Relaciones nitr��geno-potasio en fertirriego para el cultivo protegido del tomate en suelo Ferral��tico Rojo

El objetivo del presente trabajo fue evaluar el efecto de soluciones nutritivas en el fertirriego, con diferentes relaciones entre el nitr��geno y el potasio, en la productividad y calidad de los frutos del tomate (h��brido Hazera 3019), en suelo Ferral��tico Rojo. La experiencia se desarroll�� en el Instituto de Investigaciones Hort��colas Liliana Dimitrova (La Habana, Cuba). Se estudiaron cuatro soluciones nutritivas, que se diferenciaron en su relaci��n NO3-+NH4+/K+ en t��rminos de meq L-1 (N/K), con una relaci��n K+/Ca2++Mg2+ en todas las variantes de 0,75. Los tratamientos resultantes (T1, 1:0,45; T2, 1:0,60 o testigo de producci��n, T3, 1:0,75 y T4, 1:0,90) fueron distribuidos en un dise��o completamente aleatorizado con cuatro r��plicas. La variaci��n de la relaci��n N/K en la soluci��n nutritiva influy�� en el rendimiento, la calidad externa y la vida en anaquel de los frutos de tomate, sin afectar la calidad bromatol��gica. La mejor combinaci��n entre estructura del rendimiento y calidad de los frutos se obtiene con la relaci��n N/K 1:0,75, al presentar rendimientos superiores en las categor��as de calidad comercial extra, primera y extra m��s primera, as�� como frutos con mayor firmeza y grosor del endocarpio, menor porcentaje de frutos fuera de norma y valores inferiores de p��rdidas postcosecha.

Din��mica de nutrientes na solu����o do solo em pomar fertirrigado de citros

O objetivo deste trabalho foi avaliar a din��mica de nutrientes na solu����o do solo ap��s a aplica����o, via fertirriga����o, de nitrog��nio, f��sforo e pot��ssio a laranjeiras. O experimento foi realizado entre setembro de 2007 e outubro de 2009, em pomares de laranjeiras 'Val��ncia' e 'Hamlin', enxertadas sobre citrumeleiro 'Swingle'. Foram avaliadas cinco doses de N, P2O5 e K2O (0, 25, 50, 100 e 200% da dose recomendada). A solu����o do solo foi extra��da a 30 e 60 cm de profundidade, com o aux��lio de extratores com c��psulas porosas. Foram realizadas 11 avalia����es durante o per��odo experimental, com as extra����es iniciadas ap��s 12 horas das fertirriga����es. O aumento das doses reduziu o pH (pH~3,5, na maior dose), e aumentou a condutividade el��trica (CE~1,5 dS m-1, na maior dose) e os teores de NH4, NO3, P, K, Mn e Zn na solu����o do solo, nas duas profundidades amostradas. Nos meses com maior precipita����o pluvial, houve perda potencial de nutrientes por lixivia����o, pois maiores concentra����es de NO3, K e B foram observadas �� profundidade de 60 cm. A an��lise da solu����o do solo, obtida por extratores com c��psula de cer��mica porosa, pode ser considerada ferramenta auxiliar para monitorar e avaliar a disponibilidade de nutrientes ��s plantas.

Kromatografisen erotusfaasin huokoskoon karakterisointi

Ty��ss�� tutkittiin sulfonoitujen polystyreenidivinyylibentseenirunkoisten geeli-, meso- ja makrohuokoistenioninvaihtohartsien rakennetta k��ytt��en useita eri karakterisointimenetelmi��. Lis��ksi ty��ss�� tutkittiin hartsien huokoskoon vaikutusta aminohappojen kromatografisessa erotuksessa. Ty��n p����paino oli hartsien huokoskoon ja huokoisuuden m����ritt��misess��. Sen selvitt��miseksi k��ytettiin hyv��ksi elektronimikroskopiaa, typpiadsorptiomittauksia, sek�� k����nteist�� kokoekskluusiokromatografiaa. Parhaat tulokset saatiin k����nteisell�� kokoekskluusiokromatografialla, joka perustuu erikokoisten dekstraanipolymeerien k��ytt����n mallimolekyylein��. Menetelm�� sopii meso- ja makrohuokoisuuden tutkimiseen, mutta sen heikkoutena on eritt��in pitk�� mittausaika. Menetelm�� antaa my��s huokoskokojakauman, mutta yhden hartsin mittaaminen voi kest���� viikon. Menetelm���� muutettiin siten, ett�� k��ytettiin m����ritett��v���� huokoskokoaluetta kuvaavien kahden dekstraanipolymeerin seosta. Kromatografiset ajo-olosuhteet optimoitiin sellaisiksi, ett�� injektoidussa seoksessa olevien dekstraanien vastehuiput erottuivat toisistaan. T��ll��in voitiin luotettavasti m����ritt���� tutkittavan stationaarifaasin suhteellinen huokoisuus. T��t�� ty��ss�� kehitetty�� nopeaa k����nteiseen kokoekskluusiokromatografiaan perustuvaa menetelm���� kutsutaan kaksipistemenetelm��ksi. Hartsien sulfonihapporyhmien m����r���� ja jakautumista tutkittiin m����ritt��m��ll�� hartsien kationinvaihtokapasiteetti sek�� tutkimalla hartsin pintaa konfokaali-Raman-spektroskopian avulla. Sulfonihapporyhmien ioninvaihtokyvyn selvitt��miseksi mitattiin K+-muotoon muutetusta hartsista S/K-suhde poikkileikkauspinnasta. Tulosten perusteella hartsit olivat tasaisesti sulfonoituneet ja 95 % rikkiatomeista oli toimivassa ioninvaihtoryhm��ss��. Aminohappojen erotuksessa malliaineina oli lysiini, seriini ja tryptofaani. Hartsi oli NH4+-muodossa ja petitilavuus oli 91 mL. Eluenttina k��ytettiin vett��, jonka pH oli 10. Paras tulos saatiin virtausnopeudella 0,1 mL/min, jolla kaikki kolme aminohappoa erottuivat toisistaan Finex Oy:n mesohuokoisella KEF78-hartsilla. Muilla tutkituilla hartseilla kaikki kolme aminohappoa eiv��t miss����n ajo-olosuhteissa erottuneet t��ysin.

Din��mica de ��ons e acidifica����o do solo nos sistemas de fertirriga����o e aduba����o s��lida na citricultura

A experi��ncia em fertirriga����o na citricultura mundial est�� localizada em clima mediterr��nico, geralmente em solos alcalinos, nos quais a acidifica����o �� apontada como uma das vantagens dessa t��cnica. Por outro lado, nas condi����es de solos tropicais, a acidifica����o tem sido um ponto de estrangulamento, pois poder�� comprometer a sustentabilidade do sistema de fertirriga����o. Este trabalho foi elaborado com objetivo de avaliar a din��mica de ��ons no perfil do solo, quantificar as perdas de nutrientes por lixivia����o e seus efeitos sobre a acidifica����o do solo em diferentes sistemas de manejo com aduba����o s��lida e fertirriga����o. O experimento foi instalado em um Argissolo Vermelho-Amarelo distr��fico, na cidade de Piraju�� - SP, em um talh��o de variedade Natal sobre lim��o Cravo, com quatro anos de idade. Os tratamentos foram constitu��dos por duas doses de nutrientes (200; 40 e 160 kg ha-1, respectivamente de N, P2O5 e K2O e sua metade) e tr��s formas de aplica����o (aduba����o s��lida sem irriga����o, aduba����o s��lida irrigada e fertirriga����o), totalizando seis tratamentos. A din��mica de ��ons no solo foi monitorada pela amostragem do solo, nas profundidades de 0-20; 20-40 e 40-60 cm e tamb��m pela coleta da solu����o do solo, por meio de extratores de solu����o colocados em todas as parcelas, nas profundidades de 30 e 60 cm, durante tr��s anos. As maiores concentra����es de ��ons na solu����o do solo ocorreram nos tratamentos fertirrigados; conseq��entemente, estes tratamentos foram os que apresentaram maiores valores de condutividade el��trica. Teores elevados de N-NH4 e N- NO3 na solu����o do solo foram observados nos tratamentos fertirrigados, nas duas profundidades, mostrando que existe grande potencial de perda de nitrog��nio por lixivia����o. Essas perdas de nutrientes por lixivia����o, observadas nos tratamentos fertirrigados, com conseq��ente acidifica����o do solo, podem acarretar em restri����es ao uso da t��cnica de fertirriga����o em solos tropicais.

Ammoniakin talteenottoprosessin kehitys

Diplomity��ss�� kehitettiin ioninvaihtoon perustuva ammoniakin talteenottoprosessi NSSC (Neutral Sulphite Semi Chemical) -prosessin haihduttamon lauhteille. Tarkoituksena oli saada aallotuskartonkitehtaan kemi-kaalikiertoa suljettua ja sit�� kautta ammoniakkip����st��j�� v��hennetty��. Ammoniakki tuli ottaa hy��tymuodossa (ammoniakkih��yry tai ammoniumsulfiitti) talteen. Ammoniumsulfiittiliuosta k��ytet����n NSSC-prosessissa keittonesteen��. Kirjallisuusosassa selvitet����n strippaukseen perustuvia ammoniakin talteenottomahdollisuuksia. Tutkitaan ioninvaihdon teoriaa ja ammoniumin talteenottoon sopivien ioninvaihtomateriaalien ominaisuuksia ioninvaihtajina. Lis��ksi esitet����n ioninvaihtoprosesseihin liittyvi�� laitteistoratkaisuja ja prosessiolosuhteita. Ty��n kokeellisessa osassa on yleiskuvaus Powerflute Oy Savon Sellun prosesseista ja selvitet����n ammoniakin merkityst�� tehtaalle. Laboratoriokokein tutkittiin orgaanisten kationihartsien sek�� ep��orgaanisen luonnon zeoliitin soveltuvuutta ammoniumionien vaihtoon esihaihduttamon lauhteesta. Ammoniakin talteenottoprosessin toimivuutta teollisessa mittakaavassa selvitettiin rakennetulla pilotlaitteistolla suoritettujen kokeiden avulla. Lopuksi tehtiin ammoniakin talteenottoprosessin scale-up: laskettiin prosessin talteenottokapasiteetti, arvioitiin kustannuksia sek�� annettiin lausunto prosessin toteutettavuudesta. Laboratoriokokeiden perusteella luonnon zeoliitti ja heikosti hapan ioninvaihtohartsi eiv��t sovellu ammoniumionien vaihtoon NSSC haihduttamon lauhteista. Vahvasti hapan kationihartsi toimi ammoniumin talteenotossa parhaiten, joten se valittiin pilotkokeiden ioninvaihtomateriaaliksi. Pilotkokeissa ioninvaihtomateriaaliin saatiin sidottua ammoniumia noin 30 g NH4+ / dm3 hartsia, kun materiaalin teoreettinen ioninvaihtokapasiteetti oli 32 g NH4+ / dm3 hartsia. Ammoniumin l��p��isyk��yrien muotoon vaikutti suuresti sy��tt��lauhteen virtausnopeus ja ammoniumpitoisuus. Ioninvaihtomateriaalipedin syvyydell�� ei ollut niink����n merkityst��. Pilotkokeiden regenerointitavoista tehokkaimmaksi osoittautui h��yrystrippaus, jossa saavutettiin noin 90 %:n talteenottotehokkuus. Rikkihapokek��sittelyll�� talteenottotehokkuus j��i 50 %:iin. Teollisen mittakaavan laitoksella voidaan vuosittain regenerointitavasta riippuen ottaa talteen esihaihdut-tamon lauhteesta noin 100-150 tonnia ammoniakkia. Prosessin k��ytt��kustannukset ovat talteenotetusta ammoniakista saataviin s����st��ihin verrattuna suuret ja niihin vaikuttaa merkitt��v��sti ioninvaihtohartsin k��ytt��ik�� sek�� regenerointikemikaalien kulutus. Osittaisella kemikaalikierron sulkemisella saavutetaan NSSC-prosessissa sekund����rietuja, joiden vaikutuksen merkitt��vyys pit��isi tarkentaa lis��tutkimuksilla.

Recupera����o de metais de catalisadores usados de hidrotratamento (NiMo E CoMo/AL2O3)

This work presents a detailed study of the leaching behavior of deactivated hydrotreating catalysts (CoMo, NiMo/Al2O3) in presence of oxalate and NH4+ ions in various media. The yield of metals recovery may be optimized by adjusting several experimental parameters (time, temperature, etc). Leaching is limited by physical factors (diffusional effects caused by coke) and by the existence of silicate/spinel-like species which are poorly soluble in leaching solutions. Coke may be eliminated by an oxidation step at temperatures between 300-400��C. Above 400��C, solubilization of Ni and Co is drastically reduced. 50-90% wt of sulphate species and 15-30% wt of phosphate ions are solubilized during leaching. Silicon (as SiO2) is not solubilized. The best Ni-Co-Mo recoveries are in the 70-90% wt range; Fe recovery may be quantitative, whereas Al leaching may be lower than 5% wt.

Avalia����o da capacidade tamponante - um experimento participativo

The aim of this work is to show an experiment from which students can learn some of the main characteristics of buffer solutions. A mixture of some acid-base indicators, named as Yamada's indicator, can be used to estimate pH values in an acid-base titration of a buffer, with good approximation. In the experiment it is also possible to verify the relationship between the buffer capacity and the concentrations and the molar ratio of the components of a NH3 / NH4+ buffer solution. The shortage of experiments associated with the relative small importance given to many aspects of buffer solutions, is now explored with simplicity. In the proposed experiments, students prepare buffer solutions by themselves, calculate the pH, understand how acid-base indicators act and learn how buffer solutions work through graph constructed by sharing experimental data.

Fotocat��lise eletroqu��mica de atrazina sobre di��xido de tit��nio: efeito de diferentes par��metros experimentais

The atrazine photoelectrochemical degradation has been examined in solutions containing TiO2 on immobilized films under a variety of experimental conditions. It was possible to observe that the supporting electrolyte nature affects the intensity of the photocurrent, being an indicative of the adsorption process. The disappearance of the organic molecule follows approximately a pseudo-first order kinetic. As mineralization product, NH4+ and NO3- ion have been identified. These results indicated that the formation of NH4+ ion can be associated to the effect of atrazine adsorption, due to need of potential adaptation together with a variation in the supporting electrolyte concentration.

Composi����o qu��mica da precipita����o atmosf��rica no sul do Brasil: estudo preliminar

The present work is a preliminary study of total and wet precipitation in the Candiota region, RS. The samples were collected from January to June 2001 at four different sites. The following variables were analysed: pH, conductivity, alkalinity, Cl-, NO3-, F-, SO4(2-), Na+, K+, Mg2+, NH4+, Ca2+ and Zn, Cu, Fe, Al, Mn. The results showed slightly acidic precipitation and higher concentrations of NH4+, Na+, Cl- and SO4(2-). Factor analysis applied to the variables studied allowed identifying the major sources. Na+, Cl- and Mg2+ have their origin in sea salts and NH4+, Ca2+, K+, SO4(2-) and NO3- are from local anthropogenic sources.

Geoqu��mica das ��guas da bacia hidrogr��fica do Rio Descoberto, Bras��lia/DF - Brasil

The objective of this paper is to investigate the physical and chemical quality of the water of the Descoberto River during the dry and rainy seasons by measuring pH, temperature, electric conductivity, total dissolved solids, turbidity, color, alkalinity and NO3-, SO4(2-), PO4(3-), NH4+, Cl- and HCO3-, and the elements Sr, Mo, Cd, Y, Ti, Ca, V, Mg, Fe, Si, Ni, Zr, Cu, Al, Cr, Mn, Ba, Co, Zn, P, Na and K. The results showed high concentrations in both seasons, with dilution along the course of the river, minimizing for a while problems that compromise the quality of the water of this source. However, a progressive deterioration can occur due to an increase in the discharge of pollutants, resulting from population growth, agricultural activities and other factors.

Determina����o das formas de nitrog��nio e nitrog��nio total em rochas-reservat��rio de petr��leo por destila����o com arraste de vapor e m��todo do indofenol

Several extraction procedures are described for the determination of exchangeable and fixed ammonium, nitrate + nitrite, total exchangeable nitrogen and total nitrogen in certified reference soils and petroleum reservoir rock samples by steam distillation and indophenol method. After improvement of the original distillation system, an increase in worker safety, a reduction in time consumption, a decrease of 73% in blank value and an analysis without ammonia loss, which could possibly occur, were achieved. The precision (RSD < 8%, n = 3) and the detection limit (9 mg kg-1 NH4+-N) are better than those of published procedures.

Estimativa do fluxo de am��nia na interface ar-mar na Ba��a de Guanabara: estudo preliminar

In the begining of April 2004, concentrations of NHx (NH3 + NH4+) were measured in surface waters of the Guanabara Bay. Concentrations varied from 2 to 143 mmol L-1. Ammonia exchange at the air-sea interface was quantified using a numerical model. No measurement of NH3 concentration in air (c air) was performed. Thus, calculations of NH3 flux were based on the assumptions of c air = 1 and 5 ��g m-3. Fluxes were predominantly from the water to the atmosphere and varied from -20 to almost 3500 ��g N m-2 h-1.

Composi����o qu��mica da chuva e aporte atmosf��rico na Ilha Grande, RJ

Wet (n = 21) and dry (n = 23) deposition samples were collected from March to September 2002 at the southern coast of Ilha Grande. Rainwater pH varied from 4.3 to 6.3 and ionic concentrations (in ��mol L-1) decreased in the order Cl- > Na+ > Mg2+ > SO4(2-) > NO3- ~ NH4+ > K+ ~ H+ > Ca2+. Scavenging of sea-salt aerosols was the major source of Cl-, Na+, Mg2+, and Ca2+. Half of total SO4(2-) was non-sea-salt SO4(2-). Total deposition fluxes of NH4+, NO3-, and non-sea-salt SO4(2-) were respectively 9.3, 17.8, and 16.0 mol ha-1 month-1.

Efecto de la sustituci��n cati��nica y ani��nica en las transiciones de fase del LiNH4SO4

El �� L��NH4SO4 (�� LAS) presenta dos transiciones de fase, una alrededor de 10 ��C y la otra a 186 ��C. La fase intermedia es ferroel��ctrica. En este trabajo se estudia el efecto que produce la sustituci��n parcial del cati��n amonio por rubidio y del ani��n sulfato por seleniato en dichas transiciones de fase. Se establece la zona de existencia de las soluciones s��lidas Li(NH4)-^_^Rb^S04 y LiNH4(SO^)^_^(Se04)^ en las que se mantiene la estructura del �� LAS. La presencia de aniones seleniato o de cationes rubidio afecta a las transiciones de fase de alta y baja temperatura, por lo que, tanto los tetraedros sulfato como el cati��n amonio intervienen en dichas transiciones. Hay un efecto cooperativo entre el desorden de los grupos sulfato y las distorsiones de los tetraedros amonio. El mecanismo que puede explicar estas transiciones es del tipo orden-desorden.

Influ��ncia do pH sobre a estabilidade de suspens��es de alumina estabilizadas eletroestericamente

In this work, aqueous suspensions of aluminas with different particle sizes were evaluated. The effect of pH on the electrosteric stabilization using PMAA-NH4 (ammonium polymethacrylate) as deflocculant was studied. The amount of deflocculant was optimized and rheologic properties were determined at four different pH values. Sedimentation was also evaluated. For suspensions with pH 4, an electrostatic mechanism of stabilization was observed, probably due to a flat adsorption of PMMA- on the alumina surface, leading to a small efficiency in relation to steric stabilization. For a suspension with pH 12, the steric mechanism of stabilization prevails. Suspensions with pH 7 and 9 present a higher flocculation degree. In relation to particle size, A-1000 samples present a smaller particle size, leading to a smaller interparticle distance (IPS), making stabilization more difficult.