Asparagine Research Articles

Growth of L-asparagine monohydrate organic single crystals: An experimental and DFT computational approach for nonlinear optical applications

Good optical quality of L-asparagine monohydrate (C4H8N2O3.H2O) organic single crystal has been grown by adopting natural slow evaporation process at room temperature from aqueous solutions. The lattice parameters obtained by powder X-ray diffraction data revealed orthorhombic crystal system of the harvested crystal. The morphology and planes of the crystal have been identified. The molecular vibrations and functional groups have been specified by Fourier transform infrared (FTIR) spectroscopy studies. Energy dispersive X-ray (EDX) study has been availed to find out the elements constituting the crystal. Scanning electron microscopy, (SEM), provided the surface morphology of the crystal. The dependence of dielectric properties on frequency and temperature have been investigated and the electronic polarizability (α) has been determined. UV–vis spectral analysis shows that the crystal possesses good optical transmittance in the visible part of the energy spectrum. The optical band gap and the Urbach energy have been determined from lower absorption edge. Third order nonlinear susceptibility χ(3), nonlinear refractive index (n2), and linear susceptibility χ(1) have been calculated by Miller's generalized rule. The first-principle computation of band structure of electrons and the electron density of states have been discussed, which suggest that the crystals possess direct band gap. Density Functional Theory (DFT) with B3LYP function by Gaussian09W software was utilized to calculate HOMO-LUMO energy gap as well as non-linear optical parameters namely, linear polarizability (α), hyperpolarizability (β and γ) and dipole moment (μ) of L-asparagine monohydrate crystal. All the findings prove that L-asparagine monohydrate is a promising NLO crystal.

Solubility, molecular simulation, and dissolution thermodynamic of L-asparagine monohydrate in twelve pure solvents

In this paper, the solubility of L-asparagine monohydrate (LAM) in methanol, ethanol, water, n-propanol, n-butanol, i-propanol, i-butanol, acetonitrile, methyl acetate, ethyl acetate, butyl acetate, and propyl acetate, were measured using gravimetric method. Under standard pressure, a total of ten temperatures from 278.15 to 323.15 K every 5 K, were considered in this work. The experimental results showed that the solubility of LAM in single solvent increased with rising of temperature. The decreasing trend of solubility in alcoholic solvents was found to be methanol > ethanol > n-propanol > i-butanol > n-butanol > i-propanol, and water > methyl acetate > propyl acetate > butyl acetate > ethyl acetate > acetonitrile in non-alcoholic solvents. The maximum molar solubility of LAM was found in water (x1 = 0.009144, T = 323.15 K), and the minimum value was obtained in acetonitrile (x1 = 0.000001569, T = 278.15 K). Five thermodynamic models including Yaws model, the modified Apelblat equation, Wilson model, NRTL model, and UNIQUAC equation, were chosen to describe the solubility results, among which the UNIQUAC equation presented satisfactory correlations of solubility data by the analysis of relative regression deviations (ARD). The electrostatic potential surface of LAM and solvents were calculated and presented to investigate the intermolecular forces, as well as a density functional theory (DFT) calculation of molecular binding energies. The Hansen solubility parameters (HSPs) analysis was applied to investigate the similarity between solvents and LAM for further understanding of dissolution behaviors. It has been demonstrated that a combination of solvent polarities, molecular interactions, HSPs is contributed to the solubility of LAM in different solvents. Finally, the Gibbs energy, enthalpy and entropy of dissolution were determined, indicating that the dissolution of LAM is endothermic and entropy driven. The experimental solubility obtained is essential for further design, operation and optimization of LAM crystallization processes.

Asparagine as a signal for glutamine sufficiency via asparagine synthetase: a fresh evidence-based framework in physiology and oncology.

Among the 20 proteinogenic amino acids, glutamine (GLN) and asparagine (ASN) represent a unique cohort in containing a terminal amide in their side chain, and share a direct metabolic relationship, with glutamine generating asparagine through the ATP-dependent asparagine synthetase (ASNS) reaction. Circulating glutamine levels and metabolic flux through cells and tissues greatly exceed those for asparagine, and "glutamine addiction" in cancer has likewise received considerable attention. However, historic and recent evidence collectively suggest that in spite of its modest presence, asparagine plays an outsized regulatory role in cellular function. Here, we present a unifying evidence-based hypothesis that the amides constitute a regulatory signaling circuit, with glutamine as a driver and asparagine as a second messenger that allosterically regulates key biochemical and physiological functions, particularly cell growth and survival. Specifically, it is proposed that ASNS serves as a sensor of substrate sufficiency for S-phase entry and progression in proliferating cells. ASNS-generated asparagine serves as a subsequent second messenger that modulates the activity of key regulatory proteins and promotes survival in the face of cellular stress, and serves as a feed-forward driver of S-phase progression in cell growth. We propose that this signaling pathway be termed the amide signaling circuit (ASC) in homage to the SLC1A5-encoded ASCT2 that transports both glutamine and asparagine in a bidirectional manner, and has been implicated in the pathogenesis of a broad spectrum of human cancers. Support for the ASC model is provided by the recent discovery that glutamine is sensed in primary cilia via ASNS during metabolic stress.

Identifying targetable metabolic dependencies across colorectal cancer progression

Colorectal cancer (CRC) is a multi-stage process initiated through the formation of a benign adenoma, progressing to an invasive carcinoma and finally metastatic spread. Tumour cells must adapt their metabolism to support the energetic and biosynthetic demands associated with disease progression. As such, targeting cancer cell metabolism is a promising therapeutic avenue in CRC. However, to identify tractable nodes of metabolic vulnerability specific to CRC stage, we must understand how metabolism changes during CRC development. Here, we use a unique model system – comprising human early adenoma to late adenocarcinoma. We show that adenoma cells transition to elevated glycolysis at the early stages of tumour progression but maintain oxidative metabolism. Progressed adenocarcinoma cells rely more on glutamine-derived carbon to fuel the TCA cycle, whereas glycolysis and TCA cycle activity remain tightly coupled in early adenoma cells. Adenocarcinoma cells are more flexible with respect to fuel source, enabling them to proliferate in nutrient-poor environments. Despite this plasticity, we identify asparagine (ASN) synthesis as a node of metabolic vulnerability in late-stage adenocarcinoma cells. We show that loss of asparagine synthetase (ASNS) blocks their proliferation, whereas early adenoma cells are largely resistant to ASN deprivation. Mechanistically, we show that late-stage adenocarcinoma cells are dependent on ASNS to support mTORC1 signalling and maximal glycolytic and oxidative capacity. Resistance to ASNS loss in early adenoma cells is likely due to a feedback loop, absent in late-stage cells, allowing them to sense and regulate ASN levels and supplement ASN by autophagy. Together, our study defines metabolic changes during CRC development and highlights ASN synthesis as a targetable metabolic vulnerability in later stage disease.

Surface functionalization of graphene electrode using flavin AuNps for a realtime sensing of asparagine

Asparagine (ASN) is one of the major non-essential amino acids and helps to breakdown the toxic ammonia within the cell. The electrochemical detection of asparagine was performed by the surface functionalized screen-printed carbon (MSPEC) and screen-printed graphene electrodes (MSPEG) through flavin (Quercetin) based gold nanoparticles (AuNps). Cyclic voltammetry (CV) and Differential Pulse Voltammetry (DPV) were performed through MSPEC and MSPEG at single drop of analyte via DROPSENS. SEM and Electrochemical Impedance (EIS) examined for the surface characteristics, enhancement, and functionality of electrodes modified with flavin AuNps. The surface functionalized electrodes revealed excellent electrochemical sensor with high stability, selectivity, repeatability, and have a low limit detection of 0.001 nM. Also, sensors progression was found to occur through adsorption-controlled phenomena. The oxidation peak potential for asparagine in CV and DPV was well-expressed by the MSPEC and MSPEG, with potentials of +0.0881 V and +0.3141 V, respectively. Hence the flavin based AuNps is a new sensing platform for the consistent asparagine real-time sensor and the selective electrochemical detection of asparagine with an exceptionally low detection limit at one drop.

Achievement of therapeutic levels using dose-reduced peg-asparaginase in adult patients with acute lymphoblastic leukemia.

6530 Background: Peg-asparaginase (PEG) doses range from 2000-2500 IU/m2 in pediatric-inspired regimens for acute lymphoblastic leukemia (ALL). Pediatric PEG dosing in adolescents and young adults (AYAs) has resulted in improved outcomes, but PEG-associated toxicities increase with age and often limit its use. Therapeutic dosing is determined by asparagine (ASP) depletion for 14 days after dose; L-asparaginase levels can act as a surrogate marker of ASP depletion. We previously showed dose reduced PEG (defined as <2000 IU/m2) results in high rates of therapeutic L-asparaginase 7 days post PEG (Derman et al, Leuk Lymphoma 2020). Here we describe prolonged duration of ASP depletion and comparable toxicities after dose reduced PEG in adults with ALL. Methods: Patients ≥18 years with ALL or lymphoblastic lymphoma (LBL) who received PEG from 1/1/2008 to 9/28/2023 were identified for retrospective chart review. Those with ≥1 PEG trough level (defined as 10-20 days after dose) were included. The primary endpoint was therapeutic PEG levels (≥0.1IU/mL L-asparaginase) at 7 and 14 days post administration, with secondary endpoint being induction grade 3+ toxicities (CTCAE v.5.0). Results: 49 patients met inclusion criteria, of which 48 received PEG during induction. Median age was 34.7 (range 18-66), 67% were male and 53% had B-cell ALL. 17 (35%) received an induction dose ≤ 500 IU/m2, 22 (46%) received 501 to ≤1000 IU/m2 and 9 (19%) received >1000 IU/m2. Induction median dose was 1000 IU/m2. Among those with PEG trough levels, 79% were therapeutic after induction; of note, 4 patients were transitioned from PEG to Erwinia asparaginase due to silent inactivation. During induction, 23 (48%) patients had ≥1 grade 3+toxicity, including 5 (10%) with hepatotoxicity, 1 (2%) with pancreatitis, and 2 (4%) with a thrombotic event. There was no statistical relationship between dose level and toxicities (p=.8). Conclusions: This study demonstrates durability of therapeutic L-asparaginase levels and ASP depletion that persists 14 days despite dose reduction. There were decreased rates of hepatotoxicity and comparable rates of pancreatitis and thrombotic events compared to rates reported in CALBG 10403 (C10403) (Stock et al, Blood 2019), which utilized standard pediatric dosing. In addition, our cohort’s median age was significantly older than those treated on C10403. This suggests PEG dose reduction may offer similar therapeutic ASP depletion with comparable or reduced toxicities. Dose reduction should be studied prospectively in AYAs with ALL. [Table: see text]

Influence of pH on growth, structural, thermal, linear and nonlinear optical properties of L-asparagine monohydrate single crystal

This report presents investigation on influence of pH on growth, structural, thermal, linear and nonlinear optical properties of L-asparagine monohydrate (LAM) single crystal for the first time. Single crystals of LAM were grown at different pH by solution growth method by allowing slow evaporation of solvent. Crystal grown at pH 6.4 grows slowly as compare to other crystals grown at other pH values. The slight variation in lattice parameters of grown crystals has been confirmed by powder X-ray diffraction study. FT-IR study confirms the presence of functional groups of LAM in all grown crystals. Influence of pH on optical quality of crystals has been discussed. The crystal grown at pH 5.4 has maximum optical transparency and shows 2 and 20 % more transmission than crystals grown at pH 4.4 and 6.4, respectively. Other optical parameters like cutoff wavelength (λmax), band gap (Eg), linear refractive index (n), reflectance, extinction coefficient (k), electrical susceptibility (χ), optical conductivity(σop), electrical conductivity (σel) and Urbach energy (Eu) of all crystals have been evaluated from transmission data. The LAM crystal grown at pH 6.4 show high values of third order nonlinear optical parameters, as compare to other grown crystals, that attest its suitability for applications like higher harmonic generation, optical switching, optical limiting and other photonic applications over other grown crystals. Thermal stability of the grown crystals has been attested by TG-DTA study.

Investigation of particle flow effects in slug flow crystallization using the multiscale computational fluid dynamics simulation

This article discusses the development of a new computational fluid dynamics (CFD) model, the MVP (MP-PIC coupled with VOF and PBE) method, which predicts the slug flow crystallization phenomenon. The model is capable of predicting the flow of gas–liquid-solid phases and the associated chemical and particle changes. The MVP model is validated through a comparison with an experimental study on LAM (L-asparagine monohydrate) crystallization, and the results demonstrate its ability to accurately predict the three-phase fluid flow with particle size variation. In particular, we have been able to predict the effect of slug length change on particle mixing and predict hydrodynamic factors such as the particle streamlines and the circulation number of the particle phase via case studies. Overall, the MVP model is expected to offer a new way to accurately predict slug flow crystallization and provide valuable information for the process intensification of crystallization.

Growth of L asparagine monohydrate doped potassium dihydrogen phosphate semiorganic crystals and its structural, thermal and optical properties

A novel semiorganic crystal is harvested by doping organic amino acid L asparagine monohydrate (LAM) with inorganic compound Potassium dihydrogen phosphate (KDP) by adopting slow evaporation method. Rietveld refinement of the XRD data was performed and the structural study exhibits single phase nature of the LAM doped KDP (LAM-KDP) crystals with a slight decrease in c-axis of the unit cell parameters. Other crystallographic parameters such as crystallite size and strain were also evaluated. The interaction of LAM with KDP was studied from FT-IR analysis by detecting functional groups. The constituting elements of the crystal were identified by energy dispersive X-ray (EDX) analysis. Etching study has been employed to study surface morphology of these crystals. From UV–vis transmittance data, optical band gap and different optical constants like Urbach energy, dielectric constants, electrical and optical conductivities were evaluated. Optical transparency of the LAM-KDP crystals is observed to increase. The third order nonlinear susceptibility χ(3) and nonlinear refractive index n2 of the grown crystals have been predicted using empirical Miller's rule. The value of χ(3) has increased from 1.87 × 10−13 esu to 4.29 × 10−13 esu due to LAM doping. Change in enthalpy (ΔH), change in Gibb's free energy (ΔG) and activation energy Ea during chemical reaction were calculated by thermogravimetric analysis (TGA). Thermal decomposition characteristics of the crystals were analyzed by differential scanning calorimetry (DSC). The high transparency of LAM-KDP crystals in the entire visible spectrum and larger values of nonlinear susceptibility χ(3) and nonlinear refractive index n2 make the synthesized crystal applicable for NLO and optoelectronic devices applications.

Response of bacterial communities, enzyme activities and dynamic changes of soil organic nitrogen fractions to six-year different application levels of biochar retention in Northeast China

Composition and availability of soil organic nitrogen play a key role in soil N retention and supply. The application of traditional chemical fertilizers can improve soil production and crop yields. However, it also leads to low N utilization efficiency and soil solidification. Previous studies have shown that fertilizers added with biochar can improve soil fertility and facilitate soil nutrient transformation by regulating soil biological indicators. However, whether biochar used with fertilizers can promote nutrient cycling in the long term, which remains to be tested. Therefore, this study aims to explore the long-term effects of biochar with different levels used with fertilizers on soil fertility, N supply potential of organic N, and microbial communities, thus, providing a theoretical reference for the rational management of biochar applications. In this study, a field experiment was carried out from 2013 to 2018 assess dynamic changes in organic N fractions and diversity and richness of microbial communities under the impacts of chemical fertilizers combined with different levels of biochar. Biochar with no amendment (CK), biochar with 15.75 t ha−1 (BC1), biochar with 31.5 t ha−1 (BC2), and biochar with 47.25 t ha−1 (BC3) are four biochar levels that were tested in this study. The results show that compared with CK, those other three biochar levels can increase soil organic matter, C/N, and pH values. Acid-hydrolysable N (AHN) makes a major contribution to organic N in soil. Biochar retention for six years has significantly affected AHN levels, as well as its four fractions, namely, amino acid N (AAN), acid-hydrolysable ammonium N (AN), amino sugar N (ASN), and hydrolysable unknown N (HUN). Some vital biological characteristics, with which each AHN fraction is primarily regulated, can be altered with the application of biochar. That is, AAN is mainly controlled by enriched Verrucomicrobia, Cyanobacteria, Glucosylbacteria, and Nitrospira, and reduced soil urease, while AN is mainly controlled by enriched Verrucomicrobia, Bacteroidetes, Gemmatimonadetes, Acidobacteria, and Proteobacteria. ASN is regulated by enriched Acidobacteria and depleted soil protease, while HUN is regulated by Gemmatimonadetes and enriched soil nitrate reductase. It has been found that microbial and soil enzyme activities are involved in N cycle processes, indicating that the formation of AHN fractions is closely associated with biochar-induced specific microbial and enzyme activities. This study has provided new insights into the influences of biochar with different levels on distribution of soil organic N fractions, and shifts in soil enzyme activities and microbial communities.

Growth, structural, thermal, and optical characteristics of L-asparagine monohydrate doped magnesium sulphate heptahydrate semiorganic crystals

A novel semi-organic crystal has been grown using slow evaporation technique by doping organic compound L-asparagine monohydrate (C4H8N2O3·H2O) with inorganic material Magnesium sulphate heptahydrate (MgSO4·7H2O). The crystallographic parameters like strain, dislocation density and crystallite size were calculated by powder X-ray diffraction method. Functional groups were identified and bond length, force constants were calculated from FT-IR spectroscopy. Energy dispersive X-ray (EDX) analysis was used to identify the constituent elements of the crystal. Kinetic and thermodynamic parameters, such as, activation energy Ea, change in Gibb's free energy (ΔG) and change in enthalpy (ΔH) have been determined by thermogravimetric analysis (TGA) analysis. Ea, ΔH and ΔG show positive values and change in entropy (ΔS) shows negative ones. The thermal degradation behavior of the crystals has been analyzed by differential scanning calorimetry (DSC) analysis. Various optical constants such as optical band gap, lattice dielectric constant, absorbance, extinction coefficient, the ratio of free charge carrier concentration to the effective mass, Urbach energy, optical and electrical conductivities were estimated from UV–vis transmittance data. High optical conductivity (1010 s−1) justifies the good photo response nature of the semi-organic crystal.

Machine learning investigation to predict corrosion inhibition capacity of new amino acid compounds as corrosion inhibitors

This scientific paper aims to investigate the best machine learning (ML) for predicting the corrosion inhibition efficiency (CIE) value of amino acid compounds. The study applied a quantitative structure–property relationship (QSPR) model based on an ML approach to predict the CIE values of three new amino acid compounds, namely L-asparagine (LA), L-isoleucine (LI), and L-proline (LP). The result is that the Gradient Boosting Regressor (GBR) model is proven to be the best predictive model based on the coefficient of determination (R2) and root mean square error (RMSE) metrics used. The study found that the three amino acid compounds LA, LI, and LP tested had high CIE values, ranging from 90.49% to 93.67%. These results are also relevant to the CIE values resulting from experimental studies and show a trend that is by the adsorption energy trend. This engineering breakthrough can be used to predict the corrosion inhibition properties of new compounds before experimental synthesis.

Comparison of a rapid enzymatic assay with column chromatography and nuclear magnetic resonance methods for free asparagine detection and quantification in wheat

A rapid, reliable, and user-friendly method that does not require complex sample preparation and sophisticated instrumentation will fulfill an emerging demand for free asparagine (ASN) analysis to ascertain acrylamide-related food safety issues in baked cereal products. This study validated a new method for wheat free asparagine analysis by comparing a rapid enzymatic test with two established analytical methods: UPLC and 1H-NMR using asparagine standards and whole-wheat flours with a range of free asparagine concentrations. For method validation, various quality parameters were assessed, including accuracy, precision, and sensitivity. Experimental and time costs associated with the analyses were estimated. The rapid test method had consistent accuracy, excellent precision of 1.0 or less (CV%), good sensitivity (0.0389 AU L mg−1) of free asparagine signal detection, and the least cost for experimental materials and instrument usage. A strong correlation (r = 0.997) between the results generated by the rapid enzymatic test and the UPLC method for free ASN quantification in whole-wheat flour was obtained. Overall, the rapid test method is recommended for ASN analysis in simple laboratory environments or in industrial applications.

Methylseleninic acid overcomes gefitinib resistance through asparagine-MET-TOPK signaling axis in non-small cell lung cancer cells

Acquired resistance compromises the efficacy of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI)-based therapy for non-small cell lung cancer (NSCLC), and activation of hepatocyte growth factor receptor (MET) is one of the pivotal strategies for cancer cells to acquire refractory phenotype. However, the mechanisms involved in regulating MET activity remain to be further elucidated. Using gefitinib-resistant HCC827GR cell line as a model, we unraveled that the dysregulated amino acid metabolisms reflected by elevated expression of cysteine-preferring transporter 2 (ASCT2), cystine/glutamate antiporter solute carrier family 7 member 11 (SLC7A11) and asparagine synthetase (ASNS) might contribute to survival advantage of HCC827GR cells, and rendered the cells more sensitive to asparagine (ASN) deprivation compared to parental HCC827 cells. We further identified that the increased ASNS expression is a contributing factor for the activation of MET in HCC827GR cells. More importantly, we found that methylseleninic acid (MSeA), a precursor of methylselenol, effectively suppressed tumor growth in HCC827GR xenograft model, which is associated with decrease of intracellular ASN content along with inactivation of MET- T-lymphokine-activated killer cell-originated protein kinase (TOPK) signaling axis. Finally, we demonstrated that combination of MSeA and gefitinib induced a synergistic growth inhibition in HCC827GR cells. The findings of our work reveal that ASN-MET-TOPK signaling axis as a novel mechanism contributed to gefitinib-resistance and combined utilization of gefitinib and MSeA holds potential to improve the efficacy for gefitinib-resistant NSCLC.

Moisture effects on microbial protein biosynthesis from ammonium and nitrate in an unfertilised grassland

Incorporation of nitrogen (N) into soil microbial protein is central to the soil N cycle to mitigate N losses and support plant N supply. However, the effect of factors, such as water filled pore space (WFPS), which influence inorganic N transformations and losses, and thus microbial incorporation, are only poorly understood. This work aimed to bridge this gap, using compound-specific 15N-stable isotope probing to quantify microbial assimilation into the largest defined soil organic N pool, protein-N. This approach applied differentially 15N-labelled ammonium nitrate (NH4NO3) to an unfertilised UK grassland in a soil mesocosm study over 10 days. The soil microbial community showed a strong preference for NH4+ over NO3−, which varied with WFPS (85% > 55% > 70%). This preference decreased for amino acids further in biosynthetic proximity to the transamination step in amino acid biosynthesis. Combined incorporation of NH4+ and NO3− increased total hydrolysable amino acid-N concentration linked to WFPS (55% ∼ 85% > 70%). Incorporation rates of applied 15N showed the same trend as NH4+ preference with WFPS (85% > 55% > 70%), which is related to microbial activity and nutrient mobility. Despite differences in incorporation, when normalised to soil available N, incorporation was comparable in the short-term. Mechanistic control of WFPS via assimilation into the largest soil organic N pool is important to mitigate potential positive feedbacks to N losses and support N supply to plants.

Post-Fire Evolution of Soil Nitrogen in a Dahurian Larch (Larix gmelinii) Forest, Northeast China

This study investigates the evolution of soil nitrogen (N) contents and forms along a 17-year wildfire chronosequence in the Daxing’an Mountains. Surface soil and subsoil samples were collected during different recovery periods after wildfires. Then, the mineral N (i.e., NH4+-N and NO3−-N) and amino acid-N (AAN) contents in the soil extracts were measured and used to calculate the different ratios as indicators of the N forms. The results showed that the NH4+-N, NO3−-N, and AAN contents increased immediately after the wildfire. With vegetation restoration, the NH4+-N and NO3−-N contents became similar to those of unburned forests nine years and two months after the wildfire, respectively. The AAN content was mostly recovered one year post-fire. The wildfire did not lead to substantial changes in the mineral N form, but the ratio significantly increased and recovered after nine years. The soil available N form was altered by wildfires. After the wildfire, the dominant available N form changed from equivalent AAN and mineral N to a predominance of AAN in the growing season, and the predominance of AAN decreased to varying degrees in the non-growing season. With the recovery of the white birch and Dahurian larch, AAN again became the dominant N form, but the predominance of AAN was low before the freeze-up. Our study demonstrates that wildfires directly affect the soil N contents and forms, and such effects could be diminished by the restoration of the soil environment and vegetation over time.

Synthesis and characterization of l-asparagine monohydrate potassium dichromate (LAMPDC): novel material for optical limiting applications

Synthesis and characterization of l-asparagine monohydrate potassium dichromate (LAMPDC): novel material for optical limiting applications

Long-term nitrogen fertilization-induced enhancements of acid hydrolyzable nitrogen are mainly regulated by the most vital microbial taxa of keystone species and enzyme activities

It is well known that nitrogen (N) fertilizer input is required to improve crop productivity, but we lack a comprehensive understanding of how elevated N input changes the formation of soil acid hydrolyzable nitrogen (AHN) by adjusting the most vital microbial taxa of keystone species of microbial communities and enzyme activities. A 15-year field experiment comprising four levels of inorganic N fertilization was conducted to identify the most important bacterial and fungal taxa of the keystone species derived from cooccurrence networks as well as the vital enzyme activities at the bell mouth and maturity stages. Long-term N fertilization significantly increased the levels of AHN along with its four fractions, including amino acid N (AAN), ammonium N (AN), amino sugar N (ASN), and hydrolysable unidentified N (HUN), by 30.1–118.6 %, regardless of growth stage. Some most vital microbial taxa of keystone species and enzyme activities, which changed in response to N fertilization, mainly regulated each ANH fraction, that is, AHN and AN were mainly controlled by the enrichment of Nocardioides and β-1,4-N-acetyl-glucosaminidase (NAG), as well as by the reduction of Anaerolinea and urease (UR), AAN was determined by the enrichment of Hannaella and depletion of Penicillium, ASN was regulated by the enrichment of Hannaella and Arthrobacter, and HUN was influenced by the reduction of Penicillium and enrichment of Nitrosospira. These microbial genera have been found to be involved in dissimilatory nitrate reduction to ammonium (DNRA) and nitrification/denitrification processes and the two enzyme activities involved in organic N degradation and N-releasing processes, suggesting that the formation of AHN fractions was closely associated with specific functional microbial taxa and enzyme activities induced by N fertilization. Our results provide new insights into the associations among increased N input, altered formation of soil organic N, and shifts in microbial communities and enzyme activities.

Evaluation of synthesized biosurfactants as promising corrosion inhibitors and alternative antibacterial and antidermatophytes agents

This study investigated different amino acid-based surfactants (AASs), also known as biosurfactants, including sodium N-dodecyl asparagine (AS), sodium N-dodecyl tryptophan (TS), and sodium N-dodecyl histidine (HS) for their potential anticorrosion, antibacterial, and antidermatophyte properties. The chemical and electrochemical techniques were employed to examine the copper corrosion inhibition efficacy in H2SO4 (1.0 M) solution at 298 K. The results indicated their promising corrosion inhibition efficiencies (% IEs), which varied with the biosurfactant structures and concentrations, and the concentrations of corrosive medium. Higher % IEs values were attributed to the surfactant adsorption on the copper surface and the production of a protective film. The adsorption was in agreement with Langmuir adsorption isotherm. The kinetics and mechanisms of copper corrosion and its inhibition by the examined AASs were illuminated. The surfactants behaved as mixed-kind inhibitors with minor anodic priority. The values of % IEs gained from weight loss technique at a 500 ppm of the tested surfactants were set to be 81, 83 and 88 for AS, HS and TS, respectively. The values of % IEs acquired from all the applied techniques were almost consistent which were increased in the order: TS > HS ≥ AS, establishing the validity of this study. These surfactants also exhibited strong broad-spectrum activities against pathogenic Gram-negative and Gram-positive bacteria and dermatophytes. HS exhibited the highest antimicrobial activity followed by TS, and AS. The sensitivity of pathogenic bacteria varied against tested AASs. Shigella dysenteriae and Trichophyton mantigrophytes were found to be the most sensitive pathogens. HS exhibited the highest antibacterial activity against Shigella dysenteriae, Bacillus cereus, E. coli, K. pneumoniae, and S. aureus through the formation of clear zones of 70, 50, 40, 39, and 35 mm diameters, respectively.AASs also exhibited strong antifungal activity against all the tested dermatophyte molds and fungi. HS caused the inhibition zones of 62, 57, 56, 48, and 36 mm diameters against Trichophyton mantigrophytes, Trichophyton rubrum, Candida albicans, Trichosporon cataneum, and Cryptococcus neoformans, respectively. AASs minimal lethal concentrations ranged between 16 to 128 µg/ml. HS presented the lowest value (16 µg/ml) against tested pathogens followed by TS (64 µg/ml), and AS (128 µg/ml). Therefore, AASs, especially HS, could serve as an effective alternative antimicrobial agent against food-borne pathogenic bacteria and skin infections-associated dermatophyte fungi.

Structural and morphological behaviours of l-Asparagine monohydrate at shocked conditions

Studies on the dynamic shock impact on solids also provide a magnificent scope of understating the stability of materials that are needed for high-pressure applications. Based on the impending investigations arising out of the observed experimental results of the shock-wave impact on solids, it is very much revealed that the impact of shock waves on molecular crystals is not yet well understood; especially amino acid crystals. Hence the present work deals with the assessment of crystallographic phase stability of l-Asparagine monohydrate (C4H8N2O3·H2O) amino acid powder samples against shocked-conditions and the results have been analyzed by X-ray powder diffractometry and scanning electron microscopy. The results of XRD and SEM reveal that the mother crystallographic phase of the title sample has significantly changed without inducing any crystallographic phase-transition and the observed structural modifications are discussed on the basis of previous publications reported on the static high-pressure study on the title sample.