Solubility of sodium oxalate in kraft black liquors below 100°C

Precipitation of sodium salts from kraft black liquor leads to scale formation in the evaporation plants of kraft pulp mills. Sodium oxalate scaling is most prevalent in mills pulping tropical hardwoods such as eucalyptus and acacia, but it has also been found in the scales in high solids lines after the concentrators in mills pulping softwoods. There is very limited solubility data for sodium oxalate in black liquor, especially below 100°C. This study measures the solubility limit in four different black liquors from 14% to 47% dry solids between 50 and 90°C. The newly generated solubility data in black liquors enhance our understanding of sodium oxalate scale formation in low solids effects of the evaporation plant. An example of an application to a kraft pulp mill with sodium oxalate scaling in the seventh effect is given.     

Dual-drug delivery of sodium ceftriaxone and metronidazole by applying salt-assisted chitosan nanoparticles: Stability,drug release,and time-kill assay study against Bacteroides fragilis

The purpose of this study was to develop a polymeric biomaterial with regulated dual drug release and increased bactericidal strength of the antibiotics sodium ceftriaxone (CTX) and metronidazole (MTZ) for the treatment of intra-abdominal infections. Chitosan nanoparticles (CS NPs) were produced by ionic crosslinking process in the presence of NaCl monovalence salt. The antibacterial activity and drug release behavior of CS NPs were investigated against anaerobic Bacteroides fragilis. The optimum initial drug ratio for designing dual drug carriers containing CTX and MTZ in a 4:3 ratio was 1:1. After 6 months, the salt-assisted CTX-MTZ-loaded CS NPs were 300 nm in size and had a polydispersity index of 0.09 with high stability. It has been demonstrated that drug release from NPs is more tightly controlled than drug release from free drugs. Furthermore, the data show that the minimum inhibitory concentration and minimum bactericidal concentration for nanostructure carriers are one-quarter of those of free medicines. Free drugs could completely kill the bacterium after 24 h, but the dual drug carrier could kill the bacteria in 10 h. Finally, salt-assisted CTX-MTZ-loaded CS NPs were proposed as a feasible alternative to standard intra-abdominal infection treatment.     

Poly(vinylidene fluoride-co-hexafluoro propylene) membranes prepared via thermally induced phase separation and application in direct contact membrane distillation

A non-toxic and environmentally safe diluent, acetyl tributyl citrate, was employed to prepare poly(vinylidene fluoride)-co-hexafluoropropylene membranes via thermally induced phase separation. Effects of the polymer concentration on the phase diagram, membrane morphology, hydrophobicity, pore size, porosity and mechanical properties (tensile stress and elongation at break) were investigated. The results showed that the pore size and porosity tended to decrease with increasing polymer concentration, whereas the contact angle, liquid entry pressure and mechanical properties showed the opposite trend. In direct contact membrane distillation operation with 3.5 wt-% sodium chloride solution as the feed solution, the prepared membranes performed high salt rejection (>99.9%). Furthermore, the prepared membranes retained excellent performance in long-term stability tests regarding the permeate flux and salt rejection.     

Real-time vibration monitoring and analysis of agricultural tractor drivers using an IoT-based system

Agricultural tractor drivers experience a high amplitude of vibration, especially during soil tillage operations. In the past, most research studied vibration exposure with more focus on the vertical (z) axis than on the fore-and-aft (x) and lateral (y) axes. This study examines how rotary soil tillage affects the vibration acceleration and frequency, and the power spectral densities (PSDs) at the seat pan and head along three translational axes in a real-field multiaxis vibration context. Moreover, this study aimed to identify the characteristics of the seat-to-head transmissibility (STHT) response to identifying the most salient resonant frequencies along the x-, y-, and z-axes. Nine (9) male tractor drivers operated the tractor with a mounted rotary tiller throughout the soil tillage process. In the event of a COVID-19 pandemic, and to respect social distancing, this study developed an Internet of Things (IoT) module with the potential to integrate with existing data loggers for online data transmission and to make the experimentation process more effective by removing potential sources of experimenter errors. The raw acceleration data retrieved at the seat pan and the head were utilized to obtain daily exposure (A(8)), PSDs, and STHT along the x-, y-, and z-axes. The vibration energy was found to be dominant along the z-axis than the x- and y-axes. A(8) response among tractor drivers exceeds the exposure action value explicitly stated by Directive 2002/44/EU. PSDs along the x-, y-, and z-axes depicted the low-frequency vibration induced by rotary soil tillage operation. The STHT response exhibited a higher degree of transmissibility along the y- and z-axes when compared with that along the x-axis. The frequency range of 4–7 Hz may plausibly be associated with cognitive impairment in tractor drivers during rotary soil tillage.     

Structural isomers in the perkin reaction. II. Products of interaction of 4-bromophthalic anhydride with phenylacetic acids and some of their reactions

Isomeric bromobenzalphthalides of type 1 were obtained by condensation of 4-bromophthalic anhydride with phenylacetic acids. Isomeric benzalphthalimidines of type 6–11 were also prepared and some of their reactions discussed.     

Fabrication and Properties of a Gel-Cast Dense Silicon Carbide Body

Silicon - In this research, the effect of different parameters on the behavior of suspension rheology, as well as the physical and mechanical properties of green and sintered SiC bodies, were...