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Cryptic species are commonly misidentified because of high morphological similarities to other species. One group of plants that may harbor large numbers of cryptic species is the quillworts (Isoëtes spp.), an ancient aquatic plant lineage. Although over 350 species of Isoëtes have been reported globally, only ten species have been recorded in China. The aim of this study is to better understand Isoëtes species diversity in China. For this purpose, we systematically explored the phylogeny and evolution of Isoëtes using complete chloroplast genome (plastome) data, spore morphology, chromosome number, genetic structure, and haplotypes of almost all Chinese Isoëtes populations. We identified three ploidy levels of Isoëtes in China—diploid (2n = 22), tetraploid (2n = 44), and hexaploid (2n = 66). We also found four megaspore and microspore ornamentation types in diploids, six in tetraploids, and three in hexaploids. Phylogenetic analyses confirmed that I. hypsophila as the ancestral group of the genus and revealed that Isoëtes diploids, tetraploids, and hexaploids do not form monophyletic clades. Most individual species possess a single genetic structure; however, several samples have conflicting positions on the phylogenetic tree based on SNPs and the tree based on plastome data. All 36 samples shared 22 haplotypes. Divergence time analysis showed that I. hypsophila diverged in the early Eocene (∼48.05 Ma), and most other Isoëtes species diverged 3–20 Ma. Additionally, different species of Isoëtes were found to inhabit different water systems and environments along the Yangtze River. These findings provide new insights into the relationships among Isoëtes species in China, where highly similar morphologic populations may harbor many cryptic species.

This work determined and analyzed the complete chloroplast genome sequence of Ceratopteris thalictroides (Linnaeus) Brongniart 1822 (Pteridaceae). The results indicate that the total chloroplast genome size of C. thalictroides is 149,399 bp in length, and the genome contains a large single-copy (LSC) region of 83,580 bp, a small single-copy (SSC) region of 21,241 bp, and a pair of inverted repeat (IR) regions of 22,289 bp. The GC content of C. thalictroides is 36.7%. The genome encodes a total of 131 unique genes, including 82 protein-coding genes, 38 tRNA genes, and 8 rRNA genes. The phylogenetic analysis results strongly suggest that C. thalictroides is closely related to C. cornuta.

Lycophytes are an ancient clade of the non-flowering vascular plants with chromosome numbers that vary from tens to hundreds. They are an excellent study system for examining whole-genome duplications (WGDs), or polyploidization, in spore-dispersed vascular plants. However, a lack of genome sequence data limits the reliable detection of very ancient WGDs, small-scale duplications (SSDs), and recent WGDs. Here, we integrated phylogenomic analysis and the distribution of synonymous substitutions per synonymous sites (Ks) of the transcriptomes of 13 species of lycophytes to identify, locate, and date multiple WGDs in the lycophyte family Lycopodiaceae. Additionally, we examined the genus Phlegmariurus for signs of genetic discordance, which can provide valuable insight into the underlying causes of such conflict (e.g., hybridization, incomplete lineage sorting, or horizontal gene transfer).We found strong evidence that two WGD events occurred along the phylogenetic backbone of Lycopodiaceae, with one occurring in the common ancestor of extant Phlegmariurus (Lycopodiaceae) approximately 22–23 million years ago (Mya) and the other occurring in the common ancestor of Lycopodiaceae around 206–214 Mya. Interestingly, we found significant genetic discordance in the genus Phlegmariurus, indicating that the genus has a complex evolutionary history. This study provides molecular evidence for multiple WGDs in Lycopodiaceae and offers phylogenetic clues to the evolutionary history of Lycopodiaceae.

Ferns and lycophytes have remarkably large genomes. However, little is known about how their genome size evolved in fern lineages. To explore the origins and evolution of chromosome numbers and genome size in ferns, we used flow cytometry to measure the genomes of 240 species (255 samples) of extant ferns and lycophytes comprising 27 families and 72 genera, of which 228 species (242 samples) represent new reports. We analyzed correlations among genome size, spore size, chromosomal features, phylogeny, and habitat type preference within a phylogenetic framework. We also applied ANOVA and multinomial logistic regression analysis to preference of habitat type and genome size. Using the phylogeny, we conducted ancestral character reconstruction for habitat types and tested whether genome size changes simultaneously with shifts in habitat preference. We found that 2C values had weak phylogenetic signal, whereas the base number of chromosomes (x) had a strong phylogenetic signal. Furthermore, our analyses revealed a positive correlation between genome size and chromosome traits, indicating that the base number of chromosomes (x), chromosome size, and polyploidization may be primary contributors to genome expansion in ferns and lycophytes. Genome sizes in different habitat types varied significantly and were significantly correlated with habitat types; specifically, multinomial logistic regression indicated that species with larger 2C values were more likely to be epiphytes. Terrestrial habitat is inferred to be ancestral for both extant ferns and lycophytes, whereas transitions to other habitat types occurred as the major clades emerged. Shifts in habitat types appear be followed by periods of genomic stability. Based on these results, we inferred that habitat type changes and multiple whole-genome duplications have contributed to the formation of large genomes of ferns and their allies during their evolutionary history.

BackgroundSeveral models have been developed to predict the severity and prognosis of chronic obstructive pulmonary disease (COPD). This study aimed to identify potential predictors and construct a prediction model for COPD severity using biochemical and immunological parameters.MethodsA total of 6,274 patients with COPD were recruited between July 2010 and July 2018. COPD severity was classified into mild, moderate, severe, and very severe based on the Global Initiative for Chronic Obstructive Lung Disease guidelines. A multivariate logistic regression model was constructed to identify predictors of COPD severity. The predictive ability of the model was assessed by measuring sensitivity, specificity, accuracy, and concordance.ResultsOf 6,274 COPD patients, 2,644, 2,600, and 1,030 had mild/moderate, severe, and very severe disease, respectively. The factors that could distinguish between mild/moderate and severe cases were vascular disorders (OR: 1.44; P < 0.001), high-density lipoprotein (HDL) (OR: 1.83; P < 0.001), plasma fibrinogen (OR: 1.08; P = 0.002), fructosamine (OR: 1.12; P = 0.002), standard bicarbonate concentration (OR: 1.09; P < 0.001), partial pressure of carbon dioxide (OR: 1.09; P < 0.001), age (OR: 0.97; P < 0.001), eosinophil count (OR: 0.66; P = 0.042), lymphocyte ratio (OR: 0.97; P < 0.001), and apolipoprotein A1 (OR: 0.56; P = 0.003). The factors that could distinguish between mild/moderate and very severe cases were vascular disorders (OR: 1.59; P < 0.001), HDL (OR: 2.54; P < 0.001), plasma fibrinogen (OR: 1.10; P = 0.012), fructosamine (OR: 1.18; P = 0.001), partial pressure of oxygen (OR: 1.00; P = 0.007), plasma carbon dioxide concentration (OR: 1.01; P < 0.001), standard bicarbonate concentration (OR: 1.13; P < 0.001), partial pressure of carbon dioxide (OR: 1.16; P < 0.001), age (OR: 0.91; P < 0.001), sex (OR: 0.71; P = 0.010), allergic diseases (OR: 0.51; P = 0.009), eosinophil count (OR: 0.42; P = 0.014), lymphocyte ratio (OR: 0.93; P < 0.001), and apolipoprotein A1 (OR: 0.45; P = 0.005). The prediction model correctly predicted disease severity in 60.17% of patients, and kappa coefficient was 0.35 (95% CI: 0.33–0.37).ConclusionThis study developed a prediction model for COPD severity based on biochemical and immunological parameters, which should be validated in additional cohorts.

Dipteris shenzhenensis, a new species of ferns from Shenzhen, Guangdong, southern China, is identified and described. It closely resembles D. chinensis but possesses several unique traits, such as long rhizome scales, castaneous stipe, and abaxially pale fronds with two fan-shaped fronds connected by a broad wing. Molecular evidence showed that D. shenzhenensis is allied to D. conjugata, whereas it has morphologically significant differences (P < 0.05) on the basis of quantitative trait statistical analysis. Overall, the morphological evidence, taken together with the result of cpDNA indicated that D. shenzhenensis is a distinct species.

With the development of open science and technological innovation, using sharing data and molecular biology techniques in the study of taxonomy and systematics have become a crucial component of plants, which undoubtedly helps us discover more hidden outliers or deal with difficult taxa. In this paper, we take Dennstaedtia smithii as an example, based on sharing molecular database, virtual herbarium and plant photo bank, to clarify the outliers that have been hidden in Dennstaedtia and find the key morphological traits with consistent of molecular systematics. In molecular phylogenetic analyses, we used rbcL, rps4, psbA-trnH and trnL-F sequences from 5 new and 49 shared data; the results showed that Dennstaedtia smithii is nested within Microlepia rather than Dennstaedtia. We further studied the morphological characters based on the phylogeny result and found that D. smithii is distinguished from other species of Dennstaedtia by spore ornamentation and the unconnected of grooves between rachis and pinna rachis. According to morphological and molecular phylogenetic studies, our results supported that D. smithii should be a new member of Microlepia and renamed Microlepia smithii (Hook.) Y.H. Yan. Finding hidden outliers can promote the consistency of morphological and molecular phylogenetic results, and make the systematic classification more natural.

Electromagnetic track brake is increasingly applied to improve emergency braking force together with the main wheel-rail brake system, while larger electromagnetic braking force is demanded. The bottom of pole shoe is designed as the same curved surface like track top in order to achieve a good contact between pole shoe and track and the pole shoe chamfering is also designed to improve electromagnetic attractive force. Three main variables that decide the electromagnetic attractive force are selected in the paper: pole shoe contact width, protection block length and pole shoe length. The reliability of electromagnetic simulation is verified through prototype test and then the electromagnetic attractive force in this study is achieved by electromagnetic simulation. First, the effects of the three variables on electromagnetic attractive force are investigated singly. Then, a uniform design method is employed in this study to further optimize electromagnetic attractive force by researching the interactional effects of the three variables. A regression model is established with pole shoe contact width, protection block length and pole shoe length as the independent variables, and electromagnetic attractive force as the dependent variable. Depending on the regression model, the optimum conditions of the three variables are achieved. In addition, finite element simulation of electromagnetic track brake is developed to investigate electromagnetic attractive force and magnetic field distribution by Ansoft Maxwell. Compared to the existing electromagnetic track brake, the electromagnetic braking force and electromagnetic braking deceleration of the optimized electromagnetic track brake are improved by 6.3% under the optimum conditions, which can greatly improve train safety in emergency. The proposed reinforcement optimizations have two outstanding characteristics. The first is keeping the space usage of electromagnetic track brake unaltered, and the other is its simplicity to conduct.

Abstract Background Neuropathic pain is a serious clinical problem that needs to be solved urgently. ASK1 is an upstream protein of p38 and JNK which plays important roles in neuroinflammation during the induction and maintenance of chronic pain. Therefore, inhibition of ASK1 may be a novel therapeutic approach for neuropathic pain. Here, we aim to investigate the effects of paeoniflorin on ASK1 and neuropathic pain. Methods The mechanical and thermal thresholds of rats were measured using the Von Frey test. Cell signaling was assayed using western blotting and immunohistochemistry. Results Chronic constrictive injury (CCI) surgery successfully decreased the mechanical and thermal thresholds of rats and decreased the phosphorylation of ASK1 in the rat spinal cord. ASK1 inhibitor NQDI1 attenuated neuropathic pain and decreased the expression of p-p38 and p-JNK. Paeoniflorin mimicked ASK1 inhibitor NQDI1 and inhibited ASK1 phosphorylation. Paeoniflorin decreased the expression of p-p38 and p-JNK, delayed the progress of neuropathic pain, and attenuated neuropathic pain. Paeoniflorin reduced the response of astrocytes and microglia to injury, decreased the expression of IL-1β and TNF-α, and downregulated the expression of CGRP induced by CCI. Conclusions Paeoniflorin is an effective drug for the treatment of neuropathic pain in rats via inhibiting the phosphorylation of ASK1, suggesting it may be effective in patients with neuropathic pain.

The complete chloroplast genome sequence of Thrixspermum amplexicaule was assembled and analyzed in this work. The total chloroplast genome size of T. amplexicaule was 148,124 bp in length, containing a large single-copy (LSC) region of 86,079 bp, a small single-copy (SSC) region of 10,799 bp, and a pair of inverted repeat (IR) regions of 25,623 bp. The GC content of T. amplexicaule was 36.4%. It encoded a total of 120 unique genes, including 75 protein-coding genes, 37 tRNA genes, and eight rRNA genes. The results of phylogenetic analysis strongly supported that all four samples of Thrixspermum are monophyletic and T. amplexicaule was closely related to T. centipeda.

Because synonymy treatment traditionally relies on morphological judgments, it usually causes many problems in species delimitation and in the biodiversity catalogue. For example, Diplopterygium simulans, which belongs to the Gleicheniaceae family, has been considered to be synonymous with D. glaucum or D. giganteum based mainly on the morphology of its pinna rachis and blade. In the absence of molecular evidence, these revisions remain doubtful. DNA barcoding, which is considered to be a powerful method for species-level identification, was employed to assess the genetic distance among 9 members of the Diplopterygium genus. The results indicate that D. simulans is an independent species rather than a synonymy of D. glaucum or D. giganteum. Moreover, phylogenetic analysis uncovered the sisterhood of D. simulans and D. cantonense, which is supported by their geographical distributions and morphological traits. Incorrect synonymy treatment is prevalent in the characterization of biological diversity, and our study proposes a convenient and effective method for validating synonym treatments and discovering cryptic species.

Building and furniture materials are significant sources of volatile organic compounds (VOCs) and determine their long-time indoor levels. However, the variations of indoor VOCs and associated health risks of interior finishers during the construction stages are poorly understood. In this study, VOCs in the indoor microenvironments were measured at different interior finishing stages at two renovated residences using thermal desorption and gas chromatography-mass spectrometry. The mean concentrations of the Σ15 VOCs were 118.2 μg/m3 in Home A and 232.5 μg/m3 in Home B. The simultaneous outdoor levels were approximately three times lower than indoors. The VOC concentrations were obviously lower than previous measurements in newly renovated residences, reflecting reduced use of these VOCs in interior materials. Temporal variations in the VOC concentrations during the interior finish period were compound- or room-dependent at each residence The remarkable rise in the VOC concentrations was largely affected by furniture installation at both residences. The non-cancer risks of VOC exposure were lower for both interior finishers and occupants. However, the cumulative cancer risks for interior finishers (1.2 × 10−4) exceed the acceptable threshold limit. The occupational exposure at the wall painting stage was the highest, and formaldehyde is the most significant contributor to both cancer and noncancer risks. This study also highlights the importance of detecting novel VOCs that may be present in interior finish materials as indicated by the TVOC measurements.

Introduction: Post-transcriptional RNA modifications are crucial regulators of tumor development and progression. In many biological processes, N1-methyladenosine (m1A) plays a key role. However, little is known about the links between chemical modifications of messenger RNAs (mRNAs) and long noncoding RNAs (lncRNAs) and their function in bladder cancer (BLCA).Methods: Methylated RNA immunoprecipitation sequencing and RNA sequencing were performed to profile mRNA and lncRNA m1A methylation and expression in BLCA cells, with or without stable knockdown of the m1A methyltransferase tRNA methyltransferase 61A (TRMT61A).Results: The analysis of differentially methylated gene sites identified 16,941 peaks, 6,698 mRNAs, and 10,243 lncRNAs in the two groups. Gene ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses of the differentially methylated and expressed transcripts showed that m1A-regulated transcripts were mainly related to protein binding and signaling pathways in cancer. In addition, the differentially genes were identified that were also differentially m1A-modified and identified 14 mRNAs and 19 lncRNAs. Next, these mRNAs and lncRNAs were used to construct a lncRNA-microRNA-mRNA competing endogenous RNA network, which included 118 miRNAs, 15 lncRNAs, and 8 mRNAs. Finally, the m1A-modified transcripts, SCN2B and ENST00000536140, which are highly expressed in BLCA tissues, were associated with decreased overall patient survival.Discussion: This study revealed substantially different amounts and distributions of m1A in BLCA after TRMT61A knockdown and predicted cellular functions in which m1A may be involved, providing evidence that implicates m1A mRNA and lncRNA epitranscriptomic regulation in BLCA tumorigenesis and progression.

Research has been conducted on the exo-glycans. Different methods used for the stereoselective synthesis of these compounds have been investigated and the details are reported.

Abstract. Background:. Hypertension is considered an important risk factor for the coronavirus disease 2019 (COVID-19). The commonly anti-hypertensive drugs are the renin-angiotensin-aldosterone system (RAAS) inhibitors, calcium channel blockers (CCBs), and beta-blockers. The association between commonly used anti-hypertensive medications and the clinical outcome of COVID-19 patients with hypertension has not been well studied. Methods:. We conducted a retrospective cohort study that included all patients admitted with COVID-19 to Huo Shen Shan Hospital and Guanggu District of the Maternal and Child Health Hospital of Hubei Province, Wuhan, China. Clinical and laboratory characteristics were extracted from electronic medical records. Hypertension and anti-hypertensive treatment were confirmed by medical history and clinical records. The primary clinical endpoint was all-cause mortality. Secondary endpoints included the rates of patients in common wards transferred to the intensive care unit and hospital stay duration. Logistic regression was used to explore the risk factors associated with mortality and prognosis. Propensity score matching was used to balance the confounders between different anti-hypertensive treatments. Kaplan-Meier curves were used to compare the cumulative recovery rate. Log-rank tests were performed to test for differences in Kaplan-Meier curves between different groups. Results:. Among 4569 hospitalized patients with COVID-19, 31.7% (1449/4569) had a history of hypertension. There were significant differences in mortality rates between hypertensive patients with CCBs (7/359) and those without (21/359) (1.95% vs. 5.85%, risk ratio [RR]: 0.32, 95% confidence interval [CI]: 0.13–0.76, χ2 = 7.61, P = 0.0058). After matching for confounders, the mortality rates were similar between the RAAS inhibitor (4/236) and non-RAAS inhibitor (9/236) cohorts (1.69% vs. 3.81%, RR: 0.43, 95% CI: 0.13–1.43, χ2 = 1.98, P = 0.1596). Hypertensive patients with beta-blockers (13/340) showed no statistical difference in mortality compared with those without (11/340) (3.82% vs. 3.24%, RR: 1.19, 95% CI: 0.53–2.69, χ2 = 0.17, P = 0.6777). Conclusions:. In our study, we did not find any positive or negative effects of RAAS inhibitors or beta-blockers in COVID-19 patients with hypertension, while CCBs could improve prognosis.

Background: Ferns, originated about 360 million years ago, are the sister group of seed plants. Despite the remarkable progress in our understanding of fern phylogeny, with conflicting molecular evidence and different morphological interpretations, relationships among major fern lineages remain controversial. Results:With the aim to obtain a robust fern phylogeny, we carried out a large-scale phylogenomic analysis using high-quality transcriptome sequencing data, which covered 69 fern species from 38 families and 11 orders. Both coalescent-based and concatenation-based methods were applied to both nucleotide and amino acid sequences in species tree estimation. The resulting topologies are largely congruent with each other, except for the placement of Angiopteris fokiensis, Cheiropleuria bicuspis, Diplaziopsis brunoniana, Matteuccia struthiopteris, Elaphoglossum mcclurei, and Tectaria subpedata. Conclusions: Our result confirmed that Equisetales is sister to the rest of ferns, and Dennstaedtiaceae is sister to eupolypods. Moreover, our result strongly supported some relationships different from the current view of fern phylogeny, including that Marattiaceae may be sister to the monophyletic clade of Psilotaceae and Ophioglossaceae; that Gleicheniaceae and Hymenophyllaceae form a monophyletic clade sister to Dipteridaceae; and that Aspleniaceae is sister to the rest of the groups in eupolypods II. These results were interpreted with morphological traits, especially sporangia characters, and a new evolutionary route of sporangial annulus in ferns was suggested. This backbone phylogeny in ferns sets a foundation for further studies in biology and evolution in ferns, and therefore in plants. [ABSTRACT FROM AUTHOR]

Pharmaceuticals in aquatic environment displayed adverse effects to fish. The effects are usually related to the internal levels of pharmaceuticals accumulated in specific fish tissues. In this study, we investigated the uptake, elimination, and toxicokinetics of six pharmaceuticals, e.g. naproxen (NAX), diclofenac (DCF), ibuprofen (IBU), carbamazepine (CBZ), fluoxetine (FLX), and sertraline (SER), in 11 fish tissues of Nile tilapia. The experiments were conducted in a flow-through system with an 8-day uptake/8-day elimination periods. The fish exposure groups involved the control, single FLX, and mixture of six pharmaceuticals at environmentally relevant concentration of 4 μg/L. FLX and SER showed the maximum concentrations of 145 and 201 ng/g wet weight, respectively, in fish spleen tissue, while NAX and IBU were not detected in any tissue. The mean concentrations for the pharmaceuticals in Nile tilapia tissues generally followed the order: bile> kidney, gut, stomach, liver> brain, gill, spleen> plasma, skin, muscle. The steady-state bioconcentration factors in various tissues generally range at 0.74–437.58 L/kg. The uptake and elimination toxicokinetics illustrated the rapid accumulation and depuration of pharmaceuticals in fish tissues. The results help to understand the internal bioconcentration, tissue distribution, and toxicokinetics of pharmaceuticals in multiple fish biological compartments.

Stepped drift region thickness technique alters the drift region doping dose and its distribution, and therefore modulates the device's off-state characteristics. However, due to the sophisticated structure of the 2-D stepped drift region, the conventional 2-D modeling method is too complicated to provide a clear physical meaning. In this paper, based on the Effective Concentration Profile (ECP) theory, a simple but accurate 1-D ECP concept is proposed to unveil the physical insight of the stepped drift region technique and quantitatively analysis the influence of which on device breakdown characteristic. Therefore, the sophisticated 2-D structure affected by both RESURF and curvature effects is explored by a simple 1-D model with segmented-doped PN junction. Furthermore, based on the proposed analytical model, the designing criterion is proposed, which provide useful guidance for utilizing the benefit of the Stepped Drift Region Thickness technique and thus realizing the optimized surface electric field and breakdown voltage. The results obtained by the proposed model are found to be sufficiently accurate comparing with TCAD simulation results.

The VLT technique features for its irregular thickness of drift region and therefore realize the even surface electric field even with a uniformly doped drift region. However, the sophisticated structure of the drift region also making 2-D methods impractical in both modeling and explaining VLT's physical nature. In this paper, based on the Effective Concentration Profile (ECP) theory, a simple but effective 1-D modeling methodology is proposed to provide physical insight into the VLT technique. The VLT-ECP concept indicates that by physically removing the region that above Charge Appointment Line (CAL), the charge contributes to the lateral depletion can be reduced to zero leading to an even surface electric field. Further, an optimization criterion is proposed to provide useful guidance for the designing of VLT lateral power devices in practice. The comparison between the analytical results obtained by the proposed model and TCAD simulations verified the veracity and effectiveness of the proposed methodology.

The breakdown voltage model of Si-substrated AlGaN/GaN HEMTs with gate and drain field plates is proposed in this work. The silicon substrate and GaN buffer are considered as the depletion region in the modeling process. The analytical model shows great simplicity and veracity. It gives physical insights into the breakdown characteristics of the AlGaN/GaN HEMTs. The avalanche breakdown occurs at the field plate's edge in lateral structure or at the interface in vertical structure. According to the analytical model, the relationship between the lateral breakdown and the vertical breakdown is demonstrated in this work. The breakdown location is affected by the variation of the structure parameters, including gate-to-drain distance, buffer thickness and field plates' lengths. With the aid of the analytical model, effective guidance for device optimization to achieve high performance can be obtained.

This paper proposes a new structure of the negative capacitance field effect transistor (NCFET), which features of the dual ferroelectric region (DFR) when compared to the conventional NCFET. The dual ferroelectric region with FE1 region and FE2 region forms a non-uniform voltage amplification effect, leads to the significantly improvement of the gate control ability and modulates the electric characteristics of the NCFET. The mechanism of the voltage amplification effect, polarization reversal, channel surface electric field, and ferroelectric polarization intensity distributions are investigated. The influences of the ferroelectric parameters α and β on the electric characteristics are discussed. The results show that the DFR-NCFET is able to obtain a subthreshold swing (SS) below the Boltzmann limit (60 mV/dec) by increasing the ferroelectric parameter α of the FE2 region.

The VLD technique has introduced for the propose of achieving the ideal surface electric field via a non-uniformly doped drift region. Yet, the ideal doping profile is impossible to be fulfilled in practical thus breaking the optimized lateral breakdown characteristic. In addition, the conventional 2-D methods, due to its complexity, are impractical in both explaining its physical nature and providing designing guidance. In this paper, a simple 1-D methodology based on Effective Concentration Profile (ECP) theory is proposed to provide the physical insight of the VLD technique and quantitatively depict its breakdown characteristic. The VLD-ECP concept indicates that the perfectly even surface electric field can be obtained by adjusting the drift region doping dose equals to the Charge Appointment Line (CAL) so that all the charges in drift region contribute to the vertical depletion, thus the lateral structure being an equivalently P-I-N junction. Considering non-ideal doping profile of commercial devices, a designing optimization criterion is proposed to avoid the undesirable lateral breakdown. The analytical results obtained by the proposed model are found to be sufficiently accurate comparing with TCAD simulation results verifying the veracity and effectiveness of the proposed methodology.

A novel area-efficient snapback-free silicon-on-insulator lateral insulated gate bipolar transistor (SOI-LIGBT) is proposed and investigated for the first time in this paper. The device features an N+ anode, three separated P+ anodes, and a P-buried layer (PBL) in the N-buffer of the anode region. The N-buffer between all these components above forms a 3-D L-shaped extraction path. The L-shaped extraction path not only makes the device area-efficient but also increases the anode distributed resistance (RSA). Therefore, the snapback effect could be suppressed, and the tradeoff between the on-state voltage (Von) and turn-off energy (Eoff) is improved effectively. Simulation results show that the proposed device eliminates the snapback effect with 63% and 77% reduction of the anode region area compared with the segmented trenches in the anode region (STA) LIGBT and the separated shorted anode (SSA) LIGBT, respectively. At the same Von, the LEP LIGBT reduces the turn-off time (toff) and Eoff by 40% and 28%, respectively, compared with the STA LIGBT. Moreover, at the same Eoff, the LEP LIGBT reduces Von by 17%, compared with the SSA LIGBT.