An industrially melted glass with complex composition in the Li
2O–Al
2O
3–SiO
2 system was annealed at temperatures in the range from 700 to 1000
°C. At temperatures up to 825
°C, a β-quartz solid ...solution crystallized, while at higher annealing temperatures keatite was formed. Up to an annealing temperature of 850
°C, the samples were transparent. During annealing at 750
°C, the concentration of the formed β-quartz crystals increased up to a value of 80
wt%, however, the number of crystals remained constant (within the limits of error) for annealing times from 4 to 120
h. Within that period of time, a slight increase in the mean crystallite size (from 16 to 22
nm) was observed, while the lattice parameter (
a-axis) decreased. As shown by Rietveld refinement, during annealing, the SiO
2-concentration of the crystals increased continuously, and the β-quartz solid solution was depleted in Li
2O, MgO and Al
2O
3. During crystallization, the viscosity of the glass phase increased which decelerated further crystal growth. Finally, the crystallization was frozen in.
A base glass of composition 3.5 Li2O∙0.15 Na2O∙0.2 K2O∙1.15 MgO∙0.8 BaO∙1.5 ZnO∙20 Al2O3∙67.2 SiO2∙2.6 TiO2∙1.7 ZrO2∙1.2 As2O3 (in wt.%), melted and provided by SCHOTT AG (Mainz), was used to study ...the crystallisation mechanism of lithium alumino-silicate glass employing X-ray diffraction combined with neutron diffraction and non-isothermal differential scanning calorimetry (DSC). A high-quartz solid solution of LiAlSi2O6 with nanoscaled crystals forms at 750°C. Quantitative Rietveld refinement of samples annealed at 750°C for 8h determined a crystallised fraction of around 59wt.%. The room temperature crystallised phase adopts an ordered, β-eucryptite-like structure (2×2×2 cell) with Li ordered in the structural channels. The Avrami parameter (n ∼ 4), calculated from DSC data using different theoretical approaches, indicates that bulk crystallisation occurs and that the number of nuclei increases during annealing. The activation energy of the crystallisation is 531±20kJ mol−1.
► Nanoscaled high-quartz crystals from a multicomponent lithium alumino-silicate glass. ► Combined X-ray and neutron diffraction structural refinement. ► β-Eucryptite-like structure (2×2×2 cell) with Li ordered in the structural channels. ► 3-Dimensional bulk crystallisation mechanism with an increasing number of nuclei. ► Usage and validation of an alternative approach to calculate the Avrami parameter.
The pool size of mobile, i.e. non-structural carbohydrates (NSC) in trees reflects the balance between net photosynthetic carbon uptake (source) and irreversible investments in structures or loss of ...carbon (sink). The seasonal variation of NSC concentration should reflect the sink/source relationship, provided all tissues from root to crown tops are considered. Using the Smithsonian canopy crane in Panama we studied NSC concentrations in a semi-deciduous tropical forest over 22 months. In the 9 most intensively studied species (out of the 17 investigated), we found higher NSC concentrations (starch, glucose, fructose, sucrose) across all species and organs in the dry season than in the wet season (NSC 7.2% vs 5.8% of dry matter in leaves, 8.8/6.0 in branches, 9.7/8.5 in stems, 8.3/6.4 in coarse and 3.9/2.2 in fine roots). Since this increase was due to starch only, we attribute this to drought-constrained growth (photosynthesis less affected by drought than sink activity). Species-specific phenological rhythms (leafing or fruiting) did not overturn these seasonal trends. Most of the stem volume (diameter at breast height around 40 cm) stores NSC. We present the first whole forest estimate of NSC pool size, assuming a 200 t$\text{ha}^{-1}$forest biomass: 8% of this i.e. ca. 16 t$\text{ha}^{-1}$is NSC, with ca. 13 t$\text{ha}^{-1}$in stems and branches, ca. 0.5 and 2.8 t$\text{ha}^{-1}$in leaves and roots. Starch alone (ca. 10.5 t$\text{ha}^{-1}$) accounts for far more C than would be needed to replace the total leaf canopy without additional photosynthesis. NSC never passed through a period of significant depletion. Leaf flushing did not draw heavily upon NSC pools. Overall, the data imply a high carbon supply status of this forest and that growth during the dry season is not carbon limited. Rather, water shortage seems to limit carbon investment (new tissue formation) directly, leaving little leeway for a direct CO₂ fertilization effects.
Background
Adolescent athletes participating in overhead throwing sports suffer a variety of overuse elbow injuries, many of which have been well described in the literature. Nonunion stress ...fractures of the olecranon across the epiphyseal plate, however, have received little attention.
Purpose
To describe this unusual clinical entity in the differential diagnosis of the adolescent athlete with elbow pain and to demonstrate that operative treatment is an effective means of quickly and safely returning the patient to sporting activities.
Study Design
Case series; Level of evidence, 4.
Methods
Five adolescent baseball pitchers (mean age, 15 years) who suffered chronic elbow pain and who were diagnosed with olecranon epiphyseal stress fracture nonunions were treated with open reduction and internal fixation using a 7.0 cancellous screw and washer with or without 18-gauge tension banding.
Results
Return to preoperative range of motion was achieved at a mean of 8.6 weeks (range, 3.4-16.6 weeks). Patients were clinically asymptomatic at a mean of 11 weeks (range, 7.7-13.6 weeks) after surgery. Radiographic evidence of stress fracture union was achieved at a mean of 15.4 weeks (range, 6.1-33 weeks), including 1 patient with a delayed union according to radiographs, which healed at 33 weeks. Patients were started on a light strengthening program at 5 to 7 weeks and a throwing progression program at 15.6 weeks (range, 6.4-28.1 weeks). All 5 patients were able to return to their previous level of activities, with a mean return time of 29.4 weeks (range, 18.9-40.4 weeks).
Conclusion
Surgical management of olecranon apophysis stress fractures provided excellent results with minimal complications in this series of 5 consecutive cases.
Rapid demographic shifts have left Puerto Rico with a large older population, necessitating a greater understanding of behavioral risk factors that would sustain successful aging. Data was analyzed ...from the Puerto Rican Elderly: Health Conditions (PREHCO) study participants (n=3781, >60y) at baseline and 2y follow-up. Behavioral risk factors included smoking, alcohol use, exercise, and number of meals/day; all analyzed independently and in a combined behavioral score (range 0–7; unhealthier-to-healthier). A successful aging score (SAS) was defined by attributing points for outcomes of cognitive and physical function, chronic diseases, social and religious engagement, depression, and self-rated health, for a total score of 0–17 (unhealthier-to-healthier aging). Sub-scores for physical conditions vs. cognitive-psychosocial markers were created. Two-year SAS was regressed on baseline behavioral risk factors, adjusting for sex, age, education, and health insurance. The combined behavioral score was associated with SAS (β (SE): 0.16 (0.04) p<0.0001), as well as with the cognitive-psychosocial sub-score (0.12 (0.03); p=0.0002), but not the physical conditions sub-score (p=0.73). Number of meals/day (adequate vs. extreme) was associated with higher 2y SAS (Mean (SE): 11.07 (0.06) vs. 10.65 (0.16); p=0.039). Those who exercised vs. not (11.38 (0.12) vs. 10.97 (0.06); p<0.001), as well as those who played sports vs. not (11.17 (0.07) vs. 10.94 (0.08); p=0.003) had higher 2y SAS. Alcohol use and smoking were not associated with aging score. Among older Puerto Ricans, healthier behavioral risk factors significantly predict 2y successful aging, as a composite health and wellbeing definition. Cognitive-psychosocial outcomes may benefit more from healthy behaviors during aging.
A time projection chamber (TPC) is a strong candidate for the central tracker of the international linear collider (ILC) experiment and we have been conducting a series of cosmic ray experiments ...under a magnetic field up to 4T, using a small prototype TPC with a replaceable readout device: multi-wire proportional chamber (MWPC) or gas electron multiplier (GEM). We first confirmed that the MWPC readout could not be a fall-back option of the ILC-TPC under a strong axial magnetic field of 4T since its spatial resolution suffered severely from the so called E×B effect in the vicinity of the wire planes. The GEM readout, on the other hand, was found to be virtually free from the E×B effect and gave the resolution determined by the transverse diffusion of the drift electrons (diffusion limited). Furthermore, GEMs allow a wider choice of gas mixtures than MWPCs. Among the gases we tried so far a mixture of Ar–CF4-isobutane seems promising as the operating gas of the ILC-TPC because of its small diffusion constant especially under a strong magnetic field. We report the spatial resolution obtained with the GEM readout in this gas mixture. Also presented is the spatial resolution of a GEM-based ILC-TPC estimated from the measurement with the prototype.
The gelation behavior of pre-renneted skim milk concentrate during and after spray drying is investigated in this work, which forms the basis for an encapsulation process. This process consists of ...renneting at 4 °C prior to drying, an initial gelation during drying and a final gelation under controlled rehydration conditions. The aim of this study was to gain a deeper understanding of the gelation process during spray drying by rheological and film and spray drying experiments. For this purpose, steep temperature gradients were applied to assess gelation time and maximal gel strength under fast up-heating conditions to temperatures typical for spray drying. Additionally, the drying behavior during film drying was varied by different dry matter concentrations of the gelling solutions and air temperatures, resulting in different times for the first drying stage. All results were correlated with the degree of aggregation (DA), the characteristic parameter for the state of gelation. The results of the film drying experiments are comparable to the gelation experiments. The gelation process takes more time than spray drying, but it is faster than film drying. Moreover, the gelation only takes place within the first drying stage and, therefore, the drying of SMCs (skim milk concentrate) with lower TS (total solid) contents results in better gelled capsules after spray drying.
Adolescent athletes participating in overhead throwing sports suffer a variety of overuse elbow injuries, many of which have been well described in the literature. Nonunion stress fractures of the ...olecranon across the epiphyseal plate, however, have received little attention.
To describe this unusual clinical entity in the differential diagnosis of the adolescent athlete with elbow pain and to demonstrate that operative treatment is an effective means of quickly and safely returning the patient to sporting activities.
Case series; Level of evidence, 4.
Five adolescent baseball pitchers (mean age, 15 years) who suffered chronic elbow pain and who were diagnosed with olecranon epiphyseal stress fracture nonunions were treated with open reduction and internal fixation using a 7.0 cancellous screw and washer with or without 18-gauge tension banding.
Return to preoperative range of motion was achieved at a mean of 8.6 weeks (range, 3.4-16.6 weeks). Patients were clinically asymptomatic at a mean of 11 weeks (range, 7.7-13.6 weeks) after surgery. Radiographic evidence of stress fracture union was achieved at a mean of 15.4 weeks (range, 6.1-33 weeks), including 1 patient with a delayed union according to radiographs, which healed at 33 weeks. Patients were started on a light strengthening program at 5 to 7 weeks and a throwing progression program at 15.6 weeks (range, 6.4-28.1 weeks). All 5 patients were able to return to their previous level of activities, with a mean return time of 29.4 weeks (range, 18.9-40.4 weeks).
Surgical management of olecranon apophysis stress fractures provided excellent results with minimal complications in this series of 5 consecutive cases.
PDF
