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1.
Int J Biol Macromol ; 265(Pt 2): 130850, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38492706

ABSTRACT

Recent decades have witnessed a surge in research interest in bio-nanocomposite-based packaging materials, but still, a lack of systematic analysis exists in this domain. Bio-based packaging materials pose a sustainable alternative to petroleum-based packaging materials. The current work employs bibliometric analysis to deliver a comprehensive outline on the role of bio nanocomposites in packaging. India, Iran, and China were revealed to be the top three nations actively engaged in this domain in total publications. Islamic Azad University in Iran and Universiti Putra Malaysia in Malaysia are among the world's best institutions in active research and publications in this field. The extensive collaboration between nations and institutions highlights the significance of a holistic approach towards bio-nanocomposite. The National Natural Science Foundation of China is the leading funding body in this field of research. Among authors, Jong whan Rhim secured the topmost citations (2234) in this domain (13 publications). Among journals, Carbohydrate Polymers secured the maximum citation count (4629) from 36 articles; the initial one was published in 2011. Bio nanocomposite is the most frequently used keyword. Researchers and policymakers focussing on sustainable packaging solutions will gain crucial insights on the current research status on packaging solutions using bio-nanocomposites from the conclusions.


Subject(s)
Bibliometrics , Nanocomposites , Humans , Publications , Product Packaging , Data Mining
2.
Org Lett ; 26(9): 1851-1856, 2024 Mar 08.
Article in English | MEDLINE | ID: mdl-38386702

ABSTRACT

Enamine and iminium ion-mediated asymmetric organocatalysis was not successful in achieving highly stereoselective α-chlorination of acyclic α,α-disubstituted carbonyls. To address this limitation, an alternative method was developed, which involved the use of geometry-defined persubstituted enesulfinamides to intercept the electrophilic chlorinating reagent. This approach enables the asymmetric construction of challenging acyclic α,α-disubstituted α-chlorinated ketimines with a high degree of stereoselectivity. The use of chloramine-T, a cost-effective and stable chlorine source rarely utilized in asymmetric electrophilic chlorination, plays a crucial role in achieving superior stereocontrol.

3.
Brief Bioinform ; 24(2)2023 03 19.
Article in English | MEDLINE | ID: mdl-36892171

ABSTRACT

The adaptive immune receptor repertoire (AIRR), consisting of T- and B-cell receptors, is the core component of the immune system. The AIRR sequencing is commonly used in cancer immunotherapy and minimal residual disease (MRD) detection of leukemia and lymphoma. The AIRR is captured by primers and sequenced to yield paired-end (PE) reads. The PE reads could be merged into one sequence by the overlapped region between them. However, the wide range of AIRR data raises the difficulty, so a special tool is required. We developed a software package for IMmune PE reads merger of sequencing data, named IMperm. We used the k-mer-and-vote strategy to pin down the overlapped region rapidly. IMperm could handle all types of PE reads, eliminate adapter contamination and successfully merge low-quality and minor/non-overlapping reads. Compared with existing tools, IMperm performed better in both simulated and sequencing data. Notably, IMperm was well suited to processing the data of MRD detection in leukemia and lymphoma and detected 19 novel MRD clones in 14 patients with leukemia from previously published data. Additionally, IMperm can handle PE reads from other sources, and we demonstrated its effectiveness on two genomic and one cell-free deoxyribonucleic acid datasets. IMperm is implemented in the C programming language and consumes little runtime and memory. It is freely available at https://github.com/zhangwei2015/IMperm.


Subject(s)
Genomics , High-Throughput Nucleotide Sequencing , Humans , Sequence Analysis, DNA , Software , Genome , Algorithms
4.
Front Psychol ; 13: 809314, 2022.
Article in English | MEDLINE | ID: mdl-35432101

ABSTRACT

The evaluation of tourism competitiveness is an important tool for analyzing the potential of tourism in a specific context. Enshi Autonomous Prefecture (EAP) in China is selected as a case through which to explore the potential of mountain tourism and its competitiveness in the tourism industry. This study develops EAP's mountain tourism competitiveness model focusing on three criteria: core competitiveness of mountain tourism, the economic environment's competitiveness, and infrastructure competitiveness. Context-specific customized evaluation index has been applied to data collected from EAP Statistical Yearbook for 2005-2014. The study reveals that the value of EAP's mountain tourism core competitiveness, economic and environmental competitiveness, and infrastructure competitiveness are 84.292, 13.4, and 2.308%, respectively. When tourism core competitiveness is increased by one unit, EAP's mountain tourism competitiveness will increase by 0.84292 units. Similarly, when economic environment competitiveness is increased by one unit, EAP's mountain tourism competitiveness will increase by 0.134 units. EAP's mountain tourism competitiveness increases by 0.02308 units when infrastructure competitiveness increases by one unit. The major reasons for low levels of competitiveness were lack of awareness of the county authority, a low level of cooperation, and weak infrastructure. The recommendations from the study's findings are as follows. Firstly, the county authority should appropriately improve the relationship between competition and cooperation, maintaining cooperation in competition, and competition in cooperation. Secondly, the county authority should strengthen communication by establishing an effective coordinated mechanism. Thirdly, the county authority should improve the sense of cooperation and jointly develop the mountain tourism market. Fourthly, the county authority should improve the construction of tourism infrastructure and break down the barriers to tourism cooperation. The study's findings help develop a "win-win" cooperation mechanism within the competition and support the sustainable development of the mountain tourism industry while reducing poverty and promoting the revitalization of the mountains of China.

5.
Sci Total Environ ; 827: 154341, 2022 Jun 25.
Article in English | MEDLINE | ID: mdl-35257765

ABSTRACT

The addition of thermally conductive nanomaterials is an effective strategy for increasing the thermal conductivity of phase change materials (PCMs). However, nanomaterials are expensive and may significantly reduce the latent heat capacity of PCMs. In this study, low-cost and eco-friendly biochar microparticles were prepared from garlic stems, a common food waste in Singapore. The thermal properties of paraffin wax (PW) doped with 1, 3, and 5 wt% garlic stem biochar (GSB) microparticles were investigated. The GSB microparticles prepared at 700 °C had three-dimensional porous and two-dimensional flake-like structures, which contributed to the formation of additional heat transfer pathways in the PW. The addition of 5 wt% GSB microparticles enhanced the thermal conductivity of PW by 27.3% and 7.2% in the solid and liquid phases, respectively. The T-history test revealed that the melting and solidification rates of PW improved by 90 and 115 s, respectively. The improved heat transfer performance was mainly ascribed to the high degree of graphitization and the interconnected porous carbon structure of the GSB microparticles. The phase change temperatures of PW were slightly changed upon the addition of GSB microparticles, and the latent heat capacity was only reduced by 6.1%. These results suggest that the GSB microparticles can be used as a potential alternative to other nanoadditives such as metal- and metal oxide-based nanoadditives.


Subject(s)
Garlic , Refuse Disposal , Charcoal , Food , Paraffin , Thermal Conductivity
6.
ISME J ; 16(4): 983-996, 2022 04.
Article in English | MEDLINE | ID: mdl-34750528

ABSTRACT

Irritable bowel syndrome (IBS) is one of the functional gastrointestinal disorders characterized by chronic and/or recurrent symptoms of abdominal pain and irregular defecation. Changed gut microbiota has been proposed to mediate IBS; however, contradictory results exist, and IBS-specific microbiota, metabolites, and their interactions remain poorly understood. To address this issue, we performed metabolomic and metagenomic profiling of stool and serum samples based on discovery (n = 330) and validation (n = 101) cohorts. Fecal metagenomic data showed moderate dysbiosis compared with other diseases, in contrast, serum metabolites showed significant differences with greater power to distinguish IBS patients from healthy controls. Specifically, 726 differentially abundant serum metabolites were identified, including a cluster of fatty acyl-CoAs enriched in IBS. We further identified 522 robust associations between differentially abundant gut bacteria and fecal metabolites, of which three species including Odoribacter splanchnicus, Escherichia coli, and Ruminococcus gnavus were strongly associated with the low abundance of dihydropteroic acid. Moreover, dysregulated tryptophan/serotonin metabolism was found to be correlated with the severity of IBS depression in both fecal and serum metabolomes, characterized by a shift in tryptophan metabolism towards kynurenine production. Collectively, our study revealed serum/fecal metabolome alterations and their relationship with gut microbiome, highlighted the massive alterations of serum metabolites, which empower to recognize IBS patients, suggested potential roles of metabolic dysregulation in IBS pathogenesis, and offered new clues to understand IBS depression comorbidity. Our study provided a valuable resource for future studies, and would facilitate potential clinical applications of IBS featured microbiota and/or metabolites.


Subject(s)
Irritable Bowel Syndrome , Microbiota , Comorbidity , Depression , Feces/microbiology , Humans , Irritable Bowel Syndrome/complications , Irritable Bowel Syndrome/diagnosis , Irritable Bowel Syndrome/metabolism , Metabolome , Tryptophan/metabolism
7.
Zool Res ; 41(4): 437-443, 2020 Jul 18.
Article in English | MEDLINE | ID: mdl-32400976

ABSTRACT

Sleep is indispensable for human health, with sleep disorders initiating a cascade of negative consequences. As our closest phylogenetic relatives, non-human primates (NHPs) are invaluable for comparative sleep studies and exhibit tremendous potential for improving our understanding of human sleep and related disorders. Previous work on measuring sleep in NHPs has mostly used electroencephalography or videography. In this study, simultaneous videography and actigraphy were applied to observe sleep patterns in 10 cynomolgus monkeys ( Macaca fascicularis) over seven nights (12 h per night). The durations of wake, transitional sleep, and relaxed sleep were scored by analysis of animal behaviors from videography and actigraphy data, using the same behavioral criteria for each state, with findings then compared. Here, results indicated that actigraphy constituted a reliable approach for scoring the state of sleep in monkeys and showed a significant correlation with that scored by videography. Epoch-by-epoch analysis further indicated that actigraphy was more suitable for scoring the state of relaxed sleep, correctly identifying 97.57% of relaxed sleep in comparison with video analysis. Only 34 epochs (0.13%) and 611 epochs (2.30%) were differently interpreted as wake and transitional sleep compared with videography analysis. The present study validated the behavioral criteria and actigraphy methodology for scoring sleep, which can be considered as a useful and a complementary technique to electroencephalography and/or videography analysis for sleep studies in NHPs.


Subject(s)
Haplorhini/physiology , Sleep , Video Recording/methods , Actigraphy/methods , Actigraphy/veterinary , Animals
8.
Journal of Chinese Physician ; (12): 331-336, 2020.
Article in Chinese | WPRIM (Western Pacific) | ID: wpr-867246

ABSTRACT

Laparoscopic anatomical hepatectomy of hepatic vein approach is a laparoscopic hepatectomy technique based on anatomical hepatectomy and guided by hepatic vein. It not only can completely remove the focus and retain the structural integrity of the remaining liver tissue, but also has the advantages of less trauma and rapid recovery by laparoscopy. When the transection plane is guided by complete exposure of hepatic vein, the ineffective liver tissue without inflow and outflow tract can be completely removed, the possibility of postoperative tumor recurrence and postoperative complications can be reduced, so as to improve the survival rate of patients. At present, it is of great clinical value and widely carried out. This article will review the development of anatomical hepatectomy of hepatic vein approach and the main points of laparoscopic anatomical hepatectomy of hepatic vein approach.

9.
Nat Commun ; 10(1): 2037, 2019 05 02.
Article in English | MEDLINE | ID: mdl-31048690

ABSTRACT

Genome-wide analysis of genomic signatures might reveal novel mechanisms for gastric cancer (GC) tumorigenesis. Here, we analysis structural variations (SVs) and mutational signatures via whole-genome sequencing of 168 GCs. Our data demonstrates diverse models of complex SVs operative in GC, which lead to high-level amplification of oncogenes. We find varying proportion of tandem-duplications (TDs) among individuals and identify 24 TD hotspots involving well-established cancer genes such as CCND1, ERBB2 and MYC. Specifically, we nominate a novel hotspot involving the super-enhancer of ZFP36L2 presents in approximately 10% GCs from different cohorts, the oncogenic role of which is further confirmed by experimental data. In addition, our data reveal a mutational signature, specifically occurring in noncoding region, significantly enriched in tumors with cadherin 1 mutations, and associated with poor prognoses. Collectively, our data suggest that TDs might serve as an important mechanism for cancer gene activation and provide a novel signature for stratification.


Subject(s)
Oncogenes/genetics , Stomach Neoplasms/genetics , Transcription Factors/genetics , Transcriptome/genetics , Adult , Aged , Aged, 80 and over , Antigens, CD/genetics , Cadherins/genetics , Carcinogenesis/genetics , Cell Line, Tumor , Enhancer Elements, Genetic/genetics , Exons/genetics , Female , Gene Duplication/genetics , Genomic Structural Variation , Humans , Male , Middle Aged , Prognosis , Stomach/pathology , Stomach Neoplasms/mortality , Stomach Neoplasms/pathology , Survival Analysis , Whole Genome Sequencing
10.
Materials (Basel) ; 12(11)2019 May 28.
Article in English | MEDLINE | ID: mdl-31141962

ABSTRACT

Metallic nanowires (NWs) have attracted great attention in the frontiers of nanomaterial science due to their extraordinary properties, such as high thermal and electrical conductivity, high aspect ratio, good mechanical flexibility, and excellent optical transparency. The metallic NWs and their nanocomposites, as a promising alternative for conventional building materials, have been extensively studied recently, but review works on these novel versatile nanostructures and their various uses in the building and construction industry are still lacking. We present a comprehensive review on current state-of-the-art research and progress regarding multifunctional metallic NWs and their specific building applications, including thermal energy storage (TES), thermal transport, electrochromic windows (ECW), as well as photovoltaic (PV) cells. The nanosynthesis techniques and nanocharacterization of silver nanowires (AgNWs) and copper nanowires (CuNWs) are overviewed and compared with each other. In addition, the fundamentals of different NWs for advanced building applications are introduced. Further discussion is presented on the improved performance of base materials by using these nanostructures, highlighting the key factors exhibiting their superior performance. Finally, the key benefits and limitations of metallic NWs for new generation building materials are obtained.

13.
Plant Physiol Biochem ; 132: 633-640, 2018 Nov.
Article in English | MEDLINE | ID: mdl-30340175

ABSTRACT

In China, the high-oleic acid rapeseed has an oil content of ∼42% and oleic acid (18:1) content of ∼80%. Compared to ordinary rapeseed, high-oleic acid rapeseed has higher levels of monounsaturated fatty acids and lower levels of saturated fatty acid and polyunsaturated fatty acids, and thus is of high nutritional and health value. In addition, high-oleic acid rapeseed oil imparts cardiovascular protective effects. Based on these properties, high-oleic acid oil crops have been extensively investigated and cultivated. We previously identified a CCCH-type transcription factor (BnZFP1, GenBank accession number XM_013796508) that is associated with high oleic acid traits from a Brassica napus subtractive hybridization library. In the present study, we overexpressed and silenced the BnZFP1 gene of B. napus. BnZFP1-overexpressing plants exhibited an 18.8% increase in oleic acid levels and a 3.8% increase in oil content. However, BNZFP1-silenced plants showed a 4.5% decrease in oleic acid levels, whereas no significant change in oil content was observed. Microarray and pull-down assays indicated that BnZFP1 has a total of thirty potential target genes. Further analysis and validation of one of the potential target genes, namely, diacylglycerol O-acyltransferases 1 (DGAT1) gene, indicated that it is positively regulated by BnZFP1. We also observed a correlation between elevated DGAT1 gene expression levels and higher oil content and oleic acid levels in rapeseed.


Subject(s)
Brassica napus/enzymology , Brassica napus/genetics , Diacylglycerol O-Acyltransferase/genetics , Genes, Plant , Oleic Acid/metabolism , Plant Proteins/genetics , Biosynthetic Pathways/genetics , Diacylglycerol O-Acyltransferase/metabolism , Gene Expression Regulation, Plant , Lipid Metabolism/genetics , Oligonucleotide Array Sequence Analysis , Plant Proteins/metabolism , Plants, Genetically Modified , Promoter Regions, Genetic/genetics
14.
Front Genet ; 9: 240, 2018.
Article in English | MEDLINE | ID: mdl-30026755

ABSTRACT

Clustered Regularly Interspaced Palindromic Repeats (CRISPR) and Cascade 9 (also known as Cas9, CRISPR associated protein 9) confer protection against invading viruses or plasmids. The CRISPR/Cascade 9 system constitutes one of the most powerful genome technologies available to researchers today. So far, this technology has enabled efficient genome editing and modification in several model organisms and has successfully been used in biomedicine and biomedical engineering. However, challenges for efficient and safe genetic manipulation in several organisms persist. Here, we review functional approaches and future challenges associated with the use of the CRISPR/Cascade 9 genome editing system and discuss opportunities, ethical issues and future directions within this field.

15.
Oncotarget ; 9(44): 27412-27422, 2018 Jun 08.
Article in English | MEDLINE | ID: mdl-29937994

ABSTRACT

Colorectal cancer is the fifth prevalent cancer in China. Nevertheless, a large-scale characterization of Chinese colorectal cancer mutation spectrum has not been carried out. In this study, we have performed whole exome-sequencing analysis of 98 patients' tumor samples with matched pairs of normal colon tissues using Illumina and Complete Genomics high-throughput sequencing platforms. Canonical CRC somatic gene mutations with high prevalence (>10%) have been verified, including TP53, APC, KRAS, SMAD4, FBXW7 and PIK3CA. PEG3 is identified as a novel frequently mutated gene (10.6%). APC and Wnt signaling exhibit significantly lower mutation frequencies than those in TCGA data. Analysis with clinical characteristics indicates that APC gene and Wnt signaling display lower mutation rate in lymph node positive cancer than negative ones, which are not observed in TCGA data. APC gene and Wnt signaling are considered as the key molecule and pathway for colorectal cancer initiation, and these findings greatly undermine their importance in tumor progression for Chinese patients. Taken together, the application of next-generation sequencing has led to the determination of novel somatic mutations and alternative disease mechanisms in colorectal cancer progression, which may be useful for understanding disease mechanism and personalizing treatment for Chinese patients.

16.
Oncotarget ; 8(34): 56684-56697, 2017 Aug 22.
Article in English | MEDLINE | ID: mdl-28915622

ABSTRACT

Neuroblastoma (NB) is a childhood solid malignant tumor originating from precursor cells of the peripheral nervous system. We have previously established a risk classification system based on DNA copy number profiles. To further explore the pathogenesis of NBs in distinct risk groups, we performed whole-exome sequencing analysis of 57 primary and 7 recurrent/metastatic tumors with unique chromosomal aberration profiles as categorized by our genomic sub-grouping system. Overall, a low frequency of somatic mutations was found. Besides ALK (4/64, 6.3%), SEMA6C, SLIT1 and NRAS, genes involved in the axon guidance pathway, were identified as recurrently mutated in 6 of 64 tumors (9.4%). Pathway enrichment analysis revealed enrichment of 25 mutated genes in the mitogen-activated protein kinase (MAPK) pathway, 13 genes in the Wnt pathway, and 12 genes in the axon guidance pathway. Genomic analyses demonstrated that primary and matched recurrent or metastatic tumors obtained from sporadic and monozygotic twin NBs were clonally related with variable extents of genetic heterogeneity. Monozygotic twin NBs displayed different evolutionary trajectories. These results indicate the involvement of the axon guidance, MAPK and Wnt pathways in NB and demonstrate genomic diversity with NB progression.

17.
Oncotarget ; 8(30): 49851-49860, 2017 Jul 25.
Article in English | MEDLINE | ID: mdl-28591712

ABSTRACT

ESCC (Esophageal squamous cell carcinoma) is a heterogeneous cancer with diverse prognosis. Here, to explore the biological diversity of ESCC, we employed gene expression profiles from 360 ESCC tumors from East Asians to establish a comprehensive molecular classification and characterization of ESCC. Using the specific 185-gene signature generated by unsupervised consensus clustering of gene expression data, we defined four subtypes associated with distinct clinical metrics: tumors with high metastasis associated with EMT (epithelial to mesenchymal transition) and active MAP4K4/JNK signaling pathway; tumors with high chromosomal instability with up regulated MYC targes; well differentiated tumors with less aggressive and moderated tumors. The clinical relevance of these subtypes was stated by significant differences in prognosis. Importantly, 24% of all ESCCs (n = 360) were classified into the high metastasis subtype associated with poorly differentiation and unfavorable prognosis. We provided evidence that this subtype relates to tumor microenvironment. Collectively, these results might contribute to more precise personalized therapeutic strategies for each subtype of ESCC patients in the near future.


Subject(s)
Biomarkers, Tumor , Carcinoma, Squamous Cell/diagnosis , Esophageal Neoplasms/diagnosis , Carcinoma, Squamous Cell/drug therapy , Carcinoma, Squamous Cell/genetics , Carcinoma, Squamous Cell/mortality , Computational Biology/methods , Esophageal Neoplasms/drug therapy , Esophageal Neoplasms/genetics , Esophageal Neoplasms/mortality , Esophageal Squamous Cell Carcinoma , Female , Gene Expression Profiling , Gene Expression Regulation, Neoplastic/drug effects , Genetic Variation , Humans , Kaplan-Meier Estimate , Male , Molecular Targeted Therapy , Neoplasm Staging , Prognosis , Reproducibility of Results , Signal Transduction , Tumor Microenvironment/genetics
18.
J Hum Genet ; 62(8): 783-788, 2017 Aug.
Article in English | MEDLINE | ID: mdl-28381877

ABSTRACT

Intra-tumor heterogeneity is a big barrier to precision medicine. To explore the underlying clonal diversity in lung adenocarcinomas, we selected nine individuals with whole-genome sequencing data from primary and matched metastatic tumors as a cohort for study. Similar global pattern of arm-level copy number changes and large variations of somatic single-nucleotide variant between the primary and metastasis are observed in the majority of cases. Importantly, we found breakage-fusion-bridge (BFB) cycles acting as an important mechanism for underlying cancer gene amplification, such as amplification of CDK4, CDKN3 and FGFR1 in early stage. We also identified recurrent focal amplification of gene CCNY derived from BFB in two metastatic tumors, but not in primary tumor. Clonal analysis of case 236T demonstrated that mutational processes are varying with tumor progression. Collectively, our data provide new insights into genetic diversity and potential therapeutic target in lung adenocarcinoma.


Subject(s)
Adenocarcinoma/genetics , Biomarkers, Tumor/genetics , Gene Amplification , Genomics/methods , Lung Neoplasms/genetics , Mutation , Adenocarcinoma/secondary , DNA Copy Number Variations , Disease Progression , Genome, Human , Humans , Lung Neoplasms/pathology
19.
Am J Hum Genet ; 98(2): 256-74, 2016 Feb 04.
Article in English | MEDLINE | ID: mdl-26833333

ABSTRACT

Comprehensive identification of somatic structural variations (SVs) and understanding their mutational mechanisms in cancer might contribute to understanding biological differences and help to identify new therapeutic targets. Unfortunately, characterization of complex SVs across the whole genome and the mutational mechanisms underlying esophageal squamous cell carcinoma (ESCC) is largely unclear. To define a comprehensive catalog of somatic SVs, affected target genes, and their underlying mechanisms in ESCC, we re-analyzed whole-genome sequencing (WGS) data from 31 ESCCs using Meerkat algorithm to predict somatic SVs and Patchwork to determine copy-number changes. We found deletions and translocations with NHEJ and alt-EJ signature as the dominant SV types, and 16% of deletions were complex deletions. SVs frequently led to disruption of cancer-associated genes (e.g., CDKN2A and NOTCH1) with different mutational mechanisms. Moreover, chromothripsis, kataegis, and breakage-fusion-bridge (BFB) were identified as contributing to locally mis-arranged chromosomes that occurred in 55% of ESCCs. These genomic catastrophes led to amplification of oncogene through chromothripsis-derived double-minute chromosome formation (e.g., FGFR1 and LETM2) or BFB-affected chromosomes (e.g., CCND1, EGFR, ERBB2, MMPs, and MYC), with approximately 30% of ESCCs harboring BFB-derived CCND1 amplification. Furthermore, analyses of copy-number alterations reveal high frequency of whole-genome duplication (WGD) and recurrent focal amplification of CDCA7 that might act as a potential oncogene in ESCC. Our findings reveal molecular defects such as chromothripsis and BFB in malignant transformation of ESCCs and demonstrate diverse models of SVs-derived target genes in ESCCs. These genome-wide SV profiles and their underlying mechanisms provide preventive, diagnostic, and therapeutic implications for ESCCs.


Subject(s)
Carcinoma, Squamous Cell/genetics , Esophageal Neoplasms/genetics , Genetic Association Studies/methods , Genetic Variation , Cell Line , Cyclin D1/genetics , DNA Copy Number Variations , ErbB Receptors/genetics , Esophageal Squamous Cell Carcinoma , Gene Deletion , Gene Rearrangement , Genes, p16 , Genome, Human , Genomics , Humans , In Situ Hybridization, Fluorescence , Receptor, ErbB-2/genetics , Receptor, Fibroblast Growth Factor, Type 1/genetics , Receptor, Notch1/genetics , Reproducibility of Results , Sequence Analysis, RNA , Translocation, Genetic
20.
J Am Chem Soc ; 133(32): 12858-65, 2011 Aug 17.
Article in English | MEDLINE | ID: mdl-21736338

ABSTRACT

Polynitroaromatics are well-known to form anionic σ-complexes (Meisenheimer complexes). The formation of such complexes was assumed in the past to explain the blue color of solutions of 2,4-dinitrotoluene (DNT) and amines. However, this work shows that caution is warranted to avoid the hasty misidentification of Meisenheimer complexes. (1)H NMR spectra exhibit no significant shifts in the positions of the DNT protons, indicating that the majority of DNT species in solutions of DNT and amines retain their aromaticity. Density functional calculations on DNT-ethylamine complexes suggest that Meisenheimer complexes are sufficiently high in free energy so that they make up only a very small fraction of the full equilibrium population. While principal component analysis of the UV/vis spectra of the DNT-amine solutions reveals that only one absorbing species of significant concentration is formed, quantitative fits of Job's plots show that 1:1 association of DNT with the amines alone cannot explain the visible absorption spectra. Instead, the Job's plots can be accurately interpreted by deprotonation of DNT, with the amines acting as bases. The deprotonation equilibria lie far on the side of the unreacted DNT, preventing the detection by NMR of the deprotonated minority species that gives the solutions their strong blue color. The analysis of systems with DNT and n-butylamine, diethylamine, triethylamine, or benzylamine provides a consistent pK(a) of DNT in dimethyl sulfoxide of 15.3 ± 0.2.


Subject(s)
Amines/chemistry , Dinitrobenzenes/chemistry , Magnetic Resonance Spectroscopy , Models, Molecular , Protons , Quantum Theory
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