Phase stability and the interface structure of a nanoscale Si crystallite in Al-based alloys.

An atomic-scale understanding of the role of strain on the microstructural properties of nanoscale precipitates will be helpful to explore the precipitation behavior as well as the structure-property relationships in crystalline multi-phase systems. Nanoscale Si precipitates are formed in Al-based alloys prepared by selective laser melting. The phase structure and the nature of heterointerface have been characterized using advanced electron microscopy. The nanocrystalline Si mainly contains two polymorphs, diamond-cubic Si (DC-Si) and 4H hexagonal Si (4H-Si). Heteroepitaxy occurs at the DC-Si(111)/Al(100) and 4H-Si(0001)/Al(100) interfaces in terms of a coincidence-site lattice model. The nanocrystalline Si undertakes tensile strain superposed by the matrix through heterointerfaces, facilitating the formation of 4H-Si in the nanoscale crystallite, which provides a strategy for designing Si polymorphic materials by strain engineering.

Growth hormone reverses dyslipidemia in adult offspring after maternal undernutrition.

The abnormal intrauterine milieu of fetal growth retardation could lead to dyslipidemia in adulthood. Studies have shown that growth hormone (GH) therapy in small for gestational age (SGA) children would be beneficial for metabolic parameters. Here we investigated whether GH treatment introduced at adolescent period in SGA could reverse dyslipidemia during later life. SGA rat model was established by using semi-starvation treatment during the whole pregnancy. SGA or appropriate for gestational age (AGA) offspring were assigned to receive GH or normal saline (NS). Once-daily subcutaneous injections of GH were administered between 21-35 days of age. In adulthood, as compared to AGA, SGA showed: (1) decreased body weight and length; (2) increased serum triglycerides; (3) down-regulated hepatic AMPK-α1 but up-regulated SREBP-1c and ACC-1; (4) a significant reduction in histone H3 acetylation at the promoter of AMPK-α1. Exogenous GH administration led to a restoration of body weight and length and normalized serum triglycerides by reversing expression of AMPK-α1 and its targeted genes SREBP-1c and ACC-1, through increasing H3 acetylation at the promoter of AMPK-α1 in SGA in adult period. These results demonstrated positive effects on lipid metabolism by a short treatment course of GH in SGA adult period.

Nanostructure Formation by controlled dewetting on patterned substrates: A combined theoretical, modeling and experimental study.

We perform systematic two-dimensional energetic analysis to study the stability of various nanostructures formed by dewetting solid films deposited on patterned substrates. Our analytical results show that by controlling system parameters such as the substrate surface pattern, film thickness and wetting angle, a variety of equilibrium nanostructures can be obtained. Phase diagrams are presented to show the complex relations between these system parameters and various nanostructure morphologies. We further carry out both phase field simulations and dewetting experiments to validate the analytically derived phase diagrams. Good agreements between the results from our energetic analyses and those from our phase field simulations and experiments verify our analysis. Hence, the phase diagrams presented here provide guidelines for using solid-state dewetting as a tool to achieve various nanostructures.

Maternal undernutrition leads to elevated hepatic triglycerides in male rat offspring due to increased expression of lipoprotein lipase.

Small for gestational age (SGA) at birth increases the risk of developing metabolic syndrome, which encompasses various symptoms including hypertriglyceridemia. The aim of the present study was to determine whether maternal undernutrition during pregnancy may lead to alterations in hepatic triglyceride content and the gene expression levels of hepatic lipoprotein lipase (LPL) in SGA male offspring. The present study focused on the male offspring in order to prevent confounding factors, such as estrus cycle and hormone profile. Female Sprague Dawley rats were arbitrarily assigned to receive an ad libitum chow diet or 50% food restricted diet from pregnancy day 1 until parturition. Reverse transcription quantitative polymerase chain reaction and western blot analysis were used to measure the gene expression levels of hepatic LPL at day 1 and upon completion of the third week of age. Chromatin immunoprecipitation quantified the binding activity of liver X receptor­α (LXR­α) gene to the LXR response elements (LXRE) on LPL promoter and LPL epigenetic characteristics. At 3 weeks of age, SGA male offspring exhibited significantly elevated levels of hepatic triglycerides, which was concomitant with increased expression levels of LPL. Since LPL is regulated by LXR­α, the expression levels of LXR­α were detected in appropriate for gestational age and SGA male offspring. Maternal undernutrition during pregnancy led to an increase in the hepatic expression levels of LXR­α, and enriched binding to the putative LXR response elements in the LPL promoter regions in 3­week­old male offspring. In addition, enhanced acetylation of histone H3 [H3 lysine (K)9 and H3K14] was detected surrounding the LPL promoter. The results of the present study indicated that maternal undernutrition during pregnancy may lead to an increase in hepatic triglycerides, via alterations in the transcriptional and epigenetic regulation of the LPL gene.

Fish oil improves lipid profile in juvenile rats with intrauterine growth retardation by altering the transcriptional expression of lipid-related hepatic genes.

OBJECTIVE: To determine whether maternal intrauterine undernutrition and post-weaning fish oil intake influence lipid profile in juvenile offspring, and explore the possible mechanisms at transcriptional levels. METHODS: After weaning, 32 control offspring and 24 intrauterine growth retardation (IUGR) offspring were randomly allocated to standard chow or fish oil diet. At 10 weeks, fasting plasma glucose, triglycerides, total cholesterol and expressions of related hepatic genes were examined. RESULTS: IUGR offspring without catch-up growth tended to develop hyperglycemia, dyslipidemia and hepatic steatosis. Down-regulation of CPT-1 and LDLR at transcriptional levels were found in IUGR offspring. Early short-term fish oil intervention reversed these unfavorable changes in juvenile rats with IUGR. The mechanisms might be mediated by decreased expression of ACC-1, increased expression of CPT-1, LDLR and ABCG5. CONCLUSION: These data suggest that IUGR offspring already present lipid abnormality in juvenile stage, and early short-term fish oil consumption is beneficial to prevent these unfavorable changes.

[Effects of intrauterine growth restriction and high-fat diet on serum lipid and transcriptional levels of related hepatic genes in rats].

OBJECTIVE: To study the effects of intrauterine growth restriction (IUGR) and high-fat diet on the growth, lipid metabolism, and related hepatic genes in rat offspring. METHODS: The rat model of IUGR was established by food restriction during the entire pregnancy. After weaning, 32 normal rats and 24 offspring rats with IUGR were randomly allocated to standard diet group or high-fat diet group. At the age of 10 weeks, fasting plasma glucose and blood lipid were examined. Additionally, pathological sections for hepatic tissues were observed, and the transcriptional levels of related hepatic genes were measured. RESULTS: At the age of 10 weeks, there was a significant difference in body weight between IUGR rats and normal rats on standard diets, but no significant difference in body weight was observed between the two groups on high-fat diets. Compared with the normal rats, IUGR rats showed increased energy intake and increased levels of fasting plasma glucose, total cholesterol, and triglyceride on both standard and high-fat diets. High-fat diets reduced the concentration of serum triglyceride in both normal rats and IUGR rats. IUGR and high-fat diets aggravated the fat accumulation in the liver. Two-factor analysis of variance showed that at the age of 10 weeks, the expression of genes related to lipid metabolism in the liver, PGC-1α, CPT-1, SREBF-2, HMGR, LDLR and SREBF-1, differed significantly between IUGR and normal rats. Compared with standard diets, high-fat diets increased the expression of PPARα, SREBF-1, SREBF-2, ABCG5, and CYP7A1 in both normal rats and IUGR rats. IUGR and high-fat diets had an interactive effect on LDLR expression. CONCLUSIONS: Hyperlipidemia and fat accumulation in the liver observed in IUGR rats may be related to increased appetite and regulation disorder in genes related to fatty acid oxidation at the transcriptional level. High-fat diets may aggravate fat accumulation in the liver in rats, which may be related to increased expression of genes related to regulation of fatty acid synthesis at the transcriptional level and reduction in secretion of triglyceride.

Second-Harmonic Generation from Sub-5 nm Gaps by Directed Self-Assembly of Nanoparticles onto Template-Stripped Gold Substrates.

Strong field enhancement and confinement in plasmonic nanostructures provide suitable conditions for nonlinear optics in ultracompact dimensions. Despite these enhancements, second-harmonic generation (SHG) is still inefficient due to the centrosymmetric crystal structure of the bulk metals used, e.g., Au and Ag. Taking advantage of symmetry breaking at the metal surface, one could greatly enhance SHG by engineering these metal surfaces in regions where the strong electric fields are localized. Here, we combine top-down lithography and bottom-up self-assembly to lodge single rows of 8 nm diameter Au nanoparticles into trenches in a Au film. The resultant "double gap" structures increase the surface-to-volume ratio of Au colocated with the strong fields in ∼2 nm gaps to fully exploit the surface SHG of Au. Compared to a densely packed arrangement of AuNPs on a smooth Au film, the double gaps enhance SHG emission by 4200-fold to achieve an effective second-order susceptibility χ((2)) of 6.1 pm/V, making it comparable with typical nonlinear crystals. This patterning approach also allows for the scalable fabrication of smooth gold surfaces with sub-5 nm gaps and presents opportunities for optical frequency up-conversion in applications that require extreme miniaturization.

Dynamically configurable hybridization of plasmon modes in nanoring dimer arrays.

We present a novel strategy capable of dynamically configuring the plasmon-induced transparency (PIT) effect with a polarization-dependent controllability based on a nanoring dimer array. The controllable coupling strength between the superradiant and subradiant modes is due to the polarization-dependent field distributions. It is shown that this dynamically controlled PIT is realized with a modulation depth as high as 95%, and a linear dependence of the coupling strength on polarization angle is deduced using a coupled-oscillator model. We believe that our results will inspire further exciting achievements that utilize various polarization states of the electromagnetic wave and pave a way towards applications using PIT with dynamic controllability such as slow light, optical nonlinearities and chemical/bio-sensing.

High aspect ratio 10-nm-scale nanoaperture arrays with template-guided metal dewetting.

We introduce an approach to fabricate ordered arrays of 10-nm-scale silica-filled apertures in a metal film without etching or liftoff. Using low temperature (<400°C) thermal dewetting of metal films guided by nano-patterned templates, apertures with aspect ratios up to 5:1 are demonstrated. Apertures form spontaneously during the thermal process without need for further processing. Although the phenomenon of dewetting has been well studied, this is the first demonstration of its use in the fabrication of nanoapertures in a spatially controllable manner. In particular, the achievement of 10-nm length-scale patterning at high aspect ratio with thermal dewetting is unprecedented. By varying the nanotemplate design, we show its strong influence over the positions and sizes of the nanoapertures. In addition, we construct a three-dimensional phase field model of metal dewetting on nano-patterned substrates. The simulation data obtained closely corroborates our experimental results and reveals new insights to template dewetting at the nanoscale. Taken together, this fabrication method and simulation model form a complete toolbox for 10-nm-scale patterning using template-guided dewetting that could be extended to a wide range of material systems and geometries.

Microscopy illumination engineering using a low-cost liquid crystal display.

Illumination engineering is critical for obtaining high-resolution, high-quality images in microscope settings. In a typical microscope, the condenser lens provides sample illumination that is uniform and free from glare. The associated condenser diaphragm can be manually adjusted to obtain the optimal illumination numerical aperture. In this paper, we report a programmable condenser lens for active illumination control. In our prototype setup, we used a $15 liquid crystal display as a transparent spatial light modulator and placed it at the back focal plane of the condenser lens. By setting different binary patterns on the display, we can actively control the illumination and the spatial coherence of the microscope platform. We demonstrated the use of such a simple scheme for multimodal imaging, including bright-field microscopy, darkfield microscopy, phase-contrast microscopy, polarization microscopy, 3D tomographic imaging, and super-resolution Fourier ptychographic imaging. The reported illumination engineering scheme is cost-effective and compatible with most existing platforms. It enables a turnkey solution with high flexibility for researchers in various communities. From the engineering point-of-view, the reported illumination scheme may also provide new insights for the development of multimodal microscopy and Fourier ptychographic imaging.

Plasmonic color palettes for photorealistic printing with aluminum nanostructures.

We introduce the first plasmonic palette utilizing color generation strategies for photorealistic printing with aluminum nanostructures. Our work expands the visible color space through spatially mixing and adjusting the nanoscale spacing of discrete nanostructures. With aluminum as the plasmonic material, we achieved enhanced durability and dramatically reduced materials costs with our nanostructures compared to commonly used plasmonic materials such as gold and silver, as well as size regimes scalable to higher-throughput approaches such as photolithography and nanoimprint lithography. These advances could pave the way toward a new generation of low-cost, high-resolution, plasmonic color printing with direct applications in security tagging, cryptography, and information storage.

Speckle-scale focusing in the diffusive regime with time-reversal of variance-encoded light (TROVE).

Focusing of light in the diffusive regime inside scattering media has long been considered impossible. Recently, this limitation has been overcome with time reversal of ultrasound-encoded light (TRUE), but the resolution of this approach is fundamentally limited by the large number of optical modes within the ultrasound focus. Here, we introduce a new approach, time reversal of variance-encoded light (TROVE), which demixes these spatial modes by variance-encoding to break the resolution barrier imposed by the ultrasound. By encoding individual spatial modes inside the scattering sample with unique variances, we effectively uncouple the system resolution from the size of the ultrasound focus. This enables us to demonstrate optical focusing and imaging with diffuse light at unprecedented, speckle-scale lateral resolution of ~ 5 µm.

[A clinical follow-up study of premature thelarche in infants under two years of age].

OBJECTIVE: To investigate the clinical status and natural course of premature thelarche (PT) in infants under 2 years of age and to analyze the predictive factors for regression of thelarche. METHODS: The clinical and laboratory data of 863 infants under 2 years of age, who visited the department of endocrinology in our hospital due to PT between October 2009 and September 2010, were analyzed. A a longitudinal follow-up study was performed. RESULTS: Of the infants under 2 years of age with isolated PT, 89.3% showed a regression before the age of 3 years (mean 17±5.6 months), 10.7% had recurrent or persistent thelarche, with no regression after the age of 3 years, and some even developed into central precocious puberty. The independent predictive factors for regression of thelarche were Tanner stage at the first visit and whether baseline estradiol level had increased. CONCLUSIONS: PT in infants under 2 years of age is not rare in the clinical setting, and it usually runs a self-limited course, subsiding before the age of 3 years. However, regular follow-ups should be performed for infants aged over 2 years with persistent thelarche.

Deep-tissue focal fluorescence imaging with digitally time-reversed ultrasound-encoded light.

Fluorescence imaging is one of the most important research tools in biomedical sciences. However, scattering of light severely impedes imaging of thick biological samples beyond the ballistic regime. Here we directly show focusing and high-resolution fluorescence imaging deep inside biological tissues by digitally time-reversing ultrasound-tagged light with high optical gain (~5×10(5)). We confirm the presence of a time-reversed optical focus along with a diffuse background-a corollary of partial phase conjugation-and develop an approach for dynamic background cancellation. To illustrate the potential of our method, we image complex fluorescent objects and tumour microtissues at an unprecedented depth of 2.5 mm in biological tissues at a lateral resolution of 36 µm×52 µm and an axial resolution of 657 µm. Our results set the stage for a range of deep-tissue imaging applications in biomedical research and medical diagnostics.

Wide field-of-view microscope based on holographic focus grid illumination.

We have developed a new microscopy design that can achieve wide field-of-view (FOV) imaging and yet possesses resolution that is comparable to a conventional microscope. In our design, the sample is illuminated by a holographically projected light-spot grid. We acquire images by translating the sample across the grid and detecting the transmissions. We have built a prototype system with an FOV of 6 mm x 5 mm and acquisition time of 2.5 s. The resolution is fundamentally limited by the spot size--our demonstrated average FWHM spot diameter was 0.74 microm. We demonstrate the prototype by imaging a U.S. Air Force target and a lily anther. This technology is scalable and represents a cost-effective way to implement wide FOV microscopy systems.

Implementation of a color-capable optofluidic microscope on a RGB CMOS color sensor chip substrate.

We report the implementation of a color-capable on-chip lensless microscope system, termed color optofluidic microscope (color OFM), and demonstrate imaging of double stained Caenorhabditis elegans with lacZ gene expression at a light intensity about 10 mW/cm(2).

Characterization of acceptance angles of small circular apertures.

We characterize the acceptance angles of small circular apertures for light collection by simulations and experimental measurements. By examining the full width half maximum acceptance angle as a function of the aperture size, we show that the acceptance angle of a circular aperture reaches a minimum of 67 deg before rebounding around the transition between single mode and multimode transmission (approximately 400 nm). This behavior can be explained by the change of mode-coupling efficiency during the transition from single mode to multimode propagation regime. This work in understanding of the behavior of light transmission through subwavelength apertures will guide the design of better aperture based imaging devices where apertures are used as light collection units.

[The significance of volumetric capnography in assessment of asthmatic acute exacerbation staging].

OBJECTIVE: To investigate the diagnostic value of volumetric capnography in the assessment of asthmatic exacerbation. METHODS: Sixty-four patients with asthma exacerbation and 20 normal controls performed spirometry and volumetric capnography recording. The patients with asthma were divided into three sub-groups according to FEV1% pred (A: > 80%, B:40% - 80%, C: < 40%). RESULTS: FEV1% pred, FEV1/FVC, PEF% pred and MMEF% pred were (98 +/- 9)%, (80 +/- 6)%, (91 +/-15)% and (73 +/- 7)% respectively in the control group, but were (52 +/- 20)%, (50 +/- 10)%, (49 +/-16)% and (28 +/- 16)% respectively in the asthma group, the difference being significant (t = 6.93 - 13.29, all P < 0.01). Compared with the control group, dC2/DV [(19 +/- 6)%/L vs (31 +/- 8)%/L, t = 5. 09, P < 0.01] showed a decrease in the asthma group, dC3/DV [(2.9 +/- 1.2)%/L vs (1.0 +/- 0.4)%/L, t = -6. 14, P < 0.01] and SR23 [(16.8 +/- 10.6)% vs (3.3 +/-1.5)%, t = -6.54, P < 0.01] showed an increase in the asthma group compared to the control group, the difference being significant. Compared with that of the control group, dC2/DV [B:(17 +/-5)%/L, C: (13 +/-4)%/L] showed a decrease (t = -11.82, -16.75, all P < 0.01) and dC3/DV [B:(3.2 +/- 0.8)%/L, C:(4.1 +/-1.2)%/L] and SR23 [B:(17.2 +/- 3.5)%, C:(28.3 +/- 6.9)%] showed an increase (t = 2. 16-26.08, all P < 0.01) in asthma sub-groups B and C. For dC3/DV and SR23, the difference was significant between asthma sub-groups (t = 0.91 -22.18, all P < 0.05). In Pearson correlation analysis, dC2/DV (r = 0.69, 0.54, 0.59, 0.54, all P < 0.01) and dC3/DV (r = -0.62, -0.45, -0.69, -0.58, all P < 0.01) and SR23 (r = -0.75, -0.52, -0.74, -0.62, all P < 0.01) correlated with FEV1% pred, FEV1/FVC, PEF% pred and MMEF% pred. CONCLUSION: Volumetric capnography is a quantitative method for evaluating the severity of airflow obstruction and it can be performed easily during tidal breathing.

Mid-term effects of lung volume reduction surgery on pulmonary function in patients with chronic obstructive pulmonary disease.

BACKGROUND: Now lung volume reduction surgery (LVRS) has become one of the most effective methods for the management of some cases of severe chronic obstructive pulmonary disease (COPD). We evaluated the mid-term effects of LVRS on pulmonary function in patients with severe COPD. METHODS: Ten male patients with severe COPD aged 38 - 70 years underwent LVRS and their pulmonary function was assessed before, 3 months and 3 years after surgery. The spirometric and gas exchange parameters included residual volume, total lung capacity, inspiratory capacity, forced vital capacity, forced expiratory volume in one second, diffusion capacity for CO, and arterial blood gas. A 6-minute walk distance (6MWD) test was performed. RESULTS: As to preoperative assessment, most spirometric parameters and 6MWD were significantly improved after 3 months and slightly 3 years after LVRS. Gas exchange parameters were significantly improved 3 months after surgery, but returned to the preoperative levels after 3 years. CONCLUSIONS: LVRS may significantly improve pulmonary function in patients with severe COPD indicating for LVRS. Mid-term pulmonary function 3 years after surgery can be decreased to the level at 3 months after surgery. Three years after LVRS, lung volume and pulmonary ventilation function can be significantly improved, but the improvement in gas exchange function was not significant.