Carboxylation of polypropylene by reactive extrusion with functionalized peroxides for use as a compatibilizer in polypropylene/polyamide-6,6 blends

Variable quantities of functionalized peroxides bearing carboxylic acid groups were reacted with polypropylene (PP) in a twin-screw extruder. Systematic variations in the molecular structure of the peroxides were found to significantly affect the grafting efficiency of the carboxylic acid group onto the PP backbone, as well as affect the polymer degradation process. This behavior was attributed to the relative reactivities of the different free radicals generated by thermal decomposition of the peroxides. Furthermore, the functionalized polypropylene (f-PP) was investigated as a compatibilizing additive for 80/20 PP/PA-6,6 (polyamide 6,6) blends. With incorporation of the f-PP into the blends, differential scanning calorimetry (DSC) showed an 80°C decrease in the PA-6,6 crystallization temperature. A near linear increase in the impact strength of the blends was observed with f-PP incorporations up to 30% of the PP phase. Moreover, blends containing 30% f-PP demostrated impact properties approaching that of pure PA-6,6.     

Hemolysis test of a centrifugal pump in a pulsatile mode: the effect of pulse rate and RPM variance

Centrifugal pumps are generally employed as nonpulsatile blood flow pumps; however, these pumps can produce pulsatile flow by periodically alternating the impeller rotation speed. This study investigates blood trauma due to the effect of pulse frequency and various ranges of pump speed. The hemolysis tests were conducted using the Gyro C1E3 pump. The study was divided into the following categories: Group 1 in a nonpulsatile mode; Group 2 operated at 40 bpm with 30% of speed variance; Group 3, 60 bpm with 30% of speed variance; Group 4, 40 bpm with 70% of speed variance; and Group 5, 60 bpm with 70% of speed variance. A flow rate of 3 L/min and a total pressure head of 200 mm Hg were employed in all groups to simulate a percutaneous cardiopulmonary support condition. There were no significant differences in the hemolysis levels among Groups 1, 2, and 3. However, Groups 4 and 5 exhibited a significantly higher hemolysis rate compared to the other groups. These results indicate that a high rate of speed variance increases hemolysis; however, a range of less than 30% does not affect hemolysis. The pulse rate has no significant effect on hemolysis. In conclusion, the higher speed variance increases the hemolysis level when a pulsatile mode is applied with a centrifugal pump at the given test conditions. However, a speed variance of less than 30% or a pulse rate of less than 60 bpm does not affect hemolysis.     

How Do Logical Inference Rules Help Construct Social Mental Models?

Starting from recent approaches in mental model research, it is argued that (1) logical inference rules are used in order to construct mental cliques from learned sentiment relations, and (2) social context cues (operationalized as primes) play a crucial role in activating such rules. Transitivity and antitransitivity are taken as examples, and are shown as core constituents of such models. In a first experiment, priming was achieved by announcing the sorting of fictitious persons in either two or three cliques. Thirty-one subjects studied eight sets of sentiment relations among these persons that either did or did not satisfy their primed clique expectations. They showed longer study times and more requests for additional information in the case of inconsistent fits between prime and set. Their sorting solutions also showed clear priming effects. A second experiment (n = 30) showed that when undergoing a recognition test after seeing the relation sets, subjects tended to confuse model-consistent distractors with information they had actually seen. In a third experiment (n = 30) the results from Experiment 1 were replicated using more realistic learning materials.     

Sterility of ophthalmic drugs dispensed from spray bottles

We attempted to show that surgical treatment of breast cancer, including axillary lymph node dissection with or without concomitant partial mastectomy (ALND), simple mastectomy (SM), and modified radical mastectomy (MRM) can be performed safely in an outpatient setting. The records of 100 consecutive women undergoing definitive breast cancer surgery by the authors between August 1994 and July 1996 were retrospectively reviewed. Average age was 54 +/- 10 years. Fifty patients were discharged the day of surgery, 44 were hospitalized, and 6 remained 2 or more days postoperatively. Outpatients were more likely to have undergone ALND or SM (42 versus 23 procedures) and more often completed surgery in the morning (36 versus 12); P < 0.05. Eight patients of 35 with MRM were discharged the same day. One patient was readmitted with a wound infection. There were no major complications or deaths. Ninety-four per cent of patients were discharged within 23 hours of surgery; half were discharged the same day. No complications occurred in outpatients, and there were no readmissions. For patients admitted overnight, no complications were detected during the overnight hospital stay. In conclusion, breast cancer surgery, from ALND to SM or MRM, can be safely and comfortably performed on an outpatient basis.     

Interaction of Interceed oxidized regenerated cellulose with macrophages: a potential mechanism by which Interceed may prevent adhesions

OBJECTIVE: The objective of the study was to determine whether Interceed oxidized regenerated cellulose (Johnson & Johnson Medical, Arlington, Tex.), because of its polyanionic nature, may compete for the macrophage scavenger receptor. STUDY DESIGN: RAW macrophages were incubated with Interceed oxidized regenerated cellulose and known scavenger receptor ligands. The production of interleukin-1beta by mouse peritoneal macrophages was measured in the presence of Interceed cellulose. RESULTS: When macrophages were incubated with Interceed cellulose, increasing concentrations inhibited the uptake of fluorescent acetyl low-density lipoprotein. In the presence of Interceed cellulose there was a decrease in the production of interleukin-1beta by mouse macrophages. CONCLUSION: These results suggest that the interaction of Interceed oxidized regenerated cellulose with macrophages with scavenger receptors may result in a decreased secretion of matrix components, inflammatory mediators, and cellular growth factors. Thus Interceed cellulose may function as a biologic barrier in preventing adhesions.     

Stress urinary incontinence. Our experience with its treatment using the transvaginal colposuspension technique (Raz I and II)

Presentation of our experience in the surgical treatment of urinary stress incontinence, with transvaginal colposuspension techniques, specifically those described by S. Raz and known as Raz I and Raz II. Over a 24-month period, 25 transvaginal colposuspensions (22 Raz I and 3 Raz II) were performed. The results achieved were 21 patients (84%) have recovered, while 4 (16%) remain incontinent, 3 of them referring improvement and 1 without improvement, after a follow-up of 12 to 36 months. With regard to complications, there has been 5 cases (20%) of postoperative retention, one vesical perforation while passing the needles, and a vesicle perforation during vaginal dissection of the retropubic space.     

Resolution of a left ureteral stone using electrohydraulic lithotripsy in a thoroughbred colt

A 3-year-old Thoroughbred colt was presented for evaluation of azotemia and anorexia. Physical examination revealed a ureterolith in the left ureter, approximately 10 cm from the bladder, which was thought to obstruct urine flow by approximately 90% when viewed cystoscopically. Ultrasonographic examination of both kidneys revealed indistinct corticomedullary junctions, and the right kidney was more hyperechoic. A percutaneous biopsy of the right kidney revealed chronic interstitial nephritis with marked interstitial medullary fibrosis. Medical therapy consisting of IV fluids, sodium chloride PO, and ammonium chloride PO was initiated. Ureteroscopic electrohydraulic lithotripsy via a perineal urethrostomy was used to successfully remove the stone. Klebsiella oxytoca, which responded to oral enrofloxacin therapy, was cultured from the urine after surgery. Azotemia resolved and the horse resumed training.