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1.
PLoS One ; 15(1): e0227424, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31923251

RESUMO

BACKGROUND: Sofosbuvir (SOF)-based regimens achieve excellent efficacy and safety in the treatment of chronic hepatitis C (CHC) with various genotypes. There are few real-world instances of the use of SOF-based regimens to treat genotype 2 CHC. This study determines the effectiveness and safety of SOF/Ribavirn (RBV), SOF/Daclatasvir (DCV) and SOF/DCV/RBV in the treatment of genotype 2 CHC patients in Taiwan. MATERIAL AND METHODS: Patients with genotype 2 CHC were treated for 12 weeks with SOF/RBV, SOF/DCV or SOF/DCV/RBV under the National Health Insurance reimbursement program in three hospitals in Taiwan. The sustained virological response at 12 weeks (SVR12) was determined. Adverse events were recorded for a safety analysis. RESULTS: A total of 467 genotype 2 CHC patients were enrolled from January to October 2018. One hundred and eleven patients (24%) had cirrhosis, including 10 patients (2.1%) with hepatic decompensation. Fifty-five patients (12%) had already experienced interferon-alpha/RBV treatment. Forty-two patients (9%) had a history of hepatocellular carcinoma (HCC) in the baseline. Three hundred and fifty-five patients received SOF/RBV, forty-seven patients received SOF/DCV and sixty-two patients received SOF/DCV/RBV. The SOF/DCV group featured a greater HCV viral load than the SOF/RBV or SOF/DCV/RBV groups. SVR12 was achieved in 94.6% of the SOF/RBV group, 95.7% of the SOF/DCV group and 96.8% of then SOF/DCV/RBV group (P = NS). Thirteen out of 352 patients (3.7%) in the SOF/RBV group, 1 out of 62 patients (1.6%) in the SOF/DCV/RBV group and 1 out of 47 patients (2.1%) in the SOF/DCV group developed virological failure. There are no differences in virological failure between the three groups (P = NS). Multi-variate analysis shows that history of HCC is an independent factor that is associated with the failure of treatment in the SOF/RBV group (odds ratio:4.905, 95% confidence interval (CI): 1.321-18.205, P = 0.017). Hemoglobin levels at 12 weeks are significantly lower in the SOF/RBV and the SOF/RBV/DCV group than in the SOF/DCV group (P<0.05). Serious adverse events (SAE) occurred in six patients (1.6%) in the SOF/RBV group and in one patient (1.6%) in the SOF/RBV/DCV group. No patients in the SOF/DCV group experienced SAE. CONCLUSIONS: SOF/RBV, SOF/DCV or SOF/DCV/RBV for 12 weeks all achieve very high SVR rates and are equally effective in the treatment of genotype 2 CHC patients in the real world in Taiwan. Patients in the SOF/RBV group who have a history of HCC exhibit a lower SVR rate.

2.
Chem Commun (Camb) ; 2019 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-31807737

RESUMO

Herein, we disclosed an efficient protocol for the construction of chiral 3-allyl-3-hydroxyoxindoles via the enantioselective allylation reaction of isatins and allylboronates catalyzed by a simple binary acid Bi(OAc)3/CPA system under mild conditions. The synthetic utility of this strategy has been demonstrated through the formal synthesis of ent-CPC-1.

3.
World J Clin Cases ; 7(23): 4150-4156, 2019 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-31832421

RESUMO

BACKGROUND: Odontogenic infection is one of the common infectious diseases in oral and maxillofacial head and neck regions. Clinically, if early odontogenic infections such as acute periapical periodontitis, alveolar abscess, and pericoronitis of wisdom teeth are not treated timely, effectively and correctly, the infected tissue may spread up to the skull and brain, down to the thoracic cavity, abdominal cavity and other areas through the natural potential fascial space in the oral and maxillofacial head and neck. Severe multi-space infections are formed and can eventually lead to life-threatening complications (LTCs), such as intracranial infection, pleural effusion, empyema, sepsis and even death. CASE SUMMARY: We report a rare case of death in a 41-year-old man with severe odontogenic multi-space infections in the oral and maxillofacial head and neck regions. One week before admission, due to pain in the right lower posterior teeth, the patient placed a cigarette butt dipped in the pesticide "Miehailin" into the "dental cavity" to relieve the pain. Within a week, the infection gradually spread bilaterally to the floor of the mouth, submandibular space, neck, chest, waist, back, temporal and other areas. The patient had difficulty breathing, swallowing and eating, and was transferred to our hospital as an emergency admission. Following admission, oral and maxillofacial surgeons immediately organized consultations with doctors in otolaryngology, thoracic surgery, general surgery, hematology, anesthesia and the intensive care unit to assist with treatment. The patient was treated with the highest level of antibiotics (vancomycin) and extensive abscess incision and drainage in the oral, maxillofacial, head and neck, chest and back regions. Unfortunately, the patient died of septic shock and multiple organ failure on the third day after admission. CONCLUSION: Odontogenic infection can cause serious multi-space infections in the oral and maxillofacial head and neck regions, which can result in multiple LTCs. The management and treatment of LTCs such as multi-space infections should be multidisciplinary led by oral and maxillofacial surgeons.

4.
Acc Chem Res ; 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31823601

RESUMO

Because of their unique biological, physical, and chemical properties, organofluorine compounds play an increasingly important role in numerous areas of chemistry and everyday life. However, although fluorine is the most abundant halogen in the earth's crust and ranks 13th in abundance among all elements, naturally occurring organofluorine compounds are rare. Consequently, there is a growing demand for the development of safe and efficient reagents and selective synthetic methodologies for the introduction of fluorine or fluorine-containing groups into organic compounds. A wide variety of shelf-stable electrophilic fluorinating and fluoroalkylating reagents have been developed in the past decades. Some of them have also been shown to act as radical sources. These versatile reagents have promoted revolutionary advances in synthetic fluorine chemistry. These developments of novel reagents and the choice of suitable reagents for new reactions have relied largely on the traditional trial-and-error approach because (i) structure-reactivity relationships and mechanisms of reactions of these reagents are sparse and (ii) the rules that govern the synthesis of non-fluorinated analogues cannot necessarily be transposed to fluorinated compounds ( Cahard , D. ; et al. Chem. Soc. Rev. 2014 , 43 , 135 ), since organic fluorine compounds often exhibit unusual properties. Over the past several years, our studies have aimed at establishing comprehensive cation and radical donor scales of electrophilic F, CF3, and SCF3 transfer reagents. We have also developed detailed structure-reactivity relationships. We used density functional theory calculations to systematically investigate the energies required to heterolytically cleave the Y-F/CF3/SCF3 bonds to donate electrophilic F/CF3/SCF3 groups. We found that these energies can be used as convenient indicators of the relative electrophilic fluorinating/trifluoromethylating/trifluoromethylthiolating strengths of these reagents. We have constructed the first comprehensive cation donor scales for electrophilic F, CF3, and SCF3 transfer reagents. In collaboration with Mayr group, we experimentally determined the electrophilicity parameters of SCF3 transfer reagents and demonstrated the importance of intrinsic barriers for predicting their kinetic reactivity. The recognition of the novel application of a few traditional electrophilic reagents as radical sources prompted us further to construct comprehensive radical donor scales of electrophilic F, CF3, and SCF3 transfer reagents. We identified a series of potential new radical F, CF3, and SCF3 donors. Single electron transfer was found to exhibit a substantial effect on activation of the Y-CF3/SCF3 bonds, significantly facilitating the release of CF3/SCF3 radicals. This Account summarizes computational and experimental accomplishments from our group and others to establish the missing links between structure and reactivity for these reagents. Our results pave the way toward the rational optimization, design, and prediction of novel electrophilic fluorinating and fluoroalkylating reagents and new reactions.

5.
Artigo em Inglês | MEDLINE | ID: mdl-31691554

RESUMO

Water-repellent superhydrophobic (SH) surfaces promise a wide range of applications, from increased buoyancy to drag reduction, but their practical use is limited. This comes from the fact that an SH surface will start to lose its efficiency once it is forced into water or damaged by mechanical abrasion. Here, we circumvent these two most challenging obstacles and demonstrate a highly floatable multifaced SH metallic assembly inspired by the diving bell spiders and fire ant assemblies. We study and optimize, both theoretically and experimentally, the floating properties of the design. The assembly shows an unprecedented floating ability; it can float back to the surface even after being forced to submerge under water for months. More strikingly, the assembly maintains its floating ability even after severe damage and piercing in stark contrast to conventional watercrafts and aquatic devices. The potential use of the SH floating metallic assembly ranges from floating devices and electronic equipment protection to highly floatable ships and vessels.

6.
Opt Lett ; 44(23): 5691-5694, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31774755

RESUMO

Four surface-modified and, hence, positively charged metal nanoparticles (NPs) of different localized surface plasmon (LSP) resonance wavelengths are synthesized for linking with negatively charged, red-emitting colloidal CdZnSeS/ZnS quantum dots (QDs) on the top surface of a blue-emitting InGaN/GaN quantum well (QW) light-emitting diode (LED) through electro-static force. The metal NP-QD linkage leads to a short distance between them for producing their strong surface plasmon (SP) coupling, such that QD absorption and emission can be enhanced. Meanwhile, the small p-GaN thickness in the LED results in strong SP coupling between the LSP resonance of metal NP and the QWs of the LED, leading to enhanced QW emission and, hence, stronger QD excitation. All those factors together result in the increase of the color conversion efficiency of the QD.

7.
Nanotechnology ; 31(9): 095201, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31731282

RESUMO

With two different residual surfactants, four different metal nanoparticles (NPs), including two Au NPs and two Ag NPs are synthesized for linking with red-emitting CdZnSeS/ZnS colloidal quantum dots (QDs) to enhance QD emission efficiency. Those metal NPs are first connected with amino polyethylene glycol thiol of different molecular weights to avoid aggregation and make them positively charged. They can attract negatively charged QDs for inducing surface plasmon (SP) coupling such that either QD absorption or emission and hence overall color conversion efficiency can be enhanced. The enhancement of QD emission efficiency is evaluated through the comparison of time-resolved photoluminescence behaviors under different QD linkage conditions. Such results are confirmed by the measurement of the emission quantum efficiency of QD. It is found that by linking QDs onto Ag NPs, the QD emission efficiency is more enhanced, when compared with Au NPs. Also, depending on the synthesis process, the residual surfactant of citrate leads to a relatively large increment in QD emission efficiency, when compared to the surfactant of cetrimonium chloride. A more enhanced QD emission efficiency is caused by a higher QD linkage capability and a stronger SP coupling effect.

8.
Nanoscale ; 11(47): 22849-22859, 2019 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-31755508

RESUMO

Inorganic nanoparticles (NPs), particularly iron oxide (IO) and gold (Au) NPs, are widely used in a variety of biomedical applications, such as diagnosis and cancer therapy. As an important component of host defense in organisms, macrophages play a crucial role in responding to foreign substances, such as nanoparticles. Thus, it is of utmost importance to understand the nanotoxicity effects on the immune system by investigating the influences of such nanoparticles. In this study, we found that macrophages can take up large amounts of amphiphilic polymer (PMA)-modified Au and IO NPs, which will induce macrophage cell vacuolization and enhance macrophage polarization. This mechanism is an essential part of the immune response in vivo. In addition, we report that smaller-sized nanoparticles (ca. 4 nm) show more significant effects on the macrophage polarization and caused lysosomal damage compared to larger nanoparticles (ca. 14 nm). Moreover, the amount of NP uptake in macrophages decreases upon trapping the PMA with PEG, resulting in reduced vacuolization and a reduced immune response. We hypothesize that vacuoles are formed in large amounts during NP uptake by macrophages, which enhances the immune response and induces macrophages toward M1 polarization. These findings are potentially useful for disease treatment and understanding the immune response when NPs are used in vitro and in vivo.

9.
Cancers (Basel) ; 11(12)2019 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-31771238

RESUMO

Oral squamous cell carcinoma (OSCC) is one of the major leading causes of cancer death worldwide due to the limited availability of biomarkers and therapeutic targets. Autophagy related protease 4B (ATG4B) is an essential protease for the autophagy machinery, and ATG4B phosphorylation at Ser383/392 increases its proteolytic activity. ATG4B expression and activation are crucial for cancer cell proliferation and invasion. However, the clinical relevance of ATG4B and phospho-Ser383/392-ATG4B for OSCC remains unknown, particularly in buccal mucosal SCC (BMSCC) and tongue SCC (TSCC). With a tissue microarray comprising specimens from 498 OSCC patients, including 179 BMSCC and 249 TSCC patients, we found that the protein levels of ATG4B and phospho-Ser383/392-ATG4B were elevated in the tumor tissues of BMSCC and TSCC compared with those in adjacent normal tissues. High protein levels of ATG4B were significantly associated with worse disease-specific survival (DSS) in OSCC patients, particularly in patients with tumors at advanced stages. In contrast, phospho-Ser383/392-ATG4B expression was correlated with poor disease-free survival (DFS) in TSCC patients. Moreover, ATG4B protein expression was positively correlated with phospho-Ser383/392-ATG4B expression in both BMSCC and TSCC. However, high coexpression levels of ATG4B and phospho-Ser383/392-ATG4B were associated with poor DFS only in TSCC patients, whereas they had no significant association with DSS in BMSCC and TSCC patients. In addition, silencing ATG4B with an antisense oligonucleotide (ASO) or small interfering RNA (siRNA) diminished cell proliferation of TW2.6 and SAS oral cancer cells. Further, knockdown of ATG4B reduced cell migration and invasion of oral cancer cells. Taken together, these findings suggest that ATG4B might be a biomarker for diagnosis/prognosis of OSCC and a potential therapeutic target for OSCC patients.

10.
Molecules ; 24(22)2019 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-31703433

RESUMO

With the rapid consumption of energy, clean solar energy has become a key study and development subject, especially the when new renewable energy perovskite solar cells (PSCs) are involved. The doping method is a common means to modulate the properties of perovskite film. The main work of this paper is to incorporate trace amounts of alkali metal elements into the perovskite layer and observe the effects on the properties of the perovskite device and the majority carrier type of the perovskite film. Comparative analysis was performed by doping with Na+, K+, and Rb+ or using undoped devices in the perovskite layer. The results show that the incorporation of alkali metal ions into the perovskite layer has an important effect on the majority carrier type of the perovskite film. The majority carrier type of the undoped perovskite layer is N-type, and the majority carrier type of the perovskite layer doped with the alkali metal element is P-type. The carrier concentration of perovskite films is increased by at least two orders of magnitude after doping. That is to say, we can control the majority of the carrier type of the perovskite layer by controlling the doping subjectively. This will provide strong support for the development of future homojunction perovskite solar cells. This is of great help to improve the performance of PSC devices.

11.
J Exp Clin Cancer Res ; 38(1): 461, 2019 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-31706322

RESUMO

BACKGROUND: Tumor cell repopulation after radiotherapy is a major cause for the tumor radioresistance and recurrence. This study aims to investigate the underlying mechanism of tumor repopulation after radiotherapy, with focus on whether and how necroptosis takes part in this process. METHODS: Necroptosis after irradiation were examined in vitro and in vivo. And the growth-promoting effect of necroptotic cells was investigated by chemical inhibitors or shRNA against necroptosis associated proteins and genes in in vitro and in vivo tumor repopulation models. Downstream relevance factors of necroptosis were identified by western blot and chemiluminescent immunoassays. Finally, the immunohistochemistry staining of identified necroptosis association growth stimulation factor was conducted in human colorectal tumor specimens to verify the relationship with clinical outcome. RESULTS: Radiation-induced necroptosis depended on activation of RIP1/RIP3/MLKL pathway, and the evidence in vitro and in vivo demonstrated that the inhibition of necroptosis attenuated growth-stimulating effects of irradiated tumor cells on living tumor reporter cells. The JNK/IL-8 were identified as downstream molecules of pMLKL during necroptosis, and inhibition of JNK, IL-8 or IL-8 receptor significantly reduced tumor repopulation after radiotherapy. Moreover, the high expression of IL-8 was associated with poor clinical prognosis in colorectal cancer patients. CONCLUSIONS: Necroptosis associated tumor repopulation after radiotherapy depended on activation of RIP1/RIP3/MLKL/JNK/IL-8 pathway. This novel pathway provided new insight into understanding the mechanism of tumor radioresistance and repopulation, and MLKL/JNK/IL-8 could be developed as promising targets for blocking tumor repopulation to enhance the efficacy of colorectal cancer radiotherapy.

12.
Ann Surg Oncol ; 26(13): 4587-4598, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31605342

RESUMO

OBJECTIVES: To predict histopathologic growth patterns (HGPs) in colorectal liver metastases (CRLMs) with a noninvasive radiomics model. METHODS: Patients with chemotherapy-naive CRLMs who underwent abdominal contrast-enhanced multidetector CT (MDCT) followed by partial hepatectomy between January 2007 and January 2019 from two institutions were included in this retrospective study. Hematoxylin- and eosin-stained histopathologic sections of CRLMs were reviewed, with HGPs defined according to international consensus. Lesions were divided into training and validation datasets based on patients' sources. Radiomic features were extracted from pre- and post-contrast (arterial and portal venous) phase MDCT images, with review focusing on the segmented tumor-liver interface zones of CRLMs. Minimum redundancy maximum relevance and decision tree methods were used for radiomics modeling. Multivariable logistic regression analyses and ROC curves were used to assess the predictive performance of these models in predicting HGP types. RESULTS: A total of 126 CRLMs with histopathologic-demonstrated desmoplastic (n = 68) or replacement (n = 58) HGPs were assessed. The radiomics signature consisted of 20 features of each phase selected. The 3 phases fused radiomics signature demonstrated the best predictive performance in distinguishing between replacement and desmoplastic HGPs (AUCs of 0.926 and 0.939 in the training and external validation cohorts, respectively). The clinical-radiomics combined model showed good discrimination (C-indices of 0.941 and 0.833 in the training and external validation cohorts, respectively). CONCLUSIONS: A radiomics model derived from MDCT images may effectively predict the HGP of CRLMs, thus providing a basis for prognostic stratification and therapeutic decision-making.

13.
Cell Tissue Bank ; 20(4): 569-578, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31606766

RESUMO

Tissue engineering vascular grafts (TEVGs) have the potential to replace small-diameter grafts in bypass surgery which is good news for patients with cardiovascular disease. Decellularized arteries can be ideal TEVGs because their natural three-dimensional structures support the migration of host cells and vascular remodeling. There are many methods for decellularization without a standard protocol. In this study, a combination of Triton X-100 and sodium dodecyl sulfate (SDS) were used to prepare decellularized arteries. However, decellularization may damage the biochemical and mechanical properties to some degree. We used the cross-linking agents N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) to improve mechanical properties and immobilize heparin to inhibit thrombogenesis. Histological analysis, scanning electron microscopy, biomechanical properties test, determination of immobilized heparin, active partial thrombin time assay, and subcutaneous embedding experiment were used to evaluate the efficiency of decellularization and the efficacy of heparinized cross-linked vascular scaffold. Results showed 1% Triton X-100 combined with 0.3% SDS can decellularize successfully. EDC and NHS cross-linking can improve the mechanical properties, reduce the inflammatory reaction and slow the degradation time. Heparin immobilized on the scaffolds can inhibit thrombogenesis effectively. This study indicated the heparinized cross-linked vascular scaffolds may be ideal scaffolds for TEVGs.

14.
Sci Rep ; 9(1): 15285, 2019 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-31653891

RESUMO

Two complete chloroplast genome sequences of Asteropyrum, as well as those of 25 other species from Ranunculaceae, were assembled using both Illumina and Sanger sequencing methods to address the structural variation of the cp genome and the controversial systematic position of the genus. Synteny and plastome structure were compared across the family. The cp genomes of the only two subspecies of Asteropyrum were found to be differentiated with marked sequence variation and different inverted repeat-single copy (IR-SC) borders. The plastomes of both subspecies contains 112 genes. However, the IR region of subspecies peltatum carries 27 genes, whereas that of subspecies cavaleriei has only 25 genes. Gene inversions, transpositions, and IR expansion-contraction were very commonly detected in Ranunculaceae. The plastome of Asteropyrum has the longest IR regions in the family, but has no gene inversions or transpositions. Non-coding regions of the cp genome were not ideal markers for inferring the generic relationships of the family, but they may be applied to interpret species relationship within the genus. Plastid phylogenomic analysis using complete cp genome with Bayesian method and partitioned modeling obtained a fully resolved phylogenetic framework for Ranunculaceae. Asteropyrum was detected to be sister to Caltha, and diverged early from subfamily Ranunculoideae.

15.
Artigo em Inglês | MEDLINE | ID: mdl-31561624

RESUMO

Background: Child maltreatment has become a serious public health and social problem worldwide. However, knowledge regarding the status of child maltreatment in western China is limited. Objective: The objective of this study was to investigate the status of child maltreatment in western China and its relationship with mental health. Participants and setting: The present study evaluated child maltreatment in a sample of 1511 children (Mage = 11.48 years) from western China. Methods: The participants completed questionnaires designed to collect demographic information and assess their experiences with maltreatment and symptoms of depression and anxiety. Results: In total, 12.3%, 14.0%, 1.3% and 28.1% of the children experienced physical abuse, emotional abuse, sexual abuse and neglect, respectively, while 186 children (12.3%) experienced multiple types of maltreatment. Boys were more likely to experience maltreatment than girls in most cases. Physical abuse, emotional abuse, sexual abuse and neglect had unique effects on depression symptoms. Physical abuse, emotional abuse and neglect, but not sexual abuse, had unique effects on anxiety symptoms. Conclusions: The children who experienced maltreatment had higher levels of depressive and anxiety symptoms. Population-based prevention and educational programs should highlight the serious negative effects of maltreatment, especially emotional abuse and neglect, which have long been ignored in China.

16.
MAGMA ; 2019 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-31487004

RESUMO

OBJECTIVE: To provide a review and quantitative analysis of the available fetal MR imaging phantoms. MATERIALS AND METHODS: A literature search was conducted across Pubmed, Google Scholar, and Ryerson University Library databases to identify fetal MR imaging phantoms. Phantoms were graded on a semi-quantitative scale in regards to four evaluation categories: (1) anatomical accuracy in size and shape, (2) dielectric conductivity similar to the simulated tissue, (3) relaxation times similar to simulated tissue, and (4) physiological motion similar to fetal gross body, cardiovascular, and breathing motion. This was followed by statistical analysis to identify significant findings. RESULTS: Seventeen fetal phantoms were identified and had an average overall percentage accuracy of 26%, with anatomical accuracy being satisfied the most (56%) and physiological motion the least (7%). Phantoms constructed using 3D printing were significantly more accurate than conventionally constructed phantoms. DISCUSSION: Currently available fetal phantoms lack accuracy and motion simulation. 3D printing may lead to higher accuracy compared with traditional manufacturing. Future research needs to focus on properly simulating both fetal anatomy and physiological motion to produce a phantom that is appropriate for fetal MRI sequence development and optimization.

17.
J Am Chem Soc ; 141(40): 16046-16056, 2019 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-31514501

RESUMO

The work of Kita et al. on asymmetric oxidative dearomatization of naphthol carboxylic acids to spirolactones mediated/catalyzed by a novel, conformationally rigid µ-oxo-bridged hypervalent iodine(III) species is a landmark discovery in enantioselective iodine(III) catalysis [Kita, Y.; et al. Angew. Chem., Int. Ed. 2008, 47, 3787. DOI: 10.1002/anie.200800464 ; J. Am. Chem. Soc. 2013, 135, 4558. DOI: 10.1021/ja401074u ]. We have investigated the detailed mechanism of this important transformation using density functional theory. Calculations revealed that proton transfer from the pendant carboxylic acid of naphthols to the bridging oxygen atom or the ligand of iodine(III) species, which enhances the nucleophilicity of the carboxylic oxygen and the nucleofugality of the iodoarene, is crucial for the dearomatizing spirolactonization. Halogen bonding between the resulting carboxylate and the electron-deficient iodine(III) center further stabilizes the dearomatizing spirolactonization transition states. Calculations also revealed a long-neglected cleaved µ-oxo iodine(III) species that is more reactive but less selective than the µ-oxo-bridged hypervalent iodine(III) species itself for the oxidative dearomatization of naphthols. The coexistence of two sequential dearomatizing spirolactonization processes in the reaction system results in a lower enantioselectivity. A new stereochemical model that is able to reproduce and rationalize the observed apparent enantioselectivities is proposed.

18.
Analyst ; 144(20): 6108-6117, 2019 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-31532409

RESUMO

There is an increasing urge to investigate facile solutions for monitoring biotoxins, which are a major concern in both the food safety and the anti-terrorism fields. Current techniques, such as immunochromatographic tests (ICT), enzyme-linked immunosorbent assay (ELISA) and mass spectrometry, are still insufficient to satisfy the needs for fast, label-free, and ultra-sensitive detection. Herein, a single-molecular, label-free detection method based on atomic force microscopy was employed to solve the abovementioned problem via a photo-induced force spectrum; typically, three important biotoxins, i.e. abrin toxin (ABR), ricin toxin (RT) and Clostridium perfringens exotoxin (ETX), were used for the demonstration of single molecule detection. The photo-induced force spectrum could be successfully obtained for each of the single protein particles with molecular weights down to 30 kDa. Furthermore, principal component analysis (PCA) was applied for each protein, resulting in a standard PCA identification database. Then, individual components in a mixture of these toxin proteins were well distinguished from each other via matching with the as-built database. Using this strategy, PiFM not only could be used as a powerful tool for single protein detection, but could also be used as a potential tool in protein structural analysis.

19.
Artigo em Inglês | MEDLINE | ID: mdl-31556184

RESUMO

In the chicken small intestine, glucose is mainly transported by the apically located sodium/glucose cotransporter 1 (SGLT1) and the basolaterally located glucose transporter 2 (GLUT2). Fructose is transported by the apically located glucose transporter 5 (GLUT5) and similarly by GLUT2. During the early post-hatching period, the intestinal villus surface area (VSA) should be considered as an important factor related to the monosaccharide absorption capacity. Our objective here was to study intestinal monosaccharide absorption by analyzing the effects of age, diet, and breed on monosaccharide transporters and the VSA. The mRNA expression patterns of SGLT1, GLUT2 and GLUT5 genes in broiler and layer chickens were measured from the day of hatching to day 28 using the absolute quantitative real-time PCR. Both the intestinal mRNA expression levels of these genes and the VSA were affected by age. The mRNA expression levels of SGLT1 and GLUT2 were significantly increased from day 1 to day 3 and then decreased from day 3 to day 28. The expression levels of GLUT5 decreased from day 1 to day 7. The broiler chickens VSAs were significantly larger than those of the layer chickens from days 7 to 28. The effect of diet on the gene expression patterns of these monosaccharide transporters and the VSA were not significant. Our results suggest that the expression levels of these monosaccharide transporters are increased rapidly at the beginning of intestinal growth to meet the demands for monosaccharides to support the fast growth of the chick before day 7. As intestinal maturation and VSA increased, the expression levels of these monosaccharide genes decreased to a certain expression level to maintain the intestinal transport capacity and the absorption balance of all other nutrients.

20.
Materials (Basel) ; 12(15)2019 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-31390783

RESUMO

In the past ten years, extensive research has witnessed the rapid development of perovskite solar cells (PSCs) and diversified preparation processing craft. At present, the most widely used methods of preparing perovskite solar cells are the one-step method and the two-step method. The main work of this paper is to study the effect of the solution deposition process on the quality of perovskite thin films, as well as modulating majority charge carrier types. Perovskite film was prepared in air by designing different processes, which were then adequately analyzed with corresponding methods. It was demonstrated that the preparation process plays a crucial role in modulating the type of majority carrier and in achieving high-quality perovskite thin film. The one-step prepared perovskite layer is enriched in MA+, leading to a P type majority carrier type thin film. The two-step prepared perovskite layer is enriched in Pb2+, leading to a N type majority carrier type thin film. In addition, we found that the one-step method caused PbI2 residue due to component segregation, which seriously affects the interface and film quality of the perovskite layer. This work aims to modulate the majority carrier type of perovskite film through different preparation processes, which can lay the foundation for the study of homojunction perovskite solar cells to improve the device performance of PSCs.

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