scholarly journals Comparison between modified LST Fastfloat and conventional HF methods for pollen preparation in highly minerogenic sediments

2021 ◽  
Vol 93 (1) ◽  
pp. 5-18
Author(s):  
Tiina Eskola ◽  
◽  
Riitta Kontio ◽  
Juha Pekka Lunkka ◽  
◽  
...  
Keyword(s):  
Confidence Interval ◽  
Pollen Analysis ◽  
Hydrofluoric Acid ◽  
Preparation Method ◽  
Toxic Chemicals ◽  
Heavy Liquid ◽  
Liquid Lithium ◽  
Preparation Technique ◽  
Paired Samples ◽  
Sample Pair

Pollen analysis is a commonly used method to interpret vegetation and environmental change. The standard pollen preparation technique in minerogenic sediments involves the use of hydrofluoric acid (HF) which is highly toxic. Currently the European legislation requires that hazardous chemicals should be substituted with less hazardous or non-toxic chemicals if possible. In the present paper the authors introduce a safer pollen preparation method, based on the use of low-toxic heavy liquid lithium heteropoly-tungstate (LST Fastfloat) and provide instructions for pollen preparation with the LSTFastflow method. Furthermore, five paired samples were processed from clayey and silty sediments with LST Fastfloat and conventional HF methods and the pollen and spore counting results obtained from these two methods were compared to test if there is statistically significant differences between the taxa. Calculation of the 95% confidence interval revealed statistical agreement in all studied taxa except one taxon in one sample pair. However, the study revealed systematic differences within two taxa, Betula and Pinus. Thus caution is needed when comparing results obtained by HF and heavy liquid (LST Fastfloat) methods.

Rapid, Non-Toxic Synthesis of Beta Zeolites

2018 ◽  
Author(s):  
Felix Hemmann ◽  
Jonathan Hackebeil ◽  
Andreas Lißner ◽  
Florian Mertens
Keyword(s):  
Hydrofluoric Acid ◽  
Molecular Sieves ◽  
Toxic Chemicals ◽  
Lewis Acidity ◽  
Beta Zeolite ◽  
Seeded Growth ◽  
Related Research ◽  
Beta Zeolites ◽  
Growth Method ◽  
Fast Synthesis

Molecular sieves with beta zeolite topology are promising catalysts for various reactions as they exhibits extraordinary Lewis acidity. However, their industrial application and related research in academica is hindered because their synthesis is time consuming and typically involves toxic chemicals as hydrofluoric acid. Therefore, tetraethylammonium fluorid was tested as a non-toxic fluotide source for the synthesis of beta zeolites. In combination with the previously reported nano-seeded growth method, a fast synthesis of beta zeolites only involving non-toxic chemicals was possible. Synthesized zeolites show comparable selectivity in the Bayer-Villinger oxidation as conventional zeolites synthesized with hydrofluoric acid.<br>

scholarly journals Silane Heat Treatment Could Eliminate the Hydrofluoric Acid Etching of Lithium Disilicate Overlays: A Four-Year Follow-Up

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Spartak Spasov Yanakiev ◽  
Mirela Borislavova Marinova-Takorova
Keyword(s):  
Heat Treatment ◽  
Bond Strength ◽  
Hydrofluoric Acid ◽  
Lithium Disilicate ◽  
Acid Etching ◽  
Preparation Technique ◽  
Ceramic Surface ◽  
Dental Adhesive ◽  
Ceramic Bond

A four-year follow-up of a novel silane heat treatment method for bonding lithium disilicate overlays to tooth structures without hydrofluoric acid etching of the ceramic surface is presented in this case report. Silane heat treatment modifies the silane layer and thus enhances resin ceramic bond strength without hydrofluoric acid etching. The standard ceramic preparation technique prior to bonding silicate ceramics to tooth structure is hydrofluoric acid etching and applying a silane coupling agent, followed by dental adhesive. In this case, the micromechanical roughening of the ceramic surface was performed by air abrasion with Al2O3. Silane heat treatment with constant 120°C airflow, applied for 60 sec, followed by dental adhesive application enhanced the resin-ceramic bond strength. After a four-year follow-up, the restorations’ clinical appearance could be defined as excellent/very good according to the FDI clinical criteria for the evaluation of direct and indirect restorations. This clinical result supports many in vitro studies regarding the resin-ceramic bond strength and durability obtained through postsilanization heat treatment.

scholarly journals Optimizing Acetabular Component Bone Ingrowth: The Wedge-Fit Bone Preparation Method

2019 ◽  
Vol 2019 ◽  
pp. 1-6
Author(s):  
Dani M. Gaillard-Campbell ◽  
Thomas P. Gross
Keyword(s):  
Acetabular Component ◽  
Preparation Method ◽  
Bone Ingrowth ◽  
Hip Resurfacing ◽  
Outer Diameter ◽  
Preparation Technique ◽  
Acetabular Bone ◽  
Press Fit ◽  
Unexplained Pain ◽  
Clinical Problems

We investigate the efficacy of a modified acetabular bone-preparation technique in reducing the incidence of two clinical problems identified in hip resurfacing arthroplasty. The first issue is failure due to lack of bone ingrowth into the acetabular component. The second is a newly recognized phenomenon of early cup shift. We hypothesize that these issues might be resolved by using a “wedge-fit method”, in which the component wedges into the peripheral acetabular bone rather than bottoming out and potentially toggling on the apex of the cup. Prior to November 2011, all acetabula were reamed 1 mm under and prepared with a press-fit of the porous coated acetabular component. After November 2011, we adjusted reaming by bone density. In “soft bone” (T-score <-1.0), we underreamed acetabula by 1 mm less than the outer diameter of the cup, as was previously done in all cases. For T-scores greater than -1.0, we reamed line-to-line. Additionally, we began performing an “apex relief” starting June 2012 in all cases by removing 2 mm of apex bone with a small reamer after using the largest reamer. Failure of acetabular ingrowth occurred in 0.5% of cases before the wedge-fit method and <0.1% after. Rate of cup shift was reduced from 1.1% to 0.4%. The rate of unexplained pain between 2 and 4 years postoperatively also declined significantly from 2.6% to 1.3%. Our evidence suggests that wedge-fit acetabular preparation improves initial implant stability, leading to fewer cases of early cup shift, unexplained pain, and acetabular ingrowth failure.

Embedding of unfixed plant material in water-soluble resin: A simple preparation method for elemental analysis by ESI and EELS techniques

1990 ◽  
Vol 48 (3) ◽  
pp. 772-773
Author(s):  
Heiner Lehmann ◽  
Ulrike Kunz
Keyword(s):  
Preparation Method ◽  
Plant Cells ◽  
Inorganic Ions ◽  
Living Cells ◽  
Water Soluble ◽  
Preparation Technique ◽  
Chemical Fixation ◽  
Electron Spectroscopic Imaging ◽  
Simple Preparation ◽  
Electron Energy Loss

The localization of elements in cells and tissues by electron spectroscopic imaging (ESI) or electron energy loss spectroscopy (EELS) can be realized only in very thin specimens in order to avoid multiple scattering of the electrons. Therefore the biological material has to be cut in thin 30 nm sections.The commonly used preparation procedure is a hydrous chemical fixation followed by dehydration, embedding in hydrophobic resin and ultrathin sectioning. The disadvantage of this procedure is the loss and/or dislocation of inorganic ions and other water-soluble substances. To overcome these difficulties the preferable preparation method is cryofixation in combination with cryosubstitution, but this is a very expensive and time-wasting procedure.Meanwhile, we established a more simplified preparation technique, which shows reasonable results on plant cells without large central vacuoles: The living cells were directly put into freshly mixed Nanoplast FB 101, a water-soluble melanine resin, and stored for 24 h at 20° C in a silca gel containing exsiccator.

Alternative Sample Preparation Technique for Die Level Parallel Lapping Analysis

2013 ◽  
Author(s):  
Hoon Ye Gwee ◽  
Kiong Kay Ng
Keyword(s):  
Integrated Circuits ◽  
Sample Preparation ◽  
Preparation Method ◽  
Preparation Technique ◽  
Sample Preparation Method ◽  
Simple Method ◽  
Sample Preparation Technique ◽  
Sem Imaging ◽  
Voltage Contrast ◽  
Super Glue

Abstract Parallel lapping (often called delayering) is a commonly used process in failure analysis of integrated circuits. However, parallel lapping commonly gives rise to the issue of weak sample preparation method especially on specimen mounting. The traditional specimen mounting technique was done by mounted a single die to polishing fixture using drop of super glue. Using conventional methods, problems such as losing the die during polishing, serious edge rounding are often encountered. Further, loading the whole polishing fixture into Scanning Electron Microscopy machine for SEM imaging or Passive Voltage Contrast (PVC) fault localization can be complicated due to the size of polishing fixture. Therefore, an alternative, relatively fast and simple method to overcome the above mentioned obstacles is proposed.

Appendix. Palynology of the Quaternary sediments in borehole V 050

1975 ◽  
Vol 279 (1288) ◽  
pp. 253-256
Keyword(s):  
Pollen Analysis ◽  
Inorganic Material ◽  
Heavy Liquid ◽  
Quaternary Sediments ◽  
Tree Pollen ◽  
Spores And Pollen ◽  
Standard Methods ◽  
Pollen And Spores ◽  
Total Tree

Samples taken at representative levels from the cores of borehole V 050 have been treated for pollen analysis. Standard methods of removing organic and inorganic material have been employed, followed by concentration of the spores and pollen using a heavy liquid (bromo-form-ethanol,D 2.1). The pollen and spores were determined at each level, the results being shown in the accompanying diagram as percentages of total tree pollen, rather than as absolute percentages.

Statistical Inference for a Ratio of Dispersions Using Paired Samples

2003 ◽  
Vol 28 (1) ◽  
pp. 21-30 ◽  
Author(s):  
Douglas G. Bonett ◽  
Edith Seier
Keyword(s):  
Confidence Interval ◽  
Error Rates ◽  
Small Sample ◽  
Type I ◽  
Type Ii Error ◽  
Paired Data ◽  
Nonnormal Distributions ◽  
Paired Samples ◽  
Robust Tests ◽  
Small Sample Sizes

Wilcox (1990) examined the Type I and Type II error rates for several robust tests of H0: σ12/σ22 = 1 in paired-data designs and concluded that a satisfactory solution does not yet exist. A confidence interval for a ratio of correlated mean absolute deviations is derived and performs well in small sample sizes across realistically nonnormal distributions. When used to test a hypothesis, the proposed confidence interval is almost as powerful as the most powerful test examined by Wilcox.

scholarly journals Matrix solid phase dispersion as an effective preparation method for food samples and plants before HPLC analysis – a riview

2011 ◽  
Vol 21 (No. 6) ◽  
pp. 219-234 ◽  
Author(s):  
G. Karasová ◽  
E. Branšteterová ◽  
M. Lachová
Keyword(s):  
Hplc Analysis ◽  
Preparation Method ◽  
Solid Phase ◽  
Food Samples ◽  
Preparation Technique ◽  
Main Principle ◽  
Advantages And Disadvantages ◽  
Matrix Solid Phase Dispersion ◽  
Phase Dispersion ◽  
Factors Influencing

This review deals with a preparation technique &ndash; Matrix Solid Phase Dispersion (MSPD) and its possibilities in the HPLC analysis for contaminants, pesticides, drug residues, and natural compounds in food samples. The main principle of MSPD is explained, the important factors influencing the effectivity and recovery of this technique are discussed. The advantages and disadvantages of MSPD and other classical extraction, isolation, and purifica&shy;tion procedures are compared. The present article provides a bibliography of MSPD applications in food sample matrices during last years for various analytes and different sample matrices. &nbsp;

scholarly journals Tratamento de Superfície em Cerâmicas de Dissilicato de Lítio: uma Revisão de Literatura

2020 ◽  
Vol 24 (4) ◽  
pp. 422-425
Author(s):  
Gabriela Torres Zanin ◽  
Omar Geha ◽  
Ricardo Danil Guiraldo ◽  
Murilo Baena Lopes ◽  
Sandrine Bittencourt Berger
Keyword(s):  
Latin American ◽  
Hydrofluoric Acid ◽  
Preparation Method ◽  
Surface Preparation ◽  
Lithium Disilicate ◽  
Caribbean Literature ◽  
Electronic Library ◽  
Ceramic Surfaces ◽  
Final Sample ◽  
Wide Range

O preparo das superfícies cerâmicas é umas das etapas fundamentais para uma adesão duradoura e satisfatória no substrato dentário, garantindo o sucesso do tratamento. A escolha dos produtos corretos confere à prótese maior estabilidade após cimentação, evitando: infiltrações, cáries secundárias e deslocamento da peça cerâmica. Nos últimos tempos, vários protocolos para preparo das superfícies cerâmicas estão sendo usados em função da ampla oferta de produtos no mercado. Diante da diversidade de produtos disponíveis, esta revisão de literatura tem como objetivo mostrar, por meio de artigos, qual o protocolo mais seguro a ser seguido para a cimentação de cerâmicas de dissilicato de lítio. Realizou-se uma revisão de literatura baseada em artigos científicos publicados nas seguintes bases de dados: Scientific Electronic Library Online (SciELO), Medline: Pubmed e Literatura Latino-Americana e do Caribe em Ciências da Saúde (Lilacs), sendo a amostra final composta por vinte e seis estudos. Verificou-se que, para uma adesão adequada das cerâmicas de dissilicato de lítio ao substrato dentário, deve-se seguir o passo a passo do preparo da superfície, sendo a aplicação do ácido fluorídrico, seguido de silano e adesivo a opção mais segura. O modo simplificado de preparo, usando sistemas autocondicionantes pode ser promissor, porém mais estudos são necessários para comprovar sua eficácia.   Palavras-chave: Ácido Fluorídrico. Adesivos. Dissilicato de Lítio.   Abstract The  ceramic surfaces preparation is one of the fundamental steps for a lasting and satisfactory adhesion to the dental substrate, guaranteeing the success of the treatment. The  correct products choice gives the prosthesis greater stability after cementation, avoiding: infiltrations, secondary caries and e ceramic piece displacement. In recent times, several protocols for preparing ceramic surfaces have been used due to the wide range of products in  the market. Due to the diversity of products available, this literature review aims to show, through articles, which is the safest protocol to be followed for the cementation of lithium disilicate ceramics. A review was carried out based on scientific articles published in the databases: Scientific Electronic Library Online (SciELO), Medline: Pubmed and Latin American and Caribbean Literature in Health Sciences (Lilacs), with the final sample comprising twenty-six studies. It was found that, for an adequate lithium disilicate ceramics adhesion to the dental substrate, one must follow the step by  step of the surface preparation, with the hydrofluoric acid (HF) application, followed by silane and adhesive which is the safest option. The simplified  preparation method, using self-etching systems, can be promising, however, more studies are needed to prove its effectiveness.   Keywords: Hydrofluoric Acid. Adhesives. Lithium Disilicate.

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