Process and apparatus for growing a crystal ribbon

A process and apparatus is disclosed for growing a crystal ribbon of a substance of theoretically infinite length from a melt of the substance. A pair of fixedly positioned edge defining members are partially submerged into the melt so as to break the surface of the melt at a predetermined distance from one another. The edge defining members are wettable by the melt and the predetermined distance substantially corresponds to the width of the crystal ribbon to be grown. The crystal ribbon is grown by contacting the surface of the melt with a seed ribbon between the edge defining members whereby a meniscus of the melt is established on the seed ribbon. The meniscus is stabilized by the meniscus of the melt on the edge defining members. Pulling the seed crystal ribbon away from the melt results in continuous growth of the crystal ribbon

Development of improved wraparound contacts for silicon

A developmental process for fabricating 2 X 4 cm back surface field silicon solar cells featuring wraparound contacts and screen printed dielectric isolation is described. The process was then used to fabricate a number of cells for evaluation and study, as well as to establish the validity of the process sequence. While a number of cells exhibiting relatively good conversion efficiencies were produced, nearly all had low I-V curve factors for the level of efficiencies attained. Cells with conversion efficiencies of more than 15 percent (air mass zero and 25 C) had fill factors of only 0.76. Evidence as to the cause of this has not been conclusive, but is most probably linked to isolation failure in the wraparound dielectric and associated shunting problems

Demonstration of the feasibility of automated silicon solar cell fabrication

An analysis of estimated costs indicate that for an annual output of 4,747,000 hexagonal cells (38 mm. on a side) a total factory cost of $0.866 per cell could be achieved. For cells with 14$1.22 per watt of electrical output. A laboratory model of such a facility was operated to produce a series of demonstration runs, producing hexagonal cells, 2 x 2 cm cells and 2 x 4 cm cells

Coplanar back contacts for thin silicon solar cells

A process for fabricating 2 to 3 mil wraparound solar cells was formulated. Sample thin wraparound cells were fabricated using this process. The process used a reinforced perimeter construction to reduce the breakage that occurs during handling of the wafers. A retracting piston post was designed and fabricated to help minimize the breakage that occurs during the screen printing process. Two alternative methods of applying the aluminum back surface field were investigated. In addition to the standard screen printed back surface field, both spin-on and evaporated aluminum techniques were researched. Neither spin-on nor evaporated aluminum made any noticeable improvement over the screen printing technique. A fine screen mesh was chosen for the application of the aluminum paste back surface field. The optimum time and temperature for firing the aluminum turned out to be thirty seconds at 850 C. The development work on the dielectric included looking at three dielectrics for the wraparound application. Transene 1000, Thick Film Systems 1126RCB and an in house formulation 61-2-2A were all tested. Cells with pre-dielectric thickness of 3.0-0-3.5 mils using Transene 1000 as the wraparound dielectric and the procedure outlined above showed an average efficiency of 10.7 percent. Thinner cells were fabricated, but had an unacceptable yield and efficiency

Screen printing technology applied to silicon solar cell fabrication

The process for producing space qualified solar cells in both the conventional and wraparound configuration using screen printing techniques was investigated. Process modifications were chosen that could be easily automated or mechanized. Work was accomplished to optimize the tradeoffs associated with gridline spacing, gridline definition and junction depth. An extensive search for possible front contact metallization was completed. The back surface field structures along with the screen printed back contacts were optimized to produce open circuit voltages of at least an average of 600 millivolts. After all intended modifications on the process sequence were accomplished, the cells were exhaustively tested. Electrical tests at AMO and 28 C were made before and after boiling water immersion, thermal shock, and storage under conditions of high temperature and high humidity

Automated fabrication of back surface field silicon solar cells with screen printed wraparound contacts

The development of a process for fabricating 2 x 4 cm back surface field silicon solar cells having screen printed wraparound contacts is described. This process was specifically designed to be amenable for incorporation into the automated nonvacuum production line. Techniques were developed to permit the use of screen printing for producing improved back surface field structures, wraparound dielectric layers, and wraparound contacts. The optimized process sequence was then used to produce 1852 finished cells. Tests indicated an average conversion efficiency of 11% at AMO and 28 C, with an average degradation of maximum power output of 1.5% after boiling water immersion or thermal shock cycling. Contact adherence was satisfactory after these tests, as well as long term storage at high temperature and high humidity

Wildland inventory and resource modeling for Douglas and Carson City Counties, Nevada, using LANDSAT and digital terrain data

The potential of using LANDSAT satellite imagery to map and inventory pinyon-juniper desert forest types in Douglas and Carson City Counties, Nevada was demonstrated. Specific map and statistical products produced include land cover, mechanical operations capability, big game winter range habitat, fire hazard, and forest harvestability. The Nevada Division of Forestry determined that LANDSAT can produce a reliable and low-cost resource data. Added benefits become apparent when the data are linked to a geographical information system (GIS) containing existing ownership, planning, elevation, slope, and aspect information

A change in the NICE guidelines on antibiotic prophylaxis

Since 2008, NICE clinical guidelines have stated: ‘Antibiotic prophylaxis against infective endocarditis is not recommended for people undergoing dental procedures’. This put UK guidance at odds with guidance in the rest of the world, where antibiotic prophylaxis is recommended for patients at high-risk of infective endocarditis undergoing invasive dental procedures. Many dentists also felt this wording prohibited the use of antibiotic prophylaxis, regardless of the wishes of the patient or their personal risk of infective endocarditis and made it difficult for them to use their clinical judgment to deliver individualised care in the best interests of their patients. NICE have now changed this guidance to ‘Antibiotic prophylaxis against infective endocarditis is not recommended routinely for people undergoing dental procedures.’ This article examines the implications of this small but important change

Public understanding and awareness of and response to monkeypox virus outbreak: A cross-sectional survey of the most affected communities in the United Kingdom during the 2022 public health emergency.

OBJECTIVES: Our objective was to examine the public response to public health and media messaging during the human monkeypox virus (MPXV) outbreak in the UK, focusing on at-risk communities. METHODS: A co-produced, cross-sectional survey was administered in June and July 2022 using community social media channels and the Grindr dating app. Basic descriptive statistics, logistic regression, and odds ratio p values are presented. RESULTS: Of 1932 survey respondents, 1750 identified as men, 88 as women, and 64 as gender non-conforming. Sexual identity was described as gay/lesbian/queer (80%), bisexual (12%), heterosexual (4%), and pansexual (2%); 39% were aged <40 years; 71% self-identified as White, 3% as Black, 8% as Asian, 2%as LatinX, and 11% as 'Mixed or Other' heritage groups. In total, 85% were employed and 79% had completed higher education. A total of 7% of respondents identified themselves as living with HIV. Overall, 34% reported limited understanding of public health information, 52% considered themselves at risk, 61% agreed that people with MPXV should isolate for 21 days, 49% reported they would first attend a sexual health clinic if symptomatic, 86% reported they would accept a vaccine, and 59% believed that MPXV originated from animals. The most trusted sources of information were healthcare professionals (37%), official health agencies (29%), and mainstream media (12%). CONCLUSIONS: Vaccine acceptability was very high, yet the understanding and acceptance of public health information varied. Social determinants of health inequalities already shaping the UK landscape risk were compounded in this new emergency. Engagement with structurally disadvantaged members of affected communities and better dissemination of public health messaging by trusted healthcare professionals are essential for the public health response

Stark Broadening of the B III 2s-2p Lines

We present a quantum-mechanical calculation of Stark line widths from electron-ion collisions for the $2s_{1/2}-2p_{1/2,3/2}$, lambda = 2066 and 2067 A, resonance transitions in B III. The results confirm the previous quantum-mechanical R-matrix calculations but contradict recent measurements and semi-classical and some semi-empirical calculations. The differences between the calculations can be attributed to the dominance of small L partial waves in the electron-atom scattering, while the large Stark widths inferred from the measurements would be substantially reduced if allowance is made for hydrodynamic turbulence from high Reynolds number flows and the associated Doppler broadening.Comment: 21 pages, 4 figures; to be published in Phys. Rev.