Analysis of energy consumption bounds in CMOS current-steering digital-to-analog converters

Analog Integrated Circuits and Signal Processing - In this paper, an attempt to estimate energy consumption bounds versus signal-to-noise ratio (SNR) and spurious-free dynamic range (SFDR) in CMOS...     

Upgrading biogas produced at dairy farms into renewable natural gas by methanation

Renewable natural gas can be produced from raw biogas, a product of the anaerobic decomposition of organic material, by upgrading its CO₂ content (25‐50%) via thermocatalytic hydrogenation (CO₂ methanation). The H₂ needed for this reaction can be generated by water electrolysis powered by carbon emission‐free energy sources such as renewable or nuclear power, or using surplus electricity. Herein, after briefly outlining some aspects of biogas production at dairy farms and highlighting recent developments in the design of methanation systems, a case study on the renewable natural gas generation is presented. The performance of a system for renewable natural gas generation from a 2000‐head dairy farm livestock manure is evaluated and assessed for its economic potential. The project is predicted to generate revenue through the sale of energy and carbon credits with the payback period of 5 years, with a subsidized energy price.     

The study on the impact of glycated pea proteins on human intestinal bacteria

The traditionally perceived function of nutrition includes supplying the consumer with the appropriate quantity and quality of substrates. As nutritional substrates, proteins are prone to spontaneously occurring non-enzymatic glycosylation (glycation) which can alter their molecular structure, making them highly bioactive. Glycated food proteins are able to modify the bacterial intestinal ecosystem, which is of great importance for the optimal usage of nutrients and maintenance of both intestinal homeostasis and balanced health status of the consumer. This study aimed to determine the impact of glycated pea proteins on the intestinal bacteria from a healthy human. The analyses were conducted with the use of experimental batch-type simulator models imitating human intestinal conditions. The glycated pea proteins affected the growth of gut commensal bacteria, particularly lactobacilli and bifidobacteria, whose levels increased significantly. There was a corresponding shift in the bacterial metabolites with increased levels of the short chain fatty acids (SCFAs); acetate, propionate lactate and butyrate. Intestinal bacteria were able to utilize these pea proteins thus indicating that the energy encrypted in glycated pea proteins, partially inaccessible for gastric enzymes, may be salvaged by gut microbiota. Such changes in microbial composition may beneficially impact the intestinal environment and exert a health-promoting effect in humans.     

Shungite/poly(vinyl alcohol) hybrid hydrogels: An efficient adsorption material for rare earth metals in aqueous media

Rare earth elements play a pivotal role in modern technologies, thereby driving an escalating demand for their procurement. To effectively extract these elements from aqueous solutions, it is imperative to explore innovative sorbent materials. In this context, a hydrogel sorbent material was developed by employing poly(vinyl alcohol) (PVA) and shungite—an economical, naturally occurring, easily processable, and sustainable material. This was achieved through the freezing–thawing method, employing sodium borate as a crosslinking agent. The physicochemical characteristics of the hydrogels were determined through scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) analysis, Zetasizer analysis, and elemental analysis. The shungite-incorporated PVA hydrogels displayed notable characteristics, including a substantial swelling capacity of 61% and a specific surface area of 32.8 m²/g. Most significantly, these hydrogels exhibited a remarkable affinity for La³⁺ ions, with an uptake ratio of 134 mg/g. This was followed by Nd³⁺, Dy³⁺, and Er³⁺ ions, which displayed uptake ratios of 79, 74, and 73 mg/g, respectively.     

Elemental and organic carbon in aerosols over urbanized coastal region (southern Baltic Sea, Gdynia)

Studies on PM 10, total particulate matter (TSP), elemental carbon (EC) and organic carbon (OC) concentrations were carried out in the Polish coastal zone of the Baltic Sea, in urbanized Gdynia. The interaction between the land, the air and the sea was clearly observed. The highest concentrations of PM 10, TSP and both carbon fractions were noted in the air masses moving from southern and western Poland and Europe. The EC was generally of primary origin and its contribution to TSP and PM 10 mass was on average 2.3% and 3.7% respectively. Under low wind speed conditions local sources (traffic and industry) influenced increases in elemental carbon and PM 10 concentrations in Gdynia. Elemental carbon demonstrated a pronounced weekly cycle, yielding minimum values at the weekend and maximum values on Thursdays. The role of harbors and ship yards in creating high EC concentrations was clearly observed. Concentration of organic carbon was ten times higher than that of elemental carbon, and the average OC contribution to PM 10 mass was very high (31.6%). An inverse situation was observed when air masses were transported from over the Atlantic Ocean, the North Sea and the Baltic Sea. These clean air masses were characterized by the lowest concentrations of all analysed compounds.Obtained results for organic and elemental carbon fluxes showed that atmospheric aerosols can be treated, along with water run-off, as a carbon source for the coastal waters of the Baltic Sea. The enrichment of surface water was more effective in the case of organic carbon (0.27 ± 0.19 mmol m⁻² d⁻¹). Elemental carbon fluxes were one order of magnitude smaller, on average 0.03 ± 0.04 mmol m⁻² d⁻¹. We suggest that in some situations atmospheric carbon input can explain up to 18% of total carbon fluxes into the Baltic coastal waters.     

A 7-GHz multiloop ring oscillator in 0.18-μm CMOS technology

A novel delay stage for ring oscillator utilizing multiloop technique is presented in this paper. Different conventional delay stages for the multiloop ring oscillators have been reviewed and analyzed in this work. By using push-pull inverter as the secondary input in its delay cell, the proposed oscillator demonstrates a frequency improvement of up to 17% when compared with conventional designs. The fabricated oscillator is measured to cover a frequency range of 6.24–7.04 GHz. Operating in 1.8-V power supply, the oscillator manifests itself a phase noise of ?107.7 dBc/Hz@10 MHz offset from a center frequency of 6.25 GHz. The proposed oscillator consumes a current of 40–51 mA from the 1.8-V supply and occupies an area of 440 μm ×  430 μm.