946 resultados para globular heads
Resumo:
Two new Streptomyces phages, øBP1 and øBP2, were isolated from tropical soil samples. These phages presented a large host range and developed both lytic and lysogenic responses in different Streptomyces species tested. Variations in the incubation temperature showed to be important in the development of the replication cycle. Increasing incubation temperature from 30oC to 42oC induced the lytic response of øBP2 and lysogenic of øBP1 in the host strain Streptomyces sp. WL6. øBP1 and øBP2 have icosahedral heads with long tails and were characterized in relation to morphology, G + C content, genome size and adsorption curve
Resumo:
The structure of the large proteoglycan present in the bullfrog epiphyseal cartilage was studied by immunochemical and biochemical methods. The isolated monomer showed a polydisperse behavior on Sepharose CL2B, with a peak at Kav = 0.14. Chondroitin sulfate chains were identified by HPLC analysis of the products formed by chondroitinase digestion and mercuric acetate treatment. These chains have approximately 38 disaccharides, a Di45:Di68 ratio of 1.6 and GalNAc4S + GalNAc4,6S are the main non-reducing terminals. Keratan sulfate was identified by the use of two monoclonal antibodies in Western blots after chondroitinase ABC treatment. A keratan sulfate-rich region (~110 kDa) was isolated by sequential treatment with chondroitinase ABC and proteases. We also employed antibodies in Western blotting experiments and showed that the full length deglycosylated core protein is about 300 kDa after SDS-PAGE. Domain-specific antibodies revealed the presence of immunoreactive sites corresponding to G1/G2 and G3 globular domains and the characterization of this large proteoglycan as aggrecan. The results indicate the high conservation of the aggrecan domain structure in this lower vertebrate.
Resumo:
It is well known that the interaction of polyelectrolytes with oppositely charged surfactants leads to an associative phase separation; however, the phase behavior of DNA and oppositely charged surfactants is more strongly associative than observed in other systems. A precipitate is formed with very low amounts of surfactant and DNA. DNA compaction is a general phenomenon in the presence of multivalent ions and positively charged surfaces; because of the high charge density there are strong attractive ion correlation effects. Techniques like phase diagram determinations, fluorescence microscopy, and ellipsometry were used to study these systems. The interaction between DNA and catanionic mixtures (i.e., mixtures of cationic and anionic surfactants) was also investigated. We observed that DNA compacts and adsorbs onto the surface of positively charged vesicles, and that the addition of an anionic surfactant can release DNA back into solution from a compact globular complex between DNA and the cationic surfactant. Finally, DNA interactions with polycations, chitosans with different chain lengths, were studied by fluorescence microscopy, in vivo transfection assays and cryogenic transmission electron microscopy. The general conclusion is that a chitosan effective in promoting compaction is also efficient in transfection.
Resumo:
Trypsin is a serino-protease with a polypeptide chain of 223 amino acid residues and contains six disulfide bridges. It is a globular protein with a predominance of antiparallel ß-sheet and helix in its secondary structure and has two domains with similar structures. We assessed the stability of ß-trypsin in the acid pH range using microcalorimetric (differential scanning calorimetry) techniques. Protein concentrations varied in the range of 0.05 to 2.30 mg/ml. Buffer solutions of 50.0 mM ß-alanine and 20.0 mM CaCl2 at different pH values (from 2.0 to 4.2) and concentrations of sorbitol (1.0 and 2.0 M), urea (0.5 M) or guanidinium hydrochloride (0.5 and 1.0 M) were used. The data suggest that we are studying the same conformational transition of the protein in all experimental situations using pH, sorbitol, urea and guanidinium hydrochloride as perturbing agents. The observed van't Hoff ratios (deltaHcal/deltaHvH) of 1.0 to 0.5 in the pH range of 3.2 to 4.2 suggest protein aggregation. In contrast, deltaHcal/deltaHvH ratios equal to one in the pH range of 2.0 to 3.2 suggest that the protein unfolds as a monomer. At pH 3.00, ß-trypsin unfolded with Tm = 54ºC and deltaH = 101.8 kcal/mol, and the change in heat capacity between the native and unfolded forms of the protein (deltaCp) was estimated to be 2.50 ± 0.07 kcal mol-1 K-1. The stability of ß-trypsin calculated at 298 K was deltaG D = 5.7 kcal/mol at pH 3.00 and deltaG D = 15.2 kcal/mol at pH 7.00, values in the range expected for a small globular protein.
Resumo:
Merisodassa tapahtunut muutos – erityisesti konevoiman syrjäyttäessä purjeet ja raudan korvatessa puumateriaalin 1800-luvun loppupuolella – johti nykypäivänäkin merkittäviin merisodan teoreettisiin tarkasteluihin. Teorioihin pohjautuneet merisotataidon yleisperiaatteet saivat ensimmäisen maailmansodan aikana käytännön testauksensa. Voittajat ja häviäjät analysoivat taistelut sekä maailmalla vallinneen ripeän teknisen kehityksen, minkä seurauksena laivastojen varustelu kiihtyi uudestaan valtapolitiikan tueksi. Maailmansotien välisenä aikana pyrittiin kansainvälisin sopimuksin säätelemään suurten laivastojen, kuten Britannian, Ranskan, Italian, Japanin ja Yhdysvaltojen varustelukilpailua. Versaillesin rauhansopimus rajoitti samanaikaisesti Saksan merivoimien kokoa. Tässä työssä tutkitaan Britannian ja Saksan merivoimien varustelua ja merisotataidon kehittymistä maailmansotien välisenä aikana. Merisotataidon kehittymisen tarkastelu tapahtuu postimerkkien avulla. Postimerkki syntyi Englannissa vuonna 1840 ja sen käyttö yleistyi ympäri maailman lähes samanaikaisesti konevoimaa käyttäneiden laivojen kanssa. Postimerkkien kuva-aiheet olivat aluksi valtioiden päämiehiä, heraldiikkaa, maisemia tai abstrakteja aiheita. Vasta 1900-luvun alkupuolella kuva-aiheina saattoi olla lähes mitä vain, myös sotalaivojen kuvia. Postimerkkikokoelmastani erottuu tutkimusaiheeseen 335 merkkiä. Britannian ja Saksan kansallisarkistojen alkuperäislähteiden ja tutkimuskirjallisuuden dokumenttianalyysiin perustuvaa merisotataidon moninaista kehitystä verrataan tutkimuksessani postimerkkien kuva-aiheisiin ja niiden yksityiskohtiin 3 300 kertaa. Tällä menettelyllä pyrin selvittämään voiko postimerkkejä käyttää ja pitää merisotaidon kehityksen kattavina dokumentteina. Postimerkeissä satunnaisiksi jääneet virheet tai propaganda eivät vähennä merisotataidon kehityksen kuvaamisen dokumenttiarvoa. Postimerkkien sotalaivoihin liittyvät kuvat kattavat muutamaa laivaluokkaa lukuunottamatta molempien maiden kaikki taistelualuslajit- ja luokat. Postimerkeistä voidaan nähdä vanhat sotalaivat, niiden peruskorjaukset ja uudet luokat lentotukialuksista sukellusveneisiin. Alusten kuvat voidaan liittää Britannian kansainyhteisön muuttuneisiin strategisiin ja taktisiin tavoitteisiin niin Atlantilla kuin Kaukoidässä. Saksan merivoimien nousu Versaillesin rauhanehtojen rajoituksista ja lopulta pyrkimys Britannian kauppamerenkulun tuhoajaksi välittyy myös postimerkeistä. Yleinen sotatekninen kehitys, lentoneiden tulo merisotanäyttämölle ja aikanaan kansainvälisten tonnistorajoitusten poistuminen näkyvät postimerkeissä. Kokopostimerkin historian aikana vuoteen 2012 mennessä purjeettomien, nykyaikaisten sotalaivojen kuvia on julkaistu noin 3 350 postimerkillä, jotka on koottu Maailman suurin laivasto-osasto -postimerkkikokoelmaani noin 35 vuoden aikana
Resumo:
Vertebrate hemoglobin, contained in erythrocytes, is a globular protein with a quaternary structure composed of 4 globin chains (2 alpha and 2 beta) and a prosthetic group named heme bound to each one. Having myoglobin as an ancestor, hemoglobin acquired the capacity to respond to chemical stimuli that modulate its function according to tissue requirements for oxygen. Fish are generally submitted to spatial and temporal O2 variations and have developed anatomical, physiological and biochemical strategies to adapt to the changing environmental gas availability. Structurally, most fish hemoglobins are tetrameric; however, those from some species such as lamprey and hagfish dissociate, being monomeric when oxygenated and oligomeric when deoxygenated. Fish blood frequently possesses several hemoglobins; the primary origin of this finding lies in the polymorphism that occurs in the globin loci, an aspect that may occasionally confer advantages to its carriers or even be a harmless evolutionary remnant. On the other hand, the functional properties exhibit different behaviors, ranging from a total absence of responses to allosteric regulation to drastic ones, such as the Root effect.
Resumo:
Laser cutting implementation possibilities into paper making machine was studied as the main objective of the work. Laser cutting technology application was considered as a replacement tool for conventional cutting methods used in paper making machines for longitudinal cutting such as edge trimming at different paper making process and tambour roll slitting. Laser cutting of paper was tested in 70’s for the first time. Since then, laser cutting and processing has been applied for paper materials with different level of success in industry. Laser cutting can be employed for longitudinal cutting of paper web in machine direction. The most common conventional cutting methods include water jet cutting and rotating slitting blades applied in paper making machines. Cutting with CO2 laser fulfils basic requirements for cutting quality, applicability to material and cutting speeds in all locations where longitudinal cutting is needed. Literature review provided description of advantages, disadvantages and challenges of laser technology when it was applied for cutting of paper material with particular attention to cutting of moving paper web. Based on studied laser cutting capabilities and problem definition of conventional cutting technologies, preliminary selection of the most promising application area was carried out. Laser cutting (trimming) of paper web edges in wet end was estimated to be the most promising area where it can be implemented. This assumption was made on the basis of rate of web breaks occurrence. It was found that up to 64 % of total number of web breaks occurred in wet end, particularly in location of so called open draws where paper web was transferred unsupported by wire or felt. Distribution of web breaks in machine cross direction revealed that defects of paper web edge was the main reason of tearing initiation and consequent web break. The assumption was made that laser cutting was capable of improvement of laser cut edge tensile strength due to high cutting quality and sealing effect of the edge after laser cutting. Studies of laser ablation of cellulose supported this claim. Linear energy needed for cutting was calculated with regard to paper web properties in intended laser cutting location. Calculated linear cutting energy was verified with series of laser cutting. Practically obtained laser energy needed for cutting deviated from calculated values. This could be explained by difference in heat transfer via radiation in laser cutting and different absorption characteristics of dry and moist paper material. Laser cut samples (both dry and moist (dry matter content about 25-40%)) were tested for strength properties. It was shown that tensile strength and strain break of laser cut samples are similar to corresponding values of non-laser cut samples. Chosen method, however, did not address tensile strength of laser cut edge in particular. Thus, the assumption of improving strength properties with laser cutting was not fully proved. Laser cutting effect on possible pollution of mill broke (recycling of trimmed edge) was carried out. Laser cut samples (both dry and moist) were tested on the content of dirt particles. The tests revealed that accumulation of dust particles on the surface of moist samples can take place. This has to be taken into account to prevent contamination of pulp suspension when trim waste is recycled. Material loss due to evaporation during laser cutting and amount of solid residues after cutting were evaluated. Edge trimming with laser would result in 0.25 kg/h of solid residues and 2.5 kg/h of lost material due to evaporation. Schemes of laser cutting implementation and needed laser equipment were discussed. Generally, laser cutting system would require two laser sources (one laser source for each cutting zone), set of beam transfer and focusing optics and cutting heads. In order to increase reliability of system, it was suggested that each laser source would have double capacity. That would allow to perform cutting employing one laser source working at full capacity for both cutting zones. Laser technology is in required level at the moment and do not require additional development. Moreover, capacity of speed increase is high due to availability high power laser sources what can support the tendency of speed increase of paper making machines. Laser cutting system would require special roll to maintain cutting. The scheme of such roll was proposed as well as roll integration into paper making machine. Laser cutting can be done in location of central roll in press section, before so-called open draw where many web breaks occur, where it has potential to improve runability of a paper making machine. Economic performance of laser cutting was done as comparison of laser cutting system and water jet cutting working in the same conditions. It was revealed that laser cutting would still be about two times more expensive compared to water jet cutting. This is mainly due to high investment cost of laser equipment and poor energy efficiency of CO2 lasers. Another factor is that laser cutting causes material loss due to evaporation whereas water jet cutting almost does not cause material loss. Despite difficulties of laser cutting implementation in paper making machine, its implementation can be beneficial. The crucial role in that is possibility to improve cut edge strength properties and consequently reduce number of web breaks. Capacity of laser cutting to maintain cutting speeds which exceed current speeds of paper making machines what is another argument to consider laser cutting technology in design of new high speed paper making machines.
Resumo:
The Brazil nut (Bertholletia excelsea H. B. K.) is noteworthy for its high content of lipids and proteins of elevated biological value and these factors justify the need for further research and incentives for the manufacturing of new trade products. In the present study we sought new forms of technological use of these nuts by the food industry, through their processing as flour, with no alteration in its energy content. The results after its elaboration showed a product with high energy value (431.48 kcal.100 g-1), protein content of 45.92 g.100 g-1, and fiber of 17.14%. The thermal analyses indicate that the introduction of another protein component, such as soy protein isolate, does not alter the reactions or thermal behavior. On the other hand, morphological analyses revealed granular structures similar to the structure of globular proteins. It was observed that after processing to obtain the flour, the product maintains its protein-energy content, as well as its characteristics when subjected to high temperatures.
Resumo:
The objective of this study was to determine the best lettuce cultivar (American 'Graciosa', 'Vanda', 'Marcela' and 'Lavínia') harvesting method. Therefore, quality and shelf-life were evaluated using sensory analyses. Lettuce heads was harvested with the root on by the producer, so that they were cut in different ways in the laboratory. The samples were stored in a cold chamber at 10 °C and 80% ± 2% of relative humidity for nine days, and the sensorial analyses were performed according to Qualitative Descriptive Analysis method on days 1, 3, 6, and 9 of storage by twelve trained testers. The results were evaluated by variance analysis, principal component analysis, and the Tukey test with a reliability of 95%. The results indicate that there was a reduction in the quality of lettuce between the 1st and the 5th day of storage and that after the sixth day of storage the lettuce samples were considered unfit for consumption, except for the 'Lavínia' lettuce cultivar with root and cut treatment 2. On the ninth day of storage all samples were considered inappropriate for consumption.
Resumo:
Marolo, also known as araticum or head-to-black, is a globular berry, a species native to the Brazilian savannah. The aim of this study was to evaluate the physical, chemical, and microbiological stability of frozen marolo pulp during 12 months of frozen storage. It was observed that the levels of ash (0.28-0.22%), protein (0.77-0.71%), lipids (1.75-1.73%), carbohydrates (12.1-10.15%), calorie (67.23-59.01 kcal), sucrose (2.50-1.29%), citric acid (435.63-197.5 µg.g-1), tartaric acid (4.38-1.88 µg.g-1) , acetic acid (470.38-279.25 µg.g-1), ascorbic acid (3.00-0.00 µg.g-1), total pectin (0.67-0.39%), pH (3.88-3.83), and b* chromaticity coordinates (24.85-20.53) decreased reduced during storage, whereas the levels of moisture (85.10-87.19%), color parameters (L* 58.89-62.62 and a* 5.37-7.86), reducing sugars (4.53-5.62%), total soluble sugars (7.1-7.36%), soluble solids (7.0-8.4 ºBrix), total acidity (0.9-1.0%), malic acid (514.13-781.25 µg.g-1), soluble pectin (0.16-0.24%), and antioxidant (6.85-37.35% of DPPH discoloration) increased over the one-year of storage period. According to the physical, chemical, and microbiological parameters assessed, the product can be stored for 12 months without loss of quality with addition of citric acid as a preservative.
Resumo:
The aim of the present study was to precool cauliflower using forced-air, vacuum and high and low flow hydro cooling methods. The weight of the precooled cauliflower heads (5000±5 g) was measured before they were placed in standard plastic crates. Cauliflower heads, whose initial temperature was 23.5 ± 0.5 ºC, were cooled until the temperature reached at 1 ºC. During the precooling process, time-dependent temperature and energy consumption were measured, and during vacuum precooling, the decreasing pressure values were recorded, and a curve of time-dependent pressure decrease (vacuum) was built. The most suitable cooling method to precool cauliflower in terms of cooling time and energy consumption was vacuum, followed by the high and low flow hydro and forced-air precooling methods, respectively. The highest weight loss was observed in the vacuum precooling method, followed by the forced-air method. However, there was an increase in the weight of the cauliflower heads in the high and low flow hydro precooling method. The best colour and hardness values were found in the vacuum precooling method. Among all methods tested, the most suitable method to precool cauliflower in terms of cooling and quality parameters was the vacuum precooling method.
Resumo:
Cauliflower heads, which were precooled using four different methods including vacuum, forced-air, and high and low flow hydro precooling, were stored under controlled atmosphere and room conditions. Controlled atmosphere conditions (CA) were as follows: 1°C temperature, 90 ± 5% relative humidity, and 0:21 [(%CO2:%O2) – (0:21) control] atmosphere composition. Room conditions (RC) were: 22±1°C temperature and 55-60% humidity. Various quality parameters of the cauliflower heads were assessed during storage (days 0, 7, 14, 21, 28, and 35) under controlled atmosphere and room conditions (days 0, 5, and 10). During storage, weight loss, deterioration rate, overall sensory quality score, hardness, and colour (L, a, b, C and α) were evaluated. In the present study, the strength and quality parameters of cauliflower under CA and RC conditions were obtained. Vacuum precooling was found to be most suitable method before cauliflower was submitted to cold storage and sent to market. Furthermore, the storage of cauliflower without precooling resulted in a significant decrease in quality parameters.
Multivariate study of Nile tilapia byproducts enriched with omega-3 and dried with different methods
Resumo:
Abstract The present work aimed at studying the effect of different drying methods applied to tilapia byproducts (heads, viscera and carcasses) fed with flaxseed, verifying the contents of omega-3 fatty acids. Two diets were given to the tilapia: a control and a flaxseed formulation, over the course of 60 days. After this period, they were slaughtered and their byproducts (heads, viscera and carcasses) were collected. These fish parts were analyzed in natura, lyophilized and oven dried. Byproducts from tilapia fed with flaxseed presented docosapentaenoic, eicopentaenoic and docosahexanoic fatty acids as a result of the enzymatic metabolism of the fish. The byproducts from the oven drying process had lower levels of polyunsaturated fatty acids. In the multivariate analysis, the byproducts from fish fed with flaxseed had a greater composition of fatty acids. The addition of flaxseed in fish diets, as well as the utilization of their byproducts, may become a good business strategy. Additionally, the byproducts may be dried to facilitate transport and storage.
Resumo:
Research about music instrument teacher education is scattered and fairly recent, especially in the European context. The purpose of this study was to explore two cases of piano teacher education programs at higher music education institutions, one in Finland, and one in Germany, to gain insights into the preparation of piano teachers for their professional working life. The aim was to identify issues for consideration in curriculum development of piano teacher education to enhance the teaching and learning of piano playing, and to ultimately increase musical practice and engagement among young learners. Nine semi-structured interviews with piano teacher educators, heads of program, other lecturers within the program, and student piano teachers in both cases were analyzed using applied thematic analysis. Three main themes with subcategories emerged: (1) the organization of the piano teacher education program, such as the structure, the content, the learning environments provided, and the development mechanisms of the program; (2) the views on the piano teacher profession, the working environment and resulting requirements, including further education during professional life; and (3) the professional skills and teacher identity development of student teachers. While the supposed working environments and requirements of future piano teachers, the student teachers' development characteristics, and the content were found reasonably concurrent in both cases, the structure of the teacher education program, and the organization of learning environments presented notable differences. While the complete teacher qualification in the Finnish case was offered as option in the Bachelor and Master of Music program within the piano department, the German case offered a separate program for music instrument educators. Other main differences concerned the organizations of practical teaching experiences, and the linking of practical with theoretical pedagogy. Conviction and enthusiasm for improving piano and other music instrument teacher education seemed remarkable. These improvements could include the development of a comprehensive teacher education pedagogy for music instrument teacher educators, intensified cross-linking within and of higher music education institutions in local contexts, and the expansion of professional development opportunities.
Resumo:
Raakamäntyöljy on selluteollisuuden sivutuote. Suopa erotetaan mustalipeästä ja palstoitetaan tuottaen siten raakamäntyöljyä. Raakamäntyöljy tislataan tavanomaisesti viiteen pääjakeeseen: rasvahapot, hartsihapot, mäntyöljytisle, esiöljy ja mäntyöljypiki. Näiden jakeiden lisäksi raakamäntyöljyssä on erityisesti mustalipeästä siihen erottuneita epäpuhtauksia, jotka haittaavat raakamäntyöljyn prosessointia. Epäpuhtauksia ovat orgaaniset ja epäorgaaniset yhdisteet, kuten metallit, suolat ja ligniini. Nämä epäpuhtaudet aiheuttavat haitallisia reaktioita prosessissa huonontaen siten lopputuotejakeiden laatua. Tämän lisäksi epäpuhtaudet aiheuttavat saostumia prosessilaitteissa alentaen siten prosessointitehokkuutta. Raakamäntyöljyn esikäsittelyllä tehostetaan tislauksen toimintaa. Työssä esitetään esikäsittelymenetelmistä mm. degumming-menetelmä, laimea happopesu, hiilidioksidikäsittely, valkaisu ja lämpökäsittely. Menetelmien pohjalta valitaan tätä työtä varten yksi menetelmä, jonka pohjalta suunnitellaan kokeellisessa osassa suoritettavat kokeet. Kokeellinen osuus koostuu esikokeista, varsinaisista kokeista ja lisäkokeista. Menetelmän tarkoituksena on saavuttaa epäpuhtauksille 90–95 % reduktioaste. Kokeiden onnistumista tutkitaan analysoimalla alkuperäinen raakamäntyöljy, sekä jokaisen kokeen jälkeen erotetut faasit. Työssä saavutettiin hyvä erotustehokkuus. Alkuperäisen tavoitteen mukaista reduktioastetta ei pystytty määrittämään eri analyysimenetelmien ja niiden analyysituloksissa ilmenneiden eroavaisuuksien vuoksi, mutta lisäkokeiden ansiosta pystyttiin vahvistamaan kyseisen koejärjestelmän optimaalinen poistoaste. Lisäksi työssä havaittiin että esikäsittelytulos on hyvin riippuvainen käsiteltävän raaka-aineen koostumuksesta.