Optimal Degree Of Substitution Research Articles

공공재적 상(prizes)을 갖는 Tullock 집단 경합 모형에 대한 소고

The rent-seeking contest theory of Tullock has been deriving a lot of studies on competitions between individuals and/or groups in various settings. Among them, we reviews several works that examine Tullock group contests with group-specific public-good prizes in order to enhance our understanding about the effect of the degree of substitution or complementarity between members in a group on their effort incentives for their group’s winning. We also reviews studies on the optimal degree of substitution (complementarity) that maximizes the objective function of a contest organizer and group members’ payoffs, respectively, and endogenous formation of groups in Tullock contest setting as well. This paper may provide helpful knowledge and information that can be referred to design solutions for alleviating wasteful resources spent on rent-seeking behavior in our society.

Facile design of novel nanocellulose-based gel polymer electrolyte for lithium-ion batteries application

Nanocellulose-based gel polymer electrolytes (GPEs) for lithium-ion batteries have attracted great attention due to their biodegradable and renewable precursors, high thermal stability, good mechanical strength and electrolyte wettability. However, their abundant hydroxyl groups lead to the precursor films of GPEs with dense morphology, which severely affect their electrolyte uptake ratio and electrochemical performance. In this work, we aim to pretreat cellulose nanofibrils (CNFs) by acetylation to not only introduce ester groups in the according GPE to improve its electrolyte absorption capacity but also reduce the amount of hydroxyl groups for a stable battery cycle performance. At the optimal degree of substitution (DS) value of 2.37, the generated acetylated CNF (GACNF-3) GPE exhibited the best electrolyte uptake capacity of 301%, ionic conductivity of 2.73 × 10−3 S cm−1, and Li+ ion transference number of 0.65. Due to the high transportation performance of Li+ ions, mechanical strength (tensile strength of 37.66 MPa), and flexibility (elongation of 10.55%), the interfacial resistance of Li/GACNF-3 GPE/Li was 152 Ω, which only increased to 170 Ω after storage for 18 days. In particular, the assembled Li/GPE/LiFePO4 battery demonstrated an initial discharge capacity of 153 mA h g−1 with capacity retention of 88.8% after 100 cycles at 0.2C. The proposed material design would provide a novel perspective for the development of polymer electrolyte for lithium-ion battery.

New Family of Argyrodite Thioantimonate Lithium Superionic Conductors.

We report on a new family of argyrodite lithium superionic conductors, as solid solutions Li6+xMxSb1-xS5I (M = Si, Ge, Sn), that exhibit superionic conductivity. These represent the first antimony argyrodites to date. Exploration of the series using a combination of single crystal X-ray and synchrotron/neutron powder diffraction, combined with impedance spectroscopy, reveals that an optimal degree of substitution (x), and substituent induces slight S2-/I- anion site disorder-but more importantly drives Li+ cation site disorder. The additional, delocalized Li-ion density is located in new high energy lattice sites that provide intermediate interstitial positions (local minima) for Li+ diffusion and activate concerted ion migration, leading to a low activation energy of 0.25 eV. Excellent room temperature ionic conductivity of 14.8 mS·cm-1 is exhibited for cold-pressed pellets-up to 24 mS·cm-1 for sintered pellets-among the highest values reported to date. This enables all-solid-state battery prototypes that exhibit promising properties. Furthermore, even at -78 °C, suitable bulk ionic conductivity of the electrolyte is retained (0.25 mS·cm-1). Selected thioantimonate iodides demonstrate good compatibility with Li metal, sustaining over 1000 h of Li stripping/plating at current densities up to 0.6 mA·cm-2. The significantly enhanced Li ion conduction and lowered activation energy barrier with increasing site disorder reveals an important strategy toward the development of superionic conductors.

Study on preparation and physicochemical properties of hydroxypropylated starch with different degree of substitution under microwave assistance

Compared with the traditional method, the microwave assisted method can greatly shorten the reaction time of hydroxypropyl starch and improve product quality. The microwave assisted conditions and physicochemical properties of natural corn starch were studied. Response surface methodology was used to optimize the reaction conditions of three-level-three-factorial center composite design. The optimum parameters were as follows: the additive amount of propylene oxide was 8%, the radiation time was 6.08 min, and the microwave power was 303.43 W. The optimal degree of substitution (DS) of hydroxypropyl starch was determined by the optimal conditions predicted by RSM, which was 0.0729 mg/g. The analysis of physicochemical properties showed that with the increase of the DS of starch derivatives, the transparency (4% to 8.81%), the volume ratio of the condensing volume (21.11% to 33.11%), the hydrophilic (0.73 g/g to 2.46 g/g), and the hydrophobicity (0.67 g/g to 1.01 g/g), and the water evolution rate (46.91% to 36.16%) decreased. Fourier transform infrared spectroscopy showed that the enhancement of peak intensity at 1149 cm−1 indicated the successful introduction of hydroxypropyl group. Scanning electron microscopy showed that the surface morphology of corn starch was affected to some extent. The modification did not change the crystalline type of starch, which was still A type.

Development of fast dispersing tablets of nebivolol: experimental and computational approaches to study formulation characteristics

Formulation of FDT (fast dispersing tablets) of nebivolol was optimized and evaluated using simplex lattice design (SLD). The influence of type and concentration of three disintegrants viz.,Ac-Di-Sol, Primojel and Polyplasdone XL on hardness, friability and disintegration time of tablet was studied. Response surface plot and the polynomial equations were used to evaluate influence of polymer on the tablet properties. Results were statistically analyzed using ANOVA, and a p < 0.05 was considered statistically significant. Results reveal that fibrous integrity and optimal degree of substitution in Primojel and Ac-Di-Sol are mainly responsible for the hardness of the tablet. Use of Polyplasdone in higher percentage in tablet formulation may result in high friability. Increase in concentration of Ac-Di-Sol increases the disintegration time but increased concentration of Primojel in the tablet formulation decreases the disintegration time. This is also evident from model terms for disintegration time with a high 'F' value of 14.69 and 'p' value of 0.0031 (<0.05). The reason could be that Primojel has higher swelling properties and an optimum hydration capacity, which favors fast disintegration of a tablet. In conclusion, careful selection of disintegrant for FDT could improve their properties. Use of Simplex Lattice Design for formulation development could simplify the formulation process and reduce the production cost.

Synthesis, characterisation and in vitro digestibility of carboxymethyl potato starch rapidly prepared with microwave-assistance

Carboxymethyl potato starch was synthesised with the aid of microwave. Optimal degree of substitution (DS) of 0.32 was obtained at 45 °C in 25 min using aqueous ethanol media with water/solvent of 0.15 at 200 W. The molar ratio of sodium hydroxide and monochloroacetic acid to anhydroglucose unit for optimal DS were 2.5 and 1.0, respectively. FT-IR spectrometry revealed the carboxymethyl starch to show new bands at ν = 1614 cm−1 and ν = 1429 cm−1. Wide angle X-ray diffractometry and DSC revealed a remarkable reduction in starch crystallinity after carboxymethylation, which was consistent with destroyed surface observed in SEM. The digestibility of carboxymethyl starch (CMS) was lower than that of native starch. With similar DS, there was no difference in digestibility of carboxymethyl starch prepared with and without microwave. As DS increased from 0.05 to 0.32, the amount of resistant starch in microwave-assisted carboxymethyl starch was elevated from 14.6% to 20.0%, which was much higher than that of native starch (10.8%).

Synthesis and properties of carboxymethyl kudzu root starch

Carboxymethyl kudzu root starch was synthesized for the first time under different reaction conditions. Optimal degree of substitution (DS) of 0.92 and reaction efficiency (RE) of 66.1% were obtained at 40 °C, 3 h in isopropanol–water reaction mixture ratio 1:0.08. The ratio of sodium hydroxide and sodium monochloroacetate moles to anhydroglucose unit moles for the optimal DS and RE were 2.02 and 1.39. The influence of sodium hydroxide concentration, sodium monochloroacetate concentration, and water content, type of organic solvent, reaction time, and temperature were evaluated for degree of substitution (DS) and reaction efficiency (RE). Wide angle X-ray diffractometry revealed that starch crystallinity was reduced after carboxymethylation. Both thermogravimetry (TG) and derivative thermogravimetry (DTG) results show that thermal stability improved after carboxymethylation. IR spectrometry showed new bands at ν = 1597, 1415, and 1323 cm −1 when starch underwent carboxymethylation. The broad-band 13C NMR spectra of the ultrasonically degraded carboxymethyl starch showed a peak at δ = 177.85 ppm which was assigned to carbonyl carbon.

Flocculation of kaolin by waxy maize starch phosphates

Waxy maize starch phosphates were tested as flocculants in order to determine if they have the potential to replace petroleum-based polymer flocculants currently used commercially. Phosphorylation was carried out by dry heating of starches and sodium orthophosphates at 140 °C for 4 h. Native and phosphorylated waxy maize starches were ineffective as flocculants for kaolin in deionized water. However, in the presence of small amounts of Ca 2+ (1–4 mM), starch phosphates were effective flocculants of kaolin at concentrations as low at 3–4 ppm. The optimal degree of substitution (DS) for flocculation was 0.024 but the effect of DS was rather small over the range DS 0.007–0.08. Although a common synthetic polymer flocculant (polyacrylamide- co-acrylic acid) was effective at 1 ppm, the lower cost of starches should make them economically competitive.

Single and multi-step carboxymethylation of water yam ( Dioscorea alata) starch: Synthesis and characterization

Water yam ( Dioscorea alata) starch was carboxymethylated by single and multi-step processes for nine times successively. Optimal degree of substitution (DS) of 0.98 and reaction efficiency (RE) of 70.5% were obtained in the single-step carboxymethylation at 40 °C, 3 h in isopropanol–water reaction mixture ratio 1:0.16. The ratio of sodium hydroxide and sodium monochloroacetate moles to anhydroglucose unit moles for the optimal DS and RE were 1.62 and 1.39, respectively. The DS increased progressively as the steps of carboxymethylation increased from 2 to 9 and an optimal DS of 2.24 was obtained. Initial increases in carboxymethylation step increased the RE progressively up to 82.1% after the seventh carboxymethylation step but declined with further increases in the carboxymethylation step. The wide angle X-ray diffractometry and the DSC revealed remarkable changes after carboxymethylation because starch crystallinity reduced significantly. Thermogram of native starch showed a characteristic three-step decomposition with 13.16%, 61.54% and 24.79% weight losses progressively while carboxymethyl derivative showed four decomposition stages with 9.86%, 36.57%, 3.04% and 23.07% weight losses progressively. Studies revealed that carboxymethylation improved thermal stability of the native starch. IR spectrometry revealed that carboxymethyl starch showed new bands at ν = 1600, 1426 and 1324 cm −1. The broad band 13C NMR spectra of the ultrasonically degraded carboxymethyl starch showed a peak at δ = 180 ppm which was assigned to carbonyl carbon.