Donor–acceptor interaction between non-aqueous solvents and I2 to generate I3, and its implication in dye sensitized solar cells

The spectrophotometric properties of I⁻, I₂ and the I⁻/I₂ mixture were studied in 1,2-dichloroethane (DCE), acetone (AC), acetonitrile (ACN), ethanol (EtOH), methanol (MeOH), tertiary-butanol (t-BuOH), dimethylformamide (DMF), propylenecarbonate (PC), 3-methoxypropionitrile (MePN), dimethylsulfoxide (DMSO), dioxane (DIO) and pyridine (PY) solutions. From the investigation it has been realized that in DCE, I⁻, I₂ and I⁻/I₂ mixture have the same absorption peak at 500 nm. I⁻ gives rise to the absorption spectra at about 220, 290 and 360 nm in t-BuOH and in PY solutions. However, in all other solvents the I⁻ generates peaks only around 220 nm. Similarly I₂ and the I⁻/I₂ mixture in all solvents except DCE have indicated similar absorption peaks around 220, 290 and 360 nm. On the other hand, except in PC and DMF, I₂ shows the additional peaks in the range of 380–500 nm which are assigned to the formation of a I₂–solvent complex. The peaks around 290 and 360 nm indicate the presence of I⁻₃ and around 220 nm is the peak of I⁻. The spectral shift of the I₂ solutions in the visible region is interesting and is the core of this report. It points to the importance of donor–acceptor interaction between solvents and iodine. The data obtained in these solvents were well correlated to the donor number (DN) of the solvents. From this correlation the DN of MePN was estimated to 14.6. The absorption peak of I₂ in DCE(DN=0.0) is 500 nm and in PY(DN=33.1) is 378 nm. This peak shift due to solvent effects corresponds to an energy difference close to 0.8 eV. The absorption peak shift due to addition of the 0.0080 vol%. PY(1 mM) in 1 mM I₂-ACN solutions corresponds to ca. 0.6 eV. The blue shift of I₂ absorption in basic solvents indicates the tendency to form a complex. The increase of the efficiency of the dye-sensitized solar cell by addition of PY to I⁻/I⁻₃ ACN solution is suggested to be due to the formation of the dipyridine complex, PY₂I⁺. Such complex formation decreases the amount of I₂ which is expected to be an electron scavenger. We also propose that the more bulky complex, PY₂I⁺ has a slower kinetics with the conduction band electrons, and thus decrease the losses of photocurrent and photopotentials in the solar cell.     

Evaluation of wet corn gluten feed in diets for lactating dairy cows.

Two experiments were conducted to evaluate responses of primiparous and multiparous Holstein cows to diets containing wet corn gluten feed (WCGF). In both experiments, WCGF replaced a mix of alfalfa hay, corn silage, and corn grain. In experiment 1, 32 primiparous Holstein cows (four pens with eight cows/pen) were used in two 2 x 2 Latin squares with 28-d periods. Cows were housed in free stalls and fed diets containing 0 or 20% WCGF dry matter (DM) basis. Cows fed WCGF consumed more DM and produced more energy-corrected milk (ECM) than controls. Production efficiency (ECM/DM intake) was not affected, but yield of milk components was improved by WCGF. In experiment 2, 24 multiparous Holstein cows were used in six 4 x 4 Latin squares with 28-d periods to determine the optimal dietary inclusion rate for WCGF. Cows were housed in a tie-stall barn and fed a total mixed ration twice daily. Treatments were 0, 20, 27.5, and 35% WCGF (DM basis). Cows fed WCGF produced more ECM than controls, but ECM did not differ among cows fed WCGF diets. Cows fed 20 and 27.5% WCGF consumed more DM as a percentage of body weight than those fed either 0 or 35% WCGF. Cows fed WCGF produced ECM more efficiently than controls. Percent milk fat was lower, but fat yield was not different when WCGF was added to diets. Milk protein and lactose yields were higher when WCGF was fed. Plasma glucose, alpha-amino N, and triglyceride concentrations were similar among diets in both experiments, but plasma urea N was higher for cows fed WCGF in experiment 2.     

Transformation-toughening in cemented carbides: Part II. Thermomechanical treatments

WC-(Fe, Ni, C) cemented carbides can be successfully transformation-toughened by careful control of binder composition and taking into consideration the effect of thermal residual stress on the transformation characteristics of the binder. An additional degree of control on the metastability of the binder phase can be achievedvia thermomechanical treatments. These treatments consist of transforming an austenitic binder to martensite by cooling in liquid nitrogen followed by a suitable high temperature heat treatment to reaustenitize it. Thein situ deformation of the binder caused by the large shape and volume changes that accompany its transformation to martensite thus provides the mechanical component of the thermomechanical treatment. Subsequent heat treatments not only reaustenitize the binder but also modify its susceptibility to undergo stress-induced transformation. It is shown that the hardness/fracture toughness behavior of WC-(Fe, Ni, C) cemented carbides can be significantly improved by the application of such treatments. A qualitative explanation for the enhancements in fracture toughness provided by thermomechanical treatments is offered based on a careful examination of the changes in phase constitution of the binder that occur during these treatments. Formerly Manager, Research-Development, Reed Tool Company, Houston, TX.     

Language and the perception of emotion.

Three studies assessed the relationship between language and the perception of emotion. The authors predicted and found that the accessibility of emotion words influenced participants' speed or accuracy in perceiving facial behaviors depicting emotion. Specifically, emotion words were either primed or temporarily made less accessible using a semantic satiation procedure. In Studies 1 and 2, participants were slower to categorize facial behaviors depicting emotion (i.e., a face depicting anger) after an emotion word (e.g., "anger") was satiated. In Study 3, participants were less accurate to categorize facial behaviors depicting emotion after an emotion word was satiated. The implications of these findings for a linguistically relative view of emotion perception are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Optical switching by a dielectric-cladded nematic firm

An analysis and experimental results on optical switching from a transmission to a total reflection state, using a nematic film bounded by two prisms, are presented. This configuration provides a useful scheme for optical limiting applications with a large dynamic range. From the preliminary experiments and an analysis based on the nonlinear Fabry-Perot effect given elsewhere it is clear that this type of device can be optimized to meet practical self-limiting device applications     

Predictability and unpredictability in Kalman filtering

The authors study the dynamical behavior of the Kalman filter when the given parameters are allowed to vary in a way which does not necessarily correspond to an underlying stochastic system. This may correspond to situations in which the basic parameters are chosen incorrectly through estimates. The authors show that, as has been suggested by Kalman, the filter equations converge to a limit (corresponding to a steady-state filter) for a subset of the parameter space which is much larger than that corresponding to bona fide stochastic systems. More surprisingly, in the complement of this subset, the filtering equations behave in both a regular and an unpredictable manner, representative of some of the basic aspects of chaotic dynamics. This interesting dynamical behavior occurs already for one-dimensional filters, and a complete phase portrait in this case is given