Important Issues of Needle Insertion into Soft Tissue

Needle insertion procedures have been gaining in popularity with medical communities and patients over the recent years. Currently, their applications span a wide range of diagnostic and therapeutic procedures and there is still a growing tendency toward integrating needle insertion into other procedures and surgeries. Its less invasive nature, which is performed locally on the body, largely explains this growing trend. This results in less intraoperative tissue damage and shorter post-operative recovery time. Many procedures like biopsy, deep brain stimulation, and cancer treatments are done using needles/catheters. However, despite all the advantages of needle insertion procedures, the inherent complications resulting from them, such as tissue deformation, needle deflection, tissue inhomogeneity, patient variability, and associated uncertainty, can hardly be missed. Therefore, a needle insertion procedure requires that we address promising aspects and associated concerns. Against this backdrop, this paper provides a review of some of the main issues associated with a generic needle insertion procedure.     

Rheological and mechanical characteristics of low density polyethylene/ethylene‐vinyl acetate/organoclay nanocomposites

Attempts were made to trace the effect of organoclay (OC) on the rheological and mechanical behaviors of the low density polyethylene (LDPE)/ethylene‐vinyl acetate (EVA) blends. To do this effectively, in addition to LDPE/EVA/OC system, pure LDPE and LDPE/EVA blends were also examined as model systems. The rheological behavior was determined by the capillary rheometer. Morphological characterization was also carried out using X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and theoretical approach based on interfacial energies. Shear viscosity, tensile strength and elastic modulus of LDPE/EVA were found to decrease by increasing the EVA content, while for LDPE/EVA/OC ternary nanocomposites, such properties showed an increase by increasing the content of EVA. Such behavior was explained by the morphological characteristic of the system in which OC was mainly intercalated/exfoliated in the EVA phase. This morphological characteristic was corroborated by the XRD, TEM and interfacial energies data. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers     

Investigation of nonlinear dynamic behavior of a capacitive carbon nano-tube based electromechanical switch considering van der Waals force

Microsystem Technologies - In this study, nonlinear dynamic behavior of a capacitive carbon nano-tube switch is investigated considering van der Waals (vdW) force. The carbon nano-tube is...     

Development of a dispersive liquid-liquid microextraction method for the determination of polychlorinated biphenyls in water

A very simple and powerful microextraction procedure, the dispersive liquid-liquid microextraction (DLLME), was used for the determination of the content of 10 polychlorinated biphenyls (PCBs) in water samples, using gas chromatography coupled with electron-capture detection (GC-ECD). The appropriate amount of acetone (disperser solvent) and chlorobenzene (extraction solvent) at the microlevel volume was used for this procedure. The conditions for the microextraction performance were investigated and optimized. The optimized method exhibited a good linearity (R(2)>0.996) over the studied range (0.005-2mugL(-1)), illustrating a satisfactory precision level with R.S.D. values between 4.1% and 11.0%. The values of the detection limit (S/N=3) were found to be lower than 0.002mugL(-1). Furthermore, a large enrichment factor for the analytes (up to a 540-fold) was achieved in a very short time for only a 5.00-mL water sample. The effectiveness of the method towards real samples was tested by analyzing well, river and seawater samples. The relative recoveries of the well, river and seawater samples, which had been spiked with different levels of PCBs were equal to 92.0-114.0%, 97.0-102.0% and 96.0-103.0%, respectively. The attained results demonstrated that DLLME combined with GC-ECD was a fast and inexpensive technique for the PCBs determination in water samples.     

Serum Small Dense Low-density Lipoprotein Concentrations are Elevated in Patients with Significant Coronary Artery Stenosis and are Related to Features of the Metabolic Syndrome

Serum small dense low-density lipoprotein (sd-LDL) concentrations were measured in patients with angiographically defined coronary artery disease (CAD) and compared to concentrations in healthy subjects. Five hundred and seventy patients with stable CAD were divided into CAD? and CAD+ based on angiography. Patients in whom stenosis was <50?% in diameter were classified as having a ??normal?? angiogram (CAD?), otherwise the patients were allocated to the CAD+ group. The CAD+ group was further subcategorized into single-, double- and triple-vessel disease (VD). Serum sd-LDL concentrations were significantly lower in controls compared with CAD+ and CAD? patients (P?<?0.001). Moreover, CAD+ patients had higher concentrations of sd-LDL than CAD? patients (P?<?0.01). sd-LDL levels were not significantly associated with severity of CAD defined by the number of stenosed coronary arteries (P?=?0.245). All participants were also categorized into subgroups with or without metabolic syndrome. Subjects with metabolic syndrome had higher levels of sd-LDL than subjects without metabolic syndrome (P?<?0.01). Multiple linear regressions showed that in CAD patients, triacylglycerol, total-cholesterol, body mass index, and waist circumferences were the most important determinants of serum sd-LDL concentrations. We found that sd-LDL levels were significantly higher in patients presenting with symptoms of CAD. Moreover, patients with significant stenosis of their coronary arteries (>50?% stenosis) had higher levels of sd-LDL compared to patients without significant lesions.