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The great toll the COVID-19 pandemic had on healthcare workers highlights the need to improve the working environment in hospitals. This is especially true in procedure rooms such as operating and delivery rooms, which inherently require extended exposure to the virus, allow no social distancing, and generate aerosolized virus through the equipment. Therefore, strategies must be created to address these issues. Such a strategy includes calculating and implementing air exchanges per hour with the use of Heating, Ventilation, and Air Conditioning Systems (HVAC). HVAC allows the exchange of air within the procedure room, reducing the amount of exposure to viruses, and resulting in safer working environments for healthcare workers.8,9 Though HVAC creates a safer working environment, there remains a need to create a more cost-effective, efficient system. However, it is imperative to continue improving this system because there will be more pandemics where such a system will save many lives.

A novel near-infrared (NIR) emitting phosphor, Ca4Si2O7F2:Ce3+,Er3+ was synthesized by conventional solid state reaction method and characterized with X-ray diffraction, photoluminescence emission, photoluminescence excitation spectra and fluorescence decay measurements. In Ca4Si2O7F2:Ce3+,Er3+ phosphors, intense NIR emission at 1540 nm which is assigned to the characteristic 4I13/2 → 4I15/2 transition of Er3+ along with the broadband emission of Ce3+ at 490 nm was observed under 380 nm excitation. The luminescence spectra, both in visible (VIS) and NIR regions, and lifetime curves of Ce3+ have been measured to prove energy transfer (ET) from Ce3+ to Er3+. Efficient energy transfer from Ce3+ to Er3+ in Ca4Si2O7F2 is observed and leads to about 10 times enhancement of the Er3+-1540 nm emission when excited at 380 nm. The critical distance between Ce3+ and Er3+ ET in Ca4Si2O7F2 host was calculated, as 14.81 A. The Inokuti-Hirayama (I-H) model is applied in the analysis of the non-exponential fluorescence decay curves. From I-H curve fitting, it is inferred that the electric dipole-dipole interaction is the main process responsible for the energy transfer as well as for the large enhancement of 1540 nm emission. The results indicate that sensitization of Er3+ is possible via 4f-5d transition of Ce3+ in the Ca4Si2O7F2 host.

Crystalline silicon (c-Si) solar cell is to date the most successfully commercialized solar cell. One of the factors which limit the efficiency of c-Si solar cell is a “spectral mismatch”. The mismatch can be removed by modifying the solar spectrum: converting the near UV and blue region of the spectrum, where solar cell response is poor, to NIR region by using suitable phosphors. In the past, several phosphors based on emission of Yb3+/Nd3+ sensitized by f-d transitions of other divalent, or f-f transitions of trivalent rare earths have been studied. These studies demonstrated the concept. However, an ideal phosphor is still not found. In this work tetravalent rare earth, viz. Ce4+ is studied as the sensitizer. Efficient two-step Ce4+→Nd3+→ Yb3+ energy transfer from CT band of Ce4+ is observed. By virtue of this energy transfer, efficient absorption of near UV light and conversion to NIR is achieved. These results are significant for improving efficiency of c-Si solar cells using spectrum modification.

New results on NIR emission in Ba2SiO4:Eu2+, Nd3+ phosphors are reported. Though excitation for Eu2+ emission is in predominantly near UV (nUV) region, that for the Nd3+ emission around 1067 nm extends into visible region covering violet and blue part of the spectrum. These results are highly significant for applications where NIR emission with nUV/blue excitation is required, e.g. for improving efficiency of c-Si solar cell, for designing NIR sources using efficient blue LEDs, etc. Energy transfer efficiencies for Eu2+→ Nd3+ energy transfer are estimated by measuring reduction of Eu2+ emission lifetime, and are close to 80%. Possible mechanisms for Eu2+→ Nd3+ energy transfer are suggested. These involve down shifting or quantum cutting.

Molybdate luminescence is usually totally quenched at room temperature. However, molybdate anions can sensitize the luminescence of other activators like Sm3+, Eu3+, Tb3+, Dy3+, etc. These ions emit in the visible region. No emission in the Near Infrared (NIR) region that is based on sensitization by MoO4−2 anion has been reported, though NIR emission has applications in several fields. In this work NIR emission is reported in PbMoO4 doped with Nd3+ or Yb3+. The emission follows excitation by near ultraviolet (nUV) light that can be absorbed by MoO4−2 anion and subsequent energy transfer to Nd3+ or Yb3+. Mechanisms of energy transfers based on cooperative energy transfer (CET) and cross relaxation followed by NIR emission are suggested. It is also suggested that PbMoO4:Yb3+/Nd3+ phosphors hold a potential for applications requiring NIR emission that can be excited by nUV light; e.g. in photovoltaics based on c-Si.

In this work, NIR emission is reported in Y2MoO6 doped with Nd3+ or Yb3+. The emission follows excitation by near ultraviolet (nUV) light that can be absorbed by MoO4−2 anion with subsequent energy transfer to Nd3+ or Yb3+. Moreover, efficient energy transfer from Nd3+ to Yb3+ was also observed. By virtue of this transfer, higher NIR emission intensities were observed for Nd3+,Yb3+ double doped phosphors. The energy transfer mechanisms based on cooperative energy transfer (CET) and cross relaxation followed by NIR emission are suggested. It is also suggested that Y2MoO6:Yb3+, Nd3+ phosphors hold a potential for applications requiring NIR emission that can be excited by nUV light; e.g. in photovoltaics based on c-Si.

This past century has seen the most advancement in medicine, leading to an almost thirty year increase in the average life expectancy. This increase in life expectancy has also increased cancer incidence in the global population. Cancer is a multifactorial disease, and thus its origin cannot be directly correlated with just one cause. To the best of our knowledge, this is the first study investigating how global meat consumption has influenced various cancers’ incidence rates across the world. Although the correlation between meat consumption and cancer risk has been investigated, a global temporal study investigating the national mortality rates of gastrointestinal cancers relating to meat production remains unexplored. We researched causes for the trends between meat production and GI cancer mortality in affluent nations of both the Eastern and the Western hemisphere including: the USA, Canada, Japan, France, and Singapore. Data was collected from the Food and Agricultural Organization of the United Nations and the World Health Organization Cancer Mortality Database. Meat consumption data was unavailable between the 1960s-2010, so meat production data was used instead. Interestingly, the pancreatic cancer mortality rate increased in each country except Canada. The spike is due to increased meat consumption, obesity, lack of screening modalities, poor prognosis, and late diagnosis of the disease. Canada’s 1% drop in mortality rate can be attributed to a decreased smoking rate amongst men (62% to 16% from 1965-2017) as well as an overall decline in meat consumption. The mortality rates of gastric and colorectal cancer (CRC) have decreased despite a meat production increase. Decreased H. pylori prevalence (Europe: 48.8% to 39.8%, North America: 42.4% to 26.6%, and Western Asia: 53.6% to 54.3%), better food preservation, and improvement in environmental conditions have lowered gastric cancer incidence. The CRC mortality rate in the USA, Canada, Japan, and France decreased mostly due to colonoscopy screening measures, better treatment, and decreased red meat consumption. In Singapore, increased obesity and a poor, high caloric diet accounts for an increased CRC mortality rate despite decreased meat production. This rate is exacerbated by lower screening rates due to decreased CRC risk awareness. Gastric and CRC mortality rates decreased despite increases in meat production, while pancreatic cancer incidence rates have increased. These trends are further investigated and necessary to understand in order to lower the mortality rates of GI cancers on a global scale.