Applicability of Spray Drying Technique to Prepare Nano-Micro Carriers: A Review

Nano-micro carriers loaded with drugs and active biomolecules have gained a lot of attention in the field of health care, agriculture, and the food industry. Various methods have been explored to synthesize nano-micro carriers. However, there is still a constant search to develop a method for the preparation of a large quantity of nano-micro carriers with high loading efficiency. In this regard, spray drying could be a potential technique because of its inherent features like ease to operate, cost-effectiveness, environment-friendly, single step, and scalable. In this review, the focus is on the applicability of spray drying technique to prepare nano-micro carriers which are loaded with drugs, microorganisms, and other active molecules. Subsequently, the application and usefulness of spray-dried products in different research areas like the food industry, remediation of heavy metals and bioprocessing, and drug delivery have been presented. Furthermore, advantages, limitations, and recent developments in the area of spray drying have been discussed. This review presents a glimpse of spray drying techniques to synthesize nano-micro carriers with a wide range of applications.

Investigation of the Optical, Structural and Compositional Properties of Electrodeposited Lead Manganese Sulfide (PbMnS) Thin Films for Possible Device Applications

The properties of PbMnS semiconductor thin films deposited on fluorine-doped tin oxide (FTO) substrate using an electrodeposition method are investigated to determine their possible device applications. Lead acetate, manganese sulfate, and thiourea were used as precursors for sources of lead, manganese, and sulfur ions respectively. The concentration of lead, manganese, and sulfur ions sources with deposition voltage of 1.8 V was kept constant. The films were deposited using three electrodes system of electrodeposition method by varying deposition time. The films were characterized for optical, structural, morphological, and compositional properties and results showed that the absorbance, refractive index, and optical conductivity of the films are high in the visible (VIS) and near-infrared (NIR) regions but decreases in the NIR. These three properties initially increased with an increase in deposition time up to a time of 70 s which has the highest values of these properties before decreasing to lower values. The transmittance and extinction coefficient of the films are low in both VIS and NIR regions. The bandgap energy of PbS was found to be blue shifted with values of 1.51 eV, 1.54 eV, 1.60 eV, 1.45 eV, and 1.35 eV for the films deposited at 30 s, 50 s, 70 s, 90 s, and 110 s respectively. XRD analysis showed that the films are crystalline with sharp peaks positions indexable to crystalline planes of (111), (200), (211), (220), (311) and (400) with average crystallite size in the range of 16.110 nm to 17.218 nm. Energy-dispersive X-ray spectroscopy (EDX) results showed that the films are composed of lead, manganese, and sulfur but there are some impurity elements present mostly as a result of the substrate used. These properties exhibited by the deposited thin films of PbMnS showed that they can be used for many optoelectronic applications such as photovoltaic cells, sensors, photoconductors, etc.

Properties of Electrosynthesized Cobalt Doped Zinc Selenide Thin Films Deposited at Varying Time

Time optimized cobalt-doped zinc selenide thin films have been successfully electrodeposited on fluorine-doped tin oxide substrates. The films were deposited at the varying time of 1 min, 3 mins, and 5 mins respectively. Film thickness, optical, structural, electrical, and morphological properties of the deposited thin films were evaluated. Film thickness estimated using the gravimetric method increased from 294.35 nm to 399.62 nm as deposition time increased. Optical properties showed that the absorbance of the films ranged from 13.58% to 83.15% and was found to increase as deposition time increased. Transmittance ranged from 24.40% to 73.15% and was found to decrease as deposition time increased. The reflectance of the films was found to be low while the energy band gap ranged between 2.10 eV and 2.85 eV. Structural properties confirmed the deposition of ZnSe thin film with crystallite size values that fall between 14.68 nm and 18.60 nm. Dislocation density is ranged from 4.66 × 1015 lines/m2 to 2.97 × 1015 lines/m2 while microstrain ranged between 8.53 × 10-3 and 5.83 × 10-3. Crystallite sizes of the films were found to increase as deposition time increased while dislocation density and microstrain were found to decrease as deposition time increased. Electrical properties showed that the deposited films are semiconducting films with electrical resistivity values of 1.54 × 105 Ω cm-1.83 × 104 Ω cm and electrical conductivity values of 6.30 × 10-6 S/cm-5.47 × 10-5 S/cm. The micrograph of the films showed that the films were made up of nanoparticles and nanofibres of different dimensions. Energy-Dispersive X-Ray Spectroscopy (EDS) spectra of the films confirmed the presence of cobalt, zinc, and selenium.

COVID-19: A Comprehensive View of Diverse Mitigation Measures, Biomaterials and Outlook

COVID-19 the existing contagion is caused by SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2). As of 1st March, 2021, the statistical study shows, 114 million people all over the world have been affected by COVID-19 and in this about 2.53 million deaths have been reported with a recovery of 64.4 million cases. The most commonly testified signs of COVID-19 infection are pyrexia, tussis and tiredness; other symptoms that are less common include deprivation in senses (odor or flavor), pharyngitis, stuffy nose, cephalgia, gastroenteritis etc. Among the reported cases, approximately 10-15% progress to severe disease and 5% becomes critically ill. Most people recover at 2-6 weeks after exposure to the virus, but it is reported that there are some patients who may recur some symptoms for weeks or months after initial recovery although they are not infectious during this period. In this review article, we have briefly discussed the different diagnostic and detection measures that are being clinically practiced and the treatment methods including medicines and vaccines which has been undertaken in the fight against COVID-19. Recent advances in various regulatory measures comprising the application of biomaterials engineering (nanomaterials, biosensors, quantum dots, polymeric array-based vaccines, etc.) and the digital technologies are also discussed. Organoid cultures are also used against SARS-CoV-2 to understand the biological phenomena taking place in the human body through infection, and thereby establishing the necessary trials to control the infection. In short, there is a requirement of the combination of study from multidisciplinary areas to understand the virus better and develop more effective mitigation measures. There are still studies under examination to improve the public health and to have complete control over this novel virus.

Enhancing the Surface Properties and Structure of MWNTs by Effective Ion Beam Irradiation

The effects of irradiating multiwalled carbon nanotubes (MWNTs) with 100 keV He ions on the surface morphology were examined. Due to irradiation effects, the tube diameter reduced as revealed by scanning electron microscopy (SEM). Raman spectroscopy was used to investigate MWNTs by analyzing the principal bands in the spectra of virgin and radiated MWNT specimens. The effects of irradiation fluences on the disorder (D-band) and the graphite (G-band) modes were investigated. The possibility and prospects of using ion irradiation for controlling the wettability of the MWNT surface were investigated. The irradiation facility produces an MWNT coating that is either hydrophobic or hydrophilic to certain liquids. This analysis demonstrates that ion beam irradiation could be used as an alternative tool to change the structure of CNT and enhancing their wettability application, especially in water treatment. According to Raman spectra, when the fluence increases, the MWNTs become disordered due to the defect produced. The amorphous state of MWNTs could be attained with greater ion irradiation fluences.

Manganese Deposition Content in Carbon Nanotubes Based Filters: Energy Dispersive X-ray and Rutherford Backscatter Spectrometry Investigations

Carbon nanotubes (CNTs) based filters have a prospective advantage compared to the commercial filters due to their lightweight and ability to work without electricity or heat. The manganese (Mn) removal from aqueous solutions by oxidized multi-walled carbon nanotubes (O-MWCNTs) was investigated. The filtration performance was studied under ambient conditions: the solution pH, the initial manganese concentration, and the MWCNT-filter mass. The samples of MWCNT-filters were investigated using energy dispersive X-ray spectroscopy (EDS) and rutherford backscatter spectrometry (RBS) to account for the manganese content within the MWCNT-filter. These techniques were conducted to study the oxidation effect on the morphology of MWCNTs and evaluate the oxygen functional groups and the average diameter distribution. Based on these examinations, the competence of Mn removal may exceed 91% for 50 ppm initial concentration of Mn, proposing that functionalized MWCNTs is a promising filter. The Mn removal was achieved at low pH with removal enhancement at the pH of 2. Functionalized MWCNTs based filters are promising candidate for heavy metal ions removal from industrial wastewater.

On the Influence of Internal and External Factors on the Processes of Corrosion-Mechanical Fracture of High-Strength Low-Alloy Steels

The article studies the influence of internal and external factors on the process of corrosion-mechanical fracture. It is shown that depending on the conditions of hydrogen charging (temperature and chemical composition of the corrosive medium, type of polarization), the mechanical properties of low-alloy steels change dramatically during the initial period of the experiment. With further increase in the holding time in a corrosive medium without polarization, there is no significant change in mechanical properties. It was found that an increase in the level of applied tensile stresses leads to a reduction in the incubation period of microcracks during hydrogen cracking. It was found that the sensitivity of low alloy steels to cracking is largely determined by the relaxation ability of the structure-the relaxation of residual peak micro-stresses localized at the grain boundaries and substructure boundaries reduces the sensitivity to corrosion-mechanical fracture.

Electrochemical Detection of 4-Nitrophenol by Using Graphene Based Nanocomposite Modified Glassy Carbon Electrodes: A Mini Review

This article describes the fabrication of electrochemical devices for the detection of a key environmental pollutant, 4-Nitrophenol (4-NPh). 4-NPh is a requirement for the synthesis of organophosphate pesticides. These pesticides are mostly used in the agricultural sector to obtain a high yield of agricultural products. The use of 4-NPh in the agricultural field results in poisonous levels of this compound in the soil and water. Different techniques have been used for its transformation by biological and chemical degradation. However, these strategies not only created highly toxic pollutant but also need fast operation and time consuming processes. In this background, we have reported a broad and efficient review of the electrochemical reduction of 4-NPh as a feasible alternate method. In this review paper, graphene oxide (GO), reduced graphene oxide (rGO), N-doped graphene oxide, functionalized graphene oxide, metallic nanoparticles coated graphene oxide, metal oxides covered on rGO, polymer functionalized graphene oxide and hybrids materials functionalized with graphene oxide (hydroxyl apatite and β-cyclodextrin) which have been fabricated on a glassy carbon electrode (GCE) to enhance the electrocatalytic reduction and increase the sensor activity of 4-NPh are discussed. We have also described the effects of a few interfering phenolic pollutants such as aminophenol, hydroquinone, o-nitrophenol (o-NPh), trinitrotoluene, trinitrophenol, 2, 4-dinitrophenol (4-DNPh) and nitrobenzene. In the paper, easy and more effective electrochemical methods for the detection of 4-NPh with graphene- based nanocomposites modified on GCE for 4-NPh detection are summarized and discussed.

Optimization and Feasibility of Alizarin Red S Retention on Iron- Loaded Cellulose Nanocomposite Bead

Iron(III) loaded cellulose nanocomposite bead, synthesized through sol-gel method, was characterized by Fourier transform infra-red spectroscopy, field emission scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy, tunneling electron microscopy, and tested for adsorptive removal of alizarin red S from aqueous solution. The influence of variables such as pH, contact time, initial dye concentration, adsorbent dose and temperature for dye retention were investigated in batch operation. The process was optimized by employing response surface methodology following full factorial and central composite design. The maximum adsorption of 97% was observed at an optimum condition of pH 3.0, dose of 2.0 gdm-3 and shaking time of 45 mins corresponding to the dye concentration of 100 mgdm-3 at 303 K. Correlation of cooperative influences of the significant variables and the extent of dye adsorption were represented by a second order polynomial equation. The mutual interactions of the significant variables were presented by 3D response surface and 2D contour plots in the design space. The adsorption was better described by Langmuir isotherm and pseudo second order kinetics. The process was spontaneous (-∆G°, 48.19 kJmol-1 ), feasible (∆S°, 0.284 Jmol -1 K-1 ) and endothermic (∆H°, 71.62 kJmol-1 ). The adsorbent can be regenerated with NaOH (10.0 × 10-2 M) and recycled for reuse, at least for five successive operations.

Porous Carbons Derived from Ginkgo Shell Used for High-Performance Supercapacitors

As a renewable biomass and a low-cost crude carbon source, the ginkgo shell is explored for preparing high-value porous carbon via carbonization and the following KOH activation. Structure characterization shows that GSPC has microporous and mesoporous structure with specific surface area (SSA) of up to 1941 m2 g-1 , which exhibits superior capacitive properties. In a three-electrode system by using 6 M KOH as electrolyte, GSPC-700-1:2 could deliver a high specific capacitance of 345 F g-1 at 0.5 A g-1 . Even at a high current density of 20 A g-1 , the specific capacitance of as high as 280 F g-1 can be still maintained. Furthermore, a symmetric supercapacitor device (SCD) is fabricated by GSPC-700-1:2, which exhibits a capacitance retention rate of 83% at 5 A g-1 after 10000 charging/discharging cycles. A power density of 301 W kg-1 is achieved at an energy density of 13 W h kg-1 . The superior electrochemical performance demonstrates that ginkgo shell can function as a new biomass material for the production of porous carbon materials that are used in high-performance supercapacitors and other energy storage devices.