Adsorption optimization and modeling of Hg2+ ions from aqueous solutions using response surface methodology by SNPs-CS bionanocomposite produced from rice husk agro-industrial waste as a novel environmentally-friendly bionanoadsorbent

In the present research, extraction of silica (SiO2) from rice husk (RH) was optimized and silica nanoparticles (SNPs) was produced using it and functionalized by chitosan (CS) functional groups to obtain CS functionalized SNPs (SNPs-CS) bionanocomposite for the first time. The physical and chemical characteristics of the produced materials were examined using structural analyses. The results of structural analyses confirmed the fine structure of the produced materials. The SNPs-CS bionanocomposite was applied to effectively remove Hg2+ ions from aqueous solutions as an environmentally-friendly bionanoadsorbent and optimization and modeling of the adsorption conditions was explored using designed experiments by Design-Expert software with central composite design (CCD) and response surface methodology (RSM). Optimum adsorption conditions were obtained as solution pH of 6, SNPs-CS dosage of 0.1 g L-1 and Hg2+ ions concentration of 100 mg L-1 by removal efficiency of 85% and desirability function of 0.876. The results of adsorption kinetic showed a better fit of the pseudo-second-order model with experimental data, indicating the chemisorption of the adsorption process. The better fit of the Langmuir model with experimental data was confirmed by the results of adsorption isotherms, demonstrating monolayer adsorption on the homogeneous surface. The adsorption thermodynamic results illustrated the exothermicity and spontaneity of the adsorption reaction. The results of SNPs-CS recovery depicted its excellent recovery ability of removal efficiency with more than 90% after five consecutive adsorption and desorption cycles, which proved high potential of the produced bionanocomposite for industrial applications.

Binary toxicity of engineered silica nanoparticles (nSiO2) and arsenic (III) to zebrafish (Danio rerio): application of response surface methodology

Increasing production and use of engineered nanoparticles (NPs) leads to their release into the aquatic environments where they can interact with other hazardous contaminants, such as heavy metals, and threaten aquatic organisms. This study considers the ecotoxicity of arsenic (III) and silica nanoparticles (nSiO₂), individually and simultaneously, to the zebrafish (Danio rerio) using response surface methodology (RSM) under central composite design (CCD). The results revealed that in the treatments within the concentration range of 1 to 5 mg L^-1 arsenic and 1-100 mg L^-1 nSiO₂, no mortality was observed after 96 h. The optimal conditions for achieving the lowest effect of simultaneous toxicity in the concentration range of nSiO₂ and arsenic were 100 and 7 mg L^-1, respectively. Accordingly, the desirable function of the predicted model was found to be 0.78. According to these results, arsenic is toxic for zebrafish. Importantly, exposure to nSiO₂ alone did not cause acute toxicity in the studied species, while arsenic toxicity decreased by increasing the concentration of nSiO₂.

Heavy metal concentrations in Caspian pond turtle (Mauremys caspica) in Zarivar International Wetland, Kurdistan Province of Iran

In the present study, the cadmium, lead, and zinc levels in the blood and shell of Caspian pond turtles (Mauremys caspica) were investigated at five stations in Zarivar International Wetland in Kurdistan Province. All specimens were released at their capture locations within 2 h of capture. Water samples were collected at each station. Heavy metal concentrations were determined using an atomic absorption spectrometer. The mean cadmium, lead, and zinc concentrations were 0.04, 32.10, and 11.45 mg/l in blood samples; 1.82, 16.91, and 89.22 mg/l in shell samples; 0.005, 1.30, and 0.07 mg/l in water samples, respectively. In this study, the highest metal adsorption was zinc and was observed in shell. According to the results of this study, the shell of the Caspian Pond Turtle can be used to estimate the concentration of heavy metals. Our results suggest that Caspian pond turtle can be used as a biological indicator to estimate heavy metals.

In silico modeling of the antagonistic effect of mercuric chloride and silver nanoparticles on the mortality rate of zebrafish (Danio rerio) based on response surface methodology

In this study, in silico modeling was designed to examine the antagonistic effect of mercuric chloride (HgCl₂) and silver nanoparticles (AgNPs) on the mortality rate of zebrafish (Danio rerio) based on response surface methodology (RSM). Adult zebrafish (Danio rerio) with an average weight of 0.75 ± 0.16 g were used in this study. An interaction between HgCl₂ and AgNPs was evaluated using DLS, TEM, and EDX mapping. In addition, RSM was applied to determine and predict the mortality rate of zebrafish induced by HgCl₂ in the presence of non-lethal concentrations of AgNPs and to optimize dependent and independent variables. Following exposure to HgCl₂, in vitro observations showed an increase in the hydrodynamic size of AgNPs and the formation of irregular nanoparticles. EDX mapping analysis also demonstrated the deposition of Hg ions on the surface of AgNPs, indicating the interaction between HgCl₂ and AgNPs (i.e., the amalgamation of Hg and AgNPs). Moreover, in silico and in vivo findings illustrated that the mortality rate of zebrafish increased significantly in a concentration-dependent manner; however, the mortality rate reduced greatly in the presence of AgNPs during 96-h exposure. Statistically significant correlation and regression were also observed for the mortality rate between the actual and predicted values based on the ANOVA results, showing that the proposed model fits well. The most critical conditions of mortality rate were occurred by HgCl₂ concentration of 0.23 mg L^-1 and AgNP concentration of 0.04 mg L^-1 that yielding maximum fish mortality rate of 96.541%. Additionally, the obtained value for model desirability was equal to 1.000 (i.e., the highest possible value). In conclusion, this statistical model could accurately describe the relationship between independent and dependent variables, and consequently boost substantially the experimental design of ecotoxicological studies by reducing the number of model organisms, toxic and chemical substances, time, and budget.

Effects of lead ions on germination, initial growth, and physiological characteristics of Lolium perenne L. species and its bioaccumulation potential

The present study was conducted to investigate the responses of Lolium perenne L. species to lead ions. To do this, the effects of lead ions at five levels: control (blank), 250, 500, 750, and 1000 mg/kg or mg/L (depending on germination in the soil or petri dish) on the germination, initial growth, and physiological characteristics of Lolium perenne were investigated. The results showed that the difference between various lead concentrations was statistically significant at 1% confidence level in all of the germination, vegetative, and physiological characteristics. In addition, the results of translocation and stress factors indicated that there was a significant difference between the control treatment and the concentrations of 250, 500, 750, and 1000 mg/L of lead ions. Results show that the mean value of stress, which was 0.3196 in the control value, reached 0.4154 at the concentrations 1000 mg/L. Different levels of lead ions had significant effect on the estimated characteristics including germination percentage, seed vigor, germination index, chlorophyll a, chlorophyll b, carotenoids, root, and shoot. The average germination percentage in the control was 46.66%, which decreased by 5% at the highest lead concentration. In addition, the average of seed vigor, which was 34.06 in the control conditions, decreased to 0.72 at the highest lead concentration. Also, the chlorophyll a dropped from 0.5261 mg/g in the control conditions to 0.3149 mg/g. On the other hand, increase in lead ion concentration affected the physiological characteristics of Lolium perenne species. Results suggest that Lolium perenne is capable of accumulating lead and is well tolerant to lead in soil. Therefore, it is concluded that it can be used for sowing on lands which are polluted to this heavy metal (up to the concentration of 1000 mg/kg).

Colorimetric and naked eye detection of trace Hg2+ ions in the environmental water samples based on plasmonic response of sodium alginate impregnated by silver nanoparticles

Water pollution with mercury is a global concern. Therefore, establishing a rapid and accurate detection method is urgently required. Nanosensors can be a perfect alternative to instrument detection. In order to overcome low sustainability of sensors, a new composite nanosensor of sodium alginate- silver nanoparticles (SA-AgNPs) was synthesized by solvent casting method and used in colorimetric and naked eye detection of trace Hg²⁺ ions in water samples. The structural features of the produced nanosensor were characterized by instrumental techniques. The obtained results confirmed the formation of AgNPs with an average size of 13.34 nm. The colorimetric sensing of Hg²⁺ was carried out under specific conditions (pH = 6 and reaction time of 7 min) with a linear correlation obtained between the absorbance at 402 nm and different Hg²⁺ ion concentrations within the range of 0.025 μM-60 μM. The synthesized composite nanosensor of SA-AgNPs detected Hg²⁺ ions with a detection limit (LOD) of 5.29 nM. In addition, this sensor was successfully applied to detect Hg²⁺ ions in the environmental water samples with recoveries within the range of 81.58% to 114.73%. The produced nanosensor exhibited good selectivity toward Hg²⁺ ions in the presence of several competing ions.

Toxicity assessment of arsenic on common carp (Cyprinus carpio) and development of natural sorbents to reduce the bioconcentration by RSM methodology

The objective of the present study was firstly acute toxicity bioassay of arsenic on common carp (Cyprinus carpio) and then the development of natural sorbent beds (clinoptilolite and pumice) to reduce bioconcentration of arsenic in muscle tissue were considered in comparative evaluation. In this regard, the acute toxicity of arsenic on juvenile fish was assessed according to the OECD guideline (No. 203). Moreover, the efficacy of clinoptilolite and pumice as natural sorbents was assessed to reduce bioconcentration of arsenic in the fish muscle tissue during a 21 day by response surface methodology (RSM) under central composite design (CCD). The most important point of this study was to evaluate the interactions between independent variables (clinoptilolite and pumice as sorbents and arsenic as pollutant) and arsenic bioconcentration in fish muscle tissue as a dependent variable (response). In these regards, a total of 24 sets of experiments (12 sets for clinoptilolite and pumice separately) were designed by the software to achieve the best adsorption conditions. According to the arsenic toxicity test, results as estimated by Probit method, the 96 h LC₅₀ was 9.48 ± 1.01 mg/L. Analysis of variance (ANOVA) which was applied to modeling and optimization of response revealed that the predicted values were in relatively good agreement with the experimental data. Additionally, the obtained value for model desirability by clinoptilolite and pumice were 0.932 and 0.958, respectively. Overall, the obtained results indicate that both adsorbents reduced the bioconcentration of As (V) in the muscle tissue of common carp, but clinoptilolite was more effective.

Deceased Organ Donation From Pediatric Donors: Does the Literature Really Help Us? Implication for More Powerful Guidelines

BACKGROUND

Brain-dead pediatric donors have always been the focus of attention because of the higher quality, utility, and possibility of their organ donation. However, donors under the age of 5 years always necessitate making more challenging management efforts, which are not clearly implied in most parts of the guidelines.

METHODS

The data obtained from 79 brain-dead pediatric donors of the Organ Procurement Unit of Masih Daneshvari Hospital, Tehran, Iran, were assessed. The donors were divided into 2 groups, including donors under 5 years of age (group A) and those between 5 and 12 years of age (group B). Metabolic, hemodynamic, hematologic, and electrolyte status as well as the suitability for donation were compared in the study groups.

RESULTS

Of 1252 donors, 6.3% were under 12 years of age. Trauma and drug toxicity were the two primary causes of brain death in group A. In comparison, trauma and brain tumor were the leading causes of brain death in group B. The prevalence of both hyperglycemia and respiratory acidosis was significantly higher in group A (P < .05). However, severe anemia and coagulopathy were more prevalent in group B (P < .05). The high-dose inotropic administration was used for 42.4% of the donors in group A, whereas only 26% of the donors in group B needed a high dose of inotropes (P < .05). The mean quantity of organ harvested per donor was 2.1 and 2.25 in groups A and B, respectively. Furthermore, donor loss was not significantly different in both groups.

CONCLUSIONS

The occurrence of different complications in donors under the age of 5 years requires special treatment considerations that should be the center of attention in the related guidelines. Organ donation per donor indicates that donors under the age of 5 years are a valuable resource for organ procurement.

Synthesis of magMCM-41 with rice husk silica as cadmium sorbent from aqueous solutions: parameters' optimization by response surface methodology

The magnetic mesoporous silica of magMCM-41 with large surface area (695 m² g^-1) and high magnetization (10.79 emu g^-1) was synthesized using extracted amorphous silica from rice husk. The synthesized materials were applied for adsorption of Cd(II) ions from aqueous solution in batch operation systems. A highly selective adsorbent was obtained by grafting 3-aminopropyltrimethoxysilane on the pores of the magMCM-41 in which the adsorption capacity of Cd(II) ions increased from 41.8 to 86 mg g^-1, under the same conditions. A total of 20 sets of experiments were planned by the central composite design under response surface methodology. The effects of three independent variables pH, initial Cd(II) ion concentration and sorbent dosage were investigated on the adsorption capacity (q_e) and removal efficiency (R) of cadmium. The best responses for Cd(II) adsorption capacity and removal efficiency were 493.21 mg g^-1 and 60.25%, respectively, which was achieved at pH of 5.05, sorbent dosage of 0.1 g L^-1 and Cd(II) concentration of 150 mg L^-1. Additionally, the obtained value for desirability was equal to 0.807. The theoretical isotherm models were applied to describe the adsorption process that the Langmuir model provides the best correlation of the equilibrium data. The kinetics study revealed that data from the experiments fitted well to the pseudo-second-order equation than the pseudo-first-order equation. The thermodynamic parameters revealed that the adsorption process strongly depended on temperature and indicated the exothermic behavior and spontaneous nature of the adsorption.

Intra-canal calcium hydroxide removal by two rotary systems: A comparative study

Aim:

The presence of calcium hydroxide (Ca(OH)₂) in the root canal interferes with the apical root canal sealing and may result in periapical lesions in the long run. The present study was aimed to compare the efficacy of two rotary systems of Race and Mtwo in the removal of Ca (OH)₂ aqueous-based from distobuccal canals of human maxillary molars.

Materials and Methods:

A total of 44 distobuccal root canals of human maxillary molars were randomly distributed into two groups of 20 canals each and two control groups. Specimens in each group were instrumented with similar master apical rotary (MAR) and flexible files according to the manufacture's guidelines. The Ca (OH)₂ paste was placed in canals using # 20 lentulo and radiographs were taken from the two dimensions. The roots were incubated for 1 week at 37°C and 100% humidity and Ca (OH)₂ was removed from canals by MAR, afterward. Then, the roots were longitudinally split in halves by diamond disk and chisel without entering the root canals. Photos were taken from the canals’ walls by a stereomicroscope with × 10 magnification. Next, according to a defined scoring system, photos were scored by four endodontists, so that scores 1 and 2 (nonvisible remnants or scattered remnants of Ca(OH)₂) were considered as acceptable and scores 3 and 4 (distinct mass or densely-packed mass of Ca(OH)₂) were regarded as nonacceptable.

Results:

The obtained findings indicated that in coronal, middle, and apical portions of the root canal, 45, 60, and 65% of Mtwo specimens and 40, 50, and 55% of specimens prepared by the Race system acquired an acceptable score (1 and 2), respectively. Moreover, the results showed no significant difference between the two groups (P > 0.05).

Conclusions:

Both Mtwo and Race rotary systems with acceptable removal efficiency (score 1 and 2) were similarly able to remove Ca(OH)₂

Anchoring of Pd(ii) complex in functionalized MCM-41 as an efficient and recoverable novel nano catalyst in C–C, C–O and C–N coupling reactions using Ph3SnCl

Pd(ii) complex on functionalized mesoporous MCM-41 as an efficient and recoverable novel nano catalyst in C–C, C–O and C–N coupling reactions using Ph₃SnCl.

Efficacy of recruitment maneuver for improving the brain dead marginal lungs to ideal

BACKGROUND

Because of the shortage of lungs for transplantation, finding the suitable lungs in brain-dead donors is an important issue. Recruitment maneuver is a strategy aimed at re-expanding collapsed and edematous lung tissue. The aim of this study was to assess the efficacy of this maneuver on improving marginal lungs for transplantation.

METHODS

From 127 brain-dead potential donor which were evaluated for lung donation in Masih Daneshvari Organ Procurement Unit of Tehran, Iran, 31 (25%) had marginal lungs for transplantation. These donors had normal chest X ray or bilateral infiltration and had PaO2 200-300 mm Hg with FIO2 100%. The recruitment maneuver was performed and arterial blood gas was obtained before and after maneuver. The maneuver lasts for 2 hours with continuous check of O2 saturation and patient's hemodynamic during. Finally, patients with normal bronchoscopy and PaO2/FIO2 >300 mm Hg were considered good candidates for lung transplantation. The frequency (%) and mean ± SD were used for description of variables and the Wilcoxon test was used for comparison between pre- and post-maneuver PaO2 with FIO2 100%.

RESULTS

The mean ± SD of PaO2/FIO2 with 100% FIO2 of patients before and after recruitment were 239 ± 62 and 269 ± 91, respectively. Recruitment maneuver could convert 10 marginal lungs (32%) to appropriate ones (PaO2 > 300) and finally 8 lungs were transplanted.

CONCLUSIONS

Findings of this study showed that recruitment maneuver could convert inappropriate lungs to appropriate ones in one third of brain-dead patients who had marginal lung condition. So, it is recommended that this maneuver is considered in the assessment protocol of lungs for donation.

Effects of sulfur water extraction on anthocyanins properties of tepals in flower of saffron (Crocus sativus L)

A sulfur solution with different metabisulfite concentrations (100, 400, 700, 1,000 and 2,000 ppm) was used to extract anthocyanins from saffron tepals. The extraction process was compared with acidified ethanol solution at similar extraction times of 20, 40, 60, 120, and 180 min at 40 °C. The recovery of anthocyanins with sulfur solution was higher than ethanol extraction and reached to 700 mg anthocyanins/100 g, when the sulfur concentration and extraction time were 700 ppm and 60 min, respectively. HPLC analysis showed that anthocyanins extracted with sulfur solution followed by partial desulfurization and reducing sulfur content (to less than 250 ppm) had around 100 % more cyanidin 3 glucosides and 100 % less pelargonidin 3,5 glucosides in comparison with ethanol extraction. Additionally, the color of low-sulfured anthocyanins had more saturation (chroma), less lightness, and more stability than the one extracted with ethanol solution. While monomeric and polymeric anthocyanins extracted with sulfur solution had less than 1 % changes after 3 h extraction time, they had more than 12 % changes when they extracted with alcoholic solution at similar conditions. Overall, the sulfur method had a potential to extract stable anthocyanins from waste and discarded saffron tepals in aqueous solvent, and with higher quantity and quality (more attractive color) than conventional ethanol extraction method.

Investigation of qualitative and quantitative of volatile organic compounds of ambient air in the Mahshahr Petrochemical Complex in 2009

BACKGROUND

Volatile organic compounds (VOCs) are human-made chemicals widely spread in the environment and produced by petrochemical industries and petroleum refineries. The aim of this research was to evaluate the distribution of VOCs in the ambient air of Mahshahr Petrochemical Complex, Iran.

METHODS

This study was a cross-sectional research performed in 2009. We used the method numbered 1501, 1500, 2000, 1003, 1005, 1010, 2555, 1300 and 1400 of the National Institute of Occupational Safety and Health (NIOSH) for the sampling and analysis of compounds in the air. A total of 204 samples were analyzed using Gas Chromatography-Mass Spectrometry (GC-MS) and a Gas Chromatography-Flame Ionization Detector (GC-FID).

RESULTS

The mean of concentrations of the pollutants in the winter is less than in summer and a strong variation occurred among the sampling site, attributed to the change in meteorology. The results indicated high concentrations of benzene in most factories. In addition, a significant difference occurred between the concentrations of the compounds in the ambient air inside and outside the factories in both seasons (P<0.050).

CONCLUSION

It seems that the atmospheric conditions of the workplace affect the spreading of the pollutants, causing the concentration of the pollutants in the summer to be higher than in the winter. In addition, the frequent prevailing wind speed in the region plays a major role in the distribution of the pollutants from Mahshahr Petrochemical factories.

Microbial pattern of bronchoalveolar lavage in brain dead donors

BACKGROUND

We assessed bronchoalveolar lavage (BAL) cultures of brain dead donors seeking to achieve better donor management and decrease transplant complications. Determining the most common source of some postoperative infections causing morbidity and mortality among lung recipients would help to reach this goal.

MATERIALS AND METHODS

This prospective study was performed on 80 brain dead donors from August 2008 to August 2009. Donors with partial pressure of arterial O2 to the fraction of inspired O2 (PaO2/FIO2)>300 mm Hg and a normal chest x-ray underwent bronchoscopy to obtain a BAL.

FINDINGS

The mean donor age was 30±14 years and 50 (63%) were males with 21 (26%) showing a positive history for smoking and 32 (40%) with turbid tracheal secretions. Chest x-ray was abnormal in 49 (61%). Positive culture BAL results were observed among 30 (38%) patients: there were 17 (90%) bacterial and 6 (22%) fungal. Finally, 16 donors (20%) were considered suitable lung donors, allowing 10 lung transplantations.

CONCLUSION

Only 20% of donors had acceptable lungs for transplantation. The high rates of positive bacterial and fungal BAL cultures in donors suggest the need for more aggressive critical care management and antibiotic therapy which may be beneficial to prevent future infections in recipients. Further prospective studies are needed to assess the correlation between donor BAL results and posttransplant morbidity and mortality.

Causes of family refusal for organ donation

INTRODUCTION

Family refusal represents a barrier for organ donation together with other cultural and religious factors possible ignorance and clinical obstacles.

METHODS

We performed this retrospective study by phone employing our organ procurement unit database, using a list of families of potential organ donors who had refused organ donation.

RESULTS

In 2009, 146 potential organ donor families refused donation. We contacted 81 families. The main reason expressed by there families to justify the refusal to donate the deceased's organs was denial and rejection of brain-death criteria (44.4%). Other causes were believing in a miracle (13.6%); fear about organ trade and unknown organ destination (9.9%); religious beliefs (8.6%); insecutrity about the brain-death diagnosis (6.2%); unstable family mood (6.2%); unknown donor wishes about donation (4.9%); belief in body integrity after death (3.7%); and fear of objection by other family members (2.5%).

CONCLUSION

Our findings showed several reasons for family refusal for organ donation; among the main cause is poor acceptance of brain death. It seems that increasing the knowledge of people about brain death and organizing strategies to confirm brain death for families are necessary to meet the organ shortage.

Eight years of lung transplantation: experience of the National Research Institute of Tuberculosis and Lung Diseases

BACKGROUND

Lung transplantation has evolved from an experimental procedure to a viable therapeutic option in many countries. In Iran, the first single-lung transplantation was performed in the year 2000, more than 3 decades after the first successful procedure in the world, and the first double-lung transplantation was performed in the year 2006.

OBJECTIVE

To describe our 8-year experience in lung transplantation.

PATIENTS AND METHODS

During 8 years, we performed 24 lung transplantation procedures. Underlying lung diseases were pulmonary fibrosis in 16 patients (66.6%); chronic obstructive pulmonary disease in 2 (8.3%); bronchiectasis in 5, including 2 patients with cystic fibrosis (20.8%), and alveolar microlithiasis in 1 (4.16%). Data for all patients were collected and analyzed. Procedures were carried out using standardized methods. The induction suppression regimen consisted of cyclosporine and methylprednisolone. Maintenance immunosuppression drugs were cyclosporine and mycophenolate mofetil, and tapering dosage of prednisolone. Patients were followed up with physical examinations, 3 times a week, as well as and cycle ergometry 3 times a week and spirometry and laboratory tests once a week and chest radiography per needed for up to 3 months posttransplantation.

RESULTS

The longest survival time was 7.2 years, in a 60-year-old patient with idiopathic pulmonary fibrosis. Fourteen patients died, 8 as a result of hemodynamic instability and/or hemorrhage, 1 as a result of bone and fat emboli, 3 after cessation of drug and 2 of them after infection.

CONCLUSION

Although lung transplantation is a complex procedure it can be performed in developing countries such as Iran.

Organ retrieval from brain-dead patients by a single organ procurement center in Iran

INTRODUCTION

The majority of transplantations depend solely on cadaveric organs. In recent years, special focus has been directed toward brain-dead patients in Iran, but it seems that there is limited information regarding the characteristics of cadaveric organ donation in our country.

MATERIALS AND METHODS

This is a retrospective analysis of data of our Organ Procurement Unit (OPU), which is one of the most active organ procurement units in Iran. We incorporated the data on all organ donations from brain-dead patients between 2004 and 2008 into the present study. Demographic characteristics of the patients along with data regarding brain death and organ donation were extracted from already registered data on patients.

RESULTS

Among 93 brain-dead patients registered in the database of the OPU, organs were retrieved from 85% (n = 79). Out of the 14 patients from whom no organ was retrieved, the cause for this failure was death before donation in 85% (n = 12). The numbers of donated organs varied between zero and six (mean +/- standard deviation = 3.1 +/- 1.7). The most donated organs in terms of frequency and count were: right kidney (n = 68; 73.1%), left kidney (n = 67; 72%), liver (n = 63; 67.7%), heart (n = 40; 43%), pancreas (n = 5; 5.4%), and lung (n = 4; 4.3%).

DISCUSSION

The overall organ retrieval rate from brain-dead patients by this OPU was comparable to that of developed countries; however, we still believe we can improve this rate/scale.

Application of traditional cyclone with spray scrubber to remove airborne silica particles emitted from stone-crushing factories

The traditional cyclone with spray scrubber was developed for the removal of airborne silica particles from local exhaust ventilation (LEV). The objective of this research is to evaluate the efficiency of this process for removing silica particles in LEV. After designing and installing a traditional cyclone and spray scrubber, air samples were obtained at the inlet and outlet of the apparatus. The mass of each collected sample was determined gravimetrically using EPA method. The efficiency of the cyclone with spray scrubber for the removal of dust particles from the LEV system was determined to be in the range of 92-99%. There was a high correlation between the inlet concentration of dust particles and the efficiency of the apparatus. The total pressure across the system was 772.17-1120.90 Pa. It was concluded that a traditional cyclone with a spray scrubber can effectively remove a very high percentage of the incoming silica particles from an LEV. The total pressure drop across the current process is less than the pressure drop across other treatment equipment, which means that our process can effectively remove silica particles while using less electricity than other processes.

Spoligotyping of Mycobacterium tuberculosis in anthracotic bronchitis

BACKGROUND

Mycobacterium tuberculosis infection has been shown to be associated with anthracotic bronchitis. However, the typical manifestation of infection is not usually present in infected patients, which raises the question of whether a particular strain of M. tuberculosis is associated with this group of patients.

OBJECTIVE

To determine whether a particular strain of M. tuberculosis is associated with anthracotic bronchitis.

DESIGN

We assessed the predominant space oligonucleotide (spoligotype) patterns of M. tuberculosis complex isolated from patients with anthracotic bronchitis and compared the results with tuberculosis (TB) subtype patterns in Iran and other countries.

RESULTS

During a 7-month period (April--October 2006), we enrolled 87 patients (30 men and 57 women) with anthracotic bronchitis, 26% (n = 23) of whom had TB. Spoligotyping of M. tuberculosis among these 23 patients showed four distinct patterns: East-African-Indian (11, 47.8%) and Central-Asian (7, 30.4%), Haarlem I (4, 17.4%) and T-1 (1, 4.3%). When compared with spoligotype patterns of M. tuberculosis in Middle Eastern countries, including Iran, anthracotic bronchitis had similar patterns.

CONCLUSION

Our results indicate that the atypical manifestations of TB in anthracotic patients are not caused by any particular subtypes of M. tuberculosis. We conclude that anthracotic bronchitis is actually an atypical presentation of tuberculous infection with common subtypes inside the bronchial mucosa.

Application of response surface methodology for optimization of lead biosorption in an aqueous solution by Aspergillus niger

Response surface methodology was applied to optimize the removal of lead ion by Aspergillus niger in an aqueous solution. Experiments were conducted based on a rotatable central composite design (CCD) and analyzed using response surface methodology (RSM). The biosorption process was investigated as a function of three independent factors viz. initial solution pH (2.8-7.2), initial lead concentration (8-30 mg/l) and biomass dosage (1.6-6 g/l). The optimum conditions for the lead biosorption were found to be 3.44, 19.28 mg/l and 3.74 g/l, respectively, for initial solution pH, initial lead ion concentration and biomass dosage. Lead biosorption capacity on dead A. niger fungal biomass was enhanced by pretreatment using NaOH. Under these conditions, maximum biosorption capacity of the biomass for removal of lead ions was obtained to 96.21%. The desirability function was used to evaluate all the factors and response in the biosorption experiments in order to find an optimum point where the desired conditions could be obtained. The A. niger particles with clean surface and high porosity may have application as biosorbent for heavy metal removal from wastewater effluents.

Deoxynivalenol and other Fusarium toxins in wheat and rye flours on the Danish market

Information on the contamination of Danish cereals and cereal products with Fusarium toxins is limited and the last survey is from 1984/1985. In the present study, the occurrence of deoxynivalenol (DON), nivalenol (NIV), HT-2 toxin, T-2 toxin and zearalenone (ZON) was investigated in flour of common wheat, durum wheat and rye. The samples were collected from 1998 to 2001 from both mills and the retail market in Denmark. A total of 190 flour samples were analysed for DON and NIV and about 60 samples for HT-2, T-2 toxin and ZON. DON was most frequently detected with an incidence rate of 78% over all samples for all years. The contamination level varied considerably from year to year, and for wheat and rye the highest incidence and DON concentrations were found in samples from the 1998 harvest. There were regular and heavy rainfalls in Denmark during the flowering period of the crops that year, and DON was found in all samples, with mean concentrations in wheat and rye flour of 191 microg kg(-1) (n=14) and 99 microg kg(-1) (n=16), respectively. Comparison of data from each harvest year showed higher contents of DON in samples of wheat (range 20-527 microg kg(-1)) than in rye (20-257 microg kg(-1)). Contents of NIV, HT-2 toxin and ZON in samples of wheat and rye were generally low, and even in positive samples the contents were close to the detection limit of the methods. The T-2 toxin was detected in only a few of the wheat samples and in low amounts. However, the toxin was found in about 50% of the rye samples collected during 1998-2000, with a mean content of 49 microg kg(-1) (n=25). Durum wheat flour showed the highest DON contamination level, and all samples (n=33) collected during 2000 and 2001 contained DON with means and medians above 1100 microg kg(-1). Over 70% of the samples contained more than 500 microg kg(-1) DON, and the highest observed concentration was 2591 microg kg(-1). The concentration of T-2 toxin in durum wheat flour was also high with five of the 10 analysed samples containing more than 100 g kg(-1).