Improved cycling performance of polypyrrole coated potassium trivanadate as an anode for aqueous rechargeable lithium batteries

Najeeb ur Rehman Lashari,Mingshu Zhao,Jun Wang,XINHAI HE,Irfan Ahmed,Miao Miao Liang,Songpon Tangsee,Xiaoping Song 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.108 No.-

The energy storage properties of layered metal vanadate, especially alkali metal vanadates have beenextensively studied. Metal vanadates have a more robust electrochemical output in contrast with pristinevanadium oxides. However, the detailed processes underlying the efficiency contrast of vanadates andvanadium oxides have rarely been studied. Herein a facile hydrothermal and low-temperature polymerizationmethod was introduced to synthesize KV3O8 and KV3O8@PPy nanowire bundles as anode materialfor an aqueous rechargeable Lithium batteries. The nanowires are composed of KV3O8·0.59H2O calculatedusing thermal gravimetric analysis (TGA). Successfully synthesized layered vanadium based KV3O80.59H2O (KVO) and KV3O8 0.59H2O@PPy (KVO@PPy) nanowires and investigated the source of theimproved electrochemical efficiency of PPy coated potassium vanadates compared to pristine KVO usingcrystal structure analysis and electrochemical tests. We demonstrated increase in electrochemical stabilityfor KVO@PPy caused by synergistic effect of K+ in vanadate nanowires and PPy coating. In KVO theoxygen atoms have close contact with the K ions, and the stable K+ serve as ‘‘pillars” between interlayersto shield the layered structures from collapse during the charge/discharge phase, while the PPy reducescharge transfer resistance. This research adds helps us design better electrode materials to be used as ananode material for ARLB using alkali metal vanadate.

Singing Voice Synthesis Using HMM Based TTS and MusicXML

Najeeb Ullah Khan(칸 나지브 울라),Jung-Chul Lee(이정철) 한국컴퓨터정보학회 2015 韓國컴퓨터情報學會論文誌 Vol.20 No.5

노래음 합성이란 주어진 가사와 악보를 이용하여 컴퓨터에서 노래음을 생성하는 것이다. 텍스트/음성 변환기에 널리 사용된 HMM 기반 음성합성기는 최근 노래음 합성에도 적용되고 있다. 그러나 기존의 구현방법에는 대용량의 노래음 데이터베이스 수집과 학습이 필요하여 구현에 어려움이 있다. 또한 기존의 상용 노래음 합성시스템은 피아노 롤 방식의 악보 표현방식을 사용하고 있어 일반인에게는 익숙하지 않으므로 읽기 쉬운 표준 악보형식의 사용자 인터페이스를 지원하여 노래 학습의 편의성을 향상시킬 필요가 있다. 이 문제를 해결하기 위하여 본 논문에서는 기존 낭독형 음성합성기의 HMM 모델을 이용하고 노래음에 적합한 피치값과 지속시간 제어방법을 적용하여 HMM 모델 파라미터 값을 변화시킴으로서 노래음을 생성하는 방법을 제안한다. 그리고 음표와 가사를 입력하기 위한 MusicXML 기반의 악보편집기를 전단으로, HMM 기반의 텍스트/음성 변환 합성기를 합성기 후단으로서 사용하여 노래음 합성시스템을 구현하는 방법을 제안한다. 본 논문에서 제안하는 방법을 이용하여 합성된 노래음을 평가하였으며 평가결과 활용 가능성을 확인하였다. Singing voice synthesis is the generation of a song using a computer given its lyrics and musical notes. Hidden Markov models (HMM) have been proved to be the models of choice for text to speech synthesis. HMMs have also been used for singing voice synthesis research, however, a huge database is needed for the training of HMMs for singing voice synthesis. And commercially available singing voice synthesis systems which use the piano roll music notation, needs to adopt the easy to read standard music notation which make it suitable for singing learning applications. To overcome this problem, we use a speech database for training context dependent HMMs, to be used for singing voice synthesis. Pitch and duration control methods have been devised to modify the parameters of the HMMs trained on speech, to be used as the synthesis units for the singing voice. This work describes a singing voice synthesis system which uses a MusicXML based music score editor as the front-end interface for entry of the notes and lyrics to be synthesized and a hidden Markov model based text to speech synthesis system as the back-end synthesizer. A perceptual test shows the feasibility of our proposed system.

Estimation of Concrete Strength in Early age using Wireless Maturity Method

Najeeb ullah Tareen,Junkyeong Kim,Jung Hyun Im,Se Hwan Park,Soojung Shin,Seunghee Park 대한토목학회 2018 대한토목학회 학술대회 Vol.2018 No.10

The effect of surface modifications of carbon nanotubes on the electrical properties of inkjet-printed SWNT/PEDOT–PSS composite line patterns

Najeeb, C K,Lee, Jae-Hyeok,Chang, Jingbo,Kim, Jae-Ho IOP Pub 2010 Nanotechnology Vol.21 No.38

<P>We prepared nanocomposite inks of poly(3,4-ethylenedioxythiophene)–poly(styrenesulfonate) (PEDOT–PSS) filled with single-walled carbon nanotubes (SWNTs) purified by acidic treatment, carboxylated by chemical oxidation and carboxyl-functionalized nanotubes physically modified with a natural gum, gum arabic. Inkjet printing of line patterns with a feature size of 100 µm width and lengths ranging from 1 to 5 cm was performed on glass substrates with a piezoelectric inkjet printer. The carboxyl-functionalized SWNT-based composite demonstrated a significant decrease (fourfold) of electrical resistance for the line patterns compared to that with a purified CNT-based composite due to improved dispersability of nanotubes in the polymer matrix. The use of gum arabic for the dispersion of carboxyl-functionalized nanotubes demonstrated a further drastic decrease (18-fold) of the resistance compared with a purified CNT-based composite owing to the formation of an extended continuous network within the line pattern. The inkjet-printed conductive patterns can be applied in various fields, such as flexible high speed transistors, high efficiency solar cells and transparent electrodes. </P>

Spectroscopic evaluation of individually dispersed single-walled carbon nanotubes

Najeeb, C.K.,Kim, D. Pergamon Press ; Elsevier Science Ltd 2013 Carbon Vol.52 No.-

We prepared the individually dispersed solutions of various single-walled carbon nanotubes (SWCNTs) synthesized by electric arc discharge, catalytic chemical vapor deposition, and high-pressure carbon monoxide process using the biocompatible chitosan derivative, chitosan hydroxyphenylacetamide, and evaluated their dispersion efficiencies. We propose a new spectroscopic parameter for quantitative evaluation of the individually dispersed SWCNTs and present the optimum SWCNT-to-dispersant ratio for high-quality dispersion of each SWCNT type based on the proposed parameter.

Biocompatible Individual Dispersion of Single-walled Carbon Nanotubes

Najeeb C. K.,Duckjong Kim 한국진공학회 2012 한국진공학회 학술발표회초록집 Vol.2012 No.2

Suitability of Camel Milk for Making Yogurt

Najeeb S. Al-Zoreky,Mutlag M. Al-Otaibi 한국식품과학회 2015 Food Science and Biotechnology Vol.24 No.2

Yogurt was produced using camel milk (CAM). Stabilizers (CMC, pectin, gum acacia, or alginate) were added at 0.6% to improve the texture and acceptability of CAM yogurt. The pH (4.59-4.63) and titratable acidity (0.71-0.87 %) of the CAM yogurt product were different from cow milk control yogurt. CAM yogurt contained 10.6 mg/mL of lactic acid based on HPLC. The separated whey (33.5%) of CAM yogurt with alginate was higher than for control cow milk yogurt (23.8%), indicating a weaker water holding capacity. Stabilizers did not improve the consistency and coagulum of CAM yogurt, compared with bovine milk yogurt.

Ultra fast UV-photo detector based on single-walled carbon nanotube/PEDOT-PSS composites.

Najeeb, Choolakadavil Khalid,Lee, Jae-Hyoek,Chang, Jingbo,Kang, Won-Seok,Kim, Jae-Ho American Scientific Publishers 2009 Journal of nanoscience and nanotechnology Vol.9 No.12

<P>Single-walled carbon nanotube (SWNT)/Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS), composites (SWNT/PEDOT-PSS) have been prepared using SWNTs surface modified with a natural gum, 'gum arabic' by simple mixing process. Thin films of SWNTs, PEDOT-PSS and the composites were prepared by vacuum filtration technique and were exposed to ultraviolet (UV) radiations for photoconductivity measurements. The surface resistivity of pristine SWNTs film increased from initial value of 50 omega to 92 omega and that of the polymer film decreased from 6.7 Komega to 3.1 Komega while the resistivity of the composite film decreased from 267 omega to 232 omega upon UV illumination. When the lamp was switched off, the initial resistivities of PEDOT: PSS and SWNTs films were recovered very slowly. Interestingly, on the other hand the composite films demonstrated a very fast relaxation within a few minutes. An on-off cycle ruled out the possibility of local heating effect and revealed that the switching property was originated from the fast transport of charge and heat in the composite films. This property of composite film might open up optoelectronic applications involving photoconductivity, such as photo sensors, organic light emitting diodes (OLED) and organic solar cells. Here in, we demonstrate the application of the SWNT/PEDOT-PSS composite film based device as a UV sensor.</P>

Development of a Music Score Editor based on MusicXML

이정철(Najeeb Ullah Khan),칸 나지브 울라(Jung-Chul Lee) 한국컴퓨터정보학회 2014 韓國컴퓨터情報學會論文誌 Vol.19 No.2

과거 작곡가들은 피아노, 바이올린, 기타, 플롯, 드럼과 같은 고전적 악기나 일반적인 도구들을 이용하여 작곡하였다. 그러나 디지털 기술의 발전으로 많은 소프트웨어 응용 프로그램이 개발되었으며 이제 음악가들은 개인용 컴퓨터를 이용하여 곡들을 제작할 수 있게 되었다. NIFF, SMDL, 그리고 MIDI와 같은 다양한 악보 표현 형식이 제안되었으나 MIDI 형식이 성공적으로 사용되어 왔다. 최근에는 MusicXML 형식이 컴퓨터 음악을 표현하는 사실상 표준으로 부상하였다. 본 논문에서는 MusicXML 형식의 구조에 대한 개요를 기술하고 C# 언어로 MusicXML 기반 악보 편집 소프트웨어를 구현하는 방법을 제안한다. 본 논문에서 제안하는 방법을 이용하여 악보 편집 소프트웨어를를 구현함으로써 구현의 효율성을 보였으며 활용 가능성을 확인하였다. In the past composers used to make music with classical instruments such as piano, violin, guitar, flute, drums, and other well-known tools. With the advent of digital technology many software programs were developed which allow musicians to compose tunes using personal computers. Many file formats were introduced such as NIFF, SMDL and MIDI but none besides MIDI has been successful. Recently MusicXML has emerged as a de-facto standard for the computer representation of music. This paper presents a brief description of the structure of the MusicXML format and describes the development of a music score editor based on MusicXML. We implemented a MusicXML-based score editing software using C# language and a feasibility test showed the efficiency of our proposed method.

Critical analysis of various supporting mediums employed for the incapacitation of silver nanomaterial for aniline and phenolic pollutants: A review

Jawayria Najeeb,Ghazia Ahmad,Saima Nazir,Khalida Naseem,Ayesha Kanwal 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.2

An enormous number of specific case studies have been reported that deal with the removal methodologies customarily employed for the reduction of common aqua-soluble pollutants [particularly nitrophenols (NPs) and nitroaniline (NAs)]. However, reviews that not only organize the literature in some presentable form but also work as a guideline for new scholars looking to exploit the field of nanocatalysis are surprisingly non-existent. Here in, an attempt has been made to comprehensively summarize the basic issues along with an insight to specific contributions devoted to NAs and NPs removal by utilizing the nanomaterial of silver. Furthermore, keeping in mind the significance of the surface functionalization of nanomaterial in catalysis, advantages/disadvantages of several entrapment mediums generally adopted for preventing the aggregation of nanomaterial are also summarized. A generalized overview of the various commonly employed removal practices along with its comparison to the catalytic reductive technique is also presented in the study. Finally, remaining unaddressed problems associated with this field and future directions for engineering cost-efficient and effective nanocatalyst assemblies are discussed in the end.