Dissolution enhancement of a poorly water-soluble antimalarial drug by means of a modified multi-fluid nozzle pilot spray drier

A spray drier with a modified multi-fluid nozzle was used to prepare microparticles of a poorly water-soluble antimalarial drug, artemisinin (ART), with the aim of improving its dissolution in water. ART was co-spray dried with a hydrophilic polymer, polyethylene glycol (PEG). The differential scanning calorimetry and X-ray diffraction studies showed that the crystallinity of ART decreased after spray drying. Compared to the physical mixture of ART and PEG, the amorphous phase of ART in the spray dried ART–PEG composites increased, which depended on the weight ratio of drug to polymer. The phase-solubility studies revealed that the aqueous solubility of ART was improved by the presence of PEG. The dissolution of ART from the spray dried ART–PEG composites was more rapid than that from their respective physical mixture and the original ART powder. For example, the dissolution of ART from the spray dried ART–PEG composite (1:6) was 6.5 times higher than that from the original ART powder in the first 30 min. In the mathematical modeling, the Weibull and Korsemeyer–Peppas models were found to best fit to the in vitro dissolution data and then the drug release mechanism was considered as the Fickian diffusion.     

Multiwalled carbon nanotube‐filled ethylene acrylic elastomer nanocomposites: Influence of ionic liquids on the mechanical,dynamic mechanical,and dielectric properties

Electrically conductive nanocomposites based on ethylene acrylic elastomer (AEM) and multiwalled carbon nanotube (MWNT) have been successfully prepared. Before mixing the MWNT is dispersed in ethanol in presence of ionic liquids such as 1‐methyl‐3‐octylimidazolium chloride (MOIC) and 1‐allyl‐3‐methyl imidazolium chloride (AMIC). Uniform dispersion of MWNT in the nanocomposites is achieved in presence of ionic liquid, which is confirmed by the high‐resolution transmission electron microscopic (HRTEM) microphotographs. The tensile strength increases up to 6 phr of MWNT loading and above that it decreases. However, the tensile strength increases due to the incorporation of ionic liquid assisted dispersed MWNT. It is observed from the dynamic mechanical analysis (DMA) that the storage modulus (E′) and glass transition temperature (T_g) of AEM matrix increase by incorporation of MWNT. The E′ also increases and the tan δ_max marginally decreases due to the incorporation of dispersed MWNT in presence of ionic liquids. The dielectric relaxation characteristic properties of AEM/MWNT nanocomposites such as dielectric permittivity (ε′), AC conductivity (σ_ac), impedance (Z^*) have been studied as a function of frequency (10¹−10⁶ Hz) in presence of ionic liquids. The ε′ and σ_ac increase with increasing the MWNT loading due to the easy orientation of dipoles and formation of interconnected conductive networks in the nanocomposites. The electromagnetic interference shielding effectiveness (EMISE) is studied in the X‐band frequency range of 8 to 12 GHz, which significantly improved with increase in MWNT loading. POLYM. COMPOS., 37:2568–2580, 2016. © 2015 Society of Plastics Engineers     

Error feedback based noise shaping in a double sampled ADC

A first order error feedback based noise shaping ADC, that obviates the need for high-gain and high output-swing op amps and fast-settling, power-hungry, and noisy reference buffers is proposed. Using a single stage op amp with a gain of 70 (i.e. 37 dB) and output swing of ±75 mV, this topology, realized in GPDK 90-nm CMOS technology, achieves an SNDR of 63 dB operating at 1 GHz (effective sample rate of 2 GHz due to double sampling) with an OSR of 32.     

Development of ionic and non‐ionic natural gum‐based bigels: Prospects for drug delivery application

Recently, much attention has been focused on the development of gel based formulations for controlled drug delivery applications. Herein, we report the effect of the ionic (gum acacia) and the non‐ionic (guar gum) gums on the properties of the bigels prepared with fluid‐filled organogels. The microscopic study suggested the presence of flocculated structure in guar gum bigel, whereas, a de‐flocculated structure was observed in gum acacia bigel. Infrared spectroscopy suggested the presence of polysaccharides in the bigels. The mechanical properties of the guar gum bigel were better than gum acacia bigel. The conductivity and the release properties suggested superior properties of gum acacia bigel. This indicated that the ionic nature of acacia bigel played a major role in controlled drug delivery, making it a potential bigel for desired pharmaceutical applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42561.     

Microstructure evolution of Al-Si-10Mg in direct metal laser sintering using phase-field modeling

Direct metal laser sintering (DMLS) has evolved as a popular technique in additive manufacturing, which produces metallic parts layer-by-layer by the application of laser power. DMLS is a rapid manufacturing process, and the properties of the build material depend on the sintering mechanism as well as the microstructure of the build material. Thus, the prediction of part microstructures during the process may be a key factor for process optimization. In addition, the process parameters play a crucial role in the microstructure evolution, and need to be controlled effectively. In this study, the microstructure evolution of Al-Si-10Mg alloy in DMLS process is studied with the help of the phase field modeling. A MATLAB code is used to solve the phase field equations, where the simulation parameters include temperature gradient, laser power and scan speed. From the simulation result, it is found that the temperature gradient plays a significant role in the evolution of microstructure with different process parameters. In a single-seed simulation, the growth of the dendritic structure increases with the increase in the temperature gradient. When considering multiple seeds, the increasing in temperature gradients leads to the formation of finer dendrites; however, with increasing time, the dendrites join and grain growth are seen to be controlled at the interface. The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-018-0213-1     

Preparation of Sm2O3 and Co3O4 from SmCo magnet swarf by hydrometallurgical processing in chloride media

The recycling of rare earth elements(REE) from end-of-life REE based products is an environment friendly proposition. Waste Sm-Co based permanent magnet generated during machining is a good source for both Sm and Co. In the present study a simpler process of acid leaching at 80 ℃ followed by solvent extraction, oxalate precipitation and calcination is described for producing pure Sm_2 O_3 and Co_3 O_4. With either 10 vol% H_2SO_4 or 15 vol% HCI at 80 ℃ more than 95% Sm and Co are leached in 1 h.Extraction of Sm from sulphate leach liquor with TBP or Aliquat 336 was poor. Although extraction with TOPS-99 is quantitative but Sm from sulphate leach liquor precipitated as Sm_2(SO_4)_3·8 H_2 O. The chloride leach liquor at an initial pH of 2.5 and with 1.2 mol/L TOPS-99 shows requirement of 4-stages at A:O = 3:2. Stripping with oxalic acid precipitates Sm-oxalate which is calcined at 800 ℃ to produce Sm_2 O_3. Co_3 O_4 is recovered from the raffinate through oxalate precipitation followed by calcination at450℃.     

Laminar convection in wall sub-channels and transport rates for finite rod-bundle assemblies by superposition

Finite rod-clusters in circular, square and hexagonal shells have been divided along the symmetry lines into a number of interior, wall and corner subchannels. Laminar fluid flow and heat transfer results have been generated for these subchannels with varying pitch-to-diameter and wall distance-to-diameter ratios. Wall shear stress and temperature variations for typical wall subchannels are presented. Friction factor values for finite bundles are then obtained by superposing the results of the subchannels that constitute the bundles. The values so generated are in excellent agreement with previous work in the literature obtained by the method of symmetry sectors. Considerable disagreements were, however, observed in the superposed values of Nusselt number, apparently due to conduction effects.     

A finite element modeling-based approach to predict vibrations transmitted through different body segments of the operator within the workspace of a small tractor

Agricultural tractor drivers are subjected to high levels of whole-body vibrations and hand arm vibrations during most part of the farm activities due to unevenness of field surface, uneasy posture, improper workplace design, moving parts of the tractor, and other unavoidable circumstances. The comfort level of the operator inside a dynamic tractor is dependent on the level of vibration generated inside the different human body segments. In the present study, a finite element modeling was proposed to predict vertical vibrations (Z-axis) and frequencies at the different body segments of the seated small tractor operator. The forces required for different controls of the tractor were measured to be used as input parameters in the finite element modeling. The maximum mean forces of the brake (172.8 N) and clutch (153.2 N) were used as the input parameters for the simulation study. The simulated results were validated with the field measured values of vertical accelerations at selected body segments of the operator. The simulation could successfully predict vertical vibrations at selected points of interest (i.e., foot, leg, thigh, lower arm, upper arm, back, and head) except the chest of the body, as the buttock of the operator model was fixed (degree of freedom is equal to zero) in the simulation. The obtained results were compared with the international standards ISO 2631-1 (1985/1997) and ISO 5349-1 (2001) to assess the vibration characteristics at the different body segments of the operator. The foot, leg, lower arm, and upper arm of the operator were subjected to vertical vibration frequencies from 10 to 200 Hz. Most of the resonance of vertical accelerations occurred in one-third octave bands of 20–80 Hz frequencies. The thigh, chest, back, and head of the operator were exposed to vibration frequencies below 40 Hz during field operation. At these parts of the body, the vertical acceleration resonated at lower frequencies, between 2 and 8 Hz.     

A study on micro-mechanical deformation behaviour of heat-treated 20MnMoNi55 steel

Several heat treatment procedures are designed considering critical temperatures of phase transformation evaluated through dilatometric testing of 20MnMoNi55 steel to transform low carbon bainitic as-received material into ferrite-martensite dual-phase steels consisting of varied martensite fractions. A thorough metallographic study correlated with the micro-hardness of constituent phases ensures morphological characteristics along with its fractional variations in as-received and dual-phase steels. The impact of fractional variation in constituent phases on the uniaxial monotonic deformation characteristics of dual-phase steels has been observed with a correlation study between experimental tensile and finite element simulated results. Therefore, a physical-based model with a 2-dimensional representative volume element has been established, addressing actual morphological characteristics obtained from metallographic studies. Moreover, the constitutive flow behaviours of ferrite and martensite are also derived from the dislocation-based hardening model to address the actual deformation phenomenon. Finally, an inhomogeneous deformation behaviour among constituent phases and localization of plastic strain in ferrite matrix has been observed with von-Mises stress, and equivalent plastic strain distribution through finite element simulated results. This phenomenon is again confirmed with kernel average misorientation mapping and geometrically necessary dislocation density evaluation through electron backscattered diffraction of tensile samples subjected to different degrees of plastic strain.     

Charge Matters: Mutations in Omicron Variant Favor Binding to Cells

Evidence is strengthening to suggest that the novel SARS-CoV-2 mutant Omicron, with its more than 60 mutations, will spread and dominate worldwide. Although the mutations in the spike protein are known, the molecular basis for why the additional mutations in the spike protein that have not previously occurred account for Omicron's higher infection potential, is not understood. We propose, based on chemical rational and molecular dynamics simulations, that the elevated occurrence of positively charged amino acids in certain domains of the spike protein (Delta: +4; Omicron: +5 vs. wild type) increases binding to cellular polyanionic receptors, such as heparan sulfate due to multivalent charge-charge interactions. This observation is a starting point for targeted drug development.