Acid and Alkali Buffer Capacity of Typical Fluvor-Aquic Soil in Huang-Huai-Hai Plain

Soil acid and alkali buffer capacity, as a major indicator for evaluating its vulnerability and resistibility to acidification and alkalization, is an important factor affecting the sustainable agriculture, through knowledge on which soil acidification process can be predicted and modified. In this study, titration curve method was adopted to investigate the pH buffer capacity （pHBC） of fluvor-aquic soil, and separate titration curves were established by adding incremental amounts of either standardized hydrochloric acid （HC1） （0.12 mol L^-1） or sodium hydroxide （NaOH） （0.10 mol L^-1） to soil suspended in deionized water （soil：solution = 1：5）. Soil pH was measured after 7 d resuspension and isothermal equilibrium （T = 25℃）. Linear regressions were fitted to the linear portion of each titration curve and the slopes of these lines were derived as the soil pHBC. The results showed that significant correlations between the amounts of adding acid or alkali and each pH change were presented, and titration curve method was feasible for measurement of pHBC on typical fluvor-aquic soil in Huang-Huai-Hai Plain, and the coefficients of determination were higher than the similar researches on acid soil （R^2 = 0.96）. The slope-derived pHBC of acid and alkali were 158.71 and 25.02 mmol kg^-1, respectively. According to the classification of soil buffer systems, the soil tested belongs to the calcium carbonate buffer system, carbonates contribute the most to pHBC, and the contribution of soil organic matter relatively less than it.

Buffer capacity of granular matter to impact of spherical projectile based on discrete element method

Granular matter possesses impact-absorbing property due to its energy dissipation character.To investigate the impact-absorbing capacity of granular matter,the discrete element method(DEM)is adopted to simulate the impact of a spherical projectile on to a granular bed.The dynamic responses of the projectile are obtained for both thin and thick granular bed.The penetration depth of the projectile and the first impact peak are investigated with different bed thicknesses and impact velocities.Determining a suitable bed thickness is crucial to the buffering effect of granular matter.The first impact peak is independent of bed thickness when the thickness is larger than the critical thickness.

Solid components and acid buffering capacity of soils in South China

The effects of soil solid components on soil sensitivity to acid deposition by sequential extraction method were studied. A multiple regression equation of soil sensitivity was set up on the basis of stepwise regression analysis. The results showed that organic matter expressed dual effects that were decided by soil original pH value and exchangeable cation composition on acid buffering reactions. The hydrolysis of activated oxides was a very important proton buffering reaction when in low pH situation. The crystalline oxides also played a role in the buffering reactions, but the role was restricted by the rate of activation of oxides. Meanwhile, the results by stepwise analysis showed that factors that had significant effect on soil acid buffering capacity were content of montmorillite, soil original pH value, Al 0, Mn 0 and CEC in decreasing order. Finally, sixteen soils were classified into four types of sensitive with single index cluster and multiple fuzzy cluster analysis respectively.

Linear Regression Relationship between Lychee Juice Content and Buffering Capacity

Juice drinks are an important commercialization alternative for lychee, a tropical and subtropical fruit. Although the lychee juice content is important when assessing the quality of a drink, there are no published methods to determine it, particularly simple ones for the routine inspection of juice drinks. Lychee juice drinks contain ingredients with buffering capacity including proteins and ions such as phosphate, citrate, lactate, carbonate, acetate and propionate. The relationship between their buffering capacity and lychee juice content was studied. Citric acid was added to pure lychee dilutions in distilled water containing 100%, 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20% and 10% lychee juice. The pH of the dilutions was measured to obtain a linear model for the molar H+ concentration as a function of the added citric acid (g/L) amount LC = (BC-494.2)/12,031, where LC was the lychee juice content and BC was defined as the juice buffering coefficient.

Calcium-based polymers for suppression of soil acidification by improving acid-buffering capacity and inhibiting nitrification

Soil acidification is a major threat to agricultural sustainability in tropical and subtropical regions.Biodegradable and environmentally friendly materials,such as calcium lignosulfonate(CaLS),calcium poly(aspartic acid)(PASP-Ca),and calcium polyγ-glutamic acid(γ-PGA-Ca),are known to effectively ameliorate soil acidity.However,their effectiveness in inhibiting soil acidification has not been studied.This study aimed to evaluate the effect of CaLS,PASP-Ca,andγ-PGA-Ca on the resistance of soil toward acidification as directly and indirectly(i.e.,via nitrification)caused by the application of HNO_(3)and urea,respectively.For comparison,Ca(OH)_(2)and lignin were used as the inorganic and organic controls,respectively.Among the materials,γ-PGA-Ca drove the substantial improvements in the pH buffering capacity(pHBC)of the soil and exhibited the greatest potential in inhibiting HNO_(3)-induced soil acidification via protonation of carboxyl,complexing with Al~(3+),and cation exchange processes.Under acidification induced by urea,CaLS was the optimal one in inhibiting acidification and increasing exchangeable acidity during incubation.Furthermore,the sharp reduction in the population sizes of ammonia-oxidizing bacteria(AOB)and ammonia-oxidizing archaea(AOA)confirmed the inhibition of nitrification via CaLS application.Therefore,compared to improving soil pHBC,CaLS may play a more important role in suppressing indirect acidification.Overall,γ-PGA-Ca was superior to PASP-Ca and CaLS in enhancing the soil pHBC and the its resistance to acidification induced by HNO_(3) addition,whereas CaLS was the best at suppressing urea-driven soil acidification by inhibiting nitrification.In conclusion,these results provide a reference for inhibiting soil re-acidification in intensive agricultural systems.

Acidification of the Skin and Maintenance of the Physiological Skin pH Value by Buffered Skin Care Products Formulated around pH 4

Each biological system possesses a widely unrecognized buffer system to maintain acid-base balance to a specific pH. The skin pH is crucial for physiological skin function. In aged or diseased skin, pH increase is observed and may negatively affect skin health. Skin care products with a pH that is slightly more acidic than the average normal skin pH and have an adequate buffering capacity, are considered beneficial for the skin. However, the buffer capacity of these products also plays an important role. In the present study, a possible normalization or acidification of skin surface pH and influence on skin hydration and skin barrier function was assessed via application of buffered skin care products that are formulated with pH ≤ 4.5. 48 subjects aged above 50 were treated with three different skin care products (Vitamin C Spheres, Collagen Spray, and Collagen Mask) and skin surface pH, skin hydration and barrier integrity were assessed before treatment start and after 4 weeks. The results show that after 4-week treatment with Vitamin C, the skin pH is acidified. Treatment with Collagen Spray and Collagen Mask showed maintenance of a physiological skin pH. Subgroup analysis of subjects that had a higher than average skin pH at study start demonstrated that all three tested skin care products were able to acidify the skin surface. In addition, skin hydration was also increased for two of the three tested products, whereas skin barrier is not significantly changed. This demonstrates that buffered skin care products formulated to a pH ≤ 4.5 are able to acidify and maintain physiological skin pH and may contribute to a physiological skin function.

Effects of alkaline ameliorator additions on the acidic buffering abilities of aluminum－rich alfisols

Lime and coal flying ash applications could mitigate pollution from acid deposition and improve the buffering ability of two acidic soils sampled from Zhejiang Province. The results showed that soil alkalinity and acidified buffering capacities (QpHs ) were significantly increased, especially for liming treatment; whereas, the amounts of SO24- adsorbed by treated soils were decreased to some degrees because net negative charges of soil oxide colloidal surfaces were increased with the decrease in soil acidity, although the soil fixation abilities for adsorbed SO24- were not reduced. These facts indicated that after the alkaline ameliorators were applied, the positive and adverse effects resulted from sulfate-type acid deposition were simultaneously existed in these soil treatments.

The Cation Exchange Capacity of Fibrous Feedstuff and Its Nutritive Characteristics

Current researches on the nutritive characteristics of fibrous feedstuff through determining the feedstuff cation exchange capacity (CEC) to evaluate its nutritive value at home and abroad were comprehensively discribed. and the methods of determining CEC value and the correlation between CEC value and chemical compositions, pH value, and the effect of CEC value on the digestion kinetics in ruminants were also emphatically introduced. The results of research showed that the CEC values of different feedstuff are different, closely correlated with nitrogen and acid detergent fibre (ADF) and lignin (LIG) content of the feedstuff. At the same time, there are markedly effect of CEC value in diet on the nutrients flow of digesta in the digestive tract of ruminants, the degradation rate and digestibility of nutrients in the rumen.

Role of Resuspended Sediments as Sources of Dissolved Inorganic Phosphorus Along Different Dimensions in the Subei Shoal, South Yellow Sea, China

Several studies have documented that during‘green tide’events,comprising green macroalgae blooms in aquatic ecosystems,dissolved inorganic phosphorus(DIP)levels remain relatively steady despite the absorption of a large amount of DIP.In this study,surface sediment samples and a sediment core were extracted using a modified sequential extraction scheme,and water and surface sediment samples were analyzed in April 2017 to better understand phosphorus(P)cycling and replenishment in Subei shoal.We used a simple model on equilibrium of adsorption-desorption to present the buffering capacity of phosphate.The total P(TP)in the surface sediments ranged from 12.2 to 28.4μmol g^(-1)(average 15.5μmol g^(-1))and was dominated by inorganic P.TP,exchangeable P,reactive and reductive Fe/Al bound P,and authigenic apatite P significantly decreased northward and eastward from Subei shoal,contrary to the detrital P and organic P results.Dissolved and particulate inorganic P in the water samples ranged from 0.01 to 0.54μmol L^(-1)(average 0.19μmol L^(-1))and 0.9 to 19.6μmol g^(-1)(average 4.9μmol g^(-1)),respectively.The applied model showed that suspended particulate matter is an important regulator of DIP behavior.Thus,modification of SPM can alter the DIP buffering capacity.The calculated buffering capacity in the surface layer of the sea water was>60 within Subei shoal and always>10 along the path of floating Ulva prolifera,providing a reasonable explanation for the steady concentration of DIP and its replenishment during the blooming of this green macroalgae.

Quaternary Oxide of Cerium, Terbium, Praseodymium and Zirconium for Three-Way Catalysts

Oxygen storage-capacity （OSC）, oxygen buffer capacity （OBC）, X-my diffraction and electron diffraction pattern, high resolution electron microscopy were used to study the quaternary oxides, i .e., of Ce, Tb, Pr and Zr. （Ce0.6 Tb0.2Zr0.2O2- δ and Ce0.6Pr0.2Zr0.2O2-δ ）. OSC and OBC data indicate that these oxides have very good oxygen transfer capacity （OTC） and their pseudo-solid solutions exhibit fluorite-type structure. These oxides may act as a good candidate for three-way catalysts （TWC）.

Proton accumulation accelerated by heavy chemical nitrogen fertilization and its long-term impact on acidifying rate in a typical arable soil in the Huang-Huai-Hai Plain

Cropland productivity has been significantly impacted by soil acidification resulted from nitrogen （N） fertilization, especially as a result of excess ammoniacal N input. With decades＇ intensive agricultural cultivation and heavy chemical N input in the Huang-Huai-Hai Plain, the impact extent of induced proton input on soil pH in the long term was not yet clear. In this study, acidification rates of different soil layers in the soil profile （0-120 cm） were calculated by pH buffer capacity （pHBC） and net input of protons due to chemical N incorporation. Topsoil （0-20 cm） pH changes of a long-term fertilization field （from 1989） were determined to validate the predicted values. The results showed that the acid and alkali buffer capacities varied significantly in the soil profile, averaged 692 and 39.8 mmolc kg-1 pH-1, respectively. A significant （P〈0.05） correlation was found between pHRC and the content of calcium carbonate. Based on the commonly used application rate of urea （500 kg N ha-1 yr-1）, the induced proton input in this region was predicted to be 16.1 kmol ha-1 yr-1, and nitrification and plant uptake of nitrate were the most important mechanisms for proton producing and consuming, respectively. The acidification rate of topsoil （0-20 cm） was estimated to be 0.01 unit pH yr-1 at the assumed N fertilization level. From 1989 to 2009, topsoil pH （0-20 cm） of the long-term fertilization field decreased from 8.65 to 8.50 for the PK （phosphorus, 150 kg P205 ha-1 yr-1; potassium, 300 kg K20 ha-1 yr-1; without N fertilization）, and 8.30 for NPK （nitrogen, 300 kg N ha-1 yr-1; phosphorus, 150 kg P2Os ha-1 yr-1; potassium, 300 kg K20 ha -1 yr-1）, respectively. Therefore, the apparent soil acidification rate induced by N fertilization equaled to 0.01 unit pH yr-1, which can be a reference to the estimated result, considering the effect of atmospheric N deposition, crop biomass, field management and plant uptake of other nutrients and cations. As protons could be consumed by some field practices, such as stubble return and coupled water and nutrient management, soil pH would maintain relatively stable if proper management practices can be adopted in this region.

Sheep manure application increases soil exchangeable base cations in a semi-arid steppe of Inner Mongolia

The long-term productivity of a soil is greatly influenced by cation exchange capacity（CEC）.Moreover,interactions between dominant base cations and other nutrients are important for the health and stability of grassland ecosystems.Soil exchangeable base cations and cation ratios were examined in a 11-year experiment with sheep manure application rates 0–1,500 g/（m2？a） in a semi-arid steppe in Inner Mongolia of China,aiming to clarify the relationships of base cations with soil p H,buffer capacity and fertility.Results showed that CEC and contents of exchangeable calcium（Ca2＋）,magnesium（Mg2＋）,potassium（K＋） and sodium（Na＋） were significantly increased,and Ca2＋ saturation tended to decrease,while K＋ saturation tended to increase with the increases of sheep manure application rates.The Ca2＋/Mg2＋ and Ca2＋/K＋ ratios decreased,while Mg2＋,K＋ and Na＋ saturations increased with increasing manure application rates.Both base cations and CEC were significantly and positively correlated with soil organic carbon（SOC） and soil p H.The increases of SOC and soil p H would be the dominant factors that contribute to the increase of cations in soil.On a comparison with the initial soil p H before the experiment,we deduced that sheep manure application could partly buffer soil p H decrease potentially induced by atmospheric deposition of nitrogen and sulfur.Our results indicate that sheep manure application is beneficial to the maintenance of base cations and the buffering of soil acidification,and therefore can improve soil fertility in the semi-arid steppes of northeastern China.

Sensitivity of soils to acid rain in South China

This paper deals with the sensitivity of soils to acid rain in 5 provinces, South China. Based on field work and literature, and taking soil pH, CEC, and the types of residua into account, the authors classified the sensitivity into 4 categories: highly sensitive, sensitive, slightly sensitive, and non-sensitive. By overlapping the maps of soil pH, CEC, and types of residua, the map of soil sensitivity in South China has finally resulted.The authors try to summarize the regularity of soil sensitivity to acid rain in this area. The sensitivity of different soil types in the studied area has also discussed.The seriousness and its prospects of acid rain in this area have been pointed out in order to draw the attention of relevant authorities.

Comparison of Acidity Parameters for Soils under Perennial and Annual Pastures in Victoria

There are about 5 million ha of strongly acid soils (pH < 4.8 in 0.01 mol·L -1 CaCl 2 ) in Victoria and about 11 million ha of mildly acid soils (pH 4.8～5.5) that are considered susceptible to further acidification under current agricultural use. However, there appear to be differences in the rate of acidification, as measured by soil pH change, between soils under perennial pastures in the higher rainfall areas of southern Victoria and soils under annual pastures in the sheep-wheat areas of the north-east. Measurements made on representative soils from both regions showed that the southern soils generally had a higher pH buffer capacity, which was primarily determined by the organic carbon content. There was a consistent relationship between the short-term buffer capacity (measured by titration) and the long-term buffer capacity (measured by incubation), irrespective of the origin of the soils. Exchangeable Al, measured in 0.01 mol·L -1 CaCl 2 , was strongly negatively correlated with pH and the relationship for all soils suggested that Al was adsorbed as a cation with an average charge of 1.2

Intraspecific Variations of Phosphorus Absorption and Remobilization, P Forms, and Their Internal Buffering in Brassica Cultivars Exposed to a P-Stressed Environment

Translocation of absorbed phosphorus （P） from metabolically inactive sites to active sites in plants growing under P deprivation may increase its P utilization efficiency （PUE）. Acclimation to phosphate （Pi） starvation may be caused by a differential storage pool of vacuolar P, its release, and the intensity of re-translocation of absorbed P as P starvation inducible environmental cues （PSlEC） from ambient environment. Biomass assay and three P forms, namely inorganic （Pi）, organic （Po）, and acid-soluble total （Ptas） were estimated in Brassica cultivars exposed to 10 d P deprivation in the culture media. Considering that -aPi/at denotes the rate of Pi release, Pi release velocity （RSPi） was determined as the tangent to the equations obtained for Pi f（t） at the mean point in the period of greatest Pi decrease, whereas the inverse of the RSPi was an estimate of the internal Pi buffering capacity （IBCPi）. Inter cultivar variations in size of the non-metabolic Pi pool, RSPi, re-translocation of Pi from less to more active metabolic sites, and preferential Pi source and sink compartments were evaluated under P starvation. The cultivar ＇Brown Raya＇ showed the highest Pi storage ability under adequate external P supply, and a more intensive release than ＇Rain Bow＇ and ＇Dunkled＇ under P stress. Cultivar ＇B.S.A＇ was inferior to ＇Con-l＇ in its ability to store and use Pi. Roots and upper leaves were the main sink of Pi stored in the lower and middle leaves of all cultivars and showed lower IBCPi and larger RSPi values than lower and middle leaves. In another trial, six cultivars were exposed to P-free nutrition for 29 d after initial feeding on optimum nutrition for 15 d. With variable magnitude, all of the cultivars re-translocatad P from the above ground parts to their roots under P starvation, and [P] at 44 d after transplanting was higher in developing leaves compared with developed leaves. Under P deprivation, translocation of absorbed P from metabolically inactive to active sites may have helped the tolerant cultivars to establish a better rooting system, which provided a basis for tolerance against P starvation and increased PUE. A better understanding of the extent to which changes in the flux of P absorption and re-translocation under PSIEC will help to scavenge Pi from bound P reserves and will bring more sparingly soluble P into cropping systems and obtain capitalization of P reserves.

Synthesis of Water-soluble, Polyester-based Dendrimer Prodrugs for Exploiting Therapeutic Properties of Two Triterpenoid Acids

Dendrimers are macromolecules characterized by high controlled size, shape and architecture, presence of inner cavities able to accommodate small molecules and many peripheral functional groups to bind target entities. They are of eminent interest for biomedical applications, including gene transfection, tissue engineering, imaging, and drug delivery. The well-known pharmacological activities of ursolic and oleanolic acids are limited by their small water solubility, non-specific cell distribution, low bioavailability, poor pharmacokinetics, and their direct administration could result in the release of thrombi. To overcome such problems, in this paper we described their physical incorporation inside amino acids-modified polyester-based dendrimers which made them highly water-soluble. IR, NMR, zeta potential, mean size of particles, buffer capacity and drug release profiles of prepared materials were reported. The achieved water-soluble complexes harmonize a polycationic character and a buffer capacity which presuppose efficient cell penetration and increased residence time with a biodegradable cell respectful scaffold, thus appearing as a promising team of not toxic prodrugs for safe administration of ursolic and oleanolic acids.