Towards 76-81 GHz Scalable Phase Shifting by Folded Dual-strip Shielded Coplanar Waveguide with Liquid Crystals

2021 ◽  
Vol 5 (4) ◽  
pp. 14-22
Author(s):  
Jinfeng Li
Keyword(s):  
Liquid Crystals ◽  
Phased Array ◽  
Coplanar Waveguide ◽  
Phase Shifters ◽  
Phase Shifting ◽  
The Novel ◽  
Loss Reduction ◽  
Proof Of Concept ◽  
Tunable Dielectrics

Unconventional folded shielded coplanar waveguide (FS-CPW) has yet to be fully investigated for tunable dielectrics-based applications. This work formulates designs of FS-CPW based on liquid crystals (LC) for electrically controlled 0-360˚ phase shifters, featuring a minimally redundant approach for reducing the LC volume and hence the costs for mass production. The design exhibits a few conceptual features that make it stand apart from others, noteworthy, the dual-strip structure with a simplified enclosure engraved that enables LC volume sharing between adjacent core lines. Insertion loss reduction by 0.77 dB and LC volume reduction by 1.62% per device are reported at 77 GHz, as compared with those of the conventional single-strip configuration. Based on the proof-of-concept results obtained for the novel dual-strip FS-CPW proposed, this work provides a springboard for follow-up investible propositions that will underpin the development of a phased array demonstrator.

Design and Characterization of Novel Millimeter-Wave MEMS CPW Transmission Lines

2011 ◽  
Vol 204-210 ◽  
pp. 577-582
Author(s):  
Jian Ming Huang ◽  
Y. L. Zhou ◽  
H. Guo
Keyword(s):  
Transmission Lines ◽  
Microelectromechanical Systems ◽  
Coplanar Waveguide ◽  
Characteristic Impedance ◽  
Effective Permittivity ◽  
Phase Shifters ◽  
Mapping Technique ◽  
60 Ghz ◽  
Loss Reduction ◽  
Propagation Properties

The design and development of novel microelectromechanical systems’ (MEMS) coplanar waveguide (CPW) transmission lines, using microshield and groove, are presented in the paper to operate between 5–60 GHz. The quasi-static capacitances of CPW are calculated using the conformal mapping technique to express the propagation properties, i.e., the characteristic impedance and effective permittivity. Simulation results have shown a considerable loss reduction to levels that compare favorably with the conventional CPW. These transmission lines can be widely used in the development of phase shifters, filters, and antennas, because of their advantages in loss reduction and improvement in the performance.

scholarly journals Rethinking Figure-of-Merits of Liquid Crystals Shielded Coplanar Waveguide Phase Shifters at 60 GHz

J ◽  
2021 ◽  
Vol 4 (3) ◽  
pp. 444-451 ◽  
Author(s):  
Jinfeng Li
Keyword(s):  
Liquid Crystals ◽  
Insertion Loss ◽  
Phase Shifter ◽  
Coplanar Waveguide ◽  
Volume Ratio ◽  
Phase Shifters ◽  
60 Ghz ◽  
Two Phase ◽  
Differential Phase Shift ◽  
Millimetre Wave

The demand for reconfigurable millimetre-wave (mm-Wave) components based on highly anisotropic liquid crystals (LC) is higher than ever before for the UK and worldwide. In this work, 60 GHz investigation on a bespoke shielded coplanar waveguide (SCPW) phase shifter structure filled with 16 types of microwave-enabled nematic LCs respectively indicates that the patterns of the device’s figure-of-merit (FoM, defined as the ratio of maximum differential phase shift to maximum insertion loss) reshuffle from those of the characterised LC materials’ FoM (defined as the ratio of tunability to maximum dissipation factor). To be more specific, GT7-29001- and MDA-03-2838-based phase shifters exhibit the highest FoM for devices, outperforming phase shifters based on GT5-28004 and TUD-566 with the highest FoM for materials. Such a mismatch between the device’s FoM and LC’s FoM implies a nonlinearly perturbed wave-occupied volume ratio effect. Furthermore, the relationship between insertion loss and the effective delay line length is nonlinear, as evidenced by measurement results of two phase shifters (0–π and 0–2π, respectively). Such nonlinearities complicate the established FoM metrics and potentially lead to a renewed interest in the selection and material synthesis of LCs to optimise reconfigurable mmWave devices, and promote their technological exploitation in phased array systems targeting demanding applications such as inter-satellite links and satellite internet.

Three-Bit DMTL Phase Shifter for Phased Array Antennas

2019 ◽  
Vol 28 (07) ◽  
pp. 1950112
Author(s):  
N. M. Mary Sindhuja ◽  
S. Kanthamani
Keyword(s):  
Transmission Line ◽  
Phase Shifter ◽  
Phased Array ◽  
Rf Mems ◽  
Beam Steering ◽  
Coplanar Waveguide ◽  
Phase Shifters ◽  
Array Antenna ◽  
Phased Array Antenna ◽  
Rf Signal

RF MEMS phase shifter is a device that is used to modify the transmission phase of RF signal and provide signal control. Phase shifters are high-value components used in phased array antenna architectures. In phased array antenna the phase shifter is used to provide reliable electronic beam steering. The proposed 3-bit distributed MEMS transmission line (DMTL) phase shifter is designed using elevated coplanar waveguide (ECPW) transmission line for the first time, which results in better return loss of [Formula: see text]14.23[Formula: see text]dB and an average insertion loss of [Formula: see text]1.46[Formula: see text]dB. This paper discusses the development of ECPW-based 3-bit DMTL phase shifter designed to operate at 15[Formula: see text]GHz.

scholarly journals Direct antivirals working against the novel coronavirus: azithromycin (DAWn-AZITHRO), a randomized, multicenter, open-label, adaptive, proof-of-concept clinical trial of new antivirals working against SARS-CoV-2—azithromycin trial

Trials ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Iwein Gyselinck ◽  
◽  
Laurens Liesenborghs ◽  
Ewout Landeloos ◽  
Ann Belmans ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Standard Of Care ◽  
Ordinal Scale ◽  
Cytokine Signaling ◽  
Nasopharyngeal Swab ◽  
The Novel ◽  
Proof Of Concept ◽  
Open Label ◽  
Novel Coronavirus

Abstract Background The rapid emergence and the high disease burden of the novel coronavirus SARS-CoV-2 have created a medical need for readily available drugs that can decrease viral replication or blunt the hyperinflammatory state leading to severe COVID-19 disease. Azithromycin is a macrolide antibiotic, known for its immunomodulatory properties. It has shown antiviral effect specifically against SARS-CoV-2 in vitro and acts on cytokine signaling pathways that have been implicated in COVID-19. Methods DAWn-AZITHRO is a randomized, open-label, phase 2 proof-of-concept, multicenter clinical trial, evaluating the safety and efficacy of azithromycin for treating hospitalized patients with COVID-19. It is part of a series of trials testing promising interventions for COVID-19, running in parallel and grouped under the name DAWn-studies. Patients hospitalized on dedicated COVID wards are eligible for study inclusion when they are symptomatic (i.e., clinical or radiological signs) and have been diagnosed with COVID-19 within the last 72 h through PCR (nasopharyngeal swab or bronchoalveolar lavage) or chest CT scan showing typical features of COVID-19 and without alternate diagnosis. Patients are block-randomized (9 patients) with a 2:1 allocation to receive azithromycin plus standard of care versus standard of care alone. Standard of care is mostly supportive, but may comprise hydroxychloroquine, up to the treating physician’s discretion and depending on local policy and national health regulations. The treatment group receives azithromycin qd 500 mg during the first 5 consecutive days after inclusion. The trial will include 284 patients and recruits from 15 centers across Belgium. The primary outcome is time from admission (day 0) to life discharge or to sustained clinical improvement, defined as an improvement of two points on the WHO 7-category ordinal scale sustained for at least 3 days. Discussion The trial investigates the urgent and still unmet global need for drugs that may impact the disease course of COVID-19. It will either provide support or else justify the discouragement of the current widespread, uncontrolled use of azithromycin in patients with COVID-19. The analogous design of other parallel trials of the DAWN consortium will amplify the chance of identifying successful treatment strategies and allow comparison of treatment effects within an identical clinical context. Trial registration EU Clinical trials register EudraCT Nb 2020-001614-38. Registered on 22 April 2020

scholarly journals Waning antibody responses in COVID-19: what can we learn from the analysis of other coronaviruses?

Infection ◽  
2021 ◽  
Author(s):  
Ali Hamady ◽  
JinJu Lee ◽  
Zuzanna A. Loboda
Keyword(s):  
Cross Reactivity ◽  
Antibody Responses ◽  
The Novel ◽  
Incidence And Mortality ◽  
Antibody Titres ◽  
Human Coronaviruses ◽  
Public Health Strategies ◽  
Antibody Dynamics

Abstract Objectives The coronavirus disease 2019 (COVID-19), caused by the novel betacoronavirus severe acute respiratory syndrome 2 (SARS-CoV-2), was declared a pandemic in March 2020. Due to the continuing surge in incidence and mortality globally, determining whether protective, long-term immunity develops after initial infection or vaccination has become critical. Methods/Results In this narrative review, we evaluate the latest understanding of antibody-mediated immunity to SARS-CoV-2 and to other coronaviruses (SARS-CoV, Middle East respiratory syndrome coronavirus and the four endemic human coronaviruses) in order to predict the consequences of antibody waning on long-term immunity against SARS-CoV-2. We summarise their antibody dynamics, including the potential effects of cross-reactivity and antibody waning on vaccination and other public health strategies. At present, based on our comparison with other coronaviruses we estimate that natural antibody-mediated protection for SARS-CoV-2 is likely to last for 1–2 years and therefore, if vaccine-induced antibodies follow a similar course, booster doses may be required. However, other factors such as memory B- and T-cells and new viral strains will also affect the duration of both natural and vaccine-mediated immunity. Conclusion Overall, antibody titres required for protection are yet to be established and inaccuracies of serological methods may be affecting this. We expect that with standardisation of serological testing and studies with longer follow-up, the implications of antibody waning will become clearer.

A Novel Surgical Technique for Large Frontoencephalocele Management: The Mercy Ships Approach

FACE ◽  
2021 ◽  
pp. 273250162097932
Author(s):  
Naikhoba C. O. Munabi ◽  
Eric S. Nagengast ◽  
Gary Parker ◽  
Shaillendra A. Magdum ◽  
Mirjam Hamer ◽  
...  
Keyword(s):  
Surgical Technique ◽  
Intraoperative Complications ◽  
Complication Rates ◽  
The Novel ◽  
Middle Income ◽  
Middle Income Countries ◽  
Lumbar Drain ◽  
Cerebral Herniation ◽  
Long Nose

Background: Large frontoencephaloceles, more common in low and middle-income countries, require complex reconstruction of cerebral herniation, elongated nose, telecanthus, and cephalic frontal bone rotation. Previously described techniques involve multiple osteotomies, often fail to address cephalad brow rotation, and have high complication rates including up to 35% mortality. This study presents a novel, modified, single-staged technique for frontoencephalocele reconstruction performed by Mercy Ships. This technique, which addresses functional and aesthetic concerns with minimal osteotomies, may help improve outcomes in low resources settings. Methods: Retrospective review was performed of patients who underwent frontoencephalocele reconstruction through Mercy Ships using the technique described. Patient data including country, age, gender, associated diagnoses, and prior interventions were reviewed. Intraoperative and post-operative complications were recorded. Results: Eight patients with frontoencephalocele (ages 4-14 years) underwent surgery with the novel technique in 4 countries. Average surgical time was 6.0 ± 0.9 hours. No intraoperative complications occurred. Post-operatively 1 patient experienced lumbar drain dislodgement requiring replacement and a second had early post-operative fall requiring reoperation for hardware replacement. In person follow-up to 2.4 months showed no additional complications. Follow-up via phone at 1 to 2 years post-op revealed all patients who be satisfied with surgical outcomes. Conclusions: Reconstruction of large frontoencephaloceles can be challenging due to the need for functional closure of the defect and craniofacial reconstruction to correct medial hypertelorism, long nose deformity, and cephalad forehead rotation. The novel surgical technique presented in this paper allows for reliable reconstruction of functional and aesthetic needs with simplified incision design, osteotomies, and bandeau manipulation.

Synthese neuer Pyridin-C-nukleoside der 2 ,3 -Didesoxyribose durch „inverse“ [4+2]-Cycloaddition Synthesis of Novel Pyridine-C-nucleosides of 2,3-Dideoxyribose by „Inverse“ [4+2]-Cycloaddition

1997 ◽  
Vol 52 (7) ◽  
pp. 851-858 ◽  
Author(s):  
Gunther Seitz ◽  
Johanna Siegl
Keyword(s):  
Cycloaddition Reaction ◽  
Alder Reaction ◽  
Diels Alder ◽  
The Novel ◽  
Protecting Group ◽  
Enol Ethers ◽  
Inverse Electron Demand ◽  
Diels Alder Reaction ◽  
Cyclic Ketene Acetals

The anomeric imido esters 5 and 6, appropriate precursors for C-nucleoside synthesis, were prepared and utilized as heterodienophiles in a Diels-Alder reaction with inverse electron demand to yield the novel, protected 1.2.4-triazine C-nucleosides 8 and 9. They could be deprotected by treatment with 70% trifluoroacetic acid to furnish the free C-nucleosides 10 and 11. The triazine „aglycon“ of 8 contains an electron deficient diazadiene system, highly activated to react with various electron rich dienophiles such as enamines, enol ethers and several cyclic ketene acetals in an „inverse“ [4+2]-cycloaddition reaction. The Diels-Alder adducts spontaneously eliminate N2 and after follow-up reactions the O-TBDPS protected pyridine-C-nucleosides 13, 15, 17,19, 21 and 23 are formed. Removal of the protecting group by treatment with CF3CO2H /H2O leads to the corresponding 2’,3’-dideoxy-β-D-ribofuranosyl- pyridines.

scholarly journals SARS-CoV-2/DENV co-infection: a series of cases from the Federal District, Midwestern Brazil

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Heidi Luise Schulte ◽  
José Diego Brito-Sousa ◽  
Marcus Vinicius Guimarães Lacerda ◽  
Luciana Ansaneli Naves ◽  
Eliana Teles de Gois ◽  
...  
Keyword(s):  
Clinical Signs ◽  
Federal District ◽  
Therapeutic Interventions ◽  
Diagnostic Process ◽  
The Novel ◽  
Prevention Measures ◽  
Laboratory Findings ◽  
Novel Coronavirus ◽  
The Impact

Abstract Background Since the novel coronavirus disease outbreak, over 179.7 million people have been infected by SARS-CoV-2 worldwide, including the population living in dengue-endemic regions, particularly Latin America and Southeast Asia, raising concern about the impact of possible co-infections. Methods Thirteen SARS-CoV-2/DENV co-infection cases reported in Midwestern Brazil between April and September of 2020 are described. Information was gathered from hospital medical records regarding the most relevant clinical and laboratory findings, diagnostic process, therapeutic interventions, together with clinician-assessed outcomes and follow-up. Results Of the 13 cases, seven patients presented Acute Undifferentiated Febrile Syndrome and six had pre-existing co-morbidities, such as diabetes, hypertension and hypopituitarism. Two patients were pregnant. The most common symptoms and clinical signs reported at first evaluation were myalgia, fever and dyspnea. In six cases, the initial diagnosis was dengue fever, which delayed the diagnosis of concomitant infections. The most frequently applied therapeutic interventions were antibiotics and analgesics. In total, four patients were hospitalized. None of them were transferred to the intensive care unit or died. Clinical improvement was verified in all patients after a maximum of 21 days. Conclusions The cases reported here highlight the challenges in differential diagnosis and the importance of considering concomitant infections, especially to improve clinical management and possible prevention measures. Failure to consider a SARS-CoV-2/DENV co-infection may impact both individual and community levels, especially in endemic areas.

scholarly journals The aiming device for cervical distractor pin insertion: a proof-of-concept, feasibility study

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Torphong Bunmaprasert ◽  
Sittichai Luangkittikong ◽  
Menghong Tosinthiti ◽  
Supachoke Nivescharoenpisan ◽  
Raphi Raphitphan ◽  
...  
Keyword(s):  
Radiation Exposure ◽  
Feasibility Study ◽  
Vertebral Body ◽  
The Novel ◽  
Cervical Lordosis ◽  
Proof Of Concept ◽  
Entry Points ◽  
Free Hand Technique ◽  
Anterior Discectomy And Fusion ◽  
Vertebral Endplates

Abstract Background Restoration of cervical lordosis after anterior discectomy and fusion is a desirable goal. Proper insertion of the vertebral distraction or Caspar pin can assist lordotic restoration by either putting the tips divergently or parallel to the index vertebral endplates. With inexperienced surgeons, the traditional free-hand technique for Caspar pin insertion may require multiple insertion attempts that may compromise the vertebral body and increase radiation exposure during pin localization. Our purpose is to perform a proof-of-concept, feasibility study to evaluate the effectiveness of a pin insertion aiming device for vertebral distraction pin insertion. Methods A Smith-Robinson approach and anterior cervical discectomy were performed from C3 to C7 in 10 human cadaveric specimens. Caspar pins were inserted using a novel pin insertion aiming device at C3-4, C4-5, C5-6, and C6-7. The angles between the cervical endplate slope and Caspar pin alignment were measured with lateral cervical imaging. Results The average Superior Endplate-to-Caspar Pin angle (SE-CP) and the average Inferior Endplate-to-Caspar Pin angle (IE-CP) were 6.2 ± 2.0° and 6.3 ± 2.2° respectively. For the proximal pins, the SE-CP and the IE-CP were 4.0 ± 1.1°and 5.2 ± 2.4° respectively. For the distal pins, the SE-CP and the IE-CP were 7.7 ± 1.4° and 6.2 ± 2.0° respectively. No cervical endplate violations occurred. Conclusion The novel Caspar pin insertion aiming device can control the pin entry points and pin direction with the average SE-CP and average IE-CP of 6.2 ± 2.0° and 6.3 ± 2.2°, respectively. The study shows that the average different angles between the Caspar pin and cervical endplate are less than 7°.

Sign in / Sign up

Export Citation Format

Share Document