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1.
J Proteome Res ; 23(10): 4579-4588, 2024 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-39307995

RESUMO

This study aimed to investigate the dysregulated proteins and the underlying mechanisms of gastric precancerous lesions. Proteomic and phosphoproteomic methods were used to characterize the proteome and phosphoproteome profiles of N-methyl-N-nitro-N-nitrosoguanidine (MNNG)-induced gastric precancerous lesions. The hub differentially expressed proteins (DEPs) and phosphoproteins (DEPPs) were identified by using differential expression and protein-protein interaction network analyses. Western blot assay, quantitative reverse transcription (qRT)-PCR, and CCK-8 assays detected the expression of Rps3, N-cadherin, E-cadherin, AKT, p-AKT, and ß-catenin and verified the roles of Rps3 on the MNNG-induced human gastric epithelial cell line (GES-1) cells. Hub DEPs and phosphoproteins Rps3, Akt1, and Ctnnb1 were significantly correlated with five dendritic cells (DCs) pathways, and Akt1 and Ctnnb1 were significantly negatively correlated with Rps3. MNNG administration markedly reduced the Rps3 mRNA and protein expression levels (all P < 0.05). Overexpression of Rps3 significantly inhibited tumorigenesis of MNNG-induced GES-1 cells (all P < 0.01) and changed the protein levels of N-cadherin, E-cadherin, AKT, p-AKT, and ß-catenin. Similarly, SC79 treatment substantially increased the expression of interleukin (IL)-6, IL-10, and vascular endothelial growth factor (all P < 0.05). Rps3 was poorly expressed in precancerous gastric lesions. Correspondingly, overexpression of Rps3 promoted DC maturation via the AKT/ß-catenin pathway, inhibiting the progression of gastric precancerous lesions.


Assuntos
Células Dendríticas , Lesões Pré-Cancerosas , Proteínas Proto-Oncogênicas c-akt , Proteínas Ribossômicas , Neoplasias Gástricas , beta Catenina , beta Catenina/metabolismo , beta Catenina/genética , Humanos , Proteínas Proto-Oncogênicas c-akt/metabolismo , Proteínas Proto-Oncogênicas c-akt/genética , Neoplasias Gástricas/metabolismo , Neoplasias Gástricas/patologia , Neoplasias Gástricas/genética , Lesões Pré-Cancerosas/patologia , Lesões Pré-Cancerosas/metabolismo , Lesões Pré-Cancerosas/induzido quimicamente , Lesões Pré-Cancerosas/genética , Células Dendríticas/metabolismo , Proteínas Ribossômicas/genética , Proteínas Ribossômicas/metabolismo , Metilnitronitrosoguanidina/farmacologia , Transdução de Sinais , Animais , Proteômica/métodos , Mapas de Interação de Proteínas , Linhagem Celular , Camundongos
2.
J Am Chem Soc ; 146(13): 8832-8838, 2024 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-38507251

RESUMO

How mutations impact protein stability and structure dynamics is crucial for understanding the pathological process and rational drug design. Herein, we establish a time-resolved native mass spectrometry (TR-nMS) platform via a rapid-mixing capillary apparatus for monitoring the acid-initiated protein unfolding process. The molecular details in protein structure unfolding are further profiled by a 193 nm ultraviolet photodissociation (UVPD) analysis of the structure-informative photofragments. Compared with the wild-type dihydrofolate reductase (WT-DHFR), the M42T/H114R mutant (MT-DHFR) exhibits a significant stability decrease in TR-nMS characterization. UVPD comparisons of the unfolding intermediates and original DHFR forms indicate the special stabilization effect of cofactor NADPH on DHFR structure, and the M42T/H114R mutations lead to a significant decrease in NADPH-DHFR interactions, thus promoting the structure unfolding. Our study paves the way for probing the mutation-induced subtle changes in the stability and structure dynamics of drug targets.


Assuntos
Escherichia coli , Desdobramento de Proteína , Escherichia coli/metabolismo , NADP/metabolismo , Estabilidade Proteica , Mutação , Espectrometria de Massas , Tetra-Hidrofolato Desidrogenase/metabolismo
3.
J Synchrotron Radiat ; 31(Pt 5): 1010-1018, 2024 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-39042579

RESUMO

The damage threshold of an Au-coated flat mirror, one of the reflective optics installed on the FEL-2 beamline of the Dalian Coherent Light Source, China, upon far-UV free-electron laser irradiation is evaluated. The surface of the coating is characterized by profilometer and optical microscope. A theoretical approach of the phenomenon is also presented, by application of conventional single-pulse damage threshold calculations, a one-dimensional thermal diffusion model, as well as finite-element analysis with ANSYS.

4.
Clin Genet ; 2024 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-39380244

RESUMO

Empty follicle syndrome (EFS) is a disorder characterised by the unsuccessful retrieval of oocytes from matured follicles following ovarian stimulation for in vitro fertilisation (IVF). Genetic factors significantly contribute to this pathology. To date, an increasing number of genetic mutations associated with GEFS have been documented, however, some cases still remain unexplained by these previously reported mutations. Here, we identified a novel homozygous missense ZP1 variant (c.1096 C > T, p.Arg366Trp) in a female patient with GEFS from a consanguineous family who failed to retrieve any oocytes during two cycles of IVF treatment. We conducted a molecular dynamics simulation analysis on the mutant ZP1 model, revealing that the mutant ZP1 protein has an altered 3D structure, lower fluctuation, higher compactness and higher instability than wild-type ZP1. Immunostaining, immunoblotting and co-immunoprecipitation results showed that the homozygous missense mutation in ZP1 impaired protein secretion and weakened interactions between ZP1 and other ZP proteins, which may affect the ZP assembly. This study contributes to a more comprehensive understanding of the genetic aetiopathogenesis of GEFS.

5.
Opt Express ; 32(4): 5031-5042, 2024 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-38439240

RESUMO

Modern X-ray free-electron lasers (XFELs) can generate pulses with durations ranging from femtoseconds to attoseconds. The numerical evaluation of ultra-short XFEL pulses through beamline systems is a critical process of beamline system design. However, the bandwidth of such ultra-short XFEL pulses is often non-negligible, and the propagation cannot be simply approximated using the central wavelength, especially in dispersive beamline systems. We developed a numerical model which is called Fourier optics based Ultrashort x-Ray pulse propagatION tool (FURION). This model can not only be used to simulate dispersive beamline systems but also to evaluate non-dispersive beamline systems. The FURION model utilizes Fresnel integral and angular spectrum integral to perform ultra-short XFEL pulse propagation in free space. We also present the method for XFEL pulse propagation through different types of dispersive gratings, which are commonly used in soft X-ray beamline systems. By using FURION, a start-to-end simulation of the FEL-1 beamline system at Shenzhen superconducting soft X-ray free electron laser (S3FEL) is carried out. This model can also be used to evaluate gratings-based spectrometers, beam splitters, pulse compressors, and pulse stretchers. This work provides valuable insights into the start-to-end simulation of X-ray beamline systems.

6.
J Chem Phys ; 160(16)2024 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-38661196

RESUMO

Produced by both nature and human activities, sulfur dioxide (SO2) is an important species in the earth's atmosphere. SO2 has also been found in the atmospheres of other planets and satellites in the solar system. The photoabsorption cross sections and photodissociation of SO2 have been studied for several decades. In this paper, we reported the experimental results for photodissociation dynamics of SO2 via the G̃1B1 state. By analyzing the images from the time-sliced velocity map ion imaging method, the vibrational state population distributions and anisotropy parameters were obtained for the O(1D2) + SO(X3Σ-, a1Δ, b1Σ+) and O(1S0) + SO(X3Σ-) channels, and the branching ratios for the channels O(1D2) + SO(X3Σ-), O(1D2) + SO(a1Δ), and O(1D2) + SO(b1Σ+) were determined to be ∼0.3, ∼0.6, and ∼0.1, respectively. The SO products were dominant in electronically and rovibrationally excited states, which may have yet unrecognized roles in the upper planetary atmosphere.

7.
J Infect Chemother ; 30(6): 544-547, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37992864

RESUMO

Streptococcus suis is a pathogen of emerging zoonotic diseases and meningoencephalitis is the most frequent clinical symptom of S. suis infection in humans. Rapid diagnosis of S. suis meningoencephalitis is critical for the treatment of the disease. While the current routine microbiological tests including bacterial culture and gram staining are poorly sensitive, diagnosis of S. suis meningoencephalitis by metagenomic next-generation sequencing (mNGS) has been rarely reported. Here, we report a 52-year-old female pork food producer with a broken finger developed S. suis meningoencephalitis. After her admission, no pathogenic bacteria were detected through bacterial culture and Gram staining microscopy in the cerebrospinal fluid obtained via lumbar puncture. However, mNGS identified the presence of S. suis in the sample. mNGS is a promising diagnostic tool for rapid diagnosis of rare infectious diseases in the central nervous system.

8.
Proc Natl Acad Sci U S A ; 118(20)2021 05 18.
Artigo em Inglês | MEDLINE | ID: mdl-33975960

RESUMO

Biosyntheses of chlorophyll and heme in oxygenic phototrophs share a common trunk pathway that diverges with insertion of magnesium or iron into the last common intermediate, protoporphyrin IX. Since both tetrapyrroles are pro-oxidants, it is essential that their metabolism is tightly regulated. Here, we establish that heme-derived linear tetrapyrroles (bilins) function to stimulate the enzymatic activity of magnesium chelatase (MgCh) via their interaction with GENOMES UNCOUPLED 4 (GUN4) in the model green alga Chlamydomonas reinhardtii A key tetrapyrrole-binding component of MgCh found in all oxygenic photosynthetic species, CrGUN4, also stabilizes the bilin-dependent accumulation of protoporphyrin IX-binding CrCHLH1 subunit of MgCh in light-grown C. reinhardtii cells by preventing its photooxidative inactivation. Exogenous application of biliverdin IXα reverses the loss of CrCHLH1 in the bilin-deficient heme oxygenase (hmox1) mutant, but not in the gun4 mutant. We propose that these dual regulatory roles of GUN4:bilin complexes are responsible for the retention of bilin biosynthesis in all photosynthetic eukaryotes, which sustains chlorophyll biosynthesis in an illuminated oxic environment.


Assuntos
Pigmentos Biliares/fisiologia , Chlamydomonas reinhardtii/metabolismo , Clorofila/biossíntese , Peptídeos e Proteínas de Sinalização Intracelular/fisiologia , Cianobactérias/metabolismo , Heme Oxigenase (Desciclizante) , Peptídeos e Proteínas de Sinalização Intracelular/química , Liases/metabolismo , Protoporfirinas/química
9.
Artigo em Inglês | MEDLINE | ID: mdl-38466061

RESUMO

Background: In recent years, Tiaoshen acupuncture in Traditional Chinese Medicine (TCM) has been employed for treating patients with insomnia, but the clinical efficacy remains to be substantiated. Objective: To assess the efficacy and safety of acupuncture in treating insomnia using the Tiaoshen method in TCM. Design: A systematic review and meta-analysis was conducted. Setting: The research was conducted in Shenzhen. Methods: Electronic databases, including Chinese National Knowledge Infrastructure (CNKI), Wanfang, SinoMed, Weipu, PubMed, Web of Science, EMBASE, and Cochrane databases, were retrieved up to September 15, 2023. Randomized controlled trials (RCTs) meeting inclusion criteria were screened. Quality assessment of included articles was performed using the Cochrane Risk of Bias tool. Valid data were then extracted and analyzed via meta-analysis using Review Manager 5.3. The study was registered in the International Platform of Registered Systematic Review and Meta-analysis Protocols (INPLASY), 2023100051. Results: A total of 13 articles were included, comprising 849 patients with insomnia (diagnosed as chronic insomnia or primary insomnia). Meta-analysis results indicated that acupuncture with the Tiaoshen method could decrease the Pittsburgh Sleep Quality Index (PSQI) score [RR=-3.03, 95% CI (-3.73, -2.33), P < .00001], hyperarousal (HAS) scale score [RR=-7.75, 95% CI (-12.29, -3.22), P < .0008], and fatigue scale-14 (FS-14) score [RR=-2.11, 95% CI (-2.83, -1.38), P < .00001] compared with superficial acupuncture on non-effective acupoints or conventional acupuncture manipulation. Additionally, acupuncture with the Tiaoshen method demonstrated safety. However, the funnel plot suggested the presence of publication bias. Conclusions: Acupuncture with the Tiaoshen method could enhance sleep quality and efficiency. Due to the low quality of some literature, further high-quality RCTs are needed to improve the level of evidence.

10.
Ecotoxicol Environ Saf ; 270: 115842, 2024 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-38104434

RESUMO

To reduce the application dosage of thiamethoxam (TMX), we investigated the deposition and dissipation patterns in a pepper-planted ecosystem under different planting modes across four regions in China, namely Hainan (HN), Zhejiang (ZJ), Anhui (AH) and Hebei (HB). This study focused on the deposition and dissipation of TMX at concentrations of 63.00, 47.25, 31.50, 23.63 and 15.75 g a.i.hm-2. As the application dose increased, the deposition amount of TMX initially increased in the plants and cultivated soil, showing obvious geographic differences in four cultivation areas. Surprisingly, the initial amount of TMX deposited the pepper-cultivated greenhouse of ZJ and AH was 1.1-2.1-fold and 1.0-3.6-fold higher than that in the open field system at the same application dose, respectively. In pepper leaves, stems, fruits and soil, the dissipation exhibited rapid growth and then slowed. However, the residual concentration showed an increasing trend, followed by a subsequent decrease in the pepper roots. In different planting regions, the dissipation rate of TMX followed the order HN > ZJ > AH > HB in pepper plants and cultivated soil. In comparison to the open field, the total TMX retention rate in greenhouse was higher, indicating overall greater persistence in the greenhouse conditions. These findings reveal the deposition and dissipation characteristics of TMX within the pepper-field ecosystem, offering a significant contribution to the risk assessment of pesticides.


Assuntos
Inseticidas , Praguicidas , Tiametoxam , Inseticidas/análise , Ecossistema , Solo
11.
Zhonghua Yi Xue Yi Chuan Xue Za Zhi ; 41(8): 897-902, 2024 Aug 10.
Artigo em Zh | MEDLINE | ID: mdl-39097269

RESUMO

OBJECTIVE: To explore the genetic characteristics of a fetus with sex chromosome abnormality indicated by non-invasive prenatal testing (NIPT) at 25+ gestational weeks. METHODS: A pregnant woman who was admitted to the Taizhou Hospital for abnormal NIPT result on January 6, 2023 was selected as the study subject. Relevant clinical data was collected. The fetus was subjected to chromosomal karyotyping analysis, copy number variation sequencing (CNV-seq), fluorescence in situ hybridization (FISH), and multiplex PCR assays. RESULTS: NIPT had suggested monosomy of X chromosome. The fetus was found to have a chromosomal karyotype of 45,X[59]/46,X,del(Y)(q11.2)[17] at 30+ weeks of gestational age. CNV-seq suggested the presence a 7.98 Mb deletion at Yq11.222q12 and a mosaicism 16.92 Mb deletion. FISH suggested that the fetus harbored two SRY genes and a mosaicism sex chromosomal abnormality, and multiplex PCR revealed that its AZF b+c region was completely deleted. C-banded karyotyping showed darkly stained dense mitotic granules at both ends of the Y chromosome. The fetus was ultimately determined as a 45,X/46,X,idic(Y)(q11.2) mosaicism. Following elected abortion, testing of the fetal tissue confirmed the presence of 45,X/46,XY mosaicism, and CNV-seq result of the placental tissue was compatible with that of NIPT. CNV-seq analysis of the couple revealed no obvious abnormality. CONCLUSION: With combined NIPT, karyotyping, CNV-seq, FISH and multiplex PCR assays, the fetus was diagnosed as a 45,X/46,X,idic(Y)(q11.2) mosaicism with deletion of the AZF b+c region. Above finding has enabled prenatal diagnosis for the fetus.


Assuntos
Cromossomos Humanos X , Hibridização in Situ Fluorescente , Cariotipagem , Mosaicismo , Aberrações dos Cromossomos Sexuais , Humanos , Mosaicismo/embriologia , Feminino , Gravidez , Cromossomos Humanos X/genética , Adulto , Aberrações dos Cromossomos Sexuais/embriologia , Diagnóstico Pré-Natal , Feto , Variações do Número de Cópias de DNA , Cromossomos Humanos Y/genética , Masculino , Testes Genéticos/métodos
12.
J Transl Med ; 21(1): 603, 2023 09 07.
Artigo em Inglês | MEDLINE | ID: mdl-37679727

RESUMO

BACKGROUND: The early differential diagnosis between bacterial meningitis (BM) and tuberculous meningitis (TBM) or cryptococcal meningitis (CM) remains a significant clinical challenge. Neutrophil Gelatinase-Associated Lipocalin (NGAL) has been reported as a novel inflammatory biomarker in the early stages of infection. This study aimed to investigate whether cerebrospinal fluid (CSF) NGAL can serve as a potential biomarker for distinguishing between BM and TBM or CM. METHODS: We prospectively enrolled the patients with suspected CNS infections at admission and divided them into three case groups: BM (n = 67), TBM (n = 55), CM (n = 51), and an age- and sex-matched hospitalized control (HC, n = 58). Detected the CSF NGAL and assessed its diagnostic accuracy in distinguishing between BM and TBM or CM. Additionally, longitudinally measured the CSF NGAL levels in patients with BM to evaluate its potential as a monitoring tool for antibacterial treatment. RESULTS: The concentration of CSF NGAL in BM was significantly higher than in TBM, CM, and HC (all P < 0.05), while the serum NGAL did not show significant differences among the three case groups. The ROC analysis demonstrated that CSF NGAL presented a good diagnostic performance with an AUC of 0.834 (0.770-0.886) and at the optimal cutoff value of 74.27 ng/mL with 70.15% sensitivity and 77.36% specificity for discriminating BM with TBM and CM. Additionally, the CSF NGAL in the convalescent period of BM was significantly lower than in the acute period (P < 0.05). CONCLUSIONS: CSF NGAL may serve as a potential biomarker for distinguishing between acute BM and TBM or CM. Additionally, it holds clinical significance in monitoring the effectiveness of antibiotic therapy for BM.


Assuntos
Meningites Bacterianas , Meningite Criptocócica , Tuberculose Meníngea , Humanos , Antibacterianos , Lipocalina-2 , Meningites Bacterianas/diagnóstico , Meningite Criptocócica/diagnóstico , Estudos Prospectivos , Tuberculose Meníngea/diagnóstico
13.
New Phytol ; 239(5): 1989-2006, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37329247

RESUMO

Legume nodules produce large quantities of heme required for the synthesis of leghemoglobin (Lb) and other hemoproteins. Despite the crucial function of Lb in nitrogen fixation and the toxicity of free heme, the mechanisms of heme homeostasis remain elusive. Biochemical, cellular, and genetic approaches were used to study the role of heme oxygenases (HOs) in heme degradation in the model legume Lotus japonicus. Heme and biliverdin were quantified and localized, HOs were characterized, and knockout LORE1 and CRISPR/Cas9 mutants for LjHO1 were generated and phenotyped. We show that LjHO1, but not the LjHO2 isoform, is responsible for heme catabolism in nodules and identify biliverdin as the in vivo product of the enzyme in senescing green nodules. Spatiotemporal expression analysis revealed that LjHO1 expression and biliverdin production are restricted to the plastids of uninfected interstitial cells. The nodules of ho1 mutants showed decreased nitrogen fixation, and the development of brown, rather than green, nodules during senescence. Increased superoxide production was observed in ho1 nodules, underscoring the importance of LjHO1 in antioxidant defense. We conclude that LjHO1 plays an essential role in degradation of Lb heme, uncovering a novel function of nodule plastids and uninfected interstitial cells in nitrogen fixation.


Assuntos
Lotus , Fixação de Nitrogênio , Fixação de Nitrogênio/genética , Lotus/metabolismo , Heme Oxigenase (Desciclizante)/genética , Heme Oxigenase (Desciclizante)/metabolismo , Biliverdina/metabolismo , Leghemoglobina/genética , Simbiose/genética , Nódulos Radiculares de Plantas/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Regulação da Expressão Gênica de Plantas
14.
Opt Express ; 31(20): 31969-31981, 2023 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-37859010

RESUMO

In soft X-ray free-electron laser (FEL) beamlines, variable-line-spacing (VLS) gratings are often used as dispersive components of monochromators and spectrometers due to their combined dispersion and focusing properties. X-ray FEL pulses passing through the VLS grating can result in not only transverse focusing but also spatiotemporal coupling effects, such as pulse front tilt, pulse front rotation, and pulse stretching. In this paper, we present a theoretical study of the spatiotemporal response of concave VLS gratings to ultra-short X-ray pulses. The theoretical analysis indicates that the tilt angle of the non-zero diffraction orders varies with the propagation distance, and disappears at the focus, where the focal lengths and pulse stretching differ for different diffraction orders. The model demonstrates the pulse duration after the concave VLS grating is the convolution of the initial pulse duration and the stretching term induced by dispersion, while the beam size at the focus in x dimension is the convolution of the geometric scaling beam size and the dispersion term. This work provides a mathematical explanation for the spatiotemporal response of concave VLS grating to ultra-short X-ray pulses and offers valuable insights into the design of FEL grating monochromators, spectrometers, pulse compressors, and pulse stretchers.

15.
Crit Care ; 27(1): 114, 2023 03 18.
Artigo em Inglês | MEDLINE | ID: mdl-36934293

RESUMO

BACKGROUND: Although subcutaneous edema is a common symptom of critically ill patients, it is still underreported due to the lack of a systematic method for evaluating it. The present study aims to describe the occurrence and distribution of subcutaneous edema, as well as the risk factors associated with it, in critically ill patients using the focused liquid ultrasonography in dropsy (FLUID) protocol, and to assess their impact on ICU mortality. METHODS: The FLUID protocol and the pitting test were performed on general ICU patients in China. Cohen's Kappa coefficient and Bland-Altman plots were used to evaluate the agreement between the two methods at each measurement site and between the whole-body subcutaneous edema scores, respectively, while a repeated measures ANOVA was performed to compare the differences between the two methods in whole-body and body-part measurements. A generalized linear model was used to evaluate the risk factors for subcutaneous edema development and the relationship between subcutaneous edema severity and ICU mortality. RESULTS: A total of 145 critically ill patients were evaluated using both approaches, of whom 40 (27.6%) experienced subcutaneous edema. Over 1440 measurements, it was found that ultrasound discovered more subcutaneous edema than the pitting test (ultrasound: 522[36.3%], pitting test: 444[30.8%], χ2 = 9.477, p = 0.002). The FLUID protocol scored edema severity significantly higher than the pitting test in the whole body and specific body parts, including the abdominal wall, thighs, chest wall, and hands. Subcutaneous edema exhibited gravity-dependent distribution patterns, particularly in the abdominal wall. The APACHE II, NT-proBNP, serum creatinine, and sepsis were independent risk factors for subcutaneous edema development. The score of ultrasonic subcutaneous edema was related to ICU mortality. CONCLUSIONS: The FLUID protocol provides a comprehensive strategy for the semi-quantitative assessment of subcutaneous edema in critically ill patients. In detecting the onset and severity of edema, ultrasound was found to outperform the pitting test. Subcutaneous edema showed a gravity-dependent distribution pattern, and its severity was associated with mortality.


Assuntos
Estado Terminal , Unidades de Terapia Intensiva , Humanos , Edema/diagnóstico por imagem , APACHE , Ultrassonografia
16.
J Chem Phys ; 159(2)2023 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-37428055

RESUMO

The vibrationally excited reaction O(1D) + CHD3(ν1 = 1) has been investigated by crossed-molecular-beam experiments with a time-sliced velocity map imaging technique. Detailed and quantitative information is extracted on the C-H stretching excitation effects on the reactivity and dynamics of the title reaction, with the help of preparation of C-H stretching excited CHD3 molecules by direct infrared excitation. Experimental results show that the vibrational stretching excitation of the C-H bond almost does not affect the relative contributions between different dynamical pathways for all product channels. For the OH + CD3 product channel, the vibrational energy of the C-H stretching excited CHD3 reagent is channeled exclusively into the vibrational energy of the OH products. The vibrational excitation of the CHD3 reactant changes the reactivities for the ground-state and umbrella-mode-excited CD3 channels very modestly, while it significantly suppresses the corresponding CHD2 channels. For the CHD2(ν1 = 1) channel, the stretching excited C-H bond of the CHD3 molecule acts almost as a pure spectator.

17.
J Chem Phys ; 158(1): 014301, 2023 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-36610966

RESUMO

Structural characterization of neutral water clusters is crucial to understanding the structures and properties of water, but it has been proven to be a challenging experimental target due to the difficulty in size selection. Here, we report the size-specific infrared spectra of confinement-free neutral water nonamer (H2O)9 based on threshold photoionization, using a tunable vacuum ultraviolet free-electron laser. Distinct OH stretch vibrational fundamentals in the 3200-3350 cm-1 region are observed, providing unique spectral signatures for the formation of an unprecedented (H2O)9 structure evolved by adding a ninth water molecule onto a hydrogen bond-unbroken edge of the (H2O)8 octamer with D2d symmetry. This nonamer structure coexists with the five previously identified structures that can be viewed as derived by inserting a ninth water molecule into a hydrogen bond-broken edge of the D2d/S4 octamer. These findings provide key microscopic information for systematic understanding of the formation and growth mechanism of dynamical hydrogen-bonding networks that are responsible for the structure and properties of condensed-phase water.

18.
Proc Natl Acad Sci U S A ; 117(27): 15423-15428, 2020 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-32541029

RESUMO

Infrared spectroscopic study of neutral water clusters is crucial to understanding of the hydrogen-bonding networks in liquid water and ice. Here we report infrared spectra of size-selected neutral water clusters, (H2O) n (n = 3-6), in the OH stretching vibration region, based on threshold photoionization using a tunable vacuum ultraviolet free-electron laser. Distinct OH stretch vibrational fundamentals observed in the 3,500-3,600-cm-1 region of (H2O)5 provide unique spectral signatures for the formation of a noncyclic pentamer, which coexists with the global-minimum cyclic structure previously identified in the gas phase. The main features of infrared spectra of the pentamer and hexamer, (H2O) n (n = 5 and 6), span the entire OH stretching band of liquid water, suggesting that they start to exhibit the richness and diversity of hydrogen-bonding networks in bulk water.

19.
J Asian Nat Prod Res ; 25(4): 330-341, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35788164

RESUMO

Two new furanoeremophilane sesquiterpenoids, namely, 6,9-dioxo-1α,4α-dihydroxy-furanoeremophilane (1) and 4α,5α-epoxy-6,9-dioxo-1α-hydroxyl-furanoeremophilane (2), and 10 known compounds were isolated from the whole plant of Chloranthus multistachys, and compound 3 was converted to derivative 3a. Their structures were determined based on extensive spectroscopic analysis. All compounds were evaluated by using five cancer cell lines: PC3, LNcap, A549, K562, and HEL. The derivative 3a exhibited excellent cytotoxic activities, with the IC50 against HEL cells being the lowest at 1.322 ± 0.08 µM, which was comparable to that of the positive control (doxorubicin). Mechanism studies showed that the anticancer activity of 3a may be associated with cell cycle regulation.


Assuntos
Antineoplásicos , Neoplasias , Sesquiterpenos de Eudesmano , Sesquiterpenos , Humanos , Sesquiterpenos/química , Linhagem Celular , Estrutura Molecular , Linhagem Celular Tumoral
20.
Molecules ; 28(4)2023 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-36838670

RESUMO

Citrus peels are rich in bioactive compounds such as vitamin C and extraction of vitamin C is a good strategy for citrus peel recycling. It is essential to evaluate the levels of vitamin C in citrus peels before reuse. In this study, a near-infrared (NIR)-based method was proposed to quantify the vitamin C content of citrus peels in a rapid way. The spectra of 249 citrus peels in the 912-1667 nm range were acquired, preprocessed, and then related to measured vitamin C values using the linear partial least squares (PLS) algorithm, indicating that normalization correction (NC) was more suitable for spectral preprocessing and NC-PLS model built with full NC spectra (375 wavelengths) showed a better performance in predicting vitamin C. To accelerate the predictive process, wavelength selection was conducted, and 15 optimal wavelengths were finally selected from NC spectra using the stepwise regression (SR) method, to predict vitamin C using the multiple linear regression (MLR) algorithm. The results showed that SR-NC-MLR model had the best predictive ability with correlation coefficients (rP) of 0.949 and root mean square error (RMSEP) of 14.814 mg/100 mg in prediction set, comparable to the NC-PLS model in predicting vitamin C. External validation was implemented using 40 independent citrus peels samples to validate the suitability of the SR-NC-MLR model, obtaining a good correlation (R2 = 0.9558) between predicted and measured vitamin C contents. In conclusion, it was reasonable and feasible to achieve the rapid estimation of vitamin C in citrus peels using NIR spectra coupled with MLR algorithm.


Assuntos
Ácido Ascórbico , Citrus , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Análise dos Mínimos Quadrados , Algoritmos , Vitaminas
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