A Nano- to Macroscale Tribological Study of PFTS and TCP Lubricants for Si MEMS Applications

The reliability and lifetime of cyclic contacting Si MEMS is limited by adhesion and their tribological performance. In this study, the tribological effects of adding a lubricant (tricresyl phosphate, TCP) to a bound self-assembled monolayer (perfluorodecyltrichlorosilane, PFTS) at different length scales were examined using a quartz crystal microbalance (QCM), an atomic force microscope (AFM), a reciprocating microtribometer, and a macroscopic reciprocating tribometer. The results showed that the addition of TCP to a PFTS layer increased the number of cycles possessing low friction and wear by at least a factor of four in the macroscopoic tribometer. Differences in friction response over the range of experimental scales were correlated to contact size and pressure. QCM measurements of TCP on PFTS showed a non-zero slip time, which suggests favorable tribological performance in larger length-scale regimes. This non-zero slip time also may indicate TCP mobility.     

Heat transfer and exergy analysis of cascaded latent heat storage with gravity-assisted heat pipes for concentrating solar power applications

A thermal network model is developed to predict the performance of latent heat thermal energy storage (LHTES) systems including cascaded phase change materials (PCMs) and embedded heat pipes/thermosyphons. Because the design of LHTES systems involves a compromise between the amount of energy stored, the heat transfer rate, and the quality of the released thermal energy, an exergy analysis is also carried out to identify the preferred LHTES design. It is found that the LHTES with the lowest melting temperature PCM yields the highest exergy efficiency. However, a cascaded LHTES recovers the largest amount of exergy during a 24 h charging–discharging cycle. Quantitatively, the cascaded LHTES recovers about 10% more exergy during a 24 h charging–discharging cycle compared to the best non-cascaded LHTES considered in this work.     

Exploring three-dimensional matrix-assisted laser desorption/ionization imaging mass spectrometry data: three-dimensional spatial segmentation of mouse kidney

Three-dimensional (3D) imaging has a significant impact on many challenges of life sciences. Three-dimensional matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) is an emerging label-free bioanalytical technique capturing the spatial distribution of hundreds of molecular compounds in 3D by providing a MALDI mass spectrum for each spatial point of a 3D sample. Currently, 3D MALDI-IMS cannot tap its full potential due to the lack efficient computational methods for constructing, processing, and visualizing large and complex 3D MALDI-IMS data. We present a new pipeline of efficient computational methods, which enables analysis and interpretation of a 3D MALDI-IMS data set. Construction of a MALDI-IMS data set was done according to the state-of-the-art protocols and involved sample preparation, spectra acquisition, spectra preprocessing, and registration of serial sections. For analysis and interpretation of 3D MALDI-IMS data, we applied the spatial segmentation approach which is well-accepted in analysis of two-dimensional (2D) MALDI-IMS data. In line with 2D data analysis, we used edge-preserving 3D image denoising prior to segmentation to reduce strong and chaotic spectrum-to-spectrum variation. For segmentation, we used an efficient clustering method, called bisecting k-means, which is optimized for hierarchical clustering of a large 3D MALDI-IMS data set. Using the proposed pipeline, we analyzed a central part of a mouse kidney using 33 serial sections of 3.5 μm thickness after the PAXgene tissue fixation and paraffin embedding. For each serial section, a 2D MALDI-IMS data set was acquired following the standard protocols with the high spatial resolution of 50 μm. Altogether, 512?495 mass spectra were acquired that corresponds to approximately 50 gigabytes of data. After registration of serial sections into a 3D data set, our computational pipeline allowed us to reveal the 3D kidney anatomical structure based on mass spectrometry data only. Finally, automated analysis discovered molecular masses colocalized with major anatomical regions. In the same way, the proposed pipeline can be used for analysis and interpretation of any 3D MALDI-IMS data set in particular of pathological cases.     

Asynchronous magnetic bead rotation microviscometer for rapid, sensitive, and label-free studies of bacterial growth and drug sensitivity

The long turnaround time in antimicrobial susceptibility testing (AST) endangers patients and encourages the administration of wide spectrum antibiotics, thus resulting in alarming increases of multidrug resistant pathogens. A method for faster detection of bacterial proliferation presents one avenue toward addressing this global concern. We report on a label-free asynchronous magnetic bead rotation (AMBR) based viscometry method that rapidly detects bacterial growth and determines drug sensitivity by measuring changes in the suspension's viscosity. With this platform, we observed the growth of a uropathogenic Escherichia coli isolate, with an initial concentration of 50 cells per drop, within 20 min; in addition, we determined the gentamicin minimum inhibitory concentration (MIC) of the E. coli isolate within 100 min. We thus demonstrated a label-free, microviscometer platform that can measure bacterial growth and drug susceptibility more rapidly, with lower initial bacterial counts than existing commercial systems, and potentially with any microbial strains.     

Green Tea Ingestion by Rats Does Not Affect Iron Absorption but Does Alter the Composition of the Saliva Proteome

Abstract: We tested the hypothesis that rats adapt to the iron absorption inhibitory effects of tea by modifying the expression of salivary proteins. Thirty‐six weanling rats were allocated into 6 groups. Two control groups were fed a semipurified diet containing 20 mg Fe²⁺/kg diet. Two groups were fed spray dried green tea infusion mixed into the diet (28.6 g tea/kg diet) and 2 groups were fed the control diet with a twice daily gavage of a tea solution (0.25 g tea/mL). Saliva samples were collected in 3 groups (control, gavage, and oral) on day 8 (acute) and in the remaining groups on day 31 (chronic). Iron absorption was assessed using a ⁵⁸Fe³⁺ tracer administered on day 1 (acute) and day 24 (chronic). 2D gel electrophoresis and mass spectrometry were used to assess the composition of the saliva proteome. There was no significant difference in iron absorption between the 3 groups on either day 1 or day 24. Salivary proline‐rich proteins and submandibular gland secretory protein increased to a greater extent in the oral group than in the gavage group, when compared to control, within the same exposure time period. Amylase, chitinase, deoxyribonuclease, cysteine‐rich secretory protein 1, and parotid secretory protein all decreased to a greater extent in the oral tea group, compared to the control, within the same exposure time period. Our results show that green tea did not decrease iron absorption in rats but it did have a marked effect on the saliva proteome when given orally.     

Muscular and Molecular Pathology Associated with SPATA5 Deficiency in a Child with EHLMRS

Mutations in the SPATA5 gene are associated with epilepsy, hearing loss and mental retardation syndrome (EHLMRS). While SPATA5 is ubiquitously expressed and is attributed a role within mitochondrial morphogenesis during spermatogenesis, there is only limited knowledge about the associated muscular and molecular pathology. This study reports on a comprehensive workup of muscular pathology, including proteomic profiling and microscopic studies, performed on an 8-year-old girl with typical clinical presentation of EHLMRS, where exome analysis revealed two clinically relevant, compound-heterozygous variants in SPATA5. Proteomic profiling of a quadriceps biopsy showed the dysregulation of 82 proteins, out of which 15 were localized in the mitochondrion, while 19 were associated with diseases presenting with phenotypical overlap to EHLMRS. Histological staining of our patient’s muscle biopsy hints towards mitochondrial pathology, while the identification of dysregulated proteins attested to the vulnerability of the cell beyond the mitochondria. Through our study we provide insights into the molecular etiology of EHLMRS and provide further evidence for a muscle pathology associated with SPATA5 deficiency, including a pathological histochemical pattern accompanied by dysregulated protein expression.     

Validation of a Real-Time PCR On-Site Quantification Method for MON810 Maize

A rapid on-, or near-site, quantitative method for use as a pre-harvest predictive decision, or co-existence monitoring, tool for adventitious genetically modified (GM) presence has been developed. Based on a laboratory-based protocol for real-time (RT) quantification of the MON810 GM event in maize kernels, the duplex RT polymerase chain reaction method was constructed around the portable Cepheid SmartCyclerII platform, requiring only modest support infrastructure for field application. Validation through an international ring trial showed good compliance with minimum assay performance requirements as defined by the European Network of GMO Laboratories (RSD_r = 18.5%; RSD_R = 32.8; Bias = 26.7%).     

Performance Evaluation of the Enhanced MI-MAC Protocol for Multimedia Integration over Wireless Cellular Networks

In recent work (Koutsakis et al., IEEE Trans Veh Technol 54(5):1863–1874, 2005), we have introduced multimedia integration multiple access control protocol (MI-MAC). The protocol was shown to achieve superior performance in comparison to other protocols of the literature when integrating various types of multimedia traffic over wireless cellular networks. In this work we enhance the scheduling scheme of MI-MAC by adding three important parameters into its study. These are: (a) the handling of handoff traffic, (b) per user varying channel conditions in the uplink and downlink channels and (c) video sources’ contention for channel resources. These parameters are added in order to evaluate the protocol under a significantly more realistic wireless cellular network scenario. New scheduling ideas are proposed in order to efficiently incorporate the new parameters into the scheme. The evaluation, conducted by comparing the enhanced MI-MAC with another efficient protocol of the literature and with an “ideal” MAC protocol, focuses on the efficient transmission of MPEG-4 video traffic and shows that our scheme achieves excellent performance results.

Preferential Nucleation of Metallic Clusters on a Nanotemplate: Co on Oxygen-Faceted Re(12 \overline{3} 1)

Preferential nucleation of cobalt nanoclusters at specific sites on oxidized faceted Re(12 $ \overline{3} $ 1) is investigated by means of Auger electron spectroscopy (AES), low energy electron diffraction (LEED), and scanning tunneling microscopy (STM). An oxygen terminated nanofaceted Re surface containing ridges and valleys is used as the nanotemplate in this study. Deposition of cobalt onto this surface, followed by annealing to ~800 K, results in preferential cobalt nanocluster nucleation and growth within the valleys of the nanofaceted surface. Decreasing the nanofacet width, cobalt coverage, and annealing temperature lead to the same preferential cobalt nanocluster self assembly, an increase in nanocluster density, and a decrease in nanocluster volume. The preferential nucleation and growth observed for Co nanoclusters on faceted Re makes this a model system for future studies of different substrates and metallic overlayers more relevant to catalytic reactions.