Interplay of Linker Functionalization and Hydrogen Adsorption in the Metal–Organic Framework MIL-101

Functionalization of metal–organic frameworks results in higher hydrogen uptakes owing to stronger hydrogen–host interactions. However, it has not been studied whether a given functional group acts on existing adsorption sites (linker or metal) or introduces new ones. In this work, the effect of two types of functional groups on MIL-101 (Cr) is analyzed. Thermal-desorption spectroscopy reveals that the −Br ligand increases the secondary building unit’s hydrogen affinity, while the −NH2 functional group introduces new hydrogen adsorption sites. In addition, a subsequent introduction of −Br and −NH2 ligands on the linker results in the highest hydrogen-store interaction energy on the cationic nodes. The latter is attributed to a push-and-pull effect of the linkers

A global experiment on motivating social distancing during the COVID-19 pandemic

Finding communication strategies that effectively motivate social distancing continues to be a global public health priority during the COVID-19 pandemic. This cross-country, preregistered experiment (n = 25,718 from 89 countries) tested hypotheses concerning generalizable positive and negative outcomes of social distancing messages that promoted personal agency and reflective choices (i.e., an autonomy-supportive message) or were restrictive and shaming (i.e., a controlling message) compared with no message at all. Results partially supported experimental hypotheses in that the controlling message increased controlled motivation (a poorly internalized form of motivation relying on shame, guilt, and fear of social consequences) relative to no message. On the other hand, the autonomy-supportive message lowered feelings of defiance compared with the controlling message, but the controlling message did not differ from receiving no message at all. Unexpectedly, messages did not influence autonomous motivation (a highly internalized form of motivation relying on one’s core values) or behavioral intentions. Results supported hypothesized associations between people’s existing autonomous and controlled motivations and self-reported behavioral intentions to engage in social distancing. Controlled motivation was associated with more defiance and less long-term behavioral intention to engage in social distancing, whereas autonomous motivation was associated with less defiance and more short- and long-term intentions to social distance. Overall, this work highlights the potential harm of using shaming and pressuring language in public health communication, with implications for the current and future global health challenges

A multi-country test of brief reappraisal interventions on emotions during the COVID-19 pandemic.

The COVID-19 pandemic has increased negative emotions and decreased positive emotions globally. Left unchecked, these emotional changes might have a wide array of adverse impacts. To reduce negative emotions and increase positive emotions, we tested the effectiveness of reappraisal, an emotion-regulation strategy that modifies how one thinks about a situation. Participants from 87 countries and regions (n = 21,644) were randomly assigned to one of two brief reappraisal interventions (reconstrual or repurposing) or one of two control conditions (active or passive). Results revealed that both reappraisal interventions (vesus both control conditions) consistently reduced negative emotions and increased positive emotions across different measures. Reconstrual and repurposing interventions had similar effects. Importantly, planned exploratory analyses indicated that reappraisal interventions did not reduce intentions to practice preventive health behaviours. The findings demonstrate the viability of creating scalable, low-cost interventions for use around the world

A global experiment on motivating social distancing during the COVID-19 pandemic

Finding communication strategies that effectively motivate social distancing continues to be a global public health priority during the COVID-19 pandemic. This cross-country, preregistered experiment (n = 25,718 from 89 countries) tested hypotheses concerning generalizable positive and negative outcomes of social distancing messages that promoted personal agency and reflective choices (i.e., an autonomy-supportive message) or were restrictive and shaming (i.e. a controlling message) compared to no message at all. Results partially supported experimental hypotheses in that the controlling message increased controlled motivation (a poorly-internalized form of motivation relying on shame, guilt, and fear of social consequences) relative to no message. On the other hand, the autonomy-supportive message lowered feelings of defiance compared to the controlling message, but the controlling message did not differ from receiving no message at all. Unexpectedly, messages did not influence autonomous motivation (a highly-internalized form of motivation relying on one’s core values) or behavioral intentions. Results supported hypothesized associations between people’s existing autonomous and controlled motivations and self-reported behavioral intentions to engage in social distancing: Controlled motivation was associated with more defiance and less long-term behavioral intentions to engage in social distancing, whereas autonomous motivation was associated with less defiance and more short- and long-term intentions to social distance. Overall, this work highlights the potential harm of using shaming and pressuring language in public health communication, with implications for the current and future global health challenges

Industrial research of LKMNO spinel cathodes

Celem niniejszej pracy magisterskiej jest zbadanie zależności pomiędzy grubością katody a parametrami wydajnościowymi akumulatora litowo-jonowego. Pierwszym krokiem są badania na poziomie tzw. celi, następnie w ogniwie złożonym z wytworzonego materiału katodowego i komercyjnej anody, a ostatecznie w akumulatorze litowo-jonowym zawierającym dobrane, o najlepszych parametrach grubości wytworzonych w laboratorium zarówno katod jak i anod. W części doświadczalnej jako materiał katodowy został użyty spinel litowo-manganowy podstawiony potasem i niklem (LKMNO). Inne badania sugerują, że zmodyfikowany w ten sposób materiał osiąga dużą pojemność właściwą, rzędu 250 mAh/g, wysoką wydajność oraz stabilność strukturalną, która może utrzymać się na tym samym poziomie przez setki cykli ładowanie/rozładowanie. Oprócz tego, obecność LKMNO w ogniwie umożliwia przeprowadzenie tych procesów bardzo szybko. Jego dodatkową zaletą jest to, iż jest mniej szkodliwy dla środowiska naturalnego w porównaniu do uprzednio wykorzystywanych materiałów katodowych. Do jego produkcji została użyta niskotemperaturowa synteza zol-żel. Umożliwia ona otrzymanie jednorodnych i o wysokiej czystości produktów o rozmiarach nanometrycznych. Materiałem anodowym w pierwszym przypadku była anoda komercyjna, zaś w optymalizowanym ogniwie, które zostało wytworzone w laboratorium - grafit z Na-CMC. Jako elektrolit zastosowano roztwór soli LiPF6 rozpuszczonej w mieszaninie węglanu etylenu i węglanu dietylu (EC/DEC) w stosunku objętościowym 50:50.Techniki, które zostały użyte do badania akumulatorów litowo-jonowych zawierających LKMNO w swoim składzie to: galwanostatyczne testy ładowania/rozładowania oraz elektrochemiczna spektroskopia impedancyjna (EIS). Za pomocą testów możliwe było określenie wydajności oraz odwracalności ogniw. Zaś EIS posłużyła do badania mechanizmów ewolucji i degradacji impedancji.Wyniki wykazały, że najlepiej pracującą katodą okazała się elektroda najgrubsza, czyli 200 µm. Przeciwne rezultaty otrzymano dla anody, bowiem to jedna z najcieńszych, bo 80 µm spełniła postawione wymagania.The aim of this thesis is to investigate the relationship between the cathode thickness and the performance parameters of a lithium-ion battery. The first step is research at the level of the so-called cell, then in a cell consisting of the produced cathode material with a commercial anode and finally in a lithium-ion battery containing selected, with the best parameters thickness, both produced cathodes and anodes in the laboratory.In the experimental part, potassium and nickel substituted lithium-manganese spinel (LKMNO) was used as the cathode material. Other studies suggest that the material modified in this way, achieves a high specific capacity, 250 mAh/g, high efficiency and structural stability that can be maintained at the same level for hundreds of charge/discharge cycles. In addition, the presence of LKMNO in the cell enables that these processes are carried out very quickly. Its additional advantage is that it is less harmful to the environment compared to previously used cathode materials. Low-temperature sol-gel synthesis was used to produce this material. It makes that it is possible to obtain homogeneous and high-purity products with nanometric dimensions. The anode material in the first part was a commercial anode, in the optimized cell, which was produced in the laboratory - graphite with Na-CMC. The electrolyte was a solution of LiPF6 salt dissolved in a 50:50 volumetric mixture of ethylene carbonate and diethyl carbonate (EC/DEC).The techniques that were used to test lithium-ion batteries containing LKMNO in their composition are: galvanostatic charge/discharge tests and electrochemical impedance spectroscopy (EIS). Using the tests, it was possible to determine the efficiency and reversibility of the cells. The EIS was used to study the mechanisms of evolution and degradation of impedance.The results showed that the thickest electrode, 200 µm, turned out to be the best working cathode. The opposite results were obtained for the anode, because one of the thinnest, 80 µm, met requirements

Simultaneous potentiometric determination of potassium, sodium, calcium and chloride ions by flow technique using gold electrodes with a polymer layer.

Celem niniejszej pracy było oznaczenie jonów Na+, K+, Ca2+ i Cl- stosując jonoselektywne elektrody membranowe typu all-solid-state z warstwą przewodzącą, którą pełnił polimer PEDOT, z wykorzystaniem techniki wstrzykowo-przepływowej FIA z detekcją potencjometryczną. Wykorzystano tutaj wstrzykową analizę przepływową i nowatorskie elektrody jonoselektywne. Najważniejszym składnikiem aktywnym tych elektrod jest membrana o właściwościach jonowymiennych. Ich zaletą na pewno jest to, że pomiar jest bezpośredni, szybki i prosty. Wprowadzenie przewodzącego polimeru powoduje zwiększenie czułości na wykrywane jony. Występuje on w postaci warstwy nałożonej w sposób elektrochemiczny.The aim of this study was to determine Na +, K +, Ca2 + and Cl- ions using ion selective all-solid-state membrane electrodes with a conductive layer, which was performed by the PEDOT polymer, using the ​​flow injection analysis with potentiometric detection. Flow injection analysis and novel ion selective electrodes were used here. The most important active ingredient of these electrodes is a membrane with ion-exchange properties. Their advantage is that the measurement is direct, quick and simple. The introduction of a conductive polymer increases the sensitivity to the detected ions. It exists as an electrochemical layer

Microscopic Study of TiF3 as Hydrogen Storage Catalyst for MgH2

To understand the catalytic influence of TiF3 on the de- and rehydrogenation of ball milled MgH2–TiF3, a detailed study has been performed of the different crystallographic phases of the de- and rehydrogenated materials. Rietveld-refined XRD analysis of the dehydrogenated material indicates the presence of a rutile, nonstoichiometric MgF2–x phase and a hexagonal Mg1–yTiyFz phase. After rehydrogenation three different fluorine environments were found by 19F NMR, which can be attributed to MgF2–x, MgF2–xHx, and MgF2–x dispersed with MgO nanodomains. The remarkable MgF2–xHx phase, which is apparently formed from the nonstoichiometric MgF2–x phase in the dehydrogenated material, may indicate a diffusion pathway of hydrogen within Mg/MgH2–x. Furthermore, the previously found nonstoichiometric MgH2–x phase appears to be metastable as is observed by XRD analysis after long-term storage. TEM with EDX measurements performed for both dehydrogenated and rehydrogenated samples provide information that the nanoparticles are highly crystalline and that the catalyst is homogenously distributed over the sample at a 100 nm length scale. More locally, the fluorine-containing phase is observed mainly at the surface of the Mg and MgH2 particles and the Ti-containing species are present throughout the particles, likely as TiH2 inclusions in the Mg structure and/or as Mg–Ti–F compound. Additionally, an about 2–5.5 nm MgO layer covers the Mg aggregates. A model of the hydrogen uptake and sample morphology is proposed.status: publishe

Irreversible High-Temperature Hydrogen Interaction with the Metal Organic Framework Cu-3(BTC)(2)

Unsaturated metal coordination sites in metal organic frameworks (MOFs) offer preferential hydrogen adsorption sites. In addition, MOFs can be applied as scaffolds for nano metal hydrides operating at elevated temperatures. For these reasons, the thermal stability of the framework with unsaturated Cu2+ coordination sites in a hydrogen atmosphere has been investigated in Cu3(BTC)2. It is found that Cu3(BTC)2 irreversibly binds 1.1 wt % of hydrogen at the temperatures between 323 and 423 K and 2 bar H2 pressure, which corresponds to three hydrogen atoms per BTC ligand. In accordance, FT-IR and NMR spectroscopy show that the BTC linkers are converted to their acid form, whereas XRD reveals the presence of reduced Cu0 metal particles and decomposition of the framework. When designing more strongly interacting MOFs for H2 storage applications or as template for light metal hydrides, one has to take possible reduction of the metal centers and the stability of the lattice into account.status: publishe

The Effect of Er:YAG Laser on a Shear Bond Strength Value of Orthodontic Brackets to Enamel—A Preliminary Study

We sought to evaluate the effects of Er:YAG laser (LightTouch, LightInstruments, Israel) conditioning on enamel roughness and shear bond strength of orthodontic brackets on enamel. Eighteen human molars (n = 9) and premolars (n = 9), were divided into 3 groups depending on the enamel conditioning method; Er:YAG laser (G1, n = 6), conventional etching with 37% orthophosphoric acid (G2, n = 6), Er:YAG laser combined with conventional etching (G3, n = 6). Er:YAG laser parameters were as follows: energy: 100 mJ, frequency: 10 Hz, exposure time: 10 s, applicator diameter: 600 μm, fluence: 35.37 J/cm2, distance: 1 mm away from a tooth, cooling: 80%. An MTS 858 MiniBionix® machine was used to determine the shear bond strength (MTS System, Eden Prairie, MN, USA). The enamel structure was assessed using X-ray microtomography (SkyScan 1172, Bruker, Kontich, Belgium). The highest values of shear bond strength were obtained in the G3 group (9.23 ± 2.38 MPa) and the lowest values in the G2 group (6.44 ± 2.11 MPa) (p < 0.05). A significant change in the enamel surface was noted after applying laser, reaching up to 9% of enamel thickness, which was not observed in the etched samples. Moreover, the Er:YAG laser-irradiated enamel surface was characterized by the greatest roughness. The combined use of an Er:YAG laser with a conventional etching improves the adhesion of composite materials to the tooth