Hydroxy Sulfonated Fatty Acid Esters as Surface Active Agents V: Surfactants Containing More Than One Hydrophilic Group

Hydroxy sulfonated fatty acid esters having the general formula RCOOCH₂CHOHCH₂SO₃M (where M is alkali or other metal and R a fatty acid radical) have been synthesized using sulfonated oleic acid, sulfated ricinoleic acid and sulfated-sulfonated ricinoleic acid. Comparative evaluation of their properties have been described and the effect of increasing number of hydrophilic groups and their position in the surfactant molecule discussed.     

Analysis of the effect of resistance increase on the capacity fade of lithium ion batteries

Lithium ion cells, when cycled, exhibit a two‐stage degradation behavior characterized by a first linear stage and a second nonlinear stage where degradation is rapid. The multitude of degradation phenomena occurring in lithium ion batteries complicates the understanding of this two‐stage degradation behavior. In this work, a simple and intuitive model is presented to analyze the coupled effect of resistance growth and the shape of the state of charge (SOC)‐open circuit voltage (OCV) relationship in representing the complete degradation behavior. The model simulations demonstrate that a single resistance that increases linearly on cycling can capture the transition from slow to fast degradation, primarily due to the shape of the SOC‐OCV curve. Further, the model simulations indicate that the shape of the degradation curve depends strongly on the magnitude of current at the end of discharge of the cycling protocol. To verify these observations, specific experiments are designed with minimal capacity loss but with shrinking operating voltage ranges that result in shrinking operating OCV range. The results of the experiments validate the observations of model simulations. Further, long‐term cycling experiment with a commercial lithium ion cell shows that the operating OCV range shrinks substantially with aging and is a major reason for the observed accelerated degradation. The analysis of the present work provides significant insights towards developing simple semiempirical models suitable for battery life management in microcontrollers.     

Photocatalytic water oxidation at bismuth vanadate thin film electrodes grown by direct liquid injection chemical vapor deposition method

Photoelectrochemical cells (PECs) are devices that can harvest and convert solar energy to produce consumable fuel, e.g. by splitting water into oxygen and hydrogen. Photocatalytic semiconductor materials play a major role in PECs, and their overall efficiency is usually limited by short carrier diffusion length because of structural defects, poor light absorptivity, and sluggish kinetics of photoelectrochemical reactions at the semiconductor electrode. Synthesis of high quality defect-free semiconductor materials using high temperature deposition techniques generally yield films with good adhesion to substrates while improving charge carrier transport and hence the overall efficiency of a PEC. A direct liquid injection chemical vapor deposition (DLI-CVD) technique has been utilized to synthesize monoclinic clinobisvanite phase bismuth vanadate (BiVO₄) films for photocatalytic water oxidation. The technique yields dense high quality epitaxial and polycrystalline BiVO₄ films on Yttria stabilized zirconia (YSZ) and Fluorine doped tin oxide (FTO) substrates, respectively, at growth temperature in the range of 500–550 °C. The photoelectrochemical characteristics of the films grown on FTO have been studied and a photocurrent value of 2.1 mA/cm² at 1.23 V vs Normal hydrogen electrode (NHE) (0.5 V vs. Ag/AgCl), with onset potential values as low as 0.23 V vs. NHE (?0.5 V vs. Ag/AgCl), are obtained despite the low porosity of the films. The PEC performance is further improved by synthesizing BiVO₄ directly on top of a tungsten oxide interlayer and modifying its surface with FeOOH co-catalyst.     

New Mechanistic Insights in the Cytochrome P-450 Model Reactions: Direct Identification of the Reactive Intermediates

In CH₃CN–H₂0 medium the porphyrin Fe(IV)=O and porphyrin-C₆F₅IO adduct, and tBu $\dot{\hbox{O}}$ /tBuO $\dot{\hbox{O}}$ radicals have been spectroscopically identified. The involvement of multiple reactive intermediates in C₆F₅IO oxidizing system has also been demonstrated.     

Integration of Image Matching and Classification for Multimedia Navigation

With the recent explosive growth in the volume of images on the World-Wide Web, it has become increasingly difficult to search for images of interests. The classification of images helps users to access a large image collection efficiently. Classification reduces search space by filtering out unrelated images. Classification also allows for more user-friendly interfaces: users can better visualize easily result space by browsing the representative images of the candidates. In this paper, we present a technique for image classification based on color, shape and composition using the primary objects. We apply this classification technique in image matching for image retrieval on the Web. Our experimental results show that this approach can maintain 73% of recall by searching only 24% of the whole data set. We also show how we apply such technique to assist users in navigation.     

Polymer blends, 3. Preparation and evaluation of the blends of shellac with polyamideimide from rosin

Polymer blends were prepared from shellac and polyamideimide. The polyamideimide was synthesized by reacting rosin maleic anhydride Diels-Alder adduct with 4,4′-diamino diphenylmethane. The compatibility of these blends was studied by solubility parameter, heat of mixing data, solution viscosity, and differential scanning calorimetry. It was found that the composition of 40 : 60, shellac : polyamideimide produces a compatible blend. The thermal behaviour of the blends was investigated.     

Isocyanate-modified dehydrated castor oil

Esters of dehydrated castor oil fatty acids with polyhydric alcohols like ethylene glycol, propylene glycol, glycerol, pentaerythritol and sorbitol have been prepared. The esters, having hydroxyl value ranging from 78.5 to 167, were reacted with toluene diisocyanate. The scratch hardness and other film properties of the resulting urethanes have been studied. Urethanes obtained from various mixtures of the above esters also have been studied. The best results have been obtained when a mixture of ethylene glycol ester and plenaerythritol ester of dehydrated castor oil fatty acids in the ratio of 4:1 are reacted with one equivalent of toluene diisocyanate. One equivalent of glycerol ester (hydroxyl value 78.5), ethylene glycol ester (hydroxyl value 167), or propylene glycol ester (hydroxyl value 159.4) of DCO fatty acids when reacted with 1.25 equivalent of toluene diisocyanate also gave satisfactory products.     

Stability evaluation of dump slope using artificial neural network and multiple regression

The present study mainly investigates the effect of the residual surface stress and the applied electric voltage on the nonlinear dynamic instability of the viscoelastic piezoelectric nanoresonators under parametric excitation. In fact, great attention is given to the influence of the residual surface stress on the nonlinear instability of the system. Numerical examples are treated which show various bifurcations. By means of a bifurcation analysis, it is shown that the instability of the system can be significantly affected by considering the residual surface effect. The results also show that a discontinuous bifurcation is always accompanied by a jump. Finally, stable and unstable regions in dynamic instability of viscoelastic piezoelectric nanoplates are addressed.