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Innovative fibreboard from wet-preserved hemp
2013
Kirilovs, E., Riga Technical Univ. (Latvia) | Gusovius, H.-J., Leibniz Inst. for Agricultural Engineering Potsdam-Bornim, Potsdam (Germany) | Dolacis, J., Latvian State Inst. of Wood Chemistry, Riga (Latvia) | Kukle, S., Riga Technical Univ. (Latvia)
The growing popularity of wooden panels renders this market segment increasingly competitive. The article describes a new type of fibre boards e.g. the furniture production, developed in cooperation with ATB (Leibniz-Institute for Agricultural Engineering Potsdam-Bornim) by using a new method of raw material preparation and specific production technologies of ATB. The main raw material is preserved hemp (Cannabis sativa) stalks. The samples are made of raw materials with different wet-preservation time and varying types of binder. For the first time there is used main raw material with short time wet-preservation. Samples that are 8 mm thick correspond to a medium-density fibreboard and that are 16mm thick correspond to a low-density fibreboard, fitting in its mechanical properties to standard BS EN622. On ATB’s experimental processing line 1,200x800x8 mm and 1,200x800x16 mm size board samples are produced and the tests are performed to determine such parameters as bending strength, thickness swelling and thermal conductivity according to EU standard methods.
Показать больше [+] Меньше [-]Effect of high pressure processing on microbial load in pork
2017
Sazonova, S., Latvia Univ. of Agriculture, Jelgava (Latvia) | Galoburda, R., Latvia Univ. of Agriculture, Jelgava (Latvia) | Gramatina, I., Latvia Univ. of Agriculture, Jelgava (Latvia)
Fresh meat is a highly perishable product due to its biological composition as it serves as an ideal environment for the growth and propagation of microorganisms and common food-borne pathogens. High pressure processing (HPP) is a cold pasteurization treatment to extend shelf-life while preserving the sensory and nutritional characteristics of the product. The aim of this research was to evaluate the effects of HPP on the fresh porcine Musculus longissimus lumborum microbial load and related physical properties (pH, water activity aw, and moisture content). Vacuum packed meat samples were treated at 50, 100, 200, 300, 400, and 500 MPa for 1, 5, and 15 min in a high-pressure processor ISO-Lab S-FL-100-250-09-W (Stansted Fluid Power Ltd., UK). Pressure treatment above 300 MPa resulted in a significant (p is less than 0.05) decrease of total plate count. However, the studied pressurizing time had no significant effect on microbial lethality at the same pressure applied. Other important parameters such as water activity, moisture, and pH were determined as they directly affect microorganism growth and resistance to pressure. A slight increase in pork pH was observed with increased pressure. No significant changes in water activity and moisture content were observed as a result of high pressure treatment. For future researches it would be important to evaluate the dynamics of microbial growth during storing as part of cells after pressure treatment are injured and not eliminated immediately; therefore, microbial count may further decrease during cold storage.
Показать больше [+] Меньше [-]Duration of load effects on development of deformations in bolted moment connection
2020
Fabriciuss, J., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Ozola, L., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia)
Experience saved in the construction industry shows that the timber portal frames with semi-rigid connections at knee joint exhibit permanently increase displacements at the knee and apex point. Normally, timber portal frame with semi-rigid knee joint connection is made with mechanical fasteners located in double circles and cannot be designed without relevant rotation at connection during structures’ exploitation time. The only way to increase connection rigidity is to rise distance from fasteners location at connection, but at the same time, the tension and shear stress become significant at the external section of members. The previous experience is obtained by a model testing showing that deformations at semi-rigid connections are non-linear. These were tests under short-term load and did not disclose creep effects, which can be significant. This study is aimed at the examination of increasing deformations with time under constant static load (creep effects) in semi-rigid dowelled connection. Experimental test models were made and set under long-term load in controlled environmental conditions (heated laboratory room). Results show a significant creep influence to decrease connection stiffness. Corresponding numerical test of orthotropic 3d model by Dlubal RFEM software tools was performed analysing the value of expected deformations. Results of the numerical test showed that friction between timber elements and extra nuts on bolts can increase connection stiffness. Research results in this stage show that the creep can affect connection stiffness more than expected. Also, experimental test results showed lower deformation values comparing with the ones obtained by the numerical test.
Показать больше [+] Меньше [-]High pressure effect on the sensory and physical attributes of pork
2018
Sazonova, S., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Galoburda, R., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia)) | Gramatina, I., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Straumite, E., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia)
High-pressure processing (HPP) is typically used for the microorganism inactivation, which provides safety and prolonged shelf life of meat and meat products. However, for consumers along with safety, it is important to have good sensory properties, which is a combination of tender and juicy meat with an intense meat flavour. These attributes may change because of the high pressure processing; therefore, the aim of the study was to evaluate the effect of HPP on sensory and physical attributes of pork upon processing at 300 and 600 MPa at room temperature for 1 and 15 min. After HPP the processed pork samples were cooked within the package in a water bath. Colour of cooked pork did not differ among samples. Moisture content of samples decreased with the increased processing time. Sensory evaluation revealed that HPP treatment did not influence the colour and flavour of cooked pork irrespective of treatment parameters applied in the current study. The panellists indicated that increased pressure made pork samples drier and tougher, thus changing such sensory attributes as juiciness and chewiness, which are important for meat palatability. The correlation found between chewiness determined by sensory analysis and toughness determined by Warner-Bratzler shear device suggested this instrumental method as a better tool when compared to the instrumental texture profile analysis (TPA).
Показать больше [+] Меньше [-]Evaluation of compliance of existing forest machine information systems for the implementation of the standard StanForD 2010
2020
Strubergs, A., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Lazdins, A., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Sisenis, L., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia)
The aim of the study is to clarify the compliance of machinery information systems used by Latvian logging service providers with the requirements of the Forest Machine Data and Communications Standard StanForD 2010. For determining the number of logging machines and structure registered in Latvia, data from the State Technical Control Agency of Latvia (VTUA) has been used. This dataset includes 2094 registered machinery units from which 1663 units recorded as harvesters and forwarders are distributed for data processing. Using the national AS Latvian State Forests (LSF) database, where 541 machinery units have been recorded, of which 239 harvesters and 302 forwarders, it is determined what and how many machines already use the standard StanForD 2010, how many machines can implement it and which machines are not suitable for the implementation of StanForD 2010. The study showed that the VTUA register does not fully reflect the true quantity of harvesting machines in Latvia and does not provide information about the use of machines. The LSF data provide reliable information on the possibilities of using StanForD 2010 in harvesters in national forests. From the harvesters working in the country’s forests, 52% of the machines use the StanForD 2010 standard. Work should be continued to clarify the possible use of the standard in the machines working in private forests. Similarly, work should be continued with dealers of harvesting machines to identify models for which it is possible to adjust the StanForD 2010 standard and what the cost of adapting the indicative information systems is.
Показать больше [+] Меньше [-]A survey of statistics of building fires in Latvia
2020
Grants, E., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia)
A survey of 8985 records on all fires in Latvia in 2019 gathered by State Fire and Rescue Service was performed to find out if gathered data is suitable and complete for establishment of statistical database for fire protection engineering. The purpose of the survey is to assess suitability of provided content for further studies of the characteristic building fire occurrence probabilities in different building occupancy classes and to obtain solid background for calculations of national values of fire activation partial safety factors which could be implemented in National Annex of Eurocode 1 part 1–2. Study contains data about the total number of building fires with relevance to their occupancy types and review of recorded fire causes for residential buildings that provide overall insight on typical causes of fires in dwellings.
Показать больше [+] Меньше [-]The assessment of chemical and ecological status in the water bodies of Slocene and Age [Latvia]
2020
Ikauniece, K., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Lazdins, A., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia)
Small rivers are important in terms of water quantity and quality as these rivers collect and deliver water to medium and large rivers downstream. Due to low water flow and high connectivity to adjacent land, small rivers are highly vulnerable to changes caused by natural and anthropogenic factors. This paper aims to assess the chemical and ecological quality of two small rivers including the Slocene and Age as related to dominant land use cover in the contributing area of these water bodies. The effects of land-use patterns and concentrations of chemical substances TN, NO3**- -N, NH4**+ -N, TP and PO4**2- -P in river waters will be determined. The highest concentration of total nitrogen (TN) as measured in the Slocene River was 21 mg LE−1 in spring, while the lowest concentration of TN was 0.86 mg LE−1 in autumn. The highest concentration of total phosphorus (TP) in the Slocene River was 0.14 mg LE−1 in late summer, the lowest was 0.03 mg LE−1 in late autumn. Similarly, in the Age River, the highest concentration of TN was 4.90 mg LE−1 in spring, while TN the lowest concentration of TN was 0.51 mg LE−1 in late autumn. The highest concentration of TP in the Age River was 0.3 mg LE−1 in summer, while the lowest 0.05 mg LE−1 in autumn.
Показать больше [+] Меньше [-]Response of barley on seaweed biostimulant application
2018
Szczepanek, M., UTP Univ. of Science and Technology, Bydgoszcz (Poland) | Jaskiewicz, B., Institute of Soil Science and Plant Cultivation – State Research Inst., Pulawy (Poland) | Kotwica, K., UTP Univ. of Science and Technology, Bydgoszcz (Poland)
In some regions of the world, there is a risk of limiting crop production due to the growing pressure of biotic and abiotic factors. It is mostly connected with the forecasted climatic changes. Hence, alternative methods for supporting plant growth are sought for, and among them, biostimulants can play a significant role. The three-year (2009 – 2011) field experiment with spring barley (Hordeum vulgare L.) was conducted in Poland to assess the response of grain yield, yield components, as well as the content and uptake of N, P and K in grain to differentiated times and to a dose of seaweed (Ecklonia maxima Osbeck) biostimulant Kelpak application. Preparation was applied in a dose of 2 L haE-1 at BBCH 22 (early treatment) or in a dose of 2 L haE-1 at BBCH 31 (late treatment), as well as two times, 1.5 L haE-1 each, in both phases. The study indicated that the biostimulant had a favourable effect on the root weight, grain number per spike, thousand grain weight and seed yield in early treatment as compared with the control. Early application also had a positive effect on N and P uptake in the grain yield. Favourable response of barley to the application of biostimulant shows the usefulness of the seaweed extract in the cultivation technology of this crop.
Показать больше [+] Меньше [-]Relationship of birch (Betula sp.) plywood bending properties determined according to the European standards EN 789 and EN 310
2007
Zudrags, K., Latvia Univ. of Agriculture, Jelgava (Latvia) | Tuherm, H., Latvia Univ. of Agriculture, Jelgava (Latvia)
The manufacturers of wood-based panels are interested to get easy and cheap method for determination of characteristic values of panels. The correlation between European standards EN 789 and EN 310 tests results can be used as an alternative procedure for determination of characteristic values of bending properties. The correlations between two results of bending properties determined by testing methods of European standards EN 789 and EN 310 are studied in this paper. The ratio of EN 789 test results divided with EN 310 test results (ratio of EN 789/EN 310), depending on panel thickness and glue type, was examined. Samples from 846 panels of birch (Betula sp.) plywood with thickness ranging from 6.5 to 30 mm and two glue types - phenol formaldehyde and melamine urea formaldehyde resin - were used for verification of the correlations. The results show that the panel thickness influences the ratio of EN 789/EN 310 and the highest ratio were found between 12 and 15 mm panels. When the panel thickness is increased or decreased, the ratio of EN 789/EN 310 decreases significantly. The regression equations for each thickness of plywood are presented. The difference between plywood glued with phenol formaldehyde and melamine urea formaldehyde resin glues was not found.
Показать больше [+] Меньше [-]Grades and standards: quality management from cradle to coffin
2005
Pedro Vilaseca
Another important aspect of an effective market is the quality of the goods that are sold. Standards to ensure the quality of goods are thus significant determinants of the effectiveness and productivity of markets. For the purpose of promoting competitive markets as well as protecting consumers from dangerous and unsafe products that may be found in the markets, the state can take a leading role in setting and enforcing quality standards.
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