Corrosion-Resistive ZrO2 Barrier Films on Selected Zn-Based Alloys

This work presents the enhanced corrosion resistance of newly developed two-layer composite coatings deposited on low-carbon steel: electrodeposited zinc alloy coatings (Zn-Ni with 10 wt.% Ni (ZN) or Zn-Co with 3 wt.% Co (ZC), respectively) and a top ZrO2 sol-gel layer. Surface morphology peculiarities and anti-corrosion characteristics were examined using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), atomic force microscopy (AFM), water contact angle (WCA) measurements, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) analyses, potentiodynamic polarization (PDP) curves, corrosion potential (Ecorr), polarization resistance (Rp) measurements (for a prolonged period of 25 days) and open-circuit potential (OCP). The results were compared with the corrosion peculiarities of usual zinc coating. The zirconia top coatings in both systems were amorphous and dense, possessing hydrophobic nature. The experimental data revealed an increased corrosion resistance and protective ability of the ZC system in comparison to that of ZN due to its smooth, homogeneous surface and the presence of poorly crystallized oxides (ZnO and Co3O4), both later playing the role of a barrier for corrosive agents.

Contact Angle and AFM Analysis of Glassy Carbon Coatings after an Extended Stay on the International Space Station (ISS)

The proposed work presents the results for contact angle and atomic force microscopy (AFM), which are applied to characterize the surface of two types of samples, “reference” sample and “space” sample, both made of the same material – graphite covered with glassy carbon coating, but stored for 28 months in different environments (conditions). One “space” sample was mounted outside the International Space Station, and the other “reference” sample was stored on Earth. The technique applied to measure the contact angle of wetting of the surface of the samples (hydrophilicity-hydrophobicity) is using water droplets. Values of the energy surface area of the sample surfaces were determined by measuring the contact angle with the substances formamide and diiodomethane. Atomic force microscopy (AFM) was applied to characterize the glass surface morphology of carbon coatings.

Atomic force microscopy study on the effect of different irrigation regimens on the surface roughness of human root canal dentin

Background

Endodontic irrigants could alter the mechanical properties of root canal dentin, such as its roughness.

Aim

To compare the effect of various irrigation protocols on root canal dentin roughness with respect to their application time, concentration, and additional ultrasonic activation.

Materials and Methods

Forty single-rooted, non-endodontically treated upper incisors were decoronated and further sectioned longitudinally in a buccolingual direction. The surfaces of all eighty samples were polished and randomly segregated to eight equal groups (n = 10): Group A: 2% NaOCl/2 min followed by 17% EDTA/2 min; Group B: 2% NaOCl/5 min followed by 17% EDTA/5 min; Group C: 5.25% NaOCl/2 min followed by 17% EDTA/2 min; Group D: 5.25% NaOCl/5 min followed by 17% EDTA/5 min; Group E: 2% NaOCl solution, ultrasonically activated for 2 min; Group F: 5.25% NaOCl, ultrasonically activated for 2 min; Group G: 2% NaOCl/2 min followed by 17% EDTA/2 min, both ultrasonically activated; Group H: Control group (distilled water).

Results

All irrigation regimens increased root dentin surface roughness in comparison with the control group. The analysis of the values revealed significant differences between the arithmetical average roughness values (Ra) in the groups (p < 0.001). A statistically significant increase in the Ra parameter was observed in groups E, F, G, and D. The irrigation protocol in Group A showed a significantly smoother dentin surface than those with the ultrasonic activation.

Conclusion

All tested irrigants increased root canal dentin roughness and the effect was time and concentration-dependent. The ultrasonic activation of the disinfection solutions roughened the root dentin surface significantly.

Prevalence of thyroid dysfunction and autoimmunity in pregnant women with gestational diabetes and diabetes type 1

OBJECTIVE

The aim of the present study was to determine the prevalence of abnormal thyroid function and antithyroid antibodies during pregnancy in women with diabetes type 1 and gestational diabetes mellitus (GDM).

METHODS

The study group included 83 pregnant women who attended the Outpatient Department of the Endocrinology, Diabetes and Metabolic Disorders Clinic in the period from 05.2009 to 11.2009. The one hundred-g. oral glucose tolerance test (OGTT) was conducted on the pregnant women except for women with diabetes type 1. Thyroid functions were evaluated in all the pregnant women. After routine screening for GDM, thirty of the pregnant women were healthy and GDM was diagnosed in forty of them. The rest, thirteen women, had diabetes type 1.

RESULTS

The women who developed GDM showed a mean free thyroxin concentration (fT4) significantly lower than that observed in the healthy pregnant women and women with diabetes type 1. Among the pregnant women with GDM, 10 women or 25% had fT4 concentrations below the lower cut-off with normal thyroid-stimulating hormone concentrations (TSH). A statistically significant difference was found in the prevalence of antithyroid antibodies (anti-TPO) between the (30%) women with diabetes type 1 and (10%) healthy pregnant women (p<0.05). In the women positive for anti-TPO, TSH was significantly higher (p<0.05).

CONCLUSION

The significantly higher prevalence of hypothyroxinemia in GDM pregnancies and anti-TPO titres in pregnancies with diabetes type 1, than in healthy pregnant women warrants routine screening for thyroid abnormalities in these groups of pregnant women.

Association between foetal growth and different maternal metabolic characteristics in women with gestational diabetes mellitus

OBJECTIVE

The aim of the study was to investigate the association between foetal growth and different maternal metabolic characteristics in women with gestational diabetes mellitus (GDM).

METHODS

The study group included 200 consecutive pregnant women who attended the Endocrinology, Diabetes and Metabolic Disorders Outpatient Department in the period from 02.2006 to 02.2009 with singleton pregnancy and GDM diagnosed following ADA criteria. The following parameters were studied: pre-pregnancy maternal body mass index (BMI), 3-hours 100g oral glucose tolerance test (OGTT) results, glycosylated haemoglobin (HbA1c), total lipids (TL), total cholesterol (TH), triglycerides (TG), HDL- and LDL-cholesterol levels at admission. Neonatal birth weight and the prevalence of being large for gestational age (LGA) was an end-point.

RESULTS

We found a significant association between birth weight and pre-pregnancy BMI, HDL-C and birth weight of a large child born previously. Birth weight of a large child born previously was the strongest independent predictor for LGA. The prevalence of LGA (from 27% to 80%) was related to a number of altered maternal characteristics.

CONCLUSION

Pre-pregnancy BMI, HDL-C and birth weight of a large child born previously are the independent predictors for LGA, but results of glucose levels during OGTT are not useful in the prediction of LGA in GDM pregnancies. Probably more factors and other maternal metabolic parameters than glucose levels during OGTT are responsible for the risk of LGA.

Gestational Diabetes Mellitus - the impact of maternal body mass index and glycaemic control on baby's birth weight

OBJECTIVES

To asses the influence of the maternal BMI and glycaemic control in women with GDM on the baby's birth weight (BW).

MATERIAL AND METHODS

We analysed 180 women with GDM. Macrosomia has been defined as BW > 4000 gm, small for gestational age < 2700 gm and appropriate for gestational age between both. According to the baby s BW the pregnant women were divided into three groups: group 1 (G1) with BW < 2700 gm (n = 26); group 2 (G2) with BW between 2700 to 4000 gm (n = 117), and group 3 (G3) with BW > 4000 gm (n = 37). We also analysed BMI (kg/m2), HbA1c (%), PPG (mmol/L) and time of delivery (WG).

RESULTS

Comparisons between G1 and G2 showed: BMI (30.7 +/- 5 & 31 +/- 5.2; p < 0.7), HbA1c (6.4 +/- 0.8 & 5.1 +/- 0.8, p < 0.002), PPG (8.2 +/- 1.7 & 6.9 +/- 1.5, p < 0.02), time of delivery (35.2 +/- 3.8 & 38.6 +/- 1.5, p < 0.0001) and BW (2289 +/- 504 & 3474 +/- 334, p < 0.0001). Comparisons between G2 and G3 showed: BMI (31 +/- 5. 2 & 33.4 +/- 6.1; p < 0.02), HbA1c (5.2 +/- 1.1 & 6.4 +/- 2.3, p < 0.02), PPG (6.9 +/- 1.5 & 8.2 +/- 1.9, p < 0.02), time of delivery (38.6 +/- 1.5 & 39.3 +/- 1.4, p < 0.01) and BW (3474 +/- 334 & 4431 +/- 302, p < 0.0001). Comparisons between G1 and G3 showed the difference at delivery time and the baby's BW (p < 0.0001).

CONCLUSIONS

Maternal obesity and PPG contribute to macrosomia and also PPG to SGE.

Metformin improves menstrual patterns, endocrine and metabolic profile in obese hyperinsulinemic women with a polycystic ovary syndrome

OBJECTIVE

To evaluate the therapeutic effect of metformin on the clinical features, hormonal and metabolic profile in obese women with a hyperinsulinemic polycystic ovary syndrome (PCOS).

MATERIAL AND METHODS

We analyzed 25 women with PCOS, mean age 27.28+/-7.85 years, BMI 34.42+/-6.61 kg/m2, FerrimanGallwey (F/G) score 17.43+/-5.45 and duration of menstrual cycle 79.2 +/- 54.5 days. Basal hormone measurements included: FSH, LH, total testosterone, DHEAS, 17 alpha OHP and E2. All patients underwent a 75 g oral glucose tolerance test (OGTT), during which fasting and stimulated levels of glucose and insulin were measured at 0', 60' and 120'. The lipid profile was also performed. Both basal and stimulated parameters were analyzed before and after treatment with metformin (500 mg orally, three times daily for 9 months).

RESULTS

After metformin treatment the mean frequency of menses became significantly more regular (79.2+/-54.5 days vs. 31.61 +/-7.7 days, P<0.01) and mean testosterone level had significantly decreased (2.78+/-1.23 vs. 1.72+/-0.95 ng/ml, (P<0.01). We also observed a statistically significant decrease in the metabolic parameters, both basal insulinemia (22.18 +/- 5.76 vs. 17.19+/-6.67 microU/ml, P<0.01), stimulated insulinemia after 60' (179.18+/-88.96 vs. 136.38+/-75.43 microU/ml, P=0.04), stimulated insulinemia after 120' (163.23 +/-89.2 vs. 88.46 +/- 61.5 U/ml, P<0.01) and glucose response to OGTT on 120' (7.07 +/- 1.82 vs. 6.15 +/-1.52 mmol/L, P=0.04). The levels of HDL cholesterol had increased (0.94+/-0.16 vs. 1.13+/-0.19 mmol/L, P=0.04). No changes were noted on the hirsutism score and other steroid levels.

CONCLUSION

In women with PCOS treatment with metformin is effective in the lowering of hyperinsulinemia and hyperandrogenemia. In most women metformin improves the menstrual pattern, but has no effect on hirsutism.