The COVID-19 infectious disease in 2020 caused a global and subsequent lockdown policies imposed by various governments. Public libraries were affected as well. For many public libraries, the only ...one that remained active and available to users was access to their digital content. The Njegoš public library in Knjaževac, Serbia, responded by improving access to, and promoting, its vast digital content. The library also monitored access to the digital library, hypothesizing that the conclusions from the statistical data would bring insights and future improvements. The statistical data from the website of the public library revealed users' most popular times of day and days of the week during the pandemic and in normal times. Regarding the devices used for access, there was a trend toward more up-to-date operating systems and also toward mobile devices. The average time reading increased by approximately 130%, with the highest peak during the most restrictive lockdown in March 2020. Thus, digital library servers should have the capacity to handle such increases in network traffic, at increased download speeds. Library posts on social media, specifically Facebook, were viewed an order of magnitude times during the pandemic when compared with posts from the previous year. Thus, social media posts were an effective pathway for promoting the digital library during the pandemic-induced lockdown.
Much progress was made in the straightforward and eco-friendly enzymatic synthesis of shorter cellulose chains (oligocellulose). Here, we report the determination of a molar mass distribution of the ...oligocellulose synthesized from cellobiose (CB) and α-glucose 1-phosphate by reverse phosphorolysis, using enzymes cellodextrin phosphorylase from Clostridium stercorarium or Clostridium thermocellum as catalyst. The oligocellulose molar mass distribution was analyzed using three different methods: 1H NMR spectroscopy, matrix assisted laser desorption/ionization–time-of-flight mass spectrometry (MALDI-ToF MS) and size exclusion chromatography (SEC). The molar mass distribution of the synthesized oligocellulose was only dependent on the concentration of cellobiose used in the reaction. Data obtained from MALDI-ToF MS and SEC were almost identical and showed that oligocellulose synthesized using 10 mM CB has an average degree of polymerization (DP n ) of ∼7, while a DP n of ∼14 was achieved when 0.2 mM CB was used in the reaction. Because of solvent limitation in SEC analysis, MALDI-ToF MS was shown to be the technique of choice for accurate, easy and fast oligocellulose molar mass distribution determination.
The aim of this study was to evaluate element (sodium, magnesium, potassium, calcium, chromium, manganese, iron, cobalt, nickel, copper, zinc, arsenic, cadmium, and lead) deposition in honey bees (
...Apis mellifera
L.) (worker bees, drone bees, and bee broods) and their products (wax and multifloral honey) in the central and north parts of Serbia using inductively coupled plasma mass spectrometry (ICP-MS). The study was carried out during the spring and summer seasons when the honeybees were active (2019). Fifty-four colonies of honey bees from different apiaries (located in Rudnik, Lazarevac, and Ležimir) were used in this study. Significant differences in element concentrations were found among locations (
P
< 0.05). The highest deposition of elements (sodium, calcium, manganese, iron, cobalt, nickel, zinc, arsenic, and cadmium) was found in worker bees. The most commonly detected elements in wax were chromium and lead. Mg had a significant (
P
< 0.01) correlation with K, Fe, Cu, and As. This study shows that honey bees (worker bees, drone bees, and bee broods) could be more useful as bioindicators of environmental element deposition (toxic and non-toxic) than multifloral honey. Also, this study shows that Serbian multifloral honey meets safety criteria concerning the concentrations of toxic elements.
The aim of this study was to investigate the presence of heavy metals/metalloids (Pb, Cd, Hg, Cu, Fe, Zn, As) in the muscle tissue of fish from the Danube River (two locations: Zemun and Grocka). For ...the purpose of heavy metal determination in fish muscle, 120 samples of six different fish species, Prussian carp, barbel, bream, carp, pike perch, and catfish were collected. For determining heavy metals, we used microwave oven digestion and atomic absorption spectrometer methods. The highest average content of Pb (0.084 ± 0.004 mg kg
−1
), Cd (0.082 ± 0.003 mg kg
−1
), Hg (0.466 ± 0.006 mg kg
−1
), and As (0.333 ± 0.007 mg kg
−1
) was found in the muscle of carp (an omnivorous fish) from Grocka, while the highest average level of Fe (13.60 ± 0.03 mg kg
−1
) was deposited in bream (also omnivorous) from Zemun. Also, the average Cu level (1.62 ± 0.13 mg kg
−1
) was the highest in catfish muscle (a carnivorous fish) from Grocka, while the highest Zn content (11.16 ± 0.17 mg kg
−1
) was determined in muscle of Prussian carp (an omnivorous fish) from Zemun. The highest content of heavy metals (Cu, Fe, and Zn, respectively) in muscle of the six different types of fish from both locations was symmetrically arranged by species (catfish, barbel, and Prussian carp, respectively). Concentrations of Pb, Hg, and As in the Danube River fish muscle were under the maximum residual levels prescribed by the European Union (EU) and the maximum allowed concentrations (MAC) for Serbia. On the other hand, in all fish muscle from both locations (Zemun and Grocka), higher concentrations of Cd than prescribed (MAC) were found, with the exception of bream and pike perch.
Abstract
The present study was conducted to assess effects of selenium (Se)-yeast supplementation on glutathione peroxidase activity, Se levels in tissues, growth performance, carcass, and meat ...composition in broilers. A total of 275 one-d-old Cobb 500 broilers of both sexes were randomly allotted to 1 of 5 treatments during a 42-d period. The 5 treatments differed only in Se content: group 1 had no additional Se (background only); groups 2, 3, and 4 received 0.3 mg/kg of added Se from the beginning of the trial until d 21, whereas in the second half of the study (from d 22 to 42), these groups received 0.3, 0.6, and 0.9 mg/kg of added Se, respectively; and group 5 received 0.9 mg/kg of Se for the entire experimental period. At the end of the study, the control group showed significantly lower (P < 0.01) glutathione peroxidase activity in blood plasma compared to Se-supplemented groups. Regarding Se concentration in various tissues, the groups receiving Se yeast showed higher plasma, feces, and meat Se contents than the control group (P < 0.01). Supplementation of Se improved broilers' body weight, weight gain and feed conversion ratio (P < 0.01). Dressing percentage was lower in the control group and the group with 0.3 mg/kg of added Se compared to other experimental groups (0.6 and 0.9 mg/kg of dietary Se). The proportion of less valuable carcass parts (wings and legs) was higher (P < 0.01) in the group fed the basal diet compared to groups supplemented with 0.9 mg/kg of Se. Initial and ultimate pH values differed among experimental groups (P < 0.05). Supplementation of Se improved the broiler's antioxidative resistance, growth performance, carcass quality, and chemical composition of meat.
American foulbrood (AFB) is exclusively an infectious disease of honey bee larvae (
) and their subspecies that is spread easily and rapidly and is often present in apiaries. Due to the resistance ...and pathogenicity of the bacterial causative agent of the disease, which has considerable epizootiological and economic significance for beekeeping, AFB was classified as a highly dangerous, infectious animal disease by the World Organization for Animal Health (WOAH). Considering the severity of the infection, a frequent occurrence, rapid and easy spread, epizooty and enzooty are common. We tried to present an overview of the latest information related to AFB through several chapters. In addition to the latest data on the etiology of the causative agent, the most important elements of the clinical signs of the disease are also listed. Along with an overview of classic microbiological and the latest molecular methods of diagnosis, we also discuss AFB treatment from its differential diagnostic aspect. We hope that through demonstrating the mentioned preventive measures and measures of good beekeeping practice, the review will contribute to the preservation of the health of bees and therefore the overall biodiversity of the planet.
Concentrations of toxic elements (lead, cadmium, mercury, and arsenic) were measured in water, sediment, and four commercial fish species (
Cyprinus carpio
,
Hypophthalmichthys molitrix
,
Silurus ...glanis
, and
Esox lucius
) and their tissues (muscle, liver, and kidney) from Saničani Lake, Bosnia and Herzegovina. The concentration of toxic elements was measured by atomic absorption spectrometry. Toxic element concentrations were significantly affected by the fish species and tissues sampled. The lead was the most heavily deposited element in lake sediments and waters. The highest concentrations of Pb and Cd were in the kidney in all four fish species. Concentrations of Hg and As were higher in the muscle than in the kidney and liver in all four fish species. The toxic element concentrations in all examined tissues were significantly higher in
Silurus glanis
and
Esox lucius
than in the other fish species examined. Concentrations of all tested elements were present in the fish muscle at different levels, but these levels were under the maximum levels allowed by the European Union and FAO/WHO. Accordingly, fish meat from this lake is acceptable for human consumption.
Honey is a natural substance produced by honey bees (the genus
Apis
) enjoyed by people due to its unique nutritional and medicinal properties. The aim of this study was to determine the ...physicochemical parameters (moisture, ash, water-insoluble content, reducing sugars, sucrose, free acidity, diastase activity, hydroxymethylfurfural, and electrical conductivity) and microbiological status (total number of aerobic mesophilic bacteria, total number of sulfite-reducing clostridia, the presence of
Salmonella
spp., total numbers of fungi and yeasts and the presence of
Clostridium botulinum
) in honey (honeydew, blossom, sunflower, acacia, and linden) produced in an urban environment in Serbia. We analyzed 19 apiary samples of honey, collected during the 2011 harvesting season, by using recommendation methods. Physicochemical parameters of the examined honey produced in the urban environment indicated the honeys were of acceptable quality.
Bacillus
spp. were detected in four honeys, yeasts were detected in three honeys, and
Clostridium botulinum
type E was detected in one honey using PCR. The current study also showed the presence of diverse honey varieties in Serbia.
The physicochemical parameters (free acidity, moisture content, sucrose content, hydroxymethylfurfural, reducing sugars, electrical conductivity, diastase activity and water-insoluble content), ...elements (Cu, Fe, Zn, Mn, Cr, Co, Ni, Se, K, Na, Ca, Mg) and heavy metal/metalloid concentrations (Cd, Hg, Pb and As) of 84 honeys (linden, multifloral, honeydew and acacia) from Serbia, were analyzed using ICP-MS. Concerning the physicochemical parameters, all tested honeys were found to meet European Legislation (EC Directive 2001/110). Potassium was the major element, ranging between 943.9 ± 538.6 mg/kg and 2563 ± 1817 mg/kg. Statistical analysis showed significant differences in the concentrations of Zn, Mn, Co and Na between the honeys. Selenium and Hg levels were below the limits of detection. Positive correlations were found between electrical conductivity and most of the elements. The present study showed that Serbian honey examined were of good quality according to its physicochemical parameters and met safety criteria concerning the concentrations of Cd, Hg, Pb and As.
Bee bread can be defined as a popular bee product (behind honey, propolis, beewax, bee pollen, royal jelly and apitoxin), a natural substance, a mixture of bee pollen, honey and lactic acid bacteria ...that is the result of lactic acid bacteria (LAB) fermentation of bee pollen collected by bees from the natural environment, and is the protein basis of food in the beehive.
Primarily, honey bees use bee bread for brood growing (nutrition), but humans use bee bread in folk medicine and apitherapy, but also as a functional food, according to the bread's powerful healing properties and content of different molecules (bioactive, antibacterial, antifungal, antiviral, etc.). The biological properties of bee bread depend on its chemical composition, the melliferous plants in the region, geographical area, season, climatic conditions, etc.
According to its chemical and nutritional properties, bee bread is more valuable (higher biological value, faster digestibility and better chemical composition if compared to bee pollen) than bee pollen. Bee bread contains about 250 different substances, such as proteins, macro- and microelements, lipids, free amino acids, fatty acids (linoleic, linolenic and arachidonic), flavonoids, phenolic compounds, vitamins, and enzymes. Many different scientific articles have been published in international journals with focus on the chemical composition of honey, bee pollen and propolis. This paper contributes to the knowledge of the chemical composition, nutritional value and bioactivity of bee bread.
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