Registrador portátil de odorantes basado en la modulación de temperatura de un sensor mos comercial

A simple, portable and low-cost system for odor detection was developed using a single MOS commercial sensor and a microcontroller. The temperature modulation technique was implemented applying a DC signal pulse to the sensor heater by a bipolar transistor. Two odorant profiles, ethanol and acetic acid vapors, were obtained and distinguished based on their amplitude versus time responses. Response for acetic acid was not reported by the sensor manufacturer. An ethanol vapor calibration curve was also obtained. Experimental data showed a potential behavior according to the theoretical equation of the MOS sensors. Values of logK=0.457 and α=-0.213 for a 95% confidence level were obtained.

Synthesis of 1H-benzoxazine-2,4-diones from heterocyclic anhydrides: evaluation of antioxidant and antimicrobial activities

A facile one-step synthesis of 1H-benzoxazine-2,4-diones from heterocyclic anhydrides and TMSA was described. This paper determines their antimicrobial activity against nine human bacterial pathogens by the broth microdilution method; antioxidant activity by DPPH• inactivation and a ferric-reducing power assay; and toxicity by a brine shrimp, Artemia salina, assay. The 1H-benzoxazine-2,4-dione yields were in the range of 57 to 98%. The novel compound 1H-pyrazino[2,3-][1,3]oxazine-2,4-dione 4c showed the highest antioxidant capacity (DPPH 35.4% and FRAP 0.063 µmol TEs/µmol).

A NOVEL POLYACRYLAMIDE-BASED HYDROGEL CROSSLINKED WITH CELLULOSE ACETATE AND PREPARED BY PRECIPITATION POLYMERIZATION

The synthesis of polyacrylamide-cellulose acetate hydrogels by precipitation polymerization in acetone solution is reported herein. These hydrogels exhibit smaller swelling ratios and larger compression moduli than homo polyacrylamide hydrogels. For cellulose acetate concentrations above 20 wt.%, hydrogels with N,N'-methylenebisacrylamide as a crosslinker exhibit swelling ratios and compression moduli similar to those of the hydrogels without the crosslinker. A possible explanation for this behavior is that cellulose acetate crosslinks polyacrylamide via free-radical reaction. The hydrogels obtained without the N,N'-methylenebisacrylamide crosslinker exhibit compression moduli up to 1.7 MPa, making them suitable for tissue engineering applications such as cartilage replacement.

Rotuun, etnisyyteen, luokkaan ja sukupuoleen kytkeytyvät valtasuhteet ja niiden problematisointi Julia Alvarezin romaanissa How the García Girls Lost Their Accents

Pro gradu -tutkielmani käsittelee valtasuhteita rotuun, etnisyyteen, luokkaan ja sukupuoleen kytkeytyvinä historiallisina verkostoina ja niiden vaikutuksia ihmisten elämään. Tutkielman kohdetekstinä on dominikaanilaisamerikkalaisen kirjailijan Julia Alvarezin (s. 1950) esikoisromaani How the García Girls Lost Their Accents (1991). Alvarezin romaani on omaelämäkerrallinen, ja se perustuu osittain historiallisiin tositapahtumiin. Tutkimusotteeni on kontekstualisoiva; teos asetetaan osaksi laajempia historiallisia tapahtumia ja niiden muodostamia valtahierarkioita. Teos sijoittuu päähenkilöiden kotimaan, Dominikaanisen tasavallan, lisäksi Yhdysvaltoihin, jonne Garcían perheen isä, äiti ja neljä tytärtä pakenevat diktaattori Trujillon tyranniaa 1960-luvulla. Tutkimukseni teoreettinen viitekehys nojaa postkoloniaaliseen ja feministiseen kirjallisuudentutkimukseen, joiden pyrkimyksenä on hegemonisten rakenteiden purkaminen. Valtasuhteiden dekonstruktiivisen paljastamisen avulla tuotettuja ja väärinkerrottuja historioita ja ruumiita kirjoitetaan uudelleen. Pohdin Alvarezin esikoisromaanin valtasuhteita esimerkiksi Michel Foucault’n vallan teoriaa hyödyntäen, mutta liitän analyysiin myös feminististä teoriaa etenkin Judith Butlerin ajatusten avulla. Tarkastelen työssäni romaanin henkilöhahmojen elämää ja identiteettien muodostumista rotuun, etnisyyteen, luokkaan ja sukupuoleen kytkeytyvän problemaattisen valtajaon näkökulmasta, jolla on juuri Karibian alueella vahvat historialliset erityispiirteensä kolonialismin sekä sen jälkivaikutusten runtelemana alueena. Työssäni tutkitaan muun muassa kolonialismin ja siirtolaisuuden diskursseissa päähenkilöiden elämään vaikuttavia valtasuhteita, ja etenkin kulttuuristen ja seksuaalisten identiteettien muodostumista marginalisoiduilla raja-alueilla. Osoitan, kuinka teoksesta käyvät ilmi erilaisten mutkikkaiden rotuun, etnisyyteen, luokkaan ja sukupuoleen liittyvien valtasuhteiden vaikutukset etenkin naisten elämään ja identiteetteihin. Mielestäni Alvarez tuo kerronnallaan ilmi valtasuhteiden kontekstisidonnaisuutta ja samalla niiden mielivaltaista ja rakenteellista luonnetta. Valta ja vallitsevat kaksijakoiset valtajärjestykset ovat tuotettuja ja toimivat yleensä poliittisesti jonkin ryhmän hyväksi toisia ryhmiä sortaen. Keskeinen tutkimustulos on, että Alvarezin teoksessa usein implisiittisesti kuvatut, kauas historiaan kytköksissä olevat valtasuhteet vaikuttavat monin tavoin teoksen päähenkilöiden elämään ja identiteettien muodostumiseen.

Karte von Amerika aus dem Jahre 1500 : entworfen von Juan de la Cosa : Begleiter des Columbus auf dessen zweiter Reise

Faksimile Juan de la Cosan kartasta vuodelta 1500

A chart of the southern part of South America : with the track of the centurion from the island of St. Catherines to the island of Juan Fernandes in which is inserted the variation and soundings observ'd on board her, together with her deviation from her estimated course in passing round Cap Horn, occasiond by the force of the currents / R. W. Seale sculp

Nimeketiedot nimiönkehyksissä

Aumento da vida útil e microbiologia da carne suína embalada em atmosfera modificada

Com o objetivo de avaliar o efeito da embalagem de carne suína em atmosfera modificada, obteve-se assepticamente amostras de lombo (Longissimus dorsi) de suíno de aproximadamente 3x3cm que depois de lavadas em solução salina (0,35%) estéril, foram introduzidas em bolsas de plástico (Cryovac BB4L) de baixa permeabilidade. Dividiram-se em 4 lotes e se embalaram com aproximadamente 1,0l de ar (100%), nitrogênio (100%), 20/80 e 40/60 CO2/O2 e se termo-selaram. Finalmente, cada lote se subdividiu em 2, armazenando-se a 1 e 7ºC. Durante o armazenamento tomaram-se amostras determinando-se a composição da atmosfera, o pH e a composição da microbiota (microbiota total, bactérias lácticas, Enterobacteriaceae, Brochothrix thermosphacta e contagens em ágar pseudomonas). Os parâmetros de crescimento (fase de latência e tempo de duplicação) dos microrganismos foram determinados mediante a equação de Gompertz. Os resultados demonstraram que a vida útil da carne suína é prolongada quando se armazena em atmosferas modificadas. As atmosferas enriquecidas com CO2 e a 1ºC mostraram uma maior eficácia. As atmosferas com CO2, mantiveram o pH das amostras constante durante todo o período de armazenamento. A 1 e 7ºC, as fases de latência e os tempos de duplicação da microbiota total foram progressivamente maiores na seguinte ordem: atmosfera de ar (100%), N2 (100%), 20/80 e 40/60 CO2/O2. Pode-se concluir que, tanto a 1 como a 7ºC, a utilização das atmosferas modificadas retardou o crescimento das bactérias alterantes da carne suína, favorecendo o prolongamento da vida útil, principalmente nas atmosferas com CO2.

Daños tóxicos en tejidos vegetales, producidos por aguas contaminadas con arsénico en Zimapán, Hidalgo, México

Según estudios realizados en el periodo de 1992-1998 en las aguas de los pozos, norias y manantiales, del municipio de Zimapán, Estado de Hidalgo, México, se corroboró que existía un incremento en el contenido de arsénico rebasando los límites máximos permisibles por la Norma Oficial Mexicana. La determinación de arsénico en las muestras de aguas se realizó por absorción atómica (AAS), mediante generador de hidruros (GH). En este estudio se utilizó el Vicia faba como un bioensayo para evaluar el daño genotóxico con la prueba de inducción de micronúcleos por exposición al agua de Zimapán, contaminada con As en células de raíces. Se utilizó como ensayo de control un agua de pozo de similares características del municipio de Pachuca, pero con contenidos de As por debajo de los límites de detección. Los resultados mostraron que el agua de esta región presenta altas concentraciones de arsénico y que puede provocar efectos genotóxicos que se manifiestan por la inducción de micronúcleos en las células meristemáticas de raíces de tejidos vegetales sensible.

Influence of chitosan addition on quality properties of vacuum-packaged pork sausages

The aim of the study was to evaluate the influence of the chitosan addition on the quality of vacuum packaged pork sausages. A variant of the product was elaborated with 1% (w/w) of chitosan in lactic acid solution at 1% (v/v) and it was compared to a control. Sausages were mechanically stuffed and manually conformed and vacuum packaged. Sausages were stored at 4 °C and microbiological evaluations, pH measurements, texture profile analysis and sensorial evaluation were performed. The chitosan addition in the formulation of the sausages did not reduce the microbiological counts. The pH values obtained in all samples were similar, which suggests that the chitosan addition did not influence the pH values of sausages. The added chitosan did not affect significantly (p < 0.05) the results of the texture profile analysis and sensorial attributes and therefore, the overall acceptance of the sausages.

Influence of physical damage and freezing on histamine concentration and microbiological quality of yellowfin tuna during processing

Yellowfin tuna has a high level of free histidine in their muscle, which can lead to histamine formation by microorganisms if temperature abuse occurs during handling and further processing. The objective of this study was to measure levels of histamine in damaged and undamaged thawed muscle to determine the effect of physical damage on the microbial count and histamine formation during the initial steps of canning processing and to isolate and identify the main histamine-forming microorganisms present in the flesh of yellowfin tuna. Total mesophilic and psicrophilic microorganisms were determined using the standard plate method. The presence of histamine-forming microorganisms was determined in a modified Niven's agar. Strains were further identified using the API 20E kit for enterobacteriaceae and Gram-negative bacilli. Physically damaged tuna did not show higher microbiological contamination than that of undamaged muscle tuna. The most active histamine-forming microorganism present in tuna flesh was Morganella morganii. Other decarboxylating microorganisms present were Enterobacter agglomerans and Enterobacter cloacae. Physical damage of tune during catching and handling did not increase the level of histamine or the amount of microorganisms present in tuna meat during frozen transportation, but they showed a higher risk of histamine-forming microorganism growth during processing.

La transformación de la doctrina de la virtud moral en el pensamiento de Juan Duns Escoto

En su comentario a la distinción 33 del Tercer Libro de las Sentencias, Juan Duns Escoto desarrolla su doctrina referida al sujeto de las virtudes morales, mediante la cual establece la voluntad como única sede posible de las mismas. En el presente trabajo se intentará mostrar que esta determinación, por un lado, es consecuencia de la previa postulación de la voluntad como única potencia moral del hombre y que, por otro, implica una fuerte debilitamiento del rol e importancia de la virtud para la perfección moral.