Scaling-up of microbial electrosynthesis with multiple electrodes for in situ production of hydrogen peroxide

Microbial electrosynthesis system (MES) has recently been shown to be a promising alternative way for realizing in situ and energy-saving synthesis of hydrogen peroxide (H₂O₂). Although promising, the scaling-up feasibility of such a process is rarely reported. In this study, a 20-L up-scaled two-chamber MES reactor was developed and investigated for in situ and efficient H₂O₂ electrosynthesis. Maximum H₂O₂ production rate of 10.82 mg L⁻¹ h⁻¹ and cumulative H₂O₂ concentration of 454.44 mg L⁻¹ within 42 h were obtained with an input voltage of 0.6 V, cathodic aeration velocity of 0.045 mL min⁻¹ mL⁻¹, 50 mM Na₂SO₄, and initial pH 3. The electrical energy consumption regarding direct input voltage was only 0.239 kWh kg⁻¹ H₂O₂, which was further much lower compared with laboratory-scale systems. The obtained results suggested that the future industrialization of MES technology for in situ synthesis of H₂O₂ and further application in environmental remediation have broad prospects.

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Up-scaled microbial electrosynthesis with multiple electrodes to synthesize H₂O₂

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The H₂O₂ yield was higher than that of laboratory-scale systems using graphite cathode

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Energy consumption was lower than that of laboratory-scale (bio)electrochemical systems

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Systematic evaluation of the influence of operating parameters on H₂O₂ production

A Paul trap with sectored ring electrodes for experiments with two-dimensional ion crystals

We have developed a trapped ion system for producing two-dimensional (2D) ion crystals for applications in scalable quantum computing, quantum simulations, and 2D crystal phase transition and defect studies. The trap is a modification of a Paul trap with its ring electrode flattened and split into eight identical sectors and its two endcap electrodes shaped as truncated hollow cones for laser and imaging optics access. All ten trap electrodes can be independently DC-biased to create various aspect ratio trap geometries. We trap and Doppler cool 2D crystals of up to 30 Ba⁺ ions and demonstrate the tunability of the trapping potential both in the plane of the crystal and in the transverse direction.

Global, Regional, and National Levels and Trends in Burden of Oral Conditions from 1990 to 2017: A Systematic Analysis for the Global Burden of Disease 2017 Study

Government and nongovernmental organizations need national and global estimates on the descriptive epidemiology of common oral conditions for policy planning and evaluation. The aim of this component of the Global Burden of Disease study was to produce estimates on prevalence, incidence, and years lived with disability for oral conditions from 1990 to 2017 by sex, age, and countries. In addition, this study reports the global socioeconomic pattern in burden of oral conditions by the standard World Bank classification of economies as well as the Global Burden of Disease Socio-demographic Index. The findings show that oral conditions remain a substantial population health challenge. Globally, there were 3.5 billion cases (95% uncertainty interval [95% UI], 3.2 to 3.7 billion) of oral conditions, of which 2.3 billion (95% UI, 2.1 to 2.5 billion) had untreated caries in permanent teeth, 796 million (95% UI, 671 to 930 million) had severe periodontitis, 532 million (95% UI, 443 to 622 million) had untreated caries in deciduous teeth, 267 million (95% UI, 235 to 300 million) had total tooth loss, and 139 million (95% UI, 133 to 146 million) had other oral conditions in 2017. Several patterns emerged when the World Bank’s classification of economies and the Socio-demographic Index were used as indicators of economic development. In general, more economically developed countries have the lowest burden of untreated dental caries and severe periodontitis and the highest burden of total tooth loss. The findings offer an opportunity for policy makers to identify successful oral health strategies and strengthen them; introduce and monitor different approaches where oral diseases are increasing; plan integration of oral health in the agenda for prevention of noncommunicable diseases; and estimate the cost of providing universal coverage for dental care.

Removal of Phenazopyridine from wastewater by merging biological and electrochemical methods via Azolla filiculoides and electro-Fenton process

In the present study, the potential of Azolla filiculoides (A. filiculoides) was first investigated for degradation of Phenazopyridine (PhP), an analgesic drug. The effects of main variables such as initial pharmaceutical concentration, amount of plant, and pH were studied on the efficiency of the biological process. It was observed that A. filiculoides was able to remove pharmaceuticals from contaminated water up to 85.90% during 48 h. Then, the electro-Fenton (EF) method was applied for further removal of PhP yielding a removal rate of about 98.72% under optimum conditions during 2 h. The effects of variables including the current, amount of catalyst, and pH were also studied in this phase. Also, the probability of adsorption was investigated during this step. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis were performed for the used magnetite nanoparticles, total organic carbon (TOC) were performed to investigate PhP removal efficiency during the reaction time and Gas chromatography-mass spectrometry (GC-MS) were performed to analyze degradation byproducts of PhP. Based on the results, it was found that a combination of these bioremediation and electrochemical removal steps were capable of PhP removal from contaminated water. Therefore, this approach may be effective for phytoremediation of pharmaceutical-contaminated aquatic ecosystems.

Photo-assisted electrochemical abatement of trifluralin using a cathode containing a C60-carbon nanotubes composite

This work reports the potential application of modified gas-diffusion electrode (GDE) with C₆₀-CNT composite, as a stable and efficient cathode material for degradation of trifluralin (TRL) pesticide by photo-assisted electrochemical (PE) process. C₆₀-CNT composite was prepared and characterized. Subsequently, a novel C₆₀-CNT composite modified GDE cathode was developed and the electrochemical and physical characteristics of the modified GDEs were studied. C₆₀-CNT composite/GDE showed great efficiencies for electro-generating H₂O₂, owing to huge surface area and high conductivity. Afterwards, a comparative study of TRL oxidation via photolysis, anodic oxidation (AO) and PE processes using C₆₀-CNT composite/GDE revealed the degradation percentages of 42.2, 48.5 and 93.4%, respectively, after 180 min of treatment. The TRL degradation followed a pseudo-first-order kinetics, being faster in the order: photolysis < AO < PE. The effects of various operational conditions were assessed on the degradation of TRL. From the results, PE process using C₆₀-CNT composite/GDE exhibited great performance for the degradation of TRL (20 mg L^-1) under its original pH, Na₂SO₄ electrolyte concentration of 0.05 mol L^-1, applied current intensity of 300 mA, and flow rate of 12.5 L h^-1. TOC results displayed that 92.8% of TRL was mineralized after 8 h of PE process. In addition, a plausible pathway for mineralization of TRL was proposed according to the identified by-products detected by means of gas chromatography-mass spectroscopy (GC-MS), High-performance liquid chromatography (HPLC) and ion chromatography analyses.

Kinetic modeling of sonocatalytic performance of Gd-doped CdSe nanoparticles for degradation of Acid Blue 5

CdSe and Gd-doped CdSe nanoparticles were synthesized using a simple hydrothermal method, and their catalytic activity was examined toward degradation of Acid Blue 5 (AB5) in the sonocatalytic process. The structure and morphology of as-prepared nanomaterials were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Branauer, Emmett and Teller (BET) and Fourier infrared spectroscopy (FT-IR) techniques. Among the synthesized samples, 4% Gd-doped CdSe nanoparticles demonstrated the highest catalytic activity with band gap energy of 1.61eV. The effect of dopant content, initial dye concentration, catalyst dosage, ultrasonic power and inorganic radical scavengers on the degradation efficacy of AB5 was evaluated. The produced intermediates of AB5 degradation during sonocatalytic process were verified using gas chromatography-mass spectroscopy (GC-MS) technique. A novel intrinsic kinetic model for prediction of AB5 degradation efficiency was proposed. A good agreement was obtained between developed model and experimental data (R²>0.94).

One-step preparation of nanostructured martite catalyst and graphite electrode by glow discharge plasma for heterogeneous electro-Fenton like process

Natural Martite ore particles and graphite were modified by alternating current (AC) glow discharge plasma to form nanostructured catalyst and cathode electrode for using in the heterogeneous-electro Fenton-like (Het-EF-like) process. The performance of the plasma-treated martite (PTM) and graphite electrode (PTGE) was studied for the treatment of paraquat herbicide in a batch system. 85.78% degradation efficiency for 20 mg L^-1 paraquat was achieved in the modified process under desired operational conditions (i.e. current intensity of 300 mA, catalyst amount of 1 g L^-1, pH = 6, and background electrolyte (Na₂SO₄) concentration of 0.05 mol L^-1) which was higher than the 41.03% for the unmodified one after 150 min of treatment. The ecofriendly modification of the martite particles and the graphite electrode, no chemical needed, low leached iron and milder operational pH were the main privileges of plasma utilization. Moreover, the degradation efficiency through the process was not declined after five repeated cycles at the optimized conditions, which proved the stability of the nanostructured PTM and PTGE in the long-term usage. The archived results exhibit this method is the first example of high efficient, cost-effective, and environment-friendly method for generation of nanostructured samples.

A novel and sensitive chemosensor based on a KMnO4–rhodamine B–CdS quantum dot chemiluminescence system for meropenem detection

The reaction of a KMnO₄–Rh B–l-cysteine capped CdS QD system is described as a novel chemiluminescence (CL) reaction. Meropenem exhibits a quenching effect on KMnO₄–Rh B–l-cysteine capped CdS QDs.

Flow-injection chemiluminescence analysis for sensitive determination of atenolol using cadmium sulfide quantum dots

A sensitive, rapid and simple flow-injection chemiluminescence (CL) system based on the light emitted from KMnO4-cadmium sulfide quantum dots (CdS QDs) reaction in the presence of cetyltrimethylammonium bromide (CTAB) in acidic medium was developed as a CL probe for the sensitive determination of atenolol. Optical and structural features of CdS QDs capped with l-cysteine, which synthesized via hydrothermal approach, were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL), and UV-Vis spectroscopy. The CL intensity of KMnO4-CdS QDs-CTAB was remarkably enhanced in the presence of trace level of atenolol. Under optimum experimental conditions, there is a linear relationship between the increase in CL intensity of KMnO4-CdS QDs-CTAB system and atenolol concentration in a range of 0.001 to 4.0 mg L(-1) and 4.0 to 18.0 mg L(-1), with a detection limit (3σ) of 0.0010 mg L(-1). A possible mechanism for KMnO4-CdS QDs-CTAB-atenolol CL reaction is proposed. To prove the practical application of the KMnO4-CdS QDs-CTAB CL method, the method was applied for the determination of atenolol in spiked environmental water samples and commercial pharmaceutical formulation. Furthermore, corona discharge ionization ion mobility spectrometry (CD-IMS) technique was utilized for determination of atenolol.

A flow injection chemiluminescence method for determination of nalidixic acid based on KMnO₄-morin sensitized with CdS quantum dots

A simple and sensitive flow injection chemiluminescence (CL) method was developed for determination of nalidixic acid by application of CdS quantum dots (QDs) in KMnO4-morin CL system in acidic medium. Optical and structural features of L-cysteine capped CdS quantum dots which were synthesized via hydrothermal approach were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL), and ultraviolet-visible (UV-Vis) spectroscopy. Moreover, the potential mechanism of the proposed CL method was described using the results of the kinetic curves of CL systems, the spectra of CL, PL and UV-Vis analyses. The CL intensity of the KMnO4-morin-CdS QDs system was considerably increased in the presence of nalidixic acid. Under the optimum condition, the enhanced CL intensity was linearly proportional to the concentration of nalidixic acid in the range of 0.0013 to 21.0 mg L(-1), with a detection limit of (3σ) 0.003 mg L(-1). Also, the proposed CL method was utilized for determination of nalidixic acid in environmental water samples, and commercial pharmaceutical formulation to approve its applicability. Furthermore, corona discharge ionization ion mobility spectrometry (CD-IMS) method was utilized for determination of nalidixic acid and the results of real sample analysis by two proposed methods were compared. Comparison the analytical features of these methods represented that the proposed CL method is preferable to CD-IMS method for determination of nalidixic acid due to its high sensitivity and precision.

Comparison of two methods for selegiline determination: A flow-injection chemiluminescence method using cadmium sulfide quantum dots and corona discharge ion mobility spectrometry

Two analytical approaches including chemiluminescence (CL) and corona discharge ionization ion mobility spectrometry (CD-IMS) were developed for sensitive determination of selegiline (SG). We found that the CL intensity of the KMnO4-Na2S2O3 CL system was significantly enhanced in the presence of L-cysteine capped CdS quantum dots (QDs). A possible CL mechanism for this CL reaction is proposed. In the presence of SG, the enhanced CL system was inhibited. Based on this inhibition, a simple and sensitive flow-injection CL method was proposed for the determination of SG. Under optimum experimental conditions, the decreased CL intensity was proportional to SG concentration in the range of 0.01 to 30.0 mg L(-1). The detection limit (3σ) was 0.004 mg L(-1). Also, SG was determined using CD-IMS, and under optimum conditions of CD-IMS, calibration curves were linear in the range of 0.15 to 42.0 mg L(-1), with a detection limit (3σ) of 0.03 mg L(-1). The precision of the two methods was calculated by analyzing samples containing 5.0 mg L(-1) of SG (n=11). The relative standard deviations (RSDs%) of the flow-injection CL and CD-IMS methods are 2.17% and 3.83%, respectively. The proposed CL system exhibits a higher sensitivity and precision than the CD-IMS method for the determination of SG.

A simple and sensitive flow injection method based on the catalytic activity of CdS quantum dots in an acidic permanganate chemiluminescence system for determination of formaldehyde in water and wastewater

The intensity of emitted light from KMnO₄–HCHO–CdS QDs system is linearly proportional to HCHO concentration.

Determination of dexamethasone by flow-injection chemiluminescence method using capped CdS quantum dots

L-Cysteine capped CdS quantum dots (QDs) were synthesized through a facile hydrothermal method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) and UV-Vis spectroscopy. The light emitted from KMnO4-L-cysteine capped CdS QDs reaction in acidic medium was applied as a simple and sensitive chemiluminescence (CL) system for determination of dexamethasone. The CL intensity of KMnO4-L-cysteine capped CdS QDs CL system was remarkably enhanced in the presence of dexamethasone. Under optimum experimental conditions, the enhanced CL intensity was related to dexamethasone concentration in the range of 0.004-25.0 mg L(-1), with the detection limit (3σ) of 0.0013 mg L(-1). The analytical applicability of the proposed CL system was assessed by determining dexamethasone in spiked environmental water samples and pharmaceutical formulation. The analytical performances of proposed flow-injection CL method for the determination of dexamethasone were compared with those obtained by corona discharge ionization ion mobility spectrometry (CD-IMS) method. The proposed CL system exhibits a higher sensitivity and precision than the CD-IMS method for the determination of dexamethasone.

A novel permanganate–morin–CdS quantum dots flow injection chemiluminescence system for sensitive determination of vancomycin

The intensity of emitted light from KMnO₄−morin−CdS QDs system is described as a novel chemiluminescence (CL) reaction. The CL intensity of this CL system was remarkably enhanced in the presence of vancomycin.

CuO nanosheets-enhanced flow-injection chemiluminescence system for determination of vancomycin in water, pharmaceutical and human serum

A novel, rapid and sensitive CuO nanosheets (NSs) amplified flow-injection chemiluminescence (CL) system, luminol-H2O2-CuO nanosheets, was developed for determination of the vancomycin hydrochloride for the first time. It was found that vancomycin could efficiently inhibit the CL intensity of luminol-H2O2-CuO nanosheets system in alkaline medium. Under the optimum conditions, the inhibited CL intensity was linearly proportional to the concentration of vancomycin over the ranges of 0.5-18.0 and 18.0-40.0 mg L(-1), with a detection limit (3σ) of 0.1 mg L(-1). The precision was calculated by analyzing samples containing 5.0 mg L(-1) vancomycin (n=11) and the relative standard deviation (RSD) was 2.8%. Also, a high injection throughput of 120 sample h(-1) was obtained. The CuO nanosheets were synthesized by a sonochemical method. Also, X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were employed to characterize the CuO nanosheets. The method was successfully employed to determine vancomycin hydrochloride in environmental water samples, pharmaceutical formulation and spiked human serum.

Determining nutrients degradation kinetics of chickpea (Cicer arietinum) straw using nylon bag technique in sheep

Straw a by-product from grain legume crops is produced in large quantities in Iran. Straw is constant component of ruminant diets on small holder farms; however, there is little information about its nutritive value. Accordingly experiment was conducted to determine the chemical composition and ruminal organic matter (OM) and crude protein (CP) degradability of chickpea straw using nylon bags (in situ) technique. Replicated samples were incubated at 0, 2, 4, 8, 12, 24, 48 and 72 hours in three rumen canulated Ghezel rams with 50±3 kg body weight. Dry matter (DM), CP, ether extract (EE), OM, crude fiber (CF) and nitrogen free extract (NFE) content of chickpea straws were 92.2, 6.1, 5.5, 92.0, 34.3 and 46.2%, respectively. The soluble fraction (a) of the OM and CP of chickpea straw was 17.5 and 40.8% and potential degradability (a+b) of OM and CP was 56.7 and 72.0%, respectively. Effective degradability at different passage rates (2, 5 and 8% per hours) for OM was 51.0 44.9 and 40.7% and for CP were 68.4, 64.3 and 61.3%, respectively. In conclusion, based on chemical composition and degradation characteristics, chickpea straw could have moderate nutritive value for ruminants.

Prevalence of stress among Iranian medical students: a questionnaire survey

A cross-sectional study measured the frequency of self-reported stress symptoms among a weighted random sample of medical students in Isfahan, Islamic Republic of Iran. The data were gathered using the Kessler 10-item psychological distress scale. The overall prevalence of stress among 222 students was 61.3% and there were no statistically significant differences in stress levels between students in the pre-clinical and clinical phases or different years of study. Married students had significantly lower scores than single students but there were no differences between the sexes. Students who chose to study medicine had lower stress scores than those who were influenced by family or had no choice about the subject. Students with mild to moderate stress were significantly more likely to suffer physical problems (OR = 4.42). Interventions are needed to tackle stress and improve Iranian medical students' physical and psychological well-being.

The effects of a PRECEDE-based educational program on depression, general health, and quality of life of coronary artery bypass grafting patients

BACKGROUND

Depression is commonly reported as a consequence of coronary artery bypass grafting surgery. It is the most important barrier to proper treatment of cardiac patients, causing failure in accepting the condition, decreasing the motivation in following the therapeutic recommendations, and negatively affecting the patients' function and quality of life.

OBJECTIVE(S)

The objective of this study was to investigate the effects of a PRECEDE-based educational program on depression, general health, and quality of life in coronary artery bypass grafting surgery patients.

METHODS

The experimental study included 54 post-bypass surgery patients in Isfahan Cardiovascular Research Center. The patients were randomly assigned to intervention and comparison groups (27 patients in each). The data were collected using four questionnaires (Cardiac Depression Scale, General Health Questionnaire-12, SF-36, and a PRCEDE-based questionnaire to measure predisposing, reinforcing, enabling factors, and self-help behaviors). All subjects were pre-tested. The intervention, consisting of nine educational sessions per week (60-90min each) was implemented. The patients were followed for 2 months post-intervention and post-tested at the end of the second month.

RESULTS

Following the educational intervention, the mean scores of predisposing factors, enabling factors, reinforcing factors and self-helping behaviors were significantly increased in the intervention group, compared to the comparison group (p<0.001). The mean score for depression in the comparison group (104.5±30.4) and intervention group (112.8±21.9) decreased significantly following educational intervention, but the change was more pronounced in the intervention group compared with the control group (66.2±22 vs. 89.2±27.8). The difference between the two groups on the basis of general health was statistically significant (p<0.0001). Improvements in quality of life on the basis of physical function (p<0.04), role limitations resulting from emotional status (p<0.01), and mental health (p<0.04) were statistically significant.

CONCLUSION

The findings of the study confirmed the effectiveness of an educational program based on the PRECEDE Model on decreasing depression level, improving general health, and increasing quality of life in coronary artery bypass grafting surgery patients.