With these two selected etching gases, there is a chemical component (from the SiCl4) and a sputter component (mainly Ar). The resulting etching characteristic then depends on the gas mixture and selected powers. Chemical etching of GaAs in the direction is usually two to five times faster than in the perpendicular [0 1 1] direction, therefore increasing the effect of the separated holes. The hole occupation is given with respect to the click here aspect ratio in Figure 5. For both etching

times, the number of QDs per hole increases with increasing aspect ratio. https://www.selleckchem.com/products/sn-38.html Compared to the results in Figure 2, this is a bit surprising because the number of QDs per hole decreases with decreasing aspect ratio although the hole diameter is strongly

increasing. Apparently, the tendency of higher occupation numbers for larger holes is influenced by the aspect ratio of the holes. Therefore, it is possible to decrease the occupation by using larger holes with smaller aspect ratios. Figure 5 Influence of the aspect ratio on the hole occupation. The influence of the occupation and diameter of the holes depending on the aspect ratio is given for 10 (a) and 15 s (b) of etching time. With this basic approach of two separated exposure spots, the diameter of the holes increases with decreasing aspect ratio. The advantage of a hole with smaller aspect ratio therefore comes with a disadvantage of a larger hole. Nevertheless, a smaller MAPK inhibitor number of QDs per hole nucleate with decreasing aspect ratio but larger hole size. This can be seen for both etching times shown. Increasing the etching time leads to larger holes as 3-mercaptopyruvate sulfurtransferase seen before, but smaller aspect ratio and thus smaller occupation. At last, the influence of the etching depth is investigated. The etch rate depends strongly on the size of the etched structure, see Figure 3. At first, it increases very strongly with the hole area, which is due to

the supply shortage of the etching gases through the small hole size. With increasing size of the etched structure, this effect becomes negligible and the etch rate converges to the etch rate of a free surface. The largest structures show about an eight times higher etching rate than the smallest investigated structures, which has to be taken into account if structures with different sizes are etched at the same time. The influence of depth on the occupation is investigated next. The 20 s etched holes were too deep for SEM investigation, and therefore, AFM images were used for all samples in Figure 6. The distribution of occupation numbers is shown for three different etching times for an initially equal hole size inside the resist. Figure 6 Influence of depth on the amount of nucleating QDs per holes. In (a), the fraction of the number of QDs per hole nucleating inside a hole is given. With increasing etching duration and therefore depth, the number of QDs per hole decreases.

In this study, labour status was based on self-reported current economic status with five mutually exclusive categories: full-time employment (>32 h/week), part-time employment (<32 h/week), unemployment, disability pension, and homemaker. The ethnic background of the respondent was based on the country of origin of the mother. In case the mother was born in The

Netherlands, the country of birth of the father was leading (CBS 2003). Different ethnic groups were defined, based on differences in experiences of migration (refugees or labour migrants) and differences in geographical and cultural distance from the Netherlands. Three ethnic minority groups were defined: (1) Turks and Moroccans, (2) Antilleans and Surinamese, and selleck chemicals llc (3) refugees. Turks and Moroccans initially came as labour Eltanexor datasheet migrants to the Netherlands from the early 1960s, while the migration of Surinamese and Antilleans/Arubans is related to the colonial past. Refugees are another important group of migrants from designated countries such as Afghanistan, Algeria, Angola, Bosnia, China, Chile, Croatia, Democratic Republic of the Congo, Eritrea, Hong Kong, Iran, Iraq, Kosovo, Liberia, Nigeria, Sudan, Serve, Sierra Leone, Somalia, South Korea, Syria and former Yugoslavia. Immigrants from other countries were not included in the analysis (n = 296). Subjects were divided into three

groups according to their highest level of educational attainment. A high educational level CHIR-99021 molecular weight was defined as higher vocational training or university; an intermediate educational level was defined as higher secondary schooling or intermediate vocational training, and a low educational level was defined as no education, primary school,

lower and intermediate secondary schooling or lower vocational training. Marital status was used to distinguish those subjects married or living together with Smad inhibitor others. Health measures Self-reported health (SRH) was measured by asking subjects to rate their overall health on a 5-point scale, ranging from ‘excellent’, ‘very good’, ‘good’ and ‘fair’ to ‘poor’. Those reporting less than ‘good health’ were defined as having a poor health (Fayers and Sprangers 2002). Health was also measured with the Dutch version of the Short Form 36 Health Survey (SF-36) (Ware and Sherbourne 1992). The SF-36 consists of 36 items that were used to calculate scores on eight dimensions: physical functioning, general health, mental health, bodily pain, social functioning, vitality, role limitation due to emotional health problems, and role limitation due to physical health problems. Scores could range from 0 to 100, with a higher score indicating a better health related quality of life. Statistical analysis Characteristics of subjects were analysed using descriptive statistics.

GLPG0259 free base is poorly soluble in aqueous media, and its solubility decreases with increasing pH (<0.01 mg/mL at pH 7). Two approaches were developed in parallel to overcome this low solubility and to improve compound bioavailability after dosing in a solid dosage form. The first approach was a salt screening, this website which resulted in the selection of the fumarate salt for further formulation development work. The water solubility of

the GLPG0259 fumarate salt, as compared with that of the free base, was increased to 1.9–2.7 mg/mL. The impact of the improvement in solubility was confirmed in a comparative bioavailability study in fasted dogs. In that study, GLPG0259 fumarate salt (suspension in 20% [w/v] hydroxypropyl-ß–cyclodextrin, pH 3, or as Crenigacestat order crystalline powder in capsule form) resulted in plasma exposure similar to that of GLPG0259 free base in suspension in 20% acidified hydroxypropyl-ß–cyclodextrin, but 4-fold higher plasma exposure than that of GLPG0259 free-base crystalline powder in capsule form (data not shown). In humans, administration of GLPG0259 fumarate salt as a crystalline powder in capsule form leads to 50% lower bioavailability than that of GLPG0259 free base

given as a solution in 40% (w/v) hydroxypropyl-ß–cyclodextrin, pH 3 (study 3). The lower performance of the fumarate capsule in humans than in dogs is explained by the higher percentage of hydroxypropyl-ß–cyclodextrin (40% versus 20%) in the liquid formulation, which enhances GLPG0259 free-base solubility. Epigenetics inhibitor Concomitant food intake with the solid

dosage form Beta adrenergic receptor kinase prevents this decrease in bioavailability by increasing the solubility further. The second approach was the improvement of GLPG0259 solubility by physical modifications of the drug substance – in particular, the development of solid dispersion formulations with GLPG0259 free base in an amorphous form homogenously dispersed in a polymer matrix. The free-base solid dispersion as a powder or pellets filled into capsules was tested in fasted dogs, and both solid dispersion formulations showed GLPG0259 plasma exposure similar to that of the fumarate salt as a crystalline powder in capsule form. Similar results were obtained in humans (study 4). In the Biopharmaceutical Classification System, drugs are classified according to measurements of solubility and permeability.[20] Regarding GLPG0259, it is a poorly soluble compound, with solubility that decreases with increased pH. The absorption of GLPG0259 was not measured in vivo in humans (there are no data after intravenous dosing), but its permeability assessed using the well established in vitro system, based on the human adenocarcinoma cell line Caco-2, was good, with an apparent permeability coefficient (Papp) of 12.4 10-6 cm/s and limited efflux (Papp B2A/Papp A2B = 2).

However, our ACY-1215 cost experimental results contradict the anticipation. The phenomenon can be ascribed to the compensation by the increase of their diameter. Based on our experimental results, the growth time plays an important role in density and morphology control of ZnO NWs and thus modifies the optoelectronic

properties for versatile devices. Conclusions In summary, the vertical arrays of well-aligned c-axis orientation ZnO NWs have been synthesized on silicon substrate by VS growth mechanism at a relatively low growth temperature. By varying the growth time, we can adjust the areal density, length, and diameter of ZnO NWs and modify the structural and optoelectronic properties accordingly. PL spectra measured at room temperature exhibit a sharp UV peak and broad green Selleckchem AZD1390 band, Selleckchem VE-822 corresponding to the NBE and defect-related emissions, respectively. When the growth time increased, the average diameter of NWs became larger and thus the surface-to-volume ratio became lower. Therefore, higher surface states of ZnO NWs with smaller diameters can be

responsible for the origin of enhanced green emission. ZnO NWs with strong alignment and uniform distribution can also minimize the reflectance to 5.7% in the visible region. In addition, field emission features revealed that the growth time plays an important role in density- and morphology-controlled ZnO NWs. It is reasonable to expect that the ZnO NWs can be modified to meet the requirements for versatile optoelectronic devices. Acknowledgements This work was supported by the Green Technology Research Center of Chang Gung University and the National Science Council (NSC) of www.selleck.co.jp/products/Gefitinib.html Taiwan under contract numbers NSC100-2815-C-155-013-E, NSC100-2112-M-182-004,

and NSC101-2112-M-182-003-MY3. References 1. Jiang CY, Sun XW, Lo GQ, Kwong DL, Wang JX: Improved dye-sensitized solar cells with a ZnO-nanoflower photoanode. Appl Phys Lett 2007, 90:263501.CrossRef 2. Xu L, Shen H, Li X, Zhu R: Enhanced ultraviolet emission from ZnO thin film covered by TiO2 nanoparticles. Chin Opt Lett 2009, 7:953–955.CrossRef 3. Huang MH, Mao S, Feick H, Yan H, Wu Y, Kind H, Weber E, Russo R, Yang P: Room-temperature ultraviolet nanowire nanolasers. Science 1897, 2001:292. 4. Manoharan MP, Desai AV, Neely G, Haque MA: Synthesis and elastic characterization of zinc oxide nanowires. J Nanomater 2008, 2008:849745.CrossRef 5. Ng HT, Han J, Yamada T, Nguyen P, Chen YP, Meyyappan M: Single crystal nanowire vertical surround-gate field-effect transistor. Nano Lett 2004, 4:1247.CrossRef 6. Heo YW, Tien LC, Kwon Y, Norton DP, Pearton SJ, Kang BS, Ren F: Depletion-mode ZnO nanowire field-effect transistor. Appl Phys Lett 2004, 85:2274.CrossRef 7. Lee CH, Yoo J, Doh YJ, Yi GC: ZnO/Mg 0.2 Zn 0.8 O coaxial nanorod heterostructures for high-performance electronic nanodevice applications. Appl Phys Lett 2009, 94:043504.CrossRef 8. Li QH, Liang YX, Wan Q, Wang TH: Oxygen sensing characteristics of individual ZnO nanowire transistors.

J Gerontol A Biol Sci Med Sci 57:M473–M478PubMed 8. Leipzig RM, Cumming RG, Tinetti ME (1999)

Drugs and falls in older people: a systematic review and meta-analysis: I. Psychotropic drugs. J Am Geriatr Soc 47:30–39 9. Nevitt MC, Cummings SR, Kidd S, Black D (1989) Risk factors for recurrent nonsyncopal falls. A prospective study. JAMA 261:2663–2668 10. Tinetti ME, Speechley M, Ginter SF (1988) Risk factors for falls among elderly persons living in the community. N Engl J Med 319:1701–1707PubMed 11. Studenski S, Duncan PW, Chandler J, Samsa G, Prescott B, Hogue C, Bearon LB (1994) Predicting falls: the role of mobility and nonphysical factors. J Am Geriatr Soc 42:297–302PubMed 12. Rubenstein LZ, Josephson KR (2002) The epidemiology of falls and syncope. Clin Geriatr Med 18:141–158CrossRefPubMed 13. Dunn JE, Rudberg MA, Furner SE, Cassel CK (1992) Mortality, disability, and falls in older persons: the role of underlying disease and disability. Thiazovivin nmr Am J Public Health 82:395–400CrossRefPubMed 14. Schwartz AV, Nevitt MC, Brown BW Jr, BAY 80-6946 order Kelsey JL (2005) Increased falling as a risk factor for fracture among older women: the study of osteoporotic fractures. Am J Epidemiol

161:180–185CrossRefPubMed 15. Lamb SE, Jorstad-Stein EC, Hauer K, Becker C (2005) Development of a common outcome data set for fall injury prevention trials: the Prevention of Falls Network Europe consensus. J Am Geriatr Soc 53:1618–1622CrossRefPubMed 16. Bailey IL, Lovie JE (1976) Anlotinib manufacturer New design principles for visual acuity letter charts. Am J Optom Physiol Opt 53:740–745PubMed 17. Ginsburg AP (1984) A new contrast sensitivity vision test chart. Am J Optom Physiol Opt 61:403–407PubMed 18. Gibson JJ (1950) The perception of visual surfaces. Am J Psychol 63:367–384CrossRefPubMed

GNAT2 19. Folstein MF, Robins LN, Helzer JE (1983) The Mini-Mental State Examination. Arch Gen Psychiatry 40:812PubMed 20. Pincus T, Summey JA, Soraci SA Jr, Wallston KA, Hummon NP (1983) Assessment of patient satisfaction in activities of daily living using a modified Stanford Health Assessment Questionnaire. Arthritis Rheum 26:1346–1353CrossRefPubMed 21. May D, Nayak US, Isaacs B (1985) The life-space diary: a measure of mobility in old people at home. Int Rehabil Med 7:182–186PubMed 22. Paffenbarger RS Jr, Hyde RT, Wing AL, Hsieh CC (1986) Physical activity, all-cause mortality, and longevity of college alumni. N Engl J Med 314:605–613PubMed 23. Liang KY, Zeger SL (1986) Longitudinal data analysis using generalized linear models. Biometrika 73:13–22CrossRef 24. Gelman A (2008) Scaling regression inputs by dividing by two standard deviations. Stat Med 27:2865–2873CrossRefPubMed 25. Coleman AL, Stone K, Ewing SK, Nevitt M, Cummings S, Cauley JA, Ensrud KE, Harris EL, Hochberg MC, Mangione CM (2004) Higher risk of multiple falls among elderly women who lose visual acuity. Ophthalmology 111:857–862CrossRefPubMed 26.

The path of phase transformation has something to do with sample preparation and loading condition. This study results in understanding both the phase transformation path and distributions in germanium, proving that the crystalline

orientation also influences the path of phase transformation in nanoindentation of germanium. Figure 11 presents the process of phase transition in nanoindentation on the (010) plane. The bct5-Ge initially appearing under the indenter transforms into Ge-II with continuing loading, which indicates that the bct5-Ge could be an intermediate in the formation of Ge-II phase similar to silicon, as mentioned in previous researches [16, 25]. However, the bct5-Ge in the surrounding area does not transform into Ge-II Epigenetics inhibitor with continuing loading. check details In addition, the bct5-Ge forming

in nanoindentation on the (101) and (111) planes does not transform into Ge-II structure either. These phenomena suggest that pressure with specific directions could induce phase transition from bct5-Ge to Ge-II structure. In other words, axial force with specific directions could trigger phase transformation from diamond cubic germanium to Ge-II phase besides the hydrostatic stress. Figure 11 The process of phase transformation in nanoindentation on the (010) germanium surface. The indentation depth is (a) approximately 1.2 nm, (b) approximately 2 nm, and (c) approximately 4.5 nm. The bct5-Ge structure always forms around the center of the transformed region and almost still exists after unloading. At the same time, the majority of the mixed structure with fourfold and fivefold coordinated atoms forming under Sclareol pressure stress recovers the diamond structure after load relief. The calculated stress in this region is about 6 GPa, which is much lower than the threshold stress initiating the phase transformation. Hence, it is suggested that the mixed structure mentioned previously is the Nutlin-3 purchase distorted diamond cubic structure. The elastic deformation of this region arises on loading, and it returns back to the original diamond structure during unloading.

The change in the coordination number of the atoms may comes from the inappropriate cutoff radius for calculation of the nearest neighbors. The borders of the transformed regions are mostly parallel to germanium’s slip direction of < 110 >, which influences the shape of deformed layers after nanoindentation. The maximum extending depth of the deformed layers also differs based on the crystal orientation of the germanium contact surface. The distribution of deformed layers on the (111) germanium surface is more compact and has the thinnest depth from the contact surface into the substrate, while those on the (010) and (101) surfaces have great difference in depth on various regions and extend deeper into the substrate. The recovery of the central location in nanoindentation on unloading is recorded in Table 1.

J Am Chem Soc 2011, 133:18506–18509.CrossRef 11. Katz M, Graham G, Duan Y, Liu H, Adamo C, Schlom D, Pan X: Self-regeneration of Pd–LaFeO 3 catalysts: new insight from atomic-resolution electron microscopy. J Am Chem Soc 2011, 133:18090–18093.CrossRef 12. Kizaki H, Kusakabe K, Nogami S, Katayama-Yoshida H: Generation of nano-catalyst particles by spinodal nano-decomposition in perovskite. Appl Phys Express 2008, 1:104001.CrossRef 13. Tian ZX, Inagaki K, Morikawa Y: Density functional theory on the comparison of the Pd segregation behavior at LaO- and FeO 2 -terminated surfaces

of LaFe 1- x Pd x O 3- y . Current Appl Phys 2012, 12:S105.CrossRef 14. buy Blasticidin S Morikawa Y, Ishii H, Seki K: Theoretical study of n -alkane adsorption on metal surfaces. Phys Rev B 2004, 69:041403.CrossRef 15. Sawada H, Morikawa Y, Terakura K, Hamada N: Jahn-Teller distortion and magnetic structures Epoxomicin order in LaMnO 3 . Phys Rev B 1997, 56:12154–12160.CrossRef

16. Giannozzi P, Baroni S, Bonini N, Calandra M, Car R, MK-2206 solubility dmso Cavazzoni C, Ceresoli D, Chiarotti GL, Cococcioni M, Dabo I, Corso AD, Gironcoli S, de Fabris S, Fratesi G, Gebauer R, Gerstmann U, Gougoussis C, Kokalj A, Lazzeri M, Martin-Samos L, Marzari N, Mauri F, Mazzarello R, Paolini S, Pasquarello A, Paulatto L, Sbraccia C, Scandolo S, Sclauzero G, Seitsonen AP, Smogunov A, Umari P, Wentzcovitch RM: QUANTUM ESPRESSO: a modular and open-source software project for quantum simulations of materials. J Phys Condens Matter 2009, 21:395502.CrossRef 17. Vanderbilt D: Soft self-consistent pseudopotentials in a generalized Carnitine dehydrogenase eigenvalue formalism. Phys Rev B 1990, 41:7892–7895.CrossRef

18. Perdew JP, Burke K, Ernzerhof M: Generalized gradient approximation made simple. Phys Rev Lett 1996, 77:3865.CrossRef 19. Barbier A, Stierle A, Kasper N, Guittet M–J, Jupille J: Surface termination of hematite at environmental oxygen pressures: Experimental surface phase diagram. Phys Rev B 2007, 75:233406.CrossRef 20. Shivakumara C: Low temperature synthesis and characterization of rare earth orthoferrites LnFeO 3 (Ln=La, Pr and Nd) from molten NaOH flux. Solid State Commun 2006, 139:165.CrossRef 21. Lee CW, Behera RK, Wachsman ED, Phillpot SR, Sinnott SB: Stoichiometry of LaFeO3 (010) surface determined from first-principles and thermodynamic calculations. Phys Rev B 2011, 83:115418.CrossRef 22. Giraudon J–M, Elhachimi A, Wyrwalski F, Siffert S, Aboukais A, Lamonier J–F, Leclercq G: Studies of the activation process over Pd perovskite-type oxides used for catalytic oxidation of toluene. Appl Catal B: Environmental 2007, 75:157.CrossRef 23. Miquel P, Yamin Y, Lombaert K, Dujardin C, Granger P: Thermal ageing induced effects on Pd/LaFeO3 for NOx reduction by hydrocarbons: influence of the preparation method. Top Catal 2009, 52:1791.CrossRef 24. Humphrey W, Dalke A, Schulten K: VMD: visual molecular dynamics. J Mol Graphics 1996, 14:33.CrossRef 25. Monkhorst HJ, Pack JD: Special points for Brillouin-zone integrations. Phys Rev B 1976, 13:5188.

Antibody drugs with superior efficacy have been developed intensively in the last few decades.

However, since they are produced by mammalian cells such as Chinese hamster ovary, their cost is very expensive and needs to be reduced. For this issue, intensive researches have been continued for production of antibody drugs using microorganisms such as E. coli[17]. Although protein A chromatography is useful to recover antibody drugs from preparations, further chromatography is necessary to obtain the required purity for their clinical use. It is likely that production of antibody drugs by E. coli leads to a further requirement of selective removal of LPS. Considering the selectivity for LPS of the porous supports bearing lipid membranes, their application for purification of antibody drugs is interesting. Chemical stability of porous supports bearing lipid membranes The elution property of separation medium find more CBL0137 manufacturer is a key issue in liquid purification for the pharmaceutical industry. Elution from porous supports bearing lipid membranes of N-octadecylchitosan was evaluated by measuring the total organic buy SIS3 carbon content in an eluent from a column

packed with 20 mL of supports. The total organic carbon in the recovered water described in the experimental section was 400 μg L-1[10]. Even assuming that all of the organic carbons are due to eluted N-octadecylchitosan, the eluted N-octadecylchitosan

(C, 65.7%) is Bcl-2 inhibitor calculated as 3.0 × 10-5 g. This amount is 0.038% of the N-octadecylchitosan immobilized on the 20-mL supports. This stability for alkali is attributable to the stability of the amide linkage used for the immobilization of N-octadecylchitosan as well as the stability of the support material. Any substantial change was not observed in the IR spectra of the porous supports bearing lipid membranes after immersion in 0.5 M NaOH or 0.1 M HCl overnight at ambient temperature. This chemical stability, especially to 0.5 M NaOH immersion which is used as a standard depyrogenation procedure, is robust enough for a practical application in the pharmaceutical industry. Conclusions Porous supports bearing cationic lipid membranes of N-octadecylchitosan assembled in nanoscale adsorb LPS selectively from HSA solution at pH 4.3 to 8.0 with the ionic strength of 0.05 to 0.1. LPS was removed to as low as a detection limit of 0.020 ng mL-1 by a column-wise adsorption with a quantitative recovery of HSA. Since LPS includes a terminal diglucosamine which is negatively charged and highly substituted with long-chain fatty acids, LPS is adsorbed by both an ionic interaction and a hydrophobic one. In addition, the low pKa of the chitosan-based material as well as the rigid gel phase of lipid membranes leads to a relatively weak interaction between HSA and results in the selective adsorption of LPS.

The use of electrospinning to fabricate the silk-based CH5183284 order nanofibers and HAp nanoparticles (NPs) had been exploited to create 2D scaffolds. For instance, efforts to modify silk fibroin nanofibers to attribute properties of HAp was done by soaking in stimulated body fluid (SBF) by Kim et al., and this similar mineralization approach had been also frequently used by other researchers [18,

19]. However, this soaking method by SBF results in superficial attachment of HAp NPs on nanofibers. In order to have HAp NPs with strong bonding with nanofibers, the use of freeze-dried silk crystals and strong chemicals had been adapted to create nanofibers containing HAp NPs [20, 21]. However, it is noteworthy to mention that the use of strong chemicals in that case further restricts the biocompatibility aspect of nanofibers. Therefore, an alternative strategy BMS-907351 chemical structure is needed to fabricate the silk fibroin nanofibers having

the features of HAp NPs. The use of aqueous silk/HAp blend solutions P-gp inhibitor can be considered as an ideal way to form nanofibers. By doing that, HAp NPs will be strongly fixed to nanofibers, and intact nature of silk/HAp can be preserved without using toxic chemicals. However, due to large functional groups present in silk, HAp NPs can lead to form a bond due to abundant hydroxyl groups present in these biologically important materials and make it difficult to electrospun [22, 23]. In this work, for the first time, we presented the use of aqueous regenerated silk fibroin solution blended with HAp NPs using a three-way stopcock connector. In our system, the aqueous silk solution and HAp NPs colloidal suspension combine together at the center of the three-way connector for a short time without giving enough time to precipitate, and this blend solution is immediately ejected out to form nanofibers. Different weight ratios of 10%, 30%, and 50% of HAp NPs were used as blend

solution to electrospun nanofibers. The obtained nanofibers were characterized for various psychochemical characterizations, and interaction of these Fenbendazole nanofibers with fibroblasts was done to study the cell toxicity and cell attachment of nanofibers incorporated with HAp NPs. Methods Materials Silkworm cocoons were obtained from the Rural Development Administration (Suwon, Republic of Korea). Poly(ethylene oxide) (PEO) with an average molecular weight of 200,000 (Sigma-Aldrich, St. Louis, USA) was used as sacrificial polymer to electrospun silk solution and to make HAp/PEO colloid solutions. HAp rod-shaped NPs measuring 30 to 60 nm were obtained from Dae Jung, Siheung, Gyeonggi, Korea. NIH 3 T3 fibroblasts were purchased from ATCC (Manassas, VA, USA.).

The values of κ for the corresponding GM6001 film thicknesses 100, 300, and 400 nm at 300 K increased gradually to approximately 0.52, approximately 1.85, and approximately 3.51 W/m · K, respectively. We also found that the thermal conductivities of the films were 1.7 to 11.5 times lower than that of bulk Fe3O4 (approximately 6 W/m · K) [17]. It has been well understood that the significant reduction in the thermal conductivity of the thin films (100 to 400 nm in thickness) compared to the bulk materials could be due to the enhanced phonon-boundary scattering in thin films predicted previously by Callaway [18]. In addition, we added the theoretical calculation results of Callaway’s model in the same figure

(solid line in Figure 5a,b).

The results predicted by the Callaway model agree reasonably well with the experimental data, including the results for bulk Fe3O4. We can thus confirm that the significant reduction in the thermal conductivity for nanoscale thin films is principally a result of phonon-boundary EPZ015938 scattering. In the following section, the calculation model is discussed in detail. Figure 5 Temperature-dependent conductivities of three Fe 3 O 4 films and a simple theoretical calculation based on the Callaway model. (a, b) Measured thermal conductivities of 100-, 300-, and 400-nm-thick Fe3O4 thin films at temperatures of 20 to 300 K using the 3-ω method, including the thermal conductivity of bulk materials. The solid line denotes thermal conductivity of bulk materials from the

theoretical Callaway model, which includes the this website effect of the impurity, Umklapp process, boundary scattering with film grain size, and film thickness. To determine the temperature dependence of the thermal conductivity, κ(T), in Fe3O4 thin films quantitatively, we performed a theoretical calculation (i.e., fitting) based on the relaxation time model using the following expression predicted by Callaway in 1959 [18]: Immune system (2) where ω is the phonon frequency, k B is the Boltzman constant, ℏ is the reduced Planck constant, x denotes the dimensionless parameter, x = ℏω/k B T, θ D is the Debye temperature, T is the absolute temperature, and c is the velocity of sound. The total combined phonon scattering rate (relaxation time, τ c) is given by (3) where d 1 is the grain size of the thin films (approximately 13.2, approximately 86, approximately 230 nm for the 100-, 300-, and 400-nm-thick films, respectively, from the AFM measurements shown in Figure 1), A and B are independent parameters of temperature and fitting, respectively, and c is the sound velocity, which is highly dependent on the direction of movement of phonons (average c = 2,500 m/s) [17]. To add the film thickness in Equation 3, we modified the phonon scattering rate given as (4) where d 2 is the corresponding film thickness. For the Fe3O4 films, we estimated that the values of A and B in Equation 4 were numerically optimized as approximately 8.