Search

Temporal variability of the soil hydraulic properties is still an open issue. The present study deals with results of ponded infiltration experiments performed annually in a grid of permanent measurement points (18 spatial and 14 temporal replicates). Single ring infiltrometers were installed in 2003 at a meadow site in the Bohemian Forest highlands, the Czech Republic. The soil at the plot is coarse sandy loam classified as oligotrophic Eutric Cambisol. Soil water flow below infiltration rings has distinctly preferential character.

Differently substituted pyrrole-azo-benzene molecular photoswitches were prepared in a straightforward synthetic way. Their fundamental properties were investigated by XRD analysis, differential scanning calorimetry, thermogravimetric analysis, cyclic voltammetry, UV-Vis absorption spectroscopy, Hyper-Rayleigh Scattering, and NMR spectroscopy; the experimental results were further corroborated by DFT calculations. Thermal robustness, the HOMO/LUMO levels, and the absorption properties were altered mostly by substituting the N-methylpyrrole moiety and further fine-tuned by modifying the benzene substituents. The pyrrole substituent also proved crucial for the second-order non-linear optical (NLO) response as well as the photoswitching performance. Both fast and slow molecular switches can be designed with the half-life of the (Z) -isomer ranging from 48 seconds to 23.28 hours and the E/Z molar ratio up to 12/88. This comprehensive study allowed elucidation of the fundamental structure-property relationships and subsequently addresses the key aspects of the property tuning via substitution in molecular azo-photoswitches., (© 2024 Wiley-VCH GmbH.)

End-of-life tires are utilized for various purposes, including sports pitches and playground surfaces. However, several substances used at the manufacture of tires can be a source of concerns related to human health or environment's adverse effects. In this context, it is necessary to map whether this approach has the desired effect in a broader relation. While the negative effects on human health were investigated thoroughly and legislation is currently being revisited, the impact on aquatic or soil organisms has not been sufficiently studied. The present study deals with the exposure of freshwater and soil organisms to rubber crumb using the analysis of heavy metal and polycyclic aromatic hydrocarbon concentrations. The obtained results refer to substantial concerns related to freshwater contamination specifically, since the increased concentrations of zinc (7 mg·L -1 ) and polycyclic aromatic hydrocarbons (58 mg·kg -1 ) inhibit the growth of freshwater organisms, Desmodesmus subspicatus , and Lemna minor in particular. The performed test with soil organisms points to substantial concerns associated with the mortality of earthworms as well. The acquired knowledge can be perceived as a roadmap to a consistent approach in the implementation of the circular economy, which brings with it a number of so far insufficiently described problems.

The currently limited portfolio of volatile organoselenium compounds used for atomic layer deposition (ALD) has been extended by designing and preparing a series of four-, five- and six-membered cyclic silylselenides. Their fundamental properties were tailored by alternating the ring size, the number of embedded Se atoms and the used peripheral alkyl chains. In contrast to former preparations based on formation of sodium or lithium selenides, the newly developed synthetic method utilizes a direct and easy reaction of elemental selenium with chlorosilanes. Novel 2,2,4,4-tetraisopropyl-1,3,2,4-diselenadisiletane, which features good trade-off between chemical/thermal stability and reactivity, has been successfully used for gas-to-solid phase reaction with MoCl 5 affording MoSe 2 . A thorough characterization of the as-deposited 2D MoSe 2 flakes revealed its out-of-plane orientation and high purity. Hence, the developed four-membered cyclic silylselenide turned out to be well-suited Se-precursor for ALD of MoSe 2 ., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The current portfolio of organoselenium compounds applicable as volatile precursors for atomic layer deposition can be denoted as very limited. Hence, we report herein facile and cost-effective preparation of two bis(trialkylstannyl)selenides as well as one selenole and three bis(trialkylsilyl)selenides. Their syntheses have been optimized to: (i) use readily available and inexpensive starting materials, (ii) involve operationally simple methodology (heating in a pressure vessel), (iii) use a minimum amount of additives and catalysts, and (iv) either exclude additional purification or involve only simple distillation. The chemical structure of prepared Se derivatives was confirmed by multinuclear NMR and GC/MS. Their fundamental thermal properties were investigated by differential scanning calorimetry (DSC) and TGA methods that revealed thermal stability within the range of 160-300 °C.

Three cyclic silylselenides were prepared in a straightforward manner. Property tuning has been achieved by varying the ring size and the number of embedded selenium atoms. All silylselenides possess improved resistance towards moisture and oxidation as well as high thermal robustness and sufficient volatility with almost zero residues. The six-membered diselenide proved to be particularly superior Se precursors for atomic layer deposition and allowed facile preparation of MoSe 2 layers. Their structure and composition have been investigated by Raman and X-ray photoelectron spectroscopy as well as scanning electron microscopy revealing vertically aligned flaky shaped nanosheets., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Fourteen new D-π-A push-pull chromophores based on two isomeric thienothiophene donors and seven acceptors of various electronic natures have been designed and conveniently synthesized. In contrast to known thienothiophene push-pull molecules, the prepared small chromophores proved to be organic materials with easily tunable thermal, electrochemical and (non)linear optical properties. It has also been shown that small structural variation may result in significantly improved/varied fundamental properties. Very detailed structure-property relationships were elucidated within the systematically developed series of push-pull molecules, which may serve as a useful guide in designing new D-π-A molecules based on fused thiophene scaffolds.

Cholangiocarcinoma (CC) is a rare malignant tumour arising from cholangiocytes, and its prognosis is usually unfavourable, mostly as a result of late diagnosis of the tumour. The current incidence of cholangiocarcinoma in the Czech Republic is 1.4/100,000 inhabitants per year; in less than 30 % of patients with CC, one of the known risk factors can be identified, most frequently, primary sclerosing cholangitis. Only patients with early diagnosed and surgically amenable cholangiocarcinoma are likely to have a longer survival time; in their case, survival for more than five years has been achieved in 20 % to 40 %. From the perspective of the need for early diagnosis of CC, a significant part is played by imaging and histopathologic evaluation; the early diagnostic significance of oncomarkers is limited. The rational early diagnosis of CC consists in effective use of differentiated advantages of different imaging modalities - MRI with DSA appears to be the optimal method, endosonography is a sensitive method for the identification of malignancy in the hepatic hilum or distal common bile duct, MRCP (magnetic resonance cholangiopancreatography) is used to display pathological changes in the biliary tree, ERCP (endoscopic retrograde cholangiopancreatography) allows material removal for histopathological examination. Other new approaches are also beneficial, such as IDUS - intraductal ultrasonography of biliary tract or SPY-GLASS, enabling examination of the bile ducts by direct view with the possibility of taking targeted biopsies. Sensitivity and specificity of histology and cytology can be increased by using the molecular cytogenetic FISH method, i.e. fluorescence in situ by hybridization, with a specificity of 97 %.

Objective: To evaluate the results of single embryo transfers, on a set of patients, for a given period of time., Design: Retrospective study., Setting: Pronatal Sanatorium, Prague., Methods: Between January 2008 and May 2010, we evaluated the results of all cycles with single embryo transfers in our workplace. There were four groups of patients: the first group with elective single embryo transfers (ESET, n=147), the second group with only a single embryo transfer without selection (SET n=269), the third group with transfer of one embryo derived from the native cycle (NC, n=70) and the last group with transfer of only one embryo examinated by preimplantation genetic diagnosis (PGD, n=104). All patients were monitored by age, length of cultivation of embryos, clinical pregnancy rate/transfer (CPR/ET), pregnancy loss (AB) and baby take home rate (BTR). Statistical evaluation was performed using the chi square test., Results: The group with ESET achieved a significantly higher success rate (50% CPR/ET, p<0.001) compared to the other groups: 22% for SET, 7% of spontaneous cycles and 18% after PGD. A significant difference (p<0.001) was also apparent in the evaluation of BTR: ESET 41%, 16% SET, NC 4%, 12.5% of PGD. Patients that made ESET were significantly younger (p<0.001) compared to the other monitored groups (32.9 ESET, SET 35.2, NC 39.6, 39.1 PGD)., Conclusion: We consider that assisted reproduction is only successful with the birth of one healthy child. For women 38 years old or younger the most successful treatment is to transfer a single high quality embryo and to therefore eliminate multiple pregnancy. The age of a woman and the quality of the embryo are major prognostic factors.