Passive Gas-Liquid Separation Using Hydrophobic Porous Polymer Membranes: A Study on the Effect of Operating Pressure on Membrane Area Requirement

The use of hydrophobic porous polymer membranes to vent unwanted gas bubbles from liquid streams is becoming increasingly more common in portable applications such as direct methanol fuel cells (DMFCs) and micro-fluidic cooling of electronic circuits. In order for these portable systems to keep up with the ever increasing demand of the mobile user, it is essential that auxiliary components, like gas-liquid separators (GLS), continue to decrease in weight and size. While there has been significant progress made in the field of membrane-based gas-liquid separation, the ability to miniaturize such devices has not been thoroughly addressed in the available literature. Thus, it was the purpose of this work to shed light on the scope of GLS miniaturization by examining how the amount porous membrane required to completely separate gas bubbles from a liquid stream varies with operating pressure. Two membrane characterization experiments were also employed to determine the permeability, k, and liquid entry pressure (LEP) of the membrane, which provided satisfying results. These parameters were then implemented into a mathematical model for predicting the theoretical membrane area required for a specified two-phase flow, and the results were compared to experimental values. It was shown that the drastically different surface properties of the wetted materials within the GLS device, namely polytetrafluoroethylene (PTFE) and acrylic, caused the actual membrane area requirement to be higher than the theoretical predictions by a constant amount. By analyzing the individual effects of gas and liquid flow, it was also shown that the membrane area requirement increased significantly when the liquid velocity exceeded an amount necessary to cause the flow regime to transition from wedging/slug flow to wavy/semi-annular flow

Theodor Billroth and his musical life.

Although most widely recognized for the two types of gastric reconstructions that bear his name, Christian Albert Theodor Billroth was one of the most innovative surgeons of his time. His contributions included developing techniques for procedures on the larynx, breast, and esophagus. He pioneered sterility and antisepsis in operating rooms. He also improved surgical education by advocating for longer apprenticeships, which helped create a framework for today’s residency programs. However, what often goes unnoticed was Dr. Billroth’s love for music, a passion that fueled him throughout his life

Leveraging Contact Network Information in Clustered Randomized Studies of Contagion Processes

In a randomized study, leveraging covariates related to the outcome (e.g. disease status) may produce less variable estimates of the effect of exposure. For contagion processes operating on a contact network, transmission can only occur through ties that connect affected and unaffected individuals; the outcome of such a process is known to depend intimately on the structure of the network. In this paper, we investigate the use of contact network features as efficiency covariates in exposure effect estimation. Using augmented generalized estimating equations (GEE), we estimate how gains in efficiency depend on the network structure and spread of the contagious agent or behavior. We apply this approach to simulated randomized trials using a stochastic compartmental contagion model on a collection of model-based contact networks and compare the bias, power, and variance of the estimated exposure effects using an assortment of network covariate adjustment strategies. We also demonstrate the use of network-augmented GEEs on a clustered randomized trial evaluating the effects of wastewater monitoring on COVID-19 cases in residential buildings at the the University of California San Diego.Comment: Substantial revisio

Munhu: Unlocking the Roots, Indigenous Knowledge for Development

This paper is based on both written academic literature and Shona oral traditions. The paper looks at the conceptual framework, practice, and understanding of the muntu / munhu philosophy. The lateral translation of muntu / munhu is person. Conceptually the word goes deeper than this individualistic western worldview. Munhu is complex, multifaceted and generally understood at two levels; the lower and higher level. At lower level munhu means the physical body of a human being. At higher level munhu becomes the physical body and a lot of other extras. This paper argues that the concept of munhu (humanity) is the foundation of life and the only key to stability and progress / development among Africans. Destroying the human body or even showing disrespect to that body is a punishable offence. Thus whether munhu is understood at lower (physical) or higher (spiritual plus) level, munhu is sacred and has to be treated with respect for progress, wellbeing and development of the humankind. If respected, munhu will contribute towards both personal and communal development. In fact, in Africa the personal is communal

Investigating Heat Loss through Vestibule Doors for a Non-Residential Building

The aim of this study was to investigate the effects of air flow movement through high use front entrance doors of a college building with large flows of people. The objectives were to visualize and quantify the resultant energy losses through the entrance doors, coupled with investigating any potential improvements that can be obtained through improved design. The findings of the study suggest that the heat loss from the front entrance design can contribute to up to 2.8% of the buildings’ energy loads. It was also seen that a vestibule creates a tunnel effect for cold ambient air to enter the building without hot air escaping from the vestibule. Rather hot stale air exits through openings at the ceiling height. Potential solutions with entrance design are investigated and their results compared to the outcomes of a similar model designed using Computational Fluid Dynamics (CFD)

A Middle Jurassic (Bajocian) ophthalmosaurid (Reptilia, Ichthyosauria) from the Tuxedni Formation, Alaska and the early diversification of the clade

Ophthalmosauridae is a clade of derived thunniform ichthyosaurs that are best known from Callovian (late Middle Jurassic) to Cenomanian-aged (Late Cretaceous) deposits in both the Northern and Southern Hemispheres. Ophthalmosaurids arose prior to the Early-Middle Jurassic boundary, however, very little is known about their diversity and distribution in the earliest phase of their evolutionary history during the Aalenian-Bathonian (Middle Jurassic) interval. Here we describe new diagnostic ophthalmosaurid material from the Early Bajocian (Middle Jurassic) of Alaska. The specimen, UAMES 3411, is a partial disarticulated skull that was discovered in the Middle Jurassic Tuxedni Formation, which was deposited in shallow marine settings outboard of the then-accreting Wrangellia composite terrane. The new material is significant in that it is the first Jurassic ichthyosaur described from Alaska, one of the oldest ophthalmosaurids known and the only Middle Jurassic ophthalmosaurid described from the Northern Hemisphere. The new material adds to a rapidly growing data set on ophthalmosaurid diversity and suggests that the clade was geographically widespread by the Early Bajocian, very early in its evolutionary histor

Improving Performance in the African Civil Service: Empirical Evidence from Zimbabwe.

Most African governments have attempted improving performance of their civil service through reforms. All ended up failing meeting the desired results because of a combination of internal and external factors. The Zimbabwean experience is a typical African reforms effort that failed because of both internal weaknesses and external pressures. This paper looks at the theoretical frameworks and the implementation of reform programmes in the Zimbabwean civil service. Key words: Improving performance, performance management, corruption, change

Gender Dynamics and Women In Conflict Situations And Post Conflict Recovery: Experiences From Africa.

The purpose of this paper is to construct a framework for understanding the gender dimensions of post-conflict reconstruction in order to strengthen assessments, project design, and policy-formulation; all with the aim of achieving the overarching goals of sustainable peace, participation and prosperity. The paper advocates for gender sensitive policies, activities and programmes that may promote gender equality, and enhance returns on post conflict recovery and reconstruction investments. It is predicated on the conviction that building and maintaining peace and prosperity requires attention to gender roles and relations in the post-conflict arena. We propose ways to undertake social, economic and political development within a particularised context (that is post-conflict): recognising gender-related challenges, suggesting ways that a ‘gender lense’ may sharpen understanding, and capitalising on opportunities presented by new rules, institutions and resources. Key words: Conflict, recovery, reconstruction, women, gender, sexual violence

Ranks, Subdegrees and Suborbital graphs of the product action of Affine Groups

The action of affine groups on Galois field has been studied.  For instance,  studied the action of on Galois field for  a power of prime.  In this paper, the rank and subdegree of the direct product of affine groups over Galois field acting on the cartesian product of Galois field is determined. The application of the definition of the product action is used to achieve this. The ranks and subdegrees are used in determination of suborbital graph, the non-trivial suborbital graphs that correspond to this action have been constructed using Sims procedure and were found to have a girth of 0, 3, 4 and 6