In this paper, a dual-core photonic crystal fiber (DC-PCF) based surface plasmon resonance (SPR) bio-compatible sensor is proposed for various bio-organic molecules and biochemical analytes ...refractive index (RI) detection in the visible to near-infrared region (0.5 to <inline-formula> <tex-math notation="LaTeX">2~\mu \text{m} </tex-math></inline-formula>). Two hexagonal ring lattice with all circular air-holes are used to simplify the sensor structure. To make the practical applications feasible, plasmonic material and analyte sensing layer both are employed at the outer surface of the fiber. Noble plasmonic material gold (Au) having a thickness of 30 nm is used to excite the surface plasmons. A thin layer of titanium oxide (TiO 2 ) having a thickness of 5 nm is also considered as an adhesive layer between the Au and silica glass. The sensor response is investigated using the mode solver based finite element method (FEM). Numerical results indicate that the proposed sensor shows a maximum amplitude sensitivity (AS) of 6829 RIU<inline-formula> <tex-math notation="LaTeX">^{-1} </tex-math></inline-formula>, amplitude resolution (AR) of <inline-formula> <tex-math notation="LaTeX">5\times 10 ^{-6} </tex-math></inline-formula> RIU, maximum wavelength sensitivity (WS) of 28,000 nm/RIU, and wavelength resolution (WR) of <inline-formula> <tex-math notation="LaTeX">3.57\times 10 ^{-6} </tex-math></inline-formula> RIU, using the amplitude and wavelength interrogation methods, respectively. Moreover, a maximum figure of merit (FOM) of 2800 RIU<inline-formula> <tex-math notation="LaTeX">^{-1} </tex-math></inline-formula> is obtained, which is the highest among the reported PCF-SPR sensor. Owing to the promising sensitivity and simple structure, the proposed sensor can be potentially applicable for the detection of biochemical solutions and biological samples.
A wider range of refractive index (RI) detecting D-shaped photonic crystal fiber (PCF)-based surface plasmon resonance (SPR) sensor is proposed in this paper for the RI detection of analyte ranging ...from 1.18 to 1.36. To make the proposed sensor practically implementable, analyte sensing layer and chemically stable gold (Au) as a plasmonic material layer for SPR are placed outside the D-shaped PCF structure as a part of simple detection technique. Using the finite-element method with a circular perfectly matched boundary layer, it is shown through simulations that the proposed D-shaped PCF-based SPR sensor offers maximum wavelength interrogation sensitivity of 20000 nm/RIU (refractive index unit) and maximum amplitude interrogation sensitivity of 1054 RIU -1 . In addition, the proposed sensor shows maximum wavelength interrogation resolutions of 5 × 10 -6 RIU and amplitude interrogation resolutions of 16.7 × 10 -6 RIU. Due to high wavelength and amplitude sensitivity over wider range of analyte RI and improved sensing resolutions, this proposed sensor can be implemented for the detection of biological analytes, organic chemicals, bio-molecules, and other analytes.
In this paper, a low-loss, spiral lattice photonic crystal fiber (PCF)-based plasmonic biosensor is proposed for its application in detecting various biomolecules (i.e., sugar, protein, DNA, and ...mRNA) and biochemicals (i.e., serum and urine). Plasmonic material gold (Au) is employed externally to efficiently generate surface plasmon resonance (SPR) in the outer surface of the PCF. A thin layer of titanium oxide (TiO
) is also introduced, which assists in adhering the Au layer to the silica fiber. The sensing performance is investigated using a mode solver based on the finite element method (FEM). Simulation results show a maximum wavelength sensitivity of 23,000 nm/RIU for a bio-samples refractive index (RI) detection range of 1.32-1.40. This sensor also exhibits a very low confinement loss of 0.22 and 2.87 dB/cm for the analyte at 1.32 and 1.40 RI, respectively. Because of the ultra-low propagation loss, the proposed sensor can be fabricated within several centimeters, which reduces the complexity related to splicing, and so on.
This article proposes a hybrid array antenna where a cavity-backed antenna is used jointly with a patch antenna using half-mode substrate integrated waveguide technology (HMSIW) to reduce antenna ...size. This hybrid structure consists of a flexible Rogers RO4003C substrate (<inline-formula> <tex-math notation="LaTeX">\epsilon_{{r}} =3.55 </tex-math></inline-formula>) showing linearly polarized TE101 mode where the cross-polarization level (XPL) is less than −12 dBi. An inset feed has been utilized to excite the main cavity resonator, and later by proximity coupling, the parasitic patch is also excited in TE101 mode. By further dividing the outer patch, four new cases of antenna have emerged, and comprehensive investigations on their parameters based on simulation have been presented. It paints an upgrade of the antenna's performance. As per simulations, further dividing of the patch helps to bring out positive changes in the antenna's performance by escalating gain, bandwidth (BW), and efficiencies while also lessening XPL, sidelobe levels (SLLs), and associated loss up to a satisfying level. The proposed antenna is then fabricated and experimentally validated in its theoretical analysis. A couple of experimentally validated parameters make this fabricated sample suitable for wireless application and maintain good agreement with numerical simulation. CST Microwave Studio and HFSS carried out the associated numerical simulation.
Participating in physical exercise is advantageous for maintaining optimum health, improving physical capacity, decreasing the likelihood of chronic diseases, and promoting overall wellbeing. This ...study aimed to find out the prevalence and factors that contribute to musculoskeletal injuries among individuals who participated in fitness activities at the gym. This cross-sectional study included 1123 gym members, both male and female, aged between 18 and 50 years, from selected fitness centers in Bangladesh. Musculoskeletal injuries were assessed using the Nordic musculoskeletal disorder questionnaire. Binary logistic regression identified the gym members' predictors of musculoskeletal injuries. The highest prevalence of musculoskeletal injuries at the low back (36.6%) was seen among the eight body sites, followed by the shoulder (24.7%) and knee (17.1%). Males (aOR 2.589, CI 1.18 to 5.65) and those who go to the gym to lose weight (aOR 3.859, CI 0.91 to 16.33) and for physical fitness (aOR 1.895, CI 1.07 to 3.35) had a greater risk of musculoskeletal injury. Participants who carried out strength training exercises (aOR 4.10, CI 2.74 to 6.19) had a four-fold increased risk of musculoskeletal injuries than those who did not. Furthermore, higher adjusted odds of musculoskeletal injuries were found for the potential causes of injuries in incorrect holding (aOR 1.69, CI 1.10 to 2.60), overweight lifting (aOR 2.00, CI 1.30 to 3.08), lack of workout knowledge (aOR 3.56, CI 2.09 to 5.85), and insufficient information from the trainer (aOR 5.66, CI 1.84 to 17.39). Musculoskeletal injuries are highly prevalent among gym-goers in Bangladesh. The back was the most often injured area, followed by the shoulder and knee. It is important to exhibit caution and take extra care while doing strength training activities in order to avoid injury. Prior to engaging in gym-based activities, it is essential to have a thorough understanding of proper exercise knowledge.
A highly sensitive surface plasmon resonance (SPR) sensor on a dual-core photonic crystal fiber (PCF) for low refractive index (RI) detection is presented in this paper. Plasmonic material silver ...(Ag) is deposited outside of the fiber structure to detect changes of the surrounding medium's refractive index. To prevent oxidation a thin layer of titanium dioxide (TiO 2 ) is employed on top of the silver. The sensor shows maximum wavelength sensitivity and amplitude sensitivity of 116,000 nm/RIU and 2452 RIU −1 with corresponding resolutions (R) of 8.62 × 10 −7 and 5.55 × 10 −6 RIU, respectively. A thorough study of the relevant literature yielded that these attained sensitivities in both interrogation methods are the highest among reported PCF-SPR sensors to date. In addition, the sensor possesses a very high figure of merit of 2320 in the sensing range of 1.29 to 1.39. Therefore, it would be a suitable candidate for pharmaceutical inspection, organic chemical sensing, and biosensing and other analytes detection.
The SARS‐CoV‐2 coronavirus is responsible for the current COVID‐19 pandemic, with an ongoing toll of over 5 million infections and 333 thousand deaths worldwide within the first 5 months. Insight ...into the phylodynamics and mutation variants of this virus is vital to understanding the nature of its spread in different climate conditions. The incidence rate of COVID‐19 is increasing at an alarming pace within subtropical South‐East Asian nations with high temperatures and humidity. To understand this spread, we analysed 444 genome sequences of SARS‐CoV‐2 available on the GISAID platform from six South‐East Asian countries. Multiple sequence alignments and maximum‐likelihood phylogenetic analyses were performed to analyse and characterize the non‐synonymous (NS) mutant variants circulating in this region. Global mutation distribution analysis showed that the majority of the mutations found in this region are also prevalent in Europe and North America, and the concurrent presence of these mutations at a high frequency in other countries indicates possible transmission routes. Unique spike protein and non‐structural protein mutations were observed circulating within confined area of a given country. We divided the circulating viral strains into four major groups and three subgroups on the basis of the most frequent NS mutations. Strains with a unique set of four co‐evolving mutations were found to be circulating at a high frequency within India, specifically. Group 2 strains characterized by two co‐evolving NS mutants which alter in RdRp (P323L) and spike (S) protein (D614G) were found to be common in Europe and North America. These European and North American variants have rapidly emerged as dominant strains within South‐East Asia, increasing from a 0% prevalence in January to an 81% by May 2020. These variants may have an evolutionary advantage over their ancestral types and could present a large threat to South‐East Asia for the coming winter.
BackgroundThe objective of this study was to identify the prevalence of long COVID symptoms in a large cohort of people living with and affected by long COVID and identify any potential associated ...risk factors.MethodsA prospective survey was undertaken of an inception cohort of confirmed people living with and affected by long COVID (aged 18–87 years). 14392 participants were recruited from 24 testing facilities across Bangladesh between June and November 2020. All participants had a previously confirmed positive COVID-19 diagnosis, and reported persistent symptoms and difficulties in performing daily activities. Participants who consented were contacted by face-to-face interview, and were interviewed regarding long COVID, and restriction of activities of daily living using post COVID-19 functional status scale. Cardiorespiratory parameters measured at rest (heart rate, systolic blood pressure, diastolic blood pressure, oxygen saturation levels, maximal oxygen consumption, inspiratory and expiratory lung volume) were also measured.ResultsAmong 2198 participants, the prevalence of long COVID symptoms at 12 weeks was 16.1%. Overall, eight long COVID symptoms were identified and in descending order of prominence are: fatigue, pain, dyspnoea, cough, anosmia, appetite loss, headache and chest pain. People living with and affected by long COVID experienced between 1 and 8 long COVID symptoms with an overall duration period of 21.8±5.2 weeks. Structural equation modelling predicted the length of long COVID to be related to younger age, female gender, rural residence, prior functional limitation and smoking.ConclusionIn this cohort, at 31 weeks post diagnosis, the prevalence of long COVID symptoms was 16.1%. The risk factors identified for presence and longer length of long COVID symptoms warrant further research and consideration to support public health initiatives.
In this paper, an extremely sensitive Photonic Crystal Fiber (PCF) based Surface Plasmon Resonance (SPR) sensor having D-shaped structure has been proposed. Gold has been used as the plasmonic ...material, and it has been coated outside of the fiber on its glassy surface to detect the change in the refractive index of the surrounding medium. Gold has been chosen as it is chemically stable and has no impact on the surrounding aqueous medium. Maximum Wavelength Sensitivity (WS) of 216,000 nm/RIU and Amplitude Sensitivity (AS) of 1680 RIU −1 have been achieved for the analyte refractive index range 1.23 to 1.42 by the proposed sensor. After conducting a detailed literature review in the relevant field, it has been revealed that the proposed sensor possesses the highest wavelength sensitivity among recently reported PCF-SPR sensors to this date. The proposed sensor also exhibits a resolution of 4.63 × 10 −7 RIU and FOM of 1200. Consequently, the proposed sensor can become an ideal candidate in the field of biomedical sensing, chemical sensing, and other lower RI analytes sensing.
In this work, a highly sensitive dual-core configured microchannel-based plasmonic refractive index (RI) sensor was investigated, which can be used for low RI detection. Both the sensing layer and ...the plasmonic material layer were built outside of the fiber design to detect the surrounding medium’s RI changes. Additionally, the effects of different plasmonic materials gold (Au), silver (Ag), and copper (Cu) toward sensitivity were investigated for the same structure. An adhesive agent was used in this work, titanium dioxide (TiO2), and was coated on top of the plasmonic material to prevent the oxidation of Ag and Cu. The coupling strength between the fundamental mode and the surface plasmon polariton (SPP) mode was observed to be very strong due to the TiO2 adhesive agent. With a resolution of 7.41 × 10−7 RIU, maximum wavelength sensitivity (WS) of 135,000 nm/RIU and amplitude sensitivity (AS) of 3239 RIU−1 were achieved using the proposed sensor while using Au as a plasmonic material for an analyte RI range of 1.29–1.39. A detailed study of relevant literature revealed that the achieved wavelength sensitivity for plasmonic material gold (Au) is the highest among reported photonic crystal fiber (PCF)-surface plasmon resonance (SPR) sensors to date.
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