Ultrastructure of Capillaries in Mouse Periodontium

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67294/2/10.1177_00220345760550034001.pd

Cost analysis of blasting agents at various methods of initiation for shooting long holes method

W pracy porównano zmianę kosztów środków strzałowych dla przyjętego modelu: określonych warunków geologiczno‒górniczych, dwóch różnych materiałów wybuchowych, zmiennych parametrów geometrycznych otworu oraz wartości parametrów strzałowych; zakładając prowadzenia prac strzelniczych metodą otworów długich. Symulacje przeprowadzono dla trzech systemów inicjowania w celu zobrazowania zmian relacji kosztów materiałów wybuchowych do środków inicjujących w zależności od przyjętego systemu. Ponadto przedstawiono sumaryczne koszty prowadzenia prac strzałowych oraz koszty jednostkowe dla przyjętych założeń. Przedstawiono wnioski dotyczące zmieniających się kosztów prowadzenia prac strzałowych przy różnych sposobach inicjowania i zmieniających się parametrach strzelania.The evaluation of changes in the cost of blasting for adopted model, specific geological and mining conditions, two different explosives, variable parameters and geometric hole blasting parameters, assuming its work by firing long holes was presented. Simulations were performed for three initiating systems to imaging changes in the cost-explosives initiators, depending on a system. Also shows the total cost of doing the work of blasting and unit costs for the assumptions. The conclusions regarding the changing costs of blasting work at different ways of initiating and changing shooting parameters were presented

Technological possibilities of reducing scattering range zone in opencast mining

W artykule scharakteryzowano najczęstsze przyczyny i czynniki mające wpływ na poza normatywny zasięg oddziaływania rozrzutu ze szczególnym uwzględnieniem zaburzeń budowy geologicznej wyrobiska. Przedstawiono sposób oceny zagrożenia rozrzutem odłamków w wyniku zaistniałych zróżnicowanych warunków strzelania na różnych wysokościach ociosu. Opisano sposoby zapobiegania rozrzutowi omówione na przykładach konkretnych warunków geologiczno-górniczych ze szczególnym uwzględnieniem problemów wynikających z prowadzenia prac strzałowych przy likwidacji progów przyspągowych oraz działania profilaktyczne: techniczne i organizacyjne stosowane w celu kontroli i ograniczenia tego zjawiska.The article describes the most common causes and factors increased scatter range with particular focus on disorders of the geological structure. An assessment of risks scatter rock fragments as a result of different conditions shooting occurred at different heights side wall were presented. Discussed methods for scatter preventing and prevention measures: technical and organizational used to limit and control this phenomenon

Towards Controlled Degradation of Poly(lactic) Acid in Technical Applications

Environmental issues urge for the substitution of petrochemical-based raw materials with more environmentally friendly sources. The biggest advantages of PLA over non-biodegradable plastics are that it can be produced from natural sources (e.g., corn or sugarcane), and at the end of its lifetime it can be returned to the soil by being composted with microorganisms. PLA can easily substitute petroleum-based plastics in a wide range of applications in many commodity products, such as disposable tableware, packaging, films, and agricultural twines, partially contributing to limiting plastic waste accumulation. Unfortunately, the complete replacement of fossil fuel-based plastics such as polyethylene (PE) or poly(ethylene terephthalate) (PET) by PLA is hindered by its higher cost, and, more importantly, slower degradation as compared to other degradable polymers. Thus, to make PLA more commercially attractive, ways to accelerate its degradation are actively sought. Many good reviews deal with PLA production, applications, and degradation but only in the medical or pharmaceutical field. In this respect, the present review will focus on controlled PLA degradation and biodegradation in technical applications. The work will include the main degradation mechanisms of PLA, such as its biodegradation in water, soil, and compost, in addition to thermal- and photo-degradation. The topic is of particular interest to academia and industry, mainly because the wider application of PLA is mostly dependent on discovering effective ways of accelerating its biodegradation rate at the end of its service life without compromising its properties

Results of a factor analysis of items regarding COVID-19 pandemic-specific workload among medical staff in Germany

INTRODUCTION: Epidemics lead to an increase in occupational stress and psychological strain among medical staff (cf. Mulfinger et al. 2020). However, there are no validated questionnaires to measure stress caused by an epidemic such as Covid-19, instead self-constructed questions are used frequently. OBJECTIVES: The aim was to develop items for the assessment of specific workload in epidemics which can be used to obtain longitudinal data. METHODS: A sample of N=8078 persons working in the health care sector in Germany participated in the VOICE, EviPan online survey addressing the burden of Covid-19 pandemic during the 2nd quarter of 2020. We used 15 self-constructed items to examine whether these items can represent Covid-19 specific topics. A total of N=7549 (24% males) had complete data to run a confirmatory factor analysis using SEM procedure in Stata 14.2. RESULTS: Five factors were identified a priory: Factor (F) 1: Workload due to Covid-19 pandemic (4 items; Cronbachs’ alpha (α))=0.740); F 2: Fear, uncertainty of SarsCoV-2infection (self and others) (3 items; α= 0.741); F 3: Patient safety (3 items; α=0.533; F 4: Perception of protection concepts (2 items; α=0.590); F 5: Dysfunctional coping strategies (3 items; α=0.447). Fit-Indices: χ²(73)= 1373.849, p<.001, CFI=.946, TLI=.923, RMSEA=.0049, SRMR=.037) CONCLUSIONS: We identified 5 factors associated with problems occurring during the Covid-19 pandemic with acceptable to good internal consistency. Most of the constructed items could therefore be used in further surveys to monitor stress, as a basis for recommendations in the area of stress prevention and interventions for medical staff during epidemics