Variation of Nanostructures, Molecular Interactions, and Anisotropic Elastic Moduli of Lignocellulosic Cell Walls with Moisture.

A combination of experimental, theoretical and numerical studies is used to investigate the variation of elastic moduli of lignocellulosic (bamboo) fiber cell walls with moisture content (MC). Our Nanoindentation results show that the longitudinal elastic modulus initially increased to a maximum value at about 3% MC and then decreased linearly with increasing MC. In contrast, the transverse moduli decrease linearly with MC. We showed that amorphous materials in cell walls have key roles in the variation of elastic modulus with increasing MC. Elastic modulus of lignin, calculated by molecular dynamics simulations, increases initially with increasing MC, and then decreases. In contrast, elastic modulus of hemicellulose decreases constantly with MC. Below 10% MC, water molecules tend to break hydrogen bonds between polymer chains and form new hydrogen bond bridges between the polymer chains, while above 10% MC, water molecules aggregate together and create nano-droplets inside the materials. During the process of bridging, the fractional free volume of lignin decreases. The free volume reduction along with formation of hydrogen bond bridges causes a growth in elastic modulus of lignin at low MC. The constant increase of hemicellulose free volume, however, causes the aggregation of voids in the system and diminution of elastic properties.

Survey of the relationship between metabolic syndrome and myocardial infarction in hospitals of Urmia University of medical sciences.

BACKGROUND & AIM: The aim of this study was to determine the relationship between metabolic syndrome and myocardial infarction in patients admitted to the hospitals of Urmia University of medical sciences. METHODS: A case-control study population consisted of 172 patients with heart failure who were admitted to Seyedolshohada Hospital. In this method, the researchers present in the units and along with demographic questionnaire of patients, laboratory results needed for the survey (fasting blood glucose, triglycerides and HDL) with waist circumference size, blood pressure, height and weight were examined. Data after collection were analyzed using SPSS statistical software. RESULTS: In this study of 172 patients with myocardial infarction, 56 patients (38.4%) patients were females and 112 (17.9%) were males. 1.2% of the patients were single, 84.8% were married, 0.6 were divorced and 13.5% were widowed, 116 patients (67.4%) with features of metabolic syndrome and 56 patients (32.6%) were lacking. In this study, females with myocardial infarction had more metabolic syndrome than males and in people whom relatives have a history of heart disease and also people who are overweight as well as obesity and also have features of metabolic syndrome and mean profiles of HDL, LDL, BMI, fasting blood glucose, triglyceride and waist circumference in males compared to males is higher. However, history of smoking, average number of cigarettes used per day, height and weight of males is higher than females. Other findings indicate a significant relationship between age and sex and having or not having a family history of heart failure, having or not having history of certain drugs and BMI of patient with metabolic syndrome. But a significant relationship was not found between the marital status, education, residence, income, previous history of heart disease, PCI, LDL, history of drug use, type of infarction, the extent of ejection and location with syndrome patients. In terms of survival, because none of the subjects in the study period had expired, this extent was not quantifiable. CONCLUSION: Considering the high prevalence of this disorder in Iran and that the high incidence of serious effects imposes on the health care system and that these disorders are somewhat flexible, effort towards lifestyle changes particularly healthy diets, physical activity, weight management and blood pressure, especially in women should be considered. 

Bio-inspired dental multilayers: effects of layer architecture on the contact-induced deformation.

The ceramic crown structures under occlusal contact are idealized as flat multilayered structures that are deformed under Hertzian contact loading. Those multilayers consist of a crown-like ceramic top layer, an adhesive layer and the dentin-like substrate. Bio-inspired design of the adhesive layer proposed functionally graded multilayers (FGM) that mimic the dentin-enamel junction in natural teeth. This paper examines the effects of FGM layer architecture on the contact-induced deformation of bio-inspired dental multilayers. Finite element modeling was used to explore the effects of thickness and architecture on the contact-induced stresses that are induced in bio-inspired dental multilayers. A layered nanocomposite structure was then fabricated by the sequential rolling of micro-scale nanocomposite materials with local moduli that increase from the side near the soft dentin-like polymer composite foundation to the side near the top ceramic layer. The loading rate dependence of the critical failure loads is shown to be well predicted by a slow crack growth model, which integrates the actual mechanical properties that are obtained from nanoindentation experiments.

Mechanical properties of functionally graded hierarchical bamboo structures.

This paper presents the results of a series of multi-scale experiments and numerical models concerning the mechanical properties of moso culm functionally graded bamboo structures. On the nano- and microscales, nanoindentation techniques are used to study the local variations in the Young's moduli of moso culm bamboo cross-sections. These are then incorporated into finite element models in which the actual variations in Young's moduli are used to model the deformation and fracture of bamboo during fracture toughness experiments. Similarly, the measured gradations in moduli are incorporated into crack bridging models that predict the toughening observed during resistance curve tests. The implications of the results are discussed for the bio-inspired design of structures that mimic the layered, functionally graded structure of bamboo.

Square wave voltammetric determination of methyl parathion using ZrO2-nanoparticles modified carbon paste electrode.

A carbon paste electrode is modified with ZrO(2)-nanoparticles and its application for square wave voltammetric (SWV) detection of methyl parathion, MP (organophosphate pesticide) is reported. The nano-ZrO(2) shows a strong affinity toward the phosphate group on methyl parathion molecules, which provides sensitivity and selectivity of the modified carbon paste electrode. Instrumental and chemical parameters influencing the voltammetric response are optimized for MP determination. Under optimum experimental conditions the peak current is linear to MP concentration over the range of 5.0-3000.0 ng mL(-1) with a correlation coefficient of 0.9992. The limit of detection (LOD) and limit of quantification (LOQ) for MP based on three and ten times the standard deviation of the blank (3S(b), 10S(b)) were 2.0 and 5.7 ng mL(-1) (n=20) for MP, respectively. The recovery values from quality control (QC) samples of water solutions containing low, middle and high concentrations of MP (50, 100 and 800 ng mL(-1)) were 98.0+/-2.3%, 92.5+/-4.9% and 97.6+/-2.8%, respectively. The electrode is successfully applied for the determination of MP in different water samples.

Solid phase extraction-spectrophotometric determination of fluoride in water samples using magnetic iron oxide nanoparticles.

A new, sensitive, fast and simple method using magnetic iron oxide nanoparticles (MIONs), as an adsorbent has been developed for extraction, preconcentration and determination of traces of fluoride ions. The determination method is based on the discoloration of Fe(III)-SCN complex with extracted fluoride ions which was subsequently monitored spectrophotometrically at lambda(max)=458 nm. Various parameters affecting the adsorption of fluoride by the MIONs have been investigated, such as pH of the solution, type, volume and concentration of desorbing reagent, amount of adsorbent and interference effects. A linear response for the determination of fluoride was achieved in the concentration range of 0.040-1.250 microg mL(-1). The limit of detection (LOD) and limit of quantification (LOQ) for fluoride based on 3 times and 10 times the standard deviation of the blank (3S(b), 10S(b)) were 0.015 and 0.042 microg mL(-1) (n=20) for fluoride ion, respectively. A preconcentration factor of 50 was achieved in this method. The proposed procedure has been applied for determination of fluoride concentration in various water samples. The results obtained from this method were successfully compared with those provided by standard SPADNS method.

Solid phase extraction of lead and cadmium using solid sulfur as a new metal extractor prior to determination by flame atomic absorption spectrometry.

A new method using a mini-column packed with sulfur as a new solid phase extractor has been developed for simultaneous preconcentration of lead and cadmium in water samples prior to flame atomic absorption spectrometric determinations. The effects of various parameters such as pH, flow rate of sample and eluent, type and concentration of eluent, sample volume, amount of adsorbent and interfering ions have been studied. The calibration graph was linear in the range of 10-300 and 1-20 ng mL(-1) for lead and cadmium, respectively. The limit of detection based on three times the standard deviation of the blank (3S(b)) was 3.2 and 0.2 ng mL(-1) (n=10) for lead and cadmium, respectively. A preconcentration factor of 250 was achieved in this method. The proposed procedure was applied to the determination of metal ions in tap, river and wastewater samples.

The indirect role of site distribution in high-grade dysplasia in adenomatous colorectal polyps.

BACKGROUND: The appropriate application of Endoscopic modalities for polypectomy depends on the likelihood that the adenoma in question harbors invasive cancer. While prior studies have evaluated polyp size and morphology in assessing the risk of malignancy, in recent decay some authorities have paid more attention to dysplasia. All in all, the relative risk of cancer based on polyp distribution in correlation with dysplasia has not been statistically studied which is done in our study. METHODS AND MATERIALS: Between June 2001 and March 2004, the distribution of 130 adenomatous polyps was compared with synchronous invasive or in situ cancer. Factors such as Patient age, Patients gender, location of lesion, size of polyp, histological subtype of adenoma on biopsy, degree of dysplasia, synchronous cancer, color of polyp, and number of polyps were included in the data collection. RESULTS: Multivariate logistic regression test was used to evaluate the association between malignancy and various clinical variables. It revealed histological subtype, high grade of dysplasia and size to be independent predictor of malignancy. However; left-sided location and histological subtype to be independent risk factor for high-grade dysplasia. CONCLUSION: Lesions greater than 1 cm in diameter with high-grade dysplasia after splenic flexure should be managed as presumptive malignancies with segmental colon resection. In intermediate-risk lesions the physician should decide individually.

A study on the teratogenic and cytotoxic effects of safflower extract.

In recent years, the use of carthami flos (the flowers of Carthamus tinctorius L.) as a coloring and flavoring agent has increased as a food additive in Iran. In order to evaluate its safety, the teratogenic effects of carthami flos on the central nervous system development in mice was investigated. Furthermore, its cytotoxic effect on the rat nervous cell culture was studied to complete safety evaluations. For teratogenic studies, after natural mating, pregnant mice were divided into test and control groups. The groups were treated with different dosage regimens of aqueous carthami flos extract during 0-8 days of gestation. Embryos were then isolated at the 13th gestation day and evaluated for macroscopic, microscopic and morphometric characteristics. The results showed that in higher doses (1.6 and 2 mg/kg/day) the embryos were absorbed, whereas with lower dose (1.2 mg/kg/day) changes in external, internal and longitudinal diameters, open neuropore, changes in cellular orientation and cellular degeneration were observed. The results obtained from cytotoxic assay also demonstrated a concentration-dependent cytotoxic effect of carthami flos extract. It is concluded that the use of carthami flos as a food additive should be reconsidered.

Physical, neuromotor and intellectual impairment in non-cretinous schoolchildren with iodine deficiency.

Thyroid status and neurologic, psychometric and auditory functions were evaluated in presumably normal schoolchildren aged 6 to 16 years from three areas of iodine deficiency in Iran. The subjects from each area were identified as members of groups A, B or C. In group A there were retarded growth, high prevalence of visible goiter (93%), low T4 (39%) and high TSH (70%). In group B 66% had a visible goiter and 7% had high serum TSH. In group C visible goiter was present in 22% of the subjects but they had normal thyroid function. Urinary iodine excretion was low in all three groups. Head circumference was less in groups A and B, as compared to C. Pyramidal signs occurred in over half of the subjects in Group A (hyperreflexia in 39% and crossed adductor reflex in 29%). The glabellar sign was present in 50% of group A and 20% of group B. Forty-four percent of the subjects in group A and 17% in group B had hearing deficits as shown by audiometry. Psychomotor examination was performed using the Bender Gestalt test. A higher number of errors was evident in groups A and B their psychomotor age was below their chronological age. The results of the Raven test showed mild impairment of IQ in group A, with 55% having an IQ below 91 and 15% less than 70. The subjects in group B had lower IQ than group C, but higher than group A. There was a negative correlation between serum TSH and free thyroid indices and a positive correlation between TSH and the number of pyramidal signs. This study demonstrates that mild to moderate growth retardation and neurological, auditory and psychomotor impairments occur in apparently normal subjects residing in areas of iodine deficiency.

Impairment of neuromotor and cognitive development in iodine-deficient schoolchildren with normal physical growth.

In order to detect somatic and psychomotor disturbances in children and adolescents residing in areas of iodine deficiency, schoolchildren from three areas with different degrees of iodine deficiency were studied. In Randan, the prevalence of severe endemic goiter was accompanied by alteration in thyroid function, increased thyrotropin levels and retardation of both bone and psychomotor age and decreased intellectual quotient. In Tehran, where iodine deficiency is mild, visible goiter was present in 15% of schoolchildren but no alterations in thyroid function, serum thyrotropin, somatic or psychomotor development could be detected. In Zagoon, where the prevalence and severity of goiter was less than Randan but more than Tehran, thyroid function was normal but slightly decreased as compared to Tehran; somatic development was unaltered, but retardation in psychomotor development was evident and the mean intellectual quotient was less than that of Tehranian schoolchildren. These findings indicate the occurrence of physical and psychomotor disturbances in apparently normal schoolchildren from areas of iodine deficiency. Alteration in psychomotor development may occur in children with normal physical growth, due to iodine deficiency.