The preparation and applications of novel phosphazene crosslinked thermo and pH responsive hydrogels

Hava Ozay,Ozdem Sahin,Omer Kaan Koc,Ozgur Ozay 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.43 No.-

In this study, we synthesized a novel phosphazene compound hexakis[4-(acrylamido)phenoxy]cyclotriphosphazene (HAAP) as crosslinker. The structure of compound was identified usingspectroscopic techniques. Then, HAAP was used as crosslinker for the synthesis of thermo and pHresponsive p(NIPAM-co-VI) hydrogels. The structure and swelling behavior of hydrogel was investigated. Then, HAAP-crosslinked p(NIPAM-co-VI) hydrogels were used for in vitro release of Rhodamine 6G asdrug release matrix. Additionally, HAAP-crosslinked p(NIPAM-co-VI) hydrogels were used as supportmaterial for the preparation of cobalt metal catalysts. The prepared HAAP-crosslinked p(NIPAM-co-VI)-Co composite catalyst was used as catalyst for the reduction reaction of 4-nitrophenol.

Maternal Identity Development Education on Maternity Role Attainment and My Baby Perception of Primiparas

Hava Özkan,Sevinç Polat 한국간호과학회 2011 Asian Nursing Research Vol.5 No.2

Perpose There are no interventional study results directed at maternal identity development education,including all stages of maternity role attainment, for expectant mothers with healthy babies. This research was conducted to assess the effect of maternal identity development education on the maternity role attainment and my baby perception of primigravidas. Methods The research was carried out by using pretest-posttest quasi-experimental model with control group. A total of 120 mothers and their babies participated in this study. In the collection of the data, Personal Information Form, Semantic Differentation Scale-Myself as Mother and My Baby and the Pharis Self-Confidence Scale were used. Results It was detected that the training of identification development given for the mothers increased score averages taken from the scales of Myself as Mother, My Baby and the Pharis Self-Confidence Scale; this increase was statistically significant. There was a significant positive correlation between the Pharis Self-Confidence Scale post-test score averages and scales of Myself as Mother and My Baby. Conclusions Nurses should offer maternal identity development education, support the baby perception process in the early postnatal stages, and help develop the self-confidence of the mother in order for mothers to develop successful motherhood behaviors. Maternal identity development education should be routinely offered to all expectant mothers by specialized nurses, not just to primigravidas. There is a requirement for similar studies to be conducted on broader populations related to the subject.

GIVE ME A HUMAN! THE EFFECT OF ANTHROPOMORPHISM AND GENDER ON CONSUMERS’ INTENTION TO USE A FINANCIAL ROBO-ADVISOR

Daria Plotkina,Hava Orkut,Ahu Karageyim 글로벌지식마케팅경영학회 2023 Global Marketing Conference Vol.2023 No.07

Robo-advisors are gaining momentum, as they aim to provide personalized and low-cost financial advice (Jung et al., 2019). However, the effectiveness of robo-advisory is bounded by the lack of trust (Jung et al. 2018). Anthropomorphism or robo-advisor resemblance to a human (i.e., avatar, name, or gender) can remedy that. Indeed, robo-humanization can establish trust and impact on behavioral intents toward the advisory technology through social presence (Go & Sundar, 2019), warmth (Cyr et al., 2009), perceived expertise of the advisor (Qui & Benbasat, 2009), including perceived integrity and persuasiveness (Tan & Liew, 2020). Gender can amplify anthropomorphic cues and, thus, increase trust (Beldad et al., 2016). Finally, trust toward the technology is directly related to its adoption intent (Bruckes et al., 2019).

Classification of Grid Connected Transformerless PV Inverters with a Focus on the Leakage Current Characteristics and Extension of Topology Families

Ozkan, Ziya,Hava, Ahmet M. The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.1

Grid-connected transformerless photovoltaic (PV) inverters (TPVIs) are increasingly dominating the market due to their higher efficiency, lower cost, lighter weight, and reduced size when compared to their transformer based counterparts. However, due to the lack of galvanic isolation in the low voltage grid interconnections of these inverters, the PV systems become vulnerable to leakage currents flowing through the grounded star point of the distribution transformer, the earth, and the distributed parasitic capacitance of the PV modules. These leakage currents are prohibitive, since they constitute an issue for safety, reliability, protection coordination, electromagnetic compatibility, and module lifetime. This paper investigates a wide range of multi-kW range power rating TPVI topologies and classifies them in terms of their leakage current attributes. This systematic classification places most topologies under a small number of classes with basic leakage current attributes. Thus, understanding and evaluating these topologies becomes an easy task. In addition, based on these observations, new topologies with reduced leakage current characteristics are proposed in this paper. Furthermore, the important efficiency and cost determining characteristics of converters are studied to allow design engineers to include cost and efficiency as deciding factors in selecting a converter topology for PV applications.

DC-Bus Ripple Current Characterization of Three-Phase 2/3L-VSIs Considering the Spectral Characteristics

Ziya Ozkan,Ahmet M. Hava 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

The selection and sizing of the dc-bus capacitor for applications utilizing three-phase PWM operated voltage source inverters (VSIs), such as grid connected photovoltaic systems and motor drives are presented based on the spectral characteristics of the dc-bus current. The characterization is provided for two and three-level VSIs (2/3L-VSIs) for popular PWM methods with modulation index (Mi) and the phase angle (φ) being variable. Based on the spectral characteristics, normalized dc-bus ripple current RMS values (Kdc) are obtained which are used to calculate thermal characteristics of the dc-bus capacitor. Similarly, the dc-bus voltage ripple characteristics are provided in a normalized manner so that they can be adapted to intended design for voltage ripple calculation. Then, considering the thermal and voltage ripple constraints, a thorough algorithm for dc-bus capacitor design is provided and illustrated through examples. The proposed approach constitutes simple and rigorous guide to design dc-bus capacitors for 2/3L-VSIs.

Output Ripple Performance Evaluation and Comparison of 2L-VSI and 3L-VSI Considering the Spectral Characteristics

Ziya Ozkan,Ahmet M. Hava 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

In this paper, two-level and three-level voltage source inverters (2/3L-VSIs) with popular pulse width modulation (PWM) methods are investigated in terms of their output (ac-side) voltage and current ripple spectral characteristics and waveform quality properties such as peak-to-peak ripple, rms ripple, and weighted total harmonic distortion. As the switching frequency and the filter size influence the output waveform quality, the inverter efficiency (loss) constraint on the switching frequency, and the size constraint on the filter are also taken into consideration. The waveform quality properties and power converter losses are characterized in normalized form for all possible VSI topology and PWM method pairs and the utilization of characterization results are illustrated through 20 kVA and 100kVA grid connected photovoltaic inverter application examples. The performance results are evaluated and comparisons provided. The performance advantage of advanced topologies and PWM methods and their matched pairs is shown. The study aids understanding the 2/3L-VSI output waveform quality attributes and establishes analytical and algorithmic design guidelines for inverter design.

Classification of Grid Connected Transformerless PV Inverters with a Focus on the Leakage Current Characteristics and Extension of Topology Families

Ziya Ozkan,Ahmet M. Hava 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.1

Grid-connected transformerless photovoltaic (PV) inverters (TPVIs) are increasingly dominating the market due to their higher efficiency, lower cost, lighter weight, and reduced size when compared to their transformer based counterparts. However, due to the lack of galvanic isolation in the low voltage grid interconnections of these inverters, the PV systems become vulnerable to leakage currents flowing through the grounded star point of the distribution transformer, the earth, and the distributed parasitic capacitance of the PV modules. These leakage currents are prohibitive, since they constitute an issue for safety, reliability, protection coordination, electromagnetic compatibility, and module lifetime. This paper investigates a wide range of multi-kW range power rating TPVI topologies and classifies them in terms of their leakage current attributes. This systematic classification places most topologies under a small number of classes with basic leakage current attributes. Thus, understanding and evaluating these topologies becomes an easy task. In addition, based on these observations, new topologies with reduced leakage current characteristics are proposed in this paper. Furthermore, the important efficiency and cost determining characteristics of converters are studied to allow design engineers to include cost and efficiency as deciding factors in selecting a converter topology for PV applications.

Autophagy is a major regulator of beta cell insulin homeostasis

Riahi, Yael,Wikstrom, Jakob D.,Bachar-Wikstrom, Etty,Polin, Nava,Zucker, Hava,Lee, Myung-Shik,Quan, Wenying,Haataja, Leena,Liu, Ming,Arvan, Peter,Cerasi, Erol,Leibowitz, Gil Springer-Verlag 2016 Diabetologia Vol.59 No.7

<P>Aims/hypothesis We studied the role of protein degradation pathways in the regulation of insulin production and secretion and hypothesised that autophagy regulates proinsulin degradation, thereby modulating beta cell function. Methods Proinsulin localisation in autophagosomes was demonstrated by confocal and electron microscopy. Autophagy was inhibited by knockdown of autophagy-related (ATG) proteins and using the H+-ATPase inhibitor bafilomycin-A1. Proinsulin and insulin content and secretion were assessed in static incubations by ELISA and RIA. Results Confocal and electron microscopy showed proinsulin localised in autophagosomes and lysosomes. Beta-Atg7(-/-) mice had proinsulin-containing sequestosome 1 (p62 [also known as SQSTM1])(+) aggregates in beta cells, indicating proinsulin is regulated by autophagy in vivo. Short-term bafilomycin-A1 treatment and ATG5/7 knockdown increased steady-state proinsulin and hormone precursor chromogranin A content. ATG5/7 knockdown also increased glucose- and non-fuel-stimulated insulin secretion. Finally, mutated forms of proinsulin that are irreparably misfolded and trapped in the endoplasmic reticulum are more resistant to degradation by autophagy. Conclusions/interpretation In the beta cell, transport-competent secretory peptide precursors, including proinsulin, are regulated by autophagy, whereas efficient clearance of transport-incompetent mutated forms of proinsulin by alternative degradative pathways may be necessary to avoid beta cell proteotoxicity. Reduction of autophagic degradation of proinsulin increases its residency in the secretory pathway, followed by enhanced secretion in response to stimuli.</P>