Enhanced efficiencies on purifying acid mine drainage in constructed wetlands based on synergistic adsorption of attapulgite-soda residue composites and microbial sulfate reduction.

Constructed wetlands (CWs) are a promising approach for treating acid mine drainage (AMD). However, the extreme acidity and high loads of heavy metals in AMD can easily lead to the collapse of CWs without proper pre-treatment. Therefore, it is considered essential to maintain efficient and stable performance for AMD treatment in CWs. In this study, pre-prepared attapulgite-soda residue (ASR) composites were used to improve the substrate of CWs. Compared with CWs filled with gravel (CWs-G), the removal efficiencies of sulfate and Fe, Mn, Cu, Zn Cd and Pb in CWs filled with ASR composites (CWs-ASR) were increased by 30% and 10-70%, respectively. These metals were mainly retained in the substrate in stable forms, such as carbonate-, Fe/Mn (oxide)hydroxide-, and sulfide-bound forms. Additionally, higher levels of photosynthetic pigments and antioxidant enzyme activities in plants, along with a richer microbial community, were observed in CWs-ASR than in CWs-G. The application of ASR composites alleviated the adverse effects of AMD stresses on wetland plants and microorganisms. In return, the increased bacteria abundance, particularly SRB genera (e.g., Thermodesulfovibrionia and Desulfobacca), promoted the formation of metal sulfides, enabling the saturated ASR adsorbed with metals to regenerate and continuously capture heavy metals. The synergistic adsorption of ASR composites and microbial sulfate reduction maintained the stable and efficient operation of CWs. This study contributes to the resource utilization of industrial alkaline by-products and promotes the breakthrough of new techniques for low-cost and passive treatment systems such as CWs.

Acid-catalyzed phenolation of lignin with tea polyphenol: Enhancing uv resistance and oxidation resistance for potential applications.

The rapid development of the industry has led to the destruction of the earth's ozone layer, resulting in an increasingly serious problem of excessive ultraviolet radiation. Exploring effective measures to address these problems has become a hot topic. Lignin shows promise in the design and preparation of anti-ultraviolet products due to its inherent properties. However, it is important to investigate way to enhance the reactivity of lignin and determine its application form in related products. In this study, phenolic reactions with tea polyphenols were conducted through acid-catalyzed conversion, utilizing organic solvent lignin as the primary material. The phenolic hydroxyl content of the original lignin increased significantly by 218.8 %, resulting in notable improvements in UV resistance and oxidation resistance for phenolic lignin. Additionally, micro-nanocapsule emulsions were formed using phenolic lignin particles as surfactants through ultrasonic cavitation with small-molecule sunscreens. A bio-based sunscreen was prepared with phenolated lignin micro-nanocapsules as the active ingredient, achieving an SPF 100.2 and demonstrating excellent stability. The sunscreen also exhibited strong antioxidant properties and impermeability, ensuring user safety. This research offers a current solution for improving the application of lignin in sunscreens while also broadening the potential uses of plant-based materials in advanced functional products.

Experimental research on the influence of acid on the chemical and pore structure evolution characteristics of Wenjiaba tectonic coal.

The chemical and pore structures of coal play a crucial role in determining the content of free gas in coal reservoirs. This study focuses on investigating the impact of acidification transformation on the micro-physical and chemical structure characteristics of coal samples collected from Wenjiaba No. 1 Mine in Guizhou. The research involves a semi-quantitative analysis of the chemical structure parameters and crystal structure of coal samples before and after acidification using Fourier Transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) experiments. Additionally, the evolution characteristics of the pore structure are characterized through high-pressure mercury injection (HP-MIP), low-temperature nitrogen adsorption (LT-N2A), and scanning electron microscopy (SEM). The experimental findings reveal that the acid solution modifies the structural features of coal samples, weakening certain vibrational structures and altering the chemical composition. Specifically, the asymmetric vibration structure of aliphatic CH2, the asymmetric vibration of aliphatic CH3, and the symmetric vibration of CH2 are affected. This leads to a decrease in the contents of -OH and -NH functional groups while increasing aromatic structures. The crystal structure of coal samples primarily dissolves transversely after acidification, affecting intergranular spacing and average height. Acid treatment corrodes mineral particles within coal sample cracks, augmenting porosity, average pore diameter, and the ratio of macro-pores to transitional pores. Moreover, acidification increases fracture width and texture, enhancing the connectivity of the fracture structure in coal samples. These findings provide theoretical insights for optimizing coalbed methane (CBM) extraction and gas control strategies.

Accelerated corrosion of low carbon steel by oscillatory acidic streams generated with a bio-inspired claw device.

A mechanical device inspired by the pistol shrimp snapper claw was developed. This technology features a claw characterized by a periodic opening/closing motion, at a controlled frequency, capable of producing oscillating flows at transitional Reynolds numbers. An innovative method was also proposed for determining the corrosion rate of carbon steel samples under oscillating acidic streams (aqueous solution of HCl). By employing very-thin carbon steel specimens (25 µm thickness), with one side coated with Zn and not exposed to the stream, it became possible to electrochemically sense the Zn surface once the steel sample was perforated, thus providing the average dissolution rate into the most relevant pit on the steel surface. Furthermore, a laser light positioned beneath the metallic sample, along with a camera programmed to periodically capture images of the steel surface, facilitated the accurate counting of the number of newly formed pits. The system consisting of the thin steel sample and the Zn coating can be seen as a type of corrosion sensor. Furthermore, the proposed laser illumination method allows corroborating the electrochemical detection of pits and also establishing their location. The techniques crafted in this study pave the way for developing alternative corrosion sensors that boast appealing attributes: affordability, compactness, and acceptable accuracy to detect in time and space localized damage.

Site-Directed Mutagenesis: Improving the Acid Resistance and Thermostability of Bacillus velezensis α-Amylase and Its Preliminary Feed Application.

The current study aimed to improve the acid resistance and thermostability of Bacillus velezensis α-amylase through site-directed mutagenesis, with a specific focus on its applicability to the feed industry. Four mutation sites, P546E, H572D, A614E, and K622E, were designed in the C domain of α-amylase, and three mutants, Mut1 (E), Mut2 (ED), and Mut3 (EDEE), were produced. The results showed that the specific activity of Mut3 was 50 U/mg higher than the original α-amylase (Ori) after incubation at 40 °C for 4 h. Compared to Ori, the acid resistance of Mut3 showed a twofold increase in specific activity at pH 2.0. Moreover, the results of preliminary feed hydrolysis were compared between Ori and Mut3 by designing three factors, three levels of orthogonal experiment for enzymatic hydrolysis time, feed quantity, and amount of amylase. It was observed that the enzymatic hydrolysis time and feed quantity showed an extremely significant difference (p < 0.01) in Mut3 compared to Ori. However, the amount of enzyme showed significant (p < 0.05) improvement in the enzymatic hydrolysis in Mut3 as compared to Ori. The study identified Mut3 as a promising candidate for the application of α-amylase in the feed industry.

Synergistic microwave and acidic deep eutectic solvent-based pretreatment of Theobroma cacao pod husk biomass for xylooligosaccharides production.

The bioconversion of lignocellulosic biomass into novel bioproducts is crucial for sustainable biorefineries, providing an integrated solution for circular economy objectives. The current study investigated a novel microwave-assisted acidic deep eutectic solvent (DES) pretreatment of waste cocoa pod husk (CPH) biomass to extract xylooligosaccharides (XOS). The sequential DES (choline chloride/citric acid, molar ratio 1:1) and microwave (450W) pretreatment of CPH biomass was effective in 67.3% xylan removal with a 52% XOS yield from total xylan. Among different XOS of varying degrees of polymerization, a higher xylobiose content corresponding to 69.3% of the total XOS (68.22 mg/g CPH) from liquid fraction was observed. Enzymatic hydrolysis of residual xylan from pretreated CPH biomass with low commercial xylanase (10 IU/g) concentration yielded 24.2% XOS. The MW-ChCl/citric acid synergistic pretreatment approach holds great promise for developing a cost-effective and environmentally friendly method contributing to the sustainable production of XOS from agricultural waste streams.

Alkene dialkylation by triple radical sorting.

The development of bimolecular homolytic substitution (SH2) catalysis has expanded cross-coupling chemistries by enabling the selective combination of any primary radical with any secondary or tertiary radical through a radical sorting mechanism1-8. Biomimetic9,10 SH2 catalysis can be used to merge common feedstock chemicals-such as alcohols, acids and halides-in various permutations for the construction of a single C(sp3)-C(sp3) bond. The ability to sort these two distinct radicals across commercially available alkenes in a three-component manner would enable the simultaneous construction of two C(sp3)-C(sp3) bonds, greatly accelerating access to complex molecules and drug-like chemical space11. However, the simultaneous in situ formation of electrophilic and primary nucleophilic radicals in the presence of unactivated alkenes is problematic, typically leading to statistical radical recombination, hydrogen atom transfer, disproportionation and other deleterious pathways12,13. Here we report the use of bimolecular homolytic substitution catalysis to sort an electrophilic radical and a nucleophilic radical across an unactivated alkene. This reaction involves the in situ formation of three distinct radical species, which are then differentiated by size and electronics, allowing for regioselective formation of the desired dialkylated products. This work accelerates access to pharmaceutically relevant C(sp3)-rich molecules and defines a distinct mechanistic approach for alkene dialkylation.

Quantification of Hop-Derived Bitter Compounds in Beer Using Liquid Chromatography Mass Spectrometry.

Hops (Humulus lupulus L.) are essential raw materials for beer brewing, and the major contributors to beer bitterness are isohumulones (iso-α-acids) and humulinones. In recent years, many breweries have focused on the production of hop-forward beer styles by adding hops after or during the cold fermentation stage, which will tend to release humulinones or other hop-derived bitter compounds. In this study, a LC-MS/MS method was developed for quantification of 60 hop-derived bitter compounds in 25 min. Reverse-phase chromatography with an alkaline methanol/acetonitrile (70:30) mobile phase was used for the separation. The quantitative range was 0.053-3912 ng/mL with correlation coefficient r > 0.99, and the LOQ were 0.26 and 0.053 ng/mL for iso-α-acids and humulinones. Precision (RSD < 5.0%) and accuracy (recovery 86.3%-118.1%) were both satisfactory. The abundance of hop-derived bitter compounds in the dry-hopped beer (Double-India Pale Ale) and the nondry-hopped beer (Vienna Lager) were monitored throughout the fermentation and storage stages, and the formation of oxidation and cyclization products showed difference profiles between these two beers. The quantification results reveal how hop-derived bitter compounds change throughout the brewing process, as well as the influence of hops and brewing techniques on beer bitterness.

Oxocarbon Acids and their Derivatives in Biological and Medicinal Chemistry.

The biological and medicinal chemistry of the oxocarbon acids 2,3- dihydroxycycloprop-2-en-1-one (deltic acid), 3,4-dihydroxycyclobut-3-ene-1,2-dione (squaric acid), 4,5-dihydroxy-4-cyclopentene-1,2,3-trione (croconic acid), 5,6-dihydroxycyclohex- 5-ene-1,2,3,4-tetrone (rhodizonic acid) and their derivatives is reviewed and their key chemical properties and reactions are discussed. Applications of these compounds as potential bioisosteres in biological and medicinal chemistry are examined. Reviewed areas include cell imaging, bioconjugation reactions, antiviral, antibacterial, anticancer, enzyme inhibition, and receptor pharmacology.

Physicochemical and thermal properties of pepsin- and acid-soluble collagen isolated from the body wall of sea cucumbers (Stichopus hermanni).

The main objective of this work was to characterize the acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) from the body wall of the sea cucumber scientifically called, Stichopus hermanni. For the extraction of ASC and PSC, the pre-treated sea cucumber body walls were subjected to 0.5 M acetic acid and 5 g L-1 pepsin, respectively. The yield of ASC (7.30% ± 0.30%) was found to be lower than the PSC (23.66% ± 0.15%), despite both ASC and PSC having similar chemical compositions except for the quantity of protein. The collagens produced from ASC and PSC show maximum peaks on ultraviolet-visible spectroscopic profiles at wavelengths of 230 and 235 nm, respectively, with no significant difference in the maximum temperature (Tmax ) of the extracted ASC and PSC. The ASC's coloration was whiter than that of the PSC. As a result, the collagen obtained from the body wall of the sea cucumber showed promise for usage as a substitute for collagen derived from marine sources. PRACTICAL APPLICATION: The two most popular methods of collagen extraction were acid hydrolysis and enzymatic hydrolysis. To determine whether the extracted collagen is a suitable substitute for animal collagen in different industries, it is required to characterize its physicochemical qualities. This study discovered a new application for marine collagen in the food industry: The sea cucumber has collagen with a greater yield in pepsin extraction with good physicochemical qualities.

Acidic Environment Induces Pyroptosis of NLRP3 Inflammatory Vesicle-Mediated Nucleus Pulposus Cells Through Up-Regulation of POSTN Expression

SUMMARY: Intervertebral disc degeneration (IVDD) is induced by nucleus pulposus (NP) dysfunction as a result of massive loss of NP cells. It has been reported that the acidic microenvironment of the intervertebral disc (IVD) can induce NP cell pyroptosis, and that up-regulation of periostin (POSTN) expression has a negative effect on NP cell survival. However, the relationship between the acidic environment, POSTN expression level and NP cell pyroptosis is unclear. Therefore, the aim of this study was to explore the relationship between acidic environment and POSTN expression level in NP cells, as well as the effect of POSTN in acidic environment on NP cell pyroptosis. NP cells were obtained from the lumbar vertebrae of Sprague Dawley (SD) male rats. These cells were divided into normal and acidic groups according to whether they were exposed to 6 mM lactic acid solution. And NP cells in the acidic group were additionally divided into three groups: (1) Blank group: no transfection; (2) NC group: cells transfected with empty vector plasmid; (3) sh-POSTN group: cells transfected with sh-POSTN plasmid to knock down the expression level of POSTN. Quantitative real-time PCR (qRT-PCR) and western blot was performed to assess the expression of POSTN at the mRNAand protein levels. CCK8 was used to evaluate cell survival. Western blot, in addition, was performed to examine acid-sensing ion channels (ASIC)-related proteins. And pyroptosis was detected by ELISA and western blot. The expression level of POSTN was significantly increased in NP cells in acidic environment. Knockdown of POSTN expression promoted the survival of NP cells in acidic environment and reduced the protein levels of ASIC3 and ASIC1a in NP cells. Moreover, knockdown of POSTN expression decreased the pyroptosis proportion of NP cells and the levels of pro-inflammatory cytokines interleukin (IL)-1β and IL-18. The levels of pyroptosis-related proteins NLRP3, ASC, cleaved-Caspase-1, and cleaved-GSDMD were also affected by the decreased POSTN expression. The extracellular acidic environment created by lactic acid solution activated NLRP3 inflammatory vesicle-induced caspase-1 to get involved in NP cell pyroptosis by up-regulating POSTN expression.

La degeneración del disco intervertebral (DDIV) es inducida por una disfunción del núcleo pulposo (NP) como resultado de una pérdida masiva de células NP. Se ha informado que el microambiente ácido del disco intervertebral (DIV) puede inducir la piroptosis de las células NP y que la regulación positiva de la expresión de periostina (POSTN) tiene un efecto negativo en la supervivencia de las células NP. Sin embargo, la relación entre el ambiente ácido, el nivel de expresión de POSTN y la piroptosis de las células NP es poco clara. Por lo tanto, el objetivo de este estudio fue explorar la relación entre el ambiente ácido y el nivel de expresión de POSTN en células NP, así como el efecto de POSTN en ambiente ácido sobre la piroptosis de las células NP. Las células NP se obtuvieron de las vertebras lumbares de ratas macho Sprague Dawley (SD). Estas células se dividieron en grupos normales y ácidos según se expusieron a una solución de ácido láctico 6 mM. Las células NP en el grupo ácido se dividieron adicionalmente en tres grupos: (1) Grupo en blanco: sin transfección; (2) grupo NC: células transfectadas con plásmido vector vacío; (3) grupo sh-POSTN: células transfectadas con plásmido sh-POSTN para reducir el nivel de expresión de POSTN. Se realizó una PCR cuantitativa en tiempo real (qRT-PCR) y una transferencia Western para evaluar la expresión de POSTN en los niveles de ARNm y proteína. Se utilizó CCK8 para evaluar la supervivencia celular. Además, se realizó una transferencia Western para examinar las proteínas relacionadas con los canales iónicos sensibles al ácido (ASIC). La piroptosis se detectó mediante ELISA y Western blot. El nivel de expresión de POSTN aumentó significativamente en células NP en ambiente ácido. La eliminación de la expresión de POSTN promovió la supervivencia de las células NP en un ambiente ácido y redujo los niveles de proteína de ASIC3 y ASIC1a en las células NP. Además, la eliminación de la expresión de POSTN disminuyó la proporción de piroptosis de las células NP y los niveles de citocinas proinflamatorias interleucina (IL) - 1β e IL-18. Los niveles de proteínas relacionadas con la piroptosis NLRP3, ASC, Caspasa-1 escindida y GSDMD escindida también se vieron afectados por la disminución de la expresión de POSTN. El ambiente ácido extracelular creado por la solución de ácido láctico activó la caspasa-1 inducida por vesículas inflamatorias NLRP3 para involucrarse en la piroptosis de las células NP mediante la regulación positiva de la expresión de POSTN.

Angiotensin-I-Converting Enzyme (ACE)-Inhibitory Peptides from the Collagens of Monkfish (Lophius litulon) Swim Bladders: Isolation, Characterization, Molecular Docking Analysis and Activity Evaluation.

The objective of this study was to isolate and characterize collagen and angiotensin-I-converting enzyme (ACE)-inhibitory (ACEi) peptides from the swim bladders of monkfish (Lophius litulon). Therefore, acid-soluble collagen (ASC-M) and pepsin-soluble collagen (PSC-M) with yields of 4.27 ± 0.22% and 9.54 ± 0.51%, respectively, were extracted from monkfish swim bladders using acid and enzyme methods. The ASC-M and PSC-M contained Gly (325.2 and 314.9 residues/1000 residues, respectively) as the major amino acid, but they had low imino acid content (192.5 and 188.6 residues/1000 residues, respectively) in comparison with collagen from calf skins (CSC) (216.6 residues/1000 residues). The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) patterns and ultraviolet (UV) absorption spectrums of ASC-M and PSC-M illustrated that they were mainly composed of type I collagen. Subsequently, three ACEi peptides were isolated from a PSC-M hydrolysate prepared via a double-enzyme system (alcalase + neutrase) and identified as SEGPK (MHP6), FDGPY (MHP7) and SPGPW (MHP9), with molecular weights of 516.5, 597.6 and 542.6 Da, respectively. SEGPK, FDGPY and SPGPW displayed remarkable anti-ACE activity, with IC50 values of 0.63, 0.94 and 0.71 mg/mL, respectively. Additionally, a molecular docking assay demonstrated that the affinities of SEGPK, FDGPY and SPGPW with ACE were -7.3, -10.9 and -9.4 kcal/mol, respectively. The remarkable ACEi activity of SEGPK, FDGPY and SPGPW was due to their connection with the active pockets and/or sites of ACE via hydrogen bonding, hydrophobic interaction and electrostatic force. Moreover, SEGPK, FDGPY and SPGPW could protect HUVECs by controlling levels of nitric oxide (NO) and endothelin-1 (ET-1). Therefore, this work provides an effective means for the preparation of collagens and novel ACEi peptides from monkfish swim bladders, and the prepared ACEi peptides, including SEGPK, FDGPY and SPGPW, could serve as natural functional components in the development of health care products to control hypertension.

Aspect elucidation of a physicochemical pretreatment for continuous decrystallization.

The purpose of this study is to understand the operating conditions of a physicochemical pretreatment process for lignocellulosic biomass using homogeneous acid catalysts. Four parameters were studied: moisture content, acid catalyst, type of biomass and reactor morphology. The different types of biomass (perennial grasses: sugarcane bagasse, corn stover; flowering plants: cannabis (stalks and leaves); hardwoods (pulp and bark): poplar, sugar maple; softwood bark) were processed in a meat grinder with sulfuric acid. Furthermore, softwood bark was used to change the moisture content, acid catalyst and reactor morphology. Biomass moisture above 17 wt% yielded less than 50 wt% glucose. Sulfuric acid, by far, had the best performance with a 74.5 wt% glucose yield in the meat grinder. The glucose yield showed a direct relationship with the non-carbohydrate components of biomass (lignin, ash, etc).

Organophosphorus-Catalyzed "Dual-Substrate Deoxygenation" Strategy for C-S Bond Formation from Sulfonyl Chlorides and Alcohols/Acids.

A green method to construct C-S bonds using sulfonyl chlorides and alcohols/acids via a PIII/PV═O catalytic system is reported. The organophosphorus-catalyzed umpolung reaction promotes us to propose the "dual-substrate deoxygenation" strategy. Herein, we adopt the "dual-substrate deoxygenation" strategy, which achieves the deoxygenation of sulfonyl chlorides and alcohols/acids to synthesize thioethers/thioesters driven by PIII/PV═O redox cycling. The catalytic method represents an operationally simple approach using stable phosphine oxide as a precatalyst and shows broad functional group tolerance. The potential application of this protocol is demonstrated by the late-stage diversification of drug analogues.

Brønsted Acid-Catalyzed Dehydrative Nazarov-Type Cyclization/C2-N1 Cleavage Cascade of Perfluoroalkylated 3-Indolyl(2-benzothienyl)methanols.

A novel and unprecedented p-toluenesulfonic acid-catalyzed dehydrative Nazarov-type cyclization/C2-N1 bond cleavage cascade reaction of perfluoroalkylated 3-indolyl(2-benzothienyl)methanols has been developed. This reaction provides an efficient and practical protocol for the construction of highly functionalized benzothiophene-fused cyclopentenones with exclusive stereoselectivity. In addition, this cascade transformation also delineates a rare example of the involvement of the selective C2-N1 bond cleavage of indoles.

Spectroscopic Signatures of Internal Hydrogen Bonds of Brønsted-Acid Sites in the Zeolite H-MFI.

The location of Brønsted-acid sites (bridging OH groups, b-OH) at different crystallographic positions of zeolite catalysts influences their reactivity due to varying confinement. Selecting the most stable b-OH conformers at each of the 12 T-sites (T=Si/Al) of H-MFI, a representative set of 26 conformers is obtained which includes free b-OH groups pointing into the empty pore space and b-OH groups forming H-bonds across five- or six-membered rings of TO4 tetrahedra. Chemically accurate coupled-cluster-quality calculations for periodic models show that the strength of internal H-bonds and, hence, the OH bond length vary substantially with the framework position. For 11 of the 19 H-bonded b-OH groups examined, our predictions fall into the full width at half maximum range of the experimental signals at 3250±175 cm-1 and 7.0±1.4 ppm which supports previously debated assignments of these signals to H-bonded b-OH sites.

Rapid and mild fractionation of hemicellulose through recyclable mandelic acid pretreatment.

The development of organic acid pretreatments from biological sources is essential to facilitate the progress of green and sustainable chemistry. In this study, the effectiveness of mandelic acid pretreatment (MAP) was analyzed for eucalyptus hemicellulose separation. 83.66% of xylose was separated under optimal conditions (temperature: 150 °C; concentration: 6.0 wt%; time: 80 min). The hemicellulose separation selectivity is higher than acetic acid pretreatment (AAP). The stable and effective separation efficiency (56.55%) is observed even after six reuses of the hydrolysate. Higher thermal stability, larger crystallinity index and optimized surface element distribution in the samples were demonstrated by MAP. Lignin condensation is effectively inhibited through MAP, as determined from the structural of different lignin. In particular, the demethoxylation of lignin by MA was found. These results open up a new way to construct a novel organic acid pretreatment for separating hemicellulose with high efficiency.

Implementing dilute acid pretreatment coupled with solid acid catalysis and enzymatic hydrolysis to improve bioconversion of bamboo shoot shells.

Exploiting bamboo shoot shells (BSS) as feedstocks for biorefining is a crucial scheme to advance the bioavailability of bamboo shoots. This work applied traditional dilute sulfuric acid pretreatment (DAP) to treat BSS and simultaneously prepared the solid-acid-catalyst by using BSS as carbon-based carriers. The biocatalysis of the prehydrolysate from DAP and enzymatic hydrolysis of pretreated BSS was subsequently performed to achieve efficient bioconversion of its carbohydrates. The results displayed that 0.1 g/L H2SO4 employed in DAP was the optimal condition for furfural conversion of BSS during biocatalysis, reaching the maximum of 41%. Meanwhile, the enzymatic hydrolysis efficiency of the pretreated BSS also reached the maximum of 97%. This increment of efficiency was ascribed to the enhancement of accessibility and cellulosic crystal size, and also the reduction of surface area of lignin in BSS. Ultimately, the efficient bioutilization of BSS and bioconversion of its carbohydrates were realized by DAP technology.

pH-equilibration of human hair: Kinetics and pH-dependence of the partition ratios for H+ - and OH- -ions based on a Freundlich isotherm.

Hair is an insoluble, fibrous, α-keratinous, protein composite material, providing outer coverage, e.g., for mammals. In the context of a wider study on the effects of pH on human hair properties, we investigated the time-dependence of pH-equilibration study across the acid and the basic pH-range, using appropriate pure solutions of hydrochloric acid and sodium hydroxide. The results show that pH-equilibration follows essentially equal 1st-order kinetics across the pH-range. The characteristic process time does not change significantly and is in the range of 2.5-5 h. The analysis enables to determine the equilibrium uptakes of H+- and OH- -ions. These follow the expected U-shaped path across the pH-range. For both acidic and alkaline conditions, data are well described by two very similar sorption isotherms of the Freundlich-type. In consequence, partition ratios for both ions are highest near neutrality (pH 7: >6000) and drop off strongly towards low and high pHs (<50). Hair is thus a very strong 'sink' for H+ and OH-. This observation fundamentally challenges traditional views of limited ion uptake, namely, in the mid-pH-range due to hindered diffusion. It also does not support considerations on special roles of certain pHs, specific groups of amino acids, or morphological components. Our analysis thus suggests that established views of the interaction of hair and pH need to be reconsidered, The Freundlich isotherm approach appears to provide a versatile tool to refine our understanding of the interactions of hair and possibly other keratinous materials (horn, nail, feathers) with acids and bases.

Extraction and Characterization of Pepsin- and Acid-Soluble Collagen from the Swim Bladders of Megalonibea fusca.

There is a growing demand for the identification of alternative sources of collagen not derived from land-dwelling animals. The present study explored the use of pepsin- and acid-based extraction protocols to isolate collagen from the swim bladders of Megalonibea fusca. After extraction, these acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) samples respectively were subjected to spectral analyses and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) characterization, revealing both to be comprised of type I collagen with a triple-helical structure. The imino acid content of these ASC and PSC samples was 195 and 199 residues per 1000 residues, respectively. Scanning electron microscopy demonstrated that samples of freeze-dried collagen exhibited a compact lamellar structure, while transmission electron microscopy and atomic force microscopy confirmed the ability of these collagens to undergo self-assembly into fibers. ASC samples exhibited a larger fiber diameter than the PSC samples. The solubility of both ASC and PSC was highest under acidic pH conditions. Neither ASC nor PSC caused any cytotoxicity when tested in vitro, which met one of the requirements for the biological evaluation of medical devices. Thus, collagen isolated from the swim bladders of Megalonibea fusca holds great promise as a potential alternative to mammalian collagen.