Synthesis of ZnO and CuO nanoparticles via Sol gel method and Its Characterization by using XRD and FT-IR Analysis

Nanotechnology is a completely unique branch of technology that offers with substances in a very small size between (1-100 nm) with various crystal shapes which include spherical nanoparticles, flower shaped, Nano rods, Nano ribbons, and Nano platelets. Metals have ability to produce large number of oxides. These metal oxides play an major role in many areas of chemistry, physics, material science and food science. In this research, Zinc Oxide (ZnO) and Copper (II) oxide nanoparticles were synthesized via sol-gel process using zinc nitrate and copper (II) nitrate as precursor respectively. The characterization of CuO and ZnO nanoparticles was done by using various techniques. X-ray Diffraction (XRD) indicates the crystallinity and crystal size of CuO and ZnO nanoparticle. Fourier transform infrared spectroscopy (FT-IR) was used to get the infrared spectrum of the sample indicating composition of the sample which contains various functional groups. XRD result shows the particle size of CuO at highest peak 29.40140 was 61.25 nm and the particle size of ZnO at highest peak 36.24760 was 21.82 nm. FT-IR spectra peak at 594.56 cm-1 indicated characteristic absorption bands of ZnO nanoparticles and the broad band peak at 3506.9 cm-1 can be attributed to the characteristic absorption of O-H group. The analysis of FT-IR spectrum of CuO shows peaks at 602.09, 678.39, and 730.19cm−1 which refer to the formation of CuO. A broad absorption peak noticed at 3308.2 cm−1 attributed to O–H stretching of the moisture content.

Why the World Should Not Follow the Failed United States Model of Fighting Domestic Hunger

Many industrialized nations have followed the lead of the United States (US) in reducing workers’ wages and cutting government safety nets, while giving their populaces the false impression that non-governmental organizations can meet the food and basic survival needs of their low-income residents. The history of the last 50 years and the global COVID-19 pandemic demonstrate why that is a mistake, leading to vastly increased household food insecurity, poverty, and hunger. This paper takes a close look at US data to help to better understand the significant impact US federal government policy measures had on limiting hunger throughout the pandemic and how we can learn from these outcomes to finally end hunger in America and other developed nations. The top three policy prescriptions vital in ending household food insecurity in the US and industrialized countries are as follows: (1) to create jobs; raise wages; make high quality healthcare and prescription medicine free; and ensure that high quality childcare, education, transportation, and broad-band access are affordable to all; (2) to enact a comprehensive “Assets Empowerment Agenda” to help low-income people move from owing to owning in order to develop middle-class wealth; and (3) when the above two steps are inadequate, ensure a robust government safety net for struggling residents that provides cash, food, and housing assistance.

Non-linear coherent perfect absorption in the proximity of exceptional points

Coherent perfect absorption is one of the possibilities to get high absorption but typically suffers from being a resonant phenomena, i.e., efficient absorption only in a local frequency range. Additionally, if applied in high power applications, the understanding of the interplay of non-linearities and coherent perfect absorption is crucial. Here we show experimentally and theoretically the formation of non-linear coherent perfect absorption in the proximity of exceptional point degeneracies of the zeros of the scattering function. Using a microwave platform, consisting of a lossy nonlinear resonator coupled to two interrogating antennas, we show that a coherent incident excitation can trigger a self-induced perfect absorption once its intensity exceeds a critical value. Note, that a (near) perfect absorption persists for a broad-band frequency range around the nonlinear coherent perfect absorption condition. Its origin is traced to a quartic behavior that the absorbance spectrum acquires in the proximity of the exceptional points of the nonlinear scattering operator.

Particle Acceleration in Mildly Relativistic Outflows of Fast Energetic Transient Sources

Recent discovery of fast blue optical transients (FBOTs)—a new class of energetic transient sources—can shed light on the long-standing problem of supernova—long gamma-ray burst connections. A distinctive feature of such objects is the presence of modestly relativistic outflows which place them in between the non-relativistic and relativistic supernovae-related events. Here we present the results of kinetic particle-in-cell and Monte Carlo simulations of particle acceleration and magnetic field amplification by shocks with the velocities in the interval between 0.1 and 0.7 c. These simulations are needed for the interpretation of the observed broad band radiation of FBOTs. Their fast, mildly to moderately relativistic outflows may efficiently accelerate relativistic particles. With particle-in-cell simulations we demonstrate that synchrotron radiation of accelerated relativistic electrons in the shock downstream may fit the observed radio fluxes. At longer timescales, well beyond those reachable within a particle-in-cell approach, our nonlinear Monte Carlo model predicts that protons and nuclei can be accelerated to petaelectronvolt (PeV) energies. Therefore, such fast and energetic transient sources can contribute to galactic populations of high energy cosmic rays.

Long-duration seismicity and their relation to Copahue volcano unrest

Understanding seismic tremor wavefields can shed light on the complex functioning of a volcanic system and, thus, improve volcano monitoring systems. Usually, several seismic stations are required to detect, characterize, and locate volcanic tremors, which can be difficult in remote areas or low-income countries. In these cases, alternative techniques have to be used. Here, we apply a data-reduction approach based on the analysis of three-component seismic data from two co-located stations operating in different times to detect and analyze long-duration tremors. We characterize the spectral content and the polarization of 355 long-duration tremors recorded by a seismic sensor located 9.5 km SE from the active vent of Copahue volcano in the period 2012–2016 and 2018–2019. We classified them as narrow- (NB) and broad-band (BB) tremors according to their spectral content. Several parameters describe the characteristic peaks composing each NB episode: polarization degree, rectilinearity, horizontal azimuth, vertical incidence. Moreover, we propose two coefficients $$C_P$$ C P and $$C_L$$ C L for describing to what extent the wavefield is polarized. For BB episodes, we extend these attributes and express them as a function of frequency. We compare the occurrence of NB and BB episodes with the volcanic activity (including the level of the crater lake, deformation, temperature, and explosive activity) to get insights into their mechanisms. This comparison suggests that the wavefield of NB tremors becomes more linearly polarized during eruptive episodes, but does not provide any specific relationship between the tremor frequency and volcanic activity. On the other hand, BB tremors show a seasonal behavior that would be related to the activity of the shallow hydrothermal system. Graphical Abstract

Vibration Energy Harvesting by Means of Piezoelectric Patches: Application to Aircrafts

Vibration energy harvesters in industrial applications usually take the form of cantilever oscillators covered by a layer of piezoelectric material and exploit the resonance phenomenon to improve the generated power. In many aeronautical applications, the installation of cantilever harvesters is not possible owing to the lack of room and/or safety and durability requirements. In these cases, strain piezoelectric harvesters can be adopted, which directly exploit the strain of a vibrating aeronautic component. In this research, a mathematical model of a vibrating slat is developed with the modal superposition approach and is coupled with the model of a piezo-electric patch directly bonded to the slat. The coupled model makes it possible to calculate the power generated by the strain harvester in the presence of the broad-band excitation typical of the aeronautic environment. The optimal position of the piezoelectric patch along the slat length is discussed in relation with the modes of vibration of the slat. Finally, the performance of the strain piezoelectric harvester is compared with the one of a cantilever harvester tuned to the frequency of the most excited slat mode.

Role of different types of protective forest stands in fodder productivity of rangeland in the Western Caspian region

Forest pastures with different tree crown cover were studied. The seasonal dynamics of the yield and nutritional value of grass and twig-leaf fodder of forest pasture was studied. The unsystematic use of pastures in arid territories has increased the process of degradation and has become one of the factors of depletion of their natural vegetation. The use of forest reclamation in the 70s and 90s on sandy lands and pastures in the Western Caspian region made it possible to create significant areas of forest pasture land with strip and massive stands of Ulmus pumila L. and Robinia pseudoacacia L. Different types of tree stands created on pastures not only improve the microclimate and form a comfortable environment for grazing animals, but also are an additional source of valuable twig feed. The aim of the research was to study forage productivity of forest pastures with different types of plantings on the sands of the Western Caspian region. The objects of the research were forest pastures with different species composition and tree crown cover. Studies on the forage productivity of forest-reclaimed pastures were conducted in 2018-2020 on the basis of the North Caucasus branch of Federal Scientific Centre of Agroecology, Complex Melioration and Protective Af-forestation of the Russian Academy of Sciences. The research was based on field experiments and laboratory analyses. According to the results of the study, forest-reclaimed pastures with unsystematic grazing had 1.52-fold increase in productivity compared to natural ones. The largest amount of twig-leaf feed was formed in broad-band Robinia stands in summer-autumn period. The total gross stock of natural pastures of the Western Caspian region did not exceed 0.30.4 t/ha of dry weight, the consumed stock was 0.20.3 t/ha. With the help of strip and massive plantings on degraded pasture lands, it is possible to increase significantly their productivity and quality with the achievement of 7 MJ of exchange energy and 0.260.29 feed units in 1 kg of elm and robinia twig-leaf feed during droughts.

Astrophysical Neutrinos and Blazars

We review and discuss recent results on the search for correlations between astrophysical neutrinos and γ-ray-detected sources, with many extragalactic studies reporting potential associations with different types of blazars. We investigate possible dependencies on blazar sub-classes by using the largest catalogues and all the multi-frequency data available. Through the study of similarities and differences in these sources we conclude that blazars come in two distinct flavours: LBLs and IHBLs (low-energy-peaked and intermediate-high-energy-peaked objects). These are distinguished by widely different properties such as the overall spectral energy distribution shape, jet speed, cosmological evolution, broad-band spectral variability, and optical polarisation properties. Although blazars of all types have been proposed as neutrino sources, evidence is accumulating in favour of IHBLs being the counterparts of astrophysical neutrinos. If this is indeed the case, we argue that the peculiar observational properties of IHBLs may be indirectly related to proton acceleration to very high energies.