A study on wear failure analysis of tungsten carbide hardfacing on carbon steel blade in a digester tank

This paper addresses wear failure analysis of tungsten carbide (WC) hardfacing on a carbon steel blade known as the continuous digester blade (CD blade). The CD blade was placed in a digester tank to mix ilmenite ore with sulphuric acid as part of a production process. Tungsten carbide hardfacing was applied on the CD blade to improve its wear resistance while the CD blade was exposed to an abrasive and acidic environment. Failure analysis was car-ried out on the hardfaced CD blade in order to improve its wear resistance and lifetime. A thickness and hardness comparison study was conducted on worn and unworn specimens from the CD blades. The carbide distribution along with elemental composition analysis of the hardfaced CD blade specimens was examined using scanning electron microscopy and energy-dispersive spectroscopy. The investigation revealed that an inconsistent hardfacing thickness was welded around the CD blade. Minimum coating thickness was found at the edges of the blade surfaces causing failure to the blades as the bare carbon steel blades were exposed to the mixed environment. The wear resistance of the CD blade can be improved by distributing the carbide uniformly on the hardfaced coating. Applying extra coating coverage at the critical edge will prevent the exposure of bare carbon steel blade, thus increasing the CD blade lifetime

Corneal Sensation and Subbasal Nerve Alterations in Patients with Herpes Simplex Keratitis

Purpose To study and correlate corneal sensation in patients with herpes simplex keratitis (HSK) with density and morphology of subbasal corneal nerves by in vivo confocal microscopy (IVCM). Design Prospective, cross-sectional, controlled, single-center study. Participants Thirty-one eyes with the diagnosis of acute (n=7) or chronic (n=24) HSK and the contralateral clinically unaffected eyes were studied and compared to normal controls (n=15). Methods IVCM (Confoscan 4, Nidek) and corneal esthesiometry (Cochet-Bonnet) of the central cornea were performed bilaterally in all patients and controls. Patients were grouped into normal (>5.5 cm), mild (>2.5 to 5.5cm) and severe (≤2.5 cm) loss of sensation. Main Outcome Measures Changes in corneal nerve density, total nerve number, main nerve trunks, branching and tortuosity were evaluated after IVCM and correlated to corneal sensation, disease duration, and number of recurrences. Results HSK eyes, as compared to controls, demonstrated significant (p<0.001) decrease in mean nerve density (448.9±409.3 vs. 2,258.4±989.0 μm/frame), total nerve number (5.2±4.5 vs. 13.1±3.8), main nerve trunks (2.3±1.6 vs. 4.7±1.2) and nerve branches (3.2 ± 4.3 vs. 9.8±3.3). In contralateral unaffected eyes, mean nerve density (992.7±465.0 μm/frame), total nerve number (7.8±3.3), and branches (4.5±2.3) were significantly decreased as compared to controls (p<0.002). Reduced nerve density, total nerve count and main trunks in HSK eyes were significantly correlated with corneal sensation across all subgroups (p<0.001). Nerve density decreased within days of infection and was correlated to frequency of episodes in patients with HSK (p<0.02). Conclusions In vivo confocal microscopy reveals that the loss of corneal sensation in HSK correlates strongly with profound diminishment of the subbasal nerve plexus after herpes simplex virus (HSV) infection. Surprisingly, the contralateral clinically unaffected eyes also demonstrated a diminishment of the subbasal nerve plexus, as compared to normal subjects, revealing bilateral nerve alteration in an apparently unilateral disease

Unilateral Herpes Zoster Ophthalmicus Results in Bilateral Corneal Nerve Alteration

Purpose Herpes zoster ophthalmicus (HZO), thought to be a unilateral disease, results in loss of corneal sensation, leading to neurotrophic keratopathy. This study aimed to analyze bilateral corneal nerve changes in patients with HZO by in vivo confocal microscopy (IVCM) and their correlation with corneal sensation as a measure of nerve function. Design Prospective, cross-sectional, controlled, single-center study. Participants Twenty-seven eyes with the diagnosis of HZO and their contralateral clinically unaffected eyes were studied and compared with normal controls (n = 15). Methods In vivo confocal microscopy (Confoscan 4; Nidek Technologies, Gamagori, Japan) and corneal esthesiometry (Cochet-Bonnet; Luneau Ophthalmologie, Chartres, France) of the central cornea were performed bilaterally in all patients and controls. Patients were grouped into normal (>5.5 cm), mild (>2.5–5.5 cm), and severe (<2.5 cm) loss of sensation. Main Outcome Measures Changes in corneal nerve density, total nerve number, main nerve trunks, branching, and tortuosity were evaluated after IVCM and were correlated to corneal sensation, disease duration, and number of recurrences. Results Eyes with herpes zoster ophthalmicus had a significant (P<0.001) decrease in total nerve length (595.8±358.1 vs. 2258.4±989.0 μm/frame), total number of nerves (5.4±2.8 vs. 13.1±3.8), number of main nerve trunks (2.3±1.1 vs. 4.7±1.2), and number of nerve branches (3.2±2.3 vs. 8.4±3.7) as compared with controls. In the contralateral clinically unaffected eyes, total nerve length (1053.1±441.4 μm/frame), total number of nerves (8.3±2.9), and main nerve trunks (3.1±1.0) also were decreased significantly as compared with controls (P<0.01). Reduced nerve density, total nerve count, main trunks, and tortuosity was correlated significantly with corneal sensation across all subgroups (P<0.001). Conclusions Patients with unilateral HZO demonstrated a profound and significant bilateral loss of the corneal nerve plexus as compared with controls, demonstrating bilateral changes in a clinically unilateral disease. Loss of corneal sensation strongly correlated with subbasal nerve plexus alterations as shown by IVCM

Rapid rotational foam molding of integral skin polypropylene cellular composites

Rapid Rotational Foam Molding (RRFM) is a novel patent-pending process that was designed and developed to maximize the synergistic effects resulting from the deliberate combination of extrusion and rotational foam molding and thereby serve as a time-andenergy efficient technology for the manufacture of integral-skin rotationally molded foams of high quality. This thesis presents a thorough study of the scientific and engineering aspects related to the evolution of the RRFM process and its feasibility. This innovative processing technology was assessed and verified through a battery of planned experimental trials conducted utilizing an in-house custom-built industrial-grade lab-scale experimental setup. The experimental trials involved a variety of polypropylene (PP)- based foamable formulations with a chemical blowing agent (CBA) that were compounded and processed by utilizing an extruder and then foamed and injected as a foamed core, instantly, into the cavity of a suitable non-chilled rotationally molded hollow shell made of non-foamed pulverized PP grades. The investigated mold shapes included a cylindrical shaped mold and a rectangular flat shaped mold. The obtained moldings were examined for the quality of the skin surface, the skin-foam interface, and the achieved foam morphologies that were characterized in terms of foam density, average cell size, and average cell density. Optimal processing parameters were successfully determined for three different PP skin-foam formulation combinations. The accomplished reduction in processing time and energy consumption by implementing RRFM were substantial. A variety of processing impediments that hindered the efficiency of the single-charge conventional rotational foam molding practice were resolved by implementing RRFM; these include: the foam/skin invasion into the skin/foam layer of the manufactured article and the premature decomposition of CBA during compounding or subsequent rotational foam molding processing steps

Optimisation of pH of cadmium chloride post-growth-treatment in processing CDS/CDTE based thin film solar cells

The role of Chlorine-based activation in the production of high quality CdS/CdTe photovoltaic have been well discussed and explored with an overlook of the effect of Cadmium chloride (CdCl2) post-growth treatment acidity on the property of the fabricated devices. This work focuses on the optimisation of CdCl2 post-growth treatment pH as it affects both the material and fabricated device properties of all-electrodeposited multilayer glass/FTO/n-CdS/n-CdTe/p-CdTe configuration. CdCl2 treatments with acidity ranging from pH1 to pH4 were explored. The properties of the ensued CdTe layer were explored using optical, morphological, compositional structural and electrical property analysis, while, the effect on fabricated multilayer glass/FTO/n-CdS/n-CdTe/p-CdTe configuration were also explored using both I-V and C-V measurements. Highest improvements in the optical, morphological, compositional and structural were observed at pH2 CdCl2 post-growth treatment with an improvement in absorption edge, grain size, crystallinity and crystallite size. Conductivity type conversions from n-CdTe to p-CdTe, increase in pin-hole density and collapse of the absorption edge were observed after pH1 CdCl2 treatment. The highest fabricated solar cell efficiency of 13% was achieved using pH2 CdCl2 treatment as compared to other pH values explored

Ovarian carcinoma associated with pregnancy: A clinicopathologic analysis of 23 cases and review of the literature

<p>Abstract</p> <p>Background</p> <p>The aim of this study was to analyze and describe cases of ovarian cancer in pregnant women treated at our center and to review the literature concerned, and to discuss the rationale for therapy.</p> <p>Methods</p> <p>Twenty-Three patients of ovarian malignancies during pregnancy were treated at Vali- Asr Hospital between 1991 and 2002. Data on treatment and follow-up were evaluated.</p> <p>Results</p> <p>The incidence of ovarian carcinoma associated with pregnancy in our series was 0.083/1000 deliveries. Eleven (47.8%) were found with ovarian malignant germ cell tumors, five (21.7%) with low malignant potential tumors, four (17.4%) with invasive epithelial tumors, and three (13%) with sex cord stromal tumors. Seventeen (73.9%) of the patients were diagnosed in stage I and had complete remission. Five of the six in advanced stage died. The mean follow-up was 36.3 months. The prognosis was significantly related with stage and histological type (<it>P </it>< 0.05). Sixteen healthy live babies were recorded in this group, and two premature newborn died of respiratory distress syndrome. Chemotherapy was administered to 44% of the patients, in two cases during pregnancy. Overall survival at 5 years was 61%. In most of case conservative surgical treatment could be performed with adequate staging and debulking.</p> <p>Conclusion</p> <p>Early finding of ascitis by ultrasound and persistent large ovarian mass during pregnancy may be related to malignancy and advanced stage. Pregnant women in advanced stage of ovarian cancer seem to have poor prognosis.</p

Scientific complications and controversies noted in the field of CdS/CdTe thin film solar cells and the way forward for further development

Cadmium telluride-based solar cell is the most successfully commercialised thin film solar cell today. The laboratory-scale small devices have achieved ~ 22%, and commercial solar panels have reached ~ 18% conversion efficiencies. However, there are various technical complications and some notable scientific contradictions that appear in the scientific literature published since the early 1970s. This review paper discusses some of these major complications and controversies in order to focus future research on issues of material growth and characterisation, post-growth processing, device architectures and interpretation of the results. Although CdTe can be grown using more than 14 different growth techniques, successful commercialisation has been taken place using close-space sublimation and electrodeposition techniques only. The experimental results presented in this review are mainly based on electrodeposition. Historical trends of research and commercial successes have also been discussed compared to the timeline of novel breakthroughs in this field. Deeper understanding of these issues may lead to further increase in conversion efficiencies of this solar cell. Some novel ideas for further development of thin film solar cells are also discussed towards the end of this paper