Minor Bands Research Articles

Adaptive single-phase autoreclosing of high-voltage transmission lines based on steady-state parameters

Conventional adaptive single-phase autoreclosing (ASPAR) of extra-high-voltage transmission lines that uses the RMS voltage on the disconnected phase as the information-bearing parameter may have a dead band when high power is transmitted via the transmission line. This is caused by excess voltage during arcing after the arc extinction. The line end voltage under grounding arcing is determined predominantly by the longitudinal emf induced by the currents in the healthy phase. At the limit power-transmission angles, this voltage exceeds the recovery voltage after extinction of the secondary arc, which does not allow monitoring the status of the arc by the voltage. Using simple mathematical models, the existence of dead bands for both uncompensated and shunt-compensated lines (using four- or three-beam reactors) is shown. To establish the secondary arc extinction, it is proposed to monitor the voltage phase. The feasibility of the “phase” method was studied using a transmission line model based on matrix n-poles. The model considers the wire transposition and the nonlinearity of the grounding arc. Fundamentally, the phase method does not have any dead bands; however, owing to low arc channel conductance, a minor dead band may occur at large transmission angles and short circuits near the side of the voltage measurement. The restrictions to application of the “phase” method to the ASPAR are established and its typical dead band is identified.

Resolución de enigmas geológicos e históricos utilizando técnicas gemológicas avanzadas: Caso del ópalo noble de Franco Dávila (1772)

Un gran ópalo noble de 33 gramos engastado en montura de plata dorada está expuesto al público en el Museo Nacional de Ciencias Naturales (MNCN). Esta pieza histórica está documentada en su propia montura (año 1772), en el legajo 775 del Archivo del Museo y en la muestra 395 del Catálogo de muestras de Pedro Franco Dávila. Su patrón de difracción de rayos X (DRX) es muy parecido al de otros ópalos de origen volcánico y contiene cantidades variables de cristobalita, tridimita y sílice amorfa. El espectro Raman muestra una banda con picos a 242, 343 y 416 cm-1 asociados a deformaciones O-Si-O; otra con picos a 780 y 819 cm-1 de vibraciones de tensión simétricas O-Si-O de anillos de 3 y 4 eslabones y otras menores. El espectro Raman es similar a los de ópalos mexicanos de origen volcánico y muestra una banda con nodos de tensión v1 (OH) a 3233, 3393, 3511, 3628 cm-1 relacionados con grupos OH con enlaces de hidrógeno con grupos silanoles aislados. Mediante microscopía dual confocal interferométrica 3D (MCI3D), que es una técnica no destructiva de alta resolución y tecnología LED, se desvela la geometría de grabado del buril sobre la montura mientras que la tomografía computerizada de rayos X destaca la talla cuadrada de tipo carre-princesa y los rellenos de AgCl de una fisura. Bajo microscopia electrónica de barrido ambiental (MEBA) se han observado baritinas, filoncillos de sílice enriquecida en Mn y elevados contenidos de Al y K. Estos datos, junto con la información histórica sugieren que la pieza procede de los yacimientos históricos de ópalos encajados en andesitas de Eslovaquia y explican la compleja óptica del cabujón. El marco de Ag tiene Hg y AgCl que indican su extracción por amalgama; además tiene Ag2S que podría provenir de Nueva España, entonces (año 1772) en plena producción de plata. La asociación de varias técnicas analíticas no-destructivas preserva la integridad de esta pieza histórica aportando datos analíticos significativos que permiten deducir procesos genéticos de minerales, procedencias y técnicas de manufactura de materiales. Todo ello facilita la caracterización, interpretación, conservación y valorización del patrimonio cultural y arqueológico.

Substrate-Induced Carbon Monoxide Reactivity Suggests Multiple Enzyme Conformations at the Catalytic Copper M-Center of Peptidylglycine Monooxygenase.

The present study uses CO as a surrogate for oxygen to probe how substrate binding triggers oxygen activation in peptidylglycine monooygenase (PHM). Infrared stretching frequencies (ν(C ≡ O)) of the carbonyl (CO) adducts of copper proteins are sensitive markers of Cu(I) coordination and are useful in probing oxygen reactivity because the electronic properties of O2 and CO are similar. The carbonyl chemistry has been explored using PHM WT and a number of active site variants in the absence and presence of peptidyl substrates. We have determined that upon carbonylation (i) a major CO band at 2092 cm-1 and a second minor CO band at 2063 cm-1 are observed in the absence of peptide substrate Ac-YVG; (ii) the presence of peptide substrate amplifies the minor CO band and causes it to partially interconvert with the CO band at 2092 cm-1; (iii) the substrate-induced CO band is associated with a second conformer at CuM; and (iv) the CuH-site mutants, which are inactive, fail to generate any substrate-induced CO bands. The total intensity of both bands is constant, suggesting that the Cu(I)M-site partitions between the two carbonylated enzyme states. Together, these data provide evidence for two conformers at CuM, one of which is induced by binding of the peptide substrate with the implication that this represents the conformation that also allows binding and activation of O2.

Genetic variation and relationships of old maize genotypes (Zea mays L.) detected using SDS-page

The assessment of genetic diversity among the members of a species is of vital importance for successful breeding and adaptability. In the present study 40 old genotypes of maize from Hungary, Union of Soviet Socialist Republics, Poland, Czechoslovakia, Yugoslavia and Slovak Republic were evaluated for the total seed storage proteins using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) through vertical slab unit. The number of total scorable protein bands was twentythree as a result of SDS-PAGE technique but those that were not cosistent in reproducibility and showed occasional variation in sharpness and density were not considered. Out of twentythree polypeptide bands, 6 (31%) were commonly present in all accessions and considered as monomorphic, while 17 (65%) showed variations and considered as polymorphic. On the basis of banding profiles of proteins of different kDa, gel was divided into zones A, B and C. The major protein bands were lied in zones A and B, while minor bands were present in zones C. In zone A out of 10 protein bands, 1 were monomorphic and 9 were polymorphic. In zone B out of 8 protein bands, 3 was monomorphic and 5 was polymorphic and in zone C out of 5 protein bands, 2 were monomorphic whereas 3 polymorphic. The dendrogram tree demonstrated the relationship among the forty registered old maize genotypes according to the similarity index, using UPGMA cluster analysis. The dendrogram was divided into two main clusters. The first one contained eleven genotypes from maize, while the second cluster contained the twentynine genotypes of maize. Similarly the present study of genetic variability in the seed storage polypeptide determined by SDS-PAGE technique proved that it is fruitful to identify genetic diversity among accessions of maize.

Epitaxial growth of thermally stable cobalt films on Au(111)

Ferromagnetic thin films play a fundamental role in spintronic applications as a source for spin polarized carriers and in fundamental studies as ferromagnetic substrates. However, it is challenging to produce such metallic films with high structural quality and chemical purity on single crystalline substrates since the diffusion barrier across the metal-metal interface is usually smaller than the thermal activation energy necessary for smooth surface morphologies. Here, we introduce epitaxial thin Co films grown on an Au(111) single crystal surface as a thermally stable ferromagnetic thin film. Our structural investigations reveal an identical growth of thin Co/Au(111) films compared to Co bulk single crystals with large monoatomic Co terraces with an average width of 500 Å, formed after thermal annealing at 575 K. Combining our results from photoemission and Auger electron spectroscopy, we provide evidence that no significant diffusion of Au into the near surface region of the Co film takes place for this temperature and that no Au capping layer is formed on top of Co films. Furthermore, we show that the electronic valence band is dominated by a strong spectral contribution from a Co 3d band and a Co derived surface resonance in the minority band. Both states lead to an overall negative spin polarization at the Fermi energy.

The electronic structure and half-metallic properties of zincblende TiBi (001) surfaces and TiBi(001)/InSb(001) interface

Abstract First principles calculations were performed using full potential linearized augmented plane wave (FPLAPW) method based on density functional theory (DFT) to study bulk TiBi in rock salt (RS), hexagonal NiAs, and zincblende (ZB) structures, free (001) surfaces of ZB TiBi, and interface of ZB TiBi with InSb(001). The nonmagnetic NiAs structure was ground state structure of bulk TiBi and nonmagnetic RS and ferromagnetic ZB structures were introduced as metastable structures. It was found that ZB TiBi is a half-metallic (HM) ferromagnet with a minority band gap of about 1.43 eV. The origin of half-metallicity was also discussed. The obtained phase diagram showed more stability of the Bi (001) terminated surface compared with the Ti (001) termination. The Ti (001) termination keeps HM property, while half-metallicity was destroyed at Bi (001) termination. The ZB TiBi/InSb (001) interface revealed HM property showing that InSb semiconductor is a suitable substrate for growing ZB TiBi in spintronics.

Structural and Magnetic Study on the Effect of Substitution of Cobalt by d-Valent Elements of Co<sub>2</sub>FeSi Heusler Alloy

In this paper, the effect of substitution of Co by d-valent elements such as Ag and Pt on electronic structure and magnetic properties of full Heusler type Co2FeSi alloys was investigated. Structural study reveals the presence of a small gap in the minority band structure around the vicinity of the Fermi level on Co2FeSi resulting to half-metallic behaviour. However, CoFeSiAg and CoFeSiPt cannot preserved the half-metalicity due to disappearing of the gap in the minority band structure due to the creation of new states around the Fermi level in the minority density of states. The variation in the magnetic moment of Co2FeSi with change of the atoms was attributed to the change in the local magnetic moment of atoms.

Structural, electronic and magnetic properties of CoFeTiGa1−xSbx compounds

Structural, electronic and magnetic properties of Heusler compounds CoFeTiGa1−xSbx have been studied. X-ray diffraction patterns show that CoFeTiGa1−xSbx (x=0.25, 0.5, 0.75, 1) crystallize into LiMgPdSn-type structure. First-principles calculations indicate that CoFeTiGa1−xSbx (x=0.25, 0.5, 0.75, 1) are half-metal with considerable minority band gaps. The substitution of Sb for Ga gives rise to the spin moments of the compounds, and makes them to be half-metallic ferrimagnets.

Characterization of glycoproteins expressing the blood group H type 1 epitope on human induced pluripotent stem (hiPS) cells.

Recently, we established two mouse monoclonal antibodies (R-10G and R-17F). The R-17F antibody (IgG1 subtype) exhibited a strong cytotoxic effect on hiPS/ES cells. The R-17F antigen isolated from a total lipid extract of hiPS (Tic) cells was identified as LNFP I (Fucα1-2Galβ1-3GlcNAcβ1-3Galβ1-4Glc). In the present study, R-17F binding proteins were isolated from hiPS (Tic) cell lysates with an affinity column of R-17F. They gave one major R-17F positive band around 250kDa, and several minor bands between 150kDa and 25kDa. The former band was identified as podocalyxin by LC/MS/MS after SDS-PAGE. Hapten inhibition studies on R-17F binding to R-17F column-purified proteins with various synthetic oligosaccharides revealed that the blood group H type 1 triaose structure (Fucα1-2Galβ1-3GlcNAc) was the predominant epitope on all the R-17F binding proteins. These bands disappeared completely on digestion with α1-2 fucosidase, but not with α1-3/4 fucosidase. Upon PNGase F digestion, the R-17F positive band around and above 250kDa did not show any change, while the minor bands between 150kDa and 25kDa disappeared completely, suggesting that the epitope is expressed on N-glycans in the latter and probably on O-glycans in the former. These results, together with those obtained in our previous studies on R-10G (Kawabe et al. Glycobiology, 23, 322-336 (2013)), indicated that both R-10G and R-17F epitopes are carried on the same podocalyxin molecule. The R-17F epitopes on these glycoproteins expressed on hiPS cells could be associated with the molecular mechanism underlying the carbohydrate-mediated cytotoxic activity of R-17F.

Electronic and magnetic properties of X2YZ and XYZ Heusler compounds: a comparative study of density functional theory with different exchange-correlation potentials

The electronic and magnetic properties of Heusler compounds X2YZ and XYZ (X = Co, Ni, Pt, Fe; Y = Mn, Cr, Vi; Z = Al, Sb, Ga) are investigated by using the density functional theory with generalized gradient approximation (GGA), GGA plus U (LSDA+U), and modified Becke−Johnson (mBJ) exchange potential. It is found that the half-metallic gaps are generally widened reasonably by LSDA+U and mBJ as compared to the conventional GGA. For the Co-based Heusler compounds the inclusion of U in GGA leads to a larger minority band gap while it is destroyed for Fe2VAl and NiMnSb. The magnetic properties of Co2VSi and Co2VSn are well defined within LSDA+U and mBJ with an exact integer value of magnetic moment. The band gaps of Fe2VAl and CoMnSb given by mBJ are in good agreement with the available experimental data of x-ray absorption spectroscopy. Except for the reasonably larger band gap, the mBJ band structure is almost same as that of GGA but is remarkably different from that of LSDA+U.

Half-metallicity in the inverse Heusler Ti2RuSn alloy: A first-principles prediction

The electronic and magnetic properties of the Ti2RuSn Heusler compound are investigated by means of ab initio calculations with the full-potential linearized augmented plane wave (FLAPW) method. The generalized gradient approximation (GGA) method is used for the calculations. The CuHg2Ti-type structure is energetically more stable than the AlCu2Mn-type structure. The inverse-Heusler Ti2RuSn represents half-metallic behavior. The total spin moment of the compound is 2μB which coincides with the Slater–Pauling rule of Mt=Zt−18 with the equilibrium lattice constant a0=6.44Å and the strained lattice constants as well. The majority bands have metallic properties, but the minority bands have semiconductor properties with a gap of 0.35eV, and the spin-flip gap is 0.23eV. Moreover, the sensitivity of half-metallicity is investigated under two types of structural distortion, namely uniform strain and tetragonal distortion.

Fluence-dependent dynamics of the 5d6s exchange splitting in Gd metal after femtosecond laser excitation

We investigate the fluence-dependent dynamics of the exchange-split 5d6s valence bands of Gd metal after femtosecond, near-infrared (IR) laser excitation. Time- and angle-resolved photoelectron spectroscopy (tr-ARPES) with extreme ultraviolet (XUV) probe pulses is used to simultaneously map the transient binding energies of the minority and majority spin valence bands. The decay constant of the exchange splitting increases with fluence. This reflects the slower response of the occupied majority-spin component, which we attribute to Elliot–Yafet spin-flip scattering in accordance with the microscopic three-temperature model (M3TM). In contrast, the time constant of the partly unoccupied minority-spin band stays unaffected by a change in pump fluence. Here, we introduce as an alternative to superdiffusive spin transport exchange scattering, which is an ultrafast electronic mechanism explaining the observed dynamics. Exchange scattering can reduce the spin polarization in the partially unoccupied minority-spin band and thus its energetic position without effective demagnetization.

First-principles study of structural, elastic, thermodynamic, electronic and magnetic properties for the quaternary Heusler alloys CoRuFeZ (Z = Si, Ge, Sn)

The electronic structure and magnetic properties of CoRuFeZ (Z = Si, Ge, and Sn) quaternary Heusler compounds were investigated using the full-potential linearized augmented plane wave (FPLAPW) method in framework of the density functional theory (DFT). The results showed that CoRuFeZ (Z = Si, Ge, and Sn) compounds were stable in Y-type1 structure. By use the GGA-mBJ, the CoRuFeGe and CoRuFeSn compounds were true half-metallic (HM) ferromagnets. The CoRuFeSi had a nearly HM characteristic. The minority band gaps were 0.557 eV, 0.444 eV and 0.428 eV for CoRuFeSi, CoRuFeGe and CoRuFeSn, respectively. The total magnetic moments of CoRuFeGe and CoRuFeSn compounds were obtained 5 μB per formula unit, which were in agreement with Slater-Pauling rule Mtot = (Ztot − 24). CoFeTiSi alloy can transform from a nearly half-metallic to a half-metallic alloy by employing a little expansion stress (+1.725% relatively to the equilibrium lattice constant a0). The half-metalliciy characteristic exists in relatively wide ranges of 5.9–6.9 Å, 5.825–6.063 Å and 5.921–7.187 Å for CoRuFeSi, CoRuFeGe and CoRuFeSn compounds, respectively, which makes them promising candidates in spintronics.

Tunable optical properties of silymarin flavonolignans

Abstract Exposure to UV radiation leads to several skin disorders. In particular, this can be attributed to an increase of the rate of DNA mutations, either due to direct absorption by proteins and DNA (mainly UVB), or due to ROS generation (mainly UVA). The plant extract silymarin is a promising sunscreen agent. It contains numerous flavonolignans and other polyphenol derivatives. In this joint experimental and theoretical study, we focus on silybin (SB), silychristin (SCH), silydianin (SD), and their 2,3-dehydroderivatives (DHSB, DHSCH, DHSD) and we describe their UV/Vis absorption properties, particularly the pH-dependence. Under acidic conditions, SB, SCH and SD exhibit a main and a minor absorption band in the UVB and UVA regions, respectively. The deprotonation in basic environment reverses this trend, making the UVA-absorption band predominant. The dehydrogenation of the C2-C3 bond (DHSB, DHSCH and DHSD) also shifts the main absorption band in the UVA region in acidic environment. In this case, basic environment causes further bathochromic shift, and the absorption band lies in the Vis region. A solvatochromic analysis revealed that, whereas the protonated forms are rather insensitive to other environmental factors, absorption properties of the deprotonated compounds strongly depend on intermolecular hydrogen bonding with solvent molecules. The time-dependent density functional theory (TD-DFT) calculations and molecular orbital analysis rationalized these effects.

Ultrafast reduction of exchange splitting in ferromagnetic nickel

A decade ago Rhie et al (2003 Phys. Rev. Lett. 90 247201) reported that when ferromagnetic nickel is subject to an intense ultrashort laser pulse, its exchange splitting is reduced quickly. But to simulate such reduction remains a big challenge. The popular rigid band approximation (RBA), where both the band structure and the exchange splitting are held fixed before and after laser excitation, is unsuitable for this purpose, while the time-dependent density functional theory could be time-consuming. To overcome these difficulties, we propose a time-dependent Liouville and density functional theory (TDLDFT) that integrates the time-dependent Liouville equation into the density functional theory. As a result, the excited charge density is reiterated back into the Kohn–Sham equation, and the band structure is allowed to change dynamically. Even with the ground-state density functional, a larger demagnetization than RBA is found; after we expand Ortenzi’s spin scaling method into an excited-state (laser) density functional, we find that the exchange splitting is indeed strongly reduced, as seen in the experiment. Both the majority and minority bands are shifted toward the Fermi level, but the majority shifts a lot more. The ultrafast reduction in exchange splitting occurs concomitantly with demagnetization. While our current theory is still unable to yield the same percentage loss in the spin moment as observed in the experiment, it predicts a correct trend that agrees with the experiments. With a better functional, we believe that our results can be further improved.

Temperature-dependence of current-perpendicular-to-the-plane giant magnetoresistance spin-valves using Co2(Mn1−xFex)Ge Heusler alloys

The properties of Co2(Mn1−xFex)Ge (CMFG) (x = 0–0.4) Heusler alloy magnetic layers within polycrystalline current-perpendicular-to-the plane giant magnetoresistance (CPP-GMR) spin-valves are investigated. CMFG films annealed at 220–320 °C exhibit partly ordered B2 structure with an order parameter SB2 = 0.3–0.4, and a lower SB2 was found for a higher Fe content. Nevertheless, CPP-GMR spin-valve devices exhibit a relatively high magnetoresistance ratio of ∼13% and a magnetoresistance-area product (ΔRA) of ∼6 mΩ μm2 at room temperature, which is almost independent of the Fe content in the CMFG films. By contrast, at low temperatures, ΔRA clearly increases with higher Fe content, despite the lower B2 ordering for increasing the Fe content. Indeed, first-principles calculations reveal that the CMFG alloy with a partially disordered B2 structure has a greater density of d-state at the Fermi level in the minority band compared to the Fe-free (Co2MnGe) alloy. This could explain the larger ΔRA measured on CMFG at low temperatures by assuming that s-d scattering mainly determines the spin asymmetry of resistivity as described in Mott's theory.

Compositional variation and palaeoenvironment of the volcanolithic Fort Cooper Coal Measures, Bowen Basin, Australia

An integrated analysis of megascopic lithotype, microscopic maceral and mineral composition, stable carbon isotope and interburden sedimentology from a single well was used to interpret the response of the Late Permian Fort Cooper Coal Measures (FCCM) to regional and global environmental influences. The FCCM are differentiated from underlying, relatively high vitrinite Moranbah Coal Measures, and overlying higher inertinite Rangal Coal Measures in the Bowen Basin by their intercalation with abundant tuff and siliciclastic partings and interbeds. Besides this, there is little described about the variation in the organic composition of the FCCM and its causes. The FCCM can be subdivided into a lower aggradational Fair Hill Formation, transgressed by the shallow marine-derived Black Alley Shale that interfinger with/is overlain by the progradational Middle Main Seams and Burngrove Formation coal measures. The coals are dominantly dull with minor bright bands that are more abundant in the Burngrove Formation representing a change in plant composition. The maceral analysis shows that the coals in the Fair Hill Formation and Middle Main Seams are vitrinite-rich (80–90% mmf) albeit with high mineral matter suggesting the formation of precursory peat under rising water levels and with high sediment (tuff) influx and preservation. The coals in the Burngrove Formation have an increased inertinite content (30% mmf) but are also high in mineral matter suggesting a shift to increased decomposition arising from a fluctuating water table, possibly increased aridity and/or microbial activity. Tuffs occur throughout, and although their frequency is higher in the lower Fair Hill Formation, the preservation of thicker tuffs in the upper Burngrove Formation indicates increased intensity of volcanism that could have modified the environment. Variation in carbon isotope compositions show a parabolic trend, from around −24.1‰ in the Fair Hill Formation to more variable values in the Middle Main Seams with an overall 13C-enrichment upwards in the Burngrove Formation, prior to the δ13C values becoming negative (depleted between −1 to −4% from the average −24.1‰) in the top seams and into the overlying Rangal Coal Measures. The 13C-depletion trend in the upper part of the section is unexpected in view of corresponding increase in inertinite content of the coals indicating that the δ13C values/plant composition and inertinite content are decoupled, unless the inertinite origin is from intense microbial decay. Similar stable carbon isotope depletion trends have been observed elsewhere in an equivalent stratigraphic interval of the Bowen Basin suggesting that the carbon isotope values are responding to global conditions that cause negative excursions in carbon isotopes before the P-T boundary. Overall, the basin was continuously subsiding and peats accumulated with constant interruptions from excessive sedimentation and volcanic eruptions. The low proportion of visible thick bright bands coupled with high telovitrinite (mmf) content suggests a marsh to fen environment, with an open canopy and ponding able to preserve volcanic ash falls.

Over 9% Efficient Kesterite Cu2ZnSnS4 Solar Cell Fabricated by Using Zn1–xCdxS Buffer Layer

A kesterite Cu2ZnSnS4 thin film solar cell with efficiency of over 9% is obtained by utilizing Zn1–xCdxS film as a replacement to traditional CdS buffer layer. Zn1–xCdxS film can optimize the conduction band offset between Cu2ZnSnS4 absorber and buffer, forming a minor positive conduction band alignment, thereby alleviating the recombination significantly and improving the open circuit voltage and fill factor efficiently.

The first report on coagulation and phospholipase A2 activities of Persian Gulf lionfish, Pterois russelli, an Iranian venomous fish

Pterois russelli is a venomous fish belonging to scorpionidae family. Regarding to high significance value for tracing potential therapeutic molecules and special agents from venomous marine creatures, the present study was aimed to characterization of the Persian Gulf lionfish venom.Proteolytic, phospholipase, hemolytic, coagulation, edematogenic and dermonecrotic activities were determined for extracted venom. The LD50 of P. russelli venom was determined by intravenous injection in white Balb/c mice.Phospholipase A2 activity was recorded at 20 μg of total venom. Coagulation activity on human plasma was shown by Prothrombin Time (PT) and activated Partial Thromboplastin Time (APTT) assays and coagulation visualized after 7 and 14 s respectively for 60 μg of crude venom. LD50 was calculated as 10.5 mg/kg. SDS-PAGE revealed the presence of major and minor protein bands between 6 and 205 kDa. Different amounts of crude venom ranged from 1.87 to 30 μg showed proteolytic activity on casein. The highest edematic activity was detected at 20 μg. Our findings showed that the edematic activity was dose dependent and persisted for 48 h after injection. The crude venom did not induce dermonecrotic activity on rabbit skin and showed no hemolytic activity on human, mouse and rabbit erythrocytes.This is the first report for phospholipase A2 and coagulation activity in venomous fish and venomous marine animals respectively. Proteolytic activity of P. russelli venom is in accordance with the other genara of scorpionidae family. According to venom activity on intrinsic and extrinsic coagulation pathways, lionfish venom would be contained an interesting pharmaceutical agent. This study is pending to further characterization of phospholipase A2, coagulation, and protease activities and also in vivo activity on animal model of surface and internal bleeding.

The influence of particle rolling and imperfections on the formation of shear bands in granular material

This paper examines the development and evolution of shear bands in granular assemblies when particle rolling and imperfections are taken into account. Simulated biaxial tests in two-dimension are conducted using the discrete element method. The progressive development of rotational angles and effective strain are presented to describe the emergence and evolution of shear bands in biaxial tests. The simulated results reveal that when rolling resistance is taken into account in DEM, the development of shear bands is more distinct as the evolution of the minor shear bands is limited while the major shear bands are preferably promoted in granular materials, and that the local rotating bearings not only influence the onset of shear bands and the width of the shear bands, but also decrease the resistance and reduce the strength of the granular material. Also, it is demonstrated that the primary shear bands initiate from the imperfect areas and develop preferentially along the direction of imperfections. Therefore, the emergence and development of shear bands, which will result in a decline in strength and eventually lead to instability and destruction of the material, can be effectively simulated when rolling resistance is incorporated in DEM and the initial distribution of imperfections in the granular material is defined.