Transport and electrical properties of cryogenic thermoelectric FeSb2: the effect of isoelectronic and hole doping.

Thermoelectric materials operating at cryogenic temperatures are in high demand for efficient cooling and power generation in applications ranging from superconductors to quantum computing. The narrow band-gap semiconductor FeSb2, known for its colossal Seebeck coefficient, holds promise for such applications, provided its thermal conductivity value can be reduced. This study investigates the impact of isoelectronic substitution (Bi) and hole doping (Pb) at the Sb site on the transport properties of FeSb2, with a particular focus on thermal conductivity (κ). Polycrystalline FeSb2powder, along with Bi- and Pb-doped samples, were synthesized using a simple co-precipitation approach, followed by thermal treatment in an H2atmosphere. XRD and SEM analysis confirms the formation of the desired phase pre- and post-consolidation using spark plasma sintering. The consolidation process resulted in a high compaction density and the formation of submicrometer-sized grains, as substantiated by electron backscattered diffraction analysis. Substituting 1% of Bi and Pb at the Sb site successfully suppressed the thermal conductivity (κ) from ∼15 W (m·K)-1in pure FeSb2to ∼10 and ∼8.7 W (m·K)-1, respectively. Importantly, resistivity measurements revealed a metal-to-insulator transition at around 6.5 K in undoped FeSb2and isoelectronically Bi-substituted FeSb2, suggesting the existence of metallic surface states and provides valuable evidence for the perplexing topological behavior exhibited by FeSb2.

The effect of antisite disorder on magnetic and exchange bias properties of Gd-substituted Y2CoMnO6double perovskite.

Combining experimental investigations and first-principles density functional theory (DFT) calculations, we report physical and magnetic properties of Gd-substituted Y2CoMnO6double perovskite, which are strongly influenced by antisite-disorder-driven spin configurations. On Gd doping, Co and Mn ions are present in mixed-valence (Co3+, Co2+, Mn3+and Mn4+) states. Multiple magnetic transitions have been observed: (i) paramagnetic to ferromagnetic transition is found to occur atTC= 95.5 K, (ii) antiferromagnetic transition atTN= 47 K is driven by3d-4fpolarization and antisite disorder present in the sample, (iii) change in magnetization belowT⩽20 K, primarily originating from Gd ordering, as revealed from our DFT calculations. AC susceptibility measurement confirms the absence of any spin-glass or cluster-glass phases in this material. A significantly large exchange bias effect (HEB= 1.07 kOe) is found to occur below 47 K due to interfaces of FM and AFM clusters created by antisite-disorder.

e-TEP repair for midline primary and incisional hernia: technical considerations and initial experience.

INTRODUCTION: The Enhanced-View Totally Extra Peritoneal Rives-Stoppa (e-TEP-RS) Technique for the repair of large, complex, ventral abdominal hernias has gained popularity especially in overcoming the disadvantages with Intra Peritoneal Onlay Mesh (IPOM) repairs and to enable siting of a large prosthetic mesh in an anatomical plane distinct from the abdominal cavity and its contents. Evolving variations of the original technique have allowed the definitive repair of such defects in a reproducible manner. We present our initial experience of this approach and detailed steps of our native technical modifications in overcoming the challenges in performing this complex and potentially challenging procedure. MATERIALS AND METHODS: This is a retrospective review of the clinical data of midline, large, complex, ventral abdominal hernia patients who underwent e-TEP-RS with and without Transversus Abdominis Release (TAR). Patients, with or without Diastasis of Rectus Abdominis Muscle (DRAM) were included. Key outcomes measured were post-operative pain, operative morbidity, readmission, Quality of Life (QoL), hernia recurrence. RESULTS: A total of 58 midline, ventral abdominal hernia patients who underwent e-TEP-RS with and without Transversus Abdominis Release (TAR), between March 2018 and December 2019 were studied. Mean defect area was 41.0 ± 28 cm2 and the mean mesh surface area was 473.5 ± 165 cm2. e-TEP-RS was done in 35 cases, e-TEP RS TAR in 15 cases and e-TEP-RS with e-TEP inguinal in 08 cases. There was no intraoperative morbidity. Mean duration of surgery was 156.2 ± 40 min and mean blood loss was 40.5 ± 26 cc. The CCS QoL scores improved from 34.6 (± 2) pre-operatively to 27.2 (± 4) at the end of 6 months. One patient had a supra-umbilical recurrence following bilateral TAR over the superior edge of the mesh. Follow-up ranged from 6 to 22 months, with a mean of 14 months. Major complications (n = 12; 20.7%) were seroma formation and prolonged ileus. CONCLUSION: The e-TEP-RS technique for large, complex, midline, ventral abdominal hernias can be used with excellent results and acceptable morbidity. This technique is technically challenging and should be mastered in relatively smaller ventral hernias to achieve good results before attempting it in larger, complex ones.

Study of short range correlations and two-fold spin reorientation in NdFe0.5Mn0.5O3.

Detailed powder neutron diffraction studies as a function of temperature is performed on NdFe0.5Mn0.5O3 in the temperature range 400-1.5 K. Diffused magnetic scattering is observed due to three dimensional short range ordering (SRO), between Fe3+/Mn3+ spins, over the whole temperature range 400-1.5 K. The presence of SRO is independent of long range ordering (LRO) in this compound which has never been observed in any Fe3+/Mn3+ based compounds. Further, in this compound two-fold spin reorientation is discussed in the temperature range 300-1.5 K. Development of long range ordering at 300 K is due to the mixture of Γ4 and Γ1 magnetic structure, not like other orthoferrites which have Γ4 structure at 300 K. This occurs due to the presence of large single ion anisotropy of Mn3+ ions. Volume fraction of Γ4 decreases with temperature leading to pure Γ1 magnetic structure in the temperature range 150-90 K. Another spin reorientation of Fe3+/Mn3+ spins occurs from Γ1 to Γ2 in the temperature range 70-25 K.

An experimental and theoretical study of magnetocaloric effect in Nd0.5Dy0.5FeO3.

A significant magnetocaloric effect (MCE) has been revealed in our investigation on polycrystalline Nd0.5Dy0.5FeO3 below 30 K. Observed magnetization of the system at low temperature is 32% higher than the expected average magnetization of NdFeO3 and DyFeO3. Such an enhancement in the magnetization led to a large change in magnetic entropy (10.4 Jkg-1 K-1) at 4 K. The observed entropy change is remarkable considering the higher natural abundance of Nd compared to that of Dy and negligible MCE seen in case of NdFeO3. Theoretical calculations performed using mean-field approximation and Monte Carlo simulations on an Ising type spin model indicate that the high magnetocaloric effect is caused primarily by the ordering of rare-earth ions in C-type antiferromagnetic state in presence of molecular exchange field created by Fe ions.

Practical consensus recommendations regarding role of mastectomy in metastatic breast cancer.

Whether to recommend mastectomy in metastatic disease or not has been a matter of debate. Is local therapy, such as mastectomy, of any benefit in advanced breast cancer is the main question. This expert group used data from published literature, practical experience and opinion of a large group of academic oncologists to arrive at these practical consensus recommendations for the benefit of community oncologists.

Prevalence of ocular morbidity in school going children in West Uttar Pradesh.

AIM OF THE STUDY: This study aims to evaluate the prevalence and to make a comparison between the ocular morbidity pattern in school going children of urban and rural areas of West Uttar Pradesh. MATERIALS AND METHODS: A school-based cross-sectional study design was adopted to examine children aged 5-15 years in randomly selected urban and rural schools of West Uttar Pradesh from June 2012 to August 2014. An optometrist did the vision and refraction, and a detailed ophthalmic examination was done by an ophthalmologist. Children needing further assessment were referred to a higher center. Interpretation and analysis of the data were done using Epi Info Software and t-test. RESULTS: A total of 4838 students (2271 males and 2567 females) were screened. The prevalence of ocular morbidity was 29.35% (28.65% urban, 30.05% rural). Refractive error (17.36%) was the major cause of ocular morbidity followed by convergence insufficiency (2.79%), blepharitis (2.11%), Vitamin A deficiency (2.09%), allergic conjunctivitis (1.92%), bacterial conjunctivitis (0.95%), amblyopia (0.41%), stye (0.31%) and squint (0.27%). There was an increase in ocular morbidity with age, especially in refractive error and convergence insufficiency. On comparing urban and rural schools, Vitamin A deficiency showed a significantly higher prevalence (P < 0.05%) in the rural (3.03%) as compared to the urban sector (1.15%). The prevalence of visual impairment was 4.9/1000 children, and prevalence of blindness was 0.62/1000 children. CONCLUSION: This study was the first of its kind in West Uttar Pradesh, reporting a considerable high prevalence (29.35%) of pediatric ocular morbidity, which was more in rural as compared to the urban sector. Since most of this morbidity is either preventable or treatable, school screening forms an effective method to reduce this load.

Phaco-nucleotomy techniques in management of pseudoexfoliation syndrome.

INTRODUCTION: Pseudoexfoliation syndrome is a common clinically important systemic condition characterized by the pathological production and accumulation of an abnormal fibrillar extracellular material in many intraocular and extra ocular tissues. Many studies have shown that pseudoexfoliation syndrome patients have higher rates of intraoperative complications during cataract surgery compared to the patients without it. OBJECTIVES: To compare Phaco-chop and Divide and Conquer techniques of phacoemulsification, in the management of pseudoexfoliation syndrome in terms of intraoperative complications. MATERIALS AND METHODS: It is a hospital based prospective study of 90 patients with cataract and pseudoexfoliation syndrome attending ophthalmology outpatient department in our hospital. RESULTS: The mean age of patients in the study was 61.7 years with equal number of unilateral and bilateral cases. Intra operative complications noted in vertical chopping technique was only pupil constriction in 6.7%, no other complications were seen in this technique, whereas in horizontal chopping, 13.3% had pupil constriction, 6.7% had difficulty in chopping, 3.3% had zonular dehiscence and 3.3% had posterior capsular rent . In divide and conquer technique 16.7% had pupil constriction, 10% had difficulty in trenching, 3.3% had posterior capsular rent. Almost all the patients (97.8%) were implanted with intraocular lens after employment of various surgical modifications. CONCLUSION: Vertical chopping techniques scores over horizontal chopping and divide and conquer technique of phacoemulsification with good surgical outcome because of less complications.

Assessment of tear secretions in healthy Indian volunteers.

Dry eye syndrome is currently seen with increasing frequency throughout the world including India. An evaluation of tear physiology in the form of tear secretion and tear film stability is the most important aspect of dry eye diagnosis. The aim of this study is to investigate the age and gender related changes in the result of these tear function tests (Schirmers Test and Tear Break up time) in normal Indian population. This cross- sectional observational study included 120 normal subjects (60 Male and 60 females) with no ocular symptoms or ocular surface disorders. Schirmer and tear film break-up time tests were assessed in both eyes of each subject. The study subjects were divided into 4 groups according to their ages (<20 y, 20-40 y, 41-60 y and >60 y) each group was composed of 60 eyes of 30 subjects (15 male and 15 female subjects). The One way ANOVA test and the Statagraphic software was used for statistical analysis. We detected a statistically significant decline in both the tear function tests with increasing age. Tear function tests did not show statistically significant difference according to sex. This study suggests that the age of subjects should be taken into consideration in the evaluation of tear function test results. It is also revealed that Indian population values are different from Caucasian and Chinese values. We propose age specific cut off values of tear function tests in Indian population to aid in the diagnosis of dry eye in Indian conditions.

Spontaneous rupture of lens capsule with dislocation of nucleus in hypermature cataract.

We report a case of spontaneous rupture of the lens capsule in a woman with hypermature cataract, who presented to us with nucleus dislocation in the posterior chamber of her left eye. The capsule had ruptured inferiorly and the nucleus had slided out of it. The anterior chamber was quiet; and no sign of uveitis was noted. She underwent nucleus extraction and IOL implantation in the sulcus. Spontaneous rupture of the anterior lens capsule that leads to dislocation of the nucleus is a rare complication of hypermature cataracts.

Strain-induced ferromagnetism in antiferromagnetic LuMnO3 thin films.

Single phase and strained LuMnO(3) thin films are discovered to display coexisting ferromagnetic and antiferromagnetic orders. A large moment ferromagnetism (≈1µ(B)), which is absent in bulk samples, is shown to display a magnetic moment distribution that is peaked at the highly strained substrate-film interface. We further show that the strain-induced ferromagnetism and the antiferromagnetic order are coupled via an exchange field, therefore demonstrating strained rare-earth manganite thin films as promising candidate systems for new multifunctional devices.

Conjunctival impression cytology in computer users.

INTRODUCTION: It is known that the computer users develop the features of dry eye. OBJECTIVE: To study the cytological changes in the conjunctiva using conjunctival impression cytology in computer users and a control group. MATERIALS AND METHODS: Fifteen eyes of computer users who had used computers for more than one year and ten eyes of an age-and-sex matched control group (those who had not used computers) were studied by conjunctival impression cytology. RESULTS: Conjunctival impression cytology (CIC) results in the control group were of stage 0 and stage I while the computer user group showed CIC results between stages II to stage IV. Among the computer users, the majority ( > 90 %) showed stage III and stage IV changes. CONCLUSION: We found that those who used computers daily for long hours developed more CIC changes than those who worked at the computer for a shorter daily duration.

Magnetic proximity effect in YBa2Cu3O7/La(2/3)Ca(1/3)MnO3 and YBa2Cu3O7/LaMnO(3+δ) superlattices.

Using neutron reflectometry and resonant x-ray techniques we studied the magnetic proximity effect (MPE) in superlattices composed of superconducting YBa2Cu3O7 and ferromagnetic-metallic La0.67Ca0.33MnO3 or ferromagnetic-insulating LaMnO(3+δ). We find that the MPE strongly depends on the electronic state of the manganite layers, being pronounced for the ferromagnetic-metallic La0.67Ca0.33MnO3 and almost absent for ferromagnetic-insulating LaMnO(3+δ). We also detail the change of the magnetic depth profile due to the MPE and provide evidence for its intrinsic nature.

Alport Syndrome: case report and review of ocular manifestations.

BACKGROUND: Alport Syndrome is an uncommon disease. CASE: We report a case of a young Indian male who presented with the characteristic ocular findings and systemic features of Alport Syndrome. CONCLUSION: Any young patient with a chronic renal disease should have a careful ophthalmologic examination for Alport Syndrome.

Cavernous lymphangioma of eyelid - a rare case report.

BACKGROUND: Lymphangioma is a lymphatic malformation, a benign proliferation of lymph vessels. CASE: We hereby present a case of eyelid lymphangioma of cavernous type in a twelve year old male patient. This is a very uncommon site for this type of lymphangioma.

Dimensionality control of electronic phase transitions in nickel-oxide superlattices.

The competition between collective quantum phases in materials with strongly correlated electrons depends sensitively on the dimensionality of the electron system, which is difficult to control by standard solid-state chemistry. We have fabricated superlattices of the paramagnetic metal lanthanum nickelate (LaNiO(3)) and the wide-gap insulator lanthanum aluminate (LaAlO(3)) with atomically precise layer sequences. We used optical ellipsometry and low-energy muon spin rotation to show that superlattices with LaNiO(3) as thin as two unit cells undergo a sequence of collective metal-insulator and antiferromagnetic transitions as a function of decreasing temperature, whereas samples with thicker LaNiO(3) layers remain metallic and paramagnetic at all temperatures. Metal-oxide superlattices thus allow control of the dimensionality and collective phase behavior of correlated-electron systems.

Evidence of a precursor superconducting phase at temperatures as high as 180 K in RBa2Cu3O(7-δ) (R=Y, Gd, Eu) superconducting crystals from infrared spectroscopy.

We show that a multilayer analysis of the infrared c-axis response of RBa2Cu3O(7-δ) (R=Y, Gd, Eu) provides important new information about the anomalous normal-state properties of underdoped cuprate high temperature superconductors. In addition to competing correlations which give rise to a pseudogap that depletes the low-energy electronic states below T*≫T(c), it enables us to identify the onset of a precursor superconducting state below T(ons)>T(c). We map out the doping phase diagram of T(ons) which reaches a maximum of 180 K at strong underdoping and present magnetic field dependent data which confirm our conclusions.

Magnetic properties of silica coated spindle-type hematite particles.

Magnetic properties of particles are generally determined from randomly oriented ensembles and the influence of the particle orientation on the magnetic response is neglected. Here, we report on the magnetic characterization of anisotropic spindle-type hematite particles. The easy axis of magnetization is within the basal plane of hematite, which is oriented perpendicular to the spindle axis. Two standard synthesis routes are compared and the effects of silica coating and particle orientation on the magnetic properties are investigated. Depending on the synthesis route we find fundamentally different magnetic behavior compatible with either single domain particles or superparamagnetic sub-units. Furthermore, we show that silica coating reduces the mean blocking temperature to nearly room temperature. The mechanical stress induced by the silica coating appears to reduce the magnetic coupling between the sub-units.