Direct Impaction Research Articles

Numerical investigation on the interaction characteristics between the gaseous detonation wave and the water droplet

In this paper, the interaction characteristics between the gaseous detonation and the water droplet are numerically investigated, utilizing a modified compressible two-phase flow model coupling with detailed hydrogen-oxygen chemistry. Firstly, an analysis is conducted on the propagation behaviors of the cellular detonation obstructed by the droplet. It is found that the cellular detonation undergoes reflection, diffraction, local extinction, and re-ignition upon the obstruction, and these behaviors vary with the droplet relative positioning with multi-dimensional structures of the cellular detonation, particularly in terms of the extinction degree caused by the diffraction and the relative positioning of the re-ignition region. Further, the droplet deformation characteristics are detailly analyzed. It has been revealed that the deformation behavior of the shocked droplet under planar detonation is consistent with that under high-speed airflow. However, for the droplet shocked by the cellular detonation, several windward surface pits are induced due to impaction from transverse shocks and direct hitting of the triple-point. The emergence of these pits notably precedes the onset of surface instabilities caused by high-speed airflow erosion. Further investigation has revealed that post-detonation flow, through the entrainment effect of the central pit, progressively penetrates and segregates the droplet into upper and lower segments, and this penetrating effect heavily depends on the droplet relative positioning. Moreover, the side pit, whose presence is significantly determined by whether there is direct impaction of the triple-point on the droplet windward side, is crucial for the deformation around the droplet equator and the subsequent shedding of smaller droplets.

Sensitive and highly rapid electrochemical measurement of airborne coronaviruses through condensation-based direct impaction onto carbon nanotube-coated porous paper working electrodes

Rapid detection of indoor airborne viruses is critical to prevent the spread of respiratory diseases. Herein, we present sensitive, highly rapid electrochemical measurement of airborne coronaviruses through condensation-based direct impaction onto antibody-immobilized, carbon nanotube-coated porous paper working electrodes (PWEs). Carboxylated carbon nanotubes are drop-cast on paper fibers to make three-dimensional (3D) porous PWEs. These PWEs have higher active surface area-to-volume ratios and electron transfer characteristics than conventional screen-printed electrodes. The limit of detection and detection time of the PWEs for liquid-borne coronaviruses OC43 are 65.7 plaque-forming units (PFU)/mL and 2 min, respectively. The PWEs showed sensitive and rapid detection of whole coronaviruses, which can be ascribed to the 3D porous electrode structure of the PWEs. Moreover, water molecules condense on airborne virus particles during air sampling, and these water-encapsulated virus particles (<4 µm) are impacted on the PWE for direct measurement without virus lysis and elution. The whole detection takes ∼10 min, including air sampling, at virus concentrations of 1.8 and 11.5 PFU/L of air, which can be due to the highly enriching and minimally damaging virus capture on a soft and porous PWE, demonstrating the potential for the rapid and low-cost airborne virus monitoring system.

Microscale flow dynamics and particle capture in scleractinian corals: I. Role of the tentacles

The size, shape, and arrangement of tentacles in scleractinian coral polyps are likely to affect particle capture yet have not been investigated in a systematic way. Morphometric measurements of tentacles of several coral species found in the Caribbean Sea were taken from macro-photographs, and from these, models were constructed in three postures: straight, upstream-facing, and downstream-facing. These models were placed in a flume to video the flow paths of particles around them. Video analysis indicates tentacles, and their specific postures, have a dramatic effect on micro-flow patterns. The expanded soft tissue tentacles, and their specific postures, greatly increase probability of particle capture by direct impaction, inertial impaction, and gravitational deposition. All tentacle postures cause increased retention time relative to freestream travel in their immediate proximity, as well as increasing both contact with the tentacle surface, and tumbling of particles. Straight and upstream-facing tentacles deflect particles downward to their base, while downstream-facing tentacles deflect particles upwards. When results from individual tentacles are considered in geometric combination, the secondary radial symmetry of the tentacular whorls in simple coral polyps appears to be an optimal strategy to filter suspended particulate material in an oscillating and omni-directional flow environment. In meandrine corals, the hedgerows of straight and curved tentacles appear to draw particles downward, retain them, and direct them onto the oral feeding areas below the thecal ridges. The size, shape, and arrangement of tentacles are thus of key importance in understanding suspension feeding in scleractinian corals.

Anterior Shoulder Instability in a Young Individual with Concomitant Coracoid Process Fracture Treated with the Latarjet Procedure – A Rare Case Report

Coracoid fracture occurs with shoulder instability due to direct humeral head impaction. Incidence coracoid fracture with shoulder dislocation is rare amounts to 0.8-2%. We encountered clinical challenge of unique combination of both shoulder instability and coracoid fracture. This technical note will describe the treatment of the same. A 23-year-old male suffering from recurrent shoulder dislocation sustained coracoid fracture. Further evaluation showed glenoid defect of 25%. Magnetic resonance study showed on track lesion with Hill-Sach lesion of 9 mm, labral defect anteriorly with no associated rotator cuff tear. The patient was managed with open Latarjet procedure with fracture coracoid fragment with conjoint tendon as graft. Our purpose of reporting this technical note is to provide an option of dealing both instability and coracoid fracture in single sitting and usage of coracoid fractured fragment as an excellent graft of choice in acute presentation. However, certain limitations such as adequacy of graft in size and shape do exist operating surgeon which must be aware of the same.

Splenic injury during colonoscopy: modern treatment approach and splenic salvage.

Splenic injury is a rare complication of colonoscopy, estimated to occur in 0.020 to 0.034% of procedures, with a 30-day mortality of 3.6% (1-3). Of the three major severe adverse events during colonoscopy (perforation, bleeding, and splenic injury), splenic injury has the highest mortality but is rarest (1). The spleen is attached to the colonic splenic flexure by the splenocolic ligament, suggesting that manipulation of the colon during colonoscopy may cause direct tension or impaction on the spleen and splenic hilum as the mechanism of injury (2,3). Patients typically present within 24 hours of colonoscopy with severe abdominal pain and peritonism, and may be haemodynamically unstable (2). The majority of published cases of high-grade splenic injury due to colonoscopy have been managed with splenectomy (2,3), however smaller numbers have been managed with embolization and conservative measures (3). Modern treatment options for splenic injury due to colonoscopy can be classified into con- servative, endovascular, and surgical management (3). Conservative management involves inpatient moni- toring, with analgesia, intravenous fluids, and blood transfusion (2,3). Endovascular treatment is splenic artery embolization, typically with deployment of coils into the splenic artery proximal to the splenic hilum or into a single splenic artery branch in cases with an isolated focal injury (2-4). Surgical management is principally laparotomic splenectomy (2,3). In modern treatment protocols, splenectomy is usually reserved for unstable patients who require emergent laparotomy (4). Given the similarity in mechanism between splenic injuries due to blunt trauma and those due to colonoscopy, it may be helpful to conceptualize splenic injuries due to colonoscopy according to the American Association for the Surgery of Trauma (AAST) grading system (5). After institutional ethical approval, electronic medical records over a 10-year period (2012-2022) were searched to identify all patients treated for splenic injury due to colonoscopy, with the following inclusion criteria: • Splenic laceration diagnosed on computed tomography (CT). Colonoscopy within 72 hours of CT diagnosis. • Absence of blunt external traumatic incident between colonoscopy and diagnosis. Patient demographic information, past surgical history, colonoscopy indication, splenic injury grading, treatment and outcome data were analysed. Two males and 3 females were included, with median age of 63 years (range: 40-72), and four had undergone previous abdominal surgery (Table 1) (Figure 1). AAST injury grades were II to V. One patient with an AAST II injury was treated conservatively without requiring embolization or splenectomy. Three patients with AAST III-V injuries were treated primarily with splenic artery embolization, with one patient undergoing splenectomy 2 weeks later due to increased haematoma on CT. One patient with AAST III injury was treated conservatively but then underwent splenectomy 6 days later due to clinical rebleeding. All patients in the cohort survived, and 3 of 5 achieved splenic salvage. The spleen has important immune and non-immune functions, as the main filter of blood-borne pathogens, antigens, and red blood cells and patients post- splenectomy have increased life-long risk of infection(6). Embolization preserves splenic function via collateral arterial supply and splenectomy may therefore be best reserved for patients who require emergent laparotomy or where conservative and endovascular management have failed. In the present cohort, 3 of 5 patients were able to avoid splenectomy, higher than in previous published reports (47-69% splenectomy rate) (2,3). The higher splenectomy and mortality rates in previous reports may be due to publication bias favouring severe cases. As a rare complication of colonoscopy, splenic injury requires prompt diagnosis and management to minimize mortality. All patients in the present cohort survived, 3 of 5 with splenic salvage. A treatment protocol utilizing conservative management for low-grade injuries and embolization for high-grade injuries may optimise rates of splenic salvage with long-term public health benefits. This paper has not been presented previously at a conference and is not under consideration by any other journal for publication. The authors have no conflicts of interest to declare. This research was not supported by any funding.

Possible reasons for the regrettable results of patency of an inside stent in endoscopic transpapillary biliary stenting.

Endoscopic biliary decompression is a minimally invasive procedure for cholestasis since the first endoscopic retrograde cholangiopancreatography-guided biliary stenting performed by Soehendra and Reynders-Frederix. Among the endoscopic biliary decompression, endoscopic transpapillary biliary stenting (EBS), is a mainstream choice and presently has two methods of placement: stenting above the sphincter of Oddi (SO) (suprapapillary) and stenting across the SO (transpapillary). Stent patency is the most important concern for patients, endoscopists and physicians because it can affect both the life prognosis and treatment schedule of patients. Biliary stent occlusion can occur because of several factors. Among them, direct food impaction, biofilm formation, and sludge formation play important roles and are presumed to be theoretically overcome by EBS above the SO. Thus, EBS above the SO is expected to result in a longer patency than EBS across the SO. In the literature, there have been six comparative studies on EBS for distal biliary obstruction in which the stent was placed above or across the SO, including two randomized controlled trials (RCTs) with negative results of stenting above the SO. With respect to EBS for hilar biliary obstruction, there have been no RCTs, whereas four retrospective comparative studies with negative results and four retrospective comparative studies showing positive results of stenting above the SO have been reported. In this review, we focused on EBS above and across the SO, and summarized the positive and negative results of the two types of stenting to promote effective clinical practice and to provide a basis for future studies.

Assessment of indoor air quality in geriatric environments of southwestern Europe

The objective of this study was to evaluate physical–chemical and microbial indicators of indoor air quality in three nursing houses (NHs) located in rural areas of the northeast of Portugal. The parameters were measured during two campaigns (winter and summer), twice a day, and in four distinct spaces for spatial variability assessment: dining room, living room, double bedroom and outdoor of the NHs. Physical–chemical indicators were assessed by using a Graywolf IQ 610 probe. Airborne microbial levels were evaluated by direct impaction to the culture media, and subsequently, the microorganisms were identified molecularly. Mean concentrations of physical–chemical (with the exception of total volatile organic compounds, TVOCs) and microbial indicators did not exceed the legal limits. Overall, in all NHs, the indoor-to-outdoor (I/O) concentration ratios of chemical and biological pollutants were ≤ 1 in the summer, while in the winter were > 1. Bacillus, Micrococcus and Staphylococcus were the dominant bacterial genera, and Aspergillus, Cladosporium and Penicillium were the dominant fungal genera. The diversity of species was higher in summer. The main results suggest that a good air quality prevails in all studied spaces, although conditions less desirable have been identified in winter, indicating the need to deepen the study of air quality in these places, since these are occupied by elderly people who are more susceptible to infections.

Assessment of AERMOD modeling system for application in complex terrain in Pakistan

Atmospheric dispersion models based on Gaussian plume formulation are widely used for regulatory purposes in flat terrain. In this paper, the application of an advanced Gaussian plume modeling system, AERMOD, has been investigated over complex terrain setting through a field tracer test conducted in April 2018 near Islamabad, Pakistan. The model was validated through short term (2 h) release from a point elevated non buoyant source of SF6. The hourly averaged concentrations were measured at 47 discrete sampling points. The mesoscale meteorological model, WRF was coupled with AERMOD to provide hourly surface and upper boundary layer meteorological parameters. The statistical evaluation of model was carried out using Fractional Bias (FB) and Normalized Mean Square Error (NMSE). The quantile-quantile (Q-Q) plot was used to assess model's ability to follow the observed concentration distribution. For this field tracer test the model over-predicted ground level concentrations at the receptors close to the source and underestimated at the receptors located in a valley and far away from the source. Moreover, AERMOD overestimated the concentration at receptors which were at the point of direct impaction of plume and ridge. Overall, the model under-predicted the ground level concentration within a factor of two (FB = 0.63) for this field tracer test. It was found that the model better simulated the higher concentrations which are of primary interest for regulatory purposes.

Synthesis of Ge and Si nanoparticles by spark discharge

The production of airborne nanoparticles by multi gap spark discharge generators is shown to be feasible for semiconductors on the example of erosion germanium and silicon electrodes in inert atmosphere. Pure silicon and germanium crystalline nanoparticles with the mean diameter less than 15 nm combined in submicron agglomerates were obtained. Since the presence of residual oxygen in the setup partially oxidized silicon nanoparticles and core-shell germanium structures with pure Ge core and oxidized shell were also observed in the samples. This continuous nanoparticles production technique enables direct impaction of prepared nanoparticles onto a liquid or substrate for applications in the fields of electronics, biomedicine and energetics.

Design of high efficiency PVDF-PEG hollow fibers for air filtration of ultrafine particles

This study reveals as the first attempt to apply hollow fibers for air filtration of ultrafine particles. Different from symmetric nano-fiber filters and non-woven fabrics, asymmetric polyvinylidene fluoride – polyethylene glycol (PVDF-PEG) hollow fibers with high gas permeances have been developed by the dry-jet wet-spinning process. The addition of high molecular weight PEGs in spinning dopes facilitates the formation of loosely connected cross-section and porous outer skin, thus enhances the gas permeance for air filtration. Under the inside-out testing mode, all PVDF-PEG hollow fibers display excellent filtration efficiency of 99.999% against polydispersed NaCl particles with a geometric mean size of ~30nm. Since permeance increases with an increase in PEG molecular weight in spinning dope, the PVDF-PEG hollow fiber with a PEG molecular weight (MW) of 12,000Da possesses the highest quality factor because it has the highest permeance and lowest transmembrane pressure. However, the PVDF-PEG hollow fiber with a PEG MW of 8000Da has the best mechanical properties. Under the dead-end filtration, the filtration efficiency increases with an increase in air flow rate. This trend is contrary to the findings observed in the flat and symmetric fibrous filtration. The asymmetric structure in the cross-section of the newly developed hollow fibers may enhance aerosol deposition via direct impaction and Brownian motion at high flow rates. The dead-end filtration results also show that the quality factor is higher at a lower flow rate. Similarly, the cross-flow filtration results show that the hollow fiber modules operated at low cross-flow ratios have high quality factors. Therefore, it is preferred to operate the newly developed PVDF-PEG hollow fiber at a low flow rate or low cross-flow ratio. This study may provide useful insights for developing hollow fibers for air filtration with the optimal operation conditions.

On the enhancement of particle deposition in turbulent channel airflow by a ribbed wall

The particle deposition at a vertical wall roughened by transverse square bars placed at a small spacing between them is investigated using large-eddy simulation of the turbulent flow in a ribbed channel with the gravity aligned in the flow direction together with Lagrangian particle-tracking. It is found that the particle deposition coefficient is substantially increased in the presence of roughness elements, exhibiting a weaker dependence on the variation of particle response time relative to the case of smooth channel. The enhancement ratio of particle deposition varies from three for the larger size particles to about 400 for the smaller particles examined here. The friction-weighted enhancement ratio of particle deposition is higher than unity for all particle sets, indicating that the present ribbed channel configuration efficiently increases particle deposition with respect to the increase in energy losses. The rise in the particle deposition coefficient at the rough surface is closely related to the direct inertial impaction and interception mechanisms. The population of particles depositing at the rear surface of the square bars is very small, revealing that an enlargement of the effective deposition area is not necessarily translated to a similar augmentation of particle removal.

Primary exploration for radial nerve palsy associated with unstable closed humeral shaft fracture.

The treatment of radial nerve palsy caused by closed humeral shaft fracture is a matter of debate. The purpose of this study is to evaluate the outcome of early surgical management of radial nerve palsy in patients with unstable closed humeral shaft fractures and to determine whether patients with this injury should be surgically explored. Medical records of 15 consecutive patients who had undergone open reduction and internal fixation for unstable closed humeral shaft fractures were reviewed. Injury mechanisms, radiographs, intraoperative findings of the injured nerve, and clinical improvement were analyzed. Of the 15 patients, two were injured during simple falls, two during baseball pitching, one by a fall from a height, one during skiing, and one by direct machine impaction during work. Fracture locations were middle humerus in six patients, middle-distal in eight patients, and middle-proximal in one patient. Fracture patterns were transverse fracture in six patients, butterfly segment fracture in four patients, oblique segment fracture in three patients, and spiral fracture in two patients. Eleven patients showed macroscopically intact nerves, and four had total nerve transection. All four patients with total nerve transection were injured in traffic accident. Of these four patients, one showed comminuted fracture with butterfly fragment on the middle-distal shaft and the other three showed displaced transverse fracture on the middle to middle-distal shaft area. Transected nerves were directly repaired in two patients. In the other two patients, humerus shortening and nerve grafting were performed because of mangled nerve endings. All patients who had intact nerves showed fully recovered function at the last follow-up. For radial nerve palsy accompanied by unstable humeral shaft fracture, primary exploration of the radial nerve and open reduction and plate fixation of the fracture should be considered as a treatment of choice. High-energy trauma, fracture location at the middle-distal humerus, and simple transverse fracture or comminuted fracture with butterfly fragment seems to be risk factors for radial nerve transection.

Rapid Removal of Carbofuran from Aqueous Solution by Pulsed Corona Discharge Treatment: Kinetic Study, Oxidative, Reductive Degradation Pathway, and Toxicity Assay

This work demonstrates the application of plasma generated by pulsed corona discharge for the rapid degradation of carbofuran from aqueous solution. Carbofuran with a concentration of 0.5 mg/L to 30 mg/L was effectively removed within 4 to 10 min of treatment time, at 101.5 W input power. Degradation yield (2.95 g/kWh) was much higher for 10 mg/L carbofuran concentration compared to degradation yield (0.37 g/kWh) for 0.5 mg/L carbofuran. The effect of pulsed voltage, pulsed frequency, initial pesticide concentration, pH, and effect of radical scavengers (HCO3–, CO32–, and humic acid) was also investigated in detail. Appearance of some key intermediates confirmed the possibility of formation of some demethylated products due to direct electron impaction during degradation process. Seven intermediates were identified, and possible oxidation and reduction mechanism of carbofuran degradation pathway was proposed. Microalgae ecotoxicity study confirmed the complete detoxification of carbofuran after 14 min cor...

Subradiographic Foot and Ankle Fractures and Bone Contusions Detected by MRI in Elite Ice Hockey Players

Background: In ice hockey players, serious bone injuries in the foot and ankle, especially those attributed to impact from the moving puck, may be radiographically occult and underrecognized. Purpose/Hypothesis: The purpose of this research was to study foot and ankle bone injuries detected with magnetic resonance imaging (MRI) that occurred in elite hockey players. The hypothesis was that these injuries predominate medially, especially when caused by the impact from the puck, and are associated with prolonged lost playing time. Study Design: Case series; Level of evidence, 4. Methods: Three independent observers, blinded to the mechanism of injury, retrospectively reviewed foot and ankle MRI examinations acquired after 31 acute injuries that occurred in 27 elite ice hockey players who had no radiographically visible fractures. Bone abnormalities were classified as fractures or varying degrees of contusion based on predetermined definitions. Interobserver agreement was analyzed with kappa statistics. The association between the injury mechanism and the bones involved was examined with the Fisher exact test. A t test was applied to determine if MRI evidence of a severe bone injury (defined as either a fracture or a high-grade bone contusion) was associated with longer recovery times, when return-to-play information was available. Results: The observers identified at least 1 bone injury in 27 of the 31 MRI examinations, including 10 with radiographically occult fractures. Agreement among the 3 observers for injury categorization was substantial (κ = 0.76). Seventeen injuries were caused by a direct blow (15 from a moving puck, 2 from an uncertain source), resulting in 6 fractures and 6 high-grade bone contusions, with 14 of the 17 involving a medial bone (medial malleolus, navicular, or first metatarsal base). Compared with other mechanisms, direct impaction was statistically more likely to result in a severe bone injury and to involve the medial foot and ankle. In 20 injuries where return-to-play information was available, players with severe bone injuries missed a mean of 10.6 games compared with 2.4 games for other players (P = .05). Conclusion: MRI can show severe bone injuries that are not visible radiographically in ice hockey players. Most fractures and high-grade contusions involve the medial ankle and midfoot bones, can be caused by direct blows from the puck, and are associated with prolonged recovery times.

Coupled LBM-FVM-CA simulation of particle deposition and removal processes on tubes

A numerical model was proposed to simulate the fouling processes on the tubes, which contained the evolution of the fouling shape and the particle deposition/removal mechanisms. Firstly, the coupled lattice Boltzmann method (LBM) and finite volume method (FVM) was established to simulate the air flow. The flow around the tubes was simulated by the LBM due to its convenience in complex boundary conditions. The downstream flow was simulated by the FVM to save the computational source. A reconstruction operator was derived for the information transfer from macroscopic parameters to multiple-relaxation-time LBM. The cellular automata model, energy conservation model and moment analysis were included to simulate the particle motion, collision, deposition and removal. Then, because the time step in the simulation was several orders of magnitude shorter than the real fouling time, a time ratio was proposed for the conversion between simulation and real time. Finally, the evolutions of the fouling shapes along with time for different particle diameters and inlet velocities were simulated and analyzed. The results showed that the proposed coupled model can be used to study the particle deposition, removal and the changing of the fouling layers. When the mass concentration was the same, the fouling of small particle grew faster. The fouling area grew exponentially with time. It grew rapidly in the beginning, then grew slower and finally reached an asymptotic balance value. When the particle concentration was specified, the fouling rate first grew with and then decreased with the increasing inlet velocity. Therefore, there was a velocity range in which the fouling rate was high. As for the shape of the fouling layer, the removal was severe on the windward side, but the direct impaction of the particles formed the cone-shaped fouling layers. The cone-shape changed the air flow and stopped the deposition on the windward side. The fouling layers grew on the entire leeward side of the tubes and finally stopped when the removal was equal to the deposition. The simulated fouling shape was compared with the real picture of the fouling on a tube of an economizer and the fouling shapes on the leeward side coincided well with each other. The growth of the fouling mass was also compared with the existing experiment. The simulated mass had the same trend with the experiment. This demonstrated that the time ratio can be used to convert the time scale. The distribution of the particle sizes and the properties of the real particles should be considered in the future works.

Airflow, transport and regional deposition of aerosol particles during chronic bronchitis of human central airways.

In the present study, the effects of airway blockage in chronic bronchitis disease on the flow patterns and transport/deposition of micro-particles in a human symmetric triple bifurcation lung airway model, i.e., Weibel's generations G3-G6 was investigated. A computational fluid and particle dynamics model was implemented, validated and applied in order to evaluate the airflow and particle transport/deposition in central airways. Three breathing patterns, i.e., resting, light activity and moderate exercise, were considered. Using Lagrangian approach for particle tracking and random particle injection, an unsteady particle tracking method was performed to simulate the transport and deposition of micron-sized aerosol particles in human central airways. Assuming laminar, quasi-steady, three-dimensional air flow and spherical non-interacting particles in sequentially bifurcating rigid airways, airflow patterns and particle transport/deposition in healthy and chronic bronchitis (CB) affected airways were evaluated and compared. Comparison of deposition efficiency (DE) of aerosols in healthy and occluded airways showed that at the same flow rates DE values are typically larger in occluded airways. While in healthy airways, particles deposit mainly around the carinal ridges and flow dividers--due to direct inertial impaction, in CB affected airways they deposit mainly on the tubular surfaces of blocked airways because of gravitational sedimentation.

Patellotibial Contusions

Patellotibial contusions are a recently described contusion pattern in anterior cruciate ligament (ACL) tears. The purposes or our study were to determine if patellotibial contusions are specific to ACL injuries, determine the internal derangements in patients demonstrating this contusion, and suggest a mechanism of injury. We conducted a retrospective search of radiology reports over a 6-year period to identify patients with patellar edema described on magnetic resonance (MR) imaging. Only individuals with patellar and tibial edema were included in the study group. These MR examinations were then reviewed for associated internal derangements. From March 2007 to June 2013, 1914 MR examinations of the knee were performed. Two hundred seventy-one reports described patellar edema. Seven individuals had edema of both the inferior pole of the patella and the anterior tibial plateau. Three individuals were involved in motor vehicle accidents (MVAs); 4 patients had a history of an axial load or sports-related injury. All 3 patients involved in MVAs had posterior cruciate ligament tears consistent with posterior translation of the tibia. The non-MVA individuals had tears of the ACL with internal derangements similar to other ACL deficient knees, however, with more widespread osseous contusions. Patellotibial contusions are high-energy injuries resulting in cruciate ligament tears. These contusions occur exclusively in patients with ACL tears when individuals with a history of direct impaction to the knee are excluded. Axial loading of the extended knee may be an important mechanism of injury in these individuals.

Comparison of culture media for the recovery of airborne yeast in wineries

The direct air sampling impaction method on agar was evaluated using aerobiocollectors for the recovery of yeasts present in the winery air. Three culture media with different composition and specificity were studied. In addition, a resuscitation phase was included before the culture in the specificity medium [in the case of the Dekkera-Brettanomyces Differential Medium (DBDM) medium]. Sampling was conducted at different times of the year and in different parts of the wineries, which were different in age and design. Both the Chloramphenicol Glucose Agar (CGA) and Agar Lysine AL media recovered yeasts from the air without any prior resuscitation phase. CGA was able to recover a higher number of colony-forming units of yeasts than the other media. Consequently, to estimate the number of yeasts present in winery air, the best choice of medium would be CGA. The AL medium permitted the growth of the greatest range of genera and species. If the aim is to study the diversity of yeasts present in the air, the most suitable medium is AL. Neither CGA nor AL proved suitable for recovering yeasts of the Brettanomyces genus. The DBDM medium was the only one which provided sufficient specificity for their recovery and identification from the air, although their special characteristics made a prior protocol of resuscitation necessary.

Minimally invasive presacral approach for revision of an Axial Lumbar Interbody Fusion rod due to fall-related lumbosacral instability: a case report

IntroductionThe purpose of this study was to describe procedural details of a minimally invasive presacral approach for revision of an L5-S1 Axial Lumbar Interbody Fusion rod.Case presentationA 70-year-old Caucasian man presented to our facility with marked thoracolumbar scoliosis, osteoarthritic changes characterized by high-grade osteophytes, and significant intervertebral disc collapse and calcification. Our patient required crutches during ambulation and reported intractable axial and radicular pain. Multi-level reconstruction of L1-4 was accomplished with extreme lateral interbody fusion, although focal lumbosacral symptoms persisted due to disc space collapse at L5-S1.Lumbosacral interbody distraction and stabilization was achieved four weeks later with the Axial Lumbar Interbody Fusion System (TranS1 Inc., Wilmington, NC, USA) and rod implantation via an axial presacral approach.Despite symptom resolution following this procedure, our patient suffered a fall six weeks postoperatively with direct sacral impaction resulting in symptom recurrence and loss of L5-S1 distraction. Following seven months of unsuccessful conservative care, a revision of the Axial Lumbar Interbody Fusion rod was performed that utilized the same presacral approach and used a larger diameter implant. Minimal adhesions were encountered upon presacral re-entry. A precise operative trajectory to the base of the previously implanted rod was achieved using fluoroscopic guidance. Surgical removal of the implant was successful with minimal bone resection required. A larger diameter Axial Lumbar Interbody Fusion rod was then implanted and joint distraction was re-established. The radicular symptoms resolved following revision surgery and our patient was ambulating without assistance on post-operative day one. No adverse events were reported.ConclusionsThe Axial Lumbar Interbody Fusion distraction rod may be revised and replaced with a larger diameter rod using the same presacral approach.

Computational Fluid Dynamics Study of Airflow and Particle Transport in Third to Sixth Generation Human Respiratory Tract

The computational fluid dynamics (CFD) technique is used to simulate airflow and aerosol-particle deposition in human respiratory tract. The three dimensional respiratory tract is extended from third to six generation bronchus based on Weibel model (1963). The computation is performed for laminar flow condition. Discrete phase modeling (DPM) is used to study the two phase flow. The aerosol-particles of three different diameters 1, 5 and 10 μm are considered to obtain the effect of aerosol-particle size on deposition efficiency. The results of velocity contours, aerosol-particle deposition efficiency and aerosol-particle trapping process are determined at different locations of the respiratory tract. It is obtained that deposition efficiency increases with the increase of aerosol-particle size. It is also found that more are deposited at the bifurcation junctions because of the direct inertial impaction at these locations. Computational results are found useful to correlate the medical and engineering aspects.