Soft Electronics on Asymmetrical Porous Conducting Membranes by Molecular Layer-by-Layer Assembly

( Busra ),김현,심봉섭 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0

Achieving biological softness and flexibility has been a critical challenge for bioelectronic materials used in implantable bionic interfaces and wearable devices. We developed electrically conductive and biodegradable polycaprolactone membranes coated with ultrathin single-walled carbon nanotube via layer-by-layer assembly technique. The resulting membranes have hierarchically structured 3D network of conductive paths around asymmetric nano/micropores which provide softness, stretchability and anisotropic electrical conductivity. The strain sensors embedded on the membrane also demonstrate bending directional sensitivity and piezoresistivity with tunable Gauge Factor in the ranges of 5-13 with stretchability up to 100%. Furthermore, biocompatibility was confirmed by in vitro PC12 cell culture. Therefore, this implantable multifunctional membrane has considerable potential as a conductive biomaterial for bioengineered devices such as mechano-sensitive artificial interface.

Controlled release of doxorubicin from polyethylene glycol functionalized melanin nanoparticles for breast cancer therapy

( Busra Ozlu ),심봉섭 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1

In this study, polyethylene glycol (PEG) modified melanin nanoparticles (MNPs) were prepared (PEG-MNPs). A model chemotherapy drug, doxorubicin (DOX), was loaded into the PEG-MNPs with different concentrations. TEM images showed that DOX-PEG-MNPs are spherical- shaped and 15±2.2 nm in diameter. FTIR spectroscopy analysis demonstrated that MNPs were successfully modified with PEG. The release behavior of DOX from MNPs was found to be primarily diffusion controlled. In vitro cytotoxicity assays demonstrated that DOX-PEG-MNP was able to inhibit the proliferation of human breast cancer cells. The results confirm that MNPs could be used as a nanocarrier for controlled and prolonged release of the different cancer therapeutics.

Ultrasonographic evaluation of the masseter muscle in patients with temporomandibular joint degeneration

Busra Arikan,Numan Dedeoglu,Aydin Keskinruzgar Korean Academy of Oral and Maxillofacial Radiology 2023 Imaging Science in Dentistry Vol.53 No.-

Purpose: Sonographic elastography can be used to evaluate the hardness of muscle tissue through the application of compression. Strain elastography gauges hardness through the comparison of echo sets before and after compression. This study utilized ultrasonography to measure the thickness and hardness of the masseter muscle in individuals with temporomandibular joint(TMJ) osteoarthritis. Materials and Methods: This study included 40 patients who presented with joint pain and were diagnosed with TMJ osteoarthritis via diagnostic cone-beam computed tomography, along with 40 healthy individuals. The thickness and hardness of each individual's masseter muscle were evaluated both at rest and at maximum bite using ultrasonography. The Mann-Whitney U test and the chi-square test were employed for statistical analysis, with the significance level set at P<0.05. Results: The mean thickness of the resting masseter muscle was 0.91 cm in patients with osteoarthritis, versus 1.00 cm in healthy individuals. The mean thickness of the masseter muscle at maximum bite was 1.28 cm in osteoarthritis patients and 1.36 cm in healthy individuals. The mean masseter elasticity index ratio at maximum bite was 4.51 in patients with osteoarthritis and 3.16 in healthy controls. Significant differences were observed between patients with osteoarthritis and healthy controls in both the masseter muscle thickness and the masseter elasticity index ratio, at rest and at maximum bite (P<0.05). Conclusion: The thickness of the masseter muscle in patients with TMJ osteoarthritis was less than that in healthy controls. Additionally, the hardness of the masseter muscle was greater in patients with TMJ osteoarthritis.

The effect of graded motor imagery training on pain, functional performance, motor imagery skills, and kinesiophobia after total knee arthroplasty: randomized controlled trial

Busra Candiri,Burcu Talu,Emre Guner,Metehan Ozen 대한통증학회 2023 The Korean Journal of Pain Vol.36 No.3

Background: The aim was to investigate the effect of graded motor imagery (GMI) added to rehabilitation on pain, functional performance, motor imagery ability, and kinesiophobia in individuals with total knee arthroplasty (TKA). Methods: Individuals scheduled for unilateral TKA were randomized to one of two groups: control (traditional rehabilitation, n = 9) and GMI (traditional rehabilitation + GMI, n = 9) groups. The primary outcome measures were the visual analogue scale and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Secondary outcome measures were knee range of motion, muscle strength, the timed up and go test, mental chronometer, Movement Imagery Questionnaire-3, lateralization performance, Central Sensitization Inventory, Pain Catastrophizing Scale, and Tampa Kinesiophobia Scale. Evaluations were made before and 6 weeks after surgery. Results: Activity and resting pain were significantly reduced in the GMI group compared to the control group (P < 0.001 and P = 0.004, respectively). Movement Imagery Questionnaire-3 scores and accuracy of lateralization performance also showed significant improvement (P = 0.037 and P = 0.015, respectively). The Pain Catastrophizing Scale and Tampa Kinesiophobia Scale scores were also significantly decreased in the GMI group compared to the control group (P = 0.039 and P = 0.009, respectively). However, GMI did not differ significantly in WOMAC scores, range of motion, muscle strength, timed up and go test and Central Sensitization Inventory scores compared to the control group (P > 0.05). Conclusions: GMI improved pain, motor imagery ability, pain catastrophizing, and kinesiophobia in the acute period after TKA.

Numerical studies on axially loaded doubler plate reinforced elliptical hollow section T-joints

Busra Sari,Emre Ozyurt 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.43 No.1

This paper presents results of numerical studies completed on unreinforced and doubler plate reinforced Elliptical Hollow Section (EHS) T-joints subjected to axial compressive loading on the brace member. Non-linear finite element (FE) models were developed using the finite element code, ABAQUS. Available test data in literature was used to validate the FE models. Subsequently, a parametric study was carried out to investigate the effects of various geometrical parameters of main members and reinforcement plates on the ultimate capacity of reinforced EHS T-joints. The parametric study found that the reinforcing plate significantly increases the ultimate capacity of EHS T-joints up to twice the capacity of the corresponding unreinforced joint. The thickness and length of the reinforcing plate have a positive effect on the ultimate capacity of Type 1 joints. This study, however, found that the capacity of Type 1 orientation is not dependent on the brace-to-chord diameter ratio. As for type 2 orientations, the thickness and length of the reinforcement have a minimal effect on the ultimate capacity. A new design method is introduced to predict the capacity of the reinforced EHS T-joints Type 1 and 2 based on the multiple linear regression analyses.

Association between Sarcopenia and Cognitive Functions in Older Individuals: A Cross-Sectional Study

Busra Yigit,Can Oner,Huseyin Cetin,Engin Ersin Simsek 대한노인병학회 2022 Annals of geriatric medicine and research Vol.26 No.2

Background: Sarcopenia and cognitive disorders are frequently observed in older individuals. This study investigated the relationship between sarcopenia and cognitive function in this population. Methods: This cross-sectional study included 201 participants aged >65 years in Istanbul between July 1, 2020 and January 31, 2021. We screened all participants using the SARC-F (strength, assistance with walking, rising from a chair, climbing stairs, and falls) questionnaire to determine the risk of sarcopenia. Handgrip strength and skeletal muscle mass of participants at risk were measured to diagnose sarcopenia. Sarcopenia severity was evaluated using a 4-m walking speed test. We evaluated the cognitive status of participants using the Standardized Mini-Mental Test (SMMT) and the Standardized Mini-Mental Test for the Untrained (SMMT-E). Results: It was found that 10.9% (n=22) of participants was risky for sarcopenia and 6.0% (n=12) and 33.3% (n=4) had definite and severe sarcopenia, respectively. Examination of the association between cognitive impairment and SARC-F showed that 8.6% (n=14) of participants with normal cognitive function were at risk of sarcopenia compared to 20.5% (n=8) of participants with cognitive impairment (p=0.045). Evaluation of the relationship between cognitive function and sarcopenia status showed that 3.7% (n=6) of participants with normal cognitive function had sarcopenia compared to 15.4% (n=6) among participants with cognitive impairment (p=0.006). Conclusion: The rate of sarcopenia was significantly higher in older individuals with cognitive than those with normal cognitive functions.

Size dependent torsional vibration of a rotationally restrained circular FG nanorod via strain gradient nonlocal elasticity

Busra Uzun,Omer Civalek,M. Ozgur Yayli Techno-Press 2024 Advances in nano research Vol.16 No.2

Dynamical behaviors of one-dimensional (1D) nano-sized structures are of great importance in nanotechnology applications. Therefore, the torsional dynamic response of functionally graded nanorods which could be used to model the nano electromechanical systems or micro electromechanical systems with torsional motion about the center of twist is examined based on the theory of strain gradient nonlocal elasticity in this work. The mathematical background is constructed based on both strain gradient theory and Eringen's nonlocal elasticity theory. The equation of motions and boundary conditions of radially functionally graded nanorods are derived using Hamilton's principle and then transformed into the eigenvalue analysis by using Fourier sine series. A general coefficient matrix is obtained to assemble the Stokes' transformation. The case of a restrained functionally graded nanorod embedded in two elastic springs against torsional rotation is then deeply investigated. The effect of changing the functionally graded index, the stiffness of elastic boundary conditions, the length scale parameter and nonlocal parameter are investigated in detail.

Free vibration analysis Silicon nanowires surrounded by elastic matrix by nonlocal finite element method

Uzun, Busra,Civalek, Omer Techno-Press 2019 Advances in nano research Vol.7 No.2

Higher-order theories are very important to investigate the mechanical properties and behaviors of nanoscale structures. In this study, a free vibration behavior of SiNW resting on elastic foundation is investigated via Eringen's nonlocal elasticity theory. Silicon Nanowire (SiNW) is modeled as simply supported both ends and clamped-free Euler-Bernoulli beam. Pasternak two-parameter elastic foundation model is used as foundation. Finite element formulation is obtained nonlocal Euler-Bernoulli beam theory. First, shape function of the Euler-Bernoulli beam is gained and then Galerkin weighted residual method is applied to the governing equations to obtain the stiffness and mass matrices including the foundation parameters and small scale parameter. Frequency values of SiNW is examined according to foundation and small scale parameters and the results are given by tables and graphs. The effects of small scale parameter, boundary conditions, foundation parameters on frequencies are investigated.

Controlled release of doxorubicin from polyethylene glycol functionalized melanin nanoparticles for breast cancer therapy: Part I. Production and drug release performance of the melanin nanoparticles

Ozlu, Busra,Kabay, Gozde,Bocek, Ilyas,Yilmaz, Merve,Piskin, Ayse Kevser,Shim, Bong Sup,Mutlu, Mehmet Elsevier 2019 International Journal of Pharmaceutics Vol.570 No.-

<P><B>Abstract</B></P> <P>In this study, polyethylene glycol (PEG) conjugated melanin nanoparticles (MNPs) were prepared (PEG-MNPs). A model chemotherapy drug, doxorubicin (DOX), was loaded into the PEG-MNPs with varied concentrations (0.125, 0.250, 0.500 mg/mL). TEM images showed that, DOX-PEG-MNPs are spherical-shaped and 15 ± 2.2 nm in diameter. FTIR spectroscopy analysis demonstrated that MNPs were successfully modified with PEG. The UV–Vis spectroscopy results showed that the drug loading capacity of MNPs was 0.7 mg/ml of DOX in 2 mg/ml of PEG-MNPs. The time course data showed that, the release behavior of DOX from MNPs was primarily diffusion controlled. In vitro cytotoxicity assays demonstrated that MNP and PEG-MNP did not show any toxic effect on mouse fibroblast cells while DOX-PEG-MNP was able to inhibit the proliferation of human breast cancer cells. The results confirm that the application area of MNPs in controlled and prolonged drug release could be extended to the different types of cancer therapeutics.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

On Interpretation of Hyperbolic Angle

Aktas, Busra,Gundogan, Halit,Durmaz, Olgun Department of Mathematics 2020 Kyungpook mathematical journal Vol.60 No.2

Minkowski spaces have long been investigated with respect to certain properties and substructues such as hyperbolic curves, hyperbolic angles and hyperbolic arc length. In 2009, based on these properties, Chung et al. [3] defined the basic concepts of special relativity, and thus; they interpreted the geometry of the Minkowski spaces. Then, in 2017, E. Nesovic [6] showed the geometric meaning of pseudo angles by interpreting the angle among the unit timelike, spacelike and null vectors on the Minkowski plane. In this study, we show that hyperbolic angle depends on time, t. Moreover, using this fact, we investigate the angles between the unit timelike and spacelike vectors.