No abstract

The use of solar panels in low-power applications is an increasingly developing topic. Various methods are currently used to obtain the highest possible solar panel power generation efficiency. The methods of determining the maximum power point (MPP) and its tracking are under constant development, resulting in the creation of new algorithms to accelerate the operational efficiency while maintaining good parameters. Typically, these methods are only used in high-power photovoltaic installations. Due to the problems resulting from the adjustment to MPP working conditions for low-power solar panels used to charge a Li-Ion battery, an attempt was made to check the feasibility of operating control based on a Pulse Width Modulation (PWM) method and a Maximum Power Point Tracking (MPPT) algorithm like the one used in high-power solar systems also for low-power systems. The article presents adaptation of PWM and MPPT methods for small chargers, including the stages of modelling a solar charger and the results of a computer simulation of the charger operation. The stages of building a real, physical device are also presented. From the analysis of the test results of the constructed charger in real- and laboratory conditions with the use of a device imitating sunlight, the so-called solar box, and comparisons with computer simulations show that the assumed goal was achieved. The results obtained with the PWM method were compared with the MPPT method. The optimization of the device operation parameters and improvement of the algorithms used in the MPPT method resulted in better optimalization of maximum point tracking, improving the efficiency of energy storage from solar cells.

The formation of strobili, which are groups of sporangia-bearing sporophylls on shoot apices, terminates the axis growth in the majority of lycopods. Here, we present an interesting developmental aberration in Lycopodium annotinum. The structure of abnormal strobili was histologically analyzed using the anatomical sections. Additionally, the expression patterns of LAMB1 and LAMB2, which are known to be specific to Lycopodium annotinum sporogenous and vegetative tissues, respectively, were comparatively analyzed in normal and abnormal strobili. Histological analyses revealed that the morphological and anatomical changes in abnormal strobili were related to the resumption of the vegetative growth of the strobilus apex after the production of several sporophylls and sporangia. The identity of both distinct zones of abnormal strobili, i.e., the basal sporangial part and the apical proliferative part, was confirmed by expression patterns of LAMB1 and LAMB2, indicating that microphylls in the apical proliferative zone were of the vegetative type. The results strongly suggest a change of meristem fate and activity in the process of abnormal strobilus formation. The abnormal strobili in L. annotinum could be a specific example of reversion in lower vascular plants. This phenomenon in lycopods is discussed in a developmental context.

A transgenic winter triticale line expressing the uidA gene, encoding β-glucuronidase, was used to assess the pollen flow in field experiments over two consecutive vegetation seasons in central Poland. The experimental design included two variants of mixed transgenic and non-transgenic lines. Pollen grains were collected using passive traps located at 0, 10, 30, 60 and 85 meters from the transgenic line. GM pollen grains were detected histochemically by staining with x-Gluc. A positive effect of temperature increase, as well as the strength and direction of the wind on the number and spread of pollen grains was observed. Regardless of the experiment year and variant, only few pollen grains were observed at a distance of 85 m. In the first year of the study the amount of pollen grains at 85 m was 300-fold lower than at the source and 140-fold lower in the second year. The number of transgenic pollen grains was two times lower when the field with the transgenic triticale was surrounded by a non-transgenic line, compared to an empty field. On the basis of the obtained results, we suggest 100 m as the distance for triticale pollen migration, although longer flight incidents are possible in extreme atmospheric conditions.

While each individual root responds to such environmental factors as light or gravity the question arises how these reactions subordinate to the whole root system, which is supposed to maintain its primary functions. Data presented here confirm that in cucumber the gravity and light modulate the growth direction of the lateral roots subunits of the system. Another important factor affecting behavior of lateral roots is an orientation of the main root. These facts all together suggest that the root system functions as an integrated entity, capable of adapting its architecture to changing environmental conditions. Its flexibility, based on unknown signaling network, guarantees optimal functioning of the system