Applicability of bulk and single-cell electrical impedance spectroscopy for bioprocess monitoring

The dielectric properties of biological cells serve as indicators of their physiological state. Electrical Impedance Spectroscopy (EIS) is a highly effective, non-invasive and label-free technique that can be utilized to infer information about the physiological condition of biological cells by measuring their electrical impedance across a frequency range. This technique can effectively distinguish between various types of cells and provide critical insights into their respective states, whether as individual cells or as a suspension of cells. In this thesis, the applicability of bulk and single-cell EIS for bioprocess monitoring was investigated. We developed a theoretical framework to assess the sensitivity of bulk and single-cell EIS to the cell and culture parameters of Chinese Hamster Ovary (CHO) cells (such as cell density in the culture, culture viability, cell size, and cell dielectric properties) and correlated the sensitivity analysis outcomes with the results obtained from experimental measurements. For bulk EIS measurements, we performed a comprehensive sensitivity analysis to identify the cell and culture parameters that significantly influence the permittivity spectrum measured by bulk EIS probes. For our analysis, we utilized a two-population dielectric model, including both viable and non-viable cells, to accurately represent the cell culture within a bioreactor. Additionally, we considered a double-shell dielectric model, comprising two concentric shelled spheres, to account for the nucleoplasm, nuclear envelope, cytoplasm, and plasma membrane of CHO cells. We then compared the results of our sensitivity analysis with experimental data obtained by measuring CHO cells in a lab-scale bioreactor, employing commercial bulk electrical impedance spectroscopy probes. We concluded that the most reliable cell or culture parameter that bulk EIS probes can assess is the viable cell density, through low-frequency measurements. In conventional bulk assays that rely on average properties of cell suspensions, the critical information from individual cells is lost. Consequently, researchers have increasingly turned to single-cell analysis to better understand the actual morphological and physiological properties of individual cells. By incorporating EIS measurement into microfluidic devices, highly sensitive EIS systems have been developed which are capable of single-cell analysis. Such microfluidic-based EIS systems measure the frequency-dependent complex impedance of single cells as they pass through a microfluidic channel with embedded sets of electrodes. We analyzed the sensitivity of single-cell EIS to cell dielectric properties to identify the key parameters that impact the measured impedance of an individual cell. We concluded that viable and non-viable CHO cells can be discriminated based on the phase of sensitivity of the measured impedance at frequencies above 10 MHz. This was verified with the experimental results measured from single CHO cells under starvation conditions over the frequency range from 0.3 to 30 MHz.February 202

Effective moisture diffusivity and mathematical modeling of drying compost pellet

Compost compression processes, such as pelleting, increase bulk density, improve storability, reduce transportation costs and make easier materials handling using existing equipment for handling and storage of grains. It is important to prevent quality deterioration of pellets in long time storage. Therefore, it is necessary to reduce the moisture content of the pellets to less than  or less. In this research the drying kinetics of compost pellets were studied at air temperatures of 50, 60 and 70 , air velocities of 0.5, 1 and 1.5 , particle sizes of 1.18 and 2 mm and pellet diameters of 6 and 8 mm. The maximum effective moisture diffusivity (1.78× ) was obtained at air velocity of , air temperature of 70 , particle size of 1.18 mm and pellet diameter of 8 mm. The activation energy of compost pellets varied from to  under different conditions. The Page model was selected as the most suitable model, based on the statistical analysis

Optimization compressive strength biomass pellet from compost using Taguchi method

Compression is important to prevent a deterioration in quality pellets for long term storage and the moisture content of the pellets must be reduced to or less. In this research the quality of pellet of compost was studied at air temperatures of 50, 60 and 70, air velocities of 0.5, 1, and 1.5 m/s, particle sizes of 16(1.18mm) and 10(2mm) and pellet diameters of 6 and 8 mm. The Taguchi quality engineering method was used to investigate the effects of parameters on compressive strength of pellet. An orthogonal array, signal-to-noise (S/N) ratio analysis of variance (ANOVA) were employed to analyze the effect of these compressive strength parameters. Thus, the optimal performance for the compressive strength of pellet was obtained at first level of factor A, i.e. the particle size (16 (1.18 mm)), third level of air temperature (70 ).and second level of air velocity (1 m/s). Finalliy, confirmation tests verified that the Taguchi method was successful in compressive strength of pellet

Acute phase response in experimentally infected broilers with avian infectious bronchitis virus serotype 4/91

Measurement of acute phase proteins is important for diagnosis of animal diseases. In the present study, effects of avian infectious bronchitis virus infection on acute phase response and acute phase proteins were determined. Thirty one-day-old commercial broiler chicks were reared in experimental facilities and, at the age of 21 days, were challenged intranasally with 0.2 mL of allantoic fluid virus suspension (titre 106.5 EID50 per 0.1 mL). Serum samples were obtained prior to challenge and on days 1, 2, and 5 post-inoculation. Haptoglobin, serum amyloid A and C- reactive protein concentrations were measured. Our results showed that all investigated acute phase proteins increased significantly after infection, with mean maximum concentrations between 24 h and 48 h. No correlation was observed between plasma acute phase proteins in the chickens prior and post inoculation of the virus. Haptoglobin was most sensitive factor to change in the exposed birds

Synthesis of a chitosan-based chelating resin and its application to the selective concentration and ultratrace determination of silver in environmental water samples

A novel chelating resin using chitosan as a base material, ethylenediamine-type chitosan, has been synthesized for the first time in the present study, and applied to the collection/concentration of ultratrace amounts of silver in environmental water samples. In the present study, ultratrace amounts of silver collected on the resin were eluted and determined by ICP-MS. The resin packed in a 1 mL mini column could adsorb silver selectively and quantitatively at a flow rate of 2 mL min(-1) in the wide pH range from 1 to 8, and silver adsorbed on the resin could be easily recovered by passing 1 M nitric acid as an eluent into the column. High adsorption capacity for silver at pH 5, 0.37 mmol mL(-1) of the resin, was achieved, and t(1/2) of the adsorption is less than 5 min. The effect of chloride on the collection of silver was examined by varying chloride concentrations from 10(-4) to 0.75 M; the results showed that the present resin can be used for the collection/concentration of ultratrace amounts of silver in natural waters, as well as seawater. To ensure the accuracy and the precision of the method, CASS-4 near shore seawater reference material from the NRCC has been analyzed. This is not a certified SRM for silver, but has been used for comparative silver analysis by several groups, who report very similar results to those that are reported here. The developed method using ethylenediamine-type chitosan resin gives 0.7 pg mL(-1) of the detection limit when 50-fold enrichment was used. The proposed method was successfully applied to the determination of silver in tap, river, and seawater samples

Prevalence of hepatitis G virus among hemodialysis and kidney transplant patients in Khuzestan Province, Iran

Background: Hepatitis G virus (HGV) is a member of Flaviviridae. Prevalence of HGV in healthy people is very low, but this virus is more prevalent in patients with hepatitis. Besides, relative frequency of HGV in patients undergoing hemodialysis, and kidney recipients is very high. The role of HGV in pathogenesis is not clear. Since this virus cannot be cultivated, molecular techniques such as Revers Transcription Polymerase Chain Reaction (RT-PCR) is applied to detect HGV. Objectives: The current study aimed to investigate the prevalence of HGV using determination of E2, viral envelope antigen, antibodies and the RNA by Enzyme Linked Immunosorbent Assay (ELISA) and RT-PCR techniques. The rational of the study was to determine the prevalence of HGV in patients undergoing hemodialysis and kidney transplantation in Khuzestan province, Iran. Patients and Methods: Five hundred and sixteen serum samples of the patients undergoing hemodialysis and kidney transplantation from various cities of Khuzestan province were collected. Anti-hepatitis G E2 antibodies were investigated by ELISA method. RNAs were extracted from serums and Hepatitis G RNA was detected by RT-PCR. Results: Of the 516 samples, 38 (7.36) specimens were positive for anti-HGV by ELISA. All of these ELISA positive samples were negative for HGV genome by RT-PCR. Of the remaining 478 ELISA negative samples, 16 (3.14) samples were positive by RT-PCR. Conclusions: Hepatitis G Virus was not prevalent in the patients undergoing hemodialysis and kidney transplantation in Khuzestan province. Although reports indicated high frequency of co-infection of HGV with hepatitis B and C viruses, in the current research, co-infection of HGV with B and C was not considerable. Since diferent groups and subtypes of HGV are reported, periodic epidemiologic evaluation of HGV and its co-infection with other hepatitis viruses is suggested in other populations such as the patients with thalassemia; however, periodic epidemiologic monitoring of HGV may be helpful to control future potential variations of the virus. © 2015, Ahvaz Jundishapur University of Medical Sciences