Estudio y desarrollo de un secadero de adobes de ladrillos macizos

Se presenta el estudio y desarrollo de un secadero de adobes de una fábrica de ladrillosmacizos de la zona de Makalle (Chaco). Se obtuvieron curvas representativas del proceso de secado para una capacidad de 5000 adobes en el interior del secadero. Se logró determinar para una temperatura aproximada de 50ºC del aire que ingresa al secadero, la cantidad de agua extraída de los adobes es de 6265 kg y el tiempo final del proceso de secado es de aproximadamente 60 horas. Además se seleccionaron los diferentes componentes del secadero como ser: ventiladores, economizador y bomba de calor.

Urinary tract infection in men

Uri nary tract in fec tion in men Ab stract. Ob jec tive: To ex plore the prev alence and mi cro bi ol ogy of uri nary tract in fection (UTI) in symp tom atic men in a pri mary care set ting and to de ter mine the ap pro pri ateness of pa tient man age ment of these con ditions by the gen eral prac ti tio ners. Meth ods: A cross-sec tional sur vey was car ried out matching doc u men ta tion of symp toms and man agement with urine cul ture and re sults of sus cep tibil ity tests. All pa tients pre sent ing with symptoms typ i cal for a UTI in 36 teach ing gen eral prac tices in the area of Göttingen, Ger many, were el i gi ble for en rol ment in the study. 15% (n = 90) of all pa tients were adult men. Gen eral prac ti tio ners (GPs) were in structed to man age pa tients as usual. Pa tient char ac ter is tics, dipstick tests and treat ment were matched with results of urine cul tures and sus cep ti bil ity testing. Re sults: Men pre sent ing with symp toms in dic a tive of UTI were pre dom i nantly el derly (me dian age 61 years) and 41% had ad di tional risk fac tors. An ti bi ot ics were pre scribed for 36%, but these were not well-tar geted. Urine cul ture re vealed UTI in 60%, of which half had low col ony counts (23% of all pa tients) or multi ple bac te rial growth (7%); 40% had ster ile urine. Dip stick tests proved un help ful: leu kocytes and ni trite had sen si tiv i ties of 54% and 38%, specificities of 55% and 84%, pos i tive pre dic tive val ues of 65% and 78% and neg ative pre dic tive val ues of 44% and 46%, re spectively. Re sis tance lev els were 53% for amoxicillin and cefaclor, 28% for cefixim, 22% for ciprofloxacin, 34% for both trimethoprim as in di vid ual sub stance and the com bi na tion with sulfamethoxazole (cotrimoxazole) and 25% for ni tro fu ran toin. Con clusion: Men with symp toms in dic a tive of a UTI should not be treated em pir i cally. A urine culture and antibiogram should be ob tained before a treat ment de ci sion is made. A low-count UTI was com mon and should not be con sidered nor mal

Microscopic dynamics in liquid metals: the experimental point of view

The experimental results relevant for the understanding of the microscopic dynamics in liquid metals are reviewed, with special regards to the ones achieved in the last two decades. Inelastic Neutron Scattering played a major role since the development of neutron facilities in the sixties. The last ten years, however, saw the development of third generation radiation sources, which opened the possibility of performing Inelastic Scattering with X rays, thus disclosing previously unaccessible energy-momentum regions. The purely coherent response of X rays, moreover, combined with the mixed coherent/incoherent response typical of neutron scattering, provides enormous potentialities to disentangle aspects related to the collectivity of motion from the single particle dynamics. If the last twenty years saw major experimental developments, on the theoretical side fresh ideas came up to the side of the most traditional and established theories. Beside the raw experimental results, therefore, we review models and theoretical approaches for the description of microscopic dynamics over different length-scales, from the hydrodynamic region down to the single particle regime, walking the perilous and sometimes uncharted path of the generalized hydrodynamics extension. Approaches peculiar of conductive systems, based on the ionic plasma theory, are also considered, as well as kinetic and mode coupling theory applied to hard sphere systems, which turn out to mimic with remarkable detail the atomic dynamics of liquid metals. Finally, cutting edges issues and open problems, such as the ultimate origin of the anomalous acoustic dispersion or the relevance of transport properties of a conductive systems in ruling the ionic dynamic structure factor are discussed.Comment: 53 pages, 41 figures, to appear in "The Review of Modern Physics". Tentatively scheduled for July issu

Dislocation Loop Formation and Growth under In Situ Laser and/or Electron Irradiation

Vacancies and interstitial atoms are primary lattice (point) defects that cause observable microstructural changes, such as the formation of dislocation loops and voids in crystalline solids. These defects' diffusion properties determine the phase stability and environmental resistibility of macroscopic materials under ambient conditions. Although in situ methods have been proposed for measuring the diffusion energy of point defects, direct measurement has been limited. In this study, we propose an alternative in situ method to measure the activation energy for vacancy migration under laser irradiation using a pulsed laser beam from a laser-equipped high-voltage electron microscope (laser-HVEM). We made in situ observations that revealed the formation and growth of vacancy dislocation loops in an austenitic stainless steel during laser irradiation. These loops continued to grow when thermal annealing was performed after laser irradiation at the same temperature. We anticipate that laser-HVEM will provide a new method for investigating lattice defects