Direct measurement of tissue blood flow and metabolism with diffuse optics

Diffuse optics has proven useful for quantitative assessment of tissue oxy- and deoxyhaemoglobin concentrations and, more recently, for measurement of microvascular blood flow. In this paper, we focus on the flow monitoring technique: diffuse correlation spectroscopy (DCS). Representative clinical and pre-clinical studies from our laboratory illustrate the potential of DCS. Validation of DCS blood flow indices in human brain and muscle is presented. Comparison of DCS with arterial spin-labelled MRI, xenon-CT and Doppler ultrasound shows good agreement (0.50相似文献   

Huge ossified crust-like subdural hematoma covering the hemisphere and causing acute signs of increased intracranial pressure

We report the successful removal of an ossified crust-like chronic subdural hematoma (SDH) covering the hemisphere in a 16-year-old boy. In this article, the importance of the surgical approach is stressed, and the rarity of this condition in the neurosurgical literature is also outlined.     

Cerebrovascular occlusive disease: hydatidosis

We reviewed six patients with cerebral hydatid embolism from the heart. Although hydatid disease is becoming less common in the world as a whole, it should be considered in the differential diagnosis of embolic stroke in children, especially in the infested areas where hydatidosis is endemic.     

Transient "cerebellar" mutism

The term "cerebellar mutism" refers to a specific disorder in which a complete but transient loss of speech, followed by dysarthria, occurs following resection of intrinsic posterior cranial fossa tumors or cerebellar hemorrhages, or upon trauma. Although it is well known that the lack of long-tract findings and cranial nerve (CN) involvement is the rule, the pathophysiology of cerebellar mutism has not been clearly elucidated. A review of the relevant literature disclosed 93 patients with this condition, the majority of these being in the pediatric age group. The neuropathological findings were as follows: 57 primitive neuroectodermal tumors (PNET), 19 astrocytomas, 10 ependymomas, 5 vascular malformations, 1 metastatic tumor, and 1 traumatic injury. The interval before the onset of mutism ranged from 0 to 168 h (mean 40.9 h). The mutism lasted from 1 to 168 days (mean 37.6 days). Subsequent dysarthria was present in 75 (80%) of the 93 patients. In this article, some specific recent illustrative reports are presented, and the concept of the role of the cerebellum in language and cognition is discussed. With these data as our point of departure, various hypotheses that have been advanced to explain the pathogenesis of this transient speech disorder are analyzed. The findings of the study suggest that the cause of the cerebellar mutism is the ischemia caused by vasospasm, as it usually developed after a latent period.     

A Study of Pb-Doping Effect on Structural,Optical, and Morphological Properties of ZnO Thin Films Deposited by Sol–Gel Spin Coating

In our study, undoped and lead (Pb)-doped ZnO thin films were deposited by sol–gel spin-coating technique and the structural, morphological, and optical properties of the films were investigated as a function of Pb doping which was changed from 0 to 4 at. pct with 1 at. pct step. The XRD results exhibited that the films had a hexagonal wurtzite structure with (002) preferential orientation in all dopant ratios. The grain size values of Pb-doped films were lower than that of undoped ZnO, but the increase in strain and dislocation density values were observed with Pb doping. Detailed optical analysis showed that the average transmittance of all films varied between about 90 and 99 pct and the absorption edge of undoped ZnO film shifted from longer wavelength to short wavelengths (blue shift) with Pb doping. The optical band gap and Urbach energy values of undoped ZnO increased from 3.283 eV and 63 meV to 3.331 eV and 88 meV with increasing Pb doping ratio. But steepness parameter values showed reversely variation with increasing Pb doping. The AFM images expressed that the films had homogenous nanoparticle distribution on the surface and particle size of ZnO decreased with Pb doping ratio. These results suggested that undoped and Pb-doped ZnO thin films could be used in many technological areas.     

Secondary extradural spinal tumours in children

Secondary extradural spinal tumours are very rare, but they comprise most of the extradural neoplasms seen in infancy and childhood. Thirty-nine patients with this type of secondary tumour were treated in our hospital between 1965 and 1991. The diagnosis was proved by biopsy in every case. Following surgical decompression, all 35 survivors had radiotherapy and/or chemotherapy. Their outcome is reported.     

Exfoliation targeted toughness enhancement in polypropylene‐blend‐ montmorillonite nanocomposites

BACKGROUND: Both exfoliated and toughened polypropylene‐blend‐montmorillonite (PP/MMT) nanocomposites were prepared by melt extrusion in a twin‐screw extruder. Special attention was paid to the enhancement of clay exfoliation and toughness properties of PP by the introduction of a rubber in the form of compatibilizer toughener: ethylene propylene diene‐based rubber grafted with maleic anhydride (EPDM‐g‐MA). RESULTS: The resultant nanocomposites were characterized using X‐ray diffraction, atomic force microscopy, scanning electron microscopy, thermogravimetric analysis, dynamic mechanical analysis and Izod impact testing methods. It was found that the desired exfoliated nanocomposite structure could be achieved for all compatibilizer to organoclay ratios as well as clay loadings. Moreover, a mechanism involving a decreased size of rubber domains surrounded with nanolayers as well as exfoliation of the nanolayers in the PP matrix was found to be responsible for a dramatic increase in impact resistance of the nanocomposites. CONCLUSION: Improved thermal and dynamic mechanical properties of the resultant nanocomposites promise to open the way for highly toughened super PPs via nanocomposite assemblies even with very low degrees of loading. Copyright © 2008 Society of Chemical Industry     

Properties of masonry blocks produced with waste limestone sawdust and glass powder

Large amounts of waste accumulate in every year in all countries which have been running limestone quarries. The majority of waste limestone sawdust (WLS) or dust is abandoned, and causes certain serious problems such as environmental problems and health hazards. This study has been conducted through basic experimental research in order to analyze the usage possibilities of WLS for producing masonry blocks. Two types of masonry blocks are produced for this study. The first type of masonry blocks includes WLS and a small amount of Portland cement. The second type of masonry blocks is composed of WLS with a small amount of Portland cement, and waste glass powder (WGP) at various proportions. The compressive strength and rupture modulus of all masonry blocks are greater than 24.9 MPa and 3.94 MPa, respectively. Compressive strength and rupture modulus’ values in the WLS masonry blocks with WGP are higher than those of control masonry block without WGP. Preliminary results show WLS with and without WGP can be used for the production of moulded masonry blocks with acceptable mechanical and physical properties. The data obtained from the first stage of this study show that there is a great potential for the utilization of WLS and WGP in masonry blocks.     

Aquifer thermal storage (ATES) for air-conditioning of a supermarket in Turkey

A heating, ventilation and air-conditioning (HVAC) system with integrated aquifer thermal energy storage (ATES) was designed for a supermarket building in Mersin, a city near the Mediterranean coast in Turkey (36° 49′ N and 34° 36′ E). This is the first ATES application carried out in Turkey. The peak cooling and heating loads of the building are 195 and 74 kW, respectively. The general objective of the system is to use the groundwater from the aquifer to cool down the condenser of the HVAC system and at the same time storing this waste heat in the aquifer. Cooling with groundwater at around 18 °C instead of utilizing outside summer air at 30–35 °C decreases consumption of electrical energy significantly. In addition, stored heat can be recovered when it is needed in winter. The HVAC system with ATES started operation in August 2001 in cooling mode with an average coefficient of performance (COP) of 4.18, which is almost 60% higher than a conventional system.