Roughing it /

Mode of access: Internet.

Roughing it in Siberia, with some account of the Trans-Siberian railway, and the gold-mining industry of Asiatic Russia,

Mode of access: Internet.

Astringent Food Compounds and Their Interactions with Taste Properties

Astringency is traditionally thought to be induced by plant tannins in foods. Because of this current research concerning the mechanism of astringency is focused on tannin‐protein interactions and thus on precipitation, which may be perceived by mechanoreceptors. However, astringency is elicited by a wide range of different phenolic compounds, as well as, some non‐phenolic compounds in various foods. Many ellagitannins or smaller compounds that contribute to astringent properties do not interact with salivary proteins and may be directly perceived through some receptors. Generally, the higher degree of polymerization of proanthocyanidins can be associated with more intense astringency. However, the astringent properties of smaller phenolic compounds may not be directly predicted from the structure of a compound, although glycosylation has a significant role. The astringency of organic acids may be directly linked to the perception of sourness, and this increases along with decreasing pH. Astringency can be divided into different sub‐qualities, including even other qualities than traditional mouth‐drying, puckering or roughing sensations. Astringency is often accompanied by bitter or sour or both taste properties. The different sub‐qualities can be influenced by different astringent compounds. In general, the glycolysation of the phenolic compound results in more velvety and smooth mouthdrying astringency. Flavonol glycosides and other flavonoid compounds and ellagitannins contribute to this velvety mouthdrying astringency. Additionally, they often lack the bitter properties. Proanthocyanidins and phenolic acids elicit more puckering and roughing astringency with some additional bitter properties. Quercetin 3‐O‐rutinoside, along with other quercetin glycosides, is among the key astringent compounds in black tea and red currants. In foods, there are always various other additional attributes that are perceived at the same with astringency. Astringent compounds themselves may have other sensory characteristics, such as bitter or sour properties, or they may enhance or suppress other sensory properties. Components contributing to these other properties, such as sugars, may also have similar effects on astringent sensations. Food components eliciting sweetness or fattiness or some polymeric polysaccharides can be used to mask astringent subqualities. Astringency can generally be referred to as a negative contributor to the liking of various foods. On the other hand, perceptions of astringent properties can vary among individuals. Many genetic factors that influence perceptions of taste properties, such as variations in perceiving a bitter taste or variations in saliva, may also effect the perception of astringency. Individuals who are more sensitive to different sensations may notice the differences between astringent properties more clearly. This may not have effects on the overall perception of astringency. However, in many cases, the liking of astringent foods may need to be learned by repetitive exposure. Astringency is often among the key sensory properties forming the unique overall flavour of certain foods, and therefore it also influences whether or not a food is liked. In many cases, astringency may be an important sub‐property suppressed by other more abundant sensory properties, but it may still have a significant contribution to the overall flavour and thus consumer preferences. The results of the practical work of this thesis show that the astringent phenolic compounds are mostly located in the skin fractions of black currants, crowberries and bilberries (publications I–III). The skin fractions themselves are rather tasteless. However, the astringent phenolic compounds can be efficiently removed from these skin fractions by consecutive ethanol extractions. Berries contain a wide range of different flavonol glycosides, hydroxycinnamic acid derivatives and anthocyanins and some of them strongly contribute to the different astringent and bitterness properties. Sweetness and sourness are located in the juice fractions along with the majority of sugars and fruit acids. The sweet and sour properties of the juice may be used to mask the astringent and bitterness properties of the extracts. Enzymatic treatments increase the astringent properties and fermented flavour of the black currant juice and decrease sweetness and freshness due to the effects on chemical compositions (IV). Sourness and sweetness are positive contributors to the liking of crowberry and bilberry fractions, whereas bitterness is more negative (V). Some astringent properties in berries are clearly negative factors, whereas some may be more positive. The liking of berries is strongly influenced by various consumer background factors, such as motives and health concerns. The liking of berries and berry fractions may also be affected by genetic factors, such as variations in the gene hTAS2R38, which codes bitter taste receptors (V).

Influence of duty factor on the die-sinking Electrical Discharge Machining of high-strength aluminum alloy under rough machining

The use of high-strength aluminium alloys as material for injection molding tools to produce small and medium batches of plastic products as well as prototyping molds is becoming of increasing demand by the tooling industry. These alloys are replacing the traditional use of steel in the cases above because they offer many advantages such as very high thermal conductivity associated with good corrosion and wear resistance presenting good machinability in milling and electrical discharge machining operations. Unfortunately there is little technological knowledge on the Electrical Discharge Machining (EDM) of high-strength aluminium alloys, especially about the AMP 8000 alloy. The duty factor, which means the ratio between pulse duration and pulse cycle time exerts an important role on the performance of EDM. This work has carried out an experimental study on the variation of the duty factor in order to analyze its influence on material removal rate and volumetric relative wear under roughing conditions of EDM process. The results showed that high values of duty factor are possible to be applied without bringing instability into the EDM process and with improvement of material removal rate and volumetric relative wear.

Effects of milling condition on the surface integrity of hot forged steel

This paper presents a study on the influence of milling condition on workpiece surface integrity focusing on hardness and roughness. The experimental work was carried out on a CNC machining center considering roughing and finishing operations. A 25 mm diameter endmill with two cemented carbide inserts coated with TiN layer were used for end milling operation. Low carbon alloyed steel Cr-Mo forged at 1200 degrees C was used as workpiece on the tests. Two kinds of workpiece conditions were considered, i.e. cur cooled after hot forging and normalized at 950 degrees C for 2 h. The results showed that finishing operation was able to significantly decrease the roughness by at least 46% without changing the hardness. on the other hand, roughing operation caused an increase in hardness statistically significant by about 6%. The machined surface presented deformed regions within feed marks, which directly affected the roughness. Surface finish behavior seems to correlate to the chip ratio given the decrease of 25% for roughing condition, which damaged the chip formation. The material removal rate for finishing operation 41% greater than roughing condition demonstrated to be favorable to the heat dissipation and minimized the effect on material hardness.

Análise do processo de lixamento tubular da madeira de Corymbia citriodora

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Medição e análise do acabamento superficial da madeira de eucalipto na usinagem de torneamento cilínrico e lixamento

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo do fresamento de madeiras em centro de usinagem CNC

The lack of research related to wood machining processes, including the milling, as well as the increased use of this material in the industrial sector, it creates a need to increase research involving these processes, as the sector is in full technological and environmental remodeling. This paper studies the process of milling wood, presenting an analysis of the effects of cutting speed on surface quality by measuring roughness. We used a forward speed three cutting speeds, two species of wood (Pinus elliottii and Eucalyptus grandis) and two milling tools (roughing and finishing) machined by milling concordant and discordant. Each condition was repeated six times, and the measurements were performed in the opposite direction and in favor of cutting tool, generating results of the parameters Ra (average roughness) totaling 144 trials with it. These results were statistically analyzed using analysis of variance and Tukey test. Finally it was concluded that there are significant differences between the results of varying roughness when cutting speeds, milling and types of machining types tested

A influência do tamanho de grão ferrítico da peça na integridade superficial de peças erodidas

Pós-graduação em Engenharia Mecânica - FEIS

Das Paläolithikum der Magdalenahöhle bei Gerolstein

Die vorliegende Arbeit hat das von 1969 – 1972 ergrabene Inventar der Magdalenahöhle bei Gerolstein unter kritischer Berücksichtigung der Originaldokumentation sowie der stratigraphischen und sedimentologischen Beschreibungen erneut untersucht und v.a. hinsichtlich zweier Arbeitshypothesen überprüft. Daneben fanden jedoch auch die Schmuckobjekte und in kursorischer Weise die Tierknochen Betrachtung. Die Elfenbeinobjekte setzen sich aus elf Fragmenten zusammen, die bereits in zerbrochenem Zustand in die Höhle gelangt sein müssen. Sie sind mit mehreren Linienbündeln verziert, die teilweise aus v- oder zickzack-förmigen Motiven bestehen. Auch gestanzte Punktreihen treten auf. In ihrer Größe und Form sind die Elfenbeinobjekte einzigartig. Lediglich aus der Csákvár-Höhle in Ungarn gibt es vergleichbare Stücke, deren genaue Altersstellung jedoch unklar ist. Daneben kommen in der Magdalenahöhle zwei vollständige durchlochte Hirschgrandeln sowie die Fragmente einer durchlochten Grandel sowie eines durchlochten Wolfzahns vor. Diese tragen teilweise Spuren einer Aufhängung bzw. Befestigung. Der Grund für ihre Niederlegung vor Ort ist indes nicht endgültig zu klären. Die überlieferten Tierknochen besitzen verschiedene Grade von Verfärbung und Erhaltung, lassen sich dadurch jedoch nicht verschiedenen Schichten zuordnen. Neben Modifikationen von Carnivoren, darunter v.a. durch Verdauungsprozesse, sind auch an einigen Exemplaren Schnittspuren festgestellt worden. Eine Bärenphalange aus der Fundschicht b1 eröffnet so die Perspektive, die menschliche Belegung erneut mit der Radiokohlenstoffmethode direkt zu datieren. Der Untere paläolithische Fundhorizont besteht aus relativ unspezifischen Quarzartefakten, die von einer opportunistischen Abschlags- und Werkzeugsgewinnung aus lokalen Schottern zeugen. Für den Oberen paläolithischen Fundhorizont zeigt die Steinartefaktanalyse, dass die Abschläge als Herstellungsreste dünner bifazieller Geräte angesprochen werden können. Während dieser Befund alleine auch im Zusammenhang mit den spätmittelpaläolithischen Blattspitzengruppen gesehen werden kann, sprechen die bereits erwähnten vergesellschafteten Schmuckobjekte, der Nachweis eines Klingenabbaus sowie die fast ausschließliche Verwendung exogenen Rohmaterials für einen jungpaläolithischen Kontext, d.h. für eine Affinität zum Solutréen. Die Steinartefakte der Magdalenahöhle zeugen gleichzeitig von einer sehr mobilen Lebensweise, da lediglich eine Phase des Herstellungsprozesses des bifaziellen Geräts vor Ort stattgefunden hat. Gleichzeitig wurden früher an anderem Ort gewonnene Abschläge mitgebracht und als Werkzeug verwendet. Ebenso wie der Kern selbst wurden Abschläge auch wieder abtransportiert. Insgesamt kann daher eine Rohmaterial konservierende Strategie rekonstruiert werden, in der neben dem Kern als Gerät selbst auch die Abschläge Verwendung finden. Da die Magdalenahöhle als östlicher Niederschlag des Solutréen und als Beleg für das maximale Verbreitungsgebiet dieses Technokomplexes gewertet werden muss, reiht sie sich in eine Reihe von Fundstellen und Argumenten ein, wonach das zentrale Mitteleuropa während des LGM s.l. nicht menschenleer war, sondern in sporadischen Exkursionen begangen wurde. Obwohl sich daran noch keine dauerhafte Wiederbesiedlung anschloss, muss vom Bild einer absoluten Siedlungsleere Abstand genommen werden. Weitere Fundstellen und absolutchronologische Datierungen, u.a. der Magdalenahöhle, könnten in Zukunft zu einem noch besseren Verständnis der menschlichen Anpassungsstragien an kaltzeitliche Umwelten beitragen.

Transductive neurofuzzy-based torque control of a milling process: results of a case study

This paper presents the design and implementation of an intelligent control system based on local neurofuzzy models of the milling process relayed through an Ehternet-based application. Its purpose is to control the spindle torque of a milling process by using an internal model control paradigm to modify the feed rate in real time. The stabilization of cutting cutting torque is especially necessary in milling processes such as high-spedd roughing of steel moulds and dies tha present minor geometric uncertainties. Thus, maintenance of the curring torque increaes the material removal rate and reduces the risk of damage due to excessive spindle vibration, a very sensitive and expensive component in all high-speed milling machines. Torque control is therefore an interesting challenge from an industrial point of view.

The writings of Mark Twain [pseud.]

Each vol. has general half-title and special t.-p.

The complete works of Mark Twain.

v.1. The adventures of Tom Sawyer -- v.2. The innocents abroad -- v.3. Pudd'nhead Wilson -- v.4. The America claimant -- v.5. A Connecticut Yankee in King Arthur's court -- v.6. Roughing it -- v.7. Life on the Mississippi -- v.8. The mysterious stranger -- v.9. The adventures of Huckleberry Finn -- v.10. The gilded age -- v.11. A tramp abroad -- v.12. What is man? -- v.13. Following the equator -- v.14. Tom Sawyer abroad -- v.15. The man that corrupted Hadleyburg -- v.16. In defense of Harriet Shelley -- v.17. Joan of Arc -- v.18. The $30,000 bequest -- v.19. Sketches old and new -- v.20. Europe and elsewhere -- v.21. The prince and the pauper -- v.22. Mark Twain's notebook -- v.23. Christian science -- v.24. Mark Twain's speeches.

The writings of Mark Twain.

URL additional copies of v.6 and 19: Hillcrest Edition.