2018

Selle valdkonna püsiv URIhttp://hdl.handle.net/10492/5371

Sirvi

Nüüd näidatakse 1 - 20 218

Energy valorisation of citrus peel waste by torrefaction treatment
(2018) Tamelová, B .; Malaťák, J.; Velebil, J.
The article deals with th e issue of processing and utilization of citrus peel, which often ends unused with other biodegradable waste. The research is concerned with the energy potential of this raw material and its torrefaction conversion. The tested materials were orange peel ( C itrus sinensis Osbeck cv 'Valencia', Citrus sinensis Osbeck cv 'Murcia') and grapefruit peel ( Citrus paradise 'Ruby red'). Samples of dried materials underwent torrefaction treatment at 225 °C , 250 °C and 275 °C for 30 minutes. Samples before and after tor refaction were analysed for proximate and elemental composition and for calorific value. Consequently, stoichiometric combustion analyses were done. The torrefaction was performed in a LECO TGA 701 thermogravimetric analyzer under nitrogen atmosphere. The results of proximate and elemental analysis showed positive influence of torrefaction on the samples. The highest net calorific value for orange peel is 24.97 MJ kg - 1 at the temperature of 275 °C . The greatest differences in net calorific values are betwee n 225 °C and 250 °C where the increase is almost 3 MJ kg - 1 . Subsequently, the increase between the 250 °C and 275 °C torrefaction temperatures is 1 MJ kg - 1 . Weight loss at respective torrefaction temperatures showed similar time - dependent curves for all sa mples. Stoichiometric combustion analysis shows slight differences between original samples, but great differences after torrefaction processing. Stoichiometric combustion parameters also change proportionately with increasing temperature of torrefication. The resulting comnbustion balance figures show significantly lower need for mass of fuel in the case of the torrefied material for a given heat output thanks to the net calorific value being nearly doubled.
Evaluation of greenhouse gas emissions and area of organic soils in cropland and grassland in Latvia – integrated National forest inventory data and soil maps approach
(2018) Petaja, G.; Okmanis, M.; Polmanis, K.; Stola, J.; Spalva, G.; Jansons, J.
The aim of the research was to assess distribution of organic soils in farmlands for the time period between 1990 and 2015, as well as to carry out a recalculation of GHG emissions from organic soils in grassland and cropland. We evaluated the area of typical organic soils using digitized soil maps created between 1960s and 1980s there were 183,000 ha of cropland and grassland on organic soils. A selected number of areas on organic soils intersecting with the National forest inventory (NFI) plots were surveyed. We found that 66 ± 10% of surveyed plots still conforms to criteria for organic soils according to Intergovernmental Panel on Climate Change (IPCC) guidelines; in the rest of plots soil organic matter has been mineralized and these areas do not conform to IPCC criteria of organic soils. The following distributionof organic soils was estimated in cropland – 6.3 ± 3.3% in 1990 and 4.1 ± 3.4% in 2015, but in grassland – 11.6 ± 3.6% in 1990 and 7.7 ± 3.9% in 2015. The annual reduction of GHG emissions due to reduction of area of organic soils in cropland in 2015 corresponds to 1,400,000 tonnes CO2 eq. in comparison to 1990 and in grassland – to 1,100,000 tonnes CO2 eq. The estimated reduction of the GHG emissions due to conversion of organic soils into mineral soils, comparing the average value in 2005–2009 with the projection for 2021–2030 on average will correspond to 313,000 tonnes CO2 eq. annually, however LULUCF sector still won’t become a net CO2 sink according to the GHG inventory data on other land use categories and carbon pools.
Effect of sunflower and rapeseed oil on production of solid particles and performance of diesel engine
(2018) Čedík, J.; Pexa, M.; Holůbek, M.; Mader, D.; Pražan, R.
The development of biofuels for compression ignition engines is heading primarily to utilization of vegetable oils. Combusting of 100% vegetable oil in unmodified CI engine is usually not possible due to higher viscosity of the vegetable oil. In order to use 100% vegetable oil in CI engine the oil needs to be preheated, esterified or hydrotreated. Alternatively, in orde r to use raw vegetable oil in CI engine without preheating it is possible to use vegetable oil – diesel fuel blends or vegetable oil – butanol – diesel fuel blends in order to lower the viscosity of the fuel. The contribution focuses on comparison of the e ffect of sunflower and rapeseed vegetable oils on operational parameters of the turbocharged compression ignition engine, especially on production of solid particles. The measurement was carried out according to standardized NRSC test cycle. 5% and 20% con centration of vegetable oils in diesel fuel were used as a test fuels for the measurement while the diesel fuel was used as a reference. The count and size of solid particles were measured by means of EEPS particle analyser. Based on the measured values it can be stated that the slight increase of performance parameters occurred with strong effect on emissions production, especially on production of solid particles.
Sapropel processing approaches towards high added-value products
(2018) Obuka, V.; Boroduskis, M.; Ramata-Stunda, A.; Klavins, L.; Klavins, M.
Sapropel is an organic sediment from fresh water bodies that is widely distributed in the northern regions of the w orld. The distribution and unique properties of sapropel make it an important natural resource that can be used in agriculture , horticulture, forestry and farming directly as obtained. The aim of this study was to investigat e the extraction possibilities of sapropel and potential applications of its extracts. Humic substances constitute an important ingredient of sapropel, and they can be extracted by mild alkaline extraction. Humic substances from peaty sapropel have signifi cant differences in composition and properties, thus demonstrating the impact of precursor biological materials on the properties of humic substances formed in the humification process .
Study of potential PCR inhibitors in drinking water for Escherichia coli identification
(2018) Dalecka, B.; Mezule, L.
In the last few decades, the polymerase chain reaction (PCR) has become one of the most powerful molecular biological tools. However, the PCR is an enzymatic reaction and therefore sensitive to inhibitors which may occur in drinking water samples. In this work, the possible inhibition effect of chlorine, humic acids, and iron for real - time PCR (qPCR) efficiency was studied and the environmental sample from drinking water treatment system before iron removal was selected and analysed. The results demonstrate d that the highest concentrations of humic acids (5 mg L - 1 and 1 mg L - 1 ) and iron (4 mg L - 1 ) inhibited the PCR reaction while no effect of chlorine was observed. The analysis of the environmental sample with spiked Escherichia coli cells demonstrated reduc tion efficiency of the average threshold cycle (C t ) values compared with control dilution series determining the possible inhibition for qPCR assay.
Shrinkage effect on diffusion coefficient during carrot drying
(2018) Aboltins, A.; Rubina, T.; Palabinskis, J.
Many studies have been previously carried out on the carrot drying and the undergoing processes. The developed mathematical models provide an opportunity to gain an understanding of this complex process and its dynamics. But they are sim plified and based on a number of assumptions, including calculation of diffusion coefficient values. In one of the previous studies, the authors of this study determined that the diffusion coefficient is linearly dependent on the moisture concentration wit h the assumption that the sample's geometric shape does not change. The aim of this study is to determine the dependence of the diffusion coefficient on the moisture concentration taking into account the change in sample thickness during the drying experim ent. The experiments were carried out with carrot slices of three different thicknesses: 5 mm, 10 mm and 15 mm thickness on the film infrared dryer at temperature 40 °C . During the experiments, measurements of the weight and thickness of the slices were pe rformed. Using the experimental data the average thickness and diffusion coefficient of slices was calculated depending on the moisture concentration . Obtained results show that thickness depends linearly on the moisture concentration. Using experimental d ata and obtained average values of samples thickness, the values of diffusion coefficient was calculated. The results indicate that diffusion coefficient value depend linearly on moisture concentration. Their values are close and tend to zero when the conc entration decreases if the thickness changes are taken into account during the experiment.
Meat chemical composition of pasture pure lambs and crossbreeds
(2018) Vecvagars, J.; Bārzdiņa, D.; Kairiša, D.
Increased customer interest of safe, healthy and environmentally friendly food consumption promote development of sheep farming industry in Latvia. Aim of the paper – explain of different pasture - fattened sheep breed and their crosses lamb meat composition traits. A study of pasture fattened lamb meat chemical composition was carried out from year 2013 to 2017. Fattening lambs were kept in breeding rams control station ‘Klimpas’ (57°50’58.8’’N 25°19’39.6’’E) pasture array. Lambs were slaughtered in a certif ied slaughterhouse, but analysis of meat chemical composition were conducted in laboratory of Institute of Food Safety, Animal Health and Environment (BIOR). For the analysis of the meat chemical composition were used up to 1 kg heavy Quadriceps femoris mu scle samples. In meat were analysed following elements of its chemical composition: dry matter, protein, fat, minerals, pH, cholesterol and unsaturated fatty acids. Data analysis shows that the lambs before slaughter ranged in age from 5 to 8 months. Lamb meat obtained from the study groups had a significantly different total amount of dry matter and fat. The lowest total fat, but the highest ash content was obtained in the lamb meat of the extensive breed group. The lowest total fat and the highest ash con tent were obtained in the lamb meat from the extensive breed group. In meat obtained a small (in individual samples < 0.10%) cis - 10 - pentadecenoic acid, cis - 11 - eicosenoic acid and myristoleic acid content. Of unsaturated fatty acids in lamb meat were represented higher amount of oleic acid, linoleic acid and elaidic acid.
Harvest time and ensilage suitability of giant reed and miscanthus for bio-methane production and characterization of digestate for agronomic use
(2018) Da Borso, F.; Di Marzo, C.; Zuliani, F.; Danuso, F.; Baldini, M.
In many countries, biogas plants are mainly fed by livestock slurry and dedicated crops, including maize, which still represents one of the main energy crops utilized. Many concerns are now arising on environmental impact due to the high water consumption, chemical fertilizer and pesticide requirements and on adverse effect of maize as energy crop on the price of food and feed commodities. For these reasons two perennial crops, in particular miscanthus (Miscanthus x giganteus) and giant reed (Arundo donax L.), were cultivated at very low input and evaluated for their bio-methane yield at different harvest times and ensilage suitability, in a north-eastern area of Italy. Moreover, considering the agronomic use of the obtained digestate as fertilizer, this has been characterized by the content of heavy metals. Both multi-annual crops have proved highly productive in biomass especially with a harvest time in autumn, at which a satisfactory completion of the silage process without additives was observed. Conversely, bio-methane yield per hectare were not satisfactory with respect to the reference crops such as maize. The low BMP attained showed the main bottleneck of the methanisation of ensiled giant-reed and miscanthus, which is represented by fiber composition with high degree of lignification. The simulation use of digestate obtained as fertilizer in vulnerable areas, could lead to slightly exceed the levels allowed by the legislation of some European countries with regard of heavy metals as Cu, Zn and Cd.
Volatile combustible release in biofuels
(2018) Vitázek, I.; Majdan, R.; Mojžiš, M.
Plant biomass consists of varied materials. Biomass is used for different purposes, but it is most frequently burnt in modern combustion devices for heat production. The quality of solid biofuels depends on the total content of combustibles while the volatile combustible content affects the combustion process. The aim of the paper is to determine the exact content of the biofuel components by the means of the gravimetric method – namely volatile combustible, ash and moisture content – and to evaluate the process of volatile combustible release as a function of temperature during the experiment. The device Nabertherm L9/11/SW/P330 type with accessory was used to carry out the experiments. Various biofuel samples were examined, namely wood (9 kinds), wood cuttings and wood chips (2 kinds), pellets (4 kinds), sawdust (1 kind), compared to less traditional fuels (DDGS and RME – 2 kinds) and wood coal (1 kind). The tables and graphs present the experimental results, which allow evaluation of the components content in different biofuels and provide characteristics of the process of volatile combustible release in analysed fuels. Spruce wood without bark showed the highest content of combustible (99.89%). Sawdust of fruit trees contains the highest proportion of volatile combustible (93.978%) and releases the combustible at the highest rate (15.25 mg h-1).
Molecular genetics analysis of milk protein gene polymorphism of dairy cows and breeding bulls in Latvia
(2018) Smiltina, D.; Grislis, Z.
Milk protein is the most valuable component of milk from a dietary point of view. More than 95% of ruminants’ milk proteins are coded by six structural genes: two whey proteins (α – lactalbumin and β – lactoglobulin) and four caseins (α S1 – and α S2 – caseins, β – casein, κ – casein). The object of the research was the genetic polymorphisms of milk protein genes in populations of cows and breeding bulls of milk producing breeds in Latvia. The aim was to promote cow breeding in Latvia by developing and testing mo lecular genetics analyses for future quantity and quality analysis of the dairy cows’ population in Latvia, based on the research of genes encoding milk protein polymorphism. In methodology the molecular markers were chosen which would be suitable for char acterization of polymorphism of five milk protein genes in the population of dairy cows reared in Latvia. As a genetic method chosen the Restriction Fragment Length Polymorphism (RFLP) method and most analysed alleles of milk proteins. Using data of 719 DN A samples of dairy cows, the analysis of Latvian cows’ population was carried out through six SNP of five milk protein genes: C SN1S1 c. – 175 A > G, CSN2 – c. 4451 A > C, CSN3 c. 11625 C > T and c. 11661 A > C, LAA c.15A > G and LGB c. 3106T > C. The results of PCR - RFLP analysis showed, as it was expected, that all genotypes were found in the populations.
Modelling of operator’s focusing scheme along working hours: Windrowing and cultivating operations
(2018) Szabó, I.; Hushki, M.; Bártfai, Z.; Lágymányosi, A.; Kátai, L.
Enhancing productivity and cost reduction are two main targets for any production operation. In the agricultural field; It is the role of researchers to come out with reliable models and make it available to be used in m odern farming management organizations as well as to the rural farmers. When it comes to the Human Machine Interface it is essential to assess the system in term of the Human Cantered Design aspects. This research is focusing on the developing simple model s for the operator’s focusing scheme as a human behaviour inside an off - road vehicle cabin based on the operator’s focusing scheme measuring along working hours using proven and up to date technologies. The results of this research provide the decision mak ers with reliable inputs using proven methodology regarding the change of operator’s focusing scheme along working hours in two agricultural operations “windrowing and cultivating”. Both operations are requiring continuous physical involvement of the opera tor for checking the attached tool and steering of the vehicle in the planned track, which is directly related to the accumulated passive fatigue as a main contributor of resulted data.
The excretion of Ca, Mg, Zn and Cu via excreta of laying hens fed low phosphorus diets and phytase
(2018) Kamberi, M.A.; Muji, S.; Kryeziu, A.; Kastrati, R.; Mestani, N.
An 8 – week experiment was conducted to study the effect of adding phytase (Natuphos ® 5000 BASF) to low and normal available phosph orus diets of laying hens on the excreta content and excretion of Ca, Mg, Zn and Cu. A total of 144 Hisex Brown laying hens that were 22 weeks old at the start of the experiment were randomly assigned to four dietary treatments. Treatments included three r eplicates (12 hens each) or 36 hens per treatment in total. Four corn - soybean meal - based diets were formulated to contain two levels of available phosphorus (AP; 0.12 and 0.46%) and two phytase levels (0 and 600 FTU kg – 1 ). The results showed that there was no significant effect of added phytase on excreta Ca and Mg content ( P > 0.05), but there was a significant effect of the dietary treatment on the content of Zn ( P = 0.0075) and Cu ( P = 0.0002). In terms of the excretion of these mine rals, the dietary treatment had no effect on Ca and Zn excretion and a borderline effect ( P = 0.0522) on Mg excretion measured as the amount of the mineral excreted per egg mass produced is observed. The results however showed a very strong effect of all three factors (available phosphorus, phytase and their interaction) on Cu excretion. The r esults indicate that adding 600 FTU to the corn - soybean meal laying hen diet with 0.12% or 0.46% AP beneficially affects the content and the excretion of Ca, Mg, Zn and Cu. Therefore, we can conclude that a laying hen diet containing 0.12% available phosphorus and 600 FTU during the first production cycle may not only satisfactorily support hens’ perf ormance but will also beneficially affect the environment.
Production and characterization of Al-BN composite materials using by powder metallurgy
(2018) Yonetken, A.; Erol, A.
Aluminum matrix composites containing 3, 6, 9, 12 and15% BN has been fabricated by conventional microwave sintering at 550 °C temperature. Compounds formation between Al and BN powders is observed after sintering under Ar shroud. XRD, SEM (Scanning Electron Microscope), mechanical testing and measurements were employed to characterize the properties of Al + BN composite. Exper imental results suggest that the best properties as hardness 42, 62 HV were obtained for Al+12% BN composite.
Ergonomic modelling parameters and the influence of ergonomics on planning workplaces
(2018) Maksimov, D.G.; Kalkis, H.
Modern economic research divides all economics into structural levels: mega - economics, macroeconomics, meso - economics, micro - economics, and nano - economics. From the point of such traditional divisions, the research is topical in the primary economic struct ure of society – nano - economics – and thanks to this work operations can be subdivided into workplaces in the form of transformation processes. The aim of the research is to develop ergonomic modelling parameters and to discover the influence of ergonomics on the planning of workplaces ba sed on a case study. The research involved a study of workplace ergonomic planning methods and principles. Solutions for a series of problems which are related to the improvement of workplace ergonomics may be discovered in the following ways: improving wo rk organisation in every workplace by using work process - related micro - elemental methods and a determination of work expenditure, the levels of physical strenuousness involved in the work, the complexity of the work, and the social importance of the workpl ace. These parameters will allow the workplace quantity characteristics to be discovered, such as in terms of a generalised parameter which conforms to the requirements which describe a workplace, and in terms of operational management via the condition of workplaces and the salary systems being utilised. The research provides a case study in which ergonomic modelling parameters are developed and concrete workplace interventions are introduced.
Agricultural residues in Indonesia and Vietnam and their potential for direct combustion: with a focus on fruit processing and plantation crops
(2018) Brunerová, A.; Roubík, H.; Brožek, M.; Velebil, J.
Energy consumption in Indonesia and Vietnam has grown rapidly in recent decades. To meet the energy needs of both countries, a higher utilisation of waste biomass sources may represent an adequate solution. Investigated samples represent major crop residues (waste biomass) originating mainly from the agriculture sector of the selected countries. Herbaceous waste biomass from Indonesia is, namely, cassava stems and root peelings ( Manihot esculenta ), coffee leaves ( Coffea arabica ), cacao leaves ( Theobroma cacao ), banana leaves ( Musa acuminata ), bamboo leaves ( Bambusoideae spp.) and aloe vera leaves ( Aloe vera ). Furthermore, fruit and aquatic waste biomass originating from Vietnam is, specifically, sugarcane bagasse ( Saccharum officinarum ), durian peelings ( Durio zibethinus ), rambutan peelings ( Nephelium lappaceum ), banana peelings ( Musa acuminata ), water milfoil ( Myriophyllum spicatum ) and water hyacinth ( Eichhornia crassipes ). All mentioned types of waste biomass were subjected to proximate and calorimetric analysis: moisture, ash and volatile matter contents (%) and higher and lower heating values (MJ kg – 1 ). Obtained values indicated the highest level of ash content in fruit bioma ss samples in the case of sugarcane bagasse (0.84%), in herbaceous biomass in the case of cassava stems (3.14%) and in aquatic biomass in the case of water hyacinth (14.16%). The highest levels of lower heating values were achieved by following samples (be st samples from each biomass type): cassava stems (17.5 MJ kg – 1 ); banana peelings (17.3 MJ kg – 1 ) and water hyacinth (12.8 MJ kg – 1 ). The overall evaluation of all observed samples indicated that the best suitability for energy utilisation by direct combusti on of investigated representatives is fruit waste biomass, followed by herbaceous waste biomass and then aquatic waste biomass.
Environmental risk assessment studies on new plant protection products which have been elaborated from coniferous tree bark
(2018) Jankevica, L.; Polis, O.; Korica, A.; Samsone, I.; Laugale, V.; Daugavietis, M.
Nowadays there are still various chemical pesticides being applied in the course of ensuring plant protection. Since 2010, we have been working on the development of new, environmentally-friendly plant protection products which will provide an effective tool against pathogenic fungi and bacteria which cause disease in crop plants. The specific aim of this study was to evaluate a risk assessment for new plant protection products that have been elaborated on the basis of coniferous tree bark. Various products were tested which are extracted during the processing of wood bark from pine (Pinus sylvestris L.) and spruce (Picea abies (L.) Karst.). Ethanol extracts were formulated and applied during these experiments. Two formulations, which showed anti-fungal activity in vitro and in field trials on fruit crops (involving strawberries and raspberries) were selected for the risk assessment studies. The impact was studied of formulation treatment on crop plants and soil biological activity, and the accumulation of residues of active substances in crop plants and soil. The application of new formulations did not show any negative effect on the chlorophyll content and the chlorophyll fluorescence of plant leaves. The results showed that pine and spruce bark extract formulations contain active compounds (coumaric acid, quercetin, epicatechin, and ferulic acid) within the range of 5.1–5.9 mg kg-1 and 11.1– 443.9 mg kg-1 respectively. The amount of active substances which were determined in most cases was higher in the spruce bark extract formulation when compared to the pine bark extract formulation. Our results confirmed the presence of active compounds – epicatechin, quercetin, and coumaric acid – in strawberry fruits which remained untreated and in those that were treated with spruce ethanol extract formulation. Untreated raspberry fruits contained all four active substances within the range of 81–5,300 µg kg-1. We observed a significant increase of coumaric acid and quercetin in raspberries after their having been treated with spruce bark extract formulation in a 2% concentration, P < 0.05, and did not find any negative impact for spruce bark extract formulations when used on soil microbial biomass.
Agricultural field production in an ‘Industry 4.0’ concept
(2018) Jørgensen, M.H.
Precision Agriculture is a well-established concept in agricultural field production. It has developed over the last three decades. As part of this concept, farmers are used to collect and handle data. Farmers are also used to create solutions for field operations based on their knowledge of diversity and local data. When compared to classic industrial production, agricultural field operations interact with a biologically-active system. From a production management system point of view, industrial production takes place in close, well-defined environments in which performance data can, to a great extent, be measured by deterministic matters: mass (kg), volume/dimensions (m3 /m), time (sec), etc. In agricultural operations such as work involving tillage, seeding, fertilising, and plant care, there are by nature a good many possible adjustments available in order to optimise the operation method, plus intensity and timing. The challenge here is to establish the levels of knowledge that are necessary to support the control of the individual and/or graduated, precision-based operations. Within this context, parameters such as, for example, the workability of the soil cannot be defined in terms of a few deterministic parameters. Neither can the operational impact upon the soil which is made by the tools being used. It is assumed that this challenge is part of the reason why the concept of precision agriculture still contains a great deal of unutilised potential. The hypothesis raised by this article is that analysis should be carried out in regard to whether inspiration for the concept of an ‘Industry 4.0’ can facilitate the establishment of operational solutions in the field of precision farming.
Effect of nitrogen fertilization on winter wheat yield and yield quality
(2018) Litke, L.; Gaile, Z.; Ruža, A.
Wheat ( Triticum aestivum L.) is the most common cereal, which is grown in Latvia. Nowadays, farmers are trying to get high grain yields in line with food quality, at the same time trying to minimize production cos ts and to use environmentally friendly technologies. The objective of this experiment was to clarify the impact of nitrogen fertilization on winter wheat yield and yield quality under two soil tillage systems and after two forecrops. Trials were conducted at the Research and Study farm ‘Peterlauki’ of Latvia University of Agriculture (56 ° 30.658 ’ N and 23 ° 41.580 ’ E). Researched factors were (1) crop rotation (wheat/wheat and oilseed rape ( Brassica napus ssp. oleifera )/wheat), (2) soil tillage (traditional soil tillage with mould - board ploughing at a depth of 22 – 24 cm and reduced soil tillage with disc harrowing at a depth below 10 cm ), (3) nitrogen fertilizer rate (altogether eight rates: N0 or control, N60, N90, N120(90+30), N15 0 (90+60) , N180 (90+60+30) , N210 (90+70+50) , and N240 (120+60+60)), and (4) conditions of the growing seasons 2014/2015, 2015/2016 and 2016/2017. The results indicate that winter wheat yield has been significantly affected by soil tillage, nitrogen fertilizer rate ( p < 0.001) and forecrop ( p < 0.05). Three - year research confirmed significant yield increase until the nitrogen fertilizer rate N180. Significantly higher average grain yield was obtained under traditional soil tillage. Nitrogen fertilizer affected significantly all tested yield quality indicators ( p < 0.001) . Increase of nitrogen fertilizer rate secured significant increase of winter wheat grain quality indices, except starch content, after both forecrops and in both soil tillage variants. Values of yield quality indicators increased significantly enhancing N - rate from N150 up to N 210.
The influence of drying method to the changes of bioactive compounds in lingonberry by-products
(2018) Ozola, L.; Kampuse, S.
The aim of this research was to evaluate the effect of different drying methods on industrially obtained lingonberry pulp juice by - products. For investigations, by - product was dried using hot air dryer (at temperatures 80 °C , 60 °C and 40 °C ), microwave - vacuum dryer and freeze - dryer. The freshly defrosted by - product was used as control. All samples were analysed on the basis of their moisture content, colourimetric attributes (CIE L*a*b* colour system), content of vitamin C (iodometric method), content of total carotenes (TC), total phenol content (TPC), total anthocyanin content (TA) and antiradical activity (DPPH, ABTS + ). The obtained data on content of vitamin C showed a 10% decrease between control and sample dried in hot air at 80 °C . Similar changes were noticed with total anthocyanin content, the lowest amount was also foun in this sample ( 306.72 ± 18.32 mg 100 g - 1 DW). Total carotenes content was higher in freeze - dried sample (5.61 ± 0.16 mg 100 g - 1 DW) which was very close to control sample. A significant loss of total phenol content was noticed after drying, up to 80%, similar ten dencies were noticed with changes of antiradical activity. After evaluating the obtained data, the use of hot air dryer at 80 °C temperature resulted in the lowest amount of vitamin C and anthocyanins in lingonberry by - products, which makes this method unsuitable for drying by - products of these berries. However, vacuum assisted microwave drying and freeze drying showed less damaging impact on dried material.
Assessment of Calotropis natural dye extracts on the efficiency of dye-sensitized solar cells
(2018) Alami, A.H.; Aokal, K.; Zhang, D.; Tawalbeh, M.; Alhammadi, A.; Taieb, A.
This work presents the construction and testing of solar cells sensitized with natural dyes extracted from plants indigenous to the desert. Calotropis plants are self - sufficient as they grow in very harsh environments, and yet are not consumed by humans or livestock due to their irritating agents to the skin and eyes. The energy generators of these plants are the leaves, which are crushed and processed to produce the dye solution. Also, the Calotropis leaves are covered in a white powder that is thought to aid in mitigating the heat by scattering incident radiation. This powder material is examined and added to the dye as it proved advantageous for the o verall cell efficiency, which reached 0.214% compared with 0.108% for cells with no powder. The produced cells are also compared with ones sensitized by spinach, another common natural sensitizer for dye - sensitized solar cells, and the performance proved t o be significantly better. The fact that Calotropis is a non - food plant is an added advantage to utilizing it as a dye source, along with its intrinsic heat resistance that allows it to survive the harsh desert conditions all year round.

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