Investigations of surface related electronic properties in SmB6 and LaAlO3SrTiO3 heterostructures

This dissertation reports research performed on two types of two-dimensional systems: SmB6 and LaAlO3/SrTiO3 (LAO/STO). SmB6 has been proposed to be a topological Kondo insulator at low temperature. In order to understand carriers/ lattice dynamics and their interactions, femtosecond pump-probe spectroscopy is performed in SmB6 single crystals and thin lms at variable temperatures. The collective oscillation modes in GHz - THz and the change of carrier relaxations is observed as a function of temperature. From the temperature dependent results for d hybridization, opening of the hybridization gap, \phonon bottleneck , and th possible topological surface state formation is revealed. The topological surface state should support helical Dirac dispersion with momentum-spin lockage. This dissertation reports on current injection in SmB6 thin lm with circularly polarized light at oblique incidence. This spin polarized photocurrent is concluded to be a direct result of spin momentum lockage in SmB6. LAO/STO interface shows 2-dimensional electron gas (2DEG) at the interface when the thickness of LAO is more than 3 unit cell. Carrier properties at the LAO/STO interfaces are highly sensitive to the top surface termination of LAO. The spontaneous dissociation of water on LAO surface is systematically studied by density functional theory and experimental surface characterizations. Extrinsic effects from surface adsorbates were often ignored in the previous studies of the 2DEG. From the experiments, it is found that the dissociated water molecules, especially the surface protons, strongly aect the interface density of states, electron distributions and lattice distortions. The investigations also reveal the importance of additional molecular water layers. These additional water layers, through hydrogen bonds, provide an energetically feasible pathway for manipulating the surface-bonded protons and thus, the interface electrical characteristics

Vision screening among hearing-impaired school children in Biratnagar, Nepal

Background: The prevalence of hearing impairment in Nepal is 16.5%, affecting approximately 2.71 million people. Deaf children are visually dependent, and even a mild refractive error may cause visual discomfort. The goal of this study was to determine the need for vision screenings in schools for the hearing impaired in Biratnagar, Nepal. Methods: A cross-sectional study was conducted with permission from Birat Deaf Secondary School, Biratnagar, Nepal. A total of 130 hearing-impaired students were examined. Non-invasive, comprehensive optometric examinations were performed to detect visual disorders. When a more detailed evaluation was needed, the students were referred to the Pediatric Ophthalmology Department, Biratnagar Eye Hospital Biratnagar, Nepal. Results: Of the 130 hearing-impaired students, 58 (44.6%) were male and 72 (55.4%) were female. The mean ± standard deviation of age was 16.03 ± 3.8 years (range 6–25 years). Twenty-one (16.1%) students had refractive errors: 13 (10%) had myopia, 7 (5.4%) had hyperopia, and 1 (0.8%) had anisometropia. In the cover test, 88 (67.7%) had orthophoria, 19 (14.6%) had exophoria, 11 (8.5%) had esophoria, 5 (3.85%) had exotropia, and 3 (2.3%) had esotropia. Cover tests were not performed in 4 (3.1%) students, as they were unable to fixate due to nystagmus or decreased vision. On ocular examination, 20 (15.3%) students had anterior segment abnormalities, including lid abnormality, conjunctivitis, Bitot’s spots, pterygium, corneal opacity, and lenticular opacity. Posterior segment or retinal abnormalities were found in four students with one having Usher syndrome. Color vision defects, nystagmus, and amblyopia were found in 8 (6.1%), 2 (1.5 %), and 1 (0.8%), respectively. Conclusions: The findings of the present study reflect the need of periodic vision screenings in schools for the hearing impaired in Nepal. These children are at a high risk of vision impairment. How to cite this article: Sah SK, Thakur R, Adhikari PR. Vision screening among hearing-impaired school children in Biratnagar, Nepal. Med Hypothesis Discov Innov Optom. 2021 Spring; 2(1): 36-40. DOI: https://doi.org/10.51329/mehdioptometry123 &nbsp

Awareness regarding radiation knowledge among clinicians practicing in Bharatpur, Nepal

The major imaging tools used in diagnostic radiology is based on the use of ionizing radiation. Ionizing radiation can be harmful to health, so before referring an examination in diagnostic radiology, clinicians must be aware of its harmful effects and a justified referral guideline should be followed.  A cross-sectional study was carried out among clinicians who are not radiation professionals but do use ionizing radiation as part of their work to assess awareness regarding radiation protection and their current practice. The researcher was directly engaged in data collection using a self-administered semi-structured questionnaire. The findings of the study are presented in the socio-demographic characteristics of respondents, current practice of respondents and knowledge regarding radiation protection. The result of this study demonstrated that despite the importance of radiation and its consequent hazards, the level of knowledge among referring clinicians is only 52.08% and their current practice is 60.55%. The difference in the mean score of knowledge and practice might have resulted due to clinician’s habituation with the practice but they have not updated themselves regarding radiation protection. Also, the study revealed that there is no significant (p>0.05) difference in knowledge level of physicians practicing in different hospitals. But the mean difference in practice scores of different hospitals is significant (p<0.05) i.e. a hospital with a large volume of radiological investigations (in our context a specialized cancer hospital) had better practice as compared to other hospitals. We find that an awareness of the hazardous imaging modalities due to radiation safety, its biological effects, referral practice and its perilous consequences is lacking. The deficiency in knowledge of clinicians might alter the expected benefits, compared to the risk involved, and can cause erroneous medical diagnosis and radiation hazard. Therefore, this study emphasizes the need for all clinicians to update themselves with the appropriate knowledge and current practice about ionizing and non-ionizing radiation

Ocular dominance and refractive error: a cross-sectional study of 400 individuals at a tertiary eye hospital in eastern Nepal

Background: Ocular dominance is the consistent preference of using one eye over the other during visual processing, a phenomenon analogous to hand dominance. Ocular dominance often aligns with the eye delivering clearer vision, but does not always correspond to superior visual acuity or refractive status. Mechanisms underlying ocular dominance remain unclear, particularly in individuals whose refractive errors have remained uncorrected since childhood. In this study, we investigated ocular dominance patterns and their association with refractive error and handedness in individuals without early optical correction. Methods: In this cross-sectional study, we recruited individuals aged 16–40 years with refractive errors, who had no history of spectacle use since childhood, from Biratnagar Eye Hospital, Nepal. Participants underwent anterior and posterior segment examinations using slit-lamp, followed by non-cycloplegic retinoscopy and subjective refraction. Ocular dominance was assessed using the Hole-in-the-Card (Dolman’s) and Miles tests. Hand dominance was determined through standardized questioning and observation during tasks. Spherical equivalents (SEQ) were calculated, and anisometropia was defined as an interocular refractive difference equal or greater than 1.00 D. Results: Four hundred participants (mean [standard deviation, SD] age 26.1 [6.0] years; 61.3% males) were assessed for ocular and hand dominance. Refractive error SEQ ranged from +9.25 D to –13.50 D (mean [SD] –1.75 [2.46] D). Myopia was most common among students (n = 93, 23.3%) and least common among tailors (n = 14, 3.5%). The most frequent dominance pattern was right-hand combined with right-eye dominance (n = 328, 82%). A strong, statistically significant association was found between ocular and hand dominance (P < 0.01; Cramer’s V= 0.73). Moderate but statistically significant associations were observed between refractive error type and both ocular (P < 0.01; V = 0.25) and hand dominance (P < 0.01; V = 0.21). The dominant eye was not always the eye with better visual acuity. Among the 103 individuals with anisometropia (25.8%), ocular dominance was not consistently accompanied by either the higher refractive error or better visual acuity. Conclusions: In this study, we demonstrated a strong and statistically significant association between ocular and hand dominance, suggesting existence of a significant lateralization pattern among individuals with refractive error who had no history of spectacle use since childhood. While a right-hand/right-eye dominance pattern was predominant, variations such as cross-dominance and absence of ocular dominance were also observed. A moderate but significant association was found between the type of refractive error and both ocular and hand dominance, indicating that visual and motor lateralization may influence refractive development. The dominant eye did not consistently accompany by better visual acuity or greater refractive error in individuals with anisometropia, underscoring the complexity of ocular dominance and its clinical implications. These findings may aid in understanding visual behavior and inform clinical decisions related to refractive surgeries, amblyopia management, and binocular vision assessments. Further research is needed to explore the underlying neurophysiological mechanisms

Development of Cost Optimized Horizontal Gel Electrophoresis Running Unit for Developing Countries (Nepal)

The use of expensive lab techniques has left many high schools and even university students unacquainted with the basic experimental procedures and protocols in developing country including Nepal. Horizontal gel electrophoresis is one of the expensive protocols, which every student in the laboratory may not get an equal chance to access individually. However, this technique, being indispensable and inevitable in molecular biology principles, is of abounding importance for students to be familiar with. Thus, realizing its importance, we present an extremely simple and inexpensive design of gel-electrophoresis unit, which emulates electrophoresis analysis with the use of nichrome and aluminum wires as a substitute for platinum wires, together with daily used plastic materials. Because of these factors, the approximate cost of unit design is significantly reduced to an amount of 10 USD. The efficiency of the substitute wires was confirmed and it resulted in satisfactory data characterized by good resolution of the DNA fragments. The inexpensive nature, good results and simplicity of the device make it an ideal unit for teaching and learning in developing countries

Synthesis, structural, DFT calculations and biological studies of rhodium and iridium complexes containing azine Schiff-base ligands

The reaction of [Cp*MCl2]2 (M = Rh/Ir) with N-Nʹ azine Schiff-base ligands (L1-L4) leads to the formation of mononuclear cationic half-sandwich complexes having the general formula [Cp*M(L)Cl]+ (1–8), (M = Rh/Ir and L = (2-hydroxy-4-methoxybenzylidene)2- pyridylamidrazone (L1), (2-hydroxybenzylidene)2-pyridylamidrazone (L2), (1-(2-hydroxyphenyl)ethylidene)2-pyridylamidrazone (L3) and (1-phenylethylidene)2-pyridylamidrazone (L4). All these complexes were isolated as their hexafluorophosphate salts and fully characterized by spectroscopic and analytical techniques. The molecular structure of complexes (1), (3), (4), (7) and (8) have been determined by single crystal X-ray crystallographic studies which displayed the coordination of the ligand to the metal in a bidentate N∩N fashion through nitrogen atom of pyridine and one azine nitrogen. The chemo-sensitivity activities of the complexes were evaluated against HT-29 (human colorectal cancer) cell line and non-cancer cell line ARPE-19 (human retinal epithelial cells) which revealed that the complexes are moderately cytotoxic to cancer cells over human cells although complex 5 was the most potent among all the compounds. Theoretical studies carried out using DFT and TD-DFT at B3LYP level shows good agreement with the experimental results

Diversity of wild edible plants, nutrition and phytochemical evaluation of certain plants with ethnobotanical importance from Tinsukia district, Assam, India

The present study was conducted in 2021-2023 and recorded a total of 96 species, out of which 56 % were used as vegetables, 30 % as edible fruits and 7 % as masticatory, spice and condiments. This study also aims to evaluate the nutritionally important minerals concentration and phytochemical constituents of 5 plant taxa, i.e., Sarcochlamys pulcherrima (Roxb.) Gaud., Zanthoxylum oxyphyllum Edgew., Smilax perfoliata Lour., Portulaca oleracea L. and Phlogacanthas thyrsiformis (Hardw.) Mabb.  which are widely used in folk healing practices and folk medicine by the various ethnic communities of Tinsukia district. The concentration of 5 macro minerals Na, K, Ca, Mg and P is in the range of 12.5 -18.4, 90.4 -246.9, 140 -214.3, 84.9 - 112.2, 23.7 - 41.2 mg/100 g respectively. The ratio of K/Na (5.9:1 to13.4:1), Ca/P (4.1:1 to 9.1:1) and K/(Ca+Mg) (0.11:1 to 0.32:1) are found to be adequate ratios ranging from respectively. Microminerals like Fe, Zn, Cu, Mn and Ni are found in the range between 5.90 -16.17, 0.41-0.91, 0.13 -0.32, 0.07 -0.27 and 0.07 - 0.17 mg/100 g respectively. Some of the important phytochemicals are also found to be present in the analyzed plants. The study shows that consumption of these species may be beneficial for maintaining good mineral nutrition among the common people at a minimum cost

Investigating the Causes of Spectacle Non-Tolerance in Patients at a Tertiary Eye Hospital in Nepal

Purpose: To find out the causes of the non-tolerance of spectacles used among the patients visiting Biratnagar Eye Hospital, Nepal.Patients and Methods: This prospective cross-sectional study was conducted among patients visiting the optical department of Biratnagar Eye Hospital, Biratnagar, Nepal. Patients of age more than 20 years who fall under the definition of spectacle non-tolerance were included. Patients’ spectacle intolerance was verified based on the tolerance limit criteria by the American National Standards Institute (ANSI Z80.1-2015).Results:  A total of 8,000 spectacles were prescribed during the 3 months of study period between April to June 2022. Among these prescriptions non-tolerance cases accounted for 104 patients. The mean age of patients was 41.63 ±13.30 year, ranging between 20 and 70 years. From the total population, 61.55% were male. The prevalence of spectacle non-tolerance was 1.3%. The majority of non-tolerance occurred in the 41-50 age group (31.0%). A major cause of non-tolerance to spectacles was dispensing error accounting for 48% of cases, particularly notable among bifocal lens users.Conclusion: It is crucial to exercise careful consideration when prescribing and providing glasses to patients. Practitioners should eliminate transcription errors completely, as they are unacceptable from a professional standpoint. Opticians should diligently verify all essential parameters for glasses and ensure proper alignment both on and off the face. This meticulous approach serves to reduce intolerance and elevate patient satisfaction with their spectacles

Adult Wilms’ Tumor: A Rare Case Report

Wilms’ tumor is one of the most common intraabdominal malignancies among children and treatment protocols have been well studied in this population. The clinical presentation differs between the pediatric and adult populations with adults presenting similar to patients with renal cell carcinoma. Diagnosis is usually made by surgical pathology as imaging cannot differentiate between Wilms’ tumor and other kidney pathologies. In addition to surgical excision, treatment includes systemic chemotherapy and/or radiation. In this case report, we present a patient who underwent successful surgical resection of a 29x24x25 cm right-sided Wilms’ tumor with subsequent chemotherapy and radiation

Neutrophil to lymphocyte ratio predicts short- and long-term mortality following revascularization therapy for ST elevation myocardial infarction

Background: Several inflammation biomarkers have been implicated in the pathogenesis and prognosis of acute coronary syndromes. However, the prognostic role of the neutrophil-lymphocyte white cell interactive response to myocardial injury in predicting short- and long-term mortality after ST elevation myocardial infarction (STEMI) remains poorly defined.Methods: We evaluated 250 consecutive STEMI patients presenting acutely for revascularization to our tertiary care center over 1 year. Patients with acute sepsis, trauma, recent surgery, autoimmune diseases, or underlying malignancy were excluded. Data gathered included demographics, clinical presentation, leukocyte markers, electrocardiograms, evaluations, therapy,major adverse cardiac events, and all-cause mortality.Results: Mean age was 62 ± 15 years, 70.4% of subjects were males while majority (49.4%) were Caucasians. Mean duration of follow-up was 571 ± 291 days (median 730 days). Univariate analysis of several inflammatory biomarkers including C-reactive protein, revealed white cell count (OR = 1.09, p < 0.001) and neutrophil to lymphocyte ratio (NLR) (OR = 1.05, p = 0.011) as predictors of short- and long-term mortality; but not mean neutrophil count (OR = 1.04, p = 0.055) or lymphocyte count alone (OR = 0.96, p = 0.551). Multivariate analysis using backward stepwise regression revealed NLR (OR = 2.64, p = 0.026), female gender (OR = 5.35, p < 0.001), cerebrovascular accident history (OR = 3.36, p = 0.023), low glomerular filtration rate (OR = 0.98, p = 0.012) and cardiac arrest on admission (OR = 17.43, p < 0.001) as robust independent predictors of long-term mortality. NLR was divided into two sub-groups based on an optimal cut off value of 7.4. This provided the best discriminatory cut off point for predicting adverse mortality outcome. Both short-term (≤ 30 days) and long-term (≤ 2 years) mortality were predicted with Kaplan-Meier survival curve separation best stratified by a NLR cut off value of 7.4.Conclusions: NLR based on an optimal cut off value of 7.4, was an excellent predictor of short- and long-term survival in patients with revascularized STEMI and warrants larger scale multi-center prospective evaluation, as a prognostic indicator. NLR offers improved prognostic capacity when combined with conventional clinical scoring systems, such as the Thrombolysis In Myocardial Infarction risk score.