A Circle Has No End: Role of Cyclic Topology and Accompanying Structural Reorganization on the Hole Distribution in Cyclic and Linear Poly‑p‑phenylene Molecular Wires

π-Conjugated organic oligomers/polymers hold great promise as long-range charge-transfer materials for modern photovoltaic applications. However, a set of criteria for the rational design of functional materials is not yet available, in part because of a lack of understanding of charge distribution in extended π-conjugated systems of different topologies, and concomitant effects on redox and optical properties. Herein we demonstrate the role of cyclic versus linear topology in controlling the redox/optical properties and hole distribution in poly-p-phenylenes (PPs) with the aid of experiment, computation, and our recently developed multistate parabolic model (MPM). It is unequivocally shown that the hole distribution in both cyclic and linear poly-p-phenylene (n ≥ 7) cation radicals is limited to seven p-phenylene units, despite the very different topologies. However, the effect of topology is evidenced in the very different trends in oxidation potentials of cyclic versus linear PPs, which are shown to originate largely from the geometrical distortion of individual p-phenylene units in cyclic PPs. The presence of additional pairwise electronic coupling element in cyclic PPs, absent in linear PPs, plays a significant role only in smaller cyclic PP5 and PP6. This study provides a detailed conceptual description of cyclic and linear poly-p-phenylene cation radicals and demonstrates the versatility and predictive power of MPM, an important new tool for the design and synthesis of novel and efficient charge-transfer materials for molecular electronics and photovoltaic applications, an area of widespread interest

NEW GENERATION CO-OPERATIVES (NGC) AS A MODEL FOR VALUE-ADDED AGRICULTURAL PROCESSING IN ALBERTA: APPLICATIONS TO FACTORS AFFECTING CHOICE OF PRICING AND PAYMENT PRACTICES BY TRADITIONAL MARKETING AND NEW GENERATION CO-OPERATIVES

This study examines the factors affecting choice of pricing and payment practices by traditional marketing and new generation co-operatives for commodities delivered by their members. These factors include the demographic variables related to type of co-operative organization, level of competition in commodity market, and risk-return perceptions of members and co-operatives. Data for the analysis were obtained through a mail survey. Questionnaires were send to one hundred and ninety five (195) co-operatives in mid-west states of the U.S.A. and Canada. Altogether 93 co-operatives responded to the survey. Mean score analysis, factor analysis and multinomial logit analysis were done. The results indicate that traditional marketing co-operatives are more likely to choose spot market cash price, while new generation co-operatives are more likely to choose pooling practices. Traditional marketing co-operatives appear to be concerned about the members' cash flow needs and members' uncertainty of return; they are also more responsive to increased competitive level in commodity market. New generation co-operatives are more concerned with avoiding the risk of co-operatives' operating deficits and survival of co-operatives. This has implications for new co-operatives just beginning in business.Agribusiness,

Atomic Compton profiles within different exchange-only theories

The Impulse Compton Profiles (CP's) J(q) and the - expectation values for some inert gas atoms (He-Kr) are computed and compared within the Harbola-Sahni (HS), Hartree-Fock(HF) theories and a Self Interaction Corrected (SIC) density functional model. The Compton profiles for excited states of Helium atom are also calculated. While the calculated CP's are found to generally agree, they differ slightly from one another for small values of the Compton parameter q and are in good agreement for large q values. The expectation values within the three theories are also found to be comparable. The HS formalism seem to mimic HF reasonably well in the momentum space, establishing the logical consistency of the former.Comment: 15 page

Field Screening of Lentil Genotypes Against Aphid Infestation in Inner Tarai of Nepal

Twenty lentil (Lens culinaris Medik) genotypes received from Grain Legumes Research Program, Khajura, Banke were screened for relative tolerance against aphid (Aphis craccivora Koch.) at the research field of National Maize Research Program, Rampur, Chitwan during winter seasons of two consecutive years 2016 and 2017. The design of the experiment was Randomized Complete Block having three replications. The unit plot size was 4m × 1 m with 25cm row to row spacing and continue plant to plant spacing was maintained and net harvested plot was 4 square meters. The recommended dose of fertilizer was 20:40:20 N:P2O5:K2O kg/ha and seed rate 30 kg/ha. Insect data were collected based on aphid population found at apical twigs (10 cm) per plant and scoring was done during flowering and pod formation stage. The grain yield was recorded. All screened genotypes differed significantly (p<0.05) on aphid population and grain yield.  Genotypes, ILL 9924, RL 83, ILL 10856, ILL 6458 and RL 67 were less susceptible with higher grain yield. These results have important implications for the development of aphid tolerant high yielding lentil variety in inner Tarai of Nepal

Non-linear dynamic analysis of geared systems, part 2

A good understanding of the steady state dynamic behavior of a geared system is required in order to design reliable and quiet transmissions. This study focuses on a system containing a spur gear pair with backlash and periodically time-varying mesh stiffness, and rolling element bearings with clearance type non-linearities. A dynamic finite element model of the linear time-invariant (LTI) system is developed. Effects of several system parameters, such as torsional and transverse flexibilities of the shafts and prime mover/load inertias, on free and force vibration characteristics are investigated. Several reduced order LTI models are developed and validated by comparing their eigen solution with the finite element model results. Several key system parameters such as mean load and damping ratio are identified and their effects on the non-linear frequency response are evaluated quantitatively. Other fundamental issues such as the dynamic coupling between non-linear modes, dynamic interactions between component non-linearities and time-varying mesh stiffness, and the existence of subharmonic and chaotic solutions including routes to chaos have also been examined in depth