Toxic metals and the risks of sludge from the treatment of wastewater from beryllium smelting.

The release of highly toxic beryllium in sludge (BCS) produced by physico-chemical treatment of beryllium-containing wastewater from Be smelting production has become a growing concern with the widespread use of Be in the defense industry. This work investigated the potential mobility of Be in BCS. The toxicity characteristic leaching procedure (TCLP) of BCS showed that the amount of leached Be was up to 202 mg L-1, which exceeded the regulated limit by nearly 10,000 times. The chemical fractionation analysis further revealed that the excessive amount of Be leached from BCS was contributed to the high content of acid-soluble fraction and reducible fraction of Be, which accounted for over 70% of the Be content. The results obtained from mineralogical automatic analyzer (MLA) showed that gypsum (23.23%) and epidote (19.55%) were the two major mineralogical phases of BCS. Both were small and loosely structured agglomerated particles with a D50 of 6.61 µm and 3.31 µm. ToF-SIMS results revealed that the Be distribution on the surface of BCS particles was relatively dispersed, with no aggregation or encapsulation. Be co-precipitated with gypsum and chlorite in the form of unstable Be(OH)2, which attached to the surface of these small particles. The unstable state of Be and the small size, loose structure and high liberation of the host material phases are the main reasons for the high leaching mobility of Be. The results of the risk assessment indicated that BCS posed an extremely high potential ecological risk, with Be being the most significant contributor.

Novel metallomic profiling and non-carcinogenic risk assessment of botanical ingredients for use in herbal, phytopharmaceutical and dietary products using HR-ICP-SFMS.

Knowledge of element concentrations in botanical extracts is relevant to assure consumer protection given the increased interest in plant-based ingredients. This study demonstrates successful multi-element investigations in order to address the lack of comprehensive profiling data for botanical extracts, while reporting for the first time the metallomic profile(s) of arnica, bush vetch, sweet cicely, yellow rattle, bogbean, rock-tea and tufted catchfly. Key element compositions were quantified using a validated HR-ICP-SFMS method (µg kg-1) and were found highly variable between the different plants: Lithium (18-3964); Beryllium (3-121); Molybdenum (75-4505); Cadmium (5-325); Tin (6-165); Barium (747-4646); Platinum (2-33); Mercury (5-30); Thallium (3-91); Lead (12-4248); Bismuth (2-30); Titanium (131-5827); Vanadium (15-1758); Chromium (100-4534); Cobalt (21-652); Nickel (230-6060) and Copper (1910-6340). Compendial permissible limits were not exceeded. Overall, no evidence of a health risk to consumers could be determined from consumption of the investigated plants at reasonable intake rates. Mathematical risk modelling (EDI, CDI, HQ, HI) estimated levels above safe oral thresholds only for Cd (16%) and Pb (8%) from higher intakes of the respective plant-derived material. Following high consumption of certain plants, 42% of the samples were categorised as potentially unsafe due to cumulative exposure to Cu, Cd, Hg and Pb. PCA suggested a potential influence of post-harvest processing on Cr, Ti and V levels in commercially-acquired plant material compared to wild-collected and farm-grown plants. Moreover, a strong correlation was observed between Pb-Bi, Be-V, Bi-Sn, and Tl-Mo occurrence. This study may support future research by providing both robust methodology and accompanying reference profile(s) suitable for the quality evaluation of essential elements and/or metal contaminants in botanical ingredients.

Evaluation of Picosecond 755-nm Alexandrite Laser With a Diffractive Lens Array on Pore Size Reduction.

OBJECTIVES: Medications, lasers and light therapy have all been shown to transiently minimize pore size. Current research of the 755-nm Alexandrite picosecond laser (Cynosure, MA) on pore size shows differing results regarding the efficacy, with one study of Asian volunteers (Fitzpatrick skin type IV) reporting “marked” improvement of pores, yet another study reporting no significant improvement in pore size in Chinese patients (Fitzpatrick skin type III–IV), causing some contention. This study aims to rectify the discordant results through the examination of the 755-nm Alexandrite picosecond laser on pore size reduction in a sample consisting of Fitzpatrick skin type I–III. METHODS: Patients who received 755-nm Alexandrite picosecond laser treatment for photorejuvenation, (6 mm lens array) with a fluence of 0.71 J/cm2 of the face or head, with at least two treatments over four-week intervals were included in the study. A precision subject imaging system (Canfield VISIA® Complexion Analysis Generation 7, NJ) was used to assess three parameters of pore size (feature count, score, percentile rank) at each time period at right lateral, left lateral and frontal views. A Wilcoxin signed rank test was performed to compare differences between time periods and a mixed model ANOVA was utilized to account for patients who received less than three treatments. Significance level set to P=<0.05. RESULTS: 32 participants met criteria and underwent at least two picosecond laser treatments for photorejuvenation. There was an overall reduction in pore count in approximately 57% of participant data points from times 1 to 2 and 50% reduction from times 2 to 3. There was a 100% pore count reduction observed from baseline compared with the follow-up visit four weeks after the third treatment, at time 4. Further, there was a significant improvement of pores demonstrated by score from times 1 to 3 (Z= -2.197, P=0.028) as well as percentile rank between times 1 and 2 (Z= -2.070, P=0.038) and times 1 and 3 (Z= -2.201, P=0.028). CONCLUSION: Future studies should investigate the longterm effect of 755-nm Alexandrite picosecond laser on pore size reduction as continued patient recruitment and data collection is necessary to effectively discern the 755-nm Alexandrite picosecond laser debate. Thus, prolonged follow up post treatment should be evaluated in order to determine if results are maintained. Nonetheless, the 755-nm Alexandrite picosecond laser shows promising results for the improvement of skin pores thus far. J Drugs Dermatol. 2021;20(12):1302-1306. doi:10.36849/JDD.6199.

Aqueous solubility of beryllium(II) at physiological pH: effects of buffer composition and counterions.

Beryllium ion elicits p53-mediated cell cycle arrest in some types of human cancer cells, and it is a potent inhibitor of GSK3 kinase activity. Paradoxically, Be2+ is regarded to have almost negligible aqueous solubility at physiological pH, due to precipitation as Be(OH)2. This study demonstrates that the interaction of Be2+ with serum proteins greatly increases its effective solubility. In typical serum-supplemented mammalian cell culture medium, Be2+ was soluble up to about 0.5 mM, which greatly exceeds the concentration needed for biological activity. Some biochemical studies require protein-free Be2+ solutions. In such cases, the inclusion of a specific inorganic counterion, sulfate, increased solubility considerably. The role of sulfate as a solubility-enhancing factor became evident during preparation of buffered solutions, as the apparent solubility of Be2+ depended on whether H2SO4 or a different strong acid was used for pH adjustment. The binding behavior of Be2+ observed via isothermal titration calorimetry was affected by the inclusion of sodium sulfate. The data reflect a "Diverse Ion Effect" consistent with ion pair formation between solvated Be2+ and sulfate. These insights into the solubility behavior of Be2+ at physiological and near-physiological pH will provide guidance to assist sample preparation for biochemical studies.

Risk assessment of antimony, barium, beryllium, boron, bromine, lithium, nickel, strontium, thallium and uranium concentrations in the New Zealand diet.

Identifying and monitoring dietary toxicants is an important component of contemporary food safety systems. To characterise their potential dietary risks, analysis was undertaken of 10 elements: antimony, barium, beryllium, boron, bromine, lithium, nickel, strontium, thallium and uranium in 132 different food types. All 10 elements were reported as quantified in aportion of the analysed foods, with prevalence ranging from less than 1% for antimony to 98% for barium. Dietary exposure assessment was undertaken for 10 New Zealand population cohorts using apublished simulated diet, and proportionality of food groups to total exposure identified. Characterisation against health-based guidance values identified no dietary risk from exposures to beryllium, boron, bromine, lithium, strontium and uranium to any of the population cohorts. For antimony and thallium, the exposure range for infants was calculated to exceed the health-based guidance value, and for barium and nickel, all mean exposures were above the health-based guidance value for younger population cohorts. Although some conservatism in applying upper-bound mean exposures reduces the likelihood of asignificant dietary risk, further laboratory method development and analysis of these elements in the New Zealand diet would be beneficial to ensure protection of New Zealand public health.

Evaluation of the Safety and Efficacy of a Picosecond Alexandrite Laser With DLA for Acne Scars in Chinese Patients.

BACKGROUND AND OBJECTIVES: Recently, picosecond laser treatment has been used as an effective treatment for acne scars. To evaluate the efficacy and safety of a picosecond alexandrite laser with a diffractive lens array in the treatment of acne scars in Chinese patients. STUDY DESIGN/MATERIALS AND METHODS: Patients with facial acne scars were treated with a picosecond alexandrite laser in three sessions at 4- to 6-week intervals and followed up for 2 months. Primary outcomes were measured by physicians' blinded evaluation of the acne scar using the ECCA (échelle d'éva physicians'luation clinique des cicatrices d'acné) grading scale. The secondary outcomes included the investigator global assessment (IGA) on the improvement of post-inflammatory erythema (PIE), patients' assessment of improvement on a 4-point scale and of satisfaction on a 5-point scale. Pain scores and adverse effects were also evaluated. RESULT: Twenty patients with Fitzpatrick skin types III and IV were enrolled in the study and completed all treatment and follow-up visits. The mean ECCA scores fell from 197.75 ± 35.26 to 142.00 ± 35.92 (a 28% improvement), and the change was significant (P = 0.000). The mean IGA score of PIE improvement was 3.03 ± 0.75 (0 = no improvement and 4 = 76-100% improvement). On the basis of the patients' self-assessment, the average improvement scores were 2.30 ± 0.98 (0 indicating 0-25% improvement and 3 indicating >75% improvement). In total, 50% and 30% of the patients were "satisfied" and "very satisfied," respectively, with the treatment. The mean pain score was 3.20 ± 0.50 (0 = no pain, 10 = maximum pain) with topical anesthesia. The adverse effects included transient and mild erythema, edema, and scabbing. CONCLUSIONS: Treatment with a picosecond alexandrite laser with a diffractive lens array is effective and safe for acne scars in Chinese patients. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

Removal of unwanted hair: efficacy, tolerability, and safety of long-pulsed 755-nm alexandrite laser equipped with a sapphire handpiece.

Due to the difference in refraction coefficients between air and the corneal epithelium, irradiation of the skin with a light source can lead to reflection of the energy and its leakage to the skin causes epidermal injury. All of which decreases the efficacy of treatment. We evaluated cooling sapphire handpieces' efficacy in decreasing pain and epidermal injuries and enhancing the treatment outcome in laser hair removal. A total of 49 patients with Fitzpatrick skin types of II to IV were treated for laser hair removal on face, limbs, inguinal, and axillary areas with pulsed 755-nm alexandrite laser equipped with a sapphire handpiece and the cooling system. Hair counts were performed by two independent observers at the baseline and 3 months after the final treatment. A marked reduction in hair regrowth was noted 3 months after the final treatment in all body locations studied. Clinical hair reduction was observed and fully assessed. There were no serious side effects with an average pain score of 4.6 out of 40. The cooled sapphire cylinder tip has been shown to minimize epidermal injury and reduce the system energy leaks to the skin.

Thermoluminescence of metallic oxides. Development and applications in Mexico: An overview.

Interest in the study of the thermoluminescence of metallic oxides doped with various elements has been steadily increasing due to the characteristics of these materials and their possible applications in the dosimetry of ionizing radiation. Metal oxides such as zirconium oxide (ZrO2), aluminum oxide Al2O3, titanium oxide (TiO2), hafnium oxide (HfO2) and beryllium oxide (BeO) are very interesting semiconductor materials having a wide band gap with different important applications. Since 1998, in our country we have developed these materials un-doped and doped with various elements, using different preparation methods. These materials have been obtained in powder form, thin films or in pellets made by mixing the TL powder with PTFE. Thermoluminescent and dosimetric characteristics of these materials have been studied and have been used successfully in various applications. It is presented an overview of the development of these materials in Mexico for the past 20 years.

Global patterns of dust and bedrock nutrient supply to montane ecosystems.

A global compilation of erosion rates and modeled dust fluxes shows that dust inputs can be a large fraction of total soil inputs, particularly when erosion is slow and soil residence time is therefore long. These observations suggest that dust-derived nutrients can be vital to montane ecosystems, even when nutrient supply from bedrock is substantial. We tested this hypothesis using neodymium isotopes as a tracer of mineral phosphorus contributions to vegetation in the Sierra Nevada, California, where rates of erosion and dust deposition are both intermediate within the global compilation. Neodymium isotopes in pine needles, dust, and bedrock show that dust contributes most of the neodymium in vegetation at the site. Together, the global data sets and isotopic tracers confirm the ecological significance of dust in eroding mountain landscapes. This challenges conventional assumptions about dust-derived nutrients, expanding the plausible range of dust-reliant ecosystems to include many temperate montane regions, despite their relatively high rates of erosion and bedrock nutrient supply.

Accelerator driven neutron source design via beryllium target and 208Pb moderator for boron neutron capture therapy in alternative treatment strategy by Monte Carlo method.

AIMS: The reactor has increased its area of application into medicine especially boron neutron capture therapy (BNCT); however, accelerator-driven neutron sources can be used for therapy purposes. The present study aimed to discuss an alternative method in BNCT functions by a small cyclotron with low current protons based on Karaj cyclotron in Iran. MATERIALS AND METHODS: An epithermal neutron spectrum generator was simulated with 30 MeV proton energy for BNCT purposes. A low current of 300 µA of the proton beam in spallation target concept via 9Be target was accomplished to model neutron spectrum using 208Pb moderator around the target. The graphite reflector and dual layer collimator were planned to prevent and collimate the neutrons produced from proton interactions. Neutron yield per proton, energy distribution, flux, and dose components in the simulated head phantom were estimated by MCNPX code. RESULTS: The neutron beam quality was investigated by diverse filters thicknesses. The maximum epithermal flux transpired using Fluental, Fe, Li, and Bi filters with thicknesses of 7.4, 3, 0.5, and 4 cm, respectively; as well as the epithermal to thermal neutron flux ratio was 161. Results demonstrated that the induced neutrons from a low energy and low current proton may be effective in tumor therapy using 208Pb moderator with average lethargy and also graphite reflector with low absorption cross section to keep the generated neutrons. CONCLUSIONS: Combination of spallation-based BNCT and proton therapy can be especially effective, if a high beam intensity cyclotron becomes available.

Concentrations of Trace Elements in Hemodialysis Patients: A Prospective Cohort Study.

BACKGROUND: Low concentrations and excessive concentrations of trace elements have been commonly reported in hemodialysis patients, but available studies have several important limitations. STUDY DESIGN: Random sample of patients drawn from a prospective cohort. SETTING & PARTICIPANTS: 198 incident hemodialysis patients treated in 3 Canadian centers. MEASUREMENTS: We used mass spectrometry to measure plasma concentrations of the 25 elements at baseline, 6 months, 1 year, and 2 years following enrollment in the cohort. We focused on low concentrations of zinc, selenium, and manganese and excessive concentrations of lead, arsenic, and mercury; low and excessive concentrations of the other 19 trace elements were treated as exploratory analyses. Low and excessive concentrations were based on the 5th and 95th percentile plasma concentrations from healthy reference populations. RESULTS: At all 4 occasions, low zinc, selenium, and manganese concentrations were uncommon in study participants (≤5.1%, ≤1.8%, and ≤0.9% for zinc, selenium, and manganese, respectively) and a substantial proportion of participants had concentrations that exceeded the 95th percentile (≥65.2%, ≥74.2%, and ≥19.7%, respectively). Almost all participants had plasma lead concentrations above the 95th percentile at all time points. The proportion of participants with plasma arsenic concentrations exceeding the 95th percentile was relatively constant over time (9.1%-9.8%); the proportion with plasma mercury concentrations that exceeded the 95th percentile varied between 15.2% and 29.3%. Low arsenic, platinum, tungsten, and beryllium concentrations were common (>50%), as were excessive cobalt, manganese, zinc, vanadium, cadmium, selenium, barium, antimony, nickel, molybdenum, lead, and chromium concentrations. CONCLUSIONS: There was no evidence that low zinc, selenium, or manganese concentrations exist in most contemporary Canadian hemodialysis patients. Some patients have excessive plasma arsenic and mercury concentrations, and excessive lead concentrations were common. These findings require further investigation.

Control of hair growth using long-pulsed alexandrite laser is an efficient and cost effective therapy for patients suffering from recurrent pilonidal disease.

Pilonidal sinus (PNS) and its surgical management have a profound impact on hospital resources in terms of finances and productive man-hours. Surgical treatment has been the mainstay of treatment of both acute and chronic pilonidal sinus but recurrence is common. The control of hair growth in the sinus region plays an important role in preventing recurrence. Here, we discuss our experience of treating 19 patients suffering from recurrent pilonidal sinus with laser depilation and its long-term cost effectiveness. This is a retrospective study on patients who had recurrence of pilonidal sinus following multiple surgical treatments. They were treated using long-pulsed alexandrite laser for depilation in the sinus area, an outpatient procedure. Their clinical characteristics and outcomes were then evaluated. There was a significant reduction in hair density after laser treatment (p < 0.001). The disease-free period after laser treatment was significantly longer than that one after surgical treatment (p < 0.001). The average cost of repeated surgical treatment per disease-free month was significantly higher than that of laser treatment (p < 0.001). Evidence suggests the role of natal cleft hair growth in the evolution of the pilonidal disease; therefore, control of hair growth should be considered as an adjunct to the initial treatment via surgery. Compared to surgical treatment of recurrences, laser depilation is an efficient and cost-effective method of preventing recurrence and reducing morbidity and loss of man-hours. We suggest that laser depilation of the pilonidal sinus should be funded by clinical commissioning groups.

PROPERTIES OF THE BEOSL DOSIMETRY SYSTEM IN THE FRAMEWORK OF A LARGE-SCALE PERSONAL MONITORING SERVICE.

The Individual Monitoring Service of the Helmholtz Zentrum München is currently using the BeOSL dosimetry system for monitoring ∼15 000 persons per month. This dosimetry system has a modular structure and represents a complete new concept on handling dosemeters in a large-scale dosimetry service. It is based on optically stimulated luminescence dosemeters made of beryllium oxide. The dosimetric and operational properties of the system are shown and discussed.

Timing and climate forcing of volcanic eruptions for the past 2,500 years.

Volcanic eruptions contribute to climate variability, but quantifying these contributions has been limited by inconsistencies in the timing of atmospheric volcanic aerosol loading determined from ice cores and subsequent cooling from climate proxies such as tree rings. Here we resolve these inconsistencies and show that large eruptions in the tropics and high latitudes were primary drivers of interannual-to-decadal temperature variability in the Northern Hemisphere during the past 2,500 years. Our results are based on new records of atmospheric aerosol loading developed from high-resolution, multi-parameter measurements from an array of Greenland and Antarctic ice cores as well as distinctive age markers to constrain chronologies. Overall, cooling was proportional to the magnitude of volcanic forcing and persisted for up to ten years after some of the largest eruptive episodes. Our revised timescale more firmly implicates volcanic eruptions as catalysts in the major sixth-century pandemics, famines, and socioeconomic disruptions in Eurasia and Mesoamerica while allowing multi-millennium quantification of climate response to volcanic forcing.

Co-administration of adjuvants along with Moringa oleifera attenuates beryllium-induced oxidative stress and histopathological alterations in rats.

CONTEXT: Moringa oleifera Lam. (Moringaceae) is a rich source of antioxidants. All parts of the plant are medicinally important and have been used as traditional medicine for a variety of human ailments in India. OBJECTIVE: Therapeutic efficacy of adjuvants with M. oleifera (MO) root extract was investigated against beryllium-induced oxidative stress. MATERIALS AND METHODS: Hydroalcoholic (50% v/v) root extract of M. oleifera (150 mg/kg, p.o.) alone and combinations of M. oleifera with either piperine (2.5 mg/kg, p.o.) or curcumin (5.0 mg/kg, p.o.) daily for 1 week were administered in experimental rats against beryllium toxicity (1.0 mg/kg, i.p. daily for 5 weeks). Oxidative stress parameters including blood sugar, G-6-Pase in liver, and DNA damage were analyzed. Histopathological changes in liver and kidney were also observed. RESULTS: Beryllium enhanced lipid peroxidation (LPO), depleted reduced glutathione (GSH) and antioxidant enzymes activities, decreased blood sugar and G-6-Pase activity, and did not damage DNA. Histologically, liver was observed with structural loss and disintegration of hepatocytes, heavy vacuolation in hepatocytes, and kidney was observed with constriction of glomeruli and hypertrophy in epithelial cells of uriniferous tubules. Therapy of M. oleifera with piperine was effective; however, combination of M. oleifera with curcumin showed better therapeutic effect by reduction of LPO, elevated GSH level, maintained antioxidant enzymes activities, restored blood sugar, and G-6-Pase activity in liver together with almost normal histoarchitecture of liver and kidney. DISCUSSION AND CONCLUSION: Curcumin enhanced therapeutic efficacy of M. oleifera root extract and showed better antioxidant potential against beryllium toxicity.

The radioactivity of seasonal dust storms in the Middle East: the May 2012 case study in Jordan.

Dust storms in the Middle East are common during spring. Some of these storms are massive and carry a large amount of dust from faraway regions, which pose health and pollution risks. The huge dust storm event occurred in early May, 2012 was investigated for its radioactive content using gamma ray spectroscopy. Dust samples were collected from Northern Jordan and it was found that the storm carried a large amount of both artificial and natural radioactivity. The average activity concentration of fallout (137)Cs was 17.0 Bq/kg which is larger than that found in soil (2.3 Bq/kg), and this enrichment is attributed to particle size effects. (7)Be which is of atmospheric origin and has a relatively short half-life, was detected in dust with relatively large activity concentrations, as it would be expected, with an average of 2860 Bq/kg, but it was not detected in soil. Despite the large activity concentration of (7)Be, dose assessment showed that it does not contribute significantly to the effective dose through inhalation. The concentrations of the primodial nuclides (40)K, (232)Th and (238)U were 547, 30.0 and 49.3 Bq/kg, respectively. With the exception of (40)K, these were comparable to what was found in soil.

Relative TL and OSL efficiency to protons of various dosimetric materials.

Thermoluminescence (TL) and optically stimulated luminescence (OSL) are the well-known phenomena used for passive methods of dose measurements. TL and OSL detectors are frequently used in the dosimetry of cosmic radiation in space and of particle radiotherapy beams. However, the relative TL/OSL efficiency, which is defined as a ratio of the emitted light intensity per unit dose for a given radiation type, to the same quantity for the reference gamma radiation is not constant and depends on radiation type and energy. In the present work several types of TL and OSL dosimetric materials, including lithium fluoride (LiF), aluminium oxide, beryllium oxide and lithium aluminate, were tested with protons. The measurements were realised exploiting the 60-MeV proton beam of the AIC-144 cyclotron in the Proton Eye Radiotherapy Facility at Institute of Nuclear Physics (IFJ PAN). The influence of proton energy on the relative efficiency and other TL/OSL characteristics of the studied detector types was presented.

Automatic neutron dosimetry system based on fluorescent nuclear track detector technology.

For the first time, the authors are describing an automatic fluorescent nuclear track detector (FNTD) reader for neutron dosimetry. FNTD is a luminescent integrating type of detector made of aluminium oxide crystals that does not require electronics or batteries during irradiation. Non-destructive optical readout of the detector is performed using a confocal laser scanning fluorescence imaging with near-diffraction limited resolution. The fully automatic table-top reader allows one to load up to 216 detectors on a tray, read their engraved IDs using a CCD camera and optical character recognition, scan and process simultaneously two types of images in fluorescent and reflected laser light contrast to eliminate false-positive tracks related to surface and volume crystal imperfections. The FNTD dosimetry system allows one to measure neutron doses from 0.1 mSv to 20 Sv and covers neutron energies from thermal to 20 MeV. The reader is characterised by a robust, compact optical design, fast data processing electronics and user-friendly software.

Radiological design aspects of the National Ignition Facility.

The National Ignition Facility (NIF) has been designed to accommodate some challenging radiological conditions. The high prompt neutron source (up to 1.6 × 10(19) neutrons per shot) results in the need for significant fixed shielding. Concrete shielding approximately 2 m thick is used for the primary (target bay) shield. Penetrations in this shield, including those required for 192 laser beams, utilities, diagnostics, and 19 shielded personnel access doors, make the design challenging. An additional 28 shield doors are part of the secondary shield. In addition, the prompt neutron pulse results in activated air within the target bay, requiring special ventilation considerations. Finally, targets can use a number of hazardous and radioactive materials including tritium, beryllium, and depleted uranium (the latter of which results in the generation of small quantities of fission products). Frequent access is required to the associated potentially contaminated volumes for experimental setup, facilitating the need for local exhaust ventilation to manage these hazards. This paper reviews some of these challenges, design considerations, and the engineering solutions to these design requirements.