0.8 μW 12-bit SAR ADC sensors interface for RFID applications

The design and first measuring results of an ultra-low power 12 bit successive-approximation ADC for autonomous multi-sensor systems are presented. The comparator and the DAC are optmised for low power consumption. The power consumption is 0.52 μW from a 1.2 V supply with a sample clock of 3.125 kHz and 0.85 μW at 6.25 kHz. This gives 136 pJ per conversion or 66 fJ per conversion step. As per authors’ knowledge, 66 fJ per conversion step is the best reported so far.The ADC was realised in the NXP CMOS 0.14 μm technology; the area was 0.35 mm². Only four metal layers were used in order to allow 3D integration of the sensors.     

Perceptual audio data concealment and watermarking scheme using direct frequency domain substitution

A method is described for perceptually transparent data concealment and watermarking in audio. The proposed system replaces redundant and imperceptible frequency components with hidden data. A psychoacoustic model is used to identify suitable frequency locations for data hiding. Such a method is complicated by the windowing and overlapping requirements used for signal conditioning. The proposed system uses data flipping in place of windowing and incorporates a novel data detection scheme with adaptive weighting to increase the robustness of the watermark transmission. The resistance of the watermarking system to filtering, amplitude scaling and additive white noise is measured and results presented.     

Validation of the in vivo intravascular ultrasound measurement of in-stent neointimal hyperplasia volumes

OBJECTIVES: This study was undertaken to validate the in vivo intravascular ultrasound (IVUS) measurement of in-stent neointimal hyperplasia (IH) volumes. BACKGROUND: Because stents reduce restenosis compared to balloon angioplasty, stent use has increased significantly. As a result, in-stent restenosis is now an important clinical problem. Serial IVUS studies have shown that in-stent restenosis is secondary to intimal hyperplasia. To evaluate strategies to reduce in-stent restenosis, accurate measurement of in-stent neointimal tissue is important. METHODS: Using a porcine coronary artery model of in-stent restenosis, single Palmaz-Schatz stents were implanted into 16 animals with a stent:artery ratio of 1.3:1. Intravascular ultrasound imaging was performed at 1 month, immediately prior to animal sacrifice. In vivo IVUS and ex vivo histomorphometric measurements included stent, lumen and IH areas; IH volumes were calculated with Simpson's rule. RESULTS: Intravascular ultrasound measurements of IH (30.4+/-11.0 mm3) volumes correlated strongly with histomorphometric measurements (26.7+/-8.5 mm3, r=0.965, p < 0.0001). The difference between the IVUS and the histomorphometric measurements of IVUS volume was 4.1+/-2.7 mm3 or 15.8+/-11% (standard error of the estimate=0.7). Both histomorphometry and IVUS showed that IH was concentric and uniformly distributed over the length of the stent. Intravascular ultrasound detected neointimal thickening of < or =0.2 mm in 5 of 16 stents. Sample size calculations based on the IVUS measurement of IH volumes showed that 12 stented lesions/arm would be required to show a 50% reduction in IVUS-measured IH volume and 44 stented lesions/arm would be required to show a 25% reduction in IH volume. CONCLUSION: In vivo IVUS measurement of IH volumes correlated strongly with ex vivo histomorphometry. Using volumetric IVUS end points, small sample sizes should be necessary to demonstrate effectiveness of strategies to reduce in-stent restenosis.     

Structural transformation in Mn-substituted Sr2Bi2Ta2TiO12 Aurivillius phase synthesized by hydrothermal method: A comparative study and dielectric properties

In this study, a hydrothermal method was applied to synthesize the three-layer Aurivillius phase Sr₂Bi₂Ta₂TiO₁₂ (SBTTO) and Mn-substituted Sr_1·5Bi_2·5Ta₂Ti_0·5Mn_0·5O₁₂ (SBTTMO), with the use of NaOH as a mineralizer. The crystal structure, morphology, dielectric properties, and the correlation between the structural transformation and dielectric properties were investigated. The XRD data reveal that the SBTTO sample adopts a tetragonal crystal structure with the I4/mmm space group and is then transformed into an orthorhombic structure with the B2cb space group for SBTTMO. The morphology of both samples was observed by SEM, which showed anisotropic plate-like grains. With the Mn substitution, the ferroelectric transition temperature (T_c) significantly increases as the influence of the 6s² lone pair of Bi³⁺ increases, and this in turn further induces the relaxor-ferroelectric behavior. Consequently, the increase in T_c confirms the structural transformation from the paraelectric-tetragonal to the ferroelectric-orthorhombic phase.     

Functionally graded tricalcium phosphate/fluoroapatite composites

This study was conducted to prepare fluorine-substituted apatite (FA)/beta-tricalcium phosphate (β-TCP) composites to combine the biostability of FA with the bioresorbability of β-TCP. The FA was prepared for the first time by mixing hydroxyapatite (HA) with aluminium fluoride (coded as AF). On the other hand, the β-TCP was prepared from a mixture of HA and CaHPO₄ (calcium hydrogen phosphate). The dissolution behaviour of the composites was tested using a 10-wt.% citric acid solution. Scanning electron microscopy (SEM) indicated that β-TCP dissolved in the citric acid much faster than FA, resulting in macropores among the FA matrix. In addition to bulk FA/β-TCP composites, novel functionally gradient FA/β-TCP composites were also prepared by varying the particle size and the volume content of the β-TCP granules. The functionally gradient FA/β-TCP composites could be used to design implants.     

Peptide-Coated Vascular Grafts: An In Vivo Study in Sheep

Background: The purpose of this study was to evaluate the amount of neo‐intimal tissue in‐growth present at the arterial and venous sides of the anastomosis and the degree of endothelial cell lining of the graft lumen in sheep using commercial vascular grafts coated with the P15 cell‐binding peptide. Methods: ePTFE vascular grafts were coated with the cell‐binding P15 peptide using a newly developed plasma surface treatment method. 4 P15‐treated grafts and 2 control grafts were implanted as arterio‐venous fistulas between the femoral artery and vein and between the carotid artery and jugular vein in 2 sheep. 1 animal was euthanized after 14 days and the other animal after 28 days. The grafts along with the connecting arteries and veins were explanted and evaluated for the length of tissue in‐growth along the luminal surface of the ePTFE graft from the anastomosis at the arterial and venous sides. Intimal thickness was carefully measured. Scanning electronic microscopy (SEM) was used to confirm the endothelial cell lining. Results: The study showed a significant difference (p < 0.05) in intimal thickness between the coated and uncoated grafts in the venous side of the anastomosis. The average intimal thickness of coated samples (551 μm) was 3 times thinner than that of uncoated ones (1657 μm). The endothelial cell lining appeared to be thicker, and its coverage was more uniform for the peptide‐coated grafts than the uncoated ones. Overall, there was more neo‐intimal tissue in‐growth at the venous side than the arterial side of the anastomosis. The intima at the venous side was also thicker and more bulky compared to the arterial side. Conclusion: This study has demonstrated that P15‐coated ePTFE grafts had less intimal tissue in‐growth developed at the venous side of the anastomosis than the uncoated ePTFE grafts. The degree of endothelial cell lining for coated samples was also higher than uncoated ones, which is consistent with our in vitro studies using human umbilical vein endothelial cells. P15‐coated ePTFE graft materials had significantly improved cell adhesion, proliferation, and migration in vitro over uncoated ePTFE.      

14C]7-ethoxycoumarin metabolism by precision-cut rat hepatic slices

It is recognized that iodine-123-labelled 15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (123I-BMIPP) slowly washes out of the myocardium. The mechanism for the washout was investigated in normal rat hearts by analyses of the subcellular distribution and lipid classes based on the BMIPP metabolism. Rat hearts were excised at 1-120 min after intravenous injection of 123I-BMIPP. After counting the radioactivity, the hearts were digested with Nagarse and homogenized, and then fractionated into the cytosolic, mitochondrial, microsomal and crude nuclear fractions by centrifugations. The radioactivity of each fraction was counted, and the lipid classes were analysed by radio-thin-layer chromatographic and high-performance liquid chromatographic methods. The heart uptake of 123I-BMIPP was maximal at 5 min (6.81%+/-0.36% ID/g), and 41% of the radioactivity disappeared within 120 min. The myocardial radioactivity was immediately distributed into the cytosolic, mitochondrial, microsomal and crude nuclear fractions. The distribution (%) of each fraction was almost identical from 5 min through 120 min. The cytosolic fraction was always the major site of radioactivity deposition (60%), and the time-activity curve of the cytosolic fraction paralleled that of the whole heart throughout the 120-min study period. In the cytosolic fraction, most of the radioactivity was incorporated into the triglyceride class, and the rest was present in the free fatty acid, phospholipid (phosphatidylcholine) and diglyceride classes. In the mitochondrial fraction, the radioactivity was mostly incorporated into the phospholipid class (phosphatidylethanolamine), followed by free fatty acids. The final metabolite of 123I-BMIPP, 123I-p-iodophenylacetic acid (123I-PIPA), initially appeared in the mitochondrial fraction as early as 1 min, and subsequently in the cytosolic fraction at 5 min. Another intermediary metabolite, 123I-p-iodophenyldodecanoic acid (123I-PIPC12), was found only in the mitochondrial fraction after 5 min. In conclusion, the slow washout kinetics of 123I-BMIPP from the myocardium mainly reflects the turnover rate of the triglyceride pool in the cytosol. The BMIPP metabolism, i.e. initial alpha-oxidation followed by subsequent cycles of beta-oxidation, was confirmed in vivo. The participation of the mitochondria in the metabolism was also proven.     

Fetal alcohol exposure augments the blunting of tumor necrosis factor production in vitro resulting from in vivo priming with lipopolysaccharide in young adult male but not female rats

We previously reported altered responses of thymocytes and splenocytes to mitogen stimulation in fetal alcohol-exposed (FAE) male Sprague-Dawley rats. We also reported enhanced neuroendocrine responses to stressful stimuli in these animals. The experiments we describe herein aimed at testing whether young adult FAE rats manifest a notable dysregulation in the neuroendocrine-immune response to pathogen administration. We tested the effect of in vivo priming of the animal with a low dose of endotoxin [lipopolysaccharide (LPS), 5 micrograms/kg], considered to be suboptimal from the perspective of mounting detectable levels of circulating monokines several hours after administration, upon the production of immunoreactive tumor necrosis factor (TNF-alpha) in response to a further in vitro challenge of peripheral blood mononuclear cells with 2.5 micrograms/ml of LPS 90 min after priming. We show that the response to the LPS pathogen in vitro after priming is significantly blunted (p < 0.01) in male rats exposed prenatally to alcohol, compared with control male animals. FAE female rats and FAE ovariectomized female rats do not show significant differences in the priming response, compared with control animals. We also show that there is no correspondence between plasma corticosterone levels and TNF-alpha production after priming in any of the groups tested.     

Green synthesis of CuFe2O4 nanoparticles mediated by Morus alba L. leaf extract: Crystal structure,grain morphology,particle size,magnetic and catalytic properties in Mannich reaction

Copper ferrite (CuFe₂O₄) is one of the most popular ferrite spinel semiconductors due to its superparamagnetic properties. In this study, CuFe₂O₄ nanoparticles were successfully prepared through green synthesis mediated by Morus alba L. leaf extract. Secondary metabolites, such as alkaloids and saponins, in Morus alba L. leaf extract acted as a weak base provider and as a capping agent in the formation of CuFe₂O₄. The crystal structure, grain morphology, particle size, and magnetic properties of the nanoparticles were investigated. X-ray diffraction (XRD) data confirms the formation of the CuFe₂O₄ phase with a cubic Fd-3ms space group. The nanoparticles mediated by Morus alba L. have a spherical shape with distributed particle sizes at 20–70 nm. In the evaluation of stability, the nanoparticles agglomerate with a zeta potential value of ?21.7 mV and have a soft ferromagnetic nature with H_c, M_r, and M_s values of 175.44 Oe, 1.75 emu/g, and 14.16 emu/g, respectively. The catalytic ability of CuFe₂O₄ nanoparticles in the Mannich reaction showed good catalyst performance with a yield of 83.83% at optimum conditions. Green synthesis using Morus alba L. leaf extract offers a more environmentally friendly and effective method for obtaining CuFe₂O₄ nanoparticles with good characteristics.