Fourier Transform Infrared Spectroscopy Peak Research Articles

Annealing led conversion from polypyrrole to carbon nitride nanowires and the fabrication of highly efficient ammonia sensing device

In this work, first of all, polypyrrole (PPy) nanowires have been successfully prepared using template synthesis technique at room temperature by chemical polymerisation of pyrrole within the pores of anodic alumina template. Secondly, the effect of 4 h annealing on morphological, optical and ammonia gas sensing device properties has been studied at 200 °C and 300 °C. The characterization of unanealed and annealed samples was done by using scanning electron microscopy (SEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR) and time resolved photoluminescence. IV measurements are done for studying gas sensing device. The SEM confirms the flexible wire-like morphology of unannealed and annealed nanowires whereas XRD investigation shows the amorphous nature of unannealed and annealed nanowires. Characteristic peaks of FTIR confirm the formation of PPy nanowires synthesized at room temperature and transition from polypyrrole to carbon nitride nanowires after annealing PPy nanowires at 200 and 300 °C. The transition from PPy to CNx nanowires after annealing is proved by the characteristic FTIR peaks corresponding to C=C and C=N bond and the time resolved photoluminescence spectra recorded at different wavelengths corresponding to polypyrrole and carbon nitride well known transitions. I–V studies of nanowires show the increase in sensitivity of annealed nanowires towards NH3 at about thousand times than that of unannealed nanowires.

Enterococcus species for the one-pot biofabrication of gold nanoparticles: Characterization and nanobiotechnological applications

In the current work, cell-free extracts of four strains of non-pathogenic Enterococcus species of food origin, were studied for the green synthesis of gold nanoparticles (AuNPs), and characterized by UV–Vis absorption spectroscopy, Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). The AuNPs were evaluated for their Anopheles gambiae larvicidal, dye degradation, antioxidant and thrombolytic activities. The blue-black colloidal AuNPs which absorbed maximally at 549–552nm were nearly spherical in shape, and crystalline in nature with size of 8–50nm. The EDX spectra showed formation of AuNPs to the tune of 89–94%. The prominent FTIR peaks obtained at 3251–3410, 2088 and 1641–1643cm−1 alluded to the fact that proteins were involved in the biofabrication and capping of AuNPs. AuNPs degraded methylene blue and malachite green by 24.3–57.6%, and 88.85–97.36% respectively in 24h, whereas at 12h, larvicidal activities with LC50 of 21.28–42.33μg/ml were obtained. DPPH scavenging activities of 33.24–51.47% were obtained for the biosynthesized AuNPs. The AuNPs prevented coagulation of blood and also achieved 9.4–94.6% lysis of blood clot showing potential nanomedical applications. This study has presented an eco-friendly and economical synthesis of AuNPs by non-pathogenic strains of Enterococcus species for various nanobiotechnological applications.

Magnetic substrate supported ZnO-CuO nanocomposite as reusable photo catalyst for the degradation of organic dye

Magnetic substrate supported heterogeneous nanocatalysts are emerging materials in the field of catalysis. In the present study, magnetic iron oxide supported zinc oxide – copper oxide nanoparticles were synthesised, characterised and evaluated for their photo catalytic activity. Iron oxide nanoparticles were synthesised by simple chemical co-precipitation method and coated with silica by conventional Stober’s method then the surface was decorated with with ZnO-CuO nanocomposite. The obtained nanocomposite was characterised by X-ray diffraction (XRD), Fourier transform infrared spectroscopy(FTIR), Scanning Electron Microscopy (SEM) and Energy-Dispersive Spectra (EDS). The XRD results confirmed the spinal crystal structure of Fe3O4 and well matches with the peaks of ZnO and CuO. FTIR peak at 1090 cm-1confirmed the presence of Si and peaks below 1000 cm-1 confirmed the presence of metals like Fe, Zn and Cu. SEM results confirmed the spherical and cubic mixed morphology of the nanocomposite. EDAX confirmed the presence of all the elements with high purity. Photocatalytic activity of the nanocomposite was evaluated for degradation of Indigo carmine(IC) dye under UV-visible light irradiation. Indigo Carmine dye was degraded within 2 hrs. The catalyst was easily recovered by applying external magnetic and reused couple of times.

Effect of GGBS and curing temperature on microstructure characteristics of lightweight geopolymer concrete

Cement replacement by supplementary cementitious materials has been gaining momentum as a sustainable mechanism to reduce greenhouse gas emissions while also recycling industrial by-products. This paper presents the development and microstructure characterization of fly ash-based lightweight geopolymer concrete incorporating ground granulated blast furnace slag (GGBS). Concrete samples were prepared with 0%, 25% and 50% GGBS replacement and cured at 30°C, 60°C, and ambient temperature. While dune sand and lightweight expanded clay were used as aggregates, a mixture of sodium silicate and sodium hydroxide served as the alkaline activation solution. Microstructure evaluation was carried out at 7 and 28 days employing scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). Residual fly ash and GGBS were identified in the concrete and bonded to geopolymeric reaction products. The microstructure highlighted the formation and coexistence of aluminosilicate hydrate and aluminum-rich calcium silicate hydrate with traces of sodium. Subsequent polymerization was also verified by an increase in FTIR and DSC peaks.

Shape- and Size-Controlled Synthesis of Silver Nanoparticles Using Aloe vera Plant Extract and Their Antimicrobial Activity.

Biogenic synthesis of silver nanoparticles (AgNP) was performed at room temperature using Aloe vera plant extract in the presence of ammoniacal silver nitrate as a metal salt precursor. The formation of AgNP was monitored by UV-visible spectroscopy at different time intervals. The shape and size of the synthesized particle were visualized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations. These results were confirmed by X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses and further supported by surface-enhanced Raman spectroscopy/Raman scattering (SERS) study. UV-visible spectrum has shown a sharp peak at 420 nm and further evidenced by FTIR peak profile (at 1587.6, 1386.4, and 1076 cm−1 with corresponding compounds). The main band position with SERS was noticed at 1594 cm−1 (C–C stretching vibration). When samples were heated under microwave radiation, AgNP with octahedron shapes with 5–50 nm were found and this method can be one of the easier ways to synthesis anisotropic AgNP, in which the plant extract plays a vital role to regulate the size and shape of the nanoparticles. Enhanced antibacterial effects (two- to fourfold) were observed in the case of Aloe vera plant protected AgNP than the routinely synthesized antibiotic drugs.Graphical Shape and size-controlled synthesis of silver nanoparticles using Aloe vera plant extract Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-016-1725-x) contains supplementary material, which is available to authorized users.

SYNTHESIS AND CHARACTERIZATION OF TOLUENE SULFONIC ACID (TSA)-DOPED POLYPYRROLE NANOPARTICLES: EFFECTS OF DOPANT CONCENTRATIONS

<p class="TRANSAffiliation"><span>Nanoparticles of the conducting polymer polypyrrole in toluene sulfonic acid (PPy/TSA) were synthesized and characterized. The polymerization was process carried out in situ using ammonium persulfate (APS) as an oxidant. The particles were synthesized by varying the dopant concentration of <em>para</em>-toluene sulfonic acid over five sulphonic acid concentrations. The main objective of this study was to examine the effect of TSA dopant concentrations on the properties of polypyrrole nanoparticles. Understanding nature and characteristics of polypyrrole/TSA nanoparticles are important in determining whether the nanoparticles have the potential to be a component in the manufacture of fuel cells. The conducting polymer particles synthesized in this study were characterized using a particle analyzer, X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), spectroscopy UV-visible (UV-vis), thermogravimetric analysis (TGA) and electrical conductivity measurement. XRD shows that the particles generated possessed an amorphous structure, as also indicated by SEM images revealing the formation of aggregated and granular composite particles. Furthermore, the FTIR peak between 1273 and 1283cm<sup>-1</sup> indicated that sulfonic acids (SO<sub>3</sub><sup>-</sup>) groups were present in the structure of PPy. The size of the PPy/TSA nanoparticles was determined to be approximately 24-51 nm, and their conductivity measured to be 1.3 x 10<sup>-1</sup> S/cm.</span></p>

Biosynthesis and characterization of silver nanoparticles (AgNPs) using marine bacteria against certain human pathogens

The present work investigates the synthesis of silver nanoparticles (AgNPs) by biological method using marine bacteria. The minimum inhibitory concentration (MIC) test was performed to find the inhibitory concentration of AgNO3 against marine bacterial isolate. After MIC study, the biogenic AgNPs was prepared through marine bacterial isolate and characterized by using UV-visible spectroscopy, Scanning Electron Microscopy (SEM), X Ray Diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). From the UV-visible spectroscopy, the absorption peak was found at 420 nm. In SEM image, it is confirmed that the sample contains spherical shaped silver nanoparticles and most of the particles were below 100 nm in size. In XRD analysis, it was confirmed that the silver nanoparticles are crystalline in nature, which was confirmed by the FTIR peak at 518 cm-1 corresponding to the Ag vibration present in crystalline structure. The antimicrobial activity of silver nanoparticles was determined by disk diffusion method, and found that silver nanoparticles have significant antibacterial activity against most of the pathogens.

Rapid degradation of phenol by ultrasound-dispersed nano-metallic particles (NMPs) in the presence of hydrogen peroxide: A possible mechanism for phenol degradation in water

The present study was carried out to investigate the degradation of phenol by ultrasonically dispersed nano-metallic particles (NMPs) in an aqueous solution of phenol. Leaching liquor from automobile shredder residue (ASR) was used to obtain the NMPs. The prepared NMPs were analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and by X-ray diffraction (XRD). The SEM images show that the diameters of the NMPs were less than 50 nm. An SEM-EDX elemental analysis reveals that Fe was the most commonly found element (weight %) in the NMPs. The FTIR and XRD peaks indicate the presence of metals oxides on the surfaces of the NMPs. The results of the XPS analysis indicate that various elements (e.g., C, O, Zn, Cu, Mn, Fe) are present on the surfaces of the NMPs. The effects of the NMP dose, the initial solution pH, and of different concentrations of phenol and H2O2 on the phenol degradation characteristics were evaluated. The results of this study demonstrate that phenol degradation can be improved by increasing the amount of NMPs, whereas it is reduced with an increase in the phenol concentration. The degradation of phenol by ultrasonically dispersed NMPs followed the pseudo-first-order kinetics. The probable mechanism of phenol degradation by ultrasonically dispersed NMPs was the oxidation of phenol caused by the hydroxyl radicals produced during the reaction between H2O2 and the NMPs during the ultrasonication process.

An in situ study of amine and amide molecular interaction on Fe surfaces

The interfacial bondings formed between N,N′-diethylmethylamine, N-methyldiethanolamine and N,N′-dimethylsuccinamide molecules with iron surfaces have been investigated using Fourier transform infrared spectroscopy (FTIR) and electrochemical spectroscopies. In this case, the interfacial interactions have been evaluated by analyzing ex situ FTIR peaks and probing potential variations upon molecular interactions to Fe surfaces. Moreover, integrated ATR-FTIR and chronovoltammetry analyses in Kretschmann geometry have been employed to probe the interactions between the molecules and Fe surfaces in situ. The results revealed that a charge transfer between molecules and Fe surfaces takes place indicating chemisorption of the molecules on Fe surfaces. In this case, the interaction of N,N′-diethylmethylamine and Fe surface is negligible. However, N-methyldiethanolamine molecules interact with Fe surfaces through the nitrogen atoms. Interaction of N,N′-dimethylsuccinamide molecules and Fe surface is promoted by nitrogen and carbonyl functional groups. Moreover, interactions of N-methyldiethanolamine and N,N′-dimethylsuccinamide molecules to Fe surfaces are encouraged by application of anodic potentials implying that the molecules and Fe surfaces are charged positively and negatively, respectively.

Impedance Spectroscopy And Conductivity Studies Of CdCl2 Doped Polymer Electrolyte

Polyvinyl alcohol (PVA) and Polyvinyl Pyrrolidone (PVP) based polymer electrolytes for different loading wt% of CdCl2 were prepared by solution casting. The structural complexation was confirmed and interlayer spacing (d) was evaluated by using X-ray diffraction (XRD) study. The chemical bonding between polymer and salt was identified by using Fourier transform infrared spectroscopy (FTIR) technique. The FTIR peak at 3402.43 cm -1 in addition of PVP in PVA/CdCl2 composite demonstrates the grafting between two polymers. The presence of ionic bright channels and variation in morphology for different loading wt% of CdCl2 was confirmed by scanning electron microscope (SEM) and was also verified by Atomic force microscopy (AFM) micrographs. The analysis of impedance spectroscopy represented by semicircular pattern is driven by conduction mechanism and correlated with electrical conductivity. The enhanced AC conductivity of polymer electrolyte is directly proportional to frequency (50Hz-1MHz). The maximum value of DC conductivity 1.65x10 -5 S/m evaluated from Arrhenius plots and attribute to high mobility of free charges at higher temperature. The evaluated results of structural, morphological and electrical properties of present composites make the present research good for electrochemical devices.

Growth and Characterization of High-Quality Dielectric Sputtered Zinc Oxide Films from the First Principle

In this article, we investigate the effect of thermal treatment on a piezoelectric material, zinc oxide, which has found numerous applications in sensors and actuators. Even though the exact mechanisms rendering electrical properties are less known, we suspect that the thermal treatments are responsible for improvement of electrical characteristics of the deposited thin films. We establish that the thermal agitation is responsible for improvement of orders of magnitude in electrical characteristics of sputtered ZnO thin films. The surface quality of the thin films deposited is process dependent. ZnO films were deposited using a dielectric sputtering method, on oxidized silicon 100 n-type wafers. Further, these films were thermally annealed in oxygen ambient at 600 °C in a tube furnace with 2 mL/min pressure. It is observed that, after thermal annealing, the quality of the films is improved by orders of magnitude. The luminance, crystalline quality, and surface morphology of these thin films was measured with atomic force microscopy, scanning electron microscopy with BSD detector (BSD-SEM), and Fourier transform infrared spectroscopy (FTIR). The results infer that the film’s surface is very smooth and dense. The surface roughness is improved by 1.3149 nm from 7.882 nm prior to thermal annealing to post-annealing surface roughness with 6.5671 nm. Post-thermal annealing process reveals average grain size was 50 nanometers; the surface roughness is reduced to 6.5671 nm. A significant improvement in electrical current-voltage characteristics was recorded with I-V curve. It is suspected to be due to substantial enhancement in electrical conductivity as a result of thermal treatment and improved spectral response recorded a FTIR peak shift of 1 wave number in total. The FTIR peak shift is suspected to be due to evaporation and reduction in oxygen vacancies due to thermal annealing process. The post-annealed ZnO films will be used for actuation in the future.

Predicting protein aggregation during storage in lyophilized solids using solid state amide hydrogen/deuterium exchange with mass spectrometric analysis (ssHDX-MS).

Solid state amide hydrogen/deuterium exchange with mass spectrometric analysis (ssHDX-MS) was used to assess the conformation of myoglobin (Mb) in lyophilized formulations, and the results correlated with the extent of aggregation during storage. Mb was colyophilized with sucrose (1:1 or 1:8 w/w), mannitol (1:1 w/w), or NaCl (1:1 w/w) or in the absence of excipients. Immediately after lyophilization, samples of each formulation were analyzed by ssHDX-MS and Fourier transform infrared spectroscopy (FTIR) to assess Mb conformation, and by dynamic light scattering (DLS) and size exclusion chromatography (SEC) to determine the extent of aggregation. The remaining samples were then placed on stability at 25 °C and 60% RH or 40 °C and 75% RH for up to 1 year, withdrawn at intervals, and analyzed for aggregate content by SEC and DLS. In ssHDX-MS of samples immediately after lyophilization (t = 0), Mb was less deuterated in solids containing sucrose (1:1 and 1:8 w/w) than in those containing mannitol (1:1 w/w), NaCl (1:1 w/w), or Mb alone. Deuterium uptake kinetics and peptide mass envelopes also indicated greater Mb structural perturbation in mannitol, NaCl, or Mb-alone samples at t = 0. The extent of deuterium incorporation and kinetic parameters related to rapidly and slowly exchanging amide pools (Nfast, Nslow), measured at t = 0, were highly correlated with the extent of aggregation on storage as measured by SEC. In contrast, the extent of aggregation was weakly correlated with FTIR band intensity and peak position measured at t = 0. The results support the use of ssHDX-MS as a formulation screening tool in developing lyophilized protein drug products.

Imidazolium-Based Ionic Liquid Dissolution Influence on Crystallinity of Oil Palm Frond, Oil Palm Trunk and Elephant Grass Lignocellulosic Biomass

Ionic liquid (IL) has been shown to affect cellulose crystalline structure in lignocellulosic biomass (LB) during pretreatment. This research was carried out with two different experimental design involving IL to observe the effect of dissolution in IL on: (A) the crystallinity of cellulose and (B) the dissolution efficiency of LB. For experiment A, the types of IL used in this research were 1-ethyl-3-methylimidazolium Acetate [EMI[A, 1-allyl-3-methylimidazolium Chloride [AMI[C, 1-butyl-3-methylimidazolium Chloride [BMI[C and 1-ethyl-3-methylimidazolium Chloride [EMI[C. The crystallinity degree of LB was investigated before and after pretreatment with IL. The microcrystalline cellulose (MCC) was used as the simulated LB (cellulose content) was dissolved in IL and the crystallinity after the dissolution was analyzed. The temperature (70°C, 80°C, 90°C, 99°C) and concentration ratio of IL with volume/volume (v/v: 10%, 25%, 50%) were varied while the dissolution time remained constant. The crystallinity was analyzed by using Fourier Transform Infrared Spectroscopy (FTIR). The results showed that the dissolution temperature and IL concentration ratio affects the intensity of the FTIR peaks. In experiment B, the dissolution of LB with 1-butyl-3-methylimidazolium Chloride [BMI[C and 1-Ethyl-3-methylimidazolium Chloride [EMI[C as ILs were investigated. Four types of LB involved were Elaeis guineensis species of Oil Palm Trunk (OPT) and Oil Palm Frond (OPF) and Pennisetum purpureum species (elephant grass) originated from Taiwan and India. From the results obtained, the [BMI[C gave better dissolution to biomass.

A Study of the Behavior of HNT with DNA Intercalator Acridine Orange

The interaction of nanomaterials with DNA and proteins is an area of great interest especially in the development of novel biosensors, and recently, it has become the focus of many multidisciplinary researches. DNA intercalating agent acridine orange interrupts the normal function of cellular DNA, leading to the inhibition of gene expressions. Many carcinogenic chemicals damage DNA either by intercalation or by cross-linkage. Numerous repair strategies are available to block the progressive DNA damage caused by DNA intercalators. These strategies aimed to prevent intercalation through the scavenging of the reactive moieties of the intercalators. In this report, we demonstrate binding of halloysite nanotubes (HNT) with a DNA intercalator, acridine orange (AO), through a hydrophobic interaction referred to as “polar bonding.” HNTs are composed of silica on their outer surface and alumina within their inner surface. The inner and outer surfaces of tubular walls confer a resultant negative charge which makes HNT polyanionic in nature, thus enhancing the potential for polar bonding between HNT and amino-substituted AO. This interaction can lead to a metachromatic shift due to π interactions between the aromatic entity of AO and the oxygen plane of the HNT. This shift was confirmed by Fourier transform infrared spectroscopy (FTIR) analysis whereby in the presence of HNT, the intercalator AO, intercalated within the DNA–AO complex, showed affinity for HNT as observed by the shift in FTIR peaks of halloysite nanotubes from 3,623, 1,722, and 1,038 cm−1 to 3,612, 1,706, 1,083, and 963 cm−1.

Synthesis and characterization of conducting polyaniline nanocomposites containing ZnO nanorods

Polyaniline (PANI) based nanocomposites filled with ZnO nanorods were prepared by the chemical oxidative method of the aniline in acid medium with ammonium peroxydisulphate (APS) as an oxidant. The composition, morphology and structure of the polymer and the nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), UV–vis spectroscopy and electrical conductivity. The characteristic FTIR peaks of PANI were found to shift to higher or lower wave number in PANI–ZnO composites due to formation of H-bonding. Different amounts of ZnO nanorods were used to verify this effect on the characteristics of the synthesized materials. These observed effects have been attributed to interaction of ZnO nanorods with PANI molecular chains. XRD results revealed that the crystallinity of PANI was more pronounced after addition of nanorods, while the intensity of the peaks increased by addition of ZnO nanorods. Electrical conductivity of the PANI–ZnO nanocomposite film was found to be smaller than that of the PANI film. The decrease of electrical conductivity in PANI–ZnO films as compared to PANI was attributed to the interfaces formed between oxygen of ZnO nanorods and hydrogen of PANI. Also, TGA results showed that the decomposition of the nanocomposite was less than that of pure polyaniline which confirms the successful fabrication of products. These conductive polymers can be used in commercial paints as an additive.

Novel microwave assisted synthesis of highly doped phase pure Nd:YAG nanopowder

For the first time, the studies on 2 to 10 at.% neodymium (Nd3+) ion doped Yttrium Aluminum Garnet (Nd:YAG) nanopowders obtained by microwave assisted citrate nitrate gel combustion synthesis is described in this work. This paper reports on high doping of Nd3+ ions with retaining the cubic garnet structure of YAG as evidenced from XRD, except the case of 8 at.% doped Nd:YAG. Phase pure YAG formation with 8 at.% Nd3+ doping was explored by using urea and alanine as alternative to citric acid complexing agents. Complete crystallization of YAG as a result of 2 hour thermal treatment at 900 °C under oxygen supply was studied by using Fourier Transform Infra-Red Spectroscopy (FTIR) and X-Ray Diffraction (XRD) techniques. With an increase in the dopant concentration a red shift in the FTIR peaks was observed. Using the XRD data, the cell parameter of Nd3+ (2 to 6 and 10 at.%) YAG was found to increase with an increase in the dopant concentration. The average primary particle size calculated using Scherrer’s equation was ∼25 nm which was additionally supported by Transmission Electron Microscopy (TEM) results yielding particle sizes in the range of ∼25 to 30 nm for all the cases.

Self-Assembled Monolayer Formation on Molybdenum with Octadecyltrichlorosilane and Phenethyltrichlorosilane and Measurement of Molybdenum–Pentacene Interface Properties

The formation of a self-assembled monolayer (SAM) with octadecyltrichlorosilane (OTS) and phenetyltrichlorosilane (PTS) on a molybdenum (Mo) surface and surface properties like surface energy, work function, and roughness were studied. From X-ray photoelectron spectroscopy (XPS) measurement, the native oxide of Mo was confirmed and this could react with trichlorosilane to form a SAM. The formation of OTS and PTS monolayers was confirmed and investigated using contact angle measurement, Fourier transform infrared spectroscopy (FTIR), atomic force microscopy, and XPS. After formation of the SAM, Si–O bond formation was observed with a decreased intensity of the Mo–O bond with XPS. The effect of dipping time for the formation of SAM was monitored with FTIR peak intensity of OTS and PTS and also the change in surface energy. It was confirmed that in the SAM formation with OTS, the hydrophilic surface was transformed into a hydrophobic state, roughness was reduced, and the work function was increased about 0.1 eV. Pentacene thin film deposited on SAM-treated Mo gave a better crystallinity and the contact resistance of Mo–pentacene was reduced.

Fabrication and characterization of Ge nanocrystalline growth by ion implantation in SiO2 matrix

Ge nanocrystallites (Ge-nc) have been formed by ion implantation of Ge+74 into SiO2 matrix, thermally grown on p-type Si substrates. The Ge-nc are examined by Raman spectroscopy, photoluminescence (PL) and Fourier transform infrared spectroscopy (FTIR). The samples were prepared with various implantation doses [0.5; 0.8; 1; 2; 3; 4] × 1016 cm−2 with 250 keV energy. After implantation, the samples were annealed at 1,000 °C in forming gas atmosphere for 1 h. Raman intensity variation with implantation doses is observed, particularly for the peak near 304 cm−1. It was found that the sample implanted with a doses of 2 × 1016 cm−2 shows maximum photoluminescence intensity at about 3.2 eV. FTIR analysis shows that the SiO2 film moved off stoichiometry due to Ge+74 ion implantation, and Ge oxides are formed in it. This result is shown as a reduction of GeOx at exactly the doses corresponding to the maximum blue-violet PL emission and the largest Raman emission at 304 cm−1. This intensity reduction can be attributed to a larger portion of broken Ge–O bonds enabling a greater number of Ge atoms to participate in the cluster formation and at the same time increasing the oxygen vacancies. This idea would explain why the FTIR peak decreases at the same implantation doses where the PL intensity increases.

Formulating the alginate–polyornithine biocapsule for prolonged stability: Evaluation of composition and manufacturing technique

Alginate encapsulation is one of the most widely used techniques for introducing cell-based therapeutics into the body. Numerous encapsulation methodologies exist, utilizing a variety of alginates, purification technologies, and unique polycationic membrane components. The stability of a conventional alginate formulation encapsulated using a commercially available technique and apparatus has been characterized extensively. The current study employs an encapsulation protocol and ultra-pure alginate pioneered at the University of Perugia. The enhanced microcapsules were produced, characterized, and implanted into the brain, peritoneal cavity, and subcutaneous space of Long-Evans rats. After 14, 28, 60, 90, 120, and 180 or 215 days, capsules were explanted and the surface was analyzed using Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Image analysis was carried out to measure changes in diameter and wall thickness. FTIR peak analysis and surface morphology from SEM indicated that the enhanced encapsulation technique and formulation produced a stable biocapsule capable of survival in all sites, including the harsh peritoneal environment, for at least 215 days. Preimplant analysis showed a marked increase in the structural integrity of the enhanced formulation with improved elasticity and burst strength compared with the baseline formulation, which remained stable for less than 60 days. The enhanced microcapsule composition showed advantages in physical strength and longevity, indicating that small changes in encapsulation methodologies and materials selection can dramatically impact the stability and longevity of alginate microcapsules and their contents.

Reaction of acetonitrile with the silicon(0 0 1) surface: A combined XPS and FTIR study

The adsorption of acetonitrile on the Si(0 0 1) surface has been investigated using X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR). XPS and FTIR spectra indicate that adsorbed acetonitrile forms two correlated binding configurations, a C N species with a strong FTIR absorption at 1540 cm −1 and a C C N (ketenimine) species that has a very strong FTIR absorption at 1952 cm −1. The C C N FTIR peak at 1952 cm −1 shows a striking polarization dependence, with the infrared transition dipole almost entirely in the plane of the sample and parallel to the Si Si dimer axis. Our data suggests that the primary C C N structure results from cleavage of two C–H bonds, forming a structure in which the N and terminal C atom are both linked to the surface. Temperature-dependent experiments help to elucidate the complicated reaction mechanism for acetonitrile adsorbing onto the Si(0 0 1) surface. Dosing at higher temperature increases the amount of C C N relative to C N species while heating leads to direct transformation of the C N to the C C N species. Our results indicate that previous studies, which considered only products formed by cleavage of a single C–H bond, have misidentified the primary ketenimine product. A reinterpretation of the earlier results, combined with data presented here, sheds new light onto the products and mechanism of interaction of acetonitrile with Si(0 0 1).