564 research outputs found
The Formation of Carbon Microcoils Having the Coil-Type Overall Geometry
Carbon microcoils could be synthesized using a thermal chemical vapor deposition process in which C2H2/H2 is used as the source gas and SF6 as an additive gas. We investigated the formation of carbon microcoils as a function of reaction time to study the growth mechanism of coil-type carbon microcoils, particularly under long reaction time. After the first 5 min of the reaction, wave-like carbon nanocoils were formed along with carbon microcoils at certain positions on the sample. An increase in reaction time (60 min) led to the formation of double helix-type carbon microcoils. Further increase in the reaction time (120 min) led to the formation of twist-type carbon microcoils with occasional growth of the coil-type carbon microcoils on the sample. However, at the longest reaction time (180 min) investigated in this work, we observed a decrease in the density of the carbon microcoils. Based on these results, we determine the optimal reaction time for the growth of double helix-type carbon microcoils and suggest the growth mechanism of the coil-type carbon microcoils with a focus on long reaction time
Hybrid Quantum Dot-Organic Solar Cells by Solution Processing
Department of Energy EngineeringEnvironmental cleaned renewable energy resources such as solar energy have gained significant attention because of the continual enhancement in worldwide energy requirement. A variety of technologies have been developed to make the best use of solar energy. For instance, solar cells based inorganic materials such as silicon wafer can convert solar energy directly to an electricity energy, however inorganic materials are expensive to manufacture, and thus unattractive for general use. Therefore, many researchers have focused on the low cost and easy processing strategies are underway to confirm the materials and solar cells device architectures that are inexpensive efficient compared to inorganic solar cells such as silicon solar cells.
Recently, solution processing thin film solar cells is highlighted and many researchers working on this field. Therefore, conjugated polymer based on the solar cells is rapidly growth and achieved power conversion efficiency (PCE) over 10% in single junction. And quantum dot solar cells (QDSCs) reported over 8% PCE at short period time.
Here, I present positive effect on combination in the organic and quantum dot (QD) for solar cells application with all solution processing. First, The effect of poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) as a buffer layer was investigated in PSCs. Four different types of PEDOT:PSS were used: PH, PH500 and their DMSO-doped counterparts. The efficiency of PSCs was independent of the electric conductivity of the buffer layer as a bulk property. Second, the effect of ionic liquid molecules (ILMs) in QD-organic hybrid solar cells. The insertion of a ILMs layer between PbS QD and Phenyl-C61-butyric acid methyl ester (PCBM) can shift the band edge of the PCBM closer to the vacuum level of PbS. Owing to this new architecture, improvements in device performance were achieved. Third, new technique for preparing inverted colloidal QDSCs using layer-by-layer processed PbS QD and a ZnO layer formed via the solution-phase decomposition of diethyl zinc directly on the PbS film. The inverted QDSCs enhanced in device characteristics stem from constructive optical interference in the absorbing PbS QD layer, as well as outstanding diode characteristics arising from a superior PbS/ZnO junction achieved substantial improvements in short-circuit current, open circuit voltage, fill factor and PCE relative to a control device. Fourth, new types of architecture of hybrid QD-organic solar cells (by introducing PbS QD layer as performing role of photo sensitized layer to achieve high Jsc and PCE using NIR region up to 1100 nm from PbS QD light absorbed.ope
Recommended from our members
Altered expression of norepinephrine transporter and norepinephrine in human placenta cause pre-eclampsia through regulated trophoblast invasion
Objective: We investigated the norepinephrine transporter (NET) expression in normal and pre-eclamptic placentas and analyzed the invasion activity of trophoblastic cells based on norepinephrine (NE)-NET regulation. Methods: NET and NE expression levels were examined by western blot and enzyme-linked immunosorbent assay, respectively. Trophoblast invasion activity, depending on NE-NET regulation, was determined by NET-small interfering RNA (siRNA) and NET transfection into the human extravillous trophoblast cells with or without NE treatment and invasion rates were analyzed by zymography and an invasion assay. Results: NET mRNA was expressed at a low level in pre-eclamptic placentas compared with normal placentas and NE concentration in maternal plasma increased significantly in pre-eclamptic women compared to normal pregnant women (p<0.05). NET gene upregulation and NE treatment stimulated trophoblast cell invasion up to 2.5-fold (p<0.05) by stimulating matrix metalloproteinase-9 activity via the phosphoinositol-3-kinase/AKT signaling pathway, whereas NET-siRNA with NE treatment reduced invasion rates. Conclusion: NET expression is reduced by inadequate regulation of NE levels during placental development. This suggests that a complementary balance between NET and NE regulates trophoblast cell invasion activities during placental development
Nuclear structure in Parity Doublet Model
Using an extended parity doublet model with the hidden local symmetry, we
study the properties of nuclei in the mean field approximation to see if the
parity doublet model could reproduce nuclear properties and also to estimate
the value of the chiral invariant nucleon mass preferred by nuclear
structure. We first determined our model parameters using the inputs from free
space and from nuclear matter properties. Then, we study some basic nuclear
properties such as the nuclear binding energy with several different choices of
the chiral invariant mass. We observe that our results, especially the nuclear
binding energy, approach the experimental values as is increased until
MeV and start to deviate more from the experiments afterwards with
larger than MeV, which may imply that MeV is
preferred by some nuclear properties.Comment: 8 pages, 2 figure
Efficacy of quick Sequential Organ Failure Assessment with lactate concentration for predicting mortality in patients with community-acquired pneumonia in the emergency department
Objective Community-acquired pneumonia (CAP) is a major cause of sepsis, and sepsis-related acute organ dysfunction affects patient mortality. Although the quick Sequential Organ Failure Assessment (qSOFA) is a new screening tool for patients with suspected infection, its predictive value for the mortality of patients with CAP has not been validated. Lactate concentration is a valuable biomarker for critically ill patients. Thus, we investigated the predictive value of qSOFA with lactate concentration for in-hospital mortality in patients with CAP in the emergency department (ED). Methods From January 2015 to June 2015, 443 patients, who were diagnosed with CAP in the ED, were retrospectively analyzed. We defined high qSOFA or lactate concentrations as a qSOFA score ≥2 or a lactate concentration >2 mmol/L upon admission at the ED. The primary outcome was all-cause in-hospital mortality. Results Among the 443 patients, 44 (9.9%) died. Based on the receiver operating characteristic (ROC) analysis, the areas under the curves for the prediction of mortality were 0.720, 0.652, and 0.686 for qSOFA, CURB-65 (confusion, urea, respiratory rate, blood pressure, and age), and Pneumonia Severity Index, respectively. The area under the ROC curve of qSOFA was lower than that of SOFA (0.720 vs. 0.845, P=0.004). However, the area under the ROC curve of qSOFA with lactate concentration was not significantly different from that of SOFA (0.828 vs. 0.845, P=0.509). The sensitivity and specificity of qSOFA with lactate concentration were 71.4% and 83.2%, respectively. Conclusion qSOFA with lactate concentration is a useful and practical tool for the early prediction of in-hospital mortality among patients with CAP in the ED
Solution-processed CdS transistors with high electron mobility
Solution-processed CdS field effect transistors (FETs) and solar cells are demonstrated via spin-coating and thermal annealing of soluble cadmium thiolate compounds. The synthesis is carried out in one simple step using cadmium oxide and tertiary alkane thiols. The cadmium thiolates are soluble in organic solvents such as chloroform and may be spin-coated, like organic semiconductors, to form thin films. The cadmium thiolate films decompose rapidly at 300 ??C to yield semiconducting cadmium sulfide films. FETs are easily fabricated using these films and exhibit electron mobilities of up to 61 cm2 V -1 s-1, which compare favourably to FETs prepared from other solution-processed materials such as organic semiconductors, inorganic nanoparticles or chalcogenide films. Initial attempts to prepare hybrid bilayer solar cells were successfully realized by spin-coating a p-type semiconducting polymer layer on top of the n-type CdS film. These devices show significant photocurrent response from both the CdS and polymer layers, indicating that the CdS films are able to participate in photo-induced electron transfer from the polymer to the CdS layer as well as photo-induced hole transfer from CdS to the polymer layer.close2
Towards optimization of P3HT:bisPCBM composites for highly efficient polymer solar cells
The optimization of the polymer solar cells based on regioregular poly(3-hexylthiophene) (P3HT) and the bisadduct of phenyl C(61)-butyric acid methyl ester (bisPCBM) is studied thoroughly as a role of solvent-annealing effect as well as different concentration of bisPCBM. In the case of P3HT: bisPCBM of 1 : 0.8 w/w, more balanced electron and hole mobilities are observed, resulting in better performance of the solar cells. Under the best balance conditions such as P3HT: bisPCBM of 1 : 0.8 w/w, the solvent annealing is employed to further clarify the optimization of the devices. Such a treatment leads to the formation of crystalline P3HT domains in the blend films, which is determined by X-ray diffraction, UV-vis spectroscopy, and atomic force microscopy. From our experiment, one can conclude that the best power conversion efficiency of 3.75% is achieved in a layered structure of P3HT: bisPCBM of 1 : 0.8 w/w for a solvent-annealing time of 24 h.close201
- …