Polymer Science: From Basics to Nanotechnology Applications

This work explores the complicated realm of fullerene structures by utilizing an innovative algebraic lens to unravel their chemical intricacies. We reveal a more profound comprehension of the structural subtleties of fullerenes by the computation of modified polynomials that are customized to their distinct geometric and electrical characteristics. In addition to enhancing the theoretical underpinnings, the interaction between algebraic characteristics and fullerene structures creates opportunities for real‐world applications in materials science and nanotechnology. Our results provide a novel viewpoint that bridges the gap between algebraic abstraction and chemical reality. They also open up new avenues for the manipulation and construction of materials based on fullerenes with customized features. Topological or numerical descriptors are used to associate important physicomolecular restrictions with important molecular structural features such as periodicity, melting and boiling points, and heat content for various 2 and 3D molecular preparation graphs or networking. The degree of an atom in a molecular network or molecular structure is utilized in this study to calculate the degree of atom‐based numerics. The modified polynomial technique is a more recent way of assessing molecular systems and geometries in chemoinformatics. It emphasizes the polynomial nature of molecular features and gives numerics in algebraic expression. Particularly in this context, we describe multiple cages topologically based on the fullerene molecular form as polynomials, and several algebraic properties, including the Randić number and the modified polynomials of the first and second Zagreb numbers, are measured. By applying algebraic methods, we computed topological descriptors such as the Randić number and Zagreb indices. Our qualitative analysis shows that these descriptors significantly improve the prediction of molecular behavior. For instance, the Randić index provided insights into the stability and reactivity of fullerene structures, while the Zagreb indices helped us understand their potential in electronic applications. Our results suggest that modified polynomials not only offer a refined perspective on fullerene structures but also enable the design of materials with tailored properties. This study highlights the potential for these algebraic tools to bridge the gap between theoretical models and practical applications in nanotechnology and materials science, paving the way for innovations in drug delivery, electronic devices, and catalysis.

Concentration Insensitive Supramolecular Polymerization Enabled by Kinetically Interlocking Multiple-Units Strategy

These proceedings are based on the program of the workshop dedicated to New Energy System and Electrical Engineering. Understanding the path from New Energy Systems to Electrical and Power Engineering will involve a strong interdisciplinary interaction among experts in theory and applications. In this workshop a particular attention was devoted to applications in New Energy System and Electrical Engineering.2022 4th International Conference on New Energy System and Electrical Engineering (NESEE 2022) took place virtually in Chongqing, China from December 9th to 11th, 2022. It can be expected that with the recent developments in the fields towards more user-friendly new energy system and electrical engineering, new energy and electrical will become a vital link in the chain of sustainable development and highly automation in the near future.Many scientists and researchers all over the world have contributed to the emerging technology of new energy and electrical engineering. At this meeting we had a comprehensive overview of these fascinating fields and of future scenarios thanks to the participation of leaders of the most important projects. Fushuan Wen, a renowned professor from Zhejiang University, China, made a keynote speech and shared his research Restoring a Faulted Power System Having Rich Renewable Energy Generation in Electricity Market Environment with us. His research domains include: a) power economics and electricity markets; b) power system investment, planning and operation optimization; c) smart grids and electric vehicles; d) power system alarm processing, fault diagnosis and system restoration; e) artificial intelligence.The plenary sessions covered a broad range of topics, as we considered it important to promote communication between the communities pursuing research in different areas of new energy and electrical engineering. The topics discussed included Energy Saving Technologies, Energy Storage Technologies, Thermal and Power Engineering, Electrical Automation and Power Engineering, Smart Grid / Power IC, Power Machinery and Engineering, etc.The NESEE conferences in the past have proven to be an important forum at which energy scientists, chemists, electrical specialists brought together a critical mass of thoughts, findings and considerations and have been endorsed by many international and national energy and electrical organizations and publishers.We hope that this NESEE 2022 conference has been a useful contribution to the fields of new energy and electrical engineering, and that it may encourage the organization of subsequent NESEE conferences on these diverse, challenging and fascinating fields.Last but not the least is our acknowledgement. We would like to thank all the participants, especially those who contributed speeches, posters and manuscripts, for making NESEE 2022 such an exciting and memorable conference. We thank the Technical Program Committee members, for putting together an outstanding program. We gratefully acknowledge the support of editors and members of the Journal of Physics: Conference Series, for their efforts in making this volume published.The Committee of NESEE 2022List of Committee Member is available in this Pdf.

Hybrid energy plants, which include both fossil fuel technologies and renewable energy systems, can provide an important step towards a sustainable energy supply. In fact, the hybridization of renewable energy systems with gas turbines which are fed by fossil fuels allows an acceptable compromise, so that high fossil fuel efficiency and high share of renewables can be potentially achieved. Moreover, electrical and thermal energy storage systems increase the flexibility of the energy plant and effectively manage the variability of energy production and demand. This paper investigates the optimal sizing of a hybrid energy plant which combines an industrial gas turbine, renewable energy systems and energy storage technologies. The considered renewable energy system is a photovoltaic system, while the energy storage technologies are electrical energy storage and thermal energy storage. Moreover, a compression chiller and a gas boiler are also considered. For this purpose, the load profiles of electricity, heating and cooling during a whole year are taken into account for the case study of the Campus of the University of Parma (Italy). The sizing optimization problem of the different technologies composing the hybrid energy plant is solved by using a genetic algorithm, with the goal of minimizing primary energy consumption. Moreover, different operation strategies are analyzed and compared so that plant operation is also optimized. The results demonstrate that the optimal sizing of the hybrid energy plant, coupled with the optimized operation strategy, allows high average cogeneration efficiency (up to 84%), thus minimizing primary energy consumption.

Journal of Biomedical Materials ResearchVolume 28, Issue 1 p. 137-137 ErratumFree Access Functional versus quantitative comparison of IL-1β from monocytes/macrophages on biomedical polymers Dr T. L. Bonfield, Dr T. L. Bonfield Departments of Pathology, Macromolecular Science, and Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106-4907Search for more papers by this authorDr. J. M. Anderson, Corresponding Author Dr. J. M. Anderson Departments of Pathology, Macromolecular Science, and Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106-4907Departments of Pathology, Macromolecular Science, and Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106-4907Search for more papers by this author Dr T. L. Bonfield, Dr T. L. Bonfield Departments of Pathology, Macromolecular Science, and Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106-4907Search for more papers by this authorDr. J. M. Anderson, Corresponding Author Dr. J. M. Anderson Departments of Pathology, Macromolecular Science, and Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106-4907Departments of Pathology, Macromolecular Science, and Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106-4907Search for more papers by this author First published: January 1994 https://doi.org/10.1002/jbm.820280118AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. Volume28, Issue1January 1994Pages 137-137 RelatedInformation

Combinatorial Evaluation of Cations, pH-sensitive and Hydrophobic Moieties for Polymeric Vector Design

Analysis of tissue and arterial blood temperatures in the resting human forearm. 1948.

MOL2NET-07, Conference on Molecular, Biomedical, and Computational Sciences and Engineering, ISSN: 2624-5078, MDPI SciForum, Basel, Switzerland, 2021, 7th ed.

In the Spring of 2005, the Oregon Institute of Technology began offering its new Bachelors of Science degree program in renewable energy systems. This degree program incorporates the fundamentals of electrical and mechanical engineering, with an aim towards preparing students for careers in the power and renewable energy industries. We intend to develop this program into a fully-accredited engineering program, one that establishes momentum towards revitalizing undergraduate education in power and energy systems engineering. Furthermore, this program has been successful in attracting students who are not traditionally interested in engineering. The appeal of the renewable energy engineering curriculum offers the potential to expand the pool of engineering students by attracting students who would not otherwise apply to traditional engineering schools. This paper also provides suggestions for other schools interested in initiating a similar degree program

Sustainability and resilience are major challenges for the building sector in order to meet energy efficiency and low carbon emissions goals. Based on the defined and quantified targets of the EU climate change policy, Renewable Energy Systems (RESs) are among the top-priority measures for accomplishing the target of decarbonization in buildings. Nevertheless, the choice of the type of RES is not a one-dimensional problem, and the optimal combination may not be unique. The aim of this paper is the energy and environmental evaluation of renewable energy technologies with emphasis on biomass and solar thermal systems for heating applications in residential buildings. More specifically, and aiming at the maximum possible contribution of renewable energy sources in the total final energy consumption for the needs of zero energy buildings, different scenarios are presented based on a Life Cycle Energy Analysis (LCEA) approach. The methodology is based on quantifying the environmental impacts (midpoint analysis), as well as endpoint analysis, in order to define the impact on human health, ecosystem damage, and resource depletion. The LCEA has been conducted, supported by the SimaPro tool, ensuring the environmental impact assessment result. A combination of RES technologies based on solar and biomass are examined and compared to conventional fossil fuel heating systems according to technical, energy, and environmental criteria. Finally, the energy system technologies were compared in correlation to a building’s thermal insulation level. The first set of simulations fulfilled the minimum thermal insulation requirements, according to the national energy performance regulation, whilst the second set of simulations was based on increased levels of insulation. The point of this analysis was to correlate the impact of thermal insulation to RES technologies’ contribution. The results determined that the best available energy solution, focusing on technical and environmental criteria, is the combination of biomass and solar thermal systems for covering the heating processes in residential buildings. More specifically, the combined biomass–solar system has a lower overall environmental impact, due to the reduction in gaseous pollutant emissions, as well as the reduction in the amount of used fuel. The reduction in the total environmental impact amounts to a percentage of approximately 43%.

Review on nanofluids and machine learning applications for thermoelectric energy conversion in renewable energy systems

Open AccessCCS ChemistryRESEARCH ARTICLE27 May 2022Controllable Polymerization of N-Substituted β-Alanine N-Thiocarboxyanhydrides for Convenient Synthesis of Functional Poly(β-peptoid)s Ximian Xiao†, Min Zhou†, Zihao Cong, Longqiang Liu, Jingcheng Zou, Zhemin Ji, Ruxin Cui, Yueming Wu, Haodong Zhang, Sheng Chen, Maoquan Li and Runhui Liu Ximian Xiao† State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237 , Min Zhou† State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237 , Zihao Cong Key Laboratory for Ultrafine Materials of Ministry of Education, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, Research Center for Biomedical Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 , Longqiang Liu Key Laboratory for Ultrafine Materials of Ministry of Education, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, Research Center for Biomedical Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 , Jingcheng Zou Key Laboratory for Ultrafine Materials of Ministry of Education, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, Research Center for Biomedical Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 , Zhemin Ji Key Laboratory for Ultrafine Materials of Ministry of Education, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, Research Center for Biomedical Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 , Ruxin Cui Key Laboratory for Ultrafine Materials of Ministry of Education, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, Research Center for Biomedical Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 , Yueming Wu Key Laboratory for Ultrafine Materials of Ministry of Education, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, Research Center for Biomedical Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 , Haodong Zhang Key Laboratory for Ultrafine Materials of Ministry of Education, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, Research Center for Biomedical Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 , Sheng Chen Key Laboratory for Ultrafine Materials of Ministry of Education, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, Research Center for Biomedical Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 , Maoquan Li Department of Interventional and Vascular Surgery, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072 and Runhui Liu *Corresponding author: E-mail Address: [email protected] State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237 Key Laboratory for Ultrafine Materials of Ministry of Education, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, Research Center for Biomedical Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 https://doi.org/10.31635/ccschem.022.202201840 SectionsSupplemental MaterialAboutAbstractPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareFacebookTwitterLinked InEmail Poly(β-peptoid) is a class of polypeptide mimics that possesses excellent biocompatibility and resistance to proteolysis. However, the synthesis of poly(β-peptoid)s with functionalities is a long-standing challenge that greatly hinders the functional study and application of poly(β-peptoid)s. We report a controllable and easy synthesis of poly(β-peptoid)s bearing diverse functionalities via the ring-opening polymerization on N-substituted β-alanine N-thiocarboxyanhydrides (β-NNTAs). The polymerization can be carried out in open vessels under mild conditions using amines as the initiators to provide poly(β-peptoid)s with targeted molecular weights, narrow dispersities, and diverse functionalities in the side chains and termini. The β-NNTAs polymerization is even compatible with initiators bearing unprotected hydroxyl groups. The amphiphilic/cationic poly(β-peptoid)s exhibit a broad spectrum and potent antibacterial activities against multidrug-resistant bacteria. In addition, the highly favored stability of β-NNTA monomers for purification and storage highlights the advantages of this β-NNTA polymerization strategy for poly(β-peptoid)s synthesis, functional study, and application as a synthetic mimic of polypeptides. Download figure Download PowerPoint Introduction Poly(β-peptoid)s, as a class of polypeptide mimics, have a polyamide backbone similar to polypeptides but with an extra methylene group and with the proton of nitrogen–hydrogen bond in the backbone substituted by an alkyl group.1–4 Poly(β-peptoid)s have superior biocompatibility and excellent stability against proteolysis and therefore demonstrate promising biological applications in biomimetic scaffolds,3 antifouling properties,5 and antibacterials.6 However, the lack of an effective synthetic strategy is the long-standing challenge that greatly hinders the advance of this field and the application of poly(β-peptoid)s. Conventional solid-phase synthesis is applied to prepare poly(β-peptoid)s using either direct amide bond formation or via aza-Michael addition.7,8 However, no poly(β-peptoid)s with over 10 residues can be obtained using the solid-phase synthesis due to the low efficiency of this chemistry. Compared with the preparation of polypeptides and poly(α-peptoid)s, it is hard to obtain structurally diverse and functional poly(β-peptoid)s. Current solid-phase synthesis of poly(β-peptoid)s is also time-consuming, expensive, and difficult in scale up.9 To overcome the shortcomings of solid-phase synthesis in preparing poly(β-peptoid)s, polymerization strategies have been explored. Jia et al. reported a successful synthesis of poly(β-peptoid)s from the copolymerization of N-alkylaziridines and carbon monoxide using cobalt catalysts (Figure 1a).1,10 Nevertheless, this polymerization relies on high-pressure reaction conditions and a metal catalyst. Since 1954, to realize a mild synthesis of poly(β-peptoid)s, amine-initiated polymerization on N-substituted β-alanine N-carboxyanhydrides (β-NNCAs) has been explored (Figure 1b).2,11,12 However, this strategy suffers from the instability of β-NNCA monomers.12 In addition, the above two polymerization strategies for poly(β-peptoid)s synthesis are both highly sensitive to moisture and have structural diversity limited to N-alkyl and/or N-aryl substitution, which has been a serious obstacle to the synthesis, functional study, and application of poly(β-peptoid)s. Therefore, we need to develop a convenient, mild, and open vessel synthesis of poly(β-peptoid)s. Meanwhile, it is also vital to explore structurally diverse poly(β-peptoid)s for their functions and applications. Figure 1 | Polymerization strategy for the synthesis of poly(β-peptoid)s. Download figure Download PowerPoint Herein, we report the synthesis of poly(β-peptoid)s from a controllable ring-opening polymerization on N-substituted β-alanine N-thiocarboxyanhydrides (β-NNTAs) (Figure 1c). This controllable and living polymerization on β-NNTAs can be achieved using variable amines as the initiator to obtain poly(β-peptoid)s with predictable molecular weight (Mn) controllable degree of polymerization (DP) and low dispersity (Đ) without using any catalyst. This polymerization can be operated conveniently in an open vessel. Moreover, β-NNTA monomers can be easily obtained with a variety of N-substitutions, which enables a breakthrough in the structural diversity of resulting poly(β-peptoid)s. In addition, a variety of terminal functional groups can be introduced into poly(β-peptoid)s via the amine initiators. This strategy for poly(β-peptoid)s synthesis from controllable and living polymerization on β-NNTAs addresses the long-lasting challenges in this field and provides a convenient alternative to facilitate the synthesis, functional study, and application of poly(β-peptoid)s. Experimental Methods All reagents and solvents were purchased from Adamas Chemical Reagent Co., Ltd. (Shanghai, China) and used as received unless otherwise specified. Petroleum ether (PE), ethyl acetate (EtOAc), N,N-dimethylformamide (DMF), tetrahydrofuran (THF), toluene (Tol), acetonitrile (MeCN), dioxane, dimethyl sulfoxide (DMSO), and 1-methyl-2-pyrrolidinone (NMP) were purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd. and used as received without purification. Synthesized intermediates were purified using a SepaBean machine equipped with Sepaflash columns produced by Santai Technologies (Changzhou, China) Co. Ltd. Nuclear magnetic resonance (NMR) spectra were collected on a Bruker spectrometer at 400 MHz or 600 MHz, using CDCl3 or CF3COOD as solvents. Chemical shifts are referenced to residual protons in the deuterated NMR solvents. High-resolution electrospray ionization time-of-flight mass spectrometry (HRESI-TOF-MS) was collected on a Waters Xevo G2 TOF mass spectrometer (Waters Technologies Shanghai Ltd) and high-resolution electron ionization time-of-flight mass spectrometry (HREI-TOF-MS) was collected on a Waters GCT. High-performance liquid chromatography (HPLC) analysis was carried out on a Shimadzu LC-20AR HPLC System (Shimadzu (Shanghai) Global Laboratory Consumables Co., Ltd.) equipped with a Gemini 5 μm NX-C18 column. Gel permeation chromatography (GPC) was performed on a Waters GPC instrument equipped with a Brookhaven BI-MwA multiangle light-scattering detector (BI-MwA, Brookhaven Instruments Shanghai Representative Office) and a refractive index detector (Waters 2414) using DMF, supplemented with 0.01 M LiBr, as the mobile phase at a flow rate of 1 mL/min at 50 °C. The GPC were equipped by a Tosoh TSKgel Alpha-2500 column (particle size 7 μm), a Tosoh TSKgel Alpha-3000 column (particle size 7 μm), and a Tosoh TSKgel Alpha-4000 column (particle size 10 μm, 300 × 7.8 mm) linked in series. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) experiments were conducted on an AB Sciex 4800 Plus MALDI TOF/TOF analyzer (Shanghai AB Sciex Analytical Instrument Trading Co., Ltd.) using a 355 nm laser, a Shimadzu MALDI-7090TM TOF-TOF mass spectrometer (Shimadzu (Shanghai) Global Laboratory Consumables Co., Ltd.) with 2,5-dihydroxybenzoic acid (DHB) as the matrix. Dynamic light scattering (DLS) measurements were used to measure hydrodynamic diameters of assembled polymers using a Zetasizer Nano-ZS instrument, Model ZEN3600 (Malvern Instruments Ltd., Malvern, United Kingdom). Transmission electron microscopy (TEM) measurements were conducted using a JEOL JEM-1400 TEM (JEOL (Beijing) Co., Ltd. Shanghai Branch) at an acceleration voltage of 100 kV. Time-lapse fluorescent confocal imaging was performed using a Leica TCS SP8 system (Leica Microsystems) equipped with LAS X v3.5.2. software (Leica Microsystems) for acquisition control. Fluorescence spectra of the samples were performed on a Varian Cary Eclipse fluorescence spectrophotometer (Varian China Ltd., Shanghai Office). Results and Discussion Using pFBn β-NNTA ( 1a) as a model, we conducted the ring-opening polymerization on β-NNTA using 4-tert-butylbenzylamine (tBuBnNH2) as the initiator in variable solvents including DMF, THF, Tol, dioxane, MeCN, DMSO, and NMP ( Supporting Information Scheme S13, Figure S1, Table S1). Poly(N-pFBn-β-ala) was successfully obtained in polymerization using most common solvents as a single peak of GPC trace with narrow dispersity (Đ = 1.04–1.11), except that a bimodal peak of GPC trace was observed for polymerization using DMSO and NMP as the solvent. Among all solvents that are compatible with β-NNTA polymerization, DMF afforded the resulting poly(β-peptoid) with a polymer length (obtained DP = 21) almost identical to the expectation (calculated DP = 20). Considering that DMF normally provides excellent solubility and is a widely used solvent for polypeptide and polypeptoid synthesis, we chose DMF as the solvent for continuous β-NNTA polymerization studies. To examine if the polymer length of amine-initiated β-NNTA polymerization is controllable, we tried the polymerization on pFBn β-NNTA ( 1a) in DMF using variable [M]0/[I]0 ratios. The results showed that poly(β-peptoid)s were obtained with an incrementally increased chain length from 22 mer (Mn = 4.1 kDa) to 150 mer (Mn = 27.1 kDa) with narrow dispersities (Đ = 1.18–1.20) and DP almost identical to the prediction (Table 1, entries 1–5, Figure 2a). These results demonstrate the excellent controllability of the β-NNTA polymerization. Kinetics study showed that the polymerization had an evolution of Mn that showed in linear correlation with monomer conversion and kept narrow dispersity (Đ = 1.09–1.18) throughout the whole process (Figure 2b). It is worth mentioning that the polymerization showed first-order kinetic characteristics (kp[I] = 0.018 h−1) and over 90% conversion of β-NNTA monomer within 14 h (Figure 2c). The polymerization on pFBn β-NNTA in DMF was completed within 20 h. Table 1 | Poly(β-peptoid)s Synthesized from β-NNTAs Polymerizationa Entry M M0/I Mn, th (kDa) Mn (kDa)b DPb Ðb 1 1a 20 3.7 4.1 22 1.19 2 1a 40 7.3 7.3 40 1.20 3 1a 80 14.6 14.6 80 1.19 4 1a 100 18.1 17.9 99 1.18 5 1a 150 27.0 27.1 150 1.20 6 1b 20 3.4 3.2c 19c 1.12d 7 1c 20 4.3 4.6 21 1.13 8 1d 40 7.4 7.2 39 1.18 9 1e 20 2.4 2.1c 17c 1.15d 10 1f 20 2.7 2.4 18 1.17 11 1g 20 2.7 3.6c 27c 1.08d 12 1h 20 4.8 3.3 14 1.09 13 1i 20 5.1 4.0 16 1.13 14 1a-r- 1d 40/40 14.6 13.9 76 1.17 15 1a1st 20 3.7 3.7 20 1.16 1d2nd 20 7.4 7.3 40 1.15 aAll polymerizations were conducted using tBuBnNH2 as initiator in a sealed vessel at 60 °C. [M]0 at 2 M for entry 5, [M]0 at 1 M for other entries. bMn, DP, and Đ were determined by GPC using DMF as the mobile phase at a flow rate of 1 mL/min. cMn and DP were determined by NMR. dĐ was determined by MALDI-TOF-MS. Mn,th is the theoretical number average molecular weight; Mn,obtained is the obtained number average molecular weight; DP is the obtained degree of polymerization; Đ means the dispersity. Figure 2 | (a) Plots of Mn and Đ as a function of the [M]0/[I]0 ratio for pFBn β-NNTA. Inset: Overlay of GPC profiles at different [M]0/[I]0 ratios corresponding to entries 1–5 in Table 1. (b) Profiles of Mn and Đ as a function of pFBn β-NNTA conversions at the [M]0/[I]0 ratio of 20/1. Inset: Overlay of GPC profiles at different monomer conversions. (c) Kinetic profiles of conversion and ln([M]0/[M]) vs time at the [M]0/[I]0 ratio for pFBn β-NNTA of 20/1 using tBuBnNH2 as the initiator. (d) GPC traces of the block copolymer corresponding to entry 15 in Table 1. (e) The ring-closure synthesis for β-NNTAs. Reaction condition: 1.0 equiv. PBr3, anhydrous CH2Cl2, 0 °C to r.t., 4 h. (f) The purification of Bu β-NNTA via silica gel chromatography (9:1 PE:EtOAc). (g) Stability analysis of β-NNTA and β-NNCA at r.t. (h) Open-vessel polymerization of ThEt β-NNTA at 2 g scale at 60 °C in DMF, [M]0 = 1 M. Mn, DP and Đ were determined by GPC. Download figure Download PowerPoint The side-chain functionality or structural diversity of peptide mimics plays an essential role in defining their activity, function, and application.13–17 However, for poly(β-peptoid)s, current synthetic strategies using either the copolymerization of N-alkylaziridines and carbon monoxide or the ring opening polymerization of β-NNCAs can only afford poly(β-peptoid)s with N-alkyl or N-aryl functional groups.1,2 This challenge encouraged us to explore the synthesis of functional poly(β-peptoid)s from the polymerization on β-NNTAs. Structurally diversified β-NNTAs were easily synthesized from primary amines (Figure 1c, β-NNTA 1a– 1i, Supporting Information Schemes S1–S10 and Figures S32–S57). In addition, tBuBnNH2 successfully initiated the polymerization of all those β-NNTAs in our study to afford corresponding poly(β-peptoid)s in narrow dispersities (Đ = 1.09–1.18) and with diversified structures or side-chain functional groups including aromatic groups (4-fluorobenzyl in pFBn β-NNTA, benzyl in Bn β-NNTA, (4-chlorophenyl)ethyl in pCPE β-NNTA), heterocycles in ThEt β-NNTA, alkyl groups (cyclopropyl in cPr β-NNTA, isobutyl in iBu β-NNTA, and n-butyl in Bu β-NNTA), carboxylates in Cbz-Et β-NNTA, and amines in Cbz-AE β-NNTA (Table 1, entries 1–13, Figure 2a, and Supporting Information Figures S2–S9). The β-NNTA polymerization was also feasible for copolymerization. A random copolymerization on the mixture of pFBn β-NNTA and ThEt β-NNTA afforded poly[(N-pFBn-β-ala)-r-(N-ThEt-β-ala)] with the expected polymer length (DP = 76) and a narrow dispersity (Đ = 1.17) (Table 1, entry 14, Supporting Information Scheme S14 and Figure S10). Sequential addition of pFBn β-NNTA and ThEt β-NNTA in one-pot synthesis gave the first block of poly(N-pFBn-β-ala) at 20 mer with a narrow dispersity (Đ = 1.16) and the expected final block copolymer poly(N-pFBn-β-ala)-b-poly(N-ThEt-β-ala) at 40 mer with a low dispersity (Đ = 1.15) (Table 1, entry 15, Figure 2d, and Supporting Information Scheme S15). All these results demonstrate that the amine-initiated β-NNTA polymerization has excellent controllability to prepare poly(β-peptoid)s with diversified structures and side-chain functionalities. The stability of β-NNTA is vital to its purification and storage, ultimately contributing to structural and functional diversity of poly(β-peptoid)s. We found that β-NNTA displayed stability superior to β-NNCA with the same side chain. It is worth mentioning that we can obtain all β-NNTAs with high yield (81−93%) during the ring-closing process via silica gel chromatography (Figure 2e). Purification of β-NNTA via silica gel chromatography makes it possible to easily obtain pure oily β-NNTA monomers (representative Bu β-NNTA in Figure 2f), whereas β-NNCA is less stable and will decompose on silica gel, making the purification of oily β-NNCA monomers a headache ( Supporting Information Scheme S11 and Figures S58–S60). In addition, during storage, the purity of β-NNTA such as pFBn β-NNTA was maintained above 99% over 27 days at room temperature and showed no significant decomposition even after half a year at −20 °C (Figure 2g, Supporting Information Figure S11), whereas the purity of the corresponding β-NNCA sharply decreased to 23% after 27 days (Figure 2g). The open-vessel polymerizations have been reported in the synthesis of polypeptides and polypeptoids.18–27 The excellent stability of β-NNTA encouraged us to explore its polymerization in an open flask outside of a glove box. A gram-scale β-NNTA polymerization was achieved successfully in an open flask to give the resulting poly(N-ThEt-β-ala)20 in 90.1% yield (Figure 2h). The living and controllable polymerization of β-NNTAs encouraged us to explore the reaction mechanism. We proposed that the polymerization is initiated by nucleophilic addition of primary amine at the C1 carbonyl in a β-NNTA ring, followed by the ring opening of β-NNTA and release of the small molecule carbonyl sulfide (COS) to give an intermediate 1 that has an N-terminal secondary amine as the reactive center to attack another β-NNTA for chain propagation (Figure 3a).24,26,28,29 To provide mechanistic insights into chain initiation and propagation, Fourier transform infrared (FT-IR) characterization on a 1∶1 molar ratio mixture of tBuBnNH2 and pFBn β-NNTA was conducted (Figure 3b). Compared with pFBn β-NNTA, an above 1∶1 mixture had a shifted signal of the C1 carbonyl group from 1715.9 to 1642.1 cm−1 (C1′ in the mixture). The disappearance of C2 carbonyl signal at 1648.8 cm−1 indicated the ring opening of β-NNTA and subsequent release of COS. In addition, proton NMR characterization of an immediately prepared mixture of pFBn β-NNTA and tBuBnNH2 solution in CDCl3 at variable ratios showed a reduction of Ha and Hb peaks in the β-NNTA ring and the emergence of upfield-shifted Ha′ and Hb′ peaks in the β-NNTA ring opening product simultaneously, which indicated a quick nucleophilic addition of tBuBnNH2 to the C1 carbonyl in the β-NNTA ring at the initiation step (Figure 3c). Figure 3 | (a) Proposed mechanism of primary amine-initiated β-NNTA polymerization. (b) FT-IR spectra of β-NNTA, tBuBnNH2 and a 1∶1 β-NNTA/tBuBnNH2 mixture (DMF, room temperature, [M]0=0.5 M). (c) Instantaneous 1H NMR titration spectra on a mixture of β-NNTA/tBuBnNH2 in variable ratio (CDCl3, 25°C. [M]0=0.2 M). (d) HRESI-TOF-MS analysis on the 1∶1 β-NNTA/tBuBnNH2 mixture (DMF, room temperature, [M]0=0.5 M). (e) MALDI-TOF-MS of poly(N-pFBn-β-ala)20 (entry 1 in Table 1) with the corresponding chemical structures. Download figure Download PowerPoint HRESI-TOF-MS characterization on the above 1∶1 mixture showed a clear spectrum and high intensity fragment at m/z 343.2187 for intermediate 1 (Figure 3d), consistent with the result in the above NMR analysis and confirming nucleophilic addition of tBuBnNH2 to the β-NNTA ring during initiation. This was further confirmed by examining the final poly(β-peptoid)s (poly(N-pFBn-β-ala)20) using MALDI-TOF-MS characterization. The 179 Da difference between peaks reflected successful incorporation of the β-peptoid residues. Specific mass corresponding to each peak revealed the incorporation of a C-terminal tBuBnNH group via nucleophilic addition during initiation (Figures 3a and 3e). These results echoed the controllable β-NNTA polymerization and living polymerization with a normal amine mechanism. The terminal functionalization is important for the structural diversity and function of peptide mimics, for instance, in bioactive molecule conjugation and fluorescence labelling.30–39 The aforementioned open-vessel polymerization encouraged us to further explore C-terminal functionalization in an open vessel ( Supporting Information Scheme S16). Using primary amines as the initiator for the ring-opening polymerization on β-NNTAs allows the easy incorporation of diverse functionalities into the C-terminal of poly(β-peptoid) chains including alkenyl, alkynyl, adamantane, bromophenyl, azide, protected thiol, protected amine, methoxy, polyethylene glycol (Figure 4a, 2a− 2j), unprotected base, unprotected hydroxyl groups, aggregation-induced emission luminogen (AIEgen), and aggregation-caused quenching (ACQ) fluorophore (Figures 4b and 4c, 2k− 2q). In addition to terminal all poly(β-peptoid)s were successfully synthesized with excellent of chain length and narrow dispersities (Đ = ( Supporting Information Figures Figure 4 | amine-initiated β-NNTA polymerization in an open vessel. (a) functional primary amines as C-terminal groups. (b) Representative primary amines with nucleophilic groups. (c) Functional of C-terminal poly(β-peptoid)s. Download figure Download PowerPoint is the polymerization on β-NNTAs can be initiated by primary amines that have an unprotected and hydroxyl group (Figure The of unprotected reactive groups of β-NNTA polymerization the synthesis of poly(β-peptoid)s with function groups without and This encouraged us to explore a β-NNTA polymerization using unprotected as the initiator. the polymerization also hydroxyl groups to give the expected poly(β-peptoid)s with a narrow dispersity (Đ = GPC and a terminal in the polymer chain as by (Figure 4c, Supporting Information Figure The poly(β-peptoid)s in the solvent of the application of this polymerization in (Figure 4c, This mild β-NNTA polymerization also us to poly(β-peptoid)s with terminal fluorescence groups such as the ( ( Supporting Information Scheme and Figures and and the fluorophore ( with the expected polymer length and low dispersity (Figure 4c, and 2q). and displayed and showed the intensity at 90% and which a application of this β-NNTA polymerization and resulting poly(β-peptoid)s for Poly(β-peptoid)s have backbone structures similar to and excellent stability against which the possible of poly(β-peptoid)s as a synthetic mimic of polypeptides for a variety of applications. However, current functional study and application of poly(β-peptoid)s are limited due to the obstacle of poly(β-peptoid) To the of our no antibacterial application of poly(β-peptoid)s has been due to the to poly(β-peptoid)s via The mild and controllable synthesis of poly(β-peptoid)s from β-NNTA polymerization enables us to prepare structurally diverse poly(β-peptoid)s for functional including Using Cbz-AE β-NNTA and pFBn β-NNTA as for we synthesized poly(β-peptoid)s that were of both the and the (4-fluorobenzyl with an incrementally increased ratio of the as synthetic mimics of (Figures and These poly(β-peptoid)s were obtained at 20 mer at low dispersities (Đ = (Figures and GPC traces in Supporting Information Figure Figure 5 | Open-vessel polymerization for synthesis of poly(β-peptoid)s for antibacterial studies. (a) A of poly(β-peptoid)s. (b) of poly(β-peptoid)s. (c) The of the poly(β-peptoid)s against 5 of bacteria. (d) GPC characterization of side-chain protected from different (e) The of obtained from different against (f) Time-lapse confocal fluorescence imaging on the between and in the of is 1 Download figure Download PowerPoint The obtained poly(β-peptoid)s were for their against including multidrug-resistant

Insights into maize starch degradation by high pressure homogenization treatment from molecular structure aspect

Assessment of innovation policy standards’ impact on local development of renewable energy in Palestinian local government units

In recent years, consumer preferences have shifted towards better-quality rice, particularly towards varieties with good eating quality. Texture is an extremely important attribute for cooked rice and has been used as an indicator for consumer acceptance. Cooked rice texture is affected by a wide range of factors, such as the amylose content, postharvest processing, the milling ratio, the cooking method, etc., but the actual molecular reasons for the texture of cooked rice grains are still unclear. Since texture has been defined as a multidimensional characteristic that only humans can perceive, define, and measure, sensory descriptive analysis is a useful tool for characterizing texture properties of cooked rice. However, the cost associated with training and maintaining a descriptive panel has prompted many researchers to evaluate less costly and less time-consuming approaches. The overall objectives of this thesis are to explore the molecular mechanisms for the hardness and stickiness of cooked rice grains, increase understanding of the human textural perception of cooked rice, and develop an improved instrumental method to evaluate and/or predict the texture of cooked rice. The first chapter of this thesis reviews current understanding of the texture of cooked rice, which involves the factors affecting rice texture, the evaluation methods for cooked rice texture, and the scientific questions generating from the literature review and associating to the overall objectives of this thesis. In chapter 2, statistically and causally meaningful relationships are established between starch molecular structure (the molecular size distribution of whole (branched) starch and the chain length distribution of debranched starch) and texture (hardness and stickiness) of cooked rice grains. The amounts of amylose chains with degree of polymerization (DP) 100-20000, and of long amylopectin chains, positively correlate with hardness, while amylopectin chains with DP<70 and amylose molecular size both show negative correlations with hardness (p<0.05). There is also a significant negative correlation between stickiness and the amounts of long amylopectin chains (p<0.01). For rices with similar amylose content, the amount of amylose chains with DP 1000-2000 positively correlates with hardness while size negatively correlates with hardness (p<0.05). This indicates for the first time that, regardless of amylose content, rice varieties with smaller amylose molecular sizes and with higher proportions of amylose chains with DP 1000-2000 have a harder texture after cooking. This can be rationalized in terms of viscosity effects of long chains. Chapter 3 presents the first molecular understanding of stickiness between cooked rice grains by measuring the leaching and molecular structural characteristics during rice cooking. We find (i) the molecular size of leached amylopectin is 30 times smaller than that of native amylopectin while (ii) that of leached amylose is 5 times smaller than that of native amylose, (iii) the chain-length distribution (CLD: the number of monomer units in a chain on the branched polymer) of leached amylopectin is similar to native amylopectin while (iv) the CLD of leached amylose is much narrower than that of the native amylose), and (v) mainly amylopectin, not amylose, leaches out of the granule and rice kernel during cooking. Stickiness is found to increase with decreasing amylose content in the whole grain, and, in the leachate, with increasing total amount of amylopectin, the proportion of short amylopectin chains, and amylopectin molecular size. A molecular adhesion mechanism is put forward to explain this result. This molecular structural mechanism provides a new tool for rice breeders to select cultivars with desirable palatability by quantifying the components and molecular structure of leached starch. Chapter 4 characterizes the cooked rice texture by descriptive sensory analysis and two instrumental methods (texture profile analysis (TPA) and dynamic rheological testing) using a set of 18 varieties of rice with a wide range in amylose content (0-30%). Panellists’ results indicate that hardness and stickiness are the two most discriminating attributes among 13 tested textural attributes. Consistency coefficient (K*) and loss tangent (tan δ) from dynamic frequency sweep are used to compare with hardness and stickiness tested by TPA and sensory panellists, showing that K* representing hardness and tan δ representing stickiness are both statistically and mechanistically meaningful. The instrumental method is rationalized in terms of starch structural differences between rices: a higher proportion of both amylose and long amylopectin branches with DP 70–100 causes a more elastic and less viscous texture, which is readily understood in terms of polymer dynamics in solution. Finally, conclusions are presented in Chapter 5, summarizing the mechanisms for the hardness and stickiness of cooked rice, the main achievements corresponding to the objectives of this thesis, and the potential application of this study for rice industry and rice breeders. Furthermore, future works, e.g. exploring the specific location of amylose molecules within starch granules, optimizing the reference samples for sensory training, learning the effect of mastication and saliva on the rheological properties of cooked rice, are also recommended.