Silicon nanoparticles with a polymer-derived carbon shell for improved lithium-ion batteries: Investigation into volume expansion, gas evolution, and particle fracture

Silicon (Si) and composites thereof, preferably with carbon (C), show favorable lithium (Li) storage properties at low potential, and thus hold promise for application as anode active materials in the energy storage area. However, the high theoretical specific capacity of Si afforded by the alloying reaction with Li involves many challenges. In this article, we report the preparation of small-size Si particles with a turbostratic carbon shell from a polymer precoated powder material. Galvanostatic charge/discharge experiments conducted on electrodes with practical loadings resulted in much improved capacity retention and kinetics for the Si/C composite particles compared to physical mixtures of pristine Si particles and carbon black, emphasizing the positive effect that the core−shell-type morphology has on the cycling performance. Using in situ differential electrochemical mass spectrometry, pressure, and acoustic emission measurements, we gain insights into the gassing behavior, the bulk volume expansion, and the mechanical degradation of the Si/C composite-containing electrodes. Taken together, our research data demonstrate that some of the problems of high-content Si anodes can be mitigated by carbon coating. Nonetheless, continuous electrolyte decomposition, particle fracture, and electrode restructuring due to the large volume changes during battery operation (here, ∼170% in the voltage range of 600−30 mV vs Li+/Li) remain as serious hurdles toward practical implementation

Landslide on railway line no 8 Warszawa - Kraków in Sadowie - new possibilities of monitoring

W artykule przedstawiono problem osuwiska w miejscowości Sadowie na ważnej linii kolejowej nr 8 Kraków - Warszawa. Osuwisko to wykazywało aktywność już od 1934 roku, a w 2010 roku po ulewnych deszczach i powodzi w Polsce uaktywniło się i zagroziło linii kolejowej. Omówiono mechanizm powstawania osuwiska i budowę geologiczną obszaru, na którym znajduję się osuwisko. Zaproponowano uzupełnienie monitoringu osuwiska metodą skanowania laserowego nowoczesnym przyrządem RIEGL-VZ 400 i pokazano wykonany pomiar bazowy.The problem of landslide in a town of Sadowie along important railway line No. 8 Warszawa - Kraków has been presented in the paper. The landslide has been active since 1934, but in 2000, after torrential rain and flood, it activated and the railway line was threatened with it. The geological structure of the area, where the landslide is located has been presented. The mechanism of landslide creation has been described. The idea to complement the landslide monitoring with laser scanning using modern RIEGL-VZ 400 tool has been formulated and the result of basic measurement has been shown

Landslide protection effectiveness monitoring on the example of Sadowie landslide located on railway line no. 8 Warszawa - Krakow

W artykule przedstawiono problem występowania osuwisk wzdłuż linii kolejowych. Omówiono metody monitorowania ruchów mas ziemnych, a także sposoby zabezpieczania nasypów i skarp przed zjawiskami osuwiskowymi. Na przykładzie osuwiska w miejscowości Sadowie wzdłuż ważnej linii kolejowej nr 8 Kraków – Warszawa przedstawiono próbę monitoringu aktywności osuwiska metodą skanowania laserowego przyrządem RIEGL-VZ 400 oraz zaprezentowano wyniki takich pomiarów.This paper presents the problem of the landslides occurrence along the railway lines. The methods of earth movement monitoring, as well as ways to protect embankments and slopes against landslides have been discussed. Ba-sed on the example of Sadowie landslide along the important railway line no. 8 Krakow – Warszawa the authors present the method for monitoring landslide activity using laser scanning device RIEGL VZ-400 together with the results of such measurements

Is the advancement of diabetic angiopathy evaluated as ankle-brachial index directly associated with current glycaemic control?

Introduction and objective: Diabetic patients are at high risk for peripheral arterial disease (PAD) characterized by symptoms of intermittent claudication or critical limb ischemia. Measurement of ankle-brachial index (ABI) has emerged as the diagnostic tool of choice, because it is relatively simple, non-invasive and inexpensive. It is also an independent marker of increased morbidity and mortality from cardiovascular diseases. The aim of the presented study was to assess the relationship between current glycemic control defined by glycated hemoglobin (HbA1c) level, and quantitative changes in the arteries of the lower limbs in patients with type 2 diabetes. Materials and methods: 175 patients with type 2 diabetes hospitalized in the Diabetology Ward were studied. VENO Doppler and a sphygmomanometer were used to assess blood flow. Results: The average level of HbA1c was assessed at 8.48%. Although the average level of ABI indicator was 1.20 (normal), only 45% of evaluated patients had their individual index within the normal range. Signs of ischemia were found in 17.7% of examined subjects. There was no conclusive correlation between ABI and HbA1c levels. Conclusions: The current level of glycemic control evaluated as HbA1c has no direct impact on the advancement of diabetic angiopathy evaluated as ABI

From Molecular Structure to Macromolecular Organization: Keys to Design Supramolecular Biomaterials

In the past decade, significant progress has been made in the field of biomaterials, for potential applications in tissue engineering or drug delivery. We have recently developed a new class of thermoplastic elastomers, based on ureidopyrimidinone (UPy) quadruple hydrogen bonding motifs. These supramolecular polymers form nanofiber-like aggregates initially <i>via</i> the dimerization of the UPy units followed by lateral urea-hydrogen bonding. Combined kinetic and thermodynamic studies unravel the pathway complexity in the formation of these polymorphic nanofibers and the subtlety of the polymer’s design, while these morphologies are so critically important when these materials are used in combination with cells. We also show that the cell behavior directly depends on the length and shape of the nanofibers, illustrating the key importance of macromolecular and supramolecular organization of biomaterials. This study leads to new design rules that determine what factors are decisive for a polymer to be a good candidate as biomaterial

Hydrogel formation by the 'topological conversion' of cyclic PLA-PEO block copolymers

An amphiphilic cyclic block copolymer consisting of poly(L- or D-lactide) and poly(ethylene oxide), that is, PLLA-PEO or PDLA-PEO, was synthesized from its corresponding linear triblock precursor, PLLA-PEO-PLLA or PDLA-PEO-PDLA, respectively, with alkenyl end groups. A mixture of the micellar dispersions of linear PLLA-PEO-PLLA and linear PDLA-PEO-PDLA formed a gel upon heating, whereas a mixture of the cyclic counterparts did not undergo this phase transition. These results suggest that the gelation behavior is directed by the topology of the polymer components. Furthermore, cyclic PLLA-PEO and cyclic PDLA-PEO block copolymers incorporating photocleavable o-nitrobenzyl units were synthesized. A mixture of the micellar dispersions of these block copolymers formed a gel upon ultraviolet irradiation via the 'topological conversion'