Arbitrary cross-section SEM-cathodoluminescence imaging of growth sectors and local carrier concentrations within micro-sampled semiconductor nanorods

Future one-dimensional electronics require single-crystalline semiconductor free-standing nanorods grown with uniform electrical properties. However, this is currently unrealistic as each crystallographic plane of a nanorod grows at unique incorporation rates of environmental dopants, which forms axial and lateral growth sectors with different carrier concentrations. Here we propose a series of techniques that micro-sample a free-standing nanorod of interest, fabricate its arbitrary cross-sections by controlling focused ion beam incidence orientation, and visualize its internal carrier concentration map. ZnO nanorods are grown by selective area homoepitaxy in precursor aqueous solution, each of which has a (0001):+c top-plane and six {1–100}:m side-planes. Near-band-edge cathodoluminescence nanospectroscopy evaluates carrier concentration map within a nanorod at high spatial resolution (60 nm) and high sensitivity. It also visualizes +c and m growth sectors at arbitrary nanorod cross-section and history of local transient growth events within each growth sector. Our technique paves the way for well-defined bottom-up nanoelectronics

Analysis of the Characteristics of Patients Presenting with Exacerbation of Asthma to Emergency Care Units

Background:Fatal asthma remains a serious problem, and patient self-management of asthma is important to prevent exacerbation. To reduce the asthma mortality rate, we analyzed the characteristics of patients who visited an emergency care unit with exacerbation of asthma.Methods:Subjects were 317 patients(135 men, 182 women;mean age, 47.0 years)who visited the emergency room at Dokkyo Medical University Hospital or Dokkyo Medical University Koshigaya Hospital for exacerbation of asthma between April 2010 and March 2011. When categorized by severity, 41.3% ofpatients were step 1, 8.2% were step 2, 18.9% were step 3, 30.9% were step 4, and 0.6% were unknown. When categorized by primary care physician, 60.3% of patients had a primary care physician at Dokkyo Medical University, 13.6% had one at another hospital, and 26.2% had no primary care physician. When categorized by recovery from exacerbation, control was achieved within 1 day in 63.1% of cases, after more than 1 day in 30.6% of cases, and required admission in 6.3% of cases.Results:The rate of admissions was highest for cases with step 1 severity(step 1, 55.0%;step 2, 20.0%;step 3, 0.0%;and step 4, 25.0%). The rate of admissions did not differ significantly by age(age 15-39 years, 40.0%;40-65 years, 25.0%;>65 years, 35.0%). Initial value of oxyhemoglobin saturation(SpO_2) measured by pulse oximetry was significantly lower in the admission group(SpO_2 92.4%)than in the nonadmissiongroup(SpO_2 95.2%, p<0.01).Conclusion:Patients with step 1 severity who visit an emergency unit with exacerbation of asthma may need regular treatment for asthma. When initial SpO_2 is less than 92%, we should consider hospitalization for treatment of asthma

Latrunculin A treatment prevents abnormal chromosome segregation for successful development of cloned embryos.

Somatic cell nuclear transfer to an enucleated oocyte is used for reprogramming somatic cells with the aim of achieving totipotency, but most cloned embryos die in the uterus after transfer. While modifying epigenetic states of cloned embryos can improve their development, the production rate of cloned embryos can also be enhanced by changing other factors. It has already been shown that abnormal chromosome segregation (ACS) is a major cause of the developmental failure of cloned embryos and that Latrunculin A (LatA), an actin polymerization inhibitor, improves F-actin formation and birth rate of cloned embryos. Since F-actin is important for chromosome congression in embryos, here we examined the relation between ACS and F-actin in cloned embryos. Using LatA treatment, the occurrence of ACS decreased significantly whereas cloned embryo-specific epigenetic abnormalities such as dimethylation of histone H3 at lysine 9 (H3K9me2) could not be corrected. In contrast, when H3K9me2 was normalized using the G9a histone methyltransferase inhibitor BIX-01294, the Magea2 gene-essential for normal development but never before expressed in cloned embryos-was expressed. However, this did not increase the cloning success rate. Thus, non-epigenetic factors also play an important role in determining the efficiency of mouse cloning

Abnormalities in placentae derived from cloned embryos.

<p>(A) Placental weights from ICSI-derived control embryos and CB- or LatA-treated cloned embryos. Error bars indicate SD. Asterisks indicate significant difference at p < 0.05. (B) Hematoxylin and eosin staining of placentae derived from ICSI-derived control and CB- or LatA-treated cloned embryos. Abnormal distortion of the boundary between the spongiotrophoblast and labyrinth layers was observed in placentas derived from both CB- and LatA-treated cloned embryos. Bar = 500 μm.</p

Histone modifications in 1-cell stage embryos.

<p>(A-D) acH3K9, acH3K14, H3K9me2 or H3K4me2 levels in ICSI-generated and CB- or LatA-treated cloned embryos. Bar = 30 µm. (E) The intensities of immunofluorescence for acH3K9, acH3K14, H3K9me2 and H3K4me2 relative to that of H2B. They are compared with the intensities in ICSI-generated control embryos. The acetylation or methylation levels of these regions were not different between LatA- and CB-treated cloned embryos.</p

Chromosome segregation in early embryonic development.

<p>(A) Chromosomes were misaligned at metaphase and lagging chromosomes were found at anaphase in embryos ACS was occured. (B-D) Merged and bright field images of embryos with normal chromosomal segregation (NCS) and abnormal chromosomal segregation (ACS). As an example, time-lapse images of chromosome segregation at the first, second and third mitosis are shown at the 2-cell, 4-cell and 8-cell stages, respectively. Arrows indicate chromosomal fragments appearing during the division. Green, EGFP-α-tubulin; red, mRFP–H2B. Bar = 30 µm. (E) The percentages of embryos with ACS at the 2-cell, 4-cell and 8-cell stages in ICSI-generated and cloned embryos. Values with different superscripts in the same category differ significantly between ICSI-generated, CB- and LatA-treated cloned embryos.</p

Band-Gap Deformation Potential and Elasticity Limit of Semiconductor Free-Standing Nanorods Characterized <i>in Situ</i> by Scanning Electron Microscope–Cathodoluminescence Nanospectroscopy

Modern field-effect transistors or laser diodes take advantages of band-edge structures engineered by large uniaxial strain ε_<i>zz</i>, available up to an elasticity limit at a rate of band-gap deformation potential <i>a</i>_<i>zz</i> (= d<i>E</i>_g/dε_<i>zz</i>). However, contrary to <i>a</i>_P values under hydrostatic pressure, there is no quantitative consensus on <i>a</i>_<i>zz</i> values under uniaxial tensile, compressive, and bending stress. This makes band-edge engineering inefficient. Here we propose SEM–cathodoluminescence nanospectroscopy under <i>in situ</i> nanomanipulation (Nanoprobe-CL). An apex of a <i>c</i>-axis-oriented free-standing ZnO nanorod (NR) is deflected by point-loading of bending stress, where local uniaxial strain (ε_<i>cc</i> = <i>r</i>/<i>R</i>) and its gradient across a NR (d<i>ε</i>_<i>cc</i>/d<i>r</i> = <i>R</i>^–1) are controlled by a NR local curvature (<i>R</i>^–1). The NR elasticity limit is evaluated sequentially (ε_<i>cc</i> = 0.04) from SEM observation of a NR bending deformation cycle. An electron beam is focused on several spots crossing a bent NR, and at each spot the local <i>E</i>_g is evaluated from near-band-edge CL emission energy. Uniaxial <i>a</i>_<i>cc</i> (= d<i>E</i>_g/dε_<i>cc</i>) is evaluated at regulated surface depth, and the impact of <i>R</i>^–1 on observed <i>a</i>_<i>cc</i> is investigated. The <i>a</i>_<i>cc</i> converges with −1.7 eV to the <i>R</i>^–1 = 0 limit, whereas it quenches with increasing <i>R</i>^–1, which is attributed to free-exciton drift under transversal band-gap gradient. Surface-sensitive CL measurements suggest that a discrepancy from bulk <i>a</i>_<i>cc</i> = −4 eV may originate from strain relaxation at the side surface under uniaxial stress. The nanoprobe-CL technique reveals an <i>E</i>_g(ε_<i>ij</i>) response to specific strain tensor ε_<i>ij</i> (<i>i</i>, <i>j</i> = <i>x</i>, <i>y</i>, <i>z</i>) and strain-gradient effects on a minority carrier population, enabling simulations and strain-dependent measurements of nanodevices with various structures