Piezoelectric polymer films as power converters for human powered electronics

Piezoelectric polymer film material allows for conversion of mechanical energy into electrical energy that can be used for supplying electronic devices. While this method does not allow obtaining large useful power, recent advances in electronic technology, in particular wide availability of submicron low-power CMOS processes, have made feasible the idea of using piezoelectric polymers as power converters for human powered electronics. This concept allows to overcome the necessity of using battery as a power source, which is one of the main obstacles to widespread adoption of wearable computing devices. Of particular interest is harvesting energy from walking, which can be achieved by using piezoelectric polymers. In this paper maximum power has been calculated that can be drawn from walking energy owing to application of the copolymer polyethylene–polypropylene (PE–PP) shoe insole. The amount of electric energy obtained from a PE–PP foil of a thickness of 11 μm for a single step of a duration of 1 s – that is equivalent to a frequency of 1 Hz – amounts to 340 nJ.     

Adsorption of associating and non-associating adsorbates on microporous carbon adsorbents

The adsorption of different chemical substances on microporous carbon adsorbents has been investigated. It has been determined that the chemical character of the molecules adsorbed as well as the adsorbent texture determine the adsorption kinetics. In the case of alcohols, one of the parameters determining the sorption mechanism is the formation of complexes. As was shown earlier, the rates of complex molecule formation for methyl and ethyl alcohols differ significantly.     

Noise and optimum filtering in spectrometers with semiconductor detectors operating at elevated temperatures

This paper deals with the contribution of excess noise of a simple surface-barrier semiconductor detector to the total noise of a detector-preamplifier system when operating at elevated temperatures. Assuming a conventional CR-RC-type filter, the variance of noise output is determined. A new term “second noise-corner time constant” τ_f is proposed. The expression for relative signal-to-noise ratio as a function of the noise- (τ_c and τ_f), as well as circuit- (τ_F and τ) time constants is derived. This is also presented in a graphical form.     

Control of the electron beam active zone position in electron beam welding processes

It is known that charged particles emitted from the region of electron beam (EB) interaction with the material being processed, are an important source of information for the understanding of EB welding processes. Measurements for the three largest groups of charged particles, namely, backscattered electrons, true secondary electrons and ions are presented here. It was estimated that only the signals of the direct component amplitude of these particles’ currents, processed by neural networks, could be used to effectively control the EB welding process. Computer simulations of various models of neural networks are described. The best result was obtained for a network that determines an optimal value of focusing current for the weld being made, based on the amplitude of signals measured with a moderately defocused EB.     

Effect of metal ions on the molecular weight distribution of humic substances derived from municipal compost: ultrafiltration and size exclusion chromatography with spectrophotometric and inductively coupled plasma-MS detection

The effect of metal ions (Co, Cu, Ni, Pb, Zn) on the molecular weight distribution of humic substances (HSs) obtained from compost is studied. We believe this is the first of this type of study applied in this way to humic substances. Size exclusion chromatography is coupled with two on-line detection systems (spectrophotometric and ICPMS) to study the binding of metal ions by humic substances leached from compost. ICPMS provided highly specific, sensitive, and multielement analytical information that enabled obtaining direct experimental evidence for the participation of metal ions in molecular size distributions of humic compounds. The compost extract or its high molecular weight fraction (>5,000) was put in contact with EDTA or citrate ions, thereby competing with HSs for binding metals. The experiments were carried out by varying the pH maintained by Tris-HCl or CAPS buffer (pH 8.0 and 10.3) and keeping the ionic strength constant. The elution profile of humic substances using UV/ visible detection was compared with those from ICPMS detection of Co, Cu, Ni, Pb, and Zn in the same chromatographic runs. The results obtained suggested that both bridging between small molecules and complexation/ chelation by individual molecules are involved in metal ion binding to humic substances. The use of ICPMS to study the role of metal ions in aggregation/disassociation of humic substances proposed in this work is promising. Coupling element-specific detection with SEC or other separation systems allows better understanding of the mobility and bioaccessibility of elemental species in the environment and further elucidation of the dissolved humic structure.     

The Architecture of Curved Shapes

In the 20th century, architecture remains the part of art where formal principles are very important for creators and spectators. Because form in architecture is so important, two questions arise: How can architects nowadays create forms? How can forms be described and classified? When we work only with formal analysis, we can point to an important criterion of innovation, that is, that certain forms have never before been seen in the history of architecture. In the present day, CAD/CAM technology permits us to realize any form our imaginations can create.     

Integral bread development with soybean, chia, linseed, and folic acid as a functional food for women

Six bread formulations were developed, using different proportions of whole-wheat flour, chia seeds and flaxseed flour. All of our formulations were added with folic acid. Sensorial and texture evaluations were performed, showing good acceptance of the products. Proximal chemical analysis was carried out; in addition, the following parameters were determined: calcium, phosphorus, total dietary fiber, folic acid, water hydration capacity, Glucose Dialysis Retardation Index (GDRI) and fatty acids. The results obtained showed higher protein levels in the developed breads (23.23-30.24 (g/100g dry matter) as compared to a control (21.00% of proteins in bread elaborated without chia or flaxseed). Furthermore, the breads contained 10.07-12.15 of lipids (g/100g dry matter) (linoleic acid: 2.43-4.05%; linolenic acid: 1.12-4.46 %; oleic acid: 2.93-6.13 %), GDRI values were between 89.1 and 98.1 % and folic acid was in the range 699.44 - 991.3 (microg/100g dry matter). The same parameters were determined in the chia seed and in the flaxseed flour. It was concluded that; due to their high levels of protein, insaturated fatty acids (omega-3 and omega-6), dietary fiber and folic acid, these breads have a high nutritional value, so they could have special benefits for woman.     

Determination of Small Phenolic Compounds in Tequila by Liquid Chromatography with Ion Trap Mass Spectrometry Detection

Tequila is elaborated from Agave tequilana Weber blue variety and it is commercialized at different stages of aging. Chemical composition of this product has often been addressed; however, data on phenolic compounds are scarce. In this work, a high-performance liquid chromatography–electrospray ionization-ion trap mass spectrometry (HPLC–ESI-ITMS) procedure has been established for the determination of 34 small phenolic compounds. The combination of suitable separation conditions with extraction of chromatograms at individual m/z values has enabled for total analysis run of 17 min (11 min separation plus 6 min column cleaning/equilibration) with the detection limits in the range 1.28–75.0 μg l^?1 (0.07–6.1 pmol on-column). Commercial tequilas analyzed included 6 white, 12 rested, and 4 aged. The following acids were found and quantified: gallic, procatechuic, 4-hydroxybenzoic, vanillic, syringic, homovanillic, 3-hydroxybenzoic, ferulic, salicylic, and benzoic. The white tequilas contained fewer compounds and lower total phenolics concentrations (range 36–408 μg l^?1) as compared to the rested and aged liquors (515–4,296 and 2,048–3,249 μg l^?1, respectively). In the latter products, syringic, vanillic, procatechuic, and gallic acids were the most abundant, which indicates that maturation in wooden barrels is the main source of small phenolics in tequila. On the other part, homovanillic acid was found in all tequila types (medians for white, rested, and aged products 82, 153, and 162 μg l^?1, respectively), suggesting that some phenolics may originate from the raw material or might be formed during liquor elaboration.     

Synthesis and characterization of ceramic - polymer composites containing bioactive synthetic hydroxyapatite for biomedical applications

Presented research involved preparation of hydroxyapatite and synthesis of composites based on gelatin, albumin and polyvinylpyrrolidone (PVP) modified with the obtained compound. Hydroxyapatite was attained as a product of two-stage processing of pig bones. Applied procedure involved hydrolysis of the raw material in acidic environment and double calcination. Molar ratio Ca/P of hydroxyapatite has been determined and its chemical structure has been characterized using X-ray diffraction and FT-IR spectroscopy. Ratio Ca/P calculated on the basis of conducted research was 1.50?±?0.05. Thus prepared material met the ISO requirements, which assume that the Ca/P ratio should be in the range 1.5–2.0, which qualifies the material for further studies. Next, series of polymer matrix on the basis of gelatin, albumin and polyvinylpyrrolidone (PVP) has been synthesized and subjected to some analyzes. On the basis of the conducted studies, matrixes with the most favorable features such as desirable strength, flexibility and crosslinking degree were modified with previously prepared hydroxyapatite. Surface morphology and elemental composition of the composites have been analyzed using SEM-EDS method. Additionally, sorption capacity of modified composites and their behavior in simulated body fluids have been determined. Based on the conducted research it can be concluded that pig bones represent a good material for preparation of hydroxyapatite. Furthermore, composites based on proteins of natural origin modified with attained hydroxyapatite constitute a promising material that can be used for biomedical purposes.