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1.
Environ Sci Technol ; 58(17): 7279-7290, 2024 Apr 30.
Article in English | MEDLINE | ID: mdl-38629869

ABSTRACT

Exposure to hexavalent chromium damages genetic materials like DNA and chromosomes, further elevating cancer risk, yet research rarely focuses on related immunological mechanisms, which play an important role in the occurrence and development of cancer. We investigated the association between blood chromium (Cr) levels and genetic damage biomarkers as well as the immune regulatory mechanism involved, such as costimulatory molecules, in 120 workers exposed to chromates. Higher blood Cr levels were linearly correlated with higher genetic damage, reflected by urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) and blood micronucleus frequency (MNF). Exploratory factor analysis revealed that both positive and negative immune regulation patterns were positively associated with blood Cr. Specifically, higher levels of programmed cell death protein 1 (PD-1; mediated proportion: 4.12%), programmed cell death ligand 1 (PD-L1; 5.22%), lymphocyte activation gene 3 (LAG-3; 2.11%), and their constitutive positive immune regulation pattern (5.86%) indirectly positively influenced the relationship between blood Cr and urinary 8-OHdG. NOD-like receptor family pyrin domain containing 3 (NLRP3) positively affected the association between blood Cr levels and inflammatory immunity. This study, using machine learning, investigated immune regulation and its potential role in chromate-induced genetic damage, providing insights into complex relationships and emphasizing the need for further research.


Subject(s)
Chromates , Machine Learning , Humans , Cross-Sectional Studies , Environmental Pollutants , Male , DNA Damage , Adult , Female , Middle Aged , Biomarkers
2.
Molecules ; 29(3)2024 Feb 03.
Article in English | MEDLINE | ID: mdl-38338452

ABSTRACT

The efficient synthesis of nanosheets containing two metal ions is currently a formidable challenge. Here, we attempted to dope lanthanide-based bimetals into porphyrin-based metal-organic skeleton materials (MOFs) by microwave-assisted heating. The results of the EDX, ICP, and XPS tests show that we have successfully synthesized porphyrin-based lanthanide bimetallic nanosheets (Tb-Eu-TCPP) using a household microwave oven. In addition, it is tested and experimentally evident that these nanosheets have a thinner thickness, a larger BET surface area, and higher photogenerated carrier separation efficiency than bulk porphyrin-based bimetallic materials, thus exhibiting enhanced photocatalytic activity and n-type semiconductor properties. Furthermore, the prepared Tb-Eu-TCPP nanomaterials are more efficient in generating single-linear state oxygen under visible light irradiation compared to pristine monometallic nanosheets due to the generation of bimetallic nodes. The significant increase in catalytic activity is attributed to the improved separation and transfer efficiency of photogenerated carriers. This study not only deepens our understanding of lanthanide bimetallic nanosheet materials but also introduces an innovative approach to improve the photocatalytic performance of MOFs.

3.
Sci Rep ; 14(1): 17783, 2024 Aug 01.
Article in English | MEDLINE | ID: mdl-39090211

ABSTRACT

The addition of polymer fibers to cemented paste backfill (CPB) has shown promise in enhancing mechanical properties, although it also introduces changes in rheological characteristics. This study aimed to investigate the influence of different types of polymer fibers, namely virgin commercial polypropylene fiber (CPPF), recycled tire polymer fiber (RTPF), and recycled tire rubber fiber (RF), on the rheological properties of CPB mixtures through an experimental program, and provide design references for CPB pipeline transport. The results revealed consistent reductions in bulk density upon the incorporation of polymer fibers into CPB, alongside varying impacts on slump. Specifically, the addition of CPPF had a mild effect, while RTPF caused a continuous decrease in slump, and RF exhibited minimal influence up to a 4% concentration, with substantial effects thereafter. Moreover, the inclusion of fibers led to increases in apparent viscosity parameters, with RTPF inducing the most significant changes, followed by varying responses from CPPF and RF. When using RTPF for CPB reinforcement, emphasis should be placed on enhancing technical indicators related to viscosity such as energy consumption and pipeline wear during pipeline transport. Furthermore, adjustments were necessary to account for flow curve instability resulting from interactions between fibers and the paddle, with the data aligning well with the Bingham model. The addition of fibers, particularly CPPF and RF, primarily influenced plastic viscosity rather than yield stress, underscoring the limitations of slump tests in assessing rheology.

4.
ACS Appl Mater Interfaces ; 16(11): 13525-13533, 2024 Mar 20.
Article in English | MEDLINE | ID: mdl-38467516

ABSTRACT

Flexible electronics have been of great interest in the past few decades for their wide-ranging applications in health monitoring, human-machine interaction, artificial intelligence, and biomedical engineering. Currently, transfer printing is a popular technology for flexible electronics manufacturing. However, typical sacrificial intermediate layer-based transfer printing through chemical reactions results in a series of challenges, such as time consumption and interface incompatibility. In this paper, we have developed a time-saving, wafer-recyclable, eco-friendly, and multiscale transfer printing method by using a stable transferable photoresist. Demonstration of photoresist with various, high-resolution, and multiscale patterns from the donor substrate of silicon wafer to different flexible polymer substrates without any damage is conducted using the as-developed dry transfer printing process. Notably, by utilizing the photoresist patterns as conformal masks and combining them with physical vapor deposition and dry lift-off processes, we have achieved in situ fabrication of metal patterns on flexible substrates. Furthermore, a mechanical experiment has been conducted to demonstrate the mechanism of photoresist transfer printing and dry lift-off processes. Finally, we demonstrated the application of in situ fabricated electrode devices for collecting electromyography and electrocardiogram signals. Compared to commercially available hydrogel electrodes, our electrodes exhibited higher sensitivity, greater stability, and the ability to achieve long-term health monitoring.

5.
Front Oncol ; 14: 1375748, 2024.
Article in English | MEDLINE | ID: mdl-39022587

ABSTRACT

Background: We describe a rare case of giant adrenal calcification as the main cause of sudden onset epigastric pain in a 57-year-old female patient. Case description: Computed tomography (CT) of the whole abdomen in this patient showed calcified foci measuring approximately 7.8 × 5.4 × 7.1 cm in the hepatorenal recess, and no enhancement effect was seen. Secondary causes of adrenal calcification in this patient were ruled out, and a rare diagnosis of a primary giant adrenal calcification was made. Subsequently, the right adrenal gland and calcified mass were completely resected. The calcification did not recur during 6 months of follow up. Conclusions: Although other cases of adrenal calcification of unknown origin have been reported, cases of giant idiopathic adrenal calcification are rare. In this case, huge calcification of the right adrenal gland caused abdominal pain, which disappeared after the mass was excised. The etiology, pathogenesis, clinical symptoms, and prognosis of idiopathic adrenal calcification are still unclear. Additional case reports are needed to gain a better understanding of the diagnosis and treatment of this condition.

6.
Heliyon ; 10(19): e38571, 2024 Oct 15.
Article in English | MEDLINE | ID: mdl-39403540

ABSTRACT

From the molecular to the cellular to the tissue level, vascular aging is regulated by a complex network involving numerous mechanisms and diseases, and our knowledge of any one level is incomplete and biased. To date, due to the diversity and complexity of the influencing factors, no international standard has been established. Therefore, in this study, we aimed to analyze the global research trends and potential hotspots related to vascular aging. We extracted the relevant publications between January 2003 and December 2023 from the Web of Science Core Collection. VOSviewer and CiteSpace software were used to quantitatively and qualitatively analyze the authors, countries, institutions, and journals in the field of vascular aging. The total number of publications on vascular aging between January 2003 and December 2023 was 1044, showing a steady increase. The United States and the University of Oklahoma published the highest number of research papers in the field. Ungvari Zoltan from the University of Oklahoma was the most productive author (47 papers) on vascular aging, specializing in endothelial cell failure, microcirculation, and aging. Burst detection of keywords revealed that endothelial dysfunction and vascular smooth muscle cells had the highest burst strength, suggesting that these are the current research hot spots in vascular aging research. In conclusion, senescence-associated secretory phenotype, reactive oxygen species, genetic instability, and an imbalance of protein homeostasis, trigger an inflammatory response that affects vascular endothelial and smooth muscle cell function, ultimately leading to vascular aging. This research provides insights into recent advances and preventive strategies in the field of vascular aging.

7.
Front Med (Lausanne) ; 11: 1432275, 2024.
Article in English | MEDLINE | ID: mdl-39021826

ABSTRACT

Background: Urolithiasis is a prevalent condition encountered in urology. Over the past decade, its global incidence has been on an upward trajectory; paired with a high recurrence rate, this presents considerable health and economic burdens. Although inflammatory factors are pivotal in the onset and progression of urolithiasis, their causal linkages remain elusive. Method: Mendelian randomization (MR) is predicated upon genome-wide association studies (GWASs). It integrates bioinformatics analyses to reveal causal relationships between exposures and outcomes, rendering it an effective method with minimized bias. Drawing from a publicly accessible GWAS meta-analysis comprising 8,293 samples, we identified 41 genetic variations associated with inflammatory cytokines as instrumental variables. Outcome data on upper urinary tract stones, which included renal and ureteral stones (9,713 cases and 366,693 controls), and lower urinary tract stones, including bladder and urethral stones (1,398 cases and 366,693 controls), were derived from the FinnGen Consortium R9 dataset. By leveraging the bidirectional MR methodology, we aimed to decipher the causal interplay between inflammatory markers and urolithiasis. Results: Our study comprehensively elucidated the association between genetic inflammatory markers and urolithiasis via bidirectional Mendelian randomization. Post-MR analysis of the 41 genetic inflammation markers revealed that elevated levels of circulating interleukin-2 (IL-2) (OR = 0.921, 95% CI = 0.848-0.999) suggest a reduced risk for renal stone disease, while heightened stem cell growth factor beta (SCGF-ß) (OR = 1.150, 95% CI = 1.009-1.310) and diminished macrophage inflammatory protein 1 beta (MIP-1ß) (OR = 0.863, 95% CI = 0.779-0.956) levels suggest an augmented risk for lower urinary tract stones. Furthermore, renal stone disease appeared to elevate IL-2 (ß = 0.145, 95% CI = 0.013-0.276) and cutaneous T cell-attracting chemokine (CTACK) (ß = 0.145, 95% CI = 0.013-0.276) levels in the bloodstream, whereas lower urinary tract stones were linked to a surge in interleukin-5 (IL-5) (ß = 0.142, 95% CI = 0.057-0.226), interleukin-7 (IL-7) (ß = 0.108, 95% CI = 0.024-0.192), interleukin-8 (IL-8) (ß = 0.127, 95% CI = 0.044-0.210), growth regulated oncogene alpha (GRO-α) (ß = 0.086, 95% CI = 0.004-0.169), monokine induced by interferon-gamma (MIG) (ß = 0.099, 95% CI = 0.008-0.191) and macrophage inflammatory protein 1 alpha (MIP-1α) (ß = 0.126, 95% CI = 0.044-0.208) levels. Conclusion: These discoveries intimate the instrumental role of IL-2 in the onset and progression of upper urinary tract stones. SCGF-ß and MIP-1ß influence the development of lower urinary tract stones. Urolithiasis also impacts the expression of cytokines such as IL-2, CTACK, IL-5, IL-7, IL-8, GRO-α, MIG, and MIP-1α. There is a pressing need for further investigation to ascertain whether these biomarkers can be harnessed to prevent or treat urolithiasis.

8.
J Am Chem Soc ; 135(32): 11696-9, 2013 Aug 14.
Article in English | MEDLINE | ID: mdl-23895560

ABSTRACT

A photostable p-type NiO photocathode based on a bifunctional cyclometalated ruthenium sensitizer and a cobaloxime catalyst has been created for visible-light-driven water reduction to produce H2. The sensitizer is anchored firmly on the surface of NiO, and the binding is resistant to the hydrolytic cleavage. The bifunctional sensitizer can also immobilize the water reduction catalyst. The resultant photoelectrode exhibits superior stability in aqueous solutions. Stable photocurrents have been observed over a period of hours. This finding is useful for addressing the degradation issue in dye-sensitized photoelectrochemical cells caused by desorption of dyes and catalysts. The high stability of our photocathodes should be important for the practical application of these devices for solar fuel production.

9.
Langmuir ; 28(1): 950-6, 2012 Jan 10.
Article in English | MEDLINE | ID: mdl-22085223

ABSTRACT

We present a systematic investigation of the fundamental effects of an atomically deposited alumina (AlO(x)H(y)) onto the NiO films in p-type dye-sensitized solar cells (p-DSCs). With P1 as the sensitizing dye and 0.1 M I(2) and 1.0 M LiI in 3-methoxypropionitrile as the electrolyte, one atomic layer deposition (ALD) cycle of alumina was used to achieve a 74% increase in the overall conversion efficiency of a NiO-based DSC. The open circuit voltage of the cells increased from 0.11 to 0.15 V, and the short circuit current density increased from 0.83 to 0.95 mA/cm(2). Adsorption isotherm studies were performed to show that the amount of dye adsorbed on the NiO-alumina film is slightly lower than the amount adsorbed on the nontreated NiO film. The increased J(sc) was therefore assigned to the increased efficiency of carrier collection at the semiconductor-FTO interface. Our study of the photocurrent onset potentials of NiO and NiO-alumina films with the chopped light measurement technique showed no definitive difference in the onset potential values. However, the DSCs based on NiO-alumina showed a higher recombination resistance value from the electrochemical impedance studies and a higher diode ideality factor from the V(oc) versus ln(light intensity) plots as compared to the DSCs based on untreated NiO. It has thus been established that the increase in V(oc) upon alumina treatment arises due to a higher resistance for electron-hole recombination across NiO surface locally.

10.
Zhong Yao Cai ; 35(8): 1326-30, 2012 Aug.
Article in Zh | MEDLINE | ID: mdl-23320368

ABSTRACT

OBJECTIVE: To optimize the extraction process for Qingrejiedu oral liquid with synthesizing multiple guidelines grading method. METHODS: Used the extraction rate of baicalin and geniposide comprehensive contribution rate variance as index, extraction time and added water were as factors, central composite design was used for optimization of extraction process, and forecasting analysis parameters. RESULTS: The optimal extraction process was as follows: extraction time 139 min, added water 13 times, grading index was 0.768. CONCLUSION: Synthesizing multiple guidelines grading method is ideal for multi-component extraction experiment design, its easy application, the forecast is good and so on.


Subject(s)
Drugs, Chinese Herbal/isolation & purification , Flavonoids/isolation & purification , Iridoids/isolation & purification , Plants, Medicinal/chemistry , Technology, Pharmaceutical/methods , Administration, Oral , Chromatography, High Pressure Liquid/methods , Drugs, Chinese Herbal/chemistry , Flavonoids/analysis , Gardenia/chemistry , Iridoids/analysis , Quality Control , Reproducibility of Results , Scutellaria baicalensis/chemistry , Technology, Pharmaceutical/standards
11.
Front Immunol ; 13: 934494, 2022.
Article in English | MEDLINE | ID: mdl-35911707

ABSTRACT

This study aims to investigate the immune and epigenetic mutational landscape of necroptosis in lung adenocarcinoma (LUAD), identify novel molecular phenotypes, and develop a prognostic scoring system based on necroptosis regulatory molecules for a better understanding of the tumor immune microenvironment (TIME) in LUAD. Based on the Cancer Genome Atlas and Gene Expression Omnibus database, a total of 29 overlapped necroptosis-related genes were enrolled to classify patients into different necroptosis phenotypes using unsupervised consensus clustering. We systematically correlated the phenotypes with clinical features, immunocyte infiltrating levels, and epigenetic mutation characteristics. A novel scoring system was then constructed, termed NecroScore, to quantify necroptosis of LUAD by principal component analysis. Three distinct necroptosis phenotypes were confirmed. Two clusters with high expression of necroptosis-related regulators were "hot tumors", while another phenotype with low expression was a "cold tumor". Molecular characteristics, including mutational frequency and types, copy number variation, and regulon activity differed significantly among the subtypes. The NecroScore, as an independent prognostic factor (HR=1.086, 95%CI=1.040-1.133, p<0.001), was able to predict the survival outcomes and show that patients with higher scores experienced a poorer prognosis. It could also evaluate the responses to immunotherapy and chemotherapeutic efficiency. In conclusion, necroptosis-related molecules are correlated with genome diversity in pan-cancer, playing a significant role in forming the TIME of LUAD. Necroptosis phenotypes can distinguish different TIME and molecular features, and the NecroScore is a promising biomarker for predicting prognosis, as well as immuno- and chemotherapeutic benefits in LUAD.


Subject(s)
Adenocarcinoma of Lung , Lung Neoplasms , DNA Copy Number Variations , Humans , Lung Neoplasms/pathology , Necroptosis/genetics , Phenotype , Tumor Microenvironment/genetics
12.
Oxid Med Cell Longev ; 2022: 8297011, 2022.
Article in English | MEDLINE | ID: mdl-35313641

ABSTRACT

Purpose: This study is aimed at systematically analyzing the expression, function, and prognostic value of six transmembrane epithelial antigen of the prostate 1 (STEAP1) in various cancers. Methods: The expressions of STEAP1 between normal and tumor tissues were analyzed using TCGA and GTEx. Clinicopathologic data was collected from GEPIA and TCGA. Prognostic analysis was conducted by Cox proportional hazard regression and Kaplan-Meier survival. DNA methylation, mutation features, and molecular subtypes of cancers were also investigated. The top-100 coexpressed genes with STEAP1 were involved in functional enrichment analysis. ESTIMATE algorithm was used to analyze the correlation between STEAP1 and immunity value. The relationships of STEAP1 and biomarkers including tumor mutational burden (TMB), microsatellite instability (MSI), and stemness score as well as chemosensitivity were also illustrated. Results: Among 33 cancers, STEAP1 was overexpressed in 19 cancers such as cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC), colon adenocarcinoma, and lymphoid neoplasm diffuse large B cell lymphoma while was downregulated in 5 cancers such as adrenocortical carcinoma, breast invasive carcinoma (BRCA), and kidney chromophobe renal cell carcinoma. STEAP1 has significant prognostic relationships in multiple cancers. 15 cancers exhibited differences of DNA methylation including bladder urothelial carcinoma, BRCA, and CESC. STEAP1 expression was positively correlated to immune molecules especially in thyroid carcinoma and negatively especially in uveal melanoma. STEAP1 was associated with TMB and MSI in certain cancers. In addition, STEAP1 was connected with increased chemosensitivity of drugs such as trametinib and pimasertib. Conclusions: STEAP1 was an underlying target for prognostic prediction in different cancer types and a potential biomarker of TMB, MSI, tumor microenvironment, and chemosensitivity.


Subject(s)
Antigens, Neoplasm , Carcinoma, Transitional Cell , Oxidoreductases , Urinary Bladder Neoplasms , Antigens, Neoplasm/metabolism , Carcinoma, Transitional Cell/metabolism , Carcinoma, Transitional Cell/pathology , Humans , Oxidoreductases/metabolism , Prognosis , Tumor Microenvironment/genetics , Urinary Bladder Neoplasms/pathology
13.
Chemistry ; 17(8): 2479-91, 2011 Feb 18.
Article in English | MEDLINE | ID: mdl-21264958

ABSTRACT

The synthesis, one-photon photophysics and two-photon absorption (2PA) of three dipolar D-π-A 4-[9,9-di(2-ethylhexyl)-7-diphenylaminofluoren-2-yl]-2,2':6',2''-terpyridine and their platinum chloride complexes with different linkers between the donor and acceptor are reported. All ligands exhibit (1)π,π* transition in the UV and (1)π,π*/(1)ICT (intramolecular charge transfer) transition in the visible regions, while the complexes display a lower-energy (1)π,π*/(1)CT (charge transfer) transition in the visible region in addition to the high-energy (1)π,π* transitions. All ligands and the complexes are emissive at room temperature and 77 K, with the emitting excited state assigned as the mixed (1)π,π* and (1)CT states at RT. Transient absorption from the ligands and the complexes were observed. 2PA was investigated for all ligands and complexes. The two-photon absorption cross-sections (σ(2)) of the complexes (600-2000 GM) measured by Z-scan experiment are much larger than those of their corresponding ligands measured by the two-photon induced fluorescence method. The ligand and the complex with the ethynylene linker show much stronger 2PA than those with the vinylene linker.


Subject(s)
Fluorenes/chemistry , Models, Molecular , Organoplatinum Compounds/chemical synthesis , Photons , Platinum Compounds/chemistry , Pyridines/chemistry , Fluorenes/chemical synthesis , Luminescence , Molecular Structure , Organoplatinum Compounds/chemistry , Photochemical Processes , Pyridines/chemical synthesis
14.
Inorg Chem ; 50(3): 705-7, 2011 Feb 07.
Article in English | MEDLINE | ID: mdl-21204549

ABSTRACT

Three platinum(II) terpyridylacetylide charge-transfer complexes possessing a lone ancillary ligand systematically varied in phenylacetylide π-conjugation length, [Pt((t)Bu(3)tpy)([C≡CC(6)H(4)](n)H)]ClO(4) (n = 1-3), are evaluated as photosensitizers (PSs) for visible-light-driven (λ > 420 nm) hydrogen production in the presence of a cobaloxime catalyst and the sacrificial electron donor triethanolamine (TEOA). Excited-state reductive quenching of the PS by TEOA produces PS(-) (k(q) scales with the driving force as 1 > 2 > 3), enabling thermal electron transfer to the cobalt catalyst. The initial H(2) evolution is directly proportional to the incident photon flux and visible-light harvesting capacity of the sensitizer, 3 > 2 > 1. The combined data suggest that PSs exhibiting attenuated bimolecular reductive quenching constants with respect to the diffusion limit can overcome this deficiency through improved light absorption in homogeneous H(2)-evolving compositions.

15.
Inorg Chem ; 49(4): 1337-46, 2010 Feb 15.
Article in English | MEDLINE | ID: mdl-20092284

ABSTRACT

Two back-to-back terpyridine ligands using fluorenyl as bridging group (1-L and 2-L) and their corresponding dinuclear platinum(II) complexes (1 and 2) were synthesized and characterized. Their electronic absorption, photoluminescence, and the triplet transient difference absorption were systematically investigated. Both ligands possess intense (1)pi,pi* absorption in the UV region, and they exhibit structured (1)pi,pi* fluorescence around 400 nm. With addition of p-toluenesulfonic acid to the ligands, both the absorption band and the emission band are red-shifted because of the increased electron-withdrawing ability of the protonated terpyridines and possible mixture of some intraligand charge transfer (ILCT) character. For complexes 1 and 2, they both exhibit broad and strong absorption between 400 and 500 nm, which is assigned as the (1)pi,pi*/(1)ILCT/(1)MLCT (metal-to-ligand charge transfer) transition. The involvement of (1)ILCT in the lowest excited state is evident by the acid titration experiment of the ligands. At room temperature, the complexes exhibit dual emission that admixes fluorescence and phosphorescence from the (1,3)pi,pi*/(1,3)ILCT/(1,3)MLCT states. The assignment of the emitting states is based on the distinct emission lifetimes, different sensitivity to oxygen quenching, and different temperature dependency. Both complexes exhibit emission at 77 K, which is assigned as the mixture of (3)pi,pi*/(3)MLCT. 1 and 2 also exhibit two triplet excited-state absorption bands in the visible to the NIR region, which are tentatively attributed to the (3)pi,pi* and (3)MLCT/(3)ILCT state. In addition, the connection pattern between the fluorenyl component and the terpyridyl components influences the excited-state characteristics of both the ligands and the complexes. Ligand 1-L and its corresponding platinum complex 1 that have the triplet bond connection between the fluorenyl and terpyridyl components exhibit a red-shifted low-energy absorption band, an emission band, and a transient absorption band compared to ligand 2-L and complex 2 that have the fluorenyl directly attached to terpyridyl components. These differences could be rationalized by the enhanced conjugation between the fluorenyl and terpyridyl components in 1-L and 1 because of the better coplanarity induced by the triple bond.


Subject(s)
Electrons , Metals/chemistry , Photochemistry/methods , Platinum/chemistry , Benzenesulfonates/chemistry , Crystallization , Electrochemistry/methods , Ligands , Luminescence , Models, Chemical , Molecular Structure , Structure-Activity Relationship , Temperature
16.
J Phys Chem Lett ; 10(5): 953-959, 2019 Mar 07.
Article in English | MEDLINE | ID: mdl-30764609

ABSTRACT

The electronic structure of a series of bottom-up synthesized graphene quantum dots (GQDs) smaller than 2 nm was investigated by spectroelectrochemistry, yielding insights not previously available from ensemble-level studies. The results show that for the strongly confined GQDs the dependence of the band gap on the GQD size deviates from the prediction of the standard Dirac Fermion model but agrees well with the models explicitly accounting for the electron-electron and electron-hole interactions. The HOMO/LUMO energy levels are found to be distributed nearly symmetrically around the 0 V value versus normal hydrogen electrode (NHE), becoming more positive/negative, respectively, with increasing GQD size. The exciton binding energies are found to follow power dependence on the number of carbon atoms per GQD, with the experimental values falling within the range of ∼0.1 to ∼0.6 eV. Given the broad accessibility of the described experimental tools and methods, our work opens a path to a more systematic examination of quantum confinement effects in GQDs.

17.
Nanoscale ; 11(35): 16571-16581, 2019 Sep 21.
Article in English | MEDLINE | ID: mdl-31460557

ABSTRACT

Graphene quantum dots (GQDs) have attracted significant interest as synthetically tunable optoelectronic and photonic materials that can also serve as model systems for understanding size-dependent behaviors of related graphene structures such as nanoribbons. We present a Raman spectroscopy study of bottom-up synthesized GQDs with lateral dimensions between 0.97 to 1.62 nm, well-defined (armchair) edge type, and fully benzenoid structures. For a better understanding of observed size-dependent trends, the study is extended to larger graphene structures including nano-graphene platelets (>25 nm) and large-area graphene. Raman spectra of GQDs reveal the presence of D and G bands, as well as higher order modes (2D, D + G, and 2G). The D and G band frequencies and intensity were found to increase as GQD size increases, while higher order modes (2D, D + G, and 2G) also increased in intensity and became more well-defined. The integrated intensity ratios of D and G bands (ID/IG) increase as the size of the GQDs approaches 2 nm and rapidly decrease for larger graphene structures. We present a quantitative comparison of ID/IG ratios for the GQDs and for defects introduced into large area graphenes through ion bombardment, for which inter-defect distances are comparable to the sizes of GQDs studied here. Close agreement suggests the ID/IG ratio as a size diagnostic for other nanographenes. Finally, we show that Raman spectroscopy is also a good diagnostic tool for monitoring the formation of bottom-up synthesized GQDs.

18.
Small ; 4(8): 1168-75, 2008 Aug.
Article in English | MEDLINE | ID: mdl-18574800

ABSTRACT

The tumor-inhibitory effect of C60(OH)x was tested on the murine H22 hepatocarcinoma model. Doses of 0.2 and 1.0 mg kg(-1) body weight both showed significant antitumor activity with tumor inhibition rates of 31.9 and 38.4%, respectively, when mice were treated for 17 consecutive days. The damnification of liver was prominently reduced. Furthermore, histological examination indicated that an envelope of fibroblasts and lymphocytes was formed surrounding tumor tissues in the C60(OH)x-treated group, which inhibited the infiltration of tumor to the neighboring normal skeleton muscle tissues. To understand the antitumor mechanism, the immunomodulatory activity of C60(OH)x was investigated. The results indicate that C60(OH)x enhances the phagocytosis of peritoneal macrophages and elevates the activity of arginase and acid phosphatase in vivo. The tumor necrosis factor alpha production of C60(OH)x-treated macrophages also increases in vitro. These results suggest that C60(OH)x can enhance the innate immunity of tumor-bearing mice, and therefore inhibits growth of the tumor.


Subject(s)
Antineoplastic Agents/pharmacology , Carcinoma, Hepatocellular/drug therapy , Fullerenes/pharmacology , Growth Inhibitors/pharmacology , Immunologic Factors/pharmacology , Liver Neoplasms, Experimental/drug therapy , Animals , Carcinoma, Hepatocellular/immunology , Carcinoma, Hepatocellular/pathology , Cell Line, Tumor , Female , Liver Neoplasms, Experimental/pathology , Macrophages, Peritoneal/drug effects , Macrophages, Peritoneal/immunology , Male , Mice , Mice, Inbred Strains
19.
Inorg Chem ; 47(17): 7599-607, 2008 Sep 01.
Article in English | MEDLINE | ID: mdl-18661973

ABSTRACT

A series of new square-planar 4'-(5'''-R-pyrimidyl)-2,2':6',2''-terpyridyl platinum(II) phenylacetylide complexes ( 1a- 5a) bearing different substituents (R = H, OEt, Ph, Cl, CN) on the pyrimidyl ring have been synthesized and characterized. The electronic absorption, photoluminescence, and triplet transient difference absorption spectra were investigated. All of the complexes exhibit broad, moderately strong absorption between 400 and 500 nm that can be tentatively assigned to the metal-to-ligand charge transfer ( (1)MLCT) transition, possibly mixed with some ligand-to-ligand charge transfer ( (1)LLCT) character. Photoluminescence arising from the (3)MLCT state was observed both in fluid solutions at room temperature and in a rigid matrix at 77 K. The (1)MLCT/ (1)LLCT absorption bands and the (3)MLCT emission bands for 1a- 5a red-shift in comparison to those of the corresponding 4'-toly-2,2':6',2''-terpyridyl platinum(II) phenylacetylide complex. In addition, the energies of the (1)MLCT/ (1)LLCT absorption and the (3)MLCT emission bands exhibit a linear correlation with the Hammett constant (sigma p) of the 5'''-substituent on the pyrimidyl ring. The lifetime of the (3)MLCT emission at room temperature is governed by the energy gap law. The triplet transient difference absorption spectra of 1a- 5a exhibit a broad absorption band from 500 to 800 nm, and a bleaching band between 420 and 500 nm. Complex 5a, which contains the -CN substituent, exhibits a lower-energy triplet absorption band at 785 nm and a shorter lifetime (130 ns) in CH 3CN than 2a, which has the -OEt substituent, does (lambda T1-Tn (max) = 720 nm, tau T = 660 ns). The triplet excited-state absorption coefficients at the band maxima for 1a- 5a vary from 36 600 L.mol (-1).cm (-1) to 115 090 L.mol (-1).cm (-1), and the quantum yields of the triplet excited-state formation range from 0.19 to 0.66. All complexes exhibit a moderate nonlinear transmission for nanosecond laser pulses at 532 nm. Moreover, these complexes can generate singlet oxygen efficiently in air-saturated CH 3CN solutions, with the singlet oxygen generation quantum yield (Phi Delta) varying from 0.24 to 0.46.

20.
ACS Nano ; 9(4): 4043-9, 2015 Apr 28.
Article in English | MEDLINE | ID: mdl-25768313

ABSTRACT

Polyclic aromatic hydrocarbons also called Graphene Molecules (GMs), with chemical composition C132H36(COOH)2 were synthesized in situ on the surface of transparent nanocrystalline indium tin oxide (nc-ITO) electrodes and their electronic structure was studied electrochemically and spectro-electrochemically. Variations in the potential applied onto the nc-ITO/GM electrodes induce only small changes in the observed current, but they produce dramatic changes in the absorption of the GMs, which are associated with their oxidation and reduction. Analysis of the absorption changes using a modified Nernst equation is used to determine standard potentials associated with the individual charge transfer processes. For the GMs prepared here, these were found to be E1,ox(0) = 0.77 ± 0.01 V and E2,ox(0) = 1.24 ± 0.02 V vs NHE for the first and second oxidation and E1,red(0) = -1.50 ± 0.04 V for the first reduction. The charge transfer processes are found to be nonideal. The nonideality factors associated with the oxidation and reduction processes are attributed to strong interactions between the GM redox centers. Under the conditions of potential cycling, GMs show rapid (seconds) color change with high contrast and stability. An electrochromic application is demonstrated wherein the GMs are used as the optically active component.

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