Characterisation of abrasive water-jet process for pocket milling in Inconel 718

Experiments were carried out in Inconel 718 in order to investigate the possibility of using the abrasive water-jet process for producing 3D features such as pockets. A design of experiments approach was taken, considering variables such as water pressure, nozzle stand-off distance, traverse speed, nozzle orifice diameter, abrasive mass flow rate and tool-path step over distance. The experimental variables were related to depth of cut and pocket geometry. Statistical analysis was carried out in order to develop mathematical models which include process variable interactions and quadratic terms. This led to models with high correlation and prediction power which allow a better understanding of the process and can form the base for further process optimisation. The models were validated with additional experiments and showed good agreement with the water-jet system. The results showed that water pressure has a non-linear behaviour and is of paramount importance for controlling the depth of cut and geometrical errors. Additionally, nozzle diameter and the interaction between feed rate and abrasive mass flow are critical factors affecting the depth of cut

Advanced surface characterization of silver nanocluster segregation in Ag-TiCN bioactive coatings by RBS, GDOES and ARXPS

Surface modification by means of wear protective and antibacterial coatings represents, nowadays, a crucial challenge in the biomaterials field in order to enhance the lifetime of bio-devices. It is possible to tailor the properties of the material by using an appropriate combination of high wear resistance (e.g., nitride or carbide coatings) and biocide agents (e.g., noble metals as silver) to fulfill its final application. This behavior is controlled at last by the outmost surface of the coating. Therefore, the analytical characterization of these new materials requires high-resolution analytical techniques able to provide information about surface and depth composition down to the nanometric level. Among these techniques are Rutherford backscattering spectrometry (RBS), glow discharge optical emission spectroscopy (GDOES), and angle resolved X-ray photoelectron spectroscopy (ARXPS). In this work, we present a comparative RBS–GDOES–ARXPS study of the surface characterization of Ag–TiCN coatings with Ag/Ti atomic ratios varying from 0 to 1.49, deposited at room temperature and 200 °C. RBS analysis allowed a precise quantification of the silver content along the coating with a non-uniform Ag depth distribution for the samples with higher Ag content. GDOES surface profiling revealed that the samples with higher Ag content as well as the samples deposited at 200 °C showed an ultrathin (1–10 nm) Ag-rich layer on the coating surface followed by a silver depletion zone (20–30 nm), being the thickness of both layers enhanced with Ag content and deposition temperature. ARXPS analysis confirmed these observations after applying general algorithm involving regularization in addition to singular value decomposition techniques to obtain the concentration depth profiles. Finally, ARXPS measurements were used to provide further information on the surface morphology of the samples obtaining an excellent agreement with SEM observations when a growth model of silver islands with a height d = 1.5 nm and coverage θ = 0.20 was applied to the sample with Ag/Ti = 1.49 and deposited at room temperature.This work was financially supported by the Spanish Ministry of Science and Innovation (projects FUNCOAT CSD2008-00023 and RyC2007-0026). This research is sponsored by FEDER funds through the program COMPETE "Programa Operacional Factores de Competitividade" and by national funds through FCT "Fundacao para a Ciencia e a Tecnologia", in the framework of the Strategic Projects PEST-C/FIS/UI607/2011, and PEST-C/EME/UI0285/2011 and under the project PTDC/CTM/102853/2008. The authors would like to acknowledge I. Caretti and R. Velasco for the fruitful discussions and the proofreading of the manuscript

Breast papillomas: current management with a focus on a new diagnostic and therapeutic modality

Breast papilloma is a term that describes an intraductal papillary configuration of the mammary epithelium on macroscopic or microscopic examination. It includes solitary intraductal papillomas, multiple papillomas, papillomatosis, and juvenile papillomatosis (JP). Recent advances in mammary ductoscopy (MD) have raised new possibilities in the diagnosis and treatment of breast papillomas. This technique represents an important diagnostic adjunct in patients with pathological nipple discharge (PND) by allowing direct visualisation and biopsy of intraductal lesions and guiding duct excision surgery. Treatment of breast papillomas often entails surgical duct excision for symptomatic relief and histopathological examination. Recently, more conservative approach has been adapted. MD-assisted microdochectomy should be considered the procedure of choice for a papilloma-related single duct discharge. Furthermore, there is increasing evidence that MD has the potential to reduce the number of duct excision procedures and minimise the extent of surgical resection. Imaging-guided vacuum-assisted core biopsy can be diagnostic and therapeutic for papillomas seen on mammography and/or ultrasound. Patients with multiple papillomas do have an increased risk of developing cancer and should be kept under annual review with regular mammography (preferably digital mammography) if treated conservatively. Magnetic resonance (MR) can be also used in surveillance in view of its high sensitivity. Because the risk is small, long term and affects both breasts, long-term follow-up is more appropriate than prophylactic mastectomy. Patients who prove to have solitary duct papilloma have insufficient increase in the risk of subsequent malignancy to justify routine follow-up

Culturally relevant social work services for latinas infected or affected with HIV/AIDS.

As we begin the third decade of the HIV/AIDS pandemic, concerns continue about social, psychological, and behavioral aspects of the living with the illness. What was once thought to be predominately a gay, Anglo disease has now become prominent in the heterosexual population crossing all racial and class lines. Presumed injection drug users have always been highly infected. However, studies show that HIV/AIDS is affecting different populations at shockingly disproportionate rates. The HIV/AIDS pandemic in the United States is disproportionately represented and is growing at a faster rate in ethnic minority communities as compared to majority populations (Centers for Disease Control and Prevention [CDC], 2002). The purpose of this article is to explore the specific issues associated with HIV/AIDS in racial and ethnic minorities, with a specific focus on how the increase of new AIDS cases is affecting Latinas. Disparities such as lack of access to medical care and unique socio-cultural issues are discussed, followed by implications for social work practice, policy, research, and education

Constraints on singlet right-handed neutrinos coming from the Z0Z^0-width

We study the constraints on masses and mixing angles imposed by the measured $Z^0$ invisible width, in a model in which a singlet right-handed neutrino mixes with all the Standard Model neutrinos.Comment: Revtex, 7 pages, two figures available from the authors, preprint IFT-P.040/92 IFUSP/P-1023/9

Characterisation of abrasive water-jet process for drilling titanium and carbon fibre reinforced polymer stacks

Experiments were carried out in stacks composed of titanium and carbon-fibre-reinforced polymer (CFRP) with the aim to investigate the effect of water-jet process variables on drilled diameter and surface condition. A design of experiments (DoE) approach was taken, considering variables such as water pressure, traverse rate, abrasive mass flow and stack set-up. Two different set-ups were investigated: CFRP over titanium (CFRP/Ti) and vice versa (Ti/CFRP). The experimental variables were related to taper ratio, surface roughness of the hole bore, hole quality and surface condition. Statistical analysis was carried out in order to develop mathematical models which include process variables interactions and quadratic terms. This led to models with high correlation and prediction power; which allow a better understanding of the process and can form the base for further process optimisation. The models were validated with additional experiments and showed good agreement with the water-jet system. The results showed that set-up and its interaction with other process variables has a strong influence on the performance of the abrasive water-jet system for producing holes in hybrid materials

Nonlinear Meissner effect in a high-temperature superconductor: Local versus nonlocal electrodynamics

Measured intermodulation distortion (IMD) power at 1.5 GHz in a series of YBa[subscript 2]Y[subscript 3]O[subscript 7−δ] stripline resonators of varying strip widths is compared to the predictions of two qualitatively distinct theories of the nonlinear Meissner effect. The stripline resonators are patterned from a single wafer to ensure uniformity of the material properties. According to the first theory [T. Dahm and D. J. Scalapino, Phys. Rev. B 60, 13125 (1999)], the IMD power is dominated by contributions from the strip edges, while according to the second theory [D. Agassi and D. E. Oates, Phys. Rev. B 72, 014538 (2005)] it is dominated by contributions from the body of the strip. The parameter-free comparison of the measured data with the theoretical predictions clearly favors the latter theory. We conclude that the nonlinear component of the penetration depth must be treated with nonlocal electrodynamics. The origins of this outcome are discussed briefly in the framework of a Green’s-function approach