OH Peak Research Articles

Physicochemical properties and Structural Characterization of Chitosan Synthesized from Rare Spined Murex, Murex trapa (Roding, 1798) Shell Waste

Chitosan is derived from Murex trapa as the starting source by the process deacetylation of chitin, which is carried out for 6 hours using 40% NaOH at 90ºC. The yield (17%) and physiochemical properties like ash (0.954%), moisture content (4.2%), and solubility, degree of deacetylation (73), fat binding capacity (252%), and water binding capacity (280%) were indicated the M. trapa is a substantial alternate source of chitosan. Fourier transforms infrared spectroscopy (FT-IR) analysis shows characteristic peaks of OH at 3450cm-1 and amine at 1660cm-1, X-ray diffraction (XRD) analysis indicated two vital characteristic peaks 10° and 20° at (2θ). Scanning electron microscope (SEM) was used to determine surface morphology of isolated chitosan. Also, Thermogravimetric analysis (TG/DTA) was employed to characterize the thermal stability of M. trapa chitosan. Procoagulant ability, plasma recalcification time assays and minimum bactericidal activity confirmed the hemocompatibility and antibacterial activity of the prepared chitosan. The isolated chitosan can be considered as a potent anticoagulant and antibacterial drug in future.

A study on activation of polyethylene glycol and its characterization by infrared spectroscopy and thin layer chromatography

Polyethylene Glycol (PEG) is the most popular polymeric material used for alteration and control of biodistribution. PEG may increase the lifetime of “drug carrier” assembly which helps in administering lower concentration of the “drug carrier” composite. It has been used widely for the modification of carriers used in therapeutics because PEG offers a shielding characters that avoids rapid renal clearance from the body. This study was carried out at Dolphin Institute of Biomedical and Natural Sciences, Dehradun and Indian Institute of Technology (IIT), Roorkee, India during May-July 2005. Activation of PEG of different molecular weight (400 Da, 4000 Da, 8000 Da and 20,000 Da) was done using dry benzene, Triethylamine, Ethylene dichloride and 4-nitrophenyl chloroformate. Reaction mixture was monitored on TLC using EDC: Methanol (7:3). Then reaction mixture was portioned between EDC & water. The lower fraction in separating funnel of EDC was collected & concentrated on rota evaporator to get activated PEG. From the above reaction and structure it was clear that 4-Nitrophenyl Chloroformate contains two highly electronegative groups i.e. NO2 and Cl. These two groups interact with each other resulting in neutralization of polarity. It then acts as non-polar molecule and shows high affinity for mobile phase (methanol & EDC). Therefore, 4-Nitrophenylchloroformate has the highest mobility and PEG has lowest mobility. From IR Spectroscopy it was found that the peak of Hydroxyl group- (OH) of PEG was at 3400- 3450cm-1. The peak of C-Cl bond was found at 746 cm-1. But after the reaction between PEG and 4-Nitrophenyl Chloroformate the- OH peak was found not so deep as in PEG. The peak was somewhat short and broad.

Dissolution mechanisms of water in depolymerized silicate (peridotitic) glasses based on infrared spectroscopy

The dissolution of water changes the chemical and physical properties of melts. The effect of water dissolution depends on the bulk H2O content and dissolution mechanisms. Previous research mainly focused on relatively polymerized glasses, whereas dissolution mechanisms of water in highly depolymerized glasses have not been well studied. We investigated three sets of hydrous (up to 5 wt% H2O), highly depolymerized glasses using Fourier transform infrared spectroscopy. The three suites of glasses can be classified as tephritic (non-bridging oxygens to tetrahedral cations, NBO/T ≈ 0.9), basanitic (NBO/T ≈ 1.5), and peridotitic (NBO/T ≈ 2.5). The comparison of infrared spectra indicated four prominent features. First, the combination band related to molecular H2O at ∼ 5200 cm−1 decreases in relative intensity with increasing depolymerization. At 2 wt% bulk H2O, the proportion of H2O molecules decreases from the tephritic through basanitic to peridotitic glasses, where the proportion of H2O molecules is below 10 %. At 5 wt% bulk H2O, the proportion of H2O molecules in the peridotitic glass is around 20 %, whereas it is around 50 % in the basaltic glass with the same H2O content. Second, a second peak appears at 4270–4180 cm−1, next to the (Si,Al)OH combination peak (network hydroxyl), with increasing CaO and MgO contents in basanitic (∼25 wt% CaO) and peridotitic (∼40 wt% MgO) glasses, respectively. We assign this peak to the (Mg,Ca)OH group (free hydroxyl); this is the first identification of this group based on infrared spectroscopy. This assignment is also supported by IR data on Mg(OH)2 and Ca(OH)2 crystalline phases from the literature. Third, the ratio of (Si,Al)OH and (Mg,Ca)OH peak absorbances remains nearly constant with increasing water content in basanitic and peridotitic glasses, suggesting no effect of water on polymerization of extremely depolymerized melts. Fourth, the (Si,Al)OH peak shifts to lower wavenumbers with increasing depolymerization. As a result, the (Si,Al)OH peak position could potentially be used to evaluate the degree of melt polymerization in general, and the effect of water on melt polymerization in particular.

Process analysis of asymmetric interaction between copper and atrazine in a system of macrophytes

To clarify the mutual influence and inner processes between heavy-metal and pesticide pollutants, single copper and atrazine as well as binary mixtures were spiked in a system of aquatic Acorus tatarinowi Schott. The results show that: the total copper amount in roots was 23.31 and 41.46 times as much as those in leaves in single and co-contaminated copper pollution. In the solution, the copper removal reached equilibrium in 3 days. Atrazine raised plant-mediated copper removal by 20.69 % by calculating mass balance, and the increase in pH value and organic matter and the decrease of nitrate in solutions were key factors driving it. Correlation analysis demonstrated that the pH increase was mainly caused by the decline of nitrate and increases in organic matter in the solution. Hydroxyl units on the surface of organic matter in solutions provided binding sites for Cu2+, which was demonstrated by CO and OH peak position alterations in Fourier Transform Infrared Spectrometer. In turn, the root contained 2.56 and 2.04 times as much as atrazine in leaves in single and co-contaminated atrazine treatments. In the solution, atrazine removal became stable after 7 days. Cu2+ inhibited the total accumulation of atrazine in plants by 12.5 %. Copper-induced biological phenol-like components in solution decreased the total atrazine accumulation in A. tatatinowii.

Synthesis and Characterization of Molecularly Imprinted Polymer with Oleic Acid as a Template

Molecularly Imprinted Polymer-Oleic Acid (MIPOA) and Molecularly Imprinted Polymer-Palmitic Acid (MIPPA) were synthesized using oleic acid and palmitic acid as the templates; acetonitrile as the porogenic solvent; and allylthiourea as the monomer; and EDGMA as a cross-linker via bulk polymerization. The non-imprinted polymers (NIP) as a control were prepared with the same procedure, but with the absence of template molecule. The synthesized MIPs and NIP were characterized using Fourier Transform Infrared Spectroscopy (FTIR) and the results showed the narrowing of –OH peak which shows that crosslinking has occurred. Field Emission Scanning Electron Microscope-Energy Dispersive X-Ray (FESEM-EDX) was used to analyze the composition of in both MIPs and NIP. The results yielded a composition of C, O, and S. This analysis corresponds to the composition of oleic acid and sulfuric acid as both templates contain -COOH group. These results suggested that the molecularly imprinted polymers can be employed as a potential adsorbent for the removal of oleic acid and palmitic acid from palm fatty acid distillate (PFAD) waste.

Hydroxypropyl methylcellulose/carboxymethyl starch/zinc oxide porous nanocomposite films for wound dressing application

Because of low moisture uptake, water vapor transmission rate, oxygen transmission rate, swelling capacity and no antibacterial activity of hydroxypropyl methylcellulose (HPMC) film, carboxymethyl starch (CMS) and zinc oxide nanoparticles (ZnO-NPs) were incorporated in order to improve its limitations for wound dressing application. The infrared shifted peak of OH stretching and OH bending in HPMC/CMS blended films was detected due to hydrogen bond formation between HPMC and CMS. Scanning electron images of HPMC/CMS blended films exhibited porous structure. In addition, swelling degree, moisture uptake, water vapor transmission rate and oxygen transmission rate of HPMC/CMS blended films with various contents of CMS clearly increased compared to HPMC film. Moreover, HPMC/CMS nanocomposite films loaded with ZnO-NPs showed good antibacterial activity against Staphylococcus aureus and Escherichia coli, revealing their potential for wound dressing application. Percentage of crystallinity, cytotoxicity, mechanical and thermal properties were also examined.

Enhanced tetracycline removal using membrane-like air-cathode with high flux and anti-fouling performance in flow-through electro-filtration system

The membrane-like air-cathodes modified with different polyaniline were prepared using phase inversion method, which possessed dual functions of interception and electrochemical degradation, and showed good conductivity (15.9±0.4 to 25.7±0.5 mS cm-1) and porosity (77.0±0.1 to 87.8±0.1%) compared to the unmodified control one (13.2±0.5 mS cm-1, and 63.1±0.7%). At tetracycline 50mg L-1, the cathode with 25 wt% polyaniline exhibited the highest rejection rate and final removal (71.1% and 92.9%, 35.9% and 31.4% higher than the control), the highest water flux recovery (97.9%), and the lowest attenuation of porosity and conductivity. The modified cathode also showed an autocatalytic effect on H2O2, an obvious ·OH peak appeared on the electron paramagnetic resonance curves. It also had good anti-fouling performance because it exhibited a high durability (the final removal was decreased by 4.0% after 15 cycles) with a long service life of 124 periods (372h, 15.5 d). The tetracycline (0.5mg L-1) removal in the river background was near 100%, and the chemical oxygen demand removal was 91.9%, supporting that it was suitable for treating antibiotics in natural water without adding agents but only for electricity consumption.

Hydrophobic-oleophilic gamma-irradiated modified cellulose nanocrystal/gelatin aerogel for oil absorption

This study highlights the potential use of cellulose nanocrystals (CNCs) from kenaf fiber as a dominant phase for aerogel application. CNCs were modified with methyltrimethoxysilane (MTMS) using the sol-gel method and bound with gamma-irradiated cross-linked gelatin. The properties of the aerogel were studied using Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and water contact angle (WCA). Compression and oil absorption tests were performed to study the aerogels' mechanical and oil absorption properties. A decrease in the OH peak and improved hydrophobicity of CNCs in CNC-MTMS suggested the successful grafting of MTMS onto CNCs, as shown in the FTIR and WCA analyses. Several absorption peaks in the FTIR spectrum shifted, disappeared, or reduced, implying a formation of crosslink between gelatin molecules and hydrogen bonding between CNC and gelatin. FESEM micrographs showed well-organized pores in the gamma-irradiated aerogel, which contribute to increased compressive strength. The oil absorption test indicated that gamma-irradiated CNC-MTMS/gelatin could be a good oil absorbent. Furthermore, this aerogel showed good reusability, where only 4 % of crude oil absorption reduction occurred by the eighth cycle. The combined properties of these aerogel materials can provide good mechanical and oil absorption performance.

Near-Infrared Spectroscopic Study of OH Stretching Modes in Kaolinite and Dickite

Kaolinite and dickite are differently ordered polytypes of kaolinite-group minerals, whose differences are in the stacking mode of layers and ion occupation. Fourier transform infrared spectroscopy was used to collect information about the differences between the two minerals. The common characteristics of kaolinite and dickite are bands near 4530 and 7068 cm−1, which are attributed to the combination of the inner Al-OH stretching vibration and outer Al-OH bending vibration and the overtone of the inner Al-OH stretching vibration, respectively. The difference is that kaolinite has secondary peaks at 4610 and 7177 cm−1, and the secondary peak of dickite is near 4588 cm−1. The OH stretching vibration has the first fundamental overtone of the stretching vibration in the range of 7000–7250 cm−1. In addition to the overtones generated by single OH stretching vibrations, overtones combining different OH stretching vibrations are also found, which are formed by adjacent peaks of OH stretching vibrations. The average factor of the first fundamental overtone with an OH-group stretching vibration is approximately 1.95. The near-infrared spectrum (NIR) of phyllosilicates is closely related to their structure and isomorphism. Therefore, the near-infrared region can distinguish between kaolinite and dickite and provide a basis for deposit research and geological remote sensing.

Bio_Fabricated Levan Polymer from Bacillus subtilis MZ292983.1 with Antibacterial, Antibiofilm, and Burn Healing Properties

The biopolymer levan has sparked a lot of interest in commercial production and various industrial applications. In this study, a bacterial isolate with promising levan-producing ability was isolated from a soil sample obtained from Princess Nourah bint Abdulrahman University in Saudi Arabia. The isolate has been identified and submitted to GenBank as Bacillus subtilis MZ292983.1. The bacterial levan polymer was extracted using ethyl alcohol (75%) and CaCl2 (1%) and then characterized using several approaches, such as Fourier transform infrared spectrometry and nuclear magnetic resonance. The IR spectrum of the levan polymer showed characteristic peaks confirming characteristics of polysaccharides, including a broad stretching peak of OH around 3417 cm−1 and aliphatic CH stretching was observed as two peaks at 2943, and 2885 cm−1. In addition, the FTIR spectrum featured an absorption at 2121 cm−1, indicating the fingerprint of the β-glycosidic bond. Based on 1H and 13C NMR spectroscopy analysis, six unexchanged proton signals related to fructose as a forming monomer of levan were observed. Evaluation of levan’s antibacterial effect against two pathogenic bacteria, S. aureus (ATCC 33592) and E. coli (ATCC 25922), showed inhibition zones of 1 cm and 0.8 cm in diameter, respectively, with MICs of more than 256 μg mL−1 for both strains. Moreover, the antibiofilm property of the levan polymer was assessed and the results showed that the inhibition rate was positively proportional to the levan concentration, as the inhibition percentages were 50%, 29.4%, 29.4%, 26.5%, and 14.7% at concentrations of 2, 1, 0.5, 0.25, and 0.125 mg mL−1, respectively. Levan showed a significant role in burn healing properties since it accelerated the process of healing burn-induced areas in rats when compared with those either treated with normal saline or treated with the cream base only.

Effects of Oxygen Fugacity on Hydroxyl Incorporation in Garnet at 1–3 GPa and 800–1000°C and Implications for Water Storage in the Mantle

AbstractGarnet, an important mineral component in Earth's interior, usually contains minor water as structural OH, but experimental data on OH incorporation in the mineral as a function of chemical and thermodynamic parameters remain rare. In particular, the role of oxygen fugacity (fO2) that is variable in the Earth has not been well assessed. We examine the effects of fO2 on the incorporation of OH at 1–3 GPa and 800–1000°C, by H‐annealing gem‐quality spessartine‐rich, grossular‐rich, and pyrope‐rich garnets. For each type of annealed garnet, the OH peak positions and spectral shapes are the same, suggesting the same OH incorporation mechanism(s). Under identical conditions, spessartine‐rich and grossular‐rich garnets are rich in OH, with solubility orders of magnitudes greater than for pyrope‐rich garnets. Over the studied conditions, the solubility of OH increases with pressure and temperature but decreases with fO2. The negative correlation of fO2 and OH solubility is probably due to the Fe3+ to Fe2+ reduction at more reduced conditions and the coupled OH incorporation in the structure. The effects of fO2 on OH solubility are more significant in Fe‐rich garnets. The ascertained small OH solubility in peridotite garnets, together with comparisons with relevant studies, suggest that mantle garnet is unlikely to be a major water carrier. In combination with literature‐reported positive correlation of fO2 and OH solubility in olivine, the partition coefficient of OH between garnet and olivine in the upper mantle is expected to be redox‐dependent.

Transition Metal Complexes of Schiff Base Ligands Prepared from Reaction of Aminobenzothiazole with Benzaldehydes

Schiff bases have played significant roles in the development of inorganic or coordination chemistry. Three Schiff base (NB, CB and HB) ligands, prepared for the reaction of 2-amino-6-methoxy-benzothiazole with 2-Nitrobenzaldehyde, 2-chlorobenzaldehyde and 2,4-Dihydroxybenzaldehyed, respectively, were investigated for their transition metal complexes, which were prepared by reacting the ligand (2:1 molar ratio) with Co(II), Ni(II), Cu(II), Cd(II), Cr(III) and Fe(III) chlorides. The nature of the interaction between the metal ions and ligands (L) was studied with the aid of magnetic susceptibility, elemental analysis, FTIR and 1H-NMR spectroscopy. Based on the magnetic superstability and elemental analysis results, octahedral structures of the complexes, such as [ML2Cl2] or [ML2Cl(OH)], were proposed for Cu(II), Cd(II), Co(II) and Ni(II) in which the ligand (L:NB, CB or HB) is bidentate through the azomethine and benzothiazole nitrogen. For Cr(III) and Fe(III) complexes, octahedral ML2Cl(OH)2 or ML2(OH)3 structures were proposed, where one ligand is monodentate and the other is bidentate. The azomethine ν(-HC=N-) and 1H-NMR peaks of NB and CB were shifted to a higher frequency and downfield, respectively, upon complexation with metal ions. The bonding of OH groups of HB to Co(II), Cu(II) and Ni(II) enables π-backdonation from these metals to the azomethine of Schiff bases and the consequent shift of ν(-HC=N-) to a lower frequency and changes in the intensity of the 1H-NMR peak of OH. On the other hand, this backdonation was not evidenced in the FTIR of HB complexes with high-charge Cr(III) and Fe(III) ions.

Enhancement of biogas combustion by co-firing dimethyl ether in a gas turbine model combustor

To improve the combustion intensity of biogas which is a renewable gas turbine fuel with methane (CH4) and CO2 as major components, dimethyl ether (DME, CH3OCH3) was used to co-fire with biogas in a gas turbine model combustor in this work. Swirl combustion characteristics of biogas/DME mixtures under different DME contents in fuel mixtures (α) and CO2 contents in biogas mixtures (β) were measured. Numerical simulation and kinetic analysis were performed to provide insights into the effects of DME co-firing and CO2 content on combustion characteristics. It was observed that flame shape and flame size remain almost unchanged with varying DME content and CO2 content at the fixed air flow rate, which are associated with the nearly unchanged flow field. The flame displays a purple color with DME co-firing due to the enhanced formaldehyde (CH2O) chemiluminescence. DME co-firing can effectively improve the flame stability and lower the lean blowout limit (LBO). The decreased LBO is associated with the enhanced fuel reactivity, which results in the reduced ignition delay time and the increased laminar flame speed, OH peak value and high-level OH area. However, increasing CO2 content raises LBO, which is associated with the decreased laminar flame speed, OH peak value and high-level OH area. The ignition delay time can hardly follow the LBO trend with varying CO2 content as it cannot account for the thermal effect caused by CO2 addition. Furthermore, the NO emissions increase with DME co-firing and exceed 20 ppm in pure DME combustion due to the increased temperature level and high-T area, while the amplitude of combustion acoustics is elevated by ∼30–70% with increasing DME content. In contrast, both the NO emissions and amplitude of combustion acoustics attenuate with increasing CO2 content.

Synthesis, kinetics, structure-activity relationship and in silico ADME studies of new diazenyl azo-phenol derivatives against urease, SARS-CoV-2 main protease (Mpro) and ribosomal protein S1 (RpsA) of Mycobacterium tuberculosis

In the present study, a new series of diazenyl azo-phenol derivatives (TC-1 to TC-8) have been synthesized via diazo-coupling approach between substituted aromatic amines and phenol derivatives produced azo–phenol compounds in moderate to good yields (40–80%). The appearance of characteristic prominent peak of azo derivatives i.e. N=N peak at 1500–1400cm−1 and disappearance of NH2 stretch at 3500–3200 cm−1, presence of a broad OH stretch in the range of 3300–3000 cm−1 in FTIR spectra, while presence of OH peak in spectral range of 15–10 ppm and aromatic protons in the region of 8.0–6.0 ppm and disappearance of NH2 peak in 5.0–4.0 spectral region in 1H NMR spectra confirms the synthesis of new diazenyl azo-phenol derivatives. Similarly, appearance of carbon attached with -N=N- group in the range of 149–144 ppm, C−OH in the range of 164–162 ppm, C−N of pyridine ring at 175 ppm, aromatic carbons at 140–108 ppm while aliphatic carbons at 21–20 ppm in 13C NMR spectra give strong indication of synthesis of proposed compounds and HRMS also confirmed the masses of proposed structure of diazenyl azo-phenol derivatives. In case of urease inhibition potential, the in vitro results suggested that the compound TC-6 (IC50 value 0.62 ± 0.04 µM) to be most active compared to the standard drug thiourea (IC50 value 21.44 ± 0.78 µM), kinetic analysis revealed that TC-6 behaved as a mixed-type inhibitor with irreversible mode of action. The SAR showed the stable docked complex due to the presence of dihydroxy hydrogen atoms in TC-6 (-6.01 kcal/mol) and strong binding interactions with the active site residues of the target protein urease (3LA4). The detailed in silico analysis of the diazenyl azo-phenol derivatives (TC-1 to TC-17) against the ribosomal protein S1 (RpsA) of Mycobacterium tuberculosis (4NNI) and main protease (Mpro) of SARS-CoV-2 (6LU7) was also performed and SAR showed that among all the docked compounds, TC-6 and TC-9 showed best docked conformational poses by exhibiting strong interactions with the active site residues of the target proteins (4NNI & 6LU7) with minimum binding energy values i.e. -5.36 kcal/mol and -4.84 kcal/mol respectively. The ADME calculations showed that the synthesized ligands quietly obey rule of five without any considerable violations.

Accelerated toluene degradation over forests around megacities in southern China

Toluene is a typical anthropogenic pollutant that has profound impacts on air quality, climate change, and human health, but its sources and sinks over forests surrounding megacities remain unclear. The Nanling Mountains (NM) is a large subtropical forest and is adjacent to the Pearl River Delta (PRD) region, a well-known hotspot for toluene emissions in southern China. However, unexpectedly low toluene concentrations (0.16 ± 0.20 ppbv) were observed at a mountaintop site in NM during a typical photochemical period. A backward trajectory analysis categorized air masses received at the site into three groups, namely, air masses from the PRD, those from central China, and from clean areas. The results revealed more abundant toluene and its key oxidation products, for example, benzaldehyde in air masses mixed with urban plumes from the PRD. Furthermore, a more than three times faster degradation rate of toluene was found in this category of air masses, indicating more photochemical consumption in NM under PRD outflow disturbance. Compared to the categorized clean and central China plumes, the simulated OH peak level in the PRD plumes (15.8 ± 2.2 × 106 molecule cm−3) increased by approximately 30% and 55%, respectively, and was significantly higher than the reported values at other background sites worldwide. The degradation of toluene in the PRD plumes was most likely accelerated by increased atmospheric oxidative capacity, which was supported by isoprene ozonolysis reactions. Our results indicate that receptor forests around megacities are not only highly polluted by urban plumes, but also play key roles in environmental safety by accelerating the degradation rate of anthropogenic pollutants.

Bidirectional Light-Driven Ion Transport through Porphyrin Metal–Organic Framework-Based van der Waals Heterostructures via pH-Induced Band Alignment Inversion

Bidirectional Light-Driven Ion Transport through Porphyrin Metal–Organic Framework-Based van der Waals Heterostructures via pH-Induced Band Alignment Inversion

Investigation into the Application of Cissus Populnea as Drilling Fluid Additive (Viscosifier) for Water Based Mud

Progress in drilling engineering demands more sophistication from the drilling mud in order to enhance the usage of drilling fluids, hence numerous additives were introduced, and a simple fluid became a complicated mixture of liquid, solid and chemicals. Some of the challenges with the existing drilling fluid additives has to do with compatibility, degradability, safety, cost, and environmental friendliness. Studies have been carried out on the economic benefits of Cissus Populnea which includes in areas of food, medicine, shelter, and transport but much attention has been paid to its applications in the Oil and Gas industry. This study investigates the rheological properties of Cissus Populnea for application as drilling fluid additive (viscosifier) in Water Based Drilling Mud. Fresh roots, stems and leaves of cissus populnea were sourced from Bayara, Bauchi State. Some liquid exudates of cissus populnea were collected and stored for analysis while some of the samples were dried and grinded in to powdered form. Exudate of the samples were characterized by FTIR, XRD and XRF. Drilling mud was formulated with the samples cisssus populnea and bentonite at different temperatures. The rheology of the formulated drilling mud was investigated and compared with that formulated using bentonite and carboxymethyl cellulose (CMC). Results from X-ray Fluorescence analysis show that the chemical composition of Cissus populnea stem and root are similar when comparing their major components (In2O3 and CaO), while that of leaf has its major components to be In2O3 and Cl. Therefore, in this research work, experiments were conducted with only stem and leaf since stem and roots have common features. From the results of FTIR spectra, the stem of cissus populnea has an OH peak wavelength of 3487.42 cm-1 while that of leave is 3340.82 cm-1. The diffractogram of the stem of cissus populnea was observed at 2q = 22.67o which is very close to that of CMC (2? = 20.31o) while the intense peaks of leaf were observed at around 28.65o. Viscosity of cissus populnea was investigated and found to be decreasing with the increase in temperature for stem exudate. While for leaf exudate, the viscosity was rather increasing with the increase in temperature at temperatures below 35 oC and then continue to decrease with the increase in temperature. The outcome of this research has confirmed the applicability of cissus populnea for drilling fluid additives, viscosifier.

Investigation into the Application of Cissus Populnea as Drilling Fluid Additive (Viscosifier) for Water Based Mud

Progress in drilling engineering demands more sophistication from the drilling mud in order to enhance the usage of drilling fluids, hence numerous additives were introduced, and a simple fluid became a complicated mixture of liquid, solid and chemicals. Some of the challenges with the existing drilling fluid additives has to do with compatibility, degradability, safety, cost, and environmental friendliness. Studies have been carried out on the economic benefits of Cissus Populnea which includes in areas of food, medicine, shelter, and transport but much attention has been paid to its applications in the Oil and Gas industry. This study investigates the rheological properties of Cissus Populnea for application as drilling fluid additive (viscosifier) in Water Based Drilling Mud. Fresh roots, stems and leaves of cissus populnea were sourced from Bayara, Bauchi State. Some liquid exudates of cissus populnea were collected and stored for analysis while some of the samples were dried and grinded in to powdered form. Exudate of the samples were characterized by FTIR, XRD and XRF. Drilling mud was formulated with the samples cisssus populnea and bentonite at different temperatures. The rheology of the formulated drilling mud was investigated and compared with that formulated using bentonite and carboxymethyl cellulose (CMC). Results from X-ray Fluorescence analysis show that the chemical composition of Cissus populnea stem and root are similar when comparing their major components (In2O3 and CaO), while that of leaf has its major components to be In2O3 and Cl. Therefore, in this research work, experiments were conducted with only stem and leaf since stem and roots have common features. From the results of FTIR spectra, the stem of cissus populnea has an OH peak wavelength of 3487.42 cm-1 while that of leave is 3340.82 cm-1. The diffractogram of the stem of cissus populnea was observed at 2q = 22.67o which is very close to that of CMC (2θ = 20.31o) while the intense peaks of leaf were observed at around 28.65o. Viscosity of cissus populnea was investigated and found to be decreasing with the increase in temperature for stem exudate. While for leaf exudate, the viscosity was rather increasing with the increase in temperature at temperatures below 35 oC and then continue to decrease with the increase in temperature. The outcome of this research has confirmed the applicability of cissus populnea for drilling fluid additives, viscosifier.

Freezing of Dilute Aqueous-Alcohol Nanodroplets: The Effect of Molecular Structure.

We investigate vapor-liquid nucleation and subsequent freezing of aqueous-alcohol nanodroplets containing 1-pentanol, 1-hexanol, and their 3-isomers. The aerosols are produced in a supersonic nozzle, where condensation and freezing are characterized by static pressure and Fourier transform Infrared (FTIR) spectroscopy measurements. At fixed water concentrations, the presence of alcohol enables particle formation at higher temperatures since both the equilibrium vapor pressure above the critical clusters and the cluster interfacial free energy are decreased relative to the pure water case. The disappearance of a small free OH peak, observed for pure water droplets, when alcohols are added and shifts in the CH peaks as a function of alcohol chain length reveal varying surface partitioning preferences of the alcohols. Changes in the FTIR spectra during freezing, as well as changes in the ice component derived from self-modeling curve resolution analysis, show that 1-hexanol and 1-pentanol perturb freezing less than their branched isomers do. This behavior may reflect the molecular footprints of the alcohols, the available surface area of the droplets, and not only alcohol solubility. The presence of alcohols also lowers the freezing temperature relative to that of pure water, but when there is clear evidence for the formation of ice, the ice nucleation rates change by less than a factor of ∼2-3 for all cases studied.

Effects of Nanosecond Repetitively Pulsed Discharges Timing for Aeroengines Ignition at Low Temperature Conditions by Needle-Ring Plasma Actuator

These days, various national and international research organizations are working on the development of low NOx combustors. The present work describes the experimental and numerical characterization of flow dynamics and combustion characteristics in a rectangular burner. A ring-needle type plasma actuator was developed and driven by a high voltage nanosecond pulsed generator under atmospheric conditions. Smoke flow visualizations and Proper Orthogonal Decomposition (POD) were carried out to identify the relevant flow structures. Electrical characterization of the non-reactive flow was carried out to predict the electrical power and the optimum value of the reduced electric field (EN), which is useful for the implementation of a numerical model for the study of plasma-assisted ignition. A detailed plasma kinetic mechanism integrated with all excited species was considered and validated with experimental studies. Numerical modeling of plasma ignition has been performed by coupling ZDPlasKin with CHEMKIN. Energy and power consumption for methane/air plasma actuation is higher than the air plasma actuation. This could be due to the excitation and ionization of methane that required more energy deposition and power. The mole fraction of O atoms and ozone was higher in the air than the methane/air actuation. However, O atoms were produced in a very short time interval of 10−7 to 10−6 s; in contrast, the concentration of ozone was gradually increased with the time interval and the peak was observed around 10−1 s. Plasma discharges on the methane/air mixture also produced radicals that played a key role to enhance the combustion process. It was noticed that the concentration of H species was high among all radicals with a concentration of nearly 10−1. The concentration peak of CH3 and OH was almost the same in the order of 10−2. Finally, the mixture ignition characteristics under different low inlet temperatures were analyzed for both air and methane/air plasma actuation in the presence of different plasma discharges pulses numbers. Results showed that it is possible to reach flame ignition at inlet temperature lower than the minimum required in the absence of plasma actuation, which means ignition is possible in cold flow, which could be essential to address the re-ignition problems of aeroengines at high altitudes. At Ti = 700 K, the ignition was reached only with plasma discharges; ignition time was in the order of 0.01 s for plasma discharges on methane/air, lower than in case of plasma in air, which permitted ignition at 0.018 s. Besides this, in the methane/air case, 12 pulses were required to achieve successful ignition; however, in air, 19 pulses were needed to ignite.