Mechanical Behaviour of Aluminium-Timber Composite Connections with Screws and Toothed Plates

This paper presents an investigation of the load-slip behaviour of aluminium-timber composite connections. Toothed plates with bolts are often used for connecting timber structural members with steel structural members. In this paper, toothed plates (C2-50/M10G, C2-50/M12G or C11-50/M12) have been used as reinforcement in aluminium-timber screwed connections for the first time. The push-out test specimens consisted of laminated veneer lumber slabs, aluminium alloy beams, and hexagon head wood screws (10 mm × 80 mm and 12 mm × 80 mm). Of the specimens, 12 additionally had toothed plates as reinforcement, while 8 had no reinforcement. The load carrying-capacity, the mode of failure and the load-slip response of the strengthened and non-strengthened screwed connections were investigated. The use of toothed plate connectors was found to be effective in increasing the strength of aluminium-timber composite connections and ineffective in improving their stiffness. The examined stiffness and strength of the connections can be used in the design and numerical modelling of aluminium-timber composite beams with reinforced screwed connections.     

Comparison of Numerical Simulation Techniques of Ballistic Ceramics under Projectile Impact Conditions

This article presents an analysis of the effectiveness of available numerical techniques in mapping the characteristic behavior of ballistic ceramics under projectile impact conditions. As part of the work, the ballistic tests were performed on the layered ceramic/steel composite armor and tested with the 7.62 × 39 mm, armor-piercing incendiary (API) BZ projectile. The experimental tests were then mapped using computer simulations. In numerical analyses, four different techniques were used to describe cubic ceramic tiles Al₂O₃ placed on the ARMOX 500T steel backing plate, i.e.,: the Finite Element Method without Erosion (FEM), Finite Element with erosion (FEM + Erosion), Smoothed Particles Hydrodynamics (SPH) and a hybrid method that converts finite elements to SPH particles after exceeding the defined failure criteria (FEM to SPH conversion). The effectiveness of the individual methods was compared in terms of quality (mapping of characteristic phenomena occurring during the penetration process), quantity (bulge height of the backing plate) and time needed to complete the calculations. On the basis of the results of the experiments and numerical simulations, it was noticed that the most accurate reproduction of the phenomenon of ballistic impact of AP projectiles on ceramic/steel composite armor can be obtained by using a hybrid method, incorporating the conversion of finite elements into SPH particles. This method should be used in cases where accuracy of the results is more important than the time required to complete the calculations. In other situations where the purpose of the calculation is not to determine, for example, the exact value of penetration depth but only to observe a certain trend, the FEM method with defined erosion criteria (variant 2), which is more than 10 times faster, can be successfully used.     

Curcumin May Prevent Basement Membrane Disassembly by Matrix Metalloproteinases and Progression of the Bladder Cancer

Authors present a review of crucial mechanisms contributing to the invasion of the basement membrane (BM) of the urothelium by cancer cells and to the progression of bladder cancer (BC). The breeching of the urothelial BM, facilitated by an aberrant activation of matrix metalloproteinases (MMP) is particularly perilous. Inhibition of activation of these proteinases constitutes a logic opportunity to restrain progression. Because of limited efficacy of current therapeutic methods, the search for the development of alternative approaches constitutes “the hot spot” of modern oncology. Recent studies revealed significant anticancer potential of natural phytochemicals. Especially, curcumin has emerged as a one of the most promising phytochemicals and showed its efficacy in several human malignancies. Therefore, this article addresses experimental and clinical data indicating multi-directional inhibitory effect of curcumin on the growth of bladder cancer. We particularly concentrate on the mechanisms, by which curcumin inhibits the MMP’s activities, thereby securing BM integrity and alleviating the eventual cancer invasion into the bladder muscles. Authors review the recently accumulating data, that curcumin constitutes a potent factor contributing to the more effective treatment of the bladder cancer.     

Sense of taste in patients after cochlear implantation-preliminary study

BackgroundTaste is the leading sense in how we determine the quality of consumed food. Proper gustatory sensation largely determines the well-being and health of an organism, and this affects their quality of life.ObjectivesThe aim of the present study was to estimate the risk of early taste disorders following implantation surgery.MethodsTwenty patients underwent a taste test before, 1 day after, and 1 month after cochlear implantation. The taste sensations of sweet, sour, salty, and bitter were determined.ResultsStatistical analysis showed no significant differences (p > 0.05) between individual tests among the entire study group. After dividing the respondents into smoking (n=6) and non-smoking (n=14) groups, only a weak correlation (p = 0.043) was found between the results of the first and second examination in the smoker group. However, a statistically significant decrease in the number of saline-sensitive (p<0.001) and acid-sensitive (p = 0.042) subjects was observed.ConclusionThese findings suggest that people after a cochlear implant may have transient taste disorders. Taste disorder called dysgeusia may be an early complication after the implantation procedure contributing to deterioration of patients quality of life.     

Synthesis of xanthohumol and xanthohumol-d3 from naringenin

A six-step synthesis of xanthohumol (1a) and its d₃-derivative (1b) from easily accessible naringenin is reported. The prenyl side chain was introduced by Mitsunobu reaction followed by the europium-catalyzed Claisen rearrangement and base-mediated opening of chromanone gave access to an α,β-conjugated ketone system. Compound 1b was used as an internal standard in stable isotope dilution assays of 1a in two Polish beers.

A six-step synthesis of xanthohumol and its d₃-derivative from easily accessible naringenin is reported.

Xanthohumol (1a, Scheme 1A) is a naturally occurring prenylated chalcone produced by lupulin glands in female inflorescences of hop plants.¹ In recent years, 1a has attracted significant attention due to its vast range of biological activities including cancer-preventive, antioxidative, anti-inflammatory, and antiviral.^2–8 Such properties combined with low toxicity to the human body make 1a a prospective therapeutic agent, diet supplement, or ingredient of cosmetics.⁹ Although 1a was isolated from natural sources in 1913,¹⁰ the first synthesis of this compound was reported as late as in 2007.¹¹ Several other syntheses have been reported since then, but only minor improvements have been achieved.^12–14Open in a separate windowScheme 1The background of the study.Bioactive compounds labeled with stable isotopes (deuterium, carbon-13) are widely applied in metabolomic studies for tracking metabolic pathways and as internal standards in stable isotope dilution assays.^15,16 Deuterated compounds are also considered as attractive drug candidates due to the influence of the kinetic isotope effect on pharmacokinetics.^17–19 Although approaches to ¹³C-enriched xanthohumol^20,21 and hydrogen/deuterium exchange in 1a²² were reported, no scalable and cost-effective synthesis of the deuterium-labeled derivative of 1a (i.e.1b) has been disclosed to date.Two main challenges have to be faced in the synthesis of 1a: (i) construction of a pentasubstituted aromatic ring containing a prenyl side chain and (ii) selection of suitable protecting groups for phenols. In the case of (i), phloroglucinol is used as a precursor and an acyl-substituent is introduced by Friedel–Crafts acylation with a subsequent Claisen–Schmidt condensation. The prenyl side-chain is introduced by Mitsunobu alkylation, followed by Claisen rearrangement. In the case of (ii), acid-sensitive alkoxymethyl protecting groups, removable under conditions in which 1a does not cyclize to isoxanthohumol (2a), are used most often (Scheme 1A).In this study, we have developed a synthetic approach for the formation of 1a and its deuterated analog 1b. We envisioned that both 1a and 1b can be directly obtained by the base-promoted chromanone ring-opening of 2a or 2b, which in turn can be obtained from easily accessible naringenin (3) (ca. 1 $/1 g) via two-step prenylation and Williamson etherification of the phenolic OH (Scheme 1B). The use of 3 as the starting material is beneficial as only one prenyl substituent has to be introduced.The synthetic route leading to 1a and 1b is depicted in Scheme 2. Our synthesis commenced from naringenin (3), which was selectively converted to diester 4 (Ac₂O, pyridine). O-Alkylation of 4 under Mitsunobu conditions (3-methyl-2-butene-1-ol, Ph₃P, DIAD), followed by the catalytic Claisen rearrangement of 5 (Eu(fod)₃, 1,2-dichloroethane, 80 °C) afforded prenyl-derivative 6. Notably, performing the latter reaction in 1,2-dichloroethane above its boiling point was superior in comparison to earlier reports.^23–26 Alkylation of 6 (CH₃I, Ag₂O or CD₃I, Ag₂O) afforded 7a/7b in good yields. An alternative approach to 7b involving the alkylation of phenolic OH under Mitsunobu conditions (CD₃OD, Ph₃P, DIAD) required a large excess of reagents and afforded the product in moderate yield. Basic hydrolysis (KOH, MeOH) of esters afforded isoxanthohumols 2a/2b. Although the chromane ring was stable during the hydrolysis, it could be opened under more harsh conditions (DBU, DMF, 70 °C),^27,28 leading to 1a/1b in good yields after a mild acidic workup.Open in a separate windowScheme 2The synthetic route to 1a and 1b.With 1a and 1b in hand, we investigated their MS-fragmentation patterns in electrospray ionization in positive and negative ion modes. The MRM transitions were found by an automatic procedure and they are listed in † for details). In positive ion mode, the most intensive product ions in fragmentation of 1a were ions with m/z values of 178.9, 299.0, 113.0, and 150.9. Corresponding ions with m/z +3 values can be found in the fragmentation of 1b. On the other hand, in the negative ion mode, the same product ions are observed both in the case of 1a and 1b, indicating that the CH₃/CD₃ groups were lost during fragmentations.The MRM transitions of 1a and 1b

Structure and Properties of Gas-Nitrided,Precipitation-Hardened Martensitic Stainless Steel

Nanoflex stainless steel is a promising material for medical applications. However, improvement of its mechanical properties without compromising its corrosion resistance is still a challenge. In order to investigate the effect of the nitriding process on the corrosion and wear resistance of Sandvik Nanoflex^TM steel, a number of processes were carried out in a gas atmosphere with differing ammonia contents in the temperature range of 425–475 °C for 4 h. The mechanical properties and wear resistance of the layers were tested using the nanoindentation and pin-on-disc methods, respectively. In order to assess corrosion resistance, potentiodynamic tests were carried out in Ringer’s artificial body fluid and in a 3% aqueous solution of sodium chloride. The results are discussed herein with respect to the microstructural characteristics of the layers studied using light and scanning electron microscopy, X-ray diffraction phase analysis and wavelength dispersive X-ray microanalysis. The structure of nitrided layers included three zones: the subsurface zone composed of nitrides and the zones composed of metastable phases, i.e., the S phase (γN) and expanded martensite (αN) with possible precipitates of nitrides. The third zone adjacent to the steel core was enriched with carbon. The nitrided samples showed significant improvement in the wear rate while maintaining good corrosion resistance in comparison to the non-treated steel. We concluded that nitriding should be carried out at a temperature below 450 °C and in an atmosphere containing no more than approximately 50% ammonia in order to avoid nitrides precipitation.     

Can Diet Prevent Urological Cancers? An Update on Carotenoids as Chemopreventive Agents

Urological cancers, namely prostate, bladder, kidney, testicular, and penile cancers, are common conditions that constitute almost one-quarter of all malignant diseases in men. Urological cancers tend to affect older individuals, and their development is influenced by modifiable metabolic, behavioral, and environmental risk factors. Phytochemicals may have cancer-fighting properties and protect against cancer development, slow its spread, and reduce the risk of cancer deaths in humans. This paper aims to review the current literature in regard to the effects of carotenoids in reducing urological cancer risk.     

Residual Stress Induced by Addition of Nanosized TiC in Titanium Matrix Composite

A hot pressing process was employed to produce titanium-based composites. Nanosized TiC particles were incorporated in order to improve mechanical properties of the base material. The amount of nanosized additions in the composites was 0.5, 1.0, and 2.0 wt %, respectively. Moreover, a TiB phase was produced by in situ method during sintering process. The microstructure of the Ti–TiB–TiC composites was characterized by scanning electron microscopy (SEM), electron probe microanalysis (EPMA), electron backscatter diffraction (EBSD), and X-ray diffraction (XRD) techniques. Due to the hot pressing process the morphology of primary TiC particles was changed. Observed changes in the size and shape of the reinforcing phase suggest the transformation of primary carbides into secondary carbides. Moreover, an in situ formation of TiB phase was observed in the material. Additionally, residual stress measurements were performed and revealed a mostly compressive nature with the fine contribution of shear. With an increase in TiC content, linear stress decreased, which was also related with the presence of the TiB phase.     

Determination of Heat Transfer Coefficient for Air-Atomized Water Spray Cooling and Its Application in Modeling of Thermomechanical Controlled Processing of Die Forgings

The paper presents the method and results of determination of heat transfer coefficient for air-atomized water spray cooling with consideration of infrastructural factors of industrial cooling conveyor, such as effect of accelerated air. The established values of heat transfer coefficient were implemented into a numerical model of cooling line, with special definition of sprayers and the movement of the part subjected to quenching. After quantitative validation on selected samples, the obtained coefficients were used for the solution of the technological problem by means of localized cooling rate enhancement, which forms a case study confirming reliability of the established water spray heat transfer functions and suitability of the determined models for design of thermomechanical controlled processing of complex-geometry parts.     

NiO–Ba0.95Ca0.05Ce0.9Y0.1O3−δ as a Modified Anode Material Fabricated by the Tape Casting Method

The development of new chemically resistant anodes for protonic ceramic fuel cells (PCFCs) is urgently required to avoid the costly deep hydrogen purification method. Ba_0.95Ca_0.05Ce_0.9Y_0.1O_3−δ (5CBCY), which is more chemically resistant than BaCaCe_0.9Y_0.1O_3−δ, was here tested as a component of a composite NiO–5CBCY anode material. A preparation slurry comprising 5CBCY_, NiO, graphite, and an organic medium was tape cast, sintered and subjected to thermal treatment in 10 vol.% H₂ in Ar at 700 °C. Differential thermal analysis, thermogravimetry, quadrupole mass spectrometry, X-ray diffraction analysis, scanning electron microscopy, the AC four-probe method and electrochemical impedance spectroscopy were used for the investigation. The electrical conductivity of the Ni–5CBCY in H₂–Ar at 700 °C was 1.1 S/cm. In the same gas atmosphere but with an additional 5 vol.% CO₂, it was slightly lower, at 0.8 S/cm. The Ni–5CBCY cermet exhibited repeatable electrical conductivity values during Ni-to-NiO oxidation cycles and NiO-to-Ni reduction in the 5CBCY matrix, making it sufficient for preliminary testing in PCFCs.