Thermal Stability of Mg2Si0.6Sn0.4 under Oxidation Conditions

The use of Mg₂Si_0.6Sn_0.4 under air in thermoelectric modules in the mid-temperature range of 400-600 °C is linked to its ability to resist oxidation. In this study, oxidation experiments performed at 400 °C under air evidenced the stability of the material, either under static conditions (up to 100 h) or under severe heating-cooling cyclic conditions (up to 400 cycles), showing its ability to be used in a reliable way at this temperature. By combining thermogravimetry, scanning electron microscopy, temperature X-ray diffraction analysis, and mechanical and thermodynamic considerations, a mechanism is proposed explaining how Mg₂Si_0.6Sn_0.4 further undergoes decomposition with time under air when treated above 500 °C. The presence of Sn and the formation of various oxides are the key parameters of the material's degradation.

Continuous manufacture of hydroxychloroquine sulfate drug products via hot melt extrusion technology to meet increased demand during a global pandemic: From bench to pilot scale

During pandemics and global crises, drug shortages become critical as a result of increased demand, shortages in personnel and lockdown restrictions that disrupt the supply chain. The pharmaceutical industry is therefore moving towards continuous manufacturing instead of conventional batch manufacturing involving numerous steps, that normally occur at different sites. In order to validate the use of large-scale industrial processes, feasibility studies need to be performed using small-scale laboratory equipment. To that end, the scale-up of a continuous process and its effect on the critical quality attributes (CQAs) of the end product were investigated in this work. Hydroxychloroquine Sulphate (HCQS) was used as the model drug, Soluplus® as a model polymeric carrier and both horizontal and vertical twin screw extruders used to undertake this hot melt extrusion (HME) study. Seven formulations were processed using a small-scale horizontal extruder and a pilot-scale vertical extruder at various drug loadings, temperature profiles and screw speeds. When utilising a horizontal extruder, formulations with the highest drug load and processed at the lowest screw speed and temperature had the highest crystallinity with higher drug release rates. Upon scale-up to a vertical extruder, the crystallinity of the HCQS was significantly reduced, with less variation in both crystallinity and release profile across the different extrudates. This study demonstrates improved robustness with the pilot-scale vertical extruder compared to lab-scale horizontal extruder. The reduced variation with the vertical extruder will allow for short increases in production rate, with minimum impact on the CQAs of the final product enabling high-performance continuous manufacturing with minimum waste of raw materials. Finally, this research provides valuable information for the pharmaceutical industry in accessing continuous technologies for the manufacture of pharmaceutical products, allowing for efficient utilisation of resources upon scale-up and mass production during global pandemics and drug shortages.

[Comparison of adhesive seal morphology between APC™ PLUS and APC™ Flash-Free Adhesive Coated brackets]

INTRODUCTION

Does the new adhesive-coated APC™ Flash-Free bracket from the 3M Unitek^® group simplify the bonding protocol without compromising precision?

OBJECTIVES

The aim of this study was to compare the morphology of the adhesive joint between the classic APC™ PLUS adhesive-coated brackets and APC™ Flash-Free brackets.

MATERIALS AND METHODS

In vitro bonding of esthetic brackets in the CLARITY™ ADVANCED range was performed to compare the morphology of the excess flash between APC™ PLUS and APC™ Flash-Free brackets.

RESULTS

No statistically significant difference was found concerning the morphology of the excess flash between APC™ PLUS and APC™ Flash-Free brackets. A statistically significant difference was found regarding the thickness of the adhesive between the two types of bracket. The adhesive used for the APC™ Flash-Free brackets was significantly thicker than for the APC™ PLUS brackets (P=0.0001). Adhesive thickness was also more homogeneous on the APC™ Flash-Free brackets (P=0.001 for the relative difference).

CONCLUSION

The adhesive is thicker but adhesive homogeneity is greater with APC™ Flash-Free brackets than with APC™ PLUS brackets.

Synthesis, Crystal Structure, and Transport Properties of the Hexagonal Mo9 Cluster Compound Ag3RbMo9Se11

Mo-based cluster compounds are promising candidates for thermoelectric applications at high temperatures due to their very low lattice thermal conductivity values. Here, we report on a detailed investigation of the crystal structure and transport properties measured in a wide range of temperatures (2-800 K) of polycrystalline Ag₃RbMo₉Se₁₁. Single-crystal X-ray diffraction shows that this compound crystallizes in the hexagonal space group P6₃/m. The crystal structure is formed by stacked Mo₉Se₁₁ units leaving channels that are randomly filled by Rb⁺ cations, while Ag⁺ cations are located between the Mo₉Se₁₁ units. The high disorder in the unit cell induced by these atoms and their large anisotropic thermal displacement parameters are two key characteristics that lead to very low lattice thermal conductivity as low as 0.6 W m^-1 K^-1 at 800 K. The combination of semiconducting-like electrical properties and low ability to transport heat leads to a maximum dimensionless thermoelectric figure of merit ZT of 0.4 at 800 K.

Bacteriophilic tetra-p-guanidinoethyl-calix[4]arene derived polymers. Syntheses and E. coli sequestration studies

New resins functionalized by the antibacterial tetra-p-guanidinoethylcalix[4]arene were synthesized, and their bacteriophilic properties were evaluated (E. coli) by capillary electrophoresis.

Impact of Maintenance Therapy for the Prevention of Peri-implant Diseases: A Systematic Review and Meta-analysis

At the present time, peri-implantitis has become a global burden that occurs with a frequency from 1% to 47% at implant level. Therefore, we aimed herein at assessing the impact of peri-implant maintenance therapy (PIMT) on the prevention of peri-implant diseases. Electronic and manual literature searches were conducted by 3 independent reviewers using several databases, including MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and Cochrane Oral Health Group Trials Register, for articles up to June 2015 without language restriction. Articles were included if they were clinical trials aimed at demonstrating the incidence of peri-implant diseases under a strict regime or not of PIMT. Implant survival and failure rate were studied as secondary outcomes. A meta-analysis was conducted to evaluate the influence of PIMT and other reported variables upon peri-implant diseases. Thirteen and 10 clinical trials were included in the qualitative and quantitative analysis, respectively. Mucositis was affected by history of periodontitis and mean PIMT at implant and patient levels, respectively. Similarly, significant effects of history of periodontal disease were obtained for peri-implantitis for both implant and patient levels. Furthermore, mean PIMT interval was demonstrated to influence the incidence of peri-implantitis at implant but not patient level. PIMT interval showed significance at both levels. For implant survival, implants under PIMT have 0.958 the incident event than those with no PIMT. Within the limitations of the present systematic review, it can be concluded that implant therapy must not be limited to the placement and restoration of dental implants but to the implementation of PIMT to potentially prevent biologic complications and hence to heighten the long-term success rate. Although it must be tailored to a patient's risk profiling, our findings suggest reason to claim a minimum recall PIMT interval of 5 to 6 mo. Additionally, it must be stressed that even in the establishment of PIMT, biologic complications might occur. Thus, patient-, clinical-, and implant-related factors must be thoroughly explored.

A bacteriophilic resin, synthesis and E. coli sequestration study

The polycationic pyridinium-Merrifield resinIwas prepared and subjected to bacteria sequestration studies. Its efficiency was demonstrated by capillary electrophoresis titrations, and the effectiveness of the sequestration was shown by confocal microscopy.

Cu2+-doped zeolitic imidazolate frameworks (ZIF-8): efficient and stable catalysts for cycloadditions and condensation reactions

Condensations and cycloadditions can be catalyzed by newly synthesized Cu-doped zeolitic imidazolate frameworks (ZIFs). The catalysts were well characterized and reusable.

Fe3O4@ZIF-8: magnetically recoverable catalysts by loading Fe3O4 nanoparticles inside a zinc imidazolate framework

Synthesis and characterization of Fe₃O₄ nanoparticles encapsulated in ZIF-8 crystals along with their catalytic properties and reusability are presented.

Controlling ZIF-8 nano- and microcrystal formation and reactivity through zinc salt variations

The reactivity of the zinc(+2) salt allows tuning of the size and catalytic activity of ZIF-8 crystals.

[Behavior disorder of the REM sleep in 2 documented cases with polysomnography]

We report a 69 years old male with a parkinsonian syndrome and a 50 years old female without neurological problems who showed violent behavior during REM sleep. Polysomnography showed that both bad tonic or phasic muscular activity during REM sleep and a REM sleep behavior disorder was diagnosed. Clonazepam was used in both, with good clinical response. This condition is frequently unrecognized and confused with nightmares, nocturnal delirium or other parasomnias.

[Foramen ovale electrodes in the study of temporal lobe epilepsy]

Corticograms of the mesial structures of the temporal lobe may be obtained with the recently developed foramen ovale electrodes. Since their installation is easy and of low risk, they will probably displace other invasive techniques routinely used up to the moment for the localization and lateralization of epileptic foci originated in the temporal lobe. For the first time in our country, we have used this technique in 7 patients with medically intractable complex partial epilepsy. In all the patients, the study allowed to clear doubts about the laterality of the start of ictal activity and to define irritative foci not found with conventional continuous superficial electroencephalographic recordings. The procedure was uneventful and the implanted electrodes were optimally tolerated. Foramen ovale electrodes are an effective diagnostic method for temporal lobe epilepsies and their features are specially appropriate for our milieu.