Development of a Robust PET-RAFT Polymerization Using Graphitic Carbon Nitride (g-C3N4)

The metal-free semiconductor, graphitic carbon nitride (g-C3N4), was introduced into RAFT polymerization for the first time. The production of linear polyacrylate and polyacrylamide has been achieved via PET-RAFT polymerization using g-C3N4 as a photoactive organocatalyst without prior deoxygenation. The resulting polymers display controlled molecular weights, narrow polymer dispersities, and high end-group fidelity as exemplified by 1H NMR analysis, MALDI-TOF-MS measurement, and chain extension experiment. Temporal control is illustrated by intermittent light and dark cycles, with polymer growth arrested in the absence of irradiation. The effects of changing RAFT agents (i.e., trithiocarbonates), solvents, catalyst concentrations, and degrees of polymerization in this system have been investigated. The successful polymerization of nonpurified monomer (i.e., still containing radical inhibitors) demonstrates the robust nature of the presented PET-RAFT system

Hand-portable HPLC with broadband spectral detection enables analysis of complex polycyclic aromatic hydrocarbon mixtures

Polycyclic aromatic hydrocarbons (PAHs) are considered priority hazardous substances due to their carcinogenic activity and risk to public health. Strict regulations are in place limiting their release into the environment, but enforcement is hampered by a lack of adequate field-testing procedure, instead relying on sending samples to centralised analytical facilities. Reliably monitoring levels of PAHs in the field is a challenge, owing to the lack of field-deployable analytical methods able to separate, identify, and quantify the complex mixtures in which PAHs are typically observed. Here, we report the development of a hand-portable system based on high-performance liquid chromatography incorporating a spectrally wide absorption detector, capable of fingerprinting PAHs based on their characteristic spectral absorption profiles: identifying 100% of the 24 PAHs tested, including full coverage of the United States Environmental Protection Agency priority pollutant list. We report unsupervised methods to exploit these new capabilities for feature detection and identification, robust enough to detect and classify co-eluting and hidden peaks. Identification is fully independent of their characteristic retention times, mitigating matrix effects which can preclude reliable determination of these analytes in challenging samples. We anticipate the platform to enable more sophisticated analytical measurements, supporting real-time decision making in the field

Accuracy of working length determination with root ZX apex locator and radiography: An in vivo and ex vivo study

The purpose of this study was to clinically compare working length (WL) determination with root ZX apex locator and radiography, and then compare them with direct visualization method ex vivo. A total of 75 maxillary central and lateral incisors were selected. Working length determination was carried out using radiographic and electronic apex locator methods. Subsequently, the tooth under study was extracted and actual working length was determined directly under a stereomicroscope. Data were analyzed by Wilcoxon signed-rank, Spearman’s correlation coefficient and intra-class correlation tests. All the statistical analyses were set with a significance level of α = 0.05. The absolute measurement errors of the two methods were compared using Wilcoxon signed test, exhibiting no statistically significant difference in measurement errors between the two methods. Descriptive evaluation revealed that in 72% (n = 54) of the specimens, both methods had errors in the same direction and in 28% (n = 21) of the specimens, the two methods had errors in opposite directions. Intra-class correlation coefficient test demonstrated a high degree of agreement between the two methods. In conclusion, this study did not show any difference between radiography, root ZX and direct visualization in WL determination.Key words: Working length, electronic apex locator, root ZX, radiography

Zero electrical power pump for portable high-performance liquid chromatography

A major trend in analytical chemistry is the miniaturization of laboratory instrumentation. We report a pump requiring no power to operate based on the controlled expansion of a pre-pressurised gas for use in portable applications of high-performance liquid chromatography. The performance of the gas pump is characterised and integrated into a compact liquid chromatography system capable of isocratic separations integrating an LED-based UV-absorption detector. The system weighed 6.7 kg when the mobile phase reservoir was fully charged with 150 mL solvent and included an on-board computer to control the system and analyse data. We characterise the flow-rate through chromatography columns with a variety of geometries and packing materials for a range of pressures up to 150 bar. The maximum variation in flow rate was measured to be 6.5 nL min−1, limited by the resolution of the flow detector. All tests were made on battery power and results are a mixture of those made in the laboratory and in the field. Additionally, we performed a series of 1 m drop tests on the device and show the system's high tolerance to mechanical shocks during operation in the field

The role of phosphonate speciation on the inhibition of barium sulfate precipitation

The inhibition of barium sulfate precipitation in the presence of phosphonate containing molecules was investigated experimentally and speciation curves were used to elucidate the interactions involved. Inhibition of precipitation was found to be pH dependent and loss of inhibition was observed at both very high and low pHs. Maximum inhibition for all the inhibitor molecules occurred at pH 8. While speciation curves showed that inhibition could be improved by the presence of 2 or more fully de-protonated phosphonate groups (for pure aminophosphonates) on the molecule at pH 8, at pH 12 inhibition was insensitive to the number of de- protonated phosphonate groups. It is, therefore, suggested that surface charge repulsion affects inhibition at very high pH. For molecules which are not pure aminophosphonates, stereochemistry as well as functional groups and their ionisation state appear to play a significant role in inhibition at 3<pH8

Herbal-based drugs for dry eye; treatment and adverse reaction

33-40Dry eye syndrome is one of the most common types of eye diseases. Due to the significant prevalence of the disease, there is an important need for treatment of dry eye in a simple but efficient way. Artificial tears are the most common agents used for treating dry eye but are not very useful. In recent years, the use of herbal remedies has attracted much attention, because the process of producing most herbal remedies is simple, inexpensive and has fewer side effects. In many clinical studies, the potential interactions between medicines and herbs have been demonstrated. According to reports, some herbal products have the potential to be used for the treatment of dry eye while the use of certain products can lead to this syndrome. In this review, we have listed some of the herbal drugs and components which can prevent or treat the dry eye or cause it

Progress and Perspectives Beyond Traditional RAFT Polymerization.

The development of advanced materials based on well-defined polymeric architectures is proving to be a highly prosperous research direction across both industry and academia. Controlled radical polymerization techniques are receiving unprecedented attention, with reversible-deactivation chain growth procedures now routinely leveraged to prepare exquisitely precise polymer products. Reversible addition-fragmentation chain transfer (RAFT) polymerization is a powerful protocol within this domain, where the unique chemistry of thiocarbonylthio (TCT) compounds can be harnessed to control radical chain growth of vinyl polymers. With the intense recent focus on RAFT, new strategies for initiation and external control have emerged that are paving the way for preparing well-defined polymers for demanding applications. In this work, the cutting-edge innovations in RAFT that are opening up this technique to a broader suite of materials researchers are explored. Emerging strategies for activating TCTs are surveyed, which are providing access into traditionally challenging environments for reversible-deactivation radical polymerization. The latest advances and future perspectives in applying RAFT-derived polymers are also shared, with the goal to convey the rich potential of RAFT for an ever-expanding range of high-performance applications

Association between proximal femoral geometry and incidence of proximal femoral fractures

Introduction: Recently, proximal femur geometry has been identified as a risk factor for hip fracture, and studies about the association of proximal femoral geometric indices with these fractures worldwide have reported inconsistent results. In this study, this association was studied in an Iranian population. Materials and Methods: In this case control study that was performed in Ayatollah Kashani Hospital in 1395 in Shahrekord, 81 patients with proximal femur fracture were trained with low energy and 83 healthy subjects over 50 years old. After recording the demographic data, the pelvic radiograph was taken and femoral neck width (FNW), femoral Shaft Diameter (FSD), femoral neck axis length (FNAL), hip axis length (HAL) and neck shaft angle (NSA) parameters were measured in both groups using orthopedic ruler. Data analysis was performed using stata software. Results: The mean age of case group (70.81±13.86 years) was significantly higher than control group (61.35±9.89 years) (P=0.00). Intrestingly, the mean height and weight of case group were lower than control group (P0.05). Conclusion: In this study older age, female sex, shorter heights, and less weight were associated with the incidence of proximal femoral fractures. Conclusively, FNAL, HAL, FSD, and NSA could not predict proximal femoral fractures in our samples. However, FNW reduction significantly increased the risk of femoral neck fractures in both male and female patient

Monitoring light‐driven oxygen insertion reactions into metal carbon bonds by LED‐NMR spectroscopy

The facile light-driven insertion reaction of oxygen into metal carbon bonds of the BPI (1,3-bis(2-pyridylimino)isoindole) complexes [Pt(BPI)Me] and [Pd(BPI)Me] has been investigated by LED-NMR in CDCl3. The initial insertion reaction leads to peroxo complexes [Pt(BPI)OOMe] and [Pd(BPI)OOMe], which undergo further reactions over time. Spectra were recorded at 1 minute time intervals, which enabled the tracking of the methyl substituent, which eventually generates formaldehyde (and methanediol) and methanol in almost equal proportions. Degradation of the solvent CDCl3 to phosgene and DCl in the presence of oxygen and light leads to several side reactions. DCl reacts with [M(BPI)Me] and [M(BPI)OOMe] to form [M(BPI)Cl], whereas phosgene reacts with in situ generated methanol to chloro methylformate and dimethyl carbonate