Absorption Spectroscopy Techniques Research Articles

Amine-Functionalized Silane-Assisted Preparation of AgNP-Deposited α-Ni(OH)2 Composite Materials and Their Application in Hg2+ Ion Sensing.

A facile synthetic methodology for the deposition of different concentrations of Ag nanoparticles (AgNPs) on α-Ni(OH)2 sheets (α-Ni1(OH)2-Ag0.5, α-Ni1(OH)2-Ag1, α-Ni1(OH)2-Ag2, and α-Ni1(OH)2-Ag3) is reported using N-[3-(trimethoxysilyl)propyl]diethylenetriamine (TPDT) silane. The TPDT aminosilane facilitates the formation of α-Ni(OH)2 sheets and reduces the Ag+ precursor to AgNPs, leading to the deposition of AgNPs on α-Ni(OH)2 sheets. UV-vis absorption spectroscopy, transmission microscopy analyses, X-ray photoelectron spectroscopy, X-ray diffraction, and attenuated total reflectance-Fourier transform infrared spectroscopy techniques were used to characterize the prepared α-Ni1(OH)2-Ag0.5-3 composite materials. High-angle annular dark-field scanning transmission electron microscopy-energy-dispersive X-ray spectroscopy mapping images and scanning electron microscopy-energy-dispersive X-ray spectroscopy mapping images were recorded to understand the α-Ni1(OH)2-Ag composite sheet materials. The optical sensing property of α-Ni1(OH)2-Ag0.5-3 composite materials toward toxic Hg2+ ions were investigated using a UV-vis absorption spectroscopy technique. The α-Ni1(OH)2-Ag2 composite material showed selective sensing behavior.

Green synthesis of CdWO4 Nanorods with Enhanced Photocatalytic Activity Utilizing Hyphaene Thebaica Fruit

AbstractCdWO4 as one of the metal tungstate family has recently been identified as a strong photocatalyst for the degradation of organic pollutants. Several methods for the synthesis of different CdWO4 forms have been introduced. All these techniques, however, are either costly or environmentally harmful and create tremendous toxic waste. CdWO4 nanorods (NRs) are synthesized using a simple eco‐friendly method, in which for the first time hyphaene thebaica fruit extract is utilized as a reaction stabilizer, as well as the compounds of the extract serve in functionalizing the CdWO4 NRs surface, water is used as a solvent without elevated temperatures involved. The synthesized NRs’ size, structure, morphology, and optical properties are characterized using TEM, XRD, UV‐visible absorption, and Raman spectroscopy techniques. The results demonstrate the successful synthesis of CdWO4 NRs with an average diameter of 40 nm and length of 100 nm. The CdWO4 NRs have high crystallinity, and exhibit absorption in the UV light region. As well, the photocatalytic activities of the as‐synthesized CdWO4 NRs are investigated under UV irradiation, in which Methylene Blue (MB) is used as a model for an organic pollutant. The degradation efficiency of CdWO4 NRs is shown to be 99 % after 90 minutes. The CdWO4 NRs significantly enhance the absorption of light and increase the rate of degradation of MB and the generation and separation of photoinduced charges (i. e. the exciton lifetime). The CdWO4 NRs showed a high‐level degradation rate of MB, as it is fitted with the first‐order kinetic model, this proves that the CdWO4 NRs can have a great potential for the elimination of organic contaminants, and for the treatment of wastewater as a photocatalyst. Moreover, the as‐synthesized CdWO4 NRs can be used in different environmental applications.

Corrosion inhibitory potential of selected flavonoid derivatives: Electrochemical, molecular⋅⋅⋅Zn surface interactions and quantum chemical approaches

Zinc metal corrosion inhibitor potential of some flavonoid derivatives, namely, naringenin (NRNG), morin hydrate (MNHD), and 6-hydroxyflavone (6-HFN), was investigated by measuring their inhibitory activities, determining their thermodynamic and kinetic adsorption mechanistic properties as well as comparing their molecular⋅⋅⋅Zn metal surface interaction strengths. The inhibition efficiencies were evaluated in 1.5 M hydrochloric acid (HCl) environment and different concentrations of the inhibitors (from 2.0 × 10−4 – 1.8 × 10−3 M) using gravimetric and various electrochemical methods at 30–60 °C. The molecular···metal surface interactions were determined using the density functional theory method by using the GGA/RPBE/DNP approach. Electrochemical studies show that 6-HFN and NRNG are the most and least effective corrosion inhibitors, with 77.54 and 70.46 maximum percentage inhibition efficiency, respectively. Atomic Absorption Spectroscopy technique was used to compare the concentration of the zinc ions that remained in the solution after gravimetric analysis in the absence and presence of the inhibitors at 30 °C; it was found that the inhibited solution contained less concentrations of zinc ions as compared to the uninhibited solution. Surface morphology techniques (e.g., 3D microscope) suggest that a localised type of corrosion took place on the metals, and the corrosion damage was minimal in the presence of the inhibitors. FT-IR showed a strong adsorption of the functional groups found in the inhibitor compounds, with CC functional group being strongly retained by all three inhibitors. The flavonoid inhibitor compounds were found to absorb chemically at low temperatures and physically at high temperatures. Langmuir adsorption isotherm was obeyed. The trend for molecular···metal surface interaction strengths follows the trend obtained from experimental findings on inhibition efficiency. Overall, the results suggest that all the molecules investigated are good corrosion inhibitors with a preference for those compounds in which there exists extended electron delocalization through the aromatic rings and in which there are minimal electron-withdrawing groups on the aromatic rings.

Substoichiometric Titania As Viable Supports for Direct Electrodeposition of Electrocatalysts for Fuel-Cell Relevant Reactions

One of the obstacles to long-term performance of fuel cells is the corrosion carbon support for the electrocatalysts. Titania (TiO2), with its robust corrosion resistance, is already used as a catalyst support for a range of reactions. However, with a bandgap of around 3 - 3.4 eV depending on the type of polymorph, it is too insulating to serve as an electrocatalyst support. In this study, we explored the electrical and the corrosion-resistance properties of substoichiometric titania, specifically the Ti2O3 and the Ti3O5 phases, in order to assess whether they may be as plausible carbon-free supports for electrocatalysts. Furthermore, we investigated the efficacy of synthesizing low-dimensional Pt, Pd, and combined Pt-Pd based catalysts directly onto substroichimetric titania through iterative electrodeposition steps. The influence of the electrodeposition parameters on the physicochemical and electrochemical properties of Pt particles was investigated using x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), x-ray absorption spectroscopy (XAS) and cyclic voltammetric techniques. Along with CV analysis, XPS confirmed the successful deposition of (Pt,Pd)-based electrocatalysts onto Ti2O3 and Ti3O5 supports. XAS confirmed that the local atomic structure of the catalysts exhibited the crystalline order expected from Pt and Pd. SEM analysis showed that the electrochemical deposition conditions used in this work favored the formation of particles with hierarchical fractal-like morphologies. Accelerated stress testing (AST) for the oxygen reduction reaction (ORR) using modified DOE protocols were performed to investigate the catalyst stability. After 30K AST cycles, the active electrocatalyst area retained relative to the as-prepared catalysts was ~14 and 22% for electrocatalysts electrochemically deposited on Ti2O3 and Ti3O5, respectively. Figure 1

(Digital Presentation) Correlative Evaluation Between Water Concentration and Voltage Fluctuation of PEFC Under Low-Humidity and Load-Change Operations Based on Laser Spectroscopy

Low-humidity and load-change operations of polymer electrolyte fuel cells (PEFCs) often tend to induce the excessive voltage drop called “undershoot”. Especially when the load current rapidly increases in steps, the strong electro-osmotic drag dehydrates the electrolyte membrane and deteriorates the proton conductivity, resulting in a temporal increase in ohmic loss. To identify a factor for causing undershoot, it is necessary to precisely grasp the transient water behavior within PEFCs operated under load-change conditions. In the previous works, several researchers vigorously explored the water vapor distribution along flow fields of working cells with micro gas chromatography (μGC) [1]. Although GC techniques provide more accurate species concentrations, it takes a long time (at least two minutes) to collect a gas sample and identify a species. As an alternative approach, the authors have developed a single-ended fiber-optic sensor to measure the in-situ concentration of water vapor within narrow channels of fuel cells at high speed and with high accuracy based on tunable diode laser absorption spectroscopy (TDLAS) [2]. TDLAS is one of the high-speed and high-sensitive absorption spectroscopy techniques which detect the absorbance of a chemical species and identify its concentration using infrared diode laser. This study became able to monitor the transient variation of water vapor concentration in the anode channel of a PEFC during low-humidity and load-change operations using the TDLAS-based fiber-optic sensor and discussed the correlation between the water behavior and the voltage fluctuation. Furthermore, the effects of load current and compression pressure were also investigated.Figs. 1(a) and 1(b) show the dynamic responses of cell voltage and the transient water concentrations in the anode channel of the operating PEFC assembled under two different compression pressures of 1.0 and 2.0 MPa. The electrode area of the experimental cell is 50 mm2. Two separators on both sides have a single-straight channel (1.0 mm width, 1.0 mm depth, 6.0 mm length). Hydrogen (stoichiometry: 2.3@1.0A/cm2, 30%RH) and oxygen (stoichiometry: 9.1@1.0A/cm2, 30%RH) were fed to the anode and cathode channel in the co-flow arrangement. The fiber-optic probe for water detection was positioned at the fractional location of x/L=0.5 on the anode side and the modulated beam emitted from a DFB laser diode (wavelength: 1392.5 nm) was directly injected into the channel. The cell temperature is 70oC. The repetitive current cycling was performed between 0.2 A/cm2 for 23 s and 0.6 A/cm2 for 23 s. In the case of the compression pressure of 1.0 MPa, when the current density increases steeply from 0.2 to 0.6 A/cm2, the strong electro-osmotic drag temporarily reduces the water content on the anode side of the electrolyte membrane and increases the ohmic loss, resulting in the voltage undershoot. After a step increase in the current density, the temporal drop of water vapor concentration in the anode channel can also be observed. When the compression pressure is increased to 2.0 MPa, the porosities of the diffusion media are reduced and the water concentration becomes high especially under the anode rib. Thus, even if the current density is increased stepwise after the repeated current cycles, the water shortage in the anode and the undershoot are not caused. It was noted that the strong compression effectively improves the water retaining on the anode side under low-humidity operations and alleviate the voltage undershoot.

Design Strategies and in situ Infrared, Raman, and X‐ray Absorption Spectroscopy Techniques Insight into the Electrocatalysts of Hydrogen Energy System

The challenging sluggish reaction kinetics of hydrogen energy‐related electrocatalysis can be overcome via exploring electrocatalysts with high‐efficient activity and long‐term durability. However, the deficiency of comprehensive and in‐depth understanding of the evolution of the electrocatalysts, nature of active centers, intermediate species absorbed in the electrocatalysts, and the reaction pathway during the electrocatalytic processes seriously limits the elucidation of the composition/structure–activity relationship of electrocatalysts. To this end, plenty of powerful in situ techniques that can provide atomic/molecular information are employed to bridge the understanding of fundamental mechanisms to the practical development of electrocatalysts. This review summarizes design strategies based on composition regulation and morphology design for tuning the electronic/geometric structures of electrocatalytic materials with improved activity and stability. Moreover, the recent application of in situ infrared, Raman, and X‐ray absorption spectroscopy is elaborated with emphases on tracking the dynamic evolution during electrocatalysis and building a link between the composition/structure and activity of electrocatalysts. Finally, the current challenges and future perspectives for in situ monitoring techniques to gain an understanding more deeply and comprehensively in the hydrogen energy‐related electrocatalysis are proposed. This review provides insights into the rational optimization of electrocatalysts and inspire the unraveling mechanism of the enhanced electrocatalytic performance in future research.

Multicomponent Self-Assembly of Diaminobenzoquinonato-Bridged Manganese(I) Metallosupramolecular Rectangles: Host-Guest Interactions, Anticancer Activity, and Visible-Light-Induced CO Releasing Studies.

The one-pot self-assembly of Mn2(CO)10, a bis-chelated diaminobenzoquinonato (ON∩ON) bridge (L), and a linear ditopic linker (N∩N) (L') has resulted into the formation of M4L2L2'-type manganese(I)-based tetranuclear metallorectangles of the general formula [{(CO)3Mn(μ-η4-L)Mn(CO)3}2(μ-(N-N)2)] (1-8), wherein L is 2,5-bis(n-butylamine)-1,4-benzoquinone (bbbq) and/or 2,5-bis(phenethylamino)-1,4-benzoquinone (bpbq) and N-N is 4,4'-bipyridine (bpy), trans-1,2-bis(4-pyridyl) ethylene (bpe), phenyl-1,4-bis(isonicotinate) (pbin), and N,N'-bis(4-pyridylformamide)-1,4-benzene (bpfb). Metallorectangles 1-8 were characterized by infrared, ultraviolet-visible (UV-vis) absorption, and 1H nuclear magnetic resonance spectroscopies, elemental analysis, and electrospray ionization-mass spectrometry. The molecular and crystal structures of 1•n(CHCl3) and coronene⊂3•coronene were determined by the single-crystal X-ray diffraction method. Host-guest binding abilities of 1, 3, and 7 with coronene, pyrene, and 4,4'-dihydroxybiphenyl were investigated using UV-vis absorption and emission spectroscopic techniques. Formation of host-guest complexes was further confirmed by the single-crystal X-ray structural analysis. Absorption of spectra of these metallorectangles showed high-intensity metal-ligand charge transfer as a broad band in the visible region. In vitro cytotoxicity assays were performed on 1, 3, 5, and 7 against lung, colon, and cervical cancer cells as well as normal cells. Compounds 5 and 7 were identified as visible-light-induced CO-releasing molecules from the myoglobin assay.

Biochemical and spectroscopic characterizations of the oligomeric antenna of the coral symbioticSymbiodiniaceae Fugacium kawagutii.

Light-harvesting antennas in photosynthesis capture light energy and transfer it to the reaction centers (RCs) where photochemistry takes place. The sustainable growth of the reef-building corals relies on a constant supply of the photosynthates produced by the endosymbiotic dinoflagellate, belonging to the family of Symbiodiniaceae. The antenna system in this group consists of the water-soluble peridinin-chlorophyll a-protein (PCP) and the intrinsic membrane chlorophyll a-chlorophyll c2-peridinin protein complex (acpPC). In this report, a nonameric acpPC is reported in a dinoflagellate, Fugasium kawagutii (formerly Symbiodinium kawagutii sp. CS-156). We found that extensive biochemical purification altered the oligomerization states of the initially isolated nonameric acpPC. The excitation energy transfer pathways in the acpPC nonamer and its variants were studied using time-resolved fluorescence and time-resolved absorption spectroscopic techniques at 77K. Compared to the well-characterized trimeric acpPC, the nonameric acpPC contains an 11nm red-shifted terminal energy emitter and substantially altered excited state lifetimes of Chl a. The observed energetic overlap of the fluorescence terminal energy emitters with the absorptionof RCs is hypothesized to enable efficient downhill excitation energy transfer. Additionally, the shortened Chl a fluorescence decay lifetime in the oligomeric acpPC indicate a protective self-relaxation strategy. We propose that the highly-oligomerized acpPC nonamer represents an intact functional unit in the Symbiodiniaceae thylakoid membrane. They perform efficient excitation energy transfer (to RCs), and are under manageable regulations in favor of photoprotection.

Vanillin based colorimetric and fluorometric chemosensor for detection of Cu(II) ion: DFT calculation, DNA / BSA interaction and molecular docking studies

• Vanillin based chemosensor ligand VNP has been designed and synthesized. • The ligand VNP can recognize Cu 2+ ion by colorimetric and fluorometric method. • The ligand VNP and VNP-Cu complex molecular structures are optimized by using DFT calculation. • The binding studies of ligand VNP with biomolecules like DNA, BSA and HSA are performed. • The interaction between the ligand VNP and biomolecules are confirmed by molecular docking studies. Vanillin based Schiff base ligand VNP was designed and synthesized which was used to study the calorimetric detection of Cu 2+ by a colour change from colourless into pink in the presence of other metal ions like Co 2+ , Ni 2+ , Zn 2+ , Pb 2+ , Hg 2+ , Sr 2+ , Cd 2+ , Ca 2+ , Na + , K + , Al 3+ and Cr 3+ in CH 3 CN/H 2 O (9/1, v/v) mixture. Similarly, the ligand VNP also exhibited fluorometric detection of Cu 2+ by “turn-off” process when compared with other metal ions which do not show any notable spectral changes. The ligand VNP is coordinated with Cu 2+ which results the formation of the VNP-Cu complex has the binding stoichiometric ratio at 1:1 as determined by ESI-MS, as well as job’s plot analysis and it was further explained by the CHEQ mechanism. The optimized geometry of the VNP and VNP-Cu complex was analysed by DFT methods, which results confirms the formation of the VNP-Cu complex. The detection range for the Cu 2+ is 2.34 μM. Furthermore, the effective interaction of VNP with the various biomolecules (BSA, HSA and DNA) has been analyzed by absorption and emission spectroscopic techniques. The obtained results were clearly indicates that the interaction between the VNP and biomolecules have better binding ability and which is confirmed by molecular docking studies.

Lead in Breast Milk of Nursing Mothers Working in Agricultural Farms

Aim: To detect lead in breast milk of mothers working in agricultural farms adjacent to Bahawalpur, Pakistan. Study design: Descriptive study Methods: This study was conducted in the Physiology and cell biology department of, University of Health Sciences (UHS), Lahore after obtaining consent from ethical review board of UHS, Lahore. Total 91 lactating female farm workers were selected for this study who had been working in the farm for one year in last three years. Five to six ml of breast milk was obtained from each lady. Samples underwent the process of dry digestion at 500°C for 4 hours. White ash obtained was mixed with deionized solution and inductively coupled plasma spectroscopy was used to detect the lead levels in milk samples of nursing mothers Results: Out of 91 samples, lead levels were detected in 42 samples (46.15%). The mean (mean±SD) values of milk lead (n=42) were 781.49±1034.33µg/l. Family history of intellectual disability was significantly associated with milk concentrations of lead (p = 0.046). Conclusion: Present study concludes that the level of milk lead is found to be considerably higher in nursing mothers working in agricultural farms as compared with the levels reported by others from different countries. Key words: Inductively coupled plasma spectroscopy, lead, breast milk, graphite Furnace Atomic Absorption Spectrometry technique

Heavy metal (Pb, Cd, Zn, Cu) concentration in Red Blood Cockle (Anadara granosa) sold at local markets in Uttaradit Province, Thailand

The objectives of this study were to determine the concentration of heavy metals such as lead (Pb), cadmium (cd), zinc (Zn) and copper (Cu) in red blood cockles sold at local markets in Uttaradit province, Thailand. The red blood cockles were collected and randomly obtained from 5 local markets in Uttaradit province, Thailand-total 50 samples (10 samples from each local markets). The samples were analyzed using Atomic absorption spectrometry technique. The results showed that the average concentration of lead Pb was 0.5107±0.1039 mg/kg dry weight which does not exceed the specified standard. The average concentration of cadmium (Cd) was 0.7882±0.2535 mg/kg dry weight which does not exceed the specified standard, the average concentration of zinc (Zn) was 50.812±5.2684 mg/kg dry weight which does not exceed the specified standard and the average concentration of copper (Cu) was 4.593±0.6082 mg/kg dry weight which does not exceed the specified standard of the Thailand Food and Drug Administration of and that of the United States Food and Drug Administration.

Photophysical properties of levofloxacin and norfloxacin drugs and their fluorescence quenching mechanism with caffeine

Levofloxacin and norfloxacin are drugs used to treat various infections originating from bacterial species. In this research, the photophysical properties of the drugs were investigated using ultraviolet–visible absorption and fluorescence spectroscopic techniques. The results indicated the fluorescence quantum yields, lifetime, and non-radiative decay of the drugs are affected by solvent polarity and drug concentration. The binding mechanism of levofloxacin–caffeine and norfloxacin–caffeine were determined using the fluorescence quenching method. The quenching of drugs induced by caffeine is due to ground state complexes. The binding occurs spontaneously due to electrostatics, hydrogen and Van der Waals force play a major role in the reaction.

Heterometallic Molecular Complexes Act as Messenger Building Units to Encode Desired Metal-Atom Combinations to Multivariate Metal-Organic Frameworks.

A novel synthetic approach is described for the targeted preparation of multivariate metal–organic frameworks (MTV-MOFs) with specific combinations of metal elements. This methodology is based on the use of molecular complexes that already comprise desired metal-atom combinations, as building units for the MTV-MOF synthesis. These units are transformed into the MOF structural constituents through a ligand/linker exchange process that involves structural modifications while preserving their originally encoded atomic combination. Thus, through the use of heterometallic ring-shaped molecules combining gallium and nickel or cobalt, we have obtained MOFs with identical combinations of the metal elements, now incorporated in the rod-shaped secondary building unit, as confirmed with a combination of X-ray and electron diffraction, electron microscopy, and X-ray absorption spectroscopy techniques.

Experimental Investigation on Self-Excited Thermoacoustic Instability in a Rijke Tube

The experimental investigations into the thermoacoustic instability in a Rijke tube are presented. In order to capture the dynamics of the temperature, a single-ended tunable diode laser absorption spectroscopy (TDLAS) technique was developed, with a measurement rate of 5 kHz. The temperature was found to fluctuate periodically at a dominant frequency of 230 Hz, corresponding to the fundamental frequency of the Rijke tube used in the experiment. The flame chemiluminescence was detected by a high-speed camera to demonstrate flame response to thermoacoustic instability. It was evident that the flame front stretched regularly and had jagged edges. To quantitate the fluctuations of chemiluminescence intensity, the relative area was defined. According to the result, the intensity also oscillated at 230 Hz. Furthermore, the same feature was found in regard to pressure at the exit of the Rijke tube. Compared with temperature and chemiluminescent intensity, the pressure oscillations presented the most approximate standard waveform, as they suffered the least disruptions. The results indicated that the dominant frequencies of temperature, chemiluminescent intensity and pressure were consistent, in accordance with the fundamental frequency of the Rijke tube in the experiment. In addition, etalon effects on the TDLAS signals were mitigated efficiently by a lowpass filter.

Ternary boron carbon nitrides hollow nanotubes with tunable p-n homojunction for photo-assisted uranium extraction: A combined batch, EXAFS and DFT calculations

Light-driven catalysis-assisted uranium extraction from seawater opens up a promising avenue to enhance the extraction capacity, kinetics, and selectivity for uranium removal. Herein, we report novel ternary boron carbon nitride hollow nanotubes (BCN-HNTs) with tunable p-n homojunction as metal-free photocatalyst for efficient uranium extraction. Relying on the density functional theory calculations, in conjunction with other spectral analyses, we distinguish the six-membered carbon rings introduced in h-BN to form a tunable p-n homojunction. Accordingly, the BCN-HNTs exhibit a remarkable U(VI) removal rate of ＞95% under a wide range of uranium concentrations. By virtue of the X-ray absorption spectroscopy technique, we identify the conversion of 3Oax-U-4Oeq moieties into the 2Oax-U-3Oeq moieties during the transition from dark to light conditions, further verifying the reduction of high-valent uranium. In addition, we find that the introduction of carbon into h-BN lattice enhances the adsorption energy for uranium species, thereby improving the extraction capacity of uranium.

MXene-Derived 3D Defect-Rich TiO2@Reduced Graphene Oxide Aerogel with Ultrafast Carrier Separation for Photo-Assisted Uranium Extraction: A Combined Batch, X-ray Absorption Spectroscopy, and Density Functional Theory Calculations.

Encapsulation of nano-semiconductor materials in three-dimensional (3D) adsorbents to build a typical semiconductor-adsorbent heterostructure is a forward-looking strategy for photo-assisted uranium extraction. Here, we develop 3D MXene-derived TiO2(M)@reduced graphene oxide (RGO) aerogel for photo-assisted uranium extraction. Theoretical simulations demonstrate that oxygen vacancies on TiO2(M) tailor the energy level structure and enhance the electron accumulation at gap states of TiO2(M), thereby further realizing the spatial separation efficiency of electron-hole pairs by the Schottky junction. By virtue of the in situ X-ray photoelectron spectroscopy spectrum, we identify that photogenerated electrons generated over TiO2(M) were transferred to graphene oxide aerogel by the Schottky junction. Accordingly, TiO2 (M)@RGO aerogel presents a considerable removal efficiency for U(VI) with a removal ratio of 95.7%. Relying on the X-ray absorption spectroscopy technique, we distinguish the evolution of 2H2O-2Oax-U-5Oeq into H2O-2Oax-U-3Oeq from dark to light conditions, further confirming the reduction of high-valent uranium. This strategy may open a paradigm for developing novel heterojunctions as photocatalysts for selective U(VI) extraction.

Photoacoustic Detection of Pollutants Emitted by Transportation System for Use in Automotive Industry

In photoacoustic spectroscopy, the signal is inversely proportional to the resonant cell volume. Photoacoustic spectroscopy (PAS) is an absorption spectroscopy technique that is suitable for detecting gases at low concentrations. This desirable feature has created a growing interest in miniaturizing PA cells in recent years. In this paper, a simulation of a miniaturized H-type photoacoustic cell consisting of two buffer holes and a resonator was performed in order to detect CO, NH3, NO, and CH4 pollutants. These gases are the main components of the air pollutants that are produced by the automotive industry. The linear forms of the continuity, Navier–Stokes equations, and the energy equation were solved using the finite element method in a gaseous medium. The generated pressure could be measured by a MEMS sensor. Photoacoustic spectroscopy has proven to be a sensitive method for detecting pollutant gases. The objectives of the measurements were: determining the proper position of the pressure gauge sensor; measuring the frequency response; measuring the frequency response changes at different temperatures; studying the local velocity at the resonant frequency; and calculating the quality factor. The acoustic quality coefficient, acoustic response (pressure), local velocity, frequency response, and the effect of different temperatures on the frequency response were investigated. A frequency response measurement represents the fact that different gases have different resonance frequencies, for which CO and NO gases had values of 23.131 kHz and 23.329 kHz, respectively. The difference between these gases was 200 Hz. NH3 and CH4 gases with values of 21.206 kHz and 21.106 kHz were separable with a difference of 100 Hz. In addition, CO and NO gases had a difference of 2000 Hz compared to NH3 and CH4, which indicates the characteristic fingerprint of the designed cell in the detection of different gases. Better access to high-frequency acoustic signals was the goal of the presented model in this paper.

Unveiling the atomic position of C in Mn5Ge3Cx thin films

Heavily carbon-doped ${\mathrm{Mn}}_{5}{\mathrm{Ge}}_{3}$ is a unique compound for spintronics applications as it meets all the requirements for spin injection and detection in group-IV semiconductors. Despite the great improvement of the magnetic properties induced by C incorporation into ${\mathrm{Mn}}_{5}{\mathrm{Ge}}_{3}$ compounds, very little information is available on its structural properties and the genuine role played by C atoms. In this paper, we have used a combination of advanced techniques to extensively characterize the structural and magnetic properties of ${\mathrm{Mn}}_{5}{\mathrm{Ge}}_{3}{\mathrm{C}}_{x}$ films grown on Ge(111) by solid phase epitaxy as a function of C concentration. The increase of the Curie temperature induced by C doping up to 435 K is accompanied by a decrease of the out-of-plane $c$-lattice parameter. The Mn and C chemical environments and positions in the ${\mathrm{Mn}}_{5}{\mathrm{Ge}}_{3}$ lattice have been thoroughly investigated using x-ray absorption spectroscopy techniques (x-ray absorption near-edge structures and extended x-ray absorption fine structures) and scanning transmission electronic microscopy (STEM) combined to electron energy loss spectroscopy for the chemical analysis. The results have been systematically compared to a variety of structures that were identified as favorable in terms of formation energy by ab initio calculations. For $x\ensuremath{\le}0.5$, the C atoms are mainly located in the octahedral voids formed by Mn atoms, which is confirmed by simulations and seen for the first time in real space by STEM. However, the latter reveals an inhomogeneous C incorporation, which is qualitatively correlated to the broad magnetic transition temperature. A higher C concentration leads to the formation of manganese carbide clusters that we identified as ${\mathrm{Mn}}_{23}{\mathrm{C}}_{6}$. Interestingly, other types of defects, such as interstitial Ge atoms, vacancies of Mn, and their association into line defects have been detected. They take part in the strain relaxation process and are likely to be intimately related to the growth process. This paper provides a complete picture of the structure of ${\mathrm{Mn}}_{5}{\mathrm{Ge}}_{3}{\mathrm{C}}_{x}$ in thin films grown by solid phase epitaxy, which is essential for optimizing their magnetic properties.

Tetraphosphonic acid functionalized perylenediimide derivative: Synthesis and pH dependent photophysical properties

The synthesis of phosphonic acid functionalized perylene diimide (PDI) molecular architecture has been demonstrated via functionalization at imide position. UV-Vis absorption and fluorescence emission spectroscopic techniques have been employed to investigate the photophysical properties of the novel PDI derivative at different p H (2 to 11). These results demonstrate the fascinating photophysical characteristics based on change in p H from 7 to 2 and 7 to 11 in aqueous medium.

Analysis and Risk Assessment of Insulin-Potentiating Elements in Addua (Balanites Aegyptiaca) Leaf, Seed and Bark.

Purpose: This study investigated certain trace elements having therapeutic properties related to diabetes mellitus and to look into the health risk assessment of the elements. The investigated samples were the bark, leaf and seed of Balanites aegyptiaca, desert date (Addua). These plants are traditionally used in the management of diabetes in Eritrea, Egypt, and Ethiopia.
 Methodology: The elemental analysis was conducted using Flame Emission Photometer and Atomic Absorption Spectroscopy (AAS) techniques. The accuracy of the methods was verified using in-house reference materials (CRMs) and no significant differences were observed between the measured and certified values.
 Findings: The analysis displayed variable concentrations of the different trace elements found to be in the permissible limit defined by WHO. The metals are in the order of decreasing concentrations in the bark sample K > Ca > Mg > Co > Fe > Cu > Zn > Mn. In the leaf, the ranking order is K > Ca > Mg > Fe > Zn > Mn. The seed sample appeared in the order K > Ca > Mg > Fe > Zn > Mn. The THQ for the non-carcinogenic risk were all < 1 for all metals and the various exposure pathways. The trend is same for HI for both children and adults. This is a pointer to the fact that no immediate danger due to presence of potential carcinogens. Furthermore, the study revealed the order of pathway in the following decreasing order HIingestion > HIdermal > HIinhalation and most of all, the HI values for adults generally higher than that of the children. However, this suggests that adults are at greater risks of and could be more susceptible to potential carcinogenic risk from continual exposure.
 Recommendation: The findings calls for concern on the regular use of some of the infusion from this plant.