The Role of Acid Concentration on Band Gap Shrinkage in Cellulose Nanocrystals Fabricated from Water Hyacinth

In this study, the fingerprint of the acid concentration during the hydrolysis process on the optical band gap of cellulose nanocrystals (CNCs) has been systematically studied. The CNCs have been prepared using hydrochloric acid at a hydrolysis temperature of 50°C and at a constant hydrolysis time of 4 hours but with varying hydrochloric cid concentrations of 5%, 10% and 15%. The crystalline structure and phase identification of the CNCs have been studied using XRD technique. UV-Vis Spectroscopy has been done and the optical band gap energy calculated by performing the Tauc’s plot. From the study, the grain size has been found to decrease with acid concentration while the band gap energy has been found to increase with increasing acid concentration. Further, the optical band gaps of the CNCs have been found to decrease with the increase in crystallite size. This shrinkage of the band gap has been attributed to the increased impurity concentration leading to the narrowing of the band gap due to the emerging of the impurity band formed by the overlapped impurity states

Electrocatalytic H2 evolution promoted by a bioinspired (N2S2)Ni(II) complex

We have investigated a bioinspired (N2S2)Ni(II) electrocatalyst that produces H2 from CF3CO2H with a turnover frequency (TOF) of ~1,250 s–1 at low acid concentration (<0.043 M) in MeCN. A mechanism...

Dynamic Changes of Intestinal Microbiota and Metabolite Composition in Pre-Weaned Beef Calves

Background: Gut microbes and their metabolites are essential for maintaining host health, but few studies have elucidated the combined effects of microbial and metabolite interactions on the growth and development of pre-weaned calves over time. Therefore, the aim of this study was to explore dynamic changes of intestinal microbiota and metabolites among newborn calves classified as healthy, sub-healthy, and those that died early during their growth and development.Results: 16S rRNA gene sequencing and metabolomics analysis was employed to track the dynamic changes in faecal microflora abundance and metabolite levels (fatty acids and amino acids) in calves before weaning. The results demonstrated that the alpha diversity of the faecal microbiota increased with calf growth and development. Specifically, the abundances of Porphyromonadaceae bacterium DJF B175 and Alistipes shahii gradually increased in healthy calves over time. Inversely, the abundance of Enterobacteriaceae was higher in the sub-healthy group than in the healthy group. Meanwhile, the faeces of calves in the early death group had significantly higher medium-long-chain fatty acid concentration than those in the healthy group. The faecal amino acid concentration decreased significantly with weekly age in the healthy and sub-healthy groups.Conclusions: The study findings provide a new understanding of calf growth and development prior to weaning. Even under the same management conditions, microorganisms and their metabolites interact to play different dynamic regulatory roles in the growth and development of newborn calves. Further studies are warranted to determine the mechanisms involved.

Organic Acid-Catalyzed Subcritical Water Hydrolysis of Immature Citrus unshiu Pomace

Immature Citrus unshiu pomace (ICUP) was hydrolyzed under organic acid-catalyzed, subcritical water (SW) conditions to produce flavonoid monoglucosides (hesperetin-7-O-glycoside and prunin) and aglycons (hesperetin and naringenin) with high biological activities. The results of single-factor experiments showed that with 8 h of hydrolysis and an increasing citric acid concentration, the yield of flavonoid monoglucosides (hesperetin-7-O-glycoside and prunin) increased from 0 to 7% citric acid. Afterward, the hesperetin-7-O-glycoside yield remained constant (from 7 to 19% citric acid) while the pruning yield decreased with 19% of citric acid, whereas the aglycon yield increased continuously. In response surface methodology analysis, a citric acid concentration and hydrolysis duration of 13.34% and 7.94 h were predicted to produce the highest monoglucoside yield of 15.41 mg/g, while 18.48% citric acid and a 9.65 h hydrolysis duration produced the highest aglycon yield of 10.00 mg/g. The inhibitory activities of the SW hydrolysates against pancreatic lipase (PL) and xanthine oxidase (XO) were greatly affected by citric acid concentration and hydrolysis duration, respectively. PL and α-glucosidase inhibition rates of 88.2% and 62.7%, respectively, were achieved with 18.48% citric acid and an 8 h hydrolysis duration, compared to 72.8% for XO with 16% citric acid and 12 h of hydrolysis. This study confirms the potential of citric acid-catalyzed SW hydrolysis of ICUP for producing flavonoid monoglucosides and aglycons with enhanced enzyme inhibitory activities.

Comprehensive Study of the Action of Corrosion Inhibitors Based on Quaternary Ammonium Compounds in Solutions of Hydrochloric and Sulfamic Acids

Acid treatments are one of the methods for intensifying oil and gas production. Corrosion is a significant factor affecting the performance of oilfield equipment. There are many different methods of preventing corrosion, but corrosion inhibitors are most commonly used in industry. The protective effect of the inhibitor is directly determined by the effective adsorption of surfactants on the metal surface. For an indirect assessment of the adsorption of the inhibitor, a comprehensive research method is proposed based on the determination of the interfacial tension of acid compositions and steel plates’ contact angle of wetting after corrosion tests. It was found that in hydrochloric acid the adsorption of the inhibitor IC-1 reaches a maximum after 6 h, an increase in the acid concentration in the range of 5–15% wt. has a negative effect on the activity of the inhibitor. For sulfamic acid, the maximum adsorption of the IC-2 inhibitor is observed after 24 h, an increase in acid concentration has a positive effect on surfactants.

Assessment on the Effect of Sulfuric Acid Concentration on Physicochemical Properties of Sulfated-Titania Catalyst and Glycerol Acetylation Performance

In this research, a solid acid catalyst was synthesized to catalyse glycerol acetylation into acetins. The sulphated-titania catalysts were prepared via the wet impregnation method at different sulfuric acid concentrations (5%, 10%, 15%, and 20%) and denoted as 5SA, 10SA, 15SA, and 20SA, respectively. The synthesized catalysts were characterized using FTIR, XRD, TGA, BET, NH3-TPD, XRF, and SEM-EDX. The synthesized catalysts were tested on glycerol acetylation reaction at conditions: 0.5 g catalyst loading, 100–120 °C temperature, 1:6 glycerol/acetic acid molar ratios, and 2–4 h reaction time. The final product obtained was analysed using GC-FID. An increment in sulfuric acid concentration reduces the surface area, pore volume, and particles size. However, the increment has increased the number of active sites (Lewis acid) and strong acid strength. 15SA catalyst exhibited excellent glycerol conversion (>90%) and the highest selectivity of triacetin (42%). Besides sufficient surface area (1.9 m2 g−1) and good porosity structure, the great performance of the 15SA catalyst was attributed to its high acid site density (342.6 µmol g−1) and the high active site of metal oxide (95%).

Enrichment of amino acids from its aqueous solution by ultrasonic atomization and ultrafine bubbles

The enrichment characteristics of amino acids by ultrasonic atomization were investigated. Samples were aqueous solutions of L-phenylalanine and L-tyrosine. The ratio of amino acid concentration in the mist to that in the solution was defined as the enrichment factor. As the flow rate of carrier gas became higher, the collection mass of mist increased and the enrichment factor decreased. The enrichment factor depended on the solution pH. The enrichment factor increased with decreasing amino acid concentration in the solution and enhanced by the addition of ultrafine bubbles.

Formulation of Biodegreaser Made from Palm Oil Methyl Ester Sulfonate Surfactant with Oxalic Acid Additive

The development of bio degreaser made from palm oil surfactant aims to substitute bio degreaser made from petroleum surfactant which is less environmentally friendly. The development was carried out by formulating palm methyl ester sulfonate (MES) surfactant with oxalic acid as metal or non-metal cleaning agent. The purpose of this study was to obtain the best concentration of oxalic acid in the bio degreaser formulation. The concentrations of oxalic acid tested were 7, 8, and 9%. The best concentration of oxalic acid was determined based on the results of characteristic tests and detergency tests, namely 7% oxalic acid concentration. The resulting bio degreaser product has a pH of 1.6; viscosity 1.39 cp; specific gravity of 1.012; surface tension 32 dyne/cm and detergency power 84%. Furthermore, the resulting bio degreaser was added with Diethanolamioda (DEA) surfactant. The purpose of adding DEA surfactant is to increase the pH and lower the surface tension. The formulation results showed an increase in pH from 1.6 to 3.2 and a decrease in surface tension from 31.97 dyne/cm to 28.70 dyne/cm. In addition, there was an increase in viscosity from 1.39 cp to 1.62 cp and specific gravity from 1.012 to 1.018.