Study on the dopant concentration ratio in thulium-holmium doped silica fibers for lasing at 2.1µm.

We present the fabrication and laser performance of thulium-holmium co-doped silica fibers when cladding pumped at ∼790 nm. By using the hybrid gas phase-solution doping process in conjunction with the MCVD preform fabrication technique, the doping concentration and the Tm:Ho ratio were varied to study the energy transfer efficiency from Tm3+ to Ho3+. Our study indicates that for a thulium concentration that has resulted in an efficient two-for-one cross- relaxation process with 790 nm pumping, and while maintaining a Tm:Ho concentration ratio in the range ∼ 10 to 20, the energy transfer efficiency has reached above 75%. In a free-running laser cavity, the pump power limited laser output of 38W with a slope efficiency of 56% at 2.1 microns is demonstrated.

Highly efficient thulium-doped high-power laser fibers fabricated by MCVD.

We report a hybrid process by combining both vapor-phase and solution-doping techniques of rare-earth doped preform fabrication in conjunction with the MCVD technique, in order to fabricate highly efficient Tm-doped laser fibers. The proposed fabrication route takes advantage of co-doping silica with high alumina content through the vapor-phase doping process, which is otherwise difficult to achieve using conventional solution doping technique. In addition, by employing the solution doping method, high-purity thulium halide precursors that have low vapor pressures up to several hundred degree Celsius. These high-purity thulium halide precursors can be used to dope the fiber core region with a high thulium concentration that is optimized for an efficient two-for-one cross-relaxation process for 79xnm diode pumped thulium-doped fiber laser. Fibers fabricated using the hybrid approach show more homogeneous and flat-top dopant profiles, compared with the conventional approach, where both aluminum and thulium are incorporated in the core through solution doping. This will ensure that more doped region will take part in the cross-relaxation process. Superior laser performance with a slope efficiency of >70% in the two-micron band has been demonstrated when diode pumped at ~790nm.

Deshidratación hiponatrémica-hipoclorémica de repetición: inicio clínico de fibrosis quística en un lactante con genotipo R334W/1812(-1)G->A / Recurrent episodes of hyponatremic-hypochloremic dehydration as a presentation of cystic fibrosis in an infant with R334W/1812(-1)G->A mutation

La fibrosis quística (FQ) es una enfermedad exocrina autosómica recesiva de afectación multisistémica. El defecto asociado a la FQ se encuentra en un regulador transmembrana que actúa principalmente como canal de cloro. Los pacientes suelen presentar clínica respiratoria o digestiva. La severidad de la enfermedades multifactorial, y uno de sus determinantes es el nivel de actividad de la proteína CTFR y el tipo de mutación del paciente. El paciente de este caso desarrolló episodios recurrentes de anorexia, pérdida de peso, deshidratación y anomalías hidroelectrolíticas. A pesar de estas manifestaciones poco descritas en la bibliografía, se llegó al diagnóstico de FQ. Se encontraron las mutaciones R334W y 1812-1G-4. La FQ se debe considerar particularmente en los lactantes que presentan la clínica descrita de deshidrataciones recurrentes con alcalosis metabólica, hiponatremia e hipocloremia inexplicada por otras causas, incluso en ausencia de síntomas respiratorios, digestivos o fallo de medro(AU)

Cystic fibrosis (CF) is an autosomal recessive exocrine disease affecting multiple organ systems. The defect associated with CF is in the cystic fibrosis transmembrane regulator (CFTR), which acts primarily as a chloride channel. Patients with CF usually present with respiratory and/or gastrointestinal abnormalities. The severity of the disease is multifactorial, one of the factors depends on the level of activity of the CFTR protein, which is related with the mutation type that affects the patient. An infant is presented who developed recurrent episodes of anorexia, weight loss, dehydration and electrolyte abnormalities. CF was diagnosed showing an unusual and not very publicized presentation of the disease. Mutations R334W and 1812-1G-A were found. CF should be considered in patients of any age, but particularly in infants, presenting with recurrent episodes of hyponatremic hypochloremic dehydration with metabolic alkalosis unexplained by other causes, even in the absence of respiratory or gastrointestinal symptoms or failure to thrive(AU)

Nefronía lobar aguda: a propósito de tres casos / Acute lobar nephronia: a report of three cases

La nefronía lobar aguda (NLA) es una infección bacteriana localizada en el parénquima renal, escasamente descrita en la literatura pediátrica. Presentamos tres casos de NLA, uno de ellos adquirido por vía hematógena. En los tres casos el diagnóstico se realizó mediante ecografía renal. Queremos resaltar la utilidad de la ecografía renal para el diagnóstico precoz, así como la importancia de un adecuado tratamiento antibiótico(AU)

Acute lobar nephronia (ALN) is an acute bacterial infection localized in the renal parenchyma, seldom described in paediatric literature. We present three cases of ALN, one of the macquired through the blood stream. In all three cases, the diagnosis was made by renal ultrasonography. We highlight the utility of renal ultrasonography for early diagnosis and the importance of appropriate antibiotic treatment(AU)