Note: Measuring capacitance and inductance of a helical resonator and improving its quality factor by mutual inductance alteration

Narrow bandwidth and high voltage radio frequency (RF) is an essential requirement for stable confinement of ions within a RF trap and helical resonators are commonly used for that purpose. Effective capacitance and inductance of a helical resonator are estimated by measuring resonant frequencies for different external loads. Load capacitance of an ion trap can be estimated from this method and a resonator can be constructed for desired resonant frequency. We demonstrate a very simple method to achieve higher Q-factor of a resonator by optimizing mutual separation between the primary antenna and helical coil. We also formulate a set of analytical equations for calculating overall inductance, resistance, and Q-factor of a loaded helical resonator.

Coumarin-based supramolecular gelator: a case of selective detection of F− and HP2O73−

Coumarin-based small molecular gelator 1 forms stable, fluorescent gel from CHCl₃–petroleum ether (1 : 1, v/v). The gel is selectively disintegrated in the presence of F⁻ and hydrogen pyrophosphate.

Naphthalene linked pyridyl urea as a supramolecular gelator: a new insight into naked eye detection of I−in the gel state with semiconducting behaviour

The gelation and anion responsive behavior of some 3-aminopyridinium-based molecules1–5have been examined. Compound2shows naked eye detection of I⁻in the gel state.

Progress of 3-aminopyridinium-based synthetic receptors in anion recognition

This review describes the overall development on synthetic receptors built on the pyridinium motif with different functionalities at the 3-position in anion recognition.

Supported liquid membrane transport studies on Am(III), Pu(IV), U(VI) and Sr(II) using irradiated TODGA

Transport behaviour of actinides viz. Am(3+), Pu(4+) and UO(2)(2+) was investigated from nitric acid feed conditions using PTFE (polytetrafluoroethylene) flat sheet supported liquid membranes (SLM) containing an irradiated solvent system comprising of N,N,N',N'-tetra-n-octyldiglycolamide (TODGA) as the carrier extractant and N,N-di-n-hexyloctanamide (DHOA) as the phase modifier. The present studies were carried out in order to understand the effect of irradiation on the long term reusability of the SLM and the decontamination behaviour in the absorbed dose range of 0-100 MRad. The studies using irradiated carrier included those with irradiated TODGA without any phase modifier and with 0.1M as well as 0.5M DHOA as the phase modifier. Transport behaviour of all the metal ions were found to be seriously affected with increasing radiation dose which was reflected in the decreasing percentage transport (%T) as well as permeability co-efficient (P) values. Though Sr(II) transport was quite significant with all the three unirradiated solvent systems, it was surprisingly low (<5%) when solvents exposed to 100 MRad dose were used in the SLM. Separation factors (S.F.) of the actinides over Sr(II) were calculated and were found to increase at higher radiation doses suggesting possibility of getting better decontamination on prolonged use of the supported liquid membrane system.

Facilitated transport of Pd(II) through a supported liquid membrane (SLM) containing N,N,N',N'-tetra-(2-ethylhexyl) thiodiglycolamide T(2EH)TDGA: a novel carrier

A novel carrier, N,N,N',N'-tetra-(2-ethylhexyl) thiodiglycolamide, T(2EH)TDGA has been studied for transport of Pd(II) from nitric acid medium across a supported liquid membrane (SLM). Pd(II) was found to be almost quantitatively transported (≈ 99.9%) within 2h from 3.0M HNO(3) medium using 0.05 M T(2EH)TDGA in n-dodecane as carrier and 0.01 M thiourea in 0.2M HNO(3) as strippant. Pd(II) transport was also studied against various parameters like feed acidity, carrier concentration, membrane pore size, etc. Palladium transport was found to be diffusion controlled and the diffusion co-efficient value was found to be 3.56 × 10(-5)cm(2)/s. Selectivity of T(2EH)TDGA for palladium over other fission products was found to be quite high, with the separation factors for Pd, with respect to different fission products being >10(3). With respect to leaching out of carrier from the membrane support, the membrane was found to be stable for six consecutive cycles. Thus, T(2EH)TDGA can be used as an efficient carrier of Pd(II) from nitric acid medium.

Facilitated transport of uranium(VI) across supported liquid membranes containing T2EHDGA as the carrier extractant

Facilitated transport of uranyl ion from nitric acid feed solutions was investigated across PTFE supported liquid membranes using N,N,N',N'-tetra-2-ethylhexyl-3-pentane-diamide (T2EHDGA) in n-dodecane as the carrier extractant containing 30% iso-decanol as the phase modifier. Solvent extraction studies indicated extraction of species of the type, UO(2)(NO(3))(2)·T2EHDGA. The distribution coefficients increased in the presence of NaNO(3) as compared to equivalent concentration of HNO(3) which was exactly the opposite of what was reported for Am(III)-TODGA extraction system. Supported liquid membrane studies indicated about 11h were required for quantitative transport of U(VI) from a feed of 3M HNO(3) using 0.2M T2EHDGA in n-dodecane containing 30% iso-decanol as the carrier extractant. Effect of various parameters such as feed acidity, T2EHDGA concentration, and nature of the strippant on the transport rate was investigated. The transport was found to be diffusion controlled in the membrane phase and the permeability coefficient was calculated to be (3.20 ± 0.13)× 10(-4)cm/s for the feed composition of 3M HNO(3), receiver phase composition of 0.01 M HNO(3) and membrane carrier phase of 0.2M T2EHDGA in n-dodecane containing 30% iso-decanol. The present results may be useful for the separation of U from lean solutions or radioactive wastes considered hazardous due to the presence of alpha-particle emitting radionuclides.

Near-infrared photoabsorption by C60 dianions in a storage ring

We present a detailed study of the electronic structure and the stability of C(60) dianions in the gas phase. Monoanions were extracted from a plasma source and converted to dianions by electron transfer in a Na vapor cell. The dianions were then stored in an electrostatic ring, and their near-infrared absorption spectrum was measured by observation of laser induced electron detachment. From the time dependence of the detachment after photon absorption, we conclude that the reaction has contributions from both direct electron tunneling to the continuum and vibrationally assisted tunneling after internal conversion. This implies that the height of the Coulomb barrier confining the attached electrons is at least approximately 1.5 eV. For C(60)(2-) ions in solution electron spin resonance measurements have indicated a singlet ground state, and from the similarity of the absorption spectra we conclude that also the ground state of isolated C(60)(2-) ions is singlet. The observed spectrum corresponds to an electronic transition from a t(1u) lowest unoccupied molecular orbital (LUMO) of C(60) to the t(1g) LUMO+1 level. The electronic levels of the dianion are split due to Jahn-Teller coupling to quadrupole deformations of the molecule, and a main absorption band at 10,723 cm(-1) corresponds to a transition between the Jahn-Teller ground states. Also transitions from pseudorotational states with 200 cm(-1) and (probably) 420 cm(-1) excitation are observed. We argue that a very broad absorption band from about 11,500 cm(-1) to 13,500 cm(-1) consists of transitions to so-called cone states, which are Jahn-Teller states on a higher potential-energy surface, stabilized by a pseudorotational angular momentum barrier. A previously observed, high-lying absorption band for C(60)(-) may also be a transition to a cone state.

Bilateral fibular hemimelia with recto-vestibular fistula associated with amniotic bands

Fibular Hemimelia is a rare congenital disorder of deficiency to complete absence of fibula. It has been associated with post axial skeletal anomalies like shortening of femur, absence of lateral rays of foot and syndactyle, polydactyle etc. We report this case because of associated amniotic constriction bands over both the forearm, suggesting amniotic bands may be one of the causal factors of Fibular Hemimelia due to insult to the growing limb bud.

Ataxica telengiectasia (Louis-Bar syndrome)

A case of ataxia telengiectasia in a 7-year-old girl with symptoms for last 3 years has been reported in detail. The necessary literature has been reviewed with proper references.

Hypertension in the young in eastern India

Three hundred and forty-one young hypertensives in the age group of 18-30 years were evaluated over a 7-year period. Essential hypertension constituted the single largest group (35.8%). Renal pathology was the most common cause of secondary hypertension (26.4%). Congenital coarctation of the aorta and endocrine causes accounted for 14.1 percent and 3.2 percent cases of secondary hypertension, respectively. A strikingly high incidence of nonspecific aortoarteritis (20.1%) was a distinguishing feature amongst secondary causes. Aortoarteritis was the commonest cause of renal artery stenosis. Renal angioplasty was performed in 11 patients with refractory hypertension. Forty percent of the patients achieved post-angioplasty control of blood pressure without drugs; in 25 percent, the blood pressure became easier to control. Restenosis was detected in 4 cases over 18-24 months of follow-up.

Pacing in children and adolescents

Sixty patients aged 5-16 years underwent implantation of permanent pacemaker and were followed up for 3-11 years. All these patients presented with syncope or symptomatic bradyarrhythmias; two also had congestive cardiac failure in addition, which was ameliorated by pacemaker implantation. A majority of the patients (48) had congenital complete heart block. 8 patients presented with sick sinus syndrome; 4 patients presented with post operative chronic complete heart block. Transvenous endocardial electrode was used in 54 cases and epicardial pacing was done in 6 cases. A majority (55) of the patients received VVI pacemakers; AV sequential pacemakers were implanted in 5 cases. On follow up, the children returned to normal activity and their psychological well being was striking. Reoperation had to be done in 35 cases, a majority being due to over stretching of electrodes (15) and battery exhaustion (12). Two patients died, one due to bacterial endocarditis and the other succumbed to sudden death during vigorous physical activity. Major problems of pacing in children are that veins are often too thin and delicate for electrode insertion, and of the child's growth that stretches the lead system. The problems of pulse generator size and longevity have been partly overcome by introduction of newer models that are small and programmable.

Cardiac involvement in non-specific aorto-arteritis

Cardiac involvement in 75 cases (mean age 21.1 +/- 6 years) with non-specific aorto-arteritis was studied. Detailed clinical examination, echocardiography and cardiac catheterization, including angiography, were done in all the cases, as was coronary angiography. Features of cardiac failure like sinus tachycardia, cardiomegaly, left ventricular third heart sound gallop and pulmonary congestion were detected in 27 cases with reduction of left ventricular ejection fraction (25-48%). Systemic hypertension was seen in 60 cases. Central aortic pressure, left ventricular systolic pressure and left ventricular end-diastolic pressure were increased in 66 cases. Pulmonary hypertension and increased pulmonary vascular resistance were detected in 6 cases. Aortic and mitral regurgitation were seen in 15 and 12 cases, respectively. Three patients had features of dilated cardiomyopathy such as generalized cardiomegaly, systemic and pulmonary congestion but without any cardiac murmurs and with normal central aortic pressure. The coronary angiogram revealed obstruction of the left anterior descending artery in 3 cases and right coronary artery obstruction in another 3 cases. Histopathological studies revealed non-specific inflammatory changes with fibrosis in cardiac musculature and the great vessels.

Low dose amiodarone in refractory tachyarrhythmias

Fifty patients with drug resistant tachyarrhythmias were treated with amiodarone for 6-22 months; 16 for recurrent ventricular tachycardia (VT), 2 for VT followed by ventricular fibrillation (VF), 14 for complex ventricular ectopics, and 18 for supraventricular tachyarrhythmias (SVT). Amiodarone was administered in a dose much lower than that used in western trials. The actual incidence of successful amiodarone therapy was 81.2% at 22 months for patients with VT. Among the patients with SVT, 88.6% patients were successfully treated for 22 months (range 3-22 months). Amiodarone toxicity appeared in 22 of 50 patients (44%) treated for more than 12 weeks. Withdrawal of therapy was required in 4 patients. Despite the lower dose, clinical efficacy and onset of action were comparable to the western experience.

Cardiac changes implicated in chronic heart block

Fifteen cases of chronic heart block were studied. Eight of them could be designated as idiopathic or primary heart block; the others were associated with hypertension, diabetes and ischaemic heart disease, either singly or in various combinations. In six cases, the whole heart was available for histopathological study of the conduction system. In the other 9 cases, only a portion of the heart muscle was available for examination. A V nodal fibrosis extending upto the proximal bundle of His was seen in all the six whole heart autopsy materials. Fibrosis of the adjacent myocardium was seen in five cases. In three cases, conducting system fibrosis was associated with atherosclerotic (1 case) or diabetic changes (3 cases) of the intramural vessels. In the 9 partial autopsy studies, myocardial fibrosis was seen in two cases, diabetic microangiopathy in one and atherosclerotic changes in two including an old thrombus in one. Thus, diabetic microangiopathy was seen in total four cases. These changes may be responsible for the cardiomegaly and cardiac failure associated with conduction defects observed in diabetes. In the idiopathic group also, heart block could be considered as a significant facet of a primary myocardial degenerative process.

Aortic dissection in a non-marfanoid child

A nine year old girl presented with chest pain and dyspnoea of sudden onset. She had no marfanoid features, with a normal slit lamp examination and a normal aortic valve on echocardiography. The diagnosis of dissecting aneurysm of the ascending aorta involving the aortic valve cusps, the right coronary artery and the pericardium was later established with the help of ECG, pericardiocentesis, echocardiography and aortography.

An unusual extension of pericardial effusion in a case of pulmonary adenocarcinoma

A case of pericardial metastasis from adenocarcinoma of lung was having a separate paratracheal bulge at left border of aorta mimicking a tumour. This was a very uncommon extension of pericardial effusion. Interestingly this mediastinal bulge on left border of aorta disappeared completely immediately after pericardio-centesis. The rarity of chest roentgenographic findings prompted us to report this case.