Bubble oscillations at low frequency ultrasound for biological applications.

Bubbles oscillating in the presence of ultrasound is commonly employed in biomedical applications for drug delivery, ultrasound enhanced thrombolysis, and the transport and manipulation of cells. This is possible because bubbles tend to interact with the ultrasound to undergo periodic shape changes known as shape-mode oscillation, concomitant with the generation of liquid agitation or streaming. This phenomenon is examined both experimentally and theoretically on a single bubble at a frequency of (45 ± 1) kHz. Effects of ultrasonic frequency and power on the flowfield were explored. Experiments revealed different trends in the development of liquid streaming velocities at different acoustic forcing conditions (5.53, 6.80 and 7.02 Vpp), with lowest (0.5 mm/s) and highest (1.1 mm/s) values of time-averaged mean streaming velocity occurring at 6.80 Vpp and 7.02 Vpp, respectively. Simulations captured the simultaneous evolution of bubble-shapes that helped create flow vortices in the liquid surrounding the bubble. These vortices collectively responsible in generating signature patterns in the liquid for a dominant shape-mode of the bubble, and could also generate localised shear stresses for practical application. The velocity and pressure profiles in the liquid around the bubble confirmed the connection of the applied and reflected soundwaves in driving this phenomenon.

Technical, economic and environmental feasibility of resource recovery technologies from wastewater.

An enormous amount of wastewater is generated across the world from different industrial or municipal sectors. Traditional wastewater treatment plants (WWTP) have primarily focused on the treatment of wastewater rather than the recovery of valuable resources. A shift from a linear to a circular economy may offer a unique platform for recovering valuable resources including energy, nutrients, and high-value goods from wastewater. However, transitioning from conventional frameworks to sustainable WWT systems remains a significant challenge. Thus, this review paper focuses on the avenues of resource recovery from WWTPs, by evaluating the potential for nutrients, water, and energy recovery from different types of wastewaters and sewage sludge. It discusses in detail a variety of available and advanced technologies for resource recovery. Further, the feasibility of these technologies from a sustainable standpoint is discussed, covering the technical, economic, and environmental facets.

Acoustic cavitation at low gas pressures in PZT-based ultrasonic systems.

The generation of cavitation-free radicals through evanescent electric field and bulk-streaming was reported when micro-volumes of a liquid were subjected to 10 MHz surface acoustic waves (SAW) on a piezoelectric substrate [Rezk et al., J. Phys. Chem. Lett. 2020, 11, 4655-4661; Rezk et al., Adv. Sci. 2021, 8, 2001983]. In the current study, we have tested a similar hypothesis with PZT-based ultrasonic units (760 kHz and 2 MHz) with varying dissolved gas concentrations, by sonochemiluminescence measurement and iodide dosimetry, to correlate radical generation with dissolved gas concentrations. The dissolved gas concentration was adjusted by controlling the over-head gas pressure. Our study reveals that there is a strong correlation between sonochemical activity and dissolved gas concentration, with negligible sonochemical activity at near-vacuum conditions. We therefore conclude that radical generation is dominated by acoustic cavitation in conventional PZT-based ultrasonic reactors, regardless of the excitation frequency.

Acoustic cavitation-induced shear: a mini-review.

Acoustic cavitation (or the formation of bubbles using acoustic or ultrasound-based devices) has been extensively exploited for biological applications in the form of bioprocessing and drug delivery/uptake. However, the governing parameters behind the several physical effects induced by cavitation are generally lacking in quantity in terms of suitable operating parameters of ultrasonic units. This review elaborates the current gaps in this realm and summarizes suitable investigative tools to explore the shear generated during cavitation. The underlying physics behind these events are also discussed. Furthermore, current advances of acoustic shear on biological specimens as well as future prospects of this cavitation-induced shear are also described.

Tracking the migration of the Indian continent using the carbonate clumped isotope technique on Phanerozoic soil carbonates.

Approximately 140 million years ago, the Indian plate separated from Gondwana and migrated by almost 90° latitude to its current location, forming the Himalayan-Tibetan system. Large discrepancies exist in the rate of migration of Indian plate during Phanerozoic. Here we describe a new approach to paleo-latitudinal reconstruction based on simultaneous determination of carbonate formation temperature and δ(18)O of soil carbonates, constrained by the abundances of (13)C-(18)O bonds in palaeosol carbonates. Assuming that the palaeosol carbonates have a strong relationship with the composition of the meteoric water, δ(18)O carbonate of palaeosol can constrain paleo-latitudinal position. Weighted mean annual rainfall δ(18)O water values measured at several stations across the southern latitudes are used to derive a polynomial equation: δ(18)Ow = -0.006 × (LAT)(2) - 0.294 × (LAT) - 5.29 which is used for latitudinal reconstruction. We use this approach to show the northward migration of the Indian plate from 46.8 ± 5.8°S during the Permian (269 M.y.) to 30 ± 11°S during the Triassic (248 M.y.), 14.7 ± 8.7°S during the early Cretaceous (135 M.y.), and 28 ± 8.8°S during the late Cretaceous (68 M.y.). Soil carbonate δ(18)O provides an alternative method for tracing the latitudinal position of Indian plate in the past and the estimates are consistent with the paleo-magnetic records which document the position of Indian plate prior to 135 ± 3 M.y.

Strangulated double omental hernia presenting as an epigastric lump.

Internal herniations constitute one of the relatively uncommon surgical emergencies. Among them double omental hernia with bowel strangulation is very rare and is a major diagnostic challenge. A case of a strangulated double omental hernia in a 42-year-old female patient is reported. The patient presented with a painful tender epigastric lump.There was a diagnostic dilemma. CT scan was followed by laparotomy which revealed a strangulated double omental hernia.

An epidemiological analysis of patients with abdominal trauma in an eastern Indian metropolitan city.

The profile and pattern of abdominal trauma is changing with progressing civilisation. We are lacking epidemiological data from most parts of the world. This study was conducted to prepare a database in our set up and look into the pattern of abdominal trauma, make an aetiological correlation of abdominal trauma with the types of injuries, identify the preventable factors causing delay in intervention and, compare the data with the other available national and international data. This prospective, observational study was done in a teaching hospital in a metropolitan city of eastern India. Records of patients with abdominal trauma were collected in predesigned forms, from admission to discharge. Data were analysed applying standard statistical techniques. Males (87.3%) predominated with the age range between 21 and 30 years, and the majority (73.5%) had blunt abdominal trauma. Compression injury (57.3%) commonly caused blunt trauma and stab injuries caused majority of penetrating trauma. The commonest organ injured both in blunt and penetrating trauma was small bowel (30.7% and 33.3% respectively). It was found that prehospital trauma care is virtually non-existent in this region. We are lacking a uniform protocol for the management of abdominal trauma across the hospitals. With the availability of better investigational modalities we are moving more towards a conservative approach to the abdominal trauma patients, especially the blunt abdominal trauma patients with solid organ injuries.

Bilaterally symmetric Fourier approximations of the skull outlines of temnospondyl amphibians and their bearing on shape comparison.

Present work illustrates a scheme of quantitative description of the shape of the skull outlines of temnospondyl amphibians using bilaterally symmetric closed Fourier curves. Some special points have been identified on the Fourier fits of the skull outlines, which are the local maxima, or minima of the distances from the centroid of the points at the skull outline. These points denotes break in curvature of the outline and their positions can be compared to differentiate the skull shapes. The ratios of arc-lengths of the posterior and lateral outline of 58 temnospondyl skulls have been plotted to generate a triaguarity series of the skulls. This series grades different families, some of their genera and species as well as some individuals according to their posterior and lateral skull length ratios. This model while comparing different taxa, takes into account the entire arc-length of the outline of the temnospondyl skulls, and does not depend on few geometric or biological points used by earlier workers for comparing skull shapes.