High hopes: can molecular electronics realise its potential?

Coskun, Ali,Spruell, Jason M.,Barin, Gokhan,Dichtel, William R.,Flood, Amar H.,Botros, Youssry Y.,Stoddart, J. Fraser The Royal Society of Chemistry 2012 Chemical Society reviews Vol.41 No.14

<P>Manipulating and controlling the self-organisation of small collections of molecules, as an alternative to investigating individual molecules, has motivated researchers bent on processing and storing information in molecular electronic devices (MEDs). Although numerous ingenious examples of single-molecule devices have provided fundamental insights into their molecular electronic properties, MEDs incorporating hundreds to thousands of molecules trapped between wires in two-dimensional arrays within crossbar architectures offer a glimmer of hope for molecular memory applications. In this critical review, we focus attention on the collective behaviour of switchable mechanically interlocked molecules (MIMs)—specifically, bistable rotaxanes and catenanes—which exhibit reset lifetimes between their ON and OFF states ranging from seconds in solution to hours in crossbar devices. When these switchable MIMs are introduced into high viscosity polymer matrices, or self-assembled as monolayers onto metal surfaces, both in the form of nanoparticles and flat electrodes, or organised as tightly packed islands of hundreds and thousands of molecules sandwiched between two electrodes, the thermodynamics which characterise their switching remain approximately constant while the kinetics associated with their reset follow an intuitively predictable trend—that is, fast when they are free in solution and sluggish when they are constrained within closely packed monolayers. The importance of seamless interactions and constant feedback between the makers, the measurers and the modellers in establishing the structure-property relationships in these integrated functioning systems cannot be stressed enough as rationalising the many different factors that impact device performance becomes more and more demanding. The choice of electrodes, as well as the self-organised superstructures of the monolayers of switchable MIMs employed in the molecular switch tunnel junctions (MSTJs) associated with the crossbars of these MEDs, have a profound influence on device operation and performance. It is now clear, after much investigation, that a distinction should be drawn between two types of switching that can be elicited from MSTJs. One affords small ON/OFF ratios and is a direct consequence of the switching in bistable MIMs that leads to a relatively small remnant molecular signature—an activated chemical process. The other leads to a very much larger signature and ON/OFF ratios resulting from physical or chemical changes in the electrodes themselves. Control experiments with various compounds, including degenerate catenanes and free dumbbells, which cannot and do not switch, are crucial in establishing the authenticity of the small ON/OFF ratios and remnant molecular signatures produced by bistable MIMs. Moreover, experiments conducted on monolayers in MSTJs of molecules designed to switch and molecules designed not to switch have been probed directly by spectroscopic and other means in support of MEDs that store information through switching collections of bistable MIMs contained in arrays of MSTJs. In the quest for the next generation of MEDs, it is likely that monolayers of bistable MIMs will be replaced by robust crystalline extended structures wherein the switchable components, derived from bistable MIMs, are organised precisely in a periodic manner.</P> <P>Graphic Abstract</P><P>There is a world of difference between a molecular electronic device which switches at high (blue) rather than at low (red) bias. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2cs35053j'> </P>

Knowledge about Cervical Cancer Risk Factors and Pap Smear Testing Behavior among Female Primary Health Care Workers: A Study from South Turkey

Coskun, Savas,Can, Huseyin,Turan, Sercan Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.11

Background: Cervical cancer is one of the ten most frequent cancers in Turkey. We here examined knowledge about cervical cancer in relation to Papanicolaou (Pap) testing among female primary health care workers in Hatay, a city is located in the south of Turkey. Materials and Methods: The study was completed on 261 women healthcare workers who were or had been sexually active and who accepted to participate to the study. The participants gave verbal informed consent and thereafter questionnaires prepared by the investigators were administered by personal interview. Results: Only 30.3% (n=79) of the participants regularly had a gynecologic examination. While 87.4% (n=228) of the participants reported that they had already heard about the Pap smear test, only 45.2% (n=118) had undergone this test. It was determined that had undergone an average of $1.66{\pm}0.89$ times (1-4) within the last five years. Some 56.0% (n=117) of the participants were well informed about the Pap smear test (p<0,001) and 81.1% (n=63) of the participants who regularly had gynecological examinations (p<0,001) had this test. Conclusions: For the early diagnosis of the cervical cancer, regularly having a Pap smear test is crucial. Healthcare workers should also demonstrate sensitivity about this issue. We think that the importance of the issue should be re-highlighted by organizing in-service training for female primary healthcare workers. Studies are warranted to determine the psychosociological factors that cause individuals to not have the test.

Response of a finite beam on a tensionless Pasternak foundation under symmetric and asymmetric loading

Coskun, Irfan,Engin, Hasan,Ozmutlu, Aydin Techno-Press 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.30 No.1

The static response of a finite beam resting on a tensionless Pasternak foundation and subjected to a concentrated vertical load is assessed in this study. The concentrated vertical load may be applied at the center of the beam, or it may be offset from the center. The tensionless character of the foundation results in the creation of lift-off regions between the beam and the foundation. An analytical/ numerical solution is obtained from the governing equations of the contact and lift-off regions to determine the extent of the contact region. Although there is no nonlinear term in the equations, the problem shows a nonlinear character since the contact region is not known in advance. Due to that nonlinearity, the essentials of the problem (the coordinates of the lift-off points) are calculated numerically using the Newton-Raphson technique. The numerical results are presented in figures to illustrate the behaviours of the free-free and pinned-pinned beams under symmetric or asymmetric loading. The figures illustrate the effects of the shear foundation parameter and the symmetric and asymmetric loading options on the variation of the contact lengths and the displacement of the beam.

Dynamic contact response of a finite beam on a tensionless Pasternak foundation under symmetric and asymmetric loading

Coskun, Irfan Techno-Press 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.34 No.3

The dynamic response of a finite Bernoulli-Euler beam resting on a tensionless Pasternak foundation and subjected to a concentrated harmonic load is investigated in this study. This load may be applied at the center of the beam, or it may be offset from the center. Since the elastic foundation is assumed to be tensionless, the beam may lift off the foundation, resulting in contact and non-contact regions in the system. An analytical/numerical solution is obtained from the governing equations of the contact and non-contact regions to determine the coordinates of the lift-off points. Although there is no nonlinear term in the equations, the problem appears to be nonlinear since the contact regions are not known in advance. Due to that nonlinearity, the essentials of the problem (the coordinates of the lift-off points) are calculated numerically using the Newton-Raphson technique. The results, which represent the symmetric and asymmetric responses of the beam, are presented graphically in this work. They illustrate the effects of the forcing frequency and the beam length on the extent of the contact regions and displacements.

Free Fatty Acid Accumulation by Mesophilic Lactic Acid Bacteria in Cold-Stored Milk

Coskun, Hayri,Ondul, Eda The Microbiological Society of Korea 2004 The journal of microbiology Vol.42 No.2

This study was aimed to determine the accumulation of free fatty acid by mesophilic lactic acid bac-teria (Lactococcus lactis subsp. lactis 1471, Lactococcus lactis subsp. cremoris 1000 and Lactobacillus casei 111) in cold-stored milk. According to the results, all cold-stored milks had higher acid degree val-ues than those of fresh milk. This phenomenon showed that a slight increase occurred in the accumulation of free fatty acids as a result of spontaneous lipolysis during cold storage. All lactic acid bacteria showed good performance in production of titratable acidity, which increased during fermentation of the milk (fresh and stored milks). Moreover, as the storage time was prolonged, more free fatty acid accumulation was obtained from the fermentation of the cold-stored milk by the investigated lactic acid bacteria. The control milk, which was without lactic acid bacteria, showed no change in the accumulation of free fatty acid during fermentation. From this result, it can be suggested that longer cold-storage time can induce higher free fatty acid accumulation in milk by lactic acid bacteria.

Bias in Laboratory Medicine: The Dark Side of the Moon

Coskun Abdurrahman 대한진단검사의학회 2024 Annals of Laboratory Medicine Vol.44 No.1

Physicians increasingly use laboratory-produced information for disease diagnosis, patient monitoring, treatment planning, and evaluations of treatment effectiveness. Bias is the systematic deviation of laboratory test results from the actual value, which can cause misdiagnosis or misestimation of disease prognosis and increase healthcare costs. Properly estimating and treating bias can help to reduce laboratory errors, improve patient safety, and considerably reduce healthcare costs. A bias that is statistically and medically significant should be eliminated or corrected. In this review, the theoretical aspects of bias based on metrological, statistical, laboratory, and biological variation principles are discussed. These principles are then applied to laboratory and diagnostic medicine for practical use from clinical perspectives.

Dynamic response of a Timoshenko beam on a tensionless Pasternak foundation

Coskun, Irfan,Engin, Hasan,Tekin, Ayfer Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.37 No.5

The dynamic response of a Timoshenko beam on a tensionless Pasternak foundation is investigated by assuming that the beam is subjected to a concentrated harmonic load at its middle. This action results in the creation of lift-off regions between the beam and the foundation that effect the character of the response. Although small displacements for the beam and the foundation are assumed, the problem becomes nonlinear since the contact/lift-off regions are not known at the outset. The governing equations of the beam, which are coupled in deflection and rotation, are obtained in both the contact and lift-off regions. After removing the coupling, the essentials of the problem (the contact regions) are determined by using an analytical-numerical method. The results are presented in figures to demonstrate the effects of some parameters on the extent of the contact lengths and displacements. The results are also compared with those of Bernoulli-Euler, shear, and Rayleigh beams. It is observed that the solution is not unique; for a fixed value of the frequency parameter, more than one solution (contact length) exists. The contact length of the beam increases with the increase of the frequency and rotary-inertia parameters, whereas it decreases with increasing shear foundation parameter.

Psychiatric Co-morbidity and Efficacy of Mirtazapine Treatment in Young Subjects With Chronic or Cyclic Vomiting Syndromes: A Case Series

( Murat Coskun ),( Behiye Alyanak ) 대한소화기기능성질환·운동학회(구 대한소화관운동학회) 2011 Journal of Neurogastroenterology and Motility (JNM Vol.17 No.3

The aim of this case report was to evaluate the psychiatric co-morbidity and efficacy of mirtazapine treatment in young subjects with chronic or cyclic vomiting syndromes. This is a case series of 8 young subjects (age range of 6-16 years, 11.12 ± 3.52 years) who were referred or consulted to child psychiatry department. They were referred or consulted by pediatric gastroenterology or surgery departments for the presence of non-remitting and medically unexplained vomiting. They were investigated for co-morbid psychiatric disorders using a structured psychiatric interview. An open trial of mirtazapine was conducted for the treatment and/or prevention of vomiting. Primary outcome measure was Clinical Global Impression-Improvement scale. Subjects were diagnosed with chronic (n = 5) or cyclic (n = 3) vomiting syndromes. Duration of vomiting ranged from 6 months to 10 years (3.5 ± 3.2 years). All subjects received multiple psychiatric diagnoses with anxiety disorders being the most frequent. Maximum mirtazapine dosage was 7.5-30 mg/day (16.00 ± 6.16 mg/day). Three subjects showed complete remission and 5 subjects showed much to very much improvement in vomiting. Most frequent side effects were increased appetite, weight gain and sedation. Young subjects with chronic or cyclic vomiting may frequently suffer anxiety and/or depressive symptoms or disorders. Mirtazapine could be an effective treatment option for the treatment of vomiting and co-morbid anxiety or depressive disorders in these subjects. More systematic research are needed on this topic.

An Efficiency Analysis of Takaful Insurance Industry: A Comparative Study

Ali COSKUN,Houshang HABIBNIYA,Yavuz KECELI 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.7

Takaful, which is an Islamic insurance instrument, manages risks in business, according to Shariah (Islamic law) principles and offers risk protection and savings assets. The study analyzes the comparative efficiency of takaful insurance companies by implementing empirical research. The study also provides a comprehensive literature review on the efficiency analysis of the takaful industry. The empirical part presents a wide range of efficiency comparisons of 41 takaful insurance companies in 16 countries between 2009 and 2014. The data enveloping analysis technique is utilized using the rDEA package in the R environment to compute the efficiency score. In the study, the technical efficiency, overall technical efficiency, and pure technical efficiency are calculated and compared per year and per country. The findings of the study suggest that the overall average efficiency scores of takaful companies are considerably high. The study results also indicate that the excess in the consumption of inputs decreases while the deficit in achieved outputs has been declining in the covered period. The study suggests the managers of the takaful companies can use the target efficiency scores, which are calculated by using the DEA analysis, as an ideal reference benchmark for planning their inputs and outputs.

Value of Sentinel Lymph Node Biopsy in Breast Cancer Patients with Previous Excisional Biopsy

Gokhan Coskun,Lutfi Dogan,Niyazi Karaman,Cihangir Ozaslan,Can Atalay 한국유방암학회 2012 Journal of breast cancer Vol.15 No.1

Purpose: Sentinel lymph node biopsy (SLNB) in breast cancer patients with clinically negative axilla will ensure axillary dissection only for cases with lymph node metastasis and provide information about pathologic staging as accurate as the axillary dissection. It was shown that SLNB could be successfully performed regardless of the type of biopsy. The aim of this study was to investigate the feasibility of SLNB after excisional biopsy. Methods:One hundred patients diagnosed with excisional biopsy or guide wire-localization and operated on with SLNB between February 2007 and March 2009 were retrospectively analyzed. SLNB was performed with 10 cc of 1% methylene blue alone or both methylene blue and 1 mCi of Tc-99m nanocolloid combination. Age, tumor localization and size, length of the biopsy incision, size of the biopsy specimen, multifocality, lymphovascular invasion, tumor grade, staining with methylene blue, localization, number and metastatic status of the lymph nodes stained, and success rate with a gamma probe were evaluated. Results: Sentinel lymph node (SLN) could not be identified in 9 (16.9%) of patients in the methylene blue group (n=53). In the combination group (n=47), SLN could not be identified in one patient. Of 32 patients with negative SLNB, metastatic involvement was found to be present in 5 patients after axillary lymph node dissection (false negatives). The average numbers of SLNs found in the methylene blue group and combination group were 1.4 and 1.6, respectively. SLN detection and false negative rates in the methylene blue group were 83% and 15.7%, respectively. The rates for the combination group were 98% and 6.4%, respectively. None of the parameters related to patient, tumor or process were found to affect detection rates of SLN. Conclusion: Only SLNB using a combination method is a safe and reliable technique for breast cancer patients diagnosed with excisional biopsy.