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Abstract The delivery of kidney care, particularly haemodialysis treatment, can result in substantial environmental impact through greenhouse emissions, natural resources depletion and waste generation. However, strategies exist to mitigate this impact and improve long term environmental sustainability for the provision of haemodialysis treatment. The nephrology community has begun taking actions to improve the environmental sustainability of dialysis, but much work remains to be done by healthcare professionals, dialysis providers and professional organisations.

Presentation of Cushing’s syndrome during pregnancy is extremely rare. We report a 21-year-old female with Cushing’s syndrome diagnosed at 23 weeks of gestation and had recurrent acute pulmonary oedema during the antepartum and postpartum period. She delivered prematurely via emergency caesarean section at 28 weeks of gestation. This case highlights the rare occurrence of recurrent acute pulmonary oedema during pregnancy and consequential premature birth in a patient with adrenal Cushing’s. She was diagnosed with adrenal Cushing’s during the postpartum period based on unsuppressed serum cortisol after overnight and low-dose dexamethasone suppression test with a suppressed ACTH. CT scan of the adrenal glands revealed a right adrenal cortical adenoma. The risk of complications in infants and mothers who suffer from Cushing’s syndrome needs to be handled carefully. The diagnosis of Cushing’s syndrome in pregnant women often overlaps and is difficult to establish in early pregnancy.

Abstract Background Coronavirus Disease 2019 (COVID-19) infection has been associated with a hypercoagulable state with increased reports of thrombotic events. Acute kidney injury requiring dialysis is common in critically ill patients and circuit clotting compromises efficacy of treatment. This study aims to analyze the circuit life and circuit clotting during continuous kidney replacement therapy (CKRT) and intermittent hemodialysis in patients with and without COVID-19. Methods This is a single-center, retrospective cohort study in critically ill patients undergoing CKRT or intermittent hemodialysis between 1 February 2020 to 22 May 2020. Patients in the intensive care unit (ICU) with COVID-19 infection and contemporary controls who tested negative were included. Co-primary outcomes were functional circuit life for patients on CKRT and all circuit clotting events for patients on CKRT and/or intermittent hemodialysis. Results Seventy CKRT circuits and 32 intermittent hemodialysis sessions for 12 COVID-19 cases and 22 CKRT circuits and 18 intermittent hemodialysis sessions for 15 controls were analyzed. CKRT circuit clotting was more common in the COVID-19 group compared to the control group (64% vs 36%, p = 0.02), despite higher anticoagulation use in the COVID-19 group (41% vs 14%, p = 0.02). Functional CKRT circuit life was similar in COVID-19 patients and controls (median 11 vs 12 h, p = 0.69). On Cox regression analysis, circuit clotting was similar with hazard ratio (HR) 1.90 [95% confidence interval (CI): 0.89–4.04]; however, clotting was increased in COVID-19 patients after adjustment for anticoagulation use (HR: 3.31 [95% CI 1.49–7.33]). In patients with COVID-19, CKRT circuits with anticoagulation had a longer circuit life compared to CKRT circuits without anticoagulation (median 22 versus 7 h respectively, p

Objectives Primary healthcare internationally is facing a workforce crisis with fewer junior doctors choosing general practice (GP) as a career. In the UK, a national report on GP careers highlighted adverse influences during medical school on students’ career choices. The authors explored these influences in two urban UK medical schools, both with relatively low numbers of students entering GP training.Design Using a phenomenological approach, the authors thematically analysed the reflective diaries of four medical students who were recruited as ‘participant researchers’ over a period of 10 months. These students made regular reflexive notes about their experiences related to GP career perceptions in their academic and personal environments, aiming to capture both positive and negative perceptions of GP careers. The research team discussed emerging data and iteratively explored and developed themes.Setting Two UK medical schoolsParticipants Undergraduate medical studentsResults Seven key themes were identified: the lack of visibility and physicality of GP work, the lack of aspirational GP role models, students’ perceptions of a GP career as default, the performativity of student career choice with the perceptions of success linked to specialism, societal perceptions of GP careers, gender stereotyping of career choices and the student perception of life as a GP.Conclusions Students overwhelmingly reflected on negative cues to GP careers, particularly through their experience of the hidden curriculum. Three recommendations are made: the need for increased representation of GP role models in clinical curricula content delivery and senior leadership; ensuring GP clerkships involve an active and authentic student role with patients, enabling students to experience GP’s ‘work’ including managing complexity, uncertainty and risk. Finally, institutions need to consider students’ experiences of the hidden curriculum and the effect this can have on students’ perception of careers, alongside the challenges of rankings and perceived hierarchical positioning of disciplines.

The Ras/Raf/MEK/ERK and PI3K/Akt/mTOR signaling pathways are essential for cancer cell survival. Here, the authors describes a molecule a131 with dual-inhibitory properties, which targets PI5P4K and mitosis, and it is involved in Ras/Raf/MEK/ERK and PI3K/Akt/mTOR crosstalk, thereby causing reversible growth arrest in normal cells and cell death of tumor cells.

OptiMusic training uses a unique audio-visual system to utilize a combination of lights and sound to train children with special needs to explore and interact with the environment. The training encourages children to create music and sound effects by sweeping a bat across the light beams. It is an enjoyable way for children with behavior challenges and learning difficulties to engage with their surroundings. It can be used to teach concepts, cause and effect, communication, social skills, teamwork, fine-gross motor skills (particularly hand-eye coordination), musical timing and rhythm, audio-visual memory, and aural sequencing. It is very flexible and can be tailored to the needs and different levels of children with special needs. OptiMusic training for children with special needs uses a variety of music, sounds and images to create a powerful, multi-sensory and learning environment for these children. In this article, we would like to share our experiences and learnings gained throughout the development of the OptiMusic programme for children with special needs. There is an introduction to the system; structure and curriculum; and creative ideas and activities in the programme.

The inclusion of animals in therapeutic activities, known as animal-assisted therapy, can be used as a treatment practice for people with autism spectrum disorder (ASD). Reported outcomes included improvements in multiple areas of functioning, such as the physical, social, emotional, and/or cognitive functioning of the child, as well as providing educational and motivational effectiveness for children with autism. Animal assisted therapy, in this case dog assisted therapy, involves a dog with specific characteristics becoming part of a child’s therapy. Three cases are narrated on the effect of dog assisted therapy on children with autism. This leads to the conclusion that animal assisted therapy helps children with autism learn to trust, de-stress, care for another living creature, step out of their comfort zones to try something new, and communicate.

Background/objective: One thousand liver transplantations have been performed at the only liver transplant center in Hong Kong over a period of 22 years, which covered the formative period of living donor liver transplantation. These 1000 transplantations, which marked the journey of liver transplantation from development to maturation at the center, should be educational. This research was to study the experience and to reflect on the importance of technical innovations and case selection. Methods: The first 1000 liver transplantations were studied. Key technical innovations and surgical therapeutics were described. Recipient survival including hospital mortality was analyzed. Recipient survival comparison was made for deceased donor liver transplantation and living donor liver transplantation indicated by hepatocellular carcinoma and other diseases. Results: Among the 1000 transplantations, 418 used deceased donor grafts and 582 used living donor grafts. With the accumulation of experience, hospital mortality improved to < 2% in the past 2 years. In the treatment of diseases other than hepatocellular carcinoma, living donor liver transplantation was superior to deceased donor liver transplantation, with a 10-year recipient survival around 90%. Conclusion: Transplant outcomes have been improving consistently over the series, with a very low hospital mortality and a predictably high long-term survival.

Children with autism often show a wide range of difficulties in sensory processing where they might experience over or under sensitivity to sound, touch, taste, smell and light. There is a need to provide appropriate sensory stimulation or comfort to help children with autism to integrate their senses and have more pleasurable interactions with people and their environment. Snoezelen® is a multisensory environment that provides a range of sensory stimulations that are tailored to meet the needs of children with autism. The multisensory environment provides direct and indirect stimulation of sensory modalities and can be used individually or collectively to provide sensory training. The purpose of this study was to experiment with the use of equipment in the multisensory program, as an intervention approach to provide appropriate sensory stimulation or comfort in a sensory environment that addresses the sensory processing needs of children with autism. The study focused on three main sensory areas - visual, auditory and tactile. The study comprised of six children with autism from ages 5-8 years old. Each autistic child attended an hour session twice a month over a year (24 sessions). The findings show that children with autism improve in their visual, auditory and tactile sensory functioning, using a structured program. The children learn to follow instructions, understand specific concepts, and became more aware of their surroundings.

The suitable size of a graft is a key element in the success of liver transplantation. A small-for-size liver graft is very likely to sustain a significant degree of injury as a result of ischemia, preservation, reperfusion, and rejection. Usually, small-for-size grafts are a concern in living-donor liver transplantation rather than in deceased-donor liver transplantation. Here, we describe the successful transplantation of a liver from a 2-year-old deceased donor to a 61-year-old male recipient who suffered from liver failure related to hepatitis B. No report of successful deceased-donor liver transplantation with discrepancies between donor and recipient age and size to such an extent has been found in the literature. Despite unusually large discrepancies, with effort in minimizing the ischemic time, revised surgical techniques, and strong regenerative power of the “young” graft, the old patient's liver function gradually returned to normal. This again proves that the definition of a “suitable graft” evolves with time and experience.

Individual with autism usually appear physically normal but display motor and coordination deficit. Therefore, they need fine motor, gross motor and motor coordination skills training. A structured Music and Movement Therapy for individual with autism was developed and for the purpose of this study, the focus is to review the effect of the Music and Movement Therapy on motor and coordination skills of persons with autism. A total of 41 children and adolescents participated in the study and were divided into two groups. Group 1 comprised of 18 children (5 girls and 13 boys). The age of these children ranged from 2 to 10 years old. Meanwhile, Group 2 comprised of 23 adolescents (2 girls and 21 boys). The age of these adolescents ranged from 11 to 22 years old. A session of the Music and Movement Therapy was carried out weekly and two sets of Music and Movement Therapy module were used alternately for 10 months. Each Music and Movement Therapy session is for 45 minutes. A Motor and Coordination Performance Checklist was developed to enable the parents, facilitators and research assistant to evaluate the participants’ skills averagely once a month for 10 months. T-test and descriptive analyses were conducted to examine any significant improvement and changes of the motor and coordination skills among the two groups. In this study, the children and adolescents with autism showed improvement in their motor and coordination skills after participating through the Music and Movement Therapy in this study.

Background/Objective: Donor right hepatectomy (DRH) was developed by master liver surgeons and has been applied in many liver transplant centers as the mainstay for adult living donor liver transplantation. It is a major and complex surgical operation performed on living liver donors for the benefit of liver recipients. The donors deserve the lowest though inevitable morbidity and mortality. In this study, the surgical outcomes of DRH performed by newer surgeons at an established center were studied to assess the transferability of the techniques of this standardized procedure. Methods: We studied 450 consecutive DRHs performed by 11 surgeons. Three surgeons initiated and developed the transplant program and performed the first 200 DRHs (Era I). The role of chief surgeon in the following 250 DRHs (Era II) was gradually taken up by four newer surgeons with close guidance initially. Results: Blood loss and operation time at the end of Era I versus the beginning of Era II were 251 vs. 341 mL and 391 vs. 497 minutes. The learning curve effect in Era I did not occur in Era II. The complication rates of the last 50 cases in Era I and Era II were 16% and 24%, respectively. Era I had one donor death whereas Era II had no donor death. Conclusion: At an established center, DRH can be carried out safely by newer surgeons with good outcomes.

Autism is a severe neurological disorder that is characterized by “severe and pervasive impairment in several areas of development”, especially the development in the perception and modulation of sensory information. The prevalence of autism has risen to 1 in 88 births in recent years (Autism Society of America, 2012). Studies show that early intervention and training are the most effective way to help children with autism to cope and eventually become independent. School teachers, parents, or caregivers often face difficulty in communicating with these children because it is hard to understand their thinking and behaviour, especially with those children that have little or no verbal communication. Thus, understanding the thought pattern of an autistic child would be useful for the teachers, parents and caregivers to effectively intervene and redirect the thinking and manage his or her behaviour. The purpose of this study is to use an audio-visual cognitive aid as an intervention tool to understand and help children with autism. An audio-visual cognitive aid was developed and has five themes, (a) colour, (b) light, (c) visual, (d) perception, (e) cartoon, and (f) character. The audio-visual cognitive presentation was shown to 24 children with autism (from very low functioning group to high functioning group) aged between 5-10 years old. Each child attended a 45 minutes session three times weekly over six months. After the children had seen the audio-visual presentation, they were asked to draw and describe what they had seen. Their drawings or descriptions were analyzed for their thinking pattern and conclusions drawn which form the basis for behavioural management. The study showed that the children with autism who participated in this study responded positively to the computer based audio-visual cognitive aid. For very low and low functioning children, this audio-visual cognitive aid has helped to activate their responses to audio and visual stimuli, increase their attention span, responsiveness, concentration, and their cooperative ability. On the other hand, the audio-visual cognitive aid has helped moderate and high functioning children to maintain attention, understand and connect with their environment. This study supports previous studies that computer based programme is an effective tool to understand the thought pattern of autistic children and modify their thinking and behaviour.

Liver transplantation is a standard treatment for patients with familial amyloidotic polyneuropathy (FAP) with disease progression. Given the multiorgan involvement by amyloidosis, the heart is often involved. When poor cardiac function becomes prohibitive to liver transplantation, a combined heart-liver transplantation (CHLT) is the only realistic treatment. This article records a CHLT for a patient with FAP whose removed liver was immediately transplanted as an amyloidotic hepatic allograft (AHA) to a patient having hepatocellular carcinoma and cirrhosis in a sequential liver transplantation. In the CHLT, the heart and liver are donated by a deceased donor. The newly implanted heart did not tolerate cross clamping of the inferior vena cava (IVC), so a side-to-side anastomosis was performed to connect the IVC and that of the liver graft. Therefore, the AHA was devoid of an IVC. The infrarenal cava procured from the deceased donor was used for reconstruction of the AHA to match a whole graft used in routine deceased-donor liver transplantation. Venoplasty was performed using the graft right hepatic vein and the middle and left hepatic vein stump to form a single cuff. The reconstructed AHA was implanted to the recipient conveniently like a usual whole graft.

Music therapy is an emerging approach to teach a variety of skills to children with special needs. Music therapy is a non-threatening and enjoyable way for these children, who struggle with both expressive and receptive communication, to find a way to express themselves so as to be understood by others. It is also used to train motor coordination, behavior and functional academic skills. Research was conducted in Malaysia which shows that music therapy is an effective medium in training children with autism and a program was developed. The music therapy protocol is proposed and can be used by anyone with no formal music training.

OBJECTIVE: To develop a simple tool for assessing the severity of disability resulting from Japanese encephalitis and whether, as a result, a child is likely to be dependent. METHODS: A new outcome score based on a 15-item questionnaire was developed after a literature review, examination of current assessment tools, discussion with experts and a pilot study. The score was used to evaluate 100 children in Malaysia (56 Japanese encephalitis patients, 2 patients with encephalitis of unknown etiology and 42 controls) and 95 in India (36 Japanese encephalitis patients, 41 patients with encephalitis of unknown etiology and 18 controls). Inter- and intra-observer variability in the outcome score was determined and the score was compared with full clinical assessment. FINDINGS: There was good inter-observer agreement on using the new score to identify likely dependency (K = 0.942 for Malaysian children; K = 0.786 for Indian children) and good intra-observer agreement (K = 1.000 and 0.902, respectively). In addition, agreement between the new score and clinical assessment was also good (K = 0.906 and 0.762, respectively). The sensitivity and specificity of the new score for identifying children likely to be dependent were 100% and 98.4% in Malaysia and 100% and 93.8% in India. Positive and negative predictive values were 84.2% and 100% in Malaysia and 65.6% and 100% in India. CONCLUSION: The new tool for assessing disability in children after Japanese encephalitis was simple to use and scores correlated well with clinical assessment.

Liver transplantation is a life-saving treatment modality, but is hindered by the scarcity of deceased-donor liver grafts. To acquire more liver grafts and thus save more lives, various techniques have been devised and policies adopted, including living-donor, split-graft and sequential liver transplantation; extended donor criteria; and donation after cardiac death. However, with these techniques and policies come a range of entailed medical concerns and concomitant ethical dilemmas, mainly bearing on the welfare of donors and potential donors. In this article, we provide an overview of how the transplant community works towards the end of extending the liver donor pool, with the aim of ensuring that more liver transplant candidates receive their transplant as early as possible. The current strategies in Hong Kong in this regard are also reviewed.

Background and aimSpontaneous rupture of hepatocellular carcinoma (HCC) carries a high mortality. The use of radiofrequency ablation (RFA) in recent years has enriched the armamentarium for hemostasis of spontaneously ruptured HCCs but its results have not been documented. This study investigated the prognosis and outcome of spontaneous rupture of HCC as well as the results of using RFA for hemostasis.Patients and methodFrom January 1991 to December 2010, 5283 patients were diagnosed with HCC at our hospital, and 189 of them had spontaneous rupture of HCCs. They were grouped under two periods: period 1, 1991-2000, n = 70; period 2, 2001-2010, n = 119. RFA was available in period 2 only.ResultsHepatitis B virus infection was predominant in both periods. Surgical hemostasis was mainly achieved by hepatic artery ligation in period 1 and by RFA in period 2. The 30-day hospital mortality after surgical treatment was 55.6% (n = 18) in period 1 and 19.2% (n = 26) in period 2 (p = 0.012). Multivariate analysis identified 4 independent factors for better overall survival, namely, hemostasis by transarterial embolization [corrected] (hazard ratio 0.516, 95% confidence interval 0.354-0.751), hemostasis by RFA (hazard ratio 0.431, 95% confidence interval 0.236-0.790), having surgery as a subsequent treatment (hazard ratio 0.305, 95% confidence interval 0.186-0.498), and a serum total bilirubin level ConclusionThe use of RFA for hemostasis during laparotomy greatly reduced the hospital mortality rate when compared with conventional hepatic artery ligation.

Background. Liver is the commonest site for metastasis in patients with neuroendocrine tumour (NET). A vast majority of treatment strategies including liver directed nonsurgical therapy, liver directed surgical therapy, and nonliver directed therapy have been proposed. In this study we aim to investigate the outcome of liver resection in neuroendocrine tumour liver metastases (NELM). Method. 293 patients had hepatectomy for liver metastasis in our hospital between June 1996 and December 2010. Twelve patients were diagnosed to have NET in their final pathology and their data were reviewed. Results. The median ages of the patients were 48.5 years (range 20–71 years). Eight of the patients received major hepatectomy. Four patients received minor hepatectomy. The median operation time was 418 minutes (range 195–660 minutes). The median tumor size was 8.75 cm (range 0.9–21 cm). There was no hospital mortality. The overall one-year and three-year survivals were 91.7% and 55.6%. The one-year and three-year disease-free survivals were 33.3% and 16.7%. Conclusion. Hepatectomy is an effective and safe treatment for NELM. Reasonable outcome on long term overall survival and disease-free survival can be achieved in this group of patients with a low morbidity rate.

The study underscores the urgent need for sustainable waste management by focusing on circular economy principles, government regulations, and public awareness to combat ecological threats, pollution, and climate change effects. It explores extracting nanocellulose from waste streams such as textile, paper, agricultural matter, wood, animal, and food waste, providing a detailed process framework. The emphasis is on waste-derived nanocellulose as a promising material for eco-friendly products. The research evaluates the primary mechanical and thermal properties of nanocellulose from various waste sources. For instance, cotton-derived nanocellulose has a modulus of 2.04-2.71 GPa, making it flexible for lightweight applications. Most waste-derived nanocelluloses have densities between 1550 and 1650 kg/m 3 , offering strong, lightweight packaging support while enhancing biodegradability and moisture control. Crystallinity influences material usage: high crystallinity is ideal for packaging (e.g., softwood, hardwood), while low crystallinity suits textiles (e.g., cotton, bamboo). Nanocelluloses exhibit excellent thermal stability above 200 °C, useful for flame-retardant coatings, insulation, and polymer reinforcement. The research provides a comprehensive guide for selecting nanocellulose materials, highlighting their potential across industries like packaging, biomedical, textiles, apparel, and electronics, promoting sustainable innovation and a more eco-conscious future., Competing Interests: Declaration of competing interest We declare that we wish to confirm the absence of any known conflicts of interest associated with this publication. Additionally, we affirm that there has been no significant financial support for this work that could have influenced its outcome. We confirm that the authors have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

In the design of phase shifters, the modeling equations are too complicated and require some approximations to be derived correctly by hand. In response to this problem, this paper presents a generalized concept, algorithm, and MATLAB code that provide the exact modeling equations of the transmission parameters and the scattering parameters of any 90° wideband stub-loaded phase shifter. The proposed code gives the modeling equations in term of variables for any number of stubs and characteristic impedance value by utilizing the symbol-based analysis of the MATLAB code. It also illustrates the results as a function of normalized frequency relative to the center frequency f o , and can be and can be tailored to any user-defined frequency range. As a matter of comparison, a three-stub wideband 90° stub-loaded phase shifter is simulated using CST Microwave Studio and experimentally fabricated on Rogers RT5880 dielectric substrate with dimensions of 30 × 40 × 0.8 mm 3 . The comparison reveals the accuracy of the proposed computerized modeling with -10 dB impedance bandwidth equal to 90% (0.55 f o -1.45 f o ), (90°∓5°) phase difference bandwidth equal to 100% (0.5 f o -1.5 f o ), and negligible insertion loss. The novelty of this work is that the proposed code provides the exact modeling equations of the stub-loaded phase shifter for any number of stubs regardless the complexity of the mathematical derivations.

In this paper, a radiating element consisting of a modified circular patch is proposed for MIMO arrays for 5G millimeter-wave applications. The radiating elements in the proposed 2 × 2 MIMO antenna array are orthogonally configured relative to each other to mitigate mutual coupling that would otherwise degrade the performance of the MIMO system. The MIMO array was fabricated on Rogers RT/Duroid high-frequency substrate with a dielectric constant of 2.2, a thickness of 0.8 mm, and a loss tangent of 0.0009. The individual antenna in the array has a measured impedance bandwidth of 1.6 GHz from 27.25 to 28.85 GHz for S 11 ≤ -10 dB, and the MIMO array has a gain of 7.2 dBi at 28 GHz with inter radiator isolation greater than 26 dB. The gain of the MIMO array was increased by introducing frequency-selective surface (FSS) consisting of 7 × 7 array of unit cells comprising rectangular C-shaped resonators, with one embedded inside the other with a central crisscross slotted patch. With the FSS, the gain of the MIMO array increased to 8.6 dBi at 28 GHz. The radiation from the array is directional and perpendicular to the plain of the MIMO array. Owing to the low coupling between the radiating elements in the MIMO array, its Envelope Correlation Coefficient (ECC) is less than 0.002, and its diversity gain (DG) is better than 9.99 dB in the 5G operating band centered at 28 GHz between 26.5 GHz and 29.5 GHz.

This paper introduces a multi-input multiple-output (MIMO) antenna array system that provides improved radiation diversity for multi-standard/multi-mode 5G communications. The introduced MIMO design contains four pairs of miniaturized self-complementary antennas (SCAs) fed by pairs of independently coupled structures which are symmetrically located at the edge corners of the smartphone mainboard with an overall size of 75 × 150 (mm 2 ). Hence, in total, the design incorporates four pairs of horizontally and vertically polarized resonators. The elements have compact profiles and resonate at 3.6 GHz, the main candidate bands of the sub-6 GHz 5G spectrum. In addition, despite the absence of decoupling structures, adjacent elements demonstrate high isolation. To the best of the authors' knowledge, it is the first type of smartphone antenna design using dual-polarized self-complementary antennas that could possess anti-interference and diversity properties. In addition to exhibiting desirable radiation coverage, the presented smartphone antenna also supports dual polarizations on different sides of the printed circuit board (PCB). It also exhibits good isolation, high-gain patterns, improved radiation coverage, low ECC/TARC, and sufficient channel capacity. The introduced antenna design was manufactured on a standard smartphone board and its main characteristics were experimentally measured. Simulations and measurement results are generally in good agreement with each other. Moreover, the presented antenna system delivers low SAR with adequate efficiency when it comes to the appearance of the user. Hence, the design could be adapted to 5G hand-portable devices. As an additional feature, a new ultra-compact phased array millimeter-wave antenna with super-wide bandwidth and end-fire radiation is being introduced for integration into the MIMO antenna systems. As a result, the proposed antenna system design with improved radiation and multi-standard operation is a good candidate for future multi-mode 5G cellular applications., (© 2023. The Author(s).)

In this paper, a high-performance antenna-on-chip (AoC) is implemented on gallium arsenide (GaAs) wafer based on the substrate integrated waveguide (SIW) and metasurface (MTS) technologies for terahertz band applications. The proposed antenna is constructed using five stacked layers comprising metal-GaAs-metal-GaAs-metal. The conductive electromagnetic radiators are implemented on the upper side of the top GaAs layer, which has a metallic ground-plane at its underside. The metallic feedline is implemented at the underside of the bottom GaAs layer. Dual wrench-shaped radiators are framed by metallic vias connected to the ground-plane to create SIW cavity. This technique mitigates the surface waves and the substrate losses, thereby improving the antenna's radiation characteristics. The antenna is excited by a T-shaped feedline implemented on the underside of the bottom GaAs substrate layer. Electromagnetic (EM) energy from the feedline is coupled to the radiating elements through the circular and linear slots etched in the middle ground-plane layer. To mitigate the surface-wave interactions and the substrate losses in the bottom GaAs layer, the feedline is contained inside a SIW cavity. To enhance the antenna's performance, the radiators are transformed into a metamaterial-inspired surface (i.e., metasurface), by engraving periodic arrangement of circular slots of sub-wavelength diameter and periodicity. Essentially, the slots act as resonant scatterers, which control the EM response of the surface. The antenna of dimensions of 400 × 400 × 8 μm 3 is demonstrated to operate over a wide frequency range from 0.445 to 0.470 THz having a bandwidth of 25 GHz with an average return-loss of - 27 dB. The measured average gain and radiation efficiency are 4.6 dBi and 74%, respectively. These results make the proposed antenna suitable for AoC terahertz applications., (© 2023. The Author(s).)

This paper focuses on designing a dual-band, bandpass filter configuration inspired by glide-symmetric structures in a single plane. Geometry configuration of elliptical slots on both sides of single substrate generally affects electromagnetic fields as well as rejection bands. Easy fabrication with misalignment avoidance during assembly procedure unlike conventional structures based on gap waveguide technology, make them appropriate to use in electromagnetic devices. Parametric study on dispersion characteristics is carried out in this article to find out how rejection-bands are offered through breaking the symmetry. A method for producing symmetry is also suggested, which may be helpful for reconfigurable devices. Moreover, equivalent circuit model is demonstrated to get insight of the mechanism of the presented glide symmetry scheme. The transmission frequency ranges of two passbands with center frequencies of 19.74 GHz and 28.233 GHz are shown by the measured and calculated S- parameters of five unit-cell structures., Competing Interests: The authors declare no competing financial interests., (© 2022 The Authors.)

An innovative off-chip antenna (OCA) is presented that exhibits high gain and efficiency performance at the terahertz (THz) band and has a wide operational bandwidth. The proposed OCA is implemented on stacked silicon layers and consists of an open circuit meandering line. It is shown that by loading the antenna with an array of subwavelength circular dielectric slots and terminating it with a metamaterial unit cell, its impedance bandwidth is enhanced by a factor of two and its gain on average by about 4 dB. Unlike conventional antennas, where the energy is dissipated in a resistive load, the technique proposed here significantly reduces losses. The antenna is excited from underneath the antenna by coupling RF energy from an open-circuited feedline through a slot in the ground-plane of the middle substrate layer. The feedline is shielded with another substrate layer which has a ground-plane on its opposite surface to mitigate the influence of the structure on which the antenna is mounted. The antenna has the dimensions 12.3 × 4.5 × 0.905 mm 3 and operates across the 0.137-0.158 THz band corresponding to a fractional bandwidth of 14.23%. Over this frequency range the average measured gain and efficiency are 8.6 dBi and 77%, respectively. These characteristics makes the proposed antenna suitable for integration in sub-terahertz near-field electronic systems such as radio frequency identification (RFID) devices with high spatial resolution., (© 2022. The Author(s).)

Millimetre-wave frequencies are promising for sensitive detection of glucose levels in the blood, where the temperature effect is insignificant. All these features provide the feasibility of continuous, portable, and accurate monitoring of glucose levels. This paper presents a metamaterial-inspired resonator comprising five split-rings to detect glucose levels at 24.9 GHz. The plexiglass case containing blood is modelled on the sensor's surface and the structure is simulated for the glucose levels in blood from 50 mg/dl to 120 mg/dl. The novelty of the sensor is demonstrated by the capability to sense the normal glucose levels at millimetre-wave frequencies. The dielectric characteristics of the blood are modelled by using the Debye parameters. The proposed design can detect small changes in the dielectric properties of blood caused by varying glucose levels. The variation in the transmission coefficient for each glucose level tested in this study is determined by the quality factor and resonant frequency. The sensor presented can detect the change in the quality factor of transmission response up to 2.71/mg/dl. The sensor's performance has also been tested to detect diabetic hyperosmolar syndrome. The sensor showed a linear shift in resonant frequency with the change in glucose levels, and an R2 of 0.9976 was obtained by applying regression analysis. Thus, the sensor can be used to monitor glucose in a normal range as well as at extreme levels., Competing Interests: The authors have declared that no competing interests exist.

A novel technique is shown to improve the isolation between radiators in antenna arrays. The proposed technique suppresses the surface-wave propagation and reduces substrate loss thereby enhancing the overall performance of the array. This is achieved without affecting the antenna's footprint. The proposed approach is demonstrated on a four-element array for 5G MIMO applications. Each radiating element in the array is constituted from a 3 × 3 matrix of interconnected resonant elements. The technique involves (1) incorporating matching stubs within the resonant elements, (2) framing each of the four-radiating elements inside a dot-wall, and (3) defecting the ground plane with dielectric slots that are aligned under the dot-walls. Results show that with the proposed approach the impedance bandwidth of the array is increased by 58.82% and the improvement in the average isolation between antennas #1&2, #1&3, #1&4 are 8 dB, 14 dB, 16 dB, and 13 dB, respectively. Moreover, improvement in the antenna gain is 4.2% and the total radiation efficiency is 23.53%. These results confirm the efficacy of the technique. The agreement between the simulated and measured results is excellent. Furthermore, the manufacture of the antenna array using the proposed approach is relatively straightforward and cost effective., (© 2022. The Author(s).)

In this paper, single-element and MIMO microstrip antenna with two pairs of unequal slits is proposed as a circularly polarized antenna with negligible back radiation for 5G mid-band handsets. The unequal pairs of slits are engraved on the antenna patch to guarantee the presence of the circular polarization (CP). The proximity-coupled feeding technique is used to excite the proposed microstrip antenna in order to provide larger antenna -10 dB bandwidth which approaches 10.8% (3.48-3.87 GHz). A novel analysis technique is proposed in this paper that demonstrates the 3D axial ratio pattern in order to generate CP in the broadside direction without affecting the structure of the ground plane which ensures weak back radiation. The 3 dB axial ratio bandwidth (ARBW) is found to be equal to 4.1% extended along the range (3.58-3.73 GHz). To make the design more compatible with the 5G mid-band handsets, the 2 × 2 MIMO structure of the proposed antenna with reduced mutual coupling (less than -20 dB) is also presented in this work. The simulation and measured results are in good agreement, and both verify the CP characteristics and the weak back radiation of the proposed antenna.

An offset quad-element, two-port, high-gain, and multiband multiple-input multiple-output (MIMO) planar antenna based on a log-periodic dipole array (LPDA) for Ku/K-band wireless communications is proposed, in this paper. A single element antenna has been designed starting from Carrel's theory and then optimized with a 50-Ω microstrip feed-line with two orthogonal branches that results mainly in a broadside radiation pattern and improves diversity parameters. For experimental confirmation, the designed structure is printed on an RT-5880 substrate with a thickness of 1.57 mm. The total substrate dimensions of the MIMO antenna are 55 × 45 mm 2 . According to the measured results, the designed structure is capable of working at 1.3% (12.82-12.98 GHz), 3.1% (13.54-13.96 GHz), 2.3% (14.81-15.15 GHz), 4.5% (17.7-18.52 GHz), and 4.6% (21.1-22.1 GHz) frequency bands. Additionally, the proposed MIMO antenna attains a peak gain of 4.2-10.7 dBi with maximum element isolation of 23.5 dB, without the use of any decoupling structure. Furthermore, the analysis of MIMO performance metrics such as the envelope correlation coefficient (ECC) and mean effective gain (MEG) validates good characteristics, and field correlation performance over the operating band. The proposed design is an appropriate option for multiband MIMO applications for various wireless systems in Ku/K-bands., (© 2022. The Author(s).)

Matching the antenna's impedance to the RF-front-end of a wireless communications system is challenging as the impedance varies with its surround environment. Autonomously matching the antenna to the RF-front-end is therefore essential to optimize power transfer and thereby maintain the antenna's radiation efficiency. This paper presents a theoretical technique for automatically tuning an LC impedance matching network that compensates antenna mismatch presented to the RF-front-end. The proposed technique converges to a matching point without the need of complex mathematical modelling of the system comprising of non-linear control elements. Digital circuitry is used to implement the required matching circuit. Reliable convergence is achieved within the tuning range of the LC-network using control-loops that can independently control the LC impedance. An algorithm based on the proposed technique was used to verify its effectiveness with various antenna loads. Mismatch error of the technique is less than 0.2%. The technique enables speedy convergence (< 5 µs) and is highly accurate for autonomous adaptive antenna matching networks.

This paper presents the results of a study on developing an effective technique to increase the performance characteristics of antenna arrays for sub-THz integrated circuit applications. This is essential to compensate the limited power available from sub-THz sources. Although conventional array structures can provide a solution to enhance the radiation-gain performance however in the case of small-sized array structures the radiation properties can be adversely affected by mutual coupling that exists between the radiating elements. It is demonstrated here the effectiveness of using SIW technology to suppress surface wave propagations and near field mutual coupling effects. Prototype of 2 × 3 antenna arrays were designed and constructed on a polyimide dielectric substrate with thickness of 125 μm for operation across 0.19-0.20 THz. The dimensions of the array were 20 × 13.5 × 0.125 mm 3 . Metallization of the antenna was coated with 500 nm layer of Graphene. With the proposed technique the isolation between the radiating elements was improved on average by 22.5 dB compared to a reference array antenna with no SIW isolation. The performance of the array was enhanced by transforming the patch to exhibit metamaterial characteristics. This was achieved by embedding the patch antennas in the array with sub-wavelength slots. Compared to the reference array the metamaterial inspired structure exhibits improvement in isolation, radiation gain and efficiency on average by 28 dB, 6.3 dBi, and 34%, respectively. These results show the viability of proposed approach in developing antenna arrays for application in sub-THz integrated circuits.

The paper demonstrates an effective technique to significantly enhance the bandwidth and radiation gain of an otherwise narrowband composite right/left-handed transmission-line (CRLH-TL) antenna using a non-Foster impedance matching circuit (NF-IMC) without affecting the antenna's stability. This is achieved by using the negative reactance of the NF-IMC to counteract the input capacitance of the antenna. Series capacitance of the CRLH-TL unit-cell is created by etching a dielectric spiral slot inside a rectangular microstrip patch that is grounded through a spiraled microstrip inductance. The overall size of the antenna, including the NF-IMC at its lowest operating frequency is 0.335λ 0  × 0.137λ 0  × 0.003λ 0 , where λ 0 is the free-space wavelength at 1.4 GHz. The performance of the antenna was verified through actual measurements. The stable bandwidth of the antenna for |S 11 |≤ - 18 dB is greater than 1 GHz (1.4-2.45 GHz), which is significantly wider than the CRLH-TL antenna without the proposed impedance matching circuit. In addition, with the proposed technique the measured radiation gain and efficiency of the antenna are increased on average by 3.2 dBi and 31.5% over the operating frequency band.

A compact fabric antenna structure integrated with electromagnetic bandgap structures (EBGs) covering the desired frequency spectrum between 2.36 GHz and 2.40 GHz for Medical Body-Area Networks (MBANs), is introduced. The needs of flexible system applications, the antenna is preferably low-profile, compact, directive, and robust to the human body's loading effect have to be satisfied. The EBGs are attractive solutions for such requirements and provide efficient performance. In contrast to earlier documented EBG backed antenna designs, the proposed EBG behaved as shielding from the antenna to the human body, reduced the size, and acted as a radiator. The EBGs reduce the frequency detuning due to the human body and decrease the back radiation, improving the antenna efficiency. The proposed antenna system has an overall dimension of 46×46×2.4 mm3. The computed and experimental results achieved a gain of 7.2 dBi, a Front to Back Ratio (FBR) of 12.2 dB, and an efficiency of 74.8%, respectively. The Specific Absorption Rate (SAR) demonstrates a reduction of more than 95% compared to the antenna without EBGs. Moreover, the antenna performance robustness to human body loading and bending is also studied experimentally. Hence, the integrated antenna-EBG is a suitable candidate for many wearable applications, including healthcare devices and related applications., Competing Interests: The authors have declared that no competing interests exist.

Combined sewer overflow structures (CSO) play an important role in sewer networks. When the local capacity of a sewer system is exceeded during intense rainfall events, they act as a "safety valve" and discharge excess rainfall run-off and wastewater directly to a natural receiving water body, thus preventing widespread urban flooding. There is a regulatory requirement that solids in CSO spills must be small and their amount strictly controlled. Therefore, a vast majority of CSOs in the UK contain screens. This paper presents the results of a feasibility study of using low-cost, low-energy acoustic sensors to remotely assess the condition of CSO screens to move to cost-effective reactive maintenance visits. In situ trials were carried out in several CSOs to evaluate the performance of the acoustic sensor under realistic screen and flow conditions. The results demonstrate that the system is robust within ±2.5% to work successfully in a live CSO environment. The observed changes in the screen condition resulted in 8-39% changes in the values of the coefficient in the proposed acoustic model. These changes are detectable and consistent with observed screen and hydraulic data. This study suggested that acoustic-based sensing can effectively monitor the CSO screen blockage conditions and hence reduce the risk of non-compliant CSO spills.

Analogue-to-digital converters (ADC) using oversampling technology and the Σ-∆ modulation mechanism are widely applied in digital audio systems. This paper presents an audio modulator with high accuracy and low power consumption by using a discrete second-order feedforward structure. A 5-bit successive approximation register (SAR) quantizer is integrated into the chip, which reduces the number of comparators and the power consumption of the quantizer compared with flash ADC-type quantizers. An analogue passive adder is used to sum the input signals and it is embedded in a SAR ADC composed of a capacitor array and a dynamic comparator which has no static power consumption. To validate the design concept, the designed modulator is developed in a 180 nm CMOS process. The peak signal to noise distortion ratio (SNDR) is calculated as 106 dB and the total power consumption of the chip is recorded as 3.654 mW at the chip supply voltage of 1.8 V. The input sine wave of 0 to 25 kHz is sampled at a sampling frequency of 3.2 Ms/s. Moreover, the results achieve a 16-bit effective number of bits (ENOB) when the amplitude of the input signal is varied between 0.15 and 1.65 V. By comparing with other modulators which were realized by a 180 nm CMOS process, the proposed architecture outperforms with lower power consumption.

In this paper an automatic adaptive antenna impedance tuning algorithm is presented that is based on quantum inspired genetic optimization technique. The proposed automatic quantum genetic algorithm (AQGA) is used to find the optimum solution for a low-pass passive T-impedance matching LC-network inserted between an RF transceiver and its antenna. Results of the AQGA tuning method are presented for applications across 1.4 to 5 GHz (satellite services, LTE networks, radar systems, and WiFi bands). Compared to existing genetic algorithm-based tuning techniques the proposed algorithm converges much faster to provide a solution. At 1.4, 2.3, 3.4, 4.0, and 5.0 GHz bands the proposed AQGA is on average 75%, 49.2%, 64.9%, 54.7%, and 52.5% faster than conventional genetic algorithms, respectively. The results reveal the proposed AQGA is feasible for real-time application in RF-front-end systems.

A feasibility study is presented on the performance parameters of a novel on-chip antenna based on metasurface technology at terahertz band. The proposed metasurface on-chip antenna is constructed on an electrically thin high-permittivity gallium arsenide (GaAs) substrate layer. Metasurface is implemented by engraving slot-lines on an array of 11 × 11 circular patches fabricated on the top layer of the GaAs substrate and metallic via-holes implemented in the central patch of each row constituting the array, which connects the patch to the leaky-wave open-ended feeding slot-lines running underneath the patches. The slot-lines are connected to each other with a slit. A waveguide port is used to excite the array via slot-lines that couple the electromagnetic energy to the patches. The metasurface on-chip antenna is shown to exhibit an average measured gain in excess of 10 dBi and radiation efficiency above 60% over a wide frequency range from 0.41 to 0.47 THz, which is significant development over other on-chip antenna techniques reported to date. Dimensions of the antenna are 8.6 × 8.6 × 0.0503 mm 3 . The results show that the proposed GaAs-based metasurface on-chip antenna is viable for applications in terahertz integrated circuits.

This paper presents a novel on-chip antenna using standard CMOS-technology based on metasurface implemented on two-layers polyimide substrates with a thickness of 500 μm. The aluminium ground-plane with thickness of 3 μm is sandwiched between the two-layers. Concentric dielectric-rings are etched in the ground-plane under the radiation patches implemented on the top-layer. The radiation patches comprise concentric metal-rings that are arranged in a 3 × 3 matrix. The antennas are excited by coupling electromagnetic energy through the gaps of the concentric dielectric-rings in the ground-plane using a microstrip feedline created on the bottom polyimide-layer. The open-ended feedline is split in three-branches that are aligned under the radiation elements to couple the maximum energy. In this structure, the concentric metal-rings essentially act as series left-handed capacitances C L that extend the effective aperture area of the antenna without affecting its dimensions, and the concentric dielectric rings etched in the ground-plane act as shunt left-handed inductors L L , which suppress the surface-waves and reduce the substrates losses that leads to improved bandwidth and radiation properties. The overall structure behaves like a metasurface that is shown to exhibit a very large bandwidth of 0.350-0.385 THz with an average radiation gain and efficiency of 8.15dBi and 65.71%, respectively. It has dimensions of 6 × 6 × 1 mm 3 that makes it suitable for on-chip implementation.

The internal insulation condition of capacitor voltage transformers (CVTs) is a key influence factor that affects their measurement performance and safe operation. However, the internal insulation would age along with long-time operation and degrade due to environmental factors, and once the insulation degradation grows, serious damage and even explosion may happen in CVTs; hence, it is necessary to monitor the internal insulation condition of CVTs, and the fault type and fault degree need to be identified. In this paper, a data-driven internal insulation condition identification method for CVTs is proposed. Both the amplitude and phase of the output voltage of CVTs are collected, and then, recognition models based on the combination of the output voltages and distribution topology of CVTs in substations are built. A possibilistic fuzzy clustering method is used to monitor the internal insulation condition of CVTs, and different types and different degrees of insulation faults could be identified effectively. Finally, the proposed method is verified in several cases; not only the preset typical faults in the method could be identified effectively but also the faults beyond the preset faults could be diagnosed.