisture outputs.
Stochastic hydrogeology's biggest hurdles analyzed and its big blind spot
Authors: Rubin Yoram , Chang Ching-Fu , Chen Jiancong , Cucchi Karina , Harken Bradley , Heße Falk , Savoy Heather
Published: November 2018

Abstract. This paper considers questions related to the adoption of
stochastic methods in hydrogeology. It looks at factors affecting the
adoption of stochastic methods including environmental regulations, financial
incentives, higher education, and the collective feedback loop involving
these factors. We begin by evaluating two previous paper series appearing in
the stochastic hydrogeology literature, one in 2004 and one in 2016, and
identifying the current thinking on the topic, including the perceived data
needs of stochastic methods, the attitude in regulations and the court system
regarding stochastic methods, education of the workforce, and the
availability of software tools needed for implementing stochastic methods in
practice. Comparing the state of adoption in hydrogeology to petroleum
reservoir engineering allowed us to identify quantitative metrics on which to
base our analysis. For impediments to the adoption of stochastic hydrology,
we identified external factors as well as self-inflicted wounds. What emerges
is a picture much broader than current views. Financial incentives and
regulations play a major role in stalling adoption. Stochastic hydrology's
blind spot is in confusing between uncertainty with risk and ignoring
uncertainty. We show that stochastic hydrogeology comfortably focused on risk
while ignoring uncertainty, to its own detriment and to the detriment of its
potential clients. The imbalance between the treatment on risk on one hand
and uncertainty on the other is shown to be common to multiple disciplines in
hydrology that interface with risk and uncertainty.
The sustainable transport pathway: A holistic strategy of Five Transformations
Authors: Loo Becky , Tsoi Ka Ho
Published: November 2018

In this paper, a holistic strategy of the “Five Transformations” is introduced to offer a comprehensive and synergetic theory to tackle various daunting challenges faced by the transport sector and ultimately pave the way to sustainable transport. The Five Transformations span across city development, the economy, vehicle technology, modal-split and lifestyles at various geographical scales. Building on the current literature and empirical evidence, this paper advocates for fundamental changes in all aspects of the society beyond transportation. To move forward, this paper scrutinizes the association between land-use planning and the Five Transformations. It is clear that land-use policies are important drivers in implementing and reinforcing the policy instruments under the Five Transformations.
Um olhar Nietzschiano à Dogville: as Desordens Morais da Personagem Grace no Discurso Fílmico
Authors: Moleta Cintia , Hansen Fábio
Published: November 2018

O presente artigo tem como objeto de pesquisa o filme Dogville, de 2003, e buscou responder à seguinte questão: como se dá a aproximação entre o discurso sobre a moral em Dogville e as considerações sobre a moral de Nietzsche, tendo em vista o comportamento da personagem Grace no discurso fílmico? Para respondê-la, os objetivos foram analisar a construção do discurso sobre a moral em Dogville, relacionando-o às considerações sobre a moral de Nietzsche; e identificar as desordens morais na tomada de posição da personagem Grace de acordo com os valores que manifesta no filme. Para alcançar tais objetivos, foi utilizada a abordagem teórico-metodológica da análise do discurso de linha francesa, com os conceitos de interdiscurso, formação discursiva e posição-sujeito, que evidenciam, com eles, as desordens morais que constituem o comportamento da protagonista no filme. Dessa maneira, desliza-se um sentido moral da obra que revela um sujeito contemporâneo ambíguo e fragmentado.
The Future of Art Criticism: Objectivism Goes to the Movies
Authors: Barrowman Kyle
Published: November 2018

By virtue of an extended consideration of problems and possibilities in the discipline of film studies toward the goal of constructing an Objectivist aesthetics of cinema, this article examines some of the most pressing issues facing contemporary art criticism. Opposing tenets of an Aristotelian aesthetic tradition against tenets of a Kantian aesthetic tradition, the author attempts to resolve a number of long-standing aporias in the Objectivist aesthetics and in the philosophy of art more broadly in the hopes of charting a fruitful path for the future of art criticism.
Ayn Rand's “Integrated Man” and Russian Nietzscheanism
Authors: Grigorovskaya Anastasiya Vasilievna
Published: November 2018

The purpose of the article is to identify the influence on Ayn Rand's work of Friedrich Nietzsche in Silver Age Russia. The analysis focuses on Rand's novels We the Living, The Fountainhead, Atlas Shrugged, and some of her nonfiction philosophical essays. Thus Spake Zarathustra: A Book for All and None is the work by Nietzsche that is central to the analysis.
Money, Morality, and the Need for Entrepreneurship
Authors: Weinman Sara Michelle
Published: November 2018

In Atlas Shrugged, the observations of the character Francisco d'Anconia are used to illustrate the connection between Objectivism, morality, and economics. In response, the author demonstrates how today's socioeconomic movements not only are inconsistent with d'Anconia's view but will likely lead to further large-scale economic and moral crises, unless an economic system is established that will protect the individual's right to worthwhile production, income, and ownership.
Moderating Effect of Ethnicity on the Purchase Decisions of Females in the Beauty Care Product Market of Sri Lanka
Authors: N.S.D. Cooray , P.A.K Dias , R.P.K.N Rajapaksha , K. Bernard , H.M.U.S.R Samarasinghe
Published: November 2018

The main focal point in the eye of any marketer should be to satisfy the customer to the best possible level, in order to sustain in the ever-growing, dynamic and highly competitive marketplace. This leads them to the point where understanding the process of consumer buying behavior is of utmost importance. As the entire process of consumer buying behavior ultimately leads to their purchasing decision, deep understanding of the factors that affect this purchase decision should be the centralized core based on which all other marketing efforts should be built upon by the marketers. Based on this vitality, although these factors have already been found by past researchers in international contexts, these cannot be considered as directly applicable to the Sri Lankan context as Sri Lanka is a multiethnic country in which consumers are heavily driven by traditions and values of the ethnic group they belong to. Therefore, this study has been conducted in order to analyze the moderating effect of “Ethnicity” on the relationship between these factors and the purchasing decision.

The sample has been selected through Random Sampling and the Quantitative Research Approach has been applied. Chi-Square analysis method has been used to analyze the relationships between the independent variables (price, brand name and composition) and dependent variable (purchase decision). Two-way Anova analysis method has been used to analyze the moderating effect of the moderating variable (ethnicity) on the relationships between independent variables and the dependent variable. Based on interpretation guidelines of Chi-square test, all three independent variables, namely price, brand name and composition, affect the purchase decision of females in the beauty care product market of Sri Lanka. Thereafter, based on the interpretation guidelines of Two-way Anova, research findings of the second analysis conclude that ethnicity of the Sri Lankan females of the beauty care product market (Sinhalese, Tamils and Muslims) affect the relationships between “brand name and purchase decision” and “composition and purchase decision”, but does not affect the relationship between “price and purchase decision”.
Ecological theory provides insights about evolutionary computation
Authors: Dolson Emily L , Banzhaf Wolfgang , Ofria Charles
Published: November 2018

Evolutionary algorithms often incorporate ecological concepts to help maintain diverse populations and drive continued innovation. However, while there is strong evidence for the value of ecological dynamics, a lack of overarching theoretical framework renders the precise mechanisms behind these results unclear. These gaps in our understanding make it challenging to predict which approaches will be most appropriate for a given problem. Biologists have been developing ecological theory for decades, but the resulting body of work has yet to be translated into an evolutionary computation context. This paper lays the groundwork for such a translation by applying ecological theory to three different selection mechanisms in evolutionary computation: fitness sharing, lexicase selection, and Eco-EA. First, we use ecological ideas to establish a framework that clarifies how these selection schemes are alike and how they differ. We then build upon this framework by using metrics from ecology to gather empirical data about the underlying differences in the population dynamics that these approaches produce. Specifically, we measure interaction networks and phylogenetic diversity within the population to explore long-term stable coexistence. Notably, we find that selection methods affect phylogenetic diversity differently than phenotypic diversity. These results can inform parameter selection, choice of selection scheme, and the development of new selection schemes.
CA2 neuronal activity controls hippocampal low gamma and ripple oscillations
Authors: Alexander Georgia M , Brown Logan Y , Farris Shannon , Lustberg Daniel , Pantazis Caroline , Gloss Bernd , Plummer Nicholas W , Jensen Patricia , Dudek Serena M
Published: November 2018

Hippocampal oscillations arise from coordinated activity among distinct populations of neurons and are associated with cognitive functions. Much progress has been made toward identifying the contribution of specific neuronal populations in hippocampal oscillations, but less is known about the role of hippocampal area CA2, which is thought to support social memory. Furthermore, the little evidence on the role of CA2 in oscillations has yielded conflicting conclusions. Therefore, we sought to identify the contribution of CA2 to oscillations using a controlled experimental system. We used excitatory and inhibitory DREADDs to manipulate CA2 neuronal activity and studied resulting hippocampal-prefrontal cortical network oscillations. We found that modification of CA2 activity bidirectionally regulated hippocampal and prefrontal cortical low-gamma oscillations and inversely modulated hippocampal ripple oscillations in mice. These findings support a role for CA2 in low-gamma generation and ripple modulation within the hippocampus and underscore the importance of CA2 in extrahippocampal oscillations.
Evaluation of soil intervention values in mine tailings in northern Chile
Authors: Lam Esquenazi Elizabeth , Keith Norambuena Brian , Montofré Bacigalupo Ítalo , Gálvez Estay María
Published: November 2018

The aim of this work is to show a methodological proposal for the analysis of soil intervention values in mine tailings in order to determine the intervention requirements in the commune of Andacollo in northern Chile. The purpose of this analysis is to guide the intervention policies of both private and public organizations. The evaluation method is based on the Dutch legislation. The usability of the proposed methods depends on the available geochemical data from soil samples; in particular, we tackle the case when information regarding clay percentage in the soil is not available. We use the concepts of a threshold factor and an adjusted threshold factor to calculate a weighted intervention ranking. In order to illustrate the utility of this methodological proposal, a case study is carried out with the prescribed approach. In particular, this work presents an analysis of the elements of environmental significance related to the mining activity (Hg, Cd, Pb, As, Cu, Ni, Zn, Cr) in the commune of Andacollo, Coquimbo Region, Chile. The analyzed samples are used to determine where the intervention of tailing deposits is necessary and where a solution to these environmental liabilities is required as soon as possible. Out of the 81 samples evaluated, it was found that 18 require a potential intervention, and of these samples, seven of them are associated with abandoned tailings that, in some cases, are located close to the town center itself, one sample is associated with active tailings and the other 10 with inactive tailings.
MiR‐194 regulates nasopharyngeal carcinoma progression by modulating MAP3K3 expression
Authors: Yin Wei , Shi Lei , Mao Yanjiao
Published: November 2018

Despite the recent development of treatment strategies for nasopharyngeal carcinoma, the effective management of this disease remains a challenging clinical problem. A better understanding of the regulatory roles of miR‐194 and mitogen‐activated protein kinase kinase kinase 3 (MAP3K3) in the nasopharyngeal‐carcinoma‐related gene network is required to address this issue. Here, we measured relative expression of miR‐194 in human nasopharyngeal carcinoma tissues and normal epithelial tissues by quantitative real time PCR. We transfected cultured CNE‐1 and C666‐1 cells with miR‐194 mimics, and then examined the effects on cell proliferation, cell migration and invasion. Luciferase reporter assay was used to validate the putative binding between miR‐194 and MAP3K3. We then examined the effect of knockdown and overexpression of MAP3K3 on cell tumorigenesis. Expression of miR‐194 is significantly down‐regulated in nasopharyngeal carcinoma specimens and tumor cell lines when compared with normal controls. In addition, miR‐194 suppressed tumor cell proliferation and viability, as well as migration and invasion of carcinoma cells. We found that miR‐194 binds the 3′ untranslated region of MAP3K3, and knockdown of miR‐194 inhibited nasopharyngeal carcinoma cell proliferation, migration and invasion. In accordance, overexpression of MAP3K3 reversed the inhibitory effects of miR‐194 in carcinoma cells. This study suggests that expression of miR‐194 is down‐regulated in nasopharyngeal carcinoma, and that miR‐194 can directly target MAP3K3 to regulate tumor progression. Given the pivotal involvement of MAP3K3 in nasopharyngeal carcinoma development, targeting miR‐194 may be a novel strategy for the treatment of nasopharyngeal carcinoma.
Longitudinal assessment of anchored transponder migration following lung stereotactic body radiation therapy
Authors: McDonald Andrew M. , Colvin Tyler , Boggs D. Hunter , Spencer Sharon A. , Popple Richard A. , Clayton Ravinder , Minnich Douglas , Dobelbower Michael C.
Published: November 2018

Purpose

To assess the long‐term stability of the anchored radiofrequency transponders and compare displacement rates with other commercially available lung fiducial markers. We also sought to describe late toxicity attributable to fiducial implantation or migration.

Materials and methods

The transponder cohort was comprised of 17 patients at our institution who enrolled in a multisite prospective clinical trial and underwent bronchoscopic implantation of three anchored transponders into small (2–2.5 mm) airways. We generated a comparison cohort of 34 patients by selecting patients from our institutional lung SBRT database and matching 2:1 based on the lobe containing tumor and proximity to the bronchial tree. Assessment of migration was performed by rigidly registering the most recent follow‐up CT scan to the simulation scan, and assessing whether the relative geometry of the fiducial markers had changed by more than 5 mm. Toxicity outcomes of interest were hemoptysis and pneumothorax.

Results

The median follow‐up of patients in the transponder cohort was 25.3 months and the median follow‐up in the comparison cohort was 21.7 months. When assessing the most recent CT, all fiducial markers were within 5 mm of their position at CT simulation in 11 (65%) patients in the transponder group as compared to 23 (68%) in the comparison group (P = 0.28). One case of hemoptysis was identified in the transponder cohort, and bronchoscopy confirmed bleeding from recurrent tumor; no cases of hemoptysis were noted in the comparison cohort. No case of pneumothorax was noted in either group.

Conclusion

No significant difference in the rates of fiducial marker retention and migration were noted when comparing patients who had anchored transponders placed into small airways and a 2:1 matched cohort of patients who had other commercially available lung fiducial markers placed. In both groups, no late or chronic toxicity appeared to be related to the implanted fiducial markers.
Local Delivery and Sustained‐Release of Nitric Oxide Donor Loaded in Mesoporous Silica Particles for Efficient Treatment of Primary Open‐Angle Glaucoma
Authors: Hu Chunchun , Sun Jianguo , Zhang Yu , Chen Jian , Lei Yuan , Sun Xinghuai , Deng Yonghui
Published: November 2018

Nitric oxide (NO) donors are ideal drug candidates for reducing intraocular pressure in the treatment of glaucoma. However, poor cornea penetration, short duration of efficacy, and narrow therapeutic index of most NO donors obstruct their clinical applications in glaucoma treatment. This study reports a novel NO donor delivery system based on mesoporous silica nanoparticles that can readily overcome the above difficulties and deliver the NO‐donating drug sodium nitroprusside to the target tissues (trabecular meshwork and Schlemm's canal). Mesoporous silica nanoparticles loaded with sodium nitroprusside can produce more exogenous NO and sustain higher NO concentration in animal eye models, which significantly extend the duration of intraocular pressure reduction from 3 to 48 h with only 1/40 of the dose of sodium nitroprusside solution. These findings open up the possibility of mesoporous silica nanoparticles loading sodium nitroprusside for effective management of ocular hypertension.
Ultimate Control over Hydrogen Bond Formation and Reaction Rates for Scalable Synthesis of Highly Crystalline vdW MOF Nanosheets with Large Aspect Ratio
Authors: Shen Yuxia , Shan Bohan , Cai Hui , Qin Ying , Agarwal Ashutosh , Trivedi Dipesh B. , Chen Bin , Liu Lei , Zhuang Houlong , Mu Bin , Tongay Sefaattin
Published: November 2018

Large‐scale synthesis of van der Waals (vdW) metal–organic framework (MOF) nanosheets with controlled crystallinity and interlayer coupling strength is one of the bottlenecks in 2D materials that has limited its successful transition to large‐scale applications. Here, scalable synthesis of mBDC (m = Zn and Cu) 2D MOFs at large scales through a biphase method is demonstrated. The results show replacing water molecules with pyridine eliminates hydrogen bond formation at metal cluster sites. This prohibits tight coupling across adjacent MOF layers and sustains controllable 2D vdW MOF growth. It is further shown that control over the growth speed, crystallinity, and thickness can be achieved by addition of a controlled amount of triethylamine and formic acid to achieve highly crystalline vdW MOF nanosheets with extraordinarily high aspect ratio. The described synthesis route can easily be scaled up for large‐scale production either by deposition onto desired substrates or in crystalline layered powder form. Owing to its large lateral size, vdW nature, and high crystallinity, it is possible to perform atomic force microscopy, Kelvin probe force microscopy, and Raman measurements on the 2D MOFs. The results not only establish their vibrational properties and layer‐dependent responses but also show striking differences from other 2D inorganic materials.
Enhanced Spontaneous Polarization in Ultrathin SnTe Films with Layered Antipolar Structure
Authors: Chang Kai , Kaloni Thaneshwor P. , Lin Haicheng , Bedoya‐Pinto Amilcar , Pandeya Avanindra K. , Kostanovskiy Ilya , Zhao Kun , Zhong Yong , Hu Xiaopeng , Xue Qi‐Kun , Chen Xi , Ji Shuai‐Hua , Barraza‐Lopez Salvador , Parkin Stuart S. P.
Published: November 2018

2D SnTe films with a thickness of as little as 2 atomic layers (ALs) have recently been shown to be ferroelectric with in‐plane polarization. Remarkably, they exhibit transition temperatures (Tc
) much higher than that of bulk SnTe. Here, combining molecular beam epitaxy, variable temperature scanning tunneling microscopy, and ab initio calculations, the underlying mechanism of the Tc
enhancement is unveiled, which relies on the formation of γ‐SnTe, a van der Waals orthorhombic phase with antipolar inter‐layer coupling in few‐AL thick SnTe films. In this phase, 4n − 2 AL (n = 1, 2, 3…) thick films are found to possess finite in‐plane polarization (space group Pmn21), while 4n AL thick films have zero total polarization (space group Pnma). Above 8 AL, the γ‐SnTe phase becomes metastable, and can convert irreversibly to the bulk rock salt phase as the temperature is increased. This finding unambiguously bridges experiments on ultrathin SnTe films with predictions of robust ferroelectricity in GeS‐type monochalcogenide monolayers. The observed high transition temperature, together with the strong spin‐orbit coupling and van der Waals structure, underlines the potential of atomically thin γ‐SnTe films for the development of novel spontaneous polarization‐based devices.
Lipids: Source of Static Electricity of Regenerative Natural Substances and Nondestructive Energy Harvesting
Authors: Kim Dong Wook , Kim Sang‐Woo , Jeong Unyong
Published: November 2018

It is familiar to everyone that human skin and hair easily lose electrons and cause static electricity as they undergo friction with other materials. Such natural regenerative substances take a high ranking in the triboelectric series. Even though the static electricity of regenerative natural substances has been a long‐term curiosity in human history, it is not yet clear which of their components causes the positive static charges. This study reveals that lipid layers on the surface of regenerative substances (skin, hair, leaves, cells) and even synthetic lipids are responsible for this positive static electricity and shows that it is possible to manufacture lipid‐based triboelectric nanogenerators (TENGs). Using the characteristic that lipids on leaves regenerate within a few hours, lipids from living tree leaves are collected, and lipid‐based nondestructive TENGs are fabricated. The concept of energy‐harvesting vines is also presented, which can generate electricity when they are wrapped loosely on living tree branches. This study suggests how to harvest electricity while preserving nature as it is.
Design of an Inorganic Mesoporous Hole‐Transporting Layer for Highly Efficient and Stable Inverted Perovskite Solar Cells
Authors: Chen Yu , Yang Zhou , Wang Shubo , Zheng Xiaojia , Wu Yihui , Yuan Ningyi , Zhang Wen‐Hua , Liu Shengzhong (Frank)
Published: November 2018

The unstable feature of the widely employed organic hole‐transporting materials (HTMs) (e.g., spiro‐MeOTAD) significantly limits the practical application of perovskite solar cells (PSCs). Therefore, it is desirable to design new structured PSCs with stable HTMs presenting excellent carrier extraction and transfer properties. This work demonstrates a new inverted PSC configuration. The new PSC has a graded band alignment and bilayered inorganic HTMs (i.e., compact NiOx and mesoporous CuGaO2). In comparison with planar‐structured PSCs, the mesoporous CuGaO2 can effectively extract holes from perovskite due to the increased contact area of the perovskite/HTM. The graded energy alignment constructed in the ultrathin compact NiOx, mesoporous CuGaO2, and perovskite can facilitate carrier transfer and depress charge recombination. As a result, the champion device based on the newly designed mesoscopic PSCs yields a stabilized efficiency of ≈20%, which is considered one of the best results for inverted PSCs with inorganic HTMs. Additionally, the unencapsulated PSC device retains more than 80% of its original efficiency when subjected to thermal aging at 85 °C for 1000 h in a nitrogen atmosphere, thus demonstrating superior thermal stability of the device. This study may pave a new avenue to rational design of highly efficient and stable PSCs.
Pyridine‐Hydrazone Ligands in Asymmetric Palladium‐Catalyzed 1,4‐ and 1,6‐Additions of Arylboronic Acids to Cyclic (Di)enones
Authors: de Gracia Retamosa María , Álvarez‐Casao Yolanda , Matador Esteban , Gómez Ángela , Monge David , Fernández Rosario , Lassaletta José M.
Published: November 2018

Catalysts generated by combinations of Pd(TFA)2 and enantiomerically pure pyridine‐hydrazone ligands have been applied to the 1,4‐addition of arylboronic acids to β‐substituted cyclic enones, building all‐carbon quaternary stereocenters in high yields and enantioselectivities (up to 93% ee). The developed methodology allows the efficient introduction of ortho‐substituted aryl groups in β‐position of cyclopentanone cores, giving scaffolds present in a broad range of biologically active natural products. These Pd(II)‐complexes served also as catalysts in the 1,6‐addition of arylboronic acids to cyclic dienones, affording complete regioselectivities, moderate yields and good enantioselectivities (up to 80% ee).

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Influence of Mesoporous Silica Properties on Cyclic Carbonate Synthesis Catalysed by Supported Aluminium(Salen) Complexes
Authors: Carvalho Patricia A. , Comerford James W. , Lamb Katie J. , North Michael , Reiss Paul S.
Published: November 2018

By modification of pore size and morphology, pore‐expanded variants of SBA‐15 and KIT‐6 have been utilised as mesoporous silica supports for the immobilisation of a bimetallic aluminium‐salen complex. The performance of the resulting heterogeneous catalysts in the synthesis of cyclic carbonates from carbon dioxide and terminal epoxides was assessed. Support materials which retained higher pore volume and surface areas after catalyst immobilisation demonstrated enhanced conversions to the desired cyclic carbonates. This was rationalised to be a consequence of the promotion of reactant mass transport through a less‐inhibited pore structure.

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Electric‐Field Control of Magnetic Order: From FeRh to Topological Antiferromagnetic Spintronics
Authors: Feng Zexin , Yan Han , Liu Zhiqi
Published: November 2018

Using an electric field instead of an electric current (or a magnetic field) to tailor the electronic properties of magnetic materials is promising for realizing ultralow‐energy‐consuming memory devices because of the suppression of Joule heating, especially when the devices are scaled down to the nanoscale. Here, recent results on giant magnetization and resistivity modulation in a metamagnetic intermetallic alloy, FeRh, which is achieved by electric‐field‐controlled magnetic phase transitions in multiferroic heterostructures are summarized. Furthermore, this approach is extended to topological antiferromagnetic spintronics, which is currently receiving attention in the magnetic society. Furthermore, the antiferromagnetic order parameter can switch back and forth via a small electric field. In the end, the possibility of manipulating exotic physical phenomena in the emerging topological antiferromagnetic spintronics field via the electric‐field approach is envisioned.
Kinetic Stability of Bulk LiNiO2 and Surface Degradation by Oxygen Evolution in LiNiO2‐Based Cathode Materials
Authors: Kong Fantai , Liang Chaoping , Wang Luhua , Zheng Yongping , Perananthan Sahila , Longo Roberto C. , Ferraris John P. , Kim Moon , Cho Kyeongjae
Published: November 2018

Capacity degradation by phase changes and oxygen evolution has been the largest obstacle for the ultimate commercialization of high‐capacity LiNiO2‐based cathode materials. The ultimate thermodynamic and kinetic reasons of these limitations are not yet systematically studied, and the fundamental mechanisms are still poorly understood. In this work, both phenomena are studied by density functional theory simulations and validation experiments. It is found that during delithiation of LiNiO2, decreased oxygen reduction induces a strong thermodynamic driving force for oxygen evolution in bulk. However, oxygen evolution is kinetically prohibited in the bulk phase due to a large oxygen migration kinetic barrier (2.4 eV). In contrast, surface regions provide a larger space for oxygen migration leading to facile oxygen evolution. These theoretical results are validated by experimental studies, and the kinetic stability of bulk LiNiO2 is clearly confirmed. Based on these findings, a rational design strategy for protective surface coating is proposed.
Variations in ramet performance and the dynamics of an alpine evergreen herb,Gentiana nipponica, in different snowmelt conditions
Authors: Kawai Yuka , Kudo Gaku
Published: November 2018

Premise of the Study

Variation in demographic parameters reflects the life‐history strategies of plants in response to specific environments. We aimed to investigate the intraspecific variation in life‐history traits of a clonal alpine herb,Gentiana nipponica, in various snowmelt conditions.

Methods

Individual ramets within genets accumulate leaves for 7–9 yr without shedding, and die after reproduction. We tested the physiological function of accumulated leaves for reproduction and monitored the ramet demography in early, intermediate, and late snowmelt populations over 3 yr. Then, we simulated ramet dynamics using the demographic parameters.

Key Results

Old leaves had a carbon storage function, and the initiation of reproduction depended on the amount of ramet leaves. Growth and reproductive performance were highest in the population with an intermediate snowmelt period. The early snowmelt population showed short persistence periods due to restricted growth and high mortality of the ramets. The late snowmelt populations showed slow growth, but high survival rate of the ramets, in which the ramet size at reproduction was smallest and fruit formation was often suppressed by the short growing period.

Conclusions

Limiting factors dictating the distribution ofG. nipponicadiffered between the early and late snowmelt habitats. High mortality and restricted growth, because of the harsh environment, determine the distribution limit toward earlier snowmelt locations. By contrast, late snowmelt strongly limited fecundity because of the short period for fruit maturation. The difference in snowmelt time provides a clear gradient of selective forces that may promote local adaptation among neighboring populations.
Association of prepubertal obesity with pubertal development in Chinese girls and boys: A longitudinal study
Authors: Li Wenyan , Liu Qin , Deng Xu , Chen Yiwen , Yang Bo , Huang Xin , Østbye Truls
Published: November 2018

Objectives

The purpose of this study was to examine the association of prepubertal body mass index (BMI) and weight status with pubertal development in boys and girls in Chongqing, China.

Methods

In a longitudinal study, 1237 students (695 boys and 542 girls) were recruited from Chongqing, China, and examined at baseline, then followed every 6 months for three and a half years. Height, weight, testicular volume, and breast development were measured at every examination. Age of first spermatorrhea and menarche were obtained from self‐report. Subjects were divided into normal weight, overweight, and obese groups according to baseline BMI. Multivariable Cox regression analysis was used to examine the association of BMI and weight status with pubertal development.

Results

In girls, higher prepubertal BMI increased the chance of earlier menarche (hazards ratio (HR): 1.205, 95% confidence interval (95% CI): 1.151‐2.261) and breast development (HR: 1.092, 95% CI: 1.045‐1.142). Girls in the overweight (HR: 2.605, 95% CI: 1.716‐3.956) and obese (HR: 2.565, 95% CI: 1.603‐4.103) groups had an increased risk of early menarche compared with those in the normal weight group, while only overweight was associated with an increased risk for earlier breast development (HR: 1.469, 95% CI: 1.024‐2.108). In boys, higher prepubertal BMI was significantly associated with the timing of first spermatorrhea (HR: 1.054, 95% CI: 1.004‐1.106) and testicular development (HR: 1.098, 95% CI: 1.063‐1.135). Overweight (HR: 1.672, 95% CI: 1.204‐2.322) and obesity (HR: 1.598, 95% CI: 1.135‐2.249) increased the hazard of earlier testicular development compared with the normal weight group, while no significant differences were detected among the three weight groups in terms of time to first spermatorrhea.

Conclusions

Higher prepubertal BMI was associated with earlier puberty in both Chinese boys and girls.
Contrasting Reactivity of 2‐chloro‐1‐formyl‐3‐hydroxymethylenecyclohexene and its Schiff Bases towards Disodium Diselenide: Isolation of Selenospirocycles versus Azapentalenes
Authors: Venkateshwaran Krishnan , Rajesh Prasad Poonam , Deka Rajesh , Raju Saravanan , Singh Harkesh B. , Butcher Ray J.
Published: November 2018

A convenient approach for the synthesis of alicyclic selenospirocycles, 24 and 25, stabilized by intramolecular chalcogen bonding (IChB) is reported by the reaction of 5‐alkyl‐2‐chloro‐1‐formyl‐3‐hydroxymethylenecyclohexene derivatives {alkyl=H (22), Me (23)} with in situ generated disodium diselenide (Na2Se2). However, when 2‐chloro‐1‐formyl‐3‐hydroxymethylenecyclohexene, 22 is condensed with aniline or 4‐methoxyaniline and the resulting Schiff bases 26 and 27 are subjected to identical reactions, the Schiff bases undergo cyclisation to afford brightly colored, fused 1,6‐diaza‐6a‐selenapentalene derivatives 28–29, instead of the expected selenospirocycles. The aromatic nucleophilic substitution (SNAr) reaction of N‐(2‐bromo‐3‐nitrobenzyl)naphthylamine, 33 with nBuSeLi affords N‐[2‐(butylselanyl)‐3‐nitrobenzyl]naphthylamine, 34. The bromination of 34 results in the formation of cyclic isoselenazolines, 35. Selenospirocycles 24 and 25, 1,6‐diaza‐6a‐selenapentalenes 28 and 29 and isoselenazoline 35 are authenticated by single‐crystal X‐ray diffraction studies. Compounds 24, 25 and 35 are stabilized by intramolecular secondary interactions.