Spike Formation Research Articles

45 keV N5+ ions induced spikes on CdS thin films: Morphological, structural and optical properties

CBD grown CdS thin films were implanted using 45 keV N5+ ions of different fluences from 1 × 1015 to 5 × 1016 ions/cm2 by electron cyclotron resonance (ECR) ion source. Structural properties of pristine and ion beam implanted films were studied by glancing angle X-ray diffraction (GAXRD) and it becomes a hexagonal structure of polycrystalline thin films. High resolution scanning electron microscopy (HRSEM) studies shows that the pristine sample forms agglomerated particles of CdS. After ion implantation of higher fluence 5 × 1016 ions/cm2, numerous defects created spikes on the surface of the film. The spike formation explained with the help of nuclear elastic collisions. The optical band gap energy of N5+ ion implanted thin films was reduced with increases of ion fluences. This is probably due to lattice disorder produced band-tailing and/or creation of impurity states. The red, yellow, green and band edge emissions were studied in correspondence with photoluminescence spectrum.

Study on transient emission spikes reduction of a heavy-duty diesel engine equipped with a variable intake valve closing timing mechanism and a two-stage turbocharger

The overall performance and emission during a speed/torque versus time transient cycle are investigated in a heavy-duty truck engine equipped with an intake valve closing timing mechanism and a two-stage turbocharger system (high-pressure turbine is variable geometry turbine). The performance discrepancy analysis between steady-state and transient operation is completed based on a fairly optimized steady-state baseline. The result shows that during the transient operation, the transient NOx emission can track the steady-state baselines much better than particle matter, and the cumulative NOx in transients is even lower than the cumulative NOx of the steady-state baselines, while the rising particle matter emissions mainly due to appearance in particle matter emission spikes during the cycle. And the transient particle matter spikes appeared almost in two typical transient conditions: sharp acceleration from idling and abrupt load transients. The instantaneous equivalence ratio (Φ) is found to be the main physical factor governing particle matter spikes formation in transients. Particle matter spikes become prominent when Φ cannot track the steady-state baseline well or Φ rises over a critical value of 0.8. The control strategy of intake valve closing timing mechanism-variable geometry turbine-exhaust gas recirculation to bridge the gap of Φ between the steady-state and the transients has been established, which effectively cut down the emission spikes, reducing particle matter emissions by 32.9% with almost no change in NOx.

Effect of Azospirillum brasilense Sp245 Lipopolysaccharides on Wheat Plant Development

Lipopolysaccharides (LPS) are integral and essential constituents of the outer membranes of Gram-negative bacteria that have been extensively investigated in relation to the activation of plant defense responses. In the present study, we evaluated the effect of exogenously applied Azospirillum brasilense LPS on wheat plant development, including plant aging, spike formation and size, as well as grain yield and grain chemical composition. Experiments were performed in plants cultivated in pots under greenhouse conditions. Plants were sprayed with two LPS concentrations (2 and 5 µg/mL) once a week over 3 months. LPS administration increased leaf length, especially the second leaf. Although spike formation was accelerated, spike length was reduced compared to untreated controls, and both responses were dependent on LPS concentration. Plant aging was also accelerated, and the dry weight of plants increased when treated with 5 µg/mL LPS. Moreover, the impact of exogenous LPS treatment on the protein, starch, and lipid content in grains was relatively negligible. Our results showed that A. brasilense LPS affected some aspects of wheat development such as plant aging and spike formation, but not grain chemical composition or grain yield.

A case report of proliferative glomerulonephritis with monoclonal immunoglobulin M-kappa deposits without associated lymphoproliferative disorder or detectable paraproteinemia.

A 53-year-old man presented with proteinuria and hematuria. No significant abnormality was detected in his physical examination or laboratory tests, including evidence of paraprotein in serum and urine. Renal biopsy revealed mesangial proliferation, thickened glomerular basement membranes, and spike formation. Immunofluorescence revealed deposition of immunoglobulin (Ig) M heavy chain, kappa (κ) light chain, and complement component C3 along capillary walls in the glomeruli. Light chain staining indicated significant restriction, because only κ chain, not lambda chain, was present in glomeruli. Aggregated electron dense deposits were observed in the subepithelial area and within the lamina densa on electron-microscopic examination. Cryoglobulinemia and amyloidosis were ruled out. Clinically, steroid therapy was not initiated due to patient preference, and the only prescribed medication was an angiotensin II receptor blocker. At the approximately 3-year follow-up, estimated glomerular filtration rate had decreased very mildly. The present case demonstrates that deposition of monoclonal IgM-κ may be associated with membranoproliferative glomerulonephritis-like changes in the glomeruli. Although no underlying hematological abnormality or paraproteinemia was observed in this case within the range of limited clinical examination, the patient's condition is consistent with proliferative glomerulonephritis with monoclonal IgM deposits, similar to the recently established proliferative glomerulonephritis with monoclonal IgG deposits. Further elucidation of the pathophysiology and effective treatments of the disorder should be expected in the future through the accumulation of similar cases.

Nanostructuring and wettability of ion treated Au thin films

The formation of Au nanostructures (NSs) under 8 keV Ne+ ion treatment of Au thin film is investigated to explore the involved mechanism using experimental and theoretical approaches. This study is based on atomic force microscopy, Rutherford backscattering spectrometry, and contact angle measurements. The results are discussed in the light of the thermal spike model and tridyn simulation. It is observed in the simulations that Ne ion treatment results in ejection of atoms from the surface due to elastic collision induced transfer of energy and increase in lattice temperature due to the formation of thermal spikes. The effect of ion dose on the surface morphology is also explored using a two-dimensional detrended fluctuation analysis (DFA).The DFA gives information about the fractal dimension (Df) and Hurst exponent (H) of the surface. The fractal dimension (Df) shows that irregularity of a surface is significantly influenced by ion treatment. The contact angle of the water droplet with the surface is discussed with the interface width and fractal dimension. The competition among nuclear sputtering, de-wetting, and diffusion processes results in the formation of NSs. It also demonstrates that the experimental findings are in good agreement with the theoretical results.

On electron attachment effect on characteristics of the DBD in chlorine and its mixtures with xenon

The electron attachment effect on DBD characteristics in chlorine and its mixtures with xenon has been studied. Characteristics of the DBDs in pure chlorine and in xenon-chlorine mixtures with a chlorine fraction of 0.1-5% were modeled using the fluid model. It is shown that the electron attachment limits a magnitude of the DBD current, contributes to formation of multiple current spikes, appearance of a double layer near the dielectric surface and formation of XeCl* excimer molecules, and leads to a redistribution of the power deposited into the discharge: more power is deposited into ions and less power is deposited into electrons.

窒素の穂肥・開花期追肥によるもち性大麦の高β‐グルカン含量化

窒素の穂肥・開花期追肥によるもち性大麦の高β‐グルカン含量化

Formation of Ag-Al Alloy in context of PERC solar cell metallization

The Ag-Al spike formation at the transition between silver pad and aluminum metallization of the rear side of industrial PERC solar cells was investigated. Silver and aluminum layers were deposited by thermal evaporation on top of silicon nitride layers forming a system of reduced complexity. The absence of glass frit and other usual components of metallization paste leads to a focused study on interaction between the metal alloy and passivation layer. The samples were tempered stepwise from 400°C to 1000°C using a rapid thermal processing tool. X-ray diffraction measurement reveals the expected formation of Ag2Al phase, starting at 400°C. Furthermore, silicon was detected which is accompanied with the occurrence of square shaped indentations in the metal layer, which are the base area of pyramidal metal spikes penetrating the silicon. The formation of these spikes occur for anneal temperatures above 700°C, whereas the silicon nitride shows a high resistance against the molten alloy. The silicon nitride has to contain pinholes to enable a contact between metal and silicon substrate to form these spikes. Electrical characterization of these unintended contacts show an ohmic behavior, similar to the Al-Si system. In combination with the previous observations, a model for the spike formation at the rear side of industrial solar cells is presented.

Molecular mapping and genetic analysis of a QTL controlling spike formation rate and tiller number in wheat

Spike formation rate (SR), which is based on maximum tiller number per unit area and spike number per unit area, is an important yield-related trait in wheat. Increasing the spike formation rate reduces growth competition and wastage of photosynthate from ineffective tillers. Unfortunately, research studies involving quantitative trait locus (QTL) mapping for wheat spike formation rate are limited. In the present study, a set of 371 recombinant inbreed line (RIL) population, which were derived from 1BL/LRS wheat-rye translocation lines CN18 and T1208, was analysed by simple sequence repeat (SSR) markers. Genetic analysis showed that a stable and major QTL (QSR.sicau-4D) for spike formation rate was localized to chromosome 4D and explained 18.24% and 24.48% of the observed phenotypic variance in 2015 and 2016, respectively. This QTL was closely linked to SSR marker Xcfd23, and the genetic distance between the flank markers was 3.28cM. Furthermore, QSR.sicau-4D might be a novel pleiotropic QTL, which also controlled maximum tiller number per unit area (QMTN.sicau-4D) and tiller number during pre-winter per unit area (QTNW.sicau-4D). The marker Xcfd23 associated with SR may be utilized in marker-assisted selection in wheat breeding.

Generation of Rogue Waves in Gyrotrons Operating in the Regime of Developed Turbulence.

Within the framework of the average approach and direct 3D PIC (particle-in-cell) simulations, we demonstrate that the gyrotrons operating in the regime of developed turbulence can sporadically emit "giant" spikes with intensities a factor of 100-150 greater than the average radiation power and a factor of 6-9 exceeding the power of the driving electron beams. Together with the statistical features such as a long-tail probability distribution, this allows the interpretation of generated spikes as microwave rogue waves. The mechanism of spikes formation is related to the simultaneous cyclotron interaction of a gyrating electron beam with forward and backward waves near the waveguide cutoff frequency as well as with the longitudinal deceleration of electrons.

High-contrast sub-Doppler absorption spikes in a hot atomic vapor cell exposed to a dual-frequency laser field

The saturated absorption technique is an elegant method widely used in atomic and molecular physics for high-resolution spectroscopy, laser frequency standards and metrology purposes. We have recently discovered that a saturated absorption scheme with a dual-frequency laser can lead to a significant sign reversal of the usual Doppler-free dip, yielding a deep enhanced-absorption spike. In this paper, we report detailed experimental investigations of this phenomenon, together with a full in-depth theoretical description. It is shown that several physical effects can support or oppose the formation of the high-contrast central spike in the absorption profile. The physical conditions for which all these effects act constructively and result in very bright Doppler-free resonances are revealed. Apart from their theoretical interest, results obtained in this manuscript are of great interest for laser spectroscopy and laser frequency stabilization purposes, with applications in laser cooling, matter-wave sensors, atomic clocks or quantum optics.

Role of graphene layers on the radiation resistance of copper–graphene nanocomposite: Inhibiting the expansion of thermal spike

Metal–graphene nanocomposites are expected to have excellent radiation resistance. The intrinsic role of the graphene layers (GrLs) in their performance has not been fully understood. Five copper–graphene nanocomposite (CGNC) systems were used to investigate the detailed mechanisms underpinning this behaviour by atomistic simulation. Results showed that GrLs can reduce the formation, growth, and intensity of the thermal spike of CGNC; this effect became more evident with the increasing number of layers of graphene. The role of the GrLs can be explained by three mechanisms: first, the ultra-strength C–C bonds of graphene hindered the penetration of high-energy atoms, second, the number of recoiled atoms decreased with the increasing number of layers of graphene, and third, the energy dissipation along the graphene planes also indirectly weakened the damage caused to the entire system. These mechanisms may provide a pathway to prevent material degradation in extreme radiation environments.

Controlled Growth of Gold Nanostars: Effect of Spike Length on SERS Signal Enhancement.

Two different types of gold nanostars (Au NS), namely, short-spiked nanostars (SSNS) and long-spiked nanostars (LSNS), are prepared by using a hexagonal lyotropic liquid-crystalline (LLC) phase as a template. The formation, size and length of spikes or arms of the resultant Au NS are controlled by preparation in either a hexagonal LLC phase or an isotropic phase. These NS are anchored onto indium tin oxide (ITO) electrodes through a self-assembled monolayer of 3-mercaptopropyltrimethoxysilane, which acts as a linker molecule. Structural and morphological characterisations of SSNS- and LSNS-anchored ITO electrodes are performed by means of microscopic and spectroscopic analyses. Further electrochemical techniques, namely, cyclic voltammetry and electrochemical impedance spectroscopy, are also used to confirm the immobilisation of these Au NS on ITO electrodes and to study the electrochemical characteristics. These studies clearly reveal the formation of star-shaped, branched, anisotropic nanostructures of gold during the template preparation method and these Au NS are successfully anchored onto ITO electrodes through a covalent immobilisation strategy. Furthermore, the SERS activity of these Au NS is analysed by using glutathione and crystal violet as analytes and by employing glass and ITO as substrates. It is interesting to note that SSNS show a significant enhancement in SERS signals relative to those of LSNS.

Current-horn suppression for reduced coherent-synchrotron-radiation-induced emittance growth in strong bunch compression

Control of coherent synchrotron radiation (CSR)-induced emittance growth is essential in linear accelerators designed to deliver very high brightness electron beams. Extreme current values at the head and tail of the electron bunch, resulting from strong bunch compression, are responsible for large CSR production leading to significant transverse projected emittance growth. The Linac Coherent Light Source (LCLS) truncates the head and tail current spikes which greatly improves free electron laser (FEL) performance. Here we consider the underlying dynamics that lead to formation of current spikes (also referred to as current horns), which has been identified as caustics forming in electron trajectories. We present a method to analytically determine conditions required to avoid the caustic formation and therefore prevent the current spikes from forming. These required conditions can be easily met, without increasing the transverse slice emittance, through inclusion of an octupole magnet in the middle of a bunch compressor.

山口県の中山間地における播種期の違いがコムギ・裸麦4品種の 収量および幼穂形成に及ぼす影響

山口県の中山間地における播種期の違いがコムギ・裸麦4品種の 収量および幼穂形成に及ぼす影響

How Actin Cytoskeleton Dynamics Induce Membrane Tubulations

E-mail: cecile.sykes@curie.frWeb: http://umr168.curie.fr/en/Sykes-groupCell deformations are part of many vital processes such as division, motility orintracellular transport. They result from the continuous re-organization of the actin cytoskeleton underneath the membrane. In order to unveil how biochemical assembly can change membrane shape, we develop a minimal system based on purified components to control all the relevant parameters.We reconstruct a finely tuned actin network on cell-sized liposomes to address the respective role of membrane and actin network in membrane tubulation. The actin network is reconstituted at the outer surface of fluorescently labeled liposomes with purified proteins that allow to follow simultaneously membrane and actin dynamics. The system is tuned to generate a branched cortical network next to the membrane. We demonstrate that the actin cytoskeleton induces the formation of membrane tubes with different morphologies that are reminiscent of endocytosis and finger-like protrusions in cells: tubes are spontaneously pulled outside the liposomes and spikes grow towards liposome centers. By decreasing membrane tension via osmotic shock, we show that spike formation is promoted without affecting tubes pulling. These results suggest that these structures are two independent deformations relying on different mechanisms, both based on membrane deformation induced by cytoskeletal dynamics. This investigation highlights how membrane tubulation depends on a mechanical balance between the membrane and the actin network.

Transition from a beads-on-string to a spike structure in an electrified viscoelastic jet

A one-dimensional numerical simulation is performed to study the nonlinear behaviors of a perfectly conducting, slightly viscoelastic liquid jet under a large radial electric field. A singular spike structure different from a beads-on-string structure is detected. The electric field is found to be the key factor for the formation of spikes. The transition from a beads-on-string to a spike structure occurs at sufficiently large electric fields. Moreover, the transition occurs more easily for smaller wave numbers. Viscosity is found to suppress spikes while elasticity promotes them. The mechanism responsible for spike formation is further explored by examining the maximum radius of the jet in the beads-on-string case. The capillary and electrostatic forces prove to be dominant in droplets, and the transition takes place when the electrostatic force exceeds the capillary force. The self-similarity in spikes is discussed. Different from the transition moment, the inertial, electrostatic, and solvent viscous forces are important in a developed spike.

The influence of magnetic field on the physical explosion of a heavy gas cloud

ABSTRACTRichtmyer–Meshkov (RM) instability arises during the eruption of heavy gas cloud. In this study, we numerically study the effects of magnetic fields on the RM instability induced by the ionised cylindrical and spherical heavy gas cloud eruption using corner transport upwind + constrained transport algorithm. Our numerical results show that magnetic fields can suppress the formation of spike and bubble structures induced by the eruption in both cylindrical and spherical cases. The magnetic pressure of the interface along the perpendicular direction of magnetic field is the main factor to control the distortion of the interface. Even weak magnetic fields can drastically alter the evolution of the cloud and result in different distributions and amplifications of the magnetic pressure, which will affect further transformation of RM instability during the ionised gas eruption. Meanwhile, the magnetic pressure on the interface decreases gradually when the initial magnetic field is relatively large; when the initial magnetic field is small enough, the opposite results will occur.

Interaction of genes determining the spike shape of wheat and those located in the 5AL chromosome

The spike parameters of hexaploid wheats from the genus Triticum L. are determined by the major genes and play an important role in systematics. Having a strong pleiotropic effect, they also have practical importance. In this work, the interaction of the dominant genes QS and Q with the dominant gene C17648 determining the shape of the spike was investigated. The gene Q is located in the 5AL chromosome and determines the formation of the elongated lax spike in the T. spelta L. species. The homoeoallelic gene QS introgressed into bread wheat from Aegilops speltoides Tausch. and causing the formation of the speltoid spike is also located in the 5AL chromosome of the 84/98w line. The C17648 gene is analogous in the phenotypic manifestation to the C gene determining the formation of a dense short spike on a short culm as in T. compactum Host. It was mapped to the 5AL chromosome in the bread wheat line ANBW-5A and the donor of the gene was a mutant of durum wheat. In the present work, the spike length, spikelet number, index of spike density, and stem length were studied in F1, F2, and F3 of three different hybrid populations. It was shown for the first time that the C17648 gene is epistatic to the dominant genes QS and Q. It was manifested in the formation of compact spikes in F1 hybrids and in the numerical predominance of plants with a compact spike in F2. At the same time, the gene C17648 showed a smaller effect on stem length and did not affect the number of spikelets. Using the genetic analysis, it was found that genes QS and Q are independently inherited from gene C17648, although a strong link was observed between the QS or Q and b1 gene.

Weakly nonlinear instabilities of a liquid ring

The weakly nonlinear instability of a liquid ring is investigated by perturbation method and illustrates several important features at the early stage of evolution after destabilization. When the centerline maintains circular, the ring would transform into a droplet chain during its shrinkage, but tends to possess some local pinching during the expansion. If there is an additional distortion of the centerline, an evident tendency to protrude spikes, on each of which a droplet may be formed, is predicted. The analysis concentrates on inviscid cases, because the viscosity of ring liquid is proven to merely affect the base state. Besides, the interaction between instability modes is studied to understand the irregularity of perturbed surface and centerline, and the four locations where the irregularity appears to the maximum extent are discovered. All these results are confirmed by numerical simulations of the same model and experimental observations on ring-shaped the rim of drop-splash ejecta, and hence are related intrinsically with the spike formation process.