Ionic groups incorporated into a polymer have a decided effect on its physical properties. A number of ionomers and polyelectrolytes have been widely applied. In particular, sulfonated bisphenol‐A polysulfone (SPSF) has been used as a composite or single‐component membrane for the desalination of water. In this article, the synthesis and physical characteristics of sulfonated polysulfone are addressed. A detailed synthesis route is provided and methods that yield determinable levels of sulfonation are described. These ion‐containing polymers retain an excessive amount of residual salts, which, of course, are impurities to the system. Therefore, before any analyses were made the polymers were subjected to a thorough soxhlet extraction process with boiling water, which appeared to be quite effective. The degree of sulfonation was assessed by several methods such as 1H NMR and FT‐IR. A new 1H NMR method was derived because the method cited in the literature proved to be too inconsistent for our work. The new 1H NMR method used a quaternary ammonium counterion [N(CH3)4]. These methyl protons are easily measured and may be ratioed against the isopropylidene protons in the polymer backbone that act as an internal standard. Characterization of the physical properties of SPSF consisted of water uptake, differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and solubility studies. Its physical appearance and mechanical behavior were improved by the solution procedure. Also addressed were the effects of different counterions (Na+ & Mg++) with SPSFs of low levels of sulfonation. The variation in physical properties between the divalent and monovalent counterions is dramatic, especially when observed by TMA in the rubber plateau above the apparent glass temperature.

Ultrafast light-induced molecular reactions on aerosolized nanoparticles may elucidate early steps in the photoactivity of nanoparticles with potential impact in fields ranging from chemistry and medicine to climate science. In situ morphology discrimination for nanoparticle streams when measuring light-induced reaction yields is crucial, but lacking. Here, we experimentally demonstrate, using the reaction nanoscopy technique, that proton momenta from deprotonation reactions induced by intense femtosecond pulses exhibit clear, distinguishable signatures for single silica nanospheres and their clusters. Our findings are supported by classical trajectory Monte Carlo simulations. The results demonstrate an in situ single-shot discrimination method between reaction yields from photoinduced processes on single particles and their clusters. We find that the ionization of clusters dominates at sufficiently low intensities, providing an explanation to resolve previously observed discrepancies between experimental data and theoretical treatments, which considered only single nanoparticles.

We have synthesized and characterized a new family of low melting allaromatic ester-based liquid crystal oligomers end-capped with reactive phenylethynyl end groups. In a consecutive, high-temperature step, the reactive end groups were thermally activated and polymerization was initiated. This reactive oligomer approach allows us to synthesize liquid crystal thermosets with outstanding mechanical and thermal properties, which are superior to well-known high-performance polymers such as PPS and PEEK. We have modified an intractable LC formulation based on hydroquinone and terephthalic acid, with M n ¼ 1000, 5000, and 9000 g mol À1 , and varied the backbone composition using isophthalic acid, resorcinol, 4hydroxy-benzoic acid, 6-hydroxy-2-naphthoic acid, and chlorohydroquinone. All fully cured polymers showed glass transition temperatures in the range of 164-275 C, and high storage moduli at room temperature ($ 5 GPa) and elevated temperature ($ 2 GPa at 200 C). All oligomers display nematic mesophases and in most cases, the nematic order is maintained after cure. Rheology experiments showed that the phenylethynyl end group undergoes predominantly chain extension below 340 C and crosslinking above this temperature. Highly aligned fibers could be spun from the nematic melt, and we found that the order parameter hP 2 i was not affected by the chain extension and crosslink chemistry.Scheme 2. Synthesis of the terephthalic acid (TA)-and hydroquinone (HQ)-based liquid crystalline oligomers with phenylethynyl end groups. The oligomers in series 1 are terminated with the more linear para-substituted reactive end groups, whereas the series 2 are end capped with the meta-substituted phenylethynyl functionalities. ALL-AROMATIC LIQUID CRYSTALLINE THERMOSETS

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Polimide-block-polydimethylsiloxane (PI-b-PDMS) block copolymers have been synthesized from commercially available amino-terminated polysiloxanes with different molecular weights, for use as polymeric materials resistant to the low earth orbit (LEO) space environment. A structural optimization with respect to maximum environmental protection has been performed by varying the PDMS block length as well as the architecture of the block copolymers spanning from multiblock to triblock and star-shaped morphologies. The synthesized polymers and casted films show good mechanical and thermal performance. For block copolymers with a load of 2% PDMS (in the case of the multiblock copolymers), a complete surface coverage of the PDMS has been found. It has been shown that the transfer of the surface enriched PDMS layer into a thin silica layer after atomic oxygen (AO) exposure results in a drastic decrease in AO erosion rate. The silica layer protects the underlying material from oxygen initiated erosion resulting in a drastic decrease of surface roughness. This phenomena is observable for loads as small as 6 wt % PDMS.

Background:Venous infarction as a complication of microvascular decompression (MVD) is a recognized but extremely rare occurrence in an otherwise standard neurosurgical procedure. Sacrificing one or more veins is considered safe by majority of experienced surgeons and authors. However, in the recent years, there has been growing debate about the management of venous trigeminal compression and/or superior petrosal complex (separation vs. coagulation and cutting of the vein), with few papers describing mild to severe complications related to venous sacrifice.Case Description:We report our dramatic experience during re-exploration for MVD on a male who developed massive cerebellar, brainstem, and brain infarction. Extensive analysis of surgical planning and literature debate about this topic is also reported.Conclusion:Despite rare, venous infarction after venous sacrifice in MVD is possible and can have catastrophic consequences. We would advise: (1) To try preserving the vein anytime this is possible, especially if it is large in size; (2) if it is decided to sacrifice the vein temporary occlusion while observing changed in the neurophysiology might be safer; (3) when planning an MVD for suspected venous compression, possible alternative forms of treatment should also be considered.

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IntroductionAbdominal injuries are responsible for 10% of the mortalities due to trauma. Delays in early diagnosis or misdiagnoses are two major reasons for the mortality and morbidity associated with abdominal trauma. The objectives of this study were to determine the frequency of visceral injuries in patients with abdominal trauma and compare the frequency of visceral injuries in patients with blunt and penetrating abdominal trauma.MethodsWe conducted a cross-sectional study from May 2016 to May 2018 of patients presenting to the emergency department (ED) at Jinnah Postgraduate Medical Center in Karachi, Pakistan. Patients were 12 to 65 years old and presented within 24 hours of abdominal trauma. We recorded the type of abdominal visceral injuries, such as liver, spleen, intestine, stomach, mesentery, and pancreas.ResultsThe mean patient age was 31 ±13 years. Penetrating trauma was found in most patients (n=72, 51%). Liver injuries were found in 37 patients (26.4%), spleen injuries in 29 patient (20.7%), stomach injuries in eight patients (5.7%), intestine injuries in 67 patients (47.9%), mesentery injuries in 21 patients (15%), and pancreas injuries in nine patients (6.4%). The type of abdominal trauma was found significantly associated with liver injury (p-value 0.021), and intestine injury (p-value <0.001).ConclusionPenetrating trauma (51.4%) was more common than blunt trauma (48.5%), and intestines are the most commonly affected by penetrating and blunt trauma injuries (70.1% and 47.8%, respectively). The liver is the most commonly affected (42.85%) in blunt trauma injuries, followed by the spleen (28.5%). The appropriate authorities should consider this information when instituting public health and safety initiatives.