An investigation of catalyt preparation conditions and promoter loading (Sn) effects on activity and selectivity of Pt catalyists in citiral hydrogenation

Thesis (Master)--Izmir Institute of Technology, Materials Science and Engineering, Izmir, 2010Includes bibliographical references (leaves: 52-54)Text in English; Abstract: Turkish and Englishx, 59 leavesIn this study, citral hydrogenation reaction in liquid phase over silica gel supported Pt and PtSn catalysts were studied. It was desired to hydrogenate carbonyl group (C.O) selectively to produce valuable unsaturated alcohols, namely nerol, geraniol and citronellol. Pt/SiO2 catalysts were prepared by impregnation method while PtSn/SiO2 catalysts were prepared by catalytic reduction (CR), co-impregnation (CI) and successive impregnation (SI) methods. Pt loading over silica gel support was 1 % (w/w). For bimetallic catalysts, the (Sn/Pt) loading ratios were varied as 0.3, 0.5 and 0.7. The effects of parameters investigated in the present study included catalyst activation temperature (350 °C, 450 °C), calcination temperature (400 °C, 500 °C), solvent type (ethanol, 2-pentanol), catalyst activation without calcination, washing of catalyst with 0.1 M NaOH solution, Pt precursor type (hexachloroplatinic acid, platinum II acetylacetonate (PAA)) and Sn loading ratio. For Pt/SiO2 catalysts, maximum citral conversion (89 %) was achieved at lower activation (350 °C) and calcination (500 °C) temperatures when PAA was used. Increasing the activation temperature to 450 °C decreased the citral conversion to 52 % but increased the selectivity to unsaturated alcohols (nerol and geraniol) (SNE+GE) from 8 % to 60 %. It was observed that the lower activation temperature provided higher citral conversion but lower selectivity to unsaturated alcohols. Washing of catalyst and using of 2-pentanol prevented the acetal formation. Catalyst activated without calcination step gave lower conversion (20 %) and SNE+GE of 30 %. For bimetallic catalyst (PtSn/SiO2), maximum citral conversion was observed as 91.1 % when catalyst was prepared by CR method and calcined at 500 °C. Higher citral conversion and selectivity to unsaturated alcohols were achieved at the higher calcination temperature and higher reduction temperature. CR method was the most appropriate preparation method for bimetallic catalysts compared to CI and SI. An optimum of activity (91.1 %) and selectivity (89.7 %) was found at a Sn/Pt ratio 0.5

Einfluss von Glukose auf die HMGB-1-Regulation der ß-Inselzellen

In der vorliegenden Arbeit wurde der Einfluss von Glukose auf die HMGB1-Regulation von Glukose der ß-Inselzellen untersucht. INS-1 Zellen, die mit 10 und 30 mM Glukose behan-delt wurden, wurden mittels 2 D-Gelelektrophorese aufgetrennt. Wir untersuchten die Pro-teine HMGB1 und Caspase 3, die anschließend mit Hilfe von Westernblot verifiziert wur-den. Unter der Hyperglykämie zeigte sich eine Herunterregulation von HMGB1 sowie eine Aktivierung von Caspase 3. Ferner wurde mit Hilfe von MTT-Assays unter hypergly-kämischen Bedingungen eine signifikante Abnahme der Zellproliferation nachgewiesen. Bei der Zellfraktionierung konnte unter erhöhter Glukosebelastung eine Reduktion von HMGB1 sowohl im Zellkern als auch im Zytosol dargestellt werden. Eine zusätzliche Be-handlung mit Pioglitazon konnte interessanterweise eine Herabregulation von HMGB1 verhindern. Die mit 10 mM Glukose und Pioglitazon behandelten INS-Zellen zeigten eine deutliche Unterexpression bzw. eine starke Beeinträchtigung der Zellproliferation. In Anbe-tracht dessen entfaltet Pioglitazon seine protektive Wirkung unter erhöhten Glukose-bedingungen. Bei den Diabetikern wurden vor und nach der Pioglitazonbehandlung er-niedrigte HMGB1-Spiegel nachgewiesen. Eine Erhöhung der HMGB1-Spiegel konnte un-ter Einfluss von Pioglitazon nicht erzielt werden. In der Zusammenschau der Befunde ist anzunehmen, dass Pioglitazon seine protektive Wirkung erst im fortgeschrittenen Stadium des Diabetes Mellitus entfaltet. Desweiteren entfaltet Pioglitazon seine protektive Wirkung auf die Karzinomzellen, so dass ein Harn-blasenkarzinom oder Kolonkarzinom verursacht wird. In Anbetracht dessen wurden Glitazone 2011 vom Markt genommen. Pioglitazon soll aber ggf. bei MS wirksam sein. Um mögliche antiapoptotische Funktionen von HMGB1 zu untersuchen, wurde mittels RT-PCR eine Klonierung, dann eine stabile Transfektion durchgeführt. In den durchgeführten Westernblots zeigte sich eine leichtgradige HMGB1-Überexpression. Wir gingen von einer leichten Überexpression aus, da sich die stabil transfizierten INS-1 Zellen im Vergleich zu den normalen INS-1 Zellen anders verhielten. Unter erhöhten Glukosekonzrentrationen stellte sich keine Herunterregulation der HMGB1-Bande dar und die Zellproliferation der INS-1 Klone war deutlich gebessert. Eine Caspase 3-Spaltung konnte unter erhöhten Glukosebedingungen nicht nachgewiesen werden, somit verhindert eine HMGB1-Überexpression die Aktivierung von Caspase 3

COVID-19 Pandemi Sürecinde Sağlık Çalışanlarının Beslenme Alışkanlıklarındaki Değişikliklerin Değerlendirilmesi

Objective: The workload and working hours of healthcare professionals have increased due to the COVID-19 pandemic. The aim of this study was to evaluate how COVID-19 outbreak restrictions affect dietary habits among healthcare professionals. Material and Method: The study population was 239 adults aged between 18-65 years. An online survey including questions about demographic variables, health information, lifestyle behaviors, and dietary habits were sent via an online platform. Self-reported weight, and height before and during the pandemic were also collected. Results: The percentage of those who skip the main meals during the lockdown (48.1%) has increased compared to before the lockdown (43.9%). The most skipped main meal and snack were breakfast and mid-morning, respectively. Among the study population, 48.1% reported that they increased their vegetable-fruit consumption, 38.1% reported increased water intake and 45.6% reported consuming more home-cooked food. The most preferred snacks were fruits-vegetables (62.3%), and nuts (55.6%). Approximately half of the participants (46.0%) reported an increased appetite and 50.6% of the participants stated an increase in body weight during COVID-19. The weight gain of the 51-64 age group (3.73±4.13 kg) was statistically significantly higher than the 18-50 age group (0.43±4.51 kg) (p=0.014). The rate of those who reported doing at least 150 minutes of exercise per week before COVID-19 (43.9%) decreased during the pandemic (30.5%). Conclusion: Body weight, appetite, some dietary habits, and physical activities were generally adversely affected among healthcare workers during the pandemic. Older groups are most prone to weight gain during the lockdown.This research was funded by The Scientific and Technological Research Council of Turkey (TUBITAK) 2209-A Projects Funding Program, grant number: 1919B01200108

Effects of catalyst precursor type and preparation conditions, and solvent type on activity and selectivity of Pt/SiO2 catalyst in citral hydrogenation

In this study, citral hydrogenation reaction in liquid phase over silica gel supported Pt catalysts was investigated. It was desired to hydrogenate carbonyl group selectively to produce valuable unsaturated alcohols, namely geraniol and nerol. Pt/SiO2 catalysts were prepared by impregnation method. The effects of parameters investigated in the present study included Pt precursor type (hexachloroplatinic acid (HCLPA), platinum II acetylacetonate (PAA)), catalyst activation temperature (350°C and 450°C), catalyst activation without calcination, catalyst washing with 0.1 M NaOH and solvent type (ethanol, 2-pentanol). The catalysts activities and selectivities were affected by the type of precursor and activation temperature. The maximum citral conversion (89.50 percent) was achieved at lower activation temperature (350°C) with PAA precursor based catalyst. It was observed that higher activation temperature provided lower citral conversion but higher selectivity to unsaturated alcohols; increasing the activation temperature to 450°C decreased citral conversion to 26.10 percent. But selectivity to unsaturated alcohols, geraniol and nerol, increased from 7.06 to 54.60 percent. Catalyst washing and 2-pentanol prevented acetal formation. Catalyst activation without calcination gave lower citral conversion (20.84 percent) and selectivity to unsaturated alcohols (30.00 percent). Copyright © 2011 The Berkeley Electronic Press. All rights reserved.Izmir Institue of Technology (2010 IYTE04

Current Overview of the Ketogenic Diet Effecst on Refractory Epilepsy

Epilepsi; nöbetler ile karakterize bir hastalıktır. Epilepsi hastalarının çoğunda nöbetler anti epileptik ilaçlar kullanılarak kontrol edilebilmektedir ancak dirençli epilepsi olarak adlandırılan epilepsi türünde, ilaçlar nöbet kontrolü üzerine etkili değildir. Buna ek olarak, bazı hastalarda ilaçların istenmeyen yan etkileri, antiepileptik ilaç kullanımının kesilmesine neden olmaktadır. Bu ve benzeri durumlarda, farmakolojik bir tedavi türü olmayan ketojenik diyet, alternatif tedavi yöntemi olarak önerilmektedir. Ketojenik diyetin epilepsi tedavisinde etkin rol oynayabileceğini düşündüren temel gerçeklik ise, nöronlar için ana enerji substratı olan glikoz yerine, açlık gibi bazı durumlarda keton cisimlerinin kullanılıyor olmasıdır. Keton cisimlerinin oluşmasını sağlayan ancak ketojenik diyete uygulama kolaylığı ve esnekliği sağlaması adına farklı ketojenik diyet türleri oluşturulmuştur. Dirençli epilepsi tedavisinde hastaların tolere edebilirliğine göre bu ketojenik diyet yaklaşımları kullanılabilmektedir. Bu derlemede, ketojenik diyet ve türlerinin dirençli epilepsi üzerine etkisinin derlenmesi amaçlanmıştır.Epilepsy is a disease characterized by seizures. In most patients with epilepsy, seizures can be controlled using anti-epileptic drugs, but in the type of epilepsy called resistant epilepsy, drugs are not effective on seizure control. In addition, the undesirable side effects of antiepileptic drugs in some patients lead to the cessation of antiepileptic use. In these and similar cases, the ketogenic diet, which is not a pharmacological treatment type, is considered as an alternative treatment method. The basic reality suggesting that the ketogenic diet can play an effective role in the treatment of epilepsy is that instead of glucose, which is the main energy substrate for neurons, ketone bodies are used in some cases such as hunger. Again, different ketogenic diets have been created to enable the formation of ketone bodies and provide ease and flexibility to the ketogenic diet. Depending on the tolerability of patients in the treatment of epilepsy, one of these ketogenic diet variations can be used. This review was conducted to evaluate the effect of ketogenic diet on epileps

Numerical modeling of compression strengths of ti6al4v gyroid structures produced by laser powder bed fusion technology

Ortopedik metal implantlar fonksiyonun geri kazanılması amacıyla eklem ve kemik dokusunun onarımı sürecinde sağlamlığı korumak için yaygın kullanılır. İmplantların yük taşıma işlevi gören bölgeye uygun elastik modül değeri ve vücutta oluşacak olumsuz etkileri önleyici biyouyumluluk özelliklerinin olması, minimum gereksinimlerdir. İdeal implant malzemesi üzerine yaygınlaşmış çalışmalar, yüksek mekanik dayanıklılık ve osteointegrasyon özellikleri nedeniyle titanyum ve titanyum alaşımlı implantlar üzerinedir. Ancak implantasyon sonrası vücutta kalması istenen durumlarda biyoaktiviteyi daha da artırmak ve kemiğin mekanik özelliklerine yaklaşmak amacıyla üçlü periyodik minimal yüzey (ÜPMY) kafes yapısına sahip gözenekli implantlar kullanılır. Çalışma, istenen mekanik özellikleri ve gözenekler arası hücre hareketini sağlamak için kontrollü ÜPMY kafes yapılarından gyroid gözenek yapısına sahip lazer toz yatağında füzyon ile üretimi planlanan Ti6Al4V ilk olarak 40-80% arasında farklı gözeneklilik oranlarında tasarlanmıştır. Ardından her bir tasarım için basma altında mekanik dayanım ve deformasyon davranışlarını sonlu eleman analizi altında incelemeye odaklanılmıştır. Literatüre bakıldığında lazer toz yatağında füzyon ile üretilen gyroid Ti6Al4V yapıların basma testi sonuçları ile karşılaştırılmış ve uyumlu sonuçlar alınmıştır.Metal orthopedic implants are widely used to maintain stability during tissue repair in joint and bone injuries to restore function. Elastic modulus values suitable for the area where the implants carry the load-bearing part and have biocompatibility features that prevent harmful effects on the body are the minimum requirements. Widespread studies on the ideal implant material are on titanium and titanium alloy implants due to their high mechanical strength and osteointegration properties. However, in cases where it is desired to remain in the body after implantation, porous implants with triply periodic minimal surface (TPMS) lattice structures are used in order to increase the bioactivity further and reach the mechanical properties of the bone. In the study, Ti6Al4V with gyroid pore structure, one of the controlled TPMS lattice structures planned to be produced by laser powder bed fusion technology, was designed with different porosity rates between 40-80%. Then, the focus is on examining the mechanical strength and deformation behaviors under compression for each design with the finite element analysis. The results of the study were compared with the compression test of gyroid Ti6Al4V structures produced by laser powder bed fusion from the literature and consistent results were obtained

Thin-walled commercially pure titanium structures: laser powder bed fusion process parameter optimization

Laser powder bed fusion (L-PBF) process parameters can be changeable depending on the part geometry due to thermal conductivity differences. The number of studies on the process parameter development for commercial pure titanium (Cp-Ti) with the L-PBF process is also quite limited in the literature. The aim of this study is to present a comprehensive process development for the production of Cp-Ti bulk and thin structures with the L-PBF technology. In the first phase, the right process parameters, including scan speed, laser power, hatch distance, and layer thickness, were identified with prismatic specimens with thin walls so that the obtained parameters could be used for both bulky sections and thin features such as lattice structures. The process parameters were varied to change the volumetric energy density from 19 to 208 J/mm3 among 80 different parameter sets. Parameter sets having a Volumetric Energy Density (VED) value between 32 J/mm3 and 47 J/mm3 gave almost fully dense Cp-Ti parts while the laser power was set to 200–250 W and the scan speed was used as 1000–1400 mm/s. Finally, Vickers hardness and tensile tests were applied to highly dense Cp-Ti parts. This study involving investigating the effect of process parameters on a wide range demonstrated that L-PBF is a favorable manufacturing technology for Cp-Ti parts with almost full density and good mechanical properties as well as good dimensional accuracy even on thin geometries. Moreover, the results show that combining parameters into a single one, i.e., VED, is not a proper way to optimize the process parameters since increasing laser power or decreasing the scan speed may alter the results, although VED is increased in both manners

Titanium based bone implants production using laser powder bed fusion technology

Additive manufacturing (AM) enables fully dense biomimetic implants in the designed geometries from preferred materials such as titanium and its alloys. Titanium aluminum vanadium (Ti6Al4V) is one of the pioneer metal alloys for bone implant applications, however, the reasons for eliminating the toxic effects of Ti6Al4V and maintaining adequate mechanical strength have increased the potential of commercially pure titanium (cp-Ti) to be used in bone implants. This literature review aims to evaluate the production of cp-Ti and Ti6Al4V biomedical implants with laser powder bed fusion (L-PBF) technology, which has a very high level of technological matureness and industrialization level. The optimization of L-PBF manufacturing parameters and post-processing techniques affect the obtained microstructure leading to various mechanical, corrosion and biological behaviors of the manufactured titanium. All of the features are considered in the light of specifications and needs of bone implant applications. The most critical disadvantages of the L-PBF technology, such as residual stresses and leading deformations are introduced and the potential solutions are discussed. Moreover, the manufacturability of porous bone implants that causes benefit and harm in L-PBF applications are assessed.Peer ReviewedObjectius de Desenvolupament Sostenible::3 - Salut i BenestarPostprint (published version