Outwitting the series resistance in scanning spreading resistance microscopy

The performance of nanoelectronics devices critically depends on the distribution of active dopants inside these structures. For this reason, dopant profiling has been defined as one of the major metrology challenges by the international technology roadmap of semiconductors. Scanning spreading resistance microscopy (SSRM) has evolved as one of the most viable approaches over the last decade due to its excellent spatial resolution, sensitivity and quantification accuracy. However, in case of advanced device architectures like fins and nanowires a proper measurement of the spreading resistance is often hampered by the increasing impact of parasitic series resistances (e.g. bulk series resistance) arising from the confined nature of the aforementioned structures. In order to overcome this limitation we report in this paper the development and implementation of a novel SSRM mode (fast Fourier transform-SSRM: FFT-SSRM) which essentially decouples the spreading resistance from parasitic series resistance components. We show that this can be achieved by a force modulation (leading to a modulated spreading resistance signal) in combination with a lock-in deconvolution concept. In this paper we first introduce the principle of operation of the technique. We discuss in detail the underlying physical mechanisms as well as the technical implementation on a state-of-the-art atomic force microscope (AFM). We demonstrate the performance of FFT-SSRM and its ability to remove substantial series resistance components in practice. Eventually, the possibility of decoupling the spreading resistance from the intrinsic probe resistance will be demonstrated and discussed.

Effects of down-regulated steroidogenic factor-1 on ACTH and potassium chloride-induced steroid synthesis in H295R cells

The prevalence of adrenal diseases in the cortex is more common than that in the medulla in the form of hormone disorder or neoplasm. Steroidogenic factor—1 (SF—1) is important in regulating aldosterone synthase (CYP11B2) and cortisol synthase (CYP11B1). SF—1 is increased in aldosterone—producing adenoma (APA) and cortisol—producing adenoma (CPA). Overexpression of SF—1 has been extensively studied, but the available in—depth information regarding the effects of downregulated SF—1 on CYP11B2/CYP11B1 and their regulators is limited. In this paper, we attempted to investigate the effects of downregulated SF—1 on aldosterone to adrenocorticotropic hormone (ACTH) and potassium chloride (KCl) stimulation and those on cortisol to ACTH stimulation through RNA interference in acute and chronic phases. Downregulated SF—1 decreased the sensitivity of aldosterone to ACTH/KCl and that of cortisol to ACTH stimulation. This study provides new insights into the influence of SF—1 on adrenocortical diseases by considering the effects of SF—1 on regulation.

Instantaneous quantification of skeletal muscle activation, power production, and fatigue during cycle ergometry

A rapid switch from hyperbolic to isokinetic cycling allows the velocity-specific decline in maximal power to be measured, i.e., fatigue. We reasoned that, should the baseline relationship between isokinetic power (Piso) and electromyography (EMG) be reproducible, then contributions to fatigue may be isolated from 1) the decline in muscle activation (muscle activation fatigue); and 2) the decline in Piso at a given activation (muscle fatigue). We hypothesized that the EMG-Piso relationship is linear, velocity dependent, and reliable for instantaneous fatigue assessment at intolerance during and following whole body exercise. Healthy participants (n = 13) completed short (5 s) variable-effort isokinetic bouts at 50, 70, and 100 rpm to characterize baseline EMG-Piso. Repeated ramp incremental exercise tests were terminated with maximal isokinetic cycling (5 s) at 70 rpm. Individual baseline EMG-Piso relationships were linear (r(2) = 0.95 ± 0.04) and velocity dependent (analysis of covariance). Piso at intolerance (two legs, 335 ± 88 W) was ∼45% less than baseline [630 ± 156 W, confidence interval of the difference (CIDifference) 211, 380 W, P < 0.05]. Following intolerance, Piso recovered rapidly (F = 44.1; P < 0.05; η(2) = 0.79): power was reduced (P < 0.05) vs. baseline only at 0-min (CIDifference 80, 201 W) and 1-min recovery (CIDifference 13, 80 W). Activation fatigue and muscle fatigue (one leg) were 97 ± 55 and 60 ± 50 W, respectively. Mean bias ± limits of agreement for reproducibility were as follows: baseline Piso 1 ± 30 W; Piso at 0-min recovery 3 ± 35 W; and EMG at Piso 3 ± 14%. EMG power is linear, velocity dependent, and reproducible. Deviation from this relationship at the limit of tolerance can quantify the "activation" and "muscle" related components of fatigue during cycling.

Scaling perceived saturation

Two psychophysical experiments were conducted at North Carolina State University (NCSU) and Rochester Institute of Technology (RIT) to obtain replicated perceived saturation data from color normal observers on the order of one unit of saturation. The same 37 Munsell sample sheets, including up to four references that had similar perceived saturation but different hue, were used in both experiments. Different assessment methods included presenting either four references simultaneously or only one reference at a time to observers and obtaining judged saturation magnitudes for the given Munsell samples. Four saturation models comprising Sab*, Suv*, CIECAM02, as well as Richter/Lübbe, were tested. CIECAM02 gave the best prediction of saturation for data obtained at NCSU while Sab* outperformed other models for the RIT data. For the combined dataset, Sab*, the Richter/Lübbe, and CIECAM02-based saturation models exhibited comparable performances. The Standardized Residual Sum of Squares index was used to measure the inter- and intra-observer variability and goodness of fit. Inter- and intra-observer variability of assessments was smaller than or comparable to those reported for the typical color difference evaluation experiments.

Performance of select color-difference formulas in the blue region

The main objective of this work was to test the performance of major formulas for assessment of small suprathreshold color differences in the blue region. The models examined include CIELAB color space based equations, including CIELAB, CIE94, CIEDE2000, CMC (l:c), BFD (l:c), and formulas based on more uniform color spaces, such as DIN99d, CAM02-SCD, CAM02-UCS, OSA-GP, and OSA-Eu in comparison against data obtained via visual assessments. For this purpose, a dataset around the CIE high-chroma blue color center, hereafter called NCSU-B2, was developed. The NCSU-B2 dataset comprised 65 textile substrates and a standard, with a mean ΔE(ab)* color difference of 2.72, ranging from 0.54-5.72. Samples were visually assessed by 26 subjects against the reference gray scale in three separate trials with at least 24 h between assessments. A total of 5070 assessments were obtained. The standardized residual sum of squares (STRESS) index was used to examine the performance of various formulas for this dataset, as well as a previously developed NCSU-B1 low-chroma blue dataset [Color Res. Appl. 36, 27, 2011], and blue centers from other established visual datasets. Results show that formulas based on more recent uniform color spaces provide better agreement with perceptual data compared with models based on CIELAB space.

Effect of docosahexaenoic acid on hippocampal neurons in high-glucose condition: involvement of PI3K/AKT/nuclear factor-κB-mediated inflammatory pathways

Accumulating evidence suggested that hyperglycemia played a critical role in hippocampus dysfunction in patients with diabetes mellitus. However, the multifactorial pathogenesis of hyperglycemia-induced impairments of hippocampal neurons has not been fully elucidated. Docosahexaenoic acid (DHA) has been shown to enhance learning and memory and affect neural function in various experimental conditions. The present study investigated the effects of DHA on the lipid peroxidation, the level of inflammatory cytokines and neuron apoptosis in the hippocampal neurons in high-glucose condition. High-glucose administration increased the level of tumor necrosis factor α (TNF-α) and IL-6, induced oxidative stress and apoptosis of hippocampal neurons in vitro. DHA treatment reduced oxidative stress and TNF-α expression, protected the hippocampal neurons by increasing AKT phosphorylation and decreasing caspase-3 and caspase-9 expression. These results suggested that high-glucose exposure induced injury of hippocampal neurons in vitro, and the principle mechanisms involved in the neuroprotective effect of DHA were its antioxidant and anti-apoptotic potential. DHA may thus be of use in preventing or treating neuron-degeneration resulting from hyperglycemia.

CGG allele size somatic mosaicism and methylation in FMR1 premutation alleles

BACKGROUND

Greater than 200 CGG repeats in the 5'UTR of the FMR1 gene lead to epigenetic silencing and lack of the FMR1 protein, causing fragile X Syndrome. Individual carriers of a premutation (PM) allele with 55-200 CGG repeats are typically unmethylated and can present with clinical features defined as FMR1-associated conditions.

METHODS

Blood samples from 17 male PM carriers were assessed clinically and molecularly by Southern blot, western blot, PCR and QRT-PCR. Blood and brain tissue from an additional 18 PM males were also similarly examined. Continuous outcomes were modelled using linear regression and binary outcomes were modelled using logistic regression.

RESULTS

Methylated alleles were detected in different fractions of blood cells in all PM cases (n=17). CGG repeat numbers correlated with percent of methylation and mRNA levels and, especially in the upper PM range, with greater number of clinical involvements. Inter-tissue/intra-tissue somatic instability and differences in percent methylation were observed between blood and fibroblasts (n=4) and also observed between blood and different brain regions in three of the 18 PM cases examined. CGG repeat lengths in lymphocytes remained unchanged over a period of time ranging from 2 to 6 years, three cases for whom multiple samples were available.

CONCLUSIONS

In addition to CGG size instability, individuals with a PM expanded allele can exhibit methylation and display more clinical features likely due to RNA toxicity and/or FMR1 silencing. The observed association between CGG repeat length and percent of methylation with the severity of the clinical phenotypes underscores the potential value of methylation in affected PM to further understand penetrance, inform diagnosis and expand treatment options.

Application of evaporative cooling technology in super-high power density magnet

Evaporative cooling technology utilizes phase-change heat transfer mode to achieve the cooling for heating equipment. The heat transfer capacity of evaporative cooling technology is far more than air or water cooling technology. The Electron Cyclotron Resonance ion source magnet is a typical super-high power density magnet, and the evaporative cooling technology is an ideal cooling method for the coils of magnet. In this paper we show the structure and process of coils and the special design of flow channels of coolant for an experiment magnet model. Additionally, the heat transfer circulation is presented and analyzed. By the finite element method, the flow channels are optimized to rationally allocate coolant and to reduce the temperature of coils. For the experiment model, the current density of copper wire of coils is 19 A/mm(2), and the coil-windows current density is larger than 12 A/mm(2). The max temperature of coils is below 80 °C, and the total heat is about 200 kW.

Progress of a room temperature electron cyclotron resonance ion source using evaporative cooling technology at Institute of Modern Physics

A new room temperature ECR ion source, Lanzhou Electron Cyclotron Resonance ion source No. 4 (LECR4, previously named DRAGON), is under intense construction at Institute of Modern Physics. LECR4 is designed to operate with 18 GHz microwave frequency. The maximum axial magnetic fields are 2.3 T at injection and 1.3 T at extraction, and the radial field at the plasma chamber wall of 76 mm inner diameter is 1.0-1.2 T. One of the unique features for LECR4 is that its axial solenoids are winded with solid square copper wires which are immersed in a kind of special evaporative cooling medium for cooling purpose. Till now, a prototype of the cooling system has been successfully constructed and tested, which has demonstrated that the cooling efficiency of the designed system could meet the requirements of LECR4 under the routine operation conditions. All the main components of the ion source have been completed. Assembly and commissioning is ongoing. The latest developments and test results will be presented in this paper.

A novel methylation PCR that offers standardized determination of FMR1 methylation and CGG repeat length without southern blot analysis

Fragile X syndrome and associated disorders are characterized by the number of CGG repeats and methylation status of the FMR1 gene for which Southern blot (SB) historically has been required for analysis. This study describes a simple PCR-only workflow (mPCR) to replace SB analysis, that incorporates novel procedural controls, treatment of the DNA in separate control and methylation-sensitive restriction endonuclease reactions, amplification with labeled primers, and two-color amplicon sizing by capillary electrophoresis. mPCR was evaluated in two independent laboratories with 76 residual clinical samples that represented typical and challenging fragile X alleles in both males and females. mPCR enabled superior size resolution and analytical sensitivity for size and methylation mosaicism compared to SB. Full mutation mosaicism was detected down to 1% in a background of 99% normal allele with 50- to 100-fold less DNA than required for SB. A low level of full mutation mosaicism in one sample was detected using mPCR but not observed using SB. Overall, the sensitivity for detection of full mutation alleles was 100% (95% CI: 89%-100%) with an accuracy of 99% (95% CI: 93%-100%). mPCR analysis of DNA from individuals with Klinefelter and Turner syndromes, and DNA from sperm and blood, were consistent with SB. As such, mPCR enables accurate, sensitive, and standardized methods of FMR1 analysis that can harmonize results across different laboratories.

Rescue from dominant follicle atresia by follicle-stimulating hormone in mice

We investigated the effects of follicle-stimulating hormone (FSH) on atresia of the dominant follicle and changes in relevant apoptosis genes in granulosa cells of dominant follicles regulated by FSH in vivo. Four-week-old mice were administered FSH by intraperitoneal injection to induce follicular maturation. Granulosa cells of dominant follicles were collected at 48, 72, and 96 h after the first FSH injection. Phosphate-buffered saline was injected as a control. The mRNA levels of relevant granulosa cell apoptosis genes were examined by real-time quantitative polymerase chain reaction, and apoptosis of granulosa cells in dominant ovarian follicles was determined by the terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay. Apoptosis in granulosa cells of dominant follicles was almost TUNEL-negative at 48, 72-66, 72, and 96-90 h after the first FSH injection, but granulosa cell apoptosis in dominant follicles was clearly detected at 96, 102, and 102-96 h by TUNEL. The BIM, caspase-3, and caspase-9 mRNA expression levels were significantly lower after FSH treatment at 72-66 and 96-90 h, compared with that at 72 and 96 h (P < 0.05). Caspase-8 and FasL mRNA expressions did not respond to FSH. FSH rescued granulosa cells from apoptosis when the relevant apoptosis genes were upregulated in early atretic follicles. FSH did not rescue granulosa cells from apoptosis if the DNA was cut into fragments by endonucleases. Thus, the rescue by FSH of granulosa cells from apoptosis and dominant follicle atresia may be accomplished by inhibition of apoptosis in mitochondria.

Physiology and morphology of inverted pyramidal neurons in the rodent neocortex

An increasing number of studies indicate that there exists greater diversity of cortical neurons than previously appreciated. In the present report, we use a combination of physiological and morphological methods to characterize cortical neurons in infragranular layers with apical dendrites pointing toward the white-matter compared to those neurons with apical dendrites pointing toward the pia in both mouse and rat neocortex. Several features of the dendritic morphology and intrinsic and synaptic physiology of these "inverted" neurons revealed numerous differences among this cell type between species. We also found differences between the different cell types within the same species. These data reveal that similar cell types in the rat and mouse may not always share similar physiological and morphological properties. These data are relevant to models of information processing through micro- and larger neocortical circuits and indicate that different cell types found within similar lamina can have different functional properties.