Browsing by Author "Tuovinen, Henri"

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    Evaluation of the effects of nanoprecipitation process parameters on the size and morphology of poly(ethylene oxide)-block-polycaprolactone nanostructures
    (Elsevier, 2020-11-30) Känkänen, Voitto; Seitsonen, Jani; Tuovinen, Henri; Ruokolainen, Janne; Hirvonen, Jouni; Balasubramanian, Vimalkumar; Santos, Hélder A.; Department of Applied Physics; Molecular Materials; University of Helsinki; Bayer AG
    Nanoprecipitation is a straightforward method for the production of block copolymer nanoparticles for drug delivery applications. However, the effects of process parameters need to be understood to optimize and control the particle size distribution (PSD). To this end, we investigated the effects of material and process factors on PSD and morphology of nanoparticles prepared from an amphiphilic diblock copolymer, poly(ethylene oxide)-block-polycaprolactone. Using a Design of Experiments approach, we explored the joint effects of molecular weight, block length ratios, water volume fraction, stirring rate, polymer concentration and organic phase addition rate on hydrodynamic size and polydispersity index of the nanostructures and created statistical models explaining up to 94% of the variance in hydrodynamic diameter. In addition, we performed morphological characterization by cryogenic transmission electron microscopy and showed that increasing the process temperature may favor the formation of vesicles from these polymers. We showed that the effects of process parameters are dependent on the polymer configuration and we found that the most useful parameters to fine-tune the PSD are the initial polymer concentration and the stirring rate. Overall, this study provides evidence on the joint effects of material and process parameters on PSD and morphology, which will be useful for rational design of formulation-specific optimization studies, scale-up and process controls.
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    FPGA implementation of confidential computing enclave
    (2024-03-11) Tuovinen, Henri; Järvinen, Kimmo; Jehkonen, Petri; Sähkötekniikan korkeakoulu; Ryynänen, Jussi
    The use of cloud computing resources has continued to rise over the last decade. Cloud computing enables the use of efficient distributed services. However, data confidentiality cannot be guaranteed in currently used cloud systems shared between different parties. Data confidentiality cannot be guaranteed since the cloud systems use Central Processing Units (CPU) and program code that have well known vulnerabilities. This thesis studies a confidential computing enclave implementation on a Field-Programmable Gate Array (FPGA) that may be a cloud resource. This solution enables performing remote computation securely in an isolated enclave. The studied solution enables a client to upload its data and program code to an enclave securely over the internet. The data is then processed in the secure enclave and the result can only be read by the client. The aim of this thesis is designing and implementing a Proof Of Concept (POC) FPGA confidential computing enclave. The POC is designed utilizing two pre-existing company intellectual property solutions a Transmission Control Protocol / Internet Protocol (TCP/IP) software stack to establish internet connectivity and a Transport Layer Security (TLS) module to establish secure communication. In this thesis an enclave module and a connection controller module are designed and implemented using SystemVerilog Hardware Description Language (HDL). The expected behavior of the designed modules is verified with simulation. Furthermore, the enclave functionality is verified and demonstrated by programming it on an FPGA and communicating with the enclave over a Local Area Network (LAN) using a computer. The POC implementation is deemed successful and feasible to implement in a technical sense. The POC architecture is estimated to be similar to the state-of-the-art and in comparison implements the TLS 1.3 protocol.
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    Laskuripohjaiset taajuusjakajapiirit
    (2020-05-25) Tuovinen, Henri; Cheung, Tze Hin; Sähkötekniikan korkeakoulu; Turunen, Markus