Investigating ripple pattern formation and damage profiles in Si and Ge induced by 100 keV Ar+ ion beam: a comparative study.

Desired modifications of surfaces at the nanoscale may be achieved using energetic ion beams. In the present work, a complete study of self-assembled ripple pattern fabrication on Si and Ge by 100 keV Ar+ ion beam bombardment is discussed. The irradiation was performed in the ion fluence range of ≈3 × 1017 to 9 × 1017 ions/cm2 and at an incident angle of θ ≈ 60° with respect to the surface normal. The investigation focuses on topographical studies of pattern formation using atomic force microscopy, and induced damage profiles inside Si and Ge by Rutherford backscattering spectrometry and transmission electron microscopy. The ripple wavelength was found to scale with ion fluence, and energetic ions created more defects inside Si as compared to that of Ge. Although earlier reports suggested that Ge is resistant to structural changes upon Ar+ ion irradiation, in the present case, a ripple pattern is observed on both Si and Ge. The irradiated Si and Ge targets clearly show visible damage peaks between channel numbers (1000-1100) for Si and (1500-1600) for Ge. The clustering of defects leads to a subsequent increase of the damage peak in irradiated samples (for an ion fluence of ≈9 × 1017 ions/cm2) compared to that in unirradiated samples.

Monstera deliciosa mediated single step biosynthesis of gold nanoparticles by bottom-up approach and its non-antimicrobial properties.

In this study, we have stated the green biosynthesis of gold nanoparticles (AuNPs) by utilizing the extract of Monstera deliciosa leaves (MDL) as a reducing agent. Biosynthesized flat, thin, and single-crystalline gold nanotriangles obtained through centrifugation are then analyzed by different characterization techniques. The UV - visible absorption spectra of AuNPs exhibited maxima bands in the range of 500-590 nm, indicating a characteristic of AuNPs. XRD analysis revealed the formation of the (111)-oriented face-centered cubic (FCC) phase of AuNPs. ATR-IR spectra showed signatures of stretching vibrations of O-H, C-H, C=C, C=O, C-O, and C-N, accompanied by CH3 rocking vibrations present in functional groups of biomolecules. FESEM images confirmed spherical nanoparticles with an average diameter in the range of 53-66 nm and predominantly triangular morphology of synthesized AuNPs within the size range of 420-800 nm. NMR, GC-MS, and HR-MS studies showed the presence of different biomolecules, including phenols, flavonoids, and antioxidants in MDL extracts, which play a crucial role of both, reducing as well as stabilizing and capping agents to form stable AuNPs by a bottom-up approach. They were then investigated for their antibacterial assay against Gram-positive (S. aureus, B. subtilis) and Gram-negative (E. coli, P. aeruginosa) microorganisms, along with testing of antifungal potential against various fungi (Penicillium sp., Aspergillus flavus, Fusarium oxysporum, Rhizoctonia solani) using the well diffusion method. Here, biosynthesized AuNPs showed non-antimicrobial properties against all four used bacteria and fungi, showing their suitability as a contender for biomedical applications in drug delivery ascribed to their inert and biocompatible nature. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03898-0.

Study of Ion Velocity Effect on the Band Gap of CVD-Grown Few-Layer MoS2.

The present work reports on a simple chemical vapor deposition (CVD) technique that employs alkali halide (NaCl) to synthesize high-quality few-layer MoS2 by reducing growth temperature from 850 to 650 °C, and its ion irradiation study for band gap modification. The Raman peak position difference of A1g to E12g of ≈24.5 cm-1 for the synthesized MoS2 corresponds to a few layers (<5 monolayers) of MoS2 on the substrate, as also confirmed by atomic force microscopy (AFM). The optical image shows the continuous distribution of flakes throughout the substrate and the average area of flakes ≈0.2 µm2 as confirmed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. Swift heavy-ion (SHI) irradiation at 60, 100, and 150 MeV ion energies of 1 × 1012 ions/cm2 ion fluence have been used to modify the band gap in few-layer MoS2. The ions with two different energies are chosen at two sides of the Bragg peak of energy loss curve in such a way as to have the same value of electronic energy loss (Se) but different ion energies to examine the velocity effect for the ion-induced modification. The absorbance peaks for 60 and 150 MeV irradiated samples show the same effect in the band gap modification.

An investigation of luminescence properties of CaF2: Dy nanophosphor irradiated with gamma rays and low energy proton beams.

This paper reports the luminescence properties of nanocrystalline calcium fluoride doped with dysprosium (CaF2: Dy). The nanophosphor has been synthesized by the chemical co-precipitation technique and the dopant concentration has been optimized at 0.3 mol% using thermoluminescence (TL) intensity emitted post 50Gy gamma dose irradiation of samples doped with different dopant concentrations. X-ray diffraction shows the formation of crystalline particles with an average size of 49.233 nm. Photoluminescence (PL) emission spectrum shows the characteristic peaks at 455 nm, 482 nm, 573 nm corresponding to 4I15/2 to 6H15/2, 4F9/2 to 6H15/2 and 4F9/2 to 6H13/2 Dy3+ transitions respectively. PL excitation spectrum shows a peak at 327 nm which corresponds to the Dy3+ transition of 6H15/2 to 4L19/2. Gamma (of 1.25 MeV) and low energy proton beam (of 30 keV) irradiated nanophosphor shows a variation in TL glow curve structure and peak position with an increase in radiation dose/fluence. However, the nanophosphor shows a wide linear dose response for 60Co gamma radiation in the range 10 Gy - 1.5 kGy and for low energy proton beam in the fluence range of 1012-1014 ions/cm2. Srim 2013 has been used to calculate the ion beam parameters including the range of protons in CaF2: Dy 0.3 mol%. The nanophosphor CaF2: Dy could be further investigated as a potential dosimeter for gamma rays and proton beam by studying its TL properties for different energies of these radiations.

Effect of Vitamin D Supplementation on CD4 Count in HIV-Infected Children and Adolescents in North India: A Non-Randomized Comparative Study.

BACKGROUND: HIV infection is still a serious public health issue globally. Suboptimal vitamin D status is highly prevalent in HIV-infected children and adolescents throughout the world. OBJECTIVES: To evaluate the outcome of vitamin D supplementation on CD4 count in HIV-infected children and adolescents with suboptimal vitamin D status. METHODS: Vitamin D level of HIV-infected children and adolescents were measured at enrolment. Suboptimal vitamin D level was defined as 25(OH)D < 30 ng/ml. Vitamin D insufficiency and deficiency were defined as 21-29 and <20 ng/ml, respectively. Children with suboptimal vitamin D levels were supplemented with vitamin D. RESULTS: This was a single-centre, non-randomized comparative study enrolling 50 eligible participants. There were 20 patients who were vitamin D sufficient, 7 were vitamin D insufficient and 23 were found to be vitamin D deficient at enrolment. However, after supplementation, the status of sufficient remained same and 7 insufficient become sufficient, whereas in 23 deficient, 18 (78.3%) become sufficient and 5 (21.7%) become insufficient and this change was found statistically significant among the groups (χ2 = 6.52, p = 0.038). There was a significant improvement of CD4 count from baseline to 4 months in deficient group on vitamin D supplementation (p value < 0.001; 1.2-fold rise). No significant change was seen in vitamin D insufficient (p value = 0.791) and sufficient groups (p value = 0.168). CONCLUSION: Vitamin D should be supplemented in HIV-infected children on ART with low CD4 counts.

Investigations of thermoluminescence characteristics of CaSiO3:Yb phosphor irradiated with gamma rays and carbon ion beam.

In the present work, the thermoluminescence (TL) properties of Yb doped CaSiO3 phosphor exposed to gamma rays and carbon (C) ion beam have been reported. The phosphor has been synthesized using solid-state reaction method. The formation and surface morphology of the phosphor have been studied using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) respectively. The optical band gap of the phosphor is determined using UV-Visible spectroscopy. TL properties on Yb doped CaSiO3 phosphor irradiated with carbon ion beam has been reported first time. Different TL properties like TL glow curve, dose response, fading etc. have been investigated in detail. The TL glow curve of CaSiO3:Yb phosphor consists of two prominent glow peaks. Under gamma irradiation, the main dosimetric peak is centered at 141 °C and other peak is centered at 265 °C. The dose response behaviour has been studied in the range 10 Gy-1000 Gy. However, C ion beam irradiated phosphor also consists similar TL glow curve structure with glow peaks shifted towards high temperature side (approx. 50 °C). The dose response behaviour of C ion beam irradiated phosphor has been examined in the ion fluence range varying from 5 × 109-5 × 1012 ions/cm2. A track interaction model is used to explain the sublinearity at higher fluences of carbon ion beam. Different ion beam parameters have been analyzed using Monte-Carlo simulation-based SRIM code. A comparative TL study of the phosphor irradiated with gamma rays and carbon ion beam suggests that gamma irradiated phosphor has shown better TL properties such as high TL sensitivity, good linear dose response (10 Gy-500 Gy), stable TL glow curve structure and low fading. Various TL trapping parameters i.e. order of kinetics, activation energy and frequency factor have been calculated using Chen's peak shape method to analyze the nature of TL traps responsible for showing different behaviour of the phosphor towards both the radiations. Good TL properties of CaSiO3:Yb phosphor supports its possible use in gamma dosimetry.

Children Left Unattended in Parked Vehicles in India: An Analysis of 40 Fatalities from 2011 to 2020.

BACKGROUND: Fatalities in children left unattended in parked motor vehicles are being reported frequently in the last decade but little research has been done analysing the circumstances leading to such preventable deaths in India. OBJECTIVES: To analyse circumstances leading to fatalities in children left unattended in parked motor vehicles in India. METHODS: This study was a descriptive analysis conducted on the basis of an Internet search of published news in major Indian newspapers/channels using different combination of keywords. We extracted data from the published news using a pre-determined tool. RESULTS: Between 2011 and 2020, there were 23 incidents that resulted in 40 fatalities across India mostly in summer months. Majority of children were 4-6 years of age (26/40). Ninety percent of children gained access to unattended vehicles for playing and getting locked accidentally (36/40) while remaining cases involved being forgotten (3/40) or intentionally left behind (1/40). CONCLUSION: Majority of hyperthermia-related deaths occurred while children gained access to unattended vehicles for playing and getting locked accidentally.

Vertical Transmission of SARS-CoV-2 from an Asymptomatic Pregnant Woman in India.

Severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) is a highly infectious disease with many possible routes of transmission. Vertical transmission of SARS CoV-2 is still controversial. We report a case of vertical transmission of SARS CoV-2 from an asymptomatic pregnant woman to her newborn baby who had completely asymptomatic course in India.

Ion beam modified TiO2 nanotubular bio-interface for electrochemical detection of L-tyrosine towards smart bandage application.

One of the common complications diagnosed in Diabetes Mellitus (DM) patients is Diabetic Foot Ulcers (DFUs). It is a condition wherein the deep tissues located in the lower limb undergo inflammation and infection due to neurological abnormalities (neuropathy) and various degrees of vascular diseases (angiopathy). The concentration of l-tyrosine (Tyr) rises abruptly in DFUs, and therefore may be used as an indicator for early monitoring of the patient's condition during the onset of diabetic foot disease. Herein, we report the electrochemical enzymatic detection of Tyr using low energy ion beam modified titania nanotube (TiNT) thin films with nitrogen (N+) and gold (Au-) ions. Electrochemical Impedance Spectroscopy (EIS) analysis was performed to investigate the levels of Tyr using ion beam modified TiNT thin film electrodes. The modified electrodes exhibited excellent sensor performances with Au-TiNT and N-TiNT within the Tyr concentration range of 100 fM -500 µM with limit of detection (LoD)1.76 nM and 1.25 nM respectively and response time ∼ 1 min. The results indicate that low energy ion beam modified TiNT/enzyme bio-electrodes can potentially be employed as a highly sensitive and portable sensor for real-time detection of l-tyrosine in wound fluids for the development of a smart bandage.

Voltammetric measurements of neurotransmitter-acetylcholine through metallic nanoparticles embedded 2-D material.

The most generally spread neurotransmitter acetylcholine (Ach) is used as a chemical messenger assisting in conveying signals transversely through the nerve synapse. Herein, two enzymes acetylcholinesterase and choline oxidase were covalently immobilized over the gold nanoparticles (AuNPs) embedded graphene oxide (GO; 2D carbon material) nanocomposite modified ITO coated glass plate. The synergetic and unique properties of AuNPs and GO present in nanocomposite are used to detect the ultra-small concentration of analyte, Ach. The prepared nanocomposites were characterized using different techniques i.e. TEM, XRD, SEM, FTIR, UV-Vis and Raman Spectroscopy. All the electrochemical measurements were performed using 3 electrodes integrated electrochemical system by introducing Ach through varying its concentration from 100 pM to 1000 nM. Cyclic voltammetry curves for different concentrations of Ach indicate the facile charge transfer process over the working electrode. Square wave voltammetry curves indicate the good sensing measurements of the modified electrode at the fixed potential. The limit of detection was found to be as low as 100 pM. In addition to these, selectivity of the electrode towards Ach molecule was confirmed by measuring the response towards other interfering agents. Besides this, the present nano interface is capable of detecting Ach in biological fluid such as serum.

Purification/annealing of graphene with 100-MeV Ag ion irradiation.

Studies on interaction of graphene with radiation are important because of nanolithographic processes in graphene-based electronic devices and for space applications. Since the electronic properties of graphene are highly sensitive to the defects and number of layers in graphene sample, it is desirable to develop tools to engineer these two parameters. We report swift heavy ion (SHI) irradiation-induced annealing and purification effects in graphene films, similar to that observed in our studies on fullerenes and carbon nanotubes (CNTs). Raman studies after irradiation with 100-MeV Ag ions (fluences from 3 × 10(10) to 1 × 10(14) ions/cm(2)) show that the disorder parameter α, defined by I D/I G ratio, decreases at lower fluences but increases at higher fluences beyond 1 × 10(12) ions/cm(2). This indicates that SHI induces annealing effects at lower fluences. We also observe that the number of graphene layers is reduced at fluences higher than 1 × 10(13) ions/cm(2). Using inelastic thermal spike model calculations, we estimate a radius of 2.6 nm for ion track core surrounded by a halo extending up to 11.6 nm. The transient temperature above the melting point in the track core results in damage, whereas lower temperature in the track halo is responsible for annealing. The results suggest that SHI irradiation fluence may be used as one of the tools for defect annealing and manipulation of the number of graphene layers. PACS: 60.80.x; 81.05.ue.

Studies on carbon nanotubes and fullerenes under extreme conditions.

Ion beam irradiation of materials can cause defect creation as well as defect annealing depending on the ion beam parameters such as ion fluence and the energy loss of ions in materials. In present review, we report the behaviour of carbon nanotubes under exteme conditions such as laser irradiation and ion irradiation. The reorientation of the crystalline planes in confined single crystal nickel nanorods inside carbon nano tube, induced by heavy ion irradiation, is reported. Axial buckling of nickel nanorods as well as walls of carbon nano tubes in nickel encapsulated carbon nano tubes under swift heavy ion irradiation at high fluence is observed. At high fluence, amorphization of nickel nanorods inside carbon nanotubes is also observed. Axial buckling and amorphization under ion irradiation at high fluence are dependent on the number of walls in carbon nanotubes. High resolution transmission electron microscopy was used to investigate the reorientations, buckling and amorphization of metal filled nanotubes. Synthesis of carbon nanowires by ion irradiation of fullerene and their field emission properties with comparison to that of unirradiated and irradiated carbon nanotubes are reported. An international scenario with future prospects of ion beam studies in carbon nanotube is briefed.