bluuebunny/crossref_metadata_2025 huggingface dataset:
Bidirectional reconfiguration and thermal tuning of microcantilever metamaterial device operating from 77 K to 400 K
Authors: Pitchappa Prakash , Manjappa Manukumara , Krishnamoorthy Harish N. S. , Chang Yuhua , Lee Chengkuo , Singh Ranjan
Published: December 2017

We experimentally report the bidirectional reconfiguration of an out-of-plane deformable microcantilever based metamaterial for advanced and dynamic manipulation of terahertz waves. The microcantilever is made of a bimaterial stack with a large difference in the coefficient of thermal expansion of the constituent materials. This allows for the continuous deformation of microcantilevers in upward or downward direction in response to positive or negative temperature gradient, respectively. The fundamental resonance frequency of the fabricated microcantilever metamaterial is measured at 0.4 THz at room temperature of 293 K. With decreasing temperature, the resonance frequency continuously blue shifts by 30 GHz at 77 K. On the other hand, with increasing temperature, the resonance frequency gradually red shifts by 80 GHz and saturates at 0.32 THz for 400 K. Furthermore, as the temperature is increased above room temperature, which results in the downward actuation of the microcantilever, a significant resonance line-narrowing with an enhanced quality factor is observed due to tight field confinement in the metamaterial structure. The thermal control of the microcantilever possesses numerous inherent advantages such as enhanced tunable range (∼37.5% in this work compared to previously reported microcantilever metamaterials), continuous tunability, and repeatable operations. The microcantilever metamaterial also shows high robustness to operate at cryogenic conditions and hence opens up the possibility of using meta-devices in harsh environments such as space, polar, and deep sea applications.
Luminescence of defects in the structural transformation of layered tin dichalcogenides
Authors: Sutter P. , Komsa H.-P. , Krasheninnikov A. V. , Huang Y. , Sutter E.
Published: December 2017

Layered tin sulfide semiconductors are both of fundamental interest and attractive for energy conversion applications. Sn sulfides crystallize in several stable bulk phases with different Sn:S ratios (SnS2, Sn2S3, and SnS), which can transform into phases with a lower sulfur concentration by introduction of sulfur vacancies (VS). How this complex behavior affects the optoelectronic properties remains largely unknown but is of key importance for understanding light-matter interactions in this family of layered materials. Here, we use the capability to induce VS and drive a transformation between few-layer SnS2 and SnS by electron beam irradiation, combined with in-situ cathodoluminescence spectroscopy and ab-initio calculations to probe the role of defects in the luminescence of these materials. In addition to the characteristic band-edge emission of the endpoint structures, our results show emerging luminescence features accompanying the SnS2 to SnS transformation. Comparison with calculations indicates that the most prominent emission in SnS2 with sulfur vacancies is not due to luminescence from a defect level but involves recombination of excitons bound to neutral VS in SnS2. These findings provide insight into the intrinsic and defect-related optoelectronic properties of Sn chalcogenide semiconductors.
Effect of phase composition on crystal texture formation in hot deformed nanocrystalline SmCo5 magnets
Authors: Ma Qiang , Yue Ming , Xu Xiaochang , Zhang Hongguo , Zhang Dongtao , Zhang Xuefeng , Zhang Jiuxing
Published: December 2017

In the present study, bulk anisotropic nanocrystalline SmCo5 magnets were prepared by hot press and subsequent hot deformation method. Effect of phase composition on texture and magnetic properties are presented, based on which the mechanism of plastic deformation and texture formation during the hot deformation process is discussed. The SmCo5 magnets were prepared by hot deformation, excessive Sm of 2.5 wt% and 10 wt% was added to compensate the weight loss due to Sm evaporation. Our analyses reveal that the phase composition is one of the most important parameters that determine the texture of SmCo5 magnets. It is therefore suggested that the existence of 2:17 phase and its phase transformation undermined the crystal texture formation as well as the magnetic properties of nanocrystalline SmCo5 magnets.
First-principles study on the magnetic properties of ordered Nd6(Fe,Ga)14 alloys
Authors: Hyodo Kazushige , Toga Yuta , Sakuma Akimasa
Published: December 2017

We studied the stable magnetic structure of ordered Nd6Fe14-xGax (x = 0, 1) alloys, which appears in the grain-boundary phase of Nd-Fe-B permanent magnets, using first-principles techniques. Slight Ga doping (x = 1) was shown to contribute to the stabilization of an anti-ferromagnetic (AF) state, whereas the non-doped case (x = 0) was revealed to favor the ferromagnetic state rather than the AF state with a slight energy difference.
Directed aggregation of carbon nanotube on curved surfaces by polymer induced depletion attraction
Authors: Lee Hsin-Chieh , Jiang Hong-Ren
Published: December 2017

In this study, we show that by chemically grafting macromolecule, polyethylene glycol (PEG), onto CNTs, PEG-CNTs become dispersible in an aqueous solution with tunable depletion interactions with each other. The aggregation of the PEG-CNTs can be controlled by adding PEG polymers into the solution. PEG-CNTs not only aggregate with each other but also tend to aggregate on curved surfaces. Due to this property, we show that PEG-CNTs can be directed to aggregate on particles and patterned surfaces. Depletion interaction induced aggregation of PEG-CNTs may provide a method to place PEG-CNTs on a specific position for different applications ranging from biomedical to industrial usages.
Brownian motion probe for water-ethanol inhomogeneous mixtures
Authors: Furukawa Kazuki , Judai Ken
Published: December 2017

Brownian motion provides information regarding the microscopic geometry and motion of molecules, insofar as it occurs as a result of molecular collisions with a colloid particle. We found that the mobility of polystyrene beads from the Brownian motion in a water-ethanol mixture is larger than that predicted from the liquid shear viscosity. This indicates that mixing water and ethanol is inhomogeneous in micron-sized probe beads. The discrepancy between the mobility of Brownian motion and liquid mobility can be explained by the way the rotation of the beads in an inhomogeneous viscous solvent converts the translational movement.
Numerical approach based on Bernstein polynomials for solving mixed Volterra-Fredholm integral equations
Authors: Khan Faheem , Mustafa Ghulam , Omar Muhammad , Komal Haziqa
Published: December 2017

This paper provides an effective numerical technique for obtaining the approximate solution of mixed Volterra-Fredholm Integral Equations (VFIEs) of second kind. The VFIEs arise from parabolic boundary value problems, mathematical modelling of the spatio-temporal development of an epidemic, and from various physical and Engineering models. The proposed method is based on the discretization of VFIEs by Bernstein’s approximation. Some results on convergence are also established which suggests that the technique converges to a smooth approximate solution. Its remarkable accuracy properties are finally demonstrated by several examples with graphical representation.
High transmittance contrast in amorphous to hexagonal phase of Ge2Sb2Te5: Reversible NIR-window
Authors: Singh Palwinder , Singh A. P. , Kanda Neetu , Mishra Monu , Gupta Govind , Thakur Anup
Published: December 2017

Ge2Sb2Te5 (GST) is one of the best phase change materials because of its splendid set of properties, viz., high thermal stability, fast crystallization speed, good endurance, scalability, and reliability. Phase transition [amorphous → face centered cubic (fcc) → hexagonal close packed (hcp)] of GST thin films with annealing was studied using X-ray diffraction. Thin films in amorphous, fcc, and hcp phases are highly, medium, and negligible transparent in the near infra-red region, respectively. The optical transmission in amorphous, fcc, and hcp phases is ∼92%, ∼46%, and ∼2%, respectively, at the wavelength of 2740 nm. At 2740 nm, a high transmission contrast (∼90%) is observed with phase transition from the amorphous to hcp phase. By utilizing large transmission contrast, it is demonstrated that GST can be availed as a potential candidate for reversible near infra-red-window. The sharp change in optical transmission with phase transition can be understood from the change in density of states in the valence band.
Indications for a fragile-to-strong transition in the high- and low-temperature viscosity of the Fe43Cr16Mo16C15B10 bulk metallic glass-forming alloy
Authors: Bochtler Benedikt , Gross Oliver , Busch Ralf
Published: December 2017

Viscosity of the Fe-based bulk metallic glass-forming liquid Fe43Cr16Mo16C15B10 is measured around the glass transition and in the stable liquid. Low-temperature measurements are conducted using three-point beam bending in a thermomechanical analyzer, and high-temperature data are obtained from the damping behavior of an oscillating droplet which is electromagnetically levitated in microgravity on a reduced-gravity aircraft. The alloy displays an intermediately strong liquid behavior (D* = 15.1) at low temperatures and a fragile behavior (D* = 7.9) at high temperatures. Hence, the temperature dependence of viscosity changes drastically between the high- and the low-temperature regime, which suggests the existence of a fragile-to-strong liquid-liquid transition in the supercooled liquid. Furthermore, viscosity and fragility data are discussed with respect to the glass-forming ability of the alloy.
Comparison of nanoparticle diffusion using fluorescence correlation spectroscopy and differential dynamic microscopy within concentrated polymer solutions
Authors: Shokeen Namita , Issa Christopher , Mukhopadhyay Ashis
Published: December 2017

We studied the diffusion of nanoparticles (NPs) within aqueous entangled solutions of polyethylene oxide (PEO) by using two different optical techniques. Fluorescence correlation spectroscopy, a method widely used to investigate nanoparticle dynamics in polymer solution, was used to measure the long-time diffusion coefficient (D) of 25 nm radius particles within high molecular weight, Mw = 600 kg/mol PEO in water solutions. Differential dynamic microscopy (DDM) was used to determine the wave-vector dependent dynamics of NPs within the same polymer solutions. Our results showed good agreement between the two methods, including demonstration of normal diffusion and almost identical diffusion coefficients obtained by both techniques. The research extends the scope of DDM to study the dynamics and rheological properties of soft matter at a nanoscale. The measured diffusion coefficients followed a scaling theory, which can be explained by the coupling between polymer dynamics and NP motion.
In situ measurements of degraded mixed ionic conductors reveal temperature’s role
Authors: Liebendorfer Adam
Published: December 2017

An in situ impedance approach in an applied field offers a way to measure temperature effects on the properties of degrading dielectrics, elucidating how electric fields influence these changes.
Diffusion of alkali metal adatoms decorated on graphene dominates its electrical response
Authors: Majors J. H.
Published: December 2017

The temperature-dependent electrical transport behavior of Li- and K-doped graphene reveals, through DFT calculations and experimental observations, the dominant role of adatom cluster formation.
New signature discovered characterizes structural defects in tin dichalcogenides
Authors: Liebendorfer Adam
Published: December 2017

A cathodoluminescence spectroscopy technique provides a way for researchers to assess how tin disulfide crystals degrade over time, paving the way for broader use of tin dichalcogenides.
RSK2 drives cell motility by serine phosphorylation of LARG and activation of Rho GTPases
Authors: Shi Geng-Xian , Yang Won Seok , Jin Ling , Matter Michelle L. , Ramos Joe W.
Published: December 2017

Significance

Cell motility is a dynamic process that requires the directed application of force and continuous coordinated changes in cell adhesion and cytoskeletal architecture often in response to extracellular stimuli. Here we have defined a mechanism by which RSK2 can promote cell migration and invasion in response to promotility stimuli. We show that in response to these signals RSK2 directly binds the RhoGEF LARG and phosphorylates it, thereby promoting LARG activation of RhoA GTPases. Moreover, we find that RSK2 is important for epidermal growth factor activation of Rho GTPases. These results advance our understanding of cell motility, RSK kinase function, and LARG/RhoA activation by revealing that these pathways are integrated and the precise mechanism by which that is accomplished.
Structural basis of the phosphorylation-independent recognition of cyclin D1 by the SCF
FBXO31
ubiquitin ligase
Authors: Li Yunfeng , Jin Kai , Bunker Eric , Zhang Xiaojuan , Luo Xuemei , Liu Xuedong , Hao Bing
Published: December 2017

Significance

The cyclin D1 proto-oncoprotein is a crucial regulator of cell cycle progression, and excessive cyclin D1 expression and/or activity is a hallmark of many human cancers. The SCF
FBXO31
ubiquitin ligase complex is responsible for targeting cyclin D1 for ubiquitination and degradation, thereby regulating its turnover after DNA damage. In this work, we report the structural, biophysical, and functional characterization of the interaction between cyclin D1 and Skp1–FBXO31. We find that the F-box protein FBXO31 targets cyclin D1 for phosphorylation-independent ubiquitination by recognizing and binding to its extreme C terminus. This knowledge enhances our understanding of the molecular mechanism of FBXO31-mediated cyclin D1 proteolysis following genotoxic stress and may facilitate efforts to identify a novel molecular target for anticancer drug discovery.
Designing a retrievable and scalable cell encapsulation device for potential treatment of type 1 diabetes
Authors: An Duo , Chiu Alan , Flanders James A. , Song Wei , Shou Dahua , Lu Yen-Chun , Grunnet Lars G. , Winkel Louise , Ingvorsen Camilla , Christophersen Nicolaj Strøyer , Fels Johannes Josef , Sand Fredrik Wolfhagen , Ji Yewei , Qi Ling , Pardo Yehudah , Luo Dan , Silberstein Meredith , Fan Jintu , Ma Minglin
Published: December 2017

Significance

Cell encapsulation holds great potential as a better treatment for type 1 diabetes. An encapsulation system that is scalable to a clinically relevant capacity and can be retrieved or replaced whenever needed is highly desirable for clinical applications. Here we report a cell encapsulation device that is readily scalable and conveniently retrievable through a minimally invasive laparoscopic procedure. We demonstrated its mechanical robustness and facile mass transfer as well as its durable function in diabetic mice. We further showed, as a proof of concept, its scalability and retrievability in dogs. We believe this encapsulation device may contribute to a cellular therapy for type 1 diabetes and potentially other endocrine disorders and hormone-deficient diseases.
Impact of an historic underground gas well blowout on the current methane chemistry in a shallow groundwater system
Authors: Schout Gilian , Hartog Niels , Hassanizadeh S. Majid , Griffioen Jasper
Published: December 2017

Significance

The rapid increase in shale gas production in recent years has led to increased attention to its potential negative environmental effects, including the risks of contaminating groundwater with methane and other substances. In this context, the uncontrolled gas migration that is triggered during well blowouts is an understudied environmental hazard. We show that the methane chemistry in shallow groundwater overlying the site of a catastrophic underground blowout continues to be impacted 50 y later. The occurrence of anaerobic methane oxidation limits the spatial extent to which the dissolved thermogenic methane plume could be observed and discerned from local biogenic methane sources. However, it also highlights the requirement to carry out monitoring in close proximity to potential gas leakage sources.
Dynamic force spectroscopy of synthetic oligorotaxane foldamers
Authors: Sluysmans Damien , Devaux Floriane , Bruns Carson J. , Stoddart J. Fraser , Duwez Anne-Sophie
Published: December 2017

Significance

Donor–acceptor oligorotaxane foldamers are a class of molecular switches elegantly incorporating mechanical bonds in a folded molecular architecture. Such examples of foldamers are very rare, leaving the question wide open regarding what might emerge from a synergistic combination of mechanically interlocked molecules and foldamers. Here, using atomic-force-microscopy-based dynamic single-molecule force spectroscopy, we mechanically drive oligorotaxanes out of equilibrium at a wide range of loading rates and observe their exceptional refolding capabilities and the very fast dynamics of the process. The near-equilibrium pulling–relaxing cycles were exploited to determine the energy required to break one single donor–acceptor interaction from the distribution of work trajectories using fluctuation theorems. Our findings highlight the importance of molecular design on the performance of artificial molecular machines.
Genetic variation interacts with experience to determine interindividual differences in learned song
Authors: Mets David G. , Brainard Michael S.
Published: December 2017

Significance

Learning reflects the influence of experience on genetically determined circuitry, but little is known about how experience and genetics interact to determine learned phenotypes. Here, we use vocal learning in songbirds to study genetic influences on learned behavior. We first show that the tempo of learned song is strongly influenced by genetics. However, increasing richness of the learning experience from weak (tutoring by computer) to strong (tutoring by a live bird) reduces this genetic influence in favor of experiential influence. Our results demonstrate a strong, heritable contribution to individual variation in song learning but that the degree of heritability depends profoundly on the quality of instructive experience. Therefore, increasing the richness of instruction can overcome even strong genetic bias.
CO
2
reduction to acetate in mixtures of ultrasmall (Cu)

n

,(Ag)

m

bimetallic nanoparticles
Authors: Wang Ying , Wang Degao , Dares Christopher J. , Marquard Seth L. , Sheridan Matthew V. , Meyer Thomas J.
Published: December 2017

Significance

Efficient reduction of carbon dioxide to useful fuels and chemicals is an important research goal in artificial photosynthesis. Significant progress has been made for the C1 products, CO and HCOO
−
. We report here a procedure based on the use of ultrasmall, monodispersed Cu and Ag bimetallic nanoparticles on thin, electrochemically polymerized poly-Fe(vbpy)
3
(PF
6
)
2
films. They reduce CO
2
to acetate at pH 7 in aqueous HCO
3
−
solutions at relatively high efficiencies with significant rate enhancements with added benzotriazole. In the sequence of clusters, the most efficient results for acetate production were obtained in films of (Cu)
2
,(Ag)
3
with a faradaic efficiency of 21.2% for acetate from CO
2
at −1.33 V vs. reversible hydrogen electrode in 0.5 M KHCO
3
with 8 ppm of added benzotriazole at 0 °C.
Enhancement of hepatic autophagy increases ureagenesis and protects against hyperammonemia
Authors: Soria Leandro R. , Allegri Gabriella , Melck Dominique , Pastore Nunzia , Annunziata Patrizia , Paris Debora , Polishchuk Elena , Nusco Edoardo , Thöny Beat , Motta Andrea , Häberle Johannes , Ballabio Andrea , Brunetti-Pierri Nicola
Published: December 2017

Significance

Waste nitrogen is converted into urea by the healthy liver. Systemic ammonia is elevated in patients with inherited urea-cycle disorders or acute and chronic liver diseases. Hyperammonemia is a challenging medical condition that holds high risks of mortality and irreversible brain damage. Current treatments are often inadequate. Autophagy is a lysosomal recycling pathway that plays a major role in metabolism. Here, we found that liver autophagy is involved in ammonia homeostasis in vivo and that enhancement of hepatic autophagy increases ureagenesis by providing key urea-cycle intermediates and ATP. Importantly, pharmacological enhancement of autophagy protects against hyperammonemia resulting from both inherited and acquired causes. These findings may lead to development of new drugs promoting ammonia clearance in patients with hyperammonemia.
Protonation state of glutamate 73 regulates the formation of a specific dimeric association of mVDAC1
Authors: Bergdoll Lucie A. , Lerch Michael T. , Patrick John W. , Belardo Kendrick , Altenbach Christian , Bisignano Paola , Laganowsky Arthur , Grabe Michael , Hubbell Wayne L. , Abramson Jeff
Published: December 2017

Significance

Cellular acidification occurs in response to many cellular events, including ischemia and apoptosis. The voltage-dependent anion channel (VDAC) is the most abundant protein in the outer mitochondrial membrane and has been implicated in mitochondrial regulation, cell death, and assembling protein complexes with Bcl2 family of apoptotic regulating proteins. During apoptosis, VDAC has demonstrated rapid oligomerization followed by cytochrome
c
release into the cytoplasm. We report a new dimeric model of VDAC induced by minor acidification with a pKa of 7.4, which is regulated by the protonation state of transmembrane residue E73. This study links a specific dimer formation with cellular acidification, which may be a salient feature of the molecular mechanism(s) involved in mitochondrial regulation.
A mixed-scale dense convolutional neural network for image analysis
Authors: Pelt Daniël M. , Sethian James A.
Published: December 2017

Significance

Popular neural networks for image-processing problems often contain many different operations, multiple layers of connections, and a large number of trainable parameters, often exceeding several million. They are typically tailored to specific applications, making it difficult to apply a network that is successful in one application to different applications. Here, we introduce a neural network architecture that is less complex than existing networks, is easy to train, and achieves accurate results with relatively few trainable parameters. The network automatically adapts to a specific problem, allowing the same network to be applied to a wide variety of different problems.
Coordinating carbon and nitrogen metabolic signaling through the cyanobacterial global repressor NdhR
Authors: Jiang Yong-Liang , Wang Xue-Ping , Sun Hui , Han Shu-Jing , Li Wei-Fang , Cui Ning , Lin Gui-Ming , Zhang Ju-Yuan , Cheng Wang , Cao Dong-Dong , Zhang Zhi-Yong , Zhang Cheng-Cai , Chen Yuxing , Zhou Cong-Zhao
Published: December 2017

Significance

The homeostasis of carbon and nitrogen metabolism needs to be tightly regulated for cell acclimation to fluctuating environments. The related metabolic pathways are ultimately coordinated by the master transcription factors that sense the intracellular metabolites. We report here biochemical, structural, and functional studies of the fine regulation of the transcriptional repressor NAD(P)H dehydrogenase regulator (NdhR). Two key metabolites, 2-OG from the Krebs cycle and 2-PG from photorespiration, have opposite effects on the regulatory activity of NdhR. We propose that 2-OG and 2-PG function together as indicators of intracellular carbon/nitrogen status and that NdhR senses these two effectors in a mutually exclusive manner. Our findings together with previous studies provide a model for the fine coordination of carbon and nitrogen metabolic signaling.
ALKBH5-dependent m6A demethylation controls splicing and stability of long 3′-UTR mRNAs in male germ cells
Authors: Tang Chong , Klukovich Rachel , Peng Hongying , Wang Zhuqing , Yu Tian , Zhang Ying , Zheng Huili , Klungland Arne , Yan Wei
Published: December 2017

Significance

N6-methyladnosine (m6A) represents one of the most common RNA modifications. Biochemical analyses have identified ALKBH5 as an eraser of m6A. The present study represents the first molecular characterization of the
Alkbh5
knockout mouse model. Our data associate m6A erasure with mRNA length control. Specifically, proper m6A demethylation is required for correct splicing and selective degradation of longer 3′-UTR transcripts, which are abundant in mitotic and meiotic male germ cells, but these longer 3′-UTR transcripts become rapidly degraded in the haploid male germ cells. Aberrant m6A levels in spermatogenic cells are incompatible with normal spermatogenesis and male fertility.
From in silico hit to long-acting late-stage preclinical candidate to combat HIV-1 infection
Authors: Kudalkar Shalley N. , Beloor Jagadish , Quijano Elias , Spasov Krasimir A. , Lee Won-Gil , Cisneros José A. , Saltzman W. Mark , Kumar Priti , Jorgensen William L. , Anderson Karen S.
Published: December 2017

Significance

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) are essential components of highly active antiretroviral therapy; however, concerns about poor pharmacological properties, dose restriction because of toxicity, and drug resistance have limited treatment options. Our computational and structure-guided design studies for lead optimization have transformed a 5 µM virtual screening hit into a class of NNRTIs with remarkable potency, safety, drug resistance profile, and pharmacological properties. We report a representative, compound I, with marked synergy with existing HIV-1 drugs and antiviral efficacy in HIV-1–infected humanized mice. A single dose of long-acting nanoformulation of compound I retains sustained levels and efficacy for ∼3 weeks, confirming potential as a late-stage preclinical candidate. Additionally, these properties of compound I suggest that it may be a promising candidate to evaluate for preexposure prophylaxis.
Inactivation of porcine interleukin-1β results in failure of rapid conceptus elongation
Authors: Whyte Jeffrey J. , Meyer Ashley E. , Spate Lee D. , Benne Joshua A. , Cecil Raissa , Samuel Melissa S. , Murphy Clifton N. , Prather Randall S. , Geisert Rodney D.
Published: December 2017

Significance

Establishment of pregnancy in pigs requires that conceptuses produce estrogen to maintain functional corpora lutea throughout gestation and rapidly elongate to provide adequate surface area for nutrient flow through its epitheliochorial placenta. Early conceptus development in the pig is unique in that conceptuses rapidly elongate to long filamentous threads within 1 to 2 h. Conceptus
IL1B2
gene and protein expression increase during the period of conceptus elongation. Using the CRISPR/Cas9 gene-editing system, we successfully knocked out pig conceptus
IL1B2
expression and demonstrate that conceptus elongation was inhibited. This research provides insight into the biological role of IL1B2 in pig conceptus development and demonstrates the use of the CRISPR/Cas9 gene-editing system to evaluate genes during early conceptus development.
Neuronal delivery of Hedgehog directs spatial patterning of taste organ regeneration
Authors: Lu Wan-Jin , Mann Randall K. , Nguyen Allison , Bi Tingting , Silverstein Max , Tang Jean Y. , Chen Xiaoke , Beachy Philip A.
Published: December 2017

Significance

The maintenance of taste sensory organs (taste buds) in the tongue has been known for 140 years to depend on sensory innervation from distant neurons by an unknown mechanism. We find that maintenance and regeneration of taste receptor cells (TRCs) within taste buds requires neuronal delivery of the Sonic hedgehog (Shh) protein signal, thus explaining loss of taste sensation associated with Hedgehog pathway antagonism in patients and illustrating the principle that spatial patterning of TRC regeneration is specified by the projection pattern of Shh-expressing sensory neurons. We also find that pharmacologic Hedgehog pathway activation accelerates TRC recovery, suggesting a means to ameliorate the loss of taste sensation and appetite and the associated delay in recovery in cancer patients undergoing chemotherapy.
Familial Parkinson’s point mutation abolishes multiple system atrophy prion replication
Authors: Woerman Amanda L. , Kazmi Sabeen A. , Patel Smita , Aoyagi Atsushi , Oehler Abby , Widjaja Kartika , Mordes Daniel A. , Olson Steven H. , Prusiner Stanley B.
Published: December 2017

In the neurodegenerative disease multiple system atrophy (MSA), α-synuclein misfolds into a self-templating conformation to become a prion. To compare the biological activity of α-synuclein prions in MSA and Parkinson’s disease (PD), we developed nine α-synuclein−YFP cell lines expressing point mutations responsible for inherited PD. MSA prions robustly infected wild-type, A30P, and A53T α-synuclein–YFP cells, but they were unable to replicate in cells expressing the E46K mutation. Coexpression of the A53T and E46K mutations was unable to rescue MSA prion infection in vitro, establishing that MSA α-synuclein prions are conformationally distinct from the misfolded α-synuclein in PD patients. This observation may have profound implications for developing treatments for neurodegenerative diseases.
Moral priorities under risk
Authors: Lee-Stronach Chad
Published: December 2017

Many moral theories are committed to the idea that some kinds of moral considerations should be respected, whatever the cost to ‘lesser’ types of considerations. A person's life, for instance, should not be sacrificed for the trivial pleasures of others, no matter how many would benefit. However, according to the decision-theoretic critique of lexical priority theories, accepting lexical priorities inevitably leads us to make unacceptable decisions in risky situations. It seems that to operate in a risky world, we must reject lexical priorities altogether. This paper argues that lexical priority theories can, in fact, offer satisfactory guidance in risky situations. It does so by equipping lexical priority theories with overlooked resources from decision theory.
Novel high-entropy and medium-entropy stainless steels with enhanced mechanical and anti-corrosion properties
Authors: Zhang H. , Tang H. , Li W. H. , Wu J.L. , Zhong X. C. , Chen G. , Guo S.
Published: December 2017

Novel high-entropy and medium-entropy stainless steels (MESS), containing a high amount of alloying elements, were designed and prepared by arc melting. These high-entropy and MESS possess a simple phase constitution, mainly solid solution phases, and noticeably exhibit excellent anti-corrosion properties in sulphuric acid. In particular, an austenitic Fe65Cr13Co4.75Mn4.75Mo4.75Ni4.75Cu3 (at.-%) alloy has a higher hardness of 182 HV and better corrosion resistance than those of the 00Cr19Ni14Mn2 austenitic stainless steel prepared under the same condition; a ferritic precipitation hardening Fe65Cr13Al3.167Co3.167Mn3.167Mo3.167Ni3.167Ti3.167Cu3 (at.-%) alloy was also developed, with a higher hardness of 584 HV and even better corrosion resistance.
S100A4 regulates macrophage invasion by distinct myosin-dependent and myosin-independent mechanisms
Authors: Dulyaninova Natalya G. , Ruiz Penelope D. , Gamble Matthew J. , Backer Jonathan M. , Bresnick Anne R.
Published: December 2017

S100A4, a member of the S100 family of Ca2+-binding proteins, is a key regulator of cell migration and invasion. Our previous studies showed that bone marrow–derived macrophages from S100A4−/−mice exhibit defects in directional motility and chemotaxis in vitro and reduced recruitment to sites of inflammation in vivo. We now show that the loss of S100A4 produces two mechanistically distinct phenotypes with regard to macrophage invasion: a defect in matrix degradation, due to a disruption of podosome rosettes caused by myosin-IIA overassembly, and a myosin-independent increase in microtubule acetylation, which increases podosome rosette stability and is sufficient to inhibit macrophage invasion. Our studies point to S100A4 as a critical regulator of matrix degradation, whose actions converge on the dynamics and degradative functions of podosome rosettes.
Recognizing thyrotoxic hypokalemic periodic paralysis
Authors: Patel Kamini , McCoy Jonathan V. , Davis Patrick M.
Published: December 2017

Thyrotoxic hypokalemic periodic paralysis (THPP) is a rare but potentially serious complication of thyrotoxicosis. The resulting muscle weakness is profound, associated with more severe hypokalemia, yet reversible. However, clinicians must be cautious because patients can develop life-threatening hyperkalemia during treatment. Underlying causes should be investigated as repeated episodes of THPP may occur.
Creating Structured Opportunities for Social Engagement to Promote Well-Being and Avoid Burnout in Medical Students and Residents
Authors: Ziegelstein Roy C.
Published: December 2017

Increasing attention is being paid to medical student and resident well-being, as well as to enhancing resilience and avoiding burnout in medical trainees. Medical schools and residency programs are implementing wellness initiatives that often include meditation and other mindfulness activities, self-reflection, journaling, and lectures or workshops on resilience tools such as metacognition and cognitive restructuring. These interventions have in common the creation of opportunities for trainees to become more aware of their experiences, to better recognize stressors, and to regulate their thoughts and feelings so that stressors are less likely to have harmful effects. They often enable trainees to temporarily distance themselves mentally and emotionally from a stressful environment. In this Invited Commentary, the author suggests that medical school leaders and residency program directors should also create structured opportunities for trainees to establish meaningful connections with each other to provide greater social support and thereby reduce the harmful effects of stress. Social connection and engagement, as well as group identification, have potential to promote well-being and reduce burnout during training.
OUTCOMES OF VITRECTOMY WITH SILICONE OIL TAMPONADE FOR MANAGEMENT OF RETINAL DETACHMENT IN EYES WITH CHORIORETINAL COLOBOMA
Authors: Hocaoglu Mumin , Karacorlu Murat , Ersoz Mehmet G. , Sayman Muslubas Isil , Arf Serra
Published: December 2017

Purpose:

To estimate the outcomes of retinal detachment in eyes with chorioretinal coloboma managed by pars plana vitrectomy and silicone oil tamponade.

Methods:

A retrospective chart review of 10 eyes (10 patients) who underwent pars plana vitrectomy for retinal detachment with chorioretinal coloboma.

Results:

The average age at the time of the surgery was 29.8 ± 19.7 years. The mean follow-up period was 28.8 ± 28.4 months. The mean silicone oil tamponade duration was 9.8 ± 3.5 weeks. Of 10 eyes, 4 (40%) had retinal breaks outside the coloboma, 4 (40%) had breaks inside the coloboma, 1 (10%) had breaks inside and outside the coloboma, and in 1 eye (10%); the causative retinal break was not localized. Preoperatively, the mean visual acuity was 20/2,500 (n = 9), and 1 (10%) was recorded as “Not CSM.” At the final examination, the mean visual acuity for the patients with measurable visual acuity was 20/200 (P = 0.06), and in the remaining eye was recorded as light perception. The retina was finally reattached in nine eyes (90%). Postoperative complications included cataract in three (30%), persistent elevated intraocular pressure in one (10%), band keratopathy in one (10%), and proliferative vitreoretinopathy in one (10%).

Conclusion:

Complete pars plana vitrectomy with or without lensectomy, laser photocoagulation around the peripheral retina, around all the peripheral breaks and around the colobomatous area, and silicone oil tamponade is effective for retinal detachment in eyes with chorioretinal coloboma. Silicone oil removal as early as possible did not increase the risk of redetachment and seems to reduce the incidence of oil-related complications in such cases.
Early complications in cases series in implant-based immediate breast reconstruction with a biological acellular matrix during the learning curve of this technique and using 3 different matrices: a case series of 84 breasts
Authors: Aguilera-Sáez Jorge , Bosacoma Roura Pau , Garrido Ferrer Anselmo , Guinot Madridejos Alberto , Barret Juan P.
Published: December 2017

Introduction:

We present our experience in implant-based immediate breast reconstruction (IBIBR) with biological acellular matrix during our learning curve and compare the complications with the use of three different matrices.

Materials and methods:

We did a retrospective study on patients who underwent an IBIBR with acellular matrix after skin sparing mastectomy with or without nipple-areolar complex preservation at the Breast Pathology Unit at University Hospital Vall d’Hebron, Barcelona (Spain) between July 2011 and December 2014.

Results:

A total of 84 breasts were reconstructed in 71 women. A therapeutic mastectomy was performed in 55 of them (65.5%) and a prophylactic mastectomy in 29 (34.5%). The total rate of complications was 41.67% (35 patients): we found 11 cases of erythema (13.1%), 19 cases of seroma (22.62%), 9 cases of hematoma (10.71%), 17 cases of wound dehiscence (20.24%), 11 cases of skin flap necrosis (13.1%), and 10 cases of reconstruction failure (11.9%). The probability of reconstruction failure was higher in smokers and former smokers (P=0.0011%). There were more complications with the Protexa matrix than with the other 2, Strattice and Tutomesh (P<0.001) and a higher risk of reconstruction failure as well (P=0.03).

Conclusions:

In our experience the use of acellular matrix in IBIBR can have a high rate of complications, especially during the learning curve. Therefore, the selection of suitable patients and the better matrix is an issue of great importance to achieve favorable results.
Spermatocytic Seminoma
Authors: Hu Rong , Ulbright Thomas M. , Young Robert H.
Published: December 2017

Spermatocytic seminoma (or, alternatively, spermatocytic tumor) of the testis is rare and errors in pathologic diagnosis are still made. As it has a good prognosis, except when it, rarely, undergoes sarcomatous transformation, accurate diagnosis and differentiating it from usual seminoma and other malignant neoplasms such as lymphoma are crucial. To potentially contribute information of diagnostic aid we reviewed the largest series of cases reported to date to characterize in detail their histologic spectrum. The patients ranged from 30 to 81 years (average, 52 y); 30% were in the fourth decade. The neoplasms ranged from 1.4 to 15 cm (average, 5.7 cm). Most were fleshy, soft, and often lobulated and 11 were edematous or mucoid. Low-power microscopic examination either showed a predominant multinodular (43/85) or diffuse (42/85) pattern. All tumors had the classic “tripartite” cellular population. Five tumors showed a relatively monomorphic population of the intermediate cell type with vesicular chromatin and very prominent nucleoli, at least focally. Two tumors underwent sarcomatous transformation, with 1 having a focus of atypical cartilage. Additional findings, some not previously reported or emphasized, included: (1) frequent edema fluid (87%) often causing spaces, both follicle-like (24%) and irregular (39%), a finding seen in some usual seminomas (but less frequently) and rarely seen in lymphomas; (2) tumor nodules showing partial rims of fibrin (20%); (3) a distinctive arrangement of connecting tumor islands (19%); (4) prominent lymphocytic infiltrates (8%); (5) granulomatous inflammation (1%); (6) striking mitotic activity and apoptosis; (7) intratubular spread (64%); and (8) vessel invasion (11%) and necrosis (8%). Awareness of these aspects may be of importance either at the time of intraoperative evaluation or on final pathologic analysis and help avoid significant errors in diagnosis.
Brief Report: Disclosure, Consent, Opportunity Costs, and Inaccurate Risk Assessment Deter Pediatric HIV Testing: A Mixed-Methods Study
Authors: Wagner Anjuli D. , O'Malley Gabrielle , Firdawsi Olivia , Mugo Cyrus , Njuguna Irene N. , Maleche-Obimbo Elizabeth , Inwani Irene W. , Wamalwa Dalton C. , John-Stewart Grace C. , Slyker Jennifer A.
Published: December 2017

Background:

Prompt child HIV testing and treatment is critical; however, children are often not diagnosed until symptomatic. Understanding factors that influence pediatric HIV testing can inform strategies to increase testing.

Methods:

A mixed-methods study was conducted at a tertiary hospital in Nairobi, Kenya. Three focus group discussions with health care workers (HCWs) and 18 in-depth interviews with HIV-infected adults with children of unknown status were analyzed using thematic analysis. A structured questionnaire was administered to 116 HIV-infected caregivers of children of unknown status to triangulate qualitative findings.

Results:

Analysis revealed 3 key periods of the pediatric HIV testing process: decision to test, test visit, and posttest. Key issues included: decision to test: inaccurate HIV risk perception for children, challenges with paternal consent, lack of caregiver HIV status disclosure to partners or older children; test experience: poor understanding of child consent/assent and disclosure guidelines, perceived costs of testing and care, school schedules, HCW discomfort with pediatric HIV testing; and posttest: pessimism regarding HIV-infected children's prognosis, caregiver concerns about their own emotional health if their child is positive, and challenges communicating about HIV with children. Concerns about all 3 periods influenced child testing decisions. In addition, 3 challenges were unique to pediatric HIV: inaccurate HIV risk perception for children; disclosure, consent, and permission; and costs and scheduling.

Conclusions:

Pediatric HIV testing barriers are distinct from adult barriers. Uptake of pediatric HIV testing may be enhanced by interventions to address misconceptions, disclosure services, psychosocial support addressing concerns unique to pediatric testing, child-focused HCW training, and alternative clinic hours.
Evaluating and Improving the Efficiency of Patient Flow in the Bronchoscopy Suite in a Tertiary Care Center: A QI Project!
Authors: Krvavac Armin , Kamel Ghassan , Patel Pujan P. , Rakey Erin , Mwangi John , Jamkhana Zafar , Patolia Setu
Published: December 2017

Purpose:

The bronchoscopy suite is where pulmonologists perform the majority of their procedures like bronchoscopy, endobronchial ultrasound, and navigational bronchoscopy among others. Faculty and fellows in our division have reported multiple delays in the procedure start time in our bronchoscopy.

Objectives:

Objectives of the study were (1) to identify the areas of delays in procedure start time, (2) to identify potential high-yield areas of interventions to reduce delays, (3) to assess the impact of interventions on efficacy of bronchoscopy suit.

Methods:

We have conducted a quality improvement project aiming at identifying areas of delays and implemented an intervention aiming at minimizing those delays. We retrospectively collected the data about the patient flow from arrival to hospital to discharge between June and August 2016. We used fishbone technique to identify the potential reasons for delay in procedures and to identify low-effort high-yield areas. Our intervention was raising awareness and education among the personnel and designing the process to reduce time delays and improve efficacy. We collected the data about the patient flow prospectively after the invention was implemented.

Results:

The study showed that 76.4% of our preintervention procedures had a late start time. The postintervention results revealed a statistically significant reduction in the procedure late start times by 24.4% (P = .02). Signing the procedure H and P was also identified as a major area of delay, which has improved postintervention (65.5 % vs 33.3%, P = 0.017).

Conclusion:

The faculty and fellows' perceptions were translated into objective data, which serves as a first step in our division to improve the patient flow process in the bronchoscopy suite. Areas of delays were identified and our intervention resulted in significant improvement, but more work needs to be done to achieve a more efficient patient flow in the bronchoscopy suite while maintaining a safe patient care.
Order and gelation of cellulose nanocrystal suspensions: an overview of some issues
Authors: Gray Derek G.
Published: December 2017

Cellulose nanocrystals (CNCs) are polydisperse rod-shaped particles of crystalline cellulose I, typically prepared by sulfuric acid hydrolysis of natural cellulose fibres to give aqueous colloidal suspensions stabilized by sulfate half-ester groups. Sufficiently dilute suspensions are isotropic fluids, but as the concentration of CNC in water is increased, a critical concentration is reached where a spontaneously ordered phase is observed. The (equilibrium) phase separation of the ordered chiral nematic phase is in competition with a tendency of the CNC suspension to form a gel. Qualitatively, factors that reduce the stability of the CNC suspension favour the onset of gelation. The chiral nematic structure is preserved, at least partially, when the suspension dries. Solid chiral nematic films of cellulose are of interest for their optical and templating properties, but the preparation of the films requires improvement. The processes that govern the formation of solid chiral nematic films from CNC suspensions include phase separation, gelation and also the effects of shear on CNC orientation during evaporation. Some insight into these processes is provided by polarized light microscopy, which indicates that the relaxation of shear-induced orientation to give a chiral nematic structure may occur via an intermediate twist-bend state.

This article is part of a discussion meeting issue ‘New horizons for cellulose nanotechnology’.
Optimization of cellulose nanocrystal length and surface charge density through phosphoric acid hydrolysis
Authors: Vanderfleet Oriana M. , Osorio Daniel A. , Cranston Emily D.
Published: December 2017

Cellulose nanocrystals (CNCs) are emerging nanomaterials with a large range of potential applications. CNCs are typically produced through acid hydrolysis with sulfuric acid; however, phosphoric acid has the advantage of generating CNCs with higher thermal stability. This paper presents a design of experiments approach to optimize the hydrolysis of CNCs from cotton with phosphoric acid. Hydrolysis time, temperature and acid concentration were varied across nine experiments and a linear least-squares regression analysis was applied to understand the effects of these parameters on CNC properties. In all but one case, rod-shaped nanoparticles with a high degree of crystallinity and thermal stability were produced. A statistical model was generated to predict CNC length, and trends in phosphate content and zeta potential were elucidated. The CNC length could be tuned over a relatively large range (238–475 nm) and the polydispersity could be narrowed most effectively by increasing the hydrolysis temperature and acid concentration. The CNC phosphate content was most affected by hydrolysis temperature and time; however, the charge density and colloidal stability were considered low compared with sulfuric acid hydrolysed CNCs. This study provides insight into weak acid hydrolysis and proposes ‘design rules’ for CNCs with improved size uniformity and charge density.

This article is part of a discussion meeting issue ‘New horizons for cellulose nanotechnology’.