Periodic Changes Research Articles

Why is binding of a divalent metal cation to a structural motif containing four carboxylate residues not accompanied by a conformational change?

We earlier showed that Torpedo californica acetylcholinesterase (AChE) contains a cluster of four conserved aspartates that can strongly bind divalent cations, which we named the 4D motif. Binding of the divalent metal cations greatly increases its thermal stability. Here we systematically examined all available crystallographic structures of T. californica AChE. Two additional metal-binding sites were identified, both composed of acidic and histidine residues. Relative binding to the 4D and additional sites was studied using metadynamics simulations. It was observed that in crystal structures devoid of metal ions in the 4D site, the conformation of T. californica AChE is almost identical to that in structures in which it is occupied by a divalent metal ion. Closer examination of the 4D motif reveals that three of the four acidic residues form ion pairs with conserved basic residues surrounding them. We named this new motif the 4A/3B motif. Molecular dynamics with quantum potential simulations was used to quantify the 4D motif's binding strength compared with that of the metal-binding site in the protein fXIIIa, which consists of four aspartates, but is devoid of adjacent cationic residues. Whereas fXIIIa's 4D site, in the absence of a metal cation, expanded significantly in the simulation, that of Torpedo AChE displayed only minor periodic changes in size. Furthermore, the energy of metal ion unbinding from the two sites differs by ca. 10 kcal/mol. We identified several other proteins in the PDB that contain the 4A/3B motif, whose conformations are identical in the presence or absence of a metal ion. An animated Interactive 3D Complement (I3DC) is available in Proteopedia at https://proteopedia.org/w/Journal:Protein_Science:4.

Orexin concentrations and diurnal variation in the cerebrospinal fluid of intensive care unit patients undergoing aortic surgery with spinal drainage.

Cerebrospinal fluid (CSF) levels of orexin show a cyclic diurnal variation in healthy subjects, which is diminished in patients with certain diseases. However, possible circadian variations in orexin levels in critically ill patients remain unknown. In this study, we evaluated the orexin concentrations in the CSF and their diurnal variation in patients undergoing thoracic aortic aneurysm repair with lumbar intrathecal catheterization for CSF drainage after non-neurosurgery. Eligible patients with a lumbar intrathecal catheter placed for CSF drainage following aortic surgery at a single-center ICU between September 2019 and February 2020 were included. Catheters were placed before anesthesia induction, and CSF was collected at the time of catheter placement, ICU admission, and daily at 6:00, 12:00, 18:00, and 24:00 until the catheter was removed or for up to 5 days after admission to the ICU. Three patients (Patients A, B, and C) who underwent thoracic aortic aneurysm repair were included. Patients B and C received sedatives or hypnotics during the orexin measurement period. The baseline orexin levels for Patients A, B, and C were 219.9, 312.3, and 403.8 pg/mL, while the mean orexin levels were 319.4 ± 82.6, 372.4 ± 56.0, and 306.3 ± 48.3 pg/mL, respectively. For all three patients, orexin levels showed diurnal variations, but no consistent periodic changes. CSF orexin concentrations for patients undergoing thoracic aortic aneurysm repair in the ICU were within the reported range compared to those of previously reported healthy subjects; however, consistent periodic diurnal variations were not observed.

Experimental Investigation of the Yaw Misalignment Effect on the Power Performance and System Loading of a Flapping‐Foil Hydrokinetic Turbine

ABSTRACTHydrokinetic turbines (HTs) extract power by utilizing hydrodynamic forces from flow energy. The surplus load not used for power generation acts as a system load and must be considered when designing the turbine. Additionally, due to the variability of the flow direction during tidal power generation, the effect of the yaw misalignment angle on the power generation performance and system loading is an important design consideration. This study investigates the characteristics of an experimental model of an HT that uses two flapping foils, at different yaw misalignment angles through circulating water tunnel experiments. Experimental results show that with a yaw angle change of 10°, the power performance decreases by approximately 10% and the load increases by about 30% compared to an aligned configuration. Notably, the load in the flow‐perpendicular direction was significant, with periodic changes due to repetitive up‐and‐down motions. Consequently, the hydrodynamic force characteristics of the HT differ from those of conventional rotary turbines, necessitating the development of a design method that fits these characteristics for the actual installation of flapping‐foil HTs at tidal current power generation sites.

Methods of Balancing Technological Systems of Multiproduct Production

The functioning of the machine-building industry has its specifics, particularly periodic changes in the range (size, configuration, and others) of manufactured products. In addition, it is essential to consider the need to reduce the time spent on the production of each unit. Almost continuous changes in technology, failures in the supply of raw materials, uncoordinated logistics, and many other factors often cause significant and unproductive costs, leading to an increase in the technological stage. The most promising direction to reduce the technological time of manufacturing products by multiproduct enterprises is to reduce the waiting time owing to the uniform distribution of each technological transition according to the state of the available workshop equipment (plant, production area, enterprise). This study proposes a novel model of technological systems that enables the adaptation of technological processes for part manufacturing and comprises data structures that define their technical capabilities. The proposed algorithm facilitates a reduction in downtime and an increase in equipment utilization factor. It is possible to optimize the technological processes that change the structure of each production operation to adapt to the existing technology. Testing this methodology demonstrated a significant increase of 8% in the process utilization rate of machinery.

DGTNet：dynamic graph attention transformer network for traffic flow forecasting

Abstract Graph-based traffic flow prediction plays a crucial role in urban traffic management and planning. In this paper, we propose a novel Dynamic Graph Attention Transformer Network (DGTnet), which is designed to address the issue of inadequately integrating of temporal and spatial dimensions in traditional models. DGTnet maintains temporal continuity while revealing the complex dynamic relationships between key nodes in the urban traffic system, capturing the periodic changes in the rhythm of city life. Specifically, this study adopts adaptive signal decomposition technology to decompose traffic data into multiple intrinsic mode functions (IMFs), effectively capturing the dynamic changes in traffic flow. This decomposition method is key to the implementation of DGTnet dynamic graph construction, enabling the analysis of traffic flow at different time scales, thereby providing a new perspective for traffic flow prediction research. In the traffic prediction module, we comprehensively consider node, edge, and graph structural information, adopting a multi-head self-attention mechanism to achieve direct cross-modeling in both temporal and spatial dimensions. Finally, we introduce a position-wise feed forward network layer to integrate different types of data and capture nonlinear relationships. The experimental results, based on the public transportation network data sets METR_LA, PEMS_BAY, PEMS03 and PEMS07, demonstrate that DGTNet exhibits notable enhancements in three evaluation indicators, namely the Mean Absolute Percentage Error (MAPE), the Root Mean Square Error (RMSE) and the Mean Absolute Error (MAE). The pertinent code has been made available for public access at https://github.com/chenjing0616/DGTNet.

The Mesoscopic Damage Mechanism of Jointed Sandstone Subjected to the Action of Dry–Wet Alternating Cycles

The effect of the dry–wet cycle, characterized by periodic water level changes in the Three Gorges Reservoir, will severely degrade the bearing performance of rock formations. In order to explore the effect of the dry–wet cycle on the mesoscopic damage mechanism of jointed sandstone, a list of meso-experiments was carried out on sandstone subjected to dry–wet cycles. The pore structure, throat features and mesoscopic damage evolution of jointed sandstone with the action of the dry–wet cycle were analyzed using a-low-field nuclear magnetic resonance (NMR) technique. Subsequently, the impact on the mineral content of dry–wet cycles was studied by small angle X-ray scattering (SAXS). Based on this, the mesoscopic damage mechanism of sandstone subjected to dry–wet cycles was revealed. The results show that the effects of the drying–wetting cycle can promote the development of porous channels within sandstone, resulting in cumulative damage. Besides, with an increase in dry–wet cycles, the proportion of small pores and pore throats decreased, while the proportion of medium and large pores and pore throats increased. The combined effects of extrusion crush, tensile fracture, chemical reaction and dissolution of minerals inside the jointed sandstone contributed to the development of mesoscopic pores, resulting in the increase of porosity and permeability of rock samples under the dry–wet cycles. The results provide an important reference value for the stability evaluation of rock mass engineering under long-term dry–wet alternation.

Integrative analysis of the transcriptome, targeted metabolome, and anatomical observation provides insights into the brassinosteroids-mediated seasonal variation of cambial activity in Chinese fir

Chinese fir (Cunninghamia lanceolata) is widely planted in southern China due to its strong adaptability and fast-growing. Wood formation is derived from the periodic changes of cambial activity that is regulated by environmental cues and phytohormone signals. Brassinosteroids (BRs), a class of plant-specific steroid hormones, play central roles in modulating cambial activity and xylem development. To decipher the regulatory role of BR in the dynamic change of Chinese fir cambium, a comprehensive analysis of the transcriptome, targeted metabolome, and anatomical observation was conducted. The application of 24-epibrassinolide (EBR, 10 μM) significantly increased the cambial cell layers, resulting in the thickening of the secondary xylem. Conversely, brassinazole (Brz) treatment strikingly inhibited the xylem development by attenuating cambial activity. Moreover, 1583 up-regulated differentially expressed genes (DEGs) were shared in stages A (reactivating), C (active), and E (dormant), which were annotated into the xylem formation and BR signaling pathway. Metabolomic profiling of phytohormone indicated that the contents of brassinolide (BL, the most active BR), castasterone (CS), and typhasterol (TY) were distinctly increased in stage C. Furthermore, ClBES1/BZR1, a hub gene in the co-expression network, dramatically activated the expression of ClPAL2 and ClMYB4 by binding to their promotors. Collectively, these results elucidate the potential role of BR in dynamic changes in the cambial zone and provide insight into the regulatory mechanism of wood formation in conifers.

Laser ablation inductively coupled plasma mass spectrometry measurements for high-resolution chemical ice core analyses with a first application to an ice core from Skytrain Ice Rise (Antarctica)

Abstract. Conventional methods of inorganic impurity analysis do not provide high enough depth resolution for many scientific questions in ice core science. In this study, we present a setup of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for high-resolution glacier ice impurity analysis to the sub-millimetre scale. This setup enables ice core chemical impurity analysis to a depth resolution of ∼182 µm while consuming only very small amounts of ice. The system performs simultaneous analysis of sodium, magnesium and aluminium incorporated in the ice matrix. In this case study within the framework of the WACSWAIN (WArm Climate Stability of the West Antarctic Ice Sheet in the last INterglacial) project, our method is applied to a selection of samples from the Skytrain ice core (West Antarctica) over a total length of 6.7 m consisting of about 130 single samples. The main goal of this study is to use the new LA-ICP-MS method to extract meaningful climate signals on a depth resolution level beyond the limits of continuous-flow analysis (CFA). A comparison between low-resolution CFA data and the high-resolution LA-ICP-MS data reveals generally good agreement on the decimetre scale. Stacking of parallel laser measurements together with frequency analysis is used to analyse the high-resolution LA-ICP-MS data at millimetre resolution. Spectral analysis reveals that despite effects of impurity accumulation along ice crystal grain boundaries, periodic concentration changes in the Skytrain ice core on the millimetre scale can be identified in ice from 26.8 ka (kiloyears before present, i.e. 1950 CE). These findings open new possibilities for climate data interpretation with respect to fast changes in the last glacial period and beyond, for example within the Beyond EPICA oldest-ice project.

Forced Vibration Induced by Dynamic Response Under Different Inlet Distortion Intensities

Boundary layer ingestion propulsion systems have attracted much attention due to their significant potential to reduce the fuel consumption of future commercial aircraft. However, the aeroelastic stability of the fan blade is affected by the continuous non-uniform incoming flow induced by the ingestion of the boundary layer. When the fan blades rotate in the junction area between the distorted area and the clean area, blade pressure fluctuations occur. This phenomenon triggers a dynamic response process in the blade. Previous numerical investigations explored the influence of the distorted inflow on the blade vibration amplitude, and found that there are two sources of low-order excitation to the blades: the distorted inflow and the dynamic response of the blade. The results show that the low-order excitation existing in the distorted inflow varies sinusoidally with the distortion extent. However, as a new source of excitation, the key influence mechanism of dynamic response is still unclear. To explore this issue, calculations and analyses were conducted for different distorted inflow intensities. The results show that the blade vibration amplitude increases with the rise in distortion intensity. The total pressure at the leading and trailing edge of the rotor blade was extracted for analysis. It was found that when the blade enters or leaves the distorted area, there is a consistent lag in the change in total pressure at the trailing edge compared to the leading edge. This lag leads to an abrupt variation in the total pressure ratio, which constitutes the dynamic response process of the rotor blade. This periodic change generates a second-order excitation that causes the blade to vibrate.

Widening of wind-stress anomalies amplifies ENSO in a warming climate

Abstract Climate change simulations generally indicate the strengthening of El Niño Southern Oscillation (ENSO) sea surface temperature (SST) variability through the 21st century, yet a robust physical mechanism explaining this change across different models is still lacking, and the projections for ENSO amplitude exhibit a large spread. Most commonly, changes in the background state of the tropical Pacific are invoked to explain these changes of ENSO. Here we show that changes in the structure of wind-stress anomalies associated with ENSO are potentially as important as these background state changes. Specifically, changes in the magnitude, meridional width, and zonal structure of wind-stress anomalies can explain approximately 53% of the inter-model variance in the projected change of ENSO magnitude through the 21st century as well as 43% in ENSO periodicity changes. Among these changes in the wind structure, the meridional widening of wind anomalies plays the most important role. To demonstrate that these changes are indeed critical, we develop a hybrid model of ENSO based on the Community Earth System Model version 2, which incorporates a dynamical ocean coupled to a simplified statistical atmosphere within the tropical Pacific. In the absence of external forcing and corresponding mean-state changes, the imposed changes in wind stress anomalies in this hybrid model result in an increase of ENSO amplitudes of nearly 10% along the equator. Our results are also theoretically supported by a recharge-oscillator model that incorporates the meridional wind structure. Thus, changes in the structure of wind-stress anomalies, together with changes in the mean state, likely play a critical role in the projected strengthening of ENSO.

On the two approaches for the combustion instability predictions in a long-flame combustor

This paper presents a detailed comparative analysis and discussion of two typical predictive methods for combustion instability in long flame combustion chambers: the coupled method and the decoupled method. Using large eddy simulation (LES), the coupled method directly predicts stability in typical long flame combustion chambers. In the decoupled method, stability in the combustion chamber is predicted by combining a low-order acoustic network for long flames with flame responses and mean parameters from numerical simulations. The research results indicate that the coupled method provides full-field information, while the decoupled method neglects certain factors, such as the coupling between combustion and acoustics. However, the decoupled method can directly determine combustion instability based on the growth rate of oscillation modes. The flow field undergoes periodic changes, with the region of fluctuation in the combustion heat release rate gradually increasing, resembling vortex development, which ruptures upon encountering the wall due to radial constraints. Furthermore, in the decoupled method, the periodic changes in the flow field are controlled by the frequency of incoming flow disturbances, whereas in the coupled method, they are controlled by the acoustic frequency of the combustion chamber. In the coupled method, the coupling among disturbances and the acoustic disturbances at the boundaries amplifies the disturbances, causing the radial scale of the fluctuation region in the combustion heat release rate to increase along the axial direction and approach a fixed value faster than in the decoupled method.

A study on the internal vortex structure within a single-blade pump via numerical methods and particle image velocimetry experiments

This study investigates the performance and internal flow characteristics of a single-blade centrifugal pump through a comprehensive analysis integrating performance tests, Particle Image Velocimetry (PIV) tests, and numerical simulations. Across the operational speed range of 1470–2940 rpm, the predicted pump (head-flow rate curve)performance error between the numerical simulation results and the test results of the pump underrated flow conditions is found to be only 3.4%, demonstrating the high accuracy of the selected numerical method in predicting both performance metrics and internal flow structures. Key findings highlight the presence of significant circumferential and axial secondary flows in the region where the blade wraps back, resulting in the formation of high-intensity vortex structures and subsequent energy dissipation. The interaction of the blade's trailing jet with the volute casing's tongue induces periodic changes in the intensity and spatial size of these vortex structures. Furthermore, pronounced reverse vortex pairs are identified within the volute casing, attributed to axial non-uniformity in impeller outflow. These vortex pairs are associated with the preferential accumulation of solid particles, potentially contributing to wear in the volute casing of single-blade centrifugal pumps. The revelation of the evolution characteristics of vortex structure in single-blade centrifugal pumps provides theoretical support for reducing pressure pulsation and radial force of single-blade centrifugal and provides a potential solution to the technical difficulties of low efficiency and poor stability of single-blade centrifugal pumps. Overall, this study provides valuable insights into optimizing the design and operational efficiency of single-blade centrifugal pumps by elucidating their complex flow dynamics and performance characteristics under varying operational conditions.

Molecular dynamics of deformation and fragmentation processes in liquid droplets under pulsed electric field

The deformation and breakup of droplets are widely observed in various aspects of production and daily life. Using molecular dynamics simulations, this study primarily investigated the deformation and breakup of droplets in a nitrogen environment under pulsed electric fields of different frequencies. The results indicate that the droplet deformation undergoes periodic changes under the influence of the pulsed electric field. At equivalent electric field strengths, droplets are more likely to break under a 6.25 GHz pulsed electric field compared to a 25 GHz pulsed electric field, where droplet deformation remains stable without breaking. At every frequency, the bond energy of water molecules consistently decreases. The solvent-accessible surface area changes with the electric field at 6.25 GHz. Furthermore, the minimum value of hydrogen bond quantity reached under high-frequency pulsed fields is higher than that under low-frequency fields. The change in hydrogen bond quantity is inversely proportional to the solvent-accessible surface area. These findings provide insights into the microscopic mechanisms of droplet deformation and breakup, offering a reference for future studies.

Origin of Ca II emission around polluted white dwarfs

Dozens of white dwarfs with anomalous metal polluted atmospheres are currently known to host dust and gas discs. The line profiles of the Ca II triplet emitted by the gas discs show a significant asymmetry. In recent decades, researchers have also discovered several minor planets orbiting such white dwarf stars. The most challenging burden of modelling gas discs around metal polluted white dwarfs is to simultaneously explain the asymmetry and metal pollution of the star's atmosphere over a certain period of time. Furthermore, models should also be consistent with other aspects of the observations, such as the morphology of the emission lines. This paper aims to construct a self-consistent model to explain the simultaneous white dwarf pollution and Ca II line asymmetry over at least three years. In our model, an asteroid disintegrates in an eccentric orbit, periodically entering below the star's Roche limit. The debris resulting from the disintegration sublimates at a temperature of 1500 K, producing gas that viscously spreads to form a disc. The evolution of the disc is studied over a period of 1.2 years (over 21000 orbits) using two-dimensional hydrodynamic simulations. Synthetic Ca II line profiles are calculated using the surface mass density and velocity distributions provided by the simulations, taking into account for the first time the asymmetric velocity distribution in the disc. An asteroid disintegrating on an eccentric orbit gives rise to the formation of an asymmetric disc and asymmetric Ca II triplet emission. Our model can explain the periodic reversal of the redshifted and blueshifted peak of the Ca II lines caused by the precession of the disc on timescales of 10.6 to 177.4 days. Our work suggests that the persistence of Ca II asymmetry over decades and its periodic change in the peaks can be explained by asteroids on eccentric orbits in two scenarios. In the first case, the asteroid disrupts on a short timescale (a couple of orbits), and the gas has a low viscosity range ($0.001< to maintain the Ca II signal for decades. In the other scenario, the asteroid disrupts on a timescale of a year, and the viscosity of the gas is required to be high, $

Variation Characteristics of Actual Evapotranspiration and Uncertainty Analysis of Its Response to Local Climate Change in Arid Inland Region of China

Exploring the variation characteristics of actual evapotranspiration (ETa) and its response to climate change in the arid inland region of China is of great significance for strengthening regional water resources management and maintaining ecological environment security and stability. Taking the Dulan River Basin as the research area, based on the meteorological data from the Wulan Station and hydrological data from the Shanggaba Station from 1981 to 2020, the variation characteristics of ETa at the annual scale were analyzed. The ETa estimation model and joint distribution model of P and potential evapotranspiration (ET0) was constructed based on climate factors, and the uncertainty of ETa response to climate change was explored with the water balance method, multiple linear regression, marginal distribution function, Copula function, and Monte Carlo algorithm. The results showed that the multi-year mean value of ETa in the study area was 261.6 mm, and the interannual process showed an insignificant upward trend, and had no abrupt change during the period. There were two obvious main cycles, which were 19-year periodic changes on the 30-year time scale and 6-year periodic changes on the 9-year time scale. The ETa estimation model based on precipitation (P) and ET0 had good simulation accuracy. The optimal marginal distributions of P and ET0 were Pearson-III (P-III) distribution and Generalized Extreme Value (GEV) distribution, respectively. The Copula joint distribution probability density of P and ET0 was a symmetric saddle-shaped distribution. ETa showed an inverted ‘S’ distribution with the change in joint guarantee rate of P and ET0, ranging from 116.9 mm to 498.6 mm. ETa was an interval range under a certain joint guarantee rate. The research results can provide support for the assessment of ETa, and help to further understand the driving mechanism of climate change on ETa in the arid inland region of China.

Controlling the initial separation distance between two electron plasma vortices in a Malmberg–Penning trap

This paper presents a novel method to continuously control the initial separation distance d between two plasma vortices of electrons. In this method, the two electron columns are initially confined individually in two coaxial Malmberg–Penning traps with different axial lengths. They rotate around the trap axis at different rotation frequencies due to the \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\varvec{E}\ imes \\varvec{B}$$\\end{document} drift. Their different rotation rates cause periodic changes in their relative azimuthal positions. The initial conditions are established when the two columns are stretched along magnetic field lines of a unified Malmberg–Penning trap. This method precisely provides a simple and continuous adjustment of the initial d and facilitates efficient investigation of the interaction of the two plasma electron vortices.

Analysis of Optimal Water Levels in the Great Lakes Based on A Comprehensive Satisfaction Function

The purpose of this paper is to analyze the optimal water levels in the Great Lakes to meet the needs of multiple stakeholders and thus achieve sustainable development in the region. The Weight-Function-Synthesis-Optimization (WFSO) model was used in this study. By classifying the water level needs of different interest groups, their respective satisfaction functions are established, and the overall satisfaction function is formed by weighting. In addition, the quadratic polynomial function is used to fit the optimal monthly water level time series of Lake Ontario, and the fitting effect is good, fully reflecting the periodic and seasonal changes in the water level of Lake Ontario. By considering the priorities of various stakeholders, this paper defines an overall satisfaction metric, "allsa," and identifies a time series of monthly optimal water levels for Lake Ontario and beyond. The ideal water level was determined to be 74.9 meters. The study results suggest that maintaining this water level can maximize the satisfaction of ecosystems, transportation, real estate, terminals, and hydropower companies, and promote sustainable development of the region.

Sociohistorical context and post-prison life course

Life-course criminology has recently begun to focus on sociohistorical context, with the use of multi-cohort studies. However, those studies have mostly concentrated on aggregate crime rates. Desistance research, in turn, has largely overlooked the impact of the broader sociohistorical context. Based on recent work on the effect of sociohistorical context on crime rates, we propose that context may shape desistance and social reintegration in a nuanced way.We examined employment, housing, and marriages among Finnish first-time prisoners released between 1995 and 2014 (N = 23,350) until 2019. We quantified the link between selected macro-level indicators and these outcomes using age-period-cohort models.The results showed that the outcomes evolved in separate ways post-release. Employment and marriage became more common over time, but only employment showed distinct periodical changes. The probability of living in housing remained stable. A higher level of national unemployment was associated with all outcomes. The association between prisoner characteristics and the outcomes changed depending on release year.Post-prison societal integration should not be assessed by one measure alone. Desistance studies should address societal context when comparing different times or countries. Early studies may require replication if the associations between demographic factors and desistance outcomes are subject to change.

Assessment of the Drought Risk in Constanta County, Romania

Drought poses a significant risk in many parts of the world, especially in regions reliant on agriculture. Evaluating this risk is an essential step in preventing and reducing its impact. In this context, we assess the drought intensity at six sites in Constanța County (Romania) using the de Martonne aridity index. The risk of aridity and vulnerability to drought were evaluated by the Drought Hazard Index (DHI) and Drought Risk Index (DRI), computed based on the Standardized Precipitation Index (SPI). The de Martonne index indicates a variation between the slightly arid and semi-arid climates for Adamclisi station, with periodic changes from semi-arid to arid. At Cernavodă station, we notice a passage from an arid period towards a moderately humid one (in 2005), followed by a movement in the opposite direction to the limit of the arid zone (in 2011), and a return inside the “limits” of the semi-arid to moderately arid climate. A similar variation for 2000–2018 is noticed at Medgidia, Hârșova, and Mangalia. DRI classifies two stations in the low risk to drought category and one in the moderate risk to drought class. The other two locations experience a high or very high risk of drought. The drought intensities varied in the intervals 0.503–1.109 at Constanța, 0.473–1.363 at Mangalia, 0.511–1.493 at Adamclisi, 0.438–1.602 at Hârșova, 0.307–1.687 at Medgidia, and 0.463–1.307 at Cernavodă, and the prolonged drought periods were over 99 months at all stations.

Spin-Dependent Regulation of The Electronic and Magnetic Properties of Poly(3-Alkylthiophene) Oligomers and Their Composites with Aromatic Nanoadditives

The energy and spin parameters of poly(3-alkylthiophene) oligomers and their composites with aromatic hydrocarbons are calculated. The coexistence of polarons with different degrees of delocalization in the studied compounds has been identified. Periodic changes in the electronic and spin properties of composites were detected, initiated by the interaction of oligomers with aromatic nanoadditives. The anisotropic parameters of the spin Hamiltonians of the studied systems are obtained and their high-resolution EPR spectra are calculated.