Troubleshooting dioxins stack emissions in an industrial waste gas incinerator

An important source of dioxins and furans at present is waste incineration, utmost formed during combustion processes and emitted to the environment without being fully captured by waste-gas treatment equipment. In this study, monitoring campaign of International Toxic Equivalents for dioxins and furans (I-TEQDF), was carried out at pharmaceutical industrial waste incinerator to find a correlation between combustion parameters and feed composition with potential emission. Principal Component Analysis (PCA) shows that high values of dioxin emission correlate with short residence time of the flue gas in the furnace as well as low oxygen concentration. These operating conditions were further investigated, using COMSOL Computational Fluid Dynamics (CFD) simulation to calculate the temperature profiles along the furnace. The results suggest that the flame temperature profile is anticipated to exhibit cold areas (cold spots), which may be used as a proxy for dioxin formation due to incomplete combustion. Additionally, the calculated congeners furan to dioxin concentration ratio, points to their formation via de novo mechanism. SEM-EDS analysis preformed on the bag filter upstream the feed following its filtration, have shown large amount of iron, which may have served as a metal catalytic source for dioxin formation. The iron origin is most likely from corrosion of the feeding pipe, drifted with the waste gas and trapped on the bag filter. The results of this study provide a better understanding of the parameters controlling dioxin formation and emission from the plant and may assist a planning of process optimization in such a plant.

Oxidation and Reduction of Polycrystalline Cerium Oxide Thin Films in Hydrogen

This study investigates the oxidation state of ceria thin films' surface and subsurface under 100 mTorr hydrogen using ambient pressure X-ray photoelectron spectroscopy. We examine the influence of the initial oxidation state and sample temperature (25-450 °C) on the interaction with hydrogen. Our findings reveal that the oxidation state during hydrogen interaction involves a complex interplay between oxidizing hydride formation, reducing thermal reduction, and reducing formation of hydroxyls followed by water desorption. In all studied conditions, the subsurface exhibits a higher degree of oxidation compared to the surface, with a more subtle difference for the reduced sample. The reduced samples are significantly hydroxylated and covered with molecular water at 25 °C. We also investigate the impact of water vapor impurities in hydrogen. We find that although 1 × 10-6 Torr water vapor oxidizes ceria, it is probably not the primary driver behind the oxidation of reduced ceria in the presence of hydrogen.

Adsorption geometry and self-assembling of chiral modifier (R)-(+)-1-(1-naphthylethylamine) on Pt(111)

A mechanistic study on interaction of a chiral modifier - (R)-(+)-1-(1-naphthylethylamine) (R-NEA) - with a single crystalline Pt(111) surface is reported. The details of the adsorption geometry of individual R-NEA molecules and their intermolecular interactions are addressed by combination of infrared reflection absorption spectroscopy (IRAS) and scanning tunneling microscopy (STM). The spectroscopic observations suggest that the molecules are tilted with respect to the underlying metal substrate with the long axis of the naphthyl ring being parallel and the short axis tilted with respect to the surface. In the medium coverage range, formation of directed 3-5 membered chains was observed by STM for the first time, which points to intermolecular bonding between individual molecules and might account for an unusual tilted adsorption geometry deduced from the IR spectra. Based on the STM images revealing the atomic structure of the Pt grid close to the R-NEA chains, we propose the adsorption configuration of NEA fitting both the IRAS and STM data. The obtained results suggest that this strong intermolecular interaction energetically stabilizes the tilted adsorption geometry of the naphthyl ring, which otherwise would be expected to lie flat on the metal to maximize the dispersive interactions. At the coverage close to saturation, R-NEA builds a self-assembled overlayer with hexagonal symmetry, exhibiting intermolecular distances larger than in the directed chains.

Expression of CD133 as a cancer stem cell marker in invasive gastric carcinoma

Introduction

Gastric cancer is considered to be the fourth most common malignancy worldwide and the second cause of cancer deaths. Regarding the cancer stem cells (CSCs) theory, they are a small group of tumor cells with unrestricted self-renewal and differentiation abilities that help tumor formation. There is an interest in the utility of CD133 as a promising marker to detect the tumor stem cell population for a variety of solid malignancies including gastric cancer. Tumors that express stem cell markers such as CD133 are found to be more aggressive tumors with poor prognosis and high liability for recurrence. This study aimed to evaluate the immunohistochemical expression of CD133 in invasive gastric carcinoma and study the relation between CD133 immunohistochemical expression and different clinicopathological parameters.

Material and methods

77 cases of gastric carcinoma were collected from the surgical pathology unit at the Gastroenterology Center, Mansoura University, Egypt. CD133 expression in tumor tissue was evaluated by immunohistochemistry.

Results

CD133 expression positively correlated with tumor metastasis and recurrence. Multivariate analysis revealed CD133 positivity to be an independent prognostic factor for tumor recurrence (P = 0.03).

Conclusion

CD133 is a good marker that can predict tumor recurrence and metastasis in gastric carcinoma. Even though, studies regarding CSCs are still in their initial stages especially those related to CD133 in gastric cancer.

Molecular beam/infrared reflection-absorption spectroscopy apparatus for probing heterogeneously catalyzed reactions on functionalized and nanostructured model surfaces

A new custom-designed ultrahigh vacuum (UHV) apparatus combining molecular beam techniques and in situ surface spectroscopy for reactivity measurements on complex nanostructured model surfaces is described. It has been specifically designed to study the mechanisms, kinetics, and dynamics of heterogeneously catalyzed reactions over well-defined model catalysts consisting of metal nanoparticles supported on thin oxide films epitaxially grown on metal single crystals. The reactivity studies can be performed in a broad pressure range starting from UHV up to the ambient pressure conditions. The UHV system includes (i) a preparation chamber providing the experimental techniques required for the preparation and structural characterization of single-crystal based model catalysts such as oxide supported metal particles or ordered oxide surfaces and (ii) the reaction chamber containing three molecular beams-two effusive and one supersonic, which are crossed at the same point on the sample surface, infrared reflection-absorption spectroscopy for the detection of surface-adsorbed species, and quadrupole mass spectrometry for gas phase analysis. The supersonic beam is generated in a pulsed supersonic expansion and can be modulated via a variable duty-cycle chopper. The effusive beams are produced by newly developed compact differentially pumped sources based on multichannel glass capillary arrays. Both effusive sources can be modulated by a vacuum-motor driven chopper and are capable of providing high flux and high purity beams. The apparatus contains an ambient pressure cell, which is connected to the preparation chamber via an in situ sample transfer system and provides an experimental possibility to study the reactivity of well-defined nanostructured model catalysts in a broad range of pressure conditions-up to ambient pressure-with the gas phase analysis based on gas chromatography. Additionally, a dedicated deposition chamber is connected to the preparation chamber, which is employed for the in situ functionalization of model surfaces with large organic molecules serving as promoters or modifiers of chemical reactions. We present a general overview of the apparatus as well as a description of the individual components and their interplay. The results of the test measurements involving the most important components are presented and discussed.

Surface-Driven Keto-Enol Tautomerization: Atomistic Insights into Enol Formation and Stabilization Mechanisms

Tautomerisation of simple carbonyl compounds to their enol counterparts on metal surfaces is envisaged to enable an easier route for hydrogenation of the C=O bond in heterogeneously catalyzed reactions. To understand the mechanisms of enol formation and stabilization over catalytically active metal surfaces, we performed a mechanistic study on keto-enol tautomerization of a monocarbonyl compound acetophenon over Pt(111) surface. By employing infrared reflection adsorption spectroscopy in combination with scanning tunneling microscopy, we found that enol can be formed by building a ketone-enol dimer, in which one molecule in the enol form is stabilized through hydrogen bonding to the carbonyl group of the second ketone molecule. Based on the investigations of the co-adsorption behavior of acetophenone and hydrogen, we conclude that keto-enol tautomerization occurs in the intramolecular process and does not involve hydrogen transfer through the surface hypothesized previously.

The Effect of Sperm Morphology and Sire Fertility on Calving Rate of Finnish Ayrshire AI Bulls

Good-quality semen is a prerequisite for successful and profitable artificial insemination (AI) of modern dairy cattle. Fertility of the bulls is evaluated with andrological examinations and semen analyses, such as morphology. However, little attention has been paid to the inheritance of bull fertility. In this study, we correlated sperm morphology, birth year and station of 695 AI bulls with calving rate (CR). Sperm morphology was clearly associated with CR underlining the usefulness of morphological examination in the assessment of fertility. The correlation between the proportion of normal spermatozoa and CR was significant (p < 0.001). No significant differences were detected between stations or birth years. We also compared the CR of 695 AI bulls with the CR of their 27 sires to study the inheritance of fertility. Sire's CR did not correlate with the CR of the sons (p = 0.218). This result indicates that at least when sires of acceptable CR are used to produce sons for use in AI the inheritance of CR is not significantly correlated.

Oxidation mechanism of porous Zr₂Fe used as a hydrogen getter

We determined the oxidation mechanism of porous ST-198, which mainly comprises Zr2Fe. Oxidation kinetics depended on temperature, oxygen partial pressure, and oxidation extent. The passivation role of oxidation in hydrogen scavenging is probably due to the development of a surface oxide, independent of oxygen concentration. Zr2Fe would be a superior hydrogen getter in oxygen-contaminated environments at high temperatures, as most oxygen will be consumed at the outer shell by mass transfer limitations, protecting the bulk of the getter for hydrogen scavenging.

3-M syndrome: a novel CUL7 mutation associated with respiratory distress and a good response to GH therapy

3-M syndrome is a rare autosomal recessive disorder caused by mutations in the CUL7, OBSL1 and CCDC8 genes. It is characterised by growth failure, dysmorphic features and skeletal abnormalities. Data in the literature show variable efficacy of GH in the treatment of short stature. We report four Emirati siblings with the condition. The index case is a 10-year-old boy with characteristic features, including prenatal and postnatal growth failure, a triangular face, a long philtrum, full lips and prominent heels. Genetic testing confirmed a novel mutation (p.val88Ala) in the CUL7 gene. The parents are healthy, first-degree cousins with nine children, of whom two died in the first year of life with respiratory failure. Both had low birth weight and growth retardation. The boy's older sibling reached an adult height of 117 cm (−6.71 SDS). She was never treated with GH. He was started on GH treatment at 7 years of age, when his height was 94 cm (−5.3 SDS). 3-M syndrome should be considered in children with short stature who have associated dysmorphism and skeletal abnormalities. The diagnosis is more likely to occur in families that have a history of consanguinity and more than one affected sibling. Death in early infancy due to respiratory failure is another clue to the diagnosis, which might have a variable phenotype within a family. Genetic testing is important for confirming the diagnosis and for genetic counselling. GH treatment might be beneficial in improving stature in affected children.

Prevalence and causes of visual impairment in diabetic patients in Tunisia, North Africa

PURPOSE

To investigate the prevalence and causes of blindness and partial sight among a population of Tunisian diabetic patients.

METHODS

A cross-sectional study of 2320 randomly identified patients with diabetes mellitus. Patient's characteristics as well as data from the last ophthalmic examination were reviewed.

RESULTS

Of all patients examined, 60.2% were females and 39.8% were males. Mean age of patients was 54.5 years. Mean duration of diabetes was 7.6 years. Diabetic retinopathy (DR) was recorded in 26.3% of patients, and was proliferative in 3.4% of patients. The prevalence of visual impairment was 22.2%, with 4.4% patients legally blind and 17.8% partially sighted. Visual impairment was significantly associated with age ≥60 years (P<0.001), duration of diabetes >10 years (P<0.001), body mass index >25 (P=0.014), hypertension (P<0.001), heart disease (P<0.001), peripheral neuropathy (P=0.03), vegetative neuropathy (P=0.002), macroalbuminuria (P<0.001), cataract (P<0.001), DR (P<0.001), diabetic macular edema (P<0.001), open angle glaucoma (P<0.001), intravitreal hemorrhage (P<0.001), rubeosis iridis (P<0.001), neovascular glaucoma (P<0.001), and tractional retinal detachment (P<0.001).

CONCLUSION

The current report is the largest study of DR in North African region. It provides a baseline data against which future progress can be assessed. Screening and treatment can greatly reduce the incidence of visual impairment due to diabetes.

Chemical composition and acaricidal properties of Deverra scoparia essential oil (Araliales: Apiaceae) and blends of its major constituents against Tetranychus urticae (Acari: Tetranychidae)

The essential oil of Deverra scoparia Coss. & Durieu was investigated for its acaricidal activity against the worldwide pest twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). The essential oil was analyzed by fast gas chromatography (GC) and GC-mass spectrometry. The activities of its individual and blended constituents were determined. Our study showed that female mortality increased with increasing D. scoparia oil concentrations, with LD50 and LD90 values at 1.79 and 3.2 mg liter(-1), respectively. A reduction in fecundity had already been observed for concentrations of 0.064, 0.08, and 0.26 mg liter(-1) D. scoparia essential oil. Ten major components, comprising 98.52% of the total weight, were identified; a-pinene was the most abundant constituent (31.95%) followed by sabinene (17.24%) and delta3-carene (16.85%). The 10 major constituents of D. scoparia oil were individually tested against T. urticae females. The most potent toxicity was found with alpha-pinene, delta3-carene, and terpinen-4-ol. The presence of all constituents together in the artificial mixture caused a significant decrease in the number of eggs laid by females, at 0.26 mg liter(-1) (11 eggs), compared with the control (50 eggs). The toxicity of blends of selected constituents indicated that the presence of all constituents was necessary to reproduce the toxicity level of the natural oil.

[Hydatid disease of the first rib treated surgically by the Roos approach]

Hydatid disease is a parasitic infection due to Echinococcus granulosus. Since involvement of the ribs and in particular the first rib is rare, diagnosis and treatment in these locations can pose special problems. The purpose of this report is to describe the case of a 27-year-old man in whom an apical left opacity was discovered by chance. Clinical examination was normal. Thoracic ultrasound demonstrated multilocular cyst in the left apical region of the thorax. Thoracic computed tomography (CT) demonstrated a hydatid cyst originating from the first rib. The patient was operated using the technique known as the Roos approach. The procedure consisted of cystectomy with resection of the first rib. The multiloculated appearance of the lesion and erosion at the first rib was consistent with hydatid cyst. The Roos approach is the technique of choice for the treatment of the first rib.