Pure phase synthesis of Cu3PS4 and Cu6PS5Cl for semiconductor applications

We have achieved the first reported pure phase synthesis of two new nanoparticle materials, Cu₃PS₄ and Cu₆PS₅Cl. We have achieved this through learning about the potential reaction pathways that CuCl₂, P₂S₅, and 1-dodecanethiol can take. This study has shown that the key variable to control is the state of the phosphorus source when the CuCl₂ is added. If P₂S₅ is added together with the CuCl₂ to dodecanethiol then the reaction will follow a path to Cu₃PS₄, but if it is dissolved in dodecanethiol prior to the addition to CuCl₂ then the reaction will produce Cu₆PS₅Cl. The formation of these two different phases can occur simultaneously, yet we have found sets of conditions that manipulate the reaction system to form each phase exclusively. These nanoparticles could have broad semiconductor or solid electrolyte applications.

We have achieved the first reported pure phase synthesis of two new nanoparticle materials, Cu₃PS₄ and Cu₆PS₅Cl.

There is a need to explore new thin film photovoltaic absorbers, as many of the current thin film technologies have challenges associated with them. The high efficiency materials such as CuIn_xGa_1−xSe₂ (ref. 1–5) and CdTe,^6–8 require the use of the less-abundant elements indium and tellurium. To rectify this short coming, materials that use earth abundant elements such as Cu₂ZnSnSe₄ (CZTSe)^9,10 and amorphous-Si^11–13 have been explored. This class of materials has been unable to reach the efficiencies of the CuIn_xGa_1−xSe₂ and CdTe cells that are necessary to become an economic alternative to fossil fuel based energy. Specifically in the case for CZTSe, the issue is caused by intrinsic defect formation, leading to band tails in the material.^14–17 This defect is caused by the zinc on copper site (Cu_Zn) and the accompanying copper on zinc (Zn_Cu) site.^18,19 This is due to the similar sizes of the Cu¹⁺ and the Zn²⁺ ions.Because of the uncertainties regarding the limitations and future of previously developed earth abundant materials for solar cells, it is necessary to investigate new materials that avoid the pitfalls that have hampered the previous technologies. It has been proposed to use a Cu₃–V–VI₄ (V = P, As, Sb; VI = S, Se) structured material to address these issues.^20–28 This class of materials uses earth abundant cations to allow for production on a terawatt scale. They also avoid the cation switching that has hampered the efficiencies of CZTSe devices, due to the mismatch between the sizes of V⁵⁺ and Cu¹⁺ cations.Some work examining the phosphorus member of the Cu₃–V–VI₄ material family and its potential use as a solar absorber material has been reported in the literature. The reported calculations have estimated that the band gap of the selenide material is within the ideal range of 1.0–1.5 eV, and they have potential for the power conversion efficiencies to be greater than that of CuInSe₂. Experimental studies have confirmed the band gap of Cu₃PSe₄ to be 1.35 eV.²² On the other hand, Cu₃PS₄ with a higher band gap is a potential candidate for a top cell in a tandem cell. Both of the materials have shown a photoelectric response,^22,23 and could be attractive materials for photovoltaic devices.In the past, crystals of Cu₃PS₄ have been synthesized either using chemical vapor transport and temperatures in excess of 850 °C for long periods of time such as 24 hours^20,29 or heating elemental powders of copper, phosphorus and sulfur in sealed evacuated fused silica tubes at high temperatures for extended time periods.^22,27,30 While these techniques produce crystals of Cu₃PS₄ that could be used for fundamental characterization, they are not suitable for fabrication of thin films of Cu₃PS₄. There is a need to pursue and develop new solution based techniques for the synthesis of Cu₃PS₄, if it is to be competitive with other thin film technologies. Using nanoparticles as a method for forming thin films has been employed for a variety of other materials for PV applications.^1,9,31,32The previous solution-based method, to synthesize Cu₃PS₄ nanoparticles has faced significant obstacles.²³ This method is based on reducing both copper and phosphorus to a neutral state and reacting them together to form Cu₃P nanoparticles. These nanoparticles are then reacted with thiourea in a separate reaction. While this procedure does produce Cu₃PS₄ nanoparticles, they are not pure phase. There is the presence of a phosphorus rich phase that is altering the composition and effecting the photoluminescence. If Cu₃PS₄ nanoparticles are to be used a precursor to a solar absorber, they will need to be free of any contaminants that could adversely affect a final film.For this contribution we have examined copper–phosphorus–sulfide system. This material can occur in two main phases, the Cu₃PS₄ enargite phase and the Cu₇PS₆ argyrodite phase. The argyrodite structure also has a chloride phase compound Cu₆PS₅Cl. The enargite phase is of more interest for photovoltaic applications, as either a top material for a multi-junction device or for use in high band gap electronic devices.Argyrodites, while they may not be useful as solar absorbers, have been explored for use as solid electrolytes.^33–35 Cu₆PS₅Cl has been of particular interest due to its high performance and copper mobility.^36,37 This material has shown better conductivities than other materials in the same family. In a similar case to the enargite materials, synthesis of the argyrodites is done in sealed ampule or vacuum based methods.^34–37     

Improved Real-World Glycemic Control With Continuous Glucose Monitoring System Predictive Alerts

Background:Most standalone real-time continuous glucose monitoring (RT-CGM) systems provide predictive low and high sensor glucose (SG) threshold alerts. The durations and risk of low and high SG excursions following Guardian™ Connect CGM system predictive threshold alerts were evaluated.Methods:Continuous glucose monitoring system data uploaded between January 2, 2017 and May 22, 2018 by 3133 individuals using multiple daily injections (MDIs) or continuous subcutaneous insulin infusion (CSII) therapy were deidentified and retrospectively analyzed. Glucose excursions were defined as SG values that went beyond a preset low or high SG threshold for ≥15 minutes. For a control group, thresholds were based on the median of the low SG threshold limit (70 mg/dL) and the high SG threshold limit (210 mg/dL) preset by all system users. During periods when alerts were not enabled, timestamps were identified when a predictive alert would have been triggered. The time before low horizon was 17.5 minutes and the time before high horizon was 15 minutes, of all users who enabled alerts. Excursions occurring after a low SG or high SG predictive alert were segmented into prevented, ≤20, 20-60, and >60 minutes.Results:Excursions were prevented after 59% and 39% of low and high SG predictive alerts, respectively. The risk of a low or high excursion occurring was 1.9 (P < 0.001, 95% CI, 1.88-1.93) and 3.3 (P < 0.001, 95% CI, 3.20-3.30) times greater, respectively, when alerts were not enabled.Conclusions:The predictive alerts of the RT-CGM system under study can help individuals living with diabetes prevent some real-world low and high SG excursions. This can be especially important for those unable to reach or maintain glycemic control with basic RT-CGM or CSII therapy.     

Genetics of P450 oxidoreductase: sequence variation in 842 individuals of four ethnicities and activities of 15 missense mutations

P450 oxidoreductase (POR) is an electron-donating flavoprotein required for the activity of all microsomal cytochrome P450 enzymes. We sequenced 5,655 bp of the POR gene in a representative population of 842 healthy unrelated individuals in four ethnic groups: 218 African Americans, 260 Caucasian Americans, 179 Chinese Americans, and 185 Mexican Americans. One hundred forty SNPs were detected, of which 43 were found in >/=1% of alleles. Twelve SNPs were in the POR promoter region. Fifteen of 32 exonic variations altered the POR amino acid sequence; 13 of these 15 are previously undescribed missense variations. We found eight indels, only one of which was in the coding region. A previously described variant, A503V, was found on 27.9% of all alleles with some ethnic predilection (19.1% in African Americans, 26.4% in Caucasian Americans, 36.7% Chinese Americans, and 31.0% in Mexican Americans). We built cDNA expression vectors for the 13 previously undescribed missense variants, expressed each protein lacking 27 N-terminal residues in Escherichia coli, and assayed the apparent K(m) and V(max) of each in four assays: reduction of cytochrome c, oxidation of NADPH, 17alpha-hydroxylase activity of P450c17, and 17,20 lyase activity of P450c17. The catalytic activities of several missense mutants differed substantially in these assays, indicating that each POR mutant must be assayed separately with each potential target P450 enzyme. The activity of A503V was reduced to a modest but statistically significant degree in all four assays, suggesting that it may play an important role in interindividual variation in drug response.     

Quality standards for bone conduction implants

Conclusion: Bone conduction implants are useful in patients with conductive and mixed hearing loss for whom conventional surgery or hearing aids are no longer an option. They may also be used in patients affected by single-sided deafness. Objectives: To establish a consensus on the quality standards required for centers willing to create a bone conduction implant program. Method: To ensure a consistently high level of service and to provide patients with the best possible solution the members of the HEARRING network have established a set of quality standards for bone conduction implants. These standards constitute a realistic minimum attainable by all implant clinics and should be employed alongside current best practice guidelines. Results: Fifteen items are thoroughly analyzed. They include team structure, accommodation and clinical facilities, selection criteria, evaluation process, complete preoperative and surgical information, postoperative fitting and assessment, follow-up, device failure, clinical management, transfer of care and patient complaints.     

Ratchet-traction effect: An underdiagnosed mechanism of pacing lead dislodgement

Pacing lead dislodgement contributes substantially, to the list of causes of early pacemaker failure.Reel''s syndrome is a rare cause of pacemaker failure, resulting from the dislodging of pacing electrodes by manipulation of the pulse generator by the patient. We describe here an intriguing case of pacemaker lead dislodgement by a novel and frequently underdiagnosed mechanism that mimicked the fluoroscopic diagnosis of reel''s syndrome.     

Recombinant adenoviral vector expressing HCV NS4 induces protective immune responses in a mouse model of Vaccinia-HCV virus infection: A dose and route conundrum

Hepatitis C virus (HCV) leads to chronic infection in the majority of infected patients presumably due to failure or inefficiency of the immune responses generated. Both antibody and cellular immune responses have been suggested to be important in viral clearance. Non-replicative adenoviral vectors expressing antigens of interest are considered as attractive vaccine vectors for a number of pathogens. In this study, we sought to evaluate cellular and humoral immune responses against HCV NS4 protein using recombinant adenovirus as a vaccine vector expressing NS4 antigen. We have also measured the effect of antigen doses and routes of immunization on the quality and extent of the immune responses, especially their role in viral load reduction, in a recombinant Vaccinia-HCV (Vac-HCV) infection mouse model. Our results show that an optimum dose of adenovirus vector (2 × 10⁷ pfu/mouse) administered intramuscularly (i.m.) induces high T cell proliferation, granzyme B-expressing CD8⁺ T cells, pro-inflammatory cytokines such as IFN-γ, TNF-α, IL-2 and IL-6, and antibody responses that can significantly reduce the Vac-HCV viral load in the ovaries of female C57BL/6 mice. Our results demonstrate that recombinant adenovirus vector can induce both humoral and cellular protective immunity against HCV-NS4 antigen, and that immunity is intricately controlled by route and dose of immunizing vector.