Electrically Tunable Two-Color Cholesteric Laser.

Two-color lasing emission from an asymmetric structure, consisting of two dye-doped cholesteric liquid crystal (DD-CLC) layers separated by a transparent interlayer, is demonstrated. The DD-CLC mixtures have different reflection bands with long-wavelength band edges located at the green and red wavelengths of the visible spectrum, respectively. For the laser action, the CLC hosts provide the feedback, and the fluorescent laser dyes represent the active medium. When the stacked structure is optically pumped above the threshold, two simultaneous laser lines separated by 123 nm are observed at the long-wavelength band edges of the DD-CLC mixtures. The influence of an electric field on lasing behavior is also analyzed and discussed in terms of the reflection spectrum and laser action. The results show a reversible tuning of the reflection band, accompanied by a modification of the lasing characteristics under the application of an external field. Above a specific threshold voltage, one of the emission lines is suppressed and the other is conserved. With a further increase in the voltage, both laser emissions are entirely inhibited. The investigated structure demonstrates a simple technique to obtain an electrically tunable multi-wavelength laser, which might pave the way for a new generation of organic laser sources.

Dual-Wavelength Lasing with Orthogonal Circular Polarizations Generated in a Single Layer of a Polymer-Cholesteric Liquid Crystal Superstructure.

We investigate the laser emission from a polymer-cholesteric liquid crystal superstructure with coexisting opposite chiralities fabricated by refilling a right-handed polymeric scaffold with a left-handed cholesteric liquid crystalline material. The superstructure exhibits two photonic band gaps corresponding to the right- and left-circularly polarized light. By adding a suitable dye, dual-wavelength lasing with orthogonal circular polarizations is realized in this single-layer structure. The wavelength of the left-circularly polarized laser emission is thermally tunable, while the wavelength of the right-circularly polarized emission is relatively stable. Due to its relative simplicity and tunability characteristics, our design might have broad application prospects in various fields of photonics and display technology.

Early Diagnosis of Coronary Artery Disease by Inflammatory Biomarkers of Atherosclerosis in Patients with Angina.

Early diagnosis of coronary artery disease (CAD) in patients with chest pain is a challenge. Currently diagnosis of CAD is confirmed by coronary angiography, which is invasive and not easily available in developing countries. Therefore, it is imperative to establish noninvasive biomarker for early diagnosis of CAD in patients with angina and determine the diagnostic accuracy of inflammatory biomarkers of atherosclerosis in comparison to angiography and correlate with severity of CAD in patients with angina. Diagnostic accuracy study was carried out in tertiary care hospitals, Rawalpindi, Pakistan. Total of 58 patients aged 55.24 ± 11.61 years, with chest pain and troponin-I -ve, having coronary artery stenosis ≥50% were included as cases of CAD and 55 subjects having stenosis <50% were included as controls. Nuclear factor kappa-B (NF-κB), tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and high-sensitivity C-reactive protein (hs-CRP) were analyzed on immunoassay analyzers. The receiver operating characteristic curve analysis revealed significant (P < 0.05) high area under curve (95% confidence interval) with sensitivity and specificity of NF-κB 0.76 (0.65-0.85), 73% and 65%; TNF-α 0.72 (0.61-0.81), 71% and 69%; IL-6 0.62 (0.52-0.71), 64% and 53% and hs-CRP 0.62 (0.52-0.71), and 53% and 56% in CAD patients compared to controls. There was significant positive correlation between NF-κB (r = 0.44), TNF-α (r = 0.37), IL-6 (r = 0.23), and hs-CRP (r = 0.23) with severity of CAD by Gensini score. The inflammatory biomarkers, especially NF-κB and TNF-α, have highest diagnostic accuracy and indicate severity of atherosclerosis in patients with angina. These markers may be used as noninvasive biomarkers to exclude healthy individuals before undergoing angiography.

Plasmon-induced transparency in a reconfigurable composite valley photonic crystal.

We propose a new kind of reconfigurable topological valley photonic crystal (TVPC), and a novel topological waveguide can be formed by constructing a domain wall between two TVPCs with opposite valley-Chern indices. The topological waveguide mode in the composite TVPC has large group refractive index. A topologically protected coupled waveguide cavity system is then designed by introducing a hexagonal ring cavity at the center of the straight domain wall of a combined TVPC, in which a narrow plasmon induced transparency window rises at 3.8848 GHz with a Q-factor of 1387 and a maximum group refractive index as high as 186. We propose a notch filter with a resonant frequency of 3.8852 GHz and a very high Q-factor of 10224. By changing the refractive index of liquid crystals via an external voltage applied between two parallel metal plates, the filter can be switched between band-pass and band-stop based on the reconfigurable topological interface state.

Presenting Characteristics, Comorbidities, and Outcomes Among Patients With COVID-19 Hospitalized in Pakistan: Retrospective Observational Study.

BACKGROUND: COVID-19 became a pandemic rapidly after its emergence in December 2019. It belongs to the coronavirus family of viruses, which have struck a few times before in history. Data based on previous research regarding etiology and epidemiology of other viruses from this family helped played a vital role in formulating prevention and precaution strategies during the initial stages of this pandemic. Data related to COVID-19 in Pakistan were not initially documented on a large scale. In addition, due to a weak health care system and low economic conditions, Pakistan's population, in general, already suffers from many comorbidities, which can severely affect the outcome of patients infected with COVID-19. OBJECTIVE: COVID-19 infections are coupled with a manifestation of various notable outcomes that can be documented and characterized clinically. The aim of this study was to examine these clinical manifestations, which can serve as indicators for early detection as well as severity prognosis for COVID-19 infections, especially in high-risk groups. METHODS: A retrospective observational study involving abstraction of demographic features, presenting symptoms, and adverse clinical outcomes for 1812 patients with COVID-19 was conducted. Patients were admitted to the four major hospitals in the Rawalpindi-Islamabad region of Pakistan, and the study was conducted from February to August 2020. Multivariate regression analysis was carried out to identify significant indicators of COVID-19 severity, intensive care unit (ICU) admission, ventilator aid, and mortality. The study not only relates COVID-19 infection with comorbidities, but also examines other related factors, such as age and gender. RESULTS: This study identified fever (1592/1812, 87.9%), cough (1433/1812, 79.1%), and shortness of breath (998/1812, 55.1%) at the time of hospital admission as the most prevalent symptoms for patients with COVID-19. These symptoms were common but not conclusive of the outcome of infection. Out of 1812 patients, 24.4% (n=443) required ICU admission and 21.5% (n=390) required ventilator aid at some point of disease progression during their stay at the hospital; 25.9% (n=469) of the patients died. Further analysis revealed the relationship of the presented symptoms and comorbidities with the progression of disease severity in these patients. Older adult patients with comorbidities, such as hypertension, diabetes, chronic kidney disease, and asthma, were significantly affected in higher proportions, resulting in requirement of ICU admission and ventilator aid in some cases and, in many cases, even mortality. CONCLUSIONS: Older adult patients with comorbidities, such as hypertension, diabetes, asthma, chronic obstructive pulmonary disorder, and chronic kidney disease, are at increased risk of developing severe COVID-19 infections, with an increased likelihood of adverse clinical outcomes.

Delayed admissions and efficacy of steroid use in patients with critical and severe COVID-19: an apprehensive approach.

BACKGROUND: Inadvertent delays in access to appropriate therapeutic interventions in high-risk group coronavirus disease 2019 (COVID-19) patients contribute to mortality in patients with severe/critical disease presentation. OBJECTIVES: The aim of this study was to determine the effect of timely admission to the hospital on mortality of patients with severe/critical COVID-19. Another secondary aspect of this study was to observe the efficacy of time-dependent use of corticosteroids on mortality of critical/severe COVID-19 patients. METHODS: Clinical data of 659 patients with severe/critical COVID-19, admitted to four major tertiary care hospitals from the Islamabad-Rawalpindi region of Pakistan was retrospectively collected from a period February-August 2020. Multivariate logistic regression analysis was carried out to determine the predictors of mortality in severe/critical COVID-19 patients. RESULTS: Out of a total of 659 patients, 469 (71.2%) patients died. Age > 60 years, presence of hypertension, heart disease and kidney disease along with late admission (>5 days) were significant predictors of mortality in patients with severe/critical COVID-19. CONCLUSIONS: The study highlights the importance of well-timed provision of appropriate medical interventions control COVID-19-associated mortality.

Multifunctional and tunable trigate graphene metamaterial with "Lakes of Wada" topology.

Many plasmon-induced transparency (PIT) metamaterials previously reported had limited functions. Their tunabilities were realized by complex discrete structures, which greatly increased the difficulty and cost of device fabrication and adversely affected their resonance characteristics. It is an open question to adjust the Fermi levels of many graphene patterns with only a few in-plane electrodes. We propose and numerically study a novel electrically tunable and multifunctional trigate graphene metamaterial (TGGM) based on the concept of "Lakes of Wada". Benefiting from the trigate regulation, our proposed TGGM turns out to exhibit excellent characteristics, that can not only be used for terahertz band-stop filter, terahertz refractive index sensor, near-field optical switch, slow-light device, but also for double PIT window metamaterial with broad transparency windows and large tunable frequency range.

Use of gastrografin in the management of worm-induced small bowel obstruction in children.

OBJECTIVE: Ascaris-induced small bowel obstruction (SBO) is a common sequel of Ascaris lumbricoides (AL) infestation. Most cases respond to conservative treatment practiced in different centers worldwide. We conceived a prospective randomized trial to compare the conservative treatment with gastrografin administered in addition to the conservative treatment. STUDY DESIGN: This prospective randomized study was conducted between January 2011 and June 2014 at Department of Paediatric and Neonatal Surgery, a tertiary-care hospital. Patients were divided into two groups, one group received conservative treatment and the other received gastrografin in addition to conservative treatment. Forty patients having uncomplicated AL-induced SBO were included in each group. Gastrografin was administered through nasogastric tube and serial clinical and radiological monitoring was performed. The duration of hospital stay, time between admission and first oral feed, passage of worms/flatus were compared in the two groups. Student's t test was used for comparing these variables. RESULTS: Average time for passage of flatus or worms and resolution of abdominal signs and was shorter in gastrografin group as compared to the conservative group. This difference was found to be statistically significant. The average duration of hospital stay in gastrografin group was 25.20 ± 8.01 h whereas it was 61.12 ± 14.64 h in the conservative group (P < 0.001). The difference in the operation rate was statistically insignificant (2 in gastrografin group and 3 in the conservative group).No serious adverse reaction was noted after gastrografin administration. CONCLUSION: Use of gastrografin resulted in faster relief of signs and symptoms of AL-induced SBO, early passage of worms/flatus and return to oral feeds. However, the role of gastrografin role in reducing the likelihood of laparotomy remains inconclusive. Adverse effects of gastrografin can be prevented if it is used in well-hydrated patients.