Compact metamaterial-based single/double-negative/near-zero index resonator for 5G sub-6 GHz wireless applications.

The concept, performance, and analyses of distinctive, miniaturized metamaterial (MTM) unit cell addressing the forthcoming Sub 6 GHz 5G applications are presented in this paper. Two circular split-ring resonators (CSRR) with two parallel rectangular copper elements in front of the design and a slotted square element in the background make up the suggested metamaterial. It has a line segment with tunable features that is positioned in the center of the little ring copper structure. The suggested design offers a significant operating frequency band of 220 MHz together with a resonance of transmission coefficient S21 at 3.5 GHz. Furthermore, in two (z & x) principal axes of wave propagation, wide-range achievement, single/double-negative (S/DNG) refractive index, negative permittivity, and near-zero permeability properties were demonstrated. Through varying central slotted-strip line length, resonance frequencies can be selectively altered. Moreover, the metamaterial has overall dimensions of 9 × 9 mm2 and is composed on a Rogers 5880 RT substrate. In order to create the suggested MTM's equivalent circuit, which shows similar coefficient of transmission (S21), a proposed design's numerical simulation is carried out in the CST micro-wave studio. This simulation is after that put to comparison with manufacturing of the design.

Customized Millimeter Wave Channel Model for Enhancement of Next-Generation UAV-Aided Internet of Things Networks.

The success of next-generation Internet of Things (IoT) applications could be boosted with state-of-the-art communication technologies, including the operation of millimeter-wave (mmWave) bands and the implementation of three-dimensional (3D) networks. With some access points (APs) mounted on unmanned aerial vehicles (UAVs), the probability of line-of-sight (LoS) connectivity to IoT nodes could be augmented to address the high path loss at mmWave bands. Nevertheless, system optimization is essential to maintaining reliable communication in 3D IoT networks, particularly in dense urban areas with elevated buildings. This research adopts the implementation of a geometry-based stochastic channel model. The model customizes the standard clustered delay line (CDL) channel profile based on the environmental geometry of the site to obtain realistic performance and optimize system design. Simulation validation is conducted based on the actual maps of highly dense urban areas to demonstrate that the proposed approach is comprehensive. The results reveal that the use of standard channel models in the analysis introduces errors in the channel quality indicator (CQI) that can exceed 50% due to the effect of the environmental geometry on the channel profile. The results also quantify accuracy improvements in the wireless channel and network performance in terms of the CQI and downlink (DL) throughput.

A New Compact Wideband Filter Based on a Coupled Stepped Impedance Resonator.

A new compact wideband filter is introduced to address the requirements of recent communication and radar systems. The filter is based on a quarter-wavelength short-circuit coupled stepped impedance resonator (SIR). The analytical solution shows that the suggested SIR resonator provides a compact size and a wide stopband response, which are essential features in many wireless communication systems. The analytical results also reveal that increasing the impedance ratio of the SIR extends the stopband by increasing the first spurious response and reducing its total length. A compact two-coupled short-circuit SIR filter is designed at 1.23 GHz. The design approach is validated using an ideal transmission line modeling analysis and electromagnetic simulation using CST Microwave Studio 2021. The proposed structure is shown to be flexible, allowing the achievement of a relative bandwidth as low as 5% and as high as 50%. A four-resonator filter is designed by cascading two stages of the designed two-coupled short-circuit SIR filter, which are coupled through a quarter-wavelength line. The simulation results illustrate that the suggested structure can be used to design a filter with any number of resonators. The filter is implemented using a high-resolution LPKF laser machine on Rogers RT/duroid 6010.2LM material with a thickness of 0.635 mm. From the measurements, the bandwidth is found to be 390 MHz and centered at 1325 MHz (29.4% relative bandwidth) and the insertion loss is 1.3 dB. The simulation and experimental results verify the proposed approach and indicate the potential of this component in meeting the design requirements of next-generation microwave circuits related to flexibility and size-compactness.

Design of Hybrid Beamforming System Based on Practical Circuit Parameter of 6-Bit Millimeter-Wave Phase Shifters.

This paper addresses the design of a hybrid beamforming system considering the circuit parameter of six-bit millimeter-wave phase shifters based on the process design kit. The phase shifter design adopts 45 nm CMOS silicon on insulator (SOI) technology at 28-GHz. Various circuit topologies are utilized, and in particular, a design is presented based on switched LC components, connected in a cascode manner. The phase shifter configuration is connected in a cascading manner to get the 6-bit phase controls. Six different phase shifters are obtained, which are 180°, 90°, 45°, 22.5°, 11.25°, and 5.6°, with a minimum number of LC components. The circuit parameters of the designed phase shifters are then incorporated in a simulation model of hybrid beamforming for a multiuser MIMO system. The number of OFDM data symbols used in the simulation is ten for eight users, 16 QAM modulation schemes, -25 dB SNR, 120 simulation runs, and around 170 h runtime. Simulation results are obtained considering four and eight users, assuming accurate technology-based models of RFIC components of the phase shifter as well as ideal phase shifter parameters. The results indicate that the performance of the multiuser MIMO system is affected by the accuracy level of the phase shifter RF component models. The outcomes also reveal the performance tradeoff based on user data streams and the number of BS antennas. By optimizing the amount of parallel data streams per user, higher data transmission rates are achieved, while maintaining acceptable error vector magnitude (EVM) values. In addition, stochastic analysis is conducted to investigate the distribution of the RMS EVM. The outcomes show that the best fitting of RMS EVM distribution of the actual and ideal phase shifters agreed with the log-logistic and logistic distributions, respectively. The obtained (mean, variance) values of the actual phase shifters based on accurate library models are (46.997, 481.36), and for ideal components the values are (36.47, 10.44).

Spinal infections in the north-east of Scotland: a retrospective analysis.

INTRODUCTION: Spinal infection (SI) is uncommon and patients present with varied clinical features. In this review, the presentation, investigation, treatment and outcome of patients with SI in the north-east of Scotland were assessed. METHODS: Electronic medical records of adult patients with SI hospitalised at a health board in the north-east of Scotland between 2014 and 2018 were analysed retrospectively. Collected variables included demographics, presenting clinical features, risk factors, comorbidities, admission blood results, microbiological investigations, imaging, treatment and outcomes. RESULTS: Seventy-two patients were included. Mean age (±sd) was 63.3 years (±14.5). The lumbar spine was the most commonly involved region (51.4%). Back pain (84.7%), altered mobility (33.3%) and fever (29.2%) were the most frequent presenting features. Thoracic spine involvement (p = 0.041), urinary symptoms (p = 0.033), cauda equina syndrome (CES) (p = 0.027) and limb weakness (p = 0.026) were associated with poorer outcome. A better outcome was associated with back pain at presentation (p = 0.03) and underlying malignancy (p = 0.045). Diabetes (15.3%), recent falls (15.3%) and immunosuppression (12.5%) were common. A likely causative organism was found in 54 patients (75.0%) and Staphylococcus aureus was isolated in 41.7% of patients. Penicillins were used in 56.3% of patients and 20.8% underwent surgery. Outcomes were full recovery (38.2%), residual symptoms or neurological deficits (50.0%), paraplegia (4.4%) and death (7.4%). CONCLUSIONS: Poorer outcomes occurred in patients with thoracic disease, limb weakness, urinary symptoms or CES, whereas better outcomes were associated with the presence of back pain on presentation and malignancy. This analysis highlights the diagnostic and therapeutic challenges of SI, alerting clinicians to key factors associated with prognosis.

Knowledge, Attitudes, and Practice towards Occupational Health and Safety among Nursing Students in Gaza Strip, Palestine.

Background: Health and safety in the workplace are critical components in healthcare institutions. Unsafe working conditions are among the causes of poor quality of care and burnout. This study aims to assess the knowledge, attitudes, and practice of occupational health and safety among nursing students at Al-Israa University. Methods: In this cross-sectional study, a structured online questionnaire was distributed from March to May 2021. Of the 350 eligible students, 219 students answered the questionnaire (Response rate=62.6). Data were analyzed using the statistical software IBM-SPSS version 22. Descriptive statistic, Independentsamples T-Test, and ANOVA tests were used. Results: The majority of participants were female (81.7%) and studying in a diploma program. 21% of nursing students have experienced a needle stick injury. The mean scores for knowledge, attitudes, and practice were (M±SD:78.2% ±12.9, M±SD:80.6% ±7.1, and M±SD:81.2% ±7.6) respectively. In terms of knowledge, attitudes, and practice the mean scores were statistically significant between nursing students who attended a safety precautions course and those who didn not (P-value <.05). In terms of attitudes, the mean scores were statistically significant between diploma and bachelor students (P-value =.026). In terms of practice, the means scores were statistically significant between males and females (Pvalue =.017), nursing students who had experience with needle sticks and those who didn't (P-value =.015). Conclusions: The authors recommend that clinical training departments and universities continue to offer occupational health and safety courses and training for health science students. Since the training had a positive impact on the students' practices.

New Compact Antenna Array for MIMO Internet of Things Applications.

A communication system is proposed for the Internet of Things (IoT) applications in desert areas with extended coverage of regional area network requirements. The system implements a developed six-element array that operates at a 2.45 GHz frequency band and is optimized to reduce the size and limit element coupling to less than -20 dB. Analysis of the proposed system involves a multiple-input multiple-output (MIMO) operation to obtain the diversity gain and spectral efficiency. In addition, the radiation efficiency of the proposed antenna is greater than 65% in the operation bandwidth (more than 30 MHz) with a peak of 73% at 2.45 GHz. Moreover, an adaptive beamforming system is presented based on monitoring the direction of arrival (DOA) of various signals using the root MUSIC algorithm and utilizing the DOA data in a minimum variance distortionless response (MVDR) technique beamformer. The developed array is found to have an envelope correlation coefficient (ECC) value of less than 0.013, mean effective gain (MEG) of more than 1 dB, diversity gain of more than 9.9 dB, and channel capacity loss (CCL) of less than 0.4 bits/s/Hz over the operation bandwidth. Adaptive beamforming is used to suppress interference and enhance the signal-to-interference noise ratio (SINR) and is found to achieve a data rate of more than 50 kbps for a coverage distance of up to 100 km with limited power signals.

A potential role for the adrenal gland in autism.

Androgens have been implicated in autism pathophysiology as recently, prenatal exposure to elevated androgens has been proposed as risk factor. However, published data on postnatal sex hormone levels in autistic children are controversial and the source of prenatal androgen exposure in autism remains unknown. Therefore, this study investigated postnatal sex hormone levels and dehydroepiandrosterone (DHEA) to shed light on a potential role for the adrenal gland in autism pathophysiology. A case-control study investigating estradiol (E2), DHEA, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels was conducted with 31 Saudi males with autism and 28 healthy, age-matched boys plasma. Moreover, correlation analysis with measured hormones and previously measured total testosterone (TT) and free testosterone (FT) in the same group of autism was conducted. DHEA was significantly higher (p < 0.05) in the autism group compared to controls. DHEA positively correlated with previously measured TT (r = + 0.79, p < 0.001) and FT (r = + 0.72, p < 0.001) levels in the same autism group. FSH levels were also significantly higher in the autism group than in the control group (p < 0.01). To the best of our knowledge, this is the first study to report a strong positive correlation between TT, FT and DHEA, suggesting an adrenal source for elevated androgen levels.

An in vitro / in vivo release test of risedronate drug loaded nano-bioactive glass composite scaffolds.

Three-dimensional (3D) matrices scaffolds play a noteworthy role in promoting cell generation and propagation. In this study, scaffolds prepared from chitosan/polyvinyl alcohol loaded with/without an osteoporotic drug (risedronate) and nano-bioactive glass (nBG) have been developed to promote healing of bone defects. The scaffolds were characterized by scanning electron microscopy (SEM), porosity test as well as mechanical strength. The pattern of drug release and ability to promote the proliferation of Saos-2osteosarcoma cells had also been reported. Osteogenic potential of the scaffolds was evaluated by testing their effect on healing critical-sized dog's mandibular bone defects. Increasing chitosan and nBG in the porous scaffolds induced decrease in drug release, increased the scaffold's strength and supported their cell proliferation, alkaline phosphatase (ALP) activities, as well as increased calcium deposition. Histological and histomorphometric results demonstrated newly formed bone trabeculae inside critical-sized mandibular defects when treated with scaffolds. Trabecular thickness, bone volume/tissue volume and the percentage of mature collagen fibers increased in groups treated with scaffolds loaded with 10% nBG and risedronate or loaded with 30% nBG with/without risedronate compared with those treated with non-loaded scaffolds and empty control groups. These findings confirmed the potential osteogenic activity of chitosan/polyvinyl alcohol-based scaffolds loaded with risedronate and nBG.

Design of a Compact Dual-Band MIMO Antenna System with High-Diversity Gain Performance in Both Frequency Bands.

A compact four-element dual-band multiple-input and multiple-output (MIMO) antenna system is proposed to achieve high isolation and low channel capacity loss. The MIMO antenna was designed and optimized to cover the dual-frequency bands; the first frequency band is a wide band, and it covers the frequency range of 1550-2650 MHz, while the other frequency band covers the 3350-3650 MHz range. The measured wide-band impedance bandwidths of 1.1 GHz and 300 MHz were achieved in the lower and upper frequency bands, respectively. The proposed structure consists of four novel antenna elements, along with a plus-sign-shaped ground structure on an FR4 substrate. The overall electrical size of the whole dual-band MIMO antenna system is 0.3λ(W) × 0.3λ(L) × 0.008λ(H) for the lower frequency band. It achieved greater than 10 and 19 dB isolation in the lower and upper frequency bands, respectively. The antenna system accomplished an envelope correlation coefficient of |ρ|≤0.08 in the lower frequency band, while it achieved |ρ|≤0.02 in the higher frequency band. The computed channel capacity loss remained less than almost 0.4 bits/s/Hz in both frequency bands. Therefore, it achieved good performance in both frequency bands, with the additional advantage of a compact size. The proposed MIMO antenna is suitable for compact handheld devices and smartphones used for GSM (Global System for Mobiles), UMTS (Universal Mobile Telecommunications Service), WCDMA (Wideband Code Division Multiple Access), LTE (Long Term Evolution), 5G sub-6 GHz, PCS (Personal Communications Service), and WLAN (wireless local area network) applications.

Rapid Magnetic 3D Printing of Cellular Structures with MCF-7 Cell Inks.

A contactless label-free method using a diamagnetophoretic ink to rapidly print three-dimensional (3D) scaffold-free multicellular structures is described. The inks consist of MCF-7 cells that are suspended in a culture medium to which a paramagnetic salt, diethylenetriaminepentaacetic acid gadolinium (III) dihydrogen salt hydrate (Gd-DTPA), is added. When a magnetic field is applied, the host fluid containing the paramagnetic salt is attracted towards regions of high magnetic field gradient, displacing the ink towards regions with a low gradient. Using this method, 3D structures are printed on ultra-low attachment (ULA) surfaces. On a tissue culture treated (TCT) surface, a 3D printed spheroid coexists with a two-dimensional (2D) cell monolayer, where the composite is termed as a 2.5D structure. The 3D structures can be magnetically printed within 6 hours in a medium containing 25 mM Gd-DTPA. The influence of the paramagnetic salt on MCF-7 cell viability, cell morphology, and ability of cells to adhere to each other to stabilize the printed structures on both ULA and TCT surfaces is investigated. Gene expressions of hypoxia-inducible factor 1-alpha (HIF1α) and vascular endothelial growth factor (VEGF) allow comparison of the relative stresses for the printed 3D and 2.5D cell geometries with those for 3D spheroids formed without magnetic assistance. This magnetic printing method can be potentially scaled to a higher throughput to rapidly print cells into 3D heterogeneous cell structures with variable geometries with repeatable dimensions for applications such as tissue engineering and tumour formation for drug discovery.

A new EPR dosimeter based on glutamic acid for radiation processing application.

L-Glutamic acid (L-GA) pellets (3.8 mm × 4 mm) and powder dosimeters were studied in the dose range of 0.1-150 kGy using the electron paramagnetic resonance (EPR) technique. The EPR spectra of irradiated L-GA pellets showed an EPR signal with eight lines, and the intensity of the signal increased with an increase of absorbed dose. The results obtained in terms of the energy-absorption coefficients suggest a similar performance of the L-GA pellets as compared to alanine pellets. The value of the temperature coefficient for the L-GA pellets during irradiation was around - 0.08%/°C which is lower than that reported for alanine dosimeter, 0.14%/°C. The influence of humidity on the pellet response was found to be negligible; i.e., the increase in response was only about 2% for a relative humidity of up to 94%. The response of L-GA powder reached stability 4 h after irradiation and continued to be stable until 47 days after irradiation. In contrast, the response of the L-GA pellet dosimeter reached stability 22 h after irradiation and continued to be stable until 8 days after irradiation. For routine applications, the L-GA pellet dosimeter should be analyzed during the stable period after irradiation, to minimize the uncertainties in dose assessment. The overall two-sigma uncertainties in absorbed dose estimation were 5.1% and 3.9% for the dose ranges of 0.1-15 kGy and 15-150 kGy, respectively. It is concluded that L-GA pellets represent a promising dosimeter material for quantification of radiation doses in food irradiation, medical sterilization and polymer modification.

Pergascript orange-based polymeric solution as a dosimeter for radiotherapy dosimetric validation.

A radiation colour former amino fluoran dye, Pergascript Orange (PGO), in a polyvinyl butyral solution containing a colour developer, hexachloroethane (HCE), was prepared and investigated for radiotherapy dosimetry of 60Co, 6 MV and 15 MV photons. PGO, a colourless dye, reacts with the acid produced upon radiation exposure of HCE, enabling the lactone ring to open and the orange colour of PGO to develop. The ring opening of PGO was confirmed by the appearance of a broad peak of OH- at 3360 cm-1, CO carboxylic peak at 1763 cm-1, and an iminium group peak at 1640 cm-1. The dose response of all prepared compositions was linear in the dose range of 1-20 Gy. Increasing HCE in the dosimeter matrix from 63 mM to 106 mM enhanced the radiation sensitivity by ≈58%. The radiation sensitivity of PGO-PVB (PGO-P) dosimeter is comparable with Fricke gel and higher than N-(Isobutoxymethyl) acrylamide polymer gel dosimeters. The experimental results reveal an energy-independent response (≈1.2% variation at 1σ) in the studied range of radiotherapy beam quality from 60Co beams to the beams from Linacs with a maximum energy of 15 MeV. Based on the theoretical study, this dosimeter is water equivalent from 80 keV to 10 MeV. The overall uncertainty was found to be 4.5% at the 95% confidence level, indicating the possibility of using PGO-P dosimeter in conventional radiotherapy dose verification.

Dosimetric characteristics of a radiochromic polyvinyl butyral film containing 2,4-hexadiyn-1,6-bis(n-butyl urethane).

A radiation-sensitive compound 2,4-hexadiyn-1,6-bis(n-butyl urethane) (HDDBU) was synthesized, characterized by FTIR spectroscopy, and introduced into a thin polyvinyl butyral film to form a radiation dosimeter for industrial irradiation facilities. The monomer polymerizes under gamma radiation, inducing change in the film spectrum in the range of 200-400 nm. According to XRD spectroscopy, the film contains monomeric HDDBU in a non-crystalline state. The dose response function, radiation sensitivity, and dependences of the response on environmental factors were studied. Uncertainty of dose measurements with the proposed dosimetry system was analyzed in detail.

Dosimetric studies for gamma radiation validation of medical devices.

The delivery and validation of a specified dose to medical devices are key concerns to operators of gamma radiation facilities. The objective of the present study was to characterize the industrial gamma radiation facility and map the dose distribution inside the product-loading pattern during the validation and routine control of the sterilization process using radiochromic films. Cardboard phantoms were designed to achieve the homogeneity of absorbed doses. The uncertainty of the dose delivered during validation of the sterilization process was assessed.

EPR dosimetric properties of radiation--formed radicals in arginine monohydrochloride.

Arginine monohydrochloride rods (3×10 mm) were irradiated with (60)Co γ-rays to study radicals for dosimetric materials with Electron Paramagnetic Resonance (EPR). The rods have significant signal which develops upon irradiation and the intensity of signal increases upon the increase in irradiation dose. The rods can be used in the dose range from 5 to 120 KGy. The temperature coefficient was found to equal +0.22% °C(-1). The dose response, influence of humidity and post-irradiation storage at different conditions are discussed. The overall uncertainty for calibration of arginine monohydrochloride rode dosimeters at 2σ was found to be 2.85%.

Origin oriented management of inverted papilloma of the frontal sinus.

BACKGROUND: Despite the great progress in endoscopic management of inverted papilloma (IP), involvement of the frontal sinus (FS) remains a challenge. METHODOLOGY: Six cases of FS IP were assessed. Extent of surgery included simple frontal recess clearance, extended frontal sinusotomy, and modified Lothrop approach. There was no need for adjuvant frontal trephination or an external osteoplastic flap. RESULTS: FS involvement was observed in 6 out of 119 cases of IP (5%). In one case, IP was originating from the FS and in four it was extending to the FS. The sixth case had a wide origin from the anterior ethmoid and FS. Complete resection of FS IP was achieved in all cases with a single incidence of CSF leak. No recurrence was identified after a follow-up period of an average of 27 months. CONCLUSIONS: FS IP originating outside FS can be delivered transnasally with or without frontal ostium widening and preserving FS mucosa and bone. Inverted papillomata originating from FS proper and those with origin from inside and outside the FS can also be resected tranasnasally after widening of the frontal ostium with removal of surrounding mucosa and drilling or curettage of underlying bone at attachment sites.

Biosynthesis of cyclodextrin glucosyltransferase by the free and immobilized cells of Bacillus cereus NRC7 in batch and continuous cultures.

AIMS: The objective of this study was to enhance the production of cyclodextrin glucanotransferase (CGTase) produced by a local isolate Bacillus cereus NRC7. METHODS AND RESULTS: In batch culture, maximal CGTase activity (69·0 U ml(-1)) was reached after 24-h incubation period. In continuous production of CGTase by the free cells of B. cereus NRC7, maximal reactor productivity (11·76 KU l(-1) h(-1)), with enzyme concentration of 49·0 U ml(-1) and specific productivity of 904·6 U per g wet cells per h, was attained at dilution rate of 0·24 h(-1), over a period of 640 h. Bacillus cereus NRC7 cells were immobilized on chitosan. The immobilization conditions with respect to matrix concentration and maximal cell loading were optimized for maximal CGTase production. In repeated batch operation, the activity of the immobilized cells was stable during ten cycles and the activity remained between 51 and 55 U ml(-1). In packed-bed reactor, the immobilized cells showed maximal productivity (27·18 KU l(-1) h(-1)) with enzyme concentration of 54·63 U ml(-1) and specific productivity of 151·89 U per g wet cells per h at dilution rate of 0·5 h(-1). The half-life of the immobilized cells was higher than 20 days. CONCLUSIONS: Continuous fermentation by the immobilized cells in packed-bed reactor is an appropriate potential technique for B. cereus NRC7 CGTase production that gave maximum productivity (27·18 KU l(-1) h(-1)), which was 9·47-, 2·31-, 12·24- and 12·94-fold higher than the free cells in batch, free cells in continuous, immobilized cells in batch and repeated batch cultures, respectively. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study that evaluates CGTase productivity, in different fermentation modes, in terms of specific productivity (U per gram cells per h). In continuous fermentation by immobilized cells, maximal levels of CGTase productivity are higher than the previously reported values.