Modeling ventilation time in forage tower silos

The fermentation process in forage tower silos produces a significant amount of gases, which can easily reach dangerous concentrations and constitute a hazard for silo operators. To maintain a non-toxic environment, silo ventilation is applied. Literature reviews show that the fermentation gases reach high concentrations in the headspace of a silo and flow down the silo from the chute door to the feed room. In this article, a detailed parametric analysis of forced ventilation scenarios built via numerical simulation was performed. The methodology is based on the solution of the Navier-Stokes equations, coupled with transport equations for the gas concentrations. Validation was achieved by comparing the numerical results with experimental data obtained from a scale model silo using the tracer gas testing method for O2 and CO2 concentrations. Good agreement was found between the experimental and numerical results. The set of numerical simulations made it possible to establish a simple analytical model to predict the minimum time required to ventilate a silo to make it safe to enter. This ventilation time takes into account the headspace above the forage, the airflow rate, and the initial concentrations of O2 and CO2. The final analytical model was validated with available results from the literature.

Impact of two particle measurement techniques on the determination of N95 class respirator filtration performance against ultrafine particles

The purpose of this experimental study was to compare two different particle measurement devices; an Electrical Low Pressure Impactor (ELPI) and a Scanning Mobility Particle Sizer (SMPS), to measure the number concentration and the size distribution of NaCl salt aerosols to determine the collection efficiency of filtering respirators against poly disperse aerosols. Tests were performed on NIOSH approved N95 filtering face-piece respirators (FFR), sealed on a manikin head. Ultrafine particles found in the aerosols were also collected and observed by transmission electron microscopy (TEM). According to the results, there is a systematic difference for the particle size distribution measured by the SMPS and the ELPI. It is largely attributed to the difference in the measurement techniques. However, in spite of these discrepancies, reasonably similar trends were found for the number concentration with both measuring instruments. The particle penetration, calculated based on mobility and aerodynamic diameters, never exceeded 5% for any size range measured at constant flow rate of 85 L/min. Also, the most penetrating particle size (MPPS), with the lowest filtration efficiency, would occur at a similar ultrafine size range <100 nm. With the ELPI, the MPPS was at 70 nm aerodynamic diameter, whereas it occurred at 40 nm mobility diameter with the SMPS.

Amputation du gland après circoncision

Introduction

Sous nos climats, la circoncision reste l’intervention la plus couramment pratiquée chez le garçon. Elle est souvent réalisée par un personnel paramédical non qualifié, ou même en dehors du milieu médical dont les notions de chirurgie et d’asepsie sont aléatoires. Elle est réputée comme chirurgie bénigne, mais des complications majeures parfois très graves, engageant le pronostic sexuel, voire vital, peuvent survenir. Le but de ce travail était de rapporter les amputations du gland secondaires à la circoncision et reçues en milieu hospitalier urologique.

Patients et méthode

Nous rapportons huit cas d’amputation du gland suite à une circoncision en milieu extrahospitalier selon les méthodes traditionnelles.

Résultats

L’âge moyen des enfants est de six ans (trois à huit ans). L’amputation du gland était faite lors de la circoncision dans quatre cas, dont deux avec section complète. Dans les autres cas, il s’agissait d’une nécrose du gland à cause d’un arc électrique lors de l’utilisation inadéquate du bistouri électrique. Une reconstruction urgente du gland n’avait pu être réalisable que dans trois cas. Le gland sectionné dans le quatrième cas était de mauvaise qualité. On n’a noté qu’un seul succès de revascularisation du gland. Le délai de consultation en cas de nécrose du gland était de trois jours en moyenne. Le traitement n’avait consisté qu’en la réalisation d’une méatoplastie pour obtenir un méat urétral satisfaisant avec réfection de la peau pénienne.

Conclusion

La section du gland demeure une complication, certes rare de la circoncision mais très grave, engageant le pronostic sexuel ultérieur de l’enfant. Cela rend cette intervention non anodine et doit inciter à ne la réaliser qu’en milieu spécialisé par un personnel compétent.

Screening of ΔF508 mutation and IVS8-poly T polymorphism in CFTR gene in Tunisian infertile men without CBAVD

It is well established that cystic fibrosis transmembrane conductance regulator gene (CFTR) mutations are involved in congenital bilateral absence of the vas deferens (CBAVD), causing obstructive azoospermia and male infertility. Also, several studies reported a relatively high prevalence of CFTR gene mutations in healthy men presenting reduced sperm quality. In this study, we investigate ΔF508 mutation and IVS8-polyT polymorphism in CFTR gene in Tunisian infertile men without CBAVD. Genetic analyses were performed in 148 infertile patients and 126 fertile individuals. The polymorphic IVS8-polyT tract in CFTR gene was analysed in only 129 infertile patients and 54 individuals of control group. As well, we screened for Y chromosome microdeletions in all infertile patients. No ΔF508 mutation was diagnosed either in infertile patients or in control group. 5T allele of IVS8-polyT tract was found in both infertile men (4.26%) and fertile individuals (8.33%). 5T/5T genotype was observed only in two azoospermic patients without Y microdeletions. The most frequent genotype of IVS8-polyT tract in infertile men and controls was 7T/7T (69.75% and 59.25% respectively). There was no association between IVS8-polyT polymorphism and reduced semen quality. Neither ΔF508 mutation nor 5T allele is involved in pathogenesis of male infertility in Tunisian infertile patients without CBAVD.

Genotyping of Tunisian azoospermic men with Sertoli cell-only and maturation arrest

Azoospermia factor (AZF) deletions were associated with severe oligospermia and azoospermia with testicular histologies varying from maturation arrest (MA) to Sertoli cell-only (SCO) phenotypes. Abnormal androgen receptor (AR) structure or function has also been implicated in male infertility. To assess the contribution of these genetic defects to azoospermic patients, 19 Tunisian men with SCO (n = 13) or MA (n = 6) were enrolled in this study. Using immunohistochemistry method, we evaluated the expression of AR in testicular biopsy for the two phenotypes. PCR with primers flanking the AR-(CAG)n region and direct sequencing were used to determine AR-(CAG)n length. And PCR amplification of 14 sequence-tagged sites (STSs) located at Yq was used to determine the rate and extent of Y microdeletions. We found a significant difference of the AR expression between SCO and MA cases. Hence, this expression in the testis depends on the status of spermatogenesis. However, we did not find any relationship between the (CAG) repeat and the testicular histology (neither for SCO nor MA). On the other hand, we found a high frequency of AZF deletions (46.2%) in SCOS and in MA (50%). The present results also suggest the contribution of Y chromosome microdeletions in SCO and MA pathogenesis.

Evolution of impaired renal function after external continent urinary diversion (Mitrofanoff principle)

OBJECTIVE

To study the evolution of impaired renal function after external continent urinary diversion (Mitrofanoff principle) (ECUD-M) associated with ileocystoplasty.

PATIENTS AND METHODS

Over 18 years from 1992 to 2009, ECUD-M with ileocystoplasty was performed in 120 patients with mean age of 25.5 years. Renal impairment was evident in 43 patients (17 children and 26 adults).

RESULTS

Ninety percent of patients demonstrated a neurologic bladder and mild to moderate renal failure. Initially, all patients underwent continuous bladder drainage for a mean of 3 weeks. Renal function improved in 35 patients, although with persistent mild renal insufficiency. The other patients demonstrated moderate persistent residual renal insufficiency. During a mean follow-up of 10 years (range, 1-18 years), renal function returned to normal in 13 patients, stabilized at lower values in 15, and remained moderate in 5. After a mean follow-up of 8 years (range, 6-12 years), renal failure gradually worsened, increasing to higher values in 6 patients and leading to hemodialysis in 4. One patient underwent living-donor kidney transplantation, with good evolution.

CONCLUSION

ECUD-M with ileocystoplasty can lead to normalization unless stabilizationof impaired residual renal function by eliminating the obstructive factor provides self-adequate management of the diversion. The procedure delays for the need forhemodialysis therapy, and enables patients to prepare for kidney transplantation into a previously reconstructed lower urinary tract.

Analysis of azoospermia factor loci polymorphisms among Tunisian infertile men with varicocele

AIMS

The preponderance of experimental data from clinical and animal models demonstrates an adverse effect of varicocele on spermatogenesis. The review of the literature shows that there may be an underlying genetic etiology in varicocele. Here, we explore the Yq microdeletions among infertile men to evaluate their involvement in varicocele development and sperm production defect.

RESULTS

Microdeletions of 14 sequence-tagged-sites in the Yq11 region were screened in 210 infertile men using polymerase chain reaction techniques. Out of 210 infertile men, 69 (33%) men were with varicocele. Our results showed that the risk to develop varicocele is increased among infertile men with spermatogenesis (oligo-normospermia) (odds ratio = 3.57, confidence interval 95%: 1.49-8.84). However, we did not find any relationship between Y chromosome microdeletions and varicocele appearance (p = 0.73). In addition, a significant association was found between Y microdeletions and oligospermia (p < 10(-8)) or azoospermia (p < 10(-8)) using patients with normospermic characteristics as a control.

CONCLUSION

Our work showed the absence of relationship between Y chromosome microdeletions and varicocele development and the association of the two factors, independently, with sperm production defect.

Persistent Müllerian duct syndrome with torsion of a transverse testicular ectopia: first reported case

Persistent Müllerian duct syndrome with transverse testicular ectopia is a rare pathologic association. A 7-month-old boy was admitted to the emergency department with a right testicular swelling. Physical examination revealed a tender right testis, the upper limits of which could not be palpated. The left testis was impalpable. An ultrasound revealed a normal right testis with an evident blood flow, overcome by a similar mass but avascular. At surgery, the right hernial sac contained both testes with an infantile uterus and fallopian tubes. The left testis was viable after manipulation. Proximal-salpingectomy with corporeal hysterectomy was performed to allow bilateral scrotal orchiopexy.

Childhood nephrectomy indications: a changing profile

AIM

To assess the changing profile of children's nephrectomy indications in the south of Tunisia during the last two decades.

METHODS

There were 94 children who underwent nephrectomy between 1982 and 2007. They were classified into two groups. The first group included 55 out of 511 hospitalized children between 1982 and 1994, the second included 39 out of 382 hospitalized children between 1995 and 2007. K2 (Chi-squared) test was used for this statistical analysis. A P value of < 0.05 was considered statistically significant.

RESULTS

The average was 7. Pathologies leading to nephrectomies were dominated in both groups by 3 main aetiologies: urolithiasis (42.5%), Wilm's tumors (21.3%) and pelvi-ureteric junction (13.8%). While in the first group, urolithiasis was found to be the major indication of nephrectomy (54.5%, p<0.05), in the second group, kidney tumors had become the major indication (33%, p<0.05) followed by urolithiasis (25.6%). So, the rate of nephrectomies performed due to urolithiasis had clearly decrease (P = 0.005), but there were no statistical differences observed between the rates of nephrectomies performed due to tumors or upper urinary tract malformations in the two groups.

CONCLUSION

The profile of children's nephrectomy indications in Tunisia stretches currently to be similar to the one of the industrialized countries, with regression of evolved kidney lithiasis leaving place to the tumorous pathologies, because of early detection, improvement and appropriate treatment of urinary lithiasis.

Performance of mechanical filters and respirators for capturing nanoparticles--limitations and future direction

There is an increasing concern about the health hazard posed to workers exposed to inhalation of nanoparticles. Inhaling nanoparticles possess an occupational hazard due to elevated amount emitted to the atmosphere and working environment. Nanoparticles have potential toxic properties: the high particle surface area, number concentration, and surface reactivity. Inhalation, the most common route of nanoparticle exposure, has been shown to cause adverse effects on pulmonary functions and the deposited particles in the lung can be translocated to the blood system by passing through the pulmonary protection barriers. Filtration is the simplest and most common method of aerosol control. It is widely used in mechanical ventilation and respiratory protection. However, concerns have been raised regarding the effectiveness of the filters for capturing nanoparticles. This paper reviews the literature on the filtration performance of mechanical filters and respirators against nanoparticles. It includes the discussion about filtration mechanisms, theoretical models, affecting factors of the filtration efficiency, and testing protocols for respirator and filter certification.