Surface Activated Pyrolytic Carbon Black: A Dual Functional Sustainable Filler for Natural Rubber Composites.

The significant rise in end-of-life tires (ELTs) globally poses immediate environmental and human health risks. Therefore, to promote ELTs recycling and to reduce tire industry carbon emissions, herein we present a facile approach for fine-tuning the interfacial interactions between pyrolytic carbon black (P-CB) obtained from ELTs and natural rubber (NR) matrix using phosphonium-based ionic liquid (PIL). The reinforcing effect of PIL-activated P-CB was studied by replacing the furnace-grade carbon black (N330-CB) with varying PIL and P-CB loadings. Adding PIL improved the filler dispersion and the cross-linking kinetics with a substantially reduced zinc oxide (ZnO) loading. Considering the cross-linking and viscoelastic properties, it was concluded that the composite, P-CB/N330-CB-PIL (1.5)+ZnO (1) with half substitution of N330-CB with P-CB synergistically works with 1.5 phr PIL and 1 phr of ZnO resulting in improved dynamic-mechanical properties with a minimal loss tangent value at 60 °C (tanδ=0.0689) and improved glass transition temperature (Tg =-38 °C) compared to control composite. The significant drop (~29 % lower) in tanδ could reduce fuel consumption and related CO2 emissions. We envisage that this strategy opens an essential avenue for "Green Tire Technology" towards the substantial pollution abatement from ELTs and reduces the toxic ZnO.

Molecular Insights into Antioxidant Efficiency of Melanin: A Sustainable Antioxidant for Natural Rubber Formulations.

N-(1,3-Dimethyl butyl)-N'-phenyl-p-phenylenediamine (6-PPD) is a worldwide antioxidant commonly added to delay the thermo-oxidative degradation of tire rubbers. Unfortunately, 6PPD and its transformation product 6PPD-quinone are toxic to aquatic organisms (e.g., coho salmon). Herein, we explore the free radical scavenging activity and protective mechanism of melanin (MLN) on natural rubber's (NR's) oxidative resistance using molecular dynamics (MD) and quantum mechanical (QM) calculations. The relationship between the molecular structure and the chemical nature of the antioxidant molecules via transition state calculations is explored to unravel the reaction mechanisms of antioxidants interacting with peroxy radicals (ROO·) of NR with the estimation of reaction barriers. Following this, the radical scavenging activity of antioxidants was quantified via a hydrogen atom transfer mechanism and bond dissociation energy calculations. Parallel MD simulations were considered to study the interfacial interactions of antioxidant molecules with polymer chains and fillers with a quantifiable structure-property correlation. Given these results, the nanocomposite (NR-MLN-SiO2) with natural antioxidant melanin manifested outstanding antioxidant properties by preferentially bagging the ROO· radicals, thus improving NR's thermal-oxidative aging relative to 6-PPD. The MD results revealed that the intermolecular interactions at the NR/antioxidant interface benefited the antioxidant MLN to bind tightly to the NR in NR-MLN-SiO2 composite, thus exhibiting improved dispersion, O2 barrier properties, and thermo-oxidative stability, which could extend the service life of NR products (e.g., tires). In addition, as a sustainable antioxidant, MLN could replace toxic antioxidants like 6-PPD. More importantly, the QM/MD simulations provided a fundamental understanding of the mechanistic pathways of antioxidant molecules in NR composites, which are conducive to designing high-performance and sustainable green elastomers.

Magnetic Resonance Spectroscopy: Novel Non-invasive Technique for Diagnosing Brain Tumors.

OBJECTIVE: To determine the accuracy of MR Spectroscopy (MRS) in diagnosing brain tumors. STUDY DESIGN: Analytical study. PLACE AND DURATION OF STUDY: Neurosurgery Department, Jinnah Postgraduate Medical Centre, Karachi, from November 2010 to April 2011. METHODOLOGY: Fifty cases with brain tumors, who presented to Neurosurgery Department of Jinnah Postgraduate Medical Centre, Karachi, during the study period, were included in the study. All patients underwent MRS and later brain. Those with recurrent disease were excluded. Data was collected with the help of proforma. Data was analyzed using SPSS version 16. Comparison of MRS findings and biopsy diagnosis was done. Sensitivity, specificity, negative and positive predictive values (NPV and PPV) were determined keeping histopathology as the gold standard. RESULTS: Out of the 50 patients, there were 20 (40%) females and 30 (60%) males with mean age of 37 ± 13.24 years. The commonest presenting complaint was headache (76%) followed by weakness (62%) and seizures (30%). MRI had diagnosed 27 (51%) as neoplastic lesion. Spectroscopy reported 44 (88%) as neoplasms, while on histopathology, 42 (84%) were confirmed to have neoplasm. The accuracy of MRS was 94%, with 97.6% sensitivity, 71.42% specificity, 95.45% PPV and 83.3% NPV. CONCLUSION: Magnetic resonance spectroscopy can readily help in differentiating neoplasm from non-neoplastic brain tumors, thus an invasive brain biopsy procedure can be avoided.

Intramedullary dermoid cyst with relatively atypical symptoms: a case report and review of the literature.

BACKGROUND: Intraspinal dermoid cysts are rare and benign tumors that occur primarily due to the defective closure of the neural tube, an ectodermal derivative, during the process of development. They are slow-growing tumors manifesting in the second and third decades of life. CASE PRESENTATION: We present here a case of a 14-year-old Sindhi boy with a six-month history of paraparesis of the lower limbs and a progressive loss of power of grade 3/5, and hypoesthesia in the L4/L5 dermatomes of his right lower limb. A plain magnetic resonance imaging scan revealed a well-demarcated intraspinal intramedullary cyst containing an abscess at the level of T12 and L1 causing localized cord compression, which was producing the symptoms. Near total excision of the cyst was successfully performed and was sent for biopsy, which revealed keratinocytes and keratin flakes. With one month of follow-up, along with physiotherapeutic management, the patient gradually improved and was able to walk without support. CONCLUSIONS: Critical evaluation of every case with aggravating symptoms should be carried out, and neurological and radiological examinations should be conducted to ensure the well-being of patients.

Delayed diagnosis of post-traumatic C7 vertebra anterior subluxation with an unusual neurological pattern: a case report.

INTRODUCTION: Post-traumatic subluxations are potentially devastating injuries to the axial skeleton. Of utmost priority are an expedient and timely diagnosis and realignment because of its association with spinal cord and nerve root trauma, which lead to progressive deleterious neurological deficits. A good radiological study of the occipitocervical joint and first thoracic vertebra is key to a successful early diagnosis. However, cases might still fail to be diagnosed, leading to trouble. A case of post-traumatic subluxation at the C7 vertebral level with an unusual neurological pattern is presented here. CASE PRESENTATION: A 35-year-old farmer from the Sindh province of Pakistan presented to our neurology department after a fall 2 months earlier and complained of lower limb pain and difficulty in walking. He had numbness in both of his lower limbs up to his umbilical region, with sparing of bladder function along with intact strength in the upper extremities bilaterally. CONCLUSIONS: Our case highlights the unusual sparing of upper limbs and intact urinary continence with severe lower limb deficits in a 70% subluxation. Our case is unusual because highly detrimental effects such as quadriplegia are expected with such extreme subluxation, but our patient presented with only lower limb deficits. This case serves as a reminder to emergency medicine doctors, spine surgeons, and even radiologists (a) to evaluate spine injuries by using computed tomography in trauma patients to identify artifact around a suspected injury and (b) to be mindful of negative conventional radiographs.