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Recent Progress in Polymer Therapeutics as Nanomedicines
Published in Dan Peer, Handbook of Harnessing Biomaterials in Nanomedicine, 2021
Sahar Israeli Dangoor, Shani Koshrovski Michael, Hemda Baabur-Cohen, Liora Omer, Ronit Satchi-Fainaro
PEG has good water solubility, but it can also dissolve in many organic solvents. This feature together with its biocompatibility has made it a versatile carrier in polymer therapeutics. PEG is commercially available with either one or two attachment points. It can be produced as a linear or branched polymer. The functional hydroxyl group at the chain termini can be conjugated to drugs or other functional groups [36]. The lack of multivalency is one of the limitations of this polymer; it limits the loading capacity and the potential use of PEG as a backbone. To overcome this limitation, additional reactive groups can be added by reaction of the OH-groups with multifunctional compounds, such as glutamic acid dendron or dendritic polyglycerol [37, 38]. In addition, branched PEG can also overcome this limitation. In fact, Onzeald (NKTR-102), a 4-arm PEG polymer conjugated to etirinotecan at each of the four chains, through a cleavable linker [39], is under a phase 3 clinical trial for the treatment of patients with metastatic breast cancer who have stable brain metastases. While PEG is mostly common in the field of polymer–protein conjugates, it is also extensively used in the polymer therapeutics field in general, as a drug carrier or as a stabilizing and anti-immunogenic moiety.
Processing Principles
Published in Arthur J. Kidnay, William R. Parrish, Daniel G. McCartney, Fundamentals of Natural Gas Processing, 2019
Arthur J. Kidnay, William R. Parrish, Daniel G. McCartney
The common oxygen compounds naturally occurring in natural gas are carbon dioxide and water. Replacing a hydrogen atom on the water molecule with an alkyl group generates an alcohol, giving the structure R–OH. The OH group is called a hydroxyl group. An important alcohol is methanol, CH3OH. While not found naturally in natural gas, alcohols are important in the natural gas industry. Chapters 8 and 11 cover applications using alcohols.
Applications of Equilibrium Thermodynamics
Published in Kalliat T. Valsaraj, Elizabeth M. Melvin, Principles of Environmental Thermodynamics and Kinetics, 2018
Kalliat T. Valsaraj, Elizabeth M. Melvin
Figure 3.9 represents a mineral surface (silica) where an electron-deficient silicon atom and groups of electron-rich oxygen atoms are presented to the aqueous phase. The surface hydroxyl groups are similar to water molecules in that both can form hydrogen bonds. The adsorption energy for water on a silica surface is −500 mJ m−2. The energy decreases as the surface water molecules are progressively replaced. Water is therefore more favored by most mineral surfaces. There are two possible orientations of water molecules on a mineral surface, as depicted in Figure 3.9. An interesting consequence of these orientations is that water molecules in direct contact with the metal oxide can adopt specific favorable conformations and can simultaneously participate in the tetrahedral three-dimensional network that gives it the special features noted earlier.
The Characterization of Flotation Selectivity of Different Size Coal Fractions
Published in International Journal of Coal Preparation and Utilization, 2018
Yingwei Wang, Yaowen Xing, Xiahui Gui, Yijun Cao, Xuehong Xu
where (-OH) is the absorbance of -OH, (C=O) is the absorbance of C=O, (Si-O-Al) is the absorbance of Si-O-Al, (Ar-H) is the absorbance of Ar-H, (-CH(vas)) is the absorbance of C-H with an asymmetrically stretching vibration, (-CH(vs)) is the absorbance of C-H with a symmetrically stretching vibration, (C=C) is the absorbance of C=C, and (-CH(vb)) is the absorbance of C-H with a bending vibration. The hydroxyl group has dual functionality, having the ability to act as both a hydrogen donor and hydrogen acceptor, whereas the C=O bond acts only as a hydrogen acceptor. Therefore, the contribution to the hydrophilic characteristics of the hydroxyl group is expected to be twice that of the C=O bonds, so a factor of 2 is used for the absorption intensity coefficient for the hydroxyl group, whereas the coefficients for other functional groups at this time are assumed to be unity [35]. The absorbance of the related functional groups was obtained from Figures 7–9, and the HI values calculated using Equation 8 are shown in Table 8.
A Study on the Spontaneous Combustion Oxidation Properties of Unloaded Coal at Various Surrounding Rock Temperatures
Published in Combustion Science and Technology, 2021
Rongkun Pan, Wentao Tang, Shuaidong Wu, Junwei Ma, Dong Fu, Hailin Jia
Hydroxyl groups comprise an important type of functional group in coal molecules that affects the oxidation properties of the coal. Hydroxyl groups contain three types of hydrogen (H) bonds, namely, free, intermolecular self-associated and intramolecular H bonds. The higher is the hydroxyl group content of a molecular structure, the easier it can combine and react with O2. The absorption peak region between 3,700 and 3,200 cm−1 was the absorption and vibration region of the hydroxyl groups. Table 2 summarizes the hydroxyl peak areas determined by the fitting results. Figure 5 shows the changes in the hydroxyl peak area of each coal sample.