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# Particle physics

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#1
Shahab Boroun, Faïçal Larachi
This study investigates the response of magnetic nanoparticles (MNPs), dispersed in a viscoelastic hydrogel, to an external rotating magnetic field (RMF) for the purpose of developing a new class of magneto-responsive materials with tunable mass transport properties. Ferrogels were prepared by chemical cross-linking and polymerization of acrylamide in colloidal dispersions of thermally blocked MNPs of cobalt ferrite. Magnetization measurements of ferrogels in a swollen state revealed a transitional state from ferromagnetism to superparamagnetism through the shrinkage of hysteresis loops and the reduction of remanent magnetization...
August 16, 2017: Soft Matter
#2
Yiheng Qiu, Thomas M Henderson, Jinmo Zhao, Gustavo E Scuseria
Coupled cluster theory is the method of choice for weakly correlated systems. But in the strongly correlated regime, it faces a symmetry dilemma, where it either completely fails to describe the system or has to artificially break certain symmetries. On the other hand, projected Hartree-Fock theory captures the essential physics of many kinds of strong correlations via symmetry breaking and restoration. In this work, we combine and try to retain the merits of these two methods by applying symmetry projection to broken symmetry coupled cluster wave functions...
August 14, 2017: Journal of Chemical Physics
#3
Hsiu-Yu Yu, Zahera Jabeen, David M Eckmann, Portonovo S Ayyaswamy, Ravi Radhakrishnan
We have studied the microstructure of a flow-driven hardsphere suspension inside a cylinder using dynamical density functional theory and Monte Carlo simulations. In order to be representative of various physical conditions that may prevail in experiments, we investigate the problem using both the grand canonical ($\mu VT$) ensemble and the canonical ($NVT$) ensemble. In both ensembles, the hydrodynamic effect on the suspension mediated by the presence of the confining wall is implemented in a mean-field fashion by incorporating the thermodynamic work done by the inertial lift force on the particle given the average flow field...
August 15, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
#4
Linhan Lin, Xiaolei Peng, Zhangming Mao, Xiaoling Wei, Chong Xie, Yuebing Zheng
Directed migration of particles and molecules in a temperature gradient field, which is known as thermophoresis or the Soret effect, is of fundamental importance for mass transfer in colloid science and life sciences. However, thermophoretic tweezers that enable versatile particle manipulation have remained elusive due to the complex underlying physical forces in thermophoresis and the lack of general thermophilic particles above room temperature. Herein, we exploit entropic response and permittivity gradient at the particle-solvent interface to optically generated thermal gradient to achieve the thermophoretic trapping and dynamic manipulation of charged particles over an optothermal-responsive substrate...
August 14, 2017: Lab on a Chip
#5
Carlos J A P Martins
The observational evidence for the recent acceleration of the universe demonstrates that canonical theories of cosmology and particle physics are incomplete-if not incorrect-and that new physics is out there, waiting to be discovered. A key task for the next generation of laboratory and astrophysical facilities is to search for, identify and ultimately characterize this new physics. Here we highlight recent developments in tests of the stability of nature's fundamental couplings, which provide a direct handle on new physics: a detection of variations will be revolutionary, but even improved null results provide competitive constraints on a range of cosmological and particle physics paradigms...
August 14, 2017: Reports on Progress in Physics
#6
Neha Pandey, Renu Bhatt
Recent developments in the potential use of nanoparticles as carriers of enzyme have attracted great attention. In the present study, arsenite oxidase (AOase) enzyme capable of transforming the more toxic arsenite [As(III)] to the less toxic arsenate [As(V)] was extracted from an arsenic resistant bacterium (Exiguobacterium sp. As-9) and partially purified. Chitosan nanoparticles were prepared on the basis of ionic gelation of chitosan with tripolyphosphate (TPP) anions. The purified AOase was immobilized efficiently by physical adsorption on to chitosan nanoparticles and were characterized for particle size, morphology, zeta potential, AOase loading efficiency and in vitro transformation assay...
August 10, 2017: International Journal of Biological Macromolecules
#7
Zelalem Ayenew Worku, Dinesh Kumar, João Victor Gomes, Yunliang He, Brian Glennon, Kiran A Ramisetty, Åke C Rasmuson, Peter O'Connell, Kieran Gallagher, Trevor Woods, Nalini R Shastri, Anne-Marie Healy
The development of solid dosage forms and manufacturing processes are governed by complex physical properties of the powder and the type of pharmaceutical unit operation the manufacturing processes employs. Suitable powder flow properties and compactability are crucial bulk level properties for tablet manufacturing by direct compression. It is also generally agreed that small scale powder flow measurements can be useful to predict large scale production failure. In this study, predictive multilinear regression models were effectively developed from critical material properties to estimate static powder flow parameters from particle size distribution data for a single component and for binary systems...
August 8, 2017: International Journal of Pharmaceutics
#8
Michael Kuron, Georg Rempfer, Florian Schornbaum, Martin Bauer, Christian Godenschwager, Christian Holm, Joost de Graaf
The motion of ionic solutes and charged particles under the influence of an electric field and the ensuing hydrodynamic flow of the underlying solvent is ubiquitous in aqueous colloidal suspensions. The physics of such systems is described by a coupled set of differential equations, along with boundary conditions, collectively referred to as the electrokinetic equations. Capuani et al. [J. Chem. Phys. 121, 973 (2004)] introduced a lattice-based method for solving this system of equations, which builds upon the lattice Boltzmann algorithm for the simulation of hydrodynamic flow and exploits computational locality...
December 7, 2016: Journal of Chemical Physics
#9
G Zhang, F H Stillinger, S Torquato
The probability of finding a spherical cavity or "hole" of arbitrarily large size in typical disordered many-particle systems in the infinite-system-size limit (e.g., equilibrium liquid states) is non-zero. Such "hole" statistics are intimately linked to the thermodynamic and nonequilibrium physical properties of the system. Disordered "stealthy" many-particle configurations in d-dimensional Euclidean space [Doublestruck R](d) are exotic amorphous states of matter that lie between a liquid and crystal that prohibit single-scattering events for a range of wave vectors and possess no Bragg peaks [Torquato et al...
August 11, 2017: Soft Matter
#10
A Darras, E Opsomer, N Vandewalle, G Lumay
The influence of a magnetic field on the aggregation process of superparamagnetic colloids has been well known on short time for a few decades. However, the influence of important parameters, such as viscosity of the liquid, has received only little attention. Moreover, the equilibrium state reached after a long time is still challenging on some aspects. Indeed, recent experimental measurements show deviations from pure analytical models in extreme conditions. Furthermore, current simulations would require several years of computing time to reach equilibrium state under those conditions...
August 10, 2017: Scientific Reports
#11
J Cai, J P Townsend, T C Dodson, P A Heiney, A M Sweeney
A parabolic relationship between lens radius and refractive index allows spherical lenses to avoid spherical aberration. We show that in squid, patchy colloidal physics resulted from an evolutionary radiation of globular S-crystallin proteins. Small-angle x-ray scattering experiments on lens tissue show colloidal gels of S-crystallins at all radial positions. Sparse lens materials form via low-valence linkages between disordered loops protruding from the protein surface. The loops are polydisperse and bind via a set of hydrogen bonds between disordered side chains...
August 11, 2017: Science
#12
Yuxin Wang, Guang Cheng, See Leng Tay, Yunxia Guo, Xin Sun, Wei Gao
In this study we investigated the effects of Bi addition on the microstructure and mechanical properties of an electrodeposited nanocrystalline Ag coating. Microstructural features were investigated with transmission electron microscopy (TEM). The results indicate that the addition of Bi introduced nanometer-scale Ag-Bi solid solution particles and more internal defects to the initial Ag microstructures. The anisotropic elastic-plastic properties of the Ag nanocrystalline coating with and without Bi addition were examined with nanoindentation experiments in conjunction with the recently-developed inverse method...
August 10, 2017: Materials
#13
Hang Yao, Junpei Kang, Weichang Li, Jian Liu, Renjian Xie, Yingjun Wang, Sa Liu, Dong An Wang, Li Ren
Cartilage repairing graft had been widely studied and the osteochondral replacement hydrogels were proved to be an excellent method in research and clinical. However, it was difficult to solve three main issues in osteochondral replacement preparation at one time: surface lubrication, overall mechanical support and good simulations of cell regeneration. A novel integrated bilayered hydrogel osteochondral replacement was constructed by blending polyvinyl alcohol (PVA) and β-tricalcium phosphate (β-TCP) in this study...
August 9, 2017: Biomedical Materials
#14
N K G Salama, A C Dale, V V Ivanov, P F Cook, C C Pert, C M Collins, B Rabe
Sea lice are a constraint on the sustainable growth of Scottish marine salmonid aquaculture. As part of an integrated pest management approach, farms coordinate procedures within spatial units. We present observations of copepodids being at relatively greater density than nauplii in upper waters, which informs the development of surface layer sea lice transmission modelling of Loch Linnhe, Scotland, for informing farm parasite management. A hydrodynamic model is coupled with a biological particle-tracking model, with characteristics of plankton sea lice...
August 7, 2017: Journal of Fish Diseases
#15
Gabriele Barbosa Torres, Tânia Mara da Silva, Rosanna Tarkany Basting, Enrico Coser Bridi, Fabiana Mantovani Gomes França, Cecilia Pedroso Turssi, Flávia Lucisano Botelho do Amaral, Sérgio Eduardo de Paiva Gonçalves, Roberta Tarkany Basting
OBJECTIVES: To evaluate the bond strength to superficial (SD) and deep (DD) dentin after the use of 2.5% (T2.5%) or 4% (T4%) titanium tetrafluoride (TiF4) in aqueous solution as a dentin pretreatment, or when incorporated into the primer (T2.5%P and T4%P) of an adhesive system (Clearfil SE Bond/CL). Degree of conversion (DC), particle size (PS), polydispersity index (PI) and zeta potential (ZP) of the solutions were evaluated. METHODS: Fifty molars were sectioned longitudinally to obtain two slices of each tooth, which were demarcated into SD and DD...
August 3, 2017: Dental Materials: Official Publication of the Academy of Dental Materials
#16
REVIEW
Dong-Xia Feng, Anh V Nguyen
The floatability of solid particles on the water surface governs many natural phenomena and industrial processes including film flotation and froth flotation separation of coal and valuable minerals. For many years, the contact angle (CA) has been postulated as the key factor in determining the particle floatability. Indeed, the maximum force (tenacity) supporting the flotation of fine spheres was conjectured to occur when the apical angle of the contact circle is equal to the contact angle. In this paper, the model predictions are reviewed and compared with experimental results...
July 28, 2017: Advances in Colloid and Interface Science
#17
Ratan K Mishra, Martin Weibel, Thomas Müller, Hendrik Heinz, Robert J Flatt
We present our research findings related to new formulations of the organic additives (grinding aids) needed for the efficient grinding of inorganic solids. Even though the size reduction phenomena of the inorganic solid particles in a ball mill is purely a physical process, the addition of grinding aids in milling media introduces a complex physicochemical process. In addition to further gain in productivity, the organic additive helps to reduce the energy needed for grinding, which in the case of cement clinker has major environmental implications worldwide...
August 9, 2017: Chimia
#18
M Fabbrichesi, E Gabrielli, B Mele
If dark photons are massless, they couple to standard-model particles only via higher dimensional operators, while direct (renormalizable) interactions induced by kinetic mixing, which motivates most of the current experimental searches, are absent. We consider the effect of possible flavor-changing magnetic-dipole couplings of massless dark photons in kaon physics. In particular, we study the branching ratio for the process K^{+}→π^{+}π^{0}γ[over ¯] with a simplified-model approach, assuming the chiral quark model to evaluate the hadronic matrix element...
July 21, 2017: Physical Review Letters
#19
Yu Huang, Aijun Li, Chaoying Qiu, YingLai Teng, Yong Wang
This research studies the in-depth characteristics including the binding interactions and morphological structure of tannic acid (TA)/grape seed proanthocyanidins (GSP) and gelatin (GLT) colloidal complexes, and evaluated the stability and lipid oxidation of emulsions formed by the colloidal complexes. Polyphenol and GLT (1.2 wt%) self-assembled complexes were fabricated by varying the mass ratio (1 : 16, 1 : 8 and 1 : 4) and pH in the range of 3-7. TA and GSP can form stable colloidal complexes with GLT at the nanoscale at pH 6, as shown by the particle size results, and the complexes exhibited a spherical morphology as seen by transmission electron microscopy...
August 4, 2017: Food & Function
#20
Amr ElShaer, Ali Al-Khattawi, Afzal R Mohammed, Monika Warzecha, Dimitrios A Lamprou, Hany Hassanin
The fast development in materials science has resulted in the emergence of new pharmaceutical materials with superior physical and mechanical properties. Low-substituted hydroxypropyl cellulose is an ether derivative of cellulose and is praised for its multi-functionality as a binder, disintegrant, film coating agent and as a suitable material for medical dressings. Nevertheless, very little is known about the compaction behaviour of this polymer. The aim of the current study was to evaluate the compaction and disintegration behaviour of four grades of L-HPC namely; LH32, LH21, LH11 and LHB1...
August 4, 2017: Pharmaceutical Development and Technology
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