In this work two new different sensors are developed: a pH sensor and a temperature probe. The former is based on a polyaniline (PANI) layer electrodeposited employing sinusoidal voltages and optimizing the deposition time (10-20 min). On the other hand, the temperature probe was designed taking advantage of the carbon nanotubes temperature properties. Both sensors were built on Sonogel-Carbon electrodes seeking cost effective devices. In both scenarios, results were satisfactory, the repeatability and reproducibility with values below 5%. Additionally, an excellent selectivity of the pH sensor was evaluated with the challenging interstitial matrix, prospecting an adequate future employment in real clinical samples.

A photometric flow cell for in-line determination of the biomass content in a microalgae Nannochloropsis sp. cultivation has been constructed, integrated into the photobioreactor and tested. This process is used for the development of a third-generation biofuel technology. The results obtained have shown a linear dependence of the detected optical density on the biomass content. Therefore, the concept of in-line determination of the biomass content in similar cultivation processes using a photometric sensor based on a single laser light source has been proved.

Modern microcontroller Arduino platform is often used to create electronic devices with the ability to receive signals from various digital and analog sensors, further primary processing of information with transfer to a computer, as well as to control various devices. This versatility makes it possible to create low-cost equipment for analytical and educational applications on these platforms.

As an example, this white paper describes the benefits of using Arduino microcontroller boards to create two powerful and inexpensive interfaces for computers and laboratory equipment for automating analytical chemistry laboratories. The first one is a device for carrying out coulometric titration in galvanostatic mode with potentiometric or amperometric indication of the titration end point. The instrument is used to determine the concentration of individual substances and the total antioxidant capacity of food systems. Another development is a device for determining the water activity of food systems with a capacitive sensor for determining relative humidity. Both measurement equipment uses Arduino One or Nano microcontrollers in combination with various controls for analog signal measurement, A/D conversion, and indication. The measured values are monitored in real time by transferring information to a personal computer via the USB port under the control of the developed software.

The effective use of the developed devices is presented on the example of measurements of foodstuff samples with obtaining validated data.

Hydroxocobalamin (OH-CBL) is one of the synthetic forms of water-soluble vitamin B12. This form is an efficient anti-anemic tool with a more prolonged effect than more commonly used cyanocobalamin (CN-CBL). Moreover, OH-CBL is employed as a very efficient and non-toxic antidote in case of cyanide poisoning. Many voltammetric studies have been interested in cobalamines’ voltammetric behavior concerning CN-CBL. The present study aims to examine the voltammetric behavior of OH-CBL and propose a simple and rapid method for its determination. Boron-doped diamond electrode (BDDE) was chosen as a working electrode due to its unique electrochemical properties like a wide potential window, stability, or low and stable background.

It was found that OH-CBL provided four anodic signals on BDDE in acidic supporting electrolytes of pH ≤ 3. With increasing the pH value of the supporting media, the number of signals decreased, and only one current response was recorded in the tested alkaline solutions (pH 8-11). On the other hand, one well-developed cathodic signal was observed in the whole tested pH range. The most negatively situated anodic peak was found suitable for analytical purposes due to its position and shape, which was not influenced by other signals. A supporting electrolyte based on 0.1 mol L^-1 H₂SO₄ was chosen for further experiments. A novel voltammetric approach based on differential pulse voltammetry was developed. After optimization of working parameters, it was proved that the combination of BDDE and DPV provided a sensitive analytical tool, which could be demonstrated by obtained statistical parameters, e.g., LOD = 13.2 nmol L^-1. Moreover, the proposed method was successfully applied to analyze vitamin preparations containing OH-CBL.

Citrus, a genus of flowering plants in the Rutaceae family, holds substantial market importance as a crop worldwide. After prolonged periods of breeding and extensive hybridization, numerous species have emerged, each possessing a unique metabolism that produces a diverse array of secondary metabolites. It is important to note that phenolic compounds, in particular phenols and flavonoids, are among the most important secondary metabolites in Citrus flowers. These chemical compositions of Citrus flowers differ depending on a variety of factors, such as variety, fruit maturity, environmental conditions, storage conditions, and extraction methods. Nevertheless, phenolic compounds extracted from Citrus flowers are well-recognized for their bioavailability characteristics and exhibit numerous health-promoting effects, including antioxidative, anti-inflammatory, anti-cancer and antibacterial activities in humans. The information contained in this document provides a comprehensive summary of the latest investigations conducted on the subject matter. The aim is to thoroughly comprehend the biological functions of the bioactive compounds in the Citrus flowers and their potential impacts on various biological systems, shedding light on their potential therapeutic applications.

Abstract

The human cochlea is undeniably one of the most amazing organs in the body. One of its most intriguing features is its unique capability to convert sound waves into electrical nerve impulses. Humans can generally perceive frequencies between 20 Hz and 20 kHz with their auditory systems. Several studies have been conducted on building an artificial basilar membrane for the human cochlea (cochlear biomodel). It's possible to mimic the active behavior of the basilar membrane using micro-electromechanical systems (MEMS). This paper proposes an array of MEMS bridge beams that are mechanically sensitive to the perceived audible frequency. It was designed to operate within the audible frequency range of bridge beams with 0.45 µm thickness and varying lengths between 200 µm and 2000 µm. As the materials for bridge beam structures, Molybdenum (Mo), Platinum (Pt), Chromium (Cr) and Gold (Au) have been considered. For the cochlear biomodel, platinum has proven to be the best material, closely mimicking the basilar membrane, based on the finite element (FE) and lumped element (LE) models.

Sesame (Sesamum indicum L.) is one of the oldest plants cultivated by human. Sesame has been used not only for culinary, but for cosmetic and medicinal purposes as well ^[1].

Sesame seeds are characterized by high amount of fats, which are contributing to 50% of seed mass. Additionally, sesame is a source of numerous essential amino acids, as well as lignans and tocopherols. Sesame oil, produced from roasted sesame seeds, exhibit an extraordinary antioxidant activity and is one of the most stable vegetable oils. Most of the pro-health properties are attributed to lignans, present in the sesame oil. These substances can be divided into two groups: found naturally in the oil and resulting from production of the oil. Sesamol, belonging to the second group is the compound recognized as the most important ingredient of sesame oil ^[2,3].

According to sesamol content, sesame oil exhibit many pro-health properties, such as antiinflammatory, antioxidant, antidepressive, neuroprotective or hepatoprotective, just to mention a few. Additionally, it contributes to lowering the risk of cardiovascular diseases. Sesamol content in sesame oils varies greatly – depends on oil production method, seeds origin and sesame seeds roasting conditions^[3].

This research was focused on studying the sesamol content in sesame oils, using chromatographic and voltammetric techniques. The influence of roasting temperature and roasting duration of sesame seeds on sesamol content in the oil was examined.

^[1] L.S. Hwang (et al.), Bailey’s Industrial Oil and Fat Products, 2020

^[2] Y. Wan (et al.), Society of Chemical Industry, 2005

^[3] J.M. Nzikou (et al.), Advance Journal of Food Science and Technology, 2009

The goal of the project was to monitor PM_0.1 to PM₁₀ levels in one of the four rooms in a four-bed building for a period of one month using a low-cost in accordance with the manufacturer's instructions. The data collected during this period was statistically analyzed using Minitab software. The mean PM (µg/m³) values obtained when compared with the available World Health Organisation (WHO) standards, PM_2.5 and PM₁₀ were found to be above the 24-hour limits, indicating a potential danger to the environment and individuals.

The analysis of archaeol is necessary to obtain greater knowledge about their presence in feces. This study was conducted to explore the capability of using data obtained from two spectroscopic methods, UV-Vis and FTIR and from electrochemical sensors to determine the composition of cattle feces. Principal Component Analysis and correlation analysis using the spectral data were used. By combining spectral and compositional data, useful calibrations were developed. These calibrations can be used to rapidly predict these constituents in new samples. On the basis of the results obtained here, electrochemical sensors were found successful for the rapid determination of archaeol and several other parameters in feces.

Electrochemical portable sensing systems can offer a viable solution in the analysis of environmental contaminants due to the down-size capability of the electronic components and, overall, to the simplicity of the detection principles. In the present work, a new electrochemical portable platform (EPP) with miniaturized chip-integrated gold electrodes was developed and applied for the determination of the drug acetaminophen (APAP) as a model analyte. The produced miniaturized chip-integrated gold electrodes were firstly characterized via atomic force and scanning electron microscopy, integrated in the EPP and subsequently the complete set-up was tested for electrochemical detection of APAP. The results showed adequate performance of the developed EPP when compared to a traditional electrochemical system under optimal conditions (pH 8, deposition potential 0.1 V, deposition time 240 s and scan rate of 50 mV.s^-1), with a sensitivity of 1.6 μA.mM^-1 and limit of detection of 67 µM. The EPP was validated in river and wastewater samples, achieving recoveries ranging from 93.0 to 96.6%.