Effects of Posttreatments on the Storage Stability of Reclaimed Rubber

Reclaimed rubber should be considered a source of new material with an economic impact, so the recycling of waste rubber is especially important. In this paper, sulfur-cured waste tire rubber powder is successfully devulcanized in a normal-pressure continuous regeneration system under the application of an activator and aromatic oil. Then, the reclaimed rubber was subjected to further mechanical shearing using a two-roll mill, rubber extruder, and rubber strainer. The effects of the storage time at room temperature on the properties and structure of reclaimed rubber were examined by sol fraction measurement, Mooney viscosity measurement, crosslink density measurement, tensile property testing, and Rubber Process Analyzer (RPA) measurement. The results under the test conditions indicated that different postprocessing operations were not making much difference to the properties of the reclaimed rubber. But the effect of storage time is more significant; the Mooney viscosity value increased from 65 to 90 when the storage period increases to 60 days, the sol fraction decreased, and the crosslink and density storage modulus also increased with increasing storage time due to the slow recombination and aggregation of the molecular fragments with free radicals happening in the reclaimed rubber during the storage.

Twin Caesarean Delivery “En Caul” – A Case Report and Review of Literature

Intact amniotic fluid membranes may serve to protect the extremely fragile preterm infant from some of the mechanical shearing forces caused by strong uterine contraction. A “caul” delivery occurs when part of the amniotic sac is still stuck to the neonate at the time of delivery, usually attached to the cephalic end or podalic end. An “en caul” delivery is a subtype of caul delivery, which occurs when the entire intact amnion (amniotic fluid sac) is delivered with the neonate inside.1,2 This article introduces the technique of “en caul” Caesarean delivery and reviews our experience. Abdominal (or Caesarean) en caul deliveries can be performed intentionally with surgical technique, on contrary to vaginal en caul deliveries, which occur spontaneously; as a result, vaginal en caul deliveries are considered to be rarer though exact statistics are difficult to determine. According to some estimates, caul deliveries would be 1 - 2 %, or roughly 1 in 80,000, of all vaginal deliveries if no membranes were artificially ruptured (ARM / Amniotomy).2,3 Most en caul births are low gravida, premature and low birth weight (LBW). Prematurity is a significant risk factor for various postpartum complications and is hazards. Previous case reports have poorly described pertinent maternal information beyond gestational age at birth (e.g., past medical history, past surgical history, familial history, and demographic data) which could be used to analyse additional risk factors for en caul birth.

A Systematic Literature Review on Traumatic Optic Neuropathy

Traumatic optic neuropathy (TON) is an uncommon vision-threatening disorder that can be caused by ocular or head trauma and is categorized into direct and indirect TON. The overall incidence of TON is 0.7–2.5%, and indirect TON has a higher prevalence than direct TON. Detection of an afferent pupillary defect in the presence of an intact globe in a patient with ocular or head trauma with decreased visual acuity strongly suggests TON. However, afferent pupillary defects may be difficult to detect in patients who have received narcotics that cause pupillary constriction and in those with bilateral TON. Mechanical shearing of the optic nerve axons and contusion necrosis due to immediate ischemia from damage to the optic nerve microcirculation and apoptosis of neurons is a probable mechanism. The proper management of TON is controversial. High-dose corticosteroid therapy and decompression of the optic nerve provide no additional benefit over observation alone. Intravenous erythropoietin may be a safe and efficient treatment for patients with TON.

Molybdenite Flotation in the Presence of a Polyacrylamide of Low Anionicity Subjected to Different Conditions of Mechanical Shearing

Polyacrylamides (PAM) are used as flocculants in the copper-molybdenum mining industry to improve the settling rate of flotation tailings. These types of reagents are recirculated to flotation in the water that is recovered from the thickeners, and as a result of this practice they can cause depression of flotation of some important minerals such as molybdenite. The objective of this work was to study the effect of a PAM of 11.9% of degree of anionicity on the flotation of molybdenite. The effect of the anionic PAM on molybdenite flotation was studied under different levels (three) of flocculant mechanical shearing. The flotation data was discussed along with intrinsic viscosity, adsorption, induction time, and electrophoretic mobility measurements. It was found that the non-sheared PAM (NS–PAM) had the strongest depressing effect on molybdenite flotation, followed by the moderately sheared PAM (MS–PAM). The depressing effect of the strongly sheared PAM (SS–PAM) was negligible. The flotation data correlated with the induction time measurements that showed that molybdenite became more hydrophilic in the presence of the NS–PAM. The SS–PAM has no effect on the induction times. Further work is ongoing to understand the effect of PAM on molybdenite flotation in the presence of clay minerals and different aqueous media.

Hemolytic anemia in native valve infective endocarditis: a rare case report and review of literature.

Hemolytic anemia (HA) is not a common presentation in infectiousendocarditis (IE) and has only been reported in very few cases. Althoughdiseased valves may cause shearing stress that fragments RBCs, similar to thatassociated with mechanical heart valves, an autoimmune hemolytic process hasalso been implicated. We reported a case of patient who had HA secondary toacute IE due to MRSA. The anemia completely resolved after treating the (IE) .The cause was most likely mechanical shearing (schistocytes or fragmentedRBCs present on peripheral smear) by the large vegetation on native valve ;autoimmune hemolysis was considered unlikely in this case due to consistently negative Coombs tests and failure to respond to corticosteroids.

The seepage flow characteristics of hydrophobically associated polymers with different aggregation behaviours in porous media

The polymer solution for oil displacement is subjected to strong shear action in practical application, and this action will affect its percolation characteristics in porous media. The effects of mechanical shearing on the solution properties and seepage characteristics of modified hydrophobically associated polymers and dendrimers with two different aggregation behaviours were studied. The results showed that mechanical shearing did not affect hydrophobic microzones. Polymers can re-associate to restore part of the network structure, thereby improving shear resistance (dendritic hydrophobically associating polymers > hydrophobically modified partially hydrolysed polyacrylamide). Polymers with ‘cluster’ aggregation behaviour enhanced solution performance, enabling them to establish higher resistance coefficient (RF) and residual resistance factor (RRF) in porous media but also bringing about injection difficulties. Increasing the injection rate would increase the injection pressure, but the established RF and RRF showed a downward trend. Mechanical shear pretreatment effectively improved the injectability of the polymer. To achieve polymer injection and flow control, pre-shearing polymer solution and low-speed injection can be used in field applications.