Ta-Doped Sb2Te Allows Ultrafast Phase-Change Memory with Excellent High-Temperature Operation Characteristics

Phase-change memory (PCM) has considerable promise for new applications based on von Neumann and emerging neuromorphic computing systems. However, a key challenge in harnessing the advantages of PCM devices is achieving high-speed operation of these devices at elevated temperatures, which is critical for the efficient processing and reliable storage of data at full capacity. Herein, we report a novel PCM device based on Ta-doped antimony telluride (Sb₂Te), which exhibits both high-speed characteristics and excellent high-temperature characteristics, with an operation speed of 2 ns, endurance of > 10⁶ cycles, and reversible switching at 140 °C. The high coordination number of Ta and the strong bonds between Ta and Sb/Te atoms contribute to the robustness of the amorphous structure, which improves the thermal stability. Furthermore, the small grains in the three-dimensional limit lead to an increased energy efficiency and a reduced risk of layer segregation, reducing the power consumption and improving the long-term endurance. Our findings for this new Ta-Sb₂Te material system can facilitate the development of PCMs with improved performance and novel applications.

Trace element partitioning between pyrochlore, microlite, fersmite and silicate melts

We present experimentally determined trace element partition coefficients (D) between pyrochlore-group minerals (Ca₂(Nb,Ta)₂O₆(O,F)), Ca fersmite (CaNb₂O₆), and silicate melts. Our data indicate that pyrochlores and fersmite are able to strongly fractionate trace elements during the evolution of SiO₂-undersaturated magmas. Pyrochlore efficiently fractionates Zr and Hf from Nb and Ta, with D_Zr and D_Hf below or equal to unity, and D_Nb and D_Ta significantly above unity. We find that D_Ta pyrochlore-group mineral/silicate melt is always higher than D_Nb, which agrees with the HFSE partitioning of all other Ti-rich minerals such as perovskite, rutile, ilmenite or Fe-Ti spinel. Our experimental partition coefficients also show that, under oxidizing conditions, D_Th is higher than corresponding D_U and this implies that pyrochlore-group minerals may fractionate U and Th in silicate magmas. The rare earth element (REE) partition coefficients are around unity, only the light REE are compatible in pyrochlore-group minerals, which explains the high rare earth element concentrations in naturally occurring magmatic pyrochlores.

Less-studied TCE: are their environmental concentrations increasing due to their use in new technologies?

The possible environmental impact of the recent increase in use of a group of technology-critical elements (Nb, Ta, Ga, In, Ge and Te) is analysed by reviewing published concentration profiles in environmental archives (ice cores, ombrotrophic peat bogs, freshwater sediments and moss surveys) and evaluating temporal trends in surface waters. No increase has so far been recorded. The low potential direct emissions of these elements, resulting from their absolute low production levels, make it unlikely that the increasing use of these elements in modern technology has any noticeable effect on their environmental concentrations on a global scale. This holds particularly true for those of these elements that are probably emitted in relatively high amounts from other human activities (i.e., coal combustion and non-ferrous smelting), such as In, the most studied element of the group.

Falling Leaves Inspired ZnO Nanorods-Nanoslices Hierarchical Structure for Implant Surface Modification with Two Stage Releasing Features

Inspired from falling leaves, ZnO nanorods-nanoslices hierarchical structure (NHS) was constructed to modify the surfaces of two widely used implant materials: titanium (Ti) and tantalum (Ta), respectively. By which means, two-stage release of antibacterial active substances were realized to address the clinical importance of long-term broad-spectrum antibacterial activity. At early stages (within 48 h), the NHS exhibited a rapid releasing to kill the bacteria around the implant immediately. At a second stage (over 2 weeks), the NHS exhibited a slow releasing to realize long-term inhibition. The excellent antibacterial activity of ZnO NHS was confirmed once again by animal test in vivo. According to the subsequent experiments, the ZnO NHS coating exhibited the great advantage of high efficiency, low toxicity, and long-term durability, which could be a feasible manner to prevent the abuse of antibiotics on implant-related surgery.

Effect of diet quality and ambient temperature on the use of torpor by two species of neotropical nectar-feeding bats

Neotropical bats use torpor as a strategy to save energy when they experience a low energy intake and/or low ambient temperature (T_a). Digestive physiology limits the energy intake of several glossophaginid bats, and could play an important role in the onset of torpor in these tropical animals. We measured the effect that diet quality and T_a had on the use of torpor by the nectar-feeding bats Glossophaga soricina and Leptonycteris yerbabuenae Captive bats were fed with 5% (low) or 35% (high) sucrose solutions while exposed to two different T_a (17.7 and 23.2°C; low T_a and high T_a) in four different treatments: (1) high sucrose:high T_a, (2) high sucrose:low T_a, (3) low sucrose:high T_a and (4) low sucrose:low T_a We measured their energy intake, changes in body mass (ΔM_b) and skin temperature (T_skin) as response variables. Energy intake (in 10 h) was limited when both species fed on 5% sucrose, but body mass gain was only affected in G. soricina. Energy intake and T_a had a negative effect on the minimum T_skin of both species, and ΔM_b affected the time that G. soricina used torpor. Both species remained normothermic on the high sucrose:high T_a treatment, but used torpor on the other three treatments. Bats used torpor during their resting and activity periods. Leptonycteris yerbabuenae spent more time in torpor in the low sucrose:high T_a treatment, while G. soricina used this strategy for longer periods of time in the high sucrose:low T_a treatment. We found that diet quality and T_a played an important role in the use of torpor by nectar-feeding bats.

Phenylalanine hydroxylase deficiency in the Slovak population: genotype-phenotype correlations and genotype-based predictions of BH4-responsiveness

We investigated the mutation spectrum of the phenylalanine hydroxylase gene (PAH) in a cohort of patients from 135 Slovak PKU families. Mutational screening of the known coding region, including conventional intron splice sites, was performed using high-resolution melting analysis, with subsequent sequencing analysis of the samples showing deviated melting profiles compared to control samples. The PAH gene was also screened for deletions and duplications using MLPA analysis. Forty-eight different disease causing mutations were identified in our patient group, including 30 missense, 8 splicing, 7 nonsense, 2 large deletions and 1 small deletion with frameshift; giving a detection rate of 97.6%. The most prevalent mutation was the p.R408W, occurring in 47% of all alleles, which concurs with results from neighboring and other Slavic countries. Other frequent mutations were: p.R158Q (5.3%), IVS12+1G>A (5.3%), p.R252W (5.1%), p.R261Q (3.9%) and p.A403V (3.6%). We also identified three novel missense mutations: p.F233I, p.R270I, p.F331S and one novel variant: c.-30A>T in the proximal part of the PAH gene promoter. A spectrum of 84 different genotypes was observed and a genotype based predictions of BH4-responsiveness were assessed. Among all genotypes, 36 were predicted to be BH4-responsive represented by 51 PKU families. In addition, genotype-phenotype correlations were performed.

Weekly intravesical bacillus Calmette-Guerin (BCG) alternating with epirubicin in Ta and T1 urothelial bladder cancer: An approach to decrease BCG toxicity

Context:

Bacillus Calmette-Guerin (BCG) therapy is the standard treatment for nonmuscle-invasive bladder cancer (NMIBC). However, its toxicity is a major concern.

Aim:

If we reduce the number of BCG doses by half and replace the second half with epirubicin, we may have a lower toxicity while maintaining the same efficacy of BCG. To test this hypothesis, we conducted this study as an update of our previous report.

Setting and Design:

The study included 607 patients with Ta and T1 NMIBC between January 1994 and December 2008.

Materials and Methods:

After transurethral resection of bladder tumor (TURBT), the patients received weekly doses of 120 mg BCG alternating with 50 mg epirubicin for six weeks (three weekly doses of each). Maintenance was given. Recurrence, progression rates, and toxicity were assessed. End points were progression, recurrence, and cancer-specific survival.

Results:

A total of 532 patients were eligible for evaluation (mean age: 58 years; median follow-up: 45 months). Of these, 291 (55%) were free, 157 (29.5%) showed recurrence, and 84 (15.8%) showed muscle-invasive progression. Toxicity developed in 221 patients. These were mild in the majority (167), whereas 10 developed hematuria, 30 severe cystitis, and five systemic complications. The rate of permanent therapy discontinuation was 3.8%.

Statistical Analysis Used:

SPSS package version 16 and Kaplan-Meier curves were used to evaluate survival.

Conclusions:

Reducing the frequency of BCG instillations by half and replacing the second half with epirubicin results in a similar efficacy and a lower toxicity compared with historical cases receiving BCG alone. However, further trials are required to support these results.