Imprinting the complex dielectric permittivity of liquids into the spintronic terahertz emission

We report an approach in time-domain terahertz (THz) spectroscopy for measuring the dielectric response of liquids based on inherent properties of spintronic THz emitters (STEs). The THz electric field radiated from the STE is inversely proportional to the sum of the complex refractive indices of the media surrounding the thin metallic stack of the STE and the stack's conductivity. We demonstrate that by bringing a liquid in contact with the emitter, its complex refractive index and accordingly its dielectric response are imprinted into the radiated electromagnetic field from the emitter. We use water as the test liquid and ascertain its dielectric loss and permittivity in the range of ∼0.3–15 THz

Time-resolved terahertz–Raman spectroscopy reveals that cations and anions distinctly modify intermolecular interactions of water

The solvation of ions changes the physical, chemical and thermodynamic properties of water, and the microscopic origin of this behaviour is believed to be ion-induced perturbation of water’s hydrogen-bonding network. Here we provide microscopic insights into this process by monitoring the dissipation of energy in salt solutions using time-resolved terahertz–Raman spectroscopy. We resonantly drive the low-frequency rotational dynamics of water molecules using intense terahertz pulses and probe the Raman response of their intermolecular translational motions. We find that the intermolecular rotational-to-translational energy transfer is enhanced by highly charged cations and is drastically reduced by highly charged anions, scaling with the ion surface charge density and ion concentration. Our molecular dynamics simulations reveal that the water–water hydrogen-bond strength between the first and second solvation shells of cations increases, while it decreases around anions. The opposite effects of cations and anions on the intermolecular interactions of water resemble the effects of ions on the stabilization and denaturation of proteins

Use of Probiotics as Growth Promoters and Immunostimulators in Fingerlings of Cyprinid Fish Species

Intensive aquaculture production has required the development of an individual’s resistance to disease rather than depending upon antibiotics or chemotherapeutics. The role of gastrointestinal microflora in disease resistance has been established in many fish species, which has led to the concept of manipulating gastrointestinal microflora for better health management. A number of studies has been conducted in different fish species with various useful microorganisms called ‘probiotics’ to amplify gastrointestinal microflora to fight against various infectious diseases. Probiotics are beneficial microorganisms which protect the host from diseases. Probiotic protection can be achieved by various mechanisms. Most probiotics used in aquaculture belong to the lactic acid bacteria, the genus Bacillus, the photosynthetic bacteria, the yeast, notwithstanding other genera and species have also been used. The immunostimulatory effect of probiotics has been established in many fish species, but their direct involvement in the immune response is not well established. It has also been proven that the application of probiotics in aquaculture has beneficial effects on growth of fish as well as on the environment. At present, data about the efficacy of probiotics in commercial aquaculture of Serbia is still lacking. This review discusses mainly the studies and applications about effects, problems and perspectives of probiotics used in fingerlings of cyprinid fish species, and highlights immunostimulatory effects and growth promotion effects of commercial probiotic products. In the present paper the results that show positive influence of probiotics in cyprinides nutrition on production performance and immune system are summarized. Special accent is given to criteria for proper selection of probiotics in cyprinides production

Phase-Sensitive Vibrational Sum and Difference Frequency-Generation Spectroscopy Enabling Nanometer-Depth Profiling at Interfaces

The unique physical and chemical properties of interfaces are governed by a finite depth that describes the transition from the topmost atomic layer to the properties of the bulk material. Thus, understanding the physical nature of interfaces requires detailed insight into the different structures, chemical compositions, and physical processes that form this interfacial region. Such insight has traditionally been difficult to obtain from experiments, as it requires a combination of structural and chemical sensitivity with spatial depth resolution on the nanometer scale. In this contribution, we present a vibrational spectroscopic approach that can overcome these limitations. By combining phase-sensitive sum and difference frequency-generation (SFG and DFG, respectively) spectroscopy and by selectively determining different nonlinear interaction pathways, we can extract precise depth information and correlate these to specific vibrationally resonant modes of interfacial species. We detail the mathematical framework behind this approach and demonstrate the performance of this technique in two sets of experiments on selected model samples. An analysis of the results shows an almost perfect match between experiment and theory, confirming the practicability of the proposed concept under realistic experimental conditions. Furthermore, in measurements with self-assembled monolayers of different chain lengths, we analyze the spatial accuracy of the technique and find that the precision can even reach the sub-nanometer regime. We also discuss the implications and the information content of such depth-sensitive measurements and show that the concept is very general and goes beyond the analysis of the depth profiles. The presented SFG/DFG technique offers new perspectives for spectroscopic investigations of interfaces in various material systems by providing access to fundamental observables that have so far been inaccessible by experiments. Here, we set the theoretical and experimental basis for such future investigations

Powder Bed Fusion Additive Manufacturing Using Critical Raw Materials: A Review.

The term "critical raw materials" (CRMs) refers to various metals and nonmetals that are crucial to Europe's economic progress. Modern technologies enabling effective use and recyclability of CRMs are in critical demand for the EU industries. The use of CRMs, especially in the fields of biomedicine, aerospace, electric vehicles, and energy applications, is almost irreplaceable. Additive manufacturing (also referred to as 3D printing) is one of the key enabling technologies in the field of manufacturing which underpins the Fourth Industrial Revolution. 3D printing not only suppresses waste but also provides an efficient buy-to-fly ratio and possesses the potential to entirely change supply and distribution chains, significantly reducing costs and revolutionizing all logistics. This review provides comprehensive new insights into CRM-containing materials processed by modern additive manufacturing techniques and outlines the potential for increasing the efficiency of CRMs utilization and reducing the dependence on CRMs through wider industrial incorporation of AM and specifics of powder bed AM methods making them prime candidates for such developments