Benzoxazine-Based Thermoset with Autonomous Self-Healing and Shape Recovery

A novel approach is reported for self-healing of polybenzoxazine thermosets based on both supramolecular attractions and metal-ligand interactions. The relating smart material was synthesized by using bis(3-aminopropyl)-terminated polydimethylsiloxane, formaldehyde, and bisphenol A. The films of the obtained main-chain polybenzoxazine precursor (Poly(Si-Bz)) containing 2% FeCl3 were prepared and cured at low temperatures (100-120 degrees C). The structures of the precursors and final products were characterized by spectral analysis. The curing and thermal stability of the related materials were investigated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Self-healing efficiency was studied by stress strain measurements. Potential shape recovery (SR) behavior was also demonstrated by preparing curled or spiral fixed shapes, and the transformation of temporary shapes to these fixed shapes was verified.WOS:0004545674000062-s2.0-8505867119

Katarakt ameliyatında cerrahın monitorizasyonu ve kalp atım hızındaki değişiklikler

PURPOSE: Determining the mental strain and stress of the surgeon and the assistant due to surgery, investigating the recorded heart rate during resting and phacoemulsification surgery MATERIAL AND METHODS: Eleven ophthalmic surgeon (three were female and eight were male) whose the ages ranged from 28-65 (39.9) were included the study. A portable electrocardiography equipment capable of 24 hour recording (Digital ECG Holter recorder) was attached to the surgeon or the assistant to measure the cardiac rhythm. Records were continued along a 15 minute resting period and then surgery/sugeries. Records were analysed in personal computer using SyneView Version 1.01 program accompany with videos simultaneously recorded throug the camera mounted on the surgical microscope. Maximum, minimum, and median heart rates and the changes at different steps of the surgery were noted. RESULTS: Heart rates were recorded in 15 surgery, of which in 11 the Holter recorder was attached to the surgeon while in 4 to the assistant. The mean heart rate was 92.8 /min (minimum 77, maximum 104), and the mean RR distance was 646.5 msn (minimum 576, maximum 779) during resting. With starting of the surgery the mean heart rates were increased and the RR distances shortened in all cases, the same figures were measured as 104.0/ min (minimum 83, maximum 113) and 576.9 msn (minimum 530.9, maximum 722.8). In experienced surgeons with phaco surgeries higher than 200 cases, heart rate differences between resting and surgery periods (8.6/min) were less than medium and less experienced surgeons (16/dk, 15.5/dk, respectively). CONCLUSION: Reaction to the stress is a variable parameter due to individual training, experience, adaptation capability and emotional factors. Therefore mental strain should be objectively determined during the surgery. With this basic approach in the study, it can be concluded that the phaco surgery causes to an objective, measurable mental strain on the surgeon, varying with responsibility and experience.AMAÇ: Dinlenme süresi ve fakoemülsifikasyon cerrahisi boyunca cerrahta ve asiste edende kaydedilen kalp atım hızlarını inceleyerek cerrahinin yarattığı zihinsel gerginliği ve stresi saptamak GEREÇ VE YÖNTEM: Çalışmaya yaş ortalaması 39.9 (28-65 yaş arası), 3'ü kadın 8'i erkek 11 oftalmoloji cerrahı dahil edildi. Kayıt yapılacak cerraha ya da asiste edecek hekime kardiyak ritmini ölçmek amacıyla tüm gün kayıt yapabilen taşınabilir elektrokardiyografi cihazı (Digital ECG Holter recorder) bağlandı. 15 dakikalık istirahat ve ardından cerrahi/cerrahiler boyunca kayıt yapıldı. Kayıtlar bilgisayarda SyneView Version 1.01 programı yardımıyla ve eşzamanlı ameliyat mikroskobuna bağlı kameraya yardımıyla alınan ameliyat videoları eşliğinde çözümlenerek istirahat ve cerrahi boyunca minimum, maksimum ve ortalama kalp atım hızları, ameliyatın farklı evrelerindeki değişiklikler izlendi. BULGULAR: Uygulanan 15 ameliyatta 11 hekimin cerrahiyi gerçekleştirirken, 4 hekimin de asiste ederken kalp atım hızları kaydedilmiştir. Çalışmaya dahil edilen tüm cerrahların istirahat kalp atım hızlarının ortalaması 92.8 /dk (min: 77, max:104) ortalama RR mesafesi 646.5 msn (min:576, max: 779) olarak bulundu. Cerrahiye geçişle birlikte tüm olgularda ortalama kalp atım hızının arttığı ve RR mesafelerinin kısaldığı görüldü, aynı değerler 104.0/dk (min: 83, max: 113) ve 576.9 msn (min:530.9-max: 722.8) olarak saptandı. Olgu sayısı 200'ün üzerinde olan tecrübeli cerrahlarda istirahat ve cerrahi sırasındaki kalp atım hızları farkı (ortalama 8.6/dk) orta derecede veya az tecrübeli cerrahlara (sırasıyla 16/dk, 15.5/dk) göre daha az olarak bulundu. SONUÇ: Stres kaynağına karşın oluşturulan tepki kişinin eğitimine, tecrübesine, şartlara uyum sağlayabilme yeteneğine, ve duygu durumuna göre farklı olacağından cerrahi sırasındaki mental gerginliğin objektif olarak saptanması gerekir. Bunu hedefleyerek yaptığımız bu çalışma, fako cerrahisinde de ameliyatın cerrah üzerinde objektif, ölçülebilir, sorumluluk ve tecrübeyle değişen miktarlarda mental gerginliğe yol açtığını göstermiştir

Data from: Effect of reaction solvent on hydroxyapatite synthesis in sol-gel process

Synthesis of hydroxyapatite (HA) through sol–gel process in different solvent systems is reported. Calcium nitrate tetrahydrate (CNTH) and diammonium hydrogen phosphate (DAHP) were used as calcium and phosphorus precursors, respectively. Three different synthesis reactions were carried out by changing the solvent media, while keeping all other process parameters constant. A measure of 0.5 M aqueous DAHP solution was used in all reactions while CNTH was dissolved in distilled water, tetrahydrofuran (THF) and N,N-dimethylformamide (DMF) at a concentration of 0.5 M. Ammonia solution (28–30%) was used to maintain the pH of the reaction mixtures in the 10–12 range. All reactions were carried out at 40 ± 2°C for 4 h. Upon completion of the reactions, products were filtered, washed and calcined at 500°C for 2 h. It was clearly demonstrated through various techniques that the dielectric constant and polarity of the solvent mixture strongly influence the chemical structure and morphological properties of calcium phosphate synthesized. Water-based reaction medium, with highest dielectric constant, mainly produced β-calcium pyrophosphate (β-CPF) with a minor amount of HA. DMF/water system yielded HA as the major phase with a very minor amount of β-CPF. THF/water solvent system with the lowest dielectric constant resulted in the formation of pure HA

Poly(benzoxazine-co-sulfur): An efficient sorbent for mercury removal from aqueous solution

WOS: 000404690300006A novel sulfur-rich adsorbent, poly(BA-ala-co-sulfur), was synthesized by reacting allyl functional benzoxazine (BA-ala) and elemental sulfur. Simultaneous inverse vulcanization and ring-opening reactions of benzoxazine generated copolymers in several feed ratios. The adsorption behavior of these copolymers was investigated in aqueous solutions containing Hg2+. A three level Box-Behnken design with four factors was applied in order to examine the interactive effect of Hg2+ concentration (ppm), S % in adsorbent, temperature, and pH. The optimum adsorption conditions were determined as: 10.33 ppm Hg2+, 68% S content, 329 K, and pH 6.3. Common isotherm and kinetic models were applied to the experimental data, where the Langmuir isotherm provided the better fit (q(max)=79.36 mg g(-1)) and the pseudo-second order fit indicated chemisorption as the process-controlling step. (C) 2017 Wiley Periodicals, Inc.Science Academy (Turkey); BAGEP; Istanbul Technical University Research FundB.K. thanks to Science Academy (Turkey) for financial support by means of BAGEP award and Istanbul Technical University Research Fund. The authors declare no competing financial interest

XRD diffractogram of THF based synthesis

XRD diffractogram of THF based synthesis. Corresponds to figure (c) in the supplementary data document

Data from: Effect of reaction solvent on hydroxyapatite synthesis in sol-gel process

Synthesis of hydroxyapatite (HA) through sol–gel process in different solvent systems is reported. Calcium nitrate tetrahydrate (CNTH) and diammonium hydrogen phosphate (DAHP) were used as calcium and phosphorus precursors, respectively. Three different synthesis reactions were carried out by changing the solvent media, while keeping all other process parameters constant. A measure of 0.5 M aqueous DAHP solution was used in all reactions while CNTH was dissolved in distilled water, tetrahydrofuran (THF) and N,N-dimethylformamide (DMF) at a concentration of 0.5 M. Ammonia solution (28–30%) was used to maintain the pH of the reaction mixtures in the 10–12 range. All reactions were carried out at 40 ± 2°C for 4 h. Upon completion of the reactions, products were filtered, washed and calcined at 500°C for 2 h. It was clearly demonstrated through various techniques that the dielectric constant and polarity of the solvent mixture strongly influence the chemical structure and morphological properties of calcium phosphate synthesized. Water-based reaction medium, with highest dielectric constant, mainly produced β-calcium pyrophosphate (β-CPF) with a minor amount of HA. DMF/water system yielded HA as the major phase with a very minor amount of β-CPF. THF/water solvent system with the lowest dielectric constant resulted in the formation of pure HA

Discovery of an exceptionally strong luminescence of polyethyleneimine-superparamagnetic iron oxide nanoparticles

Polyethyleneimine (PEI) is rarely recognized as a luminescent polymer but is frequently used for the production of cationic nanoparticles and tagged with an organic fluorophore to be tracked optically. Herein, a strongly luminescent, branched PEI-superparamagnetic iron oxide nanoparticle (bPEI-SPION) without a traditional fluorophore is reported. A tremendous enhancement (1200 times) in the weak blue luminescence of bPEI is achieved only if it is adsorbed on a SPION during the synthesis of nanoparticles, which is improved further upon protonation, irreversibly. This is quite unexpected since SPIONs are strong absorbers in the visible region. All reaction parameters, different synthetic methods, as well as protonation are studied as independent factors to understand the origin of such enhancement. Detailed spectroscopic analysis and density functional theory calculations indicate that partial amine oxidation and Fe3+ reduction takes place during the synthesis, which significantly contributes to the luminescence enhancement. In addition, PEI-SPION exhibits excitation wavelength dependent emission and maintains its magnetic properties

XRD diffractogram of water based synthesis

XRD diffractogram of water based synthesis. Corresponds to figure (a) in the supplementary data document

XRD diffractogram of DMF based synthesis

XRD diffractogram of DMF based synthesis. Corresponds to figure (b) in the supplementary data document