At depth in an abandoned tunnel of the White Pine Copper Mine, green films of the Cu-OH-Cl minerals atacamite and paratacamite were found on standing pools of brine. Some pools were also coated with a thin layer of petroleum. Green films of atacamite were composed of individual blebs that averaged 20 μm in diameter and enclosed mixed colonies of Gram-negative, short rod-shaped, and sheathed filamentous bacteria. Carbon δ13C values in the atacamite–paratacamite mixtures reflect the isotopic values of bacteria and minor amounts of petroleum mixed with the minerals. Heterotrophic bacteria are interpreted to be using petroleum as a carbon source and may be catalyzing the precipitation of the copper hydroxy chloride minerals or acting as a template.
{"title":"Geochemistry and Microbiology of Atacamite-Paratacamite Biofilms Floating on Underground Brine and Petroleum Pools in the White Pine Copper Mine, Michigan (USA)","authors":"E. Robbins, M. R. Stanton, Cheryl D. Young","doi":"10.3390/micro3030051","DOIUrl":"https://doi.org/10.3390/micro3030051","url":null,"abstract":"At depth in an abandoned tunnel of the White Pine Copper Mine, green films of the Cu-OH-Cl minerals atacamite and paratacamite were found on standing pools of brine. Some pools were also coated with a thin layer of petroleum. Green films of atacamite were composed of individual blebs that averaged 20 μm in diameter and enclosed mixed colonies of Gram-negative, short rod-shaped, and sheathed filamentous bacteria. Carbon δ13C values in the atacamite–paratacamite mixtures reflect the isotopic values of bacteria and minor amounts of petroleum mixed with the minerals. Heterotrophic bacteria are interpreted to be using petroleum as a carbon source and may be catalyzing the precipitation of the copper hydroxy chloride minerals or acting as a template.","PeriodicalId":18398,"journal":{"name":"Micro & Nano Letters","volume":"28 1","pages":""},"PeriodicalIF":1.3,"publicationDate":"2023-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88269202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study focuses on the wear effects of nano-sized titania as a potential engine lubricant additive. Titanium dioxide nanoparticles have promising wear-reducing properties and significant tribological potential. In this article, titania nanoparticles were homogenized in Group III automotive oil at five different concentrations (0.1; 0.2 … 0.5 wt%). The nanodoped oil samples were tested on a linear oscillating tribometer with oil circulation. Based on the tribological results, titania nanoparticles increased friction by 20–32% but can reduce the wear area by up to 32%. According to the confocal microscopic examination, wear volume can be reduced by up to 57% with titania nanoparticles. Titania nanoparticles improved the repeatability of tribological measurements. A scanning electron microscopy examination of the wear track revealed that the characteristic wear of the tribological system was abrasive, but a significant amount of adhesive wear was also observed. Energy dispersive X-ray spectroscopy analysis found that the nanoparticles fill the deeper trenches of the wear. The worn surface uniformly contains TiO2 particles and the quantified normalized titanium concentration was between 0.56 and 0.62%.
{"title":"Experimental Wear Analysis of Nano-Sized Titania Particles as Additives in Automotive Lubricants","authors":"Á. Szabó, Á. Tóth, Hebah Abdallah, H. Hargitai","doi":"10.3390/micro3030050","DOIUrl":"https://doi.org/10.3390/micro3030050","url":null,"abstract":"This study focuses on the wear effects of nano-sized titania as a potential engine lubricant additive. Titanium dioxide nanoparticles have promising wear-reducing properties and significant tribological potential. In this article, titania nanoparticles were homogenized in Group III automotive oil at five different concentrations (0.1; 0.2 … 0.5 wt%). The nanodoped oil samples were tested on a linear oscillating tribometer with oil circulation. Based on the tribological results, titania nanoparticles increased friction by 20–32% but can reduce the wear area by up to 32%. According to the confocal microscopic examination, wear volume can be reduced by up to 57% with titania nanoparticles. Titania nanoparticles improved the repeatability of tribological measurements. A scanning electron microscopy examination of the wear track revealed that the characteristic wear of the tribological system was abrasive, but a significant amount of adhesive wear was also observed. Energy dispersive X-ray spectroscopy analysis found that the nanoparticles fill the deeper trenches of the wear. The worn surface uniformly contains TiO2 particles and the quantified normalized titanium concentration was between 0.56 and 0.62%.","PeriodicalId":18398,"journal":{"name":"Micro & Nano Letters","volume":"76 1","pages":""},"PeriodicalIF":1.3,"publicationDate":"2023-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81240367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The composites Au/SiO2, Au/TiO2, Au/Al2O3, ZnO/TiO2, ZnO/TiO2, ZnO/Al2O3 and Eu2O3/SiO2, Eu2O3/TiO2 and Eu2O3/Al2O3 were prepared using a solid-state method. The effect of the polymer precursors was investigated using two precursor polymers, Chitosan and Poly(styrene-co-4vinylpyridine), (PS-co-4-PVP) in the M/MxLy•Chitosan//M’xO’y as well as M/MxLy•PS-co-4-PVP//M’xO’y with M’xO’y = SiO2, TiO2 and Al2O3. The effects on the particle size and morphology were observed. The new composites were characterized using X-ray powder diffraction, SEM-EDS mapping and HRTEM analysis. The distribution of the metallic nanoparticles as well as the metal oxide nanoparticles inside the matrices depend on the matrix. Marked optical and photocatalytic effects of the Au, ZnO and Eu2O3 inside the SiO2, TiO2 and Al2O3 matrices are expected. An experiment is in course.
{"title":"Matrix Effect of Properties of Au, ZnO and Eu2O3: Silica, Titania and Alumina Matrices","authors":"Carlos Díaz, O. Cifuentes-Vaca, M. Valenzuela","doi":"10.3390/micro3030049","DOIUrl":"https://doi.org/10.3390/micro3030049","url":null,"abstract":"The composites Au/SiO2, Au/TiO2, Au/Al2O3, ZnO/TiO2, ZnO/TiO2, ZnO/Al2O3 and Eu2O3/SiO2, Eu2O3/TiO2 and Eu2O3/Al2O3 were prepared using a solid-state method. The effect of the polymer precursors was investigated using two precursor polymers, Chitosan and Poly(styrene-co-4vinylpyridine), (PS-co-4-PVP) in the M/MxLy•Chitosan//M’xO’y as well as M/MxLy•PS-co-4-PVP//M’xO’y with M’xO’y = SiO2, TiO2 and Al2O3. The effects on the particle size and morphology were observed. The new composites were characterized using X-ray powder diffraction, SEM-EDS mapping and HRTEM analysis. The distribution of the metallic nanoparticles as well as the metal oxide nanoparticles inside the matrices depend on the matrix. Marked optical and photocatalytic effects of the Au, ZnO and Eu2O3 inside the SiO2, TiO2 and Al2O3 matrices are expected. An experiment is in course.","PeriodicalId":18398,"journal":{"name":"Micro & Nano Letters","volume":"142 1","pages":""},"PeriodicalIF":1.3,"publicationDate":"2023-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88557185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, the electrochemical non-enzymatic detection of Riboflavin (RF) was proposed based on its catalytic reduction in a Thionine-coated Cadmium Selenide Quantum dots (TH@CdSe QDs)-modified paraffin wax-impregnated graphite electrode (PIGE) that was prepared using a novel approach. The synthesized TH@CdSe QDs were confirmed by UV-Vis spectroscopy, Confocal Raman Microscopy and High Resolution Transmission Electron Microscopy (HRTEM) studies. The electrochemical response of the TH@CdSe QDs-modified PIGE was studied by cyclic voltammetry. The voltammetric response of RF at the TH@CdSe QDs-modified PIGE showed higher current than the bare PIGE. Under optimum conditions, the electrocatalytic reduction currents of RF was found to be linearly related to its concentration over the range of 1.6 × 10−7 M to 1.4 × 10−4 M with a detection limit of 53 × 10−9 M (S/N = 3). The TH@CdSe QDs-modified PIGE was utilized as an amperometric sensor for the detection of RF in flow systems was performed by carrying out hydrodynamic and chronoamperometric experiments. The TH@CdSe QDs-modified PIGE showed very good stability and a longer shelf life. The applicability of the fabricated electrode was justified by the quantification of RF in commercial tablets.
本文提出了一种新的方法，利用巯基包覆硒化镉量子点(TH@CdSe QDs)修饰石蜡浸渍石墨电极(PIGE)催化还原核黄素(RF)的电化学非酶检测方法。通过紫外可见光谱、共聚焦拉曼显微镜和高分辨率透射电子显微镜(HRTEM)对合成的TH@CdSe量子点进行了验证。采用循环伏安法研究了TH@CdSe qds修饰的PIGE的电化学响应。RF在TH@CdSe qds修饰的PIGE处的伏安响应显示出比裸PIGE更高的电流。在最佳条件下，RF的电催化还原电流与其浓度在1.6 × 10−7 M ~ 1.4 × 10−4 M范围内呈线性关系，检出限为53 × 10−9 M (S/N = 3)。利用TH@CdSe qds改进的PIGE作为电流传感器，通过流体动力学和计时电流实验对流动系统中的RF进行了检测。TH@CdSe qds修饰的PIGE具有很好的稳定性和较长的保质期。通过对市售片剂中RF的定量分析，验证了所制备电极的适用性。
{"title":"Highly Sensitive Sensor for the Determination of Riboflavin Using Thionine Coated Cadmium Selenide Quantum Dots Modified Graphite Electrode","authors":"A. Kalaivani, R. Suresh Babu, S. Sriman Narayanan","doi":"10.3390/micro3030048","DOIUrl":"https://doi.org/10.3390/micro3030048","url":null,"abstract":"In this paper, the electrochemical non-enzymatic detection of Riboflavin (RF) was proposed based on its catalytic reduction in a Thionine-coated Cadmium Selenide Quantum dots (TH@CdSe QDs)-modified paraffin wax-impregnated graphite electrode (PIGE) that was prepared using a novel approach. The synthesized TH@CdSe QDs were confirmed by UV-Vis spectroscopy, Confocal Raman Microscopy and High Resolution Transmission Electron Microscopy (HRTEM) studies. The electrochemical response of the TH@CdSe QDs-modified PIGE was studied by cyclic voltammetry. The voltammetric response of RF at the TH@CdSe QDs-modified PIGE showed higher current than the bare PIGE. Under optimum conditions, the electrocatalytic reduction currents of RF was found to be linearly related to its concentration over the range of 1.6 × 10−7 M to 1.4 × 10−4 M with a detection limit of 53 × 10−9 M (S/N = 3). The TH@CdSe QDs-modified PIGE was utilized as an amperometric sensor for the detection of RF in flow systems was performed by carrying out hydrodynamic and chronoamperometric experiments. The TH@CdSe QDs-modified PIGE showed very good stability and a longer shelf life. The applicability of the fabricated electrode was justified by the quantification of RF in commercial tablets.","PeriodicalId":18398,"journal":{"name":"Micro & Nano Letters","volume":"48 1","pages":""},"PeriodicalIF":1.3,"publicationDate":"2023-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80626316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The foundation of drug delivery systems based on titanium dioxide nanotube arrays has become an important means to increase the drug release performance of bone implantation materials. However, most of the conventional platforms have some disadvantages, such as large sudden release, uncontrollable, unintelligent, or not on-demand drug release process. Herein, the authors develop a unique self-triggering drug release system (SDDS), utilizing the advantages of 1-Tetradecanol (TD), such as decent biocompatibility, a phase transition temperature of 37.8°C, and the inexistence of complex chemical reaction process. The establishment of the platform can make a large amount of the anti-inflammatory drug (ibuprofen, IBU) released when the body or the affected area is inflamed, that is, when the temperature rises. Conversely, only a small amount or no drug is released when there is no inflammation, thereby achieving self-trigger release and on-demand release. The experimental results show that the system combines good self-trigger release properties, release sensitivity, drug release cycle, and low selectivity to the loaded drugs.
{"title":"Self-trigger and on-demand drug delivery system based on TiO2 nanotube arrays and its drug release behaviour","authors":"Tao Zhang, Nannan Liu, Chunling Xie, Xiufeng Xiao","doi":"10.1049/mna2.12173","DOIUrl":"https://doi.org/10.1049/mna2.12173","url":null,"abstract":"<p>The foundation of drug delivery systems based on titanium dioxide nanotube arrays has become an important means to increase the drug release performance of bone implantation materials. However, most of the conventional platforms have some disadvantages, such as large sudden release, uncontrollable, unintelligent, or not on-demand drug release process. Herein, the authors develop a unique self-triggering drug release system (SDDS), utilizing the advantages of 1-Tetradecanol (TD), such as decent biocompatibility, a phase transition temperature of 37.8°C, and the inexistence of complex chemical reaction process. The establishment of the platform can make a large amount of the anti-inflammatory drug (ibuprofen, IBU) released when the body or the affected area is inflamed, that is, when the temperature rises. Conversely, only a small amount or no drug is released when there is no inflammation, thereby achieving self-trigger release and on-demand release. The experimental results show that the system combines good self-trigger release properties, release sensitivity, drug release cycle, and low selectivity to the loaded drugs.</p>","PeriodicalId":18398,"journal":{"name":"Micro & Nano Letters","volume":"18 8","pages":""},"PeriodicalIF":1.3,"publicationDate":"2023-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/mna2.12173","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50128492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alexander Wiede, O. Stranik, A. Tannert, U. Neugebauer
Recent developments in the field of additive manufacturing processes have led to tremendous technological progress and opened directions for the field of microfluidics. For instance, new flexible materials for 3D printing allow the substitution of polydimethylsiloxane (PDMS) in microfluidic prototype development. Three-dimensional-printed microfluidic components open new horizons, in particular for the automated handling of biological cells (e.g., eukaryotic cells or bacteria). Here, we demonstrate how passive mixing and passive separation processes of biological cells can be realized using 3D printing concepts for rapid prototyping. This technique facilitates low-cost experimental setups that are easy to modify and adopt for specific detection and diagnostic purposes. In particular, printing technologies based on fused deposition modeling and stereolithography are used and their realization is discussed. Additive technologies enable the fabrication of multiplication mixers, which overcome shortcomings of current pillar or curve-based techniques and enable efficient mixing, also of biological cells without affecting viability. Using standard microfluidic components and state-of-the art 3D printing technologies, we realize a separation system based on Dean flow fragmentation without the use of PDMS. In particular, we describe the use of a 3D-printed helix for winding a capillary for particle flow and a new chip design for particle separation at the outlet. We demonstrate the functionality of the system by successful isolation of ~12 µm-sized particles from a particle mixture containing large (~12 µm, typical size of eukaryotic cells) and small (~2 µm, typical size of bacteria or small yeasts) particles. Using this setup to separate eukaryotic cells from bacteria, we could prove that cell viability is not affected by passage through the microfluidic systems.
{"title":"Microfluidic System for Cell Mixing and Particle Focusing Using Dean Flow Fractionation","authors":"Alexander Wiede, O. Stranik, A. Tannert, U. Neugebauer","doi":"10.3390/micro3030047","DOIUrl":"https://doi.org/10.3390/micro3030047","url":null,"abstract":"Recent developments in the field of additive manufacturing processes have led to tremendous technological progress and opened directions for the field of microfluidics. For instance, new flexible materials for 3D printing allow the substitution of polydimethylsiloxane (PDMS) in microfluidic prototype development. Three-dimensional-printed microfluidic components open new horizons, in particular for the automated handling of biological cells (e.g., eukaryotic cells or bacteria). Here, we demonstrate how passive mixing and passive separation processes of biological cells can be realized using 3D printing concepts for rapid prototyping. This technique facilitates low-cost experimental setups that are easy to modify and adopt for specific detection and diagnostic purposes. In particular, printing technologies based on fused deposition modeling and stereolithography are used and their realization is discussed. Additive technologies enable the fabrication of multiplication mixers, which overcome shortcomings of current pillar or curve-based techniques and enable efficient mixing, also of biological cells without affecting viability. Using standard microfluidic components and state-of-the art 3D printing technologies, we realize a separation system based on Dean flow fragmentation without the use of PDMS. In particular, we describe the use of a 3D-printed helix for winding a capillary for particle flow and a new chip design for particle separation at the outlet. We demonstrate the functionality of the system by successful isolation of ~12 µm-sized particles from a particle mixture containing large (~12 µm, typical size of eukaryotic cells) and small (~2 µm, typical size of bacteria or small yeasts) particles. Using this setup to separate eukaryotic cells from bacteria, we could prove that cell viability is not affected by passage through the microfluidic systems.","PeriodicalId":18398,"journal":{"name":"Micro & Nano Letters","volume":"282 1","pages":""},"PeriodicalIF":1.3,"publicationDate":"2023-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76255450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Bailón-Ruiz, Y. Cedeño-Mattei, K. Torres-Torres, L. Alamo-Nole
Azo dyes such as Tropaeolin O have diverse applications in the textile, food, and biomedical industries. However, their recalcitrant properties make them toxic substances in surface waters. Nanocatalysts are photoactive nanoparticles that generate reactive oxygen species to destroy organic compounds. Moreover, the presence of dopant agents in the nanoparticles’ crystalline structure efficiently enhances photocatalytic activity. Ag-doped ZnO nanoparticles were prepared in ethylene glycol at 197 °C and characterized by UV-Vis absorption, photoluminescence, high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), and electron diffraction (ED). The particles were mainly spherical with a size of ~10 nm, a hexagonal structure, and an elemental composition of 56.2% Zn, 37.8% O, and 5.9% Ag. The particles evidenced a broad absorption peak in the UV region and two emission peaks. Absorption analysis indicates that 92% and 58% of Tropaeolin O were degraded using 100 and 50 ppm of Ag-doped ZnO nanoparticles, respectively, during the first 550 min. Ion chromatograms selected using quadrupole time-of-flight liquid chromatography-mass spectrometry (QTOF-LC-MS) indicate a complete Tropaeolin O degradation (295.04 m/z) during the first 330 min. Initially, the nanocatalyst attacks the electron-rich groups (-OH and -NH), generating the 277.03 m/z [M-OH]+ and 174.02 m/z (molecule rupture on the azo group). In addition, small oxidized fragments 167.03 m/z and 114.03 m/z confirm the nanoparticles’ photocatalytic capacity, and oxidized chains indicate the tropaeolin’s opening rings (including phtalic acids) and mineralization.
{"title":"Photodegradation of Tropaeolin O in the Presence of Ag-Doped ZnO Nanoparticles","authors":"S. Bailón-Ruiz, Y. Cedeño-Mattei, K. Torres-Torres, L. Alamo-Nole","doi":"10.3390/micro3030045","DOIUrl":"https://doi.org/10.3390/micro3030045","url":null,"abstract":"Azo dyes such as Tropaeolin O have diverse applications in the textile, food, and biomedical industries. However, their recalcitrant properties make them toxic substances in surface waters. Nanocatalysts are photoactive nanoparticles that generate reactive oxygen species to destroy organic compounds. Moreover, the presence of dopant agents in the nanoparticles’ crystalline structure efficiently enhances photocatalytic activity. Ag-doped ZnO nanoparticles were prepared in ethylene glycol at 197 °C and characterized by UV-Vis absorption, photoluminescence, high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), and electron diffraction (ED). The particles were mainly spherical with a size of ~10 nm, a hexagonal structure, and an elemental composition of 56.2% Zn, 37.8% O, and 5.9% Ag. The particles evidenced a broad absorption peak in the UV region and two emission peaks. Absorption analysis indicates that 92% and 58% of Tropaeolin O were degraded using 100 and 50 ppm of Ag-doped ZnO nanoparticles, respectively, during the first 550 min. Ion chromatograms selected using quadrupole time-of-flight liquid chromatography-mass spectrometry (QTOF-LC-MS) indicate a complete Tropaeolin O degradation (295.04 m/z) during the first 330 min. Initially, the nanocatalyst attacks the electron-rich groups (-OH and -NH), generating the 277.03 m/z [M-OH]+ and 174.02 m/z (molecule rupture on the azo group). In addition, small oxidized fragments 167.03 m/z and 114.03 m/z confirm the nanoparticles’ photocatalytic capacity, and oxidized chains indicate the tropaeolin’s opening rings (including phtalic acids) and mineralization.","PeriodicalId":18398,"journal":{"name":"Micro & Nano Letters","volume":"12 1","pages":""},"PeriodicalIF":1.3,"publicationDate":"2023-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82200413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Rocha, B. D. A. Feitosa, A. S. Carolino, Ronald Zico de Aguiar Nunes, Célio Matias Airone Macalia, Kalil Araújo da Silva, Cleverton Oliveira Dias, S. M. de Souza, P. Campelo, J. Bezerra, E. Sanches
Microfibers are important to several areas of human lifestyle, and the knowledge about their physicochemical characteristics allows for proposing new technological applications. The in natura microfiber of Ochroma pyramidale fruit (IN sample) and its extracted pulp (PU sample) were evaluated by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetry and Differential Scanning Calorimetry (TG/dTG and DSC). Microfibers were composed mainly of (68 ± 1)% holocellulose, (35.8 ± 0.1)% cellulose, (32 ± 3)% lignin and (3.7 ± 0.3)% extractives. The XRD pattern of the PU sample revealed that the mercerization process resulted in the change of the cellulose crystal structure from Iα type (triclinic) to type II (monoclinic). The SEM technique showed that the IN sample presented regular cylindrical/hollow-shaped wire-like microfibers with diameters ranging from 5 µm to 25 µm. However, the mercerization process changed their natural morphology. A significant change in the FTIR spectra after the removal of hemicellulose and lignin components was observed: weak bands at 1739 cm−1 (C=O stretching of lignin and hemicellulose fractions), 1463 cm−1 (CH3 of lignin) and 1246 cm−1 (C-O of lignin) were still observed in the PU sample, indicating that the lignin was not completely removed due to the natural difficulty of isolating pure cellulose. The TG/dTG and DSC evaluation revealed a temperature increase of the second thermal event (starting at 235 °C) in the PU sample, which was assigned to the cellulose and residual hemicellulose degradation. Then, this work aimed to disseminate and characterize a microfiber with unusual characteristics still little explored by the scientific community, as well as its cellulosic pulp, providing information that may be useful in its application in different industries, enabling the positive development of new biocompatible, renewable and sustainable materials.
{"title":"Extraction and Modification of Cellulose Microfibers Derived from Biomass of the Amazon Ochroma pyramidale Fruit","authors":"A. Rocha, B. D. A. Feitosa, A. S. Carolino, Ronald Zico de Aguiar Nunes, Célio Matias Airone Macalia, Kalil Araújo da Silva, Cleverton Oliveira Dias, S. M. de Souza, P. Campelo, J. Bezerra, E. Sanches","doi":"10.3390/micro3030046","DOIUrl":"https://doi.org/10.3390/micro3030046","url":null,"abstract":"Microfibers are important to several areas of human lifestyle, and the knowledge about their physicochemical characteristics allows for proposing new technological applications. The in natura microfiber of Ochroma pyramidale fruit (IN sample) and its extracted pulp (PU sample) were evaluated by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetry and Differential Scanning Calorimetry (TG/dTG and DSC). Microfibers were composed mainly of (68 ± 1)% holocellulose, (35.8 ± 0.1)% cellulose, (32 ± 3)% lignin and (3.7 ± 0.3)% extractives. The XRD pattern of the PU sample revealed that the mercerization process resulted in the change of the cellulose crystal structure from Iα type (triclinic) to type II (monoclinic). The SEM technique showed that the IN sample presented regular cylindrical/hollow-shaped wire-like microfibers with diameters ranging from 5 µm to 25 µm. However, the mercerization process changed their natural morphology. A significant change in the FTIR spectra after the removal of hemicellulose and lignin components was observed: weak bands at 1739 cm−1 (C=O stretching of lignin and hemicellulose fractions), 1463 cm−1 (CH3 of lignin) and 1246 cm−1 (C-O of lignin) were still observed in the PU sample, indicating that the lignin was not completely removed due to the natural difficulty of isolating pure cellulose. The TG/dTG and DSC evaluation revealed a temperature increase of the second thermal event (starting at 235 °C) in the PU sample, which was assigned to the cellulose and residual hemicellulose degradation. Then, this work aimed to disseminate and characterize a microfiber with unusual characteristics still little explored by the scientific community, as well as its cellulosic pulp, providing information that may be useful in its application in different industries, enabling the positive development of new biocompatible, renewable and sustainable materials.","PeriodicalId":18398,"journal":{"name":"Micro & Nano Letters","volume":"66 1 1","pages":""},"PeriodicalIF":1.3,"publicationDate":"2023-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79283612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Microbial infections are considered one of the most important concerns of the world community. Developing drug delivery systems based on formulation of nanoparticles (NPs) with antimicrobial agents has shown beneficial effectiveness against microbial infections and related antimicrobial resistance. In this study, the authors prepared and characterized a chitosan-based hydrogel loaded with zinc oxide NPs for controlling the release of vancomycin and also improving its antibacterial effect. Characterization studies demonstrated that the developed biopolymeric hydrogel was able to sustain and control the release of vancomycin in response to acidic media for 96 h. Furthermore, antimicrobial studies showed significant and efficient antibacterial activity of prepared hydrogel against Staphylococcus aureus and Pseudomonas aeruginosa. Based on the obtained results, it can be concluded that the prepared chitosan hydrogel (CH) containing zinc oixde (ZnO) NPs has a desirable activity for controlling the release of vancomycin and improving its antibacterial properties.
{"title":"A chitosan-based hydrogel containing zinc oxide nanoparticles as a carrier for improving antibacterial activity and controlling the release of antibiotics","authors":"Ali Rastegari, Fatemeh Hasanshakir, Zohreh Mohammadi, Fatemeh Saadatpor, Homa Faghihi, Fatemeh Moraffah","doi":"10.1049/mna2.12172","DOIUrl":"https://doi.org/10.1049/mna2.12172","url":null,"abstract":"<p>Microbial infections are considered one of the most important concerns of the world community. Developing drug delivery systems based on formulation of nanoparticles (NPs) with antimicrobial agents has shown beneficial effectiveness against microbial infections and related antimicrobial resistance. In this study, the authors prepared and characterized a chitosan-based hydrogel loaded with zinc oxide NPs for controlling the release of vancomycin and also improving its antibacterial effect. Characterization studies demonstrated that the developed biopolymeric hydrogel was able to sustain and control the release of vancomycin in response to acidic media for 96 h. Furthermore, antimicrobial studies showed significant and efficient antibacterial activity of prepared hydrogel against <i>Staphylococcus aureus</i> and <i>Pseudomonas aeruginosa</i>. Based on the obtained results, it can be concluded that the prepared chitosan hydrogel (CH) containing zinc oixde (ZnO) NPs has a desirable activity for controlling the release of vancomycin and improving its antibacterial properties.</p>","PeriodicalId":18398,"journal":{"name":"Micro & Nano Letters","volume":"18 7","pages":""},"PeriodicalIF":1.3,"publicationDate":"2023-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/mna2.12172","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50120243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the case where an interstitial atom is located in a close-packed atomic row of the crystal lattice, it is called a crowdion. Crowdions play an important role in the processes of mass and energy transfer resulting from irradiation, severe plastic deformation, ion implantation, plasma and laser processing, etc. In this work, supersonic N-crowdions (N=1, 2) in fcc lattices of lead and nickel are studied by the method of molecular dynamics. Modeling shows that the propagation distance of a supersonic 2-crowdion in lead at a high initial velocity is less than that of a supersonic 1-crowdion. In other fcc metals studied, including nickel, supersonic 2-crowdions have a longer propagation distance than 1-crowdions. The relatively short propagation distance of supersonic 2-crowdions in lead is due to their instability and rapid transformation into supersonic 1-crowdions. This feature of the dynamics of supersonic N-crowdions in lead explains its high radiation-shielding properties.
{"title":"Simulation of the Dynamics of Supersonic N-Crowdions in fcc Lead and Nickel","authors":"A. Bayazitov, A. Semenov, S. V. Dmitriev","doi":"10.3390/micro3030044","DOIUrl":"https://doi.org/10.3390/micro3030044","url":null,"abstract":"In the case where an interstitial atom is located in a close-packed atomic row of the crystal lattice, it is called a crowdion. Crowdions play an important role in the processes of mass and energy transfer resulting from irradiation, severe plastic deformation, ion implantation, plasma and laser processing, etc. In this work, supersonic N-crowdions (N=1, 2) in fcc lattices of lead and nickel are studied by the method of molecular dynamics. Modeling shows that the propagation distance of a supersonic 2-crowdion in lead at a high initial velocity is less than that of a supersonic 1-crowdion. In other fcc metals studied, including nickel, supersonic 2-crowdions have a longer propagation distance than 1-crowdions. The relatively short propagation distance of supersonic 2-crowdions in lead is due to their instability and rapid transformation into supersonic 1-crowdions. This feature of the dynamics of supersonic N-crowdions in lead explains its high radiation-shielding properties.","PeriodicalId":18398,"journal":{"name":"Micro & Nano Letters","volume":"8 1","pages":""},"PeriodicalIF":1.3,"publicationDate":"2023-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74305274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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