First-principles investigation of the valley and electrical properties of carbon-dopedα-graphyne-like BN sheet

Based on ab initio density functional theory calculations,we demonstrate that two carbon-doped boron nitride analog ofα-graphyne structures,B_(3) C_(2) N_(3)) and BC_(6) N monolayers,are two-dimensional direct wide band gap semiconductors,and there are two inequivalent valleys in the vicinities of the vertices of their hexagonal Brillouin zones.Besides,B_(3)C_(2)N_(3) and BC_(6)N monolayers exhibit relatively high carrier mobilities,and their direct band gap feature is robust against the biaxial strain.More importantly,the energetically most favorable B_(3)C_(2)N_(3) and BC_(6)N bilayers also have direct wide band gaps,and valley polarization could be achieved by optical helicity.Finally,we show that BC_(6) N monolayer might have high efficiency in photo-splitting reactions of water,and a vertical van der Waals heterostructure with a type-Ⅱenergy band alignment could be designed using B_(3)C_(2)N_(3)and BC_(6)N monolayers.All the above-mentioned characteristics make B_(3)C_(2)N_(3) and BC_(6)N monolayers,bilayers,and their heterostructures recommendable candidates for applications in valleytronic devices,metal-free photocatalysts,and photovoltaic cells.

Dermoscopy of perforating lichen nitidus:a case report

To the Editor:Perforating dermatoses is a group of diseases characterized by papulonodular rashes with the elimination of endogenous or exogenous materials through the epidermis.The primary perforating disorders include reactive perforating collagenosis,elastosis perforans serpiginosa,Kyrle disease,perforating folliculitis,and acquired perforating dermatosis.The perforating phenomenon could also be secondary to some other skin disorders,such as calcinosis cutis,granuloma annulare,chromoblastomycosis,lichen planus,lichen striatus,and rarely,lichen nitidus.Herein,we report a case of extensive perforating lichen nitidus in a Chinese patient.

Acute generalized exanthematous pustulosis induced by mycophenolate mofetil:a case complicated with pemphigus foliaceus

To the Editor:Acute generalized exanthematous pustulosis(AGEP)is a rare clinical reaction mainly induced by drugs,characterized by an acute onset of generalized,nonfollicular sterile pustules on erythematous skin with fever and increased neutrophil count,which is usually accompanied by a relatively favorable prognosis.[1]Hereby,we present a special case of AGEP complicated with pemphigus foliaceus(PF).

An Injectable Hydrogel with or without Drugs for Prevention of Epidural Scar Adhesion after Laminectomy in Rats

Epidural scarring occurs inevitably in the defect after spinal laminectomy, and thus how to prevent or reduce it becomes a challenging topic. In the present study, an injectable hydrogel and its dexamethasone （DEX）-loaded hydrogel systems were adopted to prevent epidural scarring in a postlaminectomy rat model. The hydrogel system composed of poly（D,L-lactic acid-co-glycolic acid）-poly（ethylene glycol）-poly（D,L-lactic acid-co-glycolic acid） （PLGA-PEG-PLGA） triblock copolymers was a free-flowing sol at room temperature, and spontaneously turned into a semi-solid gel at body temperature. A lumbar 3 total laminectomy was performed on Sprague Dawley （SD） rats, and the efficacy of the injectable hydrogel with or without drugs in preventing epidural scar formation was evaluated via the gross anatomical observation and histological examination at one month post-surgery. The results demonstrate that the use of hydrogel alone reduced epidural scarring significantly, whereas the efficacy of the DEX-loaded hydrogels presented an irregular dose-dependency of drug and even the inappropriate drug doses resulted in the negative results. Therefore, the present study confirms that the PLGA-PEG- PLGA hydrogel holds potential as a barrier device to decrease peridural scarring, and reveals that the sustained delivery of the steroid hormone DEX to prevent surgery-related adhesions in the laminectomy defect is complex. Moreover, our in vivo studies also remind the researchers to pay attention to the irregular dose-dependency of the hormone drugs.

Thinking process rules extraction for manufacturing process design

To realize the reuse of process design knowledge and improve the efficiency and quality of process design, a method for extracting thinking process rules for process design is proposed. An instance representation model of the process planning reflecting the thinking process of techni- cians is established to achieve an effective representation of the process documents. The related process attributes are extracted from the model to form the related events. The manifold learning algorithm and clustering analysis are used to preprocess the process instance data. A rule extraction mechanism of process design is introduced, which is based on the related events after dimension reduction and clustering, and uses the association rule mining algorithm to realize the similar process information extraction in the same cluster. Through the vectorization description of the related events, the final process design rules are formed. Finally, an example is given to evaluate the method of process design rules extraction.