Pharmaceutical electrochemistry: the electrochemical detection of aspirin utilising screen printed graphene electrodes as sensors platforms.

A sensitive electrochemical sensor was designed for acetyl salicylic acid detection using graphene modified Screen Printed Electrodes. The electrochemical response of the sensor with graphene was improved compared to Screen Printed Electrodes without graphene and displayed an excellent analytical performance for the detection of acetyl salicylic acid. The high acetyl salicylic acid loading capacity on the electrode surface and the outstanding electric conductivity of graphene were also discussed in this manuscript. When a range of different concentrations of acetyl salicylic acid from 0.1 to 100 μM into a pH 4 buffer solution (N defined as the sample size N = 9) were plotted against the oxidation peak a linear response was observed. The detection limit was found to be 0.09 μM based on (3-σ/slope). Screen Printed Graphene electrodes sensors methodology is shown to be useful for quantifying low levels of acetyl salicylic acid in a buffer solution as well as in biological matrixes such as human oral fluid. A linear response was obtained over a range of concentrations from 10 to 150 μM into a human oral fluid solution (N = 10) giving a detection limit of 8.7 μM

Dynamic Changes in the Spatiotemporal Localization of Rab21 in Live RAW264 Cells during Macropinocytosis

Rab21, a member of the Rab GTPase family, is known to be involved in membrane trafficking, but its implication in macropinocytosis is unclear. We analyzed the spatiotemporal localization of Rab21 in M-CSF-stimulated RAW264 macrophages by the live-cell imaging of fluorescent protein-fused Rab21. It was demonstrated that wild-type Rab21 was transiently associated with macropinosomes. Rab21 was recruited to the macropinosomes after a decrease in PI(4,5)P2 and PI(3,4,5)P3 levels. Although Rab21 was largely colocalized with Rab5, the recruitment of Rab21 to the macropinosomes lagged a minute behind that of Rab5, and preceded that of Rab7. Then, Rab21 was dissociated from the macropinosomes prior to the accumulation of Lamp1, a late endosomal/lysosomal marker. Our analysis of Rab21 mutants revealed that the GTP-bound mutant, Rab21-Q78L, was recruited to the macropinosomes, similarly to wild-type Rab21. However, the GDP-bound mutant, Rab21-T33N, did not localize on the formed macropinosomes, suggesting that the binding of GTP to Rab21 is required for the proper recruitment of Rab21 onto the macropinosomes. However, neither mutation of Rab21 significantly affected the rate of macropinosome formation. These data indicate that Rab21 is a transient component of early and intermediate stages of macropinocytosis, and probably functions in macropinosome maturation before fusing with lysosomal compartments

Preparation and characterization of Poly(vinylidenefluoride)-CdSiO3 nanocomposite thin films

The state of art behavior of PVDF-CdSiO3 nano-composite has been reported in context to their crystal structure, morphology and optical bandgap. Nanocomposites of varying concentration (1, 3 and 5 wt %) were prepared by spin coating method. The thickness of the film was measured by using Elecro Physik instrument and was found to be ~40µm. Peaks in the X-ray diffraction pattern indicate the presence of CdSiO3 nanoparticles in PVDF matrices and absence of any extra peak in the pattern shows that there is no new phase formation. The scanning electron microscope (SEM) images showed that nano inclusions are uniformly distributed in PVDF matrix. It is also observed that the granular structure PVDF disappears with the increase in the concentration of CdSiO3. The shift in the optical edges as observed by UV-Vis spectra of the developed composites has been correlated to optical band gap using Tauc’s expression. The composite showed an increasing trend in the optical band gap from 3.6eV to 5.2eV with the increase in the concentration of the nanofillers. The present study finds potential applications in the design of microsensors and actuator

Some properties of indium-tin oxide-films

Thin films of indium-tin oxide have been deposited by DC diode sputtering from an indium-tin alloy target in an argon, hydrogen and oxygen atmosphere. Films with sheet resistance of 11 ohms/square and 80% light transmission have been obtained. The effect of cathode composition and gas mixture on sheet resistance and optical transmission properties of the films have been studied

Characterization of Al2O3Al_2O_3 thin films prepared by spray pyrolysis method for humidity sensor

$Al_2O_3$ thin films were deposited on silicon, steel and nickel substrates to fabricate MOS and MIM devices. The films were prepared by spray pyrolysis method using a spray solution of Aluminium acetyl acetonate dissolved in dimethyl formamide and this solution was sprayed on to the hot substrates at temperatures of 300 and $350^oC$. The films were amorphous in nature as detected by XRD. Capacitance versus voltage (C–V), current versus voltage (I–V) and capacitance versus frequency (C–f) measurements were taken for these films. MOS capacitor was used as a humidity sensor using the home made humidity sensor setup. ac capacitance and parallel resistance of the capacitor as a function of humidity were studied. It was found that the capacitance value increases from 0.537 to 2.073 nf with the increase in relative humidity (RH) from 0 to 90% and the resistance decreases from 153 to 93 $k\Omega$ with the increase in relative humidity from 20 to 87%. Relative dielectric constant versus temperature measurements were done for the MOS device to check its ferroelectric behavior and its critical temperature was found to be around $66^oC$. MIM device was also used as a humidity sensor by measuring capacitance as a function of time by keeping the sensor in a dessicator. The 555 timer circuits were used to check the sensor behavior of the MOS device. Volume resistivity and breakdown electric field of the film deposited on steel were measured and found to be $5\times10^{11} \Omega \hspace{2mm} cm \hspace{2mm} and\hspace{2mm} 5\hspace{2mm} MV/cm$, respectively

A new, extinct pleistocene reef coral from the Montastraea ‘‘Annularis’’ species complex

A new species of the Montastraea "annularis" species complex is herein described from Pleistocene coral reefs of the Caribbean Sea. The species, Montastraea nancyi n. sp., had a broad geographic distribution at mainly insular sites 125 Ka. It has a fossil record extending from >600 Ka (thousand years) to 82 Ka, both first and last occurrences exclusively on the island of Barbados. It also had a broad environmental tolerance, occurring in fringing, windward back-reef and reef-crest, leeward reef-crest, and lagoonal patch-reef environments. In every habitat in which it lived, there are examples that it either dominated the coral fauna or shared dominance with Acropora palmata, a dominant shallow water coral in high-energy Pleistocene and modem reefs. The extinction of Montastraea nancyi resulted in evolutionary and ecological change in surviving members of the M. "annularis" species complex