ZrB2–SiC–G Composite Prepared by Spark Plasma Sintering of In-Situ Synthesized ZrB2–SiC–C Composite Powders

To avoid introduction of milling media during ball-milling process and ensure uniform distribution of SiC and graphite in ZrB2 matrix, ultrafine ZrB2–SiC–C composite powders were in-situ synthesized using inorganic–organic hybrid precursors of Zr(OPr)4, Si(OC2H5)4, H3BO3, and excessive C6H14O6 as source of zirconium, silicon, boron, and carbon, respectively. To inhabit grain growth, the ZrB2–SiC–C composite powders were densified by spark plasma sintering (SPS) at 1950°C for 10 min with the heating rate of 100°C/min. The precursor powders were investigated by thermogravimetric analysis–differential scanning calorimetry and Fourier transform infrared spectroscopy. The ceramic powders were analyzed by X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. The lamellar substance was found and determined as graphite nanosheet by scanning electron microscopy, Raman spectrum, and X-ray diffraction. The SiC grains and graphite nanosheets distributed in ZrB2 matrix uniformly and the grain sizes of ZrB2 and SiC were about 5 lm and 2 lm, respectively. The carbon converted into graphite nanosheets under high temperature during the process of SPS. The presence of graphite nanosheets alters the load-displacement curves in the fracture process of ZrB2–SiC–G composite. A novel way was explored to prepare ZrB2–SiC–G composite by SPS of in-situ synthesized ZrB2–SiC–C composite powders.

Bioenabled SERS Substrates for Food Safety and Drinking Water Monitoring

We present low-cost bioenabled surface-enhanced Raman scattering (SERS) substrates that can be massively produced in sustainable and eco-friendly methods with significant commercial potentials for the detection of food contamination and drinking water pollution. The sensors are based on diatom frustules with integrated plasmonic nanoparticles. The ultra-high sensitivity of the SERS substrates comes from the coupling between the diatom frustules and Ag nanoparticles to achieve dramatically increased local optical field to enhance the light-matter interactions for SERS sensing. We successfully applied the bioenabled SERS substrates to detect melamine in milk and aromatic compounds in water with sensitivity down to 1μg/L.

Ion beam induced cubic to monoclinic phase transformation of nanocrystalline yttria

Sol gel derived nanocrystalline yttria pellets are irradiated with 120 MeV Ag9+ ions for fluence in the range 1 1012–3 1013 ions cm 2. Pristine and irradiated samples are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. XRD pattern of pristine Y2O3 nanocrystal reveal cubic structure. A new XRD peak at 30.36 is observed in pellet irradiated with 1 1013 ions cm 2. The peak at 30.36 is corresponding to ?40 2? plane of monoclinic phase. The diffraction intensity of ?40 2? plane increases with Ag9+ ion fluence. Raman spectrum of pristine pellet show bands corresponding to cubic phase. And, ion irradiated sample show new peaks at 410, 514 and 641 cm 1 corresponding monoclinic phase. HR-TEM and SAED pattern of ion irradiated sample confirmed the presence of monoclinic phase. Hence, it is confirmed that, 120 MeV Ag9+ ions induce phase transformation in nanocrystalline Y2O3.

?Infrared and Raman spectroscopy on synthetic glasses as analogues of planetary surfaces.

One of the fundamental aims of space mission is to understand the physical, chemical, and geologic processes and conditions of planetary formation and evolution. For this purpose, it is important to investigate analog material to correctly interpret the returned spacecraft data, including the spectral information from remote planetary surfaces. For example, mid-infrared spectroscopy provides detailed information on the mineralogical compositions of planetary surfaces via remote sensing. Data is affected by numerous factors such as grain size, illumination geometry, space weathering, and temperature. These features need to be systematically investigated on analog material in terrestrial laboratories in order to understand the mineralogy/composition of a planetary surface. In addition, Raman spectroscopy allows non-destructive analyses of planetary surfaces in the case of a landing mission.

Rapid isolation and detection of erythropoietin in blood plasma by magnetic core gold nanoparticles and portable Raman spectroscopy

Isolating, purifying, and identifying proteins in complex biological matrices are often difficult, time consuming, and unreliable. Herein we describe a rapid screening technique for proteins in biological matrices that combines selective protein isolation with direct surface enhanced Raman spectroscopy (SERS) detection. Magnetic core gold nanoparticles were synthesized, characterized, and subsequently functionalized with recombinant human erythropoietin (rHuEPO)-specific antibody. The functionalized nanoparticles were used to capture rHuEPO from horse blood plasma within 15 min. The selective binding between the protein and the functionalized nanoparticles was monitored by SERS. The purified protein was then released from the nanoparticles’ surface and directly spectroscopically identified on a commercial nanopillar SERS substrate. ELISA independently confirmed the SERS identification and quantified the released rHuEPO. Finally, the direct SERS detection of the extracted protein was successfully demonstrated for in-field screening by a handheld Raman spectrometer within 1 min sample measurement time.

?Raman microspectrometer combined with scattering microscopy and lensless imaging for bacteria identification

In this paper, we report on a compact prototype capable both of lensfree imaging, Raman spectrometry and scattering microscopy from bacteria samples. This instrument allows high-throughput real-time characterization without the need of markers, making it potentially suitable to field label-free biomedical and environmental applications.

Spectral fiber sensors for cancer diagnostics in vitro

Cancer is one of the leading causes for morbidity and mortality worldwide. Therefore, efforts are concentrated on cancer detection in an early stage to enhance survival rates for cancer patients. A certain intraoperative navigation in the tumor border zone is also an essential task to lower the mortality rate after surgical treatment. Molecular spectroscopy methods proved to be powerful tools to differentiate cancerous and healthy tissue. Within our project comparison of different vibration spectroscopy methods were tested to select the better one or to reach synergy from their combination. One key aspect was in special fiber probe development for each technique. Using fiber optic probes in Raman, MIR and NIR spectroscopy is a very powerful method for non-invasive in vivo applications. Miniaturization of Raman probes was achieved by deposition of dielectric filters directly onto the silica fiber end surfaces. Raman, NIR and MIR spectroscopy were used to analyze samples from kidney tumors. The differentiation between cancer and healthy samples was successfully obtained by multivariate data analysis.

A shifted-excitation Raman difference spectroscopy (SERDS) evaluation strategy for the efficient isolation of Raman spectra from extreme fluorescence interference

A biochemical characterization of pathologies in biological tissue can be provided by Raman spectroscopy. Often, the raw spectrum is severely affected by fluorescence interference. We report and compare various spectra-processing approaches required for the purification of Raman spectra from heavily fluorescence-interfered raw spectra according to the shifted-excitation Raman difference spectroscopy method. These approaches cover the entire spectra-processing chain fromthe raw spectra to the purified Raman spectra. In detail, we compared (1) area normalization versus z-score normalization, (2) direct reconstruction of the difference spectra versus reconstruction of zero-centered difference spectra and (3) collective baseline correction of the reconstructed spectra versus piecewise baseline correction of the reconstructed spectra and, finally, (4) analyzed the influence of the shift of the excitation wavelength on the quality of the reconstructed spectra. Statistical analysis of the spectra showed that – in our experiments – the best results were obtained for the z-score normalization before subtraction of the normalized spectra, followed by zero-centering of the difference spectra before reconstruction and a piecewise baseline correction of the pure Raman spectra.With our equipment, a wavelength shift from 784 to 785 nm provided reconstructed spectra of best quality. The analyzed specimens were different tissue types of pigs, tissue from the oral cavity of humans and a model solution of dye dissolved in ethanol.

Light quality modifies camptothecin production and gene expression of biosynthesis in Camptotheca acuminata Decne seedlings

The responses of plant growth and secondary metabolites to light quality are useful measurements to determine suitable habitat conditions for the cultivation of medicinal plants. The effect of light quality (white, blue, yellow, and red light) on leaf growth, camptothecin yield, the enzymatic activity, and the expression of camptothecin biosynthesis-related genes were investigated in Camptotheca acuminata seedlings. This was accomplished via measuring total leaf biomass, camptothecin content, activities of TSB and TDC, and the relative expression of TSB, TDC1, and TDC2 genes. Compared with white light, the red light treatment displayed the highest leaf biomass, while yellow light and blue light inhibited the growth of the plants. The lowest leaf biomass was found in plants under the blue light treatment. On day 45, the highest values of CPT content were observed under blue light conditions, followed by yellow light, red light, and white light. Among the four light environments, camptothecin yield was the highest in plants grown under red light. Furthermore, activities of TSB and TDC as well as the relative expression of genes of TSB, TDC1, and TDC2 were significantly increased on day 45 under blue light as compared with the white light. This suggests that blue light up-regulated the expression of camptothecin biosynthesisrelated genes and induced camptothecin biosynthesis. The results indicate that red light was effective for inducing the production of camptothecin in C. acuminata seedling leaves. Manipulating light quality can be an effective means to achieve the highest camptothecin yield in medicinal plantation, but this conclusion needs to be further verified by more well-designed large-scale trials.

?鉆石顏色分級(jí)的定量探討

鉆石的顏色是鉆石質(zhì)量評(píng)價(jià)4C(顏色color,凈度clarity,切工cut,重量carat)的重要標(biāo)準(zhǔn)之一。目前鉆石的顏色分級(jí)仍然依靠經(jīng)驗(yàn)豐富的專(zhuān)業(yè)人士,利用人眼對(duì)顏色的分辨率或市場(chǎng)上鉆石分級(jí)比色石來(lái)進(jìn)行。但此種方法帶有主觀性。為了將鉆石顏色分級(jí)工作變得客觀、準(zhǔn)確,應(yīng)用色度學(xué)CIE1931系統(tǒng),主要通過(guò)海洋公司生產(chǎn)的USB4000光纖光譜儀對(duì)I—MN色級(jí)共55顆鉆石進(jìn)行測(cè)試,將寶石顏色量化來(lái)探討鉆石顏色測(cè)試的可行性。實(shí)驗(yàn)表明,運(yùn)用色度學(xué)原理,不同色級(jí)鉆石的參數(shù)具有一定的規(guī)律,建立將鉆石顏色量化的體系,將不同色級(jí)鉆石的顏色進(jìn)行量化,并運(yùn)用到實(shí)際分級(jí)工作中具有一定的可行性。