829 research outputs found
¿Es China capitalista?
No full textInternational audienceEste libro quiere romper el consenso y perturbar algunas certezas. Por ejemplo, sosteniendo que es un error atribuir los logros de la economía china a la supuesta “adhesión” de este país al capitalismo. La conclusión a la que llegan los autores Rémy Herrera y Zhiming Long es que, hoy, el sistema chino no es capitalista –aunque no sin riesgos de desembocar en el capitalismo– sino una forma de socialismo con mercado, en el que la planificación es, todavía, determinante
Spurious OLS Estimators of Detrending Method by Adding a Linear Trend in Difference-Stationary Processes - A Mathematical Proof and its Verification by Simulation
No full textInternational audiencefirst_pagesettingsOrder Article ReprintsOpen AccessArticleSpurious OLS Estimators of Detrending Method by Adding a Linear Trend in Difference-Stationary Processes—A Mathematical Proof and Its Verification by Simulationby Zhiming LONG1,* and Rémy HERRERA21Research Center for College Moral Education, Tsinghua University, 307C Shanzhai Building, Tsinghua University, Beijing 100084, China2CNRS (National Center for Scientific Research)—UMR 8174 Centre d’Économie de la, Maison des Sciences Economiques de l’Université de Paris 1 Panthéon-Sorbonne 106-112 boulevard de l’Hôpital, 75013 Paris, France*Author to whom correspondence should be addressed.Mathematics 2020, 8(11), 1931; https://doi.org/10.3390/math8111931Received: 2 September 2020 / Revised: 23 September 2020 / Accepted: 25 September 2020 / Published: 2 November 2020(This article belongs to the Section Dynamical Systems)Download Browse FiguresVersions NotesAbstractAdding a linear trend in regressions is a frequent detrending method in economic literatures. The traditional literatures pointed out that if the variable considered is a difference-stationary process, then it will artificially create pseudo-periodicity in the residuals. In this paper, we further show that the real problem might be more serious. As the Ordinary Least Squares (OLS) estimators themselves are of such a detrending method is spurious. The first part provides a mathematical proof with Chebyshev’s inequality and Sims–Stock–Watson’s algorithm to show that the OLS estimator of trend converges toward zero in probability, and the other OLS estimator diverges when the sample size tends to infinity. The second part designs Monte Carlo simulations with a sample size of 1,000,000 as an approximation of infinity. The seed values used are the true random numbers generated by a hardware random number generator in order to avoid the pseudo-randomness of random numbers given by software. This paper repeats the experiment 100 times, and gets consistent results with mathematical proof. The last part provides a brief discussion of detrending strategies
A Non-invasive Method for Removing a Non-Deflatable Bladder Catheter.mp4
No full textTitle: A Non-invasive Method for Removing a Non-Deflatable Bladder CatheterJournal: International Urology and NephrologyAuthor: Qing Cheng; Haibo Zhang; Guoren Wang; Zhenxiang Liu; Zhiming BaiCorresponding author: Zhiming BaiE-mail: [email protected] </p
Long-term stability of Au nanoparticle-anchored porous boron-doped diamond hybrid electrode for enhanced dopamine detection
No full textA porous boron-doped diamond (pBDD) was made for immobilizing gold nanoparticles on BDD facets by a special process, wherein methods of magnetron sputtering and thermal catalytic treatment were utilized. Au nanoparticles are seated in the pores of pBDD facets and could be more stable during electrochemical tests. This hybrid structure significantly improved the electrochemical properties due to the introduction of Au nanoparticles and pores, which could increase the specific surface area. The cyclic voltammetry oxidation peak current of the Au/pBDD electrode decreased with an average daily loss of 0.02 μA and maintained approximately 90.1% of its initial value after detecting dopamine once per two days for 30 days, showing an excellent long-term electrochemical stability. In addition, the Au/pBDD electrode exhibited excellent sensitivity for the detection of DA, and the limit of detection was 0.06 μM in a linear concentration range of 0.1 μM–1 mM. This work indicates that the Au/pBDD is an appropriate material for detecting DA in a long-term tests.</p
Nickel-encapsulated carbon nanotubes modified boron doped diamond hybrid electrode for non-enzymatic glucose sensing
No full textA hybrid non-enzymatic glucose sensor made by incorporating boron doped diamond (BDD) film electrode with nickel (Ni)encapsulated carbon nanotubes (CNTs) were facilely fabricated. The CNTs were grown directly on BDD films in the presence of pre-sputtered Ni layer as a catalyst by hot-filament chemical vapor deposition. The morphology and composition of the hybrid structure were assessed by scanning electron microscopy and Raman spectroscopy. As Ni layer thickness increased, the CNTs were less covered on the surface and the length of CNTs increased. The Ni particles were encapsulated into a large number of CNTs. Electrochemical results indicated that this hybrid structure significantly improved the electrochemical performance of BDD due to the increased specific surface area and synergistic effect of Ni and CNTs. The optimized glucose sensor revealed two broad linear range of 1.25 μM - 0.49 mM and 0.49 mM- 6.79 mM, with a high sensitivity of 1642.20 μA mM−1 cm−2 (R2 = 0.9988) and 1374.4 μA mM−1 cm−2 (R2 = 0.9969) respectively. In addition, the hybrid electrode exhibited a low limit of detection which was 1.0 μM (S/N = 3), and good selectivity and stability.</p
Role of Carbon Nanotubes to Enhance the Long-Term Stability of Dye-Sensitized Solar Cells
No full textImproving the long-term stability of dye-sensitized solar cells (DSSCs) is a critical challenge which affects both their technical viability and future large-scale commercialization. Here, we investigate the role of multiwall carbon nanotubes (MWCNTs) in improving the long-term stability of DSSCs by comparing the performance of two series of devices made of (i) bare nanocrystalline TiO2 and (ii) MWCNTs-TiO2 composite anode, which are exposed to continuous simulated sunlight, indoor and ultraviolet (UV) light irradiation. The DSSCs based on the composite anode showed approximately 3 times longer stability compared with the standard device. To understand the degradation mechanisms that underpin these changes in device performance, both devices were characterized using various techniques. The results indicate that the MWCNTs can act as a conductive support, reinforcing the TiO2 nanoparticles’ matrix and offering a directional path to the photoinjected electrons, which enhances electron lifetime and reduces the carrier recombination rate. UV stability measurements demonstrated that MWCNTs can partially absorb and act as a blocking agent for UV light, thereby preventing degradation. The Raman spectra showed that dye desorption was decreased by the addition of MWCNTs. Our results provide a fundamental understanding of photoanode degradation mechanisms under illumination and offer a simple, low-cost, and large-area scalable approach to fabricate solar-energy-conversion devices with long-term stability
Synergistic tailoring of band structure and charge carrier extraction in "green" core/shell quantum dots for highly efficient solar energy conversion
No full textEnvironment-friendly colloidal core/shell quantum dots (QDs) with controllable optoelectronic characteristics are promising building blocks for future commercial solar technologies. Herein, we synergistically tailor the electronic band structure and charge carrier extraction of eco-friendly AgInS2 (AIS)/ZnS core/shell QDs via Mn-alloying and Cu-doping in the core and shell, respectively. It is demonstrated that the Mn-alloying in AIS core can broaden the band gap to facilitate delocalization of photogenerated electrons into the shell and further incor-poration of Cu in the ZnS shell enables the creation of Cu-related states that capture the photogenerated holes from core, thus leading to charge carrier recombination and accelerated transfer of photogenerated electrons in the core/shell QDs. As-prepared Mn-AIS/ZnS@Cu QDs were assembled as light harvesters in a photo-electrochemical (PEC) device for light-driven hydrogen evolution, delivering a maximum photocurrent density of ~ 6.4 mA cm-2 with superior device stability under standard one sun irradiation (AM 1.5G, 100 mW cm(-2)). Our findings highlight that simultaneously engineering the band alignment and charge carrier dynamics of "green " core/shell QDs endow the feasibility to design future high-efficiency and durable solar hydrogen pro-duction systems
Some considerations on China’s long-run economic growth: 1952–2015 from the analysis of factor contributions to that of the profit rate
No full textInternational audienceThis article offers methodological reflexions on China’s long-term economic growth. We first construct time series of physical capital stocks going from 1952, close to the date of formation of the People’s Republic, until 2015, by taking into account the latest yearbooks (I). Then, we test this new database to estimate the contributions of the production factors to GDP growth within the framework of various neoclassical models, highlighting the limitations of the latter (II). After that, an original framework is mobilized, in the spirit of the recent researches provided by Thomas Piketty, who combines mainstream references with components borrowing from Keynesian as well as neoinstitutionalist formalisations. Here, several problems associated with such researches are identified (III). Finally, we move the discussion towards a more promising approach, involving profit rate indicators, to deepen future studies of China’s long-run economic growth (IV)
Simultaneous copper incorporation in core/shell-structured eco-friendly quantum dots for high-efficiency photoelectrochemical hydrogen evolution
No full textThe rational design of elemental incorporation in colloidal eco-friendly core/shell quantum dots (QDs) holds the potential to synergistically tailor their electronic band structure and carrier kinetics for applications in forthcoming “green” and high-efficiency solar energy conversion. Herein, we have conducted simultaneous Cu incorporation in both the core and shell regions of environment-benign AgInSe (AISe)/ZnSe core/shell QDs to realize high-efficiency solar-driven photoelectrochemical (PEC) hydrogen evolution. It is verified that Cu incorporation in AISe core enables an upward shift in the position of the band edge relative to the ZnSe shell, which promoted the electron delocalization and extended the lifetime of exciton. Simultaneously, Cu incorporation in the ZnSe shell further results in the trapping of photoinduced holes from AISe core, leading to a decelerated recombination of carriers. The prepared Cu-AISe/ZnSe:Cu QDs with optimized optoelectronic properties have been successfully employed to fabricate QDs-PEC devices, delivering a maximum photocurrent density of 9.1 mA cm−2 under standard AM 1.5 G illumination (100 mW cm−2). Our findings indicate that synchronous elemental incorporation in eco-friendly core/shell QDs is a promising strategy to achieve future high-performance solar-to-hydrogen conversion systems.Validerad;2024;Nivå 2;2024-02-05 (joosat);Funder: Sichuan Science and Technology Program (2021YFH0054, 2023JDGD0011); National Natural Science Foundation of China (22105031); National Key Research and Development Program of China (2019YFE0121600); Fundamental Research Funds for the Central Universities (2019YFB2203400, ZYGX2020J028); 111 Project (B20030); H2020 Framework program through PNRR iNEST and NEST projects; Ca’ Foscari University of Venice;Full text license: CC BY</p
Long-Range Plasmon-Assisted Chiral Interactions in Nanocrystal Assemblies
No full textMolecular
recognition, which is key to the correct functioning
of most biological processes, is based on chiral entities fitting
into and onto each other. Consequently, the concept of chirality appears
virtually everywhere in biology and biochemistry. One striking optical
manifestation of the chirality of biomolecules is circular dichroism
(CD), which is very typical for biorelated systems. It has been demonstrated
over the past decade that bioassembled plasmonic nanostructures offer
amazing possibilities regarding chirality and optical responses, and
the active research field of chiral bioplasmonics has recently generated
a variety of new sensing platforms. In both molecular and nanoscale
systems, optical manifestations of chirality arise from complex interactions
between nonchiral elements. Such interactions decay rapidly with the
distance between the elements, and therefore, a system with strong
optical chiral responses typically is tightly packed. Here we show
how to transfer chiral interactions efficiently in specially designed
plasmonic geometries over unprecedented distances. In our model, a
long-range chiral interaction occurs between two nanorods (NRs) separated
by a long distance, via transmitter nanoparticles (NPs). We establish
specific conditions for the geometry of the NR–NP–NR
complexes where such long-range chiral interactions should appear.
The proposed chiral effect is expected to be observable under realistic
experimental conditions in nanocrystal bioassemblies, for example,
by employing the so-called DNA origami technology. These and similar
chiral bioassembled plasmonic nanostructures can be used for applications
in the field of optical bioassembled nanomaterials
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