Typical Peak Research Articles

Study of Cellulose Extraction from Robusta Coffee Husk Using NaOH Solution

This study reports on manufacturing cellulose from robusta coffee husks through a solid-liquid extraction process. A high yield of cellulose can be achieved by extraction using 3.5% HNO3 at a temperature of 100 oC with a gain of 35.4%. Meanwhile, the extraction process with 4.5% HNO3 at a temperature of 80 oC only achieved a yield of 32.8%. From the results of this study, it can be seen that the smaller the concentration of HNO3 used and the higher the temperature, the greater the yield of cellulose produced. The X-ray diffraction pattern shows high peaks appearing at an angle of 2θ around 22.5o; this area is a typical peak of the cellulose structure. High crystallinity was obtained at a concentration of 3.5% HNO3 at a temperature of 100 oC at 82.47%, while the lowest crystallinity was found at a 5.5% HNO3 concentration at a temperature of 100 oC at 74.27%. The decrease in crystallinity was caused by the high temperature and concentration of HNO3, which caused the acid to penetrate quickly into the cellulose tissue layer and hydrolyze the crystalline regions of cellulose. FT-IR analysis showed a high absorption area at 3314 cm-1 and a low absorption area at 1028 cm-1, typical of Robusta coffee husk cellulose. The absorption located around the 3314 cm-1 bands is a stretch of the –OH group and the absorption in the 1028 cm-1 band is related to the -CH2 group. SEM can show the morphology of cellulose with smaller and uniform crystal dimensions with a scale of 20 µm.

A novel polysaccharide from Boletus edulis: Extraction, purification, characterization and immunologic activity

A novel polysaccharide (BEP) was extracted from Boletus edulis, and its structural characteristics and immunologic activity were evaluated. Our findings revealed that BEP (139 kDa) contained Man, Glc, and Gal in the molar ratio of 1:0.15:0.17 with typical characteristic absorption peaks of polysaccharides. Moreover, the results of methylation and 1D/2D NMR spectroscopy indicated that the backbone of BEP was →6)-α-Manp-(1→ and →3,6)-α-Manp-(1→, with the side chain →3)-β-Manp-(1→, →3)-α-Galp-(1→ and α-Glcp-(1→). The immunological activity tests demonstrated that the BEP could enhance phagocytosis of peritoneal macrophages and secrete NO and cytokines in a dose-dependent by activated macrophage. It was noteworthy that the secretions of NO, IL-6 and TNF-α at 400 μg/mL concentration were increased by 25.50%, 191.67% and 196.05% compared with the control group, respectively. The results illustrated that BEP was a novel polysaccharide, which may be marked as an immunologic agent in the food, pharmaceutical and cosmetic industries.

Enhanced electrochemical activity and durability of a direct ammonia protonic ceramic fuel cell enabled by an internal catalyst layer

Ammonia is a promising fuel for protonic ceramic fuel cells (PCFCs), because of the high content of hydrogen and the advantages of safety and carbon neutrality. However, the wide application of PCFCs on ammonia fuel is greatly hindered by the relatively low electrochemical activity and durability. Here, we report a high-performance ammonia-fueled PCFC with enhanced electrochemical activity and durability, achieved by depositing an internal catalyst layer of an iron-doped ceria oxide (Fe-CeOx). It is demonstrated that the internal layer with a Fe: Ce molar ratio of 6:4 provides the best power output and durability. For example, when applied on tubular single cells with a configuration of Ni-BZCYYb (Fe-CeOx) || BZCYYb || PBSCF, a typical peak power density of 1.06 W cm−2 can be achieved on ammonia at 700 °C. The improved performance and longer lifetime are attributed to the Fe-CeOx internal catalyst, which can not only prevent the agglomeration of the particles during operation but also protect the Fe from reacting with ammonia to form iron nitride.

Boosting Electrocatalytic CO 2 Reduction with Conjugated Bimetallic Co/Zn Polyphthalocyanine Frameworks

Boosting Electrocatalytic CO ₂ Reduction with Conjugated Bimetallic Co/Zn Polyphthalocyanine Frameworks

Sonochemical-Assisted Biogenic Synthesis of Theophrasite β-Ni(OH)2 Nanocluster Using Chia Seeds Extract: Characterization and Anticancer Activity.

Theophrasite β-Ni(OH)2 nanocluster were fabricated via the sonochemical-assisted biogenic method using chia seeds extract as a reducing and stabilizing agent. The optical and morphological feature of the synthesized nanocluster was characterized using UV-Vis, FTIR, FE-SEM-EDS, HR-TEM, DLS, XPS, and XRD analysis. According to FE-SEM and HR-TEM images of the synthesized materials, β-Ni(OH)2 nanocluster illustrates the hexagonal particle shape with an average size of 5.8 nm, while the EDS results confirm the high purity of the synthesized nanocluster. Moreover, the XRD pattern of the synthesized materials shows typical peaks that match the reference pattern of the Theophrasite form of β-Ni(OH)2 with a hexagonal crystal system. The XPS analysis illustrates that the prepared samples exhibit both Ni2+ and Ni3+ with the predominance of Ni2+ species. Additionally the in-vitro cytotoxic activity of β-Ni(OH)2 nanocluster is tested against the MCF7 cell lines (breast cancer cells). The MTT assay results proved that the synthesized β-Ni(OH)2 nanocluster has potent cytotoxic activity against breast cancer cell lines (IC50: 62.7 μg/mL).

Preparation of NiO/MWCNTs nanocomposite for the removal of cadmium ions

In this work, a portable nanocomposite film made from nickel oxide nanoparticles (NiO NPs), multi-walled carbon nanotubes (MWCNTs), and polyvinyl alcohol (PVA) was prepared and investigated for the removal of Cd (II) from an aqueous solution. The preparation was carried out by eco-friendly pulsed laser ablation in liquid environmental technique to synthesize NiO NPs and to decorate MWCNTs to form NiO NPs/MWCNTs nanocomposites, followed by the formation of a portable nanocomposite film from the interaction between PVA and NiO NPs/MWCNTs nanocomposite. After that, the physicochemical properties of the prepared samples were investigated by XRD, SEM, EDX, TGA, and FT-IR. From structural analysis, the matrix nanocomposite film showed the presence of the hexagonal structure plane of NiO, PVA, and graphite, and its elemental analysis has just C, O, and Ni, which represent the constituent elements of the PVA matrix, MWCNTs, and NiO NPs. From morphological analysis, NiO NPs were loaded on the outer surface of the tubular structure of MWCNTs in a spherical shape. From optical analysis, the typical transmittance peaks of Ni–O–C and Ni–O were appeared. Also, the peaks related to the main functional groups of MWCNTs were shifted due to the interactions between MWCNTs and NiOs by non-covalent bonds. From thermal analysis, the thermal degradation is similar to that of pure PVA, but with higher percentage of decomposition due to presence of MWCNTs and NiO NPs. Furthermore, the effects of several parameters, such as pH, initial Cd (II) concentration, and adsorbent dosage, were studied in order to reach their maximum adsorption, representing the optimal conditions for the removal of Cd (II) from an aqueous solution. From these results, the adsorption of these heavy metal ions increased with pH and peaked at about pH 7–8. Also, their percentages of adsorption increased as the weight of the adsorbent dosage was raised. Based on these findings, it can be inferred that the produced nanocomposite might be an effective adsorbent for metal ions in aqueous solutions. So, these results showed the capability of using NiO NPs/MWCNTs/PVA nanocomposite film in a water treatment process and that it might be utilized to purify water before it is released into the natural environment.

Elastic scattering investigation of radioactive B13 and O13 projectiles on a Pb208 target at intermediate energies

Elastic scattering measurements were performed for the proton drip-line nucleus $^{13}\mathrm{O}$ (with ${S}_{p}=1.512$ MeV) and its partner mirror nucleus $^{13}\mathrm{B}$ (with ${S}_{n}=4.878$ MeV) projectiles on a $^{208}\mathrm{Pb}$ target at intermediate energies, namely ${E}_{\mathrm{lab}}=413$ and 254 MeV, respectively. These secondary radioactive ion beams were produced at the Radioactive Ion Beam Line in Lanzhou (RIBLL), Heavy-Ion Research Facility in Lanzhou (HIRFL). The elastic scattering angular distributions for these projectiles show a typical Fresnel diffraction peak at forward angles. Optical model analyses of the angular distributions, using double-folding and global potentials, were performed and different densities for these projectiles were probed.

Detachable all-carbon-linked 3D covalent organic framework films for semiconductor/COF heterojunctions by continuous flow synthesis

Detachable all-carbon-linked 3D covalent organic framework films for semiconductor/COF heterojunctions by continuous flow synthesis

Pd/Ni-Al hydrotalcite for base-free alcohol oxidation: Dependency of activity and selectivity on palladium precursors and reduction reagents

Benzyl alcohol was chosen as a model substrate for Pd/hydrotalcite mediated selective oxidation of alcohols to investigate the roles of palladium precursors (Na2PdCl4, K2PdCl4, PdCl2), reduction reagents (N2H4 and NaBH4), and Pd loading amount in determining structure-activity relationship of flower-like nano-catalyst. XRD analyses show typical characteristic peaks of all hydrotalcites regardless of palladium precursors; whereas TEM studies show a larger mean size of Pd nanoparticles obtained with reducing reagent N2H4 over NaBH4. However, the difference in particle sizes didn't result in a significant difference in benzyl alcohol conversion, but extended to catalytic selectivity where N2H4-reduced Pd/hydrotalcite achieved 94%-96% selectivity over 88%-93% by NaBH4. FTIR-CD3CN surface acidity study suggested that a stronger acidity of N2H4 reduced Pd/hydrotalcite may account for its better selectivity. 3% Pd/hydrotalcite with N2H4 as reducing reagent demonstrated the best catalytic performance; and was successfully extended to oxidation of 17 aromatic and aliphatic alcohols. The conversion of alcohols is strongly dependent on individual alcohol molecular structure and electronic effect; but all reactions showed medium-to-excellent selectivity.

Characterization and biological evaluation of phenazine produced by antagonistic pseudomonads against Fusarium oxysporum f. sp. ciceris

Analysis of phenazine for fifteen pigment-producing Fusarium oxysporum f. sp. ciceris (Foc) antagonistic rhizobactria, ranged between 20.5 and 706.4 μg/mL, with the maximum production recorded by the isolate Ps45. Similarly, isolate Ps45 exhibited the highest values of phenazine-1-carboxylic acid (PCA) and 2-hydroxy-phenazine carboxylic acid (2-OH-PCA) concentration (268.1 and 44.4 μg/mL, respectively), whereas isolate Ps44 exhibited the highest hydroxy phenazine-dioxide (OH-P-dioxide) or iodinin concentration (621.2 μg/mL). In 10 pseudomonads, phz CD genes were marked for their capability to synthesize PCA. Thin layer chromatography (TLC) and high-performance liquid chromatography (HPLC) of five potential phenazines producers showed coloured spots with the same mobility and Rf value with the standard phenazine and a typical peak maxima at 247 nm. The highest phenazine concentration (612.1 μg/mL) was recorded by isolate Ps44. Scanning electron microscopic(SEM) evaluation of the crude phenazine extract of potential isolates disclosed disrupting and dwindling effects on the hyphal growth of selected virulent strain of Foc hyphal growth.

Effect of different vent covers on the overpressure and flame propagation characteristics of hydrocarbon fuel-air mixture venting explosion

A series of hydrocarbon-air fuel venting explosion experiments were carried out in a 20-L small-scale vent tank, and the effect of four different vent covers with an inherent rupture pressure of 10 kPa on the overpressures and flame propagation characteristics was studied. The results of the experiments showed that all the internal and external overpressure-time profiles have five typical overpressure peaks, induced by burst of the vent cover (△p1), inertia effect (△pneg), burned gas releasing (△p2), external explosion (△p3) and Helmholtz oscillation (△phel), respectively. The dynamic process of the flame was basically tally with the rule of ‘smooth and hemispherical flame-twisted and stretched flame-mushroom cloud-like/ellipsoidal flame-extinguishing flame’, but some differences were still existed due to the specific damage mode of each vent cover. When the vent opening was sealed by different vent covers, the values of internal and external overpressure peaks, maximum rate of overpressure rises, flame front location along different directions, and flame front speed along different directions showed various trends. Specifically, the enhancement effect of the metal cover plate and PE vent cover was significantly weaker than that of the paper vent cover and Al vent cover for the overpressure and vertical flame parameters, while, the enhancement effect of the metal cover plate was found to be greater than the other three for the horizontal flame parameters. Consequently, PE cover had the optimum performance for the explosion venting under the same inherent rupture pressures. These results improve our understanding on gas explosion dynamics in a semi-confined space with a vent cover, and provides the overpressure and flame characteristics of gas venting explosion under different vent boundary conditions from the qualitative and quantitative view.

Facile biomimetic synthesis of AgNPs using aqueous extract of Helichrysum arenarium: characterization and antimicrobial activity

The present study focuses on synthesis of silver nanoparticles (AgNPs) by employment of a green and facile synthesis method. Aqueous extract of Helichrysum arenarium was used as a reducing and capping agent. The bioreduction of silver particles was monitored using UV–Vis spectroscopy based on increase in color intensity led by surface plasmon resonance. SEM, TEM, FTIR, DSC, and XRD analyses were followed for characterization, divulging that the nanoparticles were thermally resistant in the size of approximately 20 nm with a quasi-spherical shape without any agglomeration. AgNPs possessed a nanocrystal form with presence of crystalline Ag. EDAX analysis was used to verify that the nanoparticles were silver as revealed by a typical optical absorption peak of metallic silver nanocrystallites. The AgNPs were shown to have strong antibacterial and antifungal effects on some foodborne pathogens. The method developed in this study could offer a green, facile biomimetic, and cost-effective method.

Synthesis of Silver Nanoparticles Using Premna serratifolia Linn. Leaf Extract as Reducing Agent and Their Antibacterial Activity

Premna serratifolia Linn. leaf extract has been used as a reducing agent in the synthesis of silver nanoparticles (AgNPs). Various synthesis parameters such as reaction time, concentration and the pH of the Premna serratifolia Linn. leaf extract, and silver nitrate concentration were investigated. In addition, the stability of synthesized AgNPs and their activity against Staphylococcus aureus and Escherichia coli have also been investigated. The results of the experiment showed that Premna serratifolia Linn. leaf extract reduced silver ions resulting in AgNPs. In addition, the AgNPs colloid showed a gradual change in color from transparent green to yellow. At the same time, its ultraviolet (UV)-Visible spectra exhibited the typical surface plasmon resonance peak at around 400-415 nm. The optimum reaction conditions in the formation of AgNPs are 40 minutes of reaction time using silver nitrate 1.5x10-4 M and Premna serratifolia Linn leaf extract 80 ppm at pH 10. The particle size of synthesized AgNPs distributes from 48.3-157 nm with an average size of 58.7±14.4 nm and is stable at least for 1- month storage under ambient conditions. The antibacterial test shows that synthesized AgNPs are effective against both Escherichia coli and Staphylococcus aureus.

Cholera Outbreaks in India, 2011-2020: A Systematic Review.

Fecal contamination of water sources and open defecation have been linked to cholera outbreaks in India. However, a systematic review on the drivers responsible for these outbreaks has yet to be published. Here, we systematically review the published literature on cholera outbreaks in India between 2011 and 2020. We searched studies in English in three databases (MEDLINE, EMBASE, and Web of Science) and the Integrated Disease Surveillance Program that tracks cholera outbreaks throughout India. Two authors independently extracted data and assessed the quality of the included studies. Quantitative data on the modes of transmission reviewed in this study were assessed for any change over time between 2011–2015 and 2016–2020. Our search retrieved 10823 records initially, out of which 81 full-text studies were assessed for eligibility. Among these 81 studies, 20 were eligible for inclusion in this review. There were 565 reported outbreaks between 2011 and 2020 that led to 45,759 cases and 263 deaths. Outbreaks occurred throughout the year; however, they exploded with monsoons (June through September). In Tamil Nadu, a typical peak of cholera outbreaks was observed from December to January. Seventy-two percent (33,089/45,759) of outbreak-related cases were reported in five states, namely Maharashtra, West Bengal, Punjab, Karnataka, and Madhya Pradesh. Analysis of these outbreaks highlighted the main drivers of cholera including contaminated drinking water and food, inadequate sanitation and hygiene (including open defecation), and direct contact between households. The comparison between 2011–2015 and 2016–2020 showed a decreasing trend in the outbreaks that arose due to damaged water pipelines. Many Indians still struggle with open defecation, sanitation, and clean water access. These issues should be addressed critically. In addition, it is essential to interrupt cholera short-cycle transmission (mediated by households, stored drinking water and foodstuffs) during an outbreak. As cholera is associated with deprivation, socio-economic development is the only long-term solution.

Development and in-vitro characterization of HAP blended PVA/PEG bio-membrane

Hydroxyapatite HAP is a bioceramic that can be applied for bone tissue regeneration. Polyvinyl Alcohol (PVA)/Polyethylene Glycol (PEG) polymers are water-soluble and have faster biodegradation properties. The PVA-PEG-HAp thin membrane was cast by using the transparent solution petri-dish method. The PVA-PEG-HAp thin membrane was investigated by Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Energy Dispersive X-Ray Analysis (EDX), and Field Emission Scanning Electron Microscope (FESEM. Both PVA and HAp of membrane matrix had typical peaks at 2Ɵ value 19.78. PEG also has a distinctive peak at 26.687. The five (5, 25, 50, 75, and 10 μl) different concentrations of extracts of PVA-PEG-HAp thin membrane were pertinent to interacting for 24 h with the L929 mouse cell line, and the results were exhibited a maximum of 99% and 93% cell viability, 1% and 7% cytotoxicity, respectively. Hence the newly developed polymer biomembrane is a biocompatible alternative for biofilms in medical applications.

Effect of KOH concentration on the properties of ZnO nanoparticles

Of late, ZnO nanoparticles have been regarded as favourable material for designing highly sensitive and selective gas sensors owing to their striking and multifunctional features. A facile sol–gel process chemical technique was used in this study for the preparation of undoped ZnO nanoparticles. By deploying x-ray diffraction (XRD), transmission electron microscopy (TEM), UV–visible near infrared and photoluminescence spectroscopy (PL), we examined the optical attributes and structural characterisation of the undoped ZnO nanoparticles through a change in the concentration of the KOH solution. The typical peaks inspected in the XRD spectrum corroborate the wurtzite hexagonal arrangement in the undoped ZnO nanoparticles. Moreover, ZnO nanoparticles possess a non-agglomerated crystalline with spherical morphology, as acquired by TEM. In addition, the vibrational modes in FTIR spectra vary with the change of concentration of KOH solution in ZnO NPs. The Raman spectroscopic techniques were used to characterise the ZnO nanoparticles, which revealed their nanocrystalline nature.

Meteorological aspects of the atypical seasonal lightning distribution at the Gaisberg tower

The seasonal lightning distribution at the Gaisberg tower in Austria is very different from the distribution observed in a circular ring with a radius of 2 to 10 km around the tower. The distribution in the circular ring shows the typical peak during the convective season. In contrast, we find a bimodal distribution with a peak in early spring and late fall at the tower. By selecting two cases representing these two situations, the differences in the meteorological setting are discussed.Lightning events observed solely at the Gaisberg tower are characterized by strong horizontal winds in the lower layers of the atmosphere from the northwest sector. This direction represents the open window from the Gaisberg towards the foreland, meaning there are no mountains upstream, and the flow can reach the Gaisberg unhindered. Cases of this type occur mainly during the cold season but are not limited to it.In contrast, lightning events at the tower and in its vicinity are typical for convective events with low horizontal wind speed in the lower layers and occur mainly during the convective season.

Global fallout Pu isotopes, 137Cs and 237Np records in the sediments of Lake Xingkai and their response to environmental changes in the catchment

Plutonium (Pu) isotopes, neptunium-237 (237Np) and cesium-137 (137Cs) in the environment have emerged as important tools for promoting geochemical studies. To elucidate their source terms, deposition process, and the geochemical behavior, as well as their response to catchment environmental changes in lacustrine environment, 239, 240Pu, 137Cs and 237Np were determined for the first time in a sediment core collected from the Lake Xingkai. The 240Pu/239Pu atom ratios (0.163–0.178) in all sediment samples corresponded well with the typical global fallout value of ∼0.18, indicating that there were no other significant radioactive source inputs. The activity concentrations of 239+240Pu, 137Cs, and 237Np were 0.010–1.030 Bq kg−1, 6.4–30.1 Bq kg−1, and (0.020–2.195) × 10−3 Bq kg−1, respectively. They presented similar vertical distribution patterns, with a typical global fallout peak (15–16 cm) corresponding to the year of 1964. On the other hand, the 237Np/239Pu atom ratios exhibited a wide range (0.207–1.306), and showed a trend of increasing values with depth, implying different geochemical behaviors of these two elements. Using the advection-dispersion equation model (ADE), the obtained apparent dispersion coefficient of 237Np (0.58 ± 0.09 cm2 yr−1) was higher than that of 239+240Pu (0.38 ± 0.07 cm2 yr−1), indicating that Np has greater mobility than Pu. The total global fallout inventories of 239+240Pu, 137Cs, and 237Np were 145, 4592, and 0.291 Bq m−2, respectively. Approximately 46% of the total global fallout was derived from riverine input, indicating that severe soil erosion occurred in the catchment of Lake Xingkai in the past decades.

Removal of Remazol Yellow Using SnO2-Co Photocatalyst

Remazol yellow is a synthetic dye that pollutes the environment and causes disease because it is carcinogenic and mutagenic. Photocatalyst is one of the technologies to remove the dye concentration, and tin oxide (SnO2) with cobalt (Co) dopant has the potential to be a good semiconductor in the process. Therefore, this study aims to synthesize SnO2/Co composites as a photocatalyst to degrade Remazol yellow dye. The photodegradation process was carried out with several variables, including the effect of time and the initial concentration of the dye and conditions under pHpzc. Furthermore, the composites were made with SnO to Co mass ratios of (2:1), (2:2), (2:3), and were characterized using X-Ray Diffraction (XRD), Scanning Electron Microscope-Energy Dispersive X-Ray (SEM-EDX), and Ultraviolet-Visible Diffuse Reflectance Spectroscopy (UV-Vis DRS) instruments. Based on the results, the SnO2/Co (2:3) composite was selected as a photocatalyst to degrade the dye as the XRD characterization showed the formation of a typical peak of 2θ at 33o. The energy bandgap of SnO2 is 3.05 eV, while the (2:3) composite had a value of 2.8eV. Moreover, the SEM characterization showed a non-uniform surface with pores and elements composition of Sn, O, and Co with the values 61.24, 24.67, and 14.09 wt%, respectively. The optimum condition for photodegradation was obtained at a contact time and concentration of 180 minutes and 10 ppm, respectively, while the removal of the dye reached 65-80%.

Esterification of Acetin Production from By-Products of Biodiesel Industry Using Heterogeneous Catalysts Based on Wetland Commodities

The peculiarities of wetland commodities are unique and can produce new materials which function as catalysts. The objective was to determine the best catalyst components, crystalline properties, pore size, catalyst morphology, and selectivity in producing acetin. The research started with sampling, sorting, purification, extraction, catalyst synthesis, characterization, and determining the molar ratio between glycerol sourced from biodiesel industry by-products and CH3COOH. Determination of catalyst components by XRF spectrometry, crystallinity by XRD, pore size by Brunauer-Emmett-Teller, and morphology of the resulting catalyst used SEM/EDS. Selectivity of the target compound in the form of acetin, either monoacetin, diacetin, or triacetin, used GC-MS. The catalyst of orange peels obtained silica 29.201% and alumina 4.115%, pineapple leaves obtained silica 34.072% and alumina 0.074%, and sugar palm peels obtained silica 40.017% and alumina 0.953%. The diffractogram results showed that all heterogeneous catalysts had sharp-narrow peaks, meaning the crystallinity of the sample was high according to the typical peak of SiO2. The pore size of the orange peel catalyst was 4.328 nm with a surface area of 263.475 m2 g-1, the pineapple leaf catalyst was 4.850 nm and 35.983 m2 g-1, and the sugar palm peel catalyst was 5.658 nm and 10.884 m2 g-1. The results of the morphological test of orange peels were composed of a very heterogeneous dense porous structure; pineapple leaves were amorphous, while sugar palm peels were composed of small, irregular pores. All the resulting heterogeneous catalysts met the characteristics of standard SiO2 silica catalysts. The best acetin selectivity result is a 1:9 molar ratio.