Magic-sized semiconductor nanocrystals (MSNCs) grow via discrete jumps between specific sizes. Despite their potential to offer atomically precise structures, their use has been limited by poor ...stability and trap-dominated photoluminescence. Recently, CdSe MSNCs have been grown to larger sizes. We exploit such particles and demonstrate a method to grow shells on CdSe MSNC cores via high-temperature synthesis. Thin CdS shells lead to dramatic improvements in the emissive properties of the MSNCs, narrowing their fluorescence line widths, enhancing photoluminescence quantum yields, and eliminating trap emission. Although thicker CdS shells lead to decreased performance, Cd x Zn1–x S alloyed shells maintain efficient and narrow emission lines. These alloyed core/shell crystallites exhibit a tetrahedral shape, in agreement with a recent model for MSNC growth. Our results indicate that MSNCs can compete with other state-of-the-art semiconductor nanocrystals. Furthermore, these core/shell structures will allow further study of MSNCs and their potential for atomically precise growth.
The cell adhesion molecule N-cadherin is involved in several processes during central nervous system development, but also in certain pathologic conditions in the adult brain, including tumorigenesis ...and Alzheimer's disease. N-cadherin function in inflammatory demyelinating disease has so far not been investigated. In vitro studies suggest a role of N-cadherin in myelination; on the other hand N-cadherin has been implicated in the formation of the glial scar, which is believed to impede remyelination. The aim of our study was to investigate the expression pattern of N-cadherin immunoreactivity in experimental autoimmune encephalomyelitis induced by myelin oligodendrocyte glycoprotein (MOG-EAE), an animal model closely mimicking multiple sclerosis. It allows a detailed evaluation of all stages of de‐ and remyelination during lesion development. Immunopathological evaluation was performed on paraffin-embedded CNS sections sampled at days 20 to 120 post immunization. We found a predominant expression of N-cadherin on oligodendrocytes in early remyelinating lesions, while in fully remyelinated shadow plaques there was no detectable immunoreactivity for N-cadherin. This expression pattern indicates a role of N-cadherin in the initiation of remyelination, most likely by providing a guidance between myelin lamellae and oligodendrocytes. Once the initial contact is made N-cadherin is then rapidly downregulated and virtually absent after completion of the repair process, analog to its known role in developmental myelination. Our results show that N-cadherin plays an important role in creating a remyelination-facilitating environment.
► N-cadherin is an adhesion molecule with vital roles during development. ► It is re-expressed in certain pathological condition in the adult brain. ► We examine N-cadherin expression in de- and remyelination in an animal model. ► We find N-cadherin expression on oligodendrocytes in early remyelinating lesions. ► In fully remyelinated lesions we did not detect any immunoreactivity for N-cadherin.
Hepatic Candida infection (HCI; known as chronic disseminated candidosis or CDC) is a distinct form of disseminated Candida infection with predominant involvement of the liver. Diagnosis of HCI is ...usually made on clinical suspicion together with multiple lesions in liver on ultrasound (US), CT and/or MRI scan. Fungal elements may not always be visible in liver tissue and mycological culture is frequently negative, making the evidence for proven fungal disease difficult. We studied a novel commercially available low-cost and density-array (LCD) chip technique for a molecular diagnosis of HCI. This is a two-step procedure with PCR amplification after DNA extraction followed by hybridization on a small chip provided by the manufacturer (Fungi 2.1, Chipron GmbH). The analysis of DNA from 45 fungal control strains showed an excellent specificity and sensitivity. The DNA from 11 liver biopsies of patients with haematological malignancies suffering from CDC was analysed on the LCD chip and overall 11 fungal pathogens could be detected in eight liver biopsies, supporting the clinical diagnosis of HCI/CDC. Analysis of liver biopsies from controls was negative for fungal DNA in all samples studied. In conclusion, the novel LCD chip technique examined in our study was able to detect fungal pathogens in liver biopsies from patients with haematological malignancies and suspected HCI/CDC but was negative in control biopsies.
The referral of critically ill cancer patients to an intensive care unit (ICU) is a matter of controversial debate. This study was conducted by an interdisciplinary clinical group to evaluate the ...outcome of ICU treatment in cancer patients according to their characteristics at the time of referral. A retrospective analysis was used to identify relevant subgroups among 189 consecutive cancer patients referred as emergencies to one of four ICUs during a 2-year period. Reasons for ICU referral were pneumonia (29.6%), sepsis (27.0%), fungal infection (11.1%), another infection (9.5%), gastrointestinal emergency (16.9%), treatment-related organ toxicity (6.9%), or other, non-infectious complications (43.9%). Vasopressor support was required in 50.3%, mechanical ventilation in 49.7%, and haemodialysis/-filtration in 26.5% of the patients. Overall, 41.3% died during ICU treatment, 12.2% died after transfer from ICU to a non-ICU ward, and 35.4% were discharged alive. Sepsis, mechanical ventilation, vasopressor support, renal replacement therapy and neutropenia were independent risk factors for fatal outcome, but no single risk factor unequivocally predicted death. All patients with fungal infection who required vasopressor support and either had sepsis (n=13) or needed mechanical ventilation (n=14) died during ICU treatment, while all non-septic patients. who did not require mechanical ventilation, were younger than 74 years of age and had a non-infectious underlying complication (n=29), survived. This analysis may help to early identify relevant subgroups of cancer patients with different prognoses under ICU treatment. A prospective study to confirm the predictive usefulness of this approach is needed. Cancer patients should not be excluded from referral to the intensive care unit in an emergency solely due to their underlying malignant disease or a single unfavourable prognostic factor.
“Magic-sized” nanocrystals (MSNCs) grow in discrete jumps between a series of specific sizes. Consequently, MSNCs have been explored as an alternative route to uniform semiconductor particles, ...potentially with atomic precision. However, because the growth mechanism has been poorly understood, the best strategies to control MSNC syntheses and obtain desired sizes are unknown. Experiments have found that common parameters, such as growth time and temperature, have limited utility. Here, we theoretically and experimentally investigate reactant supersaturation as a tool to control MSNC growth. We compare direct synthesis of CdSe MSNCs with ripening of isolated MSNCs or their mixtures. Surprisingly, we find that MSNCs readily synchronize to the same growth trajectory, even starting from distinct initial conditions, explaining the robustness of MSNC growth. Further, by understanding the synchronization mechanism, we demonstrate methods to control the final MSNC size. These results deepen our knowledge of MSNCs and indicate strategies to tailor their growth.
Hemorrhagic cystitis (HC) is a common complication following high-dose chemotherapy and bone marrow transplantation, and the treatment of virus-associated HC remains to be optimized. This is the ...first report on the successful use of cidofovir in a patient with HC and polyoma viruria concomitant with CMV reactivation after allogeneic BMT. Treatment led to a significant decrease in viruria and to sustained suppression of CMV reactivation. Administered with probenecid and hydration, cidofovir was well tolerated, and there were no side-effects.
•By simultaneously fitting the pre- and post-edge regions of core-level EELS edges, reliable background fits are achieved.•This is beneficial for removing the background from noisy core-level EELS ...spectra.•This method can be extended to multiple EELS edges in a single spectrum.
We present a multi-region extension of power law background subtraction for core-level EEL spectra to improve the robustness of background removal. This method takes advantage of the post-edge shape of core-loss EEL edges to enable simultaneous fitting of pre- and post-edge background regions. This method also produces simultaneous and consistent background removal from multiple edges in a single EEL spectrum. The stability of this method with respect to the fitting energy window and the EELS signal to noise ratio is also discussed.
A new semi-empirical mechanism for n-heptane oxidation and pyrolysis has been developed and validated against several independent data sets, including new flow reactor experiments. Previous ...semi-empirical chemical kinetic mechanisms assumed that a generic n-alkyl radical, formed by abstraction of an H-atom from the parent fuel, thermally decomposes into a fixed ratio of methyl and propene. While such an approach has been reasonably successful in predicting premixed, laminar flame speeds, the mechanism lacks sufficient detail to quantitatively capture transient phenomena and intermediate species distributions. The new chemical kinetic mechanism retains significantly more detail, yet is sufficiently compact to be used in combined fluid-mechanical/chemical kinetic computational studies. The mechanistic approach is sufficiently general to be extended to a wide variety of large linear and branched alkane fuels.
Metal oxide semiconductor nanocrystals (NCs) exhibit localized surface plasmon resonances (LSPRs) tunable within the infrared (IR) region of the electromagnetic spectrum by vacancy or impurity ...doping. Although a variety of these NCs have been produced using colloidal synthesis methods, incorporation and activation of dopants in the liquid phase has often been challenging. Herein, using Al-doped ZnO (AZO) NCs as an example, we demonstrate the potential of nonthermal plasma synthesis as an alternative strategy for the production of doped metal oxide NCs. Exploiting unique, thoroughly nonequilibrium synthesis conditions, we obtain NCs in which dopants are not segregated to the NC surfaces and local doping levels are high near the NC centers. Thus, we achieve overall doping levels as high as 2 × 1020 cm–3 in NCs with diameters ranging from 12.6 to 3.6 nm, and for the first time experimentally demonstrate a clear quantum confinement blue shift of the LSPR energy in vacancy- and impurity-doped semiconductor NCs. We propose that doping of central cores and heavy doping of small NCs are achievable via nonthermal plasma synthesis, because chemical potential differences between dopant and host atomswhich hinder dopant incorporation in colloidal synthesisare irrelevant when NC nucleation and growth proceed via irreversible interactions among highly reactive gas-phase ions and radicals and ligand-free NC surfaces. We explore how the distinctive nucleation and growth kinetics occurring in the plasma influences dopant distribution and activation, defect structure, and impurity phase formation.
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