CONCENTRATIONS OF THE MAIN NUTRIENTS (N, P, K, B, ZN) IN FLAX SEED, STEMS AND CHAFF

During 1996-1998 experiments were carried out at the Lithuanian Institute of Agriculture’s Upyte Research Station to measure the contents of the main nutrients (N, P, K, B, Zn) accumulated in flax plants (seeds, stems and chaff) at harvesting on the following backgrounds: not fertilized, fertilized with P20 and N15P20K60; applied with ZnSO4 at the rates from 0,35 to 4,0 kg ha-1. It was determined that fibre flax seeds accumulated 3.30–4.06 % of N, 0.55–0.78 % of P, 0.69–1.15 % of K, 39.5–68.5 mg kg-1 of Zn, 10.00–27.00 mg kg-1 of B, the stems – 0.32–0.88 % of N, 0.04–0.15 % of P, 0.38–1.45 % of K, 5.0–18.0 mg kg-1 of Zn, 5.16–30.84 mg kg-1 of B, the chaff – 0.94–2.34 % of N, 0.20–0.38 % of P, 0.18– 1.40 % of K, 14.5–57.0 mg kg-1 of Zn, 8.55–38.19 mg kg-1 of B. The obtained data could be used for calculating the amount of main nutrients removed from the soil with flax yield as well as for fixing fertilizer rates more precisely

Carrier Tunneling from Charge Transfer States in Organic Photovoltaic Cells

Charge transfer (CT) states play a key role in the functioning of organic solar cells; however, understanding the mechanism by which CT states dissociate efficiently into free charges remain a conceptual challenge. Here, the electric field dependent dynamics of charge generation in planar cyanine/fullerene photovoltaic cells is probed over a wide temperature range using time-resolved Stark effect experiments, transient absorption, and photocurrent measurements. Results indicate that dissociation of thermalized CT states is the rate-limiting step for all temperatures. The dissociation rate strongly depends on the field, but is temperature independent. The results also suggest that the yield of generated charges is temperature independent. Model electrostatic calculations illustrate that specific orientations of the cyanine crystal relative to C60 create a repulsive potential for an electron near the interface that is largely due to the quadrupole moment of the unit cell. In combination with the electron-hole coulomb attraction and the electric field-induced barrier lowering, a high-energy potential barrier forms with a narrow width of a few nanometers. It is proposed that charge separation occurs via a field-dependent electron tunneling mechanism through that barrier, which is temperature independent. The results support a thus far overlooked pathway for CT state dissociation via carrier tunneling