Monitoring Of HF/H2O Treated Silicon Surfaces Using Noncontact Surface Charge Measurements

1995 ◽  
Vol 386 ◽  
Author(s):  
P. Roman ◽  
D. Hwang ◽  
K. Torek ◽  
J. Ruzyllo ◽  
E. Kamieniecki
Keyword(s):  
Surface Charge ◽  
Silicon Surface ◽  
Positive Charge ◽  
Silicon Surfaces ◽  
Chemical Condition ◽  
Charged Species ◽  
Non Invasive ◽  
System A ◽  
Oxide Etching

ABSTRACTIn this work, a new commercial system allowing non-contact measurement of the surface charge is used to monitor the condition of the silicon surface following HF/water etch. Results obtained demonstrate that by monitoring changes of surface charge using this system, a truly non-invasive, instant and easy to carry out characterization of Si surfaces after HF/water etch can be accomplished. The results show that HF/water exposure adds positive charge to the silicon surface. Change in the surface charge, considered to be indicative of the change in the electro-chemical condition of the surface, appears to precede initiation of the oxide etching process, and is proposed to be a factor in initiating etching reactions that involve mainly negatively charged species.

Characterization of HF Treated (100) Si Surfaces by Surface Charge Analysis (SCA)

1992 ◽  
Vol 259 ◽  
Author(s):  
Jon T. Fitch
Keyword(s):  
Electrical Properties ◽  
Surface Charge ◽  
Chemical Bonding ◽  
Oxide Thickness ◽  
Silicon Surfaces ◽  
Native Oxide ◽  
Charge Analysis ◽  
The Stability ◽  
Over Time

ABSTRACTSurface Charge Analysis (SCA), and ellipsometry have been used to study the stability over time of HF treated (100) silicon surfaces as a function of the post-HF rinse time. Using SCA, the electrical properties of the chemical terminating layer of these silicon surfaces were measured. The surfaces which remained native oxide free the longest (−10 hours) had very low Qox and Dit values on the order of 1.0 × 1011/cm2 and 5.0 × 1010 eV−lcm−2, respectively. A good correlation was found between Dit and the native oxide thickness measured by ellipsometry. This and other results are discussed in terms of the chemical bonding on the silicon surfaces.

scholarly journals Comparative Characterization of Birch Bark Extracts Encapsulated Inside Polyurethane Microstructures

2018 ◽  
Vol 55 (3) ◽  
pp. 385-388 ◽  
Author(s):  
Florin Borcan ◽  
Marius Preda ◽  
Livia Cristina Borcan ◽  
Iulia Pinzaru ◽  
Sorin Florescu ◽  
...  
Keyword(s):  
Surface Charge ◽  
Birch Bark ◽  
Organosulfur Compounds ◽  
Dsc Analysis ◽  
Good Thermal Stability ◽  
Safe Delivery ◽  
Non Invasive ◽  
Natural Extracts ◽  
Invasive Techniques

The phytotherapy is based on the consume of fruits, vegetables and medicinal plants; they contain mixtures of bioactive chemical substances (carotenoids, phenolic acids, flavonoids, coumarins, tannins, organosulfur compounds) with synergic effects on the treatment of diseases. Nano- and micro-carriers are very useful drug delivery systems which can improve the transmembrane transfer of natural extracts. In the present study, betulin and two birch bark extracts were encapsulated inside polyurethane microstructures. Structures� size, homogeneity and surface charge were studied using a Zetasizer, while DSC analysis was involved to assay structures� thermal behavior. Irritation effects were monitored by non-invasive techniques on human skin. The results indicate the obtaining of structures with size around 200-250 nm, with a positive surface charge and a very good thermal stability. The non-irritation potential recommends these structures as a safe delivery system used for natural extracts.

Molecular Dynamics Simulation of Water and Ion Profiles Near Charged (100) and (111) Silicon Surfaces

2008 ◽  
Author(s):  
Dongyan Xu ◽  
Deyu Li ◽  
Yongsheng Leng ◽  
Yunfei Chen
Keyword(s):  
Molecular Dynamics ◽  
Charge Density ◽  
Surface Charge ◽  
Surface Charge Density ◽  
Silicon Surface ◽  
Silicon Surfaces ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Wall Region ◽  
Surface Charges

Fundamental studies in nanofluidics have attracted significant attention in the past decade since the success of nanofluidic devices depends on a thorough understanding of the fluidic, ionic, and molecular behaviors in highly confined nano-environments. In this work, molecular dynamics simulations of the effect of surface charge densities on the ion and water distribution in the near wall region has been performed for both (100) and (111) silicon surfaces. We demonstrate that surface charges not only interact with mobile ions in the electrolyte, but also interact with water molecules due to their polarizability and hence influence the orientation of water molecules close to the charged surface. It is shown that as the surface charge density increases, water molecules within ∼ 5 Å from the (100) silicon surface can evolve from one layer into two layers and meanwhile, the orientation of water molecules is more aligned instead of randomly distributed. However, no extra water layer is observed near a (111) silicon surface even under a surface charge density of as high as −0.2034 C/m2. The above phenomenon may be related to the different surface atom densities of (100) and (111) silicon surfaces.

Neurochemistry of L-Glutamate Transport in the CNS: A Review of Thirty Years of Progress

2001 ◽  
Vol 66 (9) ◽  
pp. 1315-1340 ◽  
Author(s):  
Vladimir J. Balcar ◽  
Akiko Takamoto ◽  
Yukio Yoneda
Keyword(s):  
Molecular Biology ◽  
Glutamate Transport ◽  
Mammalian Brain ◽  
Activity Data ◽  
System A ◽  
Recent Developments ◽  
The Central Nervous System ◽  
Health And Disease ◽  
Disease Analysis

The review highlights the landmark studies leading from the discovery and initial characterization of the Na+-dependent "high affinity" uptake in the mammalian brain to the cloning of individual transporters and the subsequent expansion of the field into the realm of molecular biology. When the data and hypotheses from 1970's are confronted with the recent developments in the field, we can conclude that the suggestions made nearly thirty years ago were essentially correct: the uptake, mediated by an active transport into neurons and glial cells, serves to control the extracellular concentrations of L-glutamate and prevents the neurotoxicity. The modern techniques of molecular biology may have provided additional data on the nature and location of the transporters but the classical neurochemical approach, using structural analogues of glutamate designed as specific inhibitors or substrates for glutamate transport, has been crucial for the investigations of particular roles that glutamate transport might play in health and disease. Analysis of recent structure/activity data presented in this review has yielded a novel insight into the pharmacological characteristics of L-glutamate transport, suggesting existence of additional heterogeneity in the system, beyond that so far discovered by molecular genetics. More compounds that specifically interact with individual glutamate transporters are urgently needed for more detailed investigations of neurochemical characteristics of glutamatergic transport and its integration into the glutamatergic synapses in the central nervous system. A review with 162 references.

scholarly journals A global non-invasive methodology for the phenotyping of potato under water deficit conditions using imaging, physiological and molecular tools

Plant Methods ◽  
2021 ◽  
Vol 17 (1) ◽  
Author(s):  
M. Musse ◽  
G. Hajjar ◽  
N. Ali ◽  
B. Billiot ◽  
G. Joly ◽  
...  
Keyword(s):  
Water Stress ◽  
Water Deficit ◽  
Soil Conditions ◽  
Growth Stages ◽  
Dry Matter Content ◽  
Tuber Growth ◽  
Non Invasive ◽  
Potato Plants ◽  
Significant Difference

Abstract Background Drought is a major consequence of global heating that has negative impacts on agriculture. Potato is a drought-sensitive crop; tuber growth and dry matter content may both be impacted. Moreover, water deficit can induce physiological disorders such as glassy tubers and internal rust spots. The response of potato plants to drought is complex and can be affected by cultivar type, climatic and soil conditions, and the point at which water stress occurs during growth. The characterization of adaptive responses in plants presents a major phenotyping challenge. There is therefore a demand for the development of non-invasive analytical techniques to improve phenotyping. Results This project aimed to take advantage of innovative approaches in MRI, phenotyping and molecular biology to evaluate the effects of water stress on potato plants during growth. Plants were cultivated in pots under different water conditions. A control group of plants were cultivated under optimal water uptake conditions. Other groups were cultivated under mild and severe water deficiency conditions (40 and 20% of field capacity, respectively) applied at different tuber growth phases (initiation, filling). Water stress was evaluated by monitoring soil water potential. Two fully-equipped imaging cabinets were set up to characterize plant morphology using high definition color cameras (top and side views) and to measure plant stress using RGB cameras. The response of potato plants to water stress depended on the intensity and duration of the stress. Three-dimensional morphological images of the underground organs of potato plants in pots were recorded using a 1.5 T MRI scanner. A significant difference in growth kinetics was observed at the early growth stages between the control and stressed plants. Quantitative PCR analysis was carried out at molecular level on the expression patterns of selected drought-responsive genes. Variations in stress levels were seen to modulate ABA and drought-responsive ABA-dependent and ABA-independent genes. Conclusions This methodology, when applied to the phenotyping of potato under water deficit conditions, provides a quantitative analysis of leaves and tubers properties at microstructural and molecular levels. The approaches thus developed could therefore be effective in the multi-scale characterization of plant response to water stress, from organ development to gene expression.

scholarly journals Current Trends in Non-Invasive Imaging of Interactions in the Liver Tumor Microenvironment Mediated by Tumor Metabolism

Cancers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 3645
Author(s):  
Isabel Theresa Schobert ◽  
Lynn Jeanette Savic
Keyword(s):  
Tumor Microenvironment ◽  
Liver Cancer ◽  
Cancer Cells ◽  
Imaging Techniques ◽  
Treatment Strategies ◽  
Tumor Metabolism ◽  
Resistance Mechanisms ◽  
Metabolic Reprogramming ◽  
Non Invasive

With the increasing understanding of resistance mechanisms mediated by the metabolic reprogramming in cancer cells, there is a growing clinical interest in imaging technologies that allow for the non-invasive characterization of tumor metabolism and the interactions of cancer cells with the tumor microenvironment (TME) mediated through tumor metabolism. Specifically, tumor glycolysis and subsequent tissue acidosis in the realms of the Warburg effect may promote an immunosuppressive TME, causing a substantial barrier to the clinical efficacy of numerous immuno-oncologic treatments. Thus, imaging the varying individual compositions of the TME may provide a more accurate characterization of the individual tumor. This approach can help to identify the most suitable therapy for each individual patient and design new targeted treatment strategies that disable resistance mechanisms in liver cancer. This review article focuses on non-invasive positron-emission tomography (PET)- and MR-based imaging techniques that aim to visualize the crosstalk between tumor cells and their microenvironment in liver cancer mediated by tumor metabolism.

Characterization of synthesized xBaO-(40-x)Li2O-60B2O3 glass system: a multi-dimensional research on optical and physical properties

2021 ◽  
Author(s):  
A. M. A. Mostafa ◽  
E. F. El Agammy ◽  
M. Al-Zaibani ◽  
R. Ramadan ◽  
Shams A. M. Issa ◽  
...  
Keyword(s):  
Physical Properties ◽  
Glass System ◽  
System A
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