Porous Structure of ß-Cyclodextrin for CO2 Capture: Structural Remodeling by Thermal Activation.

With a purpose of extending the application of ß-cyclodextrin (ß-CD) for gas adsorption, this paper aims to reveal the pore formation mechanism of a promising adsorbent for CO2 capture which was derived from the structural remodeling of ß-CD by thermal activation. The pore structure and performance of the adsorbent were characterized by means of SEM, BET and CO2 adsorption. Then, the thermochemical characteristics during pore formation were systematically investigated by means of TG-DSC, in situ TG-FTIR/FTIR, in situ TG-MS/MS, EDS, XPS and DFT. The results show that the derived adsorbent exhibits an excellent porous structure for CO2 capture accompanied by an adsorption capacity of 4.2 mmol/g at 0 °C and 100 kPa. The porous structure is obtained by the structural remodeling such as dehydration polymerization with the prior locations such as hydroxyl bonded to C6 and ring-opening polymerization with the main locations (C4, C1, C5), accompanied by the release of those small molecules such as H2O, CO2 and C3H4. A large amount of new fine pores is formed at the third and fourth stage of the four-stage activation process. Particularly, more micropores are created at the fourth stage. This revealed that pore formation mechanism is beneficial to structural design of further thermal-treated graft/functionalization polymer derived from ß-CD, potentially applicable for gas adsorption such as CO2 capture.

Retropharyngeal Tuberculous Abscess: A Rare Cause of Upper Airway Obstruction and Obstructive Sleep Apnea in Children: A Case Report.

Retropharyngeal tuberculous abscess (RPTBA) is a rare manifestation of tuberculosis (TB) even in high TB burden areas. It rarely manifests as a cause of upper airway obstruction and obstructive sleep apnea (OSA) in children with few case reports in the literature. We report a 22 months old toddler who presented with upper airway obstruction and OSA and was diagnosed with RPTBA. The child recovered completely and growing normally after intra-oral aspiration and 6 months of anti-tuberculosis treatment.

EVALUATING THE VALIDITY AND RELIABILITY OF CHEST RADIOGRAPHY IN THE DIAGNOSIS OF TUBERCULOSIS AMONG SMEAR NEGATIVE PULMONARY TUBERCULOSIS PATIENTS.

BACKGROUND: Tuberculosis (TB) is a mycobacterial infection mainly affecting the lungs. Early and correct diagnosis of sputum smear negative patients by chest radiography (CXR) is challenging since it depends on reader's ability to detect abnormal findings and to interpret it correctly. OBJECTIVES: To evaluate the validity and reliability of CXR the diagnosis of TB among smear negative pulmonary tuberculosis (PTB). METHODS: An institutional based cross-sectional study was conducted at seven selected health facilities from October 2011 to September 2012 on 159 adults aged 18 years and above who were newly diagnosed smear negative for PTB patients diagnosed using Chest X-ray (CXR). Morning sputum was collected and cultured from each patient using Lowenstein Jensen media. All the CXRs were revised by senior radiologists in conjunction with the principal investigator. A structured questionnaire was used to collect socio-demographic, clinical and radiological data. Sensitivity and specificity measures of the CXR findings were calculated in comparison to the gold standard sputum culture results. RESULTS: The mean (SD) age of patients involved in the study was 37.1 (16.7), ranging from 18 to 87 years. Of the total 159 smear negative PTB patients, the most common CXR finding was consolidation (40.3%) followed by cavitations (23.9%) and nodular lesions (17.0%). Sputum culture results showed that, 47 (29.6%) were culture positive, 103 (64.7%) were culture negative and 9 (5.6%) were contaminated. About 14% (22/159) of the study subjects were HIV positive. The sensitivity and specificity of CXR findings were 77.1% (37/48) and 36.9% (41/111), respectively. The positive and negative predictive values were 34.6% (3 7/107) and 78.8% (41/52), respectively. CONCLUSION: CXR can be used as supportive investigative modality to diagnose smear negative Pulmonary TB in conditions where TB culture is no more feasible.

Enhancing effect of cobalt phthalocyanine dispersion on electrocatalytic reduction of CO2 towards methanol.

This paper focuses on enhancing the performance of electrocatalytic CO2 reduction reaction (CO2RR) by improving the dispersion of cobalt phthalocyanine (CoPc), especially for the methanol formation with multi-walled carbon nanotubes (CNTs) as a support. The promising CNTs-supported CoPc hybrid was prepared based on ball milling technique, and the surface morphology was characterized by means of those methods such as scanning electron microscopy (SEM), Fourier transform infrared spectrometer (FT-IR) and X-ray photoelectron spectra (XPS). Then, the synergistic effect of CNTs and ball milling on CO2RR performance was analyzed by those methods of cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), gas chromatography (GC), and proton nuclear magnetic resonance spectroscopy (1HNMR). Subsequently, the reduction mechanism of CO2 on ball-milled CoPc/CNTs was revealed based on the DFT calculations. The results showed that the electrocatalyst CoPc/CNTs hybrid prepared with sonication exhibited a conversion efficiency of CO2 above 60% at -1.0 V vs. RHE, accompanied by the Faradaic efficiencies of nearly 50% for CO and 10% for methanol, respectively. The addition of CNTs as the support improved the utilization efficiency of CoPc and reduced the transfer resistance of species and electrons. Then the ball-milling method further improved the dispersion of CoPc on CNTs, which resulted in the fact that the methanol efficiency was raised by 6% and partial current density was increased by nearly 433%. The better dispersion of CoPc on CNTs adjusted the reduction pathway of CO2 and resulted in the enhancement of methanol selectivity and catalytic activity of CO2. The probable pathway for methanol production was proposed as CO2 → *CO2- → *COOH → *CO → *CHO → *CH2O → *OCH3 → CH3OH. This suggests the significance of the ball-milling method during the preparation of better supported catalysts for CO2RR towards those high-valued products.

Chronic intracranial subdural hematoma after spinal anesthesia for a cesarean section: a case report.

BACKGROUND: Subdural hematoma is a rare, potentially devastating, yet curable complication of spinal anesthesia. Differentiation between post-dural puncture headache and subdural hematoma can be difficult, resulting in a delay in diagnosis. CASE PRESENTATION: We present a 28-year-old Ethiopian female patient who underwent elective cesarean section under spinal anesthesia and returned to the emergency department after 1 month with a worsening headache. Brain computed tomography revealed a chronic subdural hematoma with a significant midline shift. The patient recovered completely after surgical evacuation. CONCLUSIONS: A high index of suspicion and close attention to the pattern and characteristics of the headache, coupled with a meticulous neurologic examination and neuroimaging, can help to achieve timely diagnosis of this serious entity. Investigation with head computed tomography or magnetic resonance imaging is vital.

Patterns of lumbar myelographic findings in patients with LBP a 5 years retrospective study at Yehuleshet Higher Clinic, Addis Ababa, Ethiopia.

BACKGROUND: Low back pain (LBP) is usually defined as pain, muscle tension, or stiffness localized below the costal margin and above the inferior gluteal folds, with or without leg pain (sciatica). LBP is a common health problem and the imaging of which need carful clinical diagnostic triage. Most of us will experience at least one episode of LBP during our life. Despite its burden to the health facilities, more than 90% have no identifiable organic cause so their diagnosis is based on exclusion of other specific pathologies. OBJECTIVE: The study asses level of association of LBP and lumbar Myelographic findings in a higher clinic in Addis Ababa and provide baseline information of patterns of lumbar myelographic disease. PATIENTS AND METHODS: This is a retrospective record review of patients with LBP for whom lumbar myelography was done at Yehuleshet Higher Clinic. Data were collected from the clinics record, both hard and soft copy records were used a total of 1688 patients who had lumbar myelography study done for a complaint of LBP in the years from 2002-2008 are included in the study. RESULTS: Among the study subjects 895 (53%) were males and 793 (47%) were females. Mean age was 42.41 +/- 13.22. 1073 (63.6%) had abnormal myelographic findings and the rest 615 (36.4%) had normal lumbar myelography. The commonest abnormality is disc prolapse 36.7% with L4-L5 and L5-S1 being the commonest sites. CONCLUSION: Even if lumbar myelography showed abnormal findings in 63.6% a significant number of the studies (36.4%) were normal indicating lack of optimal clinical triage. Overall in countries like ours, where the recommended primary imaging modality, i.e., MRI is inaccessible and expensive, the value of myelography is unquestionable. RECOMMENDATION: But because of the invasive nature of the examination which also uses radiation, a diagnostic clinical triage should be taken first before subjecting patients to Myelographic procedures. Further studies to assess the positive predictive value of myelography with surgical confirmation are recommended.

Value of baseline radiograph for COVID-19 infected patients

Introduction: A cluster of pneumonia cases of unknown origin was first reported in Wuhan China then the causative pathogen was identified and named severe acute respiratory syndrome coronavirus 2 (SARS-Cov2) and the associated disease was named coronavirus disease 2019 (COVID-19). Chest radiograph has lower sensitivity for the detection of lung abnormalities but it has a role in disease progression and also in the late stages of COVID19. This study aims to evaluate the value of baseline radiographs in COVID-19-infected patients. Method: This is a retrospective study of COVID-19 patients with RT-PCR confirmation who were admitted to Eka Kotebe General Hospital and had baseline chest x-ray between April and May 2020. Baseline chest x-ray of all patients who have confirmed COVID-19 infection was reviewed and analyzed. Result: The study included 355 patients, 224 (63.1%) were male and 131 (36.9%) were female. Patient age ranged from 4 - 82 years with a mean age of 35. Two hundred twelve patients were symptomatic; the rest 143 were asymptomatic. Of the 355 baseline CXR, only 60 (16.9%) had abnormal radiographs and the rest 295 (83.1%) had normal radiographs. A combination of interstitial changes and GGO were the predominant descriptive finding accounting for 33.3% . Conclusion: Even if chest radiographs are important in the workup of patients with COVID-19 infection, the use of baseline radiographs in COVID-19 infection should not be a routine practice. Disease severity and timing of imaging appear to impact the rates of normal baseline imaging.

Thermal air oxidation changes surface and adsorptive properties of black carbon (char/biochar).

In this study, we systematically investigated the effects of thermal air oxidation on the properties of biomass-derived black carbon (BC) made at carbonization temperatures (HTTs) of 300-700°C. BC produced by including air in the carbonization step was found to have a low surface area and underdeveloped pore structure. Substantial changes of BC were observed after post-pyrolysis thermal air oxidation (PPAO). Well-carbonized BC samples made anoxically at relatively high HTTs (600 and 700°C) showed, after PPAO, significant increases in N2 BET surface area (SA) (up to 700 times), porosity (<60Å) (up to 95 times), and adsorptivity (up to 120 times) of neutral organic species including two triazine herbicides and one natural estrogen. Partially carbonized BC made at a lower HTT (300 or 400°C) showed moderate increases in these properties after PPAO, but a large increase in the intensity of Fourier transform infrared spectroscopy bands corresponding to various oxygen-containing functional groups. Well-carbonized BC samples, on the other hand, were deficient in surface oxygen functionality even after the PPAO treatment. Adsorption of the test organic compounds on BC generally trended with BET SA when it was less than 300m2/g, but BET SA was poorly predictive of adsorption when it was greater than 300m2/g. Overall, our results suggest that thermal reactions between molecular oxygen and BC 1) increase surface oxygen functionality more effectively for low-HTT than for high-HTT BC samples; 2) increase SA and porosity (<60Å) especially for high-HTT BC samples; and 3) create new adsorption sites and/or relieve steric restriction of organic molecules to micropores, thereby enhancing the adsorptivity of BC. These results will prove useful not only for understanding the fate of environmental BC but also in devising strategies for improving the practical performance of the engineered form of BC (i.e., biochar).