SELECTIVE GROWTH OF CARBON NANOTUBES AND OXIDE NANOWIRES: APPLICATIONS IN SHADOW LITHOGRAPHY AND FABRICATION OF ALIGNED CARBON NANOTUBE MEMBRANES

A promising approach investigated here is to utilize thin film multilayer structures where the thickness of a catalyst layer at an exposed edge of photolithographically defined pattern determines the diameter of the nanotubes/nanowires grown from it. This can in turn be incorporated into photolithographically defined post structures resulting in an array of suspended nanowires for line-of-site shadow lithography. Success of the diameter control approach has been shown by selectively growing carbon nanotubes (CNTs) from narrow lines (12-60 nm) of SiO2, Fe, Ni, Co on micron-scale patterned substrates in a ferrocene or nonferrocene catalyzed CVD process. In addition, the concept has been extended to VS growth of CuO nanowires and VLS growth of ZnO nanowires from an exposed edge in a Al2O3/Cu(40-100 nm)/Al2O3 and Al2O3/Au(10 nm)/Al2O3 thin film multilayer structures. The exposed middle layer of patterned thin-film multilayer acts as a nm-scale wide selective growth area. The resultant CNT/nanowire diameter is directly related to the catalyst/catalyst support size. Growth kinetic studies of CuO nanowires from a thin film multilayer structure indicate diffusion controlled process. Dispersion of CNTs between lithographically defined trenches of width of 200 nm and depth of 500 nm when coupled with line-of-site deposition resulted in nm-scale line underneath the suspended CNT. The width of the resulting shadow is nearly a simple function of CNT/nanowire diameter, incident evaporation angle, and height of CNT above the substrate in a line-of-site evaporation geometry. Another promising approach to control the placement of nanotubes/nanowires is the selective functionalization of only their tips followed by selfassembly onto chemically patterned substrates. Towards this goal, arrays of aligned CNTs were impregnated with polystyrene to form aligned CNT membranes. These CNT membranes were also studied for gas and ionic transport studies. Different functionalization chemistry was performed on each side of the membrane. After dissolution of polymer matrix, a suspension of CNTs with different functionality at each tip was formed, allowing for sophisticated selfassembled architectures

Association of ocular biometric parameters with diabetic retinopathy

Background: To study the association of ocular biometric parameters {Spherical equivalent (SE), Axial length (AL), Anterior chamber depth (ACD) and Corneal curvature (CC)} with diabetic retinopathy (DR) in subjects with Type 2 diabetes mellitus (DM).Methods: This prospective observational study was conducted in the Outpatient Department of Ophthalmology of a tertiary care teaching hospital in North India. The study included 100 subjects having various grades of DR as cases and 100 diabetics without DR as controls. The SE was assessed using objective autorefraction, while AL, CC and ACD were measured using the NIDEK AL SCAN.  International Clinical Diabetic Retinopathy Disease Severity Scale was used for grading of DR.Results: A total of 181 eyes in the study group and 200 eyes in the control group were analysed.  Progressive decrease in the mean AL was observed with the increasing severity of DR (p=0.017). Deeper ACD had a negative correlation with severity of DR (p=0.037). No statistically significant difference was observed for AL and ACD with the incidence of DR (p=0.147 and p=0.091 respectively). Likewise, there was no significant relation of DR with SE or CC.Conclusions: Longer AL and deep ACD were protective against progression to the severe forms of DR. However, there was no correlation of AL and ACD with the incidence of DR. The SE and CC were not found to be significant determinants for either development or severity of DR

An elevated D-dimer value: a burden on our patients and hospitals

With 200,000 annual deaths in the United States due to pulmonary embolism (PE), efficient and accurate diagnosis is mandatory. Since negative D-dimer values are only useful in ruling out PE, elevated values alone should not result in excessive testing. This study assessed the diagnostic and financial yield of the D-dimer in diagnosing PE. This retrospective review of 220 medical records of patients at a South Chicago Community Hospital explored the extent of the work-up following an elevated D-dimer for a suspected PE. Patients were randomly selected with no exclusion criteria. Five of the 118 (4.2%) patients with elevated D-dimer values were diagnosed with a PE. Tests ordered based on elevated D-dimer values were billed for more than $200,000. The current diagnostic approach has been medically and financially inefficient. Patients should not be worked-up for a PE based primarily on an elevated D-dimer value. Two prominent factors, independent of PE, that result in elevated D-dimer values and were pertinent to the studied population, are age and African-American origin. Implementing a scoring system, like the revised-Geneva scale, will establish a better index of suspicion to improve both the physician’s diagnostic approach and the yield of the work-up

Synthesis of Nanoscale Heterostructures Comprised of Metal Nanowires, Carbon Nanotubes, and Metal Nanoparticles: Investigation of Their Structure and Electrochemical Properties

One-dimensional nanoscale heterostructures comprised of multisegment gold-nickel nanowires, carbon nanotube, and nickel nanoparticles were fabricated in a unique approach combining top-down and bottom-up assembly methods. Porous alumina template was utilized for sequential electrodeposition of gold and nickel nanowire segments. This was followed by chemical vapor deposition growth of carbon nanotubes on multisegment gold-nickel nanowires, where nickel segment also acted as a carbon nanotube growth catalyst. The aligned arrays of these gold-nickel-carbon nanotube heterostructures were released from porous alumina template and then subjected to wet-chemical process to be decorated with nickel/nickel oxide core/shell nanoparticles. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy were utilized for morphology, interface, defect, and structure characterization. The electrochemical performance of these heterostructures was studied using cyclic voltammetry method and the specific capacitance of various heterostructures was estimated and compared

Psychosocial Impact of Pandemic and State Imposed Lockdown on Caregivers of Patients Presenting with Respiratory Complaints Mimicking COVID-19: A Short-term Follow-up Study

Introduction: Pandemics and subsequent lockdowns affect mental health of different subgroups of populations. In Coronavirus Disease-2019 (COVID-19), caregivers of those patients who have respiratory complaints is one such subgroup which is more vulnerable to disturbances in mental health, because of the fear that their patient’s respiratory symptoms could be because of COVID-19. Aim: To assess the psychosocial impact of COVID-19 and subsequent state imposed lockdown on the caregivers of patients presenting with respiratory complaints and also to evaluate the effect of relaxation of lockdown after following-up them over a period of time. Materials and Methods: This prospective observational study was conducted in the Department of Pulmonary Medicine, Government Medical College, Patiala, Punjab, India (tertiary care institute), from April 2020 to June 2020. Baseline assessment was done using socio-demographic proforma, lockdown related questionnaire {3 domains, summed as total score (lockdown)}, COVID-19 related questionnaire {total score (COVID-19)} and General Health Questionnaire-12-Hindi version (GHQ-12). Reassessment was done twice i.e., at 11-15 days and 41-45 days after relaxation of lockdown. Quality Of Life (QOL) at first and second follow-up versus prelockdown times (score A and C) and first follow-up versus unlockdown (score B) was also noted. Analysis was conducted using Statistical Package for Social Sciences (IBM, SPSS)version 22.0. Results: Total 65 caregivers were enrolled in the study. Mean age of the participants was 40.2±11.812 years with maximum caregivers 25 (41.7%) aged between 31-40 years. Majority (83.3%) were men. Psychological distress was experienced in 50% of caregivers at baseline and 23.7% caregivers at first follow-up (p-value=0.001). Worry for COVID-19 (p-value=0.035), Domain 1 scores (p-value <0.001), Domain 2 scores (p-value=0.003), Domain 3 scores (p-value=0.001), and Total score lockdown (p-value <0.001) decreased significantly at first follow-up. Mean C score was significantly better than mean A score (p-value <0.001). Baseline psychological distress was significantly more in those with worry for COVID-19 (p-value=0.018), poorer scores of domains 1 (p-value=0.005), domains 2 (p-value <0.001), domains 3 (p-value <0.001), total score (lockdown) (p-value <0.001) and total score (COVID-19) (p-value=0.010). Follow-up psychological distress was more in those with “worry for COVID-19” (p-value <0.001), negative thoughts (p-value=0.001), poorer follow-up scores of three domains, total score (lockdown), mean A, B and C scores (p-value <0.001). Conclusion: Caregivers experienced extreme levels of psychological distress, which decreased, but persisted even after relaxation in lockdown

Accelerating and intensifying manufacturing to enable large-scale supply of a new adenovirus-vectored vaccine within 100 days

The Coalition for Epidemic Preparedness Innovations’ ‘100-day mission’ aspires to launch of a new vaccine within 100 days of pathogen identification. We have previously reported a simple fed batch process and strategy of internationally-distributed manufacturing, which enabled 2 billion doses of the ‘Oxford / AstraZeneca’ adenovirus-vectored COVID-19 vaccine to be produced in less than 600 days from publication of the SARS-CoV-2 genome sequence. The majority was made and used in low and middle income countries. Here, after briefly reviewing that previous work, we will describe efforts to further improve adenovirus manufacturing for response to future pathogen outbreaks and variants. Please click Download on the upper right corner to see the full abstract. Please click Additional File below for the presentation