A high-frequency annular-array transducer using an interdigital bonded 1-3 composite

This paper reports the design, fabrication, and characterization of a 1-3 composite annular-array transducer. An interdigital bonded (IB) 1-3 composite was prepared using two IB operations on a fine-grain piezoelectric ceramic. The final composite had 19-μm-wide posts separated by 6-μm-wide polymer kerfs. A novel method to remove metal electrodes from polymer portions of the 1-3 composite was established to eliminate the need for patterning and aligning the electrode on the composite to the electrodes on a flexible circuit. Unloaded epoxy was used for both the matching and backing layers and a flexible circuit was used for interconnect. A prototype array was successfully fabricated and tested. The results were in reasonable agreement with those predicted by a circuit-analogous model. The average center frequency estimated from the measured pulse-echo responses of array elements was 33.5 MHz and the -6-dB fractional bandwidth was 57%. The average insertion loss recorded was 14.3 dB, and the maximum crosstalk between the nearest-neighbor elements was less than -37 dB. Images of a wire phantom and excised porcine eye were obtained to show the capabilities of the array for high-frequency ultrasound imaging.     

Interfacing cell-based assays in environmental scanning electron microscopy using dielectrophoresis

Development of the dielectrophoretic (DEP) live cell trapping technology and its interfacing with the environmental scanning electron microscopy (ESEM) is described. DEP microelectrode arrays were fabricated on glass substrate using photolithography and lift-off. Chip-based arrays were applied for ESEM analysis of DEP-trapped human leukemic cells. This work provides proof-of-concept interfacing of the DEP cell retention and trapping technology with ESEM to provide a high-resolution analysis of individual nonadherent cells.     

Synergistic effect of thermophilic temperature and biosurfactant produced by Acinetobacter calcoaceticus BU03 on the biodegradation of phenanthrene in bioslurry system

This study aimed at investigating the synergistic effect of temperature and biosurfactant on the biodegradation of phenanthrene in bioslurry. Bench-scale bioslurry experiments were conducted at 25 and 55°C. The desorption rate coefficients of phenanthrene (K(des)) obtained using the pseudo-first order model were 0.0026 and 0.0035 kg mg(-1)h(-1) at 25 and 55°C, respectively. Addition of 1500 mg L(-1) biosurfactant, produced by Acinetobacter calcoaceticus BU03, marginally increased the K(des) at 25°C since most of biosurfactant was sorbed onto soil; however, significantly increased the K(des) to 0.0087 kg mg(-1)h(-1) at 55°C as the thermophilic temperature reduced the adsorption of the biosurfactant onto soil and subsequently enhanced the desorption of phenanthrene. The biodegradation of phenanthrene well fitted pseudo-first order kinetics based on the assumption that biodegradation was limited by the desorption. About 78.7% of phenanthrene was degraded in 30 days at 25°C; and addition of biosurfactant did not affect the biodegradation. However, addition of the biosurfactant or inoculation of A. calcoaceticus BU03 at 55°C significantly enhanced the biodegradation by increasing the K(des). Results indicate that synergistic application of thermophilic temperature and biosurfactant or inoculation of biosurfactant producing microorganisms is an effective and innovative method to enhance the efficiency of PAH degradation in bioslurry system.     

Transforming the fabrication and biofunctionalization of gold nanoelectrode arrays into versatile electrochemical glucose biosensors

High-density arrays of conducting nanoelectrodes (i.e., nanoelectrode arrays [NEAs]) have been developed on the surface of a single electrode for numerous electrochemical sensing paradigms. However, a scalable fabrication technique and robust biofunctionalization protocol are oftentimes lacking and thus many NEA designs have limited efficacy and overall commercial viability in biosensing applications. In this report, we develop a lithography-free nanofabrication protocol to create large arrays of Au nanoelectrodes on a silicon wafer via a porous anodic alumina template. To demonstrate their effectiveness as electrochemical glucose biosensors, alkanethiol self-assembled monolayers (SAMs) are used to covalently attach the enzyme glucose oxidase to the Au NEA surface for subsequent glucose sensing. The sensitivity and linear sensing range of the biosensor is controlled by introducing higher concentrations of long-chain SAMs (11-mercaptoundecanoic acid: MUA) with short-chain SAMs (3-mercaptopropionic acid: MPA) into the enzyme immobilization scheme. This facile NEA fabrication protocol (that is well-suited for integration into electronic devices) and biosensor performance controllability (via the mixed-length enzyme-conjugated SAMs) transforms the Au NEAs into versatile glucose biosensors. Thus these Au NEAs could potentially be used in important real-word applications such as in health-care and bioenergy where biosensors with very distinct sensing capabilities are needed.     

A Versatile Nonviral Delivery System for Multiplex Gene-Editing in the Liver

Recent advances in CRISPR present attractive genome-editing toolsets for therapeutic strategies at the genetic level. Here, a liposome-coated mesoporous silica nanoparticle (lipoMSN) is reported as an effective CRISPR delivery system for multiplex gene-editing in the liver. The MSN provides efficient loading of Cas9 plasmid as well as Cas9 protein/guide RNA ribonucleoprotein complex (RNP), while liposome-coating offers improved serum stability and enhanced cell uptake. Hypothesizing that loss-of-function mutation in the lipid-metabolism-related genes pcsk9, apoc3, and angptl3 would improve cardiovascular health by lowering blood cholesterol and triglycerides, the lipoMSN is used to deliver a combination of RNPs targeting these genes. When targeting a single gene, the lipoMSN achieved a 54% gene-editing efficiency, besting the state-of-art Lipofectamine CRISPRMax. For multiplexing, lipoMSN maintained significant gene-editing at each gene target despite reduced dosage of target-specific RNP. By delivering combinations of targeting RNPs in the same nanoparticle, synergistic effects on lipid metabolism are observed in vitro and vivo. These effects, such as a 50% decrease in serum cholesterol after 4 weeks of post-treatment with lipoMSN carrying both pcsk9 and angptl3-targeted RNPs, could not be reached with a single gene-editing approach. Taken together, this lipoMSN represents a versatile platform for the development of efficient, combinatorial gene-editing therapeutics.     

Adaptive Liquid Interfacially Assembled Protein Nanosheets for Guiding Mesenchymal Stem Cell Fate

There is a growing interest in the development of dynamic adaptive biomaterials for regulation of cellular functions. However, existing materials are limited to two-state switching of the presentation and removal of cell-adhesive bioactive motifs that cannot emulate the native extracellular matrix (ECM) in vivo with continuously adjustable characteristics. Here, tunable adaptive materials composed of a protein monolayer assembled at a liquid–liquid interface are demonstrated, which adapt dynamically to cell traction forces. An ultrastructure transition from protein monolayer to hierarchical fiber occurs through interfacial jamming. Elongated fibronectin fibers promote formation of elongated focal adhesion structures, increase focal adhesion kinase activation, and enhance neuronal differentiation of stem cells. Cell traction force results in spatial rearrangement of ECM proteins, which feeds back to alter stem cell fate. The reported biomimetic adaptive liquid interface enables dynamic control of stem cell behavior and has potential translational applications.     

Memory and Emotions for the September 11, 2001, Terrorist Attacks in Patients With Alzheimer's Disease, Patients With Mild Cognitive Impairment, and Healthy Older Adults.

National traumatic events can produce extremely vivid memories. Using a questionnaire administered during telephone interviews, the authors investigated emotional responses to, and memory for. the September 11, 2001, terrorist attacks in patients with Alzheimer's disease (AD), patients with mild cognitive impairment (MCI), and healthy older adults in the initial weeks following the event and again 3-4 months later. There were several notable findings. First, patients with AD showed less memory than patients with MCI and older adults. Second, patients with AD, but not patients with MCI or older adults, appeared to retain more memory for personal versus factual information. Third, patients with AD and older adults did not differ in the intensity of their reported emotional responses to the attacks, whereas patients with MCI reported relatively less intense emotional responses. Last, distortions of memory for personal information were frequent for all participants but were more common in patients with AD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Associative Memory Deficit of Older Adults: Further Support Using Face-Name Associations.

Previous studies have established an associative deficit hypothesis (Naveh-Benjamin, 2000), which attributes part of older adults' deficient episodic memory performance to their difficulty in creating cohesive episodes. In this article, the authors further evaluate this hypothesis, using ecologically relevant materials. Young and old participants studied name-face pairs and were then tested on their recognition memory for the names, faces, and the name-face pairs. The results extend the conditions under which older adults exhibit an associative deficit. They also show that reduced attentional resources are not the sole mediator of this deficit. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Tale of Two Cities: Financing Two Voucher Programs for Substance Abusers Through Community Donations.

Voucher-based reinforcement therapy (VBRT) is an effective drug abuse treatment, but the cost of VBRT rewards has limited its dissemination. Obtaining VBRT incentives through donations may be one way to overcome this barrier. Two direct mail campaigns solicited donations for use in VBRT for pregnant, postpartum, and parenting drug users in Toronto, Ontario, Canada, and in Los Angeles, California. In Toronto, 19% of those contacted over 2 months donated $8,000 ($4,000/month) of goods and services. In Los Angeles, nearly 26% of those contacted over 34 months donated $161,000 ($4,472/month) of goods and services. Maintaining voucher programs by soliciting donations is feasible and sustainable. The methods in this article can serve as a guide for successful donation solicitation campaigns. Donations offer an alternative for obtaining VBRT rewards for substance abuse treatment and may increase its dissemination. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Using technology to explore social networks and mechanisms underlying peer effects in classrooms.

Peer interactions among children have long interested social scientists. Identifying causal peer effects is difficult, and a number of studies have used random assignment to produce evidence that peers affect each other's outcomes. This focus by sociologists and economists on whether peers affect each other has not been matched by direct evidence on how these effects operate. The authors argue that one reason for the small number of studies in sociology and economics on the mechanisms underlying peer effects is the difficulty of collecting data on microinteractions. They argue technology reduces data collection costs relative to direct observation and allows for realistic school activities with randomly assigned peers. The authors describe a novel strategy for collecting data on peer interactions and discuss how this approach might shed light on mechanisms underlying peer influence. The centerpiece of this strategy is the use of handheld computers by middle and high school students as part of interactive math and science lessons called the Discussion Game. The handhelds collect data on interactions between students and track how students' answers evolve as they interact with different peers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)