Weak Maxima Research Articles

Methodological approaches to hygienic assessment of safe distances when performing agricultural work using unmanned aircraft systems

Introduction. Methods and technologies for assessing and managing risk are becoming the basic mechanisms for ensuring the protection of the health in citizens and the environment from the harmful effects of environmental factors. This is explained by the presence of constant threats associated with the influence of these factors, including the use of modern methods of introducing chemicals during agricultural work. Agricultural unmanned aircraft systems (AUAS) designed to spray pesticides are increasingly being used around the world. The basis for the safe use of pesticides for the population is to minimize the possibility of their spread through the air and settling on the soil outside the treated area, which is ensured by compliance with hygienic requirements for equipment used in agriculture, application regulations, weather conditions during processing, and the size of the sanitary gap between the treated area and settlements, water bodies, etc. The purpose of this study was to substantiate the safe distances from areas of agricultural application of pesticides using AUAS to objects regulated in accordance with sanitary legislation (settlements, sources of household, drinking and cultural water use, etc.). Materials and methods. The demolition formed during the application of pesticides of various purposes using AUAS has been studied. The content of drugs carried away by air currents was monitored by measuring the concentration of the substance in the atmospheric air and deposited on the “blue ribbon” filters placed in Petri dishes outside the processing band. Results. The maximum concentrations of substances in the atmospheric air at all distances from the treatment site were below their hygienic standards for atmospheric air. There is a clear decrease in concentrations in air samples as they move away from the treated area and a nonlinear decrease in concentrations in sedimentation samples with the presence of weak local maxima. Limitations. A small sample of the studied substances, due to the limited time of the study, does not allow unambiguously identifying the patterns of drift formation depending on their physical-chemical properties, in particular volatility, molecular weight, etc. Conclusion. The data obtained indicate to the need to continue research for a reasoned correction or confirmation, proposed based on the results of the tests, of the safe distance (700 m) from the sites treated with pesticides to the facilities normalized in accordance with sanitary legislation.

A fluorescent "Turn-ON" probe with rapid and differential response to HSA and BSA: quantitative detection of HSA in urine.

The present study provides insight into the differential response of a benzimidazole-malononitrile fluorescent "Turn-ON" probe on interaction with two structurally similar proteins, BSA and HSA. Compound 6 shows more sensitivity towards the two SAs, which is completely lost in the case of compound 7, synthesized by substitution on 6. The aggregates of compound 6 show absorption maxima at 385 nm and weak emission maxima at 565 nm. Compound 6 forms a new emission band at 475 nm on gradual addition of BSA (200 μM) along with a slight increase in the emission band at 565 nm. However, on addition of HSA (50 μM), a new band at 475 nm is formed. In contrast to BSA, in the case of HSA, 50% quenching is observed in the emission band of compound 6 at 565 nm. The new band formed on the interaction of 6 with BSA shows four-fold more enhancement compared to HSA. Furthermore, the mechanism of interaction of 6 with serum albumin has been investigated through lifetime-fluorescence analysis, site-selective drug experiments, dynamic light scattering, FE-SEM, FT-IR, etc. Molecular docking studies and site marker drug displacement experiments reveal differential interactions of 6 towards the two structurally similar proteins. Aggregates of 6 with an average hydrodynamic size of 100-190 nm are disassembled on adding BSA and HSA, and the size of the serum albumin and 6 complex decreases to 10-20 nm, revealing the ligand's encapsulation in the serum albumin cavity. Practical applicability for the quantitative detection of HSA in human urine samples is also demonstrated. The high binding affinity, sensitivity, selectivity and differential response of probe 6 towards two serum albumins (HSA and BSA) and significant quantification of HSA in urine samples shows the potential ability of this probe in medical applications.

Critical current of a layered high-temperature superconductor with artificial pinning centers: the Monte Carlo simulation

Current–voltage characteristics (EJ curves) and magnetic field dependences of the critical current have been calculated for a superconductor with artificial pinning in the form of submicron-sized holes and tilted radiation defects. Calculations have been performed within the framework of the three-dimensional model of a layered HTS by means of the Monte Carlo method. S-shaped features of the EJ curves have been observed for a sample with a rectangular lattice of holes. Such features have not occurred in calculations for HTSs with non-magnetic pinning centers before, but they have been observed in experimental studies. In this paper, the features occurred in magnetic fields close to 290 Gs (which is the lower critical field for the Bi2Sr2CaCu2O8-δ superconductor at 1 K) and they were sensitive to the magnitude of the external magnetic field. In addition, the features were more prominent at temperatures below 30 K and in samples with weak intrinsic pinning, and they were connected with matching-like effects in the vortex system (i. e. a certain number of vortices being pinned on each hole, screening new vortices from entering the sample). For samples with tilted radiation defects, decreasing field dependences of the critical current have been obtained, showing weak maxima near the lower critical field of the superconductor. Calculations have shown that, at a fixed value of the external field, the critical current decreases with the increasing tilt angle of the defects.

Interaction of end-gas autoignition and cold wall in closed chamber

The presence of cold walls in spark-ignition (SI) engines could induce the interaction with end-gas autoignition. This interaction is numerically studied in the current work considering detailed chemistry and transport, with emphasis on near-wall flame structures and dynamics, as well as autoignition-affected wall heat flux. Two alternative fuels, hydrogen, and dimethyl ether (DME), are considered. In hydrogen/air mixtures, autoignition first develops in the end-gas and leaves an unburnt near-wall region. The combustion mode in this region then sequentially behaves as spontaneous ignition, laminar flame, and low-to-intermediate temperature reaction. Correspondingly, the contribution of diffusion and convection in the energy budget respectively increases and decreases as the reaction front moves towards the wall. End-gas autoignition also introduces strong pressure waves propagating back-and-forth, which subsequently lead to multiple local maxima on the temporal evolution of wall heat flux. Consequently, the maximum wall heat flux no longer changes monotonically with both the wall temperature and the quenching distance. Furthermore, the role of low-temperature chemistry (LTC) is studied using DME/air mixtures, which exhibits typical multi-stage heat release and Negative Temperature Coefficient (NTC) behaviors. It is also noted that, the influence of pressure wave is minimal when the unburnt mixtures have relatively low energy density, such as at off-stoichiometric conditions and/or lower initial pressures. Specifically: consistent to distinct three-stage homogeneous ignition at certain fuel-lean conditions (ϕ = 0.25) and intermediate initial temperature (typically around T0 = 600–750 K), in the corresponding 1D case three-stage end-gas autoignition respectively evolves into the near-wall cool, warm and hot flame; in the case at relatively low initial pressures, only the first-stage autoignition occurs in the end-gas, and as such LTC slightly increases the wall heat flux and advances flame quenching. As the reactivity of unburnt mixtures becomes higher, LTC and HTC respectively introduce strong and weak knocking combustion. Multiple weak and strong local maxima are observed in the temporal evolution of wall heat flux, both of which changes non-monotonically with the wall temperature.

Transformation microstructures in pyrolite under stress: Implications for anisotropy in subducting slabs below the 660 km discontinuity

The ‘660’ discontinuity is often associated with a phase transitions in pyrolite at about 24 GPa. There are ubiquitous reports of seismic anisotropy below the ‘660’ which are difficult to explain from a mineralogical point of view. In this study, we implement multigrain crystallography X-ray diffraction in the laser-heated diamond anvil cell in order to track microstructures induced by phase transitions at the pressure and temperature conditions of the discontinuity. Before the onset of transformation, garnet is isotropic with ringwoodite displaying a weak 001 texture. After the transformation, bridgmanite displays strong 001 transformation textures which we attribute to growth under stress. Davemaoite exhibits weak maxima in 101 and 111 orientations with ferropericlase displaying no texture. The results are used to model anisotropy in a subducting slab, with a prediction of no anisotropy above the ‘660’ and up to 1.28% (0.08 km/s) shear wave splitting below the ‘660’. In addition, we predict VSV>VSH for horizontally traveling waves and near-vertical subduction and VSV<VSH in the case a slab impinging below the boundary layer.

Thermal stability of rhombohedral α- and monoclinic β-Ga2O3 grown on sapphire by liquid-injection MOCVD

We investigate the thermal stability of single-phase undoped epitaxial rhombohedral α- and bi-axially-symmetric, monoclinic β-Ga2O3 thin films grown on sapphire substrates by liquid-injection metalorganic chemical vapor deposition (LI-MOCVD) by means of in-situ high-temperature X-ray diffraction (HT-XRD) and room temperature (RT) cathodoluminescence (CL). Ga2O3 layers were vacuum annealed up to 1100 °C, while monitoring the respective 303‾0 and 6‾03 reflections of α- and β-phase Ga2O3. α-Ga2O3 layers were found to withstand the vacuum annealing at 700 °C/20 min, 750 °C/10 min, and 800 °C/8 min without notable degradation, however an indication of reversible biaxial in-plane compressive strain was observed for annealing temperatures close to 800 °C. Annealing at temperatures above 825 °C led to complete layer degradation and partial phase transformation to (010) β-Ga2O3. β-Ga2O3 layers showed no notable degradation or structural changes after the annealing at 1100 °C/30 min, however an indication of reversible biaxial in-plane tensile strain was observed for prolonged annealing at 1100 °C. RT CL spectra revealed the Ga2O3 emission consisted of several distinctive luminescence bands (red, green, blue, and two UV bands). Relatively weak but distinctive signal maxima with energy close to the expected bandgap energies of α- and β-Ga2O3, at 5.3 and 5.0 eV, respectively, were observed and attributed to their near band-edge (NBE) emissions.

Towards Efficient Blue Delayed-Fluorescence Molecules by Modulating Torsion Angle Between Electron Donor and Acceptor

Towards Efficient Blue Delayed-Fluorescence Molecules by Modulating Torsion Angle Between Electron Donor and Acceptor

Diurnal Cycle of Precipitation Features Observed during DYNAMO

AbstractThis study uses shipborne (R/V Roger Revelle and R/V Mirai) radar, upper-air, ocean, and surface meteorology datasets from the DYNAMO field campaign to investigate the diurnal cycle (DC) of precipitation over the central Indian Ocean related to two distinct Madden–Julian oscillations (MJOs) observed. This study extends earlier studies on the MJO DC by examining the relationship between the DC of convective organization and the local environment and comparing these results on- and off-equator. During the suppressed phase on-equator, the DC of rain rates exhibited two weak maxima at 1500 and 0100 LT, which was largely controlled by the presence of sub-MCS nonlinear precipitation features (PFs). During the active phase on-equator, MCS nonlinear features dominated the rain volume, and the greatest increase in rain rates occurred between 2100 and 0100 LT. This maximum coincided with the maxima in convective available potential energy (CAPE) and sensible heat flux, and the column moistened significantly overnight. Off-equator, the environment was much drier and there was little large-scale upward motion as a result of limited deep convection. The DC of rain rates during the active phase off-equator was most similar to the DC observed during the suppressed phase on-equator, while rainfall off-equator during the suppressed phase did not vary much throughout the day. The DC of MCS nonlinear PFs closely resembled the DC of rainfall during both phases off-equator, and the DC of environmental parameters, including sea surface temperature, CAPE, and latent heat flux, was typically much weaker off-equator compared to on-equator.

Diagnosing the Influence of a Receding Snow Boundary on Simulated Midlatitude Cyclones Using Piecewise Potential Vorticity Inversion

AbstractPrevious research has found a relationship between the equatorward extent of snow cover and low-level baroclinicity, suggesting a link between the development and trajectory of midlatitude cyclones and the extent of preexisting snow cover. Midlatitude cyclones are more frequent 50–350 km south of the snow boundary, coincident with weak maxima in the environmental Eady growth rate. The snow line is projected to recede poleward with increasing greenhouse gas emissions, possibly affecting the development and track of midlatitude cyclones during Northern Hemisphere winter. Detailed examination of the physical implications of a modified snow boundary on the life cycle of individual storms has, to date, not been undertaken. This study investigates the impact of a receding snow boundary on two cyclogenesis events using Weather Research and Forecasting Model simulations initialized with observed and projected future changes to snow extent as a surface boundary condition. Potential vorticity diagnosis of the modified cyclone simulations isolates how changes in surface temperature, static stability, and relative vorticity arising from the altered boundary affect the developing cyclone. We find that the surface warm anomaly associated with snow removal lowered heights near the center of the two cyclones investigated, strengthening their cyclonic circulation. However, the direct effect of snow removal is mitigated by the stability response and an indirect relative vorticity response to snow removal. Because of these opposing effects, it is suggested that the immediate effect of receding snow cover on midlatitude cyclones is likely minimal and depends on the stage of the cyclone life cycle.

SOLVING MINERALOGY PROBLEMS WITH THE HELP OF THE “ORIGIN" PACKAGE

Algorithms for solving typical mineralogical problems associated with quantitative x-ray spectral analysis and quantitative x-ray phase analysis using the program “Origin” are developed. The calculation of the areas and midpoint of spectral lines using the tabular processor of the program “Origin” is considered. Various approaches to determining the parameters of spectral lines using the least squares method using the standard functions of the program “Origin” were tested. The creation of a user function for approximation of diffraction maxima by the Cauchy function taking into account the doublet character of Ka series of x-rays is also considered. Various built-in algorithms for smoothing functions (based on averaging, polynomial approximation and Fourier analysis – synthesis) were tested to find weak diffraction maxima against strong noise; optimal schemes for the application of these algorithms were found. The considered algorithms can be applied in universities when processing the results of laboratory works on the topics "Analysis of spectra of emission of atoms", "Quantitative x-ray spectral analysis" and "Quantitative x-ray phase analysis".

Lattice-preferred orientation development in experimental and natural fine-grained dolomite shear zones

We compare microstructures and lattice preferred orientations (LPO) in shear zones formed in two experimentally deformed and two naturally deformed dolomites. Experimental samples were deformed at 900 °C and laboratory strain rates, and naturally deformed dolomites were collected from the Pioneer Landing thrust and Town Knobs thrust of the Southern Appalachians, deformed at ~300 °C and ~240 °C, respectively, at tectonic strain rates. Coarse-grained host dolomite, in all samples, exhibits undulatory extinction, subgrains, recrystallized grains, and, in the naturally deformed dolomites, fractures. Two types of fine-grained shear zones are characterized in experimentally deformed dolomites: 1) a fine-grained zone of recrystallized dolomite generated during axial shortening of coarse-grained dolomite that initially deformed by dislocation creep, with strain localization initiated by grain-size sensitive deformation processes and 2) a synthetic, fine-grained dolomite layer placed between coarse-grained dolomite shear pistons. Microstructures and lattice preferred orientations of the experimentally sheared dolomite reflect the concomitant operation of dislocation creep, diffusion creep, and grain boundary sliding. Microstructures, including subgrains, recrystallized grains, and four-grain junctions, and lattice preferred orientations that consist of weak c-axis maxima in the natural shear zones are similar to the experimental shear zones, however, a slightly stronger LPO, more common subgrains and the lack of four-grain junctions indicate that dislocation creep dominates within dolomites deformed at lower temperatures (240 °C).

Impact of Mountainous Topography on Surface-Layer Parameters During Weak Mean-Flow Conditions

We investigate surface-layer characteristics over a mountainous ridge in the Central Himalayas, utilizing tower-based fast-response micrometeorological observations (at 12 and 27 m above ground level) for the winter months November 2013–January 2014. During this period, the site generally experienced clear skies and weak synoptic flow (wind speed < 2 m s−1), favouring a strong diurnal evolution of the atmospheric boundary layer. The observations show a regular change in wind direction from north-easterly during the night-time to westerly during the daytime throughout the season, indicating the systematic development of a mountain circulation due to changes in heating of the mountain slopes as the day advances. Considering the variations in wind direction and topography of the site, the tilt corrections are implemented sector-wise by segregating the data into three sectors, thus estimating three sets of coefficients for the tilt correction. Observations during fair-weather conditions (59 days only) are analyzed with the sensible heat flux (H) showing large diurnal variations, which are in-phase with the mean vertical velocity. The afternoon peak value of H is found to be ≈ 116 ± 80 W m−2. In contrast, diurnal variations of momentum flux and turbulent kinetic energy are less prominent with rather weak maxima occurring between 0900 and 1300 IST, the period when wind direction changes over the ridge. Variations of the dimensionless standard deviations of the vertical velocity component and temperature are found to scale with the stability parameter z/L under convective conditions, while taking into account the effect of self-correlation. The constancy of fluxes with height, slope-flow buoyancy and stress divergence are also analyzed to provide a rigorous evaluation of Monin–Obukhov similarity theory based on two-level turbulence measurements.

Complex strain induced structural changes observed in fibrin assembled in human plasma.

The structure of the core scaffold of blood clots, the interlinked 3-dimensional network of fibrin fibers, is modified by mechanical forces generated by platelet driven clot retraction, wound repair and shear stress through blood flow. Here X-ray diffraction is used to investigate how uniaxial strain, ε (ε = extension/original length), alters fiber structure in highly aligned human plasma clots covalently cross-linked by Factor XIIIa. Three stretch sensitive axially repeating structures are identified. Firstly, the foundation structure with an initial ≈22 nm axial repeat stretches, fades then disappears at ε ≈ 0.40. A second, lengthened transitory structure emerges at the low strains (ε ≈ 0.20) believed to be developed by cells. Finally, a third shortened structure appears after relaxation. Simultaneously as strain progresses an increasing fraction of molecules become axially disordered. Weak off-axis diffraction maxima indicate the presence of lateral ordering up to ε = 0.40 that partially recovers after relaxation. The reappearance of both axial and lateral order on relaxation demonstrates a surprising resilience in structure. In view of the range and importance of fibrin's functions, this structural heterogeneity, triggered in vivo by cell traction or shear stress, is likely to be of clinical significance.

Lattice dynamics in monolayer and few-layer SnSe2

Hexagonal tin diselenide $(6\mathrm{Hb}\ensuremath{-}{\mathrm{SnSe}}_{2})$, a two-dimensional (2D) layered metal dichalcogenide from the IVA and VIA groups, has recently drawn numerous attention in 2D nano-optoelectronics. In this paper, we investigate characteristic lattice dynamics of mechanically exfoliated mono- and few-layer $6\mathrm{Hb}\ensuremath{-}{\mathrm{SnSe}}_{2}$ samples by Raman spectroscopy. Bulk ${\mathrm{SnSe}}_{2}$ has all four Raman active modes of low-frequency shear ${E}_{g}^{2}$ and layer-breathing ${A}_{1g}^{2}$ modes, and high-frequency intralayer vibrational ${E}_{g}^{1}$ and ${A}_{1g}^{1}$ modes observed around 18.9, 33.6, 107.9, and $182.1\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}1}$, respectively. From polarized Raman measurements, we find that ${E}_{g}^{1}$ mode intensity is independent of polarization configuration and increases linearly with layer number, which provides an effective approach to determine sample thickness. From low-temperature Raman measurements, ${E}_{g}^{1}$ and ${A}_{1g}^{1}$ mode temperature coefficients of one-layer, three-layer, and bulk ${\mathrm{SnSe}}_{2}$ are around $\ensuremath{-}0.018$ and $\ensuremath{-}0.014\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}1}/\mathrm{K}$, whereas they have almost zero values for low-frequency ${E}_{g}^{2}$ and ${A}_{1g}^{2}$ modes of bulk ${\mathrm{SnSe}}_{2}$ due to different thermal responses of intralayer and interlayer vibrations. Using multiple excitation laser lines of 488, 514.5, 568, 647, and 785 nm, ${E}_{g}^{1}$ and ${A}_{1g}^{1}$ mode intensities of bulk ${\mathrm{SnSe}}_{2}$ have a similar trend with weak maxima around 2.41 eV. Our work provides valuable information about ${\mathrm{SnSe}}_{2}$ lattice vibrations for further fundamental research and potential applications in 2D devices such as thermoelectric and infrared light detectors.

A Unified Theory for the Great Plains Nocturnal Low-Level Jet

Abstract A theory is presented for the Great Plains low-level jet in which the jet emerges in the sloping atmospheric boundary layer as the nocturnal phase of an oscillation arising from diurnal variations in turbulent diffusivity (Blackadar mechanism) and surface buoyancy (Holton mechanism). The governing equations are the equations of motion, mass conservation, and thermal energy for a stably stratified fluid in the Boussinesq approximation. Attention is restricted to remote (far above slope) geostrophic winds that blow along the terrain isoheights (southerly for the Great Plains). Diurnally periodic solutions are obtained analytically with diffusivities that vary as piecewise constant functions of time and slope buoyancies that vary as piecewise linear functions of time. The solution is controlled by 11 parameters: slope angle, Coriolis parameter, free-atmosphere Brunt–Väisälä frequency, free-atmosphere geostrophic wind, radiative damping parameter, day and night diffusivities, maximum and minimum surface buoyancies, and times of maximum surface buoyancy and sunset. The Holton mechanism, by itself, results in relatively weak wind maxima but produces strong jets when paired with the Blackadar mechanism. Jets with both Blackadar and Holton mechanisms operating are shown to be broadly consistent with observations and climatological analyses. Jets strengthen with increasing geostrophic wind, maximum surface buoyancy, and day-to-night ratio of the diffusivities and weaken with increasing Brunt–Väisälä frequency and magnitude of minimum slope buoyancy (greater nighttime cooling). Peak winds are maximized for slope angles characteristic of the Great Plains.

Platinum(II)‐Mediated Double Coupling of 2,3‐Diphenylmaleimidine with Nitrile Functionalities To Give Annulated Pentaazanonatetraenate (PANT) Systems

Treatment of trans-[PtCl2(NCR)2] [R = Et 1, nPr 2, tBu 3, CH2Ph 4, Ph 5, p-CF3C6H4 6, NMe2 7, NEt2 8, N(CH2)5 9] with 2.5 equiv. of 2,3-diphenylmaleimidine in CH2Cl2 at room temperature for 5 min [for R = p-CF3C6H4 6, NMe2 7, NEt2 8, N(CH2)5 9] or 14 h (for R = Et 1, nPr 2, tBu 3, CH2Ph 4, Ph 5) furnishes (1,3,5,7,9-pentaazanona-1,3,6,8-tetraenato)platinum(II) [(PANT)PtII; PtCl{HN=C(R)N=CN[C(Ph)=C(Ph)]C=NC(R)=NH}] complexes 10–18. These species are formed by platinum(II)-mediated double coupling of 2,3-diphenylmaleimidine with both nitrile ligands. The formulation of the complexes was supported by satisfactory C, H, and N elemental analyses, which were in agreement with HRESI-MS, IR, and 1H and 13C{1H} NMR spectra. The structures of 10, 11·1/8nC6H14, 15, 16·CCl4, and 17·CHCl3 were determined by single-crystal X-ray diffraction. Absorption and emission studies were performed on representative complexes 10, 15, and 18, and the results show weak phosphorescence maxima at around 730–750 and 770–820 nm in CH2Cl2 and in the solid state, respectively. Further insight into the photophysical properties was gained by time-dependent density functional theory (TD–DFT) with detailed analysis of the corresponding frontier molecular orbitals for the lower-lying transition. The calculated energies of the T1 state (in terms of wavelength) are 715.8 nm for 10, 764.6 nm for 15, and 697.7 nm for 18, and these values are in good agreement with the trend of the first vibronic peaks of their phosphorescence spectra.

Magnetocaloric properties of manganese(III) porphyrins bearing 2,6-di-tert-butylphenol groups

Magnetocaloric effect (MCE) and heat capacity during the magnetization of (5,10,15,20-tetrakis(3,5-di-tert-butyl-4-hydroxyphenyl)porphynato) manganese (III) chloride (1), (5-(4-hydroxyphenyl)-10,15,20-tris(3,5-di-tert-butyl-4-hydroxyphenyl)porphynato) manganese (III) chloride (2), and (5-(4-palmitoyloxyphenyl)-10,15,20-tris(3,5-di-tert-butyl-4-hydroxyphenyl)porphynato) manganese (III) chloride (3) in their aqueous suspensions were determined by the microcalorimetric method over the temperature range of 278–320K and in magnetic fields from 0 to 1T.MCE was positive for all complexes studied, i.e. the magnetic field impression under adiabatic conditions led to an increase in temperature of the complexes suspensions. MCE increased with an increase in the magnetic field induction at all temperatures studied. Dependences of MCE on temperature had weak maxima at 298K at all magnetic induction values. The disturbance of the intermolecular hydrogen-bonding of hydroxyl groups is one of probable reasons for such dependences type. MCE values increased under the palmitoyl substituent incorporation into one of the phenol groups at all temperatures.The heat capacity of the studied complexes rose slightly with temperature growth. Dependences of the heat capacity on temperature showed that the magnetic component of the heat capacity did not appear due to the presence of the manganese atom acting as a paramagnetic center in complexes 1, 2, and 3. The relation between the complexes structure and their magnetothermal properties was analyzed. It was justified that the changes of magnetothermal properties were caused by electronic substitution effects and, to an even greater degree, by the conditions of intermolecular hydrogen bonds formation in the paramagnetic materials.

Influence of Ag Additive to the Spacer Layer on the Structure and Giant Magnetoresistance of Electrodeposited Co/Cu Multilayers

In order to explore the possible surfactant effect of Ag on the formation of electrodeposited multilayers, Co/Cu(Ag) multilayers were prepared by this technique and their structure and giant magnetoresistance (GMR) were investigated. The multilayers were deposited from a perchlorate bath with various amounts of Ag+ ions in the solution for incorporating Ag atoms into the multilayer stack. Without Ag addition, secondary neutral mass spectroscopy (SNMS) indicated a well-defined composition modulation of the undermost Co/Cu bilayers. However, already at an Ag content as low as 1.8 at.% incorporated, SNMS showed a deterioration of the periodic multilayer structure. In agreement with the SNMS results, superlattice satellites were visible in the X-ray diffraction (XRD) patterns of the multilayers with up to 0.3 at.% Ag. The satellites were, however, very faint even for multilayers without Ag addition, indicating that the multilayers have high interface roughness and/or poor periodicity. In the absence of Ag and at the smallest Ag content investigated by XRD, a strong central multilayer peak and the weak superlattice satellites were complemented by weak diffraction maxima from non-periodic Co and Cu domains. In the Co/Cu(Ag) multilayer containing about 25 at.% Ag, i.e., nearly as much as Cu, XRD found a separate Ag(Cu) phase. In spite of the imperfect layered structure, a multilayer-type GMR behavior was observed in all samples up to about 10 at.% Ag incorporated in the multilayer stack. The GMR magnitude increased for Ag contents up to about 1 at.%, which implies that a small amount of Ag may have a beneficial effect through a slight modification of the layer growth and/or interface formation. However, for higher Ag contents beyond this level, the GMR was reduced in line with the structural degradation revealed by XRD and SNMS. For the highest Ag contents (above about 10 at.%), the GMR exhibited a behavior characteristic of a granular magnetic alloy, in agreement with the results of the structural study.

Synoptic Typing and Precursors of Heavy Warm-Season Precipitation Events at Montreal, Québec

Abstract A precipitation climatology is compiled for warm-season events at Montreal, Québec, Canada, using 6-h precipitation data. A total of 1663 events are recorded and partitioned into three intensity categories (heavy, moderate, and light), based on percentile ranges. Heavy (top 10%) precipitation events (n = 166) are partitioned into four types, using a unique manual synoptic typing based on the divergence of Q-vector components. Type A is related to cyclones and strong synoptic-scale quasigeostrophic (QG) forcing for ascent, with high-θe air being advected into the Montreal region from the south. Types B and C are dominated by frontogenesis (mesoscale QG forcing for ascent). Specifically, type B events are warm frontal and feature a near-surface temperature inversion, while type C events are cold frontal and associated with the largest-amplitude synoptic-scale precursors of any type. Finally, type D events are associated with little synoptic or mesoscale QG forcing for ascent and, thus, are deemed to be convective events triggered by weak shortwave vorticity maxima moving through a long-wave ridge environment, in the presence of an anomalously warm, humid, and unstable air mass that is conducive to convection. In general, types A and B feature the strongest dynamical forcing for ascent, while types C and D feature the lowest atmospheric stability. Systematic higher precipitation amounts are not preferential to any event type, although a handful of the largest warm-season precipitation events appear to be slow-moving type C (stationary front) cases.

Plasma potential mapping of high power impulse magnetron sputtering discharges

Pulsed emissive probe techniques have been used to determine the plasma potential distribution of high power impulse magnetron sputtering (HiPIMS) discharges. An unbalanced magnetron with a niobium target in argon was investigated for a pulse length of 100 μs at a pulse repetition rate of 100 Hz, giving a peak current of 170 A. The probe data were recorded with a time resolution of 20 ns and a spatial resolution of 1 mm. It is shown that the local plasma potential varies greatly in space and time. The lowest potential was found over the target’s racetrack, gradually reaching anode potential (ground) several centimeters away from the target. The magnetic presheath exhibits a funnel-shaped plasma potential resulting in an electric field which accelerates ions toward the racetrack. In certain regions and times, the potential exhibits weak local maxima which allow for ion acceleration to the substrate. Knowledge of the local E and static B fields lets us derive the electrons’ E×B drift velocity, which is about 105 m/s and shows structures in space and time.