bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel rare frameshift variation in aggressive periodontitis: Exomic and familial‐screening analysis
Authors: Taiete Tiago , Casati Marcio Z. , Martins Luciane , Andia Denise C. , Mofatto Luciana S. , Coletta Ricardo D. , Monteiro Mabelle F. , Araújo Cássia F. , Santamaria Mauro P. , Corrêa Mônica G. , Sallum Enilson A. , Nociti Francisco H. , Casarin Renato C.
Published: August 2019

Background

Aggressive periodontitis (AgP), currently periodontitis grade C, presents early onset, rapid progression, and a poorly established genetic association. Thus, this study aimed to identify genetic variants associated with AgP via whole exome sequencing (WES) through a familial screening approach.

Methods

WES was performed in two nuclear families, including a proband and a parent affected by AgP and an unaffected parent and sibling. Common variants among affected individuals, excluding those common to healthy people, from each family, composed the data set associated with AgP. In silico analysis evaluated the impact of each variant on protein structure and protein‐protein interactions. Moreover, identified deleterious variants were validated in a populational analysis (n = 96).

Results

The missense single nucleotide variations (SNVs) rs142548867 in EEFSEC (c.668C>T), rs574301770 in ZNF136 (c.466C>G), and rs72821893 in KRT25 (c.800G>A) and the frameshift indels rs37146475 in GPRC6A (c.2323‐2324insT) and c.1366_1372insGGAGCAG in ELN were identified in AgP and have a predicted functional impact on proteins. In silico analysis indicated that the indel in GPRC6A generates a loss of the C‐terminal tail of the Gprca protein. Furthermore, this SNV was significantly associated with AgP in a population‐based investigation.

Conclusion

Novel frameshift variation in GPRC6A (c.2323‐2324insT) was identified as a potential genetic alteration associated with AgP occurrence.
Non‐cyanobacterial diazotrophs dominate nitrogen‐fixing communities in permafrost thaw ponds
Authors: Fernandez Leyden , Bertilsson Stefan , Peura Sari
Published: August 2019

There is a growing concern about the implications of accelerated thawing of permafrost for regional biogeochemical cycling of carbon and other bioreactive elements. One such element of concern is nitrogen, and in this study, we investigated the diversity and biogeography of potential diazotrophs within a series of thaw ponds representing different ontogenetic stages in pond development. Using metagenomic sequence data from subarctic thaw ponds, we identified an array of nitrogenase genes across the ponds. The iron‐only nitrogenase gene (anfH) was positively correlated with sulfate, while there was no correlation with methane despite previous findings that organisms carrying anfH can simultaneously participate in nitrogen fixation and methanogenesis. Sulfate is known to inhibit microbial uptake of molybdate, an element essential for the activity of the nifH (molybdenum‐iron) nitrogenase and this may explain the high potential for nitrogen fixation utilizing anfH in sulfate‐rich ponds. NifH was particularly abundant in the hypolimnion of the deeper and older ponds, with Deltaproteobacteria and Chlorobi as the putative dominant diazotrophs. In the epilimnetic waters, nifH composition was more variable, with various Gammaproteobacteria as abundant representatives, while cyanobacterial diazotrophs were scarce. Interestingly, nifH gene abundance was significantly positively correlated with in situ methane concentration. Based on genome‐resolved metagenomics, we hypothesize that diazotrophs and methanogens engage in syntrophic interactions in anoxic waters, possibly via propionate oxidation or (in Geobacter) by interspecies electron transfer. Our results also suggest that nitrogen fixers may supply bioreactive nitrogen compounds to the thaw pond communities, thereby enhancing growth and activity of methanogens.
Reconstruction for a class of the inverse transmission eigenvalue problem
Authors: Wang Yu Ping , Zhao Wenju , Shieh Chung Tsun
Published: August 2019

The authors present a constructive algorithm for the numerical solution to a class of the inverse transmission eigenvalue problem. The numerical experiments are provided to demonstrate the efficiency of our algorithms by a numerical example.
Derivation of surface shape for inflatable large aperture antennas
Authors: Welch Bryan W.
Published: August 2019

Large deployable aperture inflatable antennas are an emerging technology that is being investigated for potential use in science and exploration missions. In particular, for missions to Mars and beyond, large deployable aperture antennas can provide the antenna gain required for high data rate communications, where the necessary antenna diameter exceeds the available volume of typical launch vehicle platforms. Previous efforts have found that inflatable large aperture antennas do not follow a parabolic shape, and so the nominal Ruze equation is not applicable due to the macroscopic shape errors that exist in this type of technology. Therefore, geometric evaluations of the surface profile cannot simply correlate root‐mean‐square shape error with a parabolic surface to antenna gain degradation. Consequently, the focus of this work is to derive an accurate mathematical model of an inflatable large aperture antenna so that its performance can be characterized. That derivation activity is described in this paper through the calculus of variations methodology, augmented with experimental test data obtained with a laser radar system to validate the surface profile model predicted.
A graphene‐based tunable negative refractive index metamaterial and its application in dynamic beam‐tilting terahertz antenna
Authors: Luo Yanbin , Zeng Qingsheng , Yan Xin , Jiang Tao , Yang Rongcao , Wang Jiayun , Wu Yong , Lu Qichao , Zhang Xia
Published: August 2019

Graphene is emerging as a kind of promising 2D material in designing reconfigurable terahertz (THz) devices owning to its tunability of the surface conductivity, which can be tuned by changing the chemical potential. In this work, we demonstrated a graphene‐based THz tunable negative refractive index metamaterial. The proposed metamaterial unit consists of a metallic resonant structure and embedded graphene, which presents a dynamic negative refractive index in the corresponding bands by modulating the chemical potential of the embedded graphene. In addition, a dynamic beam‐tilting antenna loaded with the metamaterial‐based stacked configuration has been designed. Through changing the refractive index of the metamaterial or the number of layers in the stacked configuration, the steering angle can be adjusted from 0° to −27°. This work demonstrates the great potential of graphene in THz tunable negative refractive index materials, provides a classic case about the practical application of controllable negative refractive index, and also gives an effective way to design dynamic beam‐tilting antenna.
Determination of 3D PSFs from computed tomography reconstructed x‐ray images of spherical objects and the effects of sphere radii
Authors: Robert Normand , Mainprize James G. , Whyne Cari
Published: August 2019

Purpose

A method was developed to obtain three‐dimensional (3D) point spread functions (PSFs) of reconstructed x‐ray volumetric images using spheres of known diameters. The algorithm consists of a sphere localization step using template matching applied to the entire volume. Richardson Lucy (RL) deconvolution is used atypically to determine the PSF from the reconstructed x‐ray image and a model of the sphere. The resulting PSF is arbitrary, that is, there are no assumptions of separability or symmetry. Oversampling is not used, and sample spacing matches the image. The effect of sphere radius on PSF estimate reproducibility is investigated.

Methods

Phantoms were constructed by suspending five polytetrafluoroethylene (PTFE) spheres having known radii equal to 4.77, 7.95, 9.52, 12.68, and 19.53 mm in an agar solution. The phantom included a 25 μm steel wire to calculate a line spread function (LSF). The phantom was imaged and reconstructed with a Medtronic surgical O‐Arm 23 times and a Toshiba Aquilion One computed tomography (CT) 20 times. A sharp reconstruction kernel exhibiting a nonmonotonic PSF was used with the Toshiba CT. PSFs and LSFs were computed for all of the images and repeated estimates were used to compute mean and standard deviation values for every point of the PSFs and LSFs. The PSFs from spheres were converted to LSFs and compared to the wire LSF.

Results

The standard deviations of the PSF estimates exhibit a decreasing trend as the sphere radius is increased. The PSF from the smallest 4.77 mm sphere is the least reproducible. The normalized root mean square difference between the mean LSF derived from the 4.77 mm radius sphere and the mean wire LSF is 2.0% for the O‐arm and 1.2% for the CT.

Conclusion

Richardson Lucy (RL) deconvolution provides a method to estimate generalized (no separability or other simplifying assumptions) 3D PSFs from spheres. X‐ray noise in images acquired with typical clinical protocols cause noticeable variations in PSF estimates which can be mitigated by selecting larger spheres and combining PSF estimates from different images.
Automated retinal lesion detection via image saliency analysis
Authors: Yan Qifeng , Zhao Yitian , Zheng Yalin , Liu Yonghuai , Zhou Kang , Frangi Alejandro , Liu Jiang
Published: August 2019

Background and objective

The detection of abnormalities such as lesions or leakage from retinal images is an important health informatics task for automated early diagnosis of diabetic and malarial retinopathy or other eye diseases, in order to prevent blindness and common systematic conditions. In this work, we propose a novel retinal lesion detection method by adapting the concepts of saliency.

Methods

Retinal images are first segmented as superpixels, two new saliency feature representations: uniqueness and compactness, are then derived to represent the superpixels. The pixel level saliency is then estimated from these superpixel saliency values via a bilateral filter. These extracted saliency features form a matrix for low‐rank analysis to achieve saliency detection. The precise contour of a lesion is finally extracted from the generated saliency map after removing confounding structures such as blood vessels, the optic disk, and the fovea. The main novelty of this method is that it is an effective tool for detecting different abnormalities at the pixel level from different modalities of retinal images, without the need to tune parameters.

Results

To evaluate its effectiveness, we have applied our method to seven public datasets of diabetic and malarial retinopathy with four different types of lesions: exudate, hemorrhage, microaneurysms, and leakage. The evaluation was undertaken at the pixel level, lesion level, or image level according to ground truth availability in these datasets.

Conclusions

The experimental results show that the proposed method outperforms existing state‐of‐the‐art ones in applicability, effectiveness, and accuracy.
Digital tomosynthesis based digital volume correlation: A clinically viable noninvasive method for direct measurement of intravertebral displacements using images of the human spine under physiological load
Authors: Oravec Daniel , Flynn Michael J. , Zauel Roger , Rao Sudhaker , Yeni Yener N.
Published: August 2019

Purpose

We have developed a clinically viable method for measurement of direct, patient‐specific intravertebral displacements using a novel digital tomosynthesis based digital volume correlation technique. These displacements may be used to calculate vertebral stiffness under loads induced by a patient's body weight; this is particularly significant because, among biomechanical variables, stiffness is the strongest correlate of bone strength. In this proof of concept study, we assessed the feasibility of the method through a preliminary evaluation of the accuracy and precision of the method, identification of a range of physiological load levels for which displacements are measurable, assessment of the relationship of measured displacements with microcomputed tomography based standards, and demonstration of the in vivo application of the technique.

Methods

Five cadaveric T11 vertebrae were allocated to three groups in order to study (a) the optimization of digital volume correlation algorithm input parameters, (b) accuracy and precision of the method and the ability to measure displacements at a range of physiological load levels, and (c) the correlation between displacements measured using tomosynthesis based digital volume correlation vs. high resolution microcomputed tomography based digital volume correlation and large scale finite element models. Tomosynthesis images of one patient (Female, 60 yr old) were used to calculate displacement maps, and in turn stiffness, using images acquired in both standing and standing‐with‐weight (8 kg) configurations.

Results

We found that displacements were accurate (2.28 µm total error) and measurable at physiological load levels (above 267 N) with a linear response to applied load. Calculated stiffness among three tested vertebral bodies was within an acceptable range relative to reported values for vertebral stiffness (5651‐13260 N/mm). Displacements were in good qualitative and quantitative agreement with both microcomputed tomography based finite element (r2 = 0.762, P < 0.001) and digital volume correlation (r2 = 0.799, P < 0.001) solutions. For one patient tested twice, once standing and once holding weights, results demonstrated excellent qualitative reproducibility of displacement distributions with superior endplate displacements increasing by 22% with added weight.

Conclusions

The results of this work collectively suggest the feasibility of the method for in vivo measurement of intravertebral displacements and stiffness in humans. These findings suggest that digital volume correlation using digital tomosynthesis imaging may be useful in understanding the mechanical response of bone to disease and may further enhance our ability to assess fracture risk and treatment efficacy for the spine.
Predicting Persistence of Rio Grande Cutthroat Trout Populations in an Uncertain Future
Authors: Zeigler Matthew P. , Rogers Kevin B. , Roberts James J. , Todd Andrew S. , Fausch Kurt D.
Published: August 2019

The Rio Grande Cutthroat Trout Oncorhynchus clarkii virginalis (RGCT) occupies just 12% of its ancestral range. As the southernmost subspecies of Cutthroat Trout, we expect a warming climate to bring additional stressors to RGCT populations, such as increased stream temperatures, reduced streamflows, and increased incidence of wildfire. We developed a Bayesian network (BN) model using site-specific data, empirical research, and expert knowledge to estimate the probability of persistence for each of the 121 remaining RGCT conservation populations and to rank the severity of the threats they face. These inputs quantified the genetic risks (e.g., inbreeding risk and hybridization risk), population demographics (disease risk, habitat suitability, and survival), and probability of stochastic disturbances (stream drying risk and wildfire risk) in an uncertain future. We also created stream temperature and base flow discharge models coupled with regionally downscaled climate projections to predict future abiotic conditions at short-term (2040s) and long-term (2080s) time horizons. In the absence of active management, we predicted a decrease in the average probability of population persistence from 0.53 (current) to 0.31 (2040s) and 0.26 (2080s). Only 11% of these populations were predicted to have a greater than 75% chance of persisting to the 2080s. Threat of invasion by nonnative trout had the strongest effect on population persistence. Of the 78 populations that are already invaded or lacking complete barriers, 60% were estimated to be extirpated by 2080 and the remainder averaged only a 10% chance of persistence. In contrast, the effects of increased stream temperatures were predicted to affect the future persistence of only 9% of the 121 RGCT populations remaining, as most have been restricted to high-elevation habitats that are cold enough to buffer against some stream warming. Our BN model provides a framework for evaluating threats and will be useful to guide management actions that are likely to provide the most benefit for long-term conservation.
Identification of guinea pig remains in the Pucará de Tilcara (Jujuy, Argentina): Evidence in favour of the presence of the Andean breed in the Quebrada de Humahuaca
Authors: Lopez Geronazzo Lautaro N. , Otero Clarisa , Álvarez Alicia , Ercoli Marcos D. , Cortés‐Delgado Natalia
Published: August 2019

In this article, we identified rodent remains found in the Pucará de Tilcara, an archaeological site from the Argentine Northwest that was occupied by humans from 1,100 aduntil the Spanish conquest. The zooarchaeological analyses were carried out using anatomical descriptions and geometric morphometric analyses of the dorsal and ventral views of mandibular remains. The results and the archaeological context discussed showed that all the rodent remains could correspond to the Andean breed of domestic guinea pigs. The combination of the methods used here gave us a strong support to the taxonomical assignment. The presence of domestic guinea pigs in archaeological sites of the northwestern Argentina was never proposed. This approach allowed us to increase knowledge about the distribution of caviines in the region, and their relationship to anthropic processes.
Pipeline Rehab: Consider Best Practices for Coating Above‐Grade Steel Water Lines
Authors: Kirby Christine , Price Venus
Published: August 2019

When facing the unique challenge of coating active water lines, Houston Public Works learned that planning, execution, and teamwork are the keys to success.
Tailoring block copolymer nanoporous thin films with acetic acid as a small guest molecule
Authors: Alvarez‐Fernandez Alberto , Valdes‐Vango Fernando , Martín José Ignacio , Vélez María , Quirós Carlos , Hermida‐Merino Daniel , Portale Giuseppe , Alameda José María , García Alonso Francisco Javier
Published: August 2019

Block copolymers offer the fabrication of mesoporous thin films with distinct nanoscale structural features. In this contribution, we present the use of acetic acid (CH3COOH) as a low‐molecular‐weight guest molecule to tune the supramolecular assembly of poly[styrene‐block‐(4‐vinylpyridine)] (PS‐b‐P4VP), offering a versatile and straightforward method to obtain tailored nanostructured films with controlled topography and pore size. Spin‐coating toluene solutions of PS‐b‐P4VP, with a variable amount of CH3COOH, leads to micellar thin films, where the micelles contain the carboxylic acid as a guest molecule. The size can be conveniently modified in these films (from 48 to 75 nm) by varying the amount of organic acid in the starting solutions. Subsequent surface reconstruction of micellar films using ethanol leads to ring‐shaped copolymer nanoporous films with modulated diameter. Controlling the micelle reconstruction process, cylindrical porous films are also obtained. Interestingly, changing the type of aliphatic carboxylic acid leads to a modification of the observed film morphology from micelles to out‐of‐plane P4VP cylinders (or lamellae) in a PS matrix. © 2019 Society of Chemical Industry
Towards new environmentally friendly fluoroelastomers: from facile chemical degradation to efficient photo‐crosslinkable reaction
Authors: Wang Yu , Liu Huihui , Zheng Xiaoqiang , Bai Yongping
Published: August 2019

Our objective is to develop a versatile and facile method that allows the synthesis of novel primary fluorinated co‐oligomers as precursors of photo‐crosslinkable networks. Transparent carboxyl‐terminated fluorinated co‐oligomers with molecular weights ranging between 2000 and 10 400 g mol−1 were synthesized via facile degradation. The structural changes of fluorinated backbone were investigated using various analysis techniques. Then two major approaches, namely esterification and ring opening, were applied to obtain photochemical diacrylates (HEMA‐ and GMA‐IEM‐terminated co‐oligomers). These two precursors can be cured in 60 s under UV radiation without high temperature, high pressure or toxic solvent. The glass transition temperatures of HEMA‐ and GMA‐IEM‐terminated fluoropolymers at about −20 °C, assessed from differential scanning calorimetry, showed an increase after crosslinking, and the glass transitions at 20 °C were no longer observed. These two crosslinked films were found to have higher decomposition temperatures, when compared to starting precursors. The contact angles on the surface of the two elastomer materials were only about 74° and 78°, which increased to 105° and 110° after UV irradiation. The tensile strength of the two cured fluoroelastomers can still reach 1.3 MPa at 200 °C. © 2019 Society of Chemical Industry
Specificity of Acyl Chain Composition of Phosphatidylinositols
Authors: Bozelli José Carlos , Epand Richard M.
Published: August 2019

Phosphatidylinositol (PI) lipids have a predominance of a single molecular species present through the organism. In healthy mammals this molecular species is 1‐stearoyl‐2‐arachidonoyl (18:0/20:4) PI. Although the importance of PI lipids for cell physiology has long been appreciated, less is known about the biological role of enriching PI lipids with 18:0/20:4 acyl chains. In conditions with dysfunctional lipid metabolism, the predominance of 18:0/20:4 acyl chains is lost. Recently, molecular mechanisms underpinning the enrichment or alteration of these acyl chains in PI lipids have begun to emerge. In the majority of the cases a common feature is the presence of enzymes bearing substrate acyl chain specificity. However, in cancer cells, it has been shown that one (not the only) of the mechanisms responsible for the loss in this acyl chain enrichment is mutation on the transcription factor p53 gene, which is one of the most highly mutated genes in cancers. There is a compelling need for a global picture of the specificity of the acyl chain composition of PIs. This can be possible once high‐resolution spatio‐temporal information is gathered in a cellular context; which can ultimately lead to potential novel targets to combat conditions with altered PI acyl chain profiles.
On the formation of nanocapsules in aerosol‐assisted atmospheric‐pressure plasma
Authors: Lo Porto Chiara , Palumbo Fabio , Fracassi Francesco , Barucca Gianni , Favia Pietro
Published: August 2019

Aerosol‐assisted atmospheric‐pressure plasma can lead to the deposition of very appealing core‐shell structured nanocapsules. In this work, the aerosol solution composition has been changed in terms of solute nature and concentration in order to better understand the nanocapsule formation and structure. In particular, electron microscopy techniques and microanalysis characterization have been carried out to provide a rationale for such one‐step deposition of nanocapsules in plasma. A possible mechanism for the formation of the nanocapsules is suggested, based on the current theories on droplet evaporation in atomization processing, and on the implications of the coupling of aerosol with plasma environment.
Origin of Antibacterial Activity of ZnO Nanoparticles: The Roles of Protonic and Electronic Conductions
Authors: Kim Hye Ri , Lee Daae , Lee Ga Hyeon , Kim Seong Kyun , Choi Seong Jin , Hwang Ee Taek , Maharjan Anoth , Kim Beom Soo , Kim Dongyoung , Joo Jong Hoon
Published: August 2019

To elucidate the origin of antibacterial activity of ZnO nanoparticles, a reactive oxygen species (ROS) mechanism is systematically investigated based on electronic and protonic conductions. While the enhancement of antibacterial activity by an increase in electronic conductivity is marginal, an apparent improvement is observed by in the increase of protonic conductivity in terms of the surface basicity. This study first demonstrates that antibacterial activity can be enhanced by controlling the surface basicity of solid particles. The basicity of ZnO can be modulated by doping alkaline‐earth oxides such as MgO and CaO, and it results in the increase of hydroxyl defects on the surface of solid particles. The basicity shows a strong dependency on mobile OH concentrations. The increase of ROS hydroxyl radicals is confirmed by Mg (ZMO) or Ca‐doping (ZCO), which shows high antibacterial activity, and Ca‐doped ZnO exhibits the highest performance. It is clearly observed that the antibacterial activity is proportional to the basicity, which is controlled by the mobile OH formation. While both electrons and hydroxyl species are required for ROS reactions, it is concluded that the formation of hydroxyl species is a key factor in improving the antibacterial activity in ZnO.
Lock‐In Thermography to Analyze Plasmonic Nanoparticle Dispersions
Authors: Steinmetz Lukas , Taladriz‐Blanco Patricia , Geers Christoph , Spuch‐Calvar Miguel , Bonmarin Mathias , Balog Sandor , Rothen‐Rutishauser Barbara , Petri‐Fink Alke
Published: August 2019

The physicochemical properties of nanoparticles (NPs) strongly rely on their colloidal stability, and any given dispersion can display remarkably different features, depending on whether it contains single particles or clusters. Thus, developing efficient experimental methods that are able to provide accurate and reproducible measures of the NP properties is a considerable challenge for both research and industrial development. By analyzing different NPs, through size and concentration, it is demonstrated that lock‐in thermography, based on light absorption and heat generation, is able to detect and differentiate the distinct aggregation and re‐dispersion behavior of plasmonic NPs, e.g., gold and silver. Most importantly, the approach is nonintrusive and potentially highly cost‐effective compared to standard analytical techniques.
Long‐Term Colloidal and Chemical Stability in Aqueous Media of NaYF4‐Type Upconversion Nanoparticles Modified by Ligand‐Exchange
Authors: Himmelstoß Sandy F. , Hirsch Thomas
Published: August 2019

Surface capping is an essential component of nanoparticles as it provides access to their outstanding properties in the real world. Upconversion nanoparticles are predominantly interesting for use in biological environments, due to their excellent optical properties such as the conversion of near‐infrared excitation light into emissions in the visible or UV range of the spectrum, high photostability, and the absence of any intermittence. One of the most efficient upconversion nanoparticles, consisting of lanthanide doped NaYF4, suffers from limited stability in aqueous media. This study investigates a set of five types of surface coatings, ranging from small ligands to polymers of different charge and different coordinating groups, on monodisperse 28 ± 0.9 nm sized NaYF4(Yb,Er) nanoparticles modified by a two‐step ligand exchange mediated by NOBF4. Information on the long‐term chemical and colloidal stability for highly diluted aqueous dispersions of these particles is acquired by transmission electron microscopy, dynamic light scattering, and luminescence spectroscopy. The findings are of importance for the development of probes and labels based on upconversion nanoparticles for biological applications.
Ionization efficiency ladders as tools for choosing ionization mode and solvent in liquid chromatography/mass spectrometry
Authors: Rebane Riin , Kruve Anneli , Liigand Jaanus , Liigand Piia , Gornischeff Artur , Leito Ivo
Published: August 2019

Rationale

The choice of mobile phase components and optimal ion source, mainly electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI), is a crucial part in liquid chromatography/mass spectrometry (LC/MS) method development to achieve higher sensitivity and lower detection limits. In this study we demonstrate how to rigorously solve these questions by using ionization efficiency scales.

Methods

Four ionization efficiency scales are used: recorded with both APCI and ESI sources and using both methanol‐ and acetonitrile‐containing mobile phases. Each scale contains altogether more than 50 compounds. In addition, measurements with a chromatographic column were also performed.

Results

We observed a correlation between calibration graph slopes under LC conditions and logIE values in ESI (but not APCI) thereby validating the use of logIE values for choosing the ion source. Most of the studied compounds preferred ESI as an ion source and methanol as mobile organic phase. APCI remains the ion source of choice for polycyclic aromatic hydrocarbons. For APCI, both acetonitrile and methanol provide similar ionization efficiencies with few exceptions.

Conclusions

Overall the results of this work give a concise guideline for practitioners in choosing an ion source for LC/MS analysis on the basis of the chemical nature of the analytes.
Molecular Programming of Biodegradable Nanoworms via Ionically Induced Morphology Switch toward Asymmetric Therapeutic Carriers
Authors: Cao Shoupeng , Shao Jingxin , Xia Yifeng , Che Hailong , Zhong Zhiyuan , Meng Fenghua , van Hest Jan C. M. , Abdelmohsen Loai K. E. A. , Williams David S.
Published: August 2019

Engineering biodegradable nanostructures with precise morphological characteristics is a key objective in nanomedicine. In particular, asymmetric (i.e., nonspherical) nanoparticles are desirable due to the advantageous effects of shape in a biomedical context. Using molecular engineering, it is possible to program unique morphological features into the self‐assembly of block copolymers (BCPs). However, the criteria of biocompatibility and scalability limit progress due to the prevalence of nondegradable components and the use of toxic solvents during fabrication. To address this shortfall, a robust strategy for the fabrication of morphologically asymmetric nanoworms, comprising biodegradable BCPs, has been developed. Modular BCPs comprising poly (ethylene glycol)‐block‐poly(caprolactone‐gradient‐trimethylene carbonate) (PEG−PCLgTMC), with a terminal chain of quaternary ammonium‐TMC (PTMC‐Q), undergo self‐assembly via direct hydration into well‐defined nanostructures. By controlling the solution ionic strength during hydration, particle morphology switches from spherical micelles to nanoworms (of varying aspect ratio). This ionically‐induced switch is driven by modulation of chain packing with salts screening interchain repulsions, leading to micelle elongation. Nanoworms can be loaded with cytotoxic cargo (e.g., doxorubicin) at high efficiency, preferentially interact with cancer cells, and increase tumor penetration. This work showcases the ability to program assembly of BCPs and the potential of asymmetric nanosystems in anticancer drug delivery.
Ionic‐Activated Chemiresistive Gas Sensors for Room‐Temperature Operation
Authors: Song Young Geun , Shim Young‐Seok , Suh Jun Min , Noh Myoung‐Sub , Kim Gwang Su , Choi Kyoung Soon , Jeong Beomgyun , Kim Sangtae , Jang Ho Won , Ju Byeong‐Kwon , Kang Chong‐Yun
Published: August 2019

The development of high performance gas sensors that operate at room temperature has attracted considerable attention. Unfortunately, the conventional mechanism of chemiresistive sensors is restricted at room temperature by insufficient reaction energy with target molecules. Herein, novel strategy for room temperature gas sensors is reported using an ionic‐activated sensing mechanism. The investigation reveals that a hydroxide layer is developed by the applied voltages on the SnO2 surface in the presence of humidity, leading to increased electrical conductivity. Surprisingly, the experimental results indicate ideal sensing behavior at room temperature for NO2 detection with sub‐parts‐per‐trillion (132.3 ppt) detection and fast recovery (25.7 s) to 5 ppm NO2 under humid conditions. The ionic‐activated sensing mechanism is proposed as a cascade process involving the formation of ionic conduction, reaction with a target gas, and demonstrates the novelty of the approach. It is believed that the results presented will open new pathways as a promising method for room temperature gas sensors.
A 3D‐Structured Sustainable Solar‐Driven Steam Generator Using Super‐Black Nylon Flocking Materials
Authors: Tu Ce , Cai Wenfu , Chen Xue , Ouyang Xiaolong , Zhang Hui , Zhang Zhong
Published: August 2019

Solar‐driven evaporation is a promising way of using abundant solar energy for desalinating polluted water or seawater, which addresses the challenge of global fresh water scarcity. Cost‐effectiveness and durability are key factors for practical solar‐driven evaporation technology. The present cutting‐edge techniques mostly rely on costly and complex fabricated nanomaterials, such as metallic nanoparticles, nanotubes, nanoporous hydrogels, graphene, and graphene derivatives. Herein, a black nylon fiber (BNF) flocking board with a vertically aligned array prepared via a convenient electrostatic flocking technique is reported, presenting an extremely high solar absorbance (99.6%), a water self‐supply capability, and a unique salt self‐dissolution capability for seawater desalination. Through a carefully designed 3D structure, a plug‐in‐type BNF flocking board steam generator realizes a high evaporation rate of 2.09 kg m−2 h−1 under 1 kW m−2 solar illumination, well beyond its corresponding upper limit of 1.50 kg m−2 h−1 (assuming 100% solar energy is being used for evaporation latent heat). With the advantages of high‐efficiency fabrication, cost‐effectiveness, high evaporation rate, and high endurance in seawater desalination, this 3D design provides a new strategy to build up an economic, sustainable, and rapid solar‐driven steam generation system.
Compactly Coupled Nitrogen‐Doped Carbon Nanosheets/Molybdenum Phosphide Nanocrystal Hollow Nanospheres as Polysulfide Reservoirs for High‐Performance Lithium–Sulfur Chemistry
Authors: Sun Zhonghui , Wu Xing‐Long , Peng Zhangquan , Wang Jiawei , Gan Shiyu , Zhang Yuwei , Han Dongxue , Niu Li
Published: August 2019

Lithium–sulfur (Li–S) batteries have been disclosed as one of the most promising energy storage systems. However, the low utilization of sulfur, the detrimental shuttling behavior of polysulfides, and the sluggish kinetics in electrochemical processes, severely impede their application. Herein, 3D hierarchical nitrogen‐doped carbon nanosheets/molybdenum phosphide nanocrystal hollow nanospheres (MoP@C/N HCSs) are introduced to Li–S batteries via decorating commercial separators to inhibit polysulfides diffusion. It acts not only as a polysulfides immobilizer to provide strong physical trapping and chemical anchoring toward polysulfides, but also as an electrocatalyst to accelerate the kinetics of the polysulfides redox reaction, and to lower the Li2S nucleation/dissolution interfacial energy barrier and self‐discharge capacity loss in working Li–S batteries, simultaneously. As a result, the Li–S batteries with MoP@C/N HCS‐modified separators show superior rate capability (920 mAh g−1 at 2 C) and stable cycling life with only 0.04% capacity decay per cycle over 500 cycles at 1 C with nearly 100% Coulombic efficiency. Furthermore, the Li–S battery can achieve a high area capacity of 5.1 mAh cm−2 with satisfied capacity retention when the cathode loading reaches 5.5 mg cm−2. This work offers a brand new guidance for rational separator design into the energy chemistry of high‐stable Li–S batteries.
The Nanoassembly of an Intrinsically Cytotoxic Near‐Infrared Dye for Multifunctionally Synergistic Theranostics
Authors: Xiao Ya‐Fang , An Fei‐Fei , Chen Jia‐Xiong , Yu Jia , Tao Wen‐Wen , Yu Zhiqiang , Ting Richard , Lee Chun‐Sing , Zhang Xiao‐Hong
Published: August 2019

The combination of diagnostic and therapeutic functions in a single theranostic nanoagent generally requires the integration of multi‐ingredients. Herein, a cytotoxic near‐infrared (NIR) dye (IR‐797) and its nanoassembly are reported for multifunctional cancer theranostics. The hydrophobic IR‐797 molecules are self‐assembled into nanoparticles, which are further modified with an amphiphilic polymer (C18PMH‐PEG5000) on the surface. The prepared PEG‐IR‐797 nanoparticles (PEG‐IR‐797 NPs) possess inherent cytotoxicity from the IR‐797 dye and work as a chemotherapeutic drug which induces apoptosis of cancer cells. The IR‐797 NPs are found to have an ultrahigh mass extinction coefficient (444.3 L g−1 cm−1 at 797 nm and 385.9 L g−1 cm−1 at 808 nm) beyond all reported organic nanomaterials (<40 L g−1 cm−1) for superior photothermal therapy (PTT). In addition, IR‐797 shows some aggregation‐induced‐emission (AIE) properties. Combining the merits of good NIR absorption, high photothermal energy conversion efficiency, and AIE, makes the PEG‐IR‐797 NPs useful for multimodal NIR AIE fluorescence, photoacoustic, and thermal imaging‐guided therapy. The research exhibits the possibility of using a single ingredient and entity to perform multimodal NIR fluorescence, photoacoustic, and thermal imaging‐guided chemo‐/photothermal combination therapy, which may trigger wide interest from the fields of nanomedicine and medicinal chemistry to explore multifunctional theranostic organic molecules.
Herpes Simplex Virus Type-1 Infection Impairs Adult Hippocampal Neurogenesis via Amyloid-β Protein Accumulation
Authors: Li Puma Domenica Donatella , Piacentini Roberto , Leone Lucia , Gironi Katia , Marcocci Maria Elena , De Chiara Giovanna , Palamara Anna Teresa , Grassi Claudio
Published: August 2019

We previously reported that Herpes simplex virus type-1 (HSV-1) infection of cultured neurons triggered intracellular accumulation of amyloid-β protein (Aβ) markedly impinging on neuronal functions. Here, we demonstrated that HSV-1 affects in vitro and in vivo adult hippocampal neurogenesis by reducing neural stem/progenitor cell (NSC) proliferation and their neuronal differentiation via intracellular Aβ accumulation. Specifically, cultured NSCs were more permissive for HSV-1 replication than mature neurons and, once infected, they exhibited reduced proliferation (assessed by 5′-bromo-deoxyuridine incorporation, Ki67 immunoreactivity, and Sox2 mRNA expression) and impaired neuronal differentiation in favor of glial phenotype (evaluated by immunoreactivity for the neuronal marker MAP2, the glial marker glial fibrillary astrocyte protein, and the expression of the proneuronal genes Mash1 and NeuroD1). Similarly, impaired adult neurogenesis was observed in the subgranular zone of hippocampal dentate gyrus of an in vivo model of recurrent HSV-1 infections, that we recently set up and characterized, with respect to mock-infected mice. The effects of HSV-1 on neurogenesis did not depend on cell death and were due to Aβ accumulation in infected NSCs. Indeed, they were: (a) reverted, in vitro, by the presence of either β/γ-secretase inhibitors preventing Aβ production or the specific 4G8 antibody counteracting the action of intracellular Aβ; (b) not detectable, in vivo, in HSV-1-infected amyloid precursor protein knockout mice, unable to produce and accumulate Aβ. Given the critical role played by adult neurogenesis in hippocampal-dependent memory and learning, our results suggest that multiple virus reactivations in the brain may contribute to Alzheimer's disease phenotype by also targeting NSCs. Stem Cells  2019;37:1467–1480
Hybrid discrete‐continuum solvation methods
Authors: Pliego Josefredo R. , Riveros Jose M.
Published: August 2019

Hybrid discrete‐continuum approaches for solvation have been widely applied for diverse problems in chemistry suck as pKa calculation in aqueous and nonaqueous solvents, activation free energy barriers for ionic processes in solution, and surface reactions. A special version of this approach, the cluster‐continuum quasichemical model, has also been used for establishing a single‐ion solvation free energy scale in different solvents compatible with the tetraphenylarsonium tetraphenylborate assumption. The use of discrete‐continuum solvation methods can lead to meaningful improvement with respect to pure continuum solvation models for modeling diverse chemical process in solution. In the case of pKa calculations, there are cases where the root mean squared error is as large as 7 pKa units with pure continuum solvation model and becomes around 1 pKa unit with the hybrid approach. For complex reactions in solution, errors as large as 10 kcal/mol for activation free energies with the pure continuum approach can be substantially reduced with the inclusion of explicit solvent molecules. A discussion of the theory of hybrid discrete‐continuum methods is also presented and further development is expected in the coming years.

This article is categorized under:

Structure and Mechanism > Reaction Mechanisms and Catalysis

Software > Quantum Chemistry

Molecular and Statistical Mechanics > Free Energy Methods
Learning Curve in Laparoscopic Liver Resection, Educational Value of Simulation and Training Programmes: A Systematic Review
Authors: Guilbaud Théophile , Birnbaum David Jérémie , Berdah Stéphane , Farges Olivier , Beyer Berjot Laura
Published: August 2019

Background

The laparoscopic approach is widely accepted as the procedure of choice for abdominal surgery. However, laparoscopic liver resection (LLR) has advanced slowly due to the significant learning curve (LC), and only few publications have dealt with advanced training in LLR.

Methods

Two reviewers conducted systematic research through MEDLINE and EMBASE with combinations of the following keywords: (learning curve OR teaching OR training OR simulation OR education) AND (liver OR hepatic) AND (laparoscopic OR laparoscopy). Robotic‐assisted, hand‐assisted and hybrid LLRs were excluded.

Results

Nineteen studies were retrieved. Overall, the level of evidence was low. Thirteen articles assessed the LC during real‐life LLR, and six articles focussed on simulation and training programmes in LLR. The LC in minor LLR comprised 60 cases overall, and 15 cases for standardised left lateral sectionectomy. For major LLR (MLLR), the LC was 50 cases for most studies, but was reported to be 15–20 cases in more recent studies, provided MLLR is performed progressively in selected patients. However, there was heterogeneity in the literature regarding the number of minor LLRs required before MLLR, with 60 minor LLRs reported as the minimum. Six studies showed a potential benefit of simulation and training programmes in this field. The gradual implementation of LLR combined with simulation‐based training programmes could reduce the clinical impact of LC.

Conclusions

The LC in LLR is a long process, and MLLR should be gradually implemented under the supervision of experienced surgeons. Training outside the operating room may reduce the LC in real‐life situations.
Global Surgery: A 30‐Year Bibliometric Analysis (1987–2017)
Authors: Sgrò Alessandro , Al‐Busaidi Ibrahim S. , Wells Cameron I. , Vervoort Dominique , Venturini Sara , Farina Valeria , Figà Federica , Azkarate Francesc , Harrison Ewen M. , Pata Francesco
Published: August 2019

Introduction

There has been a growing interest in addressing the surgical disease burden in low‐ and middle‐income countries (LMICs). Assessing the current state of global surgery research activity is an important step in identifying gaps in knowledge and directing research efforts towards important unaddressed issues. The aim of this bibliometric analysis was to identify trends in the publication of global surgical research over the last 30 years.

Methods

Scopus® was searched for global surgical publications (1987–2017). Results were hand‐screened, and data were collected for included articles. Bibliometric data were extracted from Scopus® and Journal Citation Reports. Country‐level economic and population data were obtained from the World Bank. Descriptive statistics were used to summarise data and identify significant trends.

Results

A total of 1623 articles were identified. The volume of scientific production on global surgery increased from 14 publications in 1987 to 149 in 2017. Similarly, the number of articles published open access increased from four in 1987 to 68 in 2017. Observational studies accounted for 88.7% of the included studies. The three most common specialties were obstetrics and gynaecology 260 (16.0%), general surgery 256 (15.8%), and paediatric surgery 196 (12.1%). Over two times as many authors were affiliated to an LMIC institution than to a high‐income country (HIC) institution (6628, 71.5% vs 2481, 28.5%, P < 0.001). A total of 965 studies (59.5%) were conducted entirely by LMIC authors, and 534 (32.9%) by collaborations between HICs and LMICs.

Conclusion

The quantity of research in global surgery has substantially increased over the past 30 years. Authors from LMICs seemed the most proactive in addressing the global surgical disease burden. Increasing the funding for interventional studies, and therefore the quality of evidence in surgery, has the potential for greater impact for patients in LMICs.
The Importance of Nutrient Management for Potato Production Part II: Plant Nutrition and Tuber Quality
Authors: Naumann Marcel , Koch Mirjam , Thiel Heike , Gransee Andreas , Pawelzik Elke
Published: August 2019

The term ‘quality’ is a complex parameter in the field of potato production, and the desired quality traits depend on the intended use. Important internal quality traits for potatoes are tuber flesh discolouration, dry matter, and starch content. External quality traits include tuber size and shape as well as resistance against mechanical stress during and after harvest. These quality traits are closely interrelated and genetically controlled. It has been demonstrated that all these parameters are also linked to the nutrient status of the plant and/or the tubers. For instance, the susceptibility of tubers for discolouration of both fresh market and processed cultivars is closely related not only to the nutrient supply but also to post-harvest treatment. Besides, the potential to form carcinogenic compounds like acrylamide from precursors during the deep-frying of potato products and the accumulation of toxic substances like glycoalkaloids are important quality criteria in terms of food safety. The influence of the supply of nutrients on potato tuber quality depends initially on their physiological functions, but the ratio to other nutrient needs should also be taken into account.
The Importance of Nutrient Management for Potato Production Part I: Plant Nutrition and Yield
Authors: Koch Mirjam , Naumann Marcel , Pawelzik Elke , Gransee Andreas , Thiel Heike
Published: August 2019

As part of a successful agronomic strategy, adequate nutrient management of the potato crop is essential throughout the whole growth period. In this review, the importance of balanced fertilisation for potato yield formation and yield security is addressed by taking advantage of the results of field trials and existing literature. The most important roles of the macronutrients nitrogen, phosphorous, potassium, magnesium, calcium and sulphur in the plant and their importance for yield formation in potato are reviewed. Fertilisation practices in potato production are discussed. Due to their various functions in plant metabolism, the impact of plant nutrients on potato yield is complex. Therefore, interactions with abiotic and biotic factors, for instance interactions between two different plant nutrients in the soil and the plant, are taken into account.
The large N limit of OPEs in symmetric orbifold CFTs with $$ \mathcal{N} $$ = (4, 4) supersymmetry
Authors: de Beer Thomas , Burrington Benjamin A. , Jardine Ian T. , Peet A.W.
Published: August 2019

Abstract

We explore the OPE of certain twist operators in symmetric product (S

N
) orbifold CFTs, extending our previous work [1] to the case of

$$ \mathcal{N} $$

N

= (4, 4) supersymmetry. We consider a class of twist operators related to the chiral primaries by spectral flow parallel to the twist. We conjecture that at large N, the OPE of two such operators contains only fields in this class, along with excitations by fractional modes of the superconformal currents. We provide evidence for this by studying the coincidence limits of two 4-point functions to several non-trivial orders. We show how the fractional excitations of the twist operators in our restricted class fully reproduce the crossing channels appearing in the coincidence limits of the 4-point functions.