Publications by authors named "W Troy Shelton"

139 Publications

Annihilation and Control of Chiral Domain Walls with Magnetic Fields.

Nano Lett 2021 Feb 25;21(3):1205-1212. Epub 2021 Jan 25.

Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, United States.

The control of domain walls is central to nearly all magnetic technologies, particularly for information storage and spintronics. Creative attempts to increase storage density need to overcome volatility due to thermal fluctuations of nanoscopic domains and heating limitations. Topological defects, such as solitons, skyrmions, and merons, may be much less susceptible to fluctuations, owing to topological constraints, while also being controllable with low current densities. Here, we present the first evidence for soliton/soliton and soliton/antisoliton domain walls in the hexagonal chiral magnet MnNbS that respond asymmetrically to magnetic fields and exhibit pair-annihilation. This is important because it suggests the possibility of controlling the occurrence of soliton pairs and the use of small fields or small currents to control nanoscopic magnetic domains. Specifically, our data suggest that either soliton/soliton or soliton/antisoliton pairs can be stabilized by tuning the balance between intrinsic exchange interactions and long-range magnetostatics in restricted geometries.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.nanolett.0c03199DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7883385PMC
February 2021

Adsorption of Myoglobin and Corona Formation on Silica Nanoparticles.

Langmuir 2020 12 19;36(47):14157-14165. Epub 2020 Nov 19.

Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, Louisiana 70808, United States.

The adsorption of proteins from aqueous medium leads to the formation of protein corona on nanoparticles. The formation of protein corona is governed by a complex interplay of protein-particle and protein-protein interactions, such as electrostatics, van der Waals, hydrophobic, hydrogen bonding, and solvation. The experimental parameters influencing these interactions, and thus governing the protein corona formation on nanoparticles, are currently poorly understood. This lack of understanding is due to the complexity in the surface charge distribution and anisotropic shape of the protein molecules. Here, we investigate the effect of pH and salinity on the characteristics of corona formed by myoglobin on silica nanoparticles. We experimentally measure and theoretically model the adsorption isotherms of myoglobin binding to silica nanoparticles. By combining adsorption studies with surface electrostatic mapping of myoglobin, we demonstrate that a monolayered hard corona is formed in low salinity dispersions, which transforms into a multilayered hard + soft corona upon the addition of salt. We attribute the observed changes in protein adsorption behavior with increasing pH and salinity to the change in electrostatic interactions and surface charge regulation effects. This study provides insights into the mechanism of protein adsorption and corona formation on nanoparticles, which would guide future studies on optimizing nanoparticle design for maximum functional benefits and minimum toxicity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.langmuir.0c01613DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7735741PMC
December 2020

Importance of van der Waals interactions for ab initio studies of topological insulators.

J Phys Condens Matter 2020 Oct 2. Epub 2020 Oct 2.

Physics and Astronomy, Louisiana State University and A&M College, Baton Rouge, Baton Rouge, Louisiana, LA 70803-4001, UNITED STATES.

We investigate the lattice and electronic structures of the bulk and surface of the prototypical layered topological insulators BiSeand BiTeusing ab initio density functional methods, and systematically compare the results of different methods of including van der Waals (vdW) interactions. We show that the methods utilizing semi-empirical energy corrections yield accurate descriptions of these materials, with the most precise results obtained by properly accounting for the long-range tail of the vdW interactions. The bulk lattice constants, distances between quintuple layers and the Dirac velocity of the topological surface states (TSS) are all in excellent agreement with experiment. In BiTe, hexagonal warping of the energy dispersion leads to complex spin textures of the TSS at moderate energies, while in BiSethese states remain almost perfectly helical away from the Dirac point, showing appreciable signs of hexagonal warping at much higher energies, above the minimum of the bulk conduction band. Our results establish a framework for unified and systematic self-consistent first principles calculations of topological insulators in bulk, slab and interface geometries, and provides the necessary first step towards ab initio modeling of topological heterostructures.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1088/1361-648X/abbdbcDOI Listing
October 2020

Improving motility and fertilization capacity of low-quality sperm of sterlet Acipenser ruthenus during storage.

Theriogenology 2020 Oct 8;156:90-96. Epub 2020 Jul 8.

University of South Bohemia in Ceske Budejovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Research Institute of Fish Culture and Hydrobiology, Vodnany, Czech Republic. Electronic address:

Improvement of sperm quality with low motility by storage could ensure higher success of fertilization and maintain higher genetic diversity, especially for sturgeons, which as endangered species have limited broodstock and gametes. Sperm was collected from mature male sterlet Acipenser ruthenus and motility was evaluated using the CASA system; samples were categorized as GS 'good sperm' (>80%) or BS 'bad sperm' (<20%). Samples from both groups were incubated with seminal plasma from good- (GSP) and bad-quality sperm (BSP), respectively for 15 min, 6 h, 24 h and 96 h at 4 °C. Motility of BS incubated in GSP increased after different storage times compared to BS incubated in BSP, while the motility and velocity of GS incubated in BSP decreased compared to GS incubated in GSP. Fertilization rates were evaluated with samples stored for 15 min and 6 h post-stripping; fertilization and hatching rate of BS after incubation in GSP increased significantly compared to the BS incubated in BSP. Inorganic ion (Na, K, Cl) concentrations and osmolality of BSP were significantly lower than that of GSP. These results indicated that sterlet sperm quality can be revitalized by incubation with GSP. Further, fertilization capacity of BS after incubation in GSP can reach similar levels to the good quality sperm (∼70%). Low ion concentration and osmolality in BSP may be a partial cause of low sperm quality. The current study is the first report on the capability to revitalize low quality sterlet sperm by storage in GSP.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.theriogenology.2020.07.004DOI Listing
October 2020

NWChem: Past, present, and future.

J Chem Phys 2020 May;152(18):184102

Institute for Advanced Computational Science, Stony Brook University, Stony Brook, New York 11794, USA.

Specialized computational chemistry packages have permanently reshaped the landscape of chemical and materials science by providing tools to support and guide experimental efforts and for the prediction of atomistic and electronic properties. In this regard, electronic structure packages have played a special role by using first-principle-driven methodologies to model complex chemical and materials processes. Over the past few decades, the rapid development of computing technologies and the tremendous increase in computational power have offered a unique chance to study complex transformations using sophisticated and predictive many-body techniques that describe correlated behavior of electrons in molecular and condensed phase systems at different levels of theory. In enabling these simulations, novel parallel algorithms have been able to take advantage of computational resources to address the polynomial scaling of electronic structure methods. In this paper, we briefly review the NWChem computational chemistry suite, including its history, design principles, parallel tools, current capabilities, outreach, and outlook.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1063/5.0004997DOI Listing
May 2020

A Noble-Transition Alloy Excels at Hot-Carrier Generation in the Near Infrared.

Adv Mater 2020 Jun 29;32(23):e1906478. Epub 2020 Apr 29.

Gordon and Mary Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA, 70803, USA.

Above-equilibrium "hot"-carrier generation in metals is a promising route to convert photons into electrical charge for efficient near-infrared optoelectronics. However, metals that offer both hot-carrier generation in the near-infrared and sufficient carrier lifetimes remain elusive. Alloys can offer emergent properties and new design strategies compared to pure metals. Here, it is shown that a noble-transition alloy, Au Pd , outperforms its constituent metals concerning generation and lifetime of hot carriers when excited in the near-infrared. At optical fiber wavelengths (e.g., 1550 nm), Au Pd provides a 20-fold increase in the number of ≈0.8 eV hot holes, compared to Au, and a threefold increase in the carrier lifetime, compared to Pd. The discovery that noble-transition alloys can excel at hot-carrier generation reveals a new material platform for near-infrared optoelectronic devices.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/adma.201906478DOI Listing
June 2020

Physicians' End of Life Discussions with Patients: Is There an Ethical Obligation to Discuss Aid in Dying?

HEC Forum 2020 Sep;32(3):227-238

Alden March Bioethics Institute, Albany Medical College, Albany, NY, USA.

Since Oregon implemented its Death with Dignity Act, many additional states have followed suit demonstrating a growing understanding and acceptance of aid in dying (AID) processes. Traditionally, the patient has been the one to request and seek this option out. However, as Death with Dignity acts continue to expand, it will impact the role of physicians and bring up questions over whether physicians have the ethical obligation to facilitate a conversation about AID with patients during end of life discussions. Patients have the right to make informed decisions about their health, which implies that physicians have an obligation to discuss with and inform patients of the options that will accomplish the patients' goals of care. We will argue that physicians have an ethical obligation to inform certain patients about AID (in qualifying states) during end of life care discussions. We will also address what this obligation encompasses and explore guidelines of when and how these conversations should occur and proceed. Earlier guidelines, presented by various palliative care and ethics experts, for proceeding with such conversations have mostly agreed that the discussion of hospice and end of life care with patients should be initiated early and that the individual goals of a patient during the remaining duration of life should be thoroughly examined before discussion of appropriate options. In discussing AID, physicians should never recommend but inform patients about the basics so that they can make an informed decision. If patients express further interest in AID, the physician should open up the dialogue to address the reasoning behind this decision versus other possible treatments to ensure that patients clearly comprehend the process and implications of their decision. Ultimately, any end of life choice should be made by patients with the full capacity to express what they envision for the remaining duration of life and to comprehend the advantages and disadvantages of all the possible options.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10730-020-09402-yDOI Listing
September 2020

Optimization of sterlet (Acipenser ruthenus) egg incubation.

Anim Reprod Sci 2020 Apr 26;215:106334. Epub 2020 Feb 26.

University of South Bohemia in Ceske Budejovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Research Institute of Fish Culture and Hydrobiology, Zatisi 728/II, 389 25 Vodnany, Czech Republic. Electronic address:

Sterlet Acipenser ruthenus was used to assess egg and embryo development when incubated at 17 °C in Petri dishes placed in a hatchery tank (300 L recirculating dechlorinated water) with incubation occurring in a static tabletop system in an air-conditioned laboratory, or in a 700 L Q-cell incubator. Eggs in each dish were placed in a plastic box with 300 mL dechlorinated water. Separated eggs from three individual females were fertilized using pooled sperm from four males with there being four replicates. There were no differences (P > 0.05) in mean percentages of neurulation and embryos undergoing cleavage for eggs incubated in the hatchery tank and with use of the static tabletop system. Furthermore, there were no differences (P >  0.05) in percentage of embryos undergoing cleavage, neurulation and hatching for each female when eggs were incubated using the two systems. Results indicate a Petri dish placed in a small plastic box with 300 mL of dechlorinated water was adequate for incubation of sterlet eggs. Results of the study also indicate that with the static system: 1) eggs should be fertilized from each female to retain individual identity; 2) eggs should be dispersed in Petri dishes to avoid clumping; 3) water should be changed at 24 h, but not at 48 h (neurulation) post-fertilization; and 4) embryos that do not optimally develop should be removed the day after neurulation (72 h of post-fertilization period) and water should be exchanged every day subsequent to the 48 h time-point post-fertilization.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.anireprosci.2020.106334DOI Listing
April 2020

Adsorption of Fatty Acid Molecules on Amine-Functionalized Silica Nanoparticles: Surface Organization and Foam Stability.

Langmuir 2020 04 2;36(14):3703-3712. Epub 2020 Apr 2.

Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, Louisiana 70803, United States.

The crucial roles of the ionization state and counterion presence on the phase behavior of fatty acid in aqueous solutions are well-established. However, the effects of counterions on the adsorption and morphological state of fatty acid on nanoparticle surfaces are largely unknown. This knowledge gap exists due to the high complexity of the interactions between nanoparticles, counterions, and fatty acid molecules in aqueous solution. In this study, we use adsorption isotherms, small angle neutron scattering, and all-atom molecular dynamic simulations to investigate the effect of addition of ethanolamine as a counterion on the adsorption and self-assembly of decanoic acid onto aminopropyl-modified silica nanoparticles. We show that the morphology of the fatty acid assemblies on silica nanoparticles changes from discrete surface patches to a continuous bilayer by increasing concentration of the counterion. This morphological behavior of fatty acid on the oppositely charged nanoparticle surface alters the interfacial activity of the fatty acid-nanoparticle complex and thus governs the stability of the foam formed by the mixture. Our study provides new insights into the structure-property relationship of fatty acid-nanoparticle complexes and outlines a framework to program the stability of foams formed by mixtures of nanoparticles and amphiphiles.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.langmuir.0c00156DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7311077PMC
April 2020

Predictors of Open Reduction in Pediatric Femur Fractures Treated With Flexible Nails.

J Pediatr Orthop 2020 Aug;40(7):e566-e571

Children's Hospital New Orleans.

Background: Closed reduction (CR) is sufficient to reduce the majority of femur fractures treated with flexible intramedullary nailing (FIN). No previous study has examined factors associated with failed CR of pediatric femoral shaft fractures treated with FIN. We sought to determine preoperative factors associated with failed CR. We hypothesized that fracture, patient, and surgeon characteristics would impact the need for open reduction (OR).

Methods: A retrospective review of children treated for femur fracture between 2012 and 2017 at a tertiary pediatric hospital was performed. Comparisons were made between 2 groups: FIN with CR group and FIN that required OR group. Demographic and baseline characteristics were compared between treatment groups using either χ tests or Fisher exact tests for categorical variables and general linear models for continuous variables. Odds ratios with 95% confidence intervals were calculated using univariate logistic regression tests.

Results: Of 449 consecutive pediatric femur fractures treated at our center, 85 children were treated with FIN and constituted the study cohort. CR failed in 14 patients (16.5%) necessitating OR of the fracture site. Significant differences between study groups were found in fracture location (P=0.018), the mechanism (P=0.003), and displacement on the anteroposterior radiograph (P=0.027). Surgical time was found to be longer in the OR group (P=0.010). We identified 3 preoperative predictors of OR for FIN including fractures caused by high energy mechanisms (odds ratio=7.5), distal third fractures (odds ratio=15.3), and fracture displacement on the anteroposterior view (odds ratio=1.06). Surgeon years in practice, patient weight, age, and time from injury to surgery were not associated with OR.

Conclusions: This study presents 3 preoperative risk factors that predict the need for OR of femur fractures treated with FIN. Surgical time was longer in cases that required OR. Our findings suggest that surgeons should avoid lengthy attempts at CR and consider a lower threshold for OR of at-risk fractures or use another technique other than flexible nails.

Level Of Evidence: Level III-prognostic.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/BPO.0000000000001511DOI Listing
August 2020

Directed propulsion of spherical particles along three dimensional helical trajectories.

Nat Commun 2019 06 12;10(1):2575. Epub 2019 Jun 12.

Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA, 70803, USA.

Active colloids are a class of microparticles that 'swim' through fluids by breaking the symmetry of the force distribution on their surfaces. Our ability to direct these particles along complex trajectories in three-dimensional (3D) space requires strategies to encode the desired forces and torques at the single particle level. Here, we show that spherical colloids with metal patches of low symmetry self-propel along non-linear 3D trajectories when powered remotely by an alternating current (AC) electric field. In particular, particles with triangular patches of approximate mirror symmetry trace helical paths along the axis of the field. We demonstrate that the speed and shape of the particle's trajectory can be tuned by the applied field strength and the patch geometry. We show that helical motion can enhance particle transport through porous materials with implications for the design of microrobots that can navigate complex environments.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41467-019-10579-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6561940PMC
June 2019

Fish sperm biology in relation to urogenital system structure.

Theriogenology 2019 Jul 15;132:153-163. Epub 2019 Apr 15.

University of South Bohemia in České Budějovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Research Institute of Fish Culture and Hydrobiology, Zátiší 728/II, 389 25, Vodňany, Czech Republic.

Morphology of the urogenital system has evolved during fish speciation. Chondrostei (sturgeons and paddlefishes) possess an excretory system which is called "primitive" in that the sperm ducts enter the kidneys and share the excretory ducts where sperm is mixed with urine before it is released into the spawning environment. Further, in this group of fishes there are also physiological characteristics which are associated with these anatomical features where the mixing of sperm and urine is a prerequisite for the final sperm maturation rather than contamination. In the Holostei (gars and bowfins) which are closely related to the Chondrostei, sperm also naturally mixed with urine, but the physiological role of such mixing for sperm biology has not been described. In contrast, urinary and sperm ducts in the more evolved Teleostei are completely separate, and sperm and urine are not mixed before being released during spawning. Thus, urine constitutes an inappropriate environment which can be a source of problems when sperm is collected during fisheries practices. In this review, the consequences of such divergent conditions in the urogenital anatomy will be considered in relation to general features of fish sperm biology and in relation to aquaculture and fisheries practices.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.theriogenology.2019.04.020DOI Listing
July 2019

Empowering Patients with Alzheimer's Disease To Avoid Unwanted Medical Care: A Look At The Dementia Care Triad.

Am J Alzheimers Dis Other Demen 2018 Dec 13:1533317518817614. Epub 2018 Dec 13.

4 New York State Department of Health, Albany, NY, USA.

Patients with Alzheimer's disease and other types of dementia with acute medical problems, who have lost capacity and are without advance directives, are at risk of being over treated inhospitals. To deal with this growing demographic and ethical crisis, patients with dementia need to plan for their future medical care while they have capacity to do so. This article will examine the role of each member of the dementia care triad and how to empower the patient to participate in planning future medical care. A case will be made that physicians have the same professional disclosure obligations to dementia patients as they do to all other capable patients with terminal illnesses. Because there is little consensus about what facts should be included in a diagnostic disclosure, this article will offer a proposal to empower newly diagnosed patients with dementia with capacity to plan for their future medical care.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/1533317518817614DOI Listing
December 2018

pH-Induced reorientation of cytochrome c on silica nanoparticles.

Soft Matter 2019 Jan 23;15(3):350-354. Epub 2018 Nov 23.

Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA 70803, USA.

The orientation of cytochrome c molecules at the surface of silica nanoparticles was studied in a wide pH range by combining small-angle neutron scattering, adsorption measurements, and molecular dynamics simulations. The results indicate a reorientation of the ellipsoidal protein from head-on to side-on as the pH is increased. This is attributed to changes in the surface charge distribution of both the protein and the nanoparticles.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c8sm01909fDOI Listing
January 2019

Magnetic Field-Driven Convection for Directed Surface Patterning of Colloids.

Langmuir 2018 12 27;34(50):15416-15424. Epub 2018 Nov 27.

Department of Chemical Engineering , University of Louisiana , Lafayette 70503 , Louisiana , United States.

Drying sessile droplets is a promising route to transform colloidal dispersions into surface coatings, which are widely used in material design and biochemical detection. However, directing the assembly of the particles within drying droplets and achieving surface patterns beyond the well-known coffee-ring formation remain a challenge. Here, we present a new principle of directing the assembly of nonmagnetic colloidal particles dispersed in a magnetic fluid and generating unusual surface patterns. We use the ability of ferrofluids to change phases with the application of magnetic fields to program the assembly of nonmagnetic microparticles present in drying sessile droplets. We show that in the absence of external magnetic field, the superparamagnetic nanoparticles in the magnetic fluid are spontaneously transported to the droplet edge because of solvent evaporation. This nanoparticle transport leads to the formation of nanoparticle-rich edge and nanoparticle-depleted center of the drying droplet. Upon the application of a uniform external magnetic field, the asymmetry in the magnetic nanoparticle distribution drives a magnetostatic convection and finger-like instability from the droplet edge to the center. This magnetic microconvection from droplet edge-to-center reverses the particle transport from center-to-edge, well-known for drying droplets in the absence of external field. We use this magnetostatic microconvection to assemble secondary nonmagnetic microspheres in droplets, overwriting ring formation and direct their assembly into four distinct kinetically stable states. The method presented here offers an active control over the colloidal assembly achieved by drying sessile droplets and thus enables a new route for fabricating complex patterns and functional surface coating.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.langmuir.8b03232DOI Listing
December 2018

Were the "Pioneer" Clinical Ethics Consultants "Outsiders"? For Them, Was "Critical Distance" That Critical?

Am J Bioeth 2018 Jun;18(6):34-44

a Albany Medical College.

"Clinical ethics consultants" have been practicing in the United States for about 50 years. Most of the earliest consultants-the "pioneers"-were "outsiders" when they first appeared at patients' bedsides and in the clinic. However, if they were outsiders initially, they acclimated to the clinical setting and became "insiders" very quickly. Moreover, there was some tension between traditional academics and those doing applied ethics about whether there was sufficient "critical distance" for appropriate reflection about the complex medical ethics dilemmas of the day if one were involved in the decision making. Again, the pioneers deflected concerns by identifying and instituting safeguards to assure professional objectivity in clinical ethics consultation services. One might suggest that in moving inside and establishing normative practices, the pioneer clinical ethics consultants anticipated adoption of their routines and professionalization of the field.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/15265161.2018.1459935DOI Listing
June 2018

Spin density wave instability in a ferromagnet.

Sci Rep 2018 Mar 27;8(1):5225. Epub 2018 Mar 27.

Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA, 70803, USA.

Due to its cooperative nature, magnetic ordering involves a complex interplay between spin, charge, and lattice degrees of freedom, which can lead to strong competition between magnetic states. Binary FeGa is one such material that exhibits competing orders having a ferromagnetic (FM) ground state, an antiferromagnetic (AFM) behavior at intermediate temperatures, and a conspicuous re-entrance of the FM state at high temperature. Through a combination of neutron diffraction experiments and simulations, we have discovered that the AFM state is an incommensurate spin-density wave (ISDW) ordering generated by nesting in the spin polarized Fermi surface. These two magnetic states, FM and ISDW, are seldom observed in the same material without application of a polarizing magnetic field. To date, this unusual mechanism has never been observed and its elemental origins could have far reaching implications in many other magnetic systems that contain strong competition between these types of magnetic order. Furthermore, the competition between magnetic states results in a susceptibility to external perturbations allowing the magnetic transitions in FeGa to be controlled via temperature, magnetic field, disorder, and pressure. Thus, FeGa has potential for application in novel magnetic memory devices, such as the magnetic components of tunneling magnetoresistance spintronics devices.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-018-23555-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5869675PMC
March 2018

Predicting hidden bulk phases from surface phases in bilayered SrRuO.

Sci Rep 2017 08 31;7(1):10265. Epub 2017 Aug 31.

Center for Computation and Technology, Louisiana State University, Baton Rouge, Louisiana, 70803, USA.

The ability to predict hidden phases under extreme conditions is not only crucial to understanding and manipulating materials but it could also lead to insight into new phenomena and novel routes to synthesize new phases. This is especially true for Ruddlesden-Popper perovskite phases that possess interesting properties ranging from superconductivity and colossal magnetoresistance to photovoltaic and catalytic activities. In particular, the physical properties of the bilayer perovskite SrRuO at the surface are intimately tied to the rotation and tilt of the RuO octahedra. To take advantage of the extra degree of freedom associated with tilting we have performed first principles hybrid density functional simulations of uniaxial pressure applied along the c-axis of bulk SrRuO where we find that the octahedra become tilted, leading to two phase transitions. One is a structural transition at [Formula: see text]1.5 GPa, and the other is from a ferromagnetic (FM) metal to an antiferromagnetic (AFM) insulator at [Formula: see text]21 GPa whose AFM spin configuration is different from the AFM state near the FM ground state.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-017-10780-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5579013PMC
August 2017

Benchmarking the Fundamental Electronic Properties of small TiO Nanoclusters by GW and Coupled Cluster Theory Calculations.

J Chem Theory Comput 2017 Aug 7;13(8):3814-3828. Epub 2017 Jul 7.

Department of Chemistry, University College London , 20 Gordon Street, London WC1H 0AJ, United Kingdom.

We study the vertical and adiabatic ionization potentials and electron affinities of bare and hydroxylated TiO nanoclusters, as well as their fundamental gap and exciton binding energy values, to understand how the clusters' electronic properties change as a function of size and hydroxylation. In addition, we have employed a range of many-body methods; including GW, qsGW, EA/IP-EOM-CCSD, and DFT (B3LYP, PBE), to compare the performance and predictions of the different classes of methods. We demonstrate that, for bare clusters, all many-body methods predict the same trend with cluster size. The highest occupied and lowest unoccupied DFT orbitals follow the same trends as the electron affinity and ionization potentials predicted by the many-body methods, but are generally far too shallow and deep respectively in absolute terms. In contrast, the ΔDFT method is found to yield values in the correct energy window. However, its predictions depend upon the functional used and do not necessarily follow trends based on the many-body methods. Adiabatic potentials are predicted to be similar to their vertical counterparts and holes found to be trapped more strongly than excess electrons. The effect of hydroxylation on the clusters is to open up both the optical and fundamental gap. Finally, a simple microscopic explanation for the observed trends with cluster size and upon hydroxylation is proposed in terms of the onsite electrostatic potential.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jctc.7b00538DOI Listing
August 2017

Sperm maturation in sturgeon (Actinopterygii, Acipenseriformes): A review.

Theriogenology 2017 Jul 27;97:134-138. Epub 2017 Apr 27.

Faculty of Fisheries and Protection of Waters, University of South Bohemia in Ceske Budejovice, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Zatisi 728/II, 389 25 Vodnany, Czech Republic.

The morphology of the reproductive system of acipenseriform fishes is quite different from that of teleostean species, but an associated unique physiological difference in male sturgeons was not discovered until recently; sperm of sturgeons passes through the kidneys then via Wolffian ducts into the environment rather that emptying directly through seminal ducts. The mixing of sperm with excretory products has been found to be a requisite for the capacity to be activated (maturation step) instead of being deleterious. In the current review we summarize results of studies performed in our laboratory on physiological processes involved in sturgeon sperm maturation, namely changes in: 1) ionic environment; 2) sensitivity of spermatozoa to calcium ions (Ca); 3) antioxidant enzymes and proteolytic activities; and 4) content in macroergic phosphates arising during this maturation process. We also discuss taxa-specific aspects of sturgeon sperm maturation in relation to hormonal regulation of spermiation, and the unusual features of sturgeon sperm maturation relative to using testicular sturgeon sperm in aquaculture.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.theriogenology.2017.04.034DOI Listing
July 2017

Nontrivial Berry phase in magnetic BaMnSb semimetal.

Proc Natl Acad Sci U S A 2017 06 24;114(24):6256-6261. Epub 2017 May 24.

Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803;

The subject of topological materials has attracted immense attention in condensed-matter physics because they host new quantum states of matter containing Dirac, Majorana, or Weyl fermions. Although Majorana fermions can only exist on the surface of topological superconductors, Dirac and Weyl fermions can be realized in both 2D and 3D materials. The latter are semimetals with Dirac/Weyl cones either not tilted (type I) or tilted (type II). Although both Dirac and Weyl fermions have massless nature with the nontrivial Berry phase, the formation of Weyl fermions in 3D semimetals require either time-reversal or inversion symmetry breaking to lift degeneracy at Dirac points. Here we demonstrate experimentally that canted antiferromagnetic BaMnSb is a 3D Weyl semimetal with a 2D electronic structure. The Shubnikov-de Hass oscillations of the magnetoresistance give nearly zero effective mass with high mobility and the nontrivial Berry phase. The ordered magnetic arrangement (ferromagnetic ordering in the plane and antiferromagnetic ordering along the axis below 286 K) breaks the time-reversal symmetry, thus offering us an ideal platform to study magnetic Weyl fermions in a centrosymmetric material.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1073/pnas.1706657114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5474762PMC
June 2017

Antibacterial function of herbal extracts on growth, survival and immunoprotection in the black tiger shrimp Penaeus monodon.

Fish Shellfish Immunol 2017 Jun 29;65:52-58. Epub 2017 Mar 29.

Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Research Institute of Fish Culture and Hydrobiology, University of South Bohemia in Ceske Budejovice, Vodňany, Czech Republic; Biology Department, University of Oklahoma, Norman, OK 73019, United States.

This study examined the effects of an herbal extract composed of nine herbs i.e Aloe vera, Andrographis pariculata, Annona squamosa, Azadirachta indica, Citrus aurantifolia, Coriandrum sativum, Ocimum sanctum, Ollium cepa and Psidium guajava on growth, survival rate and immunoprotection against pathogenic Vibrio harveyi in the tiger shrimp Penaeus monodon. The petroleum ether, methanol and N-hexen extracts of different herbal plants were selected, processed and thoroughly mixed in equal proportions and added to the shrimp diets at a concentration of 1.0, 2.5 and 5.0 mL kg. After 60 days of feeding, shrimps were challenged with V. harveyi bacteria (1 × 10 cells mL), which were isolated and propagated from the infected shrimps. The shrimps fed on diets with methanolic extraction of 2.5 mL kg had significantly (P < 0.001) higher survival rate (76%), specific growth rate (4.26 ± 0.11%) and better food conversion ratio (1.5) than the other groups. This study indicates that addition of methanolic herbal extracts of 2.5 mL kg can positively influence the immune response of tiger shrimp against V. harveyi infection.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.fsi.2017.03.050DOI Listing
June 2017

Effects of dietary administration of Rose hip and Safflower on growth performance, haematological, biochemical parameters and innate immune response of Beluga, Huso huso (Linnaeus, 1758).

Fish Shellfish Immunol 2016 Dec 21;59:109-114. Epub 2016 Oct 21.

Young Researchers and Elite Club, Lahijan Branch, Islamic Azad University, Lahijan, Iran.

The aim of this study was to investigate effects of two dietary medicinal herbs, Rose hip (Rosa canina) and Safflower (Carthamus tinctorius) supplementation on growth performance, haematological, biochemical parameters and innate immune response of in juvenile beluga, Huso huso. Fish (26.3 ± 0.4 g) were allocated into 15 tanks (20 fish per tank) and triplicate groups were fed a control diet or diets containing 1% and 2% of medicinal herbs, respectively. Feed conversion ratio (FCR), specific growth rate (SGR) and condition factor (CF) did not show significant differences (P > 0.05) in fish given herbal diets. Significant differences were observed in number of white blood cells (WBC) and haemoglobin (Hb) values among the dietary treatments. The serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were significantly lower in supplemented diet groups compared with the control. Innate immune responses (lysozyme activity and ACH) were significantly higher in 2% Safflower-fed fish compared with other groups (P < 0.05). These results indicate that medicinal herbs in diets can be considered as a beneficial dietary supplement for improving the physiological parameters and enhance the immune response of Persian sturgeon.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.fsi.2016.10.033DOI Listing
December 2016

Petascale Simulations of the Morphology and the Molecular Interface of Bulk Heterojunctions.

ACS Nano 2016 07 20;10(7):7008-22. Epub 2016 Jun 20.

Center for Nanophase Materials Sciences, ‡Computer Science and Mathematics Division, §National Center for Computational Sciences, and ∥Spallation Neutron Source, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.

Understanding how additives interact and segregate within bulk heterojunction (BHJ) thin films is critical for exercising control over structure at multiple length scales and delivering improvements in photovoltaic performance. The morphological evolution of poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) blends that are commensurate with the size of a BHJ thin film is examined using petascale coarse-grained molecular dynamics simulations. Comparisons between two-component and three-component systems containing short P3HT chains as additives undergoing thermal annealing demonstrate that the short chains alter the morphology in apparently useful ways: they efficiently migrate to the P3HT/PCBM interface, increasing the P3HT domain size and interfacial area. Simulation results agree with depth profiles determined from neutron reflectometry measurements that reveal PCBM enrichment near substrate and air interfaces but a decrease in that PCBM enrichment when a small amount of short P3HT chains are integrated into the BHJ blend. Atomistic simulations of the P3HT/PCBM blend interfaces show a nonmonotonic dependence of the interfacial thickness as a function of number of repeat units in the oligomeric P3HT additive, and the thiophene rings orient parallel to the interfacial plane as they approach the PCBM domain. Using the nanoscale geometries of the P3HT oligomers, LUMO and HOMO energy levels calculated by density functional theory are found to be invariant across the donor/acceptor interface. These connections between additives, processing, and morphology at all length scales are generally useful for efforts to improve device performance.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsnano.6b03009DOI Listing
July 2016

Health Care Ethics Committees as Mediators of Social Values and the Culture of Medicine.

AMA J Ethics 2016 May 1;18(5):534-9. Epub 2016 May 1.

Professor of medicine and bioethics in the Alden March Bioethics Institute at Albany Medical College in Albany, New York, and a clinical ethics consultant at Albany Medical Center Hospital.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1001/journalofethics.2016.18.5.msoc1-1605DOI Listing
May 2016

Putting the Conversation about Gun Ownership and Safety in Context.

Authors:
Wayne Shelton

J Gen Intern Med 2016 10;31(10):1113-4

Alden March Bioethics Institute, Albany Medical College, Albany, NY, USA.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11606-016-3739-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5023603PMC
October 2016

Coupled cluster Green function: Model involving single and double excitations.

J Chem Phys 2016 Apr;144(14):144101

Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, Louisiana 70803, USA.

In this paper, we report on the development of a parallel implementation of the coupled-cluster (CC) Green function formulation (GFCC) employing single and double excitations in the cluster operator (GFCCSD). A key aspect of this work is the determination of the frequency dependent self-energy, Σ(ω). The detailed description of the underlying algorithm is provided, including approximations used that preserve the pole structure of the full GFCCSD method, thereby reducing the computational costs while maintaining an accurate character of methodology. Furthermore, for systems with strong local correlation, our formulation reveals a diagonally dominate block structure where as the non-local correlation increases, the block size increases proportionally. To demonstrate the accuracy of our approach, several examples including calculations of ionization potentials for benchmark systems are presented and compared against experiment.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1063/1.4944960DOI Listing
April 2016

The Role of Communication and Interpersonal Skills in Clinical Ethics Consultation: The Need for a Competency in Advanced Ethics Facilitation.

J Clin Ethics 2016 ;27(1):28-38

Alden March Bioethics Institute-Albany Medical College, 47 New Scotland Ave.-MC153, Albany, New York 12208 USA.

Clinical ethics consultants (CECs) often face some of the most difficult communication and interpersonal challenges that occur in hospitals, involving stressed stakeholders who express, with strong emotions, their preferences and concerns in situations of personal crisis and loss. In this article we will give examples of how much of the important work that ethics consultants perform in addressing clinical ethics conflicts is incompletely conceived and explained in the American Society of Bioethics and Humanities Core Competencies for Healthcare Ethics Consultation and the clinical ethics literature. The work to which we refer is best conceptualized as a specialized type of interviewing, in which the emotional barriers of patients and their families or surrogates can be identified and addressed in light of relevant ethical obligations and values within the context of ethics facilitation.
View Article and Find Full Text PDF

Download full-text PDF

Source
July 2016

Regression of Calcium Channel Blocker--Induced Gingival Enlargement in the Absence of Periodontal Therapy.

J Tenn Dent Assoc 2015 Fall-Winter;95(2):11-4; quiz 15-6

Aim: To illustrate the negative effect of calcium channel blocker (CCB) drugs on the gingival tissues and the reversibility of these lesions.

Case Description: The authors examined a forty-eight year-old male patient with drug-induced gingival enlargement associated with diltiazem, a CCB drug. Prior to initiating the proposed periodontal treatment, the patient was advised to consult his physician, for a possible switch to a different anti-hypertensive drug. The patient returned to the clinic three months later with a significant regression of the gingival overgrowth, which was induced by the patient ceasing the prescribed regimen without medical consultation or periodontal intervention.

Conclusion: Although CCBs are effective cardiovascular drugs, they can negatively impact the oral health by promoting gingival overgrowth in some patients. Substitution of these drugs is strongly recommended prior to any periodontal intervention in order to improve prognosis and prevent recurrence, and should be done only by the medical providers.
View Article and Find Full Text PDF

Download full-text PDF

Source
May 2016

Conduct, Oversight, and Ethical Considerations of Clinical Trials in Companion Animals with Cancer: Report of a Workshop on Best Practice Recommendations.

J Vet Intern Med 2016 Mar-Apr;30(2):527-35. Epub 2016 Mar 7.

Flint Animal Cancer Center, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO.

Development of effective and safe treatments for companion animals with cancer requires the collaboration of numerous animal health professionals and the full engagement of animal owners. Establishing 'Best Practice Recommendations' for clinical trials in veterinary oncology represents an important step toward meeting the goal of rigorous clinical trial design and conduct that is required to establish valid evidence. Likewise, optimizing patient welfare and owner education and advocacy is crucial to meet the unique ethical obligations to both owners and animals enrolled in these clinical trials and to ensure trust in the team conducting the research. To date, 'Best Practice Recommendations' for clinical trial conduct have not been reported for veterinary oncology. This document summarizes the consensus of a workshop held in November, 2014 to identify relevant ethical principles and to ensure responsible conduct of clinical research in companion animals with cancer. It is intended as a working document that will be updated as advances in science and ethical considerations require. To the extent possible, existing guidelines for the conduct and oversight of clinical trials in humans have been adapted for veterinary trials to avoid duplicative effort and to facilitate integration of clinical trials such that translational research with benefits for both companion animals and humans are encouraged.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/jvim.13916DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4913608PMC
December 2016