Development of an Environmentally Friendly Resist-Removal Process Using Wet Ozone

We investigated the removal of polymers with various chemical structures and the removal of ion-implanted resists using wet ozone. The removal rates of polymers that have carbon-carbon (C–C) double bonds in the main chain were high. The main chain of these polymers may be decomposed. The removal rates of polymers that have C–C double bonds in the side chain were low. The benzene ring in the side chain changes into carboxylic acid, so their ability to dissolve in water increased. The polymers without C–C double bonds were not removed. Removal of B and P ion-implanted resists became difficult with increasing acceleration energy of ions at implantation. The resist with plastic-deformation hardness that was twice as hard as that of nonimplanted resist should be removed similarly to nonimplanted resist. Using TOF-SIMS, we clarified that the molecule of cresol novolak resin was destroyed and carbonized by ion implantation.

Download Full-text

Influence of cyclodextrin on the solubility of a classically prepared 2-vinylcyclopropane macromonomer in aqueous solution

Beilstein Journal of Organic Chemistry ◽

10.3762/bjoc.8.173 ◽

2012 ◽

Vol 8 ◽

pp. 1528-1535 ◽

Cited By ~ 8

Author(s):

Helmut Ritter ◽

Jia Cheng ◽

Monir Tabatabai

Keyword(s):

Aqueous Solution ◽

Carboxylic Acid ◽

Graft Copolymer ◽

Ring Opening ◽

Main Chain ◽

Double Bonds ◽

Radical Ring ◽

Unsaturated Polymer ◽

End Group ◽

Clouding Point

A macromonomer 5 consisting of a polymerizable vinylcyclopropane end group and a poly(N-isopropylacrylamide) (poly(NiPAAm)) chain was obtained from amidation of 1-ethoxycarbonyl-2-vinylcyclopropane-1-carboxylic acid (4) with an amino-terminated poly(NiPAAm) 3 as an example. This macromonomer 5 showed an LCST effect after complexation of the vinyl end group with ß-cyclodextrin in water. Via radical ring-opening copolymerization of 5 and NiPAAm a graft copolymer 8 with a clouding point of 32 °C was synthesized. The branched unsaturated polymer was treated with ozone to cleave the double bonds of the main chain.

Download Full-text

Electron Diffraction Analysis of Microtwin Structures in Regrown (III) Silicon

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100054765 ◽

1982 ◽

Vol 40 ◽

pp. 460-461

Author(s):

P. Ling ◽

R. Gronsky ◽

J. Washburn

Keyword(s):

Electron Diffraction ◽

Ion Implantation ◽

Diffraction Analysis ◽

Diffraction Pattern ◽

Direct Consequence ◽

The Other ◽

Electron Diffraction Analysis ◽

Defect Microstructures ◽

Ion Implanted

The defect microstructures of Si arising from ion implantation and subsequent regrowth for a (111) substrate have been found to be dominated by microtwins. Figure 1(a) is a typical diffraction pattern of annealed ion-implanted (111) Si showing two groups of extra diffraction spots; one at positions (m, n integers), the other at adjacent positions between <000> and <220>. The object of the present paper is to show that these extra reflections are a direct consequence of the microtwins in the material.

Download Full-text

Faculty Opinions recommendation of Main chain and side chain dynamics of oxidized flavodoxin from Cyanobacterium anabaena.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1002693.29208 ◽

2001 ◽

Author(s):

Vincent Rotello

Keyword(s):

Main Chain ◽

Side Chain ◽

Chain Dynamics ◽

Cyanobacterium Anabaena ◽

Side Chain Dynamics

Download Full-text

Effect of Nitrogen Ion Implantation on the Cavitation Erosion Resistance and Cobalt-Based Solid Solution Phase Transformations of HIPed Stellite 6

Materials ◽

10.3390/ma14092324 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2324

Author(s):

Mirosław Szala ◽

Dariusz Chocyk ◽

Anna Skic ◽

Mariusz Kamiński ◽

Wojciech Macek ◽

...

Keyword(s):

Plastic Deformation ◽

Stainless Steel ◽

Ion Implantation ◽

Phase Transformations ◽

Erosion Rate ◽

Cavitation Erosion ◽

Matrix Phase ◽

Nitrogen Ion Implantation ◽

Stellite 6 ◽

Nitrogen Ion

From the wide range of engineering materials traditional Stellite 6 (cobalt alloy) exhibits excellent resistance to cavitation erosion (CE). Nonetheless, the influence of ion implantation of cobalt alloys on the CE behaviour has not been completely clarified by the literature. Thus, this work investigates the effect of nitrogen ion implantation (NII) of HIPed Stellite 6 on the improvement of resistance to CE. Finally, the cobalt-rich matrix phase transformations due to both NII and cavitation load were studied. The CE resistance of stellites ion-implanted by 120 keV N+ ions two fluences: 5 × 1016 cm−2 and 1 × 1017 cm−2 were comparatively analysed with the unimplanted stellite and AISI 304 stainless steel. CE tests were conducted according to ASTM G32 with stationary specimen method. Erosion rate curves and mean depth of erosion confirm that the nitrogen-implanted HIPed Stellite 6 two times exceeds the resistance to CE than unimplanted stellite, and has almost ten times higher CE reference than stainless steel. The X-ray diffraction (XRD) confirms that NII of HIPed Stellite 6 favours transformation of the ε(hcp) to γ(fcc) structure. Unimplanted stellite ε-rich matrix is less prone to plastic deformation than γ and consequently, increase of γ phase effectively holds carbides in cobalt matrix and prevents Cr7C3 debonding. This phenomenon elongates three times the CE incubation stage, slows erosion rate and mitigates the material loss. Metastable γ structure formed by ion implantation consumes the cavitation load for work-hardening and γ → ε martensitic transformation. In further CE stages, phases transform as for unimplanted alloy namely, the cavitation-inducted recovery process, removal of strain, dislocations resulting in increase of γ phase. The CE mechanism was investigated using a surface profilometer, atomic force microscopy, SEM-EDS and XRD. HIPed Stellite 6 wear behaviour relies on the plastic deformation of cobalt matrix, starting at Cr7C3/matrix interfaces. Once the Cr7C3 particles lose from the matrix restrain, they debond from matrix and are removed from the material. Carbides detachment creates cavitation pits which initiate cracks propagation through cobalt matrix, that leads to loss of matrix phase and as a result the CE proceeds with a detachment of massive chunk of materials.

Download Full-text

Formation of Amphiphilic Molecules from the Most Common Marine Polysaccharides, toward a Sustainable Alternative?

Molecules ◽

10.3390/molecules26154445 ◽

2021 ◽

Vol 26 (15) ◽

pp. 4445

Author(s):

Tiphaine Wong ◽

Lorette Brault ◽

Eric Gasparotto ◽

Romuald Vallée ◽

Pierre-Yves Morvan ◽

...

Keyword(s):

Fatty Acid ◽

Carboxylic Acid ◽

Bioactive Compounds ◽

Biological Properties ◽

Cross Linking ◽

Structural Modifications ◽

Chemical Structures ◽

Amphiphilic Molecules

Marine polysaccharides are part of the huge seaweeds resources and present many applications for several industries. In order to widen their potential as additives or bioactive compounds, some structural modifications have been studied. Among them, simple hydrophobization reactions have been developed in order to yield to grafted polysaccharides bearing acyl-, aryl-, alkyl-, and alkenyl-groups or fatty acid chains. The resulting polymers are able to present modified physicochemical and/or biological properties of interest in the current pharmaceutical, cosmetics, or food fields. This review covers the chemical structures of the main marine polysaccharides, and then focuses on their structural modifications, and especially on hydrophobization reactions mainly esterification, acylation, alkylation, amidation, or even cross-linking reaction on native hydroxyl-, amine, or carboxylic acid functions. Finally, the question of the necessary requirement for more sustainable processes around these structural modulations of marine polysaccharides is addressed, considering the development of greener technologies applied to traditional polysaccharides.

Download Full-text

Responsive Polyesters with Alkene and Carboxylic Acid Side-Groups for Tissue Engineering Applications

Polymers ◽

10.3390/polym13101636 ◽

2021 ◽

Vol 13 (10) ◽

pp. 1636

Author(s):

Stella Afroditi Mountaki ◽

Maria Kaliva ◽

Konstantinos Loukelis ◽

Maria Chatzinikolaidou ◽

Maria Vamvakaki

Keyword(s):

Carboxylic Acid ◽

Chain Length ◽

Main Chain ◽

Alkyl Chain ◽

Click Reaction ◽

Irradiation Time ◽

Alkyl Chain Length ◽

Polymer Chains ◽

Condensation Polymerization ◽

L929 Fibroblast

Main chain polyesters have been extensively used in the biomedical field. Despite their many advantages, including biocompatibility, biodegradability, and others, these materials are rather inert and lack specific functionalities which will endow them with additional biological and responsive properties. In this work, novel pH-responsive main chain polyesters have been prepared by a conventional condensation polymerization of a vinyl functionalized diol with a diacid chloride, followed by a photo-induced thiol-ene click reaction to attach functional carboxylic acid side-groups along the polymer chains. Two different mercaptocarboxylic acids were employed, allowing to vary the alkyl chain length of the polymer pendant groups. Moreover, the degree of modification, and as a result, the carboxylic acid content of the polymers, was easily tuned by varying the irradiation time during the click reaction. Both these parameters, were shown to strongly influence the responsive behavior of the polyesters, which presented adjustable pKα values and water solubilities. Finally, the difunctional polyesters bearing the alkene and carboxylic acid functionalities enabled the preparation of cross-linked polyester films by chemically linking the pendant vinyl bonds on the polymer side groups. The biocompatibility of the cross-linked polymers films was assessed in L929 fibroblast cultures and showed that the cell viability, proliferation, and attachment were greatly promoted on the polyester surface, bearing the shorter alkyl chain length side groups and the higher fraction of carboxylic acid functionalities.

Download Full-text

Substrate Scope for Human Histone Lysine Acetyltransferase KAT8

International Journal of Molecular Sciences ◽

10.3390/ijms22020846 ◽

2021 ◽

Vol 22 (2) ◽

pp. 846

Author(s):

Giordano Proietti ◽

Yali Wang ◽

Chiara Punzo ◽

Jasmin Mecinović

Keyword(s):

Main Chain ◽

Coenzyme A ◽

Side Chain ◽

Histone H4 ◽

Chemical Probes ◽

Acetyl Coenzyme A ◽

Acetyl Coenzyme ◽

Histone Lysine ◽

Lysine Acetyltransferase

Biomedically important histone lysine acetyltransferase KAT8 catalyses the acetyl coenzyme A-dependent acetylation of lysine on histone and other proteins. Here, we explore the ability of human KAT8 to catalyse the acetylation of histone H4 peptides possessing lysine and its analogues at position 16 (H4K16). Our synthetic and enzymatic studies on chemically and structurally diverse lysine mimics demonstrate that KAT8 also has a capacity to acetylate selected lysine analogues that possess subtle changes on the side chain and main chain. Overall, this work highlights that KAT8 has a broader substrate scope beyond natural lysine, and contributes to the design of new chemical probes targeting KAT8 and other members of the histone lysine acetyltransferase (KAT) family.

Download Full-text