Pedometer intervention and weight loss in overweight and obese adults with Type 2 diabetes: a meta-analysis.

AIM: Although pedometer intervention is effective in increasing physical activity among adults with Type 2 diabetes, its impact on weight loss remains unclear. This meta-analysis was aimed to assess whether pedometer intervention promotes weight loss. METHODS: Three different databases were searched for randomized controlled trials (RCTs) published in English up to April 2015. Studies were included if they investigated the effects of pedometer intervention on weight loss, as measured by BMI or weight. Effect sizes were aggregated using a random-effects model. Subgroup and meta-regression analyses were used to identify potential moderators. Eleven RCTs with 1258 participants were included. All enrolled participants were overweight or obese. RESULTS: Pedometer intervention led to significantly decreased BMI [weighted mean difference (WMD) -0.15 kg/m(2) , 95% confidence interval (CI) -0.29 to -0.02 kg/m(2) ] and reduced weight (WMD -0.65 kg, 95% CI -1.12 to -0.17 kg). Dietary counselling seemed to be a key predictor of the observed changes. However, none of the following variables had a significant influence: step goal setting, baseline age, BMI, weight, sex distribution, disease duration, intervention duration, and baseline values or change scores for total or moderate-to-vigorous physical activity. After completion of the pedometer intervention, non-significant declines in BMI and weight were observed during the follow-up periods. CONCLUSIONS: Pedometer intervention promotes modest weight loss, but its association with physical activity requires further clarification. Future studies are also required to document dietary and sedentary behaviour changes to facilitate the use of pedometers for weight loss in overweight and obese adults with Type 2 diabetes.

Morphology and mechanical behavior of TTCP-derived calcium phosphate cement subcutaneously implanted in rats.

A pre-hardened, TTCP-derived CPC was immersed in Hanks' solution as well as subcutaneously implanted into abdomen of rats. The implant-soft tissue interfacial morphology was examined and properties of the CPC were evaluated and compared under in vitro and in vivo conditions. The results indicate that the surface of immersed samples appeared rougher and more porous than that of implanted samples and was covered with a layer of fine apatite crystals. The CPC samples implanted for 4 weeks or longer were surrounded by a layer of fibrous tissue, which was further surrounded by a soft tissue capsule comprising numerous fat cells. The soft tissue capsule had a non-uniform distribution in thickness, which increased most significantly between 4 weeks and 12 weeks after implantation. None of polymorphic cells, osteoblast cells or bone cells adjacent to the implant were observed. The majority of original TTCP powder was transformed into apatite after 1 day of either immersion in Hanks' solution or implantation. The average porosity values of samples immersed in Hanks' solution for 4 weeks or longer were significantly larger than those immersed for 1 day or 1 week. The porosity values of samples implanted for different times were not significantly different. The DTS values of Hanks' solution-immersed samples largely decreased after a few weeks of immersion. The implanted samples maintained their strengths throughout the study.

Structure, castability and mechanical properties of commercially pure and alloyed titanium cast in graphite mould.

This report is a study of structure, castability, mechanical properties as well as corrosion behaviour of titanium doped with up to 5 weight percentage (wt%) of a series of alloy elements, including Ta, Mo, Nb, Hf, Zr, Sn, Bi and Ag. The results indicate that, with addition of 1 wt% alloy element, Bi and Mo were most effective in enhancing the castability of titanium. With more alloy elements added, the castability values of most alloys more or less decreased. Except Ti-Mo system, all Ti alloys with a fine acicular morphology had the same crystal structure (hcp) as that of c.p. Ti with a typical lath type morphology. When 3 wt% or more Mo was added, a finer orthorhombic alpha'' phase was formed. The microhardness and bending strength values of Ti alloys were all higher than those of c.p. Ti. Among all alloys, Ti-Mo system exhibited the highest hardness and strength level. For a certain alloy, the bending strength did not necessarily increase with its alloy content. Except Ti-5Zr and Ti-Mo alloys, the bending moduli of most alloy systems were not much different from that of c.p. Ti. All alloys showed an excellent resistance to corrosion in Hanks' solution at 37 degrees C.

Variation in structure and properties of a non-dispersive TTCP/DCPA-derived CPC immersed in Hanks' solution.

The present work is to characterize a non-dispersive, fast-setting and high-strength tetra calcium phosphate (TTCP)/dicalcium phosphate anhydrous (DCPA)-based calcium phosphate cement (nd-CPC) recently developed in the authors' laboratory. Comparison between this CPC and a conventional TTCP/DCPA-based CPC (c-CPC) is made. The results show that, during setting c-CPC reaches its pH plateau after 10 min, while nd-CPC approaches plateau after 20 min. During immersion in Hanks' solution the pH values of both cements reach their maxima after immersion for a few days, then decline eventually to near neutrality. With immersion time TTCP and DCPA phases gradually dissolve and apatite phase precipitates. The nd-CPC has a higher apatite formation rate and denser structure than c-CPC under similar conditions, especially at early stage. The nd-CPC also demonstrates higher strength both during setting and after immersion.

Phase transitions of silver and silver-palladium alloys immersed in mercury.

A series of Ag-Hg and Ag-Pd-Hg phases have been prepared by immersion in mercury and subsequent heat treatment of pure Ag and a series of Ag-Pd alloys. Phase transitions, along with the changes involved in morphology and chemistry, are investigated. Experimental results indicate that when mercury-immersed Ag discs are heat-treated at 90 degrees C for 12 h, large (>50 microm) crystals with Ag/Hg atomic ratios close to those of stoichiometric AgHg(2) form on the Ag surface. Heat treatment for 36 h causes these crystals to disintegrate into smaller (majority <10 microm) Ag(2)Hg(3) (gamma(1)) crystals. After 60 h, the stoichiometric gamma(1) crystals further breakdown into even smaller stoichiometric AgHg(beta(1)) crystals. The oft-referenced beta(1) phase Ag(1.1)Hg(0.9) is not supported in the present study. Addition of Pd to Ag has a dramatic effect on the morphology of the gamma(1) phase. With more addition of Pd, large-faceted and elongated gamma(1) crystals tend to grow in the midst of smaller matrix gamma(1) crystals. All three different Pd-containing crystals have (Ag + Pd)/Hg ratios very close to those of the stoichiometric gamma(1) phase, indicating that added Pd tends to replace Ag, rather than Hg, in the gamma(1) phase.

Augmentation of tendon-bone healing by the use of calcium-phosphate cement.

The healing of a hamstring graft to bone is the weak link in the reconstruction of a cruciate ligament using this donor material. We therefore investigated the augmentation of healing at the tendon-bone interface using calcium-phosphate cement (CPC). We performed semitendinosus autograft reconstructions of the anterior cruciate ligament on both knees of 22 New Zealand white rabbits. The interface between the grafted tendon and the bone tunnel for one knee was filled with CPC. Six rabbits were killed at the end of the first and second post-operative weeks in order to evaluate the biomechanical changes. Two rabbits were then killed sequentially at the end of weeks 1, 3, 6, 12 and 24 after operation and tissue removed for serial histological observation. Histological examination showed that the use of CPC produced early, diffuse and massive bone ingrowth. By contrast, in the non-CPC group of rabbits only a thin layer of new bone was seen. Mechanical pull-out testing at one week showed that the mean maximal tensile strength was 6.505 +/- 1.333 N for the CPC group and 2.048 +/- 0.950 N for the non-CPC group. At two weeks the values were 11.491 +/- 2.865 N and 5.452 +/- 3.955 N, respectively. Our findings indicate that CPC is a potentially promising material in clinical practice as regards its ability to reinforce the fixation of the tendon attachment to bone and to augment the overall effectiveness of tendon healing to bone.

Effect of chromium content on structure and mechanical properties of Ti-7.5Mo-xCr alloys.

The present work is a study of a series of Ti-7.5Mo-xCr alloys with the focus on the effect of chromium content on the structure and mechanical properties of the alloys. Experimental results show that low hardness, strength and modulus binary Ti-7.5Mo alloy is comprised primarily of fine, acicular martensitic alpha' phase. When 1 wt % Cr is added, a small amount of beta phase is retained. With 2 wt % or more chromium added, the entire alloy becomes equi-axed beta phase with bcc crystal structure. The average beta grain size decreases with Cr content. When the alloy contains about 2-4 wt % Cr, a metastable omega phase is present. In Ti-7.5Mo-2Cr alloy appears the highest omega intensity accompanied with high microhardness, bending strength and modulus. The omega-induced embrittling effect is most profound in Ti-7.5Mo-2Cr alloy that exhibits a terrace type fracture surface covered with numerous micron-sized dimples. The alloys with higher Cr contents show normal ductile type fractography with much larger deformation dimples. The present results indicate that Ti-7.5Mo-(4-6)Cr alloys seem to be potential candidates for implant application.

Transmission electron microscopic study of early stage gamma(1) (Ag(2)Hg(3)) and beta(1) (Ag-Hg) phases: technical note.

Incomplete reaction, residual free mercury, and high volatility of mercury are often major causes of the discrepancy in chemical composition of gamma(1) measured by different methods. The high mercury volatility also proves to be a major difficulty in transmission electron microscopy (TEM) study of high mercury materials. Provided in this report is a preparation method for TEM thin foils that can largely eliminate the mercury loss problem. The results show that the lattice constant of early stage gamma(1) crystals is 10.05 Delta with a chemical composition of Ag(41.08)Hg(58.92) (or Ag(2)Hg(2.87)). The chemical composition data shows that little or no mercury is lost during specimen preparation. The lattice parameters, a and c, of beta(1) crystals are 3.01 and 4.88 Delta, respectively with a chemical composition of Ag(1.1)Hg(0.94). It seems that the present specimen preparation method allows for accurate TEM microanalysis of high mercury amalgam phases such as gamma(1) and beta(1), which has been extremely difficult to do in the past.

Structure-property relationship of cast Ti-Nb alloys.

The present work is a study of the microstructure, mechanical properties and corrosion behaviour of a series of binary Ti-Nb alloys with Nb contents up to 35 wt%, with emphasis placed on the structure-property relationship of the alloys. The results indicate that crystal structure and morphology of the Ti-Nb alloys are sensitive to the Nb content. The cast c.p. Ti has a hexagonal alpha phase with a lath type morphology. The alloys containing 15 wt% or less Nb are dominated by a hexagonal alpha' phase with an acicular, martensitic structure. When containing 17.5-25 wt% Nb, the alloys are primarily comprised of an orthorhombic alpha" phase. With 27.5 wt% Nb, metastable beta phase starts to be retained. With Nb contents higher than 30 wt%, the equi-axed beta phase is almost entirely retained. Small amounts of omega phase are detected in alloys containing 27.5 and 30 wt% Nb. Among all present alloys, Ti-10Nb and Ti-27.5Nb exhibit the highest strengths, while the alpha"-dominated (17.5 and 20Nb) and beta-dominated (> 30Nb) alloys have the lowest moduli. All Ti-Nb alloys show excellent corrosion resistance in Hank's solution at 37 degrees C. From the present data, the microhardness, bending strength and modulus of the various phases in Ti-Nb alloys are compared and tentatively summarized as follows: Microhardness: omega > alpha' > alpha" > beta > alpha (c.p. Ti) Bending strength: omega > alpha' > alpha" > beta > alpha (c.p. Ti) Bending modulus: omega > alpha (c.p. Ti) > alpha' > alpha" > beta

Structure and properties of Ti-7.5Mo-xFe alloys.

The present work is a study of a series of Ti-7.5Mo-xFe alloys, with the focus on the effect of iron addition on the structure and mechanical properties of the alloys. Experimental results indicate that alpha" phase-dominated binary Ti-7.5Mo alloy exhibited a fine, acicular martensitic structure. When 1 wt% or more iron was added, the entire alloy became equi-axed beta phase structure with a grain size decreasing with increasing iron content. A thermal omega phase was formed in the alloys containing iron of roughly between 0.5 and 3 wt%. The largest quantity of omega phase and highest microhardness were found in Ti-7.5Mo-1Fe alloy. The binary Ti 7.5Mo alloy had a lower microhardness, bending strength and modulus than all iron-containing alloys. The largest bending strength was found in Ti-7.5Mo-2Fe alloy. The present alloys with iron contents of about 2-5 wt% seem to have a great potential for use as an implant material.

Particle size effect on structure and properties of dispersed Pd-containing dental amalgam.

Focus of the study is to evaluate the effect of dispersant particle size on the structure and various properties of spherical matrix, irregular dispersant admixed type Pd amalgams. The results indicate that amalgams prepared from smaller dispersant particles have a shorter setting time (faster amalgamation reaction), smaller setting expansion, higher eta' content and lower early stage gamma2 content. Smaller dispersant particles also lead to a slightly higher compressive strength, lower creep value, more cathodic corrosion potential and less early stage mercury vapor release. The particle size effect on corrosion current density and chemical composition of gamma1 phase in aged amalgam is less significant.

Structure and properties of Titanium-25 Niobium-x iron alloys.

The present work studies the effect of iron on microstructure, mechanical properties and corrosion behavior of Ti-25Nb based system with emphasis on improving strength/modulus ratio. Experimental data shows that cast Ti-25Nb-3Fe has a beta phase with a entirely of dendrite morphology. The bending strength/modulus ratio is 24.6 higher than Ti-6Al-4V (17.4) by 41.4% and than c.p. Ti (9.3) by 165%. The critical anodic current density of the metal in 37 degrees C Hank's solutions is lower than approximately 100 microA/cm(2). Ti-25Nb-3Fe alloy has a great potential for use as an implant material.

Structure and immersion behavior of plasma-sprayed apatite-matrix coatings.

The microstructure and properties of a series of plasma-sprayed coatings from sinter-granulated powders fabricated from SiO2, CaO, P2O5 and Na2O-containing HA composite powders on Ti-6Al-4V substrate were reported. The immersion behavior of these coatings in a simulated body fluid (SBF) was also investigated. The results showed that sinter-granulated apatite-matrix powders were irregularly shaped and appeared quite similar. XRD patterns showed that during fabrication of the powders, P2O5 and SiO2 enhanced the decomposition of HA structure, while CaO and Na2O did not. Reasonably high bond strengths (45-50 MPa) were obtained from all coatings. The plasma spray process itself enhanced the decomposition of apatite and chemical reactions among different phases. When immersed in SBF, the intensities of such phases as alpha- and beta-TCP in all coatings decreased with immersion time and an apatite precipitation took place on all coating surfaces. The immersed SiO2- and CaO-containing HA (HSC) coating had the highest rate of apatite precipitation among all coatings. The variations in calcium ion concentration in simulated body fluid indicated that the HSC-immersed solution reached its maximal Ca concentration the earliest, while the HSCP (HA, SiO2, CaO and P2O5)-immersed solution reached its maximum the latest.

Surface reaction of stoichiometric and calcium-deficient hydroxyapatite in simulated body fluid.

In the present study, the immersion behavior of two kinds of sintered HA with different Ca/P ratios in two different extracellular simulated solutions (Tris buffer and Hank's solutions) was investigated and compared. Results indicated that an as-received Ca-deficient HA (FHA) had a lower Ca/P ratio, larger linear shrinkage and higher density than a stoichiometric HA (MHA). When FHA powder was calcined at 900 degrees C, its Ca-deficient apatite structure was unstable and a significant amount of beta-TCP phase was formed. When heated to 1250 degrees C in air, the highly crystalline apatite structure of MHA was still stable without any noticeable decomposition. The FTIR spectra indicated that both immersed MHA and FHA in Hank's solution were gradually covered with a layer of precipitated apatite during immersion. When immersed in Tris buffer solution, neither HA showed significant changes in their FTIR spectra. SEM observation indicated that the precipitation rate on immersed FHA surface was much higher than that on MHA surface when immersed in Hank's solution. The weight loss and pH data confirmed the higher dissolution rate of FHA than MHA in Hank's solution.

Morphology and immersion behavior of plasma-sprayed hydroxyapatite/bioactive glass coatings.

A series of hydroxyapatite/bioactive glass (HA/BG) coatings have been plasma-sprayed on Ti6Al-4V substrate using HA/BG powders that were prepared by both sinter-granulation and direct mixing methods. The morphology and immersion behavior of these coatings in a simulated body fluid (SBF) were investigated. The results showed that in-house fabricated BG and sinter-granulated HA powders were irregularly shaped and dense. When 5 wt % or more BG was added in HA, the powder became rough and porous. X-ray diffraction (XRD) patterns showed that the presence of BG enhanced the decomposition of HA structure during fabrication of the powders. Reasonably high bond strengths were obtained from all coatings. The granulated type HA/BG coatings showed no significant differences in bond strength from the mixed type HA/BG coatings. The plasma spray process itself and the presence of BG enhanced the decomposition of apatite. Surface morphology of all sinter-granulated type coatings was similar to that of monolithic HA coating, that was comprised of patches of smooth and shiny glassy film and irregularly-shaped particles on its surface. The dissolution depth of plasma-sprayed coatings immersed in SBF was largely dependent on the type and composition of the coating. Granulated type HA/BG coatings were much less dissolvable than monolithic HA or mixed type HA/BG coatings. It seems that the presently used granulation method for the preparation of HA/BG powders plays a predominant role in determining the dissolution behavior of the plasma-sprayed coatings.

Structure and properties of cast binary Ti-Mo alloys.

Structure and properties of a series of binary Ti-Mo alloys with molybdenum contents ranging from 6 to 20 wt% have been investigated. Experimental results indicated that crystal structure and morphology of the cast alloys were sensitive to their molybdenum contents. The hexagonal alpha' phase c.p. Ti exhibited a feather-like morphology. When Mo content was 6 wt%, a fine, acicular martensitic structure of orthorhombic alpha" phase was observed. When Mo content was 7.5 wt%, the entire alloy was dominated by the martensitic alpha" structure. When Mo content was increased to 10 wt% or higher, the retained beta phase became the only dominant phase. Among all Ti-Mo alloys, the alpha" phase Ti-7.5Mo alloy had the lowest hardness. The bending strength of Ti-7.5Mo was similar to that of Ti-15Mo and Ti-13Nb-13Zr, and higher than c.p. Ti by nearly 60%. The bending modulus of the alpha"-dominated Ti-7.5Mo alloy was lower than that of Ti-15Mo by 22%, of Ti-6A1-4V by 47%, of Ti-13Nb-13Zr by 17%, and of c.p. Ti by 40%.

Effect of particle configuration on structure and properties of dispersed Pd-containing dental amalgam.

The present work investigates the effect of particle configuration on the structure and properties of four dispersed type Pd-containing amalgams with the same chemical composition. The results indicate that particle configuration plays an important role not only in the structure and chemistry, but also in such properties as compressive strength, creep and mercury release rate. Compromises among the various properties of the present Pd amalgams are needed, when a decision on particle configuration is to be made. As mechanical properties or corrosion resistance is concerned, the amalgam should comprise at least one spherical alloy (matrix or dispersant). As far as mercury release is concerned, the amalgam should comprise irregular dispersant alloy. The amalgam fabricated from irregular dispersant and spherical matrix particles seems to serve all well.

Immersion behavior of RF magnetron-assisted sputtered hydroxyapatite/titanium coatings in simulated body fluid.

The focus of the present study was on the dissolution/degradation behavior of a series of magnetron-sputtered, single-layered HA/Ti coatings on Ti-6Al-4V substrate immersed in SBF. Changes in coating morphology, crystal structure, and adhesion strength with immersion time are characterized. XRD, FTIR, and LVSEM results consistently indicate that highly crystalline monolithic HA coating is very dissolvable in SBF. The monolithic HA coating is largely delaminated in 3 weeks and entirely peeled off the substrate in 7 weeks. The dissolution is even greater for 95HA/5Ti coating, which severely disintegrated in only 1 week. The amorphous-like coatings sputtered from targets comprising 10 vol % or more Ti, however, appeared almost intact, and their adhesion strengths, which were all higher than 60 MPa, did not change much (within 10%) even after 14 weeks of immersion. The coatings from targets comprising roughly 10-50 vol % Ti combine advantages of high and nondeclining adhesion strength, high resistance to SBF attack, and possibly much higher bioactivity (with large amounts of Ca, P, etc., dissolved in the coatings) than that of Ti.

Characterization of hydroxyapatite and titanium coatings sputtered on Ti-6Al-4V substrate.

A series of thin (<10 microm), single-layered HA/Ti coatings were deposited on Ti-6Al-4V substrate using a radio frequency magnetron-assisted sputtering system. The adhesion strength, microstructure, and chemistry of the coatings were characterized. Experimental results showed that higher Ti contents in targets or coatings resulted in higher deposition rates. When Ti was added the highly crystalline structure of monolithic HA coating was largely disrupted and the coating became amorphous-like. The highly crystalline structure of the monolithic Ti coating was also disrupted by introducing small amounts of Ca, P, and O into the coating. The HA/Ti coatings had quite uniform thicknesses and appeared smooth, dense, and well bonded to the substrate. A scanning electron microscope with an energy dispersive spectroscopy system showed that monolithic HA, 95HA/5Ti, 25HA/75Ti, and 50HA/50Ti coatings had the lowest Ca/P ratios while the 75HA/25Ti coating had the highest. The adhesion strengths of all coatings were between 60 and 80 MPa.

Structural characterization of pulsed laser-deposited hydroxyapatite film on titanium substrate.

Pure, crystalline hydroxyapatite (HA) films with thicknesses of roughly 10 microns have been deposited on titanium substrate using the pulsed laser deposition (PLD) technique. Experimental results indicate that the structure and properties of the PLD-HA films varied with deposition parameters. The PLD process used in the present study did not induce significant amounts of calcium phosphate phases other than apatite, or significant changes in the behaviour of hydroxyl or phosphate functional groups. Broad face scanning electron microscopy showed that HA coating was comprised of numerous essentially spheroidal-shaped particles of different sizes, while the lateral morphology indicated that columnar and dome-shaped structures both existed in the film. Many pinholes and crevices observed on coating surfaces were linked to the original substrate surface crevices/craters. The adhesion strength of the coating, mostly in the range of 30-40 MPa, was found to be closely related to the fractography of the tested specimen. The fracture surfaces of specimens with higher bond strengths were usually accompanied by a higher degree of deformation and coating-substrate debonding, while the fracture of specimens with lower bond strengths occurred more frequently within HA coatings in a more brittle manner. The energy dispersive spectroscopy-determined Ca/P ratios of raw HA powder (1.78) and sintered HA target for PLD (1.79) were very close, indicating that the sintering process used in the present study essentially did not change the Ca/P ratio of HA. After the PLD process, the Ca/P ratio of the HA film increased to 1.99. Cross-sectional scanning electron microscopy-energy dispersive spectroscopy point analysis indicated that the value of the Ca/P ratio was significantly higher in the region near the surface, particularly near the coating-substrate interface, than in the coating interior.