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1.
Hair waste in large amount is produced in India from temples and saloons, India alone exported approximately 1 million kg of hair in 2010. Incineration and degradation of waste human hair leads to environmental concerns. The hydrothermal process is a conventional method for the production of hair hydrolysate. The hydrothermal process is carried out at a very high temperature and pressure, which causes the degradation of heat-sensitive essential amino acids, thereby depleting the nutritional value. This work deals with alkaline hydrolysis of human hair using acoustic and hydrodynamic cavitation, and comparison with the conventional method. The optimal operating conditions for highest efficiency was observed, for the hydrolysis of 1 g of sample hairs in 100 mL of solution, at 4:1 (KOH: hair) ratio, soaking time of 24 h, the ultrasonic power density of 600 W dm−3 (20 KHz frequency and input power 200 W) or hydrodynamic cavitation inlet pressure of 4 or 7 bars. Cavitation results in rupture of disulfide linkages in proteins and mechanical effects lead to cleavage of several hydrogen bonds breaking the keratin sheet structure in hair. Breakdown of bonds leads to a decrease in viscosity of the solution. 10% and 6% reduction in viscosity is obtained at optimal conditions for ultrasonic and hydrodynamic cavitation treatment, respectively. FTIR analysis of produced hair hydrolysate confirmed that the disulfide bonds in hair proteins are broken down during cavitation. The amino acid of hair hydrolysate, prepared using cavitation, has a relatively higher digestibility and nutritional value due to the enhancement of amino-acid content, confirmed using amino acid analysis. Cavitation assisted hair hydrolysate has a potential application in agricultural engineering as a fertilizer for improvement of the quality of the soil and land. Cavitation based hair hydrolysate can also be used as an environmentally friendly and economical source of essential amino acids and digestibles for animal or poultry feed.  相似文献   
2.
The effects of plasma functionalized water (PFW) and its combination with ultrasound (UPFW) on the functional and bioactive properties of small yellow croaker protein hydrolysates (SYPHs) produced from three enzymes were investigated. Fluorescence and UV–Vis spectroscopy indicated that SYPHs tended to unfold with increasing intensity and shift in wavelengths to more flexible conformations under PFW and UPFW treatments. Particle size distribution and microstructure analysis revealed that treatments could disrupt aggregation of protein molecules to increase the roughness, specific surface area, and decrease the particle size of peptides during hydrolysis. The partially denatured structure of SYPHs induced by treatments increased the susceptibility of the fish proteins to exogenous enzymes, thereby accelerating the hydrolytic process to yield peptides with improved solubility, decreased emulsifying and foaming properties, and improved enzyme-specific antioxidant properties. The results revealed that the functionality of SYPHs was influenced by the treatment method and the enzyme type employed.  相似文献   
3.
纤维素酶是一种有效的纤维质类物质水解催化剂,工业应用时可通过固定化纤维素酶来降低其成本。本文将烟曲霉原变种JCF产生的纤维素酶固定在MnO2纳米颗粒上。 MnO2可提高纤维素酶的活性,并充当一个更好的载体。采用扫描电镜表征了所制MnO2纳米粒子及其负载纤维素酶的表面性质,以傅里叶变换红外光谱分析了固定在MnO2纳米粒子上纤维素酶的官能团性质。纤维素酶在MnO2纳米粒子上最大的固定化效率为75%。考察了固定化纤维素酶的活性、操作pH值、温度、热稳定性和重复使用性等性质。结果表明,所制固定化酶的稳定性比游离酶更高。固定于MnO2纳米粒子上的纤维素酶可用于纤维质类物质的水解反应,且能在较宽的温度和pH值范围内使用。表征结果证实了该催化剂具有非常高的催化纤维素类物质水解的活性。  相似文献   
4.
Separation, analysis and recycling technologies are of high interest for our modern societies, where colloidal iron and aluminium (hydr)oxides have important applications. However, there are significant gaps in the fundamental understanding of how these phases form in real systems. Classical nucleation theory cannot account for many experimental observations, and there is a dichotomy between the chemistry of hydrolysing/condensating systems and the physical notion of supersaturation. Reviewing parts of the established and recent literature, we demonstrate that concepts of nonclassical nucleation pathways can overcome these issues. This broader, chemistry-based conceptual framework has a high potential for advancing current applications, and developing new strategies towards separation, analysis and recycling applications, which seem to be urgently required for the future.  相似文献   
5.
Environmentally benign ionic liquid [bmim]HSO4 was found suitable for conversion of nitriles into carboxylic acids under mild conditions with excellent purity.  相似文献   
6.
The dinuclear ZnII complex [Zn2L(DNBA)2]BPh4 · EtOH ( 1 ) (DNBA = 3,5‐dinitrobenzonic acid) with an asymmetric dinuclear ligand, N‐4‐methyl‐homopiperazine‐N′‐[N‐(2‐pyridylmethyl)‐N‐2‐(2‐pyridylethyl)amine]‐1,3‐diamino‐propan‐2‐ol (HL), was synthesized and characterized. Single crystal X‐ray crystallographic analysis shows that the coordination around the two ZnII ions in 1 is significantly asymmetric, and the distance between both atoms is 3.426 Å, which is close to the Zn···Zn distance in related natural dinuclear metalloenzymes. Phosphodiesterase activity of Zn2L in situ formed from a 2:1 mixture of Zn2+ ion and HL was investigated using bis(4‐nitrophenyl) phosphate (BNPP) as substrate. The pH dependence of the BNPP cleavage in aqueous buffer media reveals a bell‐shaped pH‐kobs profile with an optimum at about pH 7.9, which is parallel to the formation of the dinuclear species Zn2L‐OH obtained from the potentiometric titration. The catalytic rate constant (kcat) is 6.30 × 10–4 s–1 at pH 7.9 and 25 °C, which is approx. 108‐fold higher than that of the uncatalyzed reaction. The homopiperazine bound deprotonated Zn‐OH group is responsible for the hydrolysis reaction. The possible mechanism for the BNPP cleavage promoted by Zn2L is proposed on the basis of kinetic and spectral analysis.  相似文献   
7.
The reaction of silver acetate with cis-[PtI2(dbtp)2], where dbtp = 5,7-ditertbutyl-1,2,4-triazolo-[1,5-a]pyrimidine, yielded cis-[Pt(OOCCH3)2(dbtp)2]·dmf (1). The complex has been analyzed by multinuclear magnetic resonance (1H, 13C, 15N), IR, and Raman. The compound formed two rotamers in CDCl3 and its spatial structures have been optimized using computational calculation. It was found that head-to-tail rotamer (1a) is more stable than its head-to-head counterpart (1b). In vitro antiproliferative activity against four tumor cell lines (A549, T47D, FaDu, and A2780cis) revealed in all cases significant cytotoxicity (IC50 = 0.26–1.80 μM), possessing IC50 values at least fivefold lower than cisplatin, carboplatin, and oxaliplatin (except A2780cis). The remarkable in vitro activity against T47D and A2780cis suggested the ability to overcome cisplatin resistance in these types of tumor cells. In addition, in vitro toxicity was evaluated against BALB/3T3 and has shown that the lipophilic platinum(II) complex (1) inhibits cell proliferation weaker than cisplatin and oxaliplatin. Additionally, cis-[Pt(OOCCH3)2(dbtp)2]·dmf exhibited selective activity, in contrast to cisplatin or oxaliplatin.  相似文献   
8.
Utilization of biocatalysts with high accessibility and availability, which have recently been applied in the preparation of enantiomerically enriched starting materials and synthetic intermediates for natural product syntheses (mainly 2013–2017) are summarized in this review. The main contents are as follows: 1) recruitment of biocatalysts for the transformation of organic compounds; 2) special precautions for preparative-scale biocatalytic synthetic experiments; 3) asymmetric reduction of carbonyl substrates; 4) kinetic resolution of alcohol and carboxylate enantiomers; 5) desymmetrization of multifunctional alcohol and carboxylate substrates; and 6) recognition of remote and non-central chirality.  相似文献   
9.
This work is devoted to the elaboration of a practical scheme for the synthesis of dendritic derivatives of gallic acid containing a carboxylate-ω-alkylphosphonic acid group and three terminal promesogenic substituents. Two synthetic strategies toward the target compounds were examined that differ in the sequence of the introduction of the promesogenic units and ω-alkylphosphonic group.  相似文献   
10.
杨睿 《高分子科学》2014,32(2):230-235
The hydrothermal aging of poly(ethylene terephthalate)(PET) was investigated at 70 95 °C. A new method to investigate the hydrolysis degree of PET by Fourier transform infrared spectroscopy(FTIR) was proposed. The spectra during the hydrothermal aging were measured using attenuated total reflection accessory(ATR). Peak resolving of carbonyl regions was performed, and the ratio of two groups of bands representing carboxylic acids and esters respectively were calculated to show the hydrolysis degree of ester groups in PET. The acid/ester ratio shows exactly the same trend as the average chain scission number per unit mass at various temperatures and thus can be used as a parameter to characterize the hydrolysis and random chain scission of PET. This method related to the hydrolysis mechanism directly, is simple, fast and convenient compared to the traditional methods such as viscometry, end-group titration and size exclusion chromatography(SEC). It may also be useful in hydrolysis characterization of other polyesters.  相似文献   
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