Effect of pore-forming agents on microstructure in La-BaTiO3 ceramics

Yüksek porozite ve elektriksel direnç, seramik esaslı sensör malzemelerin ana karakteristiklerinden birisi olup sinterleme parametrelerinin değişimi ve La+3 dop etme ile BaTiO3 yapısına söz konusu özellikler kazandırılabilmektedir. BaTiO3 esaslı seramiklerin elektriksel özellikleri, söz konusu seramiklerin çeşitli uygulama alanları ve elektriksel davranışının açıklanmasındaki güçlükler nedeniyle, günümüzde ilgi çekici bir araştırma konusu olmaya devam etmektedir. BaTiO3 esaslı seramiklerde elektriksel direnç, perovskit kafeste baryum veya titanyum konumlarına nadir toprak elementleri dop edilerek etkin şekilde kontrol edilebilmektedir. Porozite yapıcılar ile katkılandırma yönteminin de, sensör uygulamalarında kullanılacak poroz seramiklerin üretiminde etkili bir yöntem olduğu bilinmektedir. Bu çalışmada, grafit ve PMMA (Polimetil metakrilat) katkılarının La+3 katkılı BaTiO3 esaslı seramiklerin porozite özellikleri üzerine etkileri incelenmiştir. Farklı bileşimlerde grafit ve PMMA katkıları içeren örnekler için porozite çalışmaları ve mikroyapısal karakterizasyon yapılmıştır. BaTiO3 esaslı seramiklerde porozite yapıcı katkı türünün porozite ve mikroyapısal özellikler üzerine etkisi incelenmiştir. Buna göre, porozite yapıcı katkılar veya donör katkısının yapıda ikincil bir faz oluşturmadığı belirlenmiştir. PMMA katkısının, grafit katkısına göre daha yüksek porozite yüzdesi ve büyük por boyutları oluşturduğu gözlenmiştir. Grafit katkısı, ekzotermik reaksiyonlar nedeniyle tane büyümesine neden olmuştur ancak tane morfolojisinde belirgin herhangi bir değişim gözlenmemiştir. PMMA ile katkılandırılmış örneklerde ise tane boyutu incelmiştir. Üretilen BaTiO3 esaslı poroz seramiklerin, gaz veya nem sensörü uygulamalarında kullanılmaya elverişli olduğu belirlenmiştir.   Anahtar Kelimeler: BaTiO3, porozite, sensör, grafit, PMMA.High porosity and electrical resistance are among the main characteristics of ceramic based sensor materials, which are obtained by the variation of sintering parameters and La+3 doping for BaTiO3. Addition of pore-forming agents (PFA) is also an effective method to fabricate porous ceramics for sensor applications. Several approaches have been done recently for manufacturing porous ceramics. It has been reported that porous BaTiO3 can be prepared by the incorporation of graphite, polyvinylalcohol (PVA), polyvinylbutyral (PVB), borides, silicides, carbides, corn-starch, potato-starch and partially oxidized titanium powder addition to BaTiO3 or by the thermal decomposition of barium titanyl oxalate BaTiO(C2O4)2-4H2O. Oxygen can be adsorbed at the grain boundaries due to the presence of pores in the porous ceramics, which are more favorable to form surface acceptor states compared with ordinary dense ceramics. The addition of organic particles, which vaporize at relatively low temperatures forming small and homogeneously distributed pores, is one of these methods. Porous structures having gas / liquid permeability, which can serve as gas or humidity sensors, could be fabricated via this method. The electrical properties of BaTiO3 based ceramics are still a matter of considerable interest due to their various applications and the difficulty in explaining the electrical behaviour. The electrical resistance of BaTiO3 based ceramics can be controlled effectively by rare earth doping into the barium or titanium sites in the perovskite lattice. In the present study, the effect of low amount of donor doping on the microstructural and electrical properties of BaTiO3 based ceramics was investigated. Instead of applying lower sintering temperatures and/or compaction pressures, using low amounts of additives, BaTiO3-based ceramics were fabricated with sufficient mechanical stability to fit long-term room temperature humidity environment applications. On the other hand, low amount of additives provided the porosity percentages, required for humidity sensing process, which is mainly a surface reaction including the adsorption of water vapour to the ceramic surface. In the present study, the effects of graphite and PMMA (Polymethyl metacrylate) additions on the porosity characteristics of La+3 doped BaTiO3 based ceramics were observed. Porosity and microstructural studies were carried out for PFA containing samples. The effects of the type and PFA content on the porosity and microstructural features of BaTiO3 based ceramics were examined. It was observed that there were not any secondary phases due to the existance of PFAs and donor dopant. PMMA additions caused a more pronounced effect in porosity percent and pore size values than graphite. Donor doping and variable graphite addition concerning BT, BTL and BTLC compositions, did not change the overall microstructural features and grain morphology was similar to BT compositions. However, graphite addition enhanced grain growth due to exothermic reactions. On the other hand, PMMA caused grain refinement. Besides, organic based additive affected the grain morphology and microstructural features. Grain morphology became more homogeneous, regular and globular due to PMMA addition. This result is of great importance from the view that porous ceramics with low density could be manufactured easily by organic addition. SEM images showed that spaces between the pores and intergranular pore morphology was present. Since intergranular pores were connected by larger pores, pore network can be regarded as interconnected spaces forming a type of capillary tube. One of the main advantage of employing additives with low percentages is that it provides economical benefit for the porous ceramics. Stable microstructures related to high temperature processes were obtained by organic addition and porosity requirements were satisfied with homogeneous distribution of high porosity percentages throughout the microstructures of the porous ceramics. The effects of the type of PFA on the porosity and microstructure of BaTiO3 ceramics were examined. It was observed that there is no evolution of a secondary phase due to the existance of PFAs and La+3 dopant. PMMA additions caused a more pronounced effect in porosity and pore size than graphite addition. It was concluded that based on electrical conductivity results, porous BaTiO3 ceramics are effective candidate materials for humidity sensing applications.  Keywords: BaTiO3, sensor, porosity, graphite, PMMA

Post travmatic stress disorder and related factors of combat veterans in Turkey: A systematic review

Bu çalışma Türkiye'de silahlı çatışmaya katılmış ve çatışma sırasında yaralanmış travma sonrası stres bozukluğu (TSSB) tanılı askerlere dair yayınlanmış araştırmaların gözden geçirilmesi ve araştırmalardan elde edilen verilerin sistematik biçimde incelenmesiyle gerçekleştirilmiştir. Konuya ilişkin elli dört adet araştırmaya ulaşılmıştır ve dahil edilme kriterlerine uygun bulunan yirmibeş adet araştırma tez çalışması kapsamında değerlendirilmiştir. Tez çalışması kapsamına alınan araştırmalarda kullanılan yöntemler ve bulunan sonuçlar sistematik biçimde incelenmiştir. Bu sistematik derleme çalışması sonunda incelenen araştırmalarda silahlı çatışmada yaralanma sonucu TSSB gelişiminin askerlerde önemli bir sorun olduğu, bazı araştırmalarda gazilerin eş tanılar aldıkları, psikolojik travmayla başa çıkmak amacıyla alkol kullanımına başvurdukları, çatışma tecrübesi sonunda yakın sosyal çevresine saldırganlıkta artışlar gözlendiği sonuçlarına yer verildiği görülmüştür. Tez çalışmasında sosyal destek algısı, başa çıkma yöntemleri ve psikolojik yardım arama tutumlarını sorgulayan araştırmaların sonuçları da incelenerek veriler derlenmiştir. Silahlı çatışmayı izleyen süreçte gazilerin sosyal destek algısının pozitif hale gelmesinde sırasıyla aile, silah arkadaşları ve kurumsal desteklerin en fazla rol oynadığı incelenen araştırmalarda ortaya konan önemli sonuçlardır. TSSB tanılı askerlerin sıkça başvurdukları başa çıkma yöntemlerinden birinin dini inanç odaklı başa çıkma olduğu ve yaralanmayı vatan savunması kavramıyla özdeşleştirmenin de gazilerde başa çıkmayı kolaylaştırdığı da incelenen araştırmalarda ortaya konmuş dikkat çekici sonuçlardır. Ayrıca, gazilerin psikolojik yardım arama tutumlarının olumsuz olduğu da incelenen araştırmalarda yer verilen bir sonuç olup bu sonucun önceki gazi araştırmalarıyla uyumlu olduğu sonucuna varılmıştır. Sonuç olarak TSSB'ye ilişkin araştırmaların sistematik olarak incelenmesi bu konunun önemini ortaya koymuştur.This study was held by systematic reviewing of the researches on the soldiers who had taken part in a combat, then had been diagnosed by post-traumatic stress disorder (PTSD) in Turkey and systematically analysing data obtained from the researches. A total of fifty four published researches on the topic were reached and twenty five of them were evaluated according to inclusion criteria. The research methods utilized and the obtained data from these researches were reviewed. As a result of this systematic review study, it was found out that these researches stressed the importance of PTSD development of Turkish combat-injured soldiers, findings from some of the reviewed researches revealed that some veterans had comorbid diagnoses after physical injury, others reported that alcohol misuse by the veterans was observed for coping with the psychological trauma, some related researches indicated an association between PTSD and aggressive behaviours in close social relationships after combat experience. The results of the researches addressing the perceived social support, coping skills and seeking psychological help attitudes of the soldier were also reviewed. An important result obtained from the reviewing of the relevant researches is that following the combat experience the family, their fellow soldiers and the institutions contributed the most to the veterans' perception of the social support, respectively. According to the results of the reviewed researches, a commonly adopted coping strategy of the soldiers with PTSD was using the religious beliefs and that the soldiers might refer to their physical injury as a homeland defense for coping strategy. In addition, some researches pointed out that the negative attitudes of combat veterans towards the psychological help seeking were consistent with the results of previous veteran studies in Turkey. Consequently, the systematic review of the related researches has produced evidence on the importance of this problem

Investigation of Ferrimagnetic Sr-hexaferrite Nanocrystals for Clinical Hyperthermia

Sr-hexaferrite samples were produced via the conventional ceramic method. X-ray diffractometry (XRD) patterns confirmed the single nanocrystal phase as Sr-hexaferrite where any pattern peaks of unreacted Fe2O3 phase were  not detected. The mean crystallite size values were determined to be 44.12±3.4nm and 41.2±3.2nm for SHF-O1 and SHF-O2, respectively. The chemical bonding peaks of our sample indicated that the structure of Sr-hexaferrite formation was confirmed by FTIR spectra result. Scanning electron microscopy (SEM) images indicated clearly observed porosity regions with relative densities as high as 94% and 87% for SHF-O1 and SHF-O2 samples.The vibrating sample magnetometry (VSM) of each sample at 2K and under a magnetic field of 10 kOe yielded saturation magnetizations, Ms of 93.5 and 94.1 emu/g; remanence values, Mr of 76.4 and  67.8 emu/g for SHF-O1 and SHF-O2, respectively. The magnetization loops of both samples indicated a soft ferrimagnetic behaviour in which the saturation magnetizations were higher than those measured  at room temperature in the previous studies. The coercivities, Hc were measured to be 150Oe for both samples. The squareness values, SQR (Mr/Ms) were measured to be high, approximately 0.82 and 0.72 for SHF-O1 and SHF-O2, respectively. Depending on the adequate values of magnetization and coercivity along with small mean crystallite size and low porosity values of the obtained Sr-hexaferrite samples, we estimate that these samples are likely to be evaluated further for the potential use as thermoseeds in the field of clinical hyperthermia

Exposure of Zebrafish (Danio rerio) to Titanium Dioxide Nanoparticle Causes Paraptosis: Evaluation of Ovarian Follicle Ultrastructure

Titanium dioxide (TiO2) is widely used nanoparticle all over the world. In this study, we have investigated the histopathological effect on zebrafish ovaries after exposure to TiO2 nanoparticles. Adult zebrafish individuals were exposed to 1, 2 and 4 mg/L TiO2 for 5 days, and then their ovaries were evaluated using light and transmission electron microscopy. Numerous degenerated follicles with cytoplasmic vacuolization, mitotic catastrophe in mitochondria, chromatin condensation, mitochondrial vesiculation and dispersion at ooplasm were observed. In mitochondria, mitotic catastrophe, vesiculation, swelling and loss of organization of cristae were detected. Here we showed that TiO2 exposure trigger paraptotic type cell death in zebrafish ovary

Evaluation of drug use attitudes of patient and Its relatives attending to Çukurova University Medical Faculty Balcalı Hospital

Amaç: Akılcı olmayan ilaç kullanımı, tüm ülkelerin önemli sağlık sorunlarındandır. Ülkemizde de akılcı olmayan ilaç tüketimi alışkanlıkları ciddi bir sorun olup ilaç harcamalarının genel sağlık harcamaları içerisindeki payını artırmaktadır. Çalışmamızın amacı, Çukurova Üniversitesi Balcalı Hastanesi’ne başvuran hasta ve hasta yakınlarının ilaç kullanım alışkanlıklarının değerlendirilmesidir. Gereç ve Yöntem: Ç.Ü. Tıp Fakültesi Balcalı Hastanesi polikliniklerine başvuran 209 hasta ve hasta yakınına yüz yüze anket yöntemi ile “Akılcı İlaç Kullanım Anketi” uygulanmıştır. Bulgular: Çalışmaya katılan 209 kişinin 124’ü (% 58,4) kadındır. Kadınların yaş ortalaması 41,39±13,76, erkeklerin yaş ortalaması 44,67±13,55’dir. Çalışmaya katılanların % 34,4’ü ilkokul, % 18,7’si ortaokul, % 26,3’ü lise ve % 20,6’sı üniversite mezunudur ve % 11,0’inin sosyal güvencesi yoktur. Katılanların % 5,7’si akut bir hastalığa, % 54,6’sı kronik bir hastalığa sahipken % 39,7’sinin ise önemli bir sağlık sorunu yoktur. Katılımcıların % 53,1’i doktora danışmadan asla ilaç kullanmadıklarını belirtirken, % 11,0’ı çok nadiren, % 30,6’sı nadiren ve % 5,3’ü sıklıkla doktora danışmadan ilaç kullandıklarını belirtmişlerdir. Katılımcıların % 14,8’i akraba, arkadaş, komşu tavsiyesiyle ilaç kullandıklarını belirtmişler, % 17,2’si akraba, arkadaş, komşularına ilaç tavsiye ettiklerini belirtmişlerdir. Katılımcıların % 16,7’si sıklıkla, % 77,6’sı bazen grip-soğuk algınlığı durumlarında doktora sormadan antibiyotik kullandıklarını söylemişlerdir. Katılımcıların % 40,2’si bitkisel tedaviye başvurmadıklarını bildirirken, % 2,4’ü kanser, % 2,4’ü mide hastalıkları ve % 55,0’ı soğuk algınlığı-grip gibi durumlarda bitkisel tedaviye başvurduklarını bildirmişlerdir. Evde bulunsun düşüncesi ile antibiyotik yazdıranların oranı % 1,0, soğuk algınlığı ilaçları yazdıranların oranı % 7,2, ağrı kesici yazdıranların oranı % 23,4’tür. Sonuç: Balcalı Hastanesi’ne gelen insanların akılcı ilaç kullanım bilgisinin görece yeterli olduğu, bu durumun cinsiyete, eğitim düzeyine ve sosyal güvence düzeyine göre farklılık gösterdiği belirlenmiştir.Objective: Irrational drug usage is one of the important public health problems in all countries. Also in our country irrational drug usage patterns is a serious problem and it increases the drug's share of public health care costs. The aim of our study was evaluate the drug use patterns of patients and relatives of patients in Çukurova University Medical Faculty Balcalı Hospital. Material and Methods: Face-to-face interviews (using a questionnaire about Rational Drug Use Survey) with 209 patients and patients relatives, admitted to Çukurova University Medical Faculty Balcalı Hospital clinics. Results: 209 people participated in this study and 58 % (124) of these are women. The mean age of women was 41,39±13,76 and the mean age of the man was 44,67±13,55. If we decompose the participants to their educational attainment; primary school (34,4 %), secondary school (18,7 %), high school (26,3 %) and university (20,6 %). 11,0 % of the participants have no social security. 5,7 % of the participants have acute disease, 54,5 % of them have chronic disease and 39,7 % of them have no medical problems. 53,1 % of the participants said that they do not use drugs without consulting a medical doctor, 11,0 % of the participants said that they sometimes use drugs, 30,6 % of the participants said that they rarely use drugs and 5,3 % of the participants said that they often use drugs without consulting a medical doctor. 14,8 % of the participants said that they use drugs with advise of their relatives, friends and neighbors, 17,2 % of the participants said that they advise the drugs to their relatives, friends and neighbors when they were sick. 16,7 % of the participants said that they often use antibiotics and 77,5 % of the participants said that they sometimes use antibiotics without consulting a doctor when they had common cold or flu. 40,2 % of the participants said that they do not use herbal medicine in treatment. Patients with canser 2,4 %, patients with gastric 2,4 %, patients with common cold 55 % said that they use herbal medicine in treatment. The rate of the people, who buy drugs before they become sick, is 1,0 % for antibiotics, 7,2 % for flu drugs, 23,4 % for painkiller drugs. Conclusion: Information of rational drug usage pattern is sufficient for the patients who visit Balcalı Hospital and this condition is related to their gender, educational level and social security level

Developmental Toxicity of (4S)-2-(4-hydroxy-3-methoxyphenyl)thiazolidine-4-carboxylic acid in Zebrafish (Danio rerio)

(4S)-2-(4-hydroxy-3-methoxyphenyl)thiazolidine-4-carboxylic acid is new synthesized substance obtained from cysteine and valine. Thiazolidine derivates have important biological responses so scientists work intensively on these compounds in recent years. It is obvious that thiazolidine contained compounds will be used in future in the pharmaceutical industry to treat important diseases. Median lethal concentrations (LC50) for 48 h and 96 h were found as 1.106 +/- 0.052 mM and 0.804 mM +/- 0.102 respectively. According to LC50, exposure doses were determined as control, 0.4 mM, 0.2 mM and 0.1 mM (4S)-2-(4-hydroxy-3-methoxyphenyl)thiazolidine-4-carboxylic acid. Developmental toxicity and apoptotic features on zebrafish development were evaluated in this study. The results of this study indicate that (4S)-2-(4-hydroxy-3-methoxyphenyl)thiazolidine-4-carboxylic acid exposure cause developmental defects like pericardial edema, bent spine, tail malformation, blood accumulation, yolk sac edema but on the other hand concentration-dependent decrease in apoptotic rate. Likewise, concentration-dependent decrease in hatching and increase in mortality of embryos were also detected

Developmental Toxicity of (4S)-2-(4-hydroxy-3-methoxyphenyl)thiazolidine-4-carboxylic acid in Zebrafish (Danio rerio)

(4S)-2-(4-hydroxy-3-methoxyphenyl)thiazolidine-4-carboxylic acid is new synthesized substance obtained from cysteine and valine. Thiazolidine derivates have important biological responses so scientists work intensively on these compounds in recent years. It is obvious that thiazolidine contained compounds will be used in future in the pharmaceutical industry to treat important diseases. Median lethal concentrations (LC50) for 48 h and 96 h were found as 1.106 +/- 0.052 mM and 0.804 mM +/- 0.102 respectively. According to LC50, exposure doses were determined as control, 0.4 mM, 0.2 mM and 0.1 mM (4S)-2-(4-hydroxy-3-methoxyphenyl)thiazolidine-4-carboxylic acid. Developmental toxicity and apoptotic features on zebrafish development were evaluated in this study. The results of this study indicate that (4S)-2-(4-hydroxy-3-methoxyphenyl)thiazolidine-4-carboxylic acid exposure cause developmental defects like pericardial edema, bent spine, tail malformation, blood accumulation, yolk sac edema but on the other hand concentration-dependent decrease in apoptotic rate. Likewise, concentration-dependent decrease in hatching and increase in mortality of embryos were also detected

Label-free surface enhanced raman spectroscopy for cancer detection

Simple Summary Blood is considered a rich reservoir of biomarkers for disease diagnosis. Surface-enhanced Raman scattering (SERS) is known for its high sensitivity and has been successfully employed to differentiate blood samples from cancer patients versus healthy individuals. Different from previous reports, this study aims at investigating the reliability of the observed results by varying several parameters influencing the observed spectra. Thus, blood taken from 30 healthy individuals as the control group, 30 patients with different types of cancers, and 15 patients with various types of chronic diseases were used in the study. The results revealed that spectral differences in the cancer group was directly related to the presence of cancer-related biomarkers. Although data were obtained from only small group of patients, the recorded sensitivity and specificity values clearly show the power of the technique to detect cancer. Blood is a vital reservoir housing numerous disease-related metabolites and cellular components. Thus, it is also of interest for cancer diagnosis. Surface-enhanced Raman spectroscopy (SERS) is widely used for molecular detection due to its very high sensitivity and multiplexing properties. Its real potential for cancer diagnosis is not yet clear. In this study, using silver nanoparticles (AgNPs) as substrates, a number of experimental parameters and scenarios were tested to disclose the potential for this technique for cancer diagnosis. The discrimination of serum samples from cancer patients, healthy individuals and patients with chronic diseases was successfully demonstrated with over 90% diagnostic accuracies. Moreover, the SERS spectra of the blood serum samples obtained from cancer patients before and after tumor removal were compared. It was found that the spectral pattern for serum from cancer patients evolved into the spectral pattern observed with serum from healthy individuals after the removal of tumors. The data strongly suggests that the technique has a tremendous potential for cancer detection and screening bringing the possibility of early detection onto the table