A Low-Loss Coaxial Cavity Microwave Bandpass Filter with Post-Manufacturing Tuning Capabilities

This paper presents a low-loss coaxial cavity microwave bandpass filter with post-manufacturing tuning capabilities. A systematic filter development using a low-pass prototype as the starting point to produce a fourth-degree Chebyshev bandpass response is demonstrated. The coaxial cavity filter based on the transverse electromagnetic mode of the propagation has a center frequency of 2.5 GHz and a bandwidth of 160 MHz. An insertion loss (S21) of 0.15 dB and a return loss (S11) better than 15 dB are obtained, particularly in the passband. An excellent agreement between ideal circuit, EM simulation and measurement results has been achieved. The filter is then modified to have two channels, known as a diplexer, wherein center frequencies are at 2.5 GHz and 2.9 GHz at a bandwidth of 200 MHz. This type of microwave filter will be useful in any microwave system wherein low insertion loss and high selectivity are crucial, such as in base station, radar, and satellite transceivers

Dynamical behavior of a cancer growth model with chemotherapy and boosting of the immune system

In this study, we set up and analyze a cancer growth model that integrates a chemotherapy drug with the impact of vitamins in boosting and strengthening the immune system. The aim of this study is to determine the minimal amount of treatment required to eliminate cancer, which will help to reduce harm to patients. It is assumed that vitamins come from organic foods and beverages. The chemotherapy drug is added to delay and eliminate tumor cell growth and division. To that end, we suggest the tumor-immune model, composed of the interaction of tumor and immune cells, which is composed of two ordinary differential equations. The model’s fundamental mathematical properties, such as positivity, boundedness, and equilibrium existence, are examined. The equilibrium points’ asymptotic stability is analyzed using linear stability. Then, global stability and persistence are investigated using the Lyapunov strategy. The occurrence of bifurcations of the model, such as of trans-critical or Hopf type, is also explored. Numerical simulations are used to verify the theoretical analysis. The Runge–Kutta method of fourth order is used in the simulation of the model. The analytical study and simulation findings show that the immune system is boosted by regular vitamin consumption, inhibiting the growth of tumor cells. Further, the chemotherapy drug contributes to the control of tumor cell progression. Vitamin intake and chemotherapy are treated both individually and in combination, and in all situations, the minimal level required to eliminate the cancer is determined

Correlation Between Polymer Packing And Gas Transport Properties For Co2/N2 Separation In Glassy Fluorinated Polyimide Membrane

Gas separation performance of a membrane highly hinges on its physical properties. In this study, the interplay between polymer packing of a membrane and its gas transport behaviours (permeability and selectivity) was investigated through a series of 6FDA-DAM:DABA (3:2) polyimide membranes with different polymer compactness. The chemical structure and the polymer packing of the resulting membrane were characterized using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and packing density measurement, respectively. CO2/N2 separation efficiency of the membrane was evaluated at 25oC with feed pressure up to 6 bar. N2 permeability was found to rely on the membrane’s packing density, which signified its greater dependence on molecular sieving. In contrast, sorption showed a more vital role in determining the CO2 permeability. In this work, the membrane with a final thickness of 97±2 μm had successfully surpassed the Robeson’s 2008 upper bound plot with a CO2 permeability of 83 Barrer and CO2/N2 selectivity of 97 at 3 bar permeation

Recent Trends on Dual- and Triple-Band Microwave Filters for Wireless Communications

In the past few years, several designs of dual- and triple-band microwave filters satisfying various objectives have been proposed for wireless communication. Several designs are new concepts, whereas others are inspired from previous works. The development trends of these designs can be reviewed from this compilation of studies. This paper begins with an explanation of dual- and triple-band microwave filters, followed by a discussion on several designs in terms of size, measurement, performance, and technology use. Among various designs, microstrip band-pass filters are extensively used because of their simple design procedures and because they can be integrated into circuits easily. Furthermore, most researchers use low frequencies in their designs because of the demands of current wireless applications. Finally, designs are proposed to produce compact microwave filters with good performance

The development of an ecofriendly binder containing high volume of cement replacement by incorporating two by-product materials for the use in soil stabilization

The development of an ecofriendly binder containing high volume of cement replacement by incorporating two waste materials for the use in soil stabilization. This paper investigates the possibility of replacing ordinary Portland cement (OPC) by two waste and by-product materials for the use of a silty clay soil stabilization purpose. The soil was treated by 9.0% OPC where this mixture was used as a reference for all tests. Two by - product materials: ground granulated blast furnace slag and cement kiln dust were used as replacement materials. Consistency limits, compaction and unconfined compression strength (UCS) tests were conducted. Scanning electron microscopy (SEM) analysis was carried out for the proposed binder to investigate the reaction of products over curing time. Seven curing periods were adopted for all mixtures; 1, 3, 7, 14, 28, 52, and 90 days. The results showed that the strength development over curing periods after cement replacement up to 45-60% was closed to those of the reference specimens. The microphotographs of SEM analysis showed that the formation of Ettringite and Portladite as well as to calcium silicate hydrate gel was obvious at curing periods longer than 7 days reflected that the replacing materials succeed to produce the main products necessary for binder formation

Tuning of persulfate activation from free radical to non-radical pathway through the incorporation of non-redox magnesium oxide

This is the author accepted manuscript.Nonradical-based advanced oxidation processes for pollutants removal have attracted much attention due to their inherent advantages. Herein we report that magnesium oxides (MgO) in CuOMgO/Fe3O4 not only enhanced the catalytic properties but also switched the free radical peroxymonosulfate-activated process into the 1O2 based nonradical process. CuOMgO/Fe3O4 catalyst exhibited consistent performance in a wide pH range from 5.0 to 10.0, and the degradation kinetics were not inhibited by the common free radical scavengers, anions or natural organic matter. Quantitative structure activity relationships (QSARs) revealed the relationship between the degradation rate constant of 14 substituted phenols and their conventional descriptor variables (i.e. Hammett constants σ, σ−, σ+), half-wave oxidation potential (E1/2) and pKa values. QSARs together with kinetic isotopic effect (KIE) recognized the electron transfer as the dominant oxidation process. Characterizations and DFT calculation indicated that the incorporated MgO alters the copper sites to highly oxidized metals centers, offering a more suitable platform for PMS to generate metastable copper intermediates. This highly oxidized metals centers of copper played the key role in producing O2•− after accepting electron from another PMS molecule, and finally 1O2 as sole reactive species was generated from the direct oxidation of O2•− through thermodynamically feasible reactions.National Key R&D Program of ChinaNational Science Foundation of ChinaFundamental Research Funds for the Central Universitie

Machine Learning based Energy Management Model for Smart Grid and Renewable Energy Districts

The combination of renewable energy sources and prosumer-based smart grid is a sustainable solution to cater to the problem of energy demand management. A pressing need is to develop an efficient Energy Management Model (EMM) that integrates renewable energy sources with smart grids. However, the variable scenarios and constraints make this a complex problem. Machine Learning (ML) methods can often model complex and non-linear data better than the statistical models. Therefore, developing an ML algorithm for the EMM is a suitable option as it reduces the complexity of the EMM by developing a single trained model to predict the performance parameters of EMM for multiple scenarios. However, understanding latent correlations and developing trust in highly complex ML models for designing EMM within the stochastic prosumer-based smart grid is still a challenging task. Therefore, this paper integrates ML and Gaussian Process Regression (GPR) in the EMM. At the first stage, an optimization model for Prosumer Energy Surplus (PES), Prosumer Energy Cost (PEC), and Grid Revenue (GR) is formulated to calculate base performance parameters (PES, PEC, and GR) for the training of the ML-based GPR model. In the second stage, stochasticity of renewable energy sources, load, and energy price, same as provided by the Genetic Algorithm (GA) based optimization model for PES, PEC, and GR, and base performance parameters act as input covariates to produce a GPR model that predicts PES, PEC, and GR. Seasonal variations of PES, PEC, and GR are incorporated to remove hitches from seasonal dynamics of prosumers energy generation and prosumers energy consumption. The proposed adaptive Service Level Agreement (SLA) between energy prosumers and the grid benefits both these entities. The results of the proposed model are rigorously compared with conventional optimization (GA and PSO) based EMM to prove the validity of the proposed model

The burden of diabetes mellitus during pregnancy in low- and middle-income countries : a systematic review

Peer reviewedPublisher PD

Upper limb nerve transfer surgery in patients with tetraplegia

IMPORTANCE: Cervical spinal cord injury (SCI) causes devastating loss of upper extremity function and independence. Nerve transfers are a promising approach to reanimate upper limbs; however, there remains a paucity of high-quality evidence supporting a clinical benefit for patients with tetraplegia. OBJECTIVE: To evaluate the clinical utility of nerve transfers for reanimation of upper limb function in tetraplegia. DESIGN, SETTING, AND PARTICIPANTS: In this prospective case series, adults with cervical SCI and upper extremity paralysis whose recovery plateaued were enrolled between September 1, 2015, and January 31, 2019. Data analysis was performed from August 2021 to February 2022. INTERVENTIONS: Nerve transfers to reanimate upper extremity motor function with target reinnervation of elbow extension and hand grasp, pinch, and/or release. MAIN OUTCOMES AND MEASURES: The primary outcome was motor strength measured by Medical Research Council (MRC) grades 0 to 5. Secondary outcomes included Sollerman Hand Function Test (SHFT); Michigan Hand Outcome Questionnaire (MHQ); Disabilities of Arm, Shoulder, and Hand (DASH); and 36-Item Short Form Health Survey (SF-36) physical component summary (PCS) and mental component summary (MCS) scores. Outcomes were assessed up to 48 months postoperatively. RESULTS: Twenty-two patients with tetraplegia (median age, 36 years [range, 18-76 years]; 21 male [95%]) underwent 60 nerve transfers on 35 upper limbs at a median time of 21 months (range, 6-142 months) after SCI. At final follow-up, upper limb motor strength improved significantly: median MRC grades were 3 (IQR, 2.5-4; P = .01) for triceps, with 70% of upper limbs gaining an MRC grade of 3 or higher for elbow extension; 4 (IQR, 2-4; P \u3c .001) for finger extensors, with 79% of hands gaining an MRC grade of 3 or higher for finger extension; and 2 (IQR, 1-3; P \u3c .001) for finger flexors, with 52% of hands gaining an MRC grade of 3 or higher for finger flexion. The secondary outcomes of SHFT, MHQ, DASH, and SF36-PCS scores improved beyond the established minimal clinically important difference. Both early (\u3c12 months) and delayed (≥12 months) nerve transfers after SCI achieved comparable motor outcomes. Continual improvement in motor strength was observed in the finger flexors and extensors across the entire duration of follow-up. CONCLUSIONS AND RELEVANCE: In this prospective case series, nerve transfer surgery was associated with improvement of upper limb motor strength and functional independence in patients with tetraplegia. Nerve transfer is a promising intervention feasible in both subacute and chronic SCI

A mineralogical study in contrasts: highly mineralized whale rostrum and human enamel

The outermost enamel of the human tooth and the rostrum of the whale Mesoplodon densirostris are two highly mineralized tissues that contain over 95wt.% mineral, i.e., bioapatite. However, the same mineral type (carbonated hydroxylapatite) does not yield the same material properties, as revealed by Raman spectroscopy, scanning electron microscopy, electron microprobe analysis, and synchrotron X-ray diffraction analysis. Overall, the outermost enamel of a tooth has more homogeneous physical and chemical features than the rostrum. Chemical comparison of rostrum and enamel shows bioapatite in the rostrum to be enriched in Na, Mg, CO3, and S, whereas the outermost enamel shows only a slightly enriched Cl concentration. Morphologically, mineral rods (at tens of μm scale), crystallites and prisms (at μm and sub-μm scale), and platelets (at tens of nm scale) all demonstrate less organized texture in the rostrum than in enamel. Such contrasts between two mineralized tissues suggest distinct pathways of biomineralization, e.g., the nature of the equilibrium between mineral and body fluid. This study illustrates the remarkable flexibility of the apatite mineral structure to match its chemical and physical properties to specific biological needs within the same animal or between species.The work was partially funded by NIH grant 1R21AR055184-01A2 and SRF for ROCS, SEM