Cutting Forces and Tool Wear Investigation during Turning of Sintered Nickel-Cobalt Alloy with CBN Tools

This article describes issues related to the machining of parts made of sintered nickel-cobalt alloy. Longitudinal turning with a CBN (cubic boron nitride) tool was analyzed. The results of experiments showed the influence of cutting parameters in the field of finishing machining on the values of cutting forces and specific cutting force, taking into account the wear of the cutting edge. Measurements and analysis of the topography and roughness parameters of the machined surface, as well as the cutting tool wear, were presented. The microscopic examination showed that the average grain size of the sintered nickel-cobalt alloy was 3.22 ± 0.1 (μm). The presence of the hardening state variability of the material during machining, as well as the value of the cutting force fluctuation as a function of the tool wear VB, were stated. The specific cutting force values increased to a small degree for the tool wear in the range of VB = 0–0.2 mm, and reached similar values in the range k_c = 5500–7500 N/mm². The specific cutting force values increased significantly for wear VB > 0.2 mm and were characterized by a large variability. The occurring phenomena were analyzed and several explanations were proposed. A recommendation was developed for the machining of parts made of sintered nickel-cobalt alloy. The Taguchi method was used in the experiment methodology.     

Broadband Near-Infrared Luminescence in Lead Germanate Glass Triply Doped with Yb3+/Er3+/Tm3+

This paper deals with broadband near-infrared luminescence properties of lead germanate glass triply doped with Yb³⁺/Er³⁺/Tm³⁺. Samples were excited at 800 nm and 975 nm. Their emission intensities and lifetimes depend significantly on Er³⁺ and Tm³⁺ concentrations. For samples excited at 800 nm, broadband emissions corresponding to the overlapped ³H₄ → ³F₄ (Tm³⁺) and ⁴I_13/2 → ⁴I_15/2 (Er³⁺) transitions centered at 1.45 µm and 1.5 µm was identified. Measurements of decay curves confirm reduction of ³H₄ (Tm³⁺), ²F_5/2 (Yb³⁺) and ⁴I_13/2 (Er³⁺) luminescence lifetimes and the presence of energy-transfer processes. The maximal spectral bandwidth equal to 269 nm for the ³F₄ → ³H₆ transition of Tm³⁺ suggests that our glass co-doped with Yb³⁺/Er³⁺/Tm³⁺ is a good candidate for broadband near-infrared emission. The energy transfer from ⁴I_13/2 (Er³⁺) to ³F₄ (Tm³⁺) and cross-relaxation processes are responsible for the enhancement of broadband luminescence near 1.8 µm attributed to the ³F₄ → ³H₆ transition of thulium ions in lead germanate glass under excitation of Yb³⁺ ions at 975 nm.     

PSP-CBS with Dopamine Deficiency in a Female with a <Emphasis Type="Italic">FMR1</Emphasis> Premutation

Premutations in the fragile X mental retardation 1 (FMR1) gene cause fragile X-associated tremor/ataxia syndrome (FXTAS) and FMR1-related primary ovarian insufficiency (POI). Female FMR1 premutation carriers rarely develop motor features. Dual pathology is an emerging phenomenon among FMR1 premutation carriers. Here, we describe a family affected by FMR1-related disorders in which the female index case has developed a rapidly progressive and disabling syndrome of atypical parkinsonism. This syndrome consists of early onset postural instability, echolalia, dystonia, and varying types of apraxia like early onset orobuccal apraxia and oculomotor apraxia. She has also developed supranuclear gaze palsy, increased latency of saccade initiation, and slow saccades. These features are compatible with progressive supranuclear palsy (PSP) of a corticobasal syndrome (CBS) variant. Imaging displays a marked reduction of presynaptic dopaminergic uptake and cerebrospinal fluid analysis showed reduced dopamine metabolism; however, the patient is unresponsive to levodopa. Midbrain atrophy (“hummingbird sign”) and mild cerebellar atrophy were found on brain MRI. Her father was affected by a typical FXTAS presentation but also displayed dopamine deficiency along with the hummingbird sign. The mechanisms by which FMR1 premutations predispose to atypical parkinsonism and dopamine deficiency await further elucidation.     

Trace elements in seminal plasma of men from infertile couples

Introduction

An analysis of lead, zinc, cadmium and other trace elements in semen of men from infertile couples was performed to determine the association between abnormal semen parameters and enviromental or occupational exposure to some trace metals.

Material and methods

Presence of manganese, cobalt, nickel, copper, zinc, molybdenum, cadmium, tin and lead was measured in seminal plasma of 34 men from infertile couples using spectrometry with time-of-flight analysis. Correlations among sperm parameters and trace metals were determined using cluster analysis and Pearson''s correlation coefficient.

Results

Abnormally high concentrations of lead, cadmium, zinc and cobalt were found in 23 seminal plasma of men from infertile couples. The most consistent evidence was determined for an association between high cadmium concentration in seminal plasma and sperm count, motility and morphology below reference limits (p < 0.01). A correlation of significantly increased tin level and reduced sperm count in semen of men with limited fertility potential was observed (p = 0.04).

Conclusions

In our study we observed a correlation of tin level with sperm count in semen of men with limited fertility potential.     

The influence of a ten-week Nordic walking training-rehabilitation program on the level of lipids in blood in overweight and obese postmenopausal women

[Purpose] The aim of this study was to evaluate the effect of a ten-week Nordic Walking (NW) rehabilitation program on chosen anthropometric parameters and the level of basic lipids in overweight and obese postmenopausal women’s blood. [Subjects and Methods] The subjects were 32 women aged 50–68 (average: 59.7 ± 5.9 years). The study was carried out following a non-randomized model and entailed NW rehabilitation 5 times a week, which lasted for 10 weeks, as well as a low-calorie 1,500 kcal diet. The therapeutic results of the study were measured through changes in anthropometric and biochemical parameters. The results were subjected to a statistical analysis. [Results] After 10 weeks of NW rehabilitation it was observed that participants lost weight and their body mass index dropped. Additionally, whereas levels of total cholesterol, LDL and triglycerides dropped, and the level of HDL increased. [Conclusion] Rehabilitation carried out according to the NW model resulted in statistically significant changes in basic lipids in blood which, considerably increased the percentage of persons who achieved the recommended level of blood lipids. Obese persons were characterised by a smaller rehabilitation weight loss. More intense workouts and cooperation with a dietician are required.Key words: Nordic walking, Obesity, Blood lipids     

Autofluorescence endoscopy for detection of high-grade dysplasia in short-segment Barrett's esophagus

BACKGROUND: The occurrence of precancerous lesions, such as high-grade dysplasia, in patients with short-segment Barrett's esophagus is controversial. This study assessed the efficacy of autofluorescence endoscopy for detection of high-grade dysplasia in short-segment Barrett's esophagus. METHODS: A total of 34 patients (28 men, 6 women; age range 40-77 years) with histopathologically proven short-segment Barrett's esophagus were studied. Autofluorescence endoscopy was performed by using monochromatized blue light (425-455 nm) filtered from a conventional xenon light source. A total of 136 and 109 biopsy specimens were taken from Barrett's mucosa under control, respectively, white light endoscopy and autofluorescence endoscopy. RESULTS: High-grade dysplasia was found in 9 (8.3%) autofluorescence-guided biopsy specimens, which was significantly greater than the number of white light endoscopy-guided biopsy specimens with this finding (one positive biopsy specimen, 0.7% of total biopsy specimens obtained). Autofluorescence endoscopy detected high-grade dysplasia in 7 patients, 6 more than were identified with white light endoscopy. In the one patient with high-grade dysplasia detected by white light endoscopy-guided biopsy specimens, autofluorescence-guided biopsy specimens revealed only low-grade dysplasia. CONCLUSION: Autofluorescence endoscopy in patients with short-segment Barrett's esophagus increases the detection rate of high-grade dysplasia.