Biomedical subjects

Bin Yang

Publications and source records attributed to Bin Yang.

At least 19 recordsLinked to original sources

PubMed2026

Screening, optimization and artificial recombination of dsRNA fragments for RNAi-mediated pest resistance in Apolygus lucorum.

RNA interference (RNAi) is an eco-friendly strategy for pest management, with double-stranded RNA (dsRNA) as the core functional component. In this study, three RNAi target genes (Ubx, wupA and Dpp) with strong lethal effects on Apolygus lucorum were screened via microinjection. The 7-day cumulative mortalities were 56.67 ± 3.33% for dsUbx, 94.44 ± 1.11% for dswupA and 92.22 ± 1.11% for dsDpp. We optimized dsRNA sequences by removing conserved sequences in non-target organisms based on homology alignment and off-target risk analysis. The optimized fragments dswupA-OTE and dsDpp-OTE still exhibited high insecticidal activity, with 7-day cumulative mortalities of 77.78 ± 2.94% and 70.00 ± 1.93%, respectively. We also evaluated the effects of dsRNA length and target sites on RNAi efficiency and screened potent short dsRNA fragments. Novel artificially recombinant dsRNAs were constructed by assembling effective short fragments from different genes, which retained strong insecticidal activity despite shorter sequence length. This study verifies the feasibility of multi-target recombinant dsRNA for pest control and provides a theoretical basis for developing multi-gene RNAi technologies against A. lucorum.

Apolygus lucorum↗

PubMed2026

Structural and functional characterization of peanut expansin proteins identifies AhEXPA3 as a stress-responsive regulator of seed germination.

Expansins are cell wall-associated proteins that play important roles in plant growth, development, and environmental responses, yet their structural features and functional significance in peanut remain insufficiently understood. Here, we performed a genome-wide identification and characterization of 70 expansin proteins in cultivated peanut. Phylogenetic analysis classified these genes into four subfamilies (EXPA, EXPB, EXLA, and EXLB), with conserved motif patterns and subgroup-specific exon-intron structures. Collinearity and evolutionary analyses revealed that segmental duplication mainly drove peanut expansin family expansion, with most duplicated gene pairs subsequently undergoing purifying selection. Promoter analysis identified abundant cis-regulatory elements associated with light responses, hormone signaling, and stress responses. Expression profiling indicated that many AhEXP genes were differentially expressed during seed germination and in response to abscisic acid (ABA), salt, and osmotic stresses. Among them, AhEXPA3 was identified as a stress-responsive expansin protein with marked transcriptional induction under abiotic stress conditions. Subcellular localization analysis suggested that AhEXPA3 exhibits an endoplasmic reticulum-associated localization pattern. Functional assays further demonstrated that heterologous expression of AhEXPA3 inhibited seed germination and early seedling establishment under stress conditions in both Arabidopsis thaliana and rice. These findings support a negative regulatory role of AhEXPA3 in stress-responsive seed germination and broaden current understanding of expansin protein function in legumes.

Germination↗

PubMed2026

Acupuncture improves depressive symptoms and prefrontal cortical function in mild to moderate depressive disorder: A randomized sham-controlled trial and fNIRS study.

BACKGROUND: Depressive disorder is a common mental illness associated with substantial functional impairment. Although pharmacotherapy is widely used, its effectiveness is often limited by adverse effects and poor adherence. Acupuncture has been increasingly applied as a complementary treatment for depression, and its neurobiological characteristics remain unclear. OBJECTIVE: This randomized, sham-controlled trial aimed to evaluate the clinical efficacy of acupuncture for mild to moderate depressive disorder and to investigate its effects on prefrontal cortical function using functional near-infrared spectroscopy (fNIRS). METHODS: Patients with mild to moderate depressive disorder were randomly assigned to a real acupuncture (RA) group or a sham acupuncture (SA) group and received standardized treatment for 8 weeks. Clinical outcomes were assessed using the Self-Rating Depression Scale (SDS), Self-Rating Anxiety Scale (SAS), Short Form-36 Health Survey (SF-36), and a traditional Chinese medicine syndrome score. A subset of participants underwent fNIRS assessment during resting-state and task-based conditions to evaluate prefrontal cortical activation and functional connectivity. RESULTS: Compared with baseline, the RA group showed significant reductions in SDS and SAS scores and significant improvements in SF-36 emotional domains, with effects emerging at Week 4 and persisting up to 12 weeks after treatment. Improvements were greater and more stable in the RA group than in the SA group. fNIRS analyses revealed enhanced activation in dorsolateral and medial prefrontal regions and strengthened prefrontal functional connectivity following acupuncture, whereas neural changes in the SA group were limited. CONCLUSION: Acupuncture is effective for improving depressive and anxiety symptoms and quality of life in patients with mild to moderate depressive disorder. Modulation of prefrontal cortical activation and connectivity may underlie its antidepressant effects.

Humans↗

PubMed2026

Exploring Causal Links Between 91 Circulating Inflammatory Proteins and Hashimoto's Thyroiditis: A Bidirectional Mendelian Randomization Study.

BACKGROUND: Increasing evidence has linked inflammation to Hashimoto's thyroiditis (HT) etiology. However, the causal role of circulating inflammatory proteins in HT remains uncertain. To investigate this, we conducted a bidirectional Mendelian randomization (MR) study. METHODS: Genetic data for 91 inflammatory proteins and HT were sourced from publicly available GWAS databases. The PhenoScanner database was then searched for pleiotropic SNPs associated with potential confounders. Inverse variance weighted (IVW) analysis was used as the primary analysis, simultaneously supplemented by five sensitivity analyses to strengthen the results. RESULTS: The results revealed that, after false discovery rate (FDR) correction, interleukin (IL)-12p40 was causally associated with increased risk of HT (OR [95% CI] = 1.295 [1.172, 1.431], p = 3.66 × 10-7, PFDR = 3.33×10-5). Conversely, none of the inflammatory proteins was a consequence of HT. CONCLUSION: This study suggests that IL-12p40 is probably one of the factors correlated with HT etiology, contributing to a better understanding of the pathogenesis of HT and underscoring the potential for therapeutic interventions targeting inflammatory proteins.

Humans↗

PubMed2026

Transmission history of major China-prevalent Mycobacterium tuberculosis sub-lineages in East Asia.

Mycobacterium tuberculosis complex (MTBC) is distributed globally and has posed a severe threat to human health throughout history. In this study, we analyzed whole-genome data from the four major MTBC sub-lineages prevalent in China (L2.2, L4.2, L4.4, and L4.5) to reconstruct their transmission and expansion histories across East Asia and parts of Central Asia. We found that L2.2 has established a highly connected transmission network centered in Southern China, whereas L4.2 is characterized by cross-border transmission between Central Asia and Western China, and L4.4 and L4.5 exhibit repeated transmission events between Southeast Asia and Southern China. By reconstructing their population histories, we demonstrated that these sub-lineages have experienced multi-stage expansions since the 15th century, accompanied by a recent rapid proliferation of evolutionary clades. These findings reveal that the MTBC epidemic in East Asia may follow a pattern of long-term historical adaptation superimposed with recent concentrated outbreaks, providing potential genomic evidence to inform precise regional tuberculosis control strategies in China.

Mycobacterium tuberculosis↗

PubMed2024

Integrative Multi-PTM Proteomics Reveals Dynamic Global, Redox, Phosphorylation, and Acetylation Regulation in Cytokine-Treated Pancreatic Beta Cells.

Studying regulation of protein function at a systems level necessitates an understanding of the interplay among diverse posttranslational modifications (PTMs). A variety of proteomics sample processing workflows are currently used to study specific PTMs but rarely characterize multiple types of PTMs from the same sample inputs. Method incompatibilities and laborious sample preparation steps complicate large-scale physiological investigations and can lead to variations in results. The single-pot, solid-phase-enhanced sample preparation (SP3) method for sample cleanup is compatible with different lysis buffers and amenable to automation, making it attractive for high-throughput multi-PTM profiling. Herein, we describe an integrative SP3 workflow for multiplexed quantification of protein abundance, cysteine thiol oxidation, phosphorylation, and acetylation. The broad applicability of this approach is demonstrated using cell and tissue samples, and its utility for studying interacting regulatory networks is highlighted in a time-course experiment of cytokine-treated β-cells. We observed a swift response in the global regulation of protein abundances consistent with rapid activation of JAK-STAT and NF-κB signaling pathways. Regulators of these pathways as well as proteins involved in their target processes displayed multi-PTM dynamics indicative of complex cellular response stages: acute, adaptation, and chronic (prolonged stress). PARP14, a negative regulator of JAK-STAT, had multiple colocalized PTMs that may be involved in intraprotein regulatory crosstalk. Our workflow provides a high-throughput platform that can profile multi-PTMomes from the same sample set, which is valuable in unraveling the functional roles of PTMs and their co-regulation.

Proteomics↗

PubMed2007

Influence of contamination on bonding to zirconia ceramic.

The purpose of this study was to investigate the influences of contaminations and cleaning methods on bonding to dental zirconia ceramic. After saliva immersion and using silicone disclosing agent, airborne-particle abraded ceramic specimens were cleaned with isopropanol (AL), acetone (AC), 37% phosphoric acid (PA), additional airborne-particle abrasion (AA), or only with water rinsing (SS). Airborne-particle abraded specimens without contaminations (CL) were used as control group. For chemical analysis specimens of all groups were examined with X-ray photoelectron spectroscopy (XPS). Plexiglas tubes filled with composite resin were bonded to ceramic specimens using a phosphate-monomer containing composite luting resin. After 3-day water storage, tensile bond strengths (TBS) were tested. XPS analysis of group SS showed the presence of saliva and silicone (Si) contamination on the surface. The ratios of carbon/zirconium and oxygen/zirconium for groups PA and AA were comparable to those ratios obtained for group CL, indicating the removal of the organic saliva contamination. Airborne-particle abrasion and acetone completely removed Si contamination from ceramic surfaces. Isopropanol had little cleaning effect on the two contaminants. TBS (median +/- standard deviation) in MPa of the groups SS (11.6 +/- 3.1), AL (10.0 +/- 2.9), and AC (13.0 +/- 2.8) were statistically lower than those of groups PA (33.6 +/- 5.5), AA (40.1 +/- 3.6), and CL (47.0 +/- 8.1) (p < 0.001), while no differences were found in TBS between groups AA and CL (p > 0.5). Contamination significantly reduced bond strengths to zirconia ceramic. Airborne-particle abrasion was the most effective cleaning method.

Ceramics↗

PubMed2007

Tropane alkaloids production in transgenic Hyoscyamus niger hairy root cultures over-expressing putrescine N-methyltransferase is methyl jasmonate-dependent.

The cDNA from Nicotiana tabacum encoding Putrescine N-methyltransferase (PMT), which catalyzes the first committed step in the biosynthesis of tropane alkaloids, has been introduced into the genome of a scopolamine-producing Hyoscyamus niger mediated by the disarmed Agrobacterium tumefaciens strain C58C1, which also carries Agrobacterium rhizogenes Ri plasmid pRiA4, and expressed under the control of the CaMV 35S promoter. Hairy root lines transformed with pmt presented fivefold higher PMT activity than the control, and the methylputrescine (MPUT) levels of the resulting engineered hairy roots increased four to fivefold compared to the control and wild-type roots, but there was no significant increase in tropane alkaloids. However, after methyl jasmonate (MeJA) treatment, a considerable increase of PMTase and endogenous H6Hase as well as an increase in scopolamine content was found either in the transgenic hairy roots or the control. The results indicate that hairy root lines over-expressing pmt have a high capacity to synthesize MPUT, whereas their ability to convert hyoscyamine into scopolamine is very limited. Exposure to MeJA strongly stimulated both polyamine and tropane biosynthesis pathways and elicitation led to more or less enhanced production simultaneously.

Acetates↗

PubMed2006

Effect of acid on the aggregation of poly(ethylene xide)-poly(propylene oxide)-poly(ethylene oxide) block copolymers.

The acid effect on the aggregation of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymers EO(20)PO(70)EO(20) has been investigated by transmission electron microscopy (TEM), particle size analyzer (PSA), Fourier transformed infrared, and fluorescence spectroscopy. The critical micellization temperature for Pluronic P123 in different HCl aqueous solutions increases with the increase of acid concentration. Additionally, the hydrolysis degradation of PEO blocks is observed in strong acid concentrations at higher temperatures. When the acid concentration is low, TEM and PSA show the increase of the micelle mean diameter and the decrease of the micelle polydispersity at room temperature, which demonstrate the extension of EO corona and tendency of uniform micelle size because of the charge repulsion. When under strong acid conditions, the aggregation of micelles through the protonated water bridges was observed.

Epoxy Compounds↗

PubMed2006

[Difference analysis on proteome of Helicobacter pylori in patients with peptic ulcer, gastritis, and gastric cancer].

OBJECTIVE: To identify the different proteins of Helicobacter pylori (H. pylori) in gastric cancer, peptic ulcer, and gastritis initially. METHODS: H. pylori in the endoscopic biopsy specimens of gastric mucosa of patients with gastric cancer, peptic ulcer, or gastritis, 3 specimens for each disease, were separated and cultured. The whole-cell protein of the H. pylori was extracted by lysis buffer and sonication. The protein concentration of the bacteria cell lysates was measured by the Bradford method. The protein maps of H. pylori were obtained by two-dimensional gel electrophoresis (2-DE) and the different proteins in gastric cancer, peptic ulcer and gastritis were analyzed by Image Master v 5.0. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-Q-TOF-MS) were performed to identify the different proteins. The differential proteins were searched by the Mascot database at www.matrixscience.com. RESULTS: Four protein spots of H. pylori were over-expressed in the protein maps from gastric cancer in comparison with those from peptic ulcer and gastritis. Mass identification showed that the 4 proteins were thioredoxin, adenylate kinase, single-stranded DNA-binding protein, and ribosomal protein 50S L7/L12, with the Mowse scores of 94, 286, 139 and 132, and with the sequence coverage rates of 77%, 33%, 33%, and 28% respectively. CONCLUSION: Anti-oxidant and inhibiting apoptosis, thioredoxin may be related to gastric carcinogenesis induced by H. pylori. Proteomics technology has a widespread perspective in the field of relationship between pathogenic bacteria and gastric cancer.

Adult↗

PubMed2006

Changes in the enzymatic hydrolysis rate of Avicel cellulose with conversion.

The slow down in enzymatic hydrolysis of cellulose with conversion has often been attributed to declining reactivity of the substrate as the more easily reacted material is thought to be consumed preferentially. To better understand the cause of this phenomenon, the enzymatic reaction of the nearly pure cellulose in Avicel was interrupted over the course of nearly complete hydrolysis. Then, the solids were treated with proteinase to degrade the cellulase enzymes remaining on the solid surface, followed by proteinase inhibitors to inactive the proteinase and successive washing with water, 1.0 M NaCl solution, and water. Next, fresh cellulase and buffer were added to the solids to restart hydrolysis. The rate of cellulose hydrolysis, expressed as a percent of substrate remaining at that time, was approximately constant over a wide range of conversions for restart experiments but declined continually with conversion for uninterrupted hydrolysis. Furthermore, the cellulose hydrolysis rate per adsorbed enzyme was approximately constant for the restart procedure but declined with conversion when enzymes were left to react. Thus, the drop off in reaction rate for uninterrupted cellulose digestion by enzymes could not be attributed to changes in substrate reactivity, suggesting that other effects such as enzymes getting "stuck" or otherwise slowing down may be responsible.

Cellulase↗

PubMed2006

Vacuum ultraviolet photoionization mass spectrometric study of ethylenediamine.

The photoionization and dissociative photoionizations of ethylenediamine have been studied both experimentally and theoretically. In experiments, photoionization efficiency spectra for ions NH(2)CHCH(3)(+), NH(2)CH=CH(2)(+), CH(2)NH(2)(+), NH(3)(+), NH(2)CH(2)CHNH(2)(+) and NH(2)CH(2)CH(2)NH(2)(+) have been obtained. In addition, the energetics of the dissociative photoionization is investigated with ab initio Gaussian-3 (G3) calculations. The computational results are useful in analyzing the dissociation channels near the ionization thresholds. With the help of the G3 results, the dissociation channels for the formation of the aforementioned fragment ions have been established.

Journal Article↗

PubMed2006

BSA treatment to enhance enzymatic hydrolysis of cellulose in lignin containing substrates.

Cellulase and bovine serum albumin (BSA) were added to Avicel cellulose and solids containing 56% cellulose and 28% lignin from dilute sulfuric acid pretreatment of corn stover. Little BSA was adsorbed on Avicel cellulose, while pretreated corn stover solids adsorbed considerable amounts of this protein. On the other hand, cellulase was highly adsorbed on both substrates. Adding a 1% concentration of BSA to dilute acid pretreated corn stover prior to enzyme addition at 15 FPU/g cellulose enhanced filter paper activity in solution by about a factor of 2 and beta-glucosidase activity in solution by about a factor of 14. Overall, these results suggested that BSA treatment reduced adsorption of cellulase and particularly beta-glucosidase on lignin. Of particular note, BSA treatment of pretreated corn stover solids prior to enzymatic hydrolysis increased 72 h glucose yields from about 82% to about 92% at a cellulase loading of 15 FPU/g cellulose or achieved about the same yield at a loading of 7.5 FPU/g cellulose. Similar improvements were also observed for enzymatic hydrolysis of ammonia fiber explosion (AFEX) pretreated corn stover and Douglas fir treated by SO(2) steam explosion and for simultaneous saccharification and fermentation (SSF) of BSA pretreated corn stover. In addition, BSA treatment prior to hydrolysis reduced the need for beta-glucosidase supplementation of SSF. The results are consistent with non-specific competitive, irreversible adsorption of BSA on lignin and identify promising strategies to reduce enzyme requirements for cellulose hydrolysis.

Adsorption↗

PubMed2006

Apoptosis and caspase-3 in long-term renal ischemia/reperfusion injury in rats and divergent effects of immunosuppressants.

BACKGROUND: Caspase-3 plays a key role in apoptosis, but the involvement of apoptosis and caspase-3 in mediating long-term ischemia/reperfusion (I/R) and immunosuppressive injury are not fully defined. The present study was undertaken to investigate apoptosis and caspase-3 in a renal I/R injury rat model with or without immunosuppression. METHODS: The right renal pedicle was clamped for 45 minutes and left nephrectomy was induced. Cyclosporin A (CsA), tacrolimus (Tac), rapamycin (Rap), or mycophenolate mofetil (MMF) were administered daily. Animals were killed at 16 weeks, and the levels of apoptosis (with in situ end-labeling fragmented DNA), caspase-3 protein (with immunohistochemistry, Western blotting, and activity assay), and messenger RNA (mRNA; with quantitative reverse-transcriptase polymerase chain reaction) were evaluated. RESULTS: Kidneys with I/R injury showed increased apoptosis in tubular and interstitial areas compared with control kidneys. Tacrolimus, Rap, and MMF significantly reduced apoptosis, but CsA did not. Distribution of full-length caspase-3 widened in I/R-injured kidneys from normal distal tubules and collecting ducts to dilated proximal tubules and expanded interstitium, whereas active caspase-3 was mainly scattered in damaged tubules and interstitium. Active caspase-3 staining and 24-kDa active caspase-3 protein was enhanced in I/R-injured and CsA-treated kidneys, but decreased by Tac, Rap, and MMF. These results were also consistent with changes in caspase-3 activity. Although caspase-3 mRNA levels were significantly increased in uninephrectomy and I/R-injured kidneys, they were not significantly affected by the immunosuppressants. In addition, all changes detected were positively correlated with renal structure and function. CONCLUSION: Apoptosis and caspase-3 are not only involved in the long-term renal I/R injury, but also mediate the divergent effects of immunosuppression in this model.

Animals↗

PubMed2006

[Evaluation of the efficacy of phenobarbital in treatment of epilepsy in rural areas: study of 2455 patients in rural China].

OBJECTIVE: To evaluate the efficacy of phenobarbital in treatment of patients with convulsive forms of epilepsy in rural areas and to develop a suitable relevant model for rural China. METHODS: A demonstration protocol was conducted in the rural areas of 8 counties from 6 provinces and municipality in China, Heilongjiang, Ningxia, Henan, Jiangsu, Shanxi, and Shanghai from December 2001 to June 2004. Epidemiological investigation of the prevalence and treatment gap of epilepsy was carried out. Patients with convulsive forms of epilepsy thus screened underwent treatment of phenobarbital. Physicians of township hospitals received short-term training to be in charge of the treatment and regular follow-up of the patients. RESULTS: A total of 2455 patients with generalized tonic-clonic seizures in these 6 rural areas were screened and entered the treatment group. 347 patients (26.2%) had been seizure-free during the period of these 2 years, 415 patients (31.3%) had their seizure frequencies decreased by > 75% as compared with those during the period of 6 months before treatment, and the conditions of 26.1% of the patients did not change or even became worse. About 26.1% of the patients had mild side effects, 3.7% had moderate side effects, and only 0.3% had severe side effects when the dosage of phenobarbital in the first 3 months was increased. 597 patients (24.3%) withdrew from the treatment group because of various reasons. CONCLUSION: This protocol was suitable to the rural areas of China. The trained physicians are capable of fulfilling the task to treat the patients with epilepsy. Phenobarbital is an effective drug for most patients with convulsive seizures and has no severe side effect.

Adolescent↗

PubMed2006

Experimental quantum communication without a shared reference frame.

We present an experimental realization of a robust quantum communication scheme [Phys. Rev. Lett. 93, 220501 (2004)] using pairs of photons entangled in polarization and time. Our method overcomes errors due to collective rotation of the polarization modes (e.g., birefringence in optical fiber or misalignment), is insensitive to the phase's fluctuation of the interferometer, and does not require any shared reference frame including time reference, except the need to label different photons. The practical robustness of the scheme is further shown by implementing a variation of the Bennett-Brassard 1984 quantum key distribution protocol over 1 km optical fiber.

Journal Article↗

PubMed2006

Quantitative analysis of promoter hypermethylation in multiple genes in osteosarcoma.

BACKGROUND: Osteosarcoma is the most common solid malignant diseases of childhood, occurring in approximately 6 children per million annually; however, to the authors' knowledge to date, the cause of osteosarcoma has remained mostly unknown. Genetic alterations of genes that are specific for osteosarcoma have not been identified. Genetic alternations in the status of DNA methylation, known as epigenetic alterations, are the most common molecular alterations in human neoplasia. Aberrant methylation in the promoter region of tumor-related genes is associated closely with epigenetically mediated gene silencing, which is a common feature in human tumors. METHODS: The authors analyzed CpG islands of 5 different gene loci for aberrant methylation profiles in 30 pairs of osteosarcoma and corresponding normal tissues by using the quantitative methylation-specific polymerase chain reaction method. The objectives of this study were to characterize the methylation changes in osteosarcoma more extensively and to identify epigenetic biomarkers that may be useful in the diagnosis and prevention of osteosarcoma. RESULTS: For the Ras effector homologue (RASSF1A), tissue inhibitor of metalloproteinase 3 (TIMP3), O-6-methylguanine DNA methyltransferase (MGMT), and death-associated protein kinase 1 (DAPK1) genes, significant differences were observed in the degree of hypermethylation between tumors and normal tissues (P < 0.01 and P < 0.001, respectively). Measurement of the cumulative multiple promoter hypermethylation revealed striking differences between tumor specimens and normal tissues (t = 7.31; P < .001). There also was a significant difference in the levels of DNA methylation between the metastatic and nonmetastatic high-grade osteosarcomas (t = 4.57; P < .01). In addition, the methylation levels were associated closely with gender (t = 6.44; P < .001). CONCLUSIONS: The results indicated that tumor tissues from patients with osteosarcoma had a significantly higher incidence of hypermethylation for several genes compared with corresponding normal tissues. The epigenetic changes observed in this study may have prognostic importance for patients with osteosarcoma.

Adolescent↗

PubMed2006

Identification and chemistry of C4H3 and C4H5 isomers in fuel-rich flames.

Quantitative identification of isomers of hydrocarbon radicals in flames is critical to understanding soot formation. Isomers of C4H3 and C4H5 in flames fueled by allene, propyne, cyclopentene, or benzene are identified by comparison of the observed photoionization efficiencies with theoretical simulations based on calculated ionization energies and Franck-Condon factors. The experiments combine molecular-beam mass spectrometry (MBMS) with photoionization by tunable vacuum-ultraviolet synchrotron radiation. The theoretical simulations employ the rovibrational properties obtained with B3LYP/6-311++G(d,p) density functional theory and electronic energies obtained from QCISD(T) ab initio calculations extrapolated to the complete basis set limit. For C4H3, the comparisons reveal the presence of the resonantly stabilized CH2CCCH isomer (i-C4H3). For C4H5, contributions from the CH2CHCCH2 (i-C4H5) and some combination of the CH3CCCH2 and CH3CHCCH isomers are evident. Quantitative concentration estimates for these species are made for allene, cyclopentene, and benzene flames. Because of low Franck-Condon factors, sensitivity to n-isomers of both C4H3 and C4H5 is limited. Adiabatic ionization energies, as obtained from fits of the theoretical predictions to the experimental photoionization efficiency curves, are within the error bars of the QCISD(T) calculations. For i-C4H3 and i-C4H5, these fitted adiabatic ionization energies are (8.06 +/- 0.05) eV and (7.60 +/- 0.05) eV, respectively. The good agreement between the fitted and theoretical ionization thresholds suggests that the corresponding theoretically predicted radical heats of formation (119.1, 76.3, 78.7, and 79.1 kcal/mol at 0 K for i-C4H3, i-C4H5, CH3CCCH2, and CH3CHCCH, respectively) are also quite accurate.

Carbon Compounds, Inorganic↗