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Periodic lattice distortion, known as the charge density wave, is generally attributed to electron–phonon coupling. This correlation is expected to induce a pseudogap at the Fermi level in order to gain the required energy for stable lattice distortion. The transition metal dichalcogenide 1T-VSe2 also undergoes such a transition at 110 K. Here, we present detailed angle-resolved photoemission spectroscopy experiments to investigate the electronic structure in 1T-VSe2 across the structural transition. Previously reported warping of the electronic structure and the energy shift of a secondary peak near the Fermi level as the origin of the charge density wave phase are shown to be temperature independent and hence cannot be attributed to the structural transition. Our work reveals new states that were not resolved in previous studies. Earlier results can be explained by the different dispersion natures of these states and temperature-induced broadening. Only the overall size of the Fermi surface is found to change across the structural transition. These observations, quite different from the charge density wave scenario commonly considered for 1T-VSe2 and other transition metal dichalcogenides, bring fresh perspectives toward correctly describing structural transitions. Therefore, these new results can be applied to material families in which the origin of the structural transition has not been resolved. [ABSTRACT FROM AUTHOR]

Here, by using angle-resolved photoemission spectroscopy, we showed that Bi2−xCrxSe3 single crystals have a distinctly well-defined band structure with a large bulk band gap and undistorted topological surface states. These spectral features are unlike their thin film forms in which a large nonmagnetic gap with a distorted band structure was reported. We further provide laser-based high resolution photoemission data which reveal a Dirac point gap even in the pristine sample. The gap becomes more pronounced with Cr doping into the bulk of Bi2Se3. These observations show that the Dirac point can be modified by the magnetic impurities as well as the light source. [ABSTRACT FROM AUTHOR]

Kagome vanadates AV3Sb5 display unusual low-temperature electronic properties including charge density waves (CDW), whose microscopic origin remains unsettled. Recently, CDW order has been discovered in a new material ScV6Sn6, providing an opportunity to explore whether the onset of CDW leads to unusual electronic properties. Here, we study this question using angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM). The ARPES measurements show minimal changes to the electronic structure after the onset of CDW. However, STM quasiparticle interference (QPI) measurements show strong dispersing features related to the CDW ordering vectors. A plausible explanation is the presence of a strong momentum-dependent scattering potential peaked at the CDW wavevector, associated with the existence of competing CDW instabilities. Our STM results further indicate that the bands most affected by the CDW are near vHS, analogous to the case of AV3Sb5 despite very different CDW wavevectors. The authors use angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM) to study the charge density wave (CDW) in the kagome material ScV6Sn6. The ARPES data shows minimal changes to the electronic structure in the CDW state, while STM quasiparticle interference measurements imply a strong reconstruction of the electronic structure in the CDW state. [ABSTRACT FROM AUTHOR]

ABSTRACT Background: The Cotoneaster species are widely used as traditional purposes in different countries including Turkey. Purpose: The study was performed to evaluate the biological and chemical profile of two [...]

Aim: To evaluate the demographic and clinical characteristics of patients who underwent pars plana vitrectomy (PPV) for intraocular lens (IOL) dislocation into the vitreous cavity and the visual and anatomical outcomes of PPV in these patients. Material and Methods: This retrospective study reviewed the files of patients who underwent PPV for IOL dislocation into the vitreous in our clinic between January 2014 and December 2018. Patient age, gender, preoperative and postoperative best corrected visual acuity (BCVA), intraocular pressure (IOP), comorbid ocular pathologies, causes of IOL dislocation, time from IOL dislocation to PPV surgery, surgical methods, and preoperative and postoperative complications were recorded. Results: This study included 15 eyes of 15 patients with IOLs dislocated into the vitreous, of which 5 (33.3%) were female and 10 (66.7%) were male. Mean patient age was 60.8±22.67 (12-94) years. Seven (46.7%) of 15 eyes underwent a secondary IOL implantation in the same session as IOL extraction, whereas eight eyes were planned to undergo a secondary IOL implantation in a second session. Meanwhile, 2 (13.3%) eyes did not undergo IOL implantation. Median preoperative BCVA was 1.7 (0.4-1.92) logMAR and median postoperative BCVA was 0.5 (0-2) logMAR across all patients (p=0.002). After surgery, BCVA was higher in 12 patients (80%), unchanged in 2 patients (13.3%) and lower in one patient (6.7%). In our series, 3 eyes were detected to have preoperative RD and 2 eyes high IOP, whereas one patient showed recurrent RD and 4 eyes showed high IOP postoperatively. Median postoperative BCVA was significantly higher in patients who underwent secondary IOL implantation in a second session than those who underwent IOL implantation in the same session (p=0.035). Conclusion: PPV is a safe method for achieving successful visual and anatomical outcomes in patients with IOL dislocated into the vitreous cavity. In these patients, performing the secondary IOL implantation in a second session can result in a higher final visual acuity. Also, monitoring these complex cases closely is important in order to achieve better visual and anatomical outcomes. [ABSTRACT FROM AUTHOR]

To evaluate the clinical characteristics of patients with lens or lens fragments luxated into the vitreous cavity and the visual and anatomical outcomes of pars plana vitrectomy (PPV) in these patients. This retrospective study reviewed the files of patients who had undergone PPV for lens or lens fragments luxation into the vitreous cavity at the Ophthalmology Department at Inonu University, Faculty of Medicine between January 2014-December 2018. Patient age, gender, preoperative and postoperative best corrected visual acuity (BCVA), intraocular pressure (IOP), anterior segment examination and posterior segment examination findings, preoperative and postoperative complications, and postoperative follow-up times were recorded. This study included 43 eyes of 43 total patients, of which 29 (67.4%) were male and 14 (32.6%) were female. Median patient age was 70 (36-89) years. Median preoperative BCVA was 1.7 (0.5-2) logMAR and median final BCVA was 0.8 (0-2) logMAR (p<0.001). Median preoperative IOP was 16 mmHg and median postoperative IOP was 14 mmHg (p=0.001). Postoperative visual acuity was better in 37 eyes, worse in 4 eyes, and unchanged in 2 eyes. Median postoperative BCVA was significantly better in patients who underwent PPV within three days, while their median preoperative and postoperative IOP were significantly lower (respectively p=0.019, p=0.027, p=0.027). Preoperatively, 13 eyes had shown high IOP, 9 had shown corneal edema, and 3 had shown retinal tears; while, postoperatively, 3 eyes developed retinal detachment and 3 eyes showed high IOP. Median postoperative follow-up time was 8 (3-57) months. PPV achieves successful anatomical and functional outcomes in patients with lens or lens fragments luxated into the vitreous cavity. Early surgical intervention within the first three days can result in better final visual acuity improvement and IOP control. [ABSTRACT FROM AUTHOR]

Rationale: Endophthalmitis is an uncommon but serious ocular infection often resulting in probable visual loss. Bacteroides fragilis is a rare cause of endophthalmitis. Patient concerns: A 46-year-old male patient complained of eye pain and low vision after pars plana vitrectomy. Diagnosis: Bacteroides fragilis endophthalmitis after pars plana vitrectomy was diagnosed. Interventions: Pars plana vitrectomy and silicone oil implantation were performed. Outcomes: Early treatment and choice of tamponade in endophthalmitis after pars plana vitrectomy may possibly prevent evisceration and progression of endophthalmitis. Lessons: Bacteroides fragilis can be seen in cases of endophthalmitis after pars plana vitrectomy. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the anatomical and functional results in cases underwent 23-gauge pars plana vitrectomy (PPV) due to idiopathic stage 4 macular hole. Material and Methods: 17 eyes of 17 patients who underwent PPV due to idiopathic stage 4 macular hole between March 2013 and March 2016 at İnönü University Turgut Özal Medical Center Department of Ophthalmology were included in the study. The medical records of the patients were retrospectively reviewed. Macular hole staging was performed according to biomicroscopic examination and optical coherence tomography findings. Anatomical success was evaluated according to the condition of the macular hole after the surgery and functional success was evaluated according to the visual acuity. Results: 9 (53%) of the cases were females and 8 (47%) were males, the mean age was 66.6 ± 6.6 (55-81). PPV, internal limiting membrane (ILM) peeling and gas tamponade were applied to all cases. The mean follow-up period was 13.9±9.7 (4-30) months. ILM peeling was performed using trypan blue in three (17.6%) of the cases, brillant blue in 4 (23.5%) of the cases and membrane blue in 10 (58.8%) of the cases. Three cases (17.6%) were treated with C3F8 and 14 cases (82.3%) with SF6 gas tamponade. The mean preoperatively best-corrected visual acuity (BCVA) was 0.08±0.06 (0.03-0.2) and the mean postoperatively BCVA was 0.16±0.15 (0.03-0.5). Visual acuity did not change in two eyes (11.7%) and decreased in two eyes (11.7%). Macular hole had not closed in four patients (23.5%). Conclusion: 23 gauge PPV, ILM peeling and C3F8 or SF6 gas tamponade provides anatomical and functional success in the treatment of idiopathic stage 4 macular hole. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the results of phacoemulsification (PE) surgery in completely monocular cases and to emphasize the important points in the pre-, intra- and post-operative periods. Material and Methods: A total of 42 patients who had no light perception in one eye and had underwent PE surgery in the other eye at our clinic between January 2014 and March 2016 were included in the study. The charts of the patients were evaluated retrospectively. The age and gender of the cases, whether there was an additional pathology in the eye undergoing surgery, the reason of visual loss in the other eye, the type of anesthesia used, pre- and post-operative best corrected visual acuity (BCVA) with the Snellen chart, intraocular pressure and intra- and post-operative complications were investigated. Results: There were17 (40.5%) female and 25 (59.5%) male patients with a mean age of 74.2±10.5 (45-93) years. The most common causes of the monocular state were glaucoma, cataract and trauma, the most common accompanying pathologies in the eyes undergoing cataract surgery were glaucoma, zonular weakness and age-related macular degeneration. Mean BCVA was 0.07±0.1 (0.01-0.4) pre-operatively and 0.5±0.3 (0.01-1) post-operatively (p=0.001). The mean follow-up duration was 3.9±5.6 months (1 week to 24 months). The most common post-operative complication was corneal edema. Conclusion: The stress created by cataract surgery on the physician and patient is quite high in monocular cases. However, satisfactory results with PE are obtained in these cases by carefully using pre-, intra- and post-operative methods. [ABSTRACT FROM AUTHOR]

Recent progress in impurity-doped topological insulators has shown that the gap at the Dirac point shrinks with reducing temperature. This is an obstacle for experimental realization of the quantum anomalous Hall effect at higher temperature due to the requirement of a larger energy gap. In order to solve this puzzle, we study the gap at the Dirac point by performing temperature-dependent photoemission spectroscopy and X-ray diffraction experiments in Cr-doped Bi2Se3. Our valence band photoemission study revealed that the gap alters with temperature due to residual gas condensation on the sample surface with cooling. Residual gas on the sample surface creates an electron doping effect that modifies the chemical potential of the system resulting in the change of the gap size with variable temperature. Furthermore, such electron doping can weaken the ferromagnetism and lead to a bulk band contribution in the transport measurements. Therefore, such effects can hinder the existence of the quantum anomalous Hall state at higher temperatures. Hence, this work can pave the way for future studies towards a high-temperature quantum anomalous Hall effect. [ABSTRACT FROM AUTHOR]

Magnetic and dielectric materials can be blended to enhance absorption properties at microwave frequencies, although the materials may have relatively weak attenuation capabilities by themselves. The specific goal of this work is to enhance microwave absorption properties of materials with interesting dielectric behavior by blending them with magnetic materials based on transition metals. The synthesized Mn1-xZnxFe2O4 (x = 0.0 and 1.0) spinel ferrite nanoparticles (MZF NPs) were blended with commercial multi-walled carbon nanotubes (MWCNTs) in various proportions with a binder matrix of paraffin. This simple and efficient process did not cause a significant variation in the energy states of MWCNTs. MZF NPs were synthesized with a citric acid assisted sol-gel method. Their electromagnetic characteristics and microwave absorption properties were investigated. These properties were derived from the microwave scattering parameters measured via the transmission line technique by using a vector network analyzer (VNA) in conjunction with an X band waveguide system. The return loss (RL) values of the samples were obtained from the electromagnetic constitutive parameters (permittivity and permeability). The results indicate that the minimum RL value and the bandwidth change significantly with the amount of ferrite material in the blend. These results encourage further development of MWCNTs blended with ferrite nanoparticles for broadband microwave applications. [ABSTRACT FROM AUTHOR]

In this study, thermoelectric generator (TEG) adaptation in a condensing combi boiler was investigated. The first part of the study comprises experimental analysis, performance tests of a commercially available TEG, and efficiency tests of a condensing combi boiler without TEG adaptation. In the second part of the study, a numerical analysis was carried out to determine the locations of TEGs inside the heat cell. According to the results of the performance tests, approximately 16 V open circuit voltage was generated under 201°C temperature difference. The electrical efficiency of the tested TEG is calculated to be 4.5%. Natural gas was used as fuel in the efficiency tests of the condensing combi boiler and the thermal efficiency was calculated to be 92.3% for 40–60°C water supply and return temperatures. Numerical study showed that the highest temperature difference could be obtained at the upper side of the heat cell with a value of 270°C. The hot side of the TEG module was heated from the inner surface of the heat cell via conduction through the wall, and the water channel was used as the heat sink. Therefore, TEGs were located inside the water channel of the heat cell, with a modification process on the heat cell itself. The performance tests and numerical results show that it is possible to integrate TEGs into the heat cell and decrease the electricity consumption or use combi boilers without an electricity network connection with a properly designed TEG integrated heat cell. [ABSTRACT FROM PUBLISHER]

Abstract: Turbulent natural convection in a vertical parallel plate channel has been investigated both experimentally and numerically. The experimental channel is formed of a uniform temperature heater wall and an opposing glass wall. A fibre flow laser doppler anemometer (LDA) is used to measure velocity profiles along the channel. Simultaneous velocity and temperature profile measurements are made at the channel outlet. A commercial computational fluid dynamics (CFD) code is used to simulate heat transfer and fluid flow in the channel numerically. The code is customised building in some low Reynolds number (LRN) k–ε turbulence models. The numerical method used in this study is found to predict heat transfer and flow rate fairly accurately. It is also capable of capturing velocity and temperature profiles with some accuracy. Experimental and numerical data are presented comparatively in the form of velocity, temperature, and turbulent kinetic energy profiles along the channel for a case. Correlating equations are obtained from the numerical results for heat transfer and induced flow rate and, are presented graphically comparing with other studies available in the literature. [Copyright &y& Elsevier]

Phenol is a neurolytic agent that is widely used by percutaneous retrogasserian injection in the treatment of trigeminal neuralgia. We report a 78-year-old man who had acute unilateral total visual loss after retrogasserian phenol injection for the treatment of trigeminal neuralgia. The patient's visual acuity, eye movements and the pupillary defect did not improve in the affected eye even after mechanical decompression within 30 minutes and medical treatment, neither in the early period nor during the following two months. The visual loss in this patient seems to result from phenol neurotoxicity rather than mechanical compression of the intraorbital optic nerve. This case demonstrates that although percutaneous retrogasserian phenol injection is a relatively safe and noninvasive method of treatment for trigeminal neuralgia, severe complications may occur. [ABSTRACT FROM AUTHOR]

Summary: Objectives: In this study, we investigated the frequency and aetiology of retinal lesions in bacteraemic and septic patients and the risk factors involved. Methods: A total of 150 adult patients in our hospital were included in the study. After consultation with the infectious diseases specialist, the following details were recorded: demographic data, area of admission, underlying diseases, Winston''s clinical condition, Charlson''s co-morbidity index, McCabe''s criteria for underlying disease, APACHE II scoring, community or nosocomial acquisition of bacteraemia, and micro-organism responsible. Blood cultures were obtained from all the patients at least three times. All patients were examined for ocular lesions by the same ophthalmologist 48–72h after the first examination. Some long-term hospitalized patients were evaluated more than once. Results: Patients were divided into six groups: 18 (12%) were bacteraemic non-septic; 31 (20.7%) were septic bacteraemic; 43 (28.7%) were septic non-bacteraemic; 19 (12.7%) had systemic inflammatory response syndrome (SIRS); 16 (10.7%) were non-septic non-bacteraemic but infectious; and 23 (15.3%) were controls. We found bacteraemia-related retinal lesions (BRRLs) in 22/150 (14.7%) of the patients, 19 of whom (86.4%) were in the septic-bacteraemic group while 3 (13.6%) were in the septic non-bacteraemic group. BRRLs were observed in 19/31 (61.3%) patients in the septic-bacteraemic group. Winston and APACHE II scores were found to be higher in patients with BRRLs than in others. BRRLs were more prevalent in septic or bacteraemic patients with central nervous system (CNS) diseases (31.8%) or cancer (27.3%) than in patients with other diseases. The organism most frequently responsible for bacteraemia in patients with BRRLs was Pseudomonas aeruginosa (27.3%), and the second most common was Staphylococcus aureus (22.7%). Conclusion: BRRLs are most frequent in bacteraemic-septic patients (61.3%). The underlying diseases predisposing most to BRRLs are diseases of the CNS and cancers. Ocular examination appears to be a useful aid to diagnosis of bacteraemia or sepsis. [Copyright &y& Elsevier]

Purpose: Leptin is produced primarily by adipose tissue. More recent studies have shown extra sites of leptin production in physiologic and ill human tissues. However, whether leptin originates from human corneas in infectious keratitis and keratoconus is not known. The aim of this study was to demonstrate and quantitate leptin expression in corneas with infectious keratitis and keratoconus and make comparisons to control corneas.Methods: We examined the immunohistochemical staining of leptin in nine corneas surgically excised from patients with infectious keratitis (3 patients), keratoconus (3 patients), and donor corneas (3 patients).Results: The results were analyzed using a semiquantitative scoring system of mild, moderate, and strong. Cells of the infectious keratitis group had the strongest leptin staining intensity, the control group had moderate, and the keratoconus group had mild staining intensity. The more vascular corneas in the infectious keratitis group were also associated with the greatest leptin staining.Conclusions: Our findings indicate that leptin expression was present in all three sources of corneas (infectious keratitis, keratoconus, and normal control). Quantitative scoring would imply it may play a role in infectious keratitis, although further experiments are necessary to establish any causal relationship. [ABSTRACT FROM AUTHOR]

Cortical visual impairment (CVI) most commonly occurs in children after hypoxic insults but may also occur as a sequel of meningitis, encephalitis, head trauma, and hydrocephalus. CVI secondary to hypoglycemia is rarely encountered. A 4-year-old girl was admitted to hospital with a history of bilateral visual impairment. She had several severe hypoglycemic attacks lasting a week in the neonatal period. Bilateral occipital gliotic lesions were defined on magnetic resonance imaging (MR). [ 99m Tc]-hexamethyl propylene amine oxime (HMPAO) brain single-photon emission computerized tomography (SPECT) was performed to determine the cerebral blood flow (CBF). SPECT images showed an extended hypoperfusion area in the right parieto-temporal region with marked non-perfusion areas in bilateral occipital cortices. It should be noted that hypoglycemia has devastating effects on cerebral tissues including optical areas and thus resulting in CVI. We would like to emphasize the importance of early diagnosis and prompt treatment. [ABSTRACT FROM AUTHOR]

The article informs about additional distinct findings in three cases with wolfram syndrome (WS). WS is a rare dysmorphogenetic recessive disorder characterized by early-onset, nonautoimmune diabetes mellitus, progressive optic atrophy and further neurological and endocrinological abnormalities. WS has been attributed to mutations in the WFS1 gene, which codes for a protein predicted to possess 9- 10 transmembrane segments. Wolframin thus appears to be important in the regulation of intracellular Calcium ion homeostasis.