Comparing laser diffraction and optical microscopy for characterizing superabsorbent polymer particle morphology,size, and swelling capacity

In this study, we determined the accuracy and practicality of using optical microscopy (OM) and laser diffraction (LD) to characterize hydrogel particle morphology, size, and swelling capacity (Q). Inverse‐suspension‐polymerized polyacrylamide particles were used as a model system. OM and LD showed that the average particle diameter varied with the mixing speed during synthesis for the dry (10–120 μm) and hydrated (34–240 μm) particles. The LD volume and number mean diameters showed that a few large particles were responsible for the majority of the water absorption. Excess water present in the gravimetric swelling measurements led to larger Qs (8.2 ± 0.37 g/g), whereas the volumetric measurements with OM and LD resulted in reduced capacities (6.5 ± 3.8 and 5.7 ± 3.9 g/g, respectively). Results from the individual particle swelling measurements with OM (5.2 ± 0.66 g/g) statistically confirmed that the volumetric methods resulted in a reduced and more accurate measurement of the Q than the gravimetric method. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46055.     

Magnetic resonance imaging of proximal aortopulmonary window

Of the 187 cases of infantile choledochal cyst treated at our hospitals, we encountered 13 with spontaneous perforation. All cases were under 4 years old. Eight cases were found to have biliary peritonitis and 5 had a sealed perforation. The shape of the extrahepatic bile duct was cystic in 8 and fusiform in 5. The cyst wall around the perforation was filmy and bile was found to be oozing through the thinned wall. Nine perforations were single while 4 cases had multiple perforations. Four of 17 perforations occurred in the posterior part of the cyst wall. Only 1 case of perforation was associated with protein plugs in a common channel, while 7 of the 10 cases of choledochal cyst requiring percutaneous biliary drainage due to signs of raised intrabiliary pressure were found to have protein plugs. We consider that spontaneous perforation of a choledochal cyst is not rare in infancy. The etiology of a perforation must be epithelial irritation of the biliary tract due to refluxed pancreatic juice caused by pancreatico-biliary malunion associated with mural immaturity due to infancy, rather than an abnormal rise in ductal pressure or congenital mural weakness at a certain point.     

Parallel bulk-heterojunction solar cell by electrostatically driven phase separation

Thermal co-evaporation of C(60) fullerene and two merocyanine dyes affords bulk heterojunction solar cells with improved short-circuit currents and power conversion efficiencies in comparison with the respective single donor cells. These results are rationalized by the formation of three distinct subphases driven by differences in molecular shape and electrostatic interactions.     

Efficient Organic Tandem Solar Cells based on Small Molecules

In this paper, two vacuum processed single heterojunction organic solar cells with complementary absorption are described and the construction and optimization of tandem solar cells based on the combination of these heterojunctions demonstrated. The red‐absorbing heterojunction consists of C₆₀ and a fluorinated zinc phthalocyanine derivative (F4‐ZnPc) that leads to a 0.1–0.15 V higher open circuit voltage V_oc than the commonly used ZnPc. The second heterojunction incorporates C₆₀ and a dicyanovinyl‐capped sexithiophene derivative (DCV6T) that mainly absorbs in the green. The combination of both heterojunctions into one tandem solar cell leads to an absorption over the whole visible range of the sun spectrum. Thickness variations of the transparent p‐doped optical spacer between both subcells in the tandem solar cell is shown to lead to a significant change in short circuit current density j_sc due to optical interference effects, whereas V_oc and fill factor are hardly affected. The maximum efficiency η of about 5.6% is found for a spacer thickness of 150‐165 nm. Based on the optimized 165nm thick spacer, effects of intensity and angle of illumination, and temperature on a tandem device are investigated. Variations in illumination intensity lead to a linear change in j_sc over three orders of magnitude and a nearly constant η in the range of 30 to 310 mW cm^?2. Despite the stacked heterojunctions, the performance of the tandem device is robust against different illumination angles: j_sc and η closely follow a cosine behavior between 0° and 70°. Investigations of the temperature behavior of the tandem device show an increase in η of 0.016 percentage points per Kelvin between ?20 °C and 25 °C followed by a plateau up to 50 °C. Finally, further optimization of the tandem stack results in a certified η of (6.07 ± 0.24)% on (1.9893 ± 0.0060)cm² (Fraunhofer ISE), i.e., areas large enough to be of relevance for modules.     

Some aromatic derivatives of 1,4,7,10,13,16-hexaoxacyclooctadecane

Summary Some of the derivatives of polyglycoles were obtained just by reacting the -chlorhydrines with phenols, -naphtol and -naphtols in the presence of NaOH. Derivatives obtained were condensed with the ditosylates of polyethyleneglycoles in the presence of potassium tert-butoxide in THF and some asymmetrical mono and disubstituted hexaoxacyclooctadecanes were formed.Submitted for the fullfilment of Ph.D.degree in Organic Chemistry. Diyarbakir University, 1981     

Arbeiten des Instituts für Hydro- und Aerodynamik der Technischen Hochschule Danzig

Ohne Zusammenfassung VDI     

Rundschau Eine Prüfanlage für Schwingungs- und Beschleunigungsmesser (Schütteltisch).

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