Modeling and experimental evaluation of membrane distillation aimed at urine treatment for direct potable reuse in space stations

Improving wastewater reuse systems represents a game changer for the economy of space exploration activities. The goal of this research is to evaluate direct contact membrane distillation for the treatment of urine aimed at direct potable reuse in space stations. A transient, 2-D model able to predict the membrane distillation system behavior under different operating conditions is developed. The model is validated by experimental tests conducted with a synthetic urine-like feed solution, considering both productivity and final water quality. The water flux and quality analyses imply high rejection of soluble salts and organics. However, direct water reuse may be compromised by the ammonia passage. A sensitivity analysis is thus performed to investigate the effects of feed pH, temperature, and cross-flow velocity on water flux and ammonia passage. The system shows the capability of treating 8 L of urine up to 90–95 % recovery rate, during 10 h of daily operation at 40 °C feed and 20 °C distillate inlet temperatures. This amount is sufficient to satisfy four crew members while meeting high system compactness. Concurrently, the ammonia passage may be limited by lowering the feed pH, thus easing the post-treatment steps necessary for safe direct reuse

MANEJO FLORESTAL EMPRESARIAL NO ACRE: CUSTOS DA ATIVIDADE PRÉ-EXPLORATÓRIA NA FLORESTA ESTADUAL DO ANTIMARY.

Esta pesquisa aborda a atividade madeireira sob o regime de concessão florestal desenvolvido no Estado do Acre. Os objetivos do presente estudo são: identificar o custo da produção do manejo florestal sustentável (MFS) para produção madeireira, tendo como base a Floresta Estadual do Antimary (FEA); e, quantificar o valor, a ser pago pela terra, numa área destinada como floresta pública de produção, no ano de 2005. Para tal, foi considerada, como premissa básica, um ciclo de corte de 15 anos. As técnicas usadas identificaram o custo de produção da madeira com origem em uma florestal manejada (Cmf), o valor presente líquido (VPL) do MFS e o valor esperado da terra (VET), os quais foram calculados considerando as taxas de desconto de 4%, 6%, 8%, 10% e 12% ao ano. Os principais resultados obtidos foram: a uma taxa de desconto de 4% ao ano, uma empresa gastaria, com o manejo florestal, US$68,50/ha e geraria um VPL de US$ 92,18/ha. Por outro lado, a 12% ao ano, estes valores decresceriam para US$62,53/ha e US$ 81,34/ha, respectivamente. O preço máximo que poderia ser pago por um hectare de terra na FEA, em 2005, para que o MFS fosse remunerado numa taxa de 4% a.a., foi de US$218,17/ha, visto que, a partir de 6$ 199,03/ha).---------------------------------------------This research addresses the timber activity under a forest concession system in the State of Acre. Its objectives are: to identify the production cost related to sustainable forest management (SFM) for timber yield, having as scenario the Antimary State Forest (ASF); and, quantify the value to be paid for the land, in an area designed as public production forest, in the year 2005. So, it was recognized as basic foundation, a 15-year cutting cycle. The techniques used identified the production cost of log coming from a managed forest area (Cmf), the net present value (NPV) concerning SFM and the land expectation value (LEV), which were calculated adopting annual interest rates of 4%, 6%, 8%, 10% and 12%. The main results obtained were: at annual interest rate of 4%, a firm would spend, with forest management US$68,50/ha and would generate US$ 92,18/ha as NPV. On the another hand, at 12% a.a., these value would decrease to US$62,53/ha and US$ 81,34/ha, respectively. The maximum price which could be paid for one hectare of land in the ASF, in 2005, in order to remunerate SFM at 4% a.a., was US$218,17/ha, because adopting interest rates greater than 6$ 199,03/ha).Manejo florestal sustentável, Custo da produção madeireira, Economia florestal, Valor esperado da terra, Sustainable forest management, timber production cost, Forest economics, Land expectation value, Resource /Energy Economics and Policy,

Minimizing the risk of graft failure after anterior cruciate ligament reconstruction in athletes. A narrative review of the current evidence

Anterior cruciate ligament (ACL) tear is one of the most common sport-related injuries and the request for ACL reconstructions is increasing nowadays. Unfortunately, ACL graft failures are reported in up to 34.2% in athletes, representing a traumatic and career-threatening event. It can be convenient to understand the various risk factors for ACL failure, in order to properly inform the patients about the expected outcomes and to minimize the chance of poor results. In literature, a multitude of studies have been performed on the failure risks after ACL reconstruction, but the huge amount of data may generate much confusion. The aim of this review is to resume the data collected from literature on the risk of graft failure after ACL reconstruction in athletes, focusing on the following three key points: individuate the predisposing factors to ACL reconstruction failure, analyze surgical aspects which may have significant impact on outcomes, highlight the current criteria regarding safe return to sport after ACL reconstruction

Book review : Lectures on the Riemann Zeta Function, by Henryk Iwaniec

International audienceLectures on the Riemann Zeta Function, by Henryk Iwaniec, University Lecture Series, Volume: 62, American Mathematical Society, Providence, RI, 2014, viii+119 pp., Softcover, ISBN 978-1-4704-1851

Goldbach numbers represented by polynomials

Let N be a large positive real number. It is well known that almost all even integers in the interval [N, 2N] are Goldbach numbers, i.e. a sum of two primes. The same result also holds for short intervals of the form [N, N+H], see Mikawa [4], Perelli-Pintz [7] and Kaczorowski-Perelli-Pintz [3] for the choice of admissible values of H and the size of the exceptional set in several problems in this direction. One may ask if similar results hold for thinner sequences of integers in [N, 2N], of cardinality smaller than the upper bound for the exceptional set in the above problems. In this paper we deal with the polynomial case

Book review : Lectures on the Riemann Zeta Function, by Henryk Iwaniec

Lectures on the Riemann Zeta Function, by Henryk Iwaniec, University Lecture Series, Volume: 62, American Mathematical Society, Providence, RI, 2014, viii+119 pp., Softcover, ISBN 978-1-4704-1851