Effect of tool geometry on friction stir spot welding of polypropylene sheets

The effects of tool geometry and properties on friction stir spot welding properties of polypropylene sheets were studied. Four different tool pin geometries, with varying pin angles, pin lengths, shoulder diameters and shoulder angles were used for friction stir spot welding. All the welding operations were done at the room temperature. Lap-shear tensile tests were carried out to find the weld static strength. Weld cross section appearance observations were also done. From the experiments the effect of tool geometry on friction stir spot weld formation and weld strength were determined. The optimum tool geometry for 4 mm thick polypropylene sheets were determined. The tapered cylindrical pin gave the biggest and the straight cylindrical pin gave the lowest lap-shear fracture load

Caprice Hotel: Transforming Islam on the Aegean Coast

In summer 1996, Turkish newspapers, especially those addressing a religious audience, reported the introduction of a new space of consumption: a fivestar hotel in Didim (Aydin) designed on the basis of Islamic rules. Fadil Akgunduz, owner of the hotel, announced in a press release on the opening of the facility that this investment was an attempt to enable religious-conservative people to benefit from the blessings of God and use their right to enjoy the worldly pleasures in accordance with their religious beliefs (Yeni Safak Daily, 3 July 1996)

WC/Co-Ti Kompozitlerinin ısıl ve elastik özelliklerinin ultrasonik dalga hızı ile ilişkisi

In this study,it is aimed to produce various composites and reveal their physical properties. Tungsten carbide (WC) powder and the two of cobalt (Co) and titanium (Ti) powders as binder phase have been used for the preparation of WC-Co-Ti ceramic-metal composite with powder metallurgy. Two different ultrasonic non-destructive techniques were employed to measure the mechanical wave velocity in WCCo-Ti composites. The study was performed on various specimens with different WCx content at the range from 60 to 80% and Co/Ti content in 3:1, 1:1 and 1:3 groups. The WCx content in examined materials was determined using the standard destructive analysis. The Young modulus (E) of the produced composites and the ultrasonic velocity measured through ultrasonic pulse-echo method and immersion method. Thermal conductivity of samples has been measured via hot disk method. The relation between the Young modulus' values with ultrasonic wave velocity, which is obtained through two different methods and thermal conductivity has been physically examined and the results have been compared with the literature

Prevalence of oral mucosal lesions from birth to two years

Objective: The purpose of this study was to determine the prevalence of lesions of the oral mucosa from birth to two years in Turkish pediatric patients .Materials and Methods: A total of 299 infants from newborn to two years of  age were evaluated from the Outpatient Clinics of the Pediatric Department, in the Fatih University Hospital, Ankara, Turkey. The mucosal lesions were documented. The data were presented as percentages and for categorical comparisons Chi-square or Fisher’s Exact test were used. A P-value less than 0.05 was considered statistically significant.Results: Of the 299 infants, mucosal lesions were seen in only 65 (21.27%). In the study, the most common lesions were candidiasis (10.70%), Ebstein’s pearls (2.68%), and geographic tongue (2.68%). The frequency of children with mucosal alterations was higher in the group of children from two to twelve months.Conclusions: Although the lesions that were found the most in our study were benign lesions, unrelated to systemic diseases, we still believe that oral mucosal lesions can be a sign of a systemic or dermatological disease in infants, which affects the oral feeding of the infants. Routine examination of the oral mucosa should be a part of the pediatric examination

Effect of aging on H-reflex response to fatigue

Injury as a result of tripping is relatively common among older people. The risk of falling increases with fatigue and of importance is the ability to dorsiflex the foot through timely activation of the tibialis anterior (TA) muscle to ensure the foot clears the ground, or an obstacle, during the swing phase of walking. We, therefore, questioned whether the muscle spindle input to the motoneurons alters with ongoing fatigue in older people. We electrically stimulated the common peroneal nerve to assess the TA primary afferent efficacy using H-reflex before, immediately following and after a fatiguing maximal isometric contraction. M-response was kept unchanged throughout the experiment to ensure a similar stimulus intensity was delivered across time points. H-reflex increased significantly while the TA muscle was in a state of fatigue for the younger participants but tended to decrease with increasing age. The main contributor to the tonicity of TA muscle, i.e., excitatory synapses of spindle primary endings of motoneurons that innervate TA muscle, tend to lose their efficacy during fatigue in the older individuals but increased efficiency in the majority of the younger people. Since TA muscle is the main dorsiflexor of the foot and it needs to be active during the swing phase of stepping to prevent tripping, older individuals become more susceptible to falling when their muscles are fatigued. This finding may help improve devices/treatments to overcome the problem of tripping among older individuals

Fluence of thulium laser system in skin ablation

Tm:YAP laser system at power levels up to 1.2 W at 1980 nm was established in both continuous-wave and modulated modes of operation. The fluence effect of the laser system for skin ablation was analyzed by histology analysis with Wistar rat skin tissues. Thermally altered length, thermally altered area, ablation area, and ablation depth parameters were measured on histology images of skin samples just after the laser operation and after four-day healing period. Continuous-wave mode of operation provided higher thermal effects on the skin samples. Lower fluence levels were found for efficient ablation effect. © 2010 IEEE

Development of a thulium (Tm:YAP) laser system for brain tissue ablation

In this study, a thulium (Tm:YAP) laser system was developed for brain surgery applications. As the Tm:YAP laser is a continuous-wave laser delivered via silica fibers, it would have great potential for stereotaxic neurosurgery with highest local absorption in the IR region. The laser system developed in this study allowed the user to set the power level, exposure time, and modulation parameters (pulse width and on-off cycles). The Tm:YAP laser beam (200-600 mW, 69-208 W/cm 2) was delivered from a distance of 2 mm to cortical and subcortical regions of ex-vivo Wistar rat brain tissue samples via a 200-μm-core optical fiber. The system performance, dosimetry study, and ablation characteristics of the Tm:YAP laser were tested at different power levels by maximizing the therapeutic effects and minimizing unwanted thermal side-effects. The coagulation and ablation diameters were measured under microscope. The maximum ablation efficiency (100 × ablation diameter/coagulation diameter) was obtained when the Tm:YAP laser system was operated at 200 mW for 10 s. At this laser dose, the ablation efficiency was found to be 71.4% and 58.7% for cortical and subcortical regions, respectively. The fiber-coupled Tm:YAP laser system in hence proposed for the delivery of photothermal therapies in medical applications. © 2011 Springer-Verlag London Ltd

Zinc sulfate as an adjunct to methylphenidate for the treatment of attention deficit hyperactivity disorder in children: A double blind and randomized trial [ISRCTN64132371]

BACKGROUND: Attention-deficit hyperactivity disorder is an early-onset, clinically heterogenous disorder of inattention, hyperactivity, and impulsiveness. The diagnosis and treatment of attention-deficit hyperactivity disorder continues to raise controversy, and, there is also an increase in treatment options. In this 6-week double blind, placebo controlled-trial, we assessed the effects of zinc plus methylphenidate in the treatment of children with attention deficit hyperactivity disorder. To the best of our knowledge, this study is the first double blind and placebo controlled clinical trial assessing the adjunctive role of zinc in ADHD. METHODS: Our subjects were 44 outpatient children (26 boys and 18 girls) between the ages of 5–11 (mean ± SD was 7.88 ± 1.67) who clearly met the DSM IV diagnostic criteria for attention-deficit hyperactivity disorder and they were randomized to methylphenidate 1 mg/kg/day + zinc sulfate 55 mg/day (with approximately 15 mg zinc element) (group 1) and methylphenidate 1 mg/kg/day + placebo (sucrose 55 mg) (group 2) for a 6 week double blind clinical trial. The principal measure of the outcome was the Teacher and Parent ADHD Rating Scale. Patients were assessed by a child psychiatrist at baseline, 14, 28 and 42 days after the medication started. RESULTS: The present study shows the Parent and Teacher Rating Scale scores improved with zinc sulfate over this 6-week, double blind and placebo controlled trial. The behavior of the two treatments was not homogeneous across the time. The difference between the two protocols was significant as indicated by the effect on the group, the between-subjects factor (F = 4.15, d.f. = 1, P = 0.04; F = 4.50, d.f. = 1, P = 0.04 respectively). The difference between the two groups in the frequency of side effects was not significant. CONCLUSIONS: This double-blind, placebo-controlled study demonstrated that zinc as a supplementary medication might be beneficial in the treatment of children with attention-deficit hyperactivity disorder. However, further investigations and different doses of zinc are required to replicate these findings in children with ADHD