Structural and Chemical Changes to CH3NH3PbI3 Induced by Electron and Gallium Ion Beams

Organic–inorganic hybrid perovskites, such as CH₃NH₃PbI_3, have shown highly promising photovoltaic performance. Electron microscopy (EM) is a powerful tool for studying the crystallography, morphology, interfaces, lattice defects, composition, and charge carrier collection and recombination properties at the nanoscale. Here, the sensitivity of CH₃NH₃PbI₃ to electron beam irradiation is examined. CH₃NH₃PbI₃ undergoes continuous structural and compositional changes with increasing electron dose, with the total dose, rather than dose rate, being the key operative parameter. Importantly, the first structural change is subtle and easily missed and occurs after an electron dose significantly smaller than that typically applied in conventional EM techniques. The electron dose conditions under which these structural changes occur are identified. With appropriate dose‐minimization techniques, electron diffraction patterns can be obtained from pristine material consistent with the tetragonal CH₃NH₃PbI₃ phases determined by X‐ray diffraction. Radiation damage incurred at liquid nitrogen temperatures and using Ga⁺ irradiation in a focused ion beam instrument are also examined. Finally, some simple guidelines for how to minimize electron‐beam‐induced artifacts when using EM to study hybrid perovskite materials are provided.     

A note on ‘Pricing and ordering decisions in a supply chain with imperfect quality items and inspection under buyback of defective items’

Taleizadeh, Noori-daryan, and Tavakkoli-Moghaddam consider pricing and ordering decisions in a three-level supply chain with defective items and inspection processes in their paper published in 2015. They examine three scenarios for defective items at the manufacturer: disposal, rework and selling at a lower price. Unfortunately, this interesting and innovative paper suffers from some shortcomings that are addressed in our note.     

Direct tensile tests on particulate agglomerates for the determination of tensile strength and interparticle bond forces

The importance of direct tensile tests on solid and capillary bonded particulate agglomerates is investigated and compared to compression test measurements. The properties of wet agglomerates are varied by changing the contact angle by means of functionalization of the particle surface. Process conditions are considered by variation of ambient humidity. A qualitative evaluation of the results is performed by analyzing the measured force distance curves of different tensile tests. The results are quantitatively evaluated by calculating the breakage strength, mass related breakage energy and breakage probability showing that the ratio between tensile and compressive tests is highly dependent on the adjusted parameters. Next to the process parameter effect, also the influence of agglomerate size is considered. Tensile strength data are used to estimate the single bond forces between the primary particles of the agglomerates. Tensile and compressive test results are compared to numerical results (DEM) of agglomerate breakage using an elastic stiff bond model.     

Manufacture of fatty alcohols based on natural fats and oils

The present worldwide capacity of fatty alcohols is ca. 1.0 million metric tons per year. About 60% of this capacity is based on petrochemical feedstocks, 40% on natural fats and oils. Three basic dominating commercial-scale processes are used to manufacture fatty alcohols: the Ziegler process and the Oxo synthesis starting from petrochemical feedstocks, and the high-pressure hydrogenation of natural fatty acids and esters. Basically, the high-pressure hydrogenation can be used with triglycerides, fatty acids or fatty acid esters as feedstock. The direct hydrogenation of fats and oils has not been developed to a commercial-scale process, mainly because it was not possible to prevent decomposition of the valuable byproduct glycerol. Conversion of fatty acids into fatty alcohols by catalytic hydrogenation without preesterification requires corrosion-resistant materials of construction and acid-resistant catalysts. Required reaction temperatures are higher, resulting in a higher hydrocarbon content. The majority of fatty alcohol plants based on natural fats and oils use methyl esters as feedstock. These can be made either by esterification of fatty acids or by-transesterification of triglycerides. For catalytic high-pressure hydrogenation of methyl esters to fatty alcohols, several process options have been developed. The bawic distinguishing feature is the catalyst application either in a fixed bed arrangement or suspended in the methyl ester feed.     

Effects of exogenously applied ferulic acid,a potential allelopathic compound,on leaf growth,water utilization,and endogenous abscisic acid levels of tomato,cucumber, and bean

To determine the relative sensitivities of tomato, cucumber, and bean to exogenously applied concentrations of ferulic acid (FA) and to determine whether FA-induced stress responses increase endogenous levels of abscisic acid (ABA), wild-type andFlacca (ABA-deficient mutant) tomato (Lycopersicon esculentum Mill. cv. Ailsa Craig), cucumber, (Cucumis sativus L. cv. Early Green Cluster), and bean (Phaseolus vulgaris L. cv. Oregon 91) were treated with FA (0.0, 0.2, 0.4, 0.8 mM) in nutrient solution every other day for a total of two or three treatments. FA inhibited leaf growth and water utilization of wild-type tomato,Flacca tomato, and cucumber, but not of bean. Acclimation to FA was observed following the first FA treatment and increased endogenous ABA levels were found in wild-type tomato,Flacca tomato, and cucumber following multiple FA treatments. Induction of ABA biosynthesis occurred in wild-type tomato within 8 hr of FA treatment and maximum ABA levels were observed 24 hr after treatment. At that time, ABA levels of tomato treated with 0.4 and 0.8 mM FA were 13.7 times and 2.6 times higher than control levels, respectively. A second FA (0.4 or 0.8 mM) treatment, 48 hr after the first, did not appear to affect ABA levels. Ninety-six hours after the first treatment, ABA levels of tomato treated with 0.4 mM FA approached control levels; ABA levels of plants treated with 0.8 mM FA were 1.9 times higher than control levels. Control ABA levels increased gradually with time. The data showed that plant sensitivity and ability of subsequent acclimation to phenolic acids, such as FA, were taxa dependent.The use of trade names in this publication does not imply endorsement by North Carolina Agricultural Research Service of the products named, nor criticism of similar ones not mentioned.     

Nature conservation and integrated coastal zone management in Europe: present and future

The present and future of integrated coastal zone management (ICZM) in Europe is discussed with an emphasis on nature conservation. The position of nature conservation in physical planning and in legislation is discussed within the historical perspective of the Netherlands. With regard to the present position of nature conservation in planning and legislation, differences in Europe between the northwest, the south and the east are discussed. The roles of various organisations (such as NGOs, GOs, Universities and the European Union) in ICZM is briefly mentioned. The paper advocates a strong position for nature conservation in integrated coastal zone management if it is to be developed on a sustainable basis.     

Absch?tzung der Pyritoxidation in einem Braunkohletagebau mithilfe numerischer Modellrechnungen

Beim Abbau von Braunkohle kann die Oxidation von im Sediment vorhandenen Pyriten zu einer Versauerung des Sickerwassers führen und damit zu einer Mobilisierung von Schwermetallen. Um den Oxidationsgrad der Pyrite in der unbehandelten Abraumkippe eines Braunkohletagebaus abzuschätzen, wurden am Lehrstuhl für Angewandte Geologie der Ruhr-Universität Bochum neben umfangreichen Felduntersuchungen und Laborversuchen auch numerische Simulationsrechnungen durchgeführt. Um die in einem Tagebau oxidierten Pyritmengen zu berechnen, wurde mithilfe des numerischen Modells gw-chem.f sowohl die Oxidation auf der Abbauseite als auch die Oxidation auf der Kippenseite berechnet. Die genaue Kenntnis der umgesetzten Pyritmenge ist notwendig, um die Kalkmenge zu ermitteln, die benötigt wird, um die bei der Pyritoxidation entstehende Schwefelsäure zu neutralisieren. Dadurch soll das Grundwasser geschützt werden, wenn der Tagebau wieder geflutet wird.     

Carbon nanotubes and mesenchymal stem cells: biocompatibility, proliferation and differentiation

The synergy of the unique properties of carbon nanotubes (CNT) with the remarkable potential of human mesenchymal stem cells (hMSC) provides an exciting opportunity for novel therapeutic modalities. However, little is known about the impact of CNT on hMSC behavior. We report the effect of CNT on hMSC renewal, metabolic activity, and differentiation. Furthermore, we tracked the intracellular movement of CNT through the cytoplasm to a nuclear location and assessed effects on cellular ultra structure.