Photovoltaic and impedance spectroscopy analysis of p–n like junction for dye sensitized solar cell

A dye-sensitized solar cell based on nanostructure TiO₂ and PCBM:P3HT blend was fabricated and the photovoltaic and impedance spectroscopy properties of the solar cell were investigated. The solar cell gives a short circuit current density of 0.75 mA/cm² and an open circuit voltage of 0.60 V under AM1.5. The photovoltage of the solar cell was greatly enhanced by PCBM:P3HT blend. The capacitance–voltage, the conductance–voltage, the series resistances–voltage characteristics of the solar cell were measured in a wide range of frequency for the first time for DSSC applications. The capacitance–voltage shows a behavior from the positive to negative capacitance due to injection of electrons from the FTO electrode into TiO₂. It is evaluated that the photovoltaic performance of the dye-sensitized solar cell can be improved using various organic semiconductors.     

Carriage of Staphylococcus aureus in the nose of patients on regular dialysis treatment using hemodialysis catheters

In the hemodialysis population, the incidence of Staphylococcus aureus colonization has been documented to be as high as 80%; effective prophylaxis of vascular access infection and bacteremia is a worthwhile goal in the management of hemodialysis population. Surveillance of 50 hemodialysis patients for S. aureus‐positive nasal cultures was performed by monthly nasal swabs over a 12‐month period. All patients were performing dialysis using hemodialysis catheters thrice weekly. All positive cultures were treated with a prophylactic antibiotic regimen. Thirty‐one patients (62%) had one or more positive cultures. The surveillance period was longer in the S. aureus nasal carriers (p < 0.01). The frequency of positive cultures correlated with the duration of surveillance (p < 0.05). The incidence of S. aureus bacteremia was greater in patients with three or more positive cultures (p < 0.05). This study suggests that continuous surveillance for S. aureus nasal colonization is essential to properly identify all hemodialysis patients using catheters at risk of developing S. aureus bacteremias.     

Task space decomposition for invariant control of constrained robots

An approach, motivated by analytical mechanics and linear algebra methods, is proposed for task space decomposition. The approach relies on the introduction of a new set of kinematic parameters describing the constrained motion of the end-effector, using the analytical forms of material and program constraints. These parameters define a new basis in the end-effector configuration space. A general inner product characterized by the unity matrix is introduced in this basis and in its dual, which gives rise to the definition of a new set of metrics for the end-effector configuration space. The vectors defined in these bases are considered as pseudo-orthogonal. Returning to the original bases of the configuration space, the symmetric matrices for the vanishing bilinear forms can be defined. In this way, the freedom and constraint subspaces can be defined in a rigorous, analytical way. The physical meaning of the resulting metrics is explained. It is shown that the task space decomposition is invariant, although non-Euclidean metrics are being used. To illustrate the application of the methodology and to explain further the properties of the task space decomposition, two examples are presented. In the first example, the robot end-effector tracks a planar surface. A particular definition of the program constraint gives rise to the introduction of skewed bases, which better explains the inherent features of the approach. In the second example, a task of operating a planar joystick, with constrained orientation of the end-effector, is considered. The relevant bases of the task space are translated in this case and it is possible to explain other features of the method.     

Associations between CD133, CK19 and G2/M in cirrhotic HCV (genotype-4) patients with or without accompanying tumor

Hepatitis C virus (HCV)-cirrhotic patients have the highest threat of developing hepatocellular carcinoma (HCC) and may be at risk of extra hepatic cancer. The present study was designed to investigate CD133 and CK19 in HCV (genotype-4)-cirrhotic patients with/without HCC or extra hepatic cancer, to assess the degree of their correlation with cell cycle abnormalities and finally to assess the role of their combination as diagnostic tool for discrimination of cirrhotic patients with HCC from those with extra hepatic cancer. The study included 77 HCV-cirrhotic patients and 20 healthy non-disease control group. Patients were categorized histo-pathologically into: 24 have only liver cirrhosis, 26 with HCC, and 27 patients with extra hepatic cancer. Cell cycle abnormalities, CD133 and CK19 were determined by flow cytometry technique. CD133 and CK19 showed marked elevation in HCC and extra hepatic cancer compared with liver cirrhosis and control subjects (p<0.0001). Positive associations were noted between CK19, CD133 and G2/M. They were gradually increased with progression from liver cirrhosis to HCC. Combination of the three showed the best AUC (0.978) and accuracy (92.5%) for discrimination of HCC from extra hepatic cancer. Combined CD133 with G2/M and CK19 comprises an excellent diagnostic panel for discrimination of HCV-cirrhotic patients with HCC from those with extra hepatic cancer.     

Stabilization of bio-oil over a low cost dolomite catalyst

A low cost alkaline catalyst of dolomite (CaMg(CO₃)₂) was used to stabilize acacia sawdust bio-oil mixed with methanol. The upgrading efficiency was evaluated in terms of the total acid number (TAN) and viscosity. A change in the dolomite calcination temperature from 700 to 900 °C led to a significant change in the TAN and viscosity of the methanol-added bio-oil. Dolomite activated at higher temperatures had larger amounts of active CaO and MgO species due to the enhanced decarboxylation of calcium and magnesium carbonates. An increase in the dolomite content (1-5 wt%) decreased the TAN value of bio-oil remarkably. A thermal aging test of the methanol-added bio-oil upgraded using dolomite (calcined at 900 °C) at 50 °C for 24 h was carried out by storing the bio-oil at 80 °C for one week. Although the TAN value increased after the aging process, it was still lower than the TAN of raw bio-oil. In addition, increasing the methanol content (10-30 wt%) decreased the TAN and viscosity of the bio-oil significantly.     

Investigation on local and average static hold‐ups in liquid–liquid systems in a rotary disc contactor

A rotating disc contactor with inner diameter of 91 mm and 21 compartments was used to investigate local and average static hold‐ups in the column. Three chemical systems, including distilled water as stagnant continuous phase and toluene, kerosene, and butyl acetate as dispersed phase, in case of no mass transfer, were applied. Different parameters consisting of drop size and static hold‐up were measured experimentally under various operating conditions, and two dimensionless correlations for estimation of local static hold‐up as a function of average mother drop size, physical properties, rotor speed, and stage number were proposed in two cases: (1) immovable and (2) rotating rotor discs. Furthermore, two dimensionless correlations were presented to estimate average static hold‐up as a function of average mother drop size, physical properties, rotor speed, and number of stages in the column in the two aforementioned conditions.