scholarly journals The Development of Frequency Tripler Based on Six-Anode Schottky Varactors

Micromachines ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1490
Author(s):  
Yuhang Li ◽  
Jin Meng ◽  
Dehai Zhang ◽  
Haotian Zhu
Keyword(s):  
Output Power ◽  
Impedance Matching ◽  
Three Dimensional ◽  
Input Power ◽  
Frequency Multiplier ◽  
Dimensional Structure ◽  
Basic Design ◽  
Peak Output Power ◽  
The Impact ◽  
Multiplier Circuit

The development of a millimeter-wave unbalanced frequency tripler based on the nonlinear characteristics of planar Schottky varactors is presented. The entire module is designed by hybrid integration. A frequency multiplier circuit model was established to reflect the influence of diode parameters and the impedance matching on the multiplier in different frequency bands. The effect of junction imbalance on the output power of the frequency multiplier was investigated and the multiplier was improved based on the basic design. The addition of a cut microstrip stub in the improved diode unit reduced the impact of a power imbalance on frequency multiplier performance. The characteristics of the multiplier circuit were analyzed by the full-wave electromagnetic simulation of the three-dimensional structure and the harmonic balance simulation of the circuit. Test results showed that the peak output power of the improved frequency tripler was 12.6 mW at 277 GHz with an input power of 200 mW, an effective 12% improvement over the basic design.

scholarly journals A G-Band High Output Power and Wide Bandwidth Sheet Beam Extended Interaction Klystron Design Operating at TM31 with 2π Mode

Electronics ◽  
2021 ◽  
Vol 10 (16) ◽  
pp. 1948
Author(s):  
Shasha Li ◽  
Feng Zhang ◽  
Cunjun Ruan ◽  
Yiyang Su ◽  
Pengpeng Wang
Keyword(s):  
Output Power ◽  
Characteristic Impedance ◽  
Great Influence ◽  
Operating Mode ◽  
High Order Mode ◽  
Input Power ◽  
Mode Competition ◽  
Tuning Method ◽  
Peak Output Power ◽  
Extended Interaction

In this paper, we propose a high-order mode sheet beam extended interaction klystron (EIK) operating at G-band. Through the study of electric field distribution, we choose TM31 2π mode as the operating mode. The eigenmode simulation shows that the resonant frequency of the modes adjacent to the operating mode is far away from the central frequency, so there is almost no mode competition in our high mode EIK. In addition, by studying the sensitivity of the related geometry parameters, we conclude that the height of the coupling cavity has a great influence on the effective characteristic impedance, and the width of the gap mainly affects the working frequency. Therefore, it is necessary to strictly control the fabrication tolerance within 2 μm. Finally, the RF circuit using six barbell multi-gap cavities is determined, with five gaps for the input cavity and idler cavities and seven gaps for the output cavity. To expand the bandwidth, the stagger tuning method is adopted. Under the conditions of a voltage of 16.5 kV, current of 0.5 A and input power of 0.2 W, the peak output power of 650 W and a 3-dB bandwidth of 700 MHz are achieved without any self-oscillation.

A broadband 23.1 ∼ 27.2 GHz doherty power amplifier with peak output power of 24.3 dBm

Circuit World ◽  
2019 ◽  
Vol 46 (1) ◽  
pp. 1-5
Author(s):  
Yanfeng Fang ◽  
Yijiang Zhang
Keyword(s):  
Output Power ◽  
Power Amplifier ◽  
Input Power ◽  
Content Type ◽  
Fully Integrated ◽  
Power Added Efficiency ◽  
Peak Output Power ◽  
Saturated Output Power ◽  
Direct Input ◽  
Matching Techniques

Purpose This paper aims to implement a new high output power fully integrated 23.1 to 27.2 GHz gallium arsenide heterojunction bipolar transistor power amplifier (PA) to meet the stringent linearity requirements of LTE systems. Design/methodology/approach The direct input power dividing technique is used on the chip. Broadband input and output matching techniques are used for broadband Doherty operation. Findings The PA achieves a small-signal gain of 22.8 dB at 25.1 GHz and a saturated output power of 24.3 dBm at 25.1 GHz with a maximum power added efficiency of 31.7%. The PA occupies 1.56 mm2 (including pads) and consumes a maximum current of 79.91 mA from a 9 V supply. Originality/value In this paper, the author proposed a novel direct input dividing technique with broadband matching circuits using a low Q output matching technique, and demonstrated a fully-integrated Doherty PA across frequencies of 23.1∼27.2 GHz for long term evolution-license auxiliary access (LTE-LAA) handset applications.

scholarly journals Susceptibility of protein therapeutics to spontaneous chemical modifications by oxidation, cyclization, and elimination reactions

Amino Acids ◽  
2019 ◽  
Vol 51 (10-12) ◽  
pp. 1409-1431 ◽  
Author(s):  
Luigi Grassi ◽  
Chiara Cabrele
Keyword(s):  
Small Molecules ◽  
Three Dimensional ◽  
Drug Market ◽  
Structure And Function ◽  
Dimensional Structure ◽  
Chemical Modifications ◽  
Small Molecule Drugs ◽  
And Function ◽  
The Impact

Abstract Peptides and proteins are preponderantly emerging in the drug market, as shown by the increasing number of biopharmaceutics already approved or under development. Biomolecules like recombinant monoclonal antibodies have high therapeutic efficacy and offer a valuable alternative to small-molecule drugs. However, due to their complex three-dimensional structure and the presence of many functional groups, the occurrence of spontaneous conformational and chemical changes is much higher for peptides and proteins than for small molecules. The characterization of biotherapeutics with modern and sophisticated analytical methods has revealed the presence of contaminants that mainly arise from oxidation- and elimination-prone amino-acid side chains. This review focuses on protein chemical modifications that may take place during storage due to (1) oxidation (methionine, cysteine, histidine, tyrosine, tryptophan, and phenylalanine), (2) intra- and inter-residue cyclization (aspartic and glutamic acid, asparagine, glutamine, N-terminal dipeptidyl motifs), and (3) β-elimination (serine, threonine, cysteine, cystine) reactions. It also includes some examples of the impact of such modifications on protein structure and function.

scholarly journals SphereCon—a method for precise estimation of residue relative solvent accessible area from limited structural information

2020 ◽  
Vol 36 (11) ◽  
pp. 3372-3378
Author(s):  
Alexander Gress ◽  
Olga V Kalinina
Keyword(s):  
Protein Function ◽  
Structural Information ◽  
Solvent Accessibility ◽  
Three Dimensional ◽  
Structural Data ◽  
Supplementary Information ◽  
Dimensional Structure ◽  
Relative Solvent Accessibility ◽  
Precise Measure ◽  
The Impact

Abstract Motivation In proteins, solvent accessibility of individual residues is a factor contributing to their importance for protein function and stability. Hence one might wish to calculate solvent accessibility in order to predict the impact of mutations, their pathogenicity and for other biomedical applications. A direct computation of solvent accessibility is only possible if all atoms of a protein three-dimensional structure are reliably resolved. Results We present SphereCon, a new precise measure that can estimate residue relative solvent accessibility (RSA) from limited data. The measure is based on calculating the volume of intersection of a sphere with a cone cut out in the direction opposite of the residue with surrounding atoms. We propose a method for estimating the position and volume of residue atoms in cases when they are not known from the structure, or when the structural data are unreliable or missing. We show that in cases of reliable input structures, SphereCon correlates almost perfectly with the directly computed RSA, and outperforms other previously suggested indirect methods. Moreover, SphereCon is the only measure that yields accurate results when the identities of amino acids are unknown. A significant novel feature of SphereCon is that it can estimate RSA from inter-residue distance and contact matrices, without any information about the actual atom coordinates. Availability and implementation https://github.com/kalininalab/spherecon. Contact [email protected] Supplementary information Supplementary data are available at Bioinformatics online.

A 280-325 GHz Frequency Multiplier Chain With 2.5 dBm Peak Output Power

2019 ◽  
Author(s):  
Peigen Zhou ◽  
Jixin Chen ◽  
Pinpin Yan ◽  
Zhe Chen ◽  
Debin Hou ◽  
...  
Keyword(s):  
Output Power ◽  
Frequency Multiplier ◽  
Peak Output Power

scholarly journals Two Pathogenic Gene Mutations Identified Associating with Congenital Cataract and Iris Coloboma Respectively in a Chinese Family

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Bin Li ◽  
Bin Lu ◽  
Xuewen Guo ◽  
Shenghui Hu ◽  
Guihu Zhao ◽  
...  
Keyword(s):  
Congenital Cataract ◽  
Three Dimensional ◽  
Gene Mutations ◽  
Dimensional Structure ◽  
Chinese Family ◽  
Control Group ◽  
Three Dimensional Structure ◽  
Han Ethnicity ◽  
The Family ◽  
The Impact

Purpose. To screen out pathogenic genes in a Chinese family with congenital cataract and iris coloboma. Material and Methods. A three-generation family with congenital cataract and iris coloboma from a Han ethnicity was recruited. DNA was extracted from peripheral blood samples collected from all individuals in the family. Whole exon sequencing was employed for screening the disease-causing gene mutations in the proband, and Sanger sequencing was used for other members of the family and a control group of 500 healthy individuals. Bioinformatics analysis and three-dimensional structure predictions were used to predict the impact of amino acid changes on protein structure and function. Results. The candidate genes of cataract and iris coloboma were successfully screened out. A heterozygote mutation, CRYGD c.70C>A (p.P24T), was identified as cosegregating with congenital cataracts, while another heterozygous mutation, WFS1 c.1514G>C (p.C505S), which had not been reported previously, cosegregated with congenital iris coloboma. Bioinformatic analyses and three-dimensional structure prediction proved that the three-dimensional structures of WFS1 p.C505S and CRYGD p.P24T changed markedly and may contribute significantly to iris coloboma and congenital cataract, respectively. Conclusions. We report a novel mutation, WFS1 p.C505S, and a known mutation, CRYGD p.P24T, that cosegregate with iris coloboma and congenital cataract, respectively, in a Chinese family. This is the first time the association of WFS1 p.C505S with iris coloboma has been demonstrated, although CRYGD p.P24T has been widely reported as being associated with congenital cataract, especially in the Eastern Asian population. These findings may have future therapeutic benefit for the diagnosis of iris coloboma and congenital cataract. The results may also be relevant in further studies aiming to investigate the molecular pathogenesis of iris coloboma and congenital cataract.

scholarly journals Novel biological implication of a strictly monomorphic GCC repeat in the human PRKACB gene

2021 ◽  
Author(s):  
Safoura Khamse ◽  
Zahra Jafarian ◽  
Ali Bozorgmehr ◽  
Mostafa Tavakoli ◽  
Hossein Afshar Iranian ◽  
...  
Keyword(s):  
Late Onset ◽  
Human Subjects ◽  
Three Dimensional ◽  
Dna Structure ◽  
Dimensional Structure ◽  
Protein Coding ◽  
Three Dimensional Structure ◽  
Significant Divergence ◽  
The Impact ◽  
The Brain

Abstract Across human protein-coding genes, PRKACB (Protein Kinase CAMP-Activated Catalytic Subunit Beta) contains one of the longest GCC-repeats, and is predominantly expressed in the brain. Here we studied this STR in 300 human subjects, consisting of late-onset neurocognitive disorder (NCD) (N = 150) and controls (N = 150). We also studied the impact of this STR on the three-dimensional structure of DNA. While the PRKACB GCC-STR was strictly monomorphic at 7-repeats, we detected two 7/8 genotypes only in the NCD group. In comparison to all other lengths, (GCC)7 had the least effect on the three-dimensional structure of DNA, evidenced by minimal divergence between 0 and 7-repeats (divergence score = 0.04) and significant divergence between 0 and 8 repeats (divergence score = 0.50). A similar inert effect to the GCC-repeat was not detected in other classes of STRs such as GA and CA repeats. In conclusion, we report monomorphism of an exceptionally long GCC repeat in the PRKACB gene in human, its inert effect on DNA structure, and divergence in two cases of late-onset NCD. This is the first indication of natural selection for an exceptionally long monomorphic GCC-repeat, which probably evolved to function as an “epigenetic knob”, without changing the regional DNA structure.

scholarly journals Deep geometric representations for modeling effects of mutations on protein-protein binding affinity

2021 ◽  
Vol 17 (8) ◽  
pp. e1009284
Author(s):  
Xianggen Liu ◽  
Yunan Luo ◽  
Pengyong Li ◽  
Sen Song ◽  
Jian Peng
Keyword(s):  
Protein Binding ◽  
Binding Affinity ◽  
Protein Design ◽  
Protein Structures ◽  
Three Dimensional ◽  
Point Mutations ◽  
Dimensional Structure ◽  
Gradient Boosting ◽  
Benchmark Datasets ◽  
The Impact

Modeling the impact of amino acid mutations on protein-protein interaction plays a crucial role in protein engineering and drug design. In this study, we develop GeoPPI, a novel structure-based deep-learning framework to predict the change of binding affinity upon mutations. Based on the three-dimensional structure of a protein, GeoPPI first learns a geometric representation that encodes topology features of the protein structure via a self-supervised learning scheme. These representations are then used as features for training gradient-boosting trees to predict the changes of protein-protein binding affinity upon mutations. We find that GeoPPI is able to learn meaningful features that characterize interactions between atoms in protein structures. In addition, through extensive experiments, we show that GeoPPI achieves new state-of-the-art performance in predicting the binding affinity changes upon both single- and multi-point mutations on six benchmark datasets. Moreover, we show that GeoPPI can accurately estimate the difference of binding affinities between a few recently identified SARS-CoV-2 antibodies and the receptor-binding domain (RBD) of the S protein. These results demonstrate the potential of GeoPPI as a powerful and useful computational tool in protein design and engineering. Our code and datasets are available at: https://github.com/Liuxg16/GeoPPI.

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