Higher Exposure Time Research Articles

Comparing Fluidized Bed Spray-Coating and Spray-Drying Encapsulation of Non-Spore-Forming Gram-Negative Bacteria

Microencapsulation of plant-beneficial bacteria for use as biopesticides is a growing area of interest in the search for alternatives to harmful chemical pesticides. In this study, we assessed the microencapsulation of the Gram-negative, non-spore-forming plant-beneficial bacterial strain Collimonas arenae Cal35 in novel cross-linked alginate microcapsules (CLAMs) formed by spray-drying, and in novel cross-linked alginate matrix shell (CLAMshell) particles formed by fluidized bed spray-coating. Survival of Cal35 was 10-fold greater in CLAMs than in CLAMshells. During individual stress tests, Cal35 was found to be more tolerant to high temperatures than to desiccation. This is consistent with the greater survival of Cal35 when encapsulated by spray-drying, which is a process that uses high inlet temperature and short exposure times to dry conditions. The particle diameter of CLAMs ranged from 5 to 20 μm, indicating potential for spray applications. CLAMshell particle diameters were between 250 and 300 μm, suggesting potential for seed coatings.

Impact of cold atmospheric plasma on microbial safety, total phenolic and flavonoid contents, antioxidant activity, volatile compounds, surface morphology, and sensory quality of green tea powder

The effects of cold atmospheric plasma (CAP) at different voltages of 20, 22, and 25 kV for 2, 4, 6, and 8 min were investigated on microbial safety, total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity (AA), volatile compounds profile, microstructure and sensory properties of green tea powder. CAP treatments effectively reduced the total microbial, mold and yeast, total coliform, Escherichia coli, and Entrococcus faecalis counts of green tea. E. coli and E. faecalis were completely deactivated in the sample exposed to plasma treatment at 25 kV for 8 min. E. coli showed higher minimum inhibitory and minimum bactericidal concentrations compared to Staphylococcus aureus. TPC, TFC and AA of green tea decreased with increases in CAP voltage and exposure time. GC–mass spectrometry identified 48 different volatile components in green tea. CAP treatment profoundly influenced the amounts of volatile compounds but the trends of changes did not follow the same pattern as the time and/or voltage of the process increased. SEM analysis showed that CAP at 20 kV for 2 or 4 min did not change the surface morphology of green tea powder while higher exposure times and voltages caused substantial ruptures in microstructure of the samples. Sensory acceptability of green tea decreased noticeably after plasma treatment at 25 kV for longer than 4 min. In conclusion, CAP treatment at 22 kV for 4 or 6 min considerably diminished microbial load of green tea powder while relatively satisfactorily preserved its TPC, TFC, AA, volatile components and sensory desirability.

Characterization and preliminary safety evaluation of nano-SiO2 isolated from instant coffee

The physiological and toxicological evaluation of nano-silicon dioxide (nano-SiO2) particles in food is important for ensuring food safety. In this study, nano-SiO2 particles isolated from five brands of instant coffee, were structurally characterized using transmission electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, dynamic light scattering, and zeta potential analyses. Their toxicity was assessed by measuring cell viability, membrane integrity, and reactive oxygen species (ROS) levels in model gastrointestinal cells (GES-1 and Caco-2). Additionally, mortality, deformity rate, heart rate and death of whole zebra fish embryos were measured. The five types of nano-SiO2 samples comprised amorphous particles with a purity of approximately 99%, which met the food additive standard. Considering that the original particle size ranged from 10 to 50 nm, the samples were classified as nano-SiO2 food additives. Nano-SiO2 did not significantly impact the activity of GES-1 or Caco-2 cells, and no significant cell membrane damage was observed (Caco-2 cells exhibited mild micro damage); however, a slight increase in intracellular RPS levels was detected. Moreover, nano-SiO2 was found to cause head deformity, pericardial edema, yolk sac edema and tail bending. Collectively, the results show that nano-SiO2 time- and dose-dependently affects GES-1 and Caco-2 cell viability, as well as the mortality, heart rate, and abnormality rate of zebra fish embryos. Specifically, a high concentration (≥ 200 μg/mL) and long exposure time (≥ 48 h) of food additive nano-SiO2 affected GES-1, Caco-2 cells, and the gastrointestinal tract in zebra fish embryos.

Covalent Conjugation of Carbon Dots with Plasmid and DNA Condensation Thereafter: Realistic Insights into the Condensate Morphology, Energetics, and Photophysics.

The use of carbon quantum dots (CDs) as trackable nanocarriers for plasmid and gene as hybrid DNA condensates has gained momentum, as evident from the significant recent research efforts. However, the in-depth morphology of the condensates, the energetics of the condensation process, and the photophysical aspects of the CD are not well understood and often disregarded. Herein, for the first time, we covalently attached linearized pUC19 with citric acid and cysteamine-derived CD through the reaction of the surface amine groups of CDs with the 5′-phospho-methyl imidazolide derivative of the plasmid to obtain a 1:1 CD-pUC19 covalent conjugate. The CD-pUC19 conjugates were further transformed into DNA condensates with spermine that displayed a toroidal morphology with a diameter of ∼200 nm involving ∼2–5 CD-pUC19 conjugates in a single condensate. While the interaction of pristine CD to spermine was exothermic, the binding of the CD-pUC19 conjugate with spermine was endothermic and primarily entropy-driven. The condensed plasmid displayed severe conformational stress and deviation from the B-form due to the compact packing of the DNA but better transfection ability than the pristine CD. The CDs in the condensates tend to come close to each other at the core that results in their shielding from excitation. However, this does not prevent them from emanating reactive oxygen species on visible light exposure that compromises the decondensation process and cell viability at higher exposure times, calling for utmost caution in establishing them as nonviral transfecting agents universally.

On improving the surface finish of 3D printing polylactic acid parts by corundum blasting

PurposeFused filament fabrication or fused deposition modeling (FFF/FDM) has as one of its main restrictions the surface quality intrinsic to the process, especially linked to the layer thickness used during manufacture. The purpose of this paper is to study the possibility of improving the surface quality of polylactic acid (PLA) parts manufactured by FFF using the shot blasting technique.Design/methodology/approachThe influence of corundum blasting on 0.2 mm layer thickness FDM PLA parts treated with two sizes of abrasive, different exposure times and different incidence pressures.FindingsAs a result, improvements of almost 80% were obtained in the surface roughness of the pieces with high exposure times, and more than 50% in just 20 s.Originality/valueThis technique is cheap, versatile and adaptable to different part sizes and geometries. Furthermore, it is a fast and environmentally friendly technique compared to conventional machining or vapor smoothing. Despite this, no previous studies have been carried out to improve the quality of this technology.

Management of oral biofilms by nisin delivery in adhesive microdevices

Numerous beneficial microbes thrive in the oral cavity where they form biofilms on dental and mucosal surfaces to get access to nutrients, and to avoid being carried away with the saliva. However, biofilm formation is also a virulence factor as it also protects pathogenic bacteria, providing them with an environment for proliferation causing oral infections. Oral hygiene relies on mechanical removal of biofilms. Some oral care products also contain antimicrobials, but effective eradication of biofilms with antimicrobials requires both a high concentration and long exposure time. In the present communication, we investigate the potential of using miniaturized drug delivery devices, known as microcontainers (MCs), to deliver the antimicrobial peptide, nisin to an oral multi-species biofilm. MCs are loaded with nisin and X-ray micro-computed tomography reveals a full release of nisin through a chitosan lid within 15 min. Chitosan-coated MCs display substantial bioadhesion to the buccal mucosa compared to non-coated MCs (68.6 ± 14.3% vs 33.8 ± 5.2%). Confocal monitoring of multi-species biofilms reveals antibacterial effects of nisin-loaded chitosan-coated MCs with a faster onset (after 3 h) compared to solution-based delivery (after 9 h). Our study shows the potential of using MCs for treatment of multi-species oral biofilms and is encouraging for further design of drug delivery devices to treat oral diseases.

Rate of coke formation of centrifugally cast austenitic chromia-forming and alumina-forming alloys in coking conditions

The coking kinetics and the long-term coking performance of an alumina-forming alloy against a traditional chromia-forming alloy was studied in a hydrogen-ethane coking atmosphere. After 1000 h of exposure, the alumina-forming alloy had 91% less mass gained compared to that of the chromia-forming alloy. Additionally, microstructural analysis showed that the carburisation attack in the chromia-forming alloy was more severe, especially at a higher temperature and at a higher exposure time. Results indicate that a better performance in coking conditions can be attained when implementing alumina-forming alloys.

Evaluation of CD8+ response in QuantiFERON-TB Gold Plus as a marker of recent infection

BackgroundDiagnosis and treatment of latent tuberculosis (TB) infection (LTBI) is essential for the elimination of TB. Preventive therapy could be limited to those with recent TB contact. QuantiFERON-TB Gold Plus (QFT-Plus), a new Interferon-γ release assay, includes a new antigen tube (TB2), which elicits CD4+ and CD8+ T-cell responses. ObjectiveThe aim of the study was to evaluate CD8+ T-cell response as a marker of recent TB infection. DesignWe retrospectively studied 1165 patients who were screened for LTBI. Patients were divided according to history of recent exposure to TB (contact with a confirmed index case in the previous year). CD8+ T-cell activity was measured as the difference between QFT-Plus tubes (TB2-TB1) using two cut-offs (>0.35 IU/mL and >0.60 IU/mL). ResultsCD8+ T-cell activity was significantly higher in the exposed group for both cut-offs (96 - 13% vs 36 - 5% patients - OR 1.68, 95% CI 1.13–2.52 for >0.35 IU/mL and 77 vs 28 patients - OR 1.72 95% CI 1.10–2.70 for >0.60 IU/mL).CD8+ T-cell activity also showed an association with positive sputum smear of the index case and higher exposure time. ConclusionCD8+ T-cell activity as measured with TB2-TB1 shows a significant association with recent exposure to TB, especially in patients with higher exposure and may prove to be a useful tool in identifying patients with recent LTBI.

Spent Grain from Malt Whisky: Assessment of the Phenolic Compounds.

In order to extract antioxidant phenolic compounds from spent grain (SG) two extraction methods were studied: the ultrasound-assisted method (US) and the Ultra-Turrax method (high stirring rate) (UT). Liquid to solid ratios, solvent concentration, time, and temperature/stirring rate were optimized. Spent grain extracts were analyzed for their total phenol content (TPC) (0.62 to 1.76 mg GAE/g SG DW for Ultra-Turrax pretreatment, and 0.57 to 2.11 mg GAE/g SG DW for ultrasound-assisted pretreatment), total flavonoid content (TFC) (0.6 to 1.67 mg QE/g SG DW for UT, and 0.5 to 1.63 mg QE/g SG DW for US), and antioxidant activity was measured using 2,2-diphenyl-2-picrylhydrazyl (DPPH) free radical (25.88% to 79.58% for UT, and 27.49% to 78.30% for UT). TPC was greater at a high stirring rate and high exposure time up to a certain extent for the Ultra-Turrax method, and at a high temperature for the ultrasound-assisted method. P-coumaric acid (20.4 ± 1.72 mg/100 SG DW for UT, and 14.0 ± 1.14 mg/100 SG DW for US) accounted for the majority of the phenolic found compounds, followed by rosmarinic (6.5 ± 0.96 mg/100 SG DW for UT, and 4.0 ± 0.76 mg/100 SG DW for US), chlorogenic (5.4 ± 1.1 mg/100 SG DW for UT, and non-detectable for US), and vanillic acids (3.1 ± 0.8 mg/100 SG DW for UT, and 10.0 ± 1.03 mg/100 SG DW for US) were found in lower quantities. Protocatechuic (0.7 ± 0.05 mg/100 SG DW for UT, and non-detectable for US), 4-hydroxy benzoic (1.1 ± 0.06 mg/100 SG DW for UT, and non-detectable for US), and caffeic acids (0.7 ± 0.03 mg/100 SG DW for UT, and non-detectable for US) were present in very small amounts. Ultrasound-assisted and Ultra-Turrax pretreatments were demonstrated to be efficient methods to recover these value-added compounds.

Generation of high dynamic range for enhancing the panorama environment

This paper presents a methodology for enhancement of panorama images environment by calculating high dynamic range. Panorama is constructing by merge of several photographs that are capturing by traditional cameras at different exposure times. Traditional cameras usually have much lower dynamic range compared to the high dynamic range in the real panorama environment, where the images are captured with traditional cameras will have regions that are too bright or too dark. A more details will be visible in bright regions with a lower exposure time and more details will be visible in dark regions with a higher exposure time. Since the details in both bright and dark regions cannot preserve in the images that are creating using traditional cameras, the proposed system have to calculate one using the images that traditional camera can actually produce. The proposed systems start by get LDR panorama image from multiple LDR images using SIFT features technology and then convert this LDR panorama image to the HDR panorama image using inverted local patterns. The results in this paper explained that the HDR panorama images that resulting from the proposed method is more realistic image and appears as it is a real panorama environment.

Nd:YAG nanosecond laser induced growth of Au nanoparticles within CMC/PVA matrix: Multifunctional nanocomposites with tunable optical and electrical properties

Gold nanoparticles (Au NPs) were successfully prepared by the Morus nigra (M. nigra) leaf extract. Polymer nanocomposite film based on host polymer matrix of carboxymethyl cellulose/polyvinyl alcohol (30/70 wt%) blend and Au NPs (0.36 wt%) had been prepared by casting of aqueous solutions. This nanocomposite film was subjected to nanosecond laser irradiation with different time intervals. The FT-IR spectra implied the miscibility of the CMC/PVA matrix through the existence of the functional groups of the virgin polymers which have been interacted by the hydrogen bond production and the intensity of these spectra was significantly increased after the Au NPs addition and irradiation process. The UV/Vis. spectra obtained the existence of gold nanoparticles in the composite film through appearance its SPR peak that had blue shift correlated by an increase in the absorbance intensity at high exposure time intervals. The TEM micrographs indicated the spherical shape of Au NPs and its size was reduced because of the addition and laser-irradiation processes. The electrical and dielectric spectra of these prepared samples were investigated. The exposure time of laser irradiation dependent electrical conductivity and dielectric permittivity was existed and the effect of interfacial polarization in these spectra was explained. The investigated properties authenticate multi-functionality of these biodegradable polymer nanocomposite samples such as optical band gap tuner and electrical conductivity and dielectric permittivity controllable nano-dielectrics for the next generation flexible electronic and optoelectronic devices.

Wavelength-dependent time–dose reciprocity and stress mechanism for UV-LED disinfection of Escherichia coli

Ultraviolet (UV) disinfection efficiency by low-pressure (LP) mercury lamp depends on the UV fluence (dose): the product of incident irradiance (fluence rate) and exposure time, with correction factors. Time–dose reciprocity may not always apply, as higher UV–LP inactivation of E. coli was obtained at a higher irradiance over shorter exposure time, for the same UV fluence. Disinfection by UV LEDs is limited by low radiant flux compared to mercury LP lamps. Our goal was to determine the UV-LED time–dose reciprocity of E. coli for four different central LED wavelengths (265, 275, 285 and 295 nm) under different fluence rates. Inactivation kinetics determined at UV-LED265 was not affected by the fluence rate or exposure time for a given UV fluence. In contrast, UV-LED275, UV-LED285, and UV-LED295 led to higher inactivation at low fluence rate coupled to high exposure time, for the same UV fluence. The intracellular damage mechanisms for each LED central wavelength were determined by using the bioreporters RecA as an indicator of bacterial DNA damage and SoxS as an indicator of oxidative stress. For 265 nm, higher DNA damage was observed, whereas for 285 and 295 nm, higher oxidative stress (possibly due to reactive oxygen species [ROS] damage) was observed. ROS inactivation of E. coli was predicted to be more effective when keeping the ROS concentration low but allowing longer exposure, for a given UV fluence.

Influence of type, concentration, exposure time, temperature, and presence of organic load on the antifungal efficacy of industrial sanitizers against Aspergillus brasiliensis (ATCC 16404)

Parameters such as type and concentration of the active compound, exposure time, application temperature, and organic load presence influence the antimicrobial action of sanitizers, although there is little data in the literature. Thus, this study aimed to evaluate the antifungal efficacy of different chemical sanitizers under different conditions according to the European Committee for Standardization (CEN). Aspergillus brasiliensis (ATCC 16404) was exposed to four compounds (benzalkonium chloride, iodine, peracetic acid, and sodium hypochlorite) at two different concentrations (minimum and maximum described on the product label), different exposure times (5, 10, and 15 min), temperatures (10, 20, 30, and 40 °C), and the presence or absence of an organic load. All parameters, including the type of sanitizer, influenced the antifungal efficacy of the tested compounds. Peracetic acid and benzalkonium chloride were the best antifungal sanitizers. The efficacy of peracetic acid increased as temperatures rose, although the opposite effect was observed for benzalkonium chloride. Sodium hypochlorite was ineffective under all tested conditions. In general, 5 min of sanitizer exposure is not enough and >10 min are necessary for effective fungal inactivation. The presence of organic load reduced sanitizer efficacy in most of the tested situations, and when comparing the efficacy of each compound in the presence and absence of an organic load, a difference of up to 1.5 log CFU was observed. The lowest concentration recommended on the sanitizer label is ineffective for 99.9% fungal inactivation, even at the highest exposure time (15 min) or under the best conditions of temperature and organic load absence. Knowledge of the influence exerted by these parameters contributes to successful hygiene since the person responsible for the sanitization process in the food facility can select and apply a certain compound in the most favorable conditions for maximum antifungal efficacy.

A preliminary study on the radiation dose reduction during catheterization procedures using simple partial patient shielding.

Reduction in X-ray exposure during cardiac catheterization is important to reduce radiation risks to operators and personnel. Reducing scattered radiation from the patient can achieve this goal. The goal of this study was to evaluate the reduction in radiation using simple partial shielding of patients undergoing cardiac catheterization. By putting a lead-based apron on the lower extremities of patients undergoing cardiac catheterization, we analyzed the reduction in total radiation dose with and without this shielding. One hundred and twelve patients were divided into two groups. In one group, the protective lead-based apron was put on the lower extremities of patients. Another group did not have any shielding. Total duration of angiography was 332 minutes and 45 seconds in the first group and 269 minutes and 10 seconds in the second group. The total radiation exposure was 33 μGy in the first group vs 606 μGy in the second group. Despite higher exposure time, total radiation dose was 22 times lower in the simple shielded group. Our simple method without any additional cost can significantly reduce radiation exposure in the cardiac catheterization laboratory.

In vitro Inactivation of SARS-Cov-2 by Povidone-Iodine In situ Gel FormingSolution

Background: Povidone Iodine (PVP-I) nasal solutions are effective against the SARS-CoV-2 virus, but are cleared rapidly from the nasal cavity, limiting its use. PVP-I gel forming solutions can circumvent this problem due to their higher viscosity and prolonged clearing time. Objective: Characterize the in vitro virucidal activity of long-acting PVP-I compositions developed using an in situ gel forming technology against the SARS-CoV-2 virus and test its safety using a rat model. Methods: We tested different dilutions of the PVP-I gel forming solution– full concentration, 90%, 50%, 28% and 9% of the original formulation concentration – at varying exposure times to assess virucidal activity against SARSCoV- 2 in VERO76 cells infected. Virucidal activity was recorded as the reduction of virus in formulation-treated test wells compared to virus controls as a log reduction value. We conducted a 28-day toxicity study using Sprague Dawley CD® IGS rats to determine the potential delayed toxicity of a PVP-I formulation. Results: The PVP-I gel-forming nasal spray rapidly inactivated SARS-CoV-2, inhibiting the viral infection of VERO76 cells. No toxicity was observed for the PVP-I formulations. Significant inactivation was noted with preincubation of the virus with this PVP-I formulation at the lowest concentrations tested. No delayed toxicity was observed in our animal model. Conclusions: PVP-I gel forming formulations inactivate SARS-CoV-2 in vitro within 30 seconds of exposure, with increasing effects seen at higher exposure times. These formulations could prove useful in a clinical setting for managing SARS-CoV-2 infected patients.

Optimization of microwave assisted multilayer drying of bittergourd

Bittergourd rings were dried to a moisture level of 0.1 g water/g dry matter using a multilayer-cummicrowave drying technique. Response surface methodology was used to optimize the drying conditions based on specific energy consumption and quality of dried bittergourd viz. change in color, rehydration ratio, shrinkage ratio, ascorbic acid content and hardness of texture. A second-order polynomial model fitted well to all responses and high R2 values (>0.8) were observed in all cases. The change in color of the dried bittergourd was found higher at high microwave power and exposure time combination, whereas 80% retention of ascorbic acid and maximum rehydration ratio was observed at 504W. The specific energy consumption decreased with an increase in microwave power due to reduced drying time. The optimum operating conditions for drying bittergourd were PL: 504W and ET:24s, resulting in dried product with maximum rehydration ratio, ascorbic acid retention, overall acceptability, minimum shrinkage ratio, hardness and color change. The overall desirability was 0.725. Use of microwave application in the last stage of drying saved 39% energy. Therefore, microwave-assisted drying should be considered for improved heat and mass transfer and produce dried bittergourd with better quality.

Гастроэзофагеальная рефлюксная болезнь у детей: аспекты клиники и диагностики с акцентом на использование внутрипищеводной рН-импедансометрии

Objective. To analyze clinical manifestations and findings of impedance pH monitoring in children with suspected gastroesophageal reflux disease (GERD). Patients and methods. This study included 237 children with clinical manifestations of GERD who underwent esophageal 24-h impedance pH monitoring, esophagogastroduodenoscopy (EGD), and barium swallow X-ray. Results. All participants with true GERD were divided into four subgroups according to their EGD results: A1 – erosive disease with high acid exposure time (AET) (29%), А2 – non-erosive disease with high AET (41%), B1 – erosive disease with a high number of reflux episodes (10%), and B2 – non-erosive disease with a high number of reflux episodes (20%). Esophageal 24-h impedance pH monitoring demonstrated that the number of reflux episodes was significantly higher in A1 group than in A2 group (р < 0.001). Esophageal symptoms prevailed in children with erosive disease (groups A1 and B1), whereas patients with nonerosive disease (groups A2 and B2) primarily presented with mixed symptoms (esophageal and extraesophageal). Conclusion. The majority of GERD patients in our sample were boys (65.1%). Non-erosive disease was more common (61%) according to EGD findings. Esophageal 24-h impedance pH monitoring demonstrated significant differences in the number of reflux episodes between the groups A1 and A2. Patients in group A1 had more frequent reflux episodes than patients in group A2 (p < 0.0001). Key words: gastroesophageal reflux disease, non-erosive reflux disease, esophageal 24-h impedance pH monitoring

A Theoretical Study of the Possibility of Obtaining the Radioisotope 13N for Medical Applications Using Dense Plasma Focus Device

The aim of this research is to study the possibility of obtaining the short-lived radioisotope 13N by colliding with a deuterium ion beam emitted by an NX2 dense plasma focus device with a graphite target, as a technique alternative to the traditional technique for getting short-lived radioisotope (SLR) accelerators. Lee code was used to study the properties of the plasma pinch, which is the source of deuterium ion beams. Then, a function of distributing the beam energy and stopping power was found within the graphite using SRIM program. The reaction cross-section was also found from an EXFOR database and the radiative yield of the reaction was calculated. The radioactivity of 13N was calculated and found to be equal to A = 4.14×103 Bq. The effect of the change in deuterium gas pressure on the radioactivity was studied and it was found that the best value for the pressure is 3 Torr, where the number of deuterium ions is the greatest amounting to 3.12×1011 ions and thus the radioactivity increased to 5.616 ×103 Bq. The effects of repetition rate of the studied dense plasma focus device and the exposure time of the graphite target to deuterium ions were studied. The radioactivity was calculated at repetition rates (1,5,10,16 ) Hz and exposure times (30,60,600) sec., where we noticed an increase in the value of radioactivity at a repetition rate of 16 Hz and an exposure time of 600 sec., reaching to 28791 × 103 Bq. To obtain a radioactivity value for 13N suitable for use in PET technique, the radioactivity value was calculated at high repetition rates (50,100,500) Hz and exposure times (30,60,600) sec. We obtained the value of radioactivity 527 ×106 Bq at a repetition rate of 500 Hz and an exposure time of 300 sec. and this value is suitable for use in PET technique. However, there are technical difficulties in the studied dense plasma focus device to obtain a high repetition rate of this value. The radioactivity of 13N was calculated at very high times of exposure of the graphite target to deuterium ions (1000, 1500, 2000, 2500, 3000) sec. at the repetition rates of the device studied. The highest radioactivity value obtained was 55.79 ×106 Bq at an exposure time of 3000 sec. and this value is less than the required value for the required use in PET technique. Keywords: Dense plasma focus device NX2, Lee code, Radioactivity.

Assessment of X-Ray Tube Technical Factors: Tube Voltage and Exposure Time in Erbil Medical Imaging Centers

Background: An evaluation of certain radiographic factors affecting patient exposure during medical imaging was carried out. Factors considered included selection of tube kilovoltage and time exposure combination. An increase in X-ray tube voltage increases the amount of radiation coming out of the X-ray tube, as well as the amount of skin dose in the image. This study aimed to assess the possibility of reducing the voltage and exposure time in medical imaging centers. The study indeed intended to protect patients from the risk of developing cancer with excessive radiation dose. Materials and Methods: This study was performed in Erbil hospitals, Iraq. NOMEX multimeter (Finland, PTW) was used to measure radiation dose (mGy), total voltage, current (mA), exposure time (s), and total filtration in 150 patients undergoing different X-ray examinations. Results: The results showed that the highest output was obtained in the age group of 42-70 years (dose range: 52.43–19.46 mGy), followed by the age group of 50-70 years (dose range: 39.9–25.63 mGy) and the age group of 10–40 years (dose range: 30.35–10.55 mGy). Conclusion: The high voltage (kVp) and high exposure time to be important factors to increase patient doses via increasing the exposure dose. Thus, optimization of exposure time and voltage is recommended for all cancer patients undergoing medical imaging with high voltage and long exposure time.

Effect of exposure time on corrosion behavior of zinc-alloy in simulated body fluid solution: Electrochemical and surface investigation

Zn alloy biocompatible implant materials have wide clinical application but its susceptibility to corrosion in the physiological environment due to increased exposure time is a major constraint. Consequently, diverse electrochemical responses have been investigated to understand the corrosion mechanism at the Zn alloy interface in different immersion times up to 168 h. A self-protective layer of Zn(OH)2 was evidenced over the surface of Zn alloy at higher exposure time in simulated body fluid (SBF) solution. The morphology and chemical composition of the zinc surface has been studied by Field emission scanning electron microscopy (FESEM), X-RAY diffraction (XRD), annulated transmission refraction (ATR), and X-RAY Photoelectron Spectroscopy (XPS). The results indicated that the Zn alloy predominantly forms zinc oxide or hydroxide and zinc phosphate compound as primary corrosion products at the interface which is confirmed from the elemental ratio (Zn/O, Zn/Cl and Zn/P 1:1, 1:2, 2:3 respectively). Additionally, FESEM results confirmed the selective formation of nano structured Zn(OH)2 which is responsible for the protectiveness of zinc specimen at higher exposure period. When Zn alloy was immersed in SBF solution, the corrosion rate was found to be 0.156–0.0976 mmy−1, which proves the sustainability of Zn alloy for biomedical applications and provides an improved degradation mechanism of Zn alloy in SBF solution.