Three-dimensional irradiance and temperature distributions resulting from transdermal application of laser light to human knee-A numerical approach.

The use of light for therapeutic applications requires light-absorption by cellular chromophores at the target tissues and the subsequent photobiomodulation (PBM) of cellular biochemical processes. For transdermal deep tissue light therapy (tDTLT) to be clinically effective, a sufficiently large number of photons must reach and be absorbed at the targeted deep tissue sites. Thus, delivering safe and effective tDTLT requires understanding the physics of light propagation in tissue. This study simulates laser light propagation in an anatomically accurate human knee model to assess the light transmittance and light absorption-driven thermal changes for eight commonly used laser therapy wavelengths (600-1200 nm) at multiple skin-applied irradiances (W cm-2 ) with continuous wave (CW) exposures. It shows that of the simulated parameters, 2.38 W cm-2 (30 W, 20 mm beam radius) of 1064 nm light generated the least tissue heating -4°C at skin surface, after 30 s of CW irradiation, and the highest overall transmission-approximately 3%, to the innermost muscle tissue.

Thermodynamic basis for comparative photobiomodulation dosing with multiple wavelengths to direct odontoblast differentiation.

Multiple wavelength devices are now available for photobiomodulation (PBM) treatments, but their dosimetry for individual or combinatorial use remains unclear. The present work investigated the effects of 447, 532, 658, 810, 980 and 1064 nm wavelengths on odontoblast differentiation at 10 mW/cm2 using either equal treatment time for conventional fluence (300 seconds for 3 J/cm2 ) or varying times to adjust for individual wavelength photon fluence (4.6 p.J/cm2 ). Both 447 and 810 nm significantly increased alkaline phosphatase (ALP) activity, while 1064 nm showed reduced ALP activity at 3 J/cm2 . However, ALP induction was significantly improved when equivalent photon fluence dosing was used. Other wavelengths did not show significant changes compared to untreated controls. The data suggest that accounting for wavelength-specific photon energy transfer during PBM dosing could improve clinical safety and efficacy.

Characterization and effectiveness of a violet LED light for in-office whitening.

OBJECTIVES: This study characterized a violet LED light (V-LED; bright max whitening) tooth whitening device and evaluated its efficacy on stained enamel compared to hydrogen peroxide (HP). MATERIALS AND METHODS: Characterization of the V-LED beam profile was performed using a laser beam-profiler. The irradiance was measured throughout an exposure cycle at 0- and 8-mm distances using an integrating sphere and a spectral radiometer. Bovine enamel/dentin blocks stained with black tea (BT), cigarette smoke (CS), or without staining (CONT) were subjected to V-LED or 40% HP (n = 10/group). Color parameters (ΔL, Δa, Δb, and ΔE00) were measured using a digital spectrophotometer. Light transmission was estimated through 1-mm-thick bovine enamel slices (n = 5). ΔL, Δb, ΔE00, and irradiance were analyzed by two-way ANOVAs and Tukey's tests, Δa by Kruskal-Wallis and Mann-Whitney tests, and light transmission by t-test (α = 5%). RESULTS: Heterogeneous beam distribution was observed for the emitting V-LED chips. After 20 sequential exposures, irradiance levels were reduced 25-50%, regardless of the distance from V-LED. Localized irradiance values were statistically different between beam locations and different distances from the target. V-LED produced lower ΔE00, ΔL, Δa, and Δb values than HP for CONT and BT, with no differences for CS. Light transmittance decreased approximately 98% through 1-mm thick enamel. CONCLUSIONS: V-LED irradiance was heterogeneous and decreased throughout the exposure cycles and was also greatly reduced with increasing tip distance. V-LED produced a significantly lower whitening effect on BT and control teeth. CLINICAL RELEVANCE: This study contributes to the knowledge of V-LED and its clinical use.

Evaluation of a novel deep tissue transvaginal near-infrared laser and applicator in an ovine model.

Photobiomodulation therapy (PBMT) is an effective means of treating muscle spasm and pain. A novel near-infrared laser system has been commercialized for the treatment of myofascial pelvic pain in women (SoLá Therapy, UroShape, LLC). This study was undertaken to determine if this device is capable of delivering therapeutic levels of irradiance to the pelvic muscles and to identify the surface irradiance required to achieve this goal. This novel class IV near-infrared laser and transvaginal applicator were used to deliver near-infrared light energy through the vaginal mucosa of an adult Suffolk/Dorset Ewe. Irradiance was measured on the surface of the levator ani muscle, inside the levator ani muscle, and inside the bladder. Measurements were taken at powers of 5 W and 0.5 W. 3.0% of vaginal surface irradiance was measured inside of the levator ani muscle. 4.4% of vaginal surface irradiance was measured inside the bladder. At 5 W, the novel laser system provided a surface irradiance of 738 mW/cm2. At 0.5 W, the system provided a surface irradiance of 74 mW/cm2. A novel class IV near-infrared laser and transvaginal applicator delivered therapeutic irradiance to the levator ani muscle and bladder of an anesthetized ewe at a power setting of 5 W. A power setting of 0.5 W failed to deliver therapeutic energy into either the levator ani muscle or bladder. Clinical applications targeting deeper tissues such as the pelvic muscles and or bladder should consider power settings that exceed 0.5 W and or irradiance of ≥ 75 mW/cm2.

Can exchange transfusion be replaced by double-LED phototherapy?

Phototherapy is a conventional treatment for neonatal jaundice and widely considered as a safe procedure. Recent developments in light-emitting diode (LED) phototherapy devices have made more effective treatments possible. Exchange transfusion (ET) is typically applied for cases of refractory severe hyperbilirubinemia despite its risk of various complications. Since the therapeutic effect of phototherapy is correlated with its irradiance, ET may be avoided by performing phototherapy with higher irradiation. Recently, we adopted double-LED phototherapy as a bridging treatment to ET to treat a case of severe hyperbilirubinemia. In this case, the continual increase of bilirubin levels was suppressed immediately after its administration, and ET was not required. Throughout the treatment, no complications or increase in oxidative stress was observed. In addition, neurodevelopment was appropriate for the patient's age at the 1-year follow-up, and no findings of kernicterus, including physical and magnetic resonance imaging findings, were observed. We hypothesized that double-LED phototherapy may be a good treatment strategy to replace ET for infants with severe hyperbilirubinemia; however, further investigations regarding safety issues including acute and long-term complications are needed before clinical adaptation.

Photobiomodulation in diabetic wound healing: A review of red and near-infrared wavelength applications.

The development of a painless, non-invasive, and faster way to diabetic wound healing is at the forefront of research. The complexity associated with diabetic wounds makes it a cause for concern amongst diabetic patients and the world at large. Irradiation of cells generates a photobiomodulatory response on cells and tissues, directly causing alteration of cellular processes and inducing diabetic wound repair. Photobiomodulation therapy (PBMT) using red and near-infrared (NIR) wavelengths is being considered as a promising technique for speeding up the rate of diabetic wound healing, eradication of pain and reduction of inflammation through the alteration of diverse cellular and molecular processes. This review presents the extent to which the potential of red and NIR wavelengths have been harnessed in PBMT for diabetic wound healing. Important research challenges and gaps are identified and discussed, and future directions mapped out. This review thus provides useful insights and strategies into improvement of PBMT, including its acceptance within the global medical research community.

ET-B receptors involvement in peripheral opioid analgesia induced by light-emitting diode photobiomodulation in male and female mice.

Currently, photobiomodulation therapy (PBMT) is gaining space in the scientific and clinical environment. To help elucidate the importance of irradiance, this study evaluated the effect of two different PBMT irradiances (3.5 and 90 mW/cm2), given a fixed wavelength of 630 nm and a dose of 2 J/cm2, on mechanical hyperalgesia following Complete Freund's Adjuvant (CFA) intraplantar (i.pl.) injection in mice. Additionally, we investigated the role of peripheral opioid and endothelin-B receptors (ETB-R), as well as sex differences in treatment outcome. Different groups of male or female mice were evaluated 6 and 96 h after CFA. Mechanical hyperalgesia was evaluated 30 min after treatments. Naloxone or Bq-788 administration, fifteen minutes before PBMT or Sarafotoxin S6c, helped determine the involvement of peripheral opioid and ETB-Rs on PBMT. Lastly, ETB-Rs skin immunocontent in both sexes was quantified after PBMT consecutive daily treatments. PBMT at an irradiance of 90 mW/cm2, was more effective than 3.5 mW/cm2. Bq-788 and naloxone administration prevented the effects of PBMT and SRTX S6c; however, PBMT did not influence peripheral ETB-Rs immunocontent. The results suggest that irradiance influences PMBT effect; and that activation of ETB-R play a role in peripheral PBMT opioid induced analgesia. Lastly, PMBT effects do not appear to be sex-dependent.

Improving Effectiveness of Phototherapy in an Academic Center: A Quality Improvement Project.

Neonatal hyperbilirubinemia is a common cause of delayed discharge and readmissions in our institution. As previously published, the irradiance our phototherapy (PT) units provided was below the irradiance recommended by the AAP for intensive phototherapy (>30 µW/cm2/nm). We measured irradiance delivered by our PT units (Drager 4000) using a standardized footprint grid. By varying number of blue and white fluorescent PT lights, height of PT unit above the neonate and type of bed used (open bassinet versus isolette), we determined the optimal PT arrangement needed to deliver intensive PT (30 µW/cm2/nm). We then developed a standardized, multidisciplinary protocol specifying light arrangement and distance required needed to achieve the desired irradiance level. We were able to show improved irradiance following above changes. Onsite measurement of irradiance provided by local phototherapy units and development of a multidisciplinary, standardized protocol are necessary to assure delivery of recommended levels PT for neonates with hyperbilirubinemia.

An evaluation of phototherapy device performance in a tertiary health facility.

INTRODUCTION: A range of phototherapy devices are commercially available. The American Academy of Pediatrics (2004) recommends routine intensity measurement of phototherapy devices to ensure that babies affected by hyperbilirubinemia receive effective phototherapy. OBJECTIVE: The aims of this study were to calculate the irradiance decay velocity of phototherapy devices used in a tertiary care hospital to evaluate whether current maintenance procedures for phototherapy devices are effective, and to contribute to the improvement of a standardized maintenance procedure in daily practice, thus helping to ensure that all babies affected by hyperbilirubinemia receive prompt treatment. METHODS: This research represents a prospective observational study conducted at Dr. Soetomo Academic Teaching Hospital in Surabaya, Indonesia from February 2019-July 2019. The intensities of 11 phototherapy devices were measured at specific times using a Bili Blanket Meter II. We calculated the Δ irradiance differences in µW/cm2/nm and calculated them as velocity µW/cm2/nm/hour of use. RESULTS: Among the 11 phototherapy devices included in this study, nine were fluorescent and two were light-emitting diode (LED) machines. The mean (standard deviation) irradiance decay velocity of the fluorescent lamps was 0.02 (±0.03) µW/cm2/nm/hour of use, while that of the LED lamps was 0.015 (±0.007) µW/cm2/nm/hour of use. The fastest irradiance decay velocity was 0.08 µW/cm2/nm/hour of use, while the slowest irradiance decay velocity was <0.01 µW/cm2/nm/hour of use, both of which were from fluorescent-based devices. There was one fluorescent-based device that provided an intensity lower than the therapeutic level. CONCLUSION: Irradiance decay occurred in all phototherapy device lamps. It is important to perform routinely intensity measurements, regardless of manufacturer recommendations, to avoid ineffective phototherapy resulting from intensities lower than the required therapeutic levels.

The effects of UVB irradiance on vitiligo phototherapy and UVB-induced photocarcinogenesis.

Phototherapy is the most commonly used modality for repigmenting vitiligo. Currently, UVB emitting devices, including narrow-band UVB (NBUVB) and excimer laser/light, are considered as the treatment of choice. While emitting wavelengths at close proximity, excimer lights emit higher irradiance (HI; W/m2 ) compared to NBUVB. Clinical reports have shown that excimer light is more efficacious in treating vitiligo compared to NBUVB, and we demonstrated that irradiance plays a critical role in promoting melanoblasts differentiation. UVB radiation from the sun is closely associated with photocarcinogenesis of the skin. Sunscreens were used to protect the skin by reducing UVB irradiance (low irradiance (LI) UVB). Sunscreen use was associated with skin cancer reduction in clinical trials. Paradoxically, sunscreen use was associated with increased sunburn episodes in the real-world settings. It was shown that UVB-induced sunburn depends on fluence (J/m2 ) but not irradiance of UVB radiation. We investigated the significance of irradiance in the context of UVB-induced carcinogenesis of the skin. For mice receiving equivalent fluence of UVB exposure, the LIUVB-treated mice showed earlier tumor development, larger tumor burden, and more epidermal keratinocytes harboring mutant p53 as compared to their HIUVB-treated counterparts. These results suggested that at equivalent fluence, LIUVB radiation has more photocarcinogenic potential on the skin compared to its HI counterpart. Since development of sunburn with or without sunscreen use indicates that certain threshold of UVB fluence has been received by the skin at LI and HI, respectively, sunburn episodes with sunscreen use (LIUVB) are more damaging to the skin compared to that without sunscreen (HIUVB) application. In summary, since irradiance plays an important role determining the biological effects of UVB radiation on the skin, future related studies should take this critical parameter into consideration.

Standardization of phototherapy for neonatal hyperbilirubinemia using multiple-wavelength irradiance integration.

BACKGROUND: Phototherapy with radiation of 460-490 nm wavelengths provides the most potent therapeutic effect for neonatal jaundice. However, the efficacy of phototherapy has been estimated using single-wavelength detectors with sensitivity at approximately 460 nm. Cyclobilirubin formation capacity (CFC), which comprises the sum of the irradiance values from three wavelengths multiplied by their specific coefficients, has been proposed as an alternative marker to evaluate the efficacy of phototherapy. This study aimed to test whether two types of phototherapy devices with distinct spectral characteristics provide similar therapeutic effects on adjustment of device-to-patient distances to deliver similar CFCs. METHODS: Using a three-wavelength spectroradiometer, CFCs and footprints of the light-emitting diode and fluorescent tube devices were assessed. Having determined the device-specific distances that ensured similar CFCs, 32 newborn infants, requiring phototherapy for hyperbilirubinemia, were randomized into the light-emitting diode and fluorescent tube groups. The total serum bilirubin levels before and after phototherapy were assessed. RESULTS: The light-emitting diode and fluorescent tube devices had comparable CFCs at distances of 60 and 50 cm, respectively. Phototherapy reduced the total serum bilirubin levels from 18.1 to 14.6 mg/dL and from 19.1 to 15.1 mg/dL in the light-emitting diode and fluorescent tube groups, respectively. The two groups did not differ significantly with respect to the patients' clinical backgrounds, serum bilirubin levels, or changes before and after phototherapy. CONCLUSION: At similar CFCs, the two phototherapy devices reduced the total serum bilirubin levels by comparable amounts. Hence, determining CFCs may help predict phototherapy efficacy. This may ensure better safety and greater efficacy of the treatment for newborn infants.

Evaluation of Rh-Hemolytic Disease in Neonates and Management with Early Intensive Phototherapy in the Neonatal Intensive Care Unit.

BACKGROUND OF THE STUDY: In neonates with Rh-hemolytic disease, light emitting diode (LED) phototherapy allows delivery of high spectral irradiance (SI). A linear correlation exists between SI and efficacy of phototherapy with no saturation point. There is scant data on evaluation and early phototherapy using LED units in Rh-hemolytic disease. OBJECTIVE: This study aimed to describe the hemoglobin (Hb), hematocrit (Hct), total serum bilirubin (TSB), phototherapy parameters and short-term outcomes in neonates with Rh-hemolytic disease. METHODOLOGY: Maternal parameters for Rh-isoimmunization were recorded and monitoring of fetal anemia by Doppler ultrasound was done. Early intensive phototherapy within 1 h of birth was initiated for cord blood Hb below 13.6 g/dl and/or TSB greater than 2.8 mg/dl. RESULTS: Fifty Rh positive neonates were enrolled of which 11/50 (22%) received intrauterine transfusions. The maximum TSB remained below 18 mg/dl in 42/50 (84%) of neonates. The mean SI on the trunk was 56.260 ± 8.768 µW/cm2/nm and duration of phototherapy was 7 ± 3.29 days (mean ± SD). There was a positive correlation between strength of indirect antiglobulin test and cord blood Hb: correlation coefficient (r) = 0.295; direct antiglobulin test and duration of phototherapy: r = 0.331. Early packed red blood cell (PRBC) transfusion was required in 8/50 (16%) neonates while 20/50 (40%) required late transfusions. CONCLUSION: With a mean SI of 56.260 ± 8.768 µW/cm2/nm on the trunk, TSB remained below 18 mg/dl in majority thereby avoiding exchange transfusion. Early or late PRBC transfusion requirement was 1 (1-2) (median ± interquartile range).

Nutrient over-enrichment and light limitation of seagrass communities in the Indian River Lagoon, an urbanized subtropical estuary.

Historically, extensive seagrass meadows were common throughout the Indian River Lagoon (IRL) in east-central Florida, USA. Between 2011 and 2017, widespread catastrophic seagrass losses (~95%) occurred in the IRL following unprecedented harmful algal blooms (HABs), including persistent brown tides (Aureoumbra lagunensis). Little is known about how dissolved nutrients and chlorophyll a are related to light limitation or how biochemical factors, such as the elemental composition (C:N:P) and stable isotope signatures (δ13C, δ15N), of seagrasses within the IRL relate to coverage. Accordingly, we conducted a survey from 2013 to 2015 at 20 sites to better understand these relationships. Results showed a negative correlation between DIN and salinity, indicating freshwater inputs as a DIN source. Seawater N:P ratios and chlorophyll a concentrations were higher in the urbanized, poorly-flushed northern IRL segments. Kd values were higher in the wet season and often exceeded seagrass light requirements (0.8 m-1) for restoration, demonstrating light limitation. Species distribution varied by location. Halodule wrightii was ubiquitous, whereas Syringodium filiforme was not found in the northernmost segments. Thalassia testudinum was only present in the two southernmost segments that had the lowest TDN and highest light availability (Kd). Blade %N and %P also frequently exceeded critical values of 1.8% and 0.2%, respectively, especially in the northern segments. Further, δ15N was positively correlated with ammonium, suggesting wastewater as a major N source. The δ13C values indicated a trend of increasing light limitation from south to north, which helps explain the recent catastrophic loss of seagrasses in the northern IRL. Overall, elemental composition reflected high N-availability and seagrass species distributions were relatable to spatial trends in N and light limitation. For effective restoration, resource managers must reduce N-loading to the IRL to diminish HABs and increase light availability. Regular biochemical monitoring of seagrass tissue should also be implemented during restoration efforts.

Current phototherapy practice on Java, Indonesia.

BACKGROUND: In Indonesia, the burden of severe hyperbilirubinemia is higher compared to other countries. Whether this is related to ineffective phototherapy (PT) is unknown. The aim of this study is to investigate the performance of phototherapy devices in hospitals on Java, Indonesia. METHODS: In 17 hospitals we measured 77 combinations of 20 different phototherapy devices, with and without curtains drawn around the incubator/crib. With a model to mimic the silhouette of an infant, we measured the irradiance levels with an Ohmeda BiliBlanket Meter II, recorded the distance between device and model, and compared these to manufacturers' specifications. RESULTS: In nine hospitals the irradiance levels were less than required for standard PT: < 10 µW/cm2/nm and in eight hospitals irradiance failed to reach the levels for intensive phototherapy: 30 µW/cm2/nm. Three hospitals provided very high irradiance levels: > 50 µW/cm2/nm. Half of the distances between device and model were greater than recommended. Distance was inversely correlated with irradiance levels (R2 = 0.1838; P < 0.05). The effect of curtains on irradiance levels was highly variable, ranging from - 6.15 to + 15.4 µW/cm2/nm, with a mean difference (SD) of 1.82 (3.81) µW/cm2/nm (P = 0.486). CONCLUSIONS: In half of the hospitals that we studied on Java the levels of irradiance are too low and, in some cases, too high. Given the risks of insufficient phototherapy or adverse effects, we recommend that manufacturers provide radiometers so hospitals can optimize the performance of their phototherapy devices.

The impact of irradiance on UVB-induced cutaneous immunosuppression: Implications on administering most efficient phototherapy.

BACKGROUND: Ultraviolet B (UVB) is commonly used for treating dermatologic conditions. Recently, high irradiance UVB (HIUVB) has been suggested to be more effective for treating skin conditions as compared to its low irradiance (LI) counterpart. The biological impact of UVB radiation emitted at different irradiance on cutaneous immunity remains obscure. OBJECTIVE: This study aimed to explore the impacts of UVB radiation administered at equivalent fluence (mJ/cm2) but different irradiance (mW/cm2) on cutaneous immune response. METHODS: Cultured bone marrow derived dendritic cell (BMDC) were treated with equivalent fluence of UVB radiation with HIUVB or LIUVB. The phenotypic and functional alterations of BMDCs were documented. Animal models were used to validate the in vitro results in vivo and explore the mechanisms involved. RESULTS: After equivalent fluence of UVB radiation, the HIUVB treated BMDC showed significantly lower MHCII and CD86 expressions, reduced capacity to stimulate T cell proliferation, and enhanced activation of aryl hydrocarbon receptor (AhR)-activated genes as compared to control while their LIUVB treated counterpart showed no significant change. Using animal model, the HIUVB induced significantly higher immune suppressive effect in mice as compared to their LIUVB counterpart after equivalent fluence of UVB treatment. The superior immune suppressive effect of HIUVB over LIUVB radiation was not observed when similar experiments were performed using AhR-deficient mice. CONCLUSION: We propose irradiance played an important role modulating UVB-induced cutaneous immune suppression. Future works on UVB phototherapy, both clinical and research, should incorporate this important parameter into consideration.

Spectral comparison of diffuse PAR irradiance under different tree and shrub shading conditions and in cloudy days.

Spectral Solar Photosynthetically Photon Flux Density (PPFD) (380 to 780 nm) reaching the surface of a plant in different lighting conditions has been analyzed in order to better understand the different photosynthetic performance of plants depending on their spatial situation and the vegetation surrounding. A comparison between the shadow of several trees in a sunny day and the case of a cloudy day in an open space has been studied. Three isolated trees (a palm tree, an olive tree and a shrub oleander) and a tipuana grove have been studied. The study has been developed in Valencia (Spain) during January and February 2017. A portable Asensetek Standard ALP-01 spectrometer with a measurement wavelength range of 380 to 780 nm, has been used. Conditions with higher PPFD received are found to be, apart from those of a sunny day, those for cloudy day (with a spectral maximum in the Green region of the spectrum), and those for individual trees and shrub shadows in a sunny day (with a spectral maximum in the Blue region). The case in which less amount of PPFD is received is that under the shadow of tipuana grove (with a spectral maximum in the Infrared region of the spectrum). In fact the order of magnitude in which the PPFD in a cloudy day exceeds the PPFD under the tipuana grove shade is up to 20.

Variation in the Phototherapy Practices and Irradiance of Devices in a Major Metropolitan Area.

BACKGROUND: Phototherapy (PT) is widely used to prevent and treat severe hyperbilirubinemia and its associated risks for both acute and chronic bilirubin encephalopathy. Intensive PT, recommended for inpatient treatment of hyperbilirubinemia in term and near-term infants, is defined as having a spectral irradiance of ≥30 µW/cm2/nm. OBJECTIVES: We aimed to assess local PT practices by measuring the irradiance of PT devices in local neonatal intensive care units and newborn nurseries. METHODS: The irradiance footprint, including maximum irradiance at the center of the footprint, of 39 PT devices in 7 area hospitals was measured according to current practice in these facilities. RESULTS: The mean ± SD (range) footprint irradiance was 20.7 ± 5.8 (8.8-29.4) µW/cm2/nm. The mean ± SD maximum irradiance at the footprint center for all devices at a mean clinically used treatment distance of 33.1 ± 9.3 (25.5-60.0) cm was 27.8 ± 7.0 (14.7-42.0) µW/cm2/nm. Sixty-two percent of the devices did not meet the minimum recommended spectral irradiance for intensive PT. For the sites without irradiance-based protocols, the maximum irradiance of the devices (n = 33) at the treatment distances was 25.8 ± 6.1 µW/cm2/nm. CONCLUSIONS: Despite established PT guidelines, local protocols and practices vary. Based on an assessment of 7 local hospitals, intensive PT was suboptimal for 62% of devices. Straightforward changes, such as decreasing the distance between an infant and the light source and establishing a consistent irradiance-based protocol, could substantially improve the quality of the intervention.

Factors influencing irradiance of locally fabricated phototherapy devices in Jos, north-central Nigeria.

Locally fabricated phototherapy devices (LFPDs) are widely used in Nigeria for the treatment of neonatal jaundice. Ours was a cross-sectional observational study of all LFPDs in major hospitals in Jos between January and March 2015. We evaluated a total of 24 LFPDs. The irradiance at the level of the baby was in the range of 2-23.9 µW/cm2/nm. Fourteen devices had the recommended irradiance of ≥10 µW/cm2/nm and none had irradiance in the intensive range. Decreasing distance from the baby, presence of reflectors and increasing number of flourecent tubes significantly contributed to higher irradiance. A combination of six tubes, presence of reflectors and a distance of 10 cm from the baby produced a mean irradiance of 23.40 µW/cm2/nm. The irradiance of LFPDs varies widely and can be improved by simple modifications.

Dose Quantification in UV Phototherapy.

Ultraviolet light has long been used to alleviate a number of skin conditions, and its efficacy is well known. However, over-exposure to ultraviolet radiation has a number of detrimental effects and thus it is vital to maintain a dose to skin within the therapeutic window. To maximise treatment gain whilst circumventing potential side-effects of over-exposure requires accurate determination of irradiance and skin-dose. This is complicated by the fact that ultraviolet radiation is essentially absorbed at the skin surface, which means that changing orientation of the patient and source can modulate dose received. In addition, irregular patient shapes mean dose must be carefully calibrated. This chapter focuses on methods of determination of dose, clinical protocols for quantifying radiation dose received and mathematical models for estimating these quantities.

Optimal Temperature and Light Intensity for Improved Mixotrophic Metabolism of Chlorella sorokiniana Treating Livestock Wastewater.

Mixotrophic microalgal growth gives a great premise for wastewater treatment based on photoautotrophic nutrient utilization and heterotrophic organic removal while producing renewable biomass. There remains a need for a control strategy to enrich them in a photobioreactor. This study performed a series of batch experiments using a mixotroph, Chlorella sorokiniana, to characterize optimal guidelines of mixotrophic growth based on a statistical design of the experiment. Using a central composite design, this study evaluated how temperature and light irradiance are associated with CO2 capture and organic carbon respiration through biomass production and ammonia removal kinetics. By conducting regressions on the experimental data, response surfaces were created to suggest proper ranges of temperature and light irradiance that mixotrophs can beneficially use as two types of energy sources. The results identified that efficient mixotrophic metabolism of Chlorella sorokiniana for organics and inorganics occurs at the temperature of 30-40°C and diurnal light condition of 150-200 µmol E·m2·s-1. The optimal specific growth rate and ammonia removal rate were recorded as 0.51/d and 0.56/h on average, respectively, and the confirmation test verified that the organic removal rate was 105 mg COD·l-1·d-1. These results support the development of a viable option for sustainable treatment and effluent quality management of problematic livestock wastewater.