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Effects of species and moisture content on the behaviour of solid wood under impact
Get PDFThe article's main aim is to assess the effects of species and moisture content (MC) on the behaviour of solid wood material under the low velocity of impact and present a pattern for predicting loading vs time curves for these species in different moisture levels. Three groups of samples (300 x 20 x 20 mm) were made from beech, oak, and spruce wood. Each group was subdivided into two groups with low moisture content (LMC) level (10-12%) and high moisture content (HMC) level (40-60%). A drop-weight impact machine did the tests, and high-speed cameras recorded the lateral specimens' surface during the impact. The digital image correlation technique (DIC) determined the strain pattern and the deflection. The timing of the crack initiation was also observed. Also, the force-time charts, the maximum force required for crack initiation, the work needed for crack initiation, and the total work required for the breakage of every specimen were gathered. A general force-time pattern with five identifiable steps was determined for each group. It turned out that the maximum deflection and longitudinal tensile strain of the beams up to crack initiation increase with increased moisture content while maximum force decreases. Unlike beech, the required work for rupture of HMC samples of oak and spruce is higher than LMC group.OA-hybri
How Did COVID-19 Pandemic Stress Affect Poles' Views on the Role of the Forest?
Get PDFThe 2020-2021 COVID-19 pandemic has had a tremendous impact on the daily lives of everyone, including local communities and entire societies. Under the influence of this new experience, the importance of the services and benefits provided by forests and other green spaces has increased. A very large role in this aspect was played by media messages promoting the idea of being close to nature as a remedy for malaise and stress, and pushing the thesis that the risk of spreading the virus outdoors is lower than it is indoors. Thanks to media messages, as well as government responses (i.e., lockdown, temporary bans on entering the forest), public attention has been directed toward forests, generating greater interest in forest management and conservation issues, as well as in nature and forestry education. The purpose of our research was to determine how the pandemic affected the frequency of visits to the forest and how it changed the public's views on the role of forests. The research material consists of the results of a questionnaire survey (online and traditionally way) carried out in Poland from September to October in 2020. A total of 1402 people were surveyed. The results show that nearly 52% of respondents increased their use of forest recreational services during the COVID-19 pandemic. We also found that more than 80% of respondents agreed with statements that the forest is a safer space than, for example, parks or squares, and it is more difficult to contract the virus there. Men were more likely to agree with this statement than women (1.51), respondents without children (1.45), respondents over the age of 31 (1.72), and respondents with more than primary or secondary education (1.37). Also, more than 80% of respondents said that the social functions of the forest (e.g., recreational) had gained importance as a result of the pandemic. The social functions of the forest gained importance primarily among respondents with higher education (2.40), and among respondents who had visited the forest rather infrequently (several times a year) for recreational purposes before the pandemic (1.72). Those with children were more likely to agree with the statement that the economic functions of the forest have lost their importance (1.43), as were those who had formerly visited the forest several times a year (1.53). With regard to the statement "the slowdown of the economy has contributed to the improvement of the environment," there were no statistically significant differences in the views of respondents in terms of their socio-demographic characteristics.O
Proving the automatic benchtop electrochemical station for the development of dopamine and paracetamol sensors
Get PDFThe introduced work represents an implementation of the automatic benchtop electrochemical station (BES) as an effective tool for the possibilities of high-throughput preparation of modified sensor/biosensors, speeding up the development of the analytical method, and automation of the analytical procedure for the determination of paracetamol (PAR) and dopamine (DOP) as target analytes. Within the preparation of gold nanoparticles modified screen-printed carbon electrode (AuNPs-SPCE) by electrodeposition, the deposition potential EDEP, the deposition time tDEP, and the concentration of HAuCl4 were optimized and their influence was monitored on 1 mM [Ru(NH3)6]3+/2+ redox probe and 50 μM DOP. The morphology of the AuNPs-SPCE prepared at various modification conditions was observed by SEM. The analytical performance of the AuNPs-SPCE prepared at different modification conditions was evaluated by a construction of the calibration curves of DOP and PAR. SPCE and AuNPs-SPCE at modification condition providing the best sensitivity to PAR and DOP, were successfully used to determine PAR and DOP in tap water by "spike-recovery" approach. The BES yields better reproducibility of the preparation of AuNPs-SPCE (RSD = 3.0%) in comparison with the case when AuNPs-SPCE was prepared manually by highly skilled laboratory operator (RSD = 7.0%).OA-hybri
Waste sulfur from biogas desulphurization: a supplement of Brassica napus L. nutrition
Get PDFThe content of sulfur in soils has been declining. Possible option to supply sulfur into the soil can be utilization of waste sulfur from biogas production. Two pot experiments with identical treatments were established to examine the effect of waste sulfur from biogas plant applied solely and in mixture with other nutrients on the growth and yield of oilseed rape. The included treatments were control, waste elemental sulfur (S), S + boron (B), S + B + humic substances (HS), S + B + HS + ammonium sulfate (AS), S + B + HS + ammonium nitrate (AN). The results from the first experiment showed significant increase in N-tester values and aboveground biomass after the treatments with S enhanced with both mineral fertilizers compared to any other treatments. The content of N and S in plants was also higher after these treatments. This was confirmed by second experiment. The seed yield was highest after the same treatments. The result from both experiments proved, that reutilization of waste S can be an interesting option. The application of sole waste S is a viable possibility. However, the mixture of sulfur with AS and AN is a more optimal alternative. Such combination could lead to better N use efficiency due to the co-application of N and S and also presents an interesting compromise to an overall lower consumption of mineral fertilizers (especially N) while adding more sulfur to the soil, especially in mixture with AS. This treatment resulted in the highest seed yield and production of oil in comparison with any other treatment.OA-hybri
The interaction between the milk production, milk components with a low frequency of analysis and factors affecting the milk composition in dual-purpose Simmental cows
Get PDFThe aim of this study was to improve the understanding of the contribution of components typically found in milk, but which are not often included in analyses, to the nutritional status of dairy cows. This was undertaken by analysing the amount and composition of milk produced by Simmental dairy cows, a dual-purpose breed farmed in the Czech Republic. Apart from the more frequently analysed group of components in milk, a less frequently analysed group of components were also investigated. This group, typically, consists of the following components: urea, casein, citric acid, beta hydroxy butyrate (BHB) ketones and free fatty acids. The average content of urea, casein and citric acid in milk is 25.75 mg/100 ml, 2.96%, 0.15%, respectively. The influence of environmental factors on these indicators was evaluated, as well as the degree of hereditary establishment. These less frequently analysed components (indicators), as well as the more frequently analysed components of milk, are subject to several external influences, especially the influence of the breeder, the year and the season of calving. The content of these components varied significantly statistically during the lactation period and also in the order of lactation. The influence of a cow's individuality and the degree of additive genetic background are evident, with estimated heritability coefficients ranging from 0.04 for the BHB ketone content to higher values, e.g., 0.28 for citric acid or 0.31 for the lactose content in milk. The relationships between the components of milk and the daily milk yield were also evaluated, and statistically significant negative correlations were found between the content of casein and the daily milk yield (-0.47) and between the lactose content and the number of somatic cells (-0.37).O
A Perspective Review on Green Nanotechnology in Agro-Ecosystems: Opportunities for Sustainable Agricultural Practices & Environmental Remediation
Get PDFThe modern agricultural system is facing the unprecedented task of contriving the extensive demand for agrarian production owing to population explosion and global climate change. The employment of Nanotechnology in agriculture has gained immense interest in recent times for the development of sustainable agricultural technologies and environmental remediation strategies. Nanotechnology pertains to the employment of nanoparticles and furnishes the potential to fabricate novel materials and products possessing improved quality. The nanomaterials may be used as; nanosensors, nanocides, nanofertilizers, nanobarcodes, and nano-remediators, which play a significant role in modern agricultural practices. However, the physical and chemical processes of nanoparticle production is neither economical nor environmentally sustainable. Therefore, the need for green or biogenic nanoparticles obtained from plants, bacteria, fungi or their metabolites has emerged as novel, sustainable, economical, biocompatible, and eco-friendly technology. In this perspective, the production and sources of biogenic nanoparticles and their implication in agro-ecosystems for crop productivity, soil health management, biocontrol, and environmental remediation have been focused on in this review. The potential development and implementation challenges are also explored.O
Properties of lightweight particleboard made with sunflower stalk particles in the core layer
Get PDFIn this study we assessed the efficacy of manufacturing lightweight particleboards using sunflower (Helianthus annuus L.) stalk particles. Three-layer lightweight particleboards with target densities of 350, 450 and 550 kg/m3 were produced with different proportions of wood-to-sunflower stalk particles (100:0%, 75:25%, 50:50%, 25:75%, 0:100%) in the core layer. The outer layers consisted only of wood particles. The boards made entirely with wood particles in the outer and core layers were reference boards. Conventional urea-formaldehyde (UF) resin was used to bond the particles. It was found that the replacement of wood particles in the core layer with sunflower stalk particles led to an improvement in the physical and mechanical properties of lightweight UF-bonded particleboards. Three-layer boards with the optimum combination of 100% wood particles in the outer layers and 100% sunflower stalk particles in the core layer had slightly higher bending strength (MOR) and modulus of elasticity (MOE) than boards made entirely from 100% wood particles, but much greater internal bonding strength (IB), lower water absorption (WA) and less thickness swelling (TS) at the same board density. The MOR, MOE and IB values for 550 kg/m3 boards containing 100% sunflower particles in the core layer were higher than the reference boards by 16.3%, 16.6% and 62.7%, respectively. The MOR, MOE and IB of lightweight particleboards with densities of 450 and 550 kg/m3 made with 100% sunflower particles in the core layer fully complied with the CEN/TS 16368 standard for both types of board, LP1 and LP2. Substitution of wood particles with sunflower stalk particles did not cause negative changes in the formaldehyde content of the boards.Preprin
Performance of 13 crop simulation models and their ensemble for simulating four field crops in Central Europe
Get PDFThe main aim of the current study was to present the abilities of widely used crop models to simulate four different field crops (winter wheat, spring barley, silage maize and winter oilseed rape). The 13 models were tested under Central European conditions represented by three locations in the Czech Republic, selected using temperature and precipitation gradients for the target crops in this region. Based on observed crop phenology and yield from 1991 to 2010, performances of individual models and their ensemble were analyzed. Modelling of anthesis and maturity was generally best simulated by the ensemble median (EnsMED) compared to the ensemble mean and individual models. The yield was better simulated by the best models than estimated by an ensemble. Higher accuracy was achieved for spring crops, with the best results for silage maize, while the lowest accuracy was for winter oilseed rape according to the index of agreement (IA). Based on EnsMED, the root mean square errors (RMSEs) for yield was 1365 kg/ha for winter wheat, 1105 kg/ha for spring barley, 1861 kg/ha for silage maize and 969 kg/ha for winter oilseed rape. The AQUACROP and EPIC models performed best in terms of spread around the line of best fit (RMSE, IA). In some cases, the individual models failed. For crop rotation simulations, only models with reasonable accuracy (i.e. without failures) across all included crops within the target environment should be selected. Application crop models ensemble is one way to increase the accuracy of predictions, but lower variability of ensemble outputs was confirmed.OA-hybri
Monitoring of taurine dietary supplementation effect on parameters of Duroc boar ejaculate in summer season
Get PDFThe aim of this experiment was to find out whether the taurine supplementation in daily ration had an effect on quantity or quality of Duroc boar ejaculate. The experiment duration was from June to August, when it could assumed the possible occurrence of heat stress. For the study was chosen 12 Duroc boars of approximately the same age and condition. The control group of 6 Duroc boars was fed only by basic diet and the experimental group of 6 Duroc boars was fed by the same basic diet with supplementation of 15 g taurine/boar/day. Ejaculate was collected once a week by hand glowed technique. From ejaculate parameters were monitored volume of ejaculate, sperm concentration, total amount of sperm, morphologically abnormal sperm, taurine concentration and GSH/GSSH concentration. From microscopic analysis, results were statistically significant in motility in June and July (P<0.05). In biochemical results, a significant difference (P<0.05) has been found between the experimental groups in the concentrations of taurine as well as GSH/GSSG in ejaculate which indicates the effect of heat stress on boars during the experimental period.O
The links between freedom and the internet in Southeast Asia: a democratic coup or status quo time?
No full textThe last two decades have witnessed a striking increase in the number of Internet users as well as new mechanisms of Internet controls have been introduced in many regimes. The objective of this analysis is to appraise how the growth of online population and Internet controls impact on the state of freedoms and democracy in Southeast Asia. The authors argue that the Internet has maintained its ambiguous role within democracy in the examined region. Four groups of countries were identified in the cluster analysis in accordance with the state of variables in the examined years of 2017 and 2020. The results then stressed that the rising figures of online population had been accompanied by additional restrictions of Internet freedoms. At the same time, the percentage of online population has not proved to be a sufficiently significant variable.Published Versio