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Effect of Al Doping on Structural, Electrical, Optical and Photoluminescence Properties of Nano-Structural ZnO Thin Films

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Journal of Materials Science & Technology 2012年第4期28卷 329-335页

作者： M. Mozibur Rahman M.K.R. Khan M. Rafiqul Islam M.A. Halim M. Shahjahan M.A. Hakim dilip kumar saha Jasim Uddin Khan Department of Physics University of Rajshahi Rajshahi 6205 Bangladesh Materials Science Division Atomic Energy Centre Dhaka Bangladesh Industrial Physical Division BCSIR Dhaka Bangladesh

The nano-structural Al-doped ZnO thin films of different morphologies deposited on glass substrate were successfully fabricated at substrate temperature of 350 ℃ by an inexpensive spray pyrolysis method. The structural, electrical, optical and photoluminescence properties were investigated. X-ray diffraction study revealed the crystalline wurtzite （hexagonal） structure of the films with nano-grains. Scanning electron microscopy （SEM） micrographs indicated the formation of a large variety of nano-structures during film growth. The spectral absorption of the films occurred at the absorption edge of -410 nm. In the present study, the optical band gap energy 3.28 eV of ZnO decreased gradually to 3.05 eV for 4 mol% of AI doping. The deep level activation energy decreased and carrier concentrations increased substantially with increasing doping. Exciting with the energy 3.543 eV （A=350 nm）, a narrow and a broad characteristic photoluminescence peaks that correspond to the near band edge （NBE） and deep level emissions （DLE）, respectively emerged.

关键词： Thin film Nano-structure ZnO Surface morphology Photolumlnescence

The Impact of Heat Treatment and Surface Treatment on Thermal Conductivity of Heat Sinks Made of Aluminium Die Casting Alloys

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Journal of Harbin Institute of Technology(New Series) 2024年第4期31卷 34-41页

作者： Rajesh kumar Manickam dilip Raja Narayana Department of Mechanical Engineering Vel Tech Rangarajan Dr.Sagunthala R&D Institute of Science and TechnologyChennai 600001Tamil NaduIndia

This research contributes to understand the thermal management capabilities of Plate Fin Heat Sinks(PFHS)fabricated from *** uniqueness in this study is that the heat sinks were exposed to abrasive blasting,heat treatment,and graphene coating,and a full evaluation of the influence of the aforementioned treatments on the thermal management capacities of PFHS was *** PFHS is compared with 1)abrasive blasted and graphene coated heat sink,and 2)heat treated and graphene coated heat *** assess the thermal efficiency of the PFHS variants,a dedicated experimental set up was meticulously *** is noteworthy that a junction temperature of 60℃was assumed as the reference point for the *** results revealed that the charging cycle time which denotes the time required attaining the junction temperature,increased 1.3 times for the sample being abrasive-blasted at 0.5 MPa pressure and graphene-coated for 0.5 mm when the maximum heat input of 45 W is *** low heat input of 15 W is evaluated,the results revealed that there is no significant difference in charging cycle when compared to the untreated heat *** charging cycle time increased 2 times for the sample which is heat-treated at 450℃and graphene-coated for 0.5 mm at heat input of 15 *** finding unequivocally underscores the heightened capacity of the heat treated and graphene coated PFHS made of AlSi10Mg to withstand elevated junction temperatures.

关键词： PFHS abrasive blasting heat treatment graphene

Crystallization, Transport and Magnetic Properties of the Amorphous (Fe1–xMnx)75P15C10Alloys

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Journal of Crystallization Process and Technology 2012年第3期2卷 105-110页

作者： Md. Kamruzzaman Md. Abu Sayem Karal dilip kumar saha Feroz Alam Khan Bangladesh University of Engineering and Technology (BUET) Dhaka-1000 Bangladesh Department of Physics Begum Rokeya University Rangpur Rangpur-5400 Bangladesh Materials Science Division Atomic Energy Center Dhaka-1000 Bangladesh

The amorphous (Fe1-xMnx)75P15C10 (0 ≤ x ≥ 0.30) alloys were prepared by the standard melt spinning technique and investigated their crystallization, thermal, transport and magnetic properties. Crystallization was observed from 400℃ to 650℃ with an interval 50℃within 30 minutes annealing time by XRD. The as-cast samples were amorphous in nature. Annealing 400℃ to 450℃ samples showed the mixed bcc Fe and amorphous structures. The lattice parameter ‘a’ was varied from 2.855 to 2.859 ? but above 450℃, samples contained hexagonal, FeP and FeC structures. The lattice parameters ‘a’ and ‘c’ were varied from (5.016-5.036) ? and (13.575-13.820) ? , respectively. Average crystallite size was found to vary from 8 to 48 nm. Crystallization temperature and weight change were observed by differential thermal analysis and thermogravimetric analysis, respectively. Crystallization temperature was increased with increasing Mn content. Resistivity was increased above and bellows the Curie temperature. Real permeability remained almost constant upto around 106 Hz for of all samples after that it was decreased with increasing frequency and it was also decreased with Mn, whereas imaginary permeability was increased sharply above frequency 107 Hz. The value of saturation magnetization was found to decrease with increment Mn.

关键词： Metallic Glass Melt Spinning Technique Crystallization DTA VSM

Synthesis, Structural and Physical Properties of Cu1–xZnxFe2O4Ferrites

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Materials Sciences and Applications 2011年第11期2卷 1675-1681页

作者： Shahida Akhter Deba Prasad Paul Md. Abdul Hakim dilip kumar saha Md. Al-Mamun Alhamra Parveen 不详

Zn substituted Cu-Zn ferrites with a composition Cu1-xZnxFe2O4 have been synthesized by standard double sintering ceramic method and characterized by X-ray diffraction. The single-phase cubic spinel structure of all the samples has been confirmed from X-ray diffraction analyses. The lattice constant is found to increase linearly with the manganese content obeying Vegard’s law. This increase in lattice parameter is explained in terms of the sizes of component ions. It is well known that density plays a key role in controlling the properties of polycrystalline ferrites. The X-ray and bulk densities of the Cu-Zn ferrite is significantly decreased whereas porosity increased with increasing Zn concentration, thereby giving an impression that zinc might be helping in the densification of the materials. SEM micrographs exhibit a decrease in grain size with increasing Zn content. The real part of initial permeability, μ′ increase with increasing Zn contents upto x = 0.5 after that it decreases with higher Zn content.

关键词： Ferrites XRD Lattice Parameter Density Porosity Permeability

Effect of Sintering Temperature on Structural and Magnetic Properties of Ni0.55Zn0.45Fe2O4Ferrites

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Materials Sciences and Applications 2012年第5期3卷 326-331页

作者： Robiul Islam Md Obaidur Rahman M. Abdul Hakim dilip kumar saha Saiduzzaman Saiduzzaman Saroaut Noor Md Al-Mamun Department of Physics Khulna University of Engineering & Technology Khulna Bangladesh Materials Science Division Atomic Energy Centre Dhaka Bangladesh The Department of Physics Jahangirnagar University Dhaka Bangladesh

The effect of frequency and sintering temperature on initial permeability of Ni0.55Zn0.45Fe2O4 ferrites have been studied by using an impedance analyzer. The samples were prepared by conventional double sintering ceramic technique using oxide nanoparticles of grain size 30 - 50 nm. Single phase spinal structure has been confirmed for the prepared samples by X-ray diffraction. As the sintering temperatures increase from 1160℃ to 1300℃, the permeability gradually increases. The increase of permeability is ascribed to the increase of density and grain size. Grain size is expected to grow with the increase of sintering temperature. Ferrites with large average grain size posses higher initial permeability. The Curie temperatures determined from temperature dependence of permeability of the samples sintered at different temperatures are found to be Tc = (321 ± 1)℃ and independent of sintering temperature. At Ts = 1300℃, Tc is found to increase substantially which can be explained by the fact that Zn has evaporated from the surface layer.

关键词： Nanoparticle Sintering Temperature Curie Temperature Microstructure Grain Size

Thermal Behavior and Magnetic Properties of Nd-Fe-B Based Exchange Spring Nanocomposites Nd4-xTbxFe83.5Co5Cu0.5Nb1B6(x = 0, 0.2, 0.4, 0.6, 0.8 and 1) Melt-Spun Ribbons

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Advances in Materials Physics and Chemistry 2017年第6期7卷 223-241页

作者： Palash Chandra Karmaker Mohammad Obaidur Rahman Nguyen Huy Dan Samia Islam Liba Per Nordblad dilip kumar saha Sheikh Manjura Hoque Materials Science Division Atomic Energy CenterDhakaBangladesh Department of Physics Jahangirnagar UniversityDhakaBangladesh Institute of Materials Science Vietnam Academy of Science and TechnologyHanoiVietnam Solid State Physics Department of Engineering ScienceUppsala UniversityUppsalaSweden

Co-rich Nd-Fe-B nanocomposite ribbons with Tb substituted have been fabricated by single roller melt spinning technique of Nd4-xTbxFe83.5Co5Cu0.5Nb1B6 (x = 0, 0.2, 0.4, 0.6, 0.8 and 1) alloys in an argon (Ar) atmosphere at a circumferential speed of 40 m/s. According to the differential scanning calorimeter (DSC) traces the nanocomposite samples have been annealed at different temperatures like 675°C, 687°C, 700°C, 712°C and 725°C for 10 min. Crystallization behavior was studied by X-ray diffraction in which it was found that the XRD patterns are characterized by broad diffused pattern which demonstrate the amorphous state of materials. The ribbon samples were also characterized by vibration sample magnetometer (VSM) and Mössbauer spectroscopy at as-cast and annealed condition. Co-rich and Tb substitution has significantly enhanced the value of coercivity (Hc) and maximum energy product (BH)max. Highest value of Hc and (BH)max has been obtained as 2.36 kOe and 6.11 MGOe for the sample annealed at 700°C for 10 min with higher concentration of Tb. The M-H hysteresis loops show extremely soft natures which do not possess any area. We have found reduced remanent ratio (Mr/Ms) up to 0.49 at optimal annealing temperature 700°C. However, with the annealing of the samples in the above mentioned temperature, evolution of large coercivity was observed due to the formation of exchange couple hard and soft nanocrystal composites. We have investigated the variation of Curie temperature (Tc) with annealing temperature of the melt spun ribbon samples. Mossbauer spectroscopy was carried out to study the hyperfine parameters such as hyperfine field, hyperfine field distribution for full width half maximum (FWHM) and isomer shift of Fe species of these two phases.

关键词： Coercivity Maximum Energy Product Remanent Ratio Nanocomposite Hard and Soft Phases

Two-Stent Strategy for Bifurcation Lesions in Percutaneous Transluminal Coronary Angioplasty: Real-World Evidence

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World Journal of Cardiovascular Diseases 2024年第3期14卷 140-156页

作者： dilip kumar Amit Malviya Animesh Mishra Rabin Chakraborty Sanjeev S. Mukherjee Soumya Patra Arindam Pande Rana Rathor Roy Debopriyo Mondal Ashesh Halder Sumit Shanker Medica Superspecialty Hospital 127 Eastern Metropolitan Bypass Nitai Nagar Mukundapur Kolkata West Bengal India North Eastern Indira Gandhi Regional Institute of Health & Medical Sciences (NEIGRIHMS) Mawdiangdiang Shillong Meghalaya India

Background: Bifurcation lesions pose a high risk for adverse events after percutaneous coronary intervention (PCI). Evidence supporting the benefits of the two-stent strategy (2SS) for treating coronary bifurcation lesions in India is limited. This study aimed to evaluate the clinical outcomes of various 2SSs for percutaneous transluminal coronary angioplasty for bifurcation lesions in India. Materials and Methods: This retrospective, observational, multicentric, real-world study included 64 patients over 8 years. Data on demographics, medical history, PCI procedures, and outcomes were recorded. Descriptive statistics were computed using the SPSS software. Results: Patients (n = 64) had an average age of 65.3 ± 11.1 years, with 78.1% males. Acute coronary syndrome was reported in 18.8%, chronic stable angina in 40.6%, and unstable angina in 34.4% of participants. Two-vessel disease was observed in 98.4% of patients, and 99.4% had true bifurcation lesions. The commonly involved vessels were the left anterior descending artery (50%), left circumflex coronary artery (34.4%), and first diagonal artery (43.8%). Mean percent diameter stenosis was 87.2% ± 10.1%. The mean number of stents used was 2.00 ± 0.34. The 2SS techniques included the T and small protrusion (TAP) (39.1%), double kissing (DK) crush (18.8%), and the culotte techniques (14.1%). Procedural and angiographic success rate was 92.18%. Major adverse cardiovascular events at 1-year follow-up occurred in 7.8% of cases. Conclusion: The 2SS for bifurcation lesions showed favorable in-hospital and follow-up outcomes. Findings can serve as a resource for bifurcation angioplasty in India. Larger real-world studies with robust methodology are needed to validate these results.

关键词： Bifurcation Stenting Coronary Bifurcation Lesions Percutaneous

Stability study of fortified low-fat spreads with preservatives

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Food Quality and Safety 2022年第4期6卷 700-708页

作者： Suman Kharb dilip kumar Thompkinson Harshita kumari James L.Winkle College of Pharmacy University of CincinnatiCincinnatiOHUSA Dairy Technology Division National Dairy Research InstituteKarnalHaryanaIndia

Physicochemical variations in products are known to occur depending on storage *** study examined the effects of storage time on the physicochemical,sensory,rheological,and microbiological properties of fortified low-fat *** spreads containing potassium sorbate(PS;0.05%and 0.1%)or MicroGard 100(MG;0.5%and 1%)as preservatives and a control spread(CS)were packed in presterilized airtight polyethylene jars and their shelf lives were investigated by storage at(5±1)℃for 91 *** on the physicochemical properties,the addition of preservatives inhibited the formation of free fatty acids and thiobarbituric acid and influenced the pH and *** emulsion stability of the preserved samples was greater than that of the CS after 14 *** storage progressed,the sensory and rheological properties of the CS deteriorated continuously,whereas significantly smaller changes were observed for the samples containing 0.1%PS and 1%*** surface growth of yeasts and molds was the main cause of spoilage,particularly in the *** all the samples,the standard plate counts and the yeast and mold counts increased during *** contrast,the coliform counts were zero,indicating that the samples were manufactured and stored under hygienic *** samples containing lower levels of preservatives(0.05%PS and 0.5%MG)were acceptable for 70 d and 77 d as compared to 49 d for the ***,the addition of 0.1%PS and 1%MG extended the shelf life to 91 d.

关键词： Potassium sorbate(PS) MicroGard(MG) control spread(CS)

Detection of Fuel Adulteration Using Wave Optical with Machine Learning Algorithms

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Computer Systems Science & Engineering 2022年第4期41卷 19-33页

作者： S.dilip kumar T.V.Sivasubramonia Pillai Department of Instrumentation and Control Engineering Sri Krishna College of TechnologyCoimbatore641105TamilnaduIndia Department of Physics University College of EngineeringNagercoil629004TamilnaduIndia

Fuel is a very important factor and has considerable inﬂuence on the air quality in the environment,which is the heart of the *** increase of vehi-cles in lived-in areas results in greater emission of carbon particles in the *** fuel causes more contaminated particles to mix with breathing air and becomes the main source of dangerous *** is the mixing of foreign substances in fuel,which damages vehicles and causes more health problems in living beings such as humans,birds,aquatic life,and even water resources by emitting high levels of hydrocarbons,nitrogen oxides,and carbon *** frequent blending liquids are lubricants and kerosene in the petrol,and its adulteration is a considerable problem that adds to environ-mental *** study focuses on detecting the adulteration in petrol using sensors and machine learning algorithms.A modiﬁed evanescent wave opticalﬁber sensor with discrete wavelet transform is proposed for classiﬁcation of adult-erated data from the ***,support vector machine classiﬁer is used for accurate *** sensor isﬁrst tested with fuel and numerical data is classiﬁed based on machine learning ***,the result is eval-uated with less error and high accuracy of 99.9%,which is higher than all existing techniques.

关键词： Petrol adulteration discrete wavelet transform modiﬁed evanescent wave opticalﬁber SVM classiﬁer