Reduction of Hysteresis in Hybrid Perovskite Transistors by Solvent-Controlled Growth

The effect of crystallization process speed on the morphology of solution-processed methyl ammonium lead iodide (MAPbI₃) thin films is investigated. Crystallization speed is controlled by varying the number of annealing steps, temperature, and resting time between steps. The resting period allows solvent-controlled growth (SCG) in which crystallization progresses slowly via an intermediate phase—during which solvents slowly evaporate away from the films. SCG results in fewer residues, fewer pinholes, and larger grain sizes. Consequently, thin-film transistors with SCG MAPbI₃ exhibit smaller hysteresis in their current-voltage characteristics than those without, demonstrating the benefits of SCG toward hysteresis-free perovskite devices.     

Cellular and molecular mechanisms in the development of a cleft lip and/or cleft palate; insights from zebrafish (Danio rerio)

Human cleft lip and/or palate (CLP) are immediately recognizable congenital abnormalities of the face. Lip and palate develop from facial primordia through the coordinated activities of ectodermal epithelium and neural crest cells (NCCs) derived from ectomesenchyme tissue. Subtle changes in the regulatory mechanisms of NCC or ectodermal epithelial cells can result in CLP. Genetic and environmental contributions or a combination of both play a significant role in the progression of CLP. Model organisms provide us with a wealth of information in understanding the pathophysiology and genetic etiology of this complex disease. Small teleost, zebrafish (Danio rerio) is one of the popular model in craniofacial developmental biology. The short generation time and large number of optically transparent, easily manipulated embryos increase the value of zebrafish to identify novel candidate genes and gene regulatory networks underlying craniofacial development. In addition, it is widely used to identify the mechanisms of environmental teratogens and in therapeutic drug screening. Here, we discuss the value of zebrafish as a model to understand epithelial and NCC induced ectomesenchymal cell activities during early palate morphogenesis and robustness of the zebrafish in modern research on identifying the genetic and environmental etiological factors of CLP.     

The effect of chin cup therapy on the growth and development of the cranial base and midface

The purpose of this study was to determine how the growth rates of certain cranial base and midfacial points and dimensions were affected by force application to the mandible by the chin cup. Control and treated samples consisting of Japanese girls with skeletal Class III relationships were analyzed. Each sample consisted of lateral cephalometric radiographs taken annually (control group) or semiannually (treated group) from early childhood through adolescence. The control sample was composed of seven persons and the treated sample of ten persons. The subjects of the treated sample were required to wear a chin cup a minimum of 12 hours per day. The total force delivered was 500 g, 250 g per side, and the direction of force was, on average, through the condyle. No other appliances were used. The results of this study indicate that the chin cup causes a closing of the cranial flexure angle N-S-Ba, inhibits posterior growth of the point basion, and imposes a vertical growth tendency on the points nasion and sella. The chin cup significantly inhibits anterior and posterior vertical maxillary growth and growth of upper anterior facial height. Because development of vertical posterior facial height is inhibited more than anterior facial height, a clockwise rotation of the maxilla occurs. The chin cup also causes flaring and a decrease in eruption rate of the maxillary incisors. It has no effect on the eruption rate of the maxillary molars, but accelerates their rate of mesial movement as compared with controls.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of varying the force direction on maxillary orthopedic protraction

The aim of this study was to examine the effect of varying the force direction on maxillary protraction. A total of 20 patients with class III maxillary retrognathism were randomly divided into two groups. Group 1 was comprised of nine patients with a mean age of 8.58 years, and group 2 was composed of 11 patients with a mean age of 8.51 years. Both groups received a cap splint-type rapid palatal expander and the screw was activated twice a day for 10 days. After the expansion procedure the face mask protraction procedure was initiated. In group 1, we applied the force intraorally from the canine region with a forward and downward direction at a 30 degrees angle to the occlusal plane. In group 2, the force was applied extraorally 20 mm above the maxillary occlusal plane. In both groups a unilateral 500 g force was applied and the patients were instructed to wear the face mask for 16 h/d for the first three months and 12 h/d for the next three months. The Wilcoxon sign rank test was used to evaluate the effect of the two different face masks, and a Mann-Whitney U-test was carried out to evaluate the differences between the two groups. The results showed that both force systems were equally effective to protract the maxilla; however, in group I we observed that the maxilla advanced forward with a counter-clockwise rotation. In group 2 we observed an anterior translation of maxilla without rotation. The dental effects of both methods were also different. The maxillary occlusal plane did not rotate in group 1, in contrast to the clockwise rotation in group 2. The maxillary incisors were proclined slightly in group 1, but in contrast they were retroclined and extruded in group 2. In conclusion, the force application from near the center of resistance of the maxilla was an effective method to prevent the unwanted side effects, such as counter-clockwise rotation of the maxilla, in group 1. The group 2 results suggest that this method can be used effectively on patients who present as class III combined with an anterior open bite.     

Appraisal of a modified medial canthal plication for treating laxity of the medial lower eyelid.

PURPOSE: The purpose of this study was to evaluate the efficacy of modified medial canthal tendon plication technique for correcting laxity of the medial end of the lower eyelid. MATERIAL AND METHODS: Eleven patients (9 males and 2 females, 21 eyes), with an age range of 31-80 years, having laxity of the medial end of the lower lid of varying degrees were enrolled in this study. These patients presented with complaints of watering, recurrent redness, photophobia and foreign body sensation. After grading the amount of lower lid laxity, plication was performed. In patients in whom laxity was associated with ectropion, the severity of lower lid ectropion was also graded. In patients with ectropion of Grade II or more, additional procedures for its correction were performed before undertaking plication. The patients were followed up 6 months post-operatively and re-assessed for laxity, recurrence of symptoms and complications of plication. RESULTS: All the lids were evaluated for the amount and extent of laxity of lower lid. Twelve (57%) eyes had Grade I, 9 (43%) had Grade II (and none Grade III) laxity of the lower lid. Twelve eyes had laxity restricted to the medial end and 9 eyes had laxity of the entire length of the lower lid. Some eyes also had an associated ectropion. Among the 21 eyes, 4 eyes (22%) had Grade 1, 11 (61%) had Grade 2, 6 (17%) Grade 3 and none Grade 4 ectropion. In the lids with associated ectropion, additional procedures had been performed. In 1 eye, the medial canthus was anchored to the tendon and this patient had poor apposition of the lower lid to the globe. Hence, in the remaining 20 eyes, the medial canthus was anchored to the orbital periosteum. The mean change in eyelid length was 2.6 mm (measured from medial to lateral canthus) from pre-operative status (33+/-3.4 mm) to the post-operative status (30+/-2.9 mm) this being statistically significant. An overriding of the lower lid was seen in 2 eyes (10%), and a residual gap between the lower lid and globe was noticed in 15 (71%) eyes. Some eyes had uncorrected symptoms including epiphora (3 eyes; 14%), redness (2 eyes; 10%), and photophobia (1 eye; 5%). All were those in which the lateral end was lax. None had a recurrence of foreign body sensation. CONCLUSION: Plication is easy, effective and quick for correcting laxity of the lower lid when restricted predominantly to the medial end. Correct identification of anatomical landmarks and appropriate tension of sutures is vital to achieve proper apposition of the lower lid to the globe.     

Resurgence of therapeutically destitute tuberculosis: amalgamation of old and newer techniques

Most of thoracic surgery developed as a result of efforts to treat tuberculosis (TB). The role of surgical therapy has declined but the role of surgery in TB still remains in situations like diagnostic difficulties, persistent sputum positive state despite therapy and complications and sequel like haemoptysis, destroyed or bronchiectatic lungs or empyema with or without broncho-pleural fistula (BPF). Various procedures have a role according to the indication. Some of the procedures have become obsolete but lobectomy, pneumonectomy, thoracoplasty, decortication and open window thoracostomy continue to be relevant. Recent published series have demonstrated mortality ranging from 0% to 3.1%. Surgery for complications and sequel of pulmonary TB still remain an important intervention for alleviation of human misery.KEYWORDS : Thoracic surgery, tuberculosis (TB), surgery, pneumonectomy, thoracoplasty, decortication, window thoracostomy