Non-enzymatic electrochemical detection of creatinine based on a glassy carbon electrode modified with a Pd/Cu2O decorated polypyrrole (PPy) nanocomposite: an analytical approach.

The major constraints of standard enzymatic biosensors are poor long-term storage stability and high cost. Hence, there is extensive research towards fabrication of reliable enzymeless biosensors based on nanomaterials. In this paper, we present the development of an enzymeless electrochemical biosensor for highly precise detection of creatinine. This involves the use of a simple yet effective alternative to the commonly utilized Pd/Cu2O/PPy nanocomposite, which was characterized by different analytical methods. The present electrochemical sensor provides a wide detection range (0.1 to 150 µM), low detection limit (0.05 µM) and high sensitivity (0.207 µA), and is capable of detecting the creatinine level in human urine samples, which are inexpensive. The results are reproducible, and the sensor is stable. The sensor demonstrates good electrocatalytic activity and selectivity towards the detection of creatinine in the presence of various other similar biological entities. When compared to other existing counterparts, the electrocatalytic behaviour of the present sensor is comparable, if not better. So, the present electrochemical sensor for creatinine might be employed as a long-term diagnostic alternative.

Crystallographic investigation, Hirshfeld surface analysis, NLO characterization and experimental spectral (UV and NMR) studies with DFT probe on(R)-9-(2-hydroxy propyl)adenine.

In this study, (R)-9-(2-hydroxy propyl)adenine (HPA) is the molecule of interest for investigation. The XRD from single crystal of HPA has been used to extract its structural features. Since HPA crystallised in a non-centro symmetric space group P212121, its NLO property was studied and it was found to exhibit very good SHG activity. To explore the intermolecular interactions the generated Hirshfeld surface has been investigated along with 2D-fingerprint plots. The experimental electronic and NMR spectra taken in the UV-visible and radio frequency regions respectively for HPA have been corroborated in correlation with theoretical predictions at Density Function Theory using 6-311++g (d, p) basis set. The experimental XRD geometrical parameters, chemical shifts of 13C and 1H and λmax values of HPA fit satisfactorily with the corresponding theoretically obtained numerical values as well as the stimulated spectrograms with the experimental ones. Further to explore the electronic structure, the MESP surface has been generated and investigated. The thermodynamic, kinetic and chemical reactivity features have been explored by means of frontier molecular orbitals of HPA.

Crystallographic, spectral and computational studies on (S)-4-(4-aminobenzyl) oxazolidin-2-one.

The experimental geometry (XRD), vibrational (IR and Raman), electronic (UV-visible) and NMR spectra of (S)-4-(4-Amino-benzyl)-oxazolidin-2-one (ABO) have been corroborated with the corresponding first principle calculated values at DFT using hybrid B3LYP exchange correlation functional invoking 6-311++g(d, p) basis set. The optimized geometrical parameters were found to be in satisfactory agreement with the experimental values obtained from the X-ray diffraction structural features of ABO. The scaled down computed vibrational frequencies with appropriate scaling factors were in good correspondence with the experimental observations. Room-temperature 1H and 13C nuclear magnetic resonance (NMR) studies were supported by advanced density functional theory calculations. The theoretical spectrograms of FT-IR, FT-Raman, 1H NMR, 13C NMR and UV of the title compound have been constructed and compared with experimental spectra and Hirshfeld surface analysis has also been made to study the intermolecular interactions. The electronic structure of the title compound has also been studied in terms of HOMO, LUMO and MESP diagrams.

Chitin and Chitosan Based Hybrid Nanocomposites for Super Capacitor Applications.

In this paper, we report a facile low-cost synthesis of the chitin and chitosan-based hybrid nanocomposites for supercapacitors. The chitosan and chitin based hybrid composites functional group analysis, structural, optical and morphological properties were characterized using FTIR spectroscopy, Raman spectroscopy, UV-vis spectroscopy and scanning electron microscopy (SEM), respectively. Specific capacitance values of hybrid composites were calculated using cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge­discharge analysis. The hybrid composites asymmetric supercapacitor performance was perceived in the range of −0.2 to 1.0 V. The specific capacitance value was achieved at 542.63 F g−1 at current density value of 0.1 A g−1 for CH-GO-ZnO/PANI hybrid composites. The prepared hybrid nanocomposites exhibit good supercapacitive performance and long-term cycle stability. These results demonstrate the potential of the CH-GO-ZnO/PANI hybrid nanocomposites as a high-performance supercapacitors.

A highly sensitive electrochemical biosensor for catechol using conducting polymer reduced graphene oxide-metal oxide enzyme modified electrode.

The fabrication, characterization and analytical performances were investigated for a catechol biosensor, based on the PEDOT-rGO-Fe2O3-PPO composite modified glassy carbon (GC) electrode. The graphene oxide (GO) doped conducting polymer poly (3,4-ethylenedioxythiophene) (PEDOT) was prepared through electrochemical polymerization by potential cycling. Reduction of PEDOT-GO was carried out by amperometric method. Fe2O3 nanoparticles were synthesized in ethanol by hydrothermal method. The mixture of Fe2O3, PPO and glutaraldehyde was casted on the PEDOT-rGO electrode. The surface morphology of the modified electrodes was studied by FE-SEM and AFM. Cyclic voltammetric studies of catechol on the enzyme modified electrode revealed higher reduction peak current. Determination of catechol was carried out successfully by Differential Pulse Voltammetry (DPV) technique. The fabricated biosensor investigated shows a maximum current response at pH 6.5. The catechol biosensor exhibited wide sensing linear range from 4×10(-8) to 6.20×10(-5)M, lower detection limit of 7×10(-9)M, current maxima (Imax) of 92.55µA and Michaelis-Menten (Km) constant of 30.48µM. The activation energy (Ea) of enzyme electrode is 35.93KJmol(-1) at 50°C. There is no interference from d-glucose and l-glutamic acid, ascorbic acid and o-nitrophenol. The PEDOT-rGO-Fe2O3-PPO biosensor was stable for at least 75 days when stored in a buffer at about 4°C.

Real-time measurement of stress and damage evolution during initial lithiation of crystalline silicon.

Crystalline to amorphous phase transformation during initial lithiation in (100) Si wafers is studied in an electrochemical cell with Li metal as the counter and reference electrode. During initial lithiation, a moving phase boundary advances into the wafer starting from the surface facing the lithium electrode, transforming crystalline Si into amorphous Li(x)Si. The resulting biaxial compressive stress in the amorphous layer is measured in situ, and it was observed to be ca. 0.5 GPa. High-resolution TEM images reveal a very sharp crystalline-amorphous phase boundary, with a thickness of ∼1 nm. Upon delithiation, the stress rapidly reverses and becomes tensile, and the amorphous layer begins to deform plastically at around 0.5 GPa. With continued delithiation, the yield stress increases in magnitude, culminating in a sudden fracture of the amorphous layer into microfragments, and the cracks extend into the underlying crystalline Si.

Molecular structure, vibrational spectroscopic, first order hyperpolarizability and HOMO-LUMO studies of 7-amino-8-oxo-3-vinyl-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid.

The FT-IR and FT-Raman spectra of 7-amino-8-oxo-3-vinyl-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid (7AVCA) were recorded in the region 4000-400 cm(-1) and 3500-10 cm(-1), respectively. Quantum chemical calculations of energies, geometrical structure and vibrational wavenumbers were carried out by ab initio HF and density functional theoretical methods invoking 6-311G(d,p) basis set. The differences between the observed and scaled wavenumber values of most of the fundamentals are very small. The electric dipole moment (µ) and the first order hyperpolarizability (ß0) values have been computed quantum mechanically. The calculated results show that 7AVCA may have microscopic nonlinear optical (NLO) behavior with non-zero values. A detailed interpretation of the FT-IR and FT-Raman spectra of 7AVCA is reported. The theoretical IR and Raman spectra of 7AVCA have also been constructed. The calculated HOMO and LUMO energies show that the charge transfer occurs within the molecule.

Clinical pharmacokinetics of the BCR-ABL tyrosine kinase inhibitor nilotinib.

This article describes studies that investigated the pharmacokinetics of nilotinib, a highly specific, oral, second-generation BCR-ABL tyrosine kinase inhibitor. After a once- or twice-daily regimen at doses ranging from 50 to 1,200 mg/day in 119 patients with chronic myeloid leukemia (CML), the area under the serum concentration-time curve (AUC) and peak serum concentration (C(max)) of nilotinib were found to be nearly dose proportional up to a dose of 400 mg once daily. Solubility-limited absorption at higher doses was observed, but this was partially overcome by dividing the daily dose into two. For instance, the administration of 400 mg nilotinib twice daily resulted in a 35% increase in AUC as compared to a once-daily dose of 800 mg. Exploratory pharmacodynamic assessment showed a general trend of greater reduction in white blood cell (WBC) levels with increase in nilotinib concentrations. This finding was consistent with the observation of an 82% reduction in WBC levels in patients after a regimen of 400 mg nilotinib twice daily for 15 days. The type and quantity of food intake variably affected nilotinib absorption. When administered after a high-fat meal, the AUC of nilotinib increased by 50% in CML patients (n = 10) and by 82% in healthy volunteers (n = 44).

FT-IR, FT-Raman, ab initio and DFT structural and vibrational frequency analysis of 6-aminopenicillanic acid.

Quantum mechanical calculations of energies, geometries and vibrational wavenumbers of 6-aminopenicillanic acid were carried out by using ab initio HF and density functional theory (DFT/B3LYP) methods with 6-311G(d,p) basis set. The optimized geometrical parameters obtained by HF and DFT calculations are in good agreement with experimental X-ray data. A detailed interpretation of the infrared spectra has also been reported. The theoretical IR and Raman spectrograms have been constructed and compared with the experimental FT-IR and FT-Raman spectra. The differences between the observed and scaled wavenumber values of most of the fundamentals are very small. The thermodynamic parameters have also been computed.

FT-IR and FT-Raman vibrational assignment of 2-bromobenzoic acid with the help of ab initio and DFT calculations.

The vibrational spectra of 2-bromobenzoic acid (2BBA) have been experimentally recorded (FT-IR and FT-Raman) and compared with the harmonic vibrational frequencies calculated at HF and B3LYP level of theories using 6-311+G(d,p) basis set with appropriate scaling factors. The XRD geometrical parameters show satisfactory agreement with the theoretical prediction at Hartree-Fock and B3LYP levels. The scaled vibrational frequencies at B3LYP/6-311+G(d,p) seem to coincide with the experimentally observed values with acceptable deviations. The theoretical spectrograms (IR and Raman) have been constructed and compared with the experimental FT-IR and FT-Raman spectra.

Vibrational spectroscopic studies and DFT calculations of 4-aminoantipyrine.

The pyrazole derivative, 4-aminoantipyrine (4AAP), used as an intermediate for the synthesis of pharmaceuticals especially antipyretic and analgesic drugs has been analyzed experimentally and theoretically for its vibrational frequencies. The FTIR and FT Raman spectra of the title compound have been compared with the theoretically computed frequencies invoking the standard 6-311g(d,p) and cc-pVDZ basis sets at DFT level of theory (B3LYP). The harmonic vibrational frequencies at B3LYP/cc-pVDZ after appropriate scaling method seem to coincide satisfactorily with the experimental observations rather than B3LYP/6-311g(d,p) results. The theoretical spectrograms for FT-IR and FT-Raman spectra of 4AAP have been also constructed and compared with the experimental spectra. Additionally, thermodynamic data have also been calculated and discussed.

Evaluation of dosing regimen of respirable rifampicin biodegradable microspheres in the treatment of tuberculosis in the guinea pig.

OBJECTIVES: The efficacy of rifampicin-loaded polymeric microspheres (RPLGA) delivered to guinea pigs infected with Mycobacterium tuberculosis (H37Rv) was compared with a daily dose of nebulized rifampicin suspension. METHODS: Aerosol-infected animals were subjected to multiple dose or single dose treatment with RPLGA, PLGA microspheres or micronized rifampicin suspension aerosols. For comparison with treatment with suspensions of microspheres, additional groups received daily doses of rifampicin-only suspensions for 20 (20-RIF) and 10 (10-RIF) days. RESULTS: Drug and polymer treated multiple dose groups exhibited significantly lower wet lung weights than untreated animals. Spleen wet weights and viable bacterial counts (VBCs) were much lower for drug microsphere treated animals than for all other groups. In multiple dose studies with rifampicin-only suspensions, wet lung weights for 10-RIF and 20-RIF treated animals were much smaller than controls. Likewise, wet spleen weights of 10-RIF and 20-RIF treated animals were much smaller than controls, consistent with reduced inflammation. Spleen VBC of 20-RIF treated animals was much smaller than controls. No statistical differences were observed in the lung VBC among single dose groups. However, a trend similar to that of the wet weights was observed. CONCLUSIONS: Aerosolized RPLGA reduced most measures of tuberculosis (TB) infection. These studies are further evidence for the potential of inhaled aerosol therapy for the treatment of TB. However, additional studies are required to elucidate underlying mechanisms of action and optimize this route of drug delivery.

FTIR, FT-Raman spectra and ab initio DFT vibrational analysis of 2-bromo-4-methyl-phenylamine.

The FTIR and FT-Raman spectra of 2-bromo-4-methyl-phenylamine (BMP) have been recorded. From the standard geometrical parameters the geometry of BMP was optimized at ab initio and DFT levels of theory with complete relaxation in the potential energy surface using 6-311+g(d,p) and 6-311+g(2df,2p) basis sets. Several thermodynamic parameters were also calculated for the minimum energy conformer at ab initio and DFT level of theories. The harmonic vibrational frequencies were calculated and the scaled values have been compared with experimental FTIR and FT-Raman spectra. Majority of the computed wavenumbers were found to be in good agreement with the experimental observations. The experimental spectra also coincide satisfactorily with those of theoretically constructed bar type spectrograms.

Evaluation of preseparator performance for the 8-stage nonviable andersen impactor.

The preseparator of an Andersen impactor with different coating treatments for a range of particle-size distributions was evaluated. Limited theoretical simulations constrained by simplifying assumptions of the airflow fields in the preseparator and upper stages of an 8-stage Andersen impactor were used to reveal low-velocity and high-pressure regions for potential deposition. These regions were then sampled in subsequent particle deposition experiments. Disodium fluorescein aerosols were sampled with different coating treatments of the preseparator floor. Particles collected at impactor stages determined particle size distributions. Stage deposition was compared between different preseparator treatments (buffer and silicon oil). Collection efficiency in the preseparator followed the pattern buffer > silicon oil > untreated. Statistical differences (P < 0.05) were noted in collection efficiency of large particles (45 micro m-75 microm) in the preseparator. The mass median aerodynamic diameters and geometric standard deviations showed some statistical differences when different preseparator treatments for large particles were used; therefore, preseparator coating was shown to influence performance and thereby estimates of particle size by inertial impaction.

Pseudoaneurysm of femoral artery after revision total hip arthroplasty with a constrained cup.

Delayed vascular injury after revision total hip arthroplasty is a rare and unusual complication. We report a case of a mechanical complication in which migration of a constraining ring locking mechanism used during a revision total hip arthroplasty caused a pseudoaneurysm of the common femoral artery.

Routine follow-up office visits after total joint replacement: do asymptomatic patients wish to comply?

A total of 100 patients presenting for routine office follow-up after total hip or knee arthroplasty completed questionnaires evaluating whether they preferred to come to the office for routine follow-up evaluation or whether they would have preferred an evaluation without an office visit. Of 100 patients, 45 would have preferred not to come into the office for a routine evaluation. They were content to mail completed questionnaires and radiographs to their physicians. The other 55 patients preferred office visits. These 2 groups were comparable for age, sex, height, weight, and number of surgeries (P > .11) Preoperative and postoperative scores were similar between the 2 groups (P > .39). None of the patients that would have preferred not to come in to the office believed that quality of care would be compromised. A significant number (45%) of patients would prefer not to come to the office because of the wages saved and time spared. Routine office visits may be eliminated for these patients through the use of health outcome devices, such as the SF-36, along with routine radiographs. The potential to decrease healthcare costs and increase patient satisfaction warrants the identification of these patients. Assessment of the effect on quality of care with elimination of routine follow-up visits requires further study.

Factors influencing choice of implants in total hip arthroplasty and total knee arthroplasty: perspectives of surgeons and patients.

To determine the factors influencing surgeons' choice of implants for total hip arthroplasty (THA) and total knee arthroplasty (TKA), 650 surveys were mailed to all active members of the American Association of Hip and Knee Surgeons practicing in the United States; 364 surveys (56%) were completed and returned. Analysis revealed that the average number of total hip and total knee replacements performed by the respondents in 1997 was 81 and 97; there was substantial regional variation. The average number of hip implant and knee implant brands used by these surgeons in 1997 was 2.4 and 1.8. Anticipated improvement in clinical results and cost of components were the most frequently listed reasons for changing brands. Surgeons were also queried about cost reduction programs at their particular institution. The most frequently listed strategies for cost reduction of implants included surgeon cost-awareness programs and volume discounting. More than half of the respondents (53.5%) anticipate manufacturers to decrease the cost of implants in the next 2 years. Most of the respondents (93.7%) currently have the ability to choose a particular implant. About half (46.7%) anticipate losing some or all control of this decision in the next 3 years. These respondents foresee their hospitals requiring the use of a discounted implant in the future. An additional survey was completed by 102 consecutive patients scheduled either for primary THA (64) or primary TKA (38) at our institution. When asked about implant selection, 93.1% responded that their orthopaedic surgeon should choose the prosthesis; 5.9% responded that their physician in consultation with the patient should choose the prosthesis. When asked what should be the primary determinant of implant choice, cost or quality, the overwhelming majority (97.1%) chose quality. A small percentage (2.9%) chose cost and quality. No patient chose cost alone. A large number of patients (84.8%) responded that they would pay additional costs if their insurance companies or health maintenance organizations refused to pay for a better but more expensive implant. Most patients realized how expensive components are, and 51% of the respondents correctly estimated the cost of an implant. Orthopaedic surgeons perceive that they are losing control of implant choice in THA and TKA. Cost of implants is one of the most significant factors influencing which implant is chosen. Patients (the true payors), however, overwhelmingly want their surgeons to choose the implant used at surgery, and they want quality, not cost, to be the primary determinant of this decision.