High dielectric constant and high breakdown strength polyimide via tin complexation of the polyamide acid precursor

Polymer dielectrics with ultra-high charge–discharge rates are significant for advanced electrical and electronic systems. Despite the fact that polymers possess high breakdown strength, the low dielectric constant (k) of polymers gives rise to low energy densities. Incorporating metal into polyimides (PI) at the polyamic acid (PAA) precursor stage of the synthetic process is a cheap and versatile way to improve the dielectric constant of the hybrid system while maintaining a high breakdown strength. Here, we explore inclusion of different percentages of Sn as a coordinated complex in a polyimide matrix to achieve metal homogeneity within the dielectric film to boost dielectric constant. Sn–O bonds with high atomic polarizability are intended to enhance the ionic polarization without sacrificing bandgap, a measurable property of the material to assess intrinsic breakdown strength. Enhancements of k from ca. 3.7 to 5.7 were achieved in going from the pure PI film to films containing 10 mol% tin.

Polyimide with high dielectric constant and breakdown strength is synthesized via tin complexation of the polyamide acid precursor. Sn–O bonds with high atomic polarizability are intended to enhance the ionic polarization without sacrificing bandgap.     

Overexpansion of the SAPIEN 3 Transcatheter Heart Valve: An Ex Vivo Bench Study

Objectives

This study assessed the effect of overexpansion beyond labeled size (diameter) of transcatheter heart valves through an ex vivo bench study.

Immunity in young adult survivors of childhood leukemia is similar to the elderly rather than age‐matched controls: Role of cytomegalovirus

Many treatment complications that occur late in childhood cancer survivors resemble age‐related comorbidities observed in the elderly. An immune phenotype characterized by increased immune activation, systemic inflammation, and accumulation of late‐differentiated memory CD57⁺CD28^? T cells has been associated with comorbidities in the elderly. Here, we explored if this phenotype was present in young adult leukemia survivors following an average of 19 years from chemotherapy and/or radiotherapy completion, and compared this with that in age‐matched controls. We found that markers of systemic inflammation—IL‐6 and human C‐reactive protein and immune activation—CD38 and HLA‐DR on T cells, soluble CD (sCD)163 from monocytes and macrophages—were increased in survivors compared to controls. T‐cell responses specific to cytomegalovirus (CMV) were also increased in survivors compared to controls while CMV IgG levels in survivors were comparable to levels measured in the elderly (>50years) and correlated with IL‐6, human C‐reactive protein, sCD163, and CD57⁺CD28^? memory T cells. Immune activation and inflammation markers correlated poorly with prior chemotherapy and radiotherapy exposure. These data suggest that CMV infection/reactivation is strongly correlated with the immunological phenotype seen in young childhood leukemia survivors and these changes may be associated with the early onset of age‐related comorbidities in this group.     

Additive Technology: Update on Current Materials and Applications in Dentistry

Additive manufacturing or 3D printing is becoming an alternative to subtractive manufacturing or milling in the area of computer‐aided manufacturing. Research on material for use in additive manufacturing is ongoing, and a wide variety of materials are being used or developed for use in dentistry. Some materials, however, such as cobalt chromium, still lack sufficient research to allow definite conclusions about the suitability of their use in clinical dental practice. Despite this, due to the wide variety of machines that use additive manufacturing, there is much more flexibility in the build material and geometry when building structures compared with subtractive manufacturing. Overall additive manufacturing produces little material waste and is energy efficient when compared to subtractive manufacturing, due to passivity and the additive layering nature of the build process. Such features make the technique suitable to be used with fabricating structures out of hard to handle materials such as cobalt chromium. The main limitations of this technology include the appearance of steps due to layering of material and difficulty in fabricating certain material generally used in dentistry for use in 3D printing such as ceramics. The current pace of technological development, however, promises exciting possibilities.     

Characteristics of Suture Materials Used in Oral Surgery: Systematic Review

BackgroundThe aim of this review was to evaluate the most used suture materials with regards to their inflammatory response, their bacterial adhesion, and their physical properties when used to close oral wounds.MethodsFour databases (PubMed, Scopus, Dentistry & Oral Sciences, and OVID) were searched to retrieve relevant studies from January 1, 2000, to January 31, 2020.ResultsOut of the 269 articles, only 13 studies were selected as they were relevant and met the systematic review's protocol. These studies showed that almost all suture materials studies (catgut, polyglycolic acid [PGA] sutures, nylon, expanded polytetrafluoroethylene, and silk sutures) caused bacterial adherence and tissue reaction. In nylon and chromic catgut, the number of bacteria accumulated was lowest. Silk and nylon were found to be more impacted than catgut and PGA in terms of physical characteristics such as tensile strength. PGA, on the other hand, was said to be the most susceptible to knot unwinding.ConclusionsFollowing an oral surgical operation, all sutures revealed varied degrees of irritation and microbial accumulation. Nonresorbable monofilament synthetic sutures, however, exhibited less tissue response and less microbial accumulation.     

Substance P and Arg-Pro-Lys-Pro-NH-C12-H25-induced mediator release from different mast cell subtypes of rat and guinea-pig

Histamine was released from mast cells in isolated perfused heart and kidney of the rat, but not from mast cells in guinea-pig tissues, by a substance P (SP) analogue (SP(1-4)-NH-C12H25), SP(1-4)-C12 for abbreviation. This peptide also released histamine from peritoneal mast cells and basophil leucocytes of the rat. Substance P itself was compared with SP(1-4)-C12 and some structurally related peptides and showed weaker activity. SP(1-4)-C12 also released leukotrienes C4, D4, E4 and thromboxane B2 from rat heart. However, there was little effect on heart rate and force of contraction and no effect on perfusion pressure (vascular resistance) of either rat heart or kidney. The findings demonstrate the structural requirements for histamine release by SP (a possible mediator of 'neurogenic' inflammation), the metabolic energy-dependence of the release process and the functional heterogeneity and interspecies differences in mast cell populations.     

Evaluation of the effect of neoadjuvant chemotherapy on tumor and axillary lymph nodes in locally advanced breast cancer： a study of 50 patients

Objective： The purpose of the study was to correlate between effect of pre-neoadjuvant chemotherapy （NACT） and post-NACT clinical, sonographic and pathologic features of the tumor and axillary lymph nodes （ALNs） and to raise the possibility of applying the concept of sentinel lymph node biopsy （SLNB） in patients with initially positive ALNs before NACT. Methods： A prospective study of 50 female patients with locally advanced breast cancer （LABC） with clinically palpable.and cytologically （under ultrasonographic guidance） positive ALNs. All patients received NACT and then referred for ultrasono- graphic assessment of the axilla regarding any detectable sonographic criteria of metastatic deposits in ALNs as well as the tumor size in relation to its prechemotherapy size, All patients were then subjected either to modified radical mastectomy or breast conserving surgery. The clinical, sonographic and pathological response of the tumor and the ALNs were documented, classified and correlated with each other. Results： Patients＇ mean age was 47.7±9.1 years. The mean clinical tumor size was 6.7 ± 1.4 cm; stage IliA that was presented in 32 patients （64%） and IIIB was presented in 18 patients （36%）. Chemotherapy was given for a median of 4 cycles, there was reduction of the mean clinical tumor size from 6.7 ± 1.4 cm to 4.3 ± 2.7 cm （P 〈 0.001）. Clinical response was complete in 5 （10%） tumors, complete pathological tumor response （post-neoadjuvant） was detected in 6 （16%） of patients. Complete clinical nodal response （post-neoadjuvant） in 23 （46%） axillae, on sonographic assessment of the axilla, response was complete in 17 （34%） axillae. Complete pathological nodal response occurred in 16 （32%） axillae. Out of 17 axillae that showed complete sonographic response 11 axillae showed complete pathological nodal response （P 〈 0.001）. Conclusion： Formal axillary lymph node dissection can be avoided and replaced by SLNB post NACT in patients with L