Investigation of process parameters in orthogonal cutting using finite element approaches.

The cutting force in orthogonal cutting of steel AISI 1045 was predicted by applying 2D finite element analysis (FEA) using two methods; (i) Lagrangian (LAG) and (ii) Arbitrary Lagrangian Eulerian (ALE). Johnson-Cook (J-C) models were used for defining plastic and failure properties of simulated materials. The predicted force was validated experimentally by using dynamometer. Comparison held between the simulation methods and experimental work in terms of results accuracy, reading stability, and chip morphology. Furthermore, this study adopted new modeling idea to control the excessive distortion of mesh elements along chip separation line by defining nearly zero damage criterion for these elements. The results demonstrated that LAG and ALE methods could predict the cutting force but with different accuracy, as LAG and ALE results deviated from experimental results with minimum error percentage 3.6% and 0.14% respectively. As well, ALE method showed stable force readings and continues smooth chip during simulation, while LAG method showed unstable force readings and discontinuous realistic chip.

Thermally enhanced TLD output: Impacts on the response curve.

Pre-irradiation background reading of thermoluminescent LiF dosimeters results in severe changes in the glow curve qualitatively and quantitatively. Current work focuses on the possible changes in the response of TLD-700 dosimeters after this effect. This work examines changes in the level of the glow curve as a whole and on the level of individual peaks as well. It was found that the response of TLD-700 dosimeters has increased by factors ranging from 20% to 44% in terms of area under the glow curve. Changes in individual peaks were examined by performing deconvolution for the glow curves. Results confirmed that the response due to such effect is not uniform over the studied temperature range and each individual peak has its own behavior either in terms of peak area or peak intensity. It was observed that the third peak (P3) leads these changes as the change in its area after being exposed to this thermally enhanced thermoluminescence output (TETO) effect was in the range from 4.1 to 3.0 folds compared to the corresponding values obtained without reading the background prior to irradiation. Peak intensity possesses similar behavior where peaks P2 and P4 are following to P3 in their response, the rest of peaks are either neutral or have negative response to TETO. Response curves of each deconvoluted peak in terms of peak area and maximum intensity are analyzed over the range (0.05-30) Gy and discussed in details.

Significance of the hepatitis C virus core antigen testing as an alternative marker for hepatitis diagnosis in Egyptian patients.

OBJECTIVE: Hepatitis C virus (HCV) core antigen (Ag) quantification by enzyme-immunoassays has been proposed as an economic and simpler alternative to HCV RNA detection. The current study was undertaken to assess the significance of HCV core antigen assay for the diagnosis of chronic HCV infection and monitoring response to antiviral therapy in Egyptian patients. PATIENTS AND METHODS: Sixty three HCV antibody positive patients and ten interferon-treated patients were included in the current study. The included patients were divided according to their viral load into four groups as follows; group I (n=10): HCV RNA loads ≤ 10000 IU/ml, group II (n=20): HCV RNA loads > 10000 ≤ 100000 IU/ml, group III (n=33): HCV RNA loads >100000 IU/ml and group IV (n=10): interferon-treated HCV patients with a negative HCV RNA.  Serum HCV core Ag and RNA loads were assayed and their correlations, including linear regression lines, were calculated. RESULTS: HCV core Ag exhibited a non-significant (p > 0.05) difference between all the studied groups. Concerning, group I patients, HCV core Ag levels and HCV RNA loads were positively correlated, with a correlation coefficient of 0.73 (p < 0.05). Group II and III showed stronger correlations; the recorded values were 0.81 (p < 0.0001) and 0.94 (p < 0.0001) for group II and III, respectively. CONCLUSIONS: HCV core Ag test can be used as an alternative to HCV RNA tests to evaluate chronic infection when the HCV RNA test is unavailable, but is not reliable enough for treatment monitoring.

Radiological hazards of TENORM in the wasted petroleum pipes.

Disposal petroleum pipes containing sludge and scale as a technically enhanced natural occurring radioactive material (TENORM) leads to internal and external radiation hazards and then a significant radiation dose to the workers. In order to contribute to a future waste management policy related to the presence of TENORM in the disposal sites of wasted petroleum pipes, scale and sludge as TENORM wastes are collected form these disposal pipes for radiometric analysis. These pipes are imported from onshore oilfields at south Sinai governorate, Egypt. The highest mean (226)Ra and (228)Ra concentrations of 519 and 50 kBq/kg respectively, were measured in scale samples. Sludge lies within the normal range of radium concentration. The average absorbed dose caused by the exposure to the wasted pipes equal to 4.09 microGy h(-1) from sludge and 262 microGy h(-1) from scale. This is much higher than the acceptable level of 0.059 microGy h(-1). Due to radon inhalation, important radon related parameters are calculated which advantage in internal dose calculation. Fairly good correlation between real radium content and radon exhalation rate for sludge samples is obtained. The hazards from sludge come from its high emanation power for radon which equal to 3.83%. The obtained results demonstrate the need of screening oil residues for their radionuclide content in order to decide about their final disposal.

Radon effective dose from TENORM waste associated with petroleum industries.

Technically enhanced naturally occurring radioactive material (TENORM) associated with petroleum industries can be accumulated with elevated quantities and therefore can threat the workers through external and internal exposure. Measurements of radon-related parameters give information about the radioactivity levels in the TENORM waste using the well-established correlation. Also, it is useful to calculate the internal exposure due to radon inhalation in terms of effective radon dose. Among radon-related parameters, areal exhalation rate is the most suitable for characterising land and objects with only upper surface contamination in the case of petroleum waste. The TENORM in this study is collected from waste storage areas located near oilfields at south Sinai governorate, Egypt. The average values of exhalation rates as measured by Lucas cell based on delay count method are 273 +/- 144 and 38 +/- 8 Bq m(-2) h(-1) for scale and sludge, respectively. Whereas, two count method gives results with 18 and 20 % lower values for scale and sludge, respectively with good correlation coefficient of 0.999 and 0.852, respectively. Sealed cup fitted with CR-39 gives results compatible with Lucas cell with minor deviation in case of scale due to its thoron content. The results of CR-39 are qualified by taking into consideration the correction for back diffusion effect. The effective radon dose was calculated for different simulated radioactive waste storage areas with different contaminated areas and air ventilation rate. Minimising the contaminated areas and building up efficient ventilation systems can reduce the internal exposure even in the case of RWSA-containing TENORM with elevated radioactivity.

Transanal one-stage endorectal pull-through for Hirschsprung's disease: a multicenter study.

BACKGROUND/PURPOSE: Transanal endorectal pull-through (TEPT) is the latest development in treatment of Hirschsprung's disease (HD). This prospective study was designed to evaluate the safety and efficacy of 1 stage TEPT technique in the management of patients with HD. METHODS: One hundred forty-nine children (116 boys and 33 girls) aged 8 days to 14 years underwent 1 stage TEPT procedure over an 18-month period at 5 Egyptian academic pediatric surgical centers and affiliated hospitals. Median follow-up was 12 months (range, 3 to 21 months). These patients were evaluated with regard to age, sex, length of the aganglionic segment, intraoperative details, and postoperative functional results or complications. An electromyogram (EMG), endorectal ultrasound scan, and lower gastrointestinal (GI) motility studies were reserved for patients with postoperative problems with bowel control. RESULTS: Mean operating time was 120.2 +/- 27.8 minutes (range, 60 to 210 minutes). The average length of resected bowel was 26.8 +/- 12.4 cm (range, 15 to 45 cm). Thirteen patients required laparotomy because of extension of aganglionic segment beyond the sigmoid colon in 9, tear in the mesenteric vessels in 2, and difficulties in getting to the submucosal plane in 2. Three deaths (2%) occurred 3 days, 4 days, and 4 weeks postoperatively, respectively. Postoperative complications included transient perianal excoriation in 48 patients (30 were <3 months of age), enterocolitis (n = 26), anastomotic stricture (n = 7), recurrent constipation (n = 6), hypoganglionosis at distal end of pulled through segment (n = 2), cuff abscess (n = 3), anastomotic leak (n = 1), adhesive bowel obstruction (n = 1), and rectal prolapse (n = 1). Complete anorectal continence was noted in 35 of 42 (83.3%) children older than 3 years, whereas soiling and frequent accidents still occur in 7, who showed a steady improvement in their continence status. CONCLUSIONS: One-stage TEPT technique is both feasible and safe technique in properly selected children with rectosigmoid HD in all ages. The technique is easily learned and is associated with excellent clinical results.

Total urogenital sinus mobilization in the repair of cloacal anomalies and congenital adrenal hyperplasia.

PURPOSE: Urogenital sinus mobilization has facilitated markedly the vaginal reconstruction in cases of cloacal anomalies. Application of the same technique in cases of congenital adrenal hyperplasia has resulted in cosmetic and functional improvement. METHODS: Total urogenital sinus mobilization was used as a part of the repair in 9 patients: 6 with congenital adrenal hyperplasia (4 high and 2 mid vaginal confluence), and 3 with cloacal anomalies; sinus mobilization to the level of the symphesis pubis allowed the vagina to reach the perineum in all cases. Their age ranged from 6 to 8 months, and follow-up ranged from 6 months to 2 years. In the former group, the mobilized sinus was split dorsally and used as an anterior vaginal flap. Cases of cloaca needed weekly dilatation early postoperatively. RESULTS: All patients are below 3 years of age, so urinary control assessment is not yet objective; however, all mothers reported dry intervals. Examination 6 months postoperatively showed wide vagina and excellent cosmetic appearance in all cases. CONCLUSIONS: Total urogenital mobilization provides an easier way for vaginal reconstruction. The improved cosmetic appearance and the absence of vaginal stenosis provided by this technique is a major advantage in the management of these difficult surgical situations.

Idiopathic intussusception: the role of laparoscopy.

BACKGROUND: The use of a barium enema affords both diagnostic confirmation and a chance for nonsurgical complete reduction of the intussusception, which must be proven by adequate reflux of barium into the distal ileum. If this does not occur, it is assumed that the intussusception has not been reduced, and the infant is taken straight to the operating room for laparotomy and surgical treatment. The aim of this study is to limit unnecessary surgical explorations by the diagnostic and the therapeutic policy of laparoscopy with assisted hydrostatic saline reduction under general anesthesia. METHODS: Over a period of 3 years, 90 patients with intussusception were treated. Twenty patients in whom hydrostatic reduction was contraindicated were treated initially by surgery. In the remaining 70 patients, hydrostatic reduction was successful in 50 (71%), and laparoscopy was performed in 20 patients before laparotomy. Hydrostatic saline reduction was used when there was failure of reduction seen by laparoscopy. RESULTS: In 20 patients, laparoscopy showed reduction of intussusception in eight patients (40%), and saline hydrostatic reduction was successful in six patients (30%), with failure of reduction in six patients (30%) necessitating laparotomy. CONCLUSION: The use of laparoscopy for diagnosis of failure of reduction of intussusception and the hydrostatic reduction by saline enema during laparoscopy saved 14 patients from unnecessary laparotomy.

Laparoscopic classification and treatment of the impalpable testis.

Laparoscopic orchiopexy has gained popularity in recent years. However, the decision when to perform one-stage laparoscopic orchiopexy without division of the spermatic vessels versus initial ligation of the spermatic vessels followed later by orchiopexy is not clear. A new laparoscopic classification to facilitate decision-making during laparoscopy, according to the position of the impalpable testis and the relation of the spermatic vessels and vas deferens to the internal ring, with a management protocol based on this classification is presented. Over a 2-year period, a total of 37 boys with 52 impalpable gonads underwent a laparoscopic procedure. Four laparoscopic types of testis were noted: type I: no testis visualized; type II: a testis seen at the internal ring with the vas and vessels looping to the internal ring; type III: testis at the internal ring, with vas and vessels going to the testis directly; and type IV: intra-abdominal testis not related to the internal ring. Of the 52 gonads, 19 (36.5%) were type I, 13 (25%) type II, 6 (11.5%) type III, and 14 (27%) type IV. Thirty-three testes were followed up (mean follow-up 8 months); 3 showed atrophy (11%) and 4 were retracted at the scrotal neck after staged, laparoscopic-assisted orchiopexy (LAO). Laparoscopy is of great value for both diagnosis and management of impalpable testes. A classification based on laparoscopic findings will help in planning further surgical action, and LAO is a safe and effective form of operative management for impalpable testes.

Folic acid binding by human plasma albumin.

Binding of [3H]folate to pure human plasma albumin was studied by Sephadex G-200 gel filtration in a steady-state system. The experiments showed the presence of two binding sites per molecule of albumin and an equilibrium constant of 0.9x10(3) 1/mol. With normal human plasma, only albumin bound exogenous [3H]folate with nearly the same equilibrium constant. In human blood plasma at concentrations of less than 10(-5) mol/1, 50% of folate was free, and 50% was bound to albumin. Binding was maximal at about pH 6 and negligible above pH 8 and below pH 4.5. Neither human transferrin nor Cohn fraction II was able to bind [3H]folate.