Transport dynamics of SARS-CoV-2 under outdoor conditions.

This study aimed at estimating the transport dynamics of a single severe acute respiratory syndrome corona-virus 2 (SARS-CoV-2)-laden droplet of 1 to 500 µm in diameter at a wind speed from 1 to 4 m/s. Motion dynamics of SARS-CoV-2-laden respiratory droplets under calm or turbulent air conditions were quantified using a combined model. Dalton's law was implemented to estimate their evaporation. One-factor-at-a-time procedure was applied for the sensitivity analysis of model of deposition velocity. The transport distance of the single virus ranged from 167 to 1120 m as a function of the droplet size, wind speed, and falling time. The evaporation times of the droplets ≤ 3 and ≤ 14 µm in diameter were shorter than their settling times from 1.7 m in height at midnight and midday, respectively. Such droplets remained in the air for about 5 min as the droplet nuclei with SARS-CoV-2. The minimum transport distance of the respiratory droplets of 1-15 µm varied between 8.99 and 142 m at a wind speed range of 1-4 m/s, based on their deposition velocity. With their short transport distance, the larger droplet (30 to 500 µm) was not suspended in the air even under the windy conditions. The deposition velocity was found most sensitive to the droplet diameter. The droplets < 15 µm in diameter completely evaporated at midday and the droplet nuclei with the single virus can travel a minimum distance of 500 m under a horizontal wind speed of 3 m/s.

A model for indoor motion dynamics of SARS-CoV-2 as a function of respiratory droplet size and evaporation.

A simplified model has been devised to estimate the falling dynamics of severe acute respiratory syndrome corona-virus 2 (SARS-CoV-2)-laden droplets in an indoor environment. Our estimations were compared to existing literature data. The spread of SARS-CoV-2 is closely coupled to its falling dynamics as a function of respiratory droplet diameter (1 to 2000 µm) of an infected person and droplet evaporation. The falling time of SARS-CoV-2 with a respiratory droplet diameter of about 300 µm from a height of 1.7 m remained almost the same among the Newtonian lift equation, Stokes's law, and our simplified model derived from them so as to account for its evaporation. The evaporative demand peaked at midday which was ten times that at midnight. The evaporating droplets [Formula: see text] 6 µm lost their water content rapidly, making their lifetimes in the air shorter than their falling times. The droplets [Formula: see text] 6 µm were able to evaporate completely and remained in the air for about 5 min as droplet nuclei with SARS-CoV-2.

Falling Dynamics of SARS-CoV-2 as a Function of Respiratory Droplet Size and Human Height.

PURPOSE: The purpose of this study is to quantify the motion dynamics of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). METHODS: Three physical models of Newton's and Stokes's laws with(out) air resistance in the calm air are used to determine the falling time and velocity regimes of SARS-CoV-2 with(out) a respiratory water droplet of 1 to 2000 micrometers (µm) in diameter of an infected person of 0.5 to 2.6 m in height. RESULTS: The horizontal distance travelled by SARS-CoV-2 in free fall from 1.7 m was 0.88 m due to breathing or talking and 2.94 m due to sneezing or coughing. According to Newton's laws of motion with air resistance, its falling velocity and time from 1.7 m were estimated at 3.95 × 10-2 m s-1 and 43 s, respectively. Large droplets > 100 µm reached the ground from 1.7 m in less than 1.6 s, while the droplets ≥ 30 µm fell within 4.42 s regardless of the human height. Based on Stokes's law, the falling time of the droplets encapsulating SARS-CoV-2 ranged from 4.26 × 10-3 to 8.83 × 104 s as a function of the droplet size and height. CONCLUSION: The spread dynamics of the COVID-19 pandemic is closely coupled to the falling dynamics of SARS-CoV-2 for which Newton's and Stokes's laws appeared to be applicable mostly to the respiratory droplet size ≥ 237.5 µm and ≤ 237.5 µm, respectively. An approach still remains to be desired so as to better quantify the motion of the nano-scale objects.

Outer Side of the Nasal Bone Osteoma.

Osteomas are located mostly in the mandible followed by paranasal sinuses such as frontal sinuses, ethmoid air cells, maxillary sinuses and rarely based on nazal cavitiy or turbinate. The osteoma located on outside of nazal bone is extremely rare. The authors report an unusual patient of nasal bone osteoma associated with aesthetic problem on nasal dorsum. Outer side of nasal bone osteoma in large diameter causes aesthetic problems. The authors believe that open rhinoplasty approach is successful in this type of patients.

A new lateral thoracic artery perforator flap design with multiple vascular territories in rats.

BACKGROUND: To describe a new design for an extended lateral thoracic artery (LTA) perforator flap and investigate its anatomical, dynamic, and potential territories. MATERIALS AND METHODS: To assess vascular territories, rats were randomized according to LTA perforator flap type into the surgical groups A, hemidorsal island flap; B, entire dorsal island flap; and C, reduced-size dorsal island flap. RESULTS: On postsurgical day 7, the surviving flap areas were 95%, 92%, and 89% in groups A, B, and C, respectively. Necrosis most commonly occurred in the contralateral LTA territories in groups B and C. The immunoreactivities of intercellular adhesion molecule 1 and vascular endothelial growth factor receptor 2 in dynamic territories, as choke vessel markers, were increased. CONCLUSIONS: We clarified the LTA perforator flap nomenclature and defined its pedicle course and anastomosing patterns; furthermore, we demonstrated that the LTA perforator did not anastomose with its counterpart because of its unidirectional, oblique, and craniocaudal course. The LTA perforator flap was found to be a good model comprising multiple vascular territories and exhibiting continuous necrosis.

Circumflex scapular artery myocutaneous and/or vascularized scapular chimeric flap.

BACKGROUND: Chimeric osteomyocutaneous flaps harvested from the subscapular artery system have been used in clinical practice. We describe the use of a novel circumflex scapular artery myocutaneous and/or vascularized scapular chimeric flap in a rat model and demonstrate optimal skin flap dimensions. MATERIALS AND METHODS: An 8 × 4-cm-rectangular skin flap based on the circumflex scapular artery flap was harvested, and the mean percentage of the surviving flap area and the necrotic area were calculated to be 71% ± 17.9% and 29% ± 17.9%, respectively. Using flap dimensions determined in the first part of our study, a 4 × 3-cm quadrangular portion of skin was marked over the scapula, and the serratus anterior muscle and a portion of the scapular bone were included in our chimeric flap model. RESULTS: The mean percentages of the surviving flap and necrotic areas were 74% ± 6% and 25% ± 6%, respectively. Microangiographic and histologic studies revealed the vascularity of the skin island and identified the branches of the circumflex scapular artery that supplied the bone and muscle. CONCLUSIONS: The circumflex scapular artery myocutaneous and/or vascularized partial scapular chimeric flap may be considered a branch-based chimeric flap and can be an acceptable flap model due to its simplicity, reliability, and consistent vascularity. Furthermore, this flap may have potential applications in studying chimeric flap hemodynamics.

Treating the Golden Implant Visibility on a Paralytic Eye by Using the Capsule Shield Technique.

Static upper eyelid weight loading is a well known treatment option for patients who suffer from paralytic lagophtalmus. Golden implants may cause some complications such as extrusion, postoperative ptosis, visibility of the implant from the skin, infection, or dislocation. Our patients applied to our clinic with discomfort of the implant's easily noticeable visibility in their daily life. They were scheduled the operation programme for reducing visibility of implant.In operation, capsule formation has seen and dissection begun preserving the capsule formation. The capsule has opened on its cranial edge and implant has been removed. By this maneuver, 2 layers of capsule were dissected from surrounding tissues without separating its caudal edges from the upper tarsal fold. These 2 layers were sutured to each other providing strong fibrous shield with the aim of preventing implant visibility. A new pocket has been created under this fibrous shield.Capsule shield technique is provided to replace the implant and prevent revisibilation by using forceful fibrous and highly vascular 2 layers of capsule. This technique seems 1 step ahead than autogenous grafts that require secondary surgical area and bring donor site complications with itself. It does not contain any risk of developing foreign body response and graft infection, unlikely nonautogenous/autogenous graft materials. Also, in the capsule shield technique, operation duration will be shorter and hospitalization period will be shorter compared with techniques using barrier materials because it does not require any additional surgical intervention in donor area. In addition, the authors keep the apeuneurosis in anatomical position and no other new incisions are required. Since no biomaterials are required, this technique also avoids donor site morbidity.