Low Temperature Precursor Route for Highly Efficient Spherically Shaped LED-Phosphors M2Si5N8:Eu2+ (M = Eu, Sr, Ba)

The highly efficient nitridosilicate phosphors M2Si5N8 (M = Sr, Ba, Eu) for phosphor-converted pc-LEDs were synthesized at low temperatures using a novel precursor route involving metal amides M(NH2)2. These precursors have been synthesized by dissolution of the respective metals in supercritical ammonia at 150°C and 300 bar. The thermal behavior and decomposition process of the amides were investigated with temperature programmed powder X-ray diffractometry and thermoanalytical measurements (DTA/TG). These investigations rendered the amides as suitable intermediates for reaction with silicon diimide (Si(NH)2). Thus, the desired nitridosilicate phosphors were obtained at relatively low temperatures around 1150−1400°C which is approximately 300°C lower compared to common synthetic approaches starting from metals or oxides. The influence of the thermal treatment on the phosphor morphology has been studied extensively. The accessibility of spherical phosphor particles represents another striking feature of this route since it improves light extraction from the crystallites due to decreasing light guiding and decreasing re-absorption inside the phosphor particle. The synthesized luminescent materials M2Si5N8:Eu2+ (M = Sr, Ba) exhibit quantum efficiencies and emission band widths (FWHM 70−90 nm) comparable to standard phosphor powders. Employment of Eu(NH2)2 as dopant reagent for synthesis of Ba2Si5N8:Eu2+ proved favorable for the formation of spherical crystallites compared to doping with Eu metal, halides, or oxide

In situ powder X-ray diffraction during hydrogen reduction of MoO3 to MoO2

The hydrogen reduction of molybdenum trioxide to molybdenum dioxide is not yet fully understood as evident by continuous scientific interest. Especially the effect of the potassium content on the reduction process has not yet been considered. We prepared several samples of molybdenum trioxide containing varying amounts of potassium by addition of potassium molybdate (K2MoO4). In situ powder X-ray diffraction experiments were then conducted to study the hydrogen reduction of these samples. We especially focused on the influence of the alkali content and on gaining insight into the importance of the intermediary product γ-Mo4O11. During the reduction process, MoO2 is formed from the reduction of MoO3, which then reacts with the starting material to form γ-Mo4O11. With increasing potassium content, the reduction rate is decreased and the fractional content of γ-Mo4O11 built up during the reduction process is increased. As evident from bulk sample reduction, this results in a significant increase in the grain size visualized via scanning electron microscopy. Our investigations once again underline the importance of γ-Mo4O11 on the morphology of the resulting MoO2 powder

Solar energy for self-contained power supply

Solar energy relevance in self-contained utility system as well as economic feasibility for each class of consumers considered. The article will outline utilising features of self-contained photovoltaic stations in Middle East and Northern Africa

The effectiveness of interventions in workplace health promotion as to maintain the working capacity of health care personal

Background: The increasing proportion of elderly people with respective care requirements and within the total population stands against aging personnel and staff reduction in the field of health care where employees are exposed to high load factors. Health promotion interventions may be a possibility to improve work situations and behavior. Methods: A systematic literature search is conducted in 32 databases limited to English and German publications since 1990. Moreover, internet-searches are performed and the reference lists of identified articles are scanned. The selection of literature was done by two reviewers independently according to inclusion and exclusion criteria. Data extraction and tables of evidence are verified by a second expert just like the assessment of risk of bias by means of the Cochrane Collaboration’s tool. Results: We identified eleven intervention studies and two systematic reviews. There were three randomized controlled trials (RCT) and one controlled trial without randomization (CCT) on the improvement of physical health, four RCT and two CCT on the improvement of psychological health and one RCT on both. Study duration ranged from four weeks to two years and the number of participants included from 20 to 345, with a median of 56. Interventions and populations were predominantly heterogeneous. In three studies intervention for the improvement of physical health resulted in less complaints and increased strength and flexibility with statistically significant differences between groups. Regarding psychological health interventions lead to significantly decreased intake of analgesics, better stress management, coping with workload, communication skills and advanced training. Discussion: Taking into consideration the small to very small sample sizes, other methodological flaws like a high potential of bias and poor quality of reporting the validity of the results has to be considered as limited. Due to the heterogeneity of health interventions, study populations with differing job specializations and different lengths of study durations and follow-up periods, the comparison of results would not make sense. Conclusions: Further research is necessary with larger sample sizes, with a sufficient study duration and follow-up, with a lower risk of bias, by considering of relevant quality criteria and with better reporting in publications

Ultrasound guided regional anesthesia: What we know, what we think we know, what we don't know yet: Running title USGRA: Overview about facts and questions: An educational narrative review of literature

The introduction of ultrasound guidance over the last two decades brought progress, new blocks and new challenges to Regional Anesthesia. This narrative review addresses and discusses facts, frequent questions, beliefs, controversies, unsolved issues, open safety questions and existing knowledge gaps related to efficacy and safety of ultrasound guided regional anesthesia (USGRA), based on the available literature. We discuss evidence-based advantages and limitations of ultrasound guidance, as well as unresolved questions, with respect to successful anesthesia, undesired side effects and patient safety, like nerve injury and local anesthetic systemic toxicity (LAST). In an educational approach we also emphasize some practical aspects of our everyday experience as well as necessary structural requirements

Avoiding pitfalls in antibiotic therapy: the antibiotic stewardship approach

The aim of this reflection is to determine the effectiveness and safety of ABS interventions. A strong correlation between antibiotic overuse and the growing worldwide resistance, but also with individual side effects is well established and should open the door to a more personalized approach to anti-infective therapies. Antibiotic resistance is a global public health challenge and is recognized as a global threat to human health by national healthcare agencies, governments, medical societies and the World Health Organization (WHO). The anticipated clinical scenario of Pan- Drug – Resistant (PDR) bacteria is accelerated by antibiotic overuse. In fact, multi- drug – resistance (MDR) is already the cause of severe infections, complications, longer hospital stay and increased mortality in most of the countries. Herein, the techniques of an Antibiotic Stewardship Approach and their stepwise implementation are summarized and highlighted. There is often a general lack of understanding on how to choose the right antibiotic at the right time and in the right dose. This article discusses general principles like the best choice and use of different antibiotic classes, a better use of beta- lactams according to principles of pharmacokinetics, avoidance or limitation of unnecessary combination therapies, shorter courses of therapy without any disadvantage in infection control and the value of PCT monitoring. We hope to contribute to the promotion and implementation of these important therapeutical principles, aiming at the reduction of unnecessary or wrong antibiotic therapies and, so, at the decrease of side effects, mortality and further resistance.

Influence of lactococcal surface properties on cell retention and distribution in cheese curd

During cheese manufacturing, on average 90% of the starter culture cells are believed to be entrapped in the curd, with the remainder lost in whey. This paper shows that plasmid-cured dairy strains of Lactococcus lactis show cell retention in the curd of 30-72%, whereas over-expression of pili on the lactococcal cell surface can increase cell retention to 99%. Exopolysaccharide production and cell clumping and chaining do not influence cell retention in cheese curd. L. lactis surface alteration also strongly affected the distribution of cells in the cheese matrix: clumping and over-expression of pili led to formation of large cell aggregates embedded in the protein matrix whereas exopolysaccharide expression resulted in cells being surrounding by small serum regions in the protein matrix of the cheese. These results suggest that surface properties of dairy starter cultures strongly determine retention and distribution of the bacteria in cheese curd. (C) 2018 The Authors. Published by Elsevier Ltd