Mass Δm Research Articles

A simple, rapid and entertaining method to measure specific heat of metals using liquid nitrogen and Leidenfrost effect

Taking advantage of the fascination of ‘playing’ with liquid nitrogen, this article proposes a didactical experiment involving the use of this liquid to measure the heat capacity of cylindrical metallic blocks (copper, aluminum, brass, and stainless steel; volume ≈ 20 cm3). It also permits to demonstrate qualitatively and quantitatively the Leidenfrost effect. The experimental setup consists of a low-cost recipient adequate for liquid N2 storage, a multimeter and a weighing scale. The experience starts by a rapid immersion of metallic block in liquid N2 and by measuring simultaneously the block’s temperature and the mass of the evaporated liquid along the cooling process. Knowing the latent heat of the liquid L , the evaporated mass Δm during a temperature variation ΔT , the heat capacity is obtained by Cp=L Δm/ΔT . This method allowed to measure the specific heat in the 100–270 K temperature range in less than 3 min and the results are in quite good agreement with the literature data. On the other hand, the cooling rate, measured by temperature and liquid N2 change, clearly shows two regimes as expected by the Leidenfrost effect and the critical heat flux calculated is in good agreement with previous experiments. Such an experiment can be adapted to various student levels and present a didactical approach to important thermodynamical concepts in parallel with appealing phenomena.

Prospects for the observation of continuous gravitational waves from deformed fast-spinning white dwarfs

ABSTRACT There has been a growing interest within the astrophysics community in highly magnetized and fast-spinning white dwarfs (WDs), commonly referred to as HMWDs. WDs with these characteristics are quite uncommon and possess magnetic fields ≥106 G, along with short rotation periods ranging from seconds to just a few minutes. Based on our previous work, we analyse the emission of Gravitational Waves (GWs) in HMWDs through two mechanisms: matter accretion and magnetic deformation, which arise due to the asymmetry surrounding the star’s rotational axis. Here, we perform a thorough self-consistent analysis, accounting for rotation and employing a realistic equation of state to investigate the stability of stars. Our investigation focuses on the emission of gravitational radiation from six rapidly spinning WDs: five of them are situated within binary systems, while one is an AXP, proposed as a magnetic accreting WD. Furthermore, we apply the matter accretion mechanism alongside the magnetic deformation mechanism to assess the influence of one process on the other. Our discoveries indicate that these WDs could potentially act as GW sources for BBO and DECIGO, depending on specific parameters, such as their mass, the angle (α) between the magnetic and rotational axes, and the accumulated mass (δm) at their magnetic poles, which is influenced by the effect of matter accretion. However, detecting this particular class of stars using the LISA and TianQin space detectors seems unlikely due to the challenging combination of parameters such as a large δm, a large α angle and a small WD mass value.

Elastomer-Based Sealing O-Rings and Their Compatibility with Methanol, Ethanol, and Hydrotreated Vegetable Oil for Fueling Internal Combustion Engines.

Green methanol, ethanol, and diesel-based hydrotreated vegetable oils are some of the renewable liquid fuels that show satisfactory performance in diesel engines. A notable advantage of these fuels is that they are renewable and do not require significant modifications in the existing engines for successful operation. Suitable fuel systems, especially their material compatibility, remain unresolved, and therefore, it is a weak link in their large-scale adaptation. Elastomer-based sealing O-rings lose their mechanical properties after a short exposure time to these fuels, adversely impacting their functionality. This research study evaluated the long-term material compatibility of different elastomer-based sealing materials by immersing the O-rings in these test fuels (hydrotreated vegetable oil, methanol, ethanol, and diesel) for different time intervals (i.e., up to 15 months). The material compatibility was assessed mainly by investigating these changes in various mechanical properties of these O-rings, namely tensile strength (ΔTs), elongation at break (ΔEb), Shore A hardness (ΔH), and mass (ΔM). The degradation of mechanical properties was studied and analyzed during the immersion interval from 0.9 to 15.2 months and compared with O-rings kept in a normal atmosphere. It was noted that individual fuels affect various mechanical properties significantly. In a short interval of 0.9 months (28 days), significant changes in the mechanical properties of the sealing O-rings were observed.

(Digital Presentation) Porous Silicon Formed by Electrochemical, Chemical and Combined Etching

This work is devoted the thermophysical characteristics (TPC) of PS formed by Electrochemical, Metal-assisted chemical and combined etching methods. The TPC of PS/MACE+EC formed by the MACE+EC– method is higher than those of the PS/EC and PS/MACE samples formed by the EC and MACE methods. The energy activity of water splitting on the surface of PS/MACE+EC is higher than the energy activity of the PS/EC and PS/MACE samples. The combined (MACE+EC) method is the best method for obtaining PS, which has the highest energy activity in water splitting processes. The activation energy of water splitting processes Ea(PS/MACE+EC) is higher than the energy activity of the Ea(PS/EC) and Ea(PS/MACE) samples. The presence of Ni particles in the pores of PS<Ni> stabilizes the them TPC. The TPC of PS were studied in comparison with the TPC of crystalline (c-Si) and powdered silicon (powder-Si). It is known that PS has a high catalytic activity of hydrogen evolution during photoelectrochemical splitting of water. For example, the use of a surface enriched Ni layer on the surface of a PS photocathode PS<Ni> made it possible to increase its catalytic activity two times higher than the catalytic activity of the Pt- electrode in the reaction of hydrogen evolution [1]. The TPC of PS samples formed by EC, MACE and combined (MACE+EC)- etching methods are studied in comparison with the TPC of c-Si and powder-Si samples, Table. Method Electrolyte Composition Marked I Et1 HF:H2O2=1:1 EC II Et2 HF:H2O2: Ni(NO3)2 =1:1:1 МАСЕ III Et3 HF:H2O2: Ni(NO3)2 =1:1:1 EC+МАСЕ According of electron microscopy research the highest porosity is observed on the PS/MACE+EC samples, the smallest - on the PS/MACE sample formed by the MACE- method. The Raman spectra testify this, PS/MACE+EC(Et3) samples have a higher intensity of the Raman peak at a high-frequency shift due to electron-phonon scattering, the intensity and frequency of which depend on the concentration of scattering centers and, consequently, on the conditions for the formation of pores [2]. The TPC of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) spectra record changes in the mass Δm of the sample and heat flux ΔQ with an isobaric temperature change ΔT at the points of T-characteristic. An analysis of the calorimetric TPC and the TGA and DSC spectra shows that c-Si and powder have almost the same patterns of change in thermal conductivity, in contrast to the PS-spectra. The PS/EC, PS/MACE samples have the maximum change in heat flux Q(PS/EC)=187.6 mW, Q(PS/MACE)=231.6 mW, in contrast to powder-Si Q(powder-Si)=107.1 mW and c-Si ΔQ(c-Si)=65.02 mW. This dependence, which is responsible for the heat flux ΔQ change in the high T-range is associated with the maximum developed surface PS. Due to the fact that the presence of the Ni in the pores of PS<Ni>/MACE and PS<Ni>/MACE+EC stabilizes the TPC of PS, and thereby prevents significant changes in the TPC of Ni-containing PS<Ni>, in contrast to PS that does not Ni-contain in pores. Also have carried out experiments on the evaporation of water droplets at room temperature from the surface of c-Si and PS/EC, PS/MACE PS/MACE+EC samples. Experiments on the evaporation of water droplets at Troom from the surface of crystalline and PS samples obtained by various etching methods showed that the highest energy activity is observed in PS/MACE+EC samples, Ea(PS/MACE+EC) = 0.2087 eV, which is much higher than Ea(PS/EC) = 0.070 eV, Ea(PS/MACE) = 0.050 eV and Еа(c-Si) = 0.025 eV,The porous surface of the PS/MACE+EC sample has the highest energy activity compared to the PS/EC and PS/MACE samples, which is due to the high porosity of PS/MACE+EC. The PS/MACE and PS/MACE+EC samples showed high energy stability over 1 year in water evaporation experiments. The values of the heat capacities of various EC-, MACE-, EC+MACE - etching methods are established: - Cp(c -Si) = 20.7 KJ/gK, Cp(powder-Si) = 13.11 KJ/gK, Cp(PS/MACE) = 12.79 KJ/gK, Cp(PS/AE) = 5.62 KJ/gK.Combination of electrochemical etching with Ni-stimulated and chemical etching (EC+MACE) makes the possibility Ni-containing nanoporous silicon with high energy activity in water splitting processes: - Еа(PS/MACE+EC) = 0.2087 eV, Еа(PS/MACE) = 0.070 eV , Еа(PS/АЕ) =0.050 eV.The Ni- presence in the pores stabilizes the TPC of PS/MACE and PS/MACE+EC. The stability of Ni-containing samples PS/MACE+EC) and Ea(PS/MACE) is maintained for one year. [1] K.B. Tynyshtykbayev et al. Russian Microelectronics, 2016, Vol. 45, Nos. 8–9, pp. 603–612. https://doi.org/10.1134/S106373971608014X[2] K. Tynyshtykbayev et al. ECS Journal of Solid State Science and Technology, 2021 10 013009 DOI: 10.1149/2162-8777/abdd86

JT gravity and near-extremal thermodynamics for Kerr black holes in AdS4,5 for rotating perturbations

We study the near horizon 2d gravity theory which captures the near extremal thermodynamics of Kerr black holes where a linear combination of excess angular momentum δJ and excess mass δM is held fixed. These correspond to processes where both the mass and the angular momenta of extremal Kerr black holes are perturbed leaving them near extremal. For the Kerr AdS4 we hold delta J-mathcal{L}delta M=0 while for Myers-Perry(MP) type Kerr black hole in AdS5 we hold delta {J}_{varphi 1,2}-{mathcal{L}}_{varphi 1,2}delta M=0 . We show that in near horizon, the 2d Jackiw-Teitelboim theory is able to capture the thermodynamics of the higher dimensional black holes at small near extremal temperatures TH. We show this by generalizing the near horizon limits found in literature by parameters mathcal{L} and {mathcal{L}}_{varphi 1,2} for the two geometries. The resulting JT theory captures the near extremal thermodynamics of such geometries provided we identify the temperature {T}_H^{(2)} of the near horizon AdS2 geometry to be {T}_H^{(2)}={T}_H/left(1-mu mathcal{L}right) for 4d Kerr and {T}_h^2={T}_H/left(-mu left({mathcal{L}}_{varphi 1}+{mathcal{L}}_{varphi 2}right)right) for 5d Kerr μ is their chemical potential, with mu mathcal{L}<1 and mu left({mathcal{L}}_{varphi 1}+{mathcal{L}}_{varphi 2}right)<1 respectively. We also argue that such a theory embeds itself non-trivially in the higher dimensional theorydual to the Kerr geometries.

Abstract P4-10-07: It is possible to achieve the same benefits in online models than in face to face programs in bc patients

Abstract It is possible to achieve the same benefits in online models than in face to face programs in breastcancer patients. Introduction: eHealth programs is an emerging area because of the restricted measures for controllingCOVID19 pandemic, to maintain high quality patients’ care. In this sense, Spanish Cancer Associationof Madrid (AECCmad) had an effective exercise oncology face-to-face program that had to be adaptedinto the online model. The purpose of this study is comparing the results from the face-to-face (F-F)initial program with the new one, to evaluate the efficacy of the online model in breast cancer patients(BCP). Methodology: Since 1st of September of 2018 until 31 of March of 2021, a total of 267 BCP in differentstages were assisted in the exercise-oncology unit of the AECCmad: from 2018 to December 2019, 180BCP participated in F-F programs and from September 2020 to March 2021, 87 BCP participated inonline interventions. In both cases, BCP were initially evaluated to checked fulfilled the inclusioncriteria by a nurse. After that, BCP had a one-to-one interview with the exercise-oncologyprofessionals where anthropometrics, cardiorespiratory fitness (CRF), strength, and functionalcapacity was assessed. Then, BCP were included in a supervised exercise program (F-F or online) witha duration of 12 or 8 weeks, respectively, 2 days per week, performing combined exercise andadapting the intensity to each patient. At the end, the same variables were assessed with a twofoldpurpose: to inform patients of the achieved changes and to give them a personalized final report thatwould help women to continue doing exercise. Data were analyzed using SPSS 20, comparingdifferences between interventions with ANCOVA test for quantitative variables or Chi2 test forqualitative variables. Results: 267 BCP completed the exercise-oncology program of AECCmad. 180 participated in the F-Fprogram with a mean age of 52.3(9.0) (50% survivor, 32% undertreatment and 16% with metastaticdisease) and 87 participated in the online version with a mean age of 45.7(10.1) (30% survivor, 51%undertreatment and 20% with metastatic disease). Participants in online groups were significantlyyounger than in F-F groups (MeanDif (ΔM)= 6.6, CI95%= 9.2 - 3.9, p&amp;lt;0.001).Related to programadherence, F-F program had a significant higher adherence than the online model (ΔM=10.2, CI95%=15.9 - 4.4, p=0.001). Related to physical results, CRF and leg strength were significantly higher in F-Fgroups compared with the online model (ΔM= 3.4; CI95%= 0.04-6.7; p= 0.047; and ΔM= 11.6; CI95%=3.6 -19.4; p= 0.005, respectively). By contrast, no differences in strength of upper limbs (ΔM= 0.39; p=0.79) between groups were observed although F-F intervention achieved higher final values than theonline ones. Regarding to body composition, no significant difference in muscle mass (ΔM= 0.1; p=0.66), fat mass (ΔM= -0.9; p= 0.12), and visceral fat mass (ΔM= -5.8; p= 0.08), were observed betweengroups, although better results were observed in F-F interventions. Conclusions: Although F-F and online exercise-oncology programs both improved physical status,these comparisons showed that programs F-F are more effective improving CRF and legs strength thanonline ones, probably due to F-F programs were longer and used specific material. In addition,adherence to F-F programs was significantly higher than the online version, maybe for the reductionof the social aspect in the last one. However, online intervention had similar impact in bodycomposition than F-F ones and allows for greater access to patients in general, but specially those withlow accessibility, living in longer distance, or having difficulties in moving, among others. In this sense,these comparisons suggest online programs should be an effective alternative to improve physicalaspect in BCP. Citation Format: Mónica Castellanos Montealegre, Lucía Gil-Herrero, Soraya Casla-Barrio. It is possible to achieve the same benefits in online models than in face to face programs in bc patients [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-10-07.

ПОРІВНЯННЯ АМІНІВ ЯК ГАЗОУТВОРЮВАЧІВ ВОГНЕЗАХИСНИХ КОМПОЗИЦІЙ ІНТУМЕСЦЕНТНОГО ТИПУ

Purpose. Study of influence of blowing agents amines structure on the construction processes of thermal insulating char layer of intumescent system ammonium polyphosphate/pentaerythritol/amine and fire protection efficiency of this system at high temperatures. Methodology. A fire retardant mixture of ammonium polyphosphate/pentaerythritol/amine was chosen as a model intumescent system. Dispersion of vinyl acetate copolymer with vinyl ether of versatic acid was used as a polymeric component. A step-by-step study of the characteristics of the char layer of the intumescent composition was applied in the study, consisting in the analysis of the characteristics of the char formed after keeping the intumescent composition samples at a certain temperature between 100 and 800 °C, char residue mass (m, %), structure and density of the formed char layer. The method of infrared spectroscopy was used for identification of products of thermolysis of intumescent systems. Determination of fire protection efficiency of intumescent coatings was carried out in a mini-oven under standard fire conditions. Findings. The influence of the structure of amines blowing agents on the formation of char layer of intumescent system ammonium polyphosphate/pentaerythritol/amine was studied. Physico-chemical parameters of char layer formed during high temperature swelling of intumescent system components with varying amine: urea, melamine, dicyandiamide, guanidine, thiocarbamide, formylthiosemicarbazide, thiosemicarbazide, phenylethylcarbamide have been determined. In the temperature range 200–400 oC for systems with linear amines (urea, thiocarbamide, thiosemicarbazide), there is a rapid formation of insulating layer with intense outgassing (high intumescent coefficients K) and the same rapid its destruction with significant losses of char residue mass (Δm). The presence of melamine, dicyandiamide and guanidine in intumescent system provides constancy of intumescent coefficient at minimal mass loss. Chemical transformations of intumescent systems were studied by the method of infrared spectroscopy when the investigated amines were varied. It was found that linear diamines do not form stable spatially branched phosphamide compounds with phosphates as the basis of a thermostable heat-insulating frame. At the same time in IR spectra of char residue systems with melamine, dicyandiamide and guanidine the absorption bands of P-N-C bonds (1070–1050 cm-1) and P-N (980–950 cm-1) up to 600–700 oC are observed. Fire tests proved that melamine, dicyandiamide and guanidine are blowing agents providing maximum protection of metal against fire and can be used for composition of fire retardants for steel constructions.Originality. It has been proved that amines in intumescent polyphosphate system perform at least two functions: blowing agents by means of thermal destruction to incombustible gases and nucleophilic compound that takes part in char layer formation by aminolysis of electrophilic substrates.Practical value. The optimum amine blowing agents for developing formulations of intumescent coatings with enhanced flame retardant properties have been established.

Adiabatic compressed air energy storage technology

Adiabatic compressed air energy storage technology

Hydrothermal alteration in Eshtehard volcanoes, Iran: Constraints from trace elements redistribution and stable isotope geochemistry

We use the mineralogy, trace element compositions and elemental mass balance of volcanic materials collected from propylitic, potassic and phyllic alteration facies in the Eshtehard area of Iran to document the nature and effects of hydrothermal alteration. Incompatible element abundances in hydrothermally–altered samples show transformations that include: (i) depletion of alkalis and alkaline earth elements (i.e., Ba, Sr), (ii) variable behavior of first series transition elements (depletion in Cr, Co and Ni; enrichment in Zn and Cu), and (iii) depletion of HREE, Hf and Th relative to U and LREE. In detail, potassic (associated with a major addition of Cu) and phyllic zones are characterized by enrichment of SiO2 and MgO whereas propylitization depleted SiO2 and MnO, enriched MgO and Fe2O3, and increased LOI. Whole rock geochemistry along hydrothermal facies revealed consistent negative Ce and Eu anomalies, indicating that reducing conditions persisted during hydrothermal processes. Substantial changes in isovalent elements ratios (i.e., K/Ba, K/Rb, Y/Ho, Sr/Eu, Zr/Hf and Eu/Eu*) along the facies illustrate non–charge and radius control behavior are construed as lanthanide tetrad–effect phenomena. The co–occurrence of zigzag patterns (i.e., M and W–shapes) is evidence for partial or incomplete tetrad effect reaction between REE3+ and F-and Cl-rich fluids in hydrothermal systems. Low T4 tetrad–effect values overall suggest rock–fluid interaction involving rather low temperature hydrothermal solutions. Mass (ΔM) and volume (ΔV) were slightly depleted in the propylitic (−3.80% and −5.66%) potassic (−3.48% and −5.66%), and phyllic (−2.52% and −2.91%) zones with isocon slopes of 1.06, 1.06 and 1.03, respectively. We envisage a secondary phenomenon in open system conditions which accompanied fluid–rock interaction as the plausible cause of slight REE tetrad effect observed in the hydrothermally altered samples. Fluid inclusions studies yield homogenization temperatures of 275–596 °C and salinity ranging from 34 to 39 wt% NaCl equivalent suggesting boiling during mineralization in the Eshtehard area. The calculated δ18O and δD of the fluids range between 5.3 and 7.1 and −75 to −62 per mil, respectively. On this basis, we suggest that the ore-forming fluids had a magmatic source and underwent boiling and/or exchange with hydrous minerals.

Target-Triggered Polymerization of Branched DNA Enables Enzyme-free and Fast Discrimination of Single-Base Changes.

SummarySingle-base changes lead to important biological and biomedical implications; however, the discrimination of single-base changes from normal DNA always remains a grand challenge. Herein we developed a DNA recognition and amplification system based on artificial branched DNA, namely, target-triggered polymerization (TTP), to realize enzyme-free and fast discrimination of single-base changes. Branched DNA as monomers rapidly polymerized into DNA nanospheres only with the trigger of specific DNA. Our TTP system worked reliably over a wide range of conditions. Remarkably, our TTP system was capable of discriminating base-changing DNA from normal DNA, including distinguishing 1–4 nucleotide changes and positions of single base, which was attributed to the significant amplification of small differences in hybridization thermodynamics and kinetics. We further proposed a theoretical method for calculating the hybridization probability of nucleic acids, which performed highly consistent with experimental results.

Shadow of a black hole surrounded by dark matter

We consider a simple spherical model consisting of a Schwarzschild black hole of mass M and a dark matter of mass ΔM around it. The general formula for the radius of black-hole shadow has been derived in this case. It is shown that the change of the shadow is not negligible, once the effective radius of the dark matter halo is of order ∼3MΔM. For this to happen, for example, for the galactic black hole, the dark matter must be concentrated near the black hole. For small deviations from the Schwarzschild limit, the dominant contribution into the size of a shadow is due to the dark matter under the photon sphere, but at larger deviations, the matter outside the photon sphere cannot be ignored.

THEORETICAL FUNDAMENTALS FOR DETERMINING SOIL EROSION POTENTIAL (ENERGY CONCEPT) PART 1

Solving problems of anti-erosion technology and machinery design is associated with finding an integral objective parameter that would meet piratical requirements and develop an acceptable determination method. Therefore, the research objective is to develop an integral criterion to determine soil erosion potential (SEP). As a value to characterize SEP it is prosed to use energy ΔА expended to erode and remove the unit weight of a soil mass Δm under specific conditions of its occurrence. Consequently, the development of theoretical prerequisites for the problem under consideration, as well as the experimental determination of ΔА and Δm, can reveal the main regularities in the physical mechanism of erosion processes. We propose to use the thermodynamic potential method to describe soil erosion processes. It has been shown that the Gibbs thermodynamic potential is the most suitable for this purpose since it is possible to design devices for the experimental measurement of independent variables. SEP is an additive and constant value for a given soil and expresses its properties, i.e. it can be adopted as a single integral criterion for assessing the resistance of soils to erosion.

Fast tracking of acoustic resonance frequencies in collection volumes to measure flow

Previously, we demonstrated accurate determinations of the mass of gas in a large collection vessel of known volume from measurements of the pressure and the resonance frequencies of a few acoustic modes. We achieved accurate mass measurements even when linear temperature gradients persisted after adding or removing gas. The change in mass Δm from before and after flow and the collection time Δt may be used to calibrate mass flowmeters. Because the resonance quality factors Q are very high (up to 30000), measuring the complex-valued frequency response using a lock-in amplifier to determine the resonance frequency is slow. This static measurement of mass requires sufficient time to elapse for transient non-linear gradients to dissipate through convection and diffusion. Here, we demonstrate a method to dynamically track the resonance frequency of a large, gas-filled collection vessel while gas is flowing into or out of the vessel. We use positive feedback to excite sustained oscillations at the desired resonance frequency without a lock-in amplifier or frequency synthesizer. As the speed of sound changes, the sustained oscillations track the changing resonance frequency f with response time ~1/f. Preliminary mass flow measurements using this technique agree with a flow standard within their combined uncertainties.

Completion of the universal I–Love–Q relations in compact stars including the mass

Abstract In a recent paper, we applied a rigorous perturbed matching framework to show the amendment of the mass of rotating stars in Hartle's model. Here, we apply this framework to the tidal problem in binary systems. Our approach fully accounts for the correction to the Love numbers needed to obtain the universal I–Love–Q relations. We compute the corrected mass versus radius configurations of rotating quark stars, revisiting a classical paper on the subject. These corrections allow us to find a universal relation involving the second-order contribution to the mass δM. We thus complete the set of universal relations for the tidal problem in binary systems, involving four perturbation parameters, namely I, Love, Q and δM. These relations can be used to obtain the perturbation parameters directly from observational data.

Polymeric seal degradation in nuclear power plants: Effect of gamma radiation on sealing properties

ABSTRACTAn effort has been made to bridge the gap between academic knowledge of polymeric seal degradation and industrial practices. A series of physical and mechanical properties that can be related to the sealing behavior of three commercial samples of nitrile rubber have been studied for their degradation when exposed to gamma radiation. For all samples the glass transition temperature (Tg) and retention factor (RF) were found to increase with total dose whilst percentage change in mass (ΔM%) was found to decrease. The ultimate uptake of carbon dioxide (CO2) did not appear to change with radiation dose but the kinetics of the absorption process were found to decrease, suggesting the formation of crosslinks. The crosslinks formed appear to be dependent on the original material composition and comparison against degradation of material properties supports the theory behind butadiene, BDN, content being linked to a propensity for crosslink clustering. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44618.

Fabrication of poly (lactic acid)/hydroxyapatite (PLA/HAp) porous nanocomposite for bone regeneration

In this study, a poly (lactic acid)/hydroxyapatite (PLA/HAp) porous nanocomposite was fabricated by melt mixing method. Polyethylene oxide (PEO) was added into the nanocomposite to improve compatibility of HAp in the PLA matrix. A porous structure of the nanocomposite was created by using a salt (NaCl) which leaches in water. The influence of HAp's weight, compatibiliser content of porous agent on morphology and mechanical properties of PLA/HAp nanocomposite was investigated by SEM and tensile testing method. The obtained results indicated that the nanocomposite containing 20 wt% HAp, 5 wt% PEO, and an amount of NaCl in proportion with PLA weight (1 : 1) had good mechanical properties with a promising Young's modulus close to the one of cancellous bone (530 MPa) as well as a high porosity. The invitro tests of nanocomposite in simulated body fluids (SBF) were carried out and then pH of SBF solution, variation of material mass (Δm), morphology and phase structure of the nanocomposite were also estimated. The results showed that pH decreased, and Δm had positive or negative values depending on composition and surface of material formed by HAp crystals and the hydrolysis of PLA during immersion time.

The Relation between the Magnetic Field and Spin Period of a Millisecond Pulsar

Based on the function of the accretion induced magnetic decay, the analytical relationship between the magnetic field B and spin period P of a millisecond pulsar (MSP) is investigated, from which the minimum spin period of about one millisecond can be obtained. With this minimum spin period, the range of the neutron star (NS) radius is constrained in comparison with the measured spin period of MSP. Furthermore, we also study the relation between the spin period and the accretion mass ΔM of the NS, and find that the minimum spin period is achieved with the accretion mass of about ∼0.2M⊙, while the bottom magnetic field of about 108 G is obtained.

Mechanical ventilation with heated humidifiers: measurements of condensed water mass within the breathing circuit according to ventilatory settings

Heated wire humidifiers (HWHs) are widely used to heat and humidify gases during mechanical ventilation. The control strategy implemented on commercial HWHs, based on maintaining constant gas temperature at the chamber outlet, shows weaknesses: humidifying performances depend on environmental temperature and ventilatory settings, and often condensation occurs. Herein, we analyzed in vitro HWH performances focusing on the condensation amount according to ventilatory settings. We used a physical model to define the parameters which mainly influence the HWH performances. In order to investigate the influence of minute volume (MV) and frequency rate (fr) on condensation, the other influencing parameters were kept constant during experiments, and we introduced a novel approach to estimate the condensation. The method, based on measuring the condensed vapor mass (Δm), provided more objective information than the visual-based scale used in previous studies. Thanks to both the control of other influencing factors and the accurate Δm measures, the investigation showed the Δm increase with MV and fr. Substantial condensation after 7 h of ventilation and the influence of MV and fr on Δm (i.e., Δm = 3 g at MV = 1.5 L min−1 and fr = 8 bpm and Δm = 9.4 g at MV = 8 L min−1 and fr = 20 bpm) confirm the weaknesses of `single-point temperature' control strategies.

The nature and the mechanism of ion transfer in tungstates Me2+{WO4} (Ca, Sr, Ba) and Me 2 3+ {WO4}3 (Al, Sc, In) according to the data acquired by the tubandt method

The Tubandt method of electrolysis is used for studying the nature of ionic carriers in ceramics of tungstates Me2+{WO4} (Ca, Sr, Ba) and Me23+{WO4}3 (Al, Sc, In) which are solid electrolytes. These compounds have the salt-like islet structure with isolated tetrahedrons {WO42−} and are crystallized in the allied structural types of scheelite (CaWO4) for Me2+ and Sc tungstate (Sc2{WO4}3) for Me3+. The electrolysis is carried out in 2- or 3-section cells (−)Pt|M2n/n+{WO4}|Me2n/n+{WO4}|Pt(+) in air atmosphere at the temperature of ∼900°C and cell voltage of 4 and 300 V. All experiments without exception demonstrate a decrease in the mass of the cathodic section of cells. This points to the negative charge of ionic mass carriers and their transfer towards the Pt(+) electrode. The cathodic briquette mass loss Δm(−) depends linearly on the charge passed through a cell. In all experiments with MeWO4 tungstates, the anodic disk mass remains constant. The electrolysis of Me2(WO4)3 cells is always accompanied by an increase in the anolyte mass Δm(+); however, in all experiments, Δm(−) > Δm(+). All data on mass variation and the results of studying the composition of nearelectrode electrolyte layers by XRD and SEM methods correspond to the condition \(t_{WO_4^{2 - } } > t_C \) (C is the cation), i.e., {WO42−} anions pertain to the major ionic carriers. The transport number \(t_{WO_4^{2 - } } \) is calculated based on the Faraday law from Δm(−). It is shown that the second ionic carrier with the mobility even higher than that of {WO42−} is the O2− ion. For middle values of transport numbers, their ratio is shown to be \(t_{O^{2 - } } \)(0.5–0.8) > (0.2–0.5)\(t_{WO_4^{2 - } } \). No results that would confirm the involvement of Me2+ and Me3+ ions in conduction are obtained.

The birth and death of star clusters in the Milky Way

Simple though admittedly speculative considerations explain why most of our galaxy’s stellar nurseries are highly fragile but a few survive for a remarkably long time.