Foams with enhanced ductility and impact behavior based on polypropylene composites

Producción CientíficaIn this work, formulations based on composites of a linear polypropylene (L-PP), a long-chain branched polypropylene (LCB-PP), a polypropylene–graft–maleic anhydride (PP-MA), a styrene-ethylene-butylene-styrene copolymer (SEBS), glass fibers (GF), and halloysite nanotubes (HNT-QM) have been foamed by using the improved compression molding route (ICM), obtaining relative densities of about 0.62. The combination of the inclusion of elastomer and rigid phases with the use of the LCB-PP led to foams with a better cellular structure, an improved ductility, and considerable values of the elastic modulus. Consequently, the produced foams presented simultaneously an excellent impact performance and a high stiffness with respect to their corresponding solid counterparts.Unión Europea (Evolution project under grant 314744)Ministerio de Ciencia, Innovación y Universidades - Fondo Europeo de Desarrollo Regional (project RTI2018-098749-B-I00)Junta de Castilla y Leon (project VA275P18

Morphological and Tribological Properties of PMMA/Halloysite Nanocomposites

From an environmental and cost-effective perspective, a number of research challenges can be found for electronics, household, but especially in the automotive polymer parts industry. Reducing synthesis steps, parts coating and painting, or other solvent-assisted processes, have been identified as major constrains for the existing technologies. Therefore, simple polymer processing routes (mixing, extrusion, injection moulding) were used for obtaining PMMA/HNT nanocomposites. By these techniques, an automotive-grade polymethylmethacrylate (PMMA) was modified with halloysite nanotubes (HNT) and an eco-friendly additive N,N′-ethylenebis(stearamide) (EBS) to improve nanomechanical properties involved in scratch resistance, mechanical properties (balance between tensile strength and impact resistance) without diminishing other properties. The relationship between morphological/structural (XRD, TEM, FTIR) and tribological (friction) properties of PMMA nanocomposites were investigated. A synergistic effect was found between HNT and EBS in the PMMA matrix. The synergy was attained by the phase distribution resulted from the selective interaction between partners and favourable processing conditions. Modification of HNT with EBS improved the dispersion of nanoparticles in the polymer matrix by increasing their interfacial compatibility through hydrogen bonding established by amide groups with aluminol groups. The increased interfacial adhesion further improved the nanocomposite scratch resistance. The PMMA/HNT-EBS nanocomposite had a lower coefficient of friction and lower scratch penetration depth than PMMA/HNT nanocomposite.Financial support by the EU Commission through Project H2020-686165-IZADINANO2INDUSTRY is gratefully acknowledged

Poly(vinyl acetate)–clay hybrids prepared via emulsion polymerization, assisted by a nonionic surfactant

Hybrid materials containing poly(vinyl acetate) and montmorillonite (MMT) were prepared using an one-batch emulsion polymerization recipe, assisted by a nonionic surfactant. To explain the results of our experiments, a thorough investigation of the specific interactions between the compounds was done, in the wet as well as the dried state of the end-products. In dispersion, polymer–surfactant interactions were found to be driven by hydrophobic coupling into superficial (mixt) admicelles. Another important finding is that the amount of clay used in the recipes and its relative concentration with respect to the other reaction partners influences drastically the morphological units in the end-products. For low [MMT], well-defined, spherical particles are formed. At the other extreme, for high [MMT], production of polymeric, water-swollen aggregates is favored. A small amount of reformed MMT tactoids was detected in all casted hybrid films, indicating that most of the inorganic is dispersed in the organic phase

The Effect of SEBS/Halloysite Masterbatch Obtained in Different Extrusion Conditions on the Properties of Hybrid Polypropylene/Glass Fiber Composites for Auto Parts

Masterbatches from a linear poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS) and halloysite nanotubes (HNT-QM) were obtained in different conditions of temperature and shear using two co-rotating twin-screw extruders. The influence of screw configuration and melt processing conditions on the morpho-structural, thermal and mechanical properties of masterbatches at macro and nanoscale was studied. A good dispersion of halloysite nanotubes and better thermal stability and tensile and nanomechanical properties were obtained at a lower temperature profile and higher screw speed. The effect of masterbatches, the best and worst alternatives, on the properties of a polypropylene (PP)–glass fiber (GF) composite was also evaluated. Double hardness, tensile strength and modulus and four times higher impact strength were obtained for PP/GF composites containing masterbatches compared to pristine PP. However, the masterbatch with the best properties led further to enhanced mechanical properties of the PP/GF composite. A clear difference between the effects of the two masterbatches was obtained by nanoindentation and nanoscratch tests. These analyses proved to be useful for the design of polymer composites for automotive parts, such as bumpers or door panels. This study demonstrated that setting-up the correct processing conditions is very important to obtain the desired properties for automotive applications

Bilateral breast carcinoma – a study of patients admitted in a university emergency hospital

Introduction. Breast carcinoma represents the leading cause of oncologic mortality among women worldwide. Bilateral breast carcinoma is a distinct pathologic entity, with particular prognostic and therapeutic implications. Objective. The objective of the study was to determine the histologic and immunohistochemical characteristics of patients with bilateral breast carcinoma admitted in a university emergency hospital from Bucharest, Romania. Materials and methods. We analyzed breast carcinoma specimens registered as bilateral in the Department of Pathology of the University Emergency Hospital, Bucharest, Romania, between 2015‑2017, and studied their histologic and molecular features in the clinical context obtained from our hospital database. Results. All the analyzed patients were postmenopausal women. The extent of time between the diagnosis of the first and second tumor varied in metachronous cases from 8 months to 7 years. In the majority of cases, the bilateral breast lesions shared histologic, grading and hormone expression similarities. Conclusions. Bilateral breast carcinoma is a rare entity that needs more histologic parameters to be defined as primary or metastatic

High-grade versus low-grade serous carcinoma of the ovary – current differential diagnosis and perspectives

Introduction. Serous carcinoma is responsible for 47% of all ovarian cancers, and from these cases, only 5% are represented by low-grade serous carcinoma, the rest of them accounting for high-grade serous carcinoma. Objective. The aim of this study is an observational approach of the differences and similarities of the two types of serous carcinoma of the ovary, that must be seen as different forms of cancer and rendered with care. Methods. We performed a retrospective study using three cases of ovarian high-grade serous carcinoma and three cases of ovarian low-grade serous carcinoma, diagnosed at the University Emergency Hospital Bucharest. We analyzed patients’ age, clinical symptoms, macroscopic and microscopic features together with immunohistochemistry tests. Results. Mean age for HG carcinoma was 71.3 years old and for LG carcinoma 47.6 years old. Average tumor diameter was with 5.67 cm higher for LG carcinoma. The most encountered stage for HG tumors was pT2a and for LG tumors was pT1a. Mean value for Ki67 was with 36.33% higher for HG carcinoma. AR expressed diffuse positivity in two cases of LG and only focal positivity in two cases of HG. CD44 expressed focal positivity in all cases of LG and had different patterns in HG. Conclusions. We found considerable differences between patients’ mean age, macroscopic and microscopic features, together with immunohistochemistry expression for Ki67, AR, CD44

Synthesis and characterization of cellulose acetate-hydroxyapatite micro and nano composites membranes for water purification and biomedical applications

In this work, we report facile synthesis and characterization of new cellulose acetate-hydroxyapatite membranes for water purification and biomedical applications. The membranes were synthesized from a polymer solution in N, N’-dimethylformamide (12% wt.) where different concentrations of hydroxyapatite (1, 2, 4% wt. based on the amount of polymer) were dispersed using sonication. The synthesis of membranes was carried out by precipitation employing phase inversion using deionized water. The morphological and structural characterization of the synthesized membranes was carried out using SEM, EDS and FT-IR. Thermal characterization (TGA & DTG) and water flows analysis of the synthesized membranes was also carried out. The SEM analysis confirmed the presence of hydroxyapatite micro/nanostructured particles in the membrane as well as significant changes in the morphology of the membranes surface. The presence of inorganic compounds was also found to influence the thermal or hydrodynamic properties of the composite membranes, leading to a more stable hydrodynamic behavior, flow variation in time being much lower compared to the control membrane of cellulose acetate

The clinical importance of PD‑L1 and PD‑1 expression in diffuse large B cell lymphoma

Introduction. The target pathway programmed cell death‑1 (PD‑1)/ programmed death‑ligand 1 (PD‑L1) shows clinical efficacy in solid tumors, but also in Hodgkin’s and non‑Hodgkin’s lymphoma. PD‑L1 expression most often correlates with a poor prognosis and a PD‑1 regulatory factor that mediates immunosuppression. The presence of an increased number of tumor‑infiltrating lymphocytes (TILs) PD‑1 + is a favorable prognostic factor in patients with diffuse large B cell lymphomas (DLBCLs) and follicular lymphomas, while the low number of TILs PD‑1 + is associated with an increased risk of histological transformation. In DLBCLs, TILs PD‑1 + may not reflect the depletion of T‑mediated tumor cells but may be an indicator of lymphoid cell origin. Objectives. The objective of this study was to describe the correlation between PD‑1 and PDL‑1 with survival in patients with the diagnosis of diffuse large B cell lymphoma. Material and methods. We have studied 80 patients and we have analyzed DLBCLs according to the Hans algorithm; in addition, we analyzed PD‑1 and PD‑L1 in tumor cells and in immune cells and we correlated this data with patient’s survival. Results. We found that there is a tendency of decreased survival and therapeutic response in DLBCL patients, with both an intense and weak PD‑L1 positivity in tumor cells. PD‑1 low positivity was associated in higher percentage with relapse and treatment unresponsiveness. Conclusions: Our data suggested that PD‑L1 expression correlates with a poor clinical response although it is not an independent prognostic marker and PD‑1 represents a favorable prediction factor for survival

Clinico‑morphological aspects and new immunohistochemistry characteristics of ovarian high‑grade serous carcinoma

Introduction. High‑grade serous carcinoma of the ovary is an aggressive form of cancer, with unknown precursor lesions and often delayed diagnosis because of non‑specific, mild symptoms. Objective. We performed a clinical‑pathological study of ovarian high‑grade serous carcinomas, in order to evaluate morphological and new immunohistochemistry characteristics of this malignancy. Methods. This is a retrospective study of 10 cases of ovarian high‑grade serous carcinoma. We evaluated patients’ age, symptoms at presentation, macroscopic aspects, bilateral involvement, microscopic features: papillary/solid areas, mitotic index, psammoma bodies, tumoral extension, lymph node metastasis, immunohistochemistry markers: CD44, ER, AR, Ki67 index. Results. Mean age was 56.9 years old. Tumors were bilateral in 50% of cases. Only 30% were limited to the ovary. Maximum tumor diameter was 16 cm. Solid component in a proportion of 50‑95% was more characteristic. Most tumors had a mitotic index of 30‑50 mitosis/10HPF (70% of cases). 20% of cases contained psammoma bodies. 2 cases out of 7 had lymph node metastasis. We noticed one case with pleural metastasis (M1). We observed AR80% was noticed in 30% of cases. CD44 was positive in 50% of cases and one case had diffuse positivity of CD44 in corpus luteum cells near the tumoral bed. Conclusions. The majority of patients with ovarian high‑grade serous carcinomas presented with extraovarian extension and were characterized by high mitotic index, rare presence of psammoma bodies, AR expression <10%, novel marker CD44 positive in 50% of cases and curious positivity in corpus luteum cells associated with the tumor

TITANIUM FUNCTIONALIZING AND DERIVATIZING FOR IMPLANTABLE MATERIALS OSSEOINTEGRATION PROPERTIES ENHANCING

The article focuses on titanium functionalizing and derivatizing reactions for implantable materials osseointegration properties enhancing. Thus, the titanium dioxide was activated to the titanium hydroxide (functionalization), being further immobilized on the titanium surface by ethanolamine covalent reactions and (3-aminopropyl)triethoxysilane (APTS) for the osseointegration membranes reactive coating. The derivatizing was based on ether forming reactions between hydroxyl group from the titanium hydroxide surface and the ethanolamine hydroxyl groups and hydrolyzed APTS respectively. The obtained materials were characterized by scanning electron microscopy, FT-IR infrared spectroscopy, contact angle and X-Ray fluorescence