Comparison of tensile strength and fracture toughness of co-bonded and cold-bonded carbon fiber laminate-aluminum adhesive joints

The purpose of this work is to compare the co-bonding vs. cold-bonding route on the adhesive joint performance of a CFRP (Carbon Fiber Reinforced Polymer) laminate–aluminum connection. In particular, the overlap shear, tensile strength and Mode I and Mode II fracture toughness will be evaluated. The adhesives for co-bonding and cold-bonding are, respectively, a thermosetting modified epoxy, unsupported structural film and a two-component epoxy adhesive, chosen as representative of applications in the high-performance/race car field. The emerging trend is that, in tensile e Mode I fracture tests, the failure path is predominantly in the composite. Mode II fracture tests instead resulted in a cohesive fracture, meaning that, under pure shear loading, the weakest link may not be the composite. The lap-shear tests are placed midway (cohesive failure for co-bonding and composite delamination for cold-bonding, respectively), probably due to the different peel stress values related to the different adhesive Young’s modulus. The exploitation of the full capacity of the adhesive joint, hence the possibility of highlighting better, different performances of co-bonding vs. cold-bonding, would require consistent improvement of the out-of-plane strength of the CFRP laminate and/or to someway redistribute the peel stress on the bondline

Black soldier fly as a New chitin source: Extraction, purification and molecular/structural characterization

Black Soldier Fly (BSF) represents a potential chitin source that has not been fully explored in terms of characterization, extraction, and purification. In this study, different chemical and enzymatic protocols with or without pre-treatment (ultrasonication and mechanochemical milling) for chitin extraction were tested. Chitin was then accurately quantified and characterized from a molecular and structural point of view by UPLC-MS, XRD, and ESEM, and compared with chitin from shrimp shells. BSF chitin was more recalcitrant than shrimp chitin during extraction and purification, due to the strong binding of chitin to proteins. Indeed, the purity of shrimp chitin was 88.3g/100g of extract, while BSF chitin purity was 47.6–79.9g/100g. Furthermore, the chitin-bound proteins had a defined amino acid composition; their binding was also confirmed by structural characterization. Therefore, the efficiency of each step of the extraction process needs to be critically evaluated to adapt the methods used for crustaceans to insect biomass

influence of material and manufacturing technology on the failure behavior of composite laminate bonded joints

Abstract The purpose of this work is to evaluate the influence of co-lamination vs. co-bonding on the failure behavior, and namely the fracture toughness, of carbon fibre reinforced (CFR) composite laminate joints in order to assess comparatively their performance. Since the strength of the laminate and ply texture are parameters affecting the strength of the joint, the comparison is extended to two different types of CFR pre-preg fibers, a satin T1100 with 2573 Nanoalloy® epoxy resin supplied by Toray and a twill T700 with ER450 toughened epoxy resin supplied by CIT, Toray group, representative of two different fields of application, racing and automotive, respectively

comparative investigation of mode i and ii fracture toughness of directly cured cfrp and co cured bonded cfrp joints

Abstract Adhesive bonding is the elective joining system between Carbon-Fiber Reinforced Polymer (CFRP) parts because, with respect to fastening, it allows a large connection area, no additional parts (hence weight saving) and no need to drill holes into the composite, that is always detrimental for the strength due to the possibility of developing damage. However, the choice of bonding CFRP should be evaluated as alternative to direct curing in terms of strength and durability, compared to cost and manufacturing time and complexity. In this work, a comparison between directly cured and co-cured, bonded CFRP is done with respect to mode I and mode II fracture toughness, in order to understand whether bonding guarantees the same performance of a co-cured composite part

On the Origin of the Early Solar System Radioactivities. Problems with the AGB and Massive Star Scenarios

Recent improvements in stellar models for intermediate-mass and massive stars are recalled, together with their expectations for the synthesis of radioactive nuclei of lifetime $\tau \lesssim 25$ Myr, in order to re-examine the origins of now extinct radioactivities, which were alive in the solar nebula. The Galactic inheritance broadly explains most of them, especially if $r$-process nuclei are produced by neutron star merging according to recent models. Instead, $^{26}$Al, $^{41}$Ca, $^{135}$Cs and possibly $^{60}$Fe require nucleosynthesis events close to the solar formation. We outline the persisting difficulties to account for these nuclei by Intermediate Mass Stars (2 $\lesssim$ M/M$_\odot \lesssim 7 - 8$). Models of their final stages now predict the ubiquitous formation of a $^{13}$C reservoir as a neutron capture source; hence, even in presence of $^{26}$Al production from Deep Mixing or Hot Bottom Burning, the ratio $^{26}$Al/$^{107}$Pd remains incompatible with measured data, with a large excess in $^{107}$Pd. This is shown for two recent approaches to Deep Mixing. Even a late contamination by a Massive Star meets problems. In fact, inhomogeneous addition of Supernova debris predicts non-measured excesses on stable isotopes. Revisions invoking specific low-mass supernovae and/or the sequential contamination of the pre-solar molecular cloud might be affected by similar problems, although our conclusions here are weakened by our schematic approach to the addition of SN ejecta. The limited parameter space remaining to be explored for solving this puzzle is discussed.Comment: Accepted for publication on Ap

Two-loop cusp anomaly in ABJM at strong coupling

We compute the null cusp anomalous dimension of ABJM theory at strong coupling up to two-loop order. This is done by evaluating corrections to the corresponding superstring partition function, weighted by the AdS 4 × ℂℙ3 action in AdS light-cone gauge. We compare our result, where we use an anomalous shift in the AdS 4 radius, with the cusp anomaly of N = 4 SYM, and extract the two-loop contribution to the non-trivial integrable coupling h(λ) of ABJM theory. It coincides with the strong coupling expansion of the exact expression for h(λ) recently conjectured by Gromov and Sizov. Our work provides thus a non-trivial perturbative check for the latter, as well as evidence for two-loop UV-finiteness and quantum integrability of the Type IIA AdS 4 × ℂℙ3 superstring in this gauge

Heterogeneity of cancer-initiating cells within glioblastoma.

Malignant gliomas, particularly glioblastoma multiforme (GBM), account for the majority of brain tumors. Their incidence is increasing world wide and they are incurable. Although a transient response to therapy is observed, tumor recurrence is inevitable and occurs within tissue that has received cytotoxic therapy. This suggests that a subpopulation of resistant cells is responsible for tumor regrowth. The treatment of GBMs represents a daunting challenge to clinicians due principally to the lack of effective therapeutic options. One explanation for this is the marked cellular and genetic heterogeneity within and across these types of tumors. Unravelling the cellular composition of gliomas and describing cell lineage relationships are essential for therapeutic breakthroughs. The recent proposal that a small percentage of cells with stem cells characteristics are responsible for tumor initiation and growth has sparked an interest in applying approaches used to study somatic stem cells toward an understanding of the cellular elements responsible for cancer progression and recurrence. To outline the relevance of these findings is the purpose of this review

NIKEL: Electronics and data acquisition for kilopixels kinetic inductance camera

A prototype of digital frequency multiplexing electronics allowing the real time monitoring of microwave kinetic inductance detector (MKIDs) arrays for mm-wave astronomy has been developed. Thanks to the frequency multiplexing, it can monitor simultaneously 400 pixels over a 500 MHz bandwidth and requires only two coaxial cables for instrumenting such a large array. The chosen solution and the performances achieved are presented in this paper.Comment: 21 pages, 14 figure

Large-sized pleomorphic adenoma of the cheek treated with Nd:Yag laser: Report of a case and review of the literature

Pleomorphic adenoma (PA) mostly involves parotid glands, while extra-parotid localizations are relatively uncommon. Particularly, PAs of the cheek minor salivary glands with a size larger than 4 cm are exceedingly rare, with only few cases reported. Surgical treatment of PA usually consists in radical excision. However, despite a presumptive radicality, recurrences, sometimes followed by malignant transformation, may occur. Here we report a case of a large-sized (6 cm) PA of the cheek minor salivary glands in a 70 year-old female patient, successfully treated through a conservative approach, based on the use of Nd:YAG Laser (λ=1064 nm). No recurrences were observed after a 2-year follow-up. A concise review of the literature, describing the features of 14 cases is also provided. Advantages of laser treatment include a precise cut, reduction of trauma on surrounding tissues, the possibility of a very good intraoperative hemostasis. Such features may sometimes allow to avoid general anesthesia, even for removal of big lesions. Post-operative course, in terms of pain and swelling, is usually better for intervention performed with laser, when compared to traditional surgery

Large-sized pleomorphic adenoma of the cheek treated with Nd:Yag laser: Report of a case and review of the literature

Pleomorphic adenoma (PA) mostly involves parotid glands, while extra-parotid localizations are relatively uncommon. Particularly, PAs of the cheek minor salivary glands with a size larger than 4 cm are exceedingly rare, with only few cases reported. Surgical treatment of PA usually consists in radical excision. However, despite a presumptive radicality, recurrences, sometimes followed by malignant transformation, may occur. Here we report a case of a large-sized (6 cm) PA of the cheek minor salivary glands in a 70 year-old female patient, successfully treated through a conservative approach, based on the use of Nd:YAG Laser (λ=1064 nm). No recurrences were observed after a 2-year follow-up. A concise review of the literature, describing the features of 14 cases is also provided. Advantages of laser treatment include a precise cut, reduction of trauma on surrounding tissues, the possibility of a very good intraoperative hemostasis. Such features may sometimes allow to avoid general anesthesia, even for removal of big lesions. Post-operative course, in terms of pain and swelling, is usually better for intervention performed with laser, when compared to traditional surgery