Structural study and phase transition investigation in a simple synthesis of porous architected-ZnO nanopowder

In this work, zinc oxide powder with a rectangular-shaped porous architecture, made of numerous spherical nanometric particles,was obtained. Asimple precipitation/decomposition procedure was used comprising a zinc oxalate intermediate, obtained from zinc sulfate and oxalic acid without any additives. Detailed studies on zinc oxalate dehydration, decomposition and zinc oxide formation, were carried out using in-situ temperature X-ray diffraction and thermogravimetric analysis. During the investigation, the temperature dependence of particle sizes, lattice parameters and crystal structures of ZnC2O4·2H2O, ZnC2O4 and ZnO nanopowders were analyzed from room temperature to 450 °C. Structural transitions were also discussed. The structure and morphology of the as-prepared ZnO nanopowder were investigated by electron microscopy and compared to the crystalline rectangular shape of ZnC2O4·2H2O. The calcination temperature, counter ion and precipitate agent were found to be related to the product's shape and diameter. Spherical ZnO nanoparticleswith diameters of less than 20 nm and a maximum specific surface of 53 m2/g were obtained using thismethod

Synthesis of ruthenium-phosphorus dyes and their incorporation in ZnO transparent conducting oxide and ZnO semi-conductor thin films for photovoltaic application

Cette thèse est consacrée au développement de nouveaux colorants moléculaires a base de complexes de ruthénium phosphorés, d'oxydes conducteurs transparents (TCO) et de matériaux semi-conduteurs (SC) à base de ZnO en vue de leur application dans des cellules solaires à colorants. Des voies synthétiques originales ont été développées pour la préparation de complexes symétriques et non symétriques de type ligands phosphorés fonctionnalisés. Les résultats obtenus souligne le rôle prépondérant des ligands phosphorés dans le contrôle des propriétés électroniques et optiques de ces colorants. Nous avons aussi étudié ZnO sous forme de films minces. En ciblant une interface TCO/SC homogène, des TCO à base d'oxyde de zinc dopés au Ga (ZnO:Ga) et des SC à base d'oxyde de zinc pur ont été déposés par pulvérisation cathodique radiofréquence à partir de cibles céramiques. Les microstructures et les propriétés physiques de ces matériaux ont été étudiées. Les conditions de dépôts ont été optimisées pour préparer des films minces TCO de ZnO:Ga présentant une grande transparence optique et de bonnes conductivités électroniques et des films minces SC à grande surface. La surface accessible des films minces ZnO a ensuite été améliorée par attaque chimique humide. Dans la dernière partie, nous avons associé les colorants moléculaires aux matériaux SC et TCO par greffage chimique. Des nanopoudres de ZnO ont été élaborées pour effectuer des tests de greffage avant leurs validations sur les matériaux en couche mince. Le colorant est ancré sur ZnO par les fonctions phosphorées. L'intégration de ces matériaux dans des cellules photovoltaïques à colorant sera l'objet de développements futurs.In this work, we studied the development of new molecular ruthenium-phosphorus dyes and new Transparent Conducting Oxide (TCO) and ZnO Semi-Conductor (SC) materials in view of integrating them in dye sensitized solar cells. This thesis described first the original synthetic pathways that were developed to prepare both symmetrical and non-symmetrical complexes [Ru(bpy)2LL']n+ (L, L' : functionalized phosphorus ligands). Results highlight the predominant role of the phosphorus ligands in tuning the electronic and optical properties of the corresponding dyes. Secondly, we studied the preparation of new ZnO materials. In the goal of obtaining a homogeneous TCO/SC interface, zinc oxide doped Ga (ZnO:Ga) TCO and zinc oxide SC thin films were deposited by RF magnetron sputtering using ceramic targets. The microstructure and physical properties of these materials were studied. The deposition conditions were specifically optimized to prepare dense ZnO:Ga thin films with high transparency and good electrical conductivity for the TCO layer on one hand, and porous ZnO with high accessible surface for the SC layer on the other hand. The accessible surface of relatively porous ZnO thin films were further extended by post-deposition wet chemical etching.Finally, we associated the molecular dyes to the SC and the TCO materials by chemical grafting. Preliminary grafting tests were first investigated on homemade ZnO nanopowders before being validated on thin film materials. In these new materials, the dye is anchored to the ZnO through phosphorus functionalized functions. As a continuation of this work, the integration of these new materials in DSSCs will be the focus of further studies

Detailed microstructure analysis of as-deposited and etched porous ZnO films

ZnO nanostructured materials in thin film forms are of particular interest for photovoltaic or photo-catalysis processes but they suffer from a lack of simple methods for optimizing their microstructure.We have demonstrated that microporous ZnO thin films with optimized inter grain accessibility canbe produce by radio frequency magnetron sputtering process and chemical etching with 2.75 mM HClsolution for different duration. The as-deposited ZnO thin films were first characterized in terms ofstructure, grain size, inter grain space, open cavity depth and total thickness of the film by XRD, AFM,SEM, profilometry and optical measurements. A specific attention was dedicated to the determinationof the surface enhancement factor (SEF) by using basic geometrical considerations and images treat-ments. In addition, the porous fraction and its distribution in the thickness have been estimated thanksto the optical simulation of the experimental UV–Visible–IR spectrums using the Bruggeman dielectricmodel and cross section SEM images analysis respectively. This study showed that the microstructureof the as-deposited films consists of a dense layer covered by a porous upper layer developing a SEF of12–13 m2m−2. This two layers architecture is not modified by the etching process. The etching processonly affects the upper porous layer in which the overall porosity and the inter-grain space increase withthe etching duration. Column diameter and total film thickness decrease at the same time when the filmsare soaked in the HCl bath. The microporous structure obtained after the etching process could gener-ate a great interest for the interfaces electronic exchanges for solar cells, photocatalysis and gas sensorsapplications

Correlation Between Gait and Near-Infrared Brain Functional Connectivity Under Cognitive Tasks in Elderly Subjects With Mild Cognitive Impairment

Older adults with mild cognitive impairment (MCI) have a high risk of developing Alzheimer’s disease. Gait performance is a potential clinical marker for the progression of MCI into dementia. However, the relationship between gait and brain functional connectivity (FC) in older adults with MCI remains unclear. Forty-five subjects [MCI group, n = 23; healthy control (HC) group, n = 22] were recruited. Each subject performed a walking task (Task 01), counting backward–walking task (Task 02), naming animals–walking task (Task 03), and calculating–walking task (Task 04). The gait parameters and cerebral oxygenation signals from the left prefrontal cortex (LPFC), right prefrontal cortex (RPFC), left motor cortex (LMC), right motor cortex (RMC), left occipital leaf cortex (LOL), and right occipital leaf cortex (ROL) were obtained simultaneously. Wavelet phase coherence was calculated in two frequency intervals: low frequency (interval I, 0.052–0.145 Hz) and very low frequency (interval II, 0.021–0.052 Hz). Results showed that the FC of RPFC–RMC is significantly lower in interval I in Task 03 compared with that in Task 02 in the MCI group (p = 0.001). Also, the right relative symmetry index (IDpsR) is significantly lower in Task 03 compared with that in Task 02 (p = 0.000). The IDpsR is positively correlated with the FC of RPFC–RMC in interval I in the MCI group (R = 0.205, p = 0.041). The gait symmetry such as left relative symmetry index (IDpsL) and IDpsR is significantly lower in the dual-task (DT) situation compared with the single task in the two groups (p < 0.05). The results suggested that the IDpsR might reflect abnormal change in FC of RPFC–RMC in interval I in the MCI population during Task 03. The gait symmetry is affected by DTs in both groups. The findings of this study may have a pivotal role in the early monitoring and intervention of brain dysfunction among older adults with MCI

Electrostatic spraying of membrane electrode for proton exchange membrane fuel cell

Abstract(#br)In order to improve the performance of proton exchange membrane fuel cell (PEMFC), the optimization of electrostatic spraying of membrane electrode was conducted. The influence of the spraying voltage on morphology, elemental composition of catalyst layer, and performance of the PEMFC were investigated. The results show that increasing spraying voltage could reduce agglomeration of the carbon-supported platinum particles, leading to more uniform pore distribution. High voltage did not accelerate oxidation of platinum catalyst. A high electrochemical active surface area of 26.18 m 2 /g pt was obtained when the platinum-carbon catalyst layer was deposited in cone jet mode. With further increasing spraying voltage, the total ohmic resistance and catalytic activity were changed slightly, whereas the charge transfer resistance was increased. Using the optimized electrostatic spraying parameters (injection rate = 100 μL min −1 , spraying voltage = 8.5 kV, and working distance = 12 mm), a peak power density of 1.408 W cm −2 was obtained with an output voltage of 0.451 V

Different Effects of Total Bilirubin on 90-Day Mortality in Hospitalized Patients With Cirrhosis and Advanced Fibrosis: A Quantitative Analysis

Introduction: Total bilirubin (TB) is a major prognosis predictor representing liver failure in patients with acute on chronic liver failure (ACLF). However, the cutoff value of TB for liver failure and whether the same cutoff could be applied in both cirrhotic and non-cirrhotic patients remain controversial. There is a need to obtain the quantitative correlation between TB and short-term mortality via evidence-based methods, which is critical in establishing solid ACLF diagnostic criteria.Methods: Patients hospitalized with cirrhosis or advanced fibrosis (FIB-4 > 1.45) were studied. TB and other variables were measured at baseline. The primary outcome was 90-day transplantation-free mortality. Multi-variable Cox proportional hazard model was used to present the independent risk of mortality due to TB. Generalized additive model and second derivate (acceleration) were used to plot the “TB-mortality correlation curves.” The mathematical (maximum acceleration) and clinical (adjusted 28-day transplantation-free mortality rate reaching 15%) TB cutoffs for liver failure were both calculated.Results: Among the 3,532 included patients, the number of patients with cirrhosis and advanced fibrosis were 2,592 and 940, respectively, of which cumulative 90-day mortality were 16.6% (430/2592) and 7.4% (70/940), respectively. Any increase of TB was found the independent risk factor of mortality in cirrhotic patients, while only TB >12 mg/dL independently increased the risk of mortality in patients with advanced fibrosis. In cirrhotic patients, the mathematical TB cutoff for liver failure is 14.2 mg/dL, with 23.3% (605/2592) patients exceeding it, corresponding to 13.3 and 25.0% adjusted 28- and 90-day mortality rate, respectively. The clinical TB cutoff for is 18.1 mg/dL, with 18.2% (471/2592) patients exceeding it. In patients with advanced fibrosis, the mathematical TB cutoff is 12.1 mg/dL, 33.1% (311/940) patients exceeding it, corresponding to 2.9 and 8.0% adjusted 28- and 90-day mortality rate, respectively; the clinical TB cutoff was 36.0 mg/dL, 1.3% (12/940) patients above it.Conclusion: This study clearly demonstrated the significantly different impact of TB on 90-day mortality in patients with cirrhosis and advanced fibrosis, proving that liver failure can be determined by TB alone in cirrhosis but not in advanced fibrosis. The proposed TB cutoffs for liver failure provides solid support for the establishment of ACLF diagnostic criteria

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field

One Belt One Road Project and Turkey

Tarihi İpek Yolu, toplumların gelişimine ve iletişimine büyük katkılarda bulunmuştur. Geçmiş yıllarda İpek Yolu'nu canlandırmak için birçok proje tasarlanmasına rağmen "Modern İpek Yolu" rüya gibi düşünülüyordu. 2013 yılında Çin başkanı Xi Jinping, Avrupa ve Asya'yı birbirine bağlaması beklenen "One Belt One Road" adlı bir girişim öne sürmüştür. Bu girişim tüm katılımcı ülkeler için ekonomi, politika ve kültür değişimi açısından çeşitli avantajlar içermektedir. Çin'de başlayan bu girişim, kısa süre içinde büyük bir ilgi görmüştür. Türkiye de dahil olmak üzere bir çok ülke bu projeye olumlu ve destekleyici gözle bakmaktadır. Türkiye, İpek Yolu'nun doğal aynı zamanda önemli bir parçası olarak görülmektedir. Bu çalışmanın temel amacı "Bir Kuşak Bir Yol" projesinin ilerleyişini araştırmak ve bu bağlamda Çin-Türkiye ilişkisini daha çok ekonomi işbirlikleri açısından analiz etmektir. Sonuç olarak, "Bir Kuşak Bir Yol" projesiyle ilgili olarak Çin ve Türkiye arasındaki işbirliğinde bazı risklerin olması ihtimaline rağmen ortak kazançların oluşağı bu hedefe, iki ülke arasındaki siyasi koordinasyon ve iyi bir anlaşma yoluyla ulaşılabilecektir. Çünkü bu iki ülke arasında köklü çıkar çatışmaları yoktur.The ancient Silk Road has made great contribution to the development and communication of human society in history. During the past years many projects have been designed to revitalize the Silk Road but still a "Modern Silk Road" looked like a dream. In 2013 the president of China Xi Jinping, put forward an initiative called "One Belt One Road" which is expected to connected Europe and Asia. It contains various benefits for all participant countries in terms of economy, politics and culture exchange. Within a short time this initiative brought up by China has gained high focus of the world. Most of the responses are positive and supportive, including Turkey. Turkey is regarded as a natural part in the historical Silk Road and also a key partener in the modern Silk Road project. The main purpose of this study is to research the progress of "One Belt One Road" project and in this context to analyze the Sino-Turkey relationship mostly in the aspect of economy cooperations. As the conclusion although there are some hidden risks in the cooperation between China and Turkey in regards of "One Belt One Road" project, the win-win objective could be achieved through policy coordination and better understanding between two people, as no root conflicts of interest exist between the two countries

Bis(2,2′-bipyridine)[1,9-bis(diphenylphosphanyl)-1,2,3,4,6,7,8,9-octahydropyrimido[1,2-a]pyrimidin-5-ium]ruthenium(II) hexafluoridophosphate dibromide dichloromethane disolvate monohydrate

In the cation of the title complex, [Ru(C31H32N3P2)(C10H8N2)2](PF6)(Br)2·2CH2Cl2·H2O, the ruthenium ion is coordinated in a distorted octahedral geometry by two 2,2′-bipyridine (bpy) ligands and a chelating cationic N-diphenylphosphino-1,3,4,6,7,8-hexahydro-2-pyrimido[1,2-a]pyrimidine [(PPh2)2-hpp] ligand. The tricationic charge of the complex is balanced by two bromide and one hexafluoridophosphate counter-anions. The compound crystallized with two molecules of dichloromethane (one of which is equally disordered about a Cl atom) and a water molecule. In the crystal, one of the Br anions bridges two water molecules via O—H...Br hydrogen bonds, forming a centrosymmetric diamond-shaped R42(8) motif. The cation and anions and the solvent molecules are linked via C—H...F, C—H...Br, C—H...Cl and C—H...O hydrogen bonds, forming a three-dimensional network