A single crystal row-column-array for 3D ultrasound imaging.

In vivo 3D ultrasound imaging with 2D-array transducers is of great importance for both clinical application and biomedical research, but it is complicated in fabrication and also very expensive in hardware due to thousands of electronic channels. In this work, we demonstrate a new fabrication process of 7-MHz 128 + 128 elements row-column-array (RCA) transducer with relaxor ferroelectric PMN-0.28PT single crystal. With piezoelectric single crystal and improved acoustic matching, the optimized performance of -6 dB bandwidth of ∼82 % and insertion loss of -44.6 dB is achieved. The axial and lateral imaging resolutions at different depth of the RCA transducer are quantified by the point spread function (PSF), and the results are respectively 0.20 mm and 0.41 mm at the depth of 7.7 mm, and 0.22 mm and 0.47 mm at the depth of 16.7 mm. The transducer is validated experimentally on a hyperechoic phantom, and 3D view and slices of B-mode images are obtained. The experimental results indicate that our developed RCA transducer can obtain high-quality 3D ultrasound images, demonstrating great potential on ultrafast 3D and functional imaging.

Guiding infrared electromagnetic waves through TI nanowires with extremely large wavenumber and azimuthal index.

In this paper, the dispersion relations of the surface plasmon polaritons (SPPs) in TI nanowires have been investigated. For simplicity, TI nanowire has been modeled as a dielectric cylinder with a conductive surface, the conductivity of which is an anti-symmetric tensor. The off-diagonal terms of the conductivity tensor only slightly change the dispersion relations. Due to small conductivities, these SPPs have extremely large wavenumbers and azimuthal indices; the electric fields are tightly confined near the conductive surface. For high-order modes, cut-off phenomena have been observed. In the end, the effects of losses and much larger bulk permittivities on the dispersion relations of surface plasmons have been discussed. The simple model proposed in this paper can be directly applied to other materials with arbitrary surface conductivity. Our investigations show that TI nanostructures are promising platforms for nanophotonic applications in the future.

Symmetry groupoids for pattern-selective feedback stabilization of the Chafee-Infante equation.

Reaction-diffusion equations are ubiquitous in various scientific domains and their patterns represent a fascinating area of investigation. However, many of these patterns are unstable and, therefore, challenging to observe. To overcome this limitation, we present new noninvasive feedback controls based on symmetry groupoids. As a concrete example, we employ these controls to selectively stabilize unstable equilibria of the Chafee-Infante equation under Dirichlet boundary conditions on the interval. Unlike conventional reflection-based control schemes, our approach incorporates additional symmetries that enable us to design new convolution controls for stabilization. By demonstrating the efficacy of our method, we provide a new tool for investigating and controlling systems with unstable patterns, with potential implications for a wide range of scientific disciplines.

20-MHz phased array ultrasound transducer for in vivo ultrasound imaging of small animals.

In vivo ultrasound imaging with phased array transducers is of great importance for both clinical application and biomedical research. In this work, relaxor ferroelectric PMN-0.28PT single crystal with very high piezoelectric constant d33 ≥ 2000 pC/N and electromechanical coupling coefficient k33 âˆ¼ 0.92 is used to fabricate high-frequency phased array transducers. A 128-element 20-MHz phased array transducer is successfully fabricated, and the optimized performance of -6 dB average bandwidth of âˆ¼ 84 % and insertion loss of -43 dB are achieved. The axial and lateral imaging resolutions of the transducer are determined to be 81 µm and 243 µm, respectively. With Verasonics image platform, in vivo fisheye images are acquired, demonstrating the potential application of our developed high-frequency phased array transducer for biomedical research on small animals.

[The 492nd case: recurrent thrombosis, thrombocytopenia].

A 43-year-old female patient was admitted with recurrent thrombosis for more than 2 years and thrombocytopenia for more than 1 year. Both arterial and venous thromboses developed especially at rare sites even during anticoagulation therapy such as cerebral venous sinus thrombosis. Antinuclear antibody, anti-ENA antibody and antiphospholipid antibody were all negative. Platelet count elevated to normal after high dose glucocorticoid and intravenous immunoglobulin (IVIG). Immune thrombocytopenia was suspected. When 4 grade thrombocytopenia recurred, intravenous heparin, rituximab 600 mg, IVIG and eltrombopag were administrated. After 3 weeks, thrombocytopenia did not improve, and new thrombosis developed instead. Screening of thrombophilia related genes revealed PROS1 gene heterozygous mutation and MTHFR TT genotype. Low amount of serum IgG κ monoclonal protein was detected. Heparin-induced thrombocytopenia was differentiated and excluded. Finally, serum negative antiphospholipid syndrome was considered the most likely diagnosis. Dexamethasone 20 mg/day × 4 days combined with sirolimus 2 mg/day was prescribed. The patient was discharged with low molecular weight heparin. At one month, her headache was greatly relieved. The platelet count raised to 20-30×109/L, and no new thrombosis or bleeding was reported.

[Effect of Sunitinib therapy on immune function of patients with advanced renal cell carcinoma].

Objective: To evaluate the effect of Sunitinib therapy on immune function of patient with advanced renal cell carcinoma. Methods: A total of 27 patient with advanced renal cell carcinoma who received Sunitinib therapy in Chongqing Cancer Hospital from July 2010 to July 2014 were recruited in a prospective cohort study.Nineteen were male patients and 8 were female patients aged from 36 to 75 years with mean age of (58±7)years.Twenty-five cases were renal clear cell carcinoma, the other two cases were papillary renal cell carcinoma and Xp11.2 translocation renal cell carcinoma.According to MSKCC terminal prognosis scoring recommend by NCCN: 22 cases were in low risk, 5 cases were in high risk.All the patient took Sunitinib 50 mg orally once daily for 4 weeks, followed-up by 2 weeks.Flow cytometry was used to detect the levels of CD3+ , CD8+ , CD4+ T lymphocyte, NK cell and B lymphocyte in peripheral blood of patients before taking medicine.The levels of CD3+ , CD8+ , CD4+ T lymphocyte, NK cell, B lymphocyte in peripheral blood were detected again after 4 weeks, 6 weeks, 10 weeks and the disease progression.Paired t-test was used to analyze the data comparison of two groups, mean comparison in groups was conducted with repeated measurements analysis of variance, and the pairwise comparison was performed with LSD-t method. Results: The levels of CD3+ , CD8+ T lymphocyte, NK cell, B lymphocyte were significantly increased after the therapy of Sunitinib for 1 cycle(I-J was 212±22, 163±18, 59±12, 13.8±1.4, respectively, all P<0.05). The levels of CD3+ , CD8+ T lymphocyte, NK cell, B lymphocyte were significantly increased after the therapy of Sunitinib for 2 cycles(I-J was 362±43, 299±28, 91±19, 28.1±3.9, respectively, all P<0.05), while the level of CD4+ lymphocyte was decreased, but no significant difference(F=0.873, P>0.05). CD4+ /CD8+ was significantly decreased after the therapy of Sunitinib for 1 cycle, and it went on decreasing after the therapy of Sunitinib for 2 cycles(I-J was -0.31±0.03, -0.44±0.04, respectively, all P<0.05). Disease progression occurred in 10 cases during the follow-up period.The NK cell, CD3+ , CD4+ , CD8+ T lymphocyte were significantly decreased when the disease progressed(t=2.39-5.769, all P<0.05). Conclusions: Sunitinib has effect on the immune function of patients with advanced renal cell carcinoma, and the progression of renal cell carcinoma is related to the immune function.It suggests that targeted drug therapy should be combined with biological immunotherapy, which may be the research direction for the treatment of advanced renal cell carcinoma.

Anodic aluminum oxide-epoxy composite acoustic matching layers for ultrasonic transducer application.

The goal of this work is to demonstrate the application of anodic aluminum oxide (AAO) template as matching layer of ultrasonic transducer. Quarter-wavelength acoustic matching layer is known as a vital component in medical ultrasonic transducers to compensate the acoustic impedance mismatch between piezoelectric element and human body. The AAO matching layer is made of anodic aluminum oxide template filled with epoxy resin, i.e. AAO-epoxy 1-3 composite. Using this composite as the first matching layer, a ∼12MHz ultrasonic transducer based on soft lead zirconate titanate piezoelectric ceramic is fabricated, and pulse-echo measurements show that the transducer exhibits very good performance with broad bandwidth of 68% (-6dB) and two-way insertion loss of -22.7dB. Wire phantom ultrasonic image is also used to evaluate the transducer's performance, and the results confirm the process feasibility and merit of AAO-epoxy composite as a new matching material for ultrasonic transducer application. This matching scheme provides a solution to address the problems existing in the conventional 0-3 composite matching layer and suggests another useful application of AAO template.

Low-field Switching Four-state Nonvolatile Memory Based on Multiferroic Tunnel Junctions.

Multiferroic tunneling junction based four-state non-volatile memories are very promising for future memory industry since this kind of memories hold the advantages of not only the higher density by scaling down memory cell but also the function of magnetically written and electrically reading. In this work, we demonstrate a success of this four-state memory in a material system of NiFe/BaTiO3/La0.7Sr0.3MnO3 with improved memory characteristics such as lower switching field and larger tunneling magnetoresistance (TMR). Ferroelectric switching induced resistive change memory with OFF/ON ratio of 16 and 0.3% TMR effect have been achieved in this multiferroic tunneling structure.

Focused intravascular ultrasonic probe using dimpled transducer elements.

High-frequency focused intravascular ultrasonic probes were fabricated in this study using dimple technique based on PMN-PT single crystal and lead-free KNN-KBT-Mn ceramic. The center frequency, bandwidth, and insertion loss of the PMN-PT transducer were 34 MHz, 75%, and 22.9 dB, respectively. For the lead-free probe, the center frequency, bandwidth, and insertion loss were found to be 40 MHz, 72%, and 28.8 dB, respectively. The ultrasonic images of wire phantom and vessels with good resolution were obtained to evaluate the transducer performance. The -6 dB axial and lateral resolutions of the PMN-PT probe were determined to be 58 µm and 131 µm, respectively. For the lead-free probe, the axial and lateral resolutions were found to be 44 µm and 125 µm, respectively. These results suggest that the mechanical dimpling technique has good potential in preparing focused transducers for intravascular ultrasound applications.

Body mass index, waist-to-hip ratio, waist circumference and waist-to-height ratio cannot predict male semen quality: a report of 1231 subfertile Chinese men.

There were controversial results between obesity-associated markers and semen quality. In this study, we investigated the correlations between age, obesity-associated markers including body mass index (BMI), waist-to-hip ratio (WHR), waist-to-height ratio (WHtR) and waist circumference (WC), the combination of age and obesity-associated markers, semen parameters and serum reproductive hormone levels in 1231 subfertile men. The results showed that BMI, WC, WHR and WHtR were positively related to age, and there were also positive relations between BMI, WHR, WC and WHtR and between sperm concentration (SC), total sperm count (TSC), progressive motility (PR), sperm motility and per cent of normal sperm morphology (NSM). However, age, each of obesity-associated markers and the combination of obesity-associated markers and age were unrelated to any of semen parameters including total normal-progressively motile sperm count (TNPMS). Age, BMI, WHR, WC and WHtR were negatively related to serum testosterone and SHBG levels. However, only serum LH and FSH levels were negatively related to sperm concentration, NSM and sperm motility. In a conclusion, although age and obesity have significant impacts on reproductive hormones such as testosterone, SHBG and oestradiol, semen parameters related to FSH and LH could not be influenced, indicating that obesity-associated markers could not predict male semen quality.

High frequency PMN-PT single crystal focusing transducer fabricated by a mechanical dimpling technique.

High frequency (∼30MHz and ∼80MHz) focusing ultrasound transducers were fabricated using a PMN-0.28PT single crystal by a mechanical dimpling technique. The dimpled single crystal was used as an active element for the focusing transducer. Compared with a plane transducer, the focusing transducer fabricated with a dimpled active element exhibits much broader bandwidth and higher sensitivity. Besides, a high quality image can be obtained by the 30MHz focusing transducer, in which the -6dB axial and lateral resolution is 27µm and 139µm, respectively. These results prove that the dimpling technique is capable to fabricate the high frequency focusing transducers with excellent performance for imaging applications.

Bandwidth improvement of LiNbO3 ultrasonic transducers by half-concaved inversion layer approach.

A novel type of half-concaved LiNbO(3) plate with domain inversion layer has been proposed for fabricating high-frequency broadband ultrasonic transducers. Two opposite ferroelectric polarization layers with a curved boundary are presented after heat treatment in the half-concaved LiNbO(3) plate with a total thickness of 110 µm. Characterization of the transducers illustrates that, without a matching layer, the self-focusing transducer with the half-concaved LiNbO(3) plate has achieved 123% bandwidth at the center frequency of 60 MHz, which is a significant improvement over the planar inversion layer transducer.

Influence of discharge gap on the discharge stability in a short vacuum arc ion source.

The influence of the discharge gap between cathode and anode on the discharge stability in a short vacuum arc (SVA) ion source is presented in this paper. Planar cathode and cylindrical hollow anode made of titanium are investigated. There is a great need in present accelerator injection research for SVA source to produce the small deviation of the ion current beam. Current research shows that increasing the short discharge gap can reduce the level of ion current deviation and ion charge deviation from 29% and 31% to 15% and 17%, respectively. A microplasma plume generation mechanism in SVA and scanning electron microscopic results can be used to explain this interesting phenomenon.

PMN-PT single crystal focusing transducer fabricated using a mechanical dimpling technique.

A ∼5MHz focusing PMN-PT single crystal ultrasound transducer has been fabricated utilizing a mechanical dimpling technique, where the dimpled crystal wafer was used as an active element of the focusing transducer. For the dimpled focusing transducer, the effective electromechanical coupling coefficient was enhanced significantly from 0.42 to 0.56. The dimpled transducer also yields a -6dB bandwidth of 63.5% which is almost double the bandwidth of the plane transducer. An insertion loss of the dimpled transducer (-18.1dB) is much lower than that of the plane transducer. Finite element simulation also reveals specific focused beam from concave crystal surface. These promising results show that the dimpling technique can be used to develop high-resolution focusing single crystal transducers.

Effect of strain on ferroelectric and magnetic behavior in Pb(Zr0.52Ti0.48)O3-based magnetoelectric heterostructures.

In this paper, the "sandwich" structured magnetoelectric composite films of Pb(Zr0.52Ti0.48)O3/ NiFe2O4/Pb(Zr0.52Ti0.48)O3 and Pb(Zr0.52Ti0.48)O3/CoFe2O4/Pb(Zr0.52Ti0.48)O3 are epitaxially grown on SrRuO3/SrTiO3 substrates by pulsed-laser deposition. The crystalline quality and microstructures of these heterostructures are investigated by X-ray diffraction technique. The effects of strain on the ferroelectric, magnetic and magnetoelectric coupling properties of these thin films are systematically studied. The results show that the strain effect induced by lattice mismatch between the ferroelectric/ferromagnetic layers plays an important role in the ferroelectric and magnetic properties of these composite films. Compared to the strained Pb(Zr0.52Ti0.48)O3/ CoFe2O4/Pb(Zr0.52Ti0.48)O3 heterostructure, improved ferroelectric properties with an out-of-plane polarization (2P(r)) of 34.2 microC/cm2 and electric coercivity field of 158 kV/cm are obtained in the strain-free Pb(Zr0.52Ti0.48)O3/NiFe2O4/Pb(Zr0.52Ti0.48)O3 heterostructure. The ME measurement results not only show that the strain induced by lattice mismatch has great influence on the ME behavior, but also provide an understanding of the multilayers with full control over the interface structure at the atomic-scale.

Memory effect of an organic based trilayer structure with Au nanocrystals in an insulating polymer matrix.

The memory effects of gold (Au) nanocrystal (NC) non-volatile memory structures consisting of polyvinylpyrrolidone (PVP) K-30 polymer tunneling and control layers are investigated. The trilayer structure (PV P/Au-NCs + PV P/PV P) on p-type Si substrate was fabricated by spin coating, and transmission electron microscopy study reveals that the average size of the Au-NCs formed is about 5 nm in diameter. Capacitance-voltage (C-V) measurement on the memory structure shows a counter-clockwise hysteresis loop with a significant flat band voltage shift, revealing a memory effect of the Au-NCs with a charge density of up to 1 x 10(12) cm(-2) and a flat band voltage shift of 2.0 V. A unique feature of the double loop in the C-V curves suggests double barriers during electron tunneling. The I-V hysteresis is also characterized, and a switching mechanism of resistive change is discussed.

Characterization of the interface between the Hf-based high-k thin film and the Si using spatially resolved electron energy-loss spectroscopy.

The interfacial structures of HfO(2) and HfAlO thin films on Si have been investigated using spatially resolved electron energy-loss spectroscopy. We have found that interfaces are not atomically sharp, and variation in the symmetry of the local atomic coordination lasts for a couple of monolayers for both the as-deposited HfO(2) and the HfAlO samples. Annealing of the HfO(2) film in the oxygen environment leads to the formation of a thick SiO(2)/SiO(x) stack layer in-between the original HfO(2) and the Si substrate. As a comparison, the interfacial stability is significantly improved by Al incorporation into the HfO(2) film (forming HfAlO), which effectively reduced/eliminated the interfacial silicon oxide formation during the oxygen annealing process. The mechanism of the high-k film/substrate stabilization by Al incorporation is discussed based on the experimental results.

Multiple matching scheme for broadband 0.72Pb(Mg(13)Nb(23))O(3)-0.28PbTiO(3) single crystal phased-array transducer.

Lead magnesium niobate-lead titanate single crystal 0.72Pb(Mg(13)Nb(23))O(3)-0.28PbTiO(3) (abbreviated as PMN-PT) was used to fabricate high performance ultrasonic phased-array transducer as it exhibited excellent piezoelectric properties. In this paper, we focus on the design and fabrication of a low-loss and wide-band transducer for medical imaging applications. A KLM model based simulation software PiezoCAD was used for acoustic design of the transducer including the front-face matching and backing. The calculated results show that the -6 dB transducer bandwidth can be improved significantly by using double lambda8 matching layers and hard backing. A 4.0 MHz PMN-PT transducer array (with 16 elements) was fabricated and tested in a pulse-echo arrangement. A -6 dB bandwidth of 110% and two-way insertion loss of -46.5 dB were achieved.

Survey of excited state neutron spectroscopic factors for Z=8-28 nuclei.

We have extracted 565 neutron spectroscopic factors of sd and fp shell nuclei by systematically analyzing more than 2000 measured (d, p) angular distributions. We are able to compare 125 of the extracted spectroscopic factors to values predicted by large-basis shell-model calculations and evaluate the accuracies of spectroscopic factors predicted by different shell-model interactions in these regions. We find that the spectroscopic factors predicted for most excited states of sd-shell nuclei using the latest USDA or USDB interactions agree with the experimental values. For fp shell nuclei, the inability of the current models to account for the core excitation and fragmentation of the states leads to considerable discrepancies. In particular, the agreement between data and shell-model predictions for Ni isotopes is not better than a factor of 2 using either the GXPF1A or the XT interaction.