Effect Of pH Research Articles

Waste hazelnut shell based effective hydrothermal carbon/SnO2 nanoparticles: Towards electrochemical sensing of catechol in green tea, fruit juice, and urine samples

This study focused on the electrochemical detection of catechol (CC), a carcinogenic for humans and a periodic environmental pollutant found in consumed food and beverages and has low degradability and high toxicity in the ecological environment. Also, in this study, for the first time, a new and green electrochemical detection platform was developed for the detection of CC through green carbon material (HZ) recycled from waste hazelnut shells with the hydrothermal carbonization technique (HTC) and SnO2 nanoparticles (NPs). The morphology, surface chemistry, chemical structure, and physicochemical properties of the synthesized green-based functional carbon material and SnO2 NPs were thoroughly investigated and elucidated using different characterization techniques. Thus, a green perspective was contributed to the studies of researchers working on CC detection in designing new types of nanosensors and developing electrode modifications. On GCE with an HZ-SnO2 modification, the effects of pH, the supporting electrolyte, and the scan rate on the electrochemical behavior of CC were investigated. The limit of detection (LOD) of the proposed nanosensor for CC was determined as 8.51 nM and the linearity range was determined as 0.80–80 µM under optimal conditions using adsorptive stripping differential pulse voltammetry (AdsDPV).The developed new type, the green method, has been performed to detect the CC in green tea, fruit juice, and urine samples with sufficient accuracy and precision.

Unraveling the Oxidation Mechanism of Formic Acid on Pd(111) Electrode: Implication from pH Effect and H/D Kinetic Isotope Effect

Unraveling the Oxidation Mechanism of Formic Acid on Pd(111) Electrode: Implication from pH Effect and H/D Kinetic Isotope Effect

Programmed Lung Metastasis Immunotherapy via Cascade‐Responsive Cell Membrane‐Mimetic Copolymer‐Wrapped Nanoraspberry‐Mediated Elesclomol‐Copper Delivery

AbstractT lymphocytes play a central role in immunotherapy, utilizing physical interactions to actively inhibit the development of metastases. However, tumor immune privilege and heterogeneity pose challenges by protecting against immune attacks and limiting immune cell infiltration into tumors, particularly in invasive metastatic clusters. Here, a tumor penetrating magnetic particles (TUP) containing the cascade‐responsive cell membrane‐mimetic copolymer (zwitterionic 2‐methacryloyloxyethyl phosphorylcholine‐co‐3‐hydroxypyridin‐4‐one, PH) and cuproptosis molecules (elesclomol‐copper, EsCu) for programming T cell infiltration is developed. The intravenously injected TUP accumulates at the tumor via the charge conversion of PH and hyperthermia effects of TUP. In metastatic clusters, ES and Cu, triggered by intracellular environments and hyperthermia, are readily released. ES and Cu simultaneously induce cuproptosis of cancer cells and stimulate immune responses. This process destroys self‐defense mechanisms and exacerbates cytotoxicity. The therapies facilitate the release of tumor‐associated antigens, including neoantigens and damage‐associated molecular patterns. Following this, the 3‐hydroxypyridin‐4‐one groups on TUP act as antigen reservoirs, transporting autologous tumor‐associated antigens to dendritic cells, thereby inducing prolonged immune activation. TUP acts as an antigen reservoir in copper apoptosis‐mediated lung metastasis, promoting the accumulation of immune cells in metastatic clusters and effectively preventing the progression of metastatic tumors.

Effectively adsorb Au(S2O3)23- using aminoguanidine as trapping group from thiosulfate solutions.

Thiosulfate gold leaching is one of the most promising green cyanide-free gold extraction processes; however, the difficulty of recovering Au(I) from the leaching system hinders its further development. This study prepared aminoguanidine-functionalized microspheres (AGMs) via a one-step reaction involving nucleophilic substitution between aminoguanidine hydrochloride and chloromethylated polystyrene microspheres and used AGMs to adsorb Au(I) from thiosulfate solutions. Scanning electron microscopy, Brunauer-Emmett-Teller analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy were used to analyze the structure and properties of AGMs. Experiments were designed to investigate the effects of pH, temperature, initial Au(I), and thiosulfate concentrations on the gold adsorption performance of AGMs. Results demonstrated that AGMs can efficiently adsorb Au(I) from thiosulfate solutions in a wide pH range. The adsorption process conforms to the pseudo-second-order kinetic model and Langmuir isotherm model, with a maximum capacity of 22.03kg/t. Acidic thiourea is an effective desorbent, and after four adsorption-desorption cycles, the adsorption rate of Au(I) by AGMs is 78.63%, which shows AGMs have good cyclic application potential. Based on the results of characterization, experiments, and density functional theory calculations, the mechanism for the adsorption of [Au(S2O3)2]3- on AGMs involves anion exchange. Importantly, AGMs exhibited satisfactory adsorption property for Au(I) in practical Cu2+-NH3(en)-S2O32- systems. This study provided experimental reference for the recovery of Au(I) from thiosulfate solution.

Tailored Polymeric Carbon Nitride Coupled with Bi2O3 for Constructing Z‐Scheme Heterojunction with Enhanced Photocatalytic Activity

AbstractThe great demand for visible‐light‐induced catalysts with high photocatalytic performance has stimulated extensive interest in constructing g‐C3N4‐based Z‐Scheme heterojunctions. In this research work, the g‐C3N4/Bi2O3 Z‐Scheme heterojunction by precipitation‐hydrothermal method was constructed, and characterized by various techniques. The g‐C3N4/Bi2O3‐1 composite exhibited a transient photocurrent response approximately 7 and 5 times higher than that of bare g‐C3N4 and Bi2O3, respectively, and showed higher visible photocatalytic activity with 99.8 % degradation of methylene blue (MB) within 75 min. Meanwhile, the pH effect on the photocatalytic degradation of MB was investigated. Radicals trapping experiments showed that •OH free radical played a predominant role for the degradation of MB, EPR analysis confirmed the presence of superoxide radicals, which combined with the band structure of the composites, confirmed the Z‐Scheme of the heterojunction. A possible mechanism for photocatalytic degradation of MB dyes in g‐C3N4/Bi2O3‐1 composites was also proposed. This study provided a new avenue for the development of novel g‐C3N4‐based Z‐Scheme heterojunction materials with prospective applications in the fields of energy and environment.

Effect of Fermentation Time, pH, and Their Interaction on the Production of Volatile Fatty Acids from Cassava Wastewater

Acidogenic fermentation is a technology that involves halting methanogenesis in the conventional anaerobic digestion process to produce mainly volatile fatty acids (VFAs). VFAs serve as direct precursors to energy-rich or higher value-added products upon undergoing additional processing. In this study, batch reactors were utilized to assess the individual and interaction effects of fermentation time and pH variables on VFA production from acidogenic fermentation of cassava wastewater through the establishment of a completely randomized design and a second-order response surface (rotatable central composite design), respectively. The maximum VFA production observed was 3444.04 mg of acetic acid (HAc)/L (0.58 gCODVFA/gCOD) in a fermentation time of 6 days, with acetic (48.5%), propionic (28.3%), and butyric (13.6%) acids identified as the main metabolites. Additionally, in the assessment of the effect of pH, the maximum VFA production reached 2547.72 mgHAc/L (0.34 gCODVFA/gCOD) at pH 5.9, and acetic acid was identified as the predominant organic acid. Statistically, the fermentation time and pH variables individually affect VFA production from cassava wastewater; however, the interaction between them generated a non-significant effect.

Recycling of sludge residue as a coagulant for phosphorus removal from aqueous solutions.

Phosphorus pollution poses a significant challenge in addressing water contamination. The coagulant is one of the effective methods to remove phosphorus from wastewater. Abundant Al and Fe oxides in sludge residue make it have great potential to synthesize water treatment coagulants. However, the utilization of sludge residue for preparation of coagulant was seldom investigated. In this study, we fabricated a novel coagulant, polyaluminum ferric chloride (SM-PAC), using sludge residue as a raw material through acid leaching and polymerization processes. Characterization results confirm that the parameters of SM-PAC meet the specifications outlined in the national standard (GB/T 22627-2022). We investigated the effects of pH, dosage, initial phosphorus concentration, and contact time on the removal efficiency of SM-PAC. As anticipated, the prepared SM-PAC exhibited a significant efficacy in removing phosphorus, meeting the discharge standards set for municipal sewage. Furthermore, the adsorption kinetics analysis suggests that the predominant mode of phosphorus adsorption on SM-PAC is chemical adsorption. Furthermore, the SM-PAC was employed in the actual wastewater treatment plant and exhibited excellent efficiency in phosphorus removal. The utilization of SM-PAC can not only effectively address the issue of sludge disposal but also achieve the goal of "treating waste with waste." It is expected that the proposed method of reusing sludge residue as a resource can provide a sustainable way to synthesize a coagulant for phosphorus removal.

Adsorption of Pb, Cu, and Ni Ions on Activated Carbon Prepared from Oak Cupules: Kinetics and Thermodynamics Studies

Agricultural residue-activated carbon and biochar, inexpensive and environmentally friendly adsorbent materials, have recently received significant research attention. This study investigated the potential use of oak cupules in activated carbon form to remove widespread heavy metals (Pb2+, Cu2+, and Ni2+) from wastewater. The oak-activated carbon was prepared from oak cupules and activated with phosphoric acid. Oak-activated carbon was characterized using FTIR, BET analysis, energy-dispersive X-ray spectrometry (EDS), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The Freundlich, Langmuir, and Temkin isotherm models were used to assess the equilibrium data. The impact of various parameters, including pH effect, temperature, adsorbent dose, and contact time, was estimated. The Freundlich model was the most agreeable with Pb2+ adsorption by oak-based activated carbon, and Langmuir was more compatible with Cu+2 and Ni+2. Under optimum conditions, the average maximum removal was 63% Pb2+, 60% Cu2+, and 54% Ni2+ when every ion was alone in the aqueous solution. The removal was enhanced to 98% Pb2+, 72% Cu2+, and 60% Ni2+ when found as a mixture. The thermodynamic model revealed that the adsorption of ions by oak-based activated carbon is endothermic. The pseudo-second-order kinetic best describes the adsorption mechanism in this study; it verifies chemical sorption as the rate-limiting step in adsorption mechanisms. The oak-activated carbon was effective in removing Pb2+, Cu2+, and Ni2+ from wastewater and aqueous solutions.

A novel copper ion enhanced electrochemical DNA biosensor for the determination of epinephrine

A novel electrochemical biosensor was developed for the detection of epinephrine (EP) by immobilizing double-strand DNA (dsDNA) bound with copper ions on a gold electrode (Cu2+/dsDNA/MCH/AuE). The electrochemical behavior of EP at Cu2+/dsDNA/MCH/AuE was examined, and the results demonstrated a significant enhancement in the electrocatalytic oxidation peak current of EP due to the formation of a stable G-Cu(II)-G sandwich structure between Cu2+ and guanine at the modified electrode. The modification process of the electrode was characterized by scanning electron microscopy, infrared spectroscopy, electrochemical impedance spectroscopy, and differential pulse voltammetry. A study on the effect of pH in phosphate buffer solution on the electrochemical oxidation of EP indicated that the catalytic oxidation process was pH-dependent. A plot of catalytic current versus EP concentration exhibited a dual-linear relationship within two ranges: 1.0–12.5 μM and 12.5–1000.0 μM, with correlation coefficients of 0.995 and 0.997, respectively. The limit of detection was determined to be 47 nM (S/N = 3). According to the calculated Hill coefficient (0.99), it can be concluded that the electrocatalytic process followed the Michaelis-Menten kinetic mechanism. The maximum catalytic current Im was 25 μA, while the apparent Michaelis-Menten constant Km was 1.425 mM. These findings indicated excellent electrocatalytic activity of the modified electrode towards oxidation of EP. The developed biosensor successfully detected EP in spiked mouse serum as well as epinephrine hydrochloride injection with high selectivity, sensitivity, stability, and accuracy.

Sorption Behavior of Zirconium Ions from Aqueous Solutions Using Different Inorganic Sorbents Based on Titanate

AbstractIn this article, we explore the sorption behavior of Zr(IV) ions by lithium titanate (LiTi), magnesium titanate (MgTi), and lithium magnesium titanate (LiMgTi) sorbents. These sorbents, fabricated using the precipitation method, were used for the Zr(IV) sorption from aqueous solutions. We employed various analytical tools, including XRD, FT-IR, BET, SEM, and EDX, to examine the prepared sorbents’ structure, morphology, and functional groups. We also studied the effect of pH, time, initial metal concentrations, temperature, and interfering species on sorption. The kinetic data obey pseudo-first-order. Many isotherm models were utilised to investigate equilibrium data. The results of thermodynamic functions show an endothermic and spontaneous sorption process. Finally, the influence of the interfering species reveals that as the concentration of CaCl2, MgCl2, and NaCl increases, the Zr(IV) adsorption rate decreases. The investigation demonstrated that LiMgTi is suitable for retaining Zr(IV) from aqueous solutions and could purify effluent polluted with Zr(IV) ions.

Germination characteristics of Sorghum bicolor (L.) Moench. under different pH regimes after chemo-priming

AbstractSoil pH not only plays a regulatory role in seed germination but also influences seedling development, flowering, and crop yield. The study investigated the germination characteristics of sorghum [Sorghum bicolor (L.) Moench.] under varying pH to understand the potential ameliorative effects of seed priming using plant growth-promoting substances. Seeds were sown in Petri dishes with pH moistened solutions at 1, 3, 5, 7, 9, 11, and 13 respectively. These were replicated five times in the second stage, viable seeds were first primed in 150 ppm indole-3-acetic acid, gibberellic acid, and vitamin C before sowing in pH solutions. The experiment showed no significant changes in morphology or physiology of primed and unprimed seeds and no germination at extreme pH. However, there was a significant difference in the activity of enzymes, germination time, and speed as well as germination percentages of both primed and unprimed seeds. Although chemo-priming did not reverse the effect of pH, it was observed however that vitamin C had a significant effect on germination percentage at higher pH. Germination was observed to be impaired at extreme pH. Seeds did not respond to germination capacity suggesting an optimal pH range of 3 and 11 for germination without priming. However, priming did not show any improved germinability index. Seeds primed in the presence of light showed enhanced germination at pH 7. Generally, the germination index without priming showed better germination characteristics than primed seeds, which suggests pH interactions with primers may be a limiting factor.

Effect of pH on the thermostability and redox properties of cytochrome c552 from Wolinella succinogenes

Effect of pH on the thermostability and redox properties of cytochrome c552 from Wolinella succinogenes

Efficient removal of heavy metal ions by modified cellulose prepared from rice husk: Equilibrium isotherms, Kinetics and desorption studies

The cellulose acetate was prepared from the naturally occurring cellulose extracted from rice husk. It was then characterized using FTIR, XRD, SEM/EDS, TEM and BET and the results were connected to their potential applications in the elimination of heavy metal ions. Differential pulse voltammetry was used for quantitative study of heavy metal ions. An adsorption experiment was conducted to study the effect of temperature, initial concentration, adsorbent dosage, pH and contact time on the adsorption capacity of cellulose acetate. The results of the adsorption experiment showed that the removal of metal ions from adsorbent was a pH-dependent, reaching its maximum adsorption capability at pH of 5-6. Adsorption process was effective with adsorbent dosage was 10±0.1 mg/mL and the temperature was kept at 303K. The adsorption properties of cellulose acetate can be effectively described by pseudo-second-order kinetic with lower error function value and adsorption isotherm such as Freundlich and Temkin adsorption model at 50 min contact time and 50±0.1 mg/L initial concentration. The thermodynamic parameters were investigated, they shows adsorption is favorable at low temperatures. Desorption and re-adsorption of the heavy metals were also studied. Cellulose acetate still retains its adsorption efficiency up to 6th cycles of adsorption.

When covalent organic frameworks meet zeolites: Enhancing rhodamine B removal through the synergy in the emerging organic–inorganic nanoadsorbents

The development of new porous materials has attracted intense attention as adsorbents for removing pollutants from wastewater. However, pure inorganic and organic porous materials confront various problems in purifying the wastewater. In this work, we integrated a covalent organic framework (TpPa-1) with an inorganic zeolite (TS-1) for the first time via a solvothermal method to fabricate new-type nanoadsorbents. The covalent organic framework/zeolite (TpPa-1/TS-1) nanoadsorbents combined the merits of the zeolite and COF components and possessed efficient adsorptive removal of organic contaminants from solution. Structural morphology and chemical composition characterization by powder X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy and thermogravimetric analysis demonstrated the successful preparation of TpPa-1/TS-1 composite nanoadsorbents. The resultant composite adsorbent TpPa-1/TS-1 removed rhodamine B at 1.7 and 2.6 times the efficiency of TpPa-1 and TS-1, respectively. Additional investigation revealed that the Freundlich adsorption isotherm and the pseudo-second-order kinetic model could be employed to represent the adsorption process more appropriately. Thermodynamic calculation analysis showed that the adsorption process proceeded spontaneously and exothermically. Besides, the effects of pH, absorbent mass and ionic strength on the adsorption performance were systematically investigated. The prepared composite adsorbent showed a slight decrease in removal efficiency after eight cycles of repeated use, and real water environment experiments also showed the high stability of the adsorbent. The enhanced performance can be attributed to electrostatic interaction, acid-base interaction, hydrogen bonding and π–π interactions.

Effects of pH on interactions between rice and pea grown under hydroponic condition

Effects of pH on interactions between rice and pea grown under hydroponic condition

Effect of pH on the emulsifying performance of protein-polysaccharide complexes.

Protein-polysaccharide complexes have been successfully used for emulsion stabilization. However, it is unclear how the complex's surface charge influences aggregation stability and coalescence stability of emulsions, and whether a low charged interfacial film can still maintain the coalescence stability of oil droplets. In the present study, the effects of pH (around the pI of protein) on the aggregation and coalescence stability of emulsions were investigated. Whey protein isolate (WPI) and peach gum polysaccharides (PGP) complexes (WPI-PGP complexes) were synthesized at pH 3, 4 and 5. Their sizes were 598, 274 and 183 nm, respectively, and their ζ-potentials were +2.9, -8.6 and -22.8 mV, respectively. Interface rheological experiments showed that WPI-PGP complex at pH 3 had the lowest interfacial tension, and formed the softest film compared to the complexes at pH 4 and 5. Microfluidic experiments showed that all WPI-PGP complexes were able to stabilize droplets against coalescence within short timescales (milliseconds). At pH 3, no coalescence was observed even under conditions where the continuous phase flow influenced the shape of oil droplets (from spheres to ellipsoids). At pH 4 and 5, the model emulsions were stable over 16 days of storage, extensive aggregation and creaming occurred at pH 3 after 8 days. Importantly, no coalescence took place. The present study confirmed that the aggregation stability of the emulsions was mainly determined by the surface charge of the complex, whereas the coalescence stability of emulsions is expectedly determined by steric repulsion, providing new insights into how to prepare stable food emulsions. © 2024 Society of Chemical Industry.

Management of caffeine in wastewater using MOF and perovskite materials: optimization, kinetics, and adsorption isotherm modelling

AbstractPharmaceuticals and personal care products (PPCPs) have been increasingly used all over the world and they have been reported on water cycle and cause contamination. Among these pharmaceuticals is caffeine (CAF). In this work, CAF removal from aqueous samples by metal–organic framework (UIO-66) and perovskite (La0.7Sr0.3FeO3) was achieved. Detailed studies on the preparation of MOFs and perovskite oxides compounds have been presented. Extensive characterizations such as X-Ray diffraction (XRD), field emission scanning electron microscope (FESEM), Fourier transform infrared spectra (FT-IR), N2 adsorption–desorption isotherms were also carried out to assure proper formation and to better understand the physico-chemical behavior of the synthesized samples before and after adsorption. Batch experiments of CAF adsorption onto both MOFs and perovskite were performed to compare the effectiveness of both materials on the removal competence of the CAF residue at different conditions including the effect of pH, initial concentration, and contact time. It was observed that the adsorption capacity of CAF by MOF increased with increasing acidity. On the other hand, the adsorption capacity of perovskite is stable in pH 4–10. The maximum adsorption capacities of UiO-66 and perovskite toward CAF are high as 62.5 mg g−1 and 35.25 mg g−1, respectively. Equilibrium isotherms were investigated by numerous models: Langmuir, Freundlich, Temkin, Redlich-Peterson, Sips, Langmuir-Freundlich, Toth, Kahn, Baudu, and Fritz Schlunder. Moreover, the kinetics of the CAF@MOF and CAF@Perovskite systems have been studied by five kinetic models (Pseudo-1st -order (PFO), Pseudo-2nd -order (PSO), Mixed 1st, 2nd-order, Intraparticle diffusion and Avrami). The best model described the adsorption of CAF onto both of MOF and perovskite was the mixed 1st, 2nd-order model. The metal–organic framework and perovskite were applied to quickly extract CAF from water samples successfully. The maximum removal percentage obtained for MOF and perovskite was 0.89% and 0.94% respectively within 30 min contact time which suggests that these materials are considered as promising adsorbents for CAF.

An Incubation System for the Simulation of Ammonia Emissions from Soil Surface-Applied Slurry: Effect of pH and Acid Type

Acidification of slurry is a promising approach for reducing ammonia emissions during the application procedure. Since only a few studies have been conducted focusing on ammonia emissions during the application of liquid organic fertilizers on the soil surface, a suitable incubation system was developed to evaluate the effects of acidification under controlled conditions. This incubation system was used to measure the ammonia emissions of various liquid organic fertilizers. The substrates were acidified with sulfuric and citric acid to different pH values to determine both the influence of the pH value of the substrates and of the type of acid on the ammonia emissions. The emissions decreased with declining pH value, and the reduction in emissions compared to the initial pH of the substrate was over 86% for pH 6.5 and over 98% for pH 6.0 and below. At the same pH value, the ammonia emissions did not differ between substrates acidified with citric acid and sulfuric acid, although more than twice as much 50% citric acid was required compared to 96% sulfuric acid to achieve the same pH value. Overall, our results demonstrate that the incubation system used is suitable for measuring ammonia emissions from surface-applied liquid organic fertilizers. The system allows for the differentiation of emission levels at various pH levels and is therefore suitable for testing the effectiveness of additives for reducing ammonia emissions from liquid organic fertilizers.

Synthesis and characterisation of hydrogel based on propiolic acid

ABSTRACT In this study, using a propiolic acid monomer and ammonium persulphate as initiator and N,N’-methylenebisacrylamide as crosslink agent, poly propiolic acid hydrogel was designed and tested for water absorption. Also, to investigate the effect of pH on hydrogel’s efficiency, swelling was investigated at different pH levels. To obtain the optimal formula for hydrogel with maximum water absorption, the initiator and crosslink agent levels were changed. The obtained data showed that the highest conversion rate of monomer to polymer was observed for the S1 sample with an initiator concentration of 10% by weight and a crosslinking agent with a concentration of 2% by weight. It also has the highest water absorption for this sample and its swelling rate is 27.6 times that of dry hydrogel. Increasing the concentration of the crosslinking agent and reducing the amount of initiator resulted in the reduction of hydrogel swelling in water. Also, the swelling rate of samples at different pH shows that reducing pH to acidic environments or increasing it to basic environments led to a decrease in network swelling in all three samples. Finally, to investigate the structure and morphology of hydrogels, FTIR, SEM, and measuring the amount of hydrogel swelling at ambient temperature tests were used.

Extraction, Physicochemical Properties, and In Vitro Antioxidant Activities of Chondroitin Sulfate from Bovine Nose Cartilage.

Beef is an important high-nutrition livestock product, and several byproducts, such as bovine cartilage, are produced during slaughter. To effectively utilize these agricultural and pastoral byproducts, combined (trypsin-papain) enzymolysis and cetylpyridine chloride purification methods were used to obtain chondroitin sulfate (CS) from the nasal cartilage of Shaanxi Yellow cattle. The effects of pH, temperature, and time on the CS yield during enzymatic hydrolysis were investigated, and the CS extraction process was optimized using response surface methodology. The best yield of CS was 21.62% under the optimum conditions of pH 6.51, temperature of 64.53°C, and enzymolysis time of 19.86 h. The molecular weight of CS from Shaanxi cattle nasal cartilage was 89.21 kDa, glucuronic acid content was 31.76 ± 0.72%, protein content was 1.12 ± 0.03%, and sulfate group content was 23.34 ± 0.08%. The nasal cartilage CS of the Yellow cattle showed strong DPPH•, •OH, and ABTS+• radical scavenging abilities and ferrous reduction ability in the experimental concentration range. This study could contribute to "turn waste into treasure" and improve the comprehensive utilization of regional characteristic biological resources.