Direct Writing of Room Temperature Polariton Condensate Lattice.

Realizing lattices of exciton polariton condensates has been of much interest owing to the potential of such systems to realize analogue Hamiltonian simulators and physical computing architectures. Here, we report the realization of a room temperature polariton condensate lattice using a direct-write approach. Polariton condensation is achieved in a microcavity embedded with host-guest Frenkel excitons of an organic dye (rhodamine) in a small-molecule ionic isolation lattice (SMILES). The microcavity is patterned using focused ion beam etching to realize arbitrary lattice geometries, including defect sites on demand. The band structure of the lattice and the emergence of condensation are imaged using momentum-resolved spectroscopy. The introduction of defect sites is shown to lower the condensation threshold and result in the formation of a defect band in the condensation spectrum. The present approach allows us to study periodic, quasiperiodic, and disordered polariton condensate lattices at room temperature using a direct-write approach.

Highly nonlinear dipolar exciton-polaritons in bilayer MoS2.

Realizing nonlinear optical response in the low photon density limit in solid-state systems has been a long-standing challenge. Semiconductor microcavities in the strong coupling regime hosting exciton-polaritons have emerged as attractive candidates in this context. However, the weak interaction between these quasiparticles has been a hurdle in this quest. Dipolar excitons provide an attractive strategy to overcome this limitation but are often hindered by their weak oscillator strength. The interlayer dipolar excitons in naturally occurring homobilayer MoS2 alleviates this issue owing to their formation via hybridization of interlayer charge transfer exciton with intralayer B exciton. Here we demonstrate the formation of dipolar exciton polaritons in bilayer MoS2 resulting in unprecedented nonlinear interaction strengths. A ten-fold increase in nonlinearity is observed for the interlayer dipolar excitons compared to the conventional A excitons. These highly nonlinear dipolar polaritons will likely be a frontrunner in the quest for solid-state quantum nonlinear devices.

Spin-correlated exciton-polaritons in a van der Waals magnet.

Strong coupling between light and elementary excitations is emerging as a powerful tool to engineer the properties of solid-state systems. Spin-correlated excitations that couple strongly to optical cavities promise control over collective quantum phenomena such as magnetic phase transitions, but their suitable electronic resonances are yet to be found. Here, we report strong light-matter coupling in NiPS3, a van der Waals antiferromagnet with highly correlated electronic degrees of freedom. A previously unobserved class of polaritonic quasiparticles emerges from the strong coupling between its spin-correlated excitons and the photons inside a microcavity. Detailed spectroscopic analysis in conjunction with a microscopic theory provides unique insights into the origin and interactions of these exotic magnetically coupled excitations. Our work introduces van der Waals magnets to the field of strong light-matter physics and provides a path towards the design and control of correlated electron systems via cavity quantum electrodynamics.

Nontrivial quantum oscillation geometric phase shift in a trivial band.

Quantum oscillations provide a notable visualization of the Fermi surface of metals, including associated geometrical phases such as Berry's phase, that play a central role in topological quantum materials. Here we report the existence of a new quantum oscillation phase shift in a multiband system. In particular, we study the ABA-trilayer graphene, the band structure of which is composed of a weakly gapped linear Dirac band, nested within a quadratic band. We observe that Shubnikov-de Haas (SdH) oscillations of the quadratic band are shifted by a phase that sharply departs from the expected 2π Berry's phase and is inherited from the nontrivial Berry's phase of the linear band. We find this arises due to an unusual filling enforced constraint between the quadratic band and linear band Fermi surfaces. Our work indicates how additional bands can be exploited to tease out the effect of often subtle quantum mechanical geometric phases.

Landau Level Diagram and the Continuous Rotational Symmetry Breaking in Trilayer Graphene.

The sequence of the zeroth Landau levels (LLs) between filling factors ν=-6 to 6 in ABA-stacked trilayer graphene (TLG) is unknown because it depends sensitively on the nonuniform charge distribution on the three layers of ABA-stacked TLG. Using the sensitivity of quantum Hall data on the electric field and magnetic field, in an ultraclean ABA-stacked TLG sample, we quantitatively estimate the nonuniformity of the electric field and determine the sequence of the zeroth LLs. We also observe anticrossings between some LLs differing by 3 in LL index, which result from the breaking of the continuous rotational to C_{3} symmetry by the trigonal warping.

Evidences for Inclusion and Encapsulation of an Ionic liquid with ß-CD and 18-C-6 in Aqueous Environments by Physicochemical Investigation.

The interface between pyrrolidinium-based ionic liquid, i.e., 1-ethyl-1-methylpyrrolidinium bromide, with ß-cyclodextrin and 18-crown-6 solution have been compared and explored by means of density, viscosity, refractive index, electrical conductance and surface tension, FTIR, 1H nuclear magnetic resonance, 2D ROESY NMR, and high resolution mass spectroscopy studies. Limiting apparent molar volumes (ϕV0), experimental slopes (SV*) interpreted in terms of inclusion and interaction (ion-solvent, ion-ion). Establishment of binding affinity were discussed in molecular terms supported this inclusion complexation and encapsulation interaction process. The result shows that the stability of the resulting complexes of ß-cyclodextrin:[EMPyrr]+ and 18-crown-6:[EMPyrr]+ is based on the geometrical and spectrometric data. Host guest chemistry of the five-membered nitrogen containing cation with two different macro cyclic hosts is supported by studying NMR. HRMS has been used to support the complexation process with the proper stoichiometry ratio. The solid complex formations were established by Fourier transform infrared study.

Strong electronic interaction and multiple quantum Hall ferromagnetic phases in trilayer graphene.

Quantum Hall effect provides a simple way to study the competition between single particle physics and electronic interaction. However, electronic interaction becomes important only in very clean graphene samples and so far the trilayer graphene experiments are understood within non-interacting electron picture. Here, we report evidence of strong electronic interactions and quantum Hall ferromagnetism seen in Bernal-stacked trilayer graphene. Due to high mobility ∼500,000 cm2 V-1 s-1 in our device compared to previous studies, we find all symmetry broken states and that Landau-level gaps are enhanced by interactions; an aspect explained by our self-consistent Hartree-Fock calculations. Moreover, we observe hysteresis as a function of filling factor and spikes in the longitudinal resistance which, together, signal the formation of quantum Hall ferromagnetic states at low magnetic field.

Genito-urinary tuberculosis in 67 cases: experience from a tertiary core centre in India.

Tuberculosis is very much prevalent in developing countries like India. Genito-urinary tuberculosis usually occurs after 5 to 15 years of the primary lung infection. After lymph node involvement,it is the second common form of extrapulmonary tuberculosis. In this retrospective study, case records of 67 patients diagnosed with genito-urinary tuberculosis in our institute were thoroughly reviewed regarding age, sex, the urogenital organ involved by tuberculosis,mode of diagnosis,and treatment given to the patients. Median age of the patients was 38.5 years, males were more commonly involved than females, kidney was the most common organ involved by tuberculosis followed by ureter and urinary bladder.HIV infection was present in a single patient who had developed tuberculous perinephric abscess. Most common mode of diagnosis was by histopathological examination of the organ involved. Hydronephrosis of the involved kidney with echogenic debris in the dilated pelvicalyceal system on ultrasonography and non-visualised kidney on intravenous urogram was the most common findings on imaging studies who underwent nephrectomy. One patient was seen with tuberculosis of the glans penis which is not much common. Surgical intervention was ablative in nature in most of the cases in the form of nephrectomy. Early diagnosis is important and can prevent the anatomical defor- mity and loss of function of the involved organ.

Xanthogranulomatous pyelonephritis: critical analysis of 18 cases from a rural tertiary care centre of India.

Xanthogranulomatous pyelonephritis is an uncommon disorder of the kidney that is characterised by chronic inflammation and extensive destruction of the involved kidney usually associated with renal calculus and obstruction. It commonly involves the middle aged people with an increased incidence among females and diabetic population. Confirmed diagnosis can be done only after histopathological examination of the diseased nephrectomy specimen. So early suspicion and timely intervention is important to reduce the morbidity. In this retrospective study, we analysed the case records of all patients diagnosed with xanthogranulomatous pyelonephritis in our institute over a period of 11 years. A total 18 patients were treated and diagnosed with xanthogranulomatous pyelonephritis from January 2002 to December 2012. Among them 13 were female and 5 male. Most common clinical presentation was flank pain, fever, dysuria and weight loss. Left kidney was affected in 15 cases and right kidney in 3 cases. All patients were having urinary calculus causing obstruction to the pelvicalyceal system of the kidney. Only 2 patients were diabetic. Urine culture was sterile in all patients. All patients were treated with antibiotics, other supportive measures pre-operatively and ultimate nephrectomy having good recovery. Early suspicion and prompt treatment is necessary in minimising morbidity and mortality from the condition.

Contrast induced nephropathy: our experience.

Even in the light of newer and less nephrotoxic contrast media solutions, their increased use during standard and new radiological procedures has resulted in the growing incidence of contrast-induced nephropathy, an iatrogenic disorder caused by exposure to contrast media. This retrospective study was conducted among the patients admitted in North Bengal Medical College from January 2007 to December 2010 with significant rise in serum creatinine level within 48 to 72 hours of systemic administration of contrast media. The study sample constituted 14 patients with mean age being 45.2 years. Among them, 10 patients (71.4%) required haemodialysis. One patient (7.1%) expired after receiving three sessions of haemodialysis. Three patients (21.4%) became dependent on haemodialysis. Once developed, contrast induced nephropathy is associated with high morbidity, long hospital-stay and patient becomes dependent on haemodialysis. Till now, no available current treatment can reverse or ameliorate the condition once it develops. Some precautionary measures taken in the high risk patients before administration of contrast medium is essential to reduce the incidence.

Analysis of 88 nephrectomies in a rural tertiary care center of India.

Nephrectomy is not an uncommon surgery in day-to-day practice of urology. Trauma is the most common cause of emergency nephrectomy. On the other hand, elective nephrectomy is done for both benign and malignant diseases of the kidney. This study has been performed to know the different causes of nephrectomy in a rural, tertiary care center of India. In our series, we have studied all the elective nephrectomies done in our hospital during a period of eight years. We have analyzed 88 cases of nephrectomies regarding their age, sex, laterality of disease, and histopathologic report of the nephrectomy specimens. Out of 88 cases, 61 were males and 27 were females. In our series, 62.5% cases of nephrectomies were done for benign causes and 37.5% cases for malignant causes. Among the benign causes, neglected pelviureteric junction obstruction was the leading cause, followed by calculus disease resulting in obstruction. On the other hand, renal cell carcinoma was the most common malignant pathology requiring nephrectomy.

Foreign bodies in urinary bladders.

We studied the patients admitted in our hospital with intravesical foreign bodies from February 2007 to January 2009 regarding their clinical presentation, nature of the foreign bodies, and methods used to remove them. The patients with intravesical foreign bodies were investigated and underwent cystoscopy for direct visualization of the foreign body and an attempt to remove it through the cystoscope. If cystoscopic removal failed, then suprapubic cystostomy was done to remove it. Nine patients (six males and three females, with a mean age of 24.5 years) with intra-vesical foreign bodies were admitted during the study period. In all the female patients and one male patient, foreign bodies were introduced inside the bladder by the patients themselves. In four cases, the foreign bodies were iatrogenic in nature, and in one case, it migrated accidentally through the urethra. In conclusion, intravesical foreign bodies are not very uncommon. Self-introduced and iatrogenic foreign bodies into the bladder are more common than accidental migration through the urethra. Cystoscopic removal is successful in most of the cases. If cystoscopic removal is not possible, then suprapubic cystostomy is required to accomplish this task.

Dorsal onlay buccal mucosal graft urethroplasty in long anterior urethral stricture.

OBJECTIVE: To assess the success of buccal mucosal graft (BMG) urethroplasty by the dorsal onlay technique in long anterior urethral stricture (> 2 cm long) through the midline perineal incision. MATERIALS AND METHODS: From January 1998 to December 2003, 43 patients with long anterior urethral strictures were managed by dorsal onlay BMG urethroplasty. After voiding trial, they were followed up at 3 months with uroflowmetry, retrograde urethrogram (RGU) and American Urological Association symptoms score (AUA symptoms scores). Successful outcome was defined as normal voiding with a maximum one attempt of visual internal urethrotomy (VIU) after catheter removal. Patients were further followed-up with uroflowmetry at 3 months interval and RGU every 6 months interval. RESULTS: Mean stricture length was 4.8 cm (range 3 to 9 cm) and mean follow up was 48 months (range 12 to 84 months). Only five patients were found to develop stricture at anastomotic site, during follow-up. Two of them voided normally after single attempt of VIU. Other three patients (6.9%) required further open surgery or repeat VIU during follow up and were considered as failure. CONCLUSION: Dorsal onlay BMG urethroplasty is a simple technique with good surgical outcome.

Dorsal onlay buccal mucosal graft urethroplasty in long anterior urethral stricture

OBJECTIVE: To assess the success of buccal mucosal graft (BMG) urethroplasty by the dorsal onlay technique in long anterior urethral stricture (> 2 cm long) through the midline perineal incision. MATERIALS AND METHODS: From January 1998 to December 2003, 43 patients with long anterior urethral strictures were managed by dorsal onlay BMG urethroplasty. After voiding trial, they were followed up at 3 months with uroflowmetry, retrograde urethrogram (RGU) and American Urological Association symptoms score (AUA symptoms scores). Successful outcome was defined as normal voiding with a maximum one attempt of VIU after catheter removal. Patients were further followed-up with uroflowmetry at 3 months interval and RGU every 6 months interval. RESULTS: Mean stricture length was 4.8 cm (range 3 to 9 cm) and mean follow up was 48 months (range 12 to 84 months). Only five patients were found to develop stricture at anastomotic site, during follow-up. Two of them voided normally after single attempt of VIU. Other three patients (6.9 percent) required further open surgery or repeat VIU during follow up and were considered as failure. CONCLUSION: Dorsal onlay BMG urethroplasty is a simple technique with good surgical outcome.