Modeling the effect of subsurface interface defects on contact stiffness for ultrasonic atomic force microscopy

Cataloged from PDF version of article.We present a model predicting the effects of mechanical defects at layer interfaces on the contact stiffness measured by ultrasonicatomic force microscopy(AFM). Defects at subsurface interfaces result in changes at the local contact stiffness between the AFM tip and the sample. Surface impedance method is employed to model the imperfections and an iterative algorithm is used to calculate the AFM tip-surface contact stiffness. The sensitivity of AFM to voids or delaminations and disbonds is investigated for film-substrate combinations commonly used in microelectronic structures, and optimum defect depth for maximum sensitivity is defined. The effect of contact force and the tip properties on the defect sensitivity are considered. The results indicate that the ultrasonicAFM should be suitable for subsurface detection and its defect sensitivity can be enhanced by adjusting the applied force as well as by judicious choice of the AFM tip material and geometry. © 2004 American Institute of Physic

Efficient ammonium removal from aquatic environments by Acinetobacter calcoaceticus STB1 immobilized on an electrospun cellulose acetate nanofibrous web

Cataloged from PDF version of article.A novel biocomposite material was developed by immobilizing an ammonia-oxidizing bacterial strain, Acinetobacter calcoaceticus STB1, on an electrospun porous cellulose acetate (CA) nanofibrous web. Ammonium removal characteristics of the STB1 immobilized CA nanofibrous web were determined at varying initial ammonium concentrations, and removal rates of 100%, 98.5% and 72% were observed within 48 h for 50 mg L-1, 100 mg L-1 and 200 mg L-1 samples, respectively. Most of the ammonia is inferred to be converted into nitrogen or is accumulated as bacterial biomass, as only trace amounts of ammonium were converted into nitrite or nitrate. Reusability test results indicate that, at an initial ammonium concentration of 100 mg L-1, bacteria-immobilized CA nanofibrous webs can be reused for at least 5 cycles. SEM images of the STB1/CA nanofibrous web after five cycles of reuse and rigorous washing demonstrate that bacterial biofilms strongly adhere to nanofiber surfaces

Fourier transform infrared spectroscopy as a novel approach for analyzing the biochemical effects of anionic surfactants on a surfactant-degrading acrobacter butzleri strain

Cataloged from PDF version of article.Anionic surfactant-biodegrading capability of an Arcobacter butzleri strain was analyzed under aerobic conditions. The A. butzleri isolate displayed efficient surfactant-biodegrading capacity for sodium dodecyl sulfate (SDS) at concentrations of up to 100 mg/L in 6 days, corresponding to 99.0% removal efficiency. Fourier transform infrared spectroscopy was applied to observe the effects of varying concentrations of SDS on the biochemistry of bacterial cells. Results suggest that protein secondary structures were altered in bacterial cells at sufficiently high SDS concentrations, concurrent with SDS biodegradation

Accelerated Born-Infeld Metrics in Kerr-Schild Geometry

We consider Einstein Born-Infeld theory with a null fluid in Kerr-Schild Geometry. We find accelerated charge solutions of this theory. Our solutions reduce to the Plebanski solution when the acceleration vanishes and to the Bonnor-Vaidya solution as the Born-Infeld parameter b goes to infinity. We also give the explicit form of the energy flux formula due to the acceleration of the charged sources.Comment: Latex file (12 pp

Dynamics and stability of the Godel universe

We use covariant techniques to describe the properties of the Godel universe and then consider its linear response to a variety of perturbations. Against matter aggregations, we find that the stability of the Godel model depends primarily upon the presence of gradients in the centrifugal energy, and secondarily on the equation of state of the fluid. The latter dictates the behaviour of the model when dealing with homogeneous perturbations. The vorticity of the perturbed Godel model is found to evolve as in almost-FRW spacetimes, with some additional directional effects due to shape distortions. We also consider gravitational-wave perturbations by investigating the evolution of the magnetic Weyl component. This tensor obeys a simple plane-wave equation, which argues for the neutral stability of the Godel model against linear gravity-wave distortions. The implications of the background rotation for scalar-field Godel cosmologies are also discussed.Comment: Revised version, to match paper published in Class. Quantum Gra

Оцінка оновлення основних засобів за рахунок позикових коштів

Оновлення основних засобів є актуальною проблемою сьогодення. Для багатьох підприємств кредити банків є чи не єдиним джерелом коштів на модернізацію виробничих потужностей. В даній статті нами були розглянуті можливості і перспективи приватних фірм для використання з цією метою позикових засобів, оцінений ступінь прозорості банківських установ, річні ставки за інвестиційними кредитами та інші умови їхнього надання.Modernizing of the basic assets is a topical problem of the present. For many business firms bank loans are may be the only source of funds for renewal of production facilities. In the article we have considered the opportunities and prospects for use of borrowed funds by private firms for this purpose, rated the degree of transparency of banking institutions, the annual rates of investment credits and other conditions of their granting

Overview of diagnosis and management of paediatric headache. Part I: diagnosis

Headache is the most common somatic complaint in children and adolescents. The evaluation should include detailed history of children and adolescents completed by detailed general and neurological examinations. Moreover, the possible role of psychological factors, life events and excessively stressful lifestyle in influencing recurrent headache need to be checked. The choice of laboratory tests rests on the differential diagnosis suggested by the history, the character and temporal pattern of the headache, and the physical and neurological examinations. Subjects who have any signs or symptoms of focal/progressive neurological disturbances should be investigated by neuroimaging techniques. The electroencephalogram and other neurophysiological examinations are of limited value in the routine evaluation of headaches. In a primary headache disorder, headache itself is the illness and headache is not attributed to any other disorder (e.g. migraine, tension-type headache, cluster headache and other trigeminal autonomic cephalgias). In secondary headache disorders, headache is the symptom of identifiable structural, metabolic or other abnormality. Red flags include the first or worst headache ever in the life, recent headache onset, increasing severity or frequency, occipital location, awakening from sleep because of headache, headache occurring exclusively in the morning associated with severe vomiting and headache associated with straining. Thus, the differential diagnosis between primary and secondary headaches rests mainly on clinical criteria. A thorough evaluation of headache in children and adolescents is necessary to make the correct diagnosis and initiate treatment, bearing in mind that children with headache are more likely to experience psychosocial adversity and to grow up with an excess of both headache and other physical and psychiatric symptoms and this creates an important healthcare problem for their future life

Methanogens, sulphate and heavy metals: a complex system

Anaerobic digestion (AD) is a well-established technology used for the treatment of wastes and wastewaters with high organic content. During AD organic matter is converted stepwise to methane-containing biogasa renewable energy carrier. Methane production occurs in the last AD step and relies on methanogens, which are rather sensitive to some contaminants commonly found in wastewaters (e.g. heavy metals), or easily outcompeted by other groups of microorganisms (e.g. sulphate reducing bacteria, SRB). This review gives an overview of previous research and pilot-scale studies that shed some light on the effects of sulphate and heavy metals on methanogenesis. Despite the numerous studies on this subject, comparison is not always possible due to differences in the experimental conditions used and parameters explained. An overview of the possible benefits of methanogens and SRB co-habitation is also covered. Small amounts of sulphide produced by SRB can precipitate with metals, neutralising the negative effects of sulphide accumulation and free heavy metals on methanogenesis. Knowledge on how to untangle and balance sulphate reduction and methanogenesis is crucial to take advantage of the potential for the utilisation of biogenic sulphide as a metal detoxification agent with minimal loss in methane production in anaerobic digesters.The research was financially supported by the People Program (Marie Curie Actions) of the European Union's Seventh Framework Programme FP7/2007-2013 under REA agreement 289193

Circulating tumor cells detected by lab-on-adisc: Role in early diagnosis of gastric cancer

[Background] The use of circulating tumor cells (CTCs) as an early diagnostic biomarker and prognostic indicator after surgery or chemotherapy has been suggested for various cancers. This study aimed to evaluate CTCs in patients who underwent gastrectomy for gastric cancer and to explore their clinical usefulness in the early diagnosis of gastric cancer. [Methods] A total of 116 patients with gastric cancer who underwent gastrectomy and 31 healthy volunteers were prospectively included between 2014 and 2015. Peripheral blood samples were collected before gastrectomy, and CTCs were examined using a centrifugal microfluidic system with a new fluid-assisted separation technique. [Results] After creating a receiver operating characteristic curve to identify the discriminative CTC value needed differentiate patients with gastric cancer from healthy volunteers, sensitivity and specificity were nearly optimized at a CTC threshold of 2 per 7.5 mL of blood. Of the 102 persons with a CTC level >= 2 per 7.5 mL of blood, 99 (97.1%) had gastric cancer, and of the 45 persons with a CTC level <2 per 7.5 mL of blood, 28 (62.2%) were healthy controls. Accordingly, the sensitivity and specificity for the differentiation of patients with gastric cancer from healthy controls were 85.3% and 90.3%, respectively. However, the presence of CTCs was not associated with any clinicopathologic features such as staging, histologic type, or mucin phenotype. [Conclusion] Although we could not prove the clinical feasibility of CTCs for gastric cancer staging, our results suggest a potential role of CTCs as an early diagnostic biomarker of gastric cancer

Balloon dilatation angioplasty of stenosed systemic - pulmonary artery shunts

Seven children and an adult patient with cyanotic congenital heart defects underwent balloon dilatation angioplasty (BDA) of a stenosed systemic-pulmonary artery shunt to improve arterial oxygen saturation. We attempted to perform BDA using the transvenous route in all patients in whom the aorta connected with the right ventricle, such as in tetralogy of Fallot or double outlet right ventricle, in an effort to avoid femoral artery injury. We could use the transvenous route (antegrade) in three children with tetralogy of Fallot and in one child with tetralogy of Fallot and pulmonary atresia (one of them was 6.6 kg). Fallowing BDA, there was an increase in arterial oxygen saturation from a mean of 65.9 +/- 12.8% to a mean of 78.1 +/- 8.3% (p < 0.05). On follow-up three to 37 months (mean 16.5 +/- 11.2 months) after BDA, the condition of all patients had improved. Pulmonary hypertension developed in one patient during the follow-up period. It is concluded that BDA of stenosed systemic-pulmonary artery shunts is reasonable, effective and safe. Use of the transvenous route, if possible, to perform balloon dilatation angioplasty facilitates the safe advancement of the larger balloons in low-weight children