Inhalation bioaccessibility of polycyclic aromatic hydrocarbons in heavy PM2.5 pollution days: Implications for public health risk assessment in northern China

Airborne (PM_2.5) with aerodynamic diameter ≤ 2.5 μm was collected from 4 types of cities in northeast China during the heating period. The objectives of this study were to assess the concentrations variation of PM_2.5-bound 12 carcinogenic polycyclic aromatic hydrocarbons (PAH₁₂), to study the influence of simulated lung fluids on bioaccessibility of PAH₁₂ and to estimate the variation of lifetime excess cancer risk to the residents, artificial lysosomal fluid (ALF) and Gamble's solution were used. The number of lifetime excess cancer cases (determined by California Environmental Protection Agency method) as a result of PAH₁₂ exposure (total concentration) was 4.00-430 (provincial central cities), 24.0-261 (energy-mining cities), 17.0-109 (forested city), and 20.0-69.0 (agricultural city) per million people, which relatively corresponded to a 92.2% and 96.2%, 92.6% and 97.3%, 92.2% and 94.2%, and 86.5% and 92.6% decrease after considering bioaccessibility following 24-h of Gamble's solution and ALF extraction, respectively. Phenanthrene (Phe), dibenz[a,h]anthracene (DahA) and benzo[a]pyrene (BaP) were found to be the most bioaccessible types of PAH₁₂ after the Gamble's solution and ALF extraction in the PM_2.5 samples from all the studied cities. Based on the point-estimate approach, short-term predictions of pulmonary toxicity caused by potential inhalation of airborne PM into the pulmonary system might be overestimated if bioaccessibility of PM_2.5-bound PAH₁₂ is not fully evaluated.

Giant nonlinear damping in nanoscale ferromagnets

Magnetic damping is a key metric for emerging technologies based on magnetic nanoparticles, such as spin torque memory and high-resolution biomagnetic imaging. Despite its importance, understanding of magnetic dissipation in nanoscale ferromagnets remains elusive, and the damping is often treated as a phenomenological constant. Here, we report the discovery of a giant frequency-dependent nonlinear damping that strongly alters the response of a nanoscale ferromagnet to spin torque and microwave magnetic field. This damping mechanism originates from three-magnon scattering that is strongly enhanced by geometric confinement of magnons in the nanomagnet. We show that the giant nonlinear damping can invert the effect of spin torque on a nanomagnet, leading to an unexpected current-induced enhancement of damping by an antidamping torque. Our work advances the understanding of magnetic dynamics in nanoscale ferromagnets and spin torque devices.

The impact of urban open space and 'lift-up' building design on building intake fraction and daily pollutant exposure in idealized urban models

Sustainable urban design is an effective way to improve urban ventilation and reduce vehicular pollutant exposure to urban residents. This paper investigated the impacts of urban open space and 'lift-up' building design on vehicular CO (carbon monoxide) exposure in typical three-dimensional (3D) urban canopy layer (UCL) models under neutral atmospheric conditions. The building intake fraction (IF) represents the fraction of total vehicular pollutant emissions inhaled by residents when they stay at home. The building daily CO exposure (E_t) means the extent of human beings' contact with CO within one day indoor at home. Computational fluid dynamics (CFD) simulations integrating with these two concepts were performed to solve turbulent flow and assess vehicular CO exposure to urban residents. CFD technique with the standard k-ε model was successfully validated by wind tunnel data. The initial numerical UCL model consists of 5-row and 5-column (5×5) cubic buildings (building height H=street width W=30m) with four approaching wind directions (θ=0°, 15°, 30°, 45°). In Group I, one of the 25 building models is removed to attain urban open space settings. In Group II, the first floor (Lift-up1), or second floor (Lift-up2), or third floor (Lift-up3) of all buildings is elevated respectively to create wind pathways through buildings. Compared to the initial case, urban open space can slightly or significantly reduce pollutant exposure for urban residents. As θ=30° and 45°, open space settings are more effective to reduce pollutant exposure than θ=0° and 15°.The pollutant dilution near or surrounding open space and in its adjacent downstream regions is usually enhanced. Lift-up1 and Lift-up2 experience much greater pollutant exposure reduction in all wind directions than Lift-up3 and open space. Although further investigations are still required to provide practical guidelines, this study is one of the first attempts for reducing urban pollutant exposure by improving urban design.

[Sinus pericranii in adults: clinical features and therapeutic management (13 cases report)]

Objective: To study the character of sinus pericranii in the adults and enhance the levels of the diagnosis and treatment of sinus pericranii. Methods: The clinical data of 13 adult patients with sinuses pericranii undergoing surgery in Beijing Hospital from 1992 to 2016 were analyzed retrospectively, including clinical manifestations, imaging data, surgical results. Results: Each of the patients presented with a nonpulsatile and soft tissue mass in their heads.Their ages ranged from 18 to 48 years (mean, 26 years). The diagnosis of the sinus pericranii was made by the clinical manifestations combined with CT and/or MRI examinations.The sinus pericranii did not play the main role in the drainage of the cerebral vein blood.All the patients were cured.The follow up time was from 6 months to 20 years with no sinus pericranii recurrence in all the patients. Conclusions: The analysis of the drainage pattern of sinus pericranii was necessary before surgery in order to get a safe and good operation.The curative effect of the surgery on the sinus pericranii in adult was reliable.

[Anatomy and management of superior petrosal vein in microvascular decompression for trigeminal neuralgia]

Objective: To investigate the characteristics of superior petrosal vein (SPV) and its influence on the surgical field in microvascular decompression (MVD) for trigeminal neuralgia (TN), and to analyze the effect of the surgical treatment of SPV on the surgical approach, indication and prognosis. Methods: The clinical data of 280 patients with trigeminal neuralgia between Jan. 2013 and Jun. 2016 were collected, including the trunks and the branches of SPV, intraoperative electrocoagulation status, the surgery outcome and complications. Results: The petrosal vein during the operation was fully preserved in 152 cases (54.29%). The SPV were completely sectioned in 25 cases (8.92%), while some branches of SPV were sectioned in 103 cases (36.79%). We found that SPV have 1 to 3 trunks, accounted for 67 cases (23.90%), 168 cases (60%), and 45 cases (16.10%), while the SPV with 1 to 4 branches accounted for 17 cases (6.07%), 112 cases (40%), 136 cases (48.57%), and 15 cases (5.36%). The SPV was identified as offending vessel in 17 cases (6.07%). One patient with cutoff SPV trunk encountered cerebellar infarction and recovered completely at 2 weeks after MVD by using intravenous medication. Conclusions: MVD is the recommended treatment method for PTN, mostly SPV is unnecessary to be sectioned completely and small branches of SPV could be sacrificed. Very few patients may develop cerebellar infarction or hematoma.

[Microsurgical treatment of apical region by combined orbital pterygoid approach]

OBJECTIVE

To study microsurgical treatment of orbital apical region tumor by combined orbital pterygoid approach.

METHOD

In 21 cases, manifestations and surgical methods were analyzed retrospectively. The surgical approach and procedure were discussed.

RESULTS

All the 21 cases were treated by combined orbital pterygoid approach. The tumors were removed completely in 18 cases, and partially resected in 3. There was no death.

CONCLUSIONS

This kind of mass is difficult to explore by either transorbital or transcranial approach because of its position. Combined orbital pterygoid approach provides better access and exploration. Appropriate surgical approach, hemostasis and gentle microsurgical manipulation are the key to reducing postoperative complications.

[Transoral microsurgical treatment of craniocervical malformation]

OBJECTIVE

To discuss transoral microcervical treatment of 16 patients with craniocervical malformation.

METHODS

Perioperative treatment including antibiotics, tracheotomy, intravenous nutrition was used in 16 patients.

RESULTS

Eight patients had basilar impressions, 3 chronic atlantoaxial dislocation and 2 odontoid fracture, 2 lower clivus chordoma, and 1 granuloma in the ventral part of the medulla oblongata. Three patients received bone graft. Follow-up for 6 - 36 months showed that 14 patients resumed normal life but 1 died.

CONCLUSIONS

Pre-craniocervical malformation can be treated by transoral approach microsurgically. Understanding microanatomy of this approach can reduce postoperative morbidity and complications. Perioperative treatment can prevent incision infection. Prevention of intraoperative CSF leakage must be emphasized.Bone graft can make craniocervical spine stable.

Studies on biosensor to determine diacetyl

We studied the purification of diacetyl reductase, the preparation of a biosensor, and its performance. With diacetyl reductase and reduced coenzyme I (NADH) co-immobilized as working membrane, NAD+/NADH produced in the course of diacetyl reduction was connected with Fe2+/Fe to build a biosensor. The biosensor could be used to determine diacetyl concentration within the range from 0.1 microgram/mL to 0.5 microgram/mL and the response time was less than two minutes, and its performance was stable within 9 days. The experiments showed that typical metal ions and organics in nominal concentration did not affect the performance of the biosensor, meanwhile, the interference of dissolved oxygen on the performance of biosensor and regeneration of coenzyme I (NADH) were solved to some extent.