Chemistry Commons^™

Low Loaded Pt-Co Catalyst Surfaces Optimized By Magnetron Sputtering Sequentialdeposition Technique For Pem Fuel Cell Applications: Physical And Electrochemicalanalysis On Carbon Paper Support, Osman Öztürk, Aydin Haşi̇moğlu, Oğuz Kaan Özdemi̇r, İnci̇ Karaaslan, Ali̇ Şems Ahsen

Turkish Journal of Chemistry

A series of thin Pt-Co films with different metal ratios were deposited by using the sequential cosputtering directly on a commercial hydrophobic carbon paper substrate at room temperature and in ultra-high vacuum (UHV) conditions. Their electrocatalytic properties toward the oxygen reduction reaction were investigated in 0.5 M H2SO4 solution by means of cyclic voltammetry (CV) and linear sweep voltammetry (LSV) on rotating disc electrode (RDE). The results showed that Pt particles, deposited by dc-magnetron gun, surround the large Co-clusters deposited by rf-magnetron gun. In addition, the increase of Co content led to an increase in the electrochemical active surface area …

N Doping Of Tio2 Nanocrystal For Efficient Photodegradation Of Organic Pollutants Underultraviolet And Visible Light Irradiation, Xiaoyou Yu, Qianrui Lv

Turkish Journal of Chemistry

To decrease the band gap of TiO2 and enhance its photocatalytic performance, in this work, N-doped nanocrystalline TiO2 is synthesized successfully through a simple sol-gel synthesis process with dicyandiamide used as N source. The N-doped TiO2 photocatalysts have been characterized in detail by means of powder X-ray diffraction, Raman spectroscopy, infrared spectroscopy, UV-vis spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscope. The photocatalytic activities of N-doped TiO2 to different organic pollutants are significantly different. Using 2 × 10-5 mol/L methylene blue as the target pollutant, N-doped TiO2 can produced approximately 100% conversion within 40 min, the photocatalytic degradation ability of …

Photocatalytic Decomposition Of Textile Dyestuffs By Photosensitive Metal Oxide Catalysts, Esra Yeli̇z Altun, Zehra Tuba Şi̇şmanoğlu, Güli̇n Selda Pozan Soylu

Turkish Journal of Chemistry

Textile azo dyes are one of the pollutants in waste water that adversely affect human and environmental health. Removal of these chemicals from wastewater is important for eco-system and human health. In this study, Bi2O3 nanoflakes and ZnO were synthesized by the co-precipitation method. Adsorption and photocatalytic degradation reactions were carried out to remove dyes (Victoria blue (VB) and Malachite green (MG)) from wastewater with the photocatalysts. In order to improve the activity of catalysts, cetyltrimethylammoniumbromide (CTAB) was added as a surfactant to pure oxide structures, and Bi2O3-CTAB and ZnO-CTAB catalysts were prepared. The structural and morphological properties of these …

Chemical Composition And Biological Activities Of Essential Oils Of Two New Chemotypes Of Glebionis Cass., Hüseyi̇n Servi̇

Turkish Journal of Chemistry

This paper includes the result of the first study of the chemical composition, antioxidant, antiinflammatory, and antidiabetic activities of the essential oils of Glebionis coronaria (L.) Cass. ex Spach and Glebionis segetum (L.) Fourr. from Turkey. In the current study, nine and twenty-eight constituents were determined in the essential oils of aerial parts of G. coronaria (GCE) (92.1%) and G. segetum (GSE) (90.0%), respectively. The main components were capillin (65.9%) in GCE, capillene (53.4%) in GSE. The essential oil compositions were evaluated and compared with previous researches. In the current study, the plants are classified as chemotypes of Glebionis species. …

Application Of Graphene/Nickel Oxide Composite As A Humidity Sensor, Islam Gomaa, Medhat A. Ibrahim, Hanan Elhaes

Nanotechnology Research Centre

Molecular modeling analyses at Density functional theory DFT level was used to study the possible application of modified graphene (G) as gas sensor. A model molecules of graphene sheet was constructed then modified with nickel oxide NiO attached to graphene through covalent bonds forming G/NiO composite. DFT at B3LYP/6-31G(d,p) was utilized to investigate the physical properties of G; G/NiO; G/NiO/2H2O. Results show that interacting G/NiO composite with water molecules lowers the calculated energy of the formed structure reflecting the possibility of exposing G/NiO structure to humidity, since it forms more energetically stable composition that can be detected by a proper …

ความต้องการทางการตลาดของเทคโนโลยีเครื่องควบแน่นแบบระเหยสำหรับระบบปรับอากาศในกลุ่มตลาดใหม่, กมลวรรณ บรรจงแก้ว

Chulalongkorn University Theses and Dissertations (Chula ETD)

วัตถุประสงค์ของการวิจัยครั้งนี้ 1. ศึกษาลักษณะตลาดเครื่องปรับอากาศ แนวโน้มการตลาด และลักษณะของตลาดผลิตภัณฑ์ เครื่องควบแน่นแบบระเหยสำหรับระบบปรับอากาศ (Evaporative Condensing Unit) ที่บริษัทต้องการพัฒนา 2. ศึกษาแนวทางการพัฒนาตลาดสำหรับผลิตภัณฑ์ใหม่ในสองรูปแบบ คือ แบบติดตั้งเพิ่มเติม (Retrofitting) และแบบที่ติดตั้งสำเร็จ (Built-in) โดยเก็บข้อมูลจากการสัมภาษณ์กลุ่มตัวอย่างผู้จัดการดูแลงานโครงการภาคใต้ และผู้เชี่ยวชาญด้านการติดตั้งซ่อมบำรุงระบบเครื่องปรับอากาศ 10 คน, บุคคลทั่วไป 10 คน และเจ้าของสถานประกอบการ 4 คน ร่วมกับการเก็บข้อมูลโดยใช้แบบสอบถาม 2 ชุด ชุดแรกสำหรับผู้จัดการดูแลงานโครงการภาคใต้ และผู้เชี่ยวชาญด้านการติดตั้งซ่อมบำรุงระบบเครื่องปรับอากาศ 10 คน ชุดที่ 2 สำหรับกลุ่มตัวอย่างผู้ที่เคยซื้อ หรือกำลังตัดสินใจซื้อผลิตภัณฑ์ใหม่ 400 คน โดยใช้วิธีแจกแบบสอบถามออนไลน์ในการเก็บข้อมูล ซึ่งใช้สถิติพรรณนา และสถิติอนุมาน ในการวิเคราะห์รายงานผล ผลการวิจัยพบว่า ปัจจุบันมีการใช้เครื่องปรับอากาศที่มีเครื่องควบแน่นแบบระเหย เพียงร้อยละ 0.8 โดยผู้บริโภคส่วนใหญ่มีพฤติกรรมค้นหาข้อมูลของผลิตภัณฑ์ประเภทเดียวกันจากหลายยี่ห้อ จากผู้จัดจำหน่ายหลายแห่งก่อนการตัดสินใจซื้อ ซึ่งส่วนใหญ่สนใจจะซื้อผลิตภัณฑ์ใหม่แบบที่ติดตั้งสำเร็จ (Built-in) และแบบติดตั้งเพิ่มเติม (Retrofitting) ช่วง 6-10 ปี ข้างหน้าโดยผู้บริโภคจะยอมจ่ายเพื่อซื้อเครื่องปรับอากาศที่มีเครื่องควบแน่นแบบระเหยแบบที่ติดตั้งสำเร็จ (Built-in) ขนาด 25,000 btu/h ประเภทธรรมดา (Fix speed) ในช่วงราคา 30,252-31,421 บาท สำหรับเครื่องปรับอากาศที่มีเครื่องควบแน่นแบบระเหยแบบที่ติดตั้งสำเร็จ (Built-in) ขนาด 36,000 btu/h ประเภทธรรมดา (Fix speed) ในช่วงราคา 47,369-52,020 บาท สำหรับผู้บริโภคกลุ่มเจ้าของกิจการจะยอมจ่ายเพื่อซื้อเครื่องปรับอากาศที่มีเครื่องควบแน่นแบบระเหยแบบที่ติดตั้งสำเร็จ (Built-in) ขนาด 25,000 btu/h ประเภทธรรมดา (Fix speed) ไม่เกิน 37,828 บาท สำหรับเครื่องปรับอากาศที่มีเครื่องควบแน่นแบบระเหยแบบที่ติดตั้งสำเร็จ (Built-in) ขนาด 36,000 btu/h ประเภทธรรมดา (Fix speed) ไม่เกิน 66,587.81 …

Breakdown Of Universal Scaling For Nanometer-Sized Bubbles In Graphene, Renan Villarreal, Pin-Cheng Lin, Fahim Faraji, Nasim Hassani, Harsh Bana, Zviadi Zarkua, Maya N. Nair, Hung-Chieh Tsai, Manuel Auge, Felix Junge, Hans C. Hofsaess, Stefan De Gendt, Steven De Feyter, Steven Brems, E. Harriet Åhlgren, Erik C. Neyts, Lucian Covaci, FrançOis M. Peeters, Mehdi Neek-Amal, Lino M. C. Pereira

Advanced Science Research Center

We report the formation of nanobubbles on graphene with a radius of the order of 1 nm, using ultralow energy implantation of noble gas ions (He, Ne, Ar) into graphene grown on a Pt(111) surface. We show that the universal scaling of the aspect ratio, which has previously been established for larger bubbles, breaks down when the bubble radius approaches 1 nm, resulting in much larger aspect ratios. Moreover, we observe that the bubble stability and aspect ratio depend on the substrate onto which the graphene is grown (bubbles are stable for Pt but not for Cu) and trapped element. …

Fundamentals And Applications Of Charge Transfer Dissociation Mass Spectrometry, Zachary Joseph Sasiene

Graduate Theses, Dissertations, and Problem Reports (ETD)

The recent surge in the analysis of biomolecules has driven the need for robust, versatile, sensitive, and accurate techniques such as tandem mass spectrometry for compound structural elucidation. Many fragmentation techniques have been developed over the years, but each has their own limitations, such as the loss of post-translational modifications (PTMs), inability to fragment singly charged precursor ions or cost prohibitiveness. To help fill this gap, a novel fragmentation technique called charge transfer dissociation (CTD) has been developed to fragment stored precursor ions through radical-driven fragmentation processes using kiloelectronvolt reagent cations. CTD has shown success in the analysis of proteins, …

Enabling Technologies For Medicinal Chemistry And Synthesis: I. Cannabinoids; Ii. Illudalic Acid; Iii. Microwave Chemistry, Harvey Fulo

Graduate Theses, Dissertations, and Problem Reports (ETD)

Innovations in synthetic organic chemistry such as methodology improvements, new chemical transformations and technology development significantly impact medicinal chemistry and continue to drive the drug discovery process. Here, new cyclization strategies to the pharmaceutically underexplored 3,3-dimethylcyclopentane-fused aromatic rings are described. One approach highlighted oxidative cycloisomerization, intermolecular [2+2+2] cyclotrimerization and 5-exo-dig cyclization providing indanoylindole cannabinoids that possess high affinity for human CB₂ receptors at nanomolar concentration and good selectivity index. Another featured a [4+2]-type benzannulation reaction which enabled the 5-step synthesis of illudalic acid — compared to the current available sequences (≥16 steps) — and its equipotent and LAR-selective analogs. …

Validation Of Hplc Method For The Determination Of Chemical And Radiochemical Purity Of A 68ga-Labelled Euk-Sub-Kf-(3-Iodo-Y-) Dotaga, Ayşe Uğur, Şükrü Gökhan Elçi̇, Doğangün Yüksel

Turkish Journal of Chemistry

The prostate-specific membrane antigen (PSMA) represents an ideal biomarker for molecular imaging. Various PSMA-targeted radioligands are available for prostate cancer imaging. In this study, labeling of PSMA I&T with 68Ga, as well as validation of the radiochemical purity of the synthesis product by reverse phase radio high-performance liquid chromatography (HPLC) method are intended. Since the standard procedure for the quality control (QC) was not available, definition of chemical and radiochemical purity of 68Ga-PSMA I&T was carried out according to the Q2 (R1) ICH guideline. The standard QC tests were analyzed with Scintomics 8100 radio-HPLC system equipped with a radioactivity detector. …

In Situ Preparation Of Hetero-Polymers/Clay Nanocomposites By Cuaac Click Chemistry, Mehmet Ati̇lla Taşdelen, Çağatay Altinkök

Turkish Journal of Chemistry

A series of polymer/clay nanocomposites containing mechanistically two different polymers, poly(ethylene glycol) (PEG) and poly(epsilon caprolactone) (PCL), were prepared by simultaneous copper(I)-catalyzed alkyne-azide cycloaddition click reactions. Both clickable polymers, PEG-Alkyne and PCL-Alkyne, were simultaneously clicked on to azide-functional montmorillonite (MMT-N3) nanoclay to get corresponding PEG-PCL/MMT nanocomposites. The chemical structures of the resulting nanocomposites were verified by following azide and silicone-oxygen bands using FT-IR and characteristic bands of PEG and PCL segments using 1H-NMR spectroscopy. The combined XRD and TEM analysis confirmed that all PEG-PCL/MMT nanocomposites had partially exfoliated/ intercalated morphologies. In addition, the increase of MMT-N3 loading not only improved …

Novel Nonperipheral Octa-3-Hydroxypropylthio Substituted Metallo-Phthalocyanines: Synthesis, Characterization, And Investigation Of Their Electrochemical, Photochemical And Computational Properties, Ni̇lgün Kabay, Yasemi̇n Bayğu, Meti̇n Ak, İzzet Kara, Esra Nur Kaya, Mahmut Durmuş, Yaşar Gök

Turkish Journal of Chemistry

The current study describes the synthesis, electrochemical, computational, and photochemical properties of octa (3-hydroxypropylthio) substituted cobalt (II) (4), copper (II) (5), nickel (II) (6) and zinc(II) (7) phthalocyanine derivatives. These novel compounds were characterized by elemental analysis, 1H, 13C NMR, FT-IR, UV-Vis, and MS. The redox behaviors of these metallo-phthalocyanines were investigated by the cyclic voltammetric method. The optimized molecular structure and gauge-including atomic orbital (GIAO) 1H and 13C NMR chemical shift values of these phthalocyanines in the ground state had been calculated by using B3LYP/6-31G(d,p) basis set. The outcomes of the optimized molecular structure were given and compared with …

The Role Of Some Metal Ions In Enhancement Of Photocatalytic Activity Of Fe$_{2}$O$_{3}$-V$_{2}$O$_{5}$Binary Oxide, Eda Sinirtaş İlkme, Güli̇n Selda Pozan Soylu

Turkish Journal of Chemistry

Fe$_{2}$O$_{3}$-V$_{2}$O$_{5}$ mixed oxides were synthesized with solid-state dispersion (SSD) and coprecipitation methods. In addition, transition metal oxides such as CuO, NiO, and Co$_{3}$O$_{4}$ were successfully loaded on the synthesized catalyst (Fe$_{2}$O$_{3}$-V$_{2}$O$_{5}$) using the SSD method. The composite catalysts were inspected for their photocatalytic activities in degrading 2,4-dichlorophenol under UV light enforcement. The produced samples were analyzed using X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, diffuse reflectance spectroscopy, scanning electron microscopy, photoluminescence, and the Brunauer-Emmett- Teller method. The addition of transition metal oxides improved the photocatalytic activity of Fe$_{2}$O$_{3}$-V$_{2}$O$_{5}$5 (SSD). 1CuO wt% Fe$_{2}$O$_{3}$-V$_{2}$O$_{5}$ exhibited the highest percentage of 2,4-dichlorophenol …

Comparative Study On The Effect Of Precursors On The Morphology And Electronicproperties Of Cds Nanoparticles, Kevin I. Y. Ketchemen, Sixberth Mlowe, Linda D. Nyamen, Peter T. Ndifon, Neerish Revaprasadu

Turkish Journal of Chemistry

Cadmium dithiocarbamate and cadmium ethyl xanthate complexes were synthesized and characterized by microanalysis, Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric analyses. The complexes were employed as molecular precursors for the fabrication of CdS nanoparticles in hexadecylamine (HDA) and oleylamine (OLA) at a temperature of 250 °C. Spherical and oval shaped particles with sizes ranging from 9.93 ± 1.89 to 16.74 ± 2.78 nm were obtained in OLA while spherical, oval and rod shaped particles with sizes ranging from 9.40 ± 1.65 to 29.90 ± 5.32 nm were obtained in HDA. Optical properties of the nanoparticles showed blue shifts as compared …

Fabrication And Characterization Of Amidoxime-Functionalized Silica Decorated Withcopper: A Catalytic Assembly For Rapid Reduction Of Dyes, Ijaz Ahmed Khan, Muhammad Inaam-Ul-Hassan, Hazrat Hussain, Syed Mujtaba Shah, Tariq Yasin

Turkish Journal of Chemistry

In this study, amidoxime-functionalized silica decorated with copper (AFS-Cu) was fabricated and tested for its catalytic application. Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction were employed to characterize its structure and morphology. The application of AFS-Cu as a catalyst for the catalytic reduction of methylene blue (MB) in aqueous media using NaBH$_{4}$ as reductant was evaluated. The ability to reuse as well as the effect of catalyst dose and pH of solution on the catalytic activity was investigated. The reduction of MB followed pseudo-first-order kinetics and the rate constant (k) was 0.6224 min$^{-1}$. …

The Protective Role Of Melatonin Under Heavy Metal-Induced Stress In Melissa Officinalis L., Elvisa Hodzic, Semira Galijasevic, Milica Balaban, Sebila Rekanovic, Halid Makic, Biljana Kukavica, Dijana Mihajlovic

Turkish Journal of Chemistry

Heavy metals, due to their inability to degrade, pose a serious environmental and nutritional problem. The accumulation of essential and non-essential heavy metals in living organisms reduces normal growth and development, resulting in acute poisoning, disease and even death of organisms. Melatonin is a very important multifunctional molecule in protecting plants from oxidative stress due to its ability to directly neutralize reactive oxygen species (ROS). Also, melatonin has a chelating property, which may contribute in reducing metal-induced toxicity. In this paper, the protective role of melatonin in counteracting metal-induced free radical generation was highlighted. Using the HPLC-FLD technique melatonin was …

Evaluation Of The Surface Properties Of 4-(Decyloxy) Benzoic Acid Liquid Crystal And Its Use In Structural Isomer Separation, Bi̇rol Işik, Fati̇h Çakar, Hüsnü Cankurtaran, Özlem Cankurtaran

Turkish Journal of Chemistry

The selectivity of 4-(Decyloxy) benzoic acid (DBA) liquid crystal in surface adsorption region (303.2-328.2 K) and thermodynamic region (423.2 - 433.2 K) was investigated by inverse gas chromatography at infinite dilution (IGC-ID). The selectivity parameters of the structural isomer series named butyl acetate, butyl alcohol, and amyl alcohol series were calculated for the DBA using IGC-ID technique. Additionally, the surface properties including dispersive surface energy (γ SD), free energy (ΔGAS), enthalpy (ΔHAS), and acidity-basicity constants were calculated with net retention volumes obtained from IGC-ID experiment results. When the ΔHAS and ΔGAS are constants, DBA surface was found to be an …

Preparation Of Ethyl Levulinate From Wheat Stalk Over Zr(So4)2/Sio2, Ding-Kai Wang, Wei Zhao, Ming-Yu Cui, Tian-Tian Guo, Shui-Yuan Fu, Wei-Gang Li

Turkish Journal of Chemistry

A series of Zr(SO4)2/SiO2 solid acid catalysts with different Zr(SO4)2 loadings were prepared by water-soluble-impregnation method at room temperature. Then, the prepared catalysts were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy and energy-dispersive X-ray spectrum, X-ray diffraction, adsorption/desorption of N2, and temperature-programmed desorption of NH3. The results showed that the active component Zr(SO4)2 was successfully adhered to the mesoporous SiO2, and the acid amount of Zr(SO4)2/SiO2 increased with the increasing of the Zr(SO4)2 loadings. Finally, the wheat stalk was used as raw material and depolymerized over Zr(SO4)2/SiO2 to produce ethyl levulinate (EL). The reaction mixture was separated and …

One-Pot Green Synthesized Protein-Based Silver Nanocluster As Prooxidant Biosensor, Esi̇n Akyüz

Turkish Journal of Chemistry

In this study, silver nanoclusters as prooxidant biosensor were eco-friendly synthesized using chicken egg white protein without any chemical reducing agents for measuring copper(II)-induced prooxidant activities of catechin, epicatechin, epigallocatechin gallate, resveratrol, gallic acid, chlorogenic acid, and rutin. The prooxidant activities were evaluated via measuring the absorption at 450 nm wavelength of the Cu(I)-neocuproine chelate formed by extraction of protein-bound Cu(I) with neocuproine reagent. Accuracy was determined by evaluating recovery values of wine, grape and apple samples and the obtained values were between 97.2%-98.9%. Intraday precision and inter-day reproducibility experiments were studied with three different experiments in a day and …

Synthesis Of Imidazo-1,4-Oxazinone Derivatives And Investigation Of Reaction Mechanism, Volkan Taşdemi̇r

Turkish Journal of Chemistry

In this study, nine different C-2 aroyl imidazole derivatives were synthesized in a one pot reaction with two steps, and the reduction reactions of these derivatives with NaBH4 were carried out under mild conditions. Substitution reaction of obtained imidazo methanol derivatives with chloroacetylchloride reagent and ring reaction of substitution products were investigated. It was determined that 1,4-imidazoxazinone derivative was obtained as a result of the cyclization reaction. The intermediate products obtained during the cyclization reaction were isolated, and the path of the reaction under different conditions was discussed.

Multi-Level Analysis Of Atomic Layer Deposition Barrier Coatings On Additively Manufactured Plastics For High Vacuum Applications, Nupur Bihari

Dissertations, Master's Theses and Master's Reports

While hardware innovations in micro/nano electronics and photonics are heavily patented, the rise of the open-source movement has significantly shifted focus to the importance of obtaining low-cost, functional and easily modifiable research equipment. This thesis provides a foundation of open source development of equipment to aid in the micro/nano electronics and photonics fields.

First, the massive acceptance of the open source Arduino microcontroller has aided in the development of control systems with a wide variety of uses. Here it is used for the development of an open-source dual axis gimbal system. This system is used to characterize optoelectronic properties of …

Puerarin-Coated Gold Nanoparticles (Pue-Aunps) Synthesized Via Green Synthetic Route: A New Colorimetric Probe For The Detection Of Ciprofloxacin, Tasneem Zehra, Faiqa Ahsan, Muhammad Ali Versiani, Sana Wahid, Sajid Jahangir, Muhammad Raza Shah

Turkish Journal of Chemistry

Puerarin-coated gold nanoparticles (PUE-AuNPs) synthesized via green synthetic route, a new colorimetric sensor, efficiently detected the ciprofloxacin (CP) in tap water and cow milk samples. The PUE-AuNPs were characterized by UV-visible, FTIR, AFM, and DLS techniques and were found to be spherical with an average size of approximately 19-20 nm. FTIR spectrum confirms that functional groups such as -OH, -C=O, -CO and -C=C were responsible for the reduction of gold (III) chloride trihydrate. These functional groups acted as capping agents to form AuNPs. The PUE-AuNPs sensor was proved to be selective and sensitive for the detection of CP through colorimetric …

A Fluorescent Sensor-Based Tripodal-Bodipy For Cu (Ii) Ions: Bio-Imaging On Cells, Ahmed Nuri̇ Kurşunlu, Mustafa Özmen, Ersi̇n Güler

Turkish Journal of Chemistry

A general synthetic method was improved to synthesize a chemosensor based on a tripodal Bodipy (t-BODIPY) structure. The product and its intermediate products were successfully prepared and fully characterized. The metal ion sensing performance of the tripodal compound was evaluated by UV/Vis and fluorescence spectroscopies. According to the obtained data, t-BODIPY is a selective and sensitive fluorescence probe for detection of Cu2+ ions in the presence and in the absence of competing ions. This chemosensor presents relatively a low detection limit of 5.4 x10-7 M for Cu2+. Bio-imaging studies on living yeast cells suggest that t-BODIPY has some advantages over …

การพัฒนาหน่วยควบแน่นแบบระเหยสำหรับระบบปรับอากาศขนาดกลาง, ไปรยา ทองเหลือง

Chulalongkorn University Theses and Dissertations (Chula ETD)

หน่วยควบแน่นแบบระเหย (Evaporative condenser unit) คือการอาศัยหลักการระเหยของน้ำมาช่วยเพิ่มความสามารถในการระบายความร้อนของเครื่องปรับอากาศ งานวิจัยนี้มีจุดประสงค์เพื่อพัฒนาหน่วยควบแน่นแบบระเหยและศึกษาปัจจัยที่มีผลต่อการเพิ่มประสิทธิภาพของเครื่องปรับอากาศ ได้แก่ ความชื้นสัมพัทธ์โดยรอบ (Ambient relative humidity) และอัตราการไหลของน้ำ (Water flow rate) โดยออกแบบคอยล์เสริมเพื่อเป็นบริเวณที่ใช้ในการฉีดพ่นน้ำ พบว่าการเชื่อมต่อคอยล์เสริมบริเวณดิสชาร์จสูงกว่าบริเวณลิควิด 3.5% การทดลองเพื่อศึกษาเปลี่ยนแปลงค่าความชื้นสัมพัทธ์ควบคุมโดยปรับค่าความเร็วอากาศพบว่าเมื่อความเร็วอากาศลดลงทำให้ความชื้นสัมพัทธ์เพิ่มขึ้น และความสามารถในการระบายความร้อนมีค่าสูงสุดในช่วงความชื้นสัมพัทธ์ระหว่าง 73.1% ถึง 80.9% การทดลองศึกษาการเปลี่ยนแปลงอัตราการไหลของน้ำพบว่าพื้นที่สัมผัสบริเวณผิวคอยล์เสริมมากจะสามารถลดอุณหภูมิของสารทำความเย็นได้มากเช่นกัน นอกจากนี้ขนาดของหัวฉีดพ่นและความชื้นสัมพัทธ์ยังส่งผลต่อการลดลงของอุณหภูมิสารทำความเย็นอีกด้วย ยิ่งไปกว่านั้นในการทดลองเพื่อหาประสิทธิภาพการทำงานของต้นแบบหน่วยควบแน่นแบบระเหยพบว่าสามารถเพิ่มประสิทธิภาพจากเครื่องปรับอากาศที่ระบายความร้อนด้วยลมปกติได้สูงถึง 20.36%

Synthesis And Biological Activities Of Chalcone Derivatives, Ade Danova

Chulalongkorn University Theses and Dissertations (Chula ETD)

Chalcones have drawn attention due to the simple structures and wide spectra of biological activities. Their core structure bearing diaryl rings with α,β-unsaturated ketone was generated easily using Claisen-Schmidt condensation. In this study, one hundred and eight chalcones and their derivatives were synthesized; among them, twenty-five were disclosed as new compounds. All synthesized chalcones were well-characterized by means of spectroscopy and evaluated for their anti-cancer (A549) and anti-inflammatory activities, and α-glucosidase inhibition. For anti-cancer activity, 3',4',5'-trimethoxyphenyl on the A ring, and hydroxy and methoxy groups on the B ring exhibited high potent inhibitory activity against A549 with three best potent …

Advanced Raman Spectroscopy Detection Of Oxidative Damage In Nucleic Acid Bases: Probing Chemical Changes And Intermolecular Interactions In Guanosine At Ultralow Concentration, Francesca Ripanti, Claudia Fasolato, Flavia Mazzarda, Simonetta Palleschi, Marina Ceccarini, Chunchun Li, Margherita Bignami, Enrico Bodo, Steven E.J. Bell, Filomena Mazzei, Paolo Postorino

Bioelectrics Publications

DNA/RNA synthesis precursors are especially vulnerable to damage induced by reactive oxygen species occurring following oxidative stress. Guanosine triphosphates are the prevalent oxidized nucleotides, which can be misincorporated during replication, leading to mutations and cell death. Here, we present a novel method based on micro-Raman spectroscopy, combined with ab initio calculations, for the identification, detection, and quantification of oxidized nucleotides at low concentration. We also show that the Raman signature in the terahertz spectral range (<100 >cm(-1)) contains information on the intermolecular assembly of guanine in tetrads, which allows us to further boost the oxidative damage detection limit. Eventually, we …

Chemometrics Using R, David T. Harvey

Chemistry & Biochemistry Faculty Publications

Although you may not yet know what we mean by the term chemometrics, you almost certainly make routine use of chemometric techniques in your classes and labs: reporting an average result for several trials of an experiment or creating a calibration curve and using it to find an analyte’s concentration are two examples of chemometric methods analysis with which you almost certainly are familiar. The goal of this textbook is to provide an introduction to chemometrics suitable for the undergraduate chemistry curriculum at the junior or senior level; indeed, much of this textbook's content, including many of the examples and …

Establishing Independent Tunability Of The Mechanical And Transport Properties Of Polymer Gels, Lucas Rankin

Master’s Theses

Polymer gels can be used in the fabrication of materials for filtering liquid and gaseous media, solid-state electrolytes, and transdermal medical patches. This diverse range of applications primarily relies on the transport and mechanical properties of polymer gels. Both sets of properties have shown excellent tunability, but typically in a coupled fashion. Establishing the independent tunability of the transport and mechanical properties of polymer gels (using simple, cost-effective methods) is paramount if polymer gels are to be used to their full potential. Specifically, block copolymer gels self-assemble into organized nanoscale networks within the gel solvent, which allows for facile control …

The Effects Of Increasing Positively Charged Metal Ions Within Synovial Fluid, Kandisi Anyabwile

Williams Honors College, Honors Research Projects

Osteoarthritis is a degenerative joint disease that affects 10% of men and 13% of women over age of 60. It is the degradation of the cartilage between two bones; obesity, age, overuse, or injury are major contributors to the development of this disease. The joint is incapsulated by the synovial sac filled with a viscous solution that aids in lubrication referred to as synovial fluid. If the synovial sac is ruptured due to injury, positive ions (K⁺, Na⁺, Ca²⁺, and Fe³⁺) may affect viscoelastic properties within the sac. The purpose of this …

Proto-Rna Synthesis Using Glycerol And Phosphate Anion, Noah Parker

Williams Honors College, Honors Research Projects

Nucleic acids are important molecules for all life, serving as the primary molecules for information storage and reproduction. RNA has long been thought to be the molecule that initiated protein synthesis. However, RNA has recently been thought to be too complex to synthesize prebiotically. Through a 1:1 mole ratio condensation of glycerol and phosphoric acid, I generated glycerol-phosphate oligomers that resemble a primitive form of the carbon-phosphate backbone of RNA. 75 mmol MgCl2 was added to some samples to see if the Mg cation could stabilize the reaction intermediates and further promote longer proto-RNA oligomers. These samples were all heated …