Mechanical and Tribological Behavior of Mechanically Alloyed Ni-TiC Composites Processed via Spark Plasma Sintering

Titanium carbide (TiC) reinforced nickel (Ni) matrix composites were processed via mechanical alloying (MA) followed by spark plasma sintering (SPS) process. Mechanical alloying has gained special attention as a powerful non-equilibrium process for fabricating amorphous and nanocrystalline materials, whereas spark plasma sintering (SPS) is a unique technique for processing dense and near net shape bulk alloys with homogenous microstructure. TiC reinforcement varied from 5 to 50 wt.% into nickel matrix to investigate its effect on the microstructure and mechanical behavior of Ni-TiC composites. All Ni-TiC composites powder was mechanically alloyed using planetary high energy ball mill with 400 rpm and ball to powder ratio (BPR) 15:1 for 24 h. Bulk Ni-TiC composites were then sintered via SPS process at 50 MPa pressure and 900–1200 °C temperature. All Ni-TiC composites exhibited higher microhardness and compressive strength than pure nickel due to the presence of homogeneously distributed TiC particles within the nickel matrix, matrix grain refinement, and excellent interfacial bonding between nickel and TiC reinforcement. There is an increase in Ni-TiC composites microhardness with an increase in TiC reinforcement from 5 to 50 wt.%, and it reaches the maximum value of 900 HV for Ni-50TiC composites.     

Development of starch based intelligent films by incorporating anthocyanins of butterfly pea flower and TiO2 and their applicability as freshness sensors for prawns during storage

Intelligent pH sensitive starch films were developed by incorporation of anthocyanin pigment extracted from butterfly pea flower (BPE) and nanosized TiO₂ using the method of solution casting. This research work evaluated the influence of BPE and TiO₂ on the physical and structural properties of starch films. The physical properties of the starch films could be significantly altered by the addition of BPE and or TiO₂. The starch films S/BPE and S/BPE/TiO₂ exhibited higher barrier properties against water vapour as compared to the control films. Incorporation of BPE and TiO₂ could decrease the thickness and moisture content of films. S, S/BPE starch films were transparent and, S/TiO₂ and S/BPE/TiO₂ films were opaque. Control starch films were colourless, whereas S/BPE films have purple colour. Owing to the inclusion of BPE and TiO₂ particles, structural characterization by X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) did not show any major changes in polymer structure. Thermogravimetric analysis revealed that the addition of TiO₂ enhanced the thermal stability of starch films to a significant extent. The color of different starch-based films was determined using the CIE Lab scale under different pH conditions and compared with the control. The fabricated (S/BPE and S/BPE/TiO₂) films exhibited visually perceptible colour changes in the pH range between 1 and 12. Consequently these films could be used as intelligent pH indicators for monitoring the freshness of prawn seafood samples. During the storage of prawn food samples for 6 days, the color of the film changed from light pink to green which is a clear indication of spoilage of food material.

Anthocyanin extracted from butterfly pea flower incorporated starch/TiO₂ films are excellent pH indicator for monitoring the freshness of food sample.     

Normal saline-induced deoxygenation of red blood cells probed by optical tweezers combined with the micro-Raman technique

The use of normal saline for washing red blood cells and treating critically ill patients is a regular medical practice in hospital settings. An optical tweezer in combination with Raman spectroscopy is an analytical tool employed for the investigation of single cell dynamics, thus providing molecular fingerprint of the cell by optically trapping the cell at a laser focus. In this study, the impact of normal saline on individual human red blood cell was compared with that of blood plasma using Raman tweezers spectroscopy. Major spectral variations in the marker frequencies at 1209 cm⁻¹, 1222 cm⁻¹, 1544 cm⁻¹, and 1561 cm⁻¹ of the Raman spectrum of the treated cells imply that the transition of hemoglobin to the deoxygenated state occurs when 0.9% normal saline is used. This may result in serious implications in blood transfusion. The results obtained from the principal component analysis also displayed clear differentiation among the red blood cells diluted in normal saline and those diluted in plasma. In future studies, efforts will be made to correlate the deoxygenation status of red blood cells with various human disorders.

Micro-Raman spectroscopy of optically trapped live red blood cell demonstrates normal saline induced deoxygenation.     

Radiation dose and image quality of X-ray volume imaging systems: cone-beam computed tomography, digital subtraction angiography and digital fluoroscopy

Objective

Radiation dose and image quality estimation of three X-ray volume imaging (XVI) systems.

Methods

A total of 126 patients were examined using three XVI systems (groups 1–3) and their data were retrospectively analysed from 2007 to 2012. Each group consisted of 42 patients and each patient was examined using cone-beam computed tomography (CBCT), digital subtraction angiography (DSA) and digital fluoroscopy (DF). Dose parameters such as dose–area product (DAP), skin entry dose (SED) and image quality parameters such as Hounsfield unit (HU), noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were estimated and compared using appropriate statistical tests.

Results

Mean DAP and SED were lower in recent XVI than its previous counterparts in CBCT, DSA and DF. HU of all measured locations was non-significant between the groups except the hepatic artery. Noise showed significant difference among groups (P?<?0.05). Regarding CNR and SNR, the recent XVI showed a higher and significant difference compared to its previous versions. Qualitatively, CBCT showed significance between versions unlike the DSA and DF which showed non-significance.

Conclusion

A reduction of radiation dose was obtained for the recent-generation XVI system in CBCT, DSA and DF. Image noise was significantly lower; SNR and CNR were higher than in previous versions. The technological advancements and the reduction in the number of frames led to a significant dose reduction and improved image quality with the recent-generation XVI system.

Key Points

? X-ray volume imaging (XVI) systems are increasingly used for interventional radiological procedures. ? More modern XVI systems use lower radiation doses compared with earlier counterparts. ? Furthermore more modern XVI systems provide higher image quality. ? Technological advances reduce radiation dose and improve image quality.     

Ultrafast cone-beam computed tomography imaging and postprocessing data during image-guided therapeutic practice

Objective

Our objective was to evaluate ultrafast cone-beam computed tomography (u-CBCT) image data using cross-sectional images, perfusion blood volume (PBV), and image fusion during tumour detection at the course of transarterial chemoembolization.

Methods

One hundred and fifty patients (63?±?20 years; 33–82) were examined from February to October 2013 with u-CBCT. Tumour delineation and conspicuity were determined using u-CBCT cross-sectional PBV and u-CBCT-magnetic resonance imaging (MRI) fused data sets for hyperenhanced (HYET), heterogeneously enhanced (HEET), and unenhanced (UET) tumour categories. Catheter localisation and tumour feeding vessels were assessed using all data sets. Quantitative and qualitative analyses were performed using appropriate statistical tests.

Result

Qualitative and quantitative tumour delineation showed significant difference (all P?P?P?Conclusion Tumour delineation was clearly possible using u-CBCT cross sections with contrast material. PBV uses color-coded images to increase detection and produces good tumour differentiation. Image fusion helps accurately identify tumour and feeding vessels and locate contrast material injection sites and catheter tips without additional data acquisition.

Key points

? Ultrafast CBCT cross-sectional data provide good tumour delineation with contrast material ? Postprocessed PBV using u-CBCT increased detectability and tumour differentiation ? u-CBCT cross-sectional PBV and u-CBCT-MRI data helps image guidance during chemoembolization ? u-CBCT-MRI can identify tumours and feeding vessels and locate catheter tip accurately     

ERCP in acute pancreatitis

BACKGROUND: The role of endoscopic retrograde cholangiopancreatography (ERCP) in the management of acute pancreatitis has evolved over years since its introduction in 1968. Its importance in diagnosing the etiology of pancreatitis has steadily declined with the advent of less invasive diagnostic tools. The therapeutic implications of ERCP in acute pancreatitis are many fold and are directed towards management of known etiological factors or its related complications. This article highlights the current status of ERCP in acute pancreatitis. DATA SOURCES: An English literature search using PubMed database was conducted on ERCP in acute pancreatitis, the etiologies and complications of pancreatitis amenable to endotherapy and other related subjects, which were reviewed. RESULTS: ERCP serves as a primary therapeutic modality for management of biliary pancreatitis in specific situations, pancreatitis due to microlithiasis, specific types of sphincter of Oddi dysfunction, pancreas divisum, ascariasis and malignancy. In recurrent acute pancreatitis and smoldering pancreatitis it has a definite therapeutic utility. Complications of acute pancreatitis including pancreatic-duct disruptions or leaks, benign pancreatic-fluid collections and pancreatic necrosis can be beneficially dealt with. Intraductal ultrasound and pancreatoscopy during ERCP are useful in detecting pancreatic malignancy. CONCLUSIONS: The role of ERCP in acute pancreatitis is predominantly therapeutic and occasionally diagnostic. Its role in the management continues to evolve and advanced invasive procedures should be undertaken only in centers dedicated to pancreatic care.     

Distinguishing Tuberculosis and Crohn's Disease in Developing Countries: How Certain Can You Be of the Diagnosis?

Distinguishing tuberculosis and Crohn''s disease in patients presenting with chronic abdominal pain and diarrhea is a huge diagnostic challenge, particularly in tuberculosis endemic countries. A large number of patients with Crohn''s disease are initially misclassified as having Intestinal tuberculosis in places where tuberculosis is endemic before they are treated for Crohn''s disease. Although a variety of endoscopic, radiological and histological criteria have been recommended for the differentiation, it often proves difficult in routine clinical practice. Future prospective studies are required in patients with granulomatous colitis to prevent unnecessary inappropriate anti tuberculous therapy for patients with Crohn''s disease and appropriate early treatment for a patient with tuberculosis.     

Laser Raman tweezer spectroscopy to explore the bisphenol A-induced changes in human erythrocytes

The dermal penetration of bisphenol-A (BPA) from thermal papers into the human skin is a matter of major health concern due to its extensive use in developing countries like India, one of its largest users in the world. Bisphenol A is widely used in the manufacture of many consumer goods like polycarbonate water bottles, baby bottles, food containers, home appliances, thermal papers used in billing and tickets, the inner lining of food cans, etc. BPA can be easily adsorbed into the blood rapidly. The integration of optical tweezers with Raman spectroscopic techniques has realized avenues for interpreting single cell investigations. In the present work, the impact of BPA from thermal papers on individual human erythrocytes (red blood cells) has been investigated using micro-Raman spectroscopy. Significant intensity variations were noticed for hemoglobin oxygenation markers in the Raman spectra of red blood cells (RBCs). Raman spectral variations supporting RBC hemoglobin depletion were also found in the presence of BPA. Evident morphological changes are also observed in RBCs due to BPA in vitro exposures, which ultimately lead to cell bursting at higher concentrations.

Hemoglobin depletion was observed at higher BPA concentration.