Homogenization of diffuse delamination in composite laminates

Diffuse delamination induced by transverse cracking is usually the secondary damage mode when a composite laminate experiences tensile loading. The fist damage mechanism in such a laminate is transverse cracking which has been widely investigated with both analytical methods and " mechanism-based" constitutive laws. Delamination induced by matrix cracking is already studied extensively by analytical approaches, however, a proper homogenization way has not been proposed yet. In this paper, a modification to an available cohesive constitutive law is proposed which is capable of considering the effect of diffuse delamination without the necessity of consideration of an actual discontinuity between the layers. The proposed constitutive law is then compared against its equivalent models containing interlaminar discontinuity and it is shown that the obtained results from both models are in good. Then the proposed modification is used in Double Cantilever Beam (DCB) specimen and the obtained results are found coincident with the equivalent model with diffuse discontinuities at the interface. Finally, a damaged cross-ply laminate is modeled under the boundary conditions of tensile loading and also 3-point bending with and without the proposed cohesive modification. In tensile loading, the results of both cases are similar; however, it is shown that in bending, the unmodified cohesive law predicts the lateral stiffness larger than the proposed modification. The lateral stiffness of the equivalent model with discontinuities as crack indicates that the proposed modification is able to properly consider the lateral stiffness decrease

Layer-By-Layer Assembly of Graphene Oxide on Thermosensitive Liposomes for Photo-Chemotherapy

Stimuli responsive polyelectrolyte nanoparticles have been developed for chemo-photothermal destruction of breast cancer cells. This novel system, called layer by layer Lipo-graph (LBL Lipo-graph), is composed of alternate layers of graphene oxide (GO) and graphene oxide conjugated poly (l-lysine) (GO-PLL) deposited on cationic liposomesencapsulating doxorubicin. Various concentrations of GO and GO-PLL were examined and the optimal LBL Lipo-graph was found to have a particle size of 267.9 ± 13 nm, zeta potentialof +43.9 ± 6.9 mV and encapsulation efficiency of 86.4 ± 4.7%. The morphology of LBL Lipo-graph was examined by cryogenic-transmission electron microscopy (Cryo-TEM), atomic force microcopy (AFM) and scanning electron microscopy (SEM). The buildup of LBL Lipo-graph was confirmed via ultraviolet-visible (UV–Vis) spectrophotometry, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis. Infra-red (IR) response suggests that four layers are sufficient to induce a gel-to-liquid phase transition in response to near infra-red (NIR) laser irradiation. Light-matter interaction of LBL Lipo-graph was studied by calculating the absorption cross section in the frequency domain by utilizing Fourier analysis. Drug release assay indicates that the LBL Lipo-graph releases much faster in an acidic environment than a liposome control. A cytotoxicity assay was conducted to prove the efficacy of LBL Lipo-graph to destroy MD-MB-231 cells in response to NIR laser emission. Also, image stream flow cytometry and two photon microcopy provide supportive data for the potential application of LBL Lipo-graph for photothermal therapy. Study results suggest the novel dual-sensitive nanoparticles allow intracellular doxorubin delivery and respond to either acidic environments or NIR excitation. Statement of Significance Stimuli sensitive hybrid nanoparticles have been synthesized using a layer-by-layer technique and demonstrated for dual chemo-photothermal destruction of breast cancer cells. The hybrid nanoparticles are composed of alternating layers of graphene oxide and graphene oxide conjugated poly-l-lysine coating the surface of a thermosensitive cationic liposome containing doxorubicin as a core. Data suggests that the hybrid nanoparticles may offer many advantages for chemo-photothermal therapy. Advantages include a decrease of the initial burst release which may result in the reduction in systemic toxicity, increase in pH responsivity around the tumor environment and improved NIR light absorption

Numerical modeling of diffuse transverse cracks and induced delamination using cohesive elements

This article is devoted to the modeling of spread kind of damages such as matrix cracking and induced delamination in symmetric and asymmetric cross-ply laminates of composite materials using cohesive elements. For matrix crack modeling, parallel rows of cohesive elements are used between every row of 2D elements in 90° layers. Delamination is also modeled by cohesive elements at the 90°/0° interface. Since matrix cracking is a diffuse kind of damage mechanism, application of cohesive elements is not straightforward, and special techniques are necessary to resolve the modeling difficulties. For this purpose, two techniques of "bisecting" and "random distribution of strength of cohesive elements" are proposed here. Both techniques are applied to various symmetric laminates of [0/903]s and [90n/0]s (n=1 to 3). The predicted stiffness and damage progresses from both techniques are in good agreement with the experimental results. Then, asymmetric cross-ply laminates of [90n/0] (n=1 to 3) are analyzed to show the capability of this method in progressive damage analyses. The proposed method is less restricted in comparison with available micromechanical methods and is able to predict damage initiation, propagation and damage-mode transition for any symmetric and asymmetric cross-ply sequence. Therefore, this method can be used for development of "in-plane damage" of constitutive laws especially when specimens are subjected to complex loading and boundary conditions

Experimental and numerical study of oblique transverse cracking in cross-ply laminates under tension

The first damage mode in cross-ply laminates under tension is broadly accepted as transverse cracks normal to the loading direction in the 90° layers, but there is not the same agreement about the second damage mode. While most of the analytical and experimental results are based on delamination induced by transverse cracking, another type of damage, oblique cracks within the 90° layers, has also been observed as the second damage mode in [0/904]s laminates. To understand the cause of this phenomenon, FE analyses considering damage development at the interfaces were performed. The obtained results indicate that the main reason for the oblique cracking damage mode is the higher toughness of the material in mode-II compared with mode-I: when the value of shear toughness is close to the opening toughness, the second damage mode in cross-ply laminates under tensile loading is delamination induced by transverse cracks, however, if the difference between the two values is large, oblique cracks in the 90°layers are likely to appear. In the specific tested and analysed laminate, if the mode II toughness is double the mode I toughness, oblique cracking occurs but if the values of mode I and mode II toughness are close, delamination is the second damage mode

The inter relationships among growth parameters (weight, height) and ectopic eruption of permanent first molars of children aged 6-9 years in Kerman, Iran

BACKGROUND AND AIM: Ectopic eruption (EE) of the permanent first molars (PFMs) results from a discrepancy between the jaw growth rate and the growth rate of these teeth. The present study was undertaken to evaluate the prevalence of EE of PFMs in Kerman, Iran, and then determine the relationship between growth parameters (height and weight) and this developmental anomaly. METHODS: In the present study, 2025 children aged 6-9 years were examined to determine the prevalence of eruption of PFMs. Examinations were carried out with the use of tongue depressors under adequate light. Height and weight were determined in the control (without EE of PFM) and the case (with EE of PFM) groups, and then registered in the relevant checklist. Descriptive statistical methods were used for the analysis of qualitative data at a confidence interval (CI) of 95%. Chi-squared test was used for comparisons between the two groups in relation to age and gender. RESULTS: In the present study, prevalence of the EE of PFMs was 2.8% in 6 to 9-year-old children in Kerman. The rate of this developmental anomaly was higher in boys compared to girls and higher in the maxilla than in the mandible; however, the differences were not significant (P > 0.05). The prevalence of EE was higher in children with a lower mean age and a lower mean height and weight, which was significant statistically (P 0.05). In addition, there was no significant relationship between cleft palate or lip and EE (P > 0.05). CONCLUSION: Children in the lower than normal height and weight percentile are more susceptible to the EE developmental anomaly. KEYWORDS: Height; Weight; Ectopic Eruptio

Experimental investigation of low-level water in waste-oil produced biodiesel-diesel fuel blend

Diminishing fuel resources and stringent emission mandates have demanded cleaner combustion and increased fuel efficiency. Three water addition rates, i.e., 2, 4, and 6 wt% in biodiesel-diesel blend (B5) was investigated herein. Combustion characteristics of the emulsified fuel blends were compared in a naturally-aspirated diesel engine at full load and different engine speeds. More specifically, biodiesel was produced from waste cooking oil (WCO) and to further increase waste utilization, recycled biodiesel wastewater was used as additive in B5. The result obtained showed that low-level water addition (i.e., 2 and 4 wt%) in B5 led to different results from those obtained using higher water addition rates (i.e., >5 wt%) reported by the previous studies. In more details, the findings of the present study revealed that low level water addition in B5 could considerably reduce CO, HC, CO2, and NOx emissions. Among water-containing B5 fuel emulsions, the optimal water addition level in terms of engine performance parameters and emissions was found at 4 wt%. In particular, the emitted CO2, HC, and NOx were decreased by over 8.5%, 28%, and 24%, respectively, at maximum speed of 2500 rpm

Ocean remote sensing techniques and applications: a review (Part II)

As discussed in the first part of this review paper, Remote Sensing (RS) systems are great tools to study various oceanographic parameters. Part I of this study described different passive and active RS systems and six applications of RS in ocean studies, including Ocean Surface Wind (OSW), Ocean Surface Current (OSC), Ocean Wave Height (OWH), Sea Level (SL), Ocean Tide (OT), and Ship Detection (SD). In Part II, the remaining nine important applications of RS systems for ocean environments, including Iceberg, Sea Ice (SI), Sea Surface temperature (SST), Ocean Surface Salinity (OSS), Ocean Color (OC), Ocean Chlorophyll (OCh), Ocean Oil Spill (OOS), Underwater Ocean, and Fishery are comprehensively reviewed and discussed. For each application, the applicable RS systems, their advantages and disadvantages, various RS and Machine Learning (ML) techniques, and several case studies are discussed.Peer ReviewedPostprint (published version

Eryngium Billardieri Induces Apoptosis via Bax Gene Expression in Pancreatic Cancer Cells

Purpose: Pancreatic adenocarcinoma has a high prevalence all over the world. Most of the therapeutic approaches failed as a result of tumor invasion and rapid metastasis. Several natural plants have been shown to have promising therapeutic effects. Thus, the aim of this study was to investigate the cytotoxic activity of Eryngium billardieri against PANC-1 cancer cell lines. Methods: Dimethylthiazole diphenyltetrazolium bromide assay (MTT assay) and flow cytometry were used to assess the cytotoxicity of E. billardieri extracts against PANC-1 cancer cell lines. Quantitative Polymerase Chain Reaction (qPCR) was conducted to investigate the expression levels of Bcl2- associated X protein (BAX) and cyclin D1. Results: The results of the MTT assay showed that E. billardieri extracts had cytotoxic effects on PANC- 1 cancer cell lines. Moreover, the findings from the gene expression confirmed the over expression of Bax, and under expression of cyclin D1 following treatment with dichloromethane (DCM) and n-hexane (n- hex) extracts in cancer cells (P < 0.05). Interestingly, the flow cytometry results showed that DCM and n- hex extracts of E. billardieri induced apoptosis in PANC- 1 cancer cell lines. Conclusion: The results of this study demonstrated that DCM and n- hex extracts of E. billardieri significantly induce apoptosis by increasing Bax and decreasing cyclin D1 mRNA expression. Therefore, E. billardieri may be regarded as a novel approach for treatment of pancreatic cancer as a result of its promising apoptotic and cytotoxic properties

Bi-allelic ACBD6 variants lead to a neurodevelopmental syndrome with progressive and complex movement disorders

The acyl-CoA-binding domain-containing protein 6 (ACBD6) is ubiquitously expressed, plays a role in the acylation of lipids and proteins, and regulates the N-myristoylation of proteins via N-myristoyltransferase enzymes (NMTs). However, its precise function in cells is still unclear, as is the consequence of ACBD6 defects on human pathophysiology. Utilizing exome sequencing and extensive international data sharing efforts, we identified 45 affected individuals from 28 unrelated families (consanguinity 93%) with bi-allelic pathogenic, predominantly loss-of-function (18/20) variants in ACBD6. We generated zebrafish and Xenopus tropicalis acbd6 knockouts by CRISPR/Cas9 and characterized the role of ACBD6 on protein N-myristoylation with YnMyr chemical proteomics in the model organisms and human cells, with the latter also being subjected further to ACBD6 peroxisomal localization studies. The affected individuals (23 males and 22 females), with ages ranging from 1 to 50 years old, typically present with a complex and progressive disease involving moderate-to-severe global developmental delay/intellectual disability (100%) with significant expressive language impairment (98%), movement disorders (97%), facial dysmorphism (95%), and mild cerebellar ataxia (85%) associated with gait impairment (94%), limb spasticity/hypertonia (76%), oculomotor (71%) and behavioural abnormalities (65%), overweight (59%), microcephaly (39%) and epilepsy (33%). The most conspicuous and common movement disorder was dystonia (94%), frequently leading to early-onset progressive postural deformities (97%), limb dystonia (55%), and cervical dystonia (31%). A jerky tremor in the upper limbs (63%), a mild head tremor (59%), parkinsonism/hypokinesia developing with advancing age (32%), and simple motor and vocal tics were among other frequent movement disorders. Midline brain malformations including corpus callosum abnormalities (70%), hypoplasia/agenesis of the anterior commissure (66%), short midbrain and small inferior cerebellar vermis (38% each), as well as hypertrophy of the clava (24%) were common neuroimaging findings. acbd6-deficient zebrafish and Xenopus models effectively recapitulated many clinical phenotypes reported in patients including movement disorders, progressive neuromotor impairment, seizures, microcephaly, craniofacial dysmorphism, and midbrain defects accompanied by developmental delay with increased mortality over time. Unlike ACBD5, ACBD6 did not show a peroxisomal localisation and ACBD6-deficiency was not associated with altered peroxisomal parameters in patient fibroblasts. Significant differences in YnMyr-labelling were observed for 68 co- and 18 post-translationally N-myristoylated proteins in patient-derived fibroblasts. N-Myristoylation was similarly affected in acbd6-deficient zebrafish and Xenopus tropicalis models, including Fus, Marcks, and Chchd-related proteins implicated in neurological diseases. The present study provides evidence that bi-allelic pathogenic variants in ACBD6 lead to a distinct neurodevelopmental syndrome accompanied by complex and progressive cognitive and movement disorders