Low Concentrations Of Acetic Acid Research Articles

Compound lactic acid bacteria enhance the aerobic stability of Sesbania cannabina and corn mixed silage

BackgroundThe strategic delay of aerobic deterioration in Sesbania cannabina and corn (SC) mixed silage, coupled with effective fermentation, could increase the protein-rich silage utilization by ruminants. Thus, we sought to investigate the role of a compound lactic acid bacteria (LAB) inoculant (Lactobacillus plantarum + Lactobacillus farciminis + Lactobacillus buchneri + Lactobacillus hilgardii; at a level of 106 CFU/g fresh weight) in enhancing the aerobic stability of SC mixed silage. Specifically, we focused on the potential for corn supplementation to improve fermentation quality while concurrently increasing the susceptibility of SC mixed silage to aerobic spoilage.ResultsResults revealed that compound LAB additive diversified the microbial community of SC mixed silage, making Lactobacillus hilgardii and Lactobacillus buchneri dominant bacterial species, while decreasing the abundance of Kazachstania humilis fungal specie. As a result, the LAB-treated mixed silages had higher acetic acid contents and lower yeast populations. Aerobic stability analysis revealed that the SC mixed silages with a high corn proportion deteriorated rapidly when the silages were exposed to air. The high aerobic stability of the LAB-treated mixed silages especially S7C3 contrasted with the low acetic acid concentrations in the CK mixed silages (processed with sterilized water), concomitant with increased Kazachstania humilis abundance.ConclusionOur study revealed that inoculation with a compound LAB additive altered the consequences of aerobic exposure by increasing acetic acid production after ensiling, promoting diverse bacterial populations, and mitigating the negative effects of fungi on the aerobic stability of SC mixed silage.

The Impact of the Inoculation of Different Pied de Cuve on the Chemical and Organoleptic Profiles of Wines.

Controlling the microorganisms involved in alcoholic fermentation during wine production can be achieved by adding a small quantity of spontaneously fermenting must to freshly crushed grapes, a technique known as pied de cuve (PdC). This method not only serves as an inoculation starter but also enhances the microbial footprint unique to each wine region. Recent studies have confirmed that wines inoculated with PdC exhibit efficient fermentation kinetics comparable to those inoculated with commercial strains of Saccharomyces cerevisiae. However, further research is required to draw robust conclusions about the chemical and sensory impacts of PdC-inoculated wines. In this study, we examined the chemical and sensory effects of the PdC technique across three different harvests: Muscat of Alexandria (Spain, harvests 2022 and 2023) and Sauvignon Blanc (Chile, harvest 2023). Each PdC was prepared using various stressors (sulfur dioxide, ethanol, and temperature). Our findings revealed that wines produced with PdC exhibited similar fermentation kinetics and sensory profiles to those inoculated with commercial strains. Notably, PdC fermentations resulted in lower concentrations of acetic acid compared to both the commercial strain and spontaneous fermentations. The sensory analysis indicated that PdC wines significantly differed from those made with commercial strains, with PdC wines displaying more pronounced tropical notes. These results suggest that the PdC technique, particularly when using specific stressors, can maintain desirable fermentation characteristics while enhancing certain sensory attributes, offering a viable alternative to traditional inoculation methods.

Valorization of Corn Straw for Production of Glucose by Two-Step Depolymerization.

Depolymerization of the cellulose part in lignocellulose to glucose is a significant step for lignocellulose valorization. As one of the main by-products of agricultural biomass in crop-producing filed, valorization of corn straw has attracted considerable attention. In this study, a two-step depolymerizing strategy of high-pressure CO2-H2O pretreatment and oxidation-hydrolysis was applied for selective depolymerization of the cellulose component of corn straw to glucose production. Most part of the hemicellulose component could be removed through high-pressure CO2-H2O pretreatment in the presence of low concentration of acetic acid, and then as high as 32.2 % yield of glucose was achieved in water at 170 °C for 6 h without additional catalyst. The active acid sites generated during the partial oxidation of hydroxymethyl groups to carboxyl groups on glucose units of cellulose was shown to be crucial for the efficient valorization of corn straw for glucose production.

Isolation, Identification, and Characterization of an Acid-Tolerant Pichia kudriavzevii and Exploration of Its Acetic Acid Tolerance Mechanism

Pichia kudriavzevii is one of the major non-Saccharomyces cerevisiae yeasts in Chinese baijiu brewing, which has shown a substantially higher tolerance to acid, heat, and ethanol. Exploring the mechanism of P. kudriavzevii could have a positive effect on the artificially controlled production of baijiu. In this study, an efficient acetic-acid-tolerant P. kudriavzevii strain, Y2, was isolated from the yellow water of strong-flavored baijiu brewing waste, and its molecular mechanism of acetic acid tolerance was investigated through a comparative transcriptomic analysis. The strain Y2 could tolerate 12 g/L of acetic acid. According to the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, differentially expressed genes (DEGs) were mainly enriched in oxidative phosphorylation, the citrate cycle, glycolysis/gluconeogenesis, and carbon metabolism under low (AL group) and high (AH group) concentrations of acetic acid. However, the DEG enrichment was more profound in the AH group when compared to the control. Compared with the AL group, the expression of genes related to oxidative phosphorylation was more significantly upregulated, while in terms of the TCA cycle, phosphoenolpyruvate carboxykinase was significantly upregulated in both the AH and AL groups and was positively correlated with tolerance to acetic acid. This was followed by citrate synthase, isocitrate dehydrogenase, malate dehydrogenase, and succinate dehydrogenase. These results illustrated a possible mechanism of acid tolerance by regulating the metabolism-related pathways in P. kudriavzevii and provided a basis for the further investigation of the acid tolerance mechanism.

Biological Safety Assessments of High-Purified Ovine Collagen Type I Biomatrix for Future Therapeutic Product: International Organisation for Standardisation (ISO) and Good Laboratory Practice (GLP) Settings.

Wound care management is incredibly challenging for chronic injuries, despite the availability of various types of wound care products in the market. However, most current wound-healing products do not attempt to mimic the extracellular matrix (ECM) and simply provide a barrier function or wound covering. Collagen is a natural polymer that involves a major constituent of the ECM protein, thus making it attractive to be used in skin tissue regeneration during wound healing. This study aimed to validate the biological safety assessments of ovine tendon collagen type-I (OTC-I) in the accredited laboratory under ISO and GLP settings. It is important to ensure that the biomatrix will not stimulate the immune system to produce any adverse reaction. Therefore, we successfully extracted collagen type-I from the ovine tendon (OTC- I) using a method of low-concentration acetic acid. The three-dimensional (3D) skin patch of spongy OTC-I was a soft and white colour, being tested for safety and biocompatibility evaluations based on ISO 10993-5, ISO 10993-10, ISO 10993-11, ISO 10993-23, USP 40 <151>, and OECD 471. For the dermal sensitisation and acute irritation test, none of the tested animals displayed any erythema or oedema effects (p > 0.005). In addition, there were no abnormalities detected in the organ of the mice after being exposed to OTC-I; additionally, no morbidity and mortality were observed in the acute systemic test under the guideline of ISO 10993-11:2017. The grade 0 (non-reactive) based on ISO 10993-5:2009 was graded for the OTC-I at 100% concentration and the mean number of the revertant colonies did not exceed 2-fold of the 0.9% w/v sodium chloride compared to the tester strains of S. typhimurium (TA100, TA1535, TA98, TA1537), and E. coli (WP2 trp uvrA). Our study revealed that OTC-I biomatrix does not present any adverse effects or abnormalities in the present study's condition of induced skin sensitization effect, mutagenic and cytotoxic towards cells and animals. This biocompatibility assessment demonstrated a good agreement between in vitro and in vivo results regarding the absence of skin irritation and sensitization potential. Therefore, OTC-I biomatrix is a potential medical device candidate for future clinical trials focusing on wound care management.

Evaluation of the antibacterial, antibiofilm, and anti-virulence effects of acetic acid and the related mechanisms on colistin-resistant Pseudomonas aeruginosa

BackgroundPseudomonas aeruginosa (P. aeruginosa) has been majorly implicated in the infection of burns, wounds, skin, and respiratory tract. Colistin is considered the last line of defense against P. aeruginosa infections. However, colistin is becoming increasingly invalid in treating patients infected with colistin-resistant (COL-R) P. aeruginosa. As one of the disinfectants used for wound infections, acetic acid (AA) offers good antibacterial and antibiofilm activities against P. aeruginosa. This study investigated the effects of AA on COL-R P. aeruginosa in terms of its antibacterial, antibiofilm, and anti-virulence properties and the corresponding underlying mechanisms.ResultsThe antimicrobial susceptibility and growth curve data revealed that 0.078% (v/v) AA exhibited good antibacterial activity against COL-R P. aeruginosa. Subinhibitory concentrations of AA were ineffective in inhibiting biofilm formation, but 4 × and 8 × of the minimum inhibitory concentration (MIC) was effective in removing the preformed biofilms in biofilm-eradication assays. The virulence results illustrated that AA inhibited COL-R P. aeruginosa swimming, swarming, twitching, and pyocyanin and elastase production. The analysis of the potential antibacterial mechanisms of AA on COL-R P. aeruginosa revealed that AA acted by increasing the outer and inner membrane permeability, polarizing the membrane potential, and decreasing the reduction potential in a concentration-dependent manner. The qRT-PCR results revealed that AA may inhibit the virulence of COL-R P. aeruginosa by inhibiting the expression of T3SS-related and QS-related genes.ConclusionsAA possesses antibacterial, antibiofilm, and anti-virulence properties that ultimately lead to the alteration of the bacterial membrane permeability, membrane potential, and reduction potential. Our findings indicated that AA is presently one of the effective treatment options for infections. A high concentration of AA (> 0.156% v/v) can be used to sterilize biofilm-prone surgical instruments, for hospital disinfection, and for treating the external wound, whereas a low concentration of AA (0.00975–0.039% v/v) may be used as an anti-virulence agent for adjuvant treatment of COL-R P. aeruginosa, thereby further improving the application value of AA in the treatment of infections.

Characterization of diet-dependent temporal changes in circulating short-chain fatty acid concentrations: A randomized crossover dietary trial

Production of SCFAs from food is a complex and dynamic saccharolytic fermentation process mediated by both human and gut microbial factors. Knowledge of SCFA production and of the relation between SCFA profiles and dietary patterns is lacking. Temporal changes in SCFA concentrations in response to 2 contrasting diets were investigated using a novel GC-MS method. Samples were obtained from a randomized, controlled, crossover trial designed to characterize the metabolic response to 4 diets. Participants (n = 19) undertook these diets during an inpatient stay (of 72 h). Serum samples were collected 2 h after breakfast (AB), after lunch (AL), and after dinner (AD) on day 3, and a fasting sample (FA) was obtained on day 4. The 24-h urine samples were collected on day 3. In this substudy, samples from the 2 extreme diets representing a diet with high adherence to WHO healthy eating recommendations and a typical Western diet were analyzed using a bespoke GC-MS method developed to detect and quantify 10 SCFAs and precursors in serum and urine samples. Considerable interindividual variation in serum SCFA concentrations was observed across all time points, and temporal fluctuations were observed for both diets. Although the sample collection timing exerted a greater magnitude of effect on circulating SCFA concentrations, the unhealthy diet was associated with a lower concentration of acetic acid (FA: coefficient: -17.0; SE: 5.8; P-trend = 0.00615), 2-methylbutyric acid (AL: coefficient: -0.1; SE: 0.028; P-trend = 4.13 × 10-4 and AD: coefficient: -0.1; SE: 0.028; P-trend = 2.28 × 10-3), and 2-hydroxybutyric acid (FA: coefficient: -15.8; SE: 5.11; P-trend: 4.09 × 10-3). In contrast, lactic acid was significantly higher in the unhealthy diet (AL: coefficient: 750.2; SE: 315.2; P-trend = 0.024 and AD: coefficient: 1219.3; SE: 322.6; P-trend: 8.28 × 10-4). The GC-MS method allowed robust mapping of diurnal patterns in SCFA concentrations, which were affected by diet, and highlighted the importance of standardizing the timing of SCFA measurements in dietary studies. This trial was registered on the NIHR UK clinical trial gateway and with ISRCTN as ISRCTN43087333.

Fermentation conditions for yeast selection and effect of yeast-bacterial interaction in developing a starter culture for tequila fermentation.

Similar to other beverages, tequila fermentation can be improved using selected native strains. During fermentation, yeast and bacteria frequently act together and can improve product quality. However, their influence during tequila fermentation is not fully understood. Three Saccharomyces cerevisiae strains isolated in a previous study were used to determine their fermentation parameters. Fermentation of agave juice by a selected yeast strain in the presence of seven native bacterial species (individually and in consortium) was also evaluated. Optimal temperature, initial fructose, and pH were determined using a rotatory central composite design, and concomitant fermentative parameters were used to select the best tequila yeast strain. The yeast strain Teq-199 presented the best fructose consumption (91.0%), ethanol production (33.5g/L), and yield (72%), as well as produced low concentrations of acetic acid (0.2g/L). The optimal fermentation temperature was 32°C, similar to that used at distilleries. During fermentation of agave juice by strain Teq-199 in the presence of individual native bacteria, the yeast dominated fermentation, while bacterial species impaired its quality due to lactic acid production (>3.3g/L). In the presence of a bacterial consortium, strain Teq-199 also dominated fermentation; however, a high concentration of acetic acid (6.5g/L) was generated, reducing the quality of the fermentation parameters. A comparison with a commercial wine strain K1-V1116, revealed that the strain Teq-199 exhibited the best fermentation parameters, indicating its potential use as an inoculant in industrial processing. Since bacteria were detrimental, distilleries should exert efforts to reduce their impact. PRACTICAL APPLICATION: The optimal fermentation conditions for pre-selected yeast strains isolated during tequila production were determined, which led to the selection of the best-adapted yeast strain to fulfill the actual requirements and conditions in the tequila industry. This study allows the selection of yeast strains that could be used by local producers. In addition, this yeast was able to overcome a well-adapted bacterial consortium, showing dominance throughout the fermentation process. This study is unique since it explored bacterial interactions during fermentation process and proposes a method to assess the effect of these concomitant microorganisms to properly select and design a starter culture.

Zein molecules in aqueous acetic acid solution: Self-assembling behaviors and formation mechanism of gluten-free doughs

The assembly behavior of biopolymers is affected by the type of solvent used. Previous investigations have focused on the self-assembly of zein molecules in aqueous ethanol. In this study, the self-assembly behavior of zein molecules in aqueous acetic acid solutions and their application in the development of zein-based gluten-free doughs was investigated. Zein molecules in low concentrations of acetic acid (30%–60%, v/v) assembled into irregular entities, in medium concentrations (70%, v/v) there was intermediate transition, and at high concentrations (80%–100%, v/v) they formed regular spheres. Interestingly, protein fibril formation was found to occur in 50% zein solutions in 50% and 60% acetic acid, as self-standing gels with solid-like properties resulted and the findings were verified using rheology. The 50% zein solutions in 70% acetic acid could form viscoelastic masses after anti-precipitation with the addition of excess water. Gluten-free dough with wheat-like properties was obtained by mixing the viscoelastic zein masses with wheat starch at room temperature. SEM observations showed that the formation mechanism for zein-based doughs involves the dispersion of starch granules in a three-dimensional zein network. These results will help to improve our understanding of zein assembly behavior regulation, and provide technical support for the development of zein in gluten-free food products.

Impact of acetate and propionate on anammox process in an expanded granular sludge bed: Evaluation of microbial community dynamics

Two expanded, granular sludge bed reactors were operated to investigate the effect of acetate acid (R1) and propionate acid (R2) on the anaerobic ammonium oxidization (anammox) process. It was indicated that low acetic acid (30 mg/L) and propionic acid (21 mg/L) concentration enhanced the performance of the two reactors. The heterotrophic denitrification process began to dominate when the organic acid concentration reached 270 and 191 mg/L, and the relative abundance of the heterotrophic denitrifying genus (Rubrivivax) increased from 0.5% and 3.3–6.2% and 8.9%, which the contribution of anammox in R1 and R2 was reduced to 43.62% and 68.08%, respectively. Better recovery efficiency in R2 was found after stopping adding acetate acid and propionate acid. The elevated relative abundance of ATP-blinding cassette transporters and membrane and intracellular structural molecules is the pattern of anammox bacteria (AnAOB) in response to organics inhibition. That explains the increase of abundance and gene copy number of the AnAOB genus (Candidatus Brocadia). AnAOB restored energy supply through the carbon fixation pathway and citrate cycle. Dok59 and Rubrivivax were the major heterotrophic denitrifying genus, with the latter preferring to use propionic acid.

Effects of malic or citric acid on the fermentation quality, proteolysis and lipolysis of alfalfa silage ensiled at two dry matter contents.

This study evaluated the effects of two organic acids on the fermentation of alfalfa silages at different dry matter (DM) contents. Alfalfa was wilted to DM contents of 30% (moderately low) and 38% (normal) and ensiled without additives (control) or treated with 0.6% fresh matter DL-malic acid (MA) or 0.6% fresh matter citric acid (CA) for 60days. After ensiling, silages with a normal DM were higher in pH, water-soluble carbohydrates (WSC) and DM loss (p<0.05) when compared to silages ensiled at a moderately low DM. The higher DM content also limited proteolysis in silages indicated by lower concentrations of ammonia N (NH3 -N). Compared with the control group, MA and CA-treated silages had lower pH, lower concentrations of acetic acid and NH3 -N but higher concentrations of lactic acid. The addition of MA and CA reduced DM losses in silages when compared to the control group except for MA-treated silage at a moderately low DM in which only numerically lower DM loss was observed. Malic acid and CA also resulted in a higher proportion of polyunsaturated fatty acids, especially in silages with a moderately low DM. Including MA and CA could promote silage fermentation, limit proteolysis and lipolysis at the lower and medium-to-high end of DM contents in alfalfa silages.

Effect of Solution Viscosity on the Precipitation of PSaMA in Aqueous Phase Separation-Based Membrane Formation.

Aqueous phase separation (APS) is a recently developed sustainable alternative to the conventional organic solvent based nonsolvent-induced phase separation (NIPS) method to prepare polymeric membranes. In APS, polyelectrolytes are precipitated from aqueous solutions through pH or salinity switches. Although APS differs from NIPS in the polymer and solvents, they share many tuning parameters. In this work, we investigate the APS-based preparation of membranes from poly(styrene-alt-maleic acid) (PSaMA) with a focus on acid concentration in the coagulation bath, and polymer and additive concentration in the casting solution. Nanofiltration membranes are prepared using significantly lower concentrations of acid: 0.3 M HCl compared to the 2 M of either acetic or phosphoric acid used in previous works. It is shown that higher polymer concentrations can be used to prevent defect formation in the top layer. In addition, acetic acid concentration also strongly affects casting solution viscosity and thus can be used to control membrane structure, where lower acetic acid concentrations can prevent the formation of macrovoids in the support structure. The prepared nanofiltration membranes exhibit a very low molecular weight cutoff (210 ± 40 dalton), making these sustainable membranes very relevant for the removal of contaminants of emerging concern. Understanding how the parameters described here affect membrane preparation and performance is essential to optimizing membranes prepared with APS towards this important application.

Brazilian cocoa hybrid-mix fermentation: Impact of microbial dominance as well as chemical and sensorial properties.

High-yield resistant hybrids are used in cocoa fermentation and result in chocolates with different sensorial profiles. This work aimed to characterize the fermentation microbiologically and physicochemically. Hybrids CEPEC 2004, FA13, PH15, and CEPEC 2002 were used for fermentation. The yeast, acetic acid bacteria, lactic acid bacteria, and mesophilic bacteria population were evaluated in their respective medium. Carbohydrates and acids were detected using a high-performance liquid chromatography system, and volatiles were analyzed using gas chromatography-mass spectrometry equipment. Finally, a consumer acceptance test followed by a check-all-that-apply question and a temporal dominance of sensations assessment was performed in chocolate. The fermentation resulted in a typical succession: yeast-dominated at first, followed by lactic acid, acetic acid, and mesophilic bacteria. In the pulp, carbohydrates and citric acid were consumed. Low concentrations of acetic acid (0.09-1.75 g/kg) were detected. Acids, esters, and alcohols were the most abundant groups. The chocolate profile resulted in sweet, acidic, and fruity, satisfying consumers' tastes. PRACTICAL APPLICATION: The cocoa hybrid-mix fermentation can improve the fermentation process and chocolate quality. The mixture generated a different sensory profile in comparison to other fermentations. The fruity chocolate was accepted and liked by consumers.

Electrocatalytic hydrogen evolution by cobalt triaryl corroles with appended ester and carboxyl on the 10-phenyl group

Two A2B cobalt triaryl corroles bearing ester (1) or carboxylic acid group (2) at the 10-para-phenyl group were prepared and used as homogeneous electrocatalysts for hydrogen evolution reaction (HER) with acetic acid and water as proton sources. CV results revealed the HER underwent two routes with [CoIII–H]– (EECC pathway) and [CoII–H]2– (ECEC pathway) as the intermediates at low acetic acid concentration. While the HER mainly went through the ECEC route at high acetic acid concentration. The HER turnover frequencies of 1 and 2 in neutral aqueous media were 291.8 and 190.6 h−1, respectively, at an overpotential of 838 mV. Unexpectedly, 1 exhibited significantly better HER activity than 2, showing the factors controlling electrocatalytic HER activity of cobalt corrole are complicated.

Reducing SO&lt;sub&gt;2&lt;/sub&gt; content in wine by combining High Pressure and glutathione addition

The aim of this work was to examine the potential of High Pressure (HP) technology as an alternative technique to SO2 addition for red wine preservation. It focused on producing wines with reduced added SO2 and the simultaneous addition of glutathione (GSH) as a natural antioxidant. Selected quality parameters of red wine samples from Mouchtaro grapes treated by HP using various pressure parameters were tested. HP processing studied was applied at 200, 400 and 600 MPa for 0, 5 and 15 min. The application of HP for a long duration resulted in a significant reduction in phenolic compound concentrations (TP) due to both extended polymerisation and reduced volatile acidity (VA) and acetic acid concentrations (AAC), which in turn was mainly due to better antimicrobial protection. Based on the changes to the contents of all TP, VA and AAC groups, processing for 5 min at 400 MPa was selected as the optimum HP condition. Red wine samples from Mouchtaro grapes containing 0, 20, 40, 60, 80 and 100 mg/L of SO2 and 10 mg/L of GSH were HP-treated under the selected pressure/time conditions. Untreated samples containing the same concentrations of SO2 and GSH were used as control samples. Indices such as AAC, Antioxidant activity (AOA), total anthocyanins, TP, mean Degree of Tannin Polymerisation (mDP) and the composition of volatiles was determined over a period of 12 months. Sensory analysis of the samples took place during the 12th month of storage. After the 12-month period, the pressurised samples with GSH showed higher content of total aldehyde/ketone and higher-alcohols, consistently lower concentrations of acetic acid, ethyl acetate and total esters, and lower VA values. Finally, based on the results obtained from the sensory analysis, untreated samples were characterised by "Red fruits" odours, whereas treated samples were distinguished by their "chocolate" aroma. These results suggest that HP could be used for the production of more "mature" wines. A reduced SO2 concentration of up to 40 or 60 mg/L may be sufficient for wine stabilisation when combining HP treatment and GSH additions, depending on grape variety.

Synthesis of 45S5 bioactive glass-ceramic using the sol-gel method, catalyzed by low concentration acetic acid extracted from homemade vinegar

In this paper, two different type of 45S5 bioactive glass-ceramic were compared. Both of them were prepared using the sol-gel method, with two different catalysts: 2 M nitric acid (NACBG) and 10 mM vinegar. Homemade vinegar (HMV) extracted from apples which contained up to 5% acetic acid, as an affordable and low concentration catalyst, was used for the synthesis of 45S5 bioactive glass ceramic called Homemade Vinegar Catalyzed Bioactive Glass (HMVCBG). The substitution of 2 M nitric acid by 87 mM acetic acid strongly reduces the concentration of the acid solution necessary for being a catalyst. The effect of these two catalysts on the structure, morphology, and properties of the bioactive glass-ceramics were investigated. Scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDXS) and Brunauer–Emmett–Teller (BET) were used to assess surface characteristics and specific surface area, which showed more uniformity and more specific surface area in HMVCBG. Crystallinity and composition were analyzed by X-ray diffraction (XRD), X-ray fluorescence (XRF) and Furrier transform infrared spectroscopy (FTIR) which showed some crystalline phases in BG. In-vitro bioactivity was studied in Phosphate Buffer Saline (PBS) and SEM results showed that HMVCBG has a more uniform hydroxyapatite layer and formation occurs more quickly. This due to the fact that hydroxyapatite is dissolved at a lower rate at higher pH values and it takes longer to form at a higher pH. HMV can form more numerous porosities and a more specific surface area because of higher pH of acetic acid. Hence, PBS solution penetrates to the depth of HMVCBG and hydroxyapatite nucleation form in more spots in the depth of HMVCBG. Thus, HMVCBG has a higher bioactivity level than NACBG.

A gentle acid-wash and pre-coating treatment of coral aggregate to manufacture high-strength geopolymer concrete

The coral reef fractures could be potentially used as aggregates for marine infrastructure construction, providing an alternative option to the high-cost gravel and sand aggregates. Coral aggregates are rough, porous and of low strength, which have a weak layer of minerals and microorganisms on the surface and a proportion of quartz inside pores. In the present study, using low concentration of acetic acid to pretreat coral aggregate was proposed to enhance the interface binding. When Portland cement was used as binder, the flexural and compressive strengths of cleaned coral aggregate concrete increased by 22.5% and 7.3%, respectively. Furthermore, the coral aggregate geopolymer concrete (CAGC) was prepared, given geopolymer acts as a strong binding and low porosity matrix, which is a promising material for the marine environment. To manufacture high-strength CAGC, a combined treatment method by gentle acid-wash cleaning and pre-coating of coral aggregate was proposed. The results showed that the mass loss rate of coral aggregate increased with the increase of acetic acid concentration and soaking time; the release of CO2 gas was helpful to remove the embedded sediment particles from the coral aggregates. Excessive acetic acid concentration and prolonged soaking time have adverse effects on the mechanical properties of CAGC, which was attributed to the corrosion of the internal skeleton of coral aggregate and the increase of connected pores. By using the gentle acid-wash and pre-coating method, a high-strength CAGC with compressive strength up to 60 MPa at 28-day was successfully manufactured, meeting the mechanical requirements of the most offshore construction requirements.

Intoxicación accidental por ácido acético glacial en niños

El ácido acético en bajas concentraciones se utiliza como vinagre para los alimentos, al que le da el sabor amargo y olor característico. También es un reactivo importante para la producción de otros compuestos orgánicos. Cuando está concentrado tiene usos industriales, como es el ácido acético glacial (99%) el cual se ingirió en forma accidental en este caso. Paciente de 8 años de edad quien tras posterior trauma cráneo encefálico leve es manejado en casa con ácido acético glacial que ingirió accidentalmente con posterior odinofagia, emesis e intolerancia a la vía oral. Hubo lesiones iniciales en faringe y amígdalas manejadas con el respectivo antibiótico. Al no haber mejoría consulta de nuevo por aumento del compromiso faríngeo, evidenciándose quemadura y lesión esofágica por cáusticos con estenosis. El seguimiento a los 6 meses, después de realizar dilataciones por medio de esofagoduodenoscopia, el paciente tuvo buena evolución clínica.

A nanoscale optical biosensor based on peptide encapsulated SWCNTs for detection of acetic acid in the gaseous phase

Abstract Biosensors play a key role in almost every field of human activity – ranging from biomedical diagnosis and point-of-care health monitoring to environmental monitoring and forensics. Single-walled carbon nanotubes (SWCNTs) are one of the most promising materials for near-infrared (NIR) fluorescence-based biosensing. Herein, we develop a reusable, drop-casted, real-time optical biosensor based on peptide-encapsulated SWCNTs for the detection of low concentrations of acetic acid in the air, at room temperature. While detection of NIR signal usually requires expensive and bulky equipment, here we use the (6,5) SWCNTs chirality whose peak fluorescence lies within the range of 970 nm – 1050 nm, enabling the usage of low cost and compact silicon-based detectors. We demonstrate the detection of wine spoilage based on excess gaseous acetic acid using peptide-wrapped SWCNT sensors down to 0.05% (v/v) acetic acid concentrations. Our results open new avenues for gas phase detection using NIR fluorescent SWCNT nanosensors.

Effects of malate, citrate, succinate and fumarate on fermentation, chemical composition, aerobic stability and digestibility of alfalfa silage

Abstract This study was to evaluate the effects of malate, citrate, succinate and fumarate on the fermentation quality, proteolysis and lipolysis and aerobic stability of alfalfa silage ensiled at two different dry matter (DM) contents. Alfalfa was harvested in the late bud to the early flower stage and wilted to DM contents of approximately 330 (normal DM) and 400 (high DM) g/kg fresh weight. The wilted and chopped alfalfa was ensiled in vacuum-sealing polyethylene plastic bags with treatments of control (distilled water), 0.5 % dl -malic acid (MA), 0.5 % citric acid (CA), 0.5 % sodium succinate (SS) and 0.5 % sodium fumarate (SF). All the application rates were based on the fresh weight of forage. After 60 days of ensiling, alfalfa silages ensiled at a normal DM had greater concentrations of lactic acid, acetic acid, non-protein N (NPN), ammonia N (NH3-N), greater aerobic stability and lower concentration of water soluble carbohydrates (WSC), DM loss when compared to the silages ensiled at a high DM (P