Retracted Article: Physics of excitons and their transport in two dimensional transition metal dichalcogenide semiconductors

Two-dimensional (2D) group-VI transition metal dichalcogenide (TMD) semiconductors, such as MoS₂, MoSe₂, WS₂ and others manifest strong light matter coupling and exhibit direct band gaps which lie in the visible and infrared spectral regimes. These properties make them potentially interesting candidates for applications in optics and optoelectronics. The excitons found in these materials are tightly bound and dominate the optical response, even at room temperatures. Large binding energies and unique exciton fine structure make these materials an ideal platform to study exciton behaviors in two-dimensional systems. This review article mainly focuses on studies of mechanisms that control dynamics of excitons in 2D systems – an area where there remains a lack of consensus in spite of extensive research. Firstly, we focus on the kinetics of dark and bright excitons based on a rate equation model and discuss on the role of previous ‘unsuspected’ dark excitons in controlling valley polarization. Intrinsically, dark and bright exciton energy splitting plays a key role in modulating the dynamics. In the second part, we review the excitation energy-dependent possible characteristic relaxation pathways of photoexcited carriers in monolayer and bilayer systems. In the third part, we review the extrinsic factors, in particular the defects that are so prevalent in single layer TMDs, affecting exciton dynamics, transport and non-radiative recombination such as exciton–exciton annihilation. Lastly, the optical response due to pump-induced changes in TMD monolayers have been reviewed using femtosecond pump–probe spectroscopy which facilitates the analysis of underlying physical process just after the excitation.

Two-dimensional (2D) group-VI transition metal dichalcogenide (TMD) semiconductors, such as MoS₂, MoSe₂, WS₂ and others manifest strong light matter coupling and exhibit direct band gaps which lie in the visible and infrared spectral regimes.     

Outcomes following PCI in patients with previous CABG

Background : Limited data is available to guide operators as to the optimal revascularisation strategy in patients with previous CABG representing with angina. Method : Retrospective analysis of 161 patients with prior CABG undergoing PCI in two centres between September 2005 and April 2008. Results : 161 patients (132 male, 68 ± 8years) underwent PCI at 126 ± 65 months after index CABG. Clinical presentation of recurrent ischaemia was stable in 59.7% and as an acute coronary syndrome in 40.3% of patients. Mean follow‐up after PCI was 13.5 ± 4.8 months. About 62.7% of patients underwent native vessel PCI, 32.9% had a graft only PCI, and 4.4% having a combination of both. Drug eluting stents were used in 84.9% of cases. There was one cardiac death and one case of redo CABG during follow‐up. Mean CCS angina class decreased from 2.87 to 0.67 (P < 0.0001) in the follow‐up group. About 13.6 % of all patients had a MACE at follow up. This was higher in the graft PCI group (21.6% vs. 8.9%, P = 0.048). About 12.4% of the total cohort underwent repeat PCI although 30% of these required PCI for a de‐novo lesion. TVR rate was significantly higher in patients undergoing graft PCI than native vessel PCI (15% vs. 4.9%, P = 0.031). Graft PCI was an independent predictor (HR 3.73, 1.27–10.87 [95%CI], P = 0.016) of MACE in these patients. Conclusion : PCI significantly improved angina in these patients with low overall rates of TVR. However TVR rate was significantly higher in patients undergoing graft PCI than those undergoing native vessel PCI. © 2011 Wiley‐Liss, Inc.     

Size Dependent Tolerance of Indian Cat Fish Heteropneustes fossilis (Bloch) to Toxicity of Cadmium and Composted Vegetation

Bulletin of Environmental Contamination and Toxicology - Indian catfish Heteropneustes fossilis (Bloch), commonly known as “Singhi” in India, is an air breathing fish with a slender,...     

Studies on Relative Toxicities of Six Insecticides on Epigeic Earthworm, Perionyx excavatus

The 96 h LC₅₀ values of six insecticides were determined on a non-target epigeic earthworm Perionyx excavatus under laboratory conditions. Cypermethrin was found most toxic to P. excavatus (LC₅₀-0.008 mg/kg), followed by endosulfan (LC₅₀-0.03 mg/kg), carbaryl (LC₅₀-6.07 mg/kg), chlorpyrifos (LC₅₀-7.3 mg/kg), aldicarb (LC₅₀-10.63 mg/kg) and monocrotophos (LC₅₀-13.04 mg/kg). When these LC₅₀ values were compared with their respective recommended agricultural doses, aldicarb and carbaryl appeared more dangerous than other pesticides because of their lower LC₅₀ values than their respective recommended agricultural dose. Mean lethal time to cause 50% mortality at recommended agricultural dose (LT₅₀) also indicated that aldicarb achieved the fastest LT₅₀ (26 h) followed by endosulfan (38 h) and carbaryl (44 h) indicating the danger of these pesticides to P. excavatus.     

Ecotoxicological Assessment of Cobalt Used as Supplement in the Diet of Common Carp <Emphasis Type="Italic">Cyprinus carpio</Emphasis>

Experiments were performed in the laboratory to determine if excess levels of Co used as dietary supplement (0.0, 0.05, 0.10 and 1.0%) to enhance growth of the fish Cyprinus carpio was safe for aquatic organisms. Lethal concentrations of Co for tadpole of toad Bufo melanostictus (96 h LC₅₀, 17.2 mg/L), oligochaet worm Branchiura sowerbyi (96 h LC₅₀, 179 mg/L) and crustacean zooplankton Diaptomus forbesi (96 h LC₅₀, 1.5 mg/L) were compared with the concentration of Co in the medium leached from the unused diets and faeces. The results indicated that the Co leached from diet containing 1.0% Co was ecotoxicologically unsafe for crustacean zooplankton.     

Ecotoxicological effects of jute retting on the survival of two freshwater fish and two invertebrates

Severe deterioration of water quality occurs during jute retting in ponds, canals, floodplain lakes, and other inland water bodies in the rural areas of West Bengal in India. Attempts were made to evaluate changes in the physicochemical parameters of water caused by jute retting, and their impact on the survival of two species of freshwater fish (Labeo rohita and Hypophthalmicthys molitrix) and two species of freshwater invertebrate (Daphnia magna, a Cladocera, and Branchiura sowerbyi, an Oligochaeta). Results showed that jute retting in a pond for 30 days resulted in a sharp increase in the BOD (>1,000 times) and COD (>25 times) of the water, along with a sharp decrease in dissolved oxygen (DO). Free CO₂, total ammonia, and nitrate nitrogen also increased (three to five times) in water as a result of jute retting. Ninety-six-hour static bioassays performed in the laboratory with different dilutions of jute-retting water (JRW) revealed that D. magna and B. sowerbyi were not susceptible to even the raw JRW whereas fingerlings of both species of fish were highly susceptible, L. rohita being more sensitive (96 h LC₅₀ 37.55% JRW) than H. molitrix (96 h LC₅₀ 57.54% JRW). Mortality of fish was significantly correlated with the percentage of JRW.     

Effects of Aniline–An Aromatic Amine to Some Freshwater Organisms

We determined the acute and chronic toxicity of aniline to tilapia (Oreochromis mossambicus), cladoceran crusatcea (Moina micrura) and oligochaete worm (Branchiura sowerbyi) using static bioassay tests. The 96h LC₅₀ values of aniline for O. mossambicus, M. micrura and B. sowerbyi were 69.4, 0.6 and 586mg l^–1 respectively. Tilapia responded to even low concentrations of aniline: the fish lost appetite at aniline concentrations as low as 0.02mg l^–1. A 90 d outdoor bioassay with tilapia showed that 0.02mg l^–1 aniline reduced fish yield, specific growth rate and food conversion efficiency. Reproductive functions of fish were affected by aniline at a concentration of 0.5mg l^–1 and above. Dissolved oxygen, primary productivity and plankton population of the test medium also were significantly reduced at 2.65 and 6.94mg l^–1 aniline.     

Toxicity of Thiocyanate to Fish, Plankton, Worm, and Aquatic Ecosystem

Received: 4 August 1999/Accepted: 16 November 1999     

Ultrasound molecular imaging of arterial thrombi with novel microbubbles modified by cyclic RGD in vitro and in vivo

Despite immense potential, ultrasound molecular imaging (UMI) of arterial thrombi remains very challenging because the high-shear arterial flow limits binding of site-targeted microbubbles to the thrombi. The linear Arg-Gly-Asp (RGD) peptides have been successfully applied to evaluate venous, atrial, and arteriolar thrombi, but have thus far failed in the detection of arterial thrombi. Cyclic RGD (Arg-Gly-Asp-D-Phe-Cys) is a cyclic conformation of linear RGD peptides, which has much higher binding-affinity and selectivity for binding to the glycoprotein (GP) IIb/IIIa receptor than its linear counterpart and thus is likely to be an optimal targeted molecular probe for ultrasound molecular imaging of arterial thrombi. In this study, we sought to assess the feasibility of a novel microbubble conjugated with cyclic RGD (Mb-cyclic RGD) in UMI of arterial thrombi in vitro and in vivo . As expected, Mb-cyclic RGD had greater GP IIb/IIIa-targeted binding capability in all shear stress conditions. In addition, the shear stress at half-maximal detachment of Mb-cyclic RGD was 5.7-fold higher than that of microbubbles with non-specific peptide (Mb-CON) (p<0.05). Mb-cyclic RGD enhanced the echogenicity of the platelet-rich thrombus in vitro whereas Mb-CON did not produce enhancement. In the in vivo setting, optimal signal enhancement of the abdominal aortic thrombus was displayed with Mb-cyclic RGD in all cases. Mean video intensity of the abdominal aortic thrombi with Mb-cyclic RGD was 3.2-fold higher than that with Mb-CON (p<0.05). The novel Mb-cyclic RGD facilitated excellent visualisation of arterial thrombi using UMI and showed great promise for clinical applications.     

Adult right-sided Bochdalec hernia containing perforated colon

Introduction

The literature describes less than a dozen cases of right-sided diaphragmatic hernias. Herein, we present an unusual case of this kind in an adult patient. The hernial contents included the liver, omentum and large bowel.

Aim

This case is reported for its rarity because it was identified in an elderly patient on the right side of the diaphragm with the liver being among the contents of the hernia. The present case is unique as a right-sided Bochdalek hernia containing perforated colon is a rare finding.

Case profile

A 40-year-old male presented to the emergency room with distension of the abdomen and pain of 4 days duration. He was found to be tachycardic and normotensive. The right hemithorax showed decreased expansion as compared to the left and breath sounds were diminished on the right side. A chest X-ray revealed bowel loops in the right hemithorax and air-fluid level in the abdomen suggestive of small bowel obstruction. Computed tomography identified herniation of the right colon and liver through a posterior defect in the right hemidiaphragm. After adequate resuscitation, a laparotomy with a right sided thoracotomy was performed, and the hernia was explored. The patient had an eventful recovery in terms of wound infection. No signs of recurrence were observed during 12 months of follow-up.

Conclusion

Adulthood right-sided Bochdalek hernias are extremely rare. Signs and symptoms can be non-specific and the present case highlights the importance of acquiring a CT scan at the earliest opportunity. This is crucial to the management of these patients as a delay in diagnosis can increase the risk of mortality.