scholarly journals Improving Sensitivity in Raman Imaging for Thin Layered and Powdered Food Analysis Utilizing a Reflection Mirror

Sensors ◽  
2019 ◽  
Vol 19 (12) ◽  
pp. 2698 ◽  
Author(s):  
Santosh Lohumi ◽  
Moon S. Kim ◽  
Jianwei Qin ◽  
Byoung-Kwan Cho
Keyword(s):  
Surface Layer ◽  
Deep Layer ◽  
Subsurface Layer ◽  
Thick Layer ◽  
Raman Imaging ◽  
Chemical Components ◽  
Raman Signal ◽  
Analytical Technique ◽  
Powdered Food ◽  
Pharmaceutical Industries

Raman imaging has been proven to be a powerful analytical technique for the characterization and visualization of chemical components in a range of products, particularly in the food and pharmaceutical industries. The conventional backscattering Raman imaging technique for the spatial analysis of a deep layer suffers from the presence of intense fluorescent and Raman signals originating from the surface layer which mask the weaker subsurface signals. Here, we demonstrated the application of a new reflection amplifying method using a background mirror as a sample holder to increase the Raman signals from a deep layer. The approach is conceptually demonstrated on enhancing the Raman signals from the subsurface layer. Results show that when bilayer samples are scanned on a reflection mirror, the average signals increase 1.62 times for the intense band at 476 cm−1 of starch powder, and average increases of 2.04 times (for the band at 672 cm−1) for a subsurface layer of high Raman sensitive melamine powder under a 1 mm thick teflon sheet. The method was then applied successfully to detect noninvasively the presence of small polystyrene pieces buried under a 2 mm thick layer of food powder (a case of powdered food adulteration) which otherwise are inaccessible to conventional backscattering Raman imaging. In addition, the increase in the Raman signal to noise ratio when measuring samples on a mirror is an important feature in many applications where high-throughput imaging is of interest. This concept is also applicable in an analogous manner to other disciplines, such as pharmaceutical where the Raman signals from deeper zones are typically, substantially diluted due to the interference from the surface layer.

Description of Work-Hardening Layer’s Depth by Soft Coefficient

2009 ◽  
Vol 419-420 ◽  
pp. 73-76
Author(s):  
Rong Chang Liu ◽  
Li Dong Chen ◽  
Yu Wu ◽  
Shu Ying Ma ◽  
Li Zhen Feng
Keyword(s):  
Surface Layer ◽  
Contact Problem ◽  
Work Hardening ◽  
Stress Condition ◽  
Deep Layer ◽  
Subsurface Layer ◽  
Quantitative Description ◽  
Contact Problems ◽  
Measuring Method ◽  
Element Analysis

In this paper, by introducing the conceptions of stress condition and soft coefficient, a nonlinear equation is used to describe stress condition of the contacting body along depth. By taking the classical contact problem of two parallel cylinders as an example, we give a quantitative description of work-hardening layer’s depth related to local contact problems by using soft coefficient, and it is theoretically proved that plastic deformation and plastic failure exist objectively in engineering contact problem. The analysis indicates that hardening layer’s depth in the range of 0.43643b(where “b” represents contacting semi-width ), where soft coefficient equivalents to infinity, can be defined as "work-hardening surface layer", depth ranging from 0.43643b to 3b can be roughly defined as "subsurface layer", and depth ranging out of 3b can be defined as "deep layer". Finite element analysis of Ono-rolling specimen shows that measuring method of x-ray of the residual stress is relatively more accurate in the surface layer; however, numerical method can give more accurate results than experimental method in the subsurface and deep layer.

scholarly journals Springtime Upwelling and Its Formation Mechanism in Coastal Waters of Manaung Island, Myanmar

2020 ◽  
Vol 12 (22) ◽  
pp. 3777
Author(s):  
Yuhui Li ◽  
Yun Qiu ◽  
Jianyu Hu ◽  
Cherry Aung ◽  
Xinyu Lin ◽  
...  
Keyword(s):  
Surface Layer ◽  
Satellite Remote Sensing ◽  
Subsurface Layer ◽  
World Ocean ◽  
Remote Sensing Data ◽  
Remote Forcing ◽  
Forcing Mechanisms ◽  
World Ocean Atlas ◽  
The Impact ◽  
Local Wind Forcing

Multisource satellite remote sensing data and the World Ocean Atlas 2018 (WOA18) temperature and salinity dataset have been used to analyze the spatial distribution, variability and possible forcing mechanisms of the upwelling off Manaung Island, Myanmar. Signals of upwelling exist off the coasts of Manaung Island, in western Myanmar during spring. It appears in February, reaches its peak in March and decays in May. Low-temperature (<28.3 °C) and high-salinity (>31.8 psu) water at the surface of this upwelling zone is caused by the upwelling of seawater from a depth below 100 m. The impact of the upwelling on temperature is more significant in the subsurface layer than that in the surface layer. In contrast, the impact of the upwelling on salinity in the surface layer is more significant. Further research reveals that the remote forcing from the equator predominantly induces the evolution of the upwelling, while the local wind forcing also contributes to strengthen the intensity of the upwelling during spring.

scholarly journals Chiral Selectors in Capillary Electrophoresis: Trends During 2017–2018

Molecules ◽  
2019 ◽  
Vol 24 (6) ◽  
pp. 1135 ◽  
Author(s):  
Raymond B. Yu ◽  
Joselito P. Quirino
Keyword(s):  
Capillary Electrophoresis ◽  
Molecular Mass ◽  
Chiral Separation ◽  
Chiral Separations ◽  
Water Soluble ◽  
Resonance Spectroscopy ◽  
Electrokinetic Chromatography ◽  
Chiral Selectors ◽  
Analytical Technique ◽  
Pharmaceutical Industries

Chiral separation is an important process in the chemical and pharmaceutical industries. From the analytical chemistry perspective, chiral separation is required for assessing the fit-for-purpose and the safety of chemical products. Capillary electrophoresis, in the electrokinetic chromatography mode is an established analytical technique for chiral separations. A water-soluble chiral selector is typically used. This review therefore examines the use of various chiral selectors in electrokinetic chromatography during 2017–2018. The chiral selectors were both low and high (macromolecules) molecular mass molecules as well as molecular aggregates (supramolecules). There were 58 papers found by search in Scopus, indicating continuous and active activity in this research area. The macromolecules were sugar-, amino acid-, and nucleic acid-based polymers. The supramolecules were bile salt micelles. The low molecular mass selectors were mainly ionic liquids and complexes with a central ion. A majority of the papers were on the use or preparation of sugar-based macromolecules, e.g., native or derivatised cyclodextrins. Studies to explain chiral recognition of macromolecular and supramolecular chiral selectors were mainly done by molecular modelling and nuclear magnetic resonance spectroscopy. Demonstrations were predominantly on drug analysis for the separation of racemates.

scholarly journals GC-MS Chemical Characterization of Main Components of Smilax Domingensis Wild. in Cuba

2018 ◽  
Vol 5 (4) ◽  
pp. 79 ◽  
Author(s):  
Pilar A. Soledispa ◽  
José González ◽  
Armando Cuéllar ◽  
Julio Pérez ◽  
Max Monan
Keyword(s):  
Mass Spectra ◽  
Chemical Constituents ◽  
Chemical Characterization ◽  
Ethanolic Extract ◽  
Chemical Compounds ◽  
Chemical Components ◽  
Analytical Technique ◽  
Main Components ◽  
First Time

A preliminary chemical characterization of main components of ethanolic extract with dried rhizomes of Smilax domingensis Wid. that grow in Cuba was done using a GCMS-QP2010 Ultra Shimadzu and the mass spectra of the compounds found in the extract was matched with the National Institute of Standards and Technology (NIST) library. After sample derivatization 125 chemical compounds were registered by the equipment and from them, 35 different chemical components were characterized and reported for the first time from this part of the plant in our country. The results demonstrate the developed method could be employed as a rapid and versatile analytical technique for identification of chemical constituents and quality control of Smilax domingensis.

Collagen organization in articular cartilage, determined by X-ray diffraction, and its relationship to tissue function

1981 ◽  
Vol 212 (1188) ◽  
pp. 299-304 ◽  
Keyword(s):  
Surface Layer ◽  
Deep Layer ◽  
Articular Surface ◽  
Swelling Pressure ◽  
Bimodal Distribution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Collagen Organization ◽  
Patellar Cartilage ◽  
Calcified Tissue

X-ray diffraction has been used to measure the preferred orientation of the collagen fibrils, and their angular distribution within the tissue, as a function of depth from the articular surface in patellar cartilage. Measurements have been made at four different sites chosen to represent differing surface curvatures and régimes of wear. The orientation of fibrils in the surface layer allows it to oppose the swelling pressure exerted by the gel of hydrated glycosaminoglycans within the cartilage. An intermediate layer (where a bimodal distribution of fibrils is sometimes resolved) allows the orientation of the fibrils to change, with increasing depth, until they are roughly perpendicular to the articular surface. In this deep layer the fibrils can tie into the underlying calcified tissue so as to firmly anchor the cartilage. In the plane of the surface the fibrils tend to be aligned in the direction of stress caused by motion.

scholarly journals Impact of Protists on the Activity and Structure of the Bacterial Community in a Rice Field Soil

2006 ◽  
Vol 72 (8) ◽  
pp. 5436-5444 ◽  
Author(s):  
Jun Murase ◽  
Matthias Noll ◽  
Peter Frenzel
Keyword(s):  
Surface Layer ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Subsurface Layer ◽  
Molecular Ecology ◽  
Rflp Analysis ◽  
Small Subunit ◽  
Rice Fields ◽  
Bacterial Assemblage ◽  
Protistan Grazing ◽  
The Impact

ABSTRACT Flooded rice fields have become a model system for the study of soil microbial ecology. In Italian rice fields, in particular, aspects from biogeochemistry to molecular ecology have been studied, but the impact of protistan grazing on the structure and function of the prokaryotic community has not been examined yet. We compared an untreated control soil with a γ-radiation-sterilized soil that had been reinoculated with a natural bacterial assemblage. In order to verify that the observed effects were due to protistan grazing and did not result from sterilization, we set up a third set of microcosms containing sterilized soil that had been reinoculated with natural assemblage bacteria plus protists. The spatial and temporal changes in the protistan and prokaryotic communities were examined by denaturing gradient gel electrophoresis (DGGE) and terminal restriction fragment length polymorphism (T-RFLP) analysis, respectively, both based on the small-subunit gene. Sequences retrieved from DGGE bands were preferentially affiliated with Cercozoa and other bacteriovorous flagellates. Without protists, the level of total DNA increased with incubation time, indicating that the level of the microbial biomass was elevated. Betaproteobacteria were preferentially preyed upon, while low-G+C-content gram-positive bacteria became more dominant under grazing pressure. The bacterial diversity detectable by T-RFLP analysis was greater in the presence of protists. The level of extractable NH4 + was lower and the level of extractable SO4 2− was higher without protists, indicating that nitrogen mineralization and SO4 2− reduction were stimulated by protists. Most of these effects were more obvious in the partially oxic surface layer (0 to 3 mm), but they could also be detected in the anoxic subsurface layer (10 to 13 mm). Our observations fit well into the overall framework developed for protistan grazing, but with some modifications pertinent to the wetland situation: O2 was a major control, and O2 availability may have limited directly and indirectly the development of protists. Although detectable in the lower anoxic layer, grazing effects were much more obvious in the partially oxic surface layer.

scholarly journals Soil chemical management drives structural degradation of Oxisols under a no-till cropping system

Soil Research ◽  
2017 ◽  
Vol 55 (8) ◽  
pp. 819 ◽  
Author(s):  
Márcio R. Nunes ◽  
Alvaro P. da Silva ◽  
José E. Denardin ◽  
Neyde F. B. Giarola ◽  
Carlos M. P. Vaz ◽  
...  
Keyword(s):  
Surface Layer ◽  
Structural Stability ◽  
Subsurface Layer ◽  
Structural Degradation ◽  
Chemical Management ◽  
No Till ◽  
Cultivated Soil ◽  
Water Percolation ◽  
Soil Structural Stability ◽  
Dispersible Clay

Physical degradation of the subsurface layer of soils reduces the effectiveness of no-till (NT) as a sustainable soil management approach in crop production. Chemical factors may reduce the structural stability of Oxisols and thereby exacerbate compaction from machinery traffic. We studied the relationship between chemical management and structural degradation in Oxisols cultivated under NT at three sites in southern Brazil. The surface and subsurface layers of the soils were characterised chemically and mineralogically and three physical attributes related to soil structural stability (readily dispersible clay in water, mechanically dispersible clay in water, and water percolation) were quantified for each layer. The same characterisations were performed on Oxisols collected from adjacent non-cultivated areas, to provide reference data for non-degraded soil. The levels of dispersed clay in the cultivated soil from the surface layer matched those of the non-cultivated soil, but for the subsurface layer higher dispersed clay levels in the cultivated soil showed that it was physically degraded relative to the non-cultivated soil. Water percolation was found to be slower through the Oxisols cultivated under NT, irrespective of the soil layer. The relationships between the three indicators of soil structural stability and the measured chemical and mineralogical variables of the soils were explored through an analysis of canonical correlation. The principal variables associated with the lower stability of the cultivated vs non-cultivated Oxisols were the lower concentrations of organic carbon and exchangeable aluminium and, for the surface layer, the higher pH. It is argued that structural degradation of Oxisols cultivated under NT, observed predominantly in the subsurface layer, has been aggravated by the accumulation of amendments and fertilisers in the surface soil and reduced levels of organic matter, especially in the subsurface layer.

scholarly journals Surface-Enhanced Raman Sensing of Semi-Volatile Organic Compounds by Plasmonic Nanostructures

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2619
Author(s):  
Nguyễn Hoàng Ly ◽  
Sang Jun Son ◽  
Soonmin Jang ◽  
Cheolmin Lee ◽  
Jung Il Lee ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Optical Sensors ◽  
Metal Nanostructures ◽  
Raman Signal ◽  
Plasmonic Nanostructures ◽  
Analytical Technique ◽  
Surface Enhanced ◽  
Volatile Organic ◽  
Surface Enhanced Raman

Facile detection of indoor semi-volatile organic compounds (SVOCs) is a critical issue to raise an increasing concern to current researchers, since their emissions have impacted the health of humans, who spend much of their time indoors after the recent incessant COVID-19 pandemic outbreaks. Plasmonic nanomaterial platforms can utilize an electromagnetic field to induce significant Raman signal enhancements of vibrational spectra of pollutant molecules from localized hotspots. Surface-enhanced Raman scattering (SERS) sensing based on functional plasmonic nanostructures has currently emerged as a powerful analytical technique, which is widely adopted for the ultra-sensitive detection of SVOC molecules, including phthalates and polycyclic aromatic hydrocarbons (PAHs) from household chemicals in indoor environments. This concise topical review gives updated recent developments and trends in optical sensors of surface plasmon resonance (SPR) and SERS for effective sensing of SVOCs by functionalization of noble metal nanostructures. Specific features of plasmonic nanomaterials utilized in sensors are evaluated comparatively, including their various sizes and shapes. Novel aptasensors-assisted SERS technology and its potential application are also introduced for selective sensing. The current challenges and perspectives on SERS-based optical sensors using plasmonic nanomaterial platforms and aptasensors are discussed for applying indoor SVOC detection.

scholarly journals Assessment of Skin Deep Layer Biochemical Profile Using Spatially Offset Raman Spectroscopy

2021 ◽  
Vol 11 (20) ◽  
pp. 9498
Author(s):  
Martha Z. Vardaki ◽  
Konstantinos Seretis ◽  
Georgios Gaitanis ◽  
Ioannis D. Bassukas ◽  
Nikolaos Kourkoumelis
Keyword(s):  
Raman Spectroscopy ◽  
Skin Cancer ◽  
Deep Layer ◽  
Signal To Noise Ratio ◽  
Skin Tissue ◽  
Raman Signal ◽  
Histopathological Analysis ◽  
Biochemical Profile ◽  
Skin Cancer Screening ◽  
Zero Offset

Skin cancer is currently the most common type of cancer with millions of cases diagnosed worldwide yearly. The current gold standard for clinical diagnosis of skin cancer is an invasive and relatively time-consuming procedure, consisting of visual examination followed by biopsy collection and histopathological analysis. Raman spectroscopy has been shown to efficiently aid the non-invasive diagnosis of skin cancer when probing the surface of the skin. In this study, we employ a recent development of Raman spectroscopy (Spatially Offset Raman Spectroscopy, SORS) which is able to look deeper in tissue and create a deep layer biochemical profile of the skin in areas where cancer lesions subtly evolve. After optimizing the measurement parameters on skin tissue phantoms, we then adopted SORS on human skin tissue from different anatomical areas to investigate the contribution of the different skin layers to the recorded Raman signal. Our results show that using a diffuse beam with zero offset to probe a sampling volume where the lesion is typically included (surface to epidermis-dermis junction), provides the optimum signal-to-noise ratio (SNR) and may be employed in future skin cancer screening applications.

Vertical flows of substance in the Northern arctic ocean

2021 ◽  
pp. 278-286
Author(s):  
A.N. Novigatsky ◽  
◽  
A.P. Lisitzin ◽  
V.P. Shevchenko ◽  
A.A. Klyuvitkin ◽  
...  
Keyword(s):  
Surface Layer ◽  
Arctic Ocean ◽  
Bottom Sediments ◽  
The Arctic ◽  
Chemical Components ◽  
Vertical Fluxes ◽  
Sedimentary Matter ◽  
The Arctic Ocean ◽  
Direct Calculations

The monthly, seasonal and annual quantity estimates of vertical fluxes of sedimentary matter from the surface layer of the Arctic Ocean, performed out over the years by various researchers, are the basis for direct calculations of incoming chemical components, minerals, and various pollutants to the surface layer of bottom sediments.

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