FRICTION BRAKING PERFORMANCE OF NANOFILLED HYBRID FIBER REINFORCED PHENOLIC COMPOSITES: INFLUENCE OF NANOCLAY AND CARBON NANOTUBES

TEJ SINGH,AMAR PATNAIK,BHABANI K. SATAPATHY 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2013 NANO Vol.8 No.3

Graphite lubricated phenolic-based friction composites filled with nanoclay and Multiwalled carbon nanotubes (MWCNT) and reinforced with lapinus and Kevlar fibers have been successfully fabricated for evaluation of their physical, chemical, mechanical and tribological properties, respectively. The increase in nanoclay and MWCNT contents led to the increase in bulk physical properties such as void contents, ash contents, water absorption and compressibility. The impact, tensile and flexural strengths get affected deleteriously when complemented by lapinus and kevlar fibers in the composites. However, with the increase in nanoclay and MWCNT contents the μ-performance, friction fade resistance and friction recovery enhanced whereas, friction fluctuations, stability and variability coefficients have been observed to be dependent on the composition. The addition of nanoclay and MWCNT raises the disc temperature whereas wear resistance of the friction composites increases with the decreasing in nanoclay and MWCNT contents. Comprehensively, it is found that with the higher nanoclay: MWCNT ratio (i. e., 1.375:1.375 wt.%) overall frictional response (μp = 0.386) is enhanced, showed lowest fading (fade = 22.80%) and excellent recovery performance (recovery = 130.37%). Finally, the wear surface morphology studies have been done by using scanning electron microscope (SEM) to analyze the wear mechanisms qualitatively by understanding nature of the friction contact patches.

ODA and GAIN: The Key to Promoting Innovation

Tej Singh 이화여자대학교 생명의료법연구소 2017 Asia Pacific Journal of Health Law & Ethics Vol.10 No.2

Medicine has greatly advanced in recent decades, but has it reached its peak? With increasing costs for getting the Federal Drug Administration s ( FDA ) approval and for performing clinical trials, pharmaceutical companies and drug companies are hesitant to research and develop drugs that do not have a significant market despite protections offered through patents. For example, companies are more reluctant to research and develop drugs for rare diseases and drugs for antibiotic-resistant strains of microorganisms as there is not enough demand for such drugs, even if the drug is able to obtain a patent. Pharmaceutical drug developers rely strongly on the patent system and regulatory incentives in developing drugs. The patent system, for example, allows the drug developer to control the market for a certain period of time so that it can recover its drug development costs and get rewarded for its innovative efforts. Because drugs for rare diseases and antibiotic resistant strains of pathogens have such a small market and affect a limited number of people, pharmaceutical developers often lack incentives to research and develop such drugs. However, regulations such as the Orphan Drug Act ( ODA ) and Generating Antibiotic Incentives Now ( GAIN ) Act attempt to provide incentives to pharmaceutical developers for rare diseases, also called orphan diseases, and antibiotic resistant ailments. However, are these incentives enough? Is the current patent system still working for all pharmaceuticals? This paper seeks to address these questions and other issues concerning the pharmaceutical industry and its relationship to the patent system, specifically related to the Orphan Drug Act and Generating Antibiotic Incentives Now.

Charge transport in polythiophene:fullerene:nanotube bulk heterojunction photovoltaic devices investigated by impedance spectroscopy

Arun Tej Mallajosyula,S. Sundar Kumar Iyer,Baquer Mazhari 한국물리학회 2013 Current Applied Physics Vol.13 No.4

P3HT:PCBM bulk heterojunction devices incorporating SWNTs, which are predominantly metallic in character, have been analyzed using impedance spectroscopy to understand the effect of SWNTs on their charge carrier transport properties. SWNTs reduce the effective lifetime of injected charge carriers. Frequency dependence of capacitance and conductance of P3HT:PCBM devices show monotonic variations without any clear peak positions. Simulations of the complex admittance of the P3HT:PCBM devices under trap free space charge limited current within the framework of SchereMontrol theory are used to qualitatively show that such characteristics are a signature of charge transport which is highly dispersive in nature. The position of peak speak in the imaginary part of impedance Im(Z), which is essentially same as the first transition frequency of ColeeCole plot, has a direct relation with the effective dc mobility of charge carriers which varies with dispersion parameters. Using the dc mobility values and the voltage variation of peak frequency of Im(Z), the ratio of sdc to speak has been calculated. The magnitude of this ratio is indicative of the degree of dispersiveness in transport. It has been shown that, SWNTs at low concentrations tend to reduce the dispersiveness in charge transport.

Transition-Metal-Free Benzannulation for Diverse and Polyfunctionalized Biaryl Formation

Poudel, Tej Narayan,Lee, Yong Rok American Chemical Society 2015 ORGANIC LETTERS Vol.17 No.9

<P>A novel and efficient synthesis of highly functionalized and diverse biaryls via mild base-promoted transition-metal-free benzannulation was achieved in good yield from readily available β-ketoesters, β-ketoamides, or 1,3-diketones with cinnamaldehydes or aryl aldehydes. This transformation comprises a sequence of the formation of three new bonds through multicomponent reactions as a one-pot procedure. This novel biaryl formation proceeds through domino Michael addition/intramolecular and intermolecular aldol/[1,5]-hydrogen shift/tautomerization. This protocol provides a great advantage in introducing various functional groups on the aromatic ring of biaryls.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/orlef7/2015/orlef7.2015.17.issue-9/acs.orglett.5b00996/production/images/medium/ol-2015-00996e_0013.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ol5b00996'>ACS Electronic Supporting Info</A></P>

Base-promoted ring opening of 3-chlorooxindoles for the construction of 2-aminoarylthioates and their transformation to quinazolin-4(3<i>H</i>)-ones

Poudel, Tej Narayan,Khanal, Hari Datta,Lee, Yong Rok The Royal Society of Chemistry 2018 NEW JOURNAL OF CHEMISTRY Vol.42 No.6

<P>An unprecedented methodology for the preparation of diverse <I>S</I>-alkyl 2-aminoarylthioates has been developed based on cesium carbonate-promoted direct ring opening of 3-chlorooxindoles with thiols. This novel protocol proceeds <I>via</I> cascade sulfenylation, aerial oxidation, C2-C3 bond cleavage, and decarboxylation. The resulting products from this transformation exhibit potential for application as fluorescent sensors for the detection of Fe<SUP>3+</SUP> ions. In addition, this methodology provides a concise pathway for the construction of a variety of biologically interesting quinazolin-4(3<I>H</I>)-ones in good yields.</P>

Cu(I)-/Base-Mediated Domino [5 + 3 + 1] Annulation for Highly π-Extended Carbazole Frameworks and DFT Mechanistic Insights

Poudel, Tej Narayan,Karanjit, Sangita,Khanal, Hari Datta,Tamargo, Ramuel John Inductivo,Lee, Yong Rok American Chemical Society 2018 ORGANIC LETTERS Vol.20 No.18

<P>An efficient synthesis of highly π-extended carbazoles is described via an unexpected domino [5 + 3 + 1] annulation approach. The Cu(I)-/base-promoted reactions of 2-nitrocinnamaldehydes with benzyl cyanides provide diverse benzo[<I>b</I>]carbazoles. The reaction is proposed to proceed via a sequential Michael addition/intramolecular addition of an enol into a nitro group, 6π- electrocyclization, and the final oxidative aromatization as supported by density functional theory calculations. Some of the synthesized carbazoles showed significant potential in fluorescence sensing of Cu<SUP>2+</SUP> ions.</P> [FIG OMISSION]</BR>

Eco-friendly synthesis of diverse and valuable 2-pyridones by catalyst- and solvent-free thermal multicomponent domino reaction

Poudel, Tej Narayan,Lee, Yong Rok,Kim, Sung Hong The Royal Society of Chemistry 2015 GREEN CHEMISTRY Vol.17 No.9

<P>An efficient and highly eco-friendly synthesis of diverse and functionalized 2-pyridone derivatives in good yield <I>via</I> the thermal multicomponent reaction of 4-oxo-4<I>H</I>-chromene-3-carbaldehydes with 1,3-diketoesters and anilines or primary aliphatic amines under catalyst- and solvent-free conditions is described. This reaction proceeds <I>via</I> domino Knoevenagel condensation/Michael addition/ring opening/ring closure reactions.</P> <P>Graphic Abstract</P><P>An eco-friendly protocol for diverse and functionalized 2-pyridone derivatives <I>via</I> a multicomponent reaction under catalyst- and solvent-free conditions has been developed. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c5gc01526j'> </P>

Preparation and characterization of a novel sprayable hydrogel for skin preparation to record ECG and other biopotentials

Boppudi Sunil Tej,Belal Suliman,Guntur Sitaramanjaneya Reddy 대한의용생체공학회 2020 Biomedical Engineering Letters (BMEL) Vol.10 No.4

Wet electrodes are widely used to perform biopotential measurements from the body, such as electroencephalogram, electrocardiogram, and electromyogram. These electrodes have certain disadvantages, including bacterial growth, irritation in long-term recordings, infection to patients’ skin caused by skin preparation techniques, and unpleasant feeling caused after their removal. Thus, a sprayable hydrogel (SH) was designed to avoid these problems. Five electrode configurations, namely, Zipprep™, wet Ag/AgCl, wipes, dry Ag/AgCl, and SH, were tested using an impedance analyzer. Measurements were obtained by placing each of the electrode systems on the forearm of five subjects, which comprised one Caucasian, two Indians, one Syrian, and one Cypriot aging between 23 and 60 years for 10 min. Impedance versus time and reactance versus resistance performance plots were compared and assessed. The performance of the SH sprayed under dry electrodes had lower impedance values compared with those of the dry Ag/AgCl and wipes. As a result, the SH electrode configuration can be used as an electrode set-up for acquiring and recording various physiological signals.

Design, synthesis and biological studies of tetrazole fused imidazopyridines

Reddy Banoth,Taneja Amit Kumar,Tej Mandava Bhuvan,Navya Sri Komati,Tej Mandava Bhagya,Vijayavardhini Suryadevara,Srilaxmi Dandamudi,Tiruveedhula Somasekhar,Penumutchu Srinivasa Rao,Rao Mandava V. Basa 한국탄소학회 2024 Carbon Letters Vol.34 No.1

New tetrazole fused imidazopyridine derivatives (12a–j) were developed to exploit their cytotoxic activity towards cancer cell lines-MCF7, A549, and MDA-MB-231, utilizing MTT reduction assay with doxorubicin as standard drug. The compounds 12 h and 12j demonstrated strong anticancer activity bearing IC50 values 1.44 µM and 1.33 µM against A549 cell line.

A randomized prospective study comparing acute toxicity, compliance and objective response rate between simultaneous integrated boost and sequential intensity-modulated radiotherapy for locally advanced head and neck cancer

Akanksha Grover,Tej Prakash Soni,Nidhi Patni,Dinesh Kumar Singh,Naresh Jakhotia,Anil Kumar Gupta,Lalit Mohan Sharma,Shantanu Sharma,Ravindra Singh Gothwal 대한방사선종양학회 2021 Radiation Oncology Journal Vol.39 No.1

Purpose: Intensity-modulated radiotherapy (IMRT) provides higher dose to target volumes and limits the dose to normal tissues. IMRT may be applied using either simultaneous integrated boost (SIB-IMRT) or sequential boost (SEQ-IMRT) technique. The objectives of this study were to compare acute toxicity and objective response rates between SIB-IMRT and SEQ-IMRT in patients with locally advanced head and neck cancer. Materials and Methods: Total 110 patients with locally advanced carcinoma of oropharynx, hypopharynx, and larynx were randomized equally into the two arms (SIB-IMRT vs. SEQ-IMRT). Patients in SIB-IMRT arm received dose of 66 Gy in 30 fractions, 5 days a week, over 6 weeks. SEQ-IMRT arm’s patients received 70 Gy in 35 fractions over 7 weeks. Weekly concurrent cisplatin chemotherapy was given in both arms. Patients were assessed for acute toxicities during the treatment and for objective response at 3 months after the radiotherapy. Results: Grade 3 dysphagia was significantly more with SIB-IMRT compared to SEQ-IMRT (72% vs. 41.2%; p = 0.006) but other toxicities including mucositis, dermatitis, xerostomia, weight-loss, incidence of nasogastric tube intubation and hospitalization for supportive management were similar in both the arms. Patients in SIB-IMRT arm showed better treatment-compliance and had significantly less treatment-interruption compared to SEQ-IMRT arm (p = 0.028). Objective response rates were similar in both the arms (p = 0.783). Conclusion: Concurrent chemoradiation with SIB-IMRT for locally advanced head and neck cancer is well-tolerated and results in better treatment-compliance, similar objective response rates, comparable incidence of mucositis and higher incidence of grade 3 dysphagia compared to SEQ-IMRT.